WorldWideScience

Sample records for rough annular shear

  1. Experimental study of granular flows in a rough annular shear cell.

    Science.gov (United States)

    Jasti, Venkata; Higgs, C Fred

    2008-10-01

    The study of granular flows in physics has always been important because of their recurring presence in nature and industry. However, the nonlinear and multiphase behavior exhibited by these particulate systems makes them hard to model and predict. Several experiments were conducted in the past to gain insight into granular flows. The current experimental work furthers this insight and specifically attempts to understand the effect of rough surfaces on granular flows, namely, their local flow behavior. Understanding this interaction can have implications on industrial-scale granular problems. In this work, a granular shear cell, a two-dimensional annular shear cell, was developed to conduct shear experiments where roughness is imposed on the driving surface and experimentally quantified. A digital particle tracking velocimetry data retrieval scheme was developed to extract solid fraction, velocity, and granular temperature data from the experiments as a function of the roughness factor and wheel rotation rate. In general, the steady-state results show the two distinct regions as expected-a high-velocity and dilute-gas-like kinetic region near the moving wall and a high-solid-fraction liquid-like frictional flow regime away from the moving wall. Parametric studies conducted show that the normalized slip near the moving wall decreases with increasing wall roughness and decreasing wall rotation rate. Slip is an important parameter which can be easily interpreted as momentum transfer or traction performance in granular systems related to wheel-terrain interaction, agricultural processing, and most notably granular lubrication.

  2. A New Annular Shear Piezoelectric Accelerometer

    DEFF Research Database (Denmark)

    Liu, Bin; Kriegbaum, B.

    2000-01-01

    This paper describes the construction and performance of a recently introduced Annular Shear piezoelectric accelerometer, Type 4511. The design has insulated and double-shielded case. The accelerometer housing is made of stainless steel, AISI 316L. Piezoceramic PZ23 is used. The seismic mass...

  3. Determination of hydraulic resistance of rough annular channels by resistance of rough pipes

    Science.gov (United States)

    Korsun, A. S.; Pisarevsky, M. I.; Fedoseev, V. N.; Kreps, M. V.

    2017-11-01

    According to the current calculation recommendations for turbulent flow, coefficient of hydraulic resistance of a smooth annular channel with an equivalent hydraulic diameter dh is assumed to be equal to the coefficient of hydraulic resistance of a pipe with a diameter dh multiplied by a conversion factor. The value of this conversion factor, depending on the Reynolds number and the ratio of the inner diameter of the annular channel to the outer diameter, varies from 1 to 1.07. That is, a smooth annular channel and a smooth pipe with the same hydraulic diameters have practically the same hydraulic resistance coefficients. In this paper, experiments were conducted to test the feasibility of such an approach to channels with rough walls. According to measurements of water flow and pressure gradient, the coefficients of hydraulic resistance of a rough annular channel and a pipe with hydraulic diameters dh = 6 mm were calculated and compared. A trapezoidal artificial roughness was applied to the surfaces, which are flowing with a liquid. The experiments were carried out on a water circuit in the Reynolds number range from 103 to 105 in the regime of full roughness. The obtained experimental results were compared with calculations of coefficients of hydraulic resistance of pipes with artificial roughness according to the existing recommendations. Conclusions are drawn on the possibility of determining the hydraulic resistance of rough annular channels through the resistance of rough pipes.

  4. Rheological State Diagrams for Rough Colloids in Shear Flow

    Science.gov (United States)

    Hsiao, Lilian C.; Jamali, Safa; Glynos, Emmanouil; Green, Peter F.; Larson, Ronald G.; Solomon, Michael J.

    2017-10-01

    To assess the role of particle roughness in the rheological phenomena of concentrated colloidal suspensions, we develop model colloids with varying surface roughness length scales up to 10% of the particle radius. Increasing surface roughness shifts the onset of both shear thickening and dilatancy towards lower volume fractions and critical stresses. Experimental data are supported by computer simulations of spherical colloids with adjustable friction coefficients, demonstrating that a reduction in the onset stress of thickening and a sign change in the first normal stresses occur when friction competes with lubrication. In the quasi-Newtonian flow regime, roughness increases the effective packing fraction of colloids. As the shear stress increases and suspensions of rough colloids approach jamming, the first normal stresses switch signs and the critical force required to generate contacts is drastically reduced. This is likely a signature of the lubrication films giving way to roughness-induced tangential interactions that bring about load-bearing contacts in the compression axis of flow.

  5. Research on wall shear stress considering wall roughness when shear swirling flow vibration cementing

    Science.gov (United States)

    Cui, Zhihua; Ai, Chi; Feng, Fuping

    2017-01-01

    When shear swirling flow vibration cementing, the casing is revolving periodically and eccentrically, which leads to the annulus fluid in turbulent swirling flow state. The wall shear stress is more than that in laminar flow field when conventional cementing. The paper mainly studied the wall shear stress distribution on the borehole wall when shear swirling flow vibration cementing based on the finite volume method. At the same time, the wall roughness affected and changed the turbulent flow near the borehole wall and the wall shear stress. Based on the wall function method, the paper established boundary conditions considering the wall roughness and derived the formula of the wall shear stress. The results showed that the wall roughness significantly increases the wall shear stress. However, the larger the wall roughness, the greater the thickness of mud cake, which weakening the cementing strength. Considering the effects in a comprehensive way, it is discovered that the particle size of solid phase in drilling fluid is about 0.1 mm to get better cementing quality.

  6. Measurements in the annular shear layer of high subsonic and under-expanded round jets

    Science.gov (United States)

    Feng, Tong; McGuirk, James J.

    2016-01-01

    An experimental study has been undertaken to document compressibility effects in the annular shear layers of axisymmetric jets. Comparison is made of the measured flow development with the well-documented influence of compressibility in planar mixing layers. High Reynolds number (~106) and high Mach number jets issuing from a convergent nozzle at nozzle pressure ratios (NPRs) from 1.28 to 3.0 were measured using laser Doppler anemometry instrumentation. Detailed radial profile data are reported, particularly within the potential core region, for mean velocity, turbulence rms, and turbulence shear stress. For supercritical NPRs the presence of the pressure waves in the inviscid shock cell region as the jet expanded back to ambient pressure was found to exert a noticeable effect on shear layer location, causing this to shift radially outwards at high supercritical NPR conditions. After a boundary layer to free shear layer transition zone, the turbulence development displayed a short region of similarity before adjustment to near-field merged jet behaviour. Peak turbulence rms reduction due to compressibility was similar to that observed in planar layers with radial rms suppression much stronger than axial. Comparison of the compressibility-modified annular shear layer growth rate with planar shear layer data on the basis of the convective Mach number ( M C) showed notable differences; in the annular shear layer, compressibility effects began at lower M C and displayed a stronger reduction in growth. For high Mach number aerospace propulsion applications involving round jets, the current measurements represent a new data set for the calibration/validation of compressibility-affected turbulence models.

  7. Effect of rock joint roughness on its cyclic shear behavior

    Directory of Open Access Journals (Sweden)

    S.M. Mahdi Niktabar

    2017-12-01

    Full Text Available Rock joints are often subjected to dynamic loads induced by earthquake and blasting during mining and rock cutting. Hence, cyclic shear load can be induced along the joints and it is important to evaluate the shear behavior of rock joint under this condition. In the present study, synthetic rock joints were prepared with plaster of Paris (PoP. Regular joints were simulated by keeping regular asperity with asperity angles of 15°–15° and 30°–30°, and irregular rock joints which are closer to natural joints were replicated by keeping the asperity angles of 15°–30° and 15°–45°. The sample size and amplitude of roughness were kept the same for both regular and irregular joints which were 298 mm × 298 mm × 125 mm and 5 mm, respectively. Shear test was performed on these joints using a large-scale direct shear testing machine by keeping the frequency and amplitude of shear load under constant cyclic condition with different normal stress values. As expected, the shear strength of rock joints increased with the increases in the asperity angle and normal load during the first cycle of shearing or static load. With the increase of the number of shear cycles, the shear strength decreased for all the asperity angles but the rate of reduction was more in case of high asperity angles. Test results indicated that shear strength of irregular joints was higher than that of regular joints at different cycles of shearing at low normal stress. Shearing and degradation of joint asperities on regular joints were the same between loading and unloading, but different for irregular joints. Shear strength and joint degradation were more significant on the slope of asperity with higher angles on the irregular joint until two angles of asperities became equal during the cycle of shearing and it started behaving like regular joints for subsequent cycles.

  8. Simulation of synthetic gecko arrays shearing on rough surfaces.

    Science.gov (United States)

    Gillies, Andrew G; Fearing, Ronald S

    2014-06-06

    To better understand the role of surface roughness and tip geometry in the adhesion of gecko synthetic adhesives, a model is developed that attempts to uncover the relationship between surface feature size and the adhesive terminal feature shape. This model is the first to predict the adhesive behaviour of a plurality of hairs acting in shear on simulated rough surfaces using analytically derived contact models. The models showed that the nanoscale geometry of the tip shape alters the macroscale adhesion of the array of fibres by nearly an order of magnitude, and that on sinusoidal surfaces with amplitudes much larger than the nanoscale features, spatula-shaped features can increase adhesive forces by 2.5 times on smooth surfaces and 10 times on rough surfaces. Interestingly, the summation of the fibres acting in concert shows behaviour much more complex that what could be predicted with the pull-off model of a single fibre. Both the Johnson-Kendall-Roberts and Kendall peel models can explain the experimentally observed frictional adhesion effect previously described in the literature. Similar to experimental results recently reported on the macroscale features of the gecko adhesive system, adhesion drops dramatically when surface roughness exceeds the size and spacing of the adhesive fibrillar features.

  9. Dilute suspensions in annular shear flow under gravity: simulation and experiment

    Directory of Open Access Journals (Sweden)

    Schröer Kevin

    2017-01-01

    Full Text Available A dilute suspension in annular shear flow under gravity was simulated using multi-particle collision dynamics (MPC and compared to experimental data. The focus of the analysis is the local particle velocity and density distribution under the influence of the rotational and gravitational forces. The results are further supported by a deterministic approximation of a single-particle trajectory and OpenFOAM CFD estimations of the overcritical frequency range. Good qualitative agreement is observed for single-particle trajectories between the statistical mean of MPC simulations and the deterministic approximation. Wall contact and detachment however occur earlier in the MPC simulation, which can be explained by the inherent thermal noise of the method. The multi-particle system is investigated at the point of highest particle accumulation that is found at 2/3 of the particle revolution, starting from the top of the annular gap. The combination of shear flow and a slowly rotating volumetric force leads to strong local accumulation in this section that increases the particle volume fraction from overall 0.7% to 4.7% at the outer boundary. MPC simulations and experimental observations agree well in terms of particle distribution and a close to linear velocity profile in radial direction.

  10. Magnetic Fluid-Based Squeeze Film Behaviour in Curved Porous-Rotating Rough Annular Plates and Elastic Deformation Effect

    Directory of Open Access Journals (Sweden)

    M. E. Shimpi

    2012-01-01

    Full Text Available Efforts have been directed to study and analyze the squeeze film performance between rotating transversely rough curved porous annular plates in the presence of a magnetic fluid lubricant considering the effect of elastic deformation. A stochastic random variable with nonzero mean, variance, and skewness characterizes the random roughness of the bearing surfaces. With the aid of suitable boundary conditions, the associated stochastically averaged Reynolds' equation is solved to obtain the pressure distribution in turn, which results in the calculation of the load-carrying capacity. The graphical representations establish that the transverse roughness, in general, adversely affects the performance characteristics. However, the magnetization registers a relatively improved performance. It is found that the deformation causes reduced load-carrying capacity which gets further decreased by the porosity. This investigation tends to indicate that the adverse effect of porosity, standard deviation and deformation can be compensated to certain extent by the positive effect of the magnetic fluid lubricant in the case of negatively skewed roughness by choosing the rotational inertia and the aspect ratio, especially for suitable ratio of curvature parameters.

  11. Hydraulic properties of 3D rough-walled fractures during shearing: An experimental study

    Science.gov (United States)

    Yin, Qian; Ma, Guowei; Jing, Hongwen; Wang, Huidong; Su, Haijian; Wang, Yingchao; Liu, Richeng

    2017-12-01

    This study experimentally analyzed the influence of shear processes on nonlinear flow behavior through 3D rough-walled rock fractures. A high-precision apparatus was developed to perform stress-dependent fluid flow tests of fractured rocks. Then, water flow tests on rough-walled fractures with different mechanical displacements were conducted. At each shear level, the hydraulic pressure ranged from 0 to 0.6 MPa, and the normal load varied from 7 to 35 kN. The results show that (i) the relationship between the volumetric flow rate and hydraulic gradient of rough-walled fractures can be well fit using Forchheimer's law. Notably, both the linear and nonlinear coefficients in Forchheimer's law decrease during shearing; (ii) a sixth-order polynomial function is used to evaluate the transmissivity based on the Reynolds number of fractures during shearing. The transmissivity exhibits a decreasing trend as the Reynolds number increases and an increasing trend as the shear displacement increases; (iii) the critical hydraulic gradient, critical Reynolds number and equivalent hydraulic aperture of the rock fractures all increase as the shear displacement increases. When the shear displacement varies from 0 to 15 mm, the critical hydraulic gradient ranges from 0.3 to 2.2 for a normal load of 7 kN and increases to 1.8-8.6 for a normal load of 35 kN; and (iv) the Forchheimer law results are evaluated by plotting the normalized transmissivity of the fractures during shearing against the Reynolds number. An increase in the normal load shifts the fitted curves downward. Additionally, the Forchheimer coefficient β decreases with the shear displacement but increases with the applied normal load.

  12. Dynamic mortar finite element method for modeling of shear rupture on frictional rough surfaces

    Science.gov (United States)

    Tal, Yuval; Hager, Bradford H.

    2017-09-01

    This paper presents a mortar-based finite element formulation for modeling the dynamics of shear rupture on rough interfaces governed by slip-weakening and rate and state (RS) friction laws, focusing on the dynamics of earthquakes. The method utilizes the dual Lagrange multipliers and the primal-dual active set strategy concepts, together with a consistent discretization and linearization of the contact forces and constraints, and the friction laws to obtain a semi-smooth Newton method. The discretization of the RS friction law involves a procedure to condense out the state variables, thus eliminating the addition of another set of unknowns into the system. Several numerical examples of shear rupture on frictional rough interfaces demonstrate the efficiency of the method and examine the effects of the different time discretization schemes on the convergence, energy conservation, and the time evolution of shear traction and slip rate.

  13. Scale Effects in the Flow of a Shear-Thinning Fluid in Rough Fractures

    Science.gov (United States)

    Meheust, Y.; Roques, C.; Le Borgne, T.; Selker, J. S.

    2016-12-01

    The understanding of flow processes involving non-Newtonian fluids in the subsurface is of interest for many engineering applications, from in-situ remediation to enhanced oil recovery. The fluids of interest in such applications (f.e., polymers in remediation) often present shear-thinning properties, i.e., their viscosity decreases as a function of the local shear rate. We investigate how fracture wall roughness impacts the flow of a shear-thinning fluid. Numerical simulations of flow in 3D fracture geometries are carried out by solving a modified Navier-Stokes equation incorporating the Carreau viscous-shear model. The synthetic fractures consist of two rough surfaces which are isotropic self-affine geometries and correlated with each other above a scale which we denote correlation length (see Méheust et al. PAGEOPH 2003). Perfect plastic closing is assumed when the surfaces touch each other. The objective is to test how varying the correlation length impacts the flow behavior, for different degrees of closure, and how this behavior diverges for shear-thinning fluids from what is known for Newtonian fluids. The results from the 3D simulations are also compared to 2D simulations based on the lubrication theory, which we have developed as an extension of the Reynolds equation for Newtonian fluids. We also discuss the implications of our results for the general understanding of the flows of shear-thinning fluids in fractured media and of solute transport by such flows. References:Méheust, Y., & Schmittbuhl, J. (2003). Scale effects related to flow in rough fractures. Pure and Applied Geophysics, 160(5-6), 1023-1050.

  14. On Shear Stress Distributions for Flow in Smooth or Partially Rough Annuli

    Energy Technology Data Exchange (ETDEWEB)

    Kjellstroem, B.; Hedberg, S.

    1966-08-15

    It is commonly assumed that for turbulent flow in annuli the radii of zero shear and maximum velocity are coincident. By inspection of the differential equations for such flow and by an integral analysis it is shown that this is not necessarily true. To check whether important differences could occur, experiments were made in which velocity and shear stress distributions were measured in one smooth and two partially rough annuli. The results show no difference in the radii for the smooth annulus, but for the partially rough annuli there was a small but significant difference. This difference explains the breakdown of Hall's transformation theory reported by other investigators. The error introduced by use of Hall's theory is however small, of the order of 10 % or less.

  15. Gecko toe and lamellar shear adhesion on macroscopic, engineered rough surfaces.

    Science.gov (United States)

    Gillies, Andrew G; Henry, Amy; Lin, Hauwen; Ren, Angela; Shiuan, Kevin; Fearing, Ronald S; Full, Robert J

    2014-01-15

    The role in adhesion of the toes and lamellae - intermediate-sized structures - found on the gecko foot remains unclear. Insight into the function of these structures can lead to a more general understanding of the hierarchical nature of the gecko adhesive system, but in particular how environmental topology may relate to gecko foot morphology. We sought to discern the mechanics of the toes and lamellae by examining gecko adhesion on controlled, macroscopically rough surfaces. We used live Tokay geckos, Gekko gecko, to observe the maximum shear force a gecko foot can attain on an engineered substrate constructed with sinusoidal patterns of varying amplitudes and wavelengths in sizes similar to the dimensions of the toes and lamellae structures (0.5 to 6 mm). We found shear adhesion was significantly decreased on surfaces that had amplitudes and wavelengths approaching the lamella length and inter-lamella spacing, losing 95% of shear adhesion over the range tested. We discovered that the toes are capable of adhering to surfaces with amplitudes much larger than their dimensions even without engaging claws, maintaining 60% of shear adhesion on surfaces with amplitudes of 3 mm. Gecko adhesion can be predicted by the ratio of the lamella dimensions to surface feature dimensions. In addition to setae, remarkable macroscopic-scale features of gecko toes and lamellae that include compliance and passive conformation are necessary to maintain contact, and consequently, generate shear adhesion on macroscopically rough surfaces. Findings on the larger scale structures in the hierarchy of gecko foot function could provide the biological inspiration to drive the design of more effective and versatile synthetic fibrillar adhesives.

  16. Boundary-dependent mechanical properties of graphene annular under in-plane circular shearing via atomistic simulations.

    Science.gov (United States)

    Li, Yinfeng; Lin, Qianling; Cui, Daxiang

    2017-02-13

    Graphene annulus possesses special wrinkling phenomenon with wide range of potential applications. Using molecular dynamics simulation, this study concerns the effect of boundary on the mechanical properties of circular and elliptical graphene annuli under circular shearing at inner edge. Both the wrinkle characteristic and torque capacity of annular graphene can be effectively tuned by outer boundary radius and aspect ratio. For circular annulus with fixed inner radius, the critical angle of rotation can be increased by several times without sacrificing its torque capacity by increasing outer boundary radius. The wrinkle characteristic of graphene annulus with elliptical outer boundary differs markedly with that of circular annulus. Torque capacity anomalously decreases with the increase of aspect ratio, and a coupled effect of the boundary aspect ratio and the ratio of minor axis to inner radius on wrinkling are revealed. By studying the stress distribution and wrinkle characteristics, we find the decay of torque capacity is the result of circular stress concentration around the minor axis, while the nonuniform stress distribution is anomalously caused by the change of wrinkle profiles near the major axis. The specific mechanism of out-of-plane deformation on in-plane strength provides a straightforward means to develop novel graphene-based devices.

  17. Effect of sandblasting on surface roughness of zirconia-based ceramics and shear bond strength of veneering porcelain.

    Science.gov (United States)

    He, Min; Zhang, Zutai; Zheng, Dongxiang; Ding, Ning; Liu, Yan

    2014-01-01

    This study aims to investigate the effect of sandblasting on the surface roughness of zirconia and the shear bond strength of the veneering porcelain. Pre-sintered zirconia plates were prepared and divided into four groups. Group A were not treated at all; group B were first sandblasted under 0.2 MPa pressure and then densely sintered; group C and D were sintered first, and then sandblasted under 0.2 MPa and 0.4 MPa pressures respectively. Surface roughness was measured and 3D roughness was reconstructed for the specimens, which were also analyzed with X-ray diffractometry. Finally after veneering porcelain sintering, shear bond tests were conducted. Sandblasting zirconia before sintering significantly increased surface roughness and the shear bond strength between zirconia and veneering porcelain (pveneering porcelain.

  18. Powder flow in an automated uniaxial tester and an annular shear cell: a study of pharmaceutical excipients and analytical data comparison.

    Science.gov (United States)

    Kuentz, Martin; Schirg, Peter

    2013-09-01

    An automated version of uniaxial powder flow testing has recently been developed and there is a need for experimental data from pharmaceutical powders. To compare the novel testing method with an annular shear cell using different pharmaceutical excipients. A particular aim was to gain an improved understanding of potential differences in the obtained flow results. Nine excipients were studied with both flow testers at different consolidation levels. Unconfined yield strengths were determined at similar major consolidation stresses. Finally, an anisotropic stress factor was calculated and the fractal character of the powders was assessed by means of image analysis in a rotating drum. Data correlated generally well; however, the unconfined yield strength from uniaxial testing resulted mostly in lower values compared to annular shear cell testing. Differences were specific for the given excipients and mannitol demonstrated the highest discrepancy of measured flow parameters. The differences were first discussed by considering wall friction, anisotropy of forces, brittleness as well as the fractal nature of the powder surface. This heterogeneity of the powder as well as the anisotropy of forces was also found to be important for the relative flow index. The automated uniaxial method demonstrated faster and more reproducible flow testing as compared to an annular shear cell. Therefore, the new method has a high potential in pharmaceutics for example in the quality-control of powders.

  19. Experimental signature of the pair trajectories of rough spheres in the shear-induced microstructure in noncolloidal suspensions.

    Science.gov (United States)

    Blanc, Frédéric; Peters, François; Lemaire, Elisabeth

    2011-11-11

    The shear-induced microstructure in a semidilute noncolloidal suspension is studied. A high-resolution pair distribution function in the plane of shear is experimentally determined. It is shown to be anisotropic, with a depleted direction close to the velocity axis in the recession quadrant. The influence of roughness on the interaction between particles is quantitatively evidenced. The experimental results compare well with a model from particle pair trajectories.

  20. Late-Time Mixing Sensitivity to Initial Broadband Surface Roughness in High-Energy-Density Shear Layers

    Energy Technology Data Exchange (ETDEWEB)

    Flippo, K. A.; Doss, F. W.; Kline, J. L.; Merritt, E. C.; Capelli, D.; Cardenas, T.; DeVolder, B.; Fierro, F.; Huntington, C. M.; Kot, L.; Loomis, E. N.; MacLaren, S. A.; Murphy, T. J.; Nagel, S. R.; Perry, T. S.; Randolph, R. B.; Rivera, G.; Schmidt, D. W.

    2016-11-23

    Using a large volume high-energy-density fluid shear experiment (8.5 cm3) at the National Ignition Facility, we have demonstrated for the first time the ability to significantly alter the evolution of a supersonic sheared mixing layer by controlling the initial conditions of that layer. By altering the initial surface roughness of the tracer foil, we demonstrate the ability to transition the shear mixing layer from a highly ordered system of coherent structures to a randomly ordered system with a faster growing mix layer, indicative of strong mixing in the layer at a temperature of several tens of electron volts and at near solid density. Simulations using a turbulent-mix model show good agreement with the experimental results and poor agreement without turbulent mix.

  1. A new peak shear strength criterion for rock joints which includes spectral parameters as roughness measures

    Energy Technology Data Exchange (ETDEWEB)

    Kulatilake, P.H.S.W.; Shou, G. [Univ. of Arizona, Tucson, AZ (United States); Huang, T.H. [National Taiwan Univ., Taipei (Taiwan, Province of China)

    1996-04-01

    Most of the natural rock joint surface profiles do not belong to the self similar fractal category. In general, roughness profiles of rock joints consist of non-stationary and stationary components. At the simplest level, only one parameter is sufficient to quantify non-stationary joint roughness. The average inclination angle I, along with the direction considered for the joint surface, is suggested to capture the non-stationary roughness. It is shown that even though the fractal dimension D is a useful parameter, it alone is insufficient to quantify the stationary roughness of non-self similar profiles.

  2. Effect of oxidation and surface roughness on the shear strength of single-lap-joint adhesively bonded metal specimens by tension loading

    National Research Council Canada - National Science Library

    Khan, M H; Gali, O A; Edrisy, A; Riahi, A R

    2016-01-01

    An experimental investigation was performed to study the effect of surface roughness and oxidation on the shear strength of single-lap-joints of AA6061, AA7075 aluminum alloys and an AISI 1080 steel...

  3. Annular pancreas

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/001142.htm Annular pancreas To use the sharing features on this page, please enable JavaScript. An annular pancreas is a ring of pancreatic tissue that encircles ...

  4. Surface tension effects on vertical upward annular flows in a small diameter pipe

    Energy Technology Data Exchange (ETDEWEB)

    Sadatomi, Michio, E-mail: sadatomi@mech.kumamoto-u.ac.jp [Dept. of Advanced Mechanical Systems, Kumamoto Univ., 39-1, Kurokami 2-chome, Chuou-ku, Kumamoto 860-8555 (Japan); Kawahara, Akimaro [Dept. of Advanced Mechanical Systems, Kumamoto Univ., 39-1, Kurokami 2-chome, Chuou-ku, Kumamoto 860-8555 (Japan); Suzuki, Aruta [Plant Design & Engineering Dept., Environment, Energy & Plant Headquarters, Hitachi Zosen Corporation, 7-89, Nankokita 1-chome, Suminoe-ku, Osaka, 559-8559 (Japan)

    2016-12-15

    Highlights: • Surface tension effects were clarified on annular flow in a small diameter pipe. • The mean liquid film thickness became thinner with decreasing of surface tension. • The liquid droplet fraction and the interfacial shear stress became higher with it. • New prediction methods for the above parameters were developed and validated. - Abstract: Experiments were conducted to study the surface tension effects on vertical upward annular flows in a 5 mm I.D. pipe using water and low surface tension water with a little surfactant as the test liquid and air as the test gas. Firstly, the experimental results on the mean liquid film thickness, the liquid droplet fraction and the interfacial shear stress in annular flows together with some flow pictures are presented to clarify the surface tension effects. From these, the followings are clarified: In the low surface tension case, the liquid film surface becomes rough, the liquid film thickness thin, the liquid droplet fraction high, and the interfacial shear stress high. Secondary, correlations in literatures for the respective parameters are tested against the present data. The test results show that no correlation for the respective parameters could predict well the present data. Thus, correlations are revised by accounting for the surface tension effects. The results of the experiments, the correlations tests and their revisions mentioned above are presented in the present paper.

  5. Subcutaneous granuloma annulare

    Directory of Open Access Journals (Sweden)

    Dhar Sandipan

    1994-01-01

    Full Text Available Two cases of subcutaneos granuloma annulare are reported. Clinical presentation was in the form of hard subcutaneous nodules; histopathology confirmed the clinical diagnosis. The cases were unique because of onset in adult hood, occurrence over unusual sites and absence of classical lesions of granuloma annulare elsewhere.

  6. Subcutaneous granuloma annulare

    Directory of Open Access Journals (Sweden)

    Dhar Sandipan

    1993-01-01

    Full Text Available Two cases of subcutaneous granuloma annulare are reported. Clinical presentation was in the form of hard subcutaneous nodules, histopathology confirmed the clinical diagnosis. The cases were unique because of onset in adult age, occurrence over unusual sites and absence of classical lesions of granuloma annulare elsewhere.

  7. Annular pancreas (image)

    Science.gov (United States)

    Annular pancreas is an abnormal ring or collar of pancreatic tissue that encircles the duodenum (the part of the ... intestine that connects to stomach). This portion of pancreas can constrict the duodenum and block or impair ...

  8. Predicting the plan annular pressure using the power law flow model in horizontal directional drilling

    National Research Council Canada - National Science Library

    Bayat, Alireza; Yi, Yaolin; Rostami, Ali; Osbak, Manley

    2016-01-01

    .... The annular pressures were predicted using the power law model with rheological parameters determined from a six-speed viscometer with varying shear rate ranges from 3 to 600 RPM for two HDD projects...

  9. Annular Planar Monopole Antennas

    OpenAIRE

    Chen, Z. N.; Ammann, Max; Chia, W.Y. W.; See, T. S.P.

    2002-01-01

    A type of annular planar monopole antenna is presented. The impedance and radiation characteristics of the monopole with different holes and feed gaps are experimentally examined. The measured results demonstrate that the proposed antenna is capable of providing significantly broad impedance bandwidth with acceptable radiation performance.

  10. Generalized granuloma annulare

    Directory of Open Access Journals (Sweden)

    Khatri M

    1995-01-01

    Full Text Available A 35-years-old female patient had generalized pruritic papular lesions, distributed like dermatitis herpetiformis for last 4 years. Histopathologic changes were typical of granuloma annulare with negative results of direct immunofluorescence. The patient did not have association of diabetes mellitus or any other systemic disease. She failed to respond to dapsone therapy and 13-cis-retinoic acid.

  11. Rubber friction and force transmission during the shearing process of actively-driven vacuum grippers on rough surfaces; Elastomerreibung und Kraftuebertragung beim Abscheren von aktiv betriebenen Vakuumgreifern auf rauen Oberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Kern, Patrick

    2016-12-21

    Nowadays, vacuum grippers come in many different shapes and sizes. Their stability is guaranteed through specially manufactured metal fittings. These fittings are non-positively and positively connected to the elastic part of the vacuum gripper. The design of the elastic part may vary, though. Elastomer components are used to ensure tightness for the negative pressure in the active cave chamber of the vacuum gripper, as well as for the transfer of shearing forces, which acting parallel to the surface. Some vacuum grippers feature one elastomer for both the sealing function and the transfer of shear forces; other gripper types are equipped with various elastomers for those applications. The vacuum grippers described in this work are equipped with structured rubber friction pads, their tightness being ensured by sealing lips made of a flexible foam rubber. A restraint system consisting of one or several vacuum grippers must be sized prior to its actual practical use. For the transmission of shearing forces, which acting parallel to the surface, it is necessary to take the tribological system, consisting of the suction element's elastomer and the base material, into account since these loads put shearing stress on the vacuum gripper. In practice, however, a standardized value is given for the coefficient of friction μ; i.e. the ratio of transmissible frictional force to the normal force. This does neither include a detailed description of the elastomer used nor of the roughness of the base material. The standardized friction coefficients cannot be applied to the practical design of restraint systems. The present work includes the analysis of the load transmission and the modeling of the friction coefficients μ on rough surfaces during the shearing process of actively-driven vacuum grippers. Based on current theories, the phenomenon of elastomeric friction can be attributed to the two main components of hysteresis and adhesion friction. Both components are

  12. Trapping and displacement of liquid collars and plugs in rough-walled tubes

    Science.gov (United States)

    Xu, Feng; Jensen, Oliver E.

    2017-09-01

    A liquid film wetting the interior of a long circular cylinder redistributes under the action of surface tension to form annular collars or occlusive plugs. These equilibrium structures are invariant under axial translation within a perfectly smooth uniform tube and therefore can be displaced axially by very weak external forcing. We consider how this degeneracy is disrupted when the tube wall is rough, and determine threshold conditions under which collars or plugs resist displacement under forcing. Wall roughness is modeled as a nonaxisymmetric Gaussian random field of prescribed correlation length and small variance, mimicking some of the geometric irregularities inherent in applications such as lung airways. The thin film coating this surface is modeled using lubrication theory. When the roughness is weak, we show how the locations of equilibrium collars and plugs can be identified in terms of the azimuthally averaged tube radius; we derive conditions specifying equilibrium collar locations under an externally imposed shear flow, and plug locations under an imposed pressure gradient. We use these results to determine the probability of external forcing being sufficient to displace a collar or plug from a rough-walled tube, when the tube roughness is defined only in statistical terms.

  13. Granuloma annulare - close-up (image)

    Science.gov (United States)

    Granuloma annulare is usually a self-limiting disorder characterized by raised lesions arranged in an annular shape. ... This picture shows a close-up of a granuloma annulare that is subcutaneous (deeper). It demonstrates the ...

  14. Portal Annular Pancreas

    Science.gov (United States)

    Harnoss, Jonathan M.; Harnoss, Julian C.; Diener, Markus K.; Contin, Pietro; Ulrich, Alexis B.; Büchler, Markus W.; Schmitz-Winnenthal, Friedrich H.

    2014-01-01

    Abstract Portal annular pancreas (PAP) is an asymptomatic congenital pancreas anomaly, in which portal and/or mesenteric veins are encased by pancreas tissue. The aim of the study was to determine the role of PAP in pancreatic surgery as well as its management and potential complication, specifically, postoperative pancreatic fistula (POPF). On the basis of a case report, the MEDLINE and ISI Web of Science databases were systematically reviewed up to September 2012. All articles describing a case of PAP were considered. In summary, 21 studies with 59 cases were included. The overall prevalence of PAP was 2.4% and the patients' mean (SD) age was 55.9 (16.2) years. The POPF rate in patients with PAP (12 pancreaticoduodenectomies and 3 distal pancreatectomies) was 46.7% (in accordance with the definition of the International Study Group of Pancreatic Surgery). Portal annular pancreas is a quite unattended pancreatic variant with high prevalence and therefore still remains a clinical challenge to avoid postoperative complications. To decrease the risk for POPF, attentive preoperative diagnostics should also focus on PAP. In pancreaticoduodenectomy, a shift of the resection plane to the pancreas tail should be considered; in extensive pancreatectomy, coverage of the pancreatic remnant by the falciform ligament could be a treatment option. PMID:25207658

  15. Nerve involvement in granuloma annulare.

    Science.gov (United States)

    Longmire, Michelle; DiCaudo, David J; Dahl, Mark V

    2012-01-01

    Nerve involvement developed in a patient with granuloma annulare, as evidenced by a perineural infiltrate of histiocytes in the dermis. The histopathologic pattern was suggestive of leprosy. No mycobacteria were observed, and neurologic testing was normal. To determine whether inflammation of the nerves or perineural tissue is common in granuloma annulare, we studied the cutaneous nerves in skin biopsy specimens from 14 patients with granuloma annulare. Sections were stained with hematoxylin-eosin to highlight inflammatory cells and with S-100 to identify cutaneous nerves. No inflammation around nerves was found in 12 specimens, abutting granulomatous inflammation was found in 1 specimen, and enveloping granulomatous inflammation was found in 1 specimen. No nerves were infiltrated by inflammatory cells. Perineural granulomatous inflammation resembling the perineural infiltrate of leprosy appears to be an uncommon characteristic of granuloma annulare. Clinical correlation and acid-fast stains can assist in establishing the correct diagnosis.

  16. Annular Hybrid Rocket Motor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Engineers at SpaceDev have conducted a preliminary design and analysis of a proprietary annular design concept for a hybrid motor. A U.S. Patent application has been...

  17. Shear layer flame stabilization sensitivities in a swirling flow

    National Research Council Canada - National Science Library

    Foley, Christopher; Chterev, Ianko; Noble, Bobby; Seitzman, Jerry; Lieuwen, Tim

    A variety of different flame configurations and heat release distributions exist in high swirl, annular flows, due to the existence of inner and outer shear layers as well a vortex breakdown bubble...

  18. Adiabatic Steam-Water Annular Flow in an Annular Geometry

    DEFF Research Database (Denmark)

    Andersen, P. S.; Würtz, J.

    1981-01-01

    Experimental results for fully developed steam-water annular flow in annular geometries are presented. Rod and tube film flow rates and axial pressure gradients were measured for mass fluxes between 500 and 2000 kg/m2s, steam qualities between 20 and 60 per cent and pressures ranging from 3 to 9...... MPa. It was found that the measured tube film flow rate per unit tube perimeter is always many times greater than the corresponding rod film flow rate. Possible explanations for this asymmetry are discussed....

  19. Physical model for turbulent friction on rough surfaces

    CERN Document Server

    Li, Zhuoqun

    2016-01-01

    We present an analytical expression for turbulent friction on rough surfaces with regularly distributed roughness elements. Wall shear stresses are expressed as functions of physical quantities. Surfaces with varying roughness densities and roughness elements with different aspect ratios are considered. As the drag on each roughness element decreases as roughness density increases, we propose a straight forward method based on momentum conservation to deduce drag on elements by expressing it as a function of the maximum drag on elements and drag reductions ratios. We proposed a drag reduction effect of momentum redistribution and studied the mutual sheltering effect. Reduction ratios for redistribution effect and mutual sheltering effect are deduced, for different rough surfaces. These two drag reduction mechanisms are significant for sparse and dense surfaces, respectively. The shear stress on elements and the total shear stress are obtained as the result of the drag analysis. The estimated wall shear stress...

  20. Benign concentric annular macular dystrophy

    Directory of Open Access Journals (Sweden)

    Luísa Salles de Moura Mendonça

    2015-06-01

    Full Text Available The purpose of the authors is to show clinical findings of a patient with benign concentric annular macular dystrophy, which is an unusual condition, and part of the "bull’s eye" maculopathy differential diagnosis. An ophthalmologic examination with color perception, fluorescein angiography, and ocular electrophysiology was performed.

  1. Subcutaneous granuloma annulare: radiologic appearance

    Energy Technology Data Exchange (ETDEWEB)

    Kransdorf, M.J. [Saint Mary`s Hospital, Richmond, VA (United States). Dept. of Radiol.]|[Department of Radiologic Pathology, Armed Forces Institute of Pathology, Washington, DC (United States); Murphey, M.D. [Department of Radiologic Pathology, Armed Forces Institute of Pathology, Washington, DC (United States)]|[Department of Radiology and Nuclear Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland (United States)]|[Department of Radiology, School of Medicine, University of Maryland, Baltimore, Maryland (United States); Temple, H.T. [Department of Orthopedic Surgery, University of Virginia Health Sciences Center, Charlottesville, Virginia (United States)]|[Department of Orthopedic Pathology, Armed Forces Institute of Pathology, Washington, DC (United States)

    1998-05-01

    Objective. Granuloma annulare is an uncommon benign inflammatory dermatosis characterized by the formation of dermal papules with a tendency to form rings. There are several clinically distinct forms. The subcutaneous form is the most frequently encountered by radiologists, with the lesion presenting as a superficial mass. There are only a few scattered reports of the imaging appearance of this entity in the literature. We report the radiologic appearance of five cases of subcutaneous granuloma annulare. Design and patients. The radiologic images of five patients (three male, two female) with subcutaneous granuloma annulare were retrospectively studied. Mean patient age was 6.4 years (range, 2-13 years). The lesions occurred in the lower leg (two), foot, forearm, and hand. MR images were available for all lesions, gadolinium-enhanced imaging in three cases, radiographs in four, and bone scintigraphy in one. Results. Radiographs showed unmineralized nodular masses localized to the subcutaneous adipose tissue. The size range, in greatest dimension on imaging studies, was 1-4 cm. MR images show a mass with relatively decreased signal intensity on all pulse sequences, with variable but generally relatively well defined margins. There was extensive diffuse enhancement following gadolinium administration. Conclusion. The radiologic appearance of subcutaneous granuloma annulare is characteristic, typically demonstrating a nodular soft-tissue mass involving the subcutaneous adipose tissue. MR images show a mass with relatively decreased signal intensity on all pulse sequences and variable but generally well defined margins. There is extensive diffuse enhancement following gadolinium administration. Radiographs show a soft-tissue mass or soft-tissue swelling without evidence of bone involvement or mineralization. This radiologic appearance in a young individual is highly suggestive of subcutaneous granuloma annulare. (orig.) With 3 figs., 17 refs.

  2. Widespread Granuloma Annulare in Photo Distribution

    Directory of Open Access Journals (Sweden)

    Ayşegül Polat

    2017-12-01

    Full Text Available Granuloma annulare is relatively common idiopathic disease of dermis and subcutaneous tissue. It can be observed of all races and ages, but it effects woman more often (2:1. Widespread granuloma annulare, diffuse but symmetrically located occurs as papular or annular pustules composed of more than ten and often hundreds of lesions. Because of the rare occurrence of common granuloma annulare cases with photosensitivity distribution, we present a case of a 49 year-old woman who had generalized granuloma annulare on the neck, dorsal aspects of the hands and extensor surfaces of the arms showing photosensitive distribution and that responded well to topical and intralesional steroid treatment.

  3. Rock discontinuity surface roughness variation with scale

    Science.gov (United States)

    Bitenc, Maja; Kieffer, D. Scott; Khoshelham, Kourosh

    2017-04-01

    ABSTRACT: Rock discontinuity surface roughness refers to local departures of the discontinuity surface from planarity and is an important factor influencing the shear resistance. In practice, the Joint Roughness Coefficient (JRC) roughness parameter is commonly relied upon and input to a shear strength criterion such as developed by Barton and Choubey [1977]. The estimation of roughness by JRC is hindered firstly by the subjective nature of visually comparing the joint profile to the ten standard profiles. Secondly, when correlating the standard JRC values and other objective measures of roughness, the roughness idealization is limited to a 2D profile of 10 cm length. With the advance of measuring technologies that provide accurate and high resolution 3D data of surface topography on different scales, new 3D roughness parameters have been developed. A desirable parameter is one that describes rock surface geometry as well as the direction and scale dependency of roughness. In this research a 3D roughness parameter developed by Grasselli [2001] and adapted by Tatone and Grasselli [2009] is adopted. It characterizes surface topography as the cumulative distribution of local apparent inclination of asperities with respect to the shear strength (analysis) direction. Thus, the 3D roughness parameter describes the roughness amplitude and anisotropy (direction dependency), but does not capture the scale properties. In different studies the roughness scale-dependency has been attributed to data resolution or size of the surface joint (see a summary of researches in [Tatone and Grasselli, 2012]). Clearly, the lower resolution results in lower roughness. On the other hand, have the investigations of surface size effect produced conflicting results. While some studies have shown a decrease in roughness with increasing discontinuity size (negative scale effect), others have shown the existence of positive scale effects, or both positive and negative scale effects. We

  4. Review of oil water core annular flow

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, S.; Mandal, T.K.; Das, G. [Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302 (India); Das, P.K. [Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302 (India)

    2009-10-15

    The emerging energy efficient technology in the field of high viscous oil transportation is water-lubricated transport of heavy oil, known as core annular flow or CAF. This paper provides a brief review of the past studies on oil-water core annular flows - including studies on hydrodynamics as well as stability of flow. (author)

  5. Soliton bunching in annular Josephson junctions

    DEFF Research Database (Denmark)

    Vernik, I.V; Lazarides, Nickos; Sørensen, Mads Peter

    1996-01-01

    By studying soliton (fluxon) motion in long annular Josephson junctions it is possible to avoid the influence of the boundaries and soliton-soliton collisions present in linear junctions. A new experimental design consisting of a niobium coil placed on top of an annular junction has been used to ...

  6. Inner Annular Gap and Related Topics

    Science.gov (United States)

    Lee, K. J.; Qiao, G. J.; Wang, H. G.; Zhang, B.; Xu, R. X.

    2006-12-01

    Geometrical properties of the annular gap model, efforts of observational tests on it and applications of the model to explain the bi-drifting phenomenon are introduced in this paper. It was shown that in the frame of the annular gap model the observed γ-ray and radio radiation properties of pulsars can be well reproduced. The annular gap model can naturally explain the bi-drifting phenomenon, which is difficult to be understood in classical inner vacuum models. Recently, Wang et al. proposed an independent geometrical method to determine the location for the multi-band radiation regions of PSR B1055-52. They found that the γ-ray emission and radio main pulse emission come from the annular gap, while the radio inter-pulse originates from the core cap region. The results show that the constrained radio and γ-ray emission regions are generally consistent with the predictions of the annular gap model.

  7. Effect of annular secondary conductor in a linear electromagnetic ...

    Indian Academy of Sciences (India)

    axial force density using aluminum annular ring as secondary mold. Hollow annular ring, annular ring with a solid cylinder and solid cylinder having the same outer diameter as that of annular ring are considered for numerical and experimental validation. Figure 1 shows a basic model of a linear electromagnetic stirrer with ...

  8. Characterization of interfacial waves in horizontal core-annular flow

    Science.gov (United States)

    Tripathi, Sumit; Bhattacharya, Amitabh; Singh, Ramesh; Tabor, Rico F.

    2016-11-01

    In this work, we characterize interfacial waves in horizontal core annular flow (CAF) of fuel-oil and water. Experimental studies on CAF were performed in an acrylic pipe of 15.5mm internal diameter, and the time evolution of the oil-water interface shape was recorded with a high speed camera for a range of different flow-rates of oil (Qo) and water (Qw). The power spectrum of the interface shape shows a range of notable features. First, there is negligible energy in wavenumbers larger than 2 π / a , where a is the thickness of the annulus. Second, for high Qo /Qw , there is no single dominant wavelength, as the flow in the confined annulus does not allow formation of a preferred mode. Third, for lower Qo /Qw , a dominant mode arises at a wavenumber of 2 π / a . We also observe that the power spectrum of the interface shape depends weakly on Qw, and strongly on Qo, perhaps because the net shear rate in the annulus appears to depend weakly on Qw as well. We also attempt to build a general empirical model for CAF by relating the interfacial stress (calculated via the mean pressure gradient) to the flow rate in the annulus, the annular thickness and the core velocity. Authors are thankful to Orica Mining Services (Australia) for the financial support.

  9. A clinical study of annular cyclitis

    Directory of Open Access Journals (Sweden)

    Marilita Michael Moschos

    2009-02-01

    Full Text Available Marilita Michael Moschos1, Yan Guex-Crosier2, Ioannis Margetis1, Leonidas Zografos21Department of Ophthalmology, University of Athens, Greece; 2Jules Gonin Eye Hospital, University of Lausanne, SwitzerlandPurpose: To investigate six cases of annular cyclitis.Methods: All patients with impairment of visual acuity underwent complete ophthalmologic examination, color fundus photography, laboratory tests and fluorescein angiography. Indocyanine green (ICG angiography and B-scan ultrasonography were also performed in three cases in order to diagnose the disease.Results: All patients presented a unilateral or bilateral granulomatous uveitis, associated with inflammatory annular cyclitis. They had a shallow anterior chamber, a mildly elevated intraocular pressure (under 25 mm Hg and an annular serous retinal detachment. A resolution was observed after specific therapy associated with systemic prednisolone therapy and antiglaucomatous drops.Conclusion: This is the first description of an observational study of six patients with inflammatory annular cyclitis.Keywords: cyclitis, uveitis, malignant glaucoma

  10. Divergent Field Annular Ion Engine Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed work investigates an approach that would allow an annular ion engine geometry to achieve ion beam currents approaching the Child-Langmuir limit. In this...

  11. Liquid Annular Seal CFD Analysis for Rotordynamic Force Prediction

    Science.gov (United States)

    Moore, Jeff; Palazzolo, Alan

    2006-01-01

    A commercially available code is utilized to analyze a plain and grooved liquid annular seal. These type seals are commonly used in modern turbopumps and have a pronounced effect on the rotordynamic behavior of these systems. Accurate prediction of both leakage and dynamic reaction forces is vital to ensure good performance and sound mechanical operation. The code SCISEAL developed by CFDRC is a generic 3-D, finite volume based CFD code solving the 3-D Reynolds averaged Navier Stokes equations. The code allows body-fitted, multi-blocked structured grids, turbulence modeling, rotating coordinate frames, as well as integration of dynamic pressure and shear forces on the rotating journal. The code may be used with the commercially available pre-and post-processing codes from CFDRC as well.

  12. The Incipient Motion Features of Sediment from Yangtze Estuary: Annular Flume Experiments.

    Science.gov (United States)

    Wei, Huang; Ya-Kun, Liu; Hua-Lin, Wu; Yuan-Yang, Wan

    2017-10-16

    In this study, annular flume experiments are carried out, using the sediment samples collected from Yangtze estuary. The incipient velocity and the incipient shear stress of three different groups of median grain size of sediment are given. The turbulent kinetic energy method (TKE) is used to determine the bed shear stress (τ), by evaluating variations in the suspended sediment concentration (SSC) within the water column. The suspended sediment concentration increases with the increase of the bed shear stress. When the sediment concentration reaches a certain concentration, the rate of change in τ obviously slows down. As the concentration increasing again, the bed shear stress grows rapidly with different growth rate attributed to different grain size. The results of the experiments indicate that SSC and grain size have strong influence on τ.

  13. Adaptive optics scanning ophthalmoscopy with annular pupils

    Science.gov (United States)

    Sulai, Yusufu N.; Dubra, Alfredo

    2012-01-01

    Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections. PMID:22808435

  14. Granuloma annulare presenting as contact dermatitis.

    Science.gov (United States)

    Marty, Chelsy L; Cheng, Janet F

    2005-03-01

    Granuloma annulare is a benign idiopathic disorder of the dermis that has various clinical presentations and an unknown etiology. We discuss a patient who presented with a contact dermatitis that demonstrated granuloma annulare on biopsy. The most likely etiologic agent was a substance known as FAZ (an exhaust product of Kodak DryView laser imaging film), to which the patient was exposed in his occupation.

  15. Adaptive optics scanning ophthalmoscopy with annular pupils.

    Science.gov (United States)

    Sulai, Yusufu N; Dubra, Alfredo

    2012-07-01

    Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections.

  16. Laser Doppler velocimeter measurements and laser sheet imaging in an annular combustor model. M.S. Thesis, Final Report

    Science.gov (United States)

    Dwenger, Richard Dale

    1995-01-01

    An experimental study was conducted in annular combustor model to provide a better understanding of the flowfield. Combustor model configurations consisting of primary jets only, annular jets only, and a combination of annular and primary jets were investigated. The purpose of this research was to provide a better understanding of combustor flows and to provide a data base for comparison with computational models. The first part of this research used a laser Doppler velocimeter to measure mean velocity and statistically calculate root-mean-square velocity in two coordinate directions. From this data, one Reynolds shear stress component and a two-dimensional turbulent kinetic energy term was determined. Major features of the flowfield included recirculating flow, primary and annular jet interaction, and high turbulence. The most pronounced result from this data was the effect the primary jets had on the flowfield. The primary jets were seen to reduce flow asymmetries, create larger recirculation zones, and higher turbulence levels. The second part of this research used a technique called marker nephelometry to provide mean concentration values in the combustor. Results showed the flow to be very turbulent and unsteady. All configurations investigated were highly sensitive to alignment of the primary and annular jets in the model and inlet conditions. Any imbalance between primary jets or misalignment of the annular jets caused severe flow asymmetries.

  17. Characterization of interfacial waves and pressure drop in horizontal oil-water core-annular flows

    Science.gov (United States)

    Tripathi, Sumit; Tabor, Rico F.; Singh, Ramesh; Bhattacharya, Amitabh

    2017-08-01

    We study the transportation of highly viscous furnace-oil in a horizontal pipe as core-annular flow (CAF) using experiments. Pressure drop and high-speed images of the fully developed CAF are recorded for a wide range of flow rate combinations. The height profiles (with respect to the centerline of the pipe) of the upper and lower interfaces of the core are obtained using a high-speed camera and image analysis. Time series of the interface height are used to calculate the average holdup of the oil phase, speed of the interface, and the power spectra of the interface profile. We find that the ratio of the effective velocity of the annular fluid to the core velocity, α , shows a large scatter. Using the average value of this ratio (α =0.74 ) yields a good estimate of the measured holdup for the whole range of flow rate ratios, mainly due to the low sensitivity of the holdup ratio to the velocity ratio. Dimensional analysis implies that, if the thickness of the annular fluid is much smaller than the pipe radius, then, for the given range of parameters in our experiments, the non-dimensional interface shape, as well as the non-dimensional wall shear stress, can depend only on the shear Reynolds number and the velocity ratio. Our experimental data show that, for both lower and upper interfaces, the normalized power spectrum of the interface height has a strong dependence on the shear Reynolds number. Specifically, for low shear Reynolds numbers, interfacial modes with large wavelengths dominate, while, for large shear Reynolds numbers, interfacial modes with small wavelengths dominate. Normalized variance of the interface height is higher at lower shear Reynolds numbers and tends to a constant with increasing shear Reynolds number. Surprisingly, our experimental data also show that the effective wall shear stress is, to a large extent, proportional to the square of the core velocity. Using the implied scalings for the holdup ratio and wall shear stress, we can derive

  18. Experimental Determination of Heat Transfer Coefficient in Two-phase Annular Flow

    Science.gov (United States)

    Dressler, Kristofer; Fehring, Brian; Morse, Roman; Livingston-Jha, Simon; Doherty, James; Chan, Jason; Brueggeman, Colby; Berson, Arganthael

    2017-11-01

    The goal of the presented work is to validate published mechanistic heat transfer models in two-phase annular flow under transient conditions. Annular flow occurs in many steam generation and refrigeration systems. Knowledge of the heat transfer coefficient (HTC) between the wall and the thin liquid film is critical to the design and safe operation of these systems. In heat exchangers with multiple parallel channels, thermal hydraulic instabilities often lead to unsteady flow conditions. The current study is performed in a facility capable of producing pulsed two-phase, single-species annular flow in a heated test section while simultaneously measuring local film thickness and wall temperature using non-intrusive optical techniques. Available correlations between the HTC and wall shear at steady state are compared to our measurements. The HTC can be derived from the known heating power and measured wall temperature, while wall shear is deduced from film thickness measurements. The validity of steady-state correlations under oscillating flow conditions is assessed by performing tests at a variety of pulse frequencies and amplitudes.

  19. The effect of sediment concentration on bedload roughness

    Science.gov (United States)

    Bergeron, Normand E.; Carbonneau, Patrice

    1999-11-01

    Bedload roughness is the roughness produced by sediment transported near the bed. While it is well established that the magnitude of this roughness is proportional to the thickness of the moving sediment layer, the effect of sediment concentration remains largely unknown. This paper presents the results of a flume experiment that was designed to investigate the effect of sediment concentration on bedload roughness. The experiment consisted of creating flow conditions where bedload transport is supply-limited and injecting gravel size particles (D50=7·4 mm) at the upstream end of the flume in order to produce bedload transport. While keeping flow conditions constant, sediment concentration was varied by successively increasing the injection rate of gravel in the flow. For each injection rate, flow velocity profiles were measured in order to evaluate changes of mean flow velocity U, shear velocity u*, roughness length zo and resistance to flow f. The results indicate that low sediment concentration affects mainly the near bed portion of the flow where it causes a reduction of mean flow velocity and an increase of shear velocity and roughness length. For larger sediment concentration, the whole flow velocity profile becomes affected by bedload roughness but the importance of this effect always remain larger near the bed. As sediment concentration is augmented, mean flow velocity is consistently reduced but shear velocity and roughness length increase until a plateau is reached where these two variables become constant.

  20. Annular feed air breathing fuel cell stack

    Science.gov (United States)

    Wilson, Mahlon S.

    1996-01-01

    A stack of polymer electrolyte fuel cells is formed from a plurality of unit cells where each unit cell includes fuel cell components defining a periphery and distributed along a common axis, where the fuel cell components include a polymer electrolyte membrane, an anode and a cathode contacting opposite sides of the membrane, and fuel and oxygen flow fields contacting the anode and the cathode, respectively, wherein the components define an annular region therethrough along the axis. A fuel distribution manifold within the annular region is connected to deliver fuel to the fuel flow field in each of the unit cells. In a particular embodiment, a single bolt through the annular region clamps the unit cells together. In another embodiment, separator plates between individual unit cells have an extended radial dimension to function as cooling fins for maintaining the operating temperature of the fuel cell stack.

  1. Phase retrieval on annular and annular sector pupils by using the eigenfunction method to solve the transport of intensity equation.

    Science.gov (United States)

    Huang, Shengyang; Xi, Fengjie; Liu, Changhai; Jiang, Zongfu

    2012-04-01

    Phase retrieval on an annular pupil and an annular sector pupil by using the eigenfunction method to solve the transport of intensity equation is proposed. The analytic expressions of Laplacian eigenfunctions with the Neumann boundary condition on an annular pupil and an annular sector pupil are given. The phase can be expanded as a set of eigenfunctions on the corresponding pupil, and the coefficients of the eigenfunctions can be obtained by the integral of the eigenfunction and the intensity derivative along the optical axis. Phase retrieval by the eigenfunction method on an annular pupil and an annular sector pupil is simulated, and accurate retrieved results are obtained.

  2. Optimal Thrust Vectoring for an Annular Aerospike Nozzle Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Recent success of an annular aerospike flight test by NASA Dryden has prompted keen interest in providing thrust vector capability to the annular aerospike nozzle...

  3. Spectrophotometric Examination of Rough Print Surfaces

    Directory of Open Access Journals (Sweden)

    Erzsébet Novotny

    2011-05-01

    Full Text Available The objective was to assess the impact of the surface texture of individual creative paper types (coated or patternedon the quality of printing and to identify to what extent the various creative paper types require specific types ofspectrophotometers. We used stereomicroscopic images to illustrate unprinted and printed surfaces of creative papertypes. Surface roughness was measured to obtain data on the unevenness of surfaces. Spectrophotometric tests wereused to select the most suitable spectrophotometer from meters with different illumination setup for testing anygiven print. For the purpose of testing, we used spectrophotometers which are commonly available generally used totest print products for colour accuracy. With the improvement of measuring geometries, illumination setup, colourmeasurement becomes more and more capable of producing reliable results unaffected by surface textures. Our testshave proved this fact by showing that the GretagMacbeth Spectrolino with annular illumination is less sensitive tosurface texture than the X-Rite Spetrodensitometer and the Techkon SpetroDens with directional illumination. Furthertests have brought us to the conclusion that there is a difference even between the two devices with directionalillumination. While the X-Rite 530 Spectrodensitometer is more suitable for testing coated surfaces, the TechkonSpectroDens can come close to ΔE*ab values produced by the annular illuminated device for textured surfaces.

  4. Turbulent thermal convection over rough surfaces

    Science.gov (United States)

    Stringano, G.; Verzicco, R.; Pascazio, G.

    2005-05-01

    Convective heat transport has important applications in engineering and meteorology and a better understanding of heat transport phenomena would lead to improvements in technological applications such as cooling of thermal machines and micro-electronic components or cooling during a metallurgical fusion. It would also improve the prediction of geophysical motions in oceans and atmosphere. The use of rough surfaces is a way to enhance the heat flux. The interaction between the main shear flow and the rough surface creates secondary vortices that enhance the detachment of thermal plumes from the tip of the rough elements. In this work numerical simulations are conducted in a cylindrical cell heated from below and cooled from above in presence of rough surfaces. A comparison of Rayleigh versus Nusselt number scaling between rough surfaces and smooth ones shows enhanced heat fluxes. The flow is solved using a direct numerical simulation (DNS) of the three dimensional unsteady Navier Stokes equations with the Boussinesq approximation and an immersed boundary approach is used for the treatment of rough surfaces.

  5. Shear of ordinary and elongated granular mixtures

    Science.gov (United States)

    Hensley, Alexander; Kern, Matthew; Marschall, Theodore; Teitel, Stephen; Franklin, Scott

    2015-03-01

    We present an experimental and computational study of a mixture of discs and moderate aspect-ratio ellipses under two-dimensional annular planar Couette shear. Experimental particles are cut from acrylic sheet, are essentially incompressible, and constrained in the thin gap between two concentric cylinders. The annular radius of curvature is much larger than the particles, and so the experiment is quasi-2d and allows for arbitrarily large pure-shear strains. Synchronized video cameras and software identify all particles and track them as they move from the field of view of one camera to another. We are particularly interested in the global and local properties as the mixture ratio of discs to ellipses varies. Global quantities include average shear rate and distribution of particle species as functions of height, while locally we investigate the orientation of the ellipses and non-affine events that can be characterized as shear transformational zones or possess a quadrupole signature observed previously in systems of purely circular particles. Discrete Element Method simulations on mixtures of circles and spherocylinders extend the study to the dynamics of the force network and energy dissipated as the system evolves. Supported by NSF CBET #1243571 and PRF #51438-UR10.

  6. Rough semigroups and rough fuzzy semigroups based on fuzzy ideals

    Directory of Open Access Journals (Sweden)

    Wang Qiumei

    2016-01-01

    Full Text Available In this paper, we firstly introduce a special congruence relation U(μ, t induced by a fuzzy ideal μ in a semigroup S. Then we define the lower and upper approximations based on a fuzzy ideal in semigroups. We can establish rough semigroups, rough ideals, rough prime ideals, rough fuzzy semigroups, rough fuzzy ideals and rough fuzzy prime ideals according to the definitions of rough sets and rough fuzzy sets. Furthermore, we shall consider the relationships among semigroups and rough semigroups, fuzzy semigroups and rough fuzzy semigroups, and some relative properties are also discussed.

  7. Direct numerical simulation of supercritical annular electroconvection

    NARCIS (Netherlands)

    Tsai, Peichun Amy; Daya, Zahir A.; Deyirmenjian, Vatche B.; Morris, Stephen W.

    2007-01-01

    We use direct numerical simulation to study electrically driven convection in an annular thin film. The simulation models a laboratory experiment that consists of a weakly conducting, submicron thick liquid crystal film suspended between two concentric electrodes. The film is driven to convect by

  8. Annular Pressure Seals and Hydrostatic Bearings

    National Research Council Canada - National Science Library

    San Andres, Luis

    2006-01-01

    ..., in particular those handling large density fluids. Highlights on the bulk-flow analysis of annular seals are given with details on the performance of two water seals long and short, featuring the advantages of an anti-swirl brake to enhance the seal...

  9. Periduodenal Tuberculosis masquerading as Annular Pancreas ...

    African Journals Online (AJOL)

    We report a patient who succumbed to an isolated mid duodenal tuberculosis, diagnosed at laparatomy, whose clinical presentation, endoscopy and computerised tomography scans resembled annular pancreas. The limitations of clinical evaluation, endoscopy and radiology are highlighted as the importance of diagnostic ...

  10. Annular beam with segmented phase gradients

    Directory of Open Access Journals (Sweden)

    Shubo Cheng

    2016-08-01

    Full Text Available An annular beam with a single uniform-intensity ring and multiple segments of phase gradients is proposed in this paper. Different from the conventional superposed vortices, such as the modulated optical vortices and the collinear superposition of multiple orbital angular momentum modes, the designed annular beam has a doughnut intensity distribution whose radius is independent of the phase distribution of the beam in the imaging plane. The phase distribution along the circumference of the doughnut beam can be segmented with different phase gradients. Similar to a vortex beam, the annular beam can also exert torques and rotate a trapped particle owing to the orbital angular momentum of the beam. As the beam possesses different phase gradients, the rotation velocity of the trapped particle can be varied along the circumference. The simulation and experimental results show that an annular beam with three segments of different phase gradients can rotate particles with controlled velocities. The beam has potential applications in optical trapping and optical information processing.

  11. Annular beam with segmented phase gradients

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Shubo; Wu, Liang [School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Tao, Shaohua, E-mail: eshtao@csu.edu.cn [School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China)

    2016-08-15

    An annular beam with a single uniform-intensity ring and multiple segments of phase gradients is proposed in this paper. Different from the conventional superposed vortices, such as the modulated optical vortices and the collinear superposition of multiple orbital angular momentum modes, the designed annular beam has a doughnut intensity distribution whose radius is independent of the phase distribution of the beam in the imaging plane. The phase distribution along the circumference of the doughnut beam can be segmented with different phase gradients. Similar to a vortex beam, the annular beam can also exert torques and rotate a trapped particle owing to the orbital angular momentum of the beam. As the beam possesses different phase gradients, the rotation velocity of the trapped particle can be varied along the circumference. The simulation and experimental results show that an annular beam with three segments of different phase gradients can rotate particles with controlled velocities. The beam has potential applications in optical trapping and optical information processing.

  12. Mechanical and hydraulic behavior of a rock fracture under shear deformation

    National Research Council Canada - National Science Library

    Nishiyama, Satoshi; Ohnishi, Yuzo; Ito, Hisao; Yano, Takao

    2014-01-01

    ...-scale hydraulic behavior. To this end, a simultaneous permeability and shear test device is developed, and shear-flow coupling tests are conducted on specimens having fractures with varied levels of surface roughness...

  13. Modeling of Inverted Annular Film Boiling using an integral method

    Science.gov (United States)

    Sridharan, Arunkumar

    In modeling Inverted Annular Film Boiling (IAFB), several important phenomena such as interaction between the liquid and the vapor phases and irregular nature of the interface, which greatly influence the momentum and heat transfer at the interface, need to be accounted for. However, due to the complexity of these phenomena, they were not modeled in previous studies. Since two-phase heat transfer equations and relationships rely heavily on experimental data, many closure relationships that were used in previous studies to solve the problem are empirical in nature. Also, in deriving the relationships, the experimental data were often extrapolated beyond the intended range of conditions, causing errors in predictions. In some cases, empirical correlations that were derived from situations other than IAFB, and whose applicability to IAFB was questionable, were used. Moreover, arbitrary constants were introduced in the model developed in previous studies to provide good fit to the experimental data. These constants have no physical basis, thereby leading to questionable accuracy in the model predictions. In the present work, modeling of Inverted Annular Film Boiling (IAFB) is done using Integral Method. Two-dimensional formulation of IAFB is presented. Separate equations for the conservation of mass, momentum and energy are derived from first principles, for the vapor film and the liquid core. Turbulence is incorporated in the formulation. The system of second-order partial differential equations is integrated over the radial direction to obtain a system of integral differential equations. In order to solve the system of equations, second order polynomial profiles are used to describe the nondimensional velocity and temperatures. The unknown coefficients in the profiles are functions of the axial direction alone. Using the boundary conditions that govern the physical problem, equations for the unknown coefficients are derived in terms of the primary dependent variables

  14. Bullous Pemphigoid Masquerading as Erythema Annulare Centrifugum.

    Science.gov (United States)

    Yu-Yang, Shiang; Chu-Sung Hu, Stephen; Yiao-Lin, Sheng

    2017-10-01

    Dear Editor, Bullous pemphigoid (BP), a relatively common autoimmune blistering disease in the elderly, is characterized by large, tense bullae on urticarial, erythematous, or normal skin. However, atypical BP with polymorphic clinical presentations is rarely encountered, leading to misdiagnosis and delayed treatments (1). BP with lesions resembling erythema gyratum repens or figurate erythema has been regarded as a paraneoplastic phenomenon (1). Herein we report a case with erythema annulare centrifugum-like presentation of BP without evidence of underlying malignancy. A 64-year-old woman first presented with multiple large, tense bullae on the trunk and four extremities. She was diagnosed with BP according to the typical clinical, histopathological, and direct immunofluorescence findings. There were no annular lesions at that time. After a treatment course of systemic corticosteroids and azathioprine, the cutaneous symptoms were controlled. One year after discontinuing her medications, a pruritic bullous eruption reappeared with several annular erythematous plaques (Figure 1, a). The patient reported no mucosal involvement and took no new medications before the onset of skin lesions. On physical examination, multiple circular and arcuate erythematous lesions with slightly raised borders were seen on the trunk and both legs. Some erosions and tiny vesicles were noted on the erythematous edges. There were no other systemic symptoms or abnormalities. Laboratory studies, including complete blood count, liver and renal function tests, electrolytes, antinuclear antibody, complement levels, anti-Ro and anti-La antibodies, urine routine, stool routine, and chest X-ray, were normal. The biopsy specimen obtained from the rim of the annular lesions revealed slight vacuolar change at the dermoepidermal junction and perivascular and interstitial lymphocytic infiltration with numerous eosinophils in the upper dermis (Figure 1, b). Direct immunofluorescence showed linear

  15. Simulation of non-Newtonian oil-water core annular flow through return bends

    Science.gov (United States)

    Jiang, Fan; Wang, Ke; Skote, Martin; Wong, Teck Neng; Duan, Fei

    2017-07-01

    The volume of fluid (VOF) model is used together with the continuum surface force (CSF) model to numerically simulate the non-Newtonian oil-water core annular flow across return bends. A comprehensive study is conducted to generate the profiles of pressure, velocity, volume fraction and wall shear stress for different oil properties, flow directions, and bend geometries. It is revealed that the oil core may adhere to the bend wall under certain operating conditions. Through the analysis of the total pressure gradient and fouling angle, suitable bend geometric parameters are identified for avoiding the risk of fouling.

  16. An annular gas seal analysis using empirical entrance and exit region friction factors

    Science.gov (United States)

    Elrod, D. A.; Childs, D. W.; Nelson, C. C.

    1990-01-01

    Wall shear stress results from stationary-rotor flow tests of five annular gas seals are used to develop entrance and exit region friction factor models. The friction factor models are used in a bulk-flow seal analysis which predicts leakage and rotor-dynamic coefficients. The predictions of the analysis are compared to experimental results and to the predictions of Nelson's analysis (1985). The comparisons are for smooth-rotor seals with smooth and honeycomb-stators. The present analysis predicts the destabilizing cross-coupled stiffness of a seal better than Nelson's analysis. Both analyses predict direct damping well and direct stiffness poorly.

  17. Hydraulic resistance in part-full pipes with composite roughness

    DEFF Research Database (Denmark)

    Perrusquia, G.; Petersen, O.; Larsen, Torben

    1994-01-01

    The paper discusses the boundary shear stresses and the hydraulic resistance in part-full sewer pipes with composite roughness. The discussion is based on a series of numerical experiments using a validated numerical turbulence model. The results from the numerical model are compared with the sid......The paper discusses the boundary shear stresses and the hydraulic resistance in part-full sewer pipes with composite roughness. The discussion is based on a series of numerical experiments using a validated numerical turbulence model. The results from the numerical model are compared...

  18. Systematic comparison of the use of annular and Zernike circle polynomials for annular wavefronts.

    Science.gov (United States)

    Mahajan, Virendra N; Aftab, Maham

    2010-11-20

    The theory of wavefront analysis of a noncircular wavefront is given and applied for a systematic comparison of the use of annular and Zernike circle polynomials for the analysis of an annular wavefront. It is shown that, unlike the annular coefficients, the circle coefficients generally change as the number of polynomials used in the expansion changes. Although the wavefront fit with a certain number of circle polynomials is identically the same as that with the corresponding annular polynomials, the piston circle coefficient does not represent the mean value of the aberration function, and the sum of the squares of the other coefficients does not yield its variance. The interferometer setting errors of tip, tilt, and defocus from a four-circle-polynomial expansion are the same as those from the annular-polynomial expansion. However, if these errors are obtained from, say, an 11-circle-polynomial expansion, and are removed from the aberration function, wrong polishing will result by zeroing out the residual aberration function. If the common practice of defining the center of an interferogram and drawing a circle around it is followed, then the circle coefficients of a noncircular interferogram do not yield a correct representation of the aberration function. Moreover, in this case, some of the higher-order coefficients of aberrations that are nonexistent in the aberration function are also nonzero. Finally, the circle coefficients, however obtained, do not represent coefficients of the balanced aberrations for an annular pupil. The various results are illustrated analytically and numerically by considering an annular Seidel aberration function.

  19. Umatilla - Rough Fish Eradication

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — In order to enhance environmental conditions in the McCormack Slough on Umatilla NWR, the population of rough fish, including common carp (Cyprinus carpio) and...

  20. Non newtonian annular alloy solidification in mould

    Energy Technology Data Exchange (ETDEWEB)

    Moraga, Nelson O.; Garrido, Carlos P. [Universidad de La Serena, Departamento de Ingenieria Mecanica, La Serena (Chile); Castillo, Ernesto F. [Universidad de Santiago de Chile, Departamento de Ingenieria Mecanica, Santiago (Chile)

    2012-08-15

    The annular solidification of an aluminium-silicon alloy in a graphite mould with a geometry consisting of horizontal concentric cylinders is studied numerically. The analysis incorporates the behavior of non-Newtonian, pseudoplastic (n=0.2), Newtonian (n=1), and dilatant (n=1.5) fluids. The fluid mechanics and heat transfer coupled with a transient model of convection diffusion are solved using the finite volume method and the SIMPLE algorithm. Solidification is described in terms of a liquid fraction of a phase change that varies linearly with temperature. The final results make it possible to infer that the fluid dynamics and heat transfer of solidification in an annular geometry are affected by the non-Newtonian nature of the fluid, speeding up the process when the fluid is pseudoplastic. (orig.)

  1. Non Newtonian annular alloy solidification in mould

    Science.gov (United States)

    Moraga, Nelson O.; Castillo, Ernesto F.; Garrido, Carlos P.

    2012-08-01

    The annular solidification of an aluminium-silicon alloy in a graphite mould with a geometry consisting of horizontal concentric cylinders is studied numerically. The analysis incorporates the behavior of non-Newtonian, pseudoplastic ( n = 0.2), Newtonian ( n = 1), and dilatant ( n = 1.5) fluids. The fluid mechanics and heat transfer coupled with a transient model of convection diffusion are solved using the finite volume method and the SIMPLE algorithm. Solidification is described in terms of a liquid fraction of a phase change that varies linearly with temperature. The final results make it possible to infer that the fluid dynamics and heat transfer of solidification in an annular geometry are affected by the non-Newtonian nature of the fluid, speeding up the process when the fluid is pseudoplastic.

  2. Anisotropic Spinodal Decomposition under Shear Flow

    Science.gov (United States)

    Imaeda, T.; Onuki, A.; Kawasaki, K.

    1984-01-01

    When a critical fluid is brought into the unstable region in the presence of shear flow, growing fluctuations are greatly elongated in the flow direction, giving rise to strongly anisotropic light scattering. In the strong shear case the linear growth theory becomes applicable in a sizable time region 0 Bar-on and Miller, it is found to increase as t(a') with a' =~ 0.2, whereas the characteristic size in the flow direction continues to increase roughly as t.

  3. Annular pancreas in adults (2 case reports.

    Directory of Open Access Journals (Sweden)

    Machado N

    1991-01-01

    Full Text Available Two cases of annular pancreas in adults are being reported. In the first case, a middle aged lady presented with duodenal obstruction and gastric ulcer. Anterior H. S. V. with posterior truncal vagotomy and isoperistaltic duodeno-jejunostomy relieved her symptoms. In the second case, a young girl presented with duodenal obstruction, severe wasting and gross dehydration. She had an uneventful recovery following a duodeno-jejunostomy.

  4. Annular feed air breathing fuel cell stack

    Science.gov (United States)

    Wilson, Mahlon S.; Neutzler, Jay K.

    1997-01-01

    A stack of polymer electrolyte fuel cells is formed from a plurality of unit cells where each unit cell includes fuel cell components defining a periphery and distributed along a common axis, where the fuel cell components include a polymer electrolyte membrane, an anode and a cathode contacting opposite sides of the membrane, and fuel and oxygen flow fields contacting the anode and the cathode, respectively, wherein the components define an annular region therethrough along the axis. A fuel distribution manifold within the annular region is connected to deliver fuel to the fuel flow field in each of the unit cells. The fuel distribution manifold is formed from a hydrophilic-like material to redistribute water produced by fuel and oxygen reacting at the cathode. In a particular embodiment, a single bolt through the annular region clamps the unit cells together. In another embodiment, separator plates between individual unit cells have an extended radial dimension to function as cooling fins for maintaining the operating temperature of the fuel cell stack.

  5. Crossover of the Thermal Escape Problem in Annular Spatially Distributed Systems

    Science.gov (United States)

    Fedorov, Kirill G.; Pankratov, Andrey L.

    2009-12-01

    The computer simulations of fluctuational dynamics of an annular system governed by the sine-Gordon model with a white noise source are performed. It is demonstrated that the mean escape time (MET) of a phase string for an annular structure can be much larger than for a linear one and has a strongly pronounced maximum as a function of system’s length. The location of the MET maximum roughly equals the size of the kink-antikink pair, which leads to evidence of a spatial crossover between two dynamical regimes: when the phase string escapes over the potential barrier as a whole and when the creation of kink-antikink pairs is the main mechanism of the escape process. For large lengths and in the limit of small noise intensity γ, for both MET and inverse concentration of kinks, we observe the same dependence versus the kink energy Ek: ˜exp⁡(2Ek/γ) for the annular structure and ˜exp⁡(Ek/γ) for the linear one.

  6. Experimental Investigation and Analysis of an Annular Pogo Accumulator

    Science.gov (United States)

    Peugeot, John; Schwarz, Jordan; Yang, H. Q.; Zoladz, Tom

    2011-01-01

    An experimental investigation was conducted on a scaled annular pogo accumulator for the Ares I Upper Stage. The test article was representative of the LO2 feedline and preliminary accumulator design, and included multiple designs of a perforated ring connecting the accumulator to the core feedline flow. The system was pulse tested in water over a range of pulse frequency and flow rates. Time dependent measurements of pressure at various locations in the test article were used to extract system compliance, inertance, and resistance. Preliminary results indicated a significant deviation from standard orifice flow theory and suggest a strong dependence on feedline average velocity. In addition, several CFD analyses were conducted to investigate the details of the time variant flow field. Both two-dimensional and three-dimensional simulations were performed with time varying boundary conditions used to represent system pulsing. The CFD results compared well with the sub-scale results and demonstrated the influence of feedline average velocity on the flow into and out of the accumulator. This paper presents updated results of the investigation including a parametric design space for determining resistance characteristics. Using the updated experimental results a new scaling relationship has been defined for shear flow over a cavity. A comparison of sub-scale and full scale CFD simulations provided early verification of the scaling of the fluid flowfield and resistance characteristics.

  7. Stability of three-layered core-annular flow

    Science.gov (United States)

    Pillai, Dipin; Pushpavanam, Subramaniam; Sundararajan, T.

    2016-11-01

    Stability of a three-layered core-annular flow is analyzed using the method of modal linear stability analysis. A temporal analysis shows that the flow becomes unstable to two modes of instability when inertial effects are negligible. An energy budget analysis reveals that these two modes correspond to capillary instability associated with each fluid-fluid interface. With an increase in Reynolds number, the system exhibits additional Reynolds stress modes of instabilities. These modes correspond to the Tollmien-Schlichting type of waves associated with high Reynolds number shear flows, and are considered precursor to transition to turbulence. An investigation of the parameter space reveals that the system may simultaneously show up to 5 distinct modes of instability, viz., the two capillary modes at each interface and three Reynolds stress modes in the bulk of each phase. In addition, a spatio-temporal analysis shows that the Reynolds stress modes are always convectively unstable whereas the capillary modes may undergo a transition from convective to absolute instability with decrease in Weber number. To obtain encapsulated droplets in experiments, the operating parameters must be chosen such that the system lies in the regime of convective instability. MHRD-Govt of India, NSF 0968313.

  8. Novel annular flow electromagnetic measurement system for drilling engineering.

    OpenAIRE

    Ge, L.; Wei, G.H.; Wang, Q; Hu,Z.; Li, J. L.

    2017-01-01

    Downhole micro-flux control drilling technology can effectively solve drilling accidents, such as kick and loss in narrow density window drilling scenarios. Using a downhole annular flow measurement system to obtain real-time information of downhole annular flow is the core and foundation of downhole micro-flux control drilling technology. The research work of electromagnetic flowmeters in recent years creates a challenge for downhole annular flow measurement. This paper proposes a new method...

  9. Granuloma annulare localized to the shaft of the penis

    DEFF Research Database (Denmark)

    Trap, R; Wiebe, B

    1993-01-01

    A case of granuloma annulare localized to the shaft of the penis is reported. The differential diagnoses are discussed. Penile granuloma annulare is a rare disorder and it is concluded that biopsies of penile lesions are recommended to verify the correct diagnosis.......A case of granuloma annulare localized to the shaft of the penis is reported. The differential diagnoses are discussed. Penile granuloma annulare is a rare disorder and it is concluded that biopsies of penile lesions are recommended to verify the correct diagnosis....

  10. Scanning near-field optical microscopy on rough surfaces: Applications in chemistry, biology, and medicine

    OpenAIRE

    Kaupp, Gerd

    2006-01-01

    Shear-force apertureless scanning near-field optical microscopy (SNOM) with very sharp uncoated tapered waveguides relies on the unexpected enhancement of reflection in the shear-force gap. It is the technique for obtaining chemical (materials) contrast in the optical image of “real world” surfaces that are rough and very rough without topographical artifacts, and it is by far less complicated than other SNOM techniques that can only be used for very flat surfaces. The ex...

  11. Wave turbulence in annular wave tank

    Science.gov (United States)

    Onorato, Miguel; Stramignoni, Ettore

    2014-05-01

    We perform experiments in an annular wind wave tank at the Dipartimento di Fisica, Universita' di Torino. The external diameter of the tank is 5 meters while the internal one is 1 meter. The tank is equipped by two air fans which can lead to a wind of maximum 5 m/s. The present set up is capable of studying the generation of waves and the development of wind wave spectra for large duration. We have performed different tests including different wind speeds. For large wind speed we observe the formation of spectra consistent with Kolmogorv-Zakharov predictions.

  12. current modelling in annular porous electrodes

    Directory of Open Access Journals (Sweden)

    T. W. Farrell

    2001-01-01

    Full Text Available An equivalent circuit for an annular porous electrode is derived by reinterpreting the differential equations that approximate the distribution of voltage and current in such electrodes. The equivalent circuit is shown to provide useful physical interpretations of the secondary current distributions. Multi-loop circuit techniques are employed to obtain the current distributions within the circuit. The solutions are shown to compare well with the exact solutions of the model equations. In addition, the equivalent circuit approach is used to investigate the effect of curvature on the degree of polarization of the electrode.

  13. EXPLOSION OF ANNULAR CHARGE ON DUSTY SURFASE

    Directory of Open Access Journals (Sweden)

    A. Levin Vladimir

    2017-01-01

    Full Text Available This problem is related to the safety problem in the area of forest fires. It is well known that is possible to extinguish a fire, for example, by means of a powerful air stream. Such flow arises from the explosive shock wave. To enhance the im- pact of the blast wave can be used an explosive charge of annular shape. The shock wave, produced by the explosion, in- creased during moves to the center and can serve as a means of transportation dust in the seat of the fire. In addition, emerging after the collapse of a converging shock wave strong updraft can raise dust on a greater height and facilitate fire extinguishing, precipitating dust over a large area. This updraft can be dangerous for aircraft that are in the sky above the fire. To determine the width and height of the danger zone performed the numerical simulation of the ring of the explosion and the subsequent movement of dust and gas mixtures. The gas is considered ideal and perfect. The explosion is modeled as an instantaneous increase in the specific internal energy in an annular zone on the value of the specific heat of explosives. The flow is consid- ered as two-dimensional, and axisymmetric. The axis of symmetry perpendicular to the Earth surface. This surface is considered to be absolutely rigid and is considered as the boundary of the computational domain. On this surface is exhibited the condition of no motion. For the numerical method S. K. Godunov is used a movable grid. One system of lines of this grid is moved in accordance with movement of the shock wave. Others lines of this grid are stationary. The calculations were per- formed for different values of the radii of the annular field and for different sizes of rectangular cross-sectional of the annular field. Numerical results show that a very strong flow is occurring near the axis of symmetry and the particles rise high above the surface. These calculations allow us to estimate the sizes of the zone of danger in specific

  14. Deep variant of Erythema Annulare Centrifugum

    Directory of Open Access Journals (Sweden)

    Ahu Yorulmaz

    2014-10-01

    Full Text Available A 29-year-old woman came to our outpatient clinic with a several-month history of itchy red lesions over her trunk. There was no family history and past history of any other diseases or medication. Dermatological examination revealed annular and oval-shaped plaques up to several cm’s in size, one of which was polycyclic in configuration, on back of the patient (Fig. 1. It was also noticed that lesions had erythematous indurated bordes with paler central areas (Fig. 1.

  15. Annular Lupus Vulgaris Mimicking Tinea Cruris

    Science.gov (United States)

    Heo, Young Soo; Shin, Won Woong; Kim, Yong Ju; Song, Hae Jun

    2010-01-01

    Cutaneous tuberculosis is an infrequent form of extrapulmonary tuberculosis. It is often clinically and histopathologically confused with various cutaneous disorders. A 36-year-old man attended our clinic with slowly progressive, asymptomatic, annular skin lesions on both the thighs and buttocks for 10 years. He consulted with many physicians and was improperly treated with an oral antifungal agent for several months under the diagnosis of tinea cruris, but no resolution of his condition was observed. A diagnosis of lupus vulgaris was made based on the histopathologic examination and the polymerase chain reaction assay. Anti-tuberculosis therapy was administered and the lesions started to regress. PMID:20548922

  16. Fluxon Dynamics in Elliptic Annular Josephson Junctions

    DEFF Research Database (Denmark)

    Monaco, Roberto; Mygind, Jesper

    2016-01-01

    We analyze the dynamics of a magnetic flux quantum (current vortex) trapped in a current-biased long planar elliptic annular Josephson tunnel junction. The system is modeled by a perturbed sine-Gordon equation that determines the spatial and temporal behavior of the phase difference across...... the tunnel barrier separating the two superconducting electrodes. In the absence of an external magnetic field, the fluxon dynamics in an elliptic annulus does not differ from that of a circular annulus where the stationary fluxon speed merely is determined by the system losses. The interaction between...

  17. Rough-to-smooth transition of an equilibrium neutral constant stress layer. [atmospheric flow over rough terrain

    Science.gov (United States)

    Logan, E., Jr.; Fichtl, G. H.

    1975-01-01

    A model is proposed for low-level atmospheric flows over terrains of changing roughness length, such as those found at the windward end of landing strips adjoining rough terrain. The proposed model is used to develop a prediction technique for calculating transition wind and shear-stress profiles in the region following surface roughness discontinuity. The model for the transition region comprises two layers: a logarithmic layer and a buffer layer. The flow is assumed to be steady, two-dimensional, and incompressible, with neutral hydrostatic stability. A diagram is presented for a typical wind profile in the transition region, obtained from the logarithmic and velocity defect profiles using shear stress calculated by relevant equations.

  18. The second annular pulley: a histologic examination.

    Science.gov (United States)

    Ellis, F D; Seiler, J G; Sewell, C W

    1995-07-01

    The second annular pulley and underlying flexor tendons from 15 fresh frozen fingers were prepared, sectioned transversely and longitudinally and then stained with hematoxylin-eosin, Verhoeff-Van Gieson (Elastin), Masson's trichrome and for the presence of hyaluronic acid. Three discrete layers of the second annular pulley were identified (1) an outer layer, continuous with the membranous sheath, that was richly vascularized; (2) a middle layer, characterized by radially oriented collagen fibrils and significant elastin fibrils; (3) an inner gliding surface, characterized by longitudinally oriented collagen fibrils and modified fibroblasts secreting hyaluronic acid. The three layers of the pulley seem specialized and have developed based on the functional requirements of the pulley apparatus. The outer layer serves as a source of vascular supply and nutrition, the middle layer maintains structural integrity and is organized to efficiently resist flexor tendon bowstringing, and the innermost layer facilitates efficient excursion of the underlying flexor tendons both by the orientation of the collagen fibers and by the secretion of substances that are thought to minimize friction.

  19. Limited Diffraction Maps for Pulsed Wave Annular Arrays

    DEFF Research Database (Denmark)

    Fox, Paul D.

    2002-01-01

    A procedure is provided for decomposing the linear field of flat pulsed wave annular arrays into an equivalent set of known limited diffraction Bessel beams. Each Bessel beam propagates with known characteristics, enabling good insight into the propagation of annular fields to be obtained...

  20. 75 FR 23582 - Annular Casing Pressure Management for Offshore Wells

    Science.gov (United States)

    2010-05-04

    ... Recommended Practice (RP) 90. As explained in API RP 90, Section 3, Annular Casing Pressure Management Program... that are problematic. The management program, as outlined in API RP 90, includes monitoring, diagnostic.... * * * * * (h) * * * (78) API RP 90, Annular Casing Pressure Management for Offshore Wells, First Edition...

  1. Sediment transport in the presence of large reef bottom roughness

    Science.gov (United States)

    Pomeroy, Andrew W. M.; Lowe, Ryan J.; Ghisalberti, Marco; Storlazzi, Curt; Symonds, Graham; Roelvink, Dano

    2017-02-01

    The presence of large bottom roughness, such as that formed by benthic organisms on coral reef flats, has important implications for the size, concentration, and transport of suspended sediment in coastal environments. A 3 week field study was conducted in approximately 1.5 m water depth on the reef flat at Ningaloo Reef, Western Australia, to quantify the cross-reef hydrodynamics and suspended sediment dynamics over the large bottom roughness (˜20-40 cm) at the site. A logarithmic mean current profile consistently developed above the height of the roughness; however, the flow was substantially reduced below the height of the roughness (canopy region). Shear velocities inferred from the logarithmic profile and Reynolds stresses measured at the top of the roughness, which are traditionally used in predictive sediment transport formulations, were similar but much larger than that required to suspend the relatively coarse sediment present at the bed. Importantly, these stresses did not represent the stresses imparted on the sediment measured in suspension and are therefore not relevant to the description of suspended sediment transport in systems with large bottom roughness. Estimates of the bed shear stresses that accounted for the reduced near-bed flow in the presence of large roughness vastly improved the relationship between the predicted and observed grain sizes that were in suspension. Thus, the impact of roughness, not only on the overlying flow but also on bed stresses, must be accounted for to accurately estimate suspended sediment transport in regions with large bottom roughness, a common feature of many shallow coastal ecosystems.

  2. Sediment transport in the presence of large reef bottom roughness

    Science.gov (United States)

    Pomeroy, Andrew; Lowe, Ryan J.; Ghisalberti, Marco; Storlazzi, Curt; Symonds, Graham; Roelvink, Dano

    2017-01-01

    The presence of large bottom roughness, such as that formed by benthic organisms on coral reef flats, has important implications for the size, concentration, and transport of suspended sediment in coastal environments. A 3 week field study was conducted in approximately 1.5 m water depth on the reef flat at Ningaloo Reef, Western Australia, to quantify the cross-reef hydrodynamics and suspended sediment dynamics over the large bottom roughness (∼20–40 cm) at the site. A logarithmic mean current profile consistently developed above the height of the roughness; however, the flow was substantially reduced below the height of the roughness (canopy region). Shear velocities inferred from the logarithmic profile and Reynolds stresses measured at the top of the roughness, which are traditionally used in predictive sediment transport formulations, were similar but much larger than that required to suspend the relatively coarse sediment present at the bed. Importantly, these stresses did not represent the stresses imparted on the sediment measured in suspension and are therefore not relevant to the description of suspended sediment transport in systems with large bottom roughness. Estimates of the bed shear stresses that accounted for the reduced near-bed flow in the presence of large roughness vastly improved the relationship between the predicted and observed grain sizes that were in suspension. Thus, the impact of roughness, not only on the overlying flow but also on bed stresses, must be accounted for to accurately estimate suspended sediment transport in regions with large bottom roughness, a common feature of many shallow coastal ecosystems.

  3. The effect of roughness on biophysical stimuli at the bone-cartilage interface.

    Science.gov (United States)

    Beilin, Vadim; Ito, Keita; Pande, Gyan N

    2003-09-01

    Numerical simulations are often used to investigate the effect of mechanical environment on fracture healing. Although these models exhibit biologically relevant mechanical parameters at the bone-callus interface, this interface is modelled as perfectly smooth when in fact it is rough. In this study, a macro-micro-two-scale finite element model was used to determine if roughness significantly alters calculated local mechanical parameters. An idealized fracture healing poroelastic model with a small micro-modelled sub-domain of cartilaginous callus adjacent to rough bone was subjected to cyclic loading. The shear stress, tangential fluid velocity, and pore pressure were investigated. With roughness similar to that at the growth plate, solid matrix shear stress differed substantially with interface roughness, whereas interstitial fluid velocity and pore pressure were only slightly affected. Hence, when modelling local micro-mechanical environments near hard-soft tissue interfaces, interface roughness should be considered.

  4. Skin-pass rolling I – Studies on roughness transfer and elongation under pure normal loading

    DEFF Research Database (Denmark)

    Kijima, Hideo; Bay, Niels

    2008-01-01

    The influence of tool roughness in skin-pass or temper rolling of steel strip is investigated focusing on roughness transfer and strip elongation under pure normal loading, i.e. with no tangential shear between tool and workpiece. The process is simulated by an elasto-plastic FE simulation of pla...

  5. Annular pancreas intra operatively discovered: a case report

    Directory of Open Access Journals (Sweden)

    Zeineb Mzoughi

    2011-10-01

    Full Text Available Annular pancreas is a rare congenital abnormality. This entity can rarely be symptomatic. Patients can present with gastrointestinal obstruction or acute pancreatitis. We report a case with a rich iconography, of an annular pancreas discovered intraoperatively. A 46- year-old woman was operated with the diagnosis of acute cholecystitis with common bile duct stones. At operation, a strip of pancreatic tissue (2 cm completely encircled the second duodenum. Open cholecytectomy with choledocotomy and stones extractionwas done. Postoperatively, she developed an acute pancreatitis. The post-operative cholangiography showed the annular duct surrounding the second duodenum. Annular pancreas is rare. Symptoms may occur in newborn children. In adults, annular pancreas discovering is radiological or intra operatively.

  6. Turbulent structure at the midsection of an annular flow

    Science.gov (United States)

    Ghaemi, S.; Rafati, S.; Bizhani, M.; Kuru, E.

    2015-10-01

    The turbulent flow in the midsection of an annular gap between two concentric tubes at Reynolds number of 59 200-90 800 based on hydraulic diameter (dh = 57 mm) and average velocity is experimentally investigated. Measurements are carried out using particle tracking velocimetry (PTV) and planar particle image velocimetry (PIV) with spatial resolution of 0.0068dh (size of the binning window) and 0.0129dh (size of the interrogation window), respectively. Both PTV and PIV results show that the location of maximum mean streamwise velocity (yU) does not coincide with the locations of zero shear stress (yuv), minimum streamwise velocity fluctuation (yu2), and minimum radial velocity fluctuation (yv2). The separation between yU and yuv is 0.013dh based on PTV while PIV underestimates the separation distance as 0.0063dh. Conditional averages of turbulent fluctuations based on the four quadrants across the annulus demonstrate that the inner and outer wall flows overlap in the midsection. In the midsection, the flow is subject to opposing sweep/ejection events originating from both the inner and outer walls. The opposite quadrant events of the two boundary layers cancel out at yuv while the local minimum of spatial correlation of u (maximum mixing of the two wall flows) occurs at yU. Investigation of the budget of Reynolds shear stress showed that production and advection terms act towards the coincidence of the yU and yuv while the dissipation term works against the coincidence of the two points. The location of max also overlaps with zero dissipation of . The production of turbulent kinetic energy is slightly negative in the narrow region between yU and yuv. This negative production acts towards smoothing the mean velocity profile at the joint of the two wall flows by equalizing its curvature (∂2/∂y2) on the two sides of yU. The small separation distance of the yU and yuv is associated with slight deviation from the fully developed condition.

  7. QUENCH FRONT PROPAGATION IN THE ANNULAR CHANNEL

    Directory of Open Access Journals (Sweden)

    Jan Stepanek

    2016-12-01

    Full Text Available Understanding the quench front propagation during bottom core reflooding is crucial for the effective cooling during the LOCA accident. The results presented in this paper were obtained on an experimental loop with an annular test section. The test section consists of a vertical electrically heated stainless steel tube with outer diameter 9 mm and length of 1.7 m. The heated tube is placed inside a glass tube with the inner diameter 14.5 mm. Water mass flux during the reflooding is in the range from 100 kg.m−2.s−1 up to 140 kg.m−2.s−1 and the initial wall temperature of the stainless steel tube is in the range from 250 °C up to 800 °C. The presented results show the influence of the initial conditions on the quench front propagation and the complexity of the phenomenon.

  8. Study on surface roughness evolvement of Nd-doped phosphate glass after IBF

    Science.gov (United States)

    Li, Furen; Xie, Xuhui; Zhou, Lin; Tie, Guipeng; Hu, Hao

    2016-10-01

    Nd doped phosphate glass is widely used as gain media in high power laser system. It is traditionally polished with the annular polishing technology. The edge effect is inevitable in annular polishing process and it results in the low manufacturing efficiency. Ion Beam Figuring (IBF) is a highly deterministic, non-contact method for the ultra-precision optics fabrication. So the edge effect is avoided. Nanometer and sub-nanometer precision is realizable in IBF. In this paper, Nd doped phosphate glass was polished with IBF, and the evolvement of surface roughness was emphasized. The roughness of surface polished with ion beam at normal and oblique incidence was researched. The oblique incident angle was 45°. The surface roughness was measured with the white light interferometer. No evident change was observed. This means that the pre-finish roughness can be preserved in IBF. The results denote that IBF is a feasible method to correct the contour errors of Nd doped phosphate glass, and the roughness will not be coarsened.

  9. Annular MHD Physics for Turbojet Energy Bypass

    Science.gov (United States)

    Schneider, Steven J.

    2011-01-01

    The use of annular Hall type MHD generator/accelerator ducts for turbojet energy bypass is evaluated assuming weakly ionized flows obtained from pulsed nanosecond discharges. The equations for a 1-D, axisymmetric MHD generator/accelerator are derived and numerically integrated to determine the generator/accelerator performance characteristics. The concept offers a shockless means of interacting with high speed inlet flows and potentially offers variable inlet geometry performance without the complexity of moving parts simply by varying the generator loading parameter. The cycle analysis conducted iteratively with a spike inlet and turbojet flying at M = 7 at 30 km altitude is estimated to have a positive thrust per unit mass flow of 185 N-s/kg. The turbojet allowable combustor temperature is set at an aggressive 2200 deg K. The annular MHD Hall generator/accelerator is L = 3 m in length with a B(sub r) = 5 Tesla magnetic field and a conductivity of sigma = 5 mho/m for the generator and sigma= 1.0 mho/m for the accelerator. The calculated isentropic efficiency for the generator is eta(sub sg) = 84 percent at an enthalpy extraction ratio, eta(sub Ng) = 0.63. The calculated isentropic efficiency for the accelerator is eta(sub sa) = 81 percent at an enthalpy addition ratio, eta(sub Na) = 0.62. An assessment of the ionization fraction necessary to achieve a conductivity of sigma = 1.0 mho/m is n(sub e)/n = 1.90 X 10(exp -6), and for sigma = 5.0 mho/m is n(sub e)/n = 9.52 X 10(exp -6).

  10. Roughing up Beta

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Li, Sophia Zhengzi; Todorov, Viktor

    -section. An investment strategy that goes long stocks with high jump betas and short stocks with low jump betas produces significant average excess returns. These higher risk premiums for the discontinuous and overnight market betas remain significant after controlling for a long list of other firm characteristics......-section of expected returns. Based on a novel highfrequency dataset of almost one-thousand individual stocks over two decades, we find that the two rough betas associated with intraday discontinuous and overnight returns entail significant risk premiums, while the intraday continuous beta is not priced in the cross...... and explanatory variables previously associated with the cross-section of expected stock returns....

  11. Modelling dynamic roughness during floods

    NARCIS (Netherlands)

    Paarlberg, Andries; Dohmen-Janssen, Catarine M.; Hulscher, Suzanne J.M.H.; Termes, A.P.P.

    2007-01-01

    In this paper, we present a dynamic roughness model to predict water levels during floods. Hysteresis effects of dune development are explicitly included. It is shown that differences between the new dynamic roughness model, and models where the roughness coefficient is calibrated, are most

  12. Pavement roughness and skid properties

    Science.gov (United States)

    Road roughness and roadway safety as it relates to both surface and air transportation are discussed. The role of road roughness in vehicle ride, the measurement of roughness, the evaluation of riding confort, and the effect of grooving pavements are discussed. The effects of differential pavement friction on the response of cars in skidding maneuvers is discussed.

  13. Phase-locking of annular-combination CO2 laser

    Science.gov (United States)

    Qi, Tingxiang; Chen, Mei; Zhang, Rongzhu; Xiao, Qianyi

    2015-07-01

    A new annular-combination resonator structure adopting the external-injection phase-locking technology is presented theoretically for that the beam quality of stable annular resonator is not satisfying. The phase-locking principle and feasibility are characterized by energy density of injection beam and coupling coefficient. Based on the diffraction theory, output mode of the resonator with phase-locking is deduced and simulated. Results also confirm that injection beam have a good control effect on output mode. The intensity distributions of output beam are studied briefly and indicate that this new resonator which is adaptable to annular gain media can produce high-power laser beam with high quality.

  14. An Experimental Study of Swirling Flows as Applied to Annular Combustors

    Science.gov (United States)

    Seal, Michael Damian, II

    1997-01-01

    This thesis presents an experimental study of swirling flows with direct applications to gas turbine combustors. Two separate flowfields were investigated: a round, swirling jet and a non-combusting annular combustor model. These studies were intended to allow both a further understanding of the behavior of general swirling flow characteristics, such as the recirculation zone, as well as to provide a base for the development of computational models. In order to determine the characteristics of swirling flows the concentration fields of a round, swirling jet were analyzed for varying amount of swirl. The experimental method used was a light scattering concentration measurement technique known as marker nephelometry. Results indicated the formation of a zone of recirculating fluid for swirl ratios (rotational speed x jet radius over mass average axial velocity) above a certain critical value. The size of this recirculation zone, as well as the spread angle of the jet, was found to increase with increase in the amount of applied swirl. The annular combustor model flowfield simulated the cold-flow characteristics of typical current annular combustors: swirl, recirculation, primary air cross jets and high levels of turbulence. The measurements in the combustor model made by the Laser Doppler Velocimetry technique, allowed the evaluation of the mean and rms velocities in the three coordinate directions, one Reynold's shear stress component and the turbulence kinetic energy: The primary cross jets were found to have a very strong effect on both the mean and turbulence flowfields. These cross jets, along with a large step change in area and wall jet inlet flow pattern, reduced the overall swirl in the test section to negligible levels. The formation of the strong recirculation zone is due mainly to the cross jets and the large step change in area. The cross jets were also found to drive a four-celled vortex-type motion (parallel to the combustor longitudinal axis) near the

  15. Notions of Rough Neutrosophic Digraphs

    Directory of Open Access Journals (Sweden)

    Nabeela Ishfaq

    2018-01-01

    Full Text Available [-3]Graph theory has numerous applications in various disciplines, including computer networks, neural networks, expert systems, cluster analysis, and image capturing. Rough neutrosophic set (NS theory is a hybrid tool for handling uncertain information that exists in real life. In this research paper, we apply the concept of rough NS theory to graphs and present a new kind of graph structure, rough neutrosophic digraphs. We present certain operations, including lexicographic products, strong products, rejection and tensor products on rough neutrosophic digraphs. We investigate some of their properties. We also present an application of a rough neutrosophic digraph in decision-making.

  16. Direct numerical simulation of turbulent core-annular flow in a vertical pipe

    Science.gov (United States)

    Kim, Kiyoung; Choi, Haecheon

    2014-11-01

    The core-annular flow has been considered as a useful tool to effectively transport highly viscous oil by having lower viscous fluid such as water near the pipe surface. There have been several studies to investigate turbulent core-annular flows but most of them have been conducted experimentally. We solve the three-dimensional Navier-Stokes equations in a cylindrical coordinate and use the level-set method for interface tracking between two fluids (oil and water). A few different flow parameters such as the superficial velocity of fluids and mean pressure gradient are considered in a vertical pipe. The results show that the oil core region is nearly a plug flow and the water region experiences high shear rates, which generate turbulence structures different from those of single phase flow. The interface wave suppresses the near-wall coherent structures but produces complex fluid motions caused by its interaction with the wall. The phenomenon of maximum drag reduction and the effect of water turbulence on total drag will be discussed at the presentation. We gratefully acknowledge financial support from the NRF Programs (No. 2012M2A8A4055647), Mest, Korea.

  17. IMAGE ANALYSIS FOR MODELLING SHEAR BEHAVIOUR

    Directory of Open Access Journals (Sweden)

    Philippe Lopez

    2011-05-01

    Full Text Available Through laboratory research performed over the past ten years, many of the critical links between fracture characteristics and hydromechanical and mechanical behaviour have been made for individual fractures. One of the remaining challenges at the laboratory scale is to directly link fracture morphology of shear behaviour with changes in stress and shear direction. A series of laboratory experiments were performed on cement mortar replicas of a granite sample with a natural fracture perpendicular to the axis of the core. Results show that there is a strong relationship between the fracture's geometry and its mechanical behaviour under shear stress and the resulting damage. Image analysis, geostatistical, stereological and directional data techniques are applied in combination to experimental data. The results highlight the role of geometric characteristics of the fracture surfaces (surface roughness, size, shape, locations and orientations of asperities to be damaged in shear behaviour. A notable improvement in shear understanding is that shear behaviour is controlled by the apparent dip in the shear direction of elementary facets forming the fracture.

  18. Principle of radial transport in low temperature annular plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yunchao, E-mail: yunchao.zhang@anu.edu.au; Charles, Christine; Boswell, Rod [Space Plasma, Power and Propulsion Laboratory, Research School of Physics and Engineering, The Australian National University, Bldg 60, Mills Road, Australian Capital Territory 2601 (Australia)

    2015-07-15

    Radial transport in low temperature annular plasmas is investigated theoretically in this paper. The electrons are assumed to be in quasi-equilibrium due to their high temperature and light inertial mass. The ions are not in equilibrium and their transport is analyzed in three different situations: a low electric field (LEF) model, an intermediate electric field (IEF) model, and a high electric field (HEF) model. The universal IEF model smoothly connects the LEF and HEF models at their respective electric field strength limits and gives more accurate results of the ion mobility coefficient and effective ion temperature over the entire electric field strength range. Annular modelling is applied to an argon plasma and numerical results of the density peak position, the annular boundary loss coefficient and the electron temperature are given as functions of the annular geometry ratio and Paschen number.

  19. Stationary core-annular flow through a horizontal pipe.

    Science.gov (United States)

    Ooms, G; Poesio, P

    2003-12-01

    A theoretical investigation has been made of core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity annular liquid layer through a horizontal pipe. Special attention is paid to the question how the buoyancy force on the core, caused by a possible density difference between the core and the annular layer, is counterbalanced. From earlier studies it is known that at the core surface ripples are present that have the shape of "bamboo" waves or "snake" waves. They generate pressure variations and secondary flows in the annular layer that can cause a net hydrodynamic force on the core. Using hydrodynamic-lubrication theory (assuming the core to be rigid) it has been shown that for snake waves the lubrication force can counterbalance the buoyancy force. For bamboo waves that is not the case.

  20. Velocity shear generation of solar wind turbulence

    Science.gov (United States)

    Roberts, D. A.; Goldstein, Melvyn L.; Matthaeus, William H.; Ghosh, Sanjoy

    1992-01-01

    A two-dimensional incompressible MHD spectral code is used to show that shear-driven turbulence is a possible means for producing many observed properties of the evolution of the magnetic and velocity fluctuations in the solar wind and, in particular, the evolution of the cross helicity ('Alfvenicity') at small scales. It is shown that large-scale shear can nonlinearly produce a cascade to smaller scale fluctuations even when the linear Kelvin-Helmholtz mode is stable, and that a roughly power law inertial range is established by this process. The evolution found is similar to that seen in some other simulations of MHD turbulence.

  1. Rough Surface Contact

    Directory of Open Access Journals (Sweden)

    T Nguyen

    2017-06-01

    Full Text Available This paper studies the contact of general rough curved surfaces having nearly identical geometries, assuming the contact at each differential area obeys the model proposed by Greenwood and Williamson. In order to account for the most general gross geometry, principles of differential geometry of surface are applied. This method while requires more rigorous mathematical manipulations, the fact that it preserves the original surface geometries thus makes the modeling procedure much more intuitive. For subsequent use, differential geometry of axis-symmetric surface is considered instead of general surface (although this “general case” can be done as well in Chapter 3.1. The final formulas for contact area, load, and frictional torque are derived in Chapter 3.2.

  2. Forced convection to laminar flow of liquid egg yolk in circular and annular ducts

    Directory of Open Access Journals (Sweden)

    M. Bernardi

    2009-06-01

    Full Text Available The steady-state heat transfer in laminar flow of liquid egg yolk - an important pseudoplastic fluid food - in circular and concentric annular ducts was experimentally investigated. The average convection heat transfer coefficients, determined by measuring temperatures before and after heating sections with constant temperatures at the tube wall, were used to obtain simple new empirical expressions to estimate the Nusselt numbers for fully established flows at the thermal entrance of the considered geometries. The comparisons with existing correlations for Newtonian and non-Newtonian fluids resulted in excellent agreement. The main contribution of this work is to supply practical and easily applicable correlations, which are, especially for the case of annulus, rather scarce and extensively required in the design of heat transfer operations dealing with similar shear-thinning products. In addition, the experimental results may support existing theoretical analyses.

  3. Successful treatment of annular rupture during transcatheter aortic valve implantation.

    Science.gov (United States)

    Unic, Daniel; Sutlic, Zeljko; Starcevic, Boris; Bradic, Nikola; Baric, Davor; Rudez, Igor

    2017-04-01

    Annular rupture presents a rare but potentially fatal complication of transcatheter aortic valve implantation (TAVI). Although it can be subtle and subclinical in presentation, most severe forms present with hemodynamic instability and represent true emergencies requiring a more invasive treatment, even conventional surgery. We present a case of successful treatment of annular rupture by left ventricular outflow tract patch and surgical aortic valve replacement.

  4. Cone Penetrometer Shear Strength Measurements of Sludge Waste in Tanks 241-AN-101 and 241-AN-106

    Energy Technology Data Exchange (ETDEWEB)

    Follett, Jordan R.

    2014-03-06

    This document presents the resulting shear strength profiles for sludge waste in Tanks 241-AN-101 and 241-AN-106, as determined with a full-flow cone penetrometer. Full-flow penetrometer measurements indicate shear strength profiles that increase roughly uniformly with depth. For Tank 241-AN-101, the undrained shear strength was calculated to range from 500 Pa near the sludge surface to roughly 3,300 Pa at 15 inches above the tank bottom. For 241-AN-106, the undrained shear strength was calculated to range from 500 Pa near the sludge surface to roughly 5,000 Pa at 15 inches above the tank bottom.

  5. Disfiguring Annular Sarcoidosis Improved by Adalimumab

    Directory of Open Access Journals (Sweden)

    C.A. Kaiser

    2011-05-01

    Full Text Available Depending on the location, dermatoses can produce blemishes that severely impair quality of life and require highly effective treatment that is otherwise used for extensive skin involvement. We report the case of a 39-year-old, otherwise healthy male disfigured by an 8 × 7-cm hypopigmented and centrally atrophic annular plaque with erythematous indurated borders in an area of scar tissue on his forehead. Skin biopsies revealed non-caseating granulomas, and hilar involvement was identified, leading to the diagnosis of systemic sarcoidosis stage II with cutaneous involvement. The lesions proved resistant to multiple therapies, but responded within 4 months to adalimumab with regression of the lesion and inflammatory infiltrate. The visual analogue scale of disease activity decreased from 7/10 to 3.5/10, and the Dermatology Life Quality Index from 16/30 to 3/30 points. In conclusion, TNF-α inhibition can control inflammation and disfigurement by cutaneous sarcoidosis and restore quality of life.

  6. Roughness Measurement of Dental Materials

    Science.gov (United States)

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

    2016-06-01

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

  7. Nonlinear shear behavior of rock joints using a linearized implementation of the Barton–Bandis model

    Directory of Open Access Journals (Sweden)

    Simon Heru Prassetyo

    2017-08-01

    Full Text Available Experiments on rock joint behaviors have shown that joint surface roughness is mobilized under shearing, inducing dilation and resulting in nonlinear joint shear strength and shear stress vs. shear displacement behaviors. The Barton–Bandis (BB joint model provides the most realistic prediction for the nonlinear shear behavior of rock joints. The BB model accounts for asperity roughness and strength through the joint roughness coefficient (JRC and joint wall compressive strength (JCS parameters. Nevertheless, many computer codes for rock engineering analysis still use the constant shear strength parameters from the linear Mohr–Coulomb (M−C model, which is only appropriate for smooth and non-dilatant joints. This limitation prevents fractured rock models from capturing the nonlinearity of joint shear behavior. To bridge the BB and the M−C models, this paper aims to provide a linearized implementation of the BB model using a tangential technique to obtain the equivalent M−C parameters that can satisfy the nonlinear shear behavior of rock joints. These equivalent parameters, namely the equivalent peak cohesion, friction angle, and dilation angle, are then converted into their mobilized forms to account for the mobilization and degradation of JRC under shearing. The conversion is done by expressing JRC in the equivalent peak parameters as functions of joint shear displacement using proposed hyperbolic and logarithmic functions at the pre- and post-peak regions of shear displacement, respectively. Likewise, the pre- and post-peak joint shear stiffnesses are derived so that a complete shear stress-shear displacement relationship can be established. Verifications of the linearized implementation of the BB model show that the shear stress-shear displacement curves, the dilation behavior, and the shear strength envelopes of rock joints are consistent with available experimental and numerical results.

  8. The limitations on applying classical thin plate theory to thin annular plates clamped on the inner boundary

    Directory of Open Access Journals (Sweden)

    Daniel W. Zietlow

    2012-12-01

    Full Text Available The experimentally measured resonance frequencies of a thin annular plate with a small ratio of inner to outer radii and clamped on the inner boundary are compared to the predictions of classical thin-plate (CTP theory and a finite-element (FE model. The results indicate that, contrary to the conclusions presented in a number of publications, CTP theory does not accurately predict the frequencies of a relatively small number of resonant modes at lower frequencies. It is shown that these inaccuracies are attributable to shear deformations, which are thought to be negligible in thin plates and are neglected in CTP theory. Of particular interest is the failure of CTP theory to accurately predict the resonance frequency of the lowest vibrational mode, which was shifted approximately 30% by shear motion at the inner boundary.

  9. First annular-ring coupled structure cavity for the Japan Proton Accelerator Research Complex linac

    Directory of Open Access Journals (Sweden)

    Hiroyuki Ao

    2012-05-01

    Full Text Available The first annular-ring coupled structure (ACS cavity for the Japan Proton Accelerator Research Complex (J-PARC linac has been developed in order to confirm and establish its fabrication processes. This cavity includes 34 accelerating cells, which is 3.4 times as many as the prototype cavity (buncher of the J-PARC ACS. The cell frequencies before brazing were tuned within the required accuracies. After brazing, the accelerating- and coupling-mode frequencies were 972.19 and 972.63 MHz on average, respectively, which were higher than the operating frequency of 972 MHz. Although the accelerating-mode frequency can be corrected to 972 MHz using adjustable plungers, these frequency errors adversely affected the on-axis electric field. This cavity was successfully conditioned up to 1.6 MW. This power corresponds to an accelerating field of 4.7  MV/m, which is 10% higher than the design value of 4.2  MV/m. In order to find the issue caused by the excited coupling cells, this cavity was also conditioned at the higher and lower frequencies that were detuned from the operating frequency of 972 MHz. Here we present the frequency tuning processes, the low-level rf measurements, and the high-power test results. We also discuss the most reasonable scenario for frequency tuning in future work.

  10. ROUGHNESS ON WOOD SURFACES AND ROUGHNESS MEASUREMENT METHODS

    Directory of Open Access Journals (Sweden)

    İsmail Aydın

    2003-04-01

    Full Text Available Some visual characteristics of wood such as color, pattern and texture determine the quality of manufactured products. Surface properties of wood material are important both in production and marketing after production. Initial studies related to the roughness of wood surface were begun in early 1950’s. However, no general agreed standardization can not have been developed for wood surfaces. Surface roughness of wood is function of the production process, product type and the natural anatomical properties of wood. Contact and non-contact tracing methods are used to measure of wood surface roughness. Surface roughness also affects the gluability and wettability of wood surfaces. The success in finishing also depends on the surface roughness of wood.

  11. Variations in roughness predictions (flume experiments)

    NARCIS (Netherlands)

    Noordam, Daniëlle; Blom, Astrid; van der Klis, H.; Hulscher, Suzanne J.M.H.; Makaske, A.; Wolfert, H.P.; van Os, A.G.

    2005-01-01

    Data of flume experiments with bed forms are used to analyze and compare different roughness predictors. In this study, the hydraulic roughness consists of grain roughness and form roughness. We predict the grain roughness by means of the size of the sediment. The form roughness is predicted by

  12. When the going gets rough - studying the effect of surface roughness on the adhesive abilities of tree frogs.

    Science.gov (United States)

    Crawford, Niall; Endlein, Thomas; Pham, Jonathan T; Riehle, Mathis; Barnes, W Jon P

    2016-01-01

    Tree frogs need to adhere to surfaces of various roughnesses in their natural habitats; these include bark, leaves and rocks. Rough surfaces can alter the effectiveness of their toe pads, due to factors such as a change of real contact area and abrasion of the pad epithelium. Here, we tested the effect of surface roughness on the attachment abilities of the tree frog Litoria caerulea. This was done by testing shear and adhesive forces on artificial surfaces with controlled roughness, both on single toe pads and whole animal scales. It was shown that frogs can stick 2-3 times better on small scale roughnesses (3-6 µm asperities), producing higher adhesive and frictional forces, but relatively poorly on the larger scale roughnesses tested (58.5-562.5 µm asperities). Our experiments suggested that, on such surfaces, the pads secrete insufficient fluid to fill the space under the pad, leaving air pockets that would significantly reduce the Laplace pressure component of capillarity. Therefore, we measured how well the adhesive toe pad would conform to spherical asperities of known sizes using interference reflection microscopy. Based on experiments where the conformation of the pad to individual asperities was examined microscopically, our calculations indicate that the pad epithelium has a low elastic modulus, making it highly deformable.

  13. When the going gets rough – studying the effect of surface roughness on the adhesive abilities of tree frogs

    Directory of Open Access Journals (Sweden)

    Niall Crawford

    2016-12-01

    Full Text Available Tree frogs need to adhere to surfaces of various roughnesses in their natural habitats; these include bark, leaves and rocks. Rough surfaces can alter the effectiveness of their toe pads, due to factors such as a change of real contact area and abrasion of the pad epithelium. Here, we tested the effect of surface roughness on the attachment abilities of the tree frog Litoria caerulea. This was done by testing shear and adhesive forces on artificial surfaces with controlled roughness, both on single toe pads and whole animal scales. It was shown that frogs can stick 2–3 times better on small scale roughnesses (3–6 µm asperities, producing higher adhesive and frictional forces, but relatively poorly on the larger scale roughnesses tested (58.5–562.5 µm asperities. Our experiments suggested that, on such surfaces, the pads secrete insufficient fluid to fill the space under the pad, leaving air pockets that would significantly reduce the Laplace pressure component of capillarity. Therefore, we measured how well the adhesive toe pad would conform to spherical asperities of known sizes using interference reflection microscopy. Based on experiments where the conformation of the pad to individual asperities was examined microscopically, our calculations indicate that the pad epithelium has a low elastic modulus, making it highly deformable.

  14. Stick–slip friction of gecko-mimetic flaps on smooth and rough surfaces

    Science.gov (United States)

    Das, Saurabh; Cadirov, Nicholas; Chary, Sathya; Kaufman, Yair; Hogan, Jack; Turner, Kimberly L.; Israelachvili, Jacob N.

    2015-01-01

    The discovery and understanding of gecko ‘frictional-adhesion’ adhering and climbing mechanism has allowed researchers to mimic and create gecko-inspired adhesives. A few experimental and theoretical approaches have been taken to understand the effect of surface roughness on synthetic adhesive performance, and the implications of stick–slip friction during shearing. This work extends previous studies by using a modified surface forces apparatus to quantitatively measure and model frictional forces between arrays of polydimethylsiloxane gecko footpad-mimetic tilted microflaps against smooth and rough glass surfaces. Constant attachments and detachments occur between the surfaces during shearing, as described by an avalanche model. These detachments ultimately result in failure of the adhesion interface and have been characterized in this study. Stick–slip friction disappears with increasing velocity when the flaps are sheared against a smooth silica surface; however, stick–slip was always present at all velocities and loads tested when shearing the flaps against rough glass surfaces. These results demonstrate the significance of pre-load, shearing velocity, shearing distances, commensurability and shearing direction of gecko-mimetic adhesives and provide us a simple model for analysing and/or designing such systems. PMID:25589569

  15. Stick-slip friction of gecko-mimetic flaps on smooth and rough surfaces.

    Science.gov (United States)

    Das, Saurabh; Cadirov, Nicholas; Chary, Sathya; Kaufman, Yair; Hogan, Jack; Turner, Kimberly L; Israelachvili, Jacob N

    2015-03-06

    The discovery and understanding of gecko 'frictional-adhesion' adhering and climbing mechanism has allowed researchers to mimic and create gecko-inspired adhesives. A few experimental and theoretical approaches have been taken to understand the effect of surface roughness on synthetic adhesive performance, and the implications of stick-slip friction during shearing. This work extends previous studies by using a modified surface forces apparatus to quantitatively measure and model frictional forces between arrays of polydimethylsiloxane gecko footpad-mimetic tilted microflaps against smooth and rough glass surfaces. Constant attachments and detachments occur between the surfaces during shearing, as described by an avalanche model. These detachments ultimately result in failure of the adhesion interface and have been characterized in this study. Stick-slip friction disappears with increasing velocity when the flaps are sheared against a smooth silica surface; however, stick-slip was always present at all velocities and loads tested when shearing the flaps against rough glass surfaces. These results demonstrate the significance of pre-load, shearing velocity, shearing distances, commensurability and shearing direction of gecko-mimetic adhesives and provide us a simple model for analysing and/or designing such systems. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  16. Modeling interface shear behavior of granular materials using micro-polar continuum approach

    Science.gov (United States)

    Ebrahimian, Babak; Noorzad, Ali; Alsaleh, Mustafa I.

    2017-08-01

    Recently, the authors have focused on the shear behavior of interface between granular soil body and very rough surface of moving bounding structure. For this purpose, they have used finite element method and a micro-polar elasto-plastic continuum model. They have shown that the boundary conditions assumed along the interface have strong influences on the soil behavior. While in the previous studies, only very rough bounding interfaces have been taken into account, the present investigation focuses on the rough, medium rough and relatively smooth interfaces. In this regard, plane monotonic shearing of an infinite extended narrow granular soil layer is simulated under constant vertical pressure and free dilatancy. The soil layer is located between two parallel rigid boundaries of different surface roughness values. Particular attention is paid to the effect of surface roughness of top and bottom boundaries on the shear behavior of granular soil layer. It is shown that the interaction between roughness of bounding structure surface and the rotation resistance of bounding grains can be modeled in a reasonable manner through considered Cosserat boundary conditions. The influence of surface roughness is investigated on the soil shear strength mobilized along the interface as well as on the location and evolution of shear localization formed within the layer. The obtained numerical results have been qualitatively compared with experimental observations as well as DEM simulations, and acceptable agreement is shown.

  17. Rotordynamic Analysis of Textured Annular Seals With Multiphase (Bubbly Flow

    Directory of Open Access Journals (Sweden)

    Gérard PINEAU

    2011-09-01

    Full Text Available For some applications it must be considered that the flow in the annular seal contains a mixture of liquid and gas. The multiphase character of the flow is described by the volume fraction of gas (usually air contained in the liquid under the form of bubbles.The fluid is then a homogenous mixture of air and liquid all thru the annular seal. Its local gas volume fraction depends on the pressure field and is calculated by using a simplified form of the Rayleigh-Plesset equation.The influence of such of a multiphase (bubbly flow on the dynamic characteristics of a straight annular seal is minimal because the volume of the fluid is reduced.The situation is quite different for textured annular (damper seals provided with equally spaced deep cavities intended to increase the damping capabilities and to reduce the leakage flow rate.As a by-product, the volume of the fluid in the seal increases drastically and the compressibility effects stemming from the bubbly nature of the flow are largely increased even for a low gas volume fraction. The present work depicts the influence of the gas volume fraction on the dynamic characteristics of a textured annular seal. It is shown that variations of the gas volume fraction between 1% and 0.1% can lead to frequency dependent stiffness, damping and added mass coefficients.

  18. Far-field Diffraction Properties of Annular Walsh Filters

    Directory of Open Access Journals (Sweden)

    Pubali Mukherjee

    2013-01-01

    Full Text Available Annular Walsh filters are derived from the rotationally symmetric annular Walsh functions which form a complete set of orthogonal functions that take on values either +1 or −1 over the domain specified by the inner and outer radii of the annulus. The value of any annular Walsh function is taken as zero from the centre of the circular aperture to the inner radius of the annulus. The three values 0, +1, and −1 in an annular Walsh function can be realized in a corresponding annular Walsh filter by using transmission values of zero amplitude (i.e., an obscuration, unity amplitude and zero phase, and unity amplitude and phase, respectively. Not only the order of the Walsh filter but also the size of the inner radius of the annulus provides an additional degree of freedom in tailoring of point spread function by using these filters for pupil plane filtering in imaging systems. In this report, we present the far-field amplitude characteristics of some of these filters to underscore their potential for effective use in several demanding applications like high-resolution microscopy, optical data storage, microlithography, optical encryption, and optical micromanipulation.

  19. Reduced shear power spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Dodelson, Scott; /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Northwestern U.; Shapiro, Charles; /Chicago U. /KICP, Chicago; White, Martin J.; /UC, Berkeley, Astron.

    2005-08-01

    Measurements of ellipticities of background galaxies are sensitive to the reduced shear, the cosmic shear divided by (1-{kappa}) where {kappa} is the projected density field. They compute the difference between shear and reduced shear both analytically and with simulations. The difference becomes more important an smaller scales, and will impact cosmological parameter estimation from upcoming experiments. A simple recipe is presented to carry out the required correction.

  20. Dynamic property changes in stapedial annular ligament associated with acute otitis media in the chinchilla.

    Science.gov (United States)

    Hitt, Brooke M; Wang, Xuelin; Gan, Rong Z

    2017-02-01

    Located at the end of the ossicular chain, the stapedial annular ligament (SAL) serves as a closed yet mobile boundary between the cochlear fluid and stapes footplate. It is unclear how SAL properties change with acute otitis media (AOM). This paper reports the measurements of SAL dynamic properties in chinchilla AOM model using dynamic mechanical analyzer (DMA) and frequency-temperature superposition (FTS) principle. AOM was analyzed in two infection groups: 4 days (4D) and 8 days (8D) post induction. SAL specimens were measured using DMA at three temperatures: 5, 25, and 37°C. To extend the testing frequencies to higher levels, FTS principle was employed. Then generalized Maxwell model was utilized to define the constitutive equations of the SAL. The complex shear moduli were obtained from seven samples of control, 4D, and 8D groups. Results show that the storage and loss shear moduli of SALs decreased due to AOM. The storage moduli for 4D and 8D ears were similar below 100Hz, and the loss modulus for 4D was significantly larger than 8D across the entire frequency range. This study reports data that contributes to ear biomechanics and improves understanding on the effects of AOM in middle ear tissues. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

  1. Vibration Analysis of Annular Sector Plates under Different Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Dongyan Shi

    2014-01-01

    Full Text Available An analytical framework is developed for the vibration analysis of annular sector plates with general elastic restraints along each edge of plates. Regardless of boundary conditions, the displacement solution is invariably expressed as a new form of trigonometric expansion with accelerated convergence. The expansion coefficients are treated as the generalized coordinates and determined using the Rayleigh-Ritz technique. This work allows a capability of modeling annular sector plates under a variety of boundary conditions and changing the boundary conditions as easily as modifying the material properties or dimensions of the plates. Of equal importance, the proposed approach is universally applicable to annular sector plates of any inclusion angles up to 2π. The reliability and accuracy of the current method are adequately validated through numerical examples.

  2. The Annular Gap: Gamma-Ray & Radio Emission of Pulsars

    Science.gov (United States)

    Qiao, G. J.; Du, Y. J.; Han, J. L.; Xu, R. X.

    2013-01-01

    Pulsars have been found more than 40 years. Observations from radio to gamma-rays present abundant information. However, the radiation mechanism is still an open question. It is found that the annular gap could be formed in the magnetosphere of pulsars (neutron stars or quark stars), which combines the advantages of the polar cap, slot gap and outer gap models. It is emphasized that observations of some radio pulsars, normal and millisecond gamma-ray pulsars (MSGPs) show that the annular gap would play a very important role. Here we show some observational and theoretical evidences about the annular gap. For example, bi-drifting sub-pulses; radio and gamma-ray millisecond pulsars and so on.

  3. Comparative histology of the annular and cruciform pulleys.

    Science.gov (United States)

    Katzman, B M; Klein, D M; Garven, T C; Caligiuri, D A; Kung, J

    1999-06-01

    Twenty annular and 12 cruciform pulleys were dissected from four unembalmed fresh cadaveric fingers and stained with haematoxylin and eosin, Verhoeff-van Gieson stain for elastin, alcian blue stain for hyaluronic acid, and a separate stain for S-100 to identify chondroid cells. Three distinct layers were identified in both annular and cruciform pulleys: an outer layer of fibrofatty tissue with vascular channels outermost, an inner layer of hyaluronic acid-secreting cells, and a collagen-rich layer in between. Chondroid metaplasia was noted in the inner layer of both types of pulleys. Minimal differences were noted in regard to the elastin fibre content of the pulleys, with slightly more elastin in the annular pulleys, but no other differences were noted.

  4. Effects of shear coupling on shear properties of wood

    Science.gov (United States)

    Jen Y. Liu

    2000-01-01

    Under pure shear loading, an off-axis element of orthotropic material such as pure wood undergoes both shear and normal deformations. The ratio of the shear strain to a normal strain is defined as the shear coupling coefficient associated with the direction of the normal strain. The effects of shear coupling on shear properties of wood as predicted by the orthotropic...

  5. Desmitis of the fetlock annular ligament in the horse.

    Science.gov (United States)

    Verschooten, F; Picavet, T M

    1986-03-01

    Desmitis of the fetlock annular ligament was diagnosed in 30 horses during a period of eight years. Most of the horses had been lame for a prolonged period and had chronically distended digital flexor tendon sheaths. Air tendograms demonstrated thickened palmar or plantar annular ligaments. In 25 horses the ligament was cut longitudinally; of these, 16 horses returned to full work without any difficulty and one became sound after a second operation. Follow up time varied from three months to seven-and-a-half years. None of the five untreated horses returned to work.

  6. Simple Model For Pressure Drop In Horizontal Core Annular Flow

    OpenAIRE

    Bannwart A.C.

    1999-01-01

    Based upon experimental data for heavy oil-water flow inside steel (26.7 mm ID) and cemented (23.9 mm ID) horizontal tubes, a very simple model for pressure drop in the core annular flow pattern was developed. The experiments were run at room temperature and the fluids used were a fuel oil (μ = 2.7 Pa.s, ρ = 989 kg/m3) and tap water, both drawn from a separator tank. First, it is shown that for both tubes the so-called 'perfect core annular flow' approach (shortly PCAF) poorly correlates the ...

  7. Mitral-aortic annular enlargement: modification of Manouguian's technique

    Directory of Open Access Journals (Sweden)

    Costa Mario Gesteira

    2002-01-01

    Full Text Available We hereby present a technical modification for mitral-aortic annular enlargement. The mitral valve is replaced through the retro-septal approach, avoiding patches for left atrial roof closure. We report a mitral-aortic valve replacement in a patient whose original annuli would preclude adequate prostheses. The simultaneous annular enlargement may be necessary for avoiding patient-prosthesis mismatch and for reconstructing destroyed mitral and aortic annuli. The technique may minimize the risk of bleeding and of paravalvular leakage, using an approach well known to cardiac surgeons.

  8. Patch Type Granuloma Annulare Imitating Cutaneous T-Cell Lymphoma

    Directory of Open Access Journals (Sweden)

    Seval Doğruk Kaçar

    2015-03-01

    Full Text Available Granuloma annulare (GA is a benign inflammatory skin disease with distinct clinical and histopathological findings. Patch type GA is described with erythematous patches beyond the classical clinical appearance and an interstitial pattern is observed without histopathologically granulomas with disseminated histiocytes among collagen bundles and vessels. Here we report 46 year old woman diagnosed as patch type GA after a punch biopsy performed from the annular bordered patches in belly area, which is a classical area for mycosis fungoides (MF evolution, and lesions increasingly spreading out within a 2 year period.

  9. Interval-Valued Neutrosophic Soft Rough Sets

    Directory of Open Access Journals (Sweden)

    Said Broumi

    2015-01-01

    Full Text Available We first defined interval-valued neutrosophic soft rough sets (IVN-soft rough sets for short which combine interval-valued neutrosophic soft set and rough sets and studied some of its basic properties. This concept is an extension of interval-valued intuitionistic fuzzy soft rough sets (IVIF-soft rough sets.

  10. Multi-functional annular fairing for coupling launch abort motor to space vehicle

    Science.gov (United States)

    Camarda, Charles J. (Inventor); Scotti, Stephen J. (Inventor); Buning, Pieter G. (Inventor); Bauer, Steven X. S. (Inventor); Engelund, Walter C. (Inventor); Schuster, David M. (Inventor)

    2011-01-01

    An annular fairing having aerodynamic, thermal, structural and acoustic attributes couples a launch abort motor to a space vehicle having a payload of concern mounted on top of a rocket propulsion system. A first end of the annular fairing is fixedly attached to the launch abort motor while a second end of the annular fairing is attached in a releasable fashion to an aft region of the payload. The annular fairing increases in diameter between its first and second ends.

  11. Simulation of shear and turbulence impact on wind turbine performance

    DEFF Research Database (Denmark)

    Wagner, Rozenn; Courtney, Michael; Larsen, Torben J.

    Aerodynamic simulations (HAWC2Aero) were used to investigate the influence of the speed shear, the direction shear and the turbulence intensity on the power output of a multi-megawatt turbine. First simulation cases with laminar flow and power law wind speed profiles were compared to the case...... of a uniform inflow. Secondly, a similar analysis was done for cases with direction shear. In each case, we derived a standard power curve (function of the wind speed at hub height) and power curves obtained with various definitions of equivalent wind speed in order to reduce the scatter due to shear. Thirdly......, the variations of the power output and the power curve were analysed for various turbulence intensities. Furthermore, the equivalent speed method was successfully tested on a power curve resulting from simulations cases combining shear and turbulence. Finally, we roughly simulated the wind speed measurements we...

  12. Fuzzy-Rough Cognitive Networks.

    Science.gov (United States)

    Nápoles, Gonzalo; Mosquera, Carlos; Falcon, Rafael; Grau, Isel; Bello, Rafael; Vanhoof, Koen

    2018-01-01

    Rough Cognitive Networks (RCNs) are a kind of granular neural network that augments the reasoning rule present in Fuzzy Cognitive Maps with crisp information granules coming from Rough Set Theory. While RCNs have shown promise in solving different classification problems, this model is still very sensitive to the similarity threshold upon which the rough information granules are built. In this paper, we cast the RCN model within the framework of fuzzy rough sets in an attempt to eliminate the need for a user-specified similarity threshold while retaining the model's discriminatory power. As far as we know, this is the first study that brings fuzzy sets into the domain of rough cognitive mapping. Numerical results in the presence of 140 well-known pattern classification problems reveal that our approach, referred to as Fuzzy-Rough Cognitive Networks, is capable of outperforming most traditional classifiers used for benchmarking purposes. Furthermore, we explore the impact of using different heterogeneous distance functions and fuzzy operators over the performance of our granular neural network. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Aseptic tenosynovitis of the digital flexor tendon sheath, fetlock and pastern annular ligament constriction.

    Science.gov (United States)

    Dik, K J; Dyson, S J; Vail, T B

    1995-08-01

    The anatomy of the digital flexor tendon sheath and related tendons and ligaments is described. Diagnosis and management of acute tenosynovitis and long-term tenosynovitis and associated tendon injuries are discussed, as well as the syndrome of stenosis of the fetlock canal (or fetlock annular ligament constriction) and palmar annular ligament constriction. Desmitis of the palmar annular ligament is also described.

  14. Generalized granuloma annulare as an initial manifestation of chronic myelomonocytic leukemia: a report of 2 cases.

    Science.gov (United States)

    Hinckley, Michael R; Walsh, Sarah N; Molnár, István; Sheehan, Daniel J; Sangueza, Omar P; Yosipovitch, Gil

    2008-06-01

    Granuloma annulare is a dermatologic condition of unknown etiology that has been associated with systemic diseases and reported to be a paraneoplastic manifestation. Two patients with generalized granuloma annulare as an initial manifestation of chronic myelomonocytic leukemia are herein described. We suggest that chronic myelomonocytic leukemia should be added to the list of systemic diseases associated with generalized granuloma annulare.

  15. Boundary Shear Stress Along Vegetated Streambanks

    Science.gov (United States)

    Clark, L. A.; Wynn, T.

    2007-12-01

    Sediment, a leading cause of water quality impairment, damages aquatic ecosystems and interferes with recreational uses and water treatment processes. Streambank retreat can contribute as much as 85% of watershed sediment yield. Vegetation is an important component of stream restoration designs used to control streambank retreat, but vegetation effects on streambank boundary shear stress (SBSS) need to be quantified. The overall goal of this experiment is to predict boundary shear stress along vegetated streambanks. This goal will be met by determining a method for measuring boundary shear stress in the field along hydraulically rough streambanks, evaluating the effects of streambank vegetation on boundary shear stress in the field, and developing predictive methods based on measurable vegetative properties. First, three streambank vegetation types (herbaceous, shrubbery, and woody) will be modeled in a flume study to examine both boundary shear stress measurement theory and instruments for field use. An appropriate method (law of the wall, Reynold's stresses, TKE, or average wall shear stress) and field instrument (ADV, propeller, or Pitot tube) will be selected, resulting in a field technique to measure SBSS. Predictive methods for estimating SBSS, based on common vegetation measurements, will be developed in the flume study and validated with field data. This research is intended to improve our understanding of the role of riparian vegetation in stream morphology by evaluating the effects of vegetation on boundary shear stress, providing insight to the type and density of vegetation required for streambank stability. The results will also aide in quantifying sediment inputs from streambanks, providing quantitative information for stream restoration projects and watershed management planning.

  16. Shear heating by translational brittle reverse faulting along a single ...

    Indian Academy of Sciences (India)

    Increase in temperature (Ti) of faulted hangingwall and footwall blocks by frictional/shear heating for planar rough reverse faults is proportional to the coefficient of friction (μ), density and thickness of the hangingwall block (ρ). Ti increases as movement progresses with time. Thermal conductivity (Ki) and thermal diffusivity ...

  17. Palmar annular ligament desmotomy in horses with the Arthrex ...

    African Journals Online (AJOL)

    Ibrahim Eldaghayes

    2018-01-25

    Jan 25, 2018 ... Published: 07/02/2018. Palmar annular ligament desmotomy in horses with the Arthrex-Centerline™ ... Ten horse distal front limbs from horses free of PAL disease were prepared for tenoscopy of the digital flexor tendon sheath .... operative field, a better diagnosis and a reduction in both the surgical wound.

  18. Squeeze Film Behaviour in Rotating Porous Annular Discs ...

    African Journals Online (AJOL)

    The squeeze film behaviour between rotating annular discs, when the upper disc with a porous facing approached the parallel lower disc, was theoretically analysed. The lubricant was a magnetic fluid and the external magnetic field was oblique to the lower disc. Expressions were obtained for pressure, load capacity and ...

  19. Magnetic fluid based squeeze film between porous annular curved ...

    Indian Academy of Sciences (India)

    Ghatlodia, Ahmedabad 380 061, India. MS received 7 March 2000; revised 7 June 2001. Abstract. The squeeze film behaviour between rotating annular plates was analysed theoretically when the curved upper plate with a uniform porous facing approached the impermeable and flat lower plate, considering a magnetic fluid ...

  20. Ultrasonographic evaluation of fetlock annular ligament constriction in the horse.

    Science.gov (United States)

    Dik, K J; van den Belt, A J; Keg, P R

    1991-07-01

    The diagnosis of restriction of free movement of the flexor tendons through the fetlock canal usually rests on the characteristic clinical appearance of this condition, or airtendography. In a series of seven normal Warmblood horses and 16 diseased horses of various breeds, the efficacy of ultrasonography in the diagnosis of this condition was determined. In normal limbs, the annular ligament is a very thin structure usually not visible on sonograms. In diseased limbs, ultrasonography outlined flexor tendon injury, distension and thickening of the digital sheath, peritendovaginal tissue proliferation and thickening of the annular ligament. Four different types of constriction syndrome were noticed. The first type (nine cases), was characterised by thickening of the annular ligament and distension of the digital sheath; the second type (three cases) was dominated by distension of the digital sheath; the third type (three cases) was characterised by superficial digital flexor tendon injury and thickening of the annular ligament and in the fourth type (one case), the constriction resulted from distension of the digital sheath and extensive peritendovaginal tissue proliferation.

  1. Free asymmetric transverse vibration of polar orthotropic annular ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. In the present paper, free asymmetric transverse vibrations of a non- uniform polar orthotropic annular sector plate, with parabolically varying thickness in the radial direction, have been studied on the basis of classical plate theory. The circular edges of the plate are elastically restrained against translation and.

  2. Squeeze Film Behaviour in Rotating Porous Annular Discs ...

    African Journals Online (AJOL)

    Squeeze Film Behaviour in Rotating Porous Annular Discs Lubricated with Magnetic Fluid. ... Our aim was to study the effects of magnetization and rotation of the discs on dimensionless pressure, load capacity and response time whose computed values were displayed in tabular and graphical forms. In all cases, pressure, ...

  3. RESIDENCE TIME DISTRIBUTION OF FLUIDS IN STIRRED ANNULAR PHOTOREACTORS

    Science.gov (United States)

    When gases flow through an annular photoreactor at constant rate, some of the gas spends more or less than the average residence time in the reactor. This spread of residence time can have an important effect on the performance of the reactor. this study tested how the residence...

  4. Quench-induced trapping of magnetic flux in annular

    DEFF Research Database (Denmark)

    Aaroe, M.; Monaco, R.; Rivers, R.

    2008-01-01

    The aim of the project is to investigate spontaneous symmetry breaking in non-adiabatic phase transitions (Kibble-Zurek processes). A long and narrow annular Josephson tunnel junction is subjected to repeated thermal quenches through the normal-superconducting transition. The quench rate is varied...

  5. Effect of annular secondary conductor in a linear electromagnetic ...

    Indian Academy of Sciences (India)

    This paper presents the variation of average axial force density in the annular secondary conductor of a linear electromagnetic stirrer. ... Department of Electrical Engineering, Indian Institute of Technology, Bombay, Powai, Mumbai 400 076; Power Electronics Group, Department of Electrical Engineering, Indian Institute of ...

  6. Magnetosphere Structure and the Annular Gap Model of Pulsars

    Science.gov (United States)

    Qiao, G. J.; Lee, K. J.; Wang, H. G.; Xu, R. X.

    Pulsar radio and γ-ray emission has been studied for about forty years, yet no elaborated model is present to account for all the emission of pulsars from radio to γ-ray bands. A reasonable emission model should present the mechanism for wide band radiation. The magnetosphere structure and particle acceleration regions are the basis for solving problem, observations are important inputs to establish a reasonable model. In our work, both radio and gamma-ray observations have been considered. We will show how they can limit the radiation locations and radiation mechanisms. The advantages and disadvantages for different radiation locations (such as the polar gap, the outer gap and the annular gap) are discussed in comparison with observational facts. The annular gap model, an joint model for both radio and γ-ray emissions, was proposed recently and reproduce successfully some important observational phenomenon, e.g., bi-drifting. We will also discuss for radio and γ-ray observations of PSR B1055-52, and show that radiations come from the annular region and the core region. Success in reproducing many observational facts suggest that the annular gap is a promising model for pulsar multi-wavelength radiation.

  7. Localized granuloma annulare and autoimmune thyroiditis in a ...

    African Journals Online (AJOL)

    The association of granuloma annulare (GA) and autoimmune thyroiditis has been documented in the literature in 13 previous cases. However, the pathogenesis of GA remains obscure. Possible pathogenetic factors suggested include: humoral and delayed type hypersensitivity, vascular damage, metabolic disorder, or, ...

  8. Adjoint Optimisation of the Turbulent Flow in an Annular Diffuser

    DEFF Research Database (Denmark)

    Gotfredsen, Erik; Agular Knudsen, Christian; Kunoy, Jens Dahl

    2017-01-01

    In the present study, a numerical optimisation of guide vanes in an annular diffuser, is performed. The optimisation is preformed for the purpose of improving the following two parameters simultaneously; the first parameter is the uniformity perpen-dicular to the flow direction, a 1/3 diameter...

  9. Density changes in shear bands of a metallic glass determined by correlative analytical transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rösner, Harald, E-mail: rosner@uni-muenster.de [Institut für Materialphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, D-48149 Münster (Germany); Peterlechner, Martin [Institut für Materialphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, D-48149 Münster (Germany); Kübel, Christian [Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology (INT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen (Germany); Schmidt, Vitalij [Institut für Materialphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, D-48149 Münster (Germany); Wilde, Gerhard [Institut für Materialphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, D-48149 Münster (Germany); Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China)

    2014-07-01

    Density changes between sheared zones and their surrounding amorphous matrix as a result of plastic deformation in a cold-rolled metallic glass (melt-spun Al{sub 88}Y{sub 7}Fe{sub 5}) were determined using high-angle annular dark-field (HAADF) detector intensities supplemented by electron-energy loss spectroscopy (EELS), energy-dispersive X-ray (EDX) and nano-beam diffraction analyses. Sheared zones or shear bands were observed as regions of bright or dark contrast arising from a higher or lower density relative to the matrix. Moreover, abrupt contrast changes from bright to dark and vice versa were found within individual shear bands. We associate the decrease in density mainly with an enhanced free volume in the shear bands and the increase in density with concomitant changes of the mass. This interpretation is further supported by changes in the zero loss and Plasmon signal originating from such sites. The limits of this new approach are discussed. - Highlights: • We describe a novel approach for measuring densities in shear bands of metallic glasses. • The linear relation of the dark-field intensity I/I{sub 0} and the mass thickness ρt was used. • Individual shear bands showed abrupt contrast changes from bright to dark and vice versa. • Density changes ranging from about −10% to +6% were found for such shear bands. • Mixtures of amorphous/medium range ordered domains were found within the shear bands.

  10. Shear Thinning in Xenon

    Science.gov (United States)

    Bergm Robert F.; Moldover, Michael R.; Yao, Minwu; Zimmerli, Gregory A.

    2009-01-01

    We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids such as molten plastics or ketchup, near the critical point of xenon. The data span a wide range of dimensionless shear rate: the product of the shear rate and the relaxation time of critical fluctuations was greater than 0.001 and was less than 700. As predicted by theory, shear thinning occurred when this product was greater than 1. The measurements were conducted aboard the Space Shuttle Columbia to avoid the density stratification caused by Earth's gravity.

  11. Stochastic control with rough paths

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Joscha [University of California San Diego (United States); Friz, Peter K., E-mail: friz@math.tu-berlin.de [TU & WIAS Berlin (Germany); Gassiat, Paul [CEREMADE, Université Paris-Dauphine, PSL Research University (France)

    2017-04-15

    We study a class of controlled differential equations driven by rough paths (or rough path realizations of Brownian motion) in the sense of Lyons. It is shown that the value function satisfies a HJB type equation; we also establish a form of the Pontryagin maximum principle. Deterministic problems of this type arise in the duality theory for controlled diffusion processes and typically involve anticipating stochastic analysis. We make the link to old work of Davis and Burstein (Stoch Stoch Rep 40:203–256, 1992) and then prove a continuous-time generalization of Roger’s duality formula [SIAM J Control Optim 46:1116–1132, 2007]. The generic case of controlled volatility is seen to give trivial duality bounds, and explains the focus in Burstein–Davis’ (and this) work on controlled drift. Our study of controlled rough differential equations also relates to work of Mazliak and Nourdin (Stoch Dyn 08:23, 2008).

  12. Self-focusing effect of annular beams propagating in the atmosphere.

    Science.gov (United States)

    Zhang, Yuqiu; Ji, Xiaoling; Li, Xiaoqing; Li, Qiang; Yu, Hong

    2017-09-04

    The self-focusing effect of annular beams propagating in the atmosphere to assist delivering powerful laser beams from orbit to the ground is studied in detail. It is found the annular beam is compressed more strongly due to the self-focusing effect as the beam obscure ratio increases. On the other hand, the self-focusing effect between annular, flat-topped and Gaussian beams is compared. It is shown that the self-focusing effect on the annular beam is stronger than that on flat-topped and Gaussian beams. However, the threshold critical power values of annular, flat-topped and Gaussian beams should be in sequence from small to large. Furthermore, the expression of the B integral of annular beams propagating from orbit to the ground in the atmosphere is derived, and the fitting equation related to the B integral of annular beams for maximal compression without filamentation is presented.

  13. LAMINAR FLOW THROUGH A TUBE WITH AN EASILY PENETRABLE ROUGHNESS NEAR AXIS

    Directory of Open Access Journals (Sweden)

    Є.О. Гаєв

    2012-12-01

    Full Text Available  Mathematical model has been suggested and investigation carried out of laminar flow through a round tube with a porous insertion (easily penetrable roughness, EPR in its middle along the axis. Velocity and shear fields have been found analytically for stable flow region, as well as hydraulic resistance as functions of EPR density and its height.

  14. Hydrodynamic repulsion of spheroidal microparticles from micro-rough surfaces.

    Science.gov (United States)

    Belyaev, Aleksey V

    2017-01-01

    Isolation of microparticles and biological cells from mixtures and suspensions is a central problem in a variety of biomedical applications. This problem, for instance, is of an immense importance for microfluidic devices manipulating with whole blood samples. It is instructive to know how the mobility and dynamics of rigid microparticles is altered by the presence of micrometer-size roughness on walls. The presented theoretical study addresses this issue via computer simulations. The approach is based on a combination of the Lattice Boltzmann method for calculating hydrodynamics and the Lagrangian Particle dynamics method to describe the dynamics of cell membranes. The effect of the roughness on the mobility of spheroidal microparticles in a shear fluid flow was quantified. We conclude that mechanical and hydrodynamic interactions lift the particles from the surface and change their mobility. The effect is sensitive to the shape of particles.

  15. Development of empirical correlation of peak friction angle with surface roughness of discontinuities using tilt test

    Science.gov (United States)

    Serasa, Ailie Sofyiana; Lai, Goh Thian; Rafek, Abdul Ghani; Simon, Norbert; Hussein, Azimah; Ern, Lee Khai; Surip, Noraini; Mohamed, Tuan Rusli

    2016-11-01

    The significant influence of surface roughness of discontinuity surfaces is a quantity that is fundamental to the understanding of shear strength of geological discontinuities. This is due to reason that the shear strength of geological discontinuities greatly influenced the mechanical behavior of a rock mass especially in stability evaluation of tunnel, foundation, and natural slopes. In evaluating the stability of these structures, the study of peak friction angle (Φpeak) of rough discontinuity surfaces has become more prominent seeing that the shear strength is a pivotal factor causing failures. The measurement of peak friction angle however, requires an extensive series of laboratory tests which are both time and cost demanding. With that in mind, this publication presents an approach in the form of an experimentally determined polynomial equation to estimate peak friction angle of limestone discontinuity surfaces by measuring the Joint Roughness Coefficient (JRC) values from tilt tests, and applying the fore mentioned empirical correlation. A total of 1967 tilt tests and JRC measurements were conducted in the laboratory to determine the peak friction angles of rough limestone discontinuity surfaces. A polynomial equation of ɸpeak = -0.0635JRC2 + 3.95JRC + 25.2 that exhibited 0.99 coefficient of determination (R2) were obtained from the correlation of JRC and peak friction angles. The proposed correlation offers a practical method for estimation of peak friction angles of rough discontinuity surfaces of limestone from measurement of JRC in the field.

  16. A self-standing two-fluid CFD model for vertical upward two-phase annular flow

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y., E-mail: yang_liu@mail.dlut.edu.c [Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, Liaoning Province (China); Li, W.Z.; Quan, S.L. [Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, Liaoning Province (China)

    2011-05-15

    Research highlights: A mathematic model for two-phase annular flow is established in this paper. Pressure loss and wall shear stress increase with inlet gas and liquid flow velocities. Droplet mass fraction distribution exhibits a concave profile radially. - Abstract: In this paper, a new two-fluid CFD (computational fluid dynamics) model is proposed to simulate the vertical upward two-phase annular flow. This model solves the basic mass and momentum equations for the gas core region flow and the liquid film flow, where the basic governing equations are accounted for by the commercial CFD package Fluent6.3.26. The liquid droplet flow and the interfacial inter-phase effects are accounted for by the programmable interface of Fluent, UDF (user defined function). Unlike previous models, the present model includes the effect of liquid roll waves directly determined from the CFD code. It is able to provide more detailed and, the most important, self-standing information for both the gas core flow and the film flow as well as the inner tube wall situations.

  17. Direct simulation of open-channel flow in the fully rough regime: focus on fluid-roughness interaction

    Science.gov (United States)

    Mazzuoli, Marco; Uhlmann, Markus

    2015-04-01

    The interaction between an incompressible open-channel flow at Reb = 6900 and rigid spheres of size k+ = 120 mounted in square arrangement on the bottom, has been investigated by means of Direct Numerical Simulation (DNS) for the purpose of contributing to the knowledge of the basic mechanism of sediment transport. The shift generated by the roughness on mean velocity profile in the log-region is in the range of values characterizing the Fully-Rough Regime (FRR). First, average quantities (i.e. flow velocity, shear-stress distribution on the sphere surface, force and torque acting on the spheres) are analyzed exploiting the spatial periodicity of the arrangement of roughness elements. Then, spatial and temporal fluctuations of the quantities are studied. Results are compared with those obtained for a similar DNS at Reb = 2900, which is in the Transitionally-Rough Regime (TRR). Although the largest fluctuations of the velocity components are observed ~ 8 wall units below the crest of the spheres in the FRR, their effect on the drag and lift fluctuations acting on individual spheres is weaker than in the TRR. Nonetheless, the lift coefficient in the FRR case was found the 24% larger than in the TRR case. The characteristics of vortex structures in the vicinity of roughness elements are also investigated. Differences in the flow structure between the two simulations in the TRR and in the FRR reflect on the stress distribution on the surface of the spheres. Finally, the arrangement of the roughness elements might play a key role in the modulation of turbulence.

  18. Plant Communities of Rough Rock.

    Science.gov (United States)

    Jacobs, Linda

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

  19. Calibration of surface roughness standards

    DEFF Research Database (Denmark)

    Thalmann, R.; Nicolet, A.; Meli, F.

    2016-01-01

    The key comparison EURAMET.L-K8.2013 on roughness was carried out in the framework of a EURAMET project starting in 2013 and ending in 2015. It involved the participation of 17 National Metrology Institutes from Europe, Asia, South America and Africa representing four regional metrology organisat...

  20. Rough-to-smooth transition of an equilibrium neutral constant stress layer

    Science.gov (United States)

    Logan, E., Jr.; Fichtl, G. H.

    1975-01-01

    Purpose of research on rough-to-smooth transition of an equilibrium neutral constant stress layer is to develop a model for low-level atmospheric flow over terrains of abruptly changing roughness, such as those occurring near the windward end of a landing strip, and to use the model to derive functions which define the extent of the region affected by the roughness change and allow adequate prediction of wind and shear stress profiles at all points within the region. A model consisting of two bounding logarithmic layers and an intermediate velocity defect layer is assumed, and dimensionless velocity and stress distribution functions which meet all boundary and matching conditions are hypothesized. The functions are used in an asymptotic form of the equation of motion to derive a relation which governs the growth of the internal boundary layer. The growth relation is used to predict variation of surface shear stress.

  1. Human roughness perception and possible factors effecting roughness sensation.

    Science.gov (United States)

    Aktar, Tugba; Chen, Jianshe; Ettelaie, Rammile; Holmes, Melvin; Henson, Brian

    2017-06-01

    Surface texture sensation is significant for business success, in particular for solid surfaces for most of the materials; including foods. Mechanisms of roughness perception are still unknown, especially under different conditions such as lubricants with varying viscosities, different temperatures, or under different force loads during the observation of the surface. This work aims to determine the effect of those unknown factors, with applied sensory tests on 62 healthy participants. Roughness sensation of fingertip was tested under different lubricants including water and diluted syrup solutions at room temperature (25C) and body temperature (37C) by using simple pair-wise comparison to observe the just noticeable difference threshold and perception levels. Additionally, in this research applied force load during roughness observation was tested with pair-wise ranking method to illustrate its possible effect on human sensation. Obtained results showed that human's capability of roughness discrimination reduces with increased viscosity of the lubricant, where the influence of the temperature was not found to be significant. Moreover, the increase in the applied force load showed an increase in the sensitivity of roughness discrimination. Observed effects of the applied factors were also used for estimating the oral sensation of texture during eating. These findings are significant for our fundamental understanding to texture perception, and for the development of new food products with controlled textural features. Texture discrimination ability, more specifically roughness discrimination capability, is a significant factor for preference and appreciation for a wide range of materials, including food, furniture, or fabric. To explore the mechanism of sensation capability through tactile senses, it is necessary to identify the relevant factors and define characteristics that dominate the process involved. The results that will be obtained under these principles

  2. Soft Interval-Valued Neutrosophic Rough Sets

    Directory of Open Access Journals (Sweden)

    Said Broumi

    2015-01-01

    Full Text Available In this paper, we first defined soft interval-valued neutrosophic rough sets(SIVN- rough sets for short which combines interval valued neutrosophic soft set and rough sets and studied some of its basic properties. This concept is an extension of soft interval valued intuitionistic fuzzy rough sets( SIVIF- rough sets. Finally an illustrative example is given to verify the developped algorithm and to demonstrate its practicality and effectiveness.

  3. High Thrust-to-Power Annular Engine Technology

    Science.gov (United States)

    Patterson, Michael J.; Thomas, Robert E.; Crofton, Mark W.; Young, Jason A.; Foster, John E.

    2015-01-01

    Gridded ion engines have the highest efficiency and total impulse of any mature electric propulsion technology, and have been successfully implemented for primary propulsion in both geocentric and heliocentric environments with excellent ground/in-space correlation of performance. However, they have not been optimized to maximize thrust-to-power, an important parameter for Earth orbit transfer applications. This publication discusses technology development work intended to maximize this parameter. These activities include investigating the capabilities of a non-conventional design approach, the annular engine, which has the potential of exceeding the thrust-to-power of other EP technologies. This publication discusses the status of this work, including the fabrication and initial tests of a large-area annular engine. This work is being conducted in collaboration among NASA Glenn Research Center, The Aerospace Corporation, and the University of Michigan.

  4. Analysis of a Low-Angle Annular Expander Nozzle

    Directory of Open Access Journals (Sweden)

    Kyll Schomberg

    2015-01-01

    Full Text Available An experimental and numerical analysis of a low-angle annular expander nozzle is presented to observe the variance in shock structure within the flow field. A RANS-based axisymmetric numerical model was used to evaluate flow characteristics and the model validated using experimental pressure readings and schlieren images. Results were compared with an equivalent converging-diverging nozzle to determine the capability of the wake region in varying the effective area of a low-angle design. Comparison of schlieren images confirmed that shock closure occurred in the expander nozzle, prohibiting the wake region from affecting the area ratio. The findings show that a low angle of deflection is inherently unable to influence the effective area of an annular supersonic nozzle design.

  5. Wind Generated Rogue Waves in an Annular Wave Flume.

    Science.gov (United States)

    Toffoli, A; Proment, D; Salman, H; Monbaliu, J; Frascoli, F; Dafilis, M; Stramignoni, E; Forza, R; Manfrin, M; Onorato, M

    2017-04-07

    We investigate experimentally the statistical properties of a wind-generated wave field and the spontaneous formation of rogue waves in an annular flume. Unlike many experiments on rogue waves where waves are mechanically generated, here the wave field is forced naturally by wind as it is in the ocean. What is unique about the present experiment is that the annular geometry of the tank makes waves propagating circularly in an unlimited-fetch condition. Within this peculiar framework, we discuss the temporal evolution of the statistical properties of the surface elevation. We show that rogue waves and heavy-tail statistics may develop naturally during the growth of the waves just before the wave height reaches a stationary condition. Our results shed new light on the formation of rogue waves in a natural environment.

  6. Supercritical heat transfer in an annular channel with bilateral heating

    Energy Technology Data Exchange (ETDEWEB)

    Sergeev, V.V.; Gal' chenko, E.F.; Remizov, O.V.

    1986-09-01

    This paper presents the experimental investigation of the degradation of heat transfer accompanying an ascending flow of a steam-water mixture and the development of an engineering method for calculating supercritical heat transfer in a vertical annular channel with bilateral heating. The experimental setup is described. The temperature of the exothermic surfaces from the indications of the thermocouples are determined taking into account their individual calibration, the temperature drops in the wall, and thermal losses. The temperature distribution along the length and periphery of the exothermic surfaces of the annular channel is shown and the dependence of the critical steam content on the power fed to the outer wall of the channel with different mass velocities is presented.

  7. Thermo-Elastic Finite Element Analyses of Annular Nuclear Fuels

    Science.gov (United States)

    Kwon, Y. D.; Kwon, S. B.; Rho, K. T.; Kim, M. S.; Song, H. J.

    In this study, we tried to examine the pros and cons of the annular type of fuel concerning mainly with the temperatures and stresses of pellet and cladding. The inner and outer gaps between pellet and cladding may play an important role on the temperature distribution and stress distribution of fuel system. Thus, we tested several inner and outer gap cases, and we evaluated the effect of gaps on fuel systems. We conducted thermo-elastic-plastic-creep analyses using an in-house thermo-elastic-plastic-creep finite element program that adopted the 'effective-stress-function' algorithm. Most analyses were conducted until the gaps disappeared; however, certain analyses lasted for 1582 days, after which the fuels were replaced. Further study on the optimal gaps sizes for annular nuclear fuel systems is still required.

  8. Energy and Exergy Analysis of an Annular Thermoelectric Heat Pump

    Science.gov (United States)

    Kaushik, S. C.; Manikandan, S.; Hans, Ranjana

    2016-07-01

    In this paper, the concept of an annular thermoelectric heat pump (ATEHP) has been introduced. An exoreversible thermodynamic model of the ATEHP considering the Thomson effect in conjunction with Peltier, Joule and Fourier heat conduction has been investigated using exergy analysis. New expressions for dimensionless heating power, optimum current at the maximum energy, exergy efficiency conditions and dimensionless irreversibilities in the ATEHP are derived. The results show that the heating power, energy and exergy efficiency of the ATEHP are lower than the flat-plate thermoelectric heat pump. The effects of annular shape parameter ( S r = r 2 /r 1), dimensionless temperature ratio ( θ = T h /T c) and the electrical contact resistances on the heating power, energy/exergy efficiency of an ATEHP have been studied. This study will help in the designing of actual ATEHP systems.

  9. Shear flow of dense granular materials near smooth walls. II. Block formation and suppression of slip by rolling friction.

    Science.gov (United States)

    Shojaaee, Zahra; Brendel, Lothar; Török, János; Wolf, Dietrich E

    2012-07-01

    The role of rotational degrees of freedom and of microscopic contact properties at smooth walls in two dimensional planar shear has been investigated by contact dynamics simulations of round hard frictional particles. Our default system setup consists of smooth frictional walls, giving rise to slip. We show that there exists a critical microscopic friction coefficient at the walls, above which they are able to shear the granular medium. We observe distinctive features at this critical point, which to our knowledge have not been reported before. Activating rolling friction at smooth walls reduces slip, leading to similar shear behavior as for rough walls (with particles glued on their surface). Our simulations with rough walls are in agreement with previous results, provided the roughness is strong enough. In the limit of small roughness amplitude, however, the distinctive features of shearing with smooth walls are confirmed.

  10. Flow of viscoplastic fluids in eccentric annular geometries

    DEFF Research Database (Denmark)

    Szabo, Peter; Hassager, Ole

    1992-01-01

    A classification of flowfields for the flow of a Bingham fluid in general eccentric annular geometries is presented. Simple arguments show that a singularity can exist in the stress gradient on boundaries between zones with yielded and un-yielded fluid respectively. A Finite Element code is used...... to verify this property of the Bingham fluid. An analytical solution for the flowfield in case of small eccentricities is derived....

  11. Detonation propagation in annular arcs of condensed phase explosives

    Science.gov (United States)

    Ioannou, Eleftherios; Schoch, Stefan; Nikiforakis, Nikolaos; Michael, Louisa

    2017-11-01

    We present a numerical study of detonation propagation in unconfined explosive charges shaped as an annular arc (rib). Steady detonation in a straight charge propagates at constant speed, but when it enters an annular section, it goes through a transition phase and eventually reaches a new steady state of constant angular velocity. This study examines the speed of the detonation wave along the annular charge during the transition phase and at steady state, as well as its dependence on the dimensions of the annulus. The system is modeled using a recently proposed diffuse-interface formulation which allows for the representation of a two-phase explosive and of an additional inert material. The explosive considered is the polymer-bonded TATB-based LX-17 and is modeled using two Jones-Wilkins-Lee (JWL) equations of state and the ignition and growth reaction rate law. Results show that steady state speeds are in good agreement with experiment. In the transition phase, the evolution of outer detonation speed deviates from the exponential bounded growth function suggested by previous studies. We propose a new description of the transition phase which consists of two regimes. The first regime is caused by local effects at the outer edge of the annulus and leads to a dependence of the outer detonation speed on the angular position along the arc. The second regime is induced by effects originating from the inner edge of the annular charge and leads to the deceleration of the outer detonation until steady state is reached. The study concludes with a parametric study where the dependence of the steady state and the transition phase on the dimensions of the annulus is investigated.

  12. Pattern dynamics in an annular CO2 laser

    OpenAIRE

    Ramon, M.L. (M. L.); Meucci, R. (R.); Allaria, E.; Boccaletti, S.

    2000-01-01

    Competition among modes in an annular CO2 laser has been experimentally and numerically analyzed. During the coexistence of di erent patterns, each of them resulting from the interaction of two transverse modes with opposite angular momentum, chaos has been experimentally detected. A numerical model, derived from the Maxwell-Bloch equations and including symmetry breaking terms, enables the interpretation of the main experimental features.

  13. A modified Fourier solution for vibration analysis of moderately thick laminated annular sector plates with general boundary conditions, internal radial line and circumferential arc supports

    Directory of Open Access Journals (Sweden)

    Pang Fuzhen

    2017-01-01

    Full Text Available In this paper, a modified Fourier solution based on the first-order shear deformation theory is developed for the free vibration problem of moderately thick composite laminated annular sector plates with general boundary conditions, internal radial line and circumferential arc supports. In this solution approach, regardless of boundary conditions, the displacement and rotation components of the sector plate are written in the form of the trigonometric series expansion in which several auxiliary terms are added to ensure and accelerate the convergence of the series. Each of the unknown coefficients is taken as the generalized coordinate and determined using the Raleigh- Ritz method. The accuracy and reliability of the present solution are validated by the comparison with the results found in the literature, and numerous new results for composite laminated annular sector plates considering various kinds of boundary conditions are presented. Comprehensive studies on the effects of elastic restraint parameters, layout schemes and locations of line/arc supports are also made.New results are obtained for laminated annular sector plates subjected to elastic boundary restraints and arbitrary internal radial line and circumferential arc supports in both directions, and they may serve as benchmark solutions for future researches.

  14. Annular lesions of cutaneous sarcoidosis with granulomatous vasculitis.

    Science.gov (United States)

    Mizuno, Kana; Nguyen, Chuyen Thi Hong; Ueda-Hayakawa, Ikuko; Okamoto, Hiroyuki

    2017-05-01

    Sarcoidosis is known to be involved in diseases with vasculitis as sarcoid vasculitis. However, vasculitis in cutaneous sarcoidal lesions is extremely rare. Here we describe a case of sarcoidosis with multiple annular skin lesions with granulomatous vasculitis. A 62-year-old female was diagnosed with sarcoidosis by chest-abdominal computed tomographic examination and laboratory tests. The skin lesions had appeared on her lower limbs 2 years before. Physical examination showed multiple infiltrated annular eruptions on the lower extremities. A skin biopsy of an area of erythema showed multiple non-caseating epithelioid cell granulomas in the dermis and subcutaneous fat and granulomatous vasculitis with fibrinoid degeneration in the subcutaneous fat. There are two types of vasculitis in sarcoidosis: leukocytoclastic and granulomatous vasculitis. Ulcers and livedo were more common in granulomatous vasculitis than in leukocytoclastic vasculitis. The present case had unique annular skin lesions of sarcoidosis with granulomatous vasculitis. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Annular tautomerism: experimental observations and quantum mechanics calculations

    Science.gov (United States)

    Cruz-Cabeza, Aurora J.; Schreyer, Adrian; Pitt, William R.

    2010-06-01

    The use of MP2 level quantum mechanical (QM) calculations on isolated heteroaromatic ring systems for the prediction of the tautomeric propensities of whole molecules in a crystalline environment was examined. A Polarisable Continuum Model was used in the calculations to account for environment effects on the tautomeric relative stabilities. The calculated relative energies of tautomers were compared to relative abundances within the Cambridge Structural Database (CSD) and the Protein Data Bank (PDB). The work was focussed on 84 annular tautomeric forms of 34 common ring systems. Good agreement was found between the calculations and the experimental data even if the quantity of these data was limited in many cases. The QM results were compared to those produced by much faster semiempirical calculations. In a search for other sources of the useful experimental data, the relative numbers of known compounds in which prototropic positions were often substituted by heavy atoms were also analysed. A scheme which groups all annular tautomeric transformations into 10 classes was developed. The scheme was designed to encompass a comprehensive set of known and theoretically possible tautomeric ring systems generated as part of a previous study. General trends across analogous ring systems were detected as a result. The calculations and statistics collected on crystallographic data as well as the general trends observed should be useful for the better modelling of annular tautomerism in the applications such as computer-aided drug design, small molecule crystal structure prediction, the naming of compounds and the interpretation of protein—small molecule crystal structures.

  16. Direct Shear Behavior of Fiber Reinforced Concrete Elements

    Directory of Open Access Journals (Sweden)

    Hussein Al-Quraishi

    2018-01-01

    Full Text Available Improving the accuracy of load-deformation behavior, failure mode, and ultimate load capacity for reinforced concrete members subjected to in-plane loadings such as corbels, wall to foundation connections and panels need shear strength behavior to be included. Shear design in reinforced concrete structures depends on crack width, crack slippage and roughness of the surface of cracks. This paper illustrates results of an experimental investigation conducted to investigate the direct shear strength of fiber normal strength concrete (NSC and reactive powder concrete (RPC. The tests were performed along a pre-selected shear plane in concrete members named push-off specimens. The effectiveness of concrete compressive strength, volume fraction of steel fiber, and shear reinforcement ratio on shear transfer capacity were considered in this study. Furthermore, failure modes, shear stress-slip behavior, and shear stress-crack width behavior were also presented in this study. Tests’ results showed that volume fraction of steel fiber and compressive strength of concrete in NSC and RPC play a major role in improving the shear strength of concrete. As expectedly, due to dowel action, the shear reinforcement is the predominant factor in resisting the shear stress. The shear failure of NSC and RPC has the sudden mode of failure (brittle failure with the approximately linear behavior of shear stress-slip relationship till failure. Using RPC instead of NSC with the same amount of steel fibers in constructing the push-off specimen result in high shear strength. In NSC, shear strength influenced by the three major factors; crack surface friction, aggregate interlock and steel fiber content if present. Whereas, RPC has only steel fiber and cracks surface friction influencing the shear strength. Due to cementitious nature of RPC in comparisons with NSC, the RPC specimen shows greater cracks width. It is observed that the Mattock model gives very satisfactory

  17. Numerical and experimental study of disturbance wave development in vertical two-phase annular flow

    Science.gov (United States)

    Hewitt, Geoffrey; Yang, Junfeng; Zhao, Yujie; Markides, Christos; Matar, Omar

    2013-11-01

    The annular flow regime is characterized by the presence of a thin, wavy liquid film driven along the wall by the shear stress exerted by the gas phase. Under certain liquid film Reynolds numbers, large disturbance waves are observed to traverse the interface, whose length is typically on the order of 20 mm and whose height is typically on the order of 5 times the thickness of the thin (substrate) layer between the waves. Experimental wok has been conducted to study the disturbance wave onset by probing the local film thickness for different Reynolds numbers. It is observed the disturbance waves grow gradually from wavy initiation and form the ring-like structure. To predict the wavy flow field observed in the experiment, 3D CFD simulations are performed using different low Reynolds number turbulence models and Large Eddy Simulation. Modeling results confirm that there is recirculation within the waves, and that they as a packet of turbulence traveling over a laminar substrate film. We also predict the coalescence and the break-up of waves leading to liquid droplet entrainment into the gas core. Skolkovo Foundation, UNIHEAT project.

  18. Effects of Annular and Rectangular Confinement on the Hydrodynamics of Reacting, Swirling Jets

    Science.gov (United States)

    Emerson, Benjamin; Lieuwen, Tim

    2015-11-01

    In gas turbine combustors, flames are stabilized in the shear layers of swirling jets. In such devices, the flame's dynamics and its unsteady heat release are strongly governed by the fluid dynamics of the swirling jet flow. This unsteady heat release can couple with an acoustic mode of the combustor to cause a troublesome self-excited oscillation known as combustion instability. This coupling often occurs through the fluid dynamics, where the flame is dynamically wrinkled by acoustically excited vortical structures. This study uses linear stability analysis to study the effects of confinement on the fluid dynamics of reacting, swirling jets. Previous studies have explored confinement effects of an outer cylindrical wall. This study investigates other types of confinement. The analysis compares the classical arrangement, with flow through an outer cylindrical wall, to two other arrangements: flows through annular or rectangular confinements. The analysis shows that these confinement changes can have significant impacts on the instability growth rates, frequencies, and mode shapes. For example, changing a cylindrical confinement to a rectangular confinement tends to alter the hydrodynamic mode shape by straightening the nodal lines in the hydrodynamic velocity field.

  19. Study of development of disturbance waves in annular gas-liquid flow

    Science.gov (United States)

    Cherdantsev, Andrey V.; Cherdantsev, Mikhail V.; Isaenkov, Sergey V.; Markovich, Dmitriy M.

    2017-09-01

    Downstream development of disturbance waves properties in annular regime of gas - liquid flow was conducted in adiabatic air-water downwards flow in a vertical pipe with inner diameter of 11.7 mm. The measurements were conducted using brightness-based laser-induced fluorescence technique. Instantaneous distributions of local thickness of liquid film along one longitudinal section of the duct over the first 45 cm from the inlet were obtained with sampling frequency of 10 kHz. Based on these spatiotemporal plots, dependence of local average velocity of disturbance waves on downstream distance was obtained for a wide range of gas and liquid flow rates. Three main stages of flow development were identified: a stage prior to formation of disturbance waves, a stage of constant acceleration of disturbance waves and a stage of deceleration nearly compensating the initial acceleration. Transitions to both second and third stages occur closer to the inlet at higher gas velocities and lower liquid flow rates. The initial acceleration is defined by the effect of the gas shear; it grows in parabolic manner with superficial gas velocity and shows weak dependence on liquid flow rate. The deceleration is supposed to occur due to entrainment of liquid from disturbance waves.

  20. Performance of an Annular Linear Induction Pump with Applications to Space Nuclear Power Systems

    Science.gov (United States)

    Polzin, Kurt A.; Schoenfeld, Michael; Pearson, J. Boise; Webster, Kenneth; Godfroy, Thomas; Adkins, Harold E., Jr.; Werner, James E.

    2010-01-01

    Results of performance testing of an annular linear induction pump are presented. The pump electromagnetically pumps liquid metal through a circuit specially designed to allow for quantification of the performance. Testing was conducted over a range of conditions, including frequencies of 33, 36, 39, and 60 Hz, liquid metal temperatures from 125 to 525 C, and input voltages from 5 to 120 V. Pump performance spanned a range of flow rates from roughly 0.16 to 5.7 L/s (2.5 to 90 gpm), and pressure head less than 1 to 90 kPa (less than 0.145 to 13 psi). The maximum efficiency measured during testing was slightly greater than 6%. The efficiency was fairly insensitive to input frequency from 33 to 39 Hz, and was markedly lower at 60 Hz. In addition, the efficiency decreased as the NaK temperature was raised. The performance of the pump operating on a variable frequency drive providing 60 Hz power compared favorably with the same pump operating on 60 Hz power drawn directly from the electrical grid.

  1. Variance reduction techniques for 14 MeV neutron streaming problem in rectangular annular bent duct

    Energy Technology Data Exchange (ETDEWEB)

    Ueki, Kotaro [Ship Research Inst., Mitaka, Tokyo (Japan)

    1998-03-01

    Monte Carlo method is the powerful technique for solving wide range of radiation transport problems. Its features are that it can solve the Boltzmann`s transport equation almost without approximation, and that the complexity of the systems to be treated rarely becomes a problem. However, the Monte Carlo calculation is always accompanied by statistical errors called variance. In shielding calculation, standard deviation or fractional standard deviation (FSD) is used frequently. The expression of the FSD is shown. Radiation shielding problems are roughly divided into transmission through deep layer and streaming problem. In the streaming problem, the large difference in the weight depending on the history of particles makes the FSD of Monte Carlo calculation worse. The streaming experiment in the 14 MeV neutron rectangular annular bent duct, which is the typical streaming bench mark experiment carried out of the OKTAVIAN of Osaka University, was analyzed by MCNP 4B, and the reduction of variance or FSD was attempted. The experimental system is shown. The analysis model by MCNP 4B, the input data and the results of analysis are reported, and the comparison with the experimental results was examined. (K.I.)

  2. Numerical modelling of borehole ballooning/breathing : effect of fracture roughness

    Energy Technology Data Exchange (ETDEWEB)

    Ozdemirtas, M.; Babadagli, T.; Kuru, E. [Alberta Univ., Edmonton, AB (Canada)

    2007-07-01

    A common observation during drilling of fractured zones is borehole ballooning or breathing which involves small, partial and continuous mud losses and considerable rapid mud gains due to annular pressure fluctuations resulting from mud circulation and non-circulation. In order to interpret the symptoms observed while drilling and to avoid mixing this phenomenon with lost circulation and well kicks, there is a need for a better understanding of the factors controlling borehole ballooning and/or breathing. This paper presented a two dimensional transient model of borehole ballooning and/or breathing that considered the effects of Newtonian fluid rheology, and fracture roughness on the fracture volume change as a function of transient wellbore pressure fluctuations encountered in common drilling operations. The study considered different types of fracture surface roughness that were commonly observed in sedimentary rocks and the degree of roughness identified by a different fractal dimensions. In order to examine the effects of the natural geologic properties of fractures on the fluid loss and gain rate between the borehole and the fractured formation, a numerical analysis was conducted. The paper also presented an analysis of the importance of fracture roughness and non-linear deformation approximations. Situations where the degree of roughness became critical were also examined. It was concluded that fracture surface roughness had a significant effect on the magnitude of mud gain/loss events and that increasing fracture surface roughness and partially closing walls of the fracture reduced the mud gain and loss flow rates. 12 refs., 1 tab., 11 figs.

  3. Sensing roughness and polish direction

    DEFF Research Database (Denmark)

    Jakobsen, Michael Linde; Olesen, Anders Sig; Larsen, Henning Engelbrecht

    2016-01-01

    and time consumption can become prohibitive in a research budget. Machining the optical surfaces directly is expensive and time consuming. Alternatively, a more standardized and cheaper machining method can be used, calling for the object to be manually polished. During the polishing process, the operator...... needs information about the RMS-value of the surface roughness and the current direction of the scratches introduced by the polishing process. The RMS-value indicates to the operator how far he is from the final finish, and the scratch orientation is often specified by the customer in order to avoid...... complications during the casting process. In this work we present a method for measuring the RMS-values of the surface roughness while simultaneously determining the polishing direction. We are mainly interested in the RMS-values in the range from 0 – 100 nm, which corresponds to the finish categories of A1, A2...

  4. Sensing roughness and polish direction

    Science.gov (United States)

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

    2016-04-01

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

  5. Development of a thermal-hydraulic analysis code for annular fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Vishnoi, A.K.; Chandraker, D.K.; Vijayan, P.K. [Bhabha Atomic Reseach Centre (BARC), Mumbai, Maharashtra (India)

    2012-03-15

    In this work a detailed study of the annular fuel has been carried out. A thermal hydraulics code, ANUFAN (Annular Fuel Analysis), based on the bundle average method, capable of modeling both internally and externally cooled annular fuel pins is developed. Code predictions have been compared with calculations from Korea Atomic Energy Research Institute (KAERI) and MIT. Heat transfer fraction difference between ANUFAN and RELAP was found about 1.7%. Analysis of a 54 - fuel rod assembly is carried out with 36 and 45 numbers of annular fuel pins keeping the same channel size and bundle power as of the solid fuel assembly. Fuel pin maximum temperature of the annular fuel is found much less than the solid fuel. MCHFR value for annular fuel is found much higher compared to that of the solid fuel of 54 - fuel rod assembly. The full paper covers the details of the computer code, the analysis carried out and the results obtained. (orig.)

  6. Annular rupture during transcatheter aortic valve replacement: classification, pathophysiology, diagnostics, treatment approaches, and prevention.

    Science.gov (United States)

    Pasic, Miralem; Unbehaun, Axel; Buz, Semih; Drews, Thorsten; Hetzer, Roland

    2015-01-01

    Annular rupture is an umbrella term covering different procedural-related injuries that may occur in the region of the aortic root and the left ventricular outflow tract during transcatheter aortic valve replacement. According to the anatomical location of the injury, there are 4 main types: supra-annular, intra-annular, subannular, and combined rupture. Annular rupture is a rare, unpredictable, and potentially fatal complication. It can be treated successfully if it is immediately recognized and adequately managed. The type of therapy depends on the location of the annular rupture and the nature of the clinical manifestations. Treatment approaches include conventional cardiac procedure, isolated pericardial drainage, and conservative therapy. This summary describes theoretical and practical considerations of the etiology, pathophysiology, classification, natural history, diagnostic and treatment strategies, and prevention approaches of annular rupture. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  7. The effects of roughness and offset on fracture compliance ratio

    Science.gov (United States)

    Ahmadi, M.; Taleghani, A. Dahi; Sayers, C. M.

    2016-04-01

    Fractures are a source of extra compliance in the rock mass. The mechanical properties of the rock matrix as well as the propagation of seismic waves inside the rock medium are dependent on the magnitude of roughness and offset between the imperfect fracture interfaces. Fracture compliance can estimate the degree of contact between fracture faces, type of fluid filling the fracture and the fracture roughness. To characterize these fracture properties, compliance ratio, known by the ratio of normal-to-shear compliance, can be a potential tool in the subsurface studies to improve the well layout design. The focus of this study is to illustrate how the compliance ratio of a rough fracture, with or without the offset between the fracture faces, can diverge from the compliance ratio of a fracture with smooth interface. Quasi-static and dynamic methods are two common ways to calculate the compliance. The former calculates the compliance by measuring the change in the displacement with the applied stress, while the latter estimates the compliance through monitoring the changes in propagation of seismic waves. To compare the compliance ratios of fractures with imperfect and smooth interfaces in an infinite medium, a numerical finite-element model is built in commercial finite-element software. The imperfect interface of the fracture is modeled with saw-tooth-like structures where they can be partially or fully in contact. The defined saw-tooth-like structures of contact asperities impose an in-plane asymmetry in the shear direction. This asymmetry causes two different values for the compliance in shear direction, known as the soft and stiff shear compliance. Our numerical simulations suggest the increase in the degree of contact between the fracture faces increases the compliance ratio in the stiff direction more than the soft direction. The compliance ratio of the fracture with the imperfect interface is larger than the compliance ratio of the smooth fracture. We suggest

  8. Inverse magnetic/shear catalysis

    Directory of Open Access Journals (Sweden)

    Brett McInnes

    2016-05-01

    Full Text Available It is well known that very large magnetic fields are generated when the Quark–Gluon Plasma is formed during peripheral heavy-ion collisions. Lattice, holographic, and other studies strongly suggest that these fields may, for observationally relevant field values, induce “inverse magnetic catalysis”, signalled by a lowering of the critical temperature for the chiral/deconfinement transition. The theoretical basis of this effect has recently attracted much attention; yet so far these investigations have not included another, equally dramatic consequence of the peripheral collision geometry: the QGP acquires a large angular momentum vector, parallel to the magnetic field. Here we use holographic techniques to argue that the angular momentum can also, independently, have an effect on transition temperatures, and we obtain a rough estimate of the relative effects of the presence of both a magnetic field and an angular momentum density. We find that the shearing angular momentum reinforces the effect of the magnetic field at low values of the baryonic chemical potential, but that it can actually decrease that effect at high chemical potentials.

  9. Low Rm magnetohydrodynamics as a means of measuring the surface shear viscosity of a liquid metal: A first attempt on Galinstan.

    Science.gov (United States)

    Delacroix, Jules; Davoust, Laurent; Patouillet, Kévin

    2018-01-01

    This paper introduces an experimental apparatus which generates the end-driven annular flow of a liquid metal pervaded by a uniform magnetic field. Unlike past viscometers involving an annular channel with particular values of the depth-to-width ratio, the present experiment enables us to drive the viscous shear at the surface of an annular liquid metal bath put in rotation. The magnetic interaction parameter N and the Boussinesq number related to the surface shear viscosity can be monitored from the magnitude of the applied magnetic field; the latter being set large enough for avoiding artefacts related to centrifugation and surface dilatation. This essential feature is obtained due to the ability of the magnetic field to set dimensionality of the annular flow in the channel between 2D-1/2 (swirling flow) and 2D axisymmetric (extinction of the overturning flow if N is large enough). By tracking the azimuthal velocity of tracers seeded along the oxidised surface of liquid Galinstan, an estimate for the surface shear viscosity of a liquid metal can be given.

  10. Core-annular flow through a horizontal pipe: hydrodynamic counterbalancing of buoyancy force on core

    OpenAIRE

    Ooms, G.; Vuik, C.; Poesio, P.

    2008-01-01

    A theoretical investigation has been made of core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe. Special attention is paid to the question of how the buoyancy force on the core, caused by a density difference between the core and the annular layer, is counterbalanced. From earlier studies it is known that at the interface between the annular layer and the core waves are present that move with respect to the ...

  11. Electron beam diagnostic system using computed tomography and an annular sensor

    Science.gov (United States)

    Elmer, John W.; Teruya, Alan T.

    2015-08-11

    A system for analyzing an electron beam including a circular electron beam diagnostic sensor adapted to receive the electron beam, the circular electron beam diagnostic sensor having a central axis; an annular sensor structure operatively connected to the circular electron beam diagnostic sensor, wherein the sensor structure receives the electron beam; a system for sweeping the electron beam radially outward from the central axis of the circular electron beam diagnostic sensor to the annular sensor structure wherein the electron beam is intercepted by the annular sensor structure; and a device for measuring the electron beam that is intercepted by the annular sensor structure.

  12. Pancreaticoduodenectomy for pancreas carcinoma occurring in the annular pancreas: report of a case.

    Science.gov (United States)

    Kawaida, Hiromichi; Kono, Hiroshi; Watanabe, Mitsuaki; Maki, Akira; Amemiya, Hidetake; Matsuda, Masanori; Fujii, Hideki; Fukasawa, Mitsuharu; Takahashi, Ei; Sano, Katsuhiro; Inoue, Tomohiro

    2015-08-01

    The annular pancreas is a rare congenital anomaly in which a ring of the pancreas parenchyma surrounds the second part of the duodenum. Malignant tumors are extremely rare in patients with an annular pancreas. A 64-year-old man presented with appetite loss and vomiting. Abdominal contrast-enhanced computed tomography (CT) indicated pancreas parenchyma surrounding the second part of the duodenum, and a hypovascular area occupying lesion in the annular pancreas. Subtotal stomach-preserving pancreaticoduodenectomy was performed. Histopathology showed pancreatic carcinoma occurring in the complete annular pancreas.

  13. On the Determination of Effective Aerodynamic Roughness of Surfaces with Vegetation Patches

    Science.gov (United States)

    Lopes, A. Silva; Palma, J. M. L. M.; Piomelli, U.

    2015-07-01

    Large-eddy simulations of the flow over surfaces with alternating forest patches and clearings of different horizontal scale were performed, modelling the forest canopies as a horizontally homogeneous drag field. The objective was to extend previous works that studied the flow over sudden changes in aerodynamic roughness length occurring typically in the transition between small vegetation and forest but neglected the variations of displacement height. It was found that the internal boundary layers that formed in the transition between surface patches initially grew similarly for both the sudden changes of roughness and the alternating forest patches and clearings, but the turbulence produced at the tops of trees could break the regular growth, increasing the vertical propagation of surface heterogeneity and, consequently, the blending height. Also, the forest patches enhanced the Reynolds shear stress at the tree height over the clearings: when the energy extraction by the forest canopy ceased, the turbulent fluctuations increased and the turbulent shear production was kept high over much of the following clearing. Consequently, the Reynolds shear stress over the clearings decayed slowly, or not at all in the case of short patches. This resulted in higher average shear stress and effective aerodynamic roughness length than was the case when variations of displacement height were neglected.

  14. Quantitative roughness measurements with iTIRM

    NARCIS (Netherlands)

    Bijl, R.J.M. van der; Fähnle, O.W.; Brug, H. van; Braat, J.J.M.

    2000-01-01

    A new method, iTIRM, is used for quantitative surface roughness measurements of ground and polished surfaces and it is shown to be a useful tool for measuring total surface quality instead of individual roughness parameters.

  15. Effects of surface roughness and energy on ice adhesion strength

    Energy Technology Data Exchange (ETDEWEB)

    Zou, M., E-mail: mzou@uark.edu [Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Beckford, S. [Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Wei, R.; Ellis, C. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States); Hatton, G. [Shell Global Solutions, Inc., Houston, TX 77210 (United States); Miller, M.A. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States)

    2011-02-01

    The aim of this study is to investigate the effects of surface roughness and surface energy on ice adhesion strength. Sandblasting technique was used to prepare samples with high roughness. Silicon-doped hydrocarbon and fluorinated-carbon thin films were employed to alter the surface energy of the samples. Silicon-doped hydrocarbon films were deposited by plasma-enhanced chemical vapor deposition, while fluorinated-carbon films were produced using deep reactive ion etching equipment by only activating the passivation step. Surface topographies were characterized using scanning electron microscopy and a stylus profilometer. The surface wetting properties were characterized by a video-based contact angle measurement system. The adhesion strength of ice formed from a water droplet on these surfaces was studied using a custom-built shear force test apparatus. It was found that the ice adhesion strength is correlated to the water contact angles of the samples only for surfaces with similar roughness: the ice adhesion strength decreases with the increase in water contact angle. The study also shows that smoother as-received sample surfaces have lower ice adhesion strength than the much rougher sandblasted surfaces.

  16. Calibration of surface roughness standards

    DEFF Research Database (Denmark)

    Thalmann, R.; Nicolet, A.; Meli, F.

    2016-01-01

    the number of inconsistent results could be reduced to 20, which correspond to about 5% of the total and can statistically be expected. In addition to the material standards, two softgauges were circulated, which allow to test the software of the instruments used in the comparison. The comparison results......The key comparison EURAMET.L-K8.2013 on roughness was carried out in the framework of a EURAMET project starting in 2013 and ending in 2015. It involved the participation of 17 National Metrology Institutes from Europe, Asia, South America and Africa representing four regional metrology...

  17. Electrokinetic transport in microchannels with random roughness

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Moran [Los Alamos National Laboratory; Kang, Qinjun [Los Alamos National Laboratory

    2008-01-01

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

  18. Fetlock annular ligament desmotomy: a report of 24 cases.

    Science.gov (United States)

    Gerring, E L; Webbon, P M

    1984-03-01

    Restriction of free movement of the flexor tendons through the fetlock canal results in lameness. The commonest cause was chronic synovitis of the digital sheath. The condition is characterised by an unremitting lameness, synovial distension and a notch on the caudal aspect of the limb. The condition can be relieved by section of the annular ligament of the fetlock. In a series of 24 cases 16 horses returned to work with no recurrence of lameness, three cases were lost to follow up and five animals remained lame; three of these had intercurrent disease.

  19. Pressure Drop in Vertical Core-Annular Flow

    OpenAIRE

    Prada,José Walter Vanegas; Bannwart,Antonio Carlos

    2001-01-01

    An experimental apparatus for the study of core annular flows of heavy oil and water at room temperature has been set up and tested at laboratory scale. The test section consists of a 2.75 cm ID galvanized steel pipe. Tap water and a heavy oil (17.6 Pa.s; 963 kg/m³) were used. Pressure drop in a vertical upward test section was accurately measured for oil flow rates in the range 0.297 - 1.045 l/s and water flow rates ranging from 0.063 to 0.315 l/s. The oil-water input ratio was in the range ...

  20. Study and optimization of an annular photocatalytic slurry reactor.

    Science.gov (United States)

    Camera-Roda, Giovanni; Santarelli, Francesco; Panico, Mauro

    2009-05-01

    The experimental results obtained for the photocatalytic degradation of a model organic dye in an annular slurry reactor are analyzed with the aid of a mathematical model. The model is used also to study the effects on the performances of many operative conditions: flow rate, photocatalyst concentration, power of the lamp, size of the photocatalytic particles, dimensions of the reactor. The investigation demonstrates that the rate of the process is often limited by the radiant energy transfer and that some simple rules can be followed in order to optimize different yields and the observed rate of reaction.

  1. Coexistence of disseminated granuloma annulare and asymptomatic multiple myeloma

    Directory of Open Access Journals (Sweden)

    Şebnem Aktan

    2013-09-01

    Full Text Available Granuloma annulare (GA is a benign inflammatory dermatosis of unknown cause, characterized by necrobiotic dermal papules. Several morphologic forms of GA including localized, disseminated, linear, nodular, perforating, subcutaneous, pustular and arcuate dermal erythema have been reported in the literature. Disseminated GA, a rarely seen form, has been reported in association with some hematopoietic and solid malignancies; however, it has been suggested that the exact causative relationship between malignancy and GA is unclear. We present here a 66-year-old female patient with disseminated GA associated with asymptomatic multipl myeloma.

  2. Understanding Wave-mean Flow Feedbacks and Tropospheric Annular Variability

    Science.gov (United States)

    Lorenz, D. J.

    2016-12-01

    The structure of internal tropospheric variability is important for determining the impact of the stratosphere on the troposphere. This study aims to better understand the fundamental dynamical mechanisms that control the feedbacks between the eddies and the mean flow, which in turn select the tropospheric annular mode. Recent work using Rossby Wave Chromatography suggests that "barotropic processes", which directly impact the meridional propagation of wave activity (specifically the reflectivity of the poleward flank of the mid-latitude jet), are more important for the positive feedback between the annular mode and the eddies than "baroclinic processes", which involve changes in the generation of wave activity by baroclinic instability. In this study, experiments with a fully nonlinear quasi-geostrophic model are discussed which provide independent confirmation of the importance of barotropic versus baroclinic processes. The experiments take advantage of the steady-state balance at upper-levels between the meridional gradient in diabatic heating and the second derivative of the upper-level EP flux divergence. Simulations with standard Newtonian heating are compared to simulations with constant-in-time heating taken from the climatology of the standard run and it is found that the forced annular mode response to changes in surface friction is very similar. Moreover, as expected from the annular mode response, the eddy momentum fluxes are also very similar. This is despite the fact that the upper-level EP flux divergence is very different between the two simulations (upper-level EP flux divergence must remain constant in the constant heating simulation while in the standard simulation there is no such constraint). The upper-level balances are maintained by a large change in the baroclinic wave source (i.e. vertical EP flux), which is accompanied by little momentum flux change. Therefore the eddy momentum fluxes appear to be relatively insensitive to the wave

  3. Unusual Presentation of Acute Annular Urticaria: A Case Report

    Science.gov (United States)

    Guerrier, Gilles; Daronat, Jean-Marc; Deltour, Roger

    2011-01-01

    Acute urticarial lesions may display central clearing with ecchymotic or haemorrhagic hue, often misdiagnosed as erythema multiforme, serum-sickness-like reactions, or urticarial vasculitis. We report a case of acute annular urticaria with unusual presentation occurring in a 20-month-old child to emphasize the distinctive morphologic manifestations in a single disease. Clinicians who care for children should be able to differentiate acute urticaria from its clinical mimics. A directed history and physical examination can reliably orientate necessary diagnostic testing and allow for appropriate treatment. PMID:23198178

  4. Unusual Presentation of Acute Annular Urticaria: A Case Report

    Directory of Open Access Journals (Sweden)

    Gilles Guerrier

    2011-01-01

    Full Text Available Acute urticarial lesions may display central clearing with ecchymotic or haemorrhagic hue, often misdiagnosed as erythema multiforme, serum-sickness-like reactions, or urticarial vasculitis. We report a case of acute annular urticaria with unusual presentation occurring in a 20-month-old child to emphasize the distinctive morphologic manifestations in a single disease. Clinicians who care for children should be able to differentiate acute urticaria from its clinical mimics. A directed history and physical examination can reliably orientate necessary diagnostic testing and allow for appropriate treatment.

  5. Final Technical Report for the MIT Annular Fuel Research Project

    Energy Technology Data Exchange (ETDEWEB)

    Mujid S. Kazimi; Pavel Hejzlar

    2008-01-31

    MIT-NFC-PR-082 (January 2006) Abstract This summary provides an overview of the results of the U.S. DOE funded NERI (Nuclear Research ENergy Initiative) program on development of the internally and externally cooled annular fuel for high power density PWRs. This new fuel was proposed by MIT to allow a substantial increase in poer density (on the order of 30% or higher) while maintaining or improving safety margins. A comprehensive study was performed by a team consisting of MIT (lead organization), Westinghuse Electric Corporation, Gamma Engineering Corporation, Framatome ANP(formerly Duke Engineering) and Atomic Energy of Canada Limited.

  6. Critical bed shear stress and threshold of motion of maerl biogenic gravel

    Science.gov (United States)

    Joshi, Siddhi; Duffy, Garret Patrick; Brown, Colin

    2017-07-01

    A determination of the critical bed shear stress of maerl is a prerequisite for quantifying its mobility, rate of erosion and deposition in conservation management. The critical bed shear stress for incipient motion has been determined for the first time for samples from biogenic free-living maerl beds in three contrasting environments (open marine, intertidal and beach) in Galway Bay, west of Ireland. The bed shear stress was determined using two methods, Law of the Wall and Turbulent Kinetic Energy, in a rotating annular flume and in a linear flume. The velocity profile of flowing water above a bed of natural maerl grains was measured in four runs of progressively increasing flow velocity until the flow exceeded the critical shear stress of grains on the bed. The critical Shields parameter and the mobility number are estimated and compared with the equivalent curves for natural quartz sand. The critical Shields parameters for the maerl particles from all three environments fall below the Shields curve. Along with a previously reported correlation between maerl grain shape and settling velocity, these results suggest that the highly irregular shapes also allow maerl grains to be mobilised more easily than quartz grains with the same sieve diameter. The intertidal beds with the roughest particles exhibit the greatest critical shear stress because the particle thalli interlock and resist entrainment. In samples with a high percentage of maerl and low percentage of siliciclastic sand, the lower density, lower settling velocity and lower critical bed shear stress of maerl results in its preferential transport over the siliciclastic sediment. At velocities ∼10 cm s-1 higher than the threshold velocity of grain motion, rarely-documented subaqueous maerl dunes formed in the annular flume.

  7. Physical Measurements of Sea Bed Roughness

    Science.gov (United States)

    Nunes, V. B.; Pawlak, G.

    2004-12-01

    Physical measurements of sea bed roughness were obtained using a boat-mounted acoustic altimetry system combined with diver-based observations with the goal of resolving scales between 10 and 100cm. The surveyed area extends from the wave breaking zone to a depth of 20 m and is characterized by a highly inhomogeneous sea bed. Theory suggests that these roughness scales play an important role in wave energy dissipation, despite the lack of established parameterizations for these high roughness regimes. This study attempts to address this issue by investigating methods for quantifying roughness and examining the relationships between physical and hydrodynamic roughness. Results show a significant variation of roughness over the study area indicating limitations in defining a single scale for the shallow water region. Various statistical estimators are examined as potential candidates for roughness parameterization schemes, including rms, standard deviation and consecutive angle difference in order to characterize bed morphologies. Wave number spectral analysis is used to highlight the dominant roughness scales. The analysis is directed towards merging the various roughness parameters with wave field observations and numerical wave model output, to produce a roughness map that establishes a link between the physical roughness measurements and hydrodynamic wave friction at the study area.

  8. Adhesion of liquid droplets to rough surfaces.

    Science.gov (United States)

    Li, Ri; Alizadeh, Azar; Shang, Wen

    2010-10-01

    We study the adhesion of liquid droplets to rough surfaces, focusing on how adhesion changes with surface chemistry and roughness. For hydrophobic surfaces (equilibrium contact angle θ(e)>90°), although increasing surface roughness augments apparent contact angle, it does not necessarily always reduce adhesion. In a domain defined by roughness and equilibrium contact angle, this study identifies regions where adhesion increases or decreases with increasing roughness. The two regions do not border at θ(e)=90°. It is found that making surfaces with low roughness ratio (close to 1) does not reduce adhesion unless the surface material is highly hydrophobic (θ(e)>120°). In other words, to reduce adhesion for existing hydrophobic materials (90°adhesion, the geometry of microstructures should be designed such that wetted fraction decreases with increasing roughness ratio. This study is of particular importance for the design of textured superhydrophobic surfaces.

  9. A Compact Annular Ring Microstrip Antenna for WSN Applications

    Directory of Open Access Journals (Sweden)

    Daihua Wang

    2012-06-01

    Full Text Available A compact annular ring microstrip antenna was proposed for a wireless sensor network (WSN application in the 2.4 GHz band. In this paper the major considerations of the conformal antenna design were the compact size and the impact on antenna’s performance of a steel installation base. By using a chip resistor of large resistance (120 Ω the antenna size was reduced to 38% of that a conventional annular ring patch antenna. With the addition of the steel installation base the resonant frequency of the antenna increases about 4.2% and the bandwidth reduces from 17.5% to 11.7% by adjusting the load resistance simultaneously. Several key parameters were discussed and optimized, and the antenna was fabricated and its performance measured. The antenna is well matched at 2.4 GHz with 34.2 dB return loss and –2.5 dBi peak gain. Meanwhile, it exhibits excellent radiation patterns with very low cross-polarization levels.

  10. Annular dark field transmission electron microscopy for protein structure determination

    Energy Technology Data Exchange (ETDEWEB)

    Koeck, Philip J.B., E-mail: Philip.Koeck@ki.se

    2016-02-15

    Recently annular dark field (ADF) transmission electron microscopy (TEM) has been advocated as a means of recording images of biological specimens with better signal to noise ratio (SNR) than regular bright field images. I investigate whether and how such images could be used to determine the three-dimensional structure of proteins given that an ADF aperture with a suitable pass-band can be manufactured and used in practice. I develop an approximate theory of ADF-TEM image formation for weak amplitude and phase objects and test this theory using computer simulations. I also test whether these simulated images can be used to calculate a three-dimensional model of the protein using standard software and discuss problems and possible ways to overcome these. - Highlights: • I present theory and simulations for imaging proteins using annular dark field transmission electron microscopy and investigate its suitability for 3D-reconstruction. • I show that the images are approximately proportional to the square of the projected electrostatic potential within a given passband ). • 3D-reconstructions show errors in the interior of the molecule. More accurate maps might be calculated by reconstruction algorithms that take into account non-linear image formation.

  11. Experimental and theoretical studies of vertical annular liquid jets

    Science.gov (United States)

    Chigier, Norman; Ramos, J. I.; Kihm, K. D.

    1988-05-01

    The objectives of this study are to determine the stability, dynamics, and convergence of vertical annular liquid jets as a function of the initial radius, sheet thickness, and velocity. The influence of variation of Froude, Reynolds, and Weber numbers and geometry on convergence and stability are examined. An implicit finite-difference scheme is developed for solution of the steady-state and time-dependent axisymmetric Navier-Stokes equations. In collaboration with Westinghouse, a cylindrical film chemical reactor will be designed for control of reactions such as reduction of zirconium. Annular liquid curtains have been formed with an initial curtain radius of 50 mm and initial sheet thicknesses of 0.5 and 1.0 mm. Three Froude numbers have been studied: 1.27, 4.27, and 8.87 with variation of the liquid flow rate. Pressure within the curtains has been varied progressively from 0 to 3 Pa. Several flow regimes were found: (1) non-pressurized, (2) pressurized, (3) oscillating, and (4) punctured. Curtain shape and convergence length were determined for each condition by photography. Axial mean velocity in the liquid curtain was measured by Laser Doppler Anemometry along the length of the curtain. The variation of liquid film thickness with axial distance was determined.

  12. Linear and nonlinear stability of periodic orbits in annular billiards.

    Science.gov (United States)

    Dettmann, Carl P; Fain, Vitaly

    2017-04-01

    An annular billiard is a dynamical system in which a particle moves freely in a disk except for elastic collisions with the boundary and also a circular scatterer in the interior of the disk. We investigate the stability properties of some periodic orbits in annular billiards in which the scatterer is touching or close to the boundary. We analytically show that there exist linearly stable periodic orbits of an arbitrary period for scatterers with decreasing radii that are located near the boundary of the disk. As the position of the scatterer moves away from a symmetry line of a periodic orbit, the stability of periodic orbits changes from elliptic to hyperbolic, corresponding to a saddle-center bifurcation. When the scatterer is tangent to the boundary, the periodic orbit is parabolic. We prove that slightly changing the reflection angle of the orbit in the tangential situation leads to the existence of Kolmogorov-Arnold-Moser islands. Thus, we show that there exists a decreasing to zero sequence of open intervals of scatterer radii, along which the billiard table is not ergodic.

  13. Numerical Simulation of Barite Sag in Pipe and Annular Flow

    Directory of Open Access Journals (Sweden)

    Patrick Kabanda

    2017-01-01

    Full Text Available With the ever increasing global energy demand and diminishing petroleum reserves, current advances in drilling technology have resulted in numerous directional wells being drilled as operators strive to offset the ever-rising operating costs. In as much as deviated-well drilling allows drillers to exploit reservoir potential by penetrating the pay zone in a horizontal, rather than vertical, fashion, it also presents conditions under which the weighting agents can settle out of suspension. The present work is categorized into two parts. In the first part, governing equations were built inside a two-dimensional horizontal pipe geometry and the finite element method utilized to solve the equation-sets. In the second part, governing equations were built inside a three-dimensional horizontal annular geometry and the finite volume method utilized to solve the equation-sets. The results of the first part of the simulation are the solid concentration, mixture viscosity, and a prediction of the barite bed characteristics. For the second part, simulation results show that the highest occurrence of barite sag is at low annular velocities, nonrotating drill pipe, and eccentric drill pipe. The CFD approach in this study can be utilized as a research study tool in understanding and managing the barite sag problem.

  14. Annular bullous lesions with atypical erythema multiforme in leprosy.

    Science.gov (United States)

    Shah, Aishani; Mahajan, Rashmi; Ninama, Kishan; Bilimoria, Freny

    2014-09-01

    Erythema nodosum leprosum (ENL) is an immune complex-mediated reaction that may complicate the course of multibacillary leprosy. Bullous lesions in Type II reaction, though reported, are exceedingly rare. We report the case of a 32 year old female patient who presented initially at our OPD with erythema nodosum. Cutaneous examination revealed impaired sensation over dorsum of right foot and thickened right lateral popliteal nerve. Slit skin smear (SSS) from ear lobes revealed AFB with a bacteriological index of 2+. She was started on MDT, tablet ofloxacin 200 mg twice a day, and 30 mg oral prednisolone. Two months later, she presented with generalised pruritus, large target lesions over the back, and hemorrhagic bullae over lower extremities and annular pattern of bullae, over both arms. A SSS was repeated which was positive for AFB. Histopathology from bullous lesions was consistent with ENL. Direct Immunofluorescence (DIF) study was negative. Our patient improved rapidly after she was started on thalidomide 100 mg twice daily, with withdrawal of ofloxacin. Erythema Multiforme (EMF) and annular bullous lesions have been reported in patients on treatment with ofloxacin. This case is being presented due to the unusual and varied manifestation of Type II lepra reaction in a 34 year old female patient.

  15. Granuloma anular perfurante generalizado Generalized perforating granuloma annulare

    Directory of Open Access Journals (Sweden)

    Sérgio Ivan Torres Dornelles

    2011-04-01

    Full Text Available Os autores apresentam caso clínico-patológico de Granuloma Anular Perfurante Generalizado, com extensa distribuição de lesões, as quais se mostram em diversas fases de evolução. Pústulas, lesões papulosas, em distribuição anular e arciforme, erosões recobertas por crostas hemáticas, áreas máculo atróficas e cicatrizes foram as faces de apresentação da doença. Os aspectos histopatopatológicos são detalhadamente discutidos, dentro das dermatites granulomatosas não infecciosas. O texto baseia-se nas opiniões de alguns autores da literatura. Além disso, o resultado terapêutico obtido foi demonstrado por fotografias, resultado de 3 meses de Dapsona na dose de 100 mg por dia.The authors present a clinicopathological case of Generalized Perforating Granuloma Annulare with extensive distribution of lesions, which are shown in various stages of development. Pustules, papular lesions in annular and arcuate distribution, erosions covered with hematic crusts, maculopapular atrophic areas and scars were the presentation forms of the disease. The histopathological aspects are discussed in detail within non-infectious granulomatous dermatitis. The text is based on the opinions of some authors in the literature. Furthermore, the therapeutic result obtained after three months of Dapsone at a dose of 100 mg per day was demonstrated by photographs.

  16. Portal annular pancreas: a systematic review of a clinical challenge.

    Science.gov (United States)

    Harnoss, Jonathan M; Harnoss, Julian C; Diener, Markus K; Contin, Pietro; Ulrich, Alexis B; Büchler, Markus W; Schmitz-Winnenthal, Friedrich H

    2014-10-01

    Portal annular pancreas (PAP) is an asymptomatic congenital pancreas anomaly, in which portal and/or mesenteric veins are encased by pancreas tissue. The aim of the study was to determine the role of PAP in pancreatic surgery as well as its management and potential complication, specifically, postoperative pancreatic fistula (POPF).On the basis of a case report, the MEDLINE and ISI Web of Science databases were systematically reviewed up to September 2012. All articles describing a case of PAP were considered.In summary, 21 studies with 59 cases were included. The overall prevalence of PAP was 2.4% and the patients' mean (SD) age was 55.9 (16.2) years. The POPF rate in patients with PAP (12 pancreaticoduodenectomies and 3 distal pancreatectomies) was 46.7% (in accordance with the definition of the International Study Group of Pancreatic Surgery).Portal annular pancreas is a quite unattended pancreatic variant with high prevalence and therefore still remains a clinical challenge to avoid postoperative complications. To decrease the risk for POPF, attentive preoperative diagnostics should also focus on PAP. In pancreaticoduodenectomy, a shift of the resection plane to the pancreas tail should be considered; in extensive pancreatectomy, coverage of the pancreatic remnant by the falciform ligament could be a treatment option.

  17. Core-annular flow through a horizontal pipe : Hydrodynamic counterbalancing of buoyancy force on core

    NARCIS (Netherlands)

    Ooms, G.; Vuik, C.; Poesio, P.

    2007-01-01

    A theoretical investigation has been made of core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe. Special attention is paid to the question of how the buoyancy force on the core, caused by a density difference

  18. Non-Newtonian fluid flow in annular pipes and entropy generation ...

    Indian Academy of Sciences (India)

    non-Newtonian parameter, while it is the reverse for the viscosity parame- ter, which is more pronounced in the region close to the annular pipe inner wall. Keywords. Non-Newtonian fluid; third-grade fluid; variable viscosity; entropy; entropy generation number. 1. Introduction. Flow through annular pipes finds application in ...

  19. Development of new correlations for annular flow; Desarrollo de Nuevas correlaciones para Flujo Anular

    Energy Technology Data Exchange (ETDEWEB)

    Escriva, A.; Munoz-Cobo, J. L.; Herranz, L. E.

    2013-07-01

    This paper explores the extensive literature and proposes new correlations for the study of annular flow. The interest of this paper is, first, in gathering the dispersed and abundant existing information and, secondly, to develop new correlations for the determination of the main quantities characterizing the annular flow from data experimental found in the open literature.

  20. Perspectives on wind shear flight

    Science.gov (United States)

    Miele, A.; Wang, T.; Wu, G. D.

    1991-01-01

    Wind shears originating from downbursts have been the cause of many aircraft accidents in the past two decades. In turn, this has led to considerable research on wind shear avoidance systems and wind shear recovery systems. This paper reviews recent advances in wind shear recovery systems. It summarizes the work done at Rice University on trajectory optimization and trajectory guidance for two basic flight conditions: takeoff and abort landing. It appears that, in the relatively near future, an advanced wind shear control system can be developed, that is, capable of functioning in different wind models and covering the spectrum of flight conditions having interest in a wind shear encounter.

  1. Annular core liquid-salt cooled reactor with multiple fuel and blanket zones

    Science.gov (United States)

    Peterson, Per F.

    2013-05-14

    A liquid fluoride salt cooled, high temperature reactor having a reactor vessel with a pebble-bed reactor core. The reactor core comprises a pebble injection inlet located at a bottom end of the reactor core and a pebble defueling outlet located at a top end of the reactor core, an inner reflector, outer reflector, and an annular pebble-bed region disposed in between the inner reflector and outer reflector. The annular pebble-bed region comprises an annular channel configured for receiving pebble fuel at the pebble injection inlet, the pebble fuel comprising a combination of seed and blanket pebbles having a density lower than the coolant such that the pebbles have positive buoyancy and migrate upward in said annular pebble-bed region toward the defueling outlet. The annular pebble-bed region comprises alternating radial layers of seed pebbles and blanket pebbles.

  2. Keyed shear joints

    DEFF Research Database (Denmark)

    Hansen, Klaus

    This report gives a summary of the present information on the behaviour of vertical keyed shear joints in large panel structures. An attemp is made to outline the implications which this information might have on the analysis and design of a complete wall. The publications also gives a short...

  3. Sheared solid materials

    Indian Academy of Sciences (India)

    However, if the shear modulus decreases with increasing , accumulation of around dislocation cores eventually breaks the Peierls potential leading to slow relaxations in the stress and the free energy (aging). As another application of our scheme, we also study dislocation formation in two-phase alloys (coherency loss) ...

  4. Sheared solid materials

    Indian Academy of Sciences (India)

    Abstract. We present a time-dependent Ginzburg–Landau model of nonlinear elasticity in solid materials. We assume that the elastic energy density is a periodic function of the shear and tetragonal strains owing to the underlying lattice structure. With this new ingredient, solving the equations yields formation of dislocation ...

  5. Revealing the frictional transition in shear-thickening suspensions

    Science.gov (United States)

    Clavaud, Cécile; Bérut, Antoine; Metzger, Bloen; Forterre, Yoël

    2017-05-01

    Shear thickening in dense particulate suspensions was recently proposed to be driven by the activation of friction above an onset stress needed to overcome repulsive forces between particles. Testing this scenario represents a major challenge because classical rheological approaches do not provide access to the frictional properties of suspensions. Here we adopt a different strategy inspired by pressure-imposed configurations in granular flows that specifically gives access to this information. By investigating the quasi-static avalanche angle, compaction, and dilatancy effects in different nonbuoyant suspensions flowing under gravity, we demonstrate that particles in shear-thickening suspensions are frictionless under low confining pressure. Moreover, we show that tuning the range of the repulsive force below the particle roughness suppresses the frictionless state and also the shear-thickening behavior of the suspension. These results, which link microscopic contact physics to the suspension macroscopic rheology, provide direct evidence that the recent frictional transition scenario applies in real suspensions.

  6. Shear strength of non-shear reinforced concrete elements

    DEFF Research Database (Denmark)

    Hoang, Cao linh

    1997-01-01

    The paper deals with the plastic shear strength of non shear reinforced T-beams.The influence of an un-reinforced flange on the shear capacity is investigated by considering a failure mechanism involving crack sliding in the web and a kind of membrane action over an effective width of the flange...

  7. Plasticity Approach to Shear Design

    DEFF Research Database (Denmark)

    Hoang, Cao Linh; Nielsen, Mogens Peter

    1998-01-01

    The paper presents some plastic models for shear design of reinforced concrete beams. Distinction is made between two shear failure modes, namely web crushing and crack sliding. The first mentioned mode is met in beams with large shear reinforcement degrees. The mode of crack sliding is met in non...... in uncracked concrete. Good agree between theory and tests has been found.Keywords: dsign, plasticity, reinforced concrete, reinforcement, shear, web crushing....

  8. Effects of Roughness and Inertia on Precursors to Frictional Sliding

    Science.gov (United States)

    Robbins, Mark O.; Salerno, K. Michael

    2012-02-01

    Experiments show that when a PMMA block on a surface is normally loaded and driven by an external shear force, contact at the interface is modified in discrete precursor slips prior to steady state sliding.[1] Our simulations use an atomistic model of a rough two-dimensional block in contact with a flat surface to investigate the evolution of stress and displacement along the contact between surfaces. The talk will show how local and global stress conditions govern the initiation of interfacial cracks as well as the spatial extension of the cracked region. Inertia also plays an important role in determining the number and size of slips before sliding and influences the distribution of stresses at the interface. Finally, the geometry of surface asperities also influences the interfacial evolution and the total friction force. The relationship between the interfacial stress state and rupture velocity will also be discussed. [1] S.M. Rubinstein, G. Cohen and J. Fineberg, PRL 98, 226103 (2007)

  9. Direct Shear Tests of Sandstone Under Constant Normal Tensile Stress Condition Using a Simple Auxiliary Device

    Science.gov (United States)

    Cen, Duofeng; Huang, Da

    2017-06-01

    Tension-shear failure is a typical failure mode in the rock masses in unloading zones induced by excavation or river incision, etc., such as in excavation-disturbed zone of deep underground caverns and superficial rocks of high steep slopes. However, almost all the current shear failure criteria for rock are usually derived on the basis of compression-shear failure. This paper proposes a simple device for use with a servo-controlled compression-shear testing machine to conduct the tension-shear tests of cuboid rock specimens, to test the direct shear behavior of sandstone under different constant normal tensile stress conditions ( σ = -1, -1.5, -2, -2.5 and -3 MPa) as well as the uniaxial tension behavior. Generally, the fracture surface roughness decreases and the proportion of comminution areas in fracture surface increases as the change of stress state from tension to tension-shear and to compression-shear. Stepped fracture is a primary fracture pattern in the tension-shear tests. The shear stiffness, shear deformation and normal deformation (except the normal deformation for σ = -1 MPa) decrease during shearing, while the total normal deformation containing the pre-shearing portion increases as the normal tensile stress level (| σ|) goes up. Shear strength is more sensitive to the normal tensile stress than to the normal compressive stress, and the power function failure criterion (or Mohr envelope form of Hoek-Brown criterion) is examined to be the optimal criterion for the tested sandstone in the full region of tested normal stress in this study.

  10. Subpatch roughness in earthquake rupture investigations

    National Research Council Canada - National Science Library

    Zielke, O; Mai, P. M

    2016-01-01

    ...) and strongly affect the rupture process at corresponding scales. Numerical rupture simulations provide a framework to quantitatively investigate the relationship between a fault's roughness and its seismic characteristics...

  11. Geometry-Driven Folding of a Floating Annular Sheet

    Science.gov (United States)

    Paulsen, Joseph D.; Démery, Vincent; Toga, K. Buǧra; Qiu, Zhanlong; Russell, Thomas P.; Davidovitch, Benny; Menon, Narayanan

    2017-01-01

    Predicting the large-amplitude deformations of thin elastic sheets is difficult due to the complications of self contact, geometric nonlinearities, and a multitude of low-lying energy states. We study a simple two-dimensional setting where an annular polymer sheet floating on an air-water interface is subjected to different tensions on the inner and outer rims. The sheet folds and wrinkles into many distinct morphologies that break axisymmetry. These states can be understood within a recent geometric approach for determining the gross shape of extremely bendable yet inextensible sheets by extremizing an appropriate area functional. Our analysis explains the remarkable feature that the observed buckling transitions between wrinkled and folded shapes are insensitive to the bending rigidity of the sheet.

  12. A Novel Design of Magnetorheological Damper with Annular Radial Channel

    Directory of Open Access Journals (Sweden)

    Shisha Zhu

    2016-01-01

    Full Text Available With the development of automotive vibration technology, the semiactive suspension system with adjustable damping force and high reliability is taken seriously. The magnetorheological damper (MRD that applies intelligent material (magnetorheological fluid is the key element of this system. It can achieve a continuous and adjustable damping and then reaches the purpose of comfort. In order to improve the damping effect of MRD, this paper presents a MRD, which has magnetorheological (MR effect along annular radial channel. The paper completely designs the structure and magnetic circuit of MRD. Based on the theory of electromagnetism and MR fluid dynamics, the paper analyzes and tests the external characteristics of the MRD by the MATLAB/Simulink and the vibration experiment. The results compared with ordinary MRD reveal that the damping force obviously increases and has wide adjustable range, thus verifying the reasonableness of the damper design.

  13. The theoretical model for the annular jet instability - Revisited

    Science.gov (United States)

    Lee, C. P.; Wang, T. G.

    1989-01-01

    The theoretical model of Lee and Wang (1986) for the instability of an annular jet, in which the jet's liquid layer is treated as a thin liquid sheet, is examined. It is suggested that the model should be altered so that when the envelope is closing its bottleneck during collapse, the new envelope experiences a sharp pressure pulse from its gaseous core, reversing the normal velocity of the sheet enough to maintain continuous constant gas flow. Using this improved version of the model, it is shown that if the liquid velocity is high enough and the gas velocity is greater than the liquid velocity, the bubble-formation frequency varies linearly with the difference between the two velocities, but not with their individual values.

  14. Flow instability and vortex street in eccentric annular channels

    Science.gov (United States)

    Choueiri, George; Tavoularis, Stavros

    2013-11-01

    Flow development in an eccentric annular channel with a diameter ratio of 0.5 has been investigated using flow visualization, two-component laser Doppler velocimetry and planar and stereoscopic particle image velocimetry. The eccentricity e was varied between 0.3 and 0.9 and the Reynolds number was 1000 flow instability and the generation of a quasi-periodic vortex street, which manifested itself by strong cross-flows across the gap and an increase in axial velocity in the gap region, but also affected the flow in the entire channel. The vortex strength was highest for e ~ 0 . 7 and the Strouhal number of the cross-flow oscillations (based on bulk velocity and core diameter) increased with increasing Re, reaching an asymptote near 0.12 for Re >= 10000 . Supported by NSERC and AECL.

  15. Annular elastolytic giant cell granuloma of conjunctiva: A case report

    Directory of Open Access Journals (Sweden)

    Karabi Konar

    2014-01-01

    Full Text Available Annular elastolytic giant cell granuloma is a condition characterized histologically by damaged elastic fibers associated with preponderance of giant cells along with absence of necrobiosis, lipid, mucin, and pallisading granuloma. It usually occurs on sun-damaged skin and hence the previous name actinic granuloma. A similar process occurs on the conjunctiva. Over the past three decades only four cases of conjunctival actinic granuloma have been documented. All the previous patients were females with lesions in nasal or temporal bulbar conjunctiva varying 2-3 mm in size. We report a male patient aged 70 years presenting with a 14 mm × 7 mm fleshy mass on right lower bulbar conjunctiva. Clinical differential diagnoses were lymphoma, squamous cell carcinoma in situ and amyloidosis. Surgical excision followed by histopathology confirmed it to be a case of actinic granuloma. This is the first case of isolated conjunctival actinic granuloma of such a large size reported from India.

  16. Annular suspension and pointing system with controlled DC electromagnets

    Science.gov (United States)

    Vu, Josephine Lynn; Tam, Kwok Hung

    1993-01-01

    The Annular Suspension and Pointing System (ASPS) developed by the Flight System division of Sperry Corporation is a six-degree of freedom payload pointing system designed for use with the space shuttle. This magnetic suspension and pointing system provides precise controlled pointing in six-degrees of freedom, isolation of payload-carrier disturbances, and end mount controlled pointing. Those are great advantages over the traditional mechanical joints for space applications. In this design, we first analyzed the assumed model of the single degree ASPS bearing actuator and obtained the plant dynamics equations. By linearizing the plant dynamics equations, we designed the cascade and feedback compensators such that a stable and satisfied result was obtained. The specified feedback compensator was computer simulated with the nonlinearized plant dynamics equations. The results indicated that an unstable output occurred. In other words, the designed feedback compensator failed. The failure of the design is due to the Taylor's series expansion not converging.

  17. Thirty Stage Annular Centrifugal Contactor Thermal Profile Measurements

    Energy Technology Data Exchange (ETDEWEB)

    David H. Meikrantz; Troy G. Garn; Jack D. Law

    2010-02-01

    A thirty stage 5 cm annular centrifugal contactor cascade has been assembled and tested to obtain thermal profiles during both ambient and heated input conditions of operation. Thermocouples were installed on every stage as well as feed inputs and Real-time data was taken during experiments lasting from two to eight hours at total flow rates of 0.5 to 1.4 liters per minute. Ambient temperature profile results show that only a small amount of heat is generated by the mechanical energy of the contactors. Steady state temperature profiles mimic the ambient temperature of the lab but are higher toward the middle of the cascade. Heated inlet solutions gave temperature profiles with smaller temperature gradients, more driven by the temperature of the inlet solutions than ambient lab temperature. Temperature effects of solution mixing, even at rotor speeds of 4000 rpm, were not measurable.

  18. Design of an Annular Disc Subject to Thermomechanical Loading

    Directory of Open Access Journals (Sweden)

    Sergei Alexandrov

    2012-01-01

    Full Text Available Two solutions to design a thin annular disc of variable thickness subject to thermomechanical loading are proposed. It is assumed that the thickness of the disc is everywhere sufficiently small for the stresses to be averaged through the thickness. The state of stress is plane. The initiation of plastic yielding is controlled by Mises yield criterion. The design criterion for one of the solutions proposed requires that the distribution of stresses is uniform over the entire disc. In this case there is a relation between optimal values of the loading parameters at the final stage. The specific shape of the disc corresponds to each pair of such parameters. The other solution is obtained under the additional requirement that the distribution of strains is uniform. This solution exists for the disc of constant thickness at specific values of the loading parameters.

  19. Shear Behavior of Concrete Beams Reinforced with GFRP Shear Reinforcement

    Directory of Open Access Journals (Sweden)

    Heecheul Kim

    2015-01-01

    Full Text Available This paper presents the shear capacities of concrete beams reinforced with glass fiber reinforced polymer (GFRP plates as shear reinforcement. To examine the shear performance, we manufactured and tested a total of eight specimens. Test variables included the GFRP strip-width-to-spacing ratio and type of opening array. The specimen with a GFRP plate with a 3×2 opening array showed the highest shear strength. From the test results, the shear strength increased as the strip-width-to-strip-spacing ratio increased. Also, we used the experimental results to evaluate whether the shear strength equations of ACI 318-14 and ACI 440.1R can be applied to the design of GFRP shear reinforcement. In the results, the ACI 440 equation underestimated the experimental results more than that of ACI 318.

  20. Shear Yielding and Shear Jamming of Dense Hard Sphere Glasses.

    Science.gov (United States)

    Urbani, Pierfrancesco; Zamponi, Francesco

    2017-01-20

    We investigate the response of dense hard sphere glasses to a shear strain in a wide range of pressures ranging from the glass transition to the infinite-pressure jamming point. The phase diagram in the density-shear strain plane is calculated analytically using the mean-field infinite-dimensional solution. We find that just above the glass transition, the glass generically yields at a finite shear strain. The yielding transition in the mean-field picture is a spinodal point in presence of disorder. At higher densities, instead, we find that the glass generically jams at a finite shear strain: the jamming transition prevents yielding. The shear yielding and shear jamming lines merge in a critical point, close to which the system yields at extremely large shear stress. Around this point, highly nontrivial yielding dynamics, characterized by system-spanning disordered fractures, is expected.

  1. Gelation under shear

    Energy Technology Data Exchange (ETDEWEB)

    Butler, B.D.; Hanley, H.J.M.; Straty, G.C. [National Institute of Standards and Technology, Boulder, CO (United States); Muzny, C.D. [Univ. of Colorado, Boulder, CO (United States)

    1995-12-31

    An experimental small angle neutron scattering (SANS) study of dense silica gels, prepared from suspensions of 24 nm colloidal silica particles at several volume fractions {theta} is discussed. Provided that {theta}{approx_lt}0.18, the scattered intensity at small wave vectors q increases as the gelation proceeds, and the structure factor S(q, t {yields} {infinity}) of the gel exhibits apparent power law behavior. Power law behavior is also observed, even for samples with {theta}>0.18, when the gel is formed under an applied shear. Shear also enhances the diffraction maximum corresponding to the inter-particle contact distance of the gel. Difficulties encountered when trying to interpret SANS data from these dense systems are outlined. Results of computer simulations intended to mimic gel formation, including computations of S(q, t), are discussed. Comments on a method to extract a fractal dimension characterizing the gel are included.

  2. An Optimization and Comparative Study of Air-Coupled CMUT Cells With Circular and Annular Geometries.

    Science.gov (United States)

    Na, Shuai; Li, Zhenhao; Wong, Lawrence L P; Chen, Albert I-Hsiang; Macecek, Mirek; Yeow, John T W

    2017-11-01

    Air-coupled capacitive micromachined ultrasonic transducers (CMUTs) with annular cell geometry have recently been reported to have a promising transmit sensitivity. This paper reports three optimization schemes, which further improve the transmit sensitivity and also help achieve a reasonable comparison between the novel annular and conventional circular cells. Lumped element models of both cell types with laminate plate structures are presented. Based on these models, a design optimization flowchart was constructed to facilitate analytical optimization on the three schemes. Circular and annular CMUTs with a common 97-kHz natural resonance frequency were fabricated and characterized to verify the efficacy of the optimization principle. Using the optimization flowchart, annular and circular cells with frequencies ranging from 100 to 300 kHz were analytically optimized and then compared. The comparison results demonstrate that, given the same dc bias and ac excitation voltage, the output power density at the plate surface of the optimized annular cell is double that of the optimized circular cell. Additionally, when generating the same surface power density, an optimized annular cell requires either half the dc bias or half the ac excitation voltage of an optimized circular cell. This paper provides a practical optimization framework for CMUT cell design and demonstrates the superiority of annular cells for air-coupled applications.

  3. Distinct annular oligomers captured along the assembly and disassembly pathways of transthyretin amyloid protofibrils.

    Directory of Open Access Journals (Sweden)

    Ricardo H Pires

    Full Text Available BACKGROUND: Defects in protein folding may lead to severe degenerative diseases characterized by the appearance of amyloid fibril deposits. Cytotoxicity in amyloidoses has been linked to poration of the cell membrane that may involve interactions with amyloid intermediates of annular shape. Although annular oligomers have been detected in many amyloidogenic systems, their universality, function and molecular mechanisms of appearance are debated. METHODOLOGY/PRINCIPAL FINDINGS: We investigated with high-resolution in situ atomic force microscopy the assembly and disassembly of transthyretin (TTR amyloid protofibrils formed of the native protein by pH shift. Annular oligomers were the first morphologically distinct intermediates observed in the TTR aggregation pathway. Morphological analysis suggests that they can assemble into a double-stack of octameric rings with a 16 ± 2 nm diameter, and displaying the tendency to form linear structures. According to light scattering data coupled to AFM imaging, annular oligomers appeared to undergo a collapse type of structural transition into spheroid oligomers containing 8-16 monomers. Disassembly of TTR amyloid protofibrils also resulted in the rapid appearance of annular oligomers but with a morphology quite distinct from that observed in the assembly pathway. CONCLUSIONS/SIGNIFICANCE: Our observations indicate that annular oligomers are key dynamic intermediates not only in the assembly but also in the disassembly of TTR protofibrils. The balance between annular and more compact forms of aggregation could be relevant for cytotoxicity in amyloidogenic disorders.

  4. Research on Annular Frictional Pressure Loss of Hydraulic-Fracturing in Buckling Coiled Tubing

    Science.gov (United States)

    Liu, Bin; Cai, Meng; Li, Junliang; Xu, Yongquan; Wang, Peng

    2018-01-01

    Compared with conventional hydraulic fracturing, coiled tubing (CT) annular delivery sand fracturing technology is a new method to enhance the recovery ratio of low permeability reservoir. Friction pressure loss through CT has been a concern in fracturing. The small diameter of CT limits the cross-sectional area open to flow, therefore, to meet large discharge capacity, annular delivery sand technology has been gradually developed in oilfield. Friction pressure is useful for determining the required pump horsepower and fracturing construction design programs. Coiled tubing can buckle when the axial compressive load acting on the tubing is greater than critical buckling load, then the geometry shape of annular will change. Annular friction pressure loss elevates dramatically with increasing of discharge capacity, especially eccentricity and CT buckling. Despite the frequency occurrence of CT buckling in oilfield operations, traditionally annular flow frictional pressure loss considered concentric and eccentric annuli, not discussing the effects of for discharge capacity and sand ratio varying degree of CT buckling. The measured data shows that the factors mentioned above cannot be ignored in the prediction of annular pressure loss. It is necessary to carry out analysis of annulus flow pressure drop loss in coiled tubing annular with the methods of theoretical analysis and numerical simulation. Coiled tubing buckling has great influence on pressure loss of fracturing fluid. Therefore, the correlations have been developed for turbulent flow of Newtonian fluids and Two-phase flow (sand-liquid), and that improve the friction pressure loss estimation in coiled tubing operations involving a considerable level of buckling. Quartz sand evidently increases pressure loss in buckling annular, rising as high as 40%-60% more than fresh water. Meanwhile, annulus flow wetted perimeter increases with decreasing helical buckling pitch of coiled tubing, therefore, the annulus flow

  5. An annular gap acceleration model for $\\gamma$-ray emission of pulsars

    OpenAIRE

    Qiao, G. J.; Lee, K. J.; B. Zhang; Wang, H. G.; Xu, R. X.

    2007-01-01

    If the binding energy of the pulsar's surface is not so high (the case of a neutron star), both the negative and positive charges will flow out freely from the surface of the star. The annular free flow model for $\\gamma$-ray emission of pulsars is suggested in this paper. It is emphasized that: (1). Two kinds of acceleration regions (annular and core) need to be taken into account. The annular acceleration region is defined by the magnetic field lines that cross the null charge surface withi...

  6. A RARE CASE OF UNILATERAL ANNULAR SCLERITIS PROGRESSING TO SCLERA – KERATO - UVEITIS

    Directory of Open Access Journals (Sweden)

    Padmini

    2016-02-01

    Full Text Available INTRODUCTION We agree to the fact that ocular trauma may lead to non-infectious uveitis with scleritis. Here, we report the case of a patient who developed unilateral annular scleritis as the complication of anterior scleritis following ocular trauma. The causes of inflammation including Infection and systemic inflammatory diseases were excluded. Hence, our findings suggest that ocular trauma may act as a trigger for scleritis. Annular scleritis is defined as a circum-corneal gelatinous brawny infiltration accompanying the sclerosing keratitis. This rare entity occurs usually after the age of sixty. The case here described was unilateral annular sclera-kerato-uveitis leading to diffuse scleritis.

  7. A woman with juxta-articular nodules—An uncommon form of subcutaneous granuloma annulare

    Directory of Open Access Journals (Sweden)

    Lili Wang

    2014-06-01

    Full Text Available Granuloma annulare is a benign inflammatory dermatosis that is most common in children and young adults. The subcutaneous form of granuloma annulare, which occurs mainly on the extremities in children, is rare. Lesions usually occur as painless subcutaneous nodules without inflammation of the cutaneous surface; the most frequent sites are the legs, buttocks, and scalp. Nevertheless, we present a case of subcutaneous granuloma annulare confined to the dorsa of the hand joints and right knee in a 51-year-old woman.

  8. Specular Reflection from Rough Surfaces Revisited

    Science.gov (United States)

    Yasuda, Kensei; Kim, Alvin; Cho, Hayley; Timofejev, Timofej; Walecki, Wojciech J.; Klep, James; Edelson, Amy S.; Walecki, Abigail S.; Walecki, Eve S.; Walecki, Peter S.

    2016-01-01

    In his beautiful paper, Hasan Fakhruddin reported observations of mirror-like reflections in the rough surface of a ground glass plate. Similar effects have been recently employed for metrology of the roughness of optical diffusers used in modern light emitting device illumination systems. We report the observations of specular reflection in…

  9. Roughness on Dutch railway wheels and rails

    NARCIS (Netherlands)

    Dings, P.C.; Dittrich, M.G.

    1996-01-01

    Surface roughness on 150 railway wheels and on the rails of 30 sites in the Netherlands have been measured. Block braked wheels were found to show higher roughnesses than the rail at any site. The smoothest rail is 8 dB smoother than the smoothest wheel. It was concluded that in reducing railway

  10. Axiomatic Characterizations of IVF Rough Approximation Operators

    OpenAIRE

    Yu, Guangji

    2014-01-01

    This paper is devoted to the study of axiomatic characterizations of IVF rough approximation operators. IVF approximation spaces are investigated. The fact that different IVF operators satisfy some axioms to guarantee the existence of different types of IVF relations which produce the same operators is proved and then IVF rough approximation operators are characterized by axioms.

  11. Axiomatic Characterizations of IVF Rough Approximation Operators

    Directory of Open Access Journals (Sweden)

    Guangji Yu

    2014-01-01

    Full Text Available This paper is devoted to the study of axiomatic characterizations of IVF rough approximation operators. IVF approximation spaces are investigated. The fact that different IVF operators satisfy some axioms to guarantee the existence of different types of IVF relations which produce the same operators is proved and then IVF rough approximation operators are characterized by axioms.

  12. Bed roughness experiments in supply limited conditions

    NARCIS (Netherlands)

    Spekkers, Matthieu; Tuijnder, Arjan; Ribberink, Jan S.; Hulscher, Suzanne J.M.H.; Parsons, D.R.; Garlan, T.; Best, J.L.

    2008-01-01

    Reliable roughness models are of great importance, for example, when predicting water levels in rivers. The currently available roughness models are based on fully mobile bed conditions. However, in rivers where widely graded sediments are present more or less permanent armour layers can develop

  13. Turning rough sleepers into responsible citizens

    NARCIS (Netherlands)

    E. Tonkens; dr Lia van Doorn

    2001-01-01

    On the eve of the twenty-first century, it is a scandal that there are still people sleeping rough on our streets. This is not a situation we can continue to tolerate in a modern and civil society. These were the words of Tony Blair in his foreword to the policy document Rough Sleeping, The

  14. Computation of surface roughness using optical correlation

    Indian Academy of Sciences (India)

    The laser speckle photography is used to calculate the average surface rough- ness from the autocorrelation function of the aluminum diffuse objects. The computed results of surface roughness obtained from the profile shapes of the autocorrelation func- tion of the diffuser show good agreement with the results obtained by ...

  15. Electrochemically grown rough-textured nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, Pawan; Postetter, David; Saragnese, Daniel [Johns Hopkins University, Department of Chemical and Biomolecular Engineering (United States); Papadakis, Stergios J. [Johns Hopkins University, Applied Physics Laboratory (United States); Gracias, David H., E-mail: dgracias@jhu.ed [Johns Hopkins University, Department of Chemical and Biomolecular Engineering (United States)

    2010-03-15

    Nanowires with a rough surface texture show unusual electronic, optical, and chemical properties; however, there are only a few existing methods for producing these nanowires. Here, we describe two methods for growing both free standing and lithographically patterned gold (Au) nanowires with a rough surface texture. The first strategy is based on the deposition of nanowires from a silver (Ag)-Au plating solution mixture that precipitates an Ag-Au cyanide complex during electrodeposition at low current densities. This complex disperses in the plating solution, thereby altering the nanowire growth to yield a rough surface texture. These nanowires are mass produced in alumina membranes. The second strategy produces long and rough Au nanowires on lithographically patternable nickel edge templates with corrugations formed by partial etching. These rough nanowires can be easily arrayed and integrated with microscale devices.

  16. In-plane Shear Joint Capacity of Pracast Lightweight Aggregate Concrete Elements

    DEFF Research Database (Denmark)

    Larsen, Henning; Goltermann, Per; Scherfig, Søren

    1996-01-01

    The paper establishes and documents formulas for the in-plane shear capacity between precast elements of lightweight aggregate concrete with open structure. The joints investigated are rough or toothed and have all been precracked prior to the testing in order to obtain realistic test results...

  17. Flow Characteristics and Sizing of Annular Seat Valves for Digital Displacement Machines

    DEFF Research Database (Denmark)

    Nørgård, Christian; Bech, Michael Møller; Andersen, Torben O.

    2018-01-01

    This paper investigates the steady-state flow characteristics and power losses of annular seat valves for digital displacement machines. Annular seat valves are promising candidates for active check-valves used in digital displacement fluid power machinery which excels in efficiency in a broad...... operating range. To achieve high machine efficiency, the valve flow losses and the required electrical power needed for valve switching should be low. The annular valve plunger geometry, of a valve prototype developed for digital displacement machines, is parametrized by three parameters: stroke length...... a valve prototype. Using the simulated maps to estimate the flow power losses and a simple generic model to estimate the electric power losses, both during digital displacement operation, optimal designs of annular seat valves, with respect to valve power losses, are derived under several different...

  18. Effect of January 15, 2010 annular solar eclipse on meteorological parameters over Goa, India

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; Nisha, P.G.; Mohankumar, K.

    Atmospheric perturbations due to the annular solar eclipse were monitored to understand its influence on the meteorological parameters from surface to the lower stratosphere. A strong inversion at 13 km and an abnormal warming in the upper...

  19. Particle acceleration in the core and annular regions of pulsar magnetospheres

    Science.gov (United States)

    Lee, K.; Qiao, G.; Xu, R.

    It is realized recently that the high altitude acceleration are very important for the gamma -ray radiation from pulsars Qiao et al 2004 Dyks and Rudak 2003 There is already some work on the physical foundation of this high altitude acceleration Muslimov and Harding 2004 In this presentation we will demonstrate that the open magnetic field line region should be separated into two parts the annular and the core regions It will be shown that the annular region is important for the high altitude acceleration It is found that the annular cap region is an important plasma source and the secondary pairs can gain higher acceleration within the annular region This offers physical foundations for the geometrical gamma -ray radiative models Qiao et al 2004 Dyks and Rudak 2003

  20. Maximizing prosthetic valve size with the Top Hat supra-annular aortic valve

    DEFF Research Database (Denmark)

    Aagaard, Jan; Geha, Alexander S.

    2007-01-01

    -annular mechanical prostheses (CarboMedics, Inc., Arvada, CO, USA) at two institutions. Size frequency distribution was compared to published series, and to the manufacturer's US registry. The ventriculoaortic junction (VAJ) size was available in 234 patients, and compared to the size of the Top Hat valve implanted......BACKGROUND AND AIM OF THE STUDY: The CarboMedics Top Hat supra-annular aortic valve allows a one-size (and often two-size) increase over the standard intra-annular valve. This advantage should minimize the risk of patient-prosthesis mismatch, where the effective prosthetic valve orifice area...... is less than that of a normal valve. It is suggested that the ability to implant Top Hat valves having greater size, relative to standard intra-annular valves, may currently be under-utilized. Further, there has been some concern that Top Hat implantation can cause obstruction of the coronary ostia...

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

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Pei-Yang [Intel Corp., Santa Clara, CA (United States); Zhang, Guojing [Intel Corp., Santa Clara, CA (United States); Gullickson, Eric M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Goldberg, Kenneth A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Benk, Markus P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-03-01

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

  2. Numerical Simulation of Non-Newtonian Core Annular Flow through Rectangle Return Bends

    OpenAIRE

    Fan Jiang; Yun Long; Yijun Wang; Zhenzhang Liu; Conggui Chen

    2016-01-01

    The volume of fluid (VOF) model together with the continuum surface stress (CSS) model is proposed to simulate the core annular of non-Newtonian oil and water flow through the rectangle return bends (∏-bends). A comprehensive investigation is conducted to generate the profiles of volume fraction, pressure and velocity. The influences of oil properties, flow direction, and bend geometric parameters on hydrodynamic of nonNewtonian oil and water core annular flow in ∏-bends are discusse...

  3. A comparison between numerical predictions and theoretical and experimental results for laminar core-annular flow

    OpenAIRE

    Beerens, J.C.; Ooms, G.; Pourquie, M.J.B.M.; Westerweel, J.

    2014-01-01

    high-viscosity liquid core surrounded by a laminar low-viscosity liquid annular layer through a vertical pipe. The numerical results are compared with theoretical results from linear stability calculations and with experimental data. The comparison is good and the general conclusion of our study is that it is very well possible to simulate laminar core-annular flow in a pipe using the volume-of-fluid method.

  4. Remission of generalized erythematous granuloma annulare after improvement of hyperlipidemia and review of the Japanese literature

    OpenAIRE

    Watanabe, Soko; Tanaka, Masaru; Kobayashi, Ken; Sawada, Mizuki; Ishizaki, Sumiko; Tsurui, Koji; Fujibayashi, Mariko

    2014-01-01

    Granuloma annulare has been associated with systemic disease including diabetes mellitus. We report a case of a 62-year-old Japanese woman with generalized erythematous granuloma annulare who showed remission after substantial improvement in hyperlipidemia following a strict lipid-lowering diet. The lesion appeared in the lower abdomen one year before current presentation and subsequently spread to other areas of the trunk despite treatment with topical steroid and oral epinastine hydrochlori...

  5. Modified Surgical Intervention for Extensive Mitral Valve Endocarditis and Posterior Mitral Annular Calcification

    Directory of Open Access Journals (Sweden)

    Gwan Sic Kim

    2016-02-01

    Full Text Available The concomitant presence of posterior mitral annular calcification and infectious mitral valve lesions poses a technical challenge with considerable perioperative risk when using previously proposed techniques for mitral valve surgery. Herein, we report a case of the use of a modified surgical technique to successfully treat a patient with mitral infective endocarditis complicated by a subendocardial abscess and extensive posterior mitral annular calcification.

  6. The influence of the equivalent hydraulic diameter on the pressure drop prediction of annular test section

    Science.gov (United States)

    Al-Kayiem, A. H. H.; Ibrahim, M. A.

    2015-12-01

    The flow behaviour and the pressure drop throughout an annular flow test section was investigated in order to evaluate and justify the reliability of experimental flow loop for wax deposition studies. The specific objective of the present paper is to assess and highlight the influence of the equivalent diameter method on the analysis of the hydrodynamic behaviour of the flow and the pressure drop throughout the annular test section. The test section has annular shape of 3 m length with three flow passages, namely; outer thermal control jacket, oil annular flow and inner pipe flow of a coolant. The oil annular flow has internal and external diameters of 0.0422 m and 0.0801 m, respectively. Oil was re-circulated in the annular passage while a cold water-glycol mixture was re-circulated in the inner pipe counter currently to the oil flow. The experiments were carried out at oil Reynolds number range of 2000 to 17000, covering laminar, transition and turbulent flow regimes. Four different methods of equivalent diameter of the annulus have been considered in this hydraulic analysis. The correction factor model for frictional pressure drop was also considered in the investigations. All methods addressed the high deviation of the prediction from the experimental data, which justified the need of a suitable pressure prediction correlation for the annular test section. The conventional hydraulic diameter method is a convenient substitute for characterizing physical dimension of a non-circular duct, and it leads to fairly good correlation between turbulent fluid flow and heat transfer characteristic of annular ducts.

  7. Effect of pulse pressure on borehole stability during shear swirling flow vibration cementing

    Science.gov (United States)

    2017-01-01

    The shear swirling flow vibration cementing (SSFVC) technique rotates the downhole eccentric cascade by circulating cementing fluid. It makes the casing eccentrically revolve at high speed around the borehole axis. It produces strong agitation action to the annulus fluid, makes it in the state of shear turbulent flow, and results in the formation of pulse pressure which affects the surrounding rock stress. This study was focused on 1) the calculation of the pulse pressure in an annular turbulent flow field based on the finite volume method, and 2) the analysis of the effect of pulse pressure on borehole stability. On the upside, the pulse pressure is conducive to enhancing the liquidity of the annulus fluid, reducing the fluid gel strength, and preventing the formation of fluid from channeling. But greater pulse pressure may cause lost circulation and even formation fracturing. Therefore, in order to ensure smooth cementing during SSFVC, the effect of pulse pressure should be considered when cementing design. PMID:29145408

  8. Effect of pulse pressure on borehole stability during shear swirling flow vibration cementing.

    Directory of Open Access Journals (Sweden)

    Zhihua Cui

    Full Text Available The shear swirling flow vibration cementing (SSFVC technique rotates the downhole eccentric cascade by circulating cementing fluid. It makes the casing eccentrically revolve at high speed around the borehole axis. It produces strong agitation action to the annulus fluid, makes it in the state of shear turbulent flow, and results in the formation of pulse pressure which affects the surrounding rock stress. This study was focused on 1 the calculation of the pulse pressure in an annular turbulent flow field based on the finite volume method, and 2 the analysis of the effect of pulse pressure on borehole stability. On the upside, the pulse pressure is conducive to enhancing the liquidity of the annulus fluid, reducing the fluid gel strength, and preventing the formation of fluid from channeling. But greater pulse pressure may cause lost circulation and even formation fracturing. Therefore, in order to ensure smooth cementing during SSFVC, the effect of pulse pressure should be considered when cementing design.

  9. Ulcerative dermatosis of the Shetland sheepdog and rough collie dog may represent a novel vesicular variant of cutaneous lupus erythematosus.

    Science.gov (United States)

    Jackson, H A; Olivry, T

    2001-02-01

    A syndrome of ulcerative dermatitis (UDSSC) previously has been described as unique to the Shetland sheepdog and rough collie dog. The pathogenesis of this disease is poorly understood and it has been suggested that it may be a variant of canine dermatomyositis (DM) which is also seen in these breeds. Information on the clinical presentation and previous medical history was collected from five Shetland sheepdogs and three rough collie dogs previously diagnosed with UDSSC. Characteristic features of the disease were adult onset in the summer months with annular, polycyclic and serpiginous ulcerations distributed over sparsely haired areas of the body. Skin biopsies taken from active lesions were compared in a blinded fashion with histological sections from seven Shetland sheepdogs and one rough collie with DM. Dermatomyositis was characterized histologically as a cell poor interface dermatitis associated with follicular atrophy. In contrast, the lesional pattern of UDSSC is that of a lymphocyte-rich interface dermatitis and folliculitis with vesiculation at the dermal-epidermal junction. The authors conclude that these represent two distinct diseases and that UDSSC may be a vesicular form of cutaneous lupus erythematosus seen in the adult rough collie dog and Shetland sheepdog.

  10. Fluid-Structure Interaction Analysis on Turbulent Annular Seals of Centrifugal Pumps during Transient Process

    Directory of Open Access Journals (Sweden)

    Qinglei Jiang

    2011-01-01

    Full Text Available The current paper studies the influence of annular seal flow on the transient response of centrifugal pump rotors during the start-up period. A single rotor system and three states of annular seal flow were modeled. These models were solved using numerical integration and finite difference methods. A fluid-structure interaction method was developed. In each time step one of the three annular seal models was chosen to simulate the annular seal flow according to the state of rotor systems. The objective was to obtain a transient response of rotor systems under the influence of fluid-induced forces generated by annular seal flow. This method overcomes some shortcomings of the traditional FSI method by improving the data transfer process between two domains. Calculated results were in good agreement with the experimental results. The annular seal was shown to have a supportive effect on rotor systems. Furthermore, decreasing the seal clearance would enhance this supportive effect. In the transient process, vibration amplitude and critical speed largely changed when the acceleration of the rotor system increased.

  11. Burnable Absorber-Filled Annular UO{sub 2} Fuels for PWR

    Energy Technology Data Exchange (ETDEWEB)

    Yahya, Mohd-Syukri; Kim, Yonghee [KAIST, Daejeon (Korea, Republic of); Chung, ChangKyu [KEPCO EnC, Daejeon (Korea, Republic of)

    2015-10-15

    Its central annulus hole also provides an additional plenum for the fission gas release. In fact, annular UO{sub 2} fuels have successfully been used in commercial Russian's nuclear reactors for decades. It was upon this notion that a study was recently performed to re-investigate neutronic characteristics of the annular fuel in a rod-cell lattice. The said study also proposed an innovative integral burnable absorber (BA) concept by loading of a porous BA rod inside central hole of the annular fuel. This current work aims to extend the said investigation by characterizing neutronic performances of the BA-filled annular fuels in standard PWR 17x17 and 16x16 fuel assembly lattices. Preliminary results suggested promising potentials of the novel BA concept in managing the assembly lattice reactivity and power peaking. All calculations were performed using the Monte Carlo Serpent code with ENDF/B7.0 library. This paper demonstrates neutronic feasibilities of the BA-filled annular fuels in standard PWR 17x17 and 16x16 fuel assembly lattices. One notes that the BA-filled annular fuel-loaded lattice display comparable neutronic characteristics to the benchmarked commercial BA designs, especially in terms of reactivity and peaking factor management.

  12. Hydrodynamics in a circulating fluidized bed with annular furnace and six parallel cyclones

    Science.gov (United States)

    Shuai, Daping; Wang, Xiaofang; Lyu, Qinggang

    2017-06-01

    Systematic measurements were conducted on a cold CFB with annular furnace and six parallel cyclones to study gas-solids flow in the annular furnace and flow non-uniformity among six cyclones. The results show that axial solids holdup in the annular furnace decreases exponentially with height, similar to the conventional rectangular furnace. The uniform transverse distribution of solids holdup suggests a good gas-solids mixing in the annular furnace. The annular furnace presents the core/double-annulus flow structure, and it results in enhanced gas-solids back-mixing than the conventional core/annulus flow structure. The gas-solids flow of the inner wall-layer and the outer wall-layer is very close at most part of the furnace height, and the wall-layer thickness decreases with height. Flow non-uniformity exists among six parallel cyclones in the annular furnace CFB. But non-uniform distribution of solids circulating rates and cyclone pressure drops show no regularity, and the flow non-uniformity is no larger than the CFBs with conventional furnace. Under typical operating conditions, the relative deviation of six solids circulating rates is 8.0%.

  13. Monthly rifampicin, ofloxacin, and minocycline therapy for generalized and localized granuloma annulare

    Directory of Open Access Journals (Sweden)

    Shilpa Garg

    2015-01-01

    Full Text Available Background: The localized form of granuloma annulare is usually self-limiting, resolving within 2 years. Generalized granuloma annulare, on the other hand, runs a protracted course, with spontaneous resolution being rare. It is also characterized by a later age of onset, an increased incidence of diabetes mellitus, poor response to therapy, and an increased prevalence of HLA Bw35. Objective: To assess the efficacy of monthly pulsed rifampicin, ofloxacin, and minocycline (ROM therapy in the management of granuloma annulare. Methods : Six biopsy proven patients of granuloma annulare were included in the study, five of the generalized variety, and one localized. Three of these patients were resistant to standard modalities of treatment. All six patients were treated with pulses of once monthly ROM till complete resolution of all lesions. Results were analyzed in terms of complete resolution of lesions and side effects. Presence of comorbid conditions was noted. Result: All six patients were successfully treated with 4-8 pulses of monthly ROM. None of the patients reported any adverse effects. Limitations: Small sample size and the lack of a control group are limitations. Conclusion: Treatment with pulses of once monthly ROM caused complete resolution of lesions in both localized and generalized granuloma annulare, even in cases recalcitrant to conventional therapy. There were no side effects in any of the patients. Larger trials are needed to substantiate the efficacy of monthly ROM in granuloma annulare.

  14. Annular Air Leaks in a liquid hydrogen storage tank

    Science.gov (United States)

    Krenn, AG; Youngquist, RC; Starr, SO

    2017-12-01

    Large liquid hydrogen (LH2) storage tanks are vital infrastructure for NASA, the DOD, and industrial users. Over time, air may leak into the evacuated, perlite filled annular region of these tanks. Once inside, the extremely low temperatures will cause most of the air to freeze. If a significant mass of air is allowed to accumulate, severe damage can result from nominal draining operations. Collection of liquid air on the outer shell may chill it below its ductility range, resulting in fracture. Testing and analysis to quantify the thermal conductivity of perlite that has nitrogen frozen into its interstitial spaces and to determine the void fraction of frozen nitrogen within a perlite/frozen nitrogen mixture is presented. General equations to evaluate methods for removing frozen air, while avoiding fracture, are developed. A hypothetical leak is imposed on an existing tank geometry and a full analysis of that leak is detailed. This analysis includes a thermal model of the tank and a time-to-failure calculation. Approaches to safely remove the frozen air are analyzed, leading to the conclusion that the most feasible approach is to allow the frozen air to melt and to use a water stream to prevent the outer shell from chilling.

  15. HAMLET forms annular oligomers when deposited with phospholipid monolayers.

    Science.gov (United States)

    Baumann, Anne; Gjerde, Anja Underhaug; Ying, Ming; Svanborg, Catharina; Holmsen, Holm; Glomm, Wilhelm R; Martinez, Aurora; Halskau, Oyvind

    2012-04-20

    Recently, the anticancer activity of human α-lactalbumin made lethal to tumor cells (HAMLET) has been linked to its increased membrane affinity in vitro, at neutral pH, and ability to cause leakage relative to the inactive native bovine α-lactalbumin (BLA) protein. In this study, atomic force microscopy resolved membrane distortions and annular oligomers (AOs) produced by HAMLET when deposited at neutral pH on mica together with a negatively charged lipid monolayer. BLA, BAMLET (HAMLET's bovine counterpart) and membrane-binding Peptide C, corresponding to BLA residues 75-100, also form AO-like structures under these conditions but at higher subphase concentrations than HAMLET. The N-terminal Peptide A, which binds to membranes at acidic but not at neutral pH, did not form AOs. This suggests a correlation between the capacity of the proteins/peptides to integrate into the membrane at neutral pH-as observed by liposome content leakage and circular dichroism experiments-and the formation of AOs, albeit at higher concentrations. Formation of AOs, which might be important to HAMLET's tumor toxic action, appears related to the increased tendency of the protein to populate intermediately folded states compared to the native protein, the formation of which is promoted by, but not uniquely dependent on, the oleic acid molecules associated with HAMLET. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Numerical Study of Transition of an Annular Lift Fan Aircraft

    Directory of Open Access Journals (Sweden)

    Yun Jiang

    2016-09-01

    Full Text Available The present study aimed at studying the transition of annular lift fan aircraft through computational fluid dynamics (CFD simulations. The oscillations of lift and drag, the optimization for the figure of merit, and the characteristics of drag, yawing, rolling and pitching moments in transition are studied. The results show that a two-stage upper and lower fan lift system can generate oscillations of lift and drag in transition, while a single-stage inner and outer fan lift system can eliminate the oscillations. The characteristics of momentum drag of the single-stage fans in transition are similar to that of the two-stage fans, but with the peak of drag lowered from 0.63 to 0.4 of the aircraft weight. The strategy to start transition from a negative angle of attack −21° further reduces the peak of drag to 0.29 of the weight. The strategy also reduces the peak of pitching torque, which needs upward extra thrusts of 0.39 of the weight to eliminate. The peak of rolling moment in transition needs differential upward thrusts of 0.04 of the weight to eliminate. The requirements for extra thrusts in transition lead to a total thrust–weight ratio of 0.7, which makes the aircraft more efficient for high speed cruise flight (higher than 0.7 Ma.

  17. Current Density Measurements of an Annular-Geometry Ion Engine

    Science.gov (United States)

    Shastry, Rohit; Patterson, Michael J.; Herman, Daniel A.; Foster, John E.

    2012-01-01

    The concept of the annular-geometry ion engine, or AGI-Engine, has been shown to have many potential benefits when scaling electric propulsion technologies to higher power. However, the necessary asymmetric location of the discharge cathode away from thruster centerline could potentially lead to non-uniformities in the discharge not present in conventional geometry ion thrusters. In an effort to characterize the degree of this potential non-uniformity, a number of current density measurements were taken on a breadboard AGI-Engine. Fourteen button probes were used to measure the ion current density of the discharge along a perforated electrode that replaced the ion optics during conditions of simulated beam extraction. Three Faraday probes spaced apart in the vertical direction were also used in a separate test to interrogate the plume of the AGI-Engine during true beam extraction. It was determined that both the discharge and the plume of the AGI-Engine are highly uniform, with variations under most conditions limited to +/-10% of the average current density in the discharge and +/-5% of the average current density in the plume. Beam flatness parameter measured 30 mm from the ion optics ranged from 0.85 - 0.95, and overall uniformity was shown to generally increase with increasing discharge and beam currents. These measurements indicate that the plasma is highly uniform despite the asymmetric location of the discharge cathode.

  18. An Unusual Presentation of Annular Pancreas: A Case Report

    Directory of Open Access Journals (Sweden)

    Saleheh Ala

    2015-01-01

    Full Text Available Abstract Annular pancreas (AP is a rare congenital malformation resulting from failure of pancreas ventral anlage rotation with the duodenum. This leads to a ring of pancreatic tissue that envelops the duodenum. Clinical manifestations of AP most commonly develop in infancy or early childhood but can present at any age. The diagnosis of AP, usually suggested by an upper GI series or abdominal CT scan, but surgery is considered the gold standard diagnostic method. Surgical bypass of the annulus in all patients with symptomatic AP is recommended. We report a one year old girl who presented with intermittent, non projectile, non bilious vomiting that occurred 1h to 2h after feeding since neonatal period. Upper GI contrast study demonstrates, a dilated duodenal bulb associated with narrowing of post bulbar area. The patient underwent surgical correction of the obstruction. A bypass of the ectopic pancreas tissue was performed by duodenoduodenostomy. Considering the rarity of this congenital abnormality, presenting with chronic partial duodenal obstruction, and its successful correction by surgical means have prompted us to report the case.

  19. Development of sol-gel icephobic coatings: effect of surface roughness and surface energy.

    Science.gov (United States)

    Fu, Qitao; Wu, Xinghua; Kumar, Divya; Ho, Jeffrey W C; Kanhere, Pushkar D; Srikanth, Narasimalu; Liu, Erjia; Wilson, Peter; Chen, Zhong

    2014-12-10

    Sol-gel coatings with different roughness and surface energy were prepared on glass substrates. Methyl triethoxysilane (MTEOS), 3-Glycidyloxypropyl trimethoxysilane (GLYMO) and fluoroalkylsilane (FAS) were used to obtain a mechanically robust icephobic coating. Different amount of hydrophobic silica nano particles was added as fillers to introduce different roughness and surface energy to the coatings. The microstructure, roughness, and surface energy, together with elemental information and surface chemical state, were investigated at room temperature. The contact angle and sliding angle were measured at different temperatures to correlate the wetting behavior at low temperature with the anti-icing performance. The ice adhesion shear strength was measured inside an ice chamber using a self-designed tester. The factors influencing the ice adhesion were discussed, and the optimum anti-icing performance found in the series of coatings. It was found that lower surface energy leads to lower ice adhesion regardless of the roughness, while the roughness plays a more complicated role. The wetting behavior of the droplet on surface changes as temperature decreases. The anti-icing performance is closely related to the antiwetting property of the surfaces at subzero temperatures.

  20. Shear strength of non-shear reinforced concrete elements

    DEFF Research Database (Denmark)

    Hoang, Cao linh

    1997-01-01

    The paper deals with the shear strength of prestressed hollow-core slabs determined by the theory of plasticity. Two failure mechanisms are considered in order to derive the solutions.In the case of sliding failure in a diagonal crack, the shear strength is determined by means of the crack sliding...

  1. Shear strength of non-shear reinforced concrete elements

    DEFF Research Database (Denmark)

    Hoang, Cao linh

    1997-01-01

    The report deals with the shear strength of statically indeterminate reinforced concrete beams without shear reinforcement. Solutions for a number of beams with different load and support conditions have been derived by means of the crack sliding model developed by Jin- Ping Zhang.This model...

  2. McNary - Rough Fish Control

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of the action is to enhance environmental conditions in the McNary Slough by reducing the population of rough fish, including common carp (Cyprinus...

  3. SMEX03 Surface Roughness Data, Alabama

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set SMEX03 Surface Roughness Data is comprised of data collected over the regional study areas of Alabama, Georgia, and Oklahoma, USA as part of the 2003...

  4. Three-tier rough superhydrophobic surfaces.

    Science.gov (United States)

    Cao, Yuanzhi; Yuan, Longyan; Hu, Bin; Zhou, Jun

    2015-08-07

    A three-tier rough superhydrophobic surface was fabricated by growing hydrophobic modified (fluorinated silane) zinc oxide (ZnO)/copper oxide (CuO) hetero-hierarchical structures on silicon (Si) micro-pillar arrays. Compared with the other three control samples with a less rough tier, the three-tier surface exhibits the best water repellency with the largest contact angle 161° and the lowest sliding angle 0.5°. It also shows a robust Cassie state which enables the water to flow with a speed over 2 m s(-1). In addition, it could prevent itself from being wetted by the droplet with low surface tension (mixed water and ethanol 1:1 in volume) which reveals a flow speed of 0.6 m s(-1) (dropped from the height of 2 cm). All these features prove that adding another rough tier on a two-tier rough surface could futher improve its water-repellent properties.

  5. Prediction of static friction coefficient in rough contacts based on the junction growth theory

    Science.gov (United States)

    Spinu, S.; Cerlinca, D.

    2017-08-01

    The classic approach to the slip-stick contact is based on the framework advanced by Mindlin, in which localized slip occurs on the contact area when the local shear traction exceeds the product between the local pressure and the static friction coefficient. This assumption may be too conservative in the case of high tractions arising at the asperities tips in the contact of rough surfaces, because the shear traction may be allowed to exceed the shear strength of the softer material. Consequently, the classic frictional contact model is modified in this paper so that gross sliding occurs when the junctions formed between all contacting asperities are independently sheared. In this framework, when the contact tractions, normal and shear, exceed the hardness of the softer material on the entire contact area, the material of the asperities yields and the junction growth process ends in all contact regions, leading to gross sliding inception. This friction mechanism is implemented in a previously proposed numerical model for the Cattaneo-Mindlin slip-stick contact problem, which is modified to accommodate the junction growth theory. The frictionless normal contact problem is solved first, then the tangential force is gradually increased, until gross sliding inception. The contact problems in the normal and in the tangential direction are successively solved, until one is stabilized in relation to the other. The maximum tangential force leading to a non-vanishing stick area is the static friction force that can be sustained by the rough contact. The static friction coefficient is eventually derived as the ratio between the latter friction force and the normal force.

  6. SPH modelling of depth‐limited turbulent open channel flows over rough boundaries

    Science.gov (United States)

    Kazemi, Ehsan; Nichols, Andrew; Tait, Simon

    2016-01-01

    Summary A numerical model based on the smoothed particle hydrodynamics method is developed to simulate depth‐limited turbulent open channel flows over hydraulically rough beds. The 2D Lagrangian form of the Navier–Stokes equations is solved, in which a drag‐based formulation is used based on an effective roughness zone near the bed to account for the roughness effect of bed spheres and an improved sub‐particle‐scale model is applied to account for the effect of turbulence. The sub‐particle‐scale model is constructed based on the mixing‐length assumption rather than the standard Smagorinsky approach to compute the eddy‐viscosity. A robust in/out‐flow boundary technique is also proposed to achieve stable uniform flow conditions at the inlet and outlet boundaries where the flow characteristics are unknown. The model is applied to simulate uniform open channel flows over a rough bed composed of regular spheres and validated by experimental velocity data. To investigate the influence of the bed roughness on different flow conditions, data from 12 experimental tests with different bed slopes and uniform water depths are simulated, and a good agreement has been observed between the model and experimental results of the streamwise velocity and turbulent shear stress. This shows that both the roughness effect and flow turbulence should be addressed in order to simulate the correct mechanisms of turbulent flow over a rough bed boundary and that the presented smoothed particle hydrodynamics model accomplishes this successfully. © 2016 The Authors International Journal for Numerical Methods in Fluids Published by John Wiley & Sons Ltd PMID:28066121

  7. SPH modelling of depth-limited turbulent open channel flows over rough boundaries.

    Science.gov (United States)

    Kazemi, Ehsan; Nichols, Andrew; Tait, Simon; Shao, Songdong

    2017-01-10

    A numerical model based on the smoothed particle hydrodynamics method is developed to simulate depth-limited turbulent open channel flows over hydraulically rough beds. The 2D Lagrangian form of the Navier-Stokes equations is solved, in which a drag-based formulation is used based on an effective roughness zone near the bed to account for the roughness effect of bed spheres and an improved sub-particle-scale model is applied to account for the effect of turbulence. The sub-particle-scale model is constructed based on the mixing-length assumption rather than the standard Smagorinsky approach to compute the eddy-viscosity. A robust in/out-flow boundary technique is also proposed to achieve stable uniform flow conditions at the inlet and outlet boundaries where the flow characteristics are unknown. The model is applied to simulate uniform open channel flows over a rough bed composed of regular spheres and validated by experimental velocity data. To investigate the influence of the bed roughness on different flow conditions, data from 12 experimental tests with different bed slopes and uniform water depths are simulated, and a good agreement has been observed between the model and experimental results of the streamwise velocity and turbulent shear stress. This shows that both the roughness effect and flow turbulence should be addressed in order to simulate the correct mechanisms of turbulent flow over a rough bed boundary and that the presented smoothed particle hydrodynamics model accomplishes this successfully. © 2016 The Authors International Journal for Numerical Methods in Fluids Published by John Wiley & Sons Ltd.

  8. General Regularities of Wood Surface Roughness

    Directory of Open Access Journals (Sweden)

    MAGOSS, Endre

    2008-01-01

    Full Text Available The surface roughness of wood products is depending on many factors related both towood properties and wood working operational parameters. Probably this is the reason why there areno generally valid correlation determining surface roughness parameters as a function of influencingfactors. In particular, the account of wood structure in the surface roughness interpretation proved tobe difficult.In the last years an important progress was made in recognizing the role of the anatomicalstructure of wood species in the attainable surface roughness. The introduction of a structure numbermade it possible to express and characterize the different wood species numerically.The aim of these studies was the separation of roughness components due to the anatomicalstructure and the woodworking operation. Using a special finishing technique, the roughnesscomponent due to woodworking operations was not significant and could be separated. The samespecimens were also subjected to different woodworking operations using cutting velocities between10 and 50 m/s. The processing of experimental data resulted in a chart showing the minimumroughness component due to different woodworking operations. Special experimental investigationwas conducted to clear the influence of edge dullness on the surface roughness, especially on itsAbbott-parameters. The measurements showed that the Rk-parameter is a good indicator to predictedge dullness.

  9. Testing of an Annular Linear Induction Pump for the Fission Surface Power Technology Demonstration Unit

    Science.gov (United States)

    Polzin, K. A.; Pearson, J. B.; Webster, K.; Godfoy, T. J.; Bossard, J. A.

    2013-01-01

    Results of performance testing of an annular linear induction pump that has been designed for integration into a fission surface power technology demonstration unit are presented. The pump electromagnetically pushes liquid metal (NaK) through a specially-designed apparatus that permits quantification of pump performance over a range of operating conditions. Testing was conducted for frequencies of 40, 55, and 70 Hz, liquid metal temperatures of 125, 325, and 525 C, and input voltages from 30 to 120 V. Pump performance spanned a range of flow rates from roughly 0.3 to 3.1 L/s (4.8 to 49 gpm), and pressure heads of three-phase power at 40 and 55 Hz using a variable-frequency motor drive, while power at 55 and 70 Hz was supplied using a variable-frequency power supply. Measured performance of the pump at 55 Hz using either supply exhibited good quantitative agreement. For a given temperature, the peak in efficiency occurred at different flow rates as the frequency was changed, but the maximum value of efficiency was relative insensitive within 0.3% over the frequency range tested, including a scan from 45 to 78 Hz. The objectives of the FSP technology project are as follows:5 • Develop FSP concepts that meet expected surface power requirements at reasonable cost with added benefits over other options. • Establish a nonnuclear hardware-based technical foundation for FSP design concepts to reduce overall development risk. • Reduce the cost uncertainties for FSP and establish greater credibility for flight system cost estimates. • Generate the key nonnuclear products to allow Agency decision makers to consider FSP as a viable option for potential future flight development. The pump must be compatible with the liquid NaK coolant and have adequate performance to enable a viable flight system. Idaho National Laboratory (INL) was tasked with the design and fabrication of an ALIP suitable for the FSP reference mission. Under the program, a quarter-scale FSP technology

  10. Rough Set Based Splitting Criterion for Binary Decision Tree Classifiers

    National Research Council Canada - National Science Library

    Mikulski, Dariusz G

    2006-01-01

    ...%ation based on rough set theory - the rough product. The rough product helps us to understand the manner in which an attribute value partition affects the upper approximation for each decision class...

  11. Rectangle-capped and tilted micropillar array for enhanced anisotropic anti-shearing in biomimetic adhesion.

    Science.gov (United States)

    Wang, Yue; Li, Xiangming; Tian, Hongmiao; Hu, Hong; Tian, Yu; Shao, Jinyou; Ding, Yucheng

    2015-05-06

    Dry adhesion observed in the feet of various small creatures has attracted considerable attention owing to the unique advantages such as self-cleaning, adaptability to rough surfaces along with repeatable and reversible adhesiveness. Among these advantages, for practical applications, proper detachability is critical for dry adhesives with artificial microstructures. In this study, we present a microstructured array consisting of both asymmetric rectangle-capped tip and tilted shafts, which produce an orthogonal anisotropy of the shearing strength along the long and short dimensions of the tip, with a maximum anti-shearing in the two directions along the longer dimension. Meanwhile, the tilt feature can enhance anisotropic shearing adhesion by increasing shearing strength in the forward shearing direction and decreasing strength in the reverse shearing direction along the short dimension of the tip, leading to a minimum anti-shearing in only one of the two directions along the shorter dimension of the rectangular tip. Such a microstructured adhesive with only one weak shearing direction, leading to well-controlled attachment and detachment of the adhesive, is created in our experiment by conventional double-sided exposure of a photoresist followed by a moulding process. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  12. Area Expansivity Moduli of Regenerating Plant Protoplast Cell Walls Exposed to Shear Flows

    Science.gov (United States)

    Fujimura, Yuu; Iino, Masaaki; Watanabe, Ugai

    2005-05-01

    To control the elasticity of the plant cell wall, protoplasts isolated from cultured Catharanthus roseus cells were regenerated in shear flows of 115 s-1 (high shear) and 19.2 s-1 (low shear, as a control). The surface area expansivity modulus and the surface breaking strength of these regenerating protoplasts were measured by a micropipette aspiration technique. Cell wall synthesis was also measured using a cell wall-specific fluorescent dye. High shear exposure for 3 h doubled both the surface area modulus and breaking strength observed under low shear, significantly decreased cell wall synthesis, and roughly quadrupled the moduli of the cell wall. Based on the cell wall synthesis data, we estimated the three-dimensional modulus of the cell wall to be 4.1± 1.2 GPa for the high shear, and 0.35± 0.2 GPa for the low shear condition, using the surface area expansivity modulus divided by the cell wall thickness, which is identical with the Young’s modulus divided by 2(1-σ), where σ is Poisson's ratio. We concluded that high shear exposure considerably strengthens the newly synthesized cell wall.

  13. A Piezoelectric Shear Stress Sensor

    Science.gov (United States)

    Kim, Taeyang; Saini, Aditya; Kim, Jinwook; Gopalarathnam, Ashok; Zhu, Yong; Palmieri, Frank L.; Wohl, Christopher J.; Jiang, Xiaoning

    2016-01-01

    In this paper, a piezoelectric sensor with a floating element was developed for shear stress measurement. The piezoelectric sensor was designed to detect the pure shear stress suppressing effects of normal stress generated from the vortex lift-up by applying opposite poling vectors to the: piezoelectric elements. The sensor was first calibrated in the lab by applying shear forces and it showed high sensitivity to shear stress (=91.3 +/- 2.1 pC/Pa) due to the high piezoelectric coefficients of PMN-33%PT (d31=-1330 pC/N). The sensor also showed almost no sensitivity to normal stress (less than 1.2 pC/Pa) because of the electromechanical symmetry of the device. The usable frequency range of the sensor is 0-800 Hz. Keywords: Piezoelectric sensor, shear stress, floating element, electromechanical symmetry

  14. Mitral valve annular downsizing forces: implications for annuloplasty device development.

    Science.gov (United States)

    Jensen, Morten O; Honge, Jesper L; Benediktsson, Jon A; Siefert, Andrew W; Jensen, Henrik; Yoganathan, Ajit P; Snow, Teresa K; Hasenkam, J Michael; Nygaard, Hans; Nielsen, Sten L

    2014-07-01

    Mitral valve repair with annulus downsizing is a popular surgical procedure for functional mitral regurgitation. We investigated the effects of externally applied downsizing on the observed in-plane forces and valvular dimensions. Five animals were included in an acute porcine study. Three traction sutures were anchored at the right fibrous trigone (T) and suspended across the annulus for externalization at the P1, P2, and P3 annular segments. The annulus was downsized with the sutures in controlled increments while measuring the tension force in the sutures. Downsizing percentages ranged from a 2% to 32% reduction of the T-P distances. Sonomicrometry was used to measure the resulting valvular dimensions. No difference in force was found between the P1, P2, and P3 segments across all levels of downsizing. The peak forces at 32% downsizing were 1.2 ± 0.9 N, 1.5 ± 1.0 N, and 0.8 ± 0.2 N for the T-P1, T-P2, and T-P3 segments, respectively. The maximum total suture forces in the mitral plane during downsizing increased from 0.12 ± 0.03 N to 3.5 ± 1.3 N (P downsizing (0%-32%) from 5 ± 3 mm to 1 ± 1 mm (P downsizing increased in-plane traction suture forces and has a significant influence on the in-plane biomechanics. These results have implications for device design in terms of mechanical strength requirements and can be used to supplement boundary conditions for computational left heart models. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  15. Uninstrumented assembly airflow testing in the Annular Flow Distribution facility

    Energy Technology Data Exchange (ETDEWEB)

    Kielpinski, A.L.

    1992-02-01

    During the Emergency Cooling System phase of a postulated large-break loss of coolant accident (ECS-LOCA), air enters the primary loop and is pumped down the reactor assemblies. One of the experiments performed to support the analysis of this accident was the Annular Flow Distribution (AFD) experiment, conducted in a facility built for this purpose at Babcock and Wilcox Alliance Research Center in Alliance, Ohio. As part of this experiment, a large body of airflow data were acquired in a prototypical mockup of the Mark 22 reactor assembly. This assembly was known as the AFD (or the I-AFD here) reference assembly. The I-AFD assembly was fully prototypical, having been manufactured in SRS`s production fabrication facility. Similar Mark 22 mockup assemblies were tested in several test facilities in the SRS Heat Transfer Laboratory (HTL). Discrepancies were found. The present report documents further work done to address the discrepancy in airflow measurements between the AFD facility and HTL facilities. The primary purpose of this report is to disseminate the data from the U-AFD test, and to compare these test results to the I-AFD data and the U-AT data. A summary table of the test data and the B&W data transmittal letter are included as an attachment to this report. The full data transmittal volume from B&W (including time plots of the various instruments) is included as an appendix to this report. These data are further analyzed by comparing them to two other HTL tests, namely, SPRIHTE 1 and the Single Assembly Test Stand (SATS).

  16. Effect of roughness on water flow through a single rough fracture

    Science.gov (United States)

    Chen, Z.; Zhou, Z.; WANG, J.; Guo, Q.; Dou, Z.

    2015-12-01

    A single fracture (SF) usually has rough surfaces with points of contact. Though relative roughness was considered in quantifying flow through a single rough fracture (SRF) previously, additional factors such as the distribution of rough elements and bending degree of streamlines are rarely considered before. Semi-empirical friction factor (f) and discharge per unit width (q) equations are first deduced based on the consideration of relative roughness, roughness elements distribution and streamline reattachment length in this study. A horizontal SRF model is set up and a series of experiments and simulations are performed. Main conclusions are drawn: recirculation of streamlines occurred in the rough element and its intensity increases with the entering angle of the streamlines into the element and Reynolds number (Re); streamlines are discontinuously distributed when asperity height is large, leading to departure from Darcy's law (non-linear flow); the non-linearity of flow increases with the asperity height and Re; the relative roughness for not affecting water flow through a SRF should be much less than 0.033, a benchmark value commonly used previously for neglecting the roughness effect; the revised f and q equations under laminar flow through a SRF are shown to be better than previously proposed equations.

  17. Mitigating mask roughness via pupil filtering

    Science.gov (United States)

    Baylav, B.; Maloney, C.; Levinson, Z.; Bekaert, J.; Vaglio Pret, A.; Smith, B.

    2014-03-01

    The roughness present on the sidewalls of lithographically defined patterns imposes a very important challenge for advanced technology nodes. It can originate from the aerial image or the photoresist chemistry/processing [1]. The latter remains to be the dominant group in ArF and KrF lithography; however, the roughness originating from the mask transferred to the aerial image is gaining more attention [2-9], especially for the imaging conditions with large mask error enhancement factor (MEEF) values. The mask roughness contribution is usually in the low frequency range, which is particularly detrimental to the device performance by causing variations in electrical device parameters on the same chip [10-12]. This paper explains characteristic differences between pupil plane filtering in amplitude and in phase for the purpose of mitigating mask roughness transfer under interference-like lithography imaging conditions, where onedirectional periodic features are to be printed by partially coherent sources. A white noise edge roughness was used to perturbate the mask features for validating the mitigation.

  18. Suppression of intrinsic roughness in encapsulated graphene

    Science.gov (United States)

    Thomsen, Joachim Dahl; Gunst, Tue; Gregersen, Søren Schou; Gammelgaard, Lene; Jessen, Bjarke Sørensen; Mackenzie, David M. A.; Watanabe, Kenji; Taniguchi, Takashi; Bøggild, Peter; Booth, Timothy J.

    2017-07-01

    Roughness in graphene is known to contribute to scattering effects which lower carrier mobility. Encapsulating graphene in hexagonal boron nitride (hBN) leads to a significant reduction in roughness and has become the de facto standard method for producing high-quality graphene devices. We have fabricated graphene samples encapsulated by hBN that are suspended over apertures in a substrate and used noncontact electron diffraction measurements in a transmission electron microscope to measure the roughness of encapsulated graphene inside such structures. We furthermore compare the roughness of these samples to suspended bare graphene and suspended graphene on hBN. The suspended heterostructures display a root mean square (rms) roughness down to 12 pm, considerably less than that previously reported for both suspended graphene and graphene on any substrate and identical within experimental error to the rms vibrational amplitudes of carbon atoms in bulk graphite. Our first-principles calculations of the phonon bands in graphene/hBN heterostructures show that the flexural acoustic phonon mode is localized predominantly in the hBN layer. Consequently, the flexural displacement of the atoms in the graphene layer is strongly suppressed when it is supported by hBN, and this effect increases when graphene is fully encapsulated.

  19. Prenatal Diagnosis of Annular Pancreas: Reliability of the Double Bubble Sign with Periduodenal Hyperechogenic Band

    Science.gov (United States)

    Dankovcik, Robert; Jirasek, Jan E.; Kucera, Eduard; Feyereisl, Jaroslav; Radonak, Jozef; Dudas, Marek

    2009-01-01

    Objective To evaluate the power of prenatal 2-D ultrasound examination in the 2nd trimester as a method of choice for accurate diagnosis of annular pancreas. Methods Co-incidence of the double bubble sign (often accompanying gastroduodenal dilatation) together with a hyperechogenic band around the duodenum (corresponding with the tissue of annular pancreas) was used as a diagnostic criterion. Findings from postnatal surgery served for verification. Results From 7,897 screened pregnancies, annular pancreas was proven in the cases where both signs were present, but never without the hyperechogenic band (N1 = 3, N2 = 3, p ≤ 0.05). Sensitivity and specificity were 100%. Conclusions More multicentric studies are required to test this approach. The following diagnostic strategy is reasonable at the present time: when the double bubble sign is discovered, always suspect annular pancreas and look for the second sign: hyperechogenic bands around the duodenum. Also look for known associated anomalies, and vice versa, if any of associated anomalies are noted, also search specifically for the signs of annular pancreas. PMID:19047797

  20. Measuring Orbital Angular Momentum (OAM) States of Vortex Beams with Annular Gratings.

    Science.gov (United States)

    Zheng, Shuang; Wang, Jian

    2017-01-17

    Measuring orbital angular momentum (OAM) states of vortex beams is of great importance in diverse applications employing OAM-carrying vortex beams. We present a simple and efficient scheme to measure OAM states (i.e. topological charge values) of vortex beams with annular gratings. The magnitude of the topological charge value is determined by the number of dark fringes after diffraction, and the sign of the topological charge value is distinguished by the orientation of the diffraction pattern. We first theoretically study the diffraction patterns using both annular amplitude and phase gratings. The annular phase grating shows almost 10-dB better diffraction efficiency compared to the annular amplitude grating. We then experimentally demonstrate the OAM states measurement of vortex beams using annular phase grating. The scheme works well even for high-order vortex beams with topological charge value as high as ± 25. We also experimentally show the evolution of diffraction patterns when slightly changing the fractional topological charge value of vortex beam from 0.1 to 1.0. In addition, the proposed scheme shows potential large tolerance of beam alignment during the OAM states measurement of vortex beams.

  1. Numerical and experimental study of an annular pulse tube used in the pulse tube cooler

    Science.gov (United States)

    Pang, Xiaomin; Chen, Yanyan; Wang, Xiaotao; Dai, Wei; Luo, Ercang

    2017-12-01

    Multi-stage pulse tube coolers normally use a U-type configuration. For compactness, it is attractive to build a completely co-axial multi-stage pulse tube cooler. In this way, an annular shape pulse tube is inevitable. Although there are a few reports about previous annular pulse tubes, a detailed study and comparison with a circular pulse tube is lacking. In this paper, a numeric model based on CFD software is carried out to compare the annular pulse tube and circular pulse tube used in a single stage in-line type pulse tube cooler with about 10 W of cooling power at 77 K. The length and cross sectional area of the two pulse tubes are kept the same. Simulation results show that the enthalpy flow in the annular pulse tube is lower by 1.6 W (about 11% of the enthalpy flow) compared to that in circular pulse tube. Flow and temperature distribution characteristics are also analyzed in detail. Experiments are then conducted for comparison with an in-line type pulse tube cooler. With the same acoustic power input, the pulse tube cooler with a circular pulse tube obtains 7.88 W of cooling power at 77 K, while using an annular pulse tube leads to a cooling power of 7.01 W, a decrease of 0.9 W (11.4%) on the cooling performance. The study sets the basis for building a completely co-axial two-stage pulse tube cooler.

  2. Shear Layer Interactions in the Helical Hydrodynamic Structures of Swirling, Reacting Jets

    Science.gov (United States)

    Smith, Travis; Manoharan, Kiran; Emerson, Benjamin; Hemchandra, Santosh; Lieuwen, Tim

    2016-11-01

    Swirling jets with density stratification are a canonical combustor flow field. This work consisted of coupled experimental and theoretical analysis of the spatial structure of the most amplified modes in an annular jet, with a specific focus on the radial mode shapes of the shear layer disturbances, which we characterize as inner shear layer (ISL) motion relative to outer shear layer (OSL) motion. The stability analysis identifies spatial structures dominated by ISL motion, modes dominated by OSL motion, and modes with mixed ISL and OSL motion. These mixed modes are further classified as sinuous or varicose radial structures, depending on the relative motions of the two shear layers. The presence and spatial dependencies of these spatial modes are demonstrated experimentally with a 5 kHz stereo PIV measurement of a reacting swirling jet. In the experiment, we demonstrate that external excitations of various spatial configurations can be used to elicit hydrodynamic responses of axisymmetric and helical motions in either the ISL, the OSL, or the sinuous or varicose radial modes.

  3. Calcium phosphorus bio-coating on carbon/carbon composites: Preparation, shear strength and bioactivity

    Science.gov (United States)

    Su, Yangyang; Li, Kezhi; Zhang, Leilei; Liu, Shoujie; Yuan, Ye; He, Song

    2017-10-01

    Microwave hydrothermal (MH) combining supersonic atmospheric plasma sprayed (SAPS) calcium phosphorus (Ca-P) bio-coatings on carbon/carbon (C/C) composite has been widely used due to their osteoconductivity and osteoproductivity. However, the erratic shear strength between coatings prepared only by SAPS (outer coating) and C/C substrates has attached more attention over the implant failure. Adding a coating prepared by MH (inner coating) before SAPS can possess superior shear strength to conventional outer coating. The inner coating with fine Ca-P particles was prepared through a unique MH method under different concentrations (10, 500 and 1000 mmol/L). The influence of concentration on microstructure, phase composition, roughness and shear strength are investigated in this paper. In particularly, the roughness of inner coatings on C/C substrates was found to related to the morphologies and particle size. Results showed that inner coatings have higher roughness which was beneficial for the promotion of shear strength between the obtained Ca-P bio-coating and the C/C substrates. Subsequently, the specimens were immersed in a simulated body fluid (SBF) to investigate the bioactivity.

  4. Bottom friction and wave-induced roughness

    Science.gov (United States)

    Lepesqueur, J.; Ardhuin, F.; Bennis, A.-C.

    2012-04-01

    The parameterization of the interaction of waves with a sandy bottom including ripple generation and relict ripple roughness (Ardhuin et al. 2003) using the sub-grid roughness algorithm by Tolman (1995) has been implemented in the WAVEWATCH III model and generalized to take into account the variability of the bottom nature, including rock and cohesive sediments. The model is applied with a triangle-based mesh to both the U.S. East-Coast and the French Atlantic to North Sea coasts. The hindcast wave heights over the North Carolina continental shelf during the SHOaling Waves EXperiment reproduce the results of Ardhuin et al. (2003). The new application in the English Channel and Southern North see shows a general better result that with the JONSWAP parameterization. In particular the use of realistic roughness is important with gravel in the central Channel and sand or sand/silt mixtures in the southern North Sea.

  5. Spin Hall effect by surface roughness

    KAUST Repository

    Zhou, Lingjun

    2015-01-08

    The spin Hall and its inverse effects, driven by the spin orbit interaction, provide an interconversion mechanism between spin and charge currents. Since the spin Hall effect generates and manipulates spin current electrically, to achieve a large effect is becoming an important topic in both academia and industries. So far, materials with heavy elements carrying a strong spin orbit interaction, provide the only option. We propose here a new mechanism, using the surface roughness in ultrathin films, to enhance the spin Hall effect without heavy elements. Our analysis based on Cu and Al thin films suggests that surface roughness is capable of driving a spin Hall angle that is comparable to that in bulk Au. We also demonstrate that the spin Hall effect induced by surface roughness subscribes only to the side-jump contribution but not the skew scattering. The paradigm proposed in this paper provides the second, not if only, alternative to generate a sizable spin Hall effect.

  6. Fifty years of shear zones

    Science.gov (United States)

    Graham, Rodney

    2017-04-01

    We are here, of course, because 1967 saw the publication of John Ramsay's famous book. Two years later a memorable field trip from Imperial College to the Outer Hebrides saw John on a bleak headland on the coast of North Uist where a relatively undeformed metadolerite within Lewisian (Precambrian) gneisses contained ductile shear zones with metamorphic fabrics in amphibolite facies. One particular outcrop was very special - a shear zone cutting otherwise completely isotropic, undeformed metadolerite, with an incremental foliation starting to develop at 45° to the deformation zone, and increasing in intensity as it approached the shear direction. Here was proof of the process of simple shear under ductile metamorphic conditions - the principles of simple shear outlined in John Ramsay's 1967 book clearly visible in nature, and verified by Ramsay's mathematical proofs in the eventual paper (Ramsay and Graham, 1970). Later work on the Lewisian on the mainland of Scotland, in South Harris, in Africa, and elsewhere applied Ramsay's simple shear principles more liberally, more imprecisely and on larger scale than at Caisteal Odair, but in retrospect it documented what seems now to be the generality of mid and lower crustal deformation. Deep seismic reflection data show us that on passive margins hyper-stretched continental crust (whether or not cloaked by Seaward Dipping Reflectors) seems to have collapsed onto the mantle. Crustal faults mostly sole out at or above the mantle - so the Moho is a detachment- an 'outer marginal detachment', if you like, and, of course, it must be a ductile shear. On non-volcanic margins this shear zone forms the first formed ocean floor before true sea floor spreading gets going to create real oceanic crust. Gianreto Manatschal, Marcel Lemoine and others realised that the serpentinites described in parts of the Alps are exposed remnants of this ductile shear zone. Associated ophicalcite breccias tell of sea floor exposure, while high

  7. Experimental investigation of turbulent flow-roughness interaction over surfaces of rigid and flexible roughness

    Science.gov (United States)

    Toloui, Mostafa; Hong, Jiarong

    2017-11-01

    The influence of flexible surface roughness on wall-bounded turbulent flows is examined experimentally via simultaneous 3D fluid velocity and roughness deformation measurements using Digital inline holographic PTV (i.e. DIH-PTV, Toloui et al. Meas. Sci. & Tech 2017). The experiments are conducted in a refractive-index-matched turbulent channel over two rough surface panels of similar geometry but with an order of magnitude difference in elastic modulus (1.8 Mpa vs. 0.2 Mpa). The roughness elements (i.e. tapered cylinders of 0.35 mm in base diameter, 3 mm in height, 4 mm spacing) are designed such that the rough surface with higher modulus shows no deformation (namely rigid roughness) while the one with lower elasticity deforms appreciably under the same flow conditions (Reh 32500 , based on centerline velocity and channel width). The concurrent fluid velocity and roughness deformation measurements are acquired with 160 μs temporal, 1.1 mm/vector velocity, and linked to roughness deformation. The fingerprint of this energy exchange on shortening the instantaneous flow structures, reduction of Reynolds stresses as well as flow features in energy spectra are examined and will be presented in detail.

  8. Beyond the Cosmological: Numerical Scenarios underneath Ancient Annular Architectural Structures

    Science.gov (United States)

    Ranieri, M.

    2009-08-01

    ``Cecì est la regle du carré et du cercle. Pour toutes choses, la circonférence (tcheou) est en usage, et les figures circulaire et carrée sont employées. L'officier dit ta-tsiang (grand charpentier, titre du Tcheou-li) prend ses mesures. Le compass et le règle sont apprêtés. Tantot on rompt le carré et on fait un cercle. Tantot on brise le cercle et on fait un carré. Au milieu d'un carré, quand on fait un cercle, on appelle cette figure cercle-carré. Au milieu d'un cercle, quand on fait un carré, on appelle cette figure carré-cercle.'' (Tcheou-Pei-Souan-King, book one, trad. E.Biot, Journal Asiatique, Juin 1841 p. 614 Circles and squares, as geometrical representations of the cosmos, are frequent in ancient cultures, mainly with the earth represented by the square and the sky by the circle. Quite many are the circular or circle-and-square architectures of the past that are to be interpreted as related to the cosmologies of the cultures to which they belong. In this paper we focus on those relevant annular geometries (CQC) where the square inscribable into the external circumference in turn perfectly circumscribes the internal one. Beyond the possible cosmological significances, a CQC geometry bears underneath a strict numerical structure that can be put in relation to the length-units used by the builders. Results are presented of CAD (Computer Aided Drawing) analyses performed on the plans of ancient structures where the CQC geometry was suspected to exist. A large repertory of such structures has been found, from Nuragic Sardinia to Mesoamerica including Minoans, Greeks, Romans and others. In many cases the found length-units coincide with known ancient units. The large variety presented at CAC 2000 cannot be shown in this paper for reasons of space and only a smaller but significant selection is presented.

  9. DEFORMATION ROUGHNESS UNDER CYCLIC AND STATIC LOADS

    Directory of Open Access Journals (Sweden)

    О.М. Karuskevich

    2005-02-01

    Full Text Available  The experiments are aimed to develop a new non-destructive method for fatigue damage diagnostics. This method is based on monitoring deformation roughness which is formed on the surface of aluminum structural alloys. The evolution of this roughness near the stress concentrator has been monitored at various stages of fatigue life under the stress level close to the operational stress level on the fuselage skin of modern aircraft. The deformation relief under static loads  is represented as well.

  10. Hailstone classifier based on Rough Set Theory

    Science.gov (United States)

    Wan, Huisong; Jiang, Shuming; Wei, Zhiqiang; Li, Jian; Li, Fengjiao

    2017-09-01

    The Rough Set Theory was used for the construction of the hailstone classifier. Firstly, the database of the radar image feature was constructed. It included transforming the base data reflected by the Doppler radar into the bitmap format which can be seen. Then through the image processing, the color, texture, shape and other dimensional features should be extracted and saved as the characteristic database to provide data support for the follow-up work. Secondly, Through the Rough Set Theory, a machine for hailstone classifications can be built to achieve the hailstone samples’ auto-classification.

  11. Fuzzy sets, rough sets, multisets and clustering

    CERN Document Server

    Dahlbom, Anders; Narukawa, Yasuo

    2017-01-01

    This book is dedicated to Prof. Sadaaki Miyamoto and presents cutting-edge papers in some of the areas in which he contributed. Bringing together contributions by leading researchers in the field, it concretely addresses clustering, multisets, rough sets and fuzzy sets, as well as their applications in areas such as decision-making. The book is divided in four parts, the first of which focuses on clustering and classification. The second part puts the spotlight on multisets, bags, fuzzy bags and other fuzzy extensions, while the third deals with rough sets. Rounding out the coverage, the last part explores fuzzy sets and decision-making.

  12. ROUGHNESS LENGTHS FOR THE SAVANNAH RIVER SITE

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, C.

    2012-03-28

    Surface roughness values for the areas surrounding the H, D and N-Area meteorological towers were computed from archived 2010 meteorological data. These 15-minute-averaged data were measured with cup anemometers and bidirectional wind vanes (bivanes) 61 m above the surface. The results of the roughness calculation using the standard deviation of elevation angle {sigma}{sub E}, and applying the simple formula based on tree canopy height, gave consistent estimates for roughness around the H-Area tower in the range of 1.76 to 1.86 m (95% confidence interval) with a mean value of 1.81 m. Application of the {sigma}{sub E} method for the 61-m level at D and N-Areas gave mean values of 1.71 and 1.81 with confidence ranges of 1.62-1.81 and 1.73-1.88 meters, respectively. Roughness results are azimuth dependent, and thus are presented as averages over compass sectors spanning 22.5 degrees. Calculated values were compared to other methods of determining roughness, including the standard deviation of the azimuth direction, {sigma}{sub A}, and standard deviation of the wind speed, {sigma}{sub U}. Additional data was obtained from a sonic anemometer at 61-m on the H-Area tower during a period of a few weeks in 2010. Results from the sonic anemometer support our use of {sigma}{sub E} to calculate roughness. Based on the H-Area tower results, a surface roughness of 1.8 m using is recommended for use in dispersion modeling applications that consider the impacts of a contaminant release to individuals along the Site boundary. The canopy surrounding the H-Area tower is relatively uniform (i.e., little variance in roughness by upwind direction), and data supplied by the U.S. Forest Service at Savannah River show that the canopy height and composition surrounding the H-Area tower is reasonably representative of forested areas throughout the SRS reservation. For dispersion modeling analyses requiring assessments of a co-located worker within the respective operations area, recommended

  13. Nanodrop impact on rough and textured surfaces

    Science.gov (United States)

    Zhang, Rui; Koplik, Joel

    2012-11-01

    We use molecular dynamics simulations to investigate the impact of a nanometer-sized drop onto structured atomic surfaces. Rough surfaces with Gaussian or power-law correlations are constructed using a Fourier synthesis algorithm. At low impact velocity drops spread into a lamella, and we study its shape and maximum extension as a function of surface roughness and wettability. At higher impact velocities a prompt splash occurs, and we examine the effects of the surface and external vapor on the behavior of the lamella rim. We also consider the effect of surface wettability patterns on splashing and spreading, and compare the results to lattice-Boltzmann simulations in the same geometry.

  14. Prediction of Ductile Fracture Surface Roughness Scaling

    DEFF Research Database (Denmark)

    Needleman, Alan; Tvergaard, Viggo; Bouchaud, Elisabeth

    2012-01-01

    Experimental observations have shown that the roughness of fracture surfaces exhibit certain characteristic scaling properties. Here, calculations are carried out to explore the extent to which a ductile damage/fracture constitutive relation can be used to model fracture surface roughness scaling...... three dimensional stress and deformation states that develop in the fracture process region. An elastic-viscoplastic constitutive relation for a progressively cavitating plastic solid is used to model the material. Two populations of second phase particles are represented: large inclusions with low....... The scaling properties of the predicted thickness average fracture surfaces are calculated and the results are discussed in light of experimental observations....

  15. Wall-slip of highly filled powder injection molding compounds: Effect of flow channel geometry and roughness

    Science.gov (United States)

    Hausnerova, Berenika; Sanetrnik, Daniel; Paravanova, Gordana

    2014-05-01

    The paper deals with the rheological behavior of highly filled compounds proceeded via powder injection molding (PIM) and applied in many sectors of industry (automotive, medicine, electronic or military). Online rheometer equipped with slit dies varying in surface roughness and dimensions was applied to investigate the wall-slip as a rheological phenomenon, which can be considered as a parameter indicating the separation of compound components (polymer binder and metallic powder) during high shear rates when injection molded.

  16. Detecting the topological charge of vortex beams using an annular triangle aperture

    Science.gov (United States)

    Yongxin, Liu; Hua, Tao; Jixiong, Pu; Baida, Lü

    2011-10-01

    The Fraunhofer diffraction pattern of a vortex beam by an annular triangle aperture is analyzed theoretically and experimentally. It is found that the pattern of the far-field diffraction intensity distribution exhibits a triangular lattice array, which becomes much clearer with the increase of the ratio of the inner to the outer side of the annular triangle aperture. The number of spot points of any external side of the triangular lattice array minus one is just equal to the topological charge value of the measured optical vortex. For the vortex beam with negative topological charge, the triangular diffraction pattern after the annular triangle aperture will be rotated by 180° in relation to the case of the positive topological charge. Based on the above properties, we propose a simple and feasible method to determine the magnitude and sign of the topological charge of an optical vortex beam.

  17. On the electrodynamics of counter stream in pulsar’s inner annular cap region

    Science.gov (United States)

    Lee, K. J.; Qiao, G. J.; Wang, H. G.; Xu, R. X.

    The electric properties of pulsar’s inner annular gap are explored in this paper. Under two main assumptions, (1) the pulsar is alive, (2) the total charge of pulsar should not vary with time, the condition for the acceleration of negative particle in the annular region is derived. The acceleration condition is j- ⩾ 0.5j+, i.e., the current carried by negative particles is greater than or equal to 0.5 times of the current carried by positive particles. This condition holds even when the backward flow of positive particles exists in the annular region. It is noted that the outflow of negative particles offers good opportunities to understand the current closure problem of pulsar as well as wide radiation beam of pulsar observed at high energy band.

  18. Annular nanoplasmonic void arrays as tunable surface enhanced Raman spectroscopy substrates

    Science.gov (United States)

    Li, Zhibo; Clark, Alasdair W.; Cooper, Jonathan M.

    2014-07-01

    We report the use of annular nano-voids in a metallic thin-film as programmable molecular sensors for surface-enhanced Raman spectroscopy (SERS). To date, research into these structures has focused on the exploration of their extraordinary optical transmission attributes. We now show that by using advanced lithography and simulation tools, we can generate a porous SERS material for molecular interrogation. Using ultra-thin annular structures, rather than simple circular holes, allows us to reduce both the volume and cross-sectional area of the void, maximizing the electric-field confinement, while, importantly for SERS, producing resonant conditions in the visible region of the spectrum. By comparing our annular films with conventional circular films with the same resonant frequency, we show a significant improvement in the efficiency of Raman scatter, creating stronger signals that also contain more spectral information.

  19. SEDflume - High Shear Stress Flume

    Data.gov (United States)

    Federal Laboratory Consortium — The U.S. Army Corps of Engineers High Shear Stress flume (SEDflume) is designed for estimating erosion rates of fine-grained and mixed fine/coarse grained sediments...

  20. Optimization of gap sizes for the high performance of annular nuclear fuels

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Young Doo; Kwon, Soon Bum; Cho, Hui Jeong; Kim, Seong Su [Kyungpook National University, Daegu (Korea, Republic of)

    2015-04-15

    Solid-type nuclear fuels have been used for nuclear reactors for a long time. Many countries are currently developing annular fuels to improve the efficiency of nuclear fuels. The thermoelastic-plastic-creep analyses of solid- and annular-type rods were conducted under the same conditions. The temperature and stress of the solid- and annular-type rods were compared on the basis of gap size. In this study, we examined the advantages and disadvantages of annular-type fuel regarding the temperature and stress of the pellet and cladding. The inner and outer gaps between the pellet and cladding play important roles in the temperature and stress distributions of fuel systems. Therefore, the optimization of gaps in fuel systems was conducted for a low temperature under certain stress conditions. hermoelasticplastic-creep analyses were conducted by using an in-house thermoelastic-plastic-creep finite element analysis program in Visual FORTRAN with the effective stress function algorithm. Nonlinear iterative stress analyses were conducted by nonlinear iterative temperature analyses; that is, a quasi-fully coupled algorithm was applied to this procedure. In this study, the thermoelastic-plastic-creep analysis of pressurized water reactor annular fuels was conducted to determine the contacting tendency of the inner-outer gaps between the annular fuel pellets and cladding, as well as to optimize the gap sizes by using the commercial package PIAnO for efficient heat transfer at certain stress levels. Most analyses were conducted until the gaps disappeared. However, certain analyses lasted for 1582 days, after which the fuels were replaced.

  1. Roughness-induced streaming in turbulent wave boundary layers

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Sumer, B. Mutlu; Fredsøe, Jørgen

    2011-01-01

    -averaged streaming characteristics induced by bottom roughness variations are systematically assessed. The effects of variable roughness ratio, gradual roughness transitions, as well as changing flow orientation in plan are all considered. As part of the latter, roughness-induced secondary flows are predicted...

  2. Studying laminar flows of power-law fluids in the annular channel with eccentricity

    Science.gov (United States)

    Zhigarev, V. A.; Neverov, A. L.; Guzei, D. V.; Pryazhnikov, M. I.

    2017-09-01

    The paper deals with numerical and experimental investigation of non-Newtonian flow of modeling drilling fluids in the annular channel. The Reynolds number was ranged from 100 to 1500. The parameters of the power-law model of drilling fluids were varied within the following ranges: n = 0.43-0.49, K = 0.22-0.89. The eccentricity was changed from 0 to 1. We have measured pressure drop in the annular channel and compared calculations with experimental data, achieving good agreement between calculations and experiment.

  3. DETERMINATION OF TEMPERATURE DISTRIBUTION FOR ANNULAR FINS WITH TEMPERATURE DEPENDENT THERMAL CONDUCTIVITY BY HPM

    Directory of Open Access Journals (Sweden)

    Davood Domairry Ganji

    2011-01-01

    Full Text Available In this paper, homotopy perturbation method has been used to evaluate the temperature distribution of annular fin with temperature-dependent thermal conductivity and to determine the temperature distribution within the fin. This method is useful and practical for solving the nonlinear heat transfer equation, which is associated with variable thermal conductivity condition. The homotopy perturbation method provides an approximate analytical solution in the form of an infinite power series. The annular fin heat transfer rate with temperature-dependent thermal conductivity has been obtained as a function of thermo-geometric fin parameter and the thermal conductivity parameter describing the variation of the thermal conductivity.

  4. Histological study of the annular ligament in the rabbitfish eye (Siganus sp.

    Directory of Open Access Journals (Sweden)

    Marziye Asli

    2012-12-01

    Full Text Available Rabbitfish is economically valuable teleost species which lives in shallow coastalwaters. Two species of rabbit fish have been recognized in southern sea of Iran (Persiangulf as namely Siganus sutor and Siganus javus. In the current study, in order toinvestigate the histology of the annular ligament of the S. javus’ eye, the prepared sectionsof the eyes of twelve healthy specimens were studied under light microscope. The resultsrevealed that annular ligament is a crescent shape structure which is situated between thescleral stroma anteriorly and the iris posteriorly. It contains a vascularized, amorphousand granular matrix with fibers of dense connective tissue; high glycogen content andmelanin pigments.

  5. An Evaluation of the Annular Fuel and Bottle-Shaped Fuel Concepts for Sodium Fast Reactors

    OpenAIRE

    Memmott, Matthew; Buongiorno, Jacopo; Hejzlar, Pavel

    2010-01-01

    Two innovative fuel concepts, the internally and externally cooled annular fuel and the bottle-shaped fuel, were investigated with the goal of increasing the power density and reduce the pressure drop in the sodium-cooled fast reactor, respectively. The concepts were explored for both high- and low-conversion core configurations, and metal and oxide fuels. The annular fuel concept is best suited for low-conversion metal-fuelled cores, where it can enable a power uprate of ~20%; the magnitude ...

  6. Association between the synthetic vascular stent used for abdominal aortic aneurysm and generalized granuloma annulare

    Directory of Open Access Journals (Sweden)

    Han-Chi Tseng

    2015-09-01

    Full Text Available The etiology of granuloma annulare (GA remains unknown, although several eliciting factors have been proposed. We herein present the case of an 81-year-old man who developed generalized erythematous annular plaques 6 months after engraftment of a vascular stent for abdominal aneurysm repair. Based on the diagnosis of generalized GA and the patient's age, we treated him with psoralens plus ultraviolet A therapy. The treatment response was good. This is the first report showing the association between vascular stent and generalized GA.

  7. Remodeling Mitral Annuloplasty Ring Concept with Preserved Dynamics of Annular Height

    DEFF Research Database (Denmark)

    Skov, Søren N; Røpcke, Diana M; Tjørnild, Marcell J

    2017-01-01

    . The change and maximum value of the annular height were maintained for the novel ring but were significantly decreased for the rigid and semi-rigid rings compared with the 'no-ring' group. Mitral annular force measurements confirmed that the overall remodeling capacity of the novel ring was comparable...... with the conventional ring groups, and significantly higher in the septal-lateral direction compared to the semi-rigid ring. CONCLUSIONS: In-vivo geometry and force measurements indicated that the intended design features of the new device were successfully provided. The novel ring concept with remodeling properties...

  8. More on neutrosophic soft rough sets and its modification

    Directory of Open Access Journals (Sweden)

    Emad Marei

    2015-12-01

    Full Text Available This paper aims to introduce and discuss anew mathematical tool for dealing with uncertainties, which is a combination of neutrosophic sets, soft sets and rough sets, namely neutrosophic soft rough set model. Also, its modification is introduced. Some of their properties are studied and supported with proved propositions and many counter examples. Some of rough relations are redefined as a neutrosophic soft rough relations. Comparisons among traditional rough model, suggested neutrosophic soft rough model and its modification, by using their properties and accuracy measures are introduced. Finally, we illustrate that, classical rough set model can be viewed as a special case of suggested models in this paper.

  9. Shear properties at the PyC/SiC interface of a TRISO-coating

    Science.gov (United States)

    Nozawa, T.; Snead, L. L.; Katoh, Y.; Miller, J. H.

    2007-09-01

    The failure behavior of TRISO-coated fuel particles depends significantly on the shear strength at the interface between the inner pyrolytic carbon (PyC) and silicon carbide (SiC) coatings. In this study, a micro-indentation fiber push-out test was applied to measure the interfacial shear properties of a model TRISO-coated tube. Of particular emphasis is that this study developed a non-linear shear-lag model for a transversely isotropic composite material due to insufficiency in the existing isotropic models as applied to layered TRISO-coating systems. In the model, the effects of thermal residual stresses and the roughness-induced clamping stress were identified as particularly important. The rigorous model proposed in this study provides more reasonable data on two important interfacial parameters: the interfacial debond shear strength and the interfacial friction stress. The modified model coupled with experiments yields an interfacial debond shear strength of 240 ± 40 MPa. This high interfacial strength, though slightly lower than that obtained by the existing isotropic model (˜280 MPa), allows significant loads to be transferred between inner PyC and SiC in application. Additionally, an interfacial friction stress of 120 ± 30 MPa was determined. This high friction stress is attributed primarily to the roughness at the cracked interface rather than clamping effects due to differing coefficients of thermal expansion.

  10. Impact of Acid Attack on the Shear Behaviour of a Carbonate Rock Joint

    Science.gov (United States)

    Nouailletas, O.; Perlot, C.; Rivard, P.; Ballivy, G.; La Borderie, C.

    2017-06-01

    The mechanical behaviour of structural discontinuities in rock mass is a key element of the stability analysis in civil engineering, petroleum engineering and mining engineering. In this paper, the mechanical analysis is coupled with the acidic attack of a rock joint associated with leakage of CO2 through a geological fault in the context of carbon sequestration. Experiments were conducted at the laboratory scale to assess the shear behaviour of degraded joint: direct shear tests were performed on rock joints that have been previously immersed into water or into an acidic solution (pH 0.2). The shear behaviour of joints is governed by the roughness of its walls: the parameters Z2, Z3, Z4 and RL characterize the rough surfaces. They are calculated from the scans of joint surfaces after and before immersion. Their comparison pointed out a slight impact of the acidic attack. However, the results of the direct shear tests show significant modifications in the shear behaviour for the degraded joints: the tangential stress peak disappears, the tangential stiffness decreases in the stress/displacement curve, and the contraction increases, the dilation angle decreases in the dilation curve. Acid attack has a greater impact on the mechanical properties of the asperities than their geometric characteristics. The results of this study will be used to improve chemo-mechanical modelling to better simulate with higher accuracy the fault stability in different cases of civil engineering, petroleum engineering and mining engineering.

  11. Mechanical and hydraulic behavior of a rock fracture under shear deformation

    Science.gov (United States)

    Nishiyama, Satoshi; Ohnishi, Yuzo; Ito, Hisao; Yano, Takao

    2014-12-01

    With regard to crystalline rock that constitutes deep geology, attempts have been made to explore its hydraulic characteristics by focusing on the network of numerous fractures within. As the hydraulic characteristics of a rock are the accumulation of hydraulic characteristics of each fracture, it is necessary to develop the hydraulic model of a single fracture to predict the large-scale hydraulic behavior. To this end, a simultaneous permeability and shear test device is developed, and shear-flow coupling tests are conducted on specimens having fractures with varied levels of surface roughness in the constant normal stiffness conditions. The results show that the permeability characteristics in the relation between shear displacement and transmissivity change greatly at the point where the stress path reaches the Mohr-Coulomb failure curve. It is also found that there exists a range in which transmissivity is not proportional to the cube of mechanical aperture width, which seems to be because of the occurrence of channeling phenomenon at small mechanical aperture widths. This channeling flow disappears with increasing shear and is transformed into a uniform flow. We develop a simulation technique to evaluate the macroscopic permeability characteristics by the lattice gas cellular automaton method, considering the microstructure of fracture, namely the fracture surface roughness. With this technique, it is shown that the formation of the Hagen-Poiseuille flow is affected by the fracture microstructure under shear, which as a result determines the relationship between the mechanical aperture width and transmissivity.

  12. High speed machined surface roughness measurement ...

    African Journals Online (AJOL)

    Surface roughness monitoring techniques using non-contact methods based on computer vision technology are becoming popular and cost effective. An evolvable hardware configuration using reconfigurable Xilinx Virtex FPGA xcv1000 architecture with capability to compensate for poor illumination environment is ...

  13. Potential roughness near lithographically fabricated atom chips

    DEFF Research Database (Denmark)

    Krüger, Peter; Andersson, L. M.; Wildermuth, Stefan

    2007-01-01

    Potential roughness has been reported to severely impair experiments in magnetic microtraps. We show that these obstacles can be overcome as we measure disorder potentials that are reduced by two orders of magnitude near lithographically patterned high-quality gold layers on semiconductor atom chip...

  14. Roughness vs. contrast in natural textures

    NARCIS (Netherlands)

    Van Egmond, R.; De Ridder, H.; Pappas, T.N.; Silva, P.M.

    2014-01-01

    We investigate the effect of contrast enhancement on the subjective roughness of visual textures. Our analysis is based on subjective experiments with seventeen images from the CUReT database in three variants: original, synthesized textures, and contrast-enhanced synthesized textures. In Experiment

  15. Distance upon contact : Determination from roughness profile

    NARCIS (Netherlands)

    van Zwol, P. J.; Svetovoy, V. B.; Palasantzas, G.

    2009-01-01

    The point at which two random rough surfaces make contact takes place at the contact of the highest asperities. The distance upon contact d(0) in the limit of zero load has crucial importance for determination of dispersive forces. Using gold films as an example we demonstrate that for two parallel

  16. The location- and depth-dependent mechanical response of the human cornea under shear loading.

    Science.gov (United States)

    Sloan, Stephen R; Khalifa, Yousuf M; Buckley, Mark R

    2014-10-30

    To characterize the depth-dependent shear modulus of the central and peripheral human cornea along the superior-inferior and nasal-temporal directions with a high spatial resolution. Cylindrical explants from the central and peripheral corneas of 10 human donors were subjected to a 5% shear strain along the superior-inferior and nasal-temporal directions using a microscope-mounted mechanical testing device. Depth-dependent shear strain and shear modulus were computed through force measurements and displacement tracking. The shear modulus G of the human cornea varied continuously with depth, with a maximum occurring roughly 25% of the way from the anterior surface to the posterior surface. G also varied with direction in the superior region and (at some depths) was significantly higher for superior-inferior shear loading. In the anterior half of the cornea, the shear modulus along the nasal-temporal direction (GNT) did not vary with location; however, the superior region had significantly higher GNT in posterior cornea. In contrast, the shear modulus along the superior-inferior direction (GSI) was independent of location at all depths. This study demonstrates that the peak shear modulus of the human cornea occurs at a substantial distance within the corneal stroma. Depth-dependent differences between central and peripheral cornea possibly reflect the location-dependent mechanical environment of the cornea. Moreover, the cornea is not a transverse isotropic material, and must be characterized by more than a single shear modulus due to its dependence on loading direction. The material properties measured in this study are critical for developing accurate mechanical models to predict the vision-threatening morphological changes that can occur in the cornea. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  17. On the levitation force in horizontal core-annular flow with a large viscosity ratio and small density ratio

    NARCIS (Netherlands)

    Ooms, G.; Pourquie, M.J.B.M.; Beerens, J.C.

    2013-01-01

    A numerical study has been made of horizontal core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe. Special attention is paid to the question how the buoyancy force on the core, caused by a density difference between

  18. Residual turbulence from velocity shear stabilized interchange instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Hung, C. P.; Hassam, A. B. [University of Maryland at College Park, College Park, Maryland 20742 (United States)

    2013-01-15

    The stabilizing effect of velocity shear on the macroscopic, broad bandwidth, ideal interchange instability is studied in linear and nonlinear regimes. A 2D dissipative magnetohydrodynamic (MHD) code is employed to simulate the system. For a given flow shear, V Prime , linear growth rates are shown to be suppressed to below the shear-free level at both the small and large wavelengths. With increasing V Prime , the unstable band in wavenumber-space shrinks so that the peak growth results for modes that correspond to relatively high wavenumbers, on the scale of the density gradient. In the nonlinear turbulent steady state, a similar turbulent spectrum obtains, and the convection cells are roughly circular. In addition, the density fluctuation level and the degree of flattening of the initial inverted density profile are found to decrease as V Prime increases; in fact, unstable modes are almost completely stabilized and the density profile reverts to laminar when V Prime is a few times the classic interchange growth rate. Moreover, the turbulent particle flux diminishes with increasing velocity shear such that all the flux is carried by the classical diffusive flux in the asymptotic limit. The simulations are compared with measurements of magnetic fluctuations from the Maryland Centrifugal Experiment, MCX, which investigated interchange modes in the presence of velocity shear. The experimental spectral data, taken in the plasma edge, are in general agreement with the numerical data obtained in higher viscosity simulations for which the level of viscosity is chosen consistent with MCX Reynolds numbers at the edge. In particular, the residual turbulence in both cases is dominated by elongated convection cells. Finally, concomitant Kelvin-Helmholtz instabilities in the system are also examined. Complete stability to interchanges is obtained only in the parameter space wherein the generalized Rayleigh inflexion theorem is satisfied.

  19. Influence of packing density and surface roughness of vertically-aligned carbon nanotubes on adhesive properties of gecko-inspired mimetics.

    Science.gov (United States)

    Chen, Bingan; Zhong, Guofang; Oppenheimer, Pola Goldberg; Zhang, Can; Tornatzky, Hans; Esconjauregui, Santiago; Hofmann, Stephan; Robertson, John

    2015-02-18

    We have systematically studied the macroscopic adhesive properties of vertically aligned nanotube arrays with various packing density and roughness. Using a tensile setup in shear and normal adhesion, we find that there exists a maximum packing density for nanotube arrays to have adhesive properties. Too highly packed tubes do not offer intertube space for tube bending and side-wall contact to surfaces, thus exhibiting no adhesive properties. Likewise, we also show that the surface roughness of the arrays strongly influences the adhesion properties and the reusability of the tubes. Increasing the surface roughness of the array strengthens the adhesion in the normal direction, but weakens it in the shear direction. Altogether, these results allow progress toward mimicking the gecko's vertical mobility.

  20. Influence of random roughness on cantilever resonance frequency

    OpenAIRE

    Ergincan, O.; Palasantzas, G.

    2010-01-01

    In this paper we investigate the influence of random roughness on the oscillation frequency of cantilevers coated with thin film overlayers. First the theory expressions for the roughness-induced frequency shift are derived using the cantilever equation of motion. Subsequently it is shown that the roughness induced shift depends on the particular roughness parameters, assuming the general case of self-affine rough surfaces for the overlayer film, the material properties of the overlayer film,...

  1. Shear viscosity of an ordering latex suspension

    NARCIS (Netherlands)

    van der Vorst, A.M.; van der Vorst, B.; van den Ende, Henricus T.M.; Aelmans, N.J.J.; Mellema, J.

    1997-01-01

    The shear viscosity of a latex which is ordered at rest is studied as a function of the shear rate and volume fraction. At low shear rates and for moderate to high volume fractions, the flow curves show dynamic yield behavior which disappears below a volume fraction of 8%. At high shear rates, the

  2. Experimental observation of shear thickening oscillation

    DEFF Research Database (Denmark)

    Nagahiro, Shin-ichiro; Nakanishi, Hiizu; Mitarai, Namiko

    2013-01-01

    We report experimental observations of the shear thickening oscillation, i.e. the spontaneous macroscopic oscillation in the shear flow of severe shear thickening fluid. Using a density-matched starch-water mixture, in the cylindrical shear flow of a few centimeters flow width, we observed...

  3. Effect of roughness on the conductivity of semiconducting thin films/quantum wells with double rough boundaries

    NARCIS (Netherlands)

    Palasantzas, G; De Hosson, JTM

    2003-01-01

    We have investigated the influence of surface/interface roughness on the electrical conductivity in semiconducting thin films/quantum wells with double self-affine rough interface boundaries. The self-affine boundary roughness is characterized by the roughness exponent H, the in-plane correlation

  4. Tactile perception of the roughness of the end of a tool: what role does tool handle roughness play?

    Science.gov (United States)

    Zampini, Massimiliano; Mawhinney, Sara; Spence, Charles

    2006-06-12

    We investigated whether the perceived roughness of the end of a tool is influenced by the texture of the handle used to hold it. Participants rated the roughness of the ends (caps) of a series of tools by rubbing them along their forearm, and indicated the perceived roughness of the tool's cap by means of an anchored visual scale. The caps of the tools had one of eight different levels of roughness varying from very smooth (sample 1) to very rough (sample 8). The participants held the tool handle in one hand while rubbing the cap of the tool against their contralateral forearm. The tool handle was either smooth (similar in smoothness to sample 1) or else very rough (matched in roughness to sample 8). Overall, participants were remarkably good at ignoring the roughness of the tool's handle when discriminating the roughness of the tool's cap. Nevertheless, the roughness of the tool handle was shown to modulate roughness judgments concerning the tool cap under certain conditions: in particular, tool caps at the rougher end of the scale (6 and 7) were rated as being significantly less rough when the participants held tools with a rough handle than when they held tools with a smooth handle. Our results therefore demonstrate a small but significant effect of the roughness of the handle of a tool on the perceived roughness of its cap.

  5. Focusing of Shear Shock Waves

    Science.gov (United States)

    Giammarinaro, Bruno; Espíndola, David; Coulouvrat, François; Pinton, Gianmarco

    2018-01-01

    Focusing is a ubiquitous way to transform waves. Recently, a new type of shock wave has been observed experimentally with high-frame-rate ultrasound: shear shock waves in soft solids. These strongly nonlinear waves are characterized by a high Mach number, because the shear wave velocity is much slower, by 3 orders of magnitude, than the longitudinal wave velocity. Furthermore, these waves have a unique cubic nonlinearity which generates only odd harmonics. Unlike longitudinal waves for which only compressional shocks are possible, shear waves exhibit cubic nonlinearities which can generate positive and negative shocks. Here we present the experimental observation of shear shock wave focusing, generated by the vertical motion of a solid cylinder section embedded in a soft gelatin-graphite phantom to induce linearly vertically polarized motion. Raw ultrasound data from high-frame-rate (7692 images per second) acquisitions in combination with algorithms that are tuned to detect small displacements (approximately 1 μ m ) are used to generate quantitative movies of gel motion. The features of shear shock wave focusing are analyzed by comparing experimental observations with numerical simulations of a retarded-time elastodynamic equation with cubic nonlinearities and empirical attenuation laws for soft solids.

  6. Displacement of one Newtonian fluid by another: density effects in axial annular flow

    DEFF Research Database (Denmark)

    Szabo, Peter; Hassager, Ole

    1997-01-01

    The arbitrary Lagrange-Euler (ALE) finite elementtechnique is used to simulate 3D displacement oftwo immiscible Newtonian fluids in vertical annular wells. For equally viscous fluids the effect of distinct fluid densities is investigated in the region of low to intermediate Reynolds numbers. Comp......, the efficiency of the displacement is analysed for various flow situations....

  7. Non-Newtonian fluid flow in annular pipes and entropy generation ...

    Indian Academy of Sciences (India)

    Non-Newtonian fluid flow in annular pipes is considered and the entropy generation due to fluid friction and heat transfer in them is formulated. ... Technical Education Faculty, Afyon Kocatepe University, Afyon, Turkey; Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, ...

  8. Experimental critical parameters of enriched uranium solution in annular tank geometries

    Energy Technology Data Exchange (ETDEWEB)

    Rothe, R.E.

    1996-04-01

    A total of 61 critical configurations are reported for experiments involving various combinations of annular tanks into which enriched uranium solution was pumped. These experiments were performed at two widely separated times in the 1980s under two programs at the Rocky Flats Plant`s Critical Mass Laboratory. The uranyl nitrate solution contained about 370 g of uranium per liter, but this concentration varied a little over the duration of the studies. The uranium was enriched to about 93% [sup 235]U. All tanks were typical of sizes commonly found in nuclear production plants. They were about 2 m tall and ranged in diameter from 0.6 m to 1.5 m. Annular thicknesses and conditions of neutron reflection, moderation, and absorption were such that criticality would be achieved with these dimensions. Only 13 of the entire set of 74 experiments proved to be subcritical when tanks were completely filled with solution. Single tanks of several radial thicknesses were studied as well as small line arrays (1 x 2 and 1 x 3) of annular tanks. Many systems were reflected on four sides and the bottom by concrete, but none were reflected from above. Many experiments also contained materials within and outside the annular regions that contained strong neutron absorbers. One program had such a thick external moderator/absorber combination that no reflector was used at all.

  9. Quench-induced trapping of magnetic flux in annular Josephson junctions

    DEFF Research Database (Denmark)

    Aarøe, Morten; Monaco, R.; Rivers, R.

    2008-01-01

    The aim of the project is to investigate spontaneous symmetry breaking in non-adiabatic phase transitions (Kibble-Zurek processes). A long and narrow annular Josephson tunnel junction is subjected to repeated thermal quenches through the normal-superconducting transition. The quench rate is varied...

  10. Droplets in annular-dispersed gas-liquid pipe-flows

    NARCIS (Netherlands)

    Van 't Westende, J.M.C.

    2008-01-01

    Annular-dispersed gas-liquid pipe-flows are commonly encountered in many industrial applications, and have already been studied for many decades. However, due to the great complexity of this type of flow, there are still many phenomena that are poorly understood. The aim of this thesis is to shed

  11. A comparison between numerical predictions and theoretical and experimental results for laminar core-annular flow

    NARCIS (Netherlands)

    Beerens, J.C.; Ooms, G.; Pourquie, M.J.B.M.; Westerweel, J.

    2014-01-01

    high-viscosity liquid core surrounded by a laminar low-viscosity liquid annular layer through a vertical pipe. The numerical results are compared with theoretical results from linear stability calculations and with experimental data. The comparison is good and the general conclusion of our study is

  12. Restart time correlation for core annular flow in pipeline lubrication of high-viscous oil

    National Research Council Canada - National Science Library

    Livinus, Aniefiok; Yeung, Hoi; Lao, Liyun

    ... in a 5.5-m-long PVC horizontal pipe with internal diameter of 26 mm are first presented. A new correlation for the prediction of the restart time of a shutdown core annular flow line is then formulated...

  13. Annular Electric Discharge as an Initiator of Combustion in Supersonic Flow

    Science.gov (United States)

    2009-02-01

    an annular multielectrode system placed inside the chamber. This discharger is a system of insulated ring electrodes (titanium, stainless steel...The caloric and thermic equations of state for the mixture are as follows: where T is the mixture temperature, iμ is the molar mass of the ith

  14. Quasi-static transient thermal stresses in a thick annular disc

    Indian Academy of Sciences (India)

    thermal stresses in annular fins with temperature-dependent conductivity under periodic heat transfer boundary condition is analysed by the Adomians decomposition method. ... where k is the thermal diffusivity of the material of the disc. The displacement function in the cylindrical coordinate system are represented by the.

  15. Experimental investigation of three-dimensional flow structures in annular swirling jets

    NARCIS (Netherlands)

    Percin, M.; Vanierschot, M.; Van Oudheusden, B.W.

    2015-01-01

    Annular jet flows are of practical interest in view of their occurrence in many industrial applications in the context of bluff-body combustors [1]. They feature different complex flow characteristics despite their simple geometry: a central recirculation zone (CRZ) as a result of flow separation

  16. Analysis of the pressure fields in a swirling annular jet flow

    NARCIS (Netherlands)

    Perçin, M.; Vanierschot, M.; van Oudheusden, B.W.

    2017-01-01

    In this paper, we investigate the flow structures and pressure fields of a free annular swirling jet flow undergoing vortex breakdown. The flow field is analyzed by means of time-resolved tomographic particle image velocimetry measurements, which enable the reconstruction of the three-dimensional

  17. Panoramic optical annular staring inspection system for evaluating the inner surface of a pipe

    Science.gov (United States)

    Zhao, Liefeng; Feng, Huajun; Bai, Jian; Jin, Hao

    2008-01-01

    There should be flaws and defects on the inner surface during the producing period of a pipe, as well as contaminations and corrosions during the using period of it. A corresponding panoramic optical annular staring inspection system has been developed. It requires no rotating mechanism to exam the whole circumference of a cross section of the inner pipe surface at once, which results high speed inspection. There are two main subsystems in this inspection system, the panoramic optical annular staring imaging subsystem and driving robot subsystem. The Flat Cylinder Perspective (FCP) is the principle to image a panoramic annular view to a flat imagery, i.e. a cylinder of vision imaged is flat. Our imaging subsystem includes a panoramic annular lens (PAL), which is critical and used to implement the FCP, a series of image rotation lenses, a charge-coupled device (CCD) camera, and an illuminating light-emitting diode (LED) ring. The CCD camera sending the signal to a personal computer (PC) via VGA signal results a real time inspection. The driving robot subsystem is a fine designed complicated mechanism including a subassembly of stepper motor. It can drive the inspection system forward and backward continuously in the pipe along the axial direction. The experimental system reported in this paper has the following specifications: average detection resolution of 0.5 mm at the circumference direction and 1.0 mm at the axial direction of a pipe, and inspection speed of 15 mm/s.

  18. Bifurcation and chaos in a dc-driven long annular Josephson junction

    DEFF Research Database (Denmark)

    Grnbech-Jensen, N.; Lomdahl, Peter S.; Samuelsen, Mogens Rugholm

    1991-01-01

    Simulations of long annular Josephson junctions in a static magnetic field show that in large regions of bias current the system can exhibit a period-doubling bifurcation route to chaos. This is in contrast to previously studied Josephson-junction systems where chaotic behavior has primarily been...

  19. LABORATORY AND NUMERICAL INVESTIGATIONS OF RESIDENCE TIME DISTRIBUTION OF FLUIDS IN LAMINAR FLOW STIRRED ANNULAR PHOTOREACTOR

    Science.gov (United States)

    Laboratory and Numerical Investigations of Residence Time Distribution of Fluids in Laminar Flow Stirred Annular PhotoreactorE. Sahle-Demessie1, Siefu Bekele2, U. R. Pillai11U.S. EPA, National Risk Management Research LaboratorySustainable Technology Division,...

  20. Response of an annular electrostatic probe for a right cylindrical spacer

    DEFF Research Database (Denmark)

    Johansson, Torben; MacAllister, I. W.

    2002-01-01

    The response of an annular electrostatic probe mounted in an electrode is examined with reference to a right cylindrical spacer. The study involves using the probe λ function to derive characteristic parameters. These parameters enable the response of the probe to different charge distributions...

  1. A Case of Erythema Annulare Centrifigum with Sjögren Syndrome

    Directory of Open Access Journals (Sweden)

    İlgen Ertam

    2010-03-01

    Full Text Available Erythema annulare centrifigum is a dermatose which is frequently seen in adults. It is characterized by erythematous lesions which spread asymmetrically to periphery and have a collarette desquamation. Although infection, tumor, food allergy, drug reaction can play a role in the aetiology, most of the cases are idiopathic. A forty-nine years old, female patient presented to our clinic with erythematous lesions on both of her lower extremities. Six weeks prior to her referral, she treated with quinine for Sjogren syndrome. She had a diagnosis of granuloma annulare in her personal history. There was no significance in her family history. In dermatologic examination; annular erythematous plaques and collarette desquamation were detected on lower extremities. Histopathologic examination of the lesional biopsy specimen revealed focal spongiosis in the epidermis, dermal oedema, vascular proliferation and perivascular infiltration of lymphocytes, eosinophils and histiocytes. In the laboratory examination; blood count, liver and kidney function tests, sedimentation, C-reactive protein was normal. Rheumatoid factor was 30. Antinuclear antibody was 1/640 granular pattern. A case of erythema annulare centrifigum with Sjögren Syndrome is discussed with the other skin findings of the disease.

  2. A parametric study on the growth of yield front in rotating annular disks

    African Journals Online (AJOL)

    user

    A parametric study on the growth of yield front in rotating annular disks. Shubhankar Bhowmick. 1. , Dipten Misra. 2 and Kashi Nath Saha. 3. 1 Department of Mechanical Engineering, National Institute of Technology, Raipur 492010, India. 2, 3 Department of Mechanical Engineering, Jadavpur University, Kolkata 700032, ...

  3. A parametric study on the growth of yield front in rotating annular disks

    African Journals Online (AJOL)

    The growth of elastic-plastic front under post-elastic conditions in high speed rotating annular disks having exponential and parabolic geometry variation is investigated in the present study. The problem is addressed in post-elastic regime through an extension of variational method based on von-Mises yield criterion and ...

  4. Annular Protofibrils Are a Structurally and Functionally Distinct Type of Amyloid Oligomer*

    OpenAIRE

    Kayed, Rakez; Pensalfini, Anna; Margol, Larry; Sokolov, Yuri; Sarsoza, Floyd; Head, Elizabeth; Hall, James; Glabe, Charles

    2009-01-01

    Amyloid oligomers are believed to play causal roles in several types of amyloid-related neurodegenerative diseases. Several different types of amyloid oligomers have been reported that differ in morphology, size, or toxicity, raising the question of the pathological significance and structural relationships between different amyloid oligomers. Annular protofibrils (APFs) have been described in oligomer preparations of many different amyloidogenic proteins and peptides ...

  5. The annular gap model for γ-ray emission from young and millisecond pulsars

    Science.gov (United States)

    Du, Y. J.; Qiao, G. J.; Han, J. L.; Lee, K. J.; Xu, R. X.

    2010-08-01

    Pulsed high-energy radiation from pulsars is not yet completely understood. In this paper, we use the 3D self-consistent annular gap model to study light curves for both young and millisecond pulsars (MSPs) observed by the Fermi Gamma-ray Space Telescope. The annular gap can generate high-energy emission for short-period pulsars. The annular gap regions are so large that they have enough electric potential drop to accelerate charged particles to produce γ-ray photons. For young pulsars, the emission region is from the neutron star surface to about half of the light cylinder radius, and the peak emissivity is in the vicinity of the null charge surface. The emission region for the millisecond pulsars is located much lower than that of the young pulsars. The higher energy γ-ray emission comes from higher altitudes in the magnetosphere. We present the simulated light curves for three young pulsars (the Crab, the Vela and the Geminga) and three millisecond pulsars (PSR J0030+0451, PSR J0218+4232 and PSR J0437-3715) using the annular gap model. Our simulations can reproduce the main properties of the observed light curves.

  6. Response of an annular electrostatic probe for a planar dielectric spacer: II

    DEFF Research Database (Denmark)

    Johansson, Torben; McAllister, Iain Wilson

    2004-01-01

    The response of annular electrostatic probes mounted in an electrode is examined with reference to a planar dielectric spacer. On this occasion, the presence of a high-voltage point electrode is included in the system geometry. The study involves using the probe λ function to derive characteristic...

  7. Digital flexor sheath: repair and reconstruction of the annular pulleys and membranous sheath.

    Science.gov (United States)

    Seiler, J G; Leversedge, F J

    2000-01-01

    Rupture or transection of the digital pulley may necessitate repair or reconstruction to treat symptomatic flexor tendon bowstringing. When reconstruction is necessary, intrasynovial tendon grafts may provide superior gliding characteristics when compared with traditional extrasynovial tendon grafts. Lacerations of the membranous portion of the digital sheath and of noncritical annular pulleys usually do not require operative repair.

  8. Repigmentation of gray hair in lesions of annular elastolytic giant cell granuloma.

    Science.gov (United States)

    Fernandez-Flores, Angel; Manjon, Jose A

    2015-07-01

    Hair pigmentation is a complex phenomenon that involves many hormones, neurotransmitters, cytokines, growth factors, eicosanoids, cyclic nucleotides, nutrients, and a physicochemical milieu. We report a case of repigmentation of gray hairs in lesions of annular elastolytic giant cell granuloma (AEGCG) on the scalp of a 67-year-old man.

  9. The importance of strain localisation in shear zones

    Science.gov (United States)

    Bons, Paul D.; Finch, Melanie; Gomez-Rivas, Enrique; Griera, Albert; Llorens, Maria-Gema; Steinbach, Florian; Weikusat, Ilka

    2016-04-01

    The occurrence of various types of shear bands (C, C', C'') in shear zones indicate that heterogeneity of strain is common in strongly deformed rocks. However, the importance of strain localisation is difficult to ascertain if suitable strain markers are lacking, which is usually the case. Numerical modelling with the finite-element method has so far not given much insight in the development of shear bands. We suggest that this is not only because the modelled strains are often not high enough, but also because this technique (that usually assumes isotropic material properties within elements) does not properly incorporate mineral deformation behaviour. We simulated high-strain, simple-shear deformation in single- and polyphase materials with a full-field theory (FFT) model coupled to the Elle modelling platform (www.elle.ws; Lebensohn 2001; Bons et al. 2008). The FFT-approach simulates visco-plastic deformation by dislocation glide, taking into account the different available slip systems and their critical resolved shear stresses in relations to the applied stresses. Griera et al. (2011; 2013) have shown that this approach is particularly well suited for strongly anisotropic minerals, such as mica and ice Ih (Llorens 2015). We modelled single- and polyphase composites of minerals with different anisotropies and strengths, roughly equivalent to minerals such as ice Ih, mica, quartz and feldspar. Single-phase polycrystalline aggregates show distinct heterogeneity of strain rate, especially in case of ice Ih, which is mechanically close to mica (see also Griera et al. 2015). Finite strain distributions are heterogeneous as well, but the patterns may differ from that of the strain rate distribution. Dynamic recrystallisation, however, usually masks any strain and strain rate localisation (Llorens 2015). In case of polyphase aggregates, equivalent to e.g. a granite, we observe extensive localisation in both syn- and antithetic shear bands. The antithetic shear bands

  10. Rough primes and rough conversations: evidence for a modality-specific basis to mental metaphors.

    Science.gov (United States)

    Schaefer, Michael; Denke, Claudia; Heinze, Hans-Jochen; Rotte, Michael

    2014-11-01

    How does our brain organize knowledge? Traditional theories assume that our knowledge is represented abstractly in an amodal conceptual network of formal logic symbols. The theory of embodied cognition challenges this view and argues that conceptual representations that constitute our knowledge are grounded in sensory and motor experiences. We tested this hypothesis by examining how the concept of social coordination is grounded metaphorically in the tactile sensation of roughness. Participants experienced rough or smooth touch before being asked to judge an ambiguous social interaction. Results revealed that rough touch made social interactions appear more difficult and adversarial, consistent with the rough metaphor. This impact of tactile cues on social impressions was accompanied by a network including primary and secondary somatosensory cortices, amygdala, hippocampus and inferior prefrontal cortex. Thus, the roughness of tactile stimulation affected metaphor-relevant (but not metaphor-irrelevant) behavioral and neural responses. Receiving touch from a rough object seems to trigger the application of associated ontological concepts (or scaffolds) even for unrelated people and situations (but not to unrelated or more general feelings). Since this priming was based on somatosensory brain areas, our results provide support for the theory that sensorimotor grounding is intrinsic to cognitive processes. © The Author (2013). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  11. Offshore Wind Power at Rough Sea

    DEFF Research Database (Denmark)

    Petersen, Kristian Rasmus; Madsen, Erik Skov; Bilberg, Arne

    2013-01-01

    This study compare the current operations and maintenance issues of one offshore wind park at very rough sea conditions and two onshore wind parks. Through a detailed data analysis and case studies this study identifies how improvements have been made in maintenance of large wind turbines. Howeve......, the study has also revealed the need for new maintenance models including a shift from breakdown and preventive maintenances and towards more predictive maintenance to reduce the cost of energy for offshore wind energy installations in the future.......This study compare the current operations and maintenance issues of one offshore wind park at very rough sea conditions and two onshore wind parks. Through a detailed data analysis and case studies this study identifies how improvements have been made in maintenance of large wind turbines. However...

  12. Analysis of accuracy in photogrammetric roughness measurements

    Science.gov (United States)

    Olkowicz, Marcin; Dąbrowski, Marcin; Pluymakers, Anne

    2017-04-01

    Regarding permeability, one of the most important features of shale gas reservoirs is the effective aperture of cracks opened during hydraulic fracturing, both propped and unpropped. In a propped fracture, the aperture is controlled mostly by proppant size and its embedment, and fracture surface roughness only has a minor influence. In contrast, in an unpropped fracture aperture is controlled by the fracture roughness and the wall displacement. To measure fracture surface roughness, we have used the photogrammetric method since it is time- and cost-efficient. To estimate the accuracy of this method we compare the photogrammetric measurements with reference measurements taken with a White Light Interferometer (WLI). Our photogrammetric setup is based on high resolution 50 Mpx camera combined with a focus stacking technique. The first step for photogrammetric measurements is to determine the optimal camera positions and lighting. We compare multiple scans of one sample, taken with different settings of lighting and camera positions, with the reference WLI measurement. The second step is to perform measurements of all studied fractures with the parameters that produced the best results in the first step. To compare photogrammetric and WLI measurements we regrid both data sets onto a regular 10 μm grid and determined the best fit, followed by a calculation of the difference between the measurements. The first results of the comparison show that for 90 % of measured points the absolute vertical distance between WLI and photogrammetry is less than 10 μm, while the mean absolute vertical distance is 5 μm. This proves that our setup can be used for fracture roughness measurements in shales.

  13. Roughness Length Variability over Heterogeneous Surfaces

    Science.gov (United States)

    2010-03-01

    By this definition , roughness length, although defined at a specific point , substantially depends upon the morphology of the surface in some...circulations at Cape Canaveral have been conducted in situ using Doppler radar and cloud photogrammetry (Wakimoto and Atkins 1993); observations (Reed 1979...the sea-breeze front during CaPE. part I: single-Doppler, satellite, and cloud photogrammetry analysis. Mon. Wea. Rev., 122, 1092–1114. Wang, Q

  14. Spectrophotometric Examination of Rough Print Surfaces

    OpenAIRE

    Erzsébet Novotny

    2011-01-01

    The objective was to assess the impact of the surface texture of individual creative paper types (coated or patterned)on the quality of printing and to identify to what extent the various creative paper types require specific types ofspectrophotometers. We used stereomicroscopic images to illustrate unprinted and printed surfaces of creative papertypes. Surface roughness was measured to obtain data on the unevenness of surfaces. Spectrophotometric tests wereused to select the most suitable sp...

  15. Rough – Granular Computing knowledge discovery models

    Directory of Open Access Journals (Sweden)

    Mohammed M. Eissa

    2016-11-01

    Full Text Available Medical domain has become one of the most important areas of research in order to richness huge amounts of medical information about the symptoms of diseases and how to distinguish between them to diagnose it correctly. Knowledge discovery models play vital role in refinement and mining of medical indicators to help medical experts to settle treatment decisions. This paper introduces four hybrid Rough – Granular Computing knowledge discovery models based on Rough Sets Theory, Artificial Neural Networks, Genetic Algorithm and Rough Mereology Theory. A comparative analysis of various knowledge discovery models that use different knowledge discovery techniques for data pre-processing, reduction, and data mining supports medical experts to extract the main medical indicators, to reduce the misdiagnosis rates and to improve decision-making for medical diagnosis and treatment. The proposed models utilized two medical datasets: Coronary Heart Disease dataset and Hepatitis C Virus dataset. The main purpose of this paper was to explore and evaluate the proposed models based on Granular Computing methodology for knowledge extraction according to different evaluation criteria for classification of medical datasets. Another purpose is to make enhancement in the frame of KDD processes for supervised learning using Granular Computing methodology.

  16. Characterizing overwater roughness Reynolds number during hurricanes

    Science.gov (United States)

    Hsu, S. A.; Shen, Hui; He, Yijun

    2017-11-01

    The Reynolds number, which is the dimensionless ratio of the inertial force to the viscous force, is of great importance in the theory of hydrodynamic stability and the origin of turbulence. To investigate aerodynamically rough flow over a wind sea, pertinent measurements of wind and wave parameters from three data buoys during Hurricanes Kate, Lili, Ivan, Katrina, Rita, and Wilma are analyzed. It is demonstrated that wind seas prevail when the wind speed at 10 m and the wave steepness exceed 9 m s-1 and 0.020, respectively. It is found that using a power law the roughness Reynolds number is statistically significantly related to the significant wave height instead of the wind speed as used in the literature. The reason for this characterization is to avoid any self-correlation between Reynolds number and the wind speed. It is found that although most values of R_{*} were below 500, they could reach to approximately 1000 near the radius of maximum wind. It is shown that, when the significant wave height exceeds approximately 2 m in a wind sea, the air flow over that wind sea is already under the fully rough condition. Further analysis of simultaneous measurements of wind and wave parameters using the logarithmic law indicates that the estimated overwater friction velocity is consistent with other methods including the direct (eddy-covariance flux) measurements, the atmospheric vorticity approach, and the sea-surface current measurements during four slow moving super typhoons with wind speed up to 70 m s-1.

  17. ROUGHNESS ANALYSIS OF VARIOUSLY POLISHED NIOBIUM SURFACES

    Energy Technology Data Exchange (ETDEWEB)

    Ribeill, G.; Reece, C.

    2008-01-01

    Niobium superconducting radio frequency (SRF) cavities have gained widespread use in accelerator systems. It has been shown that surface roughness is a determining factor in the cavities’ effi ciency and maximum accelerating potential achievable through this technology. Irregularities in the surface can lead to spot heating, undesirable local electrical fi eld enhancement and electron multipacting. Surface quality is typically ensured through the use of acid etching in a Buffered Chemical Polish (BCP) bath and electropolishing (EP). In this study, the effects of these techniques on surface morphology have been investigated in depth. The surface of niobium samples polished using different combinations of these techniques has been characterized through atomic force microscopy (AFM) and stylus profi lometry across a range of length scales. The surface morphology was analyzed using spectral techniques to determine roughness and characteristic dimensions. Experimentation has shown that this method is a valuable tool that provides quantitative information about surface roughness at different length scales. It has demonstrated that light BCP pretreatment and lower electrolyte temperature favors a smoother electropolish. These results will allow for the design of a superior polishing process for niobium SRF cavities and therefore increased accelerator operating effi ciency and power.

  18. The limits of cosmic shear

    Science.gov (United States)

    Kitching, Thomas D.; Alsing, Justin; Heavens, Alan F.; Jimenez, Raul; McEwen, Jason D.; Verde, Licia

    2017-08-01

    In this paper, we discuss the commonly used limiting cases, or approximations, for two-point cosmic-shear statistics. We discuss the most prominent assumptions in this statistic: the flat-sky (small angle limit), the Limber (Bessel-to-delta function limit) and the Hankel transform (large ℓ-mode limit) approximations; that the vast majority of cosmic-shear results to date have used simultaneously. We find that the combined effect of these approximations can suppress power by ≳ 1 per cent on scales of ℓ ≲ 40. A fully non-approximated cosmic-shear study should use a spherical-sky, non-Limber-approximated power spectrum analysis and a transform involving Wigner small-d matrices in place of the Hankel transform. These effects, unaccounted for, would constitute at least 11 per cent of the total budget for systematic effects for a power spectrum analysis of a Euclid-like experiment; but they are unnecessary.

  19. Statistical Model of Extreme Shear

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Hansen, Kurt Schaldemose

    2004-01-01

    (PDF) of turbulence driven short-term extreme wind shear events, conditioned on the mean wind speed, for an arbitrary recurrence period. The model is based on an asymptotic expansion, and only a few and easily accessible parameters are needed as input. The model of the extreme PDF is supplemented...... by a model that, on a statistically consistent basis, describe the most likely spatial shape of an extreme wind shear event. Predictions from the model have been compared with results from an extreme value data analysis, based on a large number of high-sampled full-scale time series measurements...... are consistent, given the inevitabel uncertainties associated with model as well as with the extreme value data analysis. Keywords: Statistical model, extreme wind conditions, statistical analysis, turbulence, wind loading, statistical analysis, turbulence, wind loading, wind shear, wind turbines....

  20. An experimental study of single-phase and two-phase flow in annular helicoidal pipes

    Energy Technology Data Exchange (ETDEWEB)

    Xin, R.C.; Awwad, A.; Dong, Z.F.; Ebadian, M.A. [Florida International Univ., Miami, FL (United States). Hemispheric Center for Environmental Technology

    1996-12-31

    In this study, experimental investigations were conducted for single-phase and two-phase flow in annular helicoidal pipes with vertical and horizontal orientations using air and water as working fluids. Three test sections were tested. The outer diameters of the inner tube were 12.7 mm, 9.525 mm, and 6.35 mm, while the inner diameters of the outer tube were 21.18 mm, 15.748 mm, and 10.21 mm, respectively. The experiments were performed for superficial water Reynolds numbers in the range of 210--23,000 and superficial air Reynolds numbers in the range of 30--30,000. The effects of coil geometry and the flow rates of air and water on single-phase and two-phase flow pressure drop were experimentally investigated for annular helicoidal pipes. The data were correlated as the relationship of the pressure drop multiplier versus the Lockhart-Martinelli parameter for the two-phase flow. The average void fraction was also measured in the experiments by means of the quick acting valve method. Unlike two-phase flow in straight pipe, the pressure drop multiplier of two-phase flow in annular helicoidal pipe has been found to be dependent on the flow rate besides the Lockhart-Martinelli parameter for large pipe diameter in annular helicoidal pipe. The Lockhart-Martinelli correlation is not valid in the prediction. Correlations for two-phase flow in horizontal and vertical annular helicoidal pipe have been established for both single-phase and two-phase flow based on the present experimental data.

  1. Lacunarity study of speckle patterns produced by rough surfaces

    Science.gov (United States)

    Dias, M. R. B.; Dornelas, D.; Balthazar, W. F.; Huguenin, J. A. O.; da Silva, L.

    2017-11-01

    In this work we report on the study of Lacunarity of digital speckle patterns generated by rough surfaces. The study of Lacunarity of speckle patterns was performed on both static and moving rough surfaces. The results show that the Lacunarity is sensitive to the surface roughness, which suggests that it can be used to perform indirect measurement of surface roughness as well as to monitor defects, or variations of roughness, of metallic moving surfaces. Our results show the robustness of this statistical tool applied to speckle pattern in order to study surface roughness.

  2. A Note on the bottom shear stress in oscillatory planetary boundary layer flow

    Directory of Open Access Journals (Sweden)

    Dag Myrhaug

    1988-07-01

    Full Text Available A simple analytical theory is presented, which describes the motion in a turbulent oscillatory planetary boundary layer near a rough seabed using a two-layer, time-invariant eddy viscosity model. The bottom shear stress is outlined, and comparison is made with Pingree and Griffiths' (1974 measurements of turbulent tidal planetary boundary layer flow on the continental shelf south-west of Lands End, England.

  3. Shear resistance of beams based on the effective shear depth

    NARCIS (Netherlands)

    Pruijssers, A.F.

    1986-01-01

    Despite extensive experimental and theoretical studies the shear resistance of beams with longitudinal reinforcement is described by empirical expressions. A reliable empirical formula is derived by Rafla [10]. This formula is based on 442 experimental results. In this report no experiments are

  4. Statistical Investigation of the Effect of Process Parameters on the Shear Strength of Metal Adhesive Joints

    Science.gov (United States)

    Rajkumar, Goribidanur Rangappa; Krishna, Munishamaih; Narasimhamurthy, Hebbale Narayanrao; Keshavamurthy, Yalanabhalli Channegowda

    2017-06-01

    The objective of the work was to optimize sheet metal joining parameters such as adhesive material, adhesive thickness, adhesive overlap length and surface roughness for single lap joint of aluminium sheet shear strength using robust design. An orthogonal array, main effect plot, signal-to-noise ratio and analysis of variance were employed to investigate the shear strength of the joints. The statistical result shows vinyl ester is best candidate among other two polymers viz. epoxy and polyester due to its low viscosity value compared to other two polymers. The experiment results shows that the adhesive thickness 0.6 mm, overlap length 50 mm and surface roughness 2.12 µm for obtained maximum shear strength of Al sheet joints. The ANOVA result shows one of the most significant factors is overlap length which affect joint strength in addition to adhesive thickness, adhesive material, and surface roughness. A confirmation test was carried out as the optimal combination of parameters will not match with the any of the experiments in the orthogonal array.

  5. 3D surface roughness recreation and data processing of granitic rocks and claystones, potential host rocks for radioactive waste disposal

    Science.gov (United States)

    Buocz, Ildikó; Török, Ákos; Rozgonyi-Boissinot, Nikoletta

    2015-04-01

    The determination and modelling of the stability of rock slopes, tunnels, or underground spaces, i.e. radioactive waste disposal facilities, is an important task in engineering. The appropriate estimation of the mechanical parameters for a realistic description of the behaviour of rocks results in higher safety and more economic design. The failure of stability is primarily due to the shear failure of the rock masses along fractures and joints: therefore the correct determination of the shear strength is crucial. One of the most important parameters influencing the shear strength along rock joints is their surface roughness. Although the quantification of surface roughness has been an open question during the past century, several attempts have been made, starting with 2D and continuing with 3D measurements, to provide engineers with a method for determining shear strength numerically. As technology evolved, the 3D methods became more popular and several scientists started to investigate the surface properties through laser scanning and different photogrammetrical methods. This paper shows a photogrammetric method for the 3D digital recreation of joint surfaces of granitic rock and claystone, both potential host rocks for radioactive waste disposal. The rocks derived from Bátaapáti (South Hungary) and Mont Terri (North Switzerland) respectively. The samples are laboratory scaled specimens with an areal size of 50x50 mm. The software used is called ShapeMetrix3D, developed by 3GSM GmbH in Austria. The major steps of the creation of the 3D picture are presented, as well as the following data processing which leads to the quantification of the 3D surface roughness.

  6. On the levitation force in horizontal core-annular flow with a large viscosity ratio and small density ratio

    OpenAIRE

    Ooms, G.; Pourquie, M.J.B.M.; Beerens, J.C.

    2013-01-01

    A numerical study has been made of horizontal core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe. Special attention is paid to the question how the buoyancy force on the core, caused by a density difference between the core and the annular layer, is counterbalanced. The volume-of-fluid method is used to calculate the velocities and pressures in the two liquids. At the start of the calculation the core is in ...

  7. Knudsen self- and Fickian diffusion in rough nanoporous media

    NARCIS (Netherlands)

    Malek, K.; Coppens, M.O.

    2003-01-01

    The effect of pore surface roughness on Knudsen diffusion in nanoporous media is investigated by dynamic Monte Carlo simulations and analytical calculations. A conceptual difference is found between the roughness dependence of the macroscopic, transport diffusivity and the microscopic,

  8. Role of biofilm roughness and hydrodynamic conditions in Legionella pneumophila adhesion to and detachment from simulated drinking water biofilms.

    Science.gov (United States)

    Shen, Yun; Monroy, Guillermo L; Derlon, Nicolas; Janjaroen, Dao; Huang, Conghui; Morgenroth, Eberhard; Boppart, Stephen A; Ashbolt, Nicholas J; Liu, Wen-Tso; Nguyen, Thanh H

    2015-04-07

    Biofilms in drinking water distribution systems (DWDS) could exacerbate the persistence and associated risks of pathogenic Legionella pneumophila (L. pneumophila), thus raising human health concerns. However, mechanisms controlling adhesion and subsequent detachment of L. pneumophila associated with biofilms remain unclear. We determined the connection between L. pneumophila adhesion and subsequent detachment with biofilm physical structure characterization using optical coherence tomography (OCT) imaging technique. Analysis of the OCT images of multispecies biofilms grown under low nutrient condition up to 34 weeks revealed the lack of biofilm deformation even when these biofilms were exposed to flow velocity of 0.7 m/s, typical flow for DWDS. L. pneumophila adhesion on these biofilm under low flow velocity (0.007 m/s) positively correlated with biofilm roughness due to enlarged biofilm surface area and local flow conditions created by roughness asperities. The preadhered L. pneumophila on selected rough and smooth biofilms were found to detach when these biofilms were subjected to higher flow velocity. At the flow velocity of 0.1 and 0.3 m/s, the ratio of detached cell from the smooth biofilm surface was from 1.3 to 1.4 times higher than that from the rough biofilm surface, presumably because of the low shear stress zones near roughness asperities. This study determined that physical structure and local hydrodynamics control L. pneumophila adhesion to and detachment from simulated drinking water biofilm, thus it is the first step toward reducing the risk of L. pneumophila exposure and subsequent infections.

  9. Meniscal shear stress for punching

    NARCIS (Netherlands)

    Tuijthof, Gabrielle J. M.; Meulman, Hubert N.; Herder, Just L.; van Dijk, C. Niek

    2009-01-01

    Aim: Experimental determination of the shear stress for punching meniscal tissue. Methods: Meniscectomy (surgical treatment of a lesion of one of the menisci) is the most frequently performed arthroscopic procedure. The performance of a meniscectomy is not optimal with the currently available

  10. Modelling roughness evolution and debris production in faults using discrete particles

    Science.gov (United States)

    Mair, Karen; Abe, Steffen

    2017-04-01

    The frictional strength and stability (hence seismic potential) of faults in the brittle part of the crust is closely linked to fault roughness evolution and debris production during accumulated slip. The relevant processes may also control the dynamics of rock-slides, avalanches and sub glacial slip thus are of general interest in several fields. The quantitative characterisation of fault surfaces in the field (e.g. Candela et al. JGR, 2012) has helped build a picture of fault roughness across many orders of magnitude, however, since fault zones are generally not exposed during slip and gouge zones rarely preserved, the mechanical implications of evolving roughness and the important role of debris or gouge in fault zone evolution remain elusive. Here we investigate the interplay between fault roughness evolution and gouge production using 3D Discrete Element Method (DEM) Boundary Erosion Models. Our fault walls are composed of many particles or clusters stuck together with breakable bonds. When bond strength is exceeded, the walls fracture to produce erodible boundaries and a debris filled fault zone that evolves with accumulated slip. We slide two initially bare surfaces past each other under a range of normal stresses, tracking the evolving topography of eroded fault walls, the granular debris generated and the associated mechanical behaviour. The development of slip parallel striations, reminiscent of those found in natural faults, are commonly observed, however often as transient rather than persistent features. At the higher normal stresses studied, we observe a two stage wear-like gouge production where an initial 'running-in' high production rate saturates as debris accumulates and separates the walls. As shear, and hence granular debris, accumulates, we see evidence of grain size based sorting in the granular layers. Wall roughness and friction mimic this stabilisation, highlighting a direct link between gouge processes, wall roughness evolution and

  11. Temperature-Dependent Effect of Boric Acid Additive on Surface Roughness and Wear Rate

    Science.gov (United States)

    Ekinci, Şerafettin

    Wear and friction hold an important place in engineering. Currently, scientific societies are struggling to control wear by means of studies on lubricants. Boric acid constitutes an important alternative with its good tribological properties similar to MO2S and graphite alongside with low environmental impacts. Boric acid can be used as a solid lubricant itself whereas it can be added or blended into mineral oils in order to yield better mechanical and tribological properties such as low shear stress due to the lamellar structure and low friction, wear and surface roughness rates. In this study, distinguishing from the literature, boric acid addition effect considering the temperature was investigated for the conventional ranges of internal combustion engines. Surface roughness, wear and friction coefficient values were used in order to determine tribological properties of boric acid as an environmentally friendly additive and mineral oil mixture in the present study. Wear experiments were conducted with a ball on disc experimental setup immersed in an oil reservoir at room temperature, 50∘C and 80∘C. The evolution of both the friction coefficient and wear behavior was determined under 10N load, at 2m/s sliding velocity and a total sliding distance of 9000m. Surface roughness was determined using atomic-force microscopy (AFM). Wear rate was calculated utilizing scanning electron microscope (SEM) visuals and data. The test results showed that wear resistance increased as the temperature increased, and friction coefficient decreased due to the presence of boric acid additive.

  12. Hourly wind profiler observations of the jet stream - Wind shear and pilot reports of turbulence

    Science.gov (United States)

    Syrett, William J.

    1991-01-01

    Hourly wind profiler observations of the jet stream are reported on the basis of over 400 hr of wind and temperature data taken during two prolonged jet stream passages over western and central Pennsylvania during mid-November 1986 and mid-January 1987. The mean wind speed profile with error bars for the 79 hr that the Crown radar was determined to be 'under' the jet stream is shown. A mean speed of 83 m/s for the period was found. A plot of wind shear for the hours of interest is given. Typically, the shear was at a maximum from 3 to 4 km below the level of maximum wind. Thus, an aircraft would have to fly through potentially rough air to reach the fuel savings and relative smoothness of flight at the jet stream level. A good correlation between pilot reports of turbulence and wind shear was found.

  13. Wave scattering from statistically rough surfaces

    CERN Document Server

    Bass, F G; ter Haar, D

    2013-01-01

    Wave Scattering from Statistically Rough Surfaces discusses the complications in radio physics and hydro-acoustics in relation to wave transmission under settings seen in nature. Some of the topics that are covered include radar and sonar, the effect of variations in topographic relief or ocean waves on the transmission of radio and sound waves, the reproduction of radio waves from the lower layers of the ionosphere, and the oscillations of signals within the earth-ionosphere waveguide. The book begins with some fundamental idea of wave transmission theory and the theory of random processes a

  14. Roughly isometric minimal immersions into Riemannian manifolds

    DEFF Research Database (Denmark)

    Markvorsen, Steen

    . In this talk we will mainly be concerned with {\\em{minimal}} isometric immersions of such geometrized approximations $(G, g)$ of $X$ into Riemannian manifolds $N$ with bounded curvature. When such an immersion exists, we will call it an $X$-web in $N$. Such webs admit a natural 'geometric' extension...... of the intrinsic combinatorial discrete Laplacian, and we will show that they share several analytic and geometric properties with their smooth (minimal submanifold) counterparts in $N$. The intrinsic properties thus obtained may hence serve as roughly invariant descriptors for the original metric space $X$....

  15. Simulation of chemical erosion in rough fractures.

    Science.gov (United States)

    Verberg, R; Ladd, A J C

    2002-05-01

    We report on numerical simulations of acid erosion in a fractured specimen of Carrara marble. The simulations combine two recent advances in lattice-Boltzmann methodology to accurately and efficiently calculate the velocity field in the pore space. A tracer diffusion algorithm was then used to calculate the distribution of reactants in the fracture, and the local erosion rate was obtained from the flux of tracer particles across the surfaces. Our results show that at large length scales, erosion leads to increased heterogeneity via channel formation, whereas at small length scales it tends to smooth out the roughness in the local aperture.

  16. Traceability of optical roughness measurements on polymers

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Gasparin, Stefania; Carli, Lorenzo

    2008-01-01

    -focus instrument, and a confocal microscope. Using stylus measurements as reference, parameter settings on the optical instruments were optimised and residual noise reduced by low pass filtering. Traceability of optical measurements could be established with expanded measuring uncertainties (k=2) of 4......An experimental investigation on surface roughness measurements on plastics was carried out with the objective of developing a methodology to achieve traceability of optical instruments. A ground steel surface and its replicas were measured using a stylus instrument, an optical auto......% for the auto-focus instrument and 10% for confocal microscope....

  17. Albedo over rough snow and ice surfaces

    Science.gov (United States)

    Lhermitte, S.; Abermann, J.; Kinnard, C.

    2014-06-01

    Both satellite and ground-based broadband albedo measurements over rough and complex terrain show several limitations concerning feasibility and representativeness. To assess these limitations and understand the effect of surface roughness on albedo, firstly, an intrasurface radiative transfer (ISRT) model is combined with albedo measurements over different penitente surfaces on Glaciar Tapado in the semi-arid Andes of northern Chile. Results of the ISRT model show effective albedo reductions over the penitentes up to 0.4 when comparing the rough surface albedo relative to the albedo of the flat surface. The magnitude of these reductions primarily depends on the opening angles of the penitentes, but the shape of the penitentes and spatial variability of the material albedo also play a major role. Secondly, the ISRT model is used to reveal the effect of using albedo measurements at a specific location (i.e., apparent albedo) to infer the true albedo of a penitente field (i.e., effective albedo). This effect is especially strong for narrow penitentes, resulting in sampling biases of up to ±0.05. The sampling biases are more pronounced when the sensor is low above the surface, but remain relatively constant throughout the day. Consequently, it is important to use a large number of samples at various places and/or to locate the sensor sufficiently high in order to avoid this sampling bias of surface albedo over rough surfaces. Thirdly, the temporal evolution of broadband albedo over a penitente-covered surface is analyzed to place the experiments and their uncertainty into a longer temporal context. Time series of albedo measurements at an automated weather station over two ablation seasons reveal that albedo decreases early in the ablation season. These decreases stabilize from February onwards with variations being caused by fresh snowfall events. The 2009/2010 and 2011/2012 seasons differ notably, where the latter shows lower albedo values caused by larger

  18. Rough sets selected methods and applications in management and engineering

    CERN Document Server

    Peters, Georg; Ślęzak, Dominik; Yao, Yiyu

    2012-01-01

    Introduced in the early 1980s, Rough Set Theory has become an important part of soft computing in the last 25 years. This book provides a practical, context-based analysis of rough set theory, with each chapter exploring a real-world application of Rough Sets.

  19. Roughness correction to the Casimir force beyond perturbation theory

    NARCIS (Netherlands)

    Broer, Wijnand; Palasantzas, George; Knoester, Jasper; Svetovoy, Vitaly B.

    Up to now there has been no reliable method to calculate the Casimir force when surface roughness becomes comparable with the separation between bodies. Statistical analysis of rough Au films demonstrates rare peaks with heights considerably larger than the root-mean-square (rms) roughness. These

  20. Procedure and applications of combined wheel/rail roughness measurement

    NARCIS (Netherlands)

    Dittrich, M.G.

    2009-01-01

    Wheel-rail roughness is known to be the main excitation source of railway rolling noise. Besides the already standardised method for direct roughness measurement, it is also possible to measure combined wheel-rail roughness from vertical railhead vibration during a train pass-by. This is a different

  1. ROMI 4.0: Updated Rough Mill Simulator

    Science.gov (United States)

    Timo Grueneberg; R. Edward Thomas; Urs. Buehlmann

    2012-01-01

    In the secondary hardwood industry, rough mills convert hardwood lumber into dimension parts for furniture, cabinets, and other wood products. ROMI 4.0, the US Department of Agriculture Forest Service's ROugh-MIll simulator, is a software package designed to simulate the cut-up of hardwood lumber in rough mills in such a way that a maximum possible component yield...

  2. Use of roughness maps in visualisation of surfaces

    DEFF Research Database (Denmark)

    Seitavuopio, Paulus; Rantanen, Jukka; Yliruusi, Jouko

    2005-01-01

    monohydrate, theophylline anhydrate, sodium chloride and potassium chloride. The roughness determinations were made by a laser profilometer. The new matrix method gives detailed roughness maps, which are able to show local variations in surface roughness values and provide an illustrative picture...

  3. Studying plastic shear localization in aluminum alloys under dynamic loading

    Science.gov (United States)

    Bilalov, D. A.; Sokovikov, M. A.; Chudinov, V. V.; Oborin, V. A.; Bayandin, Yu. V.; Terekhina, A. I.; Naimark, O. B.

    2016-12-01

    An experimental and theoretical study of plastic shear localization mechanisms observed under dynamic deformation using the shear-compression scheme on a Hopkinson-Kolsky bar has been carried out using specimens of AMg6 alloy. The mechanisms of plastic shear instability are associated with collective effects in the microshear ensemble in spatially localized areas. The lateral surface of the specimens was photographed in the real-time mode using a CEDIP Silver 450M high-speed infrared camera. The temperature distribution obtained at different times allowed us to trace the evolution of the localization of the plastic strain. Based on the equations that describe the effect of nonequilibrium transitions on the mechanisms of structural relaxation and plastic flow, numerical simulation of plastic shear localization has been performed. A numerical experiment relevant to the specimen-loading scheme was carried out using a system of constitutive equations that reflect the part of the structural relaxation mechanisms caused by the collective behavior of microshears with the autowave modes of the evolution of the localized plastic flow. Upon completion of the experiment, the specimens were subjected to microstructure analysis using a New View-5010 optical microscope-interferometer. After the dynamic deformation, the constancy of the Hurst exponent, which reflects the relationship between the behavior of defects and roughness induced by the defects on the surfaces of the specimens is observed in a wider range of spatial scales. These investigations revealed the distinctive features in the localization of the deformation followed by destruction to the script of the adiabatic shear. These features may be caused by the collective multiscale behavior of defects, which leads to a sharp decrease in the stress-relaxation time and, consequently, a localized plastic flow and generation of fracture nuclei in the form of adiabatic shear. Infrared scanning of the localization zone of the

  4. Wind shear procedures and the instrumentation

    Science.gov (United States)

    Melvin, W. W.

    1990-01-01

    The effect of pitch rate on abort landing caused by wind shear encounters is discussed. Optimal trajectories, airspeed, and wind shear warning systems are briefly discussed. The bulk of the presentation is in viewgraph form.

  5. Few thoughts on Mixing and Entrainment of Lock-Release Turbulent Dense Currents over Rough-Surfaces

    Science.gov (United States)

    Bhaganaagar, Kiran; NaraSimhaRao, Pavan

    2017-04-01

    Buoyancy driven density currents are the result of the intense turbulence exchanges that occur due to interaction of dense waters with surrounding ambient and calm waters in the ocean. E.g. in the basins of the Arctic continent shelves highly energetic and dissipative density current form due to mixing of cold, dense brine-enriched shelf waters with ambient lighter waters. Intense turbulence causes mixing, the mixed water mass descends down the continental slope. The eventual properties of the mixed water will dictate the deep-water mass. Hence, entrainment/mixing processes are central to oceanic thermohaline circulation. In spite of its importance, the entrainment and the mixing they undergo with overlying water is still not clear. In this talk, we focus on overcoming the challenges in calculating the entrainment over rough-surfaces. The analysis is conducted on lock-release density currents. A highly accurate direct numerical simulation and large eddy simulation solvers have been developed to simulate dense currents over range of rough-surfaces. A new method has been developed to calculate mixing in the head of the density-currents using principles of height-averaged density method. The results have revealed the shape of roughness elements and the standard deviation of the roughness height are the important metrics that influence the front velocity and front characteristics. Entrainment is significant in the head region of dense currents over uniform roughness, whereas for non-uniform rough surfaces, entrainment occurs throughout the current. These results have important implications in our current understanding of mixing in head region of the density current. Further, a relation has been established between the wall-shear stress and entrainment, and this has resulted in a new parameterization of the entrainment as function of the roughness metrics. This study will of be important consequence in improving the accuracy of parameterization of density currents in

  6. Tilting Shear Layers in Coastal Flows

    Science.gov (United States)

    2015-09-30

    term goals of this research are to explore the evolution of flows with strong horizontal shear and horizontal density gradients (see Figure 1). These...converting horizontal shear to vertical shear. The horizontal shear leads to the growth of vertical vortices that are subsequently tilted, stretched...small-scale flows influence the water properties within the lagoons and merge with the larger scale flows around the islands. Specific targets are: 1

  7. Shear viscosity of the quark matter

    OpenAIRE

    Iwasaki, Masaharu; Ohnishi, Hiromasa; Fukutome, Takahiko

    2007-01-01

    We discuss shear viscosity of the quark matter by using Kubo formula. The shear viscosity is calculated in the framework of the quasi-particle RPA for the Nambu-Jona-Lasinio model. We obtain a formula that the shear viscosity is expressed by the quadratic form of the quark spectral function in the chiral symmetric phase. The magnitude of the shear viscosity is discussed assuming the Breit-Wigner type for the spectral function.

  8. High-Flux Femtosecond X-Ray Emission from Controlled Generation of Annular Electron Beams in a Laser Wakefield Accelerator.

    Science.gov (United States)

    Zhao, T Z; Behm, K; Dong, C F; Davoine, X; Kalmykov, S Y; Petrov, V; Chvykov, V; Cummings, P; Hou, B; Maksimchuk, A; Nees, J A; Yanovsky, V; Thomas, A G R; Krushelnick, K

    2016-08-26

    Annular quasimonoenergetic electron beams with a mean energy in the range 200-400 MeV and charge on the order of several picocoulombs were generated in a laser wakefield accelerator and subsequently accelerated using a plasma afterburner in a two-stage gas cell. Generation of these beams is associated with injection occurring on the density down ramp between the stages. This well-localized injection produces a bunch of electrons performing coherent betatron oscillations in the wakefield, resulting in a significant increase in the x-ray yield. Annular electron distributions are detected in 40% of shots under optimal conditions. Simultaneous control of the pulse duration and frequency chirp enables optimization of both the energy and the energy spread of the annular beam and boosts the radiant energy per unit charge by almost an order of magnitude. These well-defined annular distributions of electrons are a promising source of high-brightness laser plasma-based x rays.

  9. Engineering the group velocities of the guiding modes in two-dimensional annular coupled-cavity waveguides

    Science.gov (United States)

    Feng, Shuai; Chen, Xiao; Yang, Di; Yang, Yuping; Wang, Yiquan

    2011-01-01

    The propagating characteristics of the electromagnetic waves through annular coupled-resonator optical waveguides (CROWs) based on two-dimensional square-lattice photonic crystals are studied by the finite-difference time-domain method. Comparing with the traditional line-typed CROWs, the annular CROW studied in this paper have more minibands within the bandgap. With the increasing of the distance between two adjacent annular cavities, the values of the corresponding group velocities and the field distributions of the guiding modes are numerically calculated. When the annular cavities are interlaced in the direction perpendicular to the waveguide, the group velocities can be further reduced and a maximum value of 0.000 37c can be obtained.

  10. Shear assessment of reinforced concrete slab bridges

    NARCIS (Netherlands)

    Lantsoght, E.O.L.; Van der Veen, C.; Walraven, J.C.; De Boer, A.

    2013-01-01

    The capacity of reinforced concrete solid slab bridges in shear is assessed by comparing the design beam shear resistance to the design value of the applied shear force due to the permanent actions and live loads. Results from experiments on half-scale continuous slab bridges are used to develop a

  11. Longitudinal shear resistance of composite slabs

    NARCIS (Netherlands)

    Schuurman, R.G.; Stark, J.W.B.

    1996-01-01

    Verification methods for longitudinal shear. currently in use, are empirical. This applies for both the m-k method as the Partial Shear Connection method. Parameters and mechanisms determining the behaviour of the shear connection in composite slabs are not directly considered in these methods. A

  12. Developments in Plasticity Approach to Shear

    DEFF Research Database (Denmark)

    Hoang, Cao Linh; Nielsen, Mogens Peter

    1999-01-01

    The paper deals with plastic methods applied to shear design of reinforced concrete beams. Emphasis is put on the recently developed crack sliding model applicable to non-shear reinforced and lightly shear reinforced beams and slabs. The model, which is an upper bound plasticity approach, takes...

  13. Ballistic thermal conductance limited by phonon roughness scattering : A comparison of power-law and Gaussian roughness

    NARCIS (Netherlands)

    Palasantzas, G

    2004-01-01

    In this work, we have investigated the influence of power-law roughness on the ballistic thermal conductance K-TH for a nanosized beam adiabatically connected between two heat reservoirs. The sideways wall beam roughness is assumed to be power-law type, which is described by the roughness amplitude

  14. Use of an annular chamber for testing thermal preference of westslope cutthroat trout and rainbow trout

    Science.gov (United States)

    McMahon, T.E.; Bear, E.A.; Zale, A.V.

    2008-01-01

    Remaining populations of westslope cutthroat trout (Oncorhynchus clarkii lewisi) in western North America are primarily confined to cold headwaters whereas nonnative rainbow trout (Oncorhynchus mykiss) predominate in warmer, lower elevation stream sections historically occupied by westslope cutthroat trout. We tested whether differing thermal preferences could account for the spatial segregation observed in the field. Thermal preferences of age-1 westslope cutthroat trout and rainbow trout (125 to 150 mm total length) were assessed in the laboratory using a modified annular preference chamber at acclimation temperatures of 10, 12, 14, and 16??C Final preferred temperature of westslope cutthroat trout (14.9??C) was similar to that of rainbow trout (14.8??C) when tested in a thermal gradient of 11-17??C The high degree of overlap in thermal preference indicates the two species have similar thermal niches and a high potential for competition. We suggest several modifications to the annular preference chamber to improve performance in future studies.

  15. Transmission loss characteristics of an annular cavity with arbitrary port locations using Green's function method.

    Science.gov (United States)

    Keskar, Harshad; Venkatesham, B

    2017-09-01

    The prediction of transmission loss characteristics of a short chamber requires the study of both longitudinal as well as transverse modes. This prompts the development of a three-dimensional (3D) transfer matrix, which can address the wave propagation in all three directions. Accordingly, an analytical methodology for transmission loss characteristics of an annular cavity using Green's function method is presented in this paper. The 3D wave equation is used to derive the mode shape functions for the cavity. The average pressure on the inlet and outlet ports is predicted using the Green's function derived from the mode shapes. Three different port location configurations of the annular cavity are considered for establishing the analytical methodology, viz., face-inlet-face-outlet (FIFO), side-inlet-side-outlet (SISO), and face-inlet-side-outlet (FISO). Numerical model results are used to corroborate the analytical results. The effects of geometrical parameters on the transmission loss are studied.

  16. Resolution enhancement of pump-probe microscopy with an inverse-annular spatial filter

    Science.gov (United States)

    Kobayashi, T.; Kawasumi, K.; Miyazaki, J.; Nakata, K.

    2016-12-01

    We have introduced a pupil filter, an inverse-annular pupil filter in a pump-probe photothermal microscope, which provides resolution enhancement in three dimensions. The resolution is probed to be improved in lateral and axial resolution by imaging experiment using 20 nm gold nanoparticles. The improvement in X (perpendicular to the common pump and probe polarization direction), Y (parallel to the polarization direction), and Z (axial direction) are by 15±6, 8±8, and 21±2 % from the resolution without a pupil filter. The resolution enhancement is even better than the calculation using vector field, which predicts the corresponding enhancement of 11, 8, and 6 %. The discussion is made to explain the unexpected results. We also demonstrate the photothermal imaging of thick biological samples (cells from rabbit intestine and kidney) stained with hematoxylin and eosin dye with the inverse-annular filter.

  17. Experiments on annular liquid jet instability and on the formation of liquid shells

    Science.gov (United States)

    Kendall, J. M.

    1986-01-01

    An annular jet flow of liquid surrounding a flow of gas at its core is extremely unstable. Experiments are described in which such a flow is generated by an annular nozzle operated at fairly specific conditions. It is shown that periodic, axisymmetric oscillations arise spontaneously within the cylindrical sheet emerging from the nozzle and grow with such rapidity along the axial dimension that a sealing-off and encapsulation of the core gas occurs within a few jet diameters. This is closely followed by a pinchoff of the liquid between adjacent bubbles. The liquid shells set free thereby assume spherically symmetric form under capillary forces, and each contains a precisely uniform measure of gas and of liquid on account of the extremely high frequency-stability of the process. Description is given of the fluid dynamic processes by which the shells are formed, and mention is made of exploiting the instability for the production of rigid shells for technological applications.

  18. Heat Transfer and Pressure Drop in Concentric Annular Flows of Binary Inert Gas Mixtures

    Science.gov (United States)

    Reid, R. S.; Martin, J. J.; Yocum, D. J.; Stewart, E. T.

    2007-01-01

    Studies of heat transfer and pressure drop of binary inert gas mixtures flowing through smooth concentric circular annuli, tubes with fully developed velocity profiles, and constant heating rate are described. There is a general lack of agreement among the constant property heat transfer correlations for such mixtures. No inert gas mixture data exist for annular channels. The intent of this study was to develop highly accurate and benchmarked pressure drop and heat transfer correlations that can be used to size heat exchangers and cores for direct gas Brayton nuclear power plants. The inside surface of the annular channel is heated while the outer surface of the channel is insulated. Annulus ratios range 0.5 spacer ribs, or other surfaces.

  19. Thermal performance of functionally graded parabolic annular fins having constant weight

    Energy Technology Data Exchange (ETDEWEB)

    Gaba, Vivek Kumar; Tiwari, Anil Kumar; Bhowmick, Shubhankar [National Institute of Technology Raipur, Raipur (India)

    2014-10-15

    The proposed work reports the performance of parabolic annular fins of constant weight made of functionally graded materials. The work involves computation of temperature gradient, efficiency and effectiveness of such fins and compares the performances for different functionally graded parabolic fin profiles obtained by varying grading parameters and profile parameters respectively keeping the weight of the fins constant. The functional grading of thermal conductivity is based on a power function of radial co-ordinate which consists of parameters, namely grading parameters, varying which different grading combinations are studied. A general second order ordinary differential equation has been derived for all the profiles and material grading. The efficiency and effectiveness of the annular fins of different profile and grading combinations have been calculated and plotted and the results reveal the dependence of fin performance on profile and grading parameter.

  20. Fully developed MHD natural convection flow in a vertical annular microchannel: An exact solution

    Directory of Open Access Journals (Sweden)

    Basant K. Jha

    2015-07-01

    Full Text Available An exact solution of steady fully developed natural convection flow of viscous, incompressible, electrically conducting fluid in a vertical annular micro-channel with the effect of transverse magnetic field in the presence of velocity slip and temperature jump at the annular micro-channel surfaces is obtained. Exact solution is expressed in terms of modified Bessel function of the first and second kind. The solution obtained is graphically represented and the effects of radius ratio (η, Hartmann number (M, rarefaction parameter (βvKn, and fluid–wall interaction parameter (F on the flow are investigated. During the course of numerical computations, it is found that an increase in Hartmann number leads to a decrease in the fluid velocity, volume flow rate and skin friction. Furthermore, it is found that an increase in curvature radius ratio leads to an increase in the volume flow rate.

  1. Heat Transfer Characteristics of the Supercritical CO{sub 2} Flowing in a Vertical Annular Channel

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Tae Ho; Bae, Yoon Yeong; Kim, Hwan Yeol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-05-15

    Heat transfer test facility, SPHINX(Supercritical Pressure Heat transfer Investigation for NeXt generation), has been operated at KAERI for an investigation of the thermal-hydraulic characteristics of supercritical CO{sub 2} at several test sections with a different geometry. The loop uses CO{sub 2} because it has much lower critical pressure and temperature than those of water. Experimental study of heat transfer to supercritical CO{sub 2} in a vertical annular channel with and hydraulic diameter of 4.5 mm has been performed. CO{sub 2} flows downward through the annular channel simulating the downward-flowing coolant in a multi-pass reactor or water rod moderator in a single pass reactor. The heat transfer characteristics in a downward flow were analyzed and compared with the upward flow test results performed previously with the same test section at KAERI

  2. Amyloid-β Annular Protofibrils Evade Fibrillar Fate in Alzheimer Disease Brain*♦

    Science.gov (United States)

    Lasagna-Reeves, Cristian A.; Glabe, Charles G.; Kayed, Rakez

    2011-01-01

    Annular protofibrils (APFs) represent a new and distinct class of amyloid structures formed by disease-associated proteins. In vitro, these pore-like structures have been implicated in membrane permeabilization and ion homeostasis via pore formation. Still, evidence for their formation and relevance in vivo is lacking. Herein, we report that APFs are in a distinct pathway from fibril formation in vitro and in vivo. In human Alzheimer disease brain samples, amyloid-β APFs were associated with diffuse plaques, but not compact plaques; moreover, we show the formation of intracellular APFs. Our results together with previous studies suggest that the prevention of amyloid-β annular protofibril formation could be a relevant target for the prevention of amyloid-β toxicity in Alzheimer disease. PMID:21507938

  3. Amyloid-β annular protofibrils evade fibrillar fate in Alzheimer disease brain.

    Science.gov (United States)

    Lasagna-Reeves, Cristian A; Glabe, Charles G; Kayed, Rakez

    2011-06-24

    Annular protofibrils (APFs) represent a new and distinct class of amyloid structures formed by disease-associated proteins. In vitro, these pore-like structures have been implicated in membrane permeabilization and ion homeostasis via pore formation. Still, evidence for their formation and relevance in vivo is lacking. Herein, we report that APFs are in a distinct pathway from fibril formation in vitro and in vivo. In human Alzheimer disease brain samples, amyloid-β APFs were associated with diffuse plaques, but not compact plaques; moreover, we show the formation of intracellular APFs. Our results together with previous studies suggest that the prevention of amyloid-β annular protofibril formation could be a relevant target for the prevention of amyloid-β toxicity in Alzheimer disease.

  4. Effects study on the thermal stresses in a LEU metal foil annular target.

    Science.gov (United States)

    Govindarajan, Srisharan G; Solbrekken, Gary L

    2015-09-01

    The effects of fission gas pressure, uranium swelling and thermal contact conductance on the thermal-mechanical behavior of an annular target containing a low-enriched uranium foil (LEU) encapsulated in a nickel foil have been presented in this paper. The draw-plug assembly method is simulated to obtain the residual stresses, which are applied to the irradiation model as initial inputs, and the integrated assembly-irradiation process is simulated as an axisymmetric problem using the commercial finite element code Abaqus FEA. Parametric studies were performed on the LEU heat generation rate and the results indicate satisfactory irradiation performance of the annular target. The temperature and stress margins have been provided along with a discussion of the results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. [Deletion 11q23 --> qter (Jacobsen Syndrome) associated with duodenal atresia and annular pancreas].

    Science.gov (United States)

    Fernández González, N; Prieto Espuñes, S; Ibáñez Fernández, A; Fernández Colomer, B; López Sastre, J; Fernández Toral, J

    2002-09-01

    Jacobsen syndrome is a rare chromosomal disorder due to terminal 11q deletion. Prominent features are growth and psychomotor retardation, trigonocephaly and a characteristic facial dysmorphism, but many different abnormalities have been reported. We present the case of a preterm male. Prenatal ultrasonography was suspicious for duodenal atresia. At birth, the boy presented the craniofacial features typical of Jacobsen syndrome, together with diffusely spread petechiae and talipes equinovarus. Hemogram revealed pancytopenia. Ultrasound examination showed left renal agenesis and confirmed the duodenal atresia. Cerebral computed tomography scan, electroencephalogram and cardiac studies showed no abnormalities. Annular pancreas was found during surgery to correct the duodenal atresia. The karyotype was 46,XY,del(11)(q23.2 --> qter), which confirmed Jacobsen syndrome.A wide spectrum of clinical features is described in Jacobsen syndrome, with phenotype-karyotype correlation. This is the first report of duodenal atresia and annular pancreas.

  6. The propagation of hypergeometric beams through an annular apertured paraxial ABCD optical system

    Science.gov (United States)

    Tang, Bin; Jiang, Chun; Zhu, Haibin; Zhou, Xin; Wang, Shuai

    2014-12-01

    By means of expanding the hard aperture function into a finite sum of complex Gaussian functions and based on the generalized Huygens-Fresnel diffraction integral, a novel approximate analytical expression of hypergeometric (HyG) beams passing through a paraxial ABCD optical system with an annular aperture is derived. The results could be reduced to the case of a circular aperture or a circular black screen. Some numerical simulations are also performed and illustrated for the propagation characteristics and focusing properties of a HyG beam through a paraxial ABCD optical system with an annular aperture. The results obtained from the approximate analytical formula provide more efficiency than the usual way of using diffraction integral formula directly.

  7. Gas turbine structural mounting arrangement between combustion gas duct annular chamber and turbine vane carrier

    Science.gov (United States)

    Wiebe, David J.; Charron, Richard C.; Morrison, Jay A.

    2016-10-18

    A gas turbine engine ducting arrangement (10), including: an annular chamber (14) configured to receive a plurality of discrete flows of combustion gases originating in respective can combustors and to deliver the discrete flows to a turbine inlet annulus, wherein the annular chamber includes an inner diameter (52) and an outer diameter (60); an outer diameter mounting arrangement (34) configured to permit relative radial movement and to prevent relative axial and circumferential movement between the outer diameter and a turbine vane carrier (20); and an inner diameter mounting arrangement (36) including a bracket (64) secured to the turbine vane carrier, wherein the bracket is configured to permit the inner diameter to move radially with the outer diameter and prevent axial deflection of the inner diameter with respect to the outer diameter.

  8. A New Approach to Designing the S-Shaped Annular Duct for Industrial Centrifugal Compressor

    Directory of Open Access Journals (Sweden)

    Ivan Yurko

    2014-01-01

    Full Text Available The authors propose an analytical method for designing the inlet annular duct for an industrial centrifugal compressor using high-order Bezier curves. Using the design of experiments (DOE theory, the three-level full factorial design was developed for determination of influence of the dimensionless geometric parameters on the output criteria. Numerical research was carried out for determination of pressure loss coefficients and velocity swirl angles using the software system ANSYS CFX. Optimal values of the slope for a wide range of geometric parameters, allowing minimizing losses in the duct, have been found. The study has used modern computational fluid dynamics techniques to develop a generalized technique for future development of efficient variable inlet guide vane systems. Recommendations for design of the s-shaped annular duct for industrial centrifugal compressor have been given.

  9. High quantum efficiency annular backside silicon photodiodes for reflectance pulse oximetry in wearable wireless body sensors

    DEFF Research Database (Denmark)

    Duun, Sune Bro; Haahr, Rasmus Grønbek; Hansen, Ole

    2010-01-01

    The development of annular photodiodes for use in a reflectance pulse oximetry sensor is presented. Wearable and wireless body sensor systems for long-term monitoring require sensors that minimize power consumption. We have fabricated large area 2D ring-shaped silicon photodiodes optimized....../2) cm(-1) are achieved. The photodiodes are incorporated into a wireless pulse oximetry sensor system embedded in an adhesive patch presented elsewhere as 'The Electronic Patch'. The annular photodiodes are fabricated using two masked diffusions of first boron and subsequently phosphor. The surface...... is passivated with a layer of silicon nitride also serving as an optical filter. As the final process, after metallization, a hole in the center of the photodiode is etched using deep reactive ion etch....

  10. Annular Lichenoid Dermatitis of Youth: A Report of 2 Cases and a Review of the Literature.

    Science.gov (United States)

    Vázquez-Osorio, I; González-Sabín, M; Gonzalvo-Rodríguez, P; Rodríguez-Díaz, E

    2016-01-01

    Annular lichenoid dermatitis of youth is a lichenoid dermatosis of unknown etiology. It mostly affects children and adolescents and has well-defined clinical and histological characteristics that permit a diagnosis. We present 2 new cases of annular lichenoid dermatitis of youth with classical clinical features in 2 girls, aged 2 and 4 years. The histologic findings, however, differed from those reported in the literature in that the lichenoid inflammatory infiltrate was located primarily at the top of the dermal papillae and not at the tips of the rete ridges. In both cases, the lesions regressed spontaneously without treatment. Copyright © 2016 AEDV. Published by Elsevier España, S.L.U. All rights reserved.

  11. Control of the flow in the annular region of a shrouded cylinder with splitter plate

    Directory of Open Access Journals (Sweden)

    Ozkan Gokturk Memduh

    2017-01-01

    Full Text Available In the present study, the flow control with a splitter plate was studied considering the annular region of a shrouded cylinder. The effect of splitter plate angle, α which was defined according to the cylinder centreline is investigated experimentally in deep water using Particle image Velocimetry (PIV technique and flow visualization by dye injection method. The range of splitter plate angle was selected within 60°≤ α ≤180° with an increment of 30°. The porosity of the shroud which is a perforated cylinder was selected as β=0.7 in order to have larger fluid entrainment through the cylinder. The results were compared with the no-plate case and showed that the splitter plate located in the annular region of shrouded cylinders is effective on reducing the turbulence levels just behind the cylinder base, as well as the near wake of the perforated shroud.

  12. Coherent flow structures in a depth-limited flow over a gravel surface: The influence of surface roughness

    Science.gov (United States)

    Hardy, Richard J.; Best, James L.; Lane, Stuart N.; Carbonneau, Patrice E.

    2010-09-01

    Turbulent flows moving over a gravel bed develop large-scale, macroturbulent flow structures that are initiated at anchor clasts in the bed and grow and dissipate as they move upward through the flow depth. This paper extends previous research in which we investigated the influence of the Reynolds number on coherent flow structures generated over a gravel bed by assessing the importance of effective bed roughness. Here, we report on flume experiments in which flows over beds of decreasing surface roughness have been quantified through the application of digital particle imaging velocimetry, which allows study of the downstream and vertical components of velocity over the entire flow field. These results indicate that as the effective roughness increases (1) the visual distinctiveness of the coherent flow structures becomes more defined throughout the flow depth, (2) the upstream angle of slope of the coherent flow structure increases, and (3) the reduction in streamwise flow velocity and turbulence intensity toward the upstream side of the structure becomes greater. Applying standard scaling laws, these structures appear shear-generated and form through a combination of both wake flapping and the reattachment of localized shear layers associated with flow separation around individual topographic protrusions. As the effective protrusion decreases, the scale of these coherent flow structures also decreases.

  13. Modifications to Marshall's Annular Seal Test (MAST) Rig and Facility for Improved Rotordynamic Coefficient Testing of Annular Seals and Fluid Film Bearings

    Science.gov (United States)

    Darden, J. M.; Earhart, E. M.

    2011-01-01

    The limits of rotordynamic stability continue to be pushed by the high power densities and rotational speeds of modern rocket engine turbomachinery. Destabilizing forces increase dramatically with rotor speed. Rotordynamic stability is lost when these destabilizing forces overwhelm the stabilizing forces. The vibration from the unstable rotor grows until it is limited by some nonlinearity. For example, a rolling element bearing with a stiffness characteristic that increases with deflection may limit the vibration amplitude. The loads and deflections resulting from this limit cycle vibration (LCV) can lead to bearing and seal damage which promotes ever increasing levels of subsynchronous vibration. Engineers combat LCV by introducing rotordynamic elements that generate increased stabilizing forces and reduced destabilizing forces. For example, replacing a labyrinth seal with a damping seal results in substantial increases in the damping and stiffness rotordynamic coefficients. Adding a swirl brake to the damping seal greatly reduces the destabilizing cross-coupled forces generated by the damping seal for even further increases in the stabilizing capacity. Marshall?s Annular Seal Test (MAST) rig is designed to experimentally measure the stabilizing capacity of new annular seal designs. The rig has been moved to a new facility and outfitted with a new slave bearing to allow increased test durations and to enable the testing of fluid film bearings. The purpose of this paper is to describe the new facility and the new bearing arrangement. Several novel seal and bearing designs will also be discussed.

  14. First high-power model of the annular-ring coupled structure for use in the Japan Proton Accelerator Research Complex linac

    Directory of Open Access Journals (Sweden)

    Hiroyuki Ao

    2012-01-01

    Full Text Available A prototype cavity for the annular-ring coupled structure (ACS for use in the Japan Proton Accelerator Research Complex (J-PARC linac has been developed to confirm the feasibility of achieving the required performance. This prototype cavity is a buncher module, which includes ten accelerating cells in total. The ACS cavity is formed by the silver brazing of ACS half-cell pieces stacked in a vacuum furnace. The accelerating cell of the ACS is surrounded by a coupling cell. We, therefore, tuned the frequencies of the accelerating and coupling cells by an ultraprecision lathe before brazing, taking into account the frequency shift due to brazing. The prototype buncher module was successfully conditioned up to 600 kW, which corresponds to an accelerating field that is higher than the designed field of 4.1  MV/m by 30%. We describe the frequency-tuning results for the prototype buncher module and its high-power conditioning.

  15. Observation of silicone tube double-passage annular lacrimal intubation and epidural catheter for repairing the traumatic lacrimal rupture

    OpenAIRE

    Jiang Zhu; Zhen-Ping Huang

    2016-01-01

    AIM:To evaluate the efficacy and characteristics of silicone tube double-passage annular lacrimal intubation and epidural catheter for repairing the traumatic lacrimal rupture. METHODS:Retrospective case study. Sixty-two cases(62 eyes)with traumatic lacrimal rupture were involved in the study from January 2009 to December 2013. Thirty-two cases(32 eyes)were treated with silicone tube double-passage annular lacrimal intubation, 30 cases(30 eyes)with epidural catheter. All cases were underwent ...

  16. Punching shear capacity of reinforced concrete slabs with headed shear studs

    DEFF Research Database (Denmark)

    Hoang, Linh Cao; Pop, Anamaria

    2015-01-01

    Punching shear in slabs is analogous to shear in beams. Despite this similarity, current design codes provide distinctly different methods for the design of shear reinforcement in the two situations. For example, the Eurocode method for beam shear design is founded on the theory of rigid plasticity....... To design shear reinforcement in slabs, on the other hand, the engineer must settle for an empirical equation. The aim of the study reported is to demonstrate that it is possible in a simple manner to design shear reinforcement in slabs based on the same rigid-plasticity foundation as for beam shear design...

  17. Radial midframe baffle for can-annular combustor arrangement having tangentially oriented combustor cans

    Science.gov (United States)

    Rodriguez, Jose L.

    2015-09-15

    A can-annular gas turbine engine combustion arrangement (10), including: a combustor can (12) comprising a combustor inlet (38) and a combustor outlet circumferentially and axially offset from the combustor inlet; an outer casing (24) defining a plenum (22) in which the combustor can is disposed; and baffles (70) configured to divide the plenum into radial sectors (72) and configured to inhibit circumferential motion of compressed air (16) within the plenum.

  18. Operational performance of the three bean salad control algorithm on the ACRR (Annular Core Research Reactor)

    Energy Technology Data Exchange (ETDEWEB)

    Ball, R.M.; Madaras, J.J. (B and W Nuclear Technologies, Lynchburg, VA (USA). Space and Defense Systems); Trowbridge, F.R. Jr.; Talley, D.G.; Parma, E.J. Jr. (Sandia National Labs., Albuquerque, NM (USA))

    1991-01-01

    Experimental tests on the Annular Core Research Reactor have confirmed that the Three-Bean-Salad'' control algorithm based on the Pontryagin maximum principle can change the power of a nuclear reactor many decades with a very fast startup rate and minimal overshoot. The paper describes the results of simulations and operations up to 25 MW and 87 decades per minute. 3 refs., 4 figs., 1 tab.

  19. Direct and ozone-mediated forcing of the Southern Annular Mode by greenhouse gases

    OpenAIRE

    Morgenstern, Olaf; Zeng, Guang; Dean, Sam M.; Joshi, Manoj; Abraham, N. Luke; Osprey, Annette

    2014-01-01

    We assess the roles of long-lived greenhouse gases and ozone depletion in driving meridional surface pressure gradients in the southern extratropics; these gradients are a defining feature of the Southern Annular Mode. Stratospheric ozone depletion is thought to have caused a strengthening of this mode during summer, with increasing long-lived greenhouse gases playing a secondary role. Using a coupled atmosphere-ocean chemistry-climate model, we show that there is cancelation between the dire...

  20. Seasonal variation of moisture transport in polar regions and the relation with annular modes

    OpenAIRE

    Oshima, Kazuhiro; Yamazaki, Koji

    2004-01-01

    Climatological seasonal variations of moisture transport and the interannual variations associated with the annular modes in the Arctic and Antarctic regions are investigated using 15-year ECMWF reanalysis data. Over the Arctic, there are strong moisture inflows from the Atlantic and Pacific in all seasons. Over the Antarctic, a strong moisture inflow exists around the Antarctic Peninsula in all seasons and another strong inflow exists over the Bellingshausen Sea and the Amundsen Sea in austr...

  1. Experimental Study on Pressure Loss of Horizontal Core-Annular Flow

    Science.gov (United States)

    Asiegubu, Chukwuemeka Peter; Asakura, Kuniomi

    In this study, pressure losses associated with a core-annular flow (CAF) through three horizontal pipes of 25 mm, 52.7 mm and 80.1 mm in internal diameter are measured. The working fluids for the core-annular flow are two immiscible fluids, highly viscous oil and water. Oils with viscosities of 2.82 Pa·s at 20°C and 8.92 Pa·s at 20°C are used in the experiment. The oil-water flow rate ratios (ratio of oil flow rate to water flow rate) are set at 2.6, 3.0, 3.4, 4.0 and 4.6 for the pipe of 25 mm in diameter and at 4.0 for the pipes of 52.7 mm and 80.1 mm in diameter. Based on the results of the experiment, a simple model for the pressure loss of a core-annular flow is derived. This model is used to estimate pressure losses of core-annular flows at various flow rate ratios and pipe diameters. To validate the model, the pressure loss data from the experiment are compared with those of the model. The comparison shows that this model is useful for predicting pressure loss of a CAF when oil does not wet the pipe wall extensively. In addition, it is observed in the experiment that pressure loss of CAF with the two viscous liquids is slightly higher than that of single-phase water. This indicates that pressure loss of a CAF is largely independent of oil viscosity.

  2. Core-annular miscible two-fluid flow in a slippery pipe: A stability analysis

    Science.gov (United States)

    Chattopadhyay, Geetanjali; Usha, Ranganathan; Sahu, Kirti Chandra

    2017-09-01

    This study is motivated by the preliminary direct numerical simulations in double-diffusive (DD) core-annular flows with slip at the wall which displayed elliptical shaped instability patterns as in a rigid pipe case; however, slip at the pipe wall delays the onset of instability for a range of parameters and increases the phase speed. This increased our curiosity to have a thorough understanding of the linear stability characteristics of the miscible DD two-fluid flow in a pipe with slip at the pipe wall. The present study, therefore, addresses the linear stability of viscosity-stratified core-annular Poiseuille flow of miscible fluids with matched density in a slippery pipe in the presence of two scalars diffusing at different rates. The physical mechanisms responsible for the occurrence of instabilities in the DD system are explained through an energy budget analysis. The differences and similarities between core-annular flow in a slippery pipe and in a plane channel with velocity slip at the walls are explored. The stability characteristics are significantly affected by the presence of slip. The diffusivity effect is non-monotonic in a DD system. A striking feature of instability is that only a band of wavenumbers is destabilized in the presence of moderate to large inertial effects. Both the longwave and shortwave are stabilized at small Reynolds numbers. Slip exhibits a dual role of stabilizing or destabilizing the flow. The preliminary direct numerical simulations confirm the predictions of the linear stability analysis. The present study reveals that it may be possible to control the instabilities in core-annular pressure driven pipe flows by imposing a velocity slip at the walls.

  3. Amyloid-β Annular Protofibrils Evade Fibrillar Fate in Alzheimer Disease Brain*♦

    OpenAIRE

    Lasagna-Reeves, Cristian A; Charles G Glabe; Kayed, Rakez

    2011-01-01

    Annular protofibrils (APFs) represent a new and distinct class of amyloid structures formed by disease-associated proteins. In vitro, these pore-like structures have been implicated in membrane permeabilization and ion homeostasis via pore formation. Still, evidence for their formation and relevance in vivo is lacking. Herein, we report that APFs are in a distinct pathway from fibril formation in vitro and in vivo. In human Alzheimer disease brain samples, amyloid-β APFs were associated with ...

  4. Microwave generation enhancement of X-band CRBWO by use of coaxial dual annular cathodes

    OpenAIRE

    Yan Teng; Jun Sun; Changhua Chen; Hao Shao

    2013-01-01

    This paper presents an approach that greatly enhances both the output power and the conversion efficiency of the coaxial relativistic backward wave oscillator (CRBWO) by using coaxial dual annular cathodes, which increases the diode current rather than the diode voltage. The reasons for the maladjustment of CRBWO under a high diode voltage are analyzed theoretically. It is found that by optimization of the diode structure, the shielding effect of the space charge of the outer beams on the inn...

  5. Efficiency of applying low-intensity laser radiation in treating patients with granuloma annulare

    Science.gov (United States)

    Kochetkov, M. A.; Volnukhin, Vladimir A.; Kozlov, Valentine I.

    2001-04-01

    This article considers the application of low-intensity laser therapy in treating patients with granuloma annulare. The treatment was carried out by using two different laser therapeutic techniques, namely, the local laser irradiation of pathological foci and the laser transcutaneous irradiation of blood. It was found that both techniques produced a unidirectional effect, brought about a pronounced improvement of the clinical picture of the disease, and normalized microcirculation and microvascular reactivity of the affected skin.

  6. An investigation of force, surface roughness and chip in surface grinding of SKD 11 tool steel using minimum quantity lubrication-MQL technique

    Science.gov (United States)

    Soepangkat, Bobby O. P.; Agustin, H. C. Kis; Subiyanto, H.

    2017-06-01

    This research aimed to analyze the viability of the minimum quantity of lubricant (MQL) technique towards normal force, tangential force, surface roughness and chip formation in surface grinding of SKD 11 tool steel. The three surface grinding parameters were varied including the type of cooling method (MQL and dry), table speed, and depth of cut. Based on statistical analysis, depth of cut is the most influential factor which affects the four responses in both dry and MQL grinding. MQL could reduce normal force and tangential force considerably, but produce higher surface roughness. In MQL grinding, the chips removal took place mostly by shearing and fracturing.

  7. A Comparative Study of Some Soft Rough Sets

    Directory of Open Access Journals (Sweden)

    Yaya Liu

    2017-10-01

    Full Text Available Through the combination of different types of sets such as fuzzy sets, soft sets and rough sets, abundant hybrid models have been presented in order to take advantage of each other and handle uncertainties. A comparative study of relationships and interconnections of some existing hybrid models has been carried out. Some foundational properties of modified soft rough sets (MSR sets are analyzed. It is pointed out that MSR approximation operators are some kinds of Pawlak approximation operators, whereas approximation operators of Z-soft rough fuzzy sets are equivalent to approximation operators of rough fuzzy sets. The relationships among F-soft rough fuzzy sets, M-soft rough fuzzy sets and Z-soft rough fuzzy sets are surveyed. A new model called soft rough soft sets has been provided as the generalization of F-soft rough sets, and its application in group decision-making has been studied. Various soft rough sets models show great potential as a tool to solve decision-making problems, and a depth study of the connections among these models contributes to the flexible application of soft rough sets based decision-making approaches.

  8. Internal surface roughness of plastic pipes for irrigation

    Directory of Open Access Journals (Sweden)

    Hermes S. da Rocha

    Full Text Available ABSTRACT Assuming that a roughness meter can be successfully employed to measure the roughness on the internal surface of irrigation pipes, this research had the purpose of defining parameters and procedures required to represent the internal surface roughness of plastic pipes used in irrigation. In 2013, the roughness parameter Ra, traditional for the representation of surface irregularities in most situations, and the parameters Rc, Rq, and Ry were estimated based on 350 samples of polyvinyl chloride (PVC and low-density polyethylene (LDPE pipes. Pressure losses were determined from experiments carried out in laboratory. Estimations of pressure loss varied significantly according to the roughness parameters (Ra, Rc, Rq, and Ry and the corresponding pipe diameter. Therefore, specific values of roughness for each pipe diameter improves accuracy in pressure losses estimation. The average values of internal surface roughness were 3.334 and 8.116 μm for PVC and LDPE pipes, respectively.

  9. Statistical Model of Extreme Shear

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose; Larsen, Gunner Chr.

    2005-01-01

    (PDF) of turbulence driven short-term extreme wind shear events, conditioned on the mean wind speed, for an arbitrary recurrence period. The model is based on an asymptotic expansion, and only a few and easily accessible parameters are needed as input. The model of the extreme PDF is supplemented...... by a model that, on a statistically consistent basis, describes the most likely spatial shape of an extreme wind shear event. Predictions from the model have been compared with results from an extreme value data analysis, based on a large number of full-scale measurements recorded with a high sampling rate......In order to continue cost-optimisation of modern large wind turbines, it is important to continuously increase the knowledge of wind field parameters relevant to design loads. This paper presents a general statistical model that offers site-specific prediction of the probability density function...

  10. Design of wind shear filters

    Science.gov (United States)

    Joerck, H.

    1984-01-01

    A number of aircraft accidents are caused by the effects of wind shear. In connection with efforts to eliminate or reduce hazards leading to such accidents, the possibility was considered to improve aircraft control systems. However, the effective implementation of the considered approaches will only be possible if suitable filters can be designed for a separation of gusts, which involve higher frequencies from low-frequency wind shear components. Filters of appropriate design should be suited for an employment in connection with all flight conditions. Feasible approaches for obtaining such filters are discussed. A survey is provided regarding the order of magnitude of the improvements which can be achieved, taking into account the performance characteristics of the A300 controller.

  11. Echo signal from rough planar interfaces influence of roughness, angle, range and transducer type

    DEFF Research Database (Denmark)

    Wilhjelm, Jens E.; Pedersen, P.C.; Jacobsen, S.M.

    1998-01-01

    The received electrical signal from a pulse-echo system insonifying a planar acoustical interface was measured for varying degrees of rms roughness (0-0.16 mm), angle of incidence (typically +/-7°) and range to the transducer. A planar and a focused 5 MHz transducer was used. When insonifying a s...

  12. Influence of surface roughness on nonlinear flow behaviors in 3D self-affine rough fractures: Lattice Boltzmann simulations

    Science.gov (United States)

    Wang, Min; Chen, Yi-Feng; Ma, Guo-Wei; Zhou, Jia-Qing; Zhou, Chuang-Bing

    2016-10-01

    This study investigates the impacts of surface roughness on the nonlinear fluid flow through three-dimensional (3D) self-affine rock fractures, whose original surface roughness is decomposed into primary roughness (i.e. the large-scale waviness of the fracture morphology) and secondary roughness (i.e. the small-scale unevenness) with a wavelet analysis technique. A 3D Lattice Boltzmann method (LBM) is adopted to predict the flow physics in rock fractures numerically created with and without consideration of the secondary roughness, respectively. The simulation results show that the primary roughness mostly controls the pressure distribution and fracture flow paths at a large scale, whereas the secondary roughness determines the nonlinear properties of the fluid flow at a local scale. As the pressure gradient increases, the secondary roughness enhances the local complexity of velocity distribution by generating and expanding the eddy flow and back flow regions in the vicinity of asperities. It was found that the Forchheimer's law characterizes well the nonlinear flow behavior in fractures of varying roughness. The inertial effects induced by the primary roughness differ only marginally in fractures with the roughness exponent varying from 0.5 to 0.8, and it is the secondary roughness that significantly enhances the nonlinear flow and leads to earlier onset of nonlinearity. Further examined were the effects of surface roughness on the transmissivity, hydraulic aperture and the tortuosity of flow paths, demonstrating again the dominant role of the secondary roughness, especially for the apparent transmissivity and the equivalent hydraulic aperture at high pressure gradient or high Reynolds number. The results may enhance our understanding of the role of surface roughness in the nonlinear flow behaviors in natural rock fractures.

  13. Annular electron energy-loss spectroscopy in the scanning transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Ruben, Gary [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Bosman, Michel [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); D' Alfonso, Adrian J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Okunishi, Eiji; Kondo, Yukihito [JEOL Ltd., 1-2, Musashino 3-chome Akishima, Tokyo 196-8558 (Japan); Allen, Leslie J., E-mail: lja@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia)

    2011-11-15

    We study atomic-resolution annular electron energy-loss spectroscopy (AEELS) in scanning transmission electron microscopy (STEM) imaging with experiments and numerical simulations. In this technique the central part of the bright field disk is blocked by a beam stop, forming an annular entry aperture to the spectrometer. The EELS signal thus arises only from electrons scattered inelastically to angles defined by the aperture. It will be shown that this method is more robust than conventional EELS imaging to variations in specimen thickness and can also provide higher spatial resolution. This raises the possibility of lattice resolution imaging of lighter elements or ionization edges previously considered unsuitable for EELS imaging. -- Highlights: Black-Right-Pointing-Pointer We study annular electron energy-loss spectroscopy (AEELS) in STEM. Black-Right-Pointing-Pointer This is more robust to changes in specimen thickness than conventional EELS. Black-Right-Pointing-Pointer AEELS provides higher spatial resolution than conventional EELS. Black-Right-Pointing-Pointer This raises the possibility of lattice resolution imaging of lighter elements.

  14. Modeling of annular two-phase flow using a unified CFD approach

    Energy Technology Data Exchange (ETDEWEB)

    Li, Haipeng, E-mail: haipengl@kth.se; Anglart, Henryk, E-mail: henryk@kth.se

    2016-07-15

    Highlights: • Annular two-phase flow has been modeled using a unified CFD approach. • Liquid film was modeled based on a two-dimensional thin film assumption. • Both Eulerian and Lagrangian methods were employed for the gas core flow modeling. - Abstract: A mechanistic model of annular flow with evaporating liquid film has been developed using computational fluid dynamics (CFD). The model is employing a separate solver with two-dimensional conservation equations to predict propagation of a thin boiling liquid film on solid walls. The liquid film model is coupled to a solver of three-dimensional conservation equations describing the gas core, which is assumed to contain a saturated mixture of vapor and liquid droplets. Both the Eulerian–Eulerian and the Eulerian–Lagrangian approach are used to describe the droplet and vapor motion in the gas core. All the major interaction phenomena between the liquid film and the gas core flow have been accounted for, including the liquid film evaporation as well as the droplet deposition and entrainment. The resultant unified framework for annular flow has been applied to the steam-water flow with conditions typical for a Boiling Water Reactor (BWR). The simulation results for the liquid film flow rate show good agreement with the experimental data, with the potential to predict the dryout occurrence based on criteria of critical film thickness or critical film flow rate.

  15. Asymmetric Vibration of Polar Orthotropic Annular Circular Plates of Quadratically Varying Thickness with Same Boundary Conditions

    Directory of Open Access Journals (Sweden)

    N. Bhardwaj

    2008-01-01

    Full Text Available In the present paper, asymmetric vibration of polar orthotropic annular circular plates of quadratically varying thickness resting on Winkler elastic foundation is studied by using boundary characteristic orthonormal polynomials in Rayleigh-Ritz method. Convergence of the results is tested and comparison is made with results already available in the existing literature. Numerical results for the first ten frequencies for various values of parameters describing width of annular plate, thickness profile, material orthotropy and foundation constant for all three possible combinations of clamped, simply supported and free edge conditions are shown and discussed. It is found that (a higher elastic property in circumferential direction leads to higher stiffness against lateral vibration; (b Lateral vibration characteristics of F-Fplates is more sensitive towards parametric changes in material orthotropy and foundation stiffness than C-C and S-Splates; (c Effect of quadratical thickness variation on fundamental frequency is more significant in cases of C-C and S-S plates than that of F-Fplates. Thickness profile which is convex relative to plate center-line tends to result in higher stiffness of annular plates against lateral vibration than the one which is concave and (d Fundamental mode of vibration of C-C and S-Splates is axisymmetrical while that of F-Fplates is asymmetrical.

  16. Frictional pressure losses for annular flow of drilling mud and mud-gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Langlinais, J.P.; Bourguyne, A.T.; Holden, W.R.

    1985-03-01

    The calculation of single-phase and two-phase flowing pressure gradients in a well annulus is generally based on an extension of empirical correlations developed for Newtonian fluids in circular pipes. Various techniques for extending pipe flow correlations to an annular geometry have been presented in the literature which involve the representation of the annular well geometry with an equivalent circular diameter and the representation of non-Newtonian fluid behavior with an apparent Newtonian viscosity. Unfortunately, little experimental data have been available which would allow a comparison of the relative accuracy of the various proposed techniques. In this study, experimental pressure gradient data have been taken in two 6000-ft wells. Frictional pressure losses for single-phase flow (mud only) in two annuli were compared to values predicted by the Bingham plastic and power law models. These calculations utilized the equivalent diameters defined by the Crittendon criteria, the hydraulic diameter, and the slot approximation. Also, total pressure difference for two-phase flow was measured for one annular geometry. This data was compared to that predicted by the Poettmann and Carpenter, Hagedorn and Brown, Orkiszewski, and Beggs and Brill correlations. Comparison of experimental data with the various prediction techniques was favorable, each having advantage in certain situations. For the data investigated, the Crittendon criteria using a Bingham plastic model gave the best results. The two-phase flow data was best predicted by the Hagedorn and Brown correlation utilizing an equivalent hydraulic diameter.

  17. Automatic Measurements of Mitral Annular Plane Systolic Excursion and Velocities to Detect Left Ventricular Dysfunction.

    Science.gov (United States)

    Grue, Jahn Frederik; Storve, Sigurd; Dalen, Håvard; Salvesen, Øyvind; Mjølstad, Ole Christian; Samstad, Stein O; Torp, Hans; Haugen, Bjørn Olav

    2018-01-01

    The purpose of the study described here was to evaluate an automatic algorithm for detection of left ventricular dysfunction, based on measurements of mitral annular motion indices from color tissue Doppler apical four-chamber recordings. Two hundred twenty-one patients, among whom 49 had systolic and 11 had diastolic dysfunction, were included. Echocardiographic evaluation by cardiologists was the reference. Twenty patients were also examined by medical students. The ability of the indices to detect systolic and diastolic dysfunction were compared in receiver operating characteristic analyses, and the agreement between automatic and reference measurements was evaluated. Mitral annular plane systolic excursion ≤10 mm detected left ventricular dysfunction with 82% specificity, 76% specificity, 56% positive predictive value and 92% negative predictive value. The automatic measurements acquired from expert recordings better agreed better with the reference than those acquired from student recordings. We conclude that automatic measurements of systolic mitral annular motion indices can be helpful in detection of left ventricular dysfunction. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  18. In-Plane Vibration Analysis of Annular Plates with Arbitrary Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Xianjie Shi

    2014-01-01

    Full Text Available In comparison with the out-of-plane vibrations of annular plates, far less attention has been paid to the in-plane vibrations which may also play a vital important role in affecting the sound radiation from and power flows in a built-up structure. In this investigation, a generalized Fourier series method is proposed for the in-plane vibration analysis of annular plates with arbitrary boundary conditions along each of its edges. Regardless of the boundary conditions, the in-plane displacement fields are invariantly expressed as a new form of trigonometric series expansions with a drastically improved convergence as compared with the conventional Fourier series. All the unknown expansion coefficients are treated as the generalized coordinates and determined using the Rayleigh-Ritz technique. Unlike most of the existing studies, the presented method can be readily and universally applied to a wide spectrum of in-plane vibration problems involving different boundary conditions, varying material, and geometric properties with no need of modifying the basic functions or adapting solution procedures. Several numerical examples are presented to demonstrate the effectiveness and reliability of the current solution for predicting the in-plane vibration characteristics of annular plates subjected to different boundary conditions.

  19. Dynamic Response of Rub Caused by a Shedding Annular Component Happening in a Steam Turbine

    Directory of Open Access Journals (Sweden)

    J. M. Chen

    2015-01-01

    Full Text Available Rub caused by a shedding annular component is a severe fault happening in a steam turbine, which could result in a long-term wearing effect on the shaft. The shafting abrasion defects shortened the service life and damaged the unit. To identify the fault in time, the dynamic response of rub caused by a shedding annular component was studied as follows: (I a rotor-bearing model was established based on the structural features of certain steam turbines; node-to-node contact constraint and penalty method were utilized to analyze the impact and friction; (II dynamic response of the rotor-bearing system and the shedding component was simulated with the development of rub after the component was dropping; (III fault features were extracted from the vibration near the bearing position by time-domain and frequency-domain analysis. The results indicate that the shedding annular component would not only rotate pivoting its axis but also revolve around the shaft after a period of time. Under the excitation of the contact force, the peak-peak vibration fluctuates greatly. The frequency spectrum contains two main components, that is, the working rotating frequency and revolving frequency. The same phenomenon was observed from the historical data in the field.

  20. CFD Study of an Annular-Ducted Fan Lift System for VTOL Aircraft

    Directory of Open Access Journals (Sweden)

    Yun Jiang

    2015-09-01

    Full Text Available The present study aimed at assessing a novel annular-ducted fan lift system for VTOL aircraft through computational fluid dynamics (CFD simulations. The power and lift efficiency of the lift fan system in hover mode, the lift and drag in transition mode, the drag and flight speed of the aircraft in cruise mode and the pneumatic coupling of the tip turbine and jet exhaust were studied. The results show that the annular-ducted fan lift system can have higher lift efficiency compared to the rotor of the Apache helicopter; the smooth transition from vertical takeoff to cruise flight needs some extra forward thrust to overcome a low peak of drag; the aircraft with the lift fan system enclosed during cruise flight theoretically may fly faster than helicopters and tiltrotors based on aerodynamic drag prediction, due to the elimination of rotor drag and compressibility effects on the rotor blade tips; and pneumatic coupling of the tip turbine and jet exhaust of a 300 m/s velocity can provide enough moment to spin the lift fan. The CFD results provide insight for future experimental study of the annular-ducted lift fan VTOL aircraft.

  1. In-water gas combustion in linear and annular gas bubbles

    Science.gov (United States)

    Teslenko, V. S.; Drozhzhin, A. P.; Medvedev, R. N.; Batraev, I. S.

    2014-08-01

    A new pulsed-cyclic method of in-water gas combustion was developed with separate feed of fuel gas and oxygen with the focus on development of new technologies for heat generators and submerged propellers. The results of calorimetric and hydrodynamic measurements are presented. In-water combustion of acetylene, hydrogen, and propane was tested with the operation frequency of 2-2.5 Hz and with a linear injector. The combustion dynamics of combustion of stoichiometric mixture with propane (C3H8+5O2) was studied for a bubble near a solid wall; the produced gas bubble continues expansion and oscillations (for the case of linear and annular bubbles). It was demonstrated that gas combustion in annular bubbles produces two same-magnitude pulses of force acting on the wall. The first pulse is produced due to expansion of combustion products, and the second pulse is produced due to axial cumulative processes after bubble collapse. This process shapes an annular vortex which facilitates high-speed convective processes between combustion products and liquid; and this convection produces small-size bubbles.

  2. Monitoring system of depressurization valves of migrated gas in annular space of flexible risers

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, Luiz A.; Santos, Joilson M.; Carvalho, Antonio L.; Loureiro, Patricia [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2005-07-01

    PETROBRAS Research and Development Center - CENPES developed an automatic system for monitoring pressure of annular space due to permeation of gas in flexible risers to inspect continuously integrity of such lines. To help maintaining physical integrity of flexible risers, two PSV's are installed to end fittings on top of riser, so that operation of any valve grants the maximum admissible gas pressure within the riser annular space, as overpressure might cause damages to external polymeric layer of flexible riser. Due to the fact that there is no mechanism allowing operation to verify correct PSV performance and frequency of valve's closings and openings, we felt to be necessary the development and implement an automatic instrumented system, integrated to platform's automation and control infrastructure. The objective of this instrumentation is to monitor and register pressure of annular space in flexible riser, as well as XV's depressurization frequency. Having such information registered and monitored, can infer some riser structural conditions, anticipating repairs and preventive maintenance. In this paper we present developed system details including instruments required, application, operation of associated screens that are used in the ECOS, with events, alarms and industrial automation services required (Application development and system integration). (author)

  3. Development of electron optical system using annular pupils for scanning transmission electron microscope by focused ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Matsutani, Takaomi, E-mail: matutani@ele.kindai.ac.jp [Kinki University, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8502 (Japan); Yasumoto, Tsuchika; Tanaka, Takeo [Osaka Sangyo University, 3-1-1 Nakagaito, Daito, Osaka 574-8530 (Japan); Kawasaki, Tadahiro; Ichihashi, Mikio [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Ikuta, Takashi [Osaka Electro-Communication University, 18-8 Hatsu-cho, Neyagawa, Osaka 572-8530 (Japan)

    2012-02-01

    Annular pupils for electron optics were produced using a focused ion beam (FIB), enabling an increase in the depth of focus and allowing for aberration-free imaging and separation of the amplitude and phase images in a scanning transmission electron microscope (STEM). Simulations demonstrate that an increased focal depth is advantageous for three-dimensional tomography in the STEM. For a 200 kV electron beam, the focal depth is increased to approximately 100 nm by using an annular pupil with inner and outer semi-angles of 29 and 30 mrad, respectively. Annular pupils were designed with various outer diameters of 40-120 {mu}m and the inner diameter was designed at 80% of the outer diameter. A taper angle varying from 1 Degree-Sign to 20 Degree-Sign was applied to the slits of the annular pupils to suppress the influence of high-energy electron scattering. The fabricated annular pupils were inspected by scanning ion beam microscopy and scanning electron microscopy. These annular pupils were loaded into a STEM and no charge-up effects were observed in the scintillator projection images recorded by a CCD camera.

  4. Rough and partially-cemented fracture permeability

    Science.gov (United States)

    Landry, C. J.; Eichhubl, P.; Prodanovic, M.

    2016-12-01

    Numerical studies of mass transport in fractured rock, such as discrete fracture network models, use models to assign estimates of permeability to individual fractures. These fracture permeability models typically employ statistical moments of the fracture aperture distribution to estimate permeability. Although it is known that these fracture permeability models are in error, the quantification of this error is limited. We use a digital rock physics workflow to quantify this error in four fracture samples, a barren artificially-induced fracture in sandstone, a calcite-lined fracture sampled from outcrop, and two quartz-bridged fractures sampled from reservoir core. Each of the fracture samples is imaged using three-dimensional x-ray computed microtomography. The images are then processed, segmented and used in a lattice-Boltzmann-method-based flow simulation. We also vary the kinematic apertures of the barren and calcite-lined fractures through digital dilatation and closure in order to investigate sensitivity to the relative fracture roughness. We define the scalar error, F, between the actual permeability determined from simulation, kLB, and that predicted using the fracture permeability model of Zimmerman and Bodvarsson (1996), kZB, as, F±1=kZB/kLB. Although the pore space shape of the fractures appears quite different, the scalar error as a function of relative roughness is found to be similar for all fracture samples investigated, with a maximum of approximately 2. Considering two-dimensional cross-sections of fractures are more readily available than three-dimensional images we then plot the scalar error as a function of relative roughness and the number of observations measured from two-dimensional images (width of fracture analyzed). In general, the rougher the fracture, the greater the number of observations that are required to define the statistical moment inputs for the fracture permeability model. We use these results to approximate the width of the

  5. Fracture structure near a longitudinal shear macrorupture

    Science.gov (United States)

    Goldstein, R. V.; Osipenko, N. M.

    2012-09-01

    Fracture evolution the near a main longitudinal shear in the presence of normal stresses is studied. Experiments with model materials (gypsum, cheese) showed that a multiscale echelon structure of cracks feathering the main rupture is formed under the shear domination conditions. A system of small cracks in the initial echelon is replaced by an echelon of larger and sparser cracks. Intensive transverse compression along the normal to the shear plane, which imitates the initial stress concentrator, takes the fracture region away from the shear plane. A model of evolution development of the observed echelon structure along the main rupture front under the shear domination conditions is proposed.

  6. Shear viscosity of nuclear matter

    Science.gov (United States)

    Magner, A. G.; Gorenstein, M. I.; Grygoriev, U. V.; Plujko, V. A.

    2016-11-01

    Shear viscosity η is calculated for the nuclear matter described as a system of interacting nucleons with the van der Waals (VDW) equation of state. The Boltzmann-Vlasov kinetic equation is solved in terms of the plane waves of the collective overdamped motion. In the frequent-collision regime, the shear viscosity depends on the particle-number density n through the mean-field parameter a , which describes attractive forces in the VDW equation. In the temperature region T =15 -40 MeV, a ratio of the shear viscosity to the entropy density s is smaller than 1 at the nucleon number density n =(0.5 -1.5 ) n0 , where n0=0.16 fm-3 is the particle density of equilibrium nuclear matter at zero temperature. A minimum of the η /s ratio takes place somewhere in a vicinity of the critical point of the VDW system. Large values of η /s ≫1 are, however, found in both the low-density, n ≪n0 , and high-density, n >2 n0 , regions. This makes the ideal hydrodynamic approach inapplicable for these densities.

  7. Shear stress regulates occludin content and phosphorylation.

    Science.gov (United States)

    DeMaio, L; Chang, Y S; Gardner, T W; Tarbell, J M; Antonetti, D A

    2001-07-01

    Previous studies determined that shear stress imposed on bovine aortic endothelial cell (BAEC) monolayers increased the hydraulic conductivity (L(P)); however, the mechanism by which shear stress increases L(P) remains unknown. This study tested the hypothesis that shear stress regulates paracellular transport by altering the expression and phosphorylation state of the tight junction protein occludin. The effect of shear stress on occludin content was examined by Western blot analysis. Ten dyn/cm(2) significantly reduced occludin content in a time-dependent manner such that after a 3 h exposure to shear, occludin content decreased to 44% of control. Twenty dyn/cm(2) decreased occludin content to 50% of control and increased L(P) by 4.7-fold after 3 h. Occludin expression and L(P) depend on tyrosine kinase activity because erbstatin A (10 microM) attenuated both the shear-induced decrease in occludin content and increase in L(P). Shear stress increased occludin phosphorylation after 5 min, 15 min, and 3 h exposures. The shear-induced increase in occludin phosphorylation was attenuated with dibutyryl (DB) cAMP (1 mM), a reagent previously shown to reverse the shear-induced increase in L(P). We conclude that shear stress rapidly (shear stress increases L(P).

  8. Reproducibility of surface roughness in reaming

    DEFF Research Database (Denmark)

    Müller, Pavel; De Chiffre, Leonardo

    An investigation on the reproducibility of surface roughness in reaming was performed to document the applicability of this approach for testing cutting fluids. Austenitic stainless steel was used as a workpiece material and HSS reamers as cutting tools. Reproducibility of the results was evaluated...... of tool geometry and path. 2D and 3D reference measurements were done to ensure traceability of the measurement. Moreover, surface profiles were examined under the 3D optical microscope. Measuring uncertainty evaluation using statistical methods was applied. Surfaces produced with a low cutting speed were....... High reproducibility of different operators, especially when low cutting speed was applied, was achieved. From the surface profiles, an identification of individual feed marks from the tool is possible, tool replication being most clear from the 3D reference measurements....

  9. Backscatter enhancement in scattering from rough surfaces

    Science.gov (United States)

    Papa, Robert J.; Woodworth, Margaret B.

    1989-06-01

    Stealth technology has advanced to the point where radar target cross sections are so small there is a great need to determine mean clutter cross sections and clutter variability with great accuracy. Established clutter prediction techniques result in forward scatter values that exceed backscatter. There is some new experimental data on light scattering from rough metallic surfaces which shows there is an enhancement of backscattering in the antispecular direction under some conditions. This unusual result has been addressed by several theoretical analyses with varying success at confirmation. In this report an integral form of a physical optics representation is used to simulate the experimental conditions. For a one-dimensional surface height variation this model predicts enhanced backscatter at optical frequencies. Additional calculations for the more significant radar case of microwave frequencies and a dielectric surface again predict an increase in backscatter for large or intermediate surface slope conditions.

  10. Manning's roughness coefficient for Illinois streams

    Science.gov (United States)

    Soong, David T.; Prater, Crystal D.; Halfar, Teresa M.; Wobig, Loren A.

    2012-01-01

    Manning's roughness coefficients for 43 natural and constructed streams in Illinois are reported and displayed on a U.S. Geological Survey Web site. At a majority of the sites, discharge and stage were measured, and corresponding Manning's coefficients—the n-values—were determined at more than one river discharge. The n-values discussed in this report are computed from data representing the stream reach studied and, therefore, are reachwise values. Presentation of the resulting n-values takes a visual-comparison approach similar to the previously published Barnes report (1967), in which photographs of channel conditions, description of the site, and the resulting n-values are organized for each site. The Web site where the data can be accessed and are displayed is at URL http://il.water.usgs.gov/proj/nvalues/.

  11. Quantitative Characterization of Boundary Roughness in Metals

    DEFF Research Database (Denmark)

    Sun, Jun

    The boundary migration during recrystallization is by nature a heterogeneous process and local structural variations form on recrystallization boundaries, as revealed from modern techniques such as synchrotron X-rays and advanced electron microscopy. The local structural variations, in the form...... of protrusions and retrusions, can provide a dragging/driving force due to the local boundary curvature and affect the further migration of recrystallization boundaries through the deformed matrix. In order to develop new understandings and models for boundary migration that take the heterogeneous local...... structural aspects into account, a detailed characterization is essential of partly recrystallized microstructures focusing on the local shapes of the boundaries, in particular on whether protrusions and retrusions are formed or not. Quantification of the “amount” of boundary roughness in the form...

  12. Enhanced thermoelectric performance of rough silicon nanowires

    Science.gov (United States)

    Hochbaum, Allon I.; Chen, Renkun; Delgado, Raul Diaz; Liang, Wenjie; Garnett, Erik C.; Najarian, Mark; Majumdar, Arun; Yang, Peidong

    2008-01-01

    Approximately 90 per cent of the world's power is generated by heat engines that use fossil fuel combustion as a heat source and typically operate at 30-40 per cent efficiency, such that roughly 15terawatts of heat is lost to the environment. Thermoelectric modules could potentially convert part of this low-grade waste heat to electricity. Their efficiency depends on the thermoelectric figure of merit ZT of their material components, which is a function of the Seebeck coefficient, electrical resistivity, thermal conductivity and absolute temperature. Over the past five decades it has been challenging to increase ZT>1, since the parameters of ZT are generally interdependent. While nanostructured thermoelectric materials can increase ZT>1 (refs 2-4), the materials (Bi, Te, Pb, Sb, and Ag) and processes used are not often easy to scale to practically useful dimensions. Here we report the electrochemical synthesis of large-area, wafer-scale arrays of rough Si nanowires that are 20-300nm in diameter. These nanowires have Seebeck coefficient and electrical resistivity values that are the same as doped bulk Si, but those with diameters of about 50nm exhibit 100-fold reduction in thermal conductivity, yielding ZT = 0.6 at room temperature. For such nanowires, the lattice contribution to thermal conductivity approaches the amorphous limit for Si, which cannot be explained by current theories. Although bulk Si is a poor thermoelectric material, by greatly reducing thermal conductivity without much affecting the Seebeck coefficient and electrical resistivity, Si nanowire arrays show promise as high-performance, scalable thermoelectric materials.

  13. Characterization of rough interfaces obtained by boriding

    Energy Technology Data Exchange (ETDEWEB)

    Campos-Silva, I. [Instituto Politecnico Nacional, SEPI-ESIME, U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico)], E-mail: icampos@ipn.mx; Balankin, A.S. [Instituto Politecnico Nacional, SEPI-ESIME, U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico); Sierra, A.H. [Instituto Politecnico Nacional, UPIICSA, Av. Te 950, Col Granjas, Mexico D.F. 08400 (Mexico); Lopez-Perrusquia, N. [Instituto Politecnico Nacional, SEPI-ESIME, U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico); Escobar-Galindo, R. [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, Madrid E-28049 (Spain); Morales-Matamoros, D. [Instituto Mexicano del Petroleo, Eje Lazaro Cardenas Norte, Mexico D.F. 07738 (Mexico)

    2008-12-30

    This study evaluates the morphology of borided interfaces by means of the fractal theory. The boride layers were formed in the AISI M2 steel by applying the paste boriding treatment at temperatures of 1253 and 1273 K and treatment times of 2 and 6 h, while a boron carbide paste thickness of 4 or 5 mm covered the samples surface in order to produce the boron diffusion. The morphology of interfaces formed between FeB and Fe{sub 2}B layers and between Fe{sub 2}B layer and steel substrate was analyzed by the rescaled-range (R/S), root-mean-square (RMS), and Fourier power spectrum (FPS) methods. Moreover, the multi-affine spectra of roughness exponent were obtained by calculating the q-order height-height correlation functions. We found that both interfaces are multi-affine, rather than self-affine. The multi-affine spectra of roughness exponents are found to be different for FeB/Fe{sub 2}B and Fe{sub 2}B/substrate interfaces, but independent on the treatment parameters (boron carbide paste thickness, temperature, and boriding time). Furthermore, we found that the multi-affine spectra of both interfaces behave as it is expected for 'universal multi-fractals' with the Levy index {gamma} = 1, associated with the multiplicative cascades with a log-Cauchy distribution. Furthermore, our data suggest a great homogeneity of the boron diffusion field, characterized by universal fractal dimension D{sub diff} = 2.90 {+-} 0.01. These findings provide a novel insight into the nature of phase formation during the boriding treatment.

  14. Roughness coefficient and its uncertainty in gravel-bed river

    Directory of Open Access Journals (Sweden)

    Ji-Sung Kim

    2010-06-01

    Full Text Available Manning's roughness coefficient was estimated for a gravel-bed river reach using field measurements of water level and discharge, and the applicability of various methods used for estimation of the roughness coefficient was evaluated. Results show that the roughness coefficient tends to decrease with increasing discharge and water depth, and over a certain range it appears to remain constant. Comparison of roughness coefficients calculated by field measurement data with those estimated by other methods shows that, although the field-measured values provide approximate roughness coefficients for relatively large discharge, there seems to be rather high uncertainty due to the difference in resultant values. For this reason, uncertainty related to the roughness coefficient was analyzed in terms of change in computed variables. On average, a 20% increase of the roughness coefficient causes a 7% increase in the water depth and an 8% decrease in velocity, but there may be about a 15% increase in the water depth and an equivalent decrease in velocity for certain cross-sections in the study reach. Finally, the validity of estimated roughness coefficient based on field measurements was examined. A 10% error in discharge measurement may lead to more than 10% uncertainty in roughness coefficient estimation, but corresponding uncertainty in computed water depth and velocity is reduced to approximately 5%. Conversely, the necessity for roughness coefficient estimation by field measurement is confirmed.

  15. Urban Aerodynamic Roughness Length Mapping Using Multitemporal SAR Data

    Directory of Open Access Journals (Sweden)

    Fengli Zhang

    2017-01-01

    Full Text Available Aerodynamic roughness is very important to urban meteorological and climate studies. Radar remote sensing is considered to be an effective means for aerodynamic roughness retrieval because radar backscattering is sensitive to the surface roughness and geometric structure of a given target. In this paper, a methodology for aerodynamic roughness length estimation using SAR data in urban areas is introduced. The scale and orientation characteristics of backscattering of various targets in urban areas were firstly extracted and analyzed, which showed great potential of SAR data for urban roughness elements characterization. Then the ground truth aerodynamic roughness was calculated from wind gradient data acquired by the meteorological tower using fitting and iterative method. And then the optimal dimension of the upwind sector for the aerodynamic roughness calculation was determined through a correlation analysis between backscattering extracted from SAR data at various upwind sector areas and the aerodynamic roughness calculated from the meteorological tower data. Finally a quantitative relationship was set up to retrieve the aerodynamic roughness length from SAR data. Experiments based on ALOS PALSAR and COSMO-SkyMed data from 2006 to 2011 prove that the proposed methodology can provide accurate roughness length estimations for the spatial and temporal analysis of urban surface.

  16. Simulation of shear and turbulence impact on wind turbine power performance

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, R.; Courtney, M.S.; Larsen, T.J.; Paulsen, U.S.

    2010-01-15

    Aerodynamic simulations (HAWC2Aero) were used to investigate the influence of the speed shear, the direction shear and the turbulence intensity on the power output of a multi-megawatt turbine. First simulation cases with laminar flow and power law wind speed profiles were compared to the case of a uniform inflow. Secondly, a similar analysis was done for cases with direction shear. In each case, we derived a standard power curve (function of the wind speed at hub height) and power curves obtained with various definitions of equivalent wind speed in order to reduce the scatter due to shear. Thirdly, the variations of the power output and the power curve were analysed for various turbulence intensities. Furthermore, the equivalent speed method was successfully tested on a power curve resulting from simulations cases combining shear and turbulence. Finally, we roughly simulated the wind speed measurements we may get from a LIDAR mounted on the nacelle of the turbine (measuring upwind) and we investigated different ways of deriving an equivalent wind speed from such measurements. (author)

  17. Modelling the Shear Behaviour of Clean Rock Discontinuities Using Artificial Neural Networks

    Science.gov (United States)

    Dantas Neto, Silvrano Adonias; Indraratna, Buddhima; Oliveira, David Américo Fortuna; de Assis, André Pacheco

    2017-07-01

    Since the mechanical behaviour of rock masses is influenced by the shear behaviour of their discontinuities, analytical models are being developed to describe the shear behaviour of rock discontinuities. The aim of this paper is to present a model to predict the shear behaviour of clean rock discontinuities developed by using artificial neural networks (ANN), as an alternative to the existing analytical models which sometimes require certain parameters obtained from large-scale laboratory tests which are not always available. Results from direct shear tests on different boundary conditions and types of discontinuities have been used to develop this ANN model, whose input parameters contain the boundary normal stiffness, the initial normal stress, the joint roughness coefficient, the compressive strength of the intact rock, the basic friction angle and the horizontal displacement of a joint. This proposed ANN model fits the experimental data better than some existing analytical models, and it can satisfactorily describe how governing parameters influence the shear behaviour of clean rock discontinuities. This paper also presents a practical application where the proposed ANN model is used to analyse the stability of a rock slope.

  18. Shear viscosity of two-flavor inhomogenous color superconducting quark matter

    Science.gov (United States)

    Sarkar, Sreemoyee; Sharma, Rishi

    2017-11-01

    We present the first calculation of the shear viscosity for two-flavor plane wave (FF) color superconducting quark matter. This is a member of the family of crystalline color superconducting phases of dense quark matter that may be present in the cores of neutron stars. The paired quarks in the FF phase feature gapless excitations on surfaces of crescent-shaped blocking regions in momentum space and participate in transport. We calculate their contribution to the shear viscosity. We also note that the transverse t1 , t2, t3 gluons which are undamped in the 2SC lead to dynamic screening in the FF phase. The exchange of these gluons is the most important mechanism of the scattering of the paired quarks. We find that the shear viscosity of the paired quarks is roughly a factor of 100 smaller compared to the shear viscosity of unpaired quark matter even though their spectrum is ungapped. Therefore in the two-flavor FF phase, the unpaired quarks and the electrons give the shear viscosity of the two-flavor FF phase to a very good approximation. Our results may have implications for the damping of r -modes in rapidly rotating, cold neutron stars.

  19. AN EXPERIMENTAL STUDY OF THE STABILITY OF VESSEL-SPANNING BUBBLES IN CYLINDRICAL & ANNULAR & OBROUND & AND CONICAL CONTAINERS

    Energy Technology Data Exchange (ETDEWEB)

    DHALIWAL TK

    2010-01-28

    This report provides a summary of experiments that were performed by Fauske & Associates on the stability of vessel-spanning bubbles. The report by Fauske & Associates, An Experimental Study of the Stability of Vessel-Spanning Bubbles in Cylindrical, Annular, Obround and Conical Containers, is included in Appendix A. Results from the experiments confirm that the gravity yield parameter, Y{sub G}, correctly includes container size and can be applied to full-scale containers to predict the possibility of the formation of a stable vessel spanning bubble. The results also indicate that a vessel spanning bubble will likely form inside the STSC for KE, KW, and Settler sludges if the shear strengths of these sludges exceed 1820, 2080, and 2120 Pa, respectively. A passive mechanism installed in the STSC is effective at disrupting a rising sludge plug and preventing the sludge from plugging the vent filter or being forced out of the container. The Sludge Treatment Project for Engineered Container and Settler Sludge (EC/ST) Disposition Subproject is being conducted in two phases. Phase 1 of the EC/ST Disposition Subproject will retrieve the radioactive sludge currently stored in the K West (KW) Basin into Sludge Transport and Storage Containers (STSCs) and transport the STSCs to T-Plant for interim storage. Phase 2 of the EC/ST Disposition Subproject will retrieve the sludge from interim storage, treat and package sludge for disposal at the Waste Isolation Pilot Plant. The STSC is a cylindrical container; similar to previously used large diameter containers. A STSC (Figure 1) with a diameter of 58 inches will be used to transport KE and KW originating sludge (located in Engineered Containers 210, 220, 240, 250, and 260) to T-Plant. A STSC with an annulus (Figure 2) will be used to transport Settler Tank sludge, located in Engineered Container 230. An obround small canister design was previously considered to retrieve sludge from the basin. The obround design was selected in

  20. Turbulent kinetic energy budget in the boundary layer developing over an urban-like rough wall using PIV

    Science.gov (United States)

    Blackman, Karin; Perret, Laurent; Calmet, Isabelle; Rivet, Cédric

    2017-08-01

    In the present work, a boundary layer developing over a rough-wall consisting of staggered cubes with a plan area packing density λp = 25% is studied within the wind tunnel using Particle Image Velocimetry (PIV) to investigate the Turbulent Kinetic Energy (TKE) budget. To access the full TKE budget, an estimation of the dissipation (ɛ) using both the transport equation of the resolved-scale kinetic energy and Large-Eddy (LE) PIV models based on the use of a subgrid-scale model following the methodology used in large-eddy simulations is employed. A low-pass filter, larger than the Taylor microscale, is applied to the data prior to the computation of the velocity gradients ensuring a clear cutoff in the inertial range where the models are valid. The presence of the cube roughness elements has a significant influence on the TKE budget due to the region of strong shear that develops over the cubes. The shear layer is shown to produce and dissipate energy, as well as transport energy through advection, turbulent transport, and pressure transport. The recirculation region that forms through the interaction of the shear layer and the canopy layer, which is the region below the height of the cube roughness, creates rapid longitudinal evolution of the mean flow thereby inducing weak production. Finally, through stochastic estimation of the conditional average, it is shown that localized regions of backscatter (energy transfer from unresolved to resolved scales) and forward scatter (energy transfer from resolved to unresolved scales) occur as a result of coherent vortical structures.