Science.gov

Sample records for corrugated plastic

  1. Singing Corrugated Pipes

    ERIC Educational Resources Information Center

    Crawford, Frank S.

    1974-01-01

    Presents theoretical and experimental observations made with a musical toy called Hummer consisting of a corrugated flexible plastic tube about three-feet long and one-inch diam open at both ends. Included are descriptions of three new instruments: the Water Pipe, the Gas-Pipe Corrugahorn Bugle, and the Gas-Pipe Blues Corrugahorn. (CC)

  2. Birefringent corrugated waveguide

    DOEpatents

    Moeller, Charles P.

    1990-01-01

    A corrugated waveguide having a circular bore and noncircularly symmetric corrugations, and preferably elliptical corrugations, provides birefringence for rotation of polarization in the HE.sub.11 mode. The corrugated waveguide may be fabricated by cutting circular grooves on a lathe in a cylindrical tube or rod of aluminum of a diameter suitable for the bore of the waveguide, and then cutting an approximation to ellipses for the corrugations using a cutting radius R.sub.0 from the bore axis that is greater than the bore radius, and then making two circular cuts using a radius R.sub.1 less than R.sub.0 at centers +b and -b from the axis of the waveguide bore. Alternatively, stock for the mandrel may be formed with an elliptical transverse cross section, and then only the circular grooves need be cut on a lathe, leaving elliptical corrugations between the grooves. In either case, the mandrel is first electroplated and then dissolved leaving a corrugated waveguide with noncircularly symmetric corrugations. A transition waveguide is used that gradually varies from circular to elliptical corrugations to couple a circularly corrugated waveguide to an elliptically corrugated waveguide.

  3. Birefringent corrugated waveguide

    SciTech Connect

    Moeller, C.P.

    1990-03-06

    This patent describes a corrugated waveguide having a circular bore and noncircularly symmetric corrugations, and preferably elliptical corrugations which provides birefringence for rotation of polarization in the HE{sub 11} mode. The corrugated waveguide may be fabricated by cutting circular grooves on a lathe in a cylindrical tube or rod of aluminum of a diameter suitable for the bore of the waveguide, and then cutting an approximation to ellipses for the corrugations using a cutting radius R{sub 0} from the bore axis that is greater than the bore radius, and then making two circular cuts using a radius R{sub 1} less than R{sub 0} at centers + b and {minus} B from the axis of the waveguide bore. Alternatively, stock for the mandrel may be formed with an elliptical transverse cross section, and then only the circular grooves need be cut on a lathe, leaving elliptical corrugations between the grooves. In either case, the mandrel is first electroplated and then dissolved leaving a corrugated waveguide with noncircularly symmetric corrugations. A transition waveguide is used that gradually varies from circular to elliptical corrugations to couple a circularly corrugated waveguide to an elliptically corrugated waveguide.

  4. Birefringent corrugated waveguide

    SciTech Connect

    Moeller, C.P.

    1989-02-15

    A corrugated waveguide having a circular bore and noncircularly symmetric corrugations, and preferably elliptical corrugations, provides birefringence for rotation of polarization in the HE{sub 11} mode. The corrugated waveguide may be fabricated by cutting circular grooves on a lathe in a cylindrical tube or rod of aluminium of a diameter suitable for the bore of the waveguide, and then cutting an approximation to ellipses for the corrugations using a cutting radius R{sub 0} from the bore axis that is greater than the bore radius, and then making two circular cuts using a radius R{sub 1} less than R{sub 0} at centers +b and {minus}b from the axis of the waveguide bore. Alternatively, stock for the mandrel may be formed with an elliptical transverse cross section, and then only the circular grooves need be cut on a lathe, leaving elliptical corrugations between the grooves. In either case, the mandrel is first electroplated and then dissolved leaving a corrugated waveguide with noncircularly symmetric waveguides. A transition waveguide is used that gradually varies from circular to elliptical corrugations to couple a circularly corrugated waveguide to an elliptically corrugated waveguide.

  5. Corrugated Cardboard Scenery Construction.

    ERIC Educational Resources Information Center

    Wedwick, Daryl M.

    The use of corrugated cardboard in constructing stage scenery is discussed in this paper. In the first section, both the advantages and the problems associated with using the material are discussed, as are ways to avoid problems. The second section of the paper discusses general methods for preparing corrugated materials for set and prop…

  6. Industrial fabrication of an optical security device for document protection using plasmon resonant transmission through a thin corrugated metallic film embedded on a plastic foil

    NASA Astrophysics Data System (ADS)

    Sauvage-Vincent, Jean; Jourlin, Yves; Tonchev, Svetlen; Veillas, Colette; Claude, Pedri; Parriaux, Olivier

    2012-06-01

    Known since a long time in polymer banknotes and presented in the few years in paper banknotes, the principle of windowed documents has been currently extended to ID documents. We present an innovative solution which combines resonant transmission and Zero Order Device technologies and which is dedicated to improve windows in terms of the overt security level. With this R&D program, Hologram Industries targeted to obtain an overt visual security device that should be readily checked in transmission in the same manner as the established paper watermark. The proposed solution is based on the propagation of resonant modes in a thin continuous corrugated metallic layer embedded (encapsulated) between two dielectric layers of near equal refractive index. The mode of most interest is the Long Range Plasmon Mode. The coupling condition to the Long Range Mode is principally related to the corrugation, the metal layer thickness and the index of the two dielectric layers. If the condition of the mode excitation through the grating is fulfilled, a predetermined wavelength will be coupled to the Long Range Plasmon Mode. This mode will propagate at each metal/dielectric interface with a low loss and will concentrate the electric field inside the metal layer. This effect of coupling enables the transmission of a peak at this wavelength through the metallic layer. It defines the so called "extraordinary resonant transmission".

  7. Properties of cutoff corrugated surfaces for corrugated horn design. [corrugation shape and density effects on scattering

    NASA Technical Reports Server (NTRS)

    Mentzer, C. A.; Peters, L., Jr.

    1974-01-01

    Corrugated horns involve a junction between the corrugated surface and a conducting ground plane. Proper horn design requires an understanding of the electromagnetic properties of the corrugated surface and this junction. An integral equation solution has been used to study the influence of corrugation density and tooth thickness on the power loss, surface current, and the scattering from a ground plane/corrugated surface junction.

  8. An Improved Method of Manufacturing Corrugated Boxes: Lateral Corrugator

    SciTech Connect

    Frank C. Murray Ph.D.; , Roman Popil Ph.D.; Michael Shaepe

    2008-12-18

    Paper physicists have known that a corrugated box constructed from outer liner sheets having a predominant fiber orientation aligned with the corrugating flute direction would have higher stiffness and crush resistance (per unit of fiber weight) than the conventional box construction. Such increased performance per unit of fiber weight could result in fiber reduction and energy savings for boxes having equivalent performance specifications. The goal of this project was to develop and demonstrate a commercially viable lateral corrugating process. This included designing and building a pilot lateral corrugator, testing and evaluating pilot machine made boxes, and developing a strategy for commercialization.

  9. Linear Corrugating - Final Technical Report

    SciTech Connect

    Lloyd Chapman

    2000-05-23

    Linear Corrugating is a process for the manufacture of corrugated containers in which the flutes of the corrugated medium are oriented in the Machine Direction (MD) of the several layers of paper used. Conversely, in the conventional corrugating process the flutes are oriented at right angles to the MD in the Cross Machine Direction (CD). Paper is stronger in MD than in CD. Therefore, boxes made using the Linear Corrugating process are significantly stronger-in the prime strength criteria, Box Compression Test (BCT) than boxes made conventionally. This means that using Linear Corrugating boxes can be manufactured to BCT equaling conventional boxes but containing 30% less fiber. The corrugated container industry is a large part of the U.S. economy, producing over 40 million tons annually. For such a large industry, the potential savings of Linear Corrugating are enormous. The grant for this project covered three phases in the development of the Linear Corrugating process: (1) Production and evaluation of corrugated boxes on commercial equipment to verify that boxes so manufactured would have enhanced BCT as proposed in the application; (2) Production and evaluation of corrugated boxes made on laboratory equipment using combined board from (1) above but having dual manufactures joints (glue joints). This box manufacturing method (Dual Joint) is proposed to overcome box perimeter limitations of the Linear Corrugating process; (3) Design, Construction, Operation and Evaluation of an engineering prototype machine to form flutes in corrugating medium in the MD of the paper. This operation is the central requirement of the Linear Corrugating process. Items I and II were successfully completed, showing predicted BCT increases from the Linear Corrugated boxes and significant strength improvement in the Dual Joint boxes. The Former was constructed and operated successfully using kraft linerboard as the forming medium. It was found that tensile strength and stretch

  10. Stacked Corrugated Horn Rings

    NASA Technical Reports Server (NTRS)

    Sosnowski, John B.

    2010-01-01

    This Brief describes a method of machining and assembly when the depth of corrugations far exceeds the width and conventional machining is not practical. The horn is divided into easily machined, individual rings with shoulders to control the depth. In this specific instance, each of the corrugations is identical in profile, and only differs in diameter and outer profile. The horn is segmented into rings that are cut with an interference fit (zero clearance with all machining errors biased toward contact). The interference faces can be cut with a reverse taper to increase the holding strength of the joint. The taper is a compromise between the interference fit and the clearance of the two faces during assembly. Each internal ring is dipped in liquid nitrogen, then nested in the previous, larger ring. The ring is rotated in the nest until the temperature of the two parts equalizes and the pieces lock together. The resulting assay is stable, strong, and has an internal finish that cannot be achieved through other methods.

  11. Acoustical studies on corrugated tubes

    NASA Astrophysics Data System (ADS)

    Balaguru, Rajavel

    Corrugated tubes and pipes offer greater global flexibility combined with local rigidity. They are used in numerous engineering applications such as vacuum cleaner hosing, air conditioning systems of aircraft and automobiles, HVAC control systems of heating ducts in buildings, compact heat exchangers, medical equipment and offshore gas and oil transportation flexible riser pipelines. Recently there has been a renewed research interest in analyzing the flow through a corrugated tube to understand the underlying mechanism of so called whistling, although the whistling in such a tube was identified in early twentieth century. The phenomenon of whistling in a corrugated tube is interesting because an airflow through a smooth walled tube of similar dimensions will not generate any whistling tones. Study of whistling in corrugated tubes is important because, it not only causes an undesirable noise problem but also results in flow-acoustic coupling. Such a coupling can cause significant structural vibrations due to flow-acoustic-structure interaction. This interaction would cause flow-induced vibrations that could result in severe damage to mechanical systems having corrugated tubes. In this research work, sound generation (whistling) in corrugated tubes due to airflow is analyzed using experimental as well as Computational Fluid Dynamics-Large Eddy Simulation (CFD-LES) techniques. Sound generation mechanisms resulting in whistling have been investigated. The whistling in terms of frequencies and sound pressure levels for different flow velocities are studied. The analytical and experimental studies are carried out to understand the influence of various parameters of corrugated tubes such as cavity length, cavity width, cavity depth, pitch, Reynolds numbers and number of corrugations. The results indicate that there is a good agreement between theoretically calculated, computationally predicted and experimentally measured whistling frequencies and sound pressure levels

  12. Mass transfer in corrugated membranes

    NASA Astrophysics Data System (ADS)

    Gronda, Ann Mclaughry

    Research on the chemical and physical structure of membranes has failed to overcome the inverse relationship between selectivity and permeability. While this permeability is partially responsible for the rate of separation, the geometry of the membrane contributes significantly to this rate. In this work, we focused on the system geometry by examining the effect of corrugations on the rate of membrane separations. We developed a theory to describe mass transport in corrugations and to predict the effectiveness of corrugated membranes. To verify this theory, membranes with millimeter-sized corrugations were made. Pervaporation experiments with highly permeable and less permeable solutes showed excellent agreement with the theory. Based on the membrane geometry and permeability, the effectiveness factor and the flux enhancement can be quantified by a modified Thiele analysis. We used this theory to examine the effect of small corrugations on the mass transfer of both liquids and gases across membranes, including the effects of free convection, membrane supports, and Knudsen diffusion. In systems with a liquid feed, corrugations are promising only for very impermeable solutes. In gases, corrugations are more effective, especially when supported by a porous structure. We attempted to make smaller corrugations in two ways. The more promising method is phase-inversion of diblock copolymers. These diblocks were dissolved in a solvent, made into a thin film, and immersed in a liquid that was a nonsolvent for the majority block and a solvent for the minority block. In this way, we attempted to draw the minority block to the surface of an undulating structure created by the phase inversion. Ideally, the minority block would be selective and the majority block would be highly permeable or porous. Scanning electron microscopy showed promising structures made from polystyrene-polyisoprene and polyacrylonitrile-polyethylene oxide. The other, less promising, attempt at making

  13. Modeling of a corrugated dielectric elastomer actuator for artificial muscle applications

    NASA Astrophysics Data System (ADS)

    Kadooka, Kevin; Taya, Minoru; Naito, Keishi; Saito, Makoto

    2015-04-01

    Dielectric elastomer actuators have many advantages, including light weight, simplicity, high energy density, and silent operation. These features make them suitable to replace conventional actuators and transducers, especially in artificial muscle applications where large contractile strains are necessary for lifelike motions. This paper will introduce the concept of a corrugated dielectric elastomer actuator (DEA), which consists of dielectric elastomer (DE) laminated to a thin elastic layer to induce bending motion at each of the corrugations, resulting in large axial deformation. The location of the DE and elastic layers can be configured to provide tensile or compressive axial strain. Such corrugated DE actuators are also highly scalable: linking multiple actuators in series results in greater deformation, whereas multiple actuators in parallel results in larger force output. Analytical closed-form solutions based on linear elasticity were derived for the displacement and force output of curved unimorph and corrugated DEA, both consisting of an arbitrary number of lamina. A total strain energy analysis and Castigiliano's theorem were used to predict the nonlinear force-displacement behavior of the corrugated actuator. Curved unimorph and corrugated DEA were fabricated using VHB F9469PC as the DE material. Displacement of the actuators observed during testing agreed well with the modeling results. Large contractile strain (25.5%) was achieved by the corrugated DEA. Future work includes investigating higher performance DE materials such as plasticized PVDF terpolymers, processed by thin film deposition methods.

  14. Transient disturbance growth in a corrugated channel

    NASA Astrophysics Data System (ADS)

    Szumbarski, J.; Floryan, J. M.

    2006-12-01

    Transient growth of small disturbances may lead to the initiation of the laminar turbulent transition process. Such growth in a two-dimensional laminar flow in a channel with a corrugated wall is analysed. The corrugation has a wavy form that is completely characterized by its wavenumber and amplitude. The maximum possible growth and the form of the initial disturbance that leads to such growth have been identified for each form of the corrugation. The form that leads to the largest growth for a given corrugation amplitude, i.e. the optimal corrugation, has been found. It is shown that the corrugation acts as an amplifier for disturbances that are approximately optimal in the smooth channel case but has little effect in the other cases. The interplay between the modal (asymptotic) instability and the transient growth, and the use of the variable corrugation for modulation of the growth are discussed.

  15. Corrugated Membrane Fuel Cell Structures

    SciTech Connect

    Grot, Stephen

    2013-09-30

    One of the most challenging aspects of traditional PEM fuel cell stacks is the difficulty achieving the platinum catalyst utilization target of 0.2 gPt/kWe set forth by the DOE. Good catalyst utilization can be achieved with state-of-the-art catalyst coated membranes (CCM) when low catalyst loadings (<0.3 mg/cm2) are used at a low current. However, when low platinum loadings are used, the peak power density is lower than conventional loadings, requiring a larger total active area and a larger bipolar plate. This results in a lower overall stack power density not meeting the DOE target. By corrugating the fuel cell membrane electrode structure, Ion Power?s goal is to realize both the Pt utilization targets as well as the power density targets of the DOE. This will be achieved by demonstrating a fuel cell single cell (50 cm2) with a twofold increase in the membrane active area over the geometric area of the cell by corrugating the MEA structure. The corrugating structure must be able to demonstrate the target properties of < 10 mOhm-cm2 electrical resistance at > 20 psi compressive strength over the active area, in combination with offering at least 80% of power density that can be achieved by using the same MEA in a flat plate structure. Corrugated membrane fuel cell structures also have the potential to meet DOE power density targets by essentially packaging more membrane area into the same fuel cell volume as compared to conventional stack constructions.

  16. Wakefield potentials of corrugated structures

    DOE PAGES

    Novokhatski, A.

    2015-10-22

    A corrugated structure, which is used in “dechirper” devices, is usually a pipe or two plates with small corrugations (bumps) on the walls. There is a good single-mode description of the wake potentials excited by a relativistic bunch if the wave length of the mode is much longer than the distance between the bumps in the pipe. However, ultrashort bunches, which are now used in free electron lasers, excite much higher frequency fields and the corresponding wake potentials will be very different from the single-mode description. We have made analyses of these wake potentials based on a numerical solution ofmore » Maxwell’s equations. It was confirmed that the behavior of the wakefields of ultrashort bunches in corrugated structures is not much different from the fields excited usually in accelerating structures where the wake potentials are described by the exponential function. For a practical application we present results for the SLAC “dechirper.” We also carried out calculations for a similar device, that was installed and measured at the Pohang Accelerator Laboratory, Korea. As a result, we find very good agreement with the experimental results.« less

  17. Numerical and Experimental Investigations on Mechanical Behavior of Composite Corrugated Core

    NASA Astrophysics Data System (ADS)

    Dayyani, Iman; Ziaei-Rad, Saeed; Salehi, Hamid

    2012-06-01

    Tensile and flexural characteristics of corrugated laminate panels were studied using numerical and analytical methods and compared with experimental data. Prepreg laminates of glass fiber plain woven cloth were hand-laid by use of a heat gun to ease the creation of the panel. The corrugated panels were then manufactured by using a trapezoidal machined aluminium mould. First, a series of simple tension tests were performed on standard samples to evaluate the material characteristics. Next, the corrugated panels were subjected to tensile and three-point bending tests. The force-displacement graphs were recorded. Numerical and analytical solutions were proposed to simulate the mechanical behavior of the panels. In order to model the energy dissipation due to delamination phenomenon observed in tensile tests in all members of corrugated core, plastic behavior was assigned to the whole geometry, not only to the corner regions. Contrary to the literature, it is shown that the three-stage mechanical behavior of composite corrugated core is not confined to aramid reinforced corrugated laminates and can be observed in other types such as fiber glass. The results reveal that the mechanical behavior of the core in tension is sensitive to the variation of core height. In addition, for the first time, the behavior of composite corrugated core was studied and verified in bending. Finally, the analytical and numerical results were validated by comparing them with experimental data. A good degree of correlation was observed which showed the suitability of the finite element model for predicting the mechanical behavior of corrugated laminate panels.

  18. A rail joint: The possible initiator of corrugation?

    NASA Astrophysics Data System (ADS)

    Hoelzl, G.

    The corrugation found at a rail joint which seems to be the initiator of the formation of corrugation is investigated. The possibility that the development of corrugations depends on the magnitude of the traffic is discussed. Several corrugation profiles and roughness spectra were measured. The results indicate that the corrugation can be caused by the start of the locomotives motion at the rail road crossing. Such corrugations were also found in stations at places where locomotives usually start to move.

  19. Biaxially corrugated flexible sheet material

    DOEpatents

    Schmertz, John C.

    1991-04-16

    A flexible biaxially corrugated sheet material is formed from a plurality of identical trapezium segments which are arranged in a plurality of long strips a single segment wide. Adjacent strips are mirror images of each other and connected along adjoining sides with the angles of the four corners of adjacent segments being alternately less than 360.degree. and greater than 360.degree. along the length of a strip such that the sheet material has an undulating configuration, and is inherently curved and cannot lie in a flat plane.

  20. A parametric study of cut-off corrugated surface properties

    NASA Technical Reports Server (NTRS)

    Mentzer, C. A.; Peters, L., Jr.

    1973-01-01

    Corrugated horns involve a junction between the corrugated surface and a conducting groundplane. Proper horn design requires an understanding of the electromagnetic properties of the corrugated surface and this junction. Therefore, an integral equation solution has been used to study the influence of corrugation density and shape on the power loss. Surface current, and the scattering from a groundplane-corrugated surface junction. Both square and vee shape corrugations have been considered over the range of corrugation depths where the surface acts as a cut-off corrugated surface.

  1. Nonlinear finite element modeling of corrugated board

    Treesearch

    A. C. Gilchrist; J. C. Suhling; T. J. Urbanik

    1999-01-01

    In this research, an investigation on the mechanical behavior of corrugated board has been performed using finite element analysis. Numerical finite element models for corrugated board geometries have been created and executed. Both geometric (large deformation) and material nonlinearities were included in the models. The analyses were performed using the commercial...

  2. Corrugated Pipe as a Beam Dechirper

    SciTech Connect

    Bane, K.L.F.; Stupakov, G.; /SLAC

    2012-04-20

    We have studied the use of a metallic pipe with small corrugations for the purpose of passively dechirping, through its wakefield, a short, intense electron bunch. The corrugated pipe is attractive for this purpose because its wake: (i) has near maximal possible amplitude for a given aperture and (ii) has a relatively large oscillation wave length, even when the aperture is small. We showed how the corrugated structure can satisfy dechirping requirements encountered in the NGLS project at LBNL. We found that a linear chirp of -40 MeV/mm can be induced by an NGLS-like beam, by having it pass through a corrugated, metallic pipe of radius 3 mm, length 8.2 m, and corrugation parameters full depth 450 {mu}m and period 1000 {mu}m. This structure is about 15 times as effective in the role of dechirper as an S-band accelerator structure used passively.

  3. Effective characteristics of corrugated plates

    NASA Astrophysics Data System (ADS)

    Arkhangel'skii, A. F.; Gorbachev, V. I.

    2007-06-01

    Corrugated plates are widely used in modern constructions and structures, because they, in contrast to plane plates, possess greater rigidity. In many cases, such a plate can be modeled by a homogeneous anisotropic plate with certain effective flexural and tensional rigidities. Depending on the geometry of corrugations and their location, the equivalent homogeneous plate can also have rigidities of mutual influence. These rigidities allow one to take into account the influence of bending moments on the strain in the midplane and, conversely, the influence of longitudinal strains on the plate bending [1]. The behavior of the corrugated plate under the action of a load normal to the midsurface is described by equations of the theory of flexible plates with initial deflection. These equations form a coupled system of nonlinear partial differential equations with variable coefficients [2]. The dependence of the coefficients on the coordinates is determined by the corrugation geometry. In the case of a plate with periodic corrugation, the coefficients significantly vary within one typical element and depend on the values of local variables determined in each of the typical elements. There is a connection between the local and global variables, and therefore, the functions of local coordinates are simultaneously functions of global coordinates, which are sometimes called rapidly oscillating functions [3]. One of the methods for solving the equations with rapidly oscillating coefficients is the asymptotic method of small geometric parameter. The standard procedure of this method usually includes preparatory stages. At the first stage, as a rule, a rectangular periodicity cell is distinguished to be a typical element. At the second stage, the scale of global coordinates is changed so that the rectangular structure periodicity cells became square cells of size l × l. The third stage consists in passing to the dimensionless global coordinates relative to the plate

  4. Mechanical Analysis of Trapezoidal Corrugated Composite Skins

    NASA Astrophysics Data System (ADS)

    Ghabezi, P.; Golzar, M.

    2013-08-01

    Using of the corrugated skins and morphing technology is a good idea to provide the desired performance and improve aerodynamic efficiency. Corrugated structures and skins are flexible in the direction of corrugation and stiff in the transverse direction. In this paper a simple analytical model for the effective stiffness of the trapezoidal corrugated composites is developed in symmetrical and unsymmetrical lay-up. The elongation and effective stiffness in longitudinal and transverse directions of trapezoidal corrugated skins and flat composites are extracted using strain energy and Castiglione's theorem. Various dimensions of trapezoidal element for unidirectional and plain woven fabrics of E-glass/Epoxy are investigated. Trapezoidal corrugated composites were modelled by commercial FEM software ABAQUS and compared to analytical model. Analytical model is validated by experimental results from bending and tensile tests. Finally, load-displacement curves in the tensile and bending tests are studied and their different stages of behavior are identified. Results of FEM, experimental and analytical simulation show that how the corrugated composite skins can afford obviously larger deformation than the flat one and they are good solution to use in the morphing applications.

  5. Corrugated pipe adhesive applicator apparatus

    DOEpatents

    Shirey, R.A.

    1983-06-14

    Apparatus for coating selected portions of the troughs of a corrugated pipe with an adhesive includes a support disposed within the pipe with a reservoir containing the adhesive disposed on the support. A pump, including a spout, is utilized for supplying the adhesive from the reservoir to a trough of the pipe. A rotatable applicator is supported on the support and contacts the trough of the pipe. The applicator itself is sized so as to fit within the trough, and contacts the adhesive in the trough and spreads the adhesive in the trough upon rotation. A trough shield, supported by the support and disposed in the path of rotation of the applicator, is utilized to prevent the applicator from contacting selected portions of the trough. A locator head is also disposed on the support and provides a way for aligning the spout, the applicator, and the trough shield with the trough. 4 figs.

  6. Corrugated pipe adhesive applicator apparatus

    DOEpatents

    Shirey, Ray A.

    1983-06-14

    Apparatus for coating selected portions of the troughs of a corrugated pipe within an adhesive includes a support disposed within the pipe with a reservoir containing the adhesive disposed on the support. A pump, including a spout, is utilized for supplying the adhesive from the reservoir to a trough of the pipe. A rotatable applicator is supported on the support and contacts the trough of the pipe. The applicator itself is sized so as to fit within the trough, and contacts the adhesive in the trough and spreads the adhesive in the trough upon rotation. A trough shield, supported by the support and disposed in the path of rotation of the applicator, is utilized to prevent the applicator from contacting selected portions of the trough. A locator head is also disposed on the support and provides a way for aligning the spout, the applicator, and the trough shield with the trough.

  7. Truss-core corrugation for compressive loads

    NASA Technical Reports Server (NTRS)

    Davis, Randall C. (Inventor); Jackson, Robert (Inventor)

    1988-01-01

    A corrugated panel structure for supporting compressive loads is described which includes curved cap strips separated by truss-core web segments. The truss-core web segments are formed from first and second flat panels with a corrugated filler in between them. The corrugated filler extends in the direction of the compressive load. As a result, all components of the panel structure have a compressive load carrying capability resulting in a high strength-to-weight ratio when the compressive load is limiting. Application to rocket and aircraft structures is suggested.

  8. The characterization of tandem and corrugated wings

    NASA Astrophysics Data System (ADS)

    Lian, Yongsheng; Broering, Timothy; Hord, Kyle; Prater, Russell

    2014-02-01

    Dragonfly wings have two distinct features: a tandem configuration and wing corrugation. Both features have been extensively studied with the aim to understand the superior flight performance of dragonflies. In this paper we review recent development of tandem and corrugated wing aerodynamics. With regards to the tandem configuration, this review will focus on wing/wing and wing/vortex interactions at different flapping modes and wing spacing. In addition, the aerodynamics of tandem wings under gusty conditions will be reviewed and compared with isolated wings to demonstrate the gust resistance characteristics of flapping wings. Regarding corrugated wings, we review their structural and aerodynamic characteristics.

  9. Truss-core corrugation for compressive loads

    NASA Astrophysics Data System (ADS)

    Davis, Randall C.; Jackson, Robert

    1988-09-01

    A corrugated panel structure for supporting compressive loads is described which includes curved cap strips separated by truss-core web segments. The truss-core web segments are formed from first and second flat panels with a corrugated filler in between them. The corrugated filler extends in the direction of the compressive load. As a result, all components of the panel structure have a compressive load carrying capability resulting in a high strength-to-weight ratio when the compressive load is limiting. Application to rocket and aircraft structures is suggested.

  10. Corrugated cover plate for flat plate collector

    DOEpatents

    Hollands, K. G. Terry; Sibbitt, Bruce

    1978-01-01

    A flat plate radiant energy collector is providing having a transparent cover. The cover has a V-corrugated shape which reduces the amount of energy reflected by the cover away from the flat plate absorber of the collector.

  11. Molecular Spectroscopy at Corrugated Metal Surfaces

    DTIC Science & Technology

    1988-10-01

    the authors, with emphasis on the effects due to surface corrugations. Examples which illustrate possible applications of such studies in the areas of surface photochemistry and heterogeneous catalysis are also discussed.

  12. Method and apparatus for corrugating strips

    DOEpatents

    Day, J.R.; Curtis, C.H.

    1981-10-27

    The invention relates to a method and a machine for transversely corrugating a continuous strip of metallic foil. The product foil comprises a succession of alternately disposed corrugations, each defining in a cross section, a major segment of a circle. The foil to be corrugated is positioned to extend within a vertical passage in the machine. The walls of the passage are heated to promote the desired deformation of the foil. Foil-deforming rollers are alternately passed obliquely across the passage to respectively engage transverse sections of the foil. The rollers and their respective section of deformed foil comprise a stacked assembly which is moved incrementally through the heated passageway. As the assembly emerges from the passageway, the rollers spill from the corrugated foil and are recovered for re-use.

  13. Method and apparatus for corrugating strips

    DOEpatents

    Day, Jack R.; Curtis, Charles H.

    1983-01-01

    The invention relates to a method and a machine for transversely corrugating a continuous strip of metallic foil. The product foil comprises a succession of alternately disposed corrugations, each defining in cross section, a major segment of a circle. The foil to be corrugated is positioned to extend within a vertical passage in the machine. The walls of the passage are heated to promote the desired deformation of the foil. Foil-deforming rollers are alternately passed obliquely across the passage to respectively engage transverse sections of the foil. The rollers and their respective section of deformed foil comprise a stacked assembly which is moved incrementally through the heated passageway. As the assembly emerges from the passageway, the rollers spill from the corrugated foil and are recovered for re-use.

  14. RF Pulse Compression Using Helically Corrugated Waveguides

    NASA Astrophysics Data System (ADS)

    MacInnes, P.; Ronald, K.; Burt, G.; Cross, A. W.; Young, A. R.; Phelps, A. D. R.; Konoplev, I. V.; He, W.; Samsonov, S. V.; Bratman, V. L.; Denisov, G. G.

    2006-01-01

    This paper describes the use of a helically corrugated waveguide as a dispersive medium for microwave pulse compression. The helically corrugated waveguide has a large variation of group velocity with frequency, but in a region where the group velocity remains large. Therefore this compressor does not suffer from reflections associated with cut-off scenarios at frequencies close to its operating regime and may be used in conjunction with high power wideband tunable microwave sources and amplifiers.

  15. Corrugated QWIP for Tactical Army Applications

    DTIC Science & Technology

    2008-12-01

    1 CORRUGATED QWIP FOR TACTICAL ARMY APPLICATIONS David. P. Forrai, Darrel W. Endres L-3 Communications Cincinnati Electronics Mason, OH 45040...Directorate (NVESD) have been developing the corrugated quantum well infrared photodetector (C- QWIP ) technology for applications in tactical LWIR...imaging. The C- QWIP was invented at ARL and shows promise to overcome some of the limitations in commercially available QWIPs . The C- QWIP uses micro

  16. Evolutionary design of corrugated horn antennas

    NASA Technical Reports Server (NTRS)

    Hoorfar, F.; Manshadi, V.; Jamnejad, A.

    2002-01-01

    An evolutionary progranirnitzg (EP) algorithm is used to optimize pattern of a corrugated circularhorn subject to various constraints on return loss and antenna beamwidth and pattern circularity and low crosspolarization. The EP algorithm uses a Gaussian mutation operator. Examples on design synthesis of a 45 section corrugated horn, with a total of 90 optimization parameters, are presented. The results show excellent and efficient optimization of the desired horn parameters.

  17. Evolutionary design of corrugated horn antennas

    NASA Technical Reports Server (NTRS)

    Hoorfar, F.; Manshadi, V.; Jamnejad, A.

    2002-01-01

    An evolutionary progranirnitzg (EP) algorithm is used to optimize pattern of a corrugated circularhorn subject to various constraints on return loss and antenna beamwidth and pattern circularity and low crosspolarization. The EP algorithm uses a Gaussian mutation operator. Examples on design synthesis of a 45 section corrugated horn, with a total of 90 optimization parameters, are presented. The results show excellent and efficient optimization of the desired horn parameters.

  18. High frequency scattering from corrugated stratified cylinders

    NASA Technical Reports Server (NTRS)

    Sarabandi, Kamal; Ulaby, Fawwaz T.

    1991-01-01

    Interest in applying radar remote sensing for the study of forested areas led to the development of a model for scattering from corrugated stratified dielectric cylinders. The model is used to investigate the effect of bark and its roughness on scattering from tree trunks and branches. The outer layer of the cylinder (bark) is assumed to be a low-loss dielectric material and to have a regular (periodic) corrugation pattern. The inner layers are treated as lossy dielectrics with smooth boundaries. A hybrid solution based on the moment method and the physical optics approximation is obtained. In the solution, the corrugations are replaced with polarization currents that are identical to those of the local tangential periodic corrugated surface, and the stratified cylinder is replaced with equivalent surface currents. New expressions for the equivalent physical-optics currents are used which are more convenient than the standard ones. It is shown that the bark layer and its roughness both reduce the radar cross-section. It is also demonstrated that the corrugations can be replaced by an equivalent anisotropic layer.

  19. Wetting and electrowetting on corrugated substrates

    NASA Astrophysics Data System (ADS)

    Wang, Zhanlong; Zhao, Ya-Pu

    2017-06-01

    Wetting and electrowetting (EW) on corrugated substrates are studied experimentally and theoretically in this paper. On corrugated substrates, because of the anisotropy of surface morphology, the droplet shows an elliptical shape and the spreading velocities in different directions are different. Spreading of a droplet is usually controlled not only by the surface tensions but also by hemi-wicking. Our experimental results indicated that liquids along the grooves propagate much faster than those in the direction vertical to the grooves. However, spreading in both directions obeys the same scaling law of l ˜t4 /5. EW on corrugated substrates reveals some differences with that on smooth surfaces. The change of contact angles with an applied voltage follows a linear relationship in two stages instead of the smooth curve on flat surfaces. There exists a critical voltage which divides the two stages. The transition of a droplet from the Cassie state to the Wenzel state on corrugated substrates was also discussed. The extended EW equation was derived with the free energy minimization approach, and the anisotropic factor was introduced. From the extended equation, it is found that EW is affected by the anisotropic factor significantly. For the smooth surfaces, the extended EW equation will degenerate to the classical Lippmann-Young equation. Our research may help us to understand the wetting and EW of droplets on corrugated substrates and assist in their design for practical applications.

  20. Corrugated plasmonic cavity for enhanced intersubband photodetection

    NASA Astrophysics Data System (ADS)

    Men, Chuanling; Qu, Ri; Cao, Jun; Yu, Haochi; Gou, Peng; Zou, Yuexin; Yang, Le; Qian, Jie; Zhao, Ziyi; Xu, Jie; An, Zhenghua

    2017-06-01

    We study the optical properties of a corrugated plasmonic cavity consisting of a perforated metal film and a flat metal sheet separated by a semiconductor spacer. Corrugation enhances dramatically the coupling between the propagating surface plasmon and the Fabry-Perot mode and induces Rabi-like splitting forming bright bonding and dark anti-bonding modes. The anti-bonding mode exhibits considerably higher volume-averaged field enhancement factors (˜16.5 for E-field and ˜14.1 for Ez-component) than its bonding counterpart as well as a very high polarization conversion ratio (˜85.5%) from transverse electric to transverse magnetic waves. These characteristics make the corrugation induced anti-bonding mode particularly suitable for semiconductor quantum well intersubband photodetectors. Our work may provide a general guideline to the design of metamaterial-coupled intersubband hybrid devices for practical applications.

  1. Assessment of rail long-pitch corrugation

    NASA Astrophysics Data System (ADS)

    Valehrach, Jan; Guziur, Petr; Riha, Tomas; Plasek, Otto

    2017-09-01

    The paper focuses on defects of the running surface of the rail, namely the rail corrugation defect and specifically long-pitch corrugation in curves of small radii. These defects cause a shorter life of the rails, greater maintenance costs and increase the noise and vibration pollution. Therefore, it is very important to understand the formation and development of the imperfection of the rails. In the paper, various sections of railway tracks in the Czech Republic are listed, each of them completed with comparison of defect development, the particular track superstructure, rolling stock, axle load, traffic load etc. Based on performed measurements, defect development has been proved as different on sections with similar (or even same) parameters. The paper assumes that a train velocity is the significant circumstance for defect development rates. Assessment of track section with under sleeper pads, which are expected to be the one of the possible ways to suppress the corrugation defect development, is included in evaluation.

  2. Graphene plasmon propagation on corrugated silicon substrates.

    PubMed

    Kong, Xiang-Tian; Bai, Bing; Dai, Qing

    2015-01-01

    The scheme of graphene on a silicon substrate is potentially compatible to the microelectronic technology. But the maintained plasmons have considerable ohmic loss because of silicon's large permittivity. We introduce air grooves in the silicon surface to reduce the optical thickness of substrate and hence decrease the propagation loss. The properties of graphene plasmons on the corrugated substrates are numerically investigated, in terms of the photon frequency and the geometrical parameters of the corrugated layer, considering both ohmic loss and scattering loss. The plasmons propagation lengths for the corrugated substrates can exceed twice of those for flat silicon in a broadband in mid-infrared. This study may be useful for designing of compact mid-infrared waveguides based on graphene for future photonic integrated circuits.

  3. Ultrasonic geometrical characterization of periodically corrugated surfaces.

    PubMed

    Liu, Jingfei; Declercq, Nico F

    2013-04-01

    Accurate characterization of the characteristic dimensions of a periodically corrugated surface using ultrasonic imaging technique is investigated both theoretically and experimentally. The possibility of accurately characterizing the characteristic dimensions is discussed. The condition for accurate characterization and the quantitative relationship between the accuracy and its determining parameters are given. The strategies to avoid diffraction effects instigated by the periodical nature of a corrugated surface are also discussed. Major causes of erroneous measurements are theoretically discussed and experimentally illustrated. A comparison is made between the presented results and the optical measurements, revealing acceptable agreement. This work realistically exposes the capability of the proposed ultrasonic technique to accurately characterize the lateral and vertical characteristic dimensions of corrugated surfaces. Both the general principles developed theoretically as well as the proposed practical techniques may serve as useful guidelines to peers.

  4. 40 CFR 246.202 - Corrugated container recovery.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Corrugated container recovery. 246.202... SEPARATION FOR MATERIALS RECOVERY GUIDELINES Requirements and Recommended Procedures § 246.202 Corrugated container recovery....

  5. 40 CFR 246.202 - Corrugated container recovery.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Corrugated container recovery. 246.202... SEPARATION FOR MATERIALS RECOVERY GUIDELINES Requirements and Recommended Procedures § 246.202 Corrugated container recovery....

  6. Radio-Absorbing Nanocoatings on Corrugated Surfaces

    NASA Astrophysics Data System (ADS)

    Antipov, V. B.; Potekaev, A. I.; Vorozhtsov, A. B.; Melentyev, S. V.; Tsyganok, Yu. I.

    2016-12-01

    The feasibility of producing protective radio-absorbing shielding materials on the basis of differently shaped surfaces with nanostructured coatings is investigated. Combinations of special nanostructured materials and technical solutions for the shape of the absorbing surface were tested, in order to create efficient nanocoatings. It is shown that the coatings of interest that meet the requirements of low reflection and high attenuation of transmitted radiation combined with low coating thickness can be developed, using corrugated surfaces. Corrugated chicken egg-packing cell samples with nanostructured carbon coatings were examined and found to allow for effective shielding of electromagnetic radiation and to exhibit minimum reflection coefficients as compared to construction materials.

  7. Dynamic response of clamped corrugated sandwich plates subjected to underwater impulsive loads

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Zhang, Wei; Ye, Nan; Li, Dacheng

    2017-01-01

    Corrugated sandwich plates are widely used in marine industry because such plates have high strength-to-weight ratios and blast resistance. The laboratory-scaled fluid-structure interaction experiments are performed to demonstrate the shock resistance of corrugated sandwich plates by quantifying the permanent transverse deflection at mid-span of the plates as a function of impulsive loadings per areal mass. Sandwich structures with 6mm-thick 3003 H18 aluminum corrugated core and 5A06 face sheets subjected to underwater impulsive loadings are studied experimentally in this paper. The dynamic deformations of plates are captured with the the 3D digital imaging correlation method (DIC). The results affirm the peak deflection during the processes of dynamic deformation and the residual maximum deflection for post-mortem plates show a linear trend with the impulses per areal mass, and show sensitivity to the change of impulses. Inhomogeneous deformation for corrugated sandwich plates are show uneven rather than the perfect parabolic shapes reported in previous studies. With the increasing of intensities for impulsive loadings, the failure modes can be observed more complicated from the initial plastic deformation to debonding and crack. This paper provides valid data to quantify the peak deflection, residual deflection and failure modes as functions of impulses and geometric parameters in the future work.

  8. Influence of corrugation shape in steel bars ductility used on reinforced concrete

    NASA Astrophysics Data System (ADS)

    Hortigón, B.; Nieto, E. J.; Fernández, F.; Hernández, O.

    2012-04-01

    Necking process stress and strain analysis, which is key to determine the plastic flow evolution in finite deformation, has been widely studied and applied to a number of materials based on the theories established by Davidenkov-Spiridnova and Bridgman in the 40's decade. These theories envolve from the study of necking geometry in fracture. In this paper, we develop an exhaustive experimental analysis of the stress and strain field in the necking process, applied to concrete bars and mechanized samples with similar features, in order to compare the results with the ones given by the theories listed above and to look for the corrugation influence in the material's plastic behavior.

  9. Optimum fiber distribution in singlewall corrugated fiberboard

    Treesearch

    Millard W. Johnson; Thomas J. Urbanik; William E. Denniston

    1979-01-01

    Determining optimum distribution of fiber through rational design of corrugated fiberboard could result in significant reductions in fiber required to meet end-use conditions, with subsequent reductions in price pressure and extension of the softwood timber supply. A theory of thin plates under large deformations is developed that is both kinematically and physically...

  10. Operating experience firing waxed corrugated cardboard waste

    SciTech Connect

    McBurney, B.

    1995-09-01

    Georgia-Pacific operates a corrugated packaging facility in Doraville, Georgia which a suburb of Atlanta. The plant processes bulk brown paper into corrugated sheets for corrugated packaging. The plant`s process and building heat requires approximately 15,000 PPH steam at 150 psig which was supplied by a natural gas fired package boiler. The mill disposed of the cardboard trimmings and waste in a nearby landfill at a disposal cost of several thousand dollars per month. In 1992, the mill recognized that the landfill would close in several years which would result in a significant increase in monthly cardboard waste disposal costs. Therefore, the mill sought an alternate yet economical solution for waste disposal. After evaluating several different alternatives including recycling, the mill installed a boiler system designed to fire the waxed corrugated cardboard waste (WCW) as both a solution for disposal of this waste and as an alternate source of boiler fuel. This paper reviews plant design, operating performance and maintenance history.

  11. Natural vibrations of corrugated orthotropic shells of revolution

    NASA Astrophysics Data System (ADS)

    Vatul'yan, K. A.; Makarov, S. S.; Ustinov, Yu. A.

    2016-11-01

    The torsional and longitudinal-flexural vibrations of corrugated orthotropic shells are investigated. Relations, including the equations of motion in forces and moments and Hooke's relations, are obtained using the Kirchhoff-Love hypotheses. The influence of the geometric parameters of the shell (corrugation amplitude and length) on the eigenfrequencies and natural vibrations modes is studied for fixed-end shells. It is found that during torsional vibrations, increasing the corrugation amplitude and increasing the number of corrugations leads to a decrease in the resonant frequencies. In the case of torsional and longitudinal-flexural vibrations, the influence of the corrugation amplitude on the natural vibration modes is investigated.

  12. Pressure Oscillating Flow in Corrugated Parallel Channel

    NASA Astrophysics Data System (ADS)

    Wei, Yu-Fei; Wang, Hai-Jun; Jian, Yong-Jun

    2016-12-01

    The approximate analytical solution of velocity is presented for incompressible and viscous fluid driven by the oscillation of the periodic pressure, between two slit parallel plates with corrugated walls by employing perturbation method. The corrugations of the two walls are described as periodic sinusoidal waves with small amplitude either in phase or half-period out of phase. Based on the analysis, we discuss the influence of the dimensionless parameters on velocity u± and mean velocity parameter ϕ± numerically, such as Reynolds number Re, nondimensional amplitude A of pressure gradient and wave number k. Supported by the National Natural Science Foundation of China under Grant No. 11472140, the Natural Science Foundation of Inner Mongolia Autonomous Region of China under Grant No. 2016MS0106, the Inner Mongolia Grassland Talent under Grant No. 12000-12102013

  13. Axial Crushing Characteristics of Circular Tubes with Radial Corrugation

    NASA Astrophysics Data System (ADS)

    Chen, Dai-Heng; Hattori, Kazuyuki; Ozaki, Shingo

    In this paper, the effect of radial corrugation on the crushing behaviors of circular tubes is studied by using the finite element method. The numerical analysis is carried out on two geometrically different types of corrugations, ”radial corrugated tube” (RCT) and ”radial corrugated tube with corners” (RCTC). To compare crushing behaviors of those of corrugated circular tubes, a non-corrugated circular tube (CT) is also analyzed. It is revealed that, in the crushing process, the crushing mode of RCT becomes more unstable than that of CT since the wavelength of the fold becomes long and the fold concentrates to the center of the wavelength. However, when the length and the diameter of the tubes are set to the same levels, RCT demonstrates good energy absorption characteristics. Further, it is shown that the compressive load and load efficiency of RCTC increases due to the corner part.

  14. 2. Elkmont, deck view of corrugated arched bridge. Great ...

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

    2. Elkmont, deck view of corrugated arched bridge. - Great Smoky Mountains National Park Roads & Bridges, Elkmont Vehicle Bridge, Spanning Little River at Elkmont Campground, Gatlinburg, Sevier County, TN

  15. 3. Elkmont, underside detail of corrugated arched bridge. Great ...

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

    3. Elkmont, underside detail of corrugated arched bridge. - Great Smoky Mountains National Park Roads & Bridges, Elkmont Vehicle Bridge, Spanning Little River at Elkmont Campground, Gatlinburg, Sevier County, TN

  16. Performance of zigzag corrugated furrows in Bolivia

    NASA Astrophysics Data System (ADS)

    Roldán Cañas, J.; Chipana, R.; Moreno-Pérez, M. F.; Chipana, G.

    2012-04-01

    In Bolivia, irrigation area is estimated in more than 250000 ha, being surface irrigation the most common method. In highland areas (Altiplano) and in interandean valleys, traditional and ancestral irrigation systems such as flood irrigation, contour furrows, zigzag corrugated furrows, suka kollus and irrigation by kanis, are the most important. In the case of very steep terrains and shallow soils, the zigzag corrugated irrigation method is very frequent. This irrigation method has been used for a long time but their low application efficiency and the shortage of water justify this work devoted to their characterization and to study their performance. The experimental study was conducted southeast of the city of La Paz in the community of Cebollino located at 2600 meters above sea level. Furrow characteristics vary in function of crop type and soil slope, so that the larger the slope the greater the separation between furrows. In our case, the crop chosen was the lettuce and the experimental plot had an area of 800 m2 with a slope ranging between 14 and 18%. Blocks of corrugated furrows were identified and experimental measures were made during each irrigation, once per week, in the central blocks to avoid border effects. To determine advance curves 15 stations were used spaced 18 m. At each station, advance and recession time and infiltration depth were measured. Inlet and outlet flow were controlled each 5 min. To calculate the reference evapotranspiration, the Hargraves-Samani equation was used. Due to the very high terrain slopes, the advance curve takes a linear form rather than the typical exponential form. This hinders the proper calculation of the parameters of the Kostiakov-Lewis equation used to determine the infiltrated depth values. The inlet flow range, along irrigation events, between 0.01 and 0.085 L/s due to the uncontrolled use of water in fields located upstream. The large variability of inflow flow difficult irrigation management especially in

  17. Lower San Fernando corrugated metal pipe failure

    SciTech Connect

    Bardet, J.P.; Davis, C.A.

    1995-12-31

    During the January 17, 1994, Northridge earthquake, a 2.4 m diameter corrugated metal pipe was subjected to 90 m of extensive lateral crushing failure at the Lower San Fernando Dam. The dam and outlet works were reconstructed after the 1971 San Fernando Earthquake. In 1994, the dam underwent liquefaction upstream of the reconstructed berm. The pipe collapsed on the west side of the liquefied zone and a large sinkhole formed over the drain line. The failure of this drain line provides a unique opportunity to study the seismic response of buried drains and culverts.

  18. The corrugated horn as an antenna range standard.

    NASA Technical Reports Server (NTRS)

    Caldecott, R.; Mentzer, C. A.; Peters, L., Jr.

    1973-01-01

    The corrugated horn is discussed as is a valuable tool for use in microwave pattern ranges. It has the properties of concentrated energy in the main beam, low backlobes, high efficiency, almost monotonic amplitude, and phase radiation patterns which make the corrugated horn useful for a source antenna in a pattern range and also as a possible standard antenna for calibration purposes.

  19. Dynamic tension testing equipment for paperboard and corrugated fiberboard

    Treesearch

    W. D. Godshall

    1965-01-01

    The objective of this work was to develop a method, the testing equipment, and the instrumentation with which dynamic stress-strain information may be obtained for paperboards and built-up corrugated fiberboards as used in corrugated fiberboard containers. Much information is available on the properties of these materials when subjected to static or low rates of...

  20. Corrugated Quantum Well Infrared Photodetectors and Arrays

    NASA Technical Reports Server (NTRS)

    Choi, K. K.; Chen, C. J.; Rohkinson, L. P.; Das, N. C.; Jhabvala, M.

    1999-01-01

    Quantum well infrared photodetectors (QWIPs) have many advantages in infrared detection, mainly due to the mature Ill-V material technology. The employment of the corrugation structure further advances the technology by providing a simple, yet efficient light-coupling scheme. A C-QWIP enjoys the same flexibility as a detector with intrinsic normal incident absorption. In this paper, we will discuss the utilities of C-QWIPs in different applications, including two-color detection and polarization-sensitive detection. Besides practical applications, C-QWIPs are also useful in detector characterization. They can be used for measuring the absorption coefficient of light propagating parallel to the layers under bias and providing information on the energy resolved photoconductive gain. These two quantities have never been measured before. Based on the corrugation design, we have made several modifications that further improve the detector sensitivity without increasing its complexity. Other than the C-QWIP structure, we also continue searching for other sensitive detector architectures. In a quantum grid infrared photodetector, 3-dimensional electron confinement can be achieved, with which the detector is able to absorb light in all directions. At the same time, the photoconductive gain can also be improved. We further improve the design using a blazed structure. All the experimental results are supported by a rigorous electromagnetic modal transmission-line theory developed especially for these types of structures. Preliminary thermal imaging using C-QWIP FPAs validates the advantages of the present approach.

  1. Water electrolyte transport through corrugated carbon nanopores.

    PubMed

    Moghimi Kheirabadi, A; Moosavi, A

    2014-07-01

    We investigate the effect of wall roughness on water electrolyte transport characteristics at different temperatures through carbon nanotubes by using nonequilibrium molecular dynamics simulations. Our results reveal that shearing stress and the nominal viscosity increase with ion concentration in corrugated carbon nanotubes (CNTs), in contrast to cases in smooth CNTs. Also, the temperature increase leads to the reduction of shearing stress and the nominal viscosity at moderate degrees of wall roughness. At high degrees of wall roughness, the temperature increase will enhance radial movements and increases resistance against fluid motion. As the fluid velocity increases, the particles do not have enough time to fully adjust their positions to minimize system energy, which causes shearing stress and the nominal viscosity to increase. By increasing roughness amplitude or decreasing roughness wavelength, the shearing stress will increase. Synergistic effects of such parameters (wall roughness, velocity, ion concentration, and temperature) inside corrugated CNTs are studied and compared with each other. The molecular mechanisms are considered by investigating the radial density profile and the radial velocity profile of confined water inside modified CNT.

  2. Corrugated Quantum Well Infrared Photodetectors and Arrays

    NASA Technical Reports Server (NTRS)

    Choi, K. K.; Chen, C. J.; Rohkinson, L. P.; Das, N. C.; Jhabvala, M.

    1999-01-01

    Quantum well infrared photodetectors (QWIPs) have many advantages in infrared detection, mainly due to the mature Ill-V material technology. The employment of the corrugation structure further advances the technology by providing a simple, yet efficient light-coupling scheme. A C-QWIP enjoys the same flexibility as a detector with intrinsic normal incident absorption. In this paper, we will discuss the utilities of C-QWIPs in different applications, including two-color detection and polarization-sensitive detection. Besides practical applications, C-QWIPs are also useful in detector characterization. They can be used for measuring the absorption coefficient of light propagating parallel to the layers under bias and providing information on the energy resolved photoconductive gain. These two quantities have never been measured before. Based on the corrugation design, we have made several modifications that further improve the detector sensitivity without increasing its complexity. Other than the C-QWIP structure, we also continue searching for other sensitive detector architectures. In a quantum grid infrared photodetector, 3-dimensional electron confinement can be achieved, with which the detector is able to absorb light in all directions. At the same time, the photoconductive gain can also be improved. We further improve the design using a blazed structure. All the experimental results are supported by a rigorous electromagnetic modal transmission-line theory developed especially for these types of structures. Preliminary thermal imaging using C-QWIP FPAs validates the advantages of the present approach.

  3. Biased Brownian motion in extremely corrugated tubes

    NASA Astrophysics Data System (ADS)

    Martens, S.; Schmid, G.; Schimansky-Geier, L.; Hänggi, P.

    2011-12-01

    Biased Brownian motion of point-size particles in a three-dimensional tube with varying cross-section is investigated. In the fashion of our recent work, Martens et al. [Phys. Rev. E 83, 051135 (2011)] we employ an asymptotic analysis to the stationary probability density in a geometric parameter of the tube geometry. We demonstrate that the leading order term is equivalent to the Fick-Jacobs approximation. Expression for the higher order corrections to the probability density is derived. Using this expansion orders, we obtain that in the diffusion dominated regime the average particle current equals the zeroth order Fick-Jacobs result corrected by a factor including the corrugation of the tube geometry. In particular, we demonstrate that this estimate is more accurate for extremely corrugated geometries compared with the common applied method using a spatially-dependent diffusion coefficient D(x, f) which substitutes the constant diffusion coefficient in the common Fick-Jacobs equation. The analytic findings are corroborated with the finite element calculation of a sinusoidal-shaped tube.

  4. Corrugation Profile for the Quasioptical Polarization Separator

    NASA Astrophysics Data System (ADS)

    Koposova, E. V.; Lubyako, L. V.

    2014-07-01

    We consider and classify the regime of separation of two orthogonally polarized E and H waves by using a reflecting metal diffraction grating, which sends all the energy of an incident wave with one polarization to the specular order of diffraction, and that of an incident wave with the other polarization, to the (-1)st order of diffraction (in this case, the autocollimation regime is used). The conditions of existence of such a regime are studied in the simplest cases (generalization of the approach presented in [1, 2] to the case of a sinusoidal surface), along with the possibility to construct more complex (nonsinusoidal) corrugation profiles, for which the specified regime has certain advantages, e.g., a wider bandwidth. Examples of such profiles are presented. The studies are performed on the basis of numerical solution of the problem of diffraction of a plane electromagnetic wave by a perfectly conducting corrugated surface within the framework of the integral-equation method employing the authors' computer visualization code.

  5. Terahertz guided mode properties in an internally corrugated plasmonic waveguide

    NASA Astrophysics Data System (ADS)

    Islam, Maidul; Chowdhury, Dibakar Roy; Ahmad, Amir; Kumar, Gagan

    2017-08-01

    We discuss the terahertz surface plasmon propagation properties in a waveguide comprising of subwavelength scale internally corrugated V-shaped structures. The structures are assumed to be periodically arranged in a thin sheet of metal and ensure plasmonic response of the waveguide. We comprehensively examine the effect of internal corrugations on the plasmonic properties of the guided modes supported by the waveguide. The guided mode properties are found to vary with the internal corrugations of the structures. We observe that multimode propagation can be switched to a single mode as we increase the steps of internal corrugations. The findings are supported with a semi-analytical model that we employ specifically for our geometry. We also analyze the dispersion properties of the fundamental modes under the different steps of corrugations and calculate group velocity in order to understand the slow light behavior of the modes. The results are compared with the waveguides having V-grooves without any internal corrugations. Our study could be significant to understand the role of corrugations along the waveguide as well as within the structures and accordingly their applications in the active and passive plasmonic guided wave devices.

  6. Fatigue testing of corrugated and Teflon hoses

    NASA Technical Reports Server (NTRS)

    Benner, Steve M.; Swanson, Theodore D.; Costello, Frederick A.

    1990-01-01

    Single and two-phase heat transport systems for the thermal control of large space facilities require fluid lines that traverse joints and either rotate or move in some other manner. Flexible hoses are being considered as one means of traversing these joints. To test the resilience of flexible hoses to bending stress, a test assembly was constructed to determine the number of flexing cycles the hoses could withstand before losing their ability to maintain a constant pressure. Corrugated metal hoses and Teflon hoses were tested at different pressures with nitrogen gas. The metal hoses had lives ranging from 30,000 to 100,000 flexing cycles. But, even after 400,000 cycles, the Teflon hoses remained essentially intact, though some leakage in the convoluted Teflon is noted.

  7. Effective Thermal Conductivity of Corrugated Insulating Materials

    NASA Astrophysics Data System (ADS)

    Yamada, Etsuro; Kato, Masayasu; Tomikawa, Takayuki; Takahashi, Kaneko

    The effective thermal conductivity of corrugated insulating materials which are made by polypropylene or polycarbonate have been measured by employing steady state comparison method for several specimen having various thickness and specific weight. The thermal conductivity of them evaluated are also by using the thermal resistance models, and are compared with above measured values and raw materials' conductivity. The main results obtained in this paper are as follows: (1) In regard to the specimen in this paper, the effective thermal conductivity increases with increasing temperature, but the increasing rate of them is small. (2) There are considerable differences between the measured values and the predicted ones that are estimated by using the thermal resistance model in which heat flow by conduction only. This differences increase with increasing specimens' thickness. This difference become extinct by considering the coexistence heat flow of conduction and radiation in the air phase of specimen. (3) The thermal resistance of specimen increases linearly with increasing specimens' thickness.

  8. Fatigue testing of corrugated and Teflon hoses

    NASA Astrophysics Data System (ADS)

    Benner, Steve M.; Swanson, Theodore D.; Costello, Frederick A.

    Single and two-phase heat transport systems for the thermal control of large space facilities require fluid lines that traverse joints and either rotate or move in some other manner. Flexible hoses are being considered as one means of traversing these joints. To test the resilience of flexible hoses to bending stress, a test assembly was constructed to determine the number of flexing cycles the hoses could withstand before losing their ability to maintain a constant pressure. Corrugated metal hoses and Teflon hoses were tested at different pressures with nitrogen gas. The metal hoses had lives ranging from 30,000 to 100,000 flexing cycles. But, even after 400,000 cycles, the Teflon hoses remained essentially intact, though some leakage in the convoluted Teflon is noted.

  9. Demonstration of angle-dependent Casimir force between corrugations.

    PubMed

    Banishev, A A; Wagner, J; Emig, T; Zandi, R; Mohideen, U

    2013-06-21

    The normal Casimir force between a sinusoidally corrugated gold coated plate and a sphere was measured at various angles between the corrugations using an atomic force microscope. A strong dependence on the orientation angle of the corrugation is found. The measured forces were found to deviate from the proximity force approximation and are in agreement with the theory based on the gradient expansion including correlation effects of geometry and material properties. We analyze the role of temperature. The obtained results open new opportunities for control of the Casimir effect in micromechanical systems.

  10. Thermal stability of corrugated epitaxial graphene grown on Re(0001).

    PubMed

    Miniussi, E; Pozzo, M; Baraldi, A; Vesselli, E; Zhan, R R; Comelli, G; Menteş, T O; Niño, M A; Locatelli, A; Lizzit, S; Alfè, D

    2011-05-27

    We report on a novel approach to determine the relationship between the corrugation and the thermal stability of epitaxial graphene grown on a strongly interacting substrate. According to our density functional theory calculations, the C single layer grown on Re(0001) is strongly corrugated, with a buckling of 1.6 Å, yielding a simulated C 1s core level spectrum which is in excellent agreement with the experimental one. We found that corrugation is closely knit with the thermal stability of the C network: C-C bond breaking is favored in the strongly buckled regions of the moiré cell, though it requires the presence of diffusing graphene layer vacancies.

  11. Light scattering by surface acoustic waves on corrugated metal surfaces

    SciTech Connect

    Robertson, W.M.; Grimsditch, M. ); Moretti, A.L.; Kaufman, R.G.; Hulse, G.R. ); Fullerton, E.; Schuller, I.K. )

    1990-03-15

    We report the results of a Brillouin-scattering study of corrugated Ag surfaces. The corrugation plays a dramatic role in the wave-vector--selection rules governing coupling to surface phonons, and this effect is substantially different when the effective wave vector of the surface corrugation is collinear or perpendicular to the scattering plane. In processes that involve the grating wave vector, we show that the coupling mechanism between light and phonons is governed by surface plasmons which introduce a new scattering interaction with unusual polarization features in the Brillouin-scattering process.

  12. Diverse corrugation pattern in radially shrinking carbon nanotubes

    SciTech Connect

    Shima, Hiroyuki; Sato, Motohiro; Iiboshi, Kohtaroh; Ghosh, Susanta; Arroyo, Marino

    2010-08-15

    Stable cross sections of multiwalled carbon nanotubes subjected to electron-beam irradiation are investigated in the realm of the continuum mechanics approximation. The self-healing nature of sp{sup 2} graphitic sheets implies that selective irradiation of the outermost walls causes their radial shrinkage with the remaining inner walls undamaged. The shrinking walls exert high pressure on the interior part of nanotubes, yielding a wide variety of radial-corrugation patterns (i.e., circumferentially wrinkling structures) in the cross section. All corrugation patterns can be classified into two deformation phases for which the corrugation amplitudes of the innermost wall differ significantly.

  13. Laser-Driven Corrugation Instability of Liquid Metal Surfaces

    NASA Astrophysics Data System (ADS)

    Keilmann, Fritz

    1983-12-01

    During intense CO2-laser irradiation deep corrugations build up on liquid metals such as Hg, In, Sn, Al, and Pb. Spacing, orientation, growth, and decay of the corrugations are studied, by visible light diffraction; support is found for a model of stimulated scattering where the incident light parametrically decays into both the surface corrugation and a surface plasmon. Thermal evaporation supplies the nonlinearity. The instability provides polarization-dependent absorption and can be expected in laser-metalworking and laser-plasma situations.

  14. 15. Culvert and corrugated pipe with place of a thousand ...

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

    15. Culvert and corrugated pipe with place of a thousand drips in background looking S. - Great Smoky Mountains National Park Roads & Bridges, Roaring Fork Motor Nature Trail, Between Cherokee Orchard Road & U.S. Route 321, Gatlinburg, Sevier County, TN

  15. 7. DETAIL VIEW UNDER BRIDGE OF CORRUGATED STEEL, BEAMS, RODS, ...

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

    7. DETAIL VIEW UNDER BRIDGE OF CORRUGATED STEEL, BEAMS, RODS, AND ABUTMENT - Price River Bridge, Spanning Price River, 760 North Street in Carbonville, 1 mile northwest of Price, Carbonville, Carbon County, UT

  16. Prediction of sound reflection by corrugated porous surfaces.

    PubMed

    Allard, J-F; Dazel, O; Gautier, G; Groby, J-P; Lauriks, W

    2011-04-01

    The coupled mode (CM) and finite-element methods (FEMs) are developed and used to predict the acoustic reflection coefficient of a semi-infinite porous medium with closely spaced two-dimensional (2D) periodical corrugations. These methods are also applied to predict the reflection coefficient of a periodic array of porous corrugations installed on an acoustically rigid surface. It is shown that the predictions by the both methods agree closely. The reflection coefficient and Brewster angle of total refraction for the corrugated semi-infinite medium predicted with these methods are compared against that predicted by the Biot/Tolstoy/Howe/Twersky and extended Twersky models. A similar analysis is carried out for porous corrugations set on a rigid backing. The behavior of the reflection coefficient and the pole in the expression for the reflection coefficient located close to grazing incidence is studied.

  17. Evaluation of Buried, Concrete-Lined Corrugated Metal Pipe.

    DTIC Science & Technology

    rehabilitation measure, was also inspected. Based on this field study, concrete-lined, corrugated metal pipe appears to be an acceptable drainage product when...proper production and installation quality controls are used. Keywords: Concrete coatings, Drainage pipes.

  18. A comparative study of corrugated horn design by evolutionary techniques

    NASA Technical Reports Server (NTRS)

    Hoorfar, A.

    2003-01-01

    Here an evolutionary programming algorithm is used to optimize the pattern of a corrugated circular horn subject to various constraints on return loss, antenna beamwidth, pattern circularity, and low cross polarization.

  19. Cleaning process for corrugated aluminum electrical transmission line enclosure

    DOEpatents

    Bowman, Gary K.

    1984-07-24

    A process for preparing the interior of a corrugated pipe or sheath comprises the steps of placing a predetermined amount of a tumbling abrasive material into the sheath, and then rotating the sheath.

  20. 1. Elkmont vehicle bridge at Elkmont Campground, galvanized corrugated arch. ...

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

    1. Elkmont vehicle bridge at Elkmont Campground, galvanized corrugated arch. - Great Smoky Mountains National Park Roads & Bridges, Elkmont Vehicle Bridge, Spanning Little River at Elkmont Campground, Gatlinburg, Sevier County, TN

  1. A Wideband Profiled Corrugated Horn for Multichroic Applications

    NASA Technical Reports Server (NTRS)

    Zeng, Lingzhen; Tong, Cheuk-yu Edward; Wollack, Edward J.; Chuss, David T.

    2015-01-01

    A wideband profiled corrugated feedhorn was developed for multichroic applications. This feedhorn features a return loss of better than -25 dB and cross polarization peaks below -30 dB, over a fractional bandwidth of greater than 50%. Its performance is close to that of the ring-loaded corrugated feedhorn; however, the design presented is much easier to fabricate at millimeter wavelengths.

  2. Stylus type MEMS texture sensor covered with corrugated diaphragm

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Takashiro; Asao, Hideaki; Tanaka, Shuji

    2017-09-01

    In this paper, a stylus type MEMS texture sensor covered with a corrugated palylene diaphragm, which prevent debris from jamming into the sensor without significant degradation of sensitivity and bandwidth, was reported. A new fabrication process using a lost-foil method to make the corrugated diaphragm on a 3-axis piezoresistive force sensor at wafer level has been developed. The texture sensor could detect the surface microstructure as small as about 10 \

  3. Do Steel Bridges Prevent Rail Corrugations?

    NASA Astrophysics Data System (ADS)

    Meinke, Peter; Stephanides, Johannes

    2010-03-01

    Rail corrugations (germ. "Schlupfwellen") are wear pattern, which emerge during the transits of railway vehicles at narrow railway curves (R ≤ 250 m) and they are a menace to railway operators, especially if their railroad network exists in mountains. Therefore ÖBB started recently a research program "OBO" (Optimierter Bogenoberbau) for better understanding and avoidance of "Schlupfwellen", which is mainly experimentally oriented. As a representative test track was the extended famous narrow curve at the valley of Brixen close to Kitzbühl chosen, and two Measurement sites where there established, one embedded in the ballasted track bed and another one on a steel bridge, situated in this curve. Measuring the passing trains, a rearly astonishing fact was discovered: Whereas in the ballasted track all well known typical features occur (vibration, bending and torsion of the rail,…), which produce the wear created Schlupfwellen and the dedicated grumbling noise, the wheelsets run properly on the steel bridge track and pass "friendly" the associated curve segment! Dicussing the ascertained fact, it was realized that on many European steel bridges such phenomena happens! The paper ends assuming that a broad-band vibration of the rail heads upon the steel bridge reduces the friction coefficient in the wheel/rail contact area ("Flange oilers"). This can be the reason for the smooth travel at the bridge. This may also be the basis for a technical application to overcome the generation of Schlupfwellen?

  4. Finite-temperature Casimir force between perfectly metallic corrugated surfaces

    SciTech Connect

    Sarabadani, Jalal; Miri, MirFaez

    2011-09-15

    We study the Casimir force between two corrugated plates due to thermal fluctuations of a scalar field. For arbitrary corrugations and temperature T, we provide an analytical expression for the Casimir force, which is exact to second order in the corrugation amplitude. We study the specific case of two sinusoidally corrugated plates with corrugation wavelength {lambda}, lateral displacement b, and mean separation H. We find that the lateral Casimir force is F{sub l}(T,H)sin(2{pi}b/{lambda}). In other words, at all temperatures, the lateral force is a sinusoidal function of the lateral shift. In the limit {lambda}>>H, F{sub l}(T{yields}{infinity},H){proportional_to}k{sub B}TH{sup -4}{lambda}{sup -1}. In the opposite limit {lambda}<

  5. Directional and enhanced spontaneous emission with a corrugated metal probe

    NASA Astrophysics Data System (ADS)

    Shen, Hongming; Lu, Guowei; He, Yingbo; Cheng, Yuqing; Liu, Haitao; Gong, Qihuang

    2014-06-01

    A three-dimensional corrugated metal tapered probe with surface corrugated gratings at the tip apex is proposed and investigated theoretically, which leads to an obvious emission beaming effect of spontaneous emission from a single emitter near the probe. In contrast with conventional apertureless metal probes, where only the enhancement of an optical near-field is concerned, the corrugated probe is able to manipulate local excitation intensity and far-field emission direction simultaneously. The angular emission from a single dipole source, being placed close to the corrugated probe, falls into a cone with a maximum directivity angle of +/-11.6°, which improves the collection efficiency 25-fold. Such a probe simultaneously increases the localized field intensity to about twice as strong as the conventional bare tip. In addition, the radiation pattern is sensitive to the working wavelength and the dipole to tip-apex separation. These findings make a promising route to the development of plasmonic spontaneous emission manipulation based on corrugated tapered antenna--for instance, tip-enhanced spectroscopy, single-molecule sensing, and single-photon source .

  6. Aerodynamic Performances of Corrugated Dragonfly Wings at Low Reynolds Numbers

    NASA Astrophysics Data System (ADS)

    Tamai, Masatoshi; He, Guowei; Hu, Hui

    2006-11-01

    The cross-sections of dragonfly wings have well-defined corrugated configurations, which seem to be not very suitable for flight according to traditional airfoil design principles. However, previous studies have led to surprising conclusions of that corrugated dragonfly wings would have better aerodynamic performances compared with traditional technical airfoils in the low Reynolds number regime where dragonflies usually fly. Unlike most of the previous studies of either measuring total aerodynamics forces (lift and drag) or conducting qualitative flow visualization, a series of wind tunnel experiments will be conducted in the present study to investigate the aerodynamic performances of corrugated dragonfly wings at low Reynolds numbers quantitatively. In addition to aerodynamics force measurements, detailed Particle Image Velocimetry (PIV) measurements will be conducted to quantify of the flow field around a two-dimensional corrugated dragonfly wing model to elucidate the fundamental physics associated with the flight features and aerodynamic performances of corrugated dragonfly wings. The aerodynamic performances of the dragonfly wing model will be compared with those of a simple flat plate and a NASA low-speed airfoil at low Reynolds numbers.

  7. Aerothermodynamic Assessment of Corrugated Panel Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Brandon, H. J.; Britt, A. H.; Kipp, H. W.; Masek, R. V.

    1978-01-01

    The feasibility of using corrugated panels as a thermal protection system for an advanced space transportation vehicle was investigated. The study consisted of two major tasks: development of improved correlations for wind tunnel heat transfer and pressure data to yield design techniques, and application of the design techniques to determine if corrugated panels have application future aerospace vehicles. A single-stage-to-orbit vehicle was used to assess advantages and aerothermodynamic penalties associated with use of such panels. In the correlation task, experimental turbulent heat transfer and pressure data obtained on corrugation roughened surfaces during wind tunnel testing were analyzed and compared with flat plate data. The correlations and data comparisons included the effects of a large range of geometric, inviscid flow, internal boundary layer, and bulk boundary layer parameters in supersonic and hypersonic flow.

  8. Dynamic Stability of Crack Fronts: Out-Of-Plane Corrugations

    NASA Astrophysics Data System (ADS)

    Adda-Bedia, Mokhtar; Arias, Rodrigo E.; Bouchbinder, Eran; Katzav, Eytan

    2013-01-01

    The dynamics and stability of brittle cracks are not yet fully understood. Here we use the Willis-Movchan 3D linear perturbation formalism [J. Mech. Phys. Solids 45, 591 (1997)] to study the out-of-plane stability of planar crack fronts in the framework of linear elastic fracture mechanics. We discuss a minimal scenario in which linearly unstable crack front corrugations might emerge above a critical front propagation speed. We calculate this speed as a function of Poisson’s ratio and show that corrugations propagate along the crack front at nearly the Rayleigh wave speed. Finally, we hypothesize about a possible relation between such corrugations and the long-standing problem of crack branching.

  9. Equivalent models of corrugated laminates for morphing skins

    NASA Astrophysics Data System (ADS)

    Xia, Yuying; Friswell, Michael I.

    2011-03-01

    The design of the skins has been identified as a major issue for morphing aircraft wings. Corrugated laminates provide a good solution due to their extremely anisotropic behavior. However, the optimal design of a morphing aircraft requires simple models of the skins that may be incorporated into multi-disciplinary system models. This requires equivalent material models that retain the dependence on the geometric parameters of the corrugated skins. An analytical homogenization model, which could be used for any corrugation shape, is suggested in this paper. This method is based on a simplified geometry for a unit-cell and the stiffness properties of original sheet. This paper investigates such a modeling strategy and demonstrates its performance and potential.

  10. Mitigation of whistling in vertical corrugated pipes by liquid addition

    NASA Astrophysics Data System (ADS)

    van Eckeveld, A. C.; Westerweel, J.; Poelma, C.

    2017-09-01

    When a corrugated pipe is subject to a dry gas flow, high amplitude sound can be produced (so-called `whistling'). It was shown previously that liquid addition to corrugated pipe flow has the ability to reduce sound production. Small amounts of liquid are sufficient to mitigate whistling entirely. One of the mitigation mechanisms, cavity filling, is studied experimentally. Acoustic measurements are combined with a planar laser-induced fluorescence technique to measure the liquid accumulation in the cavities of a corrugated pipe. Using this technique, it is shown that the amount of filling of the cavities with liquid increases with increasing liquid injection rate and with reducing gas flow rate. The reduction in whistling amplitude caused by the liquid injection is closely related to the cavity filling. This indicates that the geometric alteration of the pipe wall, caused by the accumulation of liquid inside the cavities, is an important factor in the reduction in whistling amplitude.

  11. Numerical study of signal propagation in corrugated coaxial cables

    SciTech Connect

    Li, Jichun; Machorro, Eric A.; Shields, Sidney

    2017-01-01

    Our article focuses on high-fidelity modeling of signal propagation in corrugated coaxial cables. Taking advantage of the axisymmetry, the authors reduce the 3-D problem to a 2-D problem by solving time-dependent Maxwell's equations in cylindrical coordinates.They then develop a nodal discontinuous Galerkin method for solving their model equations. We prove stability and error analysis for the semi-discrete scheme. We we present our numerical results, we demonstrate that our algorithm not only converges as our theoretical analysis predicts, but it is also very effective in solving a variety of signal propagation problems in practical corrugated coaxial cables.

  12. Corrugated capillary as THz Cherenkov Smith-Purcell radiator

    NASA Astrophysics Data System (ADS)

    Lekomtsev, K. V.; Aryshev, A. S.; Tishchenko, A. A.; Ponomarenko, A. A.; Sukharev, V. M.; Terunuma, N.; Urakawa, J.; Strikhanov, M. N.

    2016-07-01

    In this article we discussed Particle In Cell electromagnetic simulations and mechanical design of dielectric capillaries that produce THz Cherenkov Smith-Purcell radiation (ChSPR), arising when a femtosecond electron multi-bunch beam propagates through corrugated and non-corrugated dielectric capillaries with metallic radiation reflectors. We investigated the influence of the four-bunch beam on the SPR field spectrum and on the ChSPR power spectrum, and the influence of the non-central beam propagation on the ChSPR power spectrum. We also discussed the design and assembly of the capillaries, constructed as sets of cylindrical rings.

  13. Numerical study of signal propagation in corrugated coaxial cables

    SciTech Connect

    Li, Jichun; Machorro, Eric A.; Shields, Sidney

    2017-01-01

    Our article focuses on high-fidelity modeling of signal propagation in corrugated coaxial cables. Taking advantage of the axisymmetry, the authors reduce the 3-D problem to a 2-D problem by solving time-dependent Maxwell's equations in cylindrical coordinates.They then develop a nodal discontinuous Galerkin method for solving their model equations. We prove stability and error analysis for the semi-discrete scheme. We we present our numerical results, we demonstrate that our algorithm not only converges as our theoretical analysis predicts, but it is also very effective in solving a variety of signal propagation problems in practical corrugated coaxial cables.

  14. Finite element corroboration of buckling phenomena observed in corrugated boxes

    Treesearch

    Thomas J. Urbanik; Edmond P. Saliklis

    2003-01-01

    Conventional compression strength formulas for corrugated fiberboard boxes are limited to geometry and material that produce an elastic postbuckling failure. Inelastic postbuckling can occur in squatty boxes and trays, but a mechanistic rationale for unifying observed strength data is lacking. This study combines a finite element model with a parametric design of the...

  15. Strength and life criteria for corrugated fiberboard by three methods

    Treesearch

    Thomas J. Urbanik

    1997-01-01

    The conventional test method for determining the stacking life of corrugated containers at a fixed load level does not adequately predict a safe load when storage time is fixed. This study introduced multiple load levels and related the probability of time at failure to load. A statistical analysis of logarithm-of-time failure data varying with load level predicts the...

  16. A corrugated termination shock in pulsar wind nebulae?

    NASA Astrophysics Data System (ADS)

    Lemoine, Martin

    2016-08-01

    Successful phenomenological models of pulsar wind nebulae assume efficient dissipation of the Poynting flux of the magnetized electron-positron wind as well as efficient acceleration of the pairs in the vicinity of the termination shock, but how this is realized is not yet well understood. This paper suggests that the corrugation of the termination shock, at the onset of nonlinearity, may lead towards the desired phenomenology. Nonlinear corrugation of the termination shock would convert a fraction of order unity of the incoming ordered magnetic field into downstream turbulence, slowing down the flow to sub-relativistic velocities. The dissipation of turbulence would further preheat the pair population on short length scales, close to equipartition with the magnetic field, thereby reducing the initial high magnetization to values of order unity. Furthermore, it is speculated that the turbulence generated by the corrugation pattern may sustain a relativistic Fermi process, accelerating particles close to the radiation reaction limit, as observed in the Crab nebula. The required corrugation could be induced by the fast magnetosonic modes of downstream nebular turbulence; but it could also be produced by upstream turbulence, either carried by the wind or seeded in the precursor by the accelerated particles themselves.

  17. Laser Welded Corrugated Steel Panels in Industrial Applications

    NASA Astrophysics Data System (ADS)

    Kananen, M.; Mäntyjärvi, K.; Keskitalo, M.; Hietala, M.; Järvenpää, A.; Holappa, K.; Saine, K.; Teiskonen, J.

    Corrugated core steel panels are an effective way to reduce weight and increase stiffness of steel structures. In numerous applications, these panels have shown very promising commercial possibilities. This study presents the design, manufacturing and commercializing process for two practical examples: Case 1) a fly wheel cover for a diesel engine and Case 2) rotationally symmetrical panel for an electric motor. Test materials of various kinds were used for corrugated cores and skin plates: conventional low-carbon steel grade EN 10130 and ferritic stainless steel grade 1.4509 with plate the thicknesses of 0.5, 0.6 and 0.75 mm. To manufacture different kinds of corrugated core steel panels, flexible manufacturing tools and cost-effective processes are needed. The most important criterion for laser welding panels was the capability of forming tools for producing high quality geometry for the core. Laser welding assembly showed that the quality of the core in both studied cases was good enough for welding the lap joints properly. Developed panels have been tested in industrial applications with excellent feedback. If thickness of a corrugated panel structure is not a limiting issue, these panels are good solution on application where stiffness and lighter weight are required as well as vibrational aspect considered.

  18. Effective slip boundary conditions for sinusoidally corrugated surfaces

    NASA Astrophysics Data System (ADS)

    Guo, Lin; Chen, Shiyi; Robbins, Mark O.

    2016-11-01

    Molecular dynamics simulations are used to investigate the effective slip boundary condition for a simple fluid flowing over surfaces with one-dimensional sinusoidal roughness in the Wenzel state. The effective slip length is calculated as a function of the corrugation amplitude for flows along two principal orientations: transverse and longitudinal to the corrugation. Different atomic configurations, bent and stepped, are examined for strong and weak wall-fluid interactions and high and low wall densities. Molecular dynamics results for sparse bent surfaces quantitatively agree with continuum hydrodynamic predictions with a constant local slip length. Increasing the roughness amplitude reduces the effective slip length and the reduction is larger for transverse flow than longitudinal flow. Atomic effects become important for dense surfaces, because the local slip length varies with the local curvature and atomic spacing along the wall. These effects can be captured by applying a spatially varying boundary condition to the Navier-Stokes equations. Results for stepped surfaces are qualitatively different than continuum predictions, with the effect of corrugation rising linearly with corrugation amplitude rather than quadratically. There is an increased drag for transverse flow that is proportional to the density of step edges and lowers the slip length. Edges tend to increase the slip length for longitudinal flow because of order induced along the edges.

  19. OBLIQUE VIEW OF POWERHOUSE OFFICE AND CORRUGATED METALCLAD VEHICLE GARAGE ...

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

    OBLIQUE VIEW OF POWERHOUSE OFFICE AND CORRUGATED METAL-CLAD VEHICLE GARAGE AND FUEL PUMP. MAINTENANCE BUILDING IS AT RIGHT CENTER. 90mm lens - Tule River Hydroelectric Complex, CA Highway 190 at North Fork of Middle Fork of Tule River, Springville, Tulare County, CA

  20. Mechanical behavior of Kenaf/Epoxy corrugated sandwich structures

    NASA Astrophysics Data System (ADS)

    Bakhori, S.; Hassan, M. Z.; Daud, Y.; Sarip, S.; Rahman, N.; Ismail, Z.; Aziz, S. A.

    2015-12-01

    This study presents the response of kenaf/epoxy corrugated sandwich structure during quasi-static test. Force-displacements curves have been deducted to determine the deformation pattern and collapse behavior of the structure. Kenaf/epoxy sandwich structures skins fabricated by using hand layup technique and the corrugated core were moulded by using steel mould. Different thicknesses of corrugated core web with two sizes of kenaf fibers were used. The corrugated core is then bonded with the skins by using poly-epoxy resin and has been cut into different number of cells. The specimens then tested under tensile and compression at different constant speeds until the specimens fully crushed. Tensile tests data showed the structure can be considered brittle when it breaking point strain, ε less than 0.025. In compression test, the specimens fail due to dominated by stress concentration that initiated by prior cracks. Also, the specimens with more number of cells and thicker core web have higher strength and the ability to absorb higher energy.

  1. Design of a practical dental chair made of corrugated cardboard.

    PubMed

    Goldstein, C M

    1978-12-01

    Directions for the construction of a corrugated cardboard dental chair, useful for mobile clinics and community dentistry programs, are presented. The designers of the cardboard dental chair and I hope that it will be as useful to other members of our profession as it has been to the USC Mobile Dental Clinic.

  2. Bending of five-layer beams with crosswise corrugated main core

    SciTech Connect

    Magnucka-Blandzi, Ewa; Walczak, Zbigniew

    2015-03-10

    The subject of the study is one orthotropic thin-walled sandwich beam with trapezoidal core and two-layer facings. The outer layers of facings are flat, but inner layers are trapezoidal corrugated. The main core of the beam is also trapezoidal corrugated – in perpendicular direction to the corrugation of inner layers of facings. The beam is with lengthwise corrugated layers and crosswise corrugated main core. The mathematical and physical model of this beam is formulated, and also the field of displacements. The system of equilibrium equations is analytically derived using the energy method. The obtained solutions will be verified numerically (FEM)

  3. Optimization of photonics for corrugated thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Deparis, Olivier; Vigneron, Jean Pol; Agustsson, Otto; Decroupet, Daniel

    2009-11-01

    The amount of solar energy reaching the active (photovoltaic) layer in a thin-film solar cell can be increased by reducing the Fresnel reflection losses at the interfaces. By using corrugated interfaces (at the wavelength scale), adiabatic propagation of the electromagnetic radiation is achieved over a broad wavelength range throughout the structure, which leads to an increase in the light that is absorbed in the active layer and, ultimately, to the improvement of the photovoltaic conversion efficiency. In this article, we have considered the case of corrugated thin-film solar cell structures and we have studied theoretically the optimization of such structures from the point of view of photonics. The focus was put on periodic pyramidal interface corrugations because they were similar to those existing at the surface of corrugated transparent electrodes on which active layers can be deposited. Because of their technological importance, we chose to work with fluorine-doped tin oxide as front electrode material and with amorphous silicon as active material. Using an original three dimensional transfer matrix method, we solved the electromagnetic wave propagation problem in the general case of laterally periodic stratified media and we compared this solution with effective medium approximated solution. On the basis of typical pyramid sizes, we demonstrated, through numerical simulations, the optimization of the global light energy intake by means of corrugations of increasing complexity. The best structures were found to be based on pyramid arrays having subwavelength periods and aspect ratio values close to one. Typically, a pyramidal structure with base and height both equal to 300 nm led to a global energy intake equal to I =0.98 (integrated over the spectral range 400-710 nm), which represented a 24% improvement in comparison with the global energy intake of a planar structure (I =0.79).

  4. Test of superplastically formed corrugated aluminum compression specimens with beaded webs

    NASA Technical Reports Server (NTRS)

    Davis, Randall C.; Royster, Dick M.; Bales, Thomas T.; James, William F.; Shinn, Joseph M., Jr.

    1991-01-01

    Corrugated wall sections provide a highly efficient structure for carrying compressive loads in aircraft and spacecraft fuselages. The superplastic forming (SPF) process offers a means to produce complex shells and panels with corrugated wall shapes. A study was made to investigate the feasibility of superplastically forming 7475-T6 aluminum sheet into a corrugated wall configuration and to demonstrate the structural integrity of the construction by testing. The corrugated configuration selected has beaded web segments separating curved-cap segments. Eight test specimens were fabricated. Two specimens were simply a single sheet of aluminum superplastically formed to a beaded-web, curved-cap corrugation configuration. Six specimens were single-sheet corrugations modified by adhesive bonding additional sheet material to selectively reinforce the curved-cap portion of the corrugation. The specimens were tested to failure by crippling in end compression at room temperature.

  5. Corrugated Organic Light Emitting Diodes Using Low Tg Electron Transporting Materials.

    PubMed

    Peng, Cheng; Liu, Shuyi; Fu, Xiangyu; Pan, Zhenxing; Chen, Ying; So, Franky; Schanze, Kirk S

    2016-06-29

    A corrugated organic light emitting diode (OLED) with enhanced light extraction is realized by incorporating a corrugated composite electron transport layer (ETL) consisting of two ETLs with different glass transition temperatures. The morphology of the corrugated structure is characterized with atomic force microscopy. The results show that the corrugation can be controlled by the layer thicknesses and annealing temperature. Compared with the control planar device, the corrugated OLED shows a more than 35% enhancement in current efficiency from 31 cd/A to 43 cd/A and a 20% enhancement in external quantum efficiency from 10% to 12% at 100 cd/m(2). In addition, the corrugated OLED also has a greatly improved operational stability. The LT90 lifetime of a device operated at 1000 cd/m(2) is improved greater than 100-fold in the corrugated OLED.

  6. Geometrical investigations of the Casimir effect: Thickness and corrugation dependencies

    NASA Astrophysics Data System (ADS)

    Parashar, Prachi

    2011-12-01

    decompose the problem into two transverse scalar modes. In Chapter 3 we collect all the solutions for the scalar Green's functions for the planar and the cylindrical geometries, which are relevant for this dissertation. In Chapter 4 we derive the interaction energy between two dielectric slabs of finite thickness. Taking the thickness of the slabs to infinity leads to the Lifshitz results for the two infinite dielectric semi-spaces, while taking the dielectric permittivity to infinity gives the well-known Casimir energy between two perfect conductors. We then present a simple model to consider the thin-plate limit (taking the thickness of the slabs to zero) based on Drude-Sommerfeld free electron gas model, which modifies the plasma frequency of the material to include the finite size dependence. We get a non-vanishing result for the Lifshitz energy in the slab thickness going to zero limit. This is remarkable progress as it allows us to understand the infinitesimal thickness limit and opens a possibility of extending this model to apply it to graphene and other two dimensional surfaces. The Casimir and Casimir-Polder results in the perfect conductor limit give us the expected results. In Chapter 5 we study the lateral Casimir torque between two concentric corrugated cylinders described by delta-potentials, which interact through a scalar field. We derive analytic expressions for the Casimir torque for the case when the corrugation amplitudes are small in comparison to the corrugation wavelengths. We derive explicit results for the Dirichlet case, and exact results for the weak coupling limit, in the leading order. The results for the corrugated cylinders approach the corresponding expressions for the case of corrugated parallel plates in the limit of large radii of the cylinders (relative to the difference in their radii) while keeping the corrugation wavelength fixed. In Chapter 6 we calculate the lateral Casimir energy between corrugated parallel dielectric slabs of

  7. Design and manufacturing of skins based on composite corrugated laminates for morphing aerodynamic surfaces

    NASA Astrophysics Data System (ADS)

    Airoldi, Alessandro; Fournier, Stephane; Borlandelli, Elena; Bettini, Paolo; Sala, Giuseppe

    2017-04-01

    The paper discusses the approaches for the design and manufacturing of morphing skins based on rectangular-shaped composite corrugated laminates and proposes a novel solution to prevent detrimental effects of corrugation on aerodynamic performances. Additionally, more complex corrugated shapes are presented and analysed. The manufacturing issues related to the production of corrugated laminates are discussed and tests are performed to compare different solutions and to assess the validity of analytical and numerical predictions. The solution presented to develop an aerodynamically efficient skin consists in the integration of an elastomeric cover in the corrugated laminate. The related manufacturing process is presented and assessed, and a fully nonlinear numerical model is developed and characterized to study the behaviour of this skin concept in different load conditions. Finally, configurations based on combinations of individual rectangular-shaped corrugated panels are considered. Their structural properties are numerically investigated by varying geometrical parameters. Performance indices are defined to compare structural stiffness contributions in non-morphing directions with the ones of conventional panels of the same weight. Numerical studies also show that the extension of the concept to complex corrugated shapes may improve both the design flexibility and some specific performances with respect to rectangular shaped corrugations. The overall results validate the design approaches and manufacturing processes to produce corrugated laminates and indicate that the solution for the integration of an elastomeric cover is a feasible and promising method to enhance the aerodynamic efficiency of corrugated skins.

  8. Corrugated graphene layers for sea water desalination using capacitive deionization.

    PubMed

    Dahanayaka, Madhavi; Liu, Bo; Hu, Zhongqiao; Chen, Zhong; Law, Adrian Wing-Keung; Zhou, Kun

    2017-03-14

    The effect of the electric field and surface morphology of corrugated graphene (GE) layers on their capacitive deionization process is studied using molecular dynamics simulations. Deionization performances are evaluated in terms of water flow rate and ion adsorption and explained by analysing the water density distribution, radial distribution function and distribution of the ions inside the GE layers. The simulation results reveal that corrugation of GE layers reduces the water flow rate but largely enhances ion adsorption in comparison to the flat GE layers. Such enhancement is mainly due to the adsorption of ions on the GE layers due to the anchoring effect in the regions with wide interlayer distances. Moreover, it reveals that the entrance configuration of the GE layers also has a significant effect on the performance of deionization. Overall, the results from this study will be helpful in designing effective electrode configurations for capacitive deionization.

  9. Direct Acceleration of Electrons in a Corrugated Plasma Channel

    SciTech Connect

    Palastro, J. P.; Antonsen, T. M.; Morshed, S.; York, A. G.; Layer, B.; Aubuchon, M.; Milchberg, H. M.; Froula, D. H.

    2009-01-22

    Direct laser acceleration of electrons provides a low power tabletop alternative to laser wakefield accelerators. Until recently, however, direct acceleration has been limited by diffraction, phase matching, and material damage thresholds. The development of the corrugated plasma channel [B. Layer et al., Phys. Rev. Lett. 99, 035001 (2007)] has removed all of these limitations and promises to allow direct acceleration of electrons over many centimeters at high gradients using femtosecond lasers [A. G. York et al., Phys Rev. Lett 100, 195001 (2008), J. P. Palastro et al., Phys. Rev. E 77, 036405 (2008)]. We present a simple analytic model of laser propagation in a corrugated plasma channel and examine the laser-electron beam interaction. Simulations show accelerating gradients of several hundred MeV/cm for laser powers much lower than required by standard laser wakefield schemes. In addition, the laser provides a transverse force that confines the high energy electrons on axis, while expelling low energy electrons.

  10. Experimental results on microwave pulse compression using helically corrugated waveguide

    NASA Astrophysics Data System (ADS)

    McStravick, M.; Samsonov, S. V.; Ronald, K.; Mishakin, S. V.; He, W.; Denisov, G. G.; Whyte, C. G.; Bratman, V. L.; Cross, A. W.; Young, A. R.; MacInnes, P.; Robertson, C. W.; Phelps, A. D. R.

    2010-09-01

    The paper presents new results on the development of a method to generate ultrahigh-power short-microwave pulses by using a known principle of compression (reduction in pulse duration accompanying with increase in pulse amplitude) of a frequency-swept wave packet propagating through a dispersive medium. An oversized circular waveguide with helical-corrugations of its inner surface ensures an eigenwave with strongly frequency dependent group velocity far from cutoff. These dispersive properties in conjunction with high rf breakdown strength and low Ohmic losses make a helically corrugated waveguide attractive for increasing microwave peak power. The experiments performed at kilowatt power levels, demonstrate that an X-band microwave pulse of 80 ns duration with a 5% frequency sweep can be compressed into a 1.5 ns pulse having 25 times higher peak power by optimizing the frequency modulation of the input wave packet.

  11. Microwave radiation absorbers based on corrugated composites with carbon fibers

    NASA Astrophysics Data System (ADS)

    Bychanok, D. S.; Plyushch, A. O.; Gorokhov, G. V.; Bychanok, U. S.; Kuzhir, P. P.; Maksimenko, S. A.

    2016-12-01

    A complex analysis of the dependence of the absorption coefficient of polymer composites with nonmagnetic carbon inclusions on the real and imaginary parts of the complex permittivity, as well as on the material thickness is performed in frequency range 26-37 GHz. The composites containing 0.2 wt % of carbon fibers have been obtained. It has been experimentally found that the corrugation of the composite surface substantially increases the absorbability (from 63 to 92% at a frequency of 30 GHz and a thickness of 4.50 mm) upon a decrease in the sample mass (by 28%). A method has been proposed for calculating the absorptance of corrugated composites in the microwave range.

  12. Corrugated outer sheath gas-insulated transmission line

    DOEpatents

    Kemeny, George A.; Cookson, Alan H.

    1981-01-01

    A gas-insulated transmission line includes two transmission line sections each of which are formed of a corrugated outer housing enclosing an inner high-voltage conductor disposed therein, with insulating support means supporting the inner conductor within the outer housing and an insulating gas providing electrical insulation therebetween. The outer housings in each section have smooth end sections at the longitudinal ends thereof which are joined together by joining means which provide for a sealing fixed joint.

  13. Optimization of a corrugated stiffened composite panel under uniaxial compression

    NASA Technical Reports Server (NTRS)

    Agarwal, B. L.; Sobel, L. H.

    1973-01-01

    An approach of structural optimization has been used to optimize the weight of a simply supported, corrugated hat stiffened composite panel under uniaxial compression. The approach consists of the employment of nonlinear mathematical programming techniques to reach an optimum solution. Some simplifying assumptions are made in the stress analysis to obtain faster convergence to an optimum solution. With these simplifying assumptions the number of unknown design parameters is reduced to twelve.

  14. Flow Pressure Loss through Straight Annular Corrugated Pipes

    NASA Technical Reports Server (NTRS)

    Sargent, Joseph R.; Kirk, Daniel R.; Marsell, Brandon; Roth, Jacob; Schallhorn, Paul A.; Pitchford, Brian; Weber, Chris; Bulk, Timothy

    2016-01-01

    Pressure loss through annular corrugated pipes, using fully developed gaseous nitrogen representing purge pipes in spacecraft fairings, was studied to gain insight into a friction factor coefficient for these pipes. Twelve pipes were tested: four Annuflex, four Masterflex and two Titeflex with ¼”, 3/8”, ½” and ¾” inner diameters. Experimental set-up was validated using smooth-pipe and showed good agreement to the Moody diagram. Nitrogen flow rates between 0-200 standard cubic feet per hour were used, producing approximate Reynolds numbers from 300-23,000. Corrugation depth varied from 0.248 = E/D = 0.349 and relative corrugation pitch of 0.192 = P/D = 0.483. Differential pressure per unit length was measured and calculated using 8-9 equidistant pressure taps. A detailed experimental uncertainty analysis, including correlated bias error terms, is presented. Results show larger differential pressure losses than smooth-pipes with similar inner diameters resulting in larger friction factor coefficients.

  15. Measurements of terahertz radiation generated using a metallic, corrugated pipe

    DOE PAGES

    Bane, Karl; Stupakov, Gennady; Antipov, Sergey; ...

    2016-11-23

    Here, a method for producing narrow-band THz radiation proposes passing an ultra-relativistic beam through a metallic pipe with small periodic corrugations. We present results of a measurement of such an arrangement at Brookhaven's Accelerator Test Facility (ATF). Our pipe was copper and was 5 cm long; the aperture was cylindrically symmetric, with a 1 mm (radius) bore and a corrugation depth (peak-to-peak) of 60 µm. In the experiment we measured both the effect on the beam of the structure wakefield and the spectral properties of the radiation excited by the beam. We began by injecting a relatively long beam comparedmore » to the wavelength of the radiation, but with short rise time, to excite the structure, and then used a downstream spectrometer to infer the radiation wavelength. This was followed by injecting a shorter bunch, and then using an interferometer (also downstream of the corrugated pipe) to measure the spectrum of the induced THz radiation. For the THz pulse we obtain and compare with calculations: the central frequency, the bandwidth, and the spectral power—compared to a diffraction radiation background signal.« less

  16. Measurements of terahertz radiation generated using a metallic, corrugated pipe

    SciTech Connect

    Bane, Karl; Stupakov, Gennady; Antipov, Sergey; Fedurin, Mikhail; Kusche, Karl; Swinson, Christina; Xiang, Dao

    2016-11-23

    Here, a method for producing narrow-band THz radiation proposes passing an ultra-relativistic beam through a metallic pipe with small periodic corrugations. We present results of a measurement of such an arrangement at Brookhaven's Accelerator Test Facility (ATF). Our pipe was copper and was 5 cm long; the aperture was cylindrically symmetric, with a 1 mm (radius) bore and a corrugation depth (peak-to-peak) of 60 µm. In the experiment we measured both the effect on the beam of the structure wakefield and the spectral properties of the radiation excited by the beam. We began by injecting a relatively long beam compared to the wavelength of the radiation, but with short rise time, to excite the structure, and then used a downstream spectrometer to infer the radiation wavelength. This was followed by injecting a shorter bunch, and then using an interferometer (also downstream of the corrugated pipe) to measure the spectrum of the induced THz radiation. For the THz pulse we obtain and compare with calculations: the central frequency, the bandwidth, and the spectral power—compared to a diffraction radiation background signal.

  17. Transient coexisting nanophases in ultrathin films confined between corrugated walls

    NASA Astrophysics Data System (ADS)

    Curry, Joan E.; Zhang, Fushan; Cushman, John H.; Schoen, Martin; Diestler, Dennis J.

    1994-12-01

    Grand-canonical Monte Carlo and microcanonical molecular dynamics methods have been used to simulate an ultrathin monatomic film confined to a slit-pore [i.e., between solid surfaces (walls)]. Both walls comprise atoms rigidly fixed in the face centered cubic (100) configuration; one wall is smooth on a nanoscale and the other is corrugated (i.e., scored with regularly spaced rectilinear grooves one to several nanometers wide). Properties of the film have been computed as a function of the lateral alignment (registry), with the temperature, chemical potential, and distance between the walls kept constant. Changing the registry carries the film through a succession of equilibrium states, ranging from all solid at one extreme to all fluid at the other. Over a range of intermediate registries the film consists of fluid and solid portions in equilibrium, that is fluid-filled nanocapillaries separated by solid strips. The range of registries over which such fluid-solid equilibria exist depends upon the width of the grooves and the frequency of the corrugation. For grooves of width comparable to the range of the interatomic potential, fluid and solid phases cease to coexist. In the limit of very wide grooves the character of the film is similar to that of the film confined by strictly smooth walls. The rich phase behavior of the confined film due to the coupling between molecular (registry) and nano (corrugation) scales has obvious implications for boundary lubrication.

  18. Measurements of terahertz radiation generated using a metallic, corrugated pipe

    NASA Astrophysics Data System (ADS)

    Bane, Karl; Stupakov, Gennady; Antipov, Sergey; Fedurin, Mikhail; Kusche, Karl; Swinson, Christina; Xiang, Dao

    2017-02-01

    A method for producing narrow-band THz radiation proposes passing an ultra-relativistic beam through a metallic pipe with small periodic corrugations. We present results of a measurement of such an arrangement at Brookhaven's Accelerator Test Facility (ATF). Our pipe was copper and was 5 cm long; the aperture was cylindrically symmetric, with a 1 mm (radius) bore and a corrugation depth (peak-to-peak) of 60 μm. In the experiment we measured both the effect on the beam of the structure wakefield and the spectral properties of the radiation excited by the beam. We began by injecting a relatively long beam compared to the wavelength of the radiation, but with short rise time, to excite the structure, and then used a downstream spectrometer to infer the radiation wavelength. This was followed by injecting a shorter bunch, and then using an interferometer (also downstream of the corrugated pipe) to measure the spectrum of the induced THz radiation. For the THz pulse we obtain and compare with calculations: the central frequency, the bandwidth, and the spectral power-compared to a diffraction radiation background signal.

  19. Noncontact gears. II. Casimir torque between concentric corrugated cylinders for the scalar case

    NASA Astrophysics Data System (ADS)

    Cavero-Peláez, Inés; Milton, Kimball A.; Parashar, Prachi; Shajesh, K. V.

    2008-09-01

    The Casimir interaction between two concentric corrugated cylinders provides the mechanism for noncontact gears. To this end, we calculate the Casimir torque between two such cylinders, described by δ-potentials, which interact through a scalar field. We derive analytic expressions for the Casimir torque for the case when the corrugation amplitudes are small in comparison to the corrugation wavelengths. We derive explicit results for the Dirichlet case, and exact results for the weak coupling limit, in the leading order. The results for the corrugated cylinders approach the corresponding expressions for the case of corrugated parallel plates in the limit of large radii of cylinders (relative to the difference in their radii) while keeping the corrugation wavelength fixed.

  20. Noncontact gears. II. Casimir torque between concentric corrugated cylinders for the scalar case

    SciTech Connect

    Cavero-Pelaez, Ines; Milton, Kimball A.; Parashar, Prachi; Shajesh, K. V.

    2008-09-15

    The Casimir interaction between two concentric corrugated cylinders provides the mechanism for noncontact gears. To this end, we calculate the Casimir torque between two such cylinders, described by {delta}-potentials, which interact through a scalar field. We derive analytic expressions for the Casimir torque for the case when the corrugation amplitudes are small in comparison to the corrugation wavelengths. We derive explicit results for the Dirichlet case, and exact results for the weak coupling limit, in the leading order. The results for the corrugated cylinders approach the corresponding expressions for the case of corrugated parallel plates in the limit of large radii of cylinders (relative to the difference in their radii) while keeping the corrugation wavelength fixed.

  1. Radiation characteristics of a corrugated circular cylindrical waveguide horn excited in the TE11 mode

    NASA Astrophysics Data System (ADS)

    Narasimhan, M. S.; Govind, K. R.

    1988-08-01

    The design and experimental studies on a corrugated circular cyclindrical waveguide antenna that is feed-excited in the TE11 mode with suppressed far-out sidelobes are reported. To reduce the spillover in the region theta = 90 deg - 180 deg, an attempt was made to introduce circumferential corrugations on the outer surface of the waveguide wall. The design criterion used was that a minimum of 11 corrugations per wavelength were used, and in all there were 25 corrugations. The reason for selecting 25 corrugations was to ensure that the conduction currents induced on the outer walls of the guide were attenuated substantially and did not contribute to the far-out sidelobes. Measured E-plane and H-plane radiation patterns of the feeds and the corrugated waveguide are presented.

  2. Novel method to fabricate corrugation for distributed-feedback lasers using a grating photomask

    NASA Astrophysics Data System (ADS)

    Okai, Makoto O.; Harada, Tatsuo

    1991-10-01

    A novel method is developed to fabricate varied line-space corrugations to improve the characteristics of distributed feedback (DFB) semiconductor lasers. Mechanically ruled grating patterns are transferred photolithographically to the surface of a semiconductor substrate by a contact mask aliner using the ultraviolet radiation of a He-Cd laser as a light source. The resultant varied line-space corrugation, like (lambda) /4-shift and corrugation-pitch modulation, improves the characteristics of distributed feedback lasers

  3. Effect of corrugated cover directional transmittance on the thermal performance of a solar collector

    NASA Astrophysics Data System (ADS)

    Smith, T. F.; Chaidar, S.

    1981-05-01

    The benefits of light weight, structural strength, and reduced costs without significant reduction of transmission of solar energy of a corrugated fiberglass composite cover promise wide utilization of this cover in solar collectors to suppress convective and radiative heat losses from the absorber panel. In order to evaluate the thermal performance of a collector with a corrugated cover, the directional transmittance of the cover must be available. A study was undertaken to develop a model for the directional transmittance of a corrugated cover as represented by a sinusoidal periodic function. As an application of this model, hourly and daily thermal efficiencies of a solar collector with a corrugated cover are presented.

  4. Open-ended Coaxial Cavities with Corrugated Inner and Outer Walls

    NASA Astrophysics Data System (ADS)

    Ioannidis, Zisis C.; Avramidis, Konstantinos A.; Tigelis, Ioannis G.

    2015-05-01

    In this work an open-ended coaxial cavity with a corrugated insert and a relatively small number of corrugations on the outer wall is studied. In particular, the Spatial Harmonics Method (SHM) is employed in order to derive the TE modes characteristic equation, which is then solved by truncation for the calculation of the corresponding eigenvalues. Special care is given in the expansion functions used in order to avoid numerical instabilities in the calculation of high-order spatial terms. Various cases of outer wall corrugations are studied numerically in order to identify the effect of the outer corrugations and understand the mode coupling mechanism.

  5. Aerodynamic effects of wing corrugation at gliding flight at low Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Meng, Xue Guang; Sun, Mao

    2013-07-01

    Corrugation gives an insect-wing the advantages of low mass, high stiffness, and low membrane stress. Researchers are interested to know if it is also advantageous aerodynamically. Previous works reported that corrugation enhanced the aerodynamic performance of wings at gliding flight. However, Reynolds numbers considered in these studies were higher than that of gliding insects. The present study showed that in the Reynolds number range of gliding insects, corrugation had negative aerodynamic effects. We studied aerodynamic effects of corrugation at gliding motion using the method of computational fluid dynamics, in the Reynolds number range of Re = 200-2400. Different corrugation patterns were considered. The effect of corrugation on aerodynamic performance was identified by comparing the aerodynamic forces between the corrugated and flat-plate wings, and the underlying flow mechanisms of the corrugation effects were revealed by analyzing the flow fields and surface pressure distributions. The findings are as follows: (1) the effect of corrugation is to decrease the lift, and change the drag only slightly (at 15°-25° angles of attack, lift is decreased by about 16%; at smaller angles of attack, the percentage of lift reduction is even larger because the lift is small). (2) Two mechanisms are responsible for the lift reduction. One is that the pleats at the lower surface of the corrugated wing produce relatively strong vortices, resulting in local low-pressure regions on the lower surface of the wing. The other is that corrugation near the leading edge pushes the leading-edge-separation layer slightly upwards and increases the size of the separation bubble above the upper surface, reducing the "suction pressure," or increasing the pressure, on the upper surface.

  6. Coaxial cavities with corrugated inner conductor for gyrotrons

    SciTech Connect

    Iatrou, C.T.; Kern, S. |; Pavelyev, A.B.

    1996-01-01

    High-frequency, high-power gyrotron oscillators are under development for plasma heating in future fusion reactors. The main technological constrain in the design of a gyrotron cavity is the thermal wall loading, which must be limited to 2--3 kW/cm{sup 2} for long pulses or CW operation. This paper investigates coaxial gyrotron cavities with longitudinal slots on the inner conductor as a means to reduce the number of possible competing modes. In the analytic theory the corrugated surface is treated as a homogeneous impedance surface (impedance corrugation) to obtain simple formulas for the characteristic equation of the eigenmodes, for the electromagnetic fields and the wall losses. The developed model applies if the number of slots is sufficiently high (cutoff wavelength much larger than the corrugation period). The characteristic equation in terms of the ratio C of the outer wall radius to the inner conductor radius is solved numerically to determine a range of eigenvalues and C where the eigenvalue curves are monotonically decreasing. In such a region a cavity having its inner conductor downtapered (radius decreasing toward the cavity output) can be used to reduce the diffractive quality factors of several modes, leaving the working mode undisturbed and without favoring other modes. In addition the electromagnetic field profiles are investigated, and in particular it is shown that for certain cavity parameters a mode could have its energy concentrated close to the inner conductor. As a check on the validity of the theoretical approximations, simulations with the MAFIA code are carried out. These give good agreement with the results of the analytic equations.

  7. High light transmission through thin absorptive corrugated films.

    PubMed

    Dmitruk, Nicolas L; Korovin, Alexander V

    2008-05-01

    The enhancement of light transmittance through periodically relief thin absorptive film at surface plasmon polariton excitation conditions, as a function of relief interrelation, was considered theoretically. Our calculation of transmittance-reflectance through periodically relief thin absorptive film was performed in the framework of differential formalism. There are two basic relief interrelation forms, namely, correlated and anticorrelated ones. The obtained spectral and angular dependencies demonstrate an essential increase of surface plasmon polariton peaks in the case of anticorrelated corrugation of film in comparison with the correlated ones.

  8. Corrugation of the skull in Paget's disease of bone.

    PubMed Central

    Chakravorty, N. K.; Das, S. K.; Kataria, M. S.

    1977-01-01

    Paget's disease of bone has been known for about 100 years and the usual deformities of bone, e.g. bowed tibia, large head, are well described in medical text books. However, there does not appear to have been a description of corrugation of the skull as a recognized deformity in Paget's disease. Three cases are now described to illustrate this deformity as an unusual but valuable sign in this disease. Images Fig. 5 Fig. 6 Fig. 1 Fig. 2 Fig. 3 Fig. 4 Figs. 7 and 8 PMID:876912

  9. Aerodynamic effects of corrugation in flapping insect wings in hovering flight.

    PubMed

    Meng, Xue Guang; Xu, Lei; Sun, Mao

    2011-02-01

    We have examined the aerodynamic effects of corrugation in model insect wings that closely mimic the wing movements of hovering insects. Computational fluid dynamics were used with Reynolds numbers ranging from 35 to 3400, stroke amplitudes from 70 to 180 deg and mid-stroke angles of incidence from 15 to 60 deg. Various corrugated wing models were tested (care was taken to ensure that the corrugation introduced zero camber). The main results are as follows. At typical mid-stroke angles of incidence of hovering insects (35-50 deg), the time courses of the lift, drag, pitching moment and aerodynamic power coefficients of the corrugated wings are very close to those of the flat-plate wing, and compared with the flat-plate wing, the corrugation changes (decreases) the mean lift by less than 5% and has almost no effect on the mean drag, the location of the center of pressure and the aerodynamic power required. A possible reason for the small aerodynamic effects of wing corrugation is that the wing operates at a large angle of incidence and the flow is separated: the large angle of incidence dominates the corrugation in determining the flow around the wing, and for separated flow, the flow is much less sensitive to wing shape variation. The present results show that for hovering insects, using a flat-plate wing to model the corrugated wing is a good approximation.

  10. Adhesive in the buckling failure of corrugated fiberboard : a finite element investigation

    Treesearch

    Adeeb A. Rahman; Said M. Abubakr

    1998-01-01

    This research study proposed to include the glue material in a finite element model that represents the actual geometry and material properties of a corrugated fiberboard. The model is a detailed representation of the different components of the structure (adhesive, linerboard, medium) to perform buckling analysis of corrugated structures under compressive loads. The...

  11. Manipulation of Thought Content as a Determinant of Mood and Corrugator Electromyographic Activity in Depressed Patients

    ERIC Educational Resources Information Center

    Teasdale, John D.; Bancroft, Judy

    1977-01-01

    Examines the effects of unhappy thoughts on mood and corrugator EMG (electromyographic activity) in depressed patients. Its purpose was to obtain evidence relevant to cognitive models of depression and to examine the usefulness of corrugator EMG as an indicator of depressed mood. (Author/RK)

  12. Surface-plasmon cross coupling in molecular fluorescence near a corrugated thin metal film

    NASA Technical Reports Server (NTRS)

    Gruhlke, R. W.; Holland, W. R.; Hall, D. G.

    1968-01-01

    Surface plasmons on opposite sides of a thin metal film can cross couple in the presence of a surface corrugation, or grating. The observation of this cross-coupling phenomenon as a radiative-decay mechanism for molecules near a corrugated thin metal film is reported.

  13. Effect of long-range structural corrugations on magnetotransport properties of phosphorene in tilted magnetic field

    NASA Astrophysics Data System (ADS)

    Mogulkoc, A.; Modarresi, M.; Rudenko, A. N.

    2017-08-01

    Rippling is an inherent quality of two-dimensional materials playing an important role in determining their properties. Here, we study the effect of structural corrugations on the electronic and transport properties of monolayer black phosphorus (phosphorene) in the presence of tilted magnetic field. We follow a perturbative approach to obtain analytical corrections to the spectrum of Landau levels induced by a long-wavelength corrugation potential. We show that surface corrugations have a non-negligible effect on the electronic spectrum of phosphorene in tilted magnetic field. Particularly, the Landau levels are shown to exhibit deviations from the linear field dependence. The observed effect become especially pronounced at large tilt angles and corrugation amplitudes. Magnetotransport properties are further examined in the low temperature regime taking into account impurity scattering. We calculate magnetic field dependence of the longitudinal and Hall resistivities and find that the nonlinear effects reflecting the corrugation might be observed even in moderate fields (B <10 T).

  14. Corrugated Textile based Triboelectric Generator for Wearable Energy Harvesting.

    PubMed

    Choi, A Young; Lee, Chang Jun; Park, Jiwon; Kim, Dogyun; Kim, Youn Tae

    2017-03-28

    Triboelectric energy harvesting has been applied to various fields, from large-scale power generation to small electronics. Triboelectric energy is generated when certain materials come into frictional contact, e.g., static electricity from rubbing a shoe on a carpet. In particular, textile-based triboelectric energy-harvesting technologies are one of the most promising approaches because they are not only flexible, light, and comfortable but also wearable. Most previous textile-based triboelectric generators (TEGs) generate energy by vertically pressing and rubbing something. However, we propose a corrugated textile-based triboelectric generator (CT-TEG) that can generate energy by stretching. Moreover, the CT-TEG is sewn into a corrugated structure that contains an effective air gap without additional spacers. The resulting CT-TEG can generate considerable energy from various deformations, not only by pressing and rubbing but also by stretching. The maximum output performances of the CT-TEG can reach up to 28.13 V and 2.71 μA with stretching and releasing motions. Additionally, we demonstrate the generation of sufficient energy from various activities of a human body to power about 54 LEDs. These results demonstrate the potential application of CT-TEGs for self-powered systems.

  15. Corrugated Waveguide Mode Content Analysis Using Irradiance Moments

    PubMed Central

    Jawla, Sudheer K.; Shapiro, Michael A.; Idei, Hiroshi; Temkin, Richard J.

    2015-01-01

    We present a novel, relatively simple method for determining the mode content of the linearly polarized modes of a corrugated waveguide using the moments of the intensity pattern of the field radiated from the end of the waveguide. This irradiance moment method is based on calculating the low-order irradiance moments, using measured intensity profiles only, of the radiated field from the waveguide aperture. Unlike the phase retrieval method, this method does not use or determine the phase distribution at the waveguide aperture. The new method was benchmarked numerically by comparison with sample mode mixtures. The results predict less than ±0.7% error bar in the retrieval of the mode content. The method was also tested using high-resolution experimental data from beams radiated from 63.5 mm and 19 mm corrugated waveguides at 170 and 250 GHz, respectively. The results showed a very good agreement of the mode content retrieved using the irradiance moment method versus the phase retrieval technique. The irradiance moment method is most suitable for cases where the modal power is primarily in the fundamental HE11 mode, with <8% of the power in high-order modes. PMID:25821260

  16. Corrugated Textile based Triboelectric Generator for Wearable Energy Harvesting

    PubMed Central

    Choi, A Young; Lee, Chang Jun; Park, Jiwon; Kim, Dogyun; Kim, Youn Tae

    2017-01-01

    Triboelectric energy harvesting has been applied to various fields, from large-scale power generation to small electronics. Triboelectric energy is generated when certain materials come into frictional contact, e.g., static electricity from rubbing a shoe on a carpet. In particular, textile-based triboelectric energy-harvesting technologies are one of the most promising approaches because they are not only flexible, light, and comfortable but also wearable. Most previous textile-based triboelectric generators (TEGs) generate energy by vertically pressing and rubbing something. However, we propose a corrugated textile-based triboelectric generator (CT-TEG) that can generate energy by stretching. Moreover, the CT-TEG is sewn into a corrugated structure that contains an effective air gap without additional spacers. The resulting CT-TEG can generate considerable energy from various deformations, not only by pressing and rubbing but also by stretching. The maximum output performances of the CT-TEG can reach up to 28.13 V and 2.71 μA with stretching and releasing motions. Additionally, we demonstrate the generation of sufficient energy from various activities of a human body to power about 54 LEDs. These results demonstrate the potential application of CT-TEGs for self-powered systems. PMID:28349928

  17. The biofouling potential of flow on corrugated surfaces

    NASA Astrophysics Data System (ADS)

    Miño, Gastón L.; Rusconi, Roberto; Kantsler, Vasily; Stocker, Roman

    2015-11-01

    Both natural and man-made surfaces are rarely smooth, and are instead often characterized by geometric heterogeneity or roughness over a broad range of scales. Because of the predicted importance of the local interaction between microorganisms and surfaces, roughness at the microbial scale can be an important element in determining the outcome of microbe-surface interactions, which represent the first step in biofilm formation and biofouling. In microbial habitats this interaction often occurs in flowing fluids, which can be important because regions with high hydrodynamic shear can induce a strong reorientation of bacteria towards surfaces, promoting attachment. Here we study the combination of flow and surface topography using video microscopy of Escherichia coli in corrugated microfluidic channels. We report that flow preferentially promotes attachment to specific regions of a corrugated surface, as result of the hydrodynamics of bacteria swimming in flow. We compute from the data a ``Local Biofouling Potential'' (LBP) and compare this successfully with predictions of a mathematical model, yielding one step towards the ability to mechanistically predict and thus ultimately either prevent or induce biofouling.

  18. Electrodynamics of spoof plasmons in periodically corrugated waveguides.

    PubMed

    Erementchouk, Mikhail; Joy, Soumitra Roy; Mazumder, Pinaki

    2016-11-01

    States of the electromagnetic field confined near a periodically corrugated surface of a perfect conductor, spoof surface plasmon polaritons (SSPP), are approached systematically based on the developed adaptation of the mode matching technique to the transfer matrix formalism. Within this approach, in the approximation of narrow grooves, systems with arbitrary transversal structure can be investigated straightforwardly, thus lifting the restrictions of the effective medium description and usual implementations of mode matching. A compact expression for the SSPP coupling parameter accounting for the effect of higher Bloch modes is found. The results of the general analysis are applied for studying the effect of dielectric environment on SSPP spectra. It is shown that the effective SSPP plasma frequency is unaffected by the dielectric constant of the medium outside of the grooves and the main effect of sufficiently wide dielectric slabs covering the corrugated surface is described by simple rescaling of the maximal value of the Bloch wavenumber and the coupling parameter. Additionally, in the case of a thin dielectric layer, it is shown that SSPP are sensitive to variation of the thickness of the layer on the sub-wavelength scale.

  19. Aeroacoustics of the swinging corrugated tube: voice of the Dragon.

    PubMed

    Nakiboğlu, Güneş; Rudenko, Oleksii; Hirschberg, Avraham

    2012-01-01

    When one swings a short corrugated pipe segment around one's head, it produces a musically interesting whistling sound. As a musical toy it is called a "Hummer" and as a musical instrument, the "Voice of the Dragon." The fluid dynamics aspects of the instrument are addressed, corresponding to the sound generation mechanism. Velocity profile measurements reveal that the turbulent velocity profile developed in a corrugated pipe differs notably from the one of a smooth pipe. This velocity profile appears to have a crucial effect both on the non-dimensional whistling frequency (Strouhal number) and on the amplitude of the pressure fluctuations. Using a numerical model based on incompressible flow simulations and vortex sound theory, excellent predictions of the whistling Strouhal numbers are achieved. The model does not provide an accurate prediction of the amplitude. In the second part of the paper the sound radiation from a Hummer is discussed. The acoustic measurements obtained in a semi-anechoic chamber are compared with a theoretical radiation model. Globally the instrument behaves as a rotating (Leslie) horn. The effects of Doppler shift, wall reflections, bending of the tube, non-constant rotational speed on the observed frequency, and amplitude are discussed. © 2012 Acoustical Society of America.

  20. Theory of a ubitron in a corrugated waveguide

    SciTech Connect

    Freund, H.P.; Nguyen, K.; Pershing, D.E.

    1996-12-31

    A K{sub a} band ubitron amplifier is currently under development at NRL utilizing grazing intersection for wide instantaneous bandwidth, circularly polarized wiggler and microwave fields for high gain and power, and a high quality Pierce gun generating a cylindrical, uniform density electron beam for high efficiency. The dispersion characteristics of a periodic waveguide can be exploited for low voltage ubitron operation. Operation in the HE{sub 11} mode of a corrugated cylindrical waveguide permits broader bandwidth amplification at lower voltages than is possible with a smooth waveguide. While the wave is slower than the smooth waveguide dispersion characteristic, the amplifier still operates on the fundamental space harmonic as a fast-wave device. An extensive investigation of several waveguide/wiggler geometries has been completed. Preliminary calculations using a dielectrically loaded corrugated waveguide indicate that 20% bandwidth operation in K{sub a} band is possible at voltages {approximately} 150 kV with a 8--9 mm period wiggler generating a 930 G transverse magnetic field. Design details and performance calculations using the 3-D nonlinear code TARANTULA will be presented.

  1. Imaging Local Electronic Corrugations and Doped Regions in Graphene

    SciTech Connect

    B Schultz; C Patridge; V Lee; C Jaye; P Lysaght; C Smith; J Barnett; D Fischer; D Prendergast; S Banerjee

    2011-12-31

    Electronic structure heterogeneities are ubiquitous in two-dimensional graphene and profoundly impact the transport properties of this material. Here we show the mapping of discrete electronic domains within a single graphene sheet using scanning transmission X-ray microscopy in conjunction with ab initio density functional theory calculations. Scanning transmission X-ray microscopy imaging provides a wealth of detail regarding the extent to which the unoccupied levels of graphene are modified by corrugation, doping and adventitious impurities, as a result of synthesis and processing. Local electronic corrugations, visualized as distortions of the {pi}*cloud, have been imaged alongside inhomogeneously doped regions characterized by distinctive spectral signatures of altered unoccupied density of states. The combination of density functional theory calculations, scanning transmission X-ray microscopy imaging, and in situ near-edge X-ray absorption fine structure spectroscopy experiments also provide resolution of a longstanding debate in the literature regarding the spectral assignments of pre-edge and interlayer states.

  2. A comprehensive track model for the improvement of corrugation models

    NASA Astrophysics Data System (ADS)

    Gómez, J.; Vadillo, E. G.; Santamaría, J.

    2006-06-01

    This paper presents a detailed model of the railway track based on wave propagation, suitable for corrugation studies. The model analyses both the vertical and the transverse dynamics of the track. Using the finite strip method (FSM), only the cross-section of the rail must be meshed, and thus it is not necessary to discretise a whole span in 3D. This model takes into account the discrete nature of the support, introducing concepts pertaining to the theory of periodic structures in the formulation. Wave superposition is enriched taking into account the contribution of residual vectors. In this way, the model obtains accurate results when a finite section of railway track is considered. Results for the infinite track have been compared against those presented by Gry and Müller. Aside from the improvements provided by the model presented in this paper, which Gry's and Müller's models do not contemplate, the results arising from the comparison prove satisfactory. Finally, the calculated receptances are compared against the experimental values obtained by the authors, demonstrating a fair degree of adequacy. Finally, these receptances are used within a linear model of corrugation developed by the authors.

  3. Corrugated Textile based Triboelectric Generator for Wearable Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Choi, A. Young; Lee, Chang Jun; Park, Jiwon; Kim, Dogyun; Kim, Youn Tae

    2017-03-01

    Triboelectric energy harvesting has been applied to various fields, from large-scale power generation to small electronics. Triboelectric energy is generated when certain materials come into frictional contact, e.g., static electricity from rubbing a shoe on a carpet. In particular, textile-based triboelectric energy-harvesting technologies are one of the most promising approaches because they are not only flexible, light, and comfortable but also wearable. Most previous textile-based triboelectric generators (TEGs) generate energy by vertically pressing and rubbing something. However, we propose a corrugated textile-based triboelectric generator (CT-TEG) that can generate energy by stretching. Moreover, the CT-TEG is sewn into a corrugated structure that contains an effective air gap without additional spacers. The resulting CT-TEG can generate considerable energy from various deformations, not only by pressing and rubbing but also by stretching. The maximum output performances of the CT-TEG can reach up to 28.13 V and 2.71 μA with stretching and releasing motions. Additionally, we demonstrate the generation of sufficient energy from various activities of a human body to power about 54 LEDs. These results demonstrate the potential application of CT-TEGs for self-powered systems.

  4. Electrodynamics of spoof plasmons in periodically corrugated waveguides

    NASA Astrophysics Data System (ADS)

    Erementchouk, Mikhail; Joy, Soumitra Roy; Mazumder, Pinaki

    2016-11-01

    States of the electromagnetic field confined near a periodically corrugated surface of a perfect conductor, spoof surface plasmon polaritons (SSPP), are approached systematically based on the developed adaptation of the mode matching technique to the transfer matrix formalism. Within this approach, in the approximation of narrow grooves, systems with arbitrary transversal structure can be investigated straightforwardly, thus lifting the restrictions of the effective medium description and usual implementations of mode matching. A compact expression for the SSPP coupling parameter accounting for the effect of higher Bloch modes is found. The results of the general analysis are applied for studying the effect of dielectric environment on SSPP spectra. It is shown that the effective SSPP plasma frequency is unaffected by the dielectric constant of the medium outside of the grooves and the main effect of sufficiently wide dielectric slabs covering the corrugated surface is described by simple rescaling of the maximal value of the Bloch wavenumber and the coupling parameter. Additionally, in the case of a thin dielectric layer, it is shown that SSPP are sensitive to variation of the thickness of the layer on the sub-wavelength scale.

  5. Simulation of terahertz generation in corrugated plasma waveguides.

    PubMed

    Pearson, Andrew J; Palastro, John; Antonsen, Thomas M

    2011-05-01

    We simulate the response of a corrugated plasma channel to an ultrashort laser pulse in two dimensions with the goal of demonstrating the production of terahertz frequency electromagnetic modes. Corrugated channels support electromagnetic modes that have a Floquet-type dispersion relation and thus consist of a sum of spatial harmonics with subluminal phase velocities. This allows the possibility of phase matching between the ponderomotive potential associated with the laser pulse and the electromagnetic modes of the channel. Since the bandwidth of an ultrashort pulse includes terahertz frequencies, significant excitation of terahertz radiation is possible. Here we consider realistic density profiles to obtain predictions of the terahertz power output and mode structure for a channel with periodic boundary conditions. We then estimate pulse depletion effects from our simulation results. The fraction of laser energy converted to terahertz is independent of laser pulse energy in the linear regime, and we find it to be around 1%. Extrapolating to a pulse energy of 0.5 J gives a terahertz power output of 6 mJ with a pulse depletion length of less than 20 cm.

  6. Investigation into the vibration of metro bogies induced by rail corrugation

    NASA Astrophysics Data System (ADS)

    Ling, Liang; Li, Wei; Foo, Elbert; Wu, Lei; Wen, Zefeng; Jin, Xuesong

    2017-01-01

    The current research of rail corrugation mainly focuses on the mechanisms of its formation and development. Compared with the root causes and development mechanisms, the wheel-rail impacts, the fatigue failure of vehicle-track parts, and the loss of ride comfort due to rail corrugation should also be taken into account. However, the influences of rail corrugation on vehicle and track vibration, and failure of vehicle and track structural parts are barely discussed in the literature. This paper presents an experimental and numerical investigation of the structural vibration of metro bogies caused by rail corrugation. Extensive experiments are conducted to investigate the effects of short-pitch rail corrugation on the vibration accelerations of metro bogies. A dynamic model of a metro vehicle coupled with a concrete track is established to study the influence of rail corrugation on the structural vibration of metro bogies. The field test results indicate that the short-pitch rail corrugation generates strong vibrations on the axle-boxes and the bogie frames, therefore, accelerates the fatigue failure of the bogie components. The numerical results show that short-pitch rail corrugation may largely reduce the fatigue life of the coil spring, and improving the damping value of the primary vertical dampers is likely to reduce the strong vibration induced by short-pitch rail corrugation. This research systematically studies the effect of rail corrugation on the vibration of metro bogies and proposes some remedies for mitigating strong vibrations of metro bogies and reducing the incidence of failure in primary coil springs, which would be helpful in developing new metro bogies and track maintenance procedures.

  7. Study on rail corrugation of a metro tangential track with Cologne-egg type fasteners

    NASA Astrophysics Data System (ADS)

    Cui, X. L.; Chen, G. X.; Yang, H. G.; Zhang, Q.; Ouyang, H.; Zhu, M. H.

    2016-03-01

    In Chinese metro lines, rail corrugation on both tangential and tight curved tracks with Cologne-egg type fasteners is very severe. Based on the viewpoint of friction-induced vibration causing rail corrugation, the rail corrugation on a tangential track with Cologne-egg type fasteners is studied in this paper. A vibration model of an elastic multiple-wheelset-track system with Cologne-egg type fasteners is established. Both the complex eigenvalue analysis and the transient dynamic analysis are performed to study the stability and the dynamic performance of the wheelset-track system. The simulation results show that a low rail support stiffness value is responsible for rail corrugation on the tangential track. When the Cologne-egg fasteners characterised by a lower stiffness value are replaced with the DTVI2 fasteners characterised by a higher stiffness value, rail corrugation disappears. However, rail corrugation on tight curved tracks cannot be suppressed using the same replacement. The above conclusions are consistent with the corrugation occurrences in actual metro tracks.

  8. Comparison of manufacturing of lightweight corrugated sheet sandwiches by hydroforming and incremental sheet forming

    NASA Astrophysics Data System (ADS)

    Maqbool, Fawad; Elze, Lars; Seidlitz, Holger; Bambach, Markus

    2016-10-01

    Sandwich materials made from corrugated sheet metal provide excellent mechanical properties for lightweight design without using filler material. The increased mechanical properties of these sandwich materials are achieved by the 3-D geometry of the corrugated sheet and the hardening due to pre-forming. In the present study, manufacturing of corrugated sheet metal consisting of hexagonal bulge patterns through hydroforming and incremental forming is analyzed. Double layered corrugated sheet metal sandwiches with hexagonal patterns of free-form bulge geometries are investigated through finite element analysis for the maximum increase in stiffness over the normal flat sheets. The analysis shows that a bending stiffness increase of up to 13 times over flat sheet of the same mass is attainable by corrugated sandwiches. Further, it is proved for these types of corrugation sandwiches that stiffness increases by increasing the height of the corrugation bulge but that hydroforming poses restrictions with respect to bulge height, since it is limited by forming force and formability of the material. Incremental sheet metal forming can be used to produce sheets with a hexagonal bulge pattern with increased height. Hence, a higher increase in stiffness as compared to hydroforming is possible but at the expense of process speed.

  9. Numerical investigation of the aerodynamic and structural characteristics of a corrugated wing

    NASA Astrophysics Data System (ADS)

    Hord, Kyle

    Previous experimental studies on static, bio-inspired corrugated wings have shown that they produce favorable aerodynamic properties such as delayed stall compared to streamlined wings and flat plates at high Reynolds numbers (Re ≥ 4x104). The majority of studies have been carried out with scaled models of dragonfly forewings from the Aeshna Cyanea in either wind tunnels or water channels. In this thesis, the aerodynamics of a corrugated airfoil was studied using computational fluid dynamics methods at a low Reynolds number of 1000. Structural analysis was also performed using the commercial software SolidWorks 2009. The flow field is described by solving the incompressible Navier-Stokes equations on an overlapping grid using the pressure-Poisson method. The equations are discretized in space with second-order accurate central differences. Time integration is achieved through the second-order Crank-Nicolson implicit method. The complex vortex structures that form in the corrugated airfoil valleys and around the corrugated airfoil are studied in detail. Comparisons are made with experimental measurements from corrugated wings and also with simulations of a flat plate. Contrary to the studies at high Reynolds numbers, our study shows that at low Reynolds numbers the wing corrugation does not provide any aerodynamic benefit compared to a smoothed flat plate. Instead, the corrugated profile generates more pressure drag which is only partially offset by the reduction of friction drag, leading to more total drag than the flat plate. Structural analysis shows that the wing corrugation can increase the resistance to bending moments on the wing structure. A smoothed structure has to be three times thicker to provide the same stiffness. It was concluded the corrugated wing has the structural benefit to provide the same resistance to bending moments with a much reduced weight.

  10. Modeling noncontact atomic force microscopy resolution on corrugated surfaces.

    PubMed

    Burson, Kristen M; Yamamoto, Mahito; Cullen, William G

    2012-01-01

    Key developments in NC-AFM have generally involved atomically flat crystalline surfaces. However, many surfaces of technological interest are not atomically flat. We discuss the experimental difficulties in obtaining high-resolution images of rough surfaces, with amorphous SiO(2) as a specific case. We develop a quasi-1-D minimal model for noncontact atomic force microscopy, based on van der Waals interactions between a spherical tip and the surface, explicitly accounting for the corrugated substrate (modeled as a sinusoid). The model results show an attenuation of the topographic contours by ~30% for tip distances within 5 Å of the surface. Results also indicate a deviation from the Hamaker force law for a sphere interacting with a flat surface.

  11. Terahertz Radiation from a Pipe with Small Corrugations

    SciTech Connect

    Bane, K.L.F.; Stupakov, G.; /SLAC

    2012-01-26

    We have studied through analytical and numerical methods the use of a relativistic electron bunch to drive a metallic beam pipe with small corrugations for the purpose of generating terahertz radiation. For the case of a pipe with dimensions that do not change along its length, we have shown that - with reasonable parameters - one can generate a narrow-band radiation pulse with frequency {approx}1 THz, and total energy of a few milli-Joules. The pulse length tends to be on the order of tens of picoseconds. We have also shown that, if the pipe radius is tapered along its length, the generated pulse will end up with a frequency chirp; if the pulse is then made to pass through a compressor, its final length can be reduced to a few picoseconds and its peak power increased to 1 GW. We have also shown that wall losses tend to be significant and need to be included in the structure design.

  12. Calculation of eigenmodes in a nonperiodic corrugated waveguide

    SciTech Connect

    Tigelis, I.G.; Pedrozzi, M.; Cottis, P.G.; Vomvoridis, J.L.

    1997-02-01

    A theoretical technique for determining the dispersion relation, the electromagnetic field components, and the quality factor of a dielectric-loaded nonperiodic corrugated waveguide is presented for the case of azimuthally symmetric TM waves. The Floquet theorem is used to express the field distribution in the vacuum region, while an eigenfunction expansion is employed in each dielectric region, with the appropriate boundary conditions applied at the interfaces, leading to an infinite system of equations. This system is solved numerically by truncation, while the convergence of the solution is examined with the number of spatial harmonics. Based on this formulation, a numerical code, called FISHBONE-TM, is developed and its results are compared with those obtained with an established code (CASCADE) based on the scattering-matrix method.

  13. A nonlinear investigation of corrugation instabilities in magnetic accretion shocks

    NASA Astrophysics Data System (ADS)

    Ernst, Scott

    2011-05-01

    Accretion shock waves are present in many important astrophysical systems and have been a focus of research for decades. These investigations provide a large body of understanding as to the nature, characteristics, and evolutionary behaviors of accretion shock waves over a wide range of conditions. However, largely absent are investigations into the properties of accretion shock waves in the presence of strong magnetic fields. In such cases these strong magnetic fields can significantly alter the stability behaviors and evolution of the accretion shock wave through the production and propagation of magnetic waves as well as magnetically constrained advection. With strong magnetic fields likely found in a number of accretion shock systems, such as compact binary and protostellar systems, a better understanding of the behaviors of magnetic accretion shock waves is needed. A new magnetohydrodynamics simulation tool, IMOGEN, was developed to carry out an investigation of instabilities in strong, slow magnetic accretion shocks by modelling their long-term, nonlinear evolution. IMOGEN implements a relaxed, second-order, total variation diminishing, monotonic upwind scheme for conservation laws and incorporates a staggered-grid constrained transport scheme for magnetic advection. Through the simulated evolution of magnetic accretion shocks over a wide range of initial conditions, it has been shown, for sufficiently high magnetic field strengths, that magnetic accretion shocks are generally susceptible to corrugation instabilities, which arise in the presence of perturbations of the initial shock front. As these corrugation instabilities grow, they manifestas magnetic wave propagation in the upstream region of the accretion column, which propagate away from the accretion shock front, and as density columns, or fingers, that grow into the higher density downstream flow, defined and constrained by current loops created during the early evolution of the instability.

  14. Geometrical properties of turbulent premixed flames and other corrugated interfaces.

    PubMed

    Thiesset, F; Maurice, G; Halter, F; Mazellier, N; Chauveau, C; Gökalp, I

    2016-01-01

    This study focuses on the geometrical properties of turbulent flame fronts and other interfaces. Toward that end, we use an original tool based on proper orthogonal decomposition (POD), which is applied to the interface spatial coordinates. The focus is mainly on the degree of roughness of the flame front, which is quantified through the scale dependence of its coverage arclength. POD is first validated by comparing with the caliper technique. Fractal characteristics are extracted in an unambiguous fashion using a parametric expression which appears to be impressively well suited for representing Richardson plots. Then it is shown that, for the range of Reynolds numbers investigated here, the scale-by-scale contribution to the arclength does not comply with scale similarity, irrespectively of the type of similarity which is invoked. The finite ratios between large and small scales, referred to as finite Reynolds number effects, are likely to explain this observation. In this context, the Reynolds number that ought to be achieved for a proper inertial range to be discernible, and for scale similarity to be likely to apply, is calculated. Fractal characteristics of flame folding are compared to available predictions. It is confirmed that the inner cutoff satisfactorily correlates with the Kolmogorov scale while the outer cutoff appears to be proportional to the integral length scale. However, the scaling for the fractal dimension is much less obvious. It is argued that much higher Reynolds numbers have to be reached for drawing firm statements about the evolution (or constancy) of the fractal dimension with respect to flame and flow parameters. Finally, a heuristic phenomenology of corrugated interfaces is highlighted. The degree of generality of the latter phenomenology is confirmed by comparing the folding of different interfaces including a turbulent-nonturbulent interface, a liquid jet destabilized by a surrounding air jet, a cavitating flow, and an isoscalar

  15. Gyrokinetic simulations of off-axis minimum-q profile corrugations

    SciTech Connect

    Waltz, R.E.; Austin, M.E.; Burrell, K.H.; Candy, J.

    2006-05-15

    Quasiequilibrium radial 'profile corrugations' in the electron temperature gradient are found at lowest-order singular surfaces in global gyrokinetic code simulations of both monotonic-q and off-axis minimum-q discharges. The profile corrugations in the temperature and density gradients are time-averaged components of zonal flows. The m/n=2/1 electron temperature gradient corrugation is measurably large and appears to trigger an internal transport barrier as the off-axis minimum-q=2 surfaces enter the plasma.

  16. The electronic and magnetic properties of corrugated zigzag graphene nanoribbons with divacancy defects

    NASA Astrophysics Data System (ADS)

    Tan, Xiao-Dong; Liao, Xiao-Ping; Sun, Litao

    2017-01-01

    We investigate the electronic and magnetic properties of the corrugated zigzag graphene nanoribbons (ZGNRs) with divacancy defects by means of the first principle calculations. We show that the magnitude of corrugation in the defective ZGNR determines whether the system is in the antiferromagnetic state, in the ferromagnetic state, or in the nonmagnetic state. Correspondingly, the mutual transition between the semiconductor and the metal can also be realized in this structure. Moreover, for semiconductors the energy gap displays oscillating behaviors as the magnitude of corrugation increases. These results are identified as being useful in manufacturing flexible devices.

  17. Bending of five-layer beams with lengthwise corrugated main core

    SciTech Connect

    Magnucka-Blandzi, Ewa; Walczak, Zbigniew

    2015-03-10

    The paper is devoted to one orthotropic thin-walled sandwich beam with trapezoidal core and two-layer facings. The inner layers of the facings are also corrugated. The orientation of the corrugations of the inner layers of the facings is perpendicular to trapezoidal corrugation of the beam core. The mathematical and physical model of this beam is formulated, and also the field of displacements. Basing on the principle of the total potential energy the system of equilibrium equations is derived. The analytical solutions will be verified numerically with the use of the finite element method (MES)

  18. Experimental and analytical determination of vibration characteristics of corrugated, flexibly supported, heat-shield panels

    NASA Technical Reports Server (NTRS)

    Carden, H. D.

    1974-01-01

    Experimental and analytical natural frequencies, nodal patterns, and typical modal displacements for a corrugated, flexibly supported, heat-shield panel are discussed. Good correlation was found between the experimental data and NASTRAN analytical results for the corrugated panel over a relatively wide frequency spectrum covered in the investigation. Of the two experimental techniques used for mode shape and displacement measurements (a noncontacting displacement sensor system and a holographic technique using a helium-neon, continuous-wave laser), the holographic technique was found, in the present investigation, to be faster and better suited for determining a large number of complex nodal patterns of the corrugated panel.

  19. Plastic Jellyfish.

    ERIC Educational Resources Information Center

    Moseley, Christine

    2000-01-01

    Presents an environmental science activity designed to enhance students' awareness of the hazards of plastic waste for wildlife in aquatic environments. Discusses how students can take steps to reduce the effects of plastic waste. (WRM)

  20. Plastic Jellyfish.

    ERIC Educational Resources Information Center

    Moseley, Christine

    2000-01-01

    Presents an environmental science activity designed to enhance students' awareness of the hazards of plastic waste for wildlife in aquatic environments. Discusses how students can take steps to reduce the effects of plastic waste. (WRM)

  1. Surface Impedance Formalism for a Metallic Beam Pipe with Small Corrugations

    SciTech Connect

    Stupakov, G.; Bane, K.L.F.; /SLAC

    2012-08-30

    A metallic pipe with wall corrugations is of special interest in light of recent proposals to use such a pipe for the generation of terahertz radiation and for energy dechirping of electron bunches in free electron lasers. In this paper we calculate the surface impedance of a corrugated metal wall and show that it can be reduced to that of a thin layer with dielectric constant {epsilon} and magnetic permeability {mu}. We develop a technique for the calculation of these constants, given the geometrical parameters of the corrugations. We then calculate, for the specific case of a round metallic pipe with small corrugations, the frequency and strength of the resonant mode excited by a relativistic beam. Our analytical results are compared with numerical simulations, and are shown to agree well.

  2. 5. Detail, 5panel door and corrugated metal siding, Oil House, ...

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

    5. Detail, 5-panel door and corrugated metal siding, Oil House, Southern Pacific Railroad Carlin Shops, southwest facade, view to northeast (210mm lens). - Southern Pacific Railroad, Carlin Shops, Oil House, Foot of Sixth Street, Carlin, Elko County, NV

  3. Flexural strengthening of Reinforced Concrete (RC) Beams Retrofitted with Corrugated Glass Fiber Reinforced Polymer (GFRP) Laminates

    NASA Astrophysics Data System (ADS)

    Aravind, N.; Samanta, Amiya K.; Roy, Dilip Kr. Singha; Thanikal, Joseph V.

    2015-01-01

    Strengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. Many researchers used plain Glass Fiber Reinforced Polymer (GFRP) sheets for strengthening Reinforced Concrete (RC) beams. In this research work, rectangular corrugated GFRP laminates were used for strengthening RC beams to achieve higher flexural strength and load carrying capacity. Type and dimensions of corrugated profile were selected based on preliminary study using ANSYS software. A total of twenty one beams were tested to study the load carrying capacity of control specimens and beams strengthened with plain sheets and corrugated laminates using epoxy resin. This paper presents the experimental and theoretical study on flexural strengthening of Reinforced Concrete (RC) beams using corrugated GFRP laminates and the results are compared. Mathematical models were developed based on the experimental data and then the models were validated.

  4. 14. DETAIL OF SOUTHWEST FRONT OF WAREHOUSE, SHOWING CORRUGATED PLASTER/ASBESTOS ...

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

    14. DETAIL OF SOUTHWEST FRONT OF WAREHOUSE, SHOWING CORRUGATED PLASTER/ASBESTOS WALLS, WINDOWS AND ROOF. VIEW TO NORTHEAST. - Commercial & Industrial Buildings, International Harvester Company Showroom, Office & Warehouse, 10 South Main Street, Dubuque, Dubuque County, IA

  5. Heat transfer and fluid flow characteristics of spanwise-periodic corrugated ducts

    NASA Astrophysics Data System (ADS)

    Sparrow, E. M.; Charmchi, M.

    1980-04-01

    An analytical study is made of the laminar flow and heat transfer in ducts whose cross section is bounded by a wall with periodic corrugations distributed across the span; the other bounding wall is parallel to the corrugated wall and is plane. The study consists of two parts, the first of which is aimed at providing basic heat transfer and fluid flow results while the second utilizes and illuminates these results by means of performance evaluation and comparisons. The basic results, determined numerically, encompass Nusselt numbers, friction factors, isovels and isotherms, and cross sectional mass flow distributions. For the performance evaluations, comparisons were made between the corrugated-wall duct and the parallel plate channel. It was demonstrated that if the temperature of the duct wall is to be minimized, as in an air-operated solar collector, a corrugated duct can be highly effective, but at the price of additional surface area and greater duct height.

  6. Leaky-Wave Radiations by Modulating Surface Impedance on Subwavelength Corrugated Metal Structures

    PubMed Central

    Cai, Ben Geng; Li, Yun Bo; Ma, Hui Feng; Jiang, Wei Xiang; Cheng, Qiang; Cui, Tie Jun

    2016-01-01

    One-dimensional (1D) subwavelength corrugated metal structures has been described to support spoof surface plasmon polaritons (SPPs). Here we demonstrate that a periodically modulated 1D subwavelength corrugated metal structure can convert spoof SPPs to propagating waves. The structure is fed at the center through a slit with a connected waveguide on the input side. The subwavelength corrugated metal structure on the output surface is regarded as metasurface and modulated periodically to realize the leaky-wave radiation at the broadside. The surface impedance of the corrugated metal structure is modulated by using cosine function and triangle-wave function, respectively, to reach the radiation effect. Full wave simulations and measuremental results are presented to validate the proposed design. PMID:27035269

  7. Bending Tests of Circular Cylinders of Corrugated Aluminum-alloy Sheet

    NASA Technical Reports Server (NTRS)

    Buckwalter, John C; Reed, Warren D; Niles, Alfred S

    1937-01-01

    Bending tests were made of two circular cylinders of corrugated aluminum-alloy sheet. In each test failure occurred by bending of the corrugations in a plane normal to the skin. It was found, after analysis of the effect of short end bays, that the computed stress on the extreme fiber of a corrugated cylinder is in excess of that for a flat panel of the same basic pattern and panel length tested as a pin-ended column. It is concluded that this increased strength was due to the effects of curvature of the pitch line. It is also concluded from the tests that light bulkheads closely spaced strengthen corrugated cylinders very materially.

  8. Leaky-Wave Radiations by Modulating Surface Impedance on Subwavelength Corrugated Metal Structures.

    PubMed

    Cai, Ben Geng; Li, Yun Bo; Ma, Hui Feng; Jiang, Wei Xiang; Cheng, Qiang; Cui, Tie Jun

    2016-04-01

    One-dimensional (1D) subwavelength corrugated metal structures has been described to support spoof surface plasmon polaritons (SPPs). Here we demonstrate that a periodically modulated 1D subwavelength corrugated metal structure can convert spoof SPPs to propagating waves. The structure is fed at the center through a slit with a connected waveguide on the input side. The subwavelength corrugated metal structure on the output surface is regarded as metasurface and modulated periodically to realize the leaky-wave radiation at the broadside. The surface impedance of the corrugated metal structure is modulated by using cosine function and triangle-wave function, respectively, to reach the radiation effect. Full wave simulations and measuremental results are presented to validate the proposed design.

  9. Numerical analysis of sandwich beam with corrugated core under three-point bending

    SciTech Connect

    Wittenbeck, Leszek; Grygorowicz, Magdalena; Paczos, Piotr

    2015-03-10

    The strength problem of sandwich beam with corrugated core under three-point bending is presented.The beam are made of steel and formed by three mutually orthogonal corrugated layers. The finite element analysis (FEA) of the sandwich beam is performed with the use of the FEM system - ABAQUS. The relationship between the applied load and deflection in three-point bending is considered.

  10. Field synergy analysis of six starts spiral corrugated tube under high Reynolds number

    NASA Astrophysics Data System (ADS)

    Qian, Jin-yuan; Liu, Bu-zhan; Chen, Fu-qiang; Gao, Xiao-fei; Jin, Zhi-jiang

    2016-09-01

    Coaxial heat exchanger is widely used in air conditioning, refrigeration etc., due to its highly efficient heat transfer performance. Spiral corrugated tube plays an important role in coaxial heat exchanger. In this paper, the numerical model of a six starts spiral corrugated tube and a smooth tube with the same size are developed. The temperature field and the velocity field of their streamline and longitudinal vortex are investigated respectively. Then, their heat transfer and pressure drop performance inside the spiral corrugated tube under different high Reynolds number is investigated by compared their Nusselt number and friction coefficient. Meanwhile, their field synergy performances with their field synergy angles are presented. The result shows that the Nusselt number and friction coefficient of spiral corrugated tube are always larger than the smooth tube, and with the increasing of Reynolds number, the heat transfer performance of SCT becomes better than smooth tube, however, the friction coefficient ratio also increases synchronously. And in spiral corrugated tube, the field synergy angel is smaller than in the smooth tube. This work can be referred by some who are also dealing with spiral corrugated tube and its heat performance research.

  11. Effect of track irregularities on initiation and evolution of rail corrugation

    NASA Astrophysics Data System (ADS)

    Jin, X. S.; Wen, Z. F.; Wang, K. Y.

    2005-07-01

    The effect of track irregularities on rail corrugation is investigated in detail with the numerical method when a wheelset is steadily curving. The irregularities considered in the analysis include initial running surface of rail with periodically varying and different wave length, stochastic roughness on the rail running surface, and vertical uneven support stiffness of the rail due to the discrete sleeper supports. The numerical method considers a combination of Kalker's rolling contact theory with non-Hertzian to be modified, a linear frictional work model and a vertical dynamics model of railway vehicle coupled with a curved track. The model is also validated by an experiment with a full scale facility. The influence of different speeds of wheelset curving on the development of the corrugation is taken into account in the calculation. The numerical results indicate that (1) for existing of the initial corrugation of new rail with any wavelength the depth from the peak to trough of it decreases gradually with an increase of wheelset passage, but the initial corrugation evolved has a tendency to move in the rolling direction, (2) the amplitude of the initial stochastic roughness of new rail is gradually leveled out and but a corrugation with very small depth and a few fixed passing frequencies is initiated, the passing frequencies are the same as the natural frequencies of the track, and (3) the discrete rail supports by sleepers have a great influence on the formation of the corrugation.

  12. Numerical analysis of bio-inspired corrugated airfoil at low Reynolds number

    NASA Astrophysics Data System (ADS)

    Mondal, Partha Protim; Rahman, Md. Masudur; Hasan, A. B. M. Toufique

    2016-07-01

    A numerical study was conducted to investigate the aerodynamic performance of a bio-inspired corrugated airfoil at the chord Reynolds number of Rec=80,000 to explore the potential advantages of such airfoils at low Reynolds numbers. This study represents the transient nature of corrugated airfoils at low Reynolds number where flow is assumed to be laminar, unsteady, incompressible and two dimensional. The simulations include a sharp interface Cartesian grid based meshing employed with laminar viscous model. The flow field surrounding the corrugated airfoil has been analyzed using structured grid Finite Volume Method (FVM) based on Navier-Stokes equation. All parameters used in flow simulation are expressed in non-dimensional quantities for better understanding of flow behavior, regardless of dimensions or the fluid that is used. The simulated results revealed that the corrugated airfoil provides high lift with moderate drag and prevents large scale flow separation at higher angles of attack. This happens due to the negative shear drag produced by the recirculation zones which occurs in the valleys of the corrugated airfoils. The existence of small circulation bubbles sitting in the valleys prevents large scale flow separation thus increasing the aerodynamic performance of the corrugated airfoil.

  13. Corrugated Quantum Well Infrared Photodetector Focal Plane Array Test Results

    NASA Technical Reports Server (NTRS)

    Goldberg, A.; Choi, K. K.; Das, N. C.; La, A.; Jhabvala, M.

    1999-01-01

    The corrugated quantum-well infrared photodetector (C-QWIP) uses total internal reflection to couple normal incident light into the optically active quantum wells. The coupling efficiency has been shown to be relatively independent of the pixel size and wavelength thus making the C-QWIP a candidate for detectors over the entire infrared spectrum. The broadband coupling efficiency of the C-QWIP makes it an ideal candidate for multiwavelength detectors. We fabricated and tested C-QWIP focal plane arrays (FPAs) with cutoff wavelengths of 11.2 and 16.2 micrometers. Each FPA has 256 x 256 pixels that are bump-bonded to a direct injection readout circuit. Both FPAs provided infrared imagery with good aesthetic attributes. For the 11.2-micrometers FPA, background-limited performance (BLIP) was observed at 60 K with f/3 optics. For the 16.2-micrometers FPA, BLIP was observed at 38 K. Besides the reduction of dark current in C-QWIP structures, the measured internal quantum efficiency (eta) remains to be high. The values for responsivity and quantum efficiency obtained from the FPA results agree well with those measured for single devices.

  14. Terahertz radiation from a pipe with small corrugations

    NASA Astrophysics Data System (ADS)

    Bane, K. L. F.; Stupakov, G.

    2012-06-01

    We have studied through analytical and numerical methods the use of a relativistic electron bunch to drive a metallic beam pipe with small corrugations for the purpose of generating terahertz radiation. For the case of a pipe with dimensions that do not change along its length, we have shown that—with reasonable parameters—one can generate a narrow-band radiation pulse with frequency ˜1 THz, and total energy of a few milli-Joules. The pulse length tends to be on the order of tens of picoseconds. We have also shown that, if the pipe radius is tapered along its length, the generated pulse will end up with a frequency chirp; if the pulse is then made to pass through a compressor, its final length can be reduced to a few picoseconds and its peak power increased to ˜1 GW. We have also shown that wall losses tend to be significant and need to be included in the structure design.

  15. Superradiance of short electron pulses in regular and corrugated waveguides

    SciTech Connect

    Ginzburg, N.S.; Konoplev, I.V.; Sergeev, A.S.

    1995-12-31

    The report is devoted to theoretical and experimental study of superradiance of short electron pulses moving through waveguide systems. It is suggested that electrons oscillate or in undulator field (undulator SR) or in homogeneous magnetic field (cyclotron SR). We studied specific regimes of SR which may occur due to peculiarities of waveguide dispersion. Among them there are regimes of radiation near cut-off frequency as well as regimes of group synchronism. At the last operating regimes an electron bunch longitudinal velocity coincide with group velocity of e.m. wave. It is found the increasing of the SR instability grows rate and energy extraction efficiency in such regimes. It is also possible to observe the same enhancement using external feedback in periodically corrugated waveguide when Bragg resonance condition with forward propagated e.m. wave is fulfill. For experimental observation of cyclotron SR we intend to use compact subnanosecond accelerator RADAN 303B on the base of the high voltage generator with special subnansecond transformer. Accelerator generates short 0.3ns electron pulses with current about 1kA and particles energy 200keV. Design of magnetic confound system provide possibility to install an active locker to impose to electrons cyclotron rotation with pitch-factor about 1-1.5. According to numerical simulation at the mm and submm wavebands it is possible to achieve radiation pick power about 5-10MW with pulse duration less than 1ns.

  16. Dispersionless Manipulation of Reflected Acoustic Wavefront by Subwavelength Corrugated Surface

    PubMed Central

    Zhu, Yi-Fan; Zou, Xin-Ye; Li, Rui-Qi; Jiang, Xue; Tu, Juan; Liang, Bin; Cheng, Jian-Chun

    2015-01-01

    Free controls of optic/acoustic waves for bending, focusing or steering the energy of wavefronts are highly desirable in many practical scenarios. However, the dispersive nature of the existing metamaterials/metasurfaces for wavefront manipulation necessarily results in limited bandwidth. Here, we propose the concept of dispersionless wavefront manipulation and report a theoretical, numerical and experimental work on the design of a reflective surface capable of controlling the acoustic wavefront arbitrarily without bandwidth limitation. Analytical analysis predicts the possibility to completely eliminate the frequency dependence with a specific gradient surface which can be implemented by designing a subwavelength corrugated surface. Experimental and numerical results, well consistent with the theoretical predictions, have validated the proposed scheme by demonstrating a distinct phenomenon of extraordinary acoustic reflection within an ultra-broad band. For acquiring a deeper insight into the underlying physics, a simple physical model is developed which helps to interpret this extraordinary phenomenon and predict the upper cutoff frequency precisely. Generations of planar focusing and non-diffractive beam have also been exemplified. With the dispersionless wave-steering capability and deep discrete resolution, our designed structure may open new avenue to fully steer classical waves and offer design possibilities for broadband optical/acoustical devices. PMID:26077772

  17. Corrugator activity confirms immediate negative affect in surprise

    PubMed Central

    Topolinski, Sascha; Strack, Fritz

    2015-01-01

    The emotion of surprise entails a complex of immediate responses, such as cognitive interruption, attention allocation to, and more systematic processing of the surprising stimulus. All these processes serve the ultimate function to increase processing depth and thus cognitively master the surprising stimulus. The present account introduces phasic negative affect as the underlying mechanism responsible for this switch in operating mode. Surprising stimuli are schema-discrepant and thus entail cognitive disfluency, which elicits immediate negative affect. This affect in turn works like a phasic cognitive tuning switching the current processing mode from more automatic and heuristic to more systematic and reflective processing. Directly testing the initial elicitation of negative affect by surprising events, the present experiment presented high and low surprising neutral trivia statements to N = 28 participants while assessing their spontaneous facial expressions via facial electromyography. High compared to low surprising trivia elicited higher corrugator activity, indicative of negative affect and mental effort, while leaving zygomaticus (positive affect) and frontalis (cultural surprise expression) activity unaffected. Future research shall investigate the mediating role of negative affect in eliciting surprise-related outcomes. PMID:25762956

  18. Dispersionless Manipulation of Reflected Acoustic Wavefront by Subwavelength Corrugated Surface.

    PubMed

    Zhu, Yi-Fan; Zou, Xin-Ye; Li, Rui-Qi; Jiang, Xue; Tu, Juan; Liang, Bin; Cheng, Jian-Chun

    2015-06-16

    Free controls of optic/acoustic waves for bending, focusing or steering the energy of wavefronts are highly desirable in many practical scenarios. However, the dispersive nature of the existing metamaterials/metasurfaces for wavefront manipulation necessarily results in limited bandwidth. Here, we propose the concept of dispersionless wavefront manipulation and report a theoretical, numerical and experimental work on the design of a reflective surface capable of controlling the acoustic wavefront arbitrarily without bandwidth limitation. Analytical analysis predicts the possibility to completely eliminate the frequency dependence with a specific gradient surface which can be implemented by designing a subwavelength corrugated surface. Experimental and numerical results, well consistent with the theoretical predictions, have validated the proposed scheme by demonstrating a distinct phenomenon of extraordinary acoustic reflection within an ultra-broad band. For acquiring a deeper insight into the underlying physics, a simple physical model is developed which helps to interpret this extraordinary phenomenon and predict the upper cutoff frequency precisely. Generations of planar focusing and non-diffractive beam have also been exemplified. With the dispersionless wave-steering capability and deep discrete resolution, our designed structure may open new avenue to fully steer classical waves and offer design possibilities for broadband optical/acoustical devices.

  19. Corrugated quantum well infrared photodetectors for far infrared detection

    NASA Astrophysics Data System (ADS)

    Choi, Kwong-Kit; Jhabvala, Murzy D.; Forrai, David; Sun, Jason; Endres, Darrel

    2011-06-01

    We have extended our investigation of corrugated quantum well infrared photodetector focal plane arrays (FPAs) into the far infrared regime. Specifically, we are developing the detectors for the thermal infrared sensor (TIRS) used in the Landsat Data Continuity Mission. To maintain a low dark current, we adopted a low doping density of 0.6×1018 cm-3 and a bound-to-bound state detector. The internal absorption quantum efficiency (QE) is calculated to be 25.4%. With a pixel fill factor of 80% and a substrate transmission of 70.9%, the external QE is 14.4%. To yield the theoretical conversion efficiency (CE), the photoconductive gain was measured and is 0.25 at 5 V, from which CE is predicted to be 3.6%. This value is in agreement with the 3.5% from the FPA measurement. Meanwhile, the dark current is measured to be 2.1×10-6 A/cm2 at 43 K. For regular infrared imaging above 8 μm, the FPA will have an noise equivalent temperature difference (NETD) of 16 mK at 2 ms integration time in the presence of 260 read noise electrons. The highest operability of the tested FPAs is 99.967%. With the CE agreement, we project the FPA performance in the far infrared regime up to 30 μm cutoff.

  20. Driving corrugated donut rotors with Laguerre-Gauss beams.

    PubMed

    Loke, Vincent L Y; Asavei, Theodor; Stilgoe, Alexander B; Nieminen, Timo A; Rubinsztein-Dunlop, Halina

    2014-08-11

    Tightly-focused laser beams that carry angular momentum have been used to trap and rotate microrotors. In particular, a Laguerre-Gauss mode laser beam can be used to transfer its orbital angular momentum to drive microrotors. We increase the torque efficiency by a factor of about 2 by designing the rotor such that its geometry is compatible with the driving beam, when driving the rotation with the optimum beam, rather than beams of higher or lower orbital angular momentum. Based on Floquet's theorem, the order of discrete rotational symmetry of the rotor can be made to couple with the azimuthal mode of the Laguerre-Gauss beam. We design corrugated donut rotors, that have a flat disc-like profile, with the help of the discrete dipole approximation and the T-matrix methods in parallel with experimental demonstrations of stable trapping and torque measurement. We produce and test such a rotor using two-photon photopolymerization. With a rotor that has 8-fold discrete rotational symmetry, an outer radius of 1.85 μm and a hollow core radius of 0.5 μm, we were able to transfer approximately 0.3 h̄ per photon of the orbital angular momentum from an LG04 beam.

  1. Adsorption of "soft" spherical particles onto sinusoidally-corrugated substrates.

    PubMed

    Schoch, Phillip K; Genzer, Jan

    2014-10-14

    We utilize a Monte Carlo simulation scheme based on the bond fluctuation model to simulate settlement of "soft" adhesive particles onto sinusoidally-corrugated substrates. Particles are composed of a hard inner core with a "soft" adhesive shell made of surface-grafted polymer chains. These chains adhere to surface lattice sites via pair wise non-specific interactions acting between the substrate and the last two segments of the polymer grafts on the particle. This simulation scheme is aimed at comprehending single particle adsorption behavior to find the highest adhesion energy locations for given test surfaces and elucidate test surfaces that reduce adhesion energy. Parameters in this study are set by the particle, the substrate and an interaction parameter between the two. Particle parameters include core diameter (D), grafting density of polymer (σ) and length of grafted polymer (N). Substrate parameters include wavelength (λ) and amplitude (A). Our results show that the wavelength of substrate features plays a significant role in the settlement of single particle systems. At λ = D/2 we observe a minimum in the adhesion energy and at λ = D we observe a uniform settlement location of the particles. Increasing N leads to a reduction in the effectiveness of substrate topography to direct the settlement of individual particles into specific sites on the substrate.

  2. Dispersionless Manipulation of Reflected Acoustic Wavefront by Subwavelength Corrugated Surface

    NASA Astrophysics Data System (ADS)

    Zhu, Yi-Fan; Zou, Xin-Ye; Li, Rui-Qi; Jiang, Xue; Tu, Juan; Liang, Bin; Cheng, Jian-Chun

    2015-06-01

    Free controls of optic/acoustic waves for bending, focusing or steering the energy of wavefronts are highly desirable in many practical scenarios. However, the dispersive nature of the existing metamaterials/metasurfaces for wavefront manipulation necessarily results in limited bandwidth. Here, we propose the concept of dispersionless wavefront manipulation and report a theoretical, numerical and experimental work on the design of a reflective surface capable of controlling the acoustic wavefront arbitrarily without bandwidth limitation. Analytical analysis predicts the possibility to completely eliminate the frequency dependence with a specific gradient surface which can be implemented by designing a subwavelength corrugated surface. Experimental and numerical results, well consistent with the theoretical predictions, have validated the proposed scheme by demonstrating a distinct phenomenon of extraordinary acoustic reflection within an ultra-broad band. For acquiring a deeper insight into the underlying physics, a simple physical model is developed which helps to interpret this extraordinary phenomenon and predict the upper cutoff frequency precisely. Generations of planar focusing and non-diffractive beam have also been exemplified. With the dispersionless wave-steering capability and deep discrete resolution, our designed structure may open new avenue to fully steer classical waves and offer design possibilities for broadband optical/acoustical devices.

  3. Responses of buried corrugated metal pipes to earthquakes

    SciTech Connect

    Davis, C.A.; Bardet, J.P.

    2000-01-01

    This study describes the results of field investigations and analyses carried out on 61 corrugated metal pipes (CMP) that were shaken by the 1994 Northridge earthquake. These CMPs, which include 29 small-diameter (below 107 cm) CMPs and 32 large-diameter (above 107 cm) CMPs, are located within a 10 km{sup 2} area encompassing the Van Normal Complex in the Northern San Fernando Valley, in Los Angeles, California. During the Northridge earthquake, ground movements were extensively recorded within the study area. Twenty-eight of the small-diameter CMPs performed well while the 32 large-diameter CMPs underwent performances ranging from no damage to complete collapse. The main cause of damage to the large-diameter CMPs was found to be the large ground strains. Based on this unprecedented data set, the factors controlling the seismic performance of the 32 large-diameter CMPs were identified and framed into a pseudostatic analysis method for evaluating the response of large diameter flexible underground pipes subjected to ground strain. The proposed analysis, which is applicable to transient and permanent strains, is capable of describing the observed performance of large-diameter CMPs during the 1994 Northridge earthquake. It indicates that peak ground velocity is a more reliable parameter for analyzing pipe damage than is peak ground acceleration. Results of this field investigation and analysis are useful for the seismic design and strengthening of flexible buried conduits.

  4. Analysis of Doubly Corrugated Spoof Surface Plasmon Polariton (DC-SSPP) Structure With Sub-Wavelength Transmission at THz Frequencies

    DTIC Science & Technology

    2012-05-08

    electromagnetic waves which propagate on the periodically corrugated metal surface at frequencies outside the conventional plasmonic spectrum of metals . The...polariton propagation and focusing on pe- riodically corrugated metal wires,” Phys. Rev. Lett., vol. 97, p. 176805, 2006. [22] Q. Gan, Z. Fu, Y. J...0188 3. DATES COVERED (From - To) - UU UU UU UU Approved for public release; distribution is unlimited. Analysis of Doubly Corrugated Spoof

  5. Heat transfer enhancement and pumping power optimization using CuO-water nanofluid through rectangular corrugated pipe

    NASA Astrophysics Data System (ADS)

    Salehin, Musfequs; Ehsan, Mohammad Monjurul; Islam, A. K. M. Sadrul

    2017-06-01

    Heat transfer enhancement by corrugation in fluid domain is a popular method. The rate of improvement is more when it is used highly thermal conductive fluid as heating or cooling medium. In this present study, heat transfer augmentation was investigated numerically by implementing corrugation in the fluid domain and nanofluid as the base fluid in the turbulent forced convection regime. Finite volume method (FVM) was applied to solve the continuity, momentum and energy equations. All the numerical simulations were considered for single phase flow. A rectangle corrugated pipe with 5000 W/m2 constant heat flux subjected to the corrugated wall was considered as the fluid domain. In the range of Reynolds number 15000 to 40000, thermo-physical and hydrodynamic behavior was investigated by using CuO-water nanofluid from 1% to 5% volume fraction as the base fluid through the corrugated fluid domain. Corrugation justification was performed by changing the amplitude of the corrugation and the corrugation wave length for obtaining the increased heat transfer rate with minimum pumping power. For using CuO-water nanofluid, augmentation was also found more in the rectangle corrugated pipe both in heat transfer and pumping power requirement with the increase of Reynolds number and the volume fraction of nanofluid. For the increased pumping power, optimization of pumping power by using nanofluid was also performed for economic finding.

  6. Experimental investigation on the convective heat transfer enhancement in tubes with cross-helix profile wall corrugation

    NASA Astrophysics Data System (ADS)

    Cattani, L.; Bozzoli, F.; Rainieri, S.; Pagliarini, G.

    2017-01-01

    Wall corrugation is a popular heat transfer enhancement technique since it acts as a disturbance source in the flow that significantly enhances the thermal performance of the tube section with a limited pressure drop augmentation if compared to other passive techniques, such as the ones based on insert devices. In the hereby presented study nine pipes characterised by a cross-helix type corrugation were tested: this kind of corrugation, that was obtained by rolling twice the same tube with two helical corrugations evolving along opposite directions, showed a performance that exceeded the single helix-type corrugation behaviour and moreover presented an earlier transition to unstable regime. In the analysis the effect of the cross-helix type corrugation profile on the forced convection heat transfer mechanism was experimentally investigated in the Reynolds and Prandtl number range 25÷1000 and 115÷150 respectively. In particular, the effect of both the corrugation depth and the corrugation pitch were analysed. The results were compared with other types of wall corrugation and with the predictions for the smooth tube in order to point out the achieved heat transfer enhancement.

  7. Plastics Technology.

    ERIC Educational Resources Information Center

    Barker, Tommy G.

    This curriculum guide is designed to assist junior high schools industrial arts teachers in planning new courses and revising existing courses in plastics technology. Addressed in the individual units of the guide are the following topics: introduction to production technology; history and development of plastics; safety; youth leadership,…

  8. Plastics Technology.

    ERIC Educational Resources Information Center

    Barker, Tommy G.

    This curriculum guide is designed to assist junior high schools industrial arts teachers in planning new courses and revising existing courses in plastics technology. Addressed in the individual units of the guide are the following topics: introduction to production technology; history and development of plastics; safety; youth leadership,…

  9. The linear stability of a core annular flow in an asymptotically corrugated tube

    NASA Astrophysics Data System (ADS)

    Wei, Hsien-Hung; Rumschitzki, David S.

    2002-09-01

    This paper examines the core annular flow of two immiscible fluids in a straight circular tube with a small corrugation, in the limit where the ratio [epsilon] of the mean undisturbed annulus thickness to the mean core radius and the corrugation (characterized by the parameter [sigma]) are both asymptotically small and where the surface tension is small. It is motivated by the problems of liquid liquid displacement in irregular rock pores such as occur in secondary oil recovery and in the evolution of the liquid film lining the bronchii in the lungs whose diameters vary over different generations of branching. We investigate the asymptotic base flow in this limit and consider the linear stability of its leading order (in the corrugation parameter) solution. For the chosen scalings of the non-dimensional parameters the core's base flow slaves that of the annulus. The equation governing the leading-order interfacial position for a given wall corrugation function shows a competition between shear and capillarity. The former tends to align the interface shape with that of the wall and the latter tends to introduce a phase shift, which can be of either sign depending on whether the circumferential or the longitudinal component of capillarity dominates. The asymptotic linear stability of this leading-order base flow reduces to a single partial differential equation with non-constant coefficients deriving from the non-uniform base flow for the time evolution of an interfacial disturbance. Examination of a single mode k wall function allows the use of Floquet theory to analyse this equation. Direct numerical solutions of the above partial differential equation agree with the predictions of the Floquet analysis. The resulting spectrum is periodic in [alpha]- space, [alpha] being the disturbance wavenumber space. The presence of a small corrugation not only modifies (at order [sigma]2) the primary eigenvalue of the system. In addition, short-wave order-one disturbances that

  10. Optomechanic interaction in a corrugated phoxonic nanobeam cavity

    NASA Astrophysics Data System (ADS)

    Oudich, Mourad; El-Jallal, Said; Pennec, Yan; Djafari-Rouhani, Bahram; Gomis-Bresco, Jordi; Navarro-Urrios, Daniel; Sotomayor Torres, Clivia M.; Martínez, Alejandro; Makhoute, Abdelkader

    2014-06-01

    The interaction between phonons and photons is investigated theoretically in a phoxonic cavity inside a corrugated nanobeam waveguide presenting band gaps for both electromagnetic and elastic waves. The structure is made by drilling periodic holes on a silicon nanobeam with lateral periodic stubs and the tapered cavity is constructed by changing gradually the geometrical parameters of both the holes and stubs. We show that this kind of cavity displays localized phonons and photons inside the gaps, which can enhance their interaction and also promotes the presence of many optical confined modes with high quality factor. Using the finite-element method, we demonstrate that with appropriate design of the tapering construction, one can control the cavity modes frequency without altering significantly the quality factor of the photonic modes. By changing the tapering rates over the lattice constants, we establish the possibility of shifting the phononic cavity modes frequency to place them inside the desired gap, which enhances their confinement and increases the mechanical quality factor while keeping the strength of the optomechanic coupling high. In our calculations, we take account of both mechanisms that contribute to the acousto-optic interaction, namely photoelastic and interface motion effects. We show that in our case, these two effects can contribute additively to give high coupling strength between phononic and photonic cavity modes. The calculations of the coupling coefficient which gives the phonon-photon coupling strength give values as high as 2 MHz while photonic cavity modes display quality factor of 105 and even values up to 3.4 MHz but with smaller photonic quality factors.

  11. Heat transfer and fluid flow behaviors in a five-start spiral corrugated tube

    NASA Astrophysics Data System (ADS)

    Promthaisong, Pitak; Jedsadaratanachai, Withada; Chuwattanakul, Varesa; Eiamsa-ard, Smith

    2017-08-01

    This paper presented a numerical investigation on turbulent periodic flow, heat transfer, pressure loss and thermal enhancement factor in a 3D five-start spiral corrugated tube. Air was used as the working fluids through the tube for Reynolds numbers of about 5000-20,000. In the current studied, the five-start spiral corrugated tube with six relative pitch ratios (p/D, PR=1.0, 1.5, 2.0, 2.5, 3.0 and 3.5) with constant depth ratio (e/D, DR=0.06). The numerical results reveal that the five-start spiral corrugated tube can generated a swirl flow, main swirl flow and five-secondary swirl flow. This behavior lead to the major change of temperature in transverse plane, reduced thermal layer thickness and enhanced heat transfer on the tube wall. The five-start spiral corrugated tube in range investigated provided the heat transfer rate and friction factor up to 2.02 and 6.12 times, respectively, over the straight circular tube. The thermal enhancement factor of the five-start spiral corrugated tube in the range of 0.89-1.16 where its maximum found as the optimum point is at PR=2.0.

  12. Hollow fiber membranes with different external corrugated surfaces for desalination by membrane distillation

    NASA Astrophysics Data System (ADS)

    García-Fernández, Loreto; García-Payo, Carmen; Khayet, Mohamed

    2017-09-01

    Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) hollow fiber membranes were prepared using the phase inversion spinning technique under a wet gap mode. Different corrugated outer surfaces were obtained by means of a micro-engineered spinneret, spraying the external coagulant on the nascent fiber along gap, and different spinning parameters, namely, the gap distance and the external coagulant flow rate. A quantitative evaluation of the corrugation size and shape was carried out by electron scanning microscopy and atomic force microscopy. The effect of the corrugation size and shape on the direct contact membrane distillation (DCMD) performance has been studied. The corrugated outer surface acted as micro-turbulence promoters mitigating the temperature polarization effect and enhanced the external effective surface area for condensation. Both factors improved the DCMD permeability of the hollow fiber membranes. However, corrugations with V-shaped valleys depths greater than about 30 μm did not always improve the DCMD permeate flux. It was found that the membrane prepared with the spray wetting mode exhibited the best desalination performance. The salt rejection factor of all prepared hollow fiber membranes was greater than 99.9% and the highest DCMD permeate flux of this study was greater than those reported so far for the PVDF-HFP hollow fiber membranes.

  13. Models for New Corrugated and Porous Solar Air Collectors under Transient Operation

    NASA Astrophysics Data System (ADS)

    Adnan Abed, Qahtan; Badescu, Viorel; Ciocanea, Adrian; Soriga, Iuliana; Bureţea, Dorin

    2017-01-01

    Mathematical models have been developed to evaluate the dynamic behavior of two solar air collectors: the first one is equipped with a V-porous absorber and the second one with a U-corrugated absorber. The collectors have the same geometry, cross-section surface area and are built from the same materials, the only difference between them being the absorbers. V-corrugated absorbers have been treated in literature but the V-porous absorbers modeled here have not been very often considered. The models are based on first-order differential equations which describe the heat exchange between the main components of the two types of solar air heaters. Both collectors were exposed to the sun in the same meteorological conditions, at identical tilt angle and they operated at the same air mass flow rate. The tests were carried out in the climatic conditions of Bucharest (Romania, South Eastern Europe). There is good agreement between the theoretical results and experiments. The average bias error was about 7.75 % and 10.55 % for the solar air collector with "V"-porous absorber and with "U"-corrugated absorber, respectively. The collector based on V-porous absorber has higher efficiency than the collector with U-corrugated absorber around the noon of clear days. Around sunrise and sunset, the collector with U-corrugated absorber is more effective.

  14. Linear analysis of a backward wave oscillator with triangular corrugated slow wave structure

    NASA Astrophysics Data System (ADS)

    Saber, Md. Ghulam; Sagor, Rakibul Hasan; Amin, Md. Ruhul

    2016-05-01

    In this work, a backward wave oscillator (BWO) with triangularly corrugated periodic metallic slow wave structure (TrCSWS) driven by an infinitely thin annular electron beam is studied using linear theory. The electron beam is assumed to be guided by a strong magnetic field. The triangular axial profile of the SWS is approximated by a Fourier series in order to apply the linear Rayleigh-Fourier (R-F) theory that has long been used in the theoretical analysis of BWOs with sinusoidally corrugated SWS (SCSWS). The dispersion equation for various beam parameters has been solved and the temporal growth rate (TGR) of the electromagnetic wave for the fundamental TM_{01} mode is calculated numerically. The TGR values for different beam parameters have been compared with those of the BWO with SCSWS, semi-circularly corrugated SWS (SCCSWS) and trapezoidally corrugated SWS (TCSWS). In order to compare the TGR values, the amplitude of corrugation of the TrCSWS is varied so that its dispersion curve of TM_{01} mode almost coincides with that of the SCSWS and TCSWS. The study reveals that the performance (in terms of TGR) of the proposed BWO with TrCSWS is comparable to that of other BWOs with SCSWS and TCSWS for the same set of beam parameters and it provides significantly better performance than SCCSWS. So, the proposed TrCSWS that can easily be constructed may replace SCSWS, SCCSWS or TCSWS as their viable alternative.

  15. Plastic welder

    NASA Technical Reports Server (NTRS)

    Buckley, J. D.; Fox, R. L.; Swain, R. J.

    1980-01-01

    Low-cost, self-contained, portable welder joins plastic parts by induction heating. Welder is useable in any atmosphere or in vacuum and with most types of thermoplastic; plastic components can be joined in situ. Device is applicable to aerospace industry and in automobile, furniture, and construction industries. Power requirements are easily met by battery or solar energy. In welder, toroidal inductor transfers magnetic flux through thermoplastic to screen. Heated screen causes plastic surface on either side to melt and flow into it to form joint.

  16. Impact-damaged graphite-thermoplastic trapezoidal-corrugation sandwich and semi-sandwich panels

    NASA Technical Reports Server (NTRS)

    Jegley, D.

    1993-01-01

    The results of a study of the effects of impact damage on compression-loaded trapezoidal-corrugation sandwich and semi-sandwich graphite-thermoplastic panels are presented. Sandwich panels with two identical face sheets and a trapezoidal corrugated core between them, and semi-sandwich panels with a corrugation attached to a single skin are considered in this study. Panels were designed, fabricated and tested. The panels were made using the manufacturing process of thermoforming, a less-commonly used technique for fabricating composite parts. Experimental results for unimpacted control panels and panels subjected to impact damage prior to loading are presented. Little work can be found in the literature about these configurations of thermoformed panels.

  17. Impact-damaged graphite-thermoplastic trapezoidal-corrugation sandwich and semi-sandwich panels

    NASA Astrophysics Data System (ADS)

    Jegley, D.

    1993-01-01

    The results of a study of the effects of impact damage on compression-loaded trapezoidal-corrugation sandwich and semi-sandwich graphite-thermoplastic panels are presented. Sandwich panels with two identical face sheets and a trapezoidal corrugated core between them, and semi-sandwich panels with a corrugation attached to a single skin are considered in this study. Panels were designed, fabricated and tested. The panels were made using the manufacturing process of thermoforming, a less-commonly used technique for fabricating composite parts. Experimental results for unimpacted control panels and panels subjected to impact damage prior to loading are presented. Little work can be found in the literature about these configurations of thermoformed panels.

  18. Two-color corrugated quantum-well infrared photodetector for remote temperature sensing

    NASA Astrophysics Data System (ADS)

    Chen, C. J.; Choi, K. K.; Chang, W. H.; Tsui, D. C.

    1998-01-01

    A quantum-well infrared photodetector (QWIP) based on the corrugated light-coupling scheme has been fabricated and tested for remote temperature sensing. The QWIP consists of two stacks of multiple quantum wells (MQWs), each sensitive in one of the atmospheric infrared transmission windows and each with a separate readout circuit. High optical coupling efficiency is obtained in both wavelength ranges, demonstrating the use of the corrugated structure for two-color detection. By monitoring the ratio of the photocurrent generated simultaneously in each MQW stack, the temperature of the object emitting the radiation can be determined, regardless of its emissivity and the geometrical factors. This temperature sensing ability is tested by using a blackbody radiator with precision temperature control as the target. The agreement between the measured and the preset temperatures indicates that the corrugated QWIP is capable of precision thermometric measurements.

  19. Trapping of surface plasmon wave through gradient corrugated strip with underlayer ground and manipulating its propagation

    NASA Astrophysics Data System (ADS)

    Zhang, Wenjuan; Zhu, Guiqiang; Sun, Liguo; Lin, Fujiang

    2015-01-01

    Corrugated metal surface with underlayer metal as ground is designed as spoof surface plasmons polaritons (SSPPs) structure in microwave frequencies. Efficient conversion from guided wave to SSPP is required for energy feeding into and signal extracting from such plasmonic structure. In this paper, first a high efficient transition design is presented by using gradient corrugated strip with underlayer metal as ground and by using the impedance matching theory. The SSPP wave is highly confined within the teeth part of the corrugated surface. By using this characteristic, then the simple wire-based metamaterial is added below the strip to manipulate the SSPP wave within the propagating band. Two aforementioned devices are designed and fabricated. The simulated and measured results on the scattering coefficients demonstrate the excellent conversion and excellent manipulating of SSPP transmitting. Such results have very important value to develop advanced plasmonic integrated circuits in the microwave frequencies.

  20. Two-color corrugated quantum-well infrared photodetector for remote temperature sensing

    SciTech Connect

    Chen, C.J.; Choi, K.K.; Chang, W.H.; Tsui, D.C.

    1998-01-01

    A quantum-well infrared photodetector (QWIP) based on the corrugated light-coupling scheme has been fabricated and tested for remote temperature sensing. The QWIP consists of two stacks of multiple quantum wells (MQWs), each sensitive in one of the atmospheric infrared transmission windows and each with a separate readout circuit. High optical coupling efficiency is obtained in both wavelength ranges, demonstrating the use of the corrugated structure for two-color detection. By monitoring the ratio of the photocurrent generated simultaneously in each MQW stack, the temperature of the object emitting the radiation can be determined, regardless of its emissivity and the geometrical factors. This temperature sensing ability is tested by using a blackbody radiator with precision temperature control as the target. The agreement between the measured and the preset temperatures indicates that the corrugated QWIP is capable of precision thermometric measurements. {copyright} {ital 1998 American Institute of Physics.}

  1. Effects of corrugation angle on developing laminar forced convection and entropy generation in a wavy channel

    NASA Astrophysics Data System (ADS)

    Ko, Tzu-Hsiang

    2007-12-01

    This paper investigates the effects of corrugation angle ( β) on the developing laminar forced convection and entropy generation in a wavy channel with numerical methods. The studied cases cover β = 10-, 15-, 20-, 25-, 30- and 35°, whilst Reynolds number ( Re) is varied as 100, 200 and 400. The analyzed flow characteristics include recirculating flows, secondary vortices, temperature distributions, and friction factor as well as Nusselt number. In particular, the effects of corrugation angle on the distributions and magnitudes of local entropy generation resulted from frictional irreversibility ( S {/P '''}) and heat transfer irreversibility ( S {/T '''}) are separately discussed in detail in the present paper. Based on the minimal entropy generation principle, the optimal corrugation angle and favorable Re are reported.

  2. Theoretical investigation on guiding IR light in hollow-core metallic fiber with corrugated inner surface.

    PubMed

    Liu, Hairong; Yan, Min; Qiu, Min; Liu, Deming; Yu, Xia; Zhang, Ying

    2010-10-11

    Hollow metallic fibers (HMFs) are in general lossy primarily owing to the fact that the guided transverse-magnetic (TM) light sustains a relatively high propagation loss. In this paper, we propose a type of practical hollow-core metallic fiber (HMF) with longitudinally corrugated inner surface for transmitting infrared (IR) light. Simulation results show that the loss of the fundamental TM mode can be easily reduced by 50~100 times compared to a HMF without surface corrugation. In contrast to the traditional HMF with a dielectric coating, it is shown that the loss of the fundamental TM mode in the proposed HMF is relatively insensitive to the corrugation layer thickness or equivalently the operating frequency.

  3. Electromagnetohydrodynamic (EMHD) micropump of Jeffrey fluids through two parallel microchannels with corrugated walls

    NASA Astrophysics Data System (ADS)

    Si, Dongqing; Jian, Yongjun

    2015-03-01

    By employing the perturbation method, the approximate analytical solutions of velocity and volume flow rate are presented for electromagnetohydrodynamic (EMHD) flow of an electrically conducting, incompressible and viscous Jeffrey fluid between two slit microparallel plates with corrugated walls. The corrugations of the two walls are described as periodic sinusoidal waves with small amplitude either in phase or half-period out of phase. The effects of the corrugations on the EMHD flow velocity are analyzed by using numerical computation. The variations of velocity profiles and mean velocity parameter and their dependences on the Reynolds number Re, Hartmann number Ha, dimensionless wave number λ of the wall perturbation, the dimensionless relaxation time λ1ω and retardation time λ2ω are explained graphically.

  4. A Simple Experiment to Explore Standing Waves in a Flexible Corrugated Sound Tube

    NASA Astrophysics Data System (ADS)

    Amorim, Maria Eva; Sousa, Teresa Delmira; Carvalho, P. Simeão; Sousa, Adriano Sampaioe

    2011-09-01

    Sound tubes, pipes, and singing rods are used as musical instruments and as toys to perform amusing experiments. In particular, corrugated tubes present unique characteristics with respect to the sounds they can produce; that is why they have been studied so intensively, both at theoretical and experimental levels.1-4 Experimental studies usually involve expensive and sophisticated equipment that is out of reach of school laboratory facilities.3-6 In this paper we show how to investigate quantitatively the sounds produced by a flexible sound tube corrugated on the inside by using educational equipment readily available in school laboratories, such as the oscilloscope, the microphone, the anemometer, and the air pump. We show that it is possible for students to study the discontinuous spectrum of sounds produced by a flexible corrugated tube and go even further, computing the speed of sound in air with a simple experimental procedure.

  5. The anatomy of the corrugator supercilii muscle: part II. Supraorbital nerve branching patterns.

    PubMed

    Janis, Jeffrey E; Ghavami, Ashkan; Lemmon, Joshua A; Leedy, Jason E; Guyuron, Bahman

    2008-01-01

    This article focuses on delineation of supraorbital nerve branching patterns relative to the corrugator muscle fibers and identifies four branching patterns that help improve understanding of the local anatomy. Twenty-five fresh cadaver heads (50 corrugator supercilii muscles and 50 supraorbital nerves) were dissected and the corrugator supercilii muscles isolated. After corrugator supercilii muscle measurement points were recorded for part I of the study, the supraorbital nerve branches were then traced from their emergence points from the orbit and dissected out to the defined topographical boundaries of the muscle. Nerve branching patterns relative to the muscle fibers were analyzed, and a classification system for branching patterns relative to the muscle was created. Four types of supraorbital nerve branching patterns were found. In type I (40 percent), only the deep supraorbital nerve division sent branches that coursed directly along the undersurface of the muscle. In type II (34 percent), branches emerging directly from the superficial supraorbital nerve were found in addition to the branches from the deep division. Type III (4 percent) included discrete branches from the superficial division, but none from the deep division. In type IV (22 percent), significant branching began more cephalad relative to the muscle and, therefore, displayed no specific relation to the muscle fibers. Contrary to previous reports, both the deep and superficial divisions of the supraorbital nerve are intimately associated with corrugator supercilii muscle fibers. Four supraorbital nerve branching patterns from these divisions were found. Potential sites of supraorbital nerve compression were identified. This more detailed anatomical information may improve the safety and accuracy of performing complete corrugator supercilii muscle resection.

  6. Spatial Stereoresolution for Depth Corrugations May Be Set in Primary Visual Cortex

    PubMed Central

    Allenmark, Fredrik; Read, Jenny C. A.

    2011-01-01

    Stereo “3D” depth perception requires the visual system to extract binocular disparities between the two eyes' images. Several current models of this process, based on the known physiology of primary visual cortex (V1), do this by computing a piecewise-frontoparallel local cross-correlation between the left and right eye's images. The size of the “window” within which detectors examine the local cross-correlation corresponds to the receptive field size of V1 neurons. This basic model has successfully captured many aspects of human depth perception. In particular, it accounts for the low human stereoresolution for sinusoidal depth corrugations, suggesting that the limit on stereoresolution may be set in primary visual cortex. An important feature of the model, reflecting a key property of V1 neurons, is that the initial disparity encoding is performed by detectors tuned to locally uniform patches of disparity. Such detectors respond better to square-wave depth corrugations, since these are locally flat, than to sinusoidal corrugations which are slanted almost everywhere. Consequently, for any given window size, current models predict better performance for square-wave disparity corrugations than for sine-wave corrugations at high amplitudes. We have recently shown that this prediction is not borne out: humans perform no better with square-wave than with sine-wave corrugations, even at high amplitudes. The failure of this prediction raised the question of whether stereoresolution may actually be set at later stages of cortical processing, perhaps involving neurons tuned to disparity slant or curvature. Here we extend the local cross-correlation model to include existing physiological and psychophysical evidence indicating that larger disparities are detected by neurons with larger receptive fields (a size/disparity correlation). We show that this simple modification succeeds in reconciling the model with human results, confirming that stereoresolution for

  7. [Progressive damage monitoring of corrugated composite skins by the FBG spectral characteristics].

    PubMed

    Zhang, Yong; Wang, Bang-Feng; Lu, Ji-Yun; Gu, Li-Li; Su, Yong-Gang

    2014-03-01

    In the present paper, a method of monitoring progressive damage of composite structures by non-uniform fiber Bragg grating (FBG) reflection spectrum is proposed. Due to the finite element analysis of corrugated composite skins specimens, the failure process under tensile load and corresponding critical failure loads of corrugated composite skin was predicated. Then, the non-uniform reflection spectrum of FBG sensor could be reconstructed and the corresponding relationship between layer failure order sequence of corrugated composite skin and FBG sensor reflection spectrums was acquired. A monitoring system based on FBG non-uniform reflection spectrum, which can be used to monitor progressive damage of corrugated composite skins, was built. The corrugated composite skins were stretched under this FBG non-uniform reflection spectrum monitoring system. The results indicate that real-time spectrums acquired by FBG non-uniform reflection spectrum monitoring system show the same trend with the reconstruction reflection spectrums. The maximum error between the corresponding failure and the predictive value is 8.6%, which proves the feasibility of using FBG sensor to monitor progressive damage of corrugated composite skin. In this method, the real-time changes in the FBG non-uniform reflection spectrum within the scope of failure were acquired through the way of monitoring and predicating, and at the same time, the progressive damage extent and layer failure sequence of corru- gated composite skin was estimated, and without destroying the structure of the specimen, the method is easy and simple to operate. The measurement and transmission section of the system are completely composed of optical fiber, which provides new ideas and experimental reference for the field of dynamic monitoring of smart skin.

  8. EPDM plasticizers

    SciTech Connect

    Godail, M.J.

    1983-08-01

    The properties of paraffinic, naphthenic, and aromatic extender oils used as EPDM plasticizers are discussed in detail. Particular attention is given to viscosity, volatility, specific gravity, and aromatic content.

  9. Plastic Surgery Statistics

    MedlinePlus

    ... PRS GO PSN PSEN GRAFT Contact Us News Plastic Surgery Statistics Plastic surgery procedural statistics from the ... Plastic Surgery Statistics 2005 Plastic Surgery Statistics 2016 Plastic Surgery Statistics Stats Report 2016 National Clearinghouse of ...

  10. Elastic stability of superplastically formed/diffusion-bonded orthogonally corrugated core sandwich plates

    NASA Technical Reports Server (NTRS)

    Ko, W. L.

    1980-01-01

    The paper concerns the elastic buckling behavior of a newly developed superplastically formed/diffusion-bonded (SPF/DB) orthogonally corrugated core sandwich plate. Uniaxial buckling loads were calculated for this type of sandwich plate with simply supported edges by using orthotropic sandwich plate theory. The buckling behavior of this sandwich plate was then compared with that of an SPF/DB unidirectionally corrugated core sandwich plate under conditions of equal structural density. It was found that the buckling load for the former was considerably higher than that of the latter.

  11. Elastic constants for superplastically formed/diffusion-bonded corrugated sandwich core

    NASA Technical Reports Server (NTRS)

    Ko, W. L.

    1980-01-01

    Formulas and associated graphs for evaluating the effective elastic constants for a superplastically formed/diffusion bonded (SPF/DB) corrugated sandwich core, are presented. A comparison of structural stiffnesses of the sandwich core and a honeycomb core under conditions of equal sandwich core density was made. The stiffness in the thickness direction of the optimum SPF/DB corrugated core (that is, triangular truss core) is lower than that of the honeycomb core, and that the former has higher transverse shear stiffness than the latter.

  12. Tests of Large Airfoils in the Propeller Research Tunnel, Including Two with Corrugated Surfaces

    NASA Technical Reports Server (NTRS)

    Wood, Donald H

    1930-01-01

    This report gives the results of the tests of seven 2 by 12 foot airfoils (Clark Y, smooth and corrugated, Gottingen 398, N.A.C.A. M-6, and N.A.C.A. 84). The tests were made in the propeller research tunnel of the National Advisory Committee for Aeronautics at Reynolds numbers up to 2,000,000. The Clark Y airfoil was tested with three degrees of surface smoothness. Corrugating the surface causes a flattening of the lift curve at the burble point and an increase in drag at small flying angles.

  13. Experimental investigation of heat transfer and effectiveness in corrugated plate heat exchangers having different chevron angles

    NASA Astrophysics Data System (ADS)

    Kılıç, Bayram; İpek, Osman

    2017-02-01

    In this study, heat transfer rate and effectiveness of corrugated plate heat exchangers having different chevron angles were investigated experimentally. Chevron angles of plate heat exchangers are β = 30° and β = 60°. For this purpose, experimentally heating system used plate heat exchanger was designed and constructed. Thermodynamic analysis of corrugated plate heat exchangers having different chevron angles were carried out. The heat transfer rate and effectiveness values are calculated. The experimental results are shown that heat transfer rate and effectiveness values for β = 60° is higher than that of the other. Obtained experimental results were graphically presented.

  14. Casimir Force on a Surface with Shallow Nanoscale Corrugations: Geometry and Finite Conductivity Effects

    SciTech Connect

    Bao, Y.; Guerout, R.; Lussange, J.; Lambrecht, A.; Cirelli, R. A.; Klemens, F.; Mansfield, W. M.; Pai, C. S.; Chan, H. B.

    2010-12-17

    We measure the Casimir force between a gold sphere and a silicon plate with nanoscale, rectangular corrugations with a depth comparable to the separation between the surfaces. In the proximity force approximation (PFA), both the top and bottom surfaces of the corrugations contribute to the force, leading to a distance dependence that is distinct from a flat surface. The measured Casimir force is found to deviate from the PFA by up to 10%, in good agreement with calculations based on scattering theory that includes both geometry effects and the optical properties of the material.

  15. Structural efficiency studies of corrugated compression panels with curved caps and beaded webs

    NASA Technical Reports Server (NTRS)

    Davis, R. C.; Mills, C. T.; Prabhakaran, R.; Jackson, L. R.

    1984-01-01

    Curved cross-sectional elements are employed in structural concepts for minimum-mass compression panels. Corrugated panel concepts with curved caps and beaded webs are optimized by using a nonlinear mathematical programming procedure and a rigorous buckling analysis. These panel geometries are shown to have superior structural efficiencies compared with known concepts published in the literature. Fabrication of these efficient corrugation concepts became possible by advances made in the art of superplastically forming of metals. Results of the mass optimization studies of the concepts are presented as structural efficiency charts for axial compression.

  16. Graphene-assisted near-field radiative heat transfer between corrugated polar materials

    SciTech Connect

    Liu, X. L.; Zhang, Z. M.

    2014-06-23

    Graphene has attracted great attention in nanoelectronics, optics, and energy harvesting. Here, the near-field radiative heat transfer between graphene-covered corrugated silica is investigated based on the exact scattering theory. It is found that graphene can improve the radiative heat flux between silica gratings by more than one order of magnitude and alleviate the performance sensitivity to lateral shift. The underlying mechanism is mainly attributed to the improved photon tunneling of modes away from phonon resonances. Besides, coating with graphene leads to nonlocal radiative transfer that breaks Derjaguin's proximity approximation and enables corrugated silica to outperform bulk silica in near-field radiation.

  17. Structural properties of superplastically formed/diffusion-bonded orthogonally corrugated core sandwich plates

    NASA Technical Reports Server (NTRS)

    Ko, W. L.

    1980-01-01

    This paper describes a new superplastically formed/diffusion-bonded (SPF/DB) orthogonally corrugated sandwich structure, and presents formulae and the associated plots for evaluating the effective elastic constants for the core of this new sandwich structure. Comparison of structural properties of this new sandwich structure with the conventional honeycomb core sandwich structure was made under the condition of equal sandwich density. It was found that the SPF/DB orthogonally corrugated sandwich core has higher transverse shear stiffness than the conventional honeycomb sandwich core. However, the former has lower stiffness in the sandwich core thickness direction than the latter.

  18. Determination of the geometric corrugation of graphene on SiC(0001) by grazing incidence fast atom diffraction

    SciTech Connect

    Zugarramurdi, A.; Debiossac, M.; Lunca-Popa, P.; Mayne, A. J.; Borisov, A. G.; Mu, Z.; Roncin, P.; Khemliche, H.; Momeni, A.

    2015-03-09

    We present a grazing incidence fast atom diffraction (GIFAD) study of monolayer graphene on 6H-SiC(0001). This system shows a Moiré-like 13 × 13 superlattice above the reconstructed carbon buffer layer. The averaging property of GIFAD results in electronic and geometric corrugations that are well decoupled; the graphene honeycomb corrugation is only observed with the incident beam parallel to the zigzag direction while the geometric corrugation arising from the superlattice is revealed along the armchair direction. Full-quantum calculations of the diffraction patterns show the very high GIFAD sensitivity to the amplitude of the surface corrugation. The best agreement between the calculated and measured diffraction intensities yields a corrugation height of 0.27 ± 0.03 Å.

  19. Effect of Corrugation and Reinforcement on the Dispersion of SH-wave Propagation in Corrugated Poroelastic Layer Lying over a Fibre-reinforced Half-space

    NASA Astrophysics Data System (ADS)

    Singh, Abhishek Kumar; Das, Amrita; Lakshman, Anirban; Chattopadhyay, Amares

    2016-10-01

    The presence of porosity and reinforcement in a medium is an important factor affecting seismic wave propagation and plays vital role in many geophysical prospects. Also, the presence of salt and ore deposits, mountains, basins, mountain roots, etc. is responsible for the existence of corrugated boundary surfaces of constituent layers. Such facts brought motivation for the present paper which deals with the propagation of SH-wave in a heterogeneous fluid-saturated poroelastic layer with corrugated boundaries lying over an initially stressed fibre-reinforced elastic halfspace. Closed form of dispersion relation has been obtained and is found in well agreement to classical Love wave equation for isotropic case. The effect of corrugation, wave number, undulation, position parameter, horizontal compressive/tensile initial stress and heterogeneity on phase velocity has been analysed through numerical computation and graphical illustration. Moreover, comparative study exploring the effect of presence and absence of reinforcement in half-space on dispersion curve is the major highlight of the current study.

  20. Plastic condoms.

    PubMed

    1968-01-01

    Only simple equipment, simple technology and low initial capital investment are needed in their manufacture. The condoms can be made by people who were previously unskilled or only semi-skilled workers. Plastic condoms differ from those made of latex rubber in that the nature of the plastic film allows unlimited shelf-life. Also, the plastic has a higher degree of lubricity than latex rubber; if there is a demand for extra lubrication in a particular market, this can be provided. Because the plastic is inert, these condoms need not be packaged in hermetically sealed containers. All these attributes make it possible to put these condoms on the distributors' shelves in developing countries competitively with rubber condoms. The shape of the plastic condom is based on that of the lamb caecum, which has long been used as luxury-type condom. The plastic condom is made from plastic film (ethylene ethyl acrilate) of 0.001 inch (0.0254 mm.) thickness. In addition, a rubber ring is provided and sealed into the base of the condom for retention during coitus. The advantage of the plastic condom design and the equipment on which it is made is that production can be carried out either in labour-intensive economy or with varying degrees of mechanization and automation. The uniform, finished condom if made using previously untrained workers. Training of workers can be done in a matter of hours on the two machines which are needed to produce and test the condoms. The plastic film is provided on a double wound roll, and condom blanks are prepared by means of a heat-sealing die on the stamping machine. The rubber rings are united to the condom blanks on an assembly machine, which consists of a mandrel and heat-sealing equipment to seal the rubber ring to the base of the condom. Built into the assembly machine is a simple air-testing apparatus that can detect the smallest pinhole flaw in a condom. The manufacturing process is completed by unravelling the condom from the assembly

  1. Method for producing ultrafine-grained materials using repetitive corrugation and straightening

    DOEpatents

    Zhu, Yuntian T.; Lowe, Terry C.; Jiang, Honggang; Huang, Jianyu

    2001-01-01

    A method of refining the grain structure and improving the hardness and strength properties of a metal or metal alloy workpiece is disclosed. The workpiece is subjected to forces that corrugate and then straighten the workpiece. These steps are repeated until an ultrafine-grained product having improved hardness and strength is produced.

  2. A Simple Experiment to Explore Standing Waves in a Flexible Corrugated Sound Tube

    ERIC Educational Resources Information Center

    Amorim, Maria Eva; Sousa, Teresa Delmira; Carvalho, P. Simeao; Sousa, Adriano Sampaioe

    2011-01-01

    Sound tubes, pipes, and singing rods are used as musical instruments and as toys to perform amusing experiments. In particular, corrugated tubes present unique characteristics with respect to the sounds they can produce; that is why they have been studied so intensively, both at theoretical and experimental levels. Experimental studies usually…

  3. Psychometric properties of startle and corrugator response in NPU, Affective Picture Viewing, and Resting State tasks

    PubMed Central

    Kaye, Jesse T.; Bradford, Daniel E.; Curtin, John J.

    2016-01-01

    The current study provides a comprehensive evaluation of critical psychometric properties of commonly used psychophysiology laboratory tasks/measures within the NIMH RDoC. Participants (N = 128) completed the No Shock, Predictable Shock, Unpredictable Shock (NPU) task, Affective Picture Viewing task, and Resting State task at two study visits separated by one week. We examined potentiation/modulation scores in NPU (predictable or unpredictable shock vs. no shock) and Affective Picture Viewing tasks (pleasant or unpleasant vs. neutral pictures) for startle and corrugator responses with two commonly used quantification methods. We quantified startle potentiation/modulation scores with raw and standardized responses. We quantified corrugator potentiation/modulation in the time and frequency domains. We quantified general startle reactivity in the Resting State Task as the mean raw startle response during the task. For these three tasks, two measures, and two quantification methods we evaluated effect size robustness and stability, internal consistency (i.e., split-half reliability), and one-week temporal stability. The psychometric properties of startle potentiation in the NPU task were good but concerns were noted for corrugator potentiation in this task. Some concerns also were noted for the psychometric properties of both startle and corrugator modulation in the Affective Picture Viewing task, in particular for pleasant picture modulation. Psychometric properties of general startle reactivity in the Resting State task were good. Some salient differences in the psychometric properties of the NPU and Affective Picture Viewing tasks were observed within and across quantification methods. PMID:27167717

  4. Moisture diffusion through a corrugated fiberboard under compressive loading : its deformation and stiffness response

    Treesearch

    Adeeb A. Rahman; Thomas J. Urbanik; Mustafa Mahamid

    2002-01-01

    This research develops a model using finite element to study the response of a panel made of a typical commercial corrugated fireboard due to an induced moisture function at one side of the fiberboard. The model predicts how the moisture diffusion will permeate through the fiberboard's layers (medium and liners) providing information on moisture content at any...

  5. Corrugated velocity patterns in the spiral galaxies NGC 278, NGC 1058, NGC 2500 & UGC 3574

    NASA Astrophysics Data System (ADS)

    Sánchez Gil, M. C.; Alfaro, E. J.; Pérez, E.

    2013-05-01

    In this work we address the study of the detection in Ha of a radial corrugation in the vertical velocity field in a sample of four nearly face-on, spiral galaxies. The geometry of the problem is a main criterion in the selection of the sample as well as of the azimuthal angle of the slits. These spatial corrugations must be equally associated with wavy vertical motions in the galactic plane with a strong large-scale consistency. Evidence of these kinematic waves were first detected in the analysis of the rotation curves of spiral galaxies (e.g. te{1963ApJ...137..363D,1965BOTT....4....8P}), but it was not until 2001 that te{2001ApJ...550..253A} analyzed in more detail the velocity corrugations in NGC 5427 and a possible physical mechanism for their origin. The aim of this study is to analyze the corrugated velocity pattern in terms of the star formation processes. We describe the geometry of the problem and establish its fundamental relationships.

  6. A Simple Experiment to Explore Standing Waves in a Flexible Corrugated Sound Tube

    ERIC Educational Resources Information Center

    Amorim, Maria Eva; Sousa, Teresa Delmira; Carvalho, P. Simeao; Sousa, Adriano Sampaioe

    2011-01-01

    Sound tubes, pipes, and singing rods are used as musical instruments and as toys to perform amusing experiments. In particular, corrugated tubes present unique characteristics with respect to the sounds they can produce; that is why they have been studied so intensively, both at theoretical and experimental levels. Experimental studies usually…

  7. Shear band blocking in explosively driven collapse of corrugated Ni-Al laminate cylinder

    NASA Astrophysics Data System (ADS)

    Olney, Karl; Chiu, Po-Hsun; Higgins, Andrew; Serge, Matthew; Fritz, Gregory; Stover, Adam; Nesterenko, Vitali; Benson, David

    2013-03-01

    Ni-Al laminate materials have been identified as a possible material system that can be used as a reactive material due to the self-sustaining reaction between Al and Ni layers. Besides traditional ignition methods, shear bands developed during mechanical loading can provide sites where ignition can occur. Corrugated Ni-Al laminate samples were created by swaging alternating layers of Ni (20 micrometers thick) and Al (30 micrometers thick) foils. The thick-walled cylinder (TWC) technique was performed on a corrugated Ni-Al laminate cylinder sample to examine shear band development in this material. Post experiment examination of the corrugated Ni-Al laminate material showed that the development of global shear bands were blocked via mesoscale mechanisms. The collapse of the corrugated laminate cylinder was simulated providing insight into these mesoscale mechanisms that were involved in blocking the development of shear bands during the experiment. Despite the shear band resistance of the material, several regions of the sample had localized reactions of Al and Ni spanning approximately 10-20 layers of laminate. Funding was provided by ONR MURI N00014-07-1-0740 (Program Officer Dr. Clifford Bedford)

  8. Binderless fiberboard : comparison of fiber from recycled corrugated containers and refined small-diameter whole treetops

    Treesearch

    John F. Hunt; Karen Supan

    2006-01-01

    Whereas many research activities focus on developing value-added processes that use forest residues, scientists must also investigate the mechanical properties of products made from recycled fiber resources. This study compared the tensile and bending properties of binderless panels made from recycled corrugated containers with properties of panels made from lodgepole...

  9. Pressure and heating-rate distributions on a corrugated surface in a supersonic turbulent boundary layer

    NASA Technical Reports Server (NTRS)

    Sawyer, J. W.

    1977-01-01

    Drag and heating rates on wavy surfaces typical of current corrugated plate designs for thermal protection systems were determined experimentally. Pressure-distribution, heating-rate, and oil-flow tests were conducted in the Langley Unitary Plan wind tunnel at Mach numbers of 2.4 and 4.5 with the corrugated surface exposed to both thick and thin turbulent boundary layers. Tests were conducted with the corrugations at cross-flow angles from 0 deg to 90 deg to the flow. Results show that for cross-flow angles of 30 deg or less, the pressure drag coefficients are less than the local flat-plate skin-friction coefficients and are not significantly affected by Mach number, Reynolds number, or boundary-layer thickness over the ranges investigated. For cross-flow angles greater than 30 deg, the drag coefficients increase significantly with cross-flow angle and moderately with Reynolds number. Increasing the Mach number causes a significant reduction in the pressure drag. The average and peak heating penalties due to the corrugated surface are small for cross-flow angles of 10 deg or less but are significantly higher for the larger cross-flow angles.

  10. Wakefield computations for a corrugated pipe as a beam dechirper for FEL applications

    SciTech Connect

    Ng, C. K.; Bane, K. L.F.

    2015-06-09

    A beam “dechirper” based on a corrugated, metallic vacuum chamber has been proposed recently to cancel residual energy chirp in a beam before it enters the undulator in a linac-based X-ray FEL. Rather than the round geometry that was originally proposed, we consider a pipe composed of two parallel plates with corrugations. The advantage is that the strength of the wake effect can be tuned by adjusting the separation of the plates. The separation of the plates is on the order of millimeters, and the corrugations are fractions of a millimeter in size. The dechirper needs to be meters long in order to provide sufficient longitudinal wakefield to cancel the beam chirp. Considerable computation resources are required to determine accurately the wakefield for such a long structure with small corrugation gaps. Combining the moving window technique and parallel computing using multiple processors, the time domain module in the parallel finite-element electromagnetic suite ACE3P allows efficient determination of the wakefield through convergence studies. In this paper, we will calculate the longitudinal, dipole and quadrupole wakefields for the dechirper and compare the results with those of analytical and field matching approaches.

  11. Response of corrugated fiberboard to moisture flow : a 3-D finite element transient nonlinear analysis

    Treesearch

    Adeeb A. Rahman; Thomas J. Urbanik; Mustafa Mahamid

    2003-01-01

    Collapse of fiberboard packaging boxes, in the shipping industry, due to rise in humidity conditions is common and very costly. A 3D FE nonlinear model is developed to predict the moisture flow throughout a corrugated packaging fiberboard sandwich structure. The model predicts how the moisture diffusion will permeate through the layers of a fiberboard (medium and...

  12. Comparison of postbuckling model and finite element model with compression strength of corrugated boxes

    Treesearch

    Thomas J. Urbanik; Edmond P. Saliklis

    2002-01-01

    Conventional compression strength formulas for corrugated fiberboard boxes are limited to geometry and material that produce an elastic postbuckling failure. Inelastic postbuckling can occur in squatty boxes and trays, but a mechanistic rationale for unifying observed strength data is lacking. This study employs a finite element model, instead of actual experiments, to...

  13. New rapid method for determining edgewise compressive strength of corrugated fiberboard

    Treesearch

    John W. Koning

    1986-01-01

    The objective of this study was to determine if corrugated fiberboard specimens that had been necked down with a common router would yield acceptable edgewise compressive strength values. Tests were conducted on specimens prepared using a circular saw and router, and the results were compared with those obtained on specimens prepared according to TAPPI Test Method T...

  14. Combined electromagnetohydrodynamic flow in a microparallel channel with slightly corrugated walls

    NASA Astrophysics Data System (ADS)

    Buren, Mandula; Jian, Yongjun; Chang, Long; Li, Fengqin; Liu, Quansheng

    2017-04-01

    In this work a perturbation method is introduced to study the effect of wall roughness on the combined electromagnetohydrodynamic flow in a microparallel channel with slightly corrugated walls under the Debye–Hückel approximation. The driving force is the sum of the electro-osmotic and Lorentz forces. The wall corrugations are described by periodic sinusoidal waves with small amplitudes compared to the channel height. The perturbation solutions of velocity and electric potential are obtained. The results show that the velocity and potential distributions are significantly disturbed by the wall roughness. The mean velocity can be enhanced at long-wavelength corrugations when the phase difference between the wall corrugations is near π. The enhancement of the mean velocity increases with S which represents the strength of the electric field in the x-direction. The decreasing effect of wall roughness increases with the wavenumber and decreases with the phase difference and the normalized reciprocal thickness of the electric double layer. The phase difference of wall roughness becomes unimportant when the wavenumber or Hartmann number is larger than 3.

  15. Conductor load bearing roller for a gas-insulated transmission line having a corrugated outer conductor

    SciTech Connect

    Fischer, William H.; Yoon, Kue H.

    1984-04-10

    A gas-insulated transmission line includes a corrugated outer conductor, an inner conductor disposed within and insulated from the outer conductor by means of support insulators and an insulating gas, and a transport device for supporting and permitting movement of the inner conductor/insulating support assembly axially along the corrugated outer conductor without radial displacement. The transport device includes two movable contacts, such as skids or rollers, supported on a common pivot lever, the pivot lever being rotatably disposed about a pivot lever axis, which pivot lever axis is in turn disposed on the periphery of a support insulator or particle trap if one is used. The movable contacts are separated axially a distance equal to the axial distance between the peaks and valleys of the corrugations of the outer conductor and separated radially a distance equal to the radial distance between the peaks and valleys of the corrugations of the outer conductor. The transport device has the pivot lever axis disposed perpendicular to the direction of travel of the inner conductor/insulating support assembly.

  16. Stress State of Longitudinally Corrugated Hollow Cylinders with Different Cross-Sectional Curvature

    NASA Astrophysics Data System (ADS)

    Grigorenko, Ya. M.; Rozhok, L. S.

    2016-11-01

    The effect of the change in the curvature due to changes in the epicycle radius on the stress state of longitudinally corrugated hollow cylinders is studied using a spatial problem statement, the variable separation method, discrete Fourier series, and the discrete-orthogonalization method. The results presented in the form of graphs of distribution of displacements and stresses are analyzed

  17. Plastic Bronchitis.

    PubMed

    Rubin, Bruce K

    2016-09-01

    Plastic bronchitis is an uncommon and probably underrecognized disorder, diagnosed by the expectoration or bronchoscopic removal of firm, cohesive, branching casts. It should not be confused with purulent mucous plugging of the airway as seen in patients with cystic fibrosis or bronchiectasis. Few medications have been shown to be effective and some are now recognized as potentially harmful. Current research directions in plastic bronchitis research include understanding the genetics of lymphatic development and maldevelopment, determining how abnormal lymphatic malformations contribute to cast formation, and developing new treatments.

  18. Time-frequency characterization of rail corrugation under a combined auto-regressive and matched filter scheme

    NASA Astrophysics Data System (ADS)

    Hory, C.; Bouillaut, L.; Aknin, P.

    2012-05-01

    Rail corrugation is an oscillatory mechanical wear of rail surface raising from the long-term interaction between rail and wheel. Signal processing approaches to corrugation monitoring, as recommended by the European standards for instance, are designed either in the mileage domain or in the wavelength domain. However a joint mileage and wavelength domain analysis of the monitoring data can provide crucial information about the simultaneous amplitude and wavelength modulations of the corrugation modes. It is proposed in this paper to perform such a mileage-wavelength domain analysis of rail corrugation using the class of Auto-Regressive-MAtched Filterbank (AR-MAFI) methods. We show that these methods assume a statistical model that fits the corrugation data. We discuss also the optimal parameter settings for the analysis of corrugation data. Experimental studies performed on data collected from the French RATP metro network show that the AR-MAFI methods outperform (in terms of readability and accuracy) the standard distance domain or wavelength domain methods in localizing and characterizing corrugation.

  19. Plastics Technician.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document contains 16 units to consider for use in a tech prep competency profile for the occupation of plastics technician. All the units listed will not necessarily apply to every situation or tech prep consortium, nor will all the competencies within each unit be appropriate. Several units appear within each specific occupation and would…

  20. Plastics Technician.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document contains 16 units to consider for use in a tech prep competency profile for the occupation of plastics technician. All the units listed will not necessarily apply to every situation or tech prep consortium, nor will all the competencies within each unit be appropriate. Several units appear within each specific occupation and would…

  1. Research on a 170 GHz, 2 MW coaxial cavity gyrotron with inner-outer corrugation

    SciTech Connect

    Hou, Shenyong; Yu, Sheng; Li, Hongfu

    2015-03-15

    In this paper, a coaxial cavity gyrotron with inner-outer corrugation is researched. The electron kineto-equations and the first order transmission line equations of the gyrotron are derived from Lorentz force equation and the transmission line theory, respectively. And then, a 2 MW, 170 GHz coaxial cavity gyrotron with inner-outer corrugation is designed. By means of numerical calculation, the beam-wave interaction of the coaxial cavity gyrotron with inner-outer corrugation is investigated. Results show that the efficient and the outpower of the gyrotron are 42.3% and 2.38 MW, respectively.

  2. GLASS FIBER REINFORCED PLASTICS,

    DTIC Science & Technology

    Contents: Fibrous glass fillers Binders used in the glass plastic industry Method of manufacturing glass plastics and glass plastic articles Properties of fiberglass Primary areas for use of glass fibre reinforced plastics

  3. Plastic bronchitis

    PubMed Central

    Singhi, Anil Kumar; Vinoth, Bharathi; Kuruvilla, Sarah; Sivakumar, Kothandam

    2015-01-01

    Plastic bronchitis, a rare but serious clinical condition, commonly seen after Fontan surgeries in children, may be a manifestation of suboptimal adaptation to the cavopulmonary circulation with unfavorable hemodynamics. They are ominous with poor prognosis. Sometimes, infection or airway reactivity may provoke cast bronchitis as a two-step insult on a vulnerable vascular bed. In such instances, aggressive management leads to longer survival. This report of cast bronchitis discusses its current understanding. PMID:26556975

  4. Analysis of a disk-on-rod surface wave element inside a corrugated horn using the mode-matching technique

    NASA Technical Reports Server (NTRS)

    Chen, J. C.

    1995-01-01

    A disk-on-rod inside a corrugated horn is one of the horn configurations for dual-frequency or wide-band operation. A mode-matching analysis method is described. A disk-on-rod inside a corrugated horn is represented as a series of coaxial waveguide sections and circular waveguide sections connected to each other. Three kinds of junctions need to be considered: coaxial-to-coaxial, coaxial-to-circular, and circular-to-circular. A computer program was developed to calculate the scattering matrix and the radiation pattern of a disk-on-rod inside a corrugated horn. The software as verified by experiment, and good agreement between calculation and measurement was obtained. The disk-on-rod inside a corrugated horn design gives an option to the Deep Space Network dual-frequency operation system, which currently is a two-horn/one-dichroic plate system.

  5. Particle trap to sheath contact for a gas-insulated transmission line having a corrugated outer conductor

    DOEpatents

    Fischer, William H.; Cookson, Alan H.; Yoon, Kue H.

    1984-04-10

    A particle trap to outer elongated conductor or sheath contact for gas-insulated transmission lines. The particle trap to outer sheath contact of the invention is applicable to gas-insulated transmission lines having either corrugated or non-corrugated outer sheaths. The contact of the invention includes an electrical contact disposed on a lever arm which in turn is rotatably disposed on the particle trap and biased in a direction to maintain contact between the electrical contact and the outer sheath.

  6. Extremely long range surface polaritons in a thin corrugated metal film

    NASA Astrophysics Data System (ADS)

    Korovin, Alexander V.

    2012-11-01

    The essential increase of propagation length of a long range surface plasmon polariton in a thin symmetrically corrugated plasmon-carrying film embedded in a dielectric medium is theoretically predicted. The calculations are based on the differential formalism for the system of Maxwells equations where the solution for electromagnetic fields is written as a superposition of partial plane waves in the presentation of a curvilinear non-orthogonal coordinates system for simplifying the boundary conditions. The spectral and angular dependencies of p-polarized light transmittance/reflectance demonstrate that the in-plane shift between both profiles of corrugated film drastically changes the surface plasmon polariton propagation length from minimum of the asymmetric profile to maximum of the symmetric one. The obtained results were qualitatively explained using the model of weakly coupled photonic wells.

  7. Two-phase flow patterns in adiabatic and diabatic corrugated plate gaps

    NASA Astrophysics Data System (ADS)

    Polzin, A.-E.; Kabelac, S.; de Vries, B.

    2016-09-01

    Correlations for two-phase heat transfer and pressure drop can be improved considerably, when they are adapted to specific flow patterns. As plate heat exchangers find increasing application as evaporators and condensers, there is a need for flow pattern maps for corrugated plate gaps. This contribution presents experimental results on flow pattern investigations for such a plate heat exchanger background, using an adiabatic visualisation setup as well as a diabatic setup. Three characteristic flow patterns were observed in the considered range of two-phase flow: bubbly flow, film flow and slug flow. The occurrence of these flow patterns is a function of mass flux, void fraction, fluid properties and plate geometry. Two different plate geometries having a corrugation angle of 27° and 63°, respectively and two different fluids (water/air and R365mfc liquid/vapor) have been analysed. A flow pattern map using the momentum flux is presented.

  8. Vibroacoustic Characterization of Corrugated-Core and Honeycomb-Core Sandwich Panels

    NASA Technical Reports Server (NTRS)

    Allen, Albert; Schiller, Noah

    2016-01-01

    The vibroacoustic characteristics of two candidate launch vehicle fairing structures, corrugated- core and honeycomb-core sandwich designs, were studied. The study of these structures has been motivated by recent risk reduction efforts focused on mitigating high noise levels within the payload bays of large launch vehicles during launch. The corrugated-core sandwich concept is of particular interest as a dual purpose structure due to its ability to harbor resonant noise control systems without appreciably adding mass or taking up additional volume. Specifically, modal information, wavelength dispersion, and damping were determined from a series of vibrometer measurements and subsequent analysis procedures carried out on two test panels. Numerical and analytical modeling techniques were also used to assess assumed material properties and to further illuminate underlying structural dynamic aspects. Results from the tests and analyses described herein may serve as a reference for additional vibroacoustic studies involving these or similar structures.

  9. Enhanced response and sensitivity of self-corrugated graphene sensors with anisotropic charge distribution

    NASA Astrophysics Data System (ADS)

    Yol Jeong, Seung; Jeong, Sooyeon; Won Lee, Sang; Tae Kim, Sung; Kim, Daeho; Jin Jeong, Hee; Tark Han, Joong; Baeg, Kang-Jun; Yang, Sunhye; Seok Jeong, Mun; Lee, Geon-Woong

    2015-06-01

    We introduce a high-performance molecular sensor using self-corrugated chemically modified graphene as a three dimensional (3D) structure that indicates anisotropic charge distribution. This is capable of room-temperature operation, and, in particular, exhibiting high sensitivity and reversible fast response with equilibrium region. The morphology consists of periodic, “cratered” arrays that can be formed by condensation and evaporation of graphene oxide (GO) solution on interdigitated electrodes. Subsequent hydrazine reduction, the corrugated edge area of the graphene layers have a high electric potential compared with flat graphene films. This local accumulation of electrons interacts with a large number of gas molecules. The sensitivity of 3D-graphene sensors significantly increases in the atmosphere of NO2 gas. The intriguing structures have several advantages for straightforward fabrication on patterned substrates, high-performance graphene sensors without post-annealing process.

  10. Comparative Analysis of Buckling Load of Circular and Corrugated Tubes by Utilizing Key Performance Indicators

    NASA Astrophysics Data System (ADS)

    Ur Rahim, Mohammad Reyaz; Akhtar, S.; Bharti, P. K.

    2017-08-01

    The performance of buckling load of tubular structures under quasi-static axial loading is quite appreciable, numerous tubes of various cross-section have been extensively investigated and corrugated sections have been designed to further improve the performance. In this paper, a carefully designed set of key performance indicators (KPIs) is utilized to assess and compare the buckling load of circular and corrugated tubes. A series of diagrams related to KPIs with various parameters of tubes are presented to demonstrate the influence of sectional configuration on the performance of tubes as well as the effect of the material on the potential of the same. The work is inestimable to engineering designs and applications, and further studies on the buckling load of other configurations.

  11. Focused ion beam lithography for fabrication of suspended nanostructures on highly corrugated surfaces.

    PubMed

    Erdmanis, M; Sievilä, P; Shah, A; Chekurov, N; Ovchinnikov, V; Tittonen, I

    2014-08-22

    We propose a nanofabrication method that allows for patterning on extremely corrugated surfaces with micrometer-size features. The technique employs focused ion beam nanopatterning of ion-sensitive inorganic resists formed by atomic layer deposition at low temperature. The nanoscale resolution on corrugated surfaces is ensured by inherently large depth of focus of a focused ion beam system and very uniform resist coating. The utilized TiO₂ and Al₂O₃ resists show high selectivity in deep reactive ion etching and enable the release of suspended nanostructures by dry etching. We demonstrate the great flexibility of the process by fabricating suspended nanostructures on flat surfaces, inclined walls, and on the bottom of deep grooves.

  12. SELF-TRAPPING OF DISKOSEISMIC CORRUGATION MODES IN NEUTRON STAR SPACETIMES

    SciTech Connect

    Tsang, David; Pappas, George

    2016-02-10

    We examine the effects of higher-order multipole contributions of rotating neutron star (NS) spacetimes on the propagation of corrugation (c-)modes within a thin accretion disk. We find that the Lense–Thirring precession frequency, which determines the propagation region of the low-frequency fundamental corrugation modes, can experience a turnover allowing for c-modes to become self-trapped for sufficiently high dimensionless spin j and quadrupole rotational deformability α. If such self-trapping c-modes can be detected, e.g., through phase-resolved spectroscopy of the iron line for a high-spin low-mass accreting neutron star, this could potentially constrain the spin-induced NS quadrupole and the NS equation of state.

  13. Simulation and analysis on ultrasonic testing for the cement grouting defects of the corrugated pipe

    SciTech Connect

    Qingbang, Han; Ling, Chen; Changping, Zhu

    2014-02-18

    The defects exist in the cement grouting process of prestressed corrugated pipe may directly impair the bridge safety. In this paper, sound fields propagation in concrete structures with corrugated pipes and the influence of various different defects are simulated and analyzed using finite element method. The simulation results demonstrate a much complex propagation characteristic due to multiple reflection, refraction and scattering, where the scattering signals caused by metal are very strong, while the signals scattered by an air bubble are weaker. The influence of defect both in time and frequency domain are found through deconvolution treatment. In the time domain, the deconvolution signals correspond to larger defect display a larger head wave amplitude and shorter arrive time than those of smaller defects; in the frequency domain, larger defect also shows a stronger amplitude, lower center frequency and lower cutoff frequency.

  14. Corrugated structure insertion for extending the SASE bandwidth up to 3% at the European XFEL

    NASA Astrophysics Data System (ADS)

    Zagorodnov, I.; Feng, G.; Limberg, T.

    2016-11-01

    The usage of x-ray free electron laser (XFEL) in femtosecond nanocrystallography involves sequential illumination of many small crystals of arbitrary orientation. Hence a wide radiation bandwidth will be useful in order to obtain and to index a larger number of Bragg peaks used for determination of the crystal orientation. Considering the baseline configuration of the European XFEL in Hamburg, and based on beam dynamics simulations, we demonstrate here that the usage of corrugated structures allows for a considerable increase in radiation bandwidth. Data collection with a 3% bandwidth, a few microjoule radiation pulse energy, a few femtosecond pulse duration, and a photon energy of 5.4 keV is possible. For this study we have developed an analytical modal representation of the short-range wake function of the flat corrugated structures for arbitrary offsets of the source and the witness particles.

  15. Simulation and analysis on ultrasonic testing for the cement grouting defects of the corrugated pipe

    NASA Astrophysics Data System (ADS)

    Qingbang, Han; Ling, Chen; Changping, Zhu

    2014-02-01

    The defects exist in the cement grouting process of prestressed corrugated pipe may directly impair the bridge safety. In this paper, sound fields propagation in concrete structures with corrugated pipes and the influence of various different defects are simulated and analyzed using finite element method. The simulation results demonstrate a much complex propagation characteristic due to multiple reflection, refraction and scattering, where the scattering signals caused by metal are very strong, while the signals scattered by an air bubble are weaker. The influence of defect both in time and frequency domain are found through deconvolution treatment. In the time domain, the deconvolution signals correspond to larger defect display a larger head wave amplitude and shorter arrive time than those of smaller defects; in the frequency domain, larger defect also shows a stronger amplitude, lower center frequency and lower cutoff frequency.

  16. Enhanced response and sensitivity of self-corrugated graphene sensors with anisotropic charge distribution

    PubMed Central

    Yol Jeong, Seung; Jeong, Sooyeon; Won Lee, Sang; Tae Kim, Sung; Kim, Daeho; Jin Jeong, Hee; Tark Han, Joong; Baeg, Kang-Jun; Yang, Sunhye; Seok Jeong, Mun; Lee, Geon-Woong

    2015-01-01

    We introduce a high-performance molecular sensor using self-corrugated chemically modified graphene as a three dimensional (3D) structure that indicates anisotropic charge distribution. This is capable of room-temperature operation, and, in particular, exhibiting high sensitivity and reversible fast response with equilibrium region. The morphology consists of periodic, “cratered” arrays that can be formed by condensation and evaporation of graphene oxide (GO) solution on interdigitated electrodes. Subsequent hydrazine reduction, the corrugated edge area of the graphene layers have a high electric potential compared with flat graphene films. This local accumulation of electrons interacts with a large number of gas molecules. The sensitivity of 3D-graphene sensors significantly increases in the atmosphere of NO2 gas. The intriguing structures have several advantages for straightforward fabrication on patterned substrates, high-performance graphene sensors without post-annealing process. PMID:26053892

  17. Use of a corrugated surface to enhance radiation tolerance in a GaAs solar cell

    NASA Technical Reports Server (NTRS)

    Leon, Rosa P.; Piszczor, Michael F., Jr.

    1985-01-01

    The use of a corrugated surface on a GaAs solar cell and its effects on radiation resistance were studied. A compute code was developed to determine the performance of the cell for various geometric parameters. The large optical absorption coefficient of GaAs allows grooves to be only 4-5 micrometers deep. Using accepted material parameters for GaAs solar cells the theoretical performances were compared for various corrugated cells before and after minority carrier diffusion length degradation. The total power output was maximized for both n(+)/p and p(+)/n cells. Optimum values of 1.0-1.5 and 5.0 micrometers for groove and ridge widths respectively were determined.

  18. Turbulent heat transfer in corrugated-wall channels with and without fins

    NASA Technical Reports Server (NTRS)

    Amano, R. S.; Bagherlee, A.; Smith, R. J.; Niess, T. G.

    1987-01-01

    A numerical study is performed examining flow and heat transfer characteristics in a channel with periodically corrugated walls. The complexity of the flow in this type of channel is demonstrated by such phenomena as flow impingement on the walls, separation at the bend corners, flow reattachment, and flow recirculation. Because of the strong nonisotropic nature of the turbulent flow in the channel, the full Reynolds-stress model was employed for the evaluation of turbulence quantities. Computations are made for several different corrugation periods and for different Reynolds numbers. The results computed by using the present model show excellent agreement with experimental data for mean velocities, the Reynolds stresses, and average Nusselt numbers. The study was further extended to a channel flow where fins are inserted at bends in the channel. It was observed that the insertion of fins in the flow passage has a visible effect on flow patterns and skin friction along the channel wall.

  19. Buckling test of a 3-meter-diameter corrugated graphite-epoxy ring-stiffened cylinder

    NASA Technical Reports Server (NTRS)

    Davis, R. C.

    1982-01-01

    A three m diameter by three m long corrugated cylindrical shell with external stiffening rings was tested to failure by buckling. The corrugation geometry for the graphite epoxy composite cylinder wall was optimized to withstand a compressive load producing an ultimate load intensity of 157.6 kN/m without buckling. The test method used to produce the design load intensity was to mount the specimen as a cantilevered cylinder and apply a pure bending moment to the end. A load introduction problem with the specimen was solved by using the BOSOR 4 shell of revolution computer code to analyze the shell and attached loading fixtures. The cylinder test loading achieved was 101 percent of design ultimate, and the resulting mass per unit of shell wall area was 1.96 kg/sq m.

  20. Low-frequency metamaterial absorber with small-size unit cell based on corrugated surface

    NASA Astrophysics Data System (ADS)

    Wang, Nan; Dong, Xiaochun; Zhou, Weicheng; He, Chuanwang; Jiang, Wei; Hu, Song

    2016-02-01

    In this paper, we report the design, analysis, and simulation of the low-frequency perfect metamaterial absorber (MMA) based on corrugated surface, which has very small unit-cell size. The proposed MMA consist of a regular square-array and a metallic background plane, separated by a corrugated surface with periodic square-pillar-array. Through the optimized design, the ratios between lattice constant and resonance wavelength for nearly-perfect and high absorption MMA are close to 1/15 and 1/21, respectively. To explain the absorption mechanism of suggested structures, the surface current and electromagnetic field distributions are given. Moreover, the absorption peaks remain high with large angles of incidence for both transverse electric and transverse magnetic polarizations, which provide more efficient absorptions for oblique incident electromagnetic wave.

  1. Flow noise in a corrugated pipe in terms of the theory of instability waves

    NASA Astrophysics Data System (ADS)

    Kopiev, V. F.; Mironov, M. A.; Yakovets, M. A.

    2015-09-01

    An air flow through a pipe with a corrugated inner surface is accompanied by the generation of a tone (multitone), i.e., coherent, acoustic signal. The main processes giving rise to such a generation include the forced excitation of the active medium in the resonator (the pipe) and the feedback, which leads to nonlinear amplification of one or several resonator harmonics because of the nonlinear competition of waves. The medium in the pipe becomes active owing to the processes that accompany the air flow about the corrugated wall. The purpose of the present study is to provide qualitative explanations based on a simple example for the possibility of multitone sound generation, as well as for the known experimental data.

  2. The Influence of Railpad Stiffness on Wheelset/track Interaction and Corrugation Growth

    NASA Astrophysics Data System (ADS)

    ILIAS, H.

    1999-11-01

    The aim of the paper is to investigate the influence of the railpad stiffness on vehicle/track interaction and corrugation growth. For the structural dynamics of vehicle and track a time domain model is used which includes all relevant contact non-linearities. A simple war model enables profile development calculations to be undertaken in the time domain by closing the feedback loop between a short-term dynamical process (structural dynamics) and a long-term damaging process (wear). The initial profile is taken from measurements of a ground rail. It is found that stiffer railpads lead to higher corrugation growth. The parametric excitation from passing sleepers is found to be important. For the chosen operational values this wavelength-fixing mechanism dominates the so-called final profiles of profile development calculations.

  3. Spoof localized surface plasmons in corrugated ring structures excited by microstrip line.

    PubMed

    Yang, Bao Jia; Zhou, Yong Jin; Xiao, Qian Xun

    2015-08-10

    We have investigated the fundamental and high-order spoof localized surface plasmons (LSPs) modes in the proposed corrugated ring resonator printed on a thin dielectric substrate with or without ground plane. An efficient and ease-of-integration method to excite spoof LSPs in the textured ring resonator has been adopted to suppress unwanted high-order modes and enhance fundamental modes. A multi-band-pass filter has been proposed and numerically demonstrated. Experimental results at the microwave frequencies verify the high performances of the corrugated ring resonator and the filter, showing great agreements with the simulation results. We have also shown that the fabricated device is sensitive to the variation of the refraction index of materials under test, even when the material is as thin as paper.

  4. Wavelength filtering and demultiplexing devices based on ultrathin corrugated MIM waveguides

    NASA Astrophysics Data System (ADS)

    Yang, Bao Jia; Zhou, Yong Jin

    2016-05-01

    We have numerically investigated the transmission properties of spoof surface plasmon polaritons on the ultrathin corrugated metal-insulator-metal (MIM) waveguides with different grooves. A band-pass plasmonic filter with T-shaped grooves and a compact 4-way wavelength division demultiplexing (WDM) incorporating the filter have been proposed. The whole 4-way WDM is more compact by the use of corrugated MIM waveguides with meander grooves. The near electric field distributions show that electromagnetic waves at different frequencies are guided and propagate along different branches with good isolation between branches. The experimental and numerical results have shown good agreements and validated the functions of the 4-way wavelength splitter. We also numerically investigate the 4-way WDM at terahertz frequencies by scaling down the whole structure. It is believed that the spoof plasmonic devices can find more applications in the plasmonic integration platform, such as optical communications, signal processing and spectral engineering.

  5. The scattering of obliquely incident plane waves from a corrugated conducting surface

    NASA Technical Reports Server (NTRS)

    Le Vine, D. M.

    1976-01-01

    A physical optics solution is presented for the scattering of plane waves from a perfectly conducting corrugated surface in the case of waves incident from an arbitrary direction and for an observer far from the surface. This solution is used to compute the radar cross section of the surface in the case of backscatter from irregular (i.e., stochastic) corrugations. An interesting feature of the solution is the occurrence of singularities in the scattered fields. These singularities appear to be a manifestation of focusing by the surface at its 'stationary' points. Whether or not the singularities occur in the solution depends on the manner in which one restricts the analysis to the far-field.

  6. Investigation on Periodically Surface-Corrugated Long-Period Gratings Inscribed on Photonic Crystal Fibers.

    PubMed

    Han, Young-Geun

    2017-12-01

    Transmission characteristics of periodically surface-corrugated long-period gratings (LPGs) inscribed on photonic crystal fibers (PCFs) using a wet-etching technique were experimentally investigated. A conventional wet method was implemented to periodically engrave the silica cladding region of the PCFs resulting in the periodic surface corrugation in the PCF. After applying the external strain to the PCF with the periodic surface micro-ridges, periodic modulation of refractive index based on the photoelastic effect is induced resulting in the formation of the PCF-based LPG. Increasing the applied strain successfully improves the extinction ratio of the resonant peak of the PCF-based LPG without the resonant wavelength shift. We also measured the transmission characteristics of the PCF-based LPG with variations in temperature and ambient index.

  7. Multiple channels for horizontal, but only one for vertical corrugations? A new look at the stereo anisotropy.

    PubMed

    Serrano-Pedraza, Ignacio; Read, Jenny C A

    2010-10-01

    Stereo vision displays a well-known anisotropy: disparity-defined slant is easier to detect for rotations about a horizontal axis than about a vertical axis, and low-frequency sinusoidal depth corrugations are easier to detect when the corrugations are horizontal than when they are vertical. Here, we determined disparity thresholds for vertically and horizontally oriented depth corrugations with both sinusoidal and square-wave profiles. We found that the orientation anisotropy for square waves is much weaker than for sine waves and is almost independent of frequency. This weaker anisotropy for square waves can be explained by considering the Fourier harmonics present in the stimulus. Using linear models imported from the luminance and texture perception domain, the disparity thresholds for square waves can be very well predicted from those for sine waves, for both horizontally and vertically oriented corrugations. For horizontally oriented corrugations, models based on the root mean square of the output of a single linear channel or the output of multiple linear channels worked equally well. This is consistent with previous evidence suggesting that stereo vision has multiple channels tuned to different spatial frequencies of horizontally oriented disparity modulations. However, for vertically oriented corrugations, only the root mean squared output of a single linear channel explained the data. We suggest that the stereo anisotropy may arise because the stereo system possesses multiple spatial frequency channels for detecting horizontally oriented modulations in horizontal disparity, but only one for vertically oriented modulations.

  8. Tailoring the surface of ZnO nanorods into corrugated nanorods via a selective chemical etch method

    NASA Astrophysics Data System (ADS)

    Duan, Xiangyang; Chen, Guangde; Li, Chu; Yin, Yuan; Jin, Wentao; Guo, Lu'an; Ye, Honggang; Zhu, Youzhang; Wu, Yelong

    2016-07-01

    Using the chemical vapour deposition method, we successfully converted smooth ZnO nanorods (NRs) into corrugated NRs by simply increasing the reaction time. The surface morphology and crystallographic structure of the corrugated NRs were investigated. The corrugated NRs were decorated by alternant (11\\bar{2}1) and (11\\bar{2}\\bar{1}) planes at the exposed side surfaces while the conventional \\{10\\bar{1}0\\} planes disappeared. No twinning boundaries were found in the periodically corrugated structures, indicating that they were type II corrugated NRs. Further investigation told us that they were selectively etched. We introduced a hydrothermal method to synthesize the smooth ZnO NRs and then etched them in a tube furnace at 950 °C with a flow of carbon monoxide. By separating the growth stage and the selective etching stage, we explicitly demonstrated a successfully selective etching effect on ZnO NRs with a carbon monoxide reducing atmosphere for the first time. An etching mechanism based on the selective reaction between carbon monoxide and the different exposed surfaces was proposed. Our results will improve the understanding of the growth mechanism on coarse or corrugated NRs and provide a new strategy for the application of surface controlled nanostructured materials.

  9. Lamb wave band gaps in one-dimensional radial phononic crystal plates with periodic double-sided corrugations

    NASA Astrophysics Data System (ADS)

    Li, Yinggang; Chen, Tianning; Wang, Xiaopeng; Li, Suobin

    2015-11-01

    In this paper, we present the theoretical investigation of Lamb wave propagation in one-dimensional radial phononic crystal (RPC) plates with periodic double-sided corrugations. The dispersion relations, the power transmission spectra, and the displacement fields of the eigenmodes are studied by using the finite element method based on two-dimensional axial symmetry models in cylindrical coordinates. Numerical results show that the proposed RPC plates with periodic double-sided corrugations can yield several band gaps with a variable bandwidth for Lamb waves. The formation mechanism of band gaps in the double-sided RPC plates is attributed to the coupling between the Lamb modes and the in-phase and out-phases resonant eigenmodes of the double-sided corrugations. We investigate the evolution of band gaps in the double-sided RPC plates with the corrugation heights on both sides arranged from an asymmetrical distribution to a symmetrical distribution gradually. Significantly, with the introduction of symmetric double-sided corrugations, the antisymmetric Lamb mode is suppressed by the in-phase resonant eigenmodes of the double-sided corrugations, resulting in the disappearance of the lowest band gap. Furthermore, the effects of the geometrical parameters on the band gaps are further explored numerically.

  10. Variable stiffness corrugated composite structure with shape memory polymer for morphing skin applications

    NASA Astrophysics Data System (ADS)

    Gong, Xiaobo; Liu, Liwu; Scarpa, Fabrizio; Leng, Jinsong; Liu, Yanju

    2017-03-01

    This work presents a variable stiffness corrugated structure based on a shape memory polymer (SMP) composite with corrugated laminates as reinforcement that shows smooth aerodynamic surface, extreme mechanical anisotropy and variable stiffness for potential morphing skin applications. The smart composite corrugated structure shows a low in-plane stiffness to minimize the actuation energy, but also possess high out-of-plane stiffness to transfer the aerodynamic pressure load. The skin provides an external smooth aerodynamic surface because of the one-sided filling with the SMP. Due to variable stiffness of the shape memory polymer the morphing skin exhibits a variable stiffness with a change of temperature, which can help the skin adjust its stiffness according different service environments and also lock the temporary shape without external force. Analytical models related to the transverse and bending stiffness are derived and validated using finite element techniques. The stiffness of the morphing skin is further investigated by performing a parametric analysis against the geometry of the corrugation and various sets of SMP fillers. The theoretical and numerical models show a good agreement and demonstrate the potential of this morphing skin concept for morphing aircraft applications. We also perform a feasibility study of the use of this morphing skin in a variable camber morphing wing baseline. The results show that the morphing skin concept exhibits sufficient bending stiffness to withstand the aerodynamic load at low speed (less than 0.3 Ma), while demonstrating a large transverse stiffness variation (up to 191 times) that helps to create a maximum mechanical efficiency of the structure under varying external conditions.

  11. MTR BUILDING, TRA603. EAST SIDE. CAMERA FACING WEST. CORRUGATED IRON ...

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

    MTR BUILDING, TRA-603. EAST SIDE. CAMERA FACING WEST. CORRUGATED IRON BUILDING MARKED WITH "X" IS TRA-651. TRA-626, TO ITS RIGHT, HOUSED COMPRESSOR EQUIPMENT FOR THE AIRCRAFT NUCLEAR PROPULSION PROGRAM. LATER, IT WAS USED FOR STORAGE. INL NEGATIVE NO. HD46-42-4. Mike Crane, Photographer, April 2005 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  12. Corrugation-pitch-modulated DFB semiconductor lasers realized by common holographic exposure

    NASA Astrophysics Data System (ADS)

    Li, Simin; Li, Lianyan; Shi, Yuechun; Cao, Baoli; Guo, Renjia; Zheng, Junshou; Chen, Xiangfei

    2014-07-01

    Experimental results of corrugation-pitch-modulated (CPM) DFB lasers with distributed phase shift (DPS) based on reconstruction-equivalent-chirp (REC) technique are demonstrated. The DPS can flatten the light intensity distribution along the laser cavity and reduce the spatial hole burning (SHB). The lasers have good single longitudinal mode (SLM) property even under high injection current. Thanks to the sampling technique, the grating can be easily fabricated by holographic exposure and conventional lithograph.

  13. Design and simulation of resonant cavity enhanced corrugated quantum well infrared photodetectors.

    PubMed

    Kim, Jang Pyo; Sarangan, Andrew M

    2006-08-20

    The dipole selection rule limits the maximum achievable efficiency in corrugated quantum well infrared photodetectors (C-QWIPs) to 50%. We consider what is believed to be a novel design that utilizes a resonant cavity enhancement technique to increase the efficiency beyond 50% by rotating the photon polarization at each pass around the cavity. Simulation results show that the quantum efficiency of this device can be enhanced up to 38% compared to that of the standard C-QWIP device.

  14. THz polarization radiation from electrons passing corrugated dielectric tube under non-central propagation

    NASA Astrophysics Data System (ADS)

    Ponomarenko, A. A.; Tishchenko, A. A.; Strikhanov, M. N.

    2017-07-01

    In this work we construct the theory of THz polarization radiation from electrons passing corrugated dielectric tube under non-central propagation. Fully analytical description of spectral and angular properties of radiation is obtained. In calculations we used the method of polarization currents combined with theory of perturbations assuming small distances from the central axis of the tube. Smith-Purcell and Cherenkov mechanisms of radiation are considered and analysed numerically.

  15. Psychometric properties of startle and corrugator response in NPU, affective picture viewing, and resting state tasks.

    PubMed

    Kaye, Jesse T; Bradford, Daniel E; Curtin, John J

    2016-08-01

    The current study provides a comprehensive evaluation of critical psychometric properties of commonly used psychophysiology laboratory tasks/measures within the NIMH RDoC. Participants (N = 128) completed the no-shock, predictable shock, unpredictable shock (NPU) task, affective picture viewing task, and resting state task at two study visits separated by 1 week. We examined potentiation/modulation scores in NPU (predictable or unpredictable shock vs. no-shock) and affective picture viewing tasks (pleasant or unpleasant vs. neutral pictures) for startle and corrugator responses with two commonly used quantification methods. We quantified startle potentiation/modulation scores with raw and standardized responses. We quantified corrugator potentiation/modulation in the time and frequency domains. We quantified general startle reactivity in the resting state task as the mean raw startle response during the task. For these three tasks, two measures, and two quantification methods, we evaluated effect size robustness and stability, internal consistency (i.e., split-half reliability), and 1-week temporal stability. The psychometric properties of startle potentiation in the NPU task were good, but concerns were noted for corrugator potentiation in this task. Some concerns also were noted for the psychometric properties of both startle and corrugator modulation in the affective picture viewing task, in particular, for pleasant picture modulation. Psychometric properties of general startle reactivity in the resting state task were good. Some salient differences in the psychometric properties of the NPU and affective picture viewing tasks were observed within and across quantification methods. © 2016 The Authors. Psychophysiology published by Wiley Periodicals, Inc. on behalf of Society for Psychophysiological Research.

  16. Ohmic losses in coaxial resonators with longitudinal inner-outer corrugation

    SciTech Connect

    Shenyong Hou, A.; Sheng Yu, B.; Hongfu Li, C.; Qixiang Zhao, D.; Xiang Li, E.

    2013-05-15

    In this paper, a coaxial resonator with longitudinal inner-outer corrugation is introduced. Its eigen-equation and expression of ohmic losses are derived. Ohmic losses in the cavity are investigated. Results show that ohmic losses in the outer and inner conductors share a similar variation trend, while the former is larger than the later. What's more, changes of the inner and outer slot depth and width induce different variations of ohmic losses on the surface of the inner and outer conductors.

  17. Effects of Antimicrobial Peptide Revealed by Simulations: Translocation, Pore Formation, Membrane Corrugation and Euler Buckling

    PubMed Central

    Chen, Licui; Jia, Nana; Gao, Lianghui; Fang, Weihai; Golubovic, Leonardo

    2013-01-01

    We explore the effects of the peripheral and transmembrane antimicrobial peptides on the lipid bilayer membrane by using the coarse grained Dissipative Particle Dynamics simulations. We study peptide/lipid membrane complexes by considering peptides with various structure, hydrophobicity and peptide/lipid interaction strength. The role of lipid/water interaction is also discussed. We discuss a rich variety of membrane morphological changes induced by peptides, such as pore formation, membrane corrugation and Euler buckling. PMID:23579956

  18. The characteristics of an intense laser beam propagating in a corrugated plasma channel

    NASA Astrophysics Data System (ADS)

    Tian, Jian-Min; Tang, Rong-An; Hong, Xue-Ren; Yang, Yang; Wang, Li; Zhou, Wei-Jun; Xue, Ju-Kui

    2016-12-01

    The propagation of an intense laser beam in a corrugated plasma channel is investigated. By using the source-dependent expansion technique, an evolution equation of the laser spot size is derived. The behaviors including aperiodic oscillation, resonance, beat-like wave, and periodic oscillation with multipeak are found and analyzed. The formula for the instantaneous wave numbers of these oscillations is obtained. These theoretical findings are confirmed by the final numerical simulation.

  19. Fabrication and evaluation of superplastically formed/weld-brazed corrugated compression panels with beaded webs

    NASA Technical Reports Server (NTRS)

    Royster, D. M.; Davis, R. C.; Shinn, J. M., Jr.; Bales, T. T.; Wiant, H. R.

    1985-01-01

    A study was made to investigate the feasibility of superplastically forming corrugated panels with beaded webs and to demonstrate the structural integrity of these panels by testing. The test panels in the study consist of superplastically formed titanium alloy Ti-6Al-4V half-hat elements that are joined by weld-brazing to titanium alloy Ti-6Al-4V caps to form either single-corrugation compression panels or multiple-corrugation compression panels. Stretching and subsequent thinning of the titanium sheet during superplastic forming is reduced by approximately 35 percent with a shallow half-hat die concept instead of a deep die concept and results in a more uniform thickness across the beaded webs. The complete panels are tested in end compression at room temperature and the results compared with analysis. The heavily loaded panels failed at loads approaching the yield strength of the titanium material. At maximum load, the caps wrinkled locally accompanied with separation of the weld-braze joint in the wrinkle. None of the panels tested, however, failed catastrophically in the weld-braze joint. Experimental test results are in good agreement with structural analysis of the panels.

  20. Design of corrugated-horn-coupled MKID focal plane for CMB B-mode polarization

    NASA Astrophysics Data System (ADS)

    Sekimoto, Yutaro; Sekiguchi, Shigeyuki; Shu, Shibo; Sekine, Masakazu; Nitta, Tom; Naruse, Masato; Dominjon, Agnes; Hasebe, Takashi; Shan, Wenlei; Noguchi, Takashi; Miyachi, Akihira; Mita, Makoto; Kawasaki, Shigeo

    2016-07-01

    A focal plane based on MKID has been designed for cosmic microwave background (CMB) B-mode polarization experiments. We are designing and developing a focal plane with broadband corrugated horn array, planar OMT, 180 degree hybrid, bandpass filters, and MKIDs. The focal plane consists of 3 octave bands (55 - 108 GHz, 80 - 160 GHz, 160 - 320 GHz), 10 hexagonal modules. Broadband corrugated horn-array has been directly machined from an Al block and measured to have a good beam shape which is consistent with electromagnetic field simulations in octave bands. The horn array is designed to be low standing-wave, light weight, and electromagnetic shield. The broadband 4 probes ortho-mode transducer (OMT) is fabricated on Si membrane of an SOI wafer. A broadband 180 degree hybrid made with coplanar waveguide (CPW) is used to reduce higher modes of the circular waveguide. Two bandpass filters of each polarization are patterned with Nb microstrip. A prototype of the broadband corrugated horn coupled MKIDs has been fabricated and tested.

  1. Impact of Atomic Corrugation on Sliding Friction as Probed by QCM

    NASA Astrophysics Data System (ADS)

    Coffey, Tonya; Lee, Sang; Krim, Jacqueline

    2004-03-01

    At the atomic scale, friction is believed to originate primarily via sliding induced excitation of phonons. [1] Theoretical predictions of the magnitude of phononic dissipation have been related to the atomic corrugation of the adsorbate/substrate potential. [2] Braun and colleagues [3] measured a corrugation of 1.9 meV for xenon on a copper(111) surface using helium atom scattering. Using the Quartz Crystal Microbalance (QCM), we have measured the sliding friction of Xe/Cu(111) adsorbed at 77 K. The QCM probe of sliding friction is the sliptime, which measures the slippage of the adsorbate atop the oscillating surface of the QCM. For monolayer coverages, we observed a sliptime of 10 ns for Xe/Cu(111). We also discuss theoretical predictions for the impact of atomic corrugation on sliding friction. [1] Fundamentals of Friction; Macroscopic and Microscopic Processes, ed. I.L. Singer and H.M. Pollock, Kluwer, Dordrecht (1992). [2] M. Cieplak, E.D. Smith, and M.O. Robbins, Science 265 (1994) 1209. [3] J. Braun et al., PRL 80 (1998) 125.

  2. Nonlinear waves on a liquid film falling down an inclined corrugated surface

    NASA Astrophysics Data System (ADS)

    Trifonov, Yuri

    2017-05-01

    In the present study, we performed the direct Navier-Stokes computations on the linear and nonlinear stability of a gravity-driven film flow down an inclined corrugated surface. We focused on the steady-state traveling waves and analyzed their transformations due to the wall corrugations. These solutions have two spatial periods and we have used a double Fourier expansion to compute them. The systematic variations of the Reynolds number and the substrate's periodicity and amplitude were performed in the nonlinear wave analysis. We found that starting from some "critical" values of the Reynolds number, the wall corrugation has a small influence on the film thickness profile of the traveling waves, and it is close to the waves on the liquid film falling down a smooth plate. This "critical" value strongly depends on the substrate's periodicity and amplitude. To our knowledge, this is the first theoretical work where the nonlinear waves on the free surface of a liquid film over the topography is computed using the full Navier-Stokes equations.

  3. Soda-Anthraquinone Durian (Durio Zibethinus Murr.) Rind Linerboard and Corrugated Medium Paper: A Preliminary Test

    NASA Astrophysics Data System (ADS)

    Rizal Masrol, Shaiful; Irwan Ibrahim, Mohd Halim; Adnan, Sharmiza; Mubarak Sa'adon, Amir; Ika Sukarno, Khairil; Fadrol Hisham Yusoff, Mohd

    2017-08-01

    A preliminary test was conducted to investigate the characteristics of linerboard and corrugated medium paper made from durian rind waste. Naturally dried durian rinds were pulped according to Soda-Anthraquinone (Soda-AQ) pulping process with a condition of 20% active alkali, 0.1% AQ, 7:1 liquor to material ratio, 120 minutes cooking time and 170°C cooking temperature. The linerboard and corrugated medium paper with a basis weight of 120 gsm were prepared and evaluated according to Malaysian International Organization for Standardization (MS ISO) and Technical Association of the Pulp and Paper Industry (TAPPI). The results indicate that the characteristics of durian rind linerboard are comparable with other wood or non-wood based paper and current commercial paper. However, low CMT value for corrugated medium and water absorptiveness quality for linerboard could be improved in future. Based on the bulk density (0.672 g/cm3), burst index (3.12 kPa.m2/g) and RCT (2.00 N.m2/g), the durian rind has shown a good potential and suitable as an alternative raw material source for linerboard industry.

  4. High-power tunable laser driven THz generation in corrugated plasma waveguides

    NASA Astrophysics Data System (ADS)

    Miao, Chenlong; Palastro, John P.; Antonsen, Thomas M.

    2017-04-01

    The excitation of Terahertz (THz) radiation by the interaction of an ultrashort laser pulse with the modes of a miniature corrugated plasma waveguide is considered. The axially corrugated waveguide supports the electromagnetic modes with appropriate polarization and subluminal phase velocities that can be phase matched to the ponderomotive potential associated with the laser pulse, making significant THz generation possible. This process is studied via full format Particle-in-Cell simulations that, for the first time, model the nonlinear dynamics of the plasma and the self-consistent evolution of the laser pulse in the case where the laser pulse energy is entirely depleted. It is found that the generated THz is characterized by lateral emission from the channel, with a spectrum that may be narrow or broad depending on the laser intensity. A range of realistic laser pulse and plasma parameters is considered with the goal of maximizing the conversion efficiency of optical energy to THz radiation. As an example, a fixed drive pulse (0.55 J) with a spot size of 15 μm and a duration of 15 fs produces a THz radiation of 37.8 mJ of in a 1.5 cm corrugated plasma waveguide with an on axis average density of 1.4 × 1018 cm-3.

  5. Investigations of heat transfer and friction characteristics of compact cross-corrugated recuperators

    NASA Astrophysics Data System (ADS)

    Zhou, Guo-Yan; Tu, Shan-Tung; Ma, Hu-gen

    2014-09-01

    As one of the key devices in the high temperature gas turbine system, cross-corrugated recuperators provide high heat transfer capabilities with compact size, light weight, strong mechanical strength and are mandatory to achieve 30 % electrical efficiency or higher for micro turbine engines. Flow in such geometries is usually laminar with lower Reynolds numbers. In order to understand mechanisms of flowing and heat transfer, periodic fully developed fluid flow and heat transfer in two types of cross-corrugated structures with inclination angle at 90° are investigated numerically and experimentally. Periodicity was used to reduce the complexity of the channel geometry and enables the smallest possible segment of the flow channel to be modeled. The velocity and temperature distributions were obtained in the three-dimensional complex domain. Besides a detailed flow analysis, comparison of the local heat and mass transfer and the pressure losses for these geometries are presented. It is shown that the flow phenomena caused by the different geometries were of significant influence on the homogeneity and on the quantity of the local heat and mass transfer as well as on the pressure drop. As a recuperator for micro turbine engines, cross-corrugated sinusoidal channels are more preferable to triangular channels.

  6. Corrugated Waveguide and Directional Coupler for CW 250-GHz Gyrotron DNP Experiments

    PubMed Central

    Woskov, Paul P.; Bajaj, Vikram S.; Hornstein, Melissa K.; Temkin, Richard J.; Griffin, Robert G.

    2007-01-01

    A 250-GHz corrugated transmission line with a directional coupler for forward and backward power monitoring has been constructed and tested for use with a 25-W continuous-wave gyrotron for dynamic nuclear polarization (DNP) experiments. The main corrugated line (22-mm internal diameter, 2.4-m long) connects the gyrotron output to the DNP probe input. The directional coupler, inserted approximately midway, is a four-port crossed waveguide beamsplitter design. Two beamsplitters, a quartz plate and ten-wire array, were tested with output coupling of 2.5% (−16 dB) at 250.6 GHz and 1.6% (−18 dB), respectively. A pair of mirrors in the DNP probe transferred the gyrotron beam from the 22-mm waveguide to an 8-mm helically corrugated waveguide for transmission through the final 0.58-m distance inside the NMR magnet to the sample. The transmission-line components were all cold tested with a 248 ± 4-GHz radiometer. A total insertion loss of 0.8 dB was achieved for HE11 -mode propagation from the gyrotron to the sample with only 1% insertion loss for the 22-mm-diameter waveguide. A clean Gaussian gyrotron beam at the waveguide output and reliable forward power monitoring were achieved for many hours of continuous operation. PMID:17901907

  7. Effect of discrete track support by sleepers on rail corrugation at a curved track

    NASA Astrophysics Data System (ADS)

    Jin, X. S.; Wen, Z. F.

    2008-08-01

    The paper investigates into the effect of discrete track support by sleepers on the initiation and development of rail corrugation at a curved track when a railway vehicle passes through using a numerical method. The numerical method considers a combination of Kalker's rolling contact theory with non-Hertzian form, a linear frictional work model and a dynamics model of a half railway vehicle coupled with the curved track. The half-vehicle has a two-axle bogie and doubled suspension systems. It is treated as a full dynamic rigid multi-body model. In the track model, an Euler beam is used to model the rail, and the discrete track support by sleepers moving backward with respect to the vehicle running direction is considered to simulate the effect of the discrete sleeper support on the wheels/rails in rolling contact when the vehicle moves on the track. The sleeper is treated as a rigid body and the ballast bed is replaced with equivalent mass bodies. The numerical analysis exams in detail the variations of wheel/rail normal loads, the creepages, and the rail wear volume along the curved track. Their variations are much concerned with the discrete track support. The numerical results show that the discrete track support causes the fluctuating of the normal loads and creepages at a few frequencies. These frequencies comprise the passing frequency of the sleepers and the excited track resonant frequencies, which are higher than the sleeper passing frequency. Consequently, rail corrugation with several wavelengths initiates and develops. Also the results show that the contact vibrating between the curved rails and the four wheels of the same bogie has different frequencies. In this way, the different key frequencies to be excited play an important role in the initiation and development of curved rail corrugation. Therefore, the corrugations caused by the four wheels of the same bogie present different wavelengths. The paper shows and discusses the depths of the initial

  8. Six Centuries Old Spiral of Vertical Corrugations in Saturn's C-Ring

    NASA Astrophysics Data System (ADS)

    Marouf, E. A.; French, R. G.; Rappaport, N. J.; Wong, K.; McGhee, C.; Anabtawi, A.

    2011-12-01

    Likely evidence of nearly six centuries old collision of captured cometary material with Saturn's Ring C is uncovered in recent Cassini Radio Science ring observations. Three Cassini ring occultation experiments were especially designed so that radio signals transmitted by Cassini to the Earth pass through the rings when the rings are nearly closed as viewed by the ground receiving stations of the NASA Deep Space Network (DSN). In this special geometry, the long path of the radio signals through the rings enhances sensitivity to detection of very tenuous ring material and allows ~400 meters resolution profiling of its radial structure. The observations uncover previously undetectable quasi-periodic optical depth undulations in 4 sub-regions of the innermost ~4000 km of Ring C (~74,480-77,740 km). The structure modulates a tenuous background optical depth of ~0.05 and has peak-to-peak fluctuations < ~0.01, making detection possible only in the case of these 3 special occultations (ring opening angle of 4.8, 4.8, and 1.9 degrees; Cassini Revs 123, 125, and 133, respectively). The structure is detectable at two observation wavelengths (0.94 and 3.6 cm), at multiple observing DSN ground stations, and in data from all 3 occultations. It's characterized by two interfering "tones" of spatial wavelength ~1.3 and ~1.2 km. The wavelength increases slowly with ring radius. The behavior appears consistent with presence of vertical corrugations 4-10 meters in height likely caused by a past ring tilting event (collision with cometary debris) and subsequent differential nodal regression of particle orbits. Time evolution of the perturbations creates a tightly wound spiral pattern of ring height variations which when probed by the radio signals yield the observed tenuous quasi-periodic optical depth fluctuations. The corrugations model was proposed by Hedman et al. [Science 332, 2011] to explain intriguing 30-50 km wavelength structure observed in Cassini images (ISS) across Ring

  9. Noncontact gears. I. Next-to-leading order contribution to the lateral Casimir force between corrugated parallel plates

    SciTech Connect

    Cavero-Pelaez, Ines; Milton, Kimball A.; Parashar, Prachi; Shajesh, K. V.

    2008-09-15

    We calculate the lateral Casimir force between corrugated parallel plates, described by {delta}-function potentials, interacting through a scalar field, using the multiple scattering formalism. The contributions to the Casimir energy due to uncorrugated parallel plates is treated as a background from the outset. We derive the leading- and next-to-leading-order contribution to the lateral Casimir force for the case when the corrugation amplitudes are small in comparison to corrugation wavelengths. We present explicit results in terms of finite integrals for the case of the Dirichlet limit, and exact results for the weak-coupling limit, for the leading- and next-to-leading-orders. The correction due to the next-to-leading contribution is significant. In the weak coupling limit we calculate the lateral Casimir force exactly in terms of a single integral which we evaluate numerically. Exact results for the case of the weak limit allows us to estimate the error in the perturbative results. We show that the error in the lateral Casimir force, in the weak coupling limit, when the next-to-leading order contribution is included is remarkably low when the corrugation amplitudes are small in comparison to corrugation wavelengths. We expect similar conclusions to hold for the Dirichlet case. The analogous calculation for the electromagnetic case should reduce the theoretical error sufficiently for comparison with the experiments.

  10. Numerical analysis of the laminar forced convective heat transfer in coiled tubes with periodic ring-type corrugation

    NASA Astrophysics Data System (ADS)

    Vocale, Pamela; Mocerino, Andrea; Bozzoli, Fabio; Rainieri, Sara

    2016-09-01

    Wall curvature and wall corrugation represent two of the most used passive techniques to enhance convective heat transfer. The effectiveness of wall curvature is due to the fact that it gives origin to a secondary fluid motion orthogonal to the main flow, while wall corrugation is used to disrupt the development of the boundary layers, by enhancing the convective heat transfer mechanism. The compound use of the two techniques has been investigated in literature, mainly experimentally, but further investigation is still needed. In particular, it has been experimentally observed that this compound enhancement technique brings an additional heat transfer augmentation in the majority of applications whereas in the very low Reynolds number range the surface average performances of corrugated coils are lower than the one shown by smooth wall coils. This paper deepened the knowledge on this phenomenon presenting a numerical investigation of the effect induced by a periodic ring-type corrugation on the laminar convective heat transfer in coiled tubes. The study considered the laminar flow in the Reynolds and Dean number range 25-100 and 6-24 respectively. The investigation was particularly focused on the Dean's vortices destruction mechanism, induced by the wall corrugation and on the consequent breakdown of the average Nusselt number.

  11. Non-binding conductor load bearing roller for a gas-insulated transmission line having a corrugated outer conductor

    DOEpatents

    Fischer, William H.

    1984-01-01

    A gas-insulated transmission line includes a corrugated outer conductor, an inner conductor disposed within and insulated from the outer conductor by means of support insulators and an insulating gas, and a non-binding transport device for supporting and permitting movement of the inner conductor/insulating support assembly axially along the corrugated outer conductor without radial displacement and for moving without binding along corrugations of any slope less than vertical. The transport device includes two movable contacts, such as skids or rollers, supported on a common pivot lever, the pivot lever being rotatably disposed about a pivot lever axis, which pivot lever axis is in turn disposed on the periphery of a support insulator or particle trap if one is used. The movable contacts are separated axially a distance equal to the axial distance between the peaks and valleys of the corrugations of the outer conductor and separated radially a distance equal to the radial distance between the peaks and valleys of the corrugations of the outer conductor. The transport device has the pivot lever axis disposed parallel to the motion of travel of the inner conductor/insulating support assembly.

  12. Non-binding conductor load bearing roller for a gas-insulated transmission line having a corrugated outer conductor

    SciTech Connect

    Fischer, W.H.

    1984-04-24

    A gas-insulated transmission line includes a corrugated outer conductor, an inner conductor disposed within and insulated from the outer conductor by means of support insulators and an insulating gas, and a non-binding transport device for supporting and permitting movement of the inner conductor/insulating support assembly axially along the corrugated outer conductor without radial displacement and for moving without binding along corrugations of any slope less than vertical. The transport device includes two movable contacts, such as skids or rollers, supported on a common pivot lever, the pivot lever being rotatably disposed about a pivot lever axis, which pivot lever axis is in turn disposed on the periphery of a support insulator or particle trap if one is used. The movable contacts are separated axially a distance equal to the axial distance between the peaks and valleys of the corrugations of the outer conductor and separated radially a distance equal to the radial distance between the peaks and valleys of the corrugations of the outer conductor. The transport device has the pivot lever axis disposed parallel to the motion of travel of the inner conductor/insulating support assembly. 7 figs.

  13. Spoof surface plasmon modes on doubly corrugated metal surfaces at terahertz frequencies

    NASA Astrophysics Data System (ADS)

    Liu, Yong-Qiang; Kong, Ling-Bao; Du, Chao-Hai; Liu, Pu-Kun

    2016-06-01

    Spoof surface plasmons (SSPs) have many potential applications such as imaging and sensing, communications, innovative leaky wave antenna and many other passive devices in the microwave and terahertz (THz) spectrum. The extraordinary properties of SSPs (e.g. extremely strong near field, enhanced beam-wave interaction) make them especially attractive for developing novel THz electronic sources. SSP modes on doubly corrugated metal surfaces are investigated and analyzed both theoretically and numerically in this paper. The analytical SSP dispersion expressions of symmetric and anti-symmetric modes are obtained with a simplified modal field expansion method; the results are also verified by the finite integration method. Additionally, the propagation losses are also considered for real copper surfaces with a limited constant conductivity in a THz regime. It is shown that the asymptotical frequency of the symmetric mode at the Brillouin boundary decreases along with the decreased gap size between these two corrugated metal surfaces while the asymptotical frequency increases for the anti-symmetric mode. The anti-symmetric mode demonstrates larger propagation losses than the symmetric mode. Further, the losses for both symmetric and anti-symmetric modes decrease when this gap size enlarges. By decreasing groove depth, the asymptotical frequency increases for both the symmetric and the anti-symmetric mode, but the variation of propagation losses is more complicated. Propagation losses increase along with the increased period. Our studies on the dispersion characteristics and propagation losses of SSP modes on this doubly corrugated metallic structure with various parameters is instructive for numerous applications such as waveguides, circuitry systems with high integration, filters and powerful electronic sources in the THz regime.

  14. Eddy Current System for Detection of Cracking Beneath Braiding in Corrugated Metal Hose

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz; Simpson, John; Hall, George

    2008-01-01

    In this paper an eddy current system for the detection of partially-through-the-thickness cracks in corrugated metal hose is presented. Design criteria based upon the geometry and conductivity of the part are developed and applied to the fabrication of a prototype inspection system. Experimental data are used to highlight the capabilities of the system and an image processing technique is presented to improve flaw detection capabilities. A case study for detection of cracking damage in a space shuttle radiator retract flex hoses is also presented.

  15. Analysis of Bonded Joints Between the Facesheet and Flange of Corrugated Composite Panels

    NASA Technical Reports Server (NTRS)

    Yarrington, Phillip W.; Collier, Craig S.; Bednarcyk, Brett A.

    2008-01-01

    This paper outlines a method for the stress analysis of bonded composite corrugated panel facesheet to flange joints. The method relies on the existing HyperSizer Joints software, which analyzes the bonded joint, along with a beam analogy model that provides the necessary boundary loading conditions to the joint analysis. The method is capable of predicting the full multiaxial stress and strain fields within the flange to facesheet joint and thus can determine ply-level margins and evaluate delamination. Results comparing the method to NASTRAN finite element model stress fields are provided illustrating the accuracy of the method.

  16. EDDY CURRENT SYSTEM FOR DETECTION OF CRACKING BENEATH BRAIDING IN CORRUGATED METAL HOSE

    SciTech Connect

    Wincheski, Buzz; Simpson, John; Hall, George

    2009-03-03

    In this paper an eddy current system for the detection of partially-through-the-thickness cracks in corrugated metal hose is presented. Design criteria based upon the geometry and conductivity of the part are developed and applied to the fabrication of a prototype inspection system. Experimental data are used to highlight the capabilities of the system and an image processing technique is presented to improve flaw detection capabilities. A case study for detection of cracking damage in a space shuttle radiator retract flex hoses is also presented.

  17. Spectral characteristics of distributed feedback semiconductor laser and their improvements by corrugation-pitch-modulated structure

    NASA Astrophysics Data System (ADS)

    Okai, Makoto

    1994-01-01

    This paper presents a review of a theoretical analysis problems that occur with single-mode lasers, and a novel laser structure for superstable single-mode operation. Also presented is a new grating-fabrication technique termed photo-mask self-interference, to fabricate corrugation-pitch-modulated (CPM) structures, for enhancing the stability of the longitudinal single-mode operation in distributed feedback lasers (DFB). It is seen that the CPM-DFB laser developed for coherent transmission systems displays the narrowest spectral linewidth (56 kHz) reported so far for a semiconductor.

  18. Distributed-feedback Terahertz Quantum-cascade Lasers with Laterally Corrugated Metal Waveguides

    NASA Technical Reports Server (NTRS)

    Williams, Benjamin S.; Kumar, Sushil; Hu, Qing; Reno, John L.

    2005-01-01

    We report the demonstration of distributed-feedback terahertz quantum-cascade lasers based on a first-order grating fabricated via a lateral corrugation in a double-sided metal ridge waveguide. The phase of the facet reflection was precisely set by lithographically defined facets by dry etching. Single-mode emission was observed at low to moderate injection currents, although multimode emission was observed far beyond threshold owing to spatial hole burning. Finite-element simulations were used to calculate the modal and threshold characteristics for these devices, with results in good agreement with experiments.

  19. Unsteady mixed convective flow and heat transfer in a vertical corrugated channel with composite porous media

    NASA Astrophysics Data System (ADS)

    Umavathi, J. C.; Shekar, M.

    2013-07-01

    An unsteady mixed convective flow and heat transfer in a vertical corrugated channel containing porous and fluid layers are considered. The equations of momentum and energy are solved under appropriate boundary and interface conditions with the assumption that the solution consists of a mean part and a perturbed one. The exact solutions are obtained in the long-wave approximation. Separate solutions are matched at the interface with the use of suitable matching conditions. The effects of pertinent parameters, such as the Grashof number, viscosity ratio, width ratio, conductivity ratio, frequency, and the wave parameter on the flow field and heat transfer characteristics are studied.

  20. An optical fiber Fabry-Perot pressure sensor using corrugated diaphragm and angle polished fiber

    NASA Astrophysics Data System (ADS)

    Zhu, Jiali; Wang, Ming; Chen, Lu; Ni, Xiaoqi; Ni, Haibin

    2017-03-01

    In this paper, a Fabry-Perot pressure sensor using a corrugated diaphragm and angle polished fiber is proposed. A SU-8 structure using two step of lithography is formed to fix the polished fiber, which helps control the cavity length precisely. The fabrication process is described. The characteristics of both pressure and temperature are tested. Also the temperature compensation is realized. Experimental results show that the sensor has high sensitivity and good linearity over the pressure range of 0-0.1 MPa. The sensitivity (change in cavity/loaded pressure) is 705.64 μm/MPa.

  1. Argon multilayers on a corrugated surface: effect of coverage on structure

    NASA Astrophysics Data System (ADS)

    Khandkar, M. D.; Balasubramanian, S.

    2002-08-01

    Crystalline layers of a simple, monoatomic fluid on a corrugated surface are studied using the molecular dynamics method. The structure of the first adsorbed layer at monolayer and multilayer coverages is examined. We observe a lateral compression of the first layer of the adsorbate lattice for bilayer coverage, relative to the monolayer coverage. This compression is largely driven by adsorbate-substrate interactions, and is most pronounced when the monolayer is incommensurate with the underlying substrate lattice. The results are consistent with neutron diffraction data of n-alkane molecules on graphite.

  2. Radiation characteristics of electromagnetic eigenmodes at the corrugated interface of a left-handed material.

    PubMed

    Cuevas, Mauro; Depine, Ricardo A

    2009-08-28

    We study the radiation characteristics of electromagnetic surface waves at a periodically corrugated interface between a conventional and a negatively refracting (or left-handed) material. In this case, and contrary to the surface plasmon polariton in a metallic grating, surface plasmon polaritons may radiate on both sides of the rough interface along which they propagate. We find novel radiation regimes which provide an indirect demonstration of other unusual phenomena characteristic of electromagnetic wave propagation in left-handed materials, such as negative refraction or backward wave propagation.

  3. Dual nature of localization in guiding systems with randomly corrugated boundaries: Anderson-type versus entropic

    SciTech Connect

    Tarasov, Yu.V. Shostenko, L.D.

    2015-05-15

    A unified theory for the conductance of an infinitely long multimode quantum wire whose finite segment has randomly rough lateral boundaries is developed. It enables one to rigorously take account of all feasible mechanisms of wave scattering, both related to boundary roughness and to contacts between the wire rough section and the perfect leads within the same technical frameworks. The rough part of the conducting wire is shown to act as a mode-specific randomly modulated effective potential barrier whose height is governed essentially by the asperity slope. The mean height of the barrier, which is proportional to the average slope squared, specifies the number of conducting channels. Under relatively small asperity amplitude this number can take on arbitrary small, up to zero, values if the asperities are sufficiently sharp. The consecutive channel cut-off that arises when the asperity sharpness increases can be regarded as a kind of localization, which is not related to the disorder per se but rather is of entropic or (equivalently) geometric origin. The fluctuating part of the effective barrier results in two fundamentally different types of guided wave scattering, viz., inter- and intramode scattering. The intermode scattering is shown to be for the most part very strong except in the cases of (a) extremely smooth asperities, (b) excessively small length of the corrugated segment, and (c) the asperities sharp enough for only one conducting channel to remain in the wire. Under strong intermode scattering, a new set of conducting channels develops in the corrugated waveguide, which have the form of asymptotically decoupled extended modes subject to individual solely intramode random potentials. In view of this fact, two transport regimes only are realizable in randomly corrugated multimode waveguides, specifically, the ballistic and the localized regime, the latter characteristic of one-dimensional random systems. Two kinds of localization are thus shown to

  4. Analysis of corrugated cardboard influence on the protective properties of complex packaging system

    NASA Astrophysics Data System (ADS)

    Osowski, Przemyslaw; Piatkowski, Tomasz

    2017-03-01

    According to available literature, it is assumed that outer packaging container, which is usually made of corrugated cardboard, does not influence the mitigation of the impact effects, thus in the designing process of packaging system the outer packaging is skipped. The purpose of this paper is to verify the above assumption, including determination of the influence of the 5-layer cardboard on the properties of structures that consist of that cardboard and polyethylene foam. Verification is performed with the use of the finite element method. To apply this method the dynamic compression curve of cushioning material is required. Therefore in the paper it is also presented the modified method to determine the curve.

  5. Importance of anisotropy on design of compression-loaded composite corrugated panels

    NASA Technical Reports Server (NTRS)

    Gurdal, Zafer; Young, Richard D.

    1990-01-01

    An investigation is conducted of the importance of anisotropic terms in the design of composite corrugated panels, for a range of axial compressive load intensities. The two panel configurations treated were panels with tailored laminates and panels with a continuous laminate; both are of interest to aircraft designers and prone to anisotropic effects which are of as-yet undetermined extent. The importance of the anisotropic terms is measured by the difference between the design load and the buckling load obtained from the ultimate structural analysis.

  6. Shear Lag in Corrugated Sheets Used for the Chord Member of a Box Beam

    NASA Technical Reports Server (NTRS)

    Newell, Joseph S; Reissner, Eric

    1941-01-01

    The problem of the distribution of normal stress across a wide corrugated sheet used as the chord of a box-beam-like structure is investigated theoretically and experimentally. Expressions are developed giving the stress distribution in beams, symmetrical or unsymmetrical, about a plane passed spanwise through the center of the sheet. The experiments were arranged to insure bending without torsion and surveys of the normal stresses were made by means of mechanical and electrical strain gages. The experimental data showed very good agreement with the new b of the theoretical curves, especially at the highly stressed sections, for both the symmetrical and unsymmetrical beams. Several suggestions for future research are included.

  7. Mechanisms of Čerenkov Superradiance of Extended Electron Bunches in Oversized Corrugated Waveguides

    NASA Astrophysics Data System (ADS)

    Ginzburg, N. S.; Zaslavsky, V. Yu.; Zheleznov, I. V.; Zotova, I. V.; Malkin, A. M.; Sergeev, A. S.; Kocharovskaya, E. R.; Yalandin, M. I.

    2016-11-01

    We propose to use the effect of Čerenkov superradiance of the electromagnetic field by extended electron bunches, which move linearly in oversized corrugated waveguides, for generation of multimegawatt subnanosecond pulses in the short-wave part of the millimeter-wavelength band. Various mechanisms of generation of superradiance pulses are considered, including excitation of volume waves in the case of electron synchronism with a decelerated spatial harmonic, as well as excitation of copropagating and counterpropagating surface waves. The analysis was performed both within the framework of the quasioptical approximation and on the basis of direct modeling by the particle-in-cell method.

  8. A study of structurally efficient graphite-thermoplastic trapezoidal-corrugation sandwich and semi-sandwich panels

    NASA Technical Reports Server (NTRS)

    Jegley, Dawn C.

    1993-01-01

    The structural efficiency of compression-loaded trapezoidal-corrugation sandwich and semi-sandwich composite panels is studied to determine their weight savings potential. Sandwich panels with two identical face sheets and a trapezoidal corrugated core between them, and semi-sandwich panels with a corrugation attached to a single skin are considered. An optimization code is used to find the minimum weight designs for critical compressive load levels ranging from 3,000 to 24,000 lb/in. Graphite-thermoplastic panels based on the optimal minimum weight designs were fabricated and tested. A finite-element analysis of several test specimens was also conducted. The results of the optimization study, the finite-element analysis, and the experiments are presented.

  9. Botulinum Toxin Type-A (BoNT-A) Injections of the Corrugator Muscles for Aesthetics and Depression?

    PubMed

    Brennan, Connie

    The treatment of glabellar lines with botulinum toxin type-A (BoNT-A) is a staple for aesthetic providers who specialize in facial rejuvenation. Clinical efforts are currently underway to substantiate upper facial injections (the corrugator muscles are the target muscles) of BoNT-A as an antidepression therapy. This article describes the origin of "facial feedback" by Charles Darwin nearly 150 years ago, as well as "emotional proprioception"-2 neuroanatomical concepts that help provide the scientific rationale behind the general influence facial muscles have on the emotional centers of the brain, and, specifically, how the corrugator muscles-involved with frowning-promote a gloomy mood. The journey researchers have taken to clinically qualify BoNT-A injections of the corrugator muscles-to inhibit frowning, and thereby mitigate depression-will also be highlighted so that aesthetic providers are up to date on this emerging benefit of BoNT-A.

  10. Using the nanoimprint-in-metal method to prepare corrugated metal structures for plasmonic biosensors through both surface plasmon resonance and index-matching effects.

    PubMed

    Yu, Chen-Chieh; Ho, Kuan-Hung; Chen, Hsuen-Li; Chuang, Shang-Yu; Tseng, Shao-Chin; Su, Wei-Fang

    2012-03-15

    In this study, we prepared metallic corrugated structures for use as highly sensitive plasmonic sensors. Relying on the direct nanoimprint-in-metal method, fabrication of this metallic corrugated structure was readily achieved in a single step. The metallic corrugated structures were capable of sensing both surface plasmon resonance (SPR) wavelengths and index-matching effects. The corrugated Au films exhibited high sensitivity (ca. 800 nm/RIU), comparable with or even higher than those of other reported SPR-based sensors. Because of the unique index-matching effect, refractometric sensing could also be performed by measuring the transmission intensity of the Au/substrate SPR mode-conveniently, without a spectrometer. In the last, we demonstrated the corrugated Au film was capable of sensing biomolecules, revealing the ability of the structure to be a highly sensitive biosensor.

  11. Providing plastic zone extrusion

    DOEpatents

    Manchiraju, Venkata Kiran; Feng, Zhili; David, Stan A.; Yu, Zhenzhen

    2017-04-11

    Plastic zone extrusion may be provided. First, a compressor may generate frictional heat in stock to place the stock in a plastic zone of the stock. Then, a conveyer may receive the stock in its plastic zone from the compressor and transport the stock in its plastic zone from the compressor. Next, a die may receive the stock in its plastic zone from the conveyer and extrude the stock to form a wire.

  12. Atomic-scale friction modulated by potential corrugation in multi-layered graphene materials

    SciTech Connect

    Zhuang, Chunqiang; Liu, Lei

    2015-03-21

    Friction is an important issue that has to be carefully treated for the fabrication of graphene-based nano-scale devices. So far, the friction mechanism of graphene materials on the atomic scale has not yet been clearly presented. Here, first-principles calculations were employed to unveil the friction behaviors and their atomic-scale mechanism. We found that potential corrugations on sliding surfaces dominate the friction force and the friction anisotropy of graphene materials. Higher friction forces correspond to larger corrugations of potential energy, which are tuned by the number of graphene layers. The friction anisotropy is determined by the regular distributions of potential energy. The sliding along a fold-line path (hollow-atop-hollow) has a relatively small potential energy barrier. Thus, the linear sliding observed in macroscopic friction experiments may probably be attributed to the fold-line sliding mode on the atomic scale. These findings can also be extended to other layer-structure materials, such as molybdenum disulfide (MoS{sub 2}) and graphene-like BN sheets.

  13. Energy corrugation in atomic-scale friction on graphite revisited by molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Sun, Xiao-Yu; Qi, Yi-Zhou; Ouyang, Wengen; Feng, Xi-Qiao; Li, Qunyang

    2016-08-01

    Although atomic stick-slip friction has been extensively studied since its first demonstration on graphite, the physical understanding of this dissipation-dominated phenomenon is still very limited. In this work, we perform molecular dynamics (MD) simulations to study the frictional behavior of a diamond tip sliding over a graphite surface. In contrast to the common wisdom, our MD results suggest that the energy barrier associated lateral sliding (known as energy corrugation) comes not only from interaction between the tip and the top layer of graphite but also from interactions among the deformed atomic layers of graphite. Due to the competition of these two subentries, friction on graphite can be tuned by controlling the relative adhesion of different interfaces. For relatively low tip-graphite adhesion, friction behaves normally and increases with increasing normal load. However, for relatively high tip-graphite adhesion, friction increases unusually with decreasing normal load leading to an effectively negative coefficient of friction, which is consistent with the recent experimental observations on chemically modified graphite. Our results provide a new insight into the physical origins of energy corrugation in atomic scale friction.

  14. Giant apparent lattice distortions in STM images of corrugated sp2-hybridised monolayers

    NASA Astrophysics Data System (ADS)

    Dubout, Q.; Calleja, F.; Sclauzero, G.; Etzkorn, M.; Lehnert, A.; Claude, L.; Papagno, M.; Natterer, F. D.; Patthey, F.; Rusponi, S.; Pasquarello, Alfredo; Brune, H.

    2016-10-01

    We report on the strengths and limitations of scanning tunnelling microscopy (STM) when used for characterising atomic-scale features of quasi two-dimensional materials, such as graphene and single layers of hexagonal boron nitride, which may present strong corrugations when grown epitaxially on a substrate with a lattice mismatch. As a paradigmatic test case, we choose single-layer and bilayer graphene on Ru(0001), because their STM images show both a long-range moiré modulation and complex atomic-scale distortions of the graphene lattice. Through high-resolution STM measurements, we first determine with high accuracy the moiré epitaxial relations of the single layer and the bilayer with respect to the metal substrate. In particular, we also provide direct evidence for the existence of AA-stacked bilayer graphene domains on Ru(0001). We then demonstrate that the local strain distribution, as inferred from the same STM images, can be affected by large errors, so that apparent giant strains arise in some regions of the moiré as an imaging artefact. With the aid of density functional theory simulations, we track down the origin of these fictitious distortions in the high directionality of the graphene π-orbital density combined with the large corrugation of the sample. The proposed theoretical model correctly accounts for the observed dependence of the apparent strain on the STM tip-sample separation and on the different degree of curvature of the second graphene layer with respect to the single layer.

  15. Nanophase coexistence and sieving in binary mixtures confined between corrugated walls

    SciTech Connect

    Curry, J.E.; Cushman, J.H.

    1995-08-08

    The grand canonical Monte Carlo method is used to study a binary mixture of Lennard-Jones atoms confined to a corrugated slit micropore which is in thermodynamic equilibrium with its bulk phase counterpart. The micropore has atomically structured walls; one of the which possesses nanoscale structure in the form of rectilinear grooves (corrugation). The grooved surface divides the confined fluid film into two strip shaped regions, that inside and that outside the grooves. Transverse solidlike order in the film gives rise to shear stress. Transverse order coupled with packing restrictions give rise to a difference between the pore and bulk fluid mixture compositions. Solidlike order may appear within the grooves only, outside the grooves only, or in both regions simultaneously. As the relative alignment of the walls is shifted the pore fluid undergoes freeze--thaw cycles in one or both regions with associated changes in the shear stress and pore fluid composition. The degree of transverse order in the film is less than would be expected in a pure Lennard-Jones film and fluid-solid phase transitions are gradual as opposed to sudden as seen in pure Lennard-Jones films. The magnitude of the shear stress is greatest when a fluid--solid phase transition occurs in both regions of the pore. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  16. Corrugation of Phase-Separated Lipid Bilayers Supported by Nanoporous Silica Xerogel Surfaces

    SciTech Connect

    Goksu, E I; Nellis, B A; Lin, W; Satcher Jr., J H; Groves, J T; Risbud, S H; Longo, M L

    2008-10-30

    Lipid bilayers supported by substrates with nanometer-scale surface corrugations holds interest in understanding both nanoparticle-membrane interactions and the challenges of constructing models of cell membranes on surfaces with desirable properties, e.g. porosity. Here, we successfully form a two-phase (gel-fluid) lipid bilayer supported by nanoporous silica xerogel. Surface topology, diffusion, and lipid density in comparison to mica-supported lipid bilayers were characterized by AFM, FRAP, FCS, and quantitative fluorescence microscopy, respectively. We found that the two-phase lipid bilayer follows the xerogel surface contours. The corrugation imparted on the lipid bilayer results in a lipid density that is twice that on a flat mica surface. In direct agreement with the doubling of actual bilayer area in a projected area, we find that the lateral diffusion coefficient (D) of lipids on xerogel ({approx}1.7 {micro}m{sup 2}/s) is predictably lower than on mica ({approx}4.1 {micro}m{sup 2}/s) by both FRAP and FCS techniques. Furthermore, the gel-phase domains on xerogel compared to mica were larger and less numerous. Overall, our results suggest the presence of a relatively defect-free continuous two-phase bilayer that penetrates approximately midway into the first layer of {approx}50 nm xerogel beads.

  17. Inkjet printing of UHF antennas on corrugated cardboards for packaging applications

    NASA Astrophysics Data System (ADS)

    Sowade, Enrico; Göthel, Frank; Zichner, Ralf; Baumann, Reinhard R.

    2015-03-01

    In this study, a method based on inkjet printing has been established to develop UHF antennas on a corrugated cardboard for packaging applications. The use of such a standardized, paper-based packaging substrate as material for printing electronics is challenging in terms of its high surface roughness and high ink absorption rate, especially when depositing very thin films with inkjet printing technology. However, we could obtain well-defined silver layers on the cardboard substrates due to a primer layer approach. The primer layer is based on a UV-curable ink formulation and deposited as well as the silver ink with inkjet printing technology. Industrial relevant printheads were chosen for the deposition of the materials. The usage of inkjet printing allows highest flexibility in terms of pattern design. The primer layer was proven to optimize the surface characteristics of the substrate, mainly reducing the surface roughness and water absorptiveness. Thanks to the primer layer approach, ultra-high-frequency (UHF) radio-frequency identification (RFID) antennas were deposited by inkjet printing on the corrugated cardboards. Along with the characterization and interpretation of electrical properties of the established conductive antenna patterns, the performance of the printed antennas were analyzed in detail by measuring the scattering parameter S11 and the antenna gain.

  18. High-Power Tunable Laser Pulse Driven Terahertz Generation in Corrugated Plasma Waveguides

    NASA Astrophysics Data System (ADS)

    Miao, Chenlong; Palastro, John; Antonsen, Thomas

    2016-10-01

    Excitation of terahertz radiation by the interaction of an ultra-short laser pulse and the fields of a miniature, corrugated plasma waveguide is considered. Plasma structures of this type have been realized experimentally and they can support electromagnetic (EM) channel modes with properties that allow for radiation generation. In particular, the mode have subluminal field components, thus allowing phase matching between the generated THz modes and the ponderomotive potential of the laser pulse. Theoretical analysis and full format PIC simulations are conducted. We find THz generated by this slow wave phase matching mechanism is characterized by lateral emission and a coherent, narrow band, tunable spectrum with relatively high power and conversion efficiency. We investigated two different types of channels, and a range of realistic laser pulses and plasma profile parameters are considered with the goal of increasing the conversion of optical energy to THz radiation. We find high laser intensities strongly modify the THz spectrum by exciting higher order channel modes. Enhancement of a specific channel mode can be realized by using an optimum pulse duration and plasma density. As an example, a fixed drive pulse (0.55 J) with spot size of 15 µm and pulse duration of 15 fs excites 37.8 mJ of THz radiation in a 1.5 cm corrugated plasma waveguide with on axis average density of 1.4×1018cm-3, conversion efficiency exceeding 8% is achieved.

  19. Strain Superlattices and Macroscale Suspension of Graphene Induced by Corrugated Substrates

    NASA Astrophysics Data System (ADS)

    Reserbat-Plantey, Antoine; Kalita, Dipankar; Han, Zheng; Ferlazzo, Laurence; Autier-Laurent, Sandrine; Komatsu, Katsuyoshi; Li, Chuan; Weil, Raphaël; Ralko, Arnaud; Marty, Laëtitia; Guéron, Sophie; Bendiab, Nedjma; Bouchiat, Hélène; Bouchiat, Vincent

    2014-09-01

    We investigate the organized formation of strain, ripples and suspended features in macroscopic CVD-prepared graphene sheets transferred onto a corrugated substrate made of an ordered arrays of silica pillars of variable geometries. Depending on the aspect ratio and sharpness of the corrugated array, graphene can conformally coat the surface, partially collapse, or lay, fakir-like, fully suspended between pillars over tens of micrometers. Upon increase of pillar density, ripples in collapsed films display a transition from random oriented pleats emerging from pillars to ripples linking nearest neighboring pillars organized in domains of given orientation. Spatially-resolved Raman spectroscopy, atomic force microscopy and electronic microscopy reveal uniaxial strain domains in the transferred graphene, which are induced and controlled by the geometry. We propose a simple theoretical model to explain the transition between suspended and collapsed graphene. For the arrays with high aspect ratio pillars, graphene membranes stays suspended over macroscopic distances with minimal interaction with pillars tip apex. It offers a platform to tailor stress in graphene layers and open perspectives for electron transport and nanomechanical applications.

  20. Study of the effects of corrugated wall structures due to blanket modules around ICRH antennas

    SciTech Connect

    Dumortier, Pierre; Louche, Fabrice; Messiaen, André; Vervier, Michel

    2014-02-12

    In future fusion reactors, and in ITER, the first wall will be covered by blanket modules. These blanket modules, whose dimensions are of the order of the ICRF wavelengths, together with the clearance gaps between them will constitute a corrugated structure which will interact with the electromagnetic waves launched by ICRF antennas. The conditions in which the grooves constituted by the clearance gaps between the blanket modules can become resonant are studied. Simple analytical models and numerical simulations show that mushroom type structures (with larger gaps at the back than at the front) can bring down the resonance frequencies, which could lead to large voltages in the gaps between the blanket modules and perturb the RF properties of the antenna if they are in the ICRF operating range. The effect on the wave propagation along the wall structure, which is acting as a spatially periodic (toroidally and poloidally) corrugated structure, and hence constitutes a slow wave structure modifying the wall boundary condition, is examined.

  1. Packaged symmetric/asymmetric corrugated long period fiber gratings for refractive index sensing applications

    NASA Astrophysics Data System (ADS)

    Huang, Chih-Yu; Chan, Wen-Lin; Chuo, Shih-Min; Chang, Jer-Haur; Chen, Li-Lun; Wang, Lon A.

    2009-10-01

    We demonstrate a new method that could make possible the mass production of symmetric and asymmetric corrugated long period fiber gratings (C-LPFG) by utilizing hot embossing and imprint lithography on polycarbonate (PC). The poly-dimethylsiloxane (PDMS) is imprinted on PC to create the periodic revealed region of fiber for hydrofluoric acid (HF) etching. The asymmetric C-LPFGs show some unique optical characteristics of two separate dips due to their asymmetric structures. After the torsion, the second dip would be gone and the first one would begin to shift toward shorter wavelength. It is assumed that the asymmetric C-LPFG behaves similar to the symmetric one with the torsion of a full circle. A C-LPFG was well packaged by fixing itself in the PC and having some open area close to the fiber to receive the liquid under test. The corrugated structures close to the fiber core were covered by the liquid that the packaged refractive index sensor has the sensitivity of 26.7 nm/RIU.

  2. Design and Fabrication of a Ring-Stiffened Graphite-Epoxy Corrugated Cylindrical Shell

    NASA Technical Reports Server (NTRS)

    Johnson, R., Jr.

    1978-01-01

    Design and fabrication of supplement test panels that represent key portions of the cylinder are described, as are supporting tests of coupons, sample joints, and stiffening ring elements. The cylindrical shell is a ring-stiffened, open corrugation design that uses T300/5208 graphite-epoxy tape as the basic material for the shell wall and stiffening rings. The test cylinder is designed to withstand bending loads producing the relatively low maximum load intensity in the shell wall of 1,576 N/cm. The resulting shell wall weight, including stiffening rings and fasteners, is 0.0156 kg/m. The shell weight achieved in the graphite-epoxy cylinder represents a weight saving of approximately 23 percent, compared to a comparable aluminum shell. A unique fabrication approach was used in which the cylinder wall was built in three flat segments, which were then wrapped to the cylindrical shape. Such an approach, made possible by the flexibility of the thin corrugated wall in a radial direction, proved to be a simple approach to building the test cylinder. Based on tooling and fabrication methods in this program, the projected costs of a production run of 100 units are reported.

  3. Investigation of a corrugated channel flow with an open source PIV software

    NASA Astrophysics Data System (ADS)

    Sivas, Deniz; Bahadır Olcay, A.; Ahn, Hojin

    2016-03-01

    In this study, the corrugated channel flow was investigated by using an open-source particle image velocimetry (PIV) software. The open-source software called OpenPIV was first verified by using images of an earlier experimental work of a vortex ring formation. The corrugated channel flow images were taken with 200 W power LED light source and a high speed camera and those images were analysed with these spatial and temporal tools of OpenPIV. Laminar, transient and turbulent flow regimes were identified when Reynolds number was below 1100, in between 1100 and 2000 and higher than 2000, respectively. The velocity vectors were found to be about 20% lower than the previous study results. The flow inside the grooves was also investigated with OpenPIV and flow characteristics at the grooves were captured when interrogation window size was lowered. The visualization of the flow was presented for different Reynolds numbers with the relative scale values. As a result of this study, OpenPIV software was determined as promising open source PIV analysis software.

  4. Transmission Loss and Absorption of Corrugated Core Sandwich Panels With Embedded Resonators

    NASA Technical Reports Server (NTRS)

    Allen, Albert R.; Schiller, Noah H.; Zalewski, Bart F.; Rosenthal, Bruce N.

    2014-01-01

    The effect of embedded resonators on the diffuse field sound transmission loss and absorption of composite corrugated core sandwich panels has been evaluated experimentally. Two 1.219 m × 2.438 m panels with embedded resonator arrangements targeting frequencies near 100 Hz were evaluated using non-standard processing of ASTM E90-09 acoustic transmission loss and ASTM C423-09a room absorption test measurements. Each panel is comprised of two composite face sheets sandwiching a corrugated core with a trapezoidal cross section. When inlet openings are introduced in one face sheet, the chambers within the core can be used as embedded acoustic resonators. Changes to the inlet and chamber partition locations allow this type of structure to be tuned for targeted spectrum passive noise control. Because the core chambers are aligned with the plane of the panel, the resonators can be tuned for low frequencies without compromising the sandwich panel construction, which is typically sized to meet static load requirements. Absorption and transmission loss performance improvements attributed to opening the inlets were apparent for some configurations and inconclusive for others.

  5. Finite element modelling of surface acoustic wave device based corrugated microdiaphragms

    NASA Astrophysics Data System (ADS)

    Dissanayake, Don W.; Al-Sarawi, Said; Lu, Tien-Fu; Abbott, Derek

    2009-09-01

    This paper presents modelling and analysis of microdiaphragms that are designed for implantable micropump applications. Microdiaphragms are considered to be a major component of micropumps. A securely operated, electrostatically actuated, fully passive micropump is designed using a novel method, which is based on surface acoustic wave (SAW) devices and wireless transcutaneous radio frequency (RF) communication. The device is capable of extracting the required power from the RF signal itself, like RFID (ID: identification device) tags; hence the need of a battery and active electronics is negated. Moreover, a SAW correlator is used for secure interrogation of the device. As a result, the device responds only to a unique RF signal, which has the same code as was implanted in the SAW correlator. Finite element analysis (FEA) based on code from ANSYS Inc. is carried out to model the microdiaphragm, and a Rayleigh-Ritz method based analytical model is developed to investigate the validity of the FEA results. During the FEA, a three-dimensional model of the diaphragm is developed and various kinds of corrugation profiles are considered for enhancing the device performance. A coupled-field analysis is carried out to model the electrostatics-solid interaction between the corrugated microdiaphragm and the SAW device. In modelling microdiaphragms, selection of appropriate material properties and element types, application of accurate constraints, and selection of suitable mesh parameters are carefully considered.

  6. Mass transport enhancement in redox flow batteries with corrugated fluidic networks

    NASA Astrophysics Data System (ADS)

    Lisboa, Kleber Marques; Marschewski, Julian; Ebejer, Neil; Ruch, Patrick; Cotta, Renato Machado; Michel, Bruno; Poulikakos, Dimos

    2017-08-01

    We propose a facile, novel concept of mass transfer enhancement in flow batteries based on electrolyte guidance in rationally designed corrugated channel systems. The proposed fluidic networks employ periodic throttling of the flow to optimally deflect the electrolytes into the porous electrode, targeting enhancement of the electrolyte-electrode interaction. Theoretical analysis is conducted with channels in the form of trapezoidal waves, confirming and detailing the mass transport enhancement mechanism. In dilute concentration experiments with an alkaline quinone redox chemistry, a scaling of the limiting current with Re0.74 is identified, which compares favourably against the Re0.33 scaling typical of diffusion-limited laminar processes. Experimental IR-corrected polarization curves are presented for high concentration conditions, and a significant performance improvement is observed with the narrowing of the nozzles. The adverse effects of periodic throttling on the pumping power are compared with the benefits in terms of power density, and an improvement of up to 102% in net power density is obtained in comparison with the flow-by case employing straight parallel channels. The proposed novel concept of corrugated fluidic networks comes with facile fabrication and contributes to the improvement of the transport characteristics and overall performance of redox flow battery systems.

  7. Contact-pressure reduction of pyramidal optical probe array on corrugated aluminium/silicon nitride membranes

    NASA Astrophysics Data System (ADS)

    Jang, Jinhee; Oh, Seonghyeon; Hahn, Jae W.

    2017-04-01

    In this study, we develop an optical contact probe array for scanning near-field lithography. We fabricate the optical probes with a pyramidal tip array on an aluminium/silicon nitride composite membrane. Here, we reduce the contact pressure using the corrugations on the silicon nitride membrane and the flattened surface on top of the tip. After fabricating the 5  ×  5 probes in the array, we evaluate the contact pressure using the force–distance curve obtained by an atomic force microscope. The spring constants of the corrugated membranes are 10  ±  0.6 N m‑1. The contact pressure on a flattened 295 nm in-radius is calculated to be approximately 33 MPa for a 300 nm deflection. This value is 22 times smaller than that of a sharp pyramidal tip of 20 nm in-radius on a flat membrane.

  8. Rectified brownian transport in corrugated channels: Fractional brownian motion and Lévy flights.

    PubMed

    Ai, Bao-quan; Shao, Zhi-gang; Zhong, Wei-rong

    2012-11-07

    We study fractional brownian motion and Lévy flights in periodic corrugated channels without any external driving forces. From numerical simulations, we find that both fractional gaussian noise and Lévy-stable noise in asymmetric corrugated channels can break thermodynamical equilibrium and induce directed transport. The rectified mechanisms for fractional brownian motion and Lévy flights are different. The former is caused by non-uniform spectral distribution (low or high frequencies) of fractional gaussian noise, while the latter is due to the nonthermal character (occasional long jumps) of the Lévy-stable noise. For fractional brownian motion, average velocity increases with the Hurst exponent for the persistent case, while for the antipersistent case there exists an optimal value of Hurst exponent at which average velocity takes its maximal value. For Lévy flights, the group velocity decreases monotonically as the Lévy index increases. In addition, for both cases, the optimized periodicity and radius at the bottleneck can facilitate the directed transport. Our results could be implemented in constrained structures with narrow channels and pores where the particles undergo anomalous diffusion.

  9. Simple Correctors for Elimination of High-Order Modes in Corrugated Waveguide Transmission Lines

    PubMed Central

    Kowalski, Elizabeth J.; Shapiro, Michael A.; Temkin, Richard J.

    2014-01-01

    When using overmoded corrugated waveguide transmission lines for high power applications, it is necessary to control the mode content of the system. Ideally, overmoded corrugated transmission lines operate in the fundamental HE11 mode and provide low losses for long distances. Unwanted higher order modes (HOMs), particularly LP11 and HE12, are often excited in the experimental systems due to practical misalignments in the transmission line system. This paper discusses how the unwanted modes propagate along with the fundamental mode in the transmission line system by formulating an equation that relates the center of power offset and angle of propagation of a beam (for the HE11 and LP11 modes) or the waist size and phase front radius of curvature of a beam (for the HE11 and HE12 modes). By introducing two miter bend correctors into the transmission system—miter bends that have slightly angled or ellipsoidal mirrors—the HOMs can be precisely manipulated in the system. This technique can be used to eliminate small quantities of unwanted modes, thereby creating a nearly pure fundamental mode beam with minimal losses. Examples of these applications are calculated and show the theoretical conversion of up to 10% HOM content into the fundamental HE11 mode with minimal losses. PMID:25067859

  10. Simple Expressions for the Design of Linear Tapers in Overmoded Corrugated Waveguides

    DOE PAGES

    Schaub, S. C.; Shapiro, M. A.; Temkin, R. J.

    2015-08-16

    In this paper, simple analytical formulae are presented for the design of linear tapers with very low mode conversion loss in overmoded corrugated waveguides. For tapers from waveguide radius a2 to a1, with a11a2/λ. Here, λ is the wavelength of radiation. The fractional loss of the HE 11 mode in an optimized taper is 0.0293(a2-a1)4/amore » $$2\\atop{1}$$1a$$2\\atop{2}$$. These formulae are accurate when a2≲2a1. Slightly more complex formulae, accurate for a2≤4a1, are also presented in this paper. The loss in an overmoded corrugated linear taper is less than 1 % when a2≤2.12a1 and less than 0.1 % when a2≤1.53a1. The present analytic results have been benchmarked against a rigorous mode matching code and have been found to be very accurate. The results for linear tapers are compared with the analogous expressions for parabolic tapers. Finally, parabolic tapers may provide lower loss, but linear tapers with moderate values of a2/a1 may be attractive because of their simplicity of fabrication.« less

  11. Three-mode coupling of symmetric and antisymmetric Lamb waves in plates with finite corrugations.

    PubMed

    Asfar, Omar; Morvan, Bruno; Izbicki, Jean-Louis

    2015-03-01

    Coupled-mode equations governing the amplitudes of the higher-order symmetric Lamb modes S1 and S2 with the antisymmetric mode A2 in an infinite elastic plate with sinusoidal surface corrugation over a finite length are obtained via multiple-scales analysis. This phenomenon of threemode coupling is observed when the wavenumbers k(s1) and k(s2) of the symmetric modes and k(A2) of the antisymmetric mode satisfy the simultaneous resonance conditions k(s1) - k(A2) = k(w) and k(A2) - k(s2) = k(w), where k(w) is the wavenumber of the sinusoidal corrugation. Near resonance, the coupled amplitude equations are solved exactly as an initial-value problem and it is seen that the modes are transmitted through the grating without reflection. Complete conversion from the symmetric modes into the antisymmetric mode is observed at periodic intervals along the grating when the resonance conditions are exactly satisfied. The effect of detuning away from resonance also shows propagation without reflection with periodic energy exchange. In the latter case, the modes couple without complete conversion. This phenomenon of mode conversion is confirmed by the results of an experiment on an aluminum plate with a triangular grating excited with the S2 symmetric mode at 2.7 MHz.

  12. Tension-induced tunable corrugation in bio-inspired two-phase soft composite materials: mechanisms and implications

    NASA Astrophysics Data System (ADS)

    Elbanna, Ahmed; Chen, Qianli

    We numerically investigate the elastic deformation response of a two-phase bio-inspired soft composite material under externally applied concentric tension using the finite element method. We show that by carefully designing the inclusion pattern it is possible to induce corrugations normal to the direction of stretch. By stacking 1D composite fibers to form 2D membranes, these corrugations collectively lead to the formation of membrane channels with shapes and sizes that are tunable by the level of stretch. Furthermore, we show that by using specific inclusion patterns in laminated plates, it is possible to create pop-ups and troughs enabling the development of complex 3D geometries from planar construction. We have found that the corrugation amplitude increases with the stiffness of inclusion and its eccentricity from the tension axis. We discuss the mechanisms leading to the development of corrugations as well as its different implications. We discuss applications for this design in a variety of fields including tunable band gap formation, surface roughness controllability, auxetic materials and toughness enhancement via programmable evolving geometrical effects..

  13. Enhanced photoluminescence of corrugated Al2O3 film assisted by colloidal CdSe quantum dots

    NASA Astrophysics Data System (ADS)

    Bai, Zhongchen; Hao, Licai; Zhang, Zhengping; Huang, Zhaoling; Qin, Shuijie

    2017-05-01

    We present the enhanced photoluminescence (PL) of a corrugated Al2O3 film enabled by colloidal CdSe quantum dots. The colloidal CdSe quantum dots are fabricated directly on a corrugated Al2O3 substrate using an electrochemical deposition (ECD) method in a microfluidic system. The photoluminescence is excited by using a 150 nm diameter ultraviolet laser spot of a scanning near-field optical microscope. Owing to the electron transfer from the conduction band of the CdSe quantum dots to that of Al2O3, the enhanced photoluminescence effect is observed, which results from the increase in the recombination rate of electrons and holes on the Al2O3 surface and the reduction in the fluorescence of the CdSe quantum dots. A periodically-fluctuating fluorescent spectrum was exhibited because of the periodical wire-like corrugated Al2O3 surface serving as an optical grating. The spectral topographic map around the fluorescence peak from the Al2O3 areas covered with CdSe quantum dots was unique and attributed to the uniform deposition of CdSe QDs on the corrugated Al2O3 surface. We believe that the microfluidic ECD system and the surface enhanced fluorescence method described in this paper have potential applications in forming uniform optoelectronic films of colloidal quantum dots with controllable QD spacing and in boosting the fluorescent efficiency of weak PL devices.

  14. Strength and processing properties of wet-formed hardboards from recycled corrugated containers and commercial hardboard fibers

    Treesearch

    J. F. Hunt; C. B. Vick

    1999-01-01

    Recycled paper fiber recovered from our municipal solid waste stream could potentially be used in structural hardboard products. This study compares strength properties and processing variables of wet-formed high-density hardboard panels made from recycled old corrugated container (OCC) fibers and virgin hardboard fibers using continuous pressure during drying. The...

  15. FE analysis of creep and hygroexpansion response of a corrugated fiberboard to a moisture flow : a transient nonlinear analysis

    Treesearch

    Adeeb A. Rahman; Thomas J. Urbanik; Mustafa Mahamid

    2006-01-01

    This paper presents a model using finite element method to study the response of a typical commercial corrugated fiberboard due to an induced moisture function at one side of the fiberboard. The model predicts how the moisture diffusion will permeate through the fiberboard’s layers(medium and liners) providing information on moisture content at any given point...

  16. Enhanced photoluminescence of corrugated Al2O3 film assisted by colloidal CdSe quantum dots.

    PubMed

    Bai, Zhongchen; Hao, Licai; Zhang, Zhengping; Huang, Zhaoling; Qin, Shuijie

    2017-05-19

    We present the enhanced photoluminescence (PL) of a corrugated Al2O3 film enabled by colloidal CdSe quantum dots. The colloidal CdSe quantum dots are fabricated directly on a corrugated Al2O3 substrate using an electrochemical deposition (ECD) method in a microfluidic system. The photoluminescence is excited by using a 150 nm diameter ultraviolet laser spot of a scanning near-field optical microscope. Owing to the electron transfer from the conduction band of the CdSe quantum dots to that of Al2O3, the enhanced photoluminescence effect is observed, which results from the increase in the recombination rate of electrons and holes on the Al2O3 surface and the reduction in the fluorescence of the CdSe quantum dots. A periodically-fluctuating fluorescent spectrum was exhibited because of the periodical wire-like corrugated Al2O3 surface serving as an optical grating. The spectral topographic map around the fluorescence peak from the Al2O3 areas covered with CdSe quantum dots was unique and attributed to the uniform deposition of CdSe QDs on the corrugated Al2O3 surface. We believe that the microfluidic ECD system and the surface enhanced fluorescence method described in this paper have potential applications in forming uniform optoelectronic films of colloidal quantum dots with controllable QD spacing and in boosting the fluorescent efficiency of weak PL devices.

  17. Simulation of turbulent heat transfer characteristics in a corrugated tube with five-channel twisted tape inserts

    NASA Astrophysics Data System (ADS)

    Promthaisong, Pitak; Jedsadaratanachai, Withada; Chuwattanakul, Varesa; Eiamsa-ard, Smith

    2017-08-01

    The article presents a numerical analysis of turbulent periodic flow and heat transfer characteristics in a five-start spiral corrugated tube combined with five-channel twisted tape. Influences of the five-channel twisted tape with tape width ratio, w/D=0.10, 0.20, 0.30, 0.40 and 0.44 at constant the twisted length ratio, y/D=2.0 were described. The results were reported in term of flow structure, temperature distribution, TKE field, local Nusselt number distribution on the wall, Nusselt number ratio, friction factor ratio and thermal enhancement factor. The five-start spiral corrugated tube combined with five-channel twisted tape showed a main swirl flow and secondary swirl flow along the tube due to the induction of the spiral groove while the smooth circular tube appeared the straight only and the five-start spiral corrugated tube with the five-channel twisted tape at w/D=0.44 appeared the main swirl flow only. The swirl flow help to increase fluid mixing and increase in heat transfer rate over the smooth circular tube. The increase in the w/D lead to the rise of Nusselt number and friction factor. The result showed that the optimum thermal enhancement factor of about 1.16was found at the five-start spiral corrugated tube without the five-channel twisted tape and at w/D=0.44.

  18. Atomic scale study of corrugating and anticorrugating states on the bare Si(1 0 0) surface

    NASA Astrophysics Data System (ADS)

    Yengui, Mayssa; Pinto, Henry P.; Leszczynski, Jerzy; Riedel, Damien

    2015-02-01

    In this article, we study the origin of the corrugating and anticorrugating states through the electronic properties of the Si(1 0 0) surface via a low-temperature (9 K) scanning tunneling microscope (STM). Our study is based on the analysis of the STM topographies corrugation variations when related to the shift of the local density of states (LDOS) maximum in the [1 \\bar{{1}} 0] direction. Our experimental results are correlated with numerical simulations using the density-functional theory with hybrid Heyd-Scuseria-Ernzerhof (HSE06) functional to simulate the STM topographies, the projected density of states variations at different depths in the silicon surface as well as the three dimensional partial charge density distributions in real-space. This work reveals that the Si(1 0 0) surface exhibits two anticorrugating states at +0.8 and +2.8 V that are associated with a phase shift of the LDOS maximum in the unoccupied states STM topographies. By comparing the calculated data with our experimental results, we have been able to identify the link between the variations of the STM topographies corrugation and the shift of the LDOS maximum observed experimentally. Each surface voltage at which the STM topographies corrugation drops is defined as anticorrugating states. In addition, we have evidenced a sharp jump in the tunnel current when the second LDOS maximum shift is probed, whose origin is discussed and associated with the presence of Van Hove singularities.

  19. 77 FR 67400 - RG Steel Wheeling, LLC, a Division of RG Steel, LLC, Doing Business as Wheeling Corrugating...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-09

    ... Employment and Training Administration RG Steel Wheeling, LLC, a Division of RG Steel, LLC, Doing Business as..., 2012, applicable to workers of RG Steel Wheeling, LLC, a division of RG Steel, LLC, doing business as... RG Steel, LLC, doing business as Wheeling Corrugating Company, Beech Bottom, West Virginia,...

  20. Pressure drop of slush nitrogen flow in converging-diverging pipes and corrugated pipes

    NASA Astrophysics Data System (ADS)

    Ohira, Katsuhide; Okuyama, Jun; Nakagomi, Kei; Takahashi, Koichi

    2012-12-01

    Cryogenic slush fluids such as slush hydrogen and slush nitrogen are solid-liquid, two-phase fluids. As a functional thermal fluid, there are high expectations for use of slush fluids in various applications such as fuels for spacecraft engines, clean-energy fuels to improve the efficiency of transportation and storage, and as refrigerants for high-temperature superconducting equipment. Experimental flow tests were performed using slush nitrogen to elucidate pressure-drop characteristics of converging-diverging (C-D) pipes and corrugated pipes. In experimental results regarding pressure drop in two different types of C-D Pipes, i.e., a long-throated pipe and a short-throated pipe, each having an inner diameter of 15 mm, pressure drop for slush nitrogen in the long-throated pipe at a flow velocity of over 1.3 m/s increased by a maximum of 50-60% as compared to that for liquid nitrogen, while the increase was about 4 times as compared to slush nitrogen in the short-throated pipe. At a flow velocity of over 1.5 m/s in the short-throated pipe, pressure drop reduction became apparent, and it was confirmed that the decrease in pressure drop compared to liquid nitrogen was a maximum of 40-50%. In the case of two different types of corrugated pipes with an inner diameter of either 12 mm or 15 mm, a pressure-drop reduction was confirmed at a flow velocity of over 2 m/s, and reached a maximum value of 37% at 30 wt.% compared to liquid nitrogen. The greater the solid fractions, the smaller the pipe friction factor became, and the pipe friction factor at the same solid fraction showed a constant value regardless of the Reynolds number. From the observation of the solid particles' behavior using a high-speed video camera and the PIV method, the pressure-drop reduction mechanisms for both C-D and corrugated pipes were demonstrated.

  1. Growth of InP directly on Si by corrugated epitaxial lateral overgrowth

    NASA Astrophysics Data System (ADS)

    Metaferia, Wondwosen; Kataria, Himanshu; Sun, Yan-Ting; Lourdudoss, Sebastian

    2015-02-01

    In an attempt to achieve an InP-Si heterointerface, a new and generic method, the corrugated epitaxial lateral overgrowth (CELOG) technique in a hydride vapor phase epitaxy reactor, was studied. An InP seed layer on Si (0 0 1) was patterned into closely spaced etched mesa stripes, revealing the Si surface in between them. The surface with the mesa stripes resembles a corrugated surface. The top and sidewalls of the mesa stripes were then covered by a SiO2 mask after which the line openings on top of the mesa stripes were patterned. Growth of InP was performed on this corrugated surface. It is shown that growth of InP emerges selectively from the openings and not on the exposed silicon surface, but gradually spreads laterally to create a direct interface with the silicon, hence the name CELOG. We study the growth behavior using growth parameters. The lateral growth is bounded by high index boundary planes of {3 3 1} and {2 1 1}. The atomic arrangement of these planes, crystallographic orientation dependent dopant incorporation and gas phase supersaturation are shown to affect the extent of lateral growth. A lateral to vertical growth rate ratio as large as 3.6 is achieved. X-ray diffraction studies confirm substantial crystalline quality improvement of the CELOG InP compared to the InP seed layer. Transmission electron microscopy studies reveal the formation of a direct InP-Si heterointerface by CELOG without threading dislocations. While CELOG is shown to avoid dislocations that could arise due to the large lattice mismatch (8%) between InP and Si, staking faults could be seen in the layer. These are probably created by the surface roughness of the Si surface or SiO2 mask which in turn would have been a consequence of the initial process treatments. The direct InP-Si heterointerface can find applications in high efficiency and cost-effective Si based III-V semiconductor multijunction solar cells and optoelectronics integration.

  2. Plastic casting resin poisoning

    MedlinePlus

    Epoxy poisoning; Resin poisoning ... Epoxy and resin can be poisonous if they are swallowed or their fumes are breathed in. ... Plastic casting resins are found in various plastic casting resin products.

  3. Plastic encapsulated parts

    SciTech Connect

    Castillo, T.

    1994-10-01

    Plastic semiconductor packages were characterized as possible alternatives for canned devices, which are susceptible to internal shorts caused by conductive particles. Highly accelerated stress testing (HAST) as well as electrical and mechanical testing were conducted on plastic technology devices.

  4. Ear Plastic Surgery

    MedlinePlus

    ... ENTCareers Marketplace Find an ENT Doctor Near You Ear Plastic Surgery Ear Plastic Surgery Patient Health Information ... they may improve appearance and self-confidence. Can Ear Deformities Be Corrected? Formation of the ear during ...

  5. Improvement of Progressive Damage Model to Predicting Crashworthy Composite Corrugated Plate

    NASA Astrophysics Data System (ADS)

    Ren, Yiru; Jiang, Hongyong; Ji, Wenyuan; Zhang, Hanyu; Xiang, Jinwu; Yuan, Fuh-Gwo

    2017-05-01

    To predict the crashworthy composite corrugated plate, different single and stacked shell models are evaluated and compared, and a stacked shell progressive damage model combined with continuum damage mechanics is proposed and investigated. To simulate and predict the failure behavior, both of the intra- and inter- laminar failure behavior are considered. The tiebreak contact method, 1D spot weld element and cohesive element are adopted in stacked shell model, and a surface-based cohesive behavior is used to capture delamination in the proposed model. The impact load and failure behavior of purposed and conventional progressive damage models are demonstrated. Results show that the single shell could simulate the impact load curve without the delamination simulation ability. The general stacked shell model could simulate the interlaminar failure behavior. The improved stacked shell model with continuum damage mechanics and cohesive element not only agree well with the impact load, but also capture the fiber, matrix debonding, and interlaminar failure of composite structure.

  6. Using pipe with corrugated walls for a subterahertz free electron laser

    DOE PAGES

    Stupakov, Gennady

    2015-03-18

    A metallic pipe with corrugated walls supports propagation of a high-frequency mode that is in resonance with a relativistic beam propagating along the axis of the pipe. This mode can be excited by a beam whose length is a fraction of the wavelength. In this paper, we study another option of excitation of the resonant mode—via the mechanism of the free electron laser instability. This mechanism works if the bunch length is much longer than the wavelength of the radiation and, hence, does not require bunch compression. As a result, it provides an alternative to excitation by short bunches thatmore » can be realized with relatively low energy and low peak-current electron beams.« less

  7. High second-order nonlinear response of platinum nanoflowers: the role of surface corrugation.

    PubMed

    Ngo, Hoang Minh; Lai, Ngoc Diep; Ledoux-Rak, Isabelle

    2016-02-14

    Platinum nanoflowers (PtNFs) were elaborated using the seed-mediated growth technique applied to monodisperse platinum nanoparticles (∼3.0 nm) synthesized by the chemical reduction method. The X-ray diffraction pattern confirmed the formation of face-centered-cubic platinum nanocrystals. We report the Harmonic Light Scattering (HLS) properties of PtNFs for six different diameters (∼7.0; 8.0; 10.0; 14.0; 20.0 and 31.0 nm). From these HLS data we infer, for the first time, large hyperpolarizability β values of PtNFs. These very high β values of PtNFs are assigned mainly to highly corrugated surfaces for nanoparticles with irregular shapes.

  8. Energy shift of collective electron excitations in highly corrugated graphitic nanostructures: Experimental and theoretical investigation

    SciTech Connect

    Sedelnikova, O. V. Bulusheva, L. G.; Okotrub, A. V.; Asanov, I. P.; Yushina, I. V.

    2014-04-21

    Effect of corrugation of hexagonal carbon network on the collective electron excitations has been studied using optical absorption and X-ray photoelectron spectroscopy in conjunction with density functional theory calculations. Onion-like carbon (OLC) was taken as a material, where graphitic mantle enveloping agglomerates of multi-shell fullerenes is strongly curved. Experiments showed that positions of π and π + σ plasmon modes as well as π → π* absorption peak are substantially redshifted for OLC as compared with those of highly ordered pyrolytic graphite and thermally exfoliated graphite consisted of planar sheets. This effect was reproduced in behavior of dielectric functions of rippled graphite models calculated within the random phase approximation. We conclude that the energy of electron excitations in graphitic materials could be precisely tuned by a simple bending of hexagonal network without change of topology. Moreover, our investigation suggests that in such materials optical exciton can transfer energy to plasmon non-radiatively.

  9. Entropically induced asymmetric passage times of charged tracers across corrugated channels.

    PubMed

    Malgaretti, Paolo; Pagonabarraga, Ignacio; Rubi, J Miguel

    2016-01-21

    We analyze the diffusion of charged and neutral tracers suspended in an electrolyte embedded in a channel of varying cross section. Making use of systematic approximations, the diffusion equation governing the motion of tracers is mapped into an effective 1D equation describing the dynamics along the longitudinal axis of the channel where its varying-section is encoded as an effective entropic potential. This simplified approach allows us to characterize tracer diffusion under generic confinement by measuring their mean first passage time (MFPT). In particular, we show that the interplay between geometrical confinement and electrostatic interactions strongly affect the MFTP of tracers across corrugated channels hence leading to alternative means to control tracers translocation across charged pores. Finally, our results show that the MFPTs of a charged tracer in opposite directions along an asymmetric channel may differ We expect our results to be relevant for biological as well synthetic devices whose dynamics is controlled by the detection of diluted tracers.

  10. Experimental investigation of the dispersion of Scholte-Stoneley waves on a periodically corrugated surface

    NASA Astrophysics Data System (ADS)

    Liu, Jingfei; Declercq, Nico F.

    2016-12-01

    The dispersion of the phase velocities of the Scholte-Stoneley waves on a periodically corrugated interface is experimentally investigated and presented. The Scholte-Stoneley waves are generated through diffraction of the incident bulk longitudinal waves in water on a solid-fluid (brass-water) interface with one-dimensional grooves. The diffractions resulting from both the incident longitudinal waves and the generated Scholte-Stoneley waves are experimentally detected in a polar scan. The extracted velocity-frequency curves first confirm that the incident bulk wave is not dispersive and further show that the Scholte-Stoneley wave generated on the periodic interface is also not dispersive, although the velocity-frequency curves have oscillatory features.

  11. Theory of the corrugation instability of a piston-driven shock wave.

    PubMed

    Bates, J W

    2015-01-01

    We analyze the two-dimensional stability of a shock wave driven by a steadily moving corrugated piston in an inviscid fluid with an arbitrary equation of state. For h≤-1 or h>h(c), where h is the D'yakov parameter and h(c) is the Kontorovich limit, we find that small perturbations on the shock front are unstable and grow--at first quadratically and later linearly--with time. Such instabilities are associated with nonequilibrium fluid states and imply a nonunique solution to the hydrodynamic equations. The above criteria are consistent with instability limits observed in shock-tube experiments involving ionizing and dissociating gases and may have important implications for driven shocks in laser-fusion, astrophysical, and/or detonation studies.

  12. Entropically induced asymmetric passage times of charged tracers across corrugated channels

    SciTech Connect

    Malgaretti, Paolo; Pagonabarraga, Ignacio; Miguel Rubi, J.

    2016-01-21

    We analyze the diffusion of charged and neutral tracers suspended in an electrolyte embedded in a channel of varying cross section. Making use of systematic approximations, the diffusion equation governing the motion of tracers is mapped into an effective 1D equation describing the dynamics along the longitudinal axis of the channel where its varying-section is encoded as an effective entropic potential. This simplified approach allows us to characterize tracer diffusion under generic confinement by measuring their mean first passage time (MFPT). In particular, we show that the interplay between geometrical confinement and electrostatic interactions strongly affect the MFTP of tracers across corrugated channels hence leading to alternative means to control tracers translocation across charged pores. Finally, our results show that the MFPTs of a charged tracer in opposite directions along an asymmetric channel may differ We expect our results to be relevant for biological as well synthetic devices whose dynamics is controlled by the detection of diluted tracers.

  13. Dynamical back-action at 5.5 GHz in a corrugated optomechanical beam

    SciTech Connect

    Navarro-Urrios, D.; Gomis-Bresco, J.; Alzina, F.; El-Jallal, S.; Oudich, M.; Pennec, Y.; Djafari-Rouhani, B.; Pitanti, A.; Capuj, N.; Tredicucci, A.; Griol, A.; Martínez, A.; Sotomayor Torres, C. M.

    2014-12-15

    We report on the optomechanical properties of a breathing mechanical mode oscillating at 5.5 GHz in a 1D corrugated Si nanobeam. This mode has an experimental single-particle optomechanical coupling rate of |g{sub o,OM}| = 1.8 MHz (|g{sub o,OM}|/2π = 0.3 MHz) and shows strong dynamical back-action effects at room temperature. The geometrical flexibility of the unit-cell would lend itself to further engineering of the cavity region to localize the mode within the full phononic band-gap present at 4 GHz while keeping high g{sub o,OM} values. This would lead to longer lifetimes at cryogenic temperatures, due to the suppression of acoustic leakage.

  14. Improved method for computing of light-matter interaction in multilayer corrugated structures.

    PubMed

    Korovin, Alexander V

    2008-02-01

    An improved method for the calculation of light-matter interaction that appears with the light propagation through multilayer periodically corrugated structures consisting of any dielectric or absorptive media is reported. The method is based on the differential formalism for a system of Maxwell's equations when the boundary conditions are simplified by the introduction of a curvilinear nonorthogonal coordinate system. The solution for electromagnetic fields was written in the form of the superposition of partial plane waves. The obtained method essentially reduces computation time and increases accuracy compared with the Chandezon method. For a numerical demonstration of the proposed method, calculation of long-range surface plasmon polaritons was performed. The presented method can be enhanced for calculations of light propagation through thin absorptive films with various periodic profiles at both film interfaces.

  15. Radial Corrugations of Multi-Walled Carbon Nanotubes Driven by Inter-Wall Nonbonding Interactions.

    PubMed

    Huang, Xu; Liang, Wentao; Zhang, Sulin

    2011-12-01

    We perform large-scale quasi-continuum simulations to determine the stable cross-sectional configurations of free-standing multi-walled carbon nanotubes (MWCNTs). We show that at an inter-wall spacing larger than the equilibrium distance set by the inter-wall van der Waals (vdW) interactions, the initial circular cross-sections of the MWCNTs are transformed into symmetric polygonal shapes or asymmetric water-drop-like shapes. Our simulations also show that removing several innermost walls causes even more drastic cross-sectional polygonization of the MWCNTs. The predicted cross-sectional configurations agree with prior experimental observations. We attribute the radial corrugations to the compressive stresses induced by the excessive inter-wall vdW energy release of the MWCNTs. The stable cross-sectional configurations provide fundamental guidance to the design of single MWCNT-based devices and shed lights on the mechanical control of electrical properties.

  16. Theory of the corrugation instability of a piston-driven shock wave

    NASA Astrophysics Data System (ADS)

    Bates, J. W.

    2015-01-01

    We analyze the two-dimensional stability of a shock wave driven by a steadily moving corrugated piston in an inviscid fluid with an arbitrary equation of state. For h ≤-1 or h >hc , where h is the D'yakov parameter and hc is the Kontorovich limit, we find that small perturbations on the shock front are unstable and grow—at first quadratically and later linearly—with time. Such instabilities are associated with nonequilibrium fluid states and imply a nonunique solution to the hydrodynamic equations. The above criteria are consistent with instability limits observed in shock-tube experiments involving ionizing and dissociating gases and may have important implications for driven shocks in laser-fusion, astrophysical, and/or detonation studies.

  17. Highly tapered pentagonal bipyramidal Au microcrystals with high index faceted corrugation: Synthesis and optical properties

    PubMed Central

    Mettela, Gangaiah; Boya, Radha; Singh, Danveer; Kumar, G. V. Pavan; Kulkarni, G. U.

    2013-01-01

    Focusing light at sub-wavelength region opens up interesting applications in optical sensing and imaging beyond the diffraction limit. In the past, tapered Au wires with carved gratings have been employed to achieve nanofocusing. The fabrication process however, is expensive and the obtained wires are polycrystalline with high surface roughness. A chemical synthetic method overcoming these hurdles should be an attractive alternative. Here, we report a method to chemically synthesize Au microcrystals (~10 μm) bearing pentagonal bipyramidal morphology with surface corrugations assignable to high index planes. The method is a single step solid state synthesis at a temperature amenable to common substrates. The microcrystals are tapered at both ends forming sharp tips (~55 nm). Individual microcrystals have been used as pick and probe SERS substrates for a dye embedded in a polymer matrix. The unique geometry of the microcrystal also enables light propagation across its length.

  18. Energy shift of collective electron excitations in highly corrugated graphitic nanostructures: Experimental and theoretical investigation

    NASA Astrophysics Data System (ADS)

    Sedelnikova, O. V.; Bulusheva, L. G.; Asanov, I. P.; Yushina, I. V.; Okotrub, A. V.

    2014-04-01

    Effect of corrugation of hexagonal carbon network on the collective electron excitations has been studied using optical absorption and X-ray photoelectron spectroscopy in conjunction with density functional theory calculations. Onion-like carbon (OLC) was taken as a material, where graphitic mantle enveloping agglomerates of multi-shell fullerenes is strongly curved. Experiments showed that positions of π and π + σ plasmon modes as well as π → π* absorption peak are substantially redshifted for OLC as compared with those of highly ordered pyrolytic graphite and thermally exfoliated graphite consisted of planar sheets. This effect was reproduced in behavior of dielectric functions of rippled graphite models calculated within the random phase approximation. We conclude that the energy of electron excitations in graphitic materials could be precisely tuned by a simple bending of hexagonal network without change of topology. Moreover, our investigation suggests that in such materials optical exciton can transfer energy to plasmon non-radiatively.

  19. Comparison of finite source and plane wave scattering from corrugated surfaces

    NASA Technical Reports Server (NTRS)

    Levine, D. M.

    1977-01-01

    The choice of a plane wave to represent incident radiation in the analysis of scatter from corrugated surfaces was examined. The physical optics solution obtained for the scattered fields due to an incident plane wave was compared with the solution obtained when the incident radiation is produced by a source of finite size and finite distance from the surface. The two solutions are equivalent if the observer is in the far field of the scatterer and the distance from observer to scatterer is large compared to the radius of curvature at the scatter points, condition not easily satisfied with extended scatterers such as rough surfaces. In general, the two solutions have essential differences such as in the location of the scatter points and the dependence of the scattered fields on the surface properties. The implication of these differences to the definition of a meaningful radar cross section was examined.

  20. Mastered dispersion of material resonators: Broad corrugated waveguides working under the Littrow regime

    NASA Astrophysics Data System (ADS)

    Benisty, H.; Piskunov, N.

    2013-04-01

    An anomalous dispersion for modes of a material resonator is highly desired to form frequency combs. A resonator free-spectral-range (FSR) controlled by shape so as to increase with frequency ω/2π compensates the normal index dispersion ∂n/∂ω > 0, producing evenly spaced resonances. Only special shapes achieve this scope. We show here that broad periodic corrugated waveguides working at Littrow regime feature such an increasing trend ∂FSR/∂ω > 0. We outline experimentally this trend on silicon-on-insulator devices designed for 45° Littrow operation. We predict dispersion-free silicon-based designs across the 1.4-4.0 μm mid-infrared range.

  1. Euler buckling, membrane corrugation and pore formation induced by antimicrobial peptide

    NASA Astrophysics Data System (ADS)

    Golubovic, Leonardo; Gao, Lianghui; Chen, Licui; Jia, Nana; Fang, Weihai

    2014-03-01

    Antimicrobial peptides serve as defense weapons against bacteria. They are secreted by organisms of plants and animals and have a wide variety in composition and structure. In this study, we theoretically explore the effects of the antimicrobial peptides on the lipid bilayer membrane by using analytic arguments and the coarse grained dissipative particle dynamics simulations. We study peptide/lipid membrane complexes by considering peptides with various structure, hydrophobicity and peptide/lipid interaction strength. The role of lipid/water interaction is also discussed. We discuss a rich variety of membrane morphological changes induced by peptides, such as pore formation, membrane corrugation and Euler buckling. Such buckled membrane states have been indeed seen in a number of experiments with bacteria affected by peptide, yet this is the first theoretical study addressing these phenomena more deeply.

  2. #PlasticSurgery.

    PubMed

    Branford, Olivier A; Kamali, Parisa; Rohrich, Rod J; Song, David H; Mallucci, Patrick; Liu, Daniel Z; Lang, Dustin; Sun, Kristi; Stubican, Miran; Lin, Samuel J

    2016-12-01

    Social media use is growing inexorably, and there is public appetite for evidence-based information. Little is known about engagement by plastic surgeons with social media. The aim of this study was to examine posting about plastic surgery on Twitter, to best inform how board-certified plastic surgeons could use the hashtag #PlasticSurgery as a tool to educate patients and the public. A prospective analysis of 2880 "tweets" containing the words "plastic surgery" was performed. The following were assessed: identity of author, use of the hashtag #PlasticSurgery, subject matter, whether link to study was provided, and whether posts by surgeons were self-promotional or educational. Social media posting about plastic surgery is dominated by the public, accounting for 70.6 percent of posts versus only 6.0 percent by plastic surgeons. Only 5.4 percent of all tweets contained the hashtag #PlasticSurgery, although almost half of those that did were by plastic surgeons. Of these, 61.3 percent of posts by plastic surgeons were about aesthetic surgery; additional posts were about basic science, patient safety, and reconstruction (13.9, 4.0, and 2.3 percent, respectively). Eighteen scientific articles were referenced, with a link to the Journal site posted in two tweets. Of posts by plastic surgeons, 37.0 percent were self-promotional. The American Society of Plastic Surgeons and its Journal have recognized that social media may be used to educate and engage. Board-certified plastic surgeons have a great opportunity to promote evidence-based plastic practice by means of #PlasticSurgery in the interests of supporting patients and the profession.

  3. High second-order nonlinear response of platinum nanoflowers: the role of surface corrugation

    NASA Astrophysics Data System (ADS)

    Ngo, Hoang Minh; Lai, Ngoc Diep; Ledoux-Rak, Isabelle

    2016-02-01

    Platinum nanoflowers (PtNFs) were elaborated using the seed-mediated growth technique applied to monodisperse platinum nanoparticles (~3.0 nm) synthesized by the chemical reduction method. The X-ray diffraction pattern confirmed the formation of face-centered-cubic platinum nanocrystals. We report the Harmonic Light Scattering (HLS) properties of PtNFs for six different diameters (~7.0 8.0; 10.0; 14.0; 20.0 and 31.0 nm). From these HLS data we infer, for the first time, large hyperpolarizability β values of PtNFs. These very high β values of PtNFs are assigned mainly to highly corrugated surfaces for nanoparticles with irregular shapes.Platinum nanoflowers (PtNFs) were elaborated using the seed-mediated growth technique applied to monodisperse platinum nanoparticles (~3.0 nm) synthesized by the chemical reduction method. The X-ray diffraction pattern confirmed the formation of face-centered-cubic platinum nanocrystals. We report the Harmonic Light Scattering (HLS) properties of PtNFs for six different diameters (~7.0 8.0; 10.0; 14.0; 20.0 and 31.0 nm). From these HLS data we infer, for the first time, large hyperpolarizability β values of PtNFs. These very high β values of PtNFs are assigned mainly to highly corrugated surfaces for nanoparticles with irregular shapes. Electronic supplementary information (ESI) available: The recalculated β and β' values inferred from data by Galletto et al.15 in AuNSs using their reported β values per nanoparticle corrected. See DOI: 10.1039/c5nr07571h

  4. Simple Expressions for the Design of Linear Tapers in Overmoded Corrugated Waveguides

    SciTech Connect

    Schaub, S. C.; Shapiro, M. A.; Temkin, R. J.

    2015-08-16

    In this paper, simple analytical formulae are presented for the design of linear tapers with very low mode conversion loss in overmoded corrugated waveguides. For tapers from waveguide radius a2 to a1, with a11a2/λ. Here, λ is the wavelength of radiation. The fractional loss of the HE 11 mode in an optimized taper is 0.0293(a2-a1)4/a$2\\atop{1}$1a$2\\atop{2}$. These formulae are accurate when a2≲2a1. Slightly more complex formulae, accurate for a2≤4a1, are also presented in this paper. The loss in an overmoded corrugated linear taper is less than 1 % when a2≤2.12a1 and less than 0.1 % when a2≤1.53a1. The present analytic results have been benchmarked against a rigorous mode matching code and have been found to be very accurate. The results for linear tapers are compared with the analogous expressions for parabolic tapers. Finally, parabolic tapers may provide lower loss, but linear tapers with moderate values of a2/a1 may be attractive because of their simplicity of fabrication.

  5. Tomorrow's Plastic World

    ERIC Educational Resources Information Center

    Macdonald, Averil

    2005-01-01

    Far from being just cheap packaging materials, plastics may be the materials of tomorrow. Plastic can conduct electricity, and this opens up a host of high-tech possibilities in the home and in energy generation. These possibilities are discussed here along with how plastic can be recycled and perhaps even grown.

  6. Plastics in Building.

    ERIC Educational Resources Information Center

    Skeist, Irving, Ed.

    The evaluation and use of plastics in the construction industry are explained. The contributors offer extensive, timely, and thoroughly researched data on the chemistry, properties, functions, engineering behavior, and specific applications of plastics to building requirements. The major subjects discussed in depth are--(1) the role of plastics in…

  7. Processing of plastics

    PubMed Central

    Spaak, Albert

    1975-01-01

    An overview is given of the processing of plastic materials from the handling of polymers in the pellet and powder form to manufacturing of a plastic fabricated product. Various types of equipment used and melt processing ranges of various polymer formulations to make the myriad of plastic products that are commercially available are discussed. PMID:1175556

  8. Tomorrow's Plastic World

    ERIC Educational Resources Information Center

    Macdonald, Averil

    2005-01-01

    Far from being just cheap packaging materials, plastics may be the materials of tomorrow. Plastic can conduct electricity, and this opens up a host of high-tech possibilities in the home and in energy generation. These possibilities are discussed here along with how plastic can be recycled and perhaps even grown.

  9. Plastics in Building.

    ERIC Educational Resources Information Center

    Skeist, Irving, Ed.

    The evaluation and use of plastics in the construction industry are explained. The contributors offer extensive, timely, and thoroughly researched data on the chemistry, properties, functions, engineering behavior, and specific applications of plastics to building requirements. The major subjects discussed in depth are--(1) the role of plastics in…

  10. Surface Plasmon-Polariton Mediated Red Emission from Organic Light-Emitting Devices Based on Metallic Electrodes Integrated with Dual-Periodic Corrugation

    PubMed Central

    Bi, Yan-Gang; Feng, Jing; Liu, Yu-Shan; Li, Yun-Fei; Chen, Yang; Zhang, Xu-Lin; Han, Xiao-Chi; Sun, Hong-Bo

    2014-01-01

    We demonstrate an effective approach to realize excitation and outcoupling of the SPP modes associated with both cathode/organic and anode/organic interfaces in OLEDs by integrating dual-periodic corrugation. The dual-periodic corrugation consists of two set gratings with different periods. The light trapped in the SPP modes associated with both top and bottom electrode/organic interfaces are efficiently extracted from the OLEDs by adjusting appropriate periods of two set corrugations, and a 29% enhancement in the current efficiency has been obtained. PMID:25407776

  11. Biodegradability of plastics.

    PubMed

    Tokiwa, Yutaka; Calabia, Buenaventurada P; Ugwu, Charles U; Aiba, Seiichi

    2009-08-26

    Plastic is a broad name given to different polymers with high molecular weight, which can be degraded by various processes. However, considering their abundance in the environment and their specificity in attacking plastics, biodegradation of plastics by microorganisms and enzymes seems to be the most effective process. When plastics are used as substrates for microorganisms, evaluation of their biodegradability should not only be based on their chemical structure, but also on their physical properties (melting point, glass transition temperature, crystallinity, storage modulus etc.). In this review, microbial and enzymatic biodegradation of plastics and some factors that affect their biodegradability are discussed.

  12. Biodegradability of Plastics

    PubMed Central

    Tokiwa, Yutaka; Calabia, Buenaventurada P.; Ugwu, Charles U.; Aiba, Seiichi

    2009-01-01

    Plastic is a broad name given to different polymers with high molecular weight, which can be degraded by various processes. However, considering their abundance in the environment and their specificity in attacking plastics, biodegradation of plastics by microorganisms and enzymes seems to be the most effective process. When plastics are used as substrates for microorganisms, evaluation of their biodegradability should not only be based on their chemical structure, but also on their physical properties (melting point, glass transition temperature, crystallinity, storage modulus etc.). In this review, microbial and enzymatic biodegradation of plastics and some factors that affect their biodegradability are discussed. PMID:19865515

  13. An account of the longitudinal mucosal corrugations of the human tracheo-bronchial tree, with observations on those of some animals.

    PubMed Central

    Monkhouse, W S; Whimster, W F

    1976-01-01

    A description is given of the distribution of the longitudinal mucosal corrugations in the human tracheo-bronchial tree. It has been shown that they are made up of elastic tissue in a collagen matrix, and that the elastic fibres continue into the smallest bronchioles beyond where the corrugations are no longer visible. An examination has also been made of the tracheo-bronchial trees of the hen, rat, raccoon, pig, sheep, llama and tiger. Corrugations are present in all these animals, except the hen and the raccoon, and they have been compared and contrasted with the condition in Man. The functional significance of these corrugations remains unknown, but, they could be important in equalizing tension in the tracheo-bronchial tree during inspiration, as well as in providing elastic recoil during expiration. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 11 Fig. 12 PMID:1010796

  14. How Plastics Work

    NASA Astrophysics Data System (ADS)

    Bloomfield, Louis

    2013-03-01

    We encounter plastics every day, but despite their widespread use, amazing range of properties, and basic scientific underpinnings, most physicists--like most people--know relatively little about plastics. In contrast to hard crystalline and amorphous solids (e.g., metals, salts, ceramics, and glasses), we take plastics for granted, select them carelessly, and examine them more closely only on a need-to-know basis. By ignoring plastics until we need them, however, we risk not knowing what we don't know and using the wrong ones. To repurpose a familiar advertisement, ``there's a plastic for that.'' This talk will review some of the basic physics and science of plastics. It will examine the roles of temperature, order, intermolecular forces, entanglements, and linkages in plastics, and how those issues affect the properties of a given plastic. We'll stop along the way to recognize a few of the more familiar plastics, natural and synthetic, and explain some of their mechanical, chemical, and optical properties. The talk will conclude by explaining the remarkable properties of a plastic that has been largely misunderstood since its discovery 70 years ago: Silly Putty.

  15. Influence of pH upon surface-enhanced enzyme-catalyzed luminol chemiluminescence at vicinity of nanoscale-corrugated gold and silver films.

    PubMed

    Ou, Meigui; Lu, Guowei; Shen, Hong; Descamps, Armel; Marquette, Christophe André; Blum, Loïc Jacques; Roux, Stéphane; Tillement, Olivier; Cheng, Bolin; Perriat, Pascal

    2008-01-01

    Au and Ag biochips were fabricated to investigate the influence of pH upon the chemiluminescence (CL) of luminol at vicinity of surface-adsorbed peroxidase. A nanoscaled-corrugation of the metal induces an enhancement of the luminol CL which is maximal in the pH range favoring peroxidase catalysis and greater for gold than for silver. This is the proof that, in the CL process, the reactions involving peroxidase are surface-enhanced near corrugated surfaces.

  16. Experimental Demonstration of Longitudinal Beam Phase-Space Linearizer in a Free-Electron Laser Facility by Corrugated Structures

    NASA Astrophysics Data System (ADS)

    Deng, Haixiao; Zhang, Meng; Feng, Chao; Zhang, Tong; Wang, Xingtao; Lan, Taihe; Feng, Lie; Zhang, Wenyan; Liu, Xiaoqing; Yao, Haifeng; Shen, Lei; Li, Bin; Zhang, Junqiang; Li, Xuan; Fang, Wencheng; Wang, Dan; Couprie, Marie-emmanuelle; Lin, Guoqiang; Liu, Bo; Gu, Qiang; Wang, Dong; Zhao, Zhentang

    2014-12-01

    Removal of the undesired time-energy correlations in the electron beam is of paramount importance for efficient lasing of a high-gain free-electron laser. Recently, it has been theoretically and experimentally demonstrated that the longitudinal wakefield excited by the electrons themselves in a corrugated structure allows for precise control of the electron beam phase space. In this Letter, we report the first utilization of a corrugated structure as a beam linearizer in the operation of a seeded free-electron laser driven by a 140 MeV linear accelerator, where a gain of ˜10 000 over spontaneous emission was achieved at the second harmonic of the 1047 nm seed laser, and a free-electron laser bandwidth narrowing by 50% was observed, in good agreement with the theoretical expectations.

  17. Emission characteristics of organic light-emitting diodes and organic thin-films with planar and corrugated structures.

    PubMed

    Wei, Mao-Kuo; Lin, Chii-Wann; Yang, Chih-Chung; Kiang, Yean-Woei; Lee, Jiun-Haw; Lin, Hoang-Yan

    2010-04-12

    In this paper, we review the emission characteristics from organic light-emitting diodes (OLEDs) and organic molecular thin films with planar and corrugated structures. In a planar thin film structure, light emission from OLEDs was strongly influenced by the interference effect. With suitable design of microcavity structure and layer thicknesses adjustment, optical characteristics can be engineered to achieve high optical intensity, suitable emission wavelength, and broad viewing angles. To increase the extraction efficiency from OLEDs and organic thin-films, corrugated structure with micro- and nano-scale were applied. Microstructures can effectively redirects the waveguiding light in the substrate outside the device. For nanostructures, it is also possible to couple out the organic and plasmonic modes, not only the substrate mode.

  18. Analysis of dispersion and absorption characteristics of shear waves in sinusoidally corrugated elastic medium with void pores.

    PubMed

    Pandit, Deepak Kr; Kundu, Santimoy; Gupta, Shishir

    2017-02-01

    This theoretical work reports the dispersion and absorption characteristics of horizontally polarized shear wave (SH-wave) in a corrugated medium with void pores sandwiched between two dissimilar half-spaces. The dispersion and absorption equations have been derived in a closed form using the method of separation of variables. It has been established that there are two different kinds of wavefronts propagating in the proposed media. One of the wavefronts depends on the modulus of rigidity of elastic matrix of the medium and satisfies the dispersion equation of SH-waves. The second wavefront depends on the changes in volume fraction of the pores. Numerical computation of the obtained relations has been performed and the results are depicted graphically. The influence of corrugation, sandiness on the phase velocity and the damped velocity of SH-wave has been studied extensively.

  19. Emission Characteristics of Organic Light-Emitting Diodes and Organic Thin-Films with Planar and Corrugated Structures

    PubMed Central

    Wei, Mao-Kuo; Lin, Chii-Wann; Yang, Chih-Chung; Kiang, Yean-Woei; Lee, Jiun-Haw; Lin, Hoang-Yan

    2010-01-01

    In this paper, we review the emission characteristics from organic light-emitting diodes (OLEDs) and organic molecular thin films with planar and corrugated structures. In a planar thin film structure, light emission from OLEDs was strongly influenced by the interference effect. With suitable design of microcavity structure and layer thicknesses adjustment, optical characteristics can be engineered to achieve high optical intensity, suitable emission wavelength, and broad viewing angles. To increase the extraction efficiency from OLEDs and organic thin-films, corrugated structure with micro- and nano-scale were applied. Microstructures can effectively redirects the waveguiding light in the substrate outside the device. For nanostructures, it is also possible to couple out the organic and plasmonic modes, not only the substrate mode. PMID:20480033

  20. Analysis of dispersion and absorption characteristics of shear waves in sinusoidally corrugated elastic medium with void pores

    NASA Astrophysics Data System (ADS)

    Pandit, Deepak Kr.; Kundu, Santimoy; Gupta, Shishir

    2017-02-01

    This theoretical work reports the dispersion and absorption characteristics of horizontally polarized shear wave (SH-wave) in a corrugated medium with void pores sandwiched between two dissimilar half-spaces. The dispersion and absorption equations have been derived in a closed form using the method of separation of variables. It has been established that there are two different kinds of wavefronts propagating in the proposed media. One of the wavefronts depends on the modulus of rigidity of elastic matrix of the medium and satisfies the dispersion equation of SH-waves. The second wavefront depends on the changes in volume fraction of the pores. Numerical computation of the obtained relations has been performed and the results are depicted graphically. The influence of corrugation, sandiness on the phase velocity and the damped velocity of SH-wave has been studied extensively.

  1. Analysis of dispersion and absorption characteristics of shear waves in sinusoidally corrugated elastic medium with void pores

    PubMed Central

    Kundu, Santimoy; Gupta, Shishir

    2017-01-01

    This theoretical work reports the dispersion and absorption characteristics of horizontally polarized shear wave (SH-wave) in a corrugated medium with void pores sandwiched between two dissimilar half-spaces. The dispersion and absorption equations have been derived in a closed form using the method of separation of variables. It has been established that there are two different kinds of wavefronts propagating in the proposed media. One of the wavefronts depends on the modulus of rigidity of elastic matrix of the medium and satisfies the dispersion equation of SH-waves. The second wavefront depends on the changes in volume fraction of the pores. Numerical computation of the obtained relations has been performed and the results are depicted graphically. The influence of corrugation, sandiness on the phase velocity and the damped velocity of SH-wave has been studied extensively. PMID:28386416

  2. An Experimental Study on the Shear Hysteresis and Energy Dissipation of the Steel Frame with a Trapezoidal-Corrugated Steel Plate

    PubMed Central

    Shon, Sudeok; Yoo, Mina; Lee, Seungjae

    2017-01-01

    The steel frame reinforced with steel shear wall is a lateral load resisting system and has higher strength and shear performance than the concrete shear wall system. Especially, using corrugated steel plates in these shear wall systems improves out-of-plane stiffness and flexibility in the deformation along the corrugation. In this paper, a cyclic loading test of this steel frame reinforced with trapezoidal-corrugated steel plate was performed to evaluate the structural performance. The hysteresis behavior and the energy dissipation capacity of the steel frame were also compared according to the corrugated direction of the plate. For the test, one simple frame model without the wall and two frame models reinforced with the plate are considered and designed. The test results showed that the model reinforced with the corrugated steel plate had a greater accumulated energy dissipation capacity than the experimental result of the non-reinforced model. Furthermore, the energy dissipation curves of two reinforced frame models, which have different corrugated directions, produced similar results. PMID:28772624

  3. Rayleigh-Fourier-Kiselev approach to the problem of anomalous reflection-transmission of light by a corrugated film

    SciTech Connect

    Sopin, M.O.

    1994-07-01

    A thin-film optical waveguide with a periodically corrugated surface is considered during the incidence of a plane light wave. A system of equations for diffracted wave amplitudes is derived that is convenient for theoretical analysis. The suggested method of calculations of scattering amplitudes is applied to the rigorous solution of the problem of anomalous reflection-transmission of light. 17 refs., 3 figs.

  4. Particle trap to sheath non-binding contact for a gas-insulated transmission line having a corrugated outer conductor

    DOEpatents

    Fischer, William H.

    1984-04-24

    A non-binding particle trap to outer sheath contact for use in gas insulated transmission lines having a corrugated outer conductor. The non-binding feature of the contact according to the teachings of the invention is accomplished by having a lever arm rotatably attached to a particle trap by a pivot support axis disposed parallel to the direction of travel of the inner conductor/insulator/particle trap assembly.

  5. Our plastic age.

    PubMed

    Thompson, Richard C; Swan, Shanna H; Moore, Charles J; vom Saal, Frederick S

    2009-07-27

    Within the last few decades, plastics have revolutionized our daily lives. Globally we use in excess of 260 million tonnes of plastic per annum, accounting for approximately 8 per cent of world oil production. In this Theme Issue of Philosophical Transactions of the Royal Society, we describe current and future trends in usage, together with the many benefits that plastics bring to society. At the same time, we examine the environmental consequences resulting from the accumulation of waste plastic, the effects of plastic debris on wildlife and concerns for human health that arise from the production, usage and disposal of plastics. Finally, we consider some possible solutions to these problems together with the research and policy priorities necessary for their implementation.

  6. Our plastic age

    PubMed Central

    Thompson, Richard C.; Swan, Shanna H.; Moore, Charles J.; vom Saal, Frederick S.

    2009-01-01

    Within the last few decades, plastics have revolutionized our daily lives. Globally we use in excess of 260 million tonnes of plastic per annum, accounting for approximately 8 per cent of world oil production. In this Theme Issue of Philosophical Transactions of the Royal Society, we describe current and future trends in usage, together with the many benefits that plastics bring to society. At the same time, we examine the environmental consequences resulting from the accumulation of waste plastic, the effects of plastic debris on wildlife and concerns for human health that arise from the production, usage and disposal of plastics. Finally, we consider some possible solutions to these problems together with the research and policy priorities necessary for their implementation. PMID:19528049

  7. Plasticized phenolphthalein polycarbonate

    NASA Technical Reports Server (NTRS)

    Harrison, E. S.

    1976-01-01

    Phenolphthalein polycarbonate was successfully plasticized with polychlorinated biphenyls (e.g., Aroclor 1231) or tricresyl phosphate and cast from tetrahydrofuran to give clear films without loss of fire resistance. At loadings of 20 to 30 percent plasticizer the Tg was lowered to approximately 100 C which would render phenolphthalein polycarbonate easily moldable. Although these materials had some mechanical integrity as shown by their film forming ability, the room temperature toughness of the plasticized polymer was not significantly improved over unmodified polymer.

  8. Evaporation heat transfer and friction characteristics of R-134a flowing downward in a vertical corrugated tube

    SciTech Connect

    Aroonrat, Kanit; Wongwises, Somchai

    2011-01-15

    Differently from most previous studies, the heat transfer and friction characteristics of the pure refrigerant HFC-134a during evaporation inside a vertical corrugated tube are experimentally investigated. The double tube test sections are 0.5 m long with refrigerant flowing in the inner tube and heating water flowing in the annulus. The inner tubes are one smooth tube and two corrugated tubes, which are constructed from smooth copper tube of 8.7 mm inner diameter. The test runs are performed at evaporating temperatures of 10, 15, and 20 C, heat fluxes of 20, 25, and 30 kW/m{sup 2}, and mass fluxes of 200, 300, and 400 kg/m{sup 2} s. The quality of the refrigerant in the test section is calculated using the temperature and pressure obtained from the experiment. The pressure drop across the test section is measured directly by a differential pressure transducer. The effects of heat flux, mass flux, and evaporation temperature on the heat transfer coefficient and two-phase friction factor are also discussed. It is found that the percentage increases of the heat transfer coefficient and the two-phase friction factor of the corrugated tubes compared with those of the smooth tube are approximately 0-10% and 70-140%, respectively. (author)

  9. Electrical and structural properties of antimony-doped p-type ZnO nanorods with self-corrugated surfaces.

    PubMed

    Kang, Jang-Won; Choi, Yong-Seok; Choe, Minhyeok; Kim, Na-Yeong; Lee, Takhee; Kim, Bong-Joong; Tu, C W; Park, Seong-Ju

    2012-12-14

    We report on p-type conductivity in antimony (Sb)-doped ZnO (ZnO:Sb) nanorods which have self-corrugated surfaces. The p-ZnO:Sb/n-ZnO nanorod diode shows good rectification characteristics, confirming that a p-n homojunction is formed in the ZnO nanorod diode. The low-temperature photoluminescence (PL) spectra of the ZnO:Sb nanorods reveal that the p-type conductivity in p-ZnO:Sb is related to the Sb(Zn)-2V(Zn) complex acceptors. Transmission electron microscopy (TEM) analysis of the ZnO:Sb nanorods also shows that the p-type conductivity is attributed to the Sb(Zn)-2V(Zn) complex acceptors which can be easily formed near the self-corrugated surface regions of ZnO:Sb nanorods. These results suggest that the Sb(Zn)-2V(Zn) complex acceptors are mainly responsible for the p-type conductivity in ZnO:Sb nanorods which have corrugated surfaces.

  10. Trend extraction of rail corrugation measured dynamically based on the relevant low-frequency principal components reconstruction

    NASA Astrophysics Data System (ADS)

    Li, Yanfu; Liu, Hongli; Ma, Ziji

    2016-10-01

    Rail corrugation dynamic measurement techniques are critical to guarantee transport security and guide rail maintenance. During the inspection process, low-frequency trends caused by rail fluctuation are usually superimposed on rail corrugation and seriously affect the assessment of rail maintenance quality. In order to extract and remove the nonlinear and non-stationary trends from original mixed signals, a hybrid model based ensemble empirical mode decomposition (EEMD) and modified principal component analysis (MPCA) is proposed in this paper. Compared with the existing de-trending methods based on EMD, this method first considers low-frequency intrinsic mode functions (IMFs) thought to be underlying trend components that maybe contain some unrelated components, such as white noise and low-frequency signal itself, and proposes to use PCA to accurately extract the pure trends from the IMFs containing multiple components. On the other hand, due to the energy contribution ratio between trends and mixed signals is prior unknown, and the principal components (PCs) decomposed by PCA are arranged in order of energy reduction without considering frequency distribution, the proposed method modifies traditional PCA and just selects relevant low-frequency PCs to reconstruct the trends based on the zero-crossing numbers (ZCN) of each PC. Extensive tests are presented to illustrate the effectiveness of the proposed method. The results show the proposed EEMD-PCA-ZCN is an effective tool for trend extraction of rail corrugation measured dynamically.

  11. Tunable and efficient terahertz radiation generation by photomixing of two super Gaussian laser pulses in a corrugated magnetized plasma

    SciTech Connect

    Varshney, Prateek; Sajal, Vivek Kumar, Ravindra; Sharma, Navneet K.; Singh, Kunwar Pal

    2015-05-21

    A scheme of terahertz (THz) radiation generation is investigated by photo-mixing of two super Gaussian laser beams having different frequencies (ω{sub 1}, ω{sub 2}) and wave numbers (k{sup →}{sub 1}, k{sup →}{sub 2}) in a performed corrugated plasma embedded with transverse dc magnetic field. Lasers exert a nonlinear ponderomotive force, imparting an oscillatory velocity to plasma electrons that couples with the density corrugations (n{sup ′}=n{sub α0}e{sup iαz}) to generate a strong transient nonlinear current, that resonantly derives THz radiation of frequency ∼ω{sub h} (upper hybrid frequency). The periodicity of density corrugations is suitably chosen to transfer maximum momentum from lasers to THz radiation at phase matching conditions ω=ω{sub 1}−ω{sub 2} and k{sup →}=k{sup →}{sub 1}−k{sup →}{sub 2}+α{sup →}. The efficiency, power, beam quality, and tunability of the present scheme exhibit high dependency upon the applied transverse dc magnetic field along with q-indices and beam width parameters (a{sub 0}) of super Gaussian lasers. In the present scheme, efficiency ∼10{sup −2} is achieved with the optimization of all these parameters.

  12. A corrugated mesoscale structure on electrode-electrolyte interface for enhancing cell performance in anode-supported SOFC

    NASA Astrophysics Data System (ADS)

    Konno, Akio; Iwai, Hiroshi; Saito, Motohiro; Yoshida, Hideo

    For enhancing the power density of a solid oxide fuel cell, mesoscale-structure control of electrode-electrolyte interfaces in an anode-supported cell is proposed. We define 'mesoscale' as a size range of the order of 10-100 μm which is larger than the 'microscale' of electrode particles but smaller than the 'macroscale' of cell geometries. Mesoscale-structure control enlarges the electrode-electrolyte interface, and this enlargement extends an active electrochemical reaction zone where a charge-transfer reaction occurs actively near the interface. A corrugated mesoscale electrolyte was adopted which enlarged the interface structures of both anode and cathode sides. We performed a 2-D numerical simulation, and discussed the effects of such structure not only on the overall performance but also on the detailed distributions of electric potentials, gas concentrations and local electrochemical reaction rate. As a result, it was observed that the corrugated mesoscale structure reduced both activation overpotential and ohmic loss by ion transport, and hence enhanced the power generation performance. When the interface area enlargement factor was 1.73, an enhancement of a power density having a maximum value of 59% was achieved with the mesoscale-corrugated cell rather than with the flat cell.

  13. Additives in plastics.

    PubMed

    Deanin, R D

    1975-06-01

    The polymers used in plastics are generally harmless. However, they are rarely used in pure form. In almost all commercial plastics, they are "compounded" with monomeric ingredients to improve their processing and end-use performance. In order of total volume used, these monomeric additives may be classified as follows: reinforcing fibers, fillers, and coupling agents; plasticizers; colorants; stabilizers (halogen stabilizers, antioxidants, ultraviolet absorbers, and biological preservatives); processing aids (lubricants, others, and flow controls); flame retardants, peroxides; and antistats. Some information is already available, and much more is needed, on potential toxicity and safe handling of these additives during processing and manufacture of plastics products.

  14. Additives in plastics.

    PubMed Central

    Deanin, R D

    1975-01-01

    The polymers used in plastics are generally harmless. However, they are rarely used in pure form. In almost all commercial plastics, they are "compounded" with monomeric ingredients to improve their processing and end-use performance. In order of total volume used, these monomeric additives may be classified as follows: reinforcing fibers, fillers, and coupling agents; plasticizers; colorants; stabilizers (halogen stabilizers, antioxidants, ultraviolet absorbers, and biological preservatives); processing aids (lubricants, others, and flow controls); flame retardants, peroxides; and antistats. Some information is already available, and much more is needed, on potential toxicity and safe handling of these additives during processing and manufacture of plastics products. PMID:1175566

  15. Plastics and health risks.

    PubMed

    Halden, Rolf U

    2010-01-01

    By 2010, the worldwide annual production of plastics will surpass 300 million tons. Plastics are indispensable materials in modern society, and many products manufactured from plastics are a boon to public health (e.g., disposable syringes, intravenous bags). However, plastics also pose health risks. Of principal concern are endocrine-disrupting properties, as triggered for example by bisphenol A and di-(2-ethylhexyl) phthalate (DEHP). Opinions on the safety of plastics vary widely, and despite more than five decades of research, scientific consensus on product safety is still elusive. This literature review summarizes information from more than 120 peer-reviewed publications on health effects of plastics and plasticizers in lab animals and humans. It examines problematic exposures of susceptible populations and also briefly summarizes adverse environmental impacts from plastic pollution. Ongoing efforts to steer human society toward resource conservation and sustainable consumption are discussed, including the concept of the 5 Rs--i.e., reduce, reuse, recycle, rethink, restrain--for minimizing pre- and postnatal exposures to potentially harmful components of plastics.

  16. Graphene on Ni(111): Electronic Corrugation and Dynamics from Helium Atom Scattering

    PubMed Central

    2015-01-01

    Using helium atom scattering, we have studied the structure and dynamics of a graphene layer prepared in situ on a Ni(111) surface. Graphene/Ni(111) exhibits a helium reflectivity of ∼20% for a thermal helium atom beam and a particularly small surface electron density corrugation ((0.06 ± 0.02) Å peak to peak height). The Debye–Waller attenuation of the elastic diffraction peaks of graphene/Ni(111) and Ni(111) was measured at surface temperatures between 150 and 740 K. A surface Debye temperature of θD = (784 ± 14) K is determined for the graphene/Ni(111) system and θD = (388 ± 7) K for Ni(111), suggesting that the interlayer interaction between graphene and the Ni substrate is intermediary between those for strongly interacting systems like graphene/Ru(0001) and weakly interacting systems like graphene/Pt(111). In addition we present measurements of low frequency surface phonon modes on graphene/Ni(111) where the phonon modes of the Ni(111) substrate can be clearly observed. The similarity of these findings with the graphene/Ru(0001) system indicates that the bonding of graphene to a metal substrate alters the dynamic properties of the graphene surface strongly and is responsible for the high helium reflectivity of these systems. PMID:26617683

  17. Ratcheting of Brownian swimmers in periodically corrugated channels: A reduced Fokker-Planck approach

    NASA Astrophysics Data System (ADS)

    Yariv, Ehud; Schnitzer, Ory

    2014-09-01

    We consider the motion of self-propelling Brownian particles in two-dimensional periodically corrugated channels. The point-size swimmers propel themselves in a direction which fluctuates by Brownian rotation; in addition, they undergo Brownian motion. The impermeability of the channel boundaries in conjunction with an asymmetry of the unit-cell geometry enables ratcheting, where a nonzero particle current is animated along the channel. This effect is studied here in the continuum limit using a diffusion-advection description of the probability density in a four-dimensional position-orientation space. Specifically, the mean particle velocity is calculated using macrotransport (generalized Taylor-dispersion) theory. This description reveals that the ratcheting mechanism is indirect: swimming gives rise to a biased spatial particle distribution which in turn results in a purely diffusive net current. For a slowly varying channel geometry, the dependence of this current upon the channel geometry and fluid-particle parameters is studied via a long-wave approximation over a reduced two-dimensional space. This allows for a straightforward seminumerical solution. In the limit where both rotational diffusion and swimming are strong, we find an asymptotic approximation to the particle current, scaling inversely with the square of the swimming Péclet number. For a given swimmer-fluid system, this limit is physically realized with increasing unit-cell size.

  18. Ratcheting of Brownian swimmers in periodically corrugated channels: a reduced Fokker-Planck approach.

    PubMed

    Yariv, Ehud; Schnitzer, Ory

    2014-09-01

    We consider the motion of self-propelling Brownian particles in two-dimensional periodically corrugated channels. The point-size swimmers propel themselves in a direction which fluctuates by Brownian rotation; in addition, they undergo Brownian motion. The impermeability of the channel boundaries in conjunction with an asymmetry of the unit-cell geometry enables ratcheting, where a nonzero particle current is animated along the channel. This effect is studied here in the continuum limit using a diffusion-advection description of the probability density in a four-dimensional position-orientation space. Specifically, the mean particle velocity is calculated using macrotransport (generalized Taylor-dispersion) theory. This description reveals that the ratcheting mechanism is indirect: swimming gives rise to a biased spatial particle distribution which in turn results in a purely diffusive net current. For a slowly varying channel geometry, the dependence of this current upon the channel geometry and fluid-particle parameters is studied via a long-wave approximation over a reduced two-dimensional space. This allows for a straightforward seminumerical solution. In the limit where both rotational diffusion and swimming are strong, we find an asymptotic approximation to the particle current, scaling inversely with the square of the swimming Péclet number. For a given swimmer-fluid system, this limit is physically realized with increasing unit-cell size.

  19. Two-dimensional corrugated flames - a consequence of the Darrieus-Landau instability

    NASA Astrophysics Data System (ADS)

    Patyal, Advitya; Matalon, Moshe

    2016-11-01

    In this study we present for the first time the development of corrugated flame surfaces resulting from gas expansion in a three-dimensional flow as a consequence of the Darrieus-Landau instability. The computations are carried out within the context of the hydrodynamic theory where the flame is treated as a surface of density discontinuity separating burned gas from the fresh combustible mixture, and its movement is tracked via a level-set method with a propagation speed that depends on the local curvature and hydrodynamic strain. To this end, a surface parameterization method is used to accurately capture the velocity jump across the flame and the strain rate along the flame interface. The numerical scheme is shown to accurately recover the exact pole-solutions predicted by the nonlinear Michelson-Sivashinsky equation in the weak gas expansion limit, and corroborates the bifurcation results from linear stability analysis. It is shown that, in accord with experimental observations, the new conformations that evolve beyond the instability threshold have a sharp crest pointing towards the burned gas with ridges along the troughs, and that these structures propagate steadily, nearly 50% faster than planar flames.

  20. Corrugation-Pitch-Modulated Distributed Feedback Lasers with Ultranarrow Spectral Linewidth

    NASA Astrophysics Data System (ADS)

    Okai, Makoto; Suzuki, Makoto; Taniwatari, Tuyoshi; Chinone, Naoki

    1994-05-01

    We demonstrate that the spectral linewidth of distributed feedback (DFB) semiconductor lasers can be reduced by suppressing the longitudinal spatial hole-burning (SHB) effect. We confirm that the minimum spectral linewidth of lattice-matched multiple-quantum-well λ/4-shifted DFB (lattice-matched MQW-λ/4-DFB) lasers is limited by the SHB effect and we show that a corrugation-pitch-modulated (CPM) grating structure reduces the SHB effect while maintaining stable single-mode oscillation: at an output power of 25 mW, a lattice-matched MQW-CPM-DFB laser gives a spectral linewidth of 56 kHz. We further introduced the strained MQW structure into the CPM-DFB laser to obtain a narrower spectral linewidth. Introducing a 1.0% compressively strained MQW active layer into a CPM-DFB laser gives a spectral linewidth of 3.6 kHz at 55-mW output power and a linewidth floor (residual linewidth for extrapolated infinite output power) of 2 kHz and results in a linewidth-power product of 140 kHz·mW.

  1. Corrugated paraffin nanocomposite films as large stroke thermal actuators and self-activating thermal interfaces.

    PubMed

    Copic, Davor; Hart, A John

    2015-04-22

    High performance active materials are of rapidly growing interest for applications including soft robotics, microfluidic systems, and morphing composites. In particular, paraffin wax has been used to actuate miniature pumps, solenoid valves, and composite fibers, yet its deployment is typically limited by the need for external volume constraint. We demonstrate that compact, high-performance paraffin actuators can be made by confining paraffin within vertically aligned carbon nanotube (CNT) films. This large-stroke vertical actuation is enabled by strong capillary interaction between paraffin and CNTs and by engineering the CNT morphology by mechanical compression before capillary-driven infiltration of the molten paraffin. The maximum actuation strain of the corrugated CNT-paraffin films (∼0.02-0.2) is comparable to natural muscle, yet the maximum stress is limited to ∼10 kPa by collapse of the CNT network. We also show how a CNT-paraffin film can serve as a self-activating thermal interface that closes a gap when it is heated. These new CNT-paraffin film actuators could be produced by large-area CNT growth, infiltration, and lamination methods, and are attractive for use in miniature systems due to their self-contained design.

  2. Mechanisms of amplification of ultrashort electromagnetic pulses in gyrotron traveling wave tube with helically corrugated waveguide

    SciTech Connect

    Ginzburg, N. S. Zaslavsky, V. Yu.; Zotova, I. V.; Sergeev, A. S.; Zheleznov, I. V.; Samsonov, S. V.; Mishakin, S. V.

    2015-11-15

    A time-domain self consistent theory of a gyrotron traveling wave tube with a helically corrugated operating waveguide has been developed. Based on this model, the process of short pulse amplification was studied in regimes of grazing and intersection of the dispersion curves of the electromagnetic wave and the electron beam. In the first case, the possibility of amplification without pulse form distortion was demonstrated for the pulse spectrum width of the order of the gain bandwidth. In the second case, when the electrons' axial velocity was smaller than the wave's group velocity, it was shown that the slippage of the incident signal with respect to the electron beam provides feeding of the signal by “fresh” electrons without initial modulation. As a result, the amplitude of the output pulse can exceed the amplitude of its saturated value for the case of the grazing regime, and, for optimal parameters, the peak output power can be even larger than the kinetic power of the electron beam.

  3. Electronic and thermal transport study of sinusoidally corrugated nanowires aiming to improve thermoelectric efficiency

    NASA Astrophysics Data System (ADS)

    Park, K. H.; Martin, P. N.; Ravaioli, U.

    2016-01-01

    Improvement of thermoelectric efficiency has been very challenging in the solid-state industry due to the interplay among transport coefficients which measure the efficiency. In this work, we modulate the geometry of nanowires to interrupt thermal transport with causing only a minimal impact on electronic transport properties, thereby maximizing the thermoelectric power generation. As it is essential to scrutinize comprehensively both electronic and thermal transport behaviors for nano-scale thermoelectric devices, we investigate the Seebeck coefficient, the electrical conductance, and the thermal conductivity of sinusoidally corrugated silicon nanowires and eventually look into an enhancement of the thermoelectric figure-of-merit ZT from the modulated nanowires over typical straight nanowires. A loss in the electronic transport coefficient is calculated with the recursive Green function along with the Landauer formalism, and the thermal transport is simulated with the molecular dynamics. In contrast to a small influence on the thermopower and the electrical conductance of the geometry-modulated nanowires, a large reduction of the thermal conductivity yields an enhancement of the efficiency by 10% to 35% from the typical nanowires. We find that this approach can be easily extended to various structures and materials as we consider the geometrical modulation as a sole source of perturbation to the system.

  4. Diffraction inspired unidirectional and bidirectional beam splitting in defect-containing photonic structures without interface corrugations

    SciTech Connect

    Colak, Evrim; Serebryannikov, Andriy E.; Usik, P. V.; Ozbay, Ekmel

    2016-05-21

    It is shown that strong diffractions and related dual-beam splitting can be obtained at transmission through the nonsymmetric structures that represent two slabs of photonic crystal (PhC) separated by a single coupled-cavity type defect layer, while there are no grating-like corrugations at the interfaces. The basic operation regimes include unidirectional and bidirectional splitting that occur due to the dominant contribution of the first positive and first negative diffraction orders to the transmission, which is typically connected with different manifestations of the asymmetric transmission phenomenon. Being the main component of the resulting transmission mechanism, diffractions appear owing to the effect exerted by the defect layer that works like an embedded diffractive element. Two mechanisms can co-exist in one structure, which differ, among others, in that whether dispersion allows coupling of zero order to a wave propagating in the regular, i.e., defect-free PhC segments or not. The possibility of strong diffractions and efficient splitting related to it strongly depend on the dispersion properties of the Floquet-Bloch modes of the PhC. Existence of one of the studied transmission scenarios is not affected by location of the defect layer.

  5. Sound Transmission Loss Through a Corrugated-Core Sandwich Panel with Integrated Acoustic Resonators

    NASA Technical Reports Server (NTRS)

    Schiller, Noah H.; Allen, Albert R.; Zalewski, Bart F; Beck, Benjamin S.

    2014-01-01

    The goal of this study is to better understand the effect of structurally integrated resonators on the transmission loss of a sandwich panel. The sandwich panel has facesheets over a corrugated core, which creates long aligned chambers that run parallel to the facesheets. When ports are introduced through the facesheet, the long chambers within the core can be used as low-frequency acoustic resonators. By integrating the resonators within the structure they contribute to the static load bearing capability of the panel while also attenuating noise. An analytical model of a panel with embedded resonators is derived and compared with numerical simulations. Predictions show that acoustic resonators can significantly improve the transmission loss of the sandwich panel around the natural frequency of the resonators. In one configuration with 0.813 m long internal chambers, the diffuse field transmission loss is improved by more than 22 dB around 104 Hz. The benefit is achieved with no added mass or volume relative to the baseline structure. The embedded resonators are effective because they radiate sound out-of-phase with the structure. This results in destructive interference, which leads to less transmitted sound power.

  6. Dynamic test of a corrugated steel keyworker blast shelter MISTY PICTURE. Final report

    SciTech Connect

    Holmes, R.L.; Slawson, T.R.; Harris, A.L.

    1987-11-01

    The 18-man blast shelter was tested dynamically on May 14, 1987 in the MISTY PICTURE event at White Sands Missile Range, NM. The main section of the shelter was fabricated from a 9-foot-diameter, 27.5-foot-long section of 10-gage, galvanized, corrugated steel culvert. The shelter included a vertical entryway and air intake and exhaust stacks. The shelter design was found to be conservative during a previous 50-psi validation test, and some constructibility problems were encountered with the entryway-to-shelter connections. This test was conducted to validate the modifications made to the shelter design. The modifications were made to reduce construction costs and improve constructibility. Primary modifications included: replacing the stiffened endwalls with lighter-weight unstiffened plates, connecting the entryway to an endwall rather than to the main section of the shelter, and the inclusion of an emergency exit. The structure was located at the anticipated 200-psi peak overpressure level. Post-test inspection revealed that the main section of the shelter suffered very little damage during the test. Due to the failure of the emergency exit cover plate, it was necessary to determine if enough pressure entered the shelter to affect its structural response. This test also investigated the shock environment inside the shelter.

  7. Dynamic test of a corrugated steel keyworker blast shelter. Final report

    SciTech Connect

    Woodson, S.C.; Slawson, T.R.; Holmes, R.L.

    1986-05-01

    At the time this study was initiated, civil defense planning in the United States called for the evacuation of nonessential personnel to safe host areas when a nuclear attack is probable, requiring the construction of blast shelters to protect the key workers remaining in the risk areas. A full-scale corrugated steel keyworker blast shelter was dynamically tested using the High Explosive Simulation Technique (HEST). The test primarily investigated the structural design of the shelter and entryway, survivability of the air-moving system components, and occupant survivability. Alternate blast designs for the 18-man shelter were also tested. The test showed that the structure can withstand a 55-psi peak overpressure loading from a 1-MT nuclear detonation with only minor damage. In-structure shock was within acceptable limits for occupants. However, typical floor-mounted shelter equipment should be shock-isolated with pads to ensure survivability. Structural modifications to decrease the cost and increase the ease of installation of the structure are recommended.

  8. Bright unidirectional fluorescence emission of molecules in a nanoaperture with plasmonic corrugations.

    PubMed

    Aouani, Heykel; Mahboub, Oussama; Bonod, Nicolas; Devaux, Eloïse; Popov, Evgeny; Rigneault, Hervé; Ebbesen, Thomas W; Wenger, Jérôme

    2011-02-09

    Controlling the fluorescence emission from nanoscale quantum emitters is a key element for a wide range of applications, from efficient analytical sensing to quantum information processing. Enhancing the fluorescence intensity and narrowing the emission directivity are both essential features to achieve a full control of fluorescence, yet this is rarely obtained simultaneously with optical nanoantennas. Here we report that gold nanoapertures surrounded by periodic corrugations transform standard fluorescent molecules into bright unidirectional sources. We obtain enhancement factors of the fluorescence count rate per molecule up to 120 fold simultaneously with a directional emission of the fluorescence into a narrow angular cone in the direction normal to the sample plane. The bright emission and narrow directionality enable the detection of single molecules with a low numerical aperture objective, and improve the effectiveness of fluorescence-based applications. We thoroughly quantify the increased light-matter coupling as well as the radiation pattern intensity. These results are highly relevant for the development of single molecule sensing, single-photon sources, and light emitting devices.

  9. On the modeling of modes coupling in dissipative fluid-filled waveguide with corrugated surfaces

    NASA Astrophysics Data System (ADS)

    Valier-Brasier, Tony; Potel, Catherine; Bruneau, Michel

    2009-08-01

    This paper aims at providing an alternative analytical model, which would be more suitable than a previous one [C. Potel and M. Bruneau, J. Sound Vib. 313, 738 (2008)], to describe the mode coupling due to scattering on small one-dimensional irregularities (parallel ridges) of the surfaces of a fluid-filled waveguide. Both models rely on standard integral formulation and modal analysis, the acoustic field being expressed as a coupling between eigenmodes of a regularly shaped waveguide, which bounds outwardly the corrugated waveguide considered. But the model presented here departs from the previous one essentially because it starts from the integral formulation for the acoustic pressure field, the solution relying on a modal expansion, whereas the previous one starts from the inner product of the set of differential equations (which govern the acoustic pressure field) and the appropriate eigenfunctions, the solution being obtained from using a one-dimensional integral formulation. Substituting this alternative model for the previous one clearly accelerates convergences (even permits to avoid divergences) of the iterative process used to solve the problem. Finally, complex eigenfunctions are introduced here in order to account for the dissipative effects due to thermoviscous phenomena (through an impedancelike boundary condition), which is of importance at the cut-off frequencies.

  10. SHOCK CORRUGATION BY RAYLEIGH-TAYLOR INSTABILITY IN GAMMA-RAY BURST AFTERGLOW JETS

    SciTech Connect

    Duffell, Paul C.; MacFadyen, Andrew I. E-mail: macfadyen@nyu.edu

    2014-08-10

    Afterglow jets are Rayleigh-Taylor unstable and therefore turbulent during the early part of their deceleration. There are also several processes which actively cool the jet. In this Letter, we demonstrate that if cooling significantly increases the compressibility of the flow, the turbulence collides with the forward shock, destabilizing and corrugating it. In this case, the forward shock is turbulent enough to produce the magnetic fields responsible for synchrotron emission via small-scale turbulent dynamo. We calculate light curves assuming the magnetic field is in energy equipartition with the turbulent kinetic energy and discover that dynamic magnetic fields are well approximated by a constant magnetic-to-thermal energy ratio of 1%, though there is a sizeable delay in the time of peak flux as the magnetic field turns on only after the turbulence has activated. The reverse shock is found to be significantly more magnetized than the forward shock, with a magnetic-to-thermal energy ratio of the order of 10%. This work motivates future Rayleigh-Taylor calculations using more physical cooling models.

  11. Implementation of the CMOS MEMS condenser microphone with corrugated metal diaphragm and silicon back-plate.

    PubMed

    Huang, Chien-Hsin; Lee, Chien-Hsing; Hsieh, Tsung-Min; Tsao, Li-Chi; Wu, Shaoyi; Liou, Jhyy-Cheng; Wang, Ming-Yi; Chen, Li-Che; Yip, Ming-Chuen; Fang, Weileun

    2011-01-01

    This study reports a CMOS-MEMS condenser microphone implemented using the standard thin film stacking of 0.35 μm UMC CMOS 3.3/5.0 V logic process, and followed by post-CMOS micromachining steps without introducing any special materials. The corrugated diaphragm for the microphone is designed and implemented using the metal layer to reduce the influence of thin film residual stresses. Moreover, a silicon substrate is employed to increase the stiffness of the back-plate. Measurements show the sensitivity of microphone is -42 ± 3 dBV/Pa at 1 kHz (the reference sound-level is 94 dB) under 6 V pumping voltage, the frequency response is 100 Hz-10 kHz, and the S/N ratio >55 dB. It also has low power consumption of less than 200 μA, and low distortion of less than 1% (referred to 100 dB).

  12. Numerical study of three-dimensional sound reflection from corrugated surface waves.

    PubMed

    Choo, Youngmin; Song, H C; Seong, Woojae

    2016-10-01

    When a sound wave propagates in a water medium bounded by a smooth surface wave, reflection from a wave crest can lead to focusing and result in rapid variation of the received waveform as the surface wave moves [Tindle, Deane, and Preisig, J. Acoust. Soc. Am. 125, 66-72 (2009)]. In prior work, propagation paths have been constrained to be in a plane parallel to the direction of corrugated surface waves, i.e., a two-dimensional (2-D) propagation problem. In this paper, the azimuthal dependence of sound propagation as a three-dimensional (3-D) problem is investigated using an efficient, time-domain Helmholtz-Kirchhoff integral formulation. When the source and receiver are in the plane orthogonal to the surface wave direction, the surface wave curvature vanishes in conventional 2-D treatments and the flat surface simply moves up and down, resulting in minimal temporal variation of the reflected signal intensity. On the other hand, the 3-D propagation analysis reveals that a focusing phenomenon occurs in the reflected signal due to the surface wave curvature formed along the orthogonal plane, i.e., out-of-plane scattering.

  13. Disrupting the wall accumulation of human sperm cells by artificial corrugation

    PubMed Central

    Jeyaram, Y.; Condat, C. A.; Oviedo, M.; Berdakin, I.; Moshchalkov, V. V.; Giojalas, L. C.; Silhanek, A. V.; Marconi, V. I.

    2015-01-01

    Many self-propelled microorganisms are attracted to surfaces. This makes their dynamics in restricted geometries very different from that observed in the bulk. Swimming along walls is beneficial for directing and sorting cells, but may be detrimental if homogeneous populations are desired, such as in counting microchambers. In this work, we characterize the motion of human sperm cells ∼60 μm long, strongly confined to ∼25 μm shallow chambers. We investigate the nature of the cell trajectories between the confining surfaces and their accumulation near the borders. Observed cell trajectories are composed of a succession of quasi-circular and quasi-linear segments. This suggests that the cells follow a path of intermittent trappings near the top and bottom surfaces separated by stretches of quasi-free motion in between the two surfaces, as confirmed by depth resolved confocal microscopy studies. We show that the introduction of artificial petal-shaped corrugation in the lateral boundaries removes the tendency of cells to accumulate near the borders, an effect which we hypothesize may be valuable for microfluidic applications in biomedicine. PMID:26015834

  14. Graphene on Ni(111): Electronic Corrugation and Dynamics from Helium Atom Scattering.

    PubMed

    Tamtögl, Anton; Bahn, Emanuel; Zhu, Jianding; Fouquet, Peter; Ellis, John; Allison, William

    2015-11-19

    Using helium atom scattering, we have studied the structure and dynamics of a graphene layer prepared in situ on a Ni(111) surface. Graphene/Ni(111) exhibits a helium reflectivity of ∼20% for a thermal helium atom beam and a particularly small surface electron density corrugation ((0.06 ± 0.02) Å peak to peak height). The Debye-Waller attenuation of the elastic diffraction peaks of graphene/Ni(111) and Ni(111) was measured at surface temperatures between 150 and 740 K. A surface Debye temperature of θD = (784 ± 14) K is determined for the graphene/Ni(111) system and θD = (388 ± 7) K for Ni(111), suggesting that the interlayer interaction between graphene and the Ni substrate is intermediary between those for strongly interacting systems like graphene/Ru(0001) and weakly interacting systems like graphene/Pt(111). In addition we present measurements of low frequency surface phonon modes on graphene/Ni(111) where the phonon modes of the Ni(111) substrate can be clearly observed. The similarity of these findings with the graphene/Ru(0001) system indicates that the bonding of graphene to a metal substrate alters the dynamic properties of the graphene surface strongly and is responsible for the high helium reflectivity of these systems.

  15. Hierarchical synthesis of corrugated photocatalytic TiO2 microsphere architectures on natural pollen surfaces

    NASA Astrophysics Data System (ADS)

    Erdogan, Deniz Altunoz; Ozensoy, Emrah

    2017-05-01

    Biomaterials are challenging, yet vastly promising templates for engineering unusual inorganic materials with unprecedented surface and structural properties. In the current work, a novel biotemplate-based photocatalytic material was synthesized in the form of corrugated TiO2 microspheres by utilizing a sol-gel methodology where Ambrosia trifida (Ab, Giant ragweed) pollen was exploited as the initial biological support surface. Hierarchically synthesized TiO2 microspheres were structurally characterized in detail via SEM-EDX, Raman spectroscopy, XRD and BET techniques in order to shed light on the surface chemistry, crystal structure, chemical composition and morphology of these novel material architectures. Photocatalytic functionality of the synthesized materials was demonstrated both in gas phase as well as in liquid phase. Along these lines, air and water purification capabilities of the synthesized TiO2 microspheres were established by performing photocatalytic oxidative NOx(g) storage and Rhodamine B(aq) degradation experiments; respectively. The synthetic approach presented herein offers new opportunities to design and create sophisticated functional materials that can be used in micro reactor systems, adsorbents, drug delivery systems, catalytic processes, and sensor technologies.

  16. Contact angle hysteresis and meniscus corrugation on randomly heterogeneous surfaces with mesa-type defects.

    PubMed

    Iliev, Dimitar; Pesheva, Nina; Iliev, Stanimir

    2013-05-14

    The results of a numerical study of the various characteristics of the static contact of a liquid meniscus with a flat but heterogeneous surface, consisting of two types of homogeneous materials, forming regularly and randomly distributed microscopic defects are presented. The solutions for the meniscus shape are obtained numerically using the full expression of the system free energy functional. The goal is to establish how the magnitude and the limits of the hysteresis interval of the equilibrium contact angle, the Cassie's angle, and the contact line (CL) roughness exponent are related to the parameters, characterizing the heterogeneous surface-the equilibrium contact angles on the two materials and their fractions. We compare the results of different ways of determining the averaged contact angle on heterogeneous surfaces. We study the spread of the CL corrugation along the liquid meniscus. We compare our results with the numerical results, obtained using linearized energy functional, and also with experimental results for the CL roughness exponent. The obtained results support the conclusion that some characteristics depends on the type (regular or random) of the heterogeneity pattern.

  17. Corrugated velocity patterns in the spiral galaxies: NGC 278, NGC 1058, NGC 2500 & UGC 3574

    NASA Astrophysics Data System (ADS)

    Sánchez-Gil, M. Carmen; Alfaro, Emilio J.; Pérez, Enrique

    2015-12-01

    We address the study of the H α vertical velocity field in a sample of four nearly face-on galaxies using long-slit spectroscopy taken with the Intermediate dispersion Spectrograph and Imaging System (ISIS), attached to the William Herschel Telescope (WHT) at the Roque de los Muchachos Observatory (Spain). The spatial structure of the velocity vertical component shows a radial corrugated pattern with spatial scales higher or within the order of 1 kpc. The gas is mainly ionized by high-energy photons: only in some locations of NGC 278 and NGC 1058 is there some evidence of ionization by low-velocity shocks, which, in the case of NGC 278, could be due to minor mergers. The behaviour of the gas in the neighbourhood of the spiral arms fits, in the majority of the observed cases, with that predicted by the so-called hydraulic bore mechanism, where a thick magnetized disc encounters a spiral density perturbation. The results obtained show that it is difficult to explain the H α large-scale velocity field without the presence of a magnetized, thick galactic disc. Larger samples and spatial covering of the galaxy discs are needed to provide further insight into this problem.

  18. Immobilizing individual atoms beneath a corrugated single layer of boron nitride.

    PubMed

    Cun, Huanyao; Iannuzzi, Marcella; Hemmi, Adrian; Roth, Silvan; Osterwalder, Jürg; Greber, Thomas

    2013-05-08

    Single atoms, and in particular the least reactive noble gases, are difficult to immobilize at room temperature. Ion implantation into a crystal lattice has this capability, but the randomness of the involved processes does not permit much control over their distribution within the solid. Here we demonstrate that the boron nitride nanomesh, a corrugated single layer of hexagonal boron nitride (h-BN) with a 3.2 nm honeycomb superstructure formed on a Rh(111) surface, can trap individual argon atoms at distinct subsurface sites at room temperature. A kinetic energy window for implantation is identified where the argon ions can penetrate the h-BN layer but not enter the Rh lattice. Scanning tunneling microscopy and photoemission data show the presence of argon atoms at two distinct sites within the nanomesh unit cell, confirmed also by density functional theory calculations. The single atom implants are stable in air. Annealing of implanted structures to 900 K induces the formation of highly regular holes of 2 nm diameter in the h-BN layer with adjacent flakes of the same size found on top of the layer. We explain this "can-opener" effect by the presence of a vacancy defect, generated during the penetration of the Ar ion through the h-BN lattice, and propagating along the rim of a nanomesh pore where the h-BN lattice is highly bent. The reported effects are also observed in graphene on ruthenium and for neon atoms.

  19. Corrugated Shell Displacements During the Passage of a Vehicle Along a Soil-Steel Structure

    NASA Astrophysics Data System (ADS)

    Machelski, Czesław; Mumot, Marcin

    2016-12-01

    Corrugated steel plates are highly rigid and as the constructions can be immersed in soil, they can be used as soil-steel structures. With an increase of cover depth, the effectiveness of operating loads decreases. A substantial reduction of the impacts of vehicles takes place as a road or rail surface with its substructure is crucial. The scope of load's impact greatly exceeds the span L of a shell. This article presents the analysis of deformations of the upper part of a shell caused by a live load. One of the assumptions used in calculations performed in Plaxis software was the circle-shaped shell and the circumferential segment of the building structure in the 2D model. The influence lines of the components of vertical and horizontal displacements of points located at the highest place on the shell were used as a basis of analysis. These results are helpful in assessing the results of measurements carried out for the railway structure during the passage of two locomotives along the track. This type of load is characterized by a steady pressure onto wheels with a regular wheel base. The results of measurements confirmed the regularity of displacement changes during the passage of this load.

  20. Pressure drop testing of corrugated stainless steel pliable gas tubing (PLT)

    NASA Astrophysics Data System (ADS)

    Srinivasan, Bharadwaj

    An experimental program was initiated to determine the Darcy friction factor in straight corrugated stainless steel pliable gas tubing (PLT). Pressure loss tests were conducted on PLT per I.S. EN 15266:2007. A power law least-squares curve fit was used to relate pressure loss per unit length as a function of volume flow rate. The calculated coefficient of determination values for the straight PLT exceeded 0.90 indicating suitable correlation. Darcy friction factors were calculated from test data for each case and plotted on a Moody diagram as a function of Reynolds number based on the minimum PLT cross section. For Reynolds numbers less than 2300 the pressure loss data for PLT yielded an inverse relationship between the Darcy friction factor and the Reynolds number, with a proportionality coefficient of 49. The measurement uncertainty estimates for straight sections was performed with a 95% confidence level. Straight PLT flow rates for air and representative fuel gases that would yield a pressure loss Deltap = 1 mbar were calculated as a function of PLT length and diameter. Fitting pressure loss tests were performed for elbows, tees, and bullhead tees. The loss coefficients were evaluated and tabulated. The calculated coefficient of determination values for the fittings was found to be low. The measurement uncertainty was calculated using the root sum square error method and was found to be very high because of the low flow rates considered in this experiment.

  1. Simulation of the evolution of rail corrugation using a rotating flexible wheelset model

    NASA Astrophysics Data System (ADS)

    Vila, Paloma; Fayos, Juan; Baeza, Luis

    2011-11-01

    This paper presents a simulation tool designed for predicting the wear pattern on the running surface of the rails and for studying the evolution of rail corrugation after thousands of wheelset passages. This simulation tool implements a cyclic track model, a rotating flexible wheelset model, a wheel-rail contact model and a wear model. The vehicle-track system is modelled by using a substructuring technique, by which the vehicle, the rails and the sleepers are treated independently of each other and are coupled by the forces transmitted through the wheel-rail contact and the railpad. The vehicle model takes only account of the wheelset since the sprung masses of the vehicle are not relevant in the frequency range analysed. The wheelset model considers the flexibility of the wheelset and the effects associated with rotation. By using the Campbell diagram, two cases have been identified in which the combined effect of two different modes may give rise to higher wheel-rail contact forces and wear.

  2. Electron beam energy chirp control with a rectangular corrugated structure at the Linac Coherent Light Source

    DOE PAGES

    Zhang, Zhen; Bane, Karl; Ding, Yuantao; ...

    2015-01-30

    In this study, electron beam energy chirp is an important parameter that affects the bandwidth and performance of a linac-based, free-electron laser. In this paper we study the wakefields generated by a beam passing between at metallic plates with small corrugations, and then apply such a device as a passive dechirper for the Linac Coherent Light Source (LCLS) energy chirp control with a multi-GeV and femtosecond electron beam. Similar devices have been tested in several places at relatively low energies (~100 MeV) and with relatively long bunches (> 1ps). In the parameter regime of the LCLS dechirper, with the corrugationmore » size similar to the gap between the plates, the analytical solutions of the wakefields are no longer applicable, and we resort to a field matching program to obtain the wakes. Based on the numerical calculations, we fit the short-range, longitudinal wakes to simple formulas, valid over a large, useful parameter range. Finally, since the transverse wakefields - both dipole and quadrupole-are strong, we compute and include them in beam dynamics simulations to investigate the error tolerances when this device is introduced in the LCLS.« less

  3. On Locally Deformed Stratified Media : Applications To Rough Surfaces And Guided Wave Devices With Corrugated Boundaries

    NASA Astrophysics Data System (ADS)

    Petit, R.; Hugonin, J. P.

    1984-12-01

    In 1977, we published two papers on the diffraction of electromagnetic waves at a locally deformed flat boundary surface and at a locally deformed plane wave-guide. Since this time, an important theoretical and numerical study of locally deformed stratified media has been carried out in our lab. This study has been summarized three years ago in the J.O.S.A. and it has been presented last year as a thesis dissertation. But both the J.O.S.A. paper and the thesis are difficult to read for non specialists because the involved mathematics are rather subtle and, at least, tedious for experimenters. In other words, an important work has been done, which seems to be unknown to most of "practical people". We thought that a SPIE meeting is a good opportunity to cure this regrettable situation. A computer program is now available which probably might be very useful for those working on rough dielectric surfaces and on guided wave devices with corrugated boundaries. We would like to present to engineers the possibilities and the limits of this big computer code called hereafter Program (P)

  4. Improving wet and dry strength properties of recycled old corrugated carton (OCC) pulp using various polymers.

    PubMed

    Hamzeh, Yahya; Sabbaghi, Sanaz; Ashori, Alireza; Abdulkhani, Ali; Soltani, Farshid

    2013-04-15

    In this study, the application of different dosages of low and high molecular weights (MW) of chitosan (Ch), cationic starch (CS) and poly vinyl alcohol (PVA) were systematically investigated using old corrugated carton (OCC) furnishes. Various sequences of above-mentioned polymeric additives were also examined to find out the optimal combination for improving both wet and dry tensile strength. For each treatment, 4 handsheets, each having basis weight of 100 g/m(2), were made. In general, the tensile strength of handsheets was significantly affected by the addition of polymeric agents. The enhancing effect of additives on dry tensile property was much higher than wet condition. The results also showed that the tensile strength of the samples made from OCC furnishes were improved upon the addition of high molecular weight chitosan (ChI) compared to the untreated ones (control). The low MW chitosan did not change the properties of handsheets dramatically. Application of polymeric agents moderately decreased the stretch to rupture, however with increasing dosage the stretch was improved. Sequential addition of used polymers showed that triple application of polymers was beneficial to both dry and wet tensile strength, although the effect was larger for dry. The best results in wet and dry tensile strengths were achieved using sequential of PVA-ChI-CS. Sequential addition of oppositely charged polymers forms a macromolecular layered structure of polyelectrolytes. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Biodegradation of plastics.

    PubMed

    Shimao, M

    2001-06-01

    Widespread studies on the biodegradation of plastics have been carried out in order to overcome the environmental problems associated with synthetic plastic waste. Recent work has included studies of the distribution of synthetic polymer-degrading microorganisms in the environment, the isolation of new microorganisms for biodegradation, the discovery of new degradation enzymes, and the cloning of genes for synthetic polymer-degrading enzymes.

  6. Detecting plastics in seedcotton

    USDA-ARS?s Scientific Manuscript database

    To increase global market share and value the US cotton industry needs to supply cotton lint that is free of contamination. Removing plastic contamination first requires developing a means to detect plastics in seedcotton. This study was conducted to validate a custom Ion Mobility Spectrometer (IM...

  7. Detecting plastics in seedcotton

    USDA-ARS?s Scientific Manuscript database

    The US cotton industry wants to increase market share and value by supplying pure cotton. Removing contamination requires developing a means to detect plastics in seedcotton. This study was conducted to determine if Ion Mobility Spectrometry (IMS) could be used to find small amounts of plastic in ...

  8. Track recording plastic compositions

    NASA Technical Reports Server (NTRS)

    Tarle, Gregory (Inventor)

    1983-01-01

    Improved nuclear track recording plastic compositions are provided which exhibit greatly decreased surface roughness when etched to produce visible tracks of energetic nuclear particles which have passed into and/or through said plastic. The improved compositions incorporate a small quantity of a phthalic acid ester into the major plastic component which is derived from the polymerization of monomeric di-ethylene glycol bis allyl carbonate. Di-substituted phthalic acid esters are preferred as the added component, with the further perference that the ester substituent has a chain length of 2 or more carbon atoms. The inclusion of the phthalic acid ester to an extent of from about 1-2% by weight of the plastic compositions is sufficient to drastically reduce the surface roughness ordinarily produced when the track recording plastic is contacted by etchants.

  9. POLYESTER GLASS PLASTICS FOR SHIPBUILDING,

    DTIC Science & Technology

    POLYESTER PLASTICS , SHIP HULLS), (*SHIP HULLS, POLYESTER PLASTICS ), GLASS TEXTILES, REINFORCING MATERIALS, SHIP STRUCTURAL COMPONENTS, COMPOSITE MATERIALS, PROCESSING, CHEMISTRY, HANDBOOKS, BINDERS, USSR

  10. Reversal of neuromuscular block with sugammadex: a comparison of the corrugator supercilii and adductor pollicis muscles in a randomized dose-response study.

    PubMed

    Yamamoto, S; Yamamoto, Y; Kitajima, O; Maeda, T; Suzuki, T

    2015-08-01

    Neuromuscular monitoring using the corrugator supercilii muscle is associated with a number of challenges. The aim of this study was to assess reversal of a rocuronium-induced neuromuscular blockade with sugammadex according to monitoring either using the corrugator supercilii muscle or the adductor pollicis muscle. We hypothesized that a larger dose of sugammadex would be required to obtain a train-of-four (TOF) ratio of 1.0 with the corrugator supercilii muscle than with the adductor pollicis muscle. Forty patients aged 20-60 years and 40 patients aged ≥ 70 years were enrolled. After induction of anesthesia, we recorded the corrugator supercilii muscle response to facial nerve stimulation and the adductor pollicis muscle response to ulnar nerve stimulation using acceleromyography. All patients received 1 mg/kg rocuronium. When the first twitch (T1) of TOF recovered to 10% of control values at the corrugator supercilii, rocuronium infusion was commenced to maintain a T1 of 10% of the control at the corrugator supercilii. Immediately after discontinuation of rocuronium infusion, 2 mg/kg or 4 mg/kg of sugammadex was administered. The time for recovery to a TOF ratio of 1.0 and the number of patients not reaching a TOF ratio of 1.0 by 5 min at each dose and muscle was recorded. When neuromuscular block at the corrugator supercilii was maintained at a T1 of 10% of control, that at the adductor pollicis was deep (post-tetanic count ≤ 5). Sugammadex 4 mg/kg completely antagonized neuromuscular block at both muscles within 5 min. The time to a TOF ratio of 1.0 at the adductor pollicis was significantly longer in the group ≥ 70 years than the group 20-60 years (mean (SD): 178 (42.8) s vs. 120 (9.4) s, P < 0.0001). In contrast, 2 mg/kg sugammadex reversed neuromuscular blockade at the corrugator supercilii but not at the adductor pollicis, with 10 patients in the group 20-60 years and 8 patients in the group ≥ 70 years requiring an additional

  11. High explosive testing of a corrugated metal blast shelter with membrane blast doors

    SciTech Connect

    Zimmerman, G.P.; Chester, C.V.

    1984-12-01

    In October 1983 the Defense Nuclear Agency (DNA) sponsored a high-explosive blast test, nicknamed DIRECT COURSE. This event simulated the blast effects from a one-kiloton nuclear detonation and provided an environment for the testing of selected blast and fallout shelters for their structural integrity. Under work for the Federal Emergency Management Agency (FEMA), the Oak Ridge National Laboratory (ORNL) fielded a set of experiments at the DIRECT COURSE event which were directed toward reducing the cost of blast shelter for small groups of people, such as workers in critical industries (keyworkers). Six items were tested: three scale models of a corrugated metal blast shelter and three full-size blast door closures for such a shelter. The three shelters survived blast overpressures up to 2.55 MPa (225 psi), a level which is equivalent to being approximately 800 m (0.5 mile) from a 1 megaton nuclear detonation. Each shelter model was 180 cm (6 ft.) long by 60 cm (2 ft.) in diameter, was buried about 60 cm (2 ft.) below ground level, and represented a 1/4-scale version of a full-size blast shelter which would be capable of supporting 12 to 18 occupants. The three full-size, 90 cm (35 in.) diameter, blast doors for such a shelter also successfully resisted the same range of blast overpressure. Each door weighed less than 45 kg (100 lb) and incorporated a novel, yielding-membrane design. These sheet metal membranes were between 1.3 and 2.0 mm (0.050 and 0.080 in.) thick and were supported by an edge beam (hoop).

  12. Mode Content Determination of Terahertz Corrugated Waveguides Using Experimentally Measured Radiated Field Patterns.

    PubMed

    Jawla, Sudheer K; Nanni, Emilio A; Shapiro, Michael A; Woskov, Paul P; Temkin, Richard J

    2012-06-01

    This work focuses on the accuracy of the mode content measurements in an overmoded corrugated waveguide using measured radiated field patterns. Experimental results were obtained at 250 GHz using a vector network analyzer with over 70 dB of dynamic range. The intensity and phase profiles of the fields radiated from the end of the 19 mm diameter helically tapped brass waveguide were measured on planes at 7, 10, and 13 cm from the waveguide end. The measured fields were back propagated to the waveguide aperture to provide three independent estimates of the field at the waveguide exit aperture. Projecting that field onto the modes of the guide determined the waveguide mode content. The three independent mode content estimates were found to agree with one another to an accuracy of better than ±0.3%. These direct determinations of the mode content were compared with indirect measurements using the experimentally measured amplitude in three planes, with the phase determined by a phase retrieval algorithm. The phase retrieval technique using the planes at 7, 10, and 13 cm yielded a mode content estimate in excellent agreement, within 0.3%, of the direct measurements. Phase retrieval results using planes at 10, 20, and 30 cm were less accurate due to truncation of the measurement in the transverse plane. The reported measurements benefited greatly from a precise mechanical alignment of the scanner with respect to the waveguide axis. These results will help to understand the accuracy of mode content measurements made directly in cold test and indirectly in hot test using the phase retrieval technique.

  13. White-Light Emission and Structural Distortion in New Corrugated Two-Dimensional Lead Bromide Perovskites.

    PubMed

    Mao, Lingling; Wu, Yilei; Stoumpos, Constantinos C; Wasielewski, Michael R; Kanatzidis, Mercouri G

    2017-03-29

    Hybrid inorganic-organic perovskites are developing rapidly as high performance semiconductors. Recently, two-dimensional (2D) perovskites were found to have white-light, broadband emission in the visible range that was attributed mainly to the role of self-trapped excitons (STEs). Here, we describe three new 2D lead bromide perovskites incorporating a series of bifunctional ammonium dications as templates which also emit white light: (1) α-(DMEN)PbBr4 (DMEN = 2-(dimethylamino)ethylamine), which adopts a unique corrugated layered structure in space group Pbca with unit cell a = 18.901(4) Å, b = 11.782(2) Å, and c = 23.680(5) Å; (2) (DMAPA)PbBr4 (DMAPA = 3-(dimethylamino)-1-propylamine), which crystallizes in P21/c with a = 10.717(2) Å, b = 11.735(2) Å, c = 12.127(2) Å, and β = 111.53(3)°; and (3) (DMABA)PbBr4 (DMABA = 4-dimethylaminobutylamine), which adopts Aba2 with a = 41.685(8) Å, b = 23.962(5) Å, and c = 12.000(2) Å. Photoluminescence (PL) studies show a correlation between the distortion of the "PbBr6" octahedron in the 2D layer and the broadening of PL emission, with the most distorted structure having the broadest emission (183 nm full width at half-maximum) and longest lifetime (τavg = 1.39 ns). The most distorted member α-(DMEN)PbBr4 exhibits white-light emission with a color rendering index (CRI) of 73 which is similar to a fluorescent light source and correlated color temperature (CCT) of 7863 K, producing "cold" white light.

  14. Mode Content Determination of Terahertz Corrugated Waveguides Using Experimentally Measured Radiated Field Patterns

    PubMed Central

    Jawla, Sudheer K.; Nanni, Emilio A.; Shapiro, Michael A.; Woskov, Paul P.; Temkin, Richard J.

    2012-01-01

    This work focuses on the accuracy of the mode content measurements in an overmoded corrugated waveguide using measured radiated field patterns. Experimental results were obtained at 250 GHz using a vector network analyzer with over 70 dB of dynamic range. The intensity and phase profiles of the fields radiated from the end of the 19 mm diameter helically tapped brass waveguide were measured on planes at 7, 10, and 13 cm from the waveguide end. The measured fields were back propagated to the waveguide aperture to provide three independent estimates of the field at the waveguide exit aperture. Projecting that field onto the modes of the guide determined the waveguide mode content. The three independent mode content estimates were found to agree with one another to an accuracy of better than ±0.3%. These direct determinations of the mode content were compared with indirect measurements using the experimentally measured amplitude in three planes, with the phase determined by a phase retrieval algorithm. The phase retrieval technique using the planes at 7, 10, and 13 cm yielded a mode content estimate in excellent agreement, within 0.3%, of the direct measurements. Phase retrieval results using planes at 10, 20, and 30 cm were less accurate due to truncation of the measurement in the transverse plane. The reported measurements benefited greatly from a precise mechanical alignment of the scanner with respect to the waveguide axis. These results will help to understand the accuracy of mode content measurements made directly in cold test and indirectly in hot test using the phase retrieval technique. PMID:25264391

  15. Transmission Characteristics of Hybrid Modes in Corrugated Waveguides Above the Bragg Frequency

    NASA Astrophysics Data System (ADS)

    Ohkubo, Kunizo; Saito, Teruo; Yamaguchi, Yuusuke; Tatematsu, Yoshinori; Kasa, Jun; Kubo, Shin; Shimozuma, Takashi; Tanaka, Kenji; Nishiura, Masaki

    2017-07-01

    We studied the transmission characteristics of hybrid modes in a corrugated circular waveguide above the Bragg frequency to develop a broad-band transmission line for millimeter waves. Millimeter waves at 294 GHz were transmitted into a straight waveguide. From observed power profiles in waveguide cross-sections, a high attenuation rate of 0.13 dB/m was obtained. To match a theoretical attenuation constant with the experimental one, we introduced an ad hoc coefficient of conventional surface reactance in the waveguide wall. This was necessary because the wall began to look like the surface with a decreasing anisotropic reactance owing to the frequency above the Bragg frequency. Using nonlinear optimization for mode content analysis, the observed power profiles in the waveguide cross-section were matched with theoretical profiles. There was good agreement between the calculated and observed centers of power profiles and attenuation rate along the waveguide. The theoretical analysis showed that the magnetic field at the waveguide wall increases and the substantial attenuation takes place. Above the Bragg frequency coupling to backwards propagating modes is a point of consideration. A combination of the backwards propagating EH1,26 and the forward propagating HE11 modes satisfied the Bragg condition at 294.7 GHz which was the nearest frequency of operating frequency. A strong attenuation of the incoming HE11 mode by Bragg resonance was not expected due to large difference of 0.7 GHz. It becomes clear that the observed high transmission loss outside of the Bragg resonance can be explained by a decrease in anisotropic surface reactance at the wall.

  16. Corrugation-assisted metal-coated angled fiber facet for wavelength-dependent off-axis directional beaming.

    PubMed

    Kim, Hyuntai; An, Haechan; Kim, Jinseob; Lee, Seungsu; Park, Kyoungyoon; Lee, Seungjong; Hong, Seungsoo; Vazquez-Zuniga, Luis Alonso; Lee, Seung-Yeol; Lee, Byoungho; Jeong, Yoonchan

    2017-04-03

    We propose a fiber-optic-plasmonic hybrid device that is based on a corrugation-assisted metal-coated angled fiber facet (CA-MCAFF) for wavelength-dependent off-axis directional beaming (WODB). The device breaks into two key structures: One is the MCAFF structure, which is a modified Kretschmann configuration implemented onto a fiber platform, thereby being able to generate a unidirectional surface plasmon with dramatically enhanced properties in terms of non-confined diffracted radiation loss and operational bandwidth. The other is the periodic corrugation structure put on the MCAFF, thereby enabling WODB functionality out of the whole structures. The corrugated metal surface out-couples the surface plasmon mode to free-space optical radiation into a direction that varies with the wavelength of the optical radiation with excellent linearity. We perform extensive numerical investigations based on the finite-element-method and analyze the out-coupling efficiency (OCEout) and spectral bandwidth (SBout) of the proposed device for various designs and conditions. We determine the seven structural parameters of the device via taking sequential optimization steps. We deduce two optimal conditions particularly for the fiber-facet angle, in terms of the averaged OCEout or the SBout in the whole visible wavelength range (400 - 700 nm), which eventually leads to OCEout = 30.4% and SBout = 230 nm or to OCEout = 24.5% and SBout = 245 nm, respectively. These results suggest substantial enhancements in both OCEout and SBout, in comparison with the performance properties of a typical nano-slit-based device having a similar type of WODB functionality. The proposed CA-MCAFF is a simple, compact and efficient WODB device that is fully compatible with the state-of-the-art optical fiber technology.

  17. A Plastic Menagerie

    ERIC Educational Resources Information Center

    Hadley, Mary Jane

    2010-01-01

    Bobble heads had become quite popular, depicting all sorts of sports figures, animals, and even presidents. In this article, the author describes how her fourth graders made bobble head sculptures out of empty plastic drink bottles. (Contains 1 online resource.)

  18. Shape-Shifting Plastic

    SciTech Connect

    2015-05-20

    A new plastic developed by ORNL and Washington State University transforms from its original shape through a series of temporary shapes and returns to its initial form. The shape-shifting process is controlled through changes in temperature

  19. Dreaming in plastic

    NASA Astrophysics Data System (ADS)

    Korzhov, Marianna; Andelman, David; Shikler, Rafi

    2008-07-01

    Plastic is one of the most versatile materials available. It is cheap, flexible and easy to process, and as a result it is all around us - from our computer keyboards to the soles of our shoes. One of its most common applications is as an insulating coating for electric wires; indeed, plastic is well known for its insulating characteristics. It came as something of a surprise, therefore, when in the late 1970s a new generation of plastics was discovered that displayed exactly the opposite behaviour - the ability to conduct electricity. In fact, plastics can be made with a whole range of conductivities - there are polymer materials that behave like semiconductors and there are those that can conduct as well as metals. This discovery sparked a revolution in the electronics community, and three decades of research effort is now yielding a range of stunning new applications for this ubiquitous material.

  20. Strain avalanches in plasticity

    NASA Astrophysics Data System (ADS)

    Argon, A. S.

    2013-09-01

    Plastic deformation at the mechanism level in all solids occurs in the form of discrete thermally activated individual stress relaxation events. While there are clear differences in mechanisms between dislocation mediated events in crystalline solids and by individual shear transformations in amorphous metals and semiconductors, such relaxation events interact strongly to form avalanches of strain bursts. In all cases the attendant distributions of released energy as amplitudes of acoustic emissions, or in serration amplitudes in flow stress, the levels of strain bursts are of fractal character with fractal exponents in the range from -1.5 to -2.0, having the character of phenomena of self-organized criticality, SOC. Here we examine strain avalanches in single crystals of ice, hcp metals, the jerky plastic deformations of nano-pillars of fcc and bcc metals deforming in compression, those in the plastic flow of bulk metallic glasses, all demonstrating the remarkable universality of character of plastic relaxation events.

  1. A Plastic Menagerie

    ERIC Educational Resources Information Center

    Hadley, Mary Jane

    2010-01-01

    Bobble heads had become quite popular, depicting all sorts of sports figures, animals, and even presidents. In this article, the author describes how her fourth graders made bobble head sculptures out of empty plastic drink bottles. (Contains 1 online resource.)

  2. Mechanical plasticity of cells

    NASA Astrophysics Data System (ADS)

    Bonakdar, Navid; Gerum, Richard; Kuhn, Michael; Spörrer, Marina; Lippert, Anna; Schneider, Werner; Aifantis, Katerina E.; Fabry, Ben

    2016-10-01

    Under mechanical loading, most living cells show a viscoelastic deformation that follows a power law in time. After removal of the mechanical load, the cell shape recovers only incompletely to its original undeformed configuration. Here, we show that incomplete shape recovery is due to an additive plastic deformation that displays the same power-law dynamics as the fully reversible viscoelastic deformation response. Moreover, the plastic deformation is a constant fraction of the total cell deformation and originates from bond ruptures within the cytoskeleton. A simple extension of the prevailing viscoelastic power-law response theory with a plastic element correctly predicts the cell behaviour under cyclic loading. Our findings show that plastic energy dissipation during cell deformation is tightly linked to elastic cytoskeletal stresses, which suggests the existence of an adaptive mechanism that protects the cell against mechanical damage.

  3. Art and Plastic Surgery.

    PubMed

    Fernandes, Julio Wilson; Metka, Susanne

    2016-04-01

    The roots of science and art of plastic surgery are very antique. Anatomy, drawing, painting, and sculpting have been very important to the surgery and medicine development over the centuries. Artistic skills besides shape, volume, and lines perception can be a practical aid to the plastic surgeons' daily work. An overview about the interactions between art and plastic surgery is presented, with a few applications to rhinoplasty, cleft lip, and other reconstructive plastic surgeries. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

  4. Physics in Plastics Technology.

    ERIC Educational Resources Information Center

    Thomas, Ken

    1980-01-01

    Discusses the increasing role of the physicist in plastics technology. Relationships of molecular structure to material behavior, design which is related to the material, and the practical problems of fabricating a material into an article are included. (HM)

  5. Laser cutting plastic materials

    SciTech Connect

    Van Cleave, R.A.

    1980-08-01

    A 1000-watt CO/sub 2/ laser has been demonstrated as a reliable production machine tool for cutting of plastics, high strength reinforced composites, and other nonmetals. More than 40 different plastics have been laser cut, and the results are tabulated. Applications for laser cutting described include fiberglass-reinforced laminates, Kevlar/epoxy composites, fiberglass-reinforced phenolics, nylon/epoxy laminates, ceramics, and disposable tooling made from acrylic.

  6. Chaotic millimeter-wave generation on the basis of wideband gyro-amplifiers with a helical corrugated waveguide

    NASA Astrophysics Data System (ADS)

    Ginzburg, N. S.; Rozental, R. M.; Sergeev, A. S.; Zotova, I. V.

    2017-02-01

    The possibility of generating random noiselike radiation in gyro-amplifiers with a helical corrugated waveguide when introducing delayed feedback has been shown. The cyclotron resonance detuning corresponding to the maximum slope of the amplitude characteristic of an amplifier after saturation is optimal for implementing the mode of developed dynamic chaos. Assessments are carried out for the parameters of a noise generator based on an experimentally implemented gyro-travelling-wave tube of 35-GHz band, according to which the generation of multifrequency radiation is possible with a spectrum width of 3—4 GHz, an average power up to 70 kW, and an efficiency of order of 10%.

  7. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Dependence of Conductance of Corrugated Graphene Quantum Dot on Geometrical Features

    NASA Astrophysics Data System (ADS)

    Li, Gui-Qin; Deng, Jing-Kang; Cai, Jun

    2009-11-01

    Dependence of conductance of corrugated graphene quantum dot (CGQD) on geometrical features including length, width, connection and edge is investigated by the first principles calculations. The results demonstrate that the conductance of CGQD with different geometrical features is different from each other. The positions and amplitudes of discrete levels in densities of states and transmission coefficients are sensitive to geometrical features. The I-V characteristics of graphene are modified by size and edge, it is surprise the current does not change monotonously but oscillatory with length. And they are slight change for different connections.

  8. Corrugated waveguide mode purifier for TEM output in a dual-mode operation overmoded coaxial millimeter-wave generator

    NASA Astrophysics Data System (ADS)

    Bai, Zhen; Zhang, Jun; Zhong, Huihuang; Zhang, Dian

    2017-01-01

    A coaxial corrugated waveguide mode purifier is designed for a dual-mode operation overmoded coaxial millimeter-wave generator. With the purifier, the mixed TEM and TM01 modes output are purified into a pure TEM mode. Particle-in-cell (PIC) simulation shows that the purifier would not decrease the total output power of the generator, and plays an independent role to the upstream structure. Effects of mode composition ratio and phase difference on the purification ability of the purifier are also researched by both electromagnetism and PIC simulations, which show that the purifier has a certain tolerance for both the mode composition ratio and phase difference.

  9. Experimental observation of optical bandgaps for surface electromagnetic waves in a periodically corrugated one-dimensional silicon nitride photonic crystal.

    PubMed

    Descrovi, Emiliano; Giorgis, Fabrizio; Dominici, Lorenzo; Michelotti, Francesco

    2008-02-01

    Dispersion curves of surface electromagnetic waves (SEWs) in 1D silicon nitride photonic crystals having periodic surface corrugations are considered. We experimentally demonstrate that a bandgap for SEWs can be obtained by fabricating a polymeric grating on the multilayered structure. Close to the boundary of the first Brillouin zone connected to the grating, we observe the splitting of the SEW dispersion curve into two separate branches and identify two regions of very low group velocity. The proper design of the structure allows the two folded branches to lie beyond the light line in a wide spectral range, thus doubling the density of modes available for SEWs and avoiding light scattering.

  10. Analysis of brook trout spatial behavior during passage attempts in corrugated culverts using near-infrared illumination video imagery

    USGS Publications Warehouse

    Bergeron, Normand E.; Constantin, Pierre-Marc; Goerig, Elsa; Castro-Santos, Theodore R.

    2016-01-01

    We used video recording and near-infrared illumination to document the spatial behavior of brook trout of various sizes attempting to pass corrugated culverts under different hydraulic conditions. Semi-automated image analysis was used to digitize fish position at high temporal resolution inside the culvert, which allowed calculation of various spatial behavior metrics, including instantaneous ground and swimming speed, path complexity, distance from side walls, velocity preference ratio (mean velocity at fish lateral position/mean crosssectional velocity) as well as number and duration of stops in forward progression. The presentation summarizes the main results and discusses how they could be used to improve fish passage performance in culverts.

  11. Bragg transmittance of s-polarized waves through finite-thickness photonic crystals with a periodically corrugated interface.

    PubMed

    Serebryannikov, A E; Magath, T; Schuenemann, K

    2006-12-01

    Finite-thickness photonic crystals (PC's) with periodically corrugated interfaces are suggested to realize some unusual features in the behavior of transmitted Bragg beams (diffraction orders). The scattering of s -polarized plane waves by such structures is studied. It follows from the numerical results that rather thin corrugated PC's borrow their basic properties from both conventional PC's and gratings, leading to some new effects. In particular, a shift of the actual cutoff frequencies towards larger values than those of the Rayleigh cutoff frequencies can be obtained due to the ordinary opaque range in transmission, within which all propagative orders vanish. This effect can even be enhanced due to the nonordinary behavior arising at the edges of the ordinary opaque range, which manifests itself in that some but not all propagative orders in transmission are suppressed. Hence the opaque ranges for individual orders are wider than the corresponding ordinary range. Besides, frequency ranges exist which are not connected with the edge of the ordinary opaque range, where a similar nonordinary effect does appear. As a result, each propagative order in transmission generally has its own set of opaque ranges. Only a single order can be contributive while several others are formally propagative, too. The corrugations have to be located at the upper interface in order to realize these nonordinary effects. Moving the corrugation from the upper to the lower interface leads to a disappearance of the observed effects, so that their nature cannot be explained exclusively in terms of matching the wave vectors of the diffraction orders and the Floquet-Bloch waves. The conventional sequence of cutoffs for different diffraction orders with respect to each other can be changed for certain structures if the rods of a PC are made of Drude metal. Hence, transmission regimes can be realized which are beyond the classical theory of gratings. Several effects arising when varying the

  12. The Need for Plastics Education.

    ERIC Educational Resources Information Center

    Society of Plastics Engineers, Inc., Stamford, CT.

    In view of a lack of trained personnel in the industry, the Plastics Education Foundation proposes that educators (1) add more plastics programs, (2) establish plastics engineering degrees at appropriate 4-year institutions, (3) add plastics processing technology to current engineering curricula, and (4) interest younger students in courses and/or…

  13. The Need for Plastics Education.

    ERIC Educational Resources Information Center

    Society of Plastics Engineers, Inc., Stamford, CT.

    In view of a lack of trained personnel in the industry, the Plastics Education Foundation proposes that educators (1) add more plastics programs, (2) establish plastics engineering degrees at appropriate 4-year institutions, (3) add plastics processing technology to current engineering curricula, and (4) interest younger students in courses and/or…

  14. Application of WinSRFR4 program to zigzag corrugated furrow irrigation in Bolivia

    NASA Astrophysics Data System (ADS)

    Roldán Cañas, José; Moreno Perez, Maria Fatima; Garcia Moreno, Francisco Javier; Chipana, Rene

    2013-04-01

    Program WinSRFR4, developed by the Agricultural Research Service-U.S. Department of Agriculture, is used to perform surface irrigation evaluations, to establish appropriate irrigation parameters to get better irrigation efficiencies, to execute irrigation simulations and so to set several alternatives to the design of an irrigation. This paper aims to adapt WinSRFR4 program to zigzag corrugated furrow irrigation performed in the Andean regions of Bolivia. These irrigations are quite peculiar as they are carried out in areas with steep slope and with very low flow rates to avoid the risk of erosion. Besides of this, the flow rates are quite variable during the irrigation application. The greater length of the furrows is drawn on contours performing small jumps between consecutive contours. Available data are taken for seven irrigations for different periods of lettuce crop growth. First, a model that fits irrigations executed has been searched. For this, we have conducted a series of tests with the program WinSRFR4, being necessary to carry some simplifications given the peculiarity of this type of irrigation. The procedure consisted in determining the advance curves during irrigation. Later, the parameters of the Kostiakov - Lewis equation have been calculated by the method of Walker and Elliot. Although the furrow longitudinal profile was available, a mean slope was used at the time of establishing the model. WinSRFR provides a model of analyzed irrigation with a coefficient of determination ranged from R2 = 0.3520 to R2 = 0.9095. Finally, the errors obtained in the mass balances are between 2% and 14%. The model showed that application efficiencies ranged between 9% and 35%, rather poor, while runoff coefficients varied between 47% and 91%. Not too much importance is given to the fact that runoff occurs because runoff water is used in plots located at a lower level Irrigation simulations have been carried out using WinSRFR by changing the operation variables

  15. 77 FR 54930 - Carlyle Plastics and Resins, Formerly Known as Fortis Plastics, A Subsidiary of Plastics...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-06

    ... Employment and Training Administration Carlyle Plastics and Resins, Formerly Known as Fortis Plastics, A Subsidiary of Plastics Acquisitions Inc., Including On-Site Leased Workers From Kelly Services and Shelley... Adjustment Assistance on July 3, 2012, applicable to workers and former workers of workers of Fortis Plastics...

  16. Effect of surface corrugation on low temperature phases of adsorbed (p-H2)7: A quantum path integral Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Cruz, Anthony; López, Gustavo E.

    2014-04-01

    By using path integral Monte Carlo simulations coupled to Replica Exchange algorithms, various phases of (p-H2)7 physically adsorbed on a model graphite surface were identified at low temperatures. At T=0.5 K, the expected superfluid phase was observed for flat and slightly corrugated surfaces. At intermediate and high corrugations, a "supersolid" phase in C7/16 registry and a solid phase in C1/3 registry were observed, respectively. At higher temperatures, the superfluid is converted to a fluid and the "supersolid" to a solid.

  17. Cooling Performance and Structural Reliability of a Modified Corrugated-insert Air-cooled Turbine Blade with an Integrally Cast Shell and Base

    NASA Technical Reports Server (NTRS)

    Freche, John C; Schum, Eugene F

    1957-01-01

    A modified corrugated-insert blade with integrally cast shell and base was developed. This blade was as light as a conventional fabricated corrugated-insert blade. Of four test blades operated in a full-scale turbojet engine, one failed after about 15 hours operation at an inlet gas temperature of 1670 degrees F, a coolant-flow ratio of 0.0064, and a 1/3-span centrifugal stress of approximately 28,000 psi. Three other test blades ran for approximately 16, 31, and 36 hours without failure at similar conditions.

  18. Rigorous electromagnetic analysis of dipole emission in periodically corrugated layers: the grating-assisted resonant-cavity light-emitting diode.

    PubMed

    Delbeke, Danaë; Bienstman, Peter; Bockstaele, Ronny; Baets, Roel

    2002-05-01

    We study the grating-assisted light-emitting diode, an LED design for high brightness based on a resonant cavity containing one- or two-dimensionally periodically corrugated layers (grating). We give in detail a generally applicable electromagnetic analysis based on the rigorous coupled-wave theory to calculate the extraction efficiency of spontaneous emission in a periodically corrugated layer structure. This general model is then specified on the grating-assisted resonant-cavity LED, showing simulated efficiencies of more than 40%.

  19. Thermo-fluid characteristics of laminar flow of viscous oil through a circular tube having integral helical corrugations and fitted with centre-cleared twisted-tape

    NASA Astrophysics Data System (ADS)

    Saha, Sujoy Kumar; Dayanidhi, G. L.

    2012-12-01

    The experimental friction factor and Nusselt number data for laminar flow through a circular duct having integral helical corrugation and fitted with centre-cleared twisted-tape has been presented. Predictive friction factor and Nusselt number correlations have also been presented. The thermohydraulic performance has been evaluated. The major findings of this experimental investigation are that the centre-cleared twisted tapes in combination with integral helical corrugation perform better than the individual enhancement technique acting alone for laminar flow through a circular duct up to a certain amount of twisted-tape centre-clearance.

  20. Experimental investigation of laminar flow of viscous oil through a circular tube having integral axial corrugation roughness and fitted with twisted tapes with oblique teeth

    NASA Astrophysics Data System (ADS)

    Pal, Sagnik; Saha, Sujoy Kumar

    2015-08-01

    The experimental friction factor and Nusselt number data for laminar flow of viscous oil through a circular duct having integral axial corrugation roughness and fitted with twisted tapes with oblique teeth have been presented. Predictive friction factor and Nusselt number correlations have also been presented. The thermohydraulic performance has been evaluated. The major findings of this experimental investigation are that the twisted tapes with oblique teeth in combination with integral axial corrugation roughness perform significantly better than the individual enhancement technique acting alone for laminar flow through a circular duct up to a certain value of fin parameter.

  1. How do bendy straws bend? A study of re-configurability of multi-stable corrugated shells

    NASA Astrophysics Data System (ADS)

    Bende, Nakul; Selden, Sarah; Evans, Arthur; Santangelo, Christian; Hayward, Ryan

    Shape programmable systems have evolved to allow for reconfiguration of structures through a variety of mechanisms including swelling, stress-relaxation, and thermal expansion. Particularly, there has been a recent interest in systems that exhibit bi-stability or multi-stability to achieve transformation between two or more pre-programmed states. Here, we study the ubiquitous architecture of corrugated shells, such as drinking straws or bellows, which has been well known for centuries. Some of these structures exhibit almost continuous stability amongst a wide range of reconfigurable shapes, but the underlying mechanisms are not well understood. To understand multi-stability in `bendy-straw' structures, we study the unit bi-conical segment using experiments and finite element modeling to elucidate the key geometrical and mechanical factors responsible for its multi-stability. The simple transformations of a unit segment - a change in length or angle can impart complex re-configurability of a structure containing many of these units. The fundamental understanding provided of this simple multi-stable building block could yield improvements in shape re-configurability for a wide array of applications such as corrugated medical tubing, robotics, and deployable structures. NSF EFRI ODISSEI-1240441.

  2. Corrugated-Diaphragm Based Fiber Laser Hydrophone with Sub-100 μPa/Hz1/2 Resolution

    PubMed Central

    Yang, Wen-Zhao; Jin, Long; Liang, Yi-Zhi; Ma, Jun; Guan, Bai-Ou

    2017-01-01

    In this work, a beat-frequency encoded fiber laser hydrophone is developed for high-resolution acoustic detection by using an elastic corrugated diaphragm. The diaphragm is center-supported by the fiber. Incident acoustic waves deform the diaphragm and induce a concentrated lateral load on the laser cavity. The acoustically induced perturbation changes local optical phases and frequency-modulates the radio-frequency beat signal between two orthogonal lasing modes of the cavity. Theoretical analysis reveals that a higher corrugation-depth/thickness ratio or larger diaphragm area can provide higher transduction efficiency. The experimentally achieved average sensitivity in beat-frequency variation is 185.7 kHz/Pa over a bandwidth of 1 kHz. The detection capability can be enhanced by shortening the cavity length to enhance the signal-to-noise ratio. The minimum detectable acoustic pressure reaches 74 µPa/Hz1/2 at 1 kHz, which is comparable to the zeroth order sea noise. PMID:28587116

  3. A secondary diffraction effect and the generation of Scholte-Stoneley acoustic wave on periodically corrugated surface

    NASA Astrophysics Data System (ADS)

    Liu, Jingfei; Declercq, Nico F.

    2016-05-01

    When a wideband sound beam is incident onto a periodically corrugated surface, a series of diffraction related phenomena can occur. In this work, we report the observation of a secondary diffraction, which is different from those previously investigated. The search of the physical origin of this newly observed diffraction leads to the discovery of the possibility of generating Scholte-Stoneley waves, inspired by Guo, Margetan, and Thompson's work in sound backscattering from rough surfaces, through a nonconventional energy conversion mechanism: direct coupling of the incident energy with the periodic interface. This mechanism allows for the Scholte-Stoneley wave generation at any angle of incidence, which distinguishes it from the well-known energy conversion mechanism of the diffraction-related phenomena such as acoustic Wood anomaly and backward displacement in which wave generation is highly angle dependent. The findings of this work not only enrich the understanding of the interaction of sound with periodically corrugated structures but also provide a new surface wave generation method for the potential applications in nondestructive evaluation of materials.

  4. A secondary diffraction effect and the generation of Scholte–Stoneley acoustic wave on periodically corrugated surface

    SciTech Connect

    Liu, Jingfei; Declercq, Nico F.

    2016-05-07

    When a wideband sound beam is incident onto a periodically corrugated surface, a series of diffraction related phenomena can occur. In this work, we report the observation of a secondary diffraction, which is different from those previously investigated. The search of the physical origin of this newly observed diffraction leads to the discovery of the possibility of generating Scholte–Stoneley waves, inspired by Guo, Margetan, and Thompson's work in sound backscattering from rough surfaces, through a nonconventional energy conversion mechanism: direct coupling of the incident energy with the periodic interface. This mechanism allows for the Scholte–Stoneley wave generation at any angle of incidence, which distinguishes it from the well-known energy conversion mechanism of the diffraction-related phenomena such as acoustic Wood anomaly and backward displacement in which wave generation is highly angle dependent. The findings of this work not only enrich the understanding of the interaction of sound with periodically corrugated structures but also provide a new surface wave generation method for the potential applications in nondestructive evaluation of materials.

  5. Evaluation of Fatigue Strength Improvement by CFRP Laminates and Shot Peening onto the Tension Flanges Joining Corrugated SteelWebs.

    PubMed

    Wang, Zhi-Yu; Wang, Qing-Yuan; Liu, Yong-Jie

    2015-08-19

    Corrugated steel web with inherent high out-of-plane stiffness has a promising application in configuring large span highway bridge girders. Due to the irregularity of the configuration details, the local stress concentration poses a major fatigue problem for the welded flange plates of high strength low alloy structural steels. In this work, the methods of applying CFRP laminate and shot peening onto the surfaces of the tension flanges were employed with the purpose of improving the fatigue strength of such configuration details. The effectiveness of this method in the improvement of fatigue strength has been examined experimentally. Test results show that the shot peening significantly increases hardness and roughness in contrast to these without treatment. Also, it has beneficial effects on the fatigue strength enhancement when compared against the test data of the joints with CFRP strengthening. The stiffness degradation during the loading progress is compared with each treatment. Incorporating the stress acting on the constituent parts of the CFRP laminates, a discussion is made regarding the mechanism of the retrofit and related influencing factors such as corrosion and economic cost. This work could enhance the understanding of the CFRP and shot peening in repairing such welded details and shed light on the reinforcement design of welded joints between corrugated steel webs and flange plates.

  6. Evaluation of Fatigue Strength Improvement by CFRP Laminates and Shot Peening onto the Tension Flanges Joining Corrugated Steel Webs

    PubMed Central

    Wang, Zhi-Yu; Wang, Qing-Yuan; Liu, Yong-Jie

    2015-01-01

    Corrugated steel web with inherent high out-of-plane stiffness has a promising application in configuring large span highway bridge girders. Due to the irregularity of the configuration details, the local stress concentration poses a major fatigue problem for the welded flange plates of high strength low alloy structural steels. In this work, the methods of applying CFRP laminate and shot peening onto the surfaces of the tension flanges were employed with the purpose of improving the fatigue strength of such configuration details. The effectiveness of this method in the improvement of fatigue strength has been examined experimentally. Test results show that the shot peening significantly increases hardness and roughness in contrast to these without treatment. Also, it has beneficial effects on the fatigue strength enhancement when compared against the test data of the joints with CFRP strengthening. The stiffness degradation during the loading progress is compared with each treatment. Incorporating the stress acting on the constituent parts of the CFRP laminates, a discussion is made regarding the mechanism of the retrofit and related influencing factors such as corrosion and economic cost. This work could enhance the understanding of the CFRP and shot peening in repairing such welded details and shed light on the reinforcement design of welded joints between corrugated steel webs and flange plates. PMID:28793509

  7. Exercise and cerebrovascular plasticity.

    PubMed

    Nishijima, T; Torres-Aleman, I; Soya, H

    2016-01-01

    Aging impairs cerebrovascular plasticity and subsequently leads cerebral hypoperfusion, which synergistically accelerates aging-associated cognitive dysfunction and neurodegenerative diseases associated with impaired neuronal plasticity. On the other hand, over two decades of researches have successfully demonstrated that exercise, or higher level of physical activity, is a powerful and nonpharmacological approach to improve brain function. Most of the studies have focused on the neuronal aspects and found that exercise triggers improvements in neuronal plasticity, such as neurogenesis; however, exercise can improve cerebrovascular plasticity as well. In this chapter, to understand these beneficial effects of exercise on the cerebral vasculature, we first discuss the issue of changes in cerebral blood flow and its regulation during acute bouts of exercise. Then, how regular exercise improves cerebrovascular plasticity will be discussed. In addition, to shed light on the importance of understanding interactions between the neuron and cerebral vasculature, we describe neuronal activity-driven uptake of circulating IGF-I into the brain. © 2016 Elsevier B.V. All rights reserved.

  8. The plasticity of clays

    USGS Publications Warehouse

    Group, F.F.

    1905-01-01

    (1) Sand injures plasticity little at first because the grains are suspended in a plastic mass. It is only when grains are abundant enough to come in contact with their neighbors, that the effect becomes serious, and then both strength and amount of possible flow are injured. (2) Certain rare organic colloids increase the plasticity by rendering the water viscous. (3) Fineness also tends to increase plasticity. (4) Plane surfaces (plates) increase the amount of possible flow. They also give a chance for lubrication by thinner films, thus increasing the friction of film, and the strength of the whole mass. The action of plates is thus twofold ; but fineness may be carried to such an extent as to break up plate-like grains into angular fragments. The beneficial effects of plates are also decreased by the fact that each is so closely surrounded by others in the mass. (5) Molecular attraction is twofold in increasing plasticity. As the attraction increases, the coherence and strength of the mass increase, and the amount of possible deformation before crumbling also increases. Fineness increases this action by requiring more water. Colloids and crystalloids in solution may also increase the attraction. It is thus seen to be more active than any other single factor.

  9. Liquid Metal Droplet and Micro Corrugated Diaphragm RF-MEMS for reconfigurable RF filters

    NASA Astrophysics Data System (ADS)

    Irshad, Wasim

    detail and have proved pivotal to this work. The second part of the dissertation focuses on the Liquid Metal Droplet RF-MEMS. A novel tunable RF MEMS resonator that is based upon electrostatic control over the morphology of a liquid metal droplet (LMD) is conceived. We demonstrate an LMD evanescent-mode cavity resonator that simultaneously achieves wide analog tuning from 12 to 18 GHz with a measured quality factor of 1400-1840. A droplet of 250-mum diameter is utilized and the applied bias is limited to 100 V. This device operates on a principle called Electro-Wetting On Dielectric (EWOD). The liquid metal employed is a non-toxic eutectic alloy of Gallium, Indium and Tin known as Galinstan. This device also exploits interfacial surface energy and viscous body forces that dominate at nanoliter scale. We then apply our Liquid Metal Droplet (LMD) RF-MEMS architecture to demonstrate a continuously tunable electrostatic Ku-Band Filter. A 2-pole bandpass filter with measured insertion loss of less than 0.4dB and 3dB FBW of 3.4% is achieved using a Galinstan droplet of 250mum diameter and bias limited to 100V. We demonstrate that the LMD is insensitive to gravity by performing inversion and tilt experiments. In addition, we study its thermal tolerance by subjecting the LMD up to 150° C. The third part of the dissertation is dedicated to the Micro-Corrugated Diaphragm (MCD) RF-MEMS. We present an evanescent-mode cavity bandpass filter with state-of-the-art RF performance metrics like 4:1 tuning ratio from 5 to 20 GHz with less than 2dB insertion loss and 2-6% 3dB bandwidth. Micro-Corrugated Diaphragm (MCD) is a novel electrostatic MEMS design specifically engineered to provide large-scale analog deflections necessary for such continuous and wide tunable filtering with very high quality factor. We demonstrate a 1.25mm radius and 2mum thick Gold MCD which provides 30mum total deflection with nearly 60% analog range. We also present a detailed and systematic MCD design

  10. Consumer hazards of plastics.

    PubMed Central

    Wiberg, G S

    1976-01-01

    The modern consumer is exposed to a wide variety of plastic and rubber products in his day to day life: at home, work, school, shopping, recreation and play, and transport. A large variety of toxic sequellae have resulted from untoward exposures by many different routes: oral, dermal, inhalation, and parenteral. Toxic change may result from the plastic itself, migration of unbound components and additives, chemical decomposition or toxic pyrolysis products. The type of damage may involve acute poisoning, chronic organ damage, reproductive disorders, and carcinogenic, mutagenic and teratogenic episodes. Typical examples for all routes are cited along with the activites of Canadian regulatory agencies to reduce both the incidence and severity of plastic-induced disease. PMID:1026409

  11. Corrugation in the Weakly Interacting Hexagonal-BN/Cu(111) System: Structure Determination by Combining Noncontact Atomic Force Microscopy and X-ray Standing Waves.

    PubMed

    Schwarz, Martin; Riss, Alexander; Garnica, Manuela; Ducke, Jacob; Deimel, Peter S; Duncan, David A; Thakur, Pardeep Kumar; Lee, Tien-Lin; Seitsonen, Ari Paavo; Barth, Johannes V; Allegretti, Francesco; Auwärter, Willi

    2017-09-26

    Atomically thin hexagonal boron nitride (h-BN) layers on metallic supports represent a promising platform for the selective adsorption of atoms, clusters, and molecular nanostructures. Specifically, scanning tunneling microscopy (STM) studies revealed an electronic corrugation of h-BN/Cu(111), guiding the self-assembly of molecules and their energy level alignment. A detailed characterization of the h-BN/Cu(111) interface including the spacing between the h-BN sheet and its support-elusive to STM measurements-is crucial to rationalize the interfacial interactions within these systems. To this end, we employ complementary techniques including high-resolution noncontact atomic force microscopy, STM, low-energy electron diffraction, X-ray photoelectron spectroscopy, the X-ray standing wave method, and density functional theory. Our multimethod study yields a comprehensive, quantitative structure determination including the adsorption height and the corrugation of the sp(2) bonded h-BN layer on Cu(111). Based on the atomic contrast in atomic force microscopy measurements, we derive a measurable-hitherto unrecognized-geometric corrugation of the h-BN monolayer. This experimental approach allows us to spatially resolve minute height variations in low-dimensional nanostructures, thus providing a benchmark for theoretical modeling. Regarding potential applications, e.g., as a template or catalytically active support, the recognition of h-BN on Cu(111) as a weakly bonded and moderately corrugated overlayer is highly relevant.

  12. A finite element study on rail corrugation based on saturated creep force-induced self-excited vibration of a wheelset-track system

    NASA Astrophysics Data System (ADS)

    Chen, G. X.; Zhou, Z. R.; Ouyang, H.; Jin, X. S.; Zhu, M. H.; Liu, Q. Y.

    2010-10-01

    The present work proposes friction coupling at the wheel-rail interface as the mechanism for formation of rail corrugation. Stability of a wheelset-track system is studied using the finite element complex eigenvalue method. Two models for a wheelset-track system on a tight curved track and on a straight track are established. In these two models, motion of the wheelset is coupled with that of the rail by friction. Creep force at the interface is assumed to become saturated and approximately equal to friction force, which is equal to the normal contact force multiplied by dynamic coefficient of friction. The rail is supported by vertical and lateral springs and dampers at the positions of sleepers. Numerical results show that there is a strong propensity of self-excited vibration of the wheelset-track system when the friction coefficient is larger than 0.21. Some unstable frequencies fall in the range 60-1200 Hz, which correspond to frequencies of rail corrugation. Parameter sensitivity analysis shows that the dynamic coefficient of friction, spring stiffness and damping of the sleeper supports all have important influences on the rail corrugation formation. Bringing the friction coefficient below a certain level can suppress or eliminate rail corrugation.

  13. Anomalous magnetotransport properties of a ballistic non-interacting three-dimensional electron gas confined to narrow potential wells with corrugated barriers

    SciTech Connect

    Sotomayor, N. M.; Davila, L. Y. D.; Lima, B. C.; Gusev, G. M.

    2013-12-04

    The classical dynamics of ballistic non-interacting electrons confined to a narrow electrostatic potential well with corrugated barriers in uniform magnetic field was numerically studied. Trajectories in phase space were analyzed and longitudinal and transversal resistivities were calculated. Commensurability oscillations and negative magnetoresistance similar to those found in antidot lattice devices were observed.

  14. Tug-of-war between corrugation and binding energy: revealing the formation of multiple moiré patterns on a strongly interacting graphene-metal system.

    PubMed

    Martín-Recio, A; Romero-Muñiz, C; Martínez-Galera, A J; Pou, P; Pérez, R; Gómez-Rodríguez, J M

    2015-07-14

    The formation of multidomain epitaxial graphene on Rh(111) under ultra-high vacuum (UHV) conditions has been characterized by scanning tunnelling microscopy (STM) measurements and density functional theory (DFT) calculations. At variance with the accepted view for strongly interacting graphene-metal systems, we clearly demonstrate the formation of different rotational domains leading to multiple moiré structures with a wide distribution of surface periodicities. Experiments reveal a correlation between the STM apparent corrugation and the lattice parameter of the moiré unit cell, with corrugations of just 30-40 pm for the smallest moirés. DFT calculations for a relevant selection of these moiré patterns show much larger height differences and a non-monotonic behaviour with the moiré size. Simulations based on non-equilibrium Green's function (NEGF) methods reproduce quantitatively the experimental trend and provide a detailed understanding of the interplay between electronic and geometric contributions in the STM contrast of graphene systems. Our study sheds light on the subtle energy balance among strain, corrugation and binding that drives the formation of the moiré patterns in all graphene/metal systems and suggests an explanation for the success of an effective model only based on the lattice mismatch. Although low values of the strain energy are a necessary condition, it is the ability of graphene to corrugate in order to maximize the areas of favourable graphene-metal interactions that finally selects the stable configurations.

  15. Plastics in Perspective.

    ERIC Educational Resources Information Center

    Bergandine, David R.; Holm, D. Andrew

    The materials in this curriculum supplement, developed for middle school or high school science classes, present solid waste problems related to plastics. The set of curriculum materials is divided into two units to be used together or independently. Unit I begins by comparing patterns in solid waste from 1960 to 1990 and introducing methods for…

  16. Preserving in Plastic.

    ERIC Educational Resources Information Center

    Wahla, James

    1985-01-01

    Outlines steps for casting insects in permanent molds prepared from commercially available liquid plastic. Also describes dry mountings in glass, acrylic, and petri dishes. The rationale for specimen use, hints for producing quality results, purchasing information, and safety precautions are considered. (DH)

  17. Hydrodynamic Elastic Magneto Plastic

    SciTech Connect

    Wilkins, M. L.; Levatin, J. A.

    1985-02-01

    The HEMP code solves the conservation equations of two-dimensional elastic-plastic flow, in plane x-y coordinates or in cylindrical symmetry around the x-axis. Provisions for calculation of fixed boundaries, free surfaces, pistons, and boundary slide planes have been included, along with other special conditions.

  18. New plastic recycling technology

    EPA Science Inventory

    Greater than 60% of the total plastic content of municipal solid waste is comprised of polyolefins (high-density, low-density, and linear polyethylene and polypropylene. Polyethylene (PE) is the largest-volume component but presents a challenge due to the absence of low-energy de...

  19. The effect of corrugation on the quantum dynamics of dissociative and diffractive scattering of H2 from Pt(111)

    NASA Astrophysics Data System (ADS)

    Pijper, E.; Kroes, G. J.; Olsen, R. A.; Baerends, E. J.

    2000-11-01

    We present results of two dimensional (2D) and three dimensional (3D) calculations for dissociative and diffractive scattering of H2 from Pt(111), using a potential energy surface obtained from density functional theory (DFT) employing the generalized gradient approximation (GGA) in conjunction with a slab representation of the metal surface. The present study is motivated by the importance of Pt as a hydrogenation catalyst, and by a paradox regarding the amount of corrugation of the H2+Pt(111) potential energy surface (PES). Molecular beam experiments on dissociation of D2 from a Pt(111) surface suggest a rather corrugated PES, which is at odds with results from molecular beam experiments on rotationally inelastic diffraction of HD from Pt(111), where only very little diffraction is found, suggesting a weakly corrugated PES. Results of our 3D calculations for off-normal incidence show that the present 3D model does not obey normal energy scaling, and that parallel motion inhibits dissociation at low collision energies, in agreement with the dissociation experiment. On the other hand, substantial diffraction is found, where the diffraction experiment found almost none. For each impact site considered in the 2D calculations, the computed dynamical barrier height, E0, is substantially lower than the barrier height in the PES, Eb, at that site. Both the 2D and the 3D calculations show a large vibrational enhancement of reaction. These effects are not due to a reduced mass effect, the barrier to dissociation being early, but to a decrease in the force constant of the H2 vibration upon approaching the barrier to dissociative adsorption from the gas phase. The vibrational enhancement computed for H2+Pt(111) was not observed in seeded beam experiments on D2+Pt(111) [A. C. Luntz, J. K. Brown, and M. D. Williams, J. Chem. Phys. 93, 5240 (1990)]. However, an analysis performed here strongly suggests that seeded beam experiments will be unable to observe vibrational

  20. American Society of Plastic Surgeons

    MedlinePlus

    ... PRS PRS GO PSN PSEN GRAFT Contact Us Cosmetic Surgery New procedures and advanced technologies offer plastic ... a board-certified plastic surgeon to perform your cosmetic or reconstructive surgery. ASPS member surgeons have the ...

  1. [Anesthetic circle system failure caused by a plastic film--a case report].

    PubMed

    Hara, Naoki; Tanaka, Tomohiro; Minami, Toshiaki

    2006-02-01

    A 44-year-old woman, ASA I, with breast cancer was scheduled for mastectomy. The anesthetic induction was performed by inhalation of 5% sevoflurane and 66% nitrous oxide in oxygen. After the loss of eyelash reflex assisted ventilation was initiated. At this point, the capnograph indicated inspired carbon dioxide tension of 18mmHg. Anesthetic machine check was soon carried out again. A visual check of non-return valves detected a plastic film, 18 x 21mm large, caught in the expiratory valve. This plastic film impaired complete occlusion of the orifice for the expiratory gas flow. As a result, the patient was rebreathing carbon dioxide. After removing it, the wave form of the capnograph was normalized and end-tidal carbon dioxide tension decreased immediately from 45mmHg to 33mmHg. As we did not detect any foreign matters at the non-return valves on anesthetic machine check before use, the plastic film might have already existed in the disposable corrugated tube before use. The capnograph is a useful device for detecting anesthetic circle system failure in such a case. It is important that the patients' airway is separated from the anesthetic circle system through the use of a filter to prevent foreign matter from being inhaled.

  2. Plastics for Elementary School Children

    ERIC Educational Resources Information Center

    Hanson, Jack

    1977-01-01

    Describes three plastics projects (which involve making a styrene fishing bobber, an acrylic salad fork and spoon set, and acetate shrink art) designed to provide elementary level students an opportunity to work with plastics and to learn about careers in plastics production and distribution. (TA)

  3. Plastics for Elementary School Children

    ERIC Educational Resources Information Center

    Hanson, Jack

    1977-01-01

    Describes three plastics projects (which involve making a styrene fishing bobber, an acrylic salad fork and spoon set, and acetate shrink art) designed to provide elementary level students an opportunity to work with plastics and to learn about careers in plastics production and distribution. (TA)

  4. Enhanced efficiency of organic light-emitting devices with corrugated nanostructures based on soft nano-imprinting lithography

    NASA Astrophysics Data System (ADS)

    Liu, Yue-Feng; An, Ming-Hui; Zhang, Xu-Lin; Bi, Yan-Gang; Yin, Da; Zhang, Yi-Fan; Feng, Jing; Sun, Hong-Bo

    2016-11-01

    An enhanced efficiency organic light-emitting device (OLED) with corrugated nanostructures on a small-molecule organic film has been demonstrated. By patterning the hole transport layer via soft nano-imprinting lithography and coating with Ag, a nanostructured cathode is introduced to enhance the light extraction of the OLED without affecting the flatness and conductivity of the indium-tin-oxide film. Both luminance and current efficiency are improved compared with those of conventional planar devices. The observable improvement in luminance and current efficiency can be ascribed to the surface plasmonic and scattering effects caused by the Ag nanostructures. Moreover, theoretical simulations also demonstrate that the power loss to surface plasmon-polariton modes has been recovered.

  5. Constraints on non-Newtonian gravity from measuring the Casimir force in a configuration with nanoscale rectangular corrugations

    SciTech Connect

    Bezerra, V. B.; Romero, C.; Klimchitskaya, G. L.; Mostepanenko, V. M.

    2011-04-01

    We report constraints on the parameters of Yukawa-type corrections to Newtonian gravity from measurements of the gradient of the Casimir force in the configuration of an Au-coated sphere above a Si plate covered with corrugations of trapezoidal shape. For this purpose, the exact expression for the gradient of Yukawa force in the experimental configuration is derived and compared with that obtained using the proximity force approximation. The reported constraints are of almost the same strength as those found previously from several different experiments on the Casimir force and extend over a wide interaction range from 30 to 1260 nm. It is discussed how to make them stronger by replacing the material of the plate.

  6. Narrow linewidth 1560 nm InGaAsP split-contact corrugated ridge waveguide DFB lasers.

    PubMed

    Dridi, Kais; Benhsaien, Abdessamad; Zhang, Jessica; Hall, Trevor J

    2014-11-01

    We demonstrate a split-contact corrugated ridge waveguide InGaAsP distributed feedback laser at 1560 nm. The laser cavity has been defined with uniform third-order gratings etched along the sidewalls of the ridge waveguide. The gratings were fabricated using a standard I-line stepper lithography technique along with an inductively coupled reactive ion-etching process. Stable single-mode operation has been achieved with side-mode suppression ratios ≥50  dB, output powers ≥7  mW, a wavelength tuning range ≥2.3  nm, and narrow linewidths (≤140  kHz) for different biasing conditions, with a minimum of 70 kHz. The effect of p-contact partition on device performance is also studied.

  7. As-pressure influence on the surface corrugation in the homoepitaxial growth of GaAs (6 3 1)A

    NASA Astrophysics Data System (ADS)

    Cruz-Hernández, E.; Shimomura, S.; López-López, M.; Vázquez-Cortes, D.; Méndez-García, V. H.

    2011-02-01

    The achievement of defect-free and highly uniform semiconductor quantum wires is a projected goal with many potential applications. In this article, we report on the homoepitaxy of GaAs on (6 3 1)A-oriented substrates grown by molecular beam epitaxy (MBE) as a function of the As 4 pressure ( PAs). By finding the optimal growth conditions that allow the minimization of intrinsic surface free energy on the substrate and the PAs value, which results in the optimal adatoms diffusion, we were able to realize the outstanding formation of a periodic array of parallel straight nano facets. An analysis of the autocorrelation function is presented, which can be used to quantitatively describe the periodic surface corrugation, and to investigate the optimal growth conditions. We review the thermodynamic and kinetic factors that contribute to the faceting process and discuss how, by reducing the kinetic influence in the growth process, we can promote homogeneous faceting on high-index substrates.

  8. Propagation of thickness shear waves in a periodically corrugated quartz crystal plate and its application exploration in acoustic wave filters.

    PubMed

    Li, Peng; Cheng, Li

    2017-02-07

    The propagation of thickness shear waves in a periodically corrugated quartz crystal plate is investigated in the present paper using a power series expansion technique. In the proposed simulation model, an equivalent continuity of shear stress moment is introduced as an approximation to handle sectional interfaces with abrupt thickness changes. The Bloch theory is applied to simulate the band structures for three different thickness variation patterns. It is shown that the power series expansion method exhibits good convergence and accuracy, in agreement with results by finite element method (FEM). A broad stop band can be obtained in the power transmission spectra owing to the trapped thickness shear modes excited by the thickness variation, whose physical mechanism is totally different from the well-known Bragg scattering effect and is insensitive to the structural periodicity. Based on the observed energy trapping phenomenon, an acoustic wave filter is proposed in a quartz plate with sectional decreasing thickness, which inhibits wave propagation in different regions.

  9. A QSPR for the plasticization efficiency of polyvinylchloride plasticizers.

    PubMed

    Chandola, Mridula; Marathe, Sujata

    2008-01-01

    A simple quantitative structure property relationship (QSPR) for correlating the plasticization efficiency of 25 polyvinylchloride (PVC) plasticizers was obtained using molecular modeling. The plasticizers studied were-aromatic esters (phthalate, terephthalate, benzoate, trimellitate), aliphatic esters (adipate, sebacate, azelate), citrates and a phosphate. The low temperature flex point, Tf, of plasticized polyvinylchloride resins was considered as an indicator of plasticization efficiency. Initially, we attempted to predict plasticization efficiency of PVC plasticizers from physical and structural descriptors derived from the plasticizer molecule alone. However, the correlation of these descriptors with Tf was not very good with R=0.78 and r2=0.613. This implied that the selected descriptors were unable to predict all the interactions between PVC and plasticizer. Hence, to account for these interactions, a model containing two polyvinylchloride (PVC) chain segments along with a plasticizer molecule in a simulation box was constructed, using molecular mechanics. A good QSPR equation correlating physical and structural descriptors derived from the model to Tf of the plasticized resins was obtained with R=0.954 and r2=0.909.

  10. In Your Face: Risk of Punishment Enhances Cognitive Control and Error-Related Activity in the Corrugator Supercilii Muscle.

    PubMed

    Lindström, Björn R; Mattsson-Mårn, Isak Berglund; Golkar, Armita; Olsson, Andreas

    2013-01-01

    Cognitive control is needed when mistakes have consequences, especially when such consequences are potentially harmful. However, little is known about how the aversive consequences of deficient control affect behavior. To address this issue, participants performed a two-choice response time task where error commissions were expected to be punished by electric shocks during certain blocks. By manipulating (1) the perceived punishment risk (no, low, high) associated with error commissions, and (2) response conflict (low, high), we showed that motivation to avoid punishment enhanced performance during high response conflict. As a novel index of the processes enabling successful cognitive control under threat, we explored electromyographic activity in the corrugator supercilii (cEMG) muscle of the upper face. The corrugator supercilii is partially controlled by the anterior midcingulate cortex (aMCC) which is sensitive to negative affect, pain and cognitive control. As hypothesized, the cEMG exhibited several key similarities with the core temporal and functional characteristics of the Error-Related Negativity (ERN) ERP component, the hallmark index of cognitive control elicited by performance errors, and which has been linked to the aMCC. The cEMG was amplified within 100 ms of error commissions (the same time-window as the ERN), particularly during the high punishment risk condition where errors would be most aversive. Furthermore, similar to the ERN, the magnitude of error cEMG predicted post-error response time slowing. Our results suggest that cEMG activity can serve as an index of avoidance motivated control, which is instrumental to adaptive cognitive control when consequences are potentially harmful.

  11. Post-Hartree-Fock studies of the He/Mg(0001) interaction: Anti-corrugation, screening, and pairwise additivity

    NASA Astrophysics Data System (ADS)

    de Lara-Castells, María Pilar; Fernández-Perea, Ricardo; Madzharova, Fani; Voloshina, Elena

    2016-06-01

    The adsorption of noble gases on metallic surfaces represents a paradigmatic case of van-der-Waals (vdW) interaction due to the role of screening effects on the corrugation of the interaction potential [J. L. F. Da Silva et al., Phys. Rev. Lett. 90, 066104 (2003)]. The extremely small adsorption energy of He atoms on the Mg(0001) surface (below 3 meV) and the delocalized nature and mobility of the surface electrons make the He/Mg(0001) system particularly challenging, even for state-of-the-art vdW-corrected density functional-based (vdW-DFT) approaches [M. P. de Lara-Castells et al., J. Chem. Phys. 143, 194701 (2015)]. In this work, we meet this challenge by applying two different procedures. First, the dispersion-corrected second-order Möller-Plesset perturbation theory (MP2C) approach is adopted, using bare metal clusters of increasing size. Second, the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)] is applied at coupled cluster singles and doubles and perturbative triples level, using embedded cluster models of the metal surface. Both approaches provide clear evidences of the anti-corrugation of the interaction potential: the He atom prefers on-top sites, instead of the expected hollow sites. This is interpreted as a signature of the screening of the He atom by the metal for the on-top configuration. The strong screening in the metal is clearly reflected in the relative contribution of successively deeper surface layers to the main dispersion contribution. Aimed to assist future dynamical simulations, a pairwise potential model for the He/surface interaction as a sum of effective He-Mg pair potentials is also presented, as an improvement of the approximation using isolated He-Mg pairs.

  12. Stress-gradient plasticity

    PubMed Central

    Chakravarthy, Srinath S.; Curtin, W. A.

    2011-01-01

    A new model, stress-gradient plasticity, is presented that provides unique mechanistic insight into size-dependent phenomena in plasticity. This dislocation-based model predicts strengthening of materials when a gradient in stress acts over dislocation source–obstacle configurations. The model has a physical length scale, the spacing of dislocation obstacles, and is validated by several levels of discrete-dislocation simulations. When incorporated into a continuum viscoplastic model, predictions for bending and torsion in polycrystalline metals show excellent agreement with experiments in the initial strengthening and subsequent hardening as a function of both sample-size dependence and grain size, when the operative obstacle spacing is proportional to the grain size. PMID:21911403

  13. Respiratory muscle plasticity.

    PubMed

    Rowley, Katharine L; Mantilla, Carlos B; Sieck, Gary C

    2005-07-28

    Plasticity of respiratory muscles must be considered in the context of their unique physiological demands. The continuous rhythmic activation of respiratory muscles makes them among the most active in the body. Respiratory muscles, especially the diaphragm, are non-weight-bearing, and thus, in contrast to limb muscles, are not exposed to gravitational effects. Perturbations in normal activation and load known to induce plasticity in limb muscles may not cause similar adaptations in respiratory muscles. In this review, we explore the structural and functional properties of the diaphragm muscle and their response to alterations in load and activity. Overall, relatively modest changes in diaphragm structural and functional properties occur in response to perturbations in load or activity. However, disruptions in the normal influence of phrenic innervation by frank denervation, tetrodotoxin nerve block and spinal hemisection, induce profound changes in the diaphragm, indicating the substantial trophic influence of phrenic motoneurons on diaphragm muscle.

  14. Compensatory plasticity: time matters

    PubMed Central

    Lazzouni, Latifa; Lepore, Franco

    2014-01-01

    Plasticity in the human and animal brain is the rule, the base for development, and the way to deal effectively with the environment for making the most efficient use of all the senses. When the brain is deprived of one sensory modality, plasticity becomes compensatory: the exception that invalidates the general loss hypothesis giving the opportunity of effective change. Sensory deprivation comes with massive alterations in brain structure and function, behavioral outcomes, and neural interactions. Blind individuals do as good as the sighted and even more, show superior abilities in auditory, tactile and olfactory processing. This behavioral enhancement is accompanied with changes in occipital cortex function, where visual areas at different levels become responsive to non-visual information. The intact senses are in general used more efficiently in the blind but are also used more exclusively. New findings are disentangling these two aspects of compensatory plasticity. What is due to visual deprivation and what is dependent on the extended use of spared modalities? The latter seems to contribute highly to compensatory changes in the congenitally blind. Short-term deprivation through the use of blindfolds shows that cortical excitability of the visual cortex is likely to show rapid modulatory changes after few minutes of light deprivation and therefore changes are possible in adulthood. However, reorganization remains more pronounced in the congenitally blind. Cortico-cortical pathways between visual areas and the areas of preserved sensory modalities are inhibited in the presence of vision, but are unmasked after loss of vision or blindfolding as a mechanism likely to drive cross-modal information to the deafferented visual cortex. The development of specialized higher order visual pathways independently from early sensory experience is likely to preserve their function and switch to the intact modalities. Plasticity in the blind is also accompanied with

  15. Nanotechnology in plastic surgery.

    PubMed

    Ibrahim, Ahmed M S; Gerstle, Theodore L; Rabie, Amr N; Song, Yong-Ak; Melik, Rohat; Han, Jongyoon; Lin, Samuel J

    2012-12-01

    Nanotechnology has made inroads over time within surgery and medicine. Translational medical devices and therapies based on nanotechnology are being developed and put into practice. In plastic surgery, it is anticipated that this new technology may be instrumental in the future. Microelectromechanical systems are one form of nanotechnology that offers the ability to develop miniaturized implants for use in the treatment of numerous clinical conditions. The authors summarize their published preliminary findings regarding a microelectromechanical systems-based electrochemical stimulation method through modulation of ions around the nerve that is potentially implantable and clinically efficacious, and expand upon current and potential usages of nanotechnology in plastic surgery. Sciatic nerves (n = 100) of 50 American bullfrogs were placed on a microfabricated planar gold electrode array and stimulated electrically. Using Ca(2+)-selective membranes, ion concentrations were modulated around the nerve environment in situ. In addition, a comprehensive review of the literature was performed to identify all available data pertaining to the use of nanotechnology in medicine. A 40 percent reduction of the electrical threshold value was observed using the Ca(2+) ion-selective membrane. The uses of nanotechnology specifically applicable to plastic surgery are detailed. Nanotechnology may likely lead to advancements in the art and science of plastic surgery. Using microelectromechanical systems nanotechnology, the authors have demonstrated a novel means of modulating the activation of nerve impulses. These findings have potentially significant implications for the design of special nano-enhanced materials that can be used to promote healing, control infection, restore function, and aid nerve regeneration and rehabilitation.

  16. New perspectives in plastic biodegradation.

    PubMed

    Sivan, Alex

    2011-06-01

    During the past 50 years new plastic materials, in various applications, have gradually replaced the traditional metal, wood, leather materials. Ironically, the most preferred property of plastics--durability--exerts also the major environmental threat. Recycling has practically failed to provide a safe solution for disposal of plastic waste (only 5% out of 1 trillion plastic bags, annually produced in the US alone, are being recycled). Since the most utilized plastic is polyethylene (PE; ca. 140 million tons/year), any reduction in the accumulation of PE waste alone would have a major impact on the overall reduction of the plastic waste in the environment. Since PE is considered to be practically inert, efforts were made to isolate unique microorganisms capable of utilizing synthetic polymers. Recent data showed that biodegradation of plastic waste with selected microbial strains became a viable solution.

  17. Plastic footwear for leprosy.

    PubMed

    Antia, N H

    1990-03-01

    The anaesthetic foot in leprosy poses the most major problem in the rehabilitation of its patients. Various attempts have been made to produce protective footwear such as the microcellular rubber-car-tyre sandals. Unfortunately these attempts have had little success on a large scale because of the inability to produce them in large numbers and the stigma attached to such unusual footwear. While such footwear may be superior to the 'tennis' shoe in protecting the foot from injury by the penetration of sharp objects, it fails to distribute the weight-bearing forces which is the major cause of plantar damage and ulceration in the anaesthetic foot. This can be achieved by providing rigidity to the sole, as demonstrated by the healing of ulcers in plaster of paris casts or the rigid wooden clog. A new type of moulded plastic footwear has been evolved in conjunction with the plastic footwear industry which provides footwear that can be mass produced at a low price and which overcomes the stigma of leprosy. Controlled rigidity is provided by the incorporation of a spring steel shank between the sponge insole and the hard wearing plastic sole. Trials have demonstrated both the acceptability of the footwear and its protective effects as well as its hard wearing properties.

  18. Respiratory muscle plasticity.

    PubMed

    Gransee, Heather M; Mantilla, Carlos B; Sieck, Gary C

    2012-04-01

    Muscle plasticity is defined as the ability of a given muscle to alter its structural and functional properties in accordance with the environmental conditions imposed on it. As such, respiratory muscle is in a constant state of remodeling, and the basis of muscle's plasticity is its ability to change protein expression and resultant protein balance in response to varying environmental conditions. Here, we will describe the changes of respiratory muscle imposed by extrinsic changes in mechanical load, activity, and innervation. Although there is a large body of literature on the structural and functional plasticity of respiratory muscles, we are only beginning to understand the molecular-scale protein changes that contribute to protein balance. We will give an overview of key mechanisms regulating protein synthesis and protein degradation, as well as the complex interactions between them. We suggest future application of a systems biology approach that would develop a mathematical model of protein balance and greatly improve treatments in a variety of clinical settings related to maintaining both muscle mass and optimal contractile function of respiratory muscles.

  19. Adult Visual Cortical Plasticity

    PubMed Central

    Gilbert, Charles D.; Li, Wu

    2012-01-01

    The visual cortex has the capacity for experience dependent change, or cortical plasticity, that is retained throughout life. Plasticity is invoked for encoding information during perceptual learning, by internally representing the regularities of the visual environment, which is useful for facilitating intermediate level vision - contour integration and surface segmentation. The same mechanisms have adaptive value for functional recovery after CNS damage, such as that associated with stroke or neurodegenerative disease. A common feature to plasticity in primary visual cortex (V1) is an association field that links contour elements across the visual field. The circuitry underlying the association field includes a plexus of long range horizontal connections formed by cortical pyramidal cells. These connections undergo rapid and exuberant sprouting and pruning in response to removal of sensory input, which can account for the topographic reorganization following retinal lesions. Similar alterations in cortical circuitry may be involved in perceptual learning, and the changes observed in V1 may be representative of how learned information is encoded throughout the cerebral cortex. PMID:22841310

  20. Microelectronics plastic molded packaging

    SciTech Connect

    Johnson, D.R.; Palmer, D.W.; Peterson, D.W.

    1997-02-01

    The use of commercial off-the-shelf (COTS) microelectronics for nuclear weapon applications will soon be reality rather than hearsay. The use of COTS for new technologies for uniquely military applications is being driven by the so-called Perry Initiative that requires the U.S. Department of Defense (DoD) to accept and utilize commercial standards for procurement of military systems. Based on this philosophy, coupled with several practical considerations, new weapons systems as well as future upgrades will contain plastic encapsulated microelectronics. However, a conservative Department of Energy (DOE) approach requires lifetime predictive models. Thus, the focus of the current project is on accelerated testing to advance current aging models as well as on the development of the methodology to be used during WR qualification of plastic encapsulated microelectronics. An additional focal point involves achieving awareness of commercial capabilities, materials, and processes. One of the major outcomes of the project has been the definition of proper techniques for handling and evaluation of modern surface mount parts which might be used in future systems. This program is also raising the familiarity level of plastic within the weapons complex, allowing subsystem design rules accommodating COTS to evolve. A two year program plan is presented along with test results and commercial interactions during this first year.