Wall roughness induces asymptotic ultimate turbulence
Zhu, Xiaojue; Verschoof, Ruben Adriaan; Bakhuis, Dennis; Huisman, Sander Gerard; Verzicco, Roberto; Sun, Chao; Lohse, Detlef
2018-01-01
Turbulence governs the transport of heat, mass and momentum on multiple scales. In real-world applications, wall-bounded turbulence typically involves surfaces that are rough; however, characterizing and understanding the effects of wall roughness on turbulence remains a challenge. Here, by
Wall roughness induces asymptotic ultimate turbulence
Zhu, Xiaojue; Verschoof, Ruben A.; Bakhuis, Dennis; Huisman, Sander G.; Verzicco, Roberto; Sun, Chao; Lohse, Detlef
2018-04-01
Turbulence governs the transport of heat, mass and momentum on multiple scales. In real-world applications, wall-bounded turbulence typically involves surfaces that are rough; however, characterizing and understanding the effects of wall roughness on turbulence remains a challenge. Here, by combining extensive experiments and numerical simulations, we examine the paradigmatic Taylor-Couette system, which describes the closed flow between two independently rotating coaxial cylinders. We show how wall roughness greatly enhances the overall transport properties and the corresponding scaling exponents associated with wall-bounded turbulence. We reveal that if only one of the walls is rough, the bulk velocity is slaved to the rough side, due to the much stronger coupling to that wall by the detaching flow structures. If both walls are rough, the viscosity dependence is eliminated, giving rise to asymptotic ultimate turbulence—the upper limit of transport—the existence of which was predicted more than 50 years ago. In this limit, the scaling laws can be extrapolated to arbitrarily large Reynolds numbers.
Turbulent flow velocity distribution at rough walls
International Nuclear Information System (INIS)
Baumann, W.
1978-08-01
Following extensive measurements of the velocity profile in a plate channel with artificial roughness geometries specific investigations were carried out to verify the results obtained. The wall geometry used was formed by high transverse square ribs having a large pitch. The measuring position relative to the ribs was varied as a parameter thus providing a statement on the local influence of roughness ribs on the values measured. As a fundamental result it was found that the gradient of the logarithmic rough wall velocity profiles, which differs widely from the value 2.5, depends but slightly on the measuring position relative to the ribs. The gradients of the smooth wall velocity profiles deviate from 2.5 near the ribs, only. This fact can be explained by the smooth wall shear stress varying with the pitch of the ribs. (orig.) 891 GL [de
Irregular wall roughness in turbulent Taylor-Couette flow
Berghout, Pieter; Zhu, Xiaojue; Verzicco, Roberto; Lohse, Detlef; Stevens, Richard
2017-11-01
Many wall bounded flows in nature, engineering and transport are affected by surface roughness. Often, this has adverse effects, e.g. drag increase leading to higher energy costs. A major difficulty is the infinite number of roughness geometries, which makes it impossible to systematically investigate all possibilities. Here we present Direct Numerical Simulations (DNS) of turbulent Taylor-Couette flow. We focus on the transitionally rough regime, in which both viscous and pressure forces contribute to the total wall stress. We investigate the effect of the mean roughness height and the effective slope on the roughness function, ΔU+ . Also, we present simulations of varying Ta (Re) numbers for a constant mean roughness height (kmean+). Alongside, we show the behavior of the large scale structures (e.g. plume ejection, Taylor rolls) and flow structures in the vicinity of the wall.
Numerical simulation of wall roughness effects in cavitating flow
International Nuclear Information System (INIS)
Echouchene, F.; Belmabrouk, H.; Le Penven, L.; Buffat, M.
2011-01-01
Hydrodynamic cavitation has an important effect on the performance of Diesel injectors. It influences the nature of the fuel spray and the efficiency of the combustion process. In the present study, we investigate numerically the effect of wall roughness in the cavitating and turbulent flow developing inside a Diesel injector. The mixture model based on a single fluid is adopted and the commercial Fluent software is used to solve the transport equations. The discharge coefficient C d is computed for different cavitation numbers and wall roughness heights. Profiles of density mixture, vapor volume fraction, mean velocity and turbulent kinetic energy are reported. The effects of wall roughness and injection pressure are analyzed.
Progress Towards an LES Wall Model Including Unresolved Roughness
Craft, Kyle; Redman, Andrew; Aikens, Kurt
2015-11-01
Wall models used in large eddy simulations (LES) are often based on theories for hydraulically smooth walls. While this is reasonable for many applications, there are also many where the impact of surface roughness is important. A previously developed wall model has been used primarily for jet engine aeroacoustics. However, jet simulations have not accurately captured thick initial shear layers found in some experimental data. This may partly be due to nozzle wall roughness used in the experiments to promote turbulent boundary layers. As a result, the wall model is extended to include the effects of unresolved wall roughness through appropriate alterations to the log-law. The methodology is tested for incompressible flat plate boundary layers with different surface roughness. Correct trends are noted for the impact of surface roughness on the velocity profile. However, velocity deficit profiles and the Reynolds stresses do not collapse as well as expected. Possible reasons for the discrepancies as well as future work will be presented. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1053575. Computational resources on TACC Stampede were provided under XSEDE allocation ENG150001.
Pathikonda, Gokul; Clark, Caitlyn; Christensen, Kenneth T.
2017-11-01
Inner-outer interactions over rough-wall boundary layer were investigated using high frame-rate, PIV measurements in a Refractive index-matched (RIM) facility. Flows over canonical smooth-wall and hexagonally-packed hemispherical roughness under transitionally rough flow conditions (and with Reτ 1500) were measured using a dual camera PIV system with different fields of view (FOVs) and operating simultaneously. The large FOV measures the large scales and boundary layer parameters, while the small FOV measures the small scales very close to the wall with high spatial ( 7y*) and temporal ( 2.5t*) resolutions. Conditional metrics were formulated to investigate these scale interactions in a spatio-temporal sense using the PIV data. It was found that the observations complement the interaction structure made via hotwire experiments and DNS in previous studies over both smooth and rough-wall flows, with a strong correlation between the large scales and small scale energies indicative of the amplitude modulation interactions. Additionally, frequency and scale modulations were also investigated with limited success. These experiments highlight the similarities and differences in these interactions between the smooth- and rough-wall flows.
Numerical simulation of wall roughness effects in cavitating flow
Energy Technology Data Exchange (ETDEWEB)
Echouchene, F. [Laboratoire d' electronique et de microelectronique, Departement de Physique, Faculte des Sciences de Monastir, 5000 (Tunisia); Belmabrouk, H., E-mail: frchouchene@yahoo.fr [Laboratoire d' electronique et de microelectronique, Departement de Physique, Faculte des Sciences de Monastir, 5000 (Tunisia); Le Penven, L.; Buffat, M. [LMFA UMR CNRS 5509, Universite de Claude Bernard Lyon 1, Ecole Centrale de Lyon, INSA de Lyon (France)
2011-10-15
Hydrodynamic cavitation has an important effect on the performance of Diesel injectors. It influences the nature of the fuel spray and the efficiency of the combustion process. In the present study, we investigate numerically the effect of wall roughness in the cavitating and turbulent flow developing inside a Diesel injector. The mixture model based on a single fluid is adopted and the commercial Fluent software is used to solve the transport equations. The discharge coefficient C{sub d} is computed for different cavitation numbers and wall roughness heights. Profiles of density mixture, vapor volume fraction, mean velocity and turbulent kinetic energy are reported. The effects of wall roughness and injection pressure are analyzed.
Velocity distribution in a turbulent flow near a rough wall
Korsun, A. S.; Pisarevsky, M. I.; Fedoseev, V. N.; Kreps, M. V.
2017-11-01
Velocity distribution in the zone of developed wall turbulence, regardless of the conditions on the wall, is described by the well-known Prandtl logarithmic profile. In this distribution, the constant, that determines the value of the velocity, is determined by the nature of the interaction of the flow with the wall and depends on the viscosity of the fluid, the dynamic velocity, and the parameters of the wall roughness.In extreme cases depending on the ratio between the thickness of the viscous sublayer and the size of the roughness the constant takes on a value that does not depend on viscosity, or leads to a ratio for a smooth wall.It is essential that this logarithmic profile is the result not only of the Prandtl theory, but can be derived from general considerations of the theory of dimensions, and also follows from the condition of local equilibrium of generation and dissipation of turbulent energy in the wall area. This allows us to consider the profile as a universal law of velocity distribution in the wall area of a turbulent flow.The profile approximation up to the maximum speed line with subsequent integration makes possible to obtain the resistance law for channels of simple shape. For channels of complex shape with rough walls, the universal profile can be used to formulate the boundary condition when applied to the calculation of turbulence models.This paper presents an empirical model for determining the constant of the universal logarithmic profile. The zone of roughness is described by a set of parameters and is considered as a porous structure with variable porosity.
Bai, H. L.; Kevin, Hutchins, N.; Monty, J. P.
2018-05-01
Turbulence modifications over a rough wall with spanwise-varying roughness are investigated at a moderate Reynolds number Reτ ≈ 2000 (or Reθ ≈ 6400), using particle image velocimetry (PIV) and hotwire anemometry. The rough wall is comprised of spanwise-alternating longitudinal sandpaper strips of two different roughness heights. The ratio of high- and low-roughness heights is 8, and the ratio of high- and low-roughness strip width is 0.5. PIV measurements are conducted in a wall-parallel plane located in the logarithmic region, while hotwire measurements are made throughout the entire boundary layer in a cross-stream plane. In a time-average sense, large-scale counter-rotating roll-modes are observed in the cross-stream plane over the rough wall, with downwash and upwash common-flows displayed over the high- and low-roughness strips, respectively. Meanwhile, elevated and reduced streamwise velocities occur over the high- and low-roughness strips, respectively. Significant modifications in the distributions of mean vorticities and Reynolds stresses are observed, exhibiting features of spatial preference. Furthermore, spatial correlations and conditional average analyses are performed to examine the alterations of turbulence structures over the rough wall, revealing that the time-invariant structures observed are resultant from the time-average process of instantaneous turbulent events that occur mostly and preferentially in space.
Rough-wall turbulent boundary layers with constant skin friction
Sridhar, A.
2017-03-28
A semi-empirical model is presented that describes the development of a fully developed turbulent boundary layer in the presence of surface roughness with length scale ks that varies with streamwise distance x . Interest is centred on flows for which all terms of the von Kármán integral relation, including the ratio of outer velocity to friction velocity U+∞≡U∞/uτ , are streamwise constant. For Rex assumed large, use is made of a simple log-wake model of the local turbulent mean-velocity profile that contains a standard mean-velocity correction for the asymptotic fully rough regime and with assumed constant parameter values. It is then shown that, for a general power-law external velocity variation U∞∼xm , all measures of the boundary-layer thickness must be proportional to x and that the surface sand-grain roughness scale variation must be the linear form ks(x)=αx , where x is the distance from the boundary layer of zero thickness and α is a dimensionless constant. This is shown to give a two-parameter (m,α) family of solutions, for which U+∞ (or equivalently Cf ) and boundary-layer thicknesses can be simply calculated. These correspond to perfectly self-similar boundary-layer growth in the streamwise direction with similarity variable z/(αx) , where z is the wall-normal coordinate. Results from this model over a range of α are discussed for several cases, including the zero-pressure-gradient ( m=0 ) and sink-flow ( m=−1 ) boundary layers. Trends observed in the model are supported by wall-modelled large-eddy simulation of the zero-pressure-gradient case for Rex in the range 108−1010 and for four values of α . Linear streamwise growth of the displacement, momentum and nominal boundary-layer thicknesses is confirmed, while, for each α , the mean-velocity profiles and streamwise turbulent variances are found to collapse reasonably well onto z/(αx) . For given α , calculations of U+∞ obtained from large-eddy simulations are streamwise
Near Wall measurement in Turbulent Flow over Rough Wall using microscopic HPIV
Talapatra, Siddharth; Hong, Jiarong; Katz, Joseph
2009-11-01
Using holographic PIV, 3D velocity measurements are being performed in a turbulent rough wall channel flow. Our objective is to examine the contribution of coherent structures to the flow dynamics, momentum and energy fluxes in the roughness sublayer. The 0.45mm high, pyramid-shaped roughness is uniformly distributed on the top and bottom surfaces of a 5X20cm rectangular channel flow, where the Reτ is 3400. To facilitate recording of holograms through a rough plate, the working fluid is a concentrated solution of NaI in water, whose optical refractive index is matched with that of the acrylic rough plates. The test section is illuminated by a collimated laser beam from the top, and the sample volume extends from the bottom wall up to 7 roughness heights. After passing through the sample volume, the in-line hologram is magnified and recorded on a 4864X3248 pixels camera at a resolution of 0.74μm/pixel. The flow is locally seeded with 2μm particles. Reconstruction, spatial filtering and particle tracking provide the 3D velocity field. This approach has been successfully implemented recently, as preliminary data demonstrate.
An analytical wall-function for turbulent flows and heat transfer over rough walls
International Nuclear Information System (INIS)
Suga, K.; Craft, T.J.; Iacovides, H.
2006-01-01
This paper reports the development of a refined wall-function strategy for the modelling of turbulent forced convection heat transfer over smooth and rough surfaces. In order to include the effects of fine-grain surface roughness, the present study extends a more fundamental work by Craft et al. [Craft, T.J., Gerasimov, A.V., Iacovides, H., Launder, B.E., 2002. Progress in the generalisation of wall-function treatment. Int. J. Heat Fluid Flow 23, 148-160] on the development of advanced wall-functions of general applicability. The presently proposed model is validated through comparisons with data available for internal flows through channels and for external flows over flat and curved plates with both smooth and rough surfaces. Then, its further validation in separating flows over a sand dune and a sand-roughened ramp is discussed. The validation results suggest that the presently proposed form can be successfully applied to a wide range of attached and separated turbulent flows with heat transfer over smooth and fine-grain rough surfaces
American Society for Testing and Materials. Philadelphia
2007-01-01
1.1 A qualitative estimate of the residual circumferential stress in thin-walled tubing may be calculated from the change in outside diameter that occurs upon splitting a length of the tubing. This practice assumes a linear stress distribution through the tube wall thickness and will not provide an estimate of local stress distributions such as surface stresses. (Very high local residual stress gradients are common at the surface of metal tubing due to cold drawing, peening, grinding, etc.) The Hatfield and Thirkell formula, as later modified by Sachs and Espey, provides a simple method for calculating the approximate circumferential stress from the change in diameter of straight, thin-walled, metal tubing. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Active Brownian particles near straight or curved walls: Pressure and boundary layers
Duzgun, Ayhan; Selinger, Jonathan V.
2018-03-01
Unlike equilibrium systems, active matter is not governed by the conventional laws of thermodynamics. Through a series of analytic calculations and Langevin dynamics simulations, we explore how systems cross over from equilibrium to active behavior as the activity is increased. In particular, we calculate the profiles of density and orientational order near straight or circular walls and show the characteristic width of the boundary layers. We find a simple relationship between the enhancements of density and pressure near a wall. Based on these results, we determine how the pressure depends on wall curvature and hence make approximate analytic predictions for the motion of curved tracers, as well as the rectification of active particles around small openings in confined geometries.
Turbulence Intensity and the Friction Factor for Smooth- and Rough-Wall Pipe Flow
Nils T. Basse
2017-01-01
Turbulence intensity profiles are compared for smooth- and rough-wall pipe flow measurements made in the Princeton Superpipe. The profile development in the transition from hydraulically smooth to fully rough flow displays a propagating sequence from the pipe wall towards the pipe axis. The scaling of turbulence intensity with Reynolds number shows that the smooth- and rough wall level deviates with increasing Reynolds number. We quantify the correspondence between turbulence intensity and th...
Rough-wall turbulent boundary layers with constant skin friction
Sridhar, A.; Pullin, D. I.; Cheng, W.
2017-01-01
A semi-empirical model is presented that describes the development of a fully developed turbulent boundary layer in the presence of surface roughness with length scale ks that varies with streamwise distance x . Interest is centred on flows
Effects of wall roughness and entry length on void profile in vertical bubbly flow
International Nuclear Information System (INIS)
Takamasa, Tomoji
1988-01-01
An experimental study of upward air-water bubbly two-phase flow in an entry region was performed with various rough wall test tubes. The objective of the work is to clarify the effects of wall roughness and entry length on void profile. The fluid flows in the vertical circular test tube of 25 mm I.D. under nearly atmospheric pressure, at room temperature. The void profile changes from a pattern similar in appearance to the saddle shape which has local void peaks near the wall, into the power law shape whose curve is approximated by a power law formula, with increasing wall roughness and/or entry length. That is, wall roughness and entry length have a similar effect upon void profile. There are two patterns in the power law shape, a pattern with sharp center peak and a pattern with obtuse center peak. As wall roughness and/or entry length increase, the void profile changes from the former pattern to the latter pattern. At enough long entry length (L/D ≅ 150), every void profile has almost the same power law shape independent of wall roughness. Some void profiles are asymmetric to the axis. (author)
Modeling of Two-Phase Flow in Rough-Walled Fracture Using Level Set Method
Directory of Open Access Journals (Sweden)
Yunfeng Dai
2017-01-01
Full Text Available To describe accurately the flow characteristic of fracture scale displacements of immiscible fluids, an incompressible two-phase (crude oil and water flow model incorporating interfacial forces and nonzero contact angles is developed. The roughness of the two-dimensional synthetic rough-walled fractures is controlled with different fractal dimension parameters. Described by the Navier–Stokes equations, the moving interface between crude oil and water is tracked using level set method. The method accounts for differences in densities and viscosities of crude oil and water and includes the effect of interfacial force. The wettability of the rough fracture wall is taken into account by defining the contact angle and slip length. The curve of the invasion pressure-water volume fraction is generated by modeling two-phase flow during a sudden drainage. The volume fraction of water restricted in the rough-walled fracture is calculated by integrating the water volume and dividing by the total cavity volume of the fracture while the two-phase flow is quasistatic. The effect of invasion pressure of crude oil, roughness of fracture wall, and wettability of the wall on two-phase flow in rough-walled fracture is evaluated.
Analysis of the coherent and turbulent stresses of a numerically simulated rough wall pipe
Chan, L.; MacDonald, M.; Chung, D.; Hutchins, N.; Ooi, A.
2017-04-01
A turbulent rough wall flow in a pipe is simulated using direct numerical simulation (DNS) where the roughness elements consist of explicitly gridded three-dimensional sinusoids. Two groups of simulations were conducted where the roughness semi-amplitude h+ and the roughness wavelength λ+ are systematically varied. The triple decomposition is applied to the velocity to separate the coherent and turbulent components. The coherent or dispersive component arises due to the roughness and depends on the topological features of the surface. The turbulent stress on the other hand, scales with the friction Reynolds number. For the case with the largest roughness wavelength, large secondary flows are observed which are similar to that of duct flows. The occurrence of these large secondary flows is due to the spanwise heterogeneity of the roughness which has a spacing approximately equal to the boundary layer thickness δ.
Roughness Effects on Organized Motions in a Wall Shear Layer Flow
Haigermoser, Christian; Vesely, Lukas; Lapolla, Massimillano; Onorato, Michele
2006-11-01
Turbulent boundary layer measurements on a zero-pressure gradient flat plate with two different roughness, a 2D and a 3D roughness, were carried out. The main object of the study was to investigate the impact of the wall roughness on the turbulent flow structures. The momentum thickness Reynolds number for the smooth wall was Reθ˜ 1900. PIV measurements were taken in the streamwise wall-normal plane. The PIV images covered the whole logarithmic region and the major part of the outer layer. The instant flow images for the two roughness show features similar to the one expected in a smooth wall turbulent boundary layer, as described by Adrian et al. (JFM 2000). Statistical analysis was performed to enlighten quantitative differences between the different flow fields. For instance, two point streamwise velocity correlations show that the major effect of the roughness is to tilt the inclination of the hairpin vortex packets towards the wall normal direction; being the 3D roughness more effective in producing this displacement. Full results will be shown and discussed during the presentation.
Smooth- and rough-wall boundary layer structure from high spatial range particle image velocimetry
Squire, D. T.; Morrill-Winter, C.; Hutchins, N.; Marusic, I.; Schultz, M. P.; Klewicki, J. C.
2016-10-01
Two particle image velocimetry arrangements are used to make true spatial comparisons between smooth- and rough-wall boundary layers at high Reynolds numbers across a very wide range of streamwise scales. Together, the arrangements resolve scales ranging from motions on the order of the Kolmogorov microscale to those longer than twice the boundary layer thickness. The rough-wall experiments were obtained above a continuous sandpaper sheet, identical to that used by Squire et al. [J. Fluid Mech. 795, 210 (2016), 10.1017/jfm.2016.196], and cover a range of friction and equivalent sand-grain roughness Reynolds numbers (12 000 ≲δ+≲ 18000, 62 ≲ks+≲104 ). The smooth-wall experiments comprise new and previously published data spanning 6500 ≲δ+≲17 000 . Flow statistics from all experiments show similar Reynolds number trends and behaviors to recent, well-resolved hot-wire anemometry measurements above the same rough surface. Comparisons, at matched δ+, between smooth- and rough-wall two-point correlation maps and two-point magnitude-squared coherence maps demonstrate that spatially the outer region of the boundary layer is the same between the two flows. This is apparently true even at wall-normal locations where the total (inner-normalized) energy differs between the smooth and rough wall. Generally, the present results provide strong support for Townsend's [The Structure of Turbulent Shear Flow (Cambridge University Press, Cambridge, 1956), Vol. 1] wall-similarity hypothesis in high Reynolds number fully rough boundary layer flows.
Wall roughness effects on flow and scouring in curved channels with gravel bed
Hersberger, Daniel S.
2002-01-01
Wall roughness effects on flow and scouring in curved channels with gravel bed In the narrow valleys in Alpine regions, rivers frequently flow across constructed zones, passing through villages and cities. Due to limited space, the protection from high floods often needs to be ensured by protection walls. During floods, these protection walls may be endangered by scour phenomena, especially if they are located in bends. In the past, the potential danger of underscoured structures was reduced ...
Hamedon, Zamzuri; Kuang, Shea Cheng; Jaafar, Hasnulhadi; Azhari, Azmir
2018-03-01
Incremental sheet forming is a versatile sheet metal forming process where a sheet metal is formed into its final shape by a series of localized deformation without a specialised die. However, it still has many shortcomings that need to be overcome such as geometric accuracy, surface roughness, formability, forming speed, and so on. This project focus on minimising the surface roughness of aluminium sheet and improving its thickness uniformity in incremental sheet forming via optimisation of wall angle, feed rate, and step size. Besides, the effect of wall angle, feed rate, and step size to the surface roughness and thickness uniformity of aluminium sheet was investigated in this project. From the results, it was observed that surface roughness and thickness uniformity were inversely varied due to the formation of surface waviness. Increase in feed rate and decrease in step size will produce a lower surface roughness, while uniform thickness reduction was obtained by reducing the wall angle and step size. By using Taguchi analysis, the optimum parameters for minimum surface roughness and uniform thickness reduction of aluminium sheet were determined. The finding of this project helps to reduce the time in optimising the surface roughness and thickness uniformity in incremental sheet forming.
The distribution of wall shear stress downstream of a change in roughness
International Nuclear Information System (INIS)
Loureiro, J.B.R.; Sousa, F.B.C.C.; Zotin, J.L.Z.; Silva Freire, A.P.
2010-01-01
In the present work, six different experimental techniques are used to characterize the non-equilibrium flow downstream of a rough-to-smooth step change in surface roughness. Over the rough surface, wall shear stress results obtained through the form drag and the Reynolds stress methods are shown to be mutually consistent. Over the smooth surface, reference wall shear stress data is obtained through two optical methods: linear velocity profiles obtained through laser-Doppler anemometry and a sensor surface, the diverging fringe Doppler sensor. The work shows that the two most commonly used methods to determine the wall shear stress, the log-law gradient method and the Reynolds shear stress method, are completely inappropriate in the developing flow region. Preston tubes, on the other hand, are shown to perform well in the region of a non-equilibrium flow.
Time Resolved Tomographic PIV Measurements of Rough-Wall Turbulent Channel Flow
Miorini, Rinaldo; Zhang, Cao; Katz, Joseph
2013-11-01
Time resolved tomographic PIV is used to study flow structures in the outer region of a rough-wall turbulent boundary layer, focusing on imprints of the roughness on the outer layer. Measurements are performed in a transparent channel installed in the JHU optically index matched facility. The roughness consists of pyramids with height, k = 0.46 mm, and wavelength, λ = 3.2 mm, satisfying h/k = 55 (h = 25.4 mm is the channel half-height), k + = 64 and Re = 40000. The TPIV setup consists of four high-speed cameras operating at 3 kHz, which view the sample volume through acrylic prisms. The flow field is illuminated by an Nd:YLF laser. Following enhancement, calibration, and reconstruction, 643 voxels interrogation volumes with 0.75 overlap provide 3D velocity fields with spacing of 0.5883 mm3. Formation and transport of near-wall 3D U-shaped vortex structures, with base in front of the pyramids, and quasi-streamwise legs extending between pyramid crest lines are evident from the data. Extended streamwise regions of high wall-normal vorticity appear ``latched'' to the roughness elements close to the wall, but are transported downstream at higher elevations. Also evident are traveling streamwise low velocity streaks, which cover many roughness elements. Sponsored by NSF CBET and ONR.
Capillary condensation in pores with rough walls: a density functional approach.
Bryk, P; Rzysko, W; Malijevsky, Al; Sokołowski, S
2007-09-01
The effect of surface roughness of slit-like pore walls on the capillary condensation of a spherical particles and short chains is studied. The gas molecules interact with the substrate by a Lennard-Jones (9,3) potential. The rough layer at each pore wall has a variable thickness and density and consists of a disordered quenched matrix of spherical particles. The system is described in the framework of a density functional approach and using computer simulations. The contribution due to attractive van der Waals interactions between adsorbate molecules is described by using first-order mean spherical approximation and mean-field approximation.
Diffusion of drag-reducing polymer solutions within a rough-walled turbulent boundary layer
Elbing, Brian R.; Dowling, David R.; Perlin, Marc; Ceccio, Steven L.
2010-04-01
The influence of surface roughness on diffusion of wall-injected, drag-reducing polymer solutions within a turbulent boundary layer was studied with a 0.94 m long flat-plate test model at speeds of up to 10.6 m s-1 and Reynolds numbers of up to 9×106. The surface was hydraulically smooth, transitionally rough, or fully rough. Mean concentration profiles were acquired with planar laser induced fluorescence, which was the primary flow diagnostic. Polymer concentration profiles with high injection concentrations (≥1000 wppm) had the peak concentration shifted away from the wall, which was partially attributed to a lifting phenomenon. The diffusion process was divided into three zones—initial, intermediate, and final. Studies of polymer injection into a polymer ocean at concentrations sufficient for maximum drag reduction indicated that the maximum initial zone length is of the order of 100 boundary layer thicknesses. The intermediate zone results indicate that friction velocity and roughness height are important scaling parameters in addition to flow and injection conditions. Lastly, the current results were combined with those in Petrie et al. ["Polymer drag reduction with surface roughness in flat-plate turbulent boundary layer flow," Exp. Fluids 35, 8 (2003)] to demonstrate that the influence of polymer degradation increases with increased surface roughness.
Disentangling the origins of torque enhancement through wall roughness in Taylor-Couette turbulence
Zhu, Xiaojue; Verzicco, Roberto; Lohse, Detlef
2017-01-01
Direct numerical simulations (DNS) are performed to analyse the global transport properties of turbulent Taylor-Couette flow with inner rough wall up to Taylor number Ta = 1010. The dimensionless torque Nuω shows an effective scaling of Nuω ∝ Ta0.42±0.01, which is steeper than the ultimate regime
Rough wall skin friction measurements using a high resolution surface balance
International Nuclear Information System (INIS)
Krogstad, Per-Age; Efros, Vladislav
2010-01-01
This paper describes the design of a floating element friction balance which is based upon a commercially available micro force balance. The balance has a perfectly linear calibration function and was successfully applied to rough wall flows in a channel and a diffusor. Extrapolation of the turbulent shear stress measured by two component LDA to the wall matched very well the shear stress measured using the friction balance. Also, the wall shear stress obtained from the balance in the fully developed channel flow agreed with the stress that could be derived from the pressure gradient to within 3%.
Berim, Gersh O; Ruckenstein, Eli
2012-08-07
Adsorption isoterms and capillary condensation in an open slit with walls decorated with arrays of pillars are examined using the density functional theory. Compared with the main substrate, the pillars can have the same or different parameters in the Lennard-Jones interaction potential between them and the fluid in the slit. The roughness of the solid surface, defined as the ratio between the area of the actual surface and the area of the surface free of pillars, is controlled by the height of the pillars. It is shown that the capillary condensation pressure first increases with increasing roughness, passes through a maximum, and then decreases. The amount of adsorbed fluid at constant volume of the slit has, in general, a nonmonotonic dependence on roughness. These features of adsorption and capillary condensation are results of increased surface area and changes in the fluid-solid potential energy due to changes in roughness.
A methodology for including wall roughness effects in k-ε low-Reynolds turbulence models
International Nuclear Information System (INIS)
Ambrosini, W.; Pucciarelli, A.; Borroni, I.
2015-01-01
Highlights: • A model for taking into account wall roughness in low-Reynolds k-ε models is presented. • The model is subjected to a first validation to show its potential in general applications. • The application of the model in predicting heat transfer to supercritical fluids is also discussed. - Abstract: A model accounting for wall roughness effects in k-ε low-Reynolds turbulence models is described in the present paper. In particular, the introduction in the transport equations of k and ε of additional source terms related to roughness, based on simple assumptions and dimensional relationships, is proposed. An objective of the present paper, in addition to obtaining more realistic predictions of wall friction, is the application of the proposed model to the study of heat transfer to supercritical fluids. A first validation of the model is reported. The model shows the capability of predicting, at least qualitatively, some of the most important trends observed when dealing with rough pipes in very different flow conditions. Qualitative comparisons with some DNS data available in literature are also performed. Further analyses provided promising results concerning the ability of the model in reproducing the trend of friction factor when varying the flow conditions, though improvements are necessary for achieving better quantitative accuracy. First applications of the model in simulating heat transfer to supercritical fluids are also described, showing the capability of the model to affect the predictions of these heat transfer phenomena, in particular in the vicinity of the pseudo-critical conditions. A more extended application of the model to relevant deteriorated heat transfer conditions will clarify the usefulness of this modelling methodology in improving predictions of these difficult phenomena. Whatever the possible success in this particular application that motivated its development, this approach suggests a general methodology for accounting
A novel approach for quantifying the zero-plane displacement of rough-wall boundary layers
Ferreira, Manuel; Rodriguez-Lopez, Eduardo; Ganapathisubramani, Bharath; Aerodynamics; Flight Mechanics Team
2017-11-01
Indirect methods of wall shear stress (WSS) estimation are frequently used to characterise rough wall boundary-layer flows. The zero-plane displacement, hypothesised to be the vertical location where it acts, is often treated as a fitting parameter. However, it would be preferrable to measure both these quantities directly, especially for surfaces with large roughness elements where established scaling and similarity laws may not hold. In this talk we present a novel floating element balance that is able to measure not only the WSS but also the wall normal location at which it acts. While allowing compensation for mild static pressure gradients by means of a first-order analytical model. Its architecture is based on a parallel-shift linkage and it's fitted with custom built force transducers and a data acquisition system especially designed to achieve high Signal-to-Noise Ratios (SNR). The smooth-wall boundary-layer flow is used as benchmark to assess the accuracy of this balance. The values of skin friction coefficient show an agreement with hot-wire anemometry to within 2 % at a local Reynolds number Reθ = 4 ×103 up to 104. A rough surface of regularly distributed large elements is used to investigate the ability to infer the zero-plane displacement.
Directory of Open Access Journals (Sweden)
Ahmed Rechia
2007-09-01
Full Text Available The aim of this work is to predict numerically the turbulent flow through a straight square duct using Reynolds Average Navier-Stokes equations (RANS by the widely used k – ε and a near wall turbulence k – ε − fμ models. To handle wall proximity and no-equilibrium effects, the first model is modified by incorporating damping functions fμ via the eddy viscosity relation. The predicted results for the streamwise, spanwise velocities and the Reynolds stress components are compared to those given by the k – ε model and by the direct numerical simulation (DNS data of Gavrilakis (J. Fluid Mech., 1992. In light of these results, the proposed k – ε − fμ model is found to be generally satisfactory for predicting the considered flow.
International Nuclear Information System (INIS)
Martinez, Eduardo
2012-01-01
The domain wall dynamics along thin ferromagnetic strips with high perpendicular magnetocrystalline anisotropy driven by either magnetic fields or spin-polarized currents is theoretically analyzed by means of full micromagnetic simulations and a one-dimensional model, including both surface roughness and thermal effects. At finite temperature, the results show a field dependence of the domain wall velocity in good qualitative agreement with available experimental measurements, indicating a low field, low velocity creep regime, and a high field, linear regime separated by a smeared depinning region. Similar behaviors were also observed under applied currents. In the low current creep regime the velocity-current characteristic does not depend significantly on the non-adiabaticity. At high currents, where the domain wall velocity becomes insensitive to surface pinning, the domain wall shows a precessional behavior even when the non-adiabatic parameter is equal to the Gilbert damping. These analyses confirm the relevance of both thermal fluctuations and surface roughness for the domain wall dynamics, and that complete micromagnetic modeling and one-dimensional studies taking into account these effects are required to interpret the experimental measurements in order to get a better understanding of the origin, the role and the magnitude of the non-adiabaticity. (paper)
High Reynolds number rough wall turbulent boundary layer experiments using Braille surfaces
Harris, Michael; Monty, Jason; Nova, Todd; Allen, James; Chong, Min
2007-11-01
This paper details smooth, transitional and fully rough turbulent boundary layer experiments in the New Mexico State high Reynolds number rough wall wind tunnel. The initial surface tested was generated with a Braille printer and consisted of an uniform array of Braille points. The average point height being 0.5mm, the spacing between the points in the span was 0.5mm and the surface consisted of span wise rows separated by 4mm. The wavelength to peak ratio was 8:1. The boundary layer thickness at the measurement location was 190mm giving a large separation of roughness height to layer thickness. The maximum friction velocity was uτ=1.5m/s at Rex=3.8 x10^7. Results for the skin friction co-efficient show that this surface follows a Nikuradse type inflectional curve and that Townsends outer layer similarity hypothesis is valid for rough wall flows with a large separation of scales. Mean flow and turbulence statistics will be presented.
Lee, S.; Yeo, I.; Lee, K.
2012-12-01
Understanding detailed solute transport mechanism in a single fracture is required to expand it to the complex fractured medium. Dispersion in the variable-aperture fractures occurs by combined effects of molecular diffusion, macro dispersion and Taylor dispersion. It has been reported that Taylor dispersion which is proportional to the square of the velocity dominates for the high velocity, while macro dispersion is proportional to the velocity. Contributions of each scheme are different as the velocity changes. To investigate relationship between Reynolds number and dispersion coefficient, single acrylic rough-walled fracture which has 20 cm length and 1.03 mm average aperture was designed. In this experiment, dispersion coefficient was calculated at the middle of the fracture and at the edge of the fracture via moment analysis using breakthrough curve (BTC) of fluorescent solute under the Reynolds number 0.08, 0.28, 2.78, 8.2 and 16.4. In the results, distinct dispersion regime was observed at the highly rough-walled fracture, which is inconsistent with the model that was suggested by previous research. In the range of Re 2.78. The reason of this transition zone was related to the generation of circulated flow near the wall. It can flush the trapped contaminant out to the main flow channel, which makes tailing effect diminished. Also, these circulation zones were visualized using microscope, CCD camera and fluorescent particles.
Experimental study of a turbulent boundary layer on a rough wall
International Nuclear Information System (INIS)
Trijoulet, Alexandre
1999-01-01
This research thesis reports the definition and results of an experimental study of a two-dimensional incompressible turbulent boundary layer on a rough wall in presence of pressure gradients. This study is motivated by problems met on pump blades by EDF. The author first reports a detailed bibliographical study on the current knowledge regarding the structure of turbulent boundary layers on smooth and rough walls, while more particularly focusing on the notion of wall law. Based on an analysis of Navier-Stokes equations, the author discusses the elaboration of a local partial similitude between two-dimensional flows obtained in wind tunnel and three-dimensional flows in presence of a uniform rotation for flows present within pumps. Thus, the author reproduces the main characteristics of boundary layers on pump walls in a simplified experimental arrangement in which detailed and reliable measurements are possible. In the next part, the author addresses the case of helical-centrifugal pumps. Based on calculation performed by other authors, the above-mentioned similitude parameters are assessed. Results are used to define experimental arrangements suitable for this study. An experimental installation is then presented, as well as the data processing scheme. Experimental results are presented and discussed for flows without pressure gradient, slowed down or accelerated on different surface conditions [fr
Hydraulic properties of 3D rough-walled fractures during shearing: An experimental study
Yin, Qian; Ma, Guowei; Jing, Hongwen; Wang, Huidong; Su, Haijian; Wang, Yingchao; Liu, Richeng
2017-12-01
This study experimentally analyzed the influence of shear processes on nonlinear flow behavior through 3D rough-walled rock fractures. A high-precision apparatus was developed to perform stress-dependent fluid flow tests of fractured rocks. Then, water flow tests on rough-walled fractures with different mechanical displacements were conducted. At each shear level, the hydraulic pressure ranged from 0 to 0.6 MPa, and the normal load varied from 7 to 35 kN. The results show that (i) the relationship between the volumetric flow rate and hydraulic gradient of rough-walled fractures can be well fit using Forchheimer's law. Notably, both the linear and nonlinear coefficients in Forchheimer's law decrease during shearing; (ii) a sixth-order polynomial function is used to evaluate the transmissivity based on the Reynolds number of fractures during shearing. The transmissivity exhibits a decreasing trend as the Reynolds number increases and an increasing trend as the shear displacement increases; (iii) the critical hydraulic gradient, critical Reynolds number and equivalent hydraulic aperture of the rock fractures all increase as the shear displacement increases. When the shear displacement varies from 0 to 15 mm, the critical hydraulic gradient ranges from 0.3 to 2.2 for a normal load of 7 kN and increases to 1.8-8.6 for a normal load of 35 kN; and (iv) the Forchheimer law results are evaluated by plotting the normalized transmissivity of the fractures during shearing against the Reynolds number. An increase in the normal load shifts the fitted curves downward. Additionally, the Forchheimer coefficient β decreases with the shear displacement but increases with the applied normal load.
Czech Academy of Sciences Publication Activity Database
Bucur, D.; Feireisl, Eduard; Nečasová, Šárka
2010-01-01
Roč. 197, č. 1 (2010), s. 117-138 ISSN 0003-9527 R&D Projects: GA MŠk LC06052; GA ČR GA201/08/0315; GA AV ČR IAA100190804 Institutional research plan: CEZ:AV0Z10190503 Keywords : Navier-Stokes system * wall roughness * Navier's slip Subject RIV: BA - General Mathematics Impact factor: 2.277, year: 2010 http://link.springer.com/article/10.1007%2Fs00205-009-0268-z
Euler–Lagrange simulation of gas–solid pipe flow with smooth and rough wall boundary conditions
DEFF Research Database (Denmark)
Mandø, Matthias; Yin, Chungen
2012-01-01
Numerical simulation of upward turbulent particle-laden pipe flow is performed with the intention to reveal the influence of surface roughness on the velocity statistics of the particle phase. A rough wall collision model, which models the surface as being sinusoidal, is proposed to account...... for the wall boundary condition ranging for smooth surfaces to very rough surfaces. This model accounts for the entire range of possible surface roughness found in pipes and industrial pneumatic equipment from smooth plastic pipes over machined steel pipes to cast iron surfaces. The model is based...... on a geometric interpretation of the wall collision process where the particle restitution coefficient is based on the data presented by Sommerfeld and Huber [1]. Simulations are performed using the Eulerian–Lagrangian methodology for the dilute one-way coupling regime. Results are reported for 3 different sizes...
International Nuclear Information System (INIS)
Pooja,; Ahluwalia, P. K.; Pathania, Y.
2015-01-01
This paper presents the results from a molecular dynamics simulation of mixture of argon and krypton in the Poiseuille flow across a rough walled nanochannel. The roughness effect on liquid nanoflows has recently drawn attention The computational software used for carrying out the molecular dynamics simulations is LAMMPS. The fluid flow takes place between two parallel plates and is bounded by horizontal rough walls in one direction and periodic boundary conditions are imposed in the other two directions. Each fluid atom interacts with other fluid atoms and wall atoms through Leenard-Jones (LJ) potential with a cut off distance of 5.0. To derive the flow a constant force is applied whose value is varied from 0.1 to 0.3 and velocity profiles and temperature profiles are noted for these values of forces. The velocity profile and temperature profiles are also looked at different channel widths of nanochannel and at different densities of mixture. The velocity profile and temperature profile of rough walled nanochannel are compared with that of smooth walled nanochannel and it is concluded that mean velocity increases with increase in channel width, force applied and decrease in density also with introduction of roughness in the walls of nanochannel mean velocity again increases and results also agree with the analytical solution of a Poiseuille flow
Failure pressure of straight pipe with wall thinning under internal pressure
International Nuclear Information System (INIS)
Kamaya, Masayuki; Suzuki, Tomohisa; Meshii, Toshiyuki
2008-01-01
The failure pressure of pipe with wall thinning was investigated by using three-dimensional elastic-plastic finite element analyses (FEA). With careful modeling of the pipe and flaw geometry in addition to a proper stress-strain relation of the material, FEA could estimate the precise burst pressure obtained by the tests. FEA was conducted by assuming three kinds of materials: line pipe steel, carbon steel, and stainless steel. The failure pressure obtained using line pipe steel was the lowest under the same flaw size condition, when the failure pressure was normalized by the value of unflawed pipe defined using the flow stress. On the other hand, when the failure pressure was normalized by the results of FEA obtained for unflawed pipe under various flaw and pipe configurations, the failure pressures of carbon steel and line pipe steel were almost the same and lower than that of stainless steel. This suggests that the existing assessment criteria developed for line pipe steel can be applied to make a conservative assessment of carbon steel and stainless steel
Elbing, Brian; Perlin, Marc; Dowling, David; Solomon, Michael; Ceccio, Steven
2008-11-01
Two experiments were conducted to investigate polymer drag reduction (PDR) within high Reynolds number (to 200 million based on downstream distance), rough-wall turbulent boundary layers. The first experiment was conducted at the U.S. Navy's Large Cavitation Channel on a 12.9 m long flat-plate at speeds to 20 m/s with the surface hydraulically smooth and fully rough. Local skin-friction measurements on the smooth and rough surfaces had maximum PDR levels of 65 and 75 percent, respectively. However, PDR decreased with increasing downstream distance and flow speed more rapidly on the rough surface, and at the top speed no measureable level of PDR was observed. The roughness-induced increased diffusion was quantified with near-wall concentration measurements and the second experiment, which measured concentration profiles on a 0.94 m long flat-plate with three surface conditions: smooth, 240-grit, and 60-grit sandpaper. The increased diffusion does not fully explain the smooth-rough PDR differences observed in the first experiment. Rheological analysis of drawn samples from the first experiment indicates that polymer degradation (chain scission) could be responsible for the remaining loss of rough-wall PDR. These results have implications for the cost effectiveness of PDR for surface ships.
International Nuclear Information System (INIS)
Liu, Wei; Tamai, Hidesada; Yoshida, Hiroyuki; Takase, Kazuyuki; Hayafune, Hiroki; Futagami, Satoshi; Kisohara, Naoyuki
2008-01-01
For the Steam Generator (SG) with straight double-walled heat transfer tube that used in sodium cooled Faster Breeder Reactor, flow instability is one of the most important items need researching. As the first step of the research, thermal hydraulics experiments were performed under high pressure condition in JAEA with using a straight tube. Pressure drop, heat transfer coefficients and void fraction data were derived. This paper evaluates the pressure drop data with TRAC-BF1 code. The Pffan's correlation for single phase flow and the Martinelli-Nelson's two-phase flow multiplier are found can be well predicted the present pressure drop data under high pressure condition. (author)
International Nuclear Information System (INIS)
Rodenburg, C.; Viswanathan, P.; Jepson, M.A.E.; Liu, X.; Battaglia, G.
2014-01-01
Due to their wide range of applications, porous polymers obtained from high internal phase emulsions have been widely studied using scanning electron microscopy. However, due to their lack of electrical conductivity, quantitative information of wall thicknesses and surface roughness, which are of particular interest to tissue engineering, has not been obtained. Here, Helium Ion Microscopy is used to examine uncoated polymer foams and some very strong but unexpected contrast is observed, the origin of which is established here. Based on this analysis, a method for the measurement of wall thickness variations and wall roughness measurements has been developed, based on the modeling of Helium ion transmission. The results presented here indicate that within the walls of the void structure there exist small features with height variations of ∼30 nm and wall thickness variations from ∼100 nm to larger 340 nm in regions surrounding interconnecting windows within the structure. The suggested imaging method is applicable to other porous carbon based structures with wall thicknesses in the range of 40–340 nm. - Highlights: • The first helium ion microscopy image of uncoated structures formed from HIPEs is presented. • Unusually high contrast features that change with accelerating voltage are observed. • The origin of the observed contrast is determined to be mass thickness contrast. • A new method for quantitative wall thickness variation/roughness measurements is demonstrated
Energy Technology Data Exchange (ETDEWEB)
Rodenburg, C., E-mail: c.rodenburg@sheffield.ac.uk [Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Viswanathan, P. [Department of Biomedical Sciences, University of Sheffield, Firth Court, Western Bank Sheffield, Sheffield S10 2 TN (United Kingdom); Jepson, M.A.E. [Department of Materials, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom); Liu, X. [Carl Zeiss Microscopy GmbH, Carl-Zeiss-Strasse 22, 73447 Oberkochen (Germany); Battaglia, G. [Department of Chemistry University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); The MRC/UCL Centre for Medical Molecular Virology, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)
2014-04-01
Due to their wide range of applications, porous polymers obtained from high internal phase emulsions have been widely studied using scanning electron microscopy. However, due to their lack of electrical conductivity, quantitative information of wall thicknesses and surface roughness, which are of particular interest to tissue engineering, has not been obtained. Here, Helium Ion Microscopy is used to examine uncoated polymer foams and some very strong but unexpected contrast is observed, the origin of which is established here. Based on this analysis, a method for the measurement of wall thickness variations and wall roughness measurements has been developed, based on the modeling of Helium ion transmission. The results presented here indicate that within the walls of the void structure there exist small features with height variations of ∼30 nm and wall thickness variations from ∼100 nm to larger 340 nm in regions surrounding interconnecting windows within the structure. The suggested imaging method is applicable to other porous carbon based structures with wall thicknesses in the range of 40–340 nm. - Highlights: • The first helium ion microscopy image of uncoated structures formed from HIPEs is presented. • Unusually high contrast features that change with accelerating voltage are observed. • The origin of the observed contrast is determined to be mass thickness contrast. • A new method for quantitative wall thickness variation/roughness measurements is demonstrated.
Hausnerova, Berenika; Sanetrnik, Daniel; Paravanova, Gordana
2014-05-01
The paper deals with the rheological behavior of highly filled compounds proceeded via powder injection molding (PIM) and applied in many sectors of industry (automotive, medicine, electronic or military). Online rheometer equipped with slit dies varying in surface roughness and dimensions was applied to investigate the wall-slip as a rheological phenomenon, which can be considered as a parameter indicating the separation of compound components (polymer binder and metallic powder) during high shear rates when injection molded.
International Nuclear Information System (INIS)
Moulton, Kellen; Jensen, Brian D; Morrill, Nicholas B; Konneker, Adam M; Vanfleet, Richard R; Allred, David D; Davis, Robert C
2012-01-01
This paper examines the effect of iron catalyst thickness on the straightness of growth of carbon nanotubes (CNTs) for microelectromechanical systems fabricated using the CNT-templated-microfabrication (CNT-M) process. SEM images of samples grown using various iron catalyst thicknesses show that both straight sidewalls and good edge definition are achieved using an iron thickness between 7 and 8 nm. Below this thickness, individual CNTs are well aligned, but the sidewalls of CNT forests formed into posts and long walls are not always straight. Above this thickness, the CNT forest sidewalls are relatively straight, but edge definition is poor, with significantly increased sidewall roughness. The proximity of a device or feature to other regions of iron catalyst also affects CNT growth. By using an iron catalyst thickness appropriate for straight growth, and by adding borders of iron around features or devices, a designer can greatly improve straightness of growth for CNT-MEMS. (paper)
Steyerl, A.; Malik, S. S.; Desai, A. M.; Kaufman, C.
2009-01-01
We review the diffuse scattering and the loss coefficient in ultracold neutron reflection from slightly rough surfaces, report a surprising reduction in loss coefficient due to roughness, and discuss the possibility of transition from quantum treatment to ray optics. The results are used in a computer simulation of neutron storage in a recent neutron lifetime experiment that re-ported a large discrepancy of neutron lifetime with the current particle data value. Our partial re-analysis suggest...
Non-Darcy Flow Experiments of Water Seepage through Rough-Walled Rock Fractures
Directory of Open Access Journals (Sweden)
Xiao-dong Ni
2018-01-01
Full Text Available The knowledge of flow phenomena in fractured rocks is very important for groundwater-resources management in hydrogeological engineering. The most commonly used tool to approximate the non-Darcy behavior of the flow velocity is the well-known Forchheimer equation, deploying the “inertial” coefficient β that can be estimated experimentally. Unfortunately, the factor of roughness is imperfectly considered in the literature. In order to do this, we designed and manufactured a seepage apparatus that can provide different roughness and aperture in the test; the rough fracture surface is established combining JRC and 3D printing technology. A series of hydraulic tests covering various flows were performed. Experimental data suggest that Forchheimer coefficients are to some extent affected by roughness and aperture. At last, favorable semiempirical Forchheimer equation which can consider fracture aperture and roughness was firstly derived. It is believed that such studies will be quite useful in identifying the limits of applicability of the well-known “cubic law,” in further improving theoretical/numerical models associated with fluid flow through a rough fracture.
International Nuclear Information System (INIS)
Yamaji, Akio; Saito, Tetsuo.
1988-01-01
To investigate a proximity effect of ducts on shield performance against γ radiation, an experiment was performed at JRR-4 by entering the γ-ray beam into a concrete shield wall of 100 cm-thickness with 3 or 5 straight cylindrical ducts of radius of 4.45 cm placed in a straight line or crosswise at interval of 8.9 cm. The dose rates were measured using digital dosimeters on a horizontal line 20 cm apart from the rear of the wall with 0, 1, 3 and 5 ducts, and with the incident angles of 0deg, 7deg, 14deg and 20deg, respectively. The dose rate distributions depended on the number of ducts and the incident angle, and the dose rate ratios of with-three-ducts to no-duct distributed within 3.6∼12, 1.3∼5.0 and 1.1∼4.3, for the incident angles of 7deg, 14deg and 20deg, while those of with-single-duct to no-duct within 1.2∼7.1, 1.1∼2.7 and 1.0∼1.9, respectively. The experiment was analyzed using a multigroup single scattering code G33YSN able to deal with the geometry of the ducts exactly. For each incident angle, the calculation agreed with the experiment within a factor of 2. (author)
International Nuclear Information System (INIS)
Chae, Byung Gon; Choi, Jung Hae; Ichikawa, Yasuaki; Seo, Yong Seok
2012-01-01
To compute a permeability coefficient along a rough fracture that takes into account the fracture geometry, this study performed detailed measurements of fracture roughness using a confocal laser scanning microscope, a quantitative analysis of roughness using a spectral analysis, and a homogenization analysis to calculate the permeability coefficient on the microand macro-scale. The homogenization analysis is a type of perturbation theory that characterizes the behavior of microscopically inhomogeneous material with a periodic boundary condition in the microstructure. Therefore, it is possible to analyze accurate permeability characteristics that are represented by the local effect of the fracture geometry. The Cpermeability coefficients that are calculated using the homogenization analysis for each rough fracture model exhibit an irregular distribution and do not follow the relationship of the cubic law. This distribution suggests that the permeability characteristics strongly depend on the geometric conditions of the fractures, such as the roughness and the aperture variation. The homogenization analysis may allow us to produce more accurate results than are possible with the preexisting equations for calculating permeability.
International Nuclear Information System (INIS)
Steyerl, A.; Malik, S. S.; Desai, A. M.; Kaufman, C.
2010-01-01
We review the diffuse scattering and the loss coefficient in ultracold neutron reflection from slightly rough surfaces, report a surprising reduction in loss coefficient due to roughness, and discuss the possibility of transition from quantum treatment to ray optics. The results are used in a computer simulation of neutron storage in a recent neutron lifetime experiment that reported a large discrepancy of neutron lifetime with the current particle data value. Our partial reanalysis suggests the possibility of systematic effects that were not included in this publication.
THE IMPACT OF WALL ROUGHNESS OF THE UNDERGROUND AIRWAYS ON THE VALUE OF HYDRAULIC FRICTION FACTOR
Directory of Open Access Journals (Sweden)
Vladimir Rendulić
1991-12-01
Full Text Available The studies of turbulent flows in round pipes resulted in many hydraulic formulas up to these days, which can also serve in projecting to calculate the resistance to the air flow in underground openings. The report discusses the way of establishing the hydraulic friction factor of untimbered underground workings when the value of equivalent roughness is obtained by measuring the ventilation parameters in a similar working of some other mine. A double reticular nomogram has been constructed for the fast determination of friction coefficient from the known roughness of an underground working (the paper is published in Croatian.
Directory of Open Access Journals (Sweden)
I E. Lobanov
2017-01-01
Full Text Available Objectives. The aim of present work was to carry out mathematical modelling of heat transfer with symmetrical heating in flat channels and round pipes with rough walls.Methods. The calculation was carried out using the L'Hôpital-Bernoulli's method. The solution of the problem of intensified heat transfer in a round tube with rough walls was obtained using the Lyon's integral.Results. Different from existing theories, a methodology of theoretical computational heat transfer determination for flat rough channels and round pipes with rough walls is developed on the basis of the principle of full viscosity superposition in a turbulent boundary layer. The analysis of the calculated heat transfer and hydroresistivity values for flat rough channels and round rough pipes shows that the increase in heat transfer is always less than the corresponding increase in hydraulic resistance, which is a disadvantage as compared to channels with turbulators, with all else being equal. The results of calculating the heat transfer for channels with rough walls in an extended range of determinant parameters, which differ significantly from the corresponding data for the channels with turbulators, determine the level of heat exchange intensification.Conclusion. An increase in the calculated values of the relative average heat transfer Nu/NuGL for flat rough channels and rough pipes with very high values of the relative roughness is significantly contributed by both an increase in the relative roughness height and an increase in the Reynolds number Re. In comparison with empirical dependencies, the main advantage of solutions for averaged heat transfer in rough flat channels and round pipes under symmetrical thermal load obtained according to the developed theory is that they allow the calculation of heat exchange in rough pipes to be made in the case of large and very large relative heights of roughness protrusions, including large Reynolds numbers, typical for pipes
International Nuclear Information System (INIS)
Herve, Patrick
1975-01-01
This is a theoretical study of an electrically viscous fluid flowing in a straight rectangular cross section channel, a wall of which, infinitely conducting, is placed perpendicularly to the direction of a uniform magnetic induction field. The three other walls of the channel being electrically insulating, remain motionless. Formulas giving velocity distribution law in the straight section of the flow in relation to the Hartmann's number, curves illustrating the accelerating effect produced across the whole section, by the application of the magnetic induction field, and example for the distribution of the electric current lines in case of a square section are given [fr
Lubrication theory analysis of the permeability of rough-walled fractures
International Nuclear Information System (INIS)
Zimmerman, R.W.; Kumar, S.; Bodvarsson, G.S.
1991-01-01
The flow of a fluid between the rough surfaces of a rock fracture is very complex, due to the tortuous paths followed by the fluid particles. Exact analytical modeling of these flows is made difficult by the irregular geometry of rock fracture surfaces, while full three-dimensional numerical simulations of these flows are as yet still impractical. To overcome the difficulties of working with the three-dimensional Navier-Stokes equations, the simpler Reynolds lubrication equation has sometimes been used to model flow in fractures. This paper focuses on two aspects of lubrication theory. First, lubrication theory is applied to two simplified aperture profiles, sinusoidal and sawtooth, and analytical expressions are found for the permeabilities. These results are then compared with numerical results obtained by solving the lubrication equation for fractures with random surfaces. Secondly, the validity of the lubrication equations for modeling flow in rough fractures is studied by examining higher-order perturbation solutions, as well as numerical solutions, to the Navier-Stokes equations for flow in fractures with sinusoidally-varying apertures. 22 refs., 6 figs
Wall-Roughness Effects on Flow and Scouring in Curved Channels with Gravel Beds
Hersberger, D.; Franca, Mário J.; Schleiss, Anton
2016-01-01
Due to a complex three-dimensional flow pattern, the outer banks of river bends are predisposed to erosion. When endangering civil structures, preventing measures to mitigate this erosion are thus required. Vertical ribs at protection walls for scour reduction have been applied to several flood protection projects in mountain rivers; nevertheless, no systematic and intensive study has been presented so far to evaluate their effect. This paper investigates experimentally the effect of vertical...
Meda, Adimurthy; Katti, Vadiraj V.
2017-08-01
The present work experimentally investigates the local distribution of wall static pressure and the heat transfer coefficient on a rough flat plate impinged by a slot air jet. The experimental parameters include, nozzle-to-plate spacing (Z /D h = 0.5-10.0), axial distance from stagnation point ( x/D h ), size of detached rib ( b = 4-12 mm) and Reynolds number ( Re = 2500-20,000). The wall static pressure on the surface is recorded using a Pitot tube and a differential pressure transmitter. Infrared thermal imaging technique is used to capture the temperature distribution on the target surface. It is observed that, the maximum wall static pressure occurs at the stagnation point ( x/D h = 0) for all nozzle-to-plate spacing ( Z/D h ) and rib dimensions studied. Coefficient of wall static pressure ( C p ) decreases monotonically with x/D h . Sub atmospheric pressure is evident in the detached rib configurations for jet to plate spacing up to 6.0 for all ribs studied. Sub atmospheric region is stronger at Z/D h = 0.5 due to the fluid accelerating under the rib. As nozzle to plate spacing ( Z/D h ) increases, the sub-atmospheric region becomes weak and vanishes gradually. Reasonable enhancement in both C p as well as Nu is observed for the detached rib configuration. Enhancement is found to decrease with the increase in the rib width. The results of the study can be used in optimizing the cooling system design.
Effects of flow depth and wall roughness on turbulence in compound channels
International Nuclear Information System (INIS)
Prinos, P.; Townsend, R.; Tavoularis, S.
1985-01-01
Current methods for estimating discharge in compound channels often lead to large errors. The error is largely due to momentum transfer mechanism (MTM) generated in the junction regions of the flow field (between adjacent deep and shallow zones). The MTM adversely affects system conveyance, particularly when the velocity differential between the deep and shallow zones is large. Improved prediction methods, therefore, will necessarily reflect the MTM's presence and its effect on the compound flow field. The mechanism's influence on system hydraulics is best examined by analysing the related turbulence characteristics in the junction zones of the compound section. Townsend reported increased turbulence levels in the junction region between a main channel and its shallower flood plain zone and Elsawy, McKee and McKeogh found that observed normal turbulent stresses in a similar region were of the same order of magnitude as the apparent shear stress on the junction's vertical interface plane. The objective of the present study is to measure turbulent stresses in the junction region of a symmetrical compound open channel and examine their dependence on relative depth and relative boundary roughness. Further details of this phase of the larger study are presented elsewhere. (author)
Energy Technology Data Exchange (ETDEWEB)
van den Heever, L W [Pretoria Univ. (South Africa). Div. Food Hygiene and Public Health
1977-01-01
Rough washed bovine ruminal wall is available at low cost in many African countries to traditional consumers of such offal. The consumers consistently oppose any further cleaning or processing which would alter its appearance or elevate its cost. Such offal undoubtedly possesses high nutritional value but is highly perishable product contaminated with numerous bacteria some of which are potential pathogens or toxigens. A preliminary investigation showed that the bacterial counts could be reduced by more that 90% by gamma radiation of such offal with doses of 100-200 krad. Such radiation doubled or trebled the keeping quality of the offal at 4/sup 0/C. Some of the organisms present in offal survive low doses of radiation. They were mainly species of the genera Bacillus, Micrococcus, Streptococcus, Staphylococcus and Clostridium, some of which survived 600 krad. Irradiation doses of 600 krad were in any event necessary to numerically reduce experimental contamination of minced ruminal wall with Staphylococcus aureus, Salmonella dublin and Clostridium perfringens to a level where these organisms could not be recovered by ordinary cultural procedures (the two strains of S. aureus tested varied in their radiation resistance).
International Nuclear Information System (INIS)
Heever, L.W. van den
1977-01-01
Rough washed bovine ruminal wall is available at low cost in many African countries to traditional consumers of such offal. The consumers consistently oppose any further cleaning or processing which would alter its appearance or elevate its cost. Such offal undoubtedly possesses high nutritional value but is highly perishable product contaminated with numerous bacteria some of which are potential pathogens or toxigens. A preliminary investigation showed that the bacterial counts could be reduced by more that 90% by gamma radiation of such offal with doses of 100-200 krad. Such radiation doubled or trebled the keeping quality of the offal at 4 0 C. Some of the organisms present in offal survive low doses of radiation. They were mainly species of the genera Bacillus, Micrococcus, Streptococcus, Staphylococcus and Clostridium, some of which survived 600 krad. Irradiation doses of 600 krad were in any event necessary to numerically reduce experimental contamination of minced ruminal wall with Staphylococcus aureus, Salmonella dublin and Clostridium perfringens to a level where these organisms could not be recovered by ordinary cultural procedures (the two strains of S. aureus tested varied in their radiation resistance). (orig.) [de
International Nuclear Information System (INIS)
Motozawa, Masaaki; Ito, Takahiro; Iwamoto, Kaoru; Kawashima, Hideki; Ando, Hirotomo; Senda, Tetsuya; Tsuji, Yoshiyuki; Kawaguchi, Yasuo
2013-01-01
Highlights: • Flow over the regularly distributed triangular ribs was investigated. • Simultaneous measurement of flow resistance and velocity profile was performed. • Flow resistance was measured directly and velocity profile was measured by LDV. • Flow resistance was estimated by the information of the velocity field. • Estimated flow resistance has good agreement with the measured flow resistance. -- Abstract: The relationship between the flow resistance of a turbulent flow over triangular ribs regularly distributed on a wall surface and the velocity distribution around the ribs was investigated experimentally. A concentric cylinder device composed of an inner test cylinder and an outer cylinder was employed to measure the flow resistance using the torque of the shaft of the inner cylinder and the velocity distribution of the flow around a rib by laser Doppler velocimetry (LDV) simultaneously. We prepared four inner test cylinders having 4, 8, 12 and 16 triangular ribs on the surface with the same interval between them. Each rib had an isosceles right triangle V-shape and a height of 2 mm. To investigate the relationship between flow resistance and velocity distribution, we estimated the frictional drag and pressure drag acting on the surface of the ribs separately using the velocity distribution. Therefore, we could also estimate the total flow resistance using the velocity distribution. As a result of the experiment, the flow resistance and the attachment point downstream of the rib were shown to depend on the distance between ribs. Moreover, the flow resistance estimated using the velocity distribution had good agreement with the flow resistance measured using the torque of the inner cylinder
Chu, Minghan; Meng, Fanxiao; Bergstrom, Donald J.
2017-11-01
An in-house computational fluid dynamics code was used to simulate turbulent flow over a flat plate with a step change in roughness, exhibiting a smooth-rough-smooth configuration. An internal boundary layer (IBL) is formed at the transition from the smooth to rough (SR) and then the rough to smooth (RS) surfaces. For an IBL the flow far above the surface has experienced a wall shear stress that is different from the local value. Within a Reynolds-Averaged-Navier-Stokes (RANS) formulation, the two-layer k- ɛ model of Durbin et al. (2001) was implemented to analyze the response of the flow to the change in surface condition. The numerical results are compared to experimental data, including some in-house measurements and the seminal work of Antonia and Luxton (1971,72). This problem captures some aspects of roughness in industrial and environmental applications, such as corrosion and the earth's surface heterogeneity, where the roughness is often encountered as discrete distributions. It illustrates the challenge of incorporating roughness models in RANS that are capable of responding to complex surface roughness profiles.
Kareem, Ali Khaleel; Gao, Shian
2018-02-01
The aim of the present numerical investigation is to comprehensively analyse and understand the heat transfer enhancement process using a roughened, heated bottom wall with two artificial rib types (R-s and R-c) due to unsteady mixed convection heat transfer in a 3D moving top wall enclosure that has a central rotating cylinder, and to compare these cases with the smooth bottom wall case. These different cases (roughened and smooth bottom walls) are considered at various clockwise and anticlockwise rotational speeds, -5 ≤ Ω ≤ 5, and Reynolds numbers of 5000 and 10 000. The top and bottom walls of the lid-driven cavity are differentially heated, whilst the remaining cavity walls are assumed to be stationary and adiabatic. A standard k-ɛ model for the Unsteady Reynolds-Averaged Navier-Stokes equations is used to deal with the turbulent flow. The heat transfer improvement is carefully considered and analysed through the detailed examinations of the flow and thermal fields, the turbulent kinetic energy, the mean velocity profiles, the wall shear stresses, and the local and average Nusselt numbers. It has been concluded that artificial roughness can strongly affect the thermal fields and fluid flow patterns. Ultimately, the heat transfer rate has been dramatically increased by involving the introduced artificial rips. Increasing the cylinder rotational speed or Reynolds number can enhance the heat transfer process, especially when the wall roughness exists.
Yang, Xiang; Sadique, Jasim; Mittal, Rajat; Meneveau, Charles
2014-11-01
A new wall model for Large-Eddy-Simulations is proposed. It is based on an integral boundary layer method that assumes a functional form for the local mean velocity profile. The method, iWMLES, evaluates required unsteady and advective terms in the vertically integrated boundary layer equations analytically. The assumed profile contains a viscous or roughness sublayer, and a logarithmic layer with an additional linear term accounting for inertial and pressure gradient effects. The iWMLES method is tested in the context of a finite difference LES code. Test cases include developing turbulent boundary layers on a smooth flat plate at various Reynolds numbers, over flat plates with unresolved roughness, and a sample application to boundary layer flow over a plate that includes resolved roughness elements. The elements are truncated cones acting as idealized barnacle-like roughness elements that often occur in biofouling of marine surfaces. Comparisons with data show that iWMLES provides accurate predictions of near-wall velocity profiles in LES while, similarly to equilibrium wall models, its cost remains independent of Reynolds number and is thus significantly lower compared to standard zonal or hybrid wall models. This work is funded by ONR Grant N00014-12-1-0582 (Dr. R. Joslin, program manager).
Mohruni, Amrifan Saladin; Yanis, Muhammad; Sharif, Safian; Yani, Irsyadi; Yuliwati, Erna; Ismail, Ahmad Fauzi; Shayfull, Zamree
2017-09-01
Thin-wall components as usually applied in the structural parts of aeronautical industry require significant challenges in machining. Unacceptable surface roughness can occur during machining of thin-wall. Titanium product such Ti6Al4V is mostly applied to get the appropriate surface texture in thin wall designed requirements. In this study, the comparison of the accuracy between Response Surface Methodology (RSM) and Artificial Neural Networks (ANN) in the prediction of surface roughness was conducted. Furthermore, the machining tests were carried out under Minimum Quantity Lubrication (MQL) using AlCrN-coated carbide tools. The use of Coconut oil as cutting fluids was also chosen in order to evaluate its performance when involved in end milling. This selection of cutting fluids is based on the better performance of oxidative stability than that of other vegetable based cutting fluids. The cutting speed, feed rate, radial and axial depth of cut were used as independent variables, while surface roughness is evaluated as the dependent variable or output. The results showed that the feed rate is the most significant factors in increasing the surface roughness value followed by the radial depth of cut and lastly the axial depth of cut. In contrary, the surface becomes smoother with increasing the cutting speed. From a comparison of both methods, the ANN model delivered a better accuracy than the RSM model.
Directory of Open Access Journals (Sweden)
G. Li
2018-02-01
Full Text Available Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/Cooney–Kim–Davis (CKD/Knopf–Pöschl–Shiraiwa (KPS methods, which has not been fully resolved in earlier studies. Here, we investigate the influence of surface roughness and local turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we derive and propose a critical height δc to evaluate turbulence effects in the design and analysis of coated-wall flow tube experiments. If a geometric coating thickness δg is larger than δc, the roughness elements of the coating may cause local turbulence and result in overestimation of the real uptake coefficient (γ. We further develop modified CKD/KPS methods (i.e., CKD-LT/KPS-LT to account for roughness-induced local turbulence effects. By combination of the original methods and their modified versions, the maximum error range of γCKD (derived with the CKD method or γKPS (derived with the KPS method can be quantified and finally γ can be constrained. When turbulence is generated, γCKD or γKPS can bear large difference compared to γ. Their difference becomes smaller for gas reactants with lower uptake (i.e., smaller γ and/or for a smaller ratio of the geometric coating thickness to the flow tube radius (δg ∕ R0. On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length, and flow velocity, to ensure not only unaffected laminar flow patterns but also other specific requirements for an
Kasem, Haytam; Cohen, Yossi
2017-08-04
Hairy adhesive systems involved in gecko locomotion have drawn the interest of many researchers regarding the development of bionic solutions for fast and reversible adhesive technologies. To date, despite extensive efforts to design gecko-inspired adhesive surfaces, adhesion and friction capacities are often evaluated using smooth and rigid counterfaces, in general glass, whereas most natural and artificial surfaces inevitably have a certain level of roughness. For that reason, in this study experiments tested the effects of the substrate roughness on the friction of bionic wale-shaped microstructures for gecko-like attachments. To this end, 12 substrates with different isotropic roughness were prepared using the same Epoxy material. Friction force was measured under various normal loads. It was concluded that classical roughness parameters, considered separately, are not appropriate to explain roughness-related variations in friction force. This has led us to develop a new integrative roughness parameter that combines characteristics of the surface. The parameter is capable of classifying the obtained experimental results in a readable way. An analytical model based on the experimental results has been developed to predict the variation of the friction force as a function of counterface roughness and applied normal load.
Turbulent flow and heat transfer in channels with combined rough and smooth surfaces
International Nuclear Information System (INIS)
Aytekin, A.
1978-01-01
A two-part experimental investigation is reported on the effects of transverse square rib roughening on fluid flow and heat transfer in channels with uniform and non-uniform boundary conditions. The first part of the experimental programme consisted of providing detailed measurements of mean and basic turbulent characteristics of fully developed flow in two rectangular ducts of aspect ratios 1.63 and 3.0. In each duct only one wall was roughened. In channels having low aspect ratios secondary flows play an important part in momentum transfer, and an interpretation of their effect on the measured Reynolds shear stress distribution has been attempted. In the second part of the experimental programme mean velocity and temperature profiles, friction factors and Stanton numbers were measured in an internally roughened pipe and annuli composed of a rough inner rod and either a smooth or a rough outer pipe. Heating was always applied on the outer surface. In all the geometries the mean velocities near the rough walls were found to be represented by logarithmic straight lines. The gradients of these lines were independent of Reynolds number but differed for various geometries. The mean temperature profiles, measured in the rough pipe and the fully rough annulus, showed that these could also be represented by logarithmic straight lines, but the slopes of these profiles were markedly different from those of the velocity profiles. (author)
Beam line from straight-section 16
CERN PhotoLab
1971-01-01
The start of a long trail. The beam line from straight-section 16, where protons are fast ejected, is seen at the point where it crosses the Linac shielding wall as it leaves the PS en route to the ISR.
International Nuclear Information System (INIS)
Yang Guangming; Li Ling; Jiang Jinhe; Yang Yunhui
2012-01-01
Gold nanotube arrays of rough and porous wall has been synthesized by direct electrodeposition with cyclic voltammetry utilizing anodic aluminum oxide template (AAO) and polycarbonate membrane (PC) during short time (only 3 min and 2 min, respectively). The mechanism of the direct electrodeposition of gold nanotube arrays by cyclic voltammetry (CV) has been discussed. The morphological characterizations of the gold nanotube arrays have been investigated by scanning electron microscopy (SEM). A simultaneous determination of ascorbic acid (AA) and uric acid (UA) by differential pulse voltammetry (DPV) was constructed by attaching gold nanotube arrays (using AAO) onto the surface of a glassy carbon electrode (GCE). The electrochemical behavior of AA and UA at this modified electrode has been studied by CV and differential pulse voltammetry (DPV). The sensor offers an excellent response for AA and UA and the linear response range for AA and UA were 1.02 × 10 −7 –5.23 × 10 −4 mol L −1 and 1.43 × 10 −7 –4.64 × 10 −4 mol L −1 , the detection limits were 1.12 × 10 −8 mol L −1 and 2.24 × 10 −8 mol L −1 , respectively. This sensor shows good regeneration, stability and selectivity and has been used for the determination of AA and UA in real human urine and serum samples with satisfied results. - Graphical abstract: The schematic diagram of formation of Au nanotube arrays (a) and the stepwise procedure of the sensor (b). Highlights: ► Gold nanotubes array has been synthesized by cyclic voltammetry. ► The mechanism of deposition of gold nanotube has been discussed. ► A determination of ascorbic acid and uric acid was constructed by gold array. ► A satisfied determination of samples can be obtained by this sensor.
Energy Technology Data Exchange (ETDEWEB)
Yang Guangming, E-mail: yangguangmingbs@126.com [Department of Resources and Environment, Baoshan University, Baoshan 678000 (China); Ling, Li [Department of Resources and Environment, Baoshan University, Baoshan 678000 (China); Jinhe, Jiang; Yunhui, Yang [College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092 (China)
2012-08-01
Gold nanotube arrays of rough and porous wall has been synthesized by direct electrodeposition with cyclic voltammetry utilizing anodic aluminum oxide template (AAO) and polycarbonate membrane (PC) during short time (only 3 min and 2 min, respectively). The mechanism of the direct electrodeposition of gold nanotube arrays by cyclic voltammetry (CV) has been discussed. The morphological characterizations of the gold nanotube arrays have been investigated by scanning electron microscopy (SEM). A simultaneous determination of ascorbic acid (AA) and uric acid (UA) by differential pulse voltammetry (DPV) was constructed by attaching gold nanotube arrays (using AAO) onto the surface of a glassy carbon electrode (GCE). The electrochemical behavior of AA and UA at this modified electrode has been studied by CV and differential pulse voltammetry (DPV). The sensor offers an excellent response for AA and UA and the linear response range for AA and UA were 1.02 Multiplication-Sign 10{sup -7}-5.23 Multiplication-Sign 10{sup -4} mol L{sup -1} and 1.43 Multiplication-Sign 10{sup -7}-4.64 Multiplication-Sign 10{sup -4} mol L{sup -1}, the detection limits were 1.12 Multiplication-Sign 10{sup -8} mol L{sup -1} and 2.24 Multiplication-Sign 10{sup -8} mol L{sup -1}, respectively. This sensor shows good regeneration, stability and selectivity and has been used for the determination of AA and UA in real human urine and serum samples with satisfied results. - Graphical abstract: The schematic diagram of formation of Au nanotube arrays (a) and the stepwise procedure of the sensor (b). Highlights: Black-Right-Pointing-Pointer Gold nanotubes array has been synthesized by cyclic voltammetry. Black-Right-Pointing-Pointer The mechanism of deposition of gold nanotube has been discussed. Black-Right-Pointing-Pointer A determination of ascorbic acid and uric acid was constructed by gold array. Black-Right-Pointing-Pointer A satisfied determination of samples can be obtained by this sensor.
Rough Finite State Automata and Rough Languages
Arulprakasam, R.; Perumal, R.; Radhakrishnan, M.; Dare, V. R.
2018-04-01
Sumita Basu [1, 2] recently introduced the concept of a rough finite state (semi)automaton, rough grammar and rough languages. Motivated by the work of [1, 2], in this paper, we investigate some closure properties of rough regular languages and establish the equivalence between the classes of rough languages generated by rough grammar and the classes of rough regular languages accepted by rough finite automaton.
Khozani, Zohreh Sheikh; Bonakdari, Hossein; Zaji, Amir Hossein
2016-01-01
Two new soft computing models, namely genetic programming (GP) and genetic artificial algorithm (GAA) neural network (a combination of modified genetic algorithm and artificial neural network methods) were developed in order to predict the percentage of shear force in a rectangular channel with non-homogeneous roughness. The ability of these methods to estimate the percentage of shear force was investigated. Moreover, the independent parameters' effectiveness in predicting the percentage of shear force was determined using sensitivity analysis. According to the results, the GP model demonstrated superior performance to the GAA model. A comparison was also made between the GP program determined as the best model and five equations obtained in prior research. The GP model with the lowest error values (root mean square error ((RMSE) of 0.0515) had the best function compared with the other equations presented for rough and smooth channels as well as smooth ducts. The equation proposed for rectangular channels with rough boundaries (RMSE of 0.0642) outperformed the prior equations for smooth boundaries.
Energy Technology Data Exchange (ETDEWEB)
Steinbuch, R [Fachhochschule fuer Technik und Wirtschaft Reutlingen (Germany). Fachbereich Maschinenbau
1998-11-01
Methods for calculation of critical, circumferential through-wall crack lengths in pipes have been developed and verified by several research projects. In applications during the last few years it has been found that the force or displacement-controlled loads have to be considered separately, and this approach was integrated into the recent methods. Methods so far assumed cracks to be located in welds joining straight pipes. But this approach starts from an incomplete picture of reality, as with today`s technology, circumferential welds are less frequent in straight pipes and much more frequent in pipework of other geometry, as for instance in welds joining straight pipes and bends, or bends with longer legs, nozzles, or T-pieces. The non-linear FEM parameter study presented in the paper, covering cases with internal pressure of pipes and one-dimensional bending loads, is based on current geometries of pipework in the primary and secondary loops of industrial plants and compares the conditions induced by circumferential through-wall cracks in welds joining only straight pipes and in those joining bended and straight pipes. At the relevant, displacement-controlled bending loads due to hampered thermal expansion of the pipe system, the critical through-wall cracks lengths occurring in pipe-to-bend welds are of about the same size and importance as those in pipe-to-pipe welds. As for the case of force-controlled loads, the technical codes calculate more serious effects and require lower bending load limits. Within the range of admissible loads given in the codes, the critical through-wall crack lengths occurring in pipe-to-bend welds are similar in size to those in straight pipe welds. It is therefore a conservative or realistic approach to apply the values determined for critical through-wall crack lengths in pipe-to-pipe joints also to pipe-to-bend welds. (orig./CB) [Deutsch] Verfahren zur Berechnung kritischer Umfangdurchrisslaengen in Rohrleitungen wurden in
Straight scaling FFAG beam line
International Nuclear Information System (INIS)
Lagrange, J.-B.; Planche, T.; Yamakawa, E.; Uesugi, T.; Ishi, Y.; Kuriyama, Y.; Qin, B.; Okabe, K.; Mori, Y.
2012-01-01
Fixed field alternating gradient (FFAG) accelerators are recently subject to a strong revival. They are usually designed in a circular shape; however, it would be an asset to guide particles with no overall bend in this type of accelerator. An analytical development of a straight FFAG cell which keeps zero-chromaticity is presented here. A magnetic field law is thus obtained, called “straight scaling law”, and an experiment has been conducted to confirm this zero-chromatic law. A straight scaling FFAG prototype has been designed and manufactured, and horizontal phase advances of two different energies are measured. Results are analyzed to clarify the straight scaling law.
Straight scaling FFAG beam line
Lagrange, J.-B.; Planche, T.; Yamakawa, E.; Uesugi, T.; Ishi, Y.; Kuriyama, Y.; Qin, B.; Okabe, K.; Mori, Y.
2012-11-01
Fixed field alternating gradient (FFAG) accelerators are recently subject to a strong revival. They are usually designed in a circular shape; however, it would be an asset to guide particles with no overall bend in this type of accelerator. An analytical development of a straight FFAG cell which keeps zero-chromaticity is presented here. A magnetic field law is thus obtained, called "straight scaling law", and an experiment has been conducted to confirm this zero-chromatic law. A straight scaling FFAG prototype has been designed and manufactured, and horizontal phase advances of two different energies are measured. Results are analyzed to clarify the straight scaling law.
Standing "Straight" up to Homophobia: Straight Allies' Involvement in GSAs
Lapointe, Alicia Anne
2015-01-01
This qualitative study captures the experiences of four straight allies' and one gay youth involvement in gay--straight alliances (GSAs) at their Ontario, Canada, high schools. Participants' motivations for becoming GSA members and their roles as allies are examined. Queer theoretical perspectives, as espoused by Britzman (1995, 1998) and Linville…
Straight Ahead in Microgravity
Wood, S. J.; Vanya, R. D.; Clement, G.
2014-01-01
This joint ESA-NASA study will address adaptive changes in spatial orientation related to the subjective straight ahead, and the use of a vibrotactile sensory aid to reduce perceptual errors. The study will be conducted before and after long-duration expeditions to the International Space Station (ISS) to examine how spatial processing of target location is altered following exposure to microgravity. This project specifically addresses the sensorimotor research gap "What are the changes in sensorimotor function over the course of a mission?" Six ISS crewmembers will be requested to participate in three preflight sessions (between 120 and 60 days prior to launch) and then three postflight sessions on R+0/1 day, R+4 +/-2 days, and R+8 +/-2 days. The three specific aims include: (a) fixation of actual and imagined target locations at different distances; (b) directed eye and arm movements along different spatial reference frames; and (c) the vestibulo-ocular reflex during translation motion with fixation targets at different distances. These measures will be compared between upright and tilted conditions. Measures will then be compared with and without a vibrotactile sensory aid that indicates how far one has tilted relative to the straight-ahead direction. The flight study was been approved by the medical review boards and will be implemented in the upcoming Informed Crew Briefings to solicit flight subject participation. Preliminary data has been recorded on 6 subjects during parabolic flight to examine the spatial coding of eye movements during roll tilt relative to perceived orientations while free-floating during the microgravity phase of parabolic flight or during head tilt in normal gravity. Binocular videographic recordings obtained in darkness allowed us to quantify the mean deviations in gaze trajectories along both horizontal and vertical coordinates relative to the aircraft and head orientations. During some parabolas, a vibrotactile sensory aid provided
Towards predictive models for transitionally rough surfaces
Abderrahaman-Elena, Nabil; Garcia-Mayoral, Ricardo
2017-11-01
We analyze and model the previously presented decomposition for flow variables in DNS of turbulence over transitionally rough surfaces. The flow is decomposed into two contributions: one produced by the overlying turbulence, which has no footprint of the surface texture, and one induced by the roughness, which is essentially the time-averaged flow around the surface obstacles, but modulated in amplitude by the first component. The roughness-induced component closely resembles the laminar steady flow around the roughness elements at the same non-dimensional roughness size. For small - yet transitionally rough - textures, the roughness-free component is essentially the same as over a smooth wall. Based on these findings, we propose predictive models for the onset of the transitionally rough regime. Project supported by the Engineering and Physical Sciences Research Council (EPSRC).
Diffraction at a Straight Edge
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 5. Diffraction at a Straight Edge: A Gem from Sommerfeld's Work in Classical Physics. Rajaram Nityananda. General Article Volume 20 Issue 5 May 2015 pp 389-400 ...
Surface roughness effects on turbulent Couette flow
Lee, Young Mo; Lee, Jae Hwa
2017-11-01
Direct numerical simulation of a turbulent Couette flow with two-dimensional (2-D) rod roughness is performed to examine the effects of the surface roughness. The Reynolds number based on the channel centerline laminar velocity (Uco) and channel half height (h) is Re =7200. The 2-D rods are periodically arranged with a streamwise pitch of λ = 8 k on the bottom wall, and the roughness height is k = 0.12 h. It is shown that the wall-normal extent for the logarithmic layer is significantly shortened in the rough-wall turbulent Couette flow, compared to a turbulent Couette flow with smooth wall. Although the Reynolds stresses are increased in a turbulent channel flow with surface roughness in the outer layer due to large-scale ejection motions produced by the 2-D rods, those of the rough-wall Couette flow are decreased. Isosurfaces of the u-structures averaged in time suggest that the decrease of the turbulent activity near the centerline is associated with weakened large-scale counter-rotating roll modes by the surface roughness. This research was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2017R1D1A1A09000537) and the Ministry of Science, ICT & Future Planning (NRF-2017R1A5A1015311).
Capillary Condensation in Pores with Rough Walls:
Czech Academy of Sciences Publication Activity Database
Bryk, P.; Rżysko, W.; Malijevský, Alexandr; Sokołowski, S.
2007-01-01
Roč. 313, č. 1 (2007), s. 41-52 ISSN 0021-9797 Grant - others:TOK(XE) 509249 Institutional research plan: CEZ:AV0Z40720504 Source of funding: R - rámcový projekt EK Keywords : adsorption * pore * capillary condensation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.309, year: 2007
Turbulent flow with suction in smooth and rough pipes
International Nuclear Information System (INIS)
Verdier, Andre.
1977-11-01
It concerns an experimental study of turbulent flow inside a pipe with rough and porous wall and suction applied through it. The first part recall the basic knowledge concerning the turbulent flow with roughness. In second part statistical equations of fluid wall stress are written in the case of a permeable rough wall, in order to underline the respective role played by viscosity and pressure terms. In the third part the dynamic equilibrium of the flow is experimentally undertaken in the smooth and rough range with and without wall suction. Some empirical formulae are proposed for the mean velocity profiles in the inertial range and for friction velocity with suction. In the case of the sand roughness used, it does not seem that critical Reynolds number of transition from smooth to rough range is varied [fr
Straight nearness spaces | Bentley | Quaestiones Mathematicae
African Journals Online (AJOL)
Straight spaces are spaces for which a continuous map defined on the space which is uniformly continuous on each set of a finite closed cover is then uniformly continuous on the whole space. Previously, straight spaces have been studied in the setting of metric spaces. In this paper, we present a study of straight spaces in ...
Straightness measurement of large machine guideways
Directory of Open Access Journals (Sweden)
W. Ptaszyñski
2011-10-01
Full Text Available This paper shows the guideway types of large machines and describes problems with their straightness measurement. A short description of straightness measurement methods and the results of investigation in straightness of 10 meter long guideways of a CNC machine by means of the XL-10 Renishaw interferometer are also presented.
Straight sinus: ultrastructural analysis aimed at surgical tumor resection.
Amato, Marcelo Campos Moraes; Tirapelli, Luis Fernando; Carlotti, Carlos Gilberto; Colli, Benedicto Oscar
2016-08-01
OBJECTIVE Accurate knowledge of the anatomy of the straight sinus (SS) is relevant for surgical purposes. During one surgical procedure involving the removal of part of the SS wall, the authors observed that the venous blood flow was maintained in the SS, possibly through a vein-like structure within the dural sinus or dural multiple layers. This observation and its divergence from descriptions of the histological features of the SS walls motivated the present study. The authors aimed to investigate whether it is possible to dissect the SS walls while keeping the lumen intact, and to describe the histological and ultrastructural composition of the SS wall. METHODS A total of 22 cadaveric specimens were used. The SS was divided into three portions: anterior, middle, and posterior. The characteristics of the SS walls were analyzed, and the feasibility of dissecting them while keeping the SS lumen intact was assessed. The thickness and the number of collagen fibers and other tissues in the SS walls were compared with the same variables in other venous sinuses. Masson's trichrome and Verhoeff's stains were used to assess collagen and elastic fibers, respectively. The data were analyzed using Zeiss image analysis software (KS400). RESULTS A vein-like structure independent of the SS walls was found in at least one of the portions of the SS in 8 of 22 samples (36.36%). The inferior wall could be delaminated in at least one portion in 21 of 22 samples (95.45%), whereas the lateral walls could seldom be delaminated. The inferior wall of the SS was thicker (p < 0.05) and exhibited less collagen and greater amounts of other tissues-including elastic fibers, connective tissue, blood vessels, and nerve fibers (p < 0.05)-compared with the lateral walls. Transmission electron microscopy revealed the presence of muscle fibers at a level deeper than that of the subendothelial connective tissue in the inferior wall of the SS, extending from its junction with the great cerebral vein
Ratcheting failure of pressurised straight pipes and elbows under reversed bending
International Nuclear Information System (INIS)
Vishnuvardhan, S.; Raghava, G.; Gandhi, P.; Saravanan, M.; Goyal, Sumit; Arora, Punit; Gupta, Suneel K.; Bhasin, Vivek
2013-01-01
Ratcheting studies were carried out on Type 304LN stainless steel straight pipes and elbows subjected to steady internal pressure and cyclic bending load. The internal pressure for all the straight pipes was 35 MPa and in the case of elbows the internal pressure was varied for different elbows, ranging from 27.6 MPa to 39.2 MPa. Cyclic bending load was applied on the specimens by subjecting them to different levels of load-line displacement. The specimens have undergone significant ratchet swelling (ballooning), ovalization and consequent thinning of the cross-section during ratcheting. The straight pipes failed either by occurrence of through-wall crack accompanied by simultaneous ballooning, or bursting with simultaneous ballooning. All the elbows failed by occurrence of through-wall crack accompanied by simultaneous ballooning. Ratcheting behaviour of straight pipes and elbows were compared and it was generally inferred that ratcheting was more pronounced in straight pipes than in elbows. -- Graphical abstract: Strain history for the specimen QCE-RAT-6-L1. Highlights: • Studies were carried out under combined internal pressure and cyclic bending. • Ratcheting strains were measured at critical locations of the specimens. • Quantified the percentage of ballooning, ovalization and reduction in thickness. • Modes of ratcheting failure of straight pipes and elbows are studied. • Inferred that ratcheting is more pronounced in straight pipes than in elbows
Barros, Julio; Flack, Karen; Schultz, Michael
2017-11-01
Real-world engineering systems which feature either external or internal wall-bounded turbulent flow are routinely affected by surface roughness. This gives rise to performance degradation in the form of increased drag or head loss. However, at present there is no reliable means to predict these performance losses based upon the roughness topography alone. This work takes a systematic approach by generating random surface roughness in which the surface statistics are closely controlled. Skin friction and roughness function results will be presented for two groups of these rough surfaces. The first group is Gaussian (i.e. zero skewness) in which the root-mean-square roughness height (krms) is varied. The second group has a fixed krms, and the skewness is varied from approximately -1 to +1. The effect of the roughness amplitude and skewness on the skin friction will be discussed. Particular attention will be paid to the effect of these parameters on the roughness function in the transitionally-rough flow regime. For example, the role these parameters play in the monotonic or inflectional nature of the roughness function will be addressed. Future research into the details of the turbulence structure over these rough surfaces will also be outlined. Research funded by U.S. Office of Naval Research (ONR).
Modifications in straight wire treatment.
Cardona, Alvin
2010-01-01
Orthodontic treatments have been modified with each new generation of clinicians. Today the emphasis is on facial esthetics and healthy temporomandibular joints. With orthopedic treatment, we can develop dental arches to get the necessary space to align the teeth and we can reach adequate function and esthetics, all within relatively good stability. By combining two-phase treatment with low friction fixed orthodontics and super elastic wires we produce light but continuous forces and we can provide better treatment than before. These types of forces cause physiological and functional orthopedic orthodontic reactions. The purpose of this article is to demonstrate our fixed orthopedic and orthodontic approach called "Modified Straight Wire" or "Physiologic Arch Technique." This technique is very successful with our patients because it can exert slow and continuous forces with minimal patient cooperation.
Microscopic Holography for flow over rough plate
Talapatra, Siddharth; Hong, Jiarong; Lu, Yuan; Katz, Joseph
2008-11-01
Our objective is to measure the near wall flow structures in a turbulent channel flow over a rough wall. In-line microscopic holographic PIV can resolve the 3-D flow field in a small sample volume, but recording holograms through a rough surface is a challenge. To solve this problem, we match the refractive indices of the fluid with that of the wall. Proof of concept tests involve an acrylic plate containing uniformly distributed, closely packed 0.45mm high pyramids with slope angle of 22^^o located within a concentrated sodium iodide solution. Holograms recorded by a 4864 x 3248 pixel digital camera at 10X magnification provide a field of view of 3.47mm x 2.32mm and pixel resolution of 0.714 μm. Due to index matching, reconstructed seed particles can be clearly seen over the entire volume, with only faint traces with the rough wall that can be removed. Planned experiments will be performed in a 20 x 5 cm rectangular channel with the top and bottom plates having the same roughness as the sample plate.
Defect Depth Measurement of Straight Pipe Specimen Using Shearography
International Nuclear Information System (INIS)
Chang, Ho Seob; Kim, Kyung Suk
2012-01-01
In the nuclear industry, wall thinning defect of straight pipe occur the enormous loss in life evaluation and safety evaluation. To use non-destructive technique, we measure deformation, vibration, defect evaluation. But, this techniques are a weak that is the measurement of the wide area is difficult and the time is caught long. In the secondary side of nuclear power plants mostly used steel pipe, artificiality wall thinning defect make in the side and different thickness make to the each other, wall thinning defect part of deformation measure by using shearography. In addition, optical measurement through deformation, vibration, defect evaluation evaluate pipe and thickness defects of pressure vessel is to evaluate quantitatively. By shearography interferometry to measure the pipe's internal wall thinning defect and the variation of pressure use the proposed technique, the quantitative defect is to evaluate the thickness of the surplus. The amount of deformation use thickness of surplus prediction of the actual thickness defect and approximately 7 percent error by ensure reliability. According to pressure the amount of deformation and the thickness of the surplus through DB construction, nuclear power plant pipe use wall thinning part soundness evaluation. In this study, pressure vessel of thickness defect measure proposed nuclear pipe of wall thinning defect prediction and integrity assessment technology development. As a basic research defected theory and experiment, pressure vessel of advanced stability and soundness and maintainability is expected to contribute foundation establishment
Curved-straight neutron guide system with uniform spatial intensity distribution
International Nuclear Information System (INIS)
Mildner, D.F.R.; Cook, J.C.
2008-01-01
The spatial intensity distribution of neutrons emerging from a curved guide is asymmetric, and straight guide sections are sometimes appended to curved guides to make the intensity distribution more nearly uniform. For idealized uniform illumination and in the perfect reflectivity approximation, the spatial-angular acceptance at the exit of the combination can be made exactly uniform for a range of long wavelengths by using a sufficiently long straight section, together with a curved guide whose outer wall coating has a critical angle slightly greater than those of the other guide walls. We refer to this as a 'phase space tailoring guide' where the coatings on the inner wall and straight section are used to define the required divergence at the end of the guide. Increasing the critical angle of the outer wall of the curved section reduces the characteristic wavelength of the curved guide as well as the wavelength at which ideal uniformity can be obtained. The outer wall coating need only be of sufficiently high critical angle to fill the transmittable phase space area of the straight guide uniformly to adequately short wavelength
Assembling the LHC short straight sections
Maximilien Brice
2005-01-01
The building where the short straight sections are being assembled, was often called ‘Lego Land’ by the workers because of the wide variety of sets of magnets and cryostats. Short straight sections contain magnets for manipulating the beam inside cryostats with liquid helium to keep the magnets at a cool 1.9 K (-271.3°C).
Rough horizontal plates: heat transfer and hysteresis
Energy Technology Data Exchange (ETDEWEB)
Tisserand, J-C; Gasteuil, Y; Pabiou, H; Castaing, B; Chilla, F [Universite de Lyon, ENS Lyon, CNRS, 46 Allee d' ltalie, 69364 Lyon Cedex 7 (France); Creyssels, M [LMFA, CNRS, Ecole Centrale Lyon, 69134 Ecully Cedex (France); Gibert, M, E-mail: mathieu.creyssels@ec-lyon.fr [Also at MPI-DS (LFPN) Gottingen (Germany)
2011-12-22
To investigate the influence of a rough-wall boundary layer on turbulent heat transport, an experiment of high-Rayleigh convection in water is carried out in a Rayleigh-Benard cell with a rough lower plate and a smooth upper plate. A transition in the heat transport is observed when the thermal boundary layer thickness becomes comparable to or smaller than the roughness height. Besides, at larger Rayleigh numbers than the threshold value, heat transport is found to be increased up to 60%. This enhancement cannot be explained simply by an increase in the contact area of the rough surface since the contact area is increased only by a factor of 40%. Finally, a simple model is proposed to explain the enhanced heat transport.
Surface correlations of hydrodynamic drag for transitionally rough engineering surfaces
Thakkar, Manan; Busse, Angela; Sandham, Neil
2017-02-01
Rough surfaces are usually characterised by a single equivalent sand-grain roughness height scale that typically needs to be determined from laboratory experiments. Recently, this method has been complemented by a direct numerical simulation approach, whereby representative surfaces can be scanned and the roughness effects computed over a range of Reynolds number. This development raises the prospect over the coming years of having enough data for different types of rough surfaces to be able to relate surface characteristics to roughness effects, such as the roughness function that quantifies the downward displacement of the logarithmic law of the wall. In the present contribution, we use simulation data for 17 irregular surfaces at the same friction Reynolds number, for which they are in the transitionally rough regime. All surfaces are scaled to the same physical roughness height. Mean streamwise velocity profiles show a wide range of roughness function values, while the velocity defect profiles show a good collapse. Profile peaks of the turbulent kinetic energy also vary depending on the surface. We then consider which surface properties are important and how new properties can be incorporated into an empirical model, the accuracy of which can then be tested. Optimised models with several roughness parameters are systematically developed for the roughness function and profile peak turbulent kinetic energy. In determining the roughness function, besides the known parameters of solidity (or frontal area ratio) and skewness, it is shown that the streamwise correlation length and the root-mean-square roughness height are also significant. The peak turbulent kinetic energy is determined by the skewness and root-mean-square roughness height, along with the mean forward-facing surface angle and spanwise effective slope. The results suggest feasibility of relating rough-wall flow properties (throughout the range from hydrodynamically smooth to fully rough) to surface
Weighted straight skeletons in the plane.
Biedl, Therese; Held, Martin; Huber, Stefan; Kaaser, Dominik; Palfrader, Peter
2015-02-01
We investigate weighted straight skeletons from a geometric, graph-theoretical, and combinatorial point of view. We start with a thorough definition and shed light on some ambiguity issues in the procedural definition. We investigate the geometry, combinatorics, and topology of faces and the roof model, and we discuss in which cases a weighted straight skeleton is connected. Finally, we show that the weighted straight skeleton of even a simple polygon may be non-planar and may contain cycles, and we discuss under which restrictions on the weights and/or the input polygon the weighted straight skeleton still behaves similar to its unweighted counterpart. In particular, we obtain a non-procedural description and a linear-time construction algorithm for the straight skeleton of strictly convex polygons with arbitrary weights.
Straight sinus thrombosis during neurosurgical operation.
Kawano, Hiroto; Nitta, Naoki; Nozaki, Kazuhiko
2016-01-01
Perioperative straight sinus thrombosis is extremely rare. A 59-year-old female was admitted to our department because of incidentally found small anterior cerebral artery (A1) aneurysm with microbleeding. After clipping the cerebral aneurysm, she had delayed emergence from anesthesia, total aphasia, and right hemiparesis. Fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) of the head showed hyperintensity in the bilateral caudate nuclei, putamina, and thalami, and computed tomography of the head showed a hyperdense straight sinus, suggesting straight sinus thrombosis. Her neurologic symptoms improved gradually, and she achieved a full clinical recovery, with radiological evidence of recanalization of the straight sinus at follow-up. The possibility of straight sinus thrombosis should be considered in postoperative patients with unexplained postoperative deficits when MRI demonstrates hyperintensity in the bilateral basal ganglia and thalami on FLAIR signal images.
Measurement of surface roughness
DEFF Research Database (Denmark)
De Chiffre, Leonardo
This document is used in connection with two 3 hours laboratory exercises that are part of the course GEOMETRICAL METROLOGY AND MACHINE TESTING. The laboratories include a demonstration of the function of roughness measuring instruments plus a series of exercises illustrating roughness measurement...
Rough multiple objective decision making
Xu, Jiuping
2011-01-01
Rough Set TheoryBasic concepts and properties of rough sets Rough Membership Rough Intervals Rough FunctionApplications of Rough SetsMultiple Objective Rough Decision Making Reverse Logistics Problem with Rough Interval Parameters MODM based Rough Approximation for Feasible RegionEVRMCCRMDCRM Reverse Logistics Network Design Problem of Suji Renewable Resource MarketBilevel Multiple Objective Rough Decision Making Hierarchical Supply Chain Planning Problem with Rough Interval Parameters Bilevel Decision Making ModelBL-EVRM BL-CCRMBL-DCRMApplication to Supply Chain Planning of Mianyang Co., LtdStochastic Multiple Objective Rough Decision Multi-Objective Resource-Constrained Project Scheduling UnderRough Random EnvironmentRandom Variable Stochastic EVRM Stochastic CCRM Stochastic DCRM Multi-Objective rc-PSP/mM/Ro-Ra for Longtan Hydropower StationFuzzy Multiple Objective Rough Decision Making Allocation Problem under Fuzzy Environment Fuzzy Variable Fu-EVRM Fu-CCRM Fu-DCRM Earth-Rock Work Allocation Problem.
International Nuclear Information System (INIS)
De Marchis, M.; Napoli, E.
2012-01-01
Highlights: ► 3D irregular rough surfaces produce higher effects than those observed over 2D. ► Effective slope is a geometrical parameter representative of the roughness effects. ► 3D rough surfaces enhance the turbulence isotropization. ► 2D and 3D irregular roughness partially support the wall similarity. ► Irregular rough surfaces shear some features with regular rough walls. - Abstract: Wall-resolved Large Eddy Simulation of fully developed turbulent channel flows over two different rough surfaces is performed to investigate on the effects of irregular 2D and 3D roughness on the turbulence. The two geometries are obtained through the superimposition of sinusoidal functions having random amplitudes and different wave lengths. In the 2D configuration the irregular shape in the longitudinal direction is replicated in the transverse one, while in the 3D case the sinusoidal functions are generated both in streamwise and spanwise directions. Both channel walls are roughened in such a way as to obtain surfaces with statistically equivalent roughness height, but different shapes. In order to compare the turbulence properties over the two rough walls and to analyse the differences with a smooth wall, the simulations are performed at the same Reynolds number Re τ = 395. The same mean roughness height h = 0.05δ (δ the half channel height) is used for the rough walls. The roughness function obtained with the 3D roughness is larger than in the 2D case, although the two walls share the same mean height. Thus, the considered irregular 3D roughness is more effective in reducing the flow velocity with respect to the 2D roughness, coherently with the literature results that identified a clear dependence of the roughness function on the effective slope (see ), higher in the generated 3D rough wall. The analysis of higher-order statistics shows that the effects of the roughness, independently on its two- or three-dimensional shape, are mainly confined in the inner
A Faster Algorithm for Computing Straight Skeletons
Cheng, Siu-Wing
2014-09-01
We present a new algorithm for computing the straight skeleton of a polygon. For a polygon with n vertices, among which r are reflex vertices, we give a deterministic algorithm that reduces the straight skeleton computation to a motorcycle graph computation in O(n (logn)logr) time. It improves on the previously best known algorithm for this reduction, which is randomized, and runs in expected O(n√h+1log2n) time for a polygon with h holes. Using known motorcycle graph algorithms, our result yields improved time bounds for computing straight skeletons. In particular, we can compute the straight skeleton of a non-degenerate polygon in O(n (logn) logr + r 4/3 + ε ) time for any ε > 0. On degenerate input, our time bound increases to O(n (logn) logr + r 17/11 + ε ).
A Faster Algorithm for Computing Straight Skeletons
Mencel, Liam A.
2014-05-06
We present a new algorithm for computing the straight skeleton of a polygon. For a polygon with n vertices, among which r are reflex vertices, we give a deterministic algorithm that reduces the straight skeleton computation to a motorcycle graph computation in O(n (log n) log r) time. It improves on the previously best known algorithm for this reduction, which is randomised, and runs in expected O(n √(h+1) log² n) time for a polygon with h holes. Using known motorcycle graph algorithms, our result yields improved time bounds for computing straight skeletons. In particular, we can compute the straight skeleton of a non-degenerate polygon in O(n (log n) log r + r^(4/3 + ε)) time for any ε > 0. On degenerate input, our time bound increases to O(n (log n) log r + r^(17/11 + ε))
SPS, preassembly of short straight sections
1975-01-01
Short straight sections were preassembled with their vacuum chambers, ready for installation in the SPS. Here we see two, containing sextupoles for chromaticity adjustment. See also 7501017, 7501018, and Annual Report 1976, p.174.
SPS, short straight section with sextupole
CERN PhotoLab
1975-01-01
Short straight sections were preassembled with their vacuum chambers, ready for installation in the SPS. This one contains a sextupole for chromaticity adjustment. See also 7501017, 7501009X, and Annual Report 1974, p.174.
A Faster Algorithm for Computing Straight Skeletons
Cheng, Siu-Wing; Mencel, Liam A.; Vigneron, Antoine E.
2014-01-01
We present a new algorithm for computing the straight skeleton of a polygon. For a polygon with n vertices, among which r are reflex vertices, we give a deterministic algorithm that reduces the straight skeleton computation to a motorcycle graph computation in O(n (logn)logr) time. It improves on the previously best known algorithm for this reduction, which is randomized, and runs in expected O(n√h+1log2n) time for a polygon with h holes. Using known motorcycle graph algorithms, our result yields improved time bounds for computing straight skeletons. In particular, we can compute the straight skeleton of a non-degenerate polygon in O(n (logn) logr + r 4/3 + ε ) time for any ε > 0. On degenerate input, our time bound increases to O(n (logn) logr + r 17/11 + ε ).
Tetrahedron equations and the relativistic S-matrix of straight-strings in 2+1-dimensions
International Nuclear Information System (INIS)
Zamolodchikov, A.B.
1981-01-01
The quantum S-matrix theory of straight-strings (infinite one-dimensioanl objects like straight domain walls) in 2 + 1-dimensions is considered. The S-matrix is supposed to be purely elastic and factorized. The tetrahedron equations (which are the factorization conditions) are investigated for the special two-colour model. The relativistic three-string S-matrix, which apparently satisfies this tetrahedron equation, is proposed. (orig.)
An intermittency model for predicting roughness induced transition
Ge, Xuan; Durbin, Paul
2014-11-01
An extended model for roughness-induced transition is proposed based on an intermittency transport equation for RANS modeling formulated in local variables. To predict roughness effects in the fully turbulent boundary layer, published boundary conditions for k and ω are used, which depend on the equivalent sand grain roughness height, and account for the effective displacement of wall distance origin. Similarly in our approach, wall distance in the transition model for smooth surfaces is modified by an effective origin, which depends on roughness. Flat plate test cases are computed to show that the proposed model is able to predict the transition onset in agreement with a data correlation of transition location versus roughness height, Reynolds number, and inlet turbulence intensity. Experimental data for a turbine cascade are compared with the predicted results to validate the applicability of the proposed model. Supported by NSF Award Number 1228195.
International Nuclear Information System (INIS)
Cheng, Xiang; Wang, Zhigang; Yamazaki, Kazuo; Nakamoto, Kazuo
2010-01-01
One of the biggest challenges for mechanical micro/nano milling is the design and fabrication of high precision and high efficiency micro milling tools. Commercially available micro milling tools are either too expensive (around several hundred US dollars) or simply made from downsizing of macro milling tools, which is sometimes not appropriate for the specific micro/nano milling requirements. So the design and fabrication of custom micro milling tools are necessary. In this paper, a micro straight edge endmill (SEE) is designed. Static and dynamic FEM analyses have been done for the SEEs with different rake angles trying to identify their stiffness and natural frequencies. By wire electrical discharge machining (WEDM), the SEEs made of polycrystalline diamond (PCD) with three different rake angles have been fabricated. The evaluation milling on tungsten carbide (WC) and silicon wafer have processed on a nano milling center. Experimental results show the SEEs have a good ability to simultaneously micro/nano milling of both the side and bottom surfaces with submicron surface roughness, and the SEE has high accuracy for large aspect ratio thin wall machining. The milling experiments on silicon wafer have successfully demonstrated that ductile mode machining was achieved and the coolant played an important role in silicon wafer milling
26 CFR 1.167(b)-1 - Straight line method.
2010-04-01
... 26 Internal Revenue 2 2010-04-01 2010-04-01 false Straight line method. 1.167(b)-1 Section 1.167(b... Straight line method. (a) In general. Under the straight line method the cost or other basis of the... may be reduced to a percentage or fraction. The straight line method may be used in determining a...
Effect of truncated cone roughness element density on hydrodynamic drag
Womack, Kristofer; Schultz, Michael; Meneveau, Charles
2017-11-01
An experimental study was conducted on rough-wall, turbulent boundary layer flow with roughness elements whose idealized shape model barnacles that cause hydrodynamic drag in many applications. Varying planform densities of truncated cone roughness elements were investigated. Element densities studied ranged from 10% to 79%. Detailed turbulent boundary layer velocity statistics were recorded with a two-component LDV system on a three-axis traverse. Hydrodynamic roughness length (z0) and skin-friction coefficient (Cf) were determined and compared with the estimates from existing roughness element drag prediction models including Macdonald et al. (1998) and other recent models. The roughness elements used in this work model idealized barnacles, so implications of this data set for ship powering are considered. This research was supported by the Office of Naval Research and by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.
International Nuclear Information System (INIS)
Rady, E.A.; Kozae, A.M.; Abd El-Monsef, M.M.E.
2004-01-01
The process of analyzing data under uncertainty is a main goal for many real life problems. Statistical analysis for such data is an interested area for research. The aim of this paper is to introduce a new method concerning the generalization and modification of the rough set theory introduced early by Pawlak [Int. J. Comput. Inform. Sci. 11 (1982) 314
Straight line closure of congenital macrostomia
Directory of Open Access Journals (Sweden)
Schwarz Richard
2004-01-01
Full Text Available The results of patients operated on by Nepal Cleft Lip and Palate Association (NECLAPA surgeons for congenital macrostomia were prospectively studied between January 2000 and December 2002. There were four males and three females with a median age of 10 years. Three had an associated branchial arch syndrome. In all patients an overlapping repair of orbicularis oris was done. Six patients had a straight line closure with excellent cosmetic results and one a Z-plasty with a more obvious scar. All had a normal appearing commissure. Overlapping orbicularis repair with straight line skin closure for this rare congenital anomaly is recommended.
Surface roughness effects on heat transfer in Couette flow
International Nuclear Information System (INIS)
Elia, G.G.
1981-01-01
A cell theory for viscous flow with rough surfaces is applied to two basic illustrative heat transfer problems which occur in Couette flow. Couette flow between one adiabatic surface and one isothermal surface exhibits roughness effects on the adiabatic wall temperature. Two types of rough cell adiabatic surfaces are studied: (1) perfectly insulating (the temperature gradient vanishes at the boundary of each cell); (2) average insulating (each cell may gain or lose heat but the total heat flow at the wall is zero). The results for the roughness on a surface in motion are postulated to occur because of fluid entrainment in the asperities on the moving surface. The symmetry of the roughness effects on thermal-viscous dissipation is discussed in detail. Explicit effects of the roughness on each surface, including combinations of roughness values, are presented to enable the case where the two surfaces may be from different materials to be studied. The fluid bulk temperature rise is also calculated for Couette flow with two ideal adiabatic surfaces. The effect of roughness on thermal-viscous dissipation concurs with the viscous hydrodynamic effect. The results are illustrated by an application to lubrication. (Auth.)
DEFF Research Database (Denmark)
Bollerslev, Tim; Li, Sophia Zhengzi; Todorov, Viktor
-section. An investment strategy that goes long stocks with high jump betas and short stocks with low jump betas produces significant average excess returns. These higher risk premiums for the discontinuous and overnight market betas remain significant after controlling for a long list of other firm characteristics......Motivated by the implications from a stylized equilibrium pricing framework, we investigate empirically how individual equity prices respond to continuous, or \\smooth," and jumpy, or \\rough," market price moves, and how these different market price risks, or betas, are priced in the cross......-section of expected returns. Based on a novel highfrequency dataset of almost one-thousand individual stocks over two decades, we find that the two rough betas associated with intraday discontinuous and overnight returns entail significant risk premiums, while the intraday continuous beta is not priced in the cross...
An intersection graph of straight lines
DEFF Research Database (Denmark)
Thomassen, Carsten
2002-01-01
G. Ehrlich, S. Even, and R.E. Tarjan conjectured that the graph obtained from a complete 3 partite graph K4,4,4 by deleting the edges of four disjoint triangles is not the intersection graph of straight line segments in the plane. We show that it is....
Surface roughness influences on the behaviour of flow inside microchannels
Farias, M. H.; Castro, C. S.; Garcia, D. A.; Henrique, J. S.
2018-03-01
This work discusses influence of the surface roughness on the behavior of liquids flowing inside microchannels. By measuring the flow profile using the micro-PIV technique, the flow of water inside two rectangular microchannels of different wall roughness and in a circular smooth microchannel was studied. Comparisons were made among the experimental results, showing that a metrological approach concerning surface characteristics of microdevices is required to ensure reliability of the measurements for flow analyses in microfluidic processes.
Modelling dynamic roughness during floods
Paarlberg, Andries; Dohmen-Janssen, Catarine M.; Hulscher, Suzanne J.M.H.; Termes, A.P.P.
2007-01-01
In this paper, we present a dynamic roughness model to predict water levels during floods. Hysteresis effects of dune development are explicitly included. It is shown that differences between the new dynamic roughness model, and models where the roughness coefficient is calibrated, are most
FIXTURING DEVICE FOR DRILLING A STRAIGHT SHAFT
Directory of Open Access Journals (Sweden)
SUSAC, Florin
2017-05-01
Full Text Available The paper presents a fixturing device used for machining by drilling a straight shaft. The shaft was manufactured on EMCO CONCEPT TURN 55 CNC. The blank used was a bar with circular cross-section. The orientation and fixing scheme of the part and the orientation elements for fixturing device are presented as they were drawn in Autodesk Inventor and AutoCAD software.
Straight-line string with curvature
International Nuclear Information System (INIS)
Solov'ev, L.D.
1995-01-01
Classical and quantum solutions for the relativistic straight-line string with arbitrary dependence on the world surface curvature are obtained. They differ from the case of the usual Nambu-Goto interaction by the behaviour of the Regge trajectory which in general can be non-linear. A regularization of the action is considered and a comparison with relativistic point with curvature is made. 5 refs
Straight, white teeth as a social prerogative.
Khalid, Abeer; Quiñonez, Carlos
2015-06-01
A distinguishing feature of North American society is preoccupation with self-image, as seen in the ritualistic nature of bodily practices aimed at constantly improving the body. Nowhere is this more apparent than in the prevailing fixation with straight, white teeth. While there is an ever-expanding literature on the sociology of body, very little has been written on teeth in this context. Using literature from anthropology, biology, dentistry, sociology and social psychology, this study attempts to answer: (1) Why have straight, white teeth become a beauty ideal in North American society? (2) What is the basis for this ideal? (3) How is this ideal propagated? It demonstrates that dental aesthetic tendencies are biologically, culturally and socially patterned. Concepts from the works of Pierre Bourdieu and Michel Foucault are used to illustrate how straight, white teeth contribute towards reinforcing class differences and how society exercises a disciplinary power on individuals through this ideal. It is concluded that modified teeth are linked to self and identity that are rooted in social structure. Moreover, teeth demonstrate the ways in which class differences are embodied and projected as symbols of social advantage or disadvantage. Implications on professional, public health, sociological and political levels are considered. © 2015 Foundation for the Sociology of Health & Illness.
Lick, David J; Johnson, Kerri L
2016-06-01
Perceivers achieve above chance accuracy judging others' sexual orientations, but they also exhibit a notable response bias by categorizing most targets as straight rather than gay. Although a straight categorization bias is evident in many published reports, it has never been the focus of systematic inquiry. The current studies therefore document this bias and test the mechanisms that produce it. Studies 1-3 revealed the straight categorization bias cannot be explained entirely by perceivers' attempts to match categorizations to the number of gay targets in a stimulus set. Although perceivers were somewhat sensitive to base rate information, their tendency to categorize targets as straight persisted when they believed each target had a 50% chance of being gay (Study 1), received explicit information about the base rate of gay targets in a stimulus set (Study 2), and encountered stimulus sets with varying base rates of gay targets (Study 3). The remaining studies tested an alternate mechanism for the bias based upon perceivers' use of gender heuristics when judging sexual orientation. Specifically, Study 4 revealed the range of gendered cues compelling gay judgments is smaller than the range of gendered cues compelling straight judgments despite participants' acknowledgment of equal base rates for gay and straight targets. Study 5 highlighted perceptual experience as a cause of this imbalance: Exposing perceivers to hyper-gendered faces (e.g., masculine men) expanded the range of gendered cues compelling gay categorizations. Study 6 linked this observation to our initial studies by demonstrating that visual exposure to hyper-gendered faces reduced the magnitude of the straight categorization bias. Collectively, these studies provide systematic evidence of a response bias in sexual orientation categorization and offer new insights into the mechanisms that produce it. (PsycINFO Database Record (c) 2016 APA, all rights reserved).
Notions of Rough Neutrosophic Digraphs
Directory of Open Access Journals (Sweden)
Nabeela Ishfaq
2018-01-01
Full Text Available [-3]Graph theory has numerous applications in various disciplines, including computer networks, neural networks, expert systems, cluster analysis, and image capturing. Rough neutrosophic set (NS theory is a hybrid tool for handling uncertain information that exists in real life. In this research paper, we apply the concept of rough NS theory to graphs and present a new kind of graph structure, rough neutrosophic digraphs. We present certain operations, including lexicographic products, strong products, rejection and tensor products on rough neutrosophic digraphs. We investigate some of their properties. We also present an application of a rough neutrosophic digraph in decision-making.
21 CFR 82.5 - General specifications for straight colors.
2010-04-01
... 21 Food and Drugs 1 2010-04-01 2010-04-01 false General specifications for straight colors. 82.5... LISTING OF CERTIFIED PROVISIONALLY LISTED COLORS AND SPECIFICATIONS General Provisions § 82.5 General specifications for straight colors. No batch of a straight color listed in subpart B, C, or D shall be certified...
14 CFR 417.215 - Straight-up time analysis.
2010-01-01
... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Straight-up time analysis. 417.215 Section..., DEPARTMENT OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.215 Straight-up time analysis. A flight safety analysis must establish the straight-up time for a launch for use as a flight...
Straight and White: Talking with My Mouth Full
Myers, W. Benjamin
2008-01-01
By using straight and white teeth as a metaphor for a straight and White identity, the author reflects on how this identity is performed, maintained, and often problematic. Using literature about identity performance, three different voices speak to and from straight and White identity. Using irony by blending arrogance and ignorance in the voice…
7 CFR 29.6128 - Straight Stripped (X Group).
2010-01-01
... 7 Agriculture 2 2010-01-01 2010-01-01 false Straight Stripped (X Group). 29.6128 Section 29.6128... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.6128 Straight Stripped (X Group). This group consists of..., and tolerances X1 Fine Quality Straight Stripped. Heavy, ripe, firm, semielastic, normal strength and...
Implanting straight into cochlea risks the facial nerve: a Cartesian coordinate study.
Deshpande, Anita S; Wendell Todd, N
2016-12-01
To describe the straight-into-cochlea line that affords the best access for an electrode array to enter via the round window, and how this line relates to the facial nerve, the incus, and mastoid size. The straight-into-cochlea line is important to minimize the cochlear trauma and maximize the likelihood of placement into the scala tympani. High-resolution CT scans were obtained for ten craniums with the extremes of large (N = 5) and small (N = 5) mastoid pneumatization; the specimens were from a series of 41 ear normal craniums. Using FIJI, a publicly available software program, the straight-into-cochlea insertion line was determined by defining the x-y-z coordinates of the middle of the round window and a point 6.0 mm into the cochlea on its centrifugal wall. Then, from the extended straight-into-cochlea insertion line, we determined the shortest perpendicular distance to the middle of the fallopian canal, and from that "fallopian point" to the apex of the posterior process of the incus. We found good repeatability of measurements. We found the extended straight-into-cochlea insertion lines routinely close to or in the midst of the fallopian canal (50 % ≤ 1.0 mm). We found the lines 4.7-7.8 mm from the apex of the posterior process of the incus. Line positions relative to "fallopian point" and incus showed no relation to mastoid pneumatization. For the distance "fallopian point" to incus, bilateral symmetry was suggested. Using landmarks registered in an x-y-z coordinate system, straight-into-cochlea insertion via the round window puts the facial nerve at risk.
Directory of Open Access Journals (Sweden)
T Nguyen
2017-06-01
Full Text Available This paper studies the contact of general rough curved surfaces having nearly identical geometries, assuming the contact at each differential area obeys the model proposed by Greenwood and Williamson. In order to account for the most general gross geometry, principles of differential geometry of surface are applied. This method while requires more rigorous mathematical manipulations, the fact that it preserves the original surface geometries thus makes the modeling procedure much more intuitive. For subsequent use, differential geometry of axis-symmetric surface is considered instead of general surface (although this “general case” can be done as well in Chapter 3.1. The final formulas for contact area, load, and frictional torque are derived in Chapter 3.2.
International Nuclear Information System (INIS)
Swift, Diana.
1984-01-01
Canadian antinuclear groups, because of their shifting stances and fluid overlapping membership, are compared with shadows on a wall. They can be roughly classified as environmental, pacifist, concerned with energy, religious, or dedicated to nuclear responsibility. The author considers that such groups, despite their arguably unrealistic attitudes, have raised public awareness of the ethical, practical and financial aspects of power development in Canada and the world
New airfoil sections for straight bladed turbine
Boumaza, B.
1987-07-01
A theoretical investigation of aerodynamic performance for vertical axis Darrieus wind turbine with new airfoils sections is carried out. The blade section aerodynamics characteristics are determined from turbomachines cascade model. The model is also adapted to the vertical Darrieus turbine for the performance prediction of the machine. In order to choose appropriate value of zero-lift-drag coefficient in calculation, an analytical expression is introduced as function of chord-radius ratio and Reynolds numbers. New airfoils sections are proposed and analyzed for straight-bladed turbine.
New airfoil sections for straight bladed turbine
International Nuclear Information System (INIS)
Boumaza, B.
1987-07-01
A theoretical investigation of aerodynamic performance for vertical axis Darrieus wind turbine with new airfoils sections is carried out. The blade section aerodynamics characteristics are determined from turbomachines cascade model. The model is also adapted to the vertical Darrieus turbine for the performance prediction of the machine. In order to choose appropriate value of zero-lift-drag coefficient in calculation, an analytical expression is introduced as function of chord-radius ratio and Reynolds numbers. New airfoils sections are proposed and analyzed for straight-bladed turbine
Subjective Straight Ahead Orientation in Microgravity
Clement, G.; Reschke, M. F.; Wood, S. J.
2015-01-01
This joint ESA NASA study will address adaptive changes in spatial orientation related to the subjective straight ahead and the use of a vibrotactile sensory aid to reduce perceptual errors. The study will be conducted before and after long-duration expeditions to the International Space Station (ISS) to examine how spatial processing of target location is altered following exposure to microgravity. This study addresses the sensorimotor research gap to "determine the changes in sensorimotor function over the course of a mission and during recovery after landing."
Straight Vegetable Oil as a Diesel Fuel?
Energy Technology Data Exchange (ETDEWEB)
None
2014-01-01
Biodiesel, a renewable fuel produced from animal fats or vegetable oils, is popular among many vehicle owners and fleet managers seeking to reduce emissions and support U.S. energy security. Questions sometimes arise about the viability of fueling vehicles with straight vegetable oil (SVO), or waste oils from cooking and other processes, without intermediate processing. But SVO and waste oils differ from biodiesel (and conventional diesel) in some important ways and are generally not considered acceptable vehicle fuels for large-scale or long-term use.
The short straight sections for the LHC
International Nuclear Information System (INIS)
Bergot, J.B.; Coussy, E.; Dambre, P.; Ollivier, Y.; Reynet, D.; Vincent, D.; Rohmig, P.
1999-01-01
In 1995 a close collaboration between CERN, CEA and CNRS has been established for the design, proto-typing and follow-up of industrial series production of a sub-assembly of the Large Hadron Collider (LHC). In this frame, the design office of IPN's Accelerator R and D group has in charge one of these contracts concerning the 386 Short Straight Sections (SSS) and particularly: - the cryostat design; - the study of procedures and tool assembly; - the construction of two prototypes during the year 1999; - the industrialization and the production follow-up for the series SSS. This collaboration will last until the year 2004. (authors)
Roughness Effects on Fretting Fatigue
Yue, Tongyan; Abdel Wahab, Magd
2017-05-01
Fretting is a small oscillatory relative motion between two normal loaded contact surfaces. It may cause fretting fatigue, fretting wear and/or fretting corrosion damage depending on various fretting couples and working conditions. Fretting fatigue usually occurs at partial slip condition, and results in catastrophic failure at the stress levels below the fatigue limit of the material. Many parameters may affect fretting behaviour, including the applied normal load and displacement, material properties, roughness of the contact surfaces, frequency, etc. Since fretting damage is undesirable due to contacting, the effect of rough contact surfaces on fretting damage has been studied by many researchers. Experimental method on this topic is usually focusing on rough surface effects by finishing treatment and random rough surface effects in order to increase fretting fatigue life. However, most of numerical models on roughness are based on random surface. This paper reviewed both experimental and numerical methodology on the rough surface effects on fretting fatigue.
The surface roughness effect on the performance of supersonic ejectors
Brezgin, D. V.; Aronson, K. E.; Mazzelli, F.; Milazzo, A.
2017-07-01
The paper presents the numerical simulation results of the surface roughness influence on gas-dynamic processes inside flow parts of a supersonic ejector. These simulations are performed using two commercial CFD solvers (Star- CCM+ and Fluent). The results are compared to each other and verified by a full-scale experiment in terms of global flow parameters (the entrainment ratio: the ratio between secondary to primary mass flow rate - ER hereafter) and local flow parameters distribution (the static pressure distribution along the mixing chamber and diffuser walls). A detailed comparative study of the employed methods and approaches in both CFD packages is carried out in order to estimate the roughness effect on the logarithmic law velocity distribution inside the boundary layer. Influence of the surface roughness is compared with the influence of the backpressure (static pressure at the ejector outlet). It has been found out that increasing either the ejector backpressure or the surface roughness height, the shock position displaces upstream. Moreover, the numerical simulation results of an ejector with rough walls in the both CFD solvers are well quantitatively agreed with each other in terms of the mean ER and well qualitatively agree in terms of the local flow parameters distribution. It is found out that in the case of exceeding the "critical roughness height" for the given boundary conditions and ejector's geometry, the ejector switches to the "off-design" mode and its performance decreases considerably.
Modeling of surface roughness effects on Stokes flow in circular pipes
Song, Siyuan; Yang, Xiaohu; Xin, Fengxian; Lu, Tian Jian
2018-02-01
Fluid flow and pressure drop across a channel are significantly influenced by surface roughness on a channel wall. The present study investigates the effects of periodically structured surface roughness upon flow field and pressure drop in a circular pipe at low Reynolds numbers. The periodic roughness considered exhibits sinusoidal, triangular, and rectangular morphologies, with the relative roughness (i.e., ratio of the amplitude of surface roughness to hydraulic diameter of the pipe) no more than 0.2. Based upon a revised perturbation theory, a theoretical model is developed to quantify the effect of roughness on fully developed Stokes flow in the pipe. The ratio of static flow resistivity and the ratio of the Darcy friction factor between rough and smooth pipes are expressed in four-order approximate formulations, which are validated against numerical simulation results. The relative roughness and the wave number are identified as the two key parameters affecting the static flow resistivity and the Darcy friction factor.
Variations in roughness predictions (flume experiments)
Noordam, Daniëlle; Blom, Astrid; van der Klis, H.; Hulscher, Suzanne J.M.H.; Makaske, A.; Wolfert, H.P.; van Os, A.G.
2005-01-01
Data of flume experiments with bed forms are used to analyze and compare different roughness predictors. In this study, the hydraulic roughness consists of grain roughness and form roughness. We predict the grain roughness by means of the size of the sediment. The form roughness is predicted by
Analysis of accuracy in photogrammetric roughness measurements
Olkowicz, Marcin; Dąbrowski, Marcin; Pluymakers, Anne
2017-04-01
Regarding permeability, one of the most important features of shale gas reservoirs is the effective aperture of cracks opened during hydraulic fracturing, both propped and unpropped. In a propped fracture, the aperture is controlled mostly by proppant size and its embedment, and fracture surface roughness only has a minor influence. In contrast, in an unpropped fracture aperture is controlled by the fracture roughness and the wall displacement. To measure fracture surface roughness, we have used the photogrammetric method since it is time- and cost-efficient. To estimate the accuracy of this method we compare the photogrammetric measurements with reference measurements taken with a White Light Interferometer (WLI). Our photogrammetric setup is based on high resolution 50 Mpx camera combined with a focus stacking technique. The first step for photogrammetric measurements is to determine the optimal camera positions and lighting. We compare multiple scans of one sample, taken with different settings of lighting and camera positions, with the reference WLI measurement. The second step is to perform measurements of all studied fractures with the parameters that produced the best results in the first step. To compare photogrammetric and WLI measurements we regrid both data sets onto a regular 10 μm grid and determined the best fit, followed by a calculation of the difference between the measurements. The first results of the comparison show that for 90 % of measured points the absolute vertical distance between WLI and photogrammetry is less than 10 μm, while the mean absolute vertical distance is 5 μm. This proves that our setup can be used for fracture roughness measurements in shales.
Comparison of vegetation roughness descriptions
Augustijn, Dionysius C.M.; Huthoff, Freek; van Velzen, E.H.; Altinakar, M.S.; Kokpinar, M.A.; Aydin, I.; Cokgor, S.; Kirkgoz, S.
2008-01-01
Vegetation roughness is an important parameter in describing flow through river systems. Vegetation impedes the flow, which affects the stage-discharge curve and may increase flood risks. Roughness is often used as a calibration parameter in river models, however when vegetation is allowed to
Bankruptcy Prediction with Rough Sets
J.C. Bioch (Cor); V. Popova (Viara)
2001-01-01
textabstractThe bankruptcy prediction problem can be considered an or dinal classification problem. The classical theory of Rough Sets describes objects by discrete attributes, and does not take into account the order- ing of the attributes values. This paper proposes a modification of the Rough Set
Generalizing roughness: experiments with flow-oriented roughness
Trevisani, Sebastiano
2015-04-01
Surface texture analysis applied to High Resolution Digital Terrain Models (HRDTMs) improves the capability to characterize fine-scale morphology and permits the derivation of useful morphometric indexes. An important indicator to be taken into account in surface texture analysis is surface roughness, which can have a discriminant role in the detection of different geomorphic processes and factors. The evaluation of surface roughness is generally performed considering it as an isotropic surface parameter (e.g., Cavalli, 2008; Grohmann, 2011). However, surface texture has often an anisotropic character, which means that surface roughness could change according to the considered direction. In some applications, for example involving surface flow processes, the anisotropy of roughness should be taken into account (e.g., Trevisani, 2012; Smith, 2014). Accordingly, we test the application of a flow-oriented directional measure of roughness, computed considering surface gravity-driven flow. For the calculation of flow-oriented roughness we use both classical variogram-based roughness (e.g., Herzfeld,1996; Atkinson, 2000) as well as an ad-hoc developed robust modification of variogram (i.e. MAD, Trevisani, 2014). The presented approach, based on a D8 algorithm, shows the potential impact of considering directionality in the calculation of roughness indexes. The use of flow-oriented roughness could improve the definition of effective proxies of impedance to flow. Preliminary results on the integration of directional roughness operators with morphometric-based models, are promising and can be extended to more complex approaches. Atkinson, P.M., Lewis, P., 2000. Geostatistical classification for remote sensing: an introduction. Computers & Geosciences 26, 361-371. Cavalli, M. & Marchi, L. 2008, "Characterization of the surface morphology of an alpine alluvial fan using airborne LiDAR", Natural Hazards and Earth System Science, vol. 8, no. 2, pp. 323-333. Grohmann, C
Attitudes toward straight, gay male, and transsexual parenting.
Weiner, Brittany A; Zinner, Leah
2015-01-01
This study examined American attitudes toward transsexual and gay male parenting, compared to straight parenting. After reporting levels of transphobia, participants read a vignette regarding a couple seeking child adoption. Individuals high in transphobia perceived nontraditional couples as more emotionally unstable than straight couples and were less willing to grant custody of a child to the nontraditional couples vs. the straight couples. In addition, the transsexual couple faced more prejudice and discrimination than the gay male couple. Implications of these findings are discussed.
Free-boundary stability of straight stellarators
International Nuclear Information System (INIS)
Barnes, D.C.; Cary, J.R.
1984-02-01
The sharp-boundary model is used to investigate the stability of straight stellarators to free-boundary, long-wavelength modes. To correctly analyze the heliac configuration, previous theory is generalized to the case of arbitrary helical aspect ratio (ratio of plasma radius to periodicity lengths). A simple low-β criterion involving the vacuum field and the normalized axial current is derived and used to investigate a large variety of configurations. The predictions of this low-β theory are verified by numerical minimization of deltaW at arbitrary β. The heliac configuration is found to be remarkably stable, with a critical β of over 15% determined by the lack of equilibrium rather than the onset of instability. In addition, other previously studied systems are found to be stabilized by net axial plasma current
A straightness error measurement method matched new generation GPS
International Nuclear Information System (INIS)
Zhang, X B; Lu, H; Jiang, X Q; Li, Z
2005-01-01
The axis of the non-diffracting beam produced by an axicon is very stable and can be adopted as the datum line to measure the spatial straightness error in continuous working distance, which may be short, medium or long. Though combining the non-diffracting beam datum-line with LVDT displace detector, a new straightness error measurement method is developed. Because the non-diffracting beam datum-line amends the straightness error gauged by LVDT, the straightness error is reliable and this method is matchs new generation GPS
Friction factor in smooth and rough gas pipelines. An experimental study
Energy Technology Data Exchange (ETDEWEB)
Sletfjerding, Elling
1999-01-01
Flow of high pressure natural gas in pipelines has been studied experimentally. Pipeline flow of natural gas is characterized by high Reynolds numbers due to the low viscosity and relatively high density of pressurized gas. Friction factor correlations for high Reynolds number flow in smooth and rough pipes were developed. To study the effect of wall roughness on pipe flow at high Reynolds numbers 8 test pipes with different wall roughness were fabricated. The wall roughness in 6 of the test pipes was varied by adding glass beads in an epoxy coating applied on the pipe wall. One test pipe was treated with a smooth epoxy coating and one was left untreated. The inner diameter of the test pipes was 150 mm. Measurements of the pressure drop in the pipes were made in a closed flow loop at line pressures of 25, 70, 95 and 120 bar. The Reynolds number of the flow was varied in the range 2-30 million. The wall roughness of the test pipes was measured with a stylus instrument. Correlations between the directly measured wall roughness and the friction factor at fully rough flow conditions were presented. To characterize the wall roughness of the test pipes a parameter combining a measure of the roughness height (R{sub q}) and the texture of the wall roughness was used. Due to the high Reynolds number of the flow, minute irregularities of the pipe wall had significant effect on the friction factor in the pipe. The measured wall roughness of the test pipes was in the range 1.4 < R{sub q} <31 (my)m. The flow experiments in test pipes was compared with data from operating pipelines in the North Sea. The offshore pipelines are coated with the same epoxy coating as used in the test pipes. The friction factor in coated offshore gas pipelines showed smooth behavior when the additional pressure drop due to welds were accounted for. The study of coated gas pipelines showed that the friction factor was significantly lower than predicted by standard correlations.
Marfisi, Karem; Mercadé, Montserrat; Plotino, Gianluca; Clavel, Tatiana; Duran-Sindreu, Fernando; Roig, Miguel
2015-01-01
To compare the efficacy of Reciproc(®) (VDW GmbH) and ProFile(®) (Dentsply Maillefer) instruments at removing gutta-percha from straight and curved root canals ex vivo filled using the cold lateral condensation and GuttaMaster(®) (VDW GmbH) techniques. Forty mesial roots of mandibular molars with two curved canals and 80 single-rooted teeth with straight root canals, a total of 160 root canals, were randomly assigned to eight groups (canals per group = 20) according to filling technique, retreatment instrument and root canal curvature as follows: Group I, cold lateral condensation/ProFile(®)/straight; Group II, cold lateral condensation/ProFile(®)/curved; Group III, cold lateral condensation/Reciproc(®)/straight; Group IV, cold lateral condensation/Reciproc(®)/curved; Group V, GuttaMaster(®)/ProFile(®)/straight; Group VI, GuttaMaster(®)/ProFile(®)/curved; Group VII, GuttaMaster(®)/Reciproc(®)/straight; and Group VIII, GuttaMaster(®)/Reciproc(®)/curved. The following data were recorded: procedural errors, retreatment duration and canal wall cleanliness. Means and standard deviations were calculated and analysed using the Kruskal-Wallis test, one-way analysis of variance and Tukey's test (P straight (P = 0.0001) and curved (P = 0.0003) root canals. Reciproc(®) were statistically more effective than ProFile(®) instruments in removing GuttaMaster(®) from straight root canals (P = 0.021). Regardless of filling technique or retreatment instrument, gutta-percha was removed more rapidly from curved than from straight root canals (P = 0.0001). Neither system completely removed filling material from the root canals. Compared with ProFile(®) instruments, Reciproc(®) instruments removed GuttaMaster(®) filling material from straight and curved root canals more rapidly.
Influence of a k-type Roughness on the Behaviour of Turbulence in an Unsteady Channel Flow
International Nuclear Information System (INIS)
Seddighi, Mehdi; He Shuisheng; Vardy, Alan E; Orlandi, Paolo
2011-01-01
Direct Numerical Simulations (DNS) have been carried out for a spatially fully developed turbulent channel flow with one smooth wall and one k-type rough-wall surface to study the influence of a square bar roughness on the behaviour of unsteady turbulent flow. The flow state under investigation is a uniform acceleration from an initially steady turbulent flow. Results are compared with simulations of flows in a smooth wall channel undergoing a similar acceleration, and with quasi-steady behaviour obtained using steady flow simulations. The turbulence in the wall region and the buffer layer of an accelerating flow with a rough wall shows strikingly different behaviour from that of corresponding flows with smooth walls. The characteristic long delays in the response of the streamwise turbulent velocity and the different behaviours of the three turbulent velocity components that are exhibited in smooth wall flows are not seen in the rough wall flow. This is attributed to different turbulent production mechanisms in the two types of flows. Important differences are also seen in the wall shear stress responses one wall is rough and when both walls are smooth.
Armor Plate Surface Roughness Measurements
National Research Council Canada - National Science Library
Stanton, Brian; Coburn, William; Pizzillo, Thomas J
2005-01-01
...., surface texture and coatings) that could become important at high frequency. We measure waviness and roughness of various plates to know the parameter range for smooth aluminum and rolled homogenous armor (RHA...
International Nuclear Information System (INIS)
Shultis, J.K.; Thompson, K.R.; Faw, R.E.
1986-01-01
Approximate computational models are developed to describe the spatial variation in the radiation field transmitted through a straight reactangular duct obliquely illuminated by monoenergetic gamma photons. These models account for single and multiple scattering from the duct walls and lips as well as for direct penetration by the photons. Results of calculations are compared to results from a recent benchmark duct streaming experiment, and empirical correction factors are obtained which enable the models to predict the transmitted exposure rates to within 20% of the experimental values
Thermal neutrons streaming in straight duct
International Nuclear Information System (INIS)
Jehouani, A.; Boulkheir, M.; Ichaoui, R.
2000-01-01
The neutron streaming in duct is due to two phenomena: a) direct propagation and b) reflection on duct wall. We have used the Monte Carlo method to evaluate the ratio of the reflected neutrons flux by the duct wall to the total flux at the exit of the duct for iron and aluminium. Ten neutrons energy groups are considered between 10 -5 eV and 10 eV. A Fortran program is developed to evaluate the neutron double differential albedo. It is shown that the two following approximations are largely justified: i) Three collisions in the duct wall are sufficient to attain the asymptotic limit of the multiscattered neutron double differential albedo ii) The points of entry and exit of the neutron in the duct wall may be considered the same for the multiscattered neutrons. For a punctual source at the mouth of the duct, we have determined the direct and the reflected part of the total thermal neutron flux at the exit of the duct for different lengths and different radius of the duct. For a punctual source, we have found that the major contribution to the total flux of neutrons at the exit is due to the neutron reflection by walls and the reflection contribution decreases when the neutron energy decreases. For a constant length of the duct, the reflected part decreases when the duct radius increases while for the disk shaped source we have found the opposite phenomena. The transmitted neutron flux distribution at the exit of the duct are determined for disk shaped source for different neutron energy and for different distance from the exit center. (author)
Stigma and Stigma by Association in Perceptions of Straight Allies
Goldstein, Susan B.
2017-01-01
As evidence builds for straight allies' contributions to battling sexual prejudice, barriers to assuming this role must be identified and dismantled. This study investigated stigma and stigma by association in perceptions of straight allies in a college population. Adjective rating items were completed by 505 participants who identified as…
Setting the Record Straight. The Truth About Fad Diets.
Wheat Foods Council, Parker, CO.
The Setting the Record Straight information packet presents facts to set the record straight about nutrition and debunk fad diets. The kit features materials designed to communicate the importance of balanced eating. Materials include: a time line of fad diets; four reproducible fad diet book review handouts that show the misleading claims rampant…
Spider diffraction: a comparison of curved and straight legs
International Nuclear Information System (INIS)
Richter, J.L.
1984-01-01
It has been known for some time that, if curved legs rather than the usual straight ones are used in the spider that supports the secondary optics in certain telescopes, the visible diffraction effect is reduced. Fraunhofer theory is used to calculate the diffraction effects due to the curved leg spider. Calculated and photographic diffraction patterns are compared for straight and curved leg spiders
Mirsalehi, Marjan; Rau, Thomas S; Harbach, Lenka; Hügl, Silke; Mohebbi, Saleh; Lenarz, Thomas; Majdani, Omid
2017-05-01
The aim of the study was to evaluate insertion forces during manual insertion of a straight atraumatic electrode in human temporal bones, and post-implantation histologic evaluation of the samples to determine whether violation of intracochlear structures is related to insertion forces. In order to minimize intracochlear trauma and preserve residual hearing during cochlear implantation, knowledge of the insertion forces is necessary. Ten fresh frozen human temporal bones were prepared with canal wall down mastoidectomy. All samples were mounted on a one-axis force sensor. Insertion of a 16-mm straight atraumatic electrode was performed from different angles to induce "traumatic" insertion. Histologic evaluation was performed in order to evaluate intracochlear trauma. In 4 of 10 samples, dislocation of the electrode into scala vestibuli was observed. The mean insertion force for all 10 procedures was 0.003 ± 0.005 N. Insertion forces measured around the site of dislocation to scala vestibuli in 3 of 4 samples were significantly higher than insertion forces at the same location of the cochleae measured in samples without trauma (p straight atraumatic electrode is lower than reported by other studies using longer electrodes. Based on our study, insertion forces leading to basilar membrane trauma may be lower than the previously reported direct rupture forces.
Sudjai, W.; Juntasaro, V.; Juttijudata, V.
2018-01-01
The accuracy of predicting turbulence induced secondary flows is crucially important in many industrial applications such as turbine blade internal cooling passages in a gas turbine and fuel rod bundles in a nuclear reactor. A straight square duct is popularly used to reveal the characteristic of turbulence induced secondary flows which consists of two counter rotating vortices distributed in each corner of the duct. For a rotating duct, the flow can be divided into the pressure side and the suction side. The turbulence induced secondary flows are converted to the Coriolis force driven two large circulations with a pair of additional vortices on the pressure wall due to the rotational effect. In this paper, the Large Eddy Simulation (LES) of turbulence induced secondary flows in a straight square duct is performed using the ANSYS FLUENT CFD software. A dynamic kinetic energy subgrid-scale model is used to describe the three-dimensional incompressible turbulent flows in the stationary and the rotating straight square ducts. The Reynolds number based on the friction velocity and the hydraulic diameter is 300 with the various rotation numbers for the rotating cases. The flow is assumed fully developed by imposing the constant pressure gradient in the streamwise direction. For the rotating cases, the rotational axis is placed perpendicular to the streamwise direction. The simulation results on the secondary flows and the turbulent statistics are found to be in good agreement with the available Direct Numerical Simulation (DNS) data. Finally, the details of the Coriolis effects are discussed.
Scintillation investigation of the straight back syndrome
International Nuclear Information System (INIS)
Ebaid, M.; Serro Azul, L.G.; Kedor, H-H.; Papaleo Netto, M.; Mignone, C.A.; Carvalho, N. de
1976-01-01
Scintigraphic study of the lungs was undertaken in 17 patients with the straight back syndrome divided in three groups: I. mild form; II. moderate form and III. severe form. The results showed that: a) there is a decreased flow through the pulmonary arteries; b) bilateral morphological alterations are most common (64.6%); c) the compression of the chest cause an increased cardiac silhouette in groups II (22.2%) and III (50%) besides widening of the mediastinum in all groups (25%, 44.4% and 75%, respectively); d. functional restriction is moderate in 61.5% and severe in 38.4% of the patients in the first two groups; in group III, moderate restriction is observed in 75% of the patients and severe restriction in 25%. Results indicate that the alterations observed in the scintigraphic study of the strainght back syndrome are caused by the effects of the deformed chest on the arterial perfusion of the lung. However, the severity of the anomaly and the decrease in the pulmonary circulation could not be correlated statistically [pt
Complex Effects of Free Stream Turbulence and Surface Roughness on the Transitional Intermittency
Czech Academy of Sciences Publication Activity Database
Hladík, Ondřej; Jonáš, Pavel; Mazur, Oton; Uruba, Václav
2012-01-01
Roč. 14, 4a (2012), s. 47-52 ISSN 1335-4205 R&D Projects: GA ČR GAP101/12/1271 Institutional research plan: CEZ:AV0Z20760514 Keywords : by-pass transition * rough wall boundary layer * CTA anemometry * instantaneous wall friction * intermittency analysis Subject RIV: BK - Fluid Dynamics
Verberne, Juul; Risi, Frank; Campbell, Luke; Chambers, Scott; O'Leary, Stephen
2017-01-01
Scala tympani morphology influences the insertion dynamics and intra-scalar position of straight electrode arrays. Hearing preservation is the goal of cochlear implantation with current thin straight electrode arrays. These hug the lateral wall, facilitating full, atraumatic insertions. However, most studies still report some postoperative hearing loss. This study explores the influence of scala tympani morphology on array position relative to the basilar membrane and its possible contribution to postoperative hearing loss. Twenty-six fresh-frozen human temporal bones implanted with a straight electrode array were three-dimensionally reconstructed from micro-photographic histological sections. Insertion depth and the proximity between the array and basilar membrane were recorded. Lateral wall shape was quantified as a curvature ratio. Insertion depths ranged from 233 to 470 degrees. The mean first point of contact between the array and basilar membrane was 185 degrees; arrays tended to remain in contact with the membrane after first contacting it. Eighty-nine and 93% of arrays that reached the upper basal (>240-360 degrees) and second (>360-720 degrees) turns respectively contacted the basilar membrane in these regions. Scalar wall curvature ratio decreased significantly (the wall became steeper) from the basal to second turns. This shift correlated with a reduced distance between the array and basilar membrane. Scala tympani morphology influences the insertion dynamics and intra-scalar position of a straight electrode array. In addition to gross trauma of cochlear structures, contact between the array and basilar membrane and how this impacts membrane function should be considered in hearing preservation cases.
Analysis of turbulent heat and momentum transfer in a transitionally rough turbulent boundary layer
Doosttalab, Ali; Dharmarathne, Suranga; Tutkun, Murat; Adrian, Ronald; Castillo, Luciano
2016-11-01
A zero-pressure-gradient (ZPG) turbulent boundary layer over a transitionally rough surface is studied using direct numerical simulation (DNS). The rough surface is modeled as 24-grit sandpaper which corresponds to k+ 11 , where k+ is roughness height. Reynolds number based on momentum thickness is approximately 2400. The walls are isothermal and turbulent flow Prandtl number is 0.71. We simulate temperature as passive scalar. We compute the inner product of net turbulent force (d (u1ui) / dxi) and net turbulent heat flux (d (ui θ / dxi)) in order to investigate (i) the correlation between these vectorial quantities, (II) size of the projection of these fields on each other and (IIi) alignment of momentum and hear flux. The inner product in rough case results in larger projection and better alignment. In addition, our study on the vortices shows that surface roughness promotes production of vortical structures which affects the thermal transport near the wall.
Geometrical properties of rough metallic surfaces and their implication in electromagnetic problems
International Nuclear Information System (INIS)
Hernandez, A.; Chicon, R.; Ortuno, M.; Abellan, J.
1987-01-01
We analyze the geometrical properties and their implications in the effective surface resistance and wall losses of rough metallic surfaces. The power spectrum and the autocorrelation function are calculated for a simple model that adequately represent the rough surface. The roughness parameters are obtained through average values of the roughness and its derivative. We calculate the density profile, directly related to the depth-dependent effective conductivity. The data from the profilometer are corrected to take into account the finite size of the tip. (author)
Characteristics of wall pressure over wall with permeable coating
Energy Technology Data Exchange (ETDEWEB)
Song, Woo Seog; Shin, Seungyeol; Lee, Seungbae [Inha Univ., Incheon (Korea, Republic of)
2012-11-15
Fluctuating wall pressures were measured using an array of 16 piezoelectric transducers beneath a turbulent boundary layer. The coating used in this experiment was an open cell, urethane type foam with a porosity of approximately 50 ppi. The ultimate objective of the coating is to provide a mechanical filter to reduce the wall pressure fluctuations. The ultimate objective of the coating is to provide a mechanical filter to reduce the wall pressure fluctuations. The boundary layer on the flat plate was measured by using a hot wire probe, and the CPM method was used to determine the skin friction coefficient. The wall pressure autospectra and streamwise wavenumber frequency spectra were compared to assess the attenuation of the wall pressure field by the coating. The coating is shown to attenuate the convective wall pressure energy. However, the relatively rough surface of the coating in this investigation resulted in a higher mean wall shear stress, thicker boundary layer, and higher low frequency wall pressure spectral levels compared to a smooth wall.
Paired Straight Hearth Furnace - Transformational Ironmaking Process
Energy Technology Data Exchange (ETDEWEB)
Lu, Wei-Kao [McMaster Univ., Hamilton, ON (Canada); Debski, Paul [Andritz Metals Inc.,Canonsburg, PA (United States)
2014-11-19
The U. S. steel industry has reduced its energy intensity per ton of steel shipped by 33% since 1990. However, further significant gains in energy efficiency will require the development of new, transformational iron and steelmaking processes. The Paired Straight Hearth Furnace (PSH) process is an emerging alternative high productivity, direct reduced iron (DRI) technology that may achieve very low fuel rates and has the potential to replace blast furnace ironmaking. The PSH furnace can operate independently or may be coupled with other melting technologies to produce liquid hot metal that is both similar to blast furnace iron and suitable as a feedstock for basic oxygen steelmaking furnaces. The PSH process uses non-metallurgical coal as a reductant to convert iron oxides such as iron ore and steelmaking by-product oxides to DRI pellets. In this process, a multi-layer, nominally 120mm tall bed of composite “green balls” made from oxide, coal and binder is built up and contained within a moving refractory hearth. The pellet bed absorbs radiant heat energy during exposure to the high temperature interior refractory surfaces of the PSH while generating a strongly reducing gas atmosphere in the bed that yields a highly metalized DRI product. The PSH concept has been well tested in static hearth experiments. A moving bed design is being developed. The process developers believe that if successful, the PSH process has the potential to replace blast furnaces and coke ovens at a fraction of the operating and capital cost while using about 30% less energy relative to current blast furnace technology. DRI output could also feed electric arc furnaces (EAFs) by displacing a portion of the scrap charge.
Yang, Mei
2016-01-01
Cooling heat transfer of supercritical CO2 in horizontal straight tubes with wall is numerically investigated by using FLUENT. The results show that almost all models are able to present the trend of heat transfer qualitatively, and the stand k−ε with enhanced wall treatment model shows the best agreement with the experimental data, followed by LB low Re turbulence model. Then further studies are discussed on velocity, temperature and turbulence distributions. The parameters which are defined as the criterion of buoyancy effect on convection heat transfer are introduced to judge the condition of the fluid. The relationships among the inlet temperature, outlet temperature, the mass flow rate, the heat flux and the diameter are discussed and the difference between the cooling and heating of CO2 are compared. PMID:27458729
Directory of Open Access Journals (Sweden)
Mei Yang
Full Text Available Cooling heat transfer of supercritical CO2 in horizontal straight tubes with wall is numerically investigated by using FLUENT. The results show that almost all models are able to present the trend of heat transfer qualitatively, and the stand k-ε with enhanced wall treatment model shows the best agreement with the experimental data, followed by LB low Re turbulence model. Then further studies are discussed on velocity, temperature and turbulence distributions. The parameters which are defined as the criterion of buoyancy effect on convection heat transfer are introduced to judge the condition of the fluid. The relationships among the inlet temperature, outlet temperature, the mass flow rate, the heat flux and the diameter are discussed and the difference between the cooling and heating of CO2 are compared.
Dynamical structure of the turbulent boundary layer on rough surface
Czech Academy of Sciences Publication Activity Database
Uruba, Václav; Jonáš, Pavel; Hladík, Ondřej
2011-01-01
Roč. 11, č. 1 (2011), s. 603-604 ISSN 1617-7061 R&D Projects: GA ČR GA101/08/1112; GA ČR GAP101/10/1230 Institutional research plan: CEZ:AV0Z20760514 Keywords : turbulent boundary layer * rough wall * hairpin vortex Subject RIV: BK - Fluid Dynamics http://onlinelibrary.wiley.com/doi/10.1002/pamm.201110291/abstract
Stochastic control with rough paths
International Nuclear Information System (INIS)
Diehl, Joscha; Friz, Peter K.; Gassiat, Paul
2017-01-01
We study a class of controlled differential equations driven by rough paths (or rough path realizations of Brownian motion) in the sense of Lyons. It is shown that the value function satisfies a HJB type equation; we also establish a form of the Pontryagin maximum principle. Deterministic problems of this type arise in the duality theory for controlled diffusion processes and typically involve anticipating stochastic analysis. We make the link to old work of Davis and Burstein (Stoch Stoch Rep 40:203–256, 1992) and then prove a continuous-time generalization of Roger’s duality formula [SIAM J Control Optim 46:1116–1132, 2007]. The generic case of controlled volatility is seen to give trivial duality bounds, and explains the focus in Burstein–Davis’ (and this) work on controlled drift. Our study of controlled rough differential equations also relates to work of Mazliak and Nourdin (Stoch Dyn 08:23, 2008).
Heat transfer from rough surfaces
International Nuclear Information System (INIS)
Dalle Donne, M.
1977-01-01
Artificial roughness is often used in nuclear reactors to improve the thermal performance of the fuel elements. Although these are made up of clusters of rods, the experiments to measure the heat transfer and friction coefficients of roughness are performed with single rods contained in smooth tubes. This work illustrated a new transformation method to obtain data applicable to reactor fuel elements from these annulus experiments. New experimental friction data are presented for ten rods, each with a different artificial roughness made up of two-dimensional rectangular ribs. For each rod four tests have been performed, each in a different outer smooth tube. For two of these rods, each for two different outer tubes, heat transfer data are also given. The friction and heat transfer data, transformed with the present method, are correlated by simple equations. In the paper, these equations are applied to a case typical for a Gas Cooled Fast Reactor fuel element. (orig.) [de
Stochastic control with rough paths
Energy Technology Data Exchange (ETDEWEB)
Diehl, Joscha [University of California San Diego (United States); Friz, Peter K., E-mail: friz@math.tu-berlin.de [TU & WIAS Berlin (Germany); Gassiat, Paul [CEREMADE, Université Paris-Dauphine, PSL Research University (France)
2017-04-15
We study a class of controlled differential equations driven by rough paths (or rough path realizations of Brownian motion) in the sense of Lyons. It is shown that the value function satisfies a HJB type equation; we also establish a form of the Pontryagin maximum principle. Deterministic problems of this type arise in the duality theory for controlled diffusion processes and typically involve anticipating stochastic analysis. We make the link to old work of Davis and Burstein (Stoch Stoch Rep 40:203–256, 1992) and then prove a continuous-time generalization of Roger’s duality formula [SIAM J Control Optim 46:1116–1132, 2007]. The generic case of controlled volatility is seen to give trivial duality bounds, and explains the focus in Burstein–Davis’ (and this) work on controlled drift. Our study of controlled rough differential equations also relates to work of Mazliak and Nourdin (Stoch Dyn 08:23, 2008).
Information Measures of Roughness of Knowledge and Rough Sets for Incomplete Information Systems
Institute of Scientific and Technical Information of China (English)
LIANG Ji-ye; QU Kai-she
2001-01-01
In this paper we address information measures of roughness of knowledge and rough sets for incomplete information systems. The definition of rough entropy of knowledge and its important properties are given. In particular, the relationship between rough entropy of knowledge and the Hartley measure of uncertainty is established. We show that rough entropy of knowledge decreases monotonously as granularity of information become smaller. This gives an information interpretation for roughness of knowledge. Based on rough entropy of knowledge and roughness of rough set. a definition of rough entropy of rough set is proposed, and we show that rough entropy of rough set decreases monotonously as granularity of information become smaller. This gives more accurate measure for roughness of rough set.
Conceptual Design of ILC Damping Ring Wiggler Straight Vacuum System
International Nuclear Information System (INIS)
Marks, S.; Kennedy, K.; Plate, D.; Schlueter, R.D.; Zisman, M.
2007-01-01
The positron and electron damping rings for the International Linear Collider will contain long straight sections consisting of twenty wiggler/quadrupole pairs. The wigglers will be based upon the CESR superconducting design. There are a number of challenges associated with the design of the wiggler straight vacuum system, in particular, the absorption of photon power generated by the wigglers. This paper will present the overall conceptual design of the wiggler straight vacuum system developed for the ILC Reference Design Report. Particular emphasis will be placed on photon power load calculations and the absorber design
Northeast fish. Something like tracing straight lines.
Directory of Open Access Journals (Sweden)
Christian Florian
2009-06-01
Full Text Available This article/interview with Marzio Perin (Permasteelisa Group investigates the cause-effect relations between the adoption of cutting-edge digital tools and the positive achievements in design, project management and construction of architectural envelopes complex geometries. It is the case, for example, of the Gehry Partners Barcelona Olympic Fish, first “digital project” of the american firm and first of several collaborations with the Permasteelisa group, world leader in Curtain wall projects. The article discusses the various aspects of the construction of a complex envelope: from design coordination, to production, installation and maintenance.
Straight Talk for Good Health | NIH MedlinePlus the Magazine
... of this page please turn Javascript on. Feature: Straight Talk for Good Health Straight Talk for Good Health Past Issues / Spring 2013 ... with your Doctor nihseniorhealth.gov/talkingwithyourdoctor/toc.html Straight talk with your healthcare provider is important. You ...
Does Surface Roughness Amplify Wetting?
Czech Academy of Sciences Publication Activity Database
Malijevský, Alexandr
2014-01-01
Roč. 141, č. 18 (2014), s. 184703 ISSN 0021-9606 R&D Projects: GA ČR GA13-09914S Institutional support: RVO:67985858 Keywords : density functional theory * wetting * roughness Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.952, year: 2014
Calibration of surface roughness standards
DEFF Research Database (Denmark)
Thalmann, R.; Nicolet, A.; Meli, F.
2016-01-01
organisations. Five surface texture standards of different type were circulated and on each of the standards several roughness parameters according to the standard ISO 4287 had to be determined. 32 out of 395 individual results were not consistent with the reference value. After some corrective actions...
Fuzzy Rough Ring and Its Prop erties
Institute of Scientific and Technical Information of China (English)
REN Bi-jun; FU Yan-ling
2013-01-01
This paper is devoted to the theories of fuzzy rough ring and its properties. The fuzzy approximation space generated by fuzzy ideals and the fuzzy rough approximation operators were proposed in the frame of fuzzy rough set model. The basic properties of fuzzy rough approximation operators were analyzed and the consistency between approximation operators and the binary operation of ring was discussed.
Human roughness perception and possible factors effecting roughness sensation.
Aktar, Tugba; Chen, Jianshe; Ettelaie, Rammile; Holmes, Melvin; Henson, Brian
2017-06-01
Surface texture sensation is significant for business success, in particular for solid surfaces for most of the materials; including foods. Mechanisms of roughness perception are still unknown, especially under different conditions such as lubricants with varying viscosities, different temperatures, or under different force loads during the observation of the surface. This work aims to determine the effect of those unknown factors, with applied sensory tests on 62 healthy participants. Roughness sensation of fingertip was tested under different lubricants including water and diluted syrup solutions at room temperature (25C) and body temperature (37C) by using simple pair-wise comparison to observe the just noticeable difference threshold and perception levels. Additionally, in this research applied force load during roughness observation was tested with pair-wise ranking method to illustrate its possible effect on human sensation. Obtained results showed that human's capability of roughness discrimination reduces with increased viscosity of the lubricant, where the influence of the temperature was not found to be significant. Moreover, the increase in the applied force load showed an increase in the sensitivity of roughness discrimination. Observed effects of the applied factors were also used for estimating the oral sensation of texture during eating. These findings are significant for our fundamental understanding to texture perception, and for the development of new food products with controlled textural features. Texture discrimination ability, more specifically roughness discrimination capability, is a significant factor for preference and appreciation for a wide range of materials, including food, furniture, or fabric. To explore the mechanism of sensation capability through tactile senses, it is necessary to identify the relevant factors and define characteristics that dominate the process involved. The results that will be obtained under these principles
Equilibrium depth of scour at straight guide banks
Gjunsburgs, B.; Bulankina, V.
2017-10-01
The equilibrium stage of scour at the head of straight guide banks with a uniform and stratified bed conditions have been studied. The contraction of the river by bridge crossing with straight guide banks considerably alters the flow pattern. The streamlines become curve and the concentration of streamlines, longitudinal and transverse slopes of the water surface, a local increase in velocity, vortex and eddy structures, and the origin of a flow separation zone between the extreme streamlines and the guide bank are observed and local scour is developing at the head of the straight guide banks. New formulae for calculation of equilibrium depth of scour at straight guide banks at uniform and stratified river bed is elaborated and confirmed by tests and computer modelling results.
Highly sensitive straightness measurement system using a ball-lens
International Nuclear Information System (INIS)
Lee, Minho; Yang, Hyun-Ik; Cho, Nahm-Gyoo
2016-01-01
In this paper, a new and simple optical technique to accurately measure the straightness errors of a linear stage is proposed. To improve the performance, including the measurement sensitivity and resolution of the measurement system, and to simultaneously measure two-dimensional straightness errors (2D straightness errors), an optical system was designed using a laser, a retro-reflector, a ball-lens, and a two-dimensional position sensitive detector (2D PSD). The characteristics of the measurement system were analytically and experimentally investigated. A prototype measurement system was manufactured based on the investigated results, and the performances of this system have been tested. The measuring performance of the system was easily improved by about 12 times using the proposed technique and it can be further improved. It is shown that the proposed technique can easily and effectively improve the performance of a conventional straightness measurement system based on the geometric optical method using a PSD. (paper)
Straight studs from southern pine veneer cores and cordwood
Peter Koch
1968-01-01
An economically feasible system has been developed for converting southern pine veneer cores into straight 8-foot studs (2). Prototype studs - two per core - were 100 percent SPIB stud grade and better.
Uncertainty of spatial straightness in 3D measurement
International Nuclear Information System (INIS)
Wang Jinxing; Jiang Xiangqian; Ma Limin; Xu Zhengao; Li Zhu
2005-01-01
The least-square method is commonly employed to verify the spatial straightness in actual three-dimensional measurement process, but the uncertainty of the verification result is usually not given by the coordinate measuring machines. According to the basic principle of spatial straightness least-square verification and the uncertainty propagation formula given by ISO/TS 14253-2, a calculation method for the uncertainty of spatial straightness least-square verification is proposed in this paper. By this method, the coefficients of the line equation are regarded as a statistical vector, so that the line equation, the result of the spatial straightness verification and the uncertainty of the result can be obtained after the expected value and covariance matrix of the vector are determined. The method not only assures the integrity of the verification result, but also accords with the requirement of the new generation of GPS standards, which can improve the veracity of verification
Qingping Straight Sword: The Last Remaining Chinese Sword System?
Directory of Open Access Journals (Sweden)
Stephan Berwick
2012-07-01
Full Text Available The following examination of classical Chinese straight sword (jian details the very rare Qingping straight sword system. The study meshes Chinese- and English-sourced research with a revealing interview (conducted by America’s senior Qingping disciples, Reza Momenan and Hon Lee with Lu Junhai—the grandmaster of this unique sword system. The author presents Qingping system as perhaps the only known, complete Chinese sword system surviving from China’s pre-Rebulican era (1911-1949.
Exact equivalent straight waveguide model for bent and twisted waveguides
DEFF Research Database (Denmark)
Shyroki, Dzmitry
2008-01-01
Exact equivalent straight waveguide representation is given for a waveguide of arbitrary curvature and torsion. No assumptions regarding refractive index contrast, isotropy of materials, or particular morphology in the waveguide cross section are made. This enables rigorous full-vector modeling...... of in-plane curved or helically wound waveguides with use of available simulators for straight waveguides without the restrictions of the known approximate equivalent-index formulas....
Straight leg elevation to rule out pelvic injury.
Bolt, Caroline; O'Keeffe, Francis; Finnegan, Pete; Dickson, Kristofer; Smit, De Villiers; Fitzgerald, Mark C; Mitra, Biswadev
2018-02-01
Pelvic x-ray is frequently used as a screening tool during initial assessment of injured patients. However routine use in the awake and alert blunt trauma patient may be questioned due to low yield. We propose a clinical tool that may avoid unnecessary imaging by examining whether the ability to straight leg raise, without pain, can rule out pelvic injury. We conducted a prospective cohort study with the exposure variables of ability to straight leg raise and presence of pain on doing so, and presence of pelvic fracture on x-ray as the primary outcome variable. Of the 328 participants, 35 had pelvic fractures, and of these 32 were either unable to straight leg raise, or had pain on doing so, with a sensitivity of 91.43% (95% CI: 76.94-98.2%) and a negative predictive value of 98.57% (95% CI: 95.88-99.70%). The 3 participants with a pelvic fracture who could straight leg raise with no pain, all had a GCS of less than 15, and therefore, among the sub-group of patients with GCS15, a 100% sensitivity and 100% negative predictive value for straight leg raise with no pain to rule out pelvic fracture was demonstrated. Among awake, alert patients, painless straight leg raise can exclude pelvic fractures and be incorporated into initial examination during reception and resuscitation of injured patients. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.
Multiscale Analysis of the Roughness Effect on Lubricated Rough Contact
Demirci , Ibrahim; MEZGHANI , Sabeur; YOUSFI , Mohammed; El Mansori , Mohamed
2014-01-01
Determining friction is as equally essential as determining the film thickness in the lubricated contact, and is an important research subject. Indeed, reduction of friction in the automotive industry is important for both the minimization of fuel consumption as well as the decrease in the emissions of greenhouse gases. However, the progress in friction reduction has been limited by the difficulty in understanding the mechanism of roughness effects on friction. It was observed that micro-surf...
DEFF Research Database (Denmark)
Mody, Astrid
2012-01-01
The introduction of Light Emitting Diodes (LEDs) in the built environment has encouraged myriad applications, often embedded in surfaces as an integrated part of the architecture. Thus the wall as responsive luminous skin is becoming, if not common, at least familiar. Taking into account how wall...
DEFF Research Database (Denmark)
Mody, Astrid
2012-01-01
The introduction of Light Emitting Diodes (LEDs) in the built environment has encouraged myriad applications, often embedded in surfaces as an integrated part of the architecture. Thus the wall as responsive luminous skin is becoming, if not common, at least familiar. Taking into account how walls...... have encouraged architectural thinking of enclosure, materiality, construction and inhabitation in architectural history, the paper’s aim is to define new directions for the integration of LEDs in walls, challenging the thinking of inhabitation and program. This paper introduces the notion...... of “ambiguous walls” as a more “critical” approach to design [1]. The concept of ambiguous walls refers to the diffuse status a lumious and possibly responsive wall will have. Instead of confining it can open up. Instead of having a static appearance, it becomes a context over time. Instead of being hard...
Percolation characteristics of solvent invasion in rough fractures under miscible conditions
Korfanta, M.; Babadagli, T.; Develi, K.
2017-10-01
Surface roughness and flow rate effects on the solvent transport under miscible conditions in a single fracture are studied. Surface replicas of seven different rocks (marble, granite, and limestone) are used to represent different surface roughness characteristics each described by different mathematical models including three fractal dimensions. Distribution of dyed solvent is investigated at various flow rate conditions to clarify the effect of roughness on convective and diffusive mixing. After a qualitative analysis using comparative images of different rocks, the area covered by solvent with respect to time is determined to conduct a semi-quantitative analysis. In this exercise, two distinct zones are identified, namely the straight lines obtained for convective (early times) and diffusive (late times) flow. The bending point between these two lines is used to point the transition between the two zones. Finally, the slopes of the straight lines and the bending points are correlated to five different roughness parameters and the rate (Peclet number). It is observed that both surface roughness and flow rate have significant effect on solvent spatial distribution. The largest area covered is obtained at moderate flow rates and hence not only the average surface roughness characteristic is important, but coessentially total fracture surface area needs to be considered when evaluating fluid distribution. It is also noted that the rate effect is critically different for the fracture samples of large grain size (marbles and granite) compared to smaller grain sizes (limestones). Variogram fractal dimension exhibits the strongest correlation with the maximum area covered by solvent, and display increasing trend at the moderate flow rates. Equations with variogram surface fractal dimension in combination with any other surface fractal parameter coupled with Peclet number can be used to predict maximum area covered by solvent in a single fracture, which in turn can be
Rough surface mitigates electron and gas emission
International Nuclear Information System (INIS)
Molvik, A.
2004-01-01
Heavy-ion beams impinging on surfaces near grazing incidence (to simulate the loss of halo ions) generate copious amounts of electrons and gas that can degrade the beam. We measured emission coefficients of η e (le) 130 and η 0 ∼ 10 4 respectively, with 1 MeV K + incident on stainless steel. Electron emission scales as η e ∝ 1/cos(θ), where θ is the ion angle of incidence relative to normal. If we were to roughen a surface by blasting it with glass beads, then ions that were near grazing incidence (90 o ) on smooth surface would strike the rims of the micro-craters at angles closer to normal incidence. This should reduce the electron emission: the factor of 10 reduction, Fig. 1(a), implies an average angle of incidence of 62 o . Gas desorption varies more slowly with θ (Fig. 1(b)) decreasing a factor of ∼2, and along with the electron emission is independent of the angle of incidence on a rough surface. In a quadrupole magnet, electrons emitted by lost primary ions are trapped near the wall by the magnetic field, but grazing incidence ions can backscatter and strike the wall a second time at an azimuth where magnetic field lines intercept the beam. Then, electrons can exist throughout the beam (see the simulations of Cohen, HIF News 1-2/04). The SRIM (TRIM) Monte Carlo code predicts that 60-70% of 1 MeV K + ions backscatter when incident at 88-89 o from normal on a smooth surface. The scattered ions are mostly within ∼10 o of the initial direction but a few scatter by up to 90 o . Ion scattering decreases rapidly away from grazing incidence, Fig. 1(c ). At 62 deg. the predicted ion backscattering (from a rough surface) is 3%, down a factor of 20 from the peak, which should significantly reduce electrons in the beam from lost halo ions. These results are published in Phys. Rev. ST - Accelerators and Beams
Verdonschot, N.J.J.; Huiskes, H.W.J.
1998-01-01
Although stress analyses have shown that the mechanical endurance of cemented femoral THA reconstructions is served by stems that firmly bond to their cement mantles, retrieval studies suggest that this may be difficult to achieve. Clinical studies with roentgen stereophotogrammetric analyses have
Ultrasonic backward radiation on painted rough interface
International Nuclear Information System (INIS)
Kwon, Yong Gyu; Yoon, Seok Soo; Kwon, Sung Duck
2002-01-01
The angular dependence(profile) of backscattered ultrasound was measured for steel and brass specimens with periodical surface roughness (1-71μm). Backward radiations showed more linear dependency than normal profile. Direct amplitude increased and averaging amplitude decreased with surface roughness. Painting treatment improved the linearity in direct backward radiation below roughness of 0.03. Scholte and Rayleigh-like waves were observed in the spectrum of averaging backward radiation on periodically rough surface. Painting on periodically rough surface could be used in removing the interface mode effect by periodic roughness.
International Nuclear Information System (INIS)
Takekura, K.; Kawamura, S.; Itoh, K.
2003-01-01
An on-farm experiment in which 361 metric tons of rough rice was stored in a silo from November until July was conducted at a country elevator in Hokkaido to develop new techniques for storing rough rice in cold regions. The temperature of the rough rice near the inner silo wall decreased to below ice point (-5°C) due to natural heat radiation in winter, which the temperature of the rough rice in the center of the silo was maintained at almost the same temperature as that at the beginning of storage (5°C). Ventilation in the upper vacant space of the silo prevented moisture condensation on the inside surface of the silo during storage. When the cold rough rice was unloaded from the silo in summer, an unheated forced-air drier was used to increase the temperature of rough rice to above the dew point temperature of surrounding air. During the unloading and rewarming process, the moisture content of the rough rice increased due to moisture condensation on the grain from the air. However, the husks first absorbed the condensation and then the moisture slowly permeated into the brown rice kernel. Thus the rewarming process didn't cause any fissures in the brown rice. The results of the experiment indicate that condensation on rough rice doesn't give rise to any problems
CFD simulation of the atmospheric boundary layer: wall function problems
Blocken, B.J.E.; Stathopoulos, T.; Carmeliet, J.
2007-01-01
Accurate Computational Fluid Dynamics (CFD) simulations of atmospheric boundary layer (ABL) flow are essential for a wide variety of atmospheric studies including pollutant dispersion and deposition. The accuracy of such simulations can be seriously compromised when wall-function roughness
Straight-Line: A nuclear material storage information management system
International Nuclear Information System (INIS)
Nilsen, C.; Mangan, D.
1995-01-01
Sandia National Laboratories is developing Straight-Line -- a pilot system to demonstrate comprehensive monitoring of nuclear material in storage. Straight-Line is an integrated system of sensors providing information that will enhance the safety, security, and international accountability of stored nuclear material. The goals of this effort are to: (1) Provide the right sensor information to the right user immediately. (2) Reduce the expenses, risks, and frequency of human inspection of the material. (3) Provide trustworthy data to international inspectors to minimize their need to make on site inspections. In pursuit of these goals, Straight-Line unites technology from Sandia's Authenticated Item Monitoring System (AIMS) and other programs to communicate the authenticated status of the monitored item back to central magazine receivers. Straight-Line, however, incorporates several important features not found in previous systems: (1) Information Security -- the ability to collect and safely disseminate both classified and unclassified sensor data to users on a need-to-know basis. (2) Integrate into a single system the monitoring needs of safety, security, and international accountability. (3) Incorporate the use of sensors providing analog or digital output. This paper will present the overall architecture and status of the Straight-Line project
Preferences of AP position of the straight Caucasian facial profile.
Mees, Steven; Jiménez Bellinga, Raúl; Mommaerts, Maurice Y; De Pauw, Guy A M
2013-12-01
Several investigators have compared the perception of profile attractiveness between professional and non-professional people, different groups of clinicians, and different ethnic groups. Our aim was to study preferences for facial protrusion in the lateral view for a straight Class I profile and to study the influence of gender, age, sex preference, and profession. Portrait images of one male and one female model with a Class I occlusal relationship were warped into nine different antero-posterior positions. An internet site was established to reach as many people as possible, and a request was sent by email to participate in a scientific experiment. Finally, 1707 Caucasion assessors could be grouped. The preferred male profile is the straight full ante profile. For a feminine facial profile, the straight average and the straight 2/3 ante profiles were perceived as the most attractive. Surgeons tended to give significantly higher scores to attractive (ante) profiles, which correlated strongly with scores of the orthodontists. Whenever possible with combined orthodontic/surgery treatment, straight ante profiles should be aimed for. Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
Visual straight-ahead preference in saccadic eye movements.
Camors, Damien; Trotter, Yves; Pouget, Pierre; Gilardeau, Sophie; Durand, Jean-Baptiste
2016-03-15
Ocular saccades bringing the gaze toward the straight-ahead direction (centripetal) exhibit higher dynamics than those steering the gaze away (centrifugal). This is generally explained by oculomotor determinants: centripetal saccades are more efficient because they pull the eyes back toward their primary orbital position. However, visual determinants might also be invoked: elements located straight-ahead trigger saccades more efficiently because they receive a privileged visual processing. Here, we addressed this issue by using both pro- and anti-saccade tasks in order to dissociate the centripetal/centrifugal directions of the saccades, from the straight-ahead/eccentric locations of the visual elements triggering those saccades. Twenty participants underwent alternating blocks of pro- and anti-saccades during which eye movements were recorded binocularly at 1 kHz. The results confirm that centripetal saccades are always executed faster than centrifugal ones, irrespective of whether the visual elements have straight-ahead or eccentric locations. However, by contrast, saccades triggered by elements located straight-ahead are consistently initiated more rapidly than those evoked by eccentric elements, irrespective of their centripetal or centrifugal direction. Importantly, this double dissociation reveals that the higher dynamics of centripetal pro-saccades stem from both oculomotor and visual determinants, which act respectively on the execution and initiation of ocular saccades.
Straight-Line -- A nuclear material storage information management system
Energy Technology Data Exchange (ETDEWEB)
Nilsen, C. [Sandia National Labs., Livermore, CA (United States); Mangan, D. [Sandia National Labs., Albuquerque, NM (United States)
1995-12-31
Sandia National Laboratories is developing Straight-Line -- a pilot system to demonstrate comprehensive monitoring of nuclear material in storage. Straight-Line is an integrated system of sensors providing information that will enhance the safety, security, and international accountability of stored nuclear material. The goals of this effort are to (1) Provide the right sensor information to the right user in a timely manner. (2) Reduce the expenses, risks, and frequency of human inspection of the material. (3) Provide trustworthy data to international inspectors to minimize their need to make on site inspections. In pursuit of these goals, Straight-Line unites technology from Sandia`s Authenticated Item Monitoring System (AIMS) and other programs to communicate the authenticated status of the monitored item back to central magazine receivers. Straight-Line, however, incorporates several important features not found in previous systems: (1) Information Security -- the ability to collect and safely disseminate both classified and unclassified sensor data to users on a need-to-know basis. (2) Integrate into a single system the monitoring needs of safety, security, and international accountability. (3) Incorporate the use of sensors providing analog or digital output. This paper will present the overall architecture and status of the Straight-Line project.
Straight-Line: A nuclear material storage information management system
Energy Technology Data Exchange (ETDEWEB)
Nilsen, C.; Mangan, D.
1995-07-01
Sandia National Laboratories is developing Straight-Line -- a pilot system to demonstrate comprehensive monitoring of nuclear material in storage. Straight-Line is an integrated system of sensors providing information that will enhance the safety, security, and international accountability of stored nuclear material. The goals of this effort are to: (1) Provide the right sensor information to the right user immediately. (2) Reduce the expenses, risks, and frequency of human inspection of the material. (3) Provide trustworthy data to international inspectors to minimize their need to make on site inspections. In pursuit of these goals, Straight-Line unites technology from Sandia`s Authenticated Item Monitoring System (AIMS) and other programs to communicate the authenticated status of the monitored item back to central magazine receivers. Straight-Line, however, incorporates several important features not found in previous systems: (1) Information Security -- the ability to collect and safely disseminate both classified and unclassified sensor data to users on a need-to-know basis. (2) Integrate into a single system the monitoring needs of safety, security, and international accountability. (3) Incorporate the use of sensors providing analog or digital output. This paper will present the overall architecture and status of the Straight-Line project.
Straight eye for the gay guy: composing queerness.
Alexander, Jonathan
2010-01-01
Drawing on the work of Didier Eribon and his theorization of the construction of gay male subjectivity, this article examines different "texts," broadly defined, that grapple specifically with straight men attempting to represent male homosexuality: Norman Mailer's essay, "The Homosexual Villain"; the Bravo reality television series Boy Meets Boy, and Michael Griffith's short story, "Hooper Gets a Perm." These texts represent attempts by straight authors to grapple with queer experience in ways that move the imagination of queers beyond simple stereotypes or uncritical explorations of the sexual "other." In the process of examining these texts, the following questions are addressed: What happens when a straight man attempts to represent a gay man? Does he "get it right," and is such a question even useful? More specifically, what is the value in having straights imagine queerness? Is such an imagining possible? Is such desirable? And, if so, what are the contours of such an imagining-as well as its possibilities and limitations, pedagogically, personally, and politically? Ultimately, I contend that the straight imagining of queerness offers rich potential for mutual understanding; furthermore, attempting to understand what goes into the making of those representations tells us much about how queerness circulates in our culture as a subject, a figure of discussion, contention, and representation.
Straight-Line -- A nuclear material storage information management system
International Nuclear Information System (INIS)
Nilsen, C.; Mangan, D.
1995-01-01
Sandia National Laboratories is developing Straight-Line -- a pilot system to demonstrate comprehensive monitoring of nuclear material in storage. Straight-Line is an integrated system of sensors providing information that will enhance the safety, security, and international accountability of stored nuclear material. The goals of this effort are to (1) Provide the right sensor information to the right user in a timely manner. (2) Reduce the expenses, risks, and frequency of human inspection of the material. (3) Provide trustworthy data to international inspectors to minimize their need to make on site inspections. In pursuit of these goals, Straight-Line unites technology from Sandia's Authenticated Item Monitoring System (AIMS) and other programs to communicate the authenticated status of the monitored item back to central magazine receivers. Straight-Line, however, incorporates several important features not found in previous systems: (1) Information Security -- the ability to collect and safely disseminate both classified and unclassified sensor data to users on a need-to-know basis. (2) Integrate into a single system the monitoring needs of safety, security, and international accountability. (3) Incorporate the use of sensors providing analog or digital output. This paper will present the overall architecture and status of the Straight-Line project
DEFF Research Database (Denmark)
Nakamura, T; Bay, Niels
1998-01-01
A new friction testing method based on combined forward conical can-backward straight can extrusion is proposed in order to evaluate friction characteristics in severe metal forming operations. By this method the friction coefficient along the conical punch surface is determined knowing...... the friction coefficient along the die wall. The latter is determined by a combined forward and backward can extrusion of straight cans. Calibration curves determining the relationship between punch travel, can heights, and friction coefficient for the two rests are calculated based on a rigid-plastic FEM...... analysis. Experimental friction tests are carried out in a mechanical press with aluminium alloy A6061 as the workpiece material and different kinds of lubricants. They confirm that the theoretical analysis results irt reasonable values for the friction coefficient....
Yin, Jun; Yao, Xueping; Liou, Jiun-You; Sun, Wei; Sun, Ya-Sen; Wang, Yong
2013-11-26
Membranes with uniform, straight nanopores have important applications in diverse fields, but their application is limited by the lack of efficient producing methods with high controllability. In this work, we reported on an extremely simple and efficient strategy to produce such well-defined membranes. We demonstrated that neutral solvents were capable of annealing amphiphilic block copolymer (BCP) films of polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) with thicknesses up to 600 nm to the perpendicular orientation within 1 min. Annealing in neutral solvents was also effective to the perpendicular alignment of block copolymers with very high molecular weights, e.g., 362 000 Da. Remarkably, simply by immersing the annealed BCP films in hot ethanol followed by drying in air, the originally dense BCP films were nondestructively converted into porous membranes containing highly ordered, straight nanopores traversing the entire thickness of the membrane (up to 1.1 μm). Grazing incident small-angle X-ray spectroscopy confirmed the hexagonal ordering of the nanopores over large areas. We found that the overflow of P2VP chains from their reservoir P2VP cylinders and the deformation of the PS matrix in the swelling process contributed to the transformation of the solid P2VP cylinders to empty straight pores. The pore diameters can be tuned by either changing the swelling temperatures or depositing thin layers of metal oxides on the preformed membranes via atomic layer deposition with a subnanometer accuracy. To demonstrate the application of the obtained porous membranes, we used them as templates and produced centimeter-scale arrays of aligned nanotubes of metal oxides with finely tunable wall thicknesses.
Hanratty, Thomas J.
1980-01-01
This paper gives an account of research on the structure of turbulence close to a solid boundary. Included is a method to study the flow close to the wall of a pipe without interferring with it. (Author/JN)
Rough set classification based on quantum logic
Hassan, Yasser F.
2017-11-01
By combining the advantages of quantum computing and soft computing, the paper shows that rough sets can be used with quantum logic for classification and recognition systems. We suggest the new definition of rough set theory as quantum logic theory. Rough approximations are essential elements in rough set theory, the quantum rough set model for set-valued data directly construct set approximation based on a kind of quantum similarity relation which is presented here. Theoretical analyses demonstrate that the new model for quantum rough sets has new type of decision rule with less redundancy which can be used to give accurate classification using principles of quantum superposition and non-linear quantum relations. To our knowledge, this is the first attempt aiming to define rough sets in representation of a quantum rather than logic or sets. The experiments on data-sets have demonstrated that the proposed model is more accuracy than the traditional rough sets in terms of finding optimal classifications.
Surface roughness control by extreme ultraviolet (EUV) radiation
Ahad, Inam Ul; Obeidi, Muhannad Ahmed; Budner, Bogusław; Bartnik, Andrzej; Fiedorowicz, Henryk; Brabazon, Dermot
2017-10-01
Surface roughness control of polymeric materials is often desirable in various biomedical engineering applications related to biocompatibility control, separation science and surface wettability control. In this study, Polyethylene terephthalate (PET) polymer films were irradiated with Extreme ultraviolet (EUV) photons in nitrogen environment and investigations were performed on surface roughness modification via EUV exposure. The samples were irradiated at 3 mm and 4 mm distance from the focal spot to investigate the effect of EUV fluence on topography. The topography of the EUV treated PET samples were studied by AFM. The detailed scanning was also performed on the sample irradiated at 3 mm. It was observed that the average surface roughness of PET samples was increased from 9 nm (pristine sample) to 280 nm and 253 nm for EUV irradiated samples. Detailed AFM studies confirmed the presence of 1.8 mm wide period U-shaped channels in EUV exposed PET samples. The walls of the channels were having FWHM of about 0.4 mm. The channels were created due to translatory movements of the sample in horizontal and transverse directions during the EUV exposure. The increased surface roughness is useful for many applications. The nanoscale channels fabricated by EUV exposure could be interesting for microfluidic applications based on lab-on-a-chip (LOC) devices.
Heat transfer and friction on smooth and rough test rods
International Nuclear Information System (INIS)
Franken, W.M.P.; Hoogland, H.; Deijman, P.
1977-06-01
Results are reported on heat transfer and pressure drop tests on one smooth and nine rough test rods in an annular geometry. The wall roughness consisted of transversal ribs with various roughness pitches, rib heights and rib widths. The tests were performed with air as coolant under a wide range of experimental conditions: 10 5 5 , 1.1 2. Special attention has been given to the effect of variation of the physical coolant properties over the flow cross section. This effect could be described by the power function (Tsub(w)/Tsub(b))sup(-0.3l) in additional systematic variation of the heat transfer could be recognized, dependent on the coolant temperature level. The experimental results were correlated by the equation St = C(Tsub(in)) Resup(-0.2) Prsup(-0.6) (Tsub(w)/Tsub(b)sup(-0.31). Values of C(Tsub(in)) are given in tabular form. The thermal entrance effect has been measured on various test rods. A substantial reduction of the heat transfer coefficient was almost constant along the rough test rods
Wake Instabilities Behind Discrete Roughness Elements in High Speed Boundary Layers
Choudhari, Meelan; Li, Fei; Chang, Chau-Lyan; Norris, Andrew; Edwards, Jack
2013-01-01
Computations are performed to study the flow past an isolated, spanwise symmetric roughness element in zero pressure gradient boundary layers at Mach 3.5 and 5.9, with an emphasis on roughness heights of less than 55 percent of the local boundary layer thickness. The Mach 5.9 cases include flow conditions that are relevant to both ground facility experiments and high altitude flight ("cold wall" case). Regardless of the Mach number, the mean flow distortion due to the roughness element is characterized by long-lived streamwise streaks in the roughness wake, which can support instability modes that did not exist in the absence of the roughness element. The higher Mach number cases reveal a variety of instability mode shapes with velocity fluctuations concentrated in different localized regions of high base flow shear. The high shear regions vary from the top of a mushroom shaped structure characterizing the centerline streak to regions that are concentrated on the sides of the mushroom. Unlike the Mach 3.5 case with nearly same values of scaled roughness height k/delta and roughness height Reynolds number Re(sub kk), the odd wake modes in both Mach 5.9 cases are significantly more unstable than the even modes of instability. Additional computations for a Mach 3.5 boundary layer indicate that the presence of a roughness element can also enhance the amplification of first mode instabilities incident from upstream. Interactions between multiple roughness elements aligned along the flow direction are also explored.
A mathematical model for camera calibration based on straight lines
Directory of Open Access Journals (Sweden)
Antonio M. G. Tommaselli
2005-12-01
Full Text Available In other to facilitate the automation of camera calibration process, a mathematical model using straight lines was developed, which is based on the equivalent planes mathematical model. Parameter estimation of the developed model is achieved by the Least Squares Method with Conditions and Observations. The same method of adjustment was used to implement camera calibration with bundles, which is based on points. Experiments using simulated and real data have shown that the developed model based on straight lines gives results comparable to the conventional method with points. Details concerning the mathematical development of the model and experiments with simulated and real data will be presented and the results with both methods of camera calibration, with straight lines and with points, will be compared.
An electromagnetic model for post-wall waveguide building blocks
Coenen, T.J.; Bekers, D.J.; Tauritz, J.L.; Vliet, van F.E.
2010-01-01
During the past five years, dielectric and metallic post-wall waveguides (PWWGs) have been analyzed at TNO Defence, Security and Safety, using both an integral equation approach and a modal approach. The model developed focuses on TEn0 modes facilitating the analysis of infinitelylong, straight
Design and Measurement of Metallic Post-Wall Waveguide Components
Coenen, T.J.; Bekers, D.J.; Tauritz, J.L.; Vliet, F.E. van
2009-01-01
Abstract—In this paper we discuss the design and measurement of a set of metallic post-wall waveguide components for antenna feed structures. The components are manufactured on a single layer printed circuit board and excited by a grounded coplanar waveguide. For a straight transmission line, a 90°
Effect of surface roughness on ultrasonic echo amplitude in aluminium-copper alloy castings
International Nuclear Information System (INIS)
Ambardar, R.; Pathak, S.D.; Prabhakar, O.; Jayakumar, T.
1996-01-01
In the present investigation, the influence of test surface roughness on ultrasonic back-wall echo (BWE) amplitude in Al-4.5%Cu alloy cast specimens has been studied. The results indicate that as the value of surface roughness of the specimen increases, the value of relating BWE amplitude at a given probe frequency decreases. However, under the present set of experimental conditions, the decrease in BWE amplitude with the increase in surface roughness of the test specimen is found to be appreciable at 10 MHz probe frequency. (author)
Bent versus straight tips in micropulsed longitudinal phacoemulsification.
Stagg, Brian C; Gupta, Isha; Cahoon, Judd; Ronquillo, Cecinio; Shi, Dallas; Zaugg, Brian; Gardiner, Gareth; Barlow, William R; Pettey, Jeff H; Aabid Farukhi, M; Jensen, Jason; Olson, Randall J
2015-10-01
The aim of this study was to evaluate bent and straight phacoemulsification tips to determine which tip is more efficient in removal of lens fragments, using micropulsed longitudinal ultrasound in phacoemulsification. In vitro laboratory study. The John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, was the study setting. Pig lenses hardened in a manner comparable with dense human cataracts were cut into 2-mm cubes and removed with micropulsed longitudinal ultrasound using settings previously shown to be optimally efficient (6 milliseconds on and 6 milliseconds off for a bent tip). To verify this time as most efficient for a straight tip, we also tested times of 5, 6, and 7 milliseconds time on and off. The tips were either straight or with a 20-degree bend. Twenty cubes were used for each comparative run. For the straight tip, 6 milliseconds on (1.56 ± 0.815 seconds) was significantly more efficient than 7 milliseconds on (2.45 ± 1.56 seconds, p = 0.001) and not significantly more efficient than 5 milliseconds on (1.69 ± 0.86 seconds, p = 0.43). Five milliseconds off time (1.45 ± 0.76s) was more efficient than 6 milliseconds (2.06 ± 1.37 seconds, p = 0.004) and 7 milliseconds off (2.18 ± 1.24s, p = 0.001). The straight tip was more efficient than the bent tip (1.38 ± 0.83 versus 2.93 ± 2.14 seconds, p = 0.006). Results are contrary to accepted common belief. Micropulsed longitudinal phacoemulsification is more efficient with a straight rather than a bent tip. Copyright © 2015 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.
A Method to Establishing Tube Plugging Criterion for Heat Exchangers with Straight Tubes
Energy Technology Data Exchange (ETDEWEB)
Kim, Hyungnam [KHNP CRI, Daejeon (Korea, Republic of)
2016-10-15
The difference of thermal expansion coefficients between the shell and tube materials causes the stress in axial direction of tube. Because of the axial stress due to thermal load, the straight tubes are used for heat exchangers operated in low temperature such as CCW (Component Cooling Water) heat exchangers and condensers. It is inevitable for the materials of the components to be degraded as the power plants become older. The degradation accompanies increasing maintenance cost as well as creating safety issues. The materials and wall thickness of heat exchanger tubes in nuclear power plants are selected to withstand system temperature, pressure, and corrosion. There are many codes and standards to be referred for calculating the minimum thickness of the heat exchanger tube in the designing stage. However, the codes and standards related to show the tube plugging criteria may not exist currently. In this paper, a method to establish the tube plugging criteria of BOP heat exchangers, which is based on the USNRC Regulatory Guide 1.121, is introduced and the tube plugging criteria for the TPCCW heat exchanger of Yonggwang NPP No. 1 and 2. A method to establish the tube plugging criteria of heat exchangers with straight tubes are introduced based on the USNRC Regulatory Guide 1.121. As an example, the tube plugging criterion for the CCW heat exchanger of a nuclear power plant is provided.
Radical heterosexuality: Straight teacher activism in schools : Does ally-led activism work?
Directory of Open Access Journals (Sweden)
Leigh Potvin
2016-06-01
Here, I explore the efficacy of straight teacher allies, the importance of understanding straight privilege, and the significance of radical heterosexuality for straight people doing LGBTQ activism. Relying on queer theory and decolonizing/Indigenous queer theory, I argue that it is necessary for straight teachers to acknowledge their straight privilege in order to challenge homophobia's companions: heterosexism and heteronormativity. In addressing the latter two covert forms of oppression in schools, teachers and students could shift into deeper, more effective resistance measures.
Production of short straight sections hits 100 units
2005-01-01
The 100th short straight section for the Large Hadron Collider was assembled at CERN at the beginning of April. These units combine superconducting quadrupoles and other multipole corrector magnets, housed in their cryostats, which are used to guide, focus and fine-tune the beam in the LHC. Building 904, where the 474 short straight sections are being assembled, is often called "Lego Land" by the workers, with a touch of humor and pride because of the wide variety of these sets of magnets and cryostats .
Commissioning of the cryogenics of the LHC long straight sections
International Nuclear Information System (INIS)
Perin, A.; Casas-Cubillos, J.; Claudet, S.; Darve, C.; Ferlin, G.; Millet, F.; Parente, C.; Rabehl, R.; Soubiran, M.; van Weelderen, R.; Wagner, U.
2010-01-01
The LHC is made of eight circular arcs interspaced with eight Long Straight Sections (LSS). Most powering interfaces to the LHC are located in these sections where the particle beams are focused and shaped for collision, cleaning and acceleration. The LSSs are constituted of several unique cryogenic devices and systems like electrical feed-boxes, standalone superconducting magnets, superconducting links, RF cavities and final focusing superconducting magnets. This paper presents the cryogenic commissioning and the main results obtained during the first operation of the LHC Long Straight Sections.
A generalized, periodic nonlinearity-reduced interferometer for straightness measurements
International Nuclear Information System (INIS)
Wu Chienming
2008-01-01
Periodic nonlinearity is a systematic error limiting the accuracy of displacement measurements at the nanometer level. However, an interferometer with a displacement measurement accuracy of less than 1 nm is required in nanometrology and in fundamental scientific research. To meet this requirement, a generalized, periodic nonlinearity-reduced interferometer, based on three construction principles has been developed for straightness measurements. These three construction principles have resulted in an interferometer with a highly stable design with reduced periodic nonlinearity. Verifications by a straightness interferometer have demonstrated that the periodic nonlinearity was less than 40 pm. The results also demonstrate that the interferometer design is capable of subnanometer accuracy and is useful in nanometrology
Commissioning of the Cryogenics of the LHC Long Straight Sections
Perin, A; Claudet, S; Darve, C; Ferlin, G; Millet, F; Parente, C; Rabehl, R; Soubiran, M; van Weelderen, R; Wagner, U
2010-01-01
The LHC is made of eight circular arcs interspaced with eight Long Straight Sections (LSS). Most powering interfaces to the LHC are located in these sections where the particle beams are focused and shaped for collision, cleaning and acceleration. The LSSs are constituted of several unique cryogenic devices and systems like electrical feed-boxes, standalone superconducting magnets, superconducting links, RF cavities and final focusing superconducting magnets. This paper presents the cryogenic commissioning and the main results obtained during the first operation of the LHC Long Straight Sections.
Rouhi, Amirreza; Chung, Daniel; Hutchins, Nicholas
2017-11-01
Direct numerical simulations (DNSs) are reported for open channel flow over streamwise-alternating patches of smooth and fully rough walls. Owing to the streamwise periodicity, the flow configuration is composed of a step change from smooth to rough, and a step change from rough to smooth. The friction Reynolds number varies from 443 over the smooth patch to 715 over the rough patch. The flow is thoroughly studied by mean and fluctuation profiles, and spectrograms. The detailed flow from DNS reveals discrepancies of up to 50% among the various definitions of the internal-layer thickness, with apparent power-law exponents differing by up to 60%. The definition based on the logarithmic slope of the velocity profile, as proposed by Chamorro et al. (Boundary-Layer Meteorol., vol. 130, 2009, pp. 29-41), is most consistent with the physical notion of the internal layer; this is supported by the defect similarity based on this internal-layer thickness, and the streamwise homogeneity of the dissipation length-scale within this internal layer. The statistics inside this internal-layer, and the growth of the internal layer itself, are minimally affected by the streamwise periodicity when the patch length is at least six times the channel height.
Motor control patterns during an active straight leg raise in pain-free subjects.
Beales, Darren John; O'Sullivan, Peter Bruce; Briffa, N Kathryn
2009-01-01
Repeated measures. To investigate motor control (MC) patterns of normal subjects during the low level physical load of the active straight leg raise (ASLR). Aberrant MC patterns, as observed with the ASLR test, are considered to be a mechanism for ongoing pain and disability in subjects with chronic musculoskeletal pelvic girdle pain. These patterns may not only affect the provision of lumbopelvic stability, but also respiration and the control of continence. Greater understanding of MC patterns in pain-free subjects may improve the management of pelvic girdle pain. METHODS.: Fourteen pain-free nulliparous women were examined during the ASLR. Electromyography of the anterior abdominal wall, right chest wall and the anterior scaleni, intraabdominal pressure (IAP), intrathoracic pressure (ITP), respiratory rate, pelvic floor kinematics, and downward leg pressure of the nonlifted leg were compared between a left and right ASLR. There was greater activation of obliquus internus abdominis and obliquus externus abdominis on the side of the ASLR. The predominant pattern of activation for the chest wall was tonic activation during an ipsilateral ASLR, and phasic respiratory activation lifting the contralateral leg. Respiratory fluctuation of both IAP and ITP did not differ lifting either leg. The baseline shifts of these pressure variables in response to the physical demand of lifting the leg was also the same either side. There was no difference in respiratory rate, pelvic floor kinematics, or downward leg pressure. Pain-free subjects demonstrate a predominant pattern of greater ipsilateral tonic activation of the abdominal wall and chest wall on the side of the ASLR. This was achieved with minimal apparent disruption to IAP and ITP. The findings of this study demonstrate the plastic nature of the abdominal cylinder and the flexibility of the neuromuscular system in controlling load transference during an ASLR.
Computer simulations of a rough sphere fluid
International Nuclear Information System (INIS)
Lyklema, J.W.
1978-01-01
A computer simulation is described on rough hard spheres with a continuously variable roughness parameter, including the limits of smooth and completely rough spheres. A system of 500 particles is simulated with a homogeneous mass distribution at 8 different densities and for 5 different values of the roughness parameter. For these 40 physically different situations the intermediate scattering function for 6 values of the wave number, the orientational correlation functions and the velocity autocorrelation functions have been calculated. A comparison has been made with a neutron scattering experiment on neopentane and agreement was good for an intermediate value of the roughness parameter. Some often made approximations in neutron scattering experiments are also checked. The influence of the variable roughness parameter on the correlation functions has been investigated and three simple stochastic models studied to describe the orientational correlation function which shows the most pronounced dependence on the roughness. (Auth.)
Axis Problem of Rough 3-Valued Algebras
Institute of Scientific and Technical Information of China (English)
Jianhua Dai; Weidong Chen; Yunhe Pan
2006-01-01
The collection of all the rough sets of an approximation space has been given several algebraic interpretations, including Stone algebras, regular double Stone algebras, semi-simple Nelson algebras, pre-rough algebras and 3-valued Lukasiewicz algebras. A 3-valued Lukasiewicz algebra is a Stone algebra, a regular double Stone algebra, a semi-simple Nelson algebra, a pre-rough algebra. Thus, we call the algebra constructed by the collection of rough sets of an approximation space a rough 3-valued Lukasiewicz algebra. In this paper,the rough 3-valued Lukasiewicz algebras, which are a special kind of 3-valued Lukasiewicz algebras, are studied. Whether the rough 3-valued Lukasiewicz algebra is a axled 3-valued Lukasiewicz algebra is examined.
Linear Motion Systems. A Modular Approach for Improved Straightness Performance
Nijsse, G.J.P.
2001-01-01
This thesis deals with straight motion systems. A modular approach has been applied in order to find ways to improve the performance. The main performance parameters that are considered are position accuracy, repeatability and, to a lesser extent, cost. Because of the increasing requirements to
Modeling plasma flow in straight and curved solenoids
International Nuclear Information System (INIS)
Boercker, D.B.; Sanders, D.M.; Storer, J.; Falabella, S.
1991-01-01
The ''flux-tube'' model originated by Morozov is a very simple and numerically efficient method for simulating ion motion in plasma filters. In order to test its utility as a design tool, we compare the predictions of the model to recent experimental measurements of plasma flow in both straight and curved solenoids
Steam cracking of hydrocarbons 3. Straight-run naphtha
Bajus, M.; Vesely, V.; Leclercq, P.A.; Rijks, J.A.
1980-01-01
Steam cracking of straight-run naphtha from Romashkino crude oil was investigated in quartz and stainless steel reactors with a relatively large ratio of Inner surface to volume. The experiments were performed at atmospheric pressure at 780-800 OC for starting ratios of steam to naphtha between 0.5
Setting the Record Straight on "High-Yield" Strategies
Marzano, Robert J.
2009-01-01
Widely credited with proposing nine "high-yield" instructional strategies, author Robert J. Marzano sets the record straight about the broader number of strategies identified by the research. He provides a list of 41 strategies and suggests more nuanced ways of using, observing, and evaluating them. (Contains 1 figure.)
The Dugdale solution for two unequal straight cracks weakening
Indian Academy of Sciences (India)
A crack arrest model is proposed for an inﬁnite elastic perfectly-plastic plate weakened by two unequal, quasi-static, collinear straight cracks. The Dugdale model solution is obtained for the above problem when the developed plastic zones are subjected to normal cohesive quadratically varying yield point stress. Employing ...
Body image in gay and straight men: a qualitative study.
Morgan, John F; Arcelus, Jon
2009-11-01
Recent research has emphasized vulnerability to eating disorders in gay men, with calls for research on causality, cultural factors and focus on a younger age cohort. This study aimed to examine body image and related eating behaviours in younger gay and straight men. Qualitative study using a sample of gay and straight male university students, applying audiotaped and transcribed depth interview subjected to interpretative phenomenological analysis. Fifteen young men (18-24) with a spectrum of sexual orientation (gay, straight and bisexual) agreed to participate. Five dominant categories emerged: body image ideal, external influences, perception of body image, dieting, mechanisms for modification (diet, exercise, cosmetics) and sexual orientation. Health and aesthetic ideals appear less divorced for young men than women, offering some degree of protection from eating disorders. Nonetheless there is widespread body dissatisfaction. Media and social influences are powerful, particularly for single gay men, but the study suggests fewer differences than similarities between gay and straight men. Copyright (c) 2009 John Wiley & Sons, Ltd and Eating Disorders Association.
Stereotactic biopsy of cerebellar lesions: straight versus oblique frame positioning.
Quick-Weller, Johanna; Brawanski, Nina; Dinc, Nazife; Behmanesh, Bedjahn; Kammerer, Sara; Dubinski, Daniel; Seifert, Volker; Marquardt, Gerhard; Weise, Lutz
2017-10-26
Biospies of brain lesions with unknown entity are an everyday procedure among many neurosurgical departments. Biopsies can be performed frame-guided or frameless. However, cerebellar lesions are a special entity with a more complex approach. All biopsies in this study were performed stereotactically frame guided. Therefore, only biopsies of cerebellar lesions were included in this study. We compared whether the frame was attached straight versus oblique and we focused on diagnostic yield and complication rate. We evaluated 20 patients who underwent the procedure between 2009 and 2017. Median age was 56.5 years. 12 (60%) Patients showed a left sided lesion, 6 (30%) showed a lesion in the right cerebellum and 2 (10%) patients showed a midline lesion. The stereotactic frame was mounted oblique in 12 (60%) patients and straight in 8 (40%) patients. Postoperative CT scan showed small, clinically silent blood collection in two (10%) of the patients, one (5%) patient showed haemorrhage, which caused a hydrocephalus. He received an external ventricular drain. In both patients with small haemorrhage the frame was positioned straight, while in the patient who showed a larger haemorrhage the frame was mounted oblique. In all patients a final histopathological diagnosis was established. Cerebellar lesions of unknown entity can be accessed transcerebellar either with the stereotactic frame mounted straight or oblique. Also for cerebellar lesions the procedure shows a high diagnostic yield with a low rate of severe complications, which need further treatment.
A Straight-Talk Survival Guide for Colleges
Facione, Peter A.
2009-01-01
Times are very tough. The great majority of colleges are looking at 2009 and 2010 and beyond, in anticipation of the deepest budget cuts in more than a generation. But as bad as the financial situation may be, colleges can survive if they take swift and strong emergency action. It is time for some straight talk, starting with the realization that…
A new straight accelerator tube with U diaphragm
International Nuclear Information System (INIS)
Liu Jinhong; Lai Weiquan; Deng Yushen; Zhang Jidong
1994-01-01
After calculating the potential distribution and the particle trajectories in electrostatic accelerator tubes, a new straight tube with U diaphragm to suppress secondary particles is proposed. It's properties are demonstrated by the high voltage tests and the γ-rays measurements in the accelerator
Cardiorespiratory and metabolic responses during straight and bent knee cycling.
Mandroukas, K; Angelopoulou, N; Christoulas, K; Vrabas, I S
2000-06-01
This study examined the influence of knee angle on the cardiorespiratory system loading during submaximal and maximal stationary cycle ergometry. Experimental design and participants: eighteen untrained women (age: 21+/-1.88 years, weight: 57+/-5.75 kg, height: 165+/-5.03 cm, values are mean+/-SD) volunteered as subjects and underwent two-cycle ergometer incremental (Jaeger ER900) tests: 1) straight knee (180 degrees), 2) bent knee (140 degrees). oxygen uptake (VO2), ventilation (VE) and respiratory exchange ratio (RER) were measured continuously during each test using an open circuit spirometry and blood lactate concentration was determined by means of an enzymatic method. Comparing cycling with "straight knee" to cycling with "bent knee" at 50 W, heart rate (HR), V(E) and VO2 were significantly higher (10.6%, 12.5%, 17.8%). At 100 W, blood lactate was significantly lower (10.8%) while VO2 and RER was higher (5.5%, 7.1%). During maximal exercise, the total exercise time was significantly longer (11.2%) and VE, VO2 and HR were significantly higher during cycling with "straight knee" compared to cycling with "bent knee". No significant difference in peak lactate was evident between the two sitting positions. The results of this study indicate that cycling with bent knee requires lower oxygen uptake while pedaling with straight knee is the only way to reach VO2max during cycle testing, since the cardiorespiratory system is fully taxed.
Sensing roughness and polish direction
DEFF Research Database (Denmark)
Jakobsen, Michael Linde; Olesen, Anders Sig; Larsen, Henning Engelbrecht
2016-01-01
As a part of the work carried out in a project supported by the Danish Council for Technology and Innovation, we have investigated the option of smoothing standard CNC-machined surfaces. In the process of constructing optical prototypes, involving custom-designed optics, the development cost...... and time consumption can become prohibitive in a research budget. Machining the optical surfaces directly is expensive and time consuming. Alternatively, a more standardized and cheaper machining method can be used, calling for the object to be manually polished. During the polishing process, the operator...... needs information about the RMS-value of the surface roughness and the current direction of the scratches introduced by the polishing process. The RMS-value indicates to the operator how far he is from the final finish, and the scratch orientation is often specified by the customer in order to avoid...
Software testing in roughness calculation
International Nuclear Information System (INIS)
Chen, Y L; Hsieh, P F; Fu, W E
2005-01-01
A test method to determine the function quality provided by the software for roughness measurement is presented in this study. The function quality of the software requirements should be part of and assessed through the entire life cycle of the software package. The specific function, or output accuracy, is crucial for the analysis of the experimental data. For scientific applications, however, commercial software is usually embedded with specific instrument, which is used for measurement or analysis during the manufacture process. In general, the error ratio caused by the software would be more apparent especially when dealing with relatively small quantities, like the measurements in the nanometer-scale range. The model of 'using a data generator' proposed by NPL of UK was applied in this study. An example of the roughness software is tested and analyzed by the above mentioned process. After selecting the 'reference results', the 'reference data' was generated by a programmable 'data generator'. The filter function of 0.8 mm long cutoff value, defined in ISO 11562 was tested with 66 sinusoid data at different wavelengths. Test results from commercial software and CMS written program were compared to the theoretical data calculated from ISO standards. As for the filter function in this software, the result showed a significant disagreement between the reference and test results. The short cutoff feature for filtering at the high frequencies does not function properly, while the long cutoff feature has the maximum difference in the filtering ratio, which is more than 70% between the wavelength of 300 μm and 500 μm. Conclusively, the commercial software needs to be tested more extensively for specific application by appropriate design of reference dataset to ensure its function quality
International Nuclear Information System (INIS)
Jimenez D, H.; Colunga S, S.; Lopez C, R.; Melendez L, L.; Ramos S, J.; Cabral P, A.; Gonzalez T, L.; Chavez A, E.; Valencia A, R.
1991-06-01
Two simple and fast methods to calculate the penetration time of a longitudinal magnetic field through the wall of a long metallic tube of circular cross section are presented. The first method is based upon the proposition of an 'effective penetration thickness' given by the polar angle average of all possible straight-line transverse penetration paths of field lines through the tube wall. This method provides a quick calculation that yields a remarkably good approximation to experimental and reported values of the penetration time. In the second method the tube is considered as a RL circuit. Thus the penetration time is given by the ratio L T /R T where L T is the inductance of the tube considered as a one turn coil, and R T is the tube resistance. This method is faster to apply than the previous one but the values obtained provide only a rough approximation to the penetration time. Applications of the two methods are given for the tokamak chambers of the Japanese 'HYBTOK', the Brazilian 'TBR' and the Mexican 'Novillo'. The resulting values of the penetration time approximate very well to the reported ones in the first two cases and to the experimental one in the last. The methods are also applied to calculate the penetration time in two long tubes, one of aluminum and other of copper. Calculated values approximate very well to measured values. (Author)
Murphy, Heather Elise
2012-01-01
Lesbian, gay, bisexual, and transgender (LGBT) students face many risk factors every day when they enter their school's door. These students often fear for their safety at school, are victimized, have academic difficulties, suffer from issues with their identity development, and are at risk for suicide. School-based Gay-Straight Alliances (GSAs)…
Investigation of secondary flows in turbulent pipe flows with three-dimensional sinusoidal walls
Chan, Leon; MacDonald, Michael; Chung, Daniel; Hutchins, Nicholas; Ooi, Andrew
2017-11-01
The occurrence of secondary flows is systematically investigated via Direct Numerical Simulations (DNS) of turbulent flow in a rough wall pipe at friction Reynolds numbers of 540. In this study, the peak-to-trough height of the roughness elements, which consist of three-dimensional sinusoidal roughness, is fixed at 120 viscous units while the wavelength of the roughness elements is varied. The solidity or effective slope (ES) of the roughness ranges from the sparse regime (ES = 0.18) to the closely packed roughness/dense regime (ES = 0.72). The time-independent dispersive stresses, which arise due to the stationary features of the flow, are analysed and are found to increase with increasing roughness wavelength. These dispersive stresses are related to the occurrence of secondary flows and are maximum within the roughness canopy. Above the crest of the roughness elements, the dispersive stresses reduce to zero at wall-normal heights greater than half of the roughness wavelength. This study has found that the size and wall-normal extent of the secondary flows scales with the roughness wavelength and can reach wall-normal heights of almost half of the pipe radius.
International Nuclear Information System (INIS)
Shuchi, S.; Shimada, K.; Kamiyama, S.; Yamaguchi, H.
2002-01-01
We clarify numerically the wall friction coefficient, the distributions of velocity and shear rate, and the number of aggregated particles on steady magnetic fluid flow in a straight tube by taking into account the non-uniform distribution of mass concentration (DMC). Also the effect of DMC is clarified under the uniform and non-uniform transverse steady magnetic field. In comparison with the published data, the numerical results show good agreement with the experimental data
Vertical Equilibrium of Sheet Pile Walls with Emphasis on Toe Capacity and Plugging
DEFF Research Database (Denmark)
Iversen, Kirsten Malte; Augustesen, Anders Hust; Nielsen, Benjaminn Nordahl
Constructions including retaining walls are normally established in areas where it is impossible to conduct an excavation with inclined sides. Due to large excavation depths and due to restrictions on the deformations of the wall, it is often necessary to anchor the wall. The limited space makes...... at the pile toe to fulfil vertical equilibrium. The paper describes a case study of sheet pile walls in Aalborg Clay, and the amount of loads transferred as point loads at the pile toe for free and anchored walls is estimated. A parametric study is made for the free wall with regards to the height...... and the roughness of the wall. Due to limitations of the calculation method, the study of the anchored wall only includes variation of the roughness. For the case study, it is found that the vertical equilibrium is fulfilled for the considered free wall. An anchored wall needs a plug forming at the pile toe...
Simplified Approach to Predicting Rough Surface Transition
Boyle, Robert J.; Stripf, Matthias
2009-01-01
Turbine vane heat transfer predictions are given for smooth and rough vanes where the experimental data show transition moving forward on the vane as the surface roughness physical height increases. Consiste nt with smooth vane heat transfer, the transition moves forward for a fixed roughness height as the Reynolds number increases. Comparison s are presented with published experimental data. Some of the data ar e for a regular roughness geometry with a range of roughness heights, Reynolds numbers, and inlet turbulence intensities. The approach ta ken in this analysis is to treat the roughness in a statistical sense , consistent with what would be obtained from blades measured after e xposure to actual engine environments. An approach is given to determ ine the equivalent sand grain roughness from the statistics of the re gular geometry. This approach is guided by the experimental data. A roughness transition criterion is developed, and comparisons are made with experimental data over the entire range of experimental test co nditions. Additional comparisons are made with experimental heat tran sfer data, where the roughness geometries are both regular as well a s statistical. Using the developed analysis, heat transfer calculatio ns are presented for the second stage vane of a high pressure turbine at hypothetical engine conditions.
Effect of seabed roughness on tidal current turbines
Gupta, Vikrant; Wan, Minping
2017-11-01
Tidal current turbines are shown to have potential to generate clean energy for a negligible environmental impact. These devices, however, operate in high to moderate current regions where the flow is highly turbulent. It has been shown in flume tank experiments at IFREMER in Boulogne-Sur-Mer (France) and NAFL in the University of Minnesota (US) that the level of turbulence and boundary layer profile affect a turbine's power output and wake characteristics. A major factor that determines these marine flow characteristics is the seabed roughness. Experiments, however, cannot simulate the high Reynolds number conditions of real marine flows. For that, we rely on numerical simulations. High accuracy numerical methods, such as DNS, of wall-bounded flows are very expensive, where the number of grid-points needed to resolve the flow varies as (Re) 9 / 4 (where Re is the flow Reynolds number). While numerically affordable RANS methods compromise on accuracy. Wall-modelled LES methods, which provide both accuracy and affordability, have been improved tremendously in the recent years. We discuss the application of such numerical methods for studying the effect of seabed roughness on marine flow features and their impact on turbine power output and wake characteristics. NSFC, Project Number 11672123.
Straight-Line Target Tracking for Unmanned Surface Vehicles
Directory of Open Access Journals (Sweden)
Morten Breivik
2008-10-01
Full Text Available This paper considers the subject of straight-line target tracking for unmanned surface vehicles (USVs. Target-tracking represents motion control scenarios where no information about the target behavior is known in advance, i.e., the path that the target traverses is not defined apriori. Specifically, this work presents the design of a motion control system which enables an underactuated USV to track a target that moves in a straight line at high speed. The motion control system employs a guidance principle originally developed for interceptor missiles, as well as a novel velocity controller inspired by maneuverability and agility concepts found in fighter aircraft literature. The performance of the suggested design is illustrated through full-scale USV experiments in the Trondheimsfjord.
Three-Axis Ground Reaction Force Distribution during Straight Walking.
Hori, Masataka; Nakai, Akihito; Shimoyama, Isao
2017-10-24
We measured the three-axis ground reaction force (GRF) distribution during straight walking. Small three-axis force sensors composed of rubber and sensor chips were fabricated and calibrated. After sensor calibration, 16 force sensors were attached to the left shoe. The three-axis force distribution during straight walking was measured, and the local features of the three-axis force under the sole of the shoe were analyzed. The heel area played a role in receiving the braking force, the base area of the fourth and fifth toes applied little vertical or shear force, the base area of the second and third toes generated a portion of the propulsive force and received a large vertical force, and the base area of the big toe helped move the body's center of mass to the other foot. The results demonstrate that measuring the three-axis GRF distribution is useful for a detailed analysis of bipedal locomotion.
Aging near the wall in colloidal glasses
Cao, Cong; Huang, Xinru; Weeks, Eric
In a colloidal glass system, particles move slower as sample ages. In addition, their motions may be affected by their local structure, and this structure will be different near a wall. We examine how the aging process near a wall differs from that in the bulk of the sample. In particular, we use a confocal microscope to observe 3D motion in a bidisperse colloidal glass sample. We find that flat walls induce the particles to organize into layers. The aging process behaves differently near the boundary, especially within the first three layers. Particle motion near the wall is noticeably slower but also changes less dramatically with age. We compare and contrast aging seen in samples with flat and rough walls.
Intermediate heat exchanger design study of 25 MW straight-tube hexagonal modular type
International Nuclear Information System (INIS)
Okamoto, Masaharu; Tanaka, Toshiyuki
1983-09-01
The helium-to-helium Intermediate Heat Exchanger(IHX), straight-tube hexagonal modular type was designed at General Atomic Company(GA), which heat duty is 421 MW. For this type IHX, at the selection of basic design, emphasis is placed on cost reduction and size reduction. Then small diameter tube size(11.1 mm), with wall thickness of 1.2 mm is applied to this IHX, necessary for the compact surface geometry. The other side, the helical-tube type IHX was designed at JAERI, which heat duty is 25 MW. This paper discusses the referance design of 25 MW scale IHX, with GA type application. The basic feature of this type IHX is as follows. (1) Thermal stress is reduced, as a result of using small diameter and thin wall thickness tube. (2) The possible improvements can make for higher heat flux, because of short length tube, compare with helical or U-tube type. (3) The simple tube support can use compare with helical or U-tube type. The conclusion reached is that GA type IHX is about one forth compactness and one forth weight compare with helical tube IHX. (author)
Dynamics of one-dimensional domain walls interacting with disorder potential
International Nuclear Information System (INIS)
Krusin-Elbaum, L.; Shibauchi, T.; Argyle, B.; Gignac, L.; Zabel, T.; Weller, D.
2001-01-01
Dynamics of 1D perpendicular-anisotropy domain walls in a few monolayer-thin Co films is imaged by polar Kerr microscopy. When domain walls, driven by a square-pulsed magnetic fields, travel through a random disordered potential landscape, they display Gaussian-distributed roughness characteristic of this landscape. Average velocity of the domain wall driven by a constant magnetic field strongly depends on a strain field which modifies (increases) the elastic energy of the wall and reduces the wall velocity
Rock discontinuity surface roughness variation with scale
Bitenc, Maja; Kieffer, D. Scott; Khoshelham, Kourosh
2017-04-01
ABSTRACT: Rock discontinuity surface roughness refers to local departures of the discontinuity surface from planarity and is an important factor influencing the shear resistance. In practice, the Joint Roughness Coefficient (JRC) roughness parameter is commonly relied upon and input to a shear strength criterion such as developed by Barton and Choubey [1977]. The estimation of roughness by JRC is hindered firstly by the subjective nature of visually comparing the joint profile to the ten standard profiles. Secondly, when correlating the standard JRC values and other objective measures of roughness, the roughness idealization is limited to a 2D profile of 10 cm length. With the advance of measuring technologies that provide accurate and high resolution 3D data of surface topography on different scales, new 3D roughness parameters have been developed. A desirable parameter is one that describes rock surface geometry as well as the direction and scale dependency of roughness. In this research a 3D roughness parameter developed by Grasselli [2001] and adapted by Tatone and Grasselli [2009] is adopted. It characterizes surface topography as the cumulative distribution of local apparent inclination of asperities with respect to the shear strength (analysis) direction. Thus, the 3D roughness parameter describes the roughness amplitude and anisotropy (direction dependency), but does not capture the scale properties. In different studies the roughness scale-dependency has been attributed to data resolution or size of the surface joint (see a summary of researches in [Tatone and Grasselli, 2012]). Clearly, the lower resolution results in lower roughness. On the other hand, have the investigations of surface size effect produced conflicting results. While some studies have shown a decrease in roughness with increasing discontinuity size (negative scale effect), others have shown the existence of positive scale effects, or both positive and negative scale effects. We
Penerapan Metode Straight Selection pada Sistem Parkir Universitas Bina Nusantara
Maharani, Mega; Merlina, Nita
2014-01-01
The parking information System is designed to develop the current system that has been employed at BINA NUSANTARA University. Currently, the parking system is limited only recording the police number and they are still manually looking for the available parking area. The system implements straight selection sorting data method, also known as the smallest number search method to determine the available parking location. Parking area will be automatically printed at parking ticket, thus the dri...
Youth Empowerment and High School Gay-Straight Alliances
Russell, Stephen T.; Muraco, Anna; Subramaniam, Aarti; Laub, Carolyn
2009-01-01
In the field of positive youth development programs, “empowerment” is used interchangeably with youth activism, leadership, civic participation and self-efficacy. However, few studies have captured what empowerment means to young people in diverse contexts. This article explores how youth define and experience empowerment in youth-led organizations characterized by social justice goals: high school Gay-Straight Alliances (GSAs). Through focus group interviews, fifteen youth leaders of GSAs fr...
Propagation of ovalization along straight pipes and elbows
International Nuclear Information System (INIS)
Millard, A.; Roche, R.L.
1981-01-01
The aim of this paper is to present analytical solutions for the propagation of evalization and the variation of the flexibility factor along pipe bends terminated by straight pipes or flanges, under in-plane bending, assuming an elastic material behaviour. The influence of the various strains in analysed in the simple case of a straight pipe, subjected to an elliptical cross-section shape deformation at one end. The results enlighten the very important part played by the distorsion in the propagation. They have been compared with finite elements solutions and with simple experiments. The solution is developed for an elbow terminated by a straight pipe or a flange, following the Von Karman's approach: local displacements are expanded in Fourier series, the coefficients of which vary along the curvilinear abscissa, like the rotation of the cross-section as a whole; the differential equations as well as the boundary conditions are found by minimization of the total potential energy of the assembly. The solutions are compared to existing and experimental results. (orig./HP)
Nonsingular walls in plane cholesteric layers
International Nuclear Information System (INIS)
Belyakov, V A; Osipov, M A; Stewart, I W
2006-01-01
The structure of a straight interface (wall) between regions with differing values of the pitch in planar cholesteric layers with finite strength of the surface anchoring is investigated theoretically. It is found that the shape and strength of the anchoring potential influences essentially the structure of the wall and a motionless wall between thermodynamically stable regions without a singularity in the director distribution in the layer can exist for sufficiently weak anchoring only. More specifically, for the existence of such a wall the dimensionless parameter S d = K 22 /Wd (where W is the depth of the anchoring potential, K 22 is the elastic twist modulus and d is the layer thickness) should exceed its critical value, which is dependent on the shape of the anchoring potential. General equations describing the director distribution in the wall are presented. Detailed analysis of these equations is carried out for the case of infinitely strong anchoring at one surface and finite anchoring strength at the second layer surface. It is shown that the wall width L is directly dependent upon the shape and strength of the anchoring potential and that its estimate ranges from d to (dL p ) 1/2 (where L p = K 22 /W is the penetration length), corresponding to different anchoring strengths and shape potentials. The dependence of the director distribution in the wall upon all three Frank elastic moduli is analytically found for some specific limiting cases of the model anchoring potentials. Motion of the wall is briefly investigated and the corresponding calculations performed under the assumption that the shape of a moving wall is the same as a motionless one. It is noted that experimental investigation of the walls in planar cholesteric layers can be used for the determination of the actual shape of surface anchoring potentials
49 CFR Appendix A to Part 1035 - Uniform Straight Bill of Lading
2010-10-01
... 49 Transportation 8 2010-10-01 2010-10-01 false Uniform Straight Bill of Lading A Appendix A to Part 1035 Transportation Other Regulations Relating to Transportation (Continued) SURFACE... Appendix A to Part 1035—Uniform Straight Bill of Lading Uniform Straight Bill of Lading Original—Not...
26 CFR 1.9001 - Statutory provisions; Retirement-Straight Line Adjustment Act of 1958.
2010-04-01
... 26 Internal Revenue 13 2010-04-01 2010-04-01 false Statutory provisions; Retirement-Straight Line... provisions; Retirement-Straight Line Adjustment Act of 1958. Section 94 of the Technical Amendments Act of 1958 (72 Stat. 1669) provides as follows: Sec. 94. Change from retirement to straight line method of...
21 CFR 70.20 - Packaging requirements for straight colors (other than hair dyes).
2010-04-01
... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Packaging requirements for straight colors (other than hair dyes). 70.20 Section 70.20 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH... straight colors (other than hair dyes). Straight colors shall be packaged in containers which prevent...
26 CFR 7.57(d)-1 - Election with respect to straight line recovery of intangibles.
2010-04-01
... 26 Internal Revenue 14 2010-04-01 2010-04-01 false Election with respect to straight line recovery... ACT OF 1976 § 7.57(d)-1 Election with respect to straight line recovery of intangibles. (a) Purpose... Tax Reform Act of 1976. Under this election taxpayers may use cost depletion to compute straight line...
Bed roughness experiments in supply limited conditions
Spekkers, Matthieu; Tuijnder, Arjan; Ribberink, Jan S.; Hulscher, Suzanne J.M.H.; Parsons, D.R.; Garlan, T.; Best, J.L.
2008-01-01
Reliable roughness models are of great importance, for example, when predicting water levels in rivers. The currently available roughness models are based on fully mobile bed conditions. However, in rivers where widely graded sediments are present more or less permanent armour layers can develop
Axiomatic Characterizations of IVF Rough Approximation Operators
Directory of Open Access Journals (Sweden)
Guangji Yu
2014-01-01
Full Text Available This paper is devoted to the study of axiomatic characterizations of IVF rough approximation operators. IVF approximation spaces are investigated. The fact that different IVF operators satisfy some axioms to guarantee the existence of different types of IVF relations which produce the same operators is proved and then IVF rough approximation operators are characterized by axioms.
Electrochemically grown rough-textured nanowires
International Nuclear Information System (INIS)
Tyagi, Pawan; Postetter, David; Saragnese, Daniel; Papadakis, Stergios J.; Gracias, David H.
2010-01-01
Nanowires with a rough surface texture show unusual electronic, optical, and chemical properties; however, there are only a few existing methods for producing these nanowires. Here, we describe two methods for growing both free standing and lithographically patterned gold (Au) nanowires with a rough surface texture. The first strategy is based on the deposition of nanowires from a silver (Ag)-Au plating solution mixture that precipitates an Ag-Au cyanide complex during electrodeposition at low current densities. This complex disperses in the plating solution, thereby altering the nanowire growth to yield a rough surface texture. These nanowires are mass produced in alumina membranes. The second strategy produces long and rough Au nanowires on lithographically patternable nickel edge templates with corrugations formed by partial etching. These rough nanowires can be easily arrayed and integrated with microscale devices.
Modeling surface roughness scattering in metallic nanowires
Energy Technology Data Exchange (ETDEWEB)
Moors, Kristof, E-mail: kristof@itf.fys.kuleuven.be [KU Leuven, Institute for Theoretical Physics, Celestijnenlaan 200D, B-3001 Leuven (Belgium); IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Sorée, Bart [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Physics Department, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); KU Leuven, Electrical Engineering (ESAT) Department, Kasteelpark Arenberg 10, B-3001 Leuven (Belgium); Magnus, Wim [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Physics Department, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)
2015-09-28
Ando's model provides a rigorous quantum-mechanical framework for electron-surface roughness scattering, based on the detailed roughness structure. We apply this method to metallic nanowires and improve the model introducing surface roughness distribution functions on a finite domain with analytical expressions for the average surface roughness matrix elements. This approach is valid for any roughness size and extends beyond the commonly used Prange-Nee approximation. The resistivity scaling is obtained from the self-consistent relaxation time solution of the Boltzmann transport equation and is compared to Prange-Nee's approach and other known methods. The results show that a substantial drop in resistivity can be obtained for certain diameters by achieving a large momentum gap between Fermi level states with positive and negative momentum in the transport direction.
Suppression of intrinsic roughness in encapsulated graphene
DEFF Research Database (Denmark)
Thomsen, Joachim Dahl; Gunst, Tue; Gregersen, Søren Schou
2017-01-01
Roughness in graphene is known to contribute to scattering effects which lower carrier mobility. Encapsulating graphene in hexagonal boron nitride (hBN) leads to a significant reduction in roughness and has become the de facto standard method for producing high-quality graphene devices. We have...... fabricated graphene samples encapsulated by hBN that are suspended over apertures in a substrate and used noncontact electron diffraction measurements in a transmission electron microscope to measure the roughness of encapsulated graphene inside such structures. We furthermore compare the roughness...... of these samples to suspended bare graphene and suspended graphene on hBN. The suspended heterostructures display a root mean square (rms) roughness down to 12 pm, considerably less than that previously reported for both suspended graphene and graphene on any substrate and identical within experimental error...
Zhang, Qingyan; Jiang, Chunming; Zhu, Wei; Sun, Cheng; Xia, Yangyang; Tang, Tianfeng; Wan, Cheng; Shao, Qiuyuan; Liu, Jing; Jin, Bo; Zhang, Miao
2018-03-01
Catheter malfunction is the main reason for early peritoneal dialysis (PD) technique failure. This study aimed to evaluate the effect of a new surgery technique with catheter fixation to the lower abdominal wall combined with straight upward tunnel and low implant position in reducing catheter malfunction. Patients with end stage renal disease who received PD in our centre from January 2013 to December 2015 were involved in this study. They were randomly divided into three groups according to surgical technique: traditional open surgery group, modified open surgery group and modified open surgery with catheter fixation group. All patients were followed up for six months after surgery. Catheter- related complications were analyzed. A total of 152 patients were involved. Among them, 49 received traditional open surgery (TOS group), 49 received modified open surgery (MOS group), and 54 received modified open surgery with catheter fixation (MOS-F group). During follow-up, no patients (0%) in MOS-F group developed catheter malfunction which was significantly lower than that of the TOS group (0 vs 16.33%, P = 0.002). Although not statistically significant, the incidence of catheter malfunction was lower in MOS-F group than that in MOS group (0 vs 4.08%, P = 0.134). No significant difference was observed in the episodes of infection, bleeding, leakage, inflow or outflow pain, hernia and delayed wound healing among the three groups (all P > 0.05). Catheter fixation combined with straight upward tunnel and low implant position can effectively prevent catheter malfunction in PD catheter placement. © 2016 Asian Pacific Society of Nephrology.
Fingerprinting the type of line edge roughness
Fernández Herrero, A.; Pflüger, M.; Scholze, F.; Soltwisch, V.
2017-06-01
Lamellar gratings are widely used diffractive optical elements and are prototypes of structural elements in integrated electronic circuits. EUV scatterometry is very sensitive to structure details and imperfections, which makes it suitable for the characterization of nanostructured surfaces. As compared to X-ray methods, EUV scattering allows for steeper angles of incidence, which is highly preferable for the investigation of small measurement fields on semiconductor wafers. For the control of the lithographic manufacturing process, a rapid in-line characterization of nanostructures is indispensable. Numerous studies on the determination of regular geometry parameters of lamellar gratings from optical and Extreme Ultraviolet (EUV) scattering also investigated the impact of roughness on the respective results. The challenge is to appropriately model the influence of structure roughness on the diffraction intensities used for the reconstruction of the surface profile. The impact of roughness was already studied analytically but for gratings with a periodic pseudoroughness, because of practical restrictions of the computational domain. Our investigation aims at a better understanding of the scattering caused by line roughness. We designed a set of nine lamellar Si-gratings to be studied by EUV scatterometry. It includes one reference grating with no artificial roughness added, four gratings with a periodic roughness distribution, two with a prevailing line edge roughness (LER) and another two with line width roughness (LWR), and four gratings with a stochastic roughness distribution (two with LER and two with LWR). We show that the type of line roughness has a strong impact on the diffuse scatter angular distribution. Our experimental results are not described well by the present modelling approach based on small, periodically repeated domains.
Magnetization reversal in ferromagnetic spirals via domain wall motion
Schumm, Ryan D.; Kunz, Andrew
2016-11-01
Domain wall dynamics have been investigated in a variety of ferromagnetic nanostructures for potential applications in logic, sensing, and recording. We present a combination of analytic and simulated results describing the reliable field driven motion of a domain wall through the arms of a ferromagnetic spiral nanowire. The spiral geometry is capable of taking advantage of the benefits of both straight and circular wires. Measurements of the in-plane components of the spirals' magnetization can be used to determine the angular location of the domain wall, impacting the magnetoresistive applications dependent on the domain wall location. The spirals' magnetization components are found to depend on the spiral parameters: the initial radius and spacing between spiral arms, along with the domain wall location. The magnetization is independent of the parameters of the rotating field used to move the domain wall, and therefore the model is valid for current induced domain wall motion as well. The speed of the domain wall is found to depend on the frequency of the rotating driving field, and the domain wall speeds can be reliably varied over several orders of magnitude. We further demonstrate a technique capable of injecting multiple domain walls and show the reliable and unidirectional motion of domain walls through the arms of the spiral.
The effect of surface roughness on the heat exchange and pressure-drop coefficients
International Nuclear Information System (INIS)
Malherbe, J.M.
1963-02-01
The effect of various types of roughness on the wall of an axial tube in an annular space of 15-25 mm cooled by an air-flow has been studied in the case of steady turbulence. Roughness of the type 'disrupter of the boundary layer' was set up using triangular threads of 0.2 to 0.4 mm thickness machined in the tube itself, or brass or glass wire wound on a smooth tube. Tests were also carried out using the roughness provided by regularly spaced pyramids 0.4 mm high. The results obtained showed that the heat exchange increased because of the presence of this roughness. A maximum in the heat exchange and pressure-drop coefficients was observed when the pitch equals about eight times the height of the thread. An analytical method has been developed and experiments have been carried out in which the two walls of the annular space were heated in such a way as to transmit unequal heat flows. The region considered is limited to Reynolds's numbers of between 5 X 10 3 and 5 x 10 4 and wall temperatures of under 250 deg C. (author) [fr
Nanoscale roughness effect on Maxwell-like boundary conditions for the Boltzmann equation
Energy Technology Data Exchange (ETDEWEB)
Brull, S., E-mail: Stephane.Brull@math.u-bordeaux.fr; Charrier, P., E-mail: Pierre.Charrier@math.u-bordeaux.fr; Mieussens, L., E-mail: Luc.Mieussens@math.u-bordeaux.fr [University of Bordeaux, CNRS, Bordeaux INP, IMB, UMR 5251, F-33400 Talence (France)
2016-08-15
It is well known that the roughness of the wall has an effect on microscale gas flows. This effect can be shown for large Knudsen numbers by using a numerical solution of the Boltzmann equation. However, when the wall is rough at a nanometric scale, it is necessary to use a very small mesh size which is much too expansive. An alternative approach is to incorporate the roughness effect in the scattering kernel of the boundary condition, such as the Maxwell-like kernel introduced by the authors in a previous paper. Here, we explain how this boundary condition can be implemented in a discrete velocity approximation of the Boltzmann equation. Moreover, the influence of the roughness is shown by computing the structure scattering pattern of mono-energetic beams of the incident gas molecules. The effect of the angle of incidence of these molecules, of their mass, and of the morphology of the wall is investigated and discussed in a simplified two-dimensional configuration. The effect of the azimuthal angle of the incident beams is shown for a three-dimensional configuration. Finally, the case of non-elastic scattering is considered. All these results suggest that our approach is a promising way to incorporate enough physics of gas-surface interaction, at a reasonable computing cost, to improve kinetic simulations of micro- and nano-flows.
The Theory and Assessment of Spatial Straightness Error Matched New Generation GPS
International Nuclear Information System (INIS)
Zhang, X B; Sheng, X L; Jiang, X Q; Li, Z
2006-01-01
In order to assess spatial straightness error matched new generation Dimensional Geometrical Product Specification and Verification (GPS), the theory of spatial straightness error assessing is proposed and its advantages are analyzed based on metrology and statistics in this paper. Then, the assessing parameter system is proposed and it is testified in real application comparing to assessment result of the geometric tolerance theory. Statistical parameters of this assessing system post the different characteristics of spatial straightness error, and can reveal the impact of spatial straightness error on the accessory function more roundly to complement the single assessing parameter of geometrical tolerance for straightness error. The statistical spatial straightness tolerance and statistical spatial straightness error proposed in this paper is possible to be applied in evaluation of other error of form, orientation, location and run-out
Numerical Schemes for Rough Parabolic Equations
Energy Technology Data Exchange (ETDEWEB)
Deya, Aurelien, E-mail: deya@iecn.u-nancy.fr [Universite de Nancy 1, Institut Elie Cartan Nancy (France)
2012-04-15
This paper is devoted to the study of numerical approximation schemes for a class of parabolic equations on (0,1) perturbed by a non-linear rough signal. It is the continuation of Deya (Electron. J. Probab. 16:1489-1518, 2011) and Deya et al. (Probab. Theory Relat. Fields, to appear), where the existence and uniqueness of a solution has been established. The approach combines rough paths methods with standard considerations on discretizing stochastic PDEs. The results apply to a geometric 2-rough path, which covers the case of the multidimensional fractional Brownian motion with Hurst index H>1/3.
Shahmirzadi, Danial; Li, Ronny X; Konofagou, Elisa E
2012-11-01
Pulse wave imaging (PWI) is an ultrasound-based method for noninvasive characterization of arterial stiffness based on pulse wave propagation. Reliable numerical models of pulse wave propagation in normal and pathological aortas could serve as powerful tools for local pulse wave analysis and a guideline for PWI measurements in vivo. The objectives of this paper are to (1) apply a fluid-structure interaction (FSI) simulation of a straight-geometry aorta to confirm the Moens-Korteweg relationship between the pulse wave velocity (PWV) and the wall modulus, and (2) validate the simulation findings against phantom and in vitro results. PWI depicted and tracked the pulse wave propagation along the abdominal wall of canine aorta in vitro in sequential Radio-Frequency (RF) ultrasound frames and estimates the PWV in the imaged wall. The same system was also used to image multiple polyacrylamide phantoms, mimicking the canine measurements as well as modeling softer and stiffer walls. Finally, the model parameters from the canine and phantom studies were used to perform 3D two-way coupled FSI simulations of pulse wave propagation and estimate the PWV. The simulation results were found to correlate well with the corresponding Moens-Korteweg equation. A high linear correlation was also established between PWV² and E measurements using the combined simulation and experimental findings (R² = 0.98) confirming the relationship established by the aforementioned equation.
Visualisation of flow patterns in straight and C-shape thermosyphons
Ong, K. S.; Tshai, K. H.; Firwana, A.
2017-04-01
A heat pipe is a passive heat transfer device capable of transferring a large quantity of heat effectively and efficiently over a long distance and with a small temperature difference between the heat source and heat sink. A heat pipe consists of a metal pipe initially vacuumed and then filled with a small quantity of fluid inside. The pipe is separated into a heating (evaporator) section and a cooling (condenser) section by an adiabatic section. In a run-around-coil heating, ventilation and air conditioning system, a wrap-around heat pipe heat exchanger could be employed to increase dehumidification and to reduce cooling costs. The thermal performance of a thermosyphon is dependent upon type of fill liquid, fill ratio, power input, pipe inclination and pipe dimensions. The boiling and condensation processes that occur inside a thermosyphon are quite complex. During operation, dry-out, burn-out or boiling limit, entrainment or flooding limit and geysering occur. These phenomena would lead to non-uniform axial wall temperature distribution in the pipe, or worse still, ineffective operation. In order to have a better understanding of the internal heat transfer phenomena, a visual study using transparent glass tubes and high speed camera recording of the internal flow patterns would be most helpful. This paper reports on an experimental investigation conducted to visualise the flow patterns in straight and C-shape thermosyphons. The pictures recorded enabled the internal flow boiling and condensation pattern occurring inside a straight and a C-shape thermosyphon to be observed. The thermosyphons were fabricated from 10 mm O/D × 8 mm I/D × 300 mm long glass tubes and filled with water with fill ratios from 0.5 - 1.5. The evaporator sections of the thermosyphons were immersed into a hot water tank that was electrically heated from cold at ambient temperature till boiling. Cooling of the condenser section was achieved using a fan. Preliminary results showed that dry
Straight spinning cosmic strings in Brans-Dicke gravity
Dos Santos, S. Mittmann; da Silva, J. M. Hoff; Cindra, J. L.
2018-03-01
An exact solution of straight spinning cosmic strings in Brans-Dicke theory of gravitation is presented. The possibility of the existence of closed time-like curves around these cosmic strings is analyzed. Furthermore, the stability about the formation of the topological defect discussed here is checked. It is shown that the existence of a suitable choice for the integration constants in which closed time-like curves are not allowed. We also study the (im)possibility of using the obtained spacetime in the rotational curves problem.
The DFBX cryogenic distribution boxes for the LHC straight sections
International Nuclear Information System (INIS)
Zbasnik, Jon P.; Corradi, Carol A.; Green, Michael A.; Kajiyama, Y.; Knolls, Michael J.; LaMantia, Roberto F.; Rasson, Joseph E.; Reavill, Dulie; Turner, William C.
2002-01-01
The DFBX distribution boxes are designed to connect the LHC cryogenic distribution system to the interaction region quadrupoles [1] and dipoles for the Large Hadron Collider (LHC). The DFBX distribution boxes also have the current leads for the superconducting interaction region magnets and the LHC interaction region correction coils. The DFBX boxes also connect the magnet and cryogenic instrumentation to the CERN data collection system. The DFBX boxes serve as the cryogenic circulation center and the nerve center for four of the LHC straight sections. This report describes primarily the cryogenic function of the DFBXs
Gamma-ray streaming in straight pipes and bent ducts
International Nuclear Information System (INIS)
Eid, M.; Diop, C.M.; Nimal, J.C.
1985-04-01
An important shielding problem is the gamma-ray streaming through voids. These problems are encountered in the reactors and reprocessing plants. A Monte Carlo method has been choosed as one of the most powerful technics to solve this kind of problems. Here in that frame, a biasing system which is adapted for two types of geometries is proposed: straight pipes and bent ducts. A code has been written applying this technique. The numerical results obained show the efficiency and the very good economy of the method proposed. It is hoped to extend the method to deal with more complex geometries and polykinetic situation as well
Evaluating the Subjective Straight Ahead Before and After Spaceflight
Campbell, D. J.; Wood, S. J.; Reschke, M. F.; Clement, G.
2017-01-01
This joint European Space Agency (ESA) - NASA study will address adaptive changes in spatial orientation related to the subjective straight ahead and the use of a vibrotactile sensory aid to reduce perceptual errors. The study will be conducted before and after long duration expeditions to the International Space Station (ISS) to examine how spatial processing of target location is altered following exposure to microgravity. This study addresses the sensorimotor research gap to "determine the changes in sensorimotor function over the course of a mission and during recovery after landing."
Secondary Flow Phenomena in Rotating Radial Straight Pipes
Cheng, K. C.; Wang, Liqiu
1995-01-01
Flow visualization results for secondary flow phenomena near the exit of a rotating radial-axis straight pipe (length ࡁ = 82 cm, inside diameter d = 3.81 cm, ࡁ/d 21.52) are presented to study the stabilizing (relaminarization) and destabilizing (early transition from laminar to turbulent flow) effects of Coriolis forces for Reynolds numbers Re = 500 ∼ 4,500 and rotating speeds n = 0 ∼ 200 rpm. The flow visualization was realised by smoke injection method. The main features of the trans...
On the impacts of coarse-scale models of realistic roughness on a forward-facing step turbulent flow
International Nuclear Information System (INIS)
Wu, Yanhua; Ren, Huiying
2013-01-01
Highlights: ► Discrete wavelet transform was used to produce coarse-scale models of roughness. ► PIV were performed in a forward-facing step flow with roughness of different scales. ► Impacts of roughness scales on various turbulence statistics were studied. -- Abstract: The present work explores the impacts of the coarse-scale models of realistic roughness on the turbulent boundary layers over forward-facing steps. The surface topographies of different scale resolutions were obtained from a novel multi-resolution analysis using discrete wavelet transform. PIV measurements are performed in the streamwise–wall-normal (x–y) planes at two different spanwise positions in turbulent boundary layers at Re h = 3450 and δ/h = 8, where h is the mean step height and δ is the incoming boundary layer thickness. It was observed that large-scale but low-amplitude roughness scales had small effects on the forward-facing step turbulent flow. For the higher-resolution model of the roughness, the turbulence characteristics within 2h downstream of the steps are observed to be distinct from those over the original realistic rough step at a measurement position where the roughness profile possesses a positive slope immediately after the step’s front. On the other hand, much smaller differences exist in the flow characteristics at the other measurement position whose roughness profile possesses a negative slope following the step’s front
Spin Hall effect by surface roughness
Zhou, Lingjun; Grigoryan, Vahram L.; Maekawa, Sadamichi; Wang, Xuhui; Xiao, Jiang
2015-01-01
induced by surface roughness subscribes only to the side-jump contribution but not the skew scattering. The paradigm proposed in this paper provides the second, not if only, alternative to generate a sizable spin Hall effect.
Roughness coefficients for stream channels in Arizona
Aldridge, B.N.; Garrett, J.M.
1973-01-01
When water flows in an open channel, energy is lost through friction along the banks and bed of the channel and through turbulence within the channel. The amount of energy lost is governed by channel roughness, which is expressed in terms of a roughness coefficient. An evaluation of the roughness coefficient is necessary in many hydraulic computations that involve flow in an open channel. Owing to the lack of satisfactory quantitative procedure, the ability of evaluate roughness coefficients can be developed only through experience; however, a basic knowledge of the methods used to assign the coefficients and the factors affecting them will be a great help. One of the most commonly used equations in open-channel hydraulics is that of Manning. The Manning equation is 1.486
Investigation on Surface Roughness in Cylindrical Grinding
Rudrapati, Ramesh; Bandyopadhyay, Asish; Pal, Pradip Kumar
2011-01-01
Cylindrical grinding is a complex machining process. And surface roughness is often a key factor in any machining process while considering the machine tool or machining performance. Further, surface roughness is one of the measures of the technological quality of the product and is a factor that greatly influences cost and quality. The present work is related to some aspects of surface finish in the context of traverse-cut cylindrical grinding. The parameters considered have been: infeed, longitudinal feed and work speed. Taguchi quality design is used to design the experiments and to identify the significantly import parameter(s) affecting the surface roughness. By utilization of Response Surface Methodology (RSM), second order differential equation has been developed and attempts have also been made for optimization of the process in the context of surface roughness by using C- programming.
Surface excitation parameter for rough surfaces
International Nuclear Information System (INIS)
Da, Bo; Salma, Khanam; Ji, Hui; Mao, Shifeng; Zhang, Guanghui; Wang, Xiaoping; Ding, Zejun
2015-01-01
Graphical abstract: - Highlights: • Instead of providing a general mathematical model of roughness, we directly use a finite element triangle mesh method to build a fully 3D rough surface from the practical sample. • The surface plasmon excitation can be introduced to the realistic sample surface by dielectric response theory and finite element method. • We found that SEP calculated based on ideal plane surface model are still reliable for real sample surface with common roughness. - Abstract: In order to assess quantitatively the importance of surface excitation effect in surface electron spectroscopy measurement, surface excitation parameter (SEP) has been introduced to describe the surface excitation probability as an average number of surface excitations that electrons can undergo when they move through solid surface either in incoming or outgoing directions. Meanwhile, surface roughness is an inevitable issue in experiments particularly when the sample surface is cleaned with ion beam bombardment. Surface roughness alters not only the electron elastic peak intensity but also the surface excitation intensity. However, almost all of the popular theoretical models for determining SEP are based on ideal plane surface approximation. In order to figure out whether this approximation is efficient or not for SEP calculation and the scope of this assumption, we proposed a new way to determine the SEP for a rough surface by a Monte Carlo simulation of electron scattering process near to a realistic rough surface, which is modeled by a finite element analysis method according to AFM image. The elastic peak intensity is calculated for different electron incident and emission angles. Assuming surface excitations obey the Poisson distribution the SEPs corrected for surface roughness are then obtained by analyzing the elastic peak intensity for several materials and for different incident and emission angles. It is found that the surface roughness only plays an
Small-Scale Surf Zone Geometric Roughness
2017-12-01
using stereo imagery techniques. A waterproof two- camera system with self-logging and internal power was developed using commercial-off-the-shelf...estimates. 14. SUBJECT TERMS surface roughness, nearshore, aerodynamic roughness, surf zone, structure from motion, 3D imagery 15. NUMBER OF... power was developed using commercial-off-the- shelf components and commercial software for operations 1m above the sea surface within the surf zone
How supercontinents and superoceans affect seafloor roughness.
Whittaker, Joanne M; Müller, R Dietmar; Roest, Walter R; Wessel, Paul; Smith, Walter H F
2008-12-18
Seafloor roughness varies considerably across the world's ocean basins and is fundamental to controlling the circulation and mixing of heat in the ocean and dissipating eddy kinetic energy. Models derived from analyses of active mid-ocean ridges suggest that ocean floor roughness depends on seafloor spreading rates, with rougher basement forming below a half-spreading rate threshold of 30-35 mm yr(-1) (refs 4, 5), as well as on the local interaction of mid-ocean ridges with mantle plumes or cold-spots. Here we present a global analysis of marine gravity-derived roughness, sediment thickness, seafloor isochrons and palaeo-spreading rates of Cretaceous to Cenozoic ridge flanks. Our analysis reveals that, after eliminating effects related to spreading rate and sediment thickness, residual roughness anomalies of 5-20 mGal remain over large swaths of ocean floor. We found that the roughness as a function of palaeo-spreading directions and isochron orientations indicates that most of the observed excess roughness is not related to spreading obliquity, as this effect is restricted to relatively rare occurrences of very high obliquity angles (>45 degrees ). Cretaceous Atlantic ocean floor, formed over mantle previously overlain by the Pangaea supercontinent, displays anomalously low roughness away from mantle plumes and is independent of spreading rates. We attribute this observation to a sub-Pangaean supercontinental mantle temperature anomaly leading to slightly thicker than normal Late Jurassic and Cretaceous Atlantic crust, reduced brittle fracturing and smoother basement relief. In contrast, ocean crust formed above Pacific superswells, probably reflecting metasomatized lithosphere underlain by mantle at only slightly elevated temperatures, is not associated with basement roughness anomalies. These results highlight a fundamental difference in the nature of large-scale mantle upwellings below supercontinents and superoceans, and their impact on oceanic crustal
Role of surface roughness in superlubricity
International Nuclear Information System (INIS)
Tartaglino, U; Samoilov, V N; Persson, B N J
2006-01-01
We study the sliding of elastic solids in adhesive contact with flat and rough interfaces. We consider the dependence of the sliding friction on the elastic modulus of the solids. For elastically hard solids with planar surfaces with incommensurate surface structures we observe extremely low friction (superlubricity), which very abruptly increases as the elastic modulus decreases. We show that even a relatively small surface roughness may completely kill the superlubricity state
Safeguards and security benefits of project straight-line
International Nuclear Information System (INIS)
Jaeger, C.D.; Waddoups, I.G.
1995-01-01
As a result of a number of events the inventory of fissile materials no longer in nuclear weapons in the United States is increasing. This has led to a growing concern regarding the potential for theft and/or diversion and accountability of this material. Straight-Line is a project whose purpose is to demonstrate a site-independent system to monitor stored nuclear material (e.g. plutonium) and integrate the collection, processing and dissemination of information regarding this material. Safeguards and security (S ampersand S) goals of this project include data transfer of information on nuclear material to appropriate users to enhance S ampersand S, continuous on-line accountability, reduction of hands-on access to nuclear materials, incorporation of information security technologies, and early detection of tampering or unauthorized material movement. This paper addresses threat considerations, S ampersand S requirements, S ampersand S objectives, and issues for the Straight-Line project. S ampersand S features and benefits of this project are discussed with respect to existing item monitoring systems and/or other material tracking systems being developed
Excessive deformation and failure of straight parts and elbows
International Nuclear Information System (INIS)
Touboul, F.; Acker, D.
1991-01-01
The design rules for LMFBRs must cover the ranges of loading types and geometries wider than PWR Design Codes. Steam pipework does not differ between two reactor systems, but as far as sodium piping is concerned, usual PWR criteria may not be adequate. The LMFBR sodium piping is operated at high temperature and low pressure level. Moreover, these peculiar loadings require the geometrical characteristics completely different in the fact that the piping must be flexible but need not to be thick. For such piping components, the ultimate behavior depends much on the geometry. 170 experimental results on straight parts and 95 results on elbows were investigated. As for elbows, half of the tests were performed under in-plane closing moment. On the analysis of straight pipes and elbows, the experiments and the proposed expressions for the evaluation of collapse and instability moments are described, respectively. The application of the present study to the design rules and the criteria for various loading conditions are reported. It is difficult to experimentally distinguish between plastic instability and buckling. (K.I.)
An in-situ measuring method for planar straightness error
Chen, Xi; Fu, Luhua; Yang, Tongyu; Sun, Changku; Wang, Zhong; Zhao, Yan; Liu, Changjie
2018-01-01
According to some current problems in the course of measuring the plane shape error of workpiece, an in-situ measuring method based on laser triangulation is presented in this paper. The method avoids the inefficiency of traditional methods like knife straightedge as well as the time and cost requirements of coordinate measuring machine(CMM). A laser-based measuring head is designed and installed on the spindle of a numerical control(NC) machine. The measuring head moves in the path planning to measure measuring points. The spatial coordinates of the measuring points are obtained by the combination of the laser triangulation displacement sensor and the coordinate system of the NC machine, which could make the indicators of measurement come true. The method to evaluate planar straightness error adopts particle swarm optimization(PSO). To verify the feasibility and accuracy of the measuring method, simulation experiments were implemented with a CMM. Comparing the measurement results of measuring head with the corresponding measured values obtained by composite measuring machine, it is verified that the method can realize high-precise and automatic measurement of the planar straightness error of the workpiece.
Numerical modelling of flow and transport in rough fractures
Directory of Open Access Journals (Sweden)
Scott Briggs
2014-12-01
Full Text Available Simulation of flow and transport through rough walled rock fractures is investigated using the lattice Boltzmann method (LBM and random walk (RW, respectively. The numerical implementation is developed and validated on general purpose graphic processing units (GPGPUs. Both the LBM and RW method are well suited to parallel implementation on GPGPUs because they require only next-neighbour communication and thus can reduce expenses. The LBM model is an order of magnitude faster on GPGPUs than published results for LBM simulations run on modern CPUs. The fluid model is verified for parallel plate flow, backward facing step and single fracture flow; and the RW model is verified for point-source diffusion, Taylor-Aris dispersion and breakthrough behaviour in a single fracture. Both algorithms place limitations on the discrete displacement of fluid or particle transport per time step to minimise the numerical error that must be considered during implementation.
International Nuclear Information System (INIS)
Omori, Junji.
1991-01-01
Graphite and C/C composite are used recently for the first wall of a thermonuclear device since materials with small atom number have great impurity allowable capacity for plasmas. Among them, those materials having high thermal conduction are generally anisotropic and have an upper limit for the thickness upon production. Then, anisotropic materials are used for a heat receiving plate, such that the surfaces of the heat receiving plate on the side of lower heat conductivity are brought into contact with each other, and the side of higher thermal conductivity is arranged in parallel with small radius direction and the toroidal direction of the thermonuclear device. As a result, the incident heat on an edge portion can be transferred rapidly to the heat receiving plate, which can suppress the temperature elevation at the surface to thereby reduce the amount of abrasion. Since the heat expansion coefficient of the anisotropic materials is great in the direction of the lower heat conductivity and small in the direction of the higher heat conductivity, the gradient of a thermal load distribution in the direction of the higher heat expansion coefficient is small, and occurrence of thermal stresses due to temperature difference is reduced, to improve the reliability. (N.H.)
It was 20 years ago this week that the Berlin wall was opened for the first time since its construction began in 1961. Although the signs of a thaw had been in the air for some time, few predicted the speed of the change that would ensue. As members of the scientific community, we can take a moment to reflect on the role our field played in bringing East and West together. CERN’s collaboration with the East, primarily through links with the Joint Institute for Nuclear Research, JINR, in Dubna, Russia, is well documented. Less well known, however, is the role CERN played in bringing the scientists of East and West Germany together. As the Iron curtain was going up, particle physicists on both sides were already creating the conditions that would allow it to be torn down. Cold war historian Thomas Stange tells the story in his 2002 CERN Courier article. It was my privilege to be in Berlin on Monday, the anniversary of the wall’s opening, to take part in a conference entitled &lsquo...
Dissolution of minerals with rough surfaces
de Assis, Thiago A.; Aarão Reis, Fábio D. A.
2018-05-01
We study dissolution of minerals with initial rough surfaces using kinetic Monte Carlo simulations and a scaling approach. We consider a simple cubic lattice structure, a thermally activated rate of detachment of a molecule (site), and rough surface configurations produced by fractional Brownian motion algorithm. First we revisit the problem of dissolution of initial flat surfaces, in which the dissolution rate rF reaches an approximately constant value at short times and is controlled by detachment of step edge sites. For initial rough surfaces, the dissolution rate r at short times is much larger than rF ; after dissolution of some hundreds of molecular layers, r decreases by some orders of magnitude across several time decades. Meanwhile, the surface evolves through configurations of decreasing energy, beginning with dissolution of isolated sites, then formation of terraces with disordered boundaries, their growth, and final smoothing. A crossover time to a smooth configuration is defined when r = 1.5rF ; the surface retreat at the crossover is approximately 3 times the initial roughness and is temperature-independent, while the crossover time is proportional to the initial roughness and is controlled by step-edge site detachment. The initial dissolution process is described by the so-called rough rates, which are measured for fixed ratios between the surface retreat and the initial roughness. The temperature dependence of the rough rates indicates control by kink site detachment; in general, it suggests that rough rates are controlled by the weakest microscopic bonds during the nucleation and formation of the lowest energy configurations of the crystalline surface. Our results are related to recent laboratory studies which show enhanced dissolution in polished calcite surfaces. In the application to calcite dissolution in alkaline environment, the minimal values of recently measured dissolution rate spectra give rF ∼10-9 mol/(m2 s), and the calculated rate
Rough mill simulator version 3.0: an analysis tool for refining rough mill operations
Edward Thomas; Joel Weiss
2006-01-01
ROMI-3 is a rough mill computer simulation package designed to be used by both rip-first and chop-first rough mill operators and researchers. ROMI-3 allows users to model and examine the complex relationships among cutting bill, lumber grade mix, processing options, and their impact on rough mill yield and efficiency. Integrated into the ROMI-3 software is a new least-...
Rebstock, Rainer; Lee, Edwin E., Jr.
1989-01-01
An initial wind tunnel test was made to validate a new wall adaptation method for 3-D models in test sections with two adaptive walls. First part of the adaptation strategy is an on-line assessment of wall interference at the model position. The wall induced blockage was very small at all test conditions. Lift interference occurred at higher angles of attack with the walls set aerodynamically straight. The adaptation of the top and bottom tunnel walls is aimed at achieving a correctable flow condition. The blockage was virtually zero throughout the wing planform after the wall adjustment. The lift curve measured with the walls adapted agreed very well with interference free data for Mach 0.7, regardless of the vertical position of the wing in the test section. The 2-D wall adaptation can significantly improve the correctability of 3-D model data. Nevertheless, residual spanwise variations of wall interference are inevitable.
FLOW PHYSICS OF 3-BLADED STRAIGHT CHORD H-DARRIEUS WIND TURBINE
Directory of Open Access Journals (Sweden)
Rajat Gupta
2013-06-01
Full Text Available Steady-state two-dimensional Computational Fluid Dynamics (CFD simulations were performed using Fluent 6.0 software to analyze the flow physics of 3-bladed straight chord H-Darrieus wind turbine having blade twist of 300 for 10% of its chord at the trailing ends. The flow was simulated using finite volume method coupled with moving mesh technique to solve mass and momentum conservation equations. The standard k-ε turbulence model with enhanced wall condition was used. Second-order upwind discretization scheme was adopted for pressure-velocity coupling of the flow. Flow physics of the turbine was analyzed with the help of pressure and velocity contours. It was found that velocity magnitude decreases from upstream to downstream side across the turbine, which will cause overall lift for the turbine. Further, blade twist at the trailing ends creates circulations that interact with the blades in a direction opposite to the direction of rotation of the turbine which would enhance power production for the three bladed turbine.
FLOW PHYSICS OF 3-BLADED STRAIGHT CHORD H- DARRIEUS WIND TURBINE
Directory of Open Access Journals (Sweden)
Rajat Gupta
2013-01-01
Full Text Available Steady-state two-dimensional Computational Fluid Dynamics (CFD simulations were performed using Fluent 6.0 software to analyze the flow physics of 3-bladed straight chord H-Darrieus wind turbine having blade twist of 300 for 10% of its chord at the trailing ends. The flow was simulated using finite volume method coupled with moving mesh technique to solve mass and momentum conservation equations. The standard k- ε turbulence model with enhanced wall condition was used. Second-order upwind discretization scheme was adopted for pressure-velocity coupling of the flow. Flow physics of the turbine was analyzed with the help of pressure and velocity contours. It was found that velocity magnitude decreases from upstream to downstream side across the turbine, which will cause overall lift for the turbine. Further, blade twist at the trailing ends creates circulations that interact with the blades in a direction opposite to the direction of rotation of the turbine which would enhance power production for the three bladed turbine.
Registration of airborne LiDAR data and aerial images based on straight lines and POS data
Du, Quanye; Xu, Biao; Cao, Hui
2009-10-01
This paper presents a registration method which based on straight lines primitive. Firstly, 2D straight lines are extracted from aerial images using Canny operator and straight line fitting. In the similar way, 3D straight lines are extracted from LiDAR range images which derive from laser scanning point cloud. Secondly, 3D straight lines are projected to aerial images using collinearity equations and Position and Orientation System (POS) data. Then the corresponding lines are determined by straight line error. At last, each image's new exterior orientation elements are calculated by generalized point (straight line) photogrammetry.
Yang, Xiang I. A.; Meneveau, Charles
2016-01-01
The technique by Lund et al. to generate turbulent inflow for simulations of developing boundary layers over smooth flat plates is extended to the case of surfaces with roughness elements. In the Lund et al. method, turbulent velocities on a sampling plane are rescaled and recycled back to the inlet as inflow boundary condition. To rescale mean and fluctuating velocities, appropriate length scales need be identified and for smooth surfaces, the viscous scale lν = ν/uτ (where ν is the kinematic viscosity and uτ is the friction velocity) is employed for the inner layer. Different from smooth surfaces, in rough wall boundary layers the length scale of the inner layer, i.e. the roughness sub-layer scale ld, must be determined by the geometric details of the surface roughness elements and the flow around them. In the proposed approach, it is determined by diagnosing dispersive stresses that quantify the spatial inhomogeneity caused by the roughness elements in the flow. The scale ld is used for rescaling in the inner layer, and the boundary layer thickness δ is used in the outer region. Both parts are then combined for recycling using a blending function. Unlike the blending function proposed by Lund et al. which transitions from the inner layer to the outer layer at approximately 0.2δ, here the location of blending is shifted upwards to enable simulations of very rough surfaces in which the roughness length may exceed the height of 0.2δ assumed in the traditional method. The extended rescaling-recycling method is tested in large eddy simulation of flow over surfaces with various types of roughness element shapes.
Energy Technology Data Exchange (ETDEWEB)
Charles, T.K. [School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800 (Australia); Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria, 3168 (Australia); Paganin, D.M. [School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800 (Australia); Dowd, R.T. [Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria, 3168 (Australia)
2016-08-21
Intrinsic emittance is often the limiting factor for brightness in fourth generation light sources and as such, a good understanding of the factors affecting intrinsic emittance is essential in order to be able to decrease it. Here we present a parameterization model describing the proportional increase in emittance induced by cathode surface roughness. One major benefit behind the parameterization approach presented here is that it takes the complexity of a Monte Carlo model and reduces the results to a straight-forward empirical model. The resulting models describe the proportional increase in transverse momentum introduced by surface roughness, and are applicable to various metal types, photon wavelengths, applied electric fields, and cathode surface terrains. The analysis includes the increase in emittance due to changes in the electric field induced by roughness as well as the increase in transverse momentum resultant from the spatially varying surface normal. We also compare the results of the Parameterization Model to an Analytical Model which employs various approximations to produce a more compact expression with the cost of a reduction in accuracy.
Prediction of the surface roughness of AA6082 flow-formed tubes by design of experiments
International Nuclear Information System (INIS)
Srinivasulu, M.; Komaraiah, M.; Rao, C. S. Krishna Prasada
2013-01-01
Flow forming is a modern, chipless metal forming process that is employed for the production of thin-walled seamless tubes. Experiments are conducted on AA6082 alloy pre-forms to flow form into thin-walled tubes on a CNC flow-forming machine with a single roller. Design of experiments is used to predict the surface roughness of flow-formed tubes. The process parameters selected for this study are the roller axial feed, mandrel speed, and roller radius. A standard response surface methodology (RSM) called the Box Behnken design is used to perform the experimental runs. The regression model developed by RSM successfully predicts the surface roughness of AA6082 flow-formed tubes within the range of the selected process parameters.
Prediction of the surface roughness of AA6082 flow-formed tubes by design of experiments
Energy Technology Data Exchange (ETDEWEB)
Srinivasulu, M. [Government Polytechnic for Women Badangpet, Hyderabad (India); Komaraiah, M. [Sreenidhi Institute of Science and Technology, Hyderabad (India); Rao, C. S. Krishna Prasada [Bharat Dynamics Limited, Hyderabad (India)
2013-06-15
Flow forming is a modern, chipless metal forming process that is employed for the production of thin-walled seamless tubes. Experiments are conducted on AA6082 alloy pre-forms to flow form into thin-walled tubes on a CNC flow-forming machine with a single roller. Design of experiments is used to predict the surface roughness of flow-formed tubes. The process parameters selected for this study are the roller axial feed, mandrel speed, and roller radius. A standard response surface methodology (RSM) called the Box Behnken design is used to perform the experimental runs. The regression model developed by RSM successfully predicts the surface roughness of AA6082 flow-formed tubes within the range of the selected process parameters.
Mitigating mask roughness via pupil filtering
Baylav, B.; Maloney, C.; Levinson, Z.; Bekaert, J.; Vaglio Pret, A.; Smith, B.
2014-03-01
The roughness present on the sidewalls of lithographically defined patterns imposes a very important challenge for advanced technology nodes. It can originate from the aerial image or the photoresist chemistry/processing [1]. The latter remains to be the dominant group in ArF and KrF lithography; however, the roughness originating from the mask transferred to the aerial image is gaining more attention [2-9], especially for the imaging conditions with large mask error enhancement factor (MEEF) values. The mask roughness contribution is usually in the low frequency range, which is particularly detrimental to the device performance by causing variations in electrical device parameters on the same chip [10-12]. This paper explains characteristic differences between pupil plane filtering in amplitude and in phase for the purpose of mitigating mask roughness transfer under interference-like lithography imaging conditions, where onedirectional periodic features are to be printed by partially coherent sources. A white noise edge roughness was used to perturbate the mask features for validating the mitigation.
Development of nano-roughness calibration standards
International Nuclear Information System (INIS)
Baršić, Gorana; Mahović, Sanjin; Zorc, Hrvoje
2012-01-01
At the Laboratory for Precise Measurements of Length, currently the Croatian National Laboratory for Length, unique nano-roughness calibration standards were developed, which have been physically implemented in cooperation with the company MikroMasch Trading OU and the Ruđer Bošković Institute. In this paper, a new design for a calibration standard with two measuring surfaces is presented. One of the surfaces is for the reproduction of roughness parameters, while the other is for the traceability of length units below 50 nm. The nominal values of the groove depths on these measuring surfaces are the same. Thus, a link between the measuring surfaces has been ensured, which makes these standards unique. Furthermore, the calibration standards available on the market are generally designed specifically for individual groups of measuring instrumentation, such as interferometric microscopes, stylus instruments, scanning electron microscopes (SEM) or scanning probe microscopes. In this paper, a new design for nano-roughness standards has been proposed for use in the calibration of optical instruments, as well as for stylus instruments, SEM, atomic force microscopes and scanning tunneling microscopes. Therefore, the development of these new nano-roughness calibration standards greatly contributes to the reproducibility of the results of groove depth measurement as well as the 2D and 3D roughness parameters obtained by various measuring methods. (paper)
A Rough Set Approach for Customer Segmentation
Directory of Open Access Journals (Sweden)
Prabha Dhandayudam
2014-04-01
Full Text Available Customer segmentation is a process that divides a business's total customers into groups according to their diversity of purchasing behavior and characteristics. The data mining clustering technique can be used to accomplish this customer segmentation. This technique clusters the customers in such a way that the customers in one group behave similarly when compared to the customers in other groups. The customer related data are categorical in nature. However, the clustering algorithms for categorical data are few and are unable to handle uncertainty. Rough set theory (RST is a mathematical approach that handles uncertainty and is capable of discovering knowledge from a database. This paper proposes a new clustering technique called MADO (Minimum Average Dissimilarity between Objects for categorical data based on elements of RST. The proposed algorithm is compared with other RST based clustering algorithms, such as MMR (Min-Min Roughness, MMeR (Min Mean Roughness, SDR (Standard Deviation Roughness, SSDR (Standard deviation of Standard Deviation Roughness, and MADE (Maximal Attributes DEpendency. The results show that for the real customer data considered, the MADO algorithm achieves clusters with higher cohesion, lower coupling, and less computational complexity when compared to the above mentioned algorithms. The proposed algorithm has also been tested on a synthetic data set to prove that it is also suitable for high dimensional data.
Energy Technology Data Exchange (ETDEWEB)
Sohn, Hyun Chull [Chosun Univ., Gwangju (Korea, Republic of)
2005-05-01
In the present study, the characteristics of developing steady laminar flows of a straight duct connected to a 180 .deg. curved duct were examined in the entrance region through experimental measurement. Flow characteristics such as shear stress distributions, pressure distributions and friction coefficient experimentally in a square cross-sectional straight duct by using the PIV system. For the PIV measurement by particles produced from mosquito coils particles. The experimental data were obtained at 9 points dividing the test sections by 400 mm. Experimental results can be summarized as follows. Critical Reynolds number, Re{sub cr} which indicates transition from laminar steady flow to transition steady flow was 2,150. Shear stress per unit length on the wall was stronger than that in the fully developed flow region. This was attributed to the fact that shear stress and pressure loss in the curvature of a duct were increased. Pressure distributions were gradually decreased irrespective of Reynolds number in the whole test section. This trends were in a good agreement with the reference results. Pipe friction coefficient in the steady state flow region was calculate from method of least squares. The co-relationship between fiction coefficient and Reynolds number was established as follow; {lambda}=56/Re.
Straight-bladed Darrieus wind turbines - A protagonist's view
Migliore, P. G.
The technology development and market penetration of Darrieus and propeller-type wind turbines is addressed. Important characteristics of competing configurations are compared, and it is claimed that aerodynamic efficiency is not a distinguishing feature. Advantages of the Darrieus machine include omni-directionality and self-limitation, but propeller types require less rotor length per unit swept area. It is argued that the straight-bladed Darrieus is much simpler than the curved-bladed and should be capable of comparable aerodynamic efficiency. Some of the problems of structural design, as well as blade induced drag losses and support-arm counter torque, diminish rapidly as machine size is increased. Taper ratio has similar beneficial effects.
UHV testing of spare straight section chambers of Indus-2
International Nuclear Information System (INIS)
Tiwari, S.K.; Ratnakala, K.C.; Sridhar, R.; Bhange, N.J.; Netram; Shukla, S.K.
2015-01-01
The vacuum system of Synchrotron Radiation Source, Indus-2, in RRCAT has been functioning up to the mark, continuously for last 10 years. To continue the same trouble-free functioning, it was planned to procure spares for all critical vacuum components, test for UHV performance and keep ready for installation, in case of requirement. As a part of this planning, fifteen chambers made of Aluminium alloy (6063 T6), procured as spare straight section chambers for Indus-2, and were tested for UHV performance. They were tested in batches of 2 or 3 chambers, depending upon their length, and the similar testing-procedure was followed. This paper narrates the tests carried out, and the results obtained. Ultimate vacuum in the range (2 to 9) x 10 -10 mbar was achieved. (author)
Structural damping results from vibration tests of straight piping sections
International Nuclear Information System (INIS)
Ware, A.G.; Thinnes, G.L.
1984-01-01
EG and G Idaho is assisting the USNRC and the Pressure Vessel Research Committee in supporting a final position on revised damping values for structural analyses of nuclear piping systems. As part of this program, a series of vibrational tests on 76-mm and 203-mm (3-in. amd 8-in.) Schedule 40 carbon steel piping was conducted to determine the changes in structural damping due to various parametric effects. The 10-m (33-ft) straight sections of piping were rigidly supported at the ends. Spring, rod, and constant force hangers, as well as a sway brace and snubbers were included as intermediate supports. Excitation was provided by low-force level hammer inpacts, a hydraulic shaker, and a 445-kN (50-ton) overhead crane. Data was recorded using acceleration, strain, and displacement time histories. This paper presents results from the testing showing the effect of stress level and type of supports on structural damping in piping
Plastic anisotropy of straight and cross rolled molybdenum sheets
International Nuclear Information System (INIS)
Oertel, C.-G.; Huensche, I.; Skrotzki, W.; Knabl, W.; Lorich, A.; Resch, J.
2008-01-01
The microstructure, texture and mechanical properties of molybdenum sheets produced by different rolling processes were investigated by orientation imaging in the scanning electron microscope, X-ray diffraction and tensile tests, respectively. For comparable recrystallization degree of the sheets investigated, straight rolling with low reduction ratio produces α-fiber textures with a maximum at {100} . At higher rolling degrees the maximum shifts to {112} . Cross rolling increases the rotated cube component {100} . The strong differences in the texture measured are reflected in the plastic anisotropy characterized by differences in the yield stress and Lankford parameter which were measured along directions in the rolling plane at angles of 0 deg., 45 deg. and 90 deg. with the rolling direction. The Taylor-Bishop-Hill theory is used successfully to qualitatively explain the plastic anisotropy
Lateral convection and diffusion of sediment in straight rivers
DEFF Research Database (Denmark)
Christensen, Henrik Bo; Fredsøe, Jørgen
1998-01-01
and a higher level of turbulence at the channel centre, than in the near bank zones, which means that the ability to support suspended sediment will decrease from the channel centre. The two turbulence models give different estimates for the lateral transport, which mainly are caused by turbulence generated......The lateral transport of suspended sediment in a straight river cross section with a parabolic shaped bed is studied be use of a k-e and a full Reynolds stress turbulence model. Due to depth variations a lateral transport of suspended sediment is generated. This is mainly caused by the slopping bed...... secondary flow cells in the Reynolds stress model. The flow cells make zones with alternately high and low sediment concentration, and thereby much higher local gradients in the lateral direction. Both models found a net inward lateral transport. The transport by convection was found more dominant than...
Thermal Performance of the LHC Short Straight Section Cryostat
Bergot, J B; Nielsen, L; Parma, Vittorio; Rohmig, P; Roy, E
2002-01-01
The LHC Short Straight Section (SSS) cryostat houses and thermally protects in vacuum the cold mass which contains a twin-aperture superconducting quadrupole magnet and superconducting corrector magnets operating at 1.9 K in superfluid helium. In addition to mechanical requirements, the cryostat is designed to minimize the heat in-leak from the ambient temperature to the cold mass. Mechanical components linking the cold mass to the vacuum vessel such as support posts and an insulation vacuum barrier are designed to have minimum heat conductivity with efficient thermalisations for heat interception. Heat in-leak by radiation is reduced by employing multilayer insulation wrapped around the cold mass and an actively cooled aluminium thermal shield. The recent commissioning and operation of two SSS prototypes in the LHC Test String 2 have given a first experimental validation of the thermal performance of the SSS cryostat in nominal operating conditions. Temperature sensors mounted in critical locations provide a...
Spin Hall effect by surface roughness
Zhou, Lingjun
2015-01-08
The spin Hall and its inverse effects, driven by the spin orbit interaction, provide an interconversion mechanism between spin and charge currents. Since the spin Hall effect generates and manipulates spin current electrically, to achieve a large effect is becoming an important topic in both academia and industries. So far, materials with heavy elements carrying a strong spin orbit interaction, provide the only option. We propose here a new mechanism, using the surface roughness in ultrathin films, to enhance the spin Hall effect without heavy elements. Our analysis based on Cu and Al thin films suggests that surface roughness is capable of driving a spin Hall angle that is comparable to that in bulk Au. We also demonstrate that the spin Hall effect induced by surface roughness subscribes only to the side-jump contribution but not the skew scattering. The paradigm proposed in this paper provides the second, not if only, alternative to generate a sizable spin Hall effect.
Why do rough surfaces appear glossy?
Qi, Lin; Chantler, Mike J; Siebert, J Paul; Dong, Junyu
2014-05-01
The majority of work on the perception of gloss has been performed using smooth surfaces (e.g., spheres). Previous studies that have employed more complex surfaces reported that increasing mesoscale roughness increases perceived gloss [Psychol. Sci.19, 196 (2008), J. Vis.10(9), 13 (2010), Curr. Biol.22, 1909 (2012)]. We show that the use of realistic rendering conditions is important and that, in contrast to [Psychol. Sci.19, 196 (2008), J. Vis.10(9), 13 (2010)], after a certain point increasing roughness further actually reduces glossiness. We investigate five image statistics of estimated highlights and show that for our stimuli, one in particular, which we term "percentage of highlight area," is highly correlated with perceived gloss. We investigate a simple model that explains the unimodal, nonmonotonic relationship between mesoscale roughness and percentage highlight area.
Exact solution for flow in a porous pipe with unsteady wall suction and/or injection
Tsangaris, S.; Kondaxakis, D.; Vlachakis, N. W.
2007-10-01
This paper presents an extension of the exact solution of the steady laminar axisymmetric flow in a straight pipe of circular cross section with porous wall, given by R.M. Terrill, to the case of unsteady wall injection and/or suction. The cases of the pulsating parabolic profile and of the developed pulsating flow are investigated as examples. The pulsating flow in porous ducts has many applications in biomedical engineering and in other engineering areas.
Analytic solutions of del x B = αB in a straight cylinder with α = α(r)
International Nuclear Information System (INIS)
Ling, K.M.; Baker, D.A.
1985-06-01
Analytic solutions of del x B = αB are presented for reversed field pinch (RFP) configurations in a straight cylinder with α = α(r) where r is the radial coordinate. The function α(r) is a smooth function of r vanishing at the wall (r = a). Closed form parametric formulas for a family of F-THETA curves are obtained from the analytic, cylindrically symmetric, force-free fields. These formulas can be used to fit experimental F-THETA curves and hence facilitate comparison between the various existing RFP experiments. The advantage of these formulas lies in the fact that they are expressed in terms of easily obtainable Bessel functions of the first kind, eliminating the need of mumerical integration. Results of the least-square fits of two typical ZT-40M shots are presented
International Nuclear Information System (INIS)
Tsukamoto, Kunihiro; Yamamoto, Morikuni; Naruoka, Masayoshi; Matsubara, Takayuki
2004-01-01
Ooma nuclear power plant is going to build the exclusive harbors, of which west breakwater is a double slits type straight caisson bank (double slits caisson). It contains double transmission walls and retarding rooms, which show large effect of breaker, because the reflected wave height of short-period component is decreased in the rear retarding room and one of long-period component decreased in both retarding rooms. Accordingly, it is seemed to be proved larger effect of breaker than one slit type caisson. Outline of harbors construction, adoption of double slits caisson, design of caisson, construction of caisson and installation are stated. The effect of breaker of double slits caisson is shown. (S.Y.)
International Nuclear Information System (INIS)
Ludewig, H.; Catalan-Lasheras, N.; Simos, N.; Walker, J.; Mallen, A.; Wei, J.; Todosow, M.
2000-01-01
The highest doses to components in the SNS ring are expected to be to those located in the collimation straight section. In this paper the authors present estimated doses to magnets and cable located between collimators. In addition the buildup of relatively long half-life radioactive isotopes is estimated, following machine operation and shutdown. Finally, the potential dose to operators approaching the machine following operation and shutdown for four hours is made. The results indicate that selected components might require replacement after several years of full power operation. In addition, the reflection of gamma-rays from the tunnel walls contribute a non-negligible amount to the dose of an operator in the tunnel following machine shutdown
Suiker, A.S.J.
2018-01-01
In the current contribution for the first time a mechanistic model is presented that can be used for analysing and optimising the mechanical performance of straight wall structures in 3D printing processes. The two failure mechanisms considered are elastic buckling and plastic collapse. The model
Water hammer with fluid-structure interaction in thick-walled pipes
Tijsseling, A.S.
2007-01-01
A one-dimensional mathematical model is presented which describes the acoustic behaviour of thick-walled liquid-filled pipes. The model is based on conventional water-hammer and beam theories. Fluid–structure interaction (FSI) is taken into account. The equations governing straight pipes are derived
Fuzzy sets, rough sets, multisets and clustering
Dahlbom, Anders; Narukawa, Yasuo
2017-01-01
This book is dedicated to Prof. Sadaaki Miyamoto and presents cutting-edge papers in some of the areas in which he contributed. Bringing together contributions by leading researchers in the field, it concretely addresses clustering, multisets, rough sets and fuzzy sets, as well as their applications in areas such as decision-making. The book is divided in four parts, the first of which focuses on clustering and classification. The second part puts the spotlight on multisets, bags, fuzzy bags and other fuzzy extensions, while the third deals with rough sets. Rounding out the coverage, the last part explores fuzzy sets and decision-making.
Diffuse neutron scattering signatures of rough films
International Nuclear Information System (INIS)
Pynn, R.; Lujan, M. Jr.
1992-01-01
Patterns of diffuse neutron scattering from thin films are calculated from a perturbation expansion based on the distorted-wave Born approximation. Diffuse fringes can be categorised into three types: those that occur at constant values of the incident or scattered neutron wavevectors, and those for which the neutron wavevector transfer perpendicular to the film is constant. The variation of intensity along these fringes can be used to deduce the spectrum of surface roughness for the film and the degree of correlation between the film's rough surfaces
Aghaei Jouybari, Mostafa; Yuan, Junlin
2017-11-01
Direct numerical simulations of turbulent channel flows are carried out over two surfaces: a synthesized sand-grain surface and a realistic turbine roughness that is characterized by more prominent large-scale surface features. To separate the effects of wall-normal variation of the roughness area fraction from the (true) variation of flow statistics, the governing equations are area-averaged using intrinsic averaging, contrary to the usually practice based on the total area (i.e., superficial averaging). Additional terms appear in the mean-momentum equation resulted from the wall-normal variation of the solid fraction and play a role in the near-wall balance. Results from surfaces with a step solidity function (e.g., cubes) will also be discussed. Compared to the sand grains, the turbine surface generates stronger form-induced fluctuations, despite weaker dispersive shear stress. This is associated with more significant form-induced productions (comparable to shear production) in Reynolds stress budgets, weaker pressure work, and, consequently, more anisotropic redistribution of turbulent kinetic energy in the roughness sublayer, which potentially leads to different turbulent responses between the two surfaces in non-equilibrium flows.
Energy Technology Data Exchange (ETDEWEB)
Sohn, Hyun Chull; Lee, Heang Nam; Park, Gil Moon [Chosun Univ., Gwangju (Korea, Republic of)
2005-10-01
In the present study, characteristics of steady state laminar flows of a straight duct connected to a 180 .deg. curved duct were examined in the entrance region through experimental and numerical analyses. For the analysis, the governing equations of laminar flows in the Cartesian coordinate system were applied. Flow characteristics such as velocity profiles and secondary flows were investigated numerically and experimentally in a square cross-sectional straight duct by the PIV system and a CFD code (STARCD). For the PIV measurement, smoke particles produced from mosquito coils. The experimental data were obtained at 9 points dividing the test sections by 400 mm. Experimental and numerical results can be summarized as follows. 1) Reynolds number, Re was increased, dimensionless velocity profiles at the outer wall were increased due to the effect of the centrifugal force and secondary flows. 2) The intensity of a secondary flow became stronger at the inner wall rather than the outer wall regardless of Reynolds number. Especially, fluid dynamic phenomenon called conner impact were observed at dimensionless axial position, x/D{sub h}=50.
International Nuclear Information System (INIS)
Tsuji, Masataka; Meshii, Toshiyuki
2011-01-01
Highlights: → A limit moment equation applicable to planar/non-planar flaw of 0 ≤ θ ≤ π found in wall thinned straight pipes was proposed. → An idea to rationally classify planar/non-planar flaw in wall thinned pipes was proposed. → The equation based on the experimental observation focused on the fracture mode. - Abstract: In this paper, a limit bending moment equation applicable to all types of planar and non-planar flaws in wall-thinned straight pipes under bending was proposed. A system to rationally classify the planar/non-planar flaws in wall-thinned pipes was suggested based on experimental observations focused on the fracture mode. The results demonstrate the importance of distinguishing between axial and circumferential long flaws in wall-thinned pipes.
Potential roughness near lithographically fabricated atom chips
DEFF Research Database (Denmark)
Krüger, Peter; Andersson, L. M.; Wildermuth, Stefan
2007-01-01
Potential roughness has been reported to severely impair experiments in magnetic microtraps. We show that these obstacles can be overcome as we measure disorder potentials that are reduced by two orders of magnitude near lithographically patterned high-quality gold layers on semiconductor atom chip...
Rough flows and homogenization in stochastic turbulence
Bailleul, I.; Catellier, R.
2016-01-01
We provide in this work a tool-kit for the study of homogenisation of random ordinary differential equations, under the form of a friendly-user black box based on the tehcnology of rough flows. We illustrate the use of this setting on the example of stochastic turbulence.
Reproducibility of surface roughness in reaming
DEFF Research Database (Denmark)
Müller, Pavel; De Chiffre, Leonardo
An investigation on the reproducibility of surface roughness in reaming was performed to document the applicability of this approach for testing cutting fluids. Austenitic stainless steel was used as a workpiece material and HSS reamers as cutting tools. Reproducibility of the results was evaluat...
Optical measurement of surface roughness in manufacturing
Energy Technology Data Exchange (ETDEWEB)
Brodmann, R.
1984-11-01
The measuring system described here is based on the light-scattering method, and was developed by Optische Werke G. Rodenstock, Munich. It is especially useful for rapid non-contact monitoring of surface roughness in production-related areas. This paper outlines the differences between this system and the common stylus instrument, including descriptions of some applications in industry.
Factors influencing surface roughness of polyimide film
International Nuclear Information System (INIS)
Yao Hong; Zhang Zhanwen; Huang Yong; Li Bo; Li Sai
2011-01-01
The polyimide (PI) films of pyromellitic dianhydride-oxydiamiline (PMDA-ODA) were fabricated using vapor deposition polymerization (VDP) method under high vacuum pressure of 10-4 Pa level. The influence of equipment, substrate temperature, the process of heating and deposition ratio of monomers on the surface roughness of the PI films was investigated. The surface topography of films was measured by interferometer microscopy and scanning electron microscopy(SEM), and the surface roughness was probed with atomic force microscopy(AFM). The results show that consecutive films can be formed when the distance from steering flow pipe to substrate is 74 cm. The surface roughnesses are 291.2 nm and 61.9 nm respectively for one-step heating process and multi-step heating process, and using fine mesh can effectively avoid the splash of materials. The surface roughness can be 3.3 nm when the deposition rate ratio of PMDA to ODA is 0.9:1, and keeping the temperature of substrate around 30 degree C is advantageous to form a film with planar micro-surface topography. (authors)
Roughly isometric minimal immersions into Riemannian manifolds
DEFF Research Database (Denmark)
Markvorsen, Steen
of the intrinsic combinatorial discrete Laplacian, and we will show that they share several analytic and geometric properties with their smooth (minimal submanifold) counterparts in $N$. The intrinsic properties thus obtained may hence serve as roughly invariant descriptors for the original metric space $X$....
Three-tier rough superhydrophobic surfaces
International Nuclear Information System (INIS)
Cao, Yuanzhi; Yuan, Longyan; Hu, Bin; Zhou, Jun
2015-01-01
A three-tier rough superhydrophobic surface was fabricated by growing hydrophobic modified (fluorinated silane) zinc oxide (ZnO)/copper oxide (CuO) hetero-hierarchical structures on silicon (Si) micro-pillar arrays. Compared with the other three control samples with a less rough tier, the three-tier surface exhibits the best water repellency with the largest contact angle 161° and the lowest sliding angle 0.5°. It also shows a robust Cassie state which enables the water to flow with a speed over 2 m s"−"1. In addition, it could prevent itself from being wetted by the droplet with low surface tension (mixed water and ethanol 1:1 in volume) which reveals a flow speed of 0.6 m s"−"1 (dropped from the height of 2 cm). All these features prove that adding another rough tier on a two-tier rough surface could futher improve its water-repellent properties. (paper)
Roughness-induced streaming in turbulent wave boundary layers
DEFF Research Database (Denmark)
Fuhrman, David R.; Sumer, B. Mutlu; Fredsøe, Jørgen
2011-01-01
-averaged streaming characteristics induced by bottom roughness variations are systematically assessed. The effects of variable roughness ratio, gradual roughness transitions, as well as changing flow orientation in plan are all considered. As part of the latter, roughness-induced secondary flows are predicted...
Self-affine roughness influence on redox reaction charge admittance
Palasantzas, G
2005-01-01
In this work we investigate the influence of self-affine electrode roughness on the admittance of redox reactions during facile charge transfer kinetics. The self-affine roughness is characterized by the rms roughness amplitude w, the correlation length xi and the roughness exponent H (0
More on neutrosophic soft rough sets and its modification
Directory of Open Access Journals (Sweden)
Emad Marei
2015-12-01
Full Text Available This paper aims to introduce and discuss anew mathematical tool for dealing with uncertainties, which is a combination of neutrosophic sets, soft sets and rough sets, namely neutrosophic soft rough set model. Also, its modification is introduced. Some of their properties are studied and supported with proved propositions and many counter examples. Some of rough relations are redefined as a neutrosophic soft rough relations. Comparisons among traditional rough model, suggested neutrosophic soft rough model and its modification, by using their properties and accuracy measures are introduced. Finally, we illustrate that, classical rough set model can be viewed as a special case of suggested models in this paper.
Turbulent boundary layer over roughness transition with variation in spanwise roughness length scale
Westerweel, Jerry; Tomas, Jasper; Eisma, Jerke; Pourquie, Mathieu; Elsinga, Gerrit; Jonker, Harm
2016-11-01
Both large-eddy simulations (LES) and water-tunnel experiments, using simultaneous stereoscopic PIV and LIF were done to investigate pollutant dispersion in a region where the surface changes from rural to urban roughness. This consists of rectangular obstacles where we vary the spanwise aspect ratio of the obstacles. A line source of passive tracer was placed upstream of the roughness transition. The objectives of the study are: (i) to determine the influence of the aspect ratio on the roughness-transition flow, and (ii) to determine the dominant mechanisms of pollutant removal from street canyons in the transition region. It is found that for a spanwise aspect ratio of 2 the drag induced by the roughness is largest of all considered cases, which is caused by a large-scale secondary flow. In the roughness transition the vertical advective pollutant flux is the main ventilation mechanism in the first three streets. Furthermore, by means of linear stochastic estimation the mean flow structure is identied that is responsible for exchange of the fluid between the roughness obstacles and the outer part of the boundary layer. Furthermore, it is found that the vertical length scale of this structure increases with increasing aspect ratio of the obstacles in the roughness region.
Effects of graphite surface roughness on bypass flow computations for an HTGR
Energy Technology Data Exchange (ETDEWEB)
Tung, Yu-Hsin, E-mail: touushin@gmail.com [Idaho National Laboratory, P.O. Box 1625, M.S. 3855, Idaho Falls, ID (United States); Johnson, Richard W., E-mail: Rich.Johnson@inl.gov [Idaho National Laboratory, P.O. Box 1625, M.S. 3855, Idaho Falls, ID (United States); Sato, Hiroyuki, E-mail: sato.hiroyuki09@jaea.go.jp [Idaho National Laboratory, P.O. Box 1625, M.S. 3855, Idaho Falls, ID (United States)
2012-11-15
Highlights: Black-Right-Pointing-Pointer CFD calculations are made of bypass flow between graphite blocks in HTGR. Black-Right-Pointing-Pointer Several turbulence models are employed to compare to friction and heat transfer correlations. Black-Right-Pointing-Pointer Parameters varied include bypass gap width and surface roughness. Black-Right-Pointing-Pointer Surface roughness causes increases in max fuel and coolant temperatures. Black-Right-Pointing-Pointer Surface roughness does not cause increase in outlet coolant temperature variation. - Abstract: Bypass flow in a prismatic high temperature gas reactor (HTGR) occurs between graphite blocks as they sit side by side in the core. Bypass flow is not intentionally designed to occur in the reactor, but is present because of tolerances in manufacture, imperfect installation and expansion and shrinkage of the blocks from heating and irradiation. It is desired to increase the knowledge of the effects of such flow; it has been suggested that it may be as much as 20% of the total helium coolant flow [INL Report 2007, INL/EXT-07-13289]. Computational fluid dynamic (CFD) simulations can provide estimates of the scale and impacts of bypass flow. Previous CFD calculations have examined the effects of bypass gap width, level and distribution of heat generation and effects of shrinkage. The present contribution examines the effects of graphite surface roughness on the bypass flow for different relative roughness factors for three gap widths. Such calculations should be validated using specific bypass flow measurements. While such experiments are currently underway for the specific reference prismatic HTGR design for the next generation nuclear plant (NGNP) program of the U.S. Dept. of Energy, the data are not yet available. To enhance confidence in the present calculations, wall shear stress and heat transfer results for several turbulence models and their associated wall treatments are first compared for steady flow in a
Numerical Investigation of Effect of Surface Roughness in a Microchannel
Energy Technology Data Exchange (ETDEWEB)
Shin, Myung Seob; Byun, Sung Jun; Yoon, Joon Yong [Hanyang University, Seoul (Korea, Republic of)
2010-05-15
In this paper, lattice Boltzmann method(LBM) results for a laminar flow in a microchannel with rough surface are presented. The surface roughness is modeled as an array of rectangular modules placed on the top and bottom surface of a parallel-plate channel. The effects of relative surface roughness, roughness distribution, and roughness size are presented in terms of the Poiseuille number. The roughness distribution characterized by the ratio of the roughness height to the spacing between the modules has a negligible effect on the flow and friction factors. Finally, a significant increase in the Poiseuille number is observed when the surface roughness is considered, and the effects of roughness on the microflow field mainly depend on the surface roughness.
Gay-Straight Alliance (GSA) Members' Engagement with Sex Education in Canadian High Schools
Lapointe, Alicia
2014-01-01
This paper offers an examination of gay-straight alliance (GSA) members' engagement with sex education, sexual health, and prejudice and discrimination in Canadian public high schools. It explores how five students' (four straight and one gay-identifying) participation in GSAs served as a springboard for learning about and challenging stereotypes;…
Siegenfeld, Billy
2009-01-01
"Standing down straight" means to stand on two feet with both stability and relaxation. Using standing down straight as the foundation of class work, Jump Rhythm Technique offers a fresh alternative to conventional systems of dance study. It bases its pedagogy on three behaviors: grounding the body so that it can move with power and efficiency,…
Directory of Open Access Journals (Sweden)
ZHANG Fan
2015-06-01
Full Text Available Due to the discrete distribution computing errors and lack of adaptability are ubiquitous in the current straight line extraction for TLS data methods. A 3D straight line segment extraction method is proposed based on spherical projection for single station terrestrial laser point clouds. Firstly, horizontal and vertical angles of each laser point are calculated by means of spherical coordinates, intensity panoramic image according to the two angles is generated. Secondly, edges which include straight line features are detected from intensity panoramic image by using of edge detection algorithm. Thirdly, great circles are detected from edges of panoramic image using spherical Hough transform. According to the axiom that a straight line segment in 3D space is a spherical great circle after spherical projection, detecting great circles from spherical projected data sets is essentially detecting straight line segments from 3D data sets without spherical projection. Finally, a robust 3D straight line fitting method is employed to fitting the straight lines and calculating parameters of the straight line segments. Experiments using different data sets and comparison with other methods show the accuracy and applicability of the proposed method.
A simple algorithm for computing positively weighted straight skeletons of monotone polygons☆
Biedl, Therese; Held, Martin; Huber, Stefan; Kaaser, Dominik; Palfrader, Peter
2015-01-01
We study the characteristics of straight skeletons of monotone polygonal chains and use them to devise an algorithm for computing positively weighted straight skeletons of monotone polygons. Our algorithm runs in O(nlogn) time and O(n) space, where n denotes the number of vertices of the polygon. PMID:25648376
A simple algorithm for computing positively weighted straight skeletons of monotone polygons.
Biedl, Therese; Held, Martin; Huber, Stefan; Kaaser, Dominik; Palfrader, Peter
2015-02-01
We study the characteristics of straight skeletons of monotone polygonal chains and use them to devise an algorithm for computing positively weighted straight skeletons of monotone polygons. Our algorithm runs in [Formula: see text] time and [Formula: see text] space, where n denotes the number of vertices of the polygon.
International Nuclear Information System (INIS)
Chen Benyong; Zhang Enzheng; Yan Liping; Li Chaorong; Tang Wuhua; Feng Qibo
2009-01-01
Not only the magnitude but also the position of straightness errors are of concern to users. However, current laser interferometers used for measuring straightness seldom give the relative position of the straightness error. To solve this problem, a laser interferometer for measuring straightness and its position based on heterodyne interferometry is proposed. The optical configuration of the interferometer is designed and the measurement principle is analyzed theoretically. Two experiments were carried out. The first experiment verifies the validity and repeatability of the interferometer by measuring a linear stage. Also, the second one for measuring a flexure-hinge stage demonstrates that the interferometer is capable of nanometer measurement accuracy. These results show that this interferometer has advantages of simultaneously measuring straightness error and the relative position with high precision, and a compact structure.
Youth Empowerment and High School Gay-Straight Alliances
Muraco, Anna; Subramaniam, Aarti; Laub, Carolyn
2010-01-01
In the field of positive youth development programs, “empowerment” is used interchangeably with youth activism, leadership, civic participation and self-efficacy. However, few studies have captured what empowerment means to young people in diverse contexts. This article explores how youth define and experience empowerment in youth-led organizations characterized by social justice goals: high school Gay-Straight Alliances (GSAs). Through focus group interviews, fifteen youth leaders of GSAs from different regions of California explain what they think empowerment means and how they became empowered through their involvement with the GSA. Youth describe three inter-related dimensions of empowerment: personal empowerment, relational empowerment, and strategic empowerment through having and using knowledge. When these three dimensions are experienced in combination, GSA leaders have the potential for individual and collective empowerment as agents of social change at school. By understanding these youth's perspectives on the meanings of empowerment, this article clarifies the conceptual arena for future studies of socially marginalized youth and of positive youth development. PMID:19636734
A composite vacuum barrier for the LHC short straight section
International Nuclear Information System (INIS)
Jenny, B.; Rohmig, P.; Uriarte, J.M.
1996-01-01
The lattice of the CERN Large Hadron Collider (LHC) will contain 384 Short Straight Section (SSS) units, one in every 53 m half-cell. The SSS is composed of a twin aperture high-field superconducting quadrupole and of two combined-function corrector magnets operating in pressurized helium at 1.9 K. The SSS cryostat contains also a barrier for sectorisation of the insulation vacuum. The vacuum barrier is mounted between the helium vessel and the vacuum enclosure. Its functions are to limit the extent of eventual helium leaks and to facilitate the leak detection and the pumping-down from atmospheric pressure. During installation of the LHC, the vacuum barrier permits independent testing of the half-cells, thus enabling higher installation rates. In parallel to a conventional barrier made out of austenitic stainless steel, a barrier of composite material was developed, taking advantage of the lower thermal conductivity of glass fibre reinforced epoxy resin, and with the aim of reducing costs for LHC. The thermo-mechanical design together with the conception and the moulding techniques used for the manufacture of the prototype are described. Bonding techniques for the leak tight stainless steel composite interfaces are presented and test results shown. Results on the mechanical performance and on the helium tests carried out on the prototype are given
Straight cylindrical seal for high-performance turbomachines
Hendricks, Robert C.
1987-01-01
A straight cylindrical seal configuration representing the seal for a high-performance turbopump (e.g., the space shuttle main engine fuel pump) was tested under static (nonrotating) conditions. The test data included critical mass flux and pressure profiles over a wide range of inlet temperatures and pressures for fluid nitrogen and fluid hydrogen with the seal in concentric and fully eccentric positions. The critical mass fluxes (or leakage rates) for the concentric and fully eccentric configurations were nearly the same when based on stagnation conditions upstream of the seal. The fully eccentric configuration pressure profiles of the gas and liquid were different. Further, the pressure differences between the maximum and the minimum clearance positions were highly dependent on the geometric conditions, the temperature, and the absolute pressure at both the inlet and the exit. The pressure differences were greatest in the inlet region. The results, although complex, tend to follow the corresponding-states principles for critical flows. Gaseous injection near the seal exit plane significantly altered the pressure profiles and could be used to control turbomachine instabilities.
Receptivity of Hypersonic Boundary Layers over Straight and Flared Cones
Balakumar, Ponnampalam; Kegerise, Michael A.
2010-01-01
The effects of adverse pressure gradients on the receptivity and stability of hypersonic boundary layers were numerically investigated. Simulations were performed for boundary layer flows over a straight cone and two flared cones. The steady and the unsteady flow fields were obtained by solving the two-dimensional Navier-Stokes equations in axi-symmetric coordinates using the 5th order accurate weighted essentially non-oscillatory (WENO) scheme for space discretization and using third-order total-variation-diminishing (TVD) Runge-Kutta scheme for time integration. The mean boundary layer profiles were analyzed using local stability and non-local parabolized stability equations (PSE) methods. After the most amplified disturbances were identified, two-dimensional plane acoustic waves were introduced at the outer boundary of the computational domain and time accurate simulations were performed. The adverse pressure gradient was found to affect the boundary layer stability in two important ways. Firstly, the frequency of the most amplified second-mode disturbance was increased relative to the zero pressure gradient case. Secondly, the amplification of first- and second-mode disturbances was increased. Although an adverse pressure gradient enhances instability wave growth rates, small nose-tip bluntness was found to delay transition due to the low receptivity coefficient and the resulting weak initial amplitude of the instability waves. The computed and measured amplitude-frequency spectrums in all three cases agree very well in terms of frequency and the shape except for the amplitude.
Youth empowerment and high school Gay-Straight Alliances.
Russell, Stephen T; Muraco, Anna; Subramaniam, Aarti; Laub, Carolyn
2009-08-01
In the field of positive youth development programs, "empowerment" is used interchangeably with youth activism, leadership, civic participation and self-efficacy. However, few studies have captured what empowerment means to young people in diverse contexts. This article explores how youth define and experience empowerment in youth-led organizations characterized by social justice goals: high school Gay-Straight Alliances (GSAs). Through focus group interviews, fifteen youth leaders of GSAs from different regions of California explain what they think empowerment means and how they became empowered through their involvement with the GSA. Youth describe three inter-related dimensions of empowerment: personal empowerment, relational empowerment, and strategic empowerment through having and using knowledge. When these three dimensions are experienced in combination, GSA leaders have the potential for individual and collective empowerment as agents of social change at school. By understanding these youth's perspectives on the meanings of empowerment, this article clarifies the conceptual arena for future studies of socially marginalized youth and of positive youth development.
Electrical and Magnetic Performance of the LHC Short Straight Sections
Sanfilippo, S; Bottura, L; Buzio, M; Coccoli, M; García-Pérez, J; Pugnat, P; Sammut, N; Siemko, A; Smirnov, N; Stafiniak, A; Wildner, E
2006-01-01
The Short Straight Section (SSS) for the Large Hadron Collider arcs, containing in a common cryostat the lattice quadrupoles and correction magnets, have now entered series production. The foremost features of the lattice quadrupole magnets are a two-in-one structure containing two 56Â mm aperture, two-layers coils wound from 15.1Â mm wide NbTi cables, enclosed by the stainless steel collars and ferromagnetic yoke, and inserted into the inertia tube. Systematic cryogenic tests are performed at CERN in order to qualify these magnets with respect to their cryogenic and electrical integrity, the quench performance and the field quality in all operating conditions. This paper reports the main results obtained during tests and measurements in superfluid helium. The electrical characteristics, the insulation measurements and the quench performance are compared to the specifications and expected performances for these magnets. The field in the main quadrupole is measured using three independent systems: 10-m lon...
Velocity and turbulence at a wing-wall abutment
Indian Academy of Sciences (India)
Experimental investigation of the 3D turbulent ﬂow ﬁeld around a 45° wing-wall abutment, resting on a rough rigid bed, is reported. The experiment was conducted ... The shear stresses acting on the bed around the abutment are estimated from the Reynolds stresses and velocity gradients. The data presented in this study ...
Anomalous roughness of turbulent interfaces with system size dependent local roughness exponent
International Nuclear Information System (INIS)
Balankin, Alexander S.; Matamoros, Daniel Morales
2005-01-01
In a system far from equilibrium the system size can play the role of control parameter that governs the spatiotemporal dynamics of the system. Accordingly, the kinetic roughness of interfaces in systems far from equilibrium may depend on the system size. To get an insight into this problem, we performed a detailed study of rough interfaces formed in paper combustion experiments. Using paper sheets of different width λ, we found that the turbulent flame fronts display anomalous multi-scaling characterized by non-universal global roughness exponent α and by the system size dependent spectrum of local roughness exponents, ζ q (λ)=ζ 1 (1)q -ω λ φ q =0.93q -0.15 . The structure factor of turbulent flame fronts also exhibits unconventional scaling dependence on λ. These results are expected to apply to a broad range of far from equilibrium systems when the kinetic energy fluctuations exceed a certain critical value.
Dry deposition on smooth and rough urban surfaces
International Nuclear Information System (INIS)
Roed, J.
1987-01-01
Following the Chernobyl accident, dry deposition velocities on smooth surfaces indoors and outdoors have been measured in Denmark. Internal wall surfaces gave deposition velocities of 0.0008-0.0009 cm/s for 131I and 0.0001-0.0002 cm/s for 134Cs and 103Ru. Internal floor surfaces gave higher values for the deposition velocities: for 131I, 0.002 cm/s and for 134Cs and 103Ru, 0.0005-0.0013 cm/s. The deposition velocities on vertical and horizontal external surfaces were nearly equal. Those for 131I were found as 0.02-0.03 cm/s and for 137Cs as 0.001-0.002 cm/s. On external rough surfaces such as grass and corrugated roof material the deposition velocities for 134Cs and 103Ru were 0.03-0.05 cm/s. For iodine, however, deposition velocities were higher for clipped grass (2 cm/s) than for roof material (0.2-0.4 cm/s). The results show that internal deposition velocities are considerably lower than those on external smooth surfaces, and that the deposition velocities on rough surfaces are an order of magnitude higher than on smooth surfaces. It was also shown that the deposition velocities of iodine are considerably higher than those of cesium and ruthenium. This work was supported by EEC Radiation Protection Programme No B16-107-DK and by NKA, The Nordic Liaison Committee for Atomic Energy. (author)
Deposition of CsI aerosol in horizontal straight pipes in WIND project
International Nuclear Information System (INIS)
Sugimoto, J.; Maruyama, Y.; Igarashi, M.; Hidaka, A.; Maeda, A.; Harada, Y.; Hashimoto, K.
1996-01-01
In the WIND Project at Japan Atomic Energy Research Institute, the aerosol behaviors such as deposition, revaporization and resuspension have been investigated under the severe accident conditions. The present paper describes the deposition of CsI aerosol in horizontal straight pipes. The test results showed that the aerosol deposition depended on thermo-fluid dynamic characteristics of the carrier gas. In the test with the temperature gradient of the pipe, the deposition of CsI was remarkable within the downstream side, where the temperature of the gas was higher than that of the pipe wall. It is thus supposed that the major mechanism of the deposition was thermophoresis caused by the temperature gradient within the gas phase. However, circumferential distribution of the deposited CsI was influenced by the argon flow rate. In laminar flow case, larger amount of CsI was deposited on the ceiling than the floor area. Three-dimensional thermo-fluid dynamic analysis suggested that much sharper radial temperature gradient was developed within the gas near the ceiling area due to the formation of a natural convective secondary flow. This could result in the promotion of the thermophoretic aerosol deposition. On the other hand, slight circumferential distribution was observed in case of the high flow rate, probably due to a uniform temperature field. It was also found that the close coupling of the FP behavior and the detailed thermohydraulic analyses is essential in order to accurately predict the CsI deposition in the pipe. The findings on aerosol behaviors will also be utilized for the evaluation of sodium aerosol behaviors of fast reactors. (author)
Generalized rough sets hybrid structure and applications
Mukherjee, Anjan
2015-01-01
The book introduces the concept of “generalized interval valued intuitionistic fuzzy soft sets”. It presents the basic properties of these sets and also, investigates an application of generalized interval valued intuitionistic fuzzy soft sets in decision making with respect to interval of degree of preference. The concept of “interval valued intuitionistic fuzzy soft rough sets” is discussed and interval valued intuitionistic fuzzy soft rough set based multi criteria group decision making scheme is presented, which refines the primary evaluation of the whole expert group and enables us to select the optimal object in a most reliable manner. The book also details concept of interval valued intuitionistic fuzzy sets of type 2. It presents the basic properties of these sets. The book also introduces the concept of “interval valued intuitionistic fuzzy soft topological space (IVIFS topological space)” together with intuitionistic fuzzy soft open sets (IVIFS open sets) and intuitionistic fuzzy soft cl...
Single-layer model for surface roughness.
Carniglia, C K; Jensen, D G
2002-06-01
Random roughness of an optical surface reduces its specular reflectance and transmittance by the scattering of light. The reduction in reflectance can be modeled by a homogeneous layer on the surface if the refractive index of the layer is intermediate to the indices of the media on either side of the surface. Such a layer predicts an increase in the transmittance of the surface and therefore does not provide a valid model for the effects of scatter on the transmittance. Adding a small amount of absorption to the layer provides a model that predicts a reduction in both reflectance and transmittance. The absorbing layer model agrees with the predictions of a scalar scattering theory for a layer with a thickness that is twice the rms roughness of the surface. The extinction coefficient k for the layer is proportional to the thickness of the layer.
Offshore Wind Power at Rough Sea
DEFF Research Database (Denmark)
Petersen, Kristian Rasmus; Madsen, Erik Skov; Bilberg, Arne
2013-01-01
This study compare the current operations and maintenance issues of one offshore wind park at very rough sea conditions and two onshore wind parks. Through a detailed data analysis and case studies this study identifies how improvements have been made in maintenance of large wind turbines. Howeve......, the study has also revealed the need for new maintenance models including a shift from breakdown and preventive maintenances and towards more predictive maintenance to reduce the cost of energy for offshore wind energy installations in the future.......This study compare the current operations and maintenance issues of one offshore wind park at very rough sea conditions and two onshore wind parks. Through a detailed data analysis and case studies this study identifies how improvements have been made in maintenance of large wind turbines. However...
The contact sport of rough surfaces
Carpick, Robert W.
2018-01-01
Describing the way two surfaces touch and make contact may seem simple, but it is not. Fully describing the elastic deformation of ideally smooth contacting bodies, under even low applied pressure, involves second-order partial differential equations and fourth-rank elastic constant tensors. For more realistic rough surfaces, the problem becomes a multiscale exercise in surface-height statistics, even before including complex phenomena such as adhesion, plasticity, and fracture. A recent research competition, the “Contact Mechanics Challenge” (1), was designed to test various approximate methods for solving this problem. A hypothetical rough surface was generated, and the community was invited to model contact with this surface with competing theories for the calculation of properties, including contact area and pressure. A supercomputer-generated numerical solution was kept secret until competition entries were received. The comparison of results (2) provides insights into the relative merits of competing models and even experimental approaches to the problem.
Prediction of Ductile Fracture Surface Roughness Scaling
DEFF Research Database (Denmark)
Needleman, Alan; Tvergaard, Viggo; Bouchaud, Elisabeth
2012-01-01
. Ductile crack growth in a thin strip under mode I, overall plane strain, small scale yielding conditions is analyzed. Although overall plane strain loading conditions are prescribed, full 3D analyses are carried out to permit modeling of the three dimensional material microstructure and of the resulting......Experimental observations have shown that the roughness of fracture surfaces exhibit certain characteristic scaling properties. Here, calculations are carried out to explore the extent to which a ductile damage/fracture constitutive relation can be used to model fracture surface roughness scaling...... three dimensional stress and deformation states that develop in the fracture process region. An elastic-viscoplastic constitutive relation for a progressively cavitating plastic solid is used to model the material. Two populations of second phase particles are represented: large inclusions with low...
Estimation of gloss from rough surface parameters
Simonsen, Ingve; Larsen, Åge G.; Andreassen, Erik; Ommundsen, Espen; Nord-Varhaug, Katrin
2005-12-01
Gloss is a quantity used in the optical industry to quantify and categorize materials according to how well they scatter light specularly. With the aid of phase perturbation theory, we derive an approximate expression for this quantity for a one-dimensional randomly rough surface. It is demonstrated that gloss depends in an exponential way on two dimensionless quantities that are associated with the surface randomness: the root-mean-square roughness times the perpendicular momentum transfer for the specular direction, and a correlation function dependent factor times a lateral momentum variable associated with the collection angle. Rigorous Monte Carlo simulations are used to access the quality of this approximation, and good agreement is observed over large regions of parameter space.
Sparseness and Roughness of Foreign Exchange Rates
Vandewalle, N.; Ausloos, M.
An accurate multiaffine analysis of 23 foreign currency exchange rates has been performed. The roughness exponent H1 which characterizes the excursion of the exchange rate has been numerically measured. The degree of intermittency C1 has been also estimated. In the (H1,C1) phase diagram, the currency exchange rates are dispersed in a wide region around the Brownian motion value (H1=0.5,C1=0) and have a significantly intermittent component (C1≠0).
Rough surface scattering simulations using graphics cards
International Nuclear Information System (INIS)
Klapetek, Petr; Valtr, Miroslav; Poruba, Ales; Necas, David; Ohlidal, Miloslav
2010-01-01
In this article we present results of rough surface scattering calculations using a graphical processing unit implementation of the Finite Difference in Time Domain algorithm. Numerical results are compared to real measurements and computational performance is compared to computer processor implementation of the same algorithm. As a basis for computations, atomic force microscope measurements of surface morphology are used. It is shown that the graphical processing unit capabilities can be used to speedup presented computationally demanding algorithms without loss of precision.
Roughness Length Variability over Heterogeneous Surfaces
2010-03-01
2004), the influence of variable roughness reaches its maximum at the height of local 0z and vanishes at the so- called blending height (Wieringa...the distribution of visibility restrictors such as low clouds, fog, haze, dust, and pollutants . An improved understanding of ABL structure...R. D., B. H. Lynn, A. Boone, W.-K. Tao, and J. Simpson, 2001: The influence of soil moisture, coastline curvature, and land-breeze circulations on
The characteristic function of rough Heston models
Euch, Omar El; Rosenbaum, Mathieu
2016-01-01
It has been recently shown that rough volatility models, where the volatility is driven by a fractional Brownian motion with small Hurst parameter, provide very relevant dynamics in order to reproduce the behavior of both historical and implied volatilities. However, due to the non-Markovian nature of the fractional Brownian motion, they raise new issues when it comes to derivatives pricing. Using an original link between nearly unstable Hawkes processes and fractional volatility models, we c...
Radiative transfer model for contaminated rough slabs.
Andrieu, François; Douté, Sylvain; Schmidt, Frédéric; Schmitt, Bernard
2015-11-01
We present a semi-analytical model to simulate the bidirectional reflectance distribution function (BRDF) of a rough slab layer containing impurities. This model has been optimized for fast computation in order to analyze massive hyperspectral data by a Bayesian approach. We designed it for planetary surface ice studies but it could be used for other purposes. It estimates the bidirectional reflectance of a rough slab of material containing inclusions, overlaying an optically thick media (semi-infinite media or stratified media, for instance granular material). The inclusions are assumed to be close to spherical and constituted of any type of material other than the ice matrix. It can be any other type of ice, mineral, or even bubbles defined by their optical constants. We assume a low roughness and we consider the geometrical optics conditions. This model is thus applicable for inclusions larger than the considered wavelength. The scattering on the inclusions is assumed to be isotropic. This model has a fast computation implementation and thus is suitable for high-resolution hyperspectral data analysis.
Multi-decadal Arctic sea ice roughness.
Tsamados, M.; Stroeve, J.; Kharbouche, S.; Muller, J. P., , Prof; Nolin, A. W.; Petty, A.; Haas, C.; Girard-Ardhuin, F.; Landy, J.
2017-12-01
The transformation of Arctic sea ice from mainly perennial, multi-year ice to a seasonal, first-year ice is believed to have been accompanied by a reduction of the roughness of the ice cover surface. This smoothening effect has been shown to (i) modify the momentum and heat transfer between the atmosphere and ocean, (ii) to alter the ice thickness distribution which in turn controls the snow and melt pond repartition over the ice cover, and (iii) to bias airborne and satellite remote sensing measurements that depend on the scattering and reflective characteristics over the sea ice surface topography. We will review existing and novel remote sensing methodologies proposed to estimate sea ice roughness, ranging from airborne LIDAR measurement (ie Operation IceBridge), to backscatter coefficients from scatterometers (ASCAT, QUICKSCAT), to multi angle maging spectroradiometer (MISR), and to laser (Icesat) and radar altimeters (Envisat, Cryosat, Altika, Sentinel-3). We will show that by comparing and cross-calibrating these different products we can offer a consistent multi-mission, multi-decadal view of the declining sea ice roughness. Implications for sea ice physics, climate and remote sensing will also be discussed.
ROUGHNESS ANALYSIS OF VARIOUSLY POLISHED NIOBIUM SURFACES
Energy Technology Data Exchange (ETDEWEB)
Ribeill, G.; Reece, C.
2008-01-01
Niobium superconducting radio frequency (SRF) cavities have gained widespread use in accelerator systems. It has been shown that surface roughness is a determining factor in the cavities’ effi ciency and maximum accelerating potential achievable through this technology. Irregularities in the surface can lead to spot heating, undesirable local electrical fi eld enhancement and electron multipacting. Surface quality is typically ensured through the use of acid etching in a Buffered Chemical Polish (BCP) bath and electropolishing (EP). In this study, the effects of these techniques on surface morphology have been investigated in depth. The surface of niobium samples polished using different combinations of these techniques has been characterized through atomic force microscopy (AFM) and stylus profi lometry across a range of length scales. The surface morphology was analyzed using spectral techniques to determine roughness and characteristic dimensions. Experimentation has shown that this method is a valuable tool that provides quantitative information about surface roughness at different length scales. It has demonstrated that light BCP pretreatment and lower electrolyte temperature favors a smoother electropolish. These results will allow for the design of a superior polishing process for niobium SRF cavities and therefore increased accelerator operating effi ciency and power.
Modeling superhydrophobic surfaces comprised of random roughness
Samaha, M. A.; Tafreshi, H. Vahedi; Gad-El-Hak, M.
2011-11-01
We model the performance of superhydrophobic surfaces comprised of randomly distributed roughness that resembles natural surfaces, or those produced via random deposition of hydrophobic particles. Such a fabrication method is far less expensive than ordered-microstructured fabrication. The present numerical simulations are aimed at improving our understanding of the drag reduction effect and the stability of the air-water interface in terms of the microstructure parameters. For comparison and validation, we have also simulated the flow over superhydrophobic surfaces made up of aligned or staggered microposts for channel flows as well as streamwise or spanwise ridge configurations for pipe flows. The present results are compared with other theoretical and experimental studies. The numerical simulations indicate that the random distribution of surface roughness has a favorable effect on drag reduction, as long as the gas fraction is kept the same. The stability of the meniscus, however, is strongly influenced by the average spacing between the roughness peaks, which needs to be carefully examined before a surface can be recommended for fabrication. Financial support from DARPA, contract number W91CRB-10-1-0003, is acknowledged.
Rough – Granular Computing knowledge discovery models
Directory of Open Access Journals (Sweden)
Mohammed M. Eissa
2016-11-01
Full Text Available Medical domain has become one of the most important areas of research in order to richness huge amounts of medical information about the symptoms of diseases and how to distinguish between them to diagnose it correctly. Knowledge discovery models play vital role in refinement and mining of medical indicators to help medical experts to settle treatment decisions. This paper introduces four hybrid Rough – Granular Computing knowledge discovery models based on Rough Sets Theory, Artificial Neural Networks, Genetic Algorithm and Rough Mereology Theory. A comparative analysis of various knowledge discovery models that use different knowledge discovery techniques for data pre-processing, reduction, and data mining supports medical experts to extract the main medical indicators, to reduce the misdiagnosis rates and to improve decision-making for medical diagnosis and treatment. The proposed models utilized two medical datasets: Coronary Heart Disease dataset and Hepatitis C Virus dataset. The main purpose of this paper was to explore and evaluate the proposed models based on Granular Computing methodology for knowledge extraction according to different evaluation criteria for classification of medical datasets. Another purpose is to make enhancement in the frame of KDD processes for supervised learning using Granular Computing methodology.
Dynamic mechanical properties of straight titanium alloy arch wires.
Kusy, R P; Wilson, T W
1990-10-01
Eight straight-wire materials were studied: an orthodontic titanium-molybdenum (Ti-Mo) product, TMA; three orthodontic nickel-titanium (Ni-Ti) products, Nitinol, Titanal, and Orthonol; three prototype alloys, a martensitic, an austenitic, and a biphasic alloy; and a hybrid shape-memory-effect product, Biometal. Each wire was prepared with a length-to-cross-sectional area of at least 3600 cm-1. With an Autovibron Model DDV-II-C used in the tensile mode, each sample was scanned from -120 to +200 degrees C at 2 degrees C/min. From the data base, plots of the log storage modulus, log tan delta, and percent change in length vs. temperature were generated. Results showed that the dynamic mechanical properties of the alloys within this TI system are quite different. The Ti-Mo alloy, TMA, was invariant with temperature, having a modulus of 7.30 x 10(11) dyne/cm2 (10.6 x 10(6) psi). The three cold-worked alloys--Nitinol, Titanal, and Orthonol--appeared to be similar, having a modulus of 5.74 x 10(11) dyne/cm2 (8.32 x 10(6) psi). The biphasic shape-memory alloy displayed a phase transformation near ambient temperature; whereas the hybrid shape-memory product, Biometal, underwent a 3-5% change in length during its transformation between 95 and 125 degrees C. Among the Ni-Ti wires tested, several different types of alloys were represented by this intermetallic material.
Straight velocity boundaries in the lattice Boltzmann method
Latt, Jonas; Chopard, Bastien; Malaspinas, Orestis; Deville, Michel; Michler, Andreas
2008-05-01
Various ways of implementing boundary conditions for the numerical solution of the Navier-Stokes equations by a lattice Boltzmann method are discussed. Five commonly adopted approaches are reviewed, analyzed, and compared, including local and nonlocal methods. The discussion is restricted to velocity Dirichlet boundary conditions, and to straight on-lattice boundaries which are aligned with the horizontal and vertical lattice directions. The boundary conditions are first inspected analytically by applying systematically the results of a multiscale analysis to boundary nodes. This procedure makes it possible to compare boundary conditions on an equal footing, although they were originally derived from very different principles. It is concluded that all five boundary conditions exhibit second-order accuracy, consistent with the accuracy of the lattice Boltzmann method. The five methods are then compared numerically for accuracy and stability through benchmarks of two-dimensional and three-dimensional flows. None of the methods is found to be throughout superior to the others. Instead, the choice of a best boundary condition depends on the flow geometry, and on the desired trade-off between accuracy and stability. From the findings of the benchmarks, the boundary conditions can be classified into two major groups. The first group comprehends boundary conditions that preserve the information streaming from the bulk into boundary nodes and complete the missing information through closure relations. Boundary conditions in this group are found to be exceptionally accurate at low Reynolds number. Boundary conditions of the second group replace all variables on boundary nodes by new values. They exhibit generally much better numerical stability and are therefore dedicated for use in high Reynolds number flows.
Forooghi, Pourya; Stroh, Alexander; Schlatter, Philipp; Frohnapfel, Bettina
2018-04-01
Direct numerical simulations are used to investigate turbulent flow in rough channels, in which topographical parameters of the rough wall are systematically varied at a fixed friction Reynolds number of 500, based on a mean channel half-height h and friction velocity. The utilized roughness generation approach allows independent variation of moments of the surface height probability distribution function [thus root-mean-square (rms) surface height, skewness, and kurtosis], surface mean slope, and standard deviation of the roughness peak sizes. Particular attention is paid to the effect of the parameter Δ defined as the normalized height difference between the highest and lowest roughness peaks. This parameter is used to understand the trends of the investigated flow variables with departure from the idealized case where all roughness elements have the same height (Δ =0 ). All calculations are done in the fully rough regime and for surfaces with high slope (effective slope equal to 0.6-0.9). The rms roughness height is fixed for all cases at 0.045 h and the skewness and kurtosis of the surface height probability density function vary in the ranges -0.33 to 0.67 and 1.9 to 2.6, respectively. The goal of the paper is twofold: first, to investigate the possible effect of topographical parameters on the mean turbulent flow, Reynolds, and dispersive stresses particularly in the vicinity of the roughness crest, and second, to investigate the possibility of using the wall-normal turbulence intensity as a physical parameter for parametrization of the flow. Such a possibility, already suggested for regular roughness in the literature, is here extended to irregular roughness.
Low Horizontal Beta Function In Long Straights Of The NSLS-II Lattice
International Nuclear Information System (INIS)
Fanglei, L.; Bengtsson, J.; Guo, W.; Krinsky, S.; Li, Y.; Yang, L.
2011-01-01
The NSLS-II storage ring lattice is comprised of 30 DBA cells arranged in 15 superperiods. There are 15 long straight sections (9.3m) for injection, RF and insertion devices and 15 short straights (6.6m) for insertion devices. In the baseline lattice, the short straights have small horizontal and vertical beta functions but the long straights have large horizontal beta function optimized for injection. In this paper, we explore the possibility of maintaining three long straights with large horizontal beta function while providing the other 12 long straights with smaller horizontal beta function to optimize the brightness of insertion devices. Our study considers the possible linear lattice solutions as well as characterizing the nonlinear dynamics. Results are reported on optimization of dynamic aperture required for good injection efficiency and adequate Touschek lifetime. This paper discusses dynamic aperture optimization for the NSLS-II lattice with alternate high and low horizontal beta function in the long straights, which is proposed for the optimization of the brightness of insertion devices. The linear optics is optimized to meet the requirements of lattice function and source properties. Nonlinear optimization for a lattice with working point at (37.18, 16.2) is performed. Considering the realistic magnets errors and physical apertures, we calculate the frequency maps and plot the tune footprint. The results show that the lattice with high-low beta function has adequate dynamic aperture for good injection efficiency and sufficient Touschek lifetime.
Blankena, Roos; Kleinloog, Rachel; Verweij, Bon H.; van Ooij, Pim; ten Haken, Bennie; Luijten, Peter R.; Rinkel, Gabriel J.E.; Zwanenburg, Jaco J.M.
2016-01-01
Purpose To develop a method for semi-quantitative wall thickness assessment on in vivo 7.0 tesla (7T) MRI images of intracranial aneurysms for studying the relation between apparent aneurysm wall thickness and wall shear stress. Materials and Methods Wall thickness was analyzed in 11 unruptured aneurysms in 9 patients, who underwent 7T MRI with a TSE based vessel wall sequence (0.8 mm isotropic resolution). A custom analysis program determined the in vivo aneurysm wall intensities, which were normalized to signal of nearby brain tissue and were used as measure for apparent wall thickness (AWT). Spatial wall thickness variation was determined as the interquartile range in AWT (the middle 50% of the AWT range). Wall shear stress was determined using phase contrast MRI (0.5 mm isotropic resolution). We performed visual and statistical comparisons (Pearson’s correlation) to study the relation between wall thickness and wall shear stress. Results 3D colored AWT maps of the aneurysms showed spatial AWT variation, which ranged from 0.07 to 0.53, with a mean variation of 0.22 (a variation of 1.0 roughly means a wall thickness variation of one voxel (0.8mm)). In all aneurysms, AWT was inversely related to WSS (mean correlation coefficient −0.35, P<0.05). Conclusions A method was developed to measure the wall thickness semi-quantitatively, using 7T MRI. An inverse correlation between wall shear stress and AWT was determined. In future studies, this non-invasive method can be used to assess spatial wall thickness variation in relation to pathophysiologic processes such as aneurysm growth and –rupture. PMID:26892986
Alter, Scott M; Haim, Eithan D; Sullivan, Alex H; Clayton, Lisa M
2018-02-17
Direct laryngoscopy can be performed using curved or straight blades, and providers usually choose the blade they are most comfortable with. However, curved blades are anecdotally thought of as easier to use than straight blades. We seek to compare intubation success rates of paramedics using curved versus straight blades. Design: retrospective chart review. hospital-based suburban ALS service with 20,000 annual calls. prehospital patients with any direct laryngoscopy intubation attempt over almost 9years. First attempt and overall success rates were calculated for attempts with curved and straight blades. Differences between the groups were calculated. 2299 patients were intubated by direct laryngoscopy. 1865 had attempts with a curved blade, 367 had attempts with a straight blade, and 67 had attempts with both. Baseline characteristics were similar between groups. First attempt success was 86% with a curved blade and 73% with a straight blade: a difference of 13% (95% CI: 9-17). Overall success was 96% with a curved blade and 81% with a straight blade: a difference of 15% (95% CI: 12-18). There was an average of 1.11 intubation attempts per patient with a curved blade and 1.13 attempts per patient with a straight blade (2% difference, 95% CI: -3-7). Our study found a significant difference in intubation success rates between laryngoscope blade types. Curved blades had higher first attempt and overall success rates when compared to straight blades. Paramedics should consider selecting a curved blade as their tool of choice to potentially improve intubation success. Copyright © 2018 Elsevier Inc. All rights reserved.
The surface roughness and planetary boundary layer
Telford, James W.
1980-03-01
Applications of the entrainment process to layers at the boundary, which meet the self similarity requirements of the logarithmic profile, have been studied. By accepting that turbulence has dominating scales related in scale length to the height above the surface, a layer structure is postulated wherein exchange is rapid enough to keep the layers internally uniform. The diffusion rate is then controlled by entrainment between layers. It has been shown that theoretical relationships derived on the basis of using a single layer of this type give quantitatively correct factors relating the turbulence, wind and shear stress for very rough surface conditions. For less rough surfaces, the surface boundary layer can be divided into several layers interacting by entrainment across each interface. This analysis leads to the following quantitatively correct formula compared to published measurements. 1 24_2004_Article_BF00877766_TeX2GIFE1.gif {σ _w }/{u^* } = ( {2/{9Aa}} )^{{1/4}} ( {1 - 3^{{1/2}{ a/k{d_n }/z{σ _w }/{u^* }z/L} )^{{1/4}} = 1.28(1 - 0.945({{σ _w }/{u^* }}}) {{z/L}})^{{1/4 where u^* = ( {{tau/ρ}}^{{1/2}}, σ w is the standard deviation of the vertical velocity, z is the height and L is the Obukhov scale lenght. The constants a, A, k and d n are the entrainment constant, the turbulence decay constant, Von Karman's constant, and the layer depth derived from the theory. Of these, a and A, are universal constants and not empirically determined for the boundary layer. Thus the turbulence needed for the plume model of convection, which resides above these layers and reaches to the inversion, is determined by the shear stress and the heat flux in the surface layers. This model applies to convection in cool air over a warm sea. The whole field is now determined except for the temperature of the air relative to the water, and the wind, which need a further parameter describing sea surface roughness. As a first stop to describing a surface where roughness elements
Elbing, Brian; Dowling, David; Solomon, Michael; Bian, Sherry; Ceccio, Steven
2007-11-01
A recent experiment at the U.S. Navy's Large Cavitation Channel (LCC) investigated the effect of wall roughness on wall-injection polymer drag reduction (PDR) within a high-Reynolds-number (10^7 to 2x10^8 based on downstream distance) turbulent boundary layer (TBL). Testing was performed in two parts: 1) PDR experiment on a 12.9 m long, 3.05 m wide hydro-dynamically smooth flat plate and 2) PDR experiment on the same model with the entire surface roughened. The roughness was produced by blowing glass beads into epoxy paint that was applied to the entire model. The roughened model had an average roughness height ranging between 307 and 1154 μm. Drag reduction was determined using six, stream-wise located integrated skin-friction balances. In addition to skin-friction measurements, sampling was performed at three stream-wise located ports. The sampling ports were used to determine the amount of degradation, if any, caused by the turbulent flow on the polymer. Both the skin-friction measurements and sampling analysis indicates that wall roughness in a turbulent boundary layer significantly increases degradation of the polymer solution.
Laminar flow in porous pipes and ducts with variable suction or injection at the wall
International Nuclear Information System (INIS)
Souza Araujo, P.M. de; Stuckenbruck, S.
1977-01-01
The laminar flow of an incompressible fluid is analysed along a porous-walled straight circular tube and a flat duct formed by parallel porous plates. The non-similarity of velocity profiles is verified and the analytical solution is obtained by expanding the axial velocity component in a power series. The mass flow through the walls is taken into consideration as an application of Darcy's Law. Adverse axial pressure gradients and occasional reverse flow near the wall are pointed out in the work. (Author) [pt
Transmission of fast highly charged ions through straight and tapered glass capillaries
International Nuclear Information System (INIS)
Ayyad, Asma M; Keerthisinghe, D; Kayani, A; Tanis, J A; Dassanayake, B S; Ikeda, T
2013-01-01
The transmission of 1 and 3 MeV protons through a borosilicate straight glass capillary and a tapered glass capillary was investigated. The straight capillary had a diameter of ∼0.18 mm and a length of ∼14.4 mm, while the tapered capillary had an inlet diameter of ∼0.71 mm, an outlet diameter of ∼0.10 mm and a length of ∼28 mm. The results show that the 1 and 3 MeV protons traverse through both samples without energy loss, while the tapered capillary showed better transmission than the straight capillary. (paper)
Simulation and analysis of the transmission properties of curved-straight neutron guide systems
International Nuclear Information System (INIS)
Copley, J.R.D.; Mildner, D.F.R.
1992-01-01
This paper reports that the spatial intensity distribution of neutrons emerging from a curved guide is far from uniform, particularly at short wavelengths, and curved guides are sometimes followed by a straight section of guide to make the intensity distribution more uniform. The behavior of neutrons within curved-straight neutron guide systems is examined using both ray-tracing and analytical approaches to the problem. The intensity distribution within the straight guide tends to wash from one side of the guide to the other. The amplitude of this transverse wave decreases with increasing guide length, and the characteristic length of the wave decreases with increasing neutron wavelength
Leonova, E N; Nagornov, M N; Prokhorenko, A S
2018-01-01
The objective of the present study was to elucidate the specific morphological features of the imprints of blood-soaked straight and wavy head hair. The contact imprints of straight and wavy head hair dirtied with blood were obtained experimentally. The imprints of straight hair were shown to exhibit the elements in the form of the rectilinear and bow-shaped slightly bent stripes. The imprints of wavy hair were shaped as the arches, waves, circles, and a large number of various small elements, such as dashes and commas.
Increased Surface Roughness in Polydimethylsiloxane Films by Physical and Chemical Methods
Directory of Open Access Journals (Sweden)
Jorge Nicolás Cabrera
2017-08-01
Full Text Available Two methods, the first physical and the other chemical, were investigated to modify the surface roughness of polydimethylsiloxane (PDMS films. The physical method consisted of dispersing multi-walled carbon nanotubes (MWCNTs and magnetic cobalt ferrites (CoFe2O4 prior to thermal cross-linking, and curing the composite system in the presence of a uniform magnetic field H. The chemical method was based on exposing the films to bromine vapours and then UV-irradiating. The characterizing techniques included scanning electron microscopy (SEM, energy-dispersive spectroscopy (EDS, Fourier transform infrared (FTIR spectroscopy, optical microscopy, atomic force microscopy (AFM and magnetic force microscopy (MFM. The surface roughness was quantitatively analyzed by AFM. In the physical method, the random dispersion of MWCNTs (1% w/w and magnetic nanoparticles (2% w/w generated a roughness increase of about 200% (with respect to PDMS films without any treatment, but that change was 400% for films cured in the presence of H perpendicular to the surface. SEM, AFM and MFM showed that the magnetic particles always remained attached to the carbon nanotubes, and the effect on the roughness was interpreted as being due to a rupture of dispersion randomness and a possible induction of structuring in the direction of H. In the chemical method, the increase in roughness was even greater (1000%. Wells were generated with surface areas that were close to 100 μm2 and depths of up to 500 nm. The observations of AFM images and FTIR spectra were in agreement with the hypothesis of etching by Br radicals generated by UV on the polymer chains. Both methods induced important changes in the surface roughness (the chemical method generated the greatest changes due to the formation of surface wells, which are of great importance in superficial technological processes.
Walls, N. Eugene; Wisneski, Hope; Kane, Sarah
2013-01-01
Using a sample of 284 sexual minority youth and young adults, this paper examines the relationships between mental health variables, the absence or presence of a gay-straight alliance, and membership status in a gay-straight alliance. The results suggest that the presence of a gay-straight alliance in a school or college, rather than actual…
Plasma discharge in ferritic first wall vacuum vessel of the Hitachi Tokamak HT-2
International Nuclear Information System (INIS)
Abe, Mitsushi; Nakayama, Takeshi; Asano, Katsuhiko; Otsuka, Michio
1997-01-01
A tokamak discharge with ferritic material first wall was tried successfully. The Hitachi Tokamak HT-2 had a stainless steel SUS304 vacuum vessel and modified to have a ferritic plate first wall for experiments to investigate the possibility of ferritic material usage in magnetic fusion devices. The achieved vacuum pressure and times used for discharge cleaning was roughly identical with the stainless steel first wall or the original HT-2. We concluded that ferritic material vacuum vessel is possible for tokamaks. (author)
Dewetting of thin polymer film on rough substrate: II. Experiment
International Nuclear Information System (INIS)
Volodin, Pylyp; Kondyurin, Alexey
2008-01-01
The theory of the dewetting process developed for a model of substrate-film interaction forces was examined by an experimental investigation of the dewetting process of thin polystyrene (PS) films on chemically etched silicon substrates. In the dependence on PS films thickness and silicon roughness, various situations of dewetting were observed as follows: (i) if the wavelength of the substrate roughness is much larger than the critical spinodal wavelength of a film, then spinodal dewetting of the film is observed; (ii) if the wavelength of the substrate roughness is smaller than the critical wavelength of the film and the substrate roughness is larger in comparison with film thickness, then the dewetting due to substrate roughness is observed and the dewetted film patterns repeat the rough substrate structure; (iii) if the wavelength of the substrate roughness is smaller than the critical wavelength of the film and the substrate roughness is small in comparison with the film thickness, then spinodal dewetting proceeds
Sub-Patch Roughness in Earthquake Rupture Investigations
Zielke, Olaf; Mai, Paul Martin
2016-01-01
Fault geometric complexities exhibit fractal characteristics over a wide range of spatial scales (<µm to >km) and strongly affect the rupture process at corresponding scales. Numerical rupture simulations provide a framework to quantitatively investigate the relationship between a fault's roughness and its seismic characteristics. Fault discretization however introduces an artificial lower limit to roughness. Individual fault patches are planar and sub-patch roughness –roughness at spatial scales below fault-patch size– is not incorporated. Does negligence of sub-patch roughness measurably affect the outcome of earthquake rupture simulations? We approach this question with a numerical parameter space investigation and demonstrate that sub-patch roughness significantly modifies the slip-strain relationship –a fundamental aspect of dislocation theory. Faults with sub-patch roughness induce less strain than their planar-fault equivalents at distances beyond the length of a slipping fault. We further provide regression functions that characterize the stochastic effect sub-patch roughness.
Roughness transitions of diamond(100) induced by hydrogen-plasma treatment
Koslowski, B.; Strobel, S.; Wenig, M. J.; Ziemann, P.
To investigate the influence of hydrogen-plasma treatment on diamond(100) surfaces, heavily boron (B)-doped HPHT diamond crystals were mechanically and chemo-mechanically polished, and exposed to a microwave-assisted hydrogen plasma on a time scale of several minutes. The resulting surface morphology was analyzed on macroscopic scales by stylus profilometry (PFM) and on microscopic scales by STM and AFM. The polished samples have a roughness of typically 100 pmrms (PFM), with no obvious anisotropic structures at the surface. After exposure of the B-doped diamond(100) to the H-plasma, the roughness increases dramatically, and pronounced anisotropic structures appear, these being closely aligned with the crystallographic axis' and planes. An exposure for 3 minutes to the plasma leads to an increase of the roughness to 2-4 nmrms (STM), and a `brick-wall' pattern appears, formed by weak cusps running along . Very frequently, the cusps are replaced by `negative' pyramids that are bordered by {11X} facets. After an exposure of an additional 5 minutes, the surface roughness of the B-doped samples increases further to 20-40 nmrms (STM), and frequently exhibits a regular pattern with structures at a characteristic length scale of about 100 nm. Those structures are aligned approximately with and they are faceted with faces of approximately {XX1}. These results will be discussed in terms of strain relaxation, similar to the surface roughening observed on SiGe/Si and anisotropic etching.
Longitudinal relaxation of initially straight flexible and stiff polymers
Dimitrakopoulos, Panagiotis; Dissanayake, Inuka
2004-11-01
The present talk considers the relaxation of a single flexible or stiff polymer chain from an initial straight configuration in a viscous solvent. This problem commonly arises when strong flows are turned off in both industrial and biological applications. The problem is also motivated by recent experiments with single biopolymer molecules relaxing after being fully extended by applied forces as well as by the recent development of micro-devices involving stretched tethered biopolymers. Our results are applicable to a wide array of synthetic polymers such as polyacrylamides, Kevlar and polyesters as well as biopolymers such as DNA, actin filaments, microtubules and MTV. In this talk we discuss the mechanism of the polymer relaxation as was revealed through Brownian Dynamics simulations covering a broad range of time scales and chain stiffness. After the short-time free diffusion, the chain's longitudinal reduction at early intermediate times is shown to constitute a universal behavior for any chain stiffness caused by a quasi-steady relaxation of tensions associated with the deforming action of the Brownian forces. Stiff chains are shown to exhibit a late intermediate-time longitudinal reduction associated with a relaxation of tensions affected by the deforming Brownian and the restoring bending forces. The longitudinal and transverse relaxations are shown to obey different laws, i.e. the chain relaxation is anisotropic at all times. In the talk, we show how from the knowledge of the relaxation mechanism, we can predict and explain the polymer properties including the polymer stress and the solution birefringence. In addition, a generalized stress-optic law is derived valid for any time and chain stiffness. All polymer properties which depend on the polymer length are shown to exhibit two intermediate-time behaviors with the early one to constitute a universal behavior for any chain stiffness. This work was supported in part by the Minta Martin Research Fund. The
Roughness characterization of the galling of metals
Hubert, C.; Marteau, J.; Deltombe, R.; Chen, Y. M.; Bigerelle, M.
2014-09-01
Several kinds of tests exist to characterize the galling of metals, such as that specified in ASTM Standard G98. While the testing procedure is accurate and robust, the analysis of the specimen's surfaces (area=1.2 cm) for the determination of the critical pressure of galling remains subject to operator judgment. Based on the surface's topography analyses, we propose a methodology to express the probability of galling according to the macroscopic pressure load. After performing galling tests on 304L stainless steel, a two-step segmentation of the S q parameter (root mean square of surface amplitude) computed from local roughness maps (100 μ m× 100 μ m) enables us to distinguish two tribological processes. The first step represents the abrasive wear (erosion) and the second one the adhesive wear (galling). The total areas of both regions are highly relevant to quantify galling and erosion processes. Then, a one-parameter phenomenological model is proposed to objectively determine the evolution of non-galled relative area A e versus the pressure load P, with high accuracy ({{A}e}=100/(1+a{{P}2}) with a={{0.54}+/- 0.07}× {{10}-3} M P{{a}-2} and with {{R}2}=0.98). From this model, the critical pressure of galling is found to be equal to 43MPa. The {{S}5 V} roughness parameter (the five deepest valleys in the galled region's surface) is the most relevant roughness parameter for the quantification of damages in the ‘galling region’. The significant valleys’ depths increase from 10 μm-250 μm when the pressure increases from 11-350 MPa, according to a power law ({{S}5 V}=4.2{{P}0.75}, with {{R}2}=0.93).
Robust surface roughness indices and morphological interpretation
Trevisani, Sebastiano; Rocca, Michele
2016-04-01
Geostatistical-based image/surface texture indices based on variogram (Atkison and Lewis, 2000; Herzfeld and Higginson, 1996; Trevisani et al., 2012) and on its robust variant MAD (median absolute differences, Trevisani and Rocca, 2015) offer powerful tools for the analysis and interpretation of surface morphology (potentially not limited to solid earth). In particular, the proposed robust index (Trevisani and Rocca, 2015) with its implementation based on local kernels permits the derivation of a wide set of robust and customizable geomorphometric indices capable to outline specific aspects of surface texture. The stability of MAD in presence of signal noise and abrupt changes in spatial variability is well suited for the analysis of high-resolution digital terrain models. Moreover, the implementation of MAD by means of a pixel-centered perspective based on local kernels, with some analogies to the local binary pattern approach (Lucieer and Stein, 2005; Ojala et al., 2002), permits to create custom roughness indices capable to outline different aspects of surface roughness (Grohmann et al., 2011; Smith, 2015). In the proposed poster, some potentialities of the new indices in the context of geomorphometry and landscape analysis will be presented. At same time, challenges and future developments related to the proposed indices will be outlined. Atkinson, P.M., Lewis, P., 2000. Geostatistical classification for remote sensing: an introduction. Computers & Geosciences 26, 361-371. Grohmann, C.H., Smith, M.J., Riccomini, C., 2011. Multiscale Analysis of Topographic Surface Roughness in the Midland Valley, Scotland. IEEE Transactions on Geoscience and Remote Sensing 49, 1220-1213. Herzfeld, U.C., Higginson, C.A., 1996. Automated geostatistical seafloor classification - Principles, parameters, feature vectors, and discrimination criteria. Computers and Geosciences, 22 (1), pp. 35-52. Lucieer, A., Stein, A., 2005. Texture-based landform segmentation of LiDAR imagery
Traceability of optical roughness measurements on polymers
DEFF Research Database (Denmark)
De Chiffre, Leonardo; Gasparin, Stefania; Carli, Lorenzo
2008-01-01
-focus instrument, and a confocal microscope. Using stylus measurements as reference, parameter settings on the optical instruments were optimised and residual noise reduced by low pass filtering. Traceability of optical measurements could be established with expanded measuring uncertainties (k=2) of 4......An experimental investigation on surface roughness measurements on plastics was carried out with the objective of developing a methodology to achieve traceability of optical instruments. A ground steel surface and its replicas were measured using a stylus instrument, an optical auto......% for the auto-focus instrument and 10% for confocal microscope....
Wave scattering from statistically rough surfaces
Bass, F G; ter Haar, D
2013-01-01
Wave Scattering from Statistically Rough Surfaces discusses the complications in radio physics and hydro-acoustics in relation to wave transmission under settings seen in nature. Some of the topics that are covered include radar and sonar, the effect of variations in topographic relief or ocean waves on the transmission of radio and sound waves, the reproduction of radio waves from the lower layers of the ionosphere, and the oscillations of signals within the earth-ionosphere waveguide. The book begins with some fundamental idea of wave transmission theory and the theory of random processes a
International Nuclear Information System (INIS)
Stoessel, A.; Boulanger, G.; Furlan, J.; Mogavero, R.
1981-09-01
This non-destructive testing unit inspects the cladding tubes for the SUPER-PHENIX fast neutron reactor. The quality level demanded for these tubes, as well as their number, required designing an installation that combined high performance with a great testing rate and complete automation. The testing is effected under immersion by means of six transducers, focused in line, working at 30 MHz. The tubes are numbered on an automatic rig; marking is by dark rings obtained by superficial electrolysis of the tube and regularly distributed on the abscissa; the quality of the tube is not affected by this. The advantage of this numbering system is that it enables the tubes to be fed to the test set in any order. An acquisition unit, constituted of a microprocessor, a semi-graphical printer and a double floppy disk unit, makes it possible to enter, edit and store the information for each tube [fr
49 CFR 238.119 - Rim-stamped straight-plate wheels.
2010-10-01
... input to the wheel during braking. (b) A rim-stamped straight-plate wheel shall not be used as a... that is periodically tread-braked for a short duration by automatic circuitry for the sole purpose of...
Ring energy selection and extra long straight sections for the Advanced Photon Source
International Nuclear Information System (INIS)
1987-04-01
Recommended criteria are given for the performance of Advanced Photon Source (APS), taking into consideration undulator tunability criteria and their relationship to the storage ring energy and undulator gap, length of straight sections
International Nuclear Information System (INIS)
Harrach, Michael F.; Drossel, Barbara
2014-01-01
We perform molecular dynamics simulations to observe the structure and dynamics of water using different water models (TIP3P, TIP4P, TIP5P) at ambient conditions, constrained by planar walls, which are either modeled by smooth potentials or regular atomic lattices, imitating the honeycomb-structure of graphene. We implement walls of different hydroaffinity, different lattice constant, and different types of interaction with the water molecules. We find that in the hydrophobic regime the smooth wall generally represents a good abstraction of the atomically rough walls, while in the hydrophilic regime there are noticeable differences in structure and dynamics between all stages of wall roughness. For a small lattice constant however the smooth and the atomically rough wall still share a number of structural and dynamical similarities. Out of the three water models, TIP5P water shows the largest degree of tetrahedral ordering and is often the one that is least perturbed by the presence of the wall
Urban roughness mapping validation techniques and some first results
Bottema, M; Mestayer, PG
1998-01-01
Because of measuring problems related to evaluation of urban roughness parameters, a new approach using a roughness mapping tool has been tested: evaluation of roughness length z(o) and zero displacement z(d) from cadastral databases. Special attention needs to be given to the validation of the
Procedure and applications of combined wheel/rail roughness measurement
Dittrich, M.G.
2009-01-01
Wheel-rail roughness is known to be the main excitation source of railway rolling noise. Besides the already standardised method for direct roughness measurement, it is also possible to measure combined wheel-rail roughness from vertical railhead vibration during a train pass-by. This is a different
Rough sets applied in sublattices and ideals of lattices
Directory of Open Access Journals (Sweden)
R. Ameri
2015-12-01
Full Text Available The purpose of this paper is the study of rough hyperlattice. In this regards we introduce rough sublattice and rough ideals of lattices. We will proceed by obtaining lower and upper approximations in these lattices.
Use of roughness maps in visualisation of surfaces
DEFF Research Database (Denmark)
Seitavuopio, Paulus; Rantanen, Jukka; Yliruusi, Jouko
2005-01-01
monohydrate, theophylline anhydrate, sodium chloride and potassium chloride. The roughness determinations were made by a laser profilometer. The new matrix method gives detailed roughness maps, which are able to show local variations in surface roughness values and provide an illustrative picture...
ROMI 4.0: Updated Rough Mill Simulator
Timo Grueneberg; R. Edward Thomas; Urs Buehlmann
2012-01-01
In the secondary hardwood industry, rough mills convert hardwood lumber into dimension parts for furniture, cabinets, and other wood products. ROMI 4.0, the US Department of Agriculture Forest Service's ROugh-MIll simulator, is a software package designed to simulate the cut-up of hardwood lumber in rough mills in such a way that a maximum possible component yield...
Rough sets selected methods and applications in management and engineering
Peters, Georg; Ślęzak, Dominik; Yao, Yiyu
2012-01-01
Introduced in the early 1980s, Rough Set Theory has become an important part of soft computing in the last 25 years. This book provides a practical, context-based analysis of rough set theory, with each chapter exploring a real-world application of Rough Sets.
7 CFR 868.201 - Definition of rough rice.
2010-01-01
... 7 Agriculture 7 2010-01-01 2010-01-01 false Definition of rough rice. 868.201 Section 868.201... FOR CERTAIN AGRICULTURAL COMMODITIES United States Standards for Rough Rice Terms Defined § 868.201 Definition of rough rice. Rice (Oryza sativa L.) which consists of 50 percent or more of paddy kernels (see...
Flow visualization and relative permeability measurements in rough-walled fractures
International Nuclear Information System (INIS)
Persoff, P.; Pruess, K.
1993-01-01
Two-phase (gas-liquid) flow experiments were done in a natural rock fracture and transparent replicas of natural fractures. Liquid was injected at constant volume flow rate, and gas was injected at either constant mass flow rate or constant pressure. When gas was injected at constant mass flow rate, the gas inlet pressure, and inlet and outlet capillary pressures, generally did not reach steady state but cycled irregularly. Flow visualization showed that this cycling was due to repeated blocking and unblocking of gas flow paths by liquid. Relative permeabilities calculated from flow rate and pressure data show that the sum of the relative permeabilities of the two phases is much less than 1, indicating that each phase interferes strongly with the flow of the other. Comparison of the relative permeability curves with typical curves for porous media (Corey curves) show that the phase interference is stronger in fractures than in typical porous media
The Thermal And Hydrodynamic Behavior of Thick, Rough-Wall, Turbulent Boundary Layers,
1979-08-01
Nikuradse, J., "Stromungsgesetze in rauhen Rohren," VDI Forschungsschaft, No. 361, 1933, English translation, NACA-TM 1292, 1950. 168 I I Orlando, A. F...used. 2048 data samples were takeu from the signal, providing a maximum spectral resolution of 9.77 Hz. The digital samples were processed using a
International Nuclear Information System (INIS)
Mauget, C.; Benoit, G.; Stalport, G.
1993-01-01
Straight tube heat exchangers are used as steam generators in nuclear reactors such as in fast neutron nuclear power plants; elevated and highly variable temperatures induce very high thermal expansion constraints in these long straight tubes. In order to avoid the expansion problems, an expansion bellow is disposed between the heat exchanger and the collector tubular plate in such a way that the bundle differential expansions may be absorbed
Manufacture of the straight section chambers for the SPring-8 storage ring
International Nuclear Information System (INIS)
Watanabe, K.; Saeki, H.; Sakaue, H.; Ohkuma, H.; Be, S.H.; Oishi, M.; Tuchiya, M.; Nishidono, T.
1995-01-01
To carry out the performance test of the vacuum system, we manufactured three different straight section chambers prior to the manufacture of the 48 cell full scale vacuum systems. One of three straight section chambers contains only downstream end absorber, while the other two contain a downstream end absorber, upstream end bellows and a photon beam extraction duct. In this paper, the manufacture of these chambers and their assemblies are described in detail. (author). 1 ref., 3 figs., 3 tabs
Estimation of roughness lengths and flow separation over compound bedforms in a natural-tidal inlet
DEFF Research Database (Denmark)
Lefebvre, Alice; Ernstsen, Verner Brandbyge; Winter, Christian
2013-01-01
was found to underestimate the length of the flow separation zone of the primary bedforms. A better estimation of the presence and shape of the flow separation zone over complex bedforms in a tidal environment still needs to be determined; in particular the relationship between flow separation zone......The hydraulic effect of asymmetric compound bedforms on tidal currents was assessed from field measurements of flow velocity in the Knudedyb tidal inlet, Denmark. Large asymmetric bedforms with smaller superimposed ones are a common feature of sandy shallow water environments and are known to act...... as hydraulic roughness elements in dependence with flow direction. The presence of a flow separation zone on the bedform lee was estimated through analysis of the measured velocity directions and the calculation of the flow separation line. The Law of the Wall was used to calculate roughness lengths and shear...
Rough viscoelastic sliding contact: Theory and experiments
Carbone, G.; Putignano, C.
2014-03-01
In this paper, we show how the numerical theory introduced by the authors [Carbone and Putignano, J. Mech. Phys. Solids 61, 1822 (2013), 10.1016/j.jmps.2013.03.005] can be effectively employed to study the contact between viscoelastic rough solids. The huge numerical complexity is successfully faced up by employing the adaptive nonuniform mesh developed by the authors in Putignano et al. [J. Mech. Phys. Solids 60, 973 (2012), 10.1016/j.jmps.2012.01.006]. Results mark the importance of accounting for viscoelastic effects to correctly simulate the sliding rough contact. In detail, attention is, first, paid to evaluate the viscoelastic dissipation, i.e., the viscoelastic friction. Fixed the sliding speed and the normal load, friction is completely determined. Furthermore, since the methodology employed in the work allows to study contact between real materials, a comparison between experimental outcomes and numerical prediction in terms of viscoelastic friction is shown. The good agreement seems to validate—at least partially—the presented methodology. Finally, it is shown that viscoelasticity entails not only the dissipative effects previously outlined, but is also strictly related to the anisotropy of the contact solution. Indeed, a marked anisotropy is present in the contact region, which results stretched in the direction perpendicular to the sliding speed. In the paper, the anisotropy of the deformed surface and of the contact area is investigated and quantified.
Russell, Eric M; DelPriore, Danielle J; Butterfield, Max E; Hill, Sarah E
2013-02-09
Although research has made progress in elucidating the benefits exchanged within same- and opposite-sex friendships formed between heterosexual men and women, it is less clear why straight women and gay men form close relationships with one another. The current experiments begin to address this question by exploring a potential benefit hypothesized to be uniquely available to straight women and gay men in the context of these friendships: trustworthy mating advice. Experiment 1 revealed that straight women perceive mating-relevant advice from a gay man to be more trustworthy than similar advice offered by a straight man or woman. Experiment 2 demonstrated that gay men perceive mating advice offered by a straight woman to be more trustworthy than advice offered by a lesbian woman or another gay man. Overall, the results provide initial experimental evidence that relationships between gay men and straight women may be characterized by a mutual exchange of mating-relevant benefits in the absence of sexual interest or competition.
Wu, Hui; San, Ka-Yiu
2014-11-01
Free fatty acids (FFAs) can be used as precursors for the production of biofuels or chemicals. Different composition of FFAs will be useful for further modification of the biofuel/biochemical quality. Microbial biosynthesis of even chain FFAs can be achieved by introducing an acyl-acyl carrier protein thioesterase gene into E. coli. In this study, odd straight medium chain FFAs production was investigated by using metabolic engineered E. coli carrying acyl-ACP thioesterase (TE, Ricinus communis), propionyl-CoA synthase (Salmonella enterica), and β-ketoacyl-acyl carrier protein synthase III (four different sources) with supplement of extracellular propionate. By using these metabolically engineered E. coli, significant quantity of C13 and C15 odd straight-chain FFAs could be produced from glucose and propionate. The highest concentration of total odd straight chain FFAs attained was 1205 mg/L by the strain HWK201 (pXZ18, pBHE2), and 85% of the odd straight chain FFAs was C15. However, the highest percentage of odd straight chain FFAs was achieved by the strain HWK201 (pXZ18, pBHE3) of 83.2% at 48 h. This strategy was also applied successfully in strains carrying different TE, such as the medium length acyl-ACP thioesterase gene from Umbellularia californica. C11 and C13 became the major odd straight-chain FFAs. © 2014 Wiley Periodicals, Inc.
Directory of Open Access Journals (Sweden)
Eric M. Russell
2013-01-01
Full Text Available Although research has made progress in elucidating the benefits exchanged within same- and opposite-sex friendships formed between heterosexual men and women, it is less clear why straight women and gay men form close relationships with one another. The current experiments begin to address this question by exploring a potential benefit hypothesized to be uniquely available to straight women and gay men in the context of these friendships: trustworthy mating advice. Experiment 1 revealed that straight women perceive mating-relevant advice from a gay man to be more trustworthy than similar advice offered by a straight man or woman. Experiment 2 demonstrated that gay men perceive mating advice offered by a straight woman to be more trustworthy than advice offered by a lesbian woman or another gay man. Overall, the results provide initial experimental evidence that relationships between gay men and straight women may be characterized by a mutual exchange of mating-relevant benefits in the absence of sexual interest or competition.
Directory of Open Access Journals (Sweden)
Süleyman Demircan
2015-12-01
Full Text Available AIM:To compare the intraoperative performance and postoperative outcomes after microcoaxial torsional phacoemulsification using the straight and the curved phacotip configurations.METHODS:Cataracts were treated using 2.2mm microcoaxial transversal phacoemulsification with either a 30°straight or 30° curved phaco tip. Intraoperative measurements analyzed included the average ultrasound(U/Spower, the total phacoemulsification time, and the effective phacoemulsification time(EPT. The central endothelial cell density(ECDand the central corneal thickness(CCTwere evaluated preoperatively and postoperatively at 1, 7 and 30d after surgery using noncontact specular microscopy. RESULTS:The study enrolled a total of 190 eyes(190 patients, 95 eyes in the curved tip group and 95 eyes in straight tip group. Intraoperative measurements showed significantly reduced total phacoemulsification time, and EPT in the curved-tip group, compared to the straight-tip group(Pst-3rd quartilesand 18.0(9.0-30.0s in curved-tip group, and 38.8(16.5-73.5s and 26.0(11.0-49.0s in the straight-tip group, respectively. CONCLUSION:Transversal phacoemulsification performed with a curved tip provided more effective lens removal with a less total UST and EPT in all grades, except for grades IV, compared to a straight tip.
Inviscid Wall-Modeled Large Eddy Simulations for Improved Efficiency
Aikens, Kurt; Craft, Kyle; Redman, Andrew
2015-11-01
The accuracy of an inviscid flow assumption for wall-modeled large eddy simulations (LES) is examined because of its ability to reduce simulation costs. This assumption is not generally applicable for wall-bounded flows due to the high velocity gradients found near walls. In wall-modeled LES, however, neither the viscous near-wall region or the viscous length scales in the outer flow are resolved. Therefore, the viscous terms in the Navier-Stokes equations have little impact on the resolved flowfield. Zero pressure gradient flat plate boundary layer results are presented for both viscous and inviscid simulations using a wall model developed previously. The results are very similar and compare favorably to those from another wall model methodology and experimental data. Furthermore, the inviscid assumption reduces simulation costs by about 25% and 39% for supersonic and subsonic flows, respectively. Future research directions are discussed as are preliminary efforts to extend the wall model to include the effects of unresolved wall roughness. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1053575. Computational resources on TACC Stampede were provided under XSEDE allocation ENG150001.
Bifurcation parameters of a reflected shock wave in cylindrical channels of different roughnesses
Penyazkov, O.; Skilandz, A.
2018-03-01
To investigate the effect of bifurcation on the induction time in cylindrical shock tubes used for chemical kinetic experiments, one should know the parameters of the bifurcation structure of a reflected shock wave. The dynamics and parameters of the shock wave bifurcation, which are caused by reflected shock wave-boundary layer interactions, are studied experimentally in argon, in air, and in a hydrogen-nitrogen mixture for Mach numbers M = 1.3-3.5 in a 76-mm-diameter shock tube without any ramp. Measurements were taken at a constant gas density behind the reflected shock wave. Over a wide range of experimental conditions, we studied the axial projection of the oblique shock wave and the pressure distribution in the vicinity of the triple Mach configuration at 50, 150, and 250 mm from the endwall, using side-wall schlieren and pressure measurements. Experiments on a polished shock tube and a shock tube with a surface roughness of 20 {μ }m Ra were carried out. The surface roughness was used for initiating small-scale turbulence in the boundary layer behind the incident shock wave. The effect of small-scale turbulence on the homogenization of the transition zone from the laminar to turbulent boundary layer along the shock tube perimeter was assessed, assuming its influence on a subsequent stabilization of the bifurcation structure size versus incident shock wave Mach number, as well as local flow parameters behind the reflected shock wave. The influence of surface roughness on the bifurcation development and pressure fluctuations near the wall, as well as on the Mach number, at which the bifurcation first develops, was analyzed. It was found that even small additional surface roughness can lead to an overshoot in pressure growth by a factor of two, but it can stabilize the bifurcation structure along the shock tube perimeter.
Mental constructs and the cognitive reconstruction of the Berlin wall.
Tijus, C A; Santolini, A
1996-07-01
In this study of how to change people's conceptions of certain facts (i.e., the position of the Berlin Wall), a surprising psychological phenomenon was discovered. In the trial test, instead of designing a wall to enclose West Berlin, most people described and drew a short and straight wall that divided the city from north to south. Two methods were created, based on two general information-processing components involved in problem solving, to study how people might repair their misconceptions by themselves. The do-it-yourself method consisted of providing people with the task of thinking about how to build the wall and then drawing it, instead of just asking them to draw it. The distance-to-goal evaluation method consisted of asking the participants how the wall they had drawn would actually prevent passage from East Germany to West Berlin. The results showed that both methods had important effects in repairing misconceptions, but improvement in performance with the distance-to-goal method was less significant for those participants who were first provided the task of thinking about how to build the wall. These findings are consistent with the hypothesis that awareness of functional properties plays an important role in structuring and restructuring mental constructs.
Amyloidosis - abdominal wall fat pad biopsy; Abdominal wall biopsy; Biopsy - abdominal wall fat pad ... is the most common method of taking an abdominal wall fat pad biopsy . The health care provider cleans the ...
Energy Technology Data Exchange (ETDEWEB)
Meier, W R
2011-02-24
The key feature of liquid wall chambers is the use of a renewable liquid layer to protect chamber structures from target emissions. Two primary options have been proposed and studied: wetted wall chambers and thick liquid wall (TLW) chambers. With wetted wall designs, a thin layer of liquid shields the structural first wall from short ranged target emissions (x-rays, ions and debris) but not neutrons. Various schemes have been proposed to establish and renew the liquid layer between shots including flow-guiding porous fabrics (e.g., Osiris, HIBALL), porous rigid structures (Prometheus) and thin film flows (KOYO). The thin liquid layer can be the tritium breeding material (e.g., flibe, PbLi, or Li) or another liquid metal such as Pb. TLWs use liquid jets injected by stationary or oscillating nozzles to form a neutronically thick layer (typically with an effective thickness of {approx}50 cm) of liquid between the target and first structural wall. In addition to absorbing short ranged emissions, the thick liquid layer degrades the neutron flux and energy reaching the first wall, typically by {approx}10 x x, so that steel walls can survive for the life of the plant ({approx}30-60 yrs). The thick liquid serves as the primary coolant and tritium breeding material (most recent designs use flibe, but the earliest concepts used Li). In essence, the TLW places the fusion blanket inside the first wall instead of behind the first wall.
Roughness as classicality indicator of a quantum state
Lemos, Humberto C. F.; Almeida, Alexandre C. L.; Amaral, Barbara; Oliveira, Adélcio C.
2018-03-01
We define a new quantifier of classicality for a quantum state, the Roughness, which is given by the L2 (R2) distance between Wigner and Husimi functions. We show that the Roughness is bounded and therefore it is a useful tool for comparison between different quantum states for single bosonic systems. The state classification via the Roughness is not binary, but rather it is continuous in the interval [ 0 , 1 ], being the state more classic as the Roughness approaches to zero, and more quantum when it is closer to the unity. The Roughness is maximum for Fock states when its number of photons is arbitrarily large, and also for squeezed states at the maximum compression limit. On the other hand, the Roughness approaches its minimum value for thermal states at infinite temperature and, more generally, for infinite entropy states. The Roughness of a coherent state is slightly below one half, so we may say that it is more a classical state than a quantum one. Another important result is that the Roughness performs well for discriminating both pure and mixed states. Since the Roughness measures the inherent quantumness of a state, we propose another function, the Dynamic Distance Measure (DDM), which is suitable for measure how much quantum is a dynamics. Using DDM, we studied the quartic oscillator, and we observed that there is a certain complementarity between dynamics and state, i.e. when dynamics becomes more quantum, the Roughness of the state decreases, while the Roughness grows as the dynamics becomes less quantum.
Effect of Blade Roughness on Transition and Wind Turbine Performance.
Energy Technology Data Exchange (ETDEWEB)
Ehrmann, Robert S. [Texas A & M Univ., College Station, TX (United States); White, E. B. [Texas A & M Univ., College Station, TX (United States)
2015-09-01
The real-world effect of accumulated surface roughness on wind-turbine power production is not well understood. To isolate specific blade roughness features and test their effect, field measurements of turbine-blade roughness were made and simulated on a NACA 633-418 airfoil in a wind tunnel. Insect roughness, paint chips, and erosion were characterized then manufactured. In the tests, these roughness configurations were recreated as distributed roughness, a forward-facing step, and an eroded leading edge. Distributed roughness was tested in three heights and five densities. Chord Reynolds number was varied between 0:8 to 4:8 × 10^{6}. Measurements included lift, drag, pitching moment, and boundary-layer transition location. Results indicate minimal effect from paint-chip roughness. As distributed roughness height and density increase, the lift-curve slope, maximum lift, and lift-to-drag ratio decrease. As Reynolds number increases, natural transition is replaced by bypass transition. The critical roughness Reynolds number varies between 178 to 318, within the historical range. At a chord Reynolds number of 3:2 × 10^{6}, the maximum lift-to-drag ratio decreases 40% for 140 μm roughness, corresponding to a 2.3% loss in annual energy production. Simulated performance loss compares well to measured performance loss of an in-service wind turbine.
Barros, Julio; Schultz, Michael; Flack, Karen
2016-11-01
Engineering systems are affected by surface roughness which cause an increase in drag leading to significant performance penalties. One important question is how to predict frictional drag purely based upon surface topography. Although significant progress has been made in recent years, this has proven to be challenging. The present work takes a systematic approach by generating surface roughness in which surfaces parameters, such as rms , skewness, can be controlled. Surfaces were produced using the random Fourier modes method with enforced power-law spectral slopes. The surfaces were manufactured using high resolution 3D-printing. In this study three surfaces with constant amplitude and varying slope, P, were investigated (P = - 0 . 5 , - 1 . 0 , - 1 . 5). Skin-friction measurements were conducted in a high Reynolds number turbulent channel flow facility, covering a wide range of Reynolds numbers, from hydraulic-smooth to fully-rough regimes. Results show that some long wavelength roughness scales do not contribute significantly to the frictional drag, thus highlighting the need for filtering in the calculation of surface statistics. Upon high-pass filtering, it was found that krms is highly correlated with the measured ks.
Thermalhydraulic experiments with a cluster of 19 rods roughened by a novel type of roughness
International Nuclear Information System (INIS)
Rehme, K.; Kernforschungszentrum Karlsruhe G.m.b.H.
1981-02-01
Distributions of temperature and pressure were measured on cluster of 19 electrically heated tubes. 400 thermocouples were used for temperature measurements. The tubes were partly roughened by a novel type of roughness with a thermal performance superior to that of transverse ribs. The experiments bot with helium and nitrogen as coolants covered a range of Reynolds numbers between 450 and 1.8 x 10 5 . The maximum linear rod power achived was 43 kWm -1 , the maximum measured wall temperature 1271 K (998 0 C). The report contains the description of the test section together with all tabulated results. (orig.) [de
International Nuclear Information System (INIS)
Blanco, Rosa L.D.; Moeller, Sergio V.
1995-01-01
The experimental study of the temperature fluctuation in a circular section pipe with artificial roughness is presented. Micro thermocouples are applied for the measurements of the temperature and its fluctuations. Auto spectral density functions as well as autocorrelation functions were obtained by means of a Fourier Analyzer. Results compared to measurements performed in a smooth pipe, show that the turbulent scales for the temperature fluctuations increase in the regions near the walls, without significant changes in the regions near the center of the pipe. (author). 15 refs, 10 figs
Coupled Dzyaloshinskii walls and their current-induced dynamics by the spin Hall effect
Energy Technology Data Exchange (ETDEWEB)
Martínez, Eduardo, E-mail: edumartinez@usal.es [Dpto. de Fisica Aplicada, Universidad de Salamanca, Plaza de los Caídos s/n, E-37008 Salamanca (Spain); Alejos, Óscar [Dpto. de Electricidad y Electrónica, Universidad de Valladolid, Paseo de Belén, 7, E-47011 Valladolid (Spain)
2014-07-14
The nucleation of domain walls in ultrathin ferromagnetic/heavy-metal bilayers is studied by means of micromagnetic simulations. In the presence of interfacial Dzyaloshinskii-Moriya interaction, the nucleated walls naturally adopt a homochiral configuration with internal magnetization pointing antiparallely. The interaction between these walls was analyzed and described in terms of a classical dipolar force between the magnetic moments of the walls, which couples their dynamics. Additionally, the current-induced motion of two homochiral walls in the presence of longitudinal fields was also studied by means of a simple one-dimensional model and micromagnetic modeling, considering both one free-defect strip and another one with random edge roughness. It is evidenced that in the presence of pinning due to edge roughness, the in-plane longitudinal field introduces an asymmetry in the current-induced depinning, in agreement with recent experimental results.
Coupled Dzyaloshinskii walls and their current-induced dynamics by the spin Hall effect
International Nuclear Information System (INIS)
Martínez, Eduardo; Alejos, Óscar
2014-01-01
The nucleation of domain walls in ultrathin ferromagnetic/heavy-metal bilayers is studied by means of micromagnetic simulations. In the presence of interfacial Dzyaloshinskii-Moriya interaction, the nucleated walls naturally adopt a homochiral configuration with internal magnetization pointing antiparallely. The interaction between these walls was analyzed and described in terms of a classical dipolar force between the magnetic moments of the walls, which couples their dynamics. Additionally, the current-induced motion of two homochiral walls in the presence of longitudinal fields was also studied by means of a simple one-dimensional model and micromagnetic modeling, considering both one free-defect strip and another one with random edge roughness. It is evidenced that in the presence of pinning due to edge roughness, the in-plane longitudinal field introduces an asymmetry in the current-induced depinning, in agreement with recent experimental results.
Influence of surface roughness of a desert
Sud, Y. C.; Smith, W. E.
1984-01-01
A numerical simulation study, using the current GLAS climate GCM, was carried out to examine the influence of low bulk aerodynamic drag parameter in the deserts. The results illustrate the importance of yet another feedback effect of a desert on itself, that is produced by the reduction in surface roughness height of land once the vegetation dies and desert forms. Apart from affecting the moisture convergence, low bulk transport coefficients of a desert lead to enhanced longwave cooling and sinking which together reduce precipitation by Charney's (1975) mechanism. Thus, this effect, together with albedo and soil moisture influence, perpetuate a desert condition through its geophysical feedback effect. The study further suggests that man made deserts is a viable hypothesis.
Numerical and Experimental Study on Confinement in Y-Shaped Post Wall Branching Waveguide
Directory of Open Access Journals (Sweden)
Hiroshi Maeda
2014-01-01
Full Text Available Post wall waveguides consist of dielectric or metallic cylinders for microwave around 4 GHz were experimentally and numerically investigated. The structure attracts interests for application of transmission circuit for three-dimensionally integrated planar circuit in millimeter wavelength. In straight waveguide with dielectric cylinders, confinement of microwave is poor, when the post wall was composed of a pair of single row of cylinders. The confinement was improved as increase of rows of post wall. In metallic cylinders, microwave was well confined even when a pair of single row of cylinders composed the waveguide. After confirming confinement of the electromagnetic field, Y-shaped branches of post wall waveguide consisted of dielectric cylinders for microwave were similarly investigated for dielectric rods. The confinement was also improved by increase of post wall up to 3 layers. These results are applicable for fundamental design and fabrication of integrated circuit for microwave and millimeter wave.
International Nuclear Information System (INIS)
Ahn, Seok Hwan; Nam, Ki Woo; Kim, Seon Jin; Kim, Jin Hwan; Kim, Hyun Soo; Do, Jae Yoon
2003-01-01
Fracture behaviors of pipes with local wall thinning are very important for the integrity of nuclear power plant. In pipes of energy plants, sometimes, the local wall thinning may result from severe Erosion-Corrosion (E/C) damage. However, the effects of local wall thinning on strength and fracture behaviors of piping system were not well studied. In this paper, the monotonic bending tests were performed of full-scale carbon steel pipes with local wall thinning. A monotonic bending load was applied to straight pipe specimens by four-point loading at ambient temperature without internal pressure. From the tests, fracture behaviors and fracture strength of locally thinned pipe were manifested systematically. The observed failure modes were divided into four types; ovalization, crack initiation/growth after ovalization, local buckling and crack initiating/growth after local buckling. Also, the strength and the allowable limit of piping system with local wall thinning were evaluated
Sams, E. W.
1952-01-01
An investigation of forced-convection heat transfer and associated pressure drops was conducted with air flowing through electrically heated Inconel tubes having various degrees of square-thread-type roughness, an inside diameter of 1/2 inch, and a length of 24 inches. were obtained for tubes having conventional roughness ratios (height of thread/radius of tube) of 0 (smooth tube), 0.016, 0.025, and 0.037 over ranges of bulk Reynolds numbers up to 350,000, average inside-tube-wall temperatures up to 1950deg R, and heat-flux densities up to 115,000 Btu per hour per square foot. Data The experimental data showed that both heat transfer and friction increased with increase in surface roughness, becoming more pronounced with increase in Reynolds number; for a given roughness, both heat transfer and friction were also influenced by the tube wall-to-bulk temperature ratio. Good correlation of the heat-transfer data for all the tubes investigated was obtained by use of a modification of the conventional Nusselt correlation parameters wherein the mass velocity in the Reynolds number was replaced by the product of air density evaluated at the average film temperature and the so-called friction velocity; in addition, the physical properties of air were evaluated at the average film temperature. The isothermal friction data for the rough tubes, when plotted in the conventional manner, resulted in curves similar to those obtained by other investigators; that is, the curve for a given roughness breaks away from the Blasius line (representing turbulent flow in smooth tubes) at some value of Reynolds number, which decreases with increase in surface roughness, and then becomes a horizontal line (friction coefficient independent of Reynolds number). A comparison of the friction data for the rough tubes used herein indicated that the conventional roughness ratio is not an adequate measure of relative roughness for tubes having a square-thread-type element. The present data, as well
Additional Quadrupoles At Center Of Long Straights In The NSLS-II Lattice
International Nuclear Information System (INIS)
Lin, F.; Bengtsson, J.; Guo, W.; Krinsky, S.; Li, Y.; Yang, L.
2011-01-01
The NSLS-II storage ring lattice is comprised of 30 DBA cells arranged in 15 superperiods. There are 15 long straight sections (9.3m) for injection, RF and insertion devices and 15 shorter straights (6.6m) for insertion devices. In the baseline lattice, the short straights have small horizontal and vertical beta functions but the long straights have large horizontal beta function optimized for injection. In this paper, we explore the possibility of installing additional quadrupoles at the center of selected long straight sections in order to provide two low-beta source locations for undulators in the same straight. The required modification to the linear lattice is discussed as well as the preservation of adequate dynamic aperture required for good injection efficiency and adequate Touschek lifetime. This paper discusses the possibility of producing two low-beta source locations for optimum brightness of undulators in the long straights of NSLS-II lattice by installing additional quadrupoles at the center. The linear optics is optimized to satisfy the requirements of lattice function and properties. Nonlinear optimization for a lattice with working point at (37.16, 17.22) is performed. Considering the magnets misalignment errors and physical apertures, we calculate the frequency maps and plot the tune footprint. The results show that the modified high-low beta function lattice can achieve a modest dynamic aperture in this preliminary study. Further work will continue to expand the dynamic aperture to meet the requirement of good injection efficiency and sufficient Touschek lifetime.
Urban Aerodynamic Roughness Length Mapping Using Multitemporal SAR Data
Directory of Open Access Journals (Sweden)
Fengli Zhang
2017-01-01
Full Text Available Aerodynamic roughness is very important to urban meteorological and climate studies. Radar remote sensing is considered to be an effective means for aerodynamic roughness retrieval because radar backscattering is sensitive to the surface roughness and geometric structure of a given target. In this paper, a methodology for aerodynamic roughness length estimation using SAR data in urban areas is introduced. The scale and orientation characteristics of backscattering of various targets in urban areas were firstly extracted and analyzed, which showed great potential of SAR data for urban roughness elements characterization. Then the ground truth aerodynamic roughness was calculated from wind gradient data acquired by the meteorological tower using fitting and iterative method. And then the optimal dimension of the upwind sector for the aerodynamic roughness calculation was determined through a correlation analysis between backscattering extracted from SAR data at various upwind sector areas and the aerodynamic roughness calculated from the meteorological tower data. Finally a quantitative relationship was set up to retrieve the aerodynamic roughness length from SAR data. Experiments based on ALOS PALSAR and COSMO-SkyMed data from 2006 to 2011 prove that the proposed methodology can provide accurate roughness length estimations for the spatial and temporal analysis of urban surface.
Roughness coefficient and its uncertainty in gravel-bed river
Directory of Open Access Journals (Sweden)
Ji-Sung Kim
2010-06-01
Full Text Available Manning's roughness coefficient was estimated for a gravel-bed river reach using field measurements of water level and discharge, and the applicability of various methods used for estimation of the roughness coefficient was evaluated. Results show that the roughness coefficient tends to decrease with increasing discharge and water depth, and over a certain range it appears to remain constant. Comparison of roughness coefficients calculated by field measurement data with those estimated by other methods shows that, although the field-measured values provide approximate roughness coefficients for relatively large discharge, there seems to be rather high uncertainty due to the difference in resultant values. For this reason, uncertainty related to the roughness coefficient was analyzed in terms of change in computed variables. On average, a 20% increase of the roughness coefficient causes a 7% increase in the water depth and an 8% decrease in velocity, but there may be about a 15% increase in the water depth and an equivalent decrease in velocity for certain cross-sections in the study reach. Finally, the validity of estimated roughness coefficient based on field measurements was examined. A 10% error in discharge measurement may lead to more than 10% uncertainty in roughness coefficient estimation, but corresponding uncertainty in computed water depth and velocity is reduced to approximately 5%. Conversely, the necessity for roughness coefficient estimation by field measurement is confirmed.
Rough Electrode Creates Excess Capacitance in Thin-Film Capacitors.
Torabi, Solmaz; Cherry, Megan; Duijnstee, Elisabeth A; Le Corre, Vincent M; Qiu, Li; Hummelen, Jan C; Palasantzas, George; Koster, L Jan Anton
2017-08-16
The parallel-plate capacitor equation is widely used in contemporary material research for nanoscale applications and nanoelectronics. To apply this equation, flat and smooth electrodes are assumed for a capacitor. This essential assumption is often violated for thin-film capacitors because the formation of nanoscale roughness at the electrode interface is very probable for thin films grown via common deposition methods. In this work, we experimentally and theoretically show that the electrical capacitance of thin-film capacitors with realistic interface roughness is significantly larger than the value predicted by the parallel-plate capacitor equation. The degree of the deviation depends on the strength of the roughness, which is described by three roughness parameters for a self-affine fractal surface. By applying an extended parallel-plate capacitor equation that includes the roughness parameters of the electrode, we are able to calculate the excess capacitance of the electrode with weak roughness. Moreover, we introduce the roughness parameter limits for which the simple parallel-plate capacitor equation is sufficiently accurate for capacitors with one rough electrode. Our results imply that the interface roughness beyond the proposed limits cannot be dismissed unless the independence of the capacitance from the interface roughness is experimentally demonstrated. The practical protocols suggested in our work for the reliable use of the parallel-plate capacitor equation can be applied as general guidelines in various fields of interest.
Current Status on the Development of a Double Wall Tube Steam Generator
Energy Technology Data Exchange (ETDEWEB)
Nam, Ho Yun; Choi, Byoung Hae; Kim, Jong Man; Kim, Byung Ho
2007-12-15
A fast reactor, which uses sodium as a coolant, has a lot of merits as a next generation nuclear reactor. However, the possibility of a sodium-water reaction occurrence hinders the commercialization of this reactor. As one way to improve the reliability of a steam generator, a double-wall tube steam generator is being developed in GEN-4 program. In this report, the current state of the technical developments for a double-wall tube steam generator are reviewed and a future plan for the development of a double-wall tube steam generator is established. The current focuses of this research are an improvement of the heat transfer capability for a double-wall tube and the development of a proper leak detection method for the failure of a double-wall tube during a reactor operation. The ideal goal is an on-line leak detection of a double wall tube to prevent the sodium-water reaction. However, such a method is not developed as yet. An alternative method is being used to improve the reliability of a steam generator by performing a non-destructive test of a double wall tube during the refueling period of a reactor. In this method a straight double wall tube is employed to perform this test easily, but has a difficulty regarding an absorption of a thermal expansion of the used materials. If an on-line leak detection method is developed, the demerits of a straight double-wall tube are avoided by using a helical type double-wall tube, and the probability of a sodium-water reaction can be reduced to a level less than the design-based accident.
Roundness and straightness measurement of ceramic beam ducts for the 3 GeV-synchrotron
Energy Technology Data Exchange (ETDEWEB)
Nishizawa, Daiji; Kinsho, Michikazu; Kanazawa, Kenichiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kubo, Tomio; Sato, Yoshihiro; Saito, Yoshio [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)
2001-12-01
Large aperture ({phi}200 - {phi}250) cylindrical beam ducts consisting of alumina ceramics will be used in the 3 GeV-synchrotron of High Intensity Proton Accelerator Facility. In particular, bending magnet sections require the large length ({approx}3500 mm) ceramic beam duct connecting several unit ducts whose length is around 500-1000 mm by metallizing and glazing. Therefore it is very important to evaluate roundness and straightness of ceramic ducts because we have to compensate contact area large and have to minimize misalignment of ducts connected. We developed an apparatus for measuring roundness and straightness, and we completed data analysis method using general application software Excel as well as measuring method. Then we have taken data, and have evaluated value of roundness and straightness for the first time about 7 pieces (3 kinds) of ceramic beam duct. At last we have found out that unit ceramic ducts can be made after sintering without polishing with roundness several hundred micron ({mu}m) and straightness around 0.2-1 mm, and that straightness has a tendency to become large as duct length increases as well as roundness increases directly proportional to the maximum oblateness. (author)
Straight configuration saphenous vein transposition to popliteal artery for vascular access.
Caco, Gentian; Golemi, Dhurata; Likaj, Eriola
2017-03-21
The saphenous vein is commonly used as a vascular graft in peripheral artery surgery but rarely used for vascular access. The literature on straight configuration saphenous vein transposition to the popliteal artery is scarce. Here we present two cases of straight configuration saphenous vein transposition to the popliteal artery for vascular access, the surgical technique and respective follow-up. Two young men, aged 29 and 36 years, were chosen for lower-limb vascular access for hemodialysis. The first patient was paraplegic since birth. He used his arms to move so upper extremity vascular access was avoided. The second patient presented with an infected upper extremity arteriovenous graft (AVG) and after multiple closed AVFs he had no more available arm veins. Both patients received autologous lower extremity straight configuration saphenous vein transpositions to the popliteal artery under spinal anesthesia in May and October 2012, respectively. Cannulation of the fistula was allowed after one month. There were no early complications. Slight swelling on the leg appeared in one of the patients. Both fistulas were still functional after 36 and 32 months, respectively. The straight configuration saphenous vein transposition to popliteal artery is simple to perform, offers a long and straight segment for cannulation and may be a suitable autologous vascular access in selected patients.
Weichert, Christoph; Köchert, Paul; Schötka, Eugen; Flügge, Jens; Manske, Eberhard
2018-06-01
The uncertainty of a straightness interferometer is independent of the component used to introduce the divergence angle between the two probing beams, and is limited by three main error sources, which are linked to each other: their resolution, the influence of refractive index gradients and the topography of the straightness reflector. To identify the configuration with minimal uncertainties under laboratory conditions, a fully fibre-coupled heterodyne interferometer was successively equipped with three different wedge prisms, resulting in three different divergence angles (4°, 8° and 20°). To separate the error sources an independent reference with a smaller reproducibility is needed. Therefore, the straightness measurement capability of the Nanometer Comparator, based on a multisensor error separation method, was improved to provide measurements with a reproducibility of 0.2 nm. The comparison results revealed that the influence of the refractive index gradients of air did not increase with interspaces between the probing beams of more than 11.3 mm. Therefore, over a movement range of 220 mm, the lowest uncertainty was achieved with the largest divergence angle. The dominant uncertainty contribution arose from the mirror topography, which was additionally determined with a Fizeau interferometer. The measured topography agreed within ±1.3 nm with the systematic deviations revealed in the straightness comparison, resulting in an uncertainty contribution of 2.6 nm for the straightness interferometer.
Commissioning of the PF Ring after the Reconstruction for the Straight-sections Upgrade
International Nuclear Information System (INIS)
Honda, T.; Asaoka, S.; Cheng, W. X.; Haga, K.; Harada, K.; Hori, Y.; Izawa, M.; Kasuga, T.; Kobayashi, Y.; Maezawa, H.; Mishina, A.; Mitsuhashi, T.; Miyajima, T.; Miyauchi, H.; Nagahashi, S.; Nogami, T.; Obina, T.; Pak, C. O.; Sakanaka, S.; Sasaki, H.
2007-01-01
At the 2.5-GeV ring of the Photon Factory, a large reconstruction of the lattice around the straight sections has been accomplished in 2005. Thus reconstruction is the main part of the straight-sections upgrade project to rebuild existing undulators and to increase the number of undulator beamlines. As a result of the reconstruction, four short straight sections have been newly created and the lengths of the existing straight sections have been much extended. To exploit the new straight sections, short-period narrow-gap undulators which have a sufficiently high brilliance in hard x-ray range have been developed. The reconstruction work of the ring was completed in a seven-month shutdown from March to September, 2005. In the area over two thirds of the storage ring, all the quadrupole magnets and all the beam ducts have been renewed and rearranged to construct the new lattice. Recommissioning of the storage ring was finished at the end of October, 2005. Though we made no in-situ baking for the beam ducts, recovery of the beam lifetime has favorably progressed due to the vacuum scrubbing by the synchrotron radiation
Fong, Kahei Danny
stability equation (PSE) are performed to ensure the fidelity of the data and to study the relevant flow physics. All results unanimously confirm the conclusion that the relative location of the synchronization point with respect to the roughness element determines the roughness effect on the second mode. Namely, a roughness placed upstream of the synchronization point amplifies the unstable waves while placing a roughness downstream of the synchronization point damps the second-mode waves. The parametric study also shows that a tall roughness element within the local boundary-layer thickness results in a stronger damping effect, while the effect of the roughness width is relatively insignificant compared with the other roughness parameters. On the other hand, the fact that both LST and PSE successfully predict the damping effect only by analyzing the meanflow suggests the mechanism of the damping is by the meanflow alteration due to the existence of roughness elements, rather than new mode generation. In addition to studying the unstable waves, the drag force and heating with and without roughness have been investigated by comparing the numerical simulation data with experimental correlations. It is shown that the increase in drag force generated by the Mach wave around a roughness element in a hypersonic boundary layer is insignificant compared to the reduction of drag force by suppressing turbulent flow. The study also shows that, for a cold wall flow which is the case for practical flight applications, the Stanton number decreases as roughness elements smooth out the temperature gradient in the wall-normal direction. Based on the knowledge of roughness elements damping the second mode gained from the current study, a novel passive transition control method using judiciously placed roughness elements has been developed, and patented, during the course of this research. The main idea of the control method is that, with a given geometry and flow condition, it is possible
International Nuclear Information System (INIS)
Lu, T.; Attinger, D.; Liu, S.M.
2013-01-01
Highlights: • Temperature and velocity fluctuations in a tee junction are predicted using LES. • The numerical results are in good agreement with the experimental data. • Upstream elbow pipe has significant influence on those fluctuations. -- Abstract: Thermal striping resulting in thermal fatigue is an important safety issue for nuclear power plants. In this work, temperature and velocity fluctuations in hot and cold fluids mixing in a tee junction with the main pipe connected either to an upstream straight or elbow pipe have been numerically predicted using large-eddy simulations (LES) on the FLUENT platform with the assumption of fully-developed velocity at both main and branch pipe inlets. The numerical results for the case with an upstream straight pipe were found to be in reasonable agreement with the available experimental data. The reason for the small discrepancy between the numerical results and experimental data can be attributed to the turbulence velocity being 10% of the fully-developed velocity at the main and branch pipe inlets in the LES calculations, while in the experiments the turbulence velocity was about 10% of the average velocity upstream of the tee junction. The simulated normalized mean and root-mean square (RMS) temperatures and the velocities at both straight and elbow tees were then compared, as well as the power spectrum densities (PSD) of the temperature fluctuations. The elbow pipe upstream of the main pipe has a significant influence on the mixing, resulting in increased temperature and velocity fluctuations. The flow pattern of the elbow tee deviates from the wall jet due to the secondary flow in the upstream elbow pipe
Wall Finishes; Carpentry: 901895.
Dade County Public Schools, Miami, FL.
The course outline is designed to provide instruction in selecting, preparing, and installing wall finishing materials. Prerequisites for the course include mastery of building construction plans, foundations and walls, and basic mathematics. Intended for use in grades 11 and 12, the course contains five blocks of study totaling 135 hours of…
Wall Construction; Carpentry: 901892.
Dade County Public Schools, Miami, FL.
The curriculum guide outlines a course designed to provide instruction in floor and wall layout, and in the diverse methods and construction of walls. Upon completion of this course the students should have acquired a knowledge of construction plans and structural foundations in addition to a basic knowledge of mathematics. The course consists of…
Kruis, A.; Sneller, Lineke
2013-01-01
The subject of this teaching case is the Enterprise Resource Planning (ERP) system implementation at International Divider Walls, the world market leader in design, production, and sales of divider walls. The implementation in one of the divisions of this multinational company had been successful,
Bergshoeff, Eric A.; Kleinschmidt, Axel; Riccioni, Fabio
2012-01-01
We classify the half-supersymmetric "domain walls," i.e., branes of codimension one, in toroidally compactified IIA/IIB string theory and show to which gauged supergravity theory each of these domain walls belong. We use as input the requirement of supersymmetric Wess-Zumino terms, the properties of
Multi-scale analysis of the roughness effect on lubricated rough contact
DEMIRCI, Ibrahim
2014-01-01
Determining friction is as equally essential as determining the film thickness in the lubricated contact, and is an important research subject. Indeed, reduction of friction in the automotive industry is important for both the minimization of fuel consumption as well as the decrease in the emissions of greenhouse gases. However, the progress in friction reduction has been limited by the difficulty in understanding the mechanism of roughness effects on friction. It was observed that micro-surf...
Influence of edge roughness on graphene nanoribbon resonant tunnelling diodes
International Nuclear Information System (INIS)
Liang Gengchiau; Khalid, Sharjeel Bin; Lam, Kai-Tak
2010-01-01
The edge roughness effects of graphene nanoribbons on their application in resonant tunnelling diodes with different geometrical shapes (S, H and W) were investigated. Sixty samples for each 5%, 10% and 15% edge roughness conditions of these differently shaped graphene nanoribbon resonant tunnelling diodes were randomly generated and studied. Firstly, it was observed that edge roughness in the barrier regions decreases the effective barrier height and thickness, which increases the broadening of the quantized states in the quantum well due to the enhanced penetration of the wave-function tail from the electrodes. Secondly, edge roughness increases the effective width of the quantum well and causes the lowering of the quantized states. Furthermore, the shape effects on carrier transport are modified by edge roughness due to different interfacial scattering. Finally, with the effects mentioned above, edge roughness has a considerable impact on the device performance in terms of varying the peak-current positions and degrading the peak-to-valley current ratio.
A new fiber optic sensor for inner surface roughness measurement
Xu, Xiaomei; Liu, Shoubin; Hu, Hong
2009-11-01
In order to measure inner surface roughness of small holes nondestructively, a new fiber optic sensor is researched and developed. Firstly, a new model for surface roughness measurement is proposed, which is based on intensity-modulated fiber optic sensors and scattering modeling of rough surfaces. Secondly, a fiber optical measurement system is designed and set up. Under the help of new techniques, the fiber optic sensor can be miniaturized. Furthermore, the use of micro prism makes the light turn 90 degree, so the inner side surface roughness of small holes can be measured. Thirdly, the fiber optic sensor is gauged by standard surface roughness specimens, and a series of measurement experiments have been done. The measurement results are compared with those obtained by TR220 Surface Roughness Instrument and Form Talysurf Laser 635, and validity of the developed fiber optic sensor is verified. Finally, precision and influence factors of the fiber optic sensor are analyzed.
Numerical simulations of seepage flow in rough single rock fractures
Directory of Open Access Journals (Sweden)
Qingang Zhang
2015-09-01
Full Text Available To investigate the relationship between the structural characteristics and seepage flow behavior of rough single rock fractures, a set of single fracture physical models were produced using the Weierstrass–Mandelbrot functions to test the seepage flow performance. Six single fractures, with various surface roughnesses characterized by fractal dimensions, were built using COMSOL multiphysics software. The fluid flow behavior through the rough fractures and the influences of the rough surfaces on the fluid flow behavior was then monitored. The numerical simulation indicates that there is a linear relationship between the average flow velocity over the entire flow path and the fractal dimension of the rough surface. It is shown that there is good a agreement between the numerical results and the experimental data in terms of the properties of the fluid flowing through the rough single rock fractures.
Bardhan, Abheek; Mohan, Nagaboopathy; Chandrasekar, Hareesh; Ghosh, Priyadarshini; Sridhara Rao, D. V.; Raghavan, Srinivasan
2018-04-01
The bending and interaction of threading dislocations are essential to reduce their density for applications involving III-nitrides. Bending of dislocation lines also relaxes the compressive growth stress that is essential to prevent cracking on cooling down due to tensile thermal expansion mismatch stress while growing on Si substrates. It is shown in this work that surface roughness plays a key role in dislocation bending. Dislocations only bend and relax compressive stresses when the lines intersect a smooth surface. These films then crack. In rough films, dislocation lines which terminate at the bottom of the valleys remain straight. Compressive stresses are not relaxed and the films are relatively crack-free. The reasons for this difference are discussed in this work along with the implications on simultaneously meeting the requirements of films being smooth, crack free and having low defect density for device applications.
On designing of the thin-walled bars in the light of theory and experiments
International Nuclear Information System (INIS)
Obrebski, J.B.; Urbaniak, Z.; El-Awady, M.E.
1992-01-01
The paper presents some data and conclusions derived from the experiments and computations concerning the influence of constructional details and solutions on strength of straight thin-walled bars. The attention specially is paid to: the different instability phenomena i.e. local and global for the bar with any cross-section, the capacity of the bar by bending-torsional loading, the theory of 2d approximation, and comparisons of theoretical problems mentioned above with the proper experiments. (orig.)
Experimental Investigation of Chatter Dynamics in Thin-walled Tubular Parts Turning
GERASIMENKO, Artem; GUSKOV, Mikhail; LORONG, Philippe; DUCHEMIN, Jérôme; GOUSKOV, Alexander
2016-01-01
Chatter prediction is nowadays frequently carried out for machining operations involving deformable parts or tools. These analyses are commonly based on the uncoupled elements of the system: frequency response of the deformable parts under non-rotating conditions and cutting law. The present investigation puts forward the dynamics of a thin-walled tubular part during straight axial turning undergoing chatter instability. Studied system’s peculiarities include quasi-static nominal cutting cond...
International Nuclear Information System (INIS)
Ding Yinfeng; Zhang Zhibin; Ke Xuezhi; Zhu Zhiyuan; Zhu Dezhang; Wang Zhenxia; Xu Hongjie
2005-01-01
The single carbon atom transporting through the single-walled carbon nanotube has been studied by molecular-dynamics (MD) simulation. We got different trajectories of the carbon atom by changing the input parameters. The simulation results indicate that the single carbon atom with low energy can transport through the carbon nanotube under some input conditions and result in different trajectories being straight line or 'rosette' or circular. (authors)
The superflow state of 3He-B at a diffusive wall. Quasiclassical calculations
International Nuclear Information System (INIS)
Kopnin, N.B.; Soininen, P.I.
1992-01-01
The authors report first computations considering effects of a rough wall on the counterflow state in superfluid 3 He-B for high flow velocities. Using the quasiclassical Green's-function formalism supplemented by the boundary conditions for a diffusive wall, they calculate the order-parameter field and the supercurrent near a container wall for various pressures and temperatures. One of the results is that the current density at the wall as a function of the flow has a maximum at the velocity which is about half of the pair breaking velocity
Incorporating Skew into RMS Surface Roughness Probability Distribution
Stahl, Mark T.; Stahl, H. Philip.
2013-01-01
The standard treatment of RMS surface roughness data is the application of a Gaussian probability distribution. This handling of surface roughness ignores the skew present in the surface and overestimates the most probable RMS of the surface, the mode. Using experimental data we confirm the Gaussian distribution overestimates the mode and application of an asymmetric distribution provides a better fit. Implementing the proposed asymmetric distribution into the optical manufacturing process would reduce the polishing time required to meet surface roughness specifications.
Investigation of surface roughness influence on hyperbolic metamaterial performance
Directory of Open Access Journals (Sweden)
S. Kozik
2014-12-01
Full Text Available The main goal of this work was to introduce simple model of surface roughness which does not involve objects with complicated shapes and could help to reduce computational costs. We described and proved numerically that the influence of surface roughness at the interfaces in metal-dielectric composite materials could be described by proper selection of refractive index of dielectric layers. Our calculations show that this model works for roughness with RMS value about 1 nm and below.
Shock wave convergence in water with parabolic wall boundaries
International Nuclear Information System (INIS)
Yanuka, D.; Shafer, D.; Krasik, Ya.
2015-01-01
The convergence of shock waves in water, where the cross section of the boundaries between which the shock wave propagates is either straight or parabolic, was studied. The shock wave was generated by underwater electrical explosions of planar Cu wire arrays using a high-current generator with a peak output current of ∼45 kA and rise time of ∼80 ns. The boundaries of the walls between which the shock wave propagates were symmetric along the z axis, which is defined by the direction of the exploding wires. It was shown that with walls having a parabolic cross section, the shock waves converge faster and the pressure in the vicinity of the line of convergence, calculated by two-dimensional hydrodynamic simulations coupled with the equations of state of water and copper, is also larger
Neck Muscle Moment Arms Obtained In-Vivo from MRI: Effect of Curved and Straight Modeled Paths.
Suderman, Bethany L; Vasavada, Anita N
2017-08-01
Musculoskeletal models of the cervical spine commonly represent neck muscles with straight paths. However, straight lines do not best represent the natural curvature of muscle paths in the neck, because the paths are constrained by bone and soft tissue. The purpose of this study was to estimate moment arms of curved and straight neck muscle paths using different moment arm calculation methods: tendon excursion, geometric, and effective torque. Curved and straight muscle paths were defined for two subject-specific cervical spine models derived from in vivo magnetic resonance images (MRI). Modeling neck muscle paths with curvature provides significantly different moment arm estimates than straight paths for 10 of 15 neck muscles (p straight lines to model muscle paths can lead to overestimating neck extension moment. However, moment arm methods for curved paths should be investigated further, as different methods of calculating moment arm can provide different estimates.
First straw straightness measurements on a 4-plane end-cap ATLAS TRT wheel
Lucotte, A; Mitsou, V A; Mouraviev, S V; Nadtochy, A
2001-01-01
This document reports the first results and their interpretation of the straw straightness measurements that have been performed on the first 4-plane end-cap prototype of the ATLAS TRT. Section 2 presents the experimental setup used for the measurements, as well as a review of the data sample used to perform this study. It also provides a description of the method used to assess straw straightness, which is based on the measurements of the maximal gas gain deviation (``straw eccentricity'') seen along the straw. Section 3 reports the results of straw straightness for the 4-plane module, including corrections due to the gas flow. The effect of energy resolution degradation is also explained and results in terms of wire offset are reported. In Section 4, the straw bending due to an applied lateral deformation is measured, and finally Section 5 reviews the conclusions.
Status of PF-ring commissioning after the reconstruction for the straight-sections upgrade
International Nuclear Information System (INIS)
Tanimoto, Yasunori; Miyauchi, Hiroshi; Honda, Tohru; Kobayashi, Yukinori
2006-01-01
The upgrade project of the straight sections at the PF-ring enables the reinforcement of insertion devices and their beamlines. As a main part of this project, a large-scale reconstruction of the storage ring was carried out from March to September in 2005. The lattice configuration was modified to create short straight sections of 1.4 m and to extend the existing straight sections. Optical functions of the short sections were optimized for short-gap mini-pole undulators as X-ray sources. The first mini-pole undulator SGU no.17 has been operated for a protein crystallography. A recommissioning of the ring was conducted for about one month, and user experiments were restarted on 18th October 2005 according to schedule. The recovery of the beam lifetime due to the process of the vacuum scrubbing has been favorably progressed. (author)
Calculation of gas Bremsstrahlung power from straight sections of storage ring at SSRF
International Nuclear Information System (INIS)
Hua Zhengdong; Xu Xunjiang; Fang Keming; Xu Jiaqiang
2008-01-01
The Shanghai Synchrotron Radiation Facility (SSRF) is a third-generation synchrotron radiation light source with 3.5 GeV in energy, which is composed of the linear accelerator, the booster and the storage ring. The storage ring provides 16 standard straight sections of 6.5 m and 4 long straight sections of 12 meters. Gas Bremsstrahlung (GB) produced by the interaction of the stored beam with the residual gas molecules in straight section, which is so intense and has a very small angular that the GB spectra, the GB power and the GB power distribution should be known. The characters of GB are studied by means of Fluka Monte Carlo code. Our result shows agreement with those obtained by the experiential formulae. (authors)
Synthesis method based on solution regions for planar four bar straight line linkages
International Nuclear Information System (INIS)
Lai Rong, Yin; Cong, Mao; Jian you, Han; Tong, Yang; Juan, Huang
2012-01-01
An analytical method for synthesizing and selecting desired four-bar straight line mechanisms based on solution regions is presented. Given two fixed pivots, the point position and direction of the target straight line, an infinite number of mechanism solutions can be produced by employing this method, both in the general case and all three special cases. Unifying the straight line direction and the displacement from the given point to the instant center into the same form with different angles as parameters, infinite mechanism solutions can be expressed with different solution region charts. The mechanism property graphs have been computed to enable the designers to find out the involved mechanism information more intuitively and avoid aimlessness in selecting optimal mechanisms
Seki, Hirokazu; Tadakuma, Susumu
This paper describes a novel straight and circular road driving control scheme for electric power assisted wheelchairs. “Electric power assisted wheelchair” which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people, however, the performance of the straight and circular road driving must be further improved because the two wheels drive independently. This paper proposes a novel driving control scheme based on fuzzy algorithm to realize the stable and reliable driving on straight and circular roads. The suitable assisted torque of the right and left wheels is determined by fuzzy algorithm based on the posture angular velocity of the wheelchair and the human input torque proportion of the right and left wheels. Some experiments on the practical roads show the effectiveness of the proposed control system.
Energy Technology Data Exchange (ETDEWEB)
Li, Xun [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructure, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Xu, Zheng, E-mail: zhengxu@nju.edu.cn [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructure, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)
2012-12-15
Graphical abstract: The helical, straight and hollow carbon nanofibers can be selectively synthesized by adjusting either the reaction temperature or feed gas composition. Display Omitted Highlights: ► CNFs were synthesized via pyrolysis of acetylene on copper NPs. ► The helical, straight, hollow and N-doped CNFs can be selectively synthesized. ► The growth mechanism of different types of CNFs was proposed. -- Abstract: Carbon nanofibers (CNFs) with various morphologies were synthesized by catalytic pyrolysis of acetylene on copper nanoparticles which were generated from the in situ decomposition of copper acetylacetonate. The morphology of the pristine and acid-washed CNFs was investigated by field emission scanning electron microscope and high-resolution transmission electron microscope. Helical, straight and hollow CNFs can be selectively synthesized by adjusting either the reaction temperature or feed gas composition. The growth mechanism for these three types of CNFs was proposed.
"Appearance potent"? A content analysis of UK gay and straight men's magazines.
Jankowski, Glen S; Fawkner, Helen; Slater, Amy; Tiggemann, Marika
2014-09-01
With little actual appraisal, a more 'appearance potent' (i.e., a reverence for appearance ideals) subculture has been used to explain gay men's greater body dissatisfaction in comparison to straight men's. This study sought to assess the respective appearance potency of each subculture by a content analysis of 32 issues of the most read gay (Attitude, Gay Times) and straight men's magazines (Men's Health, FHM) in the UK. Images of men and women were coded for their physical characteristics, objectification and nudity, as were the number of appearance adverts and articles. The gay men's magazines featured more images of men that were appearance ideal, nude and sexualized than the straight men's magazines. The converse was true for the images of women and appearance adverts. Although more research is needed to understand the effect of this content on the viewer, the findings are consistent with a more appearance potent gay male subculture. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.
Constraining the roughness degree of slip heterogeneity
Causse, Mathieu
2010-05-07
This article investigates different approaches for assessing the degree of roughness of the slip distribution of future earthquakes. First, we analyze a database of slip images extracted from a suite of 152 finite-source rupture models from 80 events (Mw = 4.1–8.9). This results in an empirical model defining the distribution of the slip spectrum corner wave numbers (kc) as a function of moment magnitude. To reduce the “epistemic” uncertainty, we select a single slip model per event and screen out poorly resolved models. The number of remaining models (30) is thus rather small. In addition, the robustness of the empirical model rests on a reliable estimation of kc by kinematic inversion methods. We address this issue by performing tests on synthetic data with a frequency domain inversion method. These tests reveal that due to smoothing constraints used to stabilize the inversion process, kc tends to be underestimated. We then develop an alternative approach: (1) we establish a proportionality relationship between kc and the peak ground acceleration (PGA), using a k−2 kinematic source model, and (2) we analyze the PGA distribution, which is believed to be better constrained than slip images. These two methods reveal that kc follows a lognormal distribution, with similar standard deviations for both methods.
Spectrophotometric Examination of Rough Print Surfaces
Directory of Open Access Journals (Sweden)
Erzsébet Novotny
2011-05-01
Full Text Available The objective was to assess the impact of the surface texture of individual creative paper types (coated or patternedon the quality of printing and to identify to what extent the various creative paper types require specific types ofspectrophotometers. We used stereomicroscopic images to illustrate unprinted and printed surfaces of creative papertypes. Surface roughness was measured to obtain data on the unevenness of surfaces. Spectrophotometric tests wereused to select the most suitable spectrophotometer from meters with different illumination setup for testing anygiven print. For the purpose of testing, we used spectrophotometers which are commonly available generally used totest print products for colour accuracy. With the improvement of measuring geometries, illumination setup, colourmeasurement becomes more and more capable of producing reliable results unaffected by surface textures. Our testshave proved this fact by showing that the GretagMacbeth Spectrolino with annular illumination is less sensitive tosurface texture than the X-Rite Spetrodensitometer and the Techkon SpetroDens with directional illumination. Furthertests have brought us to the conclusion that there is a difference even between the two devices with directionalillumination. While the X-Rite 530 Spectrodensitometer is more suitable for testing coated surfaces, the TechkonSpectroDens can come close to ΔE*ab values produced by the annular illuminated device for textured surfaces.
Radiosensitivity of the rough-skinned newt
International Nuclear Information System (INIS)
Willis, D.L.; Lappenbusch, W.L.
1974-01-01
Newts were collected locally and maintained unfed at 10 0 C both before and after irradiation. Whole-body exposures ranging up to 80 kR were given with 250 kVp x rays, 300 kVp x rays, and 60 Co gamma rays. The mean survival time-exposure curve was sigmoid, following the typical appearance of such curves for mammalian species. A dose-independent region extending from roughly 700 to 5,000 R was evident. A variety of skin lesions and depigmentation effects were noted at exposures above 250 R, whose time of appearance decreased with increasing dose. A total of 832 newts were used in this phase of the study. Assuming that hematopoietic damage was primarily responsible for deaths below 700-800 R, additional studies of hematopoiesis were initiated. The effect of a 650 R-exposure on liver weight, spleen weight and concentration of circulating red blood cells for 1 1 / 2 months post-irradiation was assessed. The results indicate a progressive state of anemia. This was further substantiated by a study of 59 Fe incorporation by red blood cells at intervals up to one month for five exposures ranging up to 1000 R. (U.S.)
Estimation of fracture roughness from the acoustic borehole televiewer image
International Nuclear Information System (INIS)
Bae, Dae Soek; Kim, Chun Soo; Kim, Kyung Soo; Park, Byung Yoon; Koh, Yong Kweon
2000-12-01
Estimation of fracture roughness - as one of the basic hydraulic fracture parameters - is very important in assessing ground water flow described by using discrete fracture network modeling. Former manual estimation of the roughness for each fracture surface of drill cores is above all a tedious, time-consuming work and will often cause some ambiguities of roughness interpretation partly due to the subjective judgements of observers, and partly due to the measuring procedure itself. However, recently, indebt to the highly reliable Televiewer data for the fracture discrimination, it has led to a guess to develop a relationship between the traditional roughness method based on a linear profiles and the method from the Televiewer image based on a ellipsoidal profile. Hence, the aim of this work is to develop an automatic evaluation algorithm for measuring the roughness from the Televiewer images. A highly reliable software named 'FRAFA' has been developed and realized to the extent that its utility merits. In the developing procedure, various problems - such as the examination of a new base line(ellipsoidal) for measuring the unevenness of fracture, the elimination of overlapping fracture signatures or noise, the wavelet estimation according to the type of fractures and the digitalization of roughness etc. - were considered. With these consideration in mind, the newly devised algorithm for the estimation of roughness curves showed a great potential not only for avoiding ambiguities of roughness interpretation but also for the judgement of roughness classification
Digital Repository Service at National Institute of Oceanography (India)
Chakraborty, B.; Schenke, H.W.; Kodagali, V.N.; Hagen, R.
composite roughness model, including water-sediment interface roughness and sediment volume roughness parameters the data was modeled. The model effectively uses the near normal incidence angle backscatter to determine the seafloor interface roughness...
International Nuclear Information System (INIS)
Won, Jong Boo; Park, Sung Ho; Hong, Jong Won; Kim, Yoo Kyoung; Shin, Mi Jeong; Baik, Seung Kuk; Choi, Han Yong; Kim, Bong Gi
1999-01-01
To analyze the radiologic-especially angiographic-findings of deep seated cerebral arteriovenous malformation(AVM) involving nonvisualized straight sinus. In six patients aged between 15 and 53 years with deep seated cerebral AVM, CT and MR images were retrospectively analyzed with regard to the following features : the presence of straight sinus, the location of AVM, and the occurrence of hemorrhage. Angiograms were analyzed for venous drainage routes of AVM, the appearance of veins, the presence of falcine sinus and venous drainage from normal deep brain parenchyme. In four patients who had undergone intravascular embolization therapy, pre- and post- embolization angiograms were compared. CT and MR images showed neither straight sinus nor thrombosis. AVMs were deeply seated in the brain, and in all cases there was cerebral hemorrhage. Angiograms disclosed that venous drainage of all AVMs occurred via the veins of Galen. In one case, venous flow via the falcine sinus to the superior sagittal sinus was noted, but in others, retrograde flow in the deep venous system was observed. Marked collateral routes followed in response to the obstruction of straight sinus included the basal vein of Rosenthal, the internal occipital, internal cerebral, and cerebellar hemispheric veins (which are Galenic afferents), and the inferior sagittal sinus. In all patients, contralateral routes were partially involved. Venous drainage from normal deep parenchyme through the transcerebral veins to the superficial venous system was noted, and in one case, straight sinus which had been observed on an angiogram five years earlier was no longer present. Angiography offers effective evaluation of the dynamic aspect of venous flow in cases involving deep-seated AVM, and of normal deep parenchyme in cases in which AVM involves nonvisualized straight sinus. Before intravascular treatment of AVM, venous flow must be carefully analyzed
Edie, P. C.
1981-01-01
Straight and chopped DC motor performances for a Reliance EV-250AT motor with an EV-1 controller were examined. Effects of motor temperature and operating voltage are shown. It is found that the maximum motor efficiency is approximately 85% at low operating temperatures in the straight DC mode. Chopper efficiency is 95% under all operating conditions. For equal speeds, the motor operated in the chopped mode develops slightly more torque and draws more current than it does in the straight DC mode.
International Nuclear Information System (INIS)
Paudel, Eak Raj
2007-01-01
Gravitational field of Schwarzschild and Schwarzschild de-sitter Black hole with a straight string passing through it. In such space analytical and numerical solutions of null and time like geodesics are investigated. The string parameter a + is found to affect both the angle of deflection in null geodesics and the precession of perihelion on time like geodesics .It is seen that the deflection of null and time like geodesics near the gravitating mass of de-sitter space time increases with t he gravitational field of a straight string in flat space time has the property that the Newtonian potential vanishes yet there are non trivial gravitational effects. A test particle is neither attracted nor repelled by a string, yet the conical nature of space outside of string produces observable effects such as light deflection . Schwarzschild Black hole is a mathematical solution to the Einstein's field equations and corresponds to the gravitational field of massive compact spherically symmetric ob normal. References 1. Aryal, M.M, A. Vilenkin and L.H Ford, 1986, Phys.Rev. D32 ,2262 2. Moriyasu ,K ., 1980 , An introduction to gauge Invariance 3. Vilenkin A., 1985 , Physical reports , cosmic strings and Domain walls 4. Berry, M. , 1976 , Principle of cosmology and Gravitation 5. Mishner , C.W ., K.S .Throne , J.A wheeler , 1973. (Author)
DEFF Research Database (Denmark)
Wittchen, Kim Bjarne
tsbi3 is a user-friendly and flexible computer program, which provides support to the design team in the analysis of the indoor climate and the energy performance of buildings. The solar wall module gives tsbi3 the capability of simulating solar walls and their interaction with the building....... This version, C, of tsbi3 is capable of simulating five types of solar walls say: mass-walls, Trombe-walls, double Trombe-walls, internally ventilated walls and solar walls for preheating ventilation air. The user's guide gives a description of the capabilities and how to simulate solar walls in tsbi3....
Cubic systems with invariant affine straight lines of total parallel multiplicity seven
Directory of Open Access Journals (Sweden)
Alexandru Suba
2013-12-01
Full Text Available In this article, we study the planar cubic differential systems with invariant affine straight lines of total parallel multiplicity seven. We classify these system according to their geometric properties encoded in the configurations of invariant straight lines. We show that there are only 17 different topological phase portraits in the Poincar\\'e disc associated to this family of cubic systems up to a reversal of the sense of their orbits, and we provide representatives of every class modulo an affine change of variables and rescaling of the time variable.
A potential flow 2-D vortex panel model: Applications to vertical axis straight blade tidal turbine
International Nuclear Information System (INIS)
Wang, L.B.; Zhang, L.; Zeng, N.D.
2007-01-01
A potential flow 2-D vortex panel model (VPM2D) for unsteady hydrodynamics calculation of the vertical axis straight blade variable pitch turbine was given for tidal streams energy conversion. Numerical results of predicted instantaneous blade forces and wake flow of the rotor showed good agreement with the test data. The model was also compared with the previous classic free vortex model (V-DART) and vortex method combined with finite element analysis (FEVDTM). It showed that the present model was much better than the former, less complex than the latter and suitable for designing and optimization of the vertical axis straight blade turbine
Synthesis and characterization of straight and stacked-sheet AlN nanowires with high purity
International Nuclear Information System (INIS)
Lei, M.; Yang, H.; Li, P.G.; Tang, W.H.
2008-01-01
Large-scale AlN nanowires with hexagonal crystal structure were synthesized by the direct nitridation method at high temperatures. The experimental results indicate that these single-crystalline AlN nanowires have high purity and consist of straight and stacked-sheet nanowires. It is found that straight AlN nanowire grows along [1, 1, -2, 0] direction, whereas the stacked-sheet nanowire with hexagonal cross section is along [0 0 0 1] direction. It is thought that vapor-solid (VS) mechanism should be responsible for the growth of AlN nanowires
The appearance potency of gay and straight men’s websites
Jankowski, G.; Slater, A.; Tiggemann, M.; Fawkner, H.
2016-01-01
Gay men's greater body dissatisfaction compared to straight men has been explained as a result of gay men’s more 'appearance potent' subculture. This study aimed to critically appraise this explanation by assessing images of men and women for their physical characteristics and objectification across 8 popular gay and straight men's dating and porn websites. 1,415 images of men and 715 images of women across the website’s main pages were coded. Results showed that the gay men's websites featur...
The Planning of Straight Line Trajectory in Robotics Using Interactive Graphics
Directory of Open Access Journals (Sweden)
Kesheng Wang
1987-07-01
Full Text Available The planning of straight line trajectory using the interactive computer graphics simulation of robot manipulator movement is discussed. This new approach to straight line motion planning improves the 'bound deviation joint paths' developed by R. M. Taylor (1979. The new approach has three characteristics: (1 linear interpolation in joint space; (2 unequal intervals for interpolating knot points; (3 using interactive computer graphics to assure that the maximum deviation in the whole segment is less than the pre-specified values. The structure and mathematical basis of a computer program developed for this purpose are presented.
Gender, Health Behavior, and Intimate Relationships: Lesbian, Gay, and Straight Contexts
Reczek, Corinne; Umberson, Debra
2011-01-01
Many studies focus on health behavior within the context of intimate ties. However, this literature is limited by reliance on gender socialization theory and a focus on straight (i.e., heterosexual) marriage. We extend this work with an analysis of relationship dynamics around health behavior in 20 long-term straight marriages as well as 15 gay and 15 lesbian long-term cohabiting partnerships in the United States (N=100 individual in-depth interviews). We develop the concept of “health behavi...
Shielded transient self-interaction of a bunch entering a circle from a straight path
International Nuclear Information System (INIS)
Li, R.; Bohn, C.L.; Bisognano, J.J.
1997-01-01
When a short (mm-length) bunch with high (nC-regime) charge is transported through a magnetic bending system, self-interaction via coherent synchrotron radiation (CSR) and space charge may alter the bunch dynamics significantly. The authors consider a Gaussian rigid-line-charge bunch following a straight-path trajectory into a circle, with the trajectory centered between two infinite, parallel, perfectly conducting plates. Transients associated with CSR and space charge generated from source particles both on the straight path and the circle are calculated, and their net effect on the radiated power is contrasted with that of shielded steady-state CSR
International Nuclear Information System (INIS)
Majid, A.
1998-01-01
Heat transfer to liquid sodium in the presence of a transverse magnetic field and gravity field was analyzed in a square cross section straight duct. The duct had conducting vanadium walls. Magnetohydrodynamic equations in three dimensions and energy equation in three dimensions in cartesian coordinate system were solved. Firstly Nusselt number was calculated with no magnetic field and gravity field. Secondly the Nusselt number was calculated for the case of transverse magnetic field acting on the fluid. Thirdly Nusselt number was calculated for the case of transverse magnetic field and gravity field acting on the fluid. Only one face of the channel was heated. It was found that Nusselt number is not sensitive to application of gravity field and is slightly sensitive to application of transverse magnetic field. The sensitivity of Nusselt number to magnetic field intensity becomes almost negligible after increasing the strength of magnetic field to 0.1 Tesla. (author)
International Nuclear Information System (INIS)
Behrisch, Rainer
1978-01-01
The plasma wall interactions for two extreme cases, the 'vacuum model' and the 'cold gas blanket' are outlined. As a first step for understanding the plasma wall interactions the elementary interaction processes at the first wall are identified. These are energetic ion and neutral particle trapping and release, ion and neutral backscattering, ion sputtering, desorption by ions, photons and electrons and evaporation. These processes have only recently been started to be investigated in the parameter range of interest for fusion research. The few measured data and their extrapolation into regions not yet investigated are reviewed
Physically-consistent wall boundary conditions for the k-ω turbulence model
DEFF Research Database (Denmark)
Fuhrman, David R.; Dixen, Martin; Jacobsen, Niels Gjøl
2010-01-01
A model solving Reynolds-averaged Navier–Stokes equations, coupled with k-v turbulence closure, is used to simulate steady channel flow on both hydraulically smooth and rough beds. Novel experimental data are used as model validation, with k measured directly from all three components of the fluc......A model solving Reynolds-averaged Navier–Stokes equations, coupled with k-v turbulence closure, is used to simulate steady channel flow on both hydraulically smooth and rough beds. Novel experimental data are used as model validation, with k measured directly from all three components...... of the fluctuating velocity signal. Both conventional k = 0 and dk/dy = 0 wall boundary conditions are considered. Results indicate that either condition can provide accurate solutions, for the bulk of the flow, over both smooth and rough beds. It is argued that the zero-gradient condition is more consistent...... with the near wall physics, however, as it allows direct integration through a viscous sublayer near smooth walls, while avoiding a viscous sublayer near rough walls. This is in contrast to the conventional k = 0 wall boundary condition, which forces resolution of a viscous sublayer in all circumstances...
Fuzzy multi-project rough-cut capacity planning
Masmoudi, Malek; Hans, Elias W.; Leus, Roel; Hait, Alain; Sotskov, Yuri N.; Werner, Frank
2014-01-01
This chapter studies the incorporation of uncertainty into multi-project rough-cut capacity planning. We use fuzzy sets to model uncertainties, adhering to the so-called possibilistic approach. We refer to the resulting proactive planning environment as Fuzzy Rough Cut Capacity Planning (FRCCP).
Sub-Patch Roughness in Earthquake Rupture Investigations
Zielke, Olaf
2016-02-13
Fault geometric complexities exhibit fractal characteristics over a wide range of spatial scales (<µm to >km) and strongly affect the rupture process at corresponding scales. Numerical rupture simulations provide a framework to quantitatively investigate the relationship between a fault\\'s roughness and its seismic characteristics. Fault discretization however introduces an artificial lower limit to roughness. Individual fault patches are planar and sub-patch roughness –roughness at spatial scales below fault-patch size– is not incorporated. Does negligence of sub-patch roughness measurably affect the outcome of earthquake rupture simulations? We approach this question with a numerical parameter space investigation and demonstrate that sub-patch roughness significantly modifies the slip-strain relationship –a fundamental aspect of dislocation theory. Faults with sub-patch roughness induce less strain than their planar-fault equivalents at distances beyond the length of a slipping fault. We further provide regression functions that characterize the stochastic effect sub-patch roughness.
Heat transfer and pressure drop in microchannels with random roughness
Pelevic, N.; van der Meer, Theodorus H.
2016-01-01
The effect of surface roughness on heat transfer and fluid flow phenomena within a microchannel has been investigated by using the lattice Boltzmann method. The surface roughness has been generated by using Gaussian function. Gaussian function is an efficient and convenient method to create surface
Assessing of channel roughness and temperature variations on ...
African Journals Online (AJOL)
Assessing of channel roughness and temperature variations on wastewater quality parameters using numerical modeling. ... According to the obtained results, nitrate (NO3) has a decreasing trend when the Manning Roughness Coefficient (N) is higher than 0.04 along the channel, but is reduced when “N” is less than 0.04.
Gliding Swifts Attain Laminar Flow over Rough Wings
Lentink, D.; Kat, de R.
2014-01-01
Swifts are among the most aerodynamically refined gliding birds. However, the overlapping vanes and protruding shafts of their primary feathers make swift wings remarkably rough for their size. Wing roughness height is 1–2% of chord length on the upper surface—10,000 times rougher than sailplane
A Meta-Analysis: Acoustic Measurement of Roughness and Breathiness
v. Latoszek, Ben Barsties; Maryn, Youri; Gerrits, Ellen; De Bodt, Marc
2018-01-01
Purpose: Over the last 5 decades, many acoustic measures have been created to measure roughness and breathiness. The aim of this study is to present a meta-analysis of correlation coefficients (r) between auditory-perceptual judgment of roughness and breathiness and various acoustic measures in both sustained vowels and continuous speech. Method:…
Road roughness evaluation using in-pavement strain sensors
Zhang, Zhiming; Deng, Fodan; Huang, Ying; Bridgelall, Raj
2015-11-01
The international roughness index (IRI) is a characterization of road roughness or ride quality that transportation agencies most often report. The prevalent method of acquiring IRI data requires instrumented vehicles and technicians with specialized training to interpret the results. The extensive labor and high cost requirements associated with the existing approaches limit data collection to at most once per year for portions of the national highway system. Agencies characterize roughness only for some secondary roads but much less frequently, such as once every five years, resulting in outdated roughness information. This research developed a real-time roughness evaluation approach that links the output of durable in-pavement strain sensors to prevailing indices that summarize road roughness. Field experiments validated the high consistency of the approach by showing that it is within 3.3% of relative IRI estimates. After their installation and calibration during road construction, the ruggedized strain sensors will report road roughness continuously. Thus, the solution will provide agencies a real-time roughness monitoring solution over the remaining service life of road assets.
Model of rough bed for numerical simulation of saltation
Czech Academy of Sciences Publication Activity Database
Kharlamova, Irina; Vlasák, Pavel
2015-01-01
Roč. 19, č. 3 (2015), s. 366-385 ISSN 1964-8189 R&D Projects: GA ČR GA103/09/1718; GA ČR GAP105/10/1574 Institutional support: RVO:67985874 Keywords : saltation * bed load transport * rough bed * armoured bed * bed roughness Subject RIV: BK - Fluid Dynamics Impact factor: 0.636, year: 2015
PhysarumSoft: An update based on rough set theory
Schumann, Andrew; Pancerz, Krzysztof
2017-07-01
PhysarumSoft is a software tool consisting of two modules developed for programming Physarum machines and simulating Physarum games, respectively. The paper briefly discusses what has been added since the last version released in 2015. New elements in both modules are based on rough set theory. Rough sets are used to model behaviour of Physarum machines and to describe strategy games.
Roughness effect on the efficiency of dimer antenna based biosensor
Directory of Open Access Journals (Sweden)
D. Barchiesi
2012-09-01
Full Text Available The fabrication process of nanodevices is continually improved. However, most of the nanodevices, such as biosensors present rough surfaces with mean roughness of some nanometers even if the deposition rate of material is more controlled. The effect of roughness on performance of biosensors was fully addressed for plane biosensors and gratings, but rarely addressed for biosensors based on Local Plasmon Resonance. The purpose of this paper is to evaluate numerically the influence of nanometric roughness on the efficiency of a dimer nano-biosensor (two levels of roughness are considered. Therefore, we propose a general numerical method, that can be applied to any other nanometric shape, to take into account the roughness in a three dimensional model. The study focuses on both the far-field, which corresponds to the experimental detected data, and the near-field, responsible for exciting and then detecting biological molecules. The results suggest that the biosensor efficiency is highly sensitive to the surface roughness. The roughness can produce important shifts of the extinction efficiency peak and a decrease of its amplitude resulting from changes in the distribution of near-field and absorbed electric field intensities.
Roughness of grain boundaries in partly recrystallized aluminum
DEFF Research Database (Denmark)
Sun, Jun; Zhang, Yubin; Juul Jensen, Dorte
2017-01-01
cold rolled aluminum samples. The results show that particle pinning is not the main reason accounting for recrystallization boundary roughness in the present samples. The roughness is however shown to relate to the deformation microstructure and possible effects of migration rate are discussed...
Rough Mill Improvement Guide for Managers and Supervisors
Philip H. Mitchell; Jan Wiedenbeck; Bobby Ammerman; Bobby Ammerman
2005-01-01
Wood products manufacturers require an efficient recovery of product from lumber to remain profitable. A company's ability to obtain the best yield in lumber cut-up operations (i.e., the rough mill) varies according to the raw material, product, processing equipment, processing environment, and knowledge and skill of the rough mill's employees. This book...
The Terahertz Scattering Analysis of Rough Metallic and Dielectric Targets
Directory of Open Access Journals (Sweden)
Mou Yuan
2018-02-01
Full Text Available The terahertz scattering characteristics of metallic and dielectric rough targets is important for the investigation of the terahertz radar targets properties. According to the stationary phase theory and scalar approximation, if the radius of curvature at any point of the surface is much larger than the incident wavelength, and the wavelength is also much longer than the surface height function and Root-Mean-Square (RMS surface slope, the coherent and incoherent scattering Radar Cross Section (RCS of rough metallic and dielectric targets can be obtained. Based on the stationary phase approximation, the coherent RCS of rough conductors, smooth dielectric targets and rough dielectric targets can be easily deputed. The scattering characteristics of electrically large smooth Al and painted spheres are investigated in this paper, and the calculated RCS are verified by Mie scattering theory, the error is less than 0.1 dBm2. Based on lambert theory, it is demonstrated that the incoherent RCS is analyzed with better precision if the rough surfaces are divided into much more facets. In this paper, the coherent and incoherent scattering of rough Al and painted spheres are numerically observed, and the effects of surface roughness and materials are analyzed. The conclusions provide theoretical foundation for the terahertz scattering characteristics of electrically large rough targets.
CSIR Research Space (South Africa)
De Villiers, A
2010-01-01
Full Text Available The question addressed by this chapter is: How should advanced walling systems be planned, designed, built, refurbished, and end their useful lives, to classify as smart, sustainable, green or eco-building environments?...
International Nuclear Information System (INIS)
Behrisch, R.
1976-01-01
Some of the relevant elementary atomic processes which are expected to be of significance to the first wall of a fusion reactor are reviewed. Up to the present, most investigations have been performed at relatively high ion energies, typically E greater than 5 keV, and even in this range the available data are very poor. If the plasma wall interaction takes place at energies of E greater than 1 keV the impurity introduction and first wall erosion which will take place predominantly by sputtering, will be large and may severely limit the burning time of the plasma. The wall bombardment and surface erosion will presumably not decrease substantially by introducing a divertor. The erosion can only be kept low if the energy of the bombarding ions and neutrals can be kept below the threshold for sputtering of 1 to 10 eV. 93 refs
Comparison of optical methods for surface roughness characterization
DEFF Research Database (Denmark)
Feidenhans'l, Nikolaj Agentoft; Hansen, Poul Erik; Pilny, Lukas
2015-01-01
We report a study of the correlation between three optical methods for characterizing surface roughness: a laboratory scatterometer measuring the bi-directional reflection distribution function (BRDF instrument), a simple commercial scatterometer (rBRDF instrument), and a confocal optical profiler....... For each instrument, the effective range of spatial surface wavelengths is determined, and the common bandwidth used when comparing the evaluated roughness parameters. The compared roughness parameters are: the root-mean-square (RMS) profile deviation (Rq), the RMS profile slope (Rdq), and the variance...... of the scattering angle distribution (Aq). The twenty-two investigated samples were manufactured with several methods in order to obtain a suitable diversity of roughness patterns.Our study shows a one-to-one correlation of both the Rq and the Rdq roughness values when obtained with the BRDF and the confocal...
Computer simulation of RBS spectra from samples with surface roughness
Energy Technology Data Exchange (ETDEWEB)
Malinský, P., E-mail: malinsky@ujf.cas.cz [Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, v. v. i., 250 68 Rez (Czech Republic); Department of Physics, Faculty of Science, J. E. Purkinje University, Ceske mladeze 8, 400 96 Usti nad Labem (Czech Republic); Hnatowicz, V., E-mail: hnatowicz@ujf.cas.cz [Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, v. v. i., 250 68 Rez (Czech Republic); Macková, A., E-mail: mackova@ujf.cas.cz [Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, v. v. i., 250 68 Rez (Czech Republic); Department of Physics, Faculty of Science, J. E. Purkinje University, Ceske mladeze 8, 400 96 Usti nad Labem (Czech Republic)
2016-03-15
A fast code for the simulation of common RBS spectra including surface roughness effects has been written and tested on virtual samples comprising either a rough layer deposited on a smooth substrate or smooth layer deposited on a rough substrate and simulated at different geometries. The sample surface or interface relief has been described by a polyline and the simulated RBS spectrum has been obtained as the sum of many particular spectra from randomly chosen particle trajectories. The code includes several procedures generating virtual samples with random and regular (periodical) roughness. The shape of the RBS spectra has been found to change strongly with increasing sample roughness and an increasing angle of the incoming ion beam.
International Nuclear Information System (INIS)
Reichle, R.
2004-01-01
This document gathers the 43 slides presented in the framework of the week long lecture 'hot plasmas 2004' and dedicated to plasma-wall interaction in a tokamak. This document is divided into 4 parts: 1) thermal load on the wall, power extraction and particle recovery, 2) basic edge plasma physics, 3) processes that drive the plasma-solid interaction, and 4) material conditioning (surface treatment...) for ITER