WorldWideScience

Sample records for alternately rotating walls

  1. Rotational Response of Toe-Restrained Retaining Walls to Earthquake Ground Motions

    National Research Council Canada - National Science Library

    Ebeling, Robert M; White, Barry C

    2006-01-01

    .... The PC software CorpsWallRotate (sometimes referred to as CWRotate) was developed to perform an analysis of permanent wall rotation for each proposed retaining wall section to a user-specified earthquake acceleration time-history...

  2. LES of turbulent flow in a concentric annulus with rotating outer wall

    International Nuclear Information System (INIS)

    Hadžiabdić, M.; Hanjalić, K.; Mullyadzhanov, R.

    2013-01-01

    Highlights: • High rotation up to N = 2 dampens progressively the turbulence near the rotating outer wall. • At 2 2.8, while tending to laminarize, the flow exhibits distinct Taylor-Couette vortical rolls. -- Abstract: Fully-developed turbulent flow in a concentric annulus, r 1 /r 2 = 0.5, Re h = 12,500, with the outer wall rotating at a range of rotation rates N = U θ,wall /U b from 0.5 up to 4 is studied by large-eddy simulations. The focus is on the effects of moderate to very high rotation rates on the mean flow, turbulence statistics and eddy structure. For N up to ∼2, an increase in the rotation rate dampens progressively the turbulence near the rotating outer wall, while affecting only mildly the inner-wall region. At higher rotation rates this trend is reversed: for N = 2.8 close to the inner wall turbulence is dramatically reduced while the outer wall region remains turbulent with discernible helical vortices as the dominant turbulent structure. The turbulence parameters and eddy structures differ significantly for N = 2 and 2.8. This switch is attributed to the centrifuged turbulence (generated near the inner wall) prevailing over the axial inertial force as well as over the counteracting laminarizing effects of the rotating outer wall. At still higher rotation, N = 4, the flow gets laminarized but with distinct spiralling vortices akin to the Taylor–Couette rolls found between the two counter-rotating cylinders without axial flow, which is the limiting case when N approaches to infinity. The ratio of the centrifugal to axial inertial forces, Ta/Re 2 ∝ N 2 (where Ta is the Taylor number) is considered as a possible criterion for defining the conditions for the above regime change

  3. Particle Trajectories in Rotating Wall Cell Culture Devices

    Science.gov (United States)

    Ramachandran N.; Downey, J. P.

    1999-01-01

    Cell cultures are extremely important to the medical community since such cultures provide an opportunity to perform research on human tissue without the concerns inherent in experiments on individual humans. Development of cells in cultures has been found to be greatly influenced by the conditions of the culture. Much work has focused on the effect of the motions of cells in the culture relative to the solution. Recently rotating wall vessels have been used with success in achieving improved cellular cultures. Speculation and limited research have focused on the low shear environment and the ability of rotating vessels to keep cells suspended in solution rather than floating or sedimenting as the primary reasons for the improved cellular cultures using these devices. It is widely believed that the cultures obtained using a rotating wall vessel simulates to some degree the effect of microgravity on cultures. It has also been speculated that the microgravity environment may provide the ideal acceleration environment for culturing of cellular tissues due to the nearly negligible levels of sedimentation and shear possible. This work predicts particle trajectories of cells in rotating wall vessels of cylindrical and annular design consistent with the estimated properties of typical cellular cultures. Estimates of the shear encountered by cells in solution and the interactions with walls are studied. Comparisons of potential experiments in ground and microgravity environments are performed.

  4. Near-Wall Turbulence Modelling of Rotating and Curved Shear Flows

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, Bjoern Anders

    1997-12-31

    This thesis deals with verification and refinement of turbulence models within the framework of the Reynolds-averaged approach. It pays special attention to modelling the near-wall region, where the turbulence is strongly non-homogeneous and anisotropic. It also studies in detail the effects associated with an imposed rotation of the reference frame or streamline curvature. The objective with near-wall turbulence closure modelling is to formulate a set of equations governing single point turbulence statistics, which can be solved in the region of the flow which extends to the wall. This is in contrast to the commonly adopted wall-function approach in which the wall-boundary conditions are replaced by matching conditions in the logarithmic region. The near-wall models allow more flexibility by not requiring any such universal behaviour. Assessment of the novel elliptic relaxation approach to model the proximity of a solid boundary reveals an encouraging potential used in conjunction with second-moment and eddy-viscosity closures. The most natural level of closure modelling to predict flows affected by streamline curvatures or an imposed rotation of the reference frame is at the second-moment closure (SMC) level. Although SMCs naturally accounts for the effects of system rotation, the usual application of a scalar dissipation rate equation is shown to require ad hoc corrections in some cases in order to give good results. The elliptic relaxation approach is also used in conjunction with non-linear pressure-strain models and very encouraging results are obtained for rotating flows. Rotational induced secondary motions are vital to predicting the effects of system rotation. Some severe weaknesses of non-linear pressure-strain models are also indicated. Finally, a modelling methodology for anisotropic dissipation in nearly homogeneous turbulence are proposed. 84 refs., 56 figs., 16 tabs.

  5. Measurement of Resistive Wall Mode stability in rotating high beta plasmas

    International Nuclear Information System (INIS)

    Reimerdes, H.; Bialek, J.; Garofalo, A.M.; Navratil, G.A.; Chance, M.S.; Menard, J.E.; Okabayashi, M.; Takahashi, H.; Chu, M.S.; Gohil, P.; Jackson, G.L.; Jensen, T.H.; La Haye, R.J.; Scoville, J.T.; Strait, E.J.; Jayakumar, R.J.; Liu, Y.Q.

    2005-01-01

    Toroidal plasma rotation in the order of a few percent of the Alfven velocity can stabilize the resistive wall mode and extend the operating regime of tokamaks from the conventional, ideal MHD no-wall limit up to the ideal MHD ideal wall limit. The stabilizing effect has been measured passively by measuring the critical plasma rotation required for stability and actively by probing the plasma with externally applied resonant magnetic fields. These measurements are compared to predictions of rotational stabilization of the sound wave damping and of the kinetic damping model using the MARS code. (author)

  6. Laminar boundary layer near the rotating end wall of a confined vortex

    Science.gov (United States)

    Shakespeare, W. J.; Levy, E. K.

    1982-06-01

    The results of an experimental and theoretical investigation of the fluid mechanics in a confined vortex are discussed with particular emphasis on behavior away from the axis of symmetry and near the end walls. The vortex is generated in a rotating cylindrical chamber with an exit opening in one end. Both end walls rotate. For the range of flow rates and swirl ratios (S between 1 and 5) of interest here, the flow field far from the end walls behaves as inviscid and irrotational; and the end wall boundary layers are thin and laminar. Measurements and calculations of tangential and radial velocity in the end wall region show the development of a secondary flow resulting in a strong velocity 'overshoot' in the radial component. Results illustrating the nature of the velocity variations on the end walls are presented; and it is shown that the mass flow rate through the end wall boundary layers, while only a small fraction of the total flow, increases with increasing swirl and with decreasing total flow rate through the chamber.

  7. The bacterial actin MreB rotates, and rotation depends on cell-wall assembly.

    Science.gov (United States)

    van Teeffelen, Sven; Wang, Siyuan; Furchtgott, Leon; Huang, Kerwyn Casey; Wingreen, Ned S; Shaevitz, Joshua W; Gitai, Zemer

    2011-09-20

    Bacterial cells possess multiple cytoskeletal proteins involved in a wide range of cellular processes. These cytoskeletal proteins are dynamic, but the driving forces and cellular functions of these dynamics remain poorly understood. Eukaryotic cytoskeletal dynamics are often driven by motor proteins, but in bacteria no motors that drive cytoskeletal motion have been identified to date. Here, we quantitatively study the dynamics of the Escherichia coli actin homolog MreB, which is essential for the maintenance of rod-like cell shape in bacteria. We find that MreB rotates around the long axis of the cell in a persistent manner. Whereas previous studies have suggested that MreB dynamics are driven by its own polymerization, we show that MreB rotation does not depend on its own polymerization but rather requires the assembly of the peptidoglycan cell wall. The cell-wall synthesis machinery thus either constitutes a novel type of extracellular motor that exerts force on cytoplasmic MreB, or is indirectly required for an as-yet-unidentified motor. Biophysical simulations suggest that one function of MreB rotation is to ensure a uniform distribution of new peptidoglycan insertion sites, a necessary condition to maintain rod shape during growth. These findings both broaden the view of cytoskeletal motors and deepen our understanding of the physical basis of bacterial morphogenesis.

  8. RodZ links MreB to cell wall synthesis to mediate MreB rotation and robust morphogenesis.

    Science.gov (United States)

    Morgenstein, Randy M; Bratton, Benjamin P; Nguyen, Jeffrey P; Ouzounov, Nikolay; Shaevitz, Joshua W; Gitai, Zemer

    2015-10-06

    The rod shape of most bacteria requires the actin homolog, MreB. Whereas MreB was initially thought to statically define rod shape, recent studies found that MreB dynamically rotates around the cell circumference dependent on cell wall synthesis. However, the mechanism by which cytoplasmic MreB is linked to extracytoplasmic cell wall synthesis and the function of this linkage for morphogenesis has remained unclear. Here we demonstrate that the transmembrane protein RodZ mediates MreB rotation by directly or indirectly coupling MreB to cell wall synthesis enzymes. Furthermore, we map the RodZ domains that link MreB to cell wall synthesis and identify mreB mutants that suppress the shape defect of ΔrodZ without restoring rotation, uncoupling rotation from rod-like growth. Surprisingly, MreB rotation is dispensable for rod-like shape determination under standard laboratory conditions but is required for the robustness of rod shape and growth under conditions of cell wall stress.

  9. Reduced critical rotation for resistive-wall mode stabilization in a near-axisymmetric configuration.

    Science.gov (United States)

    Reimerdes, H; Garofalo, A M; Jackson, G L; Okabayashi, M; Strait, E J; Chu, M S; In, Y; La Haye, R J; Lanctot, M J; Liu, Y Q; Navratil, G A; Solomon, W M; Takahashi, H; Groebner, R J

    2007-02-02

    Recent DIII-D experiments with reduced neutral beam torque and minimum nonaxisymmetric perturbations of the magnetic field show a significant reduction of the toroidal plasma rotation required for the stabilization of the resistive-wall mode (RWM) below the threshold values observed in experiments that apply nonaxisymmetric magnetic fields to slow the plasma rotation. A toroidal rotation frequency of less than 10 krad/s at the q=2 surface (measured with charge exchange recombination spectroscopy using C VI) corresponding to 0.3% of the inverse of the toroidal Alfvén time is sufficient to sustain the plasma pressure above the ideal MHD no-wall stability limit. The low-rotation threshold is found to be consistent with predictions by a kinetic model of RWM damping.

  10. Calculation of Ground State Rotational Populations for Kinetic Gas Homonuclear Diatomic Molecules including Electron-Impact Excitation and Wall Collisions

    International Nuclear Information System (INIS)

    Farley, David R.

    2010-01-01

    A model has been developed to calculate the ground-state rotational populations of homonuclear diatomic molecules in kinetic gases, including the effects of electron-impact excitation, wall collisions, and gas feed rate. The equations are exact within the accuracy of the cross sections used and of the assumed equilibrating effect of wall collisions. It is found that the inflow of feed gas and equilibrating wall collisions can significantly affect the rotational distribution in competition with non-equilibrating electron-impact effects. The resulting steady-state rotational distributions are generally Boltzmann for N (ge) 3, with a rotational temperature between the wall and feed gas temperatures. The N = 0,1,2 rotational level populations depend sensitively on the relative rates of electron-impact excitation versus wall collision and gas feed rates.

  11. Illinois Walls in alternative market structures

    NARCIS (Netherlands)

    Schinkel, M.P.; Tuinstra, J.

    2005-01-01

    This note extends on our paper Illinois Walls: How Barring Indirect Purchaser Suits Facilitates Collusion (Schinkel, Tuinstra and Rüggeberg, 2005, henceforth STR). It presents analyses of two alternative, more competitive, market structures to conclude that when the conditions for existence of

  12. Stabilization of thin shell modes by a rotating secondary wall

    International Nuclear Information System (INIS)

    Gimblett, C.G.

    1989-01-01

    A simple model is developed to investigate if and under what circumstances the thin shell instabilities of a Reverse Field Pinch can be stabilized by a rotating secondary wall. The principles may be applicable to reactor designs that utilize a flowing liquid blanket (author)

  13. Alternative to domain wall fermions

    International Nuclear Information System (INIS)

    Neuberger, H.

    2002-01-01

    An alternative to commonly used domain wall fermions is presented. Some rigorous bounds on the condition number of the associated linear problem are derived. On the basis of these bounds and some experimentation it is argued that domain wall fermions will in general be associated with a condition number that is of the same order of magnitude as the product of the condition number of the linear problem in the physical dimensions by the inverse bare quark mass. Thus, the computational cost of implementing true domain wall fermions using a single conjugate gradient algorithm is of the same order of magnitude as that of implementing the overlap Dirac operator directly using two nested conjugate gradient algorithms. At a cost of about a factor of two in operation count it is possible to make the memory usage of direct implementations of the overlap Dirac operator independent of the accuracy of the approximation to the sign function and of the same order as that of standard Wilson fermions

  14. Feedback and rotational stabilization of resistive wall modes in ITER

    International Nuclear Information System (INIS)

    Liu Yueqiang; Bondeson, A.; Chu, M.S.; La Haye, R.J.; Favez, J.-Y.; Lister, J.B.; Gribov, Y.; Gryaznevich, M.; Hender, T.C.; Howell, D.F.

    2005-01-01

    Different models have been introduced in the stability code MARS-F in order to study the damping effect of resistive wall modes (RWM) in rotating plasmas. Benchmark of MARS-F calculations with RWM experiments on JET and D3D indicates that the semi-kinetic damping model is a good candidate for explaining the damping mechanisms. Based on these results, the critical rotation speeds required for RWM stabilization in an advanced ITER scenario are predicted. Active feedback control of the n = 1 RWM in ITER is also studied using the MARS-F code. (author)

  15. Lateral Earth Pressure behind Walls Rotating about Base considering Arching Effects

    Directory of Open Access Journals (Sweden)

    Dong Li

    2014-01-01

    Full Text Available In field, the earth pressure on a retaining wall is the common effect of kinds of factors. To figure out how key factors act, it has taken into account the arching effects together with the contribution from the mode of displacement of a wall to calculate earth pressure in the proposed method. Based on Mohr circle, a conversion factor is introduced to determine the shear stresses between artificial slices in soil mass. In the light of this basis, a modified differential slices solution is presented for calculation of active earth pressure on a retaining wall. Comparisons show that the result of proposed method is identical to observations from model tests in prediction of lateral pressures for walls rotating about the base.

  16. Stability of ideal and resistive modes in cylindrical plasmas with resistive walls and plasma rotation

    International Nuclear Information System (INIS)

    Bondeson, A.; Xie, H.X.

    1996-01-01

    The stabilization of cylindrical plasmas by resistive walls combined with plasma rotation is analyzed. Perturbations with a single mode rational surface q=m/n in a finitely conducting plasma are treated by the resistive kink dispersion relation of Coppi. The possibilities for stabilization of ideal and resistive instabilities are explored systematically in different regions of parameter space. The study confirms that an ideal instability can be stabilized by a close-fitting wall and a rotation velocity of the order of resistive growth rate. However, the region in parameter space where such stabilization occurs is very small and appears to be difficult to exploit in experiments. The overall conclusion from the cylindrical plasma model is that resistive modes can readily be wall stabilized, whereas complete wall stabilization is hard to achieve for plasmas that are ideally unstable with the wall at infinity. 26 refs, 5 figs

  17. Vorticity generation and wake transition for a translating circular cylinder: Wall proximity and rotation effects

    DEFF Research Database (Denmark)

    Hourigan, K.; Rao, A.; Brøns, Morten

    2013-01-01

    The wake transitions of generic bluff bodies, such as a circular cylinder, near a wall are important because they provide understanding of different transition paths towards turbulence, and give some insight into the effect of surface modifications on the flow past larger downstream structures......-annihilate with opposite-signed vorticity, and can be stored at a free surface, thus conserving the total vorticity, or circulation. Vorticity generation, diffusion and storage are demonstrated for a cylinder translating and rotating near a wall. The wake characteristics and the wake transitions are shown to change...... dramatically under the influence of cylinder rotation and wall proximity. At gaps between the cylinder and the wall of less than approximately 0.25 cylinder diameter, the wake becomes three dimensional prior to becoming unsteady, while for larger gaps the initial transition is to an unsteady two...

  18. Resistive wall mode stabilization in slowly rotating high beta plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Reimerdes, H [Columbia University, New York, NY 10027 (United States); Garofalo, A M [Columbia University, New York, NY 10027 (United States); Okabayashi, M [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States); Strait, E J [General Atomics, San Diego, CA 92186-5608 (United States); Betti, R [University of Rochester, Rochester, NY 14627 (United States); Chu, M S [General Atomics, San Diego, CA 92186-5608 (United States); Hu, B [University of Rochester, Rochester, NY 14627 (United States); In, Y [FAR-TECH, Inc., San Diego, CA 92121 (United States); Jackson, G L [General Atomics, San Diego, CA 92186-5608 (United States); La Haye, R J [General Atomics, San Diego, CA 92186-5608 (United States); Lanctot, M J [Columbia University, New York, NY 10027 (United States); Liu, Y Q [Chalmers University of Technology, S-412 96 Goeteborg (Sweden); Navratil, G A [Columbia University, New York, NY 10027 (United States); Solomon, W M [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States); Takahashi, H [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States); Groebner, R J [General Atomics, San Diego, CA 92186-5608 (United States)

    2007-12-15

    DIII-D experiments show that the resistive wall mode (RWM) can remain stable in high {beta} scenarios despite a low net torque from nearly balanced neutral beam injection heating. The minimization of magnetic field asymmetries is essential for operation at the resulting low plasma rotation of less than 20 krad s{sup -1} (measured with charge exchange recombination spectroscopy using C VI emission) corresponding to less than 1% of the Alfven velocity or less than 10% of the ion thermal velocity. In the presence of n = 1 field asymmetries the rotation required for stability is significantly higher and depends on the torque input and momentum confinement, which suggests that a loss of torque-balance can lead to an effective rotation threshold above the linear RWM stability threshold. Without an externally applied field the measured rotation can be too low to neglect the diamagnetic rotation. A comparison of the instability onset in plasmas rotating with and against the direction of the plasma current indicates the importance of the toroidal flow driven by the radial electric field in the stabilization process. Observed rotation thresholds are compared with predictions for the semi-kinetic damping model, which generally underestimates the rotation required for stability. A more detailed modeling of kinetic damping including diamagnetic and precession drift frequencies can lead to stability without plasma rotation. However, even with corrected error fields and fast plasma rotation, plasma generated perturbations, such as edge localized modes, can nonlinearly destabilize the RWM. In these cases feedback control can increase the damping of the magnetic perturbation and is effective in extending the duration of high {beta} discharges.

  19. Turbulence modifications in a turbulent boundary layer over a rough wall with spanwise-alternating roughness strips

    Science.gov (United States)

    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.

  20. Effect of wall conductances on hydromagnetic flow and heat transfer in a rotating channel

    International Nuclear Information System (INIS)

    Mazumder, B.S.

    1977-01-01

    Wall conductance effects on the hydromagnetic flow and heat transfer between two parallel plates in a rotating frame of reference has been studied when the liquid is permeated by a transverse magnetic field. An exact solution of the governing equation has been obtained. It is found that the velocity current density and the temperature depend only on the sum of the wall conductances phi 1 + phi 2 = phi but magnetic field depends on the individual values of phi 1 and phi 2 where phi 1 and phi 2 are respectively the wall conductance ratios of the upper and lower walls. (Auth.)

  1. Axial slit wall effect on the flow instability and heat transfer in rotating concentric cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Dong; Chao, Chang Qing; Wang, Ying Ze; Zhu, Fang Neng [School of Energy and Power Engineering, Jiangsu University, Zhenjiang (China); Kim, Hyoung Bum [School of Mechanical and Aerospace Engineering, Gyeongsang National University, Jinju (Korea, Republic of)

    2016-12-15

    The slit wall effect on the flow instability and heat transfer characteristics in Taylor-Couette flow was numerically studied by changing the rotating Reynolds number and applying the negative temperature gradient. The concentric cylinders with slit wall are seen in many rotating machineries. Six different models with the slit number 0, 6, 9, 12, 15 and 18 were investigated in this study. The results show the axial slit wall enhances the Taylor vortex flow and suppresses the azimuthal variation of wavy Taylor vortex flow. When negative temperature gradient exists, the results show that the heat transfer augmentation appears from laminar Taylor vortex to turbulent Taylor flow regime. The heat transfer enhancement become stronger as increasing the Reynolds number and slit number. The larger slit number model also accelerates the flow transition regardless of the negative temperature gradient or isothermal condition.

  2. Axial slit wall effect on the flow instability and heat transfer in rotating concentric cylinders

    International Nuclear Information System (INIS)

    Liu, Dong; Chao, Chang Qing; Wang, Ying Ze; Zhu, Fang Neng; Kim, Hyoung Bum

    2016-01-01

    The slit wall effect on the flow instability and heat transfer characteristics in Taylor-Couette flow was numerically studied by changing the rotating Reynolds number and applying the negative temperature gradient. The concentric cylinders with slit wall are seen in many rotating machineries. Six different models with the slit number 0, 6, 9, 12, 15 and 18 were investigated in this study. The results show the axial slit wall enhances the Taylor vortex flow and suppresses the azimuthal variation of wavy Taylor vortex flow. When negative temperature gradient exists, the results show that the heat transfer augmentation appears from laminar Taylor vortex to turbulent Taylor flow regime. The heat transfer enhancement become stronger as increasing the Reynolds number and slit number. The larger slit number model also accelerates the flow transition regardless of the negative temperature gradient or isothermal condition

  3. No rotating U.S. Testing of thin walled tubes

    International Nuclear Information System (INIS)

    Furlan, J.; Boulanger, G.; Mogavero, R.

    1981-07-01

    Thin walled tube ultrasonic testing is performed, with Lamb waves, using annular transducers and conical or helicoidal mirrors. The main advantage of this already known system is dispensing with rotation of tube and/or transducer. High speed control (30 cm/s and more) is then allowed. The present paper describes the parameters influencing the sensitivity has been improved by searching, theoretically and practically, the best suited Lamb wave modes, and by using transducers which are well characterized. Practical example of cladding tube U.S. testing is described

  4. Weed control through crop rotation and alternative management practices

    Directory of Open Access Journals (Sweden)

    Böhm, Herwart

    2014-02-01

    Full Text Available Economic as well as agricultural and socio-political changes have an impact on crop management and thus also on crop rotation design and the related effects on the weed flora. Likewise other changes in cultivation such as reduced tillage practices, earlier sowing date, etc. cause an increase in weed infestation resp. an increased use of herbicides and if so contribute to herbicide resistance. The positive effects of crop rotation, but also of alternative management practices such as choice of varieties, catch crops, mixed cropping, green chop, and the share of predators, as well as methods of direct non-chemical weed control are presented and discussed for both, conventional and organic farming. If alternative management methods should be more practiced, especially trade-offs need to be broken, or incentives be offered.

  5. The influence of the tangential velocity of inner rotating wall on axial velocity profile of flow through vertical annular pipe with rotating inner surface

    Directory of Open Access Journals (Sweden)

    Sharf Abdusalam M.

    2014-03-01

    Full Text Available In the oil and gas industries, understanding the behaviour of a flow through an annulus gap in a vertical position, whose outer wall is stationary whilst the inner wall rotates, is a significantly important issue in drilling wells. The main emphasis is placed on experimental (using an available rig and computational (employing CFD software investigations into the effects of the rotation speed of the inner pipe on the axial velocity profiles. The measured axial velocity profiles, in the cases of low axial flow, show that the axial velocity is influenced by the rotation speed of the inner pipe in the region of almost 33% of the annulus near the inner pipe, and influenced inversely in the rest of the annulus. The position of the maximum axial velocity is shifted from the centre to be nearer the inner pipe, by increasing the rotation speed. However, in the case of higher flow, as the rotation speed increases, the axial velocity is reduced and the position of the maximum axial velocity is skewed towards the centre of the annulus. There is a reduction of the swirl velocity corresponding to the rise of the volumetric flow rate.

  6. Impact of scaffold micro and macro architecture on Schwann cell proliferation under dynamic conditions in a rotating wall vessel bioreactor

    International Nuclear Information System (INIS)

    Valmikinathan, Chandra M.; Hoffman, John; Yu, Xiaojun

    2011-01-01

    Over the last decade tissue engineering has emerged as a powerful alternative to regenerate lost tissues owing to trauma or tumor. Evidence shows that Schwann cell containing scaffolds have improved performance in vivo as compared to scaffolds that depend on cellularization post implantation. However, owing to limited supply of cells from the patients themselves, several approaches have been taken to enhance cell proliferation rates to produce complete and uniform cellularization of scaffolds. The most common approach is the application of a bioreactor to enhance cell proliferation rate and therefore reduce the time needed to obtain sufficiently significant number of glial cells, prior to implantation. In this study, we show the application of a rotating wall bioreactor system for studying Schwann cell proliferation on nanofibrous spiral shaped scaffolds, prepared by solvent casting and salt leaching techniques. The scaffolds were fabricated from polycaprolactone (PCL), which has ideal mechanical properties and upon degradation does not produce acidic byproducts. The spiral scaffolds were coated with aligned or random nanofibers, produced by electrospinning, to provide a substrate that mimics the native extracellular matrix and the essential contact guidance cues. At the 4 day time point, an enhanced rate of cell proliferation was observed on the open structured nanofibrous spiral scaffolds in a rotating wall bioreactor, as compared to static culture conditions. However, the cell proliferation rate on the other contemporary scaffolds architectures such as the tubular and cylindrical scaffolds show reduced cell proliferation in the bioreactor as compared to static conditions, at the same time point. Moreover, the rotating wall bioreactor does not alter the orientation or the phenotype of the Schwann cells on the aligned nanofiber containing scaffolds, wherein, the cells remain aligned along the length of the scaffolds. Therefore, these open structured spiral

  7. Interplay of domain walls and magnetization rotation on dynamic magnetization process in iron/polymer–matrix soft magnetic composites

    Energy Technology Data Exchange (ETDEWEB)

    Dobák, Samuel, E-mail: samuel.dobak@student.upjs.sk [Institute of Physics, Faculty of Science, Pavol Jozef Šafárik University, Park Angelinum 9, 041 54 Košice (Slovakia); Füzer, Ján; Kollár, Peter [Institute of Physics, Faculty of Science, Pavol Jozef Šafárik University, Park Angelinum 9, 041 54 Košice (Slovakia); Fáberová, Mária; Bureš, Radovan [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 043 53 Košice (Slovakia)

    2017-03-15

    This study sheds light on the dynamic magnetization process in iron/resin soft magnetic composites from the viewpoint of quantitative decomposition of their complex permeability spectra into the viscous domain wall motion and magnetization rotation. We present a comprehensive view on this phenomenon over the broad family of samples with different average particles dimension and dielectric matrix content. The results reveal the pure relaxation nature of magnetization processes without observation of spin resonance. The smaller particles and higher amount of insulating resin result in the prevalence of rotations over domain wall movement. The findings are elucidated in terms of demagnetizing effects rising from the heterogeneity of composite materials. - Highlights: • A first decomposition of complex permeability into domain wall and rotation parts in soft magnetic composites. • A pure relaxation nature of dynamic magnetization processes. • A complete loss separation in soft magnetic composites. • The domain walls activity is considerably suppressed in composites with smaller iron particles and higher matrix content. • The demagnetizing field acts as a significant factor at the dynamic magnetization process.

  8. The Rolling Transition in a Granular Flow along a Rotating Wall

    Directory of Open Access Journals (Sweden)

    Aurélie Le Quiniou

    2011-11-01

    Full Text Available The flow of a dry granular material composed of spherical particles along a rotating boundary has been studied by the discrete element method (DEM. This type of flow is used, among others, as a process to spread particles. The flow consists of several phases. A compression phase along the rotating wall is followed by an elongation of the flow along the same boundary. Eventually, the particles slide or roll independently along the boundary. We show that the main motion of the flow can be characterized by a complex deformation rate of traction/compression and shear. We define numerically an effective friction coefficient of the flow on the scale of the continuum and show a strong decrease of this effective friction beyond a certain critical friction coefficient μ*. We correlate this phenomenon with the apparition of a new transition from a sliding regime to a rolling without sliding regime that we called the rolling transition; this dynamic transition is controlled by the value of the friction coefficient between the particle and the wall. We show that the spherical shape for the particles may represent an optimum for the flow in terms of energetic.

  9. Rotating solitary wave at the wall of a cylindrical container

    KAUST Repository

    Amaouche, Mustapha

    2013-04-30

    This paper deals with the theoretical modeling of a rotating solitary surface wave that was observed during water drainage from a cylindrical reservoir, when shallow water conditions were reached. It represents an improvement of our previous study, where the radial flow perturbation was neglected. This assumption led to the classical planar Korteweg–de Vries equation for the wall wave profile, which did not account for the rotational character of the base flow. The present formulation is based on a less restricting condition and consequently corrects the last shortcoming. Now the influence of the background flow appears in the wave characteristics. The theory provides a better physical depiction of the unique experiment by predicting fairly well the wave profile at least in the first half of its lifetime and estimating the speed of the observed wave with good accuracy.

  10. Thermocapillary instabilities in a laterally heated liquid bridge with end wall rotation

    Science.gov (United States)

    Kahouadji, L.; Houchens, B. C.; Witkowski, L. Martin

    2011-10-01

    The effect of rotation on the stability of thermocapillary driven flow in a laterally heated liquid bridge is studied numerically using the full-zone model of the floating-zone crystal growth technique. A small Prandtl number (0.02) fluid, relevant for semiconductor melts, is studied with an aspect ratio (height to diameter of the melt) equal to one. Buoyancy is neglected. A linear stability analysis of three-dimensional perturbations is performed and shows that for any ratio of angular velocities, a weak rotation rate has the surprising effect of destabilizing the base flow. By systematically varying the rotation rate and ratio of angular velocities, the critical threshold and azimuthal wave number of the most unstable mode is found over a wide range of this two parameter space. Depending on these parameters, the leading eigenmode is a wave propagating either in the positive or negative azimuthal direction, with kinetic energy typically localized close to one of the end walls. These results are of practical interest for industrial crystal growth applications, where rotation is often used to obtain higher quality crystals.

  11. Intrinsic rotation due to MHD activity in a tokamak with a resistive wall

    International Nuclear Information System (INIS)

    Haines, M G; Gimblett, C G; Hastie, R J

    2013-01-01

    MHD activity in a tokamak, in the form of waves and instabilities, generally has a preferred direction for propagation in a two-fluid plasma. When the radial component of magnetic field associated with this activity interacts with a resistive wall, momentum or angular momentum will be given to the wall. The equal and opposite reaction will be on the plasma, in particular, for ideal and resistive modes, at the singular or resonant surfaces for the various modes. In this case the torque exerted is electromagnetic. This is in contrast to other mechanisms for intrinsic or spontaneous rotation which may arise at the plasma boundary. The resistive wall is considered generally, and the thin and thick wall limits found, the latter being relevant to ITER parameters. Remarkably small radial perturbing fields of order 0.1 G could produce a torque comparable in effect to the apparent anomalous toroidal viscosity. (paper)

  12. Characterization of counter-rotating streamwise vortices in flat rectangular channel with one-sided wavy wall

    KAUST Repository

    Bouremel, Yann

    2016-11-01

    Particle Image Velocimetry (PIV) has been used to characterize the evolution of counter-rotating streamwise vortices in a rectangular channel with one sided wavy surface. The vortices were created by a uniform set of saw-tooth carved over the leading edge of a flat plate at the entrance of a flat rectangular channel with one-sided wavy wall. PIV measurements were taken over the spanwise and streamwise planes at different locations and at Reynolds number of 2500. Two other Reynolds numbers of 2885 and 3333 have also been considered for quantification purpose. Pairs of counter-rotating streamwise vortices have been shown experimentally to be centred along the spanwise direction at the saw-tooth valley where the vorticity ωz=0ωz=0. It has also been found that the vorticity ωzωz of the pairs of counter-rotating vortices decreases along the streamwise direction, and increases with the Reynolds number. Moreover, different quantifications of such counter-rotating vortices have been discussed such as their size, boundary layer, velocity profile and vorticity. The current study shows that the mixing due to the wall shear stress of counter-rotating streamwise vortices as well as their averaged viscous dissipation rate of kinetic energy decrease over flat and adverse pressure gradient surfaces while increasing over favourable pressure gradient surfaces. Finally, it was also demonstrated that the main direction of stretching is orientated at around 45° with the main flow direction.

  13. Characterization of counter-rotating streamwise vortices in flat rectangular channel with one-sided wavy wall

    KAUST Repository

    Bouremel, Yann; Mitsudharmadi, Hatsari; Budiman, Alexander C.; Winoto, Sonny H.

    2016-01-01

    Particle Image Velocimetry (PIV) has been used to characterize the evolution of counter-rotating streamwise vortices in a rectangular channel with one sided wavy surface. The vortices were created by a uniform set of saw-tooth carved over the leading edge of a flat plate at the entrance of a flat rectangular channel with one-sided wavy wall. PIV measurements were taken over the spanwise and streamwise planes at different locations and at Reynolds number of 2500. Two other Reynolds numbers of 2885 and 3333 have also been considered for quantification purpose. Pairs of counter-rotating streamwise vortices have been shown experimentally to be centred along the spanwise direction at the saw-tooth valley where the vorticity ωz=0ωz=0. It has also been found that the vorticity ωzωz of the pairs of counter-rotating vortices decreases along the streamwise direction, and increases with the Reynolds number. Moreover, different quantifications of such counter-rotating vortices have been discussed such as their size, boundary layer, velocity profile and vorticity. The current study shows that the mixing due to the wall shear stress of counter-rotating streamwise vortices as well as their averaged viscous dissipation rate of kinetic energy decrease over flat and adverse pressure gradient surfaces while increasing over favourable pressure gradient surfaces. Finally, it was also demonstrated that the main direction of stretching is orientated at around 45° with the main flow direction.

  14. Saccharomyces cerevisiae gene expression changes during rotating wall vessel suspension culture

    Science.gov (United States)

    Johanson, Kelly; Allen, Patricia L.; Lewis, Fawn; Cubano, Luis A.; Hyman, Linda E.; Hammond, Timothy G.

    2002-01-01

    This study utilizes Saccharomyces cerevisiae to study genetic responses to suspension culture. The suspension culture system used in this study is the high-aspect-ratio vessel, one type of the rotating wall vessel, that provides a high rate of gas exchange necessary for rapidly dividing cells. Cells were grown in the high-aspect-ratio vessel, and DNA microarray and metabolic analyses were used to determine the resulting changes in yeast gene expression. A significant number of genes were found to be up- or downregulated by at least twofold as a result of rotational growth. By using Gibbs promoter alignment, clusters of genes were examined for promoter elements mediating these genetic changes. Candidate binding motifs similar to the Rap1p binding site and the stress-responsive element were identified in the promoter regions of differentially regulated genes. This study shows that, as in higher order organisms, S. cerevisiae changes gene expression in response to rotational culture and also provides clues for investigations into the signaling pathways involved in gravitational response.

  15. Influence of rotating in-plane field on vertical Bloch lines in the walls of second kind of dumbbell domains

    International Nuclear Information System (INIS)

    Sun, H.Y.; Hu, H.N.; Sun, Y.P.; Nie, X.F.

    2004-01-01

    Influence of rotating in-plane field on vertical Bloch lines in the walls of second kind of dumbbell domains (IIDs) was investigated, and a critical in-plane field range [H ip 1 ,H ip 2 ] of which vertical-Bloch lines (VBLs) annihilated in IIDs is found under rotating in-plane field (H ip 1 is the maximal critical in-plane-field of which hard domains remain stable, H ip 2 is the minimal critical in-plane-field of which all of the hard domains convert to soft bubbles (SBs, without VBLs)). It shows that the in-plane field range [H ip 1 , H ip 2 ] changes with the change of the rotating angle Δφ H ip 1 maintains stable, while H ip 2 decreases with the decreasing of rotating angle Δφ. Comparing it with the spontaneous shrinking experiment of IIDs under both bias field and in-plane field, we presume that under the application of in-plane field there exists a direction along which the VBLs in the domain walls annihilate most easily, and it is in the direction that domain walls are perpendicular to the in-plane field

  16. Magnetoexcitons and Faraday rotation in single-walled carbon nanotubes and graphene nanoribbons

    Science.gov (United States)

    Have, Jonas; Pedersen, Thomas G.

    2018-03-01

    The magneto-optical response of single-walled carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) is studied theoretically, including excitonic effects. Both diagonal and nondiagonal response functions are obtained and employed to compute Faraday rotation spectra. For single-walled CNTs in a parallel field, the results show field-dependent splitting of the exciton absorption peaks caused by brightening a dark exciton state. Similarly, for GNRs in a perpendicular magnetic field, we observe a field-dependent shift of the exciton peaks and the emergence of an absorption peak above the energy gap. Results show that excitonic effects play a significant role in the optical response of both materials, particularly for the off-diagonal tensor elements.

  17. Wall shear stress from a rotating cylinder in cross flow using the electrochemical technique

    International Nuclear Information System (INIS)

    Labraga, L.; Bourabaa, N.; Berkah, T.

    2002-01-01

    The wall shear rate from a rotating cylinder in a uniform flow was measured with flush-mounted electrochemical mass transfer probes. The experiments were performed using two rectangular electrodes in a sandwich arrangement. Initially, the frequency response of that probe was numerically studied using an inverse mass transfer method in order to restore the whole wall shear stress in the time domain starting from the measured transfer coefficients given by the split probe. The experiments were performed in the range of velocity ratios 0 4, points of zero shear stress on the rotating cylinder vanish, which is in fact consistent with the previous arguments that the cylinder is surrounded by a set of closed streamlines. This experimental study shows that, when their dynamic behaviour is known, the electrochemical probes are able to sense complex fine structures not observed up to now by previous analytical, numerical or experimental methods, even when non-linear effects are not negligible. (orig.)

  18. Contributions of the wall boundary layer to the formation of the counter-rotating vortex pair in transverse jets

    KAUST Repository

    SCHLEGEL, FABRICE

    2011-04-08

    Using high-resolution 3-D vortex simulations, this study seeks a mechanistic understanding of vorticity dynamics in transverse jets at a finite Reynolds number. A full no-slip boundary condition, rigorously formulated in terms of vorticity generation along the channel wall, captures unsteady interactions between the wall boundary layer and the jet - in particular, the separation of the wall boundary layer and its transport into the interior. For comparison, we also implement a reduced boundary condition that suppresses the separation of the wall boundary layer away from the jet nozzle. By contrasting results obtained with these two boundary conditions, we characterize near-field vortical structures formed as the wall boundary layer separates on the backside of the jet. Using various Eulerian and Lagrangian diagnostics, it is demonstrated that several near-wall vortical structures are formed as the wall boundary layer separates. The counter-rotating vortex pair, manifested by the presence of vortices aligned with the jet trajectory, is initiated closer to the jet exit. Moreover tornado-like wall-normal vortices originate from the separation of spanwise vorticity in the wall boundary layer at the side of the jet and from the entrainment of streamwise wall vortices in the recirculation zone on the lee side. These tornado-like vortices are absent in the case where separation is suppressed. Tornado-like vortices merge with counter-rotating vorticity originating in the jet shear layer, significantly increasing wall-normal circulation and causing deeper jet penetration into the crossflow stream. © 2011 Cambridge University Press.

  19. Effects of Simulated Microgravity on Otolith Growth of Larval Zebrafish using a Rotating-Wall Vessel: Appropriate Rotation Speed and Fish Developmental Stage

    Science.gov (United States)

    Li, Xiaoyan; Anken, Ralf; Liu, Liyue; Wang, Gaohong; Liu, Yongding

    2017-02-01

    Stimulus dependence is a general feature of developing animal sensory systems. In this respect, it has extensively been shown earlier that fish inner ear otoliths can act as test masses as their growth is strongly affected by altered gravity such as hypergravity obtained using centrifuges, by (real) microgravity achieved during spaceflight or by simulated microgravity using a ground-based facility. Since flight opportunities are scarce, ground-based simulators of microgravity, using a wide variety of physical principles, have been developed to overcome this shortcoming. Not all of them, however, are equally well suited to provide functional weightlessness from the perspective of the biosystem under evaluation. Therefore, the range of applicability of a particular simulator has to be extensively tested. Earlier, we have shown that a Rotating-Wall Vessel (RWV) can be used to provide simulated microgravity for developing Zebrafish regarding the effect of rotation on otolith development. In the present study, we wanted to find the most effective speed of rotation and identify the appropriate developmental stage of Zebrafish, where effects are the largest, in order to provide a methodological basis for future in-depth analyses dedicated to the physiological processes underlying otolith growth at altered gravity. Last not least, we compared data on the effect of simulated microgravity on the size versus the weight of otoliths, since the size usually is measured in related studies due to convenience, but the weight more accurately approximates the physical capacity of an otolith. Maintaining embryos at 10 hours post fertilization for three days in the RWV, we found that 15 revolutions per minute (rpm) yielded the strongest effects on otolith growth. Maintenance of Zebrafish staged at 10 hpf, 1 day post fertilization (dpf), 4 dpf, 7 dpf and 14 dpf for three days at 15 rpm resulted in the most prominent effects in 7 dpf larvae. Weighing versus measuring the size of otoliths

  20. Analytical modelling of resistive wall mode stabilization by rotation in toroidal tokamak plasmas

    International Nuclear Information System (INIS)

    Ham, C J; Gimblett, C G; Hastie, R J

    2011-01-01

    Stabilization of the resitive wall mode (RWM) may allow fusion power to be doubled for a given magnetic field in advanced tokamak operation. Experimental evidence from DIII-D and other machines suggests that plasma rotation can stabilize the RWM. Several authors (Finn 1995 Phys. Plasmas 2 3782, Bondeson and Xie 1997 Phys. Plasmas 4 2081) have constructed analytical cylindrical models for the RWM, but these do not deal with toroidal effects. The framework of Connor et al (1988 Phys. Fluids 31 577) is used to develop ideal plasma analytic models with toroidicity included. Stepped pressure profiles and careful ordering of terms are used to simplify the analysis. First, a current driven kink mode model is developed and a dispersion relation for arbitrary current profile is calculated. Second, the external pressure driven kink mode is similarly investigated as the most important RWM arises from this mode. Using this latter model it is found that the RWM is stabilized by Alfven continuum damping with rotation levels similar to those seen in experiments. An expression for the stability of the external kink mode for more general current profiles and a resistive wall is derived in the appendix.

  1. Cell culture for three-dimensional modeling in rotating-wall vessels: an application of simulated microgravity

    Science.gov (United States)

    Schwarz, R. P.; Goodwin, T. J.; Wolf, D. A.

    1992-01-01

    High-density, three-dimensional cell cultures are difficult to grow in vitro. The rotating-wall vessel (RWV) described here has cultured BHK-21 cells to a density of 1.1 X 10(7) cells/ml. Cells on microcarriers were observed to grow with enhanced bridging in this batch culture system. The RWV is a horizontally rotated tissue culture vessel with silicon membrane oxygenation. This design results in a low-turbulence, low-shear cell culture environment with abundant oxygenation. The RWV has the potential to culture a wide variety of normal and neoplastic cells.

  2. The effect of partial poloidal wall sections on the wall stabilization of external kink modes

    International Nuclear Information System (INIS)

    Ward, D.J.

    1996-02-01

    An analysis of the effect on the wall stabilization of external kink modes due to toroidally continuous gaps in the resistive wall is performed. The effects with and without toroidal rotation are studied. For a high-β equilibrium, the mode structure is localized on the outboard side. Therefore, outboard gaps greatly increase the growth rate when there is no rotation. For resistive wall stabilization by toroidal rotation, the presence of gaps has the same effect as moving the wall farther away, i.e. destabilizing for the ideal plasma mode, and stabilizing for the resistive wall mode. The region of stability, in terms of wall position, is reduced in size and moved closer to the plasma. However, complete stabilization becomes possible at considerably reduced rotation frequencies. For a high-β, reverse-shear equilibrium both the resistive wall mode and the ideal plasma mode can be stabilized by close fitting discrete passive plates on the outboard side. The necessary toroidal rotation frequency to stabilize the resistive wall mode using these plates is reduced by a factor of three compared to that for a poloidally continuous and complete wall at the same plasma-wall separation. (author) 15 figs., 24 refs

  3. Osteocytes Mechanosensing in NASA Rotating Wall Bioreactor

    Science.gov (United States)

    Spatz, Jordan; Sibonga, Jean; Wu, Honglu; Barry, Kevin; Bouxsein, Mary; Pajevic, Paola Divieti

    2010-01-01

    Osteocyte cells are the most abundant (90%) yet least understood bone cell type in the human body. Osteocytes are theorized to be the mechanosensors and transducers of mechanical load for bones, yet the biological mechanism of this action remains elusive. However, recent discoveries in osteocyte cell biology have shed light on their importance as key mechanosensing cells regulating bone remodeling and phosphate homeostasis. The aim of this project was to characterize gene expression patterns and protein levels following exposure of MLO-Y4, a very well characterized murine osteocyte-like cell line, to simulated microgravity using the NASA Rotating Wall Vessel (RWV) Bioreactor. To determine mechanistic pathways of the osteocyte's gravity sensing ability, we evaluated in vitro gene and protein expression of osteocytes exposed to simulated microgravity. Improved understanding of the fundamental mechanisms of mechano transduction at the osteocyte cellular level may lead to revolutionary treatment otions to mitigate the effects of bone loss encountered by astronauts on long duration space missions and provide tailored treatment options for maintaining bone strength of immobilized/partially paralyzed patients here on Earth.

  4. Observations on resistive wall modes

    International Nuclear Information System (INIS)

    Gerwin, R.A.; Finn, J.M.

    1996-01-01

    Several results on resistive wall modes and their application to tokamaks are presented. First, it is observed that in the presence of collisional parallel dynamics there is an exact cancellation to lowest order of the dissipative and sound wave effects for an ideal Ohm's law. This is easily traced to the fact that the parallel dynamics occurs along the perturbed magnetic field lines for such electromagnetic modes. Such a cancellation does not occur in the resistive layer of a tearing-like mode. The relevance to models for resistive wall modes using an electrostatic Hammett-Perkins type operator to model Landau damping will be discussed. Second, we observe that with an ideal Ohm's law, resistive wall modes can be destabilized by rotation in that part of parameter space in which the ideal MHD modes are stable with the wall at infinity. This effect can easily be explained by interpreting the resistive wall instability in terms of mode coupling between the backward stable MHD mode and a stable mode locked into the wall. Such an effect can occur for very small rotation for tearing-resistive wall modes in which inertia dominates viscosity in the layer, but the mode is stabilized by further rotation. For modes for which viscosity dominates in the layer, rotation is purely stabilizing. For both tearing models, a somewhat higher rotation frequency gives stability essentially whenever the tearing mode is stable with a perfectly conducting wall. These tearing/resistive wall results axe also simply explained in terms of mode coupling. It has been shown that resonant external ideal modes can be stabilized in the presence of resistive wall and resistive plasma with rotation of order the nominal tearing mode growth rate. We show that these modes behave as resistive wall tearing modes in the sense above. This strengthens the suggestion that rotational stabilization of the external kink with a resistive wall is due to the presence of resistive layers, even for ideal modes

  5. Mixed convection heat transfer enhancement in a cubic lid-driven cavity containing a rotating cylinder through the introduction of artificial roughness on the heated wall

    Science.gov (United States)

    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.

  6. KRE5 Suppression Induces Cell Wall Stress and Alternative ER Stress Response Required for Maintaining Cell Wall Integrity in Candida glabrata

    Science.gov (United States)

    Sasaki, Masato; Ito, Fumie; Aoyama, Toshio; Sato-Okamoto, Michiyo; Takahashi-Nakaguchi, Azusa; Chibana, Hiroji; Shibata, Nobuyuki

    2016-01-01

    The maintenance of cell wall integrity in fungi is required for normal cell growth, division, hyphae formation, and antifungal tolerance. We observed that endoplasmic reticulum stress regulated cell wall integrity in Candida glabrata, which possesses uniquely evolved mechanisms for unfolded protein response mechanisms. Tetracycline-mediated suppression of KRE5, which encodes a predicted UDP-glucose:glycoprotein glucosyltransferase localized in the endoplasmic reticulum, significantly increased cell wall chitin content and decreased cell wall β-1,6-glucan content. KRE5 repression induced endoplasmic reticulum stress-related gene expression and MAP kinase pathway activation, including Slt2p and Hog1p phosphorylation, through the cell wall integrity signaling pathway. Moreover, the calcineurin pathway negatively regulated cell wall integrity, but not the reduction of β-1,6-glucan content. These results indicate that KRE5 is required for maintaining both endoplasmic reticulum homeostasis and cell wall integrity, and that the calcineurin pathway acts as a regulator of chitin-glucan balance in the cell wall and as an alternative mediator of endoplasmic reticulum stress in C. glabrata. PMID:27548283

  7. Reduction of sound transmission through fuselage walls by alternate resonance tuning (A.R.T.)

    Science.gov (United States)

    Bliss, Donald B.; Gottwald, James A.

    1989-01-01

    The ability of alternate resonance tuning (ART) to block sound transmission through light-weight flexible paneled walls by controlling the dynamics of the wall panels is considered. Analytical results for sound transmission through an idealized panel wall illustrate the effect of varying system parameters and show that one or more harmonics of the incident sound field can be cancelled by the present method. Experimental results demonstrate that very large transmission losses with reasonable bandwidths can be achieved by a simple ART panel barrier in a duct.

  8. Radio Frequency (RF) Trap for Confinement of Antimatter Plasmas Using Rotating Wall Electric Fields

    Science.gov (United States)

    Sims, William Herbert, III; Pearson, J. Boise

    2004-01-01

    Perturbations associated with a rotating wall electric field enable the confinement of ions for periods approaching weeks. This steady state confinement is a result of a radio frequency manipulation of the ions. Using state-of-the-art techniques it is shown that radio frequency energy can produce useable manipulation of the ion cloud (matter or antimatter) for use in containment experiments. The current research focuses on the improvement of confinement systems capable of containing and transporting antimatter.

  9. Effect of Aspect Ratio, Channel Orientation, Rib Pitch-to-Height Ratio, and Number of Ribbed Walls on Pressure Drop Characteristics in a Rotating Channel with Detached Ribs

    Directory of Open Access Journals (Sweden)

    K. Arun

    2007-01-01

    Full Text Available The present work involves experimental investigation of the effects of aspect ratio, channel orientation angle, rib pitch-to-height ratio (P/e, and number of ribbed walls on friction factor in orthogonally rotating channel with detached ribs. The ribs are separated from the base wall to provide a small region of flow between the base wall and the ribs. Experiments have been conducted at Reynolds number ranging from 10000–17000 with rotation numbers varying from 0–0.38. Pitch-to-rib height ratios (P/e of 5 and 10 at constant rib height-to-hydraulic diameter ratio (e/D of 0.1 and a clearance ratio (C/e of 0.38 are considered. The rib angle of attack with respect to mainstream flow is 90∘. The channel orientation at which the ribbed wall becomes trailing surface (pressure side on which the Coriolis force acts is considered as the 0∘ orientation angle. For one-wall ribbed case, channel is oriented from 0∘ to 180∘ about its axis in steps of 30∘ to change the orientation angle. For two-wall ribbed case, the orientation angle is changed from 0∘ to 90∘ in steps of 30∘. Friction factors for the detached ribbed channels are compared with the corresponding attached ribbed channel. It is found that in one-wall detached ribbed channel, increase in the friction factor ratio with the orientation angle is lower for rectangular channel compared to that of square channel for both the pitch-to-rib height ratios of 5 and 10 at a given Reynolds number and rotation number. Friction factor ratios of two-wall detached ribbed rectangular channel are comparable with corresponding two-wall detached ribbed square channel both under stationary and rotating conditions.

  10. JSC technician checks STS-44 DSO 316 bioreactor and rotating wall vessel hdwr

    Science.gov (United States)

    1991-01-01

    JSC technician Tacey Prewitt checks the progress on a bioreactor experiment in JSC's Life Sciences Laboratory Bldg 37 biotechnology laboratory. Similar hardware is scheduled for testing aboard Atlantis, Orbiter Vehicle (OV) 104, during STS-44. Detailed Supplementary Objective (DSO) 316 Bioreactor/Flow and Particle Trajectory in Microgravity will checkout the rotating wall vessel hardware and hopefully will confirm researchers' theories and calculations about how flow fields work in space. Plastic beads of various sizes rather than cell cultures are being flown in the vessel for the STS-44 test.

  11. Interlocked chiral/polar domain walls and large optical rotation in Ni3TeO6

    Directory of Open Access Journals (Sweden)

    Xueyun Wang

    2015-07-01

    Full Text Available Chirality, i.e., handedness, pervades much of modern science from elementary particles, DNA-based biology to molecular chemistry; however, most of the chirality-relevant materials have been based on complex molecules. Here, we report inorganic single-crystalline Ni3TeO6, forming in a corundum-related R3 structure with both chirality and polarity. These chiral Ni3TeO6 single crystals exhibit a large optical specific rotation (α—1355° dm−1 cm3 g−1. We demonstrate, for the first time, that in Ni3TeO6, chiral and polar domains form an intriguing domain pattern, resembling a radiation warning sign, which stems from interlocked chiral and polar domain walls through lowering of the wall energy.

  12. Use of deep soil mixing as an alternate verticle barrier to slurry walls

    International Nuclear Information System (INIS)

    Miller, A.D.

    1997-01-01

    Slurry walls have become an accepted subsurface remediation technique to contain contaminated zones. However, situations develop where conventional slurry wall excavation techniques are not suitable. The use of conventional containment wall construction methods may involve removal and disposal of contaminated soils, stability concerns and the risk of open excavations. For these reasons, other installation techniques have received further consideration. Deep Soil Mixing (DSM) has emerged as a viable alternative to conventional slurry wall techniques. In situations dictating limited soil removal for contamination or stability concerns, or where space is a limitation, DSM can be used for installation of the barrier. Proper installation of a DSM wall requires sufficient monitoring and sampling to evaluate the continuity, mixing effectiveness, permeability and key into the confining layer. This paper describes a case study where DSM was used to cross major highways to avoid open excavation, and along slopes to reduce stability concerns. The DSM barrier was tied to an existing conventional slurry wall that had been installed in more stable areas without highway traffic

  13. Control of the dielectric microrods rotation in liquid by alternating current electric field

    Science.gov (United States)

    Ren, Yukun; Li, Bin; Jiang, Hongyuan

    2014-05-01

    Microfluidics is a promising system for the manipulation of micro-nano particles and fluids. In this platform, alternating current (AC) electric field is usual an effective tool for the general particles control. However, traditional work paid more attention on the regular spherical particles with no obvious distinction when rotating, resulting in imprecise rotation speed calculation. In essence, non-spherical especially biocompatible particles are not only important for biology application but also significant for obtaining accurate rotating results. Hence, in this paper, SU-8, one of the most biocompatible materials was selected as the manipulation object. AC electric field is employed to rotate SU-8 microrods, in order to obtain a controllable rotation angle for both the accurate experimental results and biosensor applications. Firstly, Clausius-Mossotti(CM) factors frequency spectra with different surface conductance and medium conductivities are presented, thereby the theoretical formula is carried out, including both the torque and rotation velocity expressions of SU-8 microrods. Moreover, simulations for the electric field distribution are developed, indicating the rotating direction. Secondly, the quadrupole electrodes are used to generate rotating electric field, and the electrorotation of SU-8 microrods in different medium is carried out, showing that the particles rotate in the opposite direction of the electric field, meanwhile, the peak frequency increases with the conductivity increases. Finally, the experimental results are discussed and compared with theoretical analysis, and the comparison result shows that they have a good agreement. This work proposes an effective and controllable method to rotate microrods, showing extend application potentials in microelectronics and biosensors.

  14. Intron-mediated alternative splicing of WOOD-ASSOCIATED NAC TRANSCRIPTION FACTOR1B regulates cell wall thickening during fiber development in Populus species.

    Science.gov (United States)

    Zhao, Yunjun; Sun, Jiayan; Xu, Peng; Zhang, Rui; Li, Laigeng

    2014-02-01

    Alternative splicing is an important mechanism involved in regulating the development of multicellular organisms. Although many genes in plants undergo alternative splicing, little is understood of its significance in regulating plant growth and development. In this study, alternative splicing of black cottonwood (Populus trichocarpa) wood-associated NAC domain transcription factor (PtrWNDs), PtrWND1B, is shown to occur exclusively in secondary xylem fiber cells. PtrWND1B is expressed with a normal short-transcript PtrWND1B-s as well as its alternative long-transcript PtrWND1B-l. The intron 2 structure of the PtrWND1B gene was identified as a critical sequence that causes PtrWND1B alternative splicing. Suppression of PtrWND1B expression specifically inhibited fiber cell wall thickening. The two PtrWND1B isoforms play antagonistic roles in regulating cell wall thickening during fiber cell differentiation in Populus spp. PtrWND1B-s overexpression enhanced fiber cell wall thickening, while overexpression of PtrWND1B-l repressed fiber cell wall thickening. Alternative splicing may enable more specific regulation of processes such as fiber cell wall thickening during wood formation.

  15. Stability and control of resistive wall modes in high beta, low rotation DIII-D plasmas

    International Nuclear Information System (INIS)

    Garofalo, A.M.; Jackson, G.L.; Haye, R.J. La; Okabayashi, M.; Reimerdes, H.; Strait, E.J.; Ferron, J.R.; Groebner, R.J.; In, Y.; Lanctot, M.J.; Matsunaga, G.; Navratil, G.A.; Solomon, W.M.; Takahashi, H.; Takechi, M.; Turnbull, A.D.

    2007-01-01

    Recent high-β DIII-D (Luxon J.L. 2002 Nucl. Fusion 42 64) experiments with the new capability of balanced neutral beam injection show that the resistive wall mode (RWM) remains stable when the plasma rotation is lowered to a fraction of a per cent of the Alfven frequency by reducing the injection of angular momentum in discharges with minimized magnetic field errors. Previous DIII-D experiments yielded a high plasma rotation threshold (of order a few per cent of the Alfven frequency) for RWM stabilization when resonant magnetic braking was applied to lower the plasma rotation. We propose that the previously observed rotation threshold can be explained as the entrance into a forbidden band of rotation that results from torque balance including the resonant field amplification by the stable RWM. Resonant braking can also occur naturally in a plasma subject to magnetic instabilities with a zero frequency component, such as edge localized modes. In DIII-D, robust RWM stabilization can be achieved using simultaneous feedback control of the two sets of non-axisymmetric coils. Slow feedback control of the external coils is used for dynamic error field correction; fast feedback control of the internal non-axisymmetric coils provides RWM stabilization during transient periods of low rotation. This method of active control of the n = 1 RWM has opened access to new regimes of high performance in DIII-D. Very high plasma pressure combined with elevated q min for high bootstrap current fraction, and internal transport barriers for high energy confinement, are sustained for almost 2 s, or 10 energy confinement times, suggesting a possible path to high fusion performance, steady-state tokamak scenarios

  16. Intron-Mediated Alternative Splicing of WOOD-ASSOCIATED NAC TRANSCRIPTION FACTOR1B Regulates Cell Wall Thickening during Fiber Development in Populus Species1[W

    Science.gov (United States)

    Zhao, Yunjun; Sun, Jiayan; Xu, Peng; Zhang, Rui; Li, Laigeng

    2014-01-01

    Alternative splicing is an important mechanism involved in regulating the development of multicellular organisms. Although many genes in plants undergo alternative splicing, little is understood of its significance in regulating plant growth and development. In this study, alternative splicing of black cottonwood (Populus trichocarpa) wood-associated NAC domain transcription factor (PtrWNDs), PtrWND1B, is shown to occur exclusively in secondary xylem fiber cells. PtrWND1B is expressed with a normal short-transcript PtrWND1B-s as well as its alternative long-transcript PtrWND1B-l. The intron 2 structure of the PtrWND1B gene was identified as a critical sequence that causes PtrWND1B alternative splicing. Suppression of PtrWND1B expression specifically inhibited fiber cell wall thickening. The two PtrWND1B isoforms play antagonistic roles in regulating cell wall thickening during fiber cell differentiation in Populus spp. PtrWND1B-s overexpression enhanced fiber cell wall thickening, while overexpression of PtrWND1B-l repressed fiber cell wall thickening. Alternative splicing may enable more specific regulation of processes such as fiber cell wall thickening during wood formation. PMID:24394777

  17. Rotational actuator of motor based on carbon nanotubes

    Science.gov (United States)

    Zettl, Alexander K.; Fennimore, Adam M.; Yuzvinsky, Thomas D.

    2008-11-18

    A rotational actuator/motor based on rotation of a carbon nanotube is disclosed. The carbon nanotube is provided with a rotor plate attached to an outer wall, which moves relative to an inner wall of the nanotube. After deposit of a nanotube on a silicon chip substrate, the entire structure may be fabricated by lithography using selected techniques adapted from silicon manufacturing technology. The structures to be fabricated may comprise a multiwall carbon nanotube (MWNT), two in plane stators S1, S2 and a gate stator S3 buried beneath the substrate surface. The MWNT is suspended between two anchor pads and comprises a rotator attached to an outer wall and arranged to move in response to electromagnetic inputs. The substrate is etched away to allow the rotor to freely rotate. Rotation may be either in a reciprocal or fully rotatable manner.

  18. Use of the rice husk as an alternative substrate for growing media on green walls drip irrigation

    Science.gov (United States)

    Andrey Rivas-Sánchez, Yair; Fátima Moreno-Pérez, María; Roldán Cañas, José

    2017-04-01

    In the last years, we have been looking for alternatives to traditional growing mediums for green walls. Commercially available systems for green walls are commonly made with Sphagnum, rock wool or polymers that are unsustainable materials. In the design of the green wall, local components such as agricultural by-products should be considered more often. The objective of this research is to use alternative materials available in Andalusia that are suitable for use as a growing medium in green walls, using organic residues generated by agriculture as in this case the rice husk, compared to conventional and used materials as a growing media in green walls such as coconut fiber and rock wool. The physical-chemical characteristics of the water were analyzed through the collection of excess irrigation water, after passing through the prototypes of green walls, installed in the Rabanales Campus of the University of Córdoba between April and July 2016 and thus observe the feasibility of using rice husk as an alternative material. The 16 mm diameter irrigation pipes are at the top and middle of each module, with 12 adjustable drippers of 4 l / h for each module, 72 drippers in the whole experimental green wall prototype installed at every 15 centimeters of tube. Two different species of plant material (Lampranthus spectabilis) and (Lavandula stoechas), were selected, taking into account the solar exposition of the place of establishment of the prototype of the green wall and the easy acquisition of these plants in the region. Water samples were collected every day twice a day for 10 weeks of the experiment, taking a sample of the surplus runoff water from six green wall prototypes.PH 40 - pH - conductivity - TDS - temperature, CRISON. Differences in pH, electrical conductivity, turbidity and total solids of the treatments were examined by ANOVA with the test of normality and homogeneity of variances. It was observed that the substrates used in the prototypes of the

  19. Computational fluid dynamics modeling of momentum transport in rotating wall perfused bioreactor for cartilage tissue engineering.

    Science.gov (United States)

    Cinbiz, Mahmut N; Tığli, R Seda; Beşkardeş, Işil Gerçek; Gümüşderelioğlu, Menemşe; Colak, Uner

    2010-11-01

    In this study, computational fluid dynamics (CFD) analysis of a rotating-wall perfused-vessel (RWPV) bioreactor is performed to characterize the complex hydrodynamic environment for the simulation of cartilage development in RWPV bioreactor in the presence of tissue-engineered cartilage constructs, i.e., cell-chitosan scaffolds. Shear stress exerted on chitosan scaffolds in bioreactor was calculated for different rotational velocities in the range of 33-38 rpm. According to the calculations, the lateral and lower surfaces were exposed to 0.07926-0.11069 dyne/cm(2) and 0.05974-0.08345 dyne/cm(2), respectively, while upper surfaces of constructs were exposed to 0.09196-0.12847 dyne/cm(2). Results validate adequate hydrodynamic environment for scaffolds in RWPV bioreactor for cartilage tissue development which concludes the suitability of operational conditions of RWPV bioreactor. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. A comparison of the heating effect of magnetic fluid between the alternating and rotating magnetic field

    International Nuclear Information System (INIS)

    Beković, Miloš; Trlep, Mladen; Jesenik, Marko; Hamler, Anton

    2014-01-01

    Magnetic fluids are distinct magnetic materials that have recently been the subject of extensive research precisely because of their unique properties. One of them is the heating effect when exposed to alternating magnetic fields, wherein the objective is to use this property in medicine as an alternative method for the treatment of tumors in the body. In this paper, we focus on two methods of magnetizing magnetic fluids, firstly using the alternating magnetic field (AMF), and secondly with the rotational magnetic field (RMF). The effects of the first are scientifically well-established, whilst the impact of RMF has not as yet been investigated as presented in this article. So far the effects of RMF have only been studied at low frequencies and high amplitudes, or vice versa. This article presents the results of heating at high frequencies and high magnetic field amplitudes, and the results compared with AMF. This paper presents the construction and implementation of a measuring system which is suitable both types of magnetic field. - Highlights: • Development of a new measurement system for the characterization of magnetic fluids. • System enables pulsed magnetic field, or a rotary magnetic field. • Analysis of the conditions to create a rotational magnetic field by means of a double power supply. • Good agreement between the analytical and numerical calculation of magnetic field and measurements. • Increase of the heating power when sample is exposed to rotating field compared to pulsating field

  1. Rotational Fourier tracking of diffusing polygons.

    Science.gov (United States)

    Mayoral, Kenny; Kennair, Terry P; Zhu, Xiaoming; Milazzo, James; Ngo, Kathy; Fryd, Michael M; Mason, Thomas G

    2011-11-01

    We use optical microscopy to measure the rotational Brownian motion of polygonal platelets that are dispersed in a liquid and confined by depletion attractions near a wall. The depletion attraction inhibits out-of-plane translational and rotational Brownian fluctuations, thereby facilitating in-plane imaging and video analysis. By taking fast Fourier transforms (FFTs) of the images and analyzing the angular position of rays in the FFTs, we determine an isolated particle's rotational trajectory, independent of its position. The measured in-plane rotational diffusion coefficients are significantly smaller than estimates for the bulk; this difference is likely due to the close proximity of the particles to the wall arising from the depletion attraction.

  2. From Newton's bucket to rotating polygons

    DEFF Research Database (Denmark)

    Bach, B.; Linnartz, E. C.; Vested, Malene Louise Hovgaard

    2014-01-01

    We present an experimental study of 'polygons' forming on the free surface of a swirling water flow in a partially filled cylindrical container. In our set-up, we rotate the bottom plate and the cylinder wall with separate motors. We thereby vary rotation rate and shear strength independently...... and move from a rigidly rotating 'Newton's bucket' flow to one where bottom and cylinder wall are rotating oppositely and the surface is strongly turbulent but flat on average. Between those two extremes, we find polygonal states for which the rotational symmetry is spontaneously broken. We investigate...... the phase diagram spanned by the two rotational frequencies at a given water filling height and find polygons in a regime, where the two frequencies are sufficiently different and, predominantly, when they have opposite signs. In addition to the extension of the family of polygons found with the stationary...

  3. Analysis of a Floodplain I-Wall Embedded in Horizontally Stratified Soil Layers During Flood Events Using Corps I-Wall Software Version 1.0

    Science.gov (United States)

    2016-07-01

    100, 300, 500 and 1,000 simulations. ........................... 255 Figure A1. Cantilever retaining wall . (a) Two layered soil site. (b...of flood elevation. In a safety or risk assessment of I- Walls , the rotational limit state or probability of rotational failure of the I- Wall about a...for the net loading is computed about the lower of the RHS or LHS ground surfaces for level ground, for a retaining wall design with differential

  4. Development of full scale testing of an alternate foundation system for post and panel retaining walls.

    Science.gov (United States)

    2009-03-01

    The alternate post system offers benefits such as ease of construction, reduced construction time, and : lower wall costs. While this system seems feasible, there are concerns regarding its performance, in : particular the amount of bending in the po...

  5. Behavior of a heavy cylinder in a horizontal cylindrical liquid-filled cavity at modulated rotation

    International Nuclear Information System (INIS)

    Kozlov, Nikolai V; Vlasova, Olga A

    2016-01-01

    The behavior of a heavy cylindrical solid in a horizontal cylindrical cavity is experimentally investigated. The cavity is filled with a viscous liquid and rotates. Two rotation regimes are considered. The first one is steady rotation. A number of body motion regimes are found depending on the cavity rotation speed. The second regime is a modulated rotation, in which the rotation speed is varying periodically. It can be presented as a sum of steady rotation and librations. On the whole, three different cases of the body repulsion from the cavity wall are observed. In the first case, the repulsion occurs when the body slides over a rotating cavity wall. In the second case, the body being in the centrifuged state—when it rotates with the fluid—detaches from the cavity wall under the action of gravity. In the third case, at librations, the wall performs oscillations and the body is repulsed from the wall due to the nonlinear viscous interaction with the fluid. (paper)

  6. Reynolds-Stress and Triple-Product Models Applied to a Flow with Rotation and Curvature

    Science.gov (United States)

    Olsen, Michael E.

    2016-01-01

    Turbulence models, with increasing complexity, up to triple product terms, are applied to the flow in a rotating pipe. The rotating pipe is a challenging case for turbulence models as it contains significant rotational and curvature effects. The flow field starts with the classic fully developed pipe flow, with a stationary pipe wall. This well defined condition is then subjected to a section of pipe with a rotating wall. The rotating wall introduces a second velocity scale, and creates Reynolds shear stresses in the radial-circumferential and circumferential-axial planes. Furthermore, the wall rotation introduces a flow stabilization, and actually reduces the turbulent kinetic energy as the flow moves along the rotating wall section. It is shown in the present work that the Reynolds stress models are capable of predicting significant reduction in the turbulent kinetic energy, but triple product improves the predictions of the centerline turbulent kinetic energy, which is governed by convection, dissipation and transport terms, as the production terms vanish on the pipe axis.

  7. Kinetic wall from Israel

    Energy Technology Data Exchange (ETDEWEB)

    Godolphin, D.

    1985-05-01

    An unusual solar mass wall is described. At the turn of a handle it can change from a solar energy collector to a heat-blocker. An appropriate name for it might be the rotating prism wall. An example of the moving wall is at work in an adobe test home in Sede Boqer. Behind a large south-facing window stand four large adobe columns that are triangular in plan. One face of each of them is painted black to absorb sunlight, a second is covered with panels of polystyrene insulation, and a third is painted to match the room decor. These columns can rotate. On winter nights, the insulated side faces the glass, keeping heat losses down. The same scheme works in summer to keep heat out of the house. Small windows provide ventilation.

  8. Radio Frequency Trap for Containment of Plasmas in Antimatter Propulsion Systems Using Rotating Wall Electric Fields

    Science.gov (United States)

    Sims, William Herbert, III (Inventor); Martin, James Joseph (Inventor); Lewis, Raymond A. (Inventor)

    2003-01-01

    A containment apparatus for containing a cloud of charged particles comprises a cylindrical vacuum chamber having a longitudinal axis. Within the vacuum chamber is a containment region. A magnetic field is aligned with the longitudinal axis of the vacuum chamber. The magnetic field is time invariant and uniform in strength over the containment region. An electric field is also aligned with the longitudinal axis of the vacuum chamber and the magnetic field. The electric field is time invariant, and forms a potential well over the containment region. One or more means are disposed around the cloud of particles for inducing a rotating electric field internal to the vacuum chamber. The rotating electric field imparts energy to the charged particles within the containment region and compress the cloud of particles. The means disposed around the outer surface of the vacuum chamber for inducing a rotating electric field are four or more segments forming a segmented ring, the segments conforming to the outer surface of the vacuum chamber. Each of the segments is energized by a separate alternating voltage. The sum of the voltages imposed on each segment establishes the rotating field. When four segments form a ring, the rotating field is obtained by a signal generator applying a sinusoidal signal phase delayed by 90,180 and 270 degrees in sequence to the four segments.

  9. Impact of alternative harvesting technologies on thinning entry and optimal rotation age for eastern hardwoods

    Science.gov (United States)

    Chris B. LeDoux

    2007-01-01

    A complete system simulation model is used to integrate alternative logging technologies, stand data, market prices, transportation costs, and economic concerns in a longterm continuous manner to evaluate thinning entry timing and optimal rotation age. Forest Inventory and Analysis (FIA) stand data for the oak/hickory forest type and time and motion study data for 70,...

  10. Turbulent heat transfer studies in annulus with inner cylinder rotation

    International Nuclear Information System (INIS)

    Kuzay, T.M.; Scott, C.J.

    1977-01-01

    Experimental investigations of turbulent heat transfer are made in a large-gap annulus with both rotating and nonrotating inner cylinder. The vertical annular channel has an electrically heated outer wall; the inner wall i thermally and electrically insulated. The axial air flow is allowed to develop before rotation and heating are imparted. The resulting temperature fields are investigated using thermocouple probes located near the channel exit. The wall heat flux, wall axial temperature development, and radial temperature profiles are measured. For each axial Reynolds number, three heat flux rates are used. Excellent correlation is established between rotational and nonrotational Nusselt number. The proper correlation parameter is a physical quantity characterizing the flow helix. This parameter is the inverse of the ratio of axial travel of the flow helix in terms of hydraulic diameter, per half revolution of the spinning wall

  11. Active and passive kink mode studies in a tokamak with a movable ferromagnetic wall

    Energy Technology Data Exchange (ETDEWEB)

    Levesque, J. P.; Hughes, P. E.; Bialek, J.; Byrne, P. J.; Mauel, M. E.; Navratil, G. A.; Peng, Q.; Rhodes, D. J.; Stoafer, C. C. [Department of Applied Physics and Applied Mathematics, Columbia University, 500 W. 120th Street, New York, New York 10027 (United States)

    2015-05-15

    High-resolution active and passive kink mode studies are conducted in a tokamak with an adjustable ferromagnetic wall near the plasma surface. Ferritic tiles made from 5.6 mm thick Hiperco{sup ®} 50 alloy have been mounted on the plasma-facing side of half of the in-vessel movable wall segments in the High Beta Tokamak-Extended Pulse device [D. A. Maurer et al., Plasma Phys. Controlled Fusion 53, 074016 (2011)] in order to explore ferritic resistive wall mode stability. Low-activation ferritic steels are a candidate for structural components of a fusion reactor, and these experiments examine MHD stability of plasmas with nearby ferromagnetic material. Plasma-wall separation for alternating ferritic and non-ferritic wall segments is adjusted between discharges without opening the vacuum vessel. Amplification of applied resonant magnetic perturbations and plasma disruptivity are observed to increase when the ferromagnetic wall is close to plasma surface instead of the standard stainless steel wall. Rapidly rotating m/n=3/1 external kink modes have higher growth rates with the nearby ferritic wall. Feedback suppression of kinks is still as effective as before the installation of ferritic material in vessel, in spite of increased mode growth rates.

  12. Linear instability and nonlinear motion of rotating plasma

    International Nuclear Information System (INIS)

    Liu, J.

    1985-01-01

    Two coupled nonlinear equations describing the flute dynamics of the magnetically confined low-β collisionless rotating plasma are derived. The linear instability and nonlinear dynamics of the rotating column are analyzed theoretically. In the linear stability analysis, a new sufficient condition of stability is obtained. From the exact solution of eigenvalue equation for Gaussian density profile and uniform rotation of the plasma, the stability of the system strongly depends on the direction of plasma rotation, FLR effect and the location of the conducting wall. An analytic expression showing the finite wall effect on different normal modes is obtained and it explains the different behavior of (1,0) normal mode from other modes. The sheared rotation driven instability is investigated by using three model equilibrium profiles, and the analytic expressions of eigenvalues which includes the wall effect are obtained. The analogy between shear rotation driven instability and the instability driven by sheared plane parallel flow in the inviscid fluid is analyzed. Applying the linear analysis to the central cell of tandem mirror system, the trapped particle instability with only passing electronics is analyzed. For uniform rotation and Gaussian density profile, an analytic expression that determines the stability boundary is found. The nonlinear analysis shows that the nonlinear equations have a solitary vortex solution which is very similar to the vortex solution of nonlinear Rossby wave equation

  13. Short-rotation forestry as an alternative land use in Hawaii

    International Nuclear Information System (INIS)

    Phillips, V.D.; Wei Liu; Merriam, R.A.

    1995-01-01

    The traditional mainstays of Hawaii's economy: sugarcane and pineapple crops, have declined such that as much as 80,000 hectares of agricultural land are now available for alternative land uses. Concurrently, imports of fossil fuels continue to accelerate and now provide over 90% of the total energy supply at a cost exceeding 1 billion dollars annually exported from the local economy. The feasibility of short-rotation forestry on these former sugarcane and pineapple plantation lands to produce a variety of wood products, including biofuels, is being evaluated using a species- and site-specific empirical model to predict yields of Eucalyptus saligna, a system model to estimate delivered costs of wood chips to a bioconversion facility, and a geographic information system to extend the analysis to areas where no field trials exist and to present results in map form. The island of Hawaii is showcased as an application of the methodology. Modelling results are presented for using tropical hardwoods as dedicated feedstocks from biomass energy plantations to produce methanol, ethanol and electricity. A hypothetical, integrated, high-value hardwood, veneer, utility lumber and wood-chip operation is featured in contrast to the biomass energy plantation scenario. Short-rotation forestry may hold some promise for the greening of Hawaii's energy system and even greater promise for the industrial production of value-added wood products for the benefit of the state's citizens and visitors. The methodology is readily transferable to other regions of the United States and the rest of the world. (author)

  14. Short-rotation forestry as an alternative land use in Hawaii

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, V.D.; Wei Liu [Hawaii Univ., Honolulu, HI (United States). Coll. of Tropical Agriculture and Human Resources; Bain, R.L. [National Renewable Energy Lab., Golden, CO (United States); Merriam, R.A.

    1995-12-31

    The traditional mainstays of Hawaii`s economy: sugarcane and pineapple crops, have declined such that as much as 80,000 hectares of agricultural land are now available for alternative land uses. Concurrently, imports of fossil fuels continue to accelerate and now provide over 90% of the total energy supply at a cost exceeding 1 billion dollars annually exported from the local economy. The feasibility of short-rotation forestry on these former sugarcane and pineapple plantation lands to produce a variety of wood products, including biofuels, is being evaluated using a species- and site-specific empirical model to predict yields of Eucalyptus saligna, a system model to estimate delivered costs of wood chips to a bioconversion facility, and a geographic information system to extend the analysis to areas where no field trials exist and to present results in map form. The island of Hawaii is showcased as an application of the methodology. Modelling results are presented for using tropical hardwoods as dedicated feedstocks from biomass energy plantations to produce methanol, ethanol and electricity. A hypothetical, integrated, high-value hardwood, veneer, utility lumber and wood-chip operation is featured in contrast to the biomass energy plantation scenario. Short-rotation forestry may hold some promise for the greening of Hawaii`s energy system and even greater promise for the industrial production of value-added wood products for the benefit of the state`s citizens and visitors. The methodology is readily transferable to other regions of the United States and the rest of the world. (author)

  15. A new alternative in vertical barrier wall construction

    International Nuclear Information System (INIS)

    Rawl, G.F.

    1997-01-01

    A new proprietary vertical barrier wall system has been developed to revolutionize the construction process by eliminating many of the concerns of conventional installation method's with respect to performance, installation constraints and costs. Vertical barrier walls have been used in the environmental and construction industries for a variety of purposes, usually for cut-off or containment. The typical scenario involves a groundwater contamination problem, in which a vertical barrier wall is utilized to contain or confine the spread of contaminants below the ground surface. Conventional construction techniques have been adequate in many applications, but often fall short of their intended purposes due to physical constraints. In many instances, the economics of these conventional methods have limited the utilization of physical barrier walls. Polywall, the trade name for this new barrier wall technology, was subsequently developed to meet these needs and offer a number of distinct advantages in a variety of scenarios by maximizing confinement and minimizing installation costs. Polywall is constructed from chemically resistant high density polyethylene (HDPE) plastic. It has proven in a half-dozen projects to date to be the most cost-effective and technically sound approach to many containment situations. This paper will cover the development of the technology and will provide a brief synopsis of several installations

  16. Rotation Effect on Jet Impingement Heat Transfer in Smooth Rectangular Channels with Film Coolant Extraction

    Directory of Open Access Journals (Sweden)

    James A. Parsons

    2001-01-01

    Full Text Available The effect of channel rotation on jet impingement cooling by arrays of circular jets in twin channels was studied. Impinging jet flows were in the direction of rotation in one channel and opposite to the direction of rotation in the other channel. The jets impinged normally on the smooth, heated target wall in each channel. The spent air exited the channels through extraction holes in each target wall, which eliminates cross flow on other jets. Jet rotation numbers and jet Reynolds numbers varied from 0.0 to 0.0028 and 5000 to 10,000, respectively. For the target walls with jet flow in the direction of rotation (or opposite to the direction of rotation, as rotation number increases heat transfer decreases up to 25% (or 15% as compared to corresponding results for non-rotating conditions. This is due to the changes in flow distribution and rotation induced Coriolis and centrifugal forces.

  17. Formation of three-dimensional cell/polymer constructs for bone tissue engineering in a spinner flask and a rotating wall vessel bioreactor

    Science.gov (United States)

    Sikavitsas, Vassilios I.; Bancroft, Gregory N.; Mikos, Antonios G.; McIntire, L. V. (Principal Investigator)

    2002-01-01

    The aim of this study is to investigate the effect of the cell culture conditions of three-dimensional polymer scaffolds seeded with rat marrow stromal cells (MSCs) cultured in different bioreactors concerning the ability of these cells to proliferate, differentiate towards the osteoblastic lineage, and generate mineralized extracellular matrix. MSCs harvested from male Sprague-Dawley rats were culture expanded, seeded on three-dimensional porous 75:25 poly(D,L-lactic-co-glycolic acid) biodegradable scaffolds, and cultured for 21 days under static conditions or in two model bioreactors (a spinner flask and a rotating wall vessel) that enhance mixing of the media and provide better nutrient transport to the seeded cells. The spinner flask culture demonstrated a 60% enhanced proliferation at the end of the first week when compared to static culture. On day 14, all cell/polymer constructs exhibited their maximum alkaline phosphatase activity (AP). Cell/polymer constructs cultured in the spinner flask had 2.4 times higher AP activity than constructs cultured under static conditions on day 14. The total osteocalcin (OC) secretion in the spinner flask culture was 3.5 times higher than the static culture, with a peak OC secretion occurring on day 18. No considerable AP activity and OC secretion were detected in the rotating wall vessel culture throughout the 21-day culture period. The spinner flask culture had the highest calcium content at day 14. On day 21, the calcium deposition in the spinner flask culture was 6.6 times higher than the static cultured constructs and over 30 times higher than the rotating wall vessel culture. Histological sections showed concentration of cells and mineralization at the exterior of the foams at day 21. This phenomenon may arise from the potential existence of nutrient concentration gradients at the interior of the scaffolds. The better mixing provided in the spinner flask, external to the outer surface of the scaffolds, may explain the

  18. Rotating liquid blanket for a toroidal fusion reator

    International Nuclear Information System (INIS)

    Moir, R.W.

    1987-01-01

    A novel blanket concept is presented for toroidal geometry in which many of the limitations imposed by a first wall are avoided by not having a first wall in the usual sense. The blanket consists of a rapidly rotating, low-vapor-pressure liquid that has a sharp boundary with the vacuum region. Nozzles inject ja continuous layer of cool liquid on the inner surface. The noncentricity of the plasma is maintained so that the plasma scrape-off region intersects the rotating liqid in a localized region. This noncentricity allows sufficient space so that the scrape-off plasma layer will not bombard the nozzles, whch penetrate through the rotating liquid. This liquid ''first wall'' is bombarded by the plasma, resulting in heat deposition, sputtering, and evaporation during the short time before the exposed liquid is covered by fresh, cool liquid from the nozzles. The advantages of this reactor concept appear to be very high wall loadings (speculated to be over 10 MW/m 2 ) and long component lifetime, both crucial economic factors. The nozzles are designed for easy replacement. The reactor's disatvantage is its enormous potential for plasma contamination by impurities. (orig.)

  19. Supertube domain walls and elimination of closed timelike curves in string theory

    International Nuclear Information System (INIS)

    Drukker, Nadav

    2004-01-01

    We show that some novel physics of supertubes removes closed timelike curves from many supersymmetric spaces which naively suffer from this problem. The main claim is that supertubes naturally form domain walls, so while analytical continuation of the metric would lead to closed timelike curves, across the domain wall the metric is nondifferentiable, and the closed timelike curves are eliminated. In the examples we study, the metric inside the domain wall is always of the Goedel type, while outside the shell it looks like a localized rotating object, often a rotating black hole. Thus this mechanism prevents the appearance of closed timelike curves behind the horizons of certain rotating black holes

  20. Magnetization reversal in ferromagnetic spirals via domain wall motion

    Science.gov (United States)

    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.

  1. Active particle control experiments and critical particle flux discriminating between the wall pumping and fuelling in the compact plasma wall interaction device CPD spherical tokamak

    International Nuclear Information System (INIS)

    Zushi, H.; Sakamoto, M.; Yoshinaga, T.; Higashizono, Y.; Hanada, K.; Yoshida, N.; Tokunaga, K.; Kawasaki, S.; Sato, K. N.; Nakamura, K.; Idei, H.; Hirooka, Y.; Bhattacharyay, R.; Okamoto, K.; Miyazaki, T.; Honma, H.; Nakashima, Y.; Nishino, N.; Kado, S.; Shikama, T.

    2009-01-01

    Two approaches associated with wall recycling have been performed in a small spherical tokamak device CPD (compact plasma wall interaction experimental device), that is, (1) demonstration of active particle recycling control, namely, 'active wall pumping' using a rotating poloidal limiter whose surface is continuously gettered by lithium and (2) a basic study of the key parameters which discriminates between 'wall pumping and fuelling'. For the former, active control of 'wall pumping' has been demonstrated during 50 kW RF current drive discharges whose pulse length is typically ∼300 ms. Although the rotating limiter is located at the outer board, as soon as the rotating drum is gettered with lithium, hydrogen recycling measured with H α spectroscopy decreases by about a factor of 3 not only near the limiter but also in the centre stack region. Also, the oxygen impurity level measured with O II spectroscopy is reduced by about a factor of 3. As a consequence of the reduced recycling and impurity level, RF driven current has nearly doubled at the same vertical magnetic field. For the latter, global plasma wall interaction with plasma facing components in the vessel is studied in a simple torus produced by electron cyclotron waves with I p -4 to ∼0.1 x 10 -4 Torr during the experimental campaign (∼3000 shots). In the wall pumping pressure range the wall pumping fraction is reduced with increasing surface temperature up to 150 deg. C.

  2. Cartan frames for heart wall fiber motion

    NARCIS (Netherlands)

    Samari, Babak; Aumentado-Armstrong, Tristan; Strijkers, Gustav J.; Froeling, Martijn; Siddiqi, Kaleem

    2017-01-01

    Current understanding of heart wall fiber geometry is based on ex vivo static data obtained through diffusion imaging or histology. Thus, little is known about the manner in which fibers rotate as the heart beats. Yet, the geometric organization of moving fibers in the heart wall is key to its

  3. Halo current and resistive wall simulations of ITER

    International Nuclear Information System (INIS)

    Strauss, H.R.; Zheng Linjin; Kotschenreuther, M.; Park, W.; Jardin, S.; Breslau, J.; Pletzer, A.; Paccagnella, R.; Sugiyama, L.; Chu, M.; Chance, M.; Turnbull, A.

    2005-01-01

    A number of ITER relevant problems in resistive MHD concern the effects of a resistive wall: vertical displacement events (VDE), halo currents caused by disruptions, and resistive wall modes. Simulations of these events have been carried out using the M3D code. We have verified the growth rate scaling of VDEs, which is proportional to the wall resistivity. Simulations have been done of disruptions caused by large inversion radius internal kink modes, as well as by nonlinear growth of resistive wall modes. Halo current flowing during the disruption has asymmetries with toroidal peaking factor up to about 3. VDEs have larger growth rates during disruption simulations, which may account for the loss of vertical feedback control during disruptions in experiments. Further simulations have been made of disruptions caused by resistive wall modes in ITER equilibria. For these modes the toroidal peaking factor is close to 1. Resistive wall modes in ITER and reactors have also been investigated utilizing the newly developed AEGIS (Adaptive EiGenfunction Independent Solution) linear full MHD code, for realistically shaped, fully toroidal equilibria. The AEGIS code uses an adaptive mesh in the radial direction which allows thin inertial layers to be accurately resolved, such as those responsible for the stabilization of resistive wall modes (RWM) by plasma rotation. Stabilization of resistive wall modes by rotation and wall thickness effects are examined. (author)

  4. Dynamics of molecular rotors confined in two dimensions: transition from a 2D rotational glass to a 2D rotational fluid in a periodic mesoporous organosilica.

    Science.gov (United States)

    Vogelsberg, Cortnie S; Bracco, Silvia; Beretta, Mario; Comotti, Angiolina; Sozzani, Piero; Garcia-Garibay, Miguel A

    2012-02-09

    The motional behavior of p-phenylene-d(4) rotators confined within the 2D layers of a hierarchically ordered periodic mesoporous p-divinylbenzenesilica has been elucidated to evaluate the effects of reduced dimensionality on the engineered dynamics of artificial molecular machines. The hybrid mesoporous material, characterized by a honeycomb lattice structure, has arrays of alternating p-divinylbenzene rotors and siloxane layers forming the molecularly ordered walls of the mesoscopic channels. The p-divinylbenzene rotors are strongly anchored between two adjacent siloxane sheets, so that the p-phenylene rotators are unable to experience translational diffusion and are allowed to rotate about only one fixed axis. Variable-temperature (2)H NMR experiments revealed that the p-phenylene rotators undergo an exchange process between sites related by 180° and a non-Arrhenius temperature dependence of the dynamics, with reorientational rates ranging from 10(3) to 10(8) Hz between 215 to 305 K. The regime of motion changes rapidly at about 280 K indicating the occurrence of a dynamical transition. The transition was also recognized by a steep change in the heat capacity at constant pressure. As a result of the robust lamellar architecture comprising the pore walls, the orientational dynamic disorder related to the phase transition is only realized in two dimensions within the layers, that is in the plane perpendicular to the channel axis. Thus, the aligned rotors that form the organic layers exhibit unique anisotropic dynamical properties as a result of the architecture's reduced dimensionality. The dynamical disorder restricted to two dimensions constitutes a highly mobile fluidlike rotational phase at room temperature, which upon cooling undergoes a transition to a more rigid glasslike phase. Activation energies of 5.9 and 9.5 kcal/mol respectively have been measured for the two dynamical regimes of rotation. Collectively, our investigation has led to the discovery of an

  5. Vibration due to non-circularity of a rotating ring having discrete radial supports - With application to thin-walled rotor/magnetic bearing systems

    Science.gov (United States)

    Fakkaew, Wichaphon; Cole, Matthew O. T.

    2018-06-01

    This paper investigates the vibration arising in a thin-walled cylindrical rotor subject to small non-circularity and coupled to discrete space-fixed radial bearing supports. A Fourier series description of rotor non-circularity is incorporated within a mathematical model for vibration of a rotating annulus. This model predicts the multi-harmonic excitation of the rotor wall due to bearing interactions. For each non-circularity harmonic there is a set of distinct critical speeds at which resonance can potentially arise due to flexural mode excitation within the rotor wall. It is shown that whether each potential resonance occurs depends on the multiplicity and symmetry of the bearing supports. Also, a sufficient number of evenly spaced identical supports will eliminate low order resonances. The considered problem is pertinent to the design and operation of thin-walled rotors with active magnetic bearing (AMB) supports, for which small clearances exist between the rotor and bearing and so vibration excitation must be limited to avoid contacts. With this motivation, the mathematical model is further developed for the case of a distributed array of electromagnetic actuators controlled by feedback of measured rotor wall displacements. A case study involving an experimental system with short cylindrical rotor and a single radial AMB support is presented. The results show that flexural mode resonance is largely avoided for the considered design topology. Moreover, numerical predictions based on measured non-circularity show good agreement with measurements of rotor wall vibration, thereby confirming the validity and utility of the theoretical model.

  6. Rotational effects on turbine blade cooling

    Energy Technology Data Exchange (ETDEWEB)

    Govatzidakis, G.J.; Guenette, G.R.; Kerrebrock, J.L. [Massachusetts Institute of Technology, Cambridge, MA (United States)

    1995-10-01

    An experimental investigation of the influence of rotation on the heat transfer in a smooth, rectangular passage rotating in the orthogonal mode is presented. The passage simulates one of the cooling channels found in gas turbine blades. A constant heat flux is imposed on the model with either inward or outward flow. The effects of rotation and buoyancy on the Nusselt number were quantified by systematically varying the Rotation number, Density Ratio, Reynolds number, and Buoyancy parameter. The experiment utilizes a high resolution infrared temperature measurement technique in order to measure the wall temperature distribution. The experimental results show that the rotational effects on the Nusselt number are significant and proper turbine blade design must take into account the effects of rotation, buoyancy, and flow direction. The behavior of the Nusselt number distribution depends strongly on the particular side, axial position, flow direction, and the specific range of the scaling parameters. The results show a strong coupling between buoyancy and Corollas effects throughout the passage. For outward flow, the trailing side Nusselt numbers increase with Rotation number relative to stationary values. On the leading side, the Nusselt numbers tended to decrease with rotation near the inlet and subsequently increased farther downstream in the passage. The Nusselt numbers on the side walls generally increased with rotation. For inward flow, the Nusselt numbers generally improved relative to stationary results, but increases in the Nusselt number were relatively smaller than in the case of outward flow. For outward and inward flows, increasing the density ratio generally tended to decrease Nusselt numbers on the leading and trailing sides, but the exact behavior and magnitude depended on the local axial position and specific range of Buoyancy parameters.

  7. On Job Rotation

    OpenAIRE

    Metin M. Cosgel; Thomas J. Miceli

    1998-01-01

    A fundamental principle of economics with which Adam Smith begins The Wealth of Nations is the division of labor. Some firms, however, have been pursuing a practice called job rotation, which assigns each worker not to a single and specific task but to a set of several tasks among which he or she rotates with some frequency. We examine the practice of job rotation as a serious alternative to specialization, with three objectives. The first is to consider current and historical examples of job...

  8. A stable high-speed rotational transmission system based on nanotubes

    International Nuclear Information System (INIS)

    Cai, Kun; Yin, Hang; Wei, Ning; Chen, Zhen; Shi, Jiao

    2015-01-01

    A stable rotational transmission system is designed with a single-walled carbon nanotube (SWCNT)-based motor and double-walled carbon nanotubes (DWCNTs)-based bearing. The system response is investigated using molecular dynamics (MD) simulation. It is found that the rotating motor can actuate the rotation of the inner tube in bearing because of the attraction between the two adjacent coaxial ends of motor and rotor (the inner tube in bearing). To have a stable nanostructure, each carbon atom on the adjacent ends of motor and rotor is bonded with a hydrogen atom. To obtain a stable high-speed rotational transmission system, both an armchair and a zigzag model are used in MD simulation. In each model, the motor with different diameters and rotational speeds is employed to examine the rotational transmission of corresponding DWCNTs. It is demonstrated that the long range van der Waals interaction between the adjacent ends of motor and rotor leads to a stable configuration of the adjacent ends, and further leads to a stable rotation of rotor when driven by a high-speed motor. As compared with the armchair model, the rotor in the zigzag model could reach a stable rotation mode much easier

  9. Spontaneous Rotational Inversion in Phycomyces

    KAUST Repository

    Goriely, Alain

    2011-03-01

    The filamentary fungus Phycomyces blakesleeanus undergoes a series of remarkable transitions during aerial growth. During what is known as the stagea IV growth phase, the fungus extends while rotating in a counterclockwise manner when viewed from above (stagea IVa) and then, while continuing to grow, spontaneously reverses to a clockwise rotation (stagea IVb). This phase lasts for 24-48Ah and is sometimes followed by yet another reversal (stageAIVc) before the overall growth ends. Here, we propose a continuum mechanical model of this entire process using nonlinear, anisotropic, elasticity and show how helical anisotropy associated with the cell wall structure can induce spontaneous rotation and, under appropriate circumstances, the observed reversal of rotational handedness. © 2011 American Physical Society.

  10. Wall Shear Stress, Wall Pressure and Near Wall Velocity Field Relationships in a Whirling Annular Seal

    Science.gov (United States)

    Morrison, Gerald L.; Winslow, Robert B.; Thames, H. Davis, III

    1996-01-01

    The mean and phase averaged pressure and wall shear stress distributions were measured on the stator wall of a 50% eccentric annular seal which was whirling in a circular orbit at the same speed as the shaft rotation. The shear stresses were measured using flush mounted hot-film probes. Four different operating conditions were considered consisting of Reynolds numbers of 12,000 and 24,000 and Taylor numbers of 3,300 and 6,600. At each of the operating conditions the axial distribution (from Z/L = -0.2 to 1.2) of the mean pressure, shear stress magnitude, and shear stress direction on the stator wall were measured. Also measured were the phase averaged pressure and shear stress. These data were combined to calculate the force distributions along the seal length. Integration of the force distributions result in the net forces and moments generated by the pressure and shear stresses. The flow field inside the seal operating at a Reynolds number of 24,000 and a Taylor number of 6,600 has been measured using a 3-D laser Doppler anemometer system. Phase averaged wall pressure and wall shear stress are presented along with phase averaged mean velocity and turbulence kinetic energy distributions located 0.16c from the stator wall where c is the seal clearance. The relationships between the velocity, turbulence, wall pressure and wall shear stress are very complex and do not follow simple bulk flow predictions.

  11. Treatment Alternative for Irreparable Rotator Cuff Ruptures ...

    African Journals Online (AJOL)

    2016-09-03

    Sep 3, 2016 ... and such ruptures also lead to a pseudo-paralysis.[1,2]. Pain during daily ... 2) repairable rotator cuff rupture, as determined on MRI and during arthroscopy ..... functioning and lead to cosmetic deformities.[4]. Arthroplasty is a ...

  12. Hybrid NOTES transvaginal intraperitoneal onlay mesh in abdominal wall hernias: an alternative to traditional laparoscopic procedures.

    Science.gov (United States)

    Descloux, Alexandre; Pohle, Sebastian; Nocito, Antonio; Keerl, Andreas

    2015-12-01

    Abdominal wall hernias are increasingly treated by laparoscopic placement of an intraperitoneal onlay mesh (IPOM). We present an alternative technique for women: the laparoscopic-assisted transvaginal IPOM. Before surgery, all patients underwent a gynecological examination. The patients agreed to IPOM repair via a transvaginal approach, and written informed consent for surgery was obtained. Pneumoperitoneum was established with a Veress needle at the umbilicus. This access was subsequently dilated to 5 mm (VersaStep), and a 5-mm laparoscope was inserted. Under laparoscopic view, the transvaginal trocars (12-mm VersaStep and 5-mm flexible accesses) were safely inserted after lifting the uterus with a uterus manipulator. After preparation of the falciform ligament, the ligamentum teres and the preperitoneal fat, a lightweight composite mesh was introduced through the transvaginal access and fixed with absorbable tacks using the double-crown technique. From September 2011 to December 2012, we performed six laparoscopic-assisted transvaginal IPOM procedures (one epigastric, three umbilical, two combined epigastric and umbilical hernias; all were primary hernias). In the initial phase, only patients with small or medium primary abdominal wall hernia were selected (max. 3 cm diameter). Median hospital stay was 3 days (range 2-6 days). One minor complication occurred perioperatively (second-degree skin burn to the labia majora). At 1-year follow-up, we identified one recurrence in a high-risk patient with a body mass index higher than 35 kg/m(2). No infection and no mortality were observed. Although no final conclusion can be made regarding the presumed non-inferiority of this technique in terms of recurrence and mesh infection compared with traditional laparoscopic IPOM, laparoscopic-assisted transvaginal IPOM is a feasible alternative to treat abdominal wall hernias.

  13. Permeable treatment wall design and cost analysis

    International Nuclear Information System (INIS)

    Manz, C.; Quinn, K.

    1997-01-01

    A permeable treatment wall utilizing the funnel and gate technology has been chosen as the final remedial solution for one industrial site, and is being considered at other contaminated sites, such as a closed municipal landfill. Reactive iron gates will be utilized for treatment of chlorinated VOCs identified in the groundwater. Alternatives for the final remedial solution at each site were evaluated to achieve site closure in the most cost effective manner. This paper presents the remedial alternatives and cost analyses for each site. Several options are available at most sites for the design of a permeable treatment wall. Our analysis demonstrates that the major cost factor's for this technology are the design concept, length, thickness, location and construction methods for the reactive wall. Minimizing the amount of iron by placement in the most effective area and construction by the lowest cost method is critical to achieving a low cost alternative. These costs dictate the design of a permeable treatment wall, including selection of a variety of alternatives (e.g., a continuous wall versus a funnel and gate system, fully penetrating gates versus partially penetrating gates, etc.). Selection of the appropriate construction methods and materials for the site can reduce the overall cost of the wall

  14. Compression of positron clouds using rotating wall electric fields

    International Nuclear Information System (INIS)

    Werf, Dirk Peter van der; Isaac, Christopher Aled; Baker, Christopher John; Mortensen, Timothy; Charlton, Michael

    2012-01-01

    An asymmetric dipolar rotating electric field can be used to compress a trapped cloud of positrons when applied with a frequency close that of their axial bounce, and in the presence of a low pressure molecular gas to provide cooling. Measurements of the compression rate and associated parameters are presented and compared with results of a theory we have developed. The latter treats positron behaviour in a perfect Penning trap potential, in the presence of the rotating field, with the cooling modelled in the Stokes viscous drag approximation. Good agreement between the theory and experiment has been found, which has allowed us to identify the phenomenon as a new form of sideband cooling.

  15. In-situ Raman microprobe studies of plant cell walls: macromolecular organization and compositional variability in the secondary wall of Picea mariana (Mill.) B.S.P.

    Science.gov (United States)

    U.P. Agarwal; R.H. Atalla

    1986-01-01

    Native-state organization and distribution of cell-wall components in the secondary wall of woody tissue from P. mariana (Black Spruce) have been investigated using polarized Raman microspectroscopy. Evidence for orientation is detected through Raman intensity variations resulting from rotations of the exciting electric vector with respect to cell-wall geometry....

  16. Gender differences in passive knee biomechanical properties in tibial rotation.

    Science.gov (United States)

    Park, Hyung-Soon; Wilson, Nicole A; Zhang, Li-Qun

    2008-07-01

    The anterior cruciate ligament (ACL) is the most commonly injured knee ligament with the highest incidence of injury in female athletes who participate in pivoting sports. Noncontact ACL injuries commonly occur with both internal and external tibial rotation. ACL impingement against the lateral wall of the intercondylar notch during tibial external rotation and abduction has been proposed as an injury mechanism, but few studies have evaluated in vivo gender-specific differences in laxity and stiffness in external and internal tibial rotations. The purpose of this study was to evaluate these differences. The knees of 10 male and 10 female healthy subjects were rotated between internal and external tibial rotation with the knee at 60 degrees of flexion. Joint laxity, stiffness, and energy loss were compared between male and female subjects. Women had higher laxity (p = 0.01), lower stiffness (p = 0.038), and higher energy loss (p = 0.008) in external tibial rotation than did men. The results suggest that women may be at greater risk of ACL injury resulting from impingement against the lateral wall of the intercondylar notch, which has been shown to be associated with external tibial rotation and abduction.

  17. Mid-infrared pulsed laser ablation of the arterial wall. Mechanical origin of "acoustic" wall damage and its effect on wall healing

    NARCIS (Netherlands)

    van Erven, L.; van Leeuwen, T. G.; Post, M. J.; van der Veen, M. J.; Velema, E.; Borst, C.

    1992-01-01

    Pulsed mid-infrared lasers are an alternative to excimer lasers for transluminal angioplasty. The mid-infrared lasers, however, were reported to produce "acoustic" wall damage that might impair the immediate and long-term results. To study the immediate and long-term effects on the arterial wall,

  18. The Oscillatory Nature of Rotating Convection in Liquid Metal

    Science.gov (United States)

    Aurnou, J. M.; Bertin, V. L.; Grannan, A. M.

    2016-12-01

    Earth's magnetic field is assumed to be generated by fluid motions in its liquid metal core. In this fluid, the heat diffuses significantly more than momentum and thus, the ratio of these two diffusivities, the Prandtl number Pr=ν/Κ, is well below unity. The convective flow dynamics of liquid metal is very different from Pr ≈ 1 fluids like water and those used in current dynamo simulations. In order to characterize rapidly rotating thermal convection in low Pr number fluids, we have performed laboratory experiments in a cylinder using liquid gallium (Pr ≈ 0.023) as the working fluid. The Ekman number, which characterizes the effect of rotation, varies from E = 4 10-5 to 4 10-6 and the dimensionless buoyancy forcing (Rayleigh number, Ra) varies from Ra =3 105 to 2 107. Using heat transfer measurements (Nusselt number, Nu) as well as temperature measurements within the fluid, we characterize the different styles of low Pr rotating convective flow. The convection threshold is first overcome in the form of a container scale inertial oscillatory mode. At stronger forcing, wall-localized modes are identified for the first time in liquid metal laboratory experiments. These wall modes coexist with the bulk inertial oscillatory modes. When the strengh of the buoyancy increases, the bulk flow becomes turbulent while the wall modes remain. Our results imply that rotating convective flows in liquid metals do not develop in the form of quasi-steady columns, as in Pr ≈ 1 dynamo models, but in the form of oscillatory motions. Therefore, the flows that drive thermally-driven dynamo action in low Pr geophysical and astrophysical fluids can differ substantively than those occuring in current-day Pr ≈ 1 numerical models. In addition, our results suggest that relatively low wavenumber, wall-attached modes may be dynamically important in rapidly-rotating convection in liquid metals.

  19. A thick-walled sphere rotating in a uniform magnetic field: The next step to de-spin a space object

    Science.gov (United States)

    Nurge, Mark A.; Youngquist, Robert C.; Caracciolo, Ryan A.; Peck, Mason; Leve, Frederick A.

    2017-08-01

    Modeling the interaction between a moving conductor and a static magnetic field is critical to understanding the operation of induction motors, eddy current braking, and the dynamics of satellites moving through Earth's magnetic field. Here, we develop the case of a thick-walled sphere rotating in a uniform magnetic field, which is the simplest, non-trivial, magneto-statics problem that leads to complete closed-form expressions for the resulting potentials, fields, and currents. This solution requires knowledge of all of Maxwell's time independent equations, scalar and vector potential equations, and the Lorentz force law. The paper presents four cases and their associated experimental results, making this topic appropriate for an advanced student lab project.

  20. Study on wall recycling behaviour in CPD spherical tokamak

    International Nuclear Information System (INIS)

    Bhattacharyay, R.; Zushi, H.; Hirooka, Y.; Sakamoto, M.; Yoshinaga, T.; Okamoto, K.; Kawasaki, S.; Hanada, K.; Sato, K.N.; Nakamura, K.; Idei, H.; Ryoukai, T.; Nakashima, H.; Higashijima, A.

    2008-01-01

    Experiments to study wall recycling behaviour have been performed in the small spherical tokamak compact plasma-wall interaction experimental device (CPD) from the viewpoint of global as well as local plasma wall interaction condition. Electron cyclotron resonance (ECR) plasma of typically ∼50 to 400 ms duration is produced using ∼40 to 80 kW RF power. In order to study the global wall recycling behaviour, pressure measurements are carried out just before and after the ECR plasma in the absence of any external pumping. The recycling behaviour is found to change from release to pumping beyond a certain level of pressure value which is again found to be a function of shot history. The real-time local wall behaviour is studied in similar RF plasma using a rotating tungsten limiter, actively coated with lithium. Measurement of H α light intensity in front of the rotating surface has indicated a clear reduction (∼10%) in the steady-state hydrogen recycling with continuous Li gettering of several minutes

  1. Effect of metallic walls on dynamos generated by laminar boundary-driven flow in a spherical domain.

    Science.gov (United States)

    Guervilly, Céline; Wood, Toby S; Brummell, Nicholas H

    2013-11-01

    We present a numerical study of dynamo action in a conducting fluid encased in a metallic spherical shell. Motions in the fluid are driven by differential rotation of the outer metallic shell, which we refer to as "the wall." The two hemispheres of the wall are held in counter-rotation, producing a steady, axisymmetric interior flow consisting of differential rotation and a two-cell meridional circulation with radial inflow in the equatorial plane. From previous studies, this type of flow is known to maintain a stationary equatorial dipole by dynamo action if the magnetic Reynolds number is larger than about 300 and if the outer boundary is electrically insulating. We vary independently the thickness, electrical conductivity, and magnetic permeability of the wall to determine their effect on the dynamo action. The main results are the following: (a) Increasing the conductivity of the wall hinders the dynamo by allowing eddy currents within the wall, which are induced by the relative motion of the equatorial dipole field and the wall. This processes can be viewed as a skin effect or, equivalently, as the tearing apart of the dipole by the differential rotation of the wall, to which the field lines are anchored by high conductivity. (b) Increasing the magnetic permeability of the wall favors dynamo action by constraining the magnetic field lines in the fluid to be normal to the wall, thereby decoupling the fluid from any induction in the wall. (c) Decreasing the wall thickness limits the amplitude of the eddy currents, and is therefore favorable for dynamo action, provided that the wall is thinner than the skin depth. We explicitly demonstrate these effects of the wall properties on the dynamo field by deriving an effective boundary condition in the limit of vanishing wall thickness.

  2. Effects of rotation on flow in an asymmetric rib-roughened duct: LES study

    International Nuclear Information System (INIS)

    Borello, D.; Salvagni, A.; Hanjalić, K.

    2015-01-01

    Highlights: • Ribbed duct reproduces most of the phenomena occurring in internal cooling channels of blade turbines (rotor and stator). • LES analysis of the flow in a ribbed duct was carried out aiming at detecting the influence of rotation on the turbulence. • In destabilizing conditions, rotation enhances turbulence close to the ribbed duct thus enhancing removal of fluid from the wall and improving mixing. • In stabilizing conditions, turbulence is suppressed by rotation close to the ribbed wall. - Abstract: We report on large-eddy simulations (LES) of fully-developed asymmetric flow in a duct of a rectangular cross-section in which square-sectioned, equally-spaced ribs oriented perpendicular to the flow direction, were mounted on one of the walls. The configuration mimics a passage of internal cooling of a gas-turbine blade. The duct flow at a Reynolds number Re = 15,000 (based on hydraulic diameter D_h and bulk flow velocity U_0) was subjected to clock-wise (stabilising) and anti-clock-wise (destabilising) orthogonal rotation at a moderate rotational number Ro = ΩD_h/U_0 = 0.3, where Ω is the angular velocity. The LES results reproduced well the available experimental results of Coletti et al. (2011) (in the mid-plane adjacent to the ribbed wall) and provided insight into the whole duct complementing the reference PIV measurement. We analyzed the effects of stabilising and destabilising rotation on the flow, vortical structures and turbulence statistics by comparison with the non-rotating case. The analysis includes the identification of depth of penetration of the rib-effects into the bulk flow, influence of flow three-dimensionality and the role of secondary motions, all shown to be strongly affected by the rotation and its direction.

  3. Effects of centrifugal modification of magnetohydrodynamic equilibrium on resistive wall mode stability

    International Nuclear Information System (INIS)

    Shiraishi, J.; Aiba, N.; Miyato, N.; Yagi, M.

    2014-01-01

    Toroidal rotation effects are self-consistently taken into account not only in the linear magnetohydrodynamic (MHD) stability analysis but also in the equilibrium calculation. The MHD equilibrium computation is affected by centrifugal force due to the toroidal rotation. To study the toroidal rotation effects on resistive wall modes (RWMs), a new code has been developed. The RWMaC modules, which solve the electromagnetic dynamics in vacuum and the resistive wall, have been implemented in the MINERVA code, which solves the Frieman–Rotenberg equation that describes the linear ideal MHD dynamics in a rotating plasma. It is shown that modification of MHD equilibrium by the centrifugal force significantly reduces growth rates of RWMs with fast rotation in the order of M 2  = 0.1 where M is the Mach number. Moreover, it can open a stable window which does not exist under the assumption that the rotation affects only the linear dynamics. The rotation modifies the equilibrium pressure gradient and current density profiles, which results in the change of potential energy including rotational effects. (paper)

  4. Proposal of cancer therapy system without rotating gantry

    International Nuclear Information System (INIS)

    Kodaira, Masanobu

    2002-01-01

    Beam therapy is one of useful methods for cancer therapy. Many results in National Institute of Radiological Sciences (NIRS) show many abilities of beam therapy for cancer therapy. In Japan, several beam therapy facilities are constructed or under construction. If its construction budget becomes to be smaller, beam therapy may be used as the general cancer therapy. But in the present beam therapy facilities, the budget of its construction is very large. One of the reasons of big budget is the construction of the big buildings equipped with thick shielding walls. Most of space of the facilities with thick shielding walls is devoted to the treatment equipments such as rotating gantries and beam transport lines. This proposal is that using oblique beam line and rotating treatment bed, multi-portal irradiation is realized without rotating gantry. At the same time, we designed adequate beam lines to minimize the total facilities. (author)

  5. Three-dimensional rotating flow of MHD single wall carbon nanotubes over a stretching sheet in presence of thermal radiation

    Science.gov (United States)

    Nasir, Saleem; Islam, Saeed; Gul, Taza; Shah, Zahir; Khan, Muhammad Altaf; Khan, Waris; Khan, Aurang Zeb; Khan, Saima

    2018-05-01

    In this article the modeling and computations are exposed to introduce the new idea of MHD three-dimensional rotating flow of nanofluid through a stretching sheet. Single wall carbon nanotubes (SWCNTs) are utilized as a nano-sized materials while water is used as a base liquid. Single-wall carbon nanotubes (SWNTs) parade sole assets due to their rare structure. Such structure has significant optical and electronics features, wonderful strength and elasticity, and high thermal and chemical permanence. The heat exchange phenomena are deliberated subject to thermal radiation and moreover the impact of nanoparticles Brownian motion and thermophoresis are involved in the present investigation. For the nanofluid transport mechanism, we implemented the Xue model (Xue, Phys B Condens Matter 368:302-307, 2005). The governing nonlinear formulation based upon the law of conservation of mass, quantity of motion, thermal field and nanoparticles concentrations is first modeled and then solved by homotopy analysis method (HAM). Moreover, the graphical result has been exposed to investigate that in what manner the velocities, heat and nanomaterial concentration distributions effected through influential parameters. The mathematical facts of skin friction, Nusselt number and Sherwood number are presented through numerical data for SWCNTs.

  6. Heat transfer in rotating serpentine passages with trips normal to the flow

    Science.gov (United States)

    Wagner, J. H.; Johnson, B. V.; Graziani, R. A.; Yeh, F. C.

    1991-01-01

    Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large scale, multipass, heat transfer model with both radially inward and outward flow. Trip strips on the leading and trailing surfaces of the radial coolant passages were used to produce the rough walls. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant-to-wall temperature ratio, Rossby number, Reynolds number, and radius-to-passage hydraulic diameter ratio. The first three of these four parameters were varied over ranges which are typical of advanced gas turbine engine operating conditions. Results were correlated and compared to previous results from stationary and rotating similar models with trip strips. The heat transfer coefficients on surfaces, where the heat increased with rotation and buoyancy, varied by as much as a factor of four. Maximum values of the heat transfer coefficients with high rotation were only slightly above the highest levels obtained with the smooth wall model. The heat transfer coefficients on surfaces, where the heat transfer decreased with rotation, varied by as much as a factor of three due to rotation and buoyancy. It was concluded that both Coriolis and buoyancy effects must be considered in turbine blade cooling designs with trip strips and that the effects of rotation were markedly different depending upon the flow direction.

  7. Accelerated and Improved Differentiation of Retinal Organoids from Pluripotent Stem Cells in Rotating-Wall Vessel Bioreactors

    Directory of Open Access Journals (Sweden)

    Tyler DiStefano

    2018-01-01

    Full Text Available Pluripotent stem cells can be differentiated into 3D retinal organoids, with major cell types self-patterning into a polarized, laminated architecture. In static cultures, organoid development may be hindered by limitations in diffusion of oxygen and nutrients. Herein, we report a bioprocess using rotating-wall vessel (RWV bioreactors to culture retinal organoids derived from mouse pluripotent stem cells. Organoids in RWV demonstrate enhanced proliferation, with well-defined morphology and improved differentiation of neurons including ganglion cells and S-cone photoreceptors. Furthermore, RWV organoids at day 25 (D25 reveal similar maturation and transcriptome profile as those at D32 in static culture, closely recapitulating spatiotemporal development of postnatal day 6 mouse retina in vivo. Interestingly, however, retinal organoids do not differentiate further under any in vitro condition tested here, suggesting additional requirements for functional maturation. Our studies demonstrate that bioreactors can accelerate and improve organoid growth and differentiation for modeling retinal disease and evaluation of therapies.

  8. Wall roughness induces asymptotic ultimate turbulence

    Science.gov (United States)

    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.

  9. Polygons on a rotating fluid surface.

    Science.gov (United States)

    Jansson, Thomas R N; Haspang, Martin P; Jensen, Kåre H; Hersen, Pascal; Bohr, Tomas

    2006-05-05

    We report a novel and spectacular instability of a fluid surface in a rotating system. In a flow driven by rotating the bottom plate of a partially filled, stationary cylindrical container, the shape of the free surface can spontaneously break the axial symmetry and assume the form of a polygon rotating rigidly with a speed different from that of the plate. With water, we have observed polygons with up to 6 corners. It has been known for many years that such flows are prone to symmetry breaking, but apparently the polygonal surface shapes have never been observed. The creation of rotating internal waves in a similar setup was observed for much lower rotation rates, where the free surface remains essentially flat [J. M. Lopez, J. Fluid Mech. 502, 99 (2004). We speculate that the instability is caused by the strong azimuthal shear due to the stationary walls and that it is triggered by minute wobbling of the rotating plate.

  10. Feedback Control of Resistive Wall Modes in Slowly Rotating DIII-D Plasmas

    Science.gov (United States)

    Okabayashi, M.; Chance, M. S.; Takahashi, H.; Garofalo, A. M.; Reimerdes, H.; in, Y.; Chu, M. S.; Jackson, G. L.; La Haye, R. J.; Strait, E. J.

    2006-10-01

    In slowly rotating plasmas on DIII-D, the requirement of RWM control feedback have been identified, using a MHD code along with measured power supply characteristics. It was found that a small time delay is essential for achieving high beta if no rotation stabilization exists. The overall system delay or the band pass time constant should be in the range of 0.4 of the RWM growth time. Recently the control system was upgraded using twelve linear audio amplifiers and a faster digital control system, reducing the time-delay from 600 to 100 μs. The advantage has been clearly observed when the RWMs excited by ELMs were effectively controlled by feedback even if the rotation transiently slowed nearly to zero. This study provides insight on stability in the low- rotation plasmasw with balanced NBI in DIII-D and also in ITER.

  11. Plasma-wall interactions in RFX

    International Nuclear Information System (INIS)

    Valisa, M.; Bartiromo, R.; Carraro, L.

    1999-01-01

    Plasma wall interactions become a crucial issue in the Reversed Field Pinch RFX at high current (>0.7 MA). Wall-Mode Locking (WML) leads to carbon bloom, enhanced recycling and makes the density control very difficult to achieve. Several wall conditioning techniques have improved the capability of controlling recycling, especially boronization with diborane, but at 1 MA of plasma current removal of the WML becomes mandatory. Encouraging results have been achieved by rotating an externally induced perturbation that can unlock the WML. The strong impurity screening mechanism found at intermediate current does not degrade significantly at 1 MA. Modification of the tiles geometry could further reduce the power density dissipation and mitigate the PWI. (author)

  12. Plasma-wall interactions in RFX

    International Nuclear Information System (INIS)

    Valisa, M.; Bartiromo, R.; Carraro, L.

    2001-01-01

    Plasma wall interactions become a crucial issue in the Reversed Field Pinch RFX at high current (>0.7 MA). Wall-Mode Locking (WML) leads to carbon bloom, enhanced recycling and makes the density control very difficult to achieve. Several wall conditioning techniques have improved the capability of controlling recycling, especially boronisation with diborane, but at 1 MA of plasma current removal of the WML becomes mandatory. Encouraging results have been achieved by rotating an externally induced perturbation that can unlock the WML. The strong impurity screening mechanism found at intermediate current does not degrade significantly at 1 MA. Modification of the tiles geometry could further reduce the power density dissipation and mitigate the PWI. (author)

  13. Pressure Enhancement in Confined Fluids: Effect of Molecular Shape and Fluid-Wall Interactions.

    Science.gov (United States)

    Srivastava, Deepti; Santiso, Erik E; Gubbins, Keith E

    2017-10-24

    Recently, several experimental and simulation studies have found that phenomena that normally occur at extremely high pressures in a bulk phase can occur in nanophases confined within porous materials at much lower bulk phase pressures, thus providing an alternative route to study high-pressure phenomena. In this work, we examine the effect on the tangential pressure of varying the molecular shape, strength of the fluid-wall interactions, and pore width, for carbon slit-shaped pores. We find that, for multisite molecules, the presence of additional rotational degrees of freedom leads to unique changes in the shape of the tangential pressure profile, especially in larger pores. We show that, due to the direct relationship between the molecular density and the fluid-wall interactions, the latter have a large impact on the pressure tensor. The molecular shape and pore size have a notable impact on the layering of molecules in the pore, greatly influencing both the shape and scale of the tangential pressure profile.

  14. Gas rotation with M.H.D. drive

    International Nuclear Information System (INIS)

    1975-01-01

    A reactor vessel for electric discharges in rotating platina is described. The vessel wall consists of segmented electrodes. The electric potential can be varied per segment or block of segments. Further specifications are given

  15. Entropy generation impact on peristaltic motion in a rotating frame

    Directory of Open Access Journals (Sweden)

    H. Zahir

    Full Text Available Outcome of entropy generation in peristalsis of Casson fluid in a rotating frame is intended. Formulation is based upon thermal radiation, viscous dissipation and slip conditions of velocity and temperature. Lubrication approach is followed. The velocity components, temperature and trapping are examined. Specifically the outcomes of Taylor number, fluid parameter, slip parameters, Brinkman, radiation and compliant wall effects are focused. In addition entropy generation and Bejan numbers are examined. It is observed that entropy is controlled through slip effects. Keywords: Casson fluid, Radiative heat flux, Entropy generation, Rotating frame, Slip conditions, Wall properties

  16. The Eckert number phenomenon - experimental investigations of heat transfer on moving walls, e.g. rotating cylinders; Das Eckert-Zahl-Phaenomen - Experimentelle Untersuchungen zum Waermeuebergang an einer bewegten Wand am Modellfall eines rotierenden Zylinders

    Energy Technology Data Exchange (ETDEWEB)

    Gschwendtner, M.

    2000-07-01

    The Eckert number phenomenon - theoretically investigated by Geropp in 1969 - describes a turnover in heat transfer at a moving wall at an Eckert number EC=1. This report is the first to confirm the Eckert number phenomenon experimentally. Heat transfer on a heated, vertically rotating cylinder in a crossflow was investigated at extreme rotational speeds, i.e. in the range where the predicted phenomenon will occur. A heating concept had to be developed which allowed an input of heating power independent of rotational speed and which therefore had to be contact-free. The complex thermofluiddynamic processes in the boundary layer around the rotating cylinder were investigated and measured using predominantly optical measuring techniques. The results show that the temperature difference between the wall and the surrounding fluid had a significant effect on the predicted turnover of heat transfer at the wall. Moreover, maximum heat transfer occurs at an Eckert number Ec=0.3, which is of great importance for the cooling of hot surfaces in an airstream. [German] Das Eckert-Zahl-Phaenomen - von Geropp 1969 theoretisch untersucht - beschreibt den Umschlag des Waermeueberganges an einer bewegten Wand bei einer Eckert-ZahlEc{approx}1. In der vorliegenden Arbeit wird das Eckert-Zahl-Phaenomen zum ersten Mal experimentell bestaetigt. Dazu wurde der Waermeuebergang am Modellfall eines queransgestroemten, beheizten, vertikalrotierenden Zylinders untersucht. Aufgrund der fuer die Experimente notwendigen extremen Drehzahlen musste fuer die Zylinderheizung ein Konzept entwickelt werden, das eine beruehrungsfreie und damit drehzahlunabhaengige Leistungseinspeisung erlaubte. Mit vorwiegend optischen Messmethoden wurden die komplexen thermofluiddynamischen Vorgaenge in der Grenzschicht um den rotierenden Zylinder untersucht und vermessen. Die Ergebnisse zeigen u.a., dass die Temperaturdifferenz zwischen Wand und Umgebung von entscheidender Bedeutung fuer die Richtungsumkehr des

  17. Control of the Resistive Wall Mode with Internal Coils in the DIII-D Tokamak

    International Nuclear Information System (INIS)

    Okabayashi, M.; Bialek, J.; Bondeson, A.

    2005-01-01

    New coils were installed inside the vacuum vessel of the DIII-D device for producing nonaxisymmetric magnetic fields. These 'Internal-Coils' are predicted to stabilize the Resistive Wall Mode (RWM) branch of the long-wavelength external kink mode with plasma beta close to the ideal wall limit. Feedback using these new Internal-Coils was found to be more effective when compared with using the External-Coils located outside the vacuum vessel, because the location inside the vessel allows faster response and their geometry also couples better to the helical mode structure. A proper choice of feedback gain increased the plasma beta above the no-wall limit to C β ≥ 0.9, where C β is a measure of achievable beta above no-wall limit defined as (β-β no-wall.limit )/(β ideal.wall.limit )-)/(β no.wall.limit ). The feedback system with Internal-Coils can suppress the RWM up to the normalized growth rate γτ w > or ∼ 10 (τ w is the resistive flux penetration time of the wall). The feedback-driven dynamic error field correction helps to stabilize the RWM by reducing the rotational drag for Ω rot > Ω crit , where Ω rot is the angular rotation frequency of plasma and Ω crit is the critical value for the rotational stabilization. When Ω rot crit /2, the feedback system must stabilize the RWM mainly through direct magnetic control of the mode. The estimated Ω crit /Ω A is ∼ 2.5% by the MARS-F code analysis with experimentally observed profiles, where /Ω A is the Alfven angular rotational frequency at q 2 surface. The MARS-F code also predicts that for successful RWM magnetic feedback control the power supply characteristic time should be a fraction of the growth time of the targeted RWM. (author)

  18. Shear localization and effective wall friction in a wall bounded granular flow

    Science.gov (United States)

    Artoni, Riccardo; Richard, Patrick

    2017-06-01

    In this work, granular flow rheology is investigated by means of discrete numerical simulations of a torsional, cylindrical shear cell. Firstly, we focus on azimuthal velocity profiles and study the effect of (i) the confining pressure, (ii) the particle-wall friction coefficient, (iii) the rotating velocity of the bottom wall and (iv) the cell diameter. For small cell diameters, azimuthal velocity profiles are nearly auto-similar, i.e. they are almost linear with the radial coordinate. Different strain localization regimes are observed : shear can be localized at the bottom, at the top of the shear cell, or it can be even quite distributed. This behavior originates from the competition between dissipation at the sidewalls and dissipation in the bulk of the system. Then we study the effective friction at the cylindrical wall, and point out the strong link between wall friction, slip and fluctuations of forces and velocities. Even if the system is globally below the sliding threshold, force fluctuations trigger slip events, leading to a nonzero wall slip velocity and an effective wall friction coefficient different from the particle-wall one. A scaling law was found linking slip velocity, granular temperature in the main flow direction and effective friction. Our results suggest that fluctuations are an important ingredient for theories aiming to capture the interface rheology of granular materials.

  19. A rotating arc plasma invertor

    International Nuclear Information System (INIS)

    Reusch, M.F.; Jayaram, K.

    1987-02-01

    A device is described for the inversion of direct current to alternating current. The main feature is the use of a rotating plasma arc in crossed electric and magnetic fields as a switch. This device may provide an economic alternative to other inversion methods in some circumstances

  20. Toroidal rotation studies in KSTAR

    Science.gov (United States)

    Lee, S. G.; Lee, H. H.; Yoo, J. W.; Kim, Y. S.; Ko, W. H.; Terzolo, L.; Bitter, M.; Hill, K.; KSTAR Team

    2014-10-01

    Investigation of the toroidal rotation is one of the most important topics for the magnetically confined fusion plasma researches since it is essential for the stabilization of resistive wall modes and its shear plays an important role to improve plasma confinement by suppressing turbulent transport. The most advantage of KSTAR tokamak for toroidal rotation studies is that it equips two main diagnostics including the high-resolution X-ray imaging crystal spectrometer (XICS) and charge exchange spectroscopy (CES). Simultaneous core toroidal rotation and ion temperature measurements of different impurity species from the XICS and CES have shown in reasonable agreement with various plasma discharges in KSTAR. It has been observed that the toroidal rotation in KSTAR is faster than that of other tokamak devices with similar machine size and momentum input. This may due to an intrinsically low toroidal field ripple and error field of the KSTAR device. A strong braking of the toroidal rotation by the n = 1 non-resonant magnetic perturbations (NRMPs) also indicates these low toroidal field ripple and error field. Recently, it has been found that n = 2 NRMPs can also damp the toroidal rotation in KSTAR. The detail toroidal rotation studies will be presented. Work supported by the Korea Ministry of Science, ICT and Future Planning under the KSTAR project.

  1. A rotating helical sealing joint capable of partially melting

    International Nuclear Information System (INIS)

    Martin, Jean; Ollier, J.-L.; Petit, Paul.

    1973-01-01

    A coagulated rotating helical joint providing gas and liquid tightness along a rotating shaft, comprising: a metal sleeve connected to the wall through which passes the rotating sleeve, an intermediate sleeve made of a fusible material, inert with respect to the fluid to be sealingly retained, and finally the rotating shaft provided with an engraved helical thread in register with the intermediate sleeve. Means are provided for regulating the intermediate sleeve temperature so that a thin melted film is formed on said intermediate sleeve when in contact with the rotating threaded shaft. This can be applied in the nuclear industry, including cases when the intermediate sleeve is constituted by the fluid itself, then in the solid state [fr

  2. Nucleation of rotating crystals by Thiovulum majus bacteria

    Science.gov (United States)

    Petroff, A. P.; Libchaber, A.

    2018-01-01

    Thiovulum majus self-organize on glass surfaces into active two-dimensional crystals of rotating cells. Unlike classical crystals, these bacterial crystallites continuously rotate and reorganize as the power of rotating cells is dissipated by the surrounding flow. In this article, we describe the earliest stage of crystallization, the attraction of two bacteria into a hydrodynamically-bound dimer. This process occurs in three steps. First a free-swimming cell collides with the wall and becomes hydrodynamically bound to the two-dimensional surface. We present a simple model to understand how viscous forces localize cells near the chamber walls. Next, the cell diffuses over the surface for an average of 63+/- 6 s before escaping to the bulk fluid. The diffusion coefficient {D}{{eff}}=7.98 +/- 0.1 μ {{{m}}}2 {{{s}}}-1 of these 8.5 μ {{m}} diameter cells corresponds to a temperature of (4.16+/- 0.05)× {10}4 K, and thus cannot be explained by equilibrium fluctuations. Finally, two cells coalesce into a rotating dimer when the convergent flow created by each cell overwhelms their active Brownian motion. This occurs when cells diffuse to within a distance of 13.3 ± 0.2 μm of each other.

  3. Asymmetric driven dynamics of Dzyaloshinskii domain walls in ultrathin ferromagnetic strips with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Tejerina, L. [Dpto. Electricidad y Electrónica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid (Spain); Alejos, Ó., E-mail: oscaral@ee.uva.es [Dpto. Electricidad y Electrónica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid (Spain); Martínez, E. [Dpto. Física Aplicada, Facultad de Ciencias, Universidad de Salamanca, 37011 Salamanca (Spain); Muñoz, J.M. [Dpto. Electricidad y Electrónica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid (Spain)

    2016-07-01

    The dynamics of domain walls in ultrathin ferromagnetic strips with perpendicular magnetic anisotropy is studied from both numerical and analytical micromagnetics. The influence of a moderate interfacial Dzyaloshinskii–Moriya interaction associated to a bi-layer strip arrangement has been considered, giving rise to the formation of Dzyaloshinskii domain walls. Such walls possess under equilibrium conditions an inner magnetization structure defined by a certain orientation angle that make them to be considered as intermediate configurations between Bloch and Néel walls. Two different dynamics are considered, a field-driven and a current-driven dynamics, in particular, the one promoted by the spin torque due to the spin-Hall effect. Results show an inherent asymmetry associated with the rotation of the domain wall magnetization orientation before reaching the stationary regime, characterized by a constant terminal speed. For a certain initial DW magnetization orientation at rest, the rotation determines whether the reorientation of the DW magnetization prior to reach stationary motion is smooth or abrupt. This asymmetry affects the DW motion, which can even reverse for a short period of time. Additionally, it is found that the terminal speed in the case of the current-driven dynamics may depend on either the initial DW magnetization orientation at rest or the sign of the longitudinally injected current. - Highlights: • The asymmetric response of domain walls in bilayer strips with PMA is studied. • Out-of-plane fields and SHE longitudinal currents are applied. • The response is associated to the rotation of the domain wall inner magnetization. • Clockwise and counter-clockwise magnetization rotations are not equivalent. • The asymmetry results in different travelled distances and/or terminal speeds.

  4. Asymmetric driven dynamics of Dzyaloshinskii domain walls in ultrathin ferromagnetic strips with perpendicular magnetic anisotropy

    International Nuclear Information System (INIS)

    Sánchez-Tejerina, L.; Alejos, Ó.; Martínez, E.; Muñoz, J.M.

    2016-01-01

    The dynamics of domain walls in ultrathin ferromagnetic strips with perpendicular magnetic anisotropy is studied from both numerical and analytical micromagnetics. The influence of a moderate interfacial Dzyaloshinskii–Moriya interaction associated to a bi-layer strip arrangement has been considered, giving rise to the formation of Dzyaloshinskii domain walls. Such walls possess under equilibrium conditions an inner magnetization structure defined by a certain orientation angle that make them to be considered as intermediate configurations between Bloch and Néel walls. Two different dynamics are considered, a field-driven and a current-driven dynamics, in particular, the one promoted by the spin torque due to the spin-Hall effect. Results show an inherent asymmetry associated with the rotation of the domain wall magnetization orientation before reaching the stationary regime, characterized by a constant terminal speed. For a certain initial DW magnetization orientation at rest, the rotation determines whether the reorientation of the DW magnetization prior to reach stationary motion is smooth or abrupt. This asymmetry affects the DW motion, which can even reverse for a short period of time. Additionally, it is found that the terminal speed in the case of the current-driven dynamics may depend on either the initial DW magnetization orientation at rest or the sign of the longitudinally injected current. - Highlights: • The asymmetric response of domain walls in bilayer strips with PMA is studied. • Out-of-plane fields and SHE longitudinal currents are applied. • The response is associated to the rotation of the domain wall inner magnetization. • Clockwise and counter-clockwise magnetization rotations are not equivalent. • The asymmetry results in different travelled distances and/or terminal speeds.

  5. Oscillatory Convection in Rotating Liquid Metals

    Science.gov (United States)

    Bertin, Vincent; Grannan, Alex; Aurnou, Jonathan

    2016-11-01

    We have performed laboratory experiments in a aspect ratio Γ = 2 cylinder using liquid gallium (Pr = 0 . 023) as the working fluid. The Ekman number varies from E = 4 ×10-5 to 4 ×10-6 and the Rayleigh number varies from Ra = 3 ×105 to 2 ×107 . Using heat transfer and temperature measurements within the fluid, we characterize the different styles of low Pr rotating convective flow. The convection threshold is first overcome in the form of a container scale inertial oscillatory mode. At stronger forcing, wall-localized modes develop, coexisting with the inertial oscillatory modes in the bulk. When the strength of the buoyancy increases further, the bulk flow becomes turbulent while the wall modes remain. Our results imply that rotating convective flows in liquid metals do not develop in the form of quasi-steady columns, as in Pr = 1 planetary and stellar dynamo models, but in the form of oscillatory motions. Therefore, convection driven dynamo action in low Pr fluids can differ substantively than that occurring in typical Pr = 1 numerical models. Our results also suggest that low wavenumber, wall modes may be dynamically and observationally important in liquid metal dynamo systems. We thank the NSF Geophysics Program for support of this project.

  6. Effect of rotating electric field on 3D complex (dusty) plasma

    Science.gov (United States)

    Wörner, L.; Nosenko, V.; Ivlev, A. V.; Zhdanov, S. K.; Thomas, H. M.; Morfill, G. E.; Kroll, M.; Schablinski, J.; Block, D.

    2011-06-01

    The effect of rotating electric field on 3D particle clusters suspended in rf plasma was studied experimentally. Spheroidal clusters were suspended inside a glass box mounted on the lower horizontal rf electrode, with gravity partially balanced by thermophoretic force. Clusters rotated in the horizontal plane, in response to rotating electric field that was created inside the box using conducting coating on its inner surfaces ("rotating wall" technique). Cluster rotation was always in the direction of applied field and had a shear in the vertical direction. The angular speed of rotation was 104-107 times lower than applied frequency. The experiment is compared to a recent theory.

  7. Low frequency oscillatory flow in a rotating curved pipe

    Institute of Scientific and Technical Information of China (English)

    陈华军; 章本照; 苏霄燕

    2003-01-01

    The low frequency oscillatory flow in a rotating curved pipe was studied by using the method of bi-parameter perturbation. Perturbation solutions up to the second order were obtained and the effects of rotation on the low frequency oscillatory flow were examined in detail. The results indicated that there exists evident difference between the low frequency oscillatory flow in a rotating curved pipe and in a curved pipe without rotation. During a period, four secondary vortexes may exist on the circular cross-section and the distribution of axial velocity and wall shear stress are related to the ratio of the Coriolis force to centrifugal force and the axial pressure gradient.

  8. Rotating solitary wave at the wall of a cylindrical container

    KAUST Repository

    Amaouche, Mustapha; Ait Abderrahmane, Hamid; Vatistas, Georgios H.

    2013-01-01

    This paper deals with the theoretical modeling of a rotating solitary surface wave that was observed during water drainage from a cylindrical reservoir, when shallow water conditions were reached. It represents an improvement of our previous study

  9. Pattern formation and three-dimensional instability in rotating flows

    Science.gov (United States)

    Christensen, Erik A.; Aubry, Nadine; Sorensen, Jens N.

    1997-03-01

    A fluid flow enclosed in a cylindrical container where fluid motion is created by the rotation of one end wall as a centrifugal fan is studied. Direct numerical simulations and spatio-temporal analysis have been performed in the early transition scenario, which includes a steady-unsteady transition and a breakdown of axisymmetric to three-dimensional flow behavior. In the early unsteady regime of the flow, the central vortex undergoes a vertical beating motion, accompanied by axisymmetric spikes formation on the edge of the breakdown bubble. As traveling waves, the spikes move along the central vortex core toward the rotating end-wall. As the Reynolds number is increased further, the flow undergoes a three-dimensional instability. The influence of the latter on the previous patterns is studied.

  10. Wall thickness tests by means of rotating electrodynamic transducers

    International Nuclear Information System (INIS)

    Hueschelrath, G.

    1986-01-01

    For about three years, the EROT system has been employed for measuring wall thicknesses on pipes of ferritic steels. The experience gathered and the degree of reliability reached up to now are definitely encouraging, so that an increased use of electrodynamic transducers can be expected for measuring pipes with outside diameters of up to 22 inches. (orig.) [de

  11. Gravity currents in rotating channels. Part 1. Steady-state theory

    Science.gov (United States)

    Hacker, J. N.; Linden, P. F.

    2002-04-01

    A theory is developed for the speed and structure of steady-state non-dissipative gravity currents in rotating channels. The theory is an extension of that of Benjamin (1968) for non-rotating gravity currents, and in a similar way makes use of the steady-state and perfect-fluid (incompressible, inviscid and immiscible) approximations, and supposes the existence of a hydrostatic ‘control point’ in the current some distance away from the nose. The model allows for fully non-hydrostatic and ageostrophic motion in a control volume V ahead of the control point, with the solution being determined by the requirements, consistent with the perfect-fluid approximation, of energy and momentum conservation in V, as expressed by Bernoulli's theorem and a generalized flow-force balance. The governing parameter in the problem, which expresses the strength of the background rotation, is the ratio W = B/R, where B is the channel width and R = (g[prime prime or minute]H)1/2/f is the internal Rossby radius of deformation based on the total depth of the ambient fluid H. Analytic solutions are determined for the particular case of zero front-relative flow within the gravity current. For each value of W there is a unique non-dissipative two-layer solution, and a non-dissipative one-layer solution which is specified by the value of the wall-depth h0. In the two-layer case, the non-dimensional propagation speed c = cf(g[prime prime or minute]H)[minus sign]1/2 increases smoothly from the non-rotating value of 0.5 as W increases, asymptoting to unity for W [rightward arrow] [infty infinity]. The gravity current separates from the left-hand wall of the channel at W = 0.67 and thereafter has decreasing width. The depth of the current at the right-hand wall, h0, increases, reaching the full depth at W = 1.90, after which point the interface outcrops on both the upper and lower boundaries, with the distance over which the interface slopes being 0.881R. In the one-layer case, the wall

  12. A chief of service rotation as an alternative approach to pediatric otolaryngology inpatient care.

    Science.gov (United States)

    Adil, Eelam; Xiao, Roy; McGill, Trevor; Rahbar, Reza; Cunningham, Michael

    2014-09-01

    provided supervised evaluations and continuity of care. This rotating hospitalist program is a viable alternative to the full-time hospitalist staff model.

  13. Alternativa estructural de refuerzo horizontal en muros de mampostería Structural alternative of horizontal reinforcement in masonry walls

    Directory of Open Access Journals (Sweden)

    Diego Fernando Páez Moreno

    2009-01-01

    Full Text Available La implementación de refuerzo horizontal en muros de mampostería con ladrillo macizo de arcilla cocida es una técnica empleada en varios países. En este trabajo se propone un análisis para muros de mampostería representativos de la ciudad de Tunja con la implementación de grafiles de acero como alternativa de refuerzo horizontal. Este estudio involucra la definición de los tipos de materiales a emplear, las características de los muros a ensayar y las variables que se deben aplicar, tanto en los muros como en la ejecución del ensayo de compresión diagonal, que define tipos de muros con características propias de refuerzo. Los resultados del proceso de análisis del comportamiento individual y general de los muros de mampostería sometidos al ensayo de compresión diagonal permiten identificar la variación del esfuerzo cortante representativo para cada tipo de muro, en relación con el refuerzo empleado en los diferentes modelos y la tipología de falla.Implementation of horizontal reinforcement in masonry walls with solid cooked clay bricks is a commonly used technique in several countries. This article is intended to analyze masonry walls representatives of Tunja City, with implementation of small steel bars as an alternative of horizontal reinforcement. This study involves definition of types of materials to be used, characteristics of walls to be tested, and variables which should be applied in both walls and during the execution of the diagonal compression test which defines the types of walls with own characteristics of reinforcement. Results from individual and general behavior analysis process of masonry walls subject to diagonal compression tests allow identifying variation of shear stress for each kind of wall, in relation to reinforcement used in several models and failure typology.

  14. The Mechanical Properties of a Wall-Climbing Caterpillar Robot: Analysis and Experiment

    Directory of Open Access Journals (Sweden)

    Kun Wang

    2013-01-01

    Full Text Available This paper builds the kinematic model of a wall-climbing caterpillar robot to reveal the validity and the benefits of the closed-chain kinematics of the four-linkage mechanism to a crawling gait. The caterpillar robot can climb on a vertical wall by coordinating the rotations of one active joint and three passive joints. The mechanical property of the closed-chain kinematics of the four-linkage model is analysed. Furthermore, the relation between the driving joint torque and joint angle in the wall-climbing process is deduced based on the coplanar arbitrary force system. Afterwards, the joint control method is discussed in order to coordinate the rotation of the four joints so as to realize a reasonable wall climbing gait. To testify to the availability of the closed-chain four-linkage model, a wall-climbing caterpillar robot is developed with three different adhesion modules based on the vibrating suction method. A successful wall-climbing test confirms both the practicality of the four-linkage model and the validity of the adhesion modules based on the vibrating suction method. The results also show the reasonableness of the driving joint selection rule for ensuring a safe and reliable wall-climbing procedure.

  15. Hanging-wall deformation above a normal fault: sequential limit analyses

    Science.gov (United States)

    Yuan, Xiaoping; Leroy, Yves M.; Maillot, Bertrand

    2015-04-01

    The deformation in the hanging wall above a segmented normal fault is analysed with the sequential limit analysis (SLA). The method combines some predictions on the dip and position of the active fault and axial surface, with geometrical evolution à la Suppe (Groshong, 1989). Two problems are considered. The first followed the prototype proposed by Patton (2005) with a pre-defined convex, segmented fault. The orientation of the upper segment of the normal fault is an unknown in the second problem. The loading in both problems consists of the retreat of the back wall and the sedimentation. This sedimentation starts from the lowest point of the topography and acts at the rate rs relative to the wall retreat rate. For the first problem, the normal fault either has a zero friction or a friction value set to 25o or 30o to fit the experimental results (Patton, 2005). In the zero friction case, a hanging wall anticline develops much like in the experiments. In the 25o friction case, slip on the upper segment is accompanied by rotation of the axial plane producing a broad shear zone rooted at the fault bend. The same observation is made in the 30o case, but without slip on the upper segment. Experimental outcomes show a behaviour in between these two latter cases. For the second problem, mechanics predicts a concave fault bend with an upper segment dip decreasing during extension. The axial surface rooting at the normal fault bend sees its dips increasing during extension resulting in a curved roll-over. Softening on the normal fault leads to a stepwise rotation responsible for strain partitioning into small blocks in the hanging wall. The rotation is due to the subsidence of the topography above the hanging wall. Sedimentation in the lowest region thus reduces the rotations. Note that these rotations predicted by mechanics are not accounted for in most geometrical approaches (Xiao and Suppe, 1992) and are observed in sand box experiments (Egholm et al., 2007, referring

  16. Three-dimensional, three-component wall-PIV

    Science.gov (United States)

    Berthe, André; Kondermann, Daniel; Christensen, Carolyn; Goubergrits, Leonid; Garbe, Christoph; Affeld, Klaus; Kertzscher, Ulrich

    2010-06-01

    This paper describes a new time-resolved three-dimensional, three-component (3D-3C) measurement technique called wall-PIV. It was developed to assess near wall flow fields and shear rates near non-planar surfaces. The method is based on light absorption according to Beer-Lambert’s law. The fluid containing a molecular dye and seeded with buoyant particles is illuminated by a monochromatic, diffuse light. Due to the dye, the depth of view is limited to the near wall layer. The three-dimensional particle positions can be reconstructed by the intensities of the particle’s projection on an image sensor. The flow estimation is performed by a new algorithm, based on learned particle trajectories. Possible sources of measurement errors related to the wall-PIV technique are analyzed. The accuracy analysis was based on single particle experiments and a three-dimensional artificial data set simulating a rotating sphere.

  17. Compensated pulsed alternator

    International Nuclear Information System (INIS)

    Weldon, W.F.; Driga, M.D.; Woodson, H.H.

    1980-01-01

    This invention relates to an electromechanical energy converter with inertial energy storage. The device, a single phase, two or multi-pole alternator with stationary field coils, and a rotating armature is provided. The rotor itself may be of laminated steel for slower pulses or for faster pulses should be nonmagnetic and electrically nonconductive in order to allow rapid penetration of the field as the armature coil rotates. The armature coil comprises a plurality of power generating conductors mounted on the rotor. The alternator may also include a stationary or counterrotating compensating coil to increase the output voltage thereof and to reduce the internal impedance of the alternator at the moment of peak output. As the machine voltage rises sinusoidally, an external trigger switch is adapted to be closed at the appropriate time to create the desired output current from said alternator to an external load circuit, and as the output current passes through zero a self-commutating effect is provided to allow the switch to disconnect the generator from the external circuit

  18. Wall stabilization of high beta plasmas in DIII-D

    International Nuclear Information System (INIS)

    Taylor, T.S.; Strait, E.J.; Lao, L.L.; Turnbull, A.D.; Burrell, K.H.; Chu, M.S.; Ferron, J.R.; Groebner, R.J.; La Haye, R.J.; Mauel, M.

    1995-02-01

    Detailed analysis of recent high beta discharges in the DIII-D tokamak demonstrates that the resistive vacuum vessel can provide stabilization of low n magnetohydrodynamic (MHD) modes. The experimental beta values reaching up to β T = 12.6% are more than 30% larger than the maximum stable beta calculated with no wall stabilization. Plasma rotation is essential for stabilization. When the plasma rotation slows sufficiently, unstable modes with the characteristics of the predicted open-quotes resistive wallclose quotes mode are observed. Through slowing of the plasma rotation between the q = 2 and q = 3 surfaces with the application of a non-axisymmetric field, the authors have determined that the rotation at the outer rational surfaces is most important, and that the critical rotation frequency is of the order of Ω/2π = 1 kHz

  19. Large Scale Flutter Data for Design of Rotating Blades Using Navier-Stokes Equations

    Science.gov (United States)

    Guruswamy, Guru P.

    2012-01-01

    A procedure to compute flutter boundaries of rotating blades is presented; a) Navier-Stokes equations. b) Frequency domain method compatible with industry practice. Procedure is initially validated: a) Unsteady loads with flapping wing experiment. b) Flutter boundary with fixed wing experiment. Large scale flutter computation is demonstrated for rotating blade: a) Single job submission script. b) Flutter boundary in 24 hour wall clock time with 100 cores. c) Linearly scalable with number of cores. Tested with 1000 cores that produced data in 25 hrs for 10 flutter boundaries. Further wall-clock speed-up is possible by performing parallel computations within each case.

  20. Investigation of intrinsic toroidal rotation scaling in KSTAR

    Science.gov (United States)

    Yoo, J. W.; Lee, S. G.; Ko, S. H.; Seol, J.; Lee, H. H.; Kim, J. H.

    2017-07-01

    The behaviors of an intrinsic toroidal rotation without any external momentum sources are investigated in KSTAR. In these experiments, pure ohmic discharges with a wide range of plasma parameters are carefully selected and analyzed to speculate an unrevealed origin of toroidal rotation excluding any unnecessary heating sources, magnetic perturbations, and strong magneto-hydrodynamic activities. The measured core toroidal rotation in KSTAR is mostly in the counter-current direction and its magnitude strongly depends on the ion temperature divided by plasma current (Ti/IP). Especially the core toroidal rotation in the steady-state is well fitted by Ti/IP scaling with a slope of ˜-23, and the possible explanation of the scaling is compared with various candidates. As a result, the calculated offset rotation could not explain the measured core toroidal rotation since KSTAR has an extremely low intrinsic error field. For the stability conditions for ion and electron turbulences, it is hard to determine a dominant turbulence mode in this study. In addition, the intrinsic toroidal rotation level in ITER is estimated based on the KSTAR scaling since the intrinsic rotation plays an important role in stabilizing resistive wall modes for future reference.

  1. Rotation, Stability and Transport

    Energy Technology Data Exchange (ETDEWEB)

    Connor, J. W.

    2007-07-01

    Tokamak plasmas can frequently exhibit high levels of rotation and rotation shear. This can usually be attributed to various sources: injection of momentum, e.g. through neutral beams, flows driven by plasma gradients or torques resulting from non-ambipolar particle loss; however, the source sometimes remains a mystery, such as the spontaneous rotation observed in Ohmic plasmas. The equilibrium rotation profile is given by the balance of these sources with transport and other losses; the edge boundary conditions can play an important role in determining this profile . Such plasma rotation, particularly sheared rotation, is predicted theoretically to have a significant influence on plasma behaviour. In the first place, sonic flows can significantly affect tokamak equilibria and neoclassical transport losses. However, the influence of rotation on plasma stability and turbulence is more profound. At the macroscopic level it affects the behaviour of the gross MHD modes that influence plasma operational limits. This includes sawteeth, the seeding of neoclassical tearing modes, resistive wall modes and the onset of disruptions through error fields, mode locking and reconnection. At the microscopic level it has a major effect on the stability of ballooning modes, both ideal MHD and drift wave instabilities such as ion temperature gradient (ITG) modes. In the non-linear state, as unstable drift waves evolve into turbulent structures, sheared rotation also tears apart eddies, thereby reducing the resulting transport. There is considerable experimental evidence for these effects on both MHD stability and plasma confinement. In particular, the appearance of improved confinement modes with transport barriers, such as edge H-mode barriers and internal transport barriers (ITBs) appears to correlate well with the presence of sheared plasma rotation. This talk will describe the theory underlying some of these phenomena involving plasma rotation, on both macroscopic and microscopic

  2. Effect of Wall Friction and Vortex Generation on Radial Void Distribution The Wall - Vortex Effect

    Energy Technology Data Exchange (ETDEWEB)

    Rouhani, Zia

    1974-09-15

    Arguments are presented to prove the existence of rolling vortices in two-phase flow. In liquid phase they will appear in a boundary layer near the walls while in the continuous vapor phase they will occur near the interface with a liquid film. The intensity and size of these vortices are expected to depend on the local velocity gradients normal to the walls. A discussion is given of the interaction between the rotational field associated with such vortices and bubbles in liquid flow or droplets in vapor-flow. This interaction is called the wall-vortex effect. It appears that several, apparently unrelated, phenomena observed in two-phase flow systems may be interpreted in terms of this mechanism. Among these are: Radial void peaking near the walls; Slip ratios less than unity observed even in vertical upward flow; Reduced droplet diffusion near the liquid film; Reduced vapor mixing between subchannels at low steam qualities; and Accelerated flashing process in flow of depressurized liquid. Finally, a comparison with the well-known Magnus effect is also included

  3. MHD rotating flow and heat transfer through a channel with Hall effects

    International Nuclear Information System (INIS)

    Ghosh, Sushil Kumar

    2016-01-01

    The present investigation is the flow and heat transfer of a viscous fluid through a rotating channel about the vertical axis under the influence of transverse magnetic field. The linear temperature dependent density has been introduced along with the induced magnetic field in horizontal directions. To study the temperature distribution, the energy equation consisting of viscous dissipation and joule heating term is solved analytically. The velocity distribution in axial and vertical directions is found to be interesting such as the magnetic Reynolds number and the parameter appears due to buoyancy forces have a substantial contribution to influence the flow pattern. Also the results obtained in the study for magnetic induction variables as well as temperature distribution put forward some significant insight in the fluid flow and heat transfer. The important observation of the present study is that the temperature distribution takes the higher values in the vicinity of the upper wall and this happens due to the fact of buoyancy force and channel rotation. This is a key parameter to worm up or cool down the fluid in a useful purposes. - Highlights: • The important observation of the present study is that the temperature distribution takes the higher values in the vicinity of the upper wall and this happens due to the fact of buoyancy force and channel rotation. • Buoyancy is a key parameter to worm up or cool down the fluid in useful purposes. • It may be predicted that the effect of buoyancy force and magnetic induction force suppress the flow at the lower wall and the effect of the forces lost its potential at the layers near to the upper walls. • It may suggest that the bouncy effect has more prominent role in the fluid flow phenomena as well as heat transfer than magnetic induction and Lorentz force. • The rotation enhances the advantage of circulation of fluid in up and down and tries to make the heat balance within the layers. Our result is true

  4. Alternative methodology for assessing part-through-wall cracks in carbon steel bends removed from Point Lepreau Generating Station

    Energy Technology Data Exchange (ETDEWEB)

    Duan Xinjian, E-mail: duanx@aecl.c [Senior Engineer, Reactor Engineering Department, Atomic Energy of Canada Ltd., Mississauga, ON (Canada); Kozluk, Michael J., E-mail: kozlukm@aecl.c [Independent Consultant, Oakville, ON (Canada); Gendron, Tracy [Manager-HTS Materials Integrity, Atomic Energy of Canada Ltd., Chalk River, ON (Canada); Slade, John [Senior Technical Advisor, Point Lepreau Generating Station, Lepreau, NB (Canada)

    2011-03-15

    In 2008 April Point Lepreau Generating Station entered an extended refurbishment outage that will involve the replacement of key reactor components (fuel channels and connecting feeder pipes). Prior to the refurbishment outage, New Brunswick Power Nuclear had been successfully managing intergranular, axial cracking of carbon steel feeder piping, that were also experiencing thinning, in the Point Lepreau Generating Station, primarily by an aggressive program of inspection, repair and testing of ex-service material. For the previous three maintenance outages, a probabilistic safety evaluation (PSE) had been used to demonstrate that annual inspection of the highest risk locations maintains the nuclear safety risk from cracking at an acceptably low level. The PSE makes use of the Failure Assessment Diagram (FAD) model to predict the failure of part-through-wall cracks. Burst-pressure testing of two ex-service feeder pipe sections with part-through-wall cracks showed that this FAD model significantly under predicts the failure pressure measured in the component tests. Use of this FAD model introduces undesirable conservatism into PSE assessments that are used to optimize feeder piping inspection and maintenance plans. This paper describes an alternative finite element approach, which could be used to provide more representative structural models for use in PSE assessments. This alternative approach employs the elasto-plastic large strain finite element formulation; uses representative material properties; considers the spatial microstructural distribution; accounts for the effect of work hardening rate; models all deformation processes, i.e., uniform deformation, localized necking, and failure imitation and propagation. Excellent pre-test prediction was shown for the burst-pressure test performed in 2006. Although cold-worked feeder bends have reduced fracture toughness compared to the parent straight pipe, post-test metallurgical examinations showed that failure at the

  5. Multi-scale phenomena of rotation-modified mode-2 internal waves

    Science.gov (United States)

    Deepwell, David; Stastna, Marek; Coutino, Aaron

    2018-03-01

    We present high-resolution, three-dimensional simulations of rotation-modified mode-2 internal solitary waves at various rotation rates and Schmidt numbers. Rotation is seen to change the internal solitary-like waves observed in the absence of rotation into a leading Kelvin wave followed by Poincaré waves. Mass and energy is found to be advected towards the right-most side wall (for a Northern Hemisphere rotation), leading to increased amplitude of the leading Kelvin wave and the formation of Kelvin-Helmholtz (K-H) instabilities on the upper and lower edges of the deformed pycnocline. These fundamentally three-dimensional instabilities are localized within a region near the side wall and intensify in vigour with increasing rotation rate. Secondary Kelvin waves form further behind the wave from either resonance with radiating Poincaré waves or the remnants of the K-H instability. The first of these mechanisms is in accord with published work on mode-1 Kelvin waves; the second is, to the best of our knowledge, novel to the present study. Both types of secondary Kelvin waves form on the same side of the channel as the leading Kelvin wave. Comparisons of equivalent cases with different Schmidt numbers indicate that while adopting a numerically advantageous low Schmidt number results in the correct general characteristics of the Kelvin waves, excessive diffusion of the pycnocline and various density features precludes accurate representation of both the trailing Poincaré wave field and the intensity and duration of the Kelvin-Helmholtz instabilities.

  6. Timber frame walls

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan de Place; Brandt, Erik

    2010-01-01

    A ventilated cavity is usually considered good practice for removing moisture behind the cladding of timber framed walls. Timber frame walls with no cavity are a logical alternative as they are slimmer and less expensive to produce and besides the risk of a two-sided fire behind the cladding....... It was found that the specific damages made to the vapour barrier as part of the test did not have any provable effect on the moisture content. In general elements with an intact vapour barrier did not show a critical moisture content at the wind barrier after four years of exposure....

  7. Low frequency oscillatory flow in a rotating curved pipe

    Institute of Scientific and Technical Information of China (English)

    陈华军; 章本照; 苏霄燕

    2003-01-01

    The low frequency oscillatory flow in a rotating curved pipe was studied by using the method of bi-parameter perturbation. Perturbation solutions up to the second order were obtained and the effects of rotationon the low frequency oscillatory flow were examined in detail, The results indicated that there exists evident difference between the low frequency oscillatory flow in a rotating curved pipe and in a curved pipe without ro-tation. During a period, four secondary vortexes may exist on the circular cross-section and the distribution of axial velocity and wall shear stress are related to the ratio of the Coriolis foree to centrifugal foree and the axial pressure gradient.

  8. Investigation of the interaction of carbon dioxide fluid with internal and external single-wall carbon nanotubes by DFT

    Directory of Open Access Journals (Sweden)

    M. Oftadeh

    2011-07-01

    Full Text Available The effective parameters of (5, 0 and (5, 5 single-wall carbon nanotubes during the interaction with carbon dioxide as sensors are determined. The interaction of carbon dioxide  molecules with internal and external walls of the nanotubes is studied using Gaussian 03 coding by density functional theory (DFT at the B3LYP/6-311G level of theory. CO2 rotation around tube axles vertically and parallel to the internal and external walls has been investigated. The carbon dioxide molecule is predicted to bind only weakly to nanotubes, and the tube-molecule interactions can be identified as physisorption. CO2 adsorption is stronger on external wallsthan on internal walls, and adsorption on the external wall of (5, 0 is stronger than on the external wall of (5, 5; the adsorption energies are exothermic and equal to -0.8884 and -0.0528 kcal/mol, respectively. The rotation energy barrier for (5, 5 is lower than that for (5, 0 in all rotations, therefore in these interactions (5, 5 is more active. The energy gap significantly changes in the presence of  carbon  dioxide molecules on the inside surface of (5, 0 and the electric conductivity is affected, but no remarkable change is observed in the electronic structure of (5, 5.

  9. Extension of the PSE code NOLOT for transition analysis in rotating reference frames

    OpenAIRE

    Dechamps, Xavier; Hein, Stefan

    2016-01-01

    The present work aims at contributing to a better understanding of the effect of rotation on the stability properties of boundary layers. For this purpose, the Parabolized-Stability-Equations based NOLOT code was extended to rotating reference frames through the inclusion of the centrifugal and Coriolis forces. Stability analyses of three flow configurations were then considered for verification: the rotating Blasius Profile, the flow along a curved wall and the three-dimensional flow due to ...

  10. Characteristic time for halo current growth and rotation

    Energy Technology Data Exchange (ETDEWEB)

    Boozer, Allen H., E-mail: ahb17@columbia.edu [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)

    2015-10-15

    A halo current flows for part of its path through the plasma edge and for part through the chamber walls and during tokamak disruptions can be as large as tenths of the plasma current. The primary interest in halo currents is the large force that they can exert on machine components particularly if the toriodal rotation of the halo current resonates with a natural oscillation frequency of the tokamak device. Halo currents arise when required to slow down the growth of a kink that is too unstable to be stabilized by the chamber walls. The width of the current channel in the halo plasma is comparable to the amplitude of the kink, and the halo current grows linearly, not exponentially, in time. The current density in the halo is comparable to that of the main plasma body. The rocket force due to plasma flowing out of the halo and recombining on the chamber walls can cause the non-axisymmetric magnetic structure produced by the kink to rotate toroidally at a speed comparable to the halo speed of sound. Gerhardt's observations of the halo current in NSTX shot 141 687 [Nucl. Fusion 53, 023005 (2013)] illustrate many features of the theory of halo currents and are discussed as a summary of the theory.

  11. A Study of Aerodynamics in Kevlar-Wall Test Sections

    OpenAIRE

    Brown, Kenneth Alexander

    2014-01-01

    This study is undertaken to characterize the aerodynamic behavior of Kevlar-wall test sections and specifically those containing two-dimensional, lifting models. The performance of the Kevlar-wall test section can be evaluated against the standard of the hard-wall test section, which in the case of the Stability Wind Tunnel (SWT) at Virginia Tech can be alternately installed or replaced by the Kevlar-wall test section. As a first step towards the evaluation of the Kevlar-wall test section aer...

  12. Resistive Wall Mode Stability and Control in the Reversed Field Pinch

    International Nuclear Information System (INIS)

    Yadikin, Dmitriy

    2006-03-01

    Control of MHD instabilities using a conducting wall together with external magnetic fields is an important route to improved performance and reliability in fusion devices. Active control of MHD modes is of interest for both the Advanced Tokamak and the Reversed Field Pinch (RFP) configurations. A wide range of unstable, current driven MHD modes is present in the RFP. An ideally conducting wall facing the plasma can in principle provide stabilization to these modes. However, a real, resistive wall characterized by a wall field diffusion time, cannot stabilize the ideal MHD modes unless they rotate with Alfvenic velocity, which is usually not the case. With a resistive wall, the ideal modes are converted into resistive wall modes (RWM) with growth rates comparable to the inverse wall time. Resistive wall modes have been studied in the EXTRAP T2R thin shell RFP device. Growth rates have been measured and found in agreement with linear MHD stability calculations. An advanced system for active control has been developed and installed on the EXTRAP T2R device. The system includes an array of 128 active saddle coils, fully covering the torus surface. Experiments on EXTRAP T2R have for the first time demonstrated simultaneous active suppression of multiple independent RWMs. In experiments with a partial array, coupling of different modes due to the limited number of feedback coils has been observed, in agreement with theory. Different feedback strategies, such as the intelligent shell, the rotating shell, and mode control have been studied. Further, feedback operation with different types of magnetic field sensors, measuring either the radial or the toroidal field components have been compared

  13. Wall locking and multiple nonlinear states of magnetic islands

    International Nuclear Information System (INIS)

    Persson, Mikael; Australian National Univ., Canberra, ACT

    1994-01-01

    The nonlinear evolution of magnetic islands is analysed in configurations with multiple resonant magnetic surfaces. The existence of multiple nonlinear steady states, is discussed. These are shown to be associated with states where the dynamics around the different rational surfaces are coupled or decoupled and in the presence of a wall of finite resistivity may correspond wall-locked or non-wall-locked magnetic islands. For the case of strong wall stabilization the locking is shown to consist of two different phases. During the first phase the locking of the plasma at the different rational surfaces occurs. Only when the outermost resonant magnetic surface has locked to the inner surfaces can the actual wall locking process take place. Consequently, wall locking, of a global mode, involving more than one rational surface, can be prevented by the decoupling of the resonant magnetic surfaces by plasma rotation. Possible implications on tokamak experiments are discussed. (author)

  14. Regional wall thickening in gated myocardial perfusion SPECT in a Japanese population: effect of sex, radiotracer, rotation angles and frame rates

    Energy Technology Data Exchange (ETDEWEB)

    Akhter, Nasima; Nakajima, Kenichi; Okuda, Koichi; Matsuo, Shinro; Yoneyama, Tatsuya; Taki, Junichi; Kinuya, Seigo [Kanazawa University Hospital, Department of Nuclear Medicine, Kanazawa, Ishikawa (Japan)

    2008-09-15

    Gated single-photon emission computed tomography (SPECT) imaging of myocardium by {sup 99m}Tc and {sup 201}Tl is used extensively to measure quantitative cardiac functional parameters. However, factors affecting normal values for myocardial functional parameters and population-specific standards have not yet been established. The aim of the study was to determine the effect of sex, radiotracer, rotation angles and frame rates on resting myocardial wall thickening (WT) and to develop a Japanese standard of normal values for WT. Data from a total of 202 patients with low possibility of having cardiac problems were collected from nine hospitals throughout Japan. Patients were divided into five groups according to study protocol, and WT was evaluated according to the 17-segment and four-region (basal, mid and apical regions and the apex) polar map distribution. WT was generally higher in women than in men irrespective of the use of radiotracers, rotation angles or frame rates, and the difference was highly significant in the mid and apical regions. In any protocol used, resting myocardial thickening in the apex was higher than in the mid and apical regions, and thickening was lowest in the basal region, suggesting heterogeneous regional myocardial thickening (%) in normal subjects. Different rotation angles showed no significant change on WT, but different frame rates and tracers showed significant WT change in both sexes. Percent thickening of the myocardium was significantly higher in imaging by {sup 99m}Tc-labelled tracers than in {sup 201}Tl. Sex, radiotracers and frame rates had a significant effect on myocardial thickening, and the importance of population-specific standards should be emphasized. A normal database can serve as a standard for gated SPECT evaluation of myocardial thickening in a Japanese population and might be applicable to Asian populations having a similar physique. (orig.)

  15. Physical and numerical modelling of earth pressure on anchored sheet pile walls in sand

    DEFF Research Database (Denmark)

    Krogsbøll, Anette Susanne; Fuglsang, Leif D

    2006-01-01

    The influence of wall flexibility on earth pressure, bending moments and failure modes is studied. Numerical models are compared to results from model tests carried out in a geotechnical centrifuge. The back-fill is dry sand and failure is introduced by allowing the wall to rotate around the anchor...

  16. The effect of external boundary conditions on condensation heat transfer in rotating heat pipes

    Science.gov (United States)

    Daniels, T. C.; Williams, R. J.

    1979-01-01

    Experimental evidence shows the importance of external boundary conditions on the overall performance of a rotating heat pipe condenser. Data are presented for the boundary conditions of constant heat flux and constant wall temperature for rotating heat pipes containing either pure vapor or a mixture of vapor and noncondensable gas as working fluid.

  17. Mixed convection of ferrofluids in a lid driven cavity with two rotating cylinders

    Directory of Open Access Journals (Sweden)

    Fatih Selimefendigil

    2015-09-01

    Full Text Available Mixed convection of ferrofluid filled lid driven cavity in the presence of two rotating cylinders were numerically investigated by using the finite element method. The cavity is heated from below, cooled from driven wall and rotating cylinder surfaces and side vertical walls of the cavity are assumed to be adiabatic. A magnetic dipole source is placed below the bottom wall of the cavity. The study is performed for various values of Reynolds numbers (100 ≤ Re ≤ 1000, angular rotational speed of the cylinders (−400 ≤ Ω ≤ 400, magnetic dipole strengths (0 ≤ γ ≤ 500, angular velocity ratios of the cylinders (0.25≤Ωi/Ωj≤4 and diameter ratios of the cylinders (0.5≤Di/Dj≤2. It is observed that flow patterns and thermal transport within the cavity are affected by variation in Reynolds number and magnetic dipole strength. The results of this investigation revealed that cylinder angular velocities, ratio of the angular velocities and diameter ratios have profound effect on heat transfer enhancement within the cavity. Averaged heat transfer enhancements of 181.5 % is achieved for clockwise rotation of the cylinder at Ω = −400 compared to motionless cylinder case. Increasing the angular velocity ratio from Ω2/Ω1=0.25 to Ω2/Ω1=4 brings about 91.7 % of heat transfer enhancement.

  18. Real-Time Rotational Activity Detection in Atrial Fibrillation

    Science.gov (United States)

    Ríos-Muñoz, Gonzalo R.; Arenal, Ángel; Artés-Rodríguez, Antonio

    2018-01-01

    Rotational activations, or spiral waves, are one of the proposed mechanisms for atrial fibrillation (AF) maintenance. We present a system for assessing the presence of rotational activity from intracardiac electrograms (EGMs). Our system is able to operate in real-time with multi-electrode catheters of different topologies in contact with the atrial wall, and it is based on new local activation time (LAT) estimation and rotational activity detection methods. The EGM LAT estimation method is based on the identification of the highest sustained negative slope of unipolar signals. The method is implemented as a linear filter whose output is interpolated on a regular grid to match any catheter topology. Its operation is illustrated on selected signals and compared to the classical Hilbert-Transform-based phase analysis. After the estimation of the LAT on the regular grid, the detection of rotational activity in the atrium is done by a novel method based on the optical flow of the wavefront dynamics, and a rotation pattern match. The methods have been validated using in silico and real AF signals. PMID:29593566

  19. Control of the resistive wall mode with internal coils in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Okabayashi, M.; Bialek, J.; Bondeson, A.; Chance, M.S.; Chu, M.S.; Garofalo, A.M.; Hatcher, R.; In, Y.; Jackson, G.L.; Jayakumar, R.J.; Jensen, T.H.; Katsuro-Hopkins, O.; Haye, R.J. La; Liu, Y.Q.; Navratil, G.A.; Reimerdes, H.; Scoville, J.T.; Strait, E.J.; Takechi, M.; Turnbull, A.D.; Gohil, P.; Kim, J.S.; Makowski, M.A.; Manickam, J.; Menard, J.

    2005-01-01

    Internal coils, 'I-Coils', were installed inside the vacuum vessel of the DIII-D device to generate non-axisymmetric magnetic fields to act directly on the plasma. These fields are predicted to stabilize the resistive wall mode (RWM) branch of the long-wavelength external kink mode with plasma beta close to the ideal wall limit. Feedback using these I-Coils was found to be more effective as compared to using external coils located outside the vacuum vessel. Locating the coils inside the vessel allows for a faster response and the coil geometry also allows for better coupling to the helical mode structure. Initial results were reported previously (Strait E.J. et al 2004 Phys. Plasmas 11 2505). This paper reports on results from extended feedback stabilization operations, achieving plasma parameters up to the regime of C β ∼ 1.0 and open loop growth rates of γ open τ w ∼ 25 where the RWM was predicted to be unstable with only the 'rotational viscous stabilization mechanism'. Here C β ∼ (β - β no-wall.limit )/(β ideal.wall.limit - β no-wall.limit ) is a measure of the beta relative to the stability limits without a wall and with a perfectly conducting wall, and τ w is the resistive flux penetration time of the wall. These feedback experimental results clarified the processes of dynamic error field correction and direct RWM stabilization, both of which took place simultaneously during RWM feedback stabilization operation. MARS-F modelling provides a critical rotation velocity in reasonable agreement with the experiment and predicts that the growth rate increases rapidly as rotation decreases below the critical. The MARS-F code also predicted that for successful RWM magnetic feedback, the characteristic time of the power supply should be limited to a fraction of the growth time of the targeted RWM. The possibility of further improvements in the presently achievable range of operation of feedback gain values is also discussed

  20. Induced motion of domain walls in multiferroics with quadratic interaction

    Energy Technology Data Exchange (ETDEWEB)

    Gerasimchuk, Victor S., E-mail: viktor.gera@gmail.com [National Technical University of Ukraine “Kyiv Polytechnic Institute”, Peremohy Avenue 37, 03056 Kiev (Ukraine); Shitov, Anatoliy A., E-mail: shitov@mail.ru [Donbass National Academy of Civil Engineering, Derzhavina Street 2, 86123 Makeevka, Donetsk Region (Ukraine)

    2013-10-15

    We theoretically study the dynamics of 180-degree domain wall of the ab-type in magnetic materials with quadratic magnetoelectric interaction in external alternating magnetic and electric fields. The features of the oscillatory and translational motions of the domain walls and stripe structures depending on the parameters of external fields and characteristics of the multiferroics are discussed. The possibility of the domain walls drift in a purely electric field is established. - Highlights: • We study DW and stripe DS in multiferroics with quadratic magnetoelectric interaction. • We build up the theory of oscillatory and translational (drift) DW and DS motion. • DW motion can be caused by crossed alternating electric and magnetic fields. • DW motion can be caused by alternating “pure” electric field. • DW drift velocity is formed by the AFM and Dzyaloshinskii interaction terms.

  1. Electro-mechanical coupling of rotating 3D beams

    Directory of Open Access Journals (Sweden)

    Stoykov S.

    2016-01-01

    Full Text Available A rotating thin-walled beam with piezoelectric element is analysed. The beam is considered to vibrate in space, hence the longitudinal, transverse and torsional deformations are taken into account. The bending deformations of the beam are modelled by assuming Timoshenko's theory. Torsion is included by considering that the cross section rotates as a rigid body but can deform in longitudinal direction due to warping. The warping function is computed preliminary by the finite element method. The equation of motion is derived by the principle of virtual work and discretized in space by the Ritz method. Electro-mechanical coupling is included in the model by considering the internal electrical energy and the electric charge output. The piezo-electric constitutive relations are used in reduced form. The beam is assumed to rotate about a fixed axis with constant speed. The equation of motion is derived in rotating coordinate system, but the influence of the rotation of the coordinate system is taken into account through the inertia forces. Results in time domain are presented for different speeds of rotation and frequencies of vibration. The influence of the speed of rotation and of the frequency of vibration on the electrical output is presented and analysed.

  2. Bayesian Alternation During Tactile Augmentation

    Directory of Open Access Journals (Sweden)

    Caspar Mathias Goeke

    2016-10-01

    Full Text Available A large number of studies suggest that the integration of multisensory signals by humans is well described by Bayesian principles. However, there are very few reports about cue combination between a native and an augmented sense. In particular, we asked the question whether adult participants are able to integrate an augmented sensory cue with existing native sensory information. Hence for the purpose of this study we build a tactile augmentation device. Consequently, we compared different hypotheses of how untrained adult participants combine information from a native and an augmented sense. In a two-interval forced choice (2 IFC task, while subjects were blindfolded and seated on a rotating platform, our sensory augmentation device translated information on whole body yaw rotation to tactile stimulation. Three conditions were realized: tactile stimulation only (augmented condition, rotation only (native condition, and both augmented and native information (bimodal condition. Participants had to choose one out of two consecutive rotations with higher angular rotation. For the analysis, we fitted the participants’ responses with a probit model and calculated the just notable difference (JND. Then we compared several models for predicting bimodal from unimodal responses. An objective Bayesian alternation model yielded a better prediction (χred2 = 1.67 than the Bayesian integration model (χred2= 4.34. Slightly higher accuracy showed a non-Bayesian winner takes all model (χred2= 1.64, which either used only native or only augmented values per subject for prediction. However the performance of the Bayesian alternation model could be substantially improved (χred2= 1.09 utilizing subjective weights obtained by a questionnaire. As a result, the subjective Bayesian alternation model predicted bimodal performance most accurately among all tested models. These results suggest that information from augmented and existing sensory modalities in

  3. Boreside rotating ultrasonic tester for wastage determination of LMFBR-type steam generator tubes

    International Nuclear Information System (INIS)

    Neely, H.H.; Renger, H.L.

    1979-01-01

    Large sodium-water reaction (SWR) leak tests are being run in near-prototypic steam generators at prototypic plant conditions of the Liquid Metal Fast Breeder Reactor (LMFBR). These tests simulate various types of steam tube failure at predetermined locations. A SWR results in a highly energetic-exothermic-caustic reaction which erodes neighboring tubes. A boreside-rotating ultrasonic inspection device was developed to measure wall thickness and inside diameter of the 2/one quarter/Cr-1 Mo, 10.1 mm I.D. steam tubes. Rotation of the UT beam yields a complimentary scan of the full tube in a single pass. The UT system was designed with a 15 MHz transducer in pulse-echo compression-wave mode at a pulse rate of 10,000/second. The UT beam is rotated at 20 r/s on a 1.27 mm pitch. System outputs are diameter, wall thickness, attitude, and axial position. Measurements are processed, then fed to a CRT and computer for later retrieval and plotting

  4. Enhanced dielectric-wall linear accelerator

    Science.gov (United States)

    Sampayan, Stephen E.; Caporaso, George J.; Kirbie, Hugh C.

    1998-01-01

    A dielectric-wall linear accelerator is enhanced by a high-voltage, fast e-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

  5. Behaviour of neutrons passing through the Bloch wall

    International Nuclear Information System (INIS)

    Schaerpf, O.

    1976-01-01

    In part I of the present paper the pertinent knowledge about Bloch walls is presented and developed insofar as it appears necessary for the experiments with neutrons, that is to say the direction of magnetization within the domains, the calculation of the variation of magnetization in the wall, the wall thickness, and the zigzag structure of the Bloch wall. In part II it is first clarified why the Bloch wall can be treated as a continuum problem. It shows that this is possible far away from Laue reflexes. For angles far away from Laure-reflex angles the interaction of the periodic structure of the magnetization can be described with the aid of an averaged magnetic flux density. The consequence of it is the possibility of treating the problem by means of a Schroedinger equation with continous interaction. This leads to a law of refraction. The question of the possibilities for explaining the intensity behavior is treated in part III. This part, from different aspects, describes the fact, which already was pointed out in Schaerpf, O., Vehoff, H., Schwink, Ch. 1973, that the spin of the neutrons in passing through the wall is partly taken along by the magnetization gradually rotating in the wall. (orig./WBU) [de

  6. Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

    Science.gov (United States)

    Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

    1998-01-01

    A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

  7. Visualization of the flow in a cylindrical container with a rotating disk

    Science.gov (United States)

    Imahoko, Ryoki; Kurakata, Hiroki; Sakakibara, Jun

    2017-11-01

    We studied a behavior of the flow in a cylindrical container with a rotating disk. The apparatus consists of a fixed cylindrical container of the inner diameter of 140 mm and height H, and a coaxial rotating disc with a diameter of 140 mm connected with a cylindrical shaft driven by an electrical motor. The radial gap between rotating disk and side wall is very slight distance. The height H is variable up to 100 mm. The velocity distribution in the container was measured by means of particle image velocimetry (PIV). The results of this experiments will be discussed at the conference.

  8. Selection of exterior wall using advantageousness comparison; Ulkoseinaen valinta elinkaariedullisuuden perusteella

    Energy Technology Data Exchange (ETDEWEB)

    Saari, A.; Vesa, M.

    2001-07-01

    -economy, the order of the alternatives changes. If the eco-economy is weighted under 20%, the brick wall will be the best alternative, and if weight is between 20 - 90%, the brick-wool-concrete wall is the best. But if it is weighted more than 90%, precast concrete wall is the best. The developed procedure offers a systematic way to estimate the advantageousness of the alternative exterior wall solutions. The results that have been obtained with the presented comparison method are sensitive to the weights of affecting factors the target for the value to be examined. (orig.)

  9. A film-based wall shear stress sensor for wall-bounded turbulent flows

    Science.gov (United States)

    Amili, Omid; Soria, Julio

    2011-07-01

    In wall-bounded turbulent flows, determination of wall shear stress is an important task. The main objective of the present work is to develop a sensor which is capable of measuring surface shear stress over an extended region applicable to wall-bounded turbulent flows. This sensor, as a direct method for measuring wall shear stress, consists of mounting a thin flexible film on the solid surface. The sensor is made of a homogeneous, isotropic, and incompressible material. The geometry and mechanical properties of the film are measured, and particles with the nominal size of 11 μm in diameter are embedded on the film's surface to act as markers. An optical technique is used to measure the film deformation caused by the flow. The film has typically deflection of less than 2% of the material thickness under maximum loading. The sensor sensitivity can be adjusted by changing the thickness of the layer or the shear modulus of the film's material. The paper reports the sensor fabrication, static and dynamic calibration procedure, and its application to a fully developed turbulent channel flow at Reynolds numbers in the range of 90,000-130,000 based on the bulk velocity and channel full height. The results are compared to alternative wall shear stress measurement methods.

  10. Fabrication technology for a series of cylindrical thin-wall cavity targets

    CERN Document Server

    Zheng Yong; Sun Zu Oke; Wang Ming Da; Zhou La; Zhou Zhi Yun

    2002-01-01

    Cylindrical thin-wall cavity targets have been fabricated to study the behavior of superthermal electrons and their effects on inertial confinement fusion (ICF). Self-supporting cavity targets having adjustable, uniform wall thickness, and low surface roughness were required. This required production of high-quality mandrels, coating them by sputtering or electroplating, developing techniques for measurement of wall thickness and other cavity parameters, improving the uniformity of rotation of the mandrels, and preventing damage to the targets during removal from the mandrels. Details of the fabrication process are presented. Experimental results from the use of these targets are presented. These results, in good agreement with simulations, indicate that the use of thin-wall cavity targets is an effective method for studying superthermal electrons in ICF.

  11. Editorial Commentary: A Model for Shoulder Rotator Cuff Repair and for Basic Science Investigations.

    Science.gov (United States)

    Brand, Jefferson C

    2018-04-01

    "Breaking the fourth wall" is a theater convention where the narrator or character speaks directly to the audience. As an Assistant Editor-in-Chief, as I comment on a recent basic science study investigating rotator cuff repair, I break the fourth wall and articulate areas of basic science research excellence that align with the vision that we hold for our journal. Inclusion of a powerful video strengthens the submission. We prefer to publish clinical videos in our companion journal, Arthroscopy Techniques, and encourage basic science video submissions to Arthroscopy. Basic science research requires step-by-tedious-step analogous to climbing a mountain. Establishment of a murine rotator cuff repair model was rigorous and research intensive, biomechanically, radiographically, histologically, and genetically documented, a huge step toward the bone-to-tendon healing research summit. This research results in a model for both rotator cuff repair and the pinnacle of quality, basic science research. Copyright © 2018 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  12. How good a clock is rotation? The stellar rotation-mass-age relationship for old field stars

    International Nuclear Information System (INIS)

    Epstein, Courtney R.; Pinsonneault, Marc H.

    2014-01-01

    The rotation-mass-age relationship offers a promising avenue for measuring the ages of field stars, assuming the attendant uncertainties to this technique can be well characterized. We model stellar angular momentum evolution starting with a rotation distribution from open cluster M37. Our predicted rotation-mass-age relationship shows significant zero-point offsets compared to an alternative angular momentum loss law and published gyrochronology relations. Systematic errors at the 30% level are permitted by current data, highlighting the need for empirical guidance. We identify two fundamental sources of uncertainty that limit the precision of rotation-based ages and quantify their impact. Stars are born with a range of rotation rates, which leads to an age range at fixed rotation period. We find that the inherent ambiguity from the initial conditions is important for all young stars, and remains large for old stars below 0.6 M ☉ . Latitudinal surface differential rotation also introduces a minimum uncertainty into rotation period measurements and, by extension, rotation-based ages. Both models and the data from binary star systems 61 Cyg and α Cen demonstrate that latitudinal differential rotation is the limiting factor for rotation-based age precision among old field stars, inducing uncertainties at the ∼2 Gyr level. We also examine the relationship between variability amplitude, rotation period, and age. Existing ground-based surveys can detect field populations with ages as old as 1-2 Gyr, while space missions can detect stars as old as the Galactic disk. In comparison with other techniques for measuring the ages of lower main sequence stars, including geometric parallax and asteroseismology, rotation-based ages have the potential to be the most precise chronometer for 0.6-1.0 M ☉ stars.

  13. Log-layer mismatch and modeling of the fluctuating wall stress in wall-modeled large-eddy simulations

    Science.gov (United States)

    Yang, Xiang I. A.; Park, George Ilhwan; Moin, Parviz

    2017-10-01

    Log-layer mismatch refers to a chronic problem found in wall-modeled large-eddy simulation (WMLES) or detached-eddy simulation, where the modeled wall-shear stress deviates from the true one by approximately 15 % . Many efforts have been made to resolve this mismatch. The often-used fixes, which are generally ad hoc, include modifying subgrid-scale stress models, adding a stochastic forcing, and moving the LES-wall-model matching location away from the wall. An analysis motivated by the integral wall-model formalism suggests that log-layer mismatch is resolved by the built-in physics-based temporal filtering. In this work we investigate in detail the effects of local filtering on log-layer mismatch. We show that both local temporal filtering and local wall-parallel filtering resolve log-layer mismatch without moving the LES-wall-model matching location away from the wall. Additionally, we look into the momentum balance in the near-wall region to provide an alternative explanation of how LLM occurs, which does not necessarily rely on the numerical-error argument. While filtering resolves log-layer mismatch, the quality of the wall-shear stress fluctuations predicted by WMLES does not improve with our remedy. The wall-shear stress fluctuations are highly underpredicted due to the implied use of LES filtering. However, good agreement can be found when the WMLES data are compared to the direct numerical simulation data filtered at the corresponding WMLES resolutions.

  14. Rotation of an immersed cylinder sliding near a thin elastic coating

    Science.gov (United States)

    Rallabandi, Bhargav; Saintyves, Baudouin; Jules, Theo; Salez, Thomas; Schönecker, Clarissa; Mahadevan, L.; Stone, Howard A.

    2017-07-01

    It is known that an object translating parallel to a soft wall in a viscous fluid produces hydrodynamic stresses that deform the wall, which in turn results in a lift force on the object. Recent experiments with cylinders sliding under gravity near a soft incline, which confirmed theoretical arguments for the lift force, also reported an unexplained steady-state rotation of the cylinders [B. Saintyves et al., Proc. Natl. Acad. Sci. USA 113, 5847 (2016), 10.1073/pnas.1525462113]. Motivated by these observations, we show, in the lubrication limit, that an infinite cylinder that translates in a viscous fluid parallel to a soft wall at constant speed and separation distance must also rotate in order to remain free of torque. Using the Lorentz reciprocal theorem, we show analytically that for small deformations of the elastic layer, the angular velocity of the cylinder scales with the cube of the sliding speed. These predictions are confirmed numerically. We then apply the theory to the gravity-driven motion of a cylinder near a soft incline and find qualitative agreement with the experimental observations, namely, that a softer elastic layer results in a greater angular speed of the cylinder.

  15. Mixed convection heat transfer simulation in a rectangular channel with a variable speed rotational cylinder

    Science.gov (United States)

    Khan, Md Imran; Billah, Md. Mamun; Rahman, Mohammed Mizanur; Hasan, Mohammad Nasim

    2017-12-01

    Numerical simulation of steady two-dimensional heat transfer in a rectangular channel with a centered variable speed cylinder has been performed in this paper. In this setup, an isoflux heater is placed at the bottom wall of the channel while the upper wall is kept isothermal with a low temperature. The cylinder's peripheral speed to maximum inlet fluid velocity ratio (ξ) is varied from 0.5 to 1.5 for both clockwise and anticlockwise rotational cases. Air has been considered as working fluid while other system parameters such as Grashof and Reynolds numbers are varied. The effects of rotational speed, Grashof and Reynolds numbers on the streamline pattern, isothermal lines, local and average Nusselt number are analyzed and presented. It is observed the cylinder's rotational direction and speed has a significant effect on the flow pattern, temperature distribution as well as heat transfer characteristics.

  16. Unsteady laminar flow with convective heat transfer through a rotating curved square duct with small curvature

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Rabindra Nath, E-mail: rnmondal71@yahoo.com; Shaha, Poly Rani [Department of Mathematics, Jagannath University, Dhaka-1100 (Bangladesh); Roy, Titob [Department of Mathematics, Vikarunnesa Nun School and College, Boshundhara, Dhaka (Bangladesh); Yanase, Shinichiro, E-mail: yanase@okayama-u.ac.jp [Department of Mechanical and Systems Engineering, Okayama University, Okayama 700-8530 (Japan)

    2016-07-12

    Unsteady laminar flow with convective heat transfer through a curved square duct rotating at a constant angular velocity about the center of curvature is investigated numerically by using a spectral method, and covering a wide range of the Taylor number −300≤Tr≤1000 for the Dean number Dn = 1000. A temperature difference is applied across the vertical sidewalls for the Grashof number Gr = 100, where the outer wall is heated and the inner wall cooled, the top and bottom walls being adiabatic. Flow characteristics are investigated with the effects of rotational parameter, Tr, and the pressure-driven parameter, Dn, for the constant curvature 0.001. Time evolution calculations as well as their phase spaces show that the unsteady flow undergoes through various flow instabilities in the scenario ‘multi-periodic → chaotic → steady-state → periodic → multi-periodic → chaotic’, if Tr is increased in the positive direction. For negative rotation, however, time evolution calculations show that the flow undergoes in the scenario ‘multi-periodic → periodic → steady-state’, if Tr is increased in the negative direction. Typical contours of secondary flow patterns and temperature profiles are obtained at several values of Tr, and it is found that the unsteady flow consists of two- to six-vortex solutions if the duct rotation is involved. External heating is shown to generate a significant temperature gradient at the outer wall of the duct. This study also shows that there is a strong interaction between the heating-induced buoyancy force and the centrifugal-Coriolis instability in the curved channel that stimulates fluid mixing and consequently enhances heat transfer in the fluid.

  17. Drop deformation and breakup in a partially filled horizontal rotating cylinder

    Science.gov (United States)

    White, Andrew; Pereira, Caroline; Hyacinthe, Hyaquino; Ward, Thomas

    2014-11-01

    Drop deformation and breakup due to shear flow has been studied extensively in Couette devices as well as in gravity-driven flows. In these cases shear is generated either by the moving wall or the drop's motion. For such flows the drop shape remains unperturbed at low capillary number (Ca), deforms at moderate Ca , and can experience breakup as Ca --> 1 and larger. Here single drops of NaOH(aq) will be placed in a horizontal cylindrical rotating tank partially filled with vegetable oil resulting in 10-2 saponification, can yield lower minimum surface tensions and faster adsorption than non-reactive surfactant systems. Oil films between the wall and drop as well as drop shape will be observed as rotation rates and NaOH(aq) concentration are varied. Results will be presented in the context of previous work on bubble and drop shapes and breakup. NSF CBET #1262718.

  18. Stabilization of ideal plasma resistive wall modes in cylindrical geometry: The effect of resistive layers

    International Nuclear Information System (INIS)

    Finn, J.M.

    1995-01-01

    A cylindrical model with finite beta having an external resonant ideal magnetohydrodynamic instability has been constructed. This resonant mode has a mode rational surface, where the safety factor q equals m/n, within the plasma. In this model, the perturbed radial magnetic field for the ideal mode is nonzero between the mode rational surface and the wall, even though it must vanish at the mode rational surface. This property of the mode is in common with the toroidal external kink. Results are presented showing that in the parameter range for which this ideal mode is stable with a conducting wall but unstable with the wall at infinity, a resistive wall mode persists. However, in the presence of plasma resistivity in a resistive layer about the mode rational surface, this resistive wall mode can be stabilized by a plasma rotation frequency of order a nominal resistive instability growth rate. Furthermore, the stabilization occurs in a large gap in wall position or beta. It is also shown that for the ideal resonant mode, as well as resistive plasma modes and nonresonant ideal plasma modes, there is a maximum value of plasma rotation above which there is no stability gap. Discussions are presented suggesting that these properties may hold for the toroidal external kink. copyright 1995 American Institute of Physics

  19. Life stages of wall-bounded decay of Taylor-Couette turbulence

    NARCIS (Netherlands)

    Ostilla-Mónico, Rodolfo; Zhu, Xiaojue; Arza, Vamsi Spandan; Verzicco, Roberto; Lohse, Detlef

    2017-01-01

    The decay of Taylor-Couette turbulence, i.e., the flow between two coaxial and independently rotating cylinders, is numerically studied by instantaneously stopping the forcing from an initially statistically stationary flow field at a Reynolds number of Re=3.5×104. The effect of wall friction is

  20. Towards improved modeling of steel-concrete composite wall elements

    International Nuclear Information System (INIS)

    Vecchio, Frank J.; McQuade, Ian

    2011-01-01

    Highlights: → Improved analysis of double skinned steel concrete composite containment walls. → Smeared rotating crack concept applied in formulation of new analytical model. → Model implemented into finite element program; numerically stable and robust. → Models behavior of shear-critical elements with greater ease and improved accuracy. → Accurate assessments of strength, deformation and failure mode of test specimens. - Abstract: The Disturbed Stress Field Model, a smeared rotating crack model for reinforced concrete based on the Modified Compression Field Theory, is adapted to the analysis of double-skin steel-concrete wall elements. The computational model is then incorporated into a two-dimensional nonlinear finite element analysis algorithm. Verification studies are undertaken by modeling various test specimens, including panel elements subject to uniaxial compression, panel elements subjected to in-plane shear, and wall specimens subjected to reversed cyclic lateral displacements. In all cases, the analysis model is found to provide accurate calculations of structural load capacities, pre- and post-peak displacement responses, post-peak ductility, chronology of damage, and ultimate failure mode. Minor deficiencies are found in regards to the accurate portrayal of faceplate buckling and the effects of interfacial slip between the faceplates and the concrete. Other aspects of the modeling procedure that are in need of further research and development are also identified and discussed.

  1. Reversible Polarization Rotation in Epitaxial Ferroelectric Bilayers

    DEFF Research Database (Denmark)

    Liu, Guangqing; Zhang, Qi; Huang, Hsin-Hui

    2016-01-01

    Polarization rotation engineering is a promising path to giant dielectric and electromechanical responses in ferroelectric materials and devices. This work demonstrates robust and reversible in- to out-of-plane polarization rotation in ultrathin (nanoscale) epitaxial (001) tetragonal PbZr0.3Ti0.7O3...... large-scale polarization rotation switching (≈60 μC cm−2) and an effective d 33 response 500% (≈250 pm V−1) larger than the PZT-R layer alone. Furthermore, this enhancement is stable for more than 107 electrical switching cycles. These bilayers present a simple and highly controllable means to design...... and optimize rotational polar systems as an alternate to traditional composition-based approaches. The precise control of the subtle interface-driven interactions between the lattice and the external factors that control polarization opens a new door to enhanced—or completely new—functional properties....

  2. An alternative mass model for galactic dark coronae

    Directory of Open Access Journals (Sweden)

    Ninković S.

    2001-01-01

    Full Text Available A spherically symmetric mass distribution with two scale parameters for the dark corona of a (spiral galaxy as an alternative to the usually applied quasi-isothermal sphere is considered. Examinations of the rotation curve produced by this distribution over a limited interval of the distance to the rotation axis show that it can be a successful alternative to the usual approximation of the quasiisothermal sphere. This is important taking into account that the potential formula considered in the present paper can be easily generalized towards axial symmetry.

  3. Wall-crossing, Rogers dilogarithm, and the QK/HK correspondence

    CERN Document Server

    Alexandrov, Sergei; Pioline, Boris

    2011-01-01

    When formulated in twistor space, the D-instanton corrected hypermultiplet moduli space in N=2 string vacua and the Coulomb branch of rigid N=2 gauge theories on $R^3 \\times S^1$ are strikingly similar and, to a large extent, dictated by consistency with wall-crossing. We elucidate this similarity by showing that these two spaces are related under a general duality between, on one hand, quaternion-Kahler manifolds with a quaternionic isometry and, on the other hand, hyperkahler manifolds with a rotational isometry, further equipped with a hyperholomorphic circle bundle with a connection. We show that the transition functions of the hyperholomorphic circle bundle relevant for the hypermultiplet moduli space are given by the Rogers dilogarithm function, and that consistency across walls of marginal stability is ensured by the motivic wall-crossing formula of Kontsevich and Soibelman. We illustrate the construction on some simple examples of wall-crossing related to cluster algebras for rank 2 Dynkin quivers. In...

  4. General thermo-elastic solution of radially heterogeneous, spherically isotropic rotating sphere

    Energy Technology Data Exchange (ETDEWEB)

    Bayat, Yahya; EkhteraeiToussi, THamid [Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

    2015-06-15

    A thick walled rotating spherical object made of transversely isotropic functionally graded materials (FGMs) with general types of thermo-mechanical boundary conditions is studied. The thermo-mechanical governing equations consisting of decoupled thermal and mechanical equations are represented. The centrifugal body forces of the rotation are considered in the modeling phase. The unsymmetrical thermo-mechanical boundary conditions and rotational body forces are expressed in terms of the Legendre series. The series method is also implemented in the solution of the resulting equations. The solutions are checked with the known literature and FEM based solutions of ABAQUS software. The effects of anisotropy and heterogeneity are studied through the case studies and the results are represented in different figures. The newly developed series form solution is applicable to the rotating FGM spherical transversely isotropic vessels having nonsymmetrical thermo-mechanical boundary condition.

  5. Electromagnetic forces on type-II superconducting rotating cylinders

    International Nuclear Information System (INIS)

    Saif, A.G.; Refai, T.F.; El-Sabagh, M.A.

    1995-01-01

    Analytical solutions of the electromagnetic fields are presented for a system composed of an infinitely long superconducting cylinder rotating about its axis and placed parallel to two infinitely long normal conducting wires. Both wires carry the same alternating current. From the obtained electromagnetic fields the electromagnetic power loss on the cylinder surface, electromagnetic forces due to induced currents, electromagnetic torque, and the work opposing the rotation of the cylinder are calculated. (orig.)

  6. SUBSTANTIATION OF DESIGN MEASURES TO INCREASE ENERGY EFFICIENCY OF EXTERIOR WALLS

    Directory of Open Access Journals (Sweden)

    Musorina Tat'yana Aleksandrovna

    2017-11-01

    Full Text Available Subject: multi-layer building envelope is the subject of the paper. Recently, in the context of energy conservation policies, the heat engineering requirements for enveloping structures of buildings and structures have significantly increased. At the same time, their moisture condition has a significant impact on the operational properties of materials of structures and on microclimate of rooms constrained by these structures. Research objectives: emphasize importance of the task of predicting the temperature and moisture condition of the walling at the stage of design and construction of building envelopes. In this paper, the temperature distributions in layered walls are analyzed. Materials and methods: to achieve the objectives, computational and experimental studies are conducted. By alternating (rearranging layers and preserving the thermal resistance of the wall on the whole, we find the optimal alternation of layers that minimizes deviation of the maximum wall temperature from the average temperature. Results: for the optimal location of layers in the wall’s structure, the moisture penetration into the wall is minimal or absent altogether. This is possible if the heat-insulating layer is mounted on the outer surface of the structure. Conclusions: the obtained results of computational and experimental studies allow us to verify appropriateness of accounting for alternation of layers in multilayer structures. These calculations proved that the higher the average temperature level, the more energy-efficient the structure will be.

  7. Development of an ECT technique for discriminating between a through-wall/non through-wall crack in a steam generator tube

    International Nuclear Information System (INIS)

    Lee, D.H.; Choi, M.S.; Hur, D.H.; Han, J.H.; Lee, U.C.

    2004-01-01

    In a lot of pressurized water reactors, PWSCC (primary water stress corrosion cracking) has been observed in the expansion or u-bend transitions of the alloy 600 steam generator tubes. Particularly, the development of a through-wall crack may cause leakage of the primary coolant during operation and the resultant forced outage, and the in-situ pressure test has often been used to evaluate the integrity and the leakage of the cracked tube during an in-service inspection. However, this process requires additional equipment and hours, and the tested tubes are plugged due to the plastic deformation induced by the internal pressurization. This paper describes a new evaluation technique of the Eddy current test, by which it can be determined whether the crack is through-wall or non through-wall. The technique is based upon the analysis of the characteristics in the Eddy current signals from the crack and also includes the method of measuring exact through-wall length of the crack. The proof and applicability of the technique is discussed with the results of the destructive tests on cracked tubes extracted from a commercial power plant. Also, the effect of crack opening, which reflects the driving force for a crack propagation of non through-wall crack and the leak rate of a through-wall crack, upon the characteristics of the Eddy current signals from the coils of the motorized rotating probe is investigated and discussed using steam generator tube samples with manufactured axial cracks of a through-wall and non through-wall. (orig.)

  8. Seismic behavior of semi-supported steel shear walls

    DEFF Research Database (Denmark)

    Jahanpour, A.; Jönsson, J.; Moharrami, H.

    2012-01-01

    During the recent past decade semi-supported steel shear walls (SSSW) have been introduced as an alternative to the traditional type of steel plate shear walls. In this system the shear wall does not connect directly to the main columns of the building frame; instead it is connected to a pair...... of secondary columns that do not carry vertical gravity loads. In this paper, the interaction between the wall plate and the surrounding frame is investigated experimentally for typical SSSW systems in which the wall-frame has a bending-dominant behavior. Based on the possible storey failure mechanisms...... a simple method is proposed for design of the floor beams. A quasi static cyclic experimental study has been performed in order to investigate the collapse behavior of the wall-plate and surrounding frame. Furthermore the test setup has been developed in order to facilitate standardized cyclic tests...

  9. Liquid metal flow in a finite-length cylinder with a rotating magnetic field

    International Nuclear Information System (INIS)

    Gelfgat, Yu.M.; Gorbunov, L.A.; Kolevzon, V.

    1993-01-01

    A liquid metal flow induced by a rotating magnetic field in a cylindrical container of finite height was investigated experimentally. It was demonstrated that the flow in a rotating magnetic field is similar to geophysical flows: the fluid rotates uniformly with depth and the Ekman layer exists at the container bottom. Near the vertical wall the flow is depicted in the form of a confined jet whose thickness determines the instability onset in a rotating magnetic field. It was shown that the critical Reynolds number can be found by using the jet velocity u 0 for Re cr =u 2 0 /ν∂u/∂r. The effect of frequency of a magnetic field on the fluid flow was also studied. An approximate theoretical model is presented for describing the fluid flow in a uniform rotating magnetic field. (orig.)

  10. Using digital holographic microscopy for simultaneous measurements of 3D near wall velocity and wall shear stress in a turbulent boundary layer

    Science.gov (United States)

    Sheng, J.; Malkiel, E.; Katz, J.

    2008-12-01

    A digital holographic microscope is used to simultaneously measure the instantaneous 3D flow structure in the inner part of a turbulent boundary layer over a smooth wall, and the spatial distribution of wall shear stresses. The measurements are performed in a fully developed turbulent channel flow within square duct, at a moderately high Reynolds number. The sample volume size is 90 × 145 × 90 wall units, and the spatial resolution of the measurements is 3 8 wall units in streamwise and spanwise directions and one wall unit in the wall-normal direction. The paper describes the data acquisition and analysis procedures, including the particle tracking method and associated method for matching of particle pairs. The uncertainty in velocity is estimated to be better than 1 mm/s, less than 0.05% of the free stream velocity, by comparing the statistics of the normalized velocity divergence to divergence obtained by randomly adding an error of 1 mm/s to the data. Spatial distributions of wall shear stresses are approximated with the least square fit of velocity measurements in the viscous sublayer. Mean flow profiles and statistics of velocity fluctuations agree very well with expectations. Joint probability density distributions of instantaneous spanwise and streamwise wall shear stresses demonstrate the significance of near-wall coherent structures. The near wall 3D flow structures are classified into three groups, the first containing a pair of counter-rotating, quasi streamwise vortices and high streak-like shear stresses; the second group is characterized by multiple streamwise vortices and little variations in wall stress; and the third group has no buffer layer structures.

  11. Contributions of the wall boundary layer to the formation of the counter-rotating vortex pair in transverse jets

    KAUST Repository

    SCHLEGEL, FABRICE; WEE, DAEHYUN; MARZOUK, YOUSSEF M.; GHONIEM, AHMED F.

    2011-01-01

    generation along the channel wall, captures unsteady interactions between the wall boundary layer and the jet - in particular, the separation of the wall boundary layer and its transport into the interior. For comparison, we also implement a reduced boundary

  12. Black hole vacua and rotation

    International Nuclear Information System (INIS)

    Krishnan, Chethan

    2011-01-01

    Recent developments suggest that the near-region of rotating black holes behaves like a CFT. To understand this better, I propose to study quantum fields in this region. An instructive approach for this might be to put a large black hole in AdS and to think of the entire geometry as a toy model for the 'near-region'. Quantum field theory on rotating black holes in AdS can be well-defined (unlike in flat space), if fields are quantized in the co-rotating-with-the-horizon frame. First, some generalities of constructing Hartle-Hawking Green functions in this approach are discussed. Then as a specific example where the details are easy to handle, I turn to 2+1 dimensions (BTZ), write down the Green functions explicitly starting with the co-rotating frame, and observe some structural similarities they have with the Kerr-CFT scattering amplitudes. Finally, in BTZ, there is also an alternate construction for the Green functions: we can start from the covering AdS 3 space and use the method of images. Using a 19th century integral formula, I show the equality between the boundary correlators arising via the two constructions.

  13. Controlling the number of walls in multi walled carbon nanotubes/alumina hybrid compound via ball milling of precipitate catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Nosbi, Norlin [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia); Akil, Hazizan Md, E-mail: hazizan@usm.my [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia); Cluster for Polymer Composite (CPC), Science and Engineering Research Centre, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia)

    2015-06-15

    Graphical abstract: - Highlights: • We report that, to manipulate carbon nanotubes geometry and number of walls are by controlling the precipitate catalyst size. • Number of walls and geometry effects depend on the milling time of the precipitate catalyst. • Increasing milling of time will decrease the carbon nanotubes number of walls. • Increasing milling of time will increase the carbon nanotubes thermal conductivity. - Abstract: This paper reports the influence of milling time on the structure and properties of the precipitate catalyst of multi walled carbon nanotubes (MWCNT)/alumina hybrid compound, produced through the chemical vapour deposition (CVD) process. For this purpose, light green precipitate consisted of aluminium, nickel(II) nitrate hexahydrate and sodium hydroxide mixture was placed in a planetary mill equipped with alumina vials using alumina balls at 300 rpm rotation speed for various milling time (5–15 h) prior to calcinations and CVD process. The compound was characterized using various techniques. Based on high-resolution transmission electron microscopy analysis, increasing the milling time up to 15 h decreased the diameter of MWCNT from 32.3 to 13.1 nm. It was noticed that the milling time had a significant effect on MWCNT wall thickness, whereby increasing the milling time from 0 to 15 h reduced the number of walls from 29 to 12. It was also interesting to note that the carbon content increased from 23.29 wt.% to 36.37 wt.% with increasing milling time.

  14. The annihilation of vertical-Bloch lines in the walls of hard domains to which bias fields and in-plane fields are alternately applied

    International Nuclear Information System (INIS)

    Sun, H.Y.; Hu, H.N.; Nie, X.F.

    2001-01-01

    The annihilation of vertical-Bloch lines in magnetic domain walls of the ordinary hard bubbles, to which both bias fields and in-plane fields are alternately applied, is investigated experimentally. The influence of an in-plane magnetic field on ordinary hard bubbles (OHB), dumbbell domains of the first kind (ID), and dumbbell domains of the second kind (IID) was analyzed, and a critical in-plane field range [H ip 0 ,H ip 2 ] for vertical Bloch line (VBL) annihilation was found. For the three types of hard domains (H ip 0 is the minimum critical in-plane field of VBLs which begin to be unstable, H ip 2 is the minimum critical in-plane field which only needs to be applied one time for collapse of all OHBs), the critical field range is the same with H ip 0 ≅8πM s . We hypothesize that there exists a direction along which the vertical-Bloch lines in the domain walls are annihilated most easily. It is also observed that the stability of vertical-Bloch lines in the domain walls does not depend on the initial state. This provides a more detailed description of the minimum critical in-plane field than previously known

  15. Large eddy simulation of spanwise rotating turbulent channel flow with dynamic variants of eddy viscosity model

    Science.gov (United States)

    Jiang, Zhou; Xia, Zhenhua; Shi, Yipeng; Chen, Shiyi

    2018-04-01

    A fully developed spanwise rotating turbulent channel flow has been numerically investigated utilizing large-eddy simulation. Our focus is to assess the performances of the dynamic variants of eddy viscosity models, including dynamic Vreman's model (DVM), dynamic wall adapting local eddy viscosity (DWALE) model, dynamic σ (Dσ ) model, and the dynamic volumetric strain-stretching (DVSS) model, in this canonical flow. The results with dynamic Smagorinsky model (DSM) and direct numerical simulations (DNS) are used as references. Our results show that the DVM has a wrong asymptotic behavior in the near wall region, while the other three models can correctly predict it. In the high rotation case, the DWALE can get reliable mean velocity profile, but the turbulence intensities in the wall-normal and spanwise directions show clear deviations from DNS data. DVSS exhibits poor predictions on both the mean velocity profile and turbulence intensities. In all three cases, Dσ performs the best.

  16. Trapping of oxygen vacancies on twin walls of CaTiO3: a computer simulation study

    International Nuclear Information System (INIS)

    Calleja, Mark; Dove, Martin T; Salje, Ekhard K H

    2003-01-01

    We have studied the atomic structure of [001] 90 deg. rotation twin walls in orthorhombic CaTiO 3 (symmetry Pbnm) at low temperature (10 K) and their effects on oxygen vacancies. The wall thickness was found to be 2.3 nm at T || T c and it was found that it is energetically favourable for such vacancies to reside in the wall, particularly when bridging titania ions in the (001) plane. The binding energy of an oxygen vacancy in the wall with respect to the bulk is calculated to be ≤ 1.2 eV

  17. Control of the Resistive Wall Mode in Advanced Tokamak Plasmas on DIII-D

    International Nuclear Information System (INIS)

    Garofalo, A.M.; Strait, E.J.; Bialek, J.; Frederickson, E.; Gryaznevich, M.; Jensen, T.H.; Johnson, L.C.; La Haye, R.J.; Navratil, G.A.; Lazarus, E.A.; Luce, T.C.; Makowski, M.; Okabayashi, M.; Rice, B.W.; Scoville, J.T.; Turnbull, A.D.; Walker, M.L.

    1999-01-01

    Resistive wall mode (RWM) instabilities are found to be a limiting factor in advanced tokamak (AT) regimes with low internal inductance. Even small amplitude modes can affect the rotation profile and the performance of these ELMing H-mode discharges. Although complete stabilization of the RWM by plasma rotation has not yet been observed, several discharges with increased beam momentum and power injection sustained good steady-state performance for record time extents. The first investigation of active feedback control of the RWM has shown promising results: the leakage of the radial magnetic flux through the resistive wall can be successfully controlled, and the duration of the high beta phase can be prolonged. The results provide a comparative test of several approaches to active feedback control, and are being used to benchmark the analysis and computational models of active control

  18. Experiments on barotropic vortex-wall interaction on a topographic β plane

    NARCIS (Netherlands)

    Zavala Sansón, L.; Heijst, van G.J.F.; Janssen, F.J.J.G.

    1999-01-01

    The problem of a barotropic cyclonic vortex, moving on a ß plane and interacting with a meridional vertical wall, is studied by means of laboratory experiments and a finite difference numerical model. In the laboratory, the vortex is produced in a rectangular rotating tank with a weakly sloping

  19. The method to design the length of thin-wall flexible rotor

    International Nuclear Information System (INIS)

    Zhang Yue; Yao Zengzhong; Baigu Lafu

    2014-01-01

    Thin-wall flexible rotor is frequently used in rotating machinery. For this rotor the vibration is very complex under the working speed. So the composition design is very difficult. In this paper, for a thin-wall flexible rotor, the material and rotor diameter are determined from spatial structure, the working speed is determined from strength of the material, the first bending critical speed is determined from working speed, then the influence of length on the critical speed is researched. According to the influence of critical speed on the vibration, the length design method is researched, the design steps and methods are given, the safety margin of vibration is analysed. Design validity is established by test. The method is generally suitable for thin-wall flexible rotor. (authors)

  20. Vibrational Suspension of Light Sphere in a Tilted Rotating Cylinder with Liquid

    Directory of Open Access Journals (Sweden)

    Victor G. Kozlov

    2014-01-01

    Full Text Available The dynamics of a light sphere in a quickly rotating inclined cylinder filled with liquid under transversal vibrations is experimentally investigated. Due to inertial oscillations of the sphere relative to the cavity, its rotation velocity differs from the cavity one. The intensification of the lagging motion of a sphere and the excitation of the outstripping differential rotation are possible under vibrations. It occurs in the resonant areas where the frequency of vibrations coincides with the fundamental frequency of the system. The position of the sphere in the center of the cylinder could be unstable. Different velocities of the sphere are matched with its various quasistationary positions on the axis of rotating cavity. In tilted rotating cylinder, the axial component of the gravity force appears; however, the light sphere does not float to the upper end wall but gets the stable position at a definite distance from it. It makes possible to provide a vibrational suspension of the light sphere in filled with liquid cavity rotating around the vertical axis. It is found that in the wide range of the cavity inclination angles the sphere position is determined by the dimensionless velocity of body differential rotation.

  1. A computer controlled ultrasonic measurement and testequipment for rotation-symmetrical products

    International Nuclear Information System (INIS)

    Abend, K.; Lang, R.; Schmidt, U.; Schuett, U.; Sterberg, W.

    1976-01-01

    During production of rotation-symmetrical thin wall precision tubes, dimensions must be measured and the tubes have to be inspected for surface defects. Within the production area of the tubes, several measurement points for different applications are located at different places. The paper describes their on-line connection to a process-computer system

  2. Stokes flow heat transfer in an annular, rotating heat exchanger

    International Nuclear Information System (INIS)

    Saatdjian, E.; Rodrigo, A.J.S.; Mota, J.P.B.

    2011-01-01

    The heat transfer rate into highly viscous, low thermal-conductivity fluids can be enhanced significantly by chaotic advection in three-dimensional flows dominated by viscous forces. The physical effect of chaotic advection is to render the cross-sectional temperature field uniform, thus increasing both the wall temperature gradient and the heat flux into the fluid. A method of analysis for one such flow-the flow in the eccentric, annular, rotating heat exchanger-and a procedure to determine the best heat transfer conditions, namely the optimal values of the eccentricity ratio and time-periodic rotating protocol, are discussed. It is shown that in continuous flows, such as the one under consideration, there exists an optimum frequency of the rotation protocol for which the heat transfer rate is a maximum. - Highlights: → The eccentric, annular, rotating heat exchanger is studied for periodic Stokes flow. → Counter-rotating the inner tube with a periodic velocity enhances the heat transfer. → The heat-transfer enhancement under such conditions is due to chaotic advection. → For a given axial flow rate there is a frequency that maximizes the heat transfer. → There is also an optimum value of the eccentricity ratio.

  3. Lymphocyte trafficking and HIV infection of human lymphoid tissue in a rotating wall vessel bioreactor

    Science.gov (United States)

    Margolis, L. B.; Fitzgerald, W.; Glushakova, S.; Hatfill, S.; Amichay, N.; Baibakov, B.; Zimmerberg, J.

    1997-01-01

    The pathogenesis of HIV infection involves a complex interplay between both the infected and noninfected cells of human lymphoid tissue, the release of free viral particles, the de novo infection of cells, and the recirculatory trafficking of peripheral blood lymphocytes. To develop an in vitro model for studying these various aspects of HIV pathogenesis we have utilized blocks of surgically excised human tonsils and a rotating wall vessel (RWV) cell culture system. Here we show that (1) fragments of the surgically excised human lymphoid tissue remain viable and retain their gross cytoarchitecture for at least 3 weeks when cultured in the RWV system; (2) such lymphoid tissue gradually shows a loss of both T and B cells to the surrounding growth medium; however, this cellular migration is reversible as demonstrated by repopulation of the tissue by labeled cells from the growth medium; (3) this cellular migration may be partially or completely inhibited by embedding the blocks of lymphoid tissue in either a collagen or agarose gel matrix; these embedded tissue blocks retain most of the basic elements of a normal lymphoid cytoarchitecture; and (4) both embedded and nonembedded RWV-cultured blocks of human lymphoid tissue are capable of productive infection by HIV-1 of at least three various strains of different tropism and phenotype, as shown by an increase in both p24 antigen levels and free virus in the culture medium, and by the demonstration of HIV-1 RNA-positive cells inside the tissue identified by in situ hybridization. It is therefore reasonable to suggest that gel-embedded and nonembedded blocks of human lymphoid tissue, cocultured with a suspension of tonsillar lymphocytes in an RWV culture system, constitute a useful model for simulating normal lymphocyte recirculatory traffic and provide a new tool for testing the various aspects of HIV pathogenesis.

  4. Nonlinear analysis of composite thin-walled helicopter blades

    Science.gov (United States)

    Kalfon, J. P.; Rand, O.

    Nonlinear theoretical modeling of laminated thin-walled composite helicopter rotor blades is presented. The derivation is based on nonlinear geometry with a detailed treatment of the body loads in the axial direction which are induced by the rotation. While the in-plane warping is neglected, a three-dimensional generic out-of-plane warping distribution is included. The formulation may also handle varying thicknesses and mass distribution along the cross-sectional walls. The problem is solved by successive iterations in which a system of equations is constructed and solved for each cross-section. In this method, the differential equations in the spanwise directions are formulated and solved using a finite-differences scheme which allows simple adaptation of the spanwise discretization mesh during iterations.

  5. Active control of multiple resistive wall modes

    International Nuclear Information System (INIS)

    Brunsell, P. R.; Yadikin, D.; Gregoratto, D.; Paccagnella, R.; Liu, Y. Q.; Bolzonella, T.; Cecconello, M.; Drake, J. R.; Kuldkepp, M.; Manduchi, G.; Marchiori, G.; Marrelli, L.; Partin, P.; Menmuir, S.; Ortolani, S.; Rachlew, E.; Spizzo, S.; Zanca, P.

    2005-01-01

    Active magnetic feedback suppression of resistive wall modes is of common interest for several fusion concepts relying on close conducting walls for stabilization of ideal magnetohydrodynamic (MHD) modes. In the advanced tokamak without plasma rotation the kink mode is not completely stabilized, but rather converted into an unstable resistive wall mode (RWM) with a growth time comparable to the wall magnetic flux penetration time. The reversed field pinch (RFP) is similar to the advanced tokamak in the sense that it uses a conducting wall for kink mode stabilization. Also both configurations are susceptible to resonant field error amplification of marginally stable modes. However, the RFP has a different RWM spectrum and, in general, a range of modes is unstable. Hence, the requirement for simultaneous feedback stabilization of multiple independent RWMs arises for the RFP configuration. Recent experiments on RWM feedback stabilization, performed in the RFP device EXTRAP T2R [1], are presented. The experimental results obtained are the first demonstration of simultaneous feedback control of multiple independent RWMs [2]. Using an array of active magnetic coils, a reproducible suppression of several RWMs is achieved for the duration of the discharge, 3-5 wall times, through feedback action. An array with 64 active saddle coils at 4 poloidal times 16 toroidal positions is used. The important issues of side band generation by the active coil array and the accompanying coupling of different unstable modes through the feedback action are addressed in this study. Open loop control experiments have been carried out to quantitatively study resonant field error amplification. (Author)

  6. Microfluidics with fluid walls.

    Science.gov (United States)

    Walsh, Edmond J; Feuerborn, Alexander; Wheeler, James H R; Tan, Ann Na; Durham, William M; Foster, Kevin R; Cook, Peter R

    2017-10-10

    Microfluidics has great potential, but the complexity of fabricating and operating devices has limited its use. Here we describe a method - Freestyle Fluidics - that overcomes many key limitations. In this method, liquids are confined by fluid (not solid) walls. Aqueous circuits with any 2D shape are printed in seconds on plastic or glass Petri dishes; then, interfacial forces pin liquids to substrates, and overlaying an immiscible liquid prevents evaporation. Confining fluid walls are pliant and resilient; they self-heal when liquids are pipetted through them. We drive flow through a wide range of circuits passively by manipulating surface tension and hydrostatic pressure, and actively using external pumps. Finally, we validate the technology with two challenging applications - triggering an inflammatory response in human cells and chemotaxis in bacterial biofilms. This approach provides a powerful and versatile alternative to traditional microfluidics.The complexity of fabricating and operating microfluidic devices limits their use. Walsh et al. describe a method in which circuits are printed as quickly and simply as writing with a pen, and liquids in them are confined by fluid instead of solid walls.

  7. Inertial wave beams and inertial wave modes in a rotating cylinder with time-modulated rotation rate

    Science.gov (United States)

    Borcia, Ion D.; Ghasemi V., Abouzar; Harlander, Uwe

    2014-05-01

    shift towards higher frequencies. This frequency shift is due to the reduction of the effective resonance volume that results from the existence of a Stokes boundary layer at the outer librating wall. Due to the symmetry of the forcing not all possible modes can be excited. It is shown that only symmetric modes with respect to the rotation axis exist. From a fundamental perspective, the study might help to understand better inertial mode excitation in librating planets and moons where inertial waves are emitted from critical points on the inner or outer spherical boundary. Recently, Zhang et al. (2013) pointed out the resonance should not occur in symmetric librating bodies without precession. We will discuss how this assumption depends on the boundary conditions. It might turn out that even when the projection of the Euler (or Poincare) force on the modes is zero, the projection of the excited wave beams on the modes is non-zero. K. Zhang, K. H. Chan, X. Liao, and J. M. Aurnou. The non-resonant response of fluid in a rapidly rotating sphere undergoing longitudinal libration, J. Fluid Mech.,720, 212-235, 2013. I. D. Borcia and U. Harlander. Inertial waves in a rotating annulus with inclined inner cylinder, Theoret. Comp. Fluid Dynamics, 27, 397-413, 2013. I. D. Borcia, A. Ghasemi V., and U. Harlander. Inertial wave mode excitation inside a rotating cylindrical container with librating walls, submitted to Fluid Dyn. Res.,2013. M. Klein, T. Seelig, M. V. Kurgansky, A. Ghasemi V., I. D. Borcia, A. Will, E. Schaller, C. Egbers, and Uwe Harlander. Inertial wave excitation and focusing in a liquid bounded by a frustum and a cylinder, submitted to J. Fluid Mech., 2013.

  8. Sibling cycle piston and valving method

    Science.gov (United States)

    Mitchell, Matthew P. (Inventor); Bauwens, Luc (Inventor)

    1990-01-01

    A double-acting, rotating piston reciprocating in a cylinder with the motion of the piston providing the valving action of the Sibling Cycle through the medium of passages between the piston and cylinder wall. The rotating piston contains regenerators ported to the walls of the piston. The piston fits closely in the cylinder at each end of the cylinder except in areas where the wall of the cylinder is relieved to provide passages between the cylinder wall and the piston leading to the expansion and compression spaces, respectively. The piston reciprocates as it rotates. The cylinder and piston together comprise an integral valve that seqentially opens and closes the ports at the ends of the regenerators alternately allowing them to communicate with the expansion space and compression space and blocking that communication. The relieved passages in the cylinder and the ports in the piston are so arranged that each regenerator is sequentially (1) charged with compressed working gas from the compression space; (2) isolated from both expansion and compression spaces; (3) discharged of working gas into the expansion space; and (4) simultaneously charged with working gas from the expansion space while being discharged of working gas into the compression space, in the manner of the Sibling Cycle. In an alterate embodiment, heat exchangers are external to the cylinder and ports in the cylinder wall are alternately closed by the wall of the piston and opened to the expansion and compression spaces through relieved passages in the wall of the reciprocating, rotating piston.

  9. Kinetic-contact-driven gigantic energy transfer in a two-dimensional Lennard-Jones fluid confined to a rotating pore

    Science.gov (United States)

    Karbowniczek, Paweł; Chrzanowska, Agnieszka

    2017-11-01

    A two-dimensional Lennard-Jones system in a circular and rotating container has been studied by means of molecular dynamics technique. A nonequilibrium transition to the rotating stage has been detected in a delayed time since an instant switching of the frame rotation. This transition is attributed to the increase of the density at the wall because of the centrifugal force. At the same time the phase transition occurs, the inner system changes its configuration of the solid-state type into the liquid type. Impact of angular frequency and molecular roughness on the transport properties of the nonrotating and rotating systems is analyzed.

  10. The effect and contribution of wind generated rotation on outlet temperature and heat gain of LS-2 parabolic trough solar collector

    Directory of Open Access Journals (Sweden)

    Sadaghiyani Omid Karimi

    2013-01-01

    Full Text Available The Monte Carlo ray tracing method is applied and coupled with finite volume numerical methods to study effect of rotation on outlet temperature and heat gain of LS-2 parabolic trough concentrator (PTC. Based on effect of sunshape, curve of mirror and use of MCRT, heat flux distribution around of inner wall of evacuated tube is calculated. After calculation of heat flux, the geometry of LS-2 Luz collector is created and finite volume method is applied to simulate. The obtained results are compared with Dudley et al test results for irrotational cases to validate these numerical solving models. Consider that, for rotational models ,the solving method separately with K.S. Ball's results. In this work, according to the structure of mentioned collector, we use plug as a flow restriction. In the rotational case studies, the inner wall rotates with different angular speeds. We compare results of rotational collector with irrotational. Also for these two main states, the location of plug changed then outlet temperature and heat gain of collector are studied. The results show that rotation have positive role on heat transfer processing and the rotational plug in bottom half of tube have better effectual than upper half of tube. Also the contribution of rotation is calculated in the all of case studies. Working fluid of these study is one of the oil derivatives namely Syltherm-800. The power of wind can be used to rotate tube of collector.

  11. Influence of Non-linear Radiation Heat Flux on Rotating Maxwell Fluid over a Deformable Surface: A Numerical Study

    Science.gov (United States)

    Mustafa, M.; Mushtaq, A.; Hayat, T.; Alsaedi, A.

    2018-04-01

    Mathematical model for Maxwell fluid flow in rotating frame induced by an isothermal stretching wall is explored numerically. Scale analysis based boundary layer approximations are applied to simplify the conservation relations which are later converted to similar forms via appropriate substitutions. A numerical approach is utilized to derive similarity solutions for broad range of Deborah number. The results predict that velocity distributions are inversely proportional to the stress relaxation time. This outcome is different from that observed for the elastic parameter of second grade fluid. Unlike non-rotating frame, the solution curves are oscillatory decaying functions of similarity variable. As angular velocity enlarges, temperature rises and significant drop in the heat transfer coefficient occurs. We note that the wall slope of temperature has an asymptotically decaying profile against the wall to ambient ratio parameter. From the qualitative view point, temperature ratio parameter and radiation parameter have similar effect on the thermal boundary layer. Furthermore, radiation parameter has a definite role in improving the cooling process of the stretching boundary. A comparative study of current numerical computations and those from the existing studies is also presented in a limiting case. To our knowledge, the phenomenon of non-linear radiation in rotating viscoelastic flow due to linearly stretched plate is just modeled here.

  12. Repair of chest wall defects after irradiation for breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, L E

    1976-03-01

    A simple technique using a contralateral deltopectoral flap is described for the immediate repair of defects of the chest wall resulting from excision of radionecrosis or persistent tumour after radiotherapy. Successful use in 3 consecutive cases has shown that the deltopectoral flap may be rotated through a full 180/sup 0/ without compromise of blood supply and that primary healing may be obtained.

  13. One-dimensional in-plane edge domain walls in ultrathin ferromagnetic films

    Science.gov (United States)

    Lund, Ross G.; Muratov, Cyrill B.; Slastikov, Valeriy V.

    2018-03-01

    We study existence and properties of 1D edge domain walls in ultrathin ferromagnetic films with uniaxial in-plane magnetic anisotropy. In these materials, the magnetization vector is constrained to lie entirely in the film plane, with the preferred directions dictated by the magnetocrystalline easy axis. We consider magnetization profiles in the vicinity of a straight film edge oriented at an arbitrary angle with respect to the easy axis. To minimize the micromagnetic energy, these profiles form transition layers in which the magnetization vector rotates away from the direction of the easy axis to align with the film edge. We prove existence of edge domain walls as minimizers of the appropriate 1D micromagnetic energy functional and show that they are classical solutions of the associated Euler-Lagrange equation with a Dirichlet boundary condition at the edge. We also perform a numerical study of these 1D domain walls and uncover further properties of these domain wall profiles.

  14. Specific labeling of peptidoglycan precursors as a tool for bacterial cell wall studies

    NARCIS (Netherlands)

    van Dam, V.; Olrichs, N.K.; Breukink, E.J.

    2009-01-01

    Wall chart: The predominant component of the bacterial cell wall, peptidoglycan, consists of long alternating stretches of aminosugar subunits interlinked in a large three-dimensional network and is formed from precursors through several cytosolic and membrane-bound steps. The high tolerance of the

  15. Domain walls in single-chain magnets

    Science.gov (United States)

    Pianet, Vivien; Urdampilleta, Matias; Colin, Thierry; Clérac, Rodolphe; Coulon, Claude

    2017-12-01

    The topology and creation energy of domain walls in different magnetic chains (called Single-Chain Magnets or SCMs) are discussed. As these domain walls, that can be seen as "defects", are known to control both static and dynamic properties of these one-dimensional systems, their study and understanding are necessary first steps before a deeper discussion of the SCM properties at finite temperature. The starting point of the paper is the simple regular ferromagnetic chain for which the characteristics of the domain walls are well known. Then two cases will be discussed (i) the "mixed chains" in which isotropic and anisotropic classical spins alternate, and (ii) the so-called "canted chains" where two different easy axis directions are present. In particular, we show that "strictly narrow" domain walls no longer exist in these more complex cases, while a cascade of phase transitions is found for canted chains as the canting angle approaches 45∘. The consequence for thermodynamic properties is briefly discussed in the last part of the paper.

  16. Dependence of optical phase modulation on anchoring strength of dielectric shield wall surfaces in small liquid crystal pixels

    Science.gov (United States)

    Isomae, Yoshitomo; Shibata, Yosei; Ishinabe, Takahiro; Fujikake, Hideo

    2018-03-01

    We demonstrated that the uniform phase modulation in a pixel can be realized by optimizing the anchoring strength on the walls and the wall width in the dielectric shield wall structure, which is the needed pixel structure for realizing a 1-µm-pitch optical phase modulator. The anchoring force degrades the uniformity of the phase modulation in ON-state pixels, but it also keeps liquid crystals from rotating against the leakage of an electric field. We clarified that the optimal wall width and anchoring strength are 250 nm and less than 10-4 J/m2, respectively.

  17. Numerical investigation of the onset of centrifugal buoyancy in a rotating cavity

    Science.gov (United States)

    Pitz, Diogo B.; Marxen, Olaf; Chew, John

    2016-11-01

    Buoyancy-induced flows in a differentially heated rotating annulus present a multitude of dynamics when control parameters such as rotation rate, temperature difference and Prandtl number are varied. Whilst most of the work in this area has been motivated by applications involving geophysics, the problem of buoyancy-induced convection in rotating systems is also relevant in industrial applications such as the flow between rotating disks of turbomachinery internal air systems, in which buoyancy plays a major role and poses a challenge to accurately predict temperature distributions and heat transfer rates. In such applications the rotational speeds involved are very large, so that the centrifugal accelerations induced are much higher than gravity. In this work we perform direct numerical simulations and linear stability analysis of flow induced by centrifugal buoyancy in a sealed rotating annulus of finite gap with flat end-walls, using a canonical setup representative of an internal air system rotating cavity. The analysis focuses on the behaviour of small-amplitude disturbances added to the base flow, and how those affect the onset of Rossby waves and, ultimately, the transition to a fully turbulent state where convection columns no longer have a well-defined structure. Diogo B. Pitz acknowledges the financial support from the Capes foundation through the Science without Borders program.

  18. Lattice Boltzmann simulation of viscoelastic flow past a confined free rotating cylinder

    Science.gov (United States)

    Xia, Yi; Zhang, Peijie; Lin, Jianzhong; Ku, Xiaoke; Nie, Deming

    2018-05-01

    To study the dynamics of rigid body immersed in viscoelastic fluid, an Oldroyd-B fluid flow past an eccentrically situated, free rotating cylinder in a two-dimensional (2D) channel is simulated by a novel lattice Boltzmann method. Two distribution functions are employed, one of which is aimed to solve Navier-Stokes equation and the other to the constitutive equation, respectively. The unified interpolation bounce-back scheme is adopted to treat the moving curved boundary of cylinder, and the novel Galilean invariant momentum exchange method is utilized to obtain the hydrodynamic force and torque exerted on the cylinder. Results show that the center-fixed cylinder rotates inversely in the direction where a cylinder immersed in Newtonian fluid do, which generates a centerline-oriented lift force according to Magnus effect. The cylinder’s eccentricity, flow inertia, fluid elasticity and viscosity would affect the rotation of cylinder in different ways. The cylinder rotates more rapidly when located farther away from the centerline, and slows down when it is too close to the wall. The rotation frequency decreases with increasing Reynolds number, and larger rotation frequency responds to larger Weissenberg number and smaller viscosity ratio, indicating that the fluid elasticity and low solvent viscosity accelerates the flow-induced rotation of cylinder.

  19. Implementation of a two-qubit controlled-rotation gate based on unconventional geometric phase with a constant gating time

    International Nuclear Information System (INIS)

    Yabu-uti, B.F.C.; Roversi, J.A.

    2011-01-01

    We propose an alternative scheme to implement a two-qubit controlled-R (rotation) gate in the hybrid atom-CCA (coupled cavities array) system. Our scheme results in a constant gating time and, with an adjustable qubit-bus coupling (atom-resonator), one can specify a particular rotation R on the target qubit. We believe that this proposal may open promising perspectives for networking quantum information processors and implementing distributed and scalable quantum computation. -- Highlights: → We propose an alternative two-qubit controlled-rotation gate implementation. → Our gate is realized in a constant gating time for any rotation. → A particular rotation on the target qubit can be specified by an adjustable qubit-bus coupling. → Our proposal may open promising perspectives for implementing distributed and scalable quantum computation.

  20. Rotating permanent magnet excitation for blood flow measurement.

    Science.gov (United States)

    Nair, Sarath S; Vinodkumar, V; Sreedevi, V; Nagesh, D S

    2015-11-01

    A compact, portable and improved blood flow measurement system for an extracorporeal circuit having a rotating permanent magnetic excitation scheme is described in this paper. The system consists of a set of permanent magnets rotating near blood or any conductive fluid to create high-intensity alternating magnetic field in it and inducing a sinusoidal varying voltage across the column of fluid. The induced voltage signal is acquired, conditioned and processed to determine its flow rate. Performance analysis shows that a sensitivity of more than 250 mV/lpm can be obtained, which is more than five times higher than conventional flow measurement systems. Choice of rotating permanent magnet instead of an electromagnetic core generates alternate magnetic field of smooth sinusoidal nature which in turn reduces switching and interference noises. These results in reduction in complex electronic circuitry required for processing the signal to a great extent and enable the flow measuring device to be much less costlier, portable and light weight. The signal remains steady even with changes in environmental conditions and has an accuracy of greater than 95%. This paper also describes the construction details of the prototype, the factors affecting sensitivity and detailed performance analysis at various operating conditions.

  1. Weak rotating flow disturbances in a centrifugal compressor with a vaneless diffuser

    Science.gov (United States)

    Moore, F. K.

    1988-01-01

    A theory is presented to predict the occurrence of weak rotating waves in a centrifugal compression system with a vaneless diffuser. As in a previous study of axial systems, an undisturbed performance characteristic is assumed known. Following an inviscid analysis of the diffuser flow, conditions for a neutral rotating disturbance are found. The solution is shown to have two branches; one with fast rotation, the other with very slow rotation. The slow branch includes a dense set of resonant solutions. The resonance is a feature of the diffuser flow, and therefore such disturbances must be expected at the various resonant flow coefficients regardless of the compressor characteristic. Slow solutions seem limited to flow coefficients less than about 0.3, where third and fourth harmonics appear. Fast waves seem limited to a first harmonic. These fast and slow waves are described, and effects of diffuser-wall convergence, backward blade angles, and partial recovery of exit velocity head are assessed.

  2. On the inverse Magnus effect for flow past a rotating cylinder

    Science.gov (United States)

    John, Benzi; Gu, Xiao-Jun; Barber, Robert W.; Emerson, David R.

    2016-11-01

    Flow past a rotating cylinder has been investigated using the direct simulation Monte Carlo method. The study focuses on the occurrence of the inverse Magnus effect under subsonic flow conditions. In particular, the variations in the coefficients of lift and drag have been investigated as a function of the Knudsen and Reynolds numbers. Additionally, a temperature sensitivity study has been carried out to assess the influence of the wall temperature on the computed aerodynamic coefficients. It has been found that both the Reynolds number and the cylinder wall temperature significantly affect the drag as well as the onset of lift inversion in the transition flow regime.

  3. \\mathscr{H}_2 optimal control techniques for resistive wall mode feedback in tokamaks

    Science.gov (United States)

    Clement, Mitchell; Hanson, Jeremy; Bialek, Jim; Navratil, Gerald

    2018-04-01

    DIII-D experiments show that a new, advanced algorithm enables resistive wall mode (RWM) stability control in high performance discharges using external coils. DIII-D can excite strong, locked or nearly locked external kink modes whose rotation frequencies and growth rates are on the order of the magnetic flux diffusion time of the vacuum vessel wall. Experiments have shown that modern control techniques like linear quadratic Gaussian (LQG) control require less current than the proportional controller in use at DIII-D when using control coils external to DIII-D’s vacuum vessel. Experiments were conducted to develop control of a rotating n  =  1 perturbation using an LQG controller derived from VALEN and external coils. Feedback using this LQG algorithm outperformed a proportional gain only controller in these perturbation experiments over a range of frequencies. Results from high βN experiments also show that advanced feedback techniques using external control coils may be as effective as internal control coil feedback using classical control techniques.

  4. Advances in Molecular Rotational Spectroscopy for Applied Science

    Science.gov (United States)

    Harris, Brent; Fields, Shelby S.; Pulliam, Robin; Muckle, Matt; Neill, Justin L.

    2017-06-01

    Advances in chemical sensitivity and robust, solid-state designs for microwave/millimeter-wave instrumentation compel the expansion of molecular rotational spectroscopy as research tool into applied science. It is familiar to consider molecular rotational spectroscopy for air analysis. Those techniques for molecular rotational spectroscopy are included in our presentation of a more broad application space for materials analysis using Fourier Transform Molecular Rotational Resonance (FT-MRR) spectrometers. There are potentially transformative advantages for direct gas analysis of complex mixtures, determination of unknown evolved gases with parts per trillion detection limits in solid materials, and unambiguous chiral determination. The introduction of FT-MRR as an alternative detection principle for analytical chemistry has created a ripe research space for the development of new analytical methods and sampling equipment to fully enable FT-MRR. We present the current state of purpose-built FT-MRR instrumentation and the latest application measurements that make use of new sampling methods.

  5. Development and preliminary assessment of the wall condensation heat transfer models for the SPACE code

    International Nuclear Information System (INIS)

    Park, Hyun Sik; Choi, Ki Yong; Moon, Sang Ki; Kim, Jung Woo; Kim, Kyung Doo

    2009-01-01

    The wall condensation heat transfer models are developed for the SPACE code and are assessed for various condensation conditions. Both default and alternative models were selected through an extensive literature survey. For a pure steam condensation, a maximum value among the Nusselt, Chato, and Shah's correlations is used in order to consider the geometric and turbulent effects. In the presence of non-condensable gases, the Colburn-Hougen's diffusion model was used as a default model and a non-iterative condensation model proposed by No and Park was selected as an alternative model. The wall condensation heat transfer models were assessed preliminarily by using arbitrary test conditions. Both wall condensation models could simulate the heat transfer coefficients and heat fluxes in the vertical, horizontal and turbulent conditions quite reasonably for a pure steam condensation. Both the default and alternative wall condensation models were also verified for the condensation heat transfer coefficient and heat flux in the presence of noncondensable gas. However, some improvements and further detailed verification are necessary for the condensation phenomena in the presence of noncondensable gas

  6. Impact of viscosity variation and micro rotation on oblique transport of Cu-water fluid.

    Science.gov (United States)

    Tabassum, Rabil; Mehmood, R; Nadeem, S

    2017-09-01

    This study inspects the influence of temperature dependent viscosity on Oblique flow of micropolar nanofluid. Fluid viscosity is considered as an exponential function of temperature. Governing equations are converted into dimensionless forms with aid of suitable transformations. Outcomes of the study are shown in graphical form and discussed in detail. Results revealed that viscosity parameter has pronounced effects on velocity profiles, temperature distribution, micro-rotation, streamlines, shear stress and heat flux. It is found that viscosity parameter enhances the temperature distribution, tangential velocity profile, normal component of micro-rotation and shear stress at the wall while it has decreasing effect on tangential component of micro-rotation and local heat flux. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Effectiveness of shock wave therapy as an alternative to the rotator cuff injury treatment

    Directory of Open Access Journals (Sweden)

    Roberto Joaquín Del Gordo-D´Amato

    2016-02-01

    Full Text Available Rotator cuff injuries are reason for consultation frequent in elderly patients. Most of the time there are no background traumatic acute generating progressive limitations in activities of daily living (ADLS. The objective of this study is to show results in tendonitis of the rotator cuff, in patients treated with extracorporeal shock wave therapy (ESWT. It is a prospective descriptive observational study which presents clinical and functional outcomes in patients with described lesion, treated with ESWT with poor response to conventional treatments and clinical pictures of longstanding through implementing visual analog scale (VAS of pain and evaluation of range of motion. The greater presence of lesion is present in women 63.6%. Mostly affected shoulder was right in a 63.6%. Found significant changes in VAS pre and post treatment with averages of 7.9 and 0.5 respectively and different statistical p < 0.001. We were conclude that the ESWT is an effective method in the treatment of the tendonitis of the rotator cuff with relief from pain and return to functional levels.

  8. Magneto-Rayleigh-Taylor instability driven by a rotating magnetic field

    Science.gov (United States)

    Duan, Shuchao; Xie, Weiping; Cao, Jintao; Li, Ding

    2018-04-01

    In this paper, we analyze theoretically the magneto-Rayleigh-Taylor instability driven by a rotating magnetic field. Slab configurations of finite thickness are treated both with and without using the Wenzel-Kramers-Brillouin approximation. Regardless of the slab thickness, the directional rotation of the driving magnetic field contributes to suppressing these instabilities. The two factors of the finite thickness and directional rotation of the magnetic field cooperate to enhance suppression, with the finite thickness playing a role only when the orientation of the magnetic field is time varying. The suppression becomes stronger as the driving magnetic field rotates faster, and all modes are suppressed, in contrast to the case of a non-rotating magnetic field, for which the vertical mode cannot be suppressed. This implies that the dynamically alternate configuration of a Theta-pinch and a Z-pinch may be applicable to the concept of Theta-Z liner inertial fusion.

  9. Activity and stability studies of platinized multi-walled carbon nanotubes as fuel cell electrocatalysts

    DEFF Research Database (Denmark)

    Stamatin, Serban Nicolae; Borghei, Maryam; Dhiman, Rajnish

    2015-01-01

    A non-covalent functionalization for multi-walled carbon nanotubes has been used as an alternative to the damaging acid treatment. Platinum nanoparticles with similar particle size distribution have been deposited on the surface modified multi-walled carbon nanotubes. The interaction between...

  10. Analysis, design, and constrution of a sacrificial shield wall

    International Nuclear Information System (INIS)

    Fialkow; Shah, S.B.

    1978-01-01

    The sacrificial shield wall, a cylindrical enclosure around the reactor pressure vessel (RPV), is a major component of nuclear power plants of the Boiling Water Reactor (BWR) type. A method developed for the analysis and design of such walls is described which eliminates shortcomings in methods used in current practice. The method treats the wall as a space frame of ring beams and columns and includes the skin plates as finite elements. Design loadings, load combinations, and acceptance criteria are presented. Results by this method are furnished and compared with results by an alternate method. Significant design features are described and a narrative of construction procedures is included. (Author)

  11. Unsteady flow over a decelerating rotating sphere

    Science.gov (United States)

    Turkyilmazoglu, M.

    2018-03-01

    Unsteady flow analysis induced by a decelerating rotating sphere is the main concern of this paper. A revolving sphere in a still fluid is supposed to slow down at an angular velocity rate that is inversely proportional to time. The governing partial differential equations of motion are scaled in accordance with the literature, reducing to the well-documented von Kármán equations in the special circumstance near the pole. Both numerical and perturbation approaches are pursued to identify the velocity fields, shear stresses, and suction velocity far above the sphere. It is detected that an induced flow surrounding the sphere acts accordingly to adapt to the motion of the sphere up to some critical unsteadiness parameters at certain latitudes. Afterward, the decay rate of rotation ceases such that the flow at the remaining azimuths starts revolving freely. At a critical unsteadiness parameter corresponding to s = -0.681, the decelerating sphere rotates freely and requires no more torque. At a value of s exactly matching the rotating disk flow at the pole identified in the literature, the entire flow field around the sphere starts revolving faster than the disk itself. Increasing values of -s almost diminish the radial outflow. This results in jet flows in both the latitudinal and meridional directions, concentrated near the wall region. The presented mean flow results will be useful for analyzing the instability features of the flow, whether of a convective or absolute nature.

  12. Successful Expansion of an Underexpanded Stent by Rotational Atherectomy

    Science.gov (United States)

    Vales, Lori; Coppola, John; Kwan, Tak

    2013-01-01

    The current routine use of intracoronary stents in percutaneous coronary intervention (PCI) has significantly reduced rates of restenosis, compared with balloon angioplasty alone. On the contrary, small post-stenting luminal dimensions due to undilatable, heavily calcified plaques have repeatedly been shown to significantly increase the rates of in-stent restenosis. Rotational atherectomy of lesions is an alternative method to facilitate PCI and prevent underexpansion of stents, when balloon angioplasty fails to successfully dilate a lesion. Stentablation, using rotational atherectomy to expand underexpanded stents deployed in heavily calcified plaques, has also been reported. We report a case via the transradial approach of rotational-atherectomy–facilitated PCI of in-stent restenosis of a severely underexpanded stent due to a heavily calcified plaque. We review the literature and suggest rotational atherectomy may have a role in treating a refractory, severely underexpanded stent caused by a heavily calcified plaque through various proposed mechanisms. PMID:24436587

  13. Polar octahedral rotations: A path to new multifunctional materials

    International Nuclear Information System (INIS)

    Benedek, Nicole A.; Mulder, Andrew T.; Fennie, Craig J.

    2012-01-01

    Perovskite ABO 3 oxides display an amazing variety of phenomena that can be altered by subtle changes in the chemistry and internal structure, making them a favorite class of materials to explore the rational design of novel properties. Here we highlight a recent advance in which rotations of the BO 6 octahedra give rise to a novel form of ferroelectricity – hybrid improper ferroelectricity. Octahedral rotations also strongly influence other structural, magnetic, orbital, and electronic degrees of freedom in perovskites and related materials. Octahedral rotation-driven ferroelectricity consequently has the potential to robustly control emergent phenomena with an applied electric field. The concept of ‘functional’ octahedral rotations is introduced and the challenges for materials chemistry and the possibilities for new rotation-driven phenomena in multifunctional materials are explored. - Graphical abstract: A 3 B 2 O 7 and (A/A′)B 2 O 6 are two types of layered perovskites in which octahedral rotations induce ferroelectricity. Highlights: ► Recent progress on achieving ferroelectricity from rotations of the BO 6 octahedra in ABO 3 perovskite oxides is reviewed. ► The atomic scale layering of Pnma perovskites in two different ways leads to alternative structure realizations. ► The concept of ‘functional’ octahedral rotations is introduced as a path to electric-field control of emergent phenomena.

  14. Prevalence and histopathological finding of thin-walled and thick-walled Sarcocysts in slaughtered cattle of Karaj abattoir, Iran.

    Science.gov (United States)

    Nourollahi-Fard, Saeid R; Kheirandish, Reza; Sattari, Saeid

    2015-06-01

    Sarcocystosis is a zoonotic disease caused by Sarcocystis spp. with obligatory two host life cycle generally alternating between an herbivorous intermediate host and a carnivorous definitive host. Some species of this coccidian parasite can cause considerable morbidity and mortality in cattle. The present study was set to investigate the prevalence of Sarcocystis spp. and type of cyst wall in slaughtered cattle of Karaj abattoir, Iran. For this purpose 125 cattle (88 males and 37 females) were investigated for the presence of macroscopic and microscopic Sarcocystis cysts in muscular tissues. No macroscopic Sarcocystis cysts were found in any of the samples. In light microscopy, 121 out of 125 cattle (96.8 %) had thin-walled cysts of Sarcocystis cruzi, while 43 out of them (34.4 %) had thick-walled Sarcocystis cyst. In this survey, the most infected tissue was esophagus and heart and the less was diaphragm. Thin-walled cysts (S. cruzi) mostly found in heart and skeletal muscle showed the less. However, thick-walled cyst (S. hominis or S. hirsuta) mostly were detected in diaphragm, heart muscle showed no thick-walled cyst. No significant relation was observed between age and sex and the rate of infection. The results showed that Sarcocystis cyst is prevalent in cattle in the North part of Iran and the evaluation of infection potential can be useful when considering control programs.

  15. Prototype gauge for measuring contour and wall thicknesses of hemispherical parts

    International Nuclear Information System (INIS)

    Aarts, H.J.; Robertson, J.H.

    1976-01-01

    A prototype gauge (gage) was designed and fabricated using air bearings in a new configuration to provide less error and distortion during inspection of hemispherical parts. No wear occurs on the moving parts during operations and accuracy of alignment is maintained. The gauge will check outside radial distance, inside radial, and outside radial and wall, and inner radial and wall thicknesses of parts. The gauge contains only four moving parts, which increases the measuring accuracy. A horizontal table rotates. A table mounted on the horizontal table at 45 0 rotates through two transducers. All moving parts are mounted on hydrostatic gas bearings. Laser interferometric, air-bearing gauge heads are used to obtain the required data. Investigation of a hemispherical part is in any desired spiral path from equator to pole. Measurement information is obtained from two laser interferometric transducers using linear air bearings. The transducers use a Spectra Physics Model-120 helium and neon laser. Working range of each transducer is 1.5 inches. The fringe voltage signals are amplified and converted to inches to be displayed on a digital readout. A punched paper tape contains the nominal inside diameter (ID) and outside diameter (OD) information in Binary Coded Decimal form. The tape is fed into a digital computer which calculates error information on ID, OD, and wall thickness. This information is converted to analog form and displayed simultaneously on a strip-chart recorder

  16. Topographic instability of flow in a rotating fluid

    Directory of Open Access Journals (Sweden)

    K. I. Patarashvili

    2006-01-01

    Full Text Available Here are presented the results of experimental and theoretical studies on a stability of zonal geostrophic flows in the rotating layer of the shallow water. In the experiments, a special apparatus by Abastumani Astrophysical Observatory Georgian Academy of Science was used. This apparatus represents a paraboloid of rotation, which can be set in a regulable rotation around the vertical axis. Maximal diameter of the paraboloid is 1.2 m, radius of curvature in the pole is 0.698 m. In the paraboloid, water spreads on walls as a layer uniform on height under the period of rotation 1.677 s. Against a background of the rotating fluid, the zonal flows are formed by the source-sink system. It consists of two concentric circular perforations on the paraboloid bottom (width is 0.3 cm, radiuses are 8.4 and 57.3 cm, respectively; water can be pumped through them with various velocities and in all directions. It has been established that under constant vertical depth of the rotating fluid the zonal flows are stable. There are given the measurements of the radial profiles for the water level and velocity in the stationary regime. It has been found that zonal flows may lose stability under the presence of the radial gradient of full depth formed by a change of angular velocity of paraboloid rotation. An instability origin results in the loss of flow axial symmetry and in the appearance of self-excited oscillations in the zonal flow. At the given angular velocity of rotation, instability is observed only in the definite range of intensities of the source-sink system. The theoretical estimations are performed in the framework of the equations of the shallow water theory, including the terms describing the bottom friction. It has been shown that the instability of zonal flows found experimentally has a topographical nature and is related with non-monotone dependence of the potential vorticity on radius.

  17. Experimental study of a particle velocity immersed in a fluid in rotation

    International Nuclear Information System (INIS)

    Cesar, S.B.G.

    1981-12-01

    An incompressible viscous fluid is confined within a circular cylinder whose wall and top are fixed while the botton rotates with constant angular speed. The velocity components of a particule immersed in the fluid above, was determined. The method utilized employs filming the particle during its motion. Experimental measurements were made at rotational speeds between 50 and 190 rps, at inter-disc spacing between 10 and 40 cm, and the particle is let loose at distances between static disc and 5 cm above the inferior disc. The results show that the method utilized is valid in a radial region within the cylinder between 1.0 [pt

  18. Measurement of guided light-mode intensity: An alternative waveguide sensing principle

    DEFF Research Database (Denmark)

    Horvath, R.; Skivesen, N.; Pedersen, H.C.

    2004-01-01

    An alternative transduction mechanism for planar optical waveguide sensors is reported. Based on a simple measurement of the mode intensity, the presented transduction is an interesting alternative to the conventional mode-angle transduction, because the expensive, high-precision angular rotation...

  19. Seismic behavior and design of wall-EDD-frame systems

    Directory of Open Access Journals (Sweden)

    Oren eLavan

    2015-06-01

    Full Text Available Walls and frames have different deflection lines and, depending on the seismic mass they support, may often poses different natural periods. In many cases, wall-frame structures present an advantageous behavior. In these structures the walls and the frames are rigidly connected. Nevertheless, if the walls and the frames were not rigidly connected, an opportunity for an efficient passive control strategy would arise: Connecting the two systems by energy dissipation devices (EDDs to result in wall-EDD-frame systems. This, depending on the parameters of the system, is expected to lead to an efficient energy dissipation mechanism.This paper studies the seismic behavior of wall-EDD-frame systems in the context of retrofitting existing frame structures. The controlling non-dimensional parameters of such systems are first identified. This is followed by a rigorous and extensive parametric study that reveals the pros and cons of the new system versus wall-frame systems. The effect of the controlling parameters on the behavior of the new system are analyzed and discussed. Finally, tools are given for initial design of such retrofitting schemes. These enable both choosing the most appropriate retrofitting alternative and selecting initial values for its parameters.

  20. Deflection Prediction of No-Fines Lightweight Concrete Wall Using Neural Network Caused Dynamic Loads

    Directory of Open Access Journals (Sweden)

    Ridho Bayuaji

    2018-04-01

    Full Text Available No-fines lightweight concrete wall with horizontal reinforcement refers to an alternative material for wall construction with an aim of improving the wall quality towards horizontal loads. This study is focused on artificial neural network (ANN application to predicting the deflection deformation caused by dynamic loads. The ANN method is able to capture the complex interactions among input/output variables in a system without any knowledge of interaction nature and without any explicit assumption to model form. This paper explains the existing data research, data selection and process of ANN modelling training process and validation. The results of this research show that the deformation can be predicted more accurately, simply and quickly due to the alternating horizontal loads.

  1. Steady supersonic rotation in the Maryland Centrifugal Experiment

    International Nuclear Information System (INIS)

    Ellis, R.F.; Messer, S.; Case, A.; DeSilva, A.; Elton, R.; Ghosh, J.; Griem, H.; Gupta, D.; Hassam, A.; Lunsford, R.; McLaren, R.; Rodgers, J.; Teodorescu, C.

    2005-01-01

    The Maryland Centrifugal Experiment (MCX) studies enhanced confinement and stability produced by sheared supersonic rotation about a linear confining magnetic field. MCX has a mirror geometry of 2.5 m length, mirror ratio 2-20, maximum mirror field 1.9T, maximum midplane field 0.33T. Biasing of an inner electrode relative to the outer wall produces a radial electric field which drives azimuthal rotation. MCX has achieved high density (n>10 20 m -3 ) fully ionized plasmas rotating supersonically with velocities of ∼100 km/sec for times exceeding 8 ms under a wide range of conditions. Ion temperatures are 30 eV and confinement times ∼100 microseconds. Sonic Mach numbers are 1-2 and Alfven Mach numbers somewhat less than 0.5 for standard discharges. Plasmas remain grossly stable, or steady, for many milliseconds, much longer than MHD instability timescales for MCX, though significant magnetic fluctuations are clearly seen on magnetic probes. Recently MCX has demonstrated an enhanced mode of operation with sonic Mach numbers greater than 3, confinement times of several hundred microseconds and Alfven Mach numbers near one. (author)

  2. Arc dynamics of a pulsed DC nitrogen rotating gliding arc discharge

    Science.gov (United States)

    Zhu, Fengsen; Zhang, Hao; Li, Xiaodong; Wu, Angjian; Yan, Jianhua; Ni, Mingjiang; Tu, Xin

    2018-03-01

    In this study, a novel pulsed direct current (DC) rotating gliding arc (RGA) plasma reactor co-driven by an external magnetic field and a tangential gas flow has been developed. The dynamic characteristics of the rotating gliding arc have been investigated by means of numerical simulation and experiment. The simulation results show that a highly turbulent vortex flow can be generated at the bottom of the RGA reactor to accelerate the arc rotation after arc ignition, whereas the magnitude of gas velocity declined significantly along the axial direction of the RGA reactor. The calculated arc rotation frequency (14.4 Hz) is reasonably close to the experimental result (18.5 Hz) at a gas flow rate of 10 l min-1. In the presence of an external magnet, the arc rotation frequency is around five times higher than that of the RGA reactor without using a magnet, which suggests that the external magnetic field plays a dominant role in the maintenance of the arc rotation in the upper zone of the RGA reactor. In addition, when the magnet is placed outside the reactor reversely to form a reverse external magnetic field, the arc can be stabilized at a fixed position in the inner wall of the outer electrode at a critical gas flow rate of 16 l min-1.

  3. Direct numerical simulation of turbulent channel flow with spanwise alternatively distributed strips control

    Science.gov (United States)

    Ni, Weidan; Lu, Lipeng; Fang, Jian; Moulinec, Charles; Yao, Yufeng

    2018-05-01

    The effect of spanwise alternatively distributed strips (SADS) control on turbulent flow in a plane channel has been studied by direct numerical simulations to investigate the characteristics of large-scale streamwise vortices (LSSVs) induced by small-scale active wall actuation, and their potential in suppressing flow separation. SADS control is realized by alternatively arranging out-of-phase control (OPC) and in-phase control (IPC) wall actuations on the lower channel wall surface, in the spanwise direction. It is found that the coherent structures are suppressed or enhanced alternatively by OPC or IPC, respectively, leading to the formation of a vertical shear layer, which is responsible for the LSSVs’ presence. Large-scale low-speed region can also be observed above the OPC strips, which resemble large-scale low-speed streaks. LSSVs are found to be in a statistically-converged steady state and their cores are located between two neighboring OPC and IPC strips. Their motions contribute significantly to the momentum transport in the wall-normal and spanwise directions, demonstrating their potential ability to suppress flow separation.

  4. Tissue-engineering with muscle fiber fragments improves the strength of a weak abdominal wall in rats

    DEFF Research Database (Denmark)

    Jangö, Hanna; Gräs, Søren; Christensen, Lise

    2017-01-01

    INTRODUCTION AND HYPOTHESIS: Alternative approaches to reinforce the native tissue in patients with pelvic organ prolapse (POP) are needed to improve surgical outcome. Our aims were to develop a weakened abdominal wall in a rat model to mimic the weakened vaginal wall in women with POP and then e...... showed a significantly higher strength than the group with MPEG-PLGA alone (p = 0.034). CONCLUSION: Tissue-engineering with MFFs seeded on a scaffold of biodegradable MPEG-PLGA might be an interesting adjunct to future POP repair.......INTRODUCTION AND HYPOTHESIS: Alternative approaches to reinforce the native tissue in patients with pelvic organ prolapse (POP) are needed to improve surgical outcome. Our aims were to develop a weakened abdominal wall in a rat model to mimic the weakened vaginal wall in women with POP...

  5. Laminar boundary layer response to rotation of a finite diameter surface patch

    International Nuclear Information System (INIS)

    Klewicki, J.C.; Hill, R.B.

    2003-01-01

    The responses of the flat plate laminar boundary layer to perturbations generated by rotating a finite patch of the bounding surface are explored experimentally. The size of the surface patch was of the same order as the boundary layer thickness. The displacement thickness Reynolds number range of the boundary layers explored was 72-527. The rotation rates of the surface patch ranged from 2.14 to 62.8 s-1. Qualitative flow visualizations and quantitative molecular tagging velocimetry measurements revealed that rotation of a finite surface patch generates an asymmetric loop-like vortex. Significant features of this vortex include that, (i) the sign of the vorticity in the vortex head is opposite that of the boundary layer vorticity regardless of the sign of the input rotation, (ii) one leg of the vortex exhibits motion akin to solid body rotation while the other leg is best characterized as a spanwise shear layer, (iii) the vortex leg exhibiting near solid body rotation lifts more rapidly from the surface than the leg more like a shear layer, and (iv) the vortex leg exhibiting near solid body rotation always occurs on the side of the surface patch experiencing downstream motion. These asymmetries switch sides depending on the sign of the input rotation. The present results are interpreted and discussed relative to analytical solutions for infinite geometries. By way of analogy, plausible connections are drawn between the present results and the influences of wall normal vortices in turbulent boundary layer flows

  6. Steady-state temperature distribution within a Brayton rotating unit operating in a power conversion system using helium-xenon gas

    Science.gov (United States)

    Johnsen, R. L.; Namkoong, D.; Edkin, R. A.

    1971-01-01

    The Brayton rotating unit (BRU), consisting of a turbine, an alternator, and a compressor, was tested as part of a Brayton cycle power conversion system over a side range of steady state operating conditions. The working fluid in the system was a mixture of helium-xenon gases. Turbine inlet temperature was varied from 1200 to 1600 F, compressor inlet temperature from 60 to 120 F, compressor discharge pressure from 20 to 45 psia, rotative speed from 32 400 to 39 600 rpm, and alternator liquid-coolant flow rate from 0.01 to 0.27 pound per second. Test results indicated that the BRU internal temperatures were highly sensitive to alternator coolant flow below the design value of 0.12 pound per second but much less so at higher values. The armature winding temperature was not influenced significantly by turbine inlet temperature, but was sensitive, up to 20 F per kVA alternator output, to varying alternator output. When only the rotational speed was changed (+ or - 10% of rated value), the BRU internal temperatures varied directly with the speed.

  7. Low-Cost Alternative External Rotation Shoulder Brace and Review of Treatment in Acute Shoulder Dislocations

    Directory of Open Access Journals (Sweden)

    Lacy, Kyle

    2015-01-01

    Full Text Available Traumatic dislocations of the shoulder commonly present to emergency departments (EDs. Immediate closed reduction of both anterior and posterior glenohumeral dislocations is recommended and is frequently performed in the ED. Recurrence of dislocation is common, as anteroinferior labral tears (Bankart lesions are present in many anterior shoulder dislocations.14,15,18,23 Immobilization of the shoulder following closed reduction is therefore recommended; previous studies support the use of immobilization with the shoulder in a position of external rotation, for both anterior and posterior shoulder dislocations.7-11,19 In this study, we present a technique for assembling a low-cost external rotation shoulder brace using materials found in most hospitals: cotton roll, stockinette, and shoulder immobilizers. This brace is particularly suited for the uninsured patient, who lacks the financial resources to pay for a pre-fabricated brace out of pocket. We also performed a cost analysis for our low-cost external rotation shoulder brace, and a cost comparison with pre-fabricated brand name braces. At our institution, the total materials cost for our brace was $19.15. The cost of a pre-fabricated shoulder brace at our institution is $150 with markup, which is reimbursed on average at $50.40 according to our hospital billing data. The low-cost external rotation shoulder brace is therefore a more affordable option for the uninsured patient presenting with acute shoulder dislocation. [West J Emerg Med. 2015;16(1:114–120.

  8. Feedback control of resistive wall modes in toroidal devices

    International Nuclear Information System (INIS)

    Liu, Y.Q.

    2002-01-01

    Active feedback of resistive wall modes is investigated using cylindrical theory and toroidal calculations. For tokamaks, good performance is obtained by using active coils with one set of coils in the poloidal direction and sensors detecting the poloidal field inside the first wall, located at the outboard mid-plane. With suitable width of the feedback coil such a system can give robust control with respect to variations in plasma current, pressure and rotation. Calculations are shown for ITER-like geometry with a double wall. The voltages and currents in the active coils are well within the design limits for ITER. Calculations for RFP's are presented for a finite number of coils both in the poloidal and toroidal directions. With 4 coils in the poloidal and 24 coils in the toroidal direction, all non-resonant modes can be stabilized both at high and low theta. Several types of sensors, including radial and internal poloidal or toroidal sensors, can stabilize the RWM, but poloidal sensors give the most robust performance. (author)

  9. Multihelix rotating shield brachytherapy for cervical cancer

    Energy Technology Data Exchange (ETDEWEB)

    Dadkhah, Hossein [Department of Biomedical Engineering, University of Iowa, 1402 Seamans Center for the Engineering Arts and Sciences, Iowa City, Iowa 52242 (United States); Kim, Yusung; Flynn, Ryan T., E-mail: ryan-flynn@uiowa.edu [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Wu, Xiaodong [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 and Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center for the Engineering Arts and Sciences, Iowa City, Iowa 52242 (United States)

    2015-11-15

    Purpose: To present a novel brachytherapy technique, called multihelix rotating shield brachytherapy (H-RSBT), for the precise angular and linear positioning of a partial shield in a curved applicator. H-RSBT mechanically enables the dose delivery using only linear translational motion of the radiation source/shield combination. The previously proposed approach of serial rotating shield brachytherapy (S-RSBT), in which the partial shield is rotated to several angular positions at each source dwell position [W. Yang et al., “Rotating-shield brachytherapy for cervical cancer,” Phys. Med. Biol. 58, 3931–3941 (2013)], is mechanically challenging to implement in a curved applicator, and H-RSBT is proposed as a feasible solution. Methods: A Henschke-type applicator, designed for an electronic brachytherapy source (Xoft Axxent™) and a 0.5 mm thick tungsten partial shield with 180° or 45° azimuthal emission angles and 116° asymmetric zenith angle, is proposed. The interior wall of the applicator contains six evenly spaced helical keyways that rigidly define the emission direction of the partial radiation shield as a function of depth in the applicator. The shield contains three uniformly distributed protruding keys on its exterior wall and is attached to the source such that it rotates freely, thus longitudinal translational motion of the source is transferred to rotational motion of the shield. S-RSBT and H-RSBT treatment plans with 180° and 45° azimuthal emission angles were generated for five cervical cancer patients with a diverse range of high-risk target volume (HR-CTV) shapes and applicator positions. For each patient, the total number of emission angles was held nearly constant for S-RSBT and H-RSBT by using dwell positions separated by 5 and 1.7 mm, respectively, and emission directions separated by 22.5° and 60°, respectively. Treatment delivery time and tumor coverage (D{sub 90} of HR-CTV) were the two metrics used as the basis for evaluation and

  10. An analysis of plasma ion toroidal rotation during large amplitude MHD activity in JET

    International Nuclear Information System (INIS)

    Snipes, J.A.; Esch, H.P.L. de; Lazzaro, E.; Stork, D.; Hellermann, M. von; Galvao, R.; Hender, T.C.; Zasche, D.

    1989-01-01

    A detailed study of plasma ion toroidal rotation in JET during large amplitude MHD activity has revealed a strong viscous force that couples plasma ions to MHD modes. Depending on the MHD modes present, this force can couple across all of the plasma cross section, across only the central region, roughly within the q=1 surface, or across only the outer region outside the q=1.5 surface. The force acts to flatten the ion toroidal rotation frequency profile, measured by the JET active charge exchange spectroscopy diagnostic, across the coupled region of plasma. The frequency of rotation in this region agrees with the MHD oscillation frequency measured by magnetic pick-up coils at the wall. The strength of the force between the ions and modes becomes evident during high power NBI when the mode locks and drags the ion toroidal rotation frequency to zero, within the errors of the measurements. The present theories of plasma rotation either ignore MHD effects entirely, consider only moderate n toroidal field ripple, or low n ripple effects. (author) 7 refs., 3 figs

  11. Lipid-linked cell wall precursors regulate membrane association of bacterial actin MreB.

    Science.gov (United States)

    Schirner, Kathrin; Eun, Ye-Jin; Dion, Mike; Luo, Yun; Helmann, John D; Garner, Ethan C; Walker, Suzanne

    2015-01-01

    The bacterial actin homolog MreB, which is crucial for rod shape determination, forms filaments that rotate around the cell width on the inner surface of the cytoplasmic membrane. What determines filament association with the membranes or with other cell wall elongation proteins is not known. Using specific chemical and genetic perturbations while following MreB filament motion, we find that MreB membrane association is an actively regulated process that depends on the presence of lipid-linked peptidoglycan precursors. When precursors are depleted, MreB filaments disassemble into the cytoplasm, and peptidoglycan synthesis becomes disorganized. In cells that lack wall teichoic acids but continue to make peptidoglycan, dynamic MreB filaments are observed, although their presence is not sufficient to establish a rod shape. We propose that the cell regulates MreB filament association with the membrane, allowing rapid and reversible inactivation of cell wall enzyme complexes in response to the inhibition of cell wall synthesis.

  12. Hall current and Joule heating effects on peristaltic flow of viscous fluid in a rotating channel with convective boundary conditions

    Directory of Open Access Journals (Sweden)

    Tasawar Hayat

    Full Text Available The present article has been arranged to study the Hall current and Joule heating effects on peristaltic flow of viscous fluid in a channel with flexible walls. Both fluid and channel are in a state of solid body rotation. Convective conditions for heat transfer in the formulation are adopted. Viscous dissipation in energy expression is taken into account. Resulting differential systems after invoking small Reynolds number and long wavelength considerations are numerically solved. Runge-Kutta scheme of order four is implemented for the results of axial and secondary velocities, temperature and heat transfer coefficient. Comparison with previous limiting studies is shown. Outcome of new parameters of interest is analyzed. Keywords: Rotating frame, Hall current, Joule heating, Convective conditions, Wall properties

  13. Estimation of the Rotational Terms of the Dynamic Response Matrix

    Directory of Open Access Journals (Sweden)

    D. Montalvão

    2004-01-01

    Full Text Available The dynamic response of a structure can be described by both its translational and rotational receptances. The latter ones are frequently not considered because of the difficulties in applying a pure moment excitation or in measuring rotations. However, in general, this implies a reduction up to 75% of the complete model. On the other hand, if a modification includes a rotational inertia, the rotational receptances of the unmodified system are needed. In one method, more commonly found in the literature, a so called T-block is attached to the structure. Then, a force, applied to an arm of the T-block, generates a moment together with a force at the connection point. The T-block also allows for angular displacement measurements. Nevertheless, the results are often not quite satisfactory. In this work, an alternative method based upon coupling techniques is developed, in which rotational receptances are estimated without the need of applying a moment excitation. This is accomplished by introducing a rotational inertia modification when rotating the T-block. The force is then applied in its centroid. Several numerical and experimental examples are discussed so that the methodology can be clearly described. The advantages and limitations are identified within the practical application of the method.

  14. Report of the IAU Working Group on cartographic coordinates and rotational elements: 2009

    Science.gov (United States)

    Archinal, Brent A.; A’Hearn, Michael F.; Bowell, Edward; Conrad, Al; Consolmagno, Guy J.; Courtin, Regis; Fukushima, Toshio; Hestroffer, Daniel; Hilton, James L.; Krasinsky, Georgij A.; Neumann, Gregory; Oberst, Jurgen; Seidelmann, P. Kenneth; Stooke, Philip; Tholen, David J.; Thomas, Peter C.; Williams, Iwan P.

    2010-01-01

    Every three years the IAU Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report takes into account the IAU Working Group for Planetary System Nomenclature (WGPSN) and the IAU Committee on Small Body Nomenclature (CSBN) definition of dwarf planets, introduces improved values for the pole and rotation rate of Mercury, returns the rotation rate of Jupiter to a previous value, introduces improved values for the rotation of five satellites of Saturn, and adds the equatorial radius of the Sun for comparison. It also adds or updates size and shape information for the Earth, Mars’ satellites Deimos and Phobos, the four Galilean satellites of Jupiter, and 22 satellites of Saturn. Pole, rotation, and size information has been added for the asteroids (21) Lutetia, (511) Davida, and (2867) Šteins. Pole and rotation information has been added for (2) Pallas and (21) Lutetia. Pole and rotation and mean radius information has been added for (1) Ceres. Pole information has been updated for (4) Vesta. The high precision realization for the pole and rotation rate of the Moon is updated. Alternative orientation models for Mars, Jupiter, and Saturn are noted. The Working Group also reaffirms that once an observable feature at a defined longitude is chosen, a longitude definition origin should not change except under unusual circumstances. It is also noted that alternative coordinate systems may exist for various (e.g. dynamical) purposes, but specific cartographic coordinate system information continues to be recommended for each body. The Working Group elaborates on its purpose, and also announces its plans to occasionally provide limited updates to its recommendations via its website, in order to address community needs for some updates more often than every 3 years. Brief recommendations are also made to the

  15. Report of the IAU Working Group on cartographic coordinates and rotational elements: 2009

    Science.gov (United States)

    Archinal, B.A.; A'Hearn, M.F.; Bowell, E.; Conrad, A.; Consolmagno, G.J.; Courtin, R.; Fukushima, T.; Hestroffer, D.; Hilton, J.L.; Krasinsky, G.A.; Neumann, G.; Oberst, J.; Seidelmann, P.K.; Stooke, P.; Tholen, D.J.; Thomas, P.C.; Williams, I.P.

    2010-01-01

    Every three years the IAU Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report takes into account the IAU Working Group for Planetary System Nomenclature (WGPSN) and the IAU Committee on Small Body Nomenclature (CSBN) definition of dwarf planets, introduces improved values for the pole and rotation rate of Mercury, returns the rotation rate of Jupiter to a previous value, introduces improved values for the rotation of five satellites of Saturn, and adds the equatorial radius of the Sun for comparison. It also adds or updates size and shape information for the Earth, Mars’ satellites Deimos and Phobos, the four Galilean satellites of Jupiter, and 22 satellites of Saturn. Pole, rotation, and size information has been added for the asteroids (21) Lutetia, (511) Davida, and (2867) Šteins. Pole and rotation information has been added for (2) Pallas and (21) Lutetia. Pole and rotation and mean radius information has been added for (1) Ceres. Pole information has been updated for (4) Vesta. The high precision realization for the pole and rotation rate of the Moon is updated. Alternative orientation models for Mars, Jupiter, and Saturn are noted. The Working Group also reaffirms that once an observable feature at a defined longitude is chosen, a longitude definition origin should not change except under unusual circumstances. It is also noted that alternative coordinate systems may exist for various (e.g. dynamical) purposes, but specific cartographic coordinate system information continues to be recommended for each body. The Working Group elaborates on its purpose, and also announces its plans to occasionally provide limited updates to its recommendations via its website, in order to address community needs for some updates more often than every 3 years. Brief recommendations are also made to the general

  16. Faraday rotation due to excitation of magnetoplasmons in graphene microribbons.

    Science.gov (United States)

    Tymchenko, Mykhailo; Nikitin, Alexey Yu; Martín-Moreno, Luis

    2013-11-26

    A single graphene sheet, when subjected to a perpendicular static magnetic field, provides a Faraday rotation that, per atomic layer, greatly surpasses that of any other known material. In continuous graphene, Faraday rotation originates from the cyclotron resonance of massless carriers, which allows dynamical tuning through either external electrostatic or magneto-static setting. Furthermore, the rotation direction can be controlled by changing the sign of the carriers in graphene, which can be done by means of an external electric field. However, despite these tuning possibilities, the requirement of large magnetic fields hinders the application of the Faraday effect in real devices, especially for frequencies higher than a few terahertz. In this work we demonstrate that large Faraday rotation can be achieved in arrays of graphene microribbons, through the excitation of the magnetoplasmons of individual ribbons, at larger frequencies than those dictated by the cyclotron resonance. In this way, for a given magnetic field and chemical potential, structuring graphene periodically can produce large Faraday rotation at larger frequencies than what would occur in a continuous graphene sheet. Alternatively, at a given frequency, graphene ribbons produce large Faraday rotation at much smaller magnetic fields than in continuous graphene.

  17. Sidewall containment of liquid metal with horizontal alternating magnetic fields

    Science.gov (United States)

    Pareg, Walter F.

    1990-01-01

    An apparatus for confining molten metal with a horizontal alternating magnetic field. In particular, this invention employs a magnet that can produce a horizontal alternating magnetic field to confine a molten metal at the edges of parallel horizontal rollers as a solid metal sheet is cast by counter-rotation of the rollers.

  18. Statistical orientation fluctuations: constant angular momentum versus constant rotational frequency constraints

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, A L [Tulane Univ., New Orleans, LA (United States)

    1992-08-01

    Statistical orientation fluctuations are calculated with two alternative assumptions: the rotational frequency remains constant as the shape orientation fluctuates; and, the average angular momentum remains constant as the shape orientation fluctuates. (author). 2 refs., 3 figs.

  19. Induced fluid rotation and bistable fluidic turn-down valves (a survey

    Directory of Open Access Journals (Sweden)

    Tesař Václav

    2015-01-01

    Full Text Available Paper surveys engineering applications of an unusual fluidic principle — momentum transfer through a relatively small communicating window into a vortex chamber, where the initially stationary fluid is put into rotation. The transfer is often by shear stress acting in the window plane, but may be enhanced and perhaps even dominated by fluid flow crossing the boundary. The case of zero-time-mean fluid transport through the window has found use in experimental fluid mechanics: non-invasive measurement of wall shear stress on objects by evaluating the induced rotation in the vortex chamber. The case with the non-zero flow through the interface became the starting point in development of fluidic valves combining two otherwise mutually incompatible properties: bistability and flow turning down.

  20. Rapidly rotating single late-type giants: New FK Comae stars?

    Science.gov (United States)

    Fekel, Francis C.

    1986-01-01

    A group of rapidly rotating single late-type giants was found from surveys of chromospherically active stars. These stars have V sin I's ranging from 6 to 46 km/sec, modest ultraviolet emission line fluxes, and strong H alpha absorption lines. Although certainly chromospherically active, their characteristics are much less extreme than those of FK Com and one or two other similar systems. One possible explanation for the newly identified systems is that they have evolved from stars similar to FK Com. The chromospheric activity and rotation of single giant stars like FK Com would be expected to decrease with time as they do in single dwarfs. Alternatively, this newly identified group may have evolved from single rapidly rotating A, or early F stars.

  1. Rotator cuff tendon connections with the rotator cable.

    Science.gov (United States)

    Rahu, Madis; Kolts, Ivo; Põldoja, Elle; Kask, Kristo

    2017-07-01

    The literature currently contains no descriptions of the rotator cuff tendons, which also describes in relation to the presence and characteristics of the rotator cable (anatomically known as the ligamentum semicirculare humeri). The aim of the current study was to elucidate the detailed anatomy of the rotator cuff tendons in association with the rotator cable. Anatomic dissection was performed on 21 fresh-frozen shoulder specimens with an average age of 68 years. The rotator cuff tendons were dissected from each other and from the glenohumeral joint capsule, and the superior glenohumeral, coracohumeral, coracoglenoidal and semicircular (rotator cable) ligaments were dissected. Dissection was performed layer by layer and from the bursal side to the joint. All ligaments and tendons were dissected in fine detail. The rotator cable was found in all specimens. It was tightly connected to the supraspinatus (SSP) tendon, which was partly covered by the infraspinatus (ISP) tendon. The posterior insertion area of the rotator cable was located in the region between the middle and inferior facets of the greater tubercle of the humerus insertion areas for the teres minor (TM), and ISP tendons were also present and fibres from the SSP extended through the rotator cable to those areas. The connection between the rotator cable and rotator cuff tendons is tight and confirms the suspension bridge theory for rotator cuff tears in most areas between the SSP tendons and rotator cable. In its posterior insertion area, the rotator cable is a connecting structure between the TM, ISP and SSP tendons. These findings might explain why some patients with relatively large rotator cuff tears can maintain seamless shoulder function.

  2. Functional residual capacity increase during laparoscopic surgery with abdominal wall lift

    Directory of Open Access Journals (Sweden)

    Hiroshi Ueda

    Full Text Available Abstract Background and objectives: The number of laparoscopic surgeries performed is increasing every year and in most cases the pneumoperitoneum method is used. One alternative is the abdominal wall lifting method and this study was undertaken to evaluate changes of functional residual capacity during the abdominal wall lift procedure. Methods: From January to April 2013, 20 patients underwent laparoscopic cholecystectomy at a single institution. All patients were anesthetized using propofol, remifentanil and rocuronium. FRC was measured automatically by Engstrom Carestation before the abdominal wall lift and again 15 minutes after the start of the procedure. Results: After abdominal wall lift, there was a significant increase in functional residual capacity values (before abdominal wall lift 1.48 × 103 mL, after abdominal wall lift 1.64 × 103 mL (p < 0.0001. No complications such as desaturation were observed in any patient during this study. Conclusions: Laparoscopic surgery with abdominal wall lift may be appropriate for patients who have risk factors such as obesity and respiratory disease.

  3. MHD Effects of a Ferritic Wall on Tokamak Plasmas

    Science.gov (United States)

    Hughes, Paul E.

    It has been recognized for some time that the very high fluence of fast (14.1MeV) neutrons produced by deuterium-tritium fusion will represent a major materials challenge for the development of next-generation fusion energy projects such as a fusion component test facility and demonstration fusion power reactor. The best-understood and most promising solutions presently available are a family of low-activation steels originally developed for use in fission reactors, but the ferromagnetic properties of these steels represent a danger to plasma confinement through enhancement of magnetohydrodynamic instabilities and increased susceptibility to error fields. At present, experimental research into the effects of ferromagnetic materials on MHD stability in toroidal geometry has been confined to demonstrating that it is still possible to operate an advanced tokamak in the presence of ferromagnetic components. In order to better quantify the effects of ferromagnetic materials on tokamak plasma stability, a new ferritic wall has been installated in the High Beta Tokamak---Extended Pulse (HBT-EP) device. The development, assembly, installation, and testing of this wall as a modular upgrade is described, and the effect of the wall on machine performance is characterized. Comparative studies of plasma dynamics with the ferritic wall close-fitting against similar plasmas with the ferritic wall retracted demonstrate substantial effects on plasma stability. Resonant magnetic perturbations (RMPs) are applied, demonstrating a 50% increase in n = 1 plasma response amplitude when the ferritic wall is near the plasma. Susceptibility of plasmas to disruption events increases by a factor of 2 or more with the ferritic wall inserted, as disruptions are observed earlier with greater frequency. Growth rates of external kink instabilities are observed to be twice as large in the presence of a close-fitting ferritic wall. Initial studies are made of the influence of mode rotation frequency

  4. Experimental Investigation of Chatter Dynamics in Thin-walled Tubular Parts Turning

    OpenAIRE

    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...

  5. Fouling in a MBR system with rotating membrane discs

    DEFF Research Database (Denmark)

    Jørgensen, Mads Koustrup; Bentzen, Thomas Ruby; Christensen, Morten Lykkegaard

    concentrations and a clear effluent with no bacteria present in the permeate [1]. However, the process performance is limited by membrane fouling, which results in a lower productivity and higher energy demand and hence places demands for limitation of fouling and/or cleaning of the membranes. One way to do...... uses rotating ceramic membrane discs for creation of shear, which can be changed by controlling the membrane rotation speed of the membrane. Furthermore, the influence of shear on fouling is studied at different radii from the center of rotation, by dividing membranes into different concentric rings......Membrane bioreactors (MBR) are an attractive alternative solution for municipal and industrial wastewater treatment. The MBR, which is a combination of a bioreactor for sludge degradation and a membrane for separation, has the advantages of a low footprint, ability to handle high sludge...

  6. Magnetic domain wall gratings for magnetization reversal tuning and confined dynamic mode localization.

    Science.gov (United States)

    Trützschler, Julia; Sentosun, Kadir; Mozooni, Babak; Mattheis, Roland; McCord, Jeffrey

    2016-08-04

    High density magnetic domain wall gratings are imprinted in ferromagnetic-antiferromagnetic thin films by local ion irradiation by which alternating head-to-tail-to-head-to-tail and head-to-head-to-tail-to-tail spatially overlapping domain wall networks are formed. Unique magnetic domain processes result from the interaction of anchored domain walls. Non-linear magnetization response is introduced by the laterally distributed magnetic anisotropy phases. The locally varying magnetic charge distribution gives rise to localized and guided magnetization spin-wave modes directly constrained by the narrow domain wall cores. The exchange coupled multiphase material structure leads to unprecedented static and locally modified dynamic magnetic material properties.

  7. Nitrate Diffusional Releases from the Saltstone Facility, Vault 2, with Respect to Different Concrete Wall Thicknesses

    International Nuclear Information System (INIS)

    ROBERT, HIERGESELL

    2005-01-01

    To assist the Saltstone Vault 2 Design Team, an investigation was conducted to evaluate the effectiveness of alternative concrete wall thicknesses in limiting nitrate diffusion away from the planned facility. While the current design calls for 18-inch concrete walls, alternative thicknesses of 12-in, 8-in, and 6-in were evaluated using a simplified 1-D numerical model. To serve as a guide for Saltstone Vault 2 conceptual design, the results of this investigation were applied to Saltstone Vault 4 to determine what the hypothetical limits would be for concrete wall thicknesses thinner than the planned 18-inches. This was accomplished by adjusting the Vault 4 Limits, based on the increased nitrate diffusion rates through the thinner concrete walls, such that the 100-m well limit of 44 mg/L of nitrate as nitrate was not exceeded. The implication of these preliminary results is that as thinner vault walls are implemented there is a larger release of nitrate, thus necessitating optimal vault placement to minimize the number of vaults placed along a single groundwater flow path leading to the discharge zone

  8. MHD Mixed Convection Flow in a Rotating Channel in the Presence of an Inclined Magnetic Field with the Hall Effect

    Science.gov (United States)

    Mishra, A.; Sharma, B. K.

    2017-11-01

    A numerical study of an oscillatory unsteady MHD flow and heat and mass transfer in a vertical rotating channel with an inclined uniform magnetic field and the Hall effect is carried out. The conservation equations of momentum, energy, and species are formulated in a rotating frame of reference with inclusion of the buoyancy effects and Lorentz forces. The Lorentz forces are determined by using the generalized Ohm law with the Hall parameter taken into account. The obtained coupled partial differential equations are nondimensionalized and solved numerically by using the explicit finite difference method. The effects of various model parameters, like the Hall parameter, Hartmann number, wall suction/injection parameter, rotation parameter, angle of magnetic field inclination, Prandtl number, Schmidt number, etc., on the channel velocities, skin friction coefficients, Nusselt number, and the Sherwood number are examined. It is found that the influence of the Hartmann number and Hall parameter on the channel velocities and skin friction coefficients is dependent on the value of the wall suction/injection parameter.

  9. Evaluation of cell wall preparations for proteomics: a new procedure for purifying cell walls from Arabidopsis hypocotyls

    Directory of Open Access Journals (Sweden)

    Canut Hervé

    2006-05-01

    Full Text Available Abstract Background The ultimate goal of proteomic analysis of a cell compartment should be the exhaustive identification of resident proteins; excluding proteins from other cell compartments. Reaching such a goal closely depends on the reliability of the isolation procedure for the cell compartment of interest. Plant cell walls possess specific difficulties: (i the lack of a surrounding membrane may result in the loss of cell wall proteins (CWP during the isolation procedure, (ii polysaccharide networks of cellulose, hemicelluloses and pectins form potential traps for contaminants such as intracellular proteins. Several reported procedures to isolate cell walls for proteomic analyses led to the isolation of a high proportion (more than 50% of predicted intracellular proteins. Since isolated cell walls should hold secreted proteins, one can imagine alternative procedures to prepare cell walls containing a lower proportion of contaminant proteins. Results The rationales of several published procedures to isolate cell walls for proteomics were analyzed, with regard to the bioinformatic-predicted subcellular localization of the identified proteins. Critical steps were revealed: (i homogenization in low ionic strength acid buffer to retain CWP, (ii purification through increasing density cushions, (iii extensive washes with a low ionic strength acid buffer to retain CWP while removing as many cytosolic proteins as possible, and (iv absence of detergents. A new procedure was developed to prepare cell walls from etiolated hypocotyls of Arabidopsis thaliana. After salt extraction, a high proportion of proteins predicted to be secreted was released (73%, belonging to the same functional classes as proteins identified using previously described protocols. Finally, removal of intracellular proteins was obtained using detergents, but their amount represented less than 3% in mass of the total protein extract, based on protein quantification. Conclusion The

  10. Mapping Rotational Wavepacket Dynamics with Chirped Probe Pulses

    Science.gov (United States)

    Romanov, Dmitri; Odhner, Johanan; Levis, Robert

    2014-05-01

    We develop an analytical model description of the strong-field pump-probe polarization spectroscopy of rotational transients in molecular gases in a situation when the probe pulse is considerably chirped: the frequency modulation over the pulse duration is comparable with the carrier frequency. In this scenario, a femtosecond pump laser pulse prepares a rotational wavepacket in a gas-phase sample at room temperature. The rotational revivals of the wavepacket are then mapped onto a chirped broadband probe pulse derived from a laser filament. The slow-varying envelope approximation being inapplicable, an alternative approach is proposed which is capable of incorporating the substantial chirp and the related temporal dispersion of refractive indices. Analytical expressions are obtained for the probe signal modulation over the interaction region and for the resulting heterodyned transient birefringence spectra. Dependencies of the outputs on the probe pulse parameters reveal the trade-offs and the ways to optimize the temporal-spectral imaging. The results are in good agreement with the experiments on snapshot imaging of rotational revival patterns in nitrogen gas. We gratefully acknowledge financial support through AFOSR MURI Grant No. FA9550-10-1-0561.

  11. Swimming trajectories of a three-sphere microswimmer near a wall

    Science.gov (United States)

    Daddi-Moussa-Ider, Abdallah; Lisicki, Maciej; Hoell, Christian; Löwen, Hartmut

    2018-04-01

    The hydrodynamic flow field generated by self-propelled active particles and swimming microorganisms is strongly altered by the presence of nearby boundaries in a viscous flow. Using a simple model three-linked sphere swimmer, we show that the swimming trajectories near a no-slip wall reveal various scenarios of motion depending on the initial orientation and the distance separating the swimmer from the wall. We find that the swimmer can either be trapped by the wall, completely escape, or perform an oscillatory gliding motion at a constant mean height above the wall. Using a far-field approximation, we find that, at leading order, the wall-induced correction has a source-dipolar or quadrupolar flow structure where the translational and angular velocities of the swimmer decay as inverse third and fourth powers with distance from the wall, respectively. The resulting equations of motion for the trajectories and the relevant order parameters fully characterize the transition between the states and allow for an accurate description of the swimming behavior near a wall. We demonstrate that the transition between the trapping and oscillatory gliding states is first order discontinuous, whereas the transition between the trapping and escaping states is continuous, characterized by non-trivial scaling exponents of the order parameters. In order to model the circular motion of flagellated bacteria near solid interfaces, we further assume that the spheres can undergo rotational motion around the swimming axis. We show that the general three-dimensional motion can be mapped onto a quasi-two-dimensional representational model by an appropriate redefinition of the order parameters governing the transition between the swimming states.

  12. Faraday's Rotating Wire--The Homopolar Motor: Time to Update?

    Science.gov (United States)

    Auty, Geoff

    2010-01-01

    Answering some of the questions raised in the production of a previous article led to the development of a simple alternative design for the rotating wire demonstration. Significantly, this demonstration avoids the use of mercury as a conducting liquid. The attempt to explain variations in performance of another model and seeking the best…

  13. Considerations on the design of through-wall anchors

    International Nuclear Information System (INIS)

    Ricklefs, Ulf

    2012-01-01

    Connections to existing buildings are often the most difficult planning challenge for the realization of construction measures in case of piping system replacements in nuclear power plants. This is due to restricted space or limited load reserves of the building structure. Usually the realization of support connections to the existing buildings is achieved by anchor bolts. But in critical cases the preferred alternative solution uses through-wall anchors. Up to now uniform assessment thresholds are not available, no technical guidelines or regulations for construction variants exist. Through-wall anchors allow significantly higher load capacities for tensile and shear loads but require enhanced planning and realization efforts.

  14. VMAT optimization with dynamic collimator rotation.

    Science.gov (United States)

    Lyu, Qihui; O'Connor, Daniel; Ruan, Dan; Yu, Victoria; Nguyen, Dan; Sheng, Ke

    2018-04-16

    Although collimator rotation is an optimization variable that can be exploited for dosimetric advantages, existing Volumetric Modulated Arc Therapy (VMAT) optimization uses a fixed collimator angle in each arc and only rotates the collimator between arcs. In this study, we develop a novel integrated optimization method for VMAT, accounting for dynamic collimator angles during the arc motion. Direct Aperture Optimization (DAO) for Dynamic Collimator in VMAT (DC-VMAT) was achieved by adding to the existing dose fidelity objective an anisotropic total variation term for regulating the fluence smoothness, a binary variable for forming simple apertures, and a group sparsity term for controlling collimator rotation. The optimal collimator angle for each beam angle was selected using the Dijkstra's algorithm, where the node costs depend on the estimated fluence map at the current iteration and the edge costs account for the mechanical constraints of multi-leaf collimator (MLC). An alternating optimization strategy was implemented to solve the DAO and collimator angle selection (CAS). Feasibility of DC-VMAT using one full-arc with dynamic collimator rotation was tested on a phantom with two small spherical targets, a brain, a lung and a prostate cancer patient. The plan was compared against a static collimator VMAT (SC-VMAT) plan using three full arcs with 60 degrees of collimator angle separation in patient studies. With the same target coverage, DC-VMAT achieved 20.3% reduction of R50 in the phantom study, and reduced the average max and mean OAR dose by 4.49% and 2.53% of the prescription dose in patient studies, as compared with SC-VMAT. The collimator rotation co-ordinated with the gantry rotation in DC-VMAT plans for deliverability. There were 13 beam angles in the single-arc DC-VMAT plan in patient studies that requires slower gantry rotation to accommodate multiple collimator angles. The novel DC-VMAT approach utilizes the dynamic collimator rotation during arc

  15. Roofbolters with compressed-air rotators

    Science.gov (United States)

    Lantsevich, MA; Repin Klishin, AA, VI; Kokoulin, DI

    2018-03-01

    The specifications of the most popular roofbolters of domestic and foreign manufacture currently in operation in coal mines are discussed. Compressed-air roofbolters SAP and SAP2 designed at the Institute of Mining are capable of drilling in hard rocks. The authors describe the compressed-air rotator of SAP2 roofbolter with alternate motion rotors. From the comparative analysis of characteristics of SAP and SAP 2 roofbolters, the combination of high-frequency axial and rotary impacts on a drilling tool in SAP2 ensure efficient drilling in rocks with the strength up to 160 MPa.

  16. Mixing on a spherical shell by cutting and shuffling with non-orthogonal rotation axes

    Science.gov (United States)

    Lynn, Thomas; Umbanhowar, Paul; Ottino, Julio; Lueptow, Richard

    2017-11-01

    We examine a dynamical system that models the mixing of granular material in a half-filled spherical tumbler rotated about two horizontal alternating axes by using the machinery of cutting and shuffling through piecewise-isometries (PWI). Previous restrictions on how the domain is cut and shuffled are relaxed to allow non-orthogonal axes of rotation. Mixing is not only dependent on the amount of rotation used to induce mixing, but also on the relative orientation of the rotation axes. Well mixed regions within the PWI, which have a high density of cuts, typically interact with the periodic cutting boundary for both rotation axes. However, there are parameter combinations where the two rotations cut distinctly separate regions. The three-parameter space (a rotation about each axis and the relative orientation of the axes) is rich with detailed mixing features such as fractal boundaries and elliptic-like non-mixing regions. Supported by National Science Foundation Grant No. CMMI-1435065.

  17. Wave-driven Rotation in Supersonically Rotating Mirrors

    Energy Technology Data Exchange (ETDEWEB)

    A. Fetterman and N.J. Fisch

    2010-02-15

    Supersonic rotation in mirrors may be produced by radio frequency waves. The waves produce coupled diffusion in ion kinetic and potential energy. A population inversion along the diffusion path then produces rotation. Waves may be designed to exploit a natural kinetic energy source or may provide the rotation energy on their own. Centrifugal traps for fusion and isotope separation may benefit from this wave-driven rotation.

  18. Wave-driven Rotation in Supersonically Rotating Mirrors

    International Nuclear Information System (INIS)

    Fetterman, A.; Fisch, N.J.

    2010-01-01

    Supersonic rotation in mirrors may be produced by radio frequency waves. The waves produce coupled diffusion in ion kinetic and potential energy. A population inversion along the diffusion path then produces rotation. Waves may be designed to exploit a natural kinetic energy source or may provide the rotation energy on their own. Centrifugal traps for fusion and isotope separation may benefit from this wave-driven rotation.

  19. Partial rotational lattice order–disorder in stefin B crystals

    International Nuclear Information System (INIS)

    Renko, Miha; Taler-Verčič, Ajda; Mihelič, Marko; Žerovnik, Eva; Turk, Dušan

    2014-01-01

    Crystal lattice disorders are a phenomenon which may hamper the determination of macromolecular crystal structures. Using the case of the crystal structure of stefin B, identification of rotational order–disorder and structure determination are described. At present, the determination of crystal structures from data that have been acquired from twinned crystals is routine; however, with the increasing number of crystal structures additional crystal lattice disorders are being discovered. Here, a previously undescribed partial rotational order–disorder that has been observed in crystals of stefin B is described. The diffraction images revealed normal diffraction patterns that result from a regular crystal lattice. The data could be processed in space groups I4 and I422, yet one crystal exhibited a notable rejection rate in the higher symmetry space group. An explanation for this behaviour was found once the crystal structures had been solved and refined and the electron-density maps had been inspected. The lattice of stefin B crystals is composed of five tetramer layers: four well ordered layers which are followed by an additional layer of alternatively placed tetramers. The presence of alternative positions was revealed by the inspection of electron-density score maps. The well ordered layers correspond to the crystal symmetry of space group I422. In addition, the positions of the molecules in the additional layer are related by twofold rotational axes which correspond to space group I422; however, these molecules lie on the twofold axis and can only be related in a statistical manner. When the occupancies of alternate positions and overlapping are equal, the crystal lattice indeed fulfills the criteria of space group I422; when these occupancies are not equal, the lattice only fulfills the criteria of space group I4

  20. Feedback suppression of rotating external kink instabilities in the presence of noise

    International Nuclear Information System (INIS)

    Hanson, Jeremy M.; De Bono, Bryan; James, Royce W.; Levesque, Jeffrey P.; Mauel, Michael E.; Maurer, David A.; Navratil, Gerald A.; Pedersen, Thomas Sunn; Shiraki, Daisuke

    2008-01-01

    The authors report on the first experimental demonstration of active feedback suppression of rotating external kink modes near the ideal wall limit in a tokamak using Kalman filtering to discriminate the n=1 kink mode from background noise. The Kalman filter contains an internal model that captures the dynamics of a rotating, growing n=1 mode. Suppression of the external kink mode is demonstrated over a broad range of phase angles between the sensed mode and applied control field, and performance is robust at noise levels that render proportional gain feedback ineffective. Suppression of the kink mode is accomplished without excitation of higher frequencies as was observed in previous experiments using lead-lag loop compensation [A. J. Klein et al., Phys Plasmas 12, 040703 (2005)

  1. Uncovering the cognitive processes underlying mental rotation: an eye-movement study.

    Science.gov (United States)

    Xue, Jiguo; Li, Chunyong; Quan, Cheng; Lu, Yiming; Yue, Jingwei; Zhang, Chenggang

    2017-08-30

    Mental rotation is an important paradigm for spatial ability. Mental-rotation tasks are assumed to involve five or three sequential cognitive-processing states, though this has not been demonstrated experimentally. Here, we investigated how processing states alternate during mental-rotation tasks. Inference was carried out using an advanced statistical modelling and data-driven approach - a discriminative hidden Markov model (dHMM) trained using eye-movement data obtained from an experiment consisting of two different strategies: (I) mentally rotate the right-side figure to be aligned with the left-side figure and (II) mentally rotate the left-side figure to be aligned with the right-side figure. Eye movements were found to contain the necessary information for determining the processing strategy, and the dHMM that best fit our data segmented the mental-rotation process into three hidden states, which we termed encoding and searching, comparison, and searching on one-side pair. Additionally, we applied three classification methods, logistic regression, support vector model and dHMM, of which dHMM predicted the strategies with the highest accuracy (76.8%). Our study did confirm that there are differences in processing states between these two of mental-rotation strategies, and were consistent with the previous suggestion that mental rotation is discrete process that is accomplished in a piecemeal fashion.

  2. Rotating flow

    CERN Document Server

    Childs, Peter R N

    2010-01-01

    Rotating flow is critically important across a wide range of scientific, engineering and product applications, providing design and modeling capability for diverse products such as jet engines, pumps and vacuum cleaners, as well as geophysical flows. Developed over the course of 20 years' research into rotating fluids and associated heat transfer at the University of Sussex Thermo-Fluid Mechanics Research Centre (TFMRC), Rotating Flow is an indispensable reference and resource for all those working within the gas turbine and rotating machinery industries. Traditional fluid and flow dynamics titles offer the essential background but generally include very sparse coverage of rotating flows-which is where this book comes in. Beginning with an accessible introduction to rotating flow, recognized expert Peter Childs takes you through fundamental equations, vorticity and vortices, rotating disc flow, flow around rotating cylinders and flow in rotating cavities, with an introduction to atmospheric and oceanic circul...

  3. Rotational seismology

    Science.gov (United States)

    Lee, William H K.

    2016-01-01

    Rotational seismology is an emerging study of all aspects of rotational motions induced by earthquakes, explosions, and ambient vibrations. It is of interest to several disciplines, including seismology, earthquake engineering, geodesy, and earth-based detection of Einstein’s gravitation waves.Rotational effects of seismic waves, together with rotations caused by soil–structure interaction, have been observed for centuries (e.g., rotated chimneys, monuments, and tombstones). Figure 1a shows the rotated monument to George Inglis observed after the 1897 Great Shillong earthquake. This monument had the form of an obelisk rising over 19 metres high from a 4 metre base. During the earthquake, the top part broke off and the remnant of some 6 metres rotated about 15° relative to the base. The study of rotational seismology began only recently when sensitive rotational sensors became available due to advances in aeronautical and astronomical instrumentations.

  4. Rotational order–disorder structure of fluorescent protein FP480

    International Nuclear Information System (INIS)

    Pletnev, Sergei; Morozova, Kateryna S.; Verkhusha, Vladislav V.; Dauter, Zbigniew

    2009-01-01

    An analysis of the rotational order–disorder structure of fluorescent protein FP480 is presented. In the last decade, advances in instrumentation and software development have made crystallography a powerful tool in structural biology. Using this method, structural information can now be acquired from pathological crystals that would have been abandoned in earlier times. In this paper, the order–disorder (OD) structure of fluorescent protein FP480 is discussed. The structure is composed of tetramers with 222 symmetry incorporated into the lattice in two different ways, namely rotated 90° with respect to each other around the crystal c axis, with tetramer axes coincident with crystallographic twofold axes. The random distribution of alternatively oriented tetramers in the crystal creates a rotational OD structure with statistically averaged I422 symmetry, although the presence of very weak and diffuse additional reflections suggests that the randomness is only approximate

  5. Current-driven vortex domain wall motion in wire-tube nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Espejo, A. P. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); Institute of Nanostructure and Solid State Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg (Germany); Vidal-Silva, N. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); López-López, J. A. [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Goerlitz, D.; Nielsch, K. [Institute of Nanostructure and Solid State Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg (Germany); Escrig, J. [Departamento de Física, Universidad de Santiago de Chile (USACH), Av. Ecuador 3493, 9170124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Av. Ecuador 3493, 9170124 Santiago (Chile)

    2015-03-30

    We have investigated the current-driven domain wall motion in nanostructures comprised of a pair of nanotube and nanowire segments. Under certain values of external magnetic fields, it is possible to pin a vortex domain wall in the transition zone between the wire and tube segments. We explored the behavior of this domain wall under the action of an electron flow applied in the opposite direction to the magnetic field. Thus, for a fixed magnetic field, it is possible to release a domain wall pinned simply by increasing the intensity of the current density, or conversely, for a fixed current density, it is possible to release the domain wall simply decreasing the magnetic external field. When the domain wall remains pinned due to the competition between the current density and the magnetic external field, it exhibits a oscillation frequency close to 8 GHz. The amplitude of the oscillations increases with the current density and decreases over time. On the other hand, when the domain wall is released and propagated through the tube segment, this shows the standard separation between a steady and a precessional regime. The ability to pin and release a domain wall by varying the geometric parameters, the current density, or the magnetic field transforms these wire-tube nanostructures in an interesting alternative as an on/off switch nano-transistor.

  6. Medial Entorhinal Grid Cells and Head Direction Cells Rotate with a T-Maze More Often During Less Recently Experienced Rotations

    Science.gov (United States)

    Gupta, Kishan; Beer, Nathan J.; Keller, Lauren A.; Hasselmo, Michael E.

    2014-01-01

    Prior studies of head direction (HD) cells indicate strong landmark control over the preferred firing direction of these cells, with few studies exhibiting shifts away from local reference frames over time. We recorded spiking activity of grid and HD cells in the medial entorhinal cortex of rats, testing correlations of local environmental cues with the spatial tuning curves of these cells' firing fields as animals performed continuous spatial alternation on a T-maze that shared the boundaries of an open-field arena. The environment was rotated into configurations the animal had either seen or not seen in the past recording week. Tuning curves of both cell types demonstrated commensurate shifts of tuning with T-maze rotations during less recent rotations, more so than recent rotations. This strongly suggests that animals are shifting their reference frame away from the local environmental cues over time, learning to use a different reference frame more likely reliant on distal or idiothetic cues. In addition, grid fields demonstrated varying levels of “fragmentation” on the T-maze. The propensity for fragmentation does not depend on grid spacing and grid score, nor animal trajectory, indicating the cognitive treatment of environmental subcompartments is likely driven by task demands. PMID:23382518

  7. Degenerated shell element for geometrically nonlinear analysis of thin-walled piezoelectric active structures

    International Nuclear Information System (INIS)

    Marinković, D; Köppe, H; Gabbert, U

    2008-01-01

    Active piezoelectric thin-walled structures, especially those with a notably higher membrane than bending stiffness, are susceptible to large rotations and transverse deflections. Recent investigations conducted by a number of researchers have shown that the predicted behavior of piezoelectric structures can be significantly influenced by the assumption of large displacements and rotations of the structure, thus demanding a geometrically nonlinear formulation in order to investigate it. This paper offers a degenerated shell element and a simplified formulation that relies on small incremental steps for the geometrically nonlinear analysis of piezoelectric composite structures. A set of purely mechanical static cases is followed by a set of piezoelectric coupled static cases, both demonstrating the applicability of the proposed formulation

  8. Faraday rotation in multiple quantum wells of GaAs/AlGaAs

    International Nuclear Information System (INIS)

    Dudziak, E.; Bozym, J.; Prochnik, D.; Wasilewski, Z.R.

    1996-01-01

    We report on the results of first measurements on the Faraday rotation of modulated n-doped multiple quantum wells of GaAs/Al x Ga 1-x As (x = 0.312). The measurements have been performed in the magnetic fields up to 13 T at the temperature of 2 K, in the spectral region of interband transitions. A rich structure of magneto-excitons has been found in the measured spectra. Faraday rotation (phase) measurements are proposed as an alternative method to the photoluminescence excitation for investigations of magneto-excitons in quantum wells. The dependence of measured Faraday rotation on magnetic field and hypothetical connections with quantum Hall effect are also discussed. (author)

  9. Geometric Control Over the Motion of Magnetic Domain Walls

    International Nuclear Information System (INIS)

    N.A. Sinitsyn; V.V. Dobrovitski; S. urazhdin; Avadh Saxena

    2008-01-01

    We propose a method that enables a precise control of magnetic patterns and relies only on the fundamental properties of the wire as well as on the choice of the path in the controlled parameter space but not on the rate of motion along this path. Possible experimental realizations of this mechanism are discussed. In particular, we show that the domain walls in magnetic nanowires can be translated by rotation of the magnetic easy axis or by applying pulses of magnetic field directed transverse to the magnetic easy axis

  10. Contribution of Legume Rotations to the Nitrogen Requirements of a ...

    African Journals Online (AJOL)

    Industrial fertilizers are expensive for small-scale farmers who, as alternative, rely on legume crops for providing N for a subsequent maize crop. A legume-maize rotational experiment was carried out on a Rhodic Ferralsol at Mlingano Agricultural Research Institute in Muheza, Tanga, Tanzania, to evaluate the effects of ...

  11. Beregnede fugtforhold i konstruktioner:Del af "Varme- og fugttekniske undersøgelser af alternative isoelringsmaterialer"

    OpenAIRE

    Rode, Carsten; Rasmussen, Niels T.

    1999-01-01

    Calculated Moisture Conditions in Building Constructions. Part of "Hygrothermal Properties of Alternative Insulation Materials".The hygrothermal performance of constructions with alternative insulation products has been analysed with the 1-dimensional computer model MATCH for combined heat and moisture transfer. The analysis concerns both traditional wall and roof constructions with the alternative insulation products, and some alternative designs prescribed by manufacturers of alternative in...

  12. The Taylor-Proudman column in a rapidly-rotating compressible fluid I. energy transports

    International Nuclear Information System (INIS)

    Park, Jun Sang

    2014-01-01

    A theoretical study is made of the steady flow of a compressible fluid in a rapidly rotating finite cylinder. Flow is generated by imposing mechanical and/or thermal disturbances at the rotating endwall disks. Both the Ekman and Rossby numbers are small. An examination is made of the energy budget for a control volume in the Ekman boundary layer. A combination of physical variables, which is termed the energy flux content, consisting of temperature and modified angular momentum, emerges to be relevant. The distinguishing features of a compressible fluid, in contrast to those of an incompressible fluid, are noted. A plausible argument is given to explain the difficulty in achieving the Taylor-Proudman column in a compressible rotating fluid. For the Taylor-Proudman column to be sustained, in the interior, it is shown that the net energy transport between the solid disk wall and the interior fluid should vanish. Physical rationalizations are facilitated by resorting to the concept of the afore-stated energy flux content.

  13. Lattice gas automaton scheme with stochastic particle movement for a rotated fluid flow

    International Nuclear Information System (INIS)

    Ishiguro, Misako

    2002-01-01

    Lattice gas automaton (LGA) models developed so far are just for Cartesian geometries, and no direct approach to rotated fluid flows is found. In this paper, LGA method is applied to model a two-dimensional rotated flow. Several problems specific to the rotated flow are to be solved: hexagonal lattice geometry to effectively identify the neighbors, boundary condition for irregular walls, multi-speed scheme to represent angular-oriented fluid velocity υ θ ≅γω, shape of macroscopic domain for statistics, formula to obtain macroscopic quantities such as density and mean fluid velocities, application method of Fermi-Dirac function to the initial particle arrangement. For this purpose, FHP-I type hexagonal lattice model is revised and a new LGA model with stochastic particle movement is proposed. The results of the trial calculation are shown. It is also investigated whether or not the underlying microscopic Boolean equations newly introduced leads to Navier-Stokes equation. (author)

  14. Surface-micromachined rotatable member having a low-contact-area hub

    Science.gov (United States)

    Rodgers, M. Steven; Sniegowski, Jeffry J.; Krygowski, Thomas W.

    2003-11-18

    A surface-micromachined rotatable member formed on a substrate and a method for manufacturing thereof are disclosed. The surface-micromachined rotatable member, which can be a gear or a rotary stage, has a central hub, and an annulus connected to the central hub by an overarching bridge. The hub includes a stationary axle support attached to the substrate and surrounding an axle. The axle is retained within the axle support with an air-gap spacing therebetween of generally 0.3 .mu.m or less. The rotatable member can be formed by alternately depositing and patterning layers of a semiconductor (e.g. polysilicon or a silicon-germanium alloy) and a sacrificial material and then removing the sacrificial material, at least in part. The present invention has applications for forming micromechanical or microelectromechanical devices requiring lower actuation forces, and providing improved reliability.

  15. Surface--micromachined rotatable member having a low-contact-area hub

    Science.gov (United States)

    Rodgers, M. Steven; Sniegowski, Jeffry J.

    2002-01-01

    A surface-micromachined rotatable member formed on a substrate and a method for manufacturing thereof are disclosed. The surface-micromachined rotatable member, which can be a gear or a rotary stage, has a central hub, and an annulus connected to the central hub by an overarching bridge. The hub includes a stationary axle support attached to the substrate and surrounding an axle. The axle is retained within the axle support with an air-gap spacing therebetween of generally 0.3 .mu.m or less. The rotatable member can be formed by alternately depositing and patterning layers of a semiconductor (e.g. polysilicon or a silicon-germanium alloy) and a sacrificial material and then removing the sacrificial material, at least in part. The present invention has applications for forming micromechanical or microelectromechanical devices requiring lower actuation forces, and providing improved reliability.

  16. Estimating adipose tissue in the chest wall using ultrasonic and alternate 40K and biometric measurements

    International Nuclear Information System (INIS)

    Anderson, A.L.; Campbell, G.W.

    1982-01-01

    The percentage of adipose (fat) tissue in the chest wall must be known to accurately measure Pu in the human lung. Correction factors of 100% or more in x-ray detection efficiency are common. Methods using simple 40 K and biometric measurement techniques were investigated to determine the adipose content in the human chest wall. These methods predict adipose content to within 15% of the absolute ultrasonic value. These new methods are discussed and compared with conventional ultrasonic measurement techniques

  17. Development of Disk Rover, wall-climbing robot using permanent magnet disk

    International Nuclear Information System (INIS)

    Hirose, Shigeo; Tsutsumitake; Hiroshi; Toyama, Ryousei; Kobayashi, Kengo.

    1992-01-01

    A new type of wall climbing robot, named Disk Rover, using permanent magnet disks are developed. The newly introduced permanent magnet disk is to rotate the magnet disk on the surface of wall with partly contacted posture. It allows to produce high magnetic attraction force compared with conventional permanent wheel which utilizes only a small portion of the magnet installed around the wheel. The optimum design of the magnetic wheel is done by using finit element method and it is shown that the magnetic attraction force vs. weight ratio can be designed about three times higher than conventional type magnet wheel. The developed Disk Rover is 25 kg in weight including controller and battery, about 685 mm in diameter, 239 mm in height and has a pair of permanent magnet disks. It is demonstrated by the experiments that the Disk Rover can move around on the surface of the wall quite smoothly by radio control and has payload of about its own weight. Several considerations are also done in order to surmount bead weld. (author)

  18. Efeito do pastejo rotacionado e alternado com bovinos adultos no controle da verminose em ovelhas Effect of rotational and alternate grazing with adult cattle on the control of nematode parasites in sheep

    Directory of Open Access Journals (Sweden)

    L.H. Fernandes

    2004-12-01

    Full Text Available Estudaram-se os efeitos do pastejo alternado de ovinos e bovinos e do pastejo rotacionado sobre o controle da verminose em ovelhas. Utilizou-se uma área experimental composta por três módulos de 1,67ha cada. Os módulos foram subdivididos em oito piquetes. Vinte ovelhas foram colocadas no módulo 1 e quatro bovinos adultos no módulo 2. Os animais permaneceram em cada piquete do módulo por cinco dias, totalizando 40 dias de permanência em cada módulo. Ao final desse período, as ovelhas foram transferidas para o módulo onde estavam os bovinos e estes para o módulo onde estavam os ovinos, mantendo esse esquema até o final do experimento. Um grupo-controle de 20 ovelhas foi mantido, também em sistema rotacionado, em um terceiro módulo, sem compartilhar a pastagem. As ovelhas submetidas ao manejo com bovinos apresentaram o menor grau de infecção por nematódeos gastrintestinais e os maiores valores de volume globular. O pastejo rotacionado de ovinos, sem a utilização de bovinos, não foi eficiente no controle da verminose das ovelhas. A utilização do pastejo rotacionado e alternado de ovinos e bovinos adultos exerceu efeito benéfico significativo no controle da verminose ovina.The effects of rotational and alternate grazing involving cattle and sheep on the control of nematode parasites in sheep were evaluated. Three areas with 1.67ha were subdivided into eight paddocks each. Twenty ewes and four cattle were allotted to areas 1 and 2, respectively. They grazed during five days in each of eight paddocks of each area. The sheep and cattle rotated in each area for 40 days. At the end of this period, ewes were transferred to the area where cattle were previously kept and these animals were transferred to the area where sheep had previously grazed. This arrangement was kept until the end of the experiment. A control group with 20 ewes rotated in the third area, also with eight paddocks. Ewes that alternately grazed with cattle showed

  19. Opening of through-wall cracks in BWR coolant lines due to the application of severe overloads II: a simple approach

    International Nuclear Information System (INIS)

    Smith, E.

    1984-01-01

    A simple theoretical analysis gives an estimate of the opening area associated with a through-wall crack in a pipe when this is subject to an imposed rotation at its ends. The crack-opening area is expressed in terms of the crack size, and the plastic rotation at the cracked cross-section, where plastic deformation is assumed to be confined. The results are relevant to the integrity of boiling water reactor coolant systems during accident conditions

  20. Observational properties of rigidly rotating dust configurations

    Energy Technology Data Exchange (ETDEWEB)

    Ilyas, Batyr; Malafarina, Daniele [Nazarbayev University, Department of Physics, Astana (Kazakhstan); Yang, Jinye [Fudan University, Center for Field Theory and Particle Physics and Department of Physics, Shanghai (China); Bambi, Cosimo [Fudan University, Center for Field Theory and Particle Physics and Department of Physics, Shanghai (China); Eberhard-Karls Universitaet Tuebingen, Theoretical Astrophysics, Tuebingen (Germany)

    2017-07-15

    We study the observational properties of a class of exact solutions of Einstein's field equations describing stationary, axially symmetric, rigidly rotating dust (i.e. non-interacting particles). We ask the question whether such solutions can describe astrophysical rotating dark matter clouds near the center of galaxies and we probe the possibility that they may constitute an alternative to supermassive black holes at the center of galaxies. We show that light emission from accretion disks made of ordinary baryonic matter in this space-time has several differences with respect to the emission of light from similar accretion disks around black holes. The shape of the iron Kα line in the reflection spectrum of accretion disks can potentially distinguish this class of solutions from the Kerr metric, but this may not be possible with current X-ray missions. (orig.)

  1. Resistive wall tearing mode generated finite net electromagnetic torque in a static plasma

    International Nuclear Information System (INIS)

    Hao, G. Z.; Wang, A. K.; Xu, M.; Qu, H. P.; Peng, X. D.; Wang, Z. H.; Xu, J. Q.; Qiu, X. M.; Liu, Y. Q.

    2014-01-01

    The MARS-F code [Y. Q. Liu et al., Phys. Plasmas 7, 3681 (2000)] is applied to numerically investigate the effect of the plasma pressure on the tearing mode stability as well as the tearing mode-induced electromagnetic torque, in the presence of a resistive wall. The tearing mode with a complex eigenvalue, resulted from the favorable averaged curvature effect [A. H. Glasser et al., Phys. Fluids 18, 875 (1975)], leads to a re-distribution of the electromagnetic torque with multiple peaking in the immediate vicinity of the resistive layer. The multiple peaking is often caused by the sound wave resonances. In the presence of a resistive wall surrounding the plasma, a rotating tearing mode can generate a finite net electromagnetic torque acting on the static plasma column. Meanwhile, an equal but opposite torque is generated in the resistive wall, thus conserving the total momentum of the whole plasma-wall system. The direction of the net torque on the plasma is always opposite to the real frequency of the mode, agreeing with the analytic result by Pustovitov [Nucl. Fusion 47, 1583 (2007)]. When the wall time is close to the oscillating time of the tearing mode, the finite net torque reaches its maximum. Without wall or with an ideal wall, no net torque on the static plasma is generated by the tearing mode. However, re-distribution of the torque density in the resistive layer still occurs

  2. ROTATING BULLETS FROM A VARIABLE PROTOSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xuepeng [Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008 (China); Arce, Héctor G. [Department of Astronomy, Yale University, Box 208101, New Haven, CT 06520-8101 (United States); Zhang, Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Launhardt, Ralf; Henning, Thomas, E-mail: xpchen@pmo.ac.cn [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)

    2016-06-20

    We present Submillimeter Array (SMA) CO (2–1) observations toward the protostellar jet driven by SVS 13 A, a variable protostar in the NGC 1333 star-forming region. The SMA CO (2–1) images show an extremely high-velocity jet composed of a series of molecular “bullets.” Based on the SMA CO observations, we discover clear and large systematic velocity gradients, perpendicular to the jet axis, in the blueshifted and redshifted bullets. After discussing several alternative interpretations, such as twin-jets, jet precession, warped disk, and internal helical shock, we suggest that the systematic velocity gradients observed in the bullets result from the rotation of the SVS 13 A jet. From the SMA CO images, the measured rotation velocities are 11.7–13.7 km s{sup −1} for the blueshifted bullet and 4.7 ± 0.5 km s{sup −1} for the redshifted bullet. The estimated specific angular momenta of the two bullets are comparable to those of dense cores, about 10 times larger than those of protostellar envelopes, and about 20 times larger than those of circumstellar disks. If the velocity gradients are due to the rotation of the SVS 13 A jet, the significant amount of specific angular momenta of the bullets indicates that the rotation of jets/outflows is a key mechanism to resolve the so-called “angular momentum problem” in the field of star formation. The kinematics of the bullets suggests that the jet launching footprint on the disk has a radius of ∼7.2–7.7 au, which appears to support the extended disk-wind model. We note that further observations are needed to comprehensively understand the kinematics of the SVS 13 A jet, in order to confirm the rotation nature of the bullets.

  3. Free-Boundary 3D Equilibria and Resistive Wall Instabilities with Extended-MHD

    Science.gov (United States)

    Ferraro, N. M.

    2015-11-01

    The interaction of the plasma with external currents, either imposed or induced, is a critical element of a wide range of important tokamak phenomena, including resistive wall mode (RWM) stability and feedback control, island penetration and locking, and disruptions. A model of these currents may be included within the domain of extended-MHD codes in a way that preserves the self-consistency, scalability, and implicitness of their numerical methods. Such a model of the resistive wall and non-axisymmetric coils is demonstrated using the M3D-C1 code for a variety of applications, including RWMs, perturbed non-axisymmetric equilibria, and a vertical displacement event (VDE) disruption. The calculated free-boundary equilibria, which include Spitzer resistivity, rotation, and two-fluid effects, are compared to external magnetic and internal thermal measurements for several DIII-D discharges. In calculations of the perturbed equilibria in ELM suppressed discharges, the tearing response at the top of the pedestal is found to correlate with the onset of ELM suppression. Nonlinear VDE calculations, initialized using a vertically unstable DIII-D equilibrium, resolve in both space and time the currents induced in the wall and on the plasma surface, and also the currents flowing between the plasma and the wall. The relative magnitude of these contributions and the total impulse to the wall depend on the resistive wall time, although the maximum axisymmetric force on the wall over the course of the VDE is found to be essentially independent of the wall conductivity. This research was supported by US DOE contracts DE-FG02-95ER54309, DE-FC02-04ER54698 and DE-AC52-07NA27344.

  4. Identification of dominant flow structures in rapidly rotating convection of liquid metals using Dynamic Mode Decomposition

    Science.gov (United States)

    Horn, S.; Schmid, P. J.; Aurnou, J. M.

    2016-12-01

    The Earth's metal core acts as a dynamo whose efficiency in generating and maintaining the magnetic field is essentially determined by the rotation rate and the convective motions occurring in its outer liquid part. For the description of the primary physics in the outer core the idealized system of rotating Rayleigh-Bénard convection is often invoked, with the majority of studies considering only working fluids with Prandtl numbers of Pr ≳ 1. However, liquid metals are characterized by distinctly smaller Prandtl numbers which in turn result in an inherently different type of convection. Here, we will present results from direct numerical simulations of rapidly rotating convection in a fluid with Pr ≈ 0.025 in cylindrical containers and Ekman numbers as low as 5 × 10-6. In this system, the Coriolis force is the source of two types of inertial modes, the so-called wall modes, that also exist at moderate Prandtl numbers, and cylinder-filling oscillatory modes, that are a unique feature of small Prandtl number convection. The obtained flow fields were analyzed using the Dynamic Mode Decomposition (DMD). This technique allows to extract and identify the structures that govern the dynamics of the system as well as their corresponding frequencies. We have investigated both the regime where the flow is purely oscillatory and the regime where wall modes and oscillatory modes co-exist. In the purely oscillatory regime, high and low frequency oscillatory modes characterize the flow. When both types of modes are present, the DMD reveals that the wall-attached modes dominate the flow dynamics. They precess with a relatively low frequency in retrograde direction. Nonetheless, also in this case, high frequency oscillations have a significant contribution.

  5. 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

  6. Translational, rotational, vibrational and electron temperatures of a gliding arc discharge

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Ehn, Andreas; Gao, Jinlong

    2017-01-01

    , 0) band was used to simulate the rotational temperature (Tr) of the gliding arc discharge whereas the NO A–X (1, 0) and (0, 1) bands were used to determine its vibrational temperature (Tv). The instantaneous reduced electric field strength E/N was obtained by simultaneously measuring......Translational, rotational, vibrational and electron temperatures of a gliding arc discharge in atmospheric pressure air were experimentally investigated using in situ, non-intrusive optical diagnostic techniques. The gliding arc discharge was driven by a 35 kHz alternating current (AC) power source...... and operated in a glow-type regime. The two-dimensional distribution of the translational temperature (Tt) of the gliding arc discharge was determined using planar laser-induced Rayleigh scattering. The rotational and vibrational temperatures were obtained by simulating the experimental spectra. The OH A–X (0...

  7. On the motion of a compressible fluid in a rotating cylinder

    International Nuclear Information System (INIS)

    Brouwers, J.J.H.

    1976-06-01

    The secondary flow of an incompressible fluid or a perfect gas in a rotating cylinder is taken as a small perturbation on the isothermal state of rigid body rotation. Three types of flow are identified by increasing length-to-radius ratio L. These correspond to Esup(1/2) -1 and E -1 approximately L, where E is the Ekman number based on the radius and taken to be small. In the first range a geostrophic flow in the interior extended by Ekman layers near the end caps and Stewartson layers near the cylinder wall is found. For L approximately Esup(-1/2) and L approximately E -1 both Stewartson layers successively expand to the interior. For L approximately> E -1 radial diffusion of momentum is an important parameter describing the flow in the main section of the cylinder. For the perfect gas, special attention is focussed on strong radial density gradients. The modified Ekman number Esub(m) based on the density at the cylinder wall and on the density scale height is taken to be small. Increasing the ratio of the length to the radial density scale height Lsub(m) again three types of flow are distinguished. These correspond to Esub(m)sup(1/2) -1 and Esub(m)sup(-1) approximately Lsub(m). Compared to the incompressible fluid, two essential differences are found. (i) An inviscid flow characteristic for the first range is only observed in a limited region near the cylinder wall. Diffusive processes are important in the core of the cylinder. (ii) A change of the flow type appears when both Stewartson layers successively expand over the small radial density scale height. Diffusive regions come up from the centre of the cylinder and join. A change of the flow type appears at relatively small values of L. The theory discusses the efficiency of gas ultracentrifuges for isotope separation

  8. Global rotation

    International Nuclear Information System (INIS)

    Rosquist, K.

    1980-01-01

    Global rotation in cosmological models is defined on an observational basis. A theorem is proved saying that, for rigid motion, the global rotation is equal to the ordinary local vorticity. The global rotation is calculated in the space-time homogeneous class III models, with Godel's model as a special case. It is shown that, with the exception of Godel's model, the rotation in these models becomes infinite for finite affine parameter values. In some directions the rotation changes sign and becomes infinite in a direction opposite to the local vorticity. The points of infinite rotation are identified as conjugate points along the null geodesics. The physical interpretation of the infinite rotation is discussed, and a comparison with the behaviour of the area distance at conjugate points is given. (author)

  9. Generalized uncertainty principle and entropy of three-dimensional rotating acoustic black hole

    International Nuclear Information System (INIS)

    Zhao, HuiHua; Li, GuangLiang; Zhang, LiChun

    2012-01-01

    Using the new equation of state density from the generalized uncertainty principle, we investigate statistics entropy of a 3-dimensional rotating acoustic black hole. When λ introduced in the generalized uncertainty principle takes a specific value, we obtain an area entropy and a correction term associated with the acoustic black hole. In this method, there does not exist any divergence and one needs not the small mass approximation in the original brick-wall model. -- Highlights: ► Statistics entropy of a 3-dimensional rotating acoustic black hole is studied. ► We obtain an area entropy and a correction term associated with it. ► We make λ introduced in the generalized uncertainty principle take a specific value. ► There does not exist any divergence in this method.

  10. A PHOTON-DOMINATED REGION MODEL FOR THE FIR MID-J CO LADDER WITH UNIVERSAL ROTATIONAL TEMPERATURE IN STAR FORMING REGIONS

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seokho; Park, Yong-Sun [Astronomy Program, Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Lee, Jeong-Eun [Department of Astronomy and Space Science, Kyung Hee University, Yongin-shi, Kyungki-do 449-701 (Korea, Republic of); Bergin, Edwin A., E-mail: shlee@astro.snu.ac.kr [Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States)

    2014-08-01

    A photon-dominated region (PDR) is one of the leading candidate mechanisms for the origin of warm CO gas with near universal ∼300 K rotational temperature inferred from the CO emission detected toward embedded protostars by Herschel/PACS. We have developed a PDR model in general coordinates, where we can use the most adequate coordinate system for an embedded protostar having outflow cavity walls, to solve chemistry and gas energetics self-consistently for given UV radiation fields with different spectral shapes. Simple one-dimensional tests and applications show that FIR mid-J (14 ≤ J ≤ 24) CO lines are emitted from close to the surface of a dense region exposed to high UV fluxes. We apply our model to HH46 and find that the UV-heated outflow cavity wall can reproduce the mid-J CO transitions observed by Herschel/PACS. A model with UV radiation corresponding to a blackbody of 10,000 K results in a rotational temperature lower than 300 K, while models with the Draine interstellar radiation field and the 15,000 K blackbody radiation field predict a rotational temperature similar to the observed one.

  11. Development of Vmax III. Magnetic wall climbing robot with holonomic and omni-directional mobility

    International Nuclear Information System (INIS)

    Tsuru, Kiyoshi; Hirose, Shigeo

    2012-01-01

    Wall-climbing robots having holonomic and omni-directional mobility would enhance the manipulation performance of the mounted arm and enable it to execute various tasks on the surface of large structures. This study focuses on the wall-climbing robots having permanent magnet attractive units to stick to the surface of iron structure such as atomic reactors and discuss the development of a specific holonomic and omni-directional wall-climbing mechanisms. Basic driving mechanism of the wall-climbing robot is based on our former invention named Omni Disk which consists of multiple rollers attached to one side of a rotating disk and having a mechanism to direct the rollers to the same direction. We firstly discuss about the mechanical improvements of the Omni Disk to make it lightweight and low cost. We next discusses about four types of methods to attach permanent magnets to the wall-climbing robot and generates attractive force on the iron wall and select the best type based on the motion experiments about the constructed models. As the result of these considerations, we developed a holonomic and omni-directional wall-climbing robot named Vmax III which consists of three Omni Disks having permanent magnet at their center having the function to change the magnetic attractive force. By using the Vmax III, we studied about the relation among the magnetic attractive force of three Omni Disks, posture of the Vmax III and inclination angle of the iron wall and clarified the optimized distribution of the magnetic attractive force of the Omni Disks in different inclination of the iron wall. (author)

  12. Von Reckling-hausen disease associated to thyroid carcinoma and malignant schwannoma of the chest wall. A case

    International Nuclear Information System (INIS)

    Diaz P, J.; Tantalean, E.; Guzman, R.; Pomatanta P, J.; Grados M, J.; Vilela, C.

    1999-01-01

    The multiple neurofibromatosis is an autosomal dominant hereditary disease associated to malignant schwannoma in about 3% of the cases and very rarely to others cancers. The study provides information on the case of a 32 year-old woman who suffers from this disease and presented two synchronous cancers: a papillary carcinoma of thyroid and a malignant schwannoma of the chest wall. The thyroid tumour was managed with hemithyroidectomy, hormonotherapy and radiotherapy, and the lesion of the thoracic wall was treated with local radical resection application of Marlex mesh and rotation of a musculocutaneous flap of the dorsal muscle. A review of the literature on the clinical aspects of this association and the surgical techniques employed to cover the defect of the chest wall is presented. (authors)

  13. SU-E-P-12: Pinnacle-Based Tool to Evaluate the Effect of Prostate Rotation as Determined by Calypso

    International Nuclear Information System (INIS)

    Narayanan, S; Velasco-Schmitz, R; Claeys, K; Cho, P

    2015-01-01

    Purpose: When the Calypso reports a large prostate rotation and one does not have the means to make corrections, it is helpful to quantify its dosimetric effects. We have devised a simple scheme to achieve this in Pinnacle TPS. If it is determined that the PTV margin is inadequate, an alternate larger-margin plan may be adapted for the day. Methods: A three-step process using the Pinnacle Image fusion module was formulated to analyze the clinical effect of prostate rotation. The process includes (1) translating the image set such that the rotational axis is about the isocenter, (2) performing 3D rotations of the structures of interest, and (3) restoring the coordinates associated with the plan. The rotated structures are imported and overlayed on the original plan for evaluation. The tool was applied to three prostate cancer patients with relatively large rotations (95 fractions total). Prostate rotations are primarily due to variations in bladder and rectal filling, which may also affect the seminal vesicles. It is difficult to estimate the perturbation of seminal vesicles for a given prostate rotation. Therefore, the Calypso-derived rotation matrix was applied only to CTV and PTV (CTV+5mm). Results: The rotations were predominantly in the pitch direction with an absolute value ranging from 0–29 degrees (Median = 10°, Average = 14.5°). For various magnitudes of rotation, the CTV V100 decreased from the original 100% to 99.6%/99%/95% for 10°/15°/29° rotations, respectively. Likewise, the PTV V100 diminished from 95% to 92%/89%/82%. Conclusion: A tool, consisting only of features within a TPS, was used to evaluate the dosimetric effect of prostate rotation. Our study shows that under large uncorrected rotations, the tumor coverage is degraded and may require intervention in the form of plan adaptation. To this end, alternate plans with variable margins can be generated in advance for daily adaption

  14. AC electric field induced dipole-based on-chip 3D cell rotation.

    Science.gov (United States)

    Benhal, Prateek; Chase, J Geoffrey; Gaynor, Paul; Oback, Björn; Wang, Wenhui

    2014-08-07

    The precise rotation of suspended cells is one of the many fundamental manipulations used in a wide range of biotechnological applications such as cell injection and enucleation in nuclear transfer (NT) cloning. Noticeably scarce among the existing rotation techniques is the three-dimensional (3D) rotation of cells on a single chip. Here we present an alternating current (ac) induced electric field-based biochip platform, which has an open-top sub-mm square chamber enclosed by four sidewall electrodes and two bottom electrodes, to achieve rotation about the two axes, thus 3D cell rotation. By applying an ac potential to the four sidewall electrodes, an in-plane (yaw) rotating electric field is generated and in-plane rotation is achieved. Similarly, by applying an ac potential to two opposite sidewall electrodes and the two bottom electrodes, an out-of-plane (pitch) rotating electric field is generated and rolling rotation is achieved. As a prompt proof-of-concept, bottom electrodes were constructed with transparent indium tin oxide (ITO) using the standard lift-off process and the sidewall electrodes were constructed using a low-cost micro-milling process and then assembled to form the chip. Through experiments, we demonstrate rotation of bovine oocytes of ~120 μm diameter about two axes, with the capability of controlling the rotation direction and the rate for each axis through control of the ac potential amplitude, frequency, and phase shift, and cell medium conductivity. The maximum observed rotation rate reached nearly 140° s⁻¹, while a consistent rotation rate reached up to 40° s⁻¹. Rotation rate spectra for zona pellucida-intact and zona pellucida-free oocytes were further compared and found to have no effective difference. This simple, transparent, cheap-to-manufacture, and open-top platform allows additional functional modules to be integrated to become a more powerful cell manipulation system.

  15. Trapped Mode Study For A Rotatable Collimator Design For The LHC Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Liling; Ng, Cho-Kuen; Smith, Jeffery Claiborne; Caspers, Fritz; /SLAC /CERN

    2009-06-23

    A rotatable collimator is proposed for the LHC phase II collimation upgrade. When the beam crosses the collimator, it will excite trapped modes that can contribute to the beam energy loss and power dissipation on the vacuum chamber wall. Transverse trapped modes can also generate transverse kicks on the beam and may thus affect the beam quality. In this paper, the parallel eigensolver code Omega3P is used to search for all the trapped modes below 2 GHz in two collimator designs, one with rectangular and the other with circular vacuum chamber. It is found that the longitudinal trapped modes in the circular vacuum chamber design may cause excessive heating. Adding ferrite tiles on the circular vacuum chamber wall can strongly damp these trapped modes. We will present and discuss the simulation results.

  16. Relativistic Landau levels in the rotating cosmic string spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, M.S. [Universidade Estadual do Ceara, Grupo de Fisica Teorica (GFT), Fortaleza, CE (Brazil); Muniz, C.R. [Universidade Estadual do Ceara, Faculdade de Educacao, Ciencias e Letras de Iguatu, Iguatu, CE (Brazil); Christiansen, H.R. [Instituto Federal de Ciencia, Educacao e Tecnologia, IFCE Departamento de Fisica, Sobral (Brazil); Bezerra, V.B. [Universidade Federal da Paraiba-UFPB, Departamento de Fisica, Caixa Postal 5008, Joao Pessoa, PB (Brazil)

    2016-09-15

    In the spacetime induced by a rotating cosmic string we compute the energy levels of a massive spinless particle coupled covariantly to a homogeneous magnetic field parallel to the string. Afterwards, we consider the addition of a scalar potential with a Coulomb-type and a linear confining term and completely solve the Klein-Gordon equations for each configuration. Finally, assuming rigid-wall boundary conditions, we find the Landau levels when the linear defect is itself magnetized. Remarkably, our analysis reveals that the Landau quantization occurs even in the absence of gauge fields provided the string is endowed with spin. (orig.)

  17. Historic Low Wall Detection via Topographic Parameter Images Derived from Fine-Resolution DEM

    Directory of Open Access Journals (Sweden)

    Hone-Jay Chu

    2017-11-01

    Full Text Available Coral walls protect vegetation gardens from strong winds that sweep across Xiji Island, Taiwan Strait for half the year. Topographic parameters based on light detection and ranging (LiDAR-based high-resolution digital elevation model (DEM provide obvious correspondence with the expected form of landscape features. The information on slope, curvature, and openness can help identify the location of landscape features. This study applied the automatic landscape line detection to extract historic vegetable garden wall lines from a LiDAR-derived DEM. The three rapid processes used in this study included the derivation of topographic parameters, line extraction, and aggregation. The rules were extracted from a decision tree to check the line detection from multiple topographic parameters. Results show that wall line detection with multiple topographic parameter images is an alternative means of obtaining essential historic wall feature information. Multiple topographic parameters are highly related to low wall feature identification. Furthermore, the accuracy of wall feature detection is 74% compared with manual interpretation. Thus, this study provides rapid wall detection systems with multiple topographic parameters for further historic landscape management.

  18. Break the "wall" and become creative: Enacting embodied metaphors in virtual reality.

    Science.gov (United States)

    Wang, Xinyue; Lu, Kelong; Runco, Mark A; Hao, Ning

    2018-07-01

    This study investigated whether the experience of "breaking the walls", the embodiment of the metaphor "breaking the rules", could enhance creative performance. The virtual reality technology was used to simulate the scenario where participants could "break the walls" while walking in a corridor. Participants were asked to solve the creativity-demanding problems (ie., alternative uses tasks, AUT) in either the "break" condition in which they had to break the walls to move forward in VR, or the "no-break" condition where no barrier walls would appear. Results showed higher AUT originality and AUT fluency in the "break" condition than in the "no-break" condition. Moreover, the effects of "breaking the walls" on AUT originality were fully mediated by cognitive flexibility and persistence. These findings may indicate that enacting metaphors such as "breaking the rules" contribute to creative performance. The enhanced cognitive flexibility and persistence may account for the benefits. Copyright © 2018 Elsevier Inc. All rights reserved.

  19. The zero-wall puncture: a novel angiographic puncture technique with substantial benefits

    International Nuclear Information System (INIS)

    Leswick, D.A.; Szkup, P.; Stoneham, G.W.

    2005-01-01

    Medical education can be busy, exhausting, and stressful, with potential adverse effects on trainees' physical and mental health. Radiology residency is no exception. In addition to increased daily workload and study requirements, Canadian radiology residents are performing a diverse and increasing number of emergent diagnostic examinations after hours. In an attempt to improve resident self-worth and efficiency during angiographic rotations, we investigated the effects of a novel angiographic puncture procedure on various resident lifestyle indexes. Standard techniques for accessing the femoral artery are either the single-wall puncture or double-wall puncture (Seldinger technique). Both of these techniques are widely known and practiced. Following procedure completion, hemostasis must be achieved at the puncture site. This has traditionally required manual compression at the puncture site, which may require 15 to 20 minutes. At our institution the standard policy is that 'whoever makes the puncture, compresses the groin,' also known as 'you broke it, you fix it'. This has prompted our industrious resident complement to develop a novel, previously undescribed, angiographic puncture technique known as the 'zero-wall puncture technique.' Preliminary unpublished results from our institution show that when residents employ the zero-wall puncture technique the attending staff radiologist subsequently both performs the puncture and compresses the groin at the end of the procedure. We investigated the effect of zero-wall puncture on various resident lifestyle indexes. (author)

  20. Generation and Sustainment of Plasma Rotation by ICRF Heating

    Science.gov (United States)

    Perkins, F. W.

    2000-10-01

    When tokamak plasmas are heated by the fundamental minority ion-cyclotron process, they are observed to rotate toroidally, even though this heating process introduces negligable angular momentum. This work proposes and evaluates a physics mechanism which resolves this apparent conflict. The argument has two elements. First, it is assumed that angular momentum transport is governed by a diffusion equation with a v_tor = 0 boundary condition at the plasma surface and a torque-density source. When the source consists of separated regions of positive and negative torque density, a finite central rotation velocity results, even though the volume integrated torque density - the angular momentum input - vanishes. Secondly, ions energized by the ICRF process can generate separated regions of positive and negative torque density. Heating increases their banana widths which leads to radial energetic-particle transport that must be balanced by neutralizing radial currents and a j_rB_pR torque density in the bulk plasma. Additional, comparable torque density results from collisional transfer of mechanical angular momentum from energetic particles to the bulk plasma and particle loss through banana particles impacting the wall. Monte-Carlo calculations utilizing the ORBIT code evaluate all sources of torque density and rigorously assure that no net angular momentum is introduced. Two models of ICRF heating, diffusive and instantaneous, give similar results. When the resonance location is on the LFS, the calculated rotation has the magnitude, profile, and co-current sense of Alcator C-Mod observations. For HFS resonance locations, the model predicts counter-current rotation. Scans of rotational profiles vs. resonance location, initial energy, particle loss, pitch, and qm will be presented as will the location of the velocity shear layer its scaling to a reactor.

  1. The role of short-rotation woody crops in sustainable development

    International Nuclear Information System (INIS)

    Shepard, J.P.; Tolbert, V.R.

    1996-01-01

    One answer to increase wood production is by increasing management intensity on existing timberland, especially in plantation forests. Another is to convert land currently in agriculture to timberland. Short-rotation woody crops can be used in both cases. But, what are the environmental consequences? Short-rotation woody crops can provide a net improvement in environmental quality at both local and global scales. Conversion of agricultural land to short-rotation woody crops can provide the most environmental quality enhancement by reducing erosion, improving soil quality, decreasing runoff, improving groundwater quality, and providing better wildlife habitat. Forest products companies can use increased production from intensively managed short-rotation woody crop systems to offset decreased yield from the portion of their timberland that is managed less intensively, e.g. streamside management zones and other ecologically sensitive or unique areas. At the global scale, use of short-rotation woody crops for bioenergy is part of the solution to reduce greenhouse gases produced by burning fossil fuels. Incorporating short-rotation woody crops into the agricultural landscape also increases storage of carbon in the soil, thus reducing atmospheric concentrations. In addition, use of wood instead of alternatives such as steel, concrete, and plastics generally consumes less energy and produces less greenhouse gases. Cooperative research can be used to achieve energy, fiber, and environmental goals. This paper will highlight several examples of ongoing cooperative research projects that seek to enhance the environmental aspects of short-rotation woody crop systems. Government, industry, and academia are conducting research to study soil quality, use of mill residuals, nutrients in runoff and groundwater, and wildlife use of short-rotation woody crop systems in order to assure the role of short-rotation crops as a sustainable way of meeting society's needs

  2. Three-dimensional motion of the uncovertebral joint during head rotation.

    Science.gov (United States)

    Nagamoto, Yukitaka; Ishii, Takahiro; Iwasaki, Motoki; Sakaura, Hironobu; Moritomo, Hisao; Fujimori, Takahito; Kashii, Masafumi; Murase, Tsuyoshi; Yoshikawa, Hideki; Sugamoto, Kazuomi

    2012-10-01

    The uncovertebral joints are peculiar but clinically important anatomical structures of the cervical vertebrae. In the aged or degenerative cervical spine, osteophytes arising from an uncovertebral joint can cause cervical radiculopathy, often necessitating decompression surgery. Although these joints are believed to bear some relationship to head rotation, how the uncovertebral joints work during head rotation remains unclear. The purpose of this study is to elucidate 3D motion of the uncovertebral joints during head rotation. Study participants were 10 healthy volunteers who underwent 3D MRI of the cervical spine in 11 positions during head rotation: neutral (0°) and 15° increments to maximal head rotation on each side (left and right). Relative motions of the cervical spine were calculated by automatically superimposing a segmented 3D MR image of the vertebra in the neutral position over images of each position using the volume registration method. The 3D intervertebral motions of all 10 volunteers were standardized, and the 3D motion of uncovertebral joints was visualized on animations using data for the standardized motion. Inferred contact areas of uncovertebral joints were also calculated using a proximity mapping technique. The 3D animation of uncovertebral joints during head rotation showed that the joints alternate between contact and separation. Inferred contact areas of uncovertebral joints were situated directly lateral at the middle cervical spine and dorsolateral at the lower cervical spine. With increasing angle of rotation, inferred contact areas increased in the middle cervical spine, whereas areas in the lower cervical spine slightly decreased. In this study, the 3D motions of uncovertebral joints during head rotation were depicted precisely for the first time.

  3. Feedback control of resistive wall modes in toroidal devices

    International Nuclear Information System (INIS)

    Liu Yueqiang; Bondeson, A.; Gregoratto, D.; Fransson, C.M.; Gribov, Y.; Paccagnella, R.

    2003-01-01

    Feedback of nonaxisymmetric resistive wall modes (RWM) is studied analytically for cylindrical plasmas and computationally for high beta tokamaks. Internal poloidal sensors give superior performance to radial sensors, and this is explained by the distribution of poles and residues for the transfer functions. A single poloidal array of feedback coils allows robust control with respect to variations in plasma pressure, current and rotation velocity. The control analysis is applied to advanced scenarios for ITER. Studies are also shown of configurations with multiple poloidal coils and of feedback systems for nonresonant MHD instabilities in reversed field pinches. (author)

  4. Mitigating Groundwater Depletion in North China Plain with Cropping System that Alternate Deep and Shallow Rooted Crops

    Directory of Open Access Journals (Sweden)

    Xiao-Lin Yang

    2017-06-01

    Full Text Available In the North China Plain, groundwater tables have been dropping at unsustainable rates of 1 m per year due to irrigation of a double cropping system of winter wheat and summer maize. To reverse the trend, we examined whether alternative crop rotations could save water. Moisture contents were measured weekly at 20 cm intervals in the top 180 cm of soil as part of a 12-year field experiment with four crop rotations: sweet potato→ cotton→ sweet potato→ winter wheat-summer maize (SpCSpWS, 4-year cycle; peanuts → winter wheat-summer maize (PWS, 2-year cycle; ryegrass–cotton→ peanuts→ winter wheat-summer maize (RCPWS, 3-year cycle; and winter wheat-summer maize (WS, each year. We found that, compared to WS, the SpCSpWS annual evapotranspiration was 28% lower, PWS was 19% lower and RCPWS was 14% lower. The yield per unit of water evaporated improved for wheat within any alternative rotation compared to WS, increasing up to 19%. Average soil moisture contents at the sowing date of wheat in the SpCSpWS, PWS, and RCPWS rotations were 7, 4, and 10% higher than WS, respectively. The advantage of alternative rotations was that a deep rooted crop of winter wheat reaching down to 180 cm followed shallow rooted crops (sweet potato and peanut drawing soil moisture from 0 to 120 cm. They benefited from the sequencing and vertical complementarity of soil moisture extraction. Thus, replacing the traditional crop rotation with cropping system that involves rotating with annual shallow rooted crops is promising for reducing groundwater depletion in the North China Plain.

  5. A new method for fabrication of thin plates and thin-walled cylinder made of fiber reinforced metal (FRM) and its application for the rotating drum of the nuclear fuel centrifugal separator

    International Nuclear Information System (INIS)

    Okamura, Tatsuya

    1978-01-01

    The composite materials using resins as the base materials show the defect that the characteristics deteriorate rapidly at elevated temperature. Therefore the FRMs using relatively ductile metals as the base materials combined with reinforcing fibers have been considered. The result of study on the combination of base materials and fibers and the manufacturing method is rarely reported in Japan. In FRMs, direct contact of fibers mutually must be avoided, especially making nodes lowers the strength extremely. The fibers must be long monofilaments of 0.1 to 0.2 mm diameter. High precision wire winding machines are required for making uniform FRMs. For the diffusion joining of preformed materials, in which fibers are put in order on metallic foils, pressure and heat are applied. The author succeeded to develop the technique for making thin-walled cylinders of FRMs, including the method of winding brittle filaments and the method of pressurizing and heating based on the difference of thermal expansion of dies. The mechanical properties of thin plates and thin-walled cylinders made of monofilaments of B, SiC and SUS and aluminum alloy foils were obtained, and rotation test of the cylinders was carried out. It was clarified that the FRMs of B-Al and SiC-Al groups are very excellent materials, and most suitable for the rotary drums of super-high speed centrifuges. (Kako, I.)

  6. Nanoparticles in dilute solution : A numerical study of rotational diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Evensen, Tom Richard

    2008-06-15

    This thesis is dedicated to Brownian dynamics simulations of rotational diffusion. A rotation dynamics engine has been implemented and tested. This engine will in the future be integrated as a part of a complete Brownian dynamics simulation tool. The special case, when translational motion can be ignored, has thoroughly been studied. Two choices of generalized coordinates describing angular orientation of the particles are used. The Euler angles, which constitute the classical choice, and the Cartesian components of the rotation vector, which was recently introduced as an alternative, are being compared with regards to computational efficiency. Results from both equilibrium and non-equilibrium simulations are presented. The consistency of two new algorithms is demonstrated on systems of free rigid particles with arbitrary surface topographies. The algorithms make use of only the principal values of the rotational mobility tensor, assuming the corresponding principal axes coincide with the body-fixed coordinate system. These three scalars contain all information about the particle surface topography relevant for rotational diffusion. The calculation of the mobility tensor can be performed in a pre-calculation step, which makes the algorithm itself highly efficient. Both choices of generalized coordinates correctly reproduce theoretical predictions, but we have found that the algorithm using the Cartesian components of the rotation vector as generalized coordinates outperform its counterpart using the Euler angles by up to a factor 1000 in extreme cases. The reason for this improvement is that the algorithm using the Cartesian components of the rotation vector is free of singularities. (Author). refs. figs

  7. Design of rotating mirror for ultra-high speed camera based on dynamic characteristic

    International Nuclear Information System (INIS)

    Li Chunbo; Chai Jinlong; Liang Yexing; Liu Chunping; Wang Hongzhi; Yu Chunhui; Li Jingzhen; Huang Hongbin

    2011-01-01

    A systematic design method has been proposed for studying the dynamic design of rotating mirror for ultra-high speed camera. With the finite element software, the numerical analyses of static, modal, harmonic responses and natural frequency sensitivity for the preliminary-designed rotating mirror were done based on the static and dynamic theories. Some experiments were done to verify the results. The physical dimensions of the rotating mirror were modified repeatedly according to the results for designing a new rotating mirror. Then simulation and experiments of fatigue life for the new rotating mirror under alternating force were done. The results show that the maximum static stress is less than the yield stress of the rotating mirror material, which proves the new rotating mirror will not be subjected to static strength failure. However, the results of modal and harmonic response analyses indicate that the dynamic characteristic of the new rotating mirror can not meet the design requirement for the first critical speed is less than the service speed. In all the physical dimensions of the rotating mirror, the circum radius of mirror body and natural frequency are negatively correlated and the degree of correlation is maximal. The first-order natural frequency in- creases from 459.4 Hz to 713.6 Hz, the rate of change is 55.3%, the first critical speed is up to 42 816 r/min, avoiding resonance successfully, and the fatigue strength of the new rotating mirror can meet the design requirement. (authors)

  8. A Vision-Based Dynamic Rotational Angle Measurement System for Large Civil Structures

    Science.gov (United States)

    Lee, Jong-Jae; Ho, Hoai-Nam; Lee, Jong-Han

    2012-01-01

    In this paper, we propose a vision-based rotational angle measurement system for large-scale civil structures. Despite the fact that during the last decade several rotation angle measurement systems were introduced, they however often required complex and expensive equipment. Therefore, alternative effective solutions with high resolution are in great demand. The proposed system consists of commercial PCs, commercial camcorders, low-cost frame grabbers, and a wireless LAN router. The calculation of rotation angle is obtained by using image processing techniques with pre-measured calibration parameters. Several laboratory tests were conducted to verify the performance of the proposed system. Compared with the commercial rotation angle measurement, the results of the system showed very good agreement with an error of less than 1.0% in all test cases. Furthermore, several tests were conducted on the five-story modal testing tower with a hybrid mass damper to experimentally verify the feasibility of the proposed system. PMID:22969348

  9. Molecular vibration-rotation spectra starting from the Fues potential

    International Nuclear Information System (INIS)

    Ley Koo, E.

    1976-01-01

    The solution of Schroedinger's equation for the Fues potential is analyzed and compared with the corresponding problems for the Coulomb, harmonic oscillator and molecular potentials. These comparisons allow us to emphasize certain pedagogical, conceptual and computational advantages of the Fues potential which make it a favorable alternative as the starting point in the analysis of molecular vibration-rotation and in the determination of potential energy curves. (author)

  10. Alternative irradiation schemes for NIF and LMJ hohlraums

    Science.gov (United States)

    Bourgade, Jean-Luc; Bowen, Christopher; Gauthier, Pascal; Landen, Otto

    2018-02-01

    We explore two alternative irradiation schemes for the large (‘outer’) and small (‘inner’) angle beams that currently illuminate National Ignition Facility (NIF) and Laser Mégajoule cavities. In the first, while the outer laser beams enter through the usual end laser entrance holes (LEH), the inner beams enter through slots along the cavity axis wall, illuminating the back wall of the cavity. This avoids the current interaction of the inner laser beams with the gold wall bubbles generated by the outer beams, which leads to large time-dependent changes in drive symmetry. Another scheme potentially useful for NIF uses only the outer beams. The radiative losses through the slots or from the use of outer beams only are compensated by using a smaller cavity and LEH.

  11. Rotating field current drive in spherical plasmas

    International Nuclear Information System (INIS)

    Brotherton-Ratcliffe, D.; Storer, R.G.

    1988-01-01

    The technique of driving a steady Hall current in plasmas using a rotating magnetic field is studied both numerically and analytically in the approximation of negligible ion flow. A spherical plasma bounded by an insulating wall and immersed in a uniform magnetic field which has both a rotating component (for current drive) and a constant ''vertical'' component (for MHD equilibrium) is considered. The problem is formulated in terms of an expansion of field quantities in vector spherical harmonics. The numerical code SPHERE solves the resulting pseudo-harmonic equations by a multiple shooting technique. The results presented, in addition to being relevant to non-inductive current drive generally, have a direct relevance to the rotamak experiments. For the case of no applied vertical field the steady state toroidal current driven by the rotating field per unit volume of plasma is several times less than in the long cylinder limit for a plasma of the same density, resistivity and radius. The application of a vertical field, which for certain parameter regimes gives rise to a compact torus configuration, improves the current drive dramatically and in many cases gives ''better'' current drive than the long cylinder limit. This result is also predicted by a second order perturbation analysis of the pseudo-harmonic equations. A steady state toroidal field is observed which appears consistent with experimental observations in rotamaks regarding magnitude and spatial dependence. This is an advance over previous analytical theory which predicted an oppositely directed toroidal field of undefined magnitude. (author)

  12. Influence of plasma rotation on tearing mode stability on the ASDEX upgrade tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Fietz, Sina Marie Ariane

    2013-12-16

    Neoclassical tearing modes (NTM) are one of the most serious performance limiting instabilities in next-step fusion devices like ITER. NTMs are destabilised as a consequence of a seed perturbation (trigger) and are driven by a loss of helical bootstrap current inside the island. The appearance of these instabilities is accompanied with a loss of confined plasma energy. Additionally, these modes can stop the plasma rotation, lock to the vessel wall, flush out all plasma energy and terminate a discharge via a disruption. In ITER the confinement reduction will limit the achievable fusion power, whereas a disruption is likely to damage the vessel wall. In order to mitigate and control NTMs in ITER, extrapolations based on the present understanding and observations must be made. One key issue is the rotation dependence of NTMs, especially at the NTM onset. ITER will be operated at low plasma rotation, which is different from most present day experiments. No theory is currently available to describe this dependence. Experiments are therefore required to provide a basis for the theory to describe the physics. Additionally from the experiments scalings can be developed and extrapolated in order to predict the NTM behaviour in the parameter range relevant for ITER. Another important issue is the influence of externally applied magnetic perturbation (MP) fields on the NTM stability and frequency. These fields will be used in ITER primarily for the mitigation of edge instabilities. As a side effect they can slow down an NTM and the plasma rotation, which supports the appearance of locked modes. Additionally, they can also influence the stability of an NTM. This interaction has to be predicted for ITER, based on models validated at present day devices. In this work the influence of plasma rotation on the NTM onset at the ASDEX Upgrade tokamak (AUG) is investigated. An onset database has been created in which the different trigger mechanisms have been identified. Based on this

  13. Influence of plasma rotation on tearing mode stability on the ASDEX upgrade tokamak

    International Nuclear Information System (INIS)

    Fietz, Sina Marie Ariane

    2013-01-01

    Neoclassical tearing modes (NTM) are one of the most serious performance limiting instabilities in next-step fusion devices like ITER. NTMs are destabilised as a consequence of a seed perturbation (trigger) and are driven by a loss of helical bootstrap current inside the island. The appearance of these instabilities is accompanied with a loss of confined plasma energy. Additionally, these modes can stop the plasma rotation, lock to the vessel wall, flush out all plasma energy and terminate a discharge via a disruption. In ITER the confinement reduction will limit the achievable fusion power, whereas a disruption is likely to damage the vessel wall. In order to mitigate and control NTMs in ITER, extrapolations based on the present understanding and observations must be made. One key issue is the rotation dependence of NTMs, especially at the NTM onset. ITER will be operated at low plasma rotation, which is different from most present day experiments. No theory is currently available to describe this dependence. Experiments are therefore required to provide a basis for the theory to describe the physics. Additionally from the experiments scalings can be developed and extrapolated in order to predict the NTM behaviour in the parameter range relevant for ITER. Another important issue is the influence of externally applied magnetic perturbation (MP) fields on the NTM stability and frequency. These fields will be used in ITER primarily for the mitigation of edge instabilities. As a side effect they can slow down an NTM and the plasma rotation, which supports the appearance of locked modes. Additionally, they can also influence the stability of an NTM. This interaction has to be predicted for ITER, based on models validated at present day devices. In this work the influence of plasma rotation on the NTM onset at the ASDEX Upgrade tokamak (AUG) is investigated. An onset database has been created in which the different trigger mechanisms have been identified. Based on this

  14. An out-of-plane rotational energy harvesting system for low frequency environments

    International Nuclear Information System (INIS)

    Febbo, M.; Machado, S.P.; Gatti, C.D.; Ramirez, J.M.

    2017-01-01

    Highlights: • An alternative to cantilever beam-type systems for energy harvesting is proposed. • The device generates energy in a low frequency rotational environment. • It comprises two beams, a spring and two heavy masses joined by the spring. • By varying the flexibility of one beam, the device increments output DC power. • The generated DC power suffices to feed low power wireless transmitters. - Abstract: We present a novel design of a rotational power scavenging system as an alternative to cantilever beams attached to a hub. The device is meant to provide energy to wireless autonomous monitoring systems in low frequency environments such as wind turbines of 30 kW with rotational speeds of between 50 and 150 rpm. These characteristics define the bandwidth of the rotational energy harvesting system (REH) and its physical dimensions. A versatile geometric configuration with two elastic beams and two heavy masses joined by a spring is proposed. A piezoelectric sheet is mounted on the primary beam while the REH is placed on a rotating hub with the gravitational force acting as a periodic source. This kind of double-beam system offers the possibility to modify the vibration characteristics of the harvester for achieving high power density. An analytical framework using the Lagrangian formulation is derived to describe the motion of the system and the voltage output as a function of rotation speed. Several sets of experiments were performed to characterize the system and to validate the assumed hypothesis. In the experimental setup, a wireless data acquisition system based on Arduino technology was implemented to avoid slip-ring mechanisms. The results show very good agreement between the theoretical and experimental tests. Moreover, the output power of a simple harvesting circuit, which serves as an energy storage device, yields values ranging 26–105 μW over the whole frequency range. This allows us to use the proposed device for the designed purpose

  15. On the relative rotational motion between rigid fibers and fluid in turbulent channel flow

    Energy Technology Data Exchange (ETDEWEB)

    Marchioli, C. [Department of Electrical, Management and Mechanical Engineering, University of Udine, 33100 Udine (Italy); Zhao, L., E-mail: lihao.zhao@ntnu.no [Department of Energy and Process Engineering, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Andersson, H. I. [Department of Electrical, Management and Mechanical Engineering, University of Udine, 33100 Udine (Italy); Department of Energy and Process Engineering, Norwegian University of Science and Technology, 7491 Trondheim (Norway)

    2016-01-15

    In this study, the rotation of small rigid fibers relative to the surrounding fluid in wall-bounded turbulence is examined by means of direct numerical simulations coupled with Lagrangian tracking. Statistics of the relative (fiber-to-fluid) angular velocity, referred to as slip spin in the present study, are evaluated by modelling fibers as prolate spheroidal particles with Stokes number, St, ranging from 1 to 100 and aspect ratio, λ, ranging from 3 to 50. Results are compared one-to-one with those obtained for spherical particles (λ = 1) to highlight effects due to fiber length. The statistical moments of the slip spin show that differences in the rotation rate of fibers and fluid are influenced by inertia, but depend strongly also on fiber length: Departures from the spherical shape, even when small, are associated with an increase of rotational inertia and prevent fibers from passively following the surrounding fluid. An increase of fiber length, in addition, decouples the rotational dynamics of a fiber from its translational dynamics suggesting that the two motions can be modelled independently only for long enough fibers (e.g., for aspect ratios of order ten or higher in the present simulations)

  16. Large Eddy Simulation of turbulence induced secondary flows in stationary and rotating straight square ducts

    Science.gov (United States)

    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.

  17. Reconstruction of 3D flow structures in a cylindrical cavity with a rotating lid using time-resolved stereo PIV

    DEFF Research Database (Denmark)

    Meyer, Knud Erik; Sørensen, Jens Nørkær; Naumov, Igor

    2009-01-01

    variations. The flow in a cylindrical cavity with a rotating lid of a height of three radii and a Reynolds number of about 3500 is used as example. The reconstruction identifies a series of flow structures including axisymmetric vortex breakdown and distinct vortex structures along the cylinder wall....

  18. Design of SC walls and slabs for impulsive loading

    Energy Technology Data Exchange (ETDEWEB)

    Varma, Amit H. [Purdue Univ., West Lafayette, IN (United States)

    2015-11-11

    Reinforced concrete (RC) structures have historically been the preferred choice for blast resistant structures because of their mass and the ductility provided by steel reinforcement. Steel-plate composite (SC) walls are a viable alternative to RC for protecting the infrastructure against explosive threats. SC structures consist of two steel faceplates with a plain concrete core between them. The steel faceplates are anchored to the concrete using stud anchors and connected to each other using tie bars. SC structures provide mass from the concrete infill and ductility from the continuous external steel faceplates. This dissertation presents findings and recommendations from experimental and analytical investigations of the performance of SC walls subjected to far-field blast loads.

  19. Reflections on a flat wall

    International Nuclear Information System (INIS)

    Stevenson, G.R.; Huhtinen, M.

    1995-01-01

    This paper describes an investigation into whether estimates of attenuation in the flat sidewalls of the tunnel for the MC main ring can be based on a simple point-source/line-of-sight model. Having seen the limitations of such a model, an alternative is proposed where the main radiation source is not the initial object struck by the beam but the plane source provided by the first interactions of secondaries from the target in the shield-wall. This is shown to have a closer relation to reality than the point-source/line-of-sight model. (author)

  20. Bladder wall thickness mapping for magnetic resonance cystography

    International Nuclear Information System (INIS)

    Zhao Yang; Liang Zhengrong; Zhu Hongbin; Han Hao; Yan Zengmin; Duan Chaijie; Lu Hongbing; Gu Xianfeng

    2013-01-01

    Clinical studies have shown evidence that the bladder wall thickness is an effective biomarker for bladder abnormalities. Clinical optical cystoscopy, the current gold standard, cannot show the wall thickness. The use of ultrasound by experts may generate some local thickness information, but the information is limited in field-of-view and is user dependent. Recent advances in magnetic resonance (MR) imaging technologies lead MR-based virtual cystoscopy or MR cystography toward a potential alternative to map the wall thickness for the entire bladder. From a high-resolution structural MR volumetric image of the abdomen, a reasonable segmentation of the inner and outer borders of the bladder wall can be achievable. Starting from here, this paper reviews the limitation of a previous distance field-based approach of measuring the thickness between the two borders and then provides a solution to overcome the limitation by an electric field-based strategy. In addition, this paper further investigates a surface-fitting strategy to minimize the discretization errors on the voxel-like borders and facilitate the thickness mapping on the three-dimensional patient-specific bladder model. The presented thickness calculation and mapping were tested on both phantom and human subject datasets. The results are preliminary but very promising with a noticeable improvement over the previous distance field-based approach. (paper)

  1. Development of real time monitoring for ITER first wall erosion

    International Nuclear Information System (INIS)

    Berryman, Ian.; Pallaras, Luke; Thomson, Laura; Wang, Michael; Riley, Daniel P.

    2009-01-01

    Full text: This project aims to contribute to the current research on the first wall erosion diagnostic for the ITER fusion reactor. The plasma-facing first wall tiles of the ITER tokamak reactor are exposed to an expected neutron flux of O. 7 8 M W/m2 and a thermal load of O. 5M W/m 2 during operation. Instabilities in the magnetically confined plasma, such as edge-Iocalised modes, cause the plasma to come into direct contact with the first wall. The resulting thermal loads can vaporise and ablate the tile material. Moreover, a flux of high-energy neutrons produced during the fusion process results in a range of radiation effects. Therefore, a diagnostic is necessary to monitor the extent and rate of damage caused to the first wall. We have considered and critically assessed the viability of six alternative diagnostic methods, encompassing both established and novel concepts. From these, a design featuring embedded conducting elements was selected as the strongest candidate, as by monitoring electrical signals it has the potential to detect both bulk erosion and radiation damage.

  2. Lower abdominal wall reconstructions with pedicled rectus femoris flaps

    International Nuclear Information System (INIS)

    Arashiro, Ken; Nishizeki, Osamu; Ishida, Kunihiro

    2003-01-01

    During the past 10 years, seven pedicled rectus femoris muscle or musculocutaneous flaps were used to repair lower abdominal defects; three recalcitrant incisional hernias with previous radiotherapy, two long-standing wound infections after synthetic mesh reconstruction, one posttraumatic wall defect and one metastatic tumor. There were two flap complications, one skin paddle necrosis and one wound infection. There was no significant disability of the donor limb encountered. During the two-year and seven month average follow-up, there was no recurrence of the problems except for one minor fascial dehiscence in the patient with metastatic abdominal wall tumor. Easy approach, rapid harvest, relatively large and reliable overlying fascia lata, a single dominant neurovascular pedicle, easy primary closure of the donor site, and minimal donor site morbidity all make the rectus femoris flap a good alternative flap for lower abdominal wall reconstruction. It is especially useful in a condition where synthetic mesh would be unsuitable for defects with infection or recurrent incisional hernia after radiotherapy. (author)

  3. Sasol Coal`s `better brick` for colliery ventilation walls

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-12-01

    Sasol coal has developed a better brick for construction of ventilation walls underground. It has proven to be a speedy and cost-saving alternative to the standard concrete block used for the purpose. The brick has an interlocking design ensuring that it is laid correctly. Unlike the conventional concrete block, the ventilation walls built for the new brick do not have to be plastered to achieve airtightness. The skills required to build such walls are minimal as the design of the brick makes it virtually impossible to lay it badly or unevenly - further facilitated by the absence of mortar. While introducing the new method Sasol Coal took the opportunity to introduce a purpose-made trailer for transporting the bricks, with the trailer doubling as a building platform on site. This has further contributed to the efficiency and speed of the operation. It has also reduced to a minimum the number of times the bricks are handled, thus cutting down on breakages. 1 fig.

  4. Angular momentum transfer in primordial discs and the rotation of the first stars

    Science.gov (United States)

    Hirano, Shingo; Bromm, Volker

    2018-05-01

    We investigate the rotation velocity of the first stars by modelling the angular momentum transfer in the primordial accretion disc. Assessing the impact of magnetic braking, we consider the transition in angular momentum transport mode at the Alfvén radius, from the dynamically dominated free-fall accretion to the magnetically dominated solid-body one. The accreting protostar at the centre of the primordial star-forming cloud rotates with close to breakup speed in the case without magnetic fields. Considering a physically motivated model for small-scale turbulent dynamo amplification, we find that stellar rotation speed quickly declines if a large fraction of the initial turbulent energy is converted to magnetic energy (≳ 0.14). Alternatively, if the dynamo process were inefficient, for amplification due to flux freezing, stars would become slow rotators if the pre-galactic magnetic field strength is above a critical value, ≃10-8.2 G, evaluated at a scale of nH = 1 cm-3, which is significantly higher than plausible cosmological seed values (˜10-15 G). Because of the rapid decline of the stellar rotational speed over a narrow range in model parameters, the first stars encounter a bimodal fate: rapid rotation at almost the breakup level, or the near absence of any rotation.

  5. Stokes drag on a disc with a Navier slip condition near a plane wall

    International Nuclear Information System (INIS)

    Sherwood, J D

    2013-01-01

    The Stokes drag and couple acting on a disc moving through incompressible Newtonian fluid are investigated for the case when the fluid obeys a Navier slip condition, with slip length b, on the surface of the disc. The fluid is bounded by an infinite plane wall on which there is no slip. The disc, of zero thickness and radius a, is parallel to the wall and distance h from it. Analyses are presented for the limits h ≫ a and h ≪ a; results for intermediate values of the separation h are obtained numerically by means of Tranter's method. The resistance coefficients for translation normal to the disc surface, and for rotation about a diameter, are unaffected by slip when the disc lies in unbounded fluid, but all resistance coefficients depend upon the slip length b when the disc is close to the wall. Their dependence on h becomes weak when b ≫ a. (paper)

  6. Analysis of ultrasonically rotating droplet using moving particle semi-implicit and distributed point source methods

    Science.gov (United States)

    Wada, Yuji; Yuge, Kohei; Tanaka, Hiroki; Nakamura, Kentaro

    2016-07-01

    Numerical analysis of the rotation of an ultrasonically levitated droplet with a free surface boundary is discussed. The ultrasonically levitated droplet is often reported to rotate owing to the surface tangential component of acoustic radiation force. To observe the torque from an acoustic wave and clarify the mechanism underlying the phenomena, it is effective to take advantage of numerical simulation using the distributed point source method (DPSM) and moving particle semi-implicit (MPS) method, both of which do not require a calculation grid or mesh. In this paper, the numerical treatment of the viscoacoustic torque, which emerges from the viscous boundary layer and governs the acoustical droplet rotation, is discussed. The Reynolds stress traction force is calculated from the DPSM result using the idea of effective normal particle velocity through the boundary layer and input to the MPS surface particles. A droplet levitated in an acoustic chamber is simulated using the proposed calculation method. The droplet is vertically supported by a plane standing wave from an ultrasonic driver and subjected to a rotating sound field excited by two acoustic sources on the side wall with different phases. The rotation of the droplet is successfully reproduced numerically and its acceleration is discussed and compared with those in the literature.

  7. Reconstruction with a patient-specific titanium implant after a wide anterior chest wall resection

    Science.gov (United States)

    Turna, Akif; Kavakli, Kuthan; Sapmaz, Ersin; Arslan, Hakan; Caylak, Hasan; Gokce, Hasan Suat; Demirkaya, Ahmet

    2014-01-01

    The reconstruction of full-thickness chest wall defects is a challenging problem for thoracic surgeons, particularly after a wide resection of the chest wall that includes the sternum. The location and the size of the defect play a major role when selecting the method of reconstruction, while acceptable cosmetic and functional results remain the primary goal. Improvements in preoperative imaging techniques and reconstruction materials have an important role when planning and performing a wide chest wall resection with a low morbidity rate. In this report, we describe the reconstruction of a wide anterior chest wall defect with a patient-specific custom-made titanium implant. An infected mammary tumour recurrence in a 62-year old female, located at the anterior chest wall including the sternum, was resected, followed by a large custom-made titanium implant. Latissimus dorsi flap and split-thickness graft were also used for covering the implant successfully. A titanium custom-made chest wall implant could be a viable alternative for patients who had large chest wall tumours. PMID:24227881

  8. Magnetic field and rotation effects on peristaltic transport of a Jeffrey fluid in an asymmetric channel

    International Nuclear Information System (INIS)

    Abd-Alla, A.M.; Abo-Dahab, S.M.

    2015-01-01

    In this paper, the peristaltic flow of a Jeffrey fluid in an asymmetric rotating channel is studied. Mathematical modeling is carried out by utilizing long wavelength and low Reynolds number assumptions. Closed form expressions for the pressure gradient, pressure rise, streamlines, axial velocity and shear stress on the channel walls have been computed numerically. Effects of Hartmann number, the ratio of relaxation to retardation times, time-mean flow, rotation and the phase angle on the pressure gradient, pressure rise, streamline, axial velocity and shear stress are discussed in detail and shown graphically. The results indicate that the effect of the Hartmann number, the ratio of relaxation to retardation times, time-mean flow, rotation and the phase angle are very pronounced in the phenomena. Comparison was made with the results obtained in the asymmetric channel and symmetric channel. - Highlights: • The peristaltic flow of a Jeffrey fluid in an asymmetric rotating channel with magnetic field. • Mathematical modeling for long wavelength and low Reynolds number assumptions. • Closed form expressions for the pressure gradient, pressure rise, stream function, axial velocity and shear stress

  9. Modulated Magnetic Nanowires for Controlling Domain Wall Motion: Toward 3D Magnetic Memories

    KAUST Repository

    Ivanov, Yurii P.; Chuvilin, Andrey; Lopatin, Sergei; Kosel, Jü rgen

    2016-01-01

    Cylindrical magnetic nanowires are attractive materials for next generation data storage devices owing to the theoretically achievable high domain wall velocity and their efficient fabrication in highly dense arrays. In order to obtain control over domain wall motion, reliable and well-defined pinning sites are required. Here, we show that modulated nanowires consisting of alternating nickel and cobalt sections facilitate efficient domain wall pinning at the interfaces of those sections. By combining electron holography with micromagnetic simulations, the pinning effect can be explained by the interaction of the stray fields generated at the interface and the domain wall. Utilizing a modified differential phase contrast imaging, we visualized the pinned domain wall with a high resolution, revealing its three-dimensional vortex structure with the previously predicted Bloch point at its center. These findings suggest the potential of modulated nanowires for the development of high-density, three-dimensional data storage devices. © 2016 American Chemical Society.

  10. The forced sound transmission of finite single leaf walls using a variational technique.

    Science.gov (United States)

    Brunskog, Jonas

    2012-09-01

    The single wall is the simplest element of concern in building acoustics, but there still remain some open questions regarding the sound insulation of this simple case. The two main reasons for this are the effects on the excitation and sound radiation of the wall when it has a finite size, and the fact that the wave field in the wall is consisting of two types of waves, namely forced waves due to the exciting acoustic field, and free bending waves due to reflections in the boundary. The aim of the present paper is to derive simple analytical formulas for the forced part of the airborne sound insulation of a single homogeneous wall of finite size, using a variational technique based on the integral-differential equation of the fluid loaded wall. The so derived formulas are valid in the entire audible frequency range. The results are compared with full numerical calculations, measurements and alternative theory, with reasonable agreement.

  11. Modulated Magnetic Nanowires for Controlling Domain Wall Motion: Toward 3D Magnetic Memories

    KAUST Repository

    Ivanov, Yurii P.

    2016-05-03

    Cylindrical magnetic nanowires are attractive materials for next generation data storage devices owing to the theoretically achievable high domain wall velocity and their efficient fabrication in highly dense arrays. In order to obtain control over domain wall motion, reliable and well-defined pinning sites are required. Here, we show that modulated nanowires consisting of alternating nickel and cobalt sections facilitate efficient domain wall pinning at the interfaces of those sections. By combining electron holography with micromagnetic simulations, the pinning effect can be explained by the interaction of the stray fields generated at the interface and the domain wall. Utilizing a modified differential phase contrast imaging, we visualized the pinned domain wall with a high resolution, revealing its three-dimensional vortex structure with the previously predicted Bloch point at its center. These findings suggest the potential of modulated nanowires for the development of high-density, three-dimensional data storage devices. © 2016 American Chemical Society.

  12. A low frequency rotational energy harvesting system

    International Nuclear Information System (INIS)

    Febbo, M; Machado, S P; Ramirez, J M; Gatti, C D

    2016-01-01

    This paper presents a rotary power scavenging unit comprised of two systems of flexible beams connected by two masses which are joined by means of a spring, considering a PZT (QP16N, Midé Corporation) piezoelectric sheet mounted on one of the beams. The energy harvesting (EH) system is mounted rigidly on a rotating hub. The gravitational force on the masses causes sustained oscillatory motion in the flexible beams as long as there is rotary motion. The intention is to use the EH system in the wireless autonomous monitoring of wind turbines under different wind conditions. Specifically, the development is oriented to monitor the dynamic state of the blades of a wind generator of 30 KW which rotates between 50 and 150 rpm. The paper shows a complete set of experimental results on three devices, modifying the amount of beams in the frame supporting the system. The results show an acceptable sustained voltage generation for the expected range, in the three proposed cases. Therefore, it is possible to use this system for generating energy in a low-frequency rotating environment. As an alternative, the system can be easily adapted to include an array of piezoelectric sheets to each of the beams, to provide more power generation. (paper)

  13. Tests of Bed Agglomeration Tendency Using a Rotating Furnace; Roterugn foer bedoemning av sintringsbenaegenhet

    Energy Technology Data Exchange (ETDEWEB)

    Larfeldt, Jenny; Zintl, Frank [TPS Termiska Processer AB, Nykoeping (Sweden)

    2003-08-01

    Bed sintering is a well known problem in fluidised bed boilers. In order to avoid bed sintering the bed material turn over ratio is high which leads a high consumption of bed material. This work aims at developing and evaluating a method for testing the bed agglomeration tendency of a FB bed material by using a rotating furnace. A rotating furnace has been designed and tests have shown that three temperatures describing the increasing agglomeration tendency can be evaluated; TA when several particles stick to each other and to the crucible wall, TB when half of the material sticks to the wall and TC when almost all the material forms a ball in the crucible. Comparison with bed agglomeration tests has shown that TA is between 80 deg C to 130 deg C lower than the bed agglomeration temperature from fluid bed tests. It is shown that TB is closer to the bed agglomeration temperature and finally that the temperature TC is higher than the bed agglomeration temperature. It is concluded that in the rotating furnace sticking of particles is visualised early, and that this sticking will not cause defluidisation of the bed until more than half of the material in the crucible is sticky. Repeated tests has been performed at a heating rate of 5 deg/minute and a rotating speed of 12 rpm and a furnace inclination of 20 deg was found to give distinct results in the evaluation. The evaluation has shown to be reproducible at lower temperatures. At higher temperatures, around 1,000 deg C, the evaluation was complicated by a poor picture quality which probably can be improved by proper cooling of the camera. It has also been shown that sticking of material in the rotating furnace could be detected at relatively low temperatures of 750 deg C that disappeared at higher temperatures. This is likely to be explained by melting salts that evaporates as temperature increase. At even higher temperatures the sticking reappeared until a ball was formed in the crucible. The latter sticking is

  14. Selection of the Best Wastewater Treatment Alternative for RIPI Based on Analytical Hierarchy Process (AHP and Expert Choice Software

    Directory of Open Access Journals (Sweden)

    faramarz Tarkian

    2014-05-01

    Full Text Available RIPI as one of the largest and most important research centers in Iran is located in zone 22 of Tehran municipality. According to the environmental priorities in the region taking all necessary measures to control pollution sources is necessary. In this paper, Analytical Hierarchy Process (AHP method is used for the selection of the best wastewater treatment method for RIPI. For this purpose four alternatives including SBR, Extended aeration activated sludge, Rotating MBR, Fix MBR were evaluated. These alternatives were weighted by four main criteria: Environment, Economic, Technical, Management and the defined sub-criteria ,then paired compared with respect to any form of wastewater treatment alternatives and ultimately the results was evaluated by Expert Choice software. The evaluation results indicate that Rotating MBR was the most suitable alternative of wastewater treatment method for RIPI. After the Rotating MBR, the Fix MBR, SBR and Extended activated sludge were considered suitable respectively. Degree of inconsistency is equal to 0.07, indicating that the number of paired comparisons is consistent.

  15. Consolidation of HIP bonding technologies for the ITER first wall panels

    International Nuclear Information System (INIS)

    Sherlock, P.; Peacock, A.; Roedig, M.

    2006-01-01

    Over the last decade alternative technologies for the manufacture of the ITER first wall have been progressively developed. Now, as the build of ITER approaches, the manufacturing route is being consolidated around the best solutions found to date. The design of the first wall is based on the concept of blanket modules, each faced by separable first wall panels. For the manufacture of the first wall panels two HIP bonding technologies are proposed by AMEC NNC; the first to bond together the composite copper alloy / stainless steel heat sink base, the second to bond the beryllium tiles to the copper alloy surface of the heat sink base. These technologies have been developed incrementally through the use of experiments, part scale mock-ups and full scale first wall panel prototypes. This paper reviews the development of the HIP bonding technologies identified above and discusses the latest results from components produced by AMEC NNC under the auspices of EFDA. The manufacturing stages, non-destructive examination and heat flux test results from the work are presented for the latest first wall mock-up components. Conclusions are then drawn with regard to the important aspects for the series production of components for ITER. (author)

  16. Molecular Dynamics Simulation of a Multi-Walled Carbon Nanotube Based Gear

    Science.gov (United States)

    Han, Jie; Globus, Al; Srivastava, Deepak; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    We used molecular dynamics to investigate the properties of a multi-walled carbon nanotube based gear. Previous work computationally suggested that molecular gears fashioned from (14,0) single-walled carbon nanotubes operate well at 50-100 gigahertz. The gears were formed from nanotubes with teeth added via a benzyne reaction known to occur with C60. A modified, parallelized version of Brenner's potential was used to model interatomic forces within each molecule. A Leonard-Jones 6-12 potential was used for forces between molecules. The gear in this study was based on the smallest multi-walled nanotube supported by some experimental evidence. Each gear was a (52,0) nanotube surrounding a (37,10) nanotube with approximate 20.4 and 16,8 A radii respectively. These sizes were chosen to be consistent with inter-tube spacing observed by and were slightly larger than graphite inter-layer spacings. The benzyne teeth were attached via 2+4 cycloaddition to exterior of the (52,0) tube. 2+4 bonds were used rather than the 2+2 bonds observed by Hoke since 2+4 bonds are preferred by naphthalene and quantum calculations by Jaffe suggest that 2+4 bonds are preferred on carbon nanotubes of sufficient diameter. One gear was 'powered' by forcing the atoms near the end of the outside buckytube to rotate to simulate a motor. A second gear was allowed to rotate by keeping the atoms near the end of its outside buckytube on a cylinder. The ends of both gears were constrained to stay in an approximately constant position relative to each other, simulating a casing, to insure that the gear teeth meshed. The stiff meshing aromatic gear teeth transferred angular momentum from the powered gear to the driven gear. The simulation was performed in a vacuum and with a software thermostat. Preliminary results suggest that the powered gear had trouble turning the driven gear without slip. The larger radius and greater mass of these gears relative to the (14,0) gears previously studied requires a

  17. Alternatives to shallow land burial

    International Nuclear Information System (INIS)

    Kuck, P.H.; Wacks, M.E.

    1980-01-01

    The paper discusses disposal alternatives that suggest there is a great diversity of man-made and natural spaces that should be considered as alternative sites for LLW disposal. Dry caverns outside of karst regions with integrated subsurface drainage might be given further consideration. The excavation of new space in tectonically and chemically stable rock formations also shows considerable promise. The principal problems in using either existing or new space involve hydrology, rock mechanics, chemical stability of the wall-rock minerals, and socio-political interactions. The chemical, physical and radiological properties of the wastes will also enter into the evaluation. All seven of these aspects will have to be examined in detail before a solution to the problem of minimizing radionuclide transport into the biosphere can be outlined

  18. 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.

  19. Computations for nanofluid flow near a stretchable rotating disk with axial magnetic field and convective conditions

    Science.gov (United States)

    Mushtaq, A.; Mustafa, M.

    In this paper, the classical Von Kármán problem of infinite disk is extended when an electrically conducting nanofluid fills the space above the rotating disk which also stretches uniformly in the radial direction. Buongiorno model is considered in order to incorporate the novel Brownian motion and thermophoresis effects. Heat transport mechanism is modeled through more practically feasible convective conditions while Neumann type condition for nanoparticle concentration is adopted. Modified Von Kármán transformations are utilized to obtain self-similar differential system which is treated through a numerical method. Stretching phenomenon yields an additional parameter c which compares the stretch rate with the swirl rate. The effect of parameter c is to reduce the temperature and nanoparticle concentration profiles. Torque required to main steady rotation of the disk increases for increasing values of c while an improvement in cooling rate is anticipated in case of radial stretching, which is important in engineering processes. Brownian diffusion does not influence the heat flux from the stretching wall. Moreover, the wall heat flux has the maximum value for the situation in which thermoporetic force is absent.

  20. Radiative transfer equation accounting for rotational Raman scattering and its solution by the discrete-ordinates method

    International Nuclear Information System (INIS)

    Rozanov, Vladimir V.; Vountas, Marco

    2014-01-01

    Rotational Raman scattering of solar light in Earth's atmosphere leads to the filling-in of Fraunhofer and telluric lines observed in the reflected spectrum. The phenomenological derivation of the inelastic radiative transfer equation including rotational Raman scattering is presented. The different forms of the approximate radiative transfer equation with first-order rotational Raman scattering terms are obtained employing the Cabannes, Rayleigh, and Cabannes–Rayleigh scattering models. The solution of these equations is considered in the framework of the discrete-ordinates method using rigorous and approximate approaches to derive particular integrals. An alternative forward-adjoint technique is suggested as well. A detailed description of the model including the exact spectral matching and a binning scheme that significantly speeds up the calculations is given. The considered solution techniques are implemented in the radiative transfer software package SCIATRAN and a specified benchmark setup is presented to enable readers to compare with own results transparently. -- Highlights: • We derived the radiative transfer equation accounting for rotational Raman scattering. • Different approximate radiative transfer approaches with first order scattering were used. • Rigorous and approximate approaches are shown to derive particular integrals. • An alternative forward-adjoint technique is suggested as well. • An additional spectral binning scheme which speeds up the calculations is presented

  1. Alternative technology of containment construction for WWER 1000 nuclear power plant

    International Nuclear Information System (INIS)

    Chalus, Z.

    1982-01-01

    A number of alternatives was assessed for the assembly of the steel elements of the cylindrical part of containment. Alternative 1 is based on the common technology of manufacture, transport and assembly of reinforced concrete blocks of ca. 3x12 m in size, used for building leak-proof walls of WWER 440 nuclear power plants. Alternative 2 is based on reinforced concrete blocks using 12x12 m blocks assembled from individual elements on the building. site. Alternative 3 is a specific variant of the previous alternative. Alternative 4 envisages the assembly of a prefabricated support structure made of steel. Alternative 5 is based on the gradual assembly of partial elements mounted onto a support structure. Alternative 6 only differs from 5 in the method of assembly and manufacture of the support structure. All alternatives are shown in diagrams. (J.B.)

  2. Resistive wall instabilities and tearing mode dynamics in the EXTRAP T2R thin shell reversed-field pinch

    Science.gov (United States)

    Malmberg, J.-A.; Brunsell, P. R.

    2002-01-01

    Observations of resistive wall instabilities and tearing mode dynamics in the EXTRAP T2R thin shell (τw=6 ms) reversed field pinch are described. A nonresonant mode (m=1,n=-10) with the same handedness as the internal field grows nearly exponentially with an average growth time of about 2.6 ms (less than 1/2 of the shell time) consistent with linear stability theory. The externally nonresonant unstable modes (m=1,n>0), predicted by linear stability theory, are observed to have only low amplitudes (in the normal low-Θ operation mode of the device). The radial field of the dominant internally resonant tearing modes (m=1,n=-15 to n=-12) remain low due to spontaneous fast mode rotation, corresponding to angular phase velocities up to 280 krad/s. Phase aligned mode structures are observed to rotate toroidally with an average angular velocity of 40 krad/s, in the opposite direction of the plasma current. Toward the end of the discharge, the radial field of the internally resonant modes grows as the modes slow down and become wall-locked, in agreement with nonlinear computations. Fast rotation of the internally resonant modes has been observed only recently and is attributed to a change of the front-end system (vacuum vessel, shell, and TF coil) of the device.

  3. Lipid-linked cell wall precursors regulate membrane association of bacterial actin MreB

    OpenAIRE

    Schirner, Kathrin; Eun, Ye-Jin; Dion, Mike; Luo, Yun; Helmann, John D.; Garner, Ethan C.; Walker, Suzanne

    2014-01-01

    Summary The bacterial actin homolog MreB, which is critical for rod shape determination, forms filaments that rotate around the cell width on the inner surface of the cytoplasmic membrane. What determines filament association with the membranes or with other cell wall elongation proteins is not known. Using specific chemical and genetic perturbations while following MreB filament motion, we find that MreB membrane association is an actively regulated process that depends on the presence of li...

  4. Model Solutions for Performance-Based Seismic Analysis of an Anchored Sheet Pile Quay Wall

    OpenAIRE

    C. J. W. Habets; D. J. Peters; J. G. de Gijt; A. V. Metrikine; S. N. Jonkman

    2016-01-01

    Conventional seismic designs of quay walls in ports are mostly based on pseudo-static analysis. A more advanced alternative is the Performance-Based Design (PBD) method, which evaluates permanent deformations and amounts of (repairable) damage under seismic loading. The aim of this study is to investigate the suitability of this method for anchored sheet pile quay walls that were not purposely designed for seismic loads. A research methodology is developed in which pseudo-static, permanent-di...

  5. Development of a novel sports medicine rotation for emergency medicine residents.

    Science.gov (United States)

    Waterbrook, Anna L; Pritchard, T Gail; Lane, Allison D; Stoneking, Lisa R; Koch, Bryna; McAtee, Robert; Grall, Kristi H; Min, Alice A; Prior, Jessica; Farrell, Isaac; McNulty, Holly G; Stolz, Uwe

    2016-01-01

    experience when compared to the traditional orthopedics rotation. All SC residents successfully completed their sports medicine rotation, had completed postrotation evaluations by attending physicians, and had no duty hour violations while on sports medicine. In our experience, a sports medicine rotation is an effective alternative to the traditional orthopedics rotation for EM residents.

  6. Flow characteristics and scaling past highly porous wall-mounted fences

    Science.gov (United States)

    Rodríguez-López, Eduardo; Bruce, Paul J. K.; Buxton, Oliver R. H.

    2017-07-01

    An extensive characterization of the flow past wall-mounted highly porous fences based on single- and multi-scale geometries has been performed using hot-wire anemometry in a low-speed wind tunnel. Whilst drag properties (estimated from the time-averaged momentum equation) seem to be mostly dependent on the grids' blockage ratio; wakes of different size and orientation bars seem to generate distinct behaviours regarding turbulence properties. Far from the near-grid region, the flow is dominated by the presence of two well-differentiated layers: one close to the wall dominated by the near-wall behaviour and another one corresponding to the grid's wake and shear layer, originating from between this and the freestream. It is proposed that the effective thickness of the wall layer can be inferred from the wall-normal profile of root-mean-square streamwise velocity or, alternatively, from the wall-normal profile of streamwise velocity correlation. Using these definitions of wall-layer thickness enables us to collapse different trends of the turbulence behaviour inside this layer. In particular, the root-mean-square level of the wall shear stress fluctuations, longitudinal integral length scale, and spanwise turbulent structure is shown to display a satisfactory scaling with this thickness rather than with the whole thickness of the grid's wake. Moreover, it is shown that certain grids destroy the spanwise arrangement of large turbulence structures in the logarithmic region, which are then re-formed after a particular streamwise extent. It is finally shown that for fences subject to a boundary layer of thickness comparable to their height, the effective thickness of the wall layer scales with the incoming boundary layer thickness. Analogously, it is hypothesized that the growth rate of the internal layer is also partly dependent on the incoming boundary layer thickness.

  7. Shielding synchrotron light sources: Advantages of circular shield walls tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, S.L. [Design and Accelerator Operations Consulting, 568 Wintergreen Ct Ridge, NY 11961 (United States); Ghosh, V.J.; Breitfeller, M. [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2016-08-11

    Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produce significantly higher neutron component dose to the experimental floor than lower energy injection and ramped operations. High energy neutrons produced in the forward direction from thin target beam losses are a major component of the dose rate outside the shield walls of the tunnel. The convention has been to provide thicker 90° ratchet walls to reduce this dose to the beam line users. We present an alternate circular shield wall design, which naturally and cost effectively increases the path length for this forward radiation in the shield wall and thereby substantially decreasing the dose rate for these beam losses. This shield wall design will greatly reduce the dose rate to the users working near the front end optical components but will challenge the beam line designers to effectively utilize the longer length of beam line penetration in the shield wall. Additional advantages of the circular shield wall tunnel are that it's simpler to construct, allows greater access to the insertion devices and the upstream in tunnel beam line components, as well as reducing the volume of concrete and therefore the cost of the shield wall.

  8. Prediction method of seismic residual deformation of caisson quay wall in liquefied foundation

    Science.gov (United States)

    Wang, Li-Yan; Liu, Han-Long; Jiang, Peng-Ming; Chen, Xiang-Xiang

    2011-03-01

    The multi-spring shear mechanism plastic model in this paper is defined in strain space to simulate pore pressure generation and development in sands under cyclic loading and undrained conditions, and the rotation of principal stresses can also be simulated by the model with cyclic behavior of anisotropic consolidated sands. Seismic residual deformations of typical caisson quay walls under different engineering situations are analyzed in detail by the plastic model, and then an index of liquefaction extent is applied to describe the regularity of seismic residual deformation of caisson quay wall top under different engineering situations. Some correlated prediction formulas are derived from the results of regression analysis between seismic residual deformation of quay wall top and extent of liquefaction in the relative safety backfill sand site. Finally, the rationality and the reliability of the prediction methods are validated by test results of a 120 g-centrifuge shaking table, and the comparisons show that some reliable seismic residual deformation of caisson quay can be predicted by appropriate prediction formulas and appropriate index of liquefaction extent.

  9. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    1999-01-01

    In this article two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very offten the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belo...... approximations to the Riemannian metric, and that the subsequent corrections are inherient in the least squares estimation. Keywords: averaging rotations, Riemannian metric, matrix, quaternion......In this article two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very offten the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...

  10. Reinforcement mechanism of multi-anchor wall with double wall facing

    Science.gov (United States)

    Suzuki, Kouta; Kobayashi, Makoto; Miura, Kinya; Konami, Takeharu; Hayashi, Taketo

    2017-10-01

    The reinforced soil wall has high seismic performance as generally known. However, the seismic behavior has not been clarified accurately yet, especially on multi-anchor wall with double wall facing. Indefinite behavior of reinforced soil wall during earthquake make us complicated in case with adopting to the abutment, because of arrangement of anchor plate as reinforcement often different according to the width of roads. In this study, a series of centrifuge model tests were carried out to investigate the reinforcement mechanism of multi anchor wall with double wall facing from the perspective of the vertical earth pressure. Several types of reinforce arrangement and rigid wall were applied in order to verify the arch function in the reinforced regions. The test results show unique behavior of vertical earth pressure, which was affected by arch action. All the vertical earth pressure placed behind facing panel, are larger than that of middle part between facing panel despite of friction between backfill and facing panel. Similar results were obtained in case using rigid wall. On the other hands, the vertical earth pressure, which were measured at the 3cm high from bottom of model container, shows larger than that of bottom. This results show the existence of arch action between double walls. In addition, it implies that the wall facing of such soil structure confined the backfill as pseudo wall, which is very reason that the multi anchor wall with double wall facing has high seismic performance.

  11. Numerical studies of Siberian snakes and spin rotators for RHIC

    International Nuclear Information System (INIS)

    Luccio, A.

    1995-01-01

    For the program of polarized protons in RHIC, two Siberian snakes and four spin rotators per ring will be used. The Snakes will produce a complete spin flip. Spin Rotators, in pairs, will rotate the spin from the vertical direction to the horizontal plane at a given insertion, and back to the vertical after the insertion. Snakes, 180 degrees apart and with their axis of spin precession at 90 degrees to each other, are an effective means to avoid depolarization of the proton beam in traversing resonances. Classical snakes and rotators are made with magnetic solenoids or with a sequence of magnetic dipoles with fields alternately directed in the radial and vertical direction. Another possibility is to use helical magnets, essentially twisted dipoles, in which the field, transverse the axis of the magnet, continuously rotates as the particles proceed along it. After some comparative studies, the authors decided to adopt for RHIC an elegant solution with four helical magnets both for the snakes and the rotators proposed by Shatunov and Ptitsin. In order to simplify the construction of the magnets and to minimize cost, four identical super conducting helical modules will be used for each device. Snakes will be built with four right-handed helices. Spin rotators with two right-handed and two left-handed helices. The maximum field will be limited to 4 Tesla. While small bore helical undulators have been built for free electron lasers, large super conducting helical magnets have not been built yet. In spite of this difficulty, this choice is dictated by some distinctive advantages of helical over more conventional transverse snakes/rotators: (i) the devices are modular, they can be built with arrangements of identical modules, (ii) the maximum orbit excursion in the magnet is smaller, (iii) orbit excursion is independent from the separation between adjacent magnets, (iv) they allow an easier control of the spin rotation and the orientation of the spin precession axis

  12. A new method for measuring the wall charge waveforms of AC PDP

    International Nuclear Information System (INIS)

    Liang Zhihu; Liu Zujun; Liu Chunliang

    2004-01-01

    A new method is developed to measure the wall charge waveforms in coplanar alternating current plasma display panel (AC PDP). In the method, two groups of display electrodes are selected from a coplanar AC PDP and two capacitors are respectively connected with these two groups of display electrodes in series, and a measuring circuit and a reference circuit are thus constructed. With the help of special processing, discharge takes place in the cells included in the measuring circuit under a normal drive voltage but no discharge takes place in the cells included in the reference circuit under a normal drive voltage. The wall charge waveforms are obtained from the voltage difference between the two capacitors. Using the method, the wall charge waveforms are measured during resetting period, addressing period and sustaining period for the 304.8 mm (12-inch) test PDP panel. The result shows that the wall voltage is about 96 V during the sustaining period. (authors)

  13. Analysis of Hydrodynamics and Heat Transfer in a Thin Liquid Film Flowing over a Rotating Disk by Integral Method

    Science.gov (United States)

    Basu, S.; Cetegen, B. M.

    2005-01-01

    An integral analysis of hydrodynamics and heat transfer in a thin liquid film flowing over a rotating disk surface is presented for both constant temperature and constant heat flux boundary conditions. The model is found to capture the correct trends of the liquid film thickness variation over the disk surface and compare reasonably well with experimental results over the range of Reynolds and Rossby numbers covering both inertia and rotation dominated regimes. Nusselt number variation over the disk surface shows two types of behavior. At low rotation rates, the Nusselt number exhibits a radial decay with Nusselt number magnitudes increasing with higher inlet Reynolds number for both constant wall temperature and heat flux cases. At high rotation rates, the Nusselt number profiles exhibit a peak whose location advances radially outward with increasing film Reynolds number or inertia. The results also compare favorably with the full numerical simulation results from an earlier study as well as with the reported experimental results.

  14. Assessment of a method for the prediction of mandibular rotation.

    Science.gov (United States)

    Lee, R S; Daniel, F J; Swartz, M; Baumrind, S; Korn, E L

    1987-05-01

    A new method to predict mandibular rotation developed by Skieller and co-workers on a sample of 21 implant subjects with extreme growth patterns has been tested against an alternative sample of 25 implant patients with generally similar mean values, but with less extreme facial patterns. The method, which had been highly successful in retrospectively predicting changes in the sample of extreme subjects, was much less successful in predicting individual patterns of mandibular rotation in the new, less extreme sample. The observation of a large difference in the strength of the predictions for these two samples, even though their mean values were quite similar, should serve to increase our awareness of the complexity of the problem of predicting growth patterns in individual cases.

  15. Electron transport in the plasma edge with rotating resonant magnetic perturbations at the TEXTOR tokamak

    International Nuclear Information System (INIS)

    Stoschus, Henning

    2011-01-01

    Small three-dimensional (3D) magnetic perturbations can be used as a tool to control the edge plasma parameters in magnetically confined plasmas in high confinement mode (''H-mode'') to suppress edge instabilities inherent to this regime, the Edge Localized Modes (ELMs). In this work, the impact of rotating 3D resonant magnetic perturbation (RMP) fields on the edge plasma structure characterized by electron density and temperature fields is investigated. We study a low confinement (L-mode) edge plasma (r/a>0.9) with high resistivity (edge electron collisionality ν * e >4) at the TEXTOR tokamak. The plasma structure in the plasma edge is measured by a set of high resolution diagnostics: a fast CCD camera (Δt=20 μs) is set up in order to visualize the plasma structure in terms of electron density variations. A supersonic helium beam diagnostic is established as standard diagnostic at TEXTOR to measure electron density n e and temperature T e with high spatial (Δr=2 mm) and temporal resolution (Δt=20 μs). The measured plasma structure is compared to modeling results from the fluid plasma and kinetic neutral transport code EMC3-EIRENE. A sequence of five new observations is discussed: (1) Imaging of electron density variations in the plasma edge shows that a fast rotating RMP field imposes an edge plasma structure, which rotates with the external RMP rotation frequency of vertical stroke ν RMP vertical stroke =1 kHz. (2) Measurements of the electron density and temperature provide strong experimental evidence that in the far edge a rotating 3D scrape-off layer (SOL) exists with helical exhaust channels to the plasma wall components. (3) Radially inward, the plasma structure at the next rational flux surface is found to depend on the relative rotation between external RMP field and intrinsic plasma rotation. For low relative rotation the plasma structure is dominated by a particle and energy loss along open magnetic field lines to the wall components. For high

  16. Electron transport in the plasma edge with rotating resonant magnetic perturbations at the TEXTOR tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Stoschus, Henning

    2011-10-13

    Small three-dimensional (3D) magnetic perturbations can be used as a tool to control the edge plasma parameters in magnetically confined plasmas in high confinement mode (''H-mode'') to suppress edge instabilities inherent to this regime, the Edge Localized Modes (ELMs). In this work, the impact of rotating 3D resonant magnetic perturbation (RMP) fields on the edge plasma structure characterized by electron density and temperature fields is investigated. We study a low confinement (L-mode) edge plasma (r/a>0.9) with high resistivity (edge electron collisionality {nu}{sup *}{sub e}>4) at the TEXTOR tokamak. The plasma structure in the plasma edge is measured by a set of high resolution diagnostics: a fast CCD camera ({delta}t=20 {mu}s) is set up in order to visualize the plasma structure in terms of electron density variations. A supersonic helium beam diagnostic is established as standard diagnostic at TEXTOR to measure electron density n{sub e} and temperature T{sub e} with high spatial ({delta}r=2 mm) and temporal resolution ({delta}t=20 {mu}s). The measured plasma structure is compared to modeling results from the fluid plasma and kinetic neutral transport code EMC3-EIRENE. A sequence of five new observations is discussed: (1) Imaging of electron density variations in the plasma edge shows that a fast rotating RMP field imposes an edge plasma structure, which rotates with the external RMP rotation frequency of vertical stroke {nu}{sub RMP} vertical stroke =1 kHz. (2) Measurements of the electron density and temperature provide strong experimental evidence that in the far edge a rotating 3D scrape-off layer (SOL) exists with helical exhaust channels to the plasma wall components. (3) Radially inward, the plasma structure at the next rational flux surface is found to depend on the relative rotation between external RMP field and intrinsic plasma rotation. For low relative rotation the plasma structure is dominated by a particle and energy loss

  17. Construction Time of Three Wall Types Made of Locally Sourced Materials: A Comparative Study

    OpenAIRE

    Wojciech Drozd; Agnieszka Leśniak; Sebastian Zaworski

    2018-01-01

    Similarly to any other industry, the construction sector puts emphasis on innovativeness, unconventional thinking, and alternative ideas. At present, when sustainable development, ecology, and awareness of people’s impact on the environment grow in importance, low impact buildings can become an innovative alternative construction technology for the highly industrialized construction sector. The paper presents a comparative study of three walls made of available materials used locally, which c...

  18. The global percutaneous shuttling technique tip for arthroscopic rotator cuff repair

    Directory of Open Access Journals (Sweden)

    Bryan G. Vopat

    2014-05-01

    Full Text Available Most arthroscopic rotator cuff repairs utilize suture passing devices placed through arthro- scopic cannulas. These devices are limited by the size of the passing device where the suture is passed through the tendon. An alternative technique has been used in the senior author’s practice for the past ten years, where sutures are placed through the rotator cuff tendon using percutaneous passing devices. This technique, dubbed the global percutaneous shuttling technique of rotator cuff repair, affords the placement of sutures from nearly any angle and location in the shoulder, and has the potential advantage of larger suture bites through the tendon edge. These advantages may increase the area of tendon available to compress to the rotator cuff footprint and improve tendon healing and outcomes. The aim of this study is to describe the global percutaneous shuttling (GPS technique and report our results using this method. The GPS technique can be used for any full thickness rotator cuff tear and is particularly useful for massive cuff tears with poor tissue quality. We recently followed up 22 patients with an average follow up of 32 months to validate its usefulness. American Shoulder and Elbow Surgeons scores improved significantly from 37 preoperatively to 90 postoperatively (P<0.0001. This data supports the use of the GPS technique for arthroscopic rotator cuff repair. Further biomechanical studies are currently being performed to assess the improvements in tendon footprint area with this technique.

  19. Alternative method of retesting UF{sub 6} cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Christ, R. [Nuclear Crago + Service GmbH, Hanau (Germany)

    1991-12-31

    The paper describes an alternative method to perform the periodic inspection of UF{sub 6} cylinders. The hydraulic test is replaced by ultrasonic checking of wall thickness and by magnetic particle testing of all the weld seams. Information about the legal background, the air leak test and the qualification of inspectors is also given.

  20. Remarkable proanthocyanidin adsorption properties of monastrell pomace cell wall material highlight its potential use as an alternative fining agent in red wine production.

    Science.gov (United States)

    Bautista-Ortín, Ana Belén; Ruiz-García, Yolanda; Marín, Fátima; Molero, Noelia; Apolinar-Valiente, Rafael; Gómez-Plaza, Encarna

    2015-01-21

    The existence of interactions between the polysaccharides of vegetal cell walls and proanthocyanins makes this cell wall material an interesting option for its use as a fining agent to reduce the level of proanthocyanins in wines. Pomace wastes from the winery are widely available and a source of cell wall material, and the identification of varieties whose pomace cell walls present high proanthocyanin binding capacity and of processing methods that could enhance their adsorption properties could be of great interest. This study compared the proanthocyanin adsorption properties of pomace cell wall material from three different grape varieties (Monastrell, Cabernet Sauvignon, and Syrah), and the results were compared with those obtained using fresh grape cell walls. Also, the effect of the vinification method has been studied. Analysis of the proanthocyanidins in the solution after reaction with the cell wall material, using phloroglucinolysis and size exclusion chromatography, provided quantitative and qualitative information on the adsorbed and nonadsorbed compounds. A highlight of this study was the observation that Monastrell pomace cell wall material showed a strong affinity for proanthocyanidins, with values similar to that obtained for fresh grapes cell walls, and a preferential binding of high molecular mass proanthocyanidins, so these pomace cell walls could be used in wines to reduce astringency. The use of maceration enzymes during vinification had little effect on the retention capacity of the pomace cell walls obtained from this vinification, although an increase in the retention of low molecular mass proanthocyanidins was observed, and this might have implications for wine sensory properties.

  1. Thermodynamic investigation and optimization of laminar forced convection in a rotating helical tube heat exchanger

    International Nuclear Information System (INIS)

    Shi, Zhongyuan; Dong, Tao

    2014-01-01

    Highlights: • Variation of total entropy generation is investigated parametrically. • Pareto solution sets for heat transfer and flow friction components are obtained. • Dominant irreversibility component and impact of key variables are discussed. - Abstract: Based on the second law of thermodynamics, an entropy generation investigation is carried out under given dimensionless parameters, i.e. heat exchanger duty, heat flux, with respect to heat transfer and frictional pressure drop in a rotating helical tube heat exchanger with laminar convective flow. The entropy generation from heat transfer across a finite temperature difference – Ψ h decreases with increasing Dean number which represents the impact of centrifugal force induced secondary flow in enhancing heat transfer. Another aspect of increasing Dean number is that intensified momentum transfer in the radial direction also raises the entropy generation from frictional pressure drop – Ψ f , the superposed effect of which yields a decreasing–increasing trend of the total entropy generation-Ψ, a local minimum located in between. The rotation of the helical tube in streamwise (co-rotation) or counter streamwise (counter-rotation) direction leads to a decrease in Ψ h and a increase in Ψ f which complicates the situation that whether or where the minimum of total entropy generation exists is dependent on whether Ψ is dominated by Ψ h or Ψ f or somewhere in between. No difference is discerned between pairs of cases with constant wall temperature and uniform wall heat flux but the same set of variables and parameters. A multi-objective optimization targeting Ψ h and Ψ f simultaneously is implemented using the non-dominated sorting genetic algorithm II (NSGA II). Five solution sets are selected and compared with the conventional optimization in regard of Ψ distinguishing the Ψ h -dominated region from the Ψ f -dominated region, the dimensionless variable η 1 is found to be the most suitable

  2. Estimating adipose tissue in the chest wall using ultrasonic and alternate 40K and biometric measurements

    International Nuclear Information System (INIS)

    Anderson, A.L.; Campbell, G.W.; Singh, M.S.

    1982-01-01

    The percentage of adipose (fat) tissue in the chest wall must be known to accurately measure Pu in the human lung. Correction factors of 100% or more in X-ray detection efficiency are common in a normal population of individuals of differing body composition and have been determined in the past by means of elaborate and costly ultrasonic measurements of the subject's chest. Methods using simple 40 K and biometric measurement techniques have been investigated to determine the adipose content in the human chest wall. These methods compare favorably with ultrasonic measurements and allow laboratories not possessing ultrasonic equipment to make appropriate corrections for x-ray detection efficiency. These methods predict adipose content to within 15% of the absolute ultrasonic value. (author)

  3. Entropy of a rotating and charged black string to all orders in the Planck length

    International Nuclear Information System (INIS)

    Ren, Zhao; Yue-Qin, Wu; Li-Chun, Zhang

    2009-01-01

    By using the entanglement entropy method, this paper calculates the statistical entropy of the Bose and Fermi fields in thin films, and derives the Bekenstein–Hawking entropy and its correction term on the background of a rotating and charged black string. Here, the quantum field is entangled with quantum states in the black string and thin film to the event horizon from outside the rotating and charged black string. Taking into account the effect of the generalized uncertainty principle on quantum state density, it removes the difficulty of the divergence of state density near the event horizon in the brick-wall model. These calculations and discussions imply that high density quantum states near the event horizon of a black string are strongly correlated with the quantum states in a black string and that black string entropy is a quantum effect. The ultraviolet cut-off in the brick-wall model is not reasonable. The generalized uncertainty principle should be considered in the high energy quantum field near the event horizon. From the viewpoint of quantum statistical mechanics, the correction value of Bekenstein–Hawking entropy is obtained. This allows the fundamental recognition of the correction value of black string entropy at nonspherical coordinates

  4. Nondestructive evaluation of wall thinning occurred under reinforced plate by MFL method

    International Nuclear Information System (INIS)

    Kikuchi, Hiroaki; Sato, Kaito; Shimizu, Isamu

    2013-01-01

    Basic study on applying magnetic flux leakage (MFL) method using ac excitation to a nondestructive evaluation of wall thinning occurred under reinforcing plates in nuclear power plants were performed. Frequently, MFL method by means of dc field for exciting specimens is adopted, and only intensity of magnetic flux density is evaluated. On the other hand, MFL with alternating current enable us to utilize not only amplitude of magnetic flux density but also phase difference, which contributes to evaluation with higher accuracy. Here, specimens with slit and pipe with imitated wall thinning are prepared and magnetized using magnetic yoke with ac field, and then the leakage magnetic flux density and the phase difference on the specimen surface are investigated. Additionally, specimens imitated wall thinning occurred under reinforcing plates were investigated by MFL with ac excitation. (author)

  5. Faraday Rotation for SMOS Retrievals of Ocean Salinity and Soil Moisture

    Science.gov (United States)

    El-Nimri, Salem; Le Vine, David M.

    2016-01-01

    Faraday rotation is a change in polarization as radiation propagates from the surface through the ionosphere to the sensor. At L-band (1.4 GHz) this change can be significant and can be important for the remote sensing of soil moisture and ocean salinity from space. Consequently, modern L-band radiometers (SMOS, Aquarius and SMOS) are polarimetric to measure Faraday rotation in situ so that a correction can be made. This is done using the ratio of the third and second Stokes parameters. In the case of SMOS this procedure has produced very noisy estimates. An alternate procedure is reported here in which the total electron content is estimated and averaged to reduce noise.

  6. Second sound shock waves in rotating superfluid helium

    International Nuclear Information System (INIS)

    Torczynski, J.R.

    1983-01-01

    Second sound shock waves have been used to examine the breakdown of superfluidity in bulk He II. The maximum counterflow velocity achieved in this manner was measured at a variety of temperatures and pressures. The results are found to agree with predictions of vortex nucleation theories (Langer and Fisher, 1967) in their pressure and temperature dependences although it was shown that dissipation occurred only near the heater. A simple scaling argument is suggested, assuming breakdown occurs near the heater. A vortex dynamics model of breakdown (following the method of Turner, private communication) is developed. To examine the effect of vorticity on breakdown, second sound shocks were produced in rotating helium. Experiments were performed in which the shocks propagated either along or normal to the axis of rotation, called axial and transverse cases, respectively. In both cases the decay was seen to increase monotonically with the rotation rate. Furthermore, the decay was ongoing rather than being confined to a narrow region near the heater. However, the extraordinary dissipation in the transverse case seemed to be related primarily to the arrival of secondary waves from the heater-sidewall boundary. An explanation of this difference is put forth in terms of vortex nucleation in the bulk fluid, using ideas similar to Crocco's Theorem. In order to examine the breakdown of superfluidity away from walls in nonrotation fluid, spherically converging second shocks were produced. The temperature jumps of the waves were measured, and exact numerical solutions of the two-fluid jump conditions (Moody, 1983) were used to calculate the relative velocity in each case

  7. The local domain wall position in ferromagnetic thin wires: simultaneous measurement of resistive and transverse voltages at multiple points

    International Nuclear Information System (INIS)

    Hanada, R.; Sugawara, H.; Aoki, Y.; Sato, H.; Shigeto, K.; Shinjo, T.; Ono, T.; Miyajima, H.

    2002-01-01

    We have simultaneously measured the field dependences of voltages at multiple pairs of resistance and transverse voltage probes in ferromagnetic wires (with either magnetic or non-magnetic voltage probes). Both the resistive (through the giant magnetoresistance and anisotropic magnetoresistance) and transverse voltages (through the planar Hall effect) exhibit abrupt jumps, reflecting discrete motion of domain walls or rotations of magnetization. Voltage probes, even if non-magnetic, are found to affect the jump fields depending on the sample conditions. We demonstrate that the specific information on the domain (wall) motion along a thin ferromagnetic wire could be obtained from the jump fields. (author)

  8. Alternatives for water basin spent fuel storage: executive summary and comparative evaluation

    International Nuclear Information System (INIS)

    Viebrock, J.M.

    1979-09-01

    A five part report identifies and evaluates alternatives to conventional methods for water basin storage of irradiated light water reactor fuel assemblies (spent fuel). A recommendation is made for development or further evaluation of one attractive alternative: Proceed to develop fuel disassembly with subsequent high density storage of fuel pins (pin storage). The storage alternatives were evaluated for emplacement at reactor, in existing away-from-reactor storage facilities and in new away-from-reactor facilities. In the course of the study, the work effort necessarily extended beyond the pool wall in scope to properly assess the affects of storage alternatives on AFT systems

  9. Nernst Theorem and Statistical Entropy of 5-Dimensional Rotating Black Hole

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ren; WU Yue-Qin; ZHANG Li-Chun

    2003-01-01

    In this paper, by using quantum statistical method, we obtain the partition function of Bose field and Fermi field on the background of the 5-dimensional rotating black hole. Then via the improved brick-wall method and membrane model, we calculate the entropy of Bose field and Fermi field of the black hole. And it is obtained that the entropy of the black hole is not only related to the area of the outer horizon but also is the function of inner horizon's area. In our results, there are not the left out term and the divergent logarithmic term in the original brick-wall method.The doubt that why the entropy of the scalar or Dirac field outside the event horizon is the entropy of the black hole in the original brick-wall method does not exist. The influence of spinning degeneracy of particles on entropy of the black hole is also given. It is shown that the entropy determined by the areas of the inner and outer horizons will approach zero,when the radiation temperature of the black hole approaches absolute zero. It satisfies Nernst theorem. The entropy can be taken as the Planck absolute entropy. We provide a way to study higher dimensional black hole.

  10. Steady flow instability in an annulus with deflectors at rotational vibration

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, Nikolai V [Lab. Vibrational Hydromechanics, Perm State-Humanitarian Pedagogical University 24 Sibirskaya av., 614990 Perm (Russian Federation); Pareau, Dominique; Stambouli, Moncef [Lab. Chemical Engineering, CentraleSupélec-Université Paris Saclay, Grande Voie des Vignes, 92295 Châtenay-Malabry (France); Ivantsov, Andrey, E-mail: kozlov.n@icmm.ru [Lab. Computational Hydrodynamics Institute of Continuous Media Mechanics UB RAS1 Acad. Korolev st., 614013 Perm (Russian Federation)

    2016-12-15

    Experimental study and direct numerical simulation of the dynamics of an isothermal low-viscosity fluid are done in a coaxial gap of a cylindrical container making rotational vibrations relative to its axis. On the inner surface of the outer wall of the container, semicircular deflectors are regularly situated, playing the role of flow activators. As a result of vibrations, the activators oscillate tangentially. In the simulation, a 2D configuration is considered, excluding the end-wall effects. In the experiment, a container with a large aspect ratio is used. Steady streaming is generated in the viscous boundary layers on the activators. On each of the latter, beyond the viscous domain, a symmetric vortices pair is formed. The steady streaming in the annulus has an azimuthal periodicity. With an increase in the vibration intensity, a competition between the vortices occurs, as a result of which one of the vortices (let us call it even) approaches the activator and the other one (odd) rolls away and couples with the vortices from the neighbouring pairs. Streamlines of the odd vortices close on each other, forming a cog-wheel shaped flow that encircles the inner wall. Comparison of the experiment and the simulation reveals an agreement at moderate vibration intensity. (paper)

  11. Perceptual strategies of pigeons to detect a rotational centre--a hint for star compass learning?

    Directory of Open Access Journals (Sweden)

    Bianca Alert

    Full Text Available Birds can rely on a variety of cues for orientation during migration and homing. Celestial rotation provides the key information for the development of a functioning star and/or sun compass. This celestial compass seems to be the primary reference for calibrating the other orientation systems including the magnetic compass. Thus, detection of the celestial rotational axis is crucial for bird orientation. Here, we use operant conditioning to demonstrate that homing pigeons can principally learn to detect a rotational centre in a rotating dot pattern and we examine their behavioural response strategies in a series of experiments. Initially, most pigeons applied a strategy based on local stimulus information such as movement characteristics of single dots. One pigeon seemed to immediately ignore eccentric stationary dots. After special training, all pigeons could shift their attention to more global cues, which implies that pigeons can learn the concept of a rotational axis. In our experiments, the ability to precisely locate the rotational centre was strongly dependent on the rotational velocity of the dot pattern and it crashed at velocities that were still much faster than natural celestial rotation. We therefore suggest that the axis of the very slow, natural, celestial rotation could be perceived by birds through the movement itself, but that a time-delayed pattern comparison should also be considered as a very likely alternative strategy.

  12. Investigation of the Hygrothermal Performance of Alternative Insulation Materials

    DEFF Research Database (Denmark)

    Rode, Carsten; Kristiansen, Finn Harken; Rasmussen, Niels T.

    1999-01-01

    The paper gives an account of hygrothermal investigations carried out on some insulation products which are "alternative" to the ones that are traditionally used in Danish constructions. The alternative products are claimed to be friendly both to the environment and to the labour force. The mater......The paper gives an account of hygrothermal investigations carried out on some insulation products which are "alternative" to the ones that are traditionally used in Danish constructions. The alternative products are claimed to be friendly both to the environment and to the labour force...... is determined for the different materials with a guarded hot plate apparatus in which different vapour pressure conditions can be maintained over the specimens. The apparatus and some results are presented.2. Computational analysis of the hygrothermal performance of constructions with alternative insulation...... products.The hygrothermal performance of constructions with alternative insulation products is analysed with a computational model for combined heat and moisture transfer. The analysis concerns both traditional wall and roof constructions with the alternative insulation products, and some alternative...

  13. A New High-Resolution Spectral Approach to Noninvasively Evaluate Wall Deformations in Arteries

    Directory of Open Access Journals (Sweden)

    Ivonne Bazan

    2014-01-01

    Full Text Available By locally measuring changes on arterial wall thickness as a function of pressure, the related Young modulus can be evaluated. This physical magnitude has shown to be an important predictive factor for cardiovascular diseases. For evaluating those changes, imaging segmentation or time correlations of ultrasonic echoes, coming from wall interfaces, are usually employed. In this paper, an alternative low-cost technique is proposed to locally evaluate variations on arterial walls, which are dynamically measured with an improved high-resolution calculation of power spectral densities in echo-traces of the wall interfaces, by using a parametric autoregressive processing. Certain wall deformations are finely detected by evaluating the echoes overtones peaks with power spectral estimations that implement Burg and Yule Walker algorithms. Results of this spectral approach are compared with a classical cross-correlation operator, in a tube phantom and “in vitro” carotid tissue. A circulating loop, mimicking heart periods and blood pressure changes, is employed to dynamically inspect each sample with a broadband ultrasonic probe, acquiring multiple A-Scans which are windowed to isolate echo-traces packets coming from distinct walls. Then the new technique and cross-correlation operator are applied to evaluate changing parietal deformations from the detection of displacements registered on the wall faces under periodic regime.

  14. A New High-Resolution Spectral Approach to Noninvasively Evaluate Wall Deformations in Arteries

    Science.gov (United States)

    Bazan, Ivonne; Negreira, Carlos; Ramos, Antonio; Brum, Javier; Ramirez, Alfredo

    2014-01-01

    By locally measuring changes on arterial wall thickness as a function of pressure, the related Young modulus can be evaluated. This physical magnitude has shown to be an important predictive factor for cardiovascular diseases. For evaluating those changes, imaging segmentation or time correlations of ultrasonic echoes, coming from wall interfaces, are usually employed. In this paper, an alternative low-cost technique is proposed to locally evaluate variations on arterial walls, which are dynamically measured with an improved high-resolution calculation of power spectral densities in echo-traces of the wall interfaces, by using a parametric autoregressive processing. Certain wall deformations are finely detected by evaluating the echoes overtones peaks with power spectral estimations that implement Burg and Yule Walker algorithms. Results of this spectral approach are compared with a classical cross-correlation operator, in a tube phantom and “in vitro” carotid tissue. A circulating loop, mimicking heart periods and blood pressure changes, is employed to dynamically inspect each sample with a broadband ultrasonic probe, acquiring multiple A-Scans which are windowed to isolate echo-traces packets coming from distinct walls. Then the new technique and cross-correlation operator are applied to evaluate changing parietal deformations from the detection of displacements registered on the wall faces under periodic regime. PMID:24688596

  15. Error Field Assessment from Driven Mode Rotation: Results from Extrap-T2R Reversed-Field-Pinch and Perspectives for ITER

    Science.gov (United States)

    Volpe, F. A.; Frassinetti, L.; Brunsell, P. R.; Drake, J. R.; Olofsson, K. E. J.

    2012-10-01

    A new ITER-relevant non-disruptive error field (EF) assessment technique not restricted to low density and thus low beta was demonstrated at the Extrap-T2R reversed field pinch. Resistive Wall Modes (RWMs) were generated and their rotation sustained by rotating magnetic perturbations. In particular, stable modes of toroidal mode number n=8 and 10 and unstable modes of n=1 were used in this experiment. Due to finite EFs, and in spite of the applied perturbations rotating uniformly and having constant amplitude, the RWMs were observed to rotate non-uniformly and be modulated in amplitude (in the case of unstable modes, the observed oscillation was superimposed to the mode growth). This behavior was used to infer the amplitude and toroidal phase of n=1, 8 and 10 EFs. The method was first tested against known, deliberately applied EFs, and then against actual intrinsic EFs. Applying equal and opposite corrections resulted in longer discharges and more uniform mode rotation, indicating good EF compensation. The results agree with a simple theoretical model. Extensions to tearing modes, to the non-uniform plasma response to rotating perturbations, and to tokamaks, including ITER, will be discussed.

  16. Effect of pool rotation on three-dimensional flow in a shallow annular pool of silicon melt with bidirectional temperature gradients

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Quan-Zhuang; Peng, Lan; Liu, Jia [Key Laboratory of Low-grade Energy Utilization Technologies and Systems of Ministry of Education, College of Power Engineering, Chongqing University, Chongqing, 400044 (China); Wang, Fei, E-mail: penglan@cqu.edu.cn [Chongqing Special Equipment Inspection and Research Institute, Chongqing, 401121 (China)

    2016-08-15

    In order to understand the effect of pool rotation on silicon melt flow with the bidirectional temperature gradients, we conducted a series of unsteady three-dimensional (3D) numerical simulations in a shallow annular pool. The bidirectional temperature gradients are produced by the temperature difference between outer and inner walls as well as a constant heat flux at the bottom. Results show that when Marangoni number is small, a 3D steady flow is common without pool rotation. But it bifurcates to a 3D oscillatory flow at a low rotation Reynolds number. Subsequently, the flow becomes steady and axisymmetric at a high rotation Reynolds number. When the Marangoni number is large, pool rotation can effectively suppress the temperature fluctuation on the free surface, meanwhile, it improves the flow stability. The critical heat flux density diagrams are mapped, and the effects of radial and vertical temperature gradients on the flow are discussed. Additionally, the transition process from the flow dominated by the radial temperature gradient to the one dominated by the vertical temperature gradient is presented. (paper)

  17. Asteroid rotation rates

    International Nuclear Information System (INIS)

    Binzel, R.P.; Farinella, P.

    1989-01-01

    Within the last decade the data base of asteroid rotation parameters (rotation rates and lightcurve amplitudes) has become sufficiently large to identify some definite rends and properties which can help us to interpret asteroid collisional evolution. Many significant correlations are found between rotation parameters and diameter, with distinct changes occurring near 125 km. The size range, which is also the diameter above which self-gravity may become important, perhaps represents a division between surviving primordial asteroids and collisional fragments. A Maxwellian is able to fit the observed rotation rate distributions of asteroids with D>125 km, implying that their rotation rates may be determined by collisional evolution. Asteroids with D<125 km show an excess of slow rotators and their non-Maxwellian distributions suggests that their rotation rates are more strongly influenced by other processes, such as the distribution resulting from their formation in catastrophic disruption events. Other correlations observed in the data set include different mean rotation rates for C, S and M type asteroids implying that their surface spectra are indicative of bulk properties

  18. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    2001-01-01

    In this paper two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very often the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong ...... approximations to the Riemannian metric, and that the subsequent corrections are inherent in the least squares estimation.......In this paper two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very often the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...

  19. Place Atrium to Water Seal (PAWS): Assessing Wall Suction Versus No Suction for Chest Tubes After Open Heart Surgery.

    Science.gov (United States)

    Kruse, Tamara; Wahl, Sharon; Guthrie, Patricia Finch; Sendelbach, Sue

    2017-08-01

    Traditionally chest tubes are set to -20 cm H 2 O wall suctioning until removal to facilitate drainage of blood, fluid, and air from the pleural or mediastinal space in patients after open heart surgery. However, no clear evidence supports using wall suction in these patients. Some studies in patients after pulmonary surgery indicate that using chest tubes with a water seal is safer, because this practice decreases duration of chest tube placement and eliminates air leaks. To show that changing chest tubes to a water seal after 12 hours of wall suction (intervention) is a safe alternative to using chest tubes with wall suction until removal of the tubes (usual care) in patients after open heart surgery. A before-and-after quality improvement design was used to evaluate the differences between the 2 chest tube management approaches in chest tube complications, output, and duration of placement. A total of 48 patients received the intervention; 52 received usual care. The 2 groups (intervention vs usual care) did not differ significantly in complications (0 vs 2 events; P = .23), chest tube output (H 1 = 0.001, P = .97), or duration of placement (median, 47 hours for both groups). Changing chest tubes from wall suction to water seal after 12 hours of wall suction is a safe alternative to using wall suctioning until removal of the tubes. ©2017 American Association of Critical-Care Nurses.

  20. Wind tunnels with adapted walls for reducing wall interference

    Science.gov (United States)

    Ganzer, U.

    1979-01-01

    The basic principle of adaptable wind tunnel walls is explained. First results of an investigation carried out at the Aero-Space Institute of Berlin Technical University are presented for two dimensional flexible walls and a NACA 0012 airfoil. With five examples exhibiting very different flow conditions it is demonstrated that it is possible to reduce wall interference and to avoid blockage at transonic speeds by wall adaptation.

  1. Chaotic fluid mixing by alternating microparticle topologies to enhance biochemical reactions

    NARCIS (Netherlands)

    Gao, Y.; Reenen, van A.; Hulsen, M.A.; Jong, de A.M.; Prins, M.W.J.; Toonder, den J.M.J.

    2014-01-01

    We report experimental results on chaotic mass transport induced by alternating topological changes of magnetic particle chains actuated by a rotating magnetic field. Results on the induced fluid flows, through particle tracing experiments and mixing experiments, are obtained for (1) the regime of

  2. Inverse measurement of wall pressure field in flexible-wall wind tunnels using global wall deformation data

    Science.gov (United States)

    Brown, Kenneth; Brown, Julian; Patil, Mayuresh; Devenport, William

    2018-02-01

    The Kevlar-wall anechoic wind tunnel offers great value to the aeroacoustics research community, affording the capability to make simultaneous aeroacoustic and aerodynamic measurements. While the aeroacoustic potential of the Kevlar-wall test section is already being leveraged, the aerodynamic capability of these test sections is still to be fully realized. The flexibility of the Kevlar walls suggests the possibility that the internal test section flow may be characterized by precisely measuring small deflections of the flexible walls. Treating the Kevlar fabric walls as tensioned membranes with known pre-tension and material properties, an inverse stress problem arises where the pressure distribution over the wall is sought as a function of the measured wall deflection. Experimental wall deformations produced by the wind loading of an airfoil model are measured using digital image correlation and subsequently projected onto polynomial basis functions which have been formulated to mitigate the impact of measurement noise based on a finite-element study. Inserting analytic derivatives of the basis functions into the equilibrium relations for a membrane, full-field pressure distributions across the Kevlar walls are computed. These inversely calculated pressures, after being validated against an independent measurement technique, can then be integrated along the length of the test section to give the sectional lift of the airfoil. Notably, these first-time results are achieved with a non-contact technique and in an anechoic environment.

  3. Sex differences and autism: brain function during verbal fluency and mental rotation.

    Directory of Open Access Journals (Sweden)

    Felix D C C Beacher

    Full Text Available Autism spectrum conditions (ASC affect more males than females. This suggests that the neurobiology of autism: 1 may overlap with mechanisms underlying typical sex-differentiation or 2 alternately reflect sex-specificity in how autism is expressed in males and females. Here we used functional magnetic resonance imaging (fMRI to test these alternate hypotheses. Fifteen men and fourteen women with Asperger syndrome (AS, and sixteen typically developing men and sixteen typically developing women underwent fMRI during performance of mental rotation and verbal fluency tasks. All groups performed the tasks equally well. On the verbal fluency task, despite equivalent task-performance, both males and females with AS showed enhanced activation of left occipitoparietal and inferior prefrontal activity compared to controls. During mental rotation, there was a significant diagnosis-by-sex interaction across occipital, temporal, parietal, middle frontal regions, with greater activation in AS males and typical females compared to AS females and typical males. These findings suggest a complex relationship between autism and sex that is differentially expressed in verbal and visuospatial domains.

  4. Sex differences and autism: brain function during verbal fluency and mental rotation.

    Science.gov (United States)

    Beacher, Felix D C C; Radulescu, Eugenia; Minati, Ludovico; Baron-Cohen, Simon; Lombardo, Michael V; Lai, Meng-Chuan; Walker, Anne; Howard, Dawn; Gray, Marcus A; Harrison, Neil A; Critchley, Hugo D

    2012-01-01

    Autism spectrum conditions (ASC) affect more males than females. This suggests that the neurobiology of autism: 1) may overlap with mechanisms underlying typical sex-differentiation or 2) alternately reflect sex-specificity in how autism is expressed in males and females. Here we used functional magnetic resonance imaging (fMRI) to test these alternate hypotheses. Fifteen men and fourteen women with Asperger syndrome (AS), and sixteen typically developing men and sixteen typically developing women underwent fMRI during performance of mental rotation and verbal fluency tasks. All groups performed the tasks equally well. On the verbal fluency task, despite equivalent task-performance, both males and females with AS showed enhanced activation of left occipitoparietal and inferior prefrontal activity compared to controls. During mental rotation, there was a significant diagnosis-by-sex interaction across occipital, temporal, parietal, middle frontal regions, with greater activation in AS males and typical females compared to AS females and typical males. These findings suggest a complex relationship between autism and sex that is differentially expressed in verbal and visuospatial domains.

  5. 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.

  6. Surface anisotropy of Cr xN1-x films prepared on an inner wall by magnetic sputtering

    International Nuclear Information System (INIS)

    Zeng, F.; Liang, R.; Li, X.W.; Wen, S.P.; Gao, Y.; Gu, Y.L.; Pan, F.

    2007-01-01

    The Cr x N 1-x films were prepared by magnetic sputtering on an inner wall of a column. Their surface morphologies were studied by atomic force microscopy (AFM) and found to be anisotropic. The 3-D AFM images indicate the grains grow upward along the rotational axis of the system. The AFM top views show a mosaic-like pattern for all samples. Analysis of the height-height correlation function demonstrates that correlation length along the rotational axis of the system is longer than that vertical to the axis. The correlation length and RMS roughness increase with the flow rate of N 2 . A deposition model proposed that the shadowing effect of the reactive gas N 2 is the dominant factor for surface anisotropy. The bias added on the substrate is regarded to modulate the grain direction to the rotation axis and enhance roughness and defects

  7. Resistive wall modes and error field amplification

    International Nuclear Information System (INIS)

    Boozer, Allen H.

    2003-01-01

    Resistive wall modes and the rapid damping of plasma rotation by the amplification of magnetic field errors are related physical phenomena that affect the performance of the advanced tokamak and spherical torus plasma confinement devices. Elements of our understanding of these phenomena and the code that is used to design the major experimental facilities are based on the electrical circuit representation of the response of the plasma to perturbations. Although the circuit representation of the plasma may seem heuristic, this representation can be rigorously obtained using Maxwell's equations and linearity for plasmas that evolve on a disparate time scale from that of external currents. These and related results are derived. In addition methods are given for finding the plasma information that the circuit representation requires using post-processors for codes that calculate perturbed plasma equilibria

  8. Stellar Evolution with Rotation: Mixing Processes in AGB Stars

    Science.gov (United States)

    Driebe, T.; Blöcker, T.

    We included diffusive angular momentum transport and rotationally induced mixing processes in our stellar evolution code and studied the influence of rotation on the evolution of intermediate mass stars (M*=2dots6 Msolar) towards and along the asymptotic giant branch (AGB). The calculations start in the fully convective pre-main sequence phase and the initial angular momentu m was adjusted such that on the zero-age main sequence vrot=200 km/ s is achieved. The diffusion coefficients for the five rotational instabilities considered (dynamical shear, secular shear, Eddington-Sweet (ES) circulation, Solberg-Høiland-instability and Goldreich-Schubert-Fricke (GSF) instability) were adopted from Heger et al. (2000, ApJ 528, 368). Mixing efficiency and sensitivity of these processes against molecular weight gradients have been determined by calibration of the main sequence width. In this study we focus on the abundance evolution of carbon. On the one hand, the surface abundance ratios of 12C/13C a nd 12C/16O at the base of the AGB were found to be ≈ 7dots 10 and ≈ 0.1, resp., being a factor of two lower than in non-rotating models. This results from the slow but continuously operating rotationally induced mixing due to the ES-circulation and the GSF-instability during the long main sequence phase. On the other hand, 13C serves as neutron source for interior s-process nucleosynthesis in AGB stars vi a 13C(α,n)16O. Herwig et al. (1997, A&A 324, L81) found that a 13C pocket is forme d in the intershell region of 3 Msolar AGB star if diffusive overshoot is considered. Our calculations show, that mixing processes due to rotation open an alternative channel for the formation of a 13C pocket as found by Langer et al. (1999, A&A 346, L37). Again, ES-circulation and GSF-instability are the predominant rotational mixing processes.

  9. Shear-stress-induced structural arrangement of water molecules in nanoscale Couette flow with slipping at wall boundary

    International Nuclear Information System (INIS)

    Lin, Jau-Wen

    2014-01-01

    This study investigated the structuring of water molecules in a nanoscale Couette flow with the upper plate subjected to lateral forces with various magnitudes and water slipping against a metal wall. It was found that when the upper plate is subjected to a force, the water body deforms into a parallelepiped. Water molecules in the channel are then gradually arranged into lattice positions, creating a layered structure. The structural arrangement of water molecules is caused by the water molecules accommodating themselves to the increase in energy under the application of a lateral force on the moving plate. The ordering arrangement of water molecules increases the rotational degree of freedom, allowing the molecules to increase their Coulomb potential energy through polar rotation that accounts for the energy input through the upper plate. With a force continuously applied to the upper plate, the water molecules in contact with the upper plate move forward until slip between the water and upper plate occurs. The relation between the structural arrangement of water molecules, slip at the wall, and the shear force is studied. The relation between the slip and the locking/unlocking of water molecules to metal atoms is also studied

  10. Polarized excitons and optical activity in single-wall carbon nanotubes

    Science.gov (United States)

    Chang, Yao-Wen; Jin, Bih-Yaw

    2018-05-01

    The polarized excitons and optical activity of single-wall carbon nanotubes (SWNTs) are studied theoretically by π -electron Hamiltonian and helical-rotational symmetry. By taking advantage of the symmetrization, the single-particle energy and properties of a SWNT are characterized with the corresponding helical band structure. The dipole-moment matrix elements, magnetic-moment matrix elements, and the selection rules can also be derived. Based on different selection rules, the optical transitions can be assigned as the parallel-polarized, left-handed circularly-polarized, and right-handed circularly-polarized transitions, where the combination of the last two gives the cross-polarized transition. The absorption and circular dichroism (CD) spectra are simulated by exciton calculation. The calculated results are well comparable with the reported measurements. Built on the foundation, magnetic-field effects on the polarized excitons and optical activity of SWNTs are studied. Dark-bright exciton splitting and interband Faraday effect in the CD spectrum of SWNTs under an axial magnetic field are predicted. The Faraday rotation dispersion can be analyzed according to the selection rules of circular polarizations and the helical band structure.

  11. Rotator cuff exercises

    Science.gov (United States)

    ... 25560729 . Read More Frozen shoulder Rotator cuff problems Rotator cuff repair Shoulder arthroscopy Shoulder CT scan Shoulder MRI scan Shoulder pain Patient Instructions Rotator cuff - self-care Shoulder surgery - discharge Using your ...

  12. Experimental and numerical investigations of higher mode effects on seismic inelastic response of reinforced concrete shear walls

    Science.gov (United States)

    Ghorbanirenani, Iman

    This thesis presents two experimental programs together with companion numerical studies that were carried out on reinforced concrete shear walls: static tests and dynamic (shake table) tests. The first series of experiments were monotonic and cyclic quasi-static testing on ductile reinforced concrete shear wall specimens designed and detailed according to the seismic provisions of NBCC 2005 and CSA-A23.3-04 standard. The tests were carried out on full-scale and 1:2.37 reduced scale wall specimens to evaluate the seismic design provisions and similitude law and determine the appropriate scaling factor that could be applied for further studies such as dynamic tests. The second series of experiments were shake table tests conducted on two identical 1:2.33 scaled, 8-storey moderately ductile reinforced concrete shear wall specimens to investigate the effects of higher modes on the inelastic response of slender walls under high frequency ground motions expected in Eastern North America. The walls were designed and detailed according to the seismic provisions of NBCC 2005 and CSA-A23.3-04 standard. The objectives were to validate and understand the inelastic response and interaction of shear, flexure and axial loads in plastic hinge zones of the walls considering the higher mode effects and to investigate the formation of second hinge in upper part of the wall due to higher mode responses. Second mode response significantly affected the response of the walls. This caused inelastic flexural response to develop at the 6th level with approximately the same rotation ductility compared to that observed at the base. Dynamic amplification of the base shear forces was also observed in both walls. Numerical modeling of these two shake table tests was performed to evaluate the test results and validate current modeling approaches. Nonlinear time history analyses were carried out by the reinforced concrete fibre element (OpenSees program) and finite element (VecTor2 program

  13. Theoretical analysis of the influence of flexoelectric effect on the defect site in nematic inversion walls

    International Nuclear Information System (INIS)

    Zheng Gui-Li; Xuan Li; Zhang Hui; Ye Wen-Jiang; Zhang Zhi-Dong; Song Hong-Wei

    2016-01-01

    Based on the experimental phenomena of flexoelectric response at defect sites in nematic inversion walls conducted by Kumar et al., we gave the theoretical analysis using the Frank elastic theory. When a direct-current electric field normal to the plane of the substrate is applied to the parallel aligned nematic liquid crystal cell with weak anchoring, the rotation of ±1 defects in the narrow inversion walls can be exhibited. The free energy of liquid crystal molecules around the +1 and –1 defect sites in the nematic inversion walls under the electric field was formulated and the electric-field-driven structural changes at the defect site characterized by polar and azimuthal angles of the local director were simulated. The results reveal that the deviation of azimuthal angle induced by flexoelectric effect are consistent with the switching of extinction brushes at the +1 and −1 defects obtained in the experiment conducted by Kumar et al. (paper)

  14. Nutrient enhanced short rotation coppice for biomass in central Wales

    Energy Technology Data Exchange (ETDEWEB)

    Hodson, R.W.; Slater, F.M.; Lynn, S.F.; Randerson, P.F. [Univ. of Wales (United Kingdom)

    1993-12-31

    Two projects involving short rotation willow coppice are taking place on the eastern side of the Cambrian Mountains in central Wales. One project examines, as an alternative land use, the potential of short rotation willow coppice variously enhanced by combinations of lime, phosphorous and potassium fertilizers and also digested sewage sludge on an acidic upland site at an altitude of 260m. The first year results of this project are described in detail, showing the necessity for limestone additions and also demonstrating that of the four willow varieties established, Salix dasyclados is the only possible, profitable fuel crop. The other project involving willow in a filter bed system is outlined along with an additional project investigating the effect of sewage sludge additions on the Rubus fruticosus production in a birch dominated mixed deciduous woodland.

  15. Solid state engine with alternating motion

    Science.gov (United States)

    Golestaneh, Ahmad A.

    1982-01-01

    Heat energy is converted to mechanical motion utilizing apparatus including a cylinder, a piston having openings therein reciprocable in the cylinder, inlet and outlet ports for warm water at one end of the cylinder, inlet and outlet ports for cool water at the other end of the cylinder, gates movable with the piston and slidably engaging the cylinder wall to alternately open and close the warm and cool water ports, a spring bearing against the warm water side of the piston and a double helix of a thermal shape memory material attached to the cool end of the cylinder and to the piston. The piston is caused to reciprocate by alternately admitting cool water and warm water to the cylinder.

  16. On Physical Interpretation of the In-Site Measurement of Earth Rotation by Ring Laser Gyrometers

    Science.gov (United States)

    Chao, B. F.

    2004-01-01

    Large ring laser gyrometers under development have demonstrated the capability of detecting minute ground motions and deformations on a wide range of timescales. The next challenge and goal is to measure the Earth's rotation variations to a precision that rivals that of the present space-geodesy techniques, thus providing an in-situ (and cost effective alternatives of Earth rotation measurement for geophysical research and geodetic applications. Aside from thermal and mechanical instabilities, "undesirable" ground motion and tilt that appear in the signal will need to be removed before any variation in Earth rotation can be detected. Removal of these signals, some of them are larger than the sought rotation signals, has been a typical procedure in many precise geophysical instruments, such as gravimeters, seismometers, and tiltmeters. The remaining Earth rotation signal resides in both the spin around the axis and in the orientation of the axis. In the case of the latter, the in-situ measurement is complementary to the space-geodetic observables in terms of polar motion and nutation, a fact to be exploited.

  17. Seismic performance evaluation of an infilled rocking wall frame structure through quasi-static cyclic testing

    Science.gov (United States)

    Pan, Peng; Wu, Shoujun; Wang, Haishen; Nie, Xin

    2018-04-01

    Earthquake investigations have illustrated that even code-compliant reinforced concrete frames may suffer from soft-story mechanism. This damage mode results in poor ductility and limited energy dissipation. Continuous components offer alternatives that may avoid such failures. A novel infilled rocking wall frame system is proposed that takes advantage of continuous component and rocking characteristics. Previous studies have investigated similar systems that combine a reinforced concrete frame and a wall with rocking behavior used. However, a large-scale experimental study of a reinforced concrete frame combined with a rocking wall has not been reported. In this study, a seismic performance evaluation of the newly proposed infilled rocking wall frame structure was conducted through quasi-static cyclic testing. Critical joints were designed and verified. Numerical models were established and calibrated to estimate frame shear forces. The results evaluation demonstrate that an infilled rocking wall frame can effectively avoid soft-story mechanisms. Capacity and initial stiffness are greatly improved and self-centering behavior is achieved with the help of the infilled rocking wall. Drift distribution becomes more uniform with height. Concrete cracks and damage occurs in desired areas. The infilled rocking wall frame offers a promising approach to achieving seismic resilience.

  18. Interactions of Condensed Tannins with Saccharomyces cerevisiae Yeast Cells and Cell Walls: Tannin Location by Microscopy.

    Science.gov (United States)

    Mekoue Nguela, Julie; Vernhet, Aude; Sieczkowski, Nathalie; Brillouet, Jean-Marc

    2015-09-02

    Interactions between grape tannins/red wine polyphenols and yeast cells/cell walls was previously studied within the framework of red wine aging and the use of yeast-derived products as an alternative to aging on lees. Results evidenced a quite different behavior between whole cells (biomass grown to elaborate yeast-derived products, inactivated yeast, and yeast inactivated after autolysis) and yeast cell walls (obtained from mechanical disruption of the biomass). Briefly, whole cells exhibited a high capacity to irreversibly adsorb grape and wine tannins, whereas only weak interactions were observed for cell walls. This last point was quite unexpected considering the literature and called into question the real role of cell walls in yeasts' ability to fix tannins. In the present work, tannin location after interactions between grape and wine tannins and yeast cells and cell walls was studied by means of transmission electron microscopy, light epifluorescence, and confocal microscopy. Microscopy observations evidenced that if tannins interact with cell walls, and especially cell wall mannoproteins, they also diffuse freely through the walls of dead cells to interact with their plasma membrane and cytoplasmic components.

  19. Wall-based identification of coherent structures in wall-bounded turbulence

    Science.gov (United States)

    Sanmiguel Vila, C.; Flores, O.

    2018-04-01

    During the last decades, a number of reduced order models based on coherent structures have been proposed to describe wall-bounded turbulence. Many of these models emphasize the importance of coherent wall-normal velocity eddies (ν-eddies), which drive the generation of the very long streamwise velocity structures observed in the logarithmic and outer region. In order to use these models to improve our ability to control wall-bounded turbulence in realistic applications, these ν-eddies need to be identified from the wall in a non-intrusive way. In this paper, the possibility of using the pressure signal at the wall to identify these ν-eddies is explored, analyzing the cross-correlation between the wall-normal velocity component and the pressure fluctuations at the wall in a DNS of a turbulent channel flow at Reτ = 939. The results show that the cross-correlation has a region of negative correlation upstream, and a region of positive correlation backwards. In the spanwise direction the correlation decays monotonously, except very close to the wall where a change of sign of the correlation coefficient is observed. Moreover, filtering the pressure fluctuations at the wall in space results in an increase of the region where the cross-correlation is strong, both for the positively and the negatively correlated regions. The use of a time filter for the pressure fluctuations at the wall yields different results, displacing the regions of strong correlation without changing much their sizes. The results suggest that space-filtering the pressure at the wall is a feasible way to identify ν-eddies of different sizes, which could be used to trigger turbulent control strategies.

  20. Conceptual Design and Feasibility Analyses of a Robotic System for Automated Exterior Wall Painting

    Directory of Open Access Journals (Sweden)

    Young S. Kim

    2008-11-01

    Full Text Available There are approximately 6,677,000 apartment housing units in South Korea. Exterior wall painting for such multi-dwelling apartment housings in South Korea represents a typical area to which construction automation technology can be applied for improvement in safety, productivity, quality, and cost over the conventional method. The conventional exterior wall painting is costly and labor-intensive, and it especially exposes workers to significant health and safety risks. The primary objective of this study is to design a conceptual model of an exterior wall painting robot which is applicable to apartment housing construction and maintenance, and to conduct its technical?economical feasibility analyses. In this study, a design concept using a high ladder truck is proposed as the best alternative for automation of the exterior wall painting. Conclusions made in this study show that the proposed exterior wall painting robot is technically and economically feasible, and can greatly enhance safety, productivity, and quality compared to the conventional method. Finally, it is expected that the conceptual model of the exterior wall painting robot would be efficiently used in various applications in exterior wall finishing and maintenance of other architectural and civil structures such as commercial buildings, towers, and high-rise storage tanks.

  1. Cell wall mannoprotein of Candida albicans induces cell cycle alternation and inhibits apoptosis of HaCaT cells via NF-κB signal pathway.

    Science.gov (United States)

    Han, Yang; Jiang, Hang-Hang; Zhang, Yu-Jing; Hao, Xing-Jia; Sun, Yu-Zhe; Qi, Rui-Qun; Chen, Hong-Duo; Gao, Xing-Hua

    2017-10-01

    Candida albicans (C. albicans) is a commensal organism in human and a well-known dimorphic opportunistic pathogenic fungus. Though plenty of researches on the pathogenesis of C. albicans have been performed, the mechanism is not fully understood. The cell wall components of C. albicans have been documented to play important roles in its pathogenic processes. To further study the infectious mechanism of C. albicans, we investigated the potential functional role of its cell wall mannoprotein in cell cycle and apoptosis of HaCaT cells. We found that mannoprotein could promote the transition of cell cycle from G1/G0 to S phase, in which Cyclin D1, CDK4 and p-Rb, the major regulators of the cell cycle progression, showed significant upregulation, and CDKN1A (cyclin dependent kinase inhibitor 1A (p21)) showed significant downregulation. Mannoprotein also could inhibit apoptosis of HaCaT cells, which was well associated with increased expression of BCL2 (Bcl-2). Moreover, mannoprotein could increase the phosphorylation levels of RELA (p65) and NFKBIA (IκBα), as the key factors of NF-κB signal pathway in HaCaT cells, suggesting the activation of NF-κB signal pathway. Additionally, a NF-κB specific inhibitor, PDTC, could rescue the effect of mannoprotein on cell cycle and apoptosis of HaCaT cells, which suggested that mannoprotein could activate NF-κB signal pathway to mediate cell cycle alternation and inhibit apoptosis. Copyright © 2017. Published by Elsevier Ltd.

  2. Rotational motion in nuclei

    International Nuclear Information System (INIS)

    Bohr, A.

    1976-01-01

    Nuclear structure theories are reviewed concerned with nuclei rotational motion. The development of the deformed nucleus model facilitated a discovery of rotational spectra of nuclei. Comprehensive verification of the rotational scheme and a successful classification of corresponding spectra stimulated investigations of the rotational movement dynamics. Values of nuclear moments of inertia proved to fall between two marginal values corresponding to rotation of a solid and hydrodynamic pattern of an unrotating flow, respectively. The discovery of governing role of the deformation and a degree of a symmetry violence for determining rotational degrees of freedon is pointed out to pave the way for generalization of the rotational spectra

  3. Internal Flow of Contra-Rotating Small Hydroturbine at Off- Design Flow Rates

    Science.gov (United States)

    SHIGEMITSU, Toru; TAKESHIMA, Yasutoshi; OGAWA, Yuya; FUKUTOMI, Junichiro

    2016-11-01

    Small hydropower generation is one of important alternative energy, and enormous potential lie in the small hydropower. However, efficiency of small hydroturbines is lower than that of large one. Then, there are demands for small hydroturbines to keep high performance in wide flow rate range. Therefore, we adopted contra-rotating rotors, which can be expected to achieve high performance. In this research, performance of the contra-rotating small hydroturbine with 60mm casing diameter was investigated by an experiment and numerical analysis. Efficiency of the contra-rotating small hydroturbine was high in pico-hydroturbine and high efficiency could be kept in wide flow rate range, however the performance of a rear rotor decreased significantly in partial flow rates. Then, internal flow condition, which was difficult to measure experimentally, was investigated by the numerical flow analysis. Then, a relation between the performance and internal flow condition was considered by the numerical analysis result.

  4. Adiabatic rotation, quantum search, and preparation of superposition states

    International Nuclear Information System (INIS)

    Siu, M. Stewart

    2007-01-01

    We introduce the idea of using adiabatic rotation to generate superpositions of a large class of quantum states. For quantum computing this is an interesting alternative to the well-studied 'straight line' adiabatic evolution. In ways that complement recent results, we show how to efficiently prepare three types of states: Kitaev's toric code state, the cluster state of the measurement-based computation model, and the history state used in the adiabatic simulation of a quantum circuit. We also show that the method, when adapted for quantum search, provides quadratic speedup as other optimal methods do with the advantages that the problem Hamiltonian is time independent and that the energy gap above the ground state is strictly nondecreasing with time. Likewise the method can be used for optimization as an alternative to the standard adiabatic algorithm

  5. Nuclear reactor assembly

    International Nuclear Information System (INIS)

    Dorner, H.; Scholz, M.; Jungmann, A.

    1975-01-01

    A nuclear reactor assembly includes a reactor pressure tank having a substantially cylindrical side wall surrounded by the wall of a cylindrical cavity formed by a biological shield. A rotative cylindrical wall is interposed between the walls and has means for rotating it from outside of the shield, and a probe is carried by the rotative wall for monitoring the pressure tank's wall. The probe is vertically movable relative to the rotative cylindrical wall, so that by the probe's vertical movement and rotation of the rotative cylinder, the reactor's wall can be very extensively monitored. If the reactor pressure tank's wall fails, it is contained by the rotative wall which is backed-up by the shield cavity wall. (Official Gazette)

  6. Uncooled EGR as a means of limiting wall-wetting under early direct injection conditions

    NARCIS (Netherlands)

    Boot, M.D.; Luijten, C.C.M.; Somers, L.M.T.; Eguz, U.; Erp, D.D.T.M. van; Albrecht, A.; Baert, R.S.G.

    2009-01-01

    Collision of injected fuel spray against the cylinder liner (wall-wetting) is one of the main hurdles that must be overcome in order for early direct injection Premixed Charge Compression Ignition (EDI PCCI) combustion to become a viable alternative for conventional DI diesel combustion. Preferably,

  7. Model Solutions for Performance-Based Seismic Analysis of an Anchored Sheet Pile Quay Wall

    NARCIS (Netherlands)

    Habets, C.J.W.; Peters, D.J.; de Gijt, J.G.; Metrikine, A.; Jonkman, S.N.

    2016-01-01

    Conventional seismic designs of quay walls in ports are mostly based on pseudo-static analysis. A more advanced alternative is the Performance-Based Design (PBD) method, which evaluates permanent deformations and amounts of (repairable) damage under seismic loading. The aim of this study is to

  8. Surface dimpling on rotating work piece using rotation cutting tool

    Science.gov (United States)

    Bhapkar, Rohit Arun; Larsen, Eric Richard

    2015-03-31

    A combined method of machining and applying a surface texture to a work piece and a tool assembly that is capable of machining and applying a surface texture to a work piece are disclosed. The disclosed method includes machining portions of an outer or inner surface of a work piece. The method also includes rotating the work piece in front of a rotating cutting tool and engaging the outer surface of the work piece with the rotating cutting tool to cut dimples in the outer surface of the work piece. The disclosed tool assembly includes a rotating cutting tool coupled to an end of a rotational machining device, such as a lathe. The same tool assembly can be used to both machine the work piece and apply a surface texture to the work piece without unloading the work piece from the tool assembly.

  9. Ambiguous walls

    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...

  10. Magnetostrictive energy generator for harvesting the rotation of human knee joint

    Directory of Open Access Journals (Sweden)

    Baiping Yan

    2018-05-01

    Full Text Available This paper presents the design and fabrication of a rotary-impact magnetostrictive energy generator, used to harvest the rotation of human knee joint. The harvester consists of twelve movable Terfenol-D rods, surrounded by the picked up coils respectively, and alternate permanent magnet (PM array sandwiched in each part of the shell. Rotational electromagnetic power generating effect and impacted magnetostrictive power generating effect are designed in the harvester. Modeling and simulation are used to validate the concept. Then, magnetic field and leakage of the harvester are analyzed, electromagnetic force in the harvester is simulated. A prototype of harvester is fabricated, and subjected to the experimental characterization. It can be concluded that huge induced voltage generated in the short-time impact situation and that induced voltage in the harvester can reach up to 60-80 volts at 0.91Hz low frequency rotation. Also, the presented harvester has good harvesting effects at low frequency human walking and periodic swing crus situation, which are suitable to be used for future researches of wearable knee joint applications.

  11. Polarization digital holographic microscopy using low-cost liquid crystal polarization rotators

    Science.gov (United States)

    Dovhaliuk, Rostyslav Yu

    2018-02-01

    Polarization imaging methods are actively used to study anisotropic objects. A number of methods and systems, such as imaging polarimeters, were proposed to measure the state of polarization of light that passed through the object. Digital holographic and interferometric approaches can be used to quantitatively measure both amplitude and phase of a wavefront. Using polarization modulation optics, the measurement capabilities of such interference-based systems can be extended to measure polarization-dependent parameters, such as phase retardation. Different kinds of polarization rotators can be used to alternate the polarization of a reference beam. Liquid crystals are used in a rapidly increasing number of different optoelectronic devices. Twisted nematic liquid crystals are widely used as amplitude modulators in electronic displays and light valves or shutter glass. Such devices are of particular interest for polarization imaging, as they can be used as polarization rotators, and due to large-scale manufacturing have relatively low cost. A simple Mach-Zehnder polarized holographic setup that uses modified shutter glass as a polarization rotator is demonstrated. The suggested approach is experimentally validated by measuring retardation of quarter-wave film.

  12. Magnetostrictive energy generator for harvesting the rotation of human knee joint

    Science.gov (United States)

    Yan, Baiping; Zhang, Chengming; Li, Liyi

    2018-05-01

    This paper presents the design and fabrication of a rotary-impact magnetostrictive energy generator, used to harvest the rotation of human knee joint. The harvester consists of twelve movable Terfenol-D rods, surrounded by the picked up coils respectively, and alternate permanent magnet (PM) array sandwiched in each part of the shell. Rotational electromagnetic power generating effect and impacted magnetostrictive power generating effect are designed in the harvester. Modeling and simulation are used to validate the concept. Then, magnetic field and leakage of the harvester are analyzed, electromagnetic force in the harvester is simulated. A prototype of harvester is fabricated, and subjected to the experimental characterization. It can be concluded that huge induced voltage generated in the short-time impact situation and that induced voltage in the harvester can reach up to 60-80 volts at 0.91Hz low frequency rotation. Also, the presented harvester has good harvesting effects at low frequency human walking and periodic swing crus situation, which are suitable to be used for future researches of wearable knee joint applications.

  13. Simultaneous rotational and vibrational CARS generation through a multiple-frequency combination technique

    International Nuclear Information System (INIS)

    Alden, M.; Bengtsson, P.E.; Edner, H.

    1987-01-01

    One most promising laser technique for probing combustion processes is coherent anti-Stokes Raman scattering (CARS), which due to its coherent nature and signal strength is applied in several real-world applications. Until today almost all CARS experiments are based on probing the population of molecular vibrational energy levels. However, there are several reasons rotational CARS, i.e. probing of rotational energy levels, may provide a complement to or even a better choice than vibrational CARS. Recently an alternative way to produce rotational CARS spectra is proposed, which is based on a multiple-frequency combination technique. The energy-level diagram for this process is presented. Two dye laser beams at ω/sub r/, and one fix frequency laser beam at ω/sub g/ are employed. ω/sub r,1/ and ω/sub r,2/ are two frequencies of many possible pairs with a frequency difference matching a rotational transition in a molecule. The excitation induced by ω/sub r,1/ and ω/sub r,2/ is then scattered by the narrowband ω/sub g/ beam resulting in a CARS beam ω/sub g/ at ω/sub g/ + ω/sub r,1/ - ω/sub r,2/. An interesting feature with this technique is that it is possible to generate simultaneously a rotational and vibrational CARS spectrum by using a double-folded boxcars phase matching approach. The authors believe that the proposed technique for producing rotational and vibration CARS spectra could be of interest, e.g., when measuring in highly turbulent flows. In this case the rotational CARS spectra could use for temperature measurements in the cooler parts, whereas vibrational CARS are to be preferred when measuring in the hotter parts

  14. 'Eco-house 99' - Full-scale demonstration of solar walls with building integrated heat storages

    Energy Technology Data Exchange (ETDEWEB)

    Hummelshoej, R.M.; Rahbek, J.E. [COWI Consulting Engineers and Planners AS (Denmark)

    2000-07-01

    A critical issue for solar systems in northern latitudes is the economic profitability. It is often said that the techniques for solar utilisation are expensive and unprofitable. This is, however, not always the case. A new project with 59 low energy terrace houses was carried out in Kolding, Denmark. The houses are designed as ecological buildings with emphasis on total economy based on low operation and maintenance costs, energy conservation and passive/hybrid solar utilisation. Besides direct solar gain through windows, each house has a solar wall of 6-8.5 m{sup 2} on the south facade. The solar walls are used both for heating of ventilation air and for space heating. The solar walls deliver heat to the dwellings during the heating season. To optimise the energy utilisation from the solar walls, the energy is stored internally in building integrated heat storages. Two different new types of prefabricated heat storages are built into the houses. One is an internal concrete wall with embedded ventilation pipes, and the other is a hollow concrete element with integrated stone bed. The heat storages are mainly designed to store solar energy from the day to the evening and the night. Because the solar walls and the heat storages have been a part of the design process from the start, the additional expenses are as low as 30-140 Euro/m{sup 2} solar wall compared with the alternative facade. This is far less than what it costs to add a solar wall on an existing building. Measurements over one year show that the yield of the solar walls is in the range of 115-125 kWh/m{sup 2}/year as expected. With the actual financing, the annual payment of the additional expenses for the solar systems is between 1-6 Euro/m{sup 2} solar wall, while the annual savings are about 5 Euro/year/m{sup 2} (with an energy price of 0.042 Euro/kWh). Dependent on which alternative facade construction the solar wall system is compared with, the profit of the system is in the range of 1 to +4 Euro

  15. Numerical simulations of thermal convection in a rotating spherical fluid shell at high Taylor and Rayleigh numbers

    International Nuclear Information System (INIS)

    Sun, Z.; Schubert, G.

    1995-01-01

    In this study, we carry out numerical simulations of thermal convection in a rapidly rotating spherical fluid shell at high Taylor number Ta and Rayleigh number R with a nonlinear, three-dimensional, time-dependent, spectral-transform code. The parameters used in the simulations are chosen to be in a range which allows us to study two different types of convection, i.e., single column and multi-layered types, and the transition between them. Numerical solutions feature highly time-dependent north--south open columnar convective cells. The cells occur irregularly in longitude, are quasi-layered in cylindrical radius, and maintain alternating bands of mean zonal flow. The complex convective structure and the banded mean zonal flow are results of the high Taylor and Rayleigh numbers. The transition between the two types of convection appears to occur gradually with increasing Rayleigh and Taylor numbers. At a Taylor number of 10 7 the differential rotation pattern consists of an inner cylindrical region of subrotation and an outer cylindrical shell of superrotation manifest at the outer boundary as an equatorial superrotation and a high latitude subrotation. The differential rotation pattern is similar at Ta=10 8 and low Rayleigh number. Cylindrical shells of alternately directed mean zonal flow begin to develop at Ta=10 8 and R=50R c and at Ta=10 9 and R=25R c . This pattern is seen on the outer surface as a latitudinally-banded zonal flow consisting of an equatorial superrotation, a middle and high latitude subrotation, and a polar superrotation. At Ta=10 9 and R=50R c the differential rotation appears at the surface as a broad eastward flow in the equatorial region with alternating bands of westward and eastward flow at high latitudes. copyright 1995 American Institute of Physics

  16. Large eddy simulation of rotating turbulent flows and heat transfer by the lattice Boltzmann method

    Science.gov (United States)

    Liou, Tong-Miin; Wang, Chun-Sheng

    2018-01-01

    Due to its advantage in parallel efficiency and wall treatment over conventional Navier-Stokes equation-based methods, the lattice Boltzmann method (LBM) has emerged as an efficient tool in simulating turbulent heat and fluid flows. To properly simulate the rotating turbulent flow and heat transfer, which plays a pivotal role in tremendous engineering devices such as gas turbines, wind turbines, centrifugal compressors, and rotary machines, the lattice Boltzmann equations must be reformulated in a rotating coordinate. In this study, a single-rotating reference frame (SRF) formulation of the Boltzmann equations is newly proposed combined with a subgrid scale model for the large eddy simulation of rotating turbulent flows and heat transfer. The subgrid scale closure is modeled by a shear-improved Smagorinsky model. Since the strain rates are also locally determined by the non-equilibrium part of the distribution function, the calculation process is entirely local. The pressure-driven turbulent channel flow with spanwise rotation and heat transfer is used for validating the approach. The Reynolds number characterized by the friction velocity and channel half height is fixed at 194, whereas the rotation number in terms of the friction velocity and channel height ranges from 0 to 3.0. A working fluid of air is chosen, which corresponds to a Prandtl number of 0.71. Calculated results are demonstrated in terms of mean velocity, Reynolds stress, root mean square (RMS) velocity fluctuations, mean temperature, RMS temperature fluctuations, and turbulent heat flux. Good agreement is found between the present LBM predictions and previous direct numerical simulation data obtained by solving the conventional Navier-Stokes equations, which confirms the capability of the proposed SRF LBM and subgrid scale relaxation time formulation for the computation of rotating turbulent flows and heat transfer.

  17. The rotating universe

    International Nuclear Information System (INIS)

    Ruben, G.; Treder, H.J.

    1987-01-01

    For a long time the question whether the universe rotates or not is discussed. Aspects of Huygens, Newton, Mach and other important historical scientists in this field are reported. The investigations of the mathematician Kurt Groedel in order to prove the rotation of the universe are illustrated. Kurt Groedel has shown that Einstein's gravitational equations of general relativity theory and the cosmological postulate of global homogeneity of cosmic matter (that is the Copernical principle) are not contradictionary to a rotating universe. Abberation measurements, position determination by means of radiointerferometry and methods for the determination of the rotation of the universe from the isotropy of the background radiation are presented. From these experiments it can be concluded that the universe seems not to rotate as already Einstein expected

  18. Rotation sensor switch

    International Nuclear Information System (INIS)

    Sevec, J.B.

    1978-01-01

    A protective device to provide a warning if a piece of rotating machinery slows or stops is comprised of a pair of hinged weights disposed to rotate on a rotating shaft of the equipment. When the equipment is rotating, the weights remain in a plane essentially perpendicular to the shaft and constitute part of an electrical circuit that is open. When the shaft slows or stops, the weights are attracted to a pair of concentric electrically conducting disks disposed in a plane perpendicular to the shaft and parallel to the plane of the weights when rotating. A disk magnet attracts the weights to the electrically conducting plates and maintains the electrical contact at the plates to complete an electrical circuit that can then provide an alarm signal

  19. Steady-state configurations of Dzyaloshinskii domain walls driven by field and current

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Tejerina, L., E-mail: luis.st@ee.uva.es [Departamento de Electricidad y Electrónica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid (Spain); Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Salamanca, 37011 Salamanca (Spain); Alejos, O. [Departamento de Electricidad y Electrónica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid (Spain); Martínez, E. [Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Salamanca, 37011 Salamanca (Spain)

    2017-02-01

    The dynamics of Dzyaloshinskii domain walls (DDW) in ultrathin ferromagnetic strips with perpendicular magnetic anisotropy, for different values of both perpendicular field and longitudinal current excitation associated to the Spin-Hall effect, has been studied, taking into account different values of the interfacial Dzyaloshinskii-Moriya interaction (DMI). This study has been carried out with the help of the q-Φ one-dimensional model and micromagnetic simulations. We have found that Walker breakdown may be avoided by applying a certain threshold current, even though the inverse effect is also possible. We have also found that, for particular values of field and current, the magnetization within the DDW experiences an abrupt change of orientation, which provokes a change on the contribution of current to the terminal DDW velocity. This effect disappears for sufficiently strong DMI, as it is expected from the model. - Highlights: • Steady-state configurations of Dzyaloshinskii domain walls driven by field and current have been reported. • Field-like torques and Slonczewskii-like torques due to spin-orbit interactions have been considered. • The response is associated with the rotation of the domain wall inner magnetization. • An asymmetric behavior arising from the existence of degenerate states is shown. • The asymmetry results in different travelled distances and/or terminal speeds.

  20. Steady-state configurations of Dzyaloshinskii domain walls driven by field and current

    International Nuclear Information System (INIS)

    Sánchez-Tejerina, L.; Alejos, O.; Martínez, E.

    2017-01-01

    The dynamics of Dzyaloshinskii domain walls (DDW) in ultrathin ferromagnetic strips with perpendicular magnetic anisotropy, for different values of both perpendicular field and longitudinal current excitation associated to the Spin-Hall effect, has been studied, taking into account different values of the interfacial Dzyaloshinskii-Moriya interaction (DMI). This study has been carried out with the help of the q-Φ one-dimensional model and micromagnetic simulations. We have found that Walker breakdown may be avoided by applying a certain threshold current, even though the inverse effect is also possible. We have also found that, for particular values of field and current, the magnetization within the DDW experiences an abrupt change of orientation, which provokes a change on the contribution of current to the terminal DDW velocity. This effect disappears for sufficiently strong DMI, as it is expected from the model. - Highlights: • Steady-state configurations of Dzyaloshinskii domain walls driven by field and current have been reported. • Field-like torques and Slonczewskii-like torques due to spin-orbit interactions have been considered. • The response is associated with the rotation of the domain wall inner magnetization. • An asymmetric behavior arising from the existence of degenerate states is shown. • The asymmetry results in different travelled distances and/or terminal speeds.

  1. High-R Walls for Remodeling: Wall Cavity Moisture Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Wiehagen, J.; Kochkin, V.

    2012-12-01

    The focus of the study is on the performance of wall systems, and in particular, the moisture characteristics inside the wall cavity and in the wood sheathing. Furthermore, while this research will initially address new home construction, the goal is to address potential moisture issues in wall cavities of existing homes when insulation and air sealing improvements are made.

  2. High-R Walls for Remodeling. Wall Cavity Moisture Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Wiehagen, J. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Kochkin, V. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States)

    2012-12-01

    The focus of the study is on the performance of wall systems, and in particular, the moisture characteristics inside the wall cavity and in the wood sheathing. Furthermore, while this research will initially address new home construction, the goal is to address potential moisture issues in wall cavities of existing homes when insulation and air sealing improvements are made.

  3. Alternating-current ohmic heating in a helical stellarator

    International Nuclear Information System (INIS)

    Funato, Yasuyuki; Kitajima, Sumio; Watanabe, Hiroshige

    1984-01-01

    A toroidal plasma is generated successively by an alternating-current discharge in a helical or non-planar torus, and is confined quasi-stationarily by a longitudinal magnetic field with a high rotational transform angle. The particle confinement time obtained experimentally is estimated to be 3-10 ms, which is compared with theoretical values for this system, and is much larger than the time of pulse interval of the plasma production. (author)

  4. Effects of fluid flow on heat transfer in large rotating electrical machines

    International Nuclear Information System (INIS)

    Lancial, Nicolas

    2014-01-01

    EDF operates a large number of electrical rotating machines in its electricity generation capacity. Thermal stresses which affect them can cause local heating, sufficient to damage their integrity. The present work contributes to provide methodologies for detecting hot spots in these machines, better understanding the topology of rotating flows and identifying their effects on heat transfer. Several experimental scale model were used by increasing their complexity to understand and validate the numerical simulations. A first study on a turbulent wall jet over a non-confined backward-facing step (half-pole hydro-generator) notes significant differences compared to results from confined case: both of them are present in an hydro-generator. A second study was done on a small confined rotating scale model to determinate the effects of a Taylor-Couette-Poiseuille on temperature distribution and position of hot spots on the heated rotor, by studying the overall flow regimes flow. These studies have helped to obtain a reliable method based on conjugate heat transfer (CHT) simulations. Another method, based on FEM coupled with the use of an inverse method, has been studied on a large model of hydraulic generator so as to solve the computation time issue of the first methodology. It numerically calculates the convective heat transfer from temperature measurements, but depends on the availability of experimental data. This work has also developed new no-contact measurement techniques as the use of a high-frequency pyrometer which can be applied on rotating machines for monitoring temperature. (author)

  5. Liquid Wall Chambers

    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.

  6. Couple stress fluid flow in a rotating channel with peristalsis

    Science.gov (United States)

    Abd elmaboud, Y.; Abdelsalam, Sara I.; Mekheimer, Kh. S.

    2018-04-01

    This article describes a new model for obtaining closed-form semi-analytical solutions of peristaltic flow induced by sinusoidal wave trains propagating with constant speed on the walls of a two-dimensional rotating infinite channel. The channel rotates with a constant angular speed about the z - axis and is filled with couple stress fluid. The governing equations of the channel deformation and the flow rate inside the channel are derived using the lubrication theory approach. The resulting equations are solved, using the homotopy perturbation method (HPM), for exact solutions to the longitudinal velocity distribution, pressure gradient, flow rate due to secondary velocity, and pressure rise per wavelength. The effect of various values of physical parameters, such as, Taylor's number and couple stress parameter, together with some interesting features of peristaltic flow are discussed through graphs. The trapping phenomenon is investigated for different values of parameters under consideration. It is shown that Taylor's number and the couple stress parameter have an increasing effect on the longitudinal velocity distribution till half of the channel, on the flow rate due to secondary velocity, and on the number of closed streamlines circulating the bolus.

  7. Passivity-Based Control of Rotational and Translational Timoshenko Arms

    Directory of Open Access Journals (Sweden)

    Minoru Sasaki

    2012-01-01

    Full Text Available It is shown that the alternate passivity-based control schemes can be designed which explicitly exploit the passivity properties of the Timoshenko model. This approach has the advantage over the conventional methods in the respect that it allows one to deal directly with the system's partial differential equations without resorting to approximations. Numerical results for the tracking control of a translational and rotational flexible Timoshenko arm are presented and compared. They verify that the proposed control schemes are effective at controlling flexible dynamical systems.

  8. A low-background piston-cylinder type hybrid high pressure cell for muon-spin rotation/relaxation experiments

    OpenAIRE

    Shermadini, Z.; Khasanov, R.; Elender, M.; Simutis, G.; Guguchia, Z.; Kamenev, K. V.; Amato, A.

    2017-01-01

    A low background double-wall piston-cylinder-type pressure cell is developed at the Paul Scherrer Institute. The cell is made from BERLYCO-25 (beryllium copper) and MP35N nonmagnetic alloys with the design and dimensions which are specifically adapted to muon-spin rotation/relaxation (muSR) measurements. The mechanical design and performance of the pressure cell are evaluated using finite-element analysis (FEA). By including the measured stress-strain characteristics of the material into the ...

  9. Simulation of the development and interaction of instabilities in a relativistic electron beam under variation of the beam wall thickness

    Energy Technology Data Exchange (ETDEWEB)

    Badarin, A. A.; Kurkin, S. A. [Saratov State University (Russian Federation); Koronovskii, A. A. [Yuri Gagarin State Technical University (Russian Federation); Rak, A. O. [Belorussian State University of Informatics and Radioelectronics (Belarus); Hramov, A. E., E-mail: hramovae@gmail.com [Saratov State University (Russian Federation)

    2017-03-15

    The development and interaction of Bursian and diocotron instabilities in an annular relativistic electron beam propagating in a cylindrical drift chamber are investigated analytically and numerically as functions of the beam wall thickness and the magnitude of the external uniform magnetic field. It is found that the interaction of instabilities results in the formation of a virtual cathode with a complicated rotating helical structure and several reflection regions (electron bunches) in the azimuthal direction. It is shown that the number of electron bunches in the azimuthal direction increases with decreasing beam wall thickness and depends in a complicated manner on the magnitude of the external magnetic field.

  10. Rotationally invariant correlation filtering

    International Nuclear Information System (INIS)

    Schils, G.F.; Sweeney, D.W.

    1985-01-01

    A method is presented for analyzing and designing optical correlation filters that have tailored rotational invariance properties. The concept of a correlation of an image with a rotation of itself is introduced. A unified theory of rotation-invariant filtering is then formulated. The unified approach describes matched filters (with no rotation invariance) and circular-harmonic filters (with full rotation invariance) as special cases. The continuum of intermediate cases is described in terms of a cyclic convolution operation over angle. The angular filtering approach allows an exact choice for the continuous trade-off between loss of the correlation energy (or specificity regarding the image) and the amount of rotational invariance desired

  11. Rising damp in building walls: the wall base ventilation system

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, A.S.; Delgado, J.M.P.Q.; Freitas, V.P. de [Faculdade de Engenharia da Universidade do Porto, Laboratorio de Fisica das Construcoes (LFC), Departamento de Engenharia Civil, Porto (Portugal)

    2012-12-15

    This work intends to validate a new system for treating rising damp in historic buildings walls. The results of laboratory experiments show that an efficient way of treating rising damp is by ventilating the wall base, using the HUMIVENT technique. The analytical model presented describes very well the observed features of rising damp in walls, verified by laboratory tests, who contributed for a simple sizing of the wall base ventilation system that will be implemented in historic buildings. (orig.)

  12. Quantum Interference Control of Ballistic Magneto- resistance in a Magnetic Nanowire Containing Two Atomic- Size Domain Walls

    Directory of Open Access Journals (Sweden)

    V. Fallahi

    2012-06-01

    Full Text Available The magnetoresistance of a one-dimensional electron gas in a metallic ferromagnetic nanowire containing two atomic-size domain walls has been investigated in the presence of spin-orbit interaction. The magnetoresistance is calculated in the ballistic regime, within the Landauer-Büttiker formalism. It has been demonstrated that the conductance of a magnetic nanowire with double domain walls can be controlled through the domain walls separation. Also, we have represented another alternative way that enables us to handle easily the magnetoresistance of such a system as well as its conductance by utilizing the Rashba-type spin-orbit interaction induced by the external gates.

  13. Field-induced structures and rheology of a magnetorheological suspension confined between two walls

    International Nuclear Information System (INIS)

    Carletto, P; Bossis, G

    2003-01-01

    We have determined experimentally the parameters characterizing the structures formed in a magnetic colloidal suspension subjected to a unidirectional magnetic field and a rotating field for different cell thicknesses. In this latter case one observes the formation of a periodic structure in parallel sheets situated in the plane of rotation of the field. A theoretical model based on minimization of the energy allows one to find quantitatively the observations obtained in a unidirectional field. On the other hand, in a rotating field, the agreement is quantitative only if we take the surface energy as an adjustable parameter. We explain this fact on the basis of the existence of a substructure made of discs of particles. In a second part we show the influence of the structures on the rheological properties of the suspension by measuring the shear moduli for different kinds of structure. We find that for the same magnetic field, the shear moduli depend strongly on the structure and can be quite well predicted by a mean field theory; also the critical shear strain is determined and is in agreement with the model. Finally we show that, in a regime with a unidirectional oscillating field without shear flow, a new phenomenon appears if the confining walls are not parallel. In this case we observe the formation of anisotropic aggregates which undergo a collective chaotic rotation around the axis of the aggregates

  14. Vesicles between plasma membrane and cell wall prior to visible senescence of Iris and Dendrobium flowers.

    Science.gov (United States)

    Kamdee, Channatika; Kirasak, Kanjana; Ketsa, Saichol; van Doorn, Wouter G

    2015-09-01

    Cut Iris flowers (Iris x hollandica, cv. Blue Magic) show visible senescence about two days after full opening. Epidermal cells of the outer tepals collapse due to programmed cell death (PCD). Transmission electron microscopy (TEM) showed irregular swelling of the cell walls, starting prior to cell collapse. Compared to cells in flowers that had just opened, wall thickness increased up to tenfold prior to cell death. Fibrils were visible in the swollen walls. After cell death very little of the cell wall remained. Prior to and during visible wall swelling, vesicles (paramural bodies) were observed between the plasma membrane and the cell walls. The vesicles were also found in groups and were accompanied by amorphous substance. They usually showed a single membrane, and had a variety of diameters and electron densities. Cut Dendrobium hybrid cv. Lucky Duan flowers exhibited visible senescence about 14 days after full flower opening. Paramural bodies were also found in Dendrobium tepal epidermis and mesophyll cells, related to wall swelling and degradation. Although alternative explanations are well possible, it is hypothesized that paramural bodies carry enzymes involved in cell wall breakdown. The literature has not yet reported such bodies in association with senescence/PCD. Copyright © 2015 Elsevier GmbH. All rights reserved.

  15. Pediatric resident perceptions of shift work in ward rotations.

    Science.gov (United States)

    Nomura, Osamu; Mishina, Hiroki; Jasti, Harish; Sakai, Hirokazu; Ishiguro, Akira

    2017-10-01

    Although the long working hours of physicians are considered to be a social issue, no effective policies such as duty hour regulations have so far been proposed in Japan. We implemented an overnight call shift (OCS) system for ward rotations to improve the working environment for residents in a pediatric residency program. We later conducted a cross-sectional questionnaire asking the residents to compare this system with the traditional overnight call system. Forty-one pediatric residents participated in this survey. The residents felt that the quality of patient care improved (80.4% agreed). Most felt that there was less emphasis on education (26.8%) and more emphasis on service (31.7%). Overall, the residents reported that the OCS was beneficial (90.2%). In conclusion, the pediatric residents considered the OCS system during ward rotations as beneficial. Alternative solutions are vital to balance improvements in resident work conditions with the requirement for a high quality of education. © 2017 Japan Pediatric Society.

  16. Simultaneous Feedback Control of Plasma Rotation and Stored Energy on the DIII-D Tokamak

    International Nuclear Information System (INIS)

    Scoville, J.T.; Ferron, J.R.; Humphreys, D.A.; Walker, M.L.

    2006-01-01

    One of the major modifications made to the DIII-D tokamak during the 2005 Long Torus Opening was the rotation of one of the four two-source neutral beam injection systems. Prior to this modification, all beams injected power with a component in the same direction as the usual plasma current ('' co-injection ''). Starting in early 2006, two of the seven beams inject with a component in the opposite direction ('' counter-injection ''). This new capability allows, for the first time, a partial decoupling of the injected energy and momentum during neutral beam heating experiments. An immediate advantage of mixed co- and counter-injection beams is the capability to control the plasma rotation velocity. High beta plasmas can now be studied over a wide range of the plasma rotation velocity. The stabilizing effect of rotation on the resistive wall mode (RWM), for example, can be directly compared to the stabilization achieved by external feedback coils. This is an advantage over previous techniques to control plasma rotation, such as magnetic braking, which have had only limited success. We describe development and implementation of a model-based control algorithm for simultaneous regulation of plasma rotation and beta. The model includes the two relevant plasma states (plasma rotation and stored energy), and describes the dynamic effects of the relevant actuators on those states. The actuators include the applied beam torque and beam power, which depend on the amount of co and counter-injected beams. Implementation of the model-based control within the plasma control system (PCS) [B.G. Penaflor, et al, '' Current Status of DIII-D Plasma Control System Computer Upgrades,'' Fusion Eng. and Design 71 (2004) 47] requires real-time measurements of the plasma rotation, obtained from the charge exchange recombination (CER) diagnostic, and stored energy calculated by the real-time EFIT equilibrium reconstruction. Details of this model and its development, and a comparison with

  17. Evaluation of wall thinning profile by flow accelerated corrosion in separation and union pipe

    International Nuclear Information System (INIS)

    Watanabe, Shun; Yoneda, Kimitoshi

    2013-01-01

    Flow Accelerated Corrosion (FAC) is a pipe wall thinning phenomena to be monitored and managed in power plants with high priority. At present, its management has been conducted with conservative evaluation of thinning rate and residual lifetime of the piping based on wall thickness measurements. However, noticeable case of wall thinning was occurred at separation and union pipe. In such pipe system, it is a problem to manage section beneath reinforcing plate of T-tube pipe and 'crotch' of T-joint pipe; the region where wall thickness measurement is difficult to conduct with ordinary ultrasonic testing device. In this study, numerical analysis for separation and union part of T-tube and T-joint pipe was conducted, and wall thinning profile by Flow Accelerated Corrosion was evaluated by calculating mass transfer coefficient and geometry factor. Based on these results, we considered applicable wall thinning management for T-tube and T-joint pipe. In the case of union flow from main and branch pipe, the wall thinning profile of T-tube showed the tendency of increase at main pipe like semielliptical region. On the other hand, noticeable profile appeared at 'crotch' in T-joint. Although it was found that geometry factor of T-joint in this case was half the value of T-tube, an alternative evaluation method to previous one might be needed for the profiles of 'semielliptical region' and 'crotch'. (author)

  18. Reliable 5-min real-time MR technique for left-ventricular-wall motion analysis

    International Nuclear Information System (INIS)

    Katoh, Marcus; Spuentrup, Elmar; Guenther, Rolf W.; Buecker, Arno; Kuehl, Harald P.; Lipke, Claudia S.A.

    2007-01-01

    The aim of this study was to investigate the value of a real-time magnetic resonance imaging (MRI) approach for the assessment of left-ventricular-wall motion in patients with insufficient transthoracic echocardiography in terms of accuracy and temporal expenditure. Twenty-five consecutive patients were examined on a 1.5-Tesla whole-body MR system (ACS-NT, Philips Medical Systems, Best, NL) using a real-time and ECG-gated (the current gold standard) steady-state free-precession (SSFP) sequence. Wall motion was analyzed by three observers by consensus interpretation. In addition, the preparation, scanning, and overall examination times were measured. The assessment of the wall motion demonstrated a close agreement between the two modalities resulting in a mean κ coefficient of 0.8. At the same time, each stage of the examination was significantly shortened using the real-time MR approach. Real-time imaging allows for accurate assessment of left-ventricular-wall motion with the added benefit of decreased examination time. Therefore, it may serve as a cost-efficient alternative in patients with insufficient echocardiography. (orig.)

  19. A study of energy dissipation and critical speed of granular flow in a rotating cylinder

    Science.gov (United States)

    Dragomir, Sergiu C.; Sinnott, Mathew D.; Semercigil, S. Eren; Turan, Özden F.

    2014-12-01

    Tuned vibration absorbers may improve the safety of flexible structures which are prone to excessive oscillation magnitudes under dynamic loads. A novel absorber design proposes sloshing of granular material in a rotating cylinder where the granular material is the energy dissipating agent. As the conventional dissipative elements require maintenance due to the nature of their function, the new design may represent a virtually maintenance free alternative. The angular speed of the cylinder containing particles has a critical centrifuging speed, after which particles remain permanently in contact with the walls and there can be no further dissipation. Until the critical speed, however, dissipation increases proportionally with the angular speed. It is then vital to know the value of the critical speed as the limit of dissipation. The focus of the present study is on determination of the critical centrifuge speed. This critical speed is also of practical importance in bulk-material handling rotary mills, such as dryers and crushers. Experiments and numerical simulations, using Discrete Element Method, are used to determine the critical centrifuging speed. In addition, predictions are given and guidelines are offered for the choice of material properties to maximize the energy dissipation. As a result of a parametric study, the coefficient of friction is found to have the greatest significance on the centrifuging speed.

  20. Rotational explanation of the high-velocity meolecular emission from the Orion Molecular Cloud

    International Nuclear Information System (INIS)

    Clark, F.O.; Biretta, J.A.; Martin, H.M.

    1979-01-01

    The high-velocity molecular emission of the Orion Molecular Cloud has been sampled using the J/sub N/=2 2 --1 1 rotational spectral line of the SO molecule. The resulting profile, including the high-velocity wings, has been reproduced using only known large-scale properties of the gas and applications of the results of published theoretical calculations. No new physical mechanism is required; observed rotation and conservation of angular momentum are sufficient to reproduce the line profile. The resulting physical state appears to be consistent with all known physical properties. This solution is not unique, but indicates the strengths and weaknesses of such a model for interpretation of Orion as well as the similarities of alternative explanations

  1. Lean premixed reacting flows with swirl and wall-separation zones in a contracting chamber

    Science.gov (United States)

    Zhang, Yuxin; Rusak, Zvi; Wang, Shixiao

    2017-11-01

    Low Mach number lean premixed reacting swirling flows with wall-separation zones in a contracting circular finite-length open chamber are studied. Assuming a complete reaction with high activation energy and chemical equilibrium behind the reaction zone, a nonlinear partial differential equation is derived for the solution of the flow stream function behind the reaction zone in terms of the inlet total enthalpy for a reacting flow, specific entropy and the circulation functions. Bifurcation diagrams of steady flows are described as the inlet swirl level is increased at fixed chamber contraction and reaction heat release. The approach is applied to an inlet solid-body rotation flow with constant profiles of the axial velocity, temperature and mixture reactant mass fraction. The computed results provide predictions of the critical inlet swirl levels for the first appearance of wall-separation states and for the size of the separation zone as a function of the inlet swirl ratio, Mach number, chamber contraction and heat release of the reaction. The methodology developed in this paper provides a theoretical feasibility for the development of the technology of swirl-assisted combustion where the reaction zone is supported and stabilized by a wall-separation zone.

  2. Rapidly rotating neutron stars with a massive scalar field—structure and universal relations

    International Nuclear Information System (INIS)

    Doneva, Daniela D.; Yazadjiev, Stoytcho S.

    2016-01-01

    We construct rapidly rotating neutron star models in scalar-tensor theories with a massive scalar field. The fact that the scalar field has nonzero mass leads to very interesting results since the allowed range of values of the coupling parameters is significantly broadened. Deviations from pure general relativity can be very large for values of the parameters that are in agreement with the observations. We found that the rapid rotation can magnify the differences several times compared to the static case. The universal relations between the normalized moment of inertia and quadrupole moment are also investigated both for the slowly and rapidly rotating cases. The results show that these relations are still EOS independent up to a large extend and the deviations from pure general relativity can be large. This places the massive scalar-tensor theories amongst the few alternative theories of gravity that can be tested via the universal I -Love- Q relations.

  3. Rapidly rotating neutron stars with a massive scalar field—structure and universal relations

    Energy Technology Data Exchange (ETDEWEB)

    Doneva, Daniela D.; Yazadjiev, Stoytcho S., E-mail: daniela.doneva@uni-tuebingen.de, E-mail: yazad@phys.uni-sofia.bg [Theoretical Astrophysics, Eberhard Karls University of Tübingen, Tübingen 72076 (Germany)

    2016-11-01

    We construct rapidly rotating neutron star models in scalar-tensor theories with a massive scalar field. The fact that the scalar field has nonzero mass leads to very interesting results since the allowed range of values of the coupling parameters is significantly broadened. Deviations from pure general relativity can be very large for values of the parameters that are in agreement with the observations. We found that the rapid rotation can magnify the differences several times compared to the static case. The universal relations between the normalized moment of inertia and quadrupole moment are also investigated both for the slowly and rapidly rotating cases. The results show that these relations are still EOS independent up to a large extend and the deviations from pure general relativity can be large. This places the massive scalar-tensor theories amongst the few alternative theories of gravity that can be tested via the universal I -Love- Q relations.

  4. NH3 quantum rotators in Hofmann clathrates: intensity and width of rotational transition lines

    International Nuclear Information System (INIS)

    Vorderwisch, Peter; Sobolev, Oleg; Desmedt, Arnaud

    2004-01-01

    Inelastic structure factors for rotational transitions of uniaxial NH 3 quantum rotators, measured in a Hofmann clathrate with biphenyl as guest molecule, agree with those calculated for free rotators. A finite intrinsic line width, found for rotational transitions involving the rotational level j=3 at low temperature, supports a recently suggested model based on resonant rotor-rotor coupling

  5. Rotation Frequencies of Small Jovian Trojan Asteroids: An Excess of Slow Rotators

    Science.gov (United States)

    French, Linda M.; Stephens, Robert D.; James, David J.; Coley, Daniel; Connour, Kyle

    2015-11-01

    Several lines of evidence support a common origin for, and possible hereditary link between, cometary nuclei and jovian Trojan asteroids. Due to their distance and low albedos, few comet-sized Trojans have been studied. We discuss the rotation properties of Jovian Trojan asteroids less than 30 km in diameter. Approximately half the 131 objects discussed here were studied using densely sampled lightcurves (French et al. 2015a, b); Stephens et al. 2015), and the other half were sparse lightcurves obtained by the Palomar Transient Factory (PTF; Waszcazk et al. 2015).A significant fraction (~40%) of the objects in the ground-based sample rotate slowly (P > 24h), with measured periods as long as 375 h (Warner and Stephens 2011). The PTF data show a similar excess of slow rotators. Only 5 objects in the combined data set have rotation periods of less than six hours. Three of these fast rotators were contained in the data set of French et al. these three had a geometric mean rotation period of 5.29 hours. A prolate spheroid held together by gravity rotating with this period would have a critical density of 0.43 gm/cm3, a density similar to that of comets (Lamy et al. 2004).Harris et al. (2012) and Warner et al. (2011) have explored the possible effects on asteroid rotational statistics with the results from wide-field surveys. We will examine Trojan rotation statistics with and without the results from the PTF.

  6. Overview of erosion–deposition diagnostic tools for the ITER-Like Wall in the JET tokamak

    International Nuclear Information System (INIS)

    Rubel, M.; Coad, J.P.; Widdowson, A.; Matthews, G.F.; Esser, H.G.; Hirai, T.; Likonen, J.; Linke, J.; Lungu, C.P.; Mayer, M.; Pedrick, L.; Ruset, C.

    2013-01-01

    This paper presents scientific and technical issues related to the development of erosion–deposition diagnostic tools for JET operated with the ITER-Like Wall: beryllium and tungsten marker tiles and several types of wall probes installed in the main chamber and in the divertor. Markers tiles are the standard limiter and divertor components additionally coated first with a thin sandwich of Ni–Be and Mo–W for, beryllium and tungsten markers, respectively. Both types of markers are embedded in regular arrays of limiter and divertor tiles. Coated W–Be probes are also inserted in the Be-covered Inconel cladding tiles on the central column. Other types of erosion–deposition diagnostic tools are: rotating collectors, deposition traps, louver clips, quartz microbalance and mirrors for the First Mirror Test at JET for ITER. The specific role of these tools is discussed in detail

  7. Pulse Detonation Assessment for Alternative Fuels

    Directory of Open Access Journals (Sweden)

    Muhammad Hanafi Azami

    2017-03-01

    Full Text Available The higher thermodynamic efficiency inherent in a detonation combustion based engine has already led to considerable interest in the development of wave rotor, pulse detonation, and rotating detonation engine configurations as alternative technologies offering improved performance for the next generation of aerospace propulsion systems, but it is now important to consider their emissions also. To assess both performance and emissions, this paper focuses on the feasibility of using alternative fuels in detonation combustion. Thus, the standard aviation fuels Jet-A, Acetylene, Jatropha Bio-synthetic Paraffinic Kerosene, Camelina Bio-synthetic Paraffinic Kerosene, Algal Biofuel, and Microalgae Biofuel are all asessed under detonation combustion conditions. An analytical model accounting for the Rankine-Hugoniot Equation, Rayleigh Line Equation, and Zel’dovich–von Neumann–Doering model, and taking into account single step chemistry and thermophysical properties for a stoichiometric mixture, is applied to a simple detonation tube test case configuration. The computed pressure rise and detonation velocity are shown to be in good agreement with published literature. Additional computations examine the effects of initial pressure, temperature, and mass flux on the physical properties of the flow. The results indicate that alternative fuels require higher initial mass flux and temperature to detonate. The benefits of alternative fuels appear significant.

  8. Stochastic Rotation Dynamics simulations of wetting multi-phase flows

    Science.gov (United States)

    Hiller, Thomas; Sanchez de La Lama, Marta; Brinkmann, Martin

    2016-06-01

    Multi-color Stochastic Rotation Dynamics (SRDmc) has been introduced by Inoue et al. [1,2] as a particle based simulation method to study the flow of emulsion droplets in non-wetting microchannels. In this work, we extend the multi-color method to also account for different wetting conditions. This is achieved by assigning the color information not only to fluid particles but also to virtual wall particles that are required to enforce proper no-slip boundary conditions. To extend the scope of the original SRDmc algorithm to e.g. immiscible two-phase flow with viscosity contrast we implement an angular momentum conserving scheme (SRD+mc). We perform extensive benchmark simulations to show that a mono-phase SRDmc fluid exhibits bulk properties identical to a standard SRD fluid and that SRDmc fluids are applicable to a wide range of immiscible two-phase flows. To quantify the adhesion of a SRD+mc fluid in contact to the walls we measure the apparent contact angle from sessile droplets in mechanical equilibrium. For a further verification of our wettability implementation we compare the dewetting of a liquid film from a wetting stripe to experimental and numerical studies of interfacial morphologies on chemically structured surfaces.

  9. Review of Alternative Management Options of Vegetable Crop Residues to Reduce Nitrate Leaching in Intensive Vegetable Rotations

    Directory of Open Access Journals (Sweden)

    Laura Agneessens

    2014-12-01

    Full Text Available Vegetable crop residues take a particular position relative to arable crops due to often large amounts of biomass with a N content up to 200 kg N ha−1 left behind on the field. An important amount of vegetable crops are harvested during late autumn and despite decreasing soil temperatures during autumn, high rates of N mineralization and nitrification still occur. Vegetable crop residues may lead to considerable N losses through leaching during winter and pose a threat to meeting water quality objectives. However, at the same time vegetable crop residues are a vital link in closing the nutrient and organic matter cycle of soils. Appropriate and sustainable management is needed to harness the full potential of vegetable crop residues. Two fundamentally different crop residue management strategies to reduce N losses during winter in intensive vegetable rotations are reviewed, namely (i on-field management options and modifications to crop rotations and (ii removal of crop residues, followed by a useful and profitable application.

  10. Effects of injection nozzle exit width on rotating detonation engine

    Science.gov (United States)

    Sun, Jian; Zhou, Jin; Liu, Shijie; Lin, Zhiyong; Cai, Jianhua

    2017-11-01

    A series of numerical simulations of RDE modeling real injection nozzles with different exit widths are performed in this paper. The effects of nozzle exit width on chamber inlet state, plenum flowfield and detonation propagation are analyzed. The results are compared with that using an ideal injection model. Although the ideal injection model is a good approximation method to model RDE inlet, the two-dimensional effects of real nozzles are ignored in the ideal injection model so that some complicated phenomena such as the reflected waves caused by the nozzle walls and the reversed flow into the nozzles can not be modeled accurately. Additionally, the ideal injection model overpredicts the block ratio. In all the cases that stabilize at one-wave mode, the block ratio increases as the nozzle exit width gets smaller. The dual-wave mode case also has a relatively high block ratio. A pressure oscillation in the plenum with the same main frequency with the rotating detonation wave is observed. A parameter σ is applied to describe the non-uniformity in the plenum. σ increases as the nozzle exit width gets larger. Under some condition, the heat release on the interface of fresh premixed gas layer and detonation products can be strong enough to induce a new detonation wave. A spontaneous mode-transition process is observed for the smallest exit width case. Due to the detonation products existing in the premixed gas layer before the detonation wave, the detonation wave will propagate through reactants and products alternately, and therefore its strength will vary with time, especially near the chamber inlet. This tendency gets weaker as the injection nozzle exit width increases.

  11. Importance of body rotation during the flight of a butterfly.

    Science.gov (United States)

    Fei, Yueh-Han John; Yang, Jing-Tang

    2016-03-01

    In nature the body motion of a butterfly is clearly observed to involve periodic rotation and varied flight modes. The maneuvers of a butterfly in flight are unique. Based on the flight motion of butterflies (Kallima inachus) recorded in free flight, a numerical model of a butterfly is created to study how its flight relates to body pose; the body motion in a simulation is prescribed and tested with varied initial body angle and rotational amplitude. A butterfly rotates its body to control the direction of the vortex rings generated during flapping flight; the flight modes are found to be closely related to the body motion of a butterfly. When the initial body angle increases, the forward displacement decreases, but the upward displacement increases within a stroke. With increased rotational amplitudes, the jet flows generated by a butterfly eject more downward and further enhance the generation of upward force, according to which a butterfly executes a vertical jump at the end of the downstroke. During this jumping stage, the air relative to the butterfly is moving downward; the butterfly pitches up its body to be parallel to the flow and to decrease the projected area so as to avoid further downward force generated. Our results indicate the importance of the body motion of a butterfly in flight. The inspiration of flight controlled with body motion from the flight of a butterfly might yield an alternative way to control future flight vehicles.

  12. Rotational motion in nuclei

    International Nuclear Information System (INIS)

    Bohr, A.

    1977-01-01

    History is surveyed of the development of the theory of rotational states in nuclei. The situation in the 40's when ideas formed of the collective states of a nucleus is evoked. The general rotation theory and the relation between the single-particle and rotational motion are briefly discussed. Future prospects of the rotation theory development are indicated. (I.W.)

  13. Rotations with Rodrigues' vector

    International Nuclear Information System (INIS)

    Pina, E

    2011-01-01

    The rotational dynamics was studied from the point of view of Rodrigues' vector. This vector is defined here by its connection with other forms of parametrization of the rotation matrix. The rotation matrix was expressed in terms of this vector. The angular velocity was computed using the components of Rodrigues' vector as coordinates. It appears to be a fundamental matrix that is used to express the components of the angular velocity, the rotation matrix and the angular momentum vector. The Hamiltonian formalism of rotational dynamics in terms of this vector uses the same matrix. The quantization of the rotational dynamics is performed with simple rules if one uses Rodrigues' vector and similar formal expressions for the quantum operators that mimic the Hamiltonian classical dynamics.

  14. Effect of rotation on convective mass transfer in rotating channels

    International Nuclear Information System (INIS)

    Pharoah, J.G.; Djilali, N.

    2002-01-01

    Laminar flow and mass transfer in rotating channels is investigated in the context of centrifugal membrane separation. The effect of orientation with respect to the rotational axis is examined for rectangular channels of aspect ratio 3 and the Rossby number is varied from 0.3 to 20.9. Both Ro and the channel orientation are found to have a significant effect on the flow. Mass transfer calculations corresponding to reverse osmosis desalination are carried out at various operating pressures and all rotating cases exhibit significant process enhancements at relatively low rotation rates. Finally, while it is common in the membrane literature to correlate mass transfer performance with membrane shear rates this is shown not to be valid in the cases presented herein. (author)

  15. Ecological sustainability of alternative biomass feedstock production for environmental benefits and bioenergy

    Science.gov (United States)

    Ronald S., Jr. Zalesny; Jill A. Zalesny; Edmund O. Bauer

    2007-01-01

    The incorporation of intensive forestry with waste management fills a much-needed niche throughout numerous phytotechnology applications. There is a growing opportunity to incorporate sustainable recycling of waste waters as irrigation and fertilization for alternative biomass feedstock production systems. However, the success of short rotation woody crops is largely...

  16. FRIST—flipping and rotation invariant sparsifying transform learning and applications

    International Nuclear Information System (INIS)

    Wen, Bihan; Bresler, Yoram; Ravishankar, Saiprasad

    2017-01-01

    Features based on sparse representation, especially using the synthesis dictionary model, have been heavily exploited in signal processing and computer vision. However, synthesis dictionary learning typically involves NP-hard sparse coding and expensive learning steps. Recently, sparsifying transform learning received interest for its cheap computation and its optimal updates in the alternating algorithms. In this work, we develop a methodology for learning flipping and rotation invariant sparsifying transforms, dubbed FRIST, to better represent natural images that contain textures with various geometrical directions. The proposed alternating FRIST learning algorithm involves efficient optimal updates. We provide a convergence guarantee, and demonstrate the empirical convergence behavior of the proposed FRIST learning approach. Preliminary experiments show the promising performance of FRIST learning for sparse image representation, segmentation, denoising, robust inpainting, and compressed sensing-based magnetic resonance image reconstruction. (paper)

  17. Numerical Simulation of Turbulent Fluid Flow and Heat Transfer in a Ribbed Rotating Two-Pass Square Duct

    Directory of Open Access Journals (Sweden)

    Liou Tong-Miin

    2005-01-01

    Full Text Available The local turbulent fluid flow and heat transfer in a rotating two-pass square duct with 19 pairs of in-line 90 ∘ ribs have been investigated computationally. A Reynolds-averaged Navier-Stokes equation (RANS with a two-layer k − ϵ turbulence model was solved. The in-line 90 ∘ ribs were arranged on the leading and trailing walls with rib height-to-hydraulic diameter ratio and pitch-to-height ratio of 0.136 and 10, respectively. The Reynolds number, based on duct hydraulic diameter and bulk mean velocity, was fixed at 1.0 × 10 4 whereas the rotational number varied from 0 to 0.2 . Results are validated with previous measured velocity field and heat transfer coefficient distributions. The validation shows that the effect of rotation on the passage-averaged Nusselt number ratio can be predicted reasonably well; nevertheless, the transverse mean velocity and, in turn, the distribution of regional-averaged Nusselt number ratio are markedly underpredicted in the regions toward which the Coriolis force is directed. Further CFD studies are needed.

  18. High-resolution LES of the rotating stall in a reduced scale model pump-turbine

    International Nuclear Information System (INIS)

    Pacot, Olivier; Avellan, François; Kato, Chisachi

    2014-01-01

    Extending the operating range of modern pump-turbines becomes increasingly important in the course of the integration of renewable energy sources in the existing power grid. However, at partial load condition in pumping mode, the occurrence of rotating stall is critical to the operational safety of the machine and on the grid stability. The understanding of the mechanisms behind this flow phenomenon yet remains vague and incomplete. Past numerical simulations using a RANS approach often led to inconclusive results concerning the physical background. For the first time, the rotating stall is investigated by performing a large scale LES calculation on the HYDRODYNA pump-turbine scale model featuring approximately 100 million elements. The computations were performed on the PRIMEHPC FX10 of the University of Tokyo using the overset Finite Element open source code FrontFlow/blue with the dynamic Smagorinsky turbulence model and the no-slip wall condition. The internal flow computed is the one when operating the pump-turbine at 76% of the best efficiency point in pumping mode, as previous experimental research showed the presence of four rotating cells. The rotating stall phenomenon is accurately reproduced for a reduced Reynolds number using the LES approach with acceptable computing resources. The results show an excellent agreement with available experimental data from the reduced scale model testing at the EPFL Laboratory for Hydraulic Machines. The number of stall cells as well as the propagation speed corroborates the experiment

  19. High-resolution LES of the rotating stall in a reduced scale model pump-turbine

    Science.gov (United States)

    Pacot, Olivier; Kato, Chisachi; Avellan, François

    2014-03-01

    Extending the operating range of modern pump-turbines becomes increasingly important in the course of the integration of renewable energy sources in the existing power grid. However, at partial load condition in pumping mode, the occurrence of rotating stall is critical to the operational safety of the machine and on the grid stability. The understanding of the mechanisms behind this flow phenomenon yet remains vague and incomplete. Past numerical simulations using a RANS approach often led to inconclusive results concerning the physical background. For the first time, the rotating stall is investigated by performing a large scale LES calculation on the HYDRODYNA pump-turbine scale model featuring approximately 100 million elements. The computations were performed on the PRIMEHPC FX10 of the University of Tokyo using the overset Finite Element open source code FrontFlow/blue with the dynamic Smagorinsky turbulence model and the no-slip wall condition. The internal flow computed is the one when operating the pump-turbine at 76% of the best efficiency point in pumping mode, as previous experimental research showed the presence of four rotating cells. The rotating stall phenomenon is accurately reproduced for a reduced Reynolds number using the LES approach with acceptable computing resources. The results show an excellent agreement with available experimental data from the reduced scale model testing at the EPFL Laboratory for Hydraulic Machines. The number of stall cells as well as the propagation speed corroborates the experiment.

  20. Earth Rotation

    Science.gov (United States)

    Dickey, Jean O.

    1995-01-01

    The study of the Earth's rotation in space (encompassing Universal Time (UT1), length of day, polar motion, and the phenomena of precession and nutation) addresses the complex nature of Earth orientation changes, the mechanisms of excitation of these changes and their geophysical implications in a broad variety of areas. In the absence of internal sources of energy or interactions with astronomical objects, the Earth would move as a rigid body with its various parts (the crust, mantle, inner and outer cores, atmosphere and oceans) rotating together at a constant fixed rate. In reality, the world is considerably more complicated, as is schematically illustrated. The rotation rate of the Earth's crust is not constant, but exhibits complicated fluctuations in speed amounting to several parts in 10(exp 8) [corresponding to a variation of several milliseconds (ms) in the Length Of the Day (LOD) and about one part in 10(exp 6) in the orientation of the rotation axis relative to the solid Earth's axis of figure (polar motion). These changes occur over a broad spectrum of time scales, ranging from hours to centuries and longer, reflecting the fact that they are produced by a wide variety of geophysical and astronomical processes. Geodetic observations of Earth rotation changes thus provide insights into the geophysical processes illustrated, which are often difficult to obtain by other means. In addition, these measurements are required for engineering purposes. Theoretical studies of Earth rotation variations are based on the application of Euler's dynamical equations to the problem of finding the response of slightly deformable solid Earth to variety of surface and internal stresses.

  1. Dynamic Time-Resolved Chirped-Pulse Rotational Spectroscopy of Vinyl Cyanide Photoproducts in a Room Temperature Flow Reactor

    Science.gov (United States)

    Zaleski, Daniel P.; Prozument, Kirill

    2017-06-01

    Chirped-pulsed (CP) Fourier transform rotational spectroscopy invented by Brooks Pate and coworkers a decade ago is an attractive tool for gas phase chemical dynamics and kinetics studies. A good reactor for such a purpose would have well-defined (and variable) temperature and pressure conditions to be amenable to accurate kinetic modeling. Furthermore, in low pressure samples with large enough number of molecular emitters, reaction dynamics can be observable directly, rather than mediated by supersonic expansion. In the present work, we are evaluating feasibility of in situ time-resolved CP spectroscopy in a room temperature flow tube reactor. Vinyl cyanide (CH_2CHCN), neat or mixed with inert gasses, flows through the reactor at pressures 1-50 μbar (0.76-38 mTorr) where it is photodissociated by a 193 nm laser. Millimeter-wave beam of the CP spectrometer co-propagates with the laser beam along the reactor tube and interacts with nascent photoproducts. Rotational transitions of HCN, HNC, and HCCCN are detected, with ≥10 μs time-steps for 500 ms following photolysis of CH_2CHCN. The post-photolysis evolution of the photoproducts' rotational line intensities is investigated for the effects of rotational and vibrational thermalization of energized photoproducts. Possible contributions from bimolecular and wall-mediated chemistry are evaluated as well.

  2. Internal friction due to domain-wall motion in martensitically transformed A15 compounds

    International Nuclear Information System (INIS)

    Snead, C.L. Jr.; Welch, D.O.

    1985-01-01

    A lattice instability in A15 materials in some cases leads to a cubic-to-tetragonal martensitic transformation at low temperatures. The transformed material orients in lamellae with c axes alternately aligned along the directions producing domain walls between the lamellae. An internal-friction (delta) feature below T/sub m/ is attributed to stress-induced domain-wall motion. The magnitude of the friction increases as temperature is lowered below T/sub m/ as (1-c/a) increases, and behaves as (1-c/a) 2 from T/sub m/ down to the superconducting critical temperature where the increasing tetragonality is inhibited. The effect of strain in the lattice is to decrease the domain-wall internal friction, but not affect T/sub m/. Neutron-induced disorder and the addition of some third-elements in alloying decrease both delta and T/sub m/, with some elements reducing only the former. Less than 1 at. % H is seen to completely suppress both delta and T/sub m. Martensitically transformed V 2 Zr demonstrates low-temperature internal-friction and modulus behavior consists with easy β/m wall motion relative to the easy m/m motion of the A15's. For the V 2 Zr, a peak in delta is observed, qualitatively in agreement with expected β/m wall motion

  3. Rotated alphanumeric characters do not automatically activate frontoparietal areas subserving mental rotation

    DEFF Research Database (Denmark)

    Weiss, Michael M; Wolbers, Thomas; Peller, Martin

    2008-01-01

    Functional neuroimaging studies have identified a set of areas in the intraparietal sulcus and dorsal precentral cortex which show a linear increase in activity with the angle of rotation across a variety of mental rotation tasks. This linear increase in activity with angular disparity suggests t...... modulated by angular disparity during the stimulus categorization task. These results suggest that at least for alphanumerical characters, areas implicated in mental rotation will only be called into action if the task requires a rotational transformation....

  4. Axisymmetric flow in a cylindrical tank over a rotating bottom. Part II. Deformation of the water surface and experimental verification of the theory

    Energy Technology Data Exchange (ETDEWEB)

    Iga, Keita; Watanabe, Shunichi; Niino, Hiroshi; Misawa, Nobuhiko [Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8564 (Japan); Yokota, Sho [Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki 305-0052 (Japan); Ikeda, Takashi, E-mail: iga@aori.u-tokyo.ac.jp [Japan Patent Office, 3-4-3 Kasumigaseki, Chiyoda, Tokyo 100-8915 (Japan)

    2017-12-15

    The theory of axisymmetric flow in a cylindrical container with a rotating bottom, as described in Part I, is validated against the results of previous and our own laboratory experiments. First, deformation of the water surface is derived using the velocity distribution of the axisymmetric flow obtained by the theory. The form of the water surface is classified into three regimes, and the rotation rates of the transitions between these regimes are determined. The parameters predicted from this theory are compared with the results measured in laboratory experiments and also with data from previous experimental studies. The theory predicts the experimental data well, but a slight difference was found in the narrow region close to the side wall. Corrections estimated by considering the fluid behavior around the side wall boundary layer successfully explain most of the discrepancies. This theory appears to predict the results of the laboratory experiments very well, much better than a theory using an assumption of quadratic drag as a model of turbulent boundary layers. (paper)

  5. Rotating D0-branes and consistent truncations of supergravity

    International Nuclear Information System (INIS)

    Anabalón, Andrés; Ortiz, Thomas; Samtleben, Henning

    2013-01-01

    The fluctuations around the D0-brane near-horizon geometry are described by two-dimensional SO(9) gauged maximal supergravity. We work out the U(1) 4 truncation of this theory whose scalar sector consists of five dilaton and four axion fields. We construct the full non-linear Kaluza–Klein ansatz for the embedding of the dilaton sector into type IIA supergravity. This yields a consistent truncation around a geometry which is the warped product of a two-dimensional domain wall and the sphere S 8 . As an application, we consider the solutions corresponding to rotating D0-branes which in the near-horizon limit approach AdS 2 ×M 8 geometries, and discuss their thermodynamical properties. More generally, we study the appearance of such solutions in the presence of non-vanishing axion fields

  6. The cost-effectiveness of single-row compared with double-row arthroscopic rotator cuff repair.

    Science.gov (United States)

    Genuario, James W; Donegan, Ryan P; Hamman, Daniel; Bell, John-Erik; Boublik, Martin; Schlegel, Theodore; Tosteson, Anna N A

    2012-08-01

    Interest in double-row techniques for arthroscopic rotator cuff repair has increased over the last several years, presumably because of a combination of literature demonstrating superior biomechanical characteristics and recent improvements in instrumentation and technique. As a result of the increasing focus on value-based health-care delivery, orthopaedic surgeons must understand the cost implications of this practice. The purpose of this study was to examine the cost-effectiveness of double-row arthroscopic rotator cuff repair compared with traditional single-row repair. A decision-analytic model was constructed to assess the cost-effectiveness of double-row arthroscopic rotator cuff repair compared with single-row repair on the basis of the cost per quality-adjusted life year gained. Two cohorts of patients (one with a tear of row compared with single-row arthroscopic rotator cuff repair was $571,500 for rotator cuff tears of row repair was less than $287 for small or moderate tears and less than $352 for large or massive tears compared with the cost of single-row repair, then double-row repair would represent a cost-effective surgical alternative. On the basis of currently available data, double-row rotator cuff repair is not cost-effective for any size rotator cuff tears. However, variability in the values for costs and probability of retear can have a profound effect on the results of the model and may create an environment in which double-row repair becomes the more cost-effective surgical option. The identification of the threshold values in this study may help surgeons to determine the most cost-effective treatment.

  7. Experimental studies of tearing mode and resistive wall mode dynamics in the reversed field pinch configuration

    International Nuclear Information System (INIS)

    Malmberg, Jenny-Ann

    2003-06-01

    It is relatively straightforward to establish equilibrium in magnetically confined plasmas, but the plasma is frequently susceptible to a variety of instabilities that are driven by the free energy in the magnetic field or in the pressure gradient. These unstable modes exhibit effects that affect the particle, momentum and heat confinement properties of the configuration. Studies of the dynamics of several of the most important modes are the subject of this thesis. The studies are carried out on plasmas in the reversed field pinch (RFP) configuration. One phenomenon commonly observed in RFPs is mode wall locking. The localized nature of these phase- and wall locked structures results in localized power loads on the wall which are detrimental for confinement. A detailed study of the wall locked mode phenomenon is performed based on magnetic measurements from three RFP devices. The two possible mechanisms for wall locking are investigated. Locking as a result of tearing modes interacting with a static field error and locking due to the presence of a non-ideal boundary. The characteristics of the wall locked mode are qualitatively similar in a device with a conducting shell system (TPE-RX) compared to a device with a resistive shell (Extrap T2). A theoretical model is used for evaluating the threshold values for wall locking due to eddy currents in the vacuum vessel in these devices. A good correlation with experiment is observed for the conducting shell device. The possibility of successfully sustaining discharges in a resistive shell RFP is introduced in the recently rebuilt device Extrap T2R. Fast spontaneous mode rotation is observed, resulting in low magnetic fluctuations, low loop voltage and improved confinement. Wall locking is rarely observed. The low tearing mode amplitudes allow for the theoretically predicted internal non-resonant on-axis resistive wall modes to be observed. These modes have not previously been distinguished due to the formation of wall

  8. Rotating dryer

    International Nuclear Information System (INIS)

    Noe, C.

    1984-01-01

    Products to dry are introduced inside a rotating tube placed in an oven, the cross section of the tube is an arc of spiral. During clockwise rotation of the tube products are maintained inside and mixed, during anticlockwise products are removed. Application is made to drying of radioactive wastes [fr

  9. Rotating Wavepackets

    Science.gov (United States)

    Lekner, John

    2008-01-01

    Any free-particle wavepacket solution of Schrodinger's equation can be converted by differentiations to wavepackets rotating about the original direction of motion. The angular momentum component along the motion associated with this rotation is an integral multiple of [h-bar]. It is an "intrinsic" angular momentum: independent of origin and…

  10. EXERCISE REHABILITATION IN THE NON-OPERATIVE MANAGEMENT OF ROTATOR CUFF TEARS: A REVIEW OF THE LITERATURE

    Science.gov (United States)

    Edwards, Peter; Ebert, Jay; Joss, Brendan; Bhabra, Gev; Ackland, Tim; Wang, Allan

    2016-01-01

    The incidence of rotator cuff tears increases with age, with full-thickness rotator cuff tears present in approximately 25% of individuals in their sixties, and more than 50% of those in their eighties. While surgery is considered an effective treatment, recurrent tears at the insertion site are common, especially with degenerative tears, which are frequent in the older population. More recently, there has been increasing interest in exercise rehabilitation and physical therapy as a means to manage partial and full thickness tears of the rotator cuff by addressing weakness and functional deficits. Recent studies have suggested that patients opting for physical therapy have demonstrated high satisfaction, an improvement in function, and success in avoiding surgery. When considering the increasing rate of shoulder surgery and the associated economic and social burden rotator cuff surgery places on both the patient and the health care system, non-surgical management such as physical therapy and exercise may, in selected cases, be a treatment alternative to surgical repair. The purpose of this clinical commentary is to provide an overview of rotator cuff pathology and pathogenesis, and to present an evidence-based case for the role of conservative rehabilitation in the management of rotator cuff injuries. Level of Evidence Level 5 PMID:27104061

  11. Rotator cuff - self-care

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000358.htm Rotator cuff - self-care To use the sharing features on ... and shoulder exercises may help ease your symptoms. Rotator Cuff Problems Common rotator cuff problems include: Tendinitis , which ...

  12. Examining cotton in rotation with rice and cotton in rotation with other crops using natural experiment

    Science.gov (United States)

    Sun, Ling; Zhu, Zesheng

    2017-08-01

    This paper is to show the ability of remote sensing image analysis combined with statistical analysis to characterize the environmental risk assessment of cotton in rotation with rice and cotton in rotation with other crops in two ways: (1) description of rotation period of cotton in rotation with rice and cotton in rotation with other crops by the observational study or natural experiment; (2) analysis of rotation period calculation of cotton in rotation with rice and cotton in rotation with other crops. Natural experimental results show that this new method is very promising for determining crop rotation period for estimating regional averages of environmental risk. When it is applied to determining crop rotation period, two requested remote sensing images of regional crop are required at least.

  13. WE-DE-201-08: Multi-Source Rotating Shield Brachytherapy Apparatus for Prostate Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Dadkhah, H; Wu, X [University of Iowa, Iowa City, Iowa (United States); Kim, Y; Flynn, R [University of Iowa Hospitals and Clinics, Iowa City, IA (United States)

    2016-06-15

    Purpose: To introduce a novel multi-source rotating shield brachytherapy (RSBT) apparatus for the precise simultaneous angular and linear positioning of all partially-shielded 153Gd radiation sources in interstitial needles for treating prostate cancer. The mechanism is designed to lower the detrimental dose to healthy tissues, the urethra in particular, relative to conventional high-dose-rate brachytherapy (HDR-BT) techniques. Methods: Following needle implantation, the delivery system is docked to the patient template. Each needle is coupled to a multi-source afterloader catheter by a connector passing through a shaft. The shafts are rotated by translating a moving template between two stationary templates. Shaft walls as well as moving template holes are threaded such that the resistive friction produced between the two parts exerts enough force on the shafts to bring about the rotation. Rotation of the shaft is then transmitted to the shielded source via several keys. Thus, shaft angular position is fully correlated with the position of the moving template. The catheter angles are simultaneously incremented throughout treatment as needed, and only a single 360° rotation of all catheters is needed for a full treatment. For each rotation angle, source depth in each needle is controlled by a multi-source afterloader, which is proposed as an array of belt-driven linear actuators, each of which drives a source wire. Results: Optimized treatment plans based on Monte Carlo dose calculations demonstrated RSBT with the proposed apparatus reduced urethral D{sub 1cc} below that of conventional HDR-BT by 35% for urethral dose gradient volume within 3 mm of the urethra surface. Treatment time to deliver 20 Gy with multi-source RSBT apparatus using nineteen 62.4 GBq {sup 153}Gd sources is 117 min. Conclusions: The proposed RSBT delivery apparatus in conjunction with multiple nitinol catheter-mounted platinum-shielded {sup 153}Gd sources enables a mechanically feasible

  14. Jet Engine Bird Ingestion Simulations: Comparison of Rotating to Non-Rotating Fan Blades

    Science.gov (United States)

    Howard, Samuel A.; Hammer, Jeremiah T.; Carney, Kelly S.; Pereira, J. Michael

    2013-01-01

    Bird strike events in commercial airliners are a fairly common occurrence. According to data collected by the US Department of Agriculture, over 80,000 bird strikes were reported in the period 1990 to 2007 in the US alone (Ref. 1). As a result, bird ingestion is an important factor in aero engine design and FAA certification. When it comes to bird impacts on engine fan blades, the FAA requires full-scale bird ingestion tests on an engine running at full speed to pass certification requirements. These rotating tests are complex and very expensive. To reduce development costs associated with new materials for fan blades, it is desirable to develop more cost effective testing procedures than full-scale rotating engine tests for material evaluation. An impact test on a nonrotating single blade that captures most of the salient physics of the rotating test would go a long way towards enabling large numbers of evaluative material screening tests. NASA Glenn Research Center has been working to identify a static blade test procedure that would be effective at reproducing similar results as seen in rotating tests. The current effort compares analytical simulations of a bird strike on various non-rotating blades to a bird strike simulation on a rotating blade as a baseline case. Several different concepts for simulating the rotating loads on a non-rotating blade were analyzed with little success in duplicating the deformation results seen in the rotating case. The rotating blade behaves as if it were stiffer than the non-rotating blade resulting in less plastic deformation from a given bird impact. The key factor limiting the success of the non-rotating blade simulations is thought to be the effect of gyroscopics. Prior to this effort, it was anticipated the difficulty would be in matching the prestress in the blade due to centrifugal forces Additional work is needed to verify this assertion, and to determine if a static test procedure can simulate the gyroscopic effects in

  15. Bulk Fluidity and Apparent Wall Slip of Aqueous Kaolin Suspensions Studied Using the Cone-Cone (KK) Sensor: Effect of the Sensor Surface Quality.

    Czech Academy of Sciences Publication Activity Database

    Pěnkavová, Věra; Tihon, Jaroslav; Wein, Ondřej

    2017-01-01

    Roč. 533, NOV 20 (2017), s. 338-346 ISSN 0927-7757 EU Projects: Foundation for Science and Technology(XE) MP1305 Institutional support: RVO:67985858 Keywords : aqueous kaolin suspensions * rotational AWS viscometry * apparent wall slip Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 2.714, year: 2016

  16. Simulated Microgravity Regulates Gene Transcript Profiles of 2T3 Preosteoblasts: Comparison of the Random Positioning Machine and the Rotating Wall Vessel Bioreactor

    Science.gov (United States)

    Patel, Mamta J.; Liu, Wenbin; Sykes, Michelle C.; Ward, Nancy E.; Risin, Semyon A.; Risin, Diana; Hanjoong, Jo

    2007-01-01

    Microgravity of spaceflight induces bone loss due in part to decreased bone formation by osteoblasts. We have previously examined the microgravity-induced changes in gene expression profiles in 2T3 preosteoblasts using the Random Positioning Machine (RPM) to simulate microgravity conditions. Here, we hypothesized that exposure of preosteoblasts to an independent microgravity simulator, the Rotating Wall Vessel (RWV), induces similar changes in differentiation and gene transcript profiles, resulting in a more confined list of gravi-sensitive genes that may play a role in bone formation. In comparison to static 1g controls, exposure of 2T3 cells to RWV for 3 days inhibited alkaline phosphatase activity, a marker of differentiation, and downregulated 61 genes and upregulated 45 genes by more than two-fold as shown by microarray analysis. The microarray results were confirmed with real time PCR for downregulated genes osteomodulin, bone morphogenic protein 4 (BMP4), runx2, and parathyroid hormone receptor 1. Western blot analysis validated the expression of three downregulated genes, BMP4, peroxiredoxin IV, and osteoglycin, and one upregulated gene peroxiredoxin I. Comparison of the microarrays from the RPM and the RWV studies identified 14 gravi-sensitive genes that changed in the same direction in both systems. Further comparison of our results to a published database showing gene transcript profiles of mechanically loaded mouse tibiae revealed 16 genes upregulated by the loading that were shown to be downregulated by RWV and RPM. These mechanosensitive genes identified by the comparative studies may provide novel insights into understanding the mechanisms regulating bone formation and potential targets of countermeasure against decreased bone formation both in astronauts and in general patients with musculoskeletal disorders.

  17. Observation and Characterization of Fragile Organometallic Molecules Encapsulated in Single-Wall Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Daisuke Ogawa

    2014-01-01

    Full Text Available Thermally fragile tris(η5-cyclopentadienylerbium (ErCp3 molecules are encapsulated in single-wall carbon nanotubes (SWCNTs with high yield. We realized the encapsulation of ErCp3 with high filling ratio by using high quality SWCNTs at an optimized temperature under higher vacuum. Structure determination based on high-resolution transmission electron microscope observations together with the image simulations reveals the presence of almost free rotation of each ErCp3 molecule in SWCNTs. The encapsulation is also confirmed by X-ray diffraction. Trivalent character of Er ions (i.e., Er3+ is confirmed by X-ray absorption spectrum.

  18. Rotating Stars in Relativity

    Directory of Open Access Journals (Sweden)

    Stergioulas Nikolaos

    2003-01-01

    Full Text Available Rotating relativistic stars have been studied extensively in recent years, both theoretically and observationally, because of the information they might yield about the equation of state of matter at extremely high densities and because they are considered to be promising sources of gravitational waves. The latest theoretical understanding of rotating stars in relativity is reviewed in this updated article. The sections on the equilibrium properties and on the nonaxisymmetric instabilities in f-modes and r-modes have been updated and several new sections have been added on analytic solutions for the exterior spacetime, rotating stars in LMXBs, rotating strange stars, and on rotating stars in numerical relativity.

  19. Experimental and theoretical studies of active control of resistive wall mode growth in the EXTRAP T2R reversed-field pinch

    International Nuclear Information System (INIS)

    Drake, J.R.; Brunsell, P.R.; Yadikin, D.; Cecconello, M.; Malmberg, J.A.; Gregoratto, D.; Paccagnella, R.; Bolzonella, T.; Manduchi, G.; Marrelli, L.; Ortolani, S.; Spizzo, G.; Zanca, P.; Bondeson, A.; Liu, Y.Q.

    2005-01-01

    Active feedback control of resistive wall modes (RWMs) has been demonstrated on the EXTRAP T2R reversed-field pinch experiment. The control system includes a sensor consisting of an array of magnetic coils (measuring mode harmonics) and an actuator consisting of a saddle coil array (producing control harmonics). Closed-loop (feedback) experiments using a digital controller based on a real time Fourier transform of sensor data have been studied for cases where the feedback gain was constant and real for all harmonics (intelligent-shell) and cases where the feedback gain could be set for selected harmonics, with both real or complex values (targeted-harmonics). The growth of the dominant RWMs can be suppressed by feedback for both the intelligent-shell and targeted-harmonic control systems. Because the number of toroidal positions of saddle coils in the array is half the number of sensors, it is predicted and observed experimentally that the control harmonic spectrum has sidebands. As a result, each control harmonic has to control simultaneously two mode harmonics. Real gains can stabilize non-rotating RWMs, while complex gains give better results for (slowly) rotating RWMs. In addition open loop experiments have been used to observe the effects of resonant field errors applied to unstable, marginally stable and robustly stable modes. The observed effects of field errors are consistent with the thin-wall model, where mode growth is proportional to the resonant field error amplitude and the wall penetration time for that mode harmonic. (author)

  20. Magnetization rotation or generation of incoherent spin waves? Suggestions for a spin-transfer effect experiment

    International Nuclear Information System (INIS)

    Bazaliy, Y. B.; Jones, B. A.

    2002-01-01

    ''Spin-transfer'' torque is created when electric current is passed through metallic ferromagnets and may have interesting applications in spintronics. So far it was experimentally studied in ''collinear'' geometries, where it is difficult to predict whether magnetization will coherently rotate or spin-waves will be generated. Here we propose an easy modification of existing experiment in which the spin-polarization of incoming current will no longer be collinear with magnetization and recalculate the switching behavior of the device. We expect that a better agreement with the magnetization rotation theory will be achieved. That can be an important step in reconciling alternative points of view on the effect of spin-transfer torque