WorldWideScience

Sample records for biological horizontal cylinder

  1. Conjugate natural convection between horizontal eccentric cylinders

    Science.gov (United States)

    Nasiri, Davood; Dehghan, Ali Akbar; Hadian, Mohammad Reza

    2016-06-01

    This study involved the numerical investigation of conjugate natural convection between two horizontal eccentric cylinders. Both cylinders were considered to be isothermal with only the inner cylinder having a finite wall thickness. The momentum and energy equations were discretized using finite volume method and solved by employing SIMPLER algorithm. Numerical results were presented for various solid-fluid conductivity ratios (KR) and various values of eccentricities in different thickness of inner cylinder wall and also for different angular positions of inner cylinder. From the results, it was observed that in an eccentric case, and for KR 10 value caused an increase in overline{{K_{eq} }} . It was also concluded that in any angular position of inner cylinder, the value of overline{{K_{eq} }} increased with increase in the eccentricity.

  2. Maximal liquid bridges between horizontal cylinders

    OpenAIRE

    Cooray, Himantha; Huppert, Herbert E.; Neufeld, Jerome A

    2016-01-01

    We investigate two-dimensional liquid bridges trapped between pairs of identical horizontal cylinders. The cylinders support forces due to surface tension and hydrostatic pressure which balance the weight of the liquid. The shape of the liquid bridge is determined by analytically solving the nonlinear Laplace-Young equation. Parameters that maximize the trapping capacity (defined as the cross-sectional area of the liquid bridge) are then determined. The results show that these parameters can ...

  3. Performance of a Horizontal Triple Cylinder Type Pulping Machine

    OpenAIRE

    Sukrisno Widyotomo; H. Ahmad; S.T. Soekarno; Sri Mulato

    2011-01-01

    Pulping is one important step in wet coffee processing method. Pulping process usually uses a machine which constructed by wood or metal materials. A horizontal single cylinder type of fresh coffee cherries pulping machine is the most popular machine in coffee processing. One of the weaknesses of a horizontal single cylinder type of fresh coffee cherries pulping machine is higher in broken beans. Broken bean is one of mayor aspects in defect system that contribute to low quality. Indonesian C...

  4. Transport coefficients for low and high-rate mass transfer along a biological horizontal cylinder Coeficientes de transporte para baixas e altas taxas de transferência de massa ao longo de um cilindro biológico horizontal

    Directory of Open Access Journals (Sweden)

    Alberto A. Barreto

    2006-06-01

    Full Text Available Knowledge of heat and mass transfer coefficients is essential for drying simulation studies or design of food and grain thermal processes, including drying. This work presents the full development of a segregated finite element method to solve convection-diffusion problems. The developed scheme allows solving the incompressible, steady-state Navier-Stokes equations and convective-diffusive problems with temperature and moisture dependent properties. The problem of simultaneous energy, momentum and species transfer along an infinite, horizontal cylinder under drying conditions in forced convection is presented, considering conditions normally found in biological material thermal treatment or drying. Numerical results for Nusselt and Sherwood numbers were compared against available empirical expressions; the results agreed within the associated experimental errors. For high rate mass transport processes, the proposed methodology allows to simulate drying conditions involving wall convective mass flux by a simple inclusion of the appropriated boundary conditions.O conhecimento dos coeficientes de transferência de calor e massa é essencial para o estudo de simulação de secagem e para o projeto de processamento térmico de grãos e alimentos, inclusive secagem. Este trabalho apresenta o desenvolvimento completo de um método de elementos finitos segregado para resolver problemas de convecção-difusão. O esquema desenvolvido permite que se resolvam as equações de Navier-Stokes incompressíveis em regime permanente, além de problemas convectivos-difusivos com propriedades dependentes da temperatura e da umidade. Apresenta-se o problema de transferência simultânea de energia, momentum e espécies ao longo de um cilindro horizontal, infinito sob condições de secagem em convecção forçada, considerando-se condições normalmente encontradas em tratamento térmico ou secagem de material biológico. Compararam-se resultados numéricos para

  5. Free Surface Wave Interaction with a Horizontal Cylinder

    Science.gov (United States)

    Oshkai, P.; Rockwell, D.

    1999-10-01

    Classes of vortex formation from a horizontal cylinder adjacent to an undulating free-surface wave are characterized using high-image-density particle image velocimetry. Instantaneous representations of the velocity field, streamline topology and vorticity patterns yield insight into the origin of unsteady loading of the cylinder. For sufficiently deep submergence of the cylinder, the orbital nature of the wave motion results in multiple sites of vortex development, i.e., onset of vorticity concentrations, along the surface of the cylinder, followed by distinctive types of shedding from the cylinder. All of these concentrations of vorticity then exhibit orbital motion about the cylinder. Their contributions to the instantaneous values of the force coefficients are assessed by calculating moments of vorticity. It is shown that large contributions to the moments and their rate of change with time can occur for those vorticity concentrations having relatively small amplitude orbital trajectories. In a limiting case, collision with the surface of the cylinder can occur. Such vortex-cylinder interactions exhibit abrupt changes in the streamline topology during the wave cycle, including abrupt switching of the location of saddle points in the wave. The effect of nominal depth of submergence of the cylinder is characterized in terms of the time history of patterns of vorticity generated from the cylinder and the free surface. Generally speaking, generic types of vorticity concentrations are formed from the cylinder during the cycle of the wave motion for all values of submergence. The proximity of the free surface, however, can exert a remarkable influence on the initial formation, the eventual strength, and the subsequent motion of concentrations of vorticity. For sufficiently shallow submergence, large-scale vortex formation from the upper surface of the cylinder is inhibited and, in contrast, that from the lower surface of the cylinder is intensified. Moreover

  6. Experimental Study on Natural Convection Heat Transfer From two Parallel Horizontal Cylinders in Horizontal Cylindrical Enclosure

    Directory of Open Access Journals (Sweden)

    Ahmed T. Ahmed

    2013-05-01

    Full Text Available  An experimental study on natural convection heat transfer from two parallel horizontal cylinders in horizontal cylindrical enclosure was carried out under condition of constant surfaces temperature for two cylinders and cylindrical enclosure. The study included the effect of Rayleigh number, rotation angle that represent the confined angle between the passing horizontal plane in cylindrical enclosure center and passing line in two cylinders centers, and the spaces between two cylinders on their heat loss ability.39An experimental set-up was used for this purpose which consist watercontainer, test section which is formed of plastic cylinder that represent the cylindrical enclosure, and two heating elements which are formed of two copper cylinders with (19 mm in diameters heated internally by electrical sources that represents transfer and heat loss elements through this set-up.      The experiments were done at the range of Rayleigh number between ( , cylinders rotation angle at ( , and spacing ratio at ( .     The study showed that the ability of heat loss from two cylinders is a function of Rayleigh number, cylinders rotation angle, and the spaces between them. This ability is increased by increasing of Rayleigh number and it was showed that this ability reaches maximum value at the first cylinder ( and minimum value at the second cylinder ( at spacing ratio (S/D=3 and rotation angle ( for the first and ( for the second cylinder respectively.      The effective variables on natural convection heat transfer from the above two cylinders are related by two correlating equations, each one explains dimensionless relation of heat transfer from each cylinder that represented by Nusselt number against Rayleigh number, rotation angle, and the spacing ratio between two cylinders

  7. Performance of a Horizontal Triple Cylinder Type Pulping Machine

    Directory of Open Access Journals (Sweden)

    Sukrisno Widyotomo

    2011-05-01

    Full Text Available Pulping is one important step in wet coffee processing method. Pulping process usually uses a machine which constructed by wood or metal materials. A horizontal single cylinder type of fresh coffee cherries pulping machine is the most popular machine in coffee processing. One of the weaknesses of a horizontal single cylinder type of fresh coffee cherries pulping machine is higher in broken beans. Broken bean is one of mayor aspects in defect system that contribute to low quality. Indonesian Coffee and Cocoa Research Institute has designed and tested a horizontal double cylinder type of fresh coffee cherries pulping machine which resulted in 12.6—21.4% of broken beans. To reduce percentage of broken beans, Indonesian Coffee and Cocoa Research Institute has developed and tested a horizontal triple cylinder type of fresh coffee cherries pulping machine. Material tested was fresh mature Robusta coffee cherries, 60—65% (wet basis moisture content; has classified on 3 levels i.e. unsorted, small and medium, and clean from metal and foreign materials. The result showed that the machine produced 6,340 kg/h in optimal capacity for operational conditions, 1400 rpm rotor rotation speed for unsorted coffee cherries with composition 55.5% whole parchment coffee, 3.66% broken beans, and 1% beans in wet skin.Key words : coffee, pulp, pulper, cylinder, quality.

  8. Qualitative Analysis of Coating Flows on a Rotating Horizontal Cylinder

    Directory of Open Access Journals (Sweden)

    Marina Chugunova

    2012-01-01

    Full Text Available We consider a nonlinear 4th-order degenerate parabolic partial differential equation that arises in modelling the dynamics of an incompressible thin liquid film on the outer surface of a rotating horizontal cylinder in the presence of gravity. The parameters involved determine a rich variety of qualitatively different flows. We obtain sufficient conditions for finite speed of support propagation and for waiting time phenomena by application of a new extension of Stampacchia's lemma for a system of functional equations.

  9. Low volume fraction rimming flow in a rotating horizontal cylinder

    Science.gov (United States)

    Chen, Po-Ju; Tsai, Yu-Te; Liu, Ta-Jo; Wu, Ping-Yao

    2007-12-01

    An experimental study was carried out to examine how uniform rimming flow is established for a very small volume fraction of aqueous Newtonian solutions in a partially filled rotating horizontal cylinder. There exists a certain critical volume fraction (Vc) for each solution, where the rotational speed required to achieve uniform rimming flow takes a minimum value. Counterintuitively, it takes greater rotation speeds for both larger and smaller volume fractions than this. Axial instabilities are observed for liquid volume fractions above or below this critical value. For V >Vc the defects are mainly of shark-teeth and turbulent types, while for V speed for V >Vc, but has very little effect for V speed Ω to achieve rimming flow is presented as a function of the dimensionless liquid volume fraction ϕ. The competing effects of fluid inertia and viscous force on rimming flow are demonstrated from a dimensionless plot of Ω versus ϕ.

  10. Natural convection in a horizontal cylinder with axial rotation

    Science.gov (United States)

    Sánchez, Odalys; Mercader, Isabel; Batiste, Oriol; Alonso, Arantxa

    2016-06-01

    We study the problem of thermal convection in a laterally heated horizontal cylinder rotating about its axis. A cylinder of aspect ratio Γ =H /2 R =2 containing a small Prandtl number fluid (σ =0.01 ) representative of molten metals and molten semiconductors at high temperature is considered. We focus on a slow rotation regime (Ω effects of rotation and buoyancy forces are comparable. The Navier-Stokes and energy equations with the Boussinesq approximation are solved numerically to calculate the basic states, analyze their linear stability, and compute several secondary flows originated from the instabilities. Due to the confined cylindrical geometry—the presence of lateral walls and lids—all the flows are completely three dimensional, even the basic steady states. Results characterizing the basic states as the rotation rate increases are presented. As it occurred in the nonrotating case for higher values of the Prandtl number, two curves of steady states with the same symmetric character coexist for moderate values of the Rayleigh number. In the range of Ω considered, rotation has a stabilizing effect only for very small values. As the value of the rotation rate approaches Ω =3.5 and Ω =4.5 , the scenario of bifurcations becomes more complex due to the existence in both cases of very close bifurcations of codimension 2, which in the latter case involve both curves of symmetric solutions.

  11. Performance of a Horizontal Double Cylinder Type of Fresh Coffee Cherries Pulping Machine

    OpenAIRE

    Sukrisno Widyotomo; Sri Mulato; H. Ahmad; S. Soekarno

    2009-01-01

    Pulping is one important step in wet coffee processing method. Usually, pulping process uses a machine which constructed using wood or metal materials. A horizontal single cylinder type coffee pulping machine is the most popular machine in coffee processor and market. One of the weakness of a horizontal single cylinder type coffee pulping machine is high of broken beans. Broken beans is one of major aspect in defect system that result in low quality. Indonesian Coffee and Cocoa Research Insti...

  12. Heat transfer to a horizontal cylinder in a shallow bubble column

    OpenAIRE

    Tow, Emily W.; Lienhard, John H.

    2014-01-01

    Heat transfer coefficient correlations for tall bubble columns are unable to predict heat transfer in shallow bubble columns, which have unique geometry and fluid dynamics. In this work, the heat transfer coefficient is measured on the surface of a horizontal cylinder immersed in a shallow air–water bubble column. Superficial velocity, liquid depth, and cylinder height and horizontal position with respect to the sparger orifices are varied. The heat transfer coefficient is found to increase w...

  13. Natural convection heat transfer on two horizontal cylinders in liquid sodium

    Energy Technology Data Exchange (ETDEWEB)

    Hata, K.; Shiotsu, M.; Takeuchi, Y. [Institute of Atomic Energy, Kyoto Univ. (Japan)] [and others

    1995-09-01

    Natural convection heat transfer on two horizontal 7.6 mm diameter test cylinders assembled with the ratio of the distance between each cylinder axis to the cylinder diameter, S/D, of 2 in liquid sodium was studied experimentally and theoretically. The heat transfer coefficients on the cylinder surface due to the same heat inputs ranging from 1.0 X 10{sup 7} to 1.0 x 10{sup 9} W/m{sup 3} were obtained experimentally for various setting angeles, {gamma}, between vertical direction and the plane including both of these cylinder axis over the range of zero to 90{degrees}. Theoretical equations for laminar natural convection heat transfer from the two horizontal cylinders were numerically solved for the same conditions as the experimental ones considering the temperature dependence of thermophysical properties concerned. The average Nusselt numbers, Nu, values on the Nu versus modified Rayleigh number, R{sub f}, graph. The experimental values of Nu for the upper cylinder are about 20% lower than those for the lower cylinder at {gamma} = 0{degrees} for the range of R{sub f} tested here. The value of Nu for the upper cylinder becomes higher and approaches that for the lower cylinder with the increase in {gamma} over range of 0 to 90{degrees}. The values of Nu for the lower cylinder at each {gamma} are almost in agreement with those for a single cylinder. The theoretical values of Nu on two cylinders except those for R{sub f}<4 at {gamma} = 0{degrees} are in agreement with the experimental data at each {gamma} with the deviations less than 15%. Correlations for Nu on the upper and lower cylinders were obtained as functions of S/D and {gamma} based n the theoretical solutions for the S/D ranged over 1.5 to 4.0.

  14. Interaction of oblique waves with an array of long horizontal circular cylinders

    Institute of Scientific and Technical Information of China (English)

    NG; Chiu-On

    2007-01-01

    The scattering and radiations of linear oblique waves by multiple long horizontal circular cylinders submerged in water of finite depth are investigated using the multipole expansion method. Analytical expressions for the diffracted and radiated potentials are given as a linear combination of infinite multipoles. The unknown coefficients in the expressions are determined by using the addition theorem of the Bessel function and the cylinder boundary conditions. Also analytical expressions for wave forces, hydrodynamic coefficients and reflection and transmission coeffi-cients are derived. The present analytical solution is verified through the boundary element method and applied to investigate three different cases of the interaction of oblique waves with multiple submerged horizontal circular cylinders. The results show that the number of cylinders, the arrangement and spacing between cylinders play an important role in wave forces, hydrodynamic coefficients and reflection and transmission coefficients. Some interesting and important phenomena are ob-served in numerical experiments.

  15. Interaction of oblique waves with an array of long horizontal circular cylinders

    Institute of Scientific and Technical Information of China (English)

    SHEN YongMing; ZHENG YongHong; NG Chiu-On

    2007-01-01

    The scattering and radiations of linear oblique waves by multiple long horizontal circular cylinders submerged in water of finite depth are investigated using the multipole expansion method. Analytical expressions for the diffracted and radiated potentials are given as a linear combination of infinite multipoles. The unknown coefficients in the expressions are determined by using the addition theorem of the Bessel function and the cylinder boundary conditions. Also analytical expressions for wave forces, hydrodynamic coefficients and reflection and transmission coefficients are derived. The present analytical solution is verified through the boundary element method and applied to investigate three different cases of the interaction of oblique waves with multiple submerged horizontal circular cylinders. The results show that the number of cylinders, the arrangement and spacing between cylinders play an important role in wave forces, hydrodynamic coefficients and reflection and transmission coefficients. Some interesting and important phenomena are observed in numerical experiments.

  16. Flow structure from a horizontal cylinder coincident with a free surface in shallow water flow

    Directory of Open Access Journals (Sweden)

    Kahraman Ali

    2012-01-01

    Full Text Available Vortex formation from a horizontal cylinder coincident with a free surface of a shallow water flow having a depth of 25.4 [mm] was experimentally investigated using the PIV technique. Instantaneous and time-averaged flow patterns in the wake region of the cylinder were examined for three different cylinder diameter values under the fully developed turbulent boundary layer condition. Reynolds numbers were in the range of 1124£ Re£ 3374 and Froude numbers were in the range of 0.41 £ Fr £ 0.71 based on the cylinder diameter. It was found that a jet-like flow giving rise to increasing the flow entrainment between the core and wake regions depending on the cylinder diameter was formed between the lower surface of the cylinder and bottom surface of the channel. Vorticity intensity, Reynolds stress correlations and the primary recirculating bubble lengths were grown to higher values with increasing the cylinder diameter. On the other hand, in the case of the lowest level of the jet-like flow emanating from the beneath of the smallest cylinder, the variation of flow characteristics were attenuated significantly in a shorter distance. The variation of the reattachment location of the separated flow to the free-surface is a strong function of the cylinder diameter and the Froude number.

  17. Flow structure from a horizontal cylinder coincident with a free surface in shallow water flow

    OpenAIRE

    Kahraman Ali; Özgören Muammer; Şahin Beşir

    2012-01-01

    Vortex formation from a horizontal cylinder coincident with a free surface of a shallow water flow having a depth of 25.4 [mm] was experimentally investigated using the PIV technique. Instantaneous and time-averaged flow patterns in the wake region of the cylinder were examined for three different cylinder diameter values under the fully developed turbulent boundary layer condition. Reynolds numbers were in the range of 1124£ Re£ 3374 and Froude numbers were in the range of 0.41 £ Fr £ ...

  18. Movement of a horizontal vortex ring in a circular cylinder

    International Nuclear Information System (INIS)

    In this paper, we report the numerical and experimental solutions of the vortical flows driven by an impingement of fluid from the bottom wall of a circular cylinder. We managed to visualize successfully the flow pattern shown on the vertical plane through the container axis. The numerical results are shown to compare well with the experimental results for the case of infinity Rossby number. The satisfactory agreement between the two results was possible when in the numerics the free surface was treated as a solid wall so that a no-slip condition was applied on the surface. The numerical solutions reveal that inertial oscillation plays an important role at small Rossby numbers, or at a large background rotation

  19. Flow film boiling heat transfer for subcooled liquids flowing upward perpendicular to single horizontal cylinders

    International Nuclear Information System (INIS)

    The knowledge of flow film boiling heat transfer on a horizontal cylinder in various liquids flowing upward perpendicular to the cylinder is important as the database for the safety evaluation of the accidents such as rapid power burst and pressure reduction in the nuclear power plants. Flow film boiling heat transfer from single horizontal cylinders in water and Freon-113 flowing upward perpendicular to the cylinder under subcooled conditions was measured under wide experimental conditions. The flow velocities ranged from 0 to 1 m/s, the system pressures ranged from 100 to 500 kPa, and the surface superheats were raised up to 800 K for water and 400 K for Freon-113, respectively. Platinum horizontal cylinders with diameters ranging from 0.7 to 5 mm were used as the test heaters. The test heater was heated by direct electric current. The experimental data of film boiling heat transfer coefficients show that they increase with the increase of flow velocity, liquid subcooling, system pressure and with the decrease of cylinder diameter. Based on the experimental data, a correlation for subcooled flow film boiling heat transfer including the effects of liquid subcooling and radiation was presented, which can describe the experimental data obtained within 20% for the flow velocities below 0.7 m/s, and within -30% to +20% for the higher flow velocities. The correlation also predicted well the data by Shigechi (1983), Motte and Bromley (1957), and Sankaran and Witte (1990) obtained for the larger diameter cylinders and higher flow velocities in various liquids at the pressures of near atmospheric. The Shigechi's data were in the range from about -20% to +15%, the data of Motte and Bromley were about 30%,and the data of Sankaran and Witte were within +20 % of the curves given by the corresponding predicted values. (authors)

  20. Water Entry and Exit of Horizontal Cylinder in Free Surface Flow

    International Nuclear Information System (INIS)

    This paper describes two-dimensional numerical simulations of the water entry and exit of horizontal circular cylinder at constant velocity. The deformation of free surface is described by Navier-Stokes (N S) equations of incompressible and viscous fluid with additional transport equation of the volume-of-fluid (VOF). The motion of the cylinder is modeled by the associated momentum source term implemented in the Phoenicis (Parabolic Hyperbolic Or Elliptic Numerical Integration Code Series) code. The domain is discretized by a fixed Cartesian grid using a finite volume method and the cylinder is represented and cut cell method. The simulated results are compared with the numerical results of Lin (2007). This comparison shows good agreement in terms of free surface evolution for water exit and sinking. However, for water entry, the jet flow simulated by Lin is not reproduced. The free surface deformation around the cylinder in downward direction is accurately predicted

  1. A FINITE ELEMENT ANALYSIS OF HYDRAULIC CYLINDER OF LINEAR HYDRAULIC MOTOR FROM HORIZONTAL HYDRAULIC PRESS – 2 MN

    OpenAIRE

    ŢĂLU D.L.MIHAI; ŢĂLU D.L. ŞTEFAN

    2010-01-01

    This paper analyse through the finite element method (FEM) the hydraulic cylinder of linear hydraulic motor from horizontal Hydraulic Press – 2 MN. The analysis of the hydraulic cylinder of linear hydraulic motor from horizontal Hydraulic Press – 2 MN was made for determination of displacements and deformations. A three-dimensional model of the hydraulic cylinder with a complex geometry was generated based on the designed data. Finite element analysis was performed using COSMOSWorks software....

  2. Self-weight loading of horizontal hydraulic cylinders with axial load

    Science.gov (United States)

    Hale, J. M.; Sim, Ee Yu

    2016-05-01

    An iterative matrix method is described to determine the deformed shape of a horizontal stepped tube with large axial load, representing a heavy hydraulic cylinder. The method is applicable to both simply supported (pinned-pinned) and clamped-clamped end constraints. The clamped-clamped case is extended to include rotational compliance in the clamps. Using this analysis, radial loads on the piston seals of the cylinder are determined. Comparison is made between the seal loading of a typical large cylinder in pinned-pinned and clamped-clamped configurations, respectively. It is shown that the seal loading can be considerably reduced by the use of the clamped-clamped configuration provided the ends can be well aligned, but that the load is sensitive to angular misalignment.

  3. Natural convection around a horizontal cylinder near an adiabatic cover wall

    International Nuclear Information System (INIS)

    The main objective of this work was to determine numerically the influence of the proximity of an adiabatic top surface over the natural convective coefficient, around an isothermal horizontal cylinder in atmospheric air. The local and mean Nusselt numbers around the cylinder were obtained through a numerical solution of the dimensionless equations for two-dimensional laminar natural convection flow at steady state in Cartesian coordinates, using the ω, ψ, Τ, formulation. The software was run for different Rayleigh values (102 5) and distances cylinder-cover wall (0.55 < L/D < 2.5). The results allow concluding that the top adiabatic surface diminishes the convective coefficient in comparison with the value obtained using an infinite medium as boundary condition, it occurs when L/D<2, at any Rayleigh number value. (authors)

  4. Numerical and experimental investigation of natural convection from horizontal heated cylinders

    OpenAIRE

    2012-01-01

    List of papers. Papers I-V are removed from the thesis due to copyright restrictions. Paper I: Grafsrønningen S., Jensen A. & Reif. B.A.P. 2011. PIV investigation of buoyant plume from natural convection heat transfer above a horizontal heated cylinder. International Journal of Heat and Mass Transfer 54, 4975 4987. doi:10.1016/j.ijheatmasstransfer.2011.07.011 Paper II: Grafsrønningen S. & Jensen A. 2012. Simultaneous PIV/LIF measurements of a transitional buoyant plume above a horizontal cy...

  5. Concept of Hydrodynamic Load Analysis of Fixed Jacket Structure – An Overview of Horizontal Cylinder

    Directory of Open Access Journals (Sweden)

    Aliyu Baba

    2014-04-01

    Full Text Available This paper focuses on the analysis of hydrodynamic loads on fixed offshore structures (horizontal cylinder that are operating in shallow water and are often subjected to huge wave loading. For the purpose of this study, linear (Airy wave theory was adopted together with the application of (21 in the load computation. The loads for six different sea states were computed using spread sheet for the following values of time t = 0, T/4, T/2.

  6. Natural convection heat transfer from horizontal rod bundles in liquid sodium. Part 1. Correlations for two parallel horizontal cylinders based on experimental and theoretical results

    International Nuclear Information System (INIS)

    Natural convection heat transfer coefficients on two parallel horizontal test cylinders in liquid sodium were obtained experimentally and theoretically for various setting angles, γ, between vertical direction and the plane including both of these cylinders' axes, over the range of 0°–90°. Both test cylinders are 7.6 mm in diameter and 50 mm in heated length with the ratio of the distance between each cylinder axis to the cylinder diameter, S/D, of 2. Theoretical equations for laminar natural convection heat transfer from the two horizontal cylinders were numerically solved for the same conditions as the experimental ones. The average Nusselt numbers Nu on the cylinders obtained experimentally were compared with the corresponding theoretical values on the Nu versus modified Rayleigh number Rf [= Gr*Pr2/(4 + 9Pr1/2 + 10Pr)] graph. The experimental values of Nu for the upper cylinder are about 20% lower than those for the lower cylinder at γ = 0° for the range of Rf tested here. The value of Nu for the upper cylinder becomes higher and approaches that for the lower cylinder with the increase in γ over the range of 0°–90°: the values for each cylinder agree with each other at γ = 90°. The values of Nu for the lower cylinder at each γ are almost in agreement with those for a single cylinder. The theoretical values of Nu on two cylinders except those for Rf < 4 at γ = 0° are in agreement with the experimental data at each γ with the deviations less than 15%. Correlations for two cylinders were obtained as functions of S/D and γ based on the theoretical solutions. A combined correlation for multi-cylinders in a vertical array based on the correlations for two cylinders was developed. The values by the correlation agree with the theoretical solution for the multi-cylinders for Rf ranging from 4.7 to 63 within 10% difference. (author)

  7. Performance of a Horizontal Double Cylinder Type of Fresh Coffee Cherries Pulping Machine

    Directory of Open Access Journals (Sweden)

    Sukrisno Widyotomo

    2009-05-01

    Full Text Available Pulping is one important step in wet coffee processing method. Usually, pulping process uses a machine which constructed using wood or metal materials. A horizontal single cylinder type coffee pulping machine is the most popular machine in coffee processor and market. One of the weakness of a horizontal single cylinder type coffee pulping machine is high of broken beans. Broken beans is one of major aspect in defect system that result in low quality. Indonesian Coffee and Cocoa Research Institute has designed and tested a horizontal double cylinder type coffee pulping machine. Material tested is Robusta cherry, mature, 60—65% (wet basis moisture content, which size compostition of coffee cherries was 50.8% more than 15 mm diameter, 32% more than 10 mm diameter, and 16.6% to get through 10 mm hole diameter; 690—695 kg/m3 bulk density, and clean from methal and foreign materials. The result showed that this machine has 420 kg/h optimal capacity in operational conditions, 1400 rpm rotor rotation speed for unsorted coffee cherries with composition 53.08% whole parchment coffee, 16.92% broken beans, and 30% beans in the wet skin. For small size coffee cherries, 603 kg/h optimal capacity in operational conditions, 1600 rpm rotor rotation speed with composition 51.30% whole parchment coffee, 12.59% broken beans, and 36.1% beans in the wet skin. Finally, for medium size coffee cherries, 564 kg/h optimal capacity in operational conditions, 1800 rpm rotor rotation speed with composition 48.64% whole parchment coffee, 18.5% broken beans, and 32.86% beans in the wet skin.Key words : coffee, pulp, pulper, cylinder, quality.

  8. Rivulet flow round a horizontal cylinder subject to a uniform surface shear stress

    KAUST Repository

    Paterson, C.

    2014-09-14

    © 2014 © The Author, 2014. Published by Oxford University Press; all rights reserved. For Permissions, please email: journals.permissions@oup.com. The steady flow of a slowly varying rivulet with prescribed flux in the azimuthal direction round a large stationary horizontal cylinder subject to a prescribed uniform azimuthal surface shear stress is investigated. In particular, we focus on the case where the volume flux is downwards but the shear stress is upwards, for which there is always a solution corresponding to a rivulet flowing down at least part of one side of the cylinder. We consider both a rivulet with constant non-zero contact angle but slowly varying width (that is, de-pinned contact lines) and a rivulet with constant width but slowly varying contact angle (that is, pinned contact lines), and show that they have qualitatively different behaviour. When shear is present, a rivulet with constant non-zero contact angle can never run all the way from the top to the bottom of the cylinder, and so we consider the scenario in which an infinitely wide two-dimensional film of uniform thickness covers part of the upper half of the cylinder and \\'breaks\\' into a single rivulet with constant non-zero contact angle. In contrast, a sufficiently narrow rivulet with constant width can run all the way from the top to the bottom of the cylinder, whereas a wide rivulet can do so only if its contact lines de-pin, and so we consider the scenario in which the contact lines of a wide rivulet de-pin on the lower half of the cylinder.

  9. Numerical simulation of vibration of horizontal cylinder induced by progressive waves

    Science.gov (United States)

    Chern, Ming-Jyh; Odhiambo, E. A.; Horng, Tzyy-Leng; Borthwick, A. G. L.

    2016-02-01

    Maritime structures often comprise cylinders of small diameter relative to the prevailing wave length. This paper describes the direct forcing immersed boundary simulation of the hydroelastic behaviour of a rigid, horizontal circular cylinder in regular progressive waves. Fluid motions are numerically solved by the full Navier-Stokes equations, and the free surface by the volume-of-fluid method. The Reynolds number Re = 110, Keulegan-Carpenter number KC = 10, Froude number Fr = 0.69 and Ursell number U rs ≈ 12. A single-degree-of-freedom model is used for the elastically mounted cylinder. Velocity profiles for the stationary cylinder case have been successfully validated using experimental results. The frequency response for reduced velocities 4.5\\lt {U}R*\\lt 5.3 have been compared with theoretical data. Three transverse vibration regimes are identified: lower beating (4\\lt {U}R*\\lt 4.5); lock-in (4.7\\lt {U}R*\\lt 4.8); and upper beating (5\\lt {U}R*\\lt 10) modes. The lower and upper beating regimes exhibit varying amplitude response. The lock-in mode represents the region of fixed and maximum response. The lower beating and lock-in modes have peaks at a common vibration to wave frequency ratio {f}{{w}}* = 2. For the upper beating mode, {f}{{w}}* = 1, except for {U}R*=10 when {f}{{w}}* = 2.

  10. Mixed convection heat transfer from vertically separated horizontal cylinders within confining walls

    Energy Technology Data Exchange (ETDEWEB)

    Lacroix, M.; Carrier, R. [Univ. de Sherbrooke, Quebec (Canada). Dept. de Genie Mecanique

    1995-04-01

    This paper presents a numerical study of mixed connection heat transfer around two vertically separated horizontal cylinders within confining adiabatic walls. Parametric simulations are performed to assess the effect of the cylinder spacing B / D, of the distance between the parallel plates L / D, and of the Gr / Re{sup 2} ratio on the heat transfer and fluid flow. Results have shown that for L / D {>=} 1.5, increasing B / D increases, in all cases, the overall heat transfer coefficient. On the other hand, an enlargement of the channel decreases the overall Nusselt number for L / D {<=} 3.0 and Gr / Re {sup 2} {<=} 1.0 and increases it for L / D {<=}3.0 and Gr / Re{sup 2} {>=} 10.0. For L / D > 3.0 the effect of the parallel adiabatic walls on the heat transfer is imperceptible regardless of the magnitude of the Gr / Re{sup 2} ratio.

  11. Mixed convection heat transfer from vertically separated horizontal cylinders within confining walls

    International Nuclear Information System (INIS)

    This paper presents a numerical study of mixed connection heat transfer around two vertically separated horizontal cylinders within confining adiabatic walls. Parametric simulations are performed to assess the effect of the cylinder spacing B / D, of the distance between the parallel plates L / D, and of the Gr / Re2 ratio on the heat transfer and fluid flow. Results have shown that for L / D ≥ 1.5, increasing B / D increases, in all cases, the overall heat transfer coefficient. On the other hand, an enlargement of the channel decreases the overall Nusselt number for L / D ≤ 3.0 and Gr / Re 2 ≤ 1.0 and increases it for L / D ≤3.0 and Gr / Re2 ≥ 10.0. For L / D > 3.0 the effect of the parallel adiabatic walls on the heat transfer is imperceptible regardless of the magnitude of the Gr / Re2 ratio

  12. CFD Calculation of Internal Natural Convection in the Annulus between Horizontal Concentric Cylinders

    Energy Technology Data Exchange (ETDEWEB)

    N.D. Francis, Jr; M.T. Itamura; S.W. Webb; D.L. James

    2002-10-01

    The objective of this heat transfer and fluid flow study is to assess the ability of a computational fluid dynamics (CFD) code to reproduce the experimental results, numerical simulation results, and heat transfer correlation equations developed in the literature for natural convection heat transfer within the annulus of horizontal concentric cylinders. In the literature, a variety of heat transfer expressions have been developed to compute average equivalent thermal conductivities. However, the expressions have been primarily developed for very small inner and outer cylinder radii and gap-widths. In this comparative study, interest is primarily focused on large gap widths (on the order of half meter or greater) and large radius ratios. From the steady-state CFD analysis it is found that the concentric cylinder models for the larger geometries compare favorably to the results of the Kuehn and Goldstein correlations in the Rayleigh number range of about 10{sup 5} to 10{sup 8} (a range that encompasses the laminar to turbulent transition). For Rayleigh numbers greater than 10{sup 8}, both numerical simulations and experimental data (from the literature) are consistent and result in slightly lower equivalent thermal conductivities than those obtained from the Kuehn and Goldstein correlations.

  13. CFD Calculation of Internal Natural Convection in the Annulus between Horizontal Concentric Cylinders

    International Nuclear Information System (INIS)

    The objective of this heat transfer and fluid flow study is to assess the ability of a computational fluid dynamics (CFD) code to reproduce the experimental results, numerical simulation results, and heat transfer correlation equations developed in the literature for natural convection heat transfer within the annulus of horizontal concentric cylinders. In the literature, a variety of heat transfer expressions have been developed to compute average equivalent thermal conductivities. However, the expressions have been primarily developed for very small inner and outer cylinder radii and gap-widths. In this comparative study, interest is primarily focused on large gap widths (on the order of half meter or greater) and large radius ratios. From the steady-state CFD analysis it is found that the concentric cylinder models for the larger geometries compare favorably to the results of the Kuehn and Goldstein correlations in the Rayleigh number range of about 105 to 108 (a range that encompasses the laminar to turbulent transition). For Rayleigh numbers greater than 108, both numerical simulations and experimental data (from the literature) are consistent and result in slightly lower equivalent thermal conductivities than those obtained from the Kuehn and Goldstein correlations

  14. Natural convection heat transfer for a staggered array of heated, horizontal cylinders within a rectangular enclosure

    International Nuclear Information System (INIS)

    This thesis presents the results of an experimental investigation of natural convection heat transfer in a staggered array of heated cylinders, oriented horizontally within a rectangular enclosure. The main purpose of this research was to extend the knowledge of heat transfer within enclosed bundles of spent nuclear fuel rods sealed within a shipping or storage container. This research extends Canaan's investigation of an aligned array of heated cylinders that thermally simulated a boiling water reactor (BWR) spent fuel assembly sealed within a shipping or storage cask. The results are presented in terms of piecewise Nusselt-Rayleigh number correlations of the form Nu = C(Ra)n, where C and n are constants. Correlations are presented both for individual rods within the array and for the array as a whole. The correlations are based only on the convective component of the heat transfer. The radiative component was calculated with a finite-element code that used measured surface temperatures, rod array geometry, and measured surface emissivities as inputs. The correlation results are compared to Canaan's aligned array results and to other studies of natural convection in horizontal tube arrays

  15. Natural convection heat transfer for a staggered array of heated, horizontal cylinders within a rectangular enclosure

    Energy Technology Data Exchange (ETDEWEB)

    Triplett, C.E.

    1996-12-01

    This thesis presents the results of an experimental investigation of natural convection heat transfer in a staggered array of heated cylinders, oriented horizontally within a rectangular enclosure. The main purpose of this research was to extend the knowledge of heat transfer within enclosed bundles of spent nuclear fuel rods sealed within a shipping or storage container. This research extends Canaan`s investigation of an aligned array of heated cylinders that thermally simulated a boiling water reactor (BWR) spent fuel assembly sealed within a shipping or storage cask. The results are presented in terms of piecewise Nusselt-Rayleigh number correlations of the form Nu = C(Ra){sup n}, where C and n are constants. Correlations are presented both for individual rods within the array and for the array as a whole. The correlations are based only on the convective component of the heat transfer. The radiative component was calculated with a finite-element code that used measured surface temperatures, rod array geometry, and measured surface emissivities as inputs. The correlation results are compared to Canaan`s aligned array results and to other studies of natural convection in horizontal tube arrays.

  16. Numerical study of natural convection in a horizontal cylinder filled with water-based alumina nanofluid

    Science.gov (United States)

    Meng, Xiangyin; Li, Yan

    2015-03-01

    Natural heat convection of water-based alumina (Al2O3/water) nanofluids (with volume fraction 1% and 4%) in a horizontal cylinder is numerically investigated. The whole three-dimensional computational fluid dynamics (CFD) procedure is performed in a completely open-source way. Blender, enGrid, OpenFOAM and ParaView are employed for geometry creation, mesh generation, case simulation and post process, respectively. Original solver `buoyantBoussinesqSimpleFoam' is selected for the present study, and a temperature-dependent solver `buoyantBoussinesqSimpleTDFoam' is developed to ensure the simulation is more realistic. The two solvers are used for same cases and compared to corresponding experimental results. The flow regime in these cases is laminar (Reynolds number is 150) and the Rayleigh number range is 0.7 × 107 ~ 5 × 107. By comparison, the average natural Nusselt numbers of water and Al2O3/water nanofluids are found to increase with the Rayleigh number. At the same Rayleigh number, the Nusselt number is found to decrease with nanofluid volume fraction. The temperature-dependent solver is found better for water and 1% Al2O3/water nanofluid cases, while the original solver is better for 4% Al2O3/water nanofluid cases. Furthermore, due to strong three-dimensional flow features in the horizontal cylinder, three-dimensional CFD simulation is recommended instead of two-dimensional simplifications.

  17. Three-dimensional coating and rimming flow: a ring of fluid on a rotating horizontal cylinder

    KAUST Repository

    Leslie, G. A.

    2013-01-29

    The steady three-dimensional flow of a thin, slowly varying ring of Newtonian fluid on either the outside or the inside of a uniformly rotating large horizontal cylinder is investigated. Specifically, we study \\'full-ring\\' solutions, corresponding to a ring of continuous, finite and non-zero thickness that extends all of the way around the cylinder. In particular, it is found that there is a critical solution corresponding to either a critical load above which no full-ring solution exists (if the rotation speed is prescribed) or a critical rotation speed below which no full-ring solution exists (if the load is prescribed). We describe the behaviour of the critical solution and, in particular, show that the critical flux, the critical load, the critical semi-width and the critical ring profile are all increasing functions of the rotation speed. In the limit of small rotation speed, the critical flux is small and the critical ring is narrow and thin, leading to a small critical load. In the limit of large rotation speed, the critical flux is large and the critical ring is wide on the upper half of the cylinder and thick on the lower half of the cylinder, leading to a large critical load. We also describe the behaviour of the non-critical full-ring solution and, in particular, show that the semi-width and the ring profile are increasing functions of the load but, in general, non-monotonic functions of the rotation speed. In the limit of large rotation speed, the ring approaches a limiting non-uniform shape, whereas in the limit of small load, the ring is narrow and thin with a uniform parabolic profile. Finally, we show that, while for most values of the rotation speed and the load the azimuthal velocity is in the same direction as the rotation of the cylinder, there is a region of parameter space close to the critical solution for sufficiently small rotation speed in which backflow occurs in a small region on the upward-moving side of the cylinder. © 2013

  18. Mixed convection boundary layer flow over a horizontal elliptic cylinder with constant heat flux

    Science.gov (United States)

    Javed, Tariq; Ahmad, Hussain; Ghaffari, Abuzar

    2015-12-01

    Mixed convection boundary layer flow of a viscous fluid over a horizontal elliptic cylinder with a constant heat flux is investigated numerically. The governing partial differential equations are transformed to non-dimensional form and then are solved by an efficient implicit finite different scheme known as Keller-box method. The solutions are expressed in the form of skin friction and Nusselt number, which are plotted against the eccentric angle. The effect of pertinent parameters such as mixed convection parameter, aspect ratio (ratio of lengths of minor axis to major axis), and Prandtl number on skin friction and Nusselt number are illustrated through graphs for both blunt and slender orientations. The increase in the value of mixed convection parameter results in increase in skin friction coefficient and Nusselt number for blunt as well as slender orientations.

  19. Three-dimensional natural convection in a horizontal cylinder subject to mixed boundary conditions

    International Nuclear Information System (INIS)

    Natural convection plays a pivotal role in the overall energy transfer in solar collectors, thermal energy storage systems, nuclear spent fuel cooling with emphasis on the design of shipping casks for the transportation of fuel rods, cooling of electronic equipment, and in inert-gas insulated electrical cables. Numerous studies, both numerical and experimental, have been performed on natural convective heat transfer and fluid flow. In this paper, results of numerical simulations of steady, laminar 3-D natural convection around a square rod placed concentrically in a horizontal cylinder are presented. This problem models the fluid dynamics and heat transfer in a nuclear spent fuel shipping cask in which the inner body represents a light water reactor (LWR) fuel assembly. Throughout this study, the inner and outer boundaries are maintained at constant heat flux and isothermal conditions, respectively. The end boundaries are maintained at adiabatic conditions

  20. Generalized linear stability of non-inertial rimming flow in a rotating horizontal cylinder.

    Science.gov (United States)

    Aggarwal, Himanshu; Tiwari, Naveen

    2015-10-01

    The stability of a thin film of viscous liquid inside a horizontally rotating cylinder is studied using modal and non-modal analysis. The equation governing the film thickness is derived within lubrication approximation and up to first order in aspect ratio (average film thickness to radius of the cylinder). Effect of gravity, viscous stress and capillary pressure are considered in the model. Steady base profiles are computed in the parameter space of interest that are uniform in the axial direction. A linear stability analysis is performed on these base profiles to study their stability to axial perturbations. The destabilizing behavior of aspect ratio and surface tension is demonstrated which is attributed to capillary instability. The transient growth that gives maximum amplification of any initial disturbance and the pseudospectra of the stability operator are computed. These computations reveal weak effect of non-normality of the operator and the results of eigenvalue analysis are recovered after a brief transient period. Results from nonlinear simulations are also presented which also confirm the validity of the modal analysis for the flow considered in this study. PMID:26496740

  1. Numerical study of natural convection in a horizontal cylinder filled with water-based alumina nanofluid.

    Science.gov (United States)

    Meng, Xiangyin; Li, Yan

    2015-01-01

    Natural heat convection of water-based alumina (Al2O3/water) nanofluids (with volume fraction 1% and 4%) in a horizontal cylinder is numerically investigated. The whole three-dimensional computational fluid dynamics (CFD) procedure is performed in a completely open-source way. Blender, enGrid, OpenFOAM and ParaView are employed for geometry creation, mesh generation, case simulation and post process, respectively. Original solver 'buoyantBoussinesqSimpleFoam' is selected for the present study, and a temperature-dependent solver 'buoyantBoussinesqSimpleTDFoam' is developed to ensure the simulation is more realistic. The two solvers are used for same cases and compared to corresponding experimental results. The flow regime in these cases is laminar (Reynolds number is 150) and the Rayleigh number range is 0.7 × 10(7) ~ 5 × 10(7). By comparison, the average natural Nusselt numbers of water and Al2O3/water nanofluids are found to increase with the Rayleigh number. At the same Rayleigh number, the Nusselt number is found to decrease with nanofluid volume fraction. The temperature-dependent solver is found better for water and 1% Al2O3/water nanofluid cases, while the original solver is better for 4% Al2O3/water nanofluid cases. Furthermore, due to strong three-dimensional flow features in the horizontal cylinder, three-dimensional CFD simulation is recommended instead of two-dimensional simplifications. PMID:25852431

  2. Stagnation point flow and heat transfer behavior of Cu-water nanofluid towards horizontal and exponentially stretching/shrinking cylinders

    Science.gov (United States)

    Sulochana, C.; Sandeep, N.

    2016-03-01

    In this study we analyzed the stagnation point flow and heat transfer behavior of Cu-water nanofluid towards horizontal and exponentially permeable stretching/shrinking cylinders in presence of suction/injection, heat source and shape of nanoparticles. The governing boundary layer equations are transformed to nonlinear ordinary differential equations using similarity transformation which are then solved numerically using bvp4c Matlab package. The influence of non-dimensional governing parameters on the flow field and heat transfer characteristics are discussed and presented through graphs and tables. The study indicates that the solutions for the horizontal and exponential cylinders are non-unique and shape of nanoparticles also influences the rate of heat transfer. Comparisons of the present results with existed studies are presented. Present study has an excellent agreement with the existed studies under some special conditions.

  3. Heat transfer in the flow of a cold, two-dimensional draining sheet over a hot, horizontal cylinder

    CERN Document Server

    Shu, Jian-Jun

    2014-01-01

    The paper considers heat transfer characteristics of thin film flow over a hot horizontal cylinder resulting from a cold vertical sheet of liquid falling onto the surface. The underlying physical features of the developing film thickness, velocity and temperature distributions have been illustrated by numerical solutions of high accuracy for large Reynolds numbers using the modified Keller box method. The solutions for film thickness distribution are good agreement with those obtained using the Pohlhausen integral momentum technique thus providing a basic confirmation of the validity of the results presented.

  4. Interaction of Linear Waves with Infinitely Long Horizontal Cylinders Studied by Boundary Element Method

    Institute of Scientific and Technical Information of China (English)

    FENG Bo; ZHENG Yong-hong; YOU Ya-ge; HE Zai-ming

    2007-01-01

    The two-dimensional problems concerning the interaction of linear water waves with cylinders of arbitrary shape in two-layer deep water are investigated by use of the Boundary Integral Equation Method (BIEM). Simpler new expressions for the Green functions are derived, and verified by comparison of results obtained by BIEM with those by an analytical method. Examined are the radiation and scattering of linear waves by two typical configurations of cylinders in two-layer deep water. Hydrodynamic behaviors including hydrodynamic coefficients, wave forces, reflection and transmission coefficients and energies are analyzed in detail, and some interesting physical phenomena are observed.

  5. Mixed convection heat transfer from confined tandem square cylinders in a horizontal channel

    KAUST Repository

    Huang, Zhu

    2013-11-01

    This paper presents a numerical study on the two-dimensional laminar mixed convective flow and heat transfer around two identical isothermal square cylinders arranged in tandem and confined in a channel. The spacing between the cylinders is fixed with four widths of the cylinder and the blockage ratio and the Prandtl number are fixed at 0.1 and 0.7 respectively. The mixed convective flow and heat transfer is simulated by high accuracy multidomain pseudospectral method. The Reynolds number (Re) is studied in the range 80 ≤ Re ≤ 150, the Richardson number (Ri) demonstrating the influence of thermal buoyancy ranges from 0 to 1. Numerical results reveal that, with the thermal buoyancy effect, the mixed convective flow sheds vortex behind the cylinders and keeps periodic oscillating. The variations of characteristic quantities related to flow and heat transfer processes, such as the overall drag and lift coefficients and the Nusselt numbers, are presented and discussed. Furthermore, the influence of thermal buoyancy on the fluid flow and heat transfer are discussed and analysed. © 2013 Elsevier Ltd. All rights reserved.

  6. Stratified two-phase flow pattern modulation in a horizontal tube by the mesh pore cylinder surface

    International Nuclear Information System (INIS)

    Highlights: ► A phase separation concept was proposed to modulate flow pattern in a tube. ► The cross section of the tube is divided into an annular region and an inner region. ► Stratified flow pattern was successfully modulated. ► Liquid can be within the mesh pore cylinder with gas contacting with the tube wall surface. ► The idea was expected to enhance the condensation heat transfer. - Abstract: Condensation heat transfer has been studied in the past century due to its wide applications in energy and power systems. The key scientific issue is the thick liquid thickness near the tube wall along the condenser tube length. The fabricated microstructures on the inner wall are the conventional technique to improve the performance. Here a passive phase separation concept was proposed to create distinct phase distribution. An empty cylinder made of a single layer of mesh pore surface was suspended in a tube, dividing the tube into an annular region and an inner region. The mesh pore surface prevents gas phase entering the inner region but sucks liquid towards the inner region. Thus largest possibility for gas directly contacted with the inner wall surface is ensured. An air/water two-phase flow experiment was performed and the stratified flow pattern modulation was investigated. When the liquid level in the horizontal tube is relatively higher, the liquid can be thoroughly within the mesh cylinder to form the “gas-floating-liquid” mode. The whole inner tube wall surface is covered by the gas phase. If the liquid content is relatively smaller, partial liquid can be sucked into the mesh cylinder. The contact area between the inner tube wall and gas is increased. The stratified flow pattern modulation is expected to significantly enhance the condensation heat transfer under low mass fluxes which is being verified by our continuous experiment

  7. Film condensation of steam flowing downward on a tier of horizontal cylinders at different inclination angles in the presence of a non-condensable gas

    Science.gov (United States)

    Ramadan, Abdulghani; Yamali, Cemil

    2013-12-01

    The problem of forced laminar film condensation of steam flowing downward a tier of horizontal cylinders is investigated numerically. The effects of free stream non-condensable gas, air concentration (m1,∞), free stream velocity (Reynolds number), cylinder diameter, and angle of inclination on the condensation heat transfer are analyzed. Two flow arrangements, inline and staggered, are analyzed and investigated. The mathematical model takes into account the effect of staggering of the cylinders and how condensation is affected at the lower cylinders when condensate does not fall on to the center line of the cylinders. Condensation heat transfer results are available in ranges from (U∞ = 1 - 30 m/s) for free stream velocity, (m1,∞ = 0.01 -0.8) for free stream air mass fraction and (D = 12.7 -50.8 mm) for cylinder diameter. Results show that; a remarked reduction in the vapor side heat transfer coefficient is noticed. This results from the presence of small amounts of free stream air mass fractions in the steam-air mixture and increase in the cylinder diameter. On the other hand, it increases by increasing the free stream velocity (Reynolds number). Average heat transfer coefficient at the middle and the bottom cylinders increases by increasing the angle of inclination, whereas, no significant change is observed for that of the upper cylinder. Down the bank, a rapid decrease in the vapor side heat transfer coefficient is noticed. It may be resulted from the combined effects of inundation, decrease in the vapor velocity and increase in the non-condensable gas (air) at the bottom cylinders in the bank.

  8. Mixed convection flow from a horizontal circular cylinder embedded in a porous medium filled by a nano-fluid: Buongiorno-Darcy model

    International Nuclear Information System (INIS)

    Steady mixed convection boundary layer flow from an isothermal horizontal circular cylinder embedded in a porous medium filled with a nano-fluid has been studied for both cases of a heated and cooled cylinder using the Buongiorno-Darcy mathematical nano-fluid model. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme. The solutions for the flow and heat transfer characteristics are evaluated numerically for various values of the governing parameters, namely the constant mixed convection parameter λ, the traditional Lewis number Le, the buoyancy ratio parameter Nr, the Brownian motion parameter Nb and the thermophoresis parameter Nt. It is found that in the present case of the porous medium flow, the separation is always suppressed at negative values of λ. When λ changes from -2.1 to 0, one has a 'heating' of the cylinder, but a heating in the negative range of λ (λ 0) delays the separation of the boundary layer and if the cylinder is hot enough (large values of λ > 0), then it is suppressed completely at a positive value of λ, somewhere between 0.88 and 0.89. On the other hand, cooling the cylinder (λ < 0) brings the boundary layer separation point nearer to the lower stagnation point and for a sufficiently cold cylinder (large values of λ < 0) there will not be a boundary layer on the cylinder. (authors)

  9. Study of film boiling heat transfer from a sphere and a horizontal cylinder embedded in a liquid saturated porous medium

    International Nuclear Information System (INIS)

    This paper analyses both theoretically and experimentally the problem of film boiling from a body embedded in a liquid saturated porous medium. Two body geometries are investigated thoroughly: a horizontal cylinder and a sphere. The theoretical model relies on the Brinkman-extended flow model to describe the flow field inside the thin vapor layer occupying the neighborhood near the heated surface. The theoretical model also includes an improved formulation of the effective conductivity in the vicinity of the heater as a function of the vapor layer thickness and the geometry of the porous medium material. Solutions are obtained for the vapor layer thickness and the local Nusselt number as a function of angular position. Numerical solutions are also obtained for the overall heat transfer rates from the heated surface to the fluid for a range of problem parameters. Experimental data for a 12.70 mm OD stainless steel cylindrical heater embedded in a 3-mm glass particles porous medium were obtained under steady state operation. The experimental data obtained are compared with the theoretical analysis. The comparison shows that there is a good agreement between theory and experiments. The theoretical model is also compared with the experimental data obtained by other investigators for a spherical geometry. Excellent results are obtained in such comparison

  10. Forced Convection Film Boiling Heat Transfer from a Horizontal Cylinder to Liquid Cross-flowing Upward : 1st Report, Saturated Liquid

    OpenAIRE

    Ito, Takehiro; Nishikawa, Kaneyasu; Shigechi, Tooru

    1981-01-01

    Forced convection film boiling heat transfer from a horizontal cylinder to saturated liquid cross-flowing upward is analyzed based on the two-phase boundary-layer theory. Numerical solution of the conservation equations is determined by means of the integral method of boundary-layer for water, ethanol and hexane under the atmospheric pressure. The velocity profile, separation point of the boundary-layer, thickness of the boundary-layer, distribution of the heat transfer coefficients and avera...

  11. Forced Convection Film Boiling Heat Transfer from a Horizontal Cylinder to Liquid Cross-flowing Upward : 2nd Report, Subcooled Liquid

    OpenAIRE

    Shigechi, Tooru; Ito, Takehiro; Nishikawa, Kaneyasu

    1983-01-01

    Forced convection film boiling heat transfer from a horizontal cylinder to a subcooled liquid cross-flowing upward is analysed based on the two-phase boundary-layer theory. Numerical solution of the conservation equations is determined for subcooled water, ethanol and hexane under the atmospheric pressure by the method similar to that of the first report for saturated liquid. The velocity profile, the separation point in the vapor film, the thickness of the boundary-layer and the average Nuss...

  12. Radiation Effect on Mixed Convection Boundary Layer Flow of a Viscoelastic Fluid over a Horizontal Circular Cylinder with Constant Heat Flux

    OpenAIRE

    Hussain Ahmad; Tariq Javed; Abuzar Ghaffari

    2016-01-01

    In the present article, radiation effect on mixed convection boundary layer flow of a viscoelastic fluid over a horizontal circular cylinder with constant heat flux has been numerically analyzed. The governing boundary layer equations are transformed to dimensionless nonlinear partial differential equations. The equations are solved numerically by using Keller-box method. The computed results are in excellent agreement with the previous studies. Skin friction coefficient and Nusselt number ar...

  13. Horizontal

    Institute of Scientific and Technical Information of China (English)

    ZHONG; Chunping

    2005-01-01

    [1]Wu, H., Bochner technique in differential geometry, Advance in Math. (in Chinese), 1981, 10(1): 57-76.[2]Morrow, J., Kodaira, K., Complex Manifolds, New York: Holt, Rinehart & Winston, 1971.[3]Abate, M., Aikou, T., Patrizio, G., Preface for Complex Finsler Geometry, Cont. Math., Vol. 196, Providence,RI: Amer. Math. Soc., 1996, 97-100.[4]Abate, M., Patrizio, G., Finsler Metrics-A global approach with applications to geometric function theory,Lecture Notes in Mathematics, Vol. 1591, Bedin: Springer-Verlag, 1994.[5]Antonelli, P. L., Lackey, B.(eds.), The Theory of Finslerian Laplacians and Applications, MAIA 459, Dordrecht:Kluwer Academic Publishers, 1998.[6]Bao, D., Lackey, B., A Hodge decomposition theorem for Finsler spaces, C. R. Acad. Sci. Paris, t. 323, Serie 1,1996, 51-56.[7]Munteanu, O., Weitzenbock formulas for horizontal and vertical Laplacians, Houston Journal of Mathematics,2003, 29(4): 889-900.[8]Faran, J. J., The equivalence problem for complex Finsler Hamiltonians, Cont. Math.,Vol. 196, Providence, RI:Amer. Math. Soc., 1996, 133-144.[9]Kobayashi, S., Complex Finsler vector bundles, Cont. Math., Vol. 196, Providence, RI: Amer. Math. Soc.,1996,145-153.[10]Aikou, T., On complex Finsler manifolds, Rep. Fac. Sci. Kagoshima Univ. (Math. Phys. & Chem.), 1991, 24:9-25.

  14. Numerical analysis of the effect of radiation on laminar steady natural convection in a two-dimensional participating medium between two horizontal confocal elliptical cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Borjini, M.N.; Mbow, C.; Daguenet, M. [Univ. de Perpignan (France). Lab. de Thermodynanique et Energetique

    1999-04-01

    Over the last two decades, natural convection in horizontal annular spaces has been studied extensively because of its numerous industrial applications, namely, nuclear reactor design, cooling of electronic equipment, study of pressurized-gas underground electric transmission cables, and solar systems. Compound parabolic collectors involve convection heat transfer in the space between the receive envelope and the surface formed by the cover and the reflector. Here, combined radiation and natural convection in a participating medium between two horizontal confocal elliptical cylinders is investigated numerically. The equations of steady, laminar two-dimensional natural convection are written by using an elliptic-cylinder coordinates system, the stream function, and the vorticity. The finite volume radiation solution method and the control volume technique are used to discretize the coupled equations of momentum, energy, and radiative transfer. Numerical solutions are obtained for Rayleigh numbers in the range 10{sup 4} to 2 {times} 10{sup 5} and the radiation-conduction parameter ranging from 0 to {infinity}. The special case corresponding to the convective flow within the annulus formed by an elliptical cylinder surrounding a flat plate is also considered.

  15. Effect of surface conditions on transient critical heat fluxes for a horizontal cylinder in a pool of water at pressures due to exponentially increasing heat inputs

    International Nuclear Information System (INIS)

    The transient critical heat fluxes, CHFs, on 1.2-mm horizontal cylinders with mirror finished surface (MS) and Emery-3 finished rough one (RS) in a pool of water due to exponentially increasing heat inputs, Q0et/τ, with the periods, τ, ranged from 20 s down to 2 ms at pressures ranging from atmospheric up to 2 MPa for the subcoolings ranging from 0 to 80 K were measured. A heat input with the period of 20 s corresponds to quasi-steadily increasing one. The obtained data compared with the corresponding data for a cylinder with commercial surface (CS) which were already published in other papers. The trend of CHFs for the periods was generally as follows: the CHF first increases with a decrease in period up to a certain maximum CHF, then it decreases down to a minimum CHF and finally again increases with a decrease in period; namely the CHFs for the periods are separated into the first, second and third groups for longer, shorter and intermediate periods, respectively. The three groups of the CHFs for the periods tested were clearly observed for the cylinders with MS and RS, though the CHFs values for the shorter periods belonging to the second group were not observed for the cylinder with CS except those for the saturation condition at around atmospheric pressure, and those for high subcoolings at higher pressures. At the CHFs belonging to the second group the direct or semi-direct transition clearly occurs from transient conduction regime to film boiling without or with the vapor bubbles for a while with instantaneous increasing of heat flux for both cylinders of MS and RS. It was assumed that the transitions at the CHFs occur due to the explosive-like heterogeneous spontaneous nucleation (HSN) in originally flooded cavities similar to the assumption for the cylinder with CS previously published. It should be noted that as a typical example the minimum CHFs for the periods of 10 ms on the MS and RS cylinders at the pressure of 1 MPa for the subcooling of 40 K

  16. Buoyancy and blockage effects on transient laminar opposing mixed convection heat transfer from two horizontal confined isothermal cylinder in tandem

    Science.gov (United States)

    Martínez-Suástegui, Lorenzo; Salcedo, Erick; Cajas, Juan; Treviño, César

    2015-11-01

    Transient mixed convection in a laminar cross-flow from two isothermal cylinders in tandem arrangement confined inside a vertical channel is studied numerically using the vorticity-stream function formulation of the unsteady two-dimensional Navier-Stokes and energy equations. Numerical experiments are performed for a Reynolds number based on cylinder diameter of Re = 200, Prandtl number of Pr = 7, blockage ratio of D/H = 0.2, a pitch-to-diameter ratio of L/D = 2, and several values of buoyancy strength or Richardson number Ri = Gr/Re2. The results reported herein demonstrate how the wall confinement, interference effects and opposing buoyancy affect the flow structure and heat transfer characteristics of the cylinder array. This research was supported by the Consejo Nacional de Ciencia y Tecnología (CONACYT), Grant number 167474 and by the Secretaría de Investigación y Posgrado del IPN, Grant number SIP 20141309.

  17. Effect of surface conditions on transient critical heat fluxes for a horizontal cylinder in a pool of water at pressures due to exponentially increasing heat inputs

    International Nuclear Information System (INIS)

    The transient critical heat fluxes, CHFs, on 1.2mm horizontal cylinders with mirror finished and Emery-3 finished rough surfaces(MS, RS) in a pool of water due to exponentially increasing heat inputs, Qoet/τ, with the periods, τ, ranged from 20s down to 2ms at the pressures ranging from atmospheric up to about 2MPa for the subcoolings ranging from zero up to 80K were measured: the heat input with the period of 20s corresponds to quasi-steadily increasing one. The data compared with the corresponding data for the cylinder with commercial surface(CS). The trend of CHFs for the periods was generally as follows: the CHF first increases with the decrease in period up to a certain maximum CHF, then it decreases down to a minimum CHF and again increases with the decrease in period; namely the CHFs for the periods are separated into the 1st, 2nd and 3rd groups for longer, shorter and intermediate periods respectively. The three groups of the CHFs were clearly observed for the cylinders with MS and RS though the CHFs values for the shorter periods were not observed for the cylinder with CS except those for the saturation condition at around atmospheric pressure, and those for high subcoolings at higher pressures. At the CHFs belonging to the 2nd group the direct or semi-direct transition clearly occurs from transient conduction regime to film boiling without or with the vapor bubbles for a while with instantaneous increasing of heat flux for both cylinders of MS and RS; at the CHFs the transitions occur due to the explosive-like heterogeneous spontaneous nucleation in originally flooded cavities. It should be noted that as a typical example the minimum CHFs for the periods of 10ms on the MS and RS cylinders at the pressure of 1MPa for the subcooling of 40K were about 40% of the corresponding steady-state CHF. It was observed that the trend of CHFs for the 2nd and 3rd groups are significantly affected by the cylinder surface conditions. (J.P.N.)

  18. Flow and heat transfer characteristics of falling water film on horizontal circular and non-circular cylinders

    Institute of Scientific and Technical Information of China (English)

    LUO Lin-cong; ZHANG Guan-min; PAN Ji-hong; TIAN Mao-cheng

    2013-01-01

    This paper presents a two-dimensional CFD study of the falling film evaporation of horizontal tubes with different shapes applied in the seawater desalination.The flow and heat transfer characteristics of the falling water film on one circular tube and two non-circular shaped tubes,a drop-shaped tube and an oval-shaped tube,are analyzed,respectively.The Volume Of Fluid (VOF)method is employed to investigate the influence of the mass flow rate and the feeder height on the distribution of the film thickness and the heat transfer performance.The numerical results show that the minimum value of the film thickness appears approximately at the angular positions of 125°,160° and 170° for the smooth circular,oval-and drop-shaped tubes,respectively.The film thickness grows with the increase of the mass flow rate and the decrease of the feeder height,while the variation pattern varies for different tubes.Moreover,compared with the circular tube,the drop-and oval-shaped tubes have a lower dimensionless temperature and a thinner thermal boundary layer,which means a better heat transfer performance.Finally,the numerical results correlate well with the experimental and predicted data in literature.

  19. Radiation Effect on Mixed Convection Boundary Layer Flow of a Viscoelastic Fluid over a Horizontal Circular Cylinder with Constant Heat Flux

    Directory of Open Access Journals (Sweden)

    Hussain Ahmad

    2016-01-01

    Full Text Available In the present article, radiation effect on mixed convection boundary layer flow of a viscoelastic fluid over a horizontal circular cylinder with constant heat flux has been numerically analyzed. The governing boundary layer equations are transformed to dimensionless nonlinear partial differential equations. The equations are solved numerically by using Keller-box method. The computed results are in excellent agreement with the previous studies. Skin friction coefficient and Nusselt number are emphasized specifically. These quantities are displayed against the curvature parameter. The effects of pertinent parameters involved in the problem namely effective Prandtl number and mixed convection parameter on skin friction coefficient and Nusselt number are shown through graphs and table. Boundary layer separation points are also calculated with and without radiation and a comparison is shown. The presence of radiation helps to decrease or increase the skin friction coefficient for the negative or positive values of the mixed convection parameter accordingly. The decrease in value of effective Prandtl number helps to increase the value of skin friction coefficient and Nusselt number for viscoelastic fluids.

  20. Dropwise Condensation on Hydrophobic Cylinders

    CERN Document Server

    Park, Kyoo-Chul; Hoang, Michelle; McManus, Brendan; Aizenberg, Joanna

    2016-01-01

    In this work, we studied the effect of the diameter of horizontal hydrophobic cylinders on droplet growth. We postulate that the concentration gradient created by natural convection around a horizontal circular cylinder is related to the droplet growth on the cylinder by condensation. We derive a simple scaling law of droplet growth and compare it with experimental results. The predicted negative exponent of drop diameter (d) as a function of cylinder diameter (D) at different time points is similar to the general trend of experimental data. Further, this effect of cylinder diameter on droplet growth is observed to be stronger than the supersaturation conditions created by different surface temperatures.

  1. Biological mechanisms associated with triazophos (TAP) removal by horizontal subsurface flow constructed wetlands (HSFCW).

    Science.gov (United States)

    Wu, Juan; Feng, Yuqin; Dai, Yanran; Cui, Naxin; Anderson, Bruce; Cheng, Shuiping

    2016-05-15

    Triazophos (TAP) is a widely used pesticide that is easily accumulated in the environment due to its relatively high stability: this accumulation from agricultural runoff results in potential hazards to aquatic ecosystems. Constructed wetlands are generally considered to be an effective technology for treating TAP polluted surface water. However, knowledge about the biological mechanisms of TAP removal is still lacking. This study investigates the responses of a wetland plant (Canna indica), substrate enzymes and microbial communities in bench-scale horizontal subsurface-flow constructed wetlands (HSCWs) loaded with different TAP concentrations (0, 0.1, 0.5 and 5 mg · L(-1)). The results indicate that TAP stimulated the activities of superoxide dismutase (SOD) and peroxidase (POD) in the roots of C. indica. The highest TAP concentrations significantly inhibited photosynthetic activities, as shown by a reduced effective quantum yield of PS II (ΦPS II) and lower electron transport rates (ETR). However, interestingly, the lower TAP loadings exhibited some favorable effects on these two variables, suggesting that C. indica is a suitable species for use in wetlands designed for treatment of low TAP concentrations. Urease and alkaline phosphatase (ALP) in the wetland substrate were activated by TAP. Two-way ANOVA demonstrated that urease activity was influenced by both the TAP concentrations and season, while acidphosphatase (ACP) only responded to seasonal variations. Analysis of high throughput sequencing of 16S rRNA revealed seasonal variations in the microbial community structure of the wetland substrate at the phylum and family levels. In addition, urease activity had a greater correlation with the relative abundance of some functional microbial groups, such as the Bacillaceae family, and the ALP and ACP may be influenced by the plant more than substrate microbial communities. PMID:26897579

  2. Horizontal Gene Transfer among Bacteria and Its Role in Biological Evolution

    OpenAIRE

    Werner Arber

    2014-01-01

    This is a contribution to the history of scientific advance in the past 70 years concerning the identification of genetic information, its molecular structure, the identification of its functions and the molecular mechanisms of its evolution. Particular attention is thereby given to horizontal gene transfer among microorganisms, as well as to biosafety considerations with regard to beneficial applications of acquired scientific knowledge.

  3. Numerical analysis of the effect of radiation on steady laminar natural convection in two-dimensional participating medium between horizontal concentric or vertically eccentric cylinders; Etude numerique de l'influence du transfert radiatif sur la convection naturelle laminaire, bidimensionnelle, permanente, dans un espace annulaire d'axe horizontal, delimite par deux cylindres circulaires isothermes

    Energy Technology Data Exchange (ETDEWEB)

    Naceur Borjini, M.; Mbow, Ch.; Daguenet, M. [Universite de Perpignan, 66 (France). Laboratoire de Thermodynamique et Energetique

    1998-06-01

    Combined radiation and natural convection in a participating medium between concentric or vertically eccentric horizontal cylinders is investigated numerically. The annular medium is considered as a gray, emitting, absorbing, and isotropically scattering gas. The equations of steady, laminar, two-dimensional, thermal, natural convection are written by using a two-cylindrical coordinate system, the stream function, and the vorticity. The finite volumes method is used to discretize the coupled equations of momentum, energy, and radiative transfer. To solve the global nonlinear algebraic equations the successive-over-relaxation iterating scheme is applied. Numerical solutions are obtained for a Rayleigh number in the range 10{sup 3}-10{sup 5} and radiation-conduction parameter ranging from 0 to {infinity}. The influences of radiation-conduction parameter, Rayleigh number and other parameters on flow and temperature distributions and heat transfer are discussed. (authors)

  4. Inner cylinder of the CMS vacuum tank.

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    The vacuum tank of the CMS magnet system consists of inner and outer stainless-steel cylinders and houses the superconducting coil. The inner cylinder contains all the barrel sub-detectors, which it supports via a system of horizontal rails. The cylinder is pictured here in the vertical position on a yellow platform mounted on the ferris-wheel support structure. This will allow it to be pivoted and inserted into the outer cylinder already attached to the innermost ring of the barrel yoke.

  5. Inner and outer cylinders of the CMS vacuum tank.

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    The vacuum tank of the CMS magnet system consists of inner and outer stainless-steel cylinders and houses the superconducting coil. The inner cylinder contains all the barrel sub-detectors, which it supports via a system of horizontal rails. The cylinder is pictured here in the vertical position on a yellow platform mounted on the ferris-wheel support structure. This will allow it to be pivoted and inserted into the already installed outer cylinder, through which this photo was taken.

  6. Flow-induced vibrations of two tandem cylinders in a channel

    OpenAIRE

    Jiang Ren-Jie

    2012-01-01

    We numerically studied flow-induced vibrations of two tandem cylinders in transverse direction between two parallel walls. The effect of the horizontal separation between two cylinders, ranging from 1.1 to 10, on the motions of the cylinders and the flow structures were investigated and a variety of periodic and non-periodic vibration regimes were observed. The results show that when two cylinders are placed in close proximity to each other, compared with the case of an isolated cylinde...

  7. Investigation of breached depleted UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    DeVan, J.H. [Martin Marietta Energy Systems, Inc., Oak Ridge, TN (United States)

    1991-12-31

    In June 1990, during a three-site inspection of cylinders being used for long-term storage of solid depleted UF{sub 6}, two 14-ton cylinders at Portsmouth, Ohio, were discovered with holes in the barrel section of the cylinders. An investigation team was immediately formed to determine the cause of the failures and their impact on future storage procedures and to recommend corrective actions. Subsequent investigation showed that the failures most probably resulted from mechanical damage that occurred at the time that the cylinders had been placed in the storage yard. In both cylinders evidence pointed to the impact of a lifting lug of an adjacent cylinder near the front stiffening ring, where deflection of the cylinder could occur only by tearing the cylinder. The impacts appear to have punctured the cylinders and thereby set up corrosion processes that greatly extended the openings in the wall and obliterated the original crack. Fortunately, the reaction products formed by this process were relatively protective and prevented any large-scale loss of uranium. The main factors that precipitated the failures were inadequate spacing between cylinders and deviations in the orientations of lifting lugs from their intended horizontal position. After reviewing the causes and effects of the failures, the team`s principal recommendation for remedial action concerned improved cylinder handling and inspection procedures. Design modifications and supplementary mechanical tests were also recommended to improve the cylinder containment integrity during the stacking operation.

  8. Swirling flows in horizontally vibrated beds of dense granular materials

    Institute of Scientific and Technical Information of China (English)

    Ali Bakhshinejad; Piroz Zamankhan

    2012-01-01

    In a series of experiments,a granular material in a rectangular container with two hollow cylinders was studied as it underwent horizontal vibrations.At the peak values of acceleration,novel swirling granular flows were observed in the cylinders while the grains cascaded down the outer surface of the piles that formed outside the cylinders.Computer simulations were performed that supported our interpretation of the behaviour observed in the experiments.

  9. [Fe2L3]4+ Cylinders Derived from Bis(bidentate 2-Pyridyl-1,2,3-triazole “Click” Ligands: Synthesis, Structures and Exploration of Biological Activity

    Directory of Open Access Journals (Sweden)

    James D. Crowley

    2013-05-01

    Full Text Available A series of metallosupramolecular [Fe2L3](BF44 “click” cylinders have been synthesized in excellent yields (90%–95% from [Fe(H2O6](BF42 and bis(bidentate pyridyl-1,2,3-triazole ligands. All complexes were characterized by elemental analysis, IR, UV-vis, 1H-, 13C- and DOSY-NMR spectroscopies and, in four cases, the structures confirmed by X-ray crystallography. Molecular modeling indicated that some of these “click” complexes were of similar size and shape to related biologically active pyridylimine-based iron(II helicates and suggested that the “click” complexes may bind both duplex and triplex DNA. Cell-based agarose diffusion assays showed that the metallosupramolecular [Fe2L3](BF44 “click” cylinders display no antifungal activity against S. cerevisiae. This observed lack of antifungal activity appears to be due to the poor stability of the “click” complexes in DMSO and biological media.

  10. Indirect interactions of membrane-adsorbed cylinders

    OpenAIRE

    Weikl, Thomas R.

    2003-01-01

    Biological and biomimetic membranes often contain aggregates of embedded or adsorbed macromolecules. In this article, the indirect interactions of cylindrical objects adhering to a planar membrane are considered theoretically. The adhesion of the cylinders causes a local perturbation of the equilibrium membrane shape, which leads to membrane-mediated interactions. For a planar membrane under lateral tension, the interaction is repulsive for a pair of cylinders adhering to the same side of the...

  11. Cylinder monitoring program

    Energy Technology Data Exchange (ETDEWEB)

    Alderson, J.H. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    Cylinders containing depleted uranium hexafluoride (UF{sub 6}) in storage at the Department of Energy (DOE) gaseous diffusion plants, managed by Martin Marietta Energy Systems, Inc., are being evaluated to determine their expected storage life. Cylinders evaluated recently have been in storage service for 30 to 40 years. In the present environment, the remaining life for these storage cylinders is estimated to be 30 years or greater. The group of cylinders involved in recent tests will continue to be monitored on a periodic basis, and other storage cylinders will be observed as on a statistical sample population. The program has been extended to all types of large capacity UF{sub 6} cylinders.

  12. Delamination of Composite Cylinders

    Science.gov (United States)

    Davies, Peter; Carlsson, Leif A.

    The delamination resistance of filament wound glass/epoxy cylinders has been characterized for a range of winding angles and fracture mode ratios using beam fracture specimens. The results reveal that the delamination fracture resistance increases with increasing winding angle and mode II (shear) fraction (GΠ/G). It was also found that interlaced fiber bundles in the filament wound cylinder wall acted as effective crack arresters in mode I loading. To examine the sensitivity of delamina-tion damage on the strength of the cylinders, external pressure tests were performed on filament-wound glass/epoxy composite cylinders with artificial defects and impact damage. The results revealed that the cylinder strength was insensitive to the presence of single delaminations but impact damage caused reductions in failure pressure. The insensitivity of the failure pressure to a single delamination is attributed to the absence of buckling of the delaminated sublaminates before the cylinder wall collapsed. The impacted cylinders contained multiple delaminations, which caused local reduction in the compressive load capability and reduction in failure pressure. The response of glass/epoxy cylinders was compared to impacted carbon reinforced cylinders. Carbon/epoxy is more sensitive to damage but retains higher implosion resistance while carbon/PEEK shows the opposite trend.

  13. Approximation by Cylinder Surfaces

    DEFF Research Database (Denmark)

    Randrup, Thomas

    1997-01-01

    We present a new method for approximation of a given surface by a cylinder surface. It is a constructive geometric method, leading to a monorail representation of the cylinder surface. By use of a weighted Gaussian image of the given surface, we determine a projection plane. In the orthogonal...... projection of the surface onto this plane, a reference curve is determined by use of methods for thinning of binary images. Finally, the cylinder surface is constructed as follows: the directrix of the cylinder surface is determined by a least squares method minimizing the distance to the points in the...

  14. A Sequence of Cylinders

    Science.gov (United States)

    Johnson, Erica

    2006-01-01

    Hoping to develop in her students an understanding of mathematics as a way of thinking more than a way of doing, the author of this article describes how her students worked on a spatial reasoning problem stemming from an iteratively constructed sequence of cylinders. She presents an activity of making cylinders out of paper models, and for every…

  15. Tandem Cylinder Noise Predictions

    Science.gov (United States)

    Lockhard, David P.; Khorrami, Mehdi R.; CHoudhari, Meelan M.; Hutcheson, Florence V.; Brooks, Thomas F.; Stead, Daniel J.

    2007-01-01

    In an effort to better understand landing-gear noise sources, we have been examining a simplified configuration that still maintains some of the salient features of landing-gear flow fields. In particular, tandem cylinders have been studied because they model a variety of component level interactions. The present effort is directed at the case of two identical cylinders spatially separated in the streamwise direction by 3.7 diameters. Experimental measurements from the Basic Aerodynamic Research Tunnel (BART) and Quiet Flow Facility (QFF) at NASA Langley Research Center (LaRC) have provided steady surface pressures, detailed off-surface measurements of the flow field using Particle Image Velocimetry (PIV), hot-wire measurements in the wake of the rear cylinder, unsteady surface pressure data, and the radiated noise. The experiments were conducted at a Reynolds number of 166 105 based on the cylinder diameter. A trip was used on the upstream cylinder to insure a fully turbulent shedding process and simulate the effects of a high Reynolds number flow. The parallel computational effort uses the three-dimensional Navier-Stokes solver CFL3D with a hybrid, zonal turbulence model that turns off the turbulence production term everywhere except in a narrow ring surrounding solid surfaces. The current calculations further explore the influence of the grid resolution and spanwise extent on the flow and associated radiated noise. Extensive comparisons with the experimental data are used to assess the ability of the computations to simulate the details of the flow. The results show that the pressure fluctuations on the upstream cylinder, caused by vortex shedding, are smaller than those generated on the downstream cylinder by wake interaction. Consequently, the downstream cylinder dominates the noise radiation, producing an overall directivity pattern that is similar to that of an isolated cylinder. Only calculations based on the full length of the model span were able to

  16. Antennas on circular cylinders

    DEFF Research Database (Denmark)

    Knudsen, H. L.

    1959-01-01

    antenna in a circular cylinder. By a procedure similar to the one used by Silver and Saunders, expressions have been derived for the field radiated from an arbitrary surface current distribution on a cylinder surface coaxial with a perfectly conducting cylinder. The cases where the space between the two...... cylindrical surfaces have the sane characteristic constants and different constants are treated separately. Extensive numerical computations of the field radiated from the slot antennas described here are being carried out, but no numerical results are yet available...

  17. Oscillations and translation of a free cylinder in a confined flow

    OpenAIRE

    D'Angelo, Maria Veronica; Hulin, Jean-Pierre; Auradou, Harold

    2013-01-01

    An oscillatory instability has been observed experimentally on an horizontal cylinder free to move and rotate between two parallel vertical walls of distance H; its characteristics differ both from vortex shedding driven oscillations and from those of tethered cylinders in the same geometry. The vertical motion of the cylinder, its rotation about its axis and its transverse motion across the gap have been investigated as a function of its diameter D, its density s, of the mean vertical veloci...

  18. Drag and lift forces on a counter-rotating cylinder in rotating flow

    NARCIS (Netherlands)

    Sun, Chao; Mullin, Tom; Wijngaarden, van Leen; Lohse, Detlef

    2010-01-01

    Results are reported of an experimental investigation into the motion of a heavy cylinder free to move inside a water-filled drum rotating around its horizontal axis. The cylinder is observed to either co-rotate or, counter-intuitively, counter-rotate with respect to the rotating drum. The flow was

  19. Stress analysis of cylinder to cylinder intersections

    International Nuclear Information System (INIS)

    Cylinder to cylinder intersections have numerous applications in the power industry from different piping junctions to pressure vessel nozzles. A specific purpose computer program has been installed at the author's establishment for finite element analysis of such geometries. Some of the experiences are presented giving a short overview of the analysis of unreinforced man-holes, demonstrating how a more economical design has been verified by analysis. The program installed has linear-elastic and elasto-plastic capabilities. Further, it is prepared for heat transfer analysis with subsequent thermal stress computation. An efficient pre- and post-processor has also been installed and enhanced by the author. The software used is at its present stage capable for problem definition with input data such as outside/ inside diameters, length and number of subdivisions. Similarly simple is the load definition and the graphic representation of the full output. (author)

  20. Ocorrência e biologia do Rhodnius neglectus Lent, 1954 em macaubeiras da periferia de Belo Horizonte, Minas Gerais Occurence and biology of Rhodnius neglectus Lent, 1954 in palm tress of suburban areas of Belo Horizonte, Minas Gerais

    Directory of Open Access Journals (Sweden)

    Liléia Diotaiuti

    1984-09-01

    Full Text Available Oitenta e uma macaubeiras (A. sclerocarpa foram derrubadas e dissecadas na periferia de Belo Horizonte, no período de abril/ 1979 a julho/1980. Foram capturados 463 exemplares de Rhodnius neglectus, com uma taxa de infestação das palmeiras de 60,5% e uma média de 9,45% triatomineos/palmeira positiva. O R. neglectus nesta região parece apresentar uma unica geração anual, com possibilidade de duas, sendo que o periodo de oviposição se relaciona com os meses quentes do ano, coincidindo com a predominância de formas jovens sobre os adultos. A observação sugere que a densidade populacional do R. neglectus no seu ecotopo natural possa estar relacionada com a disponibilidade de alimento e com a presença de predadores como o Telenomus sp., formigas, aranhas, hemipteros, escorpiões e pseudo-escorpiões. O indice global de infecção pelo Trypanosoma cruzi foi de 15,9%, indicando o R. neglectus como um importante vetor silvestre deste tripanosomatídeo cuja principal fonte e constituída por marsupiais. O R. neglectus na regiao encontra-se estreitamente associado a palmeira de macaúba, e as aves que as frequentam constituem sua principal fonte alimentar. As observações não sugerem o R.neglectus como uma espécie transmissora do T. cruzi ao homem nesta região.Eighty-one "macaubeiras" palm-trees (Acrocomia sclerocarpa from the periophery of Belo Horizonte city were cut down and dissected between April 1979 and July 1980. 60,5% of the trees were positive for R. neglectus and 463 specimens of this insect were collected, providing a mean rate of 9,45 individuals for positive palm-trees. R neglectus seems to present a single annual generation in this region, but evidence was obtained that two generations may occur. Its spawn period is related to the hot months of the year, when younger insects prevail over the adults. This observation suggests that higher population desities are related to better feeding conditions and to minor desities of

  1. Operation of nuclear steam turbine and thermal stress analysis of high pressure cylinder

    International Nuclear Information System (INIS)

    Operation mode of Nuclear steam turbine has direct influence on thermal stress of High Pressure (HP) Cylinder. The calculation results of HP cylinder thermal stress, horizontal joint contact stress, HP rotor thermal stress and fatigue life for 310 MW nuclear Steam turbine show that the HR cylinder thermal stress is not high and close attention should be paid to the seal of horizontal joint. It is recognized that the thermal stress and fatigue life of HP rotor become the limiting factors of turbine starting and load changing processes. Cold start and load rejection in particular can cause considerable loss of HP rotor life

  2. Is axial dispersion within rotating cylinders governed by the Froude number?

    Science.gov (United States)

    Third, J R; Müller, C R

    2012-12-01

    Axial dispersion rates of particles within horizontal rotating cylinders have been calculated for a decade of cylinder diameters. Throughout the range studied the rate of axial dispersion was found to be independent of the cylinder diameter. This phenomenon has been investigated further by spatially resolving the local contribution to the axial dispersion coefficient. This analysis demonstrates that, although the highest rates of axial dispersion occur at the free surface of the bed, there is a significant contribution to axial dispersion throughout the flowing region of the bed. Finally, based on an analogy with a Galton board, a linear relationship is proposed between the local rate of axial dispersion within a horizontal rotating cylinder and the product of the local particle concentration and the local shear rate in a plane perpendicular to the cylinder axis. PMID:23367939

  3. Rolling Cylinder Phase 1

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Taraborrelli, Valeria Taraborrelli

    Margheritini and Valeria Taraborrelli(valeria.taraborrelli@hotmail.it) with a total of 3 day visit from the developers. Laboratory tests in irregular waves will be performed by Lucia Margheritini. The report is aimed at the first stage testing of the Rolling Cylinder wave energy device. This phase includes...

  4. Equivariant harmonic cylinders

    OpenAIRE

    Burstall, F. E.; Kilian, M.

    2005-01-01

    We prove that a primitive harmonic map is equivariant if and only if it admits a holomorphic potential of degree one. We investigate when the equivariant harmonic map is periodic, and as an application discuss constant mean curvature cylinders with screw motion symmetries.

  5. 'Buffeting of single cylinders'

    International Nuclear Information System (INIS)

    The fluctuating lift and drag induced on a rigid cylinder immersed in a turbulent flow in the range of Reynolds numbers straddling the transition from subcritical to supercritical regime is examined. The buffeting forces are induced in response to turbulence generated by grids. In the present experiments, the integral scales of turbulence, l, for the grids used are less than the cylinder diameter (l/d < 1). Interpretation of these and other published data strongly suggest that the free stream disturbances (turbulence) affect the force response in two ways. In the absence of grid turbulence below a certain threshold level, it appears to simply modulate the spanwise spatial coherence of vortex shedding. In this situation, the spectral character retains the discrete or monochromatic Strouhal nature, while the RMS force levels decrease with increase in the measured free stream disturbance. On the other hand, the cylinder response to broad band excitation by the high intensity grid generated turbulence is no longer discrete although the spectral character still retains a 'humped' shape of a band pass filter. Centre band frequency of this band pass is very nearly, although not quite, the Strouhal frequency in the 'clean' flow. In any event, the RMS amplitudes continue to decline as the turbulent intensity is increased. While the evidence is suggestive, it is not as yet complete. The data on hand strongly suggest the domination of the cylinder buffeting phenomenon by the shed wake, at the lease for l/d < 1. A principle can also be extracted from the data. The persistence of the Strouhal frequency into the buffeting response spectrum suggests that the time scale so represented is inherent to flow/cylinder interactions even when the upstream flow is highly turbulent (and l/d < 1). (author)

  6. Diseño de actividades para la evaluación vertical y horizontal de competencias en los grados de Biología y Ciencias Ambientales

    OpenAIRE

    Rubio Valverde, Lourdes; Carmona Fernández, Raquel; Moreno Ostos, Enrique; Altamirano Jeschke, María; Fernández García, José Antonio

    2015-01-01

    En el presente trabajo se muestra el diseño de actividades para la evaluación de competencias en algunas asignaturas de los Grados de Biología y Ciencias Ambientales de la Universidad de Málaga. En concreto se han diseñado herramientas de evaluación transversales para determinar el grado de adquisición de competencias en asignaturas relacionadas verticalmente en el Grado de Biología y horizontalmente en el Grado de Ciencias Ambientales. El trabajo muestra un catálogo de competencias comunes e...

  7. Torsion of Noncircular Composite Cylinders

    Science.gov (United States)

    Rouse, Marshall; Hyer, Michael W.; Haynie, Waddy T.

    2005-01-01

    The paper presents a brief overview of the predicted deformation and failure characteristics of noncircular composite cylinders subjected to torsion. Using a numerical analysis, elliptical cylinders with a minor-to-major diameter ratio of 0.7 are considered. Counterpart circular cylinders with the same circumference as the elliptical cylinders are included for comparison. The cylinders are constructed of a medium-modulus graphite-epoxy material in a quasi-isotropic lay-up. Imperfections generated from the buckling mode shapes are included in the initial cross-sectional geometry of the cylinders. Deformations until first fiber failure, as predicted using the maximum stress failure criterion and a material degradation scheme, are presented. For increasing levels of torsion, the deformations of the elliptical cylinders, in the form of wrinkling of the cylinder wall, occur primarily in the flatter regions of the cross section. By comparison the wrinkling deformations of the circular cylinders are more uniformly distributed around the circumference. Differences in the initial failure and damage progression and the overall torque vs. twist relationship between the elliptical and circular cylinders are presented. Despite differences in the response as the cylinders are being loaded, at first fiber failure the torque and twist for the elliptical and circular cylinders nearly coincide.

  8. Poisson cylinders in hyperbolic space

    OpenAIRE

    Broman, Erik; Tykesson, Johan

    2015-01-01

    We consider the Poisson cylinder model in d-dimensional hyperbolic space. We show that in contrast to the Euclidean case, there is a phase transition in the connectivity of the collection of cylinders as the intensity parameter varies. We also show that for any non-trivial intensity, the diameter of the collection of cylinders is infinite.

  9. Biology of the subtropical sac-spawning euphausiid Nyctiphanes simplex in the northwestern seas of Mexico: Vertical and horizontal distribution patterns and seasonal variability of brood size

    Science.gov (United States)

    Gómez-Gutiérrez, Jaime; Tremblay, Nelly; Martínez-Gómez, Samuel; Robinson, Carlos J.; Del Ángel-Rodríguez, Jorge; Rodríguez-Jaramillo, Carmen; Zavala-Hernández, Christian

    2010-04-01

    Vertical and horizontal distributions of the subtropical euphausiid juvenile and adult Nyctiphanes simplex were mapped from samples collected during winter and summer 2007 in the Gulf of California, Mexico. During winter, wide-ranging high densities occurred in most of the Gulf of California. Densities decreased considerably during summer, with only at few locations having high densities. N. simplex made short daily vertical migrations of 50 m, clearly avoiding layers with temperatures >20 °C. In both seasons, N. simplex occurred above the low-oxygen layer (low-oxygen layer acts as the bottom limit of vertical distribution and horizontal distribution is limited at the southern part of the gulf to temperatures >23 °C. Seasonal brood size and reproductive effort were estimated for both sides of the Baja California Peninsula under ship board experiments as a proxy of the relative effect of seasonal environmental conditions for euphausiid reproduction. Experiments were done during March, July, and December 2004 at the entrance to Bahía Magdalena and its westward continental shelf and in November 2005 and January and July 2007 in the Gulf of California. Contrary to broadcast-spawning euphausiids, N. simplex, a sac-spawning euphausiid, has a significant association of the brood size as a function of the total length of females. N. simplex produces an average brood of 52 eggs female -1 (range 5-116 eggs female -1) with a estimated total fecundity of 936 eggs female -1 in a life span (360-1337 eggs female -1), of which about 8% of its carbon weight is released per spawn, significantly higher than estimates of previous studies. In Bahía Magdalena, broods contained more embryos in March and July 2004 than in December 2004 when temperatures increased to >23 °C. In the Gulf of California, broods had higher numbers of embryos in November and July than in January 2007, suggesting that N. simplex has an out-of-phase reproductive season on both coasts of the peninsula

  10. Rotating fermions inside a cylinder

    CERN Document Server

    Ambrus, Victor E

    2015-01-01

    We study rotating thermal states of a quantum fermion field inside a cylinder in Minkowski space-time. Two possible boundary conditions for the fermion field on the cylinder are considered: the spectral and MIT bag boundary conditions. If the radius of the cylinder is sufficiently small, rotating thermal expectation values are finite everywhere inside the cylinder. We also study the Casimir divergences on the boundary. The rotating thermal expectation values and the Casimir divergences have different properties depending on the boundary conditions applied at the cylinder. This is due to the local nature of the MIT bag boundary condition, while the spectral boundary condition is nonlocal.

  11. Anaesthesia gas supply: Gas cylinders

    Directory of Open Access Journals (Sweden)

    Uma Srivastava

    2013-01-01

    Full Text Available Invention of oxygen cylinder was one of the most important developments in the field of medical practice. Oxygen and other gases were compressed and stored at high pressure in seamless containers constructed from hand-forged steel in1880. Materials technology has continued to evolve and now medical gas cylinders are generally made of steel alloys or aluminum. The filling pressure as well as capacity has increased considerably while at the same time the weight of cylinders has reduced. Today oxygen cylinder of equivalent size holds a third more oxygen but weighs about 20 kg less. The cylinders are of varying sizes and are color coded. They are tested at regular intervals by the manufacturer using hydraulic, impact, and tensile tests. The top end of the cylinder is fitted with a valve with a variety of number and markings stamped on it. Common valve types include: Pin index valve, bull nose, hand wheel and integral valve. The type of valve varies with cylinder size. Small cylinders have a pin index valve while large have a bull nose type. Safety features in the cylinder are: Color coding, pin index, pressure relief device, Bodok seal, and label attached etc., Safety rules and guidelines must be followed during storage, installation and use of cylinders to ensure safety of patients, hospital personnel and the environment.

  12. Anaesthesia gas supply: gas cylinders.

    Science.gov (United States)

    Srivastava, Uma

    2013-09-01

    Invention of oxygen cylinder was one of the most important developments in the field of medical practice. Oxygen and other gases were compressed and stored at high pressure in seamless containers constructed from hand-forged steel in1880. Materials technology has continued to evolve and now medical gas cylinders are generally made of steel alloys or aluminum. The filling pressure as well as capacity has increased considerably while at the same time the weight of cylinders has reduced. Today oxygen cylinder of equivalent size holds a third more oxygen but weighs about 20 kg less. The cylinders are of varying sizes and are color coded. They are tested at regular intervals by the manufacturer using hydraulic, impact, and tensile tests. The top end of the cylinder is fitted with a valve with a variety of number and markings stamped on it. Common valve types include: Pin index valve, bull nose, hand wheel and integral valve. The type of valve varies with cylinder size. Small cylinders have a pin index valve while large have a bull nose type. Safety features in the cylinder are: Color coding, pin index, pressure relief device, Bodok seal, and label attached etc., Safety rules and guidelines must be followed during storage, installation and use of cylinders to ensure safety of patients, hospital personnel and the environment. PMID:24249883

  13. Anaesthesia Gas Supply: Gas Cylinders

    Science.gov (United States)

    Srivastava, Uma

    2013-01-01

    Invention of oxygen cylinder was one of the most important developments in the field of medical practice. Oxygen and other gases were compressed and stored at high pressure in seamless containers constructed from hand-forged steel in1880. Materials technology has continued to evolve and now medical gas cylinders are generally made of steel alloys or aluminum. The filling pressure as well as capacity has increased considerably while at the same time the weight of cylinders has reduced. Today oxygen cylinder of equivalent size holds a third more oxygen but weighs about 20 kg less. The cylinders are of varying sizes and are color coded. They are tested at regular intervals by the manufacturer using hydraulic, impact, and tensile tests. The top end of the cylinder is fitted with a valve with a variety of number and markings stamped on it. Common valve types include: Pin index valve, bull nose, hand wheel and integral valve. The type of valve varies with cylinder size. Small cylinders have a pin index valve while large have a bull nose type. Safety features in the cylinder are: Color coding, pin index, pressure relief device, Bodok seal, and label attached etc., Safety rules and guidelines must be followed during storage, installation and use of cylinders to ensure safety of patients, hospital personnel and the environment. PMID:24249883

  14. Numerical Simulation of Flow Interference Between Two Circular Cylinders

    Science.gov (United States)

    Gao, F.; Mingham, C. G.; Causon, D. M.

    2011-09-01

    Viscous flow past two circular cylinders in tandem and side-by-side arrangements is investigated numerically. The solution to the Navier-Stokes equations is obtained by means of a cell-centred finite volume method (FVM) based on a structured Cartesian grid with collocated variable arrangement. The pressure-velocity coupling is evaluated by using the SIMPLE algorithm. The 2D Cartesian cut cell mesh is generated on the horizontal plane, which is extended vertically to form the 3D grid. The simulations are based on the Reynolds number of 200, and the gap between the two cylinders are 1.5-3D for side-by-side arrangement and 3-4D for tandem. Instantaneous velocity contours of the flow around the cylinders and time histories of force coefficients are presented.

  15. Dynamic modeling and response of rigid embedded cylinders

    International Nuclear Information System (INIS)

    Following a brief review of the limitations of a popular technique for modeling the soil action in analyses of the dynamic response of deeply embedded cylindrical foundations and structures, the sources of the limitations are identified and a modification is proposed which, while retaining the attractiveness of the original model, defines correctly the action of the system. In the proposed approach, the soil medium is modeled by a series of elastically constrained, rather than unconstrained, thin horizontal layers with a circular hole at the center. The impedances of the constrained layers are established and are then used to evaluate the dynamic response of a rigid vertical cylinder embedded in a uniform viscoelastic stratum of constant thickness and infinite extent in the horizontal direction. The cylinder and the stratum are presumed to be supported on a non-deformable base undergoing a uniform horizontal motion. The effects of both harmonic and earthquake induced ground motions are considered. The response quantities examined include the dynamic force per unit of cylinder height and the corresponding base shear and base moment. The system investigated simulates the design of underground storage tanks at Hanford for the storage of radioactive wastes

  16. Approximation of Surfaces by Cylinders

    DEFF Research Database (Denmark)

    Randrup, Thomas

    1998-01-01

    We present a new method for approximation of a given surface by a cylinder surface. It is a constructive geometric method, leading to a monorail representation of the cylinder surface. By use of a weighted Gaussian image of the given surface, we determine a projection plane. In the orthogonal...... projection of the surface onto this plane, a reference curve is determined by use of methods for thinning of binary images. Finally, the cylinder surface is constructed as follows: the directrix of the cylinder surface is determined by a least squares method minimizing the distance to the points in the...

  17. Oscillatory and Steady Flows in the Annular Fluid Layer inside a Rotating Cylinder

    OpenAIRE

    Veronika Dyakova; Denis Polezhaev

    2016-01-01

    The dynamics of a low-viscosity fluid inside a rapidly rotating horizontal cylinder were experimentally studied. In the rotating frame, the force of gravity induces azimuthal fluid oscillations at a frequency equal to the velocity of the cylinder’s rotation. This flow is responsible for a series of phenomena, such as the onset of centrifugal instability in the Stokes layer and the growth of the relief at the interface between the fluid and the granular medium inside the rotating cylinder. The...

  18. Biologic

    CERN Document Server

    Kauffman, L H

    2002-01-01

    In this paper we explore the boundary between biology and the study of formal systems (logic). In the end, we arrive at a summary formalism, a chapter in "boundary mathematics" where there are not only containers but also extainers ><, entities open to interaction and distinguishing the space that they are not. The boundary algebra of containers and extainers is to biologic what boolean algebra is to classical logic. We show how this formalism encompasses significant parts of the logic of DNA replication, the Dirac formalism for quantum mechanics, formalisms for protein folding and the basic structure of the Temperley Lieb algebra at the foundations of topological invariants of knots and links.

  19. Horizontal Equity, Once More

    OpenAIRE

    Richard A. Musgrave

    1990-01-01

    Reconsiders the proposition that vertical equity is the primary norm for tax design, with horizontal equity a mere derivative therefrom. In the case of limited policy options, vertical and horizontal equity goals may conflict so that a trade-off will be needed. Independent values must then be assigned to each, confirming the standing of a horizontal as well as vertical equity as a primary norm.

  20. Horizontal gene transfer in plants.

    Science.gov (United States)

    Gao, Caihua; Ren, Xiaodong; Mason, Annaliese S; Liu, Honglei; Xiao, Meili; Li, Jiana; Fu, Donghui

    2014-03-01

    Horizontal gene transfer (HGT) describes the transmission of genetic material across species boundaries. HGT often occurs in microbic and eukaryotic genomes. However, the pathways by which HGTs occur in multicellular eukaryotes, especially in plants, are not well understood. We systematically summarized more than ten possible pathways for HGT. The intimate contact which frequently occurs in parasitism, symbiosis, pathogen, epiphyte, entophyte, and grafting interactions could promote HGTs between two species. Besides these direct transfer methods, genes can be exchanged with a vector as a bridge: possible vectors include pollen, fungi, bacteria, viruses, viroids, plasmids, transposons, and insects. HGT, especially when involving horizontal transfer of transposable elements, is recognized as a significant force propelling genomic variation and biological innovation, playing an important functional and evolutionary role in both eukaryotic and prokaryotic genomes. We proposed possible mechanisms by which HGTs can occur, which is useful in understanding the genetic information exchange among distant species or distant cellular components. PMID:24132513

  1. Fermionic Casimir interaction in cylinder-plate and cylinder-cylinder geometries

    CERN Document Server

    Teo, L P

    2015-01-01

    In this work, we consider the Casimir effect due to massless fermionic fields in the presence of long cylinders. More precisely, we consider the interaction between a cylinder parallel to a plate, between two parallel cylinders outside each other, and between a cylinder lying parallelly inside another cylinder. We derive the explicit formulas for the Casimir interaction energies and compute the leading and the next-to-leading order terms of the small separation asymptotic expansions. As expected, the leading order terms coincide with the proximity force approximations. We compare the results of the next-to-leading order terms of different quantum fields, and show that our results support the ansatz of derivative expansions.

  2. Vertical force acting on partly submerged spindly cylinders

    Directory of Open Access Journals (Sweden)

    Xinbin Zhang

    2014-04-01

    Full Text Available When an object is placed on a water surface, the air-water interface deforms and a meniscus arises due to surface tension effects, which in turn produces a lift force or drag force on the partly submerged object. This study aims to investigate the underlying mechanism of the vertical force acting on spindly cylinders in contact with a water surface. A simplified 2-D model is presented, and the profile of the curved air-water interface and the vertical force are computed using a numerical method. A parametric study is performed to determine the effects of the cylinder center distance, inclined angle, static contact angle, and radius on the vertical force. Several key conclusions are derived from the study: (1 Although the lift force increases with the cylinder center distance, cylinders with smaller center distances can penetrate deeper below the water surface before sinking, thereby obtaining a larger maximum lift force; (2 An increase in the inclined angle reduces the lift force, which can enable the lower cylinders fall more deeply before sinking; (3 While the effect of static contact angle is limited for angles greater than 90°, hydrophobicity allows cylinders to obtain a larger lift force and load capacity on water; (4 The lift force increases rapidly with cylinder radius, but an increase in radius also increases the overall size and weight of cylinders and decreases the proportion of the surface tension force. These findings may prove helpful in the design of supporting legs of biologically-inspired miniature aquatic devices, such as water strider robots.

  3. Scalar cylinder-plate and cylinder-cylinder Casimir interaction in higher dimensional spacetime

    CERN Document Server

    Teo, L P

    2015-01-01

    We study the cylinder-plate and the cylinder-cylinder Casimir interaction in the $(D+1)$-dimensional Minkowski spacetime due to the vacuum fluctuations of massless scalar fields. Different combinations of Dirichlet (D) and Neumann (N) boundary conditions are imposed on the two interacting objects. For the cylinder-cylinder interaction, we consider the case where one cylinder is inside the other, and the case where the two cylinders are outside each other. By computing the transition matrices of the objects and the translation matrices that relate different coordinate systems, the explicit formulas for the Casimir interaction energies are derived. Using perturbation technique, we compute the small separation asymptotic expansions of the Casimir interaction energies up to the next-to-leading order terms. The leading terms coincide with the respective results obtained using proximity force approximation, which is of order $d^{-D+1/2}$, where $d$ is the distance between the two objects. The results on the next-to...

  4. Biogas facility in horizontal cylindrical construction with separated gasometer

    Energy Technology Data Exchange (ETDEWEB)

    Perwanger, A.

    1981-09-03

    A biogas facility is described with the fermenting vessel taking the form of a horizontal cylinder. A pump switches on automatically at regular intervals to remove the floating and sinking layers. An automatic pH-gauge is coupled either to the inoculant-containing vessel or to the sewage inlet. The fermenting vessel is heated by means of tube coils, and the biogas formed is collected in a wet gasometer.

  5. Scattering by a nihility cylinder

    CERN Document Server

    Lakhtakia, A

    2006-01-01

    The total scattering and the extinction efficiencies of a nihility cylinder of infinite length and circular cross--section are identical and independent of the polarization state of a normally incident plane wave.

  6. Rotating Cylinder Treatment System Demonstration

    Science.gov (United States)

    In August 2008, a rotating cylinder treatment system (RCTSTM) demonstration was conducted near Gladstone, CO. The RCTSTM is a novel technology developed to replace the aeration/oxidation and mixing components of a conventional lime precipitation treatment s...

  7. Estudio del horizonte local

    OpenAIRE

    Ros Ferré, Rosa Maria

    2009-01-01

    El estudio del horizonte es fundamental para poder facilitar las primeras observaciones de los alumnos en un centro educativo. Un simple modelo, que debe realizarse para cada centro, nos permite facilitar el estudio y la comprensión de los primeros rudimentos astronómicos. El modelo construido se presenta a su vez como un sencillo modelo de reloj ecuatorial y a partir de él se pueden construir otros modelos (horizontal y vertical).

  8. Horizontal Integration of Knowledge

    Czech Academy of Sciences Publication Activity Database

    Klimešová, Dana; Vostrovský, V.

    Palma de Mallorca: IASTED, 2008, s. 191-196. ISBN 978-0-88986-755-0. [ Artificial Intelligence and Soft Computing (ASC 2008). Palma de Mallorca (ES), 01.09.2008-03.09.2008] Institutional research plan: CEZ:AV0Z10750506 Keywords : Intelligent systems * horizontal knowledge integration * multi-criteria evaluation * decision support Subject RIV: IN - Informatics, Computer Science http://library.utia.cas.cz/separaty/2008/ZOI/klimesova-horizontal integration of knowledge.pdf

  9. Casimir force between eccentric cylinders

    OpenAIRE

    Dalvit, Diego A. R.; Lombardo, Fernando C.; Mazzitelli, Francisco D.; Onofrio, Roberto

    2004-01-01

    We consider the Casimir interaction between a cylinder and a hollow cylinder, both conducting, with parallel axis and slightly different radii. The Casimir force, which vanishes in the coaxial situation, is evaluated for both small and large eccentricities using the proximity approximation. The cylindrical configuration offers various experimental advantages with respect to the parallel planes or the plane-sphere geometries, leading to favourable conditions for the search of extra-gravitation...

  10. Optimization of compound pressure cylinders

    OpenAIRE

    G.H. Majzoobi; A. Ghomi

    2006-01-01

    Purpose: The purpose of this paper is optimization of the weight of compound cylinder for a specific pressure. The variables are shrinkage radius and shrinkage tolerance.Design/methodology/approach: SEQ technique for optimization, the finite element code, ANSYS for numerical simulation are employed to predict the optimized conditions. The results are verified by testing a number of closed end cylinders with various geometries, materials and internal pressures.Findings: The weight of a compoun...

  11. Scalar cylinder-plate and cylinder-cylinder Casimir interaction in higher dimensional spacetime

    Science.gov (United States)

    Teo, Lee-Peng

    2015-07-01

    We study the cylinder-plate and the cylinder-cylinder Casimir interaction in the (D +1 )-dimensional Minkowski spacetime due to the vacuum fluctuations of massless scalar fields. Different combinations of Dirichlet (D) and Neumann (N) boundary conditions are imposed on the two interacting objects. For the cylinder-cylinder interaction, we consider the case where one cylinder is inside the other and the case where the two cylinders are outside each other. By computing the transition matrices of the objects and the translation matrices that relate different coordinate systems, the explicit formulas for the Casimir interaction energies are derived. From these formulas, we compute the large separation and small separation asymptotic behaviors of the Casimir interaction. For the cylinder-plate interaction with R ≪L , where R is the radius of the cylinder and L is the distance from the center of the cylinder to the plate, the order of decay of the Casimir interaction only depends on the boundary conditions imposed on the cylinder. The orders are L-D +1/ln (L ) and L-D -1/ln L , respectively, for the Dirichlet and Neumann boundary conditions on the cylinder. For two cylinders with radii R1 and R2 lying parallelly outside each other, the orders of decay of the Casimir interaction energies when R1+R2≪L are L-D +1/(ln L )2, L-D -1/ln L , and L-D -3, respectively, for DD, DN/ND, and NN boundary conditions, where L is the distance between the centers of the cylinders. The more interesting and important characteristic of Casimir interaction appears at small separation. Using the perturbation technique, we compute the small separation asymptotic expansions of the Casimir interaction energies up to the next-to-leading-order terms. The leading terms coincide with the respective results obtained using the proximity force approximation, which is of order d-D +1 /2 , where d is the distance between the two objects. The results on the next-to-leading-order terms are more

  12. Angular and Linear Accelerations of a Rolling Cylinder Acted by an External Force

    Science.gov (United States)

    Oliveira, V.

    2011-01-01

    The dynamics of a cylinder rolling on a horizontal plane acted on by an external force applied at an arbitrary angle is studied with emphasis on the directions of the acceleration of the centre-of-mass and the angular acceleration of the body. If rolling occurs without slipping, there is a relationship between the directions of these…

  13. Qualitative Changes in Flow Pattern in the Coating Flow inside a Rotating Cylinder.

    Science.gov (United States)

    Thoroddsen, S. T.

    1996-11-01

    We describe experimental work on the flow patterns in coating flow inside a partially-filled circular cylinder, which is rotated about its horizontally placed axis of symmetry. A prominent front forms at the bottom of the cylinder, associated with a recirculating region. This front is initially straight along the span. For a limited range of parameters, the front develops robust spanwise undulations, named shark teeth (S. T. Thoroddsen & L. Mahadevan, ``Experimental study of coating flows in a partially-filled horizontally rotating cylinder''), Experiments in Fluids (in press).. An intricate three-dimensional flow field is associated with these patterns. We study here the qualitative changes in the flow field associated with the transition of these shark teeth into waves traveling spanwise along the front. The wavelength and speed of these waves is investigated.

  14. Wetting on Lines and Lattices of Cylinders

    OpenAIRE

    Osborn, W. R.; Yeomans, J. M.

    1994-01-01

    This paper discusses wetting and capillary condensation transitions on a line and a rectangular array of cylinders using an interface potential formalism. For a line of cylinders, there is a capillary condensation transition followed by complete wetting if the cylinders are sufficiently close together. Both transitions disappear as the cylinder separation is increased. The dependence of the wetting phase diagram of a rectangular array of cylinders is discussed as a function of the chemical po...

  15. Triadic instability of a non-resonant precessing fluid cylinder

    CERN Document Server

    Lagrange, R; Eloy, C

    2015-01-01

    Flows forced by a precessional motion can exhibit instabilities of crucial importance, whether they concern the fuel of a flying object or the liquid core of a telluric planet. So far, stability analyses of these flows have focused on the special case of a resonant forcing. Here, we address the instability of the flow inside a precessing cylinder in the general case. We first show that the base flow forced by the cylinder precession is a superposition of a vertical or horizontal shear flow and an infinite sum of forced modes. We then perform a linear stability analysis of this base flow by considering its triadic resonance with two free Kelvin modes. Finally, we derive the amplitude equations of the free Kelvin modes and obtain an expression of the instability threshold and growth rate.

  16. Triadic instability of a non-resonant precessing fluid cylinder

    Science.gov (United States)

    Lagrange, Romain; Meunier, Patrice; Eloy, Christophe

    2016-06-01

    Flows forced by a precessional motion can exhibit instabilities of crucial importance, whether they concern the fuel of a flying object or the liquid core of a telluric planet. So far, stability analyses of these flows have focused on the special case of a resonant forcing. Here, we address the instability of the flow inside a precessing cylinder in the general case. We first show that the base flow forced by the cylinder precession is a superposition of a vertical or horizontal shear flow and of an infinite sum of forced modes. We then perform a linear stability analysis of this base flow by considering its triadic resonance with two free Kelvin modes. Finally, we derive the amplitude equations of the free Kelvin modes and obtain an expression of the instability threshold and growth rate. xml:lang="fr"

  17. Experimental study on free convection of sodium in a long cylinder

    Science.gov (United States)

    Kolesnichenko, I. V.; Mamykin, A. D.; Pavlinov, A. M.; Pakholkov, V. V.; Rogozhkin, S. A.; Frick, P. G.; Khalilov, R. I.; Shepelev, S. F.

    2015-06-01

    The operation experience of sodium fast reactor shows that during design-basis validation of pipelines and equipment it is necessary to take into account the sodium free convection in the enclosures. The paper presents the results of experimental study of free convection of liquid sodium in a long thermo-insulated cylinder with the end heat supply and removal. The sodium-filled cylinder diameter is 168 mm, length is 850 mm. Three experiments for horizontal, inclined (at 45° to a vertical line) and vertical position of the cylinder were compared in detail. The Rayleigh number (based on cylinder diameter) is approximately same for three experiments and is equal to 5 × 106. The structure of large-scale and small-scale flows was analyzed. Nusselt number estimations being the intensity measure of heat transfer in case of free convection were obtained. A relationship between the flow structure and the Nusselt number is revealed.

  18. Numerical analysis of two and three dimensional buoyancy driven water-exit of a circular cylinder

    Directory of Open Access Journals (Sweden)

    Moshari Shahab

    2014-06-01

    Full Text Available With the development of the technology of underwater moving bodies, the need for developing the knowledge of surface effect interaction of free surface and underwater moving bodies is increased. Hence, the two-phase flow is a subject which is interesting for many researchers all around the world. In this paper, the non-linear free surface deformations which occur during the water-exit of a circular cylinder due to its buoyancy are solved using finite volume discretization based code, and using Volume of Fluid (VOF scheme for solving two phase flow. Dynamic mesh model is used to simulate dynamic motion of the cylinder. In addition, the effect of cylinder mass in presence of an external force is studied. Moreover, the oblique exit and entry of a circular cylinder with two exit angles is simulated. At last, water-exit of a circular cylinder in six degrees of freedom is simulated in 3D using parallel processing. The simulation errors of present work (using VOF method for maximum velocity and height of a circular cylinder are less than the corresponding errors of level set method reported by previous researchers. Oblique exit shows interesting results; formation of waves caused by exit of the cylinder, wave motion in horizontal direction and the air trapped between the waves are observable. In 3D simulation the visualization of water motion on the top surface of the cylinder and the free surface breaking on the front and back faces of the 3D cylinder at the exit phase are observed which cannot be seen in 2D simulation. Comparing the results, 3D simulation shows better agreement with experimental data, specially in the maximum height position of the cylinder.

  19. Horizontal carbon nanotube alignment.

    Science.gov (United States)

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies. PMID:27546174

  20. Small black holes on cylinders

    International Nuclear Information System (INIS)

    We find the metric of small black holes on cylinders, i.e. neutral and static black holes with a small mass in d-dimensional Minkowski space times a circle. The metric is found using an ansatz for black holes on cylinders proposed in J. High Energy Phys. 05, 032 (2002). We use the new metric to compute corrections to the thermodynamics which is seen to deviate from that of the (d+1)-dimensional Schwarzschild black hole. Moreover, we compute the leading correction to the relative binding energy which is found to be non-zero. We discuss the consequences of these results for the general understanding of black holes and we connect the results to the phase structure of black holes and strings on cylinders

  1. PERCOLATION OF RANDOM CYLINDER AGGREGATES

    Directory of Open Access Journals (Sweden)

    Dominique Jeulin

    2011-05-01

    Full Text Available The percolation threshold ρc of Boolean models of cylinders with their axis parallel to a given direction is studied by means of simulations. An efficient method of construction of percolating connected components was developed, and is applied to one or two scales Boolean model, in order to simulate the presence of aggregates. The invariance of the percolation threshold with respect to affine transformations in the common direction of the axis of cylinders is approximately satisfied on simulations. The prediction of the model (ρc close to 0.16 is consistent with experimental measurements on plasma spray coatings, which motivated this study.

  2. Affine varieties with equivalent cylinders

    OpenAIRE

    Yu, JT; Shpilrain, V

    2001-01-01

    A well-known cancellation problem asks when, for two algebraic varieties $V_1, V_2 \\subseteq {\\bf C}^n$, the isomorphism of the cylinders $V_1 \\times {\\bf C}$ and $V_2 \\times {\\bf C}$ implies the isomorphism of $V_1$ and $V_2$. In this paper, we address a related problem: when the equivalence (under an automorphism of ${\\bf C}^{n+1}$) of two cylinders $V_1 \\times {\\bf C}$ and $V_2 \\times {\\bf C}$ implies the equivalence of their bases $V_1$ and $V_2$ under an automorphism of ${\\bf C}^n$? We c...

  3. Enhancement of polarizabilities of cylinders with cylinder-slab resonances

    Science.gov (United States)

    Xiao, Meng; Huang, Xueqin; Liu, H.; Chan, C. T.

    2015-02-01

    If an object is very small in size compared with the wavelength of light, it does not scatter light efficiently. It is hence difficult to detect a very small object with light. We show using analytic theory as well as full wave numerical calculation that the effective polarizability of a small cylinder can be greatly enhanced by coupling it with a superlens type metamaterial slab. This kind of enhancement is not due to the individual resonance effect of the metamaterial slab, nor due to that of the object, but is caused by a collective resonant mode between the cylinder and the slab. We show that this type of particle-slab resonance which makes a small two-dimensional object much ``brighter'' is actually closely related to the reverse effect known in the literature as ``cloaking by anomalous resonance'' which can make a small cylinder undetectable. We also show that the enhancement of polarizability can lead to strongly enhanced electromagnetic forces that can be attractive or repulsive, depending on the material properties of the cylinder.

  4. Optimization and improvement of Halbach cylinder design

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders; Pryds, Nini

    2008-01-01

    In this paper we describe the results of a parameter survey of a 16 segmented Halbach cylinder in three dimensions in which the parameters internal radius, rin, external radius, rex, and length, L, have been varied. Optimal values of rex and L were found for a Halbach cylinder with the least...... possible volume of magnets with a given mean flux density in the cylinder bore. The volume of the cylinder bore could also be significantly increased by only slightly increasing the volume of the magnets, for a fixed mean flux density. Placing additional blocks of magnets on the end faces of the Halbach...... cylinder also improved the mean flux density in the cylinder bore, especially so for short Halbach cylinders with large rex. Moreover, magnetic cooling as an application for Halbach cylinders was considered. A magnetic cooling quality parameter, Lambdacool, was introduced and results showed that this...

  5. Video Analysis of Rolling Cylinders

    Science.gov (United States)

    Phommarach, S.; Wattanakasiwich, P.; Johnston, I.

    2012-01-01

    In this work, we studied the rolling motion of solid and hollow cylinders down an inclined plane at different angles. The motions were captured on video at 300 frames s[superscript -1], and the videos were analyzed frame by frame using video analysis software. Data from the real motion were compared with the theory of rolling down an inclined…

  6. Modelling of Flow around Two Aligned Cylinders

    DEFF Research Database (Denmark)

    Pedersen, Ronnie; Leth, Søren

    2009-01-01

    Flow around two cylinders is considered, where closed form solutions are compared to numerical results in order to justify the practical use of the theoretical solutions when the flow in front of the cylinders is analysed. For a relatively highly mutual distance between the cylinders the numerica...... and analytical results are comparable. Opposite, when the cylinders are closely placed the potential flow solutions become inadequate compared to the numerical findings....

  7. Modelling of Flow around Two Aligned Cylinders

    OpenAIRE

    Pedersen, Ronnie; Leth, Søren

    2009-01-01

    Flow around two cylinders is considered, where closed form solutions are compared to numerical results in order to justify the practical use of the theoretical solutions when the flow in front of the cylinders is analysed. For a relatively highly mutual distance between the cylinders the numerical and analytical results are comparable. Opposite, when the cylinders are closely placed the potential flow solutions become inadequate compared to the numerical findings.

  8. Thermal characteristics of condensing steam in a single horizontal mini-channel with triangular shape

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jae Hee; Hwang, Kyo Sik; Ha, Hyo Jun; Jang, Seok Pil [Korea Aerospace Univ., Goyang (Korea, Republic of); Lee, Ki Woo [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2009-07-01

    In the papermaking processes it is well known that the dryer uses the largest amount of energy and has costly components compared with other devices. Many researchers thus conducted to reduce energy and cost of the dryer. Recently Argonne national laboratory has developed the concept of a multiport cylinder dryer that the steam flows along longitudinally oriented mini-channels which are close to inner surface of cylinder dryer. They reported that the innovative design minimizes the condensate layer thickness. However, systematically experimental data are not available. So in this paper we will conduct experiments to study thermal characteristics of condensing steam in a single horizontal mini-channel with triangular shape, representative of a multiport cylinder dryer. Based on the results, we confirm previous results and observe the condensing heat transfer coefficient in the single horizontal mini-channel with triangular shape.

  9. Thermal characteristics of condensing steam in a single horizontal mini-channel with triangular shape

    International Nuclear Information System (INIS)

    In the papermaking processes it is well known that the dryer uses the largest amount of energy and has costly components compared with other devices. Many researchers thus conducted to reduce energy and cost of the dryer. Recently Argonne national laboratory has developed the concept of a multiport cylinder dryer that the steam flows along longitudinally oriented mini-channels which are close to inner surface of cylinder dryer. They reported that the innovative design minimizes the condensate layer thickness. However, systematically experimental data are not available. So in this paper we will conduct experiments to study thermal characteristics of condensing steam in a single horizontal mini-channel with triangular shape, representative of a multiport cylinder dryer. Based on the results, we confirm previous results and observe the condensing heat transfer coefficient in the single horizontal mini-channel with triangular shape.

  10. Conceptualising horizontal politics

    OpenAIRE

    Harding, Eloise Mary

    2012-01-01

    This project investigates the likelihood of a distinctive ideology emerging from what are known as ‘horizontal’ political movements – those which, in brief, aim to operate non-hierarchically guided by principles such as affinity – and furthermore to identify the potential components of such an ideology. The methodology is broadly based on that developed by Freeden, namely an analysis of the conceptual morphology of the ideas put out by horizontal movements. The sources used derive largely fro...

  11. Numerical analysis the influence of the rotating cylinder in transitional flow in annular channels

    International Nuclear Information System (INIS)

    In this paper, numerical experiments were performed to analyze the effects of the rotating cylinder over transitional flow between two horizontal concentric cylinders. The unstable and oscillatory flow was predicted using the large-eddy simulation methodology with dynamic sub-grid scale model. Three-dimensional aspects of transition to turbulence at Rayleigh number Ra =1.7 x 105 and Froude number range of 0.05 ≤ Fr ≤ ∞ was obtained, as well as the effects of the centrifugal force on the heat transfer process was analyzed. (authors)

  12. Enhancement of polarizabilities of cylinders with cylinder-slab resonances

    CERN Document Server

    Xiao, Meng; Liu, H; Chan, C T

    2014-01-01

    If an object is very small in size compared with the wavelength of light, it does not scatter light efficiently. It is hence difficult to detect a very small object with light. We show using analytic theory as well as full wave numerical calculation that the effective polarizability of a small cylinder can be greatly enhanced by coupling it with a superlens type metamaterial slab. This kind of enhancement is not due to the individual resonance effect of the metamaterial slab, nor due to that of the object, but is caused by a collective resonant mode between the cylinder and the slab. We show that this type of particle-slab resonance which makes a small two-dimensional object much brighter is actually closely related to the reverse effect known in the literature as cloaking by anomalous resonance which can make a small cylinder undetectable. We also show that the enhancement of polarizability can lead to strongly enhanced electromagnetic forces that can be attractive or repulsive, depending on the material pro...

  13. Massless rotating fermions inside a cylinder

    International Nuclear Information System (INIS)

    We study rotating thermal states of a massless quantum fermion field inside a cylinder in Minkowski space-time. Two possible boundary conditions for the fermion field on the cylinder are considered: the spectral and MIT bag boundary conditions. If the radius of the cylinder is sufficiently small, rotating thermal expectation values are finite everywhere inside the cylinder. We also study the Casimir divergences on the boundary. The rotating thermal expectation values and the Casimir divergences have different properties depending on the boundary conditions applied at the cylinder. This is due to the local nature of the MIT bag boundary condition, while the spectral boundary condition is nonlocal

  14. Massless rotating fermions inside a cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Ambruş, Victor E., E-mail: victor.ambrus@gmail.com [Center for Fundamental and Advanced Technical Research, Romanian Academy Bd. Mihai Viteazul 24, 300223 Timişoara (Romania); Winstanley, Elizabeth [School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH (United Kingdom)

    2015-12-07

    We study rotating thermal states of a massless quantum fermion field inside a cylinder in Minkowski space-time. Two possible boundary conditions for the fermion field on the cylinder are considered: the spectral and MIT bag boundary conditions. If the radius of the cylinder is sufficiently small, rotating thermal expectation values are finite everywhere inside the cylinder. We also study the Casimir divergences on the boundary. The rotating thermal expectation values and the Casimir divergences have different properties depending on the boundary conditions applied at the cylinder. This is due to the local nature of the MIT bag boundary condition, while the spectral boundary condition is nonlocal.

  15. Fluid Flow Through Triangular and Square Cylinders

    OpenAIRE

    Salam, Nasaruddin

    2014-01-01

    Characteristicsof fluid flowing through triangular and square cylindershas been analyzed experimentally andnumerically by CFDat Reynolds number based on square cylinders diameter,Re = 14.730;26.040 and 37.192. Ratio of the distance between cylinders to square cylinders diameter (L/D) was variedas0.0;1.0; 2.0; 3.0; 4.0; and 5.0 while ratio of the triangular cylinders diameter to square cylinders diameter (d/D) was constant at 0.5. The results showed that the vortex is damped...

  16. Connectedness of Poisson cylinders in Euclidean space

    OpenAIRE

    Broman, Erik I.; Tykesson, Johan

    2013-01-01

    We consider the Poisson cylinder model in $\\mathbb{R}^{d}$, $d\\ge3$. We show that given any two cylinders ${\\mathfrak{c}}_{1}$ and ${\\mathfrak{c}}_{2}$ in the process, there is a sequence of at most $d-2$ other cylinders creating a connection between ${\\mathfrak{c}}_{1}$ and ${\\mathfrak{c}}_{2}$. In particular, this shows that the union of the cylinders is a connected set, answering a question appearing in (Probab. Theory Related Fields 154 (2012) 165–191). We also show that there are cylinde...

  17. Effective surface motion on a reactive cylinder of particles that perform intermittent bulk diffusion

    OpenAIRE

    Chechkin, Aleksei V.; Zaid, Irwin M.; Lomholt, Michael A; Sokolov, Igor M.; Metzler, Ralf

    2011-01-01

    In many biological and small scale technological applications particles may transiently bind to a cylindrical surface. In between two binding events the particles diffuse in the bulk, thus producing an effective translation on the cylinder surface. We here derive the effective motion on the surface, allowing for additional diffusion on the cylinder surface itself. We find explicit solutions for the number of adsorbed particles at one given instant, the effective surface displacement, as well ...

  18. Electrostatics of spherical metallic particles in cylinder electrostatic separators/sizers

    International Nuclear Information System (INIS)

    This paper presents a theoretical analysis of the dynamics of spherical metallic particles in electrostatic separators/sizers (ESSs). A computational algorithm is employed to depict the cylinder-type electrode arrangements applied in some electrostatic processes generating non-uniform electric fields. The ESS consists of a pair of conducting cylinders. The upper cylinder is energized by HVdc, while the lower one is grounded and mounted horizontally on a revolvable axis. The aim of this paper is to present a new electrode configuration and demonstrate the usefulness of numerical techniques for the evaluation of the particle's motion. A computer program was employed for analysing the behavior of spherical particles in a two-dimensional electrode arrangement that models the actual electric field configuration of cylinder-type electrostatic separators/sizers. The analysis is needed for the development of any new application of this cylinder-type electrode arrangement as an electrostatic separation method. The results reveal that the particle's motion depends on its radius and density and amplitude of the applied voltage. The actual granular mixtures with different specific mass and radius could be separated applying this cylinder-type electrostatic separation method; the lift voltage is an important parameter for separation. With a program for two-dimensional analysis of the electric field, the computational procedure presented in this paper could be employed for any particle shapes

  19. Finite element analysis of second order wave radiation by a group of cylinders in the time domain

    Institute of Scientific and Technical Information of China (English)

    WANG Chi-zhong; MITRA Santanu; HUANG Hao-cai; KHOO Boo-cheong

    2013-01-01

    A finite element based numerical method is employed to analyze the wave radiation by multiple or a group of cylinders in the time domain.The nonlinear free surface and body surface boundary conditions are satisfied based on the perturbation method up to the second order.The first-and second-order velocity potential problems at each time step are solved through a Finite Element Method (FEM).The matrix equation of the FEM is solved through iteration and the initial solution is obtained from the result at the previous time step.The three-dimensional (3-D) mesh required is generated based on a two-dimensional (2-D) hybrid mesh on a horizontal plane and its extension in the vertical direction.The hybrid mesh is generated by combining an unstructured grid away from cylinders and two structured grids near the cylinder and the artificial boundary.The fluid velocity on the free surface and the cylinder surface are calculated by using a differential method.Results for various configurations including the cases of two cylinders and four cylinders and a group of eighteen cylinders are obtained to show the joint influences of cylinders on the first-and secondorder waves and forces,including the effects of spacing ratios and wave frequency on the second order waves and the mean force,in particular.

  20. Horizontally rotated cell culture system with a coaxial tubular oxygenator

    Science.gov (United States)

    Wolf, David A. (Inventor); Schwarz, Ray P. (Inventor); Trinh, Tinh T. (Inventor)

    1991-01-01

    The present invention relates to a horizontally rotating bioreactor useful for carrying out cell and tissue culture. For processing of mammalian cells, the system is sterilized and fresh fluid medium, microcarrier beads, and cells are admitted to completely fill the cell culture vessel. An oxygen containing gas is admitted to the interior of the permeable membrane which prevents air bubbles from being introduced into the medium. The cylinder is rotated at a low speed within an incubator so that the circular motion of the fluid medium uniformly suspends the microbeads throughout the cylinder during the cell growth period. The unique design of this cell and tissue culture device was initially driven by two requirements imposed by its intended use for feasibility studies for three dimensional culture of living cells and tissues in space by JSC. They were compatible with microgravity and simulation of microgravity in one G. The vessels are designed to approximate the extremely quiescent low shear environment obtainable in space.

  1. Rolling Cylinder Phase 1bis

    DEFF Research Database (Denmark)

    Margheritini, Lucia

    This report has been prepared under the contract agreement between Aalborg Universitet and Storper Innovation ApS. The report has been written by Lucia Margheritini (lm@civil.aau.dk) who is also responsible for the data analysis. This report is the continuation of the previous report “Rolling...... Cylinder Phase 1: proof of concept and first optimization”, DCE report 115, ISSN 1901-726X, and it is recommended that the two are consulted together as they were firstly agreed to be in one document. The present report aims at estimate the efficiency of the Rolling Cylinder long model (previously...... optimized), by mean of physical tests in irregular waves. Several difficulties have been encountered during the testing, the biggest of witch being the extremely unfriendly torque measuring system....

  2. Cylinder components properties, applications, materials

    CERN Document Server

    2016-01-01

    Owing to the ever-increasing requirements to be met by gasoline and diesel engines in terms of CO2 reduction, emission behavior, weight, and service life, a comprehensive understanding of combustion engine components is essential today. It is no longer possible for professionals in automotive engineering to manage without the corresponding expertise, whether they work in the field of design, development, testing, or maintenance. This technical book provides in-depth answers to questions about design, production, and machining of cylinder components. In this second edition, every section has been revised and expanded to include the latest developments in the combustion engine. Content Piston rings Piston pins and piston pin circlips Bearings Connecting rods Crankcase and cylinder liners Target audience Engineers in the field of engine development and maintenanceLecturers and students in the areas of mechanical engineering, engine technology, and vehicle constructionAnyone interested in technology Publisher MAH...

  3. Water Wave Scattering by a Nearly Circular Cylinder Submerged Beneath an Ice-cover

    Institute of Scientific and Technical Information of China (English)

    Rumpa Chakraborty; Birendra Nath Mandal

    2015-01-01

    Assuming linear theory, the two-dimensional problem of water wave scattering by a horizontal nearly circular cylinder submerged in infinitely deep water with an ice cover modeled as a thin-elastic plate floating on water, is investigated here. The cross-section of the nearly circular cylinder is taken as r=a(1+δC(θ)), wherea is the radius of the corresponding circular cross-section of the cylinder,δ is a measure of small departure of the cross-section of the cylinder from its circularity andC(θ) is the shape function. Using a simplified perturbation technique the problem is reduced to two independent boundary value problems up to first order inδ. The first one corresponds to water wave scattering by a circular cylinder submerged in water with an ice-cover, while the second problem describes wave radiation by a submerged circular cylinder and involves first order correction to the reflection and transmission coefficients. The corrections are obtained in terms of integrals involving the shape function. Assuming a general Fourier expansion of the shape function, these corrections are evaluated approximately. It is well known that normally incident wave trains experience no reflection by a circular cylinder submerged in infinitely deep water with an ice cover. It is shown here that the reflection coefficient also vanishes up to first order for some particular choice of the shape function representing a nearly circular cylinder. For these cases, full transmission occurs, only change is in its phase which is depicted graphically against the wave number in a number of figures and appropriate conclusions are drawn.

  4. Experimental Study of Wave Forces on Vertical Circular Cylinders in Long and Short Crested Sea

    DEFF Research Database (Denmark)

    Høgedal, Michael

    in the transverse wave forces on the structure, whereas the vertical forces generally are unaffected. In this study the effect from wave directionality on the horizontal wave forces on a slender vertical cylinder in a laboratory environment is investigated. In addition wave forces from regular waves......The three-dimensional structure of ocean waves is generally ignored in favour of two-dimensional waves, which are easier to handle from a theoretical and computational point of view. For design fixed structures where horizontal in-line and resultant wave forces are important, this is normally on...... the safe side, as the directional spreading of the wave field Ieads to reduced horizontal velocities and acceleration; in the fluid and hence a reduction of the resultant and in-line wave forces on the structure. The directional spreading of the horizontal velocity field generally causes an increase...

  5. Fire testing of bare uranium hexafluoride cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Pryor, W.A. [PAI Corp., Oak Ridge, TN (United States)

    1991-12-31

    In 1965, the Oak Ridge Gaseous Diffusion Plant (ORGDP), now the K-25 Site, conducted a series of tests in which bare cylinders of uranium hexafluoride (UF{sub 6}) were exposed to engulfing oil fires for the US Atomic Energy Commission (AEC), now the US Department of Energy (DOE). The tests are described and the results, conclusions, and observations are presented. Two each of the following types of cylinders were tested: 3.5-in.-diam {times} 7.5-in.-long cylinders of Monel (Harshaw), 5.0-in.-diam {times} x 30-in.-long cylinders of Monel, and 8-in.-diam {times} 48-in.-long cylinders of nickel. The cylinders were filled approximately to the standard UF{sub 6} fill limits of 5, 55, and 250 lb, respectively, with a U-235 content of 0.22%. The 5-in.- and 8-in.-diam cylinders were tested individually with and without their metal valve covers. For the 3.5-in.-diam Harshaw cylinders and the 5.0-in.-diam cylinder without a valve cover, the valves failed and UF{sub 6} was released. The remaining 6 cylinders ruptured explosively in time intervals ranging from about 8.5 to 11 min.

  6. Fire testing of bare uranium hexafluoride cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Pryor, W.A. [PAI Corp., Oak Rige, TN (United States)

    1991-12-31

    In 1965, the Oak Ridge Gaseous Diffusion Plant (ORGDP), now the K-25 Site, conducted a series of tests in which bare cylinders of uranium hexafluoride (UF{sub 6}) were exposed to engulfing oil fires for the US Atomic Energy Commission (AEC), now the US Department of Energy (DOE). The tests are described and the results, conclusions, and observations are presented. Two each of the following types of cylinders were tested: 3.5-in.-diam {times} 7.5-in.-long cylinders of Monel (Harshaw), 5.0-in.-diam {times} 30-in.-long cylinders of Monel, and 8-in.-diam {times} 48-in.-long cylinders of nickel. The cylinders were filled approximately to the standard UF{sub 6} fill limits of 5, 55, and 250 lb, respectively, with a U-235 content of 0.22%. The 5-in.- and 8-in.-diam cylinders were tested individually with and without their metal valve covers. For the 3.5-in.-diam Harshaw cylinders and the 5.0-in.-diam cylinder without a valve cover the valves failed and UF{sub 6} was released. The remaining cylinders ruptured explosively in time intervals ranging from about 8.5 to 11 min.

  7. Detection of cylinder pressure in diesel engines using cylinder head vibration and time series methods

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper investigates the vibration characteristics of diesel engine cylinder heads by means of the time series method.With the concept of "Assumed System", the vibration transfer function of real cylinder head structures is established using the autoregressive-moving average models (ARMA models) of cylinder head surface vibration signals.Then this transfer function is successfully used to reconstruct the gas pressure trace inside the cylinder from measured cylinder head vibration signals.This offers an effective means for diesel engine cylinder pressure detection and condition monitoring.

  8. Augmentation of heat transfer from a solid cylinder wrapped with a porous layer

    DEFF Research Database (Denmark)

    Bhattacharyya, S.; Singh, Ashok

    In the present study, the heat transfer from a porous wrapped solid cylinder is considered. The heated cylinder is placed horizontally and is subjected to a uniform cross-flow. The aim is to investigate the heat transfer augmentation through the inclusion of a porous wrapper. The porous layer is of...... value of porous layer thickness for heat transfer augmentation and its dependence on other properties of the porous foam is obtained. The flow field is analyzed through a single domain approach in which the porous layer is considered as a pseudo-fluid and the composite region as a continuum. A pressure...... correction based iterative algorithm is used for computation. Our results show that a thin porous wrapper of high thermal conductivity can enhance the rate of heat transfer substantially. Periodic vortex shedding is observed from the porous shrouded solid cylinder for high values of Reynolds number. The...

  9. Enhancement of polarizabilities of cylinders with cylinder-slab resonances

    OpenAIRE

    Meng Xiao; Xueqin Huang; Liu, H.; Chan, C. T.

    2015-01-01

    If an object is very small in size compared with the wavelength of light, it does not scatter light efficiently. It is hence difficult to detect a very small object with light. We show using analytic theory as well as full wave numerical calculation that the effective polarizability of a small cylinder can be greatly enhanced by coupling it with a superlens type metamaterial slab. This kind of enhancement is not due to the individual resonance effect of the metamaterial slab, nor due to that ...

  10. Well Spacing for Horizontal Wells

    Directory of Open Access Journals (Sweden)

    C.D.S. Keuengoua

    2011-06-01

    Full Text Available In the developing phase of a hydrocarbon reservoir and planning for drilling the production wells, it is necessary to drill the wells in an appropriate spacing to achieve maximum economic revenues during the reservoir life span. Well spacing which is the real location and interrelationship between producing oil or gas wells in an oil field is an important parameter. It is determined for the maximum ultimate production of a given reservoir and should be taken in consideration during well planning to avoid drilling of unnecessary wells. This study presents the concept of drainage area on horizontal well and horizontal productivity indices with different equations and their applications. A user friendly Excel Spreadsheet program was developed to calculate the productivity values of horizontal wells using three major available productivity equations. Also, the developed spreadsheet program was used to evaluate the effect of well spacing on the productivities of horizontal wells using productivity index approach and drainage area concept. It also helps to review the comparison between vertical and horizontal wells spacing based on drainage area concept. This program was validated, and then was used to study the effect of horizontal well length on the ratio of horizontal well productivity to vertical well productivity. The results show that higher ratio of horizontal well productivity to vertical well productivity values are obtained with increase length of the horizontal well. It is a very useful tool for making decision about the application of well spacing for horizontal wells.

  11. Horizontally shaken impact pendulums

    Science.gov (United States)

    Alexander, T. J.; Xu, Y.; Sidhu, H.

    2016-03-01

    We consider two pendulum masses attached to the same pivot point and which interact with each other through Hertzian impacts. We show that this splitting of the mass leads to an instability in the conservative case, in which initially synchronized large amplitude motion may evolve into out-of-phase (impacting) motion. We then study in detail the response of the impacting masses in the presence of damping and driving through horizontal shaking of the pivot point. We find that synchronized modes are usually accompanied by small amplitude quasi-periodic, or even chaotic, impacts and a number of multi-period solutions may appear in the bifurcation diagram. We reveal the existence and stability of a number of impact modes and scan the frequency response of the system to a series of initial conditions to identify which modes may be more easily generated in experiment.

  12. On the flow separation in the wake of a fixed and a rotating cylinder

    Science.gov (United States)

    Miron, Philippe; Vétel, Jérôme; Garon, André

    2015-08-01

    The flow past a circular cylinder under diverse conditions is investigated to examine the nature of the different separation mechanisms that can develop. For a fixed cylinder in a uniform, steady, and horizontal stream, the alternating sheddings of vortices, characterizing the Kármán vortex street, occur from two separation points located in the rear cylinder wall. The prediction of the separation positions and profiles is examined in the light of the most recent theory of unsteady separation in two-dimensional flows. It is found that the separation points are fixed in space and located symmetrically about the horizontal axis passing through the center of the cylinder. The unsteady separation profiles are also well-predicted by the theory. If the cylinder rotates on its axis in the anti-clockwise direction, the upper and lower separation points are shifted in the upstream and the downstream direction, respectively, but are no longer attached to the wall and cannot be predicted by the theory. Instead, they are captured as saddle points in the interior of the flow without any connection to on-wall quantities, as suggested by the Moore-Rott-Sears (MRS) principle. The saddle points are detected through a Lagrangian approach as the location of maximum tangential rate of strain on Lagrangian coherent structures identified as the most attracting lines in the vicinity of the cylinder. If, in addition, the uniform stream is unsteady, the Eulerian saddle points, i.e., detected by streamlines, change position in time, but have no direct relation to the true separation points that are defined by Lagrangian saddle points, thus invalidating the MRS principle that is Eulerian by nature. Other separation mechanisms are also described and understood in view of Lagrangian identification tools.

  13. Experimental critical parameters of plutonium metal cylinders flooded with water

    International Nuclear Information System (INIS)

    Forty-nine critical configurations are reported for experiments involving arrays of 3 kg plutonium metal cylinders moderated and reflected by water. Thirty-four of these describe systems assembled in the laboratory, while 15 others are derived critical parameters inferred from 46 subcritical cases. The arrays included 2x2xN, N = 2, 3, 4, and 5, in one program and 3x3x3 configurations in a later study. All were three-dimensional, nearly square arrays with equal horizontal lattice spacings but a different vertical lattice spacing. Horizontal spacings ranged from units in contact to 180 mm center-to-center; and vertical spacings ranged from about 80 mm to almost 400 mm center-to-center. Several nearly-equilateral 3x3x3 arrays exhibit an extremely sensitive dependence upon horizontal separation for identical vertical spacings. A line array of unreflected and essentially unmoderated canned plutonium metal units appeared to be well subcritical based on measurements made to assure safety during the manual assembly operations. All experiments were performed at two widely separated times in the mid-1970s and early 1980s under two programs at the Rocky Flats Plant's Critical Mass Laboratory

  14. Experimental critical parameters of plutonium metal cylinders flooded with water

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-01

    Forty-nine critical configurations are reported for experiments involving arrays of 3 kg plutonium metal cylinders moderated and reflected by water. Thirty-four of these describe systems assembled in the laboratory, while 15 others are derived critical parameters inferred from 46 subcritical cases. The arrays included 2x2xN, N = 2, 3, 4, and 5, in one program and 3x3x3 configurations in a later study. All were three-dimensional, nearly square arrays with equal horizontal lattice spacings but a different vertical lattice spacing. Horizontal spacings ranged from units in contact to 180 mm center-to-center; and vertical spacings ranged from about 80 mm to almost 400 mm center-to-center. Several nearly-equilateral 3x3x3 arrays exhibit an extremely sensitive dependence upon horizontal separation for identical vertical spacings. A line array of unreflected and essentially unmoderated canned plutonium metal units appeared to be well subcritical based on measurements made to assure safety during the manual assembly operations. All experiments were performed at two widely separated times in the mid-1970s and early 1980s under two programs at the Rocky Flats Plant`s Critical Mass Laboratory.

  15. PRODUCTIVITY OF FRACTURED HORIZONTAL WELLS

    Directory of Open Access Journals (Sweden)

    Stjepan Antolović

    2009-12-01

    Full Text Available The interest and performance of horizontal drilling and completions has increased during the last two decades. Horizontal wells are advantageous compared to vertical wells in thin reservoirs, reservoirs with favorable vertical permeability and reservoirs with water and gas coning problems. In many reservoirs, the ratio of horizontal permeability to the vertical permeability is substantially larger than one and often is close to 10. Thus, these reservoirs are very good candidates for hydraulic fracturing. By hydraulic fracturing one or more fractures are created, which can be longitudinal or orthogonal. By that, flow is altered and it mostly conducts horizontally through reservoir toward horizontal wellbore. With this altered flow, fluid is produced faster, with less pressure loss by fluid unit of produced fluid. Some of the existing mathematical models to determine the productivity of multifractured horizontal wells are presented in this work (the paper is published in Croatian.

  16. Fatigue Tests with Densit Cylinders - D4

    DEFF Research Database (Denmark)

    Ellegaard, Peter

    This report contains descriptions and results of a series of fatigue tests performed during the autumn of 2005 at the Stuctural Research Laboratory, Aalborg University. Cylinders with a diameter of 45 mm and a height of 90 mm were used as test specimens; the material was Densit Ducorit D4. Four...... cylinders were tested statically under compression and the rest of the cylinders (30) were tested under fatigue conditions with a load varying sinusoidally....

  17. Exploring the quantum vacuum with cylinders

    OpenAIRE

    Lombardo, F. C.; Mazzitelli, F. D.; Villar, P. I.

    2008-01-01

    We review recent work on the Casimir interaction energy between cylindrical shells. We include proposals for future experiments involving cylinders, such us a null experiment using quasi-concentric cylinders, a cylinder in front a conducting plate, and a cylindrical version of the rack and pinion powered by Casimir lateral force. We also present an exact formula for the theoretical evaluation of the vacuum interaction energy between eccentric cylindrical shells, and describe improved analytic...

  18. Rarita-Schwinger Type operators on Cylinders

    OpenAIRE

    LI, JUNXIA; Ryan, John; Vanegas, Carmen J.

    2011-01-01

    Here we define Rarita-Schwinger operators on cylinders and construct their fundamental solutions. Further the fundamental solutions to the cylindrical Rarita-Schwinger type operators are achieved by applying translation groups. In turn, a Borel-Pompeiu Formula, Cauchy Integral Formula and a Cauchy Transform are presented for the cylinders. Moreover we show a construction of a number of conformally inequivalent spinor bundles on these cylinders. Again we construct Rarita-Schwinger operators an...

  19. Casimir forces between cylinders at different temperatures

    OpenAIRE

    Golyk, Vladyslav A.; Krüger, Matthias; Reid, M. T. Homer; Kardar, Mehran

    2012-01-01

    We study Casimir interactions between cylinders in thermal non-equilibrium, where the objects as well as the environment are held at different temperatures. We provide the general formula for the force, in a one reflection approximation, for cylinders of arbitrary radii and optical properties. As is the case for equilibrium, we find that the force for optically diluted cylinders can be obtained by appropriate summation of the corresponding result for spheres. We find that the non-equilibrium ...

  20. Cylinder valve packing nut studies

    Energy Technology Data Exchange (ETDEWEB)

    Blue, S.C. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    The design, manufacture, and use of cylinder valve packing nuts have been studied to improve their resistance to failure from stress corrosion cracking. Stress frozen photoelastic models have been analyzed to measure the stress concentrations at observed points of failure. The load effects induced by assembly torque and thermal expansion of stem packing were observed by strain gaging nuts. The effects of finishing operations and heat treatment were studied by the strain gage hole boring and X-ray methods. Modifications of manufacturing and operation practices are reducing the frequency of stress corrosion failures.

  1. DRILL BITS FOR HORIZONTAL WELLS

    OpenAIRE

    Paolo Macini

    1996-01-01

    This paper underlines the importance of the correct drill bit application in horizontal wells. Afler the analysis of the peculiarities of horizontal wells and drainholes drilling techniques, advantages and disadvantages of the application of both roller cone and fixed cutters drill bits have been discussed. Also, a review of the potential specific featuries useful for a correct drill bit selection in horizontal small diameter holes has been highlighted. Drill bits for these special applicatio...

  2. PRODUCTIVITY OF FRACTURED HORIZONTAL WELLS

    OpenAIRE

    2009-01-01

    The interest and performance of horizontal drilling and completions has increased during the last two decades. Horizontal wells are advantageous compared to vertical wells in thin reservoirs, reservoirs with favorable vertical permeability and reservoirs with water and gas coning problems. In many reservoirs, the ratio of horizontal permeability to the vertical permeability is substantially larger than one and often is close to 10. Thus, these reservoirs are very good candidates for hydraulic...

  3. INTERACTION OF A FLOATING ELLIPTIC CYLINDER WITH A VIBRATING CIRCULAR CYLINDER

    Institute of Scientific and Technical Information of China (English)

    SUN Ren; CHWANG Allen T.

    2006-01-01

    The nonlinear hydrodynamic interaction between a floating elliptic cylinder and a vibrating circular cylinder immersed in an infinite fluid was investigated. By taking the added masses of the two-cylinder system into account, the dynamical equations of motion were formulated from the Lagrange equations of motion. The dynamical behaviors of these two cylinders were analyzed numerically for some typical situations, and the results show that the presence of a vibrating circular cylinder has a significant influence on the planar motion of a floating elliptic cylinder. The hydrodynamic interaction between them results in complicated nonlinear behaviors of the floating cylinder. It is found that oscillatory motion of the elliptic cylinder takes place in response to the vibrating mode of the circular one.

  4. Wake flow behaviour behind a smaller cylinder oscillating in the wake of an upstream stationary cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yangyang; Sun, Zhilin [Ocean College, Zhejiang University, Hangzhou 310058 (China); Tan, Danielle S [Maritime Research Centre, Nanyang Technological University, Singapore 639798 (Singapore); Yu, Dingyong [College of Engineering, Ocean University of China, 266100 (China); Tan, Soon Keat, E-mail: yygao@zju.edu.cn [Nanyang Environment and Water Research Institute, Nanyang Technological University, Singapore 639798 (Singapore)

    2014-04-01

    The flow patterns around a cylinder oscillating freely in the wake of a larger cylinder upstream were investigated using the particle image velocimetry technique. The upstream cylinder was fixed at both ends while the downstream smaller cylinder was held by springs such that it was free to oscillate in the transverse direction. The flow patterns, amplitudes of oscillation and vortex shedding frequencies were compared with those of a single cylinder. In the presence of the upstream cylinder, the three parameters characterizing the oscillation response of the smaller cylinder—amplitude of oscillation, vortex shedding frequency and Reynolds stresses—were greatly reduced. While their magnitude increased with gap ratio, these three parameters were still smaller than the corresponding magnitudes for a single oscillating cylinder. The peak values of turbulence statistics such as Reynolds shear stress and normal stress behind the oscillating downstream cylinder were similarly reduced, and increased with gap ratios. (paper)

  5. Wake flow behaviour behind a smaller cylinder oscillating in the wake of an upstream stationary cylinder

    International Nuclear Information System (INIS)

    The flow patterns around a cylinder oscillating freely in the wake of a larger cylinder upstream were investigated using the particle image velocimetry technique. The upstream cylinder was fixed at both ends while the downstream smaller cylinder was held by springs such that it was free to oscillate in the transverse direction. The flow patterns, amplitudes of oscillation and vortex shedding frequencies were compared with those of a single cylinder. In the presence of the upstream cylinder, the three parameters characterizing the oscillation response of the smaller cylinder—amplitude of oscillation, vortex shedding frequency and Reynolds stresses—were greatly reduced. While their magnitude increased with gap ratio, these three parameters were still smaller than the corresponding magnitudes for a single oscillating cylinder. The peak values of turbulence statistics such as Reynolds shear stress and normal stress behind the oscillating downstream cylinder were similarly reduced, and increased with gap ratios. (paper)

  6. Rotating cylinder design as a lifting generator

    International Nuclear Information System (INIS)

    The airfoil shape of a wing has always been the design to generate lift. But few realized that a simple rotating cylinder can also create lift. However, the explanation and study of how a rotating cylinder creates lift are still complex. In remote area where it is difficult for air vehicle to access, the exploration and discovery of different configuration for design concept is rather important. Due to this reason, there is a need to think of a lift generator that can produce better lift (few fold better than conventional airfoil) at lower speed to take off in a short distance of time. This paper will explain the conditions and the design of such a wing using the rotating cylinder concept that will take off in a short time and requires little takeoff and landing strip. Spokes will be attached to the cylinder to force the surrounding air to rotate along with the cylinder. This will create a vortex that hastens the speed of the air on top of the cylinder and at the same time retarding the speed of air below the cylinder. From the results, the rougher surface cylinder produces more lift when rotating and also, higher speed rotation of the cylinder greatly changes the speed of the surrounding air, thus better lift

  7. Overseas shipments of 48Y cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, R.T.; Furlan, A.S. [Cameco Corp., Port Hope, Ontario (Canada)

    1991-12-31

    This paper describes experiences with two incidents of overseas shipments of uranium hexafluoride (UF{sub 6}) cylinders. The first incident involved nine empty UF{sub 6} cylinders in enclosed sea containers. Three UF{sub 6} cylinders broke free from their tie-downs and damaged and contaminated several sea containers. This paper describes briefly how decontamination was carried out. The second incident involved a shipment of 14 full UF{sub 6} cylinders. Although the incident did not cause an accident, the potential hazard was significant. The investigation of the cause of the near accident is recounted. Recommendations to alleviate future similar incidents for both cases are presented.

  8. Fire exposure of empty 30B cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Ziehlke, K.T. [MJB Technical Associates, Inc., Knoxville, TN (United States)

    1991-12-31

    Cylinders for UF{sub 6} handling, transport, and storage are designed and built as unfired pressure vessels under ASME Boiler and Pressure Vessel Code criteria and standards. They are normally filled and emptied while UF{sub 6} is in its liquid phase. Transport cylinders such as the Model 30B are designed for service at 200 psi and 250{degrees}F, to sustain the process conditions which prevail during filling or emptying operations. While in transport, however, at ambient temperature the UF{sub 6} is solid, and the cylinder interior is well below atmospheric pressure. When the cylinders contain isotopically enriched product (above 1.0 percent U-235), they are transported in protective overpacks which function to guard the cylinders and their contents against thermal or mechanical damage in the event of possible transport accidents. Two bare Model 30B cylinders were accidentally exposed to a storage warehouse fire in which a considerable amount of damage was sustained by stored materials and the building structure, as well as by the cylinder valves and valve protectors. The cylinders were about six years old, and had been cleaned, inspected, hydrotested, and re-certified for service, but were still empty at the time of the fire. The privately-owned cylinders were transferred to DOE for testing and evaluation of the fire damage.

  9. Solvable Critical Dense Polymers on the Cylinder

    OpenAIRE

    Pearce, Paul A.; Rasmussen, Jorgen; Villani, Simon P.

    2009-01-01

    A lattice model of critical dense polymers is solved exactly on a cylinder with finite circumference. The model is the first member LM(1,2) of the Yang-Baxter integrable series of logarithmic minimal models. The cylinder topology allows for non-contractible loops with fugacity alpha that wind around the cylinder or for an arbitrary number ell of defects that propagate along the full length of the cylinder. Using an enlarged periodic Temperley-Lieb algebra, we set up commuting transfer matrice...

  10. On vortex shedding from a hexagonal cylinder

    International Nuclear Information System (INIS)

    The unsteady wake behind a hexagonal cylinder in cross-flow is investigated numerically. The time-dependent three-dimensional Navier-Stokes equations are solved for three different Reynolds numbers Re and for two different cylinder orientations. The topology of the vortex shedding depends on the orientation and the Strouhal frequency is generally higher in the wake of a face-oriented cylinder than behind a corner-oriented cylinder. For both orientations a higher Strouhal number St is observed when Re is increased from 100 to 500 whereas St is unaffected by a further increase up to Re=1000. The distinct variation of St with the orientation of the hexagonal cylinder relative to the oncoming flow is opposite of earlier findings for square cylinder wakes which exhibited a higher St with corner orientation than with face orientation. -- Highlights: → The first direct numerical simulation on hexagonal cylinder. → The Letter focuses on vortex shedding from a 3D hexagonal cylinder. → Two orientations and 3 Reynolds numbers are considered. → Variation of Strouhal number between hexagonal and square cylinder is discussed.

  11. Swap your propane cylinder with SWOP

    International Nuclear Information System (INIS)

    A very successful propane cylinder exchange program operated by South Western Ontario Propane (SWOP) Inc., was described. The company specializes in propane cylinder exchange and in the refurbishing and marketing of top quality domestic and commercial propane cylinders. The company, currently operating out of Bradford, Ontario, was started in 1991. It employs a staff of 25 in peak season. It has some 200 exchange outlets throughout Ontario and has accepted outdated tanks from as far west as Manitoba and as far east as Quebec. A typical transaction involves bringing an empty cylinder to the nearest SWOP location and exchanging it for a full SWOP cylinder. SWOP does about 50,000 to 60,000 exchanges a year. For the consumer, the program is said to be cheaper, safer and more convenient than getting refills. As far as dealers are concerned operating a SWOP exchange outlet can add extra profits, attract new customers, and build additional consumer loyalty without the need for extra staff or additional indoor space. SWOP delivers full cylinders to exchange outlets on a weekly basis when it also picks up the empty cylinders. At dealer locations, the cylinders (full or empty) are stored in company -designed vandal-proof metal cages. Major expansion of the network of outlets and the cylinder refurbishing and refilling facilities are planned for 1998

  12. Horizontal drilling in shallow reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Murray, W.F. Jr.; Schrider, L.A.; McCallister, J.V.; Mazza, R.L.

    1993-12-31

    Belden & Blake and the US DOE will cofund a horizontal well to be drilled in the Clinton Sandstone as part of the DOE`s multi well program titled ``Horizontal Drilling in Shallow Geologic Complex Reservoirs.`` This well will be located in Mahoning County, Ohio in an area which has demonstrated above average Clinton gas production. To the best of our knowledge, this will be the first horizontal well drilled to the Clinton Sand formation in Ohio. Since many of the remaining Clinton Sand drilling sites are of poorer reservoir quality, they may not be developed unless technology such as horizontal drilling can be successfully demonstrated.

  13. Flow control behind a circular cylinder via a porous cylinder in deep water

    Directory of Open Access Journals (Sweden)

    Akilli H.

    2013-04-01

    Full Text Available In this present work, the effects of surrounding outer porous cylinder on vortex structure downstream of a circular inner cylinder are investigated experimentally in deep water flow. The porosity of outer cylinder were selected as β = 0.4, 0.5, 0.6, 0.65, 0.7, 0.75, 0.8 and 0.85. Porosity is defined as the ratio of the gap area on the body to the whole body surface area. The ratio of outer cylinder diameter to inner cylinder diameter, Do/Di was selected as 2.0, i.e. the inner cylinder diameter is Di = 30 mm where the outer cylinder diameter is Do = 60 mm. All experiments were carried out above a platform. The water height between the base of the platform and the free surface was adjusted as 340 mm. Free stream velocity is U = 156 mm/s, which corresponds to the Reynolds number of Rei = 5,000 based on the inner cylinder diameter. It has been observed that the outer porous cylinders have influence on the attenuation of vortex shedding in the wake region for all porosities. The turbulent intensity of the flow is reduced at least 45% by the presence of outer porous cylinder compared to the bare cylinder case. The porosities β = 0.4 and 0.5 are most suitable cases to control the flow downstream of the circular cylinder.

  14. Hard sphere packings within cylinders.

    Science.gov (United States)

    Fu, Lin; Steinhardt, William; Zhao, Hao; Socolar, Joshua E S; Charbonneau, Patrick

    2016-02-23

    Arrangements of identical hard spheres confined to a cylinder with hard walls have been used to model experimental systems, such as fullerenes in nanotubes and colloidal wire assembly. Finding the densest configurations, called close packings, of hard spheres of diameter σ in a cylinder of diameter D is a purely geometric problem that grows increasingly complex as D/σ increases, and little is thus known about the regime for D > 2.873σ. In this work, we extend the identification of close packings up to D = 4.00σ by adapting Torquato-Jiao's adaptive-shrinking-cell formulation and sequential-linear-programming (SLP) technique. We identify 17 new structures, almost all of them chiral. Beyond D ≈ 2.85σ, most of the structures consist of an outer shell and an inner core that compete for being close packed. In some cases, the shell adopts its own maximum density configuration, and the stacking of core spheres within it is quasiperiodic. In other cases, an interplay between the two components is observed, which may result in simple periodic structures. In yet other cases, the very distinction between the core and shell vanishes, resulting in more exotic packing geometries, including some that are three-dimensional extensions of structures obtained from packing hard disks in a circle. PMID:26843132

  15. Oscillations and translation of a free cylinder in a confined flow

    CERN Document Server

    D'Angelo, Maria Veronica; Auradou, Harold

    2013-01-01

    An oscillatory instability has been observed experimentally on an horizontal cylinder free to move and rotate between two parallel vertical walls of distance H; its characteristics differ both from vortex shedding driven oscillations and from those of tethered cylinders in the same geometry. The vertical motion of the cylinder, its rotation about its axis and its transverse motion across the gap have been investigated as a function of its diameter D, its density s, of the mean vertical velocity U of the fluid and of its viscosity. For a blockage ratio D/H above 0.5 and a Reynolds number Re larger then 14, oscillations of the rolling angle of the cylinder about its axis and of its transverse coordinate in the gap are observed together with periodic variations of the vertical velocity. Their frequency f is the same for the sedimentation of the cylinder in a static fluid (U = 0) and for a non-zero mean flow (U 6= 0). The Strouhal number St associated to the oscillation varies as 1/Re with : St.Re = 3 $\\pm$ 0.15....

  16. Inferring horizontal gene transfer.

    Directory of Open Access Journals (Sweden)

    Matt Ravenhall

    2015-05-01

    Full Text Available Horizontal or Lateral Gene Transfer (HGT or LGT is the transmission of portions of genomic DNA between organisms through a process decoupled from vertical inheritance. In the presence of HGT events, different fragments of the genome are the result of different evolutionary histories. This can therefore complicate the investigations of evolutionary relatedness of lineages and species. Also, as HGT can bring into genomes radically different genotypes from distant lineages, or even new genes bearing new functions, it is a major source of phenotypic innovation and a mechanism of niche adaptation. For example, of particular relevance to human health is the lateral transfer of antibiotic resistance and pathogenicity determinants, leading to the emergence of pathogenic lineages. Computational identification of HGT events relies upon the investigation of sequence composition or evolutionary history of genes. Sequence composition-based ("parametric" methods search for deviations from the genomic average, whereas evolutionary history-based ("phylogenetic" approaches identify genes whose evolutionary history significantly differs from that of the host species. The evaluation and benchmarking of HGT inference methods typically rely upon simulated genomes, for which the true history is known. On real data, different methods tend to infer different HGT events, and as a result it can be difficult to ascertain all but simple and clear-cut HGT events.

  17. Almost horizontal turbulence

    International Nuclear Information System (INIS)

    The paper is published without modifications. Kolmogorov's manuscript was apparently prepared during his participation in one of expeditions of the ship 'D. Mendeleev' to the Atlantic Ocean (1969) or in a circumnavigation of the world (1971) organized by the Institute for Oceanology led at the time by A.S. Monin. As Kolmogorov himself wrote, the choice of the topic was stimulated by observations concerning '...meanders with horizontal sizes of hundreds of kilometers on a flow involving a layer of hundreds of meters, with subsequent disintegration of these meanders into vortices gradually decreasing in size to several kilometers'. In modern terminology, the paper is devoted to the problem of intensive mixing in pycnoclines, that is, thin layers of stratified fluid, caused by internal waves whose frequencies are less than the Brent-Vaeisaelae frequency. Here I would like to note two circumstances. The first is the scientific insight characteristic for Kolmogorov; this very approach was later reflected in numerous publications (see, for instance, the monograph by V.S. Modevich, V.I. Nikulin, and A.G. Stetsenko 'Dynamics of internal mixing in a stratified medium', Institute for Hydromechanics, Academy of Sciences of Ukraine, Naukova Dumka, Kiev 1988). The second, the more significant in my opinion, is the genuine intellectual curiosity and breadth of thought of this great thinker, who studied not only the most abstract mathematical constructions but also got his head out of the clouds with great interest to solve concrete applied problems

  18. Cylinders, multi-cylinders and the induced action of $Aut(F_n)$

    OpenAIRE

    Ibrahim, Fedaa

    2012-01-01

    A cylinder $C^1_u$ is the set of infinite words with fixed prefix $u$. A double-cylinder $C^2_{[1,u]}$ is "the same" for bi-infinite words. We show that for every word $u$ and any automorphism $\\varphi$ of the free group $F$ the image $\\varphi(C^1_u)$ is a finite union of cylinders. The analogous statement is true for double cylinders. We give (a) an algorithm, and (b) a precise formula which allows one to determine this finite union of cylinders.

  19. A Convenient Storage Rack for Graduated Cylinders

    Science.gov (United States)

    Love, Brian

    2004-01-01

    An attempt is made to find a solution to the occasional problem of a need for storing large numbers of graduated cylinders in many teaching and research laboratories. A design, which involves the creation of a series of parallel channels that are used to suspend inverted graduated cylinders by their bases, is proposed.

  20. Simulation of the flow around an upstream transversely oscillating cylinder and a stationary cylinder in tandem

    Science.gov (United States)

    Bao, Sheng; Chen, Sheng; Liu, Zhaohui; Li, Jing; Wang, Hanfeng; Zheng, Chuguang

    2012-02-01

    The flow around a transversely oscillating cylinder in tandem with a stationary cylinder was studied using the lattice Boltzmann method at Re = 100. The influences of spacing, oscillation frequency, and amplitude on the flow field were investigated in detail. It was found that, when the upstream cylinder oscillates with small amplitude, the flow pattern can be changed significantly from that of its fixed counterpart. First, the stagnation region ceases to exist. Second, the transition from the vortex suppression (VS) regime to the vortex formation (VF) regime appears earlier than when both cylinders are fixed. Moreover, the system has a wider frequency range of lock-in for both tandem cylinders in the VS regime, while the locked frequency range is slightly increased in the VF regime. The locked region of the tandem-paired cylinders is only slightly wider than that of a single oscillating cylinder. When the system is unlocked, different responses occur in the wakes of the two cylinders. Analysis of the power spectral of lift forces, lift phase portraits, and vorticity contours shows that the wake is regular under conditions of small spacing and small oscillating amplitude. However, with larger spacing, higher oscillating frequency or larger amplitude, the oscillation is powerful enough to dominate the flow field, inducing chaotic flow. The drag and lift forces of both oscillating and stationary cylinders are also discussed. The results reveal large differences between the case of one oscillating cylinder and that of two stationary tandem cylinders.

  1. Numerical study of an oscillating smaller cylinder in the wake of an upstream larger cylinder

    Science.gov (United States)

    Gao, Yangyang; Yu, Dingyong; Wang, Xikun; Tan, Soon Keat

    2012-06-01

    A numerical study of flow around two tandem cylinders with unequal diameters was carried out. The upstream larger cylinder was fixed and the downstream smaller cylinder was allowed to oscillate in the transverse direction only. Comparisons of the experimental and numerical results were made to investigate the effects of the gap ratio on the maximum vibration amplitude and vortex shedding frequency. The results showed that the vibration response of the smaller cylinder was significantly affected by the presence of the upstream larger cylinder, and resulted in greatly reduced vibration amplitudes. With an increasing gap ratio, the vibration amplitude increased. However, the magnitude was lower than that corresponding to a single cylinder (with the same diameter as that of the downstream smaller cylinder) under the same flow conditions.

  2. Quantum walk on a cylinder

    CERN Document Server

    Bru, Luis A; Di Molfetta, Giuseppe; Pérez, Armando; Roldán, Eugenio; Silva, Fernando

    2016-01-01

    We consider the 2D alternate quantum walk on a cylinder. We concentrate on the study of the motion along the open dimension, in the spirit of looking at the closed coordinate as a small or "hidden" extra dimension. If one starts from localized initial conditions on the lattice, the dynamics of the quantum walk that is obtained after tracing out the small dimension shows the contribution of several components, which can be understood from the study of the dispersion relations for this problem. In fact, these components originate from the contribution of the possible values of the quasi-momentum in the closed dimension. In the continuous space-time limit, the different components manifest as a set of Dirac equations, with each quasi-momentum providing the value of the corresponding mass. We briefly discuss the possible link of these ideas to the simulation of high energy physical theories that include extra dimensions.

  3. Applying the Helmholtz illusion to fashion: horizontal stripes won't make you look fatter.

    Science.gov (United States)

    Thompson, Peter; Mikellidou, Kyriaki

    2011-01-01

    A square composed of horizontal lines appears taller and narrower than an identical square made up of vertical lines. Reporting this illusion, Hermann von Helmholtz noted that such illusions, in which filled space seems to be larger than unfilled space, were common in everyday life, adding the observation that ladies' frocks with horizontal stripes make the figure look taller. As this assertion runs counter to modern popular belief, we have investigated whether vertical or horizontal stripes on clothing should make the wearer appear taller or fatter. We find that a rectangle of vertical stripes needs to be extended by 7.1% vertically to match the height of a square of horizontal stripes and that a rectangle of horizontal stripes must be made 4.5% wider than a square of vertical stripes to match its perceived width. This illusion holds when the horizontal or vertical lines are on the dress of a line drawing of a woman. We have examined the claim that these effects apply only for 2-dimensional figures in an experiment with 3-D cylinders and find no support for the notion that horizontal lines would be 'fattening' on clothes. Significantly, the illusion persists when the horizontal or vertical lines are on pictures of a real half-body mannequin viewed stereoscopically. All the evidence supports Helmholtz's original assertion. PMID:23145226

  4. The Modeling of Flow Around a Cylinder and Scour Hole

    Science.gov (United States)

    Smith, H. D.; Foster, D. L.

    2001-12-01

    The scouring of an erodible bed around a submarine object is a concern for hydraulic and coastal scientists. Our ability to model this process depends on how well we can resolve not only the flow around the obstacle, but the physics of sediment transport. As a first step in addressing this complicated problem, we are performing model-data comparisons of flow around a pipeline during five stages of the scour hole development. Currently, we are using the computational fluid dynamics (CFD) model, FLOW-3D, to simulate the velocity profiles around the pipeline and the scour hole. FLOW-3D has the option of five turbulence models (1-equation turbulent energy, 2-equation k-e, Renormalization-Group, Large Eddy Simulation, and Prandtl Mixing Length), resolves fluid-fluid and fluid-air interfaces, and has variable time steps to assure model stability. The model simulations are modeled after and then compared with laboratory investigations by B.L. Jensen et. al. in 1990 (Journal of Offshore Mechanics and Artic Engineering. Volume 112, pgs. 206-216). In the laboratory experiment, all surfaces were hydraulically smooth, however, adding a small roughness (0.5 mm) to the model was found to give improved correlations. The k-e model shows the highest model-data correlations and the lowest RMS deviations for both horizontal mean velocity and turbulent kinetic energy. Vertical mean velocity values are comparable between the different turbulence models. Model-data comparisons are made for the horizontal and vertical mean velocity profiles, as well as the turbulent kinetic energy profiles at several locations upstream and downstream of the cylinder. Model results are in general good agreement with R-squared correlations as high as 1.0 and RMS deviations as low as 0.24 cm/s. However, the poorest correlations are found in the estimations of the turbulent kinetic energy. The presence of the pipeline results in a 1.4 fold increase in the boundary layer eight cylinder diameters downstream

  5. The horizontal planar structure of kinetic energy in a model vertical-axis wind turbine array

    Science.gov (United States)

    Craig, Anna; Zeller, Robert; Zarama, Francisco; Weitzman, Joel; Dabiri, John; Koseff, Jeffrey

    2013-11-01

    Recent studies have indicated that arrays of vertical axis wind turbines (VAWTs) could potentially harvest significantly more power per unit land area than arrays composed of conventional horizontal axis wind turbines. However, to design VAWT arrays for optimal power conversion, a more comprehensive understanding of inter-turbine energy transfer is needed. In the presented study, a geometrically scaled array of rotating circular cylinders is used to model a VAWT array. The horizontal inter-cylinder mean fluid velocities and Reynolds stresses are measured on several cross-sections using 2D particle image velocimetry in a flume. Two orientations of the array relative to the incoming flow are tested. The results indicate that cylinder rotation drives asymmetric mean flow patterns within and above the array, resulting in non-uniform distributions of turbulent kinetic energy. The variability is observed to be directly related to the ratio of the cylinder rotation speed to the streamwise water velocity. Emphasis is placed on the implications of the asymmetries for power production. Work supported by a Stanford Graduate Fellowship to A.E.C, by funding to J.O.D. from ONR N000141211047 and the Gordon and Betty Moore Foundation through Grant GBMF2645, and by funding from the Environmental Fluid Mechanics Laboratory, Stanford University.

  6. Pool boiling heat transfer of water/ γ-alumina micro-fluids around the horizontal cylinder

    Science.gov (United States)

    Nikkhah, V.; Hormozi, F.

    2016-04-01

    A set of experiments was performed to quantify the pool boiling heat transfer coefficient of water/ γ-alumina micro-fluids at mass concentration ranged from 0.1 to 0.4 % of micro-particles with mean size of 1-2 μm. To stabilize the prepared micro-fluid, pH control, stirring and adding the SDS as a surfactant were carried out. Also, thermal conductivity of micro-fluids are measured using KD2 decagon pro. Results showed that micro-fluids have relatively higher thermal conductivity rather than the base fluids. According to the results, there are two distinguishable heat transfer regions namely natural convection and nucleate boiling regions. Influence of some operating parameters such as heat flux, mass concentration of micro-particles and surface fouling resistance on the pool boiling heat transfer coefficient were experimentally studied and briefly discussed. Results demonstrated a significant deterioration of heat transfer coefficient of micro-fluids in comparison with the base fluid over the extended time (1000 min of operation) in nucleate boiling region, while in natural convection region, enhancement of heat transfer coefficient is registered. According to the results, heat transfer coefficient is strongly controlled by/ γ-alumina concentration due to the deposition of micro-particles on the heating section. Rectilinear changes of scale formation with time in term of fouling resistance were clearly seen at regions, where natural convection is a dominant heat transfer mechanism and also for higher heat fluxes at nucleate boiling heat transfer region.

  7. Expansion of Metallic Cylinders under Explosive Loading

    Directory of Open Access Journals (Sweden)

    M.S. Bola

    1992-07-01

    Full Text Available The behaviour of expanding metallic cylinders under explosive loading was studied. Using ultra high speed photography, the expansion characteristics of aluminium and copper metallic cylinders have been evaluated with different c/m ratio, and by changing the nature of high explosive. The results obtained are comparable to those predicted by the Gurney's energy and momentum balance equations. A cylinder test has been established for comparative to the metal by octol, TNT, PEK-1, baratol and composition B are calculated. The results are in close agreement with those calculated by Kury et al.

  8. A suspended rope wrapped around a cylinder

    International Nuclear Information System (INIS)

    The problem of a suspended rope wrapped around a fixed cylinder is studied. If the suspension force is larger than a certain threshold (which is larger than the weight of the rope), the rope would remain tightly wrapped around the cylinder. For suspension forces smaller than that threshold but larger than another threshold, the rope becomes loose (loses contact with the cylinder) at some points, but still remains at rest. These thresholds are obtained when there is no friction. The system is then analysed also with friction, and the threshold of tight-wrapping is obtained for that case as well. (paper)

  9. Transverse and lateral confinement effects on the oscillations of a free cylinder in a viscous flow

    CERN Document Server

    Gianorio, Luciano; Cachile, Mario; Hulin, Jean-Pierre; Auradou, Harold

    2013-01-01

    The different types of instabilities of free cylinders (diameter $D$, length $L$) have been studied in a viscous flow (velocity $U$) between parallel vertical walls of horizontal width $W$ at a distance $H$: the influence of the confinement parameters $D/H$ and $L/W$ has been investigated. As $D/H$ increases, there is a transition from stable flow to oscillations transverse to the walls and then to a fluttering motion with oscillations of the angle of the axis with respect to the horizontal. The two types of oscillations may be superimposed in the transition domain. The frequency $f$ of the transverse oscillations is independent of the lateral confinement $L/W$ in the range: 0.055 \\le L/W \\le 0.94$ for a given cylinder velocity $V_{cx}$ and increases only weakly with $V_{cx}$. These results are accounted for by assuming a 2D local flow over the cylinder with a characteristic velocity independent of $L/W$ for a given $V_{cx}$ value. The experimental values of $f$ are also independent of the transverse confinem...

  10. Chugging response of submerged cylinder

    International Nuclear Information System (INIS)

    In some boiling water reactor accident scenarios, steam condensation and the subsequent vapor bubble collapse phenomena create travelling pressure transients in the water suppression pool affecting the loading on submerged structures. Due to the nature of the short duration of the pressure pulse no potential flow effect is expected in the pool, therefore the consideration of acoustic effects seems satisfactory. The submerged structures are in majority of cylindrical shape. Therefore, the response of an infinite cylinder will be studied here. The initial assumption is that the pool is of infinite dimensions and filled with inviscid fluid of constant acoustic velocity. The assumption of infinite dimensions for the pool does not affect the maximum pressure on the submerged structure since it is occurring prior to the back scattering of the waves on the finite pool walls for short duration pulses. However, this assumption gives different results for late time history of the pressure. Also, the wave is considered to be plane which results in a good accuracy for structures far from the pressure source. (orig.)

  11. Casimir forces between cylinders at different temperatures

    CERN Document Server

    Golyk, Vladyslav A; Reid, M T Homer; Kardar, Mehran

    2012-01-01

    We study Casimir interactions between cylinders in thermal non-equilibrium, where the objects as well as the environment are held at different temperatures. We provide the general formula for the force, in a one reflection approximation, for cylinders of arbitrary radii and optical properties. As is the case for equilibrium, we find that the force for optically diluted cylinders can be obtained by appropriate summation of the corresponding result for spheres. We find that the non-equilibrium forces are generally larger than their equilibrium counterpart at separations greater than the thermal wavelength. They may also exhibit oscillations as function of separation, leading to stable points of zero net force. These effects are particularly pronounced for thin conducting cylinders (e.g. 40nm diameter nano-wires of tungsten) due to their large emissivity.

  12. Rotating Cylinder Treatment System Demonstration (Presentation)

    Science.gov (United States)

    In August 2008, a rotating cylinder treatment system (RCTSTM) demonstration was conducted near Gladstone, CO. The RCTSTM is a novel technology developed to replace the aeration/oxidation and mixing components of a conventional lime precipitation treatment s...

  13. About the frontal resistance to motion of the cylinder

    Directory of Open Access Journals (Sweden)

    A.D. Girgidov

    2011-01-01

    Full Text Available According to conventional diagram of the flow past cylinder, dissipated power in the part of potential flow, formed by windward side of cylinder is calculated. Comparison of this power with the power, required to overcome the resistance to motion of the cylinder, shows that thin boundary layer in windward side of cylinder forms under Reynolds numbers exceeded 100.

  14. 48 CFR 52.247-66 - Returnable Cylinders.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 2 2010-10-01 2010-10-01 false Returnable Cylinders. 52....247-66 Returnable Cylinders. As prescribed in 47.305-17, insert the following clause: Returnable Cylinders (MAY 1994) (a) Cylinder, referred to in this clause, is a pressure vessel designed for...

  15. Sub-wavelength resonances in polygonal metamaterial cylinders

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Breinbjerg, Olav

    It has been shown that the sub-wavelength resonances of circular MTM cylinders also occur for polygonal MTM cylinders. This is the case for lossless and non-dispersive cylinders as well as lossy and dispersive cylinders. The sub-wavelength resonances are thus not limited to structures of canonical...

  16. From reliable sensors to cylinder intelligence

    OpenAIRE

    Casper, Leo; Loo, Jasper van

    2016-01-01

    Reliability of a piston rod position measurement system is key when applied to large hydraulic cylinders. This and other requirements lead to the development of the CIMS (Cylinder Integrated Measurement System), a contactless and highly accurate system that uses the Hall effect to detect an encoded piston rod. To eliminate deviations caused by mechanical tolerances, temperature and air gap variations etc., the raw signals are filtered and compensated. Its functionality has been extended b...

  17. The Skyrmion on a three--cylinder

    CERN Document Server

    Bratek, Lukasz

    2007-01-01

    We examine the class of static and spherically symmetric finite energy hedgehog solutions in the SU(2) Skyrme Model on a metric three-cylinder. We find the exact analytic shape function of the Skyrmion. It can be expressed via elliptic integrals. We calculate its energy and analyze its stability with respect to radial and spherically symmetric deformations. No other nonconstant solutions belonging to this class are possible on the three-cylinder.

  18. Dynamic Fracture Simulations of Explosively Loaded Cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, Carly W. [Univ. of California, Davis, CA (United States). Dept. of Civil and Environmental Engineering; Goto, D. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-11-30

    This report documents the modeling results of high explosive experiments investigating dynamic fracture of steel (AerMet® 100 alloy) cylinders. The experiments were conducted at Lawrence Livermore National Laboratory (LLNL) during 2007 to 2008 [10]. A principal objective of this study was to gain an understanding of dynamic material failure through the analysis of hydrodynamic computer code simulations. Two-dimensional and three-dimensional computational cylinder models were analyzed using the ALE3D multi-physics computer code.

  19. Local buckling in cylinders with stringer stiffened

    International Nuclear Information System (INIS)

    Some results of a nonlinear analysis of the local elastic stability in uniform axially compressed stringer - stiffened circular cylinders are presented. The possibility to occur bifurcation loads due to anti-symetrical secundary mode are analyzed. The utilization of stringer stiffened as suggested by the ortotropic theory, can lead to the interaction between local and global deformation mode, resulting in primary bifurcation loads lower than the classical critical load of the isotropic cylinder. (E.G.)

  20. Cylinder fragmentation using gas gun techniques

    International Nuclear Information System (INIS)

    In this study an experimental technique for study of cylinder fracture fragmentation characteristics has been developed on a two-stage light gas gun. This test method allows the study of cylinder fracture fragmentation in a laboratory environment under well-controlled loading conditions. Application of this technique allows measure of failure strain, strain rates, expansion velocity, and fragmentation toughness. Results of several experiments on Aermet steel are presented

  1. Optical absorption for parallel cylinder arrays

    OpenAIRE

    Robles, P; Rojas, R.; Claro, F.

    2001-01-01

    We study the long wavelength electromagnetic resonances of interacting cylinder arrays. By using a normal modes expansion where the effects of geometry and material are separated, it is shown that two parallel cylinders with different radii have electromagnetic modes distributed symmetrically about depolarization factor 1/2. Both sets couple to longitudinal and transverse components of the external field, but amplitudes of symmetric depolarization factors become exchanged when considering lon...

  2. Electromagnetic Casimir Forces in Elliptic Cylinder Geometries

    OpenAIRE

    Graham, Noah

    2013-01-01

    The scattering theory approach makes it possible to carry out exact calculations of Casimir energies in any geometry for which the scattering T-matrix and a partial wave expansion of the free Green's function are available. We implement this program for the case of a perfectly conducting elliptic cylinder, thereby completing the set of geometries where electromagnetic scattering is separable. Particular emphasis is placed on the case of zero radius, where the elliptic cylinder reduces to a st...

  3. Do cylinders exhibit a cubatic phase?

    OpenAIRE

    Blaak, R.; Frenkel, D.; Mulder, B.M.

    1999-01-01

    We investigate the possibility that freely rotating cylinders with an aspect ratio L/D = 0.9 exhibit a cubatic phase similar to the one found for a system of cut spheres. We present theoretical arguments why a cubatic phase might occur in this particular system. Monte Carlo simulations do not confirm the existence of a cubatic phase for cylinders. However, they do reveal an unexpected phase behavior between the isotropic and crystalline phase.

  4. Suppression of Brazier Effect in Multilayered Cylinders

    OpenAIRE

    Hiroyuki Shima; Motohiro Sato; Sung-Jin Park

    2014-01-01

    When a straight hollow tube having circular cross-section is bent uniformly into an arc, the cross-section tends to ovalize or flatten due to the in-plane stresses induced by bending; this ovalization phenomenon is called the Brazier effect. The present paper is aimed at theoretical formulation of the Brazier effect observed in multilayered cylinders, in which a set of thin hollow cylinders are stacked concentrically about the common axis. The results indicate that mechanical couplings betwee...

  5. Uranium hexafluoride cylinders survive train derailment

    International Nuclear Information System (INIS)

    A serious train derailment took place in North Carolina in March of 1977. Two of the twenty-nine cars which went off the tracks carried radioactive materials in the form of natural uranium hexafluoride - UF6(N). The packaging for this low specific activity material is a 48 inch diameter by 12.5 foot long cylinder constructed of 5/8 inch thick steel. Each of the four cylinders contained approximately 12,500 kg of UF6(N). The cylinders were mounted on steel cradles which were securely fastened to trailers which in turn were riding on flatcars in standard piggyback fashion. All four of the trailers and cylinders were damaged. The condition of each cylinder immediately after the accident, the recovery and subsequent shipment to Oak Ridge, the receipt inspection and the final disposition of the cylinders and the contents are described in the paper. The immediate response of the media to the news that radioactive material was on the train resulted in a great deal of misinformation being disseminated. In contrast to the initial reports of leakage, there was no breach of the containers and no radioactive contamination of any kind. The National Transportation Safety Board has issued a report on the accident recommending development of guidelines for emergency response procedures

  6. Results of ultrasonic testing evaluations on UF6 storage cylinders

    International Nuclear Information System (INIS)

    The three site cylinder management program is responsible for the safe storage of the DOE owned UF6 storage cylinders at PORTS, PGDP and at the K-25 site. To ensure the safe storage of the UF6 in the cylinders, the structural integrity of the cylinders must be evaluated. This report represents the latest cylinder integrity investigation that utilized wall thickness evaluations to identify thinning due to atmospheric exposure

  7. Simulation of disordered systems of cylinders. II. mechanical behaviour

    OpenAIRE

    Stauffer, D.; Herrmann, H. J.; Roux, S

    1987-01-01

    A model is simulated, with non-linear relaxation methods close to molecular dynamics, describing the mechanical behavior of a random array of hard and soft parallel cylinders. Moreover, the hard cylinders fluctuate slightly in their radii. The relation between compression and force is about the same for the whole system as it is for two cylinders (Hertz law), if only soft cylinders exist. Instead, the radius fluctuations of the hard cylinders produce drastic deviations between the macroscopic...

  8. SECURING INNOVATIVE LEADERSHIP ON THE GAS CYLINDERS MARKET

    OpenAIRE

    Рубан, А. Г.

    2015-01-01

    The article reviews formation and development of the gas cylinders business of «Worthing-ton Cylinders GmbH». It depicts technological process of cylinders manufacturing. The article describes the product range, major types and parameters of the manufactured high pressure cylinders for technical gases, compressed natural gas, and gases of breathing apparatus. It considers competitive advantages of the «Worthington Cylinders GmbH» products and recommendations for its promotion on CIS markets. ...

  9. RESULTS RESULTING FROM AUTOFRETTAGE OF CYLINDER

    Institute of Scientific and Technical Information of China (English)

    ZHU Ruilin

    2008-01-01

    Autofrettage is used to introduce advantageous residual stresses into wall of a cylinder and to even distributions of total stresses. Basic theory on autofrettage has been functioning for several decades. It is necessary to reveal profound relations between parameters in the theory. Therefore, based on the 3rd strength theory, δei/δy, δei/δy, δei′/δy, δei′/δy and their relations, as well as p/δy, are studied under ideal conditions, where δei/δy is equivalent stress of total stresses at elastoplastic juncture/yield strength, δei/δy is equivalent stress of total stresses at inside surface/yield strength, δei′/δy is equivalent stress of residual stresses at elastoplastic juncture/yield strength, δei′/δy is equivalent stress of residual stresses at inside surface/yield strength, p/δy is load-bearing capacity of an autofrettaged cylinder/yield strength. Theoretical study on the parameters results in noticeable results and laws. The main idea is: to satisfy |δei′|=δy, the relation between kj and k is , where k is outside/inside radius ratio of a cylinder, kj is ratio of elastoplastic juncture radius to inside radius of a cylinder; when the plastic region covers the whole wall of a cylinder, for compressive yield not to occur after removing autofrettage pressure, the ultimate k is k=2.218 46, with k=2.218 46, a cylinder's ultimate load-bearing capacity equals its entire yield pressure, or =lnk; when kj≤=1.648 72, no matter how great k is, compressive yield never occurs after removing pa; the maximum and optimum load-bearing capacity of an autofrettaged cylinder is just two times the loading which an unautofrettaged cylinder can bear elastically, or , thus the limit of the load-bearing capacity of an autofrettaged cylinder is also just 2 times that of an unautofrettaged cylinder.

  10. DRILL BITS FOR HORIZONTAL WELLS

    Directory of Open Access Journals (Sweden)

    Paolo Macini

    1996-12-01

    Full Text Available This paper underlines the importance of the correct drill bit application in horizontal wells. Afler the analysis of the peculiarities of horizontal wells and drainholes drilling techniques, advantages and disadvantages of the application of both roller cone and fixed cutters drill bits have been discussed. Also, a review of the potential specific featuries useful for a correct drill bit selection in horizontal small diameter holes has been highlighted. Drill bits for these special applications, whose importance is quickly increasing nowadays, should be characterised by a design capable to deliver a good penetration rate low WOB, and, at the same time, be able to withstand high RPM without premature cutting structure failure and undergauge. Formation properties will also determine the cutting structure type and the eventual specific features for additional gauge and shoulder protection.

  11. Pressure analysis for horizontal wells

    Energy Technology Data Exchange (ETDEWEB)

    Spivak, D.

    1988-01-01

    This study deals with the solution for pressure response of horizontal wells in three different anisotropic media: the infinite reservoir, the limited reservoir and the reservoir with constant pressure at the outer boundaries. Pressure analyses for vertical wells in various reservoirs are abundant, but there has been no comprehensive study of pressure analysis for horizontal wells in these three media. The objectives of this work are to examine and to determine the likely effects of horizontal wells on productivity and on the integration of pressure tests. The method of images, the concept of instantaneous sources and the Newman product method have been used. Integration of the summed source functions is achieved numerically using Simpson's rule. All three solutions are semi-analytical and have been verified and validated. For the infinite reservoir the solution has been compared to a directional well of high angle, and long horizontal well responses have been compared to the solution for the uniform-flux vertical fracture. The solutions to the other two cases (for long horizontal wells) have been compared to published solutions for uniform-flux vertical fractures. New equations, new pseudo-skin factors, new type curves, and new shape factors have been generated in the course of this work. The log-log type curves can be used to determine reservoir characteristics. The influences of different well and reservoir parameters on the well productivity have been investigated and are presented to show the merits of horizontal wells. A major features of this study is that some portions are presented here for the first time.

  12. Oscillatory and Steady Flows in the Annular Fluid Layer inside a Rotating Cylinder

    Directory of Open Access Journals (Sweden)

    Veronika Dyakova

    2016-01-01

    Full Text Available The dynamics of a low-viscosity fluid inside a rapidly rotating horizontal cylinder were experimentally studied. In the rotating frame, the force of gravity induces azimuthal fluid oscillations at a frequency equal to the velocity of the cylinder’s rotation. This flow is responsible for a series of phenomena, such as the onset of centrifugal instability in the Stokes layer and the growth of the relief at the interface between the fluid and the granular medium inside the rotating cylinder. The phase inhomogeneity of the oscillatory fluid flow in the viscous boundary layers near the rigid wall and the free surface generates the azimuthal steady streaming. We studied the relative contribution of the viscous boundary layers in the generation of the steady streaming. It is revealed that the velocity of the steady streaming can be calculated using the velocity of the oscillatory fluid motion.

  13. Die erhöhte horizontal Ebene / Plano horizontal plano

    OpenAIRE

    Campo Baeza, Alberto

    2011-01-01

    Artículo sobre el plano horizontal en arquitectura. Esta investigación se inscribe en la línea "Luz y gravedad". Se relacionan conceptos y obras de la historia de la arquitectura con los conceptos desarrollados en los proyectos de Alberto Campo Baeza. La revista Bauwelt está indexada en AVERY y RIBA.

  14. A laboratory study on sediment resuspension within arrays of rigid cylinders

    Science.gov (United States)

    Tinoco, Rafael O.; Coco, Giovanni

    2016-06-01

    We present results from laboratory experiments on flow through submerged arrays of rigid cylinders embedded in a sandy bed. Using rigid, cylindrical elements to mimic vegetation and benthos, we account for only the physical effects resulting from their presence, eliminating biological factors, such as biofilms and root systems. In line with previous findings, rigid arrays modify the flow mean and turbulent velocity statistics. However, even if the flow speed is significantly damped within dense arrays, the amount of sediment that gets lifted into suspension increases as the density of the array increases due to array- and cylinder-scale turbulence. We present a first attempt to provide predictive relationships of suspended sediment concentration using an alternative approach for the Shields parameter with an empirical coefficient to account for turbulence generated by submerged arrays of rigid cylinders. A similar analysis, using a ratio of populated to non-populated Shields parameter, is conducted to predict resuspension as a function of array density.

  15. On Vertically Global, Horizontally Local Models for Astrophysical Disks

    CERN Document Server

    McNally, Colin P

    2014-01-01

    Barotropic fluids, for which the pressure is only a function of the density, rotate on cylinders in the presence of a gravitational potential, so that the angular frequency of such a disk is independent of height. Therefore the shearing box framework, representing a small disk volume with height-independent angular frequency, can consistently model barotropic disks. If the fluid in the disk is baroclinic, the angular frequency does in general de- pend on height and it is thus necessary to go beyond the standard shearing box approach. In this paper, we show that given a global disk model, it is possible to develop consistent models that are local in horizontal planes and global in height with shearing-periodic boundary conditions. These models can be non-axisymmetric for globally barotropic disks but should be axisymmetric for globally baroclinic disks. We provide explicit equations for this vertically global shearing box which can be implemented in standard magnetohydrodynamic codes by generalizing the sheari...

  16. Wake dynamics behind a seal-vibrissa-shaped cylinder: a comparative study by time-resolved particle velocimetry measurements

    Science.gov (United States)

    Wang, Shaofei; Liu, Yingzheng

    2016-03-01

    The wake dynamics behind a seal-vibrissa-shaped cylinder, which are closely related to the seal's extraordinary ability to faithfully track the hydrodynamic trails of its upstream prey, were extensively studied by using time-resolved particle image velocity. Four cylindrical configurations that shared the same hydrodynamic diameter (i.e., a circular cylinder, an elliptical cylinder, a wavy cylinder, and a vibrissa-shaped cylinder) were chosen for the comparative study at the Reynolds number 1.8 × 103. The instantaneous flow fields behind the cylinders were measured along their vertical and horizontal planes. The distinct global differences between the wakes were determined from the streamline patterns, the reverse-flow intermittences, and both the streamwise and longitudinal velocity fluctuation intensities. Compared to the other three systems tested, the vibrissa-shaped cylinder system was characterized by a considerably reduced recirculation zone in the nodal plane, the existence of a very stably reversed flow, and substantial reductions in the streamwise and longitudinal velocity fluctuation intensities. Further cross-correlation of the fluctuating longitudinal velocities showed that the unsteady events behind the vibrissa-shaped cylinder were poorly organized by sequence and considerably constrained in their spatial extent. Finally, a dynamic mode decomposition (DMD) was performed on the instantaneously varying wake flows. In the wavy cylinder system, a single dominant DMD mode at St = 0.2 (corresponding to Karman vortex street) was detected in both the saddle and nodal planes. Although the dominant DMD modes at St = 0.23 and 0.3 were determined in the saddle and nodal planes of the vibrissa-shaped cylinder system, respectively, the spatial pattern of these two DMD modes showed resolved vortical structures that were highly distorted and constrained to an extremely limited space. These DMD modes had much less energy than those in the other three systems. The

  17. Nonlinear spacing and frequency effects of an oscillating cylinder in the wake of a stationary cylinder

    Science.gov (United States)

    Yang, Xiaofan; Zheng, Zhongquan Charlie

    2010-04-01

    Nonlinear responses to a transversely oscillating cylinder in the wake of a stationary upstream cylinder are studied theoretically by using an immersed-boundary method at Re=100. Response states are investigated in the three flow regimes for a tandem-cylinder system: the "vortex suppression" regime, the critical spacing regime, and the "vortex formation" regime. When the downstream cylinder is forced to oscillate at a fixed frequency and amplitude, the response state of flow around the two cylinders varies with different spacing between the two cylinders, while in the same flow regime, the response state can change with the oscillating frequency and amplitude of the downstream cylinder. Based on velocity phase portraits, each of the nonlinear response states can be categorized into one of the three states in the order of increasing chaotic levels: lock-in, transitional, or quasiperiodic. These states can also be correlated with velocity spectral behaviors. The discussions are conducted using near-wake velocity phase portraits, spectral analyses, and related vorticity fields. A general trend in the bifurcation diagrams of frequency spacing shows the smaller the spacing, frequency, or amplitude, the less chaotic the response state of the system and more likely the downstream and upstream wakes are in the same response state. The system is not locked-in in any case when the spacing between the cylinders is larger than the critical spacing. The near-wake velocity spectral behaviors correspond to the nonlinear response states, with narrow-banded peaks shown at the oscillation frequency and its harmonics in the lock-in cases. High frequency harmonic peaks, caused by interactions between the upstream wake and the downstream oscillating cylinder, are reduced in the near-wake velocity spectra of the upstream cylinder when the spacing increases.

  18. Flexural vibrations of finite composite poroelastic cylinders

    Indian Academy of Sciences (India)

    Sandhya Rani Bandari; Srisailam Aleti; Malla Reddy Perati

    2015-04-01

    This paper deals with the flexural vibrations of composite poroelastic solid cylinder consisting of two cylinders that are bonded end to end. Poroelastic materials of the two cylinders are different. The frequency equations for pervious and impervious surfaces are obtained in the framework of Biot’s theory of wave propagation in poroelastic solids. The gauge invariance property is used to eliminate one arbitrary constant in the solution of the problem. This would lower the number of boundary conditions actually required. If the wavelength is infinite, frequency equations are degenerated as product of two determinants pertaining to extensional vibrations and shear vibrations. In this case, it is seen that the nature of the surface does not have any influence over shear vibrations unlike in the case of extensional vibrations. For illustration purpose, three composite cylinders are considered and then discussed. Of the three, two are sandstone cylinders and the third one is resulted when a cylindrical bone is implanted with Titanium. In either case, phase velocity is computed against aspect ratios.

  19. Prediction of external corrosion for steel cylinders

    International Nuclear Information System (INIS)

    The US Department of Energy (DOE) currently manages the UF6 Cylinder Program (the program). The program was formed to address the depleted-uranium hexafluoride (UF6) stored in approximately 50,000 carbon steel cylinders. The cylinders are located at three DOE sites: the K-25 site (K-25) at Oak Ridge, Tennessee; the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The System Requirements Document (SRD) (LMES 1996a) delineates the requirements of the program. The appropriate actions needed to fulfill these requirements are then specified within the System Engineering Management Plan (SEMP) (LMES 1996b). The report presented herein documents activities that in whole or in part satisfy specific requirements and actions stated in the UF6 Cylinder Program SRD and SEMP with respect to forecasting cylinder conditions. The wall thickness projections made in this report are based on the assumption that the corrosion trends noted will continue. Some activities planned may substantially reduce the rate of corrosion, in which case the results presented here are conservative. The results presented here are intended to supersede those presented previously, as the quality of several of the datasets has improved

  20. UF{sub 6} cylinder fire test

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.H. [Oak Ridge K-25 Site, Oak Ridge, TN (United States)

    1991-12-31

    With the increasing number of nuclear reactors for power generation, there is a comparable increase in the amount of UF{sub 6} being transported. Likewise, the probability of having an accident involving UF{sub 6}-filled cylinders also increases. Accident scenarios which have been difficult to assess are those involving a filled UF{sub 6} cylinder subjected to fire. A study is underway at the Oak Ridge K-25 Site, as part of the US DOE Enrichment Program, to provide empirical data and a computer model that can be used to evaluate various cylinder-in-fire scenarios. It is expected that the results will provide information leading to better handling of possible fire accidents as well as show whether changes should be made to provide different physical protection during shipment. The computer model being developed will be capable of predicting the rupture of various cylinder sizes and designs as well as the amount of UF{sub 6}, its distribution in the cylinder, and the conditions of the fire.

  1. Transition to turbulence in the separated shear layers of yawed circular cylinders

    International Nuclear Information System (INIS)

    Spatial and temporal resolution of transition to turbulence inside the free-shear layers of two yawed circular cylinders is the subject of the present investigation. These physics were resolved using the large-eddy simulation (LES) methodology. An O-type grid was implemented such that the spatial scales of the LES computation fully resolved the energy range physics of the shear layers at Reynolds number ReD = 8000 based on the cylinder diameter. The two test cases modeled the cylinder span skewed at angles 45o and 60o from the horizontal axis. Observations revealed the same transition process as the normal cross-flow state. Soon after separation, Tollmien-Schlichting disturbances were predicted that evolved into Kelvin-Helmholtz (K-H) eddies before absorption by the large-scale Karman-type vortices. These eddies defaulted to a spanwise wavy pattern similar to a normal cross-flow due to their three-dimensional instability. No mixed modes were found between the K-H (Bloor) and Strouhal frequencies. The effect of yaw angle shortened the transition process. As a result, peak turbulence levels inside the wake formation zone approach the downstream cylinder periphery. In addition, the dimensionless frequencies of the K-H eddies lie above the normal cross-flow relationship as formulated by . Disparity between the yawed and normal cross-flow states was further emphasized by the shear-layer transition characteristics. Although each property displayed the expected exponential growth during transition to turbulence, their dimensionless form was miss-aligned with those of the normal cross-flow case. Based on the present evidence, additional simulations (and/or experimental measurements) are necessary to form conclusive arguments regarding the expected behavior of the transition characteristics within the free-shear layers of yawed circular cylinders.

  2. Sky reconstruction for the Tianlai cylinder array

    CERN Document Server

    Zhang, Jiao; Ansari, Reza; Chen, Xuelei; Li, Yichao; Wu, Fengquan; Campagne, Jean-Eric; Magneville, Christophe

    2016-01-01

    In this paper, we apply our sky map reconstruction method for transit type interferometers to the Tianlai cylinder array. The method is based on the spherical harmonic decomposition, and can be applied to cylindrical array as well as dish arrays and we can compute the instrument response, synthesised beam, transfer function and the noise power spectrum. We consider cylinder arrays with feed spacing larger than half wavelength, and as expected, we find that the arrays with regular spacing have grating lobes which produce spurious images in the reconstructed maps. We show that this problem can be overcome, using arrays with different feed spacing on each cylinder. We present the reconstructed maps, and study the performance in terms of noise power spectrum, transfer function and beams for both regular and irregular feed spacing configurations.

  3. Chaotic Rotation of a Towed Elliptical Cylinder

    CERN Document Server

    Weymouth, G D

    2013-01-01

    In this paper I consider the self-excited rotation of an elliptical cylinder towed through a viscous fluid as a canonical model of nonlinear fluid structure interactions with possible applications in the design of sensors and energy extraction devices. Remarkably, it is shown that this system demonstrates chaotic trajectories with only one structural degree of freedom in a two-dimensional laminar flow. First, this self-excited system is shown to be analogous to the forced bistable oscillators studied in classic chaos theory. Next, fully coupled computational fluid dynamics simulations of the motion of the cylinder demonstrate limit cycle, period doubling, intermittently chaotic, and fully chaotic dynamics as the distance between the pivot and the centroid is varied. The viscous wake behind the cylinder is presented for the limit cycle cases and new types of stable wakes are characterized. The wake in the chaotic case demonstrates a strong history effect, with a variety of wake types possible for a given struc...

  4. Corrosion of breached UF6 storage cylinders

    International Nuclear Information System (INIS)

    This paper describes the corrosion processes that occurred following the mechanical failure of two steel 14-ton storage cylinders containing depleted UF6. The failures both were traced to small mechanical tears that occurred during stacking of the cylinders. Although subsequent corrosion processes greatly extended the openings in the wall. the reaction products formed were quite protective and prevented any significant environmental insult or loss of uranium. The relative sizes of the two holes correlated with the relative exposure times that had elapsed from the time of stacking. From the sizes and geometries of the two holes, together with analyses of the reaction products, it was possible to determine the chemical reactions that controlled the corrosion process and to develop a scenario for predicting the rate of hydrolysis of UF6, the loss rate of HF, and chemical attack of a breached UF6 storage cylinder

  5. UF{sub 6} cylinder inspections at PGDP

    Energy Technology Data Exchange (ETDEWEB)

    Lamb, G.W.; Whinnery, W.N. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    Routine inspections of all UF{sub 6} cylinders at the Paducah Gaseous Diffusion Plant have been mandated by the Department of Energy. A specific UF{sub 6} cylinder inspection procedure for what items to inspect and training for the operators prior to inspection duty are described. The layout of the cylinder yards and the forms used in the inspections are shown. The large number of cylinders (>30,000) to inspect and the schedule for completion on the mandated time table are discussed. Results of the inspections and the actions to correct the deficiencies are explained. Future inspections and movement of cylinders for relocation of certain cylinder yards are defined.

  6. Valve studies: Hydrogen fluoride monitoring of UF6 cylinder valves

    International Nuclear Information System (INIS)

    Uranium hexafluoride (UF6) cylinder valves have, like the cylinders, been in use and/or storage for periods ranging from 15 to 44 years. Visual inspection of the cylinders has shown that the extent of corrosion and the overall cylinder condition varies widely throughout the storage yards. One area of concern is the integrity of the cylinder valves. Visual inspection has found deposits which have been identified as radioactive material on or near the valves. These deposits suggest leakage of UF6 and may indicate valve degradation; however, these deposits may simply be residual material from cylinder filling operations

  7. The flow past a cactus-inspired grooved cylinder

    Science.gov (United States)

    El-Makdah, Adnan M.; Oweis, Ghanem F.

    2013-02-01

    The star-shaped cross section of giant cylindrical cactus plants is thought to be aerodynamically favorable for protection against toppling by strong winds. Particle image velocimetry is used to investigate the flow details within the surface grooves and in the immediate wake of a cactus-inspired model cylinder with eight longitudinal grooves, at biologically relevant Reynolds numbers between 50 × 103 and 170 × 103. The wake flow is analyzed and compared to a similarly sized circular cylinder. At the lowest Re tested, the wakes from the two geometries are similar. At higher Re, the cactus wake exhibits superior behavior as seen from the mean and turbulent velocities, suggesting that the flow mechanisms are Re dependent. The flow within the surface grooves reveals counter rotating rollers, while the geometrical ridges act as vortex generators known to help with the surface flow attachment. Lastly, a simplistic analysis is described to recover, qualitatively, certain time-dependent flow features from the randomly acquired PIV realizations.

  8. Preliminary design of twin-cylinder engines

    OpenAIRE

    Louvigny, Yannick

    2008-01-01

    This report deals with the preliminary design of a twin-cylinder engine. The goal of the work is not to make the detailed design of the engine but to draw the main characteristics of each kind of engine and to investigate which configuration of twin-cylinder engine matches in the best way to given requirements. A simple model is developed from the motion equations of the rotating and oscillating parts of piston engine. This model allows calculating the values of the inertia forces and mom...

  9. Electromagnetic Invisibility of Elliptic Cylinder Cloaks

    International Nuclear Information System (INIS)

    Structures with unique electromagnetic properties are designed based on the approach of spatial coordinate transformations of Maxwell's equations. This approach is applied to scheme out invisible elliptic cylinder cloaks, which provide more feasibility for cloaking arbitrarily shaped objects. The transformation expressions for the anisotropic material parameters and the field distribution are derived. The cloaking performances of ideal and lossy elliptic cylinder cloaks are investigated by finite element simulations. It is found that the cloaking performance will degrade in the forward direction with increasing loss. (fundamental areas of phenomenology (including applications))

  10. A Hybrid Approach To Tandem Cylinder Noise

    Science.gov (United States)

    Lockard, David P.

    2004-01-01

    Aeolian tone generation from tandem cylinders is predicted using a hybrid approach. A standard computational fluid dynamics (CFD) code is used to compute the unsteady flow around the cylinders, and the acoustics are calculated using the acoustic analogy. The CFD code is nominally second order in space and time and includes several turbulence models, but the SST k - omega model is used for most of the calculations. Significant variation is observed between laminar and turbulent cases, and with changes in the turbulence model. A two-dimensional implementation of the Ffowcs Williams-Hawkings (FW-H) equation is used to predict the far-field noise.

  11. Effects of vertical shear in modelling horizontal oceanic dispersion

    Science.gov (United States)

    Lanotte, A. S.; Corrado, R.; Palatella, L.; Pizzigalli, C.; Schipa, I.; Santoleri, R.

    2016-02-01

    The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ˜ 1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications.

  12. Horizontal transfer of DNA methylation patterns into bacterial chromosomes.

    Science.gov (United States)

    Shin, Jung-Eun; Lin, Chris; Lim, Han N

    2016-05-19

    Horizontal gene transfer (HGT) is the non-inherited acquisition of novel DNA sequences. HGT is common and important in bacteria because it enables the rapid generation of new phenotypes such as antibiotic resistance. Here we show that in vivo and in vitro DNA methylation patterns can be horizontally transferred into bacterial chromosomes to program cell phenotypes. The experiments were performed using a synthetic system in Escherichia coli where different DNA methylation patterns within the cis-regulatory sequence of the agn43 gene turn on or off a fluorescent reporter (CFP). With this system we demonstrated that DNA methylation patterns not only accompany the horizontal transfer of genes into the bacterial cytoplasm but can be transferred into chromosomes by: (i) bacteriophage P1 transduction; and (ii) transformation of extracellular synthetic DNA. We also modified the experimental system by replacing CFP with the SgrS small RNA, which regulates glucose and methyl α-D-glucoside uptake, and showed that horizontally acquired DNA methylation patterns can increase or decrease cell fitness. That is, horizontally acquired DNA methylation patterns can result in the selection for and against cells that have HGT. Findings from these proof-of-concept experiments have applications in synthetic biology and potentially broad implications for bacterial adaptation and evolution. PMID:27084942

  13. Orphan penumbrae: Submerging horizontal fields

    CERN Document Server

    Jurcak, J; Sobotka, M

    2014-01-01

    We investigate the properties of orphan penumbrae, which are photospheric filamentary structures observed in active regions near polarity inversion lines that resemble the penumbra of regular sunspots but are not connected to any umbra. We use Hinode data from the Solar Optical Telescope to determine the properties of orphan penumbrae. Spectropolarimetric data are employed to obtain the vector magnetic field and line-of-sight velocities in the photosphere. Magnetograms are used to study the overall evolution of these structures, and G-band and Ca II H filtergrams are to investigate their brightness and apparent horizontal motions. Orphan penumbrae form between regions of opposite polarity in places with horizontal magnetic fields. Their magnetic configuration is that of $\\Omega$-shaped flux ropes. In the two cases studied here, the opposite-polarity regions approach each other with time and the whole structure submerges as the penumbral filaments disappear. Orphan penumbrae are very similar to regular penumbr...

  14. Horizontal gene transfer in fungi

    OpenAIRE

    Fitzpatrick, David A.

    2011-01-01

    Horizontal gene transfer (HGT) is frequently observed in prokaryotes and until recently was assumed to be of limited importance to eukaryotes. However, there is an increasing body of evidence to suggest that HGT is an important mechanism in eukaryotic genome evolution, particularly in unicellular organisms. The transfer of individual genes, gene clusters or entire chromosomes can have significant impacts on niche specification, disease emergence or shift in metabolic capabil...

  15. Horizontal mergers and product quality

    OpenAIRE

    Brekke, Kurt Richard; Siciliani, Luigi; Straume, Odd Rune

    2014-01-01

    Using a spatial competition framework with three ex ante identical firms, we study the effects of a horizontal merger on quality, price and welfare. The merging firms always reduce quality. They also increase prices if demand responsiveness to quality is sufficiently low. The non-merging firm, on the other hand, always responds by increasing both quality and prices. Overall, a merger leads to higher average prices and quality in the market. The welfare implications of a merger are not clea...

  16. Horizontally oriented plates in clouds

    CERN Document Server

    Bréon, François-Marie

    2011-01-01

    Horizontally oriented plates in clouds generate a sharp specular reflectance signal in the glint direction, often referred to as "subsun". This signal (amplitude and width) may be used to analyze the relative area fraction of oriented plates in the cloud top layer and their characteristic tilt angle to the horizontal. We make use of spaceborne measurements from the POLDER instrument to provide a statistical analysis of these parameters. More than half of the clouds show a detectable maximum reflectance in the glint direction, although this maximum may be rather faint. The typical effective fraction (area weighted) of oriented plates in clouds lies between 10-3 and 10-2. For those oriented plates, the characteristic tilt angle is less than 1 degree in most cases. These low fractions imply that the impact of oriented plates on the cloud albedo is insignificant. The largest proportion of clouds with horizontally oriented plates is found in the range 500-700 hPa, in agreement with typical in situ observation of p...

  17. Breached cylinder incident at the Portsmouth gaseous diffusion plant

    Energy Technology Data Exchange (ETDEWEB)

    Boelens, R.A. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

    1991-12-31

    On June 16, 1990, during an inspection of valves on partially depleted product storage cylinders, a 14-ton partially depleted product cylinder was discovered breached. The cylinder had been placed in long-term storage in 1977 on the top row of Portsmouth`s (two rows high) storage area. The breach was observed when an inspector noticed a pile of green material along side of the cylinder. The breach was estimated to be approximately 8- inches wide and 16-inches long, and ran under the first stiffening ring of the cylinder. During the continuing inspection of the storage area, a second 14-ton product cylinder was discovered breached. This cylinder was stacked on the bottom row in the storage area in 1986. This breach was also located adjacent to a stiffening ring. This paper will discuss the contributing factors of the breaching of the cylinders, the immediate response, subsequent actions in support of the investigation, and corrective actions.

  18. Rigid affine surfaces with isomorphic A2-cylinders

    OpenAIRE

    Dubouloz, Adrien

    2015-01-01

    We construct families of smooth affine surfaces with pairwise non isomorphic A 1-cylinders but whose A 2-cylinders are all isomorphic. These arise as complements of cuspidal hyperplane sections of smooth projective cubic surfaces.

  19. Melting of a phase change material in a horizontal annulus with discrete heat sources

    Directory of Open Access Journals (Sweden)

    Mirzaei Hooshyar

    2015-01-01

    Full Text Available Phase change materials have found many industrial applications such as cooling of electronic devices and thermal energy storage. This paper investigates numerically the melting process of a phase change material in a two-dimensional horizontal annulus with different arrangements of two discrete heat sources. The sources are positioned on the inner cylinder of the annulus and assumed as constant-temperature boundary conditions. The remaining portion of the inner cylinder wall as well as the outer cylinder wall is considered to be insulated. The emphasis is mainly on the effects of the arrangement of the heat source pair on the fluid flow and heat transfer features. The governing equations are solved on a non-uniform O type mesh using a pressure-based finite volume method with an enthalpy porosity technique to trace the solid and liquid interface. The results are obtained at Ra=104 and presented in terms of streamlines, isotherms, melting phase front, liquid fraction and dimensionless heat flux. It is observed that, depending on the arrangement of heat sources, the liquid fraction increases both linearly and non-linearly with time but will slow down at the end of the melting process. It can also be concluded that proper arrangement of discrete heat sources has the great potential in improving the energy storage system. For instance, the arrangement C3 where the heat sources are located on the bottom part of the inner cylinder wall can expedite the melting process as compared to the other arrangements.

  20. Acoustic identification of a poroelastic cylinder

    CERN Document Server

    Fellah, Z; Ogam, E; Scotti, T; Wirgin, A; Fellah, Zine; Groby, Jean-Philippe; Ogam, Erick; Scotti, Thierry; Wirgin, Armand

    2005-01-01

    We show how to cope with the acoustic identification of poroelastic materials when the specimen is in the form of a cylinder. We apply our formulation, based on the Biot model, approximated by the equivalent elastic solid model, to a long bone-like or borehole sample specimen probed by low frequency sound.

  1. Acoustic signal analysis of underwater elastic cylinder

    Institute of Scientific and Technical Information of China (English)

    LI Xiukun; YANG Shi'e

    2001-01-01

    The echoes of underwater elastic cylinder comprise two types of acoustic components: Geometrical scattering waves and elastic scattering waves. The transfer function is appropriate to characterize the echo of targets. And the discrete wavelet transform of amplitude spectrum is presented and used to identify the resonant components of underwater targets.PACS numbers: 43.30, 43.60

  2. The Experience Cylinder, an immersive interactive platform

    DEFF Research Database (Denmark)

    Andreasen, Troels; Gallagher, John Patrick; Møbius, Nikolaj;

    2011-01-01

    This paper describes the development of an experimental interactive installation, a so-called "experience cylinder", intended as a travelogue and developed specifically to provide a narrative about the Viking ship Sea Stallion’s (Havhingst) voyage from Roskilde to Dublin and back. The installatio...

  3. Mechanical Cushion Design Influence on Cylinder Dynamics

    DEFF Research Database (Denmark)

    Borghi, Massimo; Milani, Massimo; Conrad, Finn

    . experimental comparison, involving the piston velocity and the cylinder chambers pressure. After, with the aim of highlighting the effect of mechanical cushions design on a two effect linear actuator dynamic performances, the characteristics modulation of four alternative cushioning systems are determined and...

  4. Effect of Surface Coatings on Cylinders Exposed to Underwater Shock

    OpenAIRE

    Kwon, Y.W.; J.K. Bergersen; Shin, Y.S.

    1994-01-01

    The response of a coated cylinder (metallic cylinder coated with a rubber material) subjected to an underwater explosion is analyzed numerically. The dynamic response of the coated cylinder appears to be adversely affected when impacted by an underwater shock wave under certain conditions of geometry and material properties of the coating. When adversely affected, significant deviations in values of axial stress, hoop stress, and strain are observed. The coated cylinder exhibits a larger defo...

  5. Effect of surface coating on cylinders subjected to underwater shock

    OpenAIRE

    Bergersen, John K.

    1992-01-01

    Approved for public release, distribution unlimited The response of a composite cylinder (metallic cylinder coated with a rubber material) subjected to an underwater explosion was analyzed numerically. Qualitative differences between coated and uncoated cylinders were investigated. The dynamic response of the coated cylinder was found to be adversely affected when impacted by an underwater shock wave under certain conditions of geometry and material properties of the coating. When adversel...

  6. Streamwise forced oscillations of circular and square cylinders

    OpenAIRE

    Tudball-Smith, Daniel; Leontini, Justin S.; Sheridan, John; Lo Jacono, David

    2012-01-01

    International audience The modification of a cylinder wake by streamwise oscillation of the cylinder at the vortex shedding frequency of the unperturbed cylinder is reported. Recent numerical simulations [J. S. Leontini, D. Lo Jacono, and M. C. Thompson, "A numerical study of an inline oscillating cylinder in a free stream," J. Fluid Mech. 688, 551-568 (2011)] showed that this forcing results in the primary frequency decreasing proportionally to the square of the forcing amplitude, before ...

  7. Sub-wavelength resonances in polygonal metamaterial cylinders

    OpenAIRE

    Arslanagic, Samel; Breinbjerg, Olav

    2008-01-01

    It has been shown that the sub-wavelength resonances of circular MTM cylinders also occur for polygonal MTM cylinders. This is the case for lossless and non-dispersive cylinders as well as lossy and dispersive cylinders. The sub-wavelength resonances are thus not limited to structures of canonical shapes but occurs also for other shapes and they are determined more by the material parameters than the geometrical parameters.

  8. Analysis of fatigue life for tube trailer cylinders

    OpenAIRE

    Xinqi YU; Bolong SONG; Zhang, Zhao; Qinggang LIU

    2015-01-01

    Risk of fatigue failure exists in the tube trailer cylinders under the condition of internal pressure variation and inertial load caused through road transport. In order to estimate the safety state of the cylinders under the action of alternating load, the model of certain geometry sizes is built based on the widely used tube trailer cylinders. The fatigue analysis of tube trailer gas cylinders is made aiming at the action of the internal pressure and the inertial load. The fatigue life dist...

  9. Efficient analytical solutions for heated, pressurized multi-layered cylinders

    OpenAIRE

    2013-01-01

    Two independent sets of analytical solutions, one based on matrix inversion and one based on iteration, are derived for the displacement field and corresponding stress state in multi-layer cylinders subjected to pressure and thermal loading. Solutions are developed for cylinders that are axially free with no friction between layers (plane stress), for cylinders that are fully restrained axially (plane strain) and for axially loaded and spring-mounted cylinders, assuming that the combined two-...

  10. 76 FR 33023 - Safety Advisory; Unauthorized Marking of Compressed Gas Cylinders

    Science.gov (United States)

    2011-06-07

    ... Gas Cylinders AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA), DOT. ACTION... undetermined number of certain (aluminum) cylinders were improperly marked and represented as DOT specification 3AL cylinders. The cylinders were neither marked nor certified by an authorized independent...

  11. Failure of Non-Circular Composite Cylinders

    Science.gov (United States)

    Hyer, M. W.

    2004-01-01

    In this study, a progressive failure analysis is used to investigate leakage in internally pressurized non-circular composite cylinders. This type of approach accounts for the localized loss of stiffness when material failure occurs at some location in a structure by degrading the local material elastic properties by a certain factor. The manner in which this degradation of material properties takes place depends on the failure modes, which are determined by the application of a failure criterion. The finite-element code STAGS, which has the capability to perform progressive failure analysis using different degradation schemes and failure criteria, is utilized to analyze laboratory scale, graphite-epoxy, elliptical cylinders with quasi-isotropic, circumferentially-stiff, and axially-stiff material orthotropies. The results are divided into two parts. The first part shows that leakage, which is assumed to develop if there is material failure in every layer at some axial and circumferential location within the cylinder, does not occur without failure of fibers. Moreover before fibers begin to fail, only matrix tensile failures, or matrix cracking, takes place, and at least one layer in all three cylinders studied remain uncracked, preventing the formation of a leakage path. That determination is corroborated by the use of different degradation schemes and various failure criteria. Among the degradation schemes investigated are the degradation of different engineering properties, the use of various degradation factors, the recursive or non-recursive degradation of the engineering properties, and the degradation of material properties using different computational approaches. The failure criteria used in the analysis include the noninteractive maximum stress criterion and the interactive Hashin and Tsai-Wu criteria. The second part of the results shows that leakage occurs due to a combination of matrix tensile and compressive, fiber tensile and compressive, and inplane

  12. Nonlinear bending and collapse analysis of a poked cylinder and other point-loaded cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Sobel, L.H.

    1983-06-01

    This paper analyzes the geometrically nonlinear bending and collapse behavior of an elastic, simply supported cylindrical shell subjected to an inward-directed point load applied at midlength. The large displacement analysis results for this thin (R/t = 638) poked cylinder were obtained from the STAGSC-1 finite element computer program. STAGSC-1 results are also presented for two other point-loaded shell problems: a pinched cylinder (R/t = 100), and a venetian blind (R/t = 250).

  13. Nonlinear bending and collapse analysis of a poked cylinder and other point-loaded cylinders

    International Nuclear Information System (INIS)

    This paper analyzes the geometrically nonlinear bending and collapse behavior of an elastic, simply supported cylindrical shell subjected to an inward-directed point load applied at midlength. The large displacement analysis results for this thin (R/t = 638) poked cylinder were obtained from the STAGSC-1 finite element computer program. STAGSC-1 results are also presented for two other point-loaded shell problems: a pinched cylinder (R/t = 100), and a venetian blind (R/t = 250)

  14. Cylinder Imbalance Detection of Six Cylinder DI Diesel Engine Using Pressure Variation

    OpenAIRE

    S. H. Gawande; L. G. Navale; M. R. Nandgaonkar; D. S. Butala; S. Kunamalla

    2010-01-01

    In this research paper a simplified methodology is presented to detect cylinder imbalance in operating sixcylinder DI diesel engine. The detailed torsional vibration analysis helps to find vibratory frequencies, mode shapes, and vibratory stresses to provide constraints on critical speed in operating engine. The crank shaft is considered to be a rigid body so that the variation of the angular speed could be directly correlated to the cylinder pressure. Actuallythe variation of crank shaft spe...

  15. Evaluation of Cylinder Volume Estimation Methods for In–Cylinder Pressure Trace Analysis

    OpenAIRE

    Adrian Irimescu

    2012-01-01

    In–cylinder pressure trace analysis is an important investigation tool frequently employed in the study of internal combustion engines. While technical data is usually available for experimental engines, in some cases measurements are performed on automotive engines for which only the most basic geometry features are available. Therefore, several authors aimed to determine the cylinder volume and length of the connecting rod by other methods than direct measurement. This stu...

  16. Explicit horizontal open books on some plumbings

    OpenAIRE

    Etgü, Tolga; Ozbagci, Burak

    2005-01-01

    We describe explicit open books on arbitrary plumbings of oriented circle bundles over closed oriented surfaces. We show that, for a non-positive plumbing, the open book we construct is horizontal and the corresponding compatible contact structure is also horizontal and Stein fillable. In particular, we describe horizontal open books on some Seifert fibered 3--manifolds. As another application we describe horizontal open books isomorphic to Milnor open books for some complex surface singulari...

  17. Horizontal well length optimization considering wellbore hydraulics

    OpenAIRE

    Syed, Adnan

    2014-01-01

    Horizontal wells covering entire length of the reservoirs are not economically suitable. Frictional pressure drops increases with the increase in well length and flow rates. Optimal Horizontal length is estimated through economic analysis i.e. Net present Value of the project (NPV). Well construction costs including incremental costs of drilling horizontal section, friction losses in horizontal section, Hydrocarbon prices and Drainage area affect NPV. This thesis work estimates NPV and Produc...

  18. Image analysis of moving seeds in an indented cylinder

    DEFF Research Database (Denmark)

    Buus, Ole; Jørgensen, Johannes Ravn

    2010-01-01

    inspection in seed cleaning equipment. A prototype of an indented cylinder will be constructed. To make it more dynamic, the cylinder itself will be manufactured using 3D printing technology. The input will come either from 3D scans of existing cylinders or by defining their topology using parametric B...

  19. The new six-cylinder motorcycle engine from BMW

    Energy Technology Data Exchange (ETDEWEB)

    Mattes, Wolfgang; Hege, Heinz; Haimerl, Michael; Unterweger, Georg [BMW Motorrad, Muenchen (Germany)

    2011-06-15

    For the first time ever BMW uses a six-cylinder engine for a motorcycle. For the new K1600GT and K1600GTL BMW Motorrad has developed a six-cylinder inline engine, which exceeds a four-cylinder especially under the aspect of engine smoothness and concurrently acts on the same level of fuel consumption. (orig.)

  20. Electromagnetic Wave Scattering By the Coated Impedance Cylinder

    Directory of Open Access Journals (Sweden)

    V.I. Vyunnik

    2010-01-01

    Full Text Available In this work the boundary conditions for the impedance circular cylinder coated by a low contrast dielectric thin layer are derived. Expression for the reduced impedance of the cylinder is obtained. Conditions and applicability limits of the proposed approach are defined. Influence of the coating impedance on the reduced impedance of the cylinder is investigated.

  1. 30 CFR 56.4601 - Oxygen cylinder storage.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Oxygen cylinder storage. 56.4601 Section 56.4601 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Control Welding/cutting/compressed Gases § 56.4601 Oxygen cylinder storage. Oxygen cylinders shall not...

  2. 30 CFR 57.4601 - Oxygen cylinder storage.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Oxygen cylinder storage. 57.4601 Section 57.4601 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... and Control Welding/cutting/compressed Gases § 57.4601 Oxygen cylinder storage. Oxygen cylinders...

  3. Electromagnetic Fields at the Surface of Human-Body Cylinders

    DEFF Research Database (Denmark)

    Kammersgaard, Nikolaj Peter Iversen; Kvist, Søren H.; Thaysen, Jesper; Jakobsen, Kaj Bjarne

    The electromagnetic fields around an infinitely long cylinder with different material parameters are analyzed. The cylinder is modeled as muscle, skin, fat, and perfect electric conductor respectively. The cylinder is illuminated by a plane wave incident from different angles and with both transv...

  4. 49 CFR 178.35 - General requirements for specification cylinders.

    Science.gov (United States)

    2010-10-01

    ... check analysis of a sample from each coil, sheet, or tube. (3) Verify compliance of cylinders with the... taken from welded cylinders are depicted in Figures 1 through 5 in Appendix C to this subpart for the... finished cylinder has been welded by the spinning process, or effected by plugging. (ii) As prescribed...

  5. 30 CFR 56.16005 - Securing gas cylinders.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Securing gas cylinders. 56.16005 Section 56.16005 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... and Handling § 56.16005 Securing gas cylinders. Compressed and liquid gas cylinders shall be...

  6. 30 CFR 57.16005 - Securing gas cylinders.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Securing gas cylinders. 57.16005 Section 57.16005 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Storage and Handling § 57.16005 Securing gas cylinders. Compressed and liquid gas cylinders shall...

  7. Sub-wavelength metamaterial cylinders with multiple dipole resonances

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Breinbjerg, Olav

    2009-01-01

    It has been shown that the sub-wavelength resonances of the individual MTM cylinders also occur for electrically small configurations combining 2 or 4 cylinders. For the 2-and 4-cylinder configurations the overall size is 1/20 and 1/12.5 of the smallest wavelength, respectively. These MTM...

  8. 49 CFR 176.92 - Cylinders laden in vehicles.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Cylinders laden in vehicles. 176.92 Section 176.92 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY... § 176.92 Cylinders laden in vehicles. Any cylinder of Class 2 (compressed gas) material which...

  9. 49 CFR 174.201 - Class 2 (gases) material cylinders.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Class 2 (gases) material cylinders. 174.201... RAIL Detailed Requirements for Class 2 (Gases) Materials § 174.201 Class 2 (gases) material cylinders. (a) Except as provided in paragraphs (b) and (c) of this section, cylinders containing Class 2...

  10. 48 CFR 47.305-17 - Returnable cylinders.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Returnable cylinders. 47... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-17 Returnable cylinders. The contracting officer shall insert the clause at 52.247-66, Returnable Cylinders, in a solicitation and...

  11. Theoretical and experimental stress analyses of ORNL thin-shell cylinder-to-cylinder model 2

    International Nuclear Information System (INIS)

    Model 2 in a series of four thin-shell cylinder-to-cylinder models was tested, and the experimentally determined elastic stress distributions were compared with theoretical predictions obtained from a thin-shell finite-element analysis. Both the cylinder and the nozzle of model 2 had outside diameters of 10 in., giving a d0/D0 ratio of 1.0, and both had outside diameter/thickness ratios of 100. Sixteen separate loading cases in which one end of the cylinder was rigidly held were analyzed. An internal pressure loading, three mutually perpendicular force components, and three mutually perpendicular moment components were individually applied at the free end of the cylinder and at the end of the nozzle. In addition to these 13 loadings, 3 additional loads were applied to the nozzle (in-plane bending moment, out-of-plane bending moment, and axial force) with the free end of the cylinder restrained. The experimental stress distributions for each of the 16 loadings were obtained using 152 three-gage strain rosettes located on the inner and outer surfaces. All the 16 loading cases were also analyzed theoretically using a finite-element shell analysis. The analysis used flat-plate elements and considered five degrees of freedom per node in the final assembled equations. The comparisons between theory and experiment show reasonably good general agreement, and it is felt that the analysis would be satisfactory for most engineering purposes. (auth)

  12. A remark on the computation of shear-horizontal and torsional modes in elastic waveguides.

    Science.gov (United States)

    Gravenkamp, Hauke

    2016-07-01

    When modeling the propagation of elastic guided waves in plates or cylinders, Finite Element based numerical methods such as the Scaled Boundary Finite Element Method (SBFEM) or the Semi-Analytical Finite Element (SAFE) Method lead to an eigenvalue problem to be solved at each frequency. For the particular case of shear horizontal modes in a homogeneous plate or torsional modes in a homogeneous cylinder, the problem can be drastically simplified. The eigenvalues become simple functions of the frequency, while the eigenvectors are constant. The current contribution discusses how this behavior is represented in the numerical formulation and derives the expressions for the eigenvalues and eigenvectors as well as the dynamic stiffness matrix of infinite elastic waveguides. PMID:27014855

  13. Bifurcation phenomena in thermal convection in horizontal, concentric annuli containing saturated porous media

    International Nuclear Information System (INIS)

    A saturated porous medium confined between two horizontal cylinders is considered. As a result of a temperature difference between the cylinders, thermal convection is induced in the medium. The fluid motion is described by the 2-D Darcy-Oberbeck-Boussinesq's (DOB) equations, which the authors' solve using regular perturbation expansion. The steady state problem is solved using Newton's technique. At each step the determinant of the Jacobian is evaluated. Bifurcation points are identified with singularities of the Jacobian. Linear stability analysis is used to determine the stability of various solution branches. The results they obtained from solving the DOB equations using perturbations expansion are compared with those they obtained from solving the nonlinear PDE's numerically and are found to favorably agree

  14. Bubble shape in horizontal and near horizontal intermittent flow

    International Nuclear Information System (INIS)

    Highlights: • The bubble shapes in intermittent flows are presented experimentally. • The nose-tail inversion phenomenon appears at a low Froude number in downward pipe. • Transition from plug to slug flow occurs when the bubble tail changes from staircase pattern to hydraulic jump. - Abstract: This paper presents an experimental study of the shape of isolated bubbles in horizontal and near horizontal intermittent flows. It is found that the shapes of the nose and body of bubble depend on the Froude number defined by gas/liquid mixture velocity in a pipe, whereas the shape of the back of bubble region depends on both the Froude number and bubble length. The photographic studies show that the transition from plug to slug flow occurs when the back of the bubble changes from staircase pattern to hydraulic jump with the increase of the Froude number and bubble length. The effect of pipe inclination on characteristics of bubble is significant: The bubble is inversely located in a downwardly inclined pipe when the Froude number is low, and the transition from plug flow to slug flow in an upward inclined pipe is more ready to occur compared with that in a downwardly inclined pipe

  15. Effects of Variable Valve Lift on In-Cylinder Air Motion

    Directory of Open Access Journals (Sweden)

    Tianyou Wang

    2015-12-01

    Full Text Available An investigation into in-cylinder swirl and tumble flow characteristics with reduced maximum valve lifts (MVL is presented. The experimental work was conducted in the modified four-valve optical spark-ignition (SI test engine with three different MVL. Particle image velocimetry (PIV was employed for measuring in-cylinder air motion and measurement results were analyzed for examining flow field, swirl and tumble ratio variation and fluctuating kinetic energy distribution. Results of ensemble-averaged flow fields show that reduced MVL could produce strong swirl flow velocity, then resulted in very regular swirl motion in the late stage of the intake process. The strong swirl flow can maintain very well until the late compression stage. The reduction of MVL can also increase both high-frequency and low-frequency swirl flow fluctuating kinetic energy remarkably. Regarding tumble flow, results demonstrate that lower MVLs result in more horizontal intake flow velocity vectors which can be easily detected under the valve seat area. Although the result of lower MVLs show a higher tumble ratio when the piston is close to the bottom dead centre (BDC, higher MVLs substantially produce higher tumble ratios which can be confirmed when most cylinder area lies in the measuring range.

  16. An experimental investigation of one-and two-degree of freedom VIV of cylinders

    Institute of Scientific and Technical Information of China (English)

    Zhuang Kang; Lu-Sheng Jia

    2013-01-01

    In the paper,an experiment investigation was conducted for one-and two-degree of freedom vortex-induced vibration (VIV) of a horizontally-oriented cylinder with diameter of 1 1 cm and length of 120 cm.In the experiment,the spring constants in the cross-flow and in-line flow directions were regulated to change the natural vibration frequency of the model system.It was found that,in the one-degree of freedom VIV experiment,a “double peak” phenomenon was observed in its amplitude within the range of the reduced velocities tested,moreover,a “2T” wake appeared in the vicinity of the second peak.In the two-degree of freedom VIV experiment,the trajectory of cylinder exhibited a reverse “C” shape,i.e.,a “new moon” shape.Through analysis of these data,it appears that,besides the non-dimensional in-line and cross-flow natural vibration frequency ratios,the absolute value of the natural vibration frequency of cylinder is also one of the important parameters affecting its VIV behavior.

  17. Experimental investigation on flow-induced vibration excitation in an elastically mounted circular cylinder in cylinder arrays

    International Nuclear Information System (INIS)

    An experimental investigation was performed in a low-speed wind tunnel in which an elastically mounted circular cylinder was fitted with two accelerometers and surrounded by from one to six identical cylinders in order to study the fluid flow characteristics and predict the possibility of suppressing flow-induced vibration excitation in the test cylinder. The spectral diagram, amplitude and orbital motion of the test cylinder were used to analyze the vibration excitation under differing free stream velocities, natural frequencies of the test cylinder, and number of surrounding cylinders. In this study, for the test cylinder with the same natural frequency as the adjacent cylinders (24 Hz) the amplitude response showed that when the fluid flow velocity exceeded a critical value, which depends on the arrangement of the cylinders, fluid elastic instability occurred. Beyond the critical velocity the cylinder became excited and vibrated in a figure-of-eight pattern along with the line-dominated spectrum, which implies that by having the same frequency along with a phase shift, the characteristic behavior of the cylinder is observed to be like an oscillator with the cross-wise and stream-wise response. From the assessment of the amplitude response of the test cylinder it was observed that the upstream cylinders had a greater influence on the amplitude response than the downstream cylinders. On the other hand, when the test cylinder had a natural frequency different to the adjacent cylinders it was observed that the frequency had a minimal effect on the critical velocity, and yet beyond the critical velocity it had a significant influence on the vibration amplitude response. (paper)

  18. Environmental restoration using horizontal wells

    International Nuclear Information System (INIS)

    This paper reports that under sponsorship from the U.S. Department of Energy, technical personnel from the Savannah River Laboratory and other DOE laboratories, universities and private industry have completed a full scale demonstration of environmental remediation using horizontal wells. The test successfully removed approximately 7250 kg of contaminants. A large amount of characterization and monitoring data was collected to aid in interpretation of the test and to provide the information needed for future environmental restorations that employ directionally drilled wells as extraction or delivery systems

  19. Numerical Simulations of Viscous Flow Around Stepped Circular Cylinder

    OpenAIRE

    Bjørkli, Rune

    2012-01-01

    A stepped cylinder could be a desired design for an offshore buoy or SPAR platform. The geometry of a stepped cylinder consists of a small diameter cylinder (d) placed on top of a large diameter cylinder (D). This master thesis has investigated numerically the flow around a stepped cylinder with different diameter ratios (d/D) for a Reynolds number, ReD = 150. The commercial software Fluent v13.0 by Ansys was used for the numerical investigation.The aim of the study has been exploring the nea...

  20. Horizontal gene transfer in chromalveolates

    Directory of Open Access Journals (Sweden)

    Bhattacharya Debashish

    2007-09-01

    Full Text Available Abstract Background Horizontal gene transfer (HGT, the non-genealogical transfer of genetic material between different organisms, is considered a potentially important mechanism of genome evolution in eukaryotes. Using phylogenomic analyses of expressed sequence tag (EST data generated from a clonal cell line of a free living dinoflagellate alga Karenia brevis, we investigated the impact of HGT on genome evolution in unicellular chromalveolate protists. Results We identified 16 proteins that have originated in chromalveolates through ancient HGTs before the divergence of the genera Karenia and Karlodinium and one protein that was derived through a more recent HGT. Detailed analysis of the phylogeny and distribution of identified proteins demonstrates that eight have resulted from independent HGTs in several eukaryotic lineages. Conclusion Recurring intra- and interdomain gene exchange provides an important source of genetic novelty not only in parasitic taxa as previously demonstrated but as we show here, also in free-living protists. Investigating the tempo and mode of evolution of horizontally transferred genes in protists will therefore advance our understanding of mechanisms of adaptation in eukaryotes.

  1. Horizontal versus vertical plate motions

    Directory of Open Access Journals (Sweden)

    M. Cuffaro

    2006-07-01

    Full Text Available We review both present and past motions at major plate boundaries, which have the horizontal component in average 10 to 100 times faster (10–100 mm/yr than the vertical component (0.01–1 mm/yr in all geodynamic settings. The steady faster horizontal velocity of the lithosphere with respect to the upward or downward velocities at plate boundaries supports dominating tangential forces acting on plates. This suggests a passive role of plate boundaries with respect to far field forces determining the velocity of plates. The forces acting on the lithosphere can be subdivided in coupled and uncoupled, as a function of the shear at the lithosphere base. Higher the asthenosphere viscosity, more significant should be the coupled forces, i.e., the mantle drag and the trench suction. Lower the asthenosphere viscosity, more the effects of uncoupled forces might result determinant, i.e., the ridge push, the slab pull and the tidal drag. Although a combination of all forces acting on the lithosphere is likely, the decoupling between lithosphere and mantle suggests that a torque acts on the lithosphere independently of the mantle drag. Slab pull and ridge push are candidates for generating this torque, but, unlike these boundary forces, the advantage of the tidal drag is to be a volume force, acting simultaneously on the whole plates, and being the decoupling at the lithosphere base controlled by lateral variations in viscosity of the low-velocity layer.

  2. Orphan penumbrae: Submerging horizontal fields

    Science.gov (United States)

    Jurčák, J.; Bellot Rubio, L. R.; Sobotka, M.

    2014-04-01

    Aims: We investigate the properties of orphan penumbrae, which are photospheric filamentary structures observed in active regions near polarity inversion lines that resemble the penumbra of regular sunspots but are not connected to any umbra. Methods: We use Hinode data from the Solar Optical Telescope to determine the properties of orphan penumbrae. Spectropolarimetric data are employed to obtain the vector magnetic field and line-of-sight velocities in the photosphere. Magnetograms are used to study the overall evolution of these structures, and G-band and Ca ii H filtergrams are to investigate their brightness and apparent horizontal motions. Results: Orphan penumbrae form between regions of opposite polarity in places with horizontal magnetic fields. Their magnetic configuration is that of Ω-shaped flux ropes. In the two cases studied here, the opposite-polarity regions approach each other with time and the whole structure submerges as the penumbral filaments disappear. Orphan penumbrae are very similar to regular penumbrae, including the existence of strong gas flows. Therefore, they could have a similar origin. The main difference between them is the absence of a "background" magnetic field in orphan penumbrae. This could explain most of the observed differences. Conclusions: The fast flows we detect in orphan penumbrae may be caused by the siphon flow mechanism. Based on the similarities between orphan and regular penumbrae, we propose that the Evershed flow is also a manifestation of siphon flows. A movie attached to Fig. 11 is available in electronic form at http://www.aanda.org

  3. The experiments and characteristic analysis of the sealless cylinder

    Science.gov (United States)

    Kim, Dong-Soo; Bae, Sang-Kyu

    2005-12-01

    Because the general cylinders use sliding seal, The cause the high friction force and adherence phenomenon when They operates in low speed, and the use of the cylinders is not proper in the clean room and high temperature and high pressure environment. Accordingly, in this study, sealless cylinder attaching conical-type piston without seal is proposed to complement the handicap. This paper shows a performance analysis for conical type sealless cylinders and rod bearings. The pistons without seal have partly cylindrical and conical shapes. The 2dimensional Reynolds equation and FD(finite differential) numerical techniques are utilized for the performance analysis. The relationship among self-centering forces and leakage flows are investigated. Also, the optimal design values for a sealless cylinder are presented. A prototype of sealless cylinder which had rod bearing with four pockets, five pockets, and six pockets was manufactured respectively. The leakage flow tests are conducted to evaluate performance of piston and rod bearing in sealless cylinder.

  4. Automatic alignment of multiple magnets into Halbach cylinders

    International Nuclear Information System (INIS)

    Halbach cylinders have found various applications for their ability to produce strong and homogenous magnetostatic fields. Contrary to their conventional manual fabrication, we introduce a novel approach to automatically align multiple permanent magnets into a Halbach cylinder. The approach uses the magnetic field distribution from a diametrically magnetized cylindrical magnet to simultaneously align multiple magnets. The extent to which the automatic assembly can approximate a Halbach cylinder was analyzed using 3D Finite Element Modeling. Prototypes were built that demonstrated automatic alignment of eight magnets into Halbach cylinders. Automatic alignment eliminates the complexity of manually aligning Halbach cylinders. - Highlights: • A new method for fabricating cylindrical Halbach array. • Simultaneously alignment of multiple magnets into Halbach cylinders. • Automatic alignment eliminates the complexity of manually aligning Halbach cylinders

  5. Radiation levels on empty cylinders containing heel material

    Energy Technology Data Exchange (ETDEWEB)

    Shockley, C.W. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    Empty UF{sub 6} cylinders containing heel material were found to emit radiation levels in excess of 200 mr/hr, the maximum amount stated in ORO-651. The radiation levels were as high as 335 mr/hr for thick wall (48X and 48Y) cylinders and 1050 mr/hr for thin wall (48G and 48H) cylinders. The high readings were found only on the bottom of the cylinders. These radiation levels exceeded the maximum levels established in DOT 49 CFR, Part 173.441 for shipment of cylinders. Holding periods of four weeks for thick-wall cylinders and ten weeks for thin-wall cylinders were established to allow the radiation levels to decay prior to shipment.

  6. Numerical simulation for flow around two circular cylinders in tandem

    Science.gov (United States)

    Kondo, Norio; Matsukuma, Daisuke

    2005-05-01

    We use a third-order upwind finite element scheme in order to perform numerical stabilization of solutions of the Navier Stokes equations and present numerical results of flow around two circular cylinders in tandem arrangement by two- and three-dimensional computations. The two circular cylinders are arranged with some spacings between the cylinders. It is well known from experimental data that the flow around two circular cylinders denotes very complicated phenomena with the variation of spacing between two cylinders. In addition, the time-averaged drag coefficients of two circular cylinders suddenly change at a certain spacing between the cylinders. We, therefore, make an investigation of such phenomena at the Reynolds number of 1000 by the use of a numerical approach, and the obtained numerical results are also qualitatively compared with experimental data.

  7. Numerical investigation of local scour at two adjacent cylinders

    Science.gov (United States)

    Kim, Hyung Suk; Nabi, Mohamed; Kimura, Ichiro; Shimizu, Yasuyuki

    2014-08-01

    Local scour around cylinders in a side-by-side or tandem arrangement under clear-water conditions is investigated numerically. Large eddy simulations with a Smagorinsky subgrid model are combined with a ghost-cell immersed boundary method, and details of the bed scouring are realized with sophisticated sediment and morphodynamic models. The scour patterns and depths in the two-cylinder cases are shown to be significantly influenced by the cylinder spacing. The features of the scour evolution, depth, and flow fields for a range of cylinder spacings are discussed. The maximum scour depth in the side-by-side cylinder cases increases as the distance between the cylinders decreases, whereas in the tandem cases, it tends to initially increase with increasing distance between the cylinders, after which it gradually decreases beyond the peak point. The maximum scour depths and trends computed using the present model show good agreement with the measured data in the literature.

  8. Analysis of fatigue life for tube trailer cylinders

    Directory of Open Access Journals (Sweden)

    Xinqi YU

    2015-08-01

    Full Text Available Risk of fatigue failure exists in the tube trailer cylinders under the condition of internal pressure variation and inertial load caused through road transport. In order to estimate the safety state of the cylinders under the action of alternating load, the model of certain geometry sizes is built based on the widely used tube trailer cylinders. The fatigue analysis of tube trailer gas cylinders is made aiming at the action of the internal pressure and the inertial load. The fatigue life distribution of cylinders is obtained under the condition of different loads through the numerical simulation by ANSYS Workbench. The analysis results show that under internal pressure, gas cylinders have limited fatigue life, but can satisfy the requirements; when the inertial load exceeds a certain value, natural gas cylinders of tube trailer is under finite life state, which does not meet the requirements of strength, therefore the inertial load should be controlled.

  9. Fluid structural response of axially cracked cylinders

    International Nuclear Information System (INIS)

    The fluid structural (FS) response of a cylindrical pressure vessel to a suddenly occurring longitudinal through-wall crack is predicted. The effects of vessel internals and depressurization of the compressed water on dynamic crack opening displacements are investigated. A three dimensional (3D) structural finite element model is used as a basis for the development of a two dimensional (2D) FS model. A slice of the vessel taken at the crack midspan and normal to the cylinder axis is modeled. Crack opening displacements are compared between the 2D and 3D models, between the different assumptions about fluid depressurization, and between the static and dynamic solutions. The results show that effects of dynamic amplification associated with the sudden opening of the crack in the cylinder are largely offset by the local depressurization of the fluid adjacent to the crack

  10. Anomalous magnetoresistance in magnetized topological insulator cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Siu, Zhuo Bin, E-mail: a0018876@nus.edu.sg [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 (Singapore); Data Storage Institute, Agency for Science, Technology and Research, Singapore 117608 (Singapore); Jalil, Mansoor B. A. [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 (Singapore)

    2015-05-07

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

  11. Cylinder Flow Control Using Plasma Actuators

    Science.gov (United States)

    Kozlov, Alexey; Thomas, Flint

    2007-11-01

    In this study the results of flow control experiments utilizing single dielectric barrier discharge plasma actuators to control flow separation and unsteady vortex shedding from a circular cylinder in cross-flow are reported. Two optimized quartz dielectric plasma actuators mounted on the cylinder surface utilizing an improved saw-tooth waveform high-voltage generator allowed flow control at Reynolds number approaching supercritical. Using either steady or unsteady actuation, it is demonstrated that the plasma-induced surface blowing gives rise to a local Coanda effect that promotes the maintenance of flow attachment. PIV based flow fields and wake velocity profiles obtained with hot-wire anemometry show large reductions in vortex shedding, wake width and turbulence intensity.

  12. Chaotic rotation of a towed elliptical cylinder

    OpenAIRE

    Weymouth, G. D.

    2014-01-01

    In this paper I consider the self-excited rotation of an elliptical cylinder towed in a viscous fluid as a canonical model of nonlinear fluid structure interactions with possible applications in the design of sensors and energy extraction devices. First, the self-excited ellipse system is shown to be analogous to the forced bistable oscillators studied in classic chaos theory. A single variable, the distance between the pivot and the centroid, governs the system bifurcation into bi-stability....

  13. LiNbO3 Cylinder Fiber

    Science.gov (United States)

    2004-01-01

    We have successfully fabricate optical fiber with a thin layer of LiNbO3 at the boundary of the glass core and dear glass cladding. The construction of this fiber is based on our successful Semiconductor Cylinder Fibers (SCF). A schematic representation of a LiNbO3 Cylinder Fiber is shown. These fibers can be used as light modulators, sonar detectors and in other applications. The core diameter of the fiber is sufficiently small compared to the light wavelength and the indices of refraction of the core and cladding glasses are sufficiently close in value so that there is sufficient light at the core cladding boundary to interact with the LiNbO3 layer. This fiber functions best when just a single light mode propagates through the fiber. The idea for a LiNbO3 Cylinder Fiber came from Dr. Tracee Jamison of NASA. The optical properties of LiNbO3 can be changed with strain or the application of an electric field. Thus these fibers can be used as acoustic sensors as for example in a sonar. They can also be used as electric field operated light modulators. However, for this application the fibers would be made with a cross section in the form of a 'D'. The core with its surrounding LiNbO, layer would be close to the flat portion of the 'D' shaped fiber. Two metal contacts would be deposited on the flat portion of the fiber on either side of the core. A voltage applied across these contacts will result in an electric field in the core region that can be used for modulating the optical properties of the LiNbO, layer. To our knowledge this is the first ever LiNbO, Cylinder Fiber made.

  14. DDES and IDDES of tandem cylinders.

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnan, R.; Garbaruk, A.; Shur, M.; Strelets, M.; Spalart, P.; New Technologies and Services - Russia; St.-Peterburg State Polytechnic Univ.; Boeing Commercial Airplanes

    2010-09-09

    The paper presents an overview of the authors contribution to the BANC-I Workshop on the flow past tandem cylinders (Category 2). It includes an outline of the simulation approaches, numerics, and grid used, the major results of the simulations, their comparison with available experimental data, and some preliminary conclusions. The effect of varying the spanwise period in the simulations is strong for some quantities, and not others.

  15. Miniaturised cylinder head production by rapid prototyping

    OpenAIRE

    Melo, Rodrigo; Monteiro, A. Caetano; Martins, Jorge; Coene, Stijn; Puga, Hélder; Barbosa, J

    2009-01-01

    This work shows the development of the design and manufacturing of a very small engine, namely its head. The engine works under the 4-stroke cycle, therefore having a very complex cylinder head, housing the camshaft, valves and its auxiliaries (seats, guides, springs), spark plug, inlet and exhaust passages and a coolant chamber. The geometries, both inner and outer are highly intricate which makes the production of such a part a very difficult job. In addition, when the engine is...

  16. Cylinder drag Experiment - an upgraded laboratory

    OpenAIRE

    Miller, Clayton William.

    1993-01-01

    Approved for public release; distribution is unlimited. A generalized automated data acquisition system was designed for the Naval Postgraduate School Aerolab Low Speed Wind Tunnel. A specific application of this system was to upgrade the current Cylinder Drag Experiment conducted during AA2801 Aero Laboratories 1, an introductory aeronautical laboratory course taught at the Naval Postgraduate School. Two methods of drag determination were used: pressure distribution and wake analysis (mo...

  17. Cylinder light concentrator and absorber: theoretical description

    OpenAIRE

    Kildishev, Alexander V.; Prokopeva, Ludmila J.; Narimanov, Evgenii

    2010-01-01

    We present a detailed theoretical description of a broadband omnidirectional light concentrator and absorber with cylinder geometry. The proposed optical "trap" captures nearly all the incident light within its geometric cross-section, leading to a broad range of possible applications from solar energy harvesting to thermal light emitters and optoelectronic components. We have demonstrated that an approximate lamellar black-hole with a moderate number of homogeneous layers, while giving the d...

  18. DNA interactions of metallo-supramolecular cylinders

    Czech Academy of Sciences Publication Activity Database

    Malina, Jaroslav; Hannon, M.J.; Brabec, Viktor

    Wroclaw, 2007. s. 245. ISBN 978-83-60043-05-9. [2nd European Conference on Chemistry for Life Sciences. 04.09.2007-08.09.2007, Wroclaw] R&D Projects: GA AV ČR(CZ) KAN200200651; GA AV ČR(CZ) KJB400040601 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : metallo-supramolecular cylinders * DNA three-way junctions * enantioselective DNA binding Subject RIV: BO - Biophysics

  19. Vibroacoustic response of an eccentric hollow cylinder

    Science.gov (United States)

    Hasheminejad, Seyyed M.; Mousavi-akbarzadeh, Hessam

    2012-07-01

    The linear 3D elasticity theory in conjunction with the classical method of separation of variables and the translational addition theorem for cylindrical wave functions are employed to investigate the three-dimensional steady-state sound radiation characteristics of an arbitrarily thick eccentric hollow cylinder of infinite length, submerged in an unbounded ideal acoustic medium, and subjected to arbitrary time-harmonic on-surface mechanical drives. The spatial Fourier transform along the shell axis and Fourier series expansion in the circumferential direction are utilized to obtain a formal integral expression for the radiated pressure field in the frequency domain. The method of stationary phase is subsequently implemented to evaluate the integral for an observation point in the far field. The analytical results are illustrated with numerical examples in which air-filled water-submerged concentric and eccentric steel cylinders are driven by harmonic concentrated radial and transverse surface loads. Effects of excitation and cylinder eccentricity on the far-field radiated pressure amplitudes/directivities are discussed and contributions from pseudo-Rayleigh, whispering gallery, and axially guided waves are examined through selected spatial dispersion patterns. Limiting cases are considered and the validity of results is established with the aid of a commercial finite element package as well as by comparison with the data in the existing literature.

  20. Analysis of mechanical joint in composite cylinder

    Science.gov (United States)

    Hong, C. S.; Kim, Y. W.; Park, J. S.

    Joining techniques of composite materials are of great interest in cylindrical structures as the application of composites is widely used for weight-sensitive structures. Little information for the mechanical fastening joint of the laminated shell structure is available in the literature. In this study, a finite element program, which was based on the first order shear deformation theory, was developed for the analysis of the mechanical joint in the laminated composite structure. The failure of the mechanical fastening joint for the laminated graphite/epoxy cylinder subject to internal pressure was analyzed by using the developed program. Modeling of the bolt head in the composite cylinder was studied, and the effect of steel reinforcement outside the composite cylinder on the failure was investigated. The stress component near the bolt head was influenced by the size of the bolt head. The failure load and the failure mode were dependent on the bolt diameter, the number of bolts, and fiber orientation. The failure load was constant when the edge distance exceeds three times the bolt diameter.

  1. Cylinder with differential piston for mass measurements

    International Nuclear Information System (INIS)

    The paper presents a cylinder with differential piston, adapted for measuring the weight of fixed objects such as: fuel tanks (regardless of their capacity), bunkers and silos for all kind of materials, or mobile objects such as: automobiles, trucks, locomotives and railway cars. Although, the cylinder with differential piston is used on a large scale in hydraulic drive or hydraulic control circuits, till now it was not used as constituent part for weight measurements devices. The novelty of the present paper is precisely the use of the device for such purposes. Based on a computation algorithm, the paper presents the general design (assembly), of the device used for weighing important masses (1…. 100 tones). The fundamental idea consist in the fact that, a mass over 10 tones may be weighted with a helicoidally spring subjected to an axial force between 0 and 3000 N, with a deflection of about 30 mm. Simultaneously with the mechanical part, the electronic recording system is also described. The great advantage of the presented device consist in the fact that it can be used in heavy polluted atmosphere or difficult topographic conditions as a result of both the small dimensions and the protection systems adopted. Keywords: cylinder hydraulic with differential piston, hydrostatic pressure, measuring devices

  2. Solvable critical dense polymers on the cylinder

    International Nuclear Information System (INIS)

    A lattice model of critical dense polymers is solved exactly on a cylinder with finite circumference. The model is the first member LM(1,2) of the Yang–Baxter integrable series of logarithmic minimal models. The cylinder topology allows for non-contractible loops with fugacity α that wind around the cylinder or for an arbitrary number l of defects that propagate along the full length of the cylinder. Using an enlarged periodic Temperley–Lieb algebra, we set up commuting transfer matrices acting on states whose links are considered distinct with respect to connectivity around the front or back of the cylinder. These transfer matrices satisfy a functional equation in the form of an inversion identity. For even N, this involves a non-diagonalizable braid operator J and an involution R = − (J3 − 12J)/16 = (−1)F with eigenvalues R=(-1)l/2. This is reminiscent of supersymmetry with a pair of defects interpreted as a fermion. The number of defects l thus separates the theory into Ramond (l/2 even), Neveu–Schwarz (l/2 odd) and Z4 (l odd) sectors. For the case of loop fugacity α = 2, the inversion identity is solved exactly sector by sector for the eigenvalues in finite geometry. The eigenvalues are classified according to the physical combinatorics of the patterns of zeros in the complex spectral-parameter plane. This yields selection rules for the physically relevant solutions to the inversion identity. The finite-size corrections are obtained from Euler–Maclaurin formula. In the scaling limit, we obtain the conformal partition functions as sesquilinear forms and confirm the central charge c = − 2 and conformal weights Δ, Δ-bar =Δt=(t2-1)/8. Here t=l/2 and t=2r-s element of N in the l even sectors with Kac labels r = 1, 2, 3,...;s = 1, 2 while t ∈ Z - ½ in the l odd sectors. Strikingly, the l/2 odd sectors exhibit a W-extended symmetry but the l/2 even sectors do not. Moreover, the naive trace summing over all l even sectors does not yield a

  3. Evaluation of Cylinder Volume Estimation Methods for In–Cylinder Pressure Trace Analysis

    Directory of Open Access Journals (Sweden)

    Adrian Irimescu

    2012-09-01

    Full Text Available In–cylinder pressure trace analysis is an important investigation tool frequently employed in the study of internal combustion engines. While technical data is usually available for experimental engines, in some cases measurements are performed on automotive engines for which only the most basic geometry features are available. Therefore, several authors aimed to determine the cylinder volume and length of the connecting rod by other methods than direct measurement. This study performs an evaluation of two such methods. The most appropriate way was found to be the estimation of connecting rod length based on general engine category as opposed to the use of an equation that predicts cylinder volume with good accuracy around top dead centre for most geometries.

  4. CNG Cylinder Safety - Education, Outreach, and Next Steps (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.; Schroeder, A.

    2014-01-01

    Mr. Schroeder discussed the work that NREL is performing for the U.S. Department of Transportation on compressed natural gas cylinder end-of-life requirements. CNG vehicles are different from most other vehicles in that the CNG fuel storage cylinders have a pre-determined lifetime that may be shorter than the expected life of the vehicle. The end-of-life date for a cylinder is based on construction and test protocols, and is specific to the construction and material of each cylinder. The end-of-life date is important because it provides a safe margin of error against catastrophic cylinder failure or rupture. The end-of-life dates range from 15 to 25 years from the date of manufacture. NREL worked to develop outreach materials to increase awareness of cylinder end-of-life dates, has provided technical support for individual efforts related to cylinder safety and removal, and also worked with CVEF to document best practices for cylinder removal or inspection after an accident. Mr. Smith discussed the engagement of the DOE Clean Fleets Partners, which were surveyed to identify best practices on managing cylinder inventories and approached to provide initial data on cylinder age in a fleet environment. Both DOE and NREL will continue to engage these fleets and other stakeholders to determine how to best address this issue moving forward.

  5. Optimization of autofrettage in thick-walled cylinders

    Directory of Open Access Journals (Sweden)

    A. Ghomi

    2006-04-01

    Full Text Available Purpose: The purpose of this paper is optimization of the weight of compound cylinder for a specific pressure. The variables are shrinkage radius and shrinkage tolerance.Design/methodology/approach: SEQ technique for optimization, the finite element code, ANSYS for numerical simulation are employed to predict the optimized conditions. The results are verified by testing a number of closed end cylinders with various geometries, materials and internal pressures.Findings: The weight of a compound cylinder could reduce by 60% with respect to a single steel cylinder. The reduction is more significant at higher working pressures. While the reduction of weight is negligible for k<2.5, it increases markedly for 2.5cylinders become equal to the yield stresses of the materials used for compound cylinders. The experimental results showed higher bursting pressure for optimized cylinders.Research limitations/implications: The research must be done for non-linear material models and for multiple compound cylinders.Practical implications: The results can be used for high pressure vessels such as artillery tubes, gun barrels and son on.Originality/value: The numerical results indicated that for an optimum condition, the stress at the internal radii of the outer and inner cylinders become equal to the yield stresses of the materials used for compound cylinders.

  6. Measurements of the Flowfield Interaction Between Tandem Cylinders

    Science.gov (United States)

    Neuhart, Dan H.; Jenkins, Luther N.; Choudhari, Meelan M.; Khorrami, Mehdi R.

    2009-01-01

    This paper presents the most recent measurements from an ongoing investigation of the unsteady wake interference between a pair of circular cylinders in tandem. The purpose of this investigation is to help build an in-depth experimental database for this canonical flow configuration that embodies the effects of component interaction in landing gear noise. This new set of measurements augments the previous database at the primary Reynolds number (based on tunnel speed and cylinder diameter) of 1.66 105 in four important respects. First, better circumferential resolution of surface pressure fluctuations is obtained via cylinder "clocking". Second, higher resolution particle image velocimetry measurements of the shear layer separating from the cylinders are achieved. Third, the effects of simultaneous boundary layer trips along both the front and rear cylinders, versus front cylinder alone in the previous measurements, are studied. Lastly, on-surface and off-surface characteristics of unsteady flow near the "critical" cylinder spacing, wherein the flow switches intermittently between two states that are characteristic of lower and higher spacings, are examined. This critical spacing occurs in the middle of a relatively sudden change in the drag of either cylinder and is characterized by a loud intermittent noise and a flow behavior that randomly transitions between shear layer attachment to the rear cylinder and constant shedding and rollup in front of it. Analysis of this bistable flow state reveals much larger spanwise correlation lengths of surface pressure fluctuations than those at larger and smaller values of the cylinder spacing.

  7. Theoretical and experimental stress analyses of ORNL thin-shell cylinder-to-cylinder model 4

    International Nuclear Information System (INIS)

    The last in a series of four thin-shell cylinder-to-cylinder models was tested, and the experimentally determined elastic stress distributions were compared with theoretical predictions obtained from a thin-shell finite-element analysis. The models in the series are idealized thin-shell structures consisting of two circular cylindrical shells that intersect at right angles. There are no transitions, reinforcements, or fillets in the junction region. This series of model tests serves two basic purposes: (1) the experimental data provide design information directly applicable to nozzles in cylindrical vessels, and (2) the idealized models provide test results for use in developing and evaluating theoretical analyses applicable to nozzles in cylindrical vessels and to thin piping tees. The cylinder of model 4 had an outside diameter of 10 in., and the nozzle had an outside diameter of 1.29 in., giving a d0/D0 ratio of 0.129. The OD/thickness ratios were 50 and 20.2 for the cylinder and nozzle respectively. Thirteen separate loading cases were analyzed. For each loading condition one end of the cylinder was rigidly held. In addition to an internal pressure loading, three mutually perpendicular force components and three mutually perpendicular moment components were individually applied at the free end of the cylinder and at the end of the nozzle. The experimental stress distributions for each of the 13 loadings were obtained using 157 three-gage strain rosettes located on the inner and outer surfaces. Each of the 13 loading cases was also analyzed theoretically using a finite-element shell analysis developed at the University of California, Berkeley. The analysis used flat-plate elements and considered five degrees of freedom per node in the final assembled equations. The comparisons between theory and experiment show reasonably good agreement for this model. (U.S.)

  8. Theoretical and experimental stress analyses of ORNL thin-shell cylinder-to-cylinder model 3

    International Nuclear Information System (INIS)

    The third in a series of four thin-shell cylinder-to-cylinder models was tested, and the experimentally determined elastic stress distributions were compared with theoretical predictions obtained from a thin-shell finite-element analysis. The models are idealized thin-shell structures consisting of two circular cylindrical shells that intersect at right angles. There are no transitions, reinforcements, or fillets in the junction region. This series of model tests serves two basic purposes: the experimental data provide design information directly applicable to nozzles in cylindrical vessels; and the idealized models provide test results for use in developing and evaluating theoretical analyses applicable to nozzles in cylindrical vessels and to thin piping tees. The cylinder of model 3 had a 10 in. OD and the nozzle had a 1.29 in. OD, giving a d0/D0 ratio of 0.129. The OD/thickness ratios for the cylinder and the nozzle were 50 and 7.68 respectively. Thirteen separate loading cases were analyzed. In each, one end of the cylinder was rigidly held. In addition to an internal pressure loading, three mutually perpendicular force components and three mutually perpendicular moment components were individually applied at the free end of the cylinder and at the end of the nozzle. The experimental stress distributions for all the loadings were obtained using 158 three-gage strain rosettes located on the inner and outer surfaces. The loading cases were also analyzed theoretically using a finite-element shell analysis developed at the University of California, Berkeley. The analysis used flat-plate elements and considered five degrees of freedom per node in the final assembled equations. The comparisons between theory and experiment show reasonably good agreement for this model. (U.S.)

  9. Convergence substitution for paralysed horizontal gaze.

    OpenAIRE

    Beigi, B.; O'Keeffe, M; Logan, P; Eustace, P.

    1995-01-01

    Three patients with paralysed horizontal gaze are presented. Involuntary use of convergence to assist horizontal gaze was noted as a late feature. All patients showed (1) unilateral or bilateral horizontal gaze palsy (two patients had one and a half syndrome, the other had bilateral nuclear sixth nerve palsies), (2) adduction of both eyes on attempted gaze into the paralysed field, (3) miosis which coincided with adduction. Convergence substitution should be considered in the differential dia...

  10. Spray controller for horizontal boom movements compensation

    OpenAIRE

    El Bahir, Loussain; Lebeau, Frédéric; Destain, Marie-France; Kinnaert; Hanus, Raymond

    2002-01-01

    Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles. Manufacturers classically try to reduce unwanted nozzles movements using horizontal boom suspension but these methods show performance and price limitations. The purpose of this paper is to propose a spray controller aiming to compensate the effect of the horizontal boom movements on the spray distribution besides the effect of tractor speed variations. The controller is based on ...

  11. System for Estimating Horizontal Velocity During Descent

    Science.gov (United States)

    Johnson, Andrew; Cheng, Yang; Wilson, Reg; Goguen, Jay; Martin, Alejandro San; Leger, Chris; Matthies, Larry

    2007-01-01

    The descent image motion estimation system (DIMES) is a system of hardware and software, designed for original use in estimating the horizontal velocity of a spacecraft descending toward a landing on Mars. The estimated horizontal velocity is used in generating rocket-firing commands to reduce the horizontal velocity as part of an overall control scheme to minimize the landing impact. DIMES can also be used for estimating the horizontal velocity of a remotely controlled or autonomous aircraft for purposes of navigation and control.

  12. A Forced System of Two Cylinders with Various Spacings

    Institute of Scientific and Technical Information of China (English)

    邹建锋; 任安禄; 邓见

    2004-01-01

    The spectrum characteristics and wake structures for a circular cylinder oscillating in a wake are investigated by use of the currently modified virtual boundary method. A forced system of two cylinders with a small spacing (the downstream one is made to oscillate in the transverse direction) is studied and interesting flow characteristics are observed. A vortex switch and the change of vortex modes (between 2S mode and 2P mode) are observed in the "lock-in" region. Vortex bands are formed and lost with the increasing excitation frequency. Information concerning saddle points in the flow field is obtained for different excitation frequencies. For a forced system of two cylinders with a large spacing, the upstream cylinder sheds vortexes because there is no downstream cylinder oscillating in the wake. No distinct "lock-in" response is found for the downstream cylinder.

  13. Next Generations Safeguards Initiative: The Life of a Cylinder

    International Nuclear Information System (INIS)

    The U.S. Department of Energy/National Nuclear Security Administration Office of Nonproliferation and International Security's Next Generation Safeguards Initiative (NGSI) has begun a program based on a five-year plan to investigate the concept of a global monitoring scheme that uniquely identifies uranium hexafluoride (UF6) cylinders and their locations throughout the life cycle. A key initial activity in the NGSI program is to understand and document the 'life of a UF6 cylinder' from cradle to grave. This document describes the life of a UF6 cylinder and includes cylinder manufacture and procurement processes as well as cylinder-handling and operational practices at conversion, enrichment, fuel fabrication, and depleted UF6 conversion facilities. The NGSI multiple-laboratory team is using this document as a building block for subsequent tasks in the five-year plan, including development of the functional requirements for cylinder-tagging and tracking devices.

  14. Experimental study of a three dimensional cylinder-filament system

    CERN Document Server

    Brosse, Nicolas; Lundell, Fredrik; Bagheri, Shervin

    2015-01-01

    This experimental study reports on the behavior of a filament attached to the rear of a three- dimensional cylinder. The axis of the cylinder is placed normal to a uniform incoming flow and the filament is free to move in the cylinder wake. The mean position of the filament is studied as a function of the filament length L. It is found that for long (L/D > 6.5, where D is the cylinder diameter) and short (L/D < 2) filaments the mean position of the filament tends to align with the incoming flow, whereas for intermediate filament lengths (2 < L/D < 6.5) the filament lies down on the cylinder and tends to align with the cylinder axis. The underlying mechanism of the bifurcations are discussed and related to buckling and inverted-pendulum-like instabilities.

  15. Vortex structure behind highly heated two cylinders in parallel arrangements

    International Nuclear Information System (INIS)

    Vortex structures behind twin, highly heated cylinders in parallel arrangements have been investigated experimentally. The experiments were conducted under the following conditions: cylinder diameter, D=4 mm; mean flow velocity, U∞=1.0 m/s; Reynolds number, Re=250; cylinder clearance, S/D=0.5 - 1.4; and cylinder heat flux, q=0 - 72.6 kW/m2. For S/D > 1.2, the Karman vortex street is formed alternately behind each cylinder divided on the slit flow. The slit flow velocity increases with a decrease in S/D and decreases with increasing heat flux. For S/D2). As a result, the increased local kinematic viscosity and S/D play a key role for the vortex structure and formation behind arrangements of two parallel cylinders. (author)

  16. Acoustics and Surface Pressure Measurements from Tandem Cylinder Configurations

    Science.gov (United States)

    Hutcheson, Florence V.; Brooks, Thomas F.; Lockard, David P.; Choudhari, Meelan M.; Stead, Daniel J.

    2014-01-01

    Acoustic and unsteady surface pressure measurements from two cylinders in tandem configurations were acquired to study the effect of spacing, surface trip and freestream velocity on the radiated noise. The Reynolds number ranged from 1.15x10(exp 5) to 2.17x10(exp 5), and the cylinder spacing varied between 1.435 and 3.7 cylinder diameters. The acoustic and surface pressure spectral characteristics associated with the different flow regimes produced by the cylinders' wake interference were identified. The dependence of the Strouhal number, peak Sound Pressure Level and spanwise coherence on cylinder spacing and flow velocity was examined. Directivity measurements were performed to determine how well the dipole assumption for the radiation of vortex shedding noise holds for the largest and smallest cylinder spacing tested.

  17. Imperfection effects on the buckling of hydrostatically loaded cylinders

    DEFF Research Database (Denmark)

    Pinna, Rodney; Madsen, Søren

    2015-01-01

    in design has also increased. Practical guidance on how to do this is fairly limited, in particular for geometries or load conditions other than the standard cases. The effect of imperfections on the collapse load of cylinders under axial load has been studied extensively, as such cylinders show the......The presence of geometric and other imperfections in cylinders has been known to result in collapse loads well below those predicted from eigenvalue analysis for a long time. As the designer's ability to routinely employ non-linear FEA has increased, the importance of modelling such imperfections...... largest imperfection sensitivity. Work on cylinders with other loading conditions, such as hydrostatic loading, is more limited. Similarly, there is limited work on cylinders with boundary conditions other than simply-supported ends. This paper looks at the case of cylinders under hydrostatic load, which...

  18. Effect of Surface Coatings on Cylinders Exposed to Underwater Shock

    Directory of Open Access Journals (Sweden)

    Y.W. Kwon

    1994-01-01

    Full Text Available The response of a coated cylinder (metallic cylinder coated with a rubber material subjected to an underwater explosion is analyzed numerically. The dynamic response of the coated cylinder appears to be adversely affected when impacted by an underwater shock wave under certain conditions of geometry and material properties of the coating. When adversely affected, significant deviations in values of axial stress, hoop stress, and strain are observed. The coated cylinder exhibits a larger deformation and higher internal energy in the metallic material. Rubber coatings appeared to inhibit energy dissipation from the metallic material to the surrounding water medium. A parametric study of various coatings was performed on both aluminum and steel cylinders. The adverse effect of the coating decreased when the stiffness of the rubber layer increased, indicating the existence of a threshold value. The results of this study indicate that the stiffness of the coating is a critical factor to the shock hardening of the coated cylinder.

  19. Flow-induced vibrations of a rotating cylinder

    OpenAIRE

    Bourguet, Rémi; Lo Jacono, David

    2014-01-01

    International audience The flow-induced vibrations of a circular cylinder, free to oscillate in the cross-flow direction and subjected to a forced rotation about its axis, are analysed by means of two- and three-dimensional numerical simulations. The impact of the symmetry breaking caused by the forced rotation on the vortex-induced vibration (VIV) mechanisms is investigated for a Reynolds number equal to 100, based on the cylinder diameter and inflow velocity. The cylinder is found to osc...

  20. Properties of axial surface waves along dielectrically coated conducting cylinders

    OpenAIRE

    Siart, U.; Adrian, S.; Eibert, T.

    2012-01-01

    In this paper the fundamental properties of surface waves along conducting cylinders with and without dielectric coating are investigated for cylinder diameters in the centimeter range and frequencies in the gigahertz range and higher. Analytical results for the phase constant and attenuation versus the cylinder radius are derived and cutoff frequencies of various TE, TM, and hybrid waves are computed. The radial power distribution is computed in order to investi...

  1. Scattering by closely spaced infinite cylinders in an absorbing medium

    Directory of Open Access Journals (Sweden)

    S.-C. Lee

    2011-09-01

    Full Text Available Scattering by closely spaced parallel infinite cylinders in an absorbing medium is considered in this paper. The source wave is arbitrarily polarized and propagates in a general direction at the cylinders. The formulation utilizes the Hertz potential approach, and the scattering cross section and intensity distribution in the far-field are developed. Numerical results are presented to illustrate the influence of the absorbing medium on the scattering properties of two configurations of closely-spaced cylinders.

  2. Evaluation of Satisfaction and Axial Rigidity with Titan XL Cylinders

    OpenAIRE

    Gerard D. Henry; Caroline Jennermann; J. Francois Eid

    2012-01-01

    The inflatable penile prosthesis (IPP) has high patient satisfaction rates and good mechanical reliability rates in multiple studies. The number one patient compliant at six months is penile length. Recently, new technique for aggressive sizing of the cylinders has been published on in the literature. One IPP company has produced a new product that has longer length cylinders (XL) than those available. However, traditionally long cylinders were felt to lack axial rigidity. Therefore, a prospe...

  3. Casimir interaction between two concentric cylinders at nonzero temperature

    OpenAIRE

    L.P. Teo

    2011-01-01

    We study the finite temperature Casimir interaction between two concentric cylinders. When the separation between the cylinders is much smaller than the radii of the cylinders, the asymptotic expansions of the Casimir interaction are derived. Both the low temperature and the high temperature regions are considered. The leading terms are found to agree with the proximity force approximations. The low temperature leading term of the temperature correction is also computed and it is found to be ...

  4. Paramagnetic Reentrance Effect in NS Proximity Cylinders

    OpenAIRE

    Maki, Kazumi; Haas, Stephan

    2000-01-01

    A scenario for the unusual paramagnetic reentrance behavior at ultra-low temperatures in Nb-Ag, Nb-Au, and Nb-Cu cylinders is presented. For the diamagnetic response down to temperatures of the order 15 mK, the standard theory (quasi-classical approximation) for superconductors appears to work very well, assuming that Ag, Au, and Cu remain in the normal state except for the proximity-induced superconductivity. Here it is proposed that these noble metals may become p-wave superconductors with ...

  5. Cylindrical vortex wake model: right cylinder

    DEFF Research Database (Denmark)

    Branlard, Emmanuel; Gaunaa, Mac

    2015-01-01

    The vortex system consisting of a bound vortex disk, a root vortex and a vortex cylinder as introduced by Joukowski in 1912 is further studied in this paper. This system can be used for simple modeling of rotors (e.g. wind turbines) with infinite number of blades and finite tip-speed ratios. For...... each vortex element, the velocity components in all directions and in the entire domain are computed analytically in a novel approach. In particular, the velocity field from the vortex actuator disk is derived for the first time. The induction from the entire vortex system is studied and is seen to...

  6. Stability of the charged radiating cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, M., E-mail: msharif.math@pu.edu.pk; Zaeem Ul Haq Bhatti, M., E-mail: mzaeem.math@gmail.com

    2014-01-24

    We discuss the dynamical instability of cylindrically symmetric isotropic geometry under the effect of electromagnetic field. The interior geometry of the dynamical collapse is matched with an exterior geometry through Darmois junction conditions. The perturbation scheme is used to describe the collapse equation and categorize the Newtonian and post-Newtonian regions in radiating as well as non-radiating eras. It is concluded that energy density, pressure, radiation density and electromagnetic field control the stability of the cylinder leading to more unstable configuration.

  7. Cylinder light concentrator and absorber: theoretical description.

    Science.gov (United States)

    Kildishev, Alexander V; Prokopeva, Ludmila J; Narimanov, Evgenii E

    2010-08-01

    We present a detailed theoretical description of a broadband omnidirectional light concentrator and absorber with cylinder geometry. The proposed optical "trap" captures nearly all the incident light within its geometric cross-section, leading to a broad range of possible applications--from solar energy harvesting to thermal light emitters and optoelectronic components. We have demonstrated that an approximate lamellar black-hole with a moderate number of homogeneous layers, while giving the desired ray-optical performance, can provide absorption efficiencies comparable to those of ideal devices with a smooth gradient in index. PMID:20721056

  8. An update on corrosion monitoring in cylinder storage yards

    Energy Technology Data Exchange (ETDEWEB)

    Henson, H.M.; Newman, V.S.; Frazier, J.L. [Oak Ridge K-25 Site, TN (United States)

    1991-12-31

    Depleted uranium, from US uranium isotope enrichment activities, is stored in the form of solid uranium hexafluoride (UF{sub 6}) in A285 and A516 steel cylinders designed and manufactured to ASME Boiler and Pressure Vessel Code criteria. In general, storage facilities are open areas adjacent to the enrichment plants where the cylinders are exposed to weather. This paper describes the Oak Ridge program to determine the general corrosion behavior of UF{sub 6} cylinders, to determine cylinder yard conditions which are likely to affect long term storage of this material, and to assess cylinder storage yards against these criteria. This program is targeted at conditions specific to the Oak Ridge cylinder yards. Based on (a) determination of the current cylinder yard conditions, (b) determination of rusting behavior in regions of the cylinders showing accelerated attack, (c) monitoring of corrosion rates through periodic measurement of test coupons placed within the cylinder yards, and (d) establishment of a computer base to incorporate and retain these data, the technical division is working with the enrichment sites to implement an upgraded system for storage of this material until such time as it is used or converted.

  9. Enrichment Assay Methods Development for the Integrated Cylinder Verification System

    International Nuclear Information System (INIS)

    International Atomic Energy Agency (IAEA) inspectors currently perform periodic inspections at uranium enrichment plants to verify UF6 cylinder enrichment declarations. Measurements are typically performed with handheld high-resolution sensors on a sampling of cylinders taken to be representative of the facility's entire product-cylinder inventory. Pacific Northwest National Laboratory (PNNL) is developing a concept to automate the verification of enrichment plant cylinders to enable 100 percent product-cylinder verification and potentially, mass-balance calculations on the facility as a whole (by also measuring feed and tails cylinders). The Integrated Cylinder Verification System (ICVS) could be located at key measurement points to positively identify each cylinder, measure its mass and enrichment, store the collected data in a secure database, and maintain continuity of knowledge on measured cylinders until IAEA inspector arrival. The three main objectives of this FY09 project are summarized here and described in more detail in the report: (1) Develop a preliminary design for a prototype NDA system, (2) Refine PNNL's MCNP models of the NDA system, and (3) Procure and test key pulse-processing components. Progress against these tasks to date, and next steps, are discussed.

  10. Numerical Investigation of 3D Flow Around Two Tandem Cylinders

    OpenAIRE

    Kalvig, Ragnhild Birgitte Hidle

    2015-01-01

    Circular cylinders in tandem arrangement are used in many marine applications like dual pipelines and dual risers. Turbulent flow in 3D around two tandem cylinders is simulated numerically using Large Eddy Simulation (LES) with a Smagorinsky subgrid scale model. The Reynolds number based on the cylinder diameter of 1 meter and free stream velocity of $U=1.31$ m/s is 13100, which is in the subcritical flow regime. The center-to-center spacing between the cylinders is $S/D=5$. The software used...

  11. LES of the flow around two cylinders in tandem

    Science.gov (United States)

    Palau-Salvador, G.; Stoesser, T.; Rodi, W.

    2008-11-01

    The flow around an arrangement of two cylinders in tandem exhibits a remarkably complex behaviour that is of interest for many engineering problems, such as environmental flows or structural design. In the present paper, a Large Eddy Simulation using a staggered Cartesian grid has been performed for the flow around two cylinders in tandem of diameter D=20mm and height H=50mm submerged in an open channel with height h=60mm. The two axes have a streamwise spacing of 2D. The Reynolds number is 1500, based on the cylinder diameter and the free-stream velocity u. The results obtained show that no vortex shedding occurs in the gap between the two cylinders where the separated shear layers produced by the upstream cylinder reattach on the surface of the downstream one. The flow separates on the top of the first cylinder with the presence of two spiral nodes known as owl-face configuration. On top of the downstream cylinder, the flow is attached. A complex mean flow develops in the gap and also behind the second cylinder. Comparisons with PIV measurements reveal good general agreement, but there are differences concerning some details of the flow in the gap between the cylinders.

  12. An experiments and characteristics analysis of the sealless cylinder

    International Nuclear Information System (INIS)

    This paper shows a performance analysis for conical type sealless cylinders and rod bearings. The pistons without seal have partly cylindrical and conical shapes. 2 dimensional Reynolds equation and FD(Finite Differential) numerical techniques are utilized for the performance analysis. The relationship among self-centering forces and leakage flows are investigated. Also, optimal design values for a sealless cylinder are presented. A prototype of sealless cylinder which had rod bearing with four pockets, five pockets, and six pockets was manufactured respectively. Leakage flow test is conducted to evaluate performance of piston and rod bearing in sealless cylinder

  13. Pareter Study of Some Key Structures for Cylinder Head

    Institute of Scientific and Technical Information of China (English)

    张儒华; 左正兴; 曹丽亚; 廖日东

    2004-01-01

    Using the method of the pareter study, some important dimensions of the cylinder head of an internal-combustion engine are analyzed. Under the mechanical load, the variational rules of the von Mises maximum stress on cylinder head are obtained, which are influenced by the thickness of the floor plate, head plate, jobbing sheet, standing partition board, and side plate of inlet port and exhaust port. A hypothesis is verified that there is an ideal matching point ong those above-mentioned main pareters. The quantificational proportion relations, between these key structural pareters and von Mises maximum stress of cylinder head, can provide a good help for the cylinder head's structural design.

  14. Coupled Thermo-Mechanical Analyses of Dynamically Loaded Rubber Cylinders

    Science.gov (United States)

    Johnson, Arthur R.; Chen, Tzi-Kang

    2000-01-01

    A procedure that models coupled thermo-mechanical deformations of viscoelastic rubber cylinders by employing the ABAQUS finite element code is described. Computational simulations of hysteretic heating are presented for several tall and short rubber cylinders both with and without a steel disk at their centers. The cylinders are compressed axially and are then cyclically loaded about the compressed state. The non-uniform hysteretic heating of the rubber cylinders containing a steel disk is presented. The analyses performed suggest that the coupling procedure should be considered for further development as a design tool for rubber degradation studies.

  15. Flow past two tandem square cylinders vibrating transversely in phase

    International Nuclear Information System (INIS)

    Numerical investigations have been carried out to study the wake characteristics of flow past two tandem square cylinders vibrating in phase. Both the cylinders vibrate in a transverse direction, i.e., perpendicular to the incoming flow with the same frequency and amplitude. The frequency of vibration of the cylinders and the inter-cylinder spacing are varied for fixed values of the Reynolds number (Re = 100) and the amplitude ratio (A/D = 0.4). The synchronous or lock-in regime for the oscillatory wake of the vibrating cylinders has been identified by varying the frequency of the vibration from fe = 0.4 f0 to 1.6 f0 (f0 being the frequency of vortex shedding behind a stationary square cylinder). The characteristics of lift and drag and the mechanism of vortex shedding are studied by varying the excitation frequency within the lock-in range for each value of inter-cylinder spacing. The complex interaction of flow between the cylinders gives rise to a variety of characteristically different shedding patterns in their wake. For values of inter-cylinder spacing equal to 2D and 3D, periodic, as well as quasi-periodic, lock-in behaviors are observed in the synchronous range. (paper)

  16. Prediction of External Corrosion for Steel Cylinders--2007 Report

    Energy Technology Data Exchange (ETDEWEB)

    Schmoyer, Richard L [ORNL

    2008-01-01

    Depleted uranium hexafluoride (DUF{sub 6}) is stored in over 62,000 containment cylinders at the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and at the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. Over 4,800 of the cylinders at Portsmouth were recently moved there from the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee. The cylinders range in age up to 56 years and come in various models, but most are 48-inch diameter 'thin-wall'(312.5 mil) and 'thick-wall' (625 mil) cylinders and 30-inch diameter '30A' (including '30B') cylinders with 1/2-inch (500 mil) walls. Most of the cylinders are carbon steel, and they are subject to corrosion. The United States Department of Energy (DOE) manages the cylinders to maintain them and the DUF{sub 6} they contain. Cylinder management requirements are specified in the System Requirements Document (LMES 1997a), and the activities to fulfill them are specified in the System Engineering Management Plan (LMES 1997b). This report documents activities that address DUF{sub 6} cylinder management requirements involving measuring and forecasting cylinder wall thicknesses. As part of these activities, ultrasonic thickness (UT) measurements are made on samples of cylinders. For each sampled cylinder, multiple measurements are made in an attempt to find, approximately, the minimum wall thickness. Some cylinders have a skirt, which is an extension of the cylinder wall to protect the head (end) and valve. The head/skirt interface crevice is thought to be particularly vulnerable to corrosion, and for some skirted cylinders, in addition to the main body UT measurements, a separate suite of measurements is also made at the head/skirt interface. The main-body and head/skirt minimum thickness data are used to fit models relating minimum thickness to cylinder age, nominal thicknesses, and cylinder functional groups defined in terms of plant site, storage yard

  17. Analysis of a Lifting Fixture to Hold a Steel Mandrel Horizontally from one End Support

    International Nuclear Information System (INIS)

    A lifting fixture (drawing number 3823.113-MD-372382) that lifts large steel mandrels from one end through the mandrel's end support web is described. The mandrels are used as a mold to form carbon fiber cylinders. The mandrels are held from one end to allow the carbon cylinder to be pulled horizontally off the mandrel. Only mandrels as described in drawing numbers 3823.113-MD-358992 and 3823.1 13-MD-358994 are lifted by the fixture. The largest mandrel is 41 inches in diameter, 120 inches long, and weighs approximately 3,000 lbs. A detailed procedure for removing the carbon cylinder from the steel mandrel is given in the Appendix. The fixture is to be supported only using Fermilab Forklift 10207 or equivalent. The forklift has a nameplate capacity of 12,000 lbs 24 inches from the mast at an elevation of 130 inches from the floor. The forklift forks must be removed from the truck prior to using the fixture. The forklift is to be used to support the mandrels only during the lifting operation and is not to be used to transport the mandrels. Stresses at the lifting fixture are shear stresses on the support brackets due to the overall weight of the mandrel and moment loads due to the cantilever style suppOrt. The moment on the forklift due to the overhanging weight of the mandrel is calculated. Stresses in the mandrel due to the method of support are also described.

  18. Horizontal drilling assessment in Western Canada

    International Nuclear Information System (INIS)

    The first horizontal well was drilled in Saskatchewan in 1987. Since then, the number of horizontal wells drilled has escalated rapidly, averaging approximately 500 per year since 1993. When combined with horizontal wells drilled in Alberta, the major Canadian oil-producing province, the total number drilled in 1995 was 978. This total exceeds the National Energy Board (NEB) projected maximum of 816 wells per year. The NEB projections were based on a break-even point for the drilling of horizontal wells of a return of CDN $285,000 using a discount rate of 15%. This corresponded to a cumulative production from each individual well of some 11,000 m3. The introduction of a royalty-free production volume of 12,000 m3 per horizontal well in Saskatchewan was instrumental in stimulating the rapid expansion in the use of horizontal wells and helping Canada to exceed the forecasted drilling level. Within Saskatchewan, daily production from 1964 active horizontal wells is in excess of 20,000 m3. Comparative analysis indicates that the average daily production per well has increased from approximately by 40% with the advent of horizontal wells. In total production terms, provincial production has increased from 11.7 million cubic metres in 1989 to 20.9 million m3 in 1996. This represents an increase of almost 79% based primarily on the extensive use of horizontal wells. In 1996, horizontal wells produced 36% of the province's oil from 12% of the active wells. In the southeastern producing areas of Saskatchewan, the Williston Basin, declining oil-production has jumped 100%, with horizontal wells accounting for approximately 50% of total regional production. Pay zones in this areas, as in most of the province, tend to be relatively thin, with net pay frequently less that 5 m. The modest investment of some CDN $5 million in government research funding 10 years ago to stimulate the development of horizontal wells, combined with a favourable royalty structure, has been at least

  19. Near-wake flow structure of elliptic cylinders close to a free surface: effect of cylinder aspect ratio

    Energy Technology Data Exchange (ETDEWEB)

    Daichin, Sang Joon Lee [Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-Dong, 790-784, Nam-gu, Pohang (Korea)

    2004-05-01

    The flow fields behind elliptic cylinders adjacent to a free surface were investigated experimentally in a circulating water channel. A range of cylinder aspect ratios (AR=2, 3, 4) were considered, while the cross-sectional area of the elliptical cylinder was kept constant. The main objective of this study was to investigate the effect of cylinder aspect ratio and a free surface on the flow structure in the near-wake behind elliptic cylinders. For each elliptic cylinder, the flow structure was analyzed for various values of the submergence depth of the cylinder beneath the free surface. The flow fields were measured using a single-frame double-exposure PIV (Particle Image Velocimetry) system. For each experimental condition, 350 instantaneous velocity fields were obtained and ensemble-averaged to obtain the mean velocity field and spatial distribution of the mean vorticity statistics. The results show that near-wake can be classified into three typical flow patterns: formation of a Coanda flow, generation of substantial jet-like flow, and attachment of this jet flow to the free surface. The general flow structure observed behind the elliptic cylinders resembles the structure previously reported for a circular cylinder submerged near a free surface. However, the wake width and the angle of downward deflection of the shear layer developed from the lower surface of the elliptic cylinder differ from those observed for a circular cylinder. These trends are enhanced as cylinder aspect ratio is increased. In addition, the free surface distortion is also discussed in the paper. (orig.)

  20. Near-wake flow structure of elliptic cylinders close to a free surface: effect of cylinder aspect ratio

    Science.gov (United States)

    Daichin, K. V.; Lee, Sang Joon

    The flow fields behind elliptic cylinders adjacent to a free surface were investigated experimentally in a circulating water channel. A range of cylinder aspect ratios (AR=2, 3, 4) were considered, while the cross-sectional area of the elliptical cylinder was kept constant. The main objective of this study was to investigate the effect of cylinder aspect ratio and a free surface on the flow structure in the near-wake behind elliptic cylinders. For each elliptic cylinder, the flow structure was analyzed for various values of the submergence depth of the cylinder beneath the free surface. The flow fields were measured using a single-frame double-exposure PIV (Particle Image Velocimetry) system. For each experimental condition, 350 instantaneous velocity fields were obtained and ensemble-averaged to obtain the mean velocity field and spatial distribution of the mean vorticity statistics. The results show that near-wake can be classified into three typical flow patterns: formation of a Coanda flow, generation of substantial jet-like flow, and attachment of this jet flow to the free surface. The general flow structure observed behind the elliptic cylinders resembles the structure previously reported for a circular cylinder submerged near a free surface. However, the wake width and the angle of downward deflection of the shear layer developed from the lower surface of the elliptic cylinder differ from those observed for a circular cylinder. These trends are enhanced as cylinder aspect ratio is increased. In addition, the free surface distortion is also discussed in the paper.

  1. Bending Test of a Variable-Stiffness Fiber-Reinforced Composite Cylinder

    NARCIS (Netherlands)

    Blom, A.W.; Rassaian, M.; Stickler, P.B.; Gürdal, Z.

    2010-01-01

    Two carbon-fiber-reinforced composite cylinders were tested in bending. One cylinder, the baseline cylinder, consisted of 0º, 90º and ±45º plies, whereas the other cylinder, called the variable-stiffness cylinder, contained plies with fiber orientations that varied in the circumferential direction,

  2. Intra-firm Horizontal Knowledge Transfer Management

    Institute of Scientific and Technical Information of China (English)

    WANG Yaowu; WANG Yanhang

    2009-01-01

    Knowledge transfer is widely emphasized as a strategic issue for firm competition. A model for intra-firm horizontal knowledge transfer is proposed to model horizontal knowledge transfer to solve some demerits in current knowledge transfer researches. The concept model of intra-firm horizontal knowledge transfer was described and a framework was provided to define the main components of thetransfer process. Horizontal knowledge transfer is that knowledge is transferred from the source to the same hierarchical level recipients as the target. Horizontal knowledge transfer constitutes a strategic area of knowledge management research. However, little is known about the circumstances under which one particular mechanism is the most appropriate. To address these issues, some significant conclusions are drawn concerning knowledge transfer mechanisms in a real-world setting.

  3. On Vertically Global, Horizontally Local Models for Astrophysical Disks

    Science.gov (United States)

    McNally, Colin P.; Pessah, Martin E.

    2015-10-01

    Disks with a barotropic equilibrium structure, for which the pressure is only a function of the density, rotate on cylinders in the presence of a gravitational potential, so that the angular frequency of such a disk is independent of height. Such disks with barotropic equilibria can be approximately modeled using the shearing box framework, representing a small disk volume with height-independent angular frequency. If the disk is in baroclinic equilibrium, the angular frequency does generally depend on height, and it is thus necessary to go beyond the standard shearing box approach. In this paper, we show that given a global disk model, it is possible to develop approximate models that are local in horizontal planes without an expansion in height with shearing-periodic boundary conditions. We refer to the resulting framework as the vertically global shearing box (VGSB). These models can be non-axisymmetric for globally barotropic equilibria but should be axisymmetric for globally baroclinic equilibria. We provide explicit equations for this VGSB which can be implemented in standard magnetohydrodynamic codes by generalizing the shearing-periodic boundary conditions to allow for a height-dependent angular frequency and shear rate. We also discuss the limitations that result from the radial approximations that are needed in order to impose height-dependent shearing periodic boundary conditions. We illustrate the potential of this framework by studying a vertical shear instability and examining the modes associated with the magnetorotational instability.

  4. Single crystal cylinder transducers for sonar applications

    Science.gov (United States)

    Robinson, Harold; Stevens, Gerald; Buffman, Martin; Powers, James

    2005-04-01

    A segmented cylinder transducer constructed of single crystal lead magnesium niobate-lead titanate (PMN-PT) has been under development at NUWC and EDO Corporation for several years. The purpose of this development was to provide an extremely compact, high power broadband source. By virtue of their extraordinary material properties, ferroelectric single crystals are the ideal transduction material for developing such compact broadband systems. This presentation shall review the evolution of the transducer design as well as present the results of a successful in-water test conducted at NUWC in October of 2003. It shall be shown that design changes intended to eliminate spurious modes limiting the transducer bandwidth first observed in 2002 were successful, resulting in a transducer with a clean frequency response and an effective coupling factor of 0.85. The measured transducer admittance was in nearly exact agreement with theoretical predictions. The NUWC in-water tests demonstrated that the single crystal cylinder achieved an admittance bandwidth (based on the Stansfield criterion) of over 100%, while the tuned power factor was 0.8 or more over 2.5 octaves of frequency. Additionally, the transducer produced 12 dB higher source levels than a similarly sized PZT transducer. [Work sponsored by DARPA.

  5. Terminal project heat convection in thin cylinders

    International Nuclear Information System (INIS)

    Heat convection in thin cylinders and analysis about natural convection for straight vertical plates, and straight vertical cylinders submersed in a fluid are presented some works carry out by different authors in the field of heat transfer. In the part of conduction, deduction of the equation of heat conduction in cylindrical coordinates by means of energy balance in a control volume is presented. Enthalpy and internal energy are used for the outlining of the equation and finally the equation in its vectorial form is obtained. In the convection part development to calculate the Nusselt number for a straight vertical plate by a forces analysis, an energy balance and mass conservation over a control volume is outlined. Several empiric correlations to calculate the Nusselt number and its relations with other dimensionless numbers are presented. In the experimental part the way in which a prototype rode is assembled is presented measurements of temperatures attained in steady state and in free convection for working fluids as air and water are showed in tables. Also graphs of Nusselt numbers obtained in the experimental way through some empiric correlations are showed (Author)

  6. The capillary interaction between two vertical cylinders

    KAUST Repository

    Cooray, Himantha

    2012-06-27

    Particles floating at the surface of a liquid generally deform the liquid surface. Minimizing the energetic cost of these deformations results in an inter-particle force which is usually attractive and causes floating particles to aggregate and form surface clusters. Here we present a numerical method for determining the three-dimensional meniscus around a pair of vertical circular cylinders. This involves the numerical solution of the fully nonlinear Laplace-Young equation using a mesh-free finite difference method. Inter-particle force-separation curves for pairs of vertical cylinders are then calculated for different radii and contact angles. These results are compared with previously published asymptotic and experimental results. For large inter-particle separations and conditions such that the meniscus slope remains small everywhere, good agreement is found between all three approaches (numerical, asymptotic and experimental). This is as expected since the asymptotic results were derived using the linearized Laplace-Young equation. For steeper menisci and smaller inter-particle separations, however, the numerical simulation resolves discrepancies between existing asymptotic and experimental results, demonstrating that this discrepancy was due to the nonlinearity of the Laplace-Young equation. © 2012 IOP Publishing Ltd.

  7. Evidence for horizontal transfer of a recently active Academ transposon.

    Science.gov (United States)

    Zhang, H-H; Shen, Y-H; Xiong, X-M; Han, M-J; Qi, D-W; Zhang, X-G

    2016-06-01

    Horizontal transfer (HT), the exchange of genetic material between species, plays important roles in transposon biology and genome evolution. In this study, we provide the first documented example of a new Academ transposon involved in recent and distant HTs into the genomes of species belonging to seven different orders of insects: Lepidoptera, Hymenoptera, Neuroptera, Embioptera, Dermaptera, Trichoptera and Zoraptera. These results suggest that HT of DNA transposons amongst insects has occurred on a broader scale than previously appreciated. The Academ transposon discovered in the Lepidoptera and parasitic wasps is of particular interest because the intimate association between wasps and their lepidopteran hosts might provide an opportunity for HT of transposons. PMID:26959720

  8. Prediction of External Corrosion for Steel Cylinders--2004 Report

    International Nuclear Information System (INIS)

    Depleted uranium hexafluoride (UF6) is stored in over 60,000 steel cylinders at the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee, at the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and at the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The cylinders range in age from 4 to 53 years. Although when new the cylinders had wall thicknesses specified to within manufacturing tolerances, over the years corrosion has reduced their actual wall thicknesses. The UF6 Cylinder Project is managed by the United States Department of Energy (DOE) to safely maintain the UF6 and the cylinders containing it. This report documents activities that address UF6 Cylinder Project requirements and actions involving forecasting cylinder wall thicknesses. These requirements are delineated in the System Requirements Document (LMES 1997a), and the actions needed to fulfill them are specified in the System Engineering Management Plan (LMES 1997b). The report documents cylinder wall thickness projections based on models fit to ultrasonic thickness (UT) measurement data. UT data is collected at various locations on randomly sampled cylinders. For each cylinder sampled, the minimum UT measurement approximates the actual minimum thickness of the cylinder. Projections of numbers of cylinders expected to fail various thickness criteria are computed from corrosion models relating minimum wall thickness to cylinder age, initial thickness estimates, and cylinder subpopulations defined in terms of plant site, yard, top or bottom storage positions, nominal thickness, etc. In this report, UT data collected during FY03 is combined with UT data collected in earlier years (FY94-FY02), and all of the data is inventoried chronologically and by various subpopulations. The UT data is used to fit models of maximum pit depth and minimum thickness, and the fitted models are used to extrapolate minimum thickness estimates into the future and in turn to compute

  9. Prediction of External Corrosion for Steel Cylinders--2004 Report

    Energy Technology Data Exchange (ETDEWEB)

    Schmoyer, RLS

    2004-07-07

    Depleted uranium hexafluoride (UF{sub 6}) is stored in over 60,000 steel cylinders at the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee, at the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and at the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The cylinders range in age from 4 to 53 years. Although when new the cylinders had wall thicknesses specified to within manufacturing tolerances, over the years corrosion has reduced their actual wall thicknesses. The UF{sub 6} Cylinder Project is managed by the United States Department of Energy (DOE) to safely maintain the UF{sub 6} and the cylinders containing it. This report documents activities that address UF{sub 6} Cylinder Project requirements and actions involving forecasting cylinder wall thicknesses. These requirements are delineated in the System Requirements Document (LMES 1997a), and the actions needed to fulfill them are specified in the System Engineering Management Plan (LMES 1997b). The report documents cylinder wall thickness projections based on models fit to ultrasonic thickness (UT) measurement data. UT data is collected at various locations on randomly sampled cylinders. For each cylinder sampled, the minimum UT measurement approximates the actual minimum thickness of the cylinder. Projections of numbers of cylinders expected to fail various thickness criteria are computed from corrosion models relating minimum wall thickness to cylinder age, initial thickness estimates, and cylinder subpopulations defined in terms of plant site, yard, top or bottom storage positions, nominal thickness, etc. In this report, UT data collected during FY03 is combined with UT data collected in earlier years (FY94-FY02), and all of the data is inventoried chronologically and by various subpopulations. The UT data is used to fit models of maximum pit depth and minimum thickness, and the fitted models are used to extrapolate minimum thickness estimates into the future and in

  10. UF{sub 6} pressure excursions during cylinder heating

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P.G. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    As liquid UF{sub 6} inside a cylinder changes from a liquid to a solid, it forms a porous solid which occupies approximately the same volume as that of the liquid before cooling. Simultaneously as the liquid cools, UF{sub 6} vapor in the cylinder ullage above the liquid desublimes on the upper region of the inner cylinder wall. This solid is a dense, glass-like material which can accumulate to a significant thickness. The thickness of the solid coating on the upper cylinder wall and directly behind the cylinder valve area will vary depending on the conditions during the cooling stage. The amount of time lapsed between UF{sub 6} solidification and UF{sub 6} liquefaction can also affect the UF{sub 6} coating. This is due to the daily ambient heat cycle causing the coating to sublime from the cylinder wall to cooler areas, thus decreasing the thickness. Structural weakening of the dense UF{sub 6} layer also occurs due to cylinder transport vibration and thermal expansion. During cylinder heating, the UF{sub 6} nearest the cylinder wall will liquefy first. As the solid coating behind the cylinder valve begins to liquefy, it results in increased pressure depending upon the available volume for expansion. At the Paducah Gaseous Diffusion Plant (PGDP) during the liquefaction of the UF{sub 6} in cylinders in the UF{sub 6} feed and sampling autoclaves, this pressure increase has resulted in the activation of the systems rupture discs which are rated at 100 pounds per square inch differential.

  11. Refuging rainbow trout selectively exploit flows behind tandem cylinders.

    Science.gov (United States)

    Stewart, William J; Tian, Fang-Bao; Akanyeti, Otar; Walker, Christina J; Liao, James C

    2016-07-15

    Fishes may exploit environmental vortices to save in the cost of locomotion. Previous work has investigated fish refuging behind a single cylinder in current, a behavior termed the Kármán gait. However, current-swept habitats often contain aggregations of physical objects, and it is unclear how the complex hydrodynamics shed from multiple structures affect refuging in fish. To begin to address this, we investigated how the flow fields produced by two D-shaped cylinders arranged in tandem affect the ability of rainbow trout (Oncorhynchus mykiss) to Kármán gait. We altered the spacing of the two cylinders from l/D of 0.7 to 2.7 (where l=downstream spacing of cylinders and D=cylinder diameter) and recorded the kinematics of trout swimming behind the cylinders with high-speed video at Re=10,000-55,000. Digital particle image velocimetry showed that increasing l/D decreased the strength of the vortex street by an average of 53% and decreased the frequency that vortices were shed by ∼20% for all speeds. Trout were able to Kármán gait behind all cylinder treatments despite these differences in the downstream wake; however, they Kármán gaited over twice as often behind closely spaced cylinders (l/D=0.7, 1.1, and 1.5). Computational fluid dynamics simulations show that when cylinders are widely spaced, the upstream cylinder generates a vortex street that interacts destructively with the downstream cylinder, producing weaker, more widely spaced and less-organized vortices that discourage Kármán gaiting. These findings are poised to help predict when fish may seek refuge in natural habitats based on the position and arrangement of stationary objects. PMID:27445401

  12. Comparing standard Bonner spheres and high-sensitivity Bonner cylinders

    International Nuclear Information System (INIS)

    Standard Bonner spheres and proposed high-sensitivity Bonner cylinders were calibrated in a neutron calibration room, using a 252Cf source. The Bonner sphere system consists of 11 polyethylene (PE) spheres of various diameters and 4 extended spheres that comprise embedded metal shells. Similar to the design of Bonner spheres, a set of Bonner cylinders was assembled using a large cylindrical 3He tube as the central probe, which was wrapped using various thicknesses of PE. A layer of lead was employed inside one of the PE cylinders to increase the detection efficiency of high-energy neutrons. The central neutron probe used in the Bonner cylinders exhibited an efficiency of ∼17.9 times higher than that of the Bonner spheres. However, compared with the Bonner spheres, the Bonner cylinders are not fully symmetric in their geometry, exhibiting angular dependence in their responses to incoming neutrons. Using a series of calculations and measurements, this study presents a systematic comparison between Bonner spheres and cylinders in terms of their response functions, detection efficiencies, angular dependences and spectrum unfolding. A high-sensitivity Bonner cylinder spectrometer was developed to facilitate neutron spectrum measurement in low-intensity environments such as the site boundaries of nuclear facilities or accelerators. The proposed spectrometer system comprises 11 cylinders of various PE thicknesses and an extended cylinder with an embedded lead shell. Compared with the standard Bonner spheres, the detection efficiency of the device increased by a factor of >10 because a large 3He tube was employed. However, the Bonner cylinders are not symmetric in their polar angle, and this causes the advantage of isotropic response to be lost. A systematic comparison was conducted between the standard Bonner spheres and the proposed Bonner cylinders, examining their response functions, calibration measurements, angular dependences and spectrum unfolding. (authors)

  13. Identification and Categorization of Horizontally Transferred Genes in Prokaryotic Genomes

    Institute of Scientific and Technical Information of China (English)

    Shuo-Yong SHI; Xiao-Hui CAI; Da-fu DING

    2005-01-01

    Horizontal gene transfer (HGT), a process through which genomes acquire genetic materials from distantly related organisms, is believed to be one of the major forces in prokaryotic genome evolution.However, systematic investigation is still scarce to clarify two basic issues about HGT: (1) what types of genes are transferred; and (2) what influence HGT events over the organization and evolution of biological pathways. Genome-scale investigations of these two issues will advance the systematical understanding of HGT in the context of prokaryotic genome evolution. Having investigated 82 genomes, we constructed an HGT database across broad evolutionary timescales. We identified four function categories containing a high proportion of horizontally transferred genes: cell envelope, energy metabolism, regulatory functions, and transport/binding proteins. Such biased function distribution indicates that HGT is not completely random;instead, it is under high selective pressure, required by function restraints in organisms. Furthermore, we mapped the transferred genes onto the connectivity structure map of organism-specific pathways listed in Kyoto Encyclopedia of Genes and Genomes (KEGG). Our results suggest that recruitment of transferred genes into pathways is also selectively constrained because of the tuned interaction between original pathway members. Pathway organization structures still conserve well through evolution even with the recruitment of horizontally transferred genes. Interestingly, in pathways whose organization were significantly affected by HGT events, the operon-like arrangement of transferred genes was found to be prevalent. Such results suggest that operon plays an essential and directional role in the integration of alien genes into pathways.

  14. The role of vertical shear on the horizontal oceanic dispersion

    Science.gov (United States)

    Lanotte, A. S.; Corrado, R.; Lacorata, G.; Palatella, L.; Pizzigalli, C.; Schipa, I.; Santoleri, R.

    2015-09-01

    The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of South Mediterranean is investigated by means of observative and model data. In-situ current measurements reveal that vertical velocity gradients in the upper mixed layer decorrelate quite fast (∼ 1 day), whereas basin-scale ocean circulation models tend to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion simulated by an eddy-permitting ocean model, like, e.g., the Mediterranean Forecasting System, is mosty affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out; (2) poorly resolved time variability of vertical velocity profiles in the upper layer. For the case study we have analysed, we show that a suitable use of kinematic parameterisations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications.

  15. Angular and linear accelerations of a rolling cylinder acted by an external force

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, V, E-mail: voliveira@isel.ipl.pt [Instituto Superior Engenharia de Lisboa, Avenida Conselheiro Emidio Navarro no 1, 1959-007 Lisboa (Portugal)

    2011-03-15

    The dynamics of a cylinder rolling on a horizontal plane acted on by an external force applied at an arbitrary angle is studied with emphasis on the directions of the acceleration of the centre-of-mass and the angular acceleration of the body. If rolling occurs without slipping, there is a relationship between the directions of these accelerations. If the linear acceleration points to the right, then the angular acceleration is clockwise. On the other hand, if it points to the left, then the angular acceleration is counterclockwise. In contrast, if rolling and slipping occurs, the direction of the linear acceleration does not determine the direction of the angular acceleration. For example, the linear acceleration may point to the right and the angular acceleration clockwise or counterclockwise depending on the external force orientation and point of application.

  16. Prediction of External Corrosion for Steel Cylinders - 1998 Report

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, B.F.

    1998-01-01

    The United States Department of Energy (DOE) currently manages the UF, Cylinder Project. The project was formed to maintain and safely manage depleted uranium hexafluoride (UF{sub 6}) stored in approximately 50,000 carbon steel cylinders. The cylinders located at three DOE sites: the K-25 site at Oak Ridge, Tennessee (K-25); the Paducah Gaseous Diffusion Plant in Paducah, Kentucky (PGDP), and the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The System Requirements Document (SRD) (LMES 1997a) delineates the requirements of the project. The appropriate actions needed to fulfill these requirements are then specified within the System Engineering Management Plan (SEMP) (LMES 1997b). The report presented herein documents activities that in whole or in part satisfy specific requirements and actions stated in the UF{sub 6} Cylinder Project SRD and SEMP with respect to forecasting cylinder conditions. The wall thickness projections made in this report are based on the assumption that the corrosion trends noted will continue. Some activities planned may substantially reduce the rate of corrosion, in which case the results presented here are conservative. The results presented here are intended to supercede and enlarge the scope of those presented previously (Lyon 1995,1996, 1997). In particular, projections are made for thin-walled cylinders (nominal initial thickness 312.5 mils) and thick-walled cylinders (nominal initial thickness 625 mils). In addition, a preliminary analysis is conducted for the minimum thickness at the head/skirt interface for skirted cylinders.

  17. NGSI: Function Requirements for a Cylinder Tracking System

    International Nuclear Information System (INIS)

    While nuclear suppliers currently track uranium hexafluoride (UF6) cylinders in various ways, for their own purposes, industry practices vary significantly. The NNSA Office of Nonproliferation and International Security's Next Generation Safeguards Initiative (NGSI) has begun a 5-year program to investigate the concept of a global monitoring scheme that uniquely identifies and tracks UF6 cylinders. As part of this effort, NGSI's multi-laboratory team has documented the 'life of a UF6 cylinder' and reviewed IAEA practices related to UF6 cylinders. Based on this foundation, this paper examines the functional requirements of a system that would uniquely identify and track UF6 cylinders. There are many considerations for establishing a potential tracking system. Some of these factors include the environmental conditions a cylinder may be expected to be exposed to, where cylinders may be particularly vulnerable to diversion, how such a system may be integrated into the existing flow of commerce, how proprietary data generated in the process may be protected, what a system may require in terms of the existing standard for UF6 cylinder manufacture or modifications to it and what the limiting technology factors may be. It is desirable that a tracking system should provide benefit to industry while imposing as few additional constraints as possible and still meeting IAEA safeguards objectives. This paper includes recommendations for this system and the analysis that generated them.

  18. Turbulent Taylor-Couette flow with stationary inner cylinder

    CERN Document Server

    Ostilla-Monico, Rodolfo; Lohse, Detlef

    2016-01-01

    A series of direct numerical simulations of Taylor-Couette (TC) flow, the flow between two coaxial cylinders, with the outer cylinder rotating and the inner one fixed, were performed. Three cases, with outer cylinder Reynolds numbers $Re_o$ of $Re_o=5.5\\cdot10^4$, $Re_o=1.1\\cdot10^5$ and $Re_o=2.2\\cdot10^5$ were considered. The radius ratio $\\eta=r_i/r_o$ was fixed to $\\eta=0.909$ to mitigate the effects of curvature. The vertical aspect ratio $\\Gamma$ was fixed to $\\Gamma=2.09$. Being linearly stable, outer cylinder rotation TC flow is known to have very different behavior than pure inner cylinder rotation TC flow. Here, we find that the flow nonetheless becomes turbulent, but the torque required to drive the cylinders and level of velocity fluctuations was found to be smaller than those for pure inner cylinder rotation at comparable Reynolds numbers. The mean angular momentum profiles showed a large gradient in the bulk, instead of the constant angular momentum profiles of pure inner cylinder rotation. The ...

  19. Laminar natural convection heat transfer from an inclined cylinder

    International Nuclear Information System (INIS)

    Laminar natural convection heat transfer from the outside surface of a uniformly heated cylinder (constant heat flux condition) was investigated experimentally at different angles of inclination of the cylinder. General equations for the effect of inclination were determined for both the local and the average heat transfer. (author)

  20. Modeling Heat and Mass Transfer from Fabric-Covered Cylinders

    OpenAIRE

    Phillip Gibson

    2009-01-01

    Fabric-covered cylinders are convenient analogs forclothing systems. The geometry is well defined andincludes many of the effects that are important ingarments. Fabric-covered cylinder models are usedin conjunction with laboratory measurements ofmaterial properties to calculate heat and mass transferproperties of clothing under specific conditions ofenvironmental wind speed, temperature, and relativehumidity.

  1. Poiseuille flow-induced vibrations of two cylinders in tandem

    Science.gov (United States)

    Lin, Jianzhong; Jiang, Renjie; Chen, Zhongli; Ku, Xiaoke

    2013-07-01

    Laminar flows past two tandem cylinders which are free to move transversely in a parallel-wall channel were studied numerically by the lattice Boltzmann method. With fixed Reynolds number Re=100, blockage ratio β=1/4 and structural damping ξ=0, the effect of streamwise separation between two cylinders at a range of S/D=[1.1, 10] on the motions of cylinders and fluids was studied for both mass ratios of m(*)=1 and m(*)=0.1. A variety of distinct vibration regimes involving periodic, quasi-periodic and non-periodic vibrations with corresponding flow patterns were observed. A detailed analysis of the vibration amplitudes, vibration frequencies and relative equilibrium positions for both mass ratios demonstrated that as S/D increases, the interaction of the two cylinders first enhances and then reduces. In the strong coupling regime, both cylinders oscillate periodically around the centerline of the channel with large vibration amplitudes and high vibration frequencies. By comparing with the case of an isolated cylinder, a further study indicated that the gap flow plays an important role in such a dynamic system, and the vortex cores formation behind the front cylinder causes the interaction of the cylinders decouple rapidly. Based on the present observations, such a dynamic model system can be considered as a novel type of vortex-induced vibrations (VIV) and is expected to find applications in fluid mixing and heat transfer.

  2. Temperature Profile of a Fluid between Two Rotating Porous Cylinders

    Directory of Open Access Journals (Sweden)

    Bal Krishan

    1970-07-01

    Full Text Available An exact expression for the temperature profile between two concentric rotating porous cylinders has been obtained. The results are presented graphically. For the wide gap, there is a sharp rise in temperature when the ratio between the angular velocities of the outer and the inner cylinders tends to zero.

  3. Vibrations of Circular Cylinders of a Perfectly Conducting Elastic Material

    Directory of Open Access Journals (Sweden)

    K. S. Sarma

    1972-07-01

    Full Text Available The problems of radial vibrations of a long circular solid cylinder with a transverse magnetic field and rotary vibrations of a hollow cylinder with radial magnetic field are solved. The results of the case of an infinite medium with a cylinderical cavity are given. The frequency equation in each case, is solved in particular cases approximately.

  4. Inflation of polymer melts into elliptic and circular cylinders

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Christensen, Jens Horslund; Gøttsche, Søren

    2000-01-01

    A thin sheet (membrane) of the polymeric material is clamped between a Teflon-coated thermostated plate and a thermostated aluminium cylinder. By applying thermostated air through the plate, the polymer membrane deforms into an elliptic or a circular cylinder. The position of the top of the...

  5. Study of Torsional Impact Problem of Orthotropic Hollow Cylinder

    Institute of Scientific and Technical Information of China (English)

    杨华凯; 郝文华; 王熙

    2004-01-01

    A simple integral transform method was presented to solve the torsional impact problem of orthotropic hollow cylinder with mixed boundary condition. The analytical solution for the torsional impact problem of the orthotropic hollow cylinder was got. Some examples were calculated and discussed.

  6. Modeling Heat and Mass Transfer from Fabric-Covered Cylinders

    Directory of Open Access Journals (Sweden)

    Phillip Gibson

    2009-03-01

    Full Text Available Fabric-covered cylinders are convenient analogs forclothing systems. The geometry is well defined andincludes many of the effects that are important ingarments. Fabric-covered cylinder models are usedin conjunction with laboratory measurements ofmaterial properties to calculate heat and mass transferproperties of clothing under specific conditions ofenvironmental wind speed, temperature, and relativehumidity.

  7. An Experiment in Heat Conduction Using Hollow Cylinders

    Science.gov (United States)

    Ortuno, M.; Marquez, A.; Gallego, S.; Neipp, C.; Belendez, A.

    2011-01-01

    An experimental apparatus was designed and built to allow students to carry out heat conduction experiments in hollow cylinders made of different materials, as well as to determine the thermal conductivity of these materials. The evolution of the temperature difference between the inner and outer walls of the cylinder as a function of time is…

  8. 46 CFR 197.338 - Compressed gas cylinders.

    Science.gov (United States)

    2010-10-01

    ... chapter; or (2) 49 CFR 173.34 and 49 CFR part 178, subpart C. ... 46 Shipping 7 2010-10-01 2010-10-01 false Compressed gas cylinders. 197.338 Section 197.338... STANDARDS GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.338 Compressed gas cylinders....

  9. Convection from a Slender Cylinder in a Ventilated Room

    DEFF Research Database (Denmark)

    Heiselberg, Per; Sandberg, Mats

    In this paper the equations, based on integral formulation, for the boundary layer flow in the constant heat flux case and in the constant temperature case have been solved, and both a flat plate and a cylinder solution are presented. Results are compared with measurements carried out in the...... turbulent boundary layer flow along a slender cylinder....

  10. Corotating light cylinders and Alfv\\'en waves

    OpenAIRE

    Gourgouliatos, K. N.; Lynden-Bell, D.

    2010-01-01

    Exact relativistic force free fields with cylindrical symmetry are explored. Such fields are generated in the interstellar gas via their connection to pulsar magnetospheres both inside and outside their light cylinders. The possibility of much enhanced interstellar fields wound on cylinders of Solar system dimensions is discussed but these are most likely unstable.

  11. 76 FR 38697 - High Pressure Steel Cylinders From China

    Science.gov (United States)

    2011-07-01

    ..., 2011 (76 FR 28807). The conference was held in Washington, DC, on June 1, 2011, and all persons who... COMMISSION High Pressure Steel Cylinders From China Determinations On the basis of the record \\1\\ developed... injured by reason of imports from China of high pressure steel cylinders, provided for in subheading...

  12. 77 FR 37712 - High Pressure Steel Cylinders From China

    Science.gov (United States)

    2012-06-22

    ... Commission, Washington, DC, and by publishing the notice in the Federal Register on January 23, 2012 (77 FR... COMMISSION High Pressure Steel Cylinders From China Determinations On the basis of the record \\1\\ developed... imports of high pressure steel cylinders from China, provided for in subheading 7311.00.00 of...

  13. Topology of vortex creation in the cylinder wake

    DEFF Research Database (Denmark)

    Brøns, Morten; Bisgaard, Anders Villefrance

    We analyze the topology of the two-dimensional flow around a circular cylinder at moderate Reynolds numbers in the regime where the vortex wake is created. A normal form for the stream function close to the cylinder is presented and used to predict the streamline pattern both in the steady and the...

  14. Simulation of disordered systems of cylinders. I. geometrical behaviour

    OpenAIRE

    Roux, S; Stauffer, D.; Herrmann, H. J.

    1987-01-01

    We discuss the piling of parallel cylinders with weakly fluctuating radii. The network of contacts consists of self-similar tree-like patterns. The mean expansion of the piling and the distribution of distances between adjacent cylinders are also investigated.

  15. 78 FR 58604 - Safety Advisory: Unauthorized Marking of Compressed Gas Cylinders

    Science.gov (United States)

    2013-09-24

    ... Gas Cylinders AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA), DOT. ACTION... unauthorized marking of high pressure compressed gas cylinders by Beauchesne Fire Equipment located at 21... and special permit cylinders as requalified in accordance with the Hazardous Materials...

  16. 77 FR 1975 - Safety Advisory: Unauthorized Marking of Compressed Gas Cylinders

    Science.gov (United States)

    2012-01-12

    ... Gas Cylinders AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA), DOT. ACTION... cylinders. During a recent investigation, PHMSA determined that between November 2008 and October 2011...'' approximately 7,740 DOT specification cylinders after its authority to requalifiy high pressure...

  17. 77 FR 64590 - Safety Advisory: Unauthorized Marking of Compressed Gas Cylinders

    Science.gov (United States)

    2012-10-22

    ... Gas Cylinders AGENCY: Pipeline and hazardous Materials Safety Administration (PHMSA), DOT. ACTION... unauthorized marking of high pressure compressed gas cylinders by George Welding & Supply Co., Inc. located at... compressed gas cylinders with unauthorized Requalifier Identification Numbers (RIN). In addition,...

  18. Three-dimensionality effects in flow around two tandem cylinders

    Science.gov (United States)

    Papaioannou, Georgios V.; Yue, Dick K. P.; Triantafyllou, Michael S.; Karniadakis, George E.

    2006-07-01

    The flow around two stationary cylinders in tandem arrangement at the laminar and early turbulent regime, (Re {=} 10(2) 10(3) ), is studied using two- and three-dimensional direct numerical simulations. A range of spacings between the cylinders from 1.1 to 5.0 diameters is considered with emphasis on identifying the effects of three-dimensionality and cylinder spacing as well as their coupling. To achieve this, we compare the two-dimensional with corresponding three-dimensional results as well as the tandem cylinder system results with those of a single cylinder. The critical spacing for vortex formation and shedding in the gap region depends on the Reynolds number. This dependence is associated with the formation length and base pressure suction variations of a single cylinder with Reynolds number. This association is useful in explaining some of the discrepancies between the two-dimensional and three-dimensional results. A major effect of three-dimensionality is in the exact value of the critical spacing, resulting in deviations from the two-dimensional predictions for the vorticity fields, the forces on the downstream cylinder, and the shedding frequency of the tandem system. Two-dimensional simulations under-predict the critical spacing, leading to erroneous results for the forces and shedding frequencies over a range of spacings where the flow is qualitatively different. To quantify the three-dimensional effects we first employ enstrophy, decomposed into a primary and a secondary component. The primary component involves the vorticity parallel to the cylinder axis, while the secondary component incorporates the streamwise and transverse components of the vorticity vector. Comparison with the single cylinder case reveals that the presence of the downstream cylinder at spacings lower than the critical value has a stabilizing effect on both the primary and secondary enstrophy. Systematic quantification of three-dimensionalities involves finding measures for the

  19. Optimizing of Culture Conditionin Horizontal Rotating Bioreactor

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    1 IntroductionBioreactor is the most important equipment in tissue engineering. It can mimic the micro-environment of cell growth in vitro. At present, horizontal rotating bioreactor is the most advanced equipment for cell culture in the world. 2 Rotating bioreactors2.1 Working principleThere are two kinds of horizontal rotating bioreactor: HARV(high aspect ratio vessel) and RCCS (rotary cell culture system). It is drived by step motor with horizontal rotation, the culture medium and cell is filled between ...

  20. Horizontal gene transfer and bacterial diversity

    Indian Academy of Sciences (India)

    Chitra Dutta; Archana Pan

    2002-02-01

    Bacterial genomes are extremely dynamic and mosaic in nature. A substantial amount of genetic information is inserted into or deleted from such genomes through the process of horizontal transfer. Through the introduction of novel physiological traits from distantly related organisms, horizontal gene transfer often causes drastic changes in the ecological and pathogenic character of bacterial species and thereby promotes microbial diversification and speciation. This review discusses how the recent influx of complete chromosomal sequences of various microorganisms has allowed for a quantitative assessment of the scope, rate and impact of horizontally transmitted information on microbial evolution.

  1. Two dimensional analysis of low pressure flows in the annulus region between two concentric cylinders.

    Science.gov (United States)

    Al-Kouz, Wael; Alshare, Aiman; Alkhalidi, Ammar; Kiwan, Suhil

    2016-01-01

    A numerical simulation of the steady two-dimensional laminar natural convection heat transfer for the gaseous low-pressure flows in the annulus region between two concentric horizontal cylinders is carried out. This type of flow occurs in "evacuated" solar collectors and in the receivers of the solar parabolic trough collectors. A finite volume code is used to solve the coupled set of governing equations. Boussinesq approximation is utilized to model the buoyancy effect. A correlation for the thermal conductivity ratio (k r = k eff/k) in terms of Knudsen number and the modified Rayleigh number is proposed for Prandtl number (Pr = 0.701). It is found that as Knudsen number increases then the thermal conductivity ratio decreases for a given Rayleigh number. Also, it is shown that the thermal conductivity ratio k r increases as Rayleigh number increases. It appears that there is no consistent trend for varying the dimensionless gap spacing between the inner and the outer cylinder ([Formula: see text]) on the thermal conductivity ratio (k r) for the considered spacing range. PMID:27186493

  2. Oscillatory Magnetohydrodynamic Natural Convection of Liquid Metal between Vertical Coaxial Cylinders

    Directory of Open Access Journals (Sweden)

    Fateh Mebarek-Oudina

    2016-01-01

    Full Text Available A numerical study of oscillatory magnetohydrodynamic (MHD natural convection of liquid metal between vertical coaxial cylinders is carried out. The motivation of this study is to determine the value of the critical Rayleigh number, Racr for two orientations of the magnetic field and different values of the Hartmann number (Harand Haz and aspect ratios A. The inner and outer cylinders are maintained at uniform temperatures, while the horizontal top and bottom walls are thermally insulated. The governing equations are numerically solved using a finite volume method. Comparisons with previous results were performed and found to be in excellent agreement. The numerical results for various governing parameters of the problem are discussed in terms of streamlines, isotherms and Nusselt number in the annuli. The time evolution of velocity, temperature, streamlines and Nusselt number with Racr, Har, Haz, and A is quite interesting. We can control the flow stability and heat transfer rate in varying the aspect ratio, intensity and direction of the magnetic field.

  3. In-Cylinder Flow Through An Internal Combustion (IC) Engine

    Science.gov (United States)

    Khan, Samira; Gibson, Kendrick; Puzinauskas, Paulius; Qi, Yongli

    2008-11-01

    IC engine performance is strongly influenced by large-scale in-cylinder motion developed during the intake process. This work was part of a larger effort to characterize and augment in-cylinder flow structures to improve lean limit and exhaust gas recirculation tolerance. Ultimately the flow structures are to be characterized with unsteady computational fluid dynamics (CFD) calculations. This study provided digital particle image velocimetry (DPIV) flow visualization data under steady conditions to improve the calibration of the CFD work. An engine cylinder head was mounted on a transparent cylinder with a fixed piston. Air was drawn through using a steady flow bench, and DPIV images were obtained from the cylinder. Measurements were made at four suction pressures and four valve lift to diameter ratios for a total of sixteen cases. After initial measurements, intake port modifications were made to enhance tumble. The modifications created more definitive tumble flow.

  4. Expanding cylinder experiments in Cu-2wt%Be

    Science.gov (United States)

    Stirk, Stewart; Winter, Ron

    2011-06-01

    Expanding cylinder techniques are useful methods of investigating dynamic fracture properties since uniform radial strains are achieved at high strain-rates. A gas-gun technique to achieve uniform radial expansion of a cylinder is explored in which the motion of the cylinder is driven by impact of a plastic projectile upon silastomer rubber that partially fills the specimen cylinder. Cylinders of age-hardened copper-beryllium alloy Cu-2wt%Be (TF00 treatment) have been expanded to failure at radial strain-rates in the range 1.2 - 5.7 ×103s-1. The temporal history of fracture activation is captured using high speed photography and modelled using a combined statistics and energy based fragmentation theory. The model is shown to reproduce the crack dynamics and strain-rate dependence reasonably well.

  5. Failure Analysis of a Compressed Natural Gas Storage Cylinder

    International Nuclear Information System (INIS)

    In this work the rupture of an 80 liters capacity CNG storage cylinder installed at a CNG sales station was investigated. It was reported that the cylinder had ruptured only a few months after installation. During the initial investigation, the material of the cylinder was found to be in compliance with the specifications of composition and mechanical properties. However, thorough visual examination of the ruptured surfaces indicated the presence of multiple crack initiation sites within a rusted region on the inner surface of cylinder. This observation indicated the potential for stress corrosion cracking. Further macro-examination of the crack established this feature. Metallographic examination of areas adjacent to the fractured surfaces showed the presence of deep draw-marks almost everywhere and a longitudinal fold of unusual depth. These defects might have acted as stress raisers to assist stress corrosion cracking. It is suggested that the defects were present in the failed cylinder due to improper inspection procedures. (author)

  6. Natural convective heat transfer from short inclined cylinders

    CERN Document Server

    Oosthuizen, Patrick H

    2014-01-01

    Natural Convective Heat Transfer from Short Inclined Cylinders  examines a heat transfer situation of significant, practical importance not adequately dealt with in existing textbooks or in any widely available review papers. Specifically, the book introduces the reader to recent studies of natural convection from short cylinders mounted on a flat insulated base where there is an “exposed” upper surface. The authors considers the effects of the cylinder cross-sectional shape, the cylinder inclination angle, and the length-to-cross sectional size of the cylinder. Both numerical and experimental studies are discussed and correlation equations based on the results of these studies are reviewed. This book is ideal for professionals involved with thermal management and related systems, researchers, and graduate students in the field of natural convective heat transfer, instructors in graduate level courses in convective heat transfer.

  7. Flow resistance of hydraulic cylinder piston ring seal structure

    International Nuclear Information System (INIS)

    According to the control rod hydraulic drive mechanism (CRHDM) and the characteristics of its hydraulic cylinder seal structure, the leaking ways of the hydraulic cylinder piston ring seal were analysed, its theoretical calculation model was built and its flow resistance formula based on the calculation model of differential pressure at the hydraulic cylinder piston ring seal was deduced. By analyzing the results of the CRHDM single cylinder experiment, constants in the formula of the flow resistance were obtained. Under the experimental condition, results from the formula and the experiment tally with each other. The formula and analysis would be helpful for the theoretical analysis and engineering design of the hydraulic cylinder piston ring seal structure. (author)

  8. Method for Making a Carbon-Carbon Cylinder Block

    Science.gov (United States)

    Ransone, Phillip O. (Inventor)

    1997-01-01

    A method for making a lightweight cylinder block composed of carbon-carbon is disclosed. The use of carbon-carbon over conventional materials. such as cast iron or aluminum, reduces the weight of the cylinder block and improves thermal efficiency of the internal combustion reciprocating engine. Due to the negligible coefficient of thermal expansion and unique strength at elevated temperatures of carbon-carbon, the piston-to-cylinder wall clearance can be small, especially when the carbon-carbon cylinder block is used in conjunction with a carbon-carbon piston. Use of the carbon-carbon cylinder block has the effect of reducing the weight of other reciprocating engine components allowing the piston to run at higher speeds and improving specific engine performance.

  9. Transient thermal stress problem for a circumferentially cracked hollow cylinder

    Science.gov (United States)

    Nied, H. F.; Erdogan, F.

    1982-01-01

    The transient thermal stress problem for a hollow elasticity cylinder containing an internal circumferential edge crack is considered. It is assumed that the problem is axisymmetric with regard to the crack geometry and the loading, and that the inertia effects are negligible. The problem is solved for a cylinder which is suddenly cooled from inside. First the transient temperature and stress distributions in an uncracked cylinder are calculated. By using the equal and opposite of this thermal stress as the crack surface traction in the isothermal cylinder the crack problem is then solved and the stress intensity factor is calculated. The numerical results are obtained as a function of the Fourier number tD/b(2) representing the time for various inner-to-outer radius ratios and relative crack depths, where D and b are respectively the coefficient of diffusivity and the outer radius of the cylinder.

  10. The Self-Potential Anomaly Produced by a Subsurface Flow at the Contact of Two Horizontal Layers and Its Quantitative Interpretation

    OpenAIRE

    Georgios Aim. Skianis

    2012-01-01

    In the present paper the problem of a polarized cylinder with a small cross-section, which is located at the contact of two horizontal layers with different resistivities, is studied. Such a polarization geometry simulates the self-potential (SP) field produced by a horizontal flow at the contact between the two layers. First, the expression of the self potential at the space domain is derived, applying the image technique. Then, the expression for the Fourier transform of the SP anomaly is f...

  11. Material point method simulations of fragmenting cylinders

    CERN Document Server

    Banerjee, Biswajit

    2012-01-01

    Most research on the simulation of deformation and failure of metals has been and continues to be performed using the finite element method. However, the issues of mesh entanglement under large deformation, considerable complexity in handling contact, and difficulties encountered while solving large deformation fluid-structure interaction problems have led to the exploration of alternative approaches. The material point method uses Lagrangian solid particles embedded in an Eulerian grid. Particles interact via the grid with other particles in the same body, with other solid bodies, and with fluids. Thus, the three issues mentioned in the context of finite element analysis are circumvented. In this paper, we present simulations of cylinders which fragment due to explosively expanding gases generated by reactions in a high energy material contained inside. The material point method is the numerical method chosen for these simulations discussed in this paper. The plastic deformation of metals is simulated using ...

  12. New guiding elements for hydraulic cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Mustafaev, S.I.

    1984-08-01

    The design is analyzed of plastic or rubber rings used in hydraulic equipment for underground coal mining. The analyses concentrate on rings used in powered supports to guarantee piston positioning parallel to the walls of the cylinder. The following materials used for producing plastic rings are characterized: kaprolon V, polyamide 6, polyamide 12, polyamide 6.10, ATM-2, SFDA, STDA, ATDV and STDG. Ring shape is given in 2 schemes. Effects of ring mechanical and physical properties on operation of the hydraulic system in a powered support section are evaluated: friction, friction increased by pollution of working fluid by dusts, effects of piston wear on its movement and ring position. Effects of guide rings on operation of the MK-97 OKP-70 and M-88 powered supports were investigated under laboratory conditions: leaks of working fluid, piston wear etc. Recommendations are made for use of plastic rings (for guiding and sealing) in powered supports produced in the USSR.

  13. Electrogravitational stability of oscillating streaming fluid cylinder

    International Nuclear Information System (INIS)

    The electrogravitational instability of on oscillating streaming fluid cylinder under the action of the selfgravitating, capillary and electrodynamic forces has been discussed. The model is governed by the Mathieu second order integro-differential equation. Some limiting cases are recovering from the present general one. The capillary force is destabilizing in a small axisymmetric domain 0< x<1 and stabilizing otherwise. In the absence of electric fields, we found that the model is unstable in a small domain while it is selfgravitating stable in all other domains. The presence of the electric field led to the presence of a great number of stable waves. The electric field has a strong stabilizing influence on the selfgravitating instability of the model. The capillary force has a strong destabilizing influence on the selfgravitating instability of the model. Generally, the uniform stream supports the unstable waves, while the oscillating streaming has stability tendency.

  14. Plasmonic corrugated cylinder-cone terahertz probe.

    Science.gov (United States)

    Yao, Haizi; Zhong, Shuncong

    2014-08-01

    The spoof surface plasmon polariton (SPP) effect on the electromagnetic field distribution near the tip of a periodically corrugated metal cylinder-cone probe working at the terahertz regime was studied. We found that radially polarized terahertz radiation could be coupled effectively through a spoof SPP into a surface wave and propagated along the corrugated surface, resulting in more than 20× electric field enhancement near the tip of probe. Multiple resonances caused by the antenna effect were discussed in detail by finite element computation and theoretical analysis of dispersion relation for spoof SPP modes. Moreover, the key figures of merit such as the resonance frequency of the SPP can be flexibly tuned by modifying the geometry of the probe structure, making it attractive for application in an apertureless background-free terahertz near-field microscope. PMID:25121543

  15. Effect of Catalytic Cylinders on Autothermal Reforming of Methane for Hydrogen Production in a Microchamber Reactor

    OpenAIRE

    Yunfei Yan; Hongliang Guo; Li Zhang; Junchen Zhu; Zhongqing Yang; Qiang Tang; Xin Ji

    2014-01-01

    A new multicylinder microchamber reactor is designed on autothermal reforming of methane for hydrogen production, and its performance and thermal behavior, that is, based on the reaction mechanism, is numerically investigated by varying the cylinder radius, cylinder spacing, and cylinder layout. The results show that larger cylinder radius can promote reforming reaction; the mass fraction of methane decreased from 26% to 21% with cylinder radius from 0.25 mm to 0.75 mm; compact cylinder spaci...

  16. Network design for cylinder gas distribution

    Directory of Open Access Journals (Sweden)

    Tejinder Pal Singh

    2015-01-01

    Full Text Available Purpose: Network design of the supply chain is an important and strategic aspect of logistics management. In this paper, we address the network design problem specific to packaged gases (cylinder supply chain. We propose an integrated framework that allows for the determination of the optimal facility locations, the filling plant production capacities, the inventory at plants and hubs, and the number of packages to be routed in primary and secondary transportation. Design/methodology/approach: We formulate the problem as a mixed integer program and then develop a decomposition approach to solve it. We illustrate the proposed framework with numerical examples from real-life packaged gases supply chain. The results show that the decomposition approach is effective in solving a broad range of problem sizes. Findings: The main finding of this paper is that decomposing the network design problem into two sub-problems is very effective to tackle the real-life large scale network design problems occurring in cylinder gas distribution by optimizing strategic and tactical decisions and approximating the operational decisions. We also benchmark the results from the decomposition approach by solving the complete packaged gases network design model for smaller test cases. Originality/value: The main contribution of our work is that it integrates supply chain network design decisions without fixing the fillings plant locations with inventory and resource allocation decisions required at the plants. We also consider the transportation costs for the entire supply chain including the transhipment costs among different facilities by deciding the replenishment frequency.

  17. The Federal Cylinder Project: A Guide to Field Cylinder Collections in Federal Agencies. Volume 8, Early Anthologies.

    Science.gov (United States)

    Lee, Dorothy Sara, Ed; And Others

    This catalog describes wax cylinder recordings of music collected by two pioneers in ethnomusicology. The 101 cylinders in the Benjamin Ives Gilman Collection recorded at the 1893 World's Columbian Exposition in Chicago contain Fijian, Samoan, Uvean, Javanese, Turkish, and Kwakiutl or Vancouver Island Indian music. The Gilman Collection is…

  18. Sensitivity of two-dimensional flow past transversely oscillating cylinder to streamwise cylinder oscillations

    Science.gov (United States)

    Peppa, Sofia; Triantafyllou, George S.

    2016-03-01

    In this paper we study the sensitivity of flow past a transversely oscillating cylinder to streamwise harmonic perturbations. The value of the Reynolds number is equal to 150, for which the flow is two-dimensional. We start with a transversely oscillating cylinder and then impose a small streamwise (in-line) perturbation with a frequency equal to twice the transverse oscillation frequency. The cylinder is thus following an eight-shaped trajectory, which can be traversed in a counter-clockwise or clockwise direction. For low values of the in-line amplitude, we find for the counter-clockwise mode that the power transfer from the fluid to the structure increases with the amplitude of oscillation in the streamwise direction, even though the magnitude of the fluctuations of the forces is decreased. For the clockwise mode of motion we observe the reverse trend, i.e., the power transfer from the fluid to the structure is decreased, even though the magnitude of the fluctuations of the forces is increased. It is shown that the variation of the power transfer in both types of motion is due primarily to the variation of the phase between the transverse oscillation of the cylinder and the vortex lift force as a result of the in-line oscillation. For higher values of the streamwise amplitude, the contribution of the fluctuating drag to the power transfer also becomes important, especially for the counter-clockwise mode. Both modes of oscillation are characterized by the presence of the third harmonic in the spectrum of the lift force as the in-line oscillation is increased and by the appearance of a combination of single vortices on the one side of the wake, and vortex pairs on the other side.

  19. Dynamic monitoring of horizontal gene transfer in soil

    Science.gov (United States)

    Cheng, H. Y.; Masiello, C. A.; Silberg, J. J.; Bennett, G. N.

    2015-12-01

    Soil microbial gene expression underlies microbial behaviors (phenotypes) central to many aspects of C, N, and H2O cycling. However, continuous monitoring of microbial gene expression in soils is challenging because genetically-encoded reporter proteins widely used in the lab are difficult to deploy in soil matrices: for example, green fluorescent protein cannot be easily visualized in soils, even in the lab. To address this problem we have developed a reporter protein that releases small volatile gases. Here, we applied this gas reporter in a proof-of-concept soil experiment, monitoring horizontal gene transfer, a microbial activity that alters microbial genotypes and phenotypes. Horizontal gene transfer is central to bacterial evolution and adaptation and is relevant to problems such as the spread of antibiotic resistance, increasing metal tolerance in superfund sites, and bioremediation capability of bacterial consortia. This process is likely to be impacted by a number of matrix properties not well-represented in the petri dish, such as microscale variations in water, nutrients, and O2, making petri-dish experiments a poor proxy for environmental processes. We built a conjugation system using synthetic biology to demonstrate the use of gas-reporting biosensors in safe, lab-based biogeochemistry experiments, and here we report the use of these sensors to monitor horizontal gene transfer in soils. Our system is based on the F-plasmid conjugation in Escherichia coli. We have found that the gas signal reports on the number of cells that acquire F-plasmids (transconjugants) in a loamy Alfisol collected from Kellogg Biological Station. We will report how a gas signal generated by transconjugants varies with the number of F-plasmid donor and acceptor cells seeded in a soil, soil moisture, and soil O2 levels.

  20. High hydraulic performance in horizontal waterwheels

    Energy Technology Data Exchange (ETDEWEB)

    Pujol, T.; Montoro, L. [Area de Mecnica de Fluids, Escola Politcnica Superior, Universitat de Girona, 17071 Girona, Catalonia (Spain)

    2010-11-15

    Slow rotating waterwheels have been recently proposed as affordable sources of renewable energy in rural areas. In terms of hydraulic efficiency, classical horizontal waterwheels reach values on the order of 50%, being well below those obtained from overshot (71%), waterfall (66%) and, even, undershot (65%) vertical ones. Based on the study of an horizontal waterwheel built prior to 1940s that includes features from both elementary turbines and antique waterwheels, we conclude that horizontal waterwheels may actually reach hydraulic efficiencies as high as 81%. These quantitative results are obtained by analytical approximations and, more important, by numerical integrations through accurate computational fluid dynamics (CFD) simulations. In addition, we show that such a high hydraulic efficiency does not substantially vary when changing the net available head. We suggest that this relevant progress made on improving the efficiency of classical horizontal waterwheels may have implications in future designs of nano/micro hydropower devices. (author)

  1. A methodology to identify the intake charge cylinder-to-cylinder distribution in turbocharged direct injection Diesel engines

    International Nuclear Information System (INIS)

    Exhaust gas recirculation (EGR) is currently the most important NOx emission control system. During the last few years the EGR rate has increased progressively as pollutant emission regulations have become more restrictive. High EGR rate levels have given the effect of the unsuitable EGR and air distribution between cylinders away, which causes undesirable engine behavior. In this sense, the study of the EGR distribution between cylinders achieves high importance. However, despite the fact that the EGR is continuously under study, not many studies have been undertaken to approach its distribution between cylinders. In concordance with the aspects outlined before, the aim of this paper is to propose a methodology that permits us to identify the EGR cylinder-to-cylinder dispersion in a commercial engine. In order to achieve this objective, experimental tests have been combined with both one-dimensional and three-dimensional fluid dynamic models

  2. Horizontal Evaluation: Stimulating social learning among peers

    OpenAIRE

    Thiele, Graham; Devaux, Andre; Velasco, Claudio; Manrique, Kurt

    2006-01-01

    Horizontal evaluation is a flexible evaluation method that combines self-assessment and external review by peers. We have developed and applied this method for use within an Andean regional network that develops new methodologies for research and development (R&D). The involvement of peers neutralizes the lopsided power relations that prevail in traditional external evaluations, creating a more favourable atmosphere for learning and improvement. The central element of a horizontal evaluation ...

  3. HORIZONTAL WELL DRILL-IN FLUIDS

    OpenAIRE

    Nediljka Gaurina-Međimurec

    1998-01-01

    Main objective of horizontal driling is to place a drain-hole for a long distance within the pay zone to enhance productivity or injectivity. In drilling horizontal wells, more serious problems appear than in drilling vertical wells. These problems are: poor hole cleaning, excessive torque and drag, hole filling, pipe stucking, wellbore instability, loss of circulation, formation damage, poor cement job, and difficulties at logging jobs. From that reason, successful drilling and production of...

  4. In Situ Remediation using Horizontal Wells

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Horizontal well technology has been widely used in petroleum and underground utility installation. Since late 1980's, the technology has been adapted for environmental remediation applications. Two general methods in drilling horizontal wells have been used in remediation, trenched and directionally-drilled. The first method involves the excavation of a relatively large diameter borehole, with simultaneous installation of well materials and backfill. The second method, directional drilling, p...

  5. CORRECTED CALCULATION OF HORIZONTAL GATING SYSTEMS

    Directory of Open Access Journals (Sweden)

    I. A. Zayatz

    2015-05-01

    Full Text Available In the course of fulfillment of work the specified calculations of horizontal gating systems for various parts produced in dispensable molds were carried out. The results of work showed that the weight removal value in gating systems fluctuates in big intervals and the specified calculation of horizontal gating systems enables to calculate precisely their weight that allows to calculate quantity of metal in metal charge.

  6. Horizontal Brand Extension and Customer perception

    OpenAIRE

    Khan, Khalid; Janthimapornkij, Rattanawilai

    2011-01-01

    Company use different method for extended their business to different market and to different segment. They use different method; brand extension is one of popular strategy for extension of business. Brand extension does not become successful for every brand, it is very risky. The purpose of this thesis is to study horizontal brand extension and customer perception. We will discuss horizontal brand extension and its two main types franchise brand extension and line extension. Brand extension ...

  7. Emotion recognition (sometimes) depends on horizontal orientations

    OpenAIRE

    Huynh, Carol M; Balas, Benjamin

    2014-01-01

    Face recognition depends critically on horizontal orientations (Goffaux & Dakin, 2010). Face images that lack horizontal features are harder to recognize than those that have that information preserved. Presently, we asked if facial emotional recognition also exhibits this dependency by asking observers to categorize orientation-filtered happy and sad expressions. Furthermore, we aimed to dissociate image-based orientation energy from object-based orientation by rotating images 90-degrees in ...

  8. Mechanical and mathematical models of multi-stage horizontal fracturing strings and their application

    Directory of Open Access Journals (Sweden)

    Zhanghua Lian

    2015-03-01

    Full Text Available Multi-stage SRV fracturing in horizontal wells is a new technology developed at home and abroad in recent years to effectively develop shale gas or low-permeability reservoirs, but on the other hand makes the mechanical environment of fracturing strings more complicated at the same time. In view of this, based on the loading features of tubing strings during the multi-stage fracturing of a horizontal well, mechanical models were established for three working cases of multiple packer setting, open differential-pressure sliding sleeve, and open ball-injection sliding sleeve under a hold-down packer. Moreover, mathematical models were respectively built for the above three cases. According to the Lame formula and Von Mises stress calculation formula for the thick-walled cylinder in the theory of elastic mechanics, a mathematical model was also established to calculate the equivalent stress for tubing string safety evaluation when the fracturing string was under the combined action of inner pressure, external squeezing force and axial stress, and another mathematical model was built for the mechanical strength and safety evaluation of multi-stage fracturing strings. In addition, a practical software was developed for the mechanical safety evaluation of horizontal well multi-stage fracturing strings according to the mathematical model developed for the mechanical calculation of the multi-packer string in horizontal wells. The research results were applied and verified in a gas well of Tahe Oilfield in the Tarim Basin with excellent effects, providing a theoretical basis and a simple and reliable technical means for optimal design and safety evaluation of safe operational parameters of multi-stage fracturing strings in horizontal wells.

  9. The stratification phenomena in the thermal and solutal fields of double-diffusive convection in a circular cylinder

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The structure of double diffusive convection in a circular cylinder cavity has been numerically studied. The numerical results exhibit some new characters of non-horizontal stratifications of thermal and solutal fields: in the stratification state, the isothermal lines near the sidewall are higher than that near the symmetry axis, while the isoconcentration lines near the symmetry axis are relatively high. The mechanism of these non-horizontal stratifications is illustrated by comparing double-diffusive convection with natural convection driven by thermal buoyancy or solutal buoyancy alone. The effects of Lewis number Le and buoyancy ratio N on the non-hor- izontal stratifications of thermal and solutal fields are also investigated. The results show that: at a given time (t = 0.2), with an increase in Le (Le = 0-15), the area influenced by solute diffusion decreases; for isothermal line, the gradients of it initially increase, but it tends to be horizontal at the top of the cavity when the Lewis number is higher than 10. When N varies from 0 to 2, the isoconcentration lines tend to be horizontal while the gradients of isothermal line increase.

  10. Emotion recognition (sometimes) depends on horizontal orientations.

    Science.gov (United States)

    Huynh, Carol M; Balas, Benjamin

    2014-07-01

    Face recognition depends critically on horizontal orientations (Goffaux & Dakin, Frontiers in Psychology, 1(143), 1-14, 2010): Face images that lack horizontal features are harder to recognize than those that have this information preserved. We asked whether facial emotional recognition also exhibits this dependency by asking observers to categorize orientation-filtered happy and sad expressions. Furthermore, we aimed to dissociate image-based orientation energy from object-based orientation by rotating images 90 deg in the picture plane. In our first experiment, we showed that the perception of emotional expression does depend on horizontal orientations, and that object-based orientation constrained performance more than image-based orientation did. In Experiment 2, we showed that mouth openness (i.e., open vs. closed mouths) also influenced the emotion-dependent reliance on horizontal information. Finally, we describe a simple computational analysis that demonstrates that the impact of mouth openness was not predicted by variation in the distribution of orientation energy across horizontal and vertical orientation bands. Overall, our results suggest that emotion recognition largely does depend on horizontal information defined relative to the face, but that this bias is modulated by multiple factors that introduce variation in appearance across and within distinct emotions. PMID:24664854

  11. FORCES ON A NEAR-WALL CIRCULAR CYLINDER

    Institute of Scientific and Technical Information of China (English)

    ZHAN Jing-xia; WANG Jin-jun; ZHANG Pang-feng

    2004-01-01

    The pressure distribution around a near-wall smooth circular cylinder in cross-flow was mainly investigated. The experiment was conducted at the sub-critical Reynolds number ranging from 2.24·104 to 8.94·104,at which the regular vortex separation exists on an isolated circular cylinder. The experimental results indicate that the forces on a circular cylinder near a plane wall are different from those on an isolated circular cylinder. Drag and lift coefficients of a near-wall circular cylinder strongly depend on gap ratio. The increase of gap ratio results in the increase of drag coefficient and the declination of lift coefficient, drag coefficient ranges from 0.5 to 1.0, and lift coefficient from 0.25 to 0 when gap ratio gradually increases from 0 to 1.0, and then the forces tend to be nearly constant with the increase of gap ratio. The attraction between a cylinder and a plane wall, i.e., downward force, occurs when gap ratio lies in certain range. The existence of cylinder changes the pressure gradient on the plane wall, and the influence extends to the location where x/D<-3.0 and x/D>5.0.

  12. FORCE REDUCTION OF FLOW AROUND A SINUSOIDAL WAVY CYLINDER

    Institute of Scientific and Technical Information of China (English)

    ZOU Lin; LIN Yu-feng

    2009-01-01

    A large eddy simulation of cross-flow around a sinusoidal wavy cylinder at Re=3000 was performed and the load cell measurement was introduced for the validation test. The mean flow field and the near wake flow structures were presented and compared with those for a circular cylinder at the same Reynolds number. The mean drag coefficient for the wavy cylinder is smaller than that for a corresponding circular cylinder due to the formation of a longer wake vortex generated by the wavy cylinder. The fluctuating lift coefficient of the wavy cylinder is also greatly reduced. This kind of wavy surface leads to the formation of 3-D free shear layers which are more stable than purely 2-D free shear layers. Such free shear layers only roll up into mature vortices at further downstream position and significantly modify the near wake structures and the pressure distributions around the wavy cylinder. Moreover, the simulations in laminar flow condition were also performed to investigate the effect of Reynolds number on force reduction control.

  13. Flow around two tandem square cylinders near a plane wall

    Science.gov (United States)

    Wang, X. K.; Hao, Z.; Zhang, J.-X.; Tan, S. K.

    2014-10-01

    An experimental study has been conducted to investigate the flow around two identical square cylinders in tandem arrangement and placed near a plane wall at a Reynolds number of 6,300. The inter-cylinder spacing ratio was varied from S * = 0.5 to 6, and the cylinder-to-wall gap ratio from G * = 0.25 to 2. Totally, 42 cases were considered to systematically examine the effects of wall proximity and the mutual interference between the two cylinders in the normalized gap-spacing ( G *- S *) plane. The flow fields were captured using digital particle image velocimetry, in conjunction with measurements of the fluid forces (drag and lift) acting on the downstream cylinder using a piezoelectric load cell. The results show that the flow is highly dependent on the combined values of G * and S *. Categories relating to G * could be broadly classified as small-gap regime ( G * cylinders is suppressed, intermediate-gap regime (0.5 1) where the wall effects become negligible. Similarly, the flow interference between the two cylinders can be divided into three basic categories as a function of S *, namely, shielding regime at S * 3. Variations of force coefficients, amplitude spectra, Strouhal numbers, and Reynolds shear stress with G * and S * are presented to characterize the different flow regimes.

  14. Reutilizing method for UF6 cylinder and device therefor

    International Nuclear Information System (INIS)

    The present invention provides a method of and a device for reutilizing UF6 cylinders after withdrawing UF6 for enrichment of uranium. Namely, UF6 gases are withdrawn for the enrichment of uranium from a UF6 gas charge/discharge port of a cylinder in a cylindrical sealed-type containing vessel filled with UF6. Degraded UF6 formed in this case is reconverted to U3O8 powder. The converted U3O8 powder is filled into the vacant cylinder from the charge/discharge port. With such procedures, since the UF6 cylinder can be utilized again, the amount of large-sized spent UF6 cylinders as radioactive wastes can be reduced. In addition, since the capacity of the UF6 cylinder is larger compared with conventionally used drums, the frequency for the charge of the U3O8 powder is reduced. In addition, since the U3O8 powder is charged into the cylinders of the storage vessel for natural UF6, the U3O8 powder can be stored in existent storage vessels for natural UF6 starting materials. Accordingly, the storage vessel can be utilized effectively. (I.S.)

  15. Stabilization of flow past a cylinder with rounded corners

    Science.gov (United States)

    Zhang, Wei; Samtaney, Ravi

    2015-11-01

    We present results of global linear stability analysis for flow past a cylinder in the low Reynolds number regime Re = 50 - 110 . The four corners of the square cylinder are rounded with a radius of curvature R+ = R / D in which R is the rounding radius and D is the cylinder diameter. Analysis is carried out for R+ = 0 . 00 (square cylinder with sharp corners) to R+ = 0 . 50 (circular cylinder) to investigate its effect on the stability characteristics of the flow. The results reveal that the flow may be stabilized by the rounding of the corners for Re beyond which further rounding has a destabilizing effect on the flow. The stabilization is less effective as the Reynolds number increases and for Re = 110 the square (resp. circular) cylinder has the least (resp. most) unstable growth rate. As R+ increases, the peak of the perturbation kinetic energy growth shifts closer to the cylinder and rapidly damps in the downstream region. The perturbation kinetic energy budget is examined and with the largest contribution due to the transfer of energy from the shear of the base flow. Supported by the KAUST Office of Competitive Research Funds under Award No. URF/1/1394-01.The IBM Blue Gene/P Shaheen at KAUST was utilized for the simulations.

  16. Hygrothermoelastic responses of inhomogeneous piezoelectric and exponentially graded cylinders

    International Nuclear Information System (INIS)

    This paper presents the interaction of electric potentials, electric displacement and elastic deformations. The analytical solution is obtained to describe the hygrothermal responses in inhomogeneous piezoelectric hollow cylinders. The present cylinder is subjected to a both mechanical load and an electric potential. The displacement, stresses and electric potentials in the inhomogeneous cylinders are determined. The material properties coefficients of the present cylinder are assumed to be changed in the radial direction by different distribution forms. Two kinds of numerical application examples are displayed. The hygrothermoelastic response of a piezoelectric inhomogeneous cylinder is presented as the first kind while the hygrothermoelastic response of an exponentially graded composite cylinder is presented as the second kind. The significance of influence of different parameters is investigated. The suitable discussions and final conclusions are made. - Highlights: • The interaction of electric potentials and electric displacement is presented. • The general hygrothermal stress analyses are developed. • Both inhomogeneous piezoelectric and exponentially graded cylinders are examined. • The significance of influence of various parameters is investigated

  17. Adaptive individual-cylinder thermal state control using intake air heating for a GDCI engine

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Gregory T.; Sellnau, Mark C.

    2016-08-09

    A system for a multi-cylinder compression ignition engine includes a plurality of heaters, at least one heater per cylinder, with each heater configured to heat air introduced into a cylinder. Independent control of the heaters is provided on a cylinder-by-cylinder basis. A combustion parameter is determined for combustion in each cylinder of the engine, and control of the heater for that cylinder is based on the value of the combustion parameter for combustion in that cylinder. A method for influencing combustion in a multi-cylinder compression ignition engine, including determining a combustion parameter for combustion taking place in a cylinder of the engine and controlling a heater configured to heat air introduced into that cylinder, is also provided.

  18. Research on Safety Monitoring of Oxygen Cylinder Filling

    Directory of Open Access Journals (Sweden)

    Wang Fangcheng

    2016-01-01

    Full Text Available In recent years, the process of filling oxygen explosion accidents have occurred, causing great casualties and property losses. Great pressure on the safety production of enterprises, resulting in adverse effects on the society. This paper analyzes and summarizes the oxygen bottle filling process types and causes of the accident, found the shortcomings of traditional monitoring methods, and propose a new monitoring methodology, which is based on infrared detection technology oxygen cylinder filling process safety monitoring system. The method can accurately monitor the temperature changes of oxygen cylinder filling process, timely detection of anomalies in the filling process, provide some security for the oxygen cylinder filling operations.

  19. Wake instability issues: From circular cylinders to stalled airfoils

    Science.gov (United States)

    Meneghini, J. R.; Carmo, B. S.; Tsiloufas, S. P.; Gioria, R. S.; Aranha, J. A. P.

    2011-07-01

    Some recent results regarding the global dynamical behaviour of the wake of circular cylinders and airfoils with massive separation are reviewed in this paper. In order to investigate the effect of interference, the three-dimensional instability modes are analysed for the flow around two circular cylinders in tandem. In the same way, the flow around a stalled airfoil is investigated in order to provide a better understanding of the three-dimensional characteristics of wakes forming downstream of a lifting body with massive separation. These results are compared with those found for an isolated cylinder. Some fundamental differences among these flows are discussed.

  20. Oscillations of elastically mounted cylinders in regular waves

    Institute of Scientific and Technical Information of China (English)

    苏炜; 詹杰民; 李毓湘

    2014-01-01

    Under the assumption of potential flow and linear wave theory, a semi-analytic method based on eigenfunciton expansion is proposed to predict the hydrody-namic forces on an array of three bottom-mounted, surface-piercing circular cylinders. The responses of the cylinders induced by wave excitation are determined by the equa-tions of motion coupled with the solutions of the wave radiation and diffraction problems. Experiments for three-cylinder cases are then designed and performed in a wave flume to determine the accuracy of this method for regular waves.

  1. Oscillatory flow about a cylinder pair with unequal radii

    Energy Technology Data Exchange (ETDEWEB)

    Coenen, W, E-mail: wcoenen@ing.uc3m.es [Área de Mecánica de Fluidos, Universidad Carlos III de Madrid, Avenida Universidad 30, E-28911 Leganés, Madrid (Spain)

    2013-10-15

    We consider the oscillating flow about a pair of circular cylinders of unequal diameter. In addition to the relative size of the cylinders, the distance between them can be varied, as can the angle that the undisturbed oscillatory flow makes with the line joining the cylinder centres. For small-amplitude vibrations a time-independent, or steady streaming, motion develops that persists beyond the Stokes layer that forms at the solid boundary. This persistent streaming is considered for large values of a suitably defined streaming Reynolds number. (paper)

  2. Casimir interaction between a plate and a cylinder

    OpenAIRE

    Emig, T.; Jaffe, R. L.; Kardar, M.; Scardicchio, A.

    2006-01-01

    We find the exact Casimir force between a plate and a cylinder, a geometry intermediate between parallel plates, where the force is known exactly, and the plate--sphere, where it is known at large separations. The force has an unexpectedly weak decay \\sim L/(H^3 \\ln(H/R)) at large plate--cylinder separations H (L and R are the cylinder length and radius), due to transverse magnetic modes. Path integral quantization with a partial wave expansion additionally gives a qualitative difference for ...

  3. Scattering of electromagnetic waves by many thin cylinders

    OpenAIRE

    Alexander G. Ramm

    2011-01-01

    Electromagnetic wave scattering by many parallel infinite cylinders is studied asymptotically as $a\\to 0$. Here $a$ is the radius of the cylinders. It is assumed that the points $\\hat{x}_m$ are distributed so that $\\mathcal{N}(\\Delta)=\\frac{1}{a}\\int_{\\Delta}N(x)dx[1+o(1)], $ where $\\mathcal{N}(\\Delta)$ is the number of points $\\hat{x}_m=(x_{m1},x_{m2})$ in an arbitrary open subset of the plane $xoy$, the axes of the cylinders are passing through points $\\hat{x}_m$, these axes are parallel to...

  4. Oscillatory flow about a cylinder pair with unequal radii

    International Nuclear Information System (INIS)

    We consider the oscillating flow about a pair of circular cylinders of unequal diameter. In addition to the relative size of the cylinders, the distance between them can be varied, as can the angle that the undisturbed oscillatory flow makes with the line joining the cylinder centres. For small-amplitude vibrations a time-independent, or steady streaming, motion develops that persists beyond the Stokes layer that forms at the solid boundary. This persistent streaming is considered for large values of a suitably defined streaming Reynolds number. (paper)

  5. Flow instability in flow past O-grooved circular cylinder

    International Nuclear Information System (INIS)

    This study was devoted to elucidating the change in the flow characteristics of a laminar flow past a circular cylinder by modifying the cylinder shape with O-grooves. A numerical analysis was performed in a two-dimensional framework. The cylinder was represented using an immersed boundary method and marker particles on a Cartesian grid system. The number and locations of the O-grooves were the key parameters. An analysis of the flow pattern and flow induced forces was performed at Re = 40 and 50. In addition, we calculated the critical Reynolds number depending on the number of O-grooves and their locations

  6. Inflation of polymer melts into elliptic and circular cylinders

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Christensen, Jens Horslund; Gøttsche, Søren

    2000-01-01

    A thin sheet (membrane) of the polymeric material is clamped between a Teflon-coated thermostated plate and a thermostated aluminium cylinder. By applying thermostated air through the plate, the polymer membrane deforms into an elliptic or a circular cylinder. The position of the top of the...... inflating membrane is detected by fibreoptic sensors positioned in the cylinder. The pressure difference across the inflating membrane is measured as well. Measurements were performed on a polyisobutylene melt. As the deformation in this device is highly non-uniform, the response of the material is modelled...

  7. The characteristics of acoustic emission signal under composite destruction on GFRP gas cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Jee, Hyun Sup; Lee, Jong O; Ju, No Hoe [Korea Institute of Materials Science, Changwon (Korea, Republic of); So, Cheal Ho [Dongsin University, Naju (Korea, Republic of); Lee, Jong Kyu [Dept. of Physics, Bukyong National University, Busan (Korea, Republic of)

    2013-10-15

    This study is investigation of the characteristics for acoustic emission signal generated by destruction on glass fiber bundles and specimen that was machined composite materials surrounding the outside of GFRP cylinder. The Amplitude of acoustic emission signal gets bigger as the cutting angle of knife increases. Accordingly, the number of hits in destruction of composite materials specimen have more in longitudinal direction (longitudinal direction to the glass fiber) than in hoop direction (horizontal direction to the glass fiber) while the amplitude of signals were bigger in hoop direction than longitudinal direction. It was found out that the amplitude of the glass fiber breakage is more than 40 dB and that the amplitude of signal for matrix crack was less than 40 dB because matrix crack signal was not observed when threshold value is 40 dB and matrix crack signal suddenly appeared when threshold value is 32 dB. The slope of the amplitude is related to the acoustic emission source and the slope of the amplitude of the horizontal and vertical directions are 0.16 and 0.08. In particular, The slope of the amplitude of longitudinal direction breakage appear similar to the glass fiber breakage and therefore Acoustic emission source of longitudinal direction breakage is estimated the glass fiber breakage.

  8. The characteristics of acoustic emission signal under composite destruction on GFRP gas cylinder

    International Nuclear Information System (INIS)

    This study is investigation of the characteristics for acoustic emission signal generated by destruction on glass fiber bundles and specimen that was machined composite materials surrounding the outside of GFRP cylinder. The Amplitude of acoustic emission signal gets bigger as the cutting angle of knife increases. Accordingly, the number of hits in destruction of composite materials specimen have more in longitudinal direction (longitudinal direction to the glass fiber) than in hoop direction (horizontal direction to the glass fiber) while the amplitude of signals were bigger in hoop direction than longitudinal direction. It was found out that the amplitude of the glass fiber breakage is more than 40 dB and that the amplitude of signal for matrix crack was less than 40 dB because matrix crack signal was not observed when threshold value is 40 dB and matrix crack signal suddenly appeared when threshold value is 32 dB. The slope of the amplitude is related to the acoustic emission source and the slope of the amplitude of the horizontal and vertical directions are 0.16 and 0.08. In particular, The slope of the amplitude of longitudinal direction breakage appear similar to the glass fiber breakage and therefore Acoustic emission source of longitudinal direction breakage is estimated the glass fiber breakage.

  9. Heat transfer measurements for Stirling machine cylinders

    Science.gov (United States)

    Kornhauser, Alan A.; Kafka, B. C.; Finkbeiner, D. L.; Cantelmi, F. C.

    1994-01-01

    The primary purpose of this study was to measure the effects of inflow-produced heat turbulence on heat transfer in Stirling machine cylinders. A secondary purpose was to provide new experimental information on heat transfer in gas springs without inflow. The apparatus for the experiment consisted of a varying-volume piston-cylinder space connected to a fixed volume space by an orifice. The orifice size could be varied to adjust the level of inflow-produced turbulence, or the orifice plate could be removed completely so as to merge the two spaces into a single gas spring space. Speed, cycle mean pressure, overall volume ratio, and varying volume space clearance ratio could also be adjusted. Volume, pressure in both spaces, and local heat flux at two locations were measured. The pressure and volume measurements were used to calculate area averaged heat flux, heat transfer hysteresis loss, and other heat transfer-related effects. Experiments in the one space arrangement extended the range of previous gas spring tests to lower volume ratio and higher nondimensional speed. The tests corroborated previous results and showed that analytic models for heat transfer and loss based on volume ratio approaching 1 were valid for volume ratios ranging from 1 to 2, a range covering most gas springs in Stirling machines. Data from experiments in the two space arrangement were first analyzed based on lumping the two spaces together and examining total loss and averaged heat transfer as a function of overall nondimensional parameter. Heat transfer and loss were found to be significantly increased by inflow-produced turbulence. These increases could be modeled by appropriate adjustment of empirical coefficients in an existing semi-analytic model. An attempt was made to use an inverse, parameter optimization procedure to find the heat transfer in each of the two spaces. This procedure was successful in retrieving this information from simulated pressure-volume data with artificially

  10. Horizontal alveolar bone loss: A periodontal orphan

    Directory of Open Access Journals (Sweden)

    Jayakumar A

    2010-01-01

    Full Text Available Background: Attempts to successfully regenerate lost alveolar bone have always been a clinician′s dream. Angular defects, at least, have a fairer chance, but the same cannot be said about horizontal bone loss. The purpose of the present study was to evaluate the prevalence of horizontal alveolar bone loss and vertical bone defects in periodontal patients; and later, to correlate it with the treatment modalities available in the literature for horizontal and vertical bone defects. Materials and Methods: The study was conducted in two parts. Part I was the radiographic evaluation of 150 orthopantomographs (OPGs (of patients diagnosed with chronic periodontitis and seeking periodontal care, which were digitized and read using the AutoCAD 2006 software. All the periodontitis-affected teeth were categorized as teeth with vertical defects (if the defect angle was ≤45° and defect depth was ≥3 mm or as having horizontal bone loss. Part II of the study comprised search of the literature on treatment modalities for horizontal and vertical bone loss in four selected periodontal journals. Results: Out of the 150 OPGs studied, 54 (36% OPGs showed one or more vertical defects. Totally, 3,371 teeth were studied, out of which horizontal bone loss was found in 3,107 (92.2% teeth, and vertical defects were found only in 264 (7.8% of the teeth, which was statistically significant (P<.001. Search of the selected journals revealed 477 papers have addressed the treatment modalities for vertical and horizontal types of bone loss specifically. Out of the 477 papers, 461 (96.3% have addressed vertical bone loss, and 18 (3.7% have addressed treatment options for horizontal bone loss. Two papers have addressed both types of bone loss and are included in both categories. Conclusion: Horizontal bone loss is more prevalent than vertical bone loss but has been sidelined by researchers as very few papers have been published on the subject of regenerative treatment

  11. The intracellular bacterium Wolbachia uses parasitoid wasps as phoretic vectors for efficient horizontal transmission.

    Directory of Open Access Journals (Sweden)

    Muhammad Z Ahmed

    2015-02-01

    Full Text Available Facultative bacterial endosymbionts are associated with many arthropods and are primarily transmitted vertically from mother to offspring. However, phylogenetic affiliations suggest that horizontal transmission must also occur. Such horizontal transfer can have important biological and agricultural consequences when endosymbionts increase host fitness. So far horizontal transmission is considered rare and has been difficult to document. Here, we use fluorescence in situ hybridization (FISH and multi locus sequence typing (MLST to reveal a potentially common pathway of horizontal transmission of endosymbionts via parasitoids of insects. We illustrate that the mouthparts and ovipositors of an aphelinid parasitoid become contaminated with Wolbachia when this wasp feeds on or probes Wolbachia-infected Bemisia tabaci AsiaII7, and non-lethal probing of uninfected B. tabaci AsiaII7 nymphs by parasitoids carrying Wolbachia resulted in newly and stably infected B. tabaci matrilines. After they were exposed to infected whitefly, the parasitoids were able to transmit Wolbachia efficiently for the following 48 h. Whitefly infected with Wolbachia by parasitoids had increased survival and reduced development times. Overall, our study provides evidence for the horizontal transmission of Wolbachia between insect hosts by parasitic wasps, and the enhanced survival and reproductive abilities of insect hosts may adversely affect biological control programs.

  12. Effects of gravity modulation on convection in a horizontal annulus

    Energy Technology Data Exchange (ETDEWEB)

    Dyko, Mark P. [Aircraft Braking Systems Corporation, Akron, Ohio (United States). Research and Technology; Vafai, Kambiz [University of California, Riverside, CA (United States). Department of Mechanical Engineering

    2007-01-15

    Convection in the annulus between two horizontal coaxial cylinders resulting from gravity modulation in a microgravity environment is investigated for the first time. The three-dimensional transient equations of fluid motion and heat transfer are solved to study the unsteady flow structures in a large-gap annulus. The gravity fluctuations are shown to induce recirculating flows that reverse direction of rotation in response to the gravitational reversals. Except for a short period of time following flow reversal, at low modulation frequencies the centers of rotation of these flows are below and above the horizontal angular plane when the acceleration acts in the upward and downward directions, respectively, whereas at high frequencies they are above and below this plane. The effects of gravity modulation on development of secondary flows that arise in narrow- and moderate-gap annuli owing to thermal instability are also investigated. It is found that supercritical transverse rolls repeatedly form, dissipate, and re-form in the upper and lower regions of a narrow-gap annulus as a result of the fluctuating gravity field. At the same frequency, the supercritical rolls in a moderate-gap annulus are much slower to develop between flow reversals. The results show that gravity modulation has a stabilizing effect on the secondary flows compared to the case of a constant gravity force, and this effect diminishes with reduction in either frequency or annulus radius ratio R. The effects of frequency on heat transfer in large-, moderate-, and narrow-gap annuli are also studied. It is found that the time-averaged Nusselt number approaches that of pure conduction at high frequencies and increases toward that for terrestrial natural convection as frequency is reduced. As R is decreased, the increase in time-averaged Nusselt number brought about by reducing frequency becomes a smaller percentage of the value for terrestrial natural convection. The results for large-, moderate

  13. Magnetothermoelastic creep analysis of functionally graded cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Loghman, A., E-mail: aloghman@kashanu.ac.i [Department of Mechanical Engineering, Faculty of Engineering, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Ghorbanpour Arani, A.; Amir, S. [Department of Mechanical Engineering, Faculty of Engineering, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Vajedi, A. [Department of Mechanical Engineering, Islamic Azad University, Arak Branch, Arak (Iran, Islamic Republic of)

    2010-07-15

    This paper describes time-dependent creep stress redistribution analysis of a thick-walled FGM cylinder placed in uniform magnetic and temperature fields and subjected to an internal pressure. The material creep, magnetic and mechanical properties through the radial graded direction are assumed to obey the simple power law variation. Total strains are assumed to be the sum of elastic, thermal and creep strains. Creep strains are time, temperature and stress dependent. Using equations of equilibrium, stress-strain and strain-displacement a differential equation, containing creep strains, for displacement is obtained. Ignoring creep strains in this differential equation a closed form solution for the displacement and initial magnetothermoelastic stresses at zero time is presented. Initial magnetothermoelastic stresses are illustrated for different material properties. Using Prandtl-Reuss relation in conjunction with the above differential equation and the Norton's law for the material uniaxial creep constitutive model, the radial displacement rate is obtained and then the radial and circumferential creep stress rates are calculated. Creep stress rates are plotted against dimensionless radius for different material properties. Using creep stress rates, stress redistributions are calculated iteratively using magnetothermoelastic stresses as initial values for stress redistributions. It has been found that radial stress redistributions are not significant for different material properties, however major redistributions occur for circumferential and effective stresses.

  14. Cylinder supplied ammonia scrubber testing in IDMS

    International Nuclear Information System (INIS)

    This report summarizes the results of the off-line testing the Integrated DWPF Melter System (IDMS) ammonia scrubbers using ammonia supplied from cylinders. Three additional tests with ammonia are planned to verify the data collected during off-line testing. Operation of the ammonia scrubber during IDMS SRAT and SME processing will be completed during the next IDMS run. The Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) scrubbers were successful in removing ammonia from the vapor stream to achieve ammonia vapor concentrations far below the 10 ppM vapor exit design basis. In most of the tests, the ammonia concentration in the vapor exit was lower than the detection limit of the analyzers so results are generally reported as <0.05 parts per million (ppM). During SRAT scrubber testing, the ammonia concentration was no higher than 2 ppM and during SME testing the ammonia concentration was no higher than 0.05 m

  15. Cylinder Block Fixture for Mistake Proofing.

    Directory of Open Access Journals (Sweden)

    L.B.Raut

    2014-10-01

    Full Text Available The project idea basically developed from trunnion tables which are one type of fixture having ability to rotate about its axis and able to fix the component at any angle, so there is no requirement of angle plate and sine plates, drilling process is also computer controlled so no guide bush is required, So robust design for extra rigidity, flexibility and simple to use. In this project task is difficult as design rotary cage type fixture for component like cylinder block, which is heavy of 76 kg. it is not possible to rotate or handle component manually and proceed on them to make this process accident proof and automated for this purpose we are designing a rotary cage which rotate 360 degree and allow indexing to process on the component. Processes are to be operated on the component are drilling tapping and air blow washing ,Since drilling don’t need clamping here components self weight will enough to carry drilling force and tapping force coming through power tools. Therefore, rotary cage type fixture is critical importance.

  16. Nonlinear Fracture Mechanics and Plasticity of the Split Cylinder Test

    DEFF Research Database (Denmark)

    Olesen, John Forbes; Østergaard, Lennart; Stang, Henrik

    2006-01-01

    properties. This implies that the linear elastic interpretation of the ultimate splitting force in term of the uniaxial tensile strength of the material is only valid for special situations, e.g. for very large cylinders. Furthermore, the numerical analysis suggests that the split cylinder test is not well......The split cylinder testis subjected to an analysis combining nonlinear fracture mechanics and plasticity. The fictitious crack model is applied for the analysis of splitting tensile fracture, and the Mohr-Coulomb yield criterion is adopted for modelling the compressive crushing/sliding failure. Two...... demonstrates the influence of varying geometry or constitutive properties. For a split cylinder test in load control it is shown how the ultimate load is either plasticity dominated or fracture mechanics dominated. The transition between the two modes is related to changes in geometry or constitutive...

  17. Wave propagation in coated cylinders with reference to fretting fatigue

    Indian Academy of Sciences (India)

    M Ramesh; Satish V Kailas; K R Y Simha

    2008-06-01

    Fretting fatigue is the phenomenon of crack initiation due to dynamic contact loading, a situation which is commonly encountered in mechanical couplings subjected to vibration. The study of fretting fatigue in high frequency regime has gained importance in recent years. However the stress wave effects at high frequency y loading is scanty in the literature. The objective of present investigation is to study stress wave propagation in cylinders with reference to high frequency fretting. The case of a coated cylinder is considered since coating is often provided to improve tribological properties of the component. Rule of mixtures is proposed to understand the dispersion phenomenon in coated or layered cylinder knowing the dispersion relation for the cases of homogeneous cylinders made of coating and substrate materials separately. The possibility of stress wave propagation at the interface with a particular phase velocity without dispersion is also discussed. Results are given for two different thicknesses of coating.

  18. Prediction of External Corrosion for Steel Cylinders 2003 Report

    Energy Technology Data Exchange (ETDEWEB)

    Schmoyer, RLS

    2003-09-24

    Depleted uranium hexafluoride (UF{sub 6}) is stored in over 60,000 steel cylinders at the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee, at the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and at the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The cylinders range in age from six to 52 years. Although when new the cylinders had wall thicknesses specified to within manufacturing tolerances, over the years corrosion has reduced their actual wall thicknesses. The UF{sub 6} Cylinder Project is managed by the United States Department of Energy (DOE) to safely maintain the UF{sub 6} and the cylinders containing it. The requirements of the Project are delineated in the System Requirements Document (LMES 1997a), and the actions needed to fulfill those requirements are specified in the System Engineering Management Plan (LMES 1997b). This report documents activities that address requirements and actions involving forecasting cylinder wall thicknesses. Wall thickness forecasts are based on models fit to ultrasonic thickness (UT) measurement data. First, UT data collected during FY02 is combined with UT data collected in earlier years (FY92-FY01), and all of the data is inventoried chronologically and by various subpopulations. Next, the data is used to model either maximum pit depth or minimum thickness as a function of cylinder age, subpopulation (e.g., PGDP G-yard, bottom-row cylinders), and initial thickness estimates. The fitted models are then used to extrapolate minimum thickness estimates into the future and to compute estimates of numbers of cylinders expected to fail various thickness criteria. A model evaluation is performed comparing UT measurements made in FY02 with model-fitted projections based only on data collected before FY02. The FY02 UT data, entered into the corrosion model database and not available for the previous edition of this report (Schmoyer and Lyon 2002), consists of thickness measurements of 48

  19. Two circular cylinders in cross-flow: A review

    Science.gov (United States)

    Sumner, D.

    2010-08-01

    Pairs of circular cylinders immersed in a steady cross-flow are encountered in many engineering applications. The cylinders may be arranged in tandem, side-by-side, or staggered configurations. Wake and proximity interference effects, which are determined primarily by the longitudinal and transverse spacing between the cylinders, and also by the Reynolds number, have a strong influence on the flow patterns, aerodynamic forces, vortex shedding, and other parameters. This paper reviews the current understanding of the flow around two “infinite” circular cylinders of equal diameter immersed in a steady cross-flow, with a focus on the near-wake flow patterns, Reynolds number effects, intermediate wake structure and behaviour, and the general trends in the measurements of the aerodynamic force coefficients and Strouhal numbers. A primary focus is on the key experimental and numerical studies that have appeared since the last major review of this subject more than 20 years ago.

  20. Kinetic resistance of hydraulic cylinder piston ring seal structure

    International Nuclear Information System (INIS)

    According to the step motion of single cylinder for Control Rod Hydraulic Drive Mechanism (CRHDM) and the characteristics of the hydraulic cylinder piston ring seal structure, the source of kinetic resistance during step motion process was analyzed, the theoretical model of the dynamic step motion process was built and the value of kinetic resistance based on the results of the control rod hydraulic drive mechanism single cylinder experiment was deduced. By analyzing the relationship between kinetic resistance and the dynamic parameters of the step motion process including the pressure and the velocity of the inner cylinder, calculation model of the kinetic resistance during the step motion process was obtained. The displacement curve inferred from this model agrees with the experimental data. This model would be helpful for the dynamic simulation of the step motion process and the stress analysis of the control rod hydraulic drive mechanism. (authors)

  1. Development Of A Portal Monitor For UF6 Cylinder Verification

    International Nuclear Information System (INIS)

    International Atomic Energy Agency (IAEA) inspectors currently perform periodic inspections at uranium enrichment plants to verify UF6 cylinder enrichment declarations. Measurements are performed with handheld high-resolution sensors on a sampling of cylinders taken to be representative of the facility's operations. As additional enrichment plans come online to support the expansion of nuclear power, reducing person-days of inspection will take on greater importance. Pacific Northwest National Laboratory (PNNL) is developing a concept to automate the verification of enrichment plant cylinders to enable 100% product-cylinder verification and potentially, mass-balance calculations on the facility as a whole (by also measuring feed and tails cylinders). The Automated Cylinder Enrichment Verification System (ACEVS) would be located at key measurement points and will positively identify each cylinder, measure its mass and enrichment, store the data along with operator inputs in a secure database, and maintain continuity of knowledge on measured cylinders until IAEA inspector arrival. Given the potential for reduced inspector presence, the operational and manpower-reduction benefits of the portal concept are clear. However, it is necessary to assess whether the cylinder portal concept can meet, or potentially improve upon, today's U-235 enrichment assay performance. PNNL's ACEVS concept utilizes sensors that could be operated in an unattended mode: moderated He-3 neutron detectors and large NaI(Tl) scintillators for gamma-ray spectroscopy. The medium-resolution NaI(Tl) scintillators are a sacrifice in energy resolution but do provide high collection efficiency for signatures above 1 MeV. The He-3/NaI sensor combination allows the exploitation of additional, more-penetrating signatures than those currently utilized: Neutrons produced from F-19(a,n) reactions (spawned primarily from U-234 alpha emission) and high-energy gamma rays (extending up to 10 MeV) induced by

  2. NONLINEAR FREE SURFACE ACTION WITH AN ARRAY OF VERTICAL CYLINDERS

    Institute of Scientific and Technical Information of China (English)

    HUANG J. B.

    2004-01-01

    Nonlinear diffraction of regular waves by an array of bottom-seated circular cylinders is investigated in frequency domain, based on a Stokes expansion approach. A complete semi-analytical solution is developed which allows an efficient evaluation of the second-order potentials in the entire fluid domain, and the wave forces on the structure. Expressions are derived for the second-order potential in the vicinity of individual cylinders. These expressions have a simple form, thus providing an effective means for investigating the wave enhancement due to nonlinear interactions with multiple cylinders. Based on the present method, the wave run-up and free-surface elevations around an array of two, three and four cylinders are investigated numerically.

  3. Motion of an inclined cylinder on an inclined plane

    Science.gov (United States)

    Cross, Rod

    2015-09-01

    We consider in this paper the motion of an inclined cylinder on an inclined plane. At low inclined plane angles, the cylinder rolls without slipping across the incline, in a direction perpendicular to its long axis. At steeper angles, long cylinders follow a straight line path in a direction that veers away from the low angle path. Short cylinders follow a curved path. These effects are described in terms of a transition from rolling to sliding as the incline angle is increased. The results help to explain why a vehicle normally turns in the direction that the wheels are pointing and why a vehicle can veer away from that direction on a slippery surface.

  4. The torqued cylinder and Levi-Civita’s metric

    International Nuclear Information System (INIS)

    When a static cylindrical system is subjected to equal and opposite torques top and bottom it transports angular momentum along its axis. The external metric of this static system can be transformed to Levi-Civita’s form by using helical coordinates. This gives the external metric of a static cylinder three dimensionless parameters corresponding to the mass per unit length, the total stress along the cylinder, and the total torque. The external vacuum metric of a spherical system is characterised by its mass alone. How many parameters characterise the external metric of a general stationary cylindrical system? Leaving aside the radius of the cylinder which defines the scale we find that there are five parameters, the three above mentioned, to which should be added the momentum along the cylinder per unit length and the angular momentum per unit length. We show how to transform Levi-Civita’s one parameter metric to include all five. (fast track communications)

  5. Guided flux motion and Faraday induction in hollow superconducting cylinders

    International Nuclear Information System (INIS)

    Guided flux motion and Faraday induction effects were observed in two hollow cylinders of superconducting niobium in an effort to understand the origin of flux flow voltages in superconductors. Calculations are in excellent agreement with experimental results

  6. Synthesis of antenna arrays radiation patterns on random geometry cylinders

    OpenAIRE

    Gabriel'yan, D. D.; Kalchenko, O. V.

    2007-01-01

    Synthesis algorithm for gain-phase radiation patterns formed by linear electrical vibrators antenna arrays located on random geometry cylinders is discussed. The results of numerical calculations are presented.

  7. HORIZONTAL WELL DRILL-IN FLUIDS

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    1998-12-01

    Full Text Available Main objective of horizontal driling is to place a drain-hole for a long distance within the pay zone to enhance productivity or injectivity. In drilling horizontal wells, more serious problems appear than in drilling vertical wells. These problems are: poor hole cleaning, excessive torque and drag, hole filling, pipe stucking, wellbore instability, loss of circulation, formation damage, poor cement job, and difficulties at logging jobs. From that reason, successful drilling and production of horizontal well depends largely on the fluid used during drilling and completion phases. Several new fluids, that fulfill some or all of required properties (hole cleaning, cutting suspension, good lubrication, and relative low formation damage, are presented in this paper.

  8. Horizontal stirring in the global ocean

    CERN Document Server

    Hernández-Carrasco, I; Hernández-García, E; Turiel, A

    2011-01-01

    Horizontal mixing and the distribution of coherent structures in the global ocean are analyzed using Finite-Size Lyapunov Exponents (FSLE), computed for the surface velocity field derived from the Ocean general circulation model For the Earth Simulator (OFES). FSLEs measure horizontal stirring and dispersion; additionally, the transport barriers which organize the oceanic flow can roughly be identified with the ridges of the FSLE field. We have performed a detailed statistical study, particularizing for the behaviour of the two hemispheres and different ocean basins. The computed Probability Distributions Functions (PDFs) of FSLE are broad and asymmetric. Horizontal mixing is generally more active in the northern hemisphere than in the southern one. Nevertheless the Southern Ocean is the most active ocean, and the Pacific the less active one. A striking result is that the main currents can be classified in two 'activity classes': Western Boundary Currents, which have broad PDFs with large FSLE values, and Eas...

  9. Diffuser Augmented Horizontal Axis Tidal Current Turbines

    Directory of Open Access Journals (Sweden)

    Nasir Mehmood

    2012-09-01

    Full Text Available The renewal energy technologies are increasingly popular to ensure future energy sustenance and address environmental issues. The tides are enormous and consistent untapped resource of renewable energy. The growing interest in exploring tidal energy has compelling reasons such as security and diversity of supply, intermittent but predictable and limited social and environmental impacts. The tidal energy industry is undergoing an increasing shift towards diffuser augmented turbines. The reason is the higher power output of diffuser augmented turbines compared to conventional open turbines. The purpose of this study is to present a comprehensive review of diffuser augmented horizontal axis tidal current turbines. The components, relative advantages, limitations and design parameters of diffuser augmented horizontal axis tidal current turbines are presented in detail. CFD simulation of NACA 0016 airfoil is carried out to explore its potential for designing a diffuser. The core issues associated with diffuser augmented horizontal axis tidal current turbines are also discussed.

  10. Holographic Charge Excitations on Horizontal Boundary

    CERN Document Server

    Hotta, M

    2002-01-01

    We argue that states with nontrivial horizontal charges of BTZ black hole can be excited by ordinary falling matter including Hawking radiation. The matter effect does not break the integrability condition of the charges on the horizon. Thus we are able to trace the proccesses in which the matter imprints the information on the horizon by use of the charged states. It is naturally expected that in the thermal equilibrium with the Hawking radiation the black hole wanders ergodically through different horizontal states due to thermal fluctuation of incoming matter. This fact strengthens plausibility of the basic part of Carlip's idea. We also discuss some aspects of the quantum horizontal symmetry and conjecture how the precise black hole entropy will be given from our point of view.

  11. 49 CFR 173.301a - Additional general requirements for shipment of specification cylinders.

    Science.gov (United States)

    2010-10-01

    ... specification cylinders. 173.301a Section 173.301a Transportation Other Regulations Relating to Transportation....301a Additional general requirements for shipment of specification cylinders. (a) General. The... gases in specification cylinders. (b) Authorized cylinders not marked with a service pressure....

  12. 76 FR 71124 - Safety Advisory: Unauthorized Marking of Compressed Gas Cylinders

    Science.gov (United States)

    2011-11-16

    ... Gas Cylinders AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA), DOT. ACTION: Safety Advisory Notice. SUMMARY: An undetermined number of high pressure DOT specification cylinders were... filling these cylinders, a person must verify that the cylinder has been properly requalified by...

  13. 30 CFR 75.1106-4 - Use of liquefied and nonliquefied compressed gas cylinders; general requirements.

    Science.gov (United States)

    2010-07-01

    ... gas cylinders; general requirements. 75.1106-4 Section 75.1106-4 Mineral Resources MINE SAFETY AND...-UNDERGROUND COAL MINES Fire Protection § 75.1106-4 Use of liquefied and nonliquefied compressed gas cylinders... compressed gas unit, consisting of one oxygen cylinder and one additional gas cylinder, shall be used...

  14. The Friction of Vehicle Brake Tandem Master Cylinder

    Science.gov (United States)

    Kao, M. J.; Chang, H.; Tsung, T. T.; Lin, H. M.

    2006-10-01

    The behaviour of an elastomeric seal for vehicle brake Tandem master cylinder is measured and analyzed in temperature and brake fluids changed. Working conditions are simulated for different piston rod velocity and cylinder supply pressure, in temperature rising, brakefluid boundary and Nanoaluminum oxide brakefluid oxide brakefluid lubrication. The result shows that Nanoaluminum oxide brakefluid with its ball shape can highly reduce friction coefficient to avoid seal excessive wear and reduce slick slip in brake applications.

  15. Numerical Analysis and Optimization of Engine Cylinder Fins of Varying

    OpenAIRE

    Saravanan

    2014-01-01

    The main aim of the project is to analyze the thermal properties by varying geometry, material and thickness of cylinder fins. Parametric models of cylinder with fins have been developed to predict the transient thermal behavior. The models are created by varying the geometry, rectangular, circular and curved shaped fins and also by varying thickness of the fins. The 3D modeling software used is Pro/Engineer.The analysis is done using ANSYS. Presently Material used for manufac...

  16. Radiation dose rates from UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Friend, P.J. [Urenco, Capenhurst (United Kingdom)

    1991-12-31

    This paper describes the results of many studies, both theoretical and experimental, which have been carried out by Urenco over the last 15 years into radiation dose rates from uranium hexafluoride (UF{sub 6}) cylinders. The contents of the cylinder, its history, and the geometry all affect the radiation dose rate. These factors are all examined in detail. Actual and predicted dose rates are compared with levels permitted by IAEA transport regulations.

  17. The simplified material parameter equation for elliptical cylinder cloaks

    Institute of Scientific and Technical Information of China (English)

    Ma Hua; Qu Shao-Bo; Xu Zhuo; Zhang Jie-Qiu; Wang Jia-Fu

    2009-01-01

    We simplify the material parameter equation for elliptical cylinder cloaks under transverse-electric and transverse-magnetic modcis, respectively, and confirm these simplified equations by numerical simulations. As a result, the number of the component parameters is reduced from three to two, which simplifies the design of meta-materials and thus opens up the possibility of achieving elliptical cylinder cloaks in an easy way.

  18. Nonlinear Front Evolution of Hydrodynamic Chemical Waves in Vertical Cylinders

    OpenAIRE

    Wilder, J. W.; Vasquez, D.A.; Edwards, Boyd F.

    1997-01-01

    The nonlinear stability of three-dimensional reaction-diffusion fronts in vertical cylinders is considered using the viscous hydrodynamic fluid equations in the limit of infinite thermal diffusivity. A nonlinear front evolution equation is presented and used to examine the transition from nonaxisymmetric to axisymmetric convection observed in experiments performed in cylinders. Comparisons with experiments show excellent agreement in both the shape and speed of the front.

  19. The Friction of Vehicle Brake Tandem Master Cylinder

    International Nuclear Information System (INIS)

    The behaviour of an elastomeric seal for vehicle brake Tandem master cylinder is measured and analyzed in temperature and brake fluids changed. Working conditions are simulated for different piston rod velocity and cylinder supply pressure, in temperature rising, brakefluid boundary and Nanoaluminum oxide brakefluid oxide brakefluid lubrication. The result shows that Nanoaluminum oxide brakefluid with its ball shape can highly reduce friction coefficient to avoid seal excessive wear and reduce slick slip in brake applications

  20. Simulation of Flow Around Cylinder Actuated by DBD Plasma

    Science.gov (United States)

    Wang, Yuling; Gao, Chao; Wu, Bin; Hu, Xu

    2016-07-01

    The electric-static body force model is obtained by solving Maxwell's electromagnetic equations. Based on the electro-static model, numerical modeling of flow around a cylinder with a dielectric barrier discharge (DBD) plasma effect is also presented. The flow streamlines between the numerical simulation and the particle image velocimetry (PIV) experiment are consistent. According to the numerical simulation, DBD plasma can reduce the drag coefficient and change the vortex shedding frequencies of flow around the cylinder.

  1. Flow Simulation in Engine Cylinder with Spring Mesh

    OpenAIRE

    M. H. Shojaeefard; A. R. Noorpoor

    2008-01-01

    This investigation presents results from numerical simulation of the air flow in Spark Ignition Engine (SI engine) cylinder. Accurate modeling of the flow in cylinder is a key part of successful combustion simulation. The most usual numerical method in Computational Fluid Dynamics (CFD) is finite volume. In this investigation an important, common fluid flow patterns in CFD simulations, namely, Tumble motion typical in automotive engines and RNG k-ε turbulence model were used. The air flo...

  2. Mathematic modelling of circular cylinder deformation under inner grouwth

    Directory of Open Access Journals (Sweden)

    A. V. Siasiev

    2009-09-01

    Full Text Available A task on the intensive deformed state (IDS of a viscoelastic declivous cylinder, which is grown under the action of inner pressure, is considered. The process of continuous increase takes a place on an internal radius so, that a radius and pressure change on set to the given law. The special case of linear law of creeping is considered, and also numeral results are presented as the graphs of temporal dependence of tensions and moving for different points of cylinder.

  3. Cylinder expansion test and gas gun experiment comparison

    Energy Technology Data Exchange (ETDEWEB)

    Harrier, Danielle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-30

    This is a summer internship presentation by the Hydro Working Group at Los Alamos National Laboratory (LANL) and goes into detail about their cylinder expansion test and gas gun experiment comparison. Specifically, the gas gun experiment is detailed along with applications, the cylinder expansion test is detailed along with applications, there is a comparison of the methods with pros and cons and limitations listed, the summer project is detailed, and future work is talked about.

  4. Longitudinal Weld Land Buckling in Compression-Loaded Orthogrid Cylinders

    Science.gov (United States)

    Thornburgh, Robert P.; Hilburger, Mark W.

    2010-01-01

    Large stiffened cylinders used in launch vehicles (LV), such as the Space Shuttle External Tank, are manufactured by welding multiple curved panel sections into complete cylinders. The effects of the axial weld lands between the panel sections on the buckling load were studied, along with the interaction between the acreage stiffener arrangement and the weld land geometry. This document contains the results of the studies.

  5. Prebuckling, Buckling, and Postbuckling Response of Segmented Circular Composite Cylinders

    OpenAIRE

    Riddick, Jaret Cleveland

    2001-01-01

    Discussed is a numerical and experimental characterization of the response of small-scale fiber-reinforced composite cylinders constructed to represent a fuselage design whereby the crown and keel consist of one laminate stacking sequence and the two sides consist of another laminate stacking sequence. This construction is referred to as a segmented cylinder. The response to uniform axial endshortening is discussed. Numerical solutions for the nonlinear prebuckling, buckling, and postbuckling...

  6. Circular Cylinders by Four or Five Points in Space

    OpenAIRE

    Devillers, Olivier; Mourrain, Bernard; Preparata, Franco ,; Preparata, Franco P.; Trebuchet, Philippe

    2002-01-01

    We are interested in computing effectively cylinders through 5 points, and in other problems involved in metrology. In particular, we consider the cylinders through 4 points with a fix radius and with extremal radius. For these different problems, we give bounds on the number of solutions and exemples show that these bounds are optimal. Finally, we describe two algebraic methods which can be used here to solve efficiently these problems and some experimentation results.

  7. Stirring by multi-cylinder in potential flow

    OpenAIRE

    Lin, Zhi; Zhang, Yuanzhao

    2014-01-01

    We consider the enhanced mixing due to multiple cylinders organised in schools moving synchronously in a potential flow. Here simple interactions between cylinders are modelled by the method of image doublets. This is an extension to Thiffeault \\& Childress's work [\\emph{Physics Letters A} \\textbf{374}, 3487 (2010)] where fluid particle displacements due to non-interacting swimmers were analysed to produce an effective diffusivity that may have a significant impact in ocean mixing. Our result...

  8. Motion of multiple cylinders in potential flow of ideal fluid

    OpenAIRE

    Kharlamov, Alexander A.; Filip, P.(Joint Institute for Nuclear Research, Dubna, 141 980, Russia)

    2011-01-01

    The flow field past multiple arbitrarily moving cylinders is calculated using a generalisation of the conventional images method. The flow is presented by a flow from an infinite set of dipoles. For calculation purposes the infinite series must be, however, truncated. The kinetic energy of fluid is presented as a sum over all modelling dipoles. A rather good convergence of the method is observed. However, if the distances between any cylinders tend to zero, the method fails in zones close to ...

  9. On circular Cylinders by Four or Five Points in Space

    OpenAIRE

    Devillers, Olivier; Mourrain, Bernard; Preparata, Franco ,; Trebuchet, Philippe

    2001-01-01

    We are interested in computing effectively cylinders through 5 points, and in other problems involved in metrology. In particular, we consider the cylinders through 4 points with a fix radius and with extremal radius. For these different problems, we give bounds on the number of solutions and exemples show that these bounds are optimal. Finally, we describe two algebraic methods which can be used here to solve efficiently these problems and some experimentation results.

  10. Homology cylinders and sutured manifolds for homologically fibered knots

    OpenAIRE

    Goda, Hiroshi; Sakasai, Takuya

    2008-01-01

    Sutured manifolds defined by Gabai are useful in the geometrical study of knots and 3-dimensional manifolds. On the other hand, homology cylinders are in an important position in the recent theory of homology cobordisms of surfaces and finite-type invariants. We study a relationship between them by focusing on sutured manifolds associated with a special class of knots which we call {\\it homologically fibered knots}. Then we use invariants of homology cylinders to give applications to...

  11. Relaxation of Thick-Walled Cylinders and Spheres

    DEFF Research Database (Denmark)

    Saabye Ottosen, N.

    1982-01-01

    Using the nonlinear creep law proposed by Soderberg, (1936) closed-form solutions are derived for the relaxation of incompressible thick-walled spheres and cylinders in plane strain. These solutions involve series expressions which, however, converge very quickly. By simply ignoring these series...... expressions, extremely simple approximate solutions are obtained. Despite their simplicity these approximations possess an accuracy that is superior to approximations currently in use. Finally, several physical aspects related to the relaxation of cylinders and spheres are discussed...

  12. Kinematics investigations of cylinders rolling down a ramp using tracker

    Science.gov (United States)

    Prima, Eka Cahya; Mawaddah, Menurseto; Winarno, Nanang; Sriwulan, Wiwin

    2016-02-01

    Nowadays, students' exploration as well as students' interaction in the application stage of learning cycle can be improved by directly model real-world objects based on Newton's Law using Open Source Physics (OSP) computer-modeling tools. In a case of studying an object rolling down a ramp, a traditional experiment method commonly uses a ticker tape sliding through a ticker timer. However, some kinematics parameters such as the instantaneous acceleration and the instantaneous speed of object cannot be investigated directly. By using the Tracker video analysis method, all kinematics parameters of cylinders rolling down a ramp can be investigated by direct visual inspection. The result shows that (1) there are no relations of cylinders' mass as well as cylinders' radius towards their kinetics parameters. (2) Excluding acceleration data, the speed and position as function of time follow the theory. (3) The acceleration data are in the random order, but their trend-lines closely fit the theory with 0.15% error. (4) The decrease of acceleration implicitly occurs due to the air friction acting on the cylinder during rolling down. (5) The cylinder's inertial moment constant has been obtained experimentally with 3.00% error. (6) The ramp angle linearly influences the cylinders' acceleration with 2.36% error. This research implied that the program can be further applied to physics educational purposes.

  13. Regimes of flow induced vibration for tandem, tethered cylinders

    Science.gov (United States)

    Nave, Gary; Stremler, Mark

    2015-11-01

    In the wake of a bluff body, there are a number of dynamic response regimes that exist for a trailing bluff body depending on spacing, structural restoring forces, and the mass-damping parameter m* ζ . For tandem cylinders with low values of m* ζ , two such regimes of motion are Gap Flow Switching and Wake Induced Vibration. In this study, we consider the dynamics of a single degree-of-freedom rigid cylinder in the wake of another in these regimes for a variety of center-to-center cylinder spacings (3-5 diameters) and Reynolds numbers (4,000-11,000). The system consists of a trailing cylinder constrained to a circular arc around a fixed leading cylinder, which, for small angle displacements, bears a close resemblance to the transversely oscillating cylinders found more commonly in existing literature. From experiments on this system, we compare and contrast the dynamic response within these two regimes. Our results show sustained oscillations in the absence of a structural restoring force in all cases, providing experimental support for the wake stiffness assumption, which is based on the mean lift toward the center line of flow.

  14. Bank Angle of a V-Type 12-Cylinder Engine

    Science.gov (United States)

    Ito, Norio; Nakagawa, Akihito; Kitamura, Ryuji

    As the automobile engine advances towards higher performance and higher power, the increase in displacement and the number of cylinders in the engine has led to larger engines. As a result, the need for rigidity countermeasures and reductions in size and weight have brought about the switch from in-line type engines to V-type engines. Currently, most of the V-type automobile engines produced have six or eight cylinders, and some large passenger cars produced in Europe and America have V-type engines with 10 or 12 cylinders. The bank angles of engines in these passenger are almost fixed based on the cylinder number. Therefore, the form of the V-type engine is limited according to the number of cylinders. The present study examines the bank angle of a V-12 engine by performing a detailed analysis of the relationship between the cylinder arrangement and the exciting moment. The goal of the present study is to find a bank angle that has as of yet not been applied to the V-type engine so that the layouts of the absorption and exhaust systems, as well as the attached apparatuses, can be reconfigured.

  15. The Interaction Vortex Flow Around Two Bluff Cylinders

    Directory of Open Access Journals (Sweden)

    Hirao K.

    2013-04-01

    Full Text Available In this study, the interaction vortex flow features around a pair of parallel arranged bluff cylinders were observed by visualizing water flow experiment at the range of the gap ratio G/d=0~3. It was obtained that the result of established wind tunnel test and the result of this water tank test agreed about the characteristics of vortex shedding when varying the distance of circular cylinder gap. The flow pattern and vortex shedding frequency of another type bluff cylinder (triangular and square cylinder were also investigated. As a result of the experiment, it was shown that the flow pattern of wake flow was divided into three kinds (coupled vortex streets, biased gap flow and single vortex street regardless of the cylinder section shape and cylinder size. Then, the region of the appearance of flow pattern was shown about each case. In the case where two each other independent vortex streets were formed, three typical flow patterns of vortex formation (in-phase coupled vortex streets, out-of-phase coupled vortex streets and complication coupled vortex streets were observed. It was known that three configuration of vortex formation appear intermittently and alternatively.

  16. Fourth international seminar on horizontal steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Tuomisto, H. [ed.] [IVO Group, Vantaa (Finland); Purhonen, H. [ed.] [VTT, Espoo (Finland); Kouhia, V. [ed.] [Lappeenranta Univ. of Technology (Finland)

    1997-12-31

    The general objective of the International Seminars of Horizontal Steam Generator Modelling has been the improvement in understanding of realistic thermal hydraulic behaviour of the generators when performing safety analyses for VVER reactors. The main topics presented in the fourth seminar were: thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the VVER safety technology. The number of participants, representing designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organizations, universities and regulatory authorities, was 70 from 10 countries.

  17. Causes and characteristics of horizontal positional nystagmus.

    Science.gov (United States)

    Lechner, Corinna; Taylor, Rachael L; Todd, Chris; Macdougall, Hamish; Yavor, Robbie; Halmagyi, G Michael; Welgampola, Miriam S

    2014-05-01

    Direction changing horizontal positional nystagmus can be observed in a variety of central and peripheral vestibular disorders. We tested sixty subjects with horizontal positional nystagmus and vertigo on the Epley Omniax(®) rotator. Monocular video recordings were performed with the right or left ear down, in the supine and prone positions. Nystagmus slow-phase velocity (SPV) was plotted as a function of time. Thirty-one subjects diagnosed with horizontal canalolithiasis had paroxysmal horizontal geotropic nystagmus with the affected ear down (onset 0.8 ± 1 s, range 0-4.9 s, duration 11.7-47.9 s, peak SPV 79 ± 67°/s). The SPV peaked at 5-20 s and declined to 0 by 60 s; at 40 s from onset, the average SPV was 1.8 % of the peak. Nine subjects diagnosed with cupulolithiasis had persistent apogeotropic horizontal nystagmus (onset 0.7 ± 1.4 s, range 0-4.3 s). Peak SPV was 54.2 ± 31.8°/s and 26.6 ± 12.2°/s with unaffected and affected ears down, respectively. At 40 s, the average SPV had decayed to only 81 % (unaffected ear down) and 65 % (affected ear down) of the peak. Twenty subjects were diagnosed with disorders other than benign positional vertigo (BPV) [vestibular migraine (VM), Ménière's Disease, vestibular schwannoma, unilateral or bilateral peripheral vestibular loss]. Subjects with VM (n = 13) had persistent geotropic or apogeotropic horizontal nystagmus. On average, at 40 s from nystagmus onset, the SPV was 61 % of the peak. Two patients with Ménière's Disease had persistent apogeotropic horizontal nystagmus; the peak SPV at 40 s ranged between 28.6 and 49.5 % of the peak. Symptomatic horizontal positional nystagmus can be observed in canalolithiasis, cupulolithiasis and diverse central and peripheral vestibulopathies; its temporal and intensity profile could be helpful in the separation of these entities. PMID:24676938

  18. Fourth international seminar on horizontal steam generators

    International Nuclear Information System (INIS)

    The general objective of the International Seminars of Horizontal Steam Generator Modelling has been the improvement in understanding of realistic thermal hydraulic behaviour of the generators when performing safety analyses for VVER reactors. The main topics presented in the fourth seminar were: thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the VVER safety technology. The number of participants, representing designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organizations, universities and regulatory authorities, was 70 from 10 countries

  19. Frictional properties of lubrication greases with the addition of nickel nanoparticles in pneumatic cylinder

    Science.gov (United States)

    Chang, Ho; Lan, Chou-Wei; Guo, Jia-Bin

    2011-12-01

    This paper studies the influence of addition of 100 nm diameter nickel nano-particles on the friction properties of synthetic grease (Li base, VG100) in pneumatic cylinder. The friction force test of pneumatic cylinder equipment measures the frictional force between seal and cylinder bore in pneumatic cylinders. The lubricants with addition of nickel nano-particles were used for lubricating the contact interface between seal and cylinder bore. The friction force test equipment employ a load cell force sensor to measure the friction force between seals and cylinder bores. Results obtained from experimental tests are compared to determine the friction force between seals and cylinder bore in pneumatic cylinders. The study leads to the conclusion that the addition of nickel nano-particles to synthetic grease results in a decrease in friction force between seals and cylinder bores in pneumatic cylinder. This tribological behavior is closely related to the deposition of nano-particles on the rubbing surfaces

  20. Adaptive individual-cylinder thermal state control using piston cooling for a GDCI engine

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Gregory T; Husted, Harry L; Sellnau, Mark C

    2015-04-07

    A system for a multi-cylinder compression ignition engine includes a plurality of nozzles, at least one nozzle per cylinder, with each nozzle configured to spray oil onto the bottom side of a piston of the engine to cool that piston. Independent control of the oil spray from the nozzles is provided on a cylinder-by-cylinder basis. A combustion parameter is determined for combustion in each cylinder of the engine, and control of the oil spray onto the piston in that cylinder is based on the value of the combustion parameter for combustion in that cylinder. A method for influencing combustion in a multi-cylinder engine, including determining a combustion parameter for combustion taking place in in a cylinder of the engine and controlling an oil spray targeted onto the bottom of a piston disposed in that cylinder is also presented.

  1. Fuel Efficiency Mapping of a 2014 6-Cylinder GM EcoTec 4.3L Engine with Cylinder Deactivation

    Science.gov (United States)

    This paper describes the method and test results of the engine dyno portion of the benchmarking test results including engine fuel consumption maps showing the effects of cylinder deactivation engine technology.

  2. ENVIRONMENTAL IMPACT EVALUATION: AN INVESTIGATION OF CYLINDER ASSEMBLY AND CYLINDER HEAD ASSEMBLY OF ENGINE GROUP

    Directory of Open Access Journals (Sweden)

    Ms. SUMAN SHARMA

    2012-07-01

    Full Text Available Despite today’s green marketing campaigns, no engineering product is truly environmentally designed. It is necessary to know the environmental impact of a product, so that it can be developed further for the environmental design. The environmental impact of products and processes has become a key issue now. Industries have started to assess the impact of their activities on the environment. Therefore the need to assess the environmental impact of various products has been felt. The work has been carried out using the life cycle assessment. The LCA is a means of deriving a quantitativeevaluation of environmental impact of product and thereby refining product quality and characteristics. It has been carried out for the two sub-assemblies of the engine group of two-wheeler ‘Activa’. Study investigates the environmental impact assessment for two main subassemblies ‘cylinder assembly’ and ‘cylinder head assembly’ for three main life cycle stages under the ‘’cradle-to-gate’. The ecotoxicity and human toxicity have very large impact as compared to global warming, acidification and ozone depletion in both cases. The results about the selected sub assemblies of two wheelers can support the designers to develop the engine group with improved environmental impact.

  3. Modelling and numerical simulation of vortex induced vibrations of single cylinder or cylinder arrays

    International Nuclear Information System (INIS)

    This research thesis fits into the frame of researches achieved in the nuclear field in order to optimize the predictive abilities of sizing models of nuclear plant components. It more precisely addresses the modelling of the action exerted by the flowing fluid and the induced feedback by the structure dynamics. The objective is herein to investigate the interaction between the turbulence at the wall vicinity and the effects of non-conservative and potentially destabilizing unsteady coupling. The peculiar case of a single cylinder in infinite environment, and submitted to a transverse flow, is studied statically and then dynamically. The influence of flow regimes on dynamic response is characterized, and the quantification of fluid-structure interaction energy is assessed. The author then addresses the case of an array of cylinders, and highlights the contribution of three-dimensional macro-simulations for the analysis of flow-induced structure vibrations in subcritical regime within a High Performance Calculation (HPC) framework, and the interest of a CFD/CSM (computational fluid dynamics/computational structure mechanics) coupling in the case of turbulent flows in an industrial environment

  4. How many oxygen cylinders do you need to take on transport? A nomogram for cylinder size and duration

    OpenAIRE

    Lutman, D; Petros, A J

    2006-01-01

    When undertaking patient retrieval, it is important to take adequate supplies of oxygen to ensure patient safety. Oxygen can be delivered via a flowmeter into a facemask or used to drive pneumatic ventilators. Given the lack of space in the back of an ambulance or helicopter, the numbers of cylinders that can be taken is limited, hence the number needed to complete the journey must be carefully calculated prior to embarking. We have produced nomograms to predict how many oxygen cylinders will...

  5. Biological Threats

    Science.gov (United States)

    ... Workplace Plans School Emergency Plans Main Content Biological Threats Biological agents are organisms or toxins that can ... for Disease Control and Prevention . Before a Biological Threat Unlike an explosion, a biological attack may or ...

  6. Results of ultrasonic testing evaluations on UF{sub 6} storage cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Lykins, M.L.

    1997-02-01

    The three site cylinder management program is responsible for the safe storage of the DOE owned UF{sub 6} storage cylinders at PORTS, PGDP and at the K-25 site. To ensure the safe storage of the UF{sub 6} in the cylinders, the structural integrity of the cylinders must be evaluated. This report represents the latest cylinder integrity investigation that utilized wall thickness evaluations to identify thinning due to atmospheric exposure.

  7. Cues for localization in the horizontal plane

    DEFF Research Database (Denmark)

    Jeppesen, Jakob; Møller, Henrik

    2005-01-01

    manipulated in HRTFs used for binaural synthesis of sound in the horizontal plane. The manipulation of cues resulted in HRTFs with cues ranging from correct combinations of spectral information and ITDs to combinations with severely conflicting cues. Both the ITD and the spectral information seem to be...

  8. Stabilities of Parallel Flow and Horizontal Convection

    OpenAIRE

    Sun, Liang

    2009-01-01

    In the first part, the stability of two-dimensional parallel flow is discussed. A more restrictively general stability criterion for inviscid parallel flow is obtained analytically. In the second part, we report the numerical simulations of the partial-penetrating flow in horizontal convection within a squire cavity tank at high Rayleigh numbers $10^7

  9. Comparing cost and performance of horizontal wells

    Energy Technology Data Exchange (ETDEWEB)

    Pocovi, A.S.; Gustavino, L.L. (Gerencia de Mineria y Geologica de Exploracion, YPF (AR)); Pozzo, A.; Musmarra, J.A. (Gerencia General de Exploracion, YPF, Buenos Aires (AR))

    1991-02-01

    Argentina's state oil company, YPF, was forced through technical and economic constraints to undertake a four-well pilot horizontal drilling program in its Neuquen fields. This article discusses techniques used, the results and costs, and compares them to costs incurred by the area's original vertical wells.

  10. Terrain slugging in near horizontal oilwells

    OpenAIRE

    Fozard, J.

    2001-01-01

    In this thesis we consider the problem of terrain slugging in near horizontal producing wells. We formulate a simple model for stratified two-phase flow, and consider the linear stability of steady states. We then study the possibility of the formation of roll waves, and make a tentative attempt at a resolution of the problem.

  11. Horizontal Axis Levitron--A Physics Demonstration

    Science.gov (United States)

    Michaelis, Max M.

    2014-01-01

    After a brief history of the Levitron, the first horizontal axis Levitron is reported. Because it is easy to operate, it lends itself to educational physics experiments and analogies. Precession and nutation are visualized by reflecting the beam from a laser pointer off the "spignet". Precession is fundamental to nuclear magnetic…

  12. Buoyancy Driven Natural Ventilation through Horizontal Openings

    DEFF Research Database (Denmark)

    Heiselberg, Per; Li, Zhigang

    2009-01-01

    An experimental study of the phenomenon of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. The measurements were made for opening ratios L/D ranging from 0.027 to 4.455, where L and D are the length of the opening and...

  13. Third international seminar on horizontal steam generators

    International Nuclear Information System (INIS)

    The Third International Seminar on Horizontal Steam Generators held on October 18-20, 1994 in Lappeenranta, consisted of six sessions dealing with the topics: thermal hydraulic experiments and analyses, primary collector integrity, management of primary-to-secondary leakage accidents, feedwater collector replacement and discussion of VVER-440 steam generator safety issues

  14. Evaluation of horizontal magnification on panoramic images

    Directory of Open Access Journals (Sweden)

    Maryam Raoof

    2013-01-01

    Full Text Available Aims: This study evaluated the horizontal magnification of images taken from adults and pediatrics with PM 2002 CC Planmeca analogue machine. Materials and Methods: A series of 120 panoramic radiographs were obtained of 60 adults and 60 pediatrics. For all patients, negative impressions were used to make positive casts of the teeth. A caliper was used to measure the maximum mesiodistal length of the buccal surface of all teeth except canines on both casts and radiographs. The horizontal magnification factor was calculated for incisor, premolar, and molar regions by dividing the values obtained from the casts by the values obtained from the radiographs. Statistical Analysis: Independent t-test and one-way analysis of variance (ANOVA were used. Results: The results indicated that with regard to adults, maxillary and mandibular incisor regions, unlike the other two sessions, didn′t show significant difference of the mean magnification of horizontal dimension (P = 0.5. In pediatrics, the comparison between mean magnification factors of all subgroups showed significant difference (P < 0.0001. Despite the adults′ radiographs, the results of pediatrics′ radiographs showed significantly higher magnification than the index listed by the manufacturer of the radiographic machine used. Conclusion: The present study results point to the fact that PM 2002 CC Proline panoramic machine makes possible precise measurements on radiographs of adults′ jaws in the horizontal dimension.

  15. Third international seminar on horizontal steam generators

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    The Third International Seminar on Horizontal Steam Generators held on October 18-20, 1994 in Lappeenranta, consisted of six sessions dealing with the topics: thermal hydraulic experiments and analyses, primary collector integrity, management of primary-to-secondary leakage accidents, feedwater collector replacement and discussion of VVER-440 steam generator safety issues.

  16. Parametric study for horizontal steam generator modelling

    Energy Technology Data Exchange (ETDEWEB)

    Ovtcharova, I. [Energoproekt, Sofia (Bulgaria)

    1995-12-31

    In the presentation some of the calculated results of horizontal steam generator PGV - 440 modelling with RELAP5/Mod3 are described. Two nodalization schemes have been used with different components in the steam dome. A study of parameters variation on the steam generator work and calculated results is made in cases with separator and branch.

  17. Flow mapping for ESS horizontal target

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Y.; Kikura, H.; Taishi, T. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Flow behaviour for ESS horizontal target is studied experimentally using two dimensional water model. A velocity field of stationary flow in reaction zone has been obtained. Three dimensional effect was also studied as a spanwise flow structure. (author) 3 figs., 3 refs.

  18. Horizontally separated 1-in-1 crossing insertions

    Energy Technology Data Exchange (ETDEWEB)

    Syphers, M.J. [Fermi National Accelerator Lab., Batavia, IL (United States)

    1985-10-01

    Previous to this workshop, realistic lattices have been developed for vertically separated l-in-l (e.g., D.E. Johnson, A.A. Garren) and 2-in-1 (e.g., S. Heifets) magnets as well as for horizontally separated 2-in-l magnets (e.g., SSC RDS). Bringing together the widely separated ({approximately}60-70 cm) beams in a reasonable length of tunnel and keeping the dispersion zero at the interaction point has been difficult in the vertical l-in-l case. Most designs have required spacial 2-in-1 quadrupoles near the interaction point where the beams are separated by 15 cm or less. It is not clear that such magnets, as dictated by some of these lattice designs, can easily be built. The purpose of this exercise is to provide a crossing insertion for a realistic lattice which involves horizontally separated l-in-l magnets. The following horizontal crossing insertions, which incorporate the dispersion suppressors and phase trombones into the major arcs, need no special 2-in-1 magnets near the interaction point. The dispersion at the IP created by the horizontal crossing can be cancelled by the dispersion suppressor and one set of triplets.

  19. Rallian "equivalent" cylinders reconsidered: comparisons with literal compartments.

    Science.gov (United States)

    Goldfinger, M D

    2005-06-01

    In Rall's "equivalent" cylinder morphological-to-electrical transformation, neuronal arborizations are reduced to single unbranched core-conductors. The conventional assumption that such an "equivalent" reconstructs the electrical properties of the fibers it represents was tested directly; electrical properties and responses of "equivalent" cylinders were compared with those of their literal branch constituents for fibers with a single symmetrical bifurcation. The numerical solution methods were validated independently by their accurate reconstruction of the responses of an analog circuit configured with compartmental architecture to solve the cable equation for passive fibers with a symmetrical bifurcation. In passive fibers, "equivalent" cylinders misestimated the spatial distribution of voltage amplitudes and steady-state input resistance, partly due to the lack of axial current bifurcation. In active fibers with a single propagating action potential, the spatial distributions of point-to-point conduction velocity values (measured in meters/second) for a literal branch point differed significantly from those of their "equivalent" cylinders. "Equivalent" cylinders also underestimated the diameter-dependent delay in propagation through the branch point and branches, due to the larger "equivalent" diameter. Corrections to the "equivalent" cylinder did not reconcile differences between "equivalent" and literal models. However, "equivalent" and literal branch fibers had the same (a) steady-state resistance "looking into" an isolated symmetrical branch point and (b) geometry-independent point-to-point propagation velocity when measured in space constants per millisecond except within +/-1 space constant from the geometrical inhomogeneity. In summary, Rall's "equivalent" cylinders did not accurately reconstruct all passive or active electrophysiological properties and responses of their literal compartments. For the modeling of individual neurons, the requirement of

  20. Prediction of external corrosion for steel storage cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, B.F.

    1997-02-01

    The US Department of Energy (DOE) currently manages the UF{sub 6} Cylinder Program (the program). The program was formed to address the depleted-uranium hexafluoride (UF{sub 6}) stored in approximately 50,000 carbon steel cylinders. The cylinders are located at three DOE sites: the K-25 site (K-25) at Oak Ridge, Tennessee; the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, Kentucky, and the Portsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio. The System Requirements Document (SRD) (LMES 1996a) delineates the requirements of the program. The appropriate actions needed to fulfill these requirements are then specified within the System Engineering Management Plan (SEMP) (LMES 1996b). The report presented herein documents activities that in whole or in part satisfy specific requirements and actions stated in the UF{sub 6} Cylinder Program SRD and SEMP with respect to forecasting cylinder conditions. The wall thickness projections made in this report are based on the assumption that the corrosion trends noted will continue. Some activities planned may substantially reduce the rate of corrosion, in which case the results presented here are conservative. The results presented here are intended to supersede those presented previously, as the quality of several of the datasets has improved.