WorldWideScience

Sample records for collective flow studies

  1. Flowing together : a longitudinal study of collective efficacy and collective flow among workgroups.

    Salanova, Marisa; Rodríguez-Sánchez, Alma M.; Schaufeli, Wilmar B.; Cifre, Eva

    2014-01-01

    The aim of this study is to extend the Channel Model of Flow (Csikszentmihalyi, 1975, 1990) at the collective level (workgroups) by including collective efficacy beliefs as a predictor of collective flow based on the Social Cognitive Theory (Bandura, 1997, 2001). A two-wave longitudinal lab study

  2. Study on an Axial Flow Hydraulic Turbine with Collection Device

    Yasuyuki Nishi

    2014-01-01

    Full Text Available We propose a new type of portable hydraulic turbine that uses the kinetic energy of flow in open channels. The turbine comprises a runner with an appended collection device that includes a diffuser section in an attempt to improve the output by catching and accelerating the flow. With such turbines, the performance of the collection device, and a composite body comprising the runner and collection device were studied using numerical analysis. Among four stand-alone collection devices, the inlet velocity ratio was most improved by the collection device featuring an inlet nozzle and brim. The inlet velocity ratio of the composite body was significantly lower than that of the stand-alone collection device, owing to the resistance of the runner itself, the decreased diffuser pressure recovery coefficient, and the increased backpressure coefficient. However, at the maximum output tip speed ratio, the inlet velocity ratio and the loading coefficient were approximately 31% and 22% higher, respectively, for the composite body than for the isolated runner. In particular, the input power coefficient significantly increased (by approximately 2.76 times owing to the increase in the inlet velocity ratio. Verification tests were also conducted in a real canal to establish the actual effectiveness of the turbine.

  3. Progress in collective flow studies from the onset to Bevalac/SIS

    Lisa, M.A.

    1995-03-01

    Collective flow in heavy ion collisions was first observed experimentally more than a decade ago at the Bevalac by the Plastic Ball collaboration. Although early calculations had suggested that measurement of the flow would place tight constraints on the nuclear equation of state, uncertainties in other input parameters of microscopic models, which also affect the flow, led to large ambiguities in the equation of state. This talk will discuss recent flow studies that attempt to overcome these difficulties. The EOS and FOPI experiments at the Bevalac and SIS accelerators have measured flow in the 200--2000 A-MeV bombarding energy range with better acceptance, particle identification, and systematics than was previously available. Meanwhile, programs at MSU and GANIL are studying the disappearance of flow around 50 A-MeV. Systematic comparison of these data with predictions of microscopic models is beginning to reduce the ambiguities in the extraction of physics quantities. Also, new directions in flow studies, such as the flow of produced particles and radial flow, offer the possibility of further information from flow studies. Recent accomplishments and new directions in flow studies are discussed, and areas where further study is needed are pointed out

  4. Hydrodynamical description of collective flow

    Huovinen, Pasi

    2003-01-01

    I review how hydrodynamical flow is related to the observed flow in ultrarelativistic heavy ion collisions and how initial conditions, equation of state and freeze-out temperature affect flow in hydrodynamical models.

  5. Collective flow studies in central collisions between nuclei at several hundreds of MeV per nucleon

    Demoulins, M.

    1990-02-01

    The main purpose for studying collisions between heavy nuclei, in the 200-2000 MeV per nucleon energy range, is to determine the equation of state and the properties of dense and hot nuclear matter. The insensitiveness of the inclusive data to the equation of state has led experimental physicists to build large solid angle detectors capable of detecting simultaneously the tens of particles emitted in each event. Such measurements allow to estimate the impact parameter, the reaction plane on an event-by-event basis, and to calculate various global variables involving all particles emitted in each event. In this thesis, we study global variables which characterize the nuclear matter collective flow in a direction which is different from the direction of incident motion, for argon-nucleus collisions at 400 and 600 MeV by nucleon and for neon-nucleus collisions at 400 and 800 MeV by nucleon. The measurements have been performed with the DIOGENE detector installed at SATURNE. For the argon-beam experiments, two parallel plate avalanche counters have been used to locate the interaction point of each incoming ion with the target, which improves the reconstruction of the particle tracks in the DIOGENE central chamber. Double differential cross-sections, in the reaction plane and in the plane orthogonal to the reaction plane, are fitted with two-dimensional Gaussian distributions. Through this procedure, we get rid of geometrical acceptance effects. Several quantities, related to the collective flow (flow angle, aspect ratios, flow parameter), are thus extracted and corrected for the fluctuations of the estimated reaction plane. For argon-nucleus collisions at 400 MeV by nucleon, our results are in agreement with results obtained by other groups with different methods. For argon-nucleus collisions, the discrepancy between our experimental results and predictions of intranuclear cascade calculations is increasing with the mass asymmetry of the colliding system [fr

  6. Collective flow studies in central collisions between nuclei at several hundreds of MeV per nucleon

    Demoulins, M.

    1989-01-01

    The main purpose for studying collisions between heavy nuclei, in the 200-2000 MeV per nucleon energy range, is to determine the equation of state and the properties of dense and hot nuclear matter. The insensitiveness of the inclusive data to the equation of state has led experimental physicists to build large solid angle detectors capable of detecting simultaneously the tens of particles emitted in each event. Such measurements allow to estimate the impact parameter, the reaction plane on an event-by-event basis, and to calculate various global variables involving all particles emitted in each event. In this thesis, we study global variables which characterize the nuclear matter collective flow in a direction which is different from the direction of incident motion, for argon-nucleus collisions at 400 and 600 MeV by nucleon and for neon-nucleus collisions at 400 and 800 MeV by nucleon. The measurements have been performed with the DIOGENE detector installed at SATURNE. For the argon-beam experiments, two parallel plate avalanche counters have been used to locate the interaction point of each incoming ion with the target, which improves the reconstruction of the particle tracks in the DIOGENE central chamber. Double differential cross sections, in the reaction plane and in the plane orthogonal to the reaction plane, are fitted with two-dimensional Gaussian distributions. Through this procedure, we get rid of geometrical acceptance effects. Several quantities, related to the collective flow (flow angle, aspect ratios, flow parameter), are thus extracted and corrected for the fluctuations of the estimated reaction plane. For the argon-nucleus collisions at 400 MeV by nucleon, our results are in agreement with results obtained by other groups with different methods. For argon-nucleus collisions, the discrepancy between our experimental results and predictions of intranuclear cascade calculations is increasing with the mass asymmetry of the colliding system [fr

  7. Collective flow measured with the Plastic Ball

    Ritter, H.G.; Gutbrod, H.H.; Kampert, K.H.; Kolb, B.; Poskanzer, A.M.; Schicker, R.; Schmidt, H.R.; Siemiarczuk, T.

    1989-08-01

    The experimental results from the Plastic Ball detector have contributed vastly to the understanding of the reaction mechanism of nuclear collisions at several hundred MeV per nucleon. The discovery of the collective flow phenomena (bounce-off of spectator fragments, side-splash in the reaction plane, and squeeze-out out of the reaction plane), as they were predicted by hydrodynamical models, has led to the experimental observation of compressed nuclear matter, which is a necessary condition before one can study the equation of state in detail and search for phase transitions at higher energies. 39 refs., 9 figs., 1 tab

  8. A Geometric Representation of Collective Attention Flows.

    Peiteng Shi

    Full Text Available With the fast development of Internet and WWW, "information overload" has become an overwhelming problem, and collective attention of users will play a more important role nowadays. As a result, knowing how collective attention distributes and flows among different websites is the first step to understand the underlying dynamics of attention on WWW. In this paper, we propose a method to embed a large number of web sites into a high dimensional Euclidean space according to the novel concept of flow distance, which both considers connection topology between sites and collective click behaviors of users. With this geometric representation, we visualize the attention flow in the data set of Indiana university clickstream over one day. It turns out that all the websites can be embedded into a 20 dimensional ball, in which, close sites are always visited by users sequentially. The distributions of websites, attention flows, and dissipations can be divided into three spherical crowns (core, interim, and periphery. 20% popular sites (Google.com, Myspace.com, Facebook.com, etc. attracting 75% attention flows with only 55% dissipations (log off users locate in the central layer with the radius 4.1. While 60% sites attracting only about 22% traffics with almost 38% dissipations locate in the middle area with radius between 4.1 and 6.3. Other 20% sites are far from the central area. All the cumulative distributions of variables can be well fitted by "S"-shaped curves. And the patterns are stable across different periods. Thus, the overall distribution and the dynamics of collective attention on websites can be well exhibited by this geometric representation.

  9. A Geometric Representation of Collective Attention Flows.

    Shi, Peiteng; Huang, Xiaohan; Wang, Jun; Zhang, Jiang; Deng, Su; Wu, Yahui

    2015-01-01

    With the fast development of Internet and WWW, "information overload" has become an overwhelming problem, and collective attention of users will play a more important role nowadays. As a result, knowing how collective attention distributes and flows among different websites is the first step to understand the underlying dynamics of attention on WWW. In this paper, we propose a method to embed a large number of web sites into a high dimensional Euclidean space according to the novel concept of flow distance, which both considers connection topology between sites and collective click behaviors of users. With this geometric representation, we visualize the attention flow in the data set of Indiana university clickstream over one day. It turns out that all the websites can be embedded into a 20 dimensional ball, in which, close sites are always visited by users sequentially. The distributions of websites, attention flows, and dissipations can be divided into three spherical crowns (core, interim, and periphery). 20% popular sites (Google.com, Myspace.com, Facebook.com, etc.) attracting 75% attention flows with only 55% dissipations (log off users) locate in the central layer with the radius 4.1. While 60% sites attracting only about 22% traffics with almost 38% dissipations locate in the middle area with radius between 4.1 and 6.3. Other 20% sites are far from the central area. All the cumulative distributions of variables can be well fitted by "S"-shaped curves. And the patterns are stable across different periods. Thus, the overall distribution and the dynamics of collective attention on websites can be well exhibited by this geometric representation.

  10. The study of the components of matter collective flow in the collisions of 64 Zn on 58 Ni at 35 to 79 MeV/u

    Popescu, R.

    1995-06-01

    In a nucleus-nucleus collision the collective motion of matter, emitted from the overlapping region, give information on the properties of nuclear matter out-of-equilibrium. The characteristics of this motion have been studied on the 64 Zn on 58 Ni system up to 79 MeV per nucleon, using the flow parameter and the azimuthal distributions. We studied the evolution of those quantities with the incident energy, the impact parameter and the charge of particle. The experiment has been done at GANIL using the multidetectors of light particles and fragments, Mur and Tonneau. For estimating the impact parameter, two global variables have been used: the average parallel velocity and the total perpendicular momentum. For determining the reaction plane two methods have been used: the transverse momentum analysis and the azimuthal correlation method. The results are not sensitive to the global variable or method. The measured values revealed the inversion of the direction of sideward flow. The energy of vanishing flow ranges from 55 to 75 MeV per nucleon when the impact parameter increases from 1 to 6 fm. In the same way, the aspect of the azimuthal distribution changes from in-plane to out-of-plane enhancement when the energy increases, providing with a new indication of change in the interaction dynamics. The energy of isotropic emission lies between 45 and 65 MeV per nucleon depending of the impact parameter. For alpha particles, the flow parameter and the azimuthal asymmetry are greater than for protons, due to a smaller thermal dispersion. A Landau-Vlasov model using a non-local Gogny force is able to reproduce the global characteristics experimentally observed (rapidity and transverse momentum distributions). The calculated flow and azimuthal asymmetry values reproduce the experimental ones for an incompressibility modulus near 230 MeV. The study of the dependence on nucleon-nucleon cross section in nuclear medium must be pursued. (author)

  11. Flow shapes and higher harmonics in anisotropic transverse collective flow

    Argintaru, Danut; Baban, Valerica [Constanta Maritime University, Faculty of Navigation and Naval Transport, Constanta (Romania); Besliu, Calin; Jipa, Alexandru; Grossu, Valeriu [University of Bucharest, Faculty of Physics, Bucharest (Romania); Esanu, Tiberiu; Cherciu, Madalin [Institute of Space Sciences Bucharest-Magurele, Bucharest (Romania)

    2017-01-15

    In this paper we show that by using a jet-finder algorithm (the Anti-k{sub T} one) on UrQMD/C simulated (Au+Au at 4, 10 and 15A GeV) collisions, we can identify different flow shape structures (single flow stream events, two flow streams events, three flow streams events, etc.) and order the bulk of events in equivalence flow shape classes. Considering these flow streams as the main directions of anisotropic transverse flow, we show that the Fourier coefficients v{sub n} of anisotropic flow are better emphasized when we analyze the different event flow shape classes than when the events are mixed. Also, if we do not know the real orientation of the reaction plane, we can use as reference the Flow stream 1 - the main particle flow stream - orientation (Ψ{sub Flowstream} {sub 1}) to highlight the initial shape of the participant nuclear matter in a central to peripheral collision, and the orientation of the participant plane of order n. (orig.)

  12. Nuclear collective flow from gaussian fits to triple differential distributions

    Gosset, J.; Demoulins, M.; Babinet, R.; Cavata, C.; Fanet, H.; L'Hote, D.; Lucas, B.; Poitou, J.; Valette, O.; Alard, J.P.; Augerat, J.; Bastid, N.; Charmensat, P.; Dupieux, P.; Fraysse, L.; Marroncle, J.; Montarou, G.; Parizet, M.J.; Qassoud, D.; Rahmani, A.; Brochard, F.; Gorodetzky, P.; Racca, C.

    1990-01-01

    In order to study the nuclear collective flow, the triple differential momentum distributions of charged baryons are fitted to a simple anisotropic gaussian distribution, within an acceptance which removes most of the spectator contribution. The adjusted flow angle and aspect ratios are corrected for systematic errors in the determination of the reaction plane. This method has been tested with Monte Carlo simulations and applied to experimental results and intranuclear cascade simulations of argon-nucleus collisions at 400 MeV per nucleon. (orig.)

  13. Enriched lithium collection from lithium plasma flow

    Karchevsky, A.I.; Laz'ko, V.S.; Muromkin, Y.A.; Pashkovsky, V.G.; Ustinov, A.L.; Dolgolenko, D.A.

    1994-01-01

    In order to understand the physical processes concerned with the selective heating by ion cyclotron resonance and with the subsequent collection of heated particles, experiments were carried out with the extraction of lithium samples, enriched with 6 Li isotopes. Probe and integral extractors allow to collect enriched Li at the end of the selective heating region. Surface density distribution on the collector and local isotopic content of lithium are measured, as a function of the screen height and the retarding potential. Dependence of the collected amount of lithium and of its isotopic content on the value of the magnetic field is also measured. 4 figs., 2 tabs., 5 refs

  14. Inversion of collective matter flow and equation of state

    Peter, J.

    1992-03-01

    The multidetector array Mur + Tonneau has been used to perform a 4π detection of charged particles and fragments emitted in reactions at energies ranging from 25 to 95 MeV/u. The collective transverse momentum in the reaction plane (sidewards flow parameter) is observed to strongly vary as a function of impact parameter and incident energy. The measured values have to be corrected for the effects due to the error on the reaction plane determination and to the detector limitations. Those limitations caused by the method itself are more important than those caused by the detector. The flow value changes from negative values (negative scattering at low energies). The inversion (or balance) energy is in the range 50-100 MeV/u, depending on the system and impact parameter value. Comparisons between experimental data and theoretical values are shown for the system 40 Ar + 27 Al. These studies (BUU, Landau-Vlasov, QMD) show that the flow, and especially the inversion energy, is sensitive to the nucleon-nucleon cross section σNN in medium. The data indicate that a momentum dependent effective interaction should be used. Then, the flow value is not much sensitive to the incompressibility modulus K, but possibly in peripheral collisions. Additional observables should be used. The azimuthal distribution of mid-rapidity particles indicates a rotation-like behaviour of the interaction region

  15. Nuclear collective flow from gaussian fits to triple differential distributions

    Gosset, J.; Babinet, R.; Cavata, C.; Marco, M. de; Demoulins, M.; Fanet, H.; Fodor, Z.; L'Hote, D.; Lucas, B.

    1990-01-01

    A simple characterization of triple differential cross sections is needed for a systematic study of the nuclear matter collective flow in relativistic nucleus-nucleus collisions. Our analysis is based upon a fitting procedure, so that the triple differential distributions need not be measured in the whole momentum space. If the detector acceptance eliminates most spectator particles or if it is artificially restricted for doing so, this method leads to a flow characterization of the participant nuclear matter. The center-of-mass triple-differential momentum distributions are fitted to a simple analytical shape, namely an anisotropic Gaussian distribution. The adjusted parameters (flow angle and aspect ratios) are corrected for uncertainty in the event-by-event determination of the reaction plane azimuth (finite-number effects). Results are presented for neon-nucleus and argon-nucleus collisions at incident energy between 400 and 800 MeV per nucleon. Flow is already significant for light systems, and depends clearly upon the impact parameter

  16. The Role of Collective Flow in Heavy Ion Collisions

    Ritter, Hans Georg

    2007-01-01

    The motivation for flow measurements and the actual measurements at different energy domains are reviewed. At energies around 1 AGeV flow measurements have yielded information about the equation of state of nuclear matter. At RHIC energies partonic collectivity has been established.

  17. Radial collective flow in heavy-ion collisions at intermediate energies

    Borderie, B.

    1996-11-01

    The production of radial collective flow is associated with collisions leading to sources which undergo multifragmentation/explosion processes. After a theoretical survey of possible causes of production of radial flow, methods used to derive experimental values are discussed. Finally, a large set of data is presented which can be used to study and disentangle the different effects leading to radial collective flow. The dominant role of compression in the lower energy domain is emphasized. (author)

  18. Collective flow of pions in relativistic heavy-ion collisions

    Russkikh, V.N.; Ivanov, Yu.B.

    1995-02-01

    The transverse-momentum distributions of pions in the Au(1 GeV/nucleon)+Au collisions are analyzed. The calculations are carried out within relativistic meanfield one- and two-fluid models. The rapidity distributions of the mean transverse momentum of pions are found to be fairly sensitive to the nuclear equation of state and, especially, to the stopping power. It is shown that the collective flow of pions in the reaction plane always correlates with the 'hot' flow of nucleons (i.e. those emitted from hot regions of nuclear system), while not always, with the total nucleon flow. This 'hot' nucleon flow can be experimentally singled out by selecting nucleons with sufficiently high transverse momenta. We predict that the 'hot' nucleon flow selected in this way will always correlate with the pion flow. Available experimental data on transverse-momentum spectra of pions are compared with calculations employing various equations of state and stopping power. (orig.)

  19. Signatures of collective flow in high multiplicity pp collisions

    Kisiel, Adam

    2011-01-01

    A blast-wave parametrization, including a full set of hadronic resonances, is used to model a small system, with total particle multiplicity comparable to the one measured in the high-multiplicity pp collisions at the LHC. Calculations are preformed for three cases: with negligible, regular and strong radial flow on the blast-wave hypersurface. We investigate the effects of flow on inclusive p_T spectra as well as on 1D and 3D femtoscopic radii for pions. Special emphasis is put on the role of pions from resonance decays. In particular we show that they magnify the flow effects present in the blast-wave stage and significantly influence the shape of the correlation functions. A specific observable, the R^E_out/R^G_side ratio is proposed as a sensitive probe of the collective effects. Model results for the high multiplicity pp collisions, for scenarios with small and large radial flow are compared.

  20. Study of collective flows of protons and π{sup -}-mesons in p+C, Ta and He+Li, C collisions at momenta of 4.2, 4.5 and 10 AGeV/c

    Chkhaidze, L.; Djobava, T.; Kharkhelauri, L. [High Energy Physics Institute of Tbilisi State University, Tbilisi (Georgia); Chlachidze, G. [Fermi National Accelerator Laboratory, Batavia, IL (United States); Galoyan, A. [Joint Institute for Nuclear Research, Veksler and Baldin Laboratory of High Energy Physics, Dubna (Russian Federation); Togoo, R. [Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulan Bator (Mongolia); Uzhinsky, V. [Joint Institute for Nuclear Research, Laboratory of Information Technologies, Dubna (Russian Federation)

    2016-11-15

    Collective flows of protons and π{sup -}-mesons are studied at the momenta of 4.2, 4.5 and 10 AGeV/c for p+C, Ta and He+Li, C interactions. The data were obtained from the streamer chamber (SKM-200-GIBS) and from the Propane Bubble Chamber (PBC-500) systems utilized at JINR. A method of Danielewicz and Odyniec has been employed in determining a directed transverse flow of particles. The values of the transverse flow parameter and the strength of the anisotropic emission were defined for each interacting nuclear pair. It is found that the directed flows of protons and pions decrease with increasing the energy and the mass numbers of colliding nucleus pairs. The π{sup -}-meson and proton flows exhibit opposite directions in all studied interactions, and the flows of protons are directed in the reaction plane. The Ultra-relativistic Quantum Molecular Dynamical Model (UrQMD) coupled with the Statistical Multi-fragmentation Model (SMM), satisfactorily describes the obtained experimental results. (orig.)

  1. Multiplicity fluctuations and collective flow in small colliding systems

    Kawaguchi, Koji; Murase, Koichi; Hirano, Tetsufumi

    2017-11-01

    Recent observation of collective-flow-like behaviours in small colliding systems attracts significant theoretical and experimental interests. In large colliding systems, large collective flow has been interpreted as manifestation of almost-perfect fluidity of the quark gluon plasma (QGP). So it is quite intriguing to explore how small the QGP can be as a fluid. Multiplicity fluctuations play a crucial role in centrality definition of the events in small colliding systems since the fluctuations are, in general, more important as the system size is getting smaller. To consider the correct multiplicity fluctuations, we employ PYTHIA which naturally describes multiplicity distribution in p+p collisions. We superpose p+p collisions by taking into account the number of participants and that of binary collisions from Monte-Carlo version of Glauber model and evaluate initial entropy density distributions which contain not only multiplicity fluctuations but also fluctuations of longitudinal profiles. Solving hydrodynamic equations followed by the hadronic afterburner, we calculate transverse momentum spectra, elliptic and triangular flow parameters in p+Au, d+Au and 3He+Au collisions at the RHIC energy and p+Pb collisions at the LHC energy. Although a large fraction of final anisotropic flow parameters comes from the fluid-dynamical stage, the effects of hadronic rescatterings turn out to be also important as well in understanding of the flow data in small colliding systems.

  2. A digital local studies collection

    Simona Resman

    2005-01-01

    Full Text Available Local studies and local studies departments reflect the entire spectrum of knowledge within the local community. Transition to the new digital environment means just continuing the basic functions of local studies collections: acquisition, cataloguing and preservation of materials in different formats on different media. The background of each digital library is the technical architecture of system that enables interaction between the user and the library, saving digital material and building a platform for searching and indexing digital objects. Using advanced ICT requests from librarians, designers of digital local studies collections a reflection about traditional roles. A digital local studies collection with new technology enlarges local boarders, local contents become more and more interesting for a wider sphere of people. In collecting of local materials a collaboration with archives and museums, with academic community, with community groups and with individuals comes in forefront. Digital local studies collections with their contents support local diversity, lifelong learning and social inclusion. The crucial elements of a digital local studies collection are attractive local contents with fast and simple access from one place – a portal. In the digital age public libraries become managers of knowledge also by establishing digital local studies collections.

  3. The Atlas of Chinese World Wide Web Ecosystem Shaped by the Collective Attention Flows.

    Lou, Xiaodan; Li, Yong; Gu, Weiwei; Zhang, Jiang

    2016-01-01

    The web can be regarded as an ecosystem of digital resources connected and shaped by collective successive behaviors of users. Knowing how people allocate limited attention on different resources is of great importance. To answer this, we embed the most popular Chinese web sites into a high dimensional Euclidean space based on the open flow network model of a large number of Chinese users' collective attention flows, which both considers the connection topology of hyperlinks between the sites and the collective behaviors of the users. With these tools, we rank the web sites and compare their centralities based on flow distances with other metrics. We also study the patterns of attention flow allocation, and find that a large number of web sites concentrate on the central area of the embedding space, and only a small fraction of web sites disperse in the periphery. The entire embedding space can be separated into 3 regions(core, interim, and periphery). The sites in the core (1%) occupy a majority of the attention flows (40%), and the sites (34%) in the interim attract 40%, whereas other sites (65%) only take 20% flows. What's more, we clustered the web sites into 4 groups according to their positions in the space, and found that similar web sites in contents and topics are grouped together. In short, by incorporating the open flow network model, we can clearly see how collective attention allocates and flows on different web sites, and how web sites connected each other.

  4. The Atlas of Chinese World Wide Web Ecosystem Shaped by the Collective Attention Flows

    Lou, Xiaodan; Li, Yong; Gu, Weiwei; Zhang, Jiang

    2016-01-01

    The web can be regarded as an ecosystem of digital resources connected and shaped by collective successive behaviors of users. Knowing how people allocate limited attention on different resources is of great importance. To answer this, we embed the most popular Chinese web sites into a high dimensional Euclidean space based on the open flow network model of a large number of Chinese users’ collective attention flows, which both considers the connection topology of hyperlinks between the sites and the collective behaviors of the users. With these tools, we rank the web sites and compare their centralities based on flow distances with other metrics. We also study the patterns of attention flow allocation, and find that a large number of web sites concentrate on the central area of the embedding space, and only a small fraction of web sites disperse in the periphery. The entire embedding space can be separated into 3 regions(core, interim, and periphery). The sites in the core (1%) occupy a majority of the attention flows (40%), and the sites (34%) in the interim attract 40%, whereas other sites (65%) only take 20% flows. What’s more, we clustered the web sites into 4 groups according to their positions in the space, and found that similar web sites in contents and topics are grouped together. In short, by incorporating the open flow network model, we can clearly see how collective attention allocates and flows on different web sites, and how web sites connected each other. PMID:27812133

  5. Study of collective flow of inclusive muons in p–Pb collisions at $\\sqrt{s_{\\rm NN}}$ = 8.16 TeV with ALICE

    Chetcuti, Wayne Jordan

    2017-01-01

    This work focuses on the results obtained from the ALICE muon spectrometer for the measurement of the elliptic flow of muons at forward rapidity in p–Pb collisions at 8.16 TeV. The muon triggered data sample that was used, gave the minimum-bias data sample, as well as sufficient statistics at intermediate and high $p_T$ . The correction for the non-uniform detector appearance was performed and the Generic Q-cumulant method for 2- and 4-particle correlations was applied to get the elliptic flow of inclusive muons. From the results of the elliptic flow, it was suggested that the observed hydrodynamic-like particle correlations at high multiplicity in small systems may come out from the same underlying physics mechanisms as that in heavy-ion collisions.

  6. Flow speed measurement using two-point collective light scattering

    Heinemeier, N.P.

    1998-09-01

    Measurements of turbulence in plasmas and fluids using the technique of collective light scattering have always been plagued by very poor spatial resolution. In 1994, a novel two-point collective light scattering system for the measurement of transport in a fusion plasma was proposed. This diagnostic method was design for a great improvement of the spatial resolution, without sacrificing accuracy in the velocity measurement. The system was installed at the W7-AS steallartor in Garching, Germany, in 1996, and has been operating since. This master thesis is an investigation of the possible application of this new method to the measurement of flow speeds in normal fluids, in particular air, although the results presented in this work have significance for the plasma measurements as well. The main goal of the project was the experimental verification of previous theoretical predictions. However, the theoretical considerations presented in the thesis show that the method can only be hoped to work for flows that are almost laminar and shearless, which makes it of very small practical interest. Furthermore, this result also implies that the diagnostic at W7-AS cannot be expected to give the results originally hoped for. (au)

  7. Flow speed measurement using two-point collective light scattering

    Heinemeier, N.P

    1998-09-01

    Measurements of turbulence in plasmas and fluids using the technique of collective light scattering have always been plagued by very poor spatial resolution. In 1994, a novel two-point collective light scattering system for the measurement of transport in a fusion plasma was proposed. This diagnostic method was design for a great improvement of the spatial resolution, without sacrificing accuracy in the velocity measurement. The system was installed at the W7-AS steallartor in Garching, Germany, in 1996, and has been operating since. This master thesis is an investigation of the possible application of this new method to the measurement of flow speeds in normal fluids, in particular air, although the results presented in this work have significance for the plasma measurements as well. The main goal of the project was the experimental verification of previous theoretical predictions. However, the theoretical considerations presented in the thesis show that the method can only be hoped to work for flows that are almost laminar and shearless, which makes it of very small practical interest. Furthermore, this result also implies that the diagnostic at W7-AS cannot be expected to give the results originally hoped for. (au) 1 tab., 51 ills., 29 refs.

  8. Semihard scattering unraveled from collective flow at the SPS

    Bielcikova, J; Appelshäuser, H; Baur, R; Braun-Munzinger, P; Cherlin, A; Drees, A; Esumi, S I; Filimonov, K; Fraenkel, Zeev; Fuchs, C; Glässel, P; Hering, G; Lenkeit, B C; Marin, A; Messer, F; Messer, M; Milosevic, J; Miskowiec, D; Nix, O; Panebratsev, Yu A; Petracek, V; Pfeiffer, A; Rak, J; Ravinovich, I; Razin, S; Rehak, P; Sako, H; Saveljic, N; Schmitz, W; Shimansky, S S; Socol, E; Specht, H J; Stachel, J; Tilsner, H; Tserruya, Itzhak; Voigt, C; Voloshin, S; Weber, C; Wessels, J P; Wurm, J P; Yurevich, V

    2005-01-01

    A study of elliptic flow and two-particle azimuthal correlations of charged particles (0.5

    flow (nu/sub 2/) rises linearly with p/sub T/ to a value of about 10% at 2 GeV/c. Beyond p/sub T/approx.1.5 GeV/c, the slope decreases and possibly indicates a nu/sub 2/ saturation at high pGeV/c exceed the nu/sub 2/ values by about 60% in semicentral collisions. This non-flow component is attributed to near-side and away-side jetlike correlations. While the near-side peak remains constant with centrality 0.230.03 rad, as expected for fragmentation, the away- side peak experiences broadening and disappears in central collisions.

  9. Ion collection by probing objects in flowing magnetized plasmas

    Kyu-Sun, Chung.

    1989-04-01

    A new one-dimensional collisionless kinetic model is developed for the flow of ions to probing structures in drifting plasmas. The cross-field flow into the presheath is modelled by accounting consistently for particle exchange between the collection flux tube and the outer plasma. Numerical solutions of the self-consistent plasma/sheath equations are obtained with arbitrary external ion temperature and parallel plasma flow velocity. Results are presented of the spatial dependence of the ion distribution function as well as its moments (density, particle flux, temperature, and power flux). The ion current to the probe is obtained and the ratio of the upstream to downstream currents is found to be well represented by the form R = exp[Ku d ], where K = 1.66 for T i = T e and u d is the drift velocity in units of (T e /m i ) 1/2 . The results agree well with comparable recent fluid calculations but show substantial deviations from other models which ignore particle exchange out of the presheath. No evidence is found of the formation of shocks in the downstream wake, contrary to the implications of some fluid theories. We have also extended the previous kinetic model by generalizing cross-field transport and adding ionization to the source of the Boltzmann equation along the presheath. Ion sheath current density and ratio(R) of upstream to downstream current are obtained as a function of plasma drift velocity, equivalent viscosity, ion temperature, and ionization rate. Constants(K) in the form R = exp[Ku d ] are obtained in terms of viscosity, ion temperature, and ionization rate. The effect of an electrical bias applied to the object on the presheath characteristics is discussed

  10. Inverted annular flow experimental study

    De Jarlais, G.; Ishii, M.

    1985-04-01

    Steady-state inverted annular flow of Freon 113 in up flow was established in a transparent test section. Using a special inlet configuration consisting of long aspect-ratio liquid nozzles coaxially centered within a heated quartz tube, idealized inverted annular flow initial geometry (cylindrical liquid core surrounded by coaxial annulus of gas) could be established. Inlet liquid and gas flowrates, liquid subcooling, and gas density (using various gas species) were measured and varied systematically. The hydrodynamic behavior of the liquid core, and the subsequent downstream break-up of this core into slugs, ligaments and/or droplets of various sizes, was observed. In general, for low inlet liquid velocities it was observed that after the initial formation of roll waves on the liquid core surface, an agitated region of high surface area, with attendant high momentum and energy transfers, occurs. This agitated region appears to propagate downsteam in a quasi-periodic pattern. Increased inlet liquid flow rates, and high gas annulus flow rates tend to diminish the significance of this agitated region. Observed inverted annular flow (and subsequent downstream flow pattern) hydrodynamic behavior is reported, and comparisons are drawn to data generated by previous experimenters studying post-CHF flow

  11. Correlative degree and collective side ward flow of final state particles in high energy heavy ion collisions

    Zhang Weigang

    1999-01-01

    A concept of correlative degree is proposed. Using the method of particle-group correlation's function, the effects of the particles with different correlative degrees on collective side ward flow are studied for 1.2A GeV Ar + Bal 2 collisions at the Bevalac stream chamber. The studies indicate that correlative degree is an important parameter on describing collective side ward flow properties. The minority of correlative particles (or fragments) with larger correlative degrees can produce the effect arising from the collective side ward flow, but the effect arising from high-order collective flow correlations can not be dominated by these minority of particles (or fragments). It is results from the collective contribution of the majority of collective particles (or fragments) with various correlative degrees

  12. Collective flow in central Ca + Ca and Nb + Nb collisions

    Fai, G.; Csernai, L.P.; Kapusta, J.I.

    1986-01-01

    Questions related to the entropy, equation of state and collective flow of nuclear matter are important to the authors understanding of high energy nuclear collisions. Completion of the analysis of exclusive measurements on central Ca + Ca and Nb + Nb collisions triggered renewed interest in these problems. In order to address the results of exclusive measurements, however, the complex multifragment final states of high energy nuclear collisions need to be incorporated in a theoretical description. The microcanonical event generator model provides statistically generated complete events that can be compared to the exclusive data on an event-by-event basis. To describe the disassembly of hot nuclear matter the model uses an approximate scheme in which the available final states are populated according to their microcanonical weight in phase space. This statistical description is front-ended with simple geometric ideas to divide the collision system into subsystems and with a prescription to share energy and momentum among the subsystems. Any physical quantity of interest is in principle calculable in the model if sufficient statistics is accumulated

  13. Change the Collective Behaviors of Colloidal Motors by Tuning Electrohydrodynamic Flow at the Subparticle Level.

    Yang, Xingfu; Wu, Ning

    2018-01-23

    As demonstrated in biological systems, breaking the symmetry of surrounding hydrodynamic flow is the key to achieve autonomous locomotion of microscopic objects. In recent years, a variety of synthetic motors have been developed based on different propulsion mechanisms. Most work, however, focuses on the propulsion of individual motors. Here, we study the collective behaviors of colloidal dimers actuated by a perpendicularly applied AC electric field, which controls the electrohydrodynamic flow at subparticle levels. Although these motors experience strong dipolar repulsion from each other and are highly active, surprisingly, they assemble into a family of stable planar clusters with handedness. We show that this type of unusual structure arises from the contractile hydrodynamic flow around small lobes but extensile flow around the large lobes. We further reveal that the collective behavior, assembled structure, and assembly dynamics of these motors all depend on the specific directions of electrohydrodynamic flow surrounding each lobe of the dimers. By fine-tuning the surface charge asymmetry on particles and salt concentration in solution, we demonstrate the ability to control their collective behaviors on demand. This novel type of active assembly via hydrodynamic interactions has the potential to grow monodisperse clusters in a self-limiting fashion. The underlying concept revealed in this work should also apply to other types of active and asymmetric particles.

  14. Effect of isospin degree of freedom on the counterbalancing of collective transverse in-plane flow

    Sood, Aman D.

    2011-01-01

    Isospin degrees of freedom play an important role in heavy-ion collisions (HIC) through both nn collisions and equation of state (EOS). To access the EOS and its isospin dependence it is important to describe observables which are sensitive to isospin degree of freedom. Collective transverse in-plane flow as well as its disappearance has been found to be one such observable where it is well known that there exists a particular incident energy called as balance energy (E bal ) at which in-plane transverse flow disappears. The disappearance of flow occurs due to the counterbalancing of attractive and repulsive interactions. In literature the isospin dependence of collective flow as well as its disappearance has been explained to be a result of complex interplay between various reaction mechanisms, such as nn collisions, symmetry energy, surface properties of colliding nuclei and Coulomb repulsion. Here the aim was to understand the effect of above mentioned mechanisms on the counterbalancing of collective flow. The present study is carried out within the framework of IQMD model

  15. Visualization study of flow in axial flow inducer.

    Lakshminarayana, B.

    1972-01-01

    A visualization study of the flow through a three ft dia model of a four bladed inducer, which is operated in air at a flow coefficient of 0.065, is reported in this paper. The flow near the blade surfaces, inside the rotating passages, downstream and upstream of the inducer is visualized by means of smoke, tufts, ammonia filament, and lampblack techniques. Flow is found to be highly three dimensional, with appreciable radial velocity throughout the entire passage. The secondary flows observed near the hub and annulus walls agree with qualitative predictions obtained from the inviscid secondary flow theory.

  16. Collective flow as a probe of heavy-ion reaction dynamics

    Awes, T.C.

    1997-01-01

    Collective flow of nuclear matter probes the dynamics of heavy-ion reactions and can provide information about the nuclear-matter equation of state. In particular, the incident energy dependences of collective flow may be a sensitive means to deduce the existence of a Quark Gluon Plasma phase in the equation of state. Collective flow measurements from 30 A MeV to 200 A GeV incident energies are briefly reviewed. Preliminary results on collective flow from the WA98 experiment at the CERN SPS are presented

  17. Collective Efficacy in Sports and Physical Activities: Perceived Emotional Synchrony and Shared Flow

    Zumeta, Larraitz N.; Oriol, Xavier; Telletxea, Saioa; Amutio, Alberto; Basabe, Nekane

    2016-01-01

    This cross-sectional study analyzes the relationship between collective efficacy and two psychosocial processes involved in collective sport-physical activities. It argues that in-group identification and fusion with the group will affect collective efficacy (CE). A sample of 276 university students answered different scales regarding their participation in collective physical and sport activities. Multiple-mediation analyses showed that shared flow and perceived emotional synchrony mediate the relationship between in-group identification and CE, whereas the relationship between identity fusion and CE was only mediated by perceived emotional synchrony. Results suggest that both psychosocial processes explain the positive effects of in-group identification and identity fusion with the group in collective efficacy. Specifically, the role of perceived emotional synchrony in explaining the positive effects of participation in collective sport-physical activities is underlined. In sum, this study highlights the utility of collective actions and social identities to explain the psychosocial processes related to collective efficacy in physical and sports activities. Finally, practical implications are discussed. PMID:26779077

  18. Collective efficacy in sports and physical activities: perceived emotional synchrony and shared flow

    Larraitz Nerea Zumeta

    2016-01-01

    Full Text Available This cross-sectional study analyzes the relationship between collective efficacy and two psychosocial processes involved in collective sport-physical activities. It argues that in-group identification and fusion with the group will affect collective efficacy (CE. A sample of 276 university students answered different scales regarding their participation in collective physical and sport activities. Multiple-mediation analyses showed that shared flow and perceived emotional synchrony mediate the relationship between in-group identification and CE, whereas the relationship between identity fusion and CE was only mediated by perceived emotional synchrony. Results suggest that both psychosocial processes explain the positive effects of in-group identification and identity fusion with the group in collective efficacy. Especially, the role of perceived emotional synchrony in explaining the positive effects of participation in collective sport-physical activities is underlined. In sum, this study remarks the utility of collective actions and social identities to explain the psychosocial processes related to collective efficacy in physical and sports activities. Finally, practical implications are discussed.

  19. Collective flow and azimuthal correlations in nucleus-nucleus collisions at the Bevalac

    Rai, G.

    1993-09-01

    The EOS experiment at the Bevalac has recently carried out exclusive event-by-event measurements of relativistic heavy ion collisions with a variety of projectile, target and beam energy combinations. The data was obtained using the EOS Time Projection Chamber. We present preliminary results on inclusive spectra, collective flow and azimuthal correlations obtained from a study of Au + Au reactions with beam energies covering 0.6 - 1.2 A GeV

  20. Collective dynamics of particles from viscous to turbulent flows

    2017-01-01

    The book surveys the state-of-the-art methods that are currently available to model and simulate the presence of rigid particles in a fluid flow. For particles that are very small relative to the characteristic flow scales and move without interaction with other particles, effective equations of motion for particle tracking are formulated and applied (e.g. in gas-solid flows). For larger particles, for particles in liquid-solid flows and for particles that interact with each other or possibly modify the overall flow detailed model are presented. Special attention is given to the description of the approximate force coupling method (FCM) as a more general treatment for small particles, and derivations in the context of low Reynolds numbers for the particle motion as well as application at finite Reynolds numbers are provided. Other topics discussed in the book are the relation to higher resolution immersed boundary methods, possible extensions to non-spherical particles and examples of applications of such met...

  1. INDRA-GSI: Collective flow from Fermi to relativistic energies

    Lukasik, J.; Trautmann, W.; Begemann-Blaich, M.L.; Bittiger, R.; Gourio, D.; Le Fevre, A.; Lynen, U.; Mueller, W.F.J.; Orth, H.; Sfienti, C.; Schwarz, C.; Turzo, K. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Auger, G.; Bouriquet, B.; Chbihi, A.; Frankland, J.D.; Hudan, S.; Lopez, O. [GANIL, CEA et IN2P3-CNRS, 14 - Caen (France); Borderie, B.; Galichet, E.; Lavaud, F.; Plagnol, E. [Paris-11 Univ., Institut de Physique Nucleaire, IN2P3-CNRS, 91 - Orsay (France); Bellaize, N.; Bocage, F.; Bougault, R.; Durand, D.; Hurst, B.; Steckmeyer, J.C.; Tamain, B.; Vient, E. [Caen Univ., LPC (IN2P3-CNRS/ENSI), 14 - Caen (France); Charvet, J.L.; Dayras, R.; Legrain, R.; Nalpas, L.; Volant, C. [CEA Saclay, Dept. d' Astrophysique, de Physique des Particules, de Physique Nucleaire et de l' Instrumentation Associee (DAPNIA/SPhN), 91- Gif sur Yvette (France); Guinet, D.; Lautesse, P. [Institut de Physique Nucleaire, IN2P3-CNRS et Universite, 69 - Villeurbanne (France); Rosato, E.; Vigilante, M. [INFN, Univ. Federico II, Dipartimento di Scienze Fisiche e Sezione, Napoli (Italy); Saija, A. [Universita and INFN I, Dipartimento di Fisica dell' , Catania (Italy); Trzcinski, A.; Zwieglinski, B. [A. Soltan Institute for Nuclear Studies, Warsaw (Poland); Lukasik, J. [H. Niewodniczanski Institute of Nuclear Physics, Krakow (Poland); Galichet, E. [Conservatoire National des Arts et Metiers, 75 - Paris (France)

    2003-07-01

    Directed flow for the {sup 197}Au + {sup 197}Au reactions at incident energies between 40 and 150 A*MeV has been measured using the 4{pi} multi-detector INDRA at the GSI facility. In particular, the bombarding energy at which the elliptic flow switches from in-plane to out-of-plane enhancement has been determined to be around 100 A*MeV in good agreement with the result obtained by the FOPI Collaboration. The new data allows also to extend the experimental excitation function of v{sub 2} to lower energies. (authors)

  2. INDRA-GSI: Collective flow from Fermi to relativistic energies

    Lukasik, J.; Trautmann, W.; Begemann-Blaich, M.L.; Bittiger, R.; Gourio, D.; Le Fevre, A.; Lynen, U.; Mueller, W.F.J.; Orth, H.; Sfienti, C.; Schwarz, C.; Turzo, K.; Auger, G.; Bouriquet, B.; Chbihi, A.; Frankland, J.D.; Hudan, S.; Lopez, O.; Borderie, B.; Galichet, E.; Lavaud, F.; Plagnol, E.; Bellaize, N.; Bocage, F.; Bougault, R.; Durand, D.; Hurst, B.; Steckmeyer, J.C.; Tamain, B.; Vient, E.; Charvet, J.L.; Dayras, R.; Legrain, R.; Nalpas, L.; Volant, C.; Guinet, D.; Lautesse, P.; Rosato, E.; Vigilante, M.; Saija, A.; Trzcinski, A.; Zwieglinski, B.; Lukasik, J.; Galichet, E.

    2003-01-01

    Directed flow for the 197 Au + 197 Au reactions at incident energies between 40 and 150 A*MeV has been measured using the 4π multi-detector INDRA at the GSI facility. In particular, the bombarding energy at which the elliptic flow switches from in-plane to out-of-plane enhancement has been determined to be around 100 A*MeV in good agreement with the result obtained by the FOPI Collaboration. The new data allows also to extend the experimental excitation function of v 2 to lower energies. (authors)

  3. Collective flow effects observed with the Plastic Ball

    Gustafsson, H.A.; Gutbrod, H.H.; Kolb, B.

    1984-01-01

    At the Bevalac, collisions of Ca + Ca and Nb + Nb at 400 MeV/nucleon have been studied with the Plastic Ball/Plastic Wall detector. The Plastic Ball covers the angular region between 10 0 and 160 0 . It consists of 815 detectors where each module is a ΔE-E telescope capable of identifying the hydrogen and helium isotopes and positive pions. The ΔE measurement is performed with a 4-mm thick CaF crystal and the E counter is a 36-cm long plastic scintillator. Both signals are read out by a single photomultiplier tube. Due to the different decay times of the two scintillators, ΔE and E information can be separated by gating two different ADC-s at different times. The positive pions are additionally identified by measuring the delayed decay. The Platic Wall, placed 6 m downstream from the target, covers the angular range from 0 0 to 10 0 and measures time of flight, energy loss and position of the reaction products. In addition, the information from the inner counters (0 0 to 2 0 ) is used to produce a trigger signal. Data show two different collection effects

  4. Measurements of multi-particle correlations and collective flow with the ATLAS detector

    Bold, Tomasz; The ATLAS collaboration

    2017-01-01

    The measurement of flow harmonics of charged particles from v_2 to v_7 in Pb+Pb collisions in the wide range of transverse momentum and pseudorapidity provides not only a way to study the initial state of the nuclear collisions and soft particle collective dynamics, but also provides insight into jet quenching via the measurement of flow harmonics at high transverse momenta. The longitudinal fluctuations of the v_n and event-plane angles Psi_n are also presented. The longitudinal flow decorrelations have contributions from v_n-magnitude fluctuations and event plane twist. A four-particle correlator is used to separate these two effects. Results show both effects have a linear dependence on pseudorapidity separation from v_2 to v_5, and show a small but measurable variation with collision energy. While collectivity is well established in collisions involving heavy nuclei, its evidence in pp collisions is less clear. In order to assess the collective nature of multi-particle production, the correlation measurem...

  5. Measurements of multi-particle correlations and collective flow with the ATLAS detector

    Bold, Tomasz; The ATLAS collaboration

    2017-01-01

    The measurement of flow harmonics of charged particles from $v_2$ to $v_7$ in Pb+Pb collisions in the wide range of transverse momentum and pseudorapidity provides not only a way to study the initial state of the nuclear collisions and soft particle collective dynamics, but also provides insight into jet quenching via the measurement of flow harmonics at high transverse momenta. The longitudinal fluctuations of the $v_n$ and event-plane angles $\\Psi_n$ are also presented. The longitudinal flow decorrelations have contributions from $v_n$-magnitude fluctuations and event plane twist. A four-particle correlator is used to separate these two effects. Results show both effects have a linear dependence on pseudorapidity separation from $v_2$ to $v_5$, and show a small but measurable variation with collision energy. While collectivity is well established in collisions involving heavy nuclei, its evidence in pp collisions is less clear. In order to assess the collective nature of multi-particle production, the corre...

  6. Collective flow in relativistic heavy-ion collisions

    A brief introduction is given to the field of collective flow, currently being investigated experimentally at the Relativistic Heavy-Ion Collider, Brookhaven National Laboratory. It is followed by an outline of the work that I have been doing in this field, in collaboration with Nicolas Borghini and Jean-Yves Ollitrault.

  7. INTERACTIONS OF FLOWING PLASMA WITH COLLECTING SPHERE/OBJECTS

    HUTCHINSON, IAN H.

    2013-10-31

    The proposer’s computational flowing plasma group, supported in part by NSF/DOE since 2006, has been enormously productive. It has published 22 journal articles, of which 3 are in Physical Review Letters; received a total of 330 citations, and made 5 invited and numerous contributed presentations at international conferences. In addition, other groups have published at least 3 papers [20-22] based upon results they have obtained from the SCEPTIC code, developed by the proposer. The codes developed for this subject are Particle In Cell (PIC) codes, representing the entire ion distribution function and its variation in space in the vicinity of an absorbing object.

  8. Ontogeny of flow-stimulated potassium secretion in rabbit cortical collecting duct: functional and molecular aspects.

    Woda, Craig B; Miyawaki, Nobuyuki; Ramalakshmi, Santhanam; Ramkumar, Mohan; Rojas, Raul; Zavilowitz, Beth; Kleyman, Thomas R; Satlin, Lisa M

    2003-10-01

    High urinary flow rates stimulate K secretion in the fully differentiated but not neonatal or weanling rabbit cortical collecting duct (CCD). Both small-conductance secretory K and high-conductance Ca2+/stretch-activated maxi-K channels have been identified in the apical membrane of the mature CCD by patch-clamp analysis. We reported that flow-stimulated net K secretion in the adult rabbit CCD is 1) blocked by TEA and charybdotoxin, inhibitors of intermediate- and high-conductance (maxi-K) Ca2+-activated K channels, and 2) associated with increases in net Na absorption and intracellular Ca2+ concentration ([Ca2+]i). The present study examined whether the absence of flow-stimulated K secretion early in life is due to a 1) limited flow-induced rise in net Na absorption and/or [Ca2+]i and/or 2) paucity of apical maxi-K channels. An approximately sixfold increase in tubular fluid flow rate in CCDs isolated from 4-wk-old rabbits and microperfused in vitro led to an increase in net Na absorption and [Ca2+]i, similar in magnitude to the response observed in 6-wk-old tubules, but it failed to generate an increase in net K secretion. By 5 wk of age, there was a small, but significant, flow-stimulated rise in net K secretion that increased further by 6 wk of life. Luminal perfusion with iberiotoxin blocked the flow stimulation of net K secretion in the adult CCD, confirming the identity of the maxi-K channel in this response. Maxi-K channel alpha-subunit message was consistently detected in single CCDs from animals >/=4 wk of age by RT-PCR. Indirect immunofluorescence microscopy using antibodies directed against the alpha-subunit revealed apical labeling of intercalated cells in cryosections from animals >/=5 wk of age; principal cell labeling was generally intracellular and punctate. We speculate that the postnatal appearance of flow-dependent K secretion is determined by the transcriptional/translational regulation of expression of maxi-K channels. Furthermore, our studies

  9. Local evolution of pyrethroid resistance offsets gene flow among Aedes aegypti collections in Yucatan State, Mexico.

    Saavedra-Rodriguez, Karla; Beaty, Meaghan; Lozano-Fuentes, Saul; Denham, Steven; Garcia-Rejon, Julian; Reyes-Solis, Guadalupe; Machain-Williams, Carlos; Loroño-Pino, Maria Alba; Flores-Suarez, Adriana; Ponce-Garcia, Gustavo; Beaty, Barry; Eisen, Lars; Black, William C

    2015-01-01

    The mosquito Aedes aegypti is the major vector of the four serotypes of dengue virus (DENV1-4). Previous studies have shown that Ae. aegypti in Mexico have a high effective migration rate and that gene flow occurs among populations that are up to 150 km apart. Since 2000, pyrethroids have been widely used for suppression of Ae. aegypti in cities in Mexico. In Yucatan State in particular, pyrethroids have been applied in and around dengue case households creating an opportunity for local selection and evolution of resistance. Herein, we test for evidence of local adaptation by comparing patterns of variation among 27 Ae. aegypti collections at 13 single nucleotide polymorphisms (SNPs): two in the voltage-gated sodium channel gene para known to confer knockdown resistance, three in detoxification genes previously associated with pyrethroid resistance, and eight in putatively neutral loci. The SNPs in para varied greatly in frequency among collections, whereas SNPs at the remaining 11 loci showed little variation supporting previous evidence for extensive local gene flow. Among Ae. aegypti in Yucatan State, Mexico, local adaptation to pyrethroids appears to offset the homogenizing effects of gene flow. © The American Society of Tropical Medicine and Hygiene.

  10. Collecting and Storing Data Flow Monitoring in Elasticsearch

    Hashim, Fatin Hazwani

    2014-01-01

    A very large amount of data is produced from the online data flow monitoring for the CMS data acquisition system. However, there are only a small portion of data is stored permanently in the relational database. This is because of the high cost needed while relying on the dedicated infrastructure as well as the issues in its performance itself. A new approach needs to be found in order to confront such a big volume of data known as “Big Data”. The Big Data [1] is the term given to the very large and complex data sets that cannot be handled by the traditional data processing application [2] in terms of capturing, storing, managing, and analyzing. The sheer size of the data [3] in CMS data acquisition system is one of the major challenges, and is the one of the most easily recognized. New technology need to be used as the alternative of the traditional databases initial evaluation to handle this problem as more data need to be stored permanently and can be easily retrieved. This report consists of the intro...

  11. Women's Studies Collections: A Checklist Evaluation

    Bolton, Brooke A.

    2009-01-01

    A checklist evaluation on thirty-seven Women's Studies programs conducted using the individual institutions' online public access catalogs (OPACs) is presented. Although Women's Studies collections are very difficult to build, an evaluation of existing programs shows that collections, for the most part, have managed substantial coverage of the…

  12. Transverse energy per charged particle in heavy-ion collisions: Role of collective flow

    Kumar Tiwari, Swatantra; Sahoo, Raghunath

    2018-03-01

    The ratio of (pseudo)rapidity density of transverse energy and the (pseudo)rapidity density of charged particles, which is a measure of the mean transverse energy per particle, is an important observable in high energy heavy-ion collisions. This ratio reveals information about the mechanism of particle production and the freeze-out criteria. Its collision energy and centrality dependence is almost similar to the chemical freeze-out temperature until top Relativistic Heavy-Ion Collider (RHIC) energy. The Large Hadron Collider (LHC) measurement at √{s_{NN}} = 2.76 TeV brings up new challenges towards understanding the phenomena like gluon saturation and role of collective flow, etc. being prevalent at high energies, which could contribute to the above observable. Statistical Hadron Gas Model (SHGM) with a static fireball approximation has been successful in describing both the centrality and energy dependence until top RHIC energies. However, the SHGM predictions for higher energies lie well below the LHC data. In order to understand this, we have incorporated collective flow in an excluded-volume SHGM (EV-SHGM). Our studies suggest that the collective flow plays an important role in describing E T/ N ch and it could be one of the possible parameters to explain the rise observed in E T/ N ch from RHIC to LHC energies. Predictions are made for E T/ N ch , participant pair normalized-transverse energy per unit rapidity and the Bjorken energy density for Pb+Pb collisions at √{s_{NN}} = 5.02 TeV at the Large Hadron Collider.

  13. Solution of weakly compressible isothermal flow in landfill gas collection networks

    Nec, Y [Thompson Rivers University, Kamloops, British Columbia (Canada); Huculak, G, E-mail: cranberryana@gmail.com, E-mail: greg@gnhconsulting.ca [GNH Consulting, Delta, British Columbia (Canada)

    2017-12-15

    Pipe networks collecting gas in sanitary landfills operate under the regime of a weakly compressible isothermal flow of ideal gas. The effect of compressibility has been traditionally neglected in this application in favour of simplicity, thereby creating a conceptual incongruity between the flow equations and thermodynamic equation of state. Here the flow is solved by generalisation of the classic Darcy–Weisbach equation for an incompressible steady flow in a pipe to an ordinary differential equation, permitting continuous variation of density, viscosity and related fluid parameters, as well as head loss or gain due to gravity, in isothermal flow. The differential equation is solved analytically in the case of ideal gas for a single edge in the network. Thereafter the solution is used in an algorithm developed to construct the flow equations automatically for a network characterised by an incidence matrix, and determine pressure distribution, flow rates and all associated parameters therein. (paper)

  14. Solution of weakly compressible isothermal flow in landfill gas collection networks

    Nec, Y.; Huculak, G.

    2017-12-01

    Pipe networks collecting gas in sanitary landfills operate under the regime of a weakly compressible isothermal flow of ideal gas. The effect of compressibility has been traditionally neglected in this application in favour of simplicity, thereby creating a conceptual incongruity between the flow equations and thermodynamic equation of state. Here the flow is solved by generalisation of the classic Darcy-Weisbach equation for an incompressible steady flow in a pipe to an ordinary differential equation, permitting continuous variation of density, viscosity and related fluid parameters, as well as head loss or gain due to gravity, in isothermal flow. The differential equation is solved analytically in the case of ideal gas for a single edge in the network. Thereafter the solution is used in an algorithm developed to construct the flow equations automatically for a network characterised by an incidence matrix, and determine pressure distribution, flow rates and all associated parameters therein.

  15. Solution of weakly compressible isothermal flow in landfill gas collection networks

    Nec, Y; Huculak, G

    2017-01-01

    Pipe networks collecting gas in sanitary landfills operate under the regime of a weakly compressible isothermal flow of ideal gas. The effect of compressibility has been traditionally neglected in this application in favour of simplicity, thereby creating a conceptual incongruity between the flow equations and thermodynamic equation of state. Here the flow is solved by generalisation of the classic Darcy–Weisbach equation for an incompressible steady flow in a pipe to an ordinary differential equation, permitting continuous variation of density, viscosity and related fluid parameters, as well as head loss or gain due to gravity, in isothermal flow. The differential equation is solved analytically in the case of ideal gas for a single edge in the network. Thereafter the solution is used in an algorithm developed to construct the flow equations automatically for a network characterised by an incidence matrix, and determine pressure distribution, flow rates and all associated parameters therein. (paper)

  16. Experimental study on low pressure flow instability

    Jiang Shengyao; Wu Xinxin; Wu Shaorong; Bo Jinhai; Zhang Youjie

    1997-05-01

    The experiment was performed on the test loop (HRTL-5), which simulates the geometry and system design of the 5 MW reactor. The flow behavior for a wide range of inlet subcooling, in which the flow undergoes from single phase to two phase, is described in a natural circulation system at low pressure (p = 0.1, 0.24 MPa). Several kinds of flow instability, e.g. subcooled boiling instability, subcooled boiling induced flashing instability, pure flashing instability as well as flashing coupled density wave instability and high frequency flow oscillation, are investigated. The mechanism of flashing and flashing concerned flow instability, which has never been studied well in this field, is especially interpreted. The experimental results show that, firstly, for a low pressure natural circulation system the two phase flow is unstable in most of inlet subcooling conditions, the two phase stable flow can only be reached at very low inlet subcooling; secondly, at high inlet subcooling the flow instability is dominated by subcooled boiling in the heated section, and at middle inlet subcooling is dominated by void flashing in the adiabatic long riser; thirdly, in two phase stable flow region the condition for boiling out of the core, namely, single phase flow in the heated section, two phase flow in the riser due to vapor flashing, can be realized. The experimental results are very important for the design and accident analysis of the vessel and swimming pool type natural circulation nuclear heating reactor. (7 refs., 10 figs., 1 tab.)

  17. Studying shocks in model astrophysical flows

    Chakrabarti, S.K.

    1989-01-01

    We briefly discuss some properties of the shocks in the existing models for quasi two-dimensional astrophysical flows. All of these models which allow the study of shock analytically have some unphysical characteristics due to inherent assumptions made. We propose a hybrid model for a thin flow which has fewer unpleasant features and is suitable for the study of shocks. (author). 5 refs

  18. Flow assurance studies for CO2 transport

    Veltin, J.; Belfroid, S.P.C.

    2013-01-01

    In order to compensate for the relative lack of experience of the CCTS community, Flow Assurance studies of new CO2 pipelines and networks are a very important step toward reliable operation. This report details a typical approach for Flow Assurance study of CO2 transport pipeline. Considerations to

  19. Negative elliptic flow of J/ψ's: A qualitative signature for charm collectivity at RHIC

    Krieg, D.; Bleicher, M.

    2009-01-01

    We discuss one of the most prominent features of the very recent preliminary elliptic flow data of J/ψ-mesons from the PHENIX Collaboration (PHENIX Collaboration (C. Silvestre), arXiv:0806.0475 [nucl-ex]). Even within the rather large error bars of the measured data a negative elliptic flow parameter (v 2 ) for J/ψ in the range of p T =0.5-2.5 GeV/c is visible. We argue that this negative elliptic flow at intermediate p T is a clear and qualitative signature for the collectivity of charm quarks produced in nucleus-nucleus reactions at RHIC. Within a parton recombination approach we show that a negative elliptic flow puts a lower limit on the collective transverse velocity of heavy quarks. The numerical value of the transverse flow velocity β T for charm quarks that is necessary to reproduce the data is β T (charm) ∝0.55-0.6c and therefore compatible with the flow of light quarks. (orig.) 3

  20. Negative elliptic flow of J/ψ's: A qualitative signature for charm collectivity at RHIC

    Krieg, D.; Bleicher, M.

    2009-01-01

    We discuss one of the most prominent features of the very recent preliminary elliptic flow data of J/ψ-mesons from the PHENIX Collaboration (PHENIX Collaboration (C. Silvestre), arXiv:0806.0475 [nucl-ex]). Even within the rather large error bars of the measured data a negative elliptic flow parameter (v2) for J/ψ in the range of p T = 0.5-2.5 GeV/ c is visible. We argue that this negative elliptic flow at intermediate pT is a clear and qualitative signature for the collectivity of charm quarks produced in nucleus-nucleus reactions at RHIC. Within a parton recombination approach we show that a negative elliptic flow puts a lower limit on the collective transverse velocity of heavy quarks. The numerical value of the transverse flow velocity βT^{} for charm quarks that is necessary to reproduce the data is βT^{}( charm) ˜ 0.55-0.6 c and therefore compatible with the flow of light quarks.

  1. Experimental study of collective processes in REB

    Bogdanov, L Yu; Sominskij, G G [St. Petersburg Technical University (Russian Federation)

    1997-12-31

    The role of collective processes at relativistic electron beam formation and transportation was studied experimentally by using new low-disturbing techniques. In particular, local mirror-like enhancements of the external magnetic field were introduced and their influence of the beam space charge oscillations was investigated. The amplitude-frequency characteristics of the space charge oscillations in different parts of the drift channel were measured by a set of high-frequency probes. On the base of the collected experimental data two possible mechanisms of development of the beam space charge oscillations are discussed: the two-stream instability and the diocotron instability. (J.U.). 2 figs., 4 refs.

  2. Numerical 3D flow simulation of attached cavitation structures at ultrasonic horn tips and statistical evaluation of flow aggressiveness via load collectives

    Mottyll, S.; Skoda, R.

    2015-12-01

    A compressible inviscid flow solver with barotropic cavitation model is applied to two different ultrasonic horn set-ups and compared to hydrophone, shadowgraphy as well as erosion test data. The statistical analysis of single collapse events in wall-adjacent flow regions allows the determination of the flow aggressiveness via load collectives (cumulative event rate vs collapse pressure), which show an exponential decrease in agreement to studies on hydrodynamic cavitation [1]. A post-processing projection of event rate and collapse pressure on a reference grid reduces the grid dependency significantly. In order to evaluate the erosion-sensitive areas a statistical analysis of transient wall loads is utilised. Predicted erosion sensitive areas as well as temporal pressure and vapour volume evolution are in good agreement to the experimental data.

  3. Contribution to the study of recirculating flows

    Grand, Dominique

    1975-01-01

    The technology of the integrated primary circuit of French LMFBR type reactors involves many difficulties relating to heat transfer and hydraulics of the sodium masses inside the reactor. The work reported was a basic research supporting said reactor type development. Recirculating flows were studied inside a rectangular cavity, in the presence of body forces. Results given were obtained from numerical simulation, experimental investigation and a formal theoretical analysis. Solutions were obtained using the numerical integration of the conservation equation for a planar isothermal laminar flow driven by a mobile wall. The turbulent flow was experimentally investigated, the fluid being then driven through a mixing layer in common with a channel flow. Local velocity measurements in isothermal flow were effected using a laser-anemometer. In the occurrence of heat transfer, the temperature field only was scanned; complementary data were also obtained from color Schlieren vizualisation. A theoretical study of the flow was done at high Reynolds number. The flow inside the cavity was then separated in two parts: an external part (the non-viscous core) located at the center of the cavity and an internal part, the shear region, about the walls. An inclusive solution connecting both parts was developed in the framework of the laminar flow; results obtained are in good agreement with the numerical data. (author) [fr

  4. To flow or not to flow : a study of elliptic flow and nonflow in proton-proton collisions in ALICE

    van der Kolk, N.

    2012-01-01

    The standard model of particle physics describes all known elementary particles and the forces between them. The strong force, which binds quarks inside hadrons and nucleons inside nuclei, is described by the theory of Quantum Chromodynamics. This theory predicts a new state of matter at extreme temperatures and densities: the Quark Gluon plasma. The ALICE experiment at the Large Hadron Collider near Geneva was build to study this QGP by looking at collisions of the most heavy stable ions: lead (Pb) ions. In such collisions one hopes to achieve sufficient energy density for the creation of a QGP. One of the signatures of QGP formation in high energy heavy ion collisions is the presence of collective behaviour in the system formed during the collision. This collectivity manifests itself in a common velocity in all produced particles: a collective flow. The most dominant contribution to collective flow is elliptic flow, which originates from the anisotropic overlap region of the two nuclei in non-central collisions and is visible in the azimuthal distribution of the produced particles. Elliptic flow is related to the equation of state of the system and its degree of thermalisation. The analysis of elliptic flow is complicated by the presence of correlations between particles from other sources, summarised in the term nonflow. Several analysis methods have become available over the years and have been implemented for elliptic flow analysis within the ALICE computing framework. These methods have different sensitivities to these nonflow correlations. Because the centre of mass energy at the LHC is so high, predictions have been made of collective behaviour even in proton-proton collisions. These predictions are very divers and give values between 0 and 0.2 for elliptic flow using different models. To constrain these predictions proton-proton data, recorded with the ALICE experiment at the LHC in the 2010 7 TeV proton-proton run, was studied. In proton-proton collisions

  5. Collective flow in 158AGeV Pb+Pb collisions

    Nishimura, S

    1998-01-01

    Anisotropic transverse flow has been studied with a magnetic spectrometer at mid-rapidity and the Plastic Ball detector at target rapidity in the WA98 experiment. Our preliminary results show the existence of directed and elliptic flow in semi-central Pb+Pb collisions. The magnitude of the directed

  6. A local studies collection: unexploited possibilities?

    Silva Novljan

    2005-01-01

    Full Text Available Public libraries have traditionally carried out the local history activities with the main emphasis on the collection and preservation of local studies material in order to meet the educational and research needs, whereas the significance of the local studies material for the everyday needs of different groups of citizens has not been emphasized so much. More than a decade ago, the document adopted by the National Council for Librarianship should have encouraged the librarians to modernize their work based on the market policy and to develop local studies collections in all libraries. By an analysis of the selected published articles and the collected data, the author states that librarians strived to improve the situation at all times but they have not achieved the goals. They will continue to follow this objective, but due to the new Act of Librarianship, now they can expect more help from the state and from the regional libraries, and also from the new technology. In author’s opinion, the help itself will not be sufficient if the market power of the local history material is not used, and if this material will not be brought closer to different target groups and individuals. Appropriate services should be provided inside and outside of their environment, and thus the diversity of the purposes of local studies material will be realized. A detailed definition of the benefits of the use of local studies material proposed by the author, provides a useful starting-point to encourage the use of local studies material and services, which can strengthen the satisfaction among the citizens and the reputation of the library in its environment.

  7. - GEONET - A Realization of an Automated Data Flow for Data Collecting, Processing, Storing, and Retrieving

    Friedsam, Horst; Pushor, Robert; Ruland, Robert; SLAC

    2005-01-01

    GEONET is a database system developed at the Stanford Linear Accelerator Center for the alignment of the Stanford Linear Collider. It features an automated data flow, ranging from data collection using HP110 handheld computers to processing, storing and retrieving data and finally to adjusted coordinates. This paper gives a brief introduction to the SLC project and the applied survey methods. It emphasizes the hardware and software implementation of GEONET using a network of IBM PC/XT's

  8. Energy dependence of collective flow of neutrons and charged particles in 197Au+197Au collisions

    Blaich, T.; Freiesleben, H.; Holzmann, R.; Keller, J.G.; Prokopowicz, W.; Schuetter, C.; Wajda, E.; Zude, E.

    1994-01-01

    Our contribution focusses on one particular aspect of collective flow of nuclear matter: the so-called ''squeeze-out'', i.e. the preferential emission of mid-rapidity particles perpendicular to the reaction plane. The data were taken for the system 197 Au + 197 Au at 400, 600 and 800 MeV/u. We cover two topics, the comparison of neutrons and protons, and the bombarding energy dependence of the neutrons' squeeze-out. (orig.)

  9. A realization of an automated data flow for data collecting, processing, storing and retrieving

    Friedsam, H.; Pushor, R.; Ruland, R.

    1986-11-01

    GEONET is a database system developed at the Stanford Linear Accelerator Center for the alignment of the Stanford Linear Collider. It features an automated data flow, ranging from data collection using HP110 handheld computers to processing, storing and retrieving data and finally to adjusted coordinates. This paper gives a brief introduction to the SLC project and the applied survey methods. It emphasizes the hardware and software implementation of GEONET using a network of IBM PC/XT's. 14 refs., 4 figs

  10. Influence of the nuclear symmetry energy on the collective flows of charged pions

    Gao, Yuan; Yong, Gao-Chan; Zhang, Lei; Zuo, Wei

    2018-01-01

    Based on the isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, we studied charged pion transverse and elliptic flows in semicentral 197Au+197Au collisions at 600 MeV/nucleon. It is found that π+-π- differential transverse flow and the difference of π+ and π- transverse flows almost show no effects of the symmetry energy. Their corresponding elliptic flows are largely affected by the symmetry energy, especially at high transverse momenta. The isospin-dependent pion elliptic flow at high transverse momenta thus provides a promising way to probe the high-density behavior of the symmetry energy in heavy-ion collisions at the Facility for Antiproton and Ion Research (FAIR) at GSI, Darmstadt or at the Cooling Storage Ring (CSR) at HIRFL, Lanzhou.

  11. Study in flow rig by using radiotracer

    Widatalla, R. K.

    2012-06-01

    Application of radioisotope technology have proved itself to be effective techniques for troubleshooting and optimizing industrial process in petrochemical industry In this study gamma scanning technique has been employed for better understanding of malfunctions by using the flow rig system. The scanning were carried out using 9 9mT C gamma radiation source with activity of 1 mCi and quantity of 5 ml to measure the flow rate for the water flow rig The experiment was repeated by reducing the data interval time to get more precise result. The investigations were also carried out using 5 ml of 9 9mT C with activity of 0.3 mCi for measuring the Residence Time Distribution (RTD) inside the flow rig tank which enables calculating the effective volume for the operating tank and its dead volume. The results proved that the technique is sensitive, reliable and can be adopted to investigate industrial reactors. (Author)

  12. Radioactive and industrial waste water collection system study, Phase I

    1993-01-01

    Phase I of the Radioactive Liquid Waste (RLW) Collection System Study has been completed, and the deliverables for this portion of the study are enclosed. The deliverables include: The Work Break-down Structure (WBS) for Phase II; The Annotated Outline for the Collection Study Report; The Process Flow Diagrams (PFD) of the RLW collection system based on current literature and knowledge; The Configuration database; The Reference Index, listing all currently held documents of the RLW collection system; The Reference Drawing Index listing all currently held, potentially applicable, drawings reviewed during the PFD development; The Regulation Identification Document for RCRA and CWA; The Regulation Database for RCRA and CWA; The Regulation Review Log, including statements justifying the non-applicability of certain regulations; Regulation Library, including the photocopied regulations with highlighted text for RCRA and CWA; The summary of RTG's waste water treatment plant design experience and associated regulations on which RTG based the design of these treatment facilities; TA-50 Influent Database; Radioactive Liquid Waste Stream Characterization Database

  13. Experimental study of the influence of flow passage subtle variation on mixed-flow pump performance

    Bing, Hao; Cao, Shuliang

    2014-05-01

    In the mixed-flow pump design, the shape of the flow passage can directly affect the flow capacity and the internal flow, thus influencing hydraulic performance, cavitation performance and operation stability of the mixed-flow pump. However, there is currently a lack of experimental research on the influence mechanism. Therefore, in order to analyze the effects of subtle variations of the flow passage on the mixed-flow pump performance, the frustum cone surface of the end part of inlet contraction flow passage of the mixed-flow pump is processed into a cylindrical surface and a test rig is built to carry out the hydraulic performance experiment. In this experiment, parameters, such as the head, the efficiency, and the shaft power, are measured, and the pressure fluctuation and the noise signal are also collected. The research results suggest that after processing the inlet flow passage, the head of the mixed-flow pump significantly goes down; the best efficiency of the mixed-flow pump drops by approximately 1.5%, the efficiency decreases more significantly under the large flow rate; the shaft power slightly increases under the large flow rate, slightly decreases under the small flow rate. In addition, the pressure fluctuation amplitudes on both the impeller inlet and the diffuser outlet increase significantly with more drastic pressure fluctuations and significantly lower stability of the internal flow of the mixed-flow pump. At the same time, the noise dramatically increases. Overall speaking, the subtle variation of the inlet flow passage leads to a significant change of the mixed-flow pump performance, thus suggesting a special attention to the optimization of flow passage. This paper investigates the influence of the flow passage variation on the mixed-flow pump performance by experiment, which will benefit the optimal design of the flow passage of the mixed-flow pump.

  14. Effects of solar collecting area and water flow rate on the performance of a sand bed solar collector

    Maganhar, A.L.; Memon, A.H.; Panhwar, M.I.

    2005-01-01

    The often discussed renewable sources of energy have been great interest to energy researchers and planners for quite some time. The primary of renewing all sources of energy is the sun. There have been two main problems not yet fully resolved. One is the large scale production of energy and other is the cost factor. In the present study, the cost factor is under consideration. In this regard a non-conventional solar collector using indigenous material (pit sand) as solar absorber is designed and manufactured. This paper presents the results of an investigation of the effect of solar collecting area and water flow rate on the performance of a pit sand bed solar collector especially in terms of rise in water temperature. Three pit sand solar collectors of area 1m/sup 2/ each were connected in series to enhance the collecting area and the system was tested for different flow rates. Experimental results proved that there was increase in water temperature with increase in solar collecting area an decreases in water temperature with increase in flow rate. (author)

  15. The study of the components of matter collective flow in the collisions of {sup 64} Zn on {sup 58} Ni at 35 to 79 MeV/u; Etude des composantes de l`ecoulement collectif de matiere dans les collisions {sup 64} Zn sur {sup 58} Ni de 35 a 79 MeV/u

    Popescu, R [Caen Univ., 14 (France). Lab. de Physique Corpusculaire

    1995-06-01

    In a nucleus-nucleus collision the collective motion of matter, emitted from the overlapping region, give information on the properties of nuclear matter out-of-equilibrium. The characteristics of this motion have been studied on the {sup 64} Zn on {sup 58} Ni system up to 79 MeV per nucleon, using the flow parameter and the azimuthal distributions. We studied the evolution of those quantities with the incident energy, the impact parameter and the charge of particle. The experiment has been done at GANIL using the multidetectors of light particles and fragments, Mur and Tonneau. For estimating the impact parameter, two global variables have been used: the average parallel velocity and the total perpendicular momentum. For determining the reaction plane two methods have been used: the transverse momentum analysis and the azimuthal correlation method. The results are not sensitive to the global variable or method. The measured values revealed the inversion of the direction of sideward flow. The energy of vanishing flow ranges from 55 to 75 MeV per nucleon when the impact parameter increases from 1 to 6 fm. In the same way, the aspect of the azimuthal distribution changes from in-plane to out-of-plane enhancement when the energy increases, providing with a new indication of change in the interaction dynamics. The energy of isotropic emission lies between 45 and 65 MeV per nucleon depending of the impact parameter. For alpha particles, the flow parameter and the azimuthal asymmetry are greater than for protons, due to a smaller thermal dispersion. A Landau-Vlasov model using a non-local Gogny force is able to reproduce the global characteristics experimentally observed (rapidity and transverse momentum distributions). The calculated flow and azimuthal asymmetry values reproduce the experimental ones for an incompressibility modulus near 230 MeV. The study of the dependence on nucleon-nucleon cross section in nuclear medium must be pursued. (author) 37 refs.

  16. Experimental study of unsteady thermally stratified flow

    Lee, Sang Jun; Chung, Myung Kyoon

    1985-01-01

    Unsteady thermally stratified flow caused by two-dimensional surface discharge of warm water into a oblong channel was investigated. Experimental study was focused on the rapidly developing thermal diffusion at small Richardson number. The basic objectives were to study the interfacial mixing between a flowing layer of warm water and an underlying body of cold water and to accumulate experimental data to test computational turbulence models. Mean velocity field measurements were carried out by using NMR-CT(Nuclear Magnetic Resonance-Computerized Tomography). It detects quantitative flow image of any desired section in any direction of flow in short time. Results show that at small Richardson number warm layer rapidly penetrates into the cold layer because of strong turbulent mixing and instability between the two layers. It is found that the transfer of heat across the interface is more vigorous than that of momentum. It is also proved that the NMR-CT technique is a very valuable tool to measure unsteady three dimensional flow field. (Author)

  17. Unsaturated flow characterization utilizing water content data collected within the capillary fringe

    Baehr, Arthur; Reilly, Timothy J.

    2014-01-01

    An analysis is presented to determine unsaturated zone hydraulic parameters based on detailed water content profiles, which can be readily acquired during hydrological investigations. Core samples taken through the unsaturated zone allow for the acquisition of gravimetrically determined water content data as a function of elevation at 3 inch intervals. This dense spacing of data provides several measurements of the water content within the capillary fringe, which are utilized to determine capillary pressure function parameters via least-squares calibration. The water content data collected above the capillary fringe are used to calculate dimensionless flow as a function of elevation providing a snapshot characterization of flow through the unsaturated zone. The water content at a flow stagnation point provides an in situ estimate of specific yield. In situ determinations of capillary pressure function parameters utilizing this method, together with particle-size distributions, can provide a valuable supplement to data libraries of unsaturated zone hydraulic parameters. The method is illustrated using data collected from plots within an agricultural research facility in Wisconsin.

  18. Extended RPA study of nuclear collective phenomena

    Drozdz, S.

    1987-01-01

    A fully microscopic study of nuclear collective phenomena is presented within the framework of an extended RPA which includes 1p-1h and 2p-2h excitations in a consistent way. This theory allows us to obtain a very realistic description of various excitation spectra. As a result, a strong evidence of correlation effects beyond mean-field theory emerges. The effective interaction used is a G-matrix derived from the meson-exchange potential. The extended theory introduces also additional correlations which screen the long-large part of the effective interaction. This effect significantly enhances the stability of the ground state against density fluctuations. In this connection a possible importance of relativistic effects is also discussed. 99 refs., 19 figs., 5 tabs. (author)

  19. Experimental studies of rotating exchange flow

    Rabe, B.; Smeed, D. A.; Dalziel, S. B.; Lane-Serff, G. F.

    2007-02-01

    Ocean basins are connected by straits and passages, geometrically limiting important heat and salt exchanges which in turn influence the global thermohaline circulation and climate. Such exchange can be modeled in an idealized way by taking into consideration the density-driven two-layer flow along a strait under the influence of rotation. We use a laboratory model of a lock exchange between two reservoirs of different density through a flat-bottom channel with a horizontal narrows, set up on two different platforms: a 1 m diameter turntable, where density interface position was measured by dye attenuation, and the 14 m diameter turntable at Coriolis/LEGI (Grenoble, France), where correlation imaging velocimetry, a particle imaging technique, allowed us to obtain for the first time detailed measurements of the velocity fields in these flows. The influence of rotation is studied by varying a parameter, Bu, a type of Burger number given by the ratio of the Rossby radius to the channel width at the narrows. In addition, a two-layer version of the Miami Isopycnic Coordinate Model (MICOM) is used, to study the cases with low Burger number. Results from experiments by Dalziel [1988. Two-layer hydraulics: maximal exchange flows. Ph.D. Thesis, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, see also people/sd103/papers/1988/Thesis_Dalziel.pdf>] are also included for comparison. Time-mean exchange fluxes for any Bu are in close agreement with the inviscid zero-potential vorticity theory of Dalziel [1990. Rotating two-layer sill flows. In: Pratt, L.J. (Ed.), The Physical Oceanography of Sea Straits. Kluwer Academic, Dordrecht, pp. 343-371] and Whitehead et al. [1974. Rotating hydraulics of strait and sill flows. Geophysical Fluid Dynamics 6, 101-125], who found that fluxes for Bu>1 mainly vary with channel width, similar to non-rotating flow, but for Bu1 a steady, two-layer flow was observed that persisted across the channel at the narrows

  20. [Statistical modeling studies of turbulent reacting flows

    Dwyer, H.A.

    1987-01-01

    This paper discusses the study of turbulent wall shear flows, and we feel that this problem is both more difficult and a better challenge for the new methods we are developing. Turbulent wall flows have a wide variety of length and time scales which interact with the transport processes to produce very large fluxes of mass, heat, and momentum. At the present time we have completed the first calculation of a wall diffusion flame, and we have begun a velocity PDF calculation for the flat plate boundary layer. A summary of the various activities is contained in this report

  1. Flow visualisation study of spiral flow in the aorta-renal bifurcation.

    Fulker, David; Javadzadegan, Ashkan; Li, Zuming; Barber, Tracie

    2017-10-01

    The aim of this study was to analyse the flow dynamics in an idealised model of the aorta-renal bifurcation using flow visualisation, with a particular focus on the effect of aorta-to-renal flow ratio and flow spirality. The recirculation length was longest when there was low flow in the renal artery and smaller in the presence of spiral flow. The results also indicate that patients without spiral flow or who have low flow in the renal artery due to the presence of stenosis may be susceptible to heightened development of atherosclerotic lesions.

  2. Radioisotope tracers in industrial flow studies

    Easey, J.F.

    1987-01-01

    The scope of radioisotope tracer work carried out by ANSTO has involved most sectors of Australian industry including iron and steel coal, chemical, petrochemical, natural gas, metallurgical, mineral, power generation, liquified air plant, as well as port authorities, water and sewerage instrumentalities, and environmental agencies. A major class of such studies concerns itself with flow and wear studies involving industrial equipment. Some examples are discussed which illustrate the utility of radioisotope tracer techniques in these applications

  3. Conjugate Heat Transfer Study in Hypersonic Flows

    Sahoo, Niranjan; Kulkarni, Vinayak; Peetala, Ravi Kumar

    2018-04-01

    Coupled and decoupled conjugate heat transfer (CHT) studies are carried out to imitate experimental studies for heat transfer measurement in hypersonic flow regime. The finite volume based solvers are used for analyzing the heat interaction between fluid and solid domains. Temperature and surface heat flux signals are predicted by both coupled and decoupled CHT analysis techniques for hypersonic Mach numbers. These two methodologies are also used to study the effect of different wall materials on surface parameters. Effectiveness of these CHT solvers has been verified for the inverse problem of wall heat flux recovery using various techniques reported in the literature. Both coupled and decoupled CHT techniques are seen to be equally useful for prediction of local temperature and heat flux signals prior to the experiments in hypersonic flows.

  4. VXIbus data collection system -- A design study

    Hacker, U.; Richter, B.; Weinert, A.; Arlt, R.; Lewis, W.; Swinhoe, M.

    1995-01-01

    The German support program has sponsored the work to investigate the VXIbus as integration platform for safeguards instrumentation. This paper will cover the analysis of the user requirements for a VXIbus based monitoring system for integrated safeguards -- primarily for reliable unattended in-field collection of large amounts of data. The goal is to develop a suitable system architecture. The design of the system makes use of the VXIbus standard as the selected hardware platform Based upon the requirement analysis and the overriding need for high reliability and robustness, a systematic investigation of different operating system options, as well as development and integration tools will be considered. For the software implementation cycle high and low level programming tools are required. The identification of the constraints for the programming platform and the tool selection will be presented. Both the strategic approach, the rules for analysis and design work as well as the executive components for the support of the implementation and production cycle are given. Here all the conditions for reliable, unattended and integrated safeguards monitoring systems will be addressed. The definition of the basic and advanced design principles are covered. The paper discusses the results of a study on a system produced to demonstrate a high data rate timer/counter application

  5. Experimental Study of Flow Through Carotid Aneurysms

    Masoomi, Faezeh; Mejia-Alvarez, Ricardo

    2017-11-01

    There is evidence that traditional endovascular techniques like coiling are not effective for treatment of wide-neck cerebral aneurysms. Flow Diverter Stents (FDS) have emerged as promising devices for treating complex aneurysms since they enable treatment of aneurysms that were considered untreatable before. Recent studies suggest a number of associated risks with FDS, including in-stent thrombosis, perianeurysmal edema, delayed hemorrhage, and perforator occlusions. Chong et al. simulated hemodynamic behavior using patient-specific data. From their study, it is possible to infer that the standard deviation of energy loss could be a good predictor for intervention success. The aim of this study is to investigate the flow in models of cerebral aneurysms before and after FDS insertion using PIV. These models will be based on actual clinical studies and will be fabricated with advanced additive manufacturing techniques. These data will then be used to explore flow parameters that could inform the likelihood of post-intervention aneurysm rupture, and help determine FDS designs that better suit any particular patient before its procedure.

  6. Study of two-phase foam flow

    Gurbanov, R S; Guliev, B B; Mekhtiev, K G; Kerimov, R G

    1970-01-01

    The objectives of this study were to determine characteristics of aqueous foam flow through porous media and to estimate the depth of foam penetration into a formation. Foam was generated by mixing air and 1% solution of surfactant PO-1. Foam density was maintained at 0.14 g/cc in all experiments. The foam was passed through sand columns (800 mm long x 30 mm diam) of permeabilities 26, 39, 80, 111, and 133 darcys. Flow rates were measured at various pressure drops and the relationship between system parameters was expressed analytically and graphically. From the data, distance of foam penetration into a formation as a function of pressure drop and permeability was calculated. The data indicate that under most conditions, foam will penetrate the formation to a negligible distance. This study indicates that when foam is used to remove sand from a well, a negligible loss of foam to the formation occurs.

  7. Experimental Study of Flow in a Bifurcation

    Fresconi, Frank; Prasad, Ajay

    2003-11-01

    An instability known as the Dean vortex occurs in curved pipes with a longitudinal pressure gradient. A similar effect is manifest in the flow in a converging or diverging bifurcation, such as those found in the human respiratory airways. The goal of this study is to characterize secondary flows in a bifurcation. Particle image velocimetry (PIV) and laser-induced fluorescence (LIF) experiments were performed in a clear, plastic model. Results show the strength and migration of secondary vortices. Primary velocity features are also presented along with dispersion patterns from dye visualization. Unsteadiness, associated with a hairpin vortex, was also found at higher Re. This work can be used to assess the dispersion of particles in the lung. Medical delivery systems and pollution effect studies would profit from such an understanding.

  8. Study of argon-oxygen flowing afterglow

    Mazánková, V.; Trunec, D.; Navrátil, Z.; Raud, J.; Krčma, F.

    2016-06-01

    The reaction kinetics in argon-oxygen flowing afterglow (post-discharge) was studied using NO titration and optical emission spectroscopy. The flowing DC post-discharge in argon-oxygen mixture was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 90 W. The O(3P) atom concentration was determined by NO titration at different places along the flow tube. The optical emission spectra were also measured along the flow tube. Argon spectral lines, oxygen lines at 777 nm and 844.6 nm and atmospheric A-band of {{\\text{O}}2} were identified in the spectra. Rotational temperature of {{\\text{O}}2} was determined from the oxygen atmospheric A-band and also the outer wall temperature of the flow tube was measured by a thermocouple and by an IR thermometer. A zero-dimensional kinetic model for the reactions in the afterglow was developed. This model allows the time dependencies of particle concentrations and of gas temperature to be calculated. The wall recombination probability for O(3P) atoms {γ\\text{O≤ft(\\text{P}\\right)}}=≤ft(1.63+/- 0.06\\right)× {{10}-3} and wall deactivation probability for {{\\text{O}}2} (b {{}1}Σ\\text{g}+ ) molecules {γ{{\\text{O}2}≤ft(\\text{b}\\right)}}=≤ft(1.7+/- 0.1\\right)× {{10}-3} were determined from the fit of model results to experimental data. Sensitivity analysis was applied for the analysis of kinetic model in order to reveal the most important reactions in the model. The calculated gas temperature increases in the afterglow and then decreases at later afterglow times after reaching the maximum. This behavior is in good agreement with the spatial rotational temperature dependence. A similar trend was also observed at outer wall temperature measurement.

  9. Asymmetry reversal of ion collection by mach probes in flowing unmagnetized plasmas

    Ko, E; Hershkowitz, N

    2006-01-01

    Measurements of ion current in flowing unmagnetized plasmas were performed with planar and spherical Mach probes in two different devices, one a dc multi-dipole plasma device for subsonic flow within a presheath region and the other a double plasma device for supersonic flow. Asymmetry reversal, which is higher ion current to the downstream side of the probe compared with the upstream side current, was observed for high probe bias compared with the electron temperature, relatively low ion drift velocity and Debye length comparable to probe radius. These data are in qualitative agreement with a recent numerical calculation by Hutchinson. As suggested by Hutchinson, it was found that the current ratio depended on the plasma parameters, especially for finite Debye length and high probe bias. Asymmetry reversal emphasizes the lack of validity of using the current ratio except for narrow parameter ranges. This study is the first experiment to demonstrate the non-intuitive phenomenon predicted by Hutchinson's numerical calculation

  10. Combustion and Mixing Studies in Compressible Flows.

    1996-09-01

    Astronautics 2 FULLER ET AL. dence times. It is a primary concern in hypersonic aircraft In fact, studies conducted by Povinelli et al.1 3 and Schetz...downstream. It was reasoned that pressure gradients in the swirling flow. Povinelli et al." such behavior should lead to increased turbulence levels...E.M., "Design and Calibration of Stagnation Tem- tion, 1968, pp. 1153-1162.11 .perature Probes for Use at High Supersonic Speeds and Elevated Povinelli

  11. Intracardiac flow patterns studied by cine MR flow imaging

    Underwood, S.R.; Firmin, D.N.; Klipstein, R.H.; Rees, R.S.O.; Longmore, D.B.

    1986-01-01

    Velocity mapping by means of cine-MR imaging allows accurate measurement of velocity and flow within the cardiovascular system. A cine display and color coding simplify interpretation. The author have used the technique in a variety of patients to illustrate its potential. Velocity mapping in coronary artery by pass grafts in six patients provided a measure of graft function. Coronary artery velocities were measured in three subjects. Flow was measured through defects in the atrial septum, the ventricular septum, and a Gerbode defect. Velocity was reduced distal to coarctation of the aorta and was increased at the level of a partial venous occlusion by thrombosis. In a patient with isomerism, velocity mapping in the central vessels aided interpretation. Cine-MR imaging velocity mapping combined with conventional imaging yields important functional information on the cardiovascular system

  12. Convection flow study within a horizontal fluid layer under the action of gas flow

    Kreta Aleksei

    2016-01-01

    Full Text Available Experimental investigation of convective processes within horizontal evaporating liquid layer under shear–stress of gas flow is presented. It is found the structures of the convection, which move in opposite direction relative to each other. First convective structure moves in reverse direction with the flow of gas, and the second convective structure moves towards the gas flow. Convection flow within the liquid layer is registered with help of PIV technique. Average evaporation flow rate of Ethanol liquid layer under Air gas flow is measured. Influence of the gas velocity, at a constant temperature of 20 °C, on the evaporation flow rate has been studied.

  13. 77 FR 28351 - Agency Information Collection Activities: Proposed Collection; Comment Request-Study of the Food...

    2012-05-14

    ... participants and eligible nonparticipants. In addition to primary data collection, the study will model effects... State-administered FDPIR programs, participating households will be selected for data collection. Data... operations and experiences of FDPIR participants and eligible nonparticipants. Site visit data collection...

  14. NATO Advanced Study Institute on Buoyant Convection in Geophysical Flows

    Fedorovich, E; Viegas, D; Wyngaard, J

    1998-01-01

    Studies of convection in geophysical flows constitute an advanced and rapidly developing area of research that is relevant to problems of the natural environment. During the last decade, significant progress has been achieved in the field as a result of both experimental studies and numerical modelling. This led to the principal revision of the widely held view on buoyancy-driven turbulent flows comprising an organised mean component with superimposed chaotic turbulence. An intermediate type of motion, represented by coherent structures, has been found to play a key role in geophysical boundary layers and in larger scale atmospheric and hydrospheric circulations driven by buoyant forcing. New aspects of the interaction between convective motions and rotation have recently been discovered and investigated. Extensive experimental data have also been collected on the role of convection in cloud dynamics and microphysics. New theoretical concepts and approaches have been outlined regarding scaling and parameteriz...

  15. Continuous-flow centrifugation to collect suspended sediment for chemical analysis

    Conn, Kathleen E.; Dinicola, Richard S.; Black, Robert W.; Cox, Stephen E.; Sheibley, Richard W.; Foreman, James R.; Senter, Craig A.; Peterson, Norman T.

    2016-12-22

    Recent advances in suspended-sediment monitoring tools and surrogate technologies have greatly improved the ability to quantify suspended-sediment concentrations and to estimate daily, seasonal, and annual suspended-sediment fluxes from rivers to coastal waters. However, little is known about the chemical composition of suspended sediment, and how it may vary spatially between water bodies and temporally within a single system owing to climate, seasonality, land use, and other natural and anthropogenic drivers. Many water-quality contaminants, such as organic and inorganic chemicals, nutrients, and pathogens, preferentially partition in sediment rather than water. Suspended sediment-bound chemical concentrations may be undetected during analysis of unfiltered water samples, owing to small water sample volumes and analytical limitations. Quantification of suspended sediment‑bound chemical concentrations is needed to improve estimates of total chemical concentrations, chemical fluxes, and exposure levels of aquatic organisms and humans in receiving environments. Despite these needs, few studies or monitoring programs measure the chemical composition of suspended sediment, largely owing to the difficulty in consistently obtaining samples of sufficient quality and quantity for laboratory analysis.A field protocol is described here utilizing continuous‑flow centrifugation for the collection of suspended sediment for chemical analysis. The centrifuge used for development of this method is small, lightweight, and portable for the field applications described in this protocol. Project scoping considerations, deployment of equipment and system layout options, and results from various field and laboratory quality control experiments are described. The testing confirmed the applicability of the protocol for the determination of many inorganic and organic chemicals sorbed on suspended sediment, including metals, pesticides, polycyclic aromatic hydrocarbons, and

  16. Quantifying Domestic Used Electronics Flows using a Combination of Material Flow Methodologies: A US Case Study.

    Miller, T Reed; Duan, Huabo; Gregory, Jeremy; Kahhat, Ramzy; Kirchain, Randolph

    2016-06-07

    This paper describes the scope, methods, data, and results of a comprehensive quantitative analysis of generation, stock, and collection of used computers and monitors in the United States , specifically desktops, laptops, CRT monitors, and flat panel monitors in the decade leading up to 2010. Generation refers to used electronics coming directly out of use or postuse storage destined for disposal or collection, which encompasses a variety of organizations gathering used electronics for recycling or reuse. Given the lack of actual statistics on flows of used electronics, two separate approaches, the sales obsolescence method (SOM) and the survey scale-up method (SSUM), were used in order to compare the results attained and provide a range for estimated quantities. This study intentionally sought to capture the uncertainty in the estimates. To do so, uncertainty in each data set was incorporated at each stage using Monte Carlo simulations for SOM and establishing scenarios for SSUM. Considering the average results across both methods, we estimate that in 2010 the U.S. generated 130-164 thousand metric tons of used computers and 128-153 thousand tons of used monitors, of which 110-116 thousand tons of used computers and 105-106 thousand tons of used monitors were collected for further reuse, recycling, or export. While each approach has its strengths and weaknesses, both the SOM and the SSUM appear to be capable of producing reasonable ranges of estimates for the generation and collection of used electronics.

  17. A study of grout flow pattern analysis

    Lee, S. Y.; Hyun, S.

    2013-01-01

    A new disposal unit, designated as Salt Disposal Unit no. 6 (SDU6), is being designed for support of site accelerated closure goals and salt nuclear waste projections identified in the new Liquid Waste System plan. The unit is cylindrical disposal vault of 380 ft diameter and 43 ft in height, and it has about 30 million gallons of capacity. Primary objective was to develop the computational model and to perform the evaluations for the flow patterns of grout material in SDU6 as function of elevation of grout discharge port, and slurry rheology. A Bingham plastic model was basically used to represent the grout flow behavior. A two-phase modeling approach was taken to achieve the objective. This approach assumes that the air-grout interface determines the shape of the accumulation mound. The results of this study were used to develop the design guidelines for the discharge ports of the Saltstone feed materials in the SDU6 facility. The focusing areas of the modeling study are to estimate the domain size of the grout materials radially spread on the facility floor under the baseline modeling conditions, to perform the sensitivity analysis with respect to the baseline design and operating conditions such as elevation of discharge port, discharge pipe diameter, and grout properties, and to determine the changes in grout density as it is related to grout drop height. An axi-symmetric two-phase modeling method was used for computational efficiency. Based on the nominal design and operating conditions, a transient computational approach was taken to compute flow fields mainly driven by pumping inertia and natural gravity. Detailed solution methodology and analysis results are discussed here

  18. Effects of luminal flow and nucleotides on [Ca(2+)](i) in rabbit cortical collecting duct.

    Woda, Craig B; Leite, Maurilo; Rohatgi, Rajeev; Satlin, Lisa M

    2002-09-01

    Nucleotide binding to purinergic P2 receptors contributes to the regulation of a variety of physiological functions in renal epithelial cells. Whereas P2 receptors have been functionally identified at the basolateral membrane of the cortical collecting duct (CCD), a final regulatory site of urinary Na(+), K(+), and acid-base excretion, controversy exists as to whether apical purinoceptors exist in this segment. Nor has the distribution of receptor subtypes present on the unique cell populations that constitute Ca(2+) the CCD been established. To examine this, we measured nucleotide-induced changes in intracellular Ca(2+) concentration ([Ca(2+)](i)) in fura 2-loaded rabbit CCDs microperfused in vitro. Resting [Ca(2+)](i) did not differ between principal and intercalated cells, averaging approximately 120 nM. An acute increase in tubular fluid flow rate, associated with a 20% increase in tubular diameter, led to increases in [Ca(2+)](i) in both cell types. Luminal perfusion of 100 microM UTP or ATP-gamma-S, in the absence of change in flow rate, caused a rapid and transient approximately fourfold increase in [Ca(2+)](i) in both cell types (P < 0.05). Luminal suramin, a nonspecific P2 receptor antagonist, blocked the nucleotide- but not flow-induced [Ca(2+)](i) transients. Luminal perfusion with a P2X (alpha,beta-methylene-ATP), P2X(7) (benzoyl-benzoyl-ATP), P2Y(1) (2-methylthio-ATP), or P2Y(4)/P2Y(6) (UDP) receptor agonist had no effect on [Ca(2+)](i). The nucleotide-induced [Ca(2+)](i) transients were inhibited by the inositol-1,4,5-triphosphate receptor blocker 2-aminoethoxydiphenyl borate, thapsigargin, which depletes internal Ca(2+) stores, luminal perfusion with a Ca(2+)-free perfusate, or the L-type Ca(2+) channel blocker nifedipine. These results suggest that luminal nucleotides activate apical P2Y(2) receptors in the CCD via pathways that require both internal Ca(2+) mobilization and extracellular Ca(2+) entry. The flow-induced rise in [Ca(2+)](i) is

  19. Performance evaluation of a flow-down collecting solar system; Ryuka shunetsushiki solar system no seino hyoka

    Kanayama, K; Li, X; Baba, H; Endo, N [Kitami Institute of Technology, (Japan)

    1997-11-25

    The paper evaluated performance of a flow-down collecting solar system. The solar heat pump PV system is composed of a solar system, heat pump and PV, of which the heat collecting portion is a water-use horizontal evacuated double glass tube solar collector. As a result of the performance measurement, the necessity of fundamental improvement arose. Under an idea of disproving common sense of the original forced circulation solar system, a system was designed in which heat is collected by making the heat media reversely circulate and flow down in accordance with gravity. When the flow rate was 2m{sup 3}/h, the collecting rate reached a maximum, approximately 54% (36.9% before improvement). When the flow rate was 1.3-1.5m{sup 3}/h, the system can realize the maximum merit, and the collecting efficiency became approximately 50%. Helped by reduction in consumed power, the average system performance coefficient reached more than 85% (28.9% before improvement). The obtainable energy rate rapidly increased to 2.9 times more than before improvement. Further, the consumed power of pump was decreased 65% from before improvement when the flow rate was 2.4m{sup 3}/h. 2 refs., 5 figs.

  20. Study of flow behavior in all-vanadium redox flow battery using spatially resolved voltage distribution

    Bhattarai, Arjun; Wai, Nyunt; Schweiss, Rüdiger; Whitehead, Adam; Scherer, Günther G.; Ghimire, Purna C.; Nguyen, Tam D.; Hng, Huey Hoon

    2017-08-01

    Uniform flow distribution through the porous electrodes in a flow battery cell is very important for reducing Ohmic and mass transport polarization. A segmented cell approach can be used to obtain in-situ information on flow behaviour, through the local voltage or current mapping. Lateral flow of current within the thick felts in the flow battery can hamper the interpretation of the data. In this study, a new method of segmenting a conventional flow cell is introduced, which for the first time, splits up both the porous felt as well as the current collector. This dual segmentation results in higher resolution and distinct separation of voltages between flow inlet to outlet. To study the flow behavior for an undivided felt, monitoring the OCV is found to be a reliable method, instead of voltage or current mapping during charging and discharging. Our approach to segmentation is simple and applicable to any size of the cell.

  1. Flow model study of 'Monju' reactor vessel

    Miyaguchi, Kimihide

    1980-01-01

    In the case of designing the structures in nuclear reactors, various problems to be considered regarding thermo-hydrodynamics exist, such as the distribution of flow quantity and the pressure loss in reactors and the thermal shock to inlet and outlet nozzles. In order to grasp the flow characteristics of coolant in reactors, the 1/2 scale model of the reactor structure of ''Monju'' was attached to the water flow testing facility in the Oarai Engineering Center, and the simulation experiment has been carried out. The flow characteristics in reactors clarified by experiment and analysis so far are the distribution of flow quantity between high and low pressure regions in reactors, the distribution of flow quantity among flow zones in respective regions of high and low pressure, the pressure loss in respective parts in reactors, the flow pattern and the mixing effect of coolant in upper and lower plenums, the effect of the twisting angle of inlet nozzles on the flow characteristics in lower plenums, the effect of internal cylinders on the flow characteristics in upper plenums and so on. On the basis of these test results, the improvement of the design of structures in reactors was made, and the confirmation test on the improved structures was carried out. The testing method, the calculation method, the test results and the reflection to the design of actual machines are described. (Kako, I.)

  2. The study on flow characteristics of butterfly valve using flow visualization

    Yang, S. M.; Hong, S. D.; Song, D. S.; Park, J. K.; Park, J. I.; Shin, S. K.; Kim, H. J.

    2005-01-01

    Flow visualization of butterfly valve is tested for four types(15 deg., 30 .deg., 45 .deg., and 90 .deg.) of valve opening angle. The inner flow characteristics of valve are studied. The flow variation was measured using a high speed camera which takes 500 frames per second with 1024 x 1024 pixels. These captured images were used for calculation to analyze two dimensional flow velocity of the valve. The smaller opening angle, the more increasing the differential pressure of a butterfly valve. Therefore, we know that the complex flow is occurred by increasing the differential pressure. And it is found that the flowing backward is more increased according to the increase of the opening angle of a butterfly valve. However, its flow pattern is similar to a simple pipe flow when the opening angle is 90 .deg.

  3. COMPARATIVE STUDY OF HONEY COLLECTED FROM ...

    lanez

    2014-06-30

    Jun 30, 2014 ... content, electrical conductivity, total dissolved solids, color intensity ... used in this study on the basis of date of harvest, geographical origin. ... The determination of physical and chemical parameters such as content of water, ...

  4. Case study on ground water flow (8)

    1999-02-01

    The report comprises research activities made in fiscal year 1997 under the contract of Japan Nuclear Fuel Cycle Development Center and the main items are: (1) Evaluation of water permeability through discontinuous hard bedrock in deep strata in relevant with underground disposal of radioactive wastes, (2) Three dimensional analysis of permeated water in bedrock, including flow analysis in T ono district using neuro-network and modification of Evaporation Logging System, (3) Development of hydraulic tests and necessary equipment applicable to measurements of complex dielectric constants of contaminated soils using FUDR-V method, this giving information on soil component materials, (4) Investigation methods and modeling of hydraulics in deep strata, (5) Geological study of ground water using environmental isotopes such as 14 C, 36 Cl and 4 He, particularly measurement of ages of ground water using an accelerator-mass spectrometer, and (6) Re-submerging phenomena affecting the long-term geological stability. (S. Ohno)

  5. Case study on ground water flow (8)

    NONE

    1999-02-01

    The report comprises research activities made in fiscal year 1997 under the contract of Japan Nuclear Fuel Cycle Development Center and the main items are: (1) Evaluation of water permeability through discontinuous hard bedrock in deep strata in relevant with underground disposal of radioactive wastes, (2) Three dimensional analysis of permeated water in bedrock, including flow analysis in T ono district using neuro-network and modification of Evaporation Logging System, (3) Development of hydraulic tests and necessary equipment applicable to measurements of complex dielectric constants of contaminated soils using FUDR-V method, this giving information on soil component materials, (4) Investigation methods and modeling of hydraulics in deep strata, (5) Geological study of ground water using environmental isotopes such as {sup 14}C, {sup 36}Cl and {sup 4}He, particularly measurement of ages of ground water using an accelerator-mass spectrometer, and (6) Re-submerging phenomena affecting the long-term geological stability. (S. Ohno)

  6. Man-made flows from a fish's perspective: autonomous classification of turbulent fishway flows with field data collected using an artificial lateral line.

    Tuhtan, Jeffrey A; Fuentes-Perez, Juan Francisco; Toming, Gert; Schneider, Matthias; Schwarzenberger, Richard; Schletterer, Martin; Kruusmaa, Maarja

    2018-05-25

    The lateral line system provides fish with advanced mechanoreception over a wide range of flow conditions. Inspired by the abilities of their biological counterparts, artificial lateral lines have been developed and tested exclusively under laboratory settings. Motivated by the lack of flow measurements taken in the field which consider fluid-body interactions, we built a fish-shaped lateral line probe. The device is outfitted with 11 high-speed (2.5 kHz) time-synchronized pressure transducers, and designed to capture and classify flows in fish passage structures. A total of 252 field measurements, each with a sample size of 132 000 discrete sensor readings were recorded in the slots and across the pools of vertical slot fishways. These data were used to estimate the time-averaged flow velocity (R 2   =  0.952), which represents the most common metric to assess fishway flows. The significant contribution of this work is the creation and application of hydrodynamic signatures generated by the spatial distribution of pressure fluctuations on the fish-shaped body. The signatures are based on the collection of the pressure fluctuations' probability distributions, and it is shown that they can be used to automatically classify distinct flow regions within the pools of three different vertical slot fishways. For the first time, field data from operational fishway measurements are sampled and classified using an artificial lateral line, providing a completely new source of bioinspired flow information.

  7. Analysis method of high-order collective-flow correlations based on the concept of correlative degree

    Zhang Weigang

    2000-01-01

    Based on the concept of correlative degree, a new method of high-order collective-flow measurement is constructed, with which azimuthal correlations, correlations of final state transverse momentum magnitude and transverse correlations can be inspected respectively. Using the new method the contributions of the azimuthal correlations of particles distribution and the correlations of transverse momentum magnitude of final state particles to high-order collective-flow correlations are analyzed respectively with 4π experimental events for 1.2 A GeV Ar + BaI 2 collisions at the Bevalac stream chamber. Comparing with the correlations of transverse momentum magnitude, the azimuthal correlations of final state particles distribution dominate high-order collective-flow correlations in experimental samples. The contributions of correlations of transverse momentum magnitude of final state particles not only enhance the strength of the high-order correlations of particle group, but also provide important information for the measurement of the collectivity of collective flow within the more constraint district

  8. Competition between Local Collisions and Collective Hydrodynamic Feedback Controls Traffic Flows in Microfluidic Networks

    Belloul, M.; Engl, W.; Colin, A.; Panizza, P.; Ajdari, A.

    2009-05-01

    By studying the repartition of monodisperse droplets at a simple T junction, we show that the traffic of discrete fluid systems in microfluidic networks results from two competing mechanisms, whose significance is driven by confinement. Traffic is dominated by collisions occurring at the junction for small droplets and by collective hydrodynamic feedback for large ones. For each mechanism, we present simple models in terms of the pertinent dimensionless parameters of the problem.

  9. A feasability study of color flow doppler vectorization for automated blood flow monitoring.

    Schorer, R; Badoual, A; Bastide, B; Vandebrouck, A; Licker, M; Sage, D

    2017-12-01

    An ongoing issue in vascular medicine is the measure of the blood flow. Catheterization remains the gold standard measurement method, although non-invasive techniques are an area of intense research. We hereby present a computational method for real-time measurement of the blood flow from color flow Doppler data, with a focus on simplicity and monitoring instead of diagnostics. We then analyze the performance of a proof-of-principle software implementation. We imagined a geometrical model geared towards blood flow computation from a color flow Doppler signal, and we developed a software implementation requiring only a standard diagnostic ultrasound device. Detection performance was evaluated by computing flow and its determinants (flow speed, vessel area, and ultrasound beam angle of incidence) on purposely designed synthetic and phantom-based arterial flow simulations. Flow was appropriately detected in all cases. Errors on synthetic images ranged from nonexistent to substantial depending on experimental conditions. Mean errors on measurements from our phantom flow simulation ranged from 1.2 to 40.2% for angle estimation, and from 3.2 to 25.3% for real-time flow estimation. This study is a proof of concept showing that accurate measurement can be done from automated color flow Doppler signal extraction, providing the industry the opportunity for further optimization using raw ultrasound data.

  10. A Study of Laminar Backward-Facing Step Flow

    Davidson, Lars; Nielsen, Peter V.

    The laminar flow for a backwards facing step is studied. This work was initially part of the work presented in. In that work low-Reynolds number effects was studied, and the plan was also to include laminar flow. However, it turned out that when the numerical predictions of the laminar flow (Re...

  11. Experimental studies of occupation times in turbulent flows

    Mann, J.; Ott, Søren; Pécseli, H.L.

    2003-01-01

    The motion of passively convected particles in turbulent flows is studied experimentally in approximately homogeneous and isotropic turbulent flows, generated in water by two moving grids. The simultaneous trajectories of many small passively convected, neutrally buoyant, polystyrene particles...

  12. Study of gas-water flow in horizontal rectangular channels

    Chinnov, E. A.; Ron'shin, F. V.; Kabov, O. A.

    2015-09-01

    The two-phase flow in the narrow short horizontal rectangular channels 1 millimeter in height was studied experimentally. The features of formation of the two-phase flow were studied in detail. It is shown that with an increase in the channel width, the region of the churn and bubble regimes increases, compressing the area of the jet flow. The areas of the annular and stratified flow patterns vary insignificantly.

  13. [Injuries in parasailing. A collective GOTS study].

    Krüger-Franke, M; Pförringer, W

    1991-03-01

    Regulations permitting the sport of paragliding were issued on April 15, 1987 by the Department of Transportation in Germany. With the rising number participants in this sport, the number of reported injuries has also been steadily increasing. The herein reported epidemiologic study presents the incidence, localization and degree of injuries associated with this sport documented in Germany, Austria and Switzerland. During the period from 1. 1. 1987 until 31. 12. 1989, 218 injuries associated with paragliding were reported in the above mentioned countries. 181 occurred during landing, 28 during start procedures and 9 during flight. The average age of the patients was 29.6 years. The analysis of the localization of the trauma related injury documented 33.9% spinal injuries, 13.8% injuries of the upper extremities and 41.3% of the lower extremities. Over half of these injuries were treated surgically and in 54 instances permanent disability remained. In the sport of paragliding the lower extremities are at greatest risk for injury during the landing phase. Proper equipment especially sturdy shoes, exact training in landing techniques and especially improved instruction in procedures during aborted or crash landings of the individual paraglider is required to reduce the frequency of these injuries.

  14. The spherical segmented Langmuir probe in a flowing thermal plasma: numerical model of the current collection

    E. Séran

    2005-07-01

    Full Text Available The segmented Langmuir probe (SLP has been recently proposed by one of the authors (Lebreton, 2002 as an instrument to derive the bulk velocity of terrestrial or planetary plasmas, in addition to the electron density and temperature that are routinely measured by Langmuir probes. It is part of the scientific payload on the DEMETER micro-satellite developed by CNES. The basic concept of this probe is to measure the current distribution over the surface using independent collectors under the form of small spherical caps and to use the angular anisotropy of these currents to obtain the plasma bulk velocity in the probe reference frame. In order to determine the SLP capabilities, we have developed a numerical PIC (Particles In Cell model which provides a tool to compute the distribution of the current collected by a spherical probe. Our model is based on the simultaneous determination of the charge densities in the probe sheath and on the probe surface, from which the potential distribution in the sheath region can be obtained. This method is well adapted to the SLP problem and has some advantages since it provides a natural control of the charge neutrality inside the simulation box, allows independent mesh sizes in the sheath and on the probe surface, and can be applied to complex surfaces. We present in this paper initial results obtained for plasma conditions corresponding to a Debye length equal to the probe radius. These plasma conditions are observed along the Demeter orbit. The model results are found to be in very good agreement with those published by Laframboise (1966 for a spherical probe in a thermal non-flowing plasma. This demonstrates the adequacy of the computation method and of the adjustable numerical parameters (size of the numerical box and mesh, time step, number of macro-particles, etc. for the considered plasma-probe configuration. We also present the results obtained in the case of plasma flowing with mesothermal conditions

  15. The spherical segmented Langmuir probe in a flowing thermal plasma: numerical model of the current collection

    E. Séran

    2005-07-01

    Full Text Available The segmented Langmuir probe (SLP has been recently proposed by one of the authors (Lebreton, 2002 as an instrument to derive the bulk velocity of terrestrial or planetary plasmas, in addition to the electron density and temperature that are routinely measured by Langmuir probes. It is part of the scientific payload on the DEMETER micro-satellite developed by CNES. The basic concept of this probe is to measure the current distribution over the surface using independent collectors under the form of small spherical caps and to use the angular anisotropy of these currents to obtain the plasma bulk velocity in the probe reference frame. In order to determine the SLP capabilities, we have developed a numerical PIC (Particles In Cell model which provides a tool to compute the distribution of the current collected by a spherical probe. Our model is based on the simultaneous determination of the charge densities in the probe sheath and on the probe surface, from which the potential distribution in the sheath region can be obtained. This method is well adapted to the SLP problem and has some advantages since it provides a natural control of the charge neutrality inside the simulation box, allows independent mesh sizes in the sheath and on the probe surface, and can be applied to complex surfaces. We present in this paper initial results obtained for plasma conditions corresponding to a Debye length equal to the probe radius. These plasma conditions are observed along the Demeter orbit. The model results are found to be in very good agreement with those published by Laframboise (1966 for a spherical probe in a thermal non-flowing plasma. This demonstrates the adequacy of the computation method and of the adjustable numerical parameters (size of the numerical box and mesh, time step, number of macro-particles, etc. for the considered plasma-probe configuration. We also present the results obtained in the case of plasma flowing with mesothermal conditions

  16. Comparative study of heat transfer and pressure drop during flow boiling and flow condensation in minichannels

    Mikielewicz Dariusz

    2014-09-01

    Full Text Available In the paper a method developed earlier by authors is applied to calculations of pressure drop and heat transfer coefficient for flow boiling and also flow condensation for some recent data collected from literature for such fluids as R404a, R600a, R290, R32,R134a, R1234yf and other. The modification of interface shear stresses between flow boiling and flow condensation in annular flow structure are considered through incorporation of the so called blowing parameter. The shear stress between vapor phase and liquid phase is generally a function of nonisothermal effects. The mechanism of modification of shear stresses at the vapor-liquid interface has been presented in detail. In case of annular flow it contributes to thickening and thinning of the liquid film, which corresponds to condensation and boiling respectively. There is also a different influence of heat flux on the modification of shear stress in the bubbly flow structure, where it affects bubble nucleation. In that case the effect of applied heat flux is considered. As a result a modified form of the two-phase flow multiplier is obtained, in which the nonadiabatic effect is clearly pronounced.

  17. 77 FR 44710 - Information Collection Activities (Depreciation Studies)

    2012-07-30

    ... (Depreciation Studies) ACTION: 60-day notice and request for comments. SUMMARY: As part of its continuing effort... Office of Management and Budget (OMB) the information collection--Rail Depreciation Studies--further... information collection: Title: Rail Depreciation Studies. OMB Control Number: 2140-XXXX. Form Number: None...

  18. Study on the flow reduction of forced flow superconducting magnet and its stable operation condition

    Sugimoto, Makoto [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    2001-03-01

    cryogenic pump and not obtain in the design phase. For the estimation in design phase, evaluation equations of the flow reduction based on the helium expansion model were developed. The flow reduction by AC losses is predictable by helium expansion model even in the design phase on which the conductor friction and pump performances are not obtained. The phenomenon of flow reduction of the forced flow coil has been applied for coil quench detection and has been developed by Japan Atomic Energy Research Institute (JAERI). It is named the 'fluid method' and essential technology for quench detection of large scale forced flow superconducting coil as fusion magnets and superconducting magnetic energy storage (SMES) coil. In the fluid method, the inlet flow reduction is caused by Joule heating on the normal zone of superconducting coil. The fluid method has no electric noise in its detection. This is an advantage for pulsed operation in comparison with other electrical quench detection systems. There are no quantitative considerations between the inlet flow reduction and Joule heating on the coil in previous studies. The flow reduction for the quench detection has been determined by the operation experience of forced flow superconducting coil. The evaluation method for the flow reduction for the quench detection was developed. The energy consumption in the coil by Joule heating was defined from the inlet flow reduction. It means the quench detection duration from the normal initiation is available. And it makes the protection of the superconducting coil more reliable. It is a new idea on the study of flow reduction and applicable not only fusion magnet but also all of forced flow superconducting coils like a SMES coil. (author)

  19. Studies of thermal-hydrodynamic flow instability, (3)

    Suzuoki, Akira

    1978-01-01

    In the flow system in which large density change occurs midway, sometimes steady flow cannot be maintained according to the conditions, and pulsating flow or the scamper of flow occurs. This phenomenon is called flow instability, and is noticed as one of the causes to obstruct the normal operation in boilers, BWRs and the steam generators for FBRs with parallel evaporating tube system. In the pulsating instability, there are density wave oscillation and pressure wave oscillation. The author has studied the density wave oscillation occurring in the steam generators for FBRs and in this paper, the role played by two-phase flow regarding the occurrence of flow instability, and the effect of the existence of interphase slip on the role played by two-phase flow are reported. The theoretical analysis and the results of the analysis taking a steam generator heated with sodium as the example are described. Regarding flow stability, two-phase flow part generates the variation of weight velocity with different phase in steam single phase part, accepting enthalpy variation in water single phase part. In this action, the effect of interphase slip was observed, and the variation of reverse phase is apt to occur in slip flow as compared with homogeneous flow. Accordingly, flow instability is apt to occur in slip flow. (Kako, I.)

  20. The art and science of flow control - case studies using flow visualization methods

    Alvi, F. S.; Cattafesta, L. N., III

    2010-04-01

    Active flow control (AFC) has been the focus of significant research in the last decade. This is mainly due to the potentially substantial benefits it affords. AFC applications range from the subsonic to the supersonic (and beyond) regime for both internal and external flows. These applications are wide and varied, such as controlling flow transition and separation over various external components of the aircraft to active management of separation and flow distortion in engine components and over turbine and compressor blades. High-speed AFC applications include control of flow oscillations in cavity flows, supersonic jet screech, impinging jets, and jet-noise control. In this paper we review some of our recent applications of AFC through a number of case studies that illustrate the typical benefits as well as limitations of present AFC methods. The case studies include subsonic and supersonic canonical flowfields such as separation control over airfoils, control of supersonic cavity flows and impinging jets. In addition, properties of zero-net mass-flux (ZNMF) actuators are also discussed as they represent one of the most widely studied actuators used for AFC. In keeping with the theme of this special issue, the flowfield properties and their response to actuation are examined through the use of various qualitative and quantitative flow visualization methods, such as smoke, shadowgraph, schlieren, planar-laser scattering, and Particle image velocimetry (PIV). The results presented here clearly illustrate the merits of using flow visualization to gain significant insight into the flow and its response to AFC.

  1. Numerical study on flow rate limitation of open capillary channel flow through a wedge

    Ting-Ting Zhang

    2016-04-01

    Full Text Available The flow characteristics of slender-column flow in wedge-shaped channel under microgravity condition are investigated in this work. The one-dimensional theoretical model is applied to predict the critical flow rate and surface contour of stable flow. However, the one-dimensional model overestimates the critical flow rate for not considering the extra pressure loss. Then, we develop a three-dimensional simulation method with OpenFOAM, a computational fluid dynamics tool, to simulate various phenomena in wedge channels with different lengths. The numerical results are verified with the capillary channel flow experimental data on the International Space Station. We find that the three-dimensional simulation perfectly predicts the critical flow rates and surface contours under various flow conditions. Meanwhile, the general behaviors in subcritical, critical, and supercritical flow are studied in three-dimensional simulation considering variations of flow rate and open channel length. The numerical techniques for three-dimensional simulation is validated for a wide range of configurations and is hopeful to provide valuable guidance for capillary channel flow experiment and efficient liquid management in space.

  2. Hadronic energy spectra from nuclear collisions: Effects from collective transverse flow and the phase transition to quark matter

    Heinz, U.

    1988-11-01

    I give an overview of the processes determining the shape of energy spectra of hadrons emitted in relativistic nuclear collisions, and discuss how one can extract from them information on the presence of collective transverse flow and on the transition to quark-gluon matter in such collisions. 6 refs., 3 figs

  3. Negative elliptic flow of J/{psi}'s: A qualitative signature for charm collectivity at RHIC

    Krieg, D.; Bleicher, M. [Johann Wolfgang Goethe-Universitaet, Institut fuer Theoretische Physik, Frankfurt am Main (Germany)

    2009-01-15

    We discuss one of the most prominent features of the very recent preliminary elliptic flow data of J/{psi}-mesons from the PHENIX Collaboration (PHENIX Collaboration (C. Silvestre), arXiv:0806.0475 [nucl-ex]). Even within the rather large error bars of the measured data a negative elliptic flow parameter (v{sub 2}) for J/{psi} in the range of p{sub T}=0.5-2.5 GeV/c is visible. We argue that this negative elliptic flow at intermediate p{sub T} is a clear and qualitative signature for the collectivity of charm quarks produced in nucleus-nucleus reactions at RHIC. Within a parton recombination approach we show that a negative elliptic flow puts a lower limit on the collective transverse velocity of heavy quarks. The numerical value of the transverse flow velocity {beta}{sub T} for charm quarks that is necessary to reproduce the data is {beta}{sub T} (charm) {proportional_to}0.55-0.6c and therefore compatible with the flow of light quarks. (orig.) 3.

  4. CASH FINANCIAL FLOWS PERFORMANCE ON THE OCCASION OF COLLECTING STATE TREASURY BUDGETARY CLAIMS

    RISTI LUCIA

    2015-07-01

    Full Text Available The present paper analyzes the financial flows caused by the collection of taxes and other budget payments from businesses or other legal entities and individuals who have accounts with commercial banks, fact which amends the volume and structure of the execution of public funds, on the whole of public Treasury. The current legislation in Romania establishes the obligation for operators and other taxpayers to pay on their own initiative the debts they have to the state1 , otherwise, Ministry of Finance bodies2 are entitled and even obliged to undertake forced pursuing these state budget rights applying forced tracking forms to concerned taxpayers which are provided by law. In this respect, based on the information provided by its own accounting or tax decisions passed by the tax bodies; taxpayers, individuals or legal entities, submit payment documents whether to commercial banks where they have opened accounts or to operational units of Treasuries, if they have open available accounts ere, payment documents for their debts to the state and, all those transactions are subject to this research. Along with the cash settlement, the settlement of cashless payments for operators and other taxpayers who have bank accounts with commercial banks in order to pay their debts to the state, these can be achieved in three ways: on their own initiative; on the basis of payment documents deposited with commercial banks where they have opened their accounts on their own initiative; at the customs facilities in the case of import operations regarding state budget obligations connected to the nature of customs duties, excise duties, value added tax and; thirdly, on the tax authorities or customs initiative by forced tracking on the available accounts or other property of the debtor taxpayers.

  5. Numerical study of MHD supersonic flow control

    Ryakhovskiy, A. I.; Schmidt, A. A.

    2017-11-01

    Supersonic MHD flow around a blunted body with a constant external magnetic field has been simulated for a number of geometries as well as a range of the flow parameters. Solvers based on Balbas-Tadmor MHD schemes and HLLC-Roe Godunov-type method have been developed within the OpenFOAM framework. The stability of the solution varies depending on the intensity of magnetic interaction The obtained solutions show the potential of MHD flow control and provide insights into for the development of the flow control system. The analysis of the results proves the applicability of numerical schemes, that are being used in the solvers. A number of ways to improve both the mathematical model of the process and the developed solvers are proposed.

  6. Base flow and exhaust plume interaction. Part 1 : Experimental study

    Schoones, M.M.J.; Bannink, W.J.

    1998-01-01

    An experimental study of the flow field along an axi-symmetric body with a single operating exhaust nozzle has been performed in the scope of an investigation on base flow-jet plume interactions. The structure of under-expanded jets in a co-flowing supersonic free stream was described using

  7. Study of nonequilibrium dispersed two phase flow

    Reyes, J.N. Jr.

    1986-01-01

    Understanding the behavior of liquid droplets in a superheated steam environment is essential to the accurate prediction of nuclear fuel rod surface temperatures during the blowdown and reflood phase of a loss-of-coolant-accident (LOCA). In response to this need, this treatise presents several original and significant contributions to the field of thermofluid physics. The research contained herein presents a statistical derivation of the two-phase mass, momentum, and energy-conservation equations using a droplet continuity equation analogous to that used in the Kinetic Theory of Gases. Unlike the Eulerian volume and time-averaged conservation equations generally used to describe dispersed two-phase flow behavior, this statistical averaging approach results in an additional mass momentum or energy term in each of the respective conservation equations. Further, this study demonstrates that current definitions of the volumetric vapor generation rate used in the mass conservation equation are inappropriate results under certain circumstances. The mass conservation equation derived herein is used to obtain a new definition for the volumetric vapor-generation rate. Last, a simple two phase phenomenological model, based on the statistically averaged conservation equations, is presented and solved analytically. It is shown that the actual quality and vapor temperature, under these circumstances, depend on a single dimensionless group

  8. Collective flows of protons and $\\pi^-$ mesons in $^{2}$H + C, Ta and He plus C, Ta collisions at 3.4 GeV/nucleon

    Chkhaidze, L; Djobava, T; Kladnitskaya, E; Kharkhelauri, L; Uzhinsky, V

    2011-01-01

    Collective flows of protons and negative pions have been studied in (2)H + C, Ta and He + C, Ta collisions at an energy of 3.4 GeV/nucleon. The data have been obtained by the 2-m Propane Bubble Chamber (PBC-500) at JINR. It is found that the directed flow of protons and pi(-) mesons characterized by d /d(y) increases with increase of the mass numbers of colliding nucleus pairs; the elliptic proton flow points out of the reaction plane and also strengthens as the system mass increases; the negative pion directed flow is in the same reaction plane as the proton flow for the lighter (2H + C, He + C) systems and in the opposite direction for the heavier ((2)H + Ta, He + Ta) systems. In (2)H + C, He + C, C + C, C + Ne, (2)H + Ta, He + Ta, C + Cu, and C + Ta collisions, the linear dependence of directed and elliptic flow parameters from mass numbers of projectile and target nuclei, (A(P).A(T))(1/2), is similar for protons while for pi(-) mesons the dependence of directed flow parameters is stronger. The ultrarelati...

  9. Experimental studies of renal blood flow by digitized functional angiography

    Buersch, J.H.; Ochs, C.; Hahne, H.J.; Heintzen, P.H.

    1985-01-01

    New techniques of digital image processing have been experimentally tested for the assessment of renal blood flow. The underlying principle in functional angiography is the extraction of flow parameters. Basically, density-time variations of the contrast medium are analayzed from to each picture element of a 256x256 matrix. The real-time acquisition rate of images was 25/sec. For the calculation of angiographic flow a PDP 11/40 computer was used to interactively perform a time dependent segmentation of the renal arteries and the aorta. Subsequently, volume flow was calculated in relative units for the specific vascular segments under study. 15 control angiograms were made in 5 animals with cardiac output ranging between 0.8 to 2.2l/min. Unilateral renal blood flow was calculated as 24+-3.4% of pre-renal aortic flow without systematic side differences. Reproducibility from repeated flow measurements showed an SD of +-1.8% of the individual pre-renal aortic flow. Renal flow was also measured in 3 animals with an experimentally created 50% flow reduction of the left kidney. Angiographic flow in the left renal artery dropped to 12+-2% of pre-renal flow. The present experimental data suggest that digital angiography has sufficient diagnostic capabilities for the detection of abnormal renal blood flow. The technique may serve as a useful diagnostic adjunct to conventional angiography and has the potential of assisting in the evaluation of renal vascular hypertension. (orig.) [de

  10. What is the relationship between free flow and pressure flow studies in women?

    Duckett, Jonathan; Cheema, Katherine; Patil, Avanti; Basu, Maya; Beale, Sian; Wise, Brian

    2013-03-01

    The relationship between free flow (FFS) and pressure flow (PFS) voiding studies remains uncertain and the effect of a urethral catheter on flow rates has not been determined. The relationship between residuals obtained at FF and PFS has yet to be established. This was a prospective cohort study based on 474 consecutive women undergoing cystometry using different sized urethral catheters at different centres. FFS and PFS data were compared for different conditions and the relationship of residuals analysed for FFS and PFS. The null hypothesis was that urethral catheters do not produce an alteration in maximum flow rates for PFS and FF studies. Urethral catheterisation results in lower flow rates (p flows are corrected for voided volume (p flow rates are lower in women with DO than USI (p flow rates and vice versa. There was no significant difference between the mean residuals of the two groups (FFS vs PFS-two-tailed t = 0.54, p = 0.59). Positive residuals in FFS showed a good association with positive residuals in the PFS (r = 0.53, p flow rates. The relationship can be compared mathematically. The null hypothesis can be rejected.

  11. Noninvasive measurement of cerebrospinal fluid flow using an ultrasonic transit time flow sensor: a preliminary study.

    Pennell, Thomas; Yi, Juneyoung L; Kaufman, Bruce A; Krishnamurthy, Satish

    2016-03-01

    OBJECT Mechanical failure-which is the primary cause of CSF shunt malfunction-is not readily diagnosed, and the specific reasons for mechanical failure are not easily discerned. Prior attempts to measure CSF flow noninvasively have lacked the ability to either quantitatively or qualitatively obtain data. To address these needs, this preliminary study evaluates an ultrasonic transit time flow sensor in pediatric and adult patients with external ventricular drains (EVDs). One goal was to confirm the stated accuracy of the sensor in a clinical setting. A second goal was to observe the sensor's capability to record real-time continuous CSF flow. The final goal was to observe recordings during instances of flow blockage or lack of flow in order to determine the sensor's ability to identify these changes. METHODS A total of 5 pediatric and 11 adult patients who had received EVDs for the treatment of hydrocephalus were studied in a hospital setting. The primary EVD was connected to a secondary study EVD that contained a fluid-filled pressure transducer and an in-line transit time flow sensor. Comparisons were made between the weight of the drainage bag and the flow measured via the sensor in order to confirm its accuracy. Data from the pressure transducer and the flow sensor were recorded continuously at 100 Hz for a period of 24 hours by a data acquisition system, while the hourly CSF flow into the drip chamber was recorded manually. Changes in the patient's neurological status and their time points were noted. RESULTS The flow sensor demonstrated a proven accuracy of ± 15% or ± 2 ml/hr. The flow sensor allowed real-time continuous flow waveform data recordings. Dynamic analysis of CSF flow waveforms allowed the calculation of the pressure-volume index. Lastly, the sensor was able to diagnose a blocked catheter and distinguish between the blockage and lack of flow. CONCLUSIONS The Transonic flow sensor accurately measures CSF output within ± 15% or ± 2 ml

  12. CFD Validation Studies for Hypersonic Flow Prediction

    Gnoffo, Peter A.

    2001-01-01

    A series of experiments to measure pressure and heating for code validation involving hypersonic, laminar, separated flows was conducted at the Calspan-University at Buffalo Research Center (CUBRC) in the Large Energy National Shock (LENS) tunnel. The experimental data serves as a focus for a code validation session but are not available to the authors until the conclusion of this session. The first set of experiments considered here involve Mach 9.5 and Mach 11.3 N2 flow over a hollow cylinder-flare with 30 degree flare angle at several Reynolds numbers sustaining laminar, separated flow. Truncated and extended flare configurations are considered. The second set of experiments, at similar conditions, involves flow over a sharp, double cone with fore-cone angle of 25 degrees and aft-cone angle of 55 degrees. Both sets of experiments involve 30 degree compressions. Location of the separation point in the numerical simulation is extremely sensitive to the level of grid refinement in the numerical predictions. The numerical simulations also show a significant influence of Reynolds number on extent of separation. Flow unsteadiness was easily introduced into the double cone simulations using aggressive relaxation parameters that normally promote convergence.

  13. Sources for comparative studies of placentation I. Embryological collections

    Carter, Anthony Michael

    2008-01-01

    A rich source of material for comparative studies of the placenta is the collections made by pioneers in the field such as H.W. Mossman, A.A.W. Hubrecht and J.P. Hill. This overview gives a brief description of collections known to be available and information on how each can be accessed. Include...... are some of the major series of human and animal embryos, such as the Boyd and Carnegie collections, as these also house placental material....

  14. Experimental study of flow through compressor Cascade

    Satyam Panchal

    2017-09-01

    Full Text Available The objective of this research work is to study the behaviour of flow at the inlet, within the blade passage and at the exit of a compressor cascade. For this purpose, a cascade with six numbers of aerofoil blades was designed and constructed. The cascade was fitted on the cascade test tunnel. Out of six blades two were instrumented for measuring the pressure distribution on the pressure and suction surface. The blades had a parabolic camber line, with a maximum camber position at 40% of the chord from the leading edge of the blade. The profile of the blade was C4, height of the blade was 160 mm, chord length was 80 mm, camber angle was 45° and stagger angle was 30°. Similarly, the length of the cascade was 300 mm, span was 160 mm, pitch was 60 mm, the actual chord of the cascade was 80 mm, the axial chord of the cascade was 70 mm, the stagger angle of the cascade was 30° and the pitch-chord ratio was 0.75. The data was taken and analyzed at −500% of the axial chord before the cascade, −25% of the axial chord before the leading edge, 25%, 50%, 75% and 150% of the axial chord from the leading edge of the blade. The readings were taken from the cascade wall to the mid span position along the pitch wise direction. The angle of incidence was also changed during the experiment and varied from i=−50°, −30°, −10° to 5°.

  15. Experimental Study of Cavitation in Laminar Flow

    Croci , Kilian; Ravelet , Florent; ROBINET , Jean-Christophe; Danlos , Amélie

    2017-01-01

    An experimental setup has been especially developed in order to observe cavitation in laminar flows. Experiments have been carried out with a silicon oil of viscosity υ = 100cSt passing through a Venturi-type geometry with 18°/8° convergent/divergent angles respectively. The range of Reynolds numbers at the inlet section is between 350 and 1000. Two dynamic regimes are identified. They are characterized by two critical Reynolds numbers, induced by major hydrodynamic changes in the flow, in ad...

  16. THE EFFECT OF THE REYNOLDS NUMBER OF AIR FLOW TO THE PARTICLE COLLECTION EFFICIENCY OF A FIBROUS FILTER MEDIUM WITH CYLINDRICAL SECTION

    George P. Kouropoulos

    2014-01-01

    Full Text Available At this study an attempt for the theoretical approach of the Re ynolds number effect of air flow to the particle collection efficiency of a fibrous fil ter with cylindrical section will be made. Initially, a report of the air filtration models to fibrous filter media will be presented along with an explanation of both the parameters and the physical quantities which govern the air filtration process. Furthermore, the resul ting equation from the mathematical model will be applied to a real filter medium and the characteristic curves of filter efficiency will be drawn. The change of a filter medi um efficiency with regard to the Reynolds number of air flow that passes through the filt er, derived from the curves, will be studied. The general conclusion that we have is that as the Reynolds number of filtered air increases, the collection efficiency of the filter decreases.

  17. Study of transient burnout under flow reduction condition

    Iwamura, Takamichi

    1986-09-01

    Transient burnout characteristics of a fuel rod under a rapid flow reduction condition of a light water reactor were experimentally and analytically studied. The test sections were uniformly heated vertical tube and annulus with the heated length of 800 mm. Test pressures ranged 0.5 ∼ 3.9 MPa, heat fluxes 2,160 ∼ 3,860 KW/m 2 , and flow reduction rates 0.44 ∼ 770 %/s. The local flow condition during flow reduction transients were calculated with a separate flow model. The two-fluid/three-field thermal-hydraulic code, COBRA/TRAC, was also used to investigate the liquid film behavior on the heated surface. The major results obtained in the present study are as follows: The onset of burnout under a rapid flow reduction condition was caused by a liquid film dryout on the heated surface. With increasing flow reduction rate beyond a threshold, the burnout mass velocity at the inlet became lower than the steady-state burnout mass velocity. This is explained by the fact that the vapor flow rate continues to increase due to the delay of boiling boundary movement and the resultant high vapor velocity sustains the liquid film flow after the inlet flow rate reaches the steady-state burnout flow rate. The ratio of inlet burnout mass velocities between flow reduction transient and steady-state became smaller with increasing system pressure because of the lower vapor velocity due to the lower vapor specific volume. Flow reduction burnout occurred when the outlet quality agreed with the steady-state burnout quality within 10 %, suggesting that the local condition burnout model can be used for flow reduction transients. Based on this model, a method to predict the time to burnout under a flow reduction condition in a uniformly heated tube was developed. The calculated times to burnout agreed well with some experimental results obtained by the Author, Cumo et al., and Moxon et al. (author)

  18. Area Studies and Special Collections: Shared Challenges, Shared Strength

    Carter, Lisa R.; Whittaker, Beth M.

    2015-01-01

    Special collections and area studies librarians face similar challenges in the changing academic library environment, including the need to articulate the value of these specialized collections and to mainstream processes and practices into larger discovery, teaching, learning, and research efforts. For some institutions, these similarities have…

  19. Online recognition of the multiphase flow regime and study of slug flow in pipeline

    Guo Liejin; Bai Bofeng; Zhao Liang; Wang Xin; Gu Hanyang

    2009-01-01

    sensor performance. Among various flow patterns of gas-liquid flow, slug flow occurs frequently in the petroleum, chemical, civil and nuclear industries. In the offshore oil and gas field, the maximum slug length and its statistical distribution are very important for the design of separator and downstream processing facility at steady state operations. However transient conditions may be encountered in the production, such as operational upsets, start-up, shut-down, pigging and blowdown, which are key operational and safety issues related to oil field development. So it is necessary to have an understanding the flow parameters under transient conditions. In this paper, the evolution of slug length along a horizontal pipe in gas-liquid flow is also studied in details and then an experimental study of flowrate transients in slug flow is provided. Also, the special gas-liquid flow phenomena easily encountered in the life span of offshore oil fields, called severe slugging, is studied experimentally and some results are presented.

  20. Miscellaneous flow discharge measurements collected downstream of Brandon Road Lock and Dam

    Department of the Interior — Flow discharges were measured in the Des Plaines River from approximately river mile 286 to river mile 284 on October 19–21, 2015 using Teledyne Rio Grande 1200 kHz...

  1. Numerical and Experimental Study of Pump Sump Flows

    Wei-Liang Chuang

    2014-01-01

    Full Text Available The present study analyzes pump sump flows with various discharges and gate submergence. Investigations using a three-dimensional large eddy simulation model and an acoustic Doppler velocimeter are performed. Flow patterns and velocity profiles in the approaching flow are shown to describe the flow features caused by various discharges and gate submergence. The variation of a large-scale spanwise vortex behind a sluice gate is examined and discussed. The suction effect on approaching flow near the pipe column is examined using numerical modeling. To gain more understanding of the vortices variation, a comparison between time-averaged and instantaneous flow patterns is numerically conducted. Additionally, swirl angle, a widely used index for evaluating pump efficiency, is experimentally and numerically examined under various flow conditions. The results indicate that the pump becomes less efficient with increasing discharge and gate submergence. The fluctuation of the free surface over the pump sump is also discussed.

  2. 77 FR 2567 - Proposed Collection of Information for the Job Corps Process Study; New Collection

    2012-01-18

    ...: Job Corps center management and staff; Job Corps students; Job Corps partner organizations' staff; and... Human Resources Managers 8 Academic Instruction Managers 24 Career Technical Training (CTT) Managers 24... the Job Corps Process Study; New Collection AGENCY: Employment and Training Administration (ETA...

  3. Regional blood flow studies with radioisotopes

    Holman, B.L.; McNiel, B.J.; Adelstein, S.J.

    1975-01-01

    The methodological approaches to blood flow analysis include (1) diffusible indicator methods, (2) clearance techniques and (3) nondiffusible indicator methods. In each case, accurate measurements of blood flow can be obtained by developing mathematical models which relate the time-dependent observation derived from following the fate of a radiotracer as a function of time to the physiological process itself. Application of these models to biological systems involves constraints and necessitates compromises which may affect the validity of the measurements. Nevertheless, when these techniques are carefully applied and adequately validated, they have provided critical physiological information about such organ systems as the brain and kidney and promise to provide diagnostic information in patients with suspected coronary and peripheral vascular disease

  4. Studying apoptotic cell death by flow cytometry

    Ormerod, Michael G.

    1998-01-01

    Full text: Programmed cell death (PCD) is of fundamental importance in the normal development of an animal and also in tumour biology and radiation biology. During PCD a sequence of changes occurs in cells giving rise to an apoptotic cascade of events. The main elements of this cascade are rapidly being elucidated. Flow cytometry has been used to follow many of these changes. It also has been used to quantify the number of apoptotic cells in a culture and, more recently, in clinical samples. In this review, the properties of apoptotic cells and the main feature of apoptotic cascade will be described. How flow cytometry can be used to follow changes during the apoptotic cascade will be discussed

  5. Flow Studies of Decelerators at Supersonic Speeds

    1959-01-01

    Wind tunnel tests recorded the effect of decelerators on flow at various supersonic speeds. Rigid parachute models were tested for the effects of porosity, shroud length, and number of shrouds. Flexible model parachutes were tested for effects of porosity and conical-shaped canopy. Ribbon dive brakes on a missile-shaped body were tested for effect of tension cable type and ribbon flare type. The final test involved a plastic sphere on riser lines.

  6. NMR studies of multiphase flows II

    Altobelli, S.A.; Caprihan, A.; Fukushima, E. [Lovelace Institutes, Albuquerque, NM (United States)] [and others

    1995-12-31

    NMR techniques for measurements of spatial distribution of material phase, velocity and velocity fluctuation are being developed and refined. Versions of these techniques which provide time average liquid fraction and fluid phase velocity have been applied to several concentrated suspension systems which will not be discussed extensively here. Technical developments required to further extend the use of NMR to the multi-phase flow arena and to provide measurements of previously unobtainable parameters are the focus of this report.

  7. Flow sorting in the study of teratocarcinoma cell differentiation

    G.H. Schaap (Gerard Hendrik)

    1984-01-01

    textabstractFlow cytometry is a technique by which particles (cells, subcellular fragments, bacteria) in aqueous suspension are passed one by one through a sensing region where optical (or electrical) signals are generated. These signals for each individual cell are collected and processed, and may

  8. Development and application of traffic flow information collecting and analysis system based on multi-type video

    Lu, Mujie; Shang, Wenjie; Ji, Xinkai; Hua, Mingzhuang; Cheng, Kuo

    2015-12-01

    Nowadays, intelligent transportation system (ITS) has already become the new direction of transportation development. Traffic data, as a fundamental part of intelligent transportation system, is having a more and more crucial status. In recent years, video observation technology has been widely used in the field of traffic information collecting. Traffic flow information contained in video data has many advantages which is comprehensive and can be stored for a long time, but there are still many problems, such as low precision and high cost in the process of collecting information. This paper aiming at these problems, proposes a kind of traffic target detection method with broad applicability. Based on three different ways of getting video data, such as aerial photography, fixed camera and handheld camera, we develop a kind of intelligent analysis software which can be used to extract the macroscopic, microscopic traffic flow information in the video, and the information can be used for traffic analysis and transportation planning. For road intersections, the system uses frame difference method to extract traffic information, for freeway sections, the system uses optical flow method to track the vehicles. The system was applied in Nanjing, Jiangsu province, and the application shows that the system for extracting different types of traffic flow information has a high accuracy, it can meet the needs of traffic engineering observations and has a good application prospect.

  9. Comparative study of incompressible and isothermal compressible flow solvers for cavitating flow dynamics

    Park, Sun Ho [Korea Maritime and Ocean University, Busan (Korea, Republic of); Rhee, Shin Hyung [Seoul National University, Seoul (Korea, Republic of)

    2015-08-15

    Incompressible flow solvers are generally used for numerical analysis of cavitating flows, but with limitations in handling compressibility effects on vapor phase. To study compressibility effects on vapor phase and cavity interface, pressure-based incompressible and isothermal compressible flow solvers based on a cell-centered finite volume method were developed using the OpenFOAM libraries. To validate the solvers, cavitating flow around a hemispherical head-form body was simulated and validated against the experimental data. The cavity shedding behavior, length of a re-entrant jet, drag history, and the Strouhal number were compared between the two solvers. The results confirmed that computations of the cavitating flow including compressibility effects improved the reproduction of cavitation dynamics.

  10. Experimental and spectroscopic study of flow actuation phenomena using DC discharge at a Mach 3 flow.

    Shin, J.; Narayanaswamy, V.; Raja, L.; Clemens, N.

    2006-10-01

    A study of flow actuation phenomena of DC discharge will be presented. An array of pin-like electrodes is flush mounted on a co-planar ceramic actuator that is inserted in the test section. The different discharge structures -- diffuse, constricted, and mixed mode -- are observed in the presence of a flow. A discernable actuation, as visualized by schlieren imaging, is achieved by diffuse discharge, whereas the constricted discharge does not show detectable flow perturbation at the same current. The flow actuation in the form of an induced oblique shock occurs within one frame of laser schlieren imaging at 4.5 kHz. Rotational (gas) and vibrational temperatures are measured by fitting spectra of N2 and N2+ bands near 365-395 nm. Electronic temperatures are measured using Boltzmann plot of Fe (I) lines. Gas temperatures of diffuse discharges drop from ˜1500 K to ˜500 K in the presence of a flow while vibrational and electronic temperatures remain almost the same at ˜3000 K and ˜1.25 eV, respectively. Gas temperatures of constricted discharge are found to be similar with diffuse discharge whereas only diffuse discharge shows an actuation. An examination of spatial extent of the plasma reveals that the diffuse discharge occupies a larger region of the flow than the constricted discharge. This indicates that the flow actuation is dependent on flow dilatation which is governed by temperature rise as well as the spatial extent over which the temperature rise is observed.

  11. Ion collection by a sphere in a flowing plasma: 2. non-zero Debye length

    Hutchinson, I H

    2003-01-01

    The spatial distribution of ion flux to a sphere in a flowing collisionless plasma is calculated using a particle-in-cell code SCEPTIC. The code is validated by comparing with prior stationary-plasma and approximate calculations. Comprehensive results are provided for ion temperatures 1 and 0.1 times the electron temperature, and for Debye length from 0.01 to 100 times the probe size. A remarkable qualitatively new result is obtained: over a range of Debye lengths from roughly 0.1 to 10 times the probe radius at T i = 0.1T e , the downstream side of the probe receives substantially higher flux density than the upstream side when the flow is subsonic. This unexpected reversal of the asymmetry reinforces the need for these fully self-consistent calculations, but renders the use of the flux ratio for Mach-probe purposes problematic, even for deriving the direction of the flow

  12. Asymmetric energy flow in liquid alkylbenzenes: A computational study

    Leitner, David M.; Pandey, Hari Datt

    2015-01-01

    Ultrafast IR-Raman experiments on substituted benzenes [B. C. Pein et al., J. Phys. Chem. B 117, 10898–10904 (2013)] reveal that energy can flow more efficiently in one direction along a molecule than in others. We carry out a computational study of energy flow in the three alkyl benzenes, toluene, isopropylbenzene, and t-butylbenzene, studied in these experiments, and find an asymmetry in the flow of vibrational energy between the two chemical groups of the molecule due to quantum mechanical vibrational relaxation bottlenecks, which give rise to a preferred direction of energy flow. We compare energy flow computed for all modes of the three alkylbenzenes over the relaxation time into the liquid with energy flow through the subset of modes monitored in the time-resolved Raman experiments and find qualitatively similar results when using the subset compared to all the modes

  13. Numerical study on flow and pollutant dispersion inside street canyons

    Yunkai, Yang

    2013-01-01

    This thesis analyzes the characteristics of flow pattern and vehicle-emitted pollutant dispersion in roughness surface layer. In an urban environment, wind flow and transported-pollutant source interfere strongly with buildings and other roughness elements on the surface ground, which results in complex characteristics of flow pattern and pollutant dispersion in 3D circumstances. The present study intends to simplify the research domain and investigate the fundamental modeling problems that e...

  14. Thermal freeze-out and longitudinally non-uniform collective expansion flow in relativistic heavy ion collisions

    Feng Sheng Qin; LianShouLiu

    2002-01-01

    The non-uniform longitudinal flow model (NUFM) proposed recently is extended to include also the transverse flow. The resulting longitudinally non-uniform collective expansion model (NUCEM) is applied to the calculation of rapidity distribution of kaons, lambdas and protons in relativistic heavy ion collisions at CERN-SPS energies. The model results are compared with the 200 A GeV/c S-S and 158 A GeV/c Pb-Pb collision data. The central dips observed in experiments are reproduced in a natural way. It is found that the depth of the central dip depends on the magnitude of the parameter e and the mass of produced particles, i.e. the non-uniformity of the longitudinal flow which is described by the parameter e determines the depth of the central dip for produced particles. Comparing with one-dimensional non-uniform longitudinal flow model, the rapidity distribution of lighter strange particle kaon also shows a dip due to the effect of transverse flow

  15. Optimizing traffic flow efficiency by controlling lane changes: collective, group and user optima

    Yao, S.; Knoop, V.L.; van Arem, B.

    2017-01-01

    Lane changes can lead to disturbances in traffic flow, whilst the uneven distribution of traffic over different lanes as a result of lane changes can also lead to instabilities and congestion on one specific lane. Therefore, giving advice on lane change can be beneficial for both individual drivers

  16. 76 FR 23539 - Proposed Information Collection; Comment Request; Commodity Flow Survey

    2011-04-27

    ... planning organizations, and the business community. The Commodity Flow Survey is co-sponsored by the Bureau of Transportation Statistics, Research and Innovative Technology Administration, Department of..., industry, and mode of transportation. The Census Bureau will publish these shipment characteristics for the...

  17. Collective Influence of Multiple Spreaders Evaluated by Tracing Real Information Flow in Large-Scale Social Networks.

    Teng, Xian; Pei, Sen; Morone, Flaviano; Makse, Hernán A

    2016-10-26

    Identifying the most influential spreaders that maximize information flow is a central question in network theory. Recently, a scalable method called "Collective Influence (CI)" has been put forward through collective influence maximization. In contrast to heuristic methods evaluating nodes' significance separately, CI method inspects the collective influence of multiple spreaders. Despite that CI applies to the influence maximization problem in percolation model, it is still important to examine its efficacy in realistic information spreading. Here, we examine real-world information flow in various social and scientific platforms including American Physical Society, Facebook, Twitter and LiveJournal. Since empirical data cannot be directly mapped to ideal multi-source spreading, we leverage the behavioral patterns of users extracted from data to construct "virtual" information spreading processes. Our results demonstrate that the set of spreaders selected by CI can induce larger scale of information propagation. Moreover, local measures as the number of connections or citations are not necessarily the deterministic factors of nodes' importance in realistic information spreading. This result has significance for rankings scientists in scientific networks like the APS, where the commonly used number of citations can be a poor indicator of the collective influence of authors in the community.

  18. Collective Influence of Multiple Spreaders Evaluated by Tracing Real Information Flow in Large-Scale Social Networks

    Teng, Xian; Pei, Sen; Morone, Flaviano; Makse, Hernán A.

    2016-01-01

    Identifying the most influential spreaders that maximize information flow is a central question in network theory. Recently, a scalable method called “Collective Influence (CI)” has been put forward through collective influence maximization. In contrast to heuristic methods evaluating nodes’ significance separately, CI method inspects the collective influence of multiple spreaders. Despite that CI applies to the influence maximization problem in percolation model, it is still important to examine its efficacy in realistic information spreading. Here, we examine real-world information flow in various social and scientific platforms including American Physical Society, Facebook, Twitter and LiveJournal. Since empirical data cannot be directly mapped to ideal multi-source spreading, we leverage the behavioral patterns of users extracted from data to construct “virtual” information spreading processes. Our results demonstrate that the set of spreaders selected by CI can induce larger scale of information propagation. Moreover, local measures as the number of connections or citations are not necessarily the deterministic factors of nodes’ importance in realistic information spreading. This result has significance for rankings scientists in scientific networks like the APS, where the commonly used number of citations can be a poor indicator of the collective influence of authors in the community. PMID:27782207

  19. Flow visualization studies of bodies with square cross sections

    Chapman, G. T.; Clarkson, M. H.

    1983-01-01

    A water-tunnel study was conducted of four bodies. A solution of sodium fluorescein coating the body provided visualization of vortices and feeding sheets and isolated dots of methyl blue dye provided visualization of stream lines. These data, along with published oil-flow photos, were analyzed to develop the topological representation of the flows in cross-flow planes. Presented are the development of the flow along the body at fixed angles of attack and at a fixed body station with changes in angle of attack. Effects of roll angle, body corner radius, and nose bluntness are illustrated.

  20. Study of magnetized accretion flow with cooling processes

    Kuldeep Singh

    2018-02-09

    Feb 9, 2018 ... 2University of Delhi, South Campus, Delhi 110 021, India. ∗ ... Abstract. We have studied shock in magnetized accretion flow/funnel flow in case of neutron star with .... where Ap is the area of cross-section of the flux tube.

  1. Contribution to the study of rotating disc induced MHD flows

    Herve, P.

    1983-01-01

    Influence of a magnetic field on electroconductor viscous fluid flow generated by disks in rotation is studied here. Flow in rectilinear conduct is first studied, together with velocity, force and current line repartition. Then a case more general is dealt with a toroidal conduct with disk drive. The influence of electric conductivity and of the thickness of the mobile disk are detailed. Couple study leads to think to a transmission by fluid variable by magnetic field variations. At last, a radial flow with a source in the middle of it is studied with a disk rotation. Analysis of velocity and pressure evolution shows a pump effect [fr

  2. Numerical study of the bubbly flow regime in micro-channel flow boiling

    Bhuvankar, Pramod; Dabiri, Sadegh

    2017-11-01

    Two-phase flow accompanied by boiling in micro-channel heat sinks is an effective means for heat removal from computer chips. We present a numerical study of flow boiling in micro-channels with conjugate heat transfer with a focus on the bubbly flow regime. The bubbles are assumed to nucleate at a pre-determined location and frequency. The Navier Stokes equations are solved using a single fluid formulation with the Front tracking method. Phase change is implemented using the deficit in heat flux across the bubble interface. The analytical solution for bubble growth in a superheated liquid is used as a benchmark to validate the mentioned numerical method. Water and FC-72 are studied as the operating fluids in a micro-channel made of Copper with a focus on hotspot mitigation. The micro-channel of cross-section 231 μm × 1000 μm , is used to study the effects of vertical up-flow, vertical down-flow and horizontal flow of the mentioned fluids on the heat transfer coefficients. A simple film model accounting for mass and energy conservation is applied wherever the bubble approaches closer than a cell width to the wall. The results of the simulation are compared with existing experimental data for bubble growth rates and heat transfer coefficients.

  3. Study of groundwater collection protocols on the IPEN/CNEN-SP campus

    Marques, Joyce R.; Villa, Sabrina M.; Monteiro, Lucilena R.; Cotrim, Marycel E.B.; Pires, Maria Aparecida F.

    2013-01-01

    As per Brazilian Health Ministry's evaluation, industry is the second activity that most contaminates the soil in Sao Paulo Metropolitan region. In order to assess this scenario and keep a continuous logging of IPEN's installations effect over chemical compounds levels, and to improve the installation radioactive logging, in the region under its campus influence, since 2006, IPEN performs the groundwater monitoring, in the region where it is located. Collections are performed bimonthly in seven monitoring wells, evaluating 17 parameters. These values are compared to the ones established by CONAMA 396/08 Resolution, which provides the groundwater classification and environmental guidelines to chemically stable compounds. So far IPEN keeps the wells in good conditions and performs sampling methods studies to adequate it to current legal standards. The groundwater collection method and the wells characterization, concerning the anionic species content (F - , Cl - , Br - , NO 2 - , NO 3 - , PO 4 -3 e SO 4 -2 ), are evaluated in the present study. The purge procedure requirement was also evaluated. The well purging is the procedure for withdrawing water from inside the well, so the collection is performed only after the water level restoration, thereby ensuring that the water collected represents the aquifer. The use of 'bailer', which requires purging, and a called 'low flow pump', which requires no purging for sample collection, was also evaluated. These methods were selected in this study because they are recommended by CETESB 6410/88, the local standard to groundwater sample collection. Thus some anions concentrations in groundwater sampled with different purging procedures and collection were compared. The concentration change in each well performed with the same collection procedure was compared with the other collection methods variation in order to evaluate if these are equivalents. From the results obtained in this comparative study was possible to optimize the

  4. An Experimental Study of Oil / Water Flow in Horizontal Pipes

    Elseth, Geir

    2001-07-01

    The purpose of this thesis is to study the behaviour of the simultaneous flow of oil and water in horizontal pipes. In this connection, two test facilities are used. Both facilities have horizontal test sections with inner pipe diameters equal to 2 inches. The largest facility, called the model oil facility, has reservoirs of 1 m{sub 3} of each medium enabling flow rates as high as 30 m{sub 3}/h, which corresponds to mixture velocities as high as 3.35 m/s. The flow rates of oil and water can be varied individually producing different flow patterns according to variations in mixture velocity and input water cut. Two main classes of flows are seen, stratified and dispersed. In this facility, the main focus has been on stratified flows. Pressure drops and local phase fractions are measured for a large number of flow conditions. Among the instruments used are differential pressure transmitters and a traversing gamma densitometer, respectively. The flow patterns that appear are classified in flow pattern maps as functions of either mixture velocity and water cut or superficial velocities. From these experiments a smaller number of stratified flows are selected for studies of velocity and turbulence. A laser Doppler anemometer (LDA) is applied for these measurements in a transparent part of the test section. To be able to produce accurate measurements a partial refractive index matching procedure is used. The other facility, called the matched refractive index facility, has a 0.2 m{sub 3} reservoir enabling mainly dispersed flows. Mixture velocities range from 0.75 m/s to 3 m/s. The fluids in this facility are carefully selected to match the refractive index of the transparent part of the test section. A full refractive index matching procedure is carried out producing excellent optical conditions for velocity and turbulence studies by LDA. In addition, pressure drops and local phase fractions are measured. (author)

  5. Journaling and Self-Study in an International Research Collective

    Makaiau, Amber Strong; Leng, Lu; Fukui, Suguru

    2015-01-01

    Drawing from the theoretical foundations of reflective teaching, culturally responsive education, social constructivism, and self-study, this collaborative self-study investigates the role of an interactive online journal in an international research collective. Each from a different country, the authors came together through a common interest in…

  6. Experimental study for flow regime of downward air-water two-phase flow in a vertical narrow rectangular channel

    Kim, T. H.; Yun, B. J.; Jeong, J. H. [Pusan National University, Geunjeong-gu, Busan (Korea, Republic of)

    2015-05-15

    Studies were mostly about flow in upward flow in medium size circular tube. Although there are great differences between upward and downward flow, studies on vertical upward flow are much more active than those on vertical downward flow in a channel. In addition, due to the increase of surface forces and friction pressure drop, the pattern of gas-liquid two-phase flow bounded to the gap of inside the rectangular channel is different from that in a tube. The downward flow in a rectangular channel is universally applicable to cool the plate type nuclear fuel in research reactor. The sub-channel of the plate type nuclear fuel is designed with a few millimeters. Downward air-water two-phase flow in vertical rectangular channel was experimentally observed. The depth, width, and length of the rectangular channel is 2.35 mm, 66.7 mm, and 780 mm, respectively. The test section consists of transparent acrylic plates confined within a stainless steel frame. The flow patterns of the downward flow in high liquid velocity appeared to be similar to those observed in previous studies with upward flow. In downward flow, the transition lines for bubbly-slug and slug-churn flow shift to left in the flow regime map constructed with abscissa of the superficial gas velocity and ordinate of the superficial liquid velocity. The flow patterns observed with downward flow at low liquid velocity are different from those with upward flow.

  7. Experimental study of slab solar collection on the hydronic system of road

    Gao, Qing; Huang, Yong; Li, Ming; Liu, Yan [Jilin University, Changchun (China); Yan, Y.Y. [University of Nottingham (United Kingdom)

    2010-12-15

    This paper studied the slab solar collection (SSC) process, which is one of the essential compositions of road hydronic ice-snow melting (HISM) system that stores solar energy in summer to melt ice and snow on the road in winter. Its aim is to find out the heat transfer characteristic of the SSC and heat collecting efficiency and the influence of pipe spacing and flow rate by experiment. As shown in experimental results, the average heat collecting capacity is about 150-250 W/m{sup 2} in natural summer condition, while the solar radiation intensity is about 300-1000 W/m{sup 2}. It is shown that the increment of fluid flow results in the increment of heat collection efficiency, while the increment of pipe spacing results in the decrement of the efficiency in experiment modes. The results show that the road slab can obtain about 30% solar heat in summertime, and the solar collection can lower the pavement temperature and reduce the insolation weathering. (author)

  8. Study of turbulent natural-circulation flow and low-Prandtl-number forced-convection flow

    Chung, K.S.; Thompson, D.H.

    1980-01-01

    Calculational methods and results are discussed for the coupled energy and momentum equations of turbulent natural circulation flow and low Prandtl number forced convection flow. The objective of this paper is to develop a calculational method for the study of the thermal-hydraulic behavior of coolant flowing in a liquid metal fast breeder reactor channel under natural circulation conditions. The two-equation turbulence model is used to evaluate the turbulent momentum transport property. Because the analogy between momentum transfer and heat transfer does not generally hold for low Prandtl number fluid and natural circulation flow conditions, the turbulent thermal conductivity is calculated independently using equations similar to the two-equation turbulence model. The numerical technique used in the calculation is the finite element method

  9. Burnout in subcooled flow boiling of water. A visual experimental study

    Celata, G.P.; Mariani, A.; Zummo, G. [ENEA, Engineering Div., National Institute of Thermal Fluid-Dynamics, Rome (Italy); Cumo, M. [University of Rome la Sapienza, Rome (Italy)

    2000-12-01

    The objective of the present work is to perform a photographic study of the burnout in highly subcooled flow boiling, in order to provide a qualitative description of the flow pattern under different conditions of boiling regime: ONB (onset of nucleate boiling), subcooled flow boiling and thermal crisis. In particular, the flow visualisation is focused on the phenomena occurring on the heated wall during the thermal crisis up to the physical burnout of the heater. Vapour bubble parameters are measured from flow images recorded, while the wall temperature is measured with an indirect method, by recording the heater elongation during all flow regimes studied. The combination of bubble parameters and wall temperature measurements as well as direct observations of the flow pattern, for all flow regimes, are collected in graphs which provide a useful global point of view of boiling phenomena, especially during boiling crisis. Under these conditions, a detailed analysis of the mechanisms leading to the critical heat flux is reported, and the so called events sequence, from thermal crisis occurrence up to heater burnout, is illustrated. (authors)

  10. Burnout in subcooled flow boiling of water. A visual experimental study

    Celata, G.P.; Mariani, A.; Zummo, G.; Cumo, M.

    2000-01-01

    The objective of the present work is to perform a photographic study of the burnout in highly subcooled flow boiling, in order to provide a qualitative description of the flow pattern under different conditions of boiling regime: ONB (onset of nucleate boiling), subcooled flow boiling and thermal crisis. In particular, the flow visualisation is focused on the phenomena occurring on the heated wall during the thermal crisis up to the physical burnout of the heater. Vapour bubble parameters are measured from flow images recorded, while the wall temperature is measured with an indirect method, by recording the heater elongation during all flow regimes studied. The combination of bubble parameters and wall temperature measurements as well as direct observations of the flow pattern, for all flow regimes, are collected in graphs which provide a useful global point of view of boiling phenomena, especially during boiling crisis. Under these conditions, a detailed analysis of the mechanisms leading to the critical heat flux is reported, and the so called events sequence, from thermal crisis occurrence up to heater burnout, is illustrated. (authors)

  11. Experimental Setup For Study of Drop Deformation In Air Flow

    Basalaev Sergey

    2017-01-01

    Full Text Available Experimental study for study of deformation of drops in air flow is considered. Experimental setup includes a module for obtaining the drops, an air flow system and measuring system. Module for formation of drops is in the form of vertically arranged dropper with capillary with the possibility of formation of fixed drops. Air flow supply system comprises an air pump coupled conduit through a regulating valve with a cylindrical pipe, installed coaxially with dropper. The measuring system includes the video camera located with possibility of visualization of drop and the Pitot gage for measurement of flow rate of air located in the output section of branch pipe. This experimental setup allows to provide reliable and informative results of the investigation of deformation of drops in the air flow.

  12. Flow visualization study of post-critical heat flux in inverted flow

    Babelli, I.; Revankar, S.T.; Ishii, M.

    1994-01-01

    A visual study of film boiling was carried out to determine the flow regime transition in the post-CHF region for a transient bottom reflooding of a hot transparent test section. The effect of test liquid subcooling and inlet velocity on flow transition as well as on the quench front propagation was investigated. The respective ranges for liquid velocity and subcooling were 1.8-26.8 cm/s, and 20-45 C, respectively. The test liquid was Freon 113 which was introduced into the bottom of the quartz test section whose walls were maintained well above the film boiling temperature of the test liquid, via a transparent heat transfer fluid. The flow regimes observed down stream of the upward moving quench front were the rough wavy, the agitated, and the dispersed droplet/ligaments in agreement with a steady state, two-phase core injection study carried on recently by one of the authors. A correlation for the flow regime transition between the inverted annular and the dispersed droplet/ligament flow patterns was developed. The correlation showed a marked dependence on the void fraction at the CHF location and hence on the flow regime encountered in the pre-CHF region. (orig.)

  13. Power flow studies of magnetically insulated lines

    McDaniel, D.H.; Poukey, J.W.; Bergeron, K.D.; VanDevender, J.P.; Johnson, D.L.

    1977-01-01

    The designs for relativistic electron beam accelerators with power levels of 20 to 100 TW are greatly restricted by the inductance of a single diode of reasonable size. This fact leads to modular designs of very large accelerators. One concept uses several small insulators at a large radius arranged around the accelerator center. The total effective inductance is then low, but the energy must then be transported by self-magnetic insulated vacuum lines to the target volume. A triplate vacuum line configuration eases many mechanical support problems and allows more A-K gaps or feeds to be packaged around a given radius. This type of vacuum transmission line was chosen for initial experiments at Sandia. The experiments were conducted on the MITE (Magnetically Insulated Transmission Experiment) accelerator. The water pulse forming lines are connected to a vacuum triplate line through a conventional stacked insulator. Diagnostics on the experiment consisted of: (1) input V; (2) input I; (3) I monitors at the input, middle, and output of both the center conductor and ground plane of the transmission line; (4) magnetic energy analyzer to view peak electron energy in the A-K gap; (5) calorimetry; and (6) Faraday cups to look at electron current flowing across the transmission line. The main goal of the experiment is to obtain input impedance of the transmission line as a function of voltage and to measure electron loss currents. These measurements are compared to theoretical models for the input impedance and energy losses

  14. School Collective Efficacy and Bullying Behaviour: A Multilevel Study

    Olsson, Gabriella; Låftman, Sara Brolin; Modin, Bitte

    2017-01-01

    As with other forms of violent behaviour, bullying is the result of multiple influences acting on different societal levels. Yet the majority of studies on bullying focus primarily on the characteristics of individual bullies and bullied. Fewer studies have explored how the characteristics of central contexts in young people’s lives are related to bullying behaviour over and above the influence of individual-level characteristics. This study explores how teacher-rated school collective efficacy is related to student-reported bullying behaviour (traditional and cyberbullying victimization and perpetration). A central focus is to explore if school collective efficacy is related similarly to both traditional bullying and cyberbullying. Analyses are based on combined information from two independent data collections conducted in 2016 among 11th grade students (n = 6067) and teachers (n = 1251) in 58 upper secondary schools in Stockholm. The statistical method used is multilevel modelling, estimating two-level binary logistic regression models. The results demonstrate statistically significant between-school differences in all outcomes, except traditional bullying perpetration. Strong school collective efficacy is related to less traditional bullying perpetration and less cyberbullying victimization and perpetration, indicating that collective norm regulation and school social cohesion may contribute to reducing the occurrence of bullying. PMID:29261114

  15. School Collective Efficacy and Bullying Behaviour: A Multilevel Study

    Gabriella Olsson

    2017-12-01

    Full Text Available As with other forms of violent behaviour, bullying is the result of multiple influences acting on different societal levels. Yet the majority of studies on bullying focus primarily on the characteristics of individual bullies and bullied. Fewer studies have explored how the characteristics of central contexts in young people’s lives are related to bullying behaviour over and above the influence of individual-level characteristics. This study explores how teacher-rated school collective efficacy is related to student-reported bullying behaviour (traditional and cyberbullying victimization and perpetration. A central focus is to explore if school collective efficacy is related similarly to both traditional bullying and cyberbullying. Analyses are based on combined information from two independent data collections conducted in 2016 among 11th grade students (n = 6067 and teachers (n = 1251 in 58 upper secondary schools in Stockholm. The statistical method used is multilevel modelling, estimating two-level binary logistic regression models. The results demonstrate statistically significant between-school differences in all outcomes, except traditional bullying perpetration. Strong school collective efficacy is related to less traditional bullying perpetration and less cyberbullying victimization and perpetration, indicating that collective norm regulation and school social cohesion may contribute to reducing the occurrence of bullying.

  16. School Collective Efficacy and Bullying Behaviour: A Multilevel Study.

    Olsson, Gabriella; Låftman, Sara Brolin; Modin, Bitte

    2017-12-20

    As with other forms of violent behaviour, bullying is the result of multiple influences acting on different societal levels. Yet the majority of studies on bullying focus primarily on the characteristics of individual bullies and bullied. Fewer studies have explored how the characteristics of central contexts in young people's lives are related to bullying behaviour over and above the influence of individual-level characteristics. This study explores how teacher-rated school collective efficacy is related to student-reported bullying behaviour (traditional and cyberbullying victimization and perpetration). A central focus is to explore if school collective efficacy is related similarly to both traditional bullying and cyberbullying. Analyses are based on combined information from two independent data collections conducted in 2016 among 11th grade students ( n = 6067) and teachers ( n = 1251) in 58 upper secondary schools in Stockholm. The statistical method used is multilevel modelling, estimating two-level binary logistic regression models. The results demonstrate statistically significant between-school differences in all outcomes, except traditional bullying perpetration. Strong school collective efficacy is related to less traditional bullying perpetration and less cyberbullying victimization and perpetration, indicating that collective norm regulation and school social cohesion may contribute to reducing the occurrence of bullying.

  17. Study on hydrodynamic crisis of two-phase flow

    Nigmatulin, B.I.; Ivandaev, A.I.

    1977-01-01

    The phenomenon of hydrodynamic crisis (locking) of a two-phase flow is investigated. A model of a disperseannular flow with an effective monodisperse nucleus is used for describing the motion of a mixture under near-critical conditions. Main differential equations of a flow in a channel are given; in particular, the differential laws of variation of the effective diameters of drops in the nucleus as a result of mass exchange between the mixture components are singled out. Questions of concretization of the model are discussed. The conditions for the attainment of the maximum rate of flow of the gas through the channel are studied, as well as the effect of the flow prehistory on the formation of critical conditions in the outlet cross-section

  18. Study on hydrodynamic crisis of two-phase flow

    Nigmatulin, B I; Ivandaev, A I [Moskovskij Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Mekhaniki

    1977-01-01

    The phenomenon of hydrodynamic crisis (locking) of a two-phase flow is investigated. A model of a disperse annular flow with an effective monodisperse nucleus is used for describing the motion of a mixture under near-critical conditions. Main differential equations of a flow in a channel are given; in particular, the differential laws of variation of the effective diameters of drops in the nucleus as a result of mass exchange between the mixture components are singled out. Questions of concretization of the model are discussed. The conditions for the attainment of the maximum rate of flow of the gas through the channel are studied, as well as the effect of the flow prehistory on the formation of critical conditions in the outlet cross-section.

  19. Numerical studies of transverse curvature effects on transonic flow stability

    Macaraeg, M. G.; Daudpota, Q. I.

    1992-01-01

    A numerical study of transverse curvature effects on compressible flow temporal stability for transonic to low supersonic Mach numbers is presented for axisymmetric modes. The mean flows studied include a similar boundary-layer profile and a nonsimilar axisymmetric boundary-layer solution. The effect of neglecting curvature in the mean flow produces only small quantitative changes in the disturbance growth rate. For transonic Mach numbers (1-1.4) and aerodynamically relevant Reynolds numbers (5000-10,000 based on displacement thickness), the maximum growth rate is found to increase with curvature - the maximum occurring at a nondimensional radius (based on displacement thickness) between 30 and 100.

  20. Theoretical and numerical study of highly anisotropic turbulent flows

    Biferale, L.; Daumont, I.; Lanotte, A.; Toschi, F.

    2004-01-01

    We present a detailed numerical study of anisotropic statistical fluctuations in stationary, homogeneous turbulent flows. We address both problems of intermittency in anisotropic sectors, and the relative importance of isotropic and anisotropic fluctuations at different scales on a direct numerical

  1. Flow cytometry approach for studying the interaction between ...

    Flow cytometry approach for studying the interaction between Bacillus mojavensis and Alternaria alternata. Asma Milet, Noreddine Kacem Chaouche, Laid Dehimat, Asma Ait Kaki, Mounira Kara Ali, Philippe Thonart ...

  2. Flow of nucleons and fragments in 40Ar+27Al collisions studied with antisymmetrized molecular dynamics

    Ono, A.; Horiuchi, H.

    1995-01-01

    Collective transverse momentum flow of nucleons and fragments in intermediate energy 40 Ar+ 27 Al collisions is calculated with the antisymmetrized molecular dynamics (AMD). The observed flow and its balance energy are reproduced well by calculation with the Gogny force which corresponds to the soft equation of state (EOS) of nuclear matter. The calculated absolute value of the fragment flow is larger than that of the nucleon flow in the negative flow region, which can be explained by the existence of two components of flow. In addition to many similarities, the difference in the deuteron flow is found between 12 C+ 12 C and 40 Ar+ 27 Al collisions, and its origin is investigated by studying the production mechanism of light fragments. We also investigate the dependence of the flow of nucleons and fragments on the stochastic collision cross section and the effective interaction, and conclude that the stiff EOS without momentum dependence of the mean field is not consistent with the experimental data

  3. Blood flow velocity in migraine attacks - a transcranial Doppler study

    Zwetsloot, C.P.; Caekebeke, J.F.V.; Jansen, J.C.; Odink, J.; Ferrari, M.D.

    1991-01-01

    A pulsed Doppler device was used to measure blood flow velocities in the common carotid artery, the extracranial part of the internal carotid artery, the external carotid artery, the middle cerebral artery, and the anterior cerebral artery in 31 migraneurs without aura (n=27) and with aura (n=4), both during and ouside an attack. The aims were to compare blood flow velocity during and between migraine attacks and to study asymmetries of the blood flow velocity. Compared with blood flow velocity values obtained in the attack-free interval, blood flow velocity was lower during attacks without aura in both common carotid arteries, but not in the other extra- and intracranial vessels which were examined. However, during attacks of migraine with aura, blood flow velocity tended to be lower in all examined vessels. There were no asymmetries of the blood flow velocity. It is suggested that during migraine attacks without aura there is a dissociation in blood flow regulation in the common carotid and middle cerebral arteries. 20 refs., 2 tabs

  4. Blood flow velocity in migraine attacks - a transcranial Doppler study

    Zwetsloot, C.P.; Caekebeke, J.F.V.; Jansen, J.C.; Odink, J.; Ferrari, M.D. (Rijksuniversiteit Leiden (Netherlands))

    1991-05-01

    A pulsed Doppler device was used to measure blood flow velocities in the common carotid artery, the extracranial part of the internal carotid artery, the external carotid artery, the middle cerebral artery, and the anterior cerebral artery in 31 migraneurs without aura (n=27) and with aura (n=4), both during and ouside an attack. The aims were to compare blood flow velocity during and between migraine attacks and to study asymmetries of the blood flow velocity. Compared with blood flow velocity values obtained in the attack-free interval, blood flow velocity was lower during attacks without aura in both common carotid arteries, but not in the other extra- and intracranial vessels which were examined. However, during attacks of migraine with aura, blood flow velocity tended to be lower in all examined vessels. There were no asymmetries of the blood flow velocity. It is suggested that during migraine attacks without aura there is a dissociation in blood flow regulation in the common carotid and middle cerebral arteries. 20 refs., 2 tabs.

  5. Dense Descriptors for Optical Flow Estimation: A Comparative Study

    Ahmadreza Baghaie

    2017-02-01

    Full Text Available Estimating the displacements of intensity patterns between sequential frames is a very well-studied problem, which is usually referred to as optical flow estimation. The first assumption among many of the methods in the field is the brightness constancy during movements of pixels between frames. This assumption is proven to be not true in general, and therefore, the use of photometric invariant constraints has been studied in the past. One other solution can be sought by use of structural descriptors rather than pixels for estimating the optical flow. Unlike sparse feature detection/description techniques and since the problem of optical flow estimation tries to find a dense flow field, a dense structural representation of individual pixels and their neighbors is computed and then used for matching and optical flow estimation. Here, a comparative study is carried out by extending the framework of SIFT-flow to include more dense descriptors, and comprehensive comparisons are given. Overall, the work can be considered as a baseline for stimulating more interest in the use of dense descriptors for optical flow estimation.

  6. Collective Study On Security Threats In VOIP Networks

    Muhammad Zulkifl Hasan

    2017-01-01

    Full Text Available The Collective study will critically evaluate the voice over internet protocol VOIP Security threats issues amp challenges in the communication over the network the solution provided by different vendors. Authors will be discussing all security issues different protocols but main focus will be on SIP protocol its implementation and vendors VOIP security system.

  7. TDA's validity to study 18O collectivity in terms of collective pair model

    Gao Yuanyi; Vitturi, A.; Catara, F.; Sambataro, M.

    1991-01-01

    Conclusion proved that if the authors calculate 18 O collective spectra in terms of the Collective Pair Model, the authors can get the positive low laying levels of 18 O which are of the particle particle pair, independent on the excitation of hole within closed shell. 1 - low laying levels are of non-collective 3 particle 1 hole states. 1 - fourth level is of collective 3 particle 1 hole states. 3 - low laying levels are of collective 3 particle 1 hole states. 1 - , 3 - low laying levels agree very well with the experiment data. Hence the TDA is sufficient for the calculations of 1 - ,3 - collective low levels of 18 O

  8. Study of the influence of diffusion on the flow velocity, for binary mixtures in Poiseuille and Couette flows

    Caetano Filho, E.

    1981-05-01

    The influence of diffusion on the flow of binary mixtures of incompressible fluids in POISEUILLE and COUETTE flows, is studied. The constitutive equations sugested by SAMPAIO and WILLIAMS and by STRUMINSKII for the constituent stress tensor and for the diffusive force are used. Results show that diffusion does not influence the flow in the case of planar and circular COUETTE flows. On the other hand, diffusion does play an important part in planar and circular POISEUILLE flows. (Author) [pt

  9. In vitro and in vivo studies of pulmonary artery flow

    Sahn, D.J.; Yoganathan, A.P.

    1986-01-01

    A variety of interesting intracardiac flow patterns have been recorded by pulsed and continuous wave Doppler technologies in humans with heart disease. Some of these patterns have, in fact, been difficult to explain and are now more easily understood using color Doppler flow mapping systems which show the spatial location of flow. The authors performed a number of studies in patients, as well as studies in in vitro systems to model some of the phenomenon that the authors observed in the pulmonary artery. Their studies with Doppler flow mapping in the clinical situation, in the in vitro model, and in the animal models of congenital heart disorders lend insights into the complex hydrodynamics present in the pulmonary artery

  10. COLLECTIVE LEADERSHIP: A Case Study of the All Blacks

    Thomas Johnson; Andrew J Martin; Farah R Palmer; Geoffrey Watson; Phil Ramsey

    2012-01-01

    This case study evaluates the development of a formal collective leadership approach by the All Blacks (New Zealand’s national men’s rugby team) management. The All Blacks have an astonishing 75% winning record in test matches over a hundred year period. This winning ethos is part of their organizational culture, which has been developed, nurtured and sustained since the inception of the first national team in 1903 (Palenski, 2003; Tobin, 2005). In this qualitative research study, primary ...

  11. Studies of heat transport to forced-flow He II

    Dresner, L.; Kashani, A.; Van Sciver, S.W.

    1985-01-01

    Analytical and experimental studies of heat transport to forced-flow He II are reported. The work is pertinent to the transfer of He II in space. An analytical model has been developed that establishes a condition for two-phase flow to occur in the transfer line. This condition sets an allowable limit to the heat leak into the transfer line. Experimental measurements of pressure drop and flow meter performances indicate that turbulent He II can be analyzed in terms of classical pressure drop correlations

  12. A continuous flow from sample collection to data acceptability determination using an automated system

    Fisk, J.F.; Leasure, C.; Sauter, A.D.

    1993-01-01

    In its role as regulator, EPA is the recipient of enormous reams of analytical data, especially within the Superfund Program. In order to better manage the volume of paper that comes in daily, Superfund has required its laboratories to provide data that is contained on reporting forms to be delivered also on a diskette for uploading into data bases for various purposes, such as checking for contractual compliance, tracking quality assurance parameters, and, ultimately, for reviewing the data by computer. This last area, automated review of the data, has generated programs that are not necessarily appropriate for use by clients other than Superfund. Such is the case with Los Alamos National Laboratory's Environmental Chemistry Group and its emerging subcontractor community, designed to meet the needs of the remedial action program at LANL. LANL is in the process of implementing an automated system that will be used from the planning stage of sample collection to the production of a project-specific report on analytical data quality. Included are electronic scheduling and tracking of samples, data entry, checking and transmission, data assessment and qualification for use, and report generation that will tie the analytical data quality back to the performance criteria defined prior to sample collection. Industry standard products will be used (e.g., ORACLE, Microsoft Excel) to ensure support for users, prevent dependence on proprietary software, and to protect LANL's investment for the future

  13. Gasoline on hands: preliminary study on collection and persistence.

    Darrer, Melinda; Jacquemet-Papilloud, Joëlle; Delémont, Olivier

    2008-03-05

    The identification of an arsonist remains one of the most difficult challenges a fire investigation has to face. Seeking and detection of traces of gasoline could provide a valuable information to link a suspect with an arson scene where gasoline was used to set-up the fire. In this perspective, a first study was undertaken to evaluate a simple, fast and efficient method for collecting gasoline from hands, and to assess its persistence over time. Four collection means were tested: PVC, PE and Latex gloves, as well as humidified filter paper. A statistical assessment of the results indicates that Latex and PVC gloves worn for about 20 min, as well as paper filter rubbed on hands, allow an efficient collection of gasoline applied to hands. Due to ease of manipulation and to a reduced amount of volatile compounds detected from the matrix, PVC gloves were selected for the second set of experiments. The evaluation of the persistence of gasoline on hands was then carried out using two initial quantities (500 and 1000 microl). Collection was made with PVC gloves after 0, 30 min, 1, 2 and 4h, on different volunteers. The results show a common tendency of massive evaporation of gasoline during the first 30 min: a continued but non-linear decrease was observed along different time intervals. The results of this preliminary study are in agreement with other previous researches conducted on the detection of flammable liquid residues on clothes, shoes and skin.

  14. 76 FR 40379 - New Proposed Collection; Comment Request; Study Logistic Formative Research Methodology Studies...

    2011-07-08

    ...; Comment Request; Study Logistic Formative Research Methodology Studies for the National Children's Study... Collection Title: Study Logistics Formative Research Methodology Studies for the National Children's Study... national longitudinal study of environmental influences (including physical, chemical, biological, and...

  15. Experimental study on downward two-phase flow in narrow rectangular channel

    Kim, T.H.; Jeong, J.H. [Pusan National Univ., Busan (Korea, Republic of)

    2014-07-01

    Adiabatic vertical two-phase flow of air and water through narrow rectangular channels was investigated. This study involved the observation of flow using a high speed camera and flow regimes were determined by image processing program using a MATLAB. The flows regimes in channel with downward flow are similar to those found by previous studies with upward flow. The flow regimes in downward flow at low liquid velocity are different from the previous studies in upward flow. The flow regimes can be classified into bubbly, cap-bubbly, slug and churn flow. (author)

  16. Numerical studies of rock-gas flow in Yucca Mountain

    Ross, B.; Amter, S.; Lu, Ning

    1992-02-01

    A computer model (TGIF -- Thermal Gradient Induced Flow) of two-dimensional, steady-state rock-gas flow driven by temperature and humidity differences is described. The model solves for the ''fresh-water head,'' a concept that has been used in models of variable-density water flow but has not previously been applied to gas flow. With this approach, the model can accurately simulate the flows driven by small differences in temperature. The unsaturated tuffs of Yucca Mountain, Nevada, are being studied as a potential site for a repository for high-level nuclear waste. Using the TGIF model, preliminary calculations of rock-gas flow in Yucca Mountain are made for four east-west cross-sections through the mountain. Calculations are made for three repository temperatures and for several assumptions about a possible semi-confining layer above the repository. The gas-flow simulations are then used to calculate travel-time distributions for air and for radioactive carbon-14 dioxide from the repository to the ground surface

  17. Study of the Transition Flow Regime using Monte Carlo Methods

    Hassan, H. A.

    1999-01-01

    This NASA Cooperative Agreement presents a study of the Transition Flow Regime Using Monte Carlo Methods. The topics included in this final report are: 1) New Direct Simulation Monte Carlo (DSMC) procedures; 2) The DS3W and DS2A Programs; 3) Papers presented; 4) Miscellaneous Applications and Program Modifications; 5) Solution of Transitional Wake Flows at Mach 10; and 6) Turbulence Modeling of Shock-Dominated Fows with a k-Enstrophy Formulation.

  18. A COMPREHENSIVE STUDY OF HOURLY AND DAILY SEWAGE FLOW RATES IN FLORIDA PUBLIC SCHOOLS.

    FOGARTY, WILLIAM J.; REEDER, MILTON E.

    A DETERMINATION OF THE HOURLY AND DAILY SEWAGE FLOW RATES IN FLORIDA PUBLIC SCHOOLS WAS MADE TO IDENTIFY THE FLOW CHARACTERISTICS AND TO PROVIDE A MORE PRECISE BASIS FOR THE ESTABLISHMENT OF DESIGN CRITERIA FOR SEWAGE DISPOSAL FACILITIES IN SCHOOLS. WATER FLOW DATA WAS COLLECTED FOR 158 SCHOOLS AND SEWAGE FLOW DATA FROM 42 SCHOOLS. THE FINDINGS…

  19. Whole study of nuclear matter collective motion in central collisions of heavy ions of the FOPI detector

    Bendarag, A.

    1999-01-01

    In this work we study the collective phenomena in the central collisions of heavy ions for the Au + Au, Xe + CsI and Ni + Ni systems at incident energies from 150 to 400 MeV/nucleon with the data of the FOPI detector. In order to describe completely the flow of the nuclear matter, we fit the double differential momentum distributions with two-dimensional Gaussian. We study the characteristic parameters of the collective flow (flow range, aspect ratios, flow parameter) versus the charge and the mass of the fragments as well as the incident energy and the centrality of the collisions. The transverse energy is used for selecting the central collisions. The method of the Gaussian fits requires also to reconstruct the reaction plane of the event. Then we correct the parameters for the finite number of particles effects and account for the influence of the acceptance of the detector. We confirm the importance of the thermal motion for the light charge or mass fragments and, conversely, the predominance of the collective motion for the heavy fragments. A common flow angle for all the types of particles is highlighted for the first time, demonstrating the power of the method of the Gaussian fits; The evolution of the other parameters confirms the observations done with other methods of flow analysis. These results should contribute to put constraints on the collision models and to enlarge our knowledge of the properties of the nuclear matter. (author)

  20. Flow visualization study of inverted annular flow of post dryout heat transfer region

    Ishii, M.; De Jarlais, G.

    1985-01-01

    The inverted annular flow is important in the area of LWR accident analysis in terms of the maximum cladding temperature and effectiveness of the emergency core cooling. However, the inverted annular flow thermal-hydraulics is not well understood due to its special heat transfer condition of film boiling. In view of this, the inverted flow is studied in detail experimentally. A new experimental apparatus has been constructed in which film boiling heat transfer can be established in a transparent test section. Data on liquid core stability, core break-up mechanism, and dispersed-core liquid slug and droplet sizes are obtained using F 113 as a test fluid. Both high speed movies and flash photographs are used

  1. Pan-Canadian assessment of pandemic immunization data collection: study methodology

    Sikora Christopher A

    2010-06-01

    Full Text Available Abstract Background The collection of individual-level pandemic (H1N1 2009 influenza immunization data was considered important to facilitate optimal vaccine delivery and accurate assessment of vaccine coverage. These data are also critical for research aimed at evaluating the new vaccine's safety and effectiveness. Systems used to collect immunization data include manual approaches in which data are collected and retained on paper, electronic systems in which data are captured on computer at the point of vaccination and hybrid systems which are comprised of both computerized and manual data collection components. This study's objective was to compare the efficiencies and perceptions of data collection methods employed during Canada's pandemic (H1N1 2009 influenza vaccination campaign. Methods/Design A pan-Canadian observational study was conducted in a convenience sample of public health clinics and healthcare institutions during the H1N1 vaccination campaign in the fall of 2009. The study design consisted of three stages: Stage 1 involved passive observation of the site's layout, processes and client flow; Stage 2 entailed timing site staff on 20 clients through five core immunization tasks: i client registration, ii medical history collection, iii medical history review, iv vaccine administration record keeping and v preparation of proof of vaccine administration for the client; in Stage 3, site staff completed a questionnaire regarding perceived usability of the site's data collection approach. Before the national study began, a pilot study was conducted in three seasonal influenza vaccination sites in Ontario, to both test that the proposed methodology was logistically feasible and to determine inter-rater reliability in the measurements of the research staff. Comparative analyses will be conducted across the range of data collection methods with respect to time required to collect immunization data, number and type of individual-level data

  2. Flow regulation in coronary vascular tree: a model study.

    Xinzhou Xie

    Full Text Available Coronary blood flow can always be matched to the metabolic demand of the myocardium due to the regulation of vasoactive segments. Myocardial compressive forces play an important role in determining coronary blood flow but its impact on flow regulation is still unknown. The purpose of this study was to develop a coronary specified flow regulation model, which can integrate myocardial compressive forces and other identified regulation factors, to further investigate the coronary blood flow regulation behavior.A theoretical coronary flow regulation model including the myogenic, shear-dependent and metabolic responses was developed. Myocardial compressive forces were included in the modified wall tension model. Shear-dependent response was estimated by using the experimental data from coronary circulation. Capillary density and basal oxygen consumption were specified to corresponding to those in coronary circulation. Zero flow pressure was also modeled by using a simplified capillary model.Pressure-flow relations predicted by the proposed model are consistent with previous experimental data. The predicted diameter changes in small arteries are in good agreement with experiment observations in adenosine infusion and inhibition of NO synthesis conditions. Results demonstrate that the myocardial compressive forces acting on the vessel wall would extend the auto-regulatory range by decreasing the myogenic tone at the given perfusion pressure.Myocardial compressive forces had great impact on coronary auto-regulation effect. The proposed model was proved to be consistent with experiment observations and can be employed to investigate the coronary blood flow regulation effect in physiological and pathophysiological conditions.

  3. A study of light collection efficiency in scintillation detectors

    Xiaoguang, Y.

    1984-01-01

    A group of computer programs was set up to study the light collection efficiency in scintillation detectors with rectangular cross sections. The input conditions can be chosen arbitrarily, including: the size, light attenuation length and refraction index of the scintillator and light guide, the refraction index of the coupling medium, the reflection characteristics of the walls, and the position of light sources. A few examples are discussed in this article. (orig.)

  4. Systematic study of source mask optimization and verification flows

    Ben, Yu; Latypov, Azat; Chua, Gek Soon; Zou, Yi

    2012-06-01

    Source mask optimization (SMO) emerged as powerful resolution enhancement technique (RET) for advanced technology nodes. However, there is a plethora of flow and verification metrics in the field, confounding the end user of the technique. Systemic study of different flows and the possible unification thereof is missing. This contribution is intended to reveal the pros and cons of different SMO approaches and verification metrics, understand the commonality and difference, and provide a generic guideline for RET selection via SMO. The paper discusses 3 different type of variations commonly arise in SMO, namely pattern preparation & selection, availability of relevant OPC recipe for freeform source and finally the metrics used in source verification. Several pattern selection algorithms are compared and advantages of systematic pattern selection algorithms are discussed. In the absence of a full resist model for SMO, alternative SMO flow without full resist model is reviewed. Preferred verification flow with quality metrics of DOF and MEEF is examined.

  5. NATO Advanced Study Institute on Molecular Physics and Hypersonic Flows

    1996-01-01

    Molecular Physics and Hypersonic Flows bridges the gap between the fluid dynamics and molecular physics communities, emphasizing the role played by elementary processes in hypersonic flows. In particular, the work is primarily dedicated to filling the gap between microscopic and macroscopic treatments of the source terms to be inserted in the fluid dynamics codes. The first part of the book describes the molecular dynamics of elementary processes both in the gas phase and in the interaction with surfaces by using quantum mechanical and phenomenological approaches. A second group of contributions describes thermodynamics and transport properties of air components, with special attention to the transport of internal energy. A series of papers is devoted to the experimental and theoretical study of the flow of partially ionized gases. Subsequent contributions treat modern computational techniques for 3-D hypersonic flow. Non-equilibrium vibrational kinetics are then described, together with the coupling of vibra...

  6. Overview of edge turbulence and zonal flow studies on TEXTOR

    Xu, Y.; Kraemer-Flecken, A.; Reiser, D.

    2008-01-01

    In the TEXTOR tokamak, the edge turbulence properties and turbulence-associated zonal flows have been systematically investigated both experimentally and theoretically. The experimental results include the investigation of self-organized criticality (SOC) behavior, the intermittent blob transport and the geodesic acoustic mode (GAM) zonal flows. During the Dynamic Ergodic Divertor (DED) operation in TEXTOR, the impact of an ergodized plasma boundary on edge turbulence, turbulent transport and the fluctuation propagation has also been studied in detail. The results show substantial influence by the DED on edge turbulence. The theoretical simulations for TEXTOR parameters show characteristic features of the GAM flows and strong reduction of the blob transport by the DED at the plasma periphery. Moreover, the modelling reveals the importance of the Reynolds stress in driving mean (or zonal) flows at the plasma edge in the ohmic discharge phase in TEXTOR. (author)

  7. An Experimental and numerical Study for squeezing flow

    Nathan, Rungun; Lang, Ji; Wu, Qianhong; Vucbmss Team

    2017-11-01

    We report an experimental and numerical study to examine the transient squeezing flow driven by sudden external impacts. The phenomenon is widely observed in industrial applications, e.g. squeeze dampers, or in biological systems, i.e. joints lubrication. However, there is a lack of investigation that captures the transient flow feature during the process. An experimental setup was developed that contains a piston instrumented with a laser displacement sensor and a pressure transducer. The heavy piston was released from rest, creating a fast compaction on the thin fluid gap underneath. The motion of the piston and the fluid pressure build-up was recorded. For this dynamic process, a CFD simulation was performed which shows excellent agreement with the experimental data. Both the numerical and experimental results show that, the squeezing flow starts with the inviscid limit when the viscous fluid effect has no time to appear, and thereafter becomes a developing flow, in which the inviscid core flow region decreases and the viscous wall region increases until the entire fluid gap is filled with viscous fluid flow. The study presented herein, filling the gap in the literature, will have broad impacts in industrial and biomedical applications. This research was supported by the National Science Foundation under Award 1511096, and supported by the Seed Grant from The Villanova Center for the Advancement of Sustainability in Engineering (VCASE).

  8. Study of transient burnout characteristics under flow reduction condition

    Iwamura, Takamichi; Kuroyanagi, Toshiyuki

    1984-03-01

    As part of a study of the thermal behavior of fuel rods during Power-Cooling-Mismatch (PCM) accidents in light water reactors, burnout characteristics in a uniformly heated, vertically oriented tube or annulus, under flow reduction condition, were experimentally studied. Test pressures ranged 0.1--3.9 MPa and flow reduction rates 0.44--1100%/s. An analytical method is developed to obtain the local mass velocity during a transient condition. The major results are as follows: With increasing flow reduction rate beyond a threshold, transient burnout mass velocity at the inlet was lower than that in steady state tests under the experimental pressures. The higher system pressure resulted in the less transient effects. At pressures higher than 2.0 MPa and flow reduction rates lower than 20%/s, the local burnout mass velocity agreed with the steady state burnout mass velocity, whereas the local burnout mass velocity became higher than the steady state burnout mass velocity at flow reduction rates higher than 20%/s. At pressures lower than 1 MPa, with increasing flow reduction rate beyond the threshold value of 2%/s, the local burnout mass velocity was lower than the steady state burnout mass velocity. An empirical correlation is presented to give the ratio of the transient to the steady state burnout mass velocities at the burnout location as a function of the steam-water density ratio and the flow reduction rate. The experimental results by Cumo et al. agree with the correlation. The correlation, however, cannot predict the experimental results at higher flow reduction rates beyond 40%/s. (author)

  9. Collective flow in 2.76 and 5.02 A TeV Pb + Pb collisions

    Zhao, Wenbin; Xu, Hao-jie [Peking University, Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Beijing (China); Song, Huichao [Peking University, Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Peking University, Center for High Energy Physics, Beijing (China)

    2017-09-15

    In this paper, we study and predict flow observables in 2.76 and 5.02 A TeV Pb + Pb collisions, using the iEBE-VISHNU hybrid model with TRENTo and AMPT initial conditions and with different forms of the QGP transport coefficients. With properly chosen and tuned parameter sets, our model calculations can nicely describe various flow observables in 2.76 A TeV Pb + Pb collisions, as well as the measured flow harmonics of all charged hadrons in 5.02 A TeV Pb + Pb collisions. We also predict other flow observables, including v{sub n}(p{sub T}) of identified particles, event-by-event v{sub n} distributions, event-plane correlations, (normalized) symmetric cumulants, non-linear response coefficients and p{sub T}-dependent factorization ratios, in 5.02 A TeV Pb + Pb collisions. We find many of these observables to remain approximately the same values as the ones in 2.76 A TeV Pb + Pb collisions. Our theoretical studies and predictions could shed light to the experimental investigations in the near future. (orig.)

  10. Effects of swirl in turbulent pipe flows : computational studies

    Nygaard, Frode

    2011-07-01

    The primary objective of this doctoral thesis was to investigate the effect of swirl in steady turbulent pipe flows. The work has been carried out by a numerical approach, with direct numerical simulations as the method of choice. A key target to pursue was the effects of the swirl on the wall friction in turbulent pipe flows. The motivation came from studies of rotating pipe flows in which drag reduction was achieved. Drag reduction was reported to be due to the swirl favourably influencing the coherent turbulent structures in the near-wall region. Based on this, it was decided to investigate if similar behaviour could be obtained by inducing a swirl in a pipe with a stationary wall. To do a thorough investigation of the general three-dimensional swirl flow and particularly of the swirl effects; chosen variations of mean and turbulent flow parameters were explored together with complementary flow visualizations. Two different approaches in order to induce the swirl in the turbulent pipe flow, have been carried out. However, the present thesis might be regarded to be comprised of three parts. The first part consists of the first approach to induce the swirl. Here a prescribed circumferential force was implemented in a serial open source Navier-Stokes solver. In the second approach, the swirl was intended induced by implementing structures at the wall. Simulations of flows through a pipe with one or more helical fin(s) at the pipe wall was decided to be performed. In order to pursue this approach, it was found necessary to do a parallelization of the existing serial numerical code. The key element of this parallelization has been included as a part of the present work. Additionally, the helical fin(s) were implemented into the code by use of an immersed boundary method. A validation of this work is also documented in the thesis. The work done by parallelizing the code and implementing an immersed boundary method constitutes the second part of the present thesis. The

  11. Study of two-phase critical flows through small breaches

    Chalant, Jean Marc; Willocx, Marc

    1981-06-01

    The first part of this academic document reports experimental works performed for the design and realisation of an installation (DALIDA) aimed at the study of critical flow rates through a hole. As this experimental study had to be given up for practical reasons, the authors focused on the theoretical study of this phenomenon. Based on a model proposed by Lackme for critical flows in long tubes, the authors developed a model which could be applied to the case of a tube ended by a hole. Numerical results have been obtained which are still to be experimentally confirmed [fr

  12. Contribution to the study of unsteady condensation in transonic flow

    Collignan, B.; Laali, A.R.

    1993-12-01

    The aim of this thesis is the study of transonic steam flows with condensation, especially at high pressure. This study includes a numerical part an experimental one. The modelling has consisted of introducing a spontaneous condensation model in a one-dimensional Euler code using steam-water thermodynamic tables. Calculations, performed with this code, are in good agreement with experimental results at low pressure. The experimental study has been undertaken on a high pressure experimental loop installed at the Bugey nuclear power plant. We have studied steam flows in nozzles. The results obtained show that a partial heterogeneous condensation occurs in these flows. This proportion is stronger if the expansion rate of the flow is low and if the inlet pressure is high. However, a correction factor is obtained for high pressure nucleation rate model from experimental results. No unsteady condensation has been observed for flows between 15 bars and 50 bars with the steam available at Bugey power plant. (authors). figs., 71 refs., 6 annexes

  13. Experimental studies of the laser-controlled collective ion accelerator

    Destler, W.W.; Rodgers, J.; Segalov, Z.

    1989-01-01

    Detailed experimental studies of a collective acceleration experiment in which a time-sequenced laser-generated ionization channel is used to control the propagation of an intense relativistic electron beamfront are presented. Ions trapped in the potential well at the beamfront are accelerated as the velocity of the beamfront is increased in a manner controlled by the time-dependent axial extent of the ionization channel. Beamfront propagation data for two different accelerating gradients are presented, together with results of ion acceleration studies for both gradients

  14. Analysis of cash flow ratios: A study on CMC

    Somnath Das

    2018-01-01

    Full Text Available Cash flow ratios help financial users get relevant information about financial resources for a given time. Cash flow ratios are now used more than the traditional ones because it is more effective and justified. Cash flow based ratios are especially surprising because they do not only play a significant role in the credit rating of evaluation, but also forecast the failure of a corporation. In this study, we perform an empirical investigation on a company named CMC. From the study, it is clear that the liquidity and solvency positions of the company were moderate whereas the company maintained low profitability. On the other hand, the efficiency and sufficiency ratios of the study give us a new look on financial judgement.

  15. Studying the collision energy dependence of elliptic and triangular flow with a hybrid model

    Auvinen, Jussi [Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany); Petersen, Hannah [Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany); Institut fuer Theoretische Physik, Goethe Universitaet, Frankfurt am Main (Germany)

    2014-07-01

    Elliptic flow has been one of the key observables for establishing the finding of the quark-gluon plasma (QGP) at the highest energies of Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). As a sign of collectively behaving matter, the elliptic flow is expected to decrease at lower beam energies, where the QGP is not produced. However, in the recent RHIC beam energy scan, it has been found that the inclusive charged hadron elliptic flow changes relatively little in magnitude within the energy range 7.7-39 GeV per nucleon-nucleon collision. We study the collision energy dependence of the elliptic and triangular flow utilizing a Boltzmann+hydrodynamics hybrid model. Such a hybrid model provides a natural framework for the transition from high collision energies, where the hydrodynamical description is essential, to smaller energies, where the hadron transport dominates. This approach is thus suitable for investigating the relative importance of these two mechanisms for the production of the collective flow at different beam energies.

  16. Flow visualization study of inverted annular flow of post dryout heat transfer region

    Ishii, M.; De Jarlais, G.

    1987-01-01

    The inverted annular flow is important in the area of LWR accident analysis in terms of the maximum cladding temperature and effectiveness of the emergency core cooling. However, the inverted annular flow thermal-hydraulics is not well understood due to its special heat transfer condition of film boiling. In view of this, the inverted flow is studied in detail experimentally. A new experimental apparatus has been constructed in which film boiling heat transfer can be established in a transparent test section. Data on liquid core stability, core break-up mechanism, and dispersed-core liquid slug and droplet sizes are obtained using F 113 as a test fluid. Both high speed movies and flash photographs are used. The inlet section consists of specially designed coaxial nozzles for gas and liquid such that the ideal inverted annular flow can be generated. The roll wave formation, droplet entrainment from wave crests, agitated sections with large interfacial areas, classical sinuous jet instability, jet break-up into multiple liquid ligaments and drop formation from liquid ligaments have been observed in detail. (orig.)

  17. Molecular Diagnostics for the Study of Hypersonic Flows

    2000-04-01

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO10744 TITLE: Molecular Diagnostics for the Study of Hypersonic Flows...following component part numbers comprise the compilation report: ADP010736 thru ADPO10751 UNCLASSIFIED 5-1 Molecular Diagnostics for the Study of

  18. Experimental study of bubbly flow using image processing techniques

    Fu, Yucheng, E-mail: ycfu@vt.edu; Liu, Yang, E-mail: liu130@vt.edu

    2016-12-15

    This paper presents an experimental study of bubbly flows at relatively high void fractions using an advanced image processing method. Bubble overlapping is a common problem in such flows and the past studies often treat the overlapping bubbles as a whole, which introduces considerable measurement uncertainties. In this study, a hybrid method combining intersection point detection and watershed segmentation is used to separate the overlapping bubbles. In order to reconstruct bubbles from separated segments, a systematic procedure is developed which can preserve more features captured in the raw image compared to the simple ellipse fitting method. The distributions of void fraction, interfacial area concentration, number density and velocity are obtained from the extracted bubble information. High-speed images of air-water bubbly flows are acquired and processed for eight test runs conducted in a 30 mm × 10 mm rectangular channel. The developed image processing scheme can effectively separate overlapping bubbles and the results compare well with the measurements by the gas flow meter and double-sensor conductivity probe. The development of flows in transverse and mainstream directions are analyzed and compared with the prediction made by the one-dimensional interfacial area transport equation (IATE) and the bubble number density transport equation.

  19. Experimental study on combustion characteristics of sodium fire in a columnar flow

    Zhang Zhigang; Peng Kangwei; Guo Ming; Huo Yan

    2014-01-01

    In the operation of the sodium-cooled fast reactor, the accident caused by the leakage and combustion of liquid sodium is common and frequent in sodium-related facilities. This paper is based on an experimental study of sodium fire in a columnar flow, which was carried out to focus on the burning characteristics by analyzing the temperature fields in the burner. The injection of 200°C liquid sodium with the flux of 0.5 m 3 /h was poured into a 7.9 m 3 volume stainless steel cylindrical burner to shape a sodium fire, and the data of temperature fields in the burner have been collected by dozens of thermocouples which are laid in the combustion space and sodium collection plate. These results show that the sodium fire in a columnar flow is composed of the foregoing centered columnar fire, the subsequent spray fire caused by atomization and the pool fire on the collection plate. The temperature close to the burning sodium flow maximally reaches up to 950°C. The radial temperatures apart from the sodium flow are relatively low and generally about 200°C, and maximally just 300°C even when close to the sodium collection plate. The maximum temperature of the burning sodium dropping on the collection plate rises in the center of plate, about 528°C. This study is helpful to evaluate the combustion characteristics, formation process and composing forms of the sodium fire in the sodium-related facilities. (author)

  20. Computational modeling of river flow using bathymetry collected with an experimental, water-penetrating, green LiDAR

    Kinzel, P. J.; Legleiter, C. J.; Nelson, J. M.

    2009-12-01

    Airborne bathymetric Light Detection and Ranging (LiDAR) systems designed for coastal and marine surveys are increasingly being deployed in fluvial environments. While the adaptation of this technology to rivers and streams would appear to be straightforward, currently technical challenges remain with regard to achieving high levels of vertical accuracy and precision when mapping bathymetry in shallow fluvial settings. Collectively these mapping errors have a direct bearing on hydraulic model predictions made using these data. We compared channel surveys conducted along the Platte River, Nebraska, and the Trinity River, California, using conventional ground-based methods with those made with the hybrid topographic/bathymetric Experimental Advanced Airborne Research LiDAR (EAARL). In the turbid and braided Platte River, a bathymetric-waveform processing algorithm was shown to enhance the definition of thalweg channels over a more simplified, first-surface waveform processing algorithm. Consequently flow simulations using data processed with the shallow bathymetric algorithm resulted in improved prediction of wetted area relative to the first-surface algorithm, when compared to the wetted area in concurrent aerial imagery. However, when compared to using conventionally collected data for flow modeling, the inundation extent was over predicted with the EAARL topography due to higher bed elevations measured by the LiDAR. In the relatively clear, meandering Trinity River, bathymetric processing algorithms were capable of defining a 3 meter deep pool. However, a similar bias in depth measurement was observed, with the LiDAR measuring the elevation of the river bottom above its actual position, resulting in a predicted water surface higher than that measured by field data. This contribution addresses the challenge of making bathymetric measurements with the EAARL in different environmental conditions encountered in fluvial settings, explores technical issues related to

  1. The three paradoxes of patient flow: an explanatory case study.

    Kreindler, Sara A

    2017-07-12

    Health systems in many jurisdictions struggle to reduce Emergency Department congestion and improve patient flow across the continuum of care. Flow is often described as a systemic issue requiring a "system approach"; however, the implications of this idea remain poorly understood. Focusing on a Canadian regional health system whose flow problems have been particularly intractable, this study sought to determine what system-level flaws impede healthcare organizations from improving flow. This study drew primarily on qualitative data from in-depth interviews with 62 senior, middle and departmental managers representing the Region, its programs and sites; quantitative analysis of key flow indicators (1999-2012) and review of ~700 documents furnished important context. Examination of the interview data revealed that the most striking feature of the dataset was contradiction; accordingly, a technique of dialectical analysis was developed to examine observed contradictions at successively deeper levels. Analysis uncovered three paradoxes: "Many Small Successes and One Big Failure" (initiatives improve parts of the system but fail to fix underlying system constraints); "Your Innovation Is My Aggravation" (local innovation clashes with regional integration); and most critically, "Your Order Is My Chaos" (rules that improve service organization for my patients create obstacles for yours). This last emerges when some entities (sites/hospitals) define their patients in terms of their location in the system, while others (regional programs) define them in terms of their needs/characteristics. As accountability for improving flow was distributed among groups that thus variously defined their patients, local efforts achieved little for the overall system, and often clashed with each other. These paradoxes are indicative of a fundamental antagonism between the system's parts and the whole. An accretion of flow initiatives in all parts of the system will never add up to a system

  2. A study on the effect of gas flow rate on the wave characteristics in two-phase gas-liquid annular flow

    Han Huawei; Zhu Zhenfeng; Gabriel, Kamiel

    2006-01-01

    Interfacial waves play a very important role in the mass, momentum and energy transport phenomena in annular flow. In this paper, film thickness time-trace measurements for air-water annular flow were collected in a small vertical tube using a parallel wire probe. Using the data, a typical disturbance wave shape was obtained and wave properties (e.g., width, height, speed and roughness) were presented. The liquid mass flux ranged from 100 to 200 kg/m 2 s and the gas mass flux ranged from 18 to 47 kg/m 2 s. Disturbance wave characteristics were defined and the effects of changing the gas flow rate on the wave spacing, wave width, wave peak height and wave base height were studied. An average velocity model for the wave and base regions has been developed to determine the wave velocity. The investigation method could be further extended to annular-mist flow which frequently occurs in boiling water reactors

  3. Substance flow analysis in Finland - Four case studies on N and P flows

    Antikainen, R.

    2007-07-01

    Nitrogen (N) and phosphorus (P) are essential elements for all living organisms. However, in excess, they contribute to such environmental problems as aquatic and terrestrial eutrophication (N, P), acidification (N), global warming (N), groundwater pollution (N), depletion of stratospheric ozone (N), formulation of tropospheric ozone (N) and poor urban air quality (N). Globally, human action has multiplied the volume of N and P cycling since the onset of industrialization. Themultiplication is a result of intensified agriculture, increased energy consumption and population growth. Industrial ecology (IE) is a discipline, in which human interaction with the ecosystems is investigated using a systems analytical approach. The main idea behind IE is that industrial systems resemble ecosystems, and, like them, industrial systems can then be described using material, energy and information flows and stocks. Industrial systems are dependent on the resources provided by the biosphere, and these two cannot be separated from each other. When studying substance flows, the aims of the research from the viewpoint of IE can be, for instance, to elucidate the ways how the cycles of a certain substance could be more closed and how the flows of a certain substance could be decreased per unit of production (= dematerialization). IE uses analytical research tools such as material and substance flow analysis (MFA, SFA), energy flow analysis (EFA), life cycle assessment (LCA) and material input per service unit (MIPS). In Finland, N and P are studied widely in different ecosystems and environmental emissions. A holistic picture comparing different societal systems is, however, lacking. In this thesis, flows of N and P were examined in Finland using SFA in the following four subsystems: (I) forest industry and use of wood fuels, II) food production and consumption, III) energy, and IV) municipal waste. A detailed analysis at the end of the 1990s was performed. Furthermore, historical

  4. Collective flow measurements with HADES in Au+Au collisions at 1.23A GeV

    Kardan, Behruz; Hades Collaboration

    2017-11-01

    HADES has a large acceptance combined with a good mass-resolution and therefore allows the study of dielectron and hadron production in heavy-ion collisions with unprecedented precision. With the statistics of seven billion Au-Au collisions at 1.23A GeV recorded in 2012, the investigation of higher-order flow harmonics is possible. At the BEVALAC and SIS18 directed and elliptic flow has been measured for pions, charged kaons, protons, neutrons and fragments, but higher-order harmonics have not yet been studied. They provide additional important information on the properties of the dense hadronic medium produced in heavy-ion collisions. We present here a high-statistics, multidifferential measurement of v1 and v2 for protons in Au+Au collisions at 1.23A GeV.

  5. A numerical study of blood flow using mixture theory.

    Wu, Wei-Tao; Aubry, Nadine; Massoudi, Mehrdad; Kim, Jeongho; Antaki, James F

    2014-03-01

    In this paper, we consider the two dimensional flow of blood in a rectangular microfluidic channel. We use Mixture Theory to treat this problem as a two-component system: One component is the red blood cells (RBCs) modeled as a generalized Reiner-Rivlin type fluid, which considers the effects of volume fraction (hematocrit) and influence of shear rate upon viscosity. The other component, plasma, is assumed to behave as a linear viscous fluid. A CFD solver based on OpenFOAM ® was developed and employed to simulate a specific problem, namely blood flow in a two dimensional micro-channel, is studied. Finally to better understand this two-component flow system and the effects of the different parameters, the equations are made dimensionless and a parametric study is performed.

  6. Numerical Studies of a Fluidic Diverter for Flow Control

    Gokoglu, Suleyman A.; Kuczmarski, Maria A.; Culley, Dennis E.; Raghu, Surya

    2009-01-01

    The internal flow structure in a specific fluidic diverter is studied over a range from low subsonic to sonic inlet conditions by a time-dependent numerical analysis. The understanding will aid in the development of fluidic diverters with minimum pressure losses and advanced designs of flow control actuators. The velocity, temperature and pressure fields are calculated for subsonic conditions and the self-induced oscillatory behavior of the flow is successfully predicted. The results of our numerical studies have excellent agreement with our experimental measurements of oscillation frequencies. The acoustic speed in the gaseous medium is determined to be a key factor for up to sonic conditions in governing the mechanism of initiating the oscillations as well as determining its frequency. The feasibility of employing plasma actuation with a minimal perturbation level is demonstrated in steady-state calculations to also produce oscillation frequencies of our own choosing instead of being dependent on the fixed-geometry fluidic device.

  7. Radionuclide study on hepatic blood flow in Schistosomiasis Japonica

    Okada, Junichi; Uchiyama, Guio; Hayakawa, Kazushige; Hayashi, Sanshin; Araki, Tsutomu; Arai, Takao; Iuchi, Masahiko

    1986-11-01

    Schistosomiasis Japonica is a regional disease found in elderly people who were living in once-endemic areas in Japan. Yamanashi was one of these areas until 1970, since when no newly infected patients were reported. The disease is characteristic of developing irreversible interstitial fibrosis of the liver, where parasites migrate and lay eggs. Portal hypertension, esophageal varices and hepatocellular carcinomas are the common features of the results. In order to estimate patient's hepatic blood flow, radionuclide angiography of the liver with the use of 10 - 15 millicuries of Tc-99m phytate were performed prior to the conventional multiview imaging. Twenty-two patients with schistosomiasis and twelve adults without evidence of liver disease were studied. A time-activity curve of the right lobe of the liver was generated by a computer, and the ratio of arterial blood flow to portal blood flow was calculated. As a result, a good correlation was found between the arterial to portal blood flow ratio and the grade of hepatic fibrosis verified by laparoscopic biopsy. The development of esophageal varices were likely to correlate well with the blood flow ratio rather than scores on the conventional static liver and spleen scintigram. The study was useful for evaluating patient's clinical stages and prognosis.

  8. Radionuclide study on hepatic blood flow in Schistosomiasis Japonica

    Okada, Junichi; Uchiyama, Guio; Hayakawa, Kazushige; Hayashi, Sanshin; Araki, Tsutomu; Arai, Takao; Iuchi, Masahiko.

    1986-01-01

    Schistosomiasis Japonica is a regional disease found in elderly people who were living in once-endemic areas in Japan. Yamanashi was one of these areas until 1970, since when no newly infected patients were reported. The disease is characteristic of developing irreversible interstitial fibrosis of the liver, where parasites migrate and lay eggs. Portal hypertension, esophageal varices and hepatocellular carcinomas are the common features of the results. In order to estimate patient's hepatic blood flow, radionuclide angiography of the liver with the use of 10 - 15 millicuries of Tc-99m phytate were performed prior to the conventional multiview imaging. Twenty-two patients with schistosomiasis and twelve adults without evidence of liver disease were studied. A time-activity curve of the right lobe of the liver was generated by a computer, and the ratio of arterial blood flow to portal blood flow was calculated. As a result, a good correlation was found between the arterial to portal blood flow ratio and the grade of hepatic fibrosis verified by laparoscopic biopsy. The development of esophageal varices were likely to correlate well with the blood flow ratio rather than scores on the conventional static liver and spleen scintigram. The study was useful for evaluating patient's clinical stages and prognosis. (author)

  9. Study of Collective Effects in the FCC-ee Collider

    Zobov, Mikhail; Belli, Eleonora; Castorina, Giovanni; Migliorati, Mauro; Persichelli, Serena; Rumolo, Giovanni; Spataro, Bruno

    2018-01-01

    The Future Circular Collider (FCC) study aims at designing different options of a post-LHC collider. The high luminosity electron-positron collider FCC-ee based on the crab waist concept is considered as an intermediate step on the way towards FCC-hh, a 100 TeV hadron collider using the same tunnel of about 100 km. Due to a high intensity of circulating beams the impact of collective effects on FCC-ee performance has to be carefully analyzed. In this paper we evaluate beam coupling impedance ...

  10. Microscopic calculations of nuclear matter collective flow in Nb(400 MeV/N) + Nb

    Hoffer, J.B.; Kruse, H.; Molitoris, J.J.; Stoecker, H.

    1984-01-01

    The recent experimental observation of sidewards peaks in the emission pattern of fragments emitted in collisions of heavy nuclear systems has stimulated a dispute among theorists about how to interpret these data. It has been shown that the observations are in agreement with the results of macroscopic nuclear fluid dynamical calculations, but several microscopic calculations done to simulate the sidewards emission (via the intranuclear cascade (INC) approach) failed - the angular distributions obtained where always forward peaked. A many body equations of motion (EOM) approach to study heavy ion collision has been developed. The approach is analogous to the early work of Bodmer et al., and Wilets et al. Hamilton's equations of motion are solved for an ensemble of nucleons with simultaneous mutual two-body interactions between all particles. The model predicts the sidewards emission peaks for the Nb + Nb reaction

  11. Experimental study of vortex breakdown in a cylindrical, swirling flow

    Stevens, J. L.; Celik, Z. Z.; Cantwell, B. J.; Lopez, J. M.

    1996-01-01

    The stability of a steady, vortical flow in a cylindrical container with one rotating endwall has been experimentally examined to gain insight into the process of vortex breakdowwn. The dynamics of the flow are governed by the Reynolds number (Re) and the aspect ratio of the cylinder. Re is given by Omega R(sup 2)/nu, where Omega is the speed of rotation of the endwall, R is the cylinder radius, and nu is the kinematic viscosity of the fluid filling the cylinder. The aspect ratio is H/R, where H is the height of the cylinder. Numerical simulation studies disagree whether or not the steady breakdown is stable beyond a critical Reynolds number, Re(sub c). Previous experimental researches have considered the steady and unsteady flows near Re(sub c), but have not explored the stability of the steady breakdown structures beyond this value. In this investigation, laser induced fluorescence was utilized to observe both steady and unsteady vortex breakdown at a fixed H/R of 2.5 with Re varying around Re(sub c). When the Re of a steady flow was slowly increased beyond Re(sub c), the breakdown structure remained steady even though unsteadiness was possible. In addition, a number of hysteresis events involving the oscillation periods of the unsteady flow were noted. The results show that both steady and unsteady vortex breakdown occur for a limited range of Re above Re(sub c). Also, with increasing Re, complex flow transformations take place that alter the period at which the unsteady flow oscillates.

  12. Numerical study of free pulsed jet flow with variable density

    Kriaa, Wassim [Laboratoire de Mecanique des Fluides et Thermique, Ecole Nationale d' Ingenieurs de Monastir, Route de Ouardanine, 5000 Monastir (Tunisia)], E-mail: kriaawass@yahoo.fr; Cheikh, Habib Ben; Mhiri, Hatem [Laboratoire de Mecanique des Fluides et Thermique, Ecole Nationale d' Ingenieurs de Monastir, Route de Ouardanine, 5000 Monastir (Tunisia); Le Palec, Georges; Bournot, Philippe [Institut de Mecanique de Marseille, 60 rue Juliot Curie Technopole de Chateau-Gombert 13453, Marseille Cedex 13 (France)

    2008-05-15

    In this work, we propose a numerical study of a free pulsed plane jet with variable density in unsteady and laminar modes. At the nozzle exit, the flow is characterized by a uniform temperature and submitted to a longitudinal and periodic velocity disturbance: u = u{sub 0}(1 + A sin({omega}t)). A finite difference method is performed to solve the equations governing this flow type. The discussion relates to the effect of the most significant parameters, such as the pulsation frequency and amplitude, on the flow characteristic fields. The effects of Reynolds and Galileo numbers was also examined. The results show that the pulsation affects the flow in the vicinity of the nozzle, and further, the results of the unsteady mode join those of the steady non-pulsed jet. The results state also that the Strouhal number has no influence on the flow mixture degree, whereas the amplitude of pulsation affects, in a remarkable way, the mixture and, consequently, the concentration core length.

  13. A fundamental study of a variable critical nozzle flow

    Kim, Jea Hyung; Kim, Heuy Dong; Park, Kyung Am

    2003-01-01

    The mass flow rate of gas flow through critical nozzle depends on the nozzle supply conditions and the cross-sectional area at the nozzle throat. In order that the critical nozzle can be operated at a wide range of supply conditions, the nozzle throat diameter should be controlled to change the flow passage area. This can be achieved by means of a variable critical nozzle. In the present study, both experimental and computational works are performed to develop variable critical nozzle. A cone-cylinder with a diameter of d is inserted into conventional critical nozzle. It can move both upstream and downstream, thereby changing the cross-sectional area of the nozzle throat. Computational work using the axisymmetric, compressible Navier-Stokes equations is carried out to simulate the variable critical nozzle flow. An experiment is performed to measure the mass flow rate through variable critical nozzle. The present computational results are in close agreement with measured ones. The boundary layer displacement and momentum thickness are given as a function of Reynolds number. An empirical equation is obtained to predict the discharge coefficient of variable critical nozzle

  14. A study of the flow field surrounding interacting line fires

    Trevor Maynard; Marko Princevac; David R. Weise

    2016-01-01

    The interaction of converging fires often leads to significant changes in fire behavior, including increased flame length, angle, and intensity. In this paper, the fluid mechanics of two adjacent line fires are studied both theoretically and experimentally. A simple potential flow model is used to explain the tilting of interacting flames towards each other, which...

  15. A comparative study of the flow enhancing properties of bentonite ...

    A comparative study of granule flow enhancing property of bentonite, magnesium stearate, talc and microcrystalline cellulose (MCC) was undertaken. Bentonite was processed into fine powder. A 10 %w/w of starch granules was prepared and separated into different sizes (˂180, 180-500, 500-710 and 710-850 μm).

  16. Flow and performance: a study among talented Dutch soccer players

    Bakker, A.B.; Oerlemans, Wido; Demerouti, E.; Bruins Slot, B.; Karamat Ali, D.

    2011-01-01

    Objective: The present study examines the relationship between environmental resources (autonomy,social support from the coach, and performance feedback), flow, and performance among young talented soccer players. Design: The design was non-experimental and involved both self- and coach-rated

  17. Technetium-99m DTPA renal flow studies in Goldblatt hypertension

    Nally, J.V.; Clarke, H.S.; Windham, J.P.; Grecos, G.P.; Gross, M.L.; Potvin, W.J.

    1985-01-01

    Computer-assisted dynamic renal studies were performed on a group of 14 mongrel dogs before and after the induction of unilateral renal artery stenosis. Ninety-second technetium-99m diethylenetriaminepentaacetic acid ([/sup 99m/Tc]DTPA), 15-min [/sup 99m/Tc]DTPA, and 30-min iodine-131 orthoiodohippurate ([ 131 I]hippuran) time-activity curves were analyzed and correlated with reduction of renal blood flow as measured by electromagnetic flow probe and PAH clearance techniques. For blood flow reductions greater than 33%, the [/sup 99m/Tc]DTPA studies were judged diagnostic of unilateral renal artery stenosis in all cases, whereas the [ 131 I]hippuran time-activity curves were indicative of stenosis in only six of ten studies. Thus, in this model we find the computer-assisted 90-sec [/sup 99m/Tc]DTPA renal flow study to be superior to conventional [ 131 I]hippuran renography in the diagnosis of moderate-to-serve unilateral renal artery stenosis

  18. Simulation and experimental study of resin flow in fibre fabrics

    Yan, Fei; Yan, Shilin; Li, Yongjing

    2017-06-01

    Liquid Composite Moulding (LCM) is gradually becoming the most competitive manufacturing technology for producing large composite parts with complex geometry with high quality and low cost. These parts include those for airplanes, wind turbine blades and automobile components. Fibre fabrics in liquid composite moulding can be considered as dual-scale porous media. In different gap scales, an unsaturated flow is produced during the mould filling process. This particular flow behaviour deviates from the traditional Darcy’s law, which is used to calculate the filling pressure and will cause errors. According to sink theory, the unsaturated flow characteristics of this dual-scale porous media were studied in this paper, and a FEM solution program was developed. The results showed that the pressure curves against the position which simulated by sink functions were departure from the position of traditional theory. In addition, the simulation results of partially-saturated region were consistent with the experimental data.

  19. A Study of the Flow Field Surrounding Interacting Line Fires

    Trevor Maynard

    2016-01-01

    Full Text Available The interaction of converging fires often leads to significant changes in fire behavior, including increased flame length, angle, and intensity. In this paper, the fluid mechanics of two adjacent line fires are studied both theoretically and experimentally. A simple potential flow model is used to explain the tilting of interacting flames towards each other, which results from a momentum imbalance triggered by fire geometry. The model was validated by measuring the velocity field surrounding stationary alcohol pool fires. The flow field was seeded with high-contrast colored smoke, and the motion of smoke structures was analyzed using a cross-correlation optical flow technique. The measured velocities and flame angles are found to compare reasonably with the predicted values, and an analogy between merging fires and wind-blown flames is proposed.

  20. Study of the flow development of polymer solutions through capillaries

    Perez-Gonzalez, J.; De Vargas, L.; Tejero, M.

    1991-01-01

    Flow experiments through capillaries with semirigid and rigid polymers in aqueous solutions were carried out in order to study the dependence of the flow development on the molecular conformation and the length to diameter ratio (L/D), of the capillary at relatively low shear rates. It was found that the apparent viscosity has a strong dependence upon the ratio L/D for a given shear rate, although an asymptotic value is reached. This dependence was reflected in the non-linearity of Bagley's plots. The asymptotic value was attained at lower L/D values for semirigid molecules than for rigid ones, showing the influence of the molecular conformation on the flow field development due to the different modes of relaxation for each type of molecule. (Author)

  1. Hydrodynamics of adiabatic inverted annular flow: an experimental study

    De Jarlais, G.; Ishii, M.

    1983-01-01

    For low-quality film boiling in tubes or rod bundles, the flow pattern may consist of a liquid jet-like core surrounded by a vapor annulus, i.e., inverted annular flow. The stability, shape, and break-up mechanisms of this liquid core must be understood in order to model correctly this regime and to develop appropriate interfacial transfer correlations. This paper reports on a study in which inverted annular flow was simulated in an adiabatic system. Turbulent water jets, issuing downward from long-aspect nozzles were enclosed within cocurrent gas annuli. Jet-core diameter and velocity, and gas-annulus diameter, velocity, and species were varied, yielding liquid Reynolds numbers up to 33,000, void fractions from 0.29 to 0.95, and relative velocities from near zero to over 80 m/s. Jet-core break-up lengths and secondarily, core break-up mechanisms, were observed visually, using strobe lighting

  2. Experimental and theoretical studies of buoyant-thermo capillary flow

    Favre, E.; Blumenfeld, L.; Soubbaramayer

    1996-01-01

    In the AVLIS process, uranium metal is evaporated using a high power electron gun. We have prior discussed the power balance equation in the electron beam evaporation process and pointed out, among the loss terms, the importance of the power loss due to the convective flow in the molten pool driven by buoyancy and thermo capillarity. An empirical formula has been derived from model experiments with cerium, to estimate the latter power loss and that formula can be used practically in engineering calculations. In order to complete the empirical approach, a more fundamental research program of theoretical and experimental studies have been carried out in Cea-France, with the objective of understanding the basic phenomena (heat transport, flow instabilities, turbulence, etc.) occurring in a convective flow in a liquid layer locally heated on its free surface

  3. Acoustics advances study of sea floor hydrothermal flow

    Rona, Peter A.; Jackson, Darrell R.; Bemis, Karen G.; Jones, Christopher D.; Mitsuzawa, Kyohiko; Palmer, David R.; Silver, Deborah

    Sub-sea floor hydrothermal convection systems discharge as plumes from point sources and as seepage from the ocean bottom. The plumes originate as clear, 150-400°C solutions that vent from mineralized chimneys; precipitate dissolved metals as particles to form black or white smokers as they turbulently mix with ambient seawater; and buoyantly rise hundreds of meters to a level of neutral density where they spread laterally. The seepage discharges from networks of fractures at the rock-water interface as clear, diffuse flow, with lower temperatures, metal contents, and buoyancy than the smokers. The diffuse flow may be entrained upward into plumes, or laterally by prevailing currents in discrete layers within tens of meters of the sea floor. The role of these flow regimes in dispersing heat, chemicals, and biological material into the ocean from sub-sea floor hydrothermal convection systems is being studied on a global scale.

  4. Computational Studies on the Performance of Flow Distributor in Tank

    Shin, Soo Jai; Kim, Young In; Ryu, Seungyeob; Bae, Youngmin

    2014-01-01

    Core make-up tank (CMT) is full of borated water and provides makeup and boration to the reactor coolant system (RCS) for early stage of loss of coolant accident (LOCA) and non-LOCA. The top and bottom of CMT are connected to the RCS through the pressure balance line (PBL) and the safety injection line (SIL), respectively. Each PBL is normally open to maintain pressure of the CMT at RCS, and this arrangement enables the CMT to inject water to the RCS by gravity when the isolation valves of SIL are open. During CMT injection into the Reactor, the condensation and thermal stratification are observed in CMT and the rapid condensation disturbed the injection operation. The optimal design of the flow distributor is very important to ensure structural integrity of the reactor system and their safe operation during some transient or accident conditions. In the present study, we numerically investigated the performance of flow distributor in tank with different shape factor such as the total number of the holes, the pitch-to-hole diameter ratios (p/d), the diameter of the hole and the area ratios. These data will contribute to the design the flow distributor. In the present study, the model of the flow distributor in tank is simulated using the commercial CFD software, Fluent 13.0 with varying the different shape factor of the flow distributor such as the total number of the holes, the diameter of the holes and the area ratio. As the diameter of the hole is smaller, the velocity difference between holes, which is located at upper position and lower position of the flow distributor, also decreases. For larger area ratio, the velocity of the holes is slower. When the diameter of the hole is large enough for the velocity difference between holes to be large, however, the velocity of the holes is not in inverse proportional to the area ratio

  5. Computational Studies on the Performance of Flow Distributor in Tank

    Shin, Soo Jai; Kim, Young In; Ryu, Seungyeob; Bae, Youngmin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Core make-up tank (CMT) is full of borated water and provides makeup and boration to the reactor coolant system (RCS) for early stage of loss of coolant accident (LOCA) and non-LOCA. The top and bottom of CMT are connected to the RCS through the pressure balance line (PBL) and the safety injection line (SIL), respectively. Each PBL is normally open to maintain pressure of the CMT at RCS, and this arrangement enables the CMT to inject water to the RCS by gravity when the isolation valves of SIL are open. During CMT injection into the Reactor, the condensation and thermal stratification are observed in CMT and the rapid condensation disturbed the injection operation. The optimal design of the flow distributor is very important to ensure structural integrity of the reactor system and their safe operation during some transient or accident conditions. In the present study, we numerically investigated the performance of flow distributor in tank with different shape factor such as the total number of the holes, the pitch-to-hole diameter ratios (p/d), the diameter of the hole and the area ratios. These data will contribute to the design the flow distributor. In the present study, the model of the flow distributor in tank is simulated using the commercial CFD software, Fluent 13.0 with varying the different shape factor of the flow distributor such as the total number of the holes, the diameter of the holes and the area ratio. As the diameter of the hole is smaller, the velocity difference between holes, which is located at upper position and lower position of the flow distributor, also decreases. For larger area ratio, the velocity of the holes is slower. When the diameter of the hole is large enough for the velocity difference between holes to be large, however, the velocity of the holes is not in inverse proportional to the area ratio.

  6. Harvesting Collective Trend Observations from Large Scale Study Trips

    Eriksen, Kaare; Ovesen, Nis

    2014-01-01

    To enhance industrial design students’ decoding and understanding of the technological possibilities and the diversity of needs and preferences in different cultures it is not unusual to arrange study trips where such students acquire a broader view to strengthen their professional skills and app...... numbers of students to the annual Milan Design Week and the Milan fair ‘I Saloni’ in Italy. The present paper describes and evaluates the method, the theory behind it, the practical execution of the trend registration, the results from the activities and future perspectives....... and approach, hence linking the design education and the design culture of the surrounding world. To improve the professional learning it is useful, though, to facilitate and organize the trips in a way that involves systematic data collection and reporting. This paper presents a method for facilitating study...

  7. Experimental study on flow pattern and heat transfer of inverted annular flow

    Takenaka, Nobuyuki; Akagawa, Koji; Fujii, Terushige; Nishida, Koji

    1990-01-01

    Experimental results are presented on flow pattern and heat transfer in the regions from inverted annular flow to dispersed flow in a vertical tube using freon R-113 as a working fluid at atmospheric pressure to discuss the correspondence between them. Axial distributions of heat transfer coefficient are measured and flow patterns are observed. The heat transfer characteristics are divided into three regions and a heat transfer characteristics map is proposed. The flow pattern changes from inverted annular flow (IAF) to dispersed flow (DF) through inverted slug flow (ISF) for lower inlet velocities and through agitated inverted annular flow (AIAF) for higher inlet velocities. A flow pattern map is obtained which corresponds well with the heat transfer characteristic map. (orig.)

  8. Flow Reactor for studying Physicochemical and aging properties of SOA

    Babar, Z. B.

    2016-12-01

    Secondary organic aerosols (SOA) have importance in environmental processes such as affecting earth's radiative balance and cloud formation processes. For studying SOA formation large scale environmental batch reactors and laboratory scale flow reactors have been used. In this study application of flow reactor to study physicochemical properties of SOA is also investigated after its characterization. The flow reactor is of cylindrical design (ID 15 cm x L 70 cm) equipped with UV lamps. It is coupled with various instruments such as scanning mobility particle sizer, NOx analyzer, ozone analyzer, VOC analyzer, hygrometer, and temperature sensors for gas and particle phase measurements. OH radicals were generated by custom build ozone generator and relative humidity. The following characterizations were performed: (1) residence time distribution (RTD) measurements, (2) RH and temperature control, (3) OH radical exposure range (atmospheric aging time), (4) gas phase oxidation of SOA precursors such as α-pinene by OH radical. The flow reactor yielded narrow RTDs. In particular, RH and temperature can be controlled effectively between 0-60% and 22-43oC, respectively. OH radical exposure ranges from 6.49x1010 to 3.68x1011 molecules/cm3s (0.49 to 4.91 days). Our initial efforts on OH radical generation using hydrogen peroxide and its quantification by using flourescenet technique will be also be presented.

  9. Flow visualization study of inverted annular flow of post dryout heat transfer region

    Ishii, M.; De Jarlais, G.

    1985-01-01

    The inverted annular flow is important in the area of LWR accident analysis in terms of the maximum cladding temperature and effectiveness of the emergency core cooling. However, the inverted annular flow thermal-hydraulics is not well understood due to its special heat transfer condition of film boiling. The review of existing data indicates further research is needed in the areas of basic hydrodynamics related to liquid core disintegration mechanisms, slug and droplet formation, entrainment, and droplet size distributions. In view of this, the inverted flow is studied in detail experimentally. A new experimental apparatus has been constructed in which film boiling heat transfer can be established in a transparent test section. The test section consists of two coaxial quartz tubes. The annular gap between these two tubes is filled with a hot, clear fluid (syltherm 800) so as to maintain film boiling temperatures and heat transfer rates at the inner quartz tube wall. Data on liquid core stability, core break-up mechanism, and dispersed-core liquid slug and droplet sizes are obtained using F 113 as a test fluid. Both high speed movies and flash photographs (3 μsec) are used

  10. Experimental study of static flow instability in subcooled flow boiling in parallel channels

    Siman-Tov, M.; Felde, D.K.; McDuffee, J.L.; Yoder, G.L.

    1995-01-01

    Experimental data for static flow instability or flow excursion (FE) at conditions applicable to the Advanced Neutron Source Reactor are very limited. A series of FE tests with light water flowing vertically upward was completed covering a local exit heat flux range of 0.7--18 MW/m 2 , exit velocity range of 2.8--28.4 m/s, exit pressure range of 0.117--1.7 MPa, and inlet temperature range of 40-- 50 degrees C. Most of the tests were performed in a ''stiff'' (constant flow) system where the instability threshold was detected through the minimum of the pressure-drop curve. A few tests were also conducted using as ''soft'' (constant pressure drop) a system as possible to secure a true FE phenomenon (actual secondary burnout). True critical heat flux experiments under similar conditions were also conducted using a stiff system. The FE data reported in this study considerably extend the velocity range of data presently available worldwide, most of which were obtained at velocities below 10 m/s. The Saha and Zuber correlation had the best fit with the data out of the three correlations compared. However, a modification was necessary to take into account the demonstrated dependence of the St and Nu numbers on subcooling levels, especially in the low subcooling regime. Comparison of Thermal Hydraulic Test Loop (THTL) data, as well as extensive data from other investigators, led to a proposed modification to the Saha and Zuber correlation for onset of significant void, applied to FE prediction. The mean and standard deviation of the THTL data were 0.95 and 15%, respectively, when comparing the THTL data with the original Saha and Zuber correlation, and 0.93 and 10% when comparing them with the modification. Comparison with the worldwide database showed a mean and standard deviation of 1.37 and 53%, respectively, for the original Saha and Zuber correlation and 1.0 and 27% for the modification

  11. ESF collection effectiveness, a study in fine particle dynamics

    Winegardner, W.K.; Owczarski, P.C.

    1985-04-01

    The characterization and dynamic behavior of fine particles are the main subjects of an ongoing investigation of the particle collection effectiveness of the engineered safety feature (ESF) systems in nuclear power plants. This investigation is part of a larger study of the release of radionuclides to the environment from such plants during postulated accidents that are severe but extremely unlikely. The ESF systems are installed to prevent the occurrence of severe accidents or mitigate their consequences. Several of these engineered systems can serve as particle collection devices. This report focuses on the analytical models that were developed to predict particle behavior in two systems that were not specifically designed for particle retention: the ice compartments of ice condenser containment systems in Pressurized Water Reactors (PWRs) and the suppression pools of Boiling Water Reactors (BWRs). The following section summarizes the topics considered in the development of models and computer codes for estimating the particle retention effectiveness of these two ESF systems. After the summary this paper describes the two ESF systems in more detail and discusses the behavior of particles in both situations

  12. Data collection in Internet environment in social representations studies

    Aline Vieira De Lima Nunes

    2011-01-01

    Full Text Available The present study aimed at comparing social representations structures concerning data collection procedures: through internet forms, diffused in the WWW, and through conventional paper and pencil questionnaire methods. O verall 893 individuals participated in the research, 58% of whom were female. A total of 217 questionnaires about the social representation on football (soccer and 218 about the representation on aging were answered by Brazilian university students in classrooms. Electronic versions of the same instrument were diffused through an internet forum linked to the same university. There were 238 answers for the football questionnaire and 230 for the aging one. The instrument asked participants to indicate five wordsor expressions related to one of the social objects. Sample characteristics and structural analyses were carried out separately for the two data collection procedures. Data indicated that internet-based research allows for higher sample diversity, but it is essential to guarantee the adoption of measures that can select only desired participants. Results also pointed out the need to take into account the nature of the social object to be investigated through internet research on representations, seeking to avoid self-selection effects, which can bias results, as it seems to have happened with the football social object.

  13. Experimental study of interfacial wave on a liquid film in vertical annular flow

    Hazuku, T.; Fukamachi, N.; Takamasa, T.; Matsumoto, Y.

    2003-01-01

    In this study, a precise database of microscopic interfacial wave-structure for annular flow developing in a vertical pipe was obtained using a new measuring technique with a laser focus displacement meter. Adiabatic upward annular air-water flow experiments were conducted using a 3-m-long, 11- mm-ID pipe. Measurements of interfacial waves were conducted at 21 axial locations, spaced 110 mm apart, in the pipe. The axial distances from the inlet (L) normalized by the pipe diameter (D) varied over L/D = 50 to 250. Data were collected for predetermined gas and liquid flow conditions and for Reynolds numbers ranging from Reg = 31,800 to 98,300 for the gas phase and Ref = 1,050 to 9,430 for the liquid phase. Using this new technique, we obtained such local properties as the minimum thickness, maximum thickness, and passing frequency of the waves. The results revealed that the maximum film thickness and passing frequency of disturbance waves decreased gradually, with some oscillations, as flow developed. The flow development, i.e., decreases of film thickness and passing frequency, existed until the pipe exit, which means that the flow might never reach a fully developed condition. Minimum thickness of the film decreased with flow development and with increasing gas flow rate. These results are discussed, taking into account the buffer layer calculated from Karman's three-layer model. Correlation is proposed for the minimum film thickness obtained in regard to interfacial shear stress and the Reynolds number of the liquid. This correlation expresses the minimum film thickness obtained from the experiment within a 5% deviation

  14. Zebrafish swimming in the flow: a particle image velocimetry study

    Violet Mwaffo

    2017-11-01

    Full Text Available Zebrafish is emerging as a species of choice for the study of a number of biomechanics problems, including balance development, schooling, and neuromuscular transmission. The precise quantification of the flow physics around swimming zebrafish is critical toward a mechanistic understanding of the complex swimming style of this fresh-water species. Although previous studies have elucidated the vortical structures in the wake of zebrafish swimming in placid water, the flow physics of zebrafish swimming against a water current remains unexplored. In an effort to illuminate zebrafish swimming in a dynamic environment reminiscent of its natural habitat, we experimentally investigated the locomotion and hydrodynamics of a single zebrafish swimming in a miniature water tunnel using particle image velocimetry. Our results on zebrafish locomotion detail the role of flow speed on tail beat undulations, heading direction, and swimming speed. Our findings on zebrafish hydrodynamics offer a precise quantification of vortex shedding during zebrafish swimming and demonstrate that locomotory patterns play a central role on the flow physics. This knowledge may help clarify the evolutionary advantage of burst and cruise swimming movements in zebrafish.

  15. Developing the technique of image processing for the study of bubble dynamics in subcooled flow boiling

    Donevski, Bozin; Saga, Tetsuo; Kobayashi, Toshio; Segawa, Shigeki

    1998-01-01

    This study presents the development of an image processing technique for studying the dynamic behavior of vapor bubbles in a two-phase bubbly flow. It focuses on the quantitative assessment of some basic parameters such as a local bubble size and size distribution in the range of void fraction between 0.03 < a < 0.07. The image processing methodology is based upon the computer evaluation of high speed motion pictures obtained from the flow field in the region of underdeveloped subcooled flow boiling for a variety of experimental conditions. This technique has the advantage of providing computer measurements and extracting the bubbles of the two-phase bubbly flow. This method appears to be promising for determining the governing mechanisms in subcooled flow boiling, particularly near the point of net vapor generation. The data collected by the image analysis software can be incorporated into the new models and computer codes currently under development which are aimed at incorporating the effect of vapor generation and condensation separately. (author)

  16. Evaluation of Salivary Glucose, IgA and Flow Rate in Diabetic Patients: A Case-Control Study

    Bakianian Vaziri, P.; Vahedi, M.; Mortazavi, H.; Abdollahzadeh, Sh.; Hajilooi, M.

    2010-01-01

    Objective: An association between diabetes mellitus and alterations in the oral cavity has been noted. In this study, we evaluated differences between salivary IgA, glucose and flow rate in diabetic patients compared with healthy controls. Materials and Methods: Forty patients with type 1 diabetes, 40 patients with type 2 diabetes and 40 healthy controls were selected. Whole unstimulated saliva samples were collected by the standard method and the salivary flow rate was determined. Nephelomet...

  17. Experimental study on flow pattern transitions for inclined two-phase flow

    Kwak, Nam Yee; Lee, Jae Young [Handong Univ., Pohang (Korea, Republic of); Kim, Man Woong [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2007-07-01

    In this paper, experimental data on flow pattern transition of inclination angles from 0-90 are presented. A test section is constructed 2 mm long and I.D 1inch using transparent material. The test section is supported by aluminum frame that can be placed with any arbitrary inclined angles. The air-water two-phase flow is observed at room temperature and atmospheric condition using both high speed camera and void impedance meter. The signal is sampled with sampling rate 1kHz and is analyzed under fully-developed condition. Based on experimental data, flow pattern maps are made for various inclination angles. As increasing the inclination angels from 0 to 90, the flow pattern transitions on the plane jg-jf are changed, such as stratified flow to plug flow or slug flow or plug flow to bubbly flow. The transition lines between pattern regimes are moved or sometimes disappeared due to its inclined angle.

  18. Eye wash water flow direction study: an evaluation of the effectiveness of eye wash devices with opposite directional water flow.

    Fogt, Jennifer S; Jones-Jordan, Lisa A; Barr, Joseph T

    2018-01-01

    New designs of eye wash stations have been developed in which the direction of water flow from the fountain has been reversed, with two water streams originating nasally in both eyes and flowing toward the temporal side of each eye. No study has been done to determine the ideal direction of water flow coming from the eye wash in relation to the eye. Ophthalmic eye examinations were conducted before and after the use of two eye wash stations with opposite water flow directionality. Fluorescein was instilled in both eyes before using an eye wash to measure the effectiveness of the water flow. Subjects were surveyed upon their experiences using the eye washes. Ophthalmic examination found no significant difference in the efficacy of the eye washes with nasal-to-temporal water flow when compared to temporal-to-nasal water flow direction.

  19. Studies on the crossed flow type MHD turbines

    Hori, Toshihiro; Katsurai, Makoto

    1981-01-01

    The studies on crossed flow type MHD turbines were performed to improve its characteristics. Two-dimensional models were considered for the analytical studies. To compensate the edge effect of magnetic field, the magnetic field gradient by tapering was considered. An iron-core structure and an air-core structure were investigated. It was found that the ideal characteristics can be obtained when there is the tapered length more than one wave length. Various methods for the improvement of magnetic field were studied in the case of practical crossed flow type MHD turbines. The methods were the adjustment with an iron-core, and the adoption of a curved channel. It can be expected to obtain the internal efficiency of more than 70 percent, when the number of pole-pairs is more than 10 and the radius of curvature of a few times of rotor radius is given to a curved channel. (Kato, T.)

  20. Flow visualization study of post critical heat flux region for inverted bubbly, slug and annular flow regimes

    Denten, J.G.; Ishii, M.

    1988-11-01

    A visual study of film boiling using still photographic and high- speed motion picture methods was carried out in order to analyze the post-CHF hydrodynamics for steady-state inlet pre-CHF two-phase flow regimes. Pre-CHF two-phase flow regimes were established by introducing Freon 113 liquid and nitrogen gas into a jet core injection nozzle. An idealized, post-CHF two-phase core initial flow geometry (cylindrical multiphase jet core surrounded by a coaxial annulus of gas) was established at the nozzle exit by introducing nitrogen gas into the annular gap between the jet nozzle two-phase effluent and the heated test section inlet. For the present study three basic post-CHF flow regimes have been observed: the rough wavy regime (inverted annular flow preliminary break down), the agitated regime (transition between inverted annular and dispersed droplet flow), and the dispersed ligament/droplet regime. For pre-CHF bubbly flow in the jet nozzle, the post-CHF flow (beginning from jet nozzle exit/heated test section inlet) consists of the rough wavy regime, followed by the agitated and then the dispersed ligament/droplet regime. In the same way, for pre-CHF slug flow in the jet core, the post-CHF flow is comprised of the agitated regime at the nozzle exit, followed by the dispersed regime. Pre-CHF annular jet core flow results in a small, depleted post-CHF agitated flow regime at the nozzle exit, immediately followed by the dispersed ligament/droplet regime. Observed post dryout hydrodynamic behavior is reported, with particular attention given to the transition flow pattern between inverted annular and dispersed droplet flow. 43 refs., 20 figs., 5 tabs

  1. Experimental study on an IC engine in-cylinder flow using different steady-state flow benches

    M. El-Adawy

    2017-12-01

    Full Text Available In-cylinder air flow structures are known to strongly impact on the performance and combustion of internal combustion engines (ICE. Therefore the aim of this paper is to experimentally study an IC engine in-cylinder flow under steady-state conditions. Different methods can be used to characterize the in-cylinder flow which are optical engines and laser diagnostics, computational fluid dynamic and steady-state flow bench. Here we are concentrating on two different types of flow benches. The first (Ricardo uses the impulse torque meter method while the other (FEV uses the paddle wheel technique. The experiments were carried out on the same cylinder head and the same pressure difference across the inlet valves of 600 mmH2O in order to compare the results. The experimental results are presented in terms of the measured air flow rate, flow coefficient, discharge coefficient and non-dimensional rig tumble. Moreover, number of modifications were conducted on the FEV flow bench in order to apply particle image velocimetry measurements on the vertical tumble plane, which passing through the middle of the cylinder at different valve lifts. The results show that a reasonably good level of agreement can be achieved between both methods, providing the methods of calculations of the various parameters are consistent. Keywords: In-cylinder flow, Flow bench, Tumble motion, Flow coefficient, Particle image velocimetry

  2. Laboratory study of orographic cloud-like flow

    Singh, Kanwar Nain; Sreenivas, K. R.

    2013-11-01

    Clouds are one of the major sources of uncertainty in climate prediction, listed in ``the most urgent scientific problems requiring attention'' IPCC. Also, convective clouds are of utmost importance to study the dynamics of tropical meteorology and therefore, play a key role in understanding monsoons. The present work is to study the dynamics of orographic clouds. Parameterization of these clouds will help in forecasting the precipitation accurately. Also, one could validate laboratory results from our study by actually measuring cloud development along a sloping terrain. In this context a planar buoyant turbulent wall jet is considered as an appropriate low order fluid-dynamical model for studying the turbulence and entrainment in orographic-clouds. Flow is volumetrically heated to mimic the latent heat release due to condensation in an actual cloud. This is the first step in studying the entrainment dynamics of the evolving orographic cloud. We are going to present some results on the cloud development using techniques that allows us to construct a 3-dimensional flow field at each instance and its development over the time. By combining velocity field from PIV and flow volume from PLIF at successive instances, we estimate the entrainment coefficient. Since the life-cycle of a cloud is determined by the entrainment of ambient air, these results could be extremely helpful in understanding the dynamics of the clouds. Detailed results will be presented at the conference.

  3. Preliminary study on the flow field over Greece

    Pissimanis, D; Karras, G; Notaridou, V; Bartzis, J.G.

    1989-02-01

    Full text: For radiation risk assessment from long distance sources, the knowledge of the synoptic air flow field patterns over the territory under consideration is required. In the present study a first representation of the air flow field in the atmospheric boundary layer over Greece is attempted. For this purpose, synoptic weather maps at 850mb available for a ten-years period, as well as sounding data from six meteorological stations were utilized, while the Greek territory was divided into four parts, i.e. NW, NE, SW, SE, with a number of stations in each sector. It was shown that the prevailing wind directions of the upper flow are either of the W/SW sector (winter, spring) or the northern sector (summer, autumn). In the SE sector a stronger tendency towards winds from the nothern sector was shown, due to the thermal low near Cyprus. The main characteristics of the surface flow is the strong influence by topographical features. Typical examples are the strong NW winds in Northern Greece due to the Vardar Valley, and the sea breeze circulations at coastal environments. (author)

  4. CFD Study of NACA 0018 Airfoil with Flow Control

    Eggert, Christopher A.; Rumsey, Christopher L.

    2017-01-01

    The abilities of two different Reynolds-Averaged Navier-Stokes codes to predict the effects of an active flow control device are evaluated. The flow control device consists of a blowing slot located on the upper surface of an NACA 0018 airfoil, near the leading edge. A second blowing slot present on the airfoil near mid-chord is not evaluated here. Experimental results from a wind tunnel test show that a slot blowing with high momentum coefficient will increase the lift of the airfoil (compared to no blowing) and delay flow separation. A slot with low momentum coefficient will decrease the lift and induce separation even at low angles of attack. Two codes, CFL3D and FUN3D, are used in two-dimensional computations along with several different turbulence models. Two of these produced reasonable results for this flow, when run fully turbulent. A more advanced transition model failed to predict reasonable results, but warrants further study using different inputs. Including inviscid upper and lower tunnel walls in the simulations was found to be important in obtaining pressure distributions and lift coefficients that best matched experimental data. A limited number of three-dimensional computations were also performed.

  5. 78 FR 52548 - The National Children's Study, Vanguard (Pilot) Study Proposed Collection; 60-day Comment Request

    2013-08-23

    ... longitudinal study of the interaction between environment, genetics on child health, and development. The Study defines ``environment'' broadly, taking a number of natural and man-made environmental, biological... Collection visits may include the administration of questionnaires, neurodevelopmental assessments, physical...

  6. Qualitative Data Collection and Interpretation: A Turkish Social Studies Lesson

    Tilman Grammes

    2016-05-01

    Full Text Available The classroom with its teaching-learning dynamics creates a kind of “embryonic society” in which the micro-policies of collective social knowledge construction and meaning can be re-constructed; therefore, it can be considered as a kind of “mirror” of political culture. Thus, comparative lesson research, which requires indepth classroom observation, has been getting much attention among educational community. On the other hand, there have not been done many studies that represent social studies and civics in particular, in this research tradition. Naturally, this research tradition is based on qualitative research paradigm. Likewise, qualitative research tradition has been getting increasing attention among educational community. Thus, the first purpose of this article is to explain all documentation and pre-interpretation process of this lesson so that it can provide an example for qualitative researchers. The second purpose of this article is to provide an example lesson of political education from Turkey so that educators worldwide can compare one example of social studies education practice in Turkey and with their countries.

  7. Valuation of medical resource units collected in health economic studies.

    Copley-Merriman, C; Lair, T J

    1994-01-01

    This paper reviews the issues that are critical for the valuation of medical resources in the context of health economic studies. There are several points to consider when undertaking the valuation of medical resources. The perspective of the analysis should be established before determining the valuation process. Future costs should be discounted to present values, and time and effort spent in assigning a monetary value to a medical resource should be proportional to its importance in the analysis. Prices vary considerably based on location of the service and the severity of the illness episode. Because of the wide variability in pricing data, sensitivity analysis is an important component of validation of study results. A variety of data sources have been applied to the valuation of medical resources. Several types of data are reviewed in this paper, including claims data, national survey data, administrative data, and marketing research data. Valuation of medical resources collected in clinical trials is complex because of the lack of standardization of the data sources. A national pricing data source for health economic valuation would greatly facilitate study analysis and make comparisons between results more meaningful.

  8. Numerical Studies of Homogenization under a Fast Cellular Flow

    Iyer, Gautam

    2012-09-13

    We consider a two dimensional particle diffusing in the presence of a fast cellular flow confined to a finite domain. If the flow amplitude A is held fixed and the number of cells L 2 →∞, then the problem homogenizes; this has been well studied. Also well studied is the limit when L is fixed and A→∞. In this case the solution averages along stream lines. The double limit as both the flow amplitude A→∞and the number of cells L 2 →∞was recently studied [G. Iyer et al., preprint, arXiv:1108.0074]; one observes a sharp transition between the homogenization and averaging regimes occurring at A = L 2. This paper numerically studies a few theoretically unresolved aspects of this problem when both A and L are large that were left open in [G. Iyer et al., preprint, arXiv:1108.0074] using the numerical method devised in [G. A. Pavliotis, A. M. Stewart, and K. C. Zygalakis, J. Comput. Phys., 228 (2009), pp. 1030-1055]. Our treatment of the numerical method uses recent developments in the theory of modified equations for numerical integrators of stochastic differential equations [K. C. Zygalakis, SIAM J. Sci. Comput., 33 (2001), pp. 102-130]. © 2012 Society for Industrial and Applied Mathematics.

  9. Numerical Studies of Homogenization under a Fast Cellular Flow

    Iyer, Gautam; Zygalakis, Konstantinos C.

    2012-01-01

    We consider a two dimensional particle diffusing in the presence of a fast cellular flow confined to a finite domain. If the flow amplitude A is held fixed and the number of cells L 2 →∞, then the problem homogenizes; this has been well studied. Also well studied is the limit when L is fixed and A→∞. In this case the solution averages along stream lines. The double limit as both the flow amplitude A→∞and the number of cells L 2 →∞was recently studied [G. Iyer et al., preprint, arXiv:1108.0074]; one observes a sharp transition between the homogenization and averaging regimes occurring at A = L 2. This paper numerically studies a few theoretically unresolved aspects of this problem when both A and L are large that were left open in [G. Iyer et al., preprint, arXiv:1108.0074] using the numerical method devised in [G. A. Pavliotis, A. M. Stewart, and K. C. Zygalakis, J. Comput. Phys., 228 (2009), pp. 1030-1055]. Our treatment of the numerical method uses recent developments in the theory of modified equations for numerical integrators of stochastic differential equations [K. C. Zygalakis, SIAM J. Sci. Comput., 33 (2001), pp. 102-130]. © 2012 Society for Industrial and Applied Mathematics.

  10. Experimental and numerical studies of two-phase microfluidic flows

    Mbanjwa, MB

    2010-09-01

    Full Text Available Flow of immiscible fluids is important in microfluidics for applications such as generation of emulsions and vesicles, drug delivery capsules, cell encapsulation and chemical reactions. The behaviour of these flows differs from large scale flows...

  11. Study on the flow state of groundwater by isotope tracer

    Lin Tong; Chen Jiansheng; Chen Liang

    2008-01-01

    Radioisotope logging technique is an effective method to evaluate groundwater movement. Moving with the water, the isotope tracer distributes differently in different flow states. According to the depth and time distribution of radioactivity, flow state of the groundwater can be determined. In this paper, different flow states, i.e. laminar flow, turbulent flow and mixing flow, are analyzed, and calculation of the flow velocity is discussed. Also, we discuss how to distinguish the laminar flow part and turbulent part in a mixing flow. If one judges the flow state incorrectly, the error of flow velocity will be huge, hence the importance of flow state analysis. Finally, some problems in the practical projects and measuring methods are concluded. (authors)

  12. Cold flow model study of an oxyfuel combustion pilot plant

    Guio-Perez, D.C.; Tondl, G.; Hoeltl, W.; Proell, T.; Hofbauer, H. [Vienna University of Technology, Institute of Chemical Engineering, Vienna (Austria)

    2011-12-15

    The fluid-dynamic behavior of a circulating fluidized bed pilot plant for oxyfuel combustion was studied in a cold flow model, down-scaled using Glicksman's criteria. Pressures along the unit and the global circulation rate were used for characterization. The analysis of five operating parameters and their influence on the system was carried out; namely, total solids inventory and the air velocity of primary, secondary, loop seal and support fluidizations. The cold flow model study shows that the reactor design allows stable operation at a wide range of fluidization rates, with results that agree well with previous observations described in the literature. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Physiologic Pressure and Flow Changes During Parabolic Flight (Pilot Study)

    Pantalos, George; Sharp, M. Keith; Mathias, John R.; Hargens, Alan R.; Watenpaugh, Donald E.; Buckey, Jay C.

    1999-01-01

    The objective of this study was to obtain measurement of cutaneous tissue perfusion central and peripheral venous pressure, and esophageal and abdominal pressure in human test subjects during parabolic flight. Hemodynamic data recorded during SLS-I and SLS-2 missions have resulted in the paradoxical finding of increased cardiac stroke volume in the presence of a decreased central venous pressure (CVP) following entry in weightlessness. The investigators have proposed that in the absence of gravity, acceleration-induced peripheral vascular compression is relieved, increasing peripheral vascular capacity and flow while reducing central and peripheral venous pressure, This pilot study seeks to measure blood pressure and flow in human test subjects during parabolic flight for different postures.

  14. Evaluation of municipal solid waste management performance by material flow analysis: Theoretical approach and case study.

    Zaccariello, Lucio; Cremiato, Raffaele; Mastellone, Maria Laura

    2015-10-01

    The main role of a waste management plan is to define which is the combination of waste management strategies and method needed to collect and manage the waste in such a way to ensure a given set of targets is reached. Objectives have to be sustainable and realistic, consistent with the environmental policies and regulations and monitored to verify the progressive achievement of the given targets. To get the aim, the setting up and quantification of indicators can allow the measurement of efficiency of a waste management system. The quantification of efficiency indicators requires the developing of a material flow analysis over the system boundary, from waste collection to secondary materials selling, processing and disposal. The material flow analysis has been carried out with reference to a case study for which a reliable, time- and site-specific database was available. The material flow analysis allowed the evaluation of the amount of materials sent to recycling, to landfilling and to waste-to-energy, by highlighting that the sorting of residual waste can further increase the secondary materials amount. The utilisation of energy recovery to treat the low-grade waste allows the maximisation of waste diversion from landfill with a low production of hazardous ash. A preliminary economic balance has been carried out to define the gate fee of the waste management system that was in the range of 84-145 € t(-1) without including the separate collection cost. The cost of door-by-door separate collection, designed to ensure the collection of five separate streams, resulted in 250 € t(-1) ±30%. © The Author(s) 2015.

  15. Study of ATES thermal behavior using a steady flow model

    Doughty, C.; Hellstroem, G.; Tsang, C. F.; Claesson, J.

    1981-01-01

    The thermal behavior of a single well aquifer thermal energy storage system in which buoyancy flow is neglected is studied. A dimensionless formulation of the energy transport equations for the aquifer system is presented, and the key dimensionless parameters are discussed. A simple numerical model is used to generate graphs showing the thermal behavior of the system as a function of these parameters. Some comparisons with field experiments are given to illustrate the use of the dimensionless groups and graphs.

  16. STUDY OF THE AIR FLOWS AROUND AN AIRPLANE

    Diaconescu Olivian

    2013-06-01

    Full Text Available This material presents a stage of the designing of an airplane capable to work with low capacity engines of 2.5 and 4 cmc namely the simulation of the air flow around the fuselage and the wings. The study proves the correctness of the choice made in the wing’s positioning and of the horizontal stabilizer of the airplane’s axis,for the chosen airplane type namely acrobat.

  17. STUDY OF THE AIR FLOWS AROUND AN AIRPLANE

    Diaconescu Olivian

    2013-01-01

    This material presents a stage of the designing of an airplane capable to work with low capacity engines of 2.5 and 4 cmc namely the simulation of the air flow around the fuselage and the wings. The study proves the correctness of the choice made in the wing’s positioning and of the horizontal stabilizer of the airplane’s axis,for the chosen airplane type namely acrobat.

  18. Contribution to the study of critical flow rates in a water-vapour two-phase flow

    Reocreux, Michel

    1974-01-01

    This research thesis aims at studying and analysing mechanisms involved in critical flows by adopting a theoretical and an experimental approach. After a recall of previous theoretical results and a discussion of their comparison with experimental results, the author outlines the main problems: the flow representation by a realistic model which takes all factors on which depend critical flow as well as many non critical flows into account, and the formulation of conditions to be met for a flow to be critical. Then, after a recall of the properties of critical single-phase flows, the author proposes an equation system. In the next part, he reports the development of an equation system for two-phase flows. The properties of the solutions of this system are studied to establish the general conditions required for a flow described by this system to be critical. These results are then applied to the equation system describing two-phase flows, and results are interpreted and discussed. In a second part, the author reports the experimental study by addressing experimental devices which could well produce the studied phenomenon, instrumentation and measurements, and the presentation and analysis of results [fr

  19. A Study on the Uncertainty of Flow-Induced Vibration in a Cross Flow over Staggered Tubes

    Kim, Ji-Su; Park, Jong-Woon [Dongguk univ, Gyeong Ju (Korea, Republic of); Choi, Hyeon-Kyeong [HanNam University, Daejeon (Korea, Republic of)

    2015-05-15

    Cross-flow in many support columns of very high temperature reactor (VHTR) lower plenum would have FIV issues under high speed flow jetting from the core. For a group of multiple circular cylinders subjected to a cross-flow, three types of potential vibration mechanisms may exist: (1) Vortex-induced vibration (VIV), (2) Fluid-elastic vibration (FEV) and (3) Turbulence-induced vibration (TIV). Kevalahan studied the free vibration of circular cylinders in a tightly packed periodic square inline array of cylinders. Pandey et al. studied the flue gas flow distribution in the Low Temperature Super Heater (LTSH) tube bundles situated in second pass of a utility boiler and the phenomenon of flow induced vibration. Nakamura et al. studied flow instability of cylinder arrays resembling U-bend tubes in steam generators. The FIV evaluation is usually performed with computational fluid dynamic (CFD) analysis to obtain unknown frequency of oscillation of the multiple objects under turbulent flow and thus the uncertainty residing in the turbulence model used should be quantified. In this paper, potential FIV uncertainty arising from the turbulence phenomena are evaluated for a typical cross flow through staggered tube bundles resembling the VHTR lower plenum support columns. Flow induced vibration (FIV) is one of the important mechanical and fatigue issues in nuclear systems. Especially, cross-flow in many support structures of VHTR lower plenum would have FIV issues under highly turbulent jet flows from the core. The results show that the effect of turbulence parameters on FIV is not negligible and the uncertainty is 5 to 10%. Present method can be applied to future FIV evaluations of nuclear systems. More extensive studies on flow induced vibration in a plant scale by using more rigorous computational methods are under way.

  20. Flow induced vibration studies on PFBR control plug components

    Prakash, V., E-mail: prakash@igcar.gov.in [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu (India); Kumar, P. Anup; Anandaraj, M.; Thirumalai, M.; Anandbabu, C.; Rajan, K.K. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu (India)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Flow induced vibration studies on Prototype Fast Breeder Reactor control plug model carried out. Black-Right-Pointing-Pointer Velocity similitude was followed for the study. Black-Right-Pointing-Pointer Frequencies and amplitude of vibrations of various control plug components measured. Black-Right-Pointing-Pointer Overall values of vibration are well within permissible limits. - Abstract: The construction of Prototype Fast Breeder Reactor (PFBR), a 500 MWe liquid sodium cooled reactor, is in progress at Kalpakkam in India. Control plug (CP) is located right above the core subassemblies in the hot pool. Control plug is an important component as many of the critical reactor parameters are sensed and controlled by the components housed in the control plug assembly. In PFBR primary circuit, components are basically thin walled, slender shells with diameter to thickness ratio ranging from 100 to 650. These components are prone to flow induced vibrations. The existence of free liquid (sodium) surfaces, which is the source of sloshing phenomenon and the operation of primary sodium pump in the primary pool are other potential sources of vibration of reactor components. Control plug is a hollow cylindrical shell structure and provides passages and support for 12 absorber rod drive mechanisms (ARDM) which consists of 9 control and safety rods and 3 diverse safety rods, 210 thermo wells to measure the sodium temperature at the exit of various fuel subassemblies, three failed fuel localization modules (FFLM) and acoustic detectors. It consists of a core cover plate (CCP), which forms the bottom end, two intermediate supports plate, i.e. lower stay plate (LSP) and upper stay plate (USP) and an outer shell. The CCP is located at a distance of 1.3 m from the core top. With such a gap, there will be long free hanging length of the thermocouple sleeves, Delayed neutron detector (DND) sampling tubes and ARDM shroud tubes and hence they are

  1. Leukocytospermia and sperm preparation - a flow cytometric study

    Perticarari Sandra

    2009-01-01

    Full Text Available Abstract Background Leukocytes represent the predominant source of reactive oxygen species both in seminal plasma and in sperm suspensions and have been demonstrated to negatively influence sperm function and fertilization rate in assisted reproduction procedures. Peroxidase test is the standard method recommended by WHO to detect semen leukocytes but it may be inaccurate. The aims of this study were (i to compare the efficiency of swim-up and density-gradient centrifugation techniques in removing seminal leukocytes, (ii to examine the effect of leukocytes on sperm preparation, and (iii to compare flow cytometry and peroxidase test in determining leukocyte concentration in semen using a multiparameter flow cytometric method. Methods Semen samples from 126 male partners of couples undergoing infertility investigations were analyzed for leukocytospermia using standard optical microscopy and flow cytometry. Sixty-nine out of 126 samples were also processed using simultaneously the swim-up and density-gradient centrifugation techniques. A multiparameter flow cytometric analysis to assess simultaneously sperm concentration, sperm viability, sperm apoptosis, and leukocyte concentration was carried out on neat and prepared sperm. Results Both sperm preparation methods removed most seminal leukocytes. However, the concentration of leukocytes was significantly lower after swim-up compared to that after density-gradient centrifugation preparation. Leukocytes concentration, either initial or in prepared fractions, was not correlated with sperm parameters (optical microscopy and flow cytometry parameters after semen processing. There was no correlation between leukocyte concentration in the ejaculate and sperm recovery rate, whereas a significant correlation was found between the concentration of the residual leukocytes in prepared fractions and viable sperm recovery rate. Although the overall concordance between the flow cytometry and the optical

  2. Limitations of radionuclide flow studies in bilateral carotid thrombosis

    Messert, B.; Tyson, I.B.; Barron, S.A.

    1975-01-01

    Radionuclide angiography as a noninvasive procedure has become an important tool in the evaluation of cerebrovascular diseases. Determinations of arm-to-brain circulation times complemented by the transit times of the radionuclide bolus through the brain afford insight into the functional status of the vascular system of the brain. Delays in perfusion, asymmetries in appearance, and washout of the radionuclide material can be correlated with disease entities. However, as with many procedures elevated to the status of a screening test, the possibility of false-positive and false-negative results exists. Two cases of bilateral carotid occlusion are presented, showing normal or only delayed, fairly symmetrical brain perfusion. The appearance of the radionuclide flow in the neck in AP and lateral views gave no suggestion of the involved deficits. Even multiple-projection imaging might fail to demonstrate major vascular obstructions. However, attentive study of these projections might yield interesting evidence of unexpected collateral flow systems. (U.S.)

  3. Experimental study on fundamental performance of reverse flow diverters

    Fan Yanfang; Xu Cong; Jing Shan

    2008-01-01

    The Reverse Flow Diverter (RFD) is one of the key components affecting the liquid-delivered efficiency. The effects of inflow structure, outflow structure, area ratio and suction gap on the performance of RFDs were studied in this paper. It can be found experimentally that expected entrainment phenomenon can be achieved when the outlet velocity of fluid for RFDs' inflow structure is sufficient. There is less liquid delivered by an RFD with a long receiver than that without a receiver. Because of back-flow caused by vortex separation, oversize area ratio cannot have better entrainment phenomenon and the optimum area ratio is 1.5. When the ratio of suction gap length to inlet diameter of outflow structure is 0.9-1.0, the excellent liquid-delivered efficiency can be obtained. (authors)

  4. Local Music Collections: Strategies for Digital Access, Presentation, and Preservation--A Case Study

    Doi, Carolyn

    2015-01-01

    The Saskatchewan Music Collection (SMC) is a local music collection held at the University of Saskatchewan. This case study examines a project to digitize and present this unique special collection in the online environment. The project aims to facilitate access to the collection, preserve the collection and promote scholarship and interest in the…

  5. Introduction to thematic collection "Historical and geological studies of earthquakes"

    Satake, Kenji; Wang, Jian; Hammerl, Christa; Malik, Javed N.

    2017-12-01

    This thematic collection contains eight papers mostly presented at the 2016 AOGS meeting in Beijing. Four papers describe historical earthquake studies in Europe, Japan, and China; one paper uses modern instrumental data to examine the effect of giant earthquakes on the seismicity rate; and three papers describe paleoseismological studies using tsunami deposit in Japan, marine terraces in Philippines, and active faults in Himalayas. Hammerl (Geosci Lett 4:7, 2017) introduced historical seismological studies in Austria, starting from methodology which is state of the art in most European countries, followed by a case study for an earthquake of July 17, 1670 in Tyrol. Albini and Rovida (Geosci Lett 3:30, 2016) examined 114 historical records for the earthquake on April 6, 1667 on the east coast of the Adriatic Sea, compiled 37 Macroseismic Data Points, and estimated the epicenter and the size of the earthquake. Matsu'ura (Geosci Lett 4:3, 2017) summarized historical earthquake studies in Japan which resulted in about 8700 Intensity Data Points, assigned epicenters for 214 earthquakes between AD 599 and 1872, and estimated focal depth and magnitudes for 134 events. Wang et al. (Geosci Lett 4:4, 2017) introduced historical seismology in China, where historical earthquake archives include about 15,000 sources, and parametric catalogs include about 1000 historical earthquakes between 2300 BC and AD 1911. Ishibe et al. (Geosci Lett 4:5, 2017) tested the Coulomb stress triggering hypothesis for three giant (M 9) earthquakes that occurred in recent years, and found that at least the 2004 Sumatra-Andaman and 2011 Tohoku earthquakes caused the seismicity rate change. Ishimura (2017) re-estimated the ages of 11 tsunami deposits in the last 4000 years along the Sanriku coast of northern Japan and found that the average recurrence interval of those tsunamis as 350-390 years. Ramos et al. (2017) studied 1000-year-old marine terraces on the west coast of Luzon Island, Philippines

  6. Study on performance and flow field of an undershot cross-flow water turbine comprising different number of blades

    Nishi, Yasuyuki; Hatano, Kentaro; Inagaki, Terumi

    2017-10-01

    Recently, small hydroelectric generators have gained attention as a further development in water turbine technology for ultra low head drops in open channels. The authors have evaluated the application of cross-flow water turbines in open channels as an undershot type after removing the casings and guide vanes to substantially simplify these water turbines. However, because undershot cross-flow water turbines are designed on the basis of cross-flow water turbine runners used in typical pipelines, it remains unclear whether the number of blades has an effect on the performance or flow fields. Thus, in this research, experiments and numerical analyses are employed to study the performance and flow fields of undershot cross-flow water turbines with varying number of blades. The findings show that the turbine output and torque are lower, the fluctuation is significantly higher, and the turbine efficiency is higher for runners with 8 blades as opposed to those with 24 blades.

  7. Studies of Two-Phase Gas-Liquid Flow in Microgravity. Ph.D. Thesis, Dec. 1994

    Bousman, William Scott

    1995-01-01

    Two-phase gas-liquid flows are expected to occur in many future space operations. Due to a lack of buoyancy in the microgravity environment, two-phase flows are known to behave differently than those in earth gravity. Despite these concerns, little research has been conducted on microgravity two-phase flow and the current understanding is poor. This dissertation describes an experimental and modeling study of the characteristics of two-phase flows in microgravity. An experiment was operated onboard NASA aircraft capable of producing short periods of microgravity. In addition to high speed photographs of the flows, electronic measurements of void fraction, liquid film thickness, bubble and wave velocity, pressure drop and wall shear stress were made for a wide range of liquid and gas flow rates. The effects of liquid viscosity, surface tension and tube diameter on the behavior of these flows were also assessed. From the data collected, maps showing the occurrence of various flow patterns as a function of gas and liquid flow rates were constructed. Earth gravity two-phase flow models were compared to the results of the microgravity experiments and in some cases modified. Models were developed to predict the transitions on the flow pattern maps. Three flow patterns, bubble, slug and annular flow, were observed in microgravity. These patterns were found to occur in distinct regions of the gas-liquid flow rate parameter space. The effect of liquid viscosity, surface tension and tube diameter on the location of the boundaries of these regions was small. Void fraction and Weber number transition criteria both produced reasonable transition models. Void fraction and bubble velocity for bubble and slug flows were found to be well described by the Drift-Flux model used to describe such flows in earth gravity. Pressure drop modeling by the homogeneous flow model was inconclusive for bubble and slug flows. Annular flows were found to be complex systems of ring-like waves and a

  8. Modern Special Collections Cataloguing: A University of London Case Study

    Attar, Karen

    2013-01-01

    Recent years have seen a growing emphasis on modern special collections (in themselves no new phenomenon), with a dichotomy between guidance for detailed cataloguing in Descriptive Cataloging of Rare Materials (Books) (DCRM(B), 2007) and the value of clearing cataloguing backlogs expeditiously. This article describes the De la Mare Family Archive of Walter de la Mare's Printed Oeuvre at Senate House Library, University of London, as an example of a modern author collections in an institutiona...

  9. Study on boiling heat transfer of subcooled flow under oscillatory flow condition

    Ohtake, Hiroyasu; Yamazaki, Satoshi; Koizumi, Yasuo

    2004-01-01

    The Onset of Nucleate Boiling, the point of Net Vapor Generation and Critical Heat Flux on subcooled flow boiling under oscillatory flow, focusing on liquid velocity, amplitude and frequency of oscillatory flow were investigated experimentally and analytically. Experiments were conducted using a copper thin-film and subcooled water in a range of the liquid velocity from 0.27 to 4.07 m/s at 0.10MPa. The liquid subcooling was 20K. Frequency of oscillatory flow was 2 and 4 Hz, respectively; amplitude of oscillatory flow was 25 and 50% in a ratio of main flow rate, respectively. Temperatures at Onset of Nuclear Boiling and Critical Heat Flux obtained in the experiments decreased with the oscillatory flow. The decrease of liquid velocity by oscillatory flow caused the ONB and the CHF to decrease. On the other hand, heat flux at Net Vapor Generation decreased with oscillatory flow; the increase of liquid velocity by oscillatory flow caused the NVG to decrease. (author)

  10. Museum theriological collections for the study of genetic diversity

    Ettore Randi

    2008-02-01

    Full Text Available Abstract Molecular methods to analyse DNA variability are opening new perspectives in the role played by museums in biodiversity research. DNA can be extracted from specific tissue collections, as well as from traditional voucher specimens. Ancient and museum DNA research produce valuable information for defining the phylogenetic positions of extinct taxa, the reconstruction of molecular and organismal evolution in extinct species, the characterization of extinct populations, including animal diets or microbial infections. Historical DNA samples are important sources of information also for conservation and evolutionary studies. In this paper, the methods used for ancient DNA analysis and the main results reported in published studies are reviewed. Riassunto Le collezioni teriologiche museali e lo studio della variabilità genetica. I metodi di analisi del DNA aprono nuove prospettive per il ruolo dei musei nello studio della biodiversità. Il DNA può essere estratto da collezioni di tessuti, oppure dai tradizionali materiali museali. Le ricerche che utilizzano DNA antico e museale possono produrre informazioni utili per definire la posizione filogenetica di taxa, la ricostruzione dell’evoluzione molecolare e fenotipica di specie e la caratterizzazione di popolazioni estinte, incluse l’identificazione della dieta e la presenza di malattie infettive. L’analisi del DNA estratto da campioni storici può fornire informazioni importanti anche per ricerche di biologia della conservazione. Si analizzano i metodi utilizzati per l’analisi del DNA antico, corredati da un breve excursus dei risultati delle principali ricerche disponibili in letteratura.

  11. Experimental study of turbulent flows through pipe bends

    Kalpakli, Athanasia

    2012-01-01

    This thesis deals with turbulent flows in 90 degree curved pipes of circular cross-section. The flow cases investigated experimentally are turbulent flow with and without an additional motion, swirling or pulsating, superposed on the primary flow. The aim is to investigate these complex flows in detail both in terms of statistical quantities as well as vortical structures that are apparent when curvature is present. Such a flow field can contain strong secondary flow in a plane normal to the ...

  12. Maternal attitudes toward DNA collection for gene-environment studies: a qualitative research study.

    Jenkins, Mary M; Reed-Gross, Erika; Rasmussen, Sonja A; Barfield, Wanda D; Prue, Christine E; Gallagher, Margaret L; Honein, Margaret A

    2009-11-01

    To assess attitudes toward DNA collection in an epidemiological study, focus groups were assembled in September 2007 with mothers who had participated in a case-control study of birth defects. Each recruited mother previously had completed an interview and had received a mailed kit containing cytobrushes to collect buccal cells for DNA from herself, her infant, and her infant's father during the period July 2004 through July 2007. A total of 38 mothers attended six focus groups comprising: (1) non-Hispanic Black mothers of case infants who participated or (2) did not participate in DNA collection, (3) mothers of any race or ethnicity who had case infants of low birth weight who participated or (4) did not participate in DNA collection, and (5) non-Hispanic Black mothers of control infants who participated or (6) did not participate in DNA collection. Moderator-led discussions probed maternal attitudes toward providing specimens, factors that influenced decision making, and collection method preferences. Biologics participants reported that they provided DNA for altruistic reasons. Biologics nonparticipants voiced concerns about government involvement and how their DNA will be used. Information provided (or not provided) on DNA use, storage, and disposal influenced decision making. Biologics participants and nonparticipants reported that paternal skepticism was a barrier to participation. All mothers were asked to rank DNA collection methods in terms of preference (cytobrushes, saliva, mouthwash, newborn blood spots, and blood collection). Preferred methods were convenient and noninvasive. Better understanding attitudes toward DNA collection and preferred collection methods might allow more inclusive participation and benefit future studies. Copyright 2009 Wiley-Liss, Inc.

  13. Effects of Nebulizer Position, Gas Flow, and CPAP on Aerosol Bronchodilator Delivery: An In Vitro Study.

    Ball, Lorenzo; Sutherasan, Yuda; Caratto, Valentina; Sanguineti, Elisa; Marsili, Maria; Raimondo, Pasquale; Ferretti, Maurizio; Kacmarek, Robert M; Pelosi, Paolo

    2016-03-01

    The aim of this study was to investigate the effects of different delivery circuit configurations, nebulizer positions, CPAP levels, and gas flow on the amount of aerosol bronchodilator delivered during simulated spontaneous breathing in an in vitro model. A pneumatic lung simulator was connected to 5 different circuits for aerosol delivery, 2 delivering CPAP through a high-flow generator tested at 30, 60, and 90 L/min supplementary flow and 5, 10, and 15 cm H2O CPAP and 3 with no CPAP: a T-piece configuration with one extremity closed with a cap, a T-piece configuration without cap and nebulizer positioned proximally, and a T-piece configuration without cap and nebulizer positioned distally. Albuterol was collected with a filter, and the percentage amount delivered was measured by infrared spectrophotometry. Configurations with continuous high-flow CPAP delivered higher percentage amounts of albuterol compared with the configurations without CPAP (9.1 ± 6.0% vs 6.2 ± 2.8%, P = .03). Among configurations without CPAP, the best performance was obtained with a T-piece with one extremity closed with a cap. In CPAP configurations, the highest delivery (13.8 ± 4.4%) was obtained with the nebulizer placed proximal to the lung simulator, independent of flow. CPAP at 15 cm H2O resulted in the highest albuterol delivery (P = .02). Based on our in vitro study, without CPAP, a T-piece with a cap at one extremity maximizes albuterol delivery. During high-flow CPAP, the nebulizer should always be placed proximal to the patient, after the T-piece, using the highest CPAP clinically indicated. Copyright © 2016 by Daedalus Enterprises.

  14. STUDY OF MERCURY OXIDATION BY SCR CATALYST IN AN ENTRAINED-FLOW REACTOR UNDER SIMULATED PRB CONDITIONS

    A bench-scale entrained-flow reactor system was constructed for studying elemental mercury oxidation under selective catalytic reduction (SCR) reaction conditions. Simulated flue gas was doped with fly ash collected from a subbituminous Powder River Basin (PRB) coal-fired boiler ...

  15. In vitro toxicological nanoparticle studies under flow exposure

    Sambale, Franziska, E-mail: sambale@iftc.uni-hannover.de; Stahl, Frank; Bahnemann, Detlef; Scheper, Thomas [Gottfried Wilhelm Leibniz University Hanover, Institute for Technical Chemistry (Germany)

    2015-07-15

    The use of nanoparticles is becoming increasingly common in industry and everyday objects. Thus, extensive risk management concerning the potential health risk of nanoparticles is important. Currently, in vitro nanoparticle testing is mainly performed under static culture conditions without any shear stress. However, shear stress is an important biomechanical parameter. Therefore, in this study, a defined physiological flow to different mammalian cell lines such as A549 cells and NIH-3T3 cells has been applied. The effects of zinc oxide and titanium dioxide nanoparticles (TiO{sub 2}-NP), respectively, were investigated under both static and dynamic conditions. Cell viability, cell morphology, and adhesion were proven and compared to the static cell culture. Flow exposure had an impact on the cellular morphology of the cells. NIH-3T3 cells were elongated in the direction of flow and A549 cells exhibited vesicles inside the cells. Zinc oxide nanoparticles reduced the cell viability in the static and in the dynamic culture; however, the dynamic cultures were more sensitive. In the static culture and in the dynamic culture, TiO{sub 2}-NP did not affect cell viability. In conclusion, dynamic culture conditions are important for further in vitro investigations and provide more relevant results than static culture conditions.

  16. In vitro toxicological nanoparticle studies under flow exposure

    Sambale, Franziska; Stahl, Frank; Bahnemann, Detlef; Scheper, Thomas

    2015-01-01

    The use of nanoparticles is becoming increasingly common in industry and everyday objects. Thus, extensive risk management concerning the potential health risk of nanoparticles is important. Currently, in vitro nanoparticle testing is mainly performed under static culture conditions without any shear stress. However, shear stress is an important biomechanical parameter. Therefore, in this study, a defined physiological flow to different mammalian cell lines such as A549 cells and NIH-3T3 cells has been applied. The effects of zinc oxide and titanium dioxide nanoparticles (TiO 2 -NP), respectively, were investigated under both static and dynamic conditions. Cell viability, cell morphology, and adhesion were proven and compared to the static cell culture. Flow exposure had an impact on the cellular morphology of the cells. NIH-3T3 cells were elongated in the direction of flow and A549 cells exhibited vesicles inside the cells. Zinc oxide nanoparticles reduced the cell viability in the static and in the dynamic culture; however, the dynamic cultures were more sensitive. In the static culture and in the dynamic culture, TiO 2 -NP did not affect cell viability. In conclusion, dynamic culture conditions are important for further in vitro investigations and provide more relevant results than static culture conditions

  17. Challenges in the flow measurement engineering study phases

    Henne, Liv Marit; Monnet, Jean

    2005-07-01

    Offshore development of marginal Oil and Gas fields can often be economically profitable if they can be tied in to existing platforms. This usually requires execution of comprehensive feasibility studies, which can often be a long and costly process. Close cooperation in a multi discipline engineering team is necessary to assure that all possibilities and aspects of the design task have been evaluated. Integration of a new flow measurement module on an existing installation is often the simplest solution, yielding low total cost as the module can be assembled and fully tested on shore. However on many installations one is required to integrate the new equipment in existing modules. Flow measurement is a crucial element in the development of marginal fields which has to be evaluated, taking into consideration all critical aspects such as: available space, weight, location accessibility, maintenance and integration to existing metering systems. In particular, special attention should be given to the possible use of new flow measurement technologies and principles. (author) (tk)

  18. Analytical study of solids-gas two phase flow

    Hosaka, Minoru

    1977-01-01

    Fundamental studies were made on the hydrodynamics of solids-gas two-phase suspension flow, in which very small solid particles are mixed in a gas flow to enhance the heat transfer characteristics of gas cooled high temperature reactors. Especially, the pressure drop due to friction and the density distribution of solid particles are theoretically analyzed. The friction pressure drop of two-phase flow was analyzed based on the analytical result of the single-phase friction pressure drop. The calculated values of solid/gas friction factor as a function of solid/gas mass loading are compared with experimental results. Comparisons are made for Various combinations of Reynolds number and particle size. As for the particle density distribution, some factors affecting the non-uniformity of distribution were considered. The minimum of energy dispersion was obtained with the variational principle. The suspension density of particles was obtained as a function of relative distance from wall and was compared with experimental results. It is concluded that the distribution is much affected by the particle size and that the smaller particles are apt to gather near the wall. (Aoki, K.)

  19. Study of streamline flow in the portal system

    Atkins, H.L.; Deitch, J.S.; Oster, Z.H.; Perkes, E.A.

    1985-01-01

    The study was undertaken to determine if streamline flow occurs in the portal vein, thus separating inflow from the superior mesenteric artery (SMA) and the inferior mesenteric artery. Previously published data on this subject is inconsistent. Patients undergoing abdominal angiography received two administrations of Tc-99m sulfur colloid, first via the SMA during angiography and, after completion of the angiographic procedure, via a peripheral vein (IV). Anterior images of the liver were recorded over a three minute acquisition before and after the IV injection without moving the patient. The image from the SMA injection was subtracted from the SMA and IV image to provide a pure IV image. Analysis of R to L ratios for selected regions of interest as well as whole lobes was carried out and the shift of R to L (SMA to IV) determined. Six patients had liver metastases from the colon, four had cirrhosis and four had no known liver disease. The shift in the ratio was highly variable without a consistent pattern. Large changes in some patients could be attributed to hepatic artery flow directed to metastases. No consistent evidence for streamlining of portal flow was discerned

  20. A Study on the Flow Characterization in the Reactor Cavity

    Lee, Ho Jung; Ko, Kwang Jeok; Kim, Sung Hwan; Kim, Min Gyu; Cho, Yeon Ho; Kim, Hyun Min [KEPCO Engineering and Construction Co. Ltd., Deajeon (Korea, Republic of)

    2016-10-15

    In this study, the flow characterization of the cooling air in reactor cavity nearby RCPSA has been analyzed by using a 3 dimensional model and the ANSYS CFX software in order to predict the Convective Heat Transfer Coefficient (CHTC) of the RCPSA. The Reactor Cavity is the annular space by the concrete structure, the Reactor Cavity Pool Seal Assembly (RCPSA), which consists of the welded steel and is designed to be installed between the RV and the refueling pool floor, and the Reactor Vessel (RV). For such reason, the RCPSA should be designed to provide the cooling air passage for ventilation to circulate high temperature air passing by the RV during the reactor operation. It means that the RCPSA is influenced by the convection of cooling air and the thermal expansion of the RV. Therefore, the flow characterization at the reactor cavity is one of the factors of the RCPSA design during the reactor operation. The flow distribution of the cooling air in reactor cavity nearby RCPSA has been analyzed using ANSYS CFX software to obtain the CHTC at surface of the RCPSA. 1) The temperature from the RV and the insulation is one of the critical factors for the thermal gradient of the cooling air and the CHTC in the reactor cavity. 2) The rapid change of the CHTC in inner region nearby inner and outer flexure is related to the geometry shape of the RCPSA and velocity of cooling air.

  1. A study of doppler waveform using pulsatile flow model

    Chung, Hye Won; Chung, Myung Jin; Park, Jae Hyung; Chung, Jin Wook; Lee, Dong Hyuk; Min, Byoung Goo

    1997-01-01

    Through the construction of a pulsatile flow model using an artificial heart pump and stenosis to demonstrate triphasic Doppler waveform, which simulates in vivo conditions, and to evaluate the relationship between Doppler waveform and vascular compliance. The flow model was constructed using a flowmeter, rubber tube, glass tube with stenosis, and artificial heart pump. Doppler study was carried out at the prestenotic, poststenotic, and distal segments;compliance was changed by changing the length of the rubber tube. With increasing proximal compliance, Doppler waveforms show decreasing peak velocity of the first phase and slightly delayed acceleration time, but the waveform itself did not change significantly. Distal compliance influenced the second phase, and was important for the formation of pulsus tardus and parvus, which without poststenotic vascular compliance, did not develop. The peak velocity of the first phase was inversely proportional to proximal compliance, and those of the second and third phases were directly proportional to distal compliance. After constructing this pulsatile flow model, we were able to explain the relationship between vascular compliance and Doppler waveform, and also better understand the formation of pulsus tardus and parvus

  2. Experimental study on flow past a rotationally oscillating cylinder

    Gao, Yang-yang; Yin, Chang-shan; Yang, Kang; Zhao, Xi-zeng; Tan, Soon Keat

    2017-08-01

    A series of experiments was carried out to study the flow behaviour behind a rotationally oscillating cylinder at a low Reynolds number (Re=300) placed in a recirculation water channel. A stepper motor was used to rotate the cylinder clockwise- and- counterclockwise about its longitudinal axis at selected frequencies. The particle image velocimetry (PIV) technique was used to capture the flow field behind a rotationally oscillating cylinder. Instantaneous and timeaveraged flow fields such as the vorticity contours, streamline topologies and velocity distributions were analyzed. The effects of four rotation angle and frequency ratios F r ( F r= f n/ f v, the ratio of the forcing frequency f n to the natural vortex shedding frequency f v) on the wake in the lee of a rotationally oscillating cylinder were also examined. The significant wake modification was observed when the cylinder undergoes clockwise-and-counterclockwise motion with amplitude of π, especially in the range of 0.6≤ F r≤1.0.

  3. Stability of phospholipid vesicles studied by asymmetrical flow field-flow fractionation and capillary electrophoresis

    Yohannes, Gebrenegus [Laboratory of Analytical Chemistry, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki (Finland); Pystynen, Kati-Henna [Laboratory of Analytical Chemistry, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki (Finland); Riekkola, Marja-Liisa [Laboratory of Analytical Chemistry, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki (Finland); Wiedmer, Susanne K. [Laboratory of Analytical Chemistry, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki (Finland)]. E-mail: susanne.wiedmer@helsinki.fi

    2006-02-23

    The stability of zwitterionic phosphatidylcholine vesicles in the presence of 20 mol% phosphatidyl serine (PS), phosphatidic acid (PA), phosphatidyl inositol (PI), and diacylphosphatidyl glycerol (PG) phospholipid vesicles, and cholesterol or calcium chloride was investigated by asymmetrical flow field-flow fractionation (AsFlFFF). Large unilamellar vesicles (LUV, diameter 100 nm) prepared by extrusion at 25 deg. C were used. Phospholipid vesicles (liposomes) were stored at +4 and -18 deg. C over an extended period of time. Extruded egg yolk phosphatidylcholine (EPC) particle diameters at peak maximum and mean measured by AsFlFFF were 101 {+-} 3 nm and 122 {+-} 5 nm, respectively. No significant change in diameter was observed after storage at +4 deg. C for about 5 months. When the storage period was extended to about 8 months (250 days) larger destabilized aggregates were formed (172 and 215 nm at peak maximum and mean diameters, respectively). When EPC was stored at -18 deg. C, large particles with diameters of 700-800 nm were formed as a result of dehydration, aggregation, and fusion processes. In the presence of calcium chloride, EPC alone did not form large aggregates. Addition of 20 mol% of negatively charged phospholipids (PS, PA, PI, or PG) to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) vesicles increased the electrostatic interactions between calcium ion and the vesicles and large aggregates were formed. In the presence of cholesterol, large aggregates of about 250-350 nm appeared during storage at +4 and -18 deg. C for more than 1 day. The effect of liposome storage temperature on phospholipid coatings applied in capillary electrophoresis (CE) was studied by measuring the electroosmotic flow (EOF). EPC coatings with and without cholesterol, PS, or calcium chloride, prepared from liposomes stored at +25, +4, and -18 deg. C, were studied at 25 deg. C. The performances of the coatings were further evaluated with three uncharged compounds

  4. Experimental study on unsteady open channel flow and bedload transport based on a physical model

    Cao, W.

    2015-12-01

    Flow in a nature river are usually unsteady, while nearly all the theories about bedload transport are on the basis of steady, uniform flow, and also with supposed equilibrium state of sediment transport. This is may be one of the main reasons why the bedload transport formulas are notoriously poor accuracy to predict the bedload. The aim of this research is to shed light on the effect of unsteadiness on the bedload transport based on experimental studies. The novel of this study is that the experiments were not carried out in a conventional flume but in a physical model, which are more similar to the actual river. On the other hand, in our experiments, multiple consecutive flood wave were reproduced in the physical model, and all the flow and sediment parameters are based on a large number of data obtained from many of identical flood waves. This method allow us to get more data for one flood, efficiently avoids the uncertainty of bedload rate only for one single flood wave, due to the stochastic fluctuation of the bedload transport. Three different flood waves were selected in the experiments. During each run of experiment, the water level of five different positions along the model were measured by ultrasonic water level gauge, flow velocity at the middle of the channel were measured by two dimensional electromagnetic current meter. Moreover, the bedload transport rate was measured by a unique automatic trap collecting and weighing system at the end of the physical model. The results shows that the celerity of flood wave propagate varies for different flow conditions. The velocity distribution was approximately accord with log-law profile during the entire rising and falling limb of flood. The bedload transport rate show intensity fluctuation in all the experiments, moreover, for different flood waves, the moment when the shear stress reaches its maximum value is not the exact moment when the sediment transport rate reaches its maximum value, which indicates

  5. Study of collective effects for the APIARY collider

    Zisman, M.S.

    1989-09-01

    The design of a high-luminosity electron-positron collider to study B-physics is a challenging task from many points of view. In this paper we consider the influence of collective effects on the machine performance; most of our findings are ''generic,'' in the sense that they depend rather weakly on the details of the machine design. Based upon an example machine design (APIARY-II), we investigate single-bunch thresholds for the longitudinal microwave and transverse mode-coupling instabilities, examine the possibility of emittance growth from intrabeam scattering, calculate the beam lifetime from Touschek scattering and gas scattering, and estimate the growth rates for both longitudinal and transverse coupled-bunch instabilities. We find that the single-bunch instabilities should not lead to difficulty, and that the emittance growth is essentially negligible. At a background gas pressure of 10 nTorr, beam lifetimes of only a few hours are expected, which will place a burden on the injection system if a high average luminosity is to be maintained. Even this lifetime is likely to require an innovative design for the vacuum system to maintain a pressure of 10 nTorr in the presence of a circulating electron or positron beam of approximately 1 A. With a standard PEP-like multicell rf system, multibunch growth rates are very severe, especially in the longitudinal plane. There appear to be significant benefits to a radically different rf system design, either utilizing superconducting single-cell rf cavities, or cavities with equivalent geometrical shapes but operated at room temperature. Even then, a powerful feedback system will likely be required. Nonetheless, it does not appear that there are any fundamental problems that stand in the way of successfully designing and building such a high-luminosity B-Factory. 13 refs., 9 figs., 5 tabs

  6. Asymmetrical flow field-flow fractionation with on-line detection for drug transfer studies: a feasibility study

    Hinna, A.; Steiniger, F.; Hupfeld, S.

    2014-01-01

    Knowledge about drug retention within colloidal carriers is of uppermost importance particularly if drug targeting is anticipated. The aim of the present study was to evaluate asymmetrical flow field-flow fractionation (AF4) with on-line UV/VIS drug quantification for its suitability to determine...... both release and transfer of drug from liposomal carriers to a model acceptor phase consisting of large liposomes. The hydrophobic porphyrin 5,10,15,20-tetrakis(4-hydroxyphenyl)21H,23H-porphine (p-THPP), a fluorescent dye with an absorbance maximum in the visible range and structural similarity...... channel geometries. Drug quantification by on-line absorbance measurements was established by comprehensive evaluation of the size-dependent turbidity contribution in on-line UV/VIS detection and by comparison with off-line results obtained for the respective dye-loaded donor formulations (dissolved...

  7. Damping parameter study of a perforated plate with bias flow

    Mazdeh, Alireza

    One of the main impediments to successful operation of combustion systems in industrial and aerospace applications including gas turbines, ramjets, rocket motors, afterburners (augmenters) and even large heaters/boilers is the dynamic instability also known as thermo-acoustic instability. Concerns with this ongoing problem have grown with the introduction of Lean Premixed Combustion (LPC) systems developed to address the environmental concerns associated with the conventional combustion systems. The most common way to mitigate thermo-acoustic instability is adding acoustic damping to the combustor using acoustic liners. Recently damping properties of bias flow initially introduced to liners only for cooling purposes have been recognized and proven to be an asset in enhancing the damping effectiveness of liners. Acoustic liners are currently being designed using empirical design rules followed by build-test-improve steps; basically by trial and error. There is growing concerns on the lack of reliability associated with the experimental evaluation of the acoustic liners with small size apertures. The development of physics-based tools in assisting the design of such liners has become of great interest to practitioners recently. This dissertation focuses primarily on how Large-Eddy Simulations (LES) or similar techniques such as Scaled Adaptive Simulation (SAS) can be used to characterize damping properties of bias flow. The dissertation also reviews assumptions made in the existing analytical, semi-empirical, and numerical models, provides a criteria to rank order the existing models, and identifies the best existing theoretical model. Flow field calculations by LES provide good insight into the mechanisms that led to acoustic damping. Comparison of simulation results with empirical and analytical studies shows that LES simulation is a viable alternative to the empirical and analytical methods and can accurately predict the damping behavior of liners. Currently the

  8. A study on light collection of small scintillating crystals

    Vittori, F; Malatesta, T; Puertolas, D

    2000-01-01

    Measurements are described concerning the light collection efficiency of YAP:Ce and CsI(Tl) crystals pillars with thicknesses ranging between 3 and 28 mm and cross-sections of 0.6 x 0.6 and 1 x 1 mm sup 2. These measurements have shown that the light collection is strongly dependent on the length of the pillar rather than on its cross-sectional area. A Monte Carlo code has been developed in order to evaluate the light collection efficiency as a function of the pillar geometry and surface treatment. Particular attention has been paid to the light transition through the crystal-photocathode window interface. The possibility to improve light detection by using a new photon detector provided with a YAP photocathode window has been verified.

  9. A study of critical two-phase flow models

    Siikonen, T.

    1982-01-01

    The existing computer codes use different boundary conditions in the calculation of critical two-phase flow. In the present study these boundary conditions are compared. It is shown that the boundary condition should be determined from the hydraulic model used in the computer code. The use of a correlation, which is not based on the hydraulic model used, leads often to bad results. Usually a good agreement with data is obtained in the calculation as far as the critical mass flux is concerned, but the agreement is not so good in the pressure profiles. The reason is suggested to be mainly in inadequate modeling of non-equilibrium effects. (orig.)

  10. Transverse flow reactor studies of the dynamics of radical reactions

    Macdonald, R.G. [Argonne National Laboratory, IL (United States)

    1993-12-01

    Radical reactions are in important in combustion chemistry; however, little state-specific information is available for these reactions. A new apparatus has been constructed to measure the dynamics of radical reactions. The unique feature of this apparatus is a transverse flow reactor in which an atom or radical of known concentration will be produced by pulsed laser photolysis of an appropriate precursor molecule. The time dependence of individual quantum states or products and/or reactants will be followed by rapid infrared laser absorption spectroscopy. The reaction H + O{sub 2} {yields} OH + O will be studied.

  11. Flow around a confined cylinder: LES and PIV study

    Palkin Egor

    2017-01-01

    Full Text Available We study the flow over a cylinder placed between two parallel rigid walls using Large-eddy simulations and Particle Image Velocimetry. The Reynolds number based on the inflow velocity and diameter of the cylinder is 3750 corresponding to the subcritical regime with laminar separation. Three-dimensional visualization shows the presence of the horseshoe vortex system prior to the cylinder. The comparison of time-averaged velocity fields and fluctuations shows good agreement between simulations and experiments. Spectral analysis suggests the presence of low-frequency modulations of the recirculating bubble.

  12. Using the developed cross-flow filtration chip for collecting blood plasma under high flow rate condition and applying the immunoglobulin E detection

    Yeh, Chia-Hsien; Hung, Chia-Wei; Wu, Chun-Han; Lin, Yu-Cheng

    2014-09-01

    This paper presents a cross-flow filtration chip for separating blood cells (white blood cells, red blood cells, and platelets) and obtaining blood plasma from human blood. Our strategy is to flow the sample solution in parallel to the membrane, which can generate a parallel shear stress to remove the clogging microparticles on the membrane, so the pure sample solution is obtained in the reservoir. The cross-flow filtration chip includes a cross-flow layer, a Ni-Pd alloy micro-porous membrane, and a reservoir layer. The three layers are packaged in a polymethylmethacrylate (PMMA) frame to create the cross-flow filtration chip. Various dilutions of the blood sample (original, 2 × , 3 × , 5 × , and 10×), pore sizes with different diameters (1 µm, 2 µm, 4 µm, 7 µm, and 10 µm), and different flow rates (1 mL/min, 3 mL/min, 5 mL/min, 7 mL/min, and 10 mL/min) are tested to determine their effects on filtration percentage. The best filtration percentage is 96.2% when the dilution of the blood sample is 10 × , the diameter of pore size of a Ni-Pd alloy micro-porous membrane is 2 µm, and the flow rate is 10 mL/min. Finally, for the clinical tests of the immunoglobulin E (IgE) concentration, the cross-flow filtration chip is used to filter the blood of the allergy patients to obtain the blood plasma. This filtered blood plasma is compared with that obtained using the conventional centrifugation based on the enzyme-linked immunosorbent assay. The results reveal that these two blood separation methods have similar detection trends. The proposed filtration chip has the advantages of low cost, short filtration time, and easy operation and thus can be applied to the separation of microparticles, cells, bacteria, and blood.

  13. Using the developed cross-flow filtration chip for collecting blood plasma under high flow rate condition and applying the immunoglobulin E detection

    Yeh, Chia-Hsien; Hung, Chia-Wei; Lin, Yu-Cheng; Wu, Chun-Han

    2014-01-01

    This paper presents a cross-flow filtration chip for separating blood cells (white blood cells, red blood cells, and platelets) and obtaining blood plasma from human blood. Our strategy is to flow the sample solution in parallel to the membrane, which can generate a parallel shear stress to remove the clogging microparticles on the membrane, so the pure sample solution is obtained in the reservoir. The cross-flow filtration chip includes a cross-flow layer, a Ni-Pd alloy micro-porous membrane, and a reservoir layer. The three layers are packaged in a polymethylmethacrylate (PMMA) frame to create the cross-flow filtration chip. Various dilutions of the blood sample (original, 2 × , 3 × , 5 × , and 10×), pore sizes with different diameters (1 µm, 2 µm, 4 µm, 7 µm, and 10 µm), and different flow rates (1 mL/min, 3 mL/min, 5 mL/min, 7 mL/min, and 10 mL/min) are tested to determine their effects on filtration percentage. The best filtration percentage is 96.2% when the dilution of the blood sample is 10 × , the diameter of pore size of a Ni-Pd alloy micro-porous membrane is 2 µm, and the flow rate is 10 mL/min. Finally, for the clinical tests of the immunoglobulin E (IgE) concentration, the cross-flow filtration chip is used to filter the blood of the allergy patients to obtain the blood plasma. This filtered blood plasma is compared with that obtained using the conventional centrifugation based on the enzyme-linked immunosorbent assay. The results reveal that these two blood separation methods have similar detection trends. The proposed filtration chip has the advantages of low cost, short filtration time, and easy operation and thus can be applied to the separation of microparticles, cells, bacteria, and blood. (paper)

  14. Evaluative study of collections and services of selected academic ...

    This paper evaluated the collections of Ramat Library, University of Maiduguri, Ibrahim Musa Library, Sir Kashim College of Education, and Ramat Polytechnic Library Maiduguri, in terms of availability of funds, currency, and quantity of the materials available for the benefit of all their users. Four objectives and four research ...

  15. Computational Study of Nonequilibrium Chemistry in High Temperature Flows

    Doraiswamy, Sriram

    Recent experimental measurements in the reflected shock tunnel CUBRC LENS-I facility raise questions about our ability to correctly model the recombination processes in high enthalpy flows. In the carbon dioxide flow, the computed shock standoff distance over the Mars Science Laboratory (MSL) shape was less than half of the experimental result. For the oxygen flows, both pressure and heat transfer data on the double cone geometry were not correctly predicted. The objective of this work is to investigate possible reasons for these discrepancies. This process involves systematically addressing different factors that could possibly explain the differences. These factors include vibrational modeling, role of electronic states and chemistry-vibrational coupling in high enthalpy flows. A state-specific vibrational model for CO2, CO, O2 and O system is devised by taking into account the first few vibrational states of each species. All vibrational states with energies at or below 1 eV are included in the present work. Of the three modes of vibration in CO2 , the antisymmetric mode is considered separately from the symmetric stretching mode and the doubly degenerate bending modes. The symmetric and the bending modes are grouped together since the energy transfer rates between the two modes are very large due to Fermi resonance. The symmetric and bending modes are assumed to be in equilibrium with the translational and rotational modes. The kinetic rates for the vibrational-translation energy exchange reactions, and the intermolecular and intramolecular vibrational-vibrational energy exchange reactions are based on experimental data to the maximum extent possible. Extrapolation methods are employed when necessary. This vibrational model is then coupled with an axisymmetric computational fluid dynamics code to study the expansion of CO2 in a nozzle. The potential role of low lying electronic states is also investigated. Carbon dioxide has a single excited state just below

  16. p-p minimum-bias dijets and nonjet quadrupole in relation to conjectured collectivity (flows in high-energy nuclear collisions

    Trainor Thomas A.

    2016-01-01

    Full Text Available Recent observations of ridge-like structure in p-p and p-A angular correlations at the RHIC and LHC have been interpreted to imply collective motion in smaller collision systems. It is argued that if correlation structures accepted as manifestations of flow in A-A collisions appear in smaller systems collectivity (flow must extend to the smaller systems. But the argument could be reversed to conclude that such structures appearing in A-A collisions may not imply hydrodynamic flow. I present spectrum, correlation and fluctuation data from RHIC p-p and Au-Au collisions and p-p, p-Pb and Pb-Pb results from the LHC described accurately by a two-component (soft+dijet model of hadron production. I also present evidence for a significant p-p nonjet (NJ quadrupole (v2 component with nch systematics directly related to A-A NJ quadrupole systematics. The combination suggests that soft, dijet and NJ quadrupole com- ponents are distinct phenomena in all cases, inconsistent with hadron production from a common bulk medium exhibiting collective motion (flow.

  17. Laser/fluorescent dye flow visualization technique developed for system component thermal hydraulic studies

    Oras, J.J.; Kasza, K.E.

    1988-01-01

    A novel laser flow visualization technique is presented together with examples of its use in visualizing complex flow patterns and plans for its further development. This technique has been successfully used to study (1) the flow in a horizontal pipe subject to temperature transients, to view the formation and breakup of thermally stratified flow and to determine instantaneous velocity distributions in the same flow at various axial locations; (2) the discharge of a stratified pipe flow into a plenum exhibiting a periodic vortex pattern; and (3) the thermal-buoyancy-induced flow channeling on the shell side of a heat exchanger with glass tubes and shell. This application of the technique to heat exchangers is unique. The flow patterns deep within a large tube bundle can be studied under steady or transient conditions. This laser flow visualization technique constitutes a very powerful tool for studying single or multiphase flows in complex thermal system components

  18. A numerical study of granular dam-break flow

    Pophet, N.; Rébillout, L.; Ozeren, Y.; Altinakar, M.

    2017-12-01

    Accurate prediction of granular flow behavior is essential to optimize mitigation measures for hazardous natural granular flows such as landslides, debris flows and tailings-dam break flows. So far, most successful models for these types of flows focus on either pure granular flows or flows of saturated grain-fluid mixtures by employing a constant friction model or more complex rheological models. These saturated models often produce non-physical result when they are applied to simulate flows of partially saturated mixtures. Therefore, more advanced models are needed. A numerical model was developed for granular flow employing a constant friction and μ(I) rheology (Jop et al., J. Fluid Mech. 2005) coupled with a groundwater flow model for seepage flow. The granular flow is simulated by solving a mixture model using Finite Volume Method (FVM). The Volume-of-Fluid (VOF) technique is used to capture the free surface motion. The constant friction and μ(I) rheological models are incorporated in the mixture model. The seepage flow is modeled by solving Richards equation. A framework is developed to couple these two solvers in OpenFOAM. The model was validated and tested by reproducing laboratory experiments of partially and fully channelized dam-break flows of dry and initially saturated granular material. To obtain appropriate parameters for rheological models, a series of simulations with different sets of rheological parameters is performed. The simulation results obtained from constant friction and μ(I) rheological models are compared with laboratory experiments for granular free surface interface, front position and velocity field during the flows. The numerical predictions indicate that the proposed model is promising in predicting dynamics of the flow and deposition process. The proposed model may provide more reliable insight than the previous assumed saturated mixture model, when saturated and partially saturated portions of granular mixture co-exist.

  19. Modeling study on the flow patterns of gas-liquid flow for fast decarburization during the RH process

    Li, Yi-hong; Bao, Yan-ping; Wang, Rui; Ma, Li-feng; Liu, Jian-sheng

    2018-02-01

    A water model and a high-speed video camera were utilized in the 300-t RH equipment to study the effect of steel flow patterns in a vacuum chamber on fast decarburization and a superior flow-pattern map was obtained during the practical RH process. There are three flow patterns with different bubbling characteristics and steel surface states in the vacuum chamber: boiling pattern (BP), transition pattern (TP), and wave pattern (WP). The effect of the liquid-steel level and the residence time of the steel in the chamber on flow patterns and decarburization reaction were investigated, respectively. The liquid-steel level significantly affected the flow-pattern transition from BP to WP, and the residence time and reaction area were crucial to evaluate the whole decarburization process rather than the circulation flow rate and mixing time. A superior flow-pattern map during the practical RH process showed that the steel flow pattern changed from BP to TP quickly, and then remained as TP until the end of decarburization.

  20. Modelling and Simulation of TCPAR for Power System Flow Studies

    Narimen Lahaçani AOUZELLAG

    2012-12-01

    Full Text Available In this paper, the modelling of Thyristor Controlled Phase Angle Regulator ‘TCPAR’ for power flow studies and the role of that modelling in the study of Flexible Alternating Current Transmission Systems ‘FACTS’ for power flow control are discussed. In order to investigate the impact of TCPAR on power systems effectively, it is essential to formulate a correct and appropriate model for it. The TCPAR, thus, makes it possible to increase or decrease the power forwarded in the line where it is inserted in a considerable way, which makes of it an ideal tool for this kind of use. Knowing that the TCPAR does not inject any active power, it offers a good solution with a less consumption. One of the adverse effects of the TCPAR is the voltage drop which it causes in the network although it is not significant. To solve this disadvantage, it is enough to introduce a Static VAR Compensator ‘SVC’ into the electrical network which will compensate the voltages fall and will bring them back to an acceptable level.

  1. A numerical study of two-phase Stokes flow in an axisymmetric flow-focusing device

    Jensen, Mads Jakob; Stone, H.A.; Bruus, Henrik

    2006-01-01

    We present a numerical investigation of the time-dependent dynamics of the creation of gas bubbles in an axisymmetric flow-focusing device. The liquid motion is treated as a Stokes flow, and using a generic framework we implement a second-order time-integration scheme and a free-surface model...... in MATLAB, which interfaces with the finite-element software FEMLAB. We derive scaling laws for the volume of a created bubble and for the gas flow rate, and confirm them numerically. Our results are consistent with existing experimental results by Garstecki et al. [Phys. Rev. Lett. 94, 164501 (2005...

  2. Study of Plasma Flow Modes in Imploding Nested Arrays

    Mitrofanov, K. N.; Aleksandrov, V. V.; Gritsuk, A. N.; Branitsky, A. V.; Frolov, I. N.; Grabovski, E. V.; Sasorov, P. V.; Ol'khovskaya, O. G.; Zaitsev, V. I.

    2018-02-01

    Results from experimental studies of implosion of nested wire and fiber arrays at currents of up to 4 MA at the Angara-5-1 facility are presented. Depending on the ratio between the radii of the inner and outer arrays, different modes of the plasma flow in the space between the inner and outer arrays were implemented: the sub-Alfvénic ( V r V A ) modes and a mode with the formation of the transition shock wave (SW) region between the cascades. By varying the material of the outer array (tungsten wires or kapron fibers), it is shown that the plasma flow mode between the inner and outer arrays depends on the ratio between the plasma production rates ṁ in / ṁ out in the inner and outer arrays. The obtained experimental results are compared with the results of one-dimensional MHD simulation of the plasma flow between the arrays. Stable implosion of the inner array plasma was observed in experiments with combined nested arrays consisting of a fiber outer array and a tungsten inner array. The growth rates of magnetic Rayleigh-Taylor (MRT) instability in the inner array plasma at different numbers of fibers in the outer array and different ratios between the radii of the inner and outer arrays are compared. Suppression of MRT instability during the implosion of the inner array plasma results in the formation of a stable compact Z-pinch and generation of a soft X-ray pulse. A possible scenario of interaction between the plasmas of the inner and outer arrays is offered. The stability of the inner array plasma in the stage of final compression depends on the character of interaction of plasma jets from the outer array with the magnetic field of the inner array.

  3. Studies of thermal-hydrodynamic flow instability, 2

    Suzuoki, Akira

    1977-01-01

    For reliable prediction of flow stability in sodium-heated steam generators, a dynamic model was proposed for boiling flow oscillation in parallel channel systems, and an analysis code was developed. The model contains a description of a sodium flow exchanging heat with a water flow in counter-current fashion. The code was applied to three representative flow systems whose heating conditions differed from each other, whereby their flow stabilities were compared with a focus on the effects of heating condition. Eigenvalues and flow impedances of the oscillation determined for each system reveal that: (1) Two fundamental systems for the steam generator, parallel tube system in an evaporator and steam generator modules arranged in parallel, have different stabilities under low frequency oscillation. (2) Existing analysis model conditioned on constant heat flux gives different results on stability from those of either steam generator model under low frequency oscillation. (auth.)

  4. Studies on turbulence structure and liquid film behavior in annular two-phase flow flowing in a throat section

    Yoshida, Kenji; Miyabe, Masaya; Matsumoto, Tadayoshi; Kataoka, Isao; Ohmori, Shuichi; Mori, Michitsugu

    2004-01-01

    Experimental studies on turbulence structure and liquid film behavior in annular two-phase flow were carried out concerned with the steam injector systems for a next-generation nuclear reactor. In the steam injector, steam/water annular two-phase flow is formed at the mixing nozzle. To make an appropriate design for high-performance steam injector system, it is very important to accumulate the fundamental data of thermo-hydro dynamic characteristics of annular flow in the steam injector. Especially, the turbulence modification in multi-phase flow due to the phase interaction is one of the most important phenomena and has attracted research attention. In this study, the liquid film behavior and the resultant turbulence modification due to the phase interaction were investigated. The behavior of the interfacial waves on liquid film flow such as the ripple or disturbance waves were observed to make clear the interfacial velocity and the special structure of the interfacial waves by using the high-speed video camera and the digital camera. The measurements for gas-phase velocity profiles and turbulent intensity in annular flow passing through the throat section were precisely performed to investigate quantitatively the turbulent modification in annular flow by using the constant temperature hot-wire anemometer. The measurements for liquid film thickness by the electrode needle method were also carried out. (author)

  5. Extended Macroscopic Study of Dilute Gas Flow within a Microcavity

    Mohamed Hssikou

    2016-01-01

    Full Text Available The behaviour of monatomic and dilute gas is studied in the slip and early transition regimes using the extended macroscopic theory. The gas is confined within a two-dimensional microcavity where the longitudinal sides are in the opposite motion with constant velocity ±Uw. The microcavity walls are kept at the uniform and reference temperature T0. Thus, the gas flow is transported only by the shear stress induced by the motion of upper and lower walls. From the macroscopic point of view, the regularized 13-moment equations of Grad, R13, are solved numerically. The macroscopic gas proprieties are studied for different values of the so-called Knudsen number (Kn, which gives the gas-rarefaction degree. The results are compared with those obtained using the classical continuum theory of Navier-Stokes and Fourier (NSF.

  6. Study of Spray Disintegration in Accelerating Flow Fields

    Nurick, W. H.

    1972-01-01

    An analytical and experimental investigation was conducted to perform "proof of principlem experiments to establish the effects of propellant combustion gas velocity on propella'nt atomization characteristics. The propellants were gaseous oxygen (GOX) and Shell Wax 270. The fuel was thus the same fluid used in earlier primary cold-flow atomization studies using the frozen wax method. Experiments were conducted over a range in L* (30 to 160 inches) at two contraction ratios (2 and 6). Characteristic exhaust velocity (c*) efficiencies varied from SO to 90 percent. The hot fire experimental performance characteristics at a contraction ratio of 6.0 in conjunction with analytical predictions from the drovlet heat-up version of the Distributed Energy Release (DER) combustion computer proDam showed that the apparent initial dropsize compared well with cold-flow predictions (if adjusted for the gas velocity effects). The results also compared very well with the trend in perfomnce as predicted with the model. significant propellant wall impingement at the contraction ratio of 2.0 precluded complete evaluation of the effect of gross changes in combustion gas velocity on spray dropsize.

  7. Radiometric Data Collection for Environmental Studies in Egypt

    Abdel Fattah, A.T.; Ramadan, A.A.; Gomaa, M.A.

    2001-01-01

    Radiation protection and monitoring in Egypt covers most fields of activities dealing with radioactivity. Such protection measures necessitate measurements of radiation levels, exposure or contamination whatever they are due to natural or man-made sources. A radiation level in foodstuff samples collected from selected main cities in Egypt was followed for several years after Chernobyl accident. Potassium-40 was found to be the main source of radioactivity. It ranges from 9 Bq/kg for macaroni to about 363 Bq/kg for watercress and broad beans. 137 Cs was found in trace amounts. Radiation measurements were carried out in soil samples collected from sixteen locations all over the country. The natural radiation level of 238 U, 232 Th and 40 K was found to be 7-27 Bq/kg, 3.8-24.4 Bq/kg and 105,7-448.9 Bq/kg respectively. This level was found to be higher in eastern parts of Egypt than in the western parts. Radiological control is precisely undertaken on the entry of food items and certain chemical materials used in industry. Contaminated food, higher than international trading levels, is rejected. Chemical materials containing radioactivity are followed during their uses. The annual effective dose from terrestrial gamma rays was determined for most Egyptian Governorates (106-371 UVv/y). Accordingly,the annual collective dose due to natural background radiation (terrestrial gamma rays and cosmic rays) is about 27,253 Man Sv. As a national need together with international attitude a monitoring network has been established few years after Chernobyl accident. It consists of 42 stations for gamma monitors in air,43 stations in water, 44 stations for beta aerosols, and 15 stations for conventional pollutants. The measured radiation levels are transmitted to control station via digital communication every 15 minutes

  8. Eye wash water flow direction study: an evaluation of the effectiveness of eye wash devices with opposite directional water flow

    Fogt JS; Jones-Jordan LA; Barr JT

    2018-01-01

    Jennifer S Fogt, Lisa A Jones-Jordan, Joseph T Barr The Ohio State University College of Optometry, Columbus, OH, USA Introduction: New designs of eye wash stations have been developed in which the direction of water flow from the fountain has been reversed, with two water streams originating nasally in both eyes and flowing toward the temporal side of each eye. No study has been done to determine the ideal direction of water flow coming from the eye wash in relation to the eye. Materials ...

  9. Technical investigation of cerebral blood flow measurements using the Patlak plot method. A contrivance for positioning of the gamma camera at data collection in radionuclide angiography

    Takaki, Akihiro; Okada, Kazuhiro; Urata, Johji; Yonehara, Toshiro [Saiseikai Kumamoto Hospital (Japan); Mizuta, Yoshihiko

    1999-02-01

    The time-activity curve for the aortic arch obtained from radionuclide angiography (RNA) is handled as an input function parameter according to the method of Matsuda et al., which determines regional cerebral blood flow non-invasively. The data are collected from a frontal view of the thorax captured by RNA by their method, however we encountered a case in which it was difficult to identify aortic arch in the data collection from the frontal view. The precise identification of the aortic arch was implemented when the RNA data were collected from the left anterior oblique view of the thorax. No significant difference was noted in the measured values between the data collection from the frontal view and from the left anterior oblique view. Our method seems to be useful modification of the Patlak plot method. (author)

  10. Using Temperature as a Tracer to Study Fluid Flow Patterns On and Offshore Taiwan

    Chi, W. C.

    2017-12-01

    Fluid flows are a dynamic system in the crust that affect crustal deformation and formation of natural resources. It is difficult to study fluid flow velocity instrumentally, but temperature data offers a quantitative tool that can be used as a tracer to study crustal hydrogeology. Here we present numerical techniques we have applied to study the fluid migration velocity along conduits including faults in on and offshore settings. Offshore SW Taiwan, we use a bottom-simulating reflector (BSR) from seismic profiles to study the temperature field at several hundred meters subbottom depth. The BSR is interpreted as the base of a gas hydrate stability zone under the seabed. Gas hydrates are solid-state water with gas molecules enclosed, which can be found where the temperature, pressure, and salinity conditions allow hydrates to be stable. Using phase diagrams and hydro pressure information we can derive the temperature at the BSR. BSRs are widespread in the study area, providing very dense temperature field information which shows upward bending of the BSR near faults. We have quantitatively estimated the 1D and 2D fluid flow patterns required to fit the BSR-based temperature field. This shows that fault zones can act as conduits with high permeability parallel to the fault planes. On the other hand, fault zones can also act as barriers to fluid flow, as demonstrated in our onland temperature data. We have collected temperature profiles at several bore holes onland that are very close together. The preliminary results show that the fault zones separate the ground water systems, causing very different geothermal gradients. Our results show that the physical properties of fault zones can be anisotropic, as demonstrated in previous work. Future work includes estimating the regional water expulsion budget offshore SW Taiwan, in particular for several gas hydrate sites.

  11. Experimental Studies of Low-Pressure Turbine Flows and Flow Control. Streamwise Pressure Profiles and Velocity Profiles

    Volino, Ralph

    2012-01-01

    This report summarizes research performed in support of the NASA Glenn Research Center (GRC) Low-Pressure Turbine (LPT) Flow Physics Program. The work was performed experimentally at the U.S. Naval Academy faculties. The geometry corresponded to "Pak B" LPT airfoil. The test section simulated LPT flow in a passage. Three experimental studies were performed: (a) Boundary layer measurements for ten baseline cases under high and low freestream turbulence conditions at five Reynolds numbers of 25,000, 50,000, 100,000, 200,000, and 300,000, based on passage exit velocity and suction surface wetted length; (b) Passive flow control studies with three thicknesses of two-dimensional bars, and two heights of three-dimensional circular cylinders with different spanwise separations, at same flow conditions as the 10 baseline cases; (c) Active flow control with oscillating synthetic (zero net mass flow) vortex generator jets, for one case with low freestream turbulence and a low Reynolds number of 25,000. The Passive flow control was successful at controlling the separation problem at low Reynolds numbers, with varying degrees of success from case to case and varying levels of impact at higher Reynolds numbers. The active flow control successfully eliminated the large separation problem for the low Reynolds number case. Very detailed data was acquired using hot-wire anemometry, including single and two velocity components, integral boundary layer quantities, turbulence statistics and spectra, turbulent shear stresses and their spectra, and intermittency, documenting transition, separation and reattachment. Models were constructed to correlate the results. The report includes a summary of the work performed and reprints of the publications describing the various studies.This report summarizes research performed in support of the NASA Glenn Research Center (GRC) Low-Pressure Turbine (LPT) Flow Physics Program. The work was performed experimentally at the U.S. Naval Academy

  12. A study on evaluation and analytical methods for groundwater flow with considering sea/fresh-water boundary. 1

    Anezaki, S.

    1998-03-01

    Sea/fresh-water boundary caused by density and concentration balance of sea-water and fresh-water is an important item for groundwater flow evaluation in deep underground near the coast. Also, in order to evaluate groundwater quality, it is important to understand the characteristics of sea/fresh-water boundary, for example boundary shape, salt distribution. In order to establish the evaluation and analytical methods for groundwater flow with considering sea/fresh-water boundary, we investigated the following items in this study. (1) Literature survey and data collection. (2) Investigation of analytical methods. (3) Planning of further study. (author). 78 refs

  13. PIV and CFD studies on analyzing intragastric flow phenomena induced by peristalsis using a human gastric flow simulator.

    Kozu, Hiroyuki; Kobayashi, Isao; Neves, Marcos A; Nakajima, Mitsutoshi; Uemura, Kunihiko; Sato, Seigo; Ichikawa, Sosaku

    2014-08-01

    This study quantitatively analyzed the flow phenomena in model gastric contents induced by peristalsis using a human gastric flow simulator (GFS). Major functions of the GFS include gastric peristalsis simulation by controlled deformation of rubber walls and direct observation of inner flow through parallel transparent windows. For liquid gastric contents (water and starch syrup solutions), retropulsive flow against the direction of peristalsis was observed using both particle image velocimetry (PIV) and computational fluid dynamics (CFD). The maximum flow velocity was obtained in the region occluded by peristalsis. The maximum value was 9 mm s(-1) when the standard value of peristalsis speed in healthy adults (UACW = 2.5 mm s(-1)) was applied. The intragastric flow-field was laminar with the maximum Reynolds number (Re = 125). The viscosity of liquid gastric contents hardly affected the maximum flow velocity in the applied range of this study (1 to 100 mPa s). These PIV results agreed well with the CFD results. The maximum shear rate in the liquid gastric contents was below 20 s(-1) at UACW = 2.5 mm s(-1). We also measured the flow-field in solid-liquid gastric contents containing model solid food particles (plastic beads). The direction of velocity vectors was influenced by the presence of the model solid food particle surface. The maximum flow velocity near the model solid food particles ranged from 8 to 10 mm s(-1) at UACW = 2.5 mm s(-1). The maximum shear rate around the model solid food particles was low, with a value of up to 20 s(-1).

  14. Sonographic evaluation of thyroiditis with color flow study.

    Sultana, N; Rima, S; Rahman, S; Azad, S A; Karim, M E; Shawkat, S; Ahsan, M; Kamal, M M; Begum, M

    2014-01-01

    This cross sectional study was carried out in the Department of Radiology and Imaging, Bangabandhu Sheikh Mujib Medical University, Bangladesh in collaboration with the Department of Endocrinology and Department of Histopathology of the same hospital during the period of March 2007 to February 2008 to determine efficacy of ultrasonogram in the evaluation of thyroiditis and to compare its results with color flow Doppler study. For this purpose, a total of 50 patients having clinical suspicion of thyroiditis were enrolled in this study. Ultrasound and color Doppler were done in all these patients. Then all patients underwent for FNAC in the Histopathology department. Correlation between sonographic diagnosis and histopathological diagnosis were observed. Out of these 50 patients 10(20%) were male and 40 (80%) were female with age ranging from 12 to 50 years, highest between 21 to 30 years. The mean age of the patients was 30.42±9.57 years. On unltrasonographic findings of thyroid gland 42.0% patients had regular and 58.0% had irregular margin. Seventy percent had fibrosis, 14.0% had feature of necrosis, 48.0% had lymphadenopathy. Out of all patients 6.0% had normal echogenic feature, 16.0% had increased and 78.0% decreased echogeneic feature. Twelve percent (12.0%) patients had homogeneous and 88.0% had heterogeneous pattern of echogenecity. Thirty eight percent (38%) patients had focal nodules. Sixty percent (60.0%) patients had focal swelling and 40.0% had diffuse swelling. On color flow Doppler 28.0% had normal, 38.0% had increased and 34.0% decreased vascular flow pattern. USG reports revealed that 48.0% had thyromegaly, 36.0% had thyroid nodule, 10.0% had multinodular goiter and 6.0% had thyroid abscess. FNAC diagnosis revealed that 34.0% patients had Hashimoto's thyroiditis, 24.0% had lymphocytic thyroiditis, 18.0% had granulomatous thyroiditis, 6.0% had abscess, 8.0% had goitre and 10.0% nonspecific. USG and CFD are recommended modalities for the diagnosis of

  15. Standardization of 8-color flow cytometry across different flow cytometer instruments: A feasibility study in clinical laboratories in Switzerland.

    Glier, Hana; Heijnen, Ingmar; Hauwel, Mathieu; Dirks, Jan; Quarroz, Stéphane; Lehmann, Thomas; Rovo, Alicia; Arn, Kornelius; Matthes, Thomas; Hogan, Cassandra; Keller, Peter; Dudkiewicz, Ewa; Stüssi, Georg; Fernandez, Paula

    2017-07-29

    The EuroFlow Consortium developed a fully standardized flow cytometric approach from instrument settings, through antibody panel, reagents and sample preparation protocols, to data acquisition and analysis. The Swiss Cytometry Society (SCS) promoted a study to evaluate the feasibility of using such standardized measurements of 8-color data across two different flow cytometry platforms - Becton Dickinson (BD) FACSCanto II and Beckman Coulter (BC) Navios, aiming at increasing reproducibility and inter-laboratory comparability of immunophenotypic data in clinical laboratories in Switzerland. The study was performed in two phases, i.e. a learning phase (round 1) and an analytical phase (rounds 2 and 3) consisting of a total of three rounds. Overall, 10 laboratories using BD FACSCanto II (n=6) or BC Navios (n=4) flow cytometers participated. Each laboratory measured peripheral blood samples from healthy donors stained with a uniform antibody panel of reagents - EuroFlow Lymphoid Screening Tube (LST) - applying the EuroFlow standardized protocols for instrument setup and sample preparation (www.EuroFlow.org). All data files were analyzed centrally and median fluorescence intensity (MedFI) values for individual markers on defined lymphocyte subsets were recorded; variability from reference MedFI values was assessed using performance scores. Data troubleshooting and discussion of the results with the participants followed after each round at SCS meetings. The results of the learning phase demonstrated that standardized instrument setup and data acquisition are feasible in routine clinical laboratories without previous experience with EuroFlow. During the analytical phase, highly comparable data were obtained at the different laboratories using either BD FACSCanto II or BC Navios. The coefficient of variation of MedFI for 7 of 11 markers performed repeatedly below 30%. In the last study round, 89% of participants scored over 90% MedFI values within the acceptance criteria

  16. Experimental Study on EHD Flow Transition in a Small Scale Wire-plate ESP

    Wang Chuan

    2016-06-01

    Full Text Available The electrohydrodynamic (EHD flow induced by the corona discharge was experimentally investigated in an electrostatic precipitator (ESP. The ESP was a narrow horizontal Plexiglas box (1300 mm×60 mm×60 mm. The electrode set consisted of a single wire discharge electrode and two collecting aluminum plate electrodes. Particle Image Velocimetry (PIV method was used to visualize the EHD flow characteristics inside the ESP seeded with fine oil droplets. The influence of applied voltage (from 8 kV to 10 kV and primary gas flow (0.15 m/s, 0.2 m/s, 0.4 m/s on the EHD flow transition was elucidated through experimental analysis. The formation and transition of typical EHD flows from onset to the fully developed were described and explained. Experimental results showed that the EHD flow patterns change depends on the gas velocity and applied voltage. EHD flow starts with flow streamlines near collecting plates bending towards the wire electrode, forming two void regions. An oscillating jet forming the downstream appeared and moved towards the wire electrode as voltage increased. For higher velocities (≥0.2 m/s, the EHD transition became near wire phenomenon with a jet-like flow structure near the wire, forming a void region behind the wire and expanding as voltage increased. Fully developed EHD secondary flow in the form of counter-rotating vortices appeared upstream with high applied voltage.

  17. Three-dimensional numerical study of flow and heat transfer from a cube placed in a uniform flow

    Saha, A.K.

    2006-01-01

    The fluid flow and heat transfer from a stationary cube placed in a uniform flow is studied numerically. The three-dimensional unsteady Navier Stokes and energy equations are solved using higher order temporal and spatial discretizations. Computations are carried out for a Reynolds number range of 50-400. At Re = 218, the symmetry seen at Re = 216 breaks down in one of the orthogonal planes while remains symmetric on the other thus showing a planar symmetry. The flow experiences a Hopf bifurcation at a Reynolds number between 265 and 270 and becomes unsteady. The thermal field also shows all the transitions same as those of flow transitions. The drag coefficient decreases while the heat transfer shows an increasing trend with Reynolds number. The transition from a steady to an unsteady flow does not show any significant increase in the heat transfer. Both the flow and thermal fields show multiple frequencies at high Reynolds number and the number of frequencies increases with the increase in Reynolds number. The instantaneous flow and temperature field are seen to deviate from planar symmetry at Re = 400

  18. Flow past an axially aligned spinning cylinder: Experimental Study

    Carlucci, Pasquale; Buckley, Liam; Mehmedagic, Igbal; Carlucci, Donald; Thangam, Siva

    2017-11-01

    Experimental investigation of flow past a spinning cylinder is presented in the context of its application and relevance to flow past projectiles. A subsonic wind tunnel is used to perform experiments on the flow past a spinning cylinder that is mounted on a forward sting and oriented such that its axis of rotation is aligned with the mean flow. The experiments cover a Reynolds number of range of up to 45000 and rotation numbers of up to 2 (based on cylinder diameter). Time-averaged mean flow and turbulence profiles in the wake flow are presented with and without spin along with comparison to published experimental data. Funded in part by the U. S. Army ARDEC, Picatinny Arsenal, NJ.

  19. Experimental study of natural circulation flow instability in rectangular channels

    Zhou, Tao; Qi, Shi; Song, Mingqiang [North China Electric Power Univ., Beijing (China). School of Nuclear Science and Engineering; Passive Nuclear Safety Technology, Beijing (China). Beijing Key Lab.; Xiao, Zejun [Nuclear, Reactor Thermal Hydraulics Technology, Chengdu (China). CNNC Key Lab.

    2017-05-15

    Experiments of natural circulation flow instability were conducted in rectangular channels with 5 mm and 10 mm wide gaps. Results for different heating powers were obtained. The results showed that the flow will tend to be instable with the growing of heating power. The oscillation period of pressure D-value and volume flow are the same, but their phase positions are opposite. They both can be described by trigonometric functions. The existence of edge position and secondary flow will strengthen the disturbance of fluid flow in rectangle channels, which contributes to heat transfer. The disturbance of bubble and fluid will be strengthened, especially in the saturated boiling section, which make it possible for the mixing flow. The results also showed that the resistance in 5 mm channel is bigger than that in 10 mm channel, it is less likely to form stable natural circulation in the subcooled region.

  20. Advances in studies of dense volcanic granular flows

    Bursik, M [University of Buffalo, SUNY, Buffalo, NY 14260 (United States); Patra, A [University of Buffalo, SUNY, Buffalo, NY 14260 (United States); Pitman, E B [University of Buffalo, SUNY, Buffalo, NY 14260 (United States); Nichita, C [University of Buffalo, SUNY, Buffalo, NY 14260 (United States); Macias, J L [Universidad Nacional Autonoma de Mexico, Coyoacan, Mexico D F (Mexico); Saucedo, R [Universidad Nacional Autonoma de Mexico, Coyoacan, Mexico D F (Mexico); Girina, O [Institute of Volcanic Geology and Geochemistry, Russian Academy of Sciences, Petropavlovsk-Kamchatskii (Russian Federation)

    2005-02-01

    The collapse and decrepitation of a lava dome at the summit of a volcano generally results in the generation of dense granular flows, often referred to as block and ash flows. As the dome particles propagate from the source, they break apart by internal pressure as well as collision. The propagation of block and ash flows can be simulated to some accuracy with a depth averaged numerical model of the equations of continuity and momentum for a material with a frictional resistance. However, important features of such flows, such as the influence of remote stress through force chains, erosion of the volcano substrate, and shock formation and pressurization upon particle break up are poorly understood. In the near future, the influence of these factors will be incorporated into depth averaged models. Various numerical techniques based on particles will some day yield results that can be compared not only with bulk flow properties, but to the internal layering of block and ash flow deposits.

  1. Radioactive tracer applications in the study of flow reactors. 4

    Thyn, J.; Hovorka, J.

    1975-01-01

    Response curves of gas streaming through the jet fluidized bed of a granular material in a rotary-jet pilot reactor were measured for a number of gas flow rates. A mathematical model of the gas residence time distribution was designed. Good agreement of the mathematical model with the experiments permits determining the ratio of streaming through the fluidized bed in form of bubbles of a different size. The measured values were evaluated as the distribution density of the gas residence time (age) at the outlet, the distribution function of the internal gas age in the device, and the so-called intensity function. The gas was labelled by a rapid injection of the radioactive 85 Kr and the response was studied by specially connected Geiger-Mueller counters placed inside the device, immediately above the granular material bed. (author)

  2. Experimental study of micro-shock tube flow

    Park, Jin Ouk; Kim, Gyu Wan; Rasel, Md. Alim Iftakhar [Dept. of Mechanical Engineering, Andong National University, Andong (Korea, Republic of); Kim, Heuy Dong [Fire Research Center, Korea Institute of Civil Engineering and Building Technology, Hwasung (Korea, Republic of)

    2015-03-15

    The flow characteristics in micro shock tube are investigated experimentally. Studies were carried out using a stainless steel micro shock tube. Shock and expansion wave was measured using 8 pressure sensors. The initial pressure ratio was varied from 4.3 to 30.5, and the diameter of tube was also changed from 3 mm to 6 mm. Diaphragm conditions were varied using two types of diaphragms. The results obtained show that the shock strength in the tube becomes stronger for an increase in the initial pressure ratio and diameter of tube. For the thinner diaphragm, the highest shock strength was found among varied diaphragm condition. Shock attenuation was highly influenced by the diameter of tube.

  3. Real-time data collection in Linux: a case study.

    Finney, S A

    2001-05-01

    Multiuser UNIX-like operating systems such as Linux are often considered unsuitable for real-time data collection because of the potential for indeterminate timing latencies resulting from preemptive scheduling. In this paper, Linux is shown to be fully adequate for precisely controlled programming with millisecond resolution or better. The Linux system calls that subserve such timing control are described and tested and then utilized in a MIDI-based program for tapping and music performance experiments. The timing of this program, including data input and output, is shown to be accurate at the millisecond level. This demonstrates that Linux, with proper programming, is suitable for real-time experiment software. In addition, the detailed description and test of both the operating system facilities and the application program itself may serve as a model for publicly documenting programming methods and software performance on other operating systems.

  4. A study on relationship between market share and cash flow policy

    Somayeh Sadeghi Moghaddam; Fateme Zabihi

    2014-01-01

    This paper presents an empirical investigation to study the relationship between cash flow and market share on selected firms from Tehran Stock Exchange over the period 2007-2011. Using regression analysis, the study has detected a positive and meaningful relationship between cash flow on one side and three other investment opportunities, firm size and operating cash flow. In addition, there is a negative and meaningful relationship between leverage and cash flow. However, the study does not ...

  5. Optimization of municipal waste collection scheduling and routing using vehicle assignment problem (case study of Surabaya city waste collection)

    Ramdhani, M. N.; Baihaqi, I.; Siswanto, N.

    2018-04-01

    Waste collection and disposal become a major problem for many metropolitan cities. Growing population, limited vehicles, and increased road traffic make the waste transportation become more complex. Waste collection involves some key considerations, such as vehicle assignment, vehicle routes, and vehicle scheduling. In the scheduling process, each vehicle has a scheduled departure that serve each route. Therefore, vehicle’s assignments should consider the time required to finish one assigment on that route. The objective of this study is to minimize the number of vehicles needed to serve all routes by developing a mathematical model which uses assignment problem approach. The first step is to generated possible routes from the existing routes, followed by vehicle assignments for those certain routes. The result of the model shows fewer vehicles required to perform waste collection asa well as the the number of journeys that the vehicle to collect the waste to the landfill. The comparison of existing conditions with the model result indicates that the latter’s has better condition than the existing condition because each vehicle with certain route has an equal workload, all the result’s model has the maximum of two journeys for each route.

  6. Experimental study of particle-driven secondary flow in turbulent pipe flows

    Belt, R.J.; Daalmans, A.C.L.M.; Portela, L.M.

    2012-01-01

    In fully developed single-phase turbulent flow in straight pipes, it is known that mean motions can occur in the plane of the pipe cross-section, when the cross-section is non-circular, or when the wall roughness is non-uniform around the circumference of a circular pipe. This phenomenon is known as secondary flow of the second kind and is associated with the anisotropy in the Reynolds stress tensor in the pipe cross-section. In this work, we show, using careful laser Doppler anemometry exper...

  7. Collective flow measurements with HADES in Au plus Au collisions at 1.23A GeV

    Kardan, B.; Chlad, Lukáš; Kugler, Andrej; Rodriguez Ramos, Pablo; Sobolev, Yuri, G.; Svoboda, Ondřej; Tlustý, Pavel; Wagner, Vladimír

    2017-01-01

    Roč. 967, č. 11 (2017), s. 812-815 ISSN 0375-9474. [26th International Conference on Ultrarelativistic Nucleus-Nucleus Collissions (Quark Matter). Chicago, 05.02.2017-11.02.2017] R&D Projects: GA ČR GA13-06759S; GA MŠk LM2015049; GA MŠk EF16_013/0001677 Institutional support: RVO:61389005 Keywords : heavy ion collisions * proton flow * directed flow Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nuclear physics Impact factor: 1.916, year: 2016

  8. Multidimensional analysis of collective sidewards flow in Au on Au reactions between 100 and 1050 A MeV

    Wienold, T.; Fan, Z.G.; Hartnack, C.

    1994-11-01

    An excitation function of the Au on Au reaction from 100 to 1050 A MeV was measured using the FOPI-facility at GSI Darmstadt. Nuclear charge (Z≤15) and velocity of the product were detected with full azimuthal acceptance at laboratory angles 1 ≤Θ lab ≤30 . For the first time an analysis is presented which combines the azimuthally asymmetric part of the transverse flow (sidewards flow), stopping and the associated collision geometry. In comparison to microscopic transport model calculations we demonstrate the relevance of this method for the extraction of the nuclear equation of state. (orig.)

  9. A study on the effect of gas flow rate on the wave characteristics in two-phase gas-liquid annular flow

    Han Huawei [Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, Oshawa, Ont., L1H 7K4 (Canada)]. E-mail: colin.han@uoit.ca; Zhu Zhenfeng [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, Sask., S7N 5A9 (Canada)]. E-mail: zhz752@mail.usask.ca; Gabriel, Kamiel [University of Ontario Institute of Technology, Oshawa, Ont., L1H 7K4 (Canada)]. E-mail: kamiel.gabriel@uoit.ca

    2006-12-15

    Interfacial waves play a very important role in the mass, momentum and energy transport phenomena in annular flow. In this paper, film thickness time-trace measurements for air-water annular flow were collected in a small vertical tube using a parallel wire probe. Using the data, a typical disturbance wave shape was obtained and wave properties (e.g., width, height, speed and roughness) were presented. The liquid mass flux ranged from 100 to 200 kg/m{sup 2} s and the gas mass flux ranged from 18 to 47 kg/m{sup 2} s. Disturbance wave characteristics were defined and the effects of changing the gas flow rate on the wave spacing, wave width, wave peak height and wave base height were studied. An average velocity model for the wave and base regions has been developed to determine the wave velocity. The investigation method could be further extended to annular-mist flow which frequently occurs in boiling water reactors.

  10. 76 FR 64368 - Notice of Submission of Proposed Information Collection to OMB Homelessness Prevention Study

    2011-10-18

    ... Proposed Information Collection to OMB Homelessness Prevention Study AGENCY: Office of Policy Development... Homelessness Prevention Study. The proposed information collection was approved under emergency review (OMB...) has submitted to OMB a request to extend approval for information collection for the Homelessness...

  11. Influence of slip velocity in Herschel-Bulkley fluid flow between parallel plates - A mathematical study

    Sankar, D. S.; Lee, U Sik

    2016-01-01

    This theoretical study investigates three types of basic flows of viscous incompressible Herschel-Bulkley fluid such as (i) plane Couette flow, (ii) Poiseuille flow and (iii) generalized Couette flow with slip velocity at the boundary. The analytic solutions to the nonlinear boundary value problems have been obtained. The effects of various physical parameters on the velocity, flow rate, wall shear stress and frictional resistance to flow are analyzed through appropriate graphs. It is observed that in plane Poiseuille flow and generalized Couette flow, the velocity and flow rate of the fluid increase considerably with the increase of the slip parameter, power law index, pressure gradient. The fluid velocity is significantly higher in plane Poiseuille flow than in plane Couette flow. The wall shear stress and frictional resistance to flow decrease considerably with the increase of the power law index and increase significantly with the increase of the yield stress of the fluid. The wall shear stress and frictional resistance to flow are considerably higher in plane Poiseuille flow than in generalized Couette flow.

  12. An experimental study on the effects of rectifiers on fluid flow

    Kawashima, G.

    1985-01-01

    This paper reports studies of various combinations of rectifiers and rectifying nets to measure fluid flow and in particular, the measurement of the flow through an orifice or nozzle, since they help to shorten the inlet length

  13. DNS Studies of Transitional Hypersonic Reacting Flows Over 3-D Hypersonic Vehicles

    Zhong, Xiaolin

    2003-01-01

    The objectives of this research project are to develop CFD techniques and to conduct DNS studies of fundamental flow physics leading to boundary-layer instability and transition in hypersonic flows...

  14. A video-image study of electrolytic flow structure in parallel electric-magnetic fields

    Gu, Z.H.; Fahidy, T.Z.

    1987-01-01

    The structure of free convective flow propagating from a vertical cathode into the electrolyte bulk has been studied via video-imaging. The enhancing effect of imposed horizontal uniform magnetic fields is manifest by vortex propagation and bifurcating flow

  15. Mitigation of Debris Flow Damage--­ A Case Study of Debris Flow Damage

    Lin, J. C.; Jen, C. H.

    Typhoon Toraji caused more than 30 casualties in Central Taiwan on the 31st July 2001. It was the biggest Typhoon since the Chi-Chi earthquake of 1999 with huge amounts of rainfall. Because of the influence of the earthquake, loose debris falls and flows became major hazards in Central Taiwan. Analysis of rainfall data and sites of slope failure show that damage from these natural hazards were enhanced as a result of the Chi-Chi earthquake. Three main types of hazard occurred in Central Taiwan: land- slides, debris flows and gully erosion. Landslides occurred mainly along hill slopes and banks of channels. Many dams and houses were destroyed by flooding. Debris flows occurred during typhoon periods and re-activated ancient debris depositions. Many new gullies were therefore developed from deposits loosened and shaken by the earthquake. This paper demonstrates the geological/geomorphological background of the hazard area, and reviews methods of damage mitigation in central Taiwan. A good example is Hsi-Tou, which had experienced no gully erosion for more than 40 years. The area experienced much gully erosion as a result of the combined effects of earth- quake and typhoon. Although Typhoon Toraji produced only 30% of the rainfall of Typhoon Herb of 1996, it caused more damage in the Hsi-Tou area. The mitigation of debris flow hazards in Hsi-tou area is discussed in this paper.

  16. Fourier analysis of cerebrospinal fluid flow velocities: MR imaging study. The Scandinavian Flow Group

    Thomsen, C; Ståhlberg, F; Stubgaard, M

    1990-01-01

    images. The phase information in the resultant image was converted to flow velocity with a calibration curve with the slope 26.5 radian.m-1.sec. The velocity versus time function was Fourier transformed and a continuous curve was fitted to the measured data with use of the first three harmonics...

  17. Experimental study of particle-driven secondary flow in turbulent pipe flows

    Belt, R.J.; Daalmans, A.C.L.M.; Portela, L.M.

    2012-01-01

    In fully developed single-phase turbulent flow in straight pipes, it is known that mean motions can occur in the plane of the pipe cross-section, when the cross-section is non-circular, or when the wall roughness is non-uniform around the circumference of a circular pipe. This phenomenon is known as

  18. Linking entropy flow with typhoon evolution: a case-study

    Liu, C; Xu, H; Liu, Y

    2007-01-01

    This paper is mainly aimed at investigating the relationship of entropy flow with an atmospheric system (typhoon), based on the observational analyses covering its whole life-cycle. The formula for calculating entropy flow is derived starting with the Gibbs relation with data from the NCEP/NCAR reanalysis. The results show that: (i) entropy flow characteristics at different vertical layers of the system are heterogeneous with predominant negative entropy flow in the large portion of the troposphere and positive ones at upper levels during its development; (ii) changes in the maximum surface wind velocity or the intensity of a typhoon are synchronous with the total entropy flow around the typhoon centre and its neighbourhood, suggesting that the growth of a severe atmospheric system relies greatly upon the negative entropy flow being strong enough, and that entropy flow analysis might provide a particular point of view and a powerful tool to understand the mechanism responsible for the life-cycle of an atmospheric system and associated weather events; and (iii) the horizontal pattern of negative entropy flow near the surface might contain some significant information conducive to the track forecast of typhoons

  19. Surfactant induced flows in thin liquid films : an experimental study

    Sinz, D.K.N.

    2012-01-01

    The topic of the experimental work summarized in my thesis is the flow in thin liquid films induced by non-uniformly distributed surfactants. The flow dynamics as a consequence of the deposition of a droplet of an insoluble surfactant onto a thin liquid film covering a solid substrate where

  20. Newton flows for elliptic functions: A pilot study

    Twilt, F.; Helminck, G.F.; Snuverink, M.; van den Brug, L.

    2008-01-01

    Elliptic Newton flows are generated by a continuous, desingularized Newton method for doubly periodic meromorphic functions on the complex plane. In the special case, where the functions underlying these elliptic Newton flows are of second-order, we introduce various, closely related, concepts of

  1. Theory, simulation, and experimental studies of zonal flows

    Hahm, T. S.; Burrell, K.H.; Lin, Z.; Nazikian, R.; Synakowski, E.J.

    2000-01-01

    The authors report on current theoretical understanding of the characteristics of self-generated zonal flows as observed in nonlinear gyrokinetic simulations of toroidal ITG turbulence [Science 281, 1835 (1998)], and discuss various possibilities for experimental measurements of signature of zonal flows

  2. Planning Student Flow with Linear Programming: A Tunisian Case Study.

    Bezeau, Lawrence

    A student flow model in linear programming format, designed to plan the movement of students into secondary and university programs in Tunisia, is described. The purpose of the plan is to determine a sufficient number of graduating students that would flow back into the system as teachers or move into the labor market to meet fixed manpower…

  3. Interpretation and value of MR CSF flow studies for paediatric ...

    Imaging techniques may be underutilised when clinicians are unaware of the technique or do not recognise its potential. Phase-contrast MR imaging (PC-MRI) is a rapid, simple and non-invasive technique that is sensitive to CSF flow. It demonstrates a mechanical coupling between cerebral blood and CSF flow throughout ...

  4. SPIV study of passive flow control on a WT airfoil

    Velte, Clara Marika; Hansen, Martin Otto Laver; Meyer, Knud Erik

    2010-01-01

    to free stream velocity U=15 m/s. The objective was to investigate the flow structures induced by and separation controlling behavior of vortex generators on the airfoil. The experimental results show strong separation of the uncontrolled flow whereas an intermittent behavior appears for the controlled...

  5. Exergy analysis of integrated photovoltaic thermal solar water heater under constant flow rate and constant collection temperature modes

    Tiwari, A.; Dubey, Swapnil; Sandhu, G.S.; Sodha, M.S.; Anwar, S.I.

    2009-01-01

    In this communication, an analytical expression for the water temperature of an integrated photovoltaic thermal solar (IPVTS) water heater under constant flow rate hot water withdrawal has been obtained. Analysis is based on basic energy balance for hybrid flat plate collector and storage tank,

  6. Analytical study of electron flows with a virtual cathode

    Dubinov, A.E.

    2000-01-01

    The dynamics of the electron flow behavior by its injection into a half-space is considered. Two problems are considered, namely the long-term injection of a monoenergetic electron flow and instantaneous flow injection with an assigned electron energy spectrum. The all flow electrons in both cases return to the injection plane. The simple analytical self-consistent model of the initial stage of the virtual cathode formation in a plane-parallel equipotential gap is plotted in the course of analysis whereof the duration of the virtual cathode formation process is determined. The performance of this model is not limited by the multivalence of the electron velocity in the flow. This makes it possible to extend the frames of the model performance relative to the moment of the virtual cathode formation and to consider its dynamics. The frequency of electron oscillations in the potential cathode-virtual cathode well is determined on the basis of the above model [ru

  7. Comment on 'Ion collection by a sphere in a flowing collisional plasma' [Phys. Plasmas 14, 034502 (2007)

    Hutchinson, I. H.

    2007-01-01

    It is shown that the numerical solutions presented in a recent paper discussing a highly simplified model of collisional particle collection are unnecessary because simple analytic solutions of the quantities presented are available

  8. Determination of salivary flow rate, pH, and dental caries during pregnancy: A study

    Amruta A Karnik

    2015-01-01

    Full Text Available Introduction: Saliva is an important diagnostic biofluid and the salivary composition is affected by various systemic conditions including pregnancy. Aims: The study was conducted to evaluate the salivary flow rate and pH in pregnant and non-pregnant Indian women and, consequently, to compare and correlate the salivary flow rate, pH, and prevalence of dental caries in both groups. Settings and Design: A cross-sectional study was conducted in our institute on a sample of 30 pregnant and 30 non-pregnant women. Materials and Methods: The clinical findings for Decayed-Missing-Filled Teeth (DMFT index were recorded. Unstimulated whole saliva was collected to determine the salivary flow rate and pH. Statistical Analysis Used: Data were statistically analyzed using Student′s t-test. Results: Salivary flow rate was lower in pregnant women (0.63 ml/min as compared to that in non-pregnant women (0.81 ml/min (P < 0.05 and the pH was also lesser in pregnant women (6.56 than in non-pregnant women (6.86 (P < 0.05. DMFT index showed a strong negative correlation with pH in pregnant women and non-pregnant women (P < 0.05. Conclusion: A difference was observed between the salivary parameters of pregnant and non-pregnant women in this sample. However, all the values were within the normal range. A significant inverse relation was found between salivary pH and dental caries for both the groups.

  9. Debris Flow Risk Management Framework and Risk Analysis in Taiwan, A Preliminary Study

    Tsao, Ting-Chi; Hsu, Wen-Ko; Chiou, Lin-Bin; Cheng, Chin-Tung; Lo, Wen-Chun; Chen, Chen-Yu; Lai, Cheng-Nong; Ju, Jiun-Ping

    2010-05-01

    Taiwan is located on a seismically active mountain belt between the Philippine Sea plate and Eurasian plate. After 1999's Chi-Chi earthquake (Mw=7.6), landslide and debris flow occurred frequently. In Aug. 2009, Typhoon Morakot struck Taiwan and numerous landslides and debris flow events, some with tremendous fatalities, were observed. With limited resources, authorities should establish a disaster management system to cope with slope disaster risks more effectively. Since 2006, Taiwan's authority in charge of debris flow management, the Soil and Water Conservation Bureau (SWCB), completed the basic investigation and data collection of 1,503 potential debris flow creeks around Taiwan. During 2008 and 2009, a debris flow quantitative risk analysis (QRA) framework, based on landslide risk management framework of Australia, was proposed and conducted on 106 creeks of the 30 villages with debris flow hazard history. Information and value of several types of elements at risk (bridge, road, building and crop) were gathered and integrated into a GIS layer, with the vulnerability model of each elements at risk applied. Through studying the historical hazard events of the 30 villages, numerical simulations of debris flow hazards with different magnitudes (5, 10, 25, 50, 100 and 200 years return period) were conducted, the economic losses and fatalities of each scenario were calculated for each creek. When taking annual exceeding probability into account, the annual total risk of each creek was calculated, and the results displayed on a debris flow risk map. The number of fatalities and frequency were calculated, and the F-N curves of 106 creeks were provided. For F-N curves, the individual risk to life per year of 1.0E-04 and slope of 1, which matched with international standards, were considered to be an acceptable risk. Applying the results of the 106 creeks onto the F-N curve, they were divided into 3 categories: Unacceptable, ALARP (As Low As Reasonable Practicable) and

  10. Independent Senior Women Who Travel Internationally: A Collective Case Study

    Jarrett, Barbara

    2010-01-01

    Nine independent women over age 55 who traveled internationally were investigated through a qualitative case study. The purpose of the study was to explore the women's attitudes, actions, and motivations during and after their international travel experiences. The adult, aging, experiential, and transformational theories of researchers such as…

  11. Discovering Jewish Studies Collections in Academic Libraries: A Practical Guide

    Taler, Izabella

    2014-01-01

    The U.S. colleges and universities offering non-sectarian educational programs in Jewish Studies rely on the support of their academic libraries for research materials and library services. For college libraries which use Library of Congress Classification scheme, it is a common practice to integrate "studies" resources into their…

  12. Numerical Studies of a Supersonic Fluidic Diverter Actuator for Flow Control

    Gokoglu, Suleyman A.; Kuczmarski, Maria A.; Culley, Dennis e.; Raghu, Surya

    2010-01-01

    The analysis of the internal flow structure and performance of a specific fluidic diverter actuator, previously studied by time-dependent numerical computations for subsonic flow, is extended to include operation with supersonic actuator exit velocities. The understanding will aid in the development of fluidic diverters with minimum pressure losses and advanced designs of flow control actuators. The self-induced oscillatory behavior of the flow is successfully predicted and the calculated oscillation frequencies with respect to flow rate have excellent agreement with our experimental measurements. The oscillation frequency increases with Mach number, but its dependence on flow rate changes from subsonic to transonic to supersonic regimes. The delay time for the initiation of oscillations depends on the flow rate and the acoustic speed in the gaseous medium for subsonic flow, but is unaffected by the flow rate for supersonic conditions

  13. Numerical Study of the Inertia Effect on Flow Distribution in Micro-gap Plate Heat Exchanger

    Park, Jang Min; Yoon, Seok Ho; Lee, Kong Hoon; Song Chan Ho

    2014-01-01

    This paper presents numerical study on flow and heat transfer characteristics in micro-gap plate heat exchanger. In particular, we investigate the effect of flow inertia on the flow distribution from single main channel to multiple parallel micro-gaps. The flow regime of the main channel is varied from laminar regime (Reynolds number of 100) to turbulent regime (Reynolds number of 10000) by changing the flow rate, and non-uniformity of the flow distribution and temperature field is evaluated quantitatively based on the standard deviation. The flow distribution is found to be significantly affected by not only the header design but also the flow rate of the main channel. It is also observed that the non-uniformity of the temperature field has its maximum at the intermediate flow regime

  14. Numerical Study of Flow Motion and Patterns Driven by a Rotating Permanent Helical Magnetic Field

    Yang, Wenzhi; Wang, Xiaodong; Wang, Bo; Baltaretu, Florin; Etay, Jacqueline; Fautrelle, Yves

    2016-10-01

    Liquid metal magnetohydrodynamic flow driven by a rotating permanent helical magnetic field in a cylindrical container is numerically studied. A three-dimensional numerical simulation provides insight into the visualization of the physical fields, including the magnetic field, the Lorentz force density, and the flow structures, especially the flow patterns in the meridional plane. Because the screen parameter is sufficiently small, the model is decoupled into electromagnetic and hydrodynamic components. Two flow patterns in the meridional plane, i.e., the global flow and the secondary flow, are discovered and the impact of several system parameters on their transition is investigated. Finally, a verifying model is used for comparison with the previous experiment.

  15. Studies on dispersive stabilization of porous media flows

    Daripa, Prabir, E-mail: prabir.daripa@math.tamu.edu; Gin, Craig [Department of Mathematics, Texas A& M University, College Station, Texas 77843 (United States)

    2016-08-15

    Motivated by a need to improve the performance of chemical enhanced oil recovery (EOR) processes, we investigate dispersive effects on the linear stability of three-layer porous media flow models of EOR for two different types of interfaces: permeable and impermeable interfaces. Results presented are relevant for the design of smarter interfaces in the available parameter space of capillary number, Peclet number, longitudinal and transverse dispersion, and the viscous profile of the middle layer. The stabilization capacity of each of these two interfaces is explored numerically and conditions for complete dispersive stabilization are identified for each of these two types of interfaces. Key results obtained are (i) three-layer porous media flows with permeable interfaces can be almost completely stabilized by diffusion if the optimal viscous profile is chosen, (ii) flows with impermeable interfaces can also be almost completely stabilized for short time, but become more unstable at later times because diffusion flattens out the basic viscous profile, (iii) diffusion stabilizes short waves more than long waves which leads to a “turning point” Peclet number at which short and long waves have the same growth rate, and (iv) mechanical dispersion further stabilizes flows with permeable interfaces but in some cases has a destabilizing effect for flows with impermeable interfaces, which is a surprising result. These results are then used to give a comparison of the two types of interfaces. It is found that for most values of the flow parameters, permeable interfaces suppress flow instability more than impermeable interfaces.

  16. Sustainable Consumer Behaviour: A Collection of Empirical Studies

    Gerrit Antonides

    2017-09-01

    Full Text Available We summarise the contributions in this special issue on sustainable consumer behaviour and place them in perspective. Several studies focus on macro- and meso-issues, and others on micro-issues of consumer behaviour. The studies employ a variety of methods, including surveys, field experiments, eye tracking, scale development, and contingent valuation. The 12 contributions from authors of 13 different countries show the wide and varied application of consumer research focused on sustainability issues.

  17. A national study of the streamflow data-collection program

    Benson, Manuel A.; Carter, Rolland William

    1973-01-01

    The streamflow data program of the U.S. Geological Survey was evaluated in a nationwide study during 1970. The principal elements of the study were (1) establishing the objectives and goals of the program, (2) analyzing all available data to determine which of the goals have already been met, (3) considering alternate means of meeting the remaining goals, and (4) identifying the elements which should be included in the future program.

  18. Sustainable Consumer Behaviour: A Collection of Empirical Studies

    Gerrit Antonides

    2017-01-01

    We summarise the contributions in this special issue on sustainable consumer behaviour and place them in perspective. Several studies focus on macro- and meso-issues, and others on micro-issues of consumer behaviour. The studies employ a variety of methods, including surveys, field experiments, eye tracking, scale development, and contingent valuation. The 12 contributions from authors of 13 different countries show the wide and varied application of consumer research focused on sustainabilit...

  19. Studies of Tracer Dispersion and Fluid Flow in Porous Media

    Rage, T.

    1996-12-31

    This doctoral thesis explores the connection between the topology of a porous medium and its macroscopic transport properties and is based on computerized simulation. In porous media, both diffusion and convection contribute to the dispersion of a tracer and their combined effect is emphasized. The governing equations are solved numerically, using finite differences and Monte Carlo technique. The influence of finite Reynolds number on the outcome of echo-experiments is discussed. Comparing experiments and simulations it is found that nonlinear inertial forces lead to a visible deformation of a returned tracer at surprisingly small Reynolds numbers. In a study of tracer dispersion and fluid flow in periodic arrays of discs it is demonstrated that the mechanisms of mechanical dispersion in periodic media and in natural (non-periodic) porous media are essentially different. Measurements of the percolation probability distribution of a sandstone sample is presented. Local porosity theory predicts that this simple geometric function of a porous medium is of dominant importance for its macroscopic transport properties. It is demonstrated that many aspects of transport through fractures can be studied by using simple but realistic models and readily available computer resources. An example may be the transport of hydrocarbon fluids from the source rock to a reservoir. 165 refs., 44 figs., 1 table

  20. Observation of Collective flow in interactions of 4.1(4.5) A GeV/c {sup 22}Ne({sup 28}Si) with Ag(Br)

    El-Naghy, A; Fakhraddin, S [Physics department, Faculty of Science, Cairo University, Giza (Egypt)

    2000-11-15

    The study of the transverse momentum analysis and the angle of flow analysis lead to the observation of the side ward flow of the nuclear matter in the interactions of 4.1(4.5) {sup 22}Ne({sup 28}Si) with Ag(Br). The distribution of the angle between the resultant vectors of the projectile and the target fragments showed a strong correlation between them in the azimuthal plane.

  1. Observation of Collective flow in interactions of 4.1(4.5) A GeV/c 22Ne(28Si) with Ag(Br)

    El-Naghy, A.; Fakhraddin, S.

    2000-01-01

    The study of the transverse momentum analysis and the angle of flow analysis lead to the observation of the side ward flow of the nuclear matter in the interactions of 4.1(4.5) 22 Ne( 28 Si) with Ag(Br). The distribution of the angle between the resultant vectors of the projectile and the target fragments showed a strong correlation between them in the azimuthal plane

  2. Study on flow regimes of high-pressure and dense-phase pneumatic conveying

    Lu Peng; Chen Xiaoping; Liang Cai; Pu Wenhao; Zhou Yun; Xu Pan; Zhao Changsui

    2009-01-01

    High-pressure and dense-phase pneumatic conveying of pulverized coal is a key technology in the field of large-scale entrained bed coal gasification. Flow regime plays an important role in two-phase flow because it affects not only flow behavior and safety operation, but also the reliability of practical processes. Few references and experiences in high-pressure and dense-phase conveying are available, especially for the flow regimes. And because of the high stickiness and electrostatic attraction of pulverized coal to the pipe wall, it is very difficult to make out the flow regimes in the conveying pipe by visualization method. Thus quartz powder was chosen as the conveyed material to study the flow regime. High-speed digital video camera was employed to photograph the flow patterns. Experiments were conducted on a pilot scale experimental setup at the pressure up to 3.6MPa. With the decrease in superficial gas velocity, three distinguishable flow regimes were observed: stratified flow, dune flow and plug flow. The characteristics of pressure traces acquired by high frequency response pressure transmitter and their EMD (Empirical Mode Decomposition) characteristics were correlated strongly with the flow regimes. Combining high-speed photography and pressure signal analysis together can make the recognition of flow patterns in the high-pressure and dense-phase pneumatic conveying system more accurate. The present work will lead to better understanding of the flow regime transition under high-pressure.

  3. A Neutron Scattering Study of Collective Excitations in Superfluid Helium

    Graf, E. H.; Minkiewicz, V. J.; Bjerrum Møller, Hans

    1974-01-01

    Extensive inelastic-neutron-scattering experiments have been performed on superfluid helium over a wide range of energy and momentum transfers. A high-resolution study has been made of the pressure dependence of the single-excitation scattering at the first maximum of the dispersion curve over...... of the multiexcitation scattering was also studied. It is shown that the multiphonon spectrum of a simple Debye solid with the phonon dispersion and single-excitation cross section of superfluid helium qualitatively reproduces these data....

  4. Theoretical study of inspiratory flow waveforms during mechanical ventilation on pulmonary blood flow and gas exchange.

    Niranjan, S C; Bidani, A; Ghorbel, F; Zwischenberger, J B; Clark, J W

    1999-08-01

    A lumped two-compartment mathematical model of respiratory mechanics incorporating gas exchange and pulmonary circulation is utilized to analyze the effects of square, descending and ascending inspiratory flow waveforms during mechanical ventilation. The effects on alveolar volume variation, alveolar pressure, airway pressure, gas exchange rate, and expired gas species concentration are evaluated. Advantages in ventilation employing a certain inspiratory flow profile are offset by corresponding reduction in perfusion rates, leading to marginal effects on net gas exchange rates. The descending profile provides better CO2 exchange, whereas the ascending profile is more advantageous for O2 exchange. Regional disparities in airway/lung properties create maldistribution of ventilation and a concomitant inequality in regional alveolar gas composition and gas exchange rates. When minute ventilation is maintained constant, for identical time constant disparities, inequalities in compliance yield pronounced effects on net gas exchange rates at low frequencies, whereas the adverse effects of inequalities in resistance are more pronounced at higher frequencies. Reduction in expiratory air flow (via increased airway resistance) reduces the magnitude of upstroke slope of capnogram and oxigram time courses without significantly affecting end-tidal expired gas compositions, whereas alterations in mechanical factors that result in increased gas exchanges rates yield increases in CO2 and decreases in O2 end-tidal composition values. The model provides a template for assessing the dynamics of cardiopulmonary interactions during mechanical ventilation by combining concurrent descriptions of ventilation, capillary perfusion, and gas exchange. Copyright 1999 Academic Press.

  5. Numerical and experimental studies of droplet-gas flow

    Joesang, Aage Ingebret

    2002-07-01

    This thesis considers droplet-gas flow by the use of numerical methods and experimental verification. A commercial vane separator was studied both numerical and by experiment. In addition some efforts are put into the numerical analysis of cyclones. The experimental part contains detailed measurements of the flow field between a pair of vanes in a vane separator and droplet size measurements. LDA (Laser Doppler Anemometry) was used to measure the velocity in two dimensions and corresponding turbulence quantities. The results from the LDA measurements are considered to be of high quality and are compared to numerical results obtained from a CFD (Computational Fluid Dynamics) analysis. The simulation showed good agreement between the numerical and experimental results. Combinations of different turbulence models; the standard k-epsilon model and the Reynold Stress Mode, different schemes; first order and higher order scheme and different near wall treatment of the turbulence; the Law of the wall and the Two-Layer Zonal model were used in the simulations. The Reynold Stress Model together with a higher order scheme performed rather poorly. The recirculation in parts of the separator was overpredicted in this case. For the other cases the overall predictions are satisfactory. PDA (Phase Doppler Anemometry) measurements were used to study the changes in the droplet size distribution through the vane separator. The PDA measurements show that smaller droplets are found at the outlet than present at the inlet. In the literature there exists different mechanisms for explaining the re-entrainment and generation of new droplets. The re-entrainments mechanisms are divided into four groups where droplet-droplet interaction, droplet break-up, splashing of impinging droplet and re-entrainment from the film are defined as the groups of re-entrainment mechanisms. Models for these groups are found in the literature and these models are tested for re-entrainment using the operational

  6. Implementation of the RAMMS DEBRIS FLOW to Italian case studies

    Vennari, Carmela; Mc Ardell, Brian; Parise, Mario; Santangelo, Nicoletta; Santo, Antonio

    2016-04-01

    RAMMS (RApid Mass MovementS) Debris Flow runout model solves 2D shallow-water equation using the Voellmy friction law. The model has been developed by the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), and the Swiss Federal Institute for Snow and Avalanche Research (SLF). It requires as input the following data: topography, release area or hydrograph, and the friction parameters μ and ξ. Deposition height, velocity, pressure and momentum are the most important outcomes, also in terms of Max values. The model was applied primarily in Alpine catchments to simulate debris flow runout. Beside the Alps, alluvial events are very common even in torrential catchments of the Southern Apennines of Italy, and contribute to build alluvial fans mainly located at the foothill of carbonate and volcanic mountains. During the last decades several events occurred in these areas, often highly populated, and caused serious damage to society and to people. Several case studies have been selected from a database on alluvial events in torrential catchments of Campania region, aimed at applying the RAMMS model to back-analyze the documented events, and to simulate future similar scenarios in different triggering conditions. In order to better understand the obtained data and choose the best results, field data are mandatories. For this reason we focused our attention on torrential events for which field data concerning deposition area and deposition height were available. We simulated different scenarios, with variable peak discharge and friction parameters, reproducing also the influence of anthropogenic structures. To choose the best results, observed data and predicted data were compared in an objective way, by means of a quantitative analysis. Predicted and observed deposition areas were compared in a GIS environment, and the best test was evaluated by computing several statistics accuracy derived from the confusion matrix, including the sensitivity, that

  7. Quantifying particulate matter deposition in Niwot Ridge, Colorado: Collection of dry deposition using marble inserts and particle imaging using the FlowCAM

    Goss, Natasha R.; Mladenov, Natalie; Seibold, Christine M.; Chowanski, Kurt; Seitz, Leslie; Wellemeyer, T. Barret; Williams, Mark W.

    2013-12-01

    Atmospheric wet and dry deposition are important sources of carbon for remote alpine lakes and soils. The carbon inputs from dry deposition in alpine National Atmospheric Deposition Program (NADP) collectors, including aeolian dust and biological material, are not well constrained due to difficulties in retaining particulate matter in the collectors. Here, we developed and tested a marble insert for dry deposition collection at the Niwot Ridge Long Term Ecological Research Station (NWT LTER) Soddie site (3345 m) between 24 May and 8 November 2011. We conducted laboratory tests of the insert's effect on particulate matter (PM) mass and non-purgeable organic carbon (DOC) and found that the insert did not significantly change either measurement. Thus, the insert may enable dry deposition collection of PM and DOC at NADP sites. We then developed a method for enumerating the collected wet and dry deposition with the Flow Cytometer and Microscope (FlowCAM), a dynamic-image particle analysis tool. The FlowCAM has the potential to establish morphology, which affects particle settling and retention, through particle diameter and aspect ratio. Particle images were used to track the abundance of pollen grains over time. Qualitative image examination revealed that most particles were biological in nature, such as intact algal cells and pollen. Dry deposition loading to the Soddie site as determined by FlowCAM measurements was highly variable, ranging from 100 to >230 g ha-1 d-1 in June-August 2011 and peaking in late June. No significant difference in diameter or aspect ratio was found between wet and dry deposition, suggesting fundamental similarities between those deposition types. Although FlowCAM statistics and identification of particle types proved insightful, our total-particle enumeration method had a high variance and underestimated the total number of particles when compared to imaging of relatively large volumes (60-125 mL) from a single sample. We recommend use of

  8. 78 FR 20796 - Data Specifications for Collecting Study Area Boundaries

    2013-04-08

    ..., DC 20554, and may also be purchased from the Commission's copy contractor, BCPI, Inc., Portals II... submission. Third, the Bureau permits incumbent LECs that are price cap carriers to submit exchange-level... study area boundary data should notify the Commission in writing of their intention to do so by filing a...

  9. Rural Action: A Collection of Community Work Case Studies.

    Henderson, Paul, Ed.; Francis, David, Ed.

    This book contains 10 case studies of rural community development in England, Wales, Scotland, Ireland, and Catalonia, as seen from the perspective of community-work practitioners. Development projects encompassed such activities as promotion of tourism, establishment of community centers, vocational training for school dropouts, adult community…

  10. Comparative study on flow rate measurement by nuclear and conventional methods in selected rivers at Ulu Langat district, Selangor

    Wan Mohamad Tahir, Wan Zakaria; Mohamad, Daud; Hamzah, Abdul Razak; Yusuf, Johari Mohamad; Aziz Wan Mohamad, Wan Abdul

    1986-06-01

    A radiotracer technique using Tc-99 to measure flows of small rivers was introduced in Malaysia. Three rivers in the Ulu Langat District were selected for a comparative study on flow rate determination by conventional and radioisotope methods. Radioisotopic approach, comprising injection procedures, calibration, mixing length and safety aspects are discussed. The results measured by radioisotope method are compared to the Drainage and Irrigation Department's (DID's) discharge curves data collected from 1980 to 1982 which is calibrated using a current meter. The results are comparable and fall within the range obtained by conventional method. Related to this study, a comprehensive work on stream gauging of moderate and high flow rates using both methods is proposed to be carried out directly.

  11. Study on flow instabilities in two-phase mixtures

    Ishii, M.

    1976-03-01

    Various mechanisms that can induce flow instabilities in two-phase flow systems are reviewed and their relative importance discussed. In view of their practical importance, the density-wave instabilities have been analyzed in detail based on the one-dimensional two-phase flow formulation. The dynamic response of the system to the inlet flow perturbations has been derived from the model; thus the characteristic equation that predicts the onset of instabilities has been obtained. The effects of various system parameters, such as the heat flux, subcooling, pressure, inlet velocity, inlet orificing, and exit orificing on the stability boundary have been analyzed. In addition to numerical solutions, some simple stability criteria under particular conditions have been obtained. Both results have been compared with various experimental data, and a satisfactory agreement has been demonstrated

  12. Flow Regime Classification and Hydrological Characterization: A Case Study of Ethiopian Rivers

    Belete Berhanu

    2015-06-01

    Full Text Available The spatiotemporal variability of a stream flow due to the complex interaction of catchment attributes and rainfall induce complexity in hydrology. Researchers have been trying to address this complexity with a number of approaches; river flow regime is one of them. The flow regime can be quantified by means of hydrological indices characterizing five components: magnitude, frequency, duration, timing, and rate of change of flow. Similarly, this study aimed to understand the flow variability of Ethiopian Rivers using the observed daily flow data from 208 gauging stations in the country. With this process, the Hierarchical Ward Clustering method was implemented to group the streams into three flow regimes (1 ephemeral, (2 intermittent, and (3 perennial. Principal component analysis (PCA is also applied as the second multivariate analysis tool to identify dominant hydrological indices that cause the variability in the streams. The mean flow per unit catchment area (QmAR and Base flow index (BFI show an incremental trend with ephemeral, intermittent and perennial streams. Whereas the number of mean zero flow days ratio (ZFI and coefficient of variation (CV show a decreasing trend with ephemeral to perennial flow regimes. Finally, the streams in the three flow regimes were characterized with the mean and standard deviation of the hydrological variables and the shape, slope, and scale of the flow duration curve. Results of this study are the basis for further understanding of the ecohydrological processes of the river basins in Ethiopia.

  13. An Experimental study on a Method of Computing Minimum flow rate

    Cho, Yeon Sik; Kim, Tae Hyun; Kim, Chang Hyun

    2009-01-01

    Many pump reliability problems in the Nuclear Power Plants (NPPs) are being attributed to the operation of the pump at flow rates well below its best efficiency point(BEP). Generally, the manufacturer and the user try to avert such problems by specifying a minimum flow, below which the pump should not be operated. Pump minimum flow usually involves two considerations. The first consideration is normally termed the 'thermal minimum flow', which is that flow required to prevent the fluid inside the pump from reaching saturation conditions. The other consideration is often referred to as 'mechanical minimum flow', which is that flow required to prevent mechanical damage. However, the criteria for specifying such a minimum flow are not clearly understood by all parties concerned. Also various factor and information for computing minimum flow are not easily available as considering for the pump manufacturer' proprietary. The objective of this study is to obtain experimental data for computing minimum flow rate and to understand the pump performances due to low flow operation. A test loop consisted of the pump to be used in NPPs, water tank, flow rate measurements and piping system with flow control devices was established for this study

  14. Feasibility of flow studies at NICA/MPD

    Geraksiev, N. S., E-mail: nikolay.geraksiev@gmail.com [Plovdiv University “Paisii Hilendarski”, FPET (Bulgaria); Collaboration: MPD Collaboration

    2015-12-15

    In the light of recent developments in heavy ion physic, anisotropic flow measurements play a key role in a better understanding of the hot and dense barionic matter. In the presented article a short introduction to the proposed NICA/MPD project is given, as well as a brief description of the event-plane method used to estimate the elliptic flow of reconstructed and identified hadrons (p, π, Λ)

  15. Studying and modelling variable density turbulent flows for industrial applications

    Chabard, J.P.; Simonin, O.; Caruso, A.; Delalondre, C.; Dalsecco, S.; Mechitoua, N.

    1996-07-01

    Industrial applications are presented in the various fields of interest for EDF. A first example deals with transferred electric arcs couplings flow and thermal transfer in the arc and in the bath of metal and is related with applications of electricity. The second one is the combustion modelling in burners of fossil power plants. The last one comes from the nuclear power plants and concerns the stratified flows in a nuclear reactor building. (K.A.). 18 refs.

  16. Studying and modelling variable density turbulent flows for industrial applications

    Chabard, J.P.; Simonin, O.; Caruso, A.; Delalondre, C.; Dalsecco, S.; Mechitoua, N.

    1996-07-01

    Industrial applications are presented in the various fields of interest for EDF. A first example deals with transferred electric arcs couplings flow and thermal transfer in the arc and in the bath of metal and is related with applications of electricity. The second one is the combustion modelling in burners of fossil power plants. The last one comes from the nuclear power plants and concerns the stratified flows in a nuclear reactor building. (K.A.)

  17. Field studies of transport and dispersion of atmospheric tracers in nocturnal drainage flows

    Paul H. Gudiksen; Gilbert J. Ferber; Malcolm M. Fowler; Wynn L. Eberhard; Michael A. Fosberg; William R. Knuth

    1984-01-01

    A series of tracer experiments were carried out as part of the Atmospheric Studies in Complex Terrain (ASCOT) program to evaluate pollutant transport and dispersion characteristics of nocturnal drainage flows within a valley in northern California. The results indicate that the degree of interaction of the drainage flows with the larger scale regional flows are...

  18. Experimental Study of Annulus Flow for Can Combustor with Vibration Influence

    Rami. Y. Dahham

    2018-01-01

    Full Text Available This paper concentrate on studying the behavior of velocity profile under the influence of different frequency (34, 48, 65 and 80 Hz in each of the upper and lower annulus of Can Combustor.An experimental rig was designed to simulate the annulus flow inside a Can Combustor.The Can Combustor tested in this study is real part collected from Al-Khairat/Iraq gas turbine power station.The velocity profiles are investigated at three positions in the annular for upper and lower region.The axial velocity and turbulence intensity are calculating with different frequency for upper and lower annulus.The results were shown that the increase of frequency lead to increase the velocity profile and large recirculation zone will build in some points.Reynolds number increasing with raise of axial velocity. Also the increasing in vibration level cause non-uniform velocity profile which affect on distribution of cooling effectiveness.

  19. 76 FR 21383 - Proposed Collection; Comment Request; Food Reporting Comparison Study (FORCS) and Food and Eating...

    2011-04-15

    ... DEPARTMENT OF HEALTH AND HUMAN SERVICES National Institutes of Health Proposed Collection; Comment Request; Food Reporting Comparison Study (FORCS) and Food and Eating Assessment Study (FEAST) (NCI... Collection: Title: Food Reporting Comparison Study (FORCS) and Food and Eating Assessment Study (FEAST) (NCI...

  20. Study of stream flow effects on bubble motion

    Sami, S.S.

    1983-01-01

    The formation of air bubbles at constant-pressure by submerged orifices was investigated in both quiescent and moving streams inside a vertical tube. Parameters affecting the bubble rise velocity, such as bubble generating frequency and diameter, were studied and analyzed for bubbles rising in a chain and homogeneous mixture. A special technique for measuring bubble motion parameters has been developed, tested, and employed throughout the experimental investigation. The method is based on a water-air impedance variation. Results obtained in stagnant liquid show that increasing the bubble diameter serves to increase bubble rise velocity, while an opposite trend has been observed for stream liquid where the bubble diameter increase reduces the bubble rise velocity. The increase of bubble generation frequency generally increases the bubble rise velocity. Experimental data covered with bubble radial distribution showed symmetrical profiles of bubble velocity and frequency, and the radial distribution of the velocity profiles sometimes has two maxima and one minimum depending on the liquid velocity. Finally, in stagnant liquid, a normalized correlation has been developed to predict the terminal rise velocity in terms of bubble generating frequency, bubble diameter, single bubble rise velocity, and conduit dimensions. Another correlation is presented for forced bubbly flow, where the bubble rise velocity is expressed as a function of bubble generating frequency, bubble diameter, and water superficial velocity

  1. Laserspectroscopic studies of collective properties of neutron deficient Ba nuclei

    Bekk, K.; Andl, A.; Goering, S.; Hanser, A.; Nowicki, G.; Rebel, H.; Schatz, G.

    1979-01-01

    Isotope shifts and hyperfine structure of the BaI resonance-line (lambda=553.6 nm) have been measured by dye laser induced resonance fluorescence on an atomic beam for sup(135m,129g,129m,126) Ba thus extending previous high resolution measurements of neutron deficient Ba nuclides (N - isomers sup(135m) Ba and sup(135m) Ba show a decreased staggering. Conspicuously the isomer shift of the g 7/2 + isomer sup(129m) Ba proves to be negative. The nuclear structure information is discussed in the context of gamma-spectroscopic studies of transitional nuclei with 50 [de

  2. Metabolism of labeled parathyroid hormone. V. Collected biological studies

    Neuman, W F; Neuman, M W; Lane, K; Miller, L; Sammon, P J

    1975-01-01

    Biologically active /sup 125/I-labeled parathyroid hormone (/sup 125/I-PTH) was used in a series of studies in dogs and chickens designed to confirm and augment earlier studies in rats. As in rats, a three exponential equation was required to describe disappearance of /sup 125/I-PTH from the blood in the dog. The first two ''half-lives'' (1.8 and 7 min) accounted for the bulk of the dose. Also as in rats, deposition of apparently intact hormone took place rapidly in kidney, liver and bone in both the dog and the chicken. Degradation occurred very rapidly in all three target organs. Three labeled hormones of different biological activities were compared in the rat. Inactive, oxidized hormone was rejected by the liver but showed markedly increased deposition in kidney and the higher the purity of the hormone the higher was its uptake by liver. Exploration of a wide range of dosages revealed few effects on distribution (smaller depositon in liver and kidney at highest dosages, 65 ..mu..g/rat). Fresh sera did not degrade hormone rapidly or extensively. There was no deposition of hormone in intestinal mucosa, marrow, and red cells. Nephrectomy increased deposition in liver and bone. Finally, the perfused liver was capable of extensive degradation of the hormone.

  3. Assessing the degree of plug flow in oxidation flow reactors (OFRs): a study on a potential aerosol mass (PAM) reactor

    Mitroo, Dhruv; Sun, Yujian; Combest, Daniel P.; Kumar, Purushottam; Williams, Brent J.

    2018-03-01

    Oxidation flow reactors (OFRs) have been developed to achieve high degrees of oxidant exposures over relatively short space times (defined as the ratio of reactor volume to the volumetric flow rate). While, due to their increased use, attention has been paid to their ability to replicate realistic tropospheric reactions by modeling the chemistry inside the reactor, there is a desire to customize flow patterns. This work demonstrates the importance of decoupling tracer signal of the reactor from that of the tubing when experimentally obtaining these flow patterns. We modeled the residence time distributions (RTDs) inside the Washington University Potential Aerosol Mass (WU-PAM) reactor, an OFR, for a simple set of configurations by applying the tank-in-series (TIS) model, a one-parameter model, to a deconvolution algorithm. The value of the parameter, N, is close to unity for every case except one having the highest space time. Combined, the results suggest that volumetric flow rate affects mixing patterns more than use of our internals. We selected results from the simplest case, at 78 s space time with one inlet and one outlet, absent of baffles and spargers, and compared the experimental F curve to that of a computational fluid dynamics (CFD) simulation. The F curves, which represent the cumulative time spent in the reactor by flowing material, match reasonably well. We value that the use of a small aspect ratio reactor such as the WU-PAM reduces wall interactions; however sudden apertures introduce disturbances in the flow, and suggest applying the methodology of tracer testing described in this work to investigate RTDs in OFRs to observe the effect of modified inlets, outlets and use of internals prior to application (e.g., field deployment vs. laboratory study).

  4. Assessing the degree of plug flow in oxidation flow reactors (OFRs: a study on a potential aerosol mass (PAM reactor

    D. Mitroo

    2018-03-01

    Full Text Available Oxidation flow reactors (OFRs have been developed to achieve high degrees of oxidant exposures over relatively short space times (defined as the ratio of reactor volume to the volumetric flow rate. While, due to their increased use, attention has been paid to their ability to replicate realistic tropospheric reactions by modeling the chemistry inside the reactor, there is a desire to customize flow patterns. This work demonstrates the importance of decoupling tracer signal of the reactor from that of the tubing when experimentally obtaining these flow patterns. We modeled the residence time distributions (RTDs inside the Washington University Potential Aerosol Mass (WU-PAM reactor, an OFR, for a simple set of configurations by applying the tank-in-series (TIS model, a one-parameter model, to a deconvolution algorithm. The value of the parameter, N, is close to unity for every case except one having the highest space time. Combined, the results suggest that volumetric flow rate affects mixing patterns more than use of our internals. We selected results from the simplest case, at 78 s space time with one inlet and one outlet, absent of baffles and spargers, and compared the experimental F curve to that of a computational fluid dynamics (CFD simulation. The F curves, which represent the cumulative time spent in the reactor by flowing material, match reasonably well. We value that the use of a small aspect ratio reactor such as the WU-PAM reduces wall interactions; however sudden apertures introduce disturbances in the flow, and suggest applying the methodology of tracer testing described in this work to investigate RTDs in OFRs to observe the effect of modified inlets, outlets and use of internals prior to application (e.g., field deployment vs. laboratory study.

  5. Quantitative measurement of portal blood flow by magnetic resonance phase contrast. Comparative study of flow phantom and Doppler ultrasound in vivo

    Tsunoda, Masatoshi; Kimoto, Shin; Hamazaki, Keisuke; Takeda, Yoshihiro; Hiraki, Yoshio.

    1994-01-01

    A non-invasive method for measuring portal blood flow by magnetic resonance (MR) phase contrast was evaluated in a flow phantom and 20 healthy volunteers. In a flow phantom study, the flow volumes and mean flow velocities measured by MR phase contrast showed close correlations with those measured by electromagnetic flow-metry. In 20 healthy volunteers, the cross-sectional areas, flow volumes and mean flow velocities measured by MR phase contrast correlated well with those measured by the Doppler ultrasound method. Portal blood flow averaged during the imaging time could be measured under natural breathing conditions by using a large number of acquisitions without the limitations imposed on the Doppler ultrasound method. MR phase contrast is considered to be useful for the non-invasive measurement of portal blood flow. (author)

  6. Liquid-vapor phase transition, collective flow and entropy determination from future measurements of intermediate mass fragments

    Coffin, J.P.

    1991-01-01

    Some global variables reflecting the highly collective character of nuclear matter produced in relativistic heavy-ion collisions are briefly reviewed on the basis of presently available experimental results and of Quantum Statistical Model and Quantum Molecular Dynamic Model predictions relative to intermediate mass fragments. Possible future measurements are suggested. (author) 27 refs., 8 figs

  7. Experimental study on interfacial area transport in downward two-phase flow

    Wang, Guanyi

    In view of the importance of two group interfacial area transport equations and lack of corresponding accurate downward flow database that can reveal two group interfacial area transport, a systematic database for adiabatic, air-water, vertically downward two-phase flow in a round pipe with inner diameter of 25.4 mm was collected to gain an insight of interfacial structure and provide benchmarking data for two-group interfacial area transport models. A four-sensor conductivity probe was used to measure the local two phase flow parameters and data was collected with data sampling frequency much higher than conventional data sampling frequency to ensure the accuracy. Axial development of local flow parameter profiles including void fraction, interfacial area concentration, and Sauter mean diameter were presented. Drastic inter-group transfer of void fraction and interfacial area was observed at bubbly to slug transition flow. And the wall peaked interfacial area concentration profiles were observed in churn-turbulent flow. The importance of local data about these phenomenon on flow structure prediction and interfacial area transport equation benchmark was analyzed. Bedsides, in order to investigate the effect of inlet conditions, all experiments were repeated after installing the flow straightening facility, and the results were briefly analyzed. In order to check the accuracy of current data, the experiment results were cross-checked with rotameter measurement as well as drift-flux model prediction, the averaged error is less than 15%. Current models for two-group interfacial area transport equation were evaluated using these data. The results show that two-group interfacial area transport equations with current models can predict most flow conditions with error less than 20%, except some bubbly to slug transition flow conditions and some churn-turbulent flow conditions. The disagreement between models and experiments could result from underestimate of inter

  8. Preferential Flow Paths In A Karstified Spring Catchment: A Study Of Fault Zones As Conduits To Rapid Groundwater Flow

    Kordilla, J.; Terrell, A. N.; Veltri, M.; Sauter, M.; Schmidt, S.

    2017-12-01

    In this study we model saturated and unsaturated flow in the karstified Weendespring catchment, located within the Leinetal graben in Goettingen, Germany. We employ the finite element COMSOL Multiphysics modeling software to model variably saturated flow using the Richards equation with a van Genuchten type parameterization. As part of the graben structure, the Weende spring catchment is intersected by seven fault zones along the main flow path of the 7400 m cross section of the catchment. As the Weende spring is part of the drinking water supply in Goettingen, it is particularly important to understand the vulnerability of the catchment and effect of fault zones on rapid transport of contaminants. Nitrate signals have been observed at the spring only a few days after the application of fertilizers within the catchment at a distance of approximately 2km. As the underlying layers are known to be highly impermeable, fault zones within the area are likely to create rapid flow paths to the water table and the spring. The model conceptualizes the catchment as containing three hydrogeological limestone units with varying degrees of karstification: the lower Muschelkalk limestone as a highly conductive layer, the middle Muschelkalk as an aquitard, and the upper Muschelkalk as another conductive layer. The fault zones are parameterized based on a combination of field data from quarries, remote sensing and literary data. The fault zone is modeled considering the fracture core as well as the surrounding damage zone with separate, specific hydraulic properties. The 2D conceptual model was implemented in COMSOL to study unsaturated flow at the catchment scale using van Genuchten parameters. The study demonstrates the importance of fault zones for preferential flow within the catchment and its effect on the spatial distribution of vulnerability.

  9. Flow visualization study of two-phase flow in a single bend outlet feeder pipe of a CANDU reactor

    Savalaxs, S.-A.; Lister, D.H.; Steward, F.R.

    2005-01-01

    In CANDU reactors, the feeder piping that is used to direct the high-temperature water coolant between the fuel channels and the steam generators is made of carbon steel. Since 1996, several CANDU stations have reported excessive corrosion of their outlet feeders. The first metre is particularity vulnerable because the piping there consists of single or double bends, which have relatively thin walls produced by the bending process. Early studies related the attack to the hydrodynamics of the coolant and verified that it was a type of flow-accelerated corrosion. In order to understand the hydrodynamics of the coolant in the outlet feeders by flow visualization, a full-scale transparent test section simulating the geometry and orientation of an outlet feeder bend with its upstream components was fabricated. The feeder consisted of a 54 mm diameter acrylic pipe with a 73 degree bend. This was connected to the upstream component with an acrylic simulation of a Grayloc flanged fitting. A test loop supplied room temperature water to the test section at flow rates up to 0.019 m3/s. Air could be injected into the water to give a mean volume fraction of up to 0.56. In this preliminary investigation, the size and velocity of air bubbles at different flow conditions and their distribution within the pipe bend were studied. Particular attention was paid to the flow pattern at the inside of the bend, where a CFD (computational fluid dynamics) code - Fluent 6.1-had failed to predict a liquid film in an earlier study. A high-speed digital video camera was used to determine the relation between bubble size and velocity. Such a relation should help to explain the discrepancy in the CFD modelling and provide the basis for accurate predictions of phase distribution in complex geometries at high flow rates. (authors)

  10. A study of stratified gas-liquid pipe flow

    Johnson, George W.

    2005-07-01

    This work includes both theoretical modelling and experimental observations which are relevant to the design of gas condensate transport lines. Multicomponent hydrocarbon gas mixtures are transported in pipes over long distances and at various inclinations. Under certain circumstances, the heavier hydrocarbon components and/or water vapour condense to form one or more liquid phases. Near the desired capacity, the liquid condensate and water is efficiently transported in the form of a stratified flow with a droplet field. During operating conditions however, the flow rate may be reduced allowing liquid accumulation which can create serious operational problems due to large amounts of excess liquid being expelled into the receiving facilities during production ramp-up or even in steady production in severe cases. In particular, liquid tends to accumulate in upward inclined sections due to insufficient drag on the liquid from the gas. To optimize the transport of gas condensates, a pipe diameters should be carefully chosen to account for varying flow rates and pressure levels which are determined through the knowledge of the multiphase flow present. It is desirable to have a reliable numerical simulation tool to predict liquid accumulation for various flow rates, pipe diameters and pressure levels which is not presently accounted for by industrial flow codes. A critical feature of the simulation code would include the ability to predict the transition from small liquid accumulation at high flow rates to large liquid accumulation at low flow rates. A semi-intermittent flow regime of roll waves alternating with a partly backward flowing liquid film has been observed experimentally to occur for a range of gas flow rates. Most of the liquid is transported in the roll waves. The roll wave regime is not well understood and requires fundamental modelling and experimental research. The lack of reliable models for this regime leads to inaccurate prediction of the onset of

  11. Experimental study on the rheological behaviour of debris flow

    A. Scotto di Santolo

    2010-12-01

    Full Text Available A model able to describe all the processes involved in a debris flow can be very complex owing to the sudden changing of the material that turns from solid into liquid state. The two phases of the phenomenon are analysed separately referring to soil mechanics procedures with regard to the trigger phase, and to an equivalent fluid for the post-failure phase. The present paper is devoted to show the experimental results carried out to evaluate the behaviour assumed by a pyroclastic-derived soil during the flow. A traditional fluid tool has been utilized: a standard rotational rheometer equipped with two different geometries. The soils tested belong to deposits that cover the slopes of the Campania region, Italy, often affected by debris flows. The influence of solid concentration Cv and grain size distribution was tested: the soils were destructurated, sieved and mixed with water starting from the in situ porosity. All material mixtures showed a non-Newtonian fluid behaviour with a yield stress τy that increases with a solid volumetric concentration and decreases for an increase of sand fraction. The experimental data were fitted with standard model for fluids. A simple relation between Cv and τy was obtained. The yield stress seems to be a key parameter for describing and predicting the post-failure behaviour of debris flows. These results suggest that in the field a small change in solid fraction, due to rainfall, will cause a slight decrease of the static yield stress, readily inducing a rapid flow which will stop only when the dynamic yield stress is reached, namely on a much smoother slope. This can explain the in situ observed post-failure behaviour of debris flows, which are able to flow over very long distances even on smooth slopes.

  12. Modeling and numerical study of two phase flow

    Champmartin, A.

    2011-01-01

    This thesis describes the modelization and the simulation of two-phase systems composed of droplets moving in a gas. The two phases interact with each other and the type of model to consider directly depends on the type of simulations targeted. In the first part, the two phases are considered as fluid and are described using a mixture model with a drift relation (to be able to follow the relative velocity between the two phases and take into account two velocities), the two-phase flows are assumed at the equilibrium in temperature and pressure. This part of the manuscript consists of the derivation of the equations, writing a numerical scheme associated with this set of equations, a study of this scheme and simulations. A mathematical study of this model (hyperbolicity in a simplified framework, linear stability analysis of the system around a steady state) was conducted in a frame where the gas is assumed baro-tropic. The second part is devoted to the modelization of the effect of inelastic collisions on the particles when the time of the simulation is shorter and the droplets can no longer be seen as a fluid. We introduce a model of inelastic collisions for droplets in a spray, leading to a specific Boltzmann kernel. Then, we build caricatures of this kernel of BGK type, in which the behavior of the first moments of the solution of the Boltzmann equation (that is mass, momentum, directional temperatures, variance of the internal energy) are mimicked. The quality of these caricatures is tested numerically at the end. (author) [fr

  13. UAV-based remote sensing surveys of lava flow fields: a case study from Etna's 1974 channel-fed lava flows

    Favalli, Massimiliano; Fornaciai, Alessandro; Nannipieri, Luca; Harris, Andrew; Calvari, Sonia; Lormand, Charline

    2018-03-01

    During an eruption, time scales of topographic change are fast and involve vertical and planimetric evolution of millimeters to meters as the event progresses. Repeat production of high spatial resolution terrain models of lava flow fields over time scales of a few hours is thus a high-value capability in tracking the buildup of the deposit. Among the wide range of terrestrial and aerial methods available to collect such topographic data, the use of an unmanned aerial vehicle (UAV) as an acquisition platform, together with structure from motion (SfM) photogrammetry, has become especially useful. This approach allows high-frequency production of centimeter-scale terrain models over kilometer-scale areas, including dangerous and inaccessible zones, with low cost and minimal hazard to personnel. This study presents the application of such an integrated UAV-SfM method to generate a high spatial resolution digital terrain model and orthomosaic of Mount Etna's January-February 1974 lava flow field. The SfM method, applied to images acquired using a UAV platform, enabled the extraction of a very high spatial resolution (20 cm) digital elevation model and the generation of a 3-cm orthomosaic covering an area of 1.35 km2. This spatial resolution enabled us to analyze the morphology of sub-meter-scale features, such as folds, blocks, and cracks, over kilometer-scale areas. The 3-cm orthomosaic allowed us to further push the analysis to centimeter-scale grain size distribution of the lava surface. Using these data, we define three types of crust structure and relate them to positions within a channel-fed ´áā flow system. These crust structures are (i) flow parallel shear lines, (ii) raft zones, and (iii) folded zones. Flow parallel shear lines are found at the channel edges, and are 2-m-wide and 0.25-m-deep zones running along the levee base and in which cracking is intense. They result from intense shearing between the moving channel lava and the static levee lava. In

  14. An experimental study on two-phase flow pattern in low pressure natural circulation system

    Wu Shaorong; Han Bing; Zhou Lei; Zhang Youjie; Jiang Shengyao; Wu Xinxin

    1991-10-01

    An experimental study on two-phase flow pattern in the riser of low pressure natural circulation system was performed. The local differential pressure signal was analysed for flow pattern. It is considered that Sr f·d/v can be used to distinguish different flow patterns and it has clear and definite physical meaning. Flow patterns at different inlet temperature with different system pressures (1.5 MPa, 0.24 MPa and 0.1 MPa) are described. It is considered that the flow pattern is only bubble flow without flow pattern change during the period of low quality density-wave instability at 1.5 MPa. There is no density-wave oscillation in the system, when flow pattern is in bubble-intermittent transition area. The effect of flash vaporization on stability at low pressure is discussed

  15. Performance of Reynolds Averaged Navier-Stokes Models in Predicting Separated Flows: Study of the Hump Flow Model Problem

    Cappelli, Daniele; Mansour, Nagi N.

    2012-01-01

    Separation can be seen in most aerodynamic flows, but accurate prediction of separated flows is still a challenging problem for computational fluid dynamics (CFD) tools. The behavior of several Reynolds Averaged Navier-Stokes (RANS) models in predicting the separated ow over a wall-mounted hump is studied. The strengths and weaknesses of the most popular RANS models (Spalart-Allmaras, k-epsilon, k-omega, k-omega-SST) are evaluated using the open source software OpenFOAM. The hump ow modeled in this work has been documented in the 2004 CFD Validation Workshop on Synthetic Jets and Turbulent Separation Control. Only the baseline case is treated; the slot flow control cases are not considered in this paper. Particular attention is given to predicting the size of the recirculation bubble, the position of the reattachment point, and the velocity profiles downstream of the hump.

  16. Effect of Pedestrians on the Saturation Flow Rate of Right Turn Movements at Signalized Intersection - Case Study from Rasht City

    Roshani, Mostafa; Bargegol, Iraj

    2017-10-01

    Saturation flow rate is one of the important items in the analysis of the capacity of signalized intersections that are affected by some factors. Pedestrian crossing on signalized intersection is one of the factors which influence the vehicles flow. In addition, the released researches determined that the greatest impact of pedestrian on the saturation flow occurred in the Conflict zone where the highest chance of the encounter of pedestrians and vehicles has in turning movements. The purpose of this paper is to estimate the saturation flow rate considering the effect of a pedestrian on right turn movements of the signalized intersections in Rasht city. For this goal, 6 signalized intersections with 90 cycles of reviews were selected for the estimation of saturation flow rate by the microscopic method and also 3 right turn lanes containing radius differences with 70 cycles of reviews were collected for the investigation of the pedestrians’ effects. Each phase of right turn lanes cycle was divided in the pieces of 10-second period which was totally 476 sample volumes of considered pedestrians and vehicles at that period. Only 101 samples of those were ranged as saturated conditions. Finally, using different regression models, the best relationship between pedestrian’s volume and right turning vehicles flow parameters was evaluated. The results indicate that there is a primarily linear relationship between pedestrian volume and right turning vehicles flow with R2=0.6261. According to this regression model with the increase in pedestrians, saturation flow rate will be reduced. In addition, by comparing the adjustment factor obtained in the present study and other studies, it was found that the effect of pedestrians on the right-turn movements in Rasht city is less than the rest of the world.

  17. Experimental Studies of Acoustics in a Spherical Couette Flow

    Gowen, Savannah; Adams, Matthew; Stone, Douglas; Lathrop, Daniel

    2016-11-01

    The Earth, like many other astrophysical bodies, contains turbulent flows of conducting fluid which are able to sustain magnetic field. To investigate the hydromagnetic flow in the Earth's outer core, we have created an experiment which generates flows in liquid sodium. However, measuring these flows remains a challenge because liquid sodium is opaque. One possible solution is the use of acoustic waves. Our group has previously used acoustic wave measurements in air to infer azimuthal velocity profiles, but measurements attempted in liquid sodium remain challenging. In the current experiments we measure acoustic modes and their mode splittings in both air and water in a spherical Couette device. The device is comprised of a hollow 30-cm outer sphere which contains a smaller 10-cm rotating inner sphere to drive flow in the fluid in between. We use water because it has material properties that are similar to those of sodium, but is more convenient and less hazardous. Modes are excited and measured using a speaker and microphones. Measured acoustic modes and their mode splittings correspond well with the predicted frequencies in air. However, water modes are more challenging. Further investigation is needed to understand acoustic measurements in the higher density media.

  18. Maintaining turbidity and current flow in laboratory aquarium studies, a case study using Sabellaria spinulosa

    Davies, Andrew J.; S. Last, Kim; Attard, Karl

    2009-01-01

    RT) is a simple and reliable system for the resuspension of food or sediments using an enclosed airlift. The particle rain from the lift is mixed in the tank by two water inputs that provide directional current flow across the study organism(s). The vortex mixing creates a turbulent lateral water flow that allows......Many aquatic organisms rely on the suspension of particulate matter for food or for building materials, yet these conditions are difficult to replicate in laboratory mesocosms. Consequently, husbandry and experimental conditions may often be sub-optimal. The Vortex Resuspension Tank (Vo...... the distribution of particulate matter outwards from the sediment outflow. By calibrating a VoRT it is possible to control sedimentation rate by manipulating water and air flow rates. As an example application, three VoRTs were maintained under different sediment loadings to assess the sediment fraction...

  19. Experimental study of flow monitoring instruments in air-water, two-phase downflow

    Sheppard, J.D.; Hayes, P.H.; Wynn, M.C.

    1976-01-01

    The performance of a turbine meter, target flow meter (drag disk), and a gamma densitometer was studied in air-water, two-phase vertical downflow. Air and water were metered into an 0.0889-m-ID (3.5-in.) piping system; air flows ranged from 0.007 to 0.3 m 3 /sec (16 to 500 scfm) and water flows ranged from 0.0006 to 0.03 m 3 /sec (10 to 500 gpm). The study included effects of flow rate, quality, flow regime, and flow dispersion on the mean and fluctuating components of the instrument signals. Wire screen flow dispersers located at the inlet to the test section had a significant effect on the readings of the drag disk and gamma densitometer, but had little effect on the turbine. Further, when flow dispersers were used, mass flow rates determined from the three instrument readings and a two-velocity, slip flow model showed good agreement with actual mass flow rate over a three-fold range in quality; mass flows determined with the drag disk and densitometer readings assuming homogeneous flow were nearly as accurate. However, when mass flows were calculated using the turbine and densitometer or turbine and drag disk readings assuming homogeneous flow, results were scattered and relatively inaccurate compared to the actual mass flows. Turbine meter data were used with a two-velocity turbine model and continuity relationships for each phase to determine the void fraction and mean phase velocities in the test section. The void fraction was compared with single beam gamma densitometer results and fluid momentum calculated from a two-velocity model was compared with drag disk readings

  20. Pseudorapidity and Centrality Dependence of the Collective Flow of Charged Particles in Au+Au Collisions at (sNN)=130 GeV

    Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Henderson, C.; Hofman, D.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    2002-11-01

    This paper describes the measurement of collective flow for charged particles in Au+Au collisions at (sNN)=130 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). The measured azimuthal hit anisotropy is presented over a wide range of pseudorapidity (-5.0<η<5.3) for the first time at this energy. The result, averaged over momenta and particle species, is observed to reach 7% for peripheral collisions at midrapidity, falling off with centrality and increasing |η|. These results call into question the common assumption of longitudinal boost invariance over a large region of rapidity in RHIC collisions.

  1. A study of Two-Phase Flow Regime Maps in Vertical and Horizontal Pipes

    Kim, Kyung Doo; Kang, Doo Hyuk

    2007-10-01

    A safety analysis code to design a pressurized water reactor and to obtain the licences including entire proprietary rights is under development in domestic research and development project. The purpose and scope of this report is to develop the flow regimes related models for inter-phase friction, wall frictions, wall heat transfer, and inter-phase heat and mass transfer in two-phase three-field equations. In order to choose choose the flow regime criteria, we have investigated various exiting best-estimate T/H codes in this chapter 2. They are the RELAP5-3D, TRAC-M, CATHARE, MARS codes. Around 500 references used in these codes have been collected and reviewed. Also we have investigated eleven papers in detail. In chapter 3, based on the selected flow regimes, the flow regime maps for a gas-liquid flow in horizontal and vertical tubes have decided including the mechanisms of flow regime transition regions. Conclusively, the process will be presented for choosing the best flow regime maps which occur in gas-liquid two-phase flow in horizontal and vertical pipes. We will look forward to decide the constitutive relations based upon the flow regime maps that are determined in this works. The constitutive relations will be used for the code under development

  2. A numerical study on buoyancy-driven flow in an inclined square enclosure heated and cooled on adjacent walls

    Aydin, O.; Uenal, A.; Ayhan, T.

    1999-01-01

    Buoyancy-driven flows in enclosures play a vital role in many engineering applications such as double glazing, ventilation of rooms, nuclear reactor insulation, solar energy collection, cooling of electronic components, and crystal growth in liquids. Here, numerical study on buoyancy-driven laminar flow in an inclined square enclosure heated from one side and cooled from the adjacent side is conducted using finite difference methods. The effect of inclination angle on fluid flow and heat transfer is investigated by varying the angle of inclination between 0 degree and 360degree, and the results are presented in the form of streamlines and isotherms for different inclination angles and Rayleigh numbers. On the basis of the numerical data, the authors determine the critical values of the inclination angle at which the rate of the transfer within the enclosure is either maximum or minimum

  3. Evaluation of salivary glucose, IgA and flow rate in diabetic patients: a case-control study.

    Bakianian Vaziri, P; Vahedi, M; Mortazavi, H; Abdollahzadeh, Sh; Hajilooi, M

    2010-01-01

    An association between diabetes mellitus and alterations in the oral cavity has been noted. In this study, we evaluated differences between salivary IgA, glucose and flow rate in diabetic patients compared with healthy controls. Forty patients with type 1 diabetes, 40 patients with type 2 diabetes and 40 healthy controls were selected. Whole unstimulated saliva samples were collected by the standard method and the salivary flow rate was determined. Nephelometric and Pars method were used to measure salivary IgA and salivary glucose concentrations, respectively. Statistical analysis was performed by Chi-square and t test. There were no significant differences in salivary IgA and glucose concentrations between type 1 and type 2 diabetic patients and their matched control subjects (P>0.05). Salivary flow rate was significantly lower in diabetic patients (Pdiabetic patients than the controls. Determination of salivary constituents may be useful in the description and management of oral findings in diabetic patients.

  4. Study on groundwater flow system in a sedimentary rock area. Case study for the Yoro river basin, Chiba Prefecture

    Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo

    2007-01-01

    In the safety assessment for a geological disposal of long-lived radioactive waste such as high-level radioactive waste and TRU waste etc, it is important to estimate radionuclide migration to human society associated with groundwater flow. Groundwater flow systems for many domestic areas including Tono Mine, Kamaishi Mine and Horonobe district have been studied, but deep groundwater flow circumstances, and mixing between deep groundwater and shallow groundwater flow system are not well understood. Japan Atomic Energy Agency (JAEA) has started to investigate a sedimentary rock area in the Yoro river basin, in Chiba Prefecture, where the topographic and geological features are relatively simple for mathematical modeling, and hydraulic data as well as data from river and well water are available. Hydro-chemical conditions of the regional groundwater were discussed based on temperature, chemical compositions, isotopic ratios of hydrogen and oxygen, and the isotopic age of radioactive carbon for water samples collected from wells, rivers and springs in the Yoro river basin. It was found that the groundwater system in this basin consists of types of water: Ca-HCO 3 type water, Na-HCO 3 type water and NaCl type water. The Ca-HCO 3 type water is meteoric water cultivated several thousand years or after, the Na-HCO 3 type water is meteoric water cultivated under cold climates several to twenty thousand years ago. The NaCl type water is fossil brine water formed twenty thousand years ago. It was also observed that the Na-HCO 3 type water upwelled at the surface originates from GL-200m to -400m. This observation indicates that the Na-HCO 3 type water upwelled through the Ca-HCO 3 type water area with the both waters partially mixed. (author)

  5. Development of a setup to enable stable and accurate flow conditions for membrane biofouling studies

    Bucs, Szilard

    2015-07-10

    Systematic laboratory studies on membrane biofouling require experimental conditions that are well defined and representative for practice. Hydrodynamics and flow rate variations affect biofilm formation, morphology, and detachment and impacts on membrane performance parameters such as feed channel pressure drop. There is a suite of available monitors to study biofouling, but systems to operate monitors have not been well designed to achieve an accurate, constant water flow required for a reliable determination of biomass accumulation and feed channel pressure drop increase. Studies were done with membrane fouling simulators operated in parallel with manual and automated flow control, with and without dosage of a biodegradable substrate to the feedwater to enhance biofouling rate. High flow rate variations were observed for the manual water flow system (up to ≈9%) compared to the automatic flow control system (<1%). The flow rate variation in the manual system was strongly increased by biofilm accumulation, while the automatic system maintained an accurate and constant water flow in the monitor. The flow rate influences the biofilm accumulation and the impact of accumulated biofilm on membrane performance. The effect of the same amount of accumulated biomass on the pressure drop increase was related to the linear flow velocity. Stable and accurate feedwater flow rates are essential for biofouling studies in well-defined conditions in membrane systems. © 2015 Balaban Desalination Publications. All rights reserved.

  6. Holographic aids for internal combustion engine flow studies

    Regan, C.

    1984-01-01

    Worldwide interest in improving the fuel efficiency of internal combustion (I.C.) engines has sparked research efforts designed to learn more about the flow processes of these engines. The flow fields must be understood prior to fuel injection in order to design efficient valves, piston geometries, and fuel injectors. Knowledge of the flow field is also necessary to determine the heat transfer to combustion chamber surfaces. Computational codes can predict velocity and turbulence patterns, but experimental verification is mandatory to justify their basic assumptions. Due to their nonintrusive nature, optical methods are ideally suited to provide the necessary velocity verification data. Optical sytems such as Schlieren photography, laser velocimetry, and illuminated particle visualization are used in I.C. engines, and now their versatility is improved by employing holography. These holographically enhanced optical techniques are described with emphasis on their applications in I.C. engines.

  7. Research on stochastic power-flow study methods. Final report

    Heydt, G. T. [ed.

    1981-01-01

    A general algorithm to determine the effects of uncertainty in bus load and generation on the output of conventional power flow analysis is presented. The use of statistical moments is presented and developed as a means for representing the stochastic process. Statistical moments are used to describe the uncertainties, and facilitate the calculations of single and multivarlate probability density functions of input and output variables. The transformation of the uncertainty through the power flow equations is made by the expansion of the node equations in a multivariate Taylor series about an expected operating point. The series is truncated after the second order terms. Since the power flow equations are nonlinear, the expected values of output quantities is in general not the solution to the conventional load flow problem using expected values of input quantities. The second order transformation offers a correction vector and allows the consideration of larger uncertainties which have caused significant error in the current linear transformation algorithms. Voltage controlled busses are included with consideration of upper and lower limits. The finite reactive power available at generation sites, and fixed ranges of transformer tap movement may have a significant effect on voltage and line power flow statistics. A method is given which considers limitation constraints in the evaluation of all output quantities. The bus voltages, line power flows, transformer taps, and generator reactive power requirements are described by their statistical moments. Their values are expressed in terms of the probability that they are above or below specified limits, and their expected values given that they do fall outside the limits. Thus the algorithm supplies information about severity of overload as well as probability of occurrence. An example is given for an eleven bus system, evaluating each quantity separately. The results are compared with Monte Carlo simulation.

  8. Geophysical data collected during the 2014 minute 319 pulse flow on the Colorado River below Morelos Dam, United States and Mexico

    Kennedy, Jeffrey R.; Callegary, James B.; Macy, Jamie P.; Reyes-Lopez, Jaime; Pérez-Flores, Marco

    2017-05-09

    Geophysical methods were used to monitor infiltration during a water release, referred to as a “pulse flow,” in the Colorado River delta in March and April 2014. The pulse flow was enabled by Minute 319 of the 1944 United States–Mexico Treaty concerning water of the Colorado River. Fieldwork was carried out by the U.S. Geological Survey and the Centro de Investigación Científica y de Educación Superior de Ensenada as part of a binational effort to monitor the hydrologic effects of the pulse flow along the limitrophe (border) reach of the Colorado River and into Mexico. Repeat microgravity measurements were made at 25 locations in the southern limitrophe reach to quantify aquifer storage change during the pulse flow. Observed increases in storage along the river were greater with distance to the south, and the amount of storage change decreased away from the river channel. Gravity data at four monitoring well sites indicate specific yield equal to 0.32±0.05. Electromagnetic induction methods were used at 12 transects in the limitrophe reach of the river along the United States– Mexico border, and farther south into Mexico. These data, which are sensitive to variation in soil texture and water content, suggest relatively homogeneous conditions. Repeat direct-current resistivity measurements were collected at two locations to monitor groundwater elevation. Results indicate rapid groundwater-level rise during the pulse flow in the limitrophe reach and smaller variation at a more southern transect. Together, these data are useful for hydrogeologic characterization and hydrologic model development. Electronic data files are provided in the accompanying data release (Kennedy and others, 2016a).

  9. Validation studies for assessing unsaturated flow and transport through fractured rock

    Bassett, R.L.; Neuman, S.P.; Rasmussen, T.C.; Guzman, A.; Davidson, G.R.; Lohrstorfer, C.F.

    1994-08-01

    *The objectives of this contract are to examine hypotheses and conceptual models concerning unsaturated flow and transport through heterogeneous fractured rock and to design and execute confirmatory field and laboratory experiments to test these hypotheses and conceptual models. Important new information is presented such as the application and evaluation of procedures for estimating hydraulic, pneumatic, and solute transport coefficients for a range of thermal regimes. A field heater experiment was designed that focused on identifying the suitability of existing monitoring equipment to obtain required data. A reliable method was developed for conducting and interpreting tests for air permeability using a straddle-packer arrangement. Detailed studies of fracture flow from Queen Creek into the Magina Copper Company ore haulage tunnel have been initiated. These studies will provide data on travel time for transport of water and solute in unsaturated tuff. The collection of rainfall runoff, and infiltration data at two small watersheds at the Apache Leap Tuff Site enabled us to evaluate the quantity and rate of water infiltrating into the subsurface via either fractures or matrix. Characterization methods for hydraulic parameters relevant to Weigh-level waste transport, including fracture apertures, transmissivity, matrix porosity, and fracture wetting front propagation velocities, were developed

  10. Validation studies for assessing unsaturated flow and transport through fractured rock

    Bassett, R.L.; Neuman, S.P.; Rasmussen, T.C.; Guzman, A.; Davidson, G.R.; Lohrstorfer, C.F. [Arizona Univ., Tucson, AZ (United States). Dept. of Hydrology and Water Resources

    1994-08-01

    *The objectives of this contract are to examine hypotheses and conceptual models concerning unsaturated flow and transport through heterogeneous fractured rock and to design and execute confirmatory field and laboratory experiments to test these hypotheses and conceptual models. Important new information is presented such as the application and evaluation of procedures for estimating hydraulic, pneumatic, and solute transport coefficients for a range of thermal regimes. A field heater experiment was designed that focused on identifying the suitability of existing monitoring equipment to obtain required data. A reliable method was developed for conducting and interpreting tests for air permeability using a straddle-packer arrangement. Detailed studies of fracture flow from Queen Creek into the Magina Copper Company ore haulage tunnel have been initiated. These studies will provide data on travel time for transport of water and solute in unsaturated tuff. The collection of rainfall runoff, and infiltration data at two small watersheds at the Apache Leap Tuff Site enabled us to evaluate the quantity and rate of water infiltrating into the subsurface via either fractures or matrix. Characterization methods for hydraulic parameters relevant to Weigh-level waste transport, including fracture apertures, transmissivity, matrix porosity, and fracture wetting front propagation velocities, were developed.

  11. Salivary flow rate and oral findings in Prader-Willi syndrome: a case-control study.

    Saeves, Ronnaug; Nordgarden, Hilde; Storhaug, Kari; Sandvik, Leiv; Espelid, Ivar

    2012-01-01

    BACKGROUND. Prader-Willi syndrome (PWS) is a rare complex multisystemic genetic disorder. AIM. The objective of this study was to provide a systematic assessment of whole saliva secretion and oral manifestations associated with PWS. DESIGN. Fifty individuals (5-40 years) with PWS and an age- and sex-matched control group were included. Whole saliva was collected. All participants underwent an anamnestic interview. Radiological and dental clinical examinations were carried out to identify hypodontia, dental caries, enamel defects and gingival inflammation. RESULTS. Mean whole salivary flow rate was 0.12 ± 0.11 mL/min in the study group compared with 0.32 ± 0.20 mL/min in the control group (P 19 years was significantly lower in PWS (P = 0.04) compared with the controls. There was no significant difference in the prevalence of dental caries in the primary dentition or in the frequency of enamel defects in the permanent dentition between the two groups. Median Gingival Index was significantly higher in the Prader-Willi group compared with the controls (P = 0.02). CONCLUSIONS. Low salivary flow is a consistent finding in PWS. Nevertheless, despite dry mouth and dietary challenges, dental caries is not increased in Norwegian individuals with PWS. © 2011 The Authors. International Journal of Paediatric Dentistry © 2011 BSPD, IAPD and Blackwell Publishing Ltd.

  12. Sensitivity studies on the multi-sensor conductivity probe measurement technique for two-phase flows

    Worosz, Ted [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 230 Reber Building, University Park, PA 16802 (United States); Bernard, Matt [The United States Nuclear Regulatory Commission, 11545 Rockville Pike, Rockville, MD 20852 (United States); Kong, Ran; Toptan, Aysenur [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 230 Reber Building, University Park, PA 16802 (United States); Kim, Seungjin, E-mail: skim@psu.edu [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 230 Reber Building, University Park, PA 16802 (United States); Hoxie, Chris [The United States Nuclear Regulatory Commission, 11545 Rockville Pike, Rockville, MD 20852 (United States)

    2016-12-15

    Highlights: • Revised conductivity probe circuit to eliminate signal “ghosting” among sensors. • Higher sampling frequencies suggested for bubble number frequency and a{sub i} measurements. • Two-phase parameter sensitivity to measurement duration and bubble number investigated. • Sensors parallel to pipe wall recommended for symmetric bubble velocity measurements. • Sensor separation distance ratio (s/d) greater than four minimizes bubble velocity error. - Abstract: The objective of this study is to advance the local multi-sensor conductivity probe measurement technique through systematic investigation into several practical aspects of a conductivity probe measurement system. Firstly, signal “ghosting” among probe sensors is found to cause artificially high bubble velocity measurements and low interfacial area concentration (a{sub i}) measurements that depend on sampling frequency and sensor impedance. A revised electrical circuit is suggested to eliminate this artificial variability. Secondly, the sensitivity of the probe measurements to sampling frequency is investigated in 13 two-phase flow conditions with superficial liquid and gas velocities ranging from 1.00–5.00 m/s and 0.17–2.0 m/s, respectively. With increasing gas flow rate, higher sampling frequencies, greater than 100 kHz in some cases, are required to adequately capture the bubble number frequency and a{sub i} measurements. This trend is due to the increase in gas velocity and the transition to the slug flow regime. Thirdly, the sensitivity of the probe measurements to the measurement duration as well as the sample number is investigated for the same flow conditions. Measurements of both group-I (spherical/distorted) and group-II (cap/slug/churn-turbulent) bubbles are found to be relatively insensitive to both the measurement duration and the number of bubbles, as long as the measurements are made for a duration long enough to capture a collection of samples characteristic to a

  13. The Netherlands Epidemiology of Obesity (NEO) study: study design and data collection.

    de Mutsert, Renée; den Heijer, Martin; Rabelink, Ton Johannes; Smit, Johannes Willem Adriaan; Romijn, Johannes Anthonius; Jukema, Johan Wouter; de Roos, Albert; Cobbaert, Christa Maria; Kloppenburg, Margreet; le Cessie, Saskia; Middeldorp, Saskia; Rosendaal, Frits Richard

    2013-06-01

    Obesity is a well-established risk factor for many chronic diseases. Incomplete insight exists in the causal pathways responsible for obesity-related disorders and consequently, in the identification of obese individuals at risk of these disorders. The Netherlands Epidemiology of Obesity (NEO) study is designed for extensive phenotyping to investigate pathways that lead to obesity-related diseases. The NEO study is a population-based, prospective cohort study that includes 6,673 individuals aged 45-65 years, with an oversampling of individuals with overweight or obesity. At baseline, data on demography, lifestyle, and medical history have been collected by questionnaires. In addition, samples of 24-h urine, fasting and postprandial blood plasma and serum, and DNA were collected. Participants underwent an extensive physical examination, including anthropometry, electrocardiography, spirometry, and measurement of the carotid artery intima-media thickness by ultrasonography. In random subsamples of participants, magnetic resonance imaging of abdominal fat, pulse wave velocity of the aorta, heart, and brain, magnetic resonance spectroscopy of the liver, indirect calorimetry, dual-energy X-ray absorptiometry, or accelerometry measurements were performed. The collection of data started in September 2008 and completed at the end of September 2012. Participants are followed for the incidence of obesity-related diseases and mortality. The NEO study investigates pathways that lead to obesity-related diseases. A better understanding of the mechanisms underlying the development of disease in obesity may help to identify individuals who are susceptible to the detrimental metabolic, cardiovascular and other consequences of obesity and has implications for the development of prevention and treatment strategies.

  14. A comparison of macroscopic models describing the collective response of sedimenting rod-like particles in shear flows

    Helzel, Christiane; Tzavaras, Athanasios

    2016-01-01

    We consider a kinetic model, which describes the sedimentation of rod-like particles in dilute suspensions under the influence of gravity, presented in Helzel and Tzavaras (submitted for publication). Here we restrict our considerations to shear flow and consider a simplified situation, where the particle orientation is restricted to the plane spanned by the direction of shear and the direction of gravity. For this simplified kinetic model we carry out a linear stability analysis and we derive two different nonlinear macroscopic models which describe the formation of clusters of higher particle density. One of these macroscopic models is based on a diffusive scaling, the other one is based on a so-called quasi-dynamic approximation. Numerical computations, which compare the predictions of the macroscopic models with the kinetic model, complete our presentation.

  15. A comparison of macroscopic models describing the collective response of sedimenting rod-like particles in shear flows

    Helzel, Christiane

    2016-07-22

    We consider a kinetic model, which describes the sedimentation of rod-like particles in dilute suspensions under the influence of gravity, presented in Helzel and Tzavaras (submitted for publication). Here we restrict our considerations to shear flow and consider a simplified situation, where the particle orientation is restricted to the plane spanned by the direction of shear and the direction of gravity. For this simplified kinetic model we carry out a linear stability analysis and we derive two different nonlinear macroscopic models which describe the formation of clusters of higher particle density. One of these macroscopic models is based on a diffusive scaling, the other one is based on a so-called quasi-dynamic approximation. Numerical computations, which compare the predictions of the macroscopic models with the kinetic model, complete our presentation.

  16. Study on parallel-channel asymmetry in supercritical flow instability experiment

    Xiong Ting; Yu Junchong; Yan Xiao; Huang Yanping; Xiao Zejun; Huang Shanfang

    2013-01-01

    Due to the urgent need for experimental study on supercritical water flow instability, the parallel-channel asymmetry which determines the feasibility of such experiments was studied with the experimental and numerical results in parallel dual channel. The evolution of flow rates in the experiments was analyzed, and the steady-state characteristics as well as transient characteristics of the system were obtained by self-developed numerical code. The results show that the asymmetry of the parallel dual channel would reduce the feasibility of experiments. The asymmetry of flow rates is aroused by geometrical asymmetry. Due to the property variation characteristics of supercritical water, the flow rate asymmetry is enlarged while rising beyond the pseudo critical point. The extent of flow rate asymmetry is affected by the bulk temperature and total flow rate; therefore the experimental feasibility can be enhanced by reducing the total flow rate. (authors)

  17. Studying the gradient flow coupling in the Schroedinger functional

    Fritzsch, P. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Ramos, A. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2013-08-15

    We discuss the setup and features of a new definition of the running coupling in the Schroedinger functional scheme based on the gradient flow. Its suitability for a precise continuum limit in QCD is demonstrated on a set of N{sub f}=2 gauge field ensembles in a physical volume of L{proportional_to}0.4 fm.

  18. Numerical and Experimental Study of Electromagnetically Driven Vortical Flows

    Kenjeres, S.; Verdoold, J.; Tummers, M.J.; Hanjalic, K.; Kleijn, C.R.

    2009-01-01

    The paper reports on numerical and experimental investigations of electromagnetically driven vortical flows of an electrically conductive fluid in a generic setup. Two different configurations of permanent magnets are considered: a 3-magnet configuration in which the resulting Lorentz force is

  19. Theoretical study of flow in a thermal countercurrent centrifuge

    Durivault, Jean; Louvet, Pierre.

    1976-03-01

    This paper deals with the flow calculation in a thermal countercurrent centrifuge at total reflux. Matched asymptotic expansions are used to find approximate solutions of Navier-Stokes equations which are assumed to be valid in the whole domaine. Convection and viscous dissipation disappear because of linearization, but compressibility is taken into account. Let epsilon be the Ekman number. The equations are solved in the inviscid core, in the horizontal Ekman layers of thickness 0 (epsilonsup(1/2) and in the Stewartson layer of thickness 0 (epsilonsup(1/3)), parallel to the axis. As the thermal convection is neglected, the Stewartson layer of thickness 0 (epsilon sup(1/4)) does not occur. The results show the importance of the recirculating mass-flow rate of order 0 (epsilonsup(1/3)) in front of the countercurrent mass-flow rate of order 0 (epsilonsup(1/2)). The temperature profile rules the pattern and the intensity of the recirculating flow [fr

  20. Experimental study of water flow in nuclear fuel elements

    Rodrigues, Lorena Escriche; Rezende, Hugo Cesar; Mattos, Joao Roberto Loureiro de; Barros Filho, Jose Afonso; Santos, Andre Augusto Campagnole dos

    2013-01-01

    This work aims to develop an experimental methodology for investigating the water flow through rod bundles after spacer grids of nuclear fuel elements of PWR type reactors. Speed profiles, with the device LDV (Laser Doppler Velocimetry), and the pressure drop between two sockets located before and after the spacer grid, using pressure transducers were measured

  1. Forearm arterial anatomy and flow characteristics: a prospective observational study.

    Pancholy, Samir B; Heck, Laura A; Patel, Tejas

    2015-04-01

    Morphometric data on Caucasian radial and ulnar arteries are limited, with no data on flow interdependence in the forearm arterial circuit. A total of 250 upper extremities in 125 patients were evaluated. Ultrasonography was performed and radial and ulnar artery lumen diameters were measured. Ulnar artery (UA) was compressed at the level of the wrist, and flow parameters in radial artery (RA) were recorded using duplex Doppler ultrasound. Radial and ulnar artery diameters were comparable at the level of the distal forearm (RA = 2.03 ± 0.28 mm, UA = 2.07 ± 0.27 mm; P=.14). There was no significant difference in radial or ulnar artery diameter between the dominant upper extremity and the non-dominant upper extremity. Upon compression of the ulnar artery, radial artery velocity-time integral (VTI) increased from 8.4 ± 3.8 cm to 12.8 ± 5.5 cm, which was statistically significant (Pforearm is comparable to UA. RA-VTI and likely flow significantly increase by compression of the UA. The smaller the radial artery, the larger the increase in radial artery flow with ulnar compression.

  2. Experimental studies on the flow through soft tubes and channels

    Experiments conducted in channels/tubes with height/diameter less than. 1 mm with soft walls made ... two types of flows are very similar, the treatment of the surface is very different. The experimen- tal set-up ...... The qualitative features of the ...

  3. REVIEW Interpretation and value of MR CSF flow studies for ...

    children should be able to request this procedure from any MR imaging department, and should ... on all modern 1.5T scanners equipped with standard software and phase contrast magnetic resonance (PCMR) capabilities and analysis packages. .... Follow-up imaging demonstrates change in CSF flow to a unidirectional.

  4. Low-Flow Water Study for the Missouri River.

    2008-08-01

    The (MoDOT) retained TranSystems to identify and review low-flow industry : trends, equipment and strategies used in inland navigation settings throughout the United States and worldwide which : may be transferable to the Missouri River and which cou...

  5. Experimental study of flow patterns near tube support structures

    Rummens, H.E.C.; Turner, C.W.

    1994-07-01

    Extensive blockage of broached support plates in steam generators has occurred at the Bruce A Nuclear Generating Station (NGS), forcing unit derating in 1988 March. Blockage has also been found on the lower broached plates of the Pickering B and Point Lepreau NGSs. Water chemistry and operating conditions are known to influence fouling directly. We suspect that flow patterns also play a role, that these patterns are influenced by the geometry of steam generator (SG) components, and that particularly the broached plate design actively creates an environment favorable to deposition. Experiments are in progress to examine the flow patterns near various tube supports: the broached plate, two types of lattice bars, and the formed bars. Preliminary tests in an air/water loop with 1/2- and 7-tube SG mockups containing the tube supports have been completed. Flow patterns were visualized using injected air bubbles. Local velocities and turbulence levels were measured using a laser technique, which confirmed observations of flow recirculation and stagnation. Axial pressure profiles were measured to determine overall resistance coefficients, and to identify local pressure extremes. Some visualization tests were also carried out on an artificially fouled broached plate. Based on results to date, several deposition mechanisms are proposed: deposition of particles in stagnant regions, deposition of solubles due to flashing in low-pressure regions, and deposition in smaller channels due to steam migration toward larger channels. A qualitative assessment of the tube support designs based on these mechanisms implies that the relative resistances to fouling are: (WORST) broach plate << lattice bars << formed bars (BEST). As the air/water simulation shows only hydraulic flow patterns, further tests will be done in a simple liquid/vapor Freon loop to examine thermal effects. (author). 3 refs., 10 figs

  6. Collective design in 3D printing: A large scale empirical study of designs, designers and evolution

    Özkil, Ali Gürcan

    2017-01-01

    This paper provides an empirical study of a collective design platform (Thingiverse); with the aim of understanding the phenomenon and investigating how designs concurrently evolve through the large and complex network of designers. The case study is based on the meta-data collected from 158 489 ...

  7. Hydrodynamic modelling and global datasets: Flow connectivity and SRTM data, a Bangkok case study.

    Trigg, M. A.; Bates, P. B.; Michaelides, K.

    2012-04-01

    The rise in the global interconnected manufacturing supply chains requires an understanding and consistent quantification of flood risk at a global scale. Flood risk is often better quantified (or at least more precisely defined) in regions where there has been an investment in comprehensive topographical data collection such as LiDAR coupled with detailed hydrodynamic modelling. Yet in regions where these data and modelling are unavailable, the implications of flooding and the knock on effects for global industries can be dramatic, as evidenced by the recent floods in Bangkok, Thailand. There is a growing momentum in terms of global modelling initiatives to address this lack of a consistent understanding of flood risk and they will rely heavily on the application of available global datasets relevant to hydrodynamic modelling, such as Shuttle Radar Topography Mission (SRTM) data and its derivatives. These global datasets bring opportunities to apply consistent methodologies on an automated basis in all regions, while the use of coarser scale datasets also brings many challenges such as sub-grid process representation and downscaled hydrology data from global climate models. There are significant opportunities for hydrological science in helping define new, realistic and physically based methodologies that can be applied globally as well as the possibility of gaining new insights into flood risk through analysis of the many large datasets that will be derived from this work. We use Bangkok as a case study to explore some of the issues related to using these available global datasets for hydrodynamic modelling, with particular focus on using SRTM data to represent topography. Research has shown that flow connectivity on the floodplain is an important component in the dynamics of flood flows on to and off the floodplain, and indeed within different areas of the floodplain. A lack of representation of flow connectivity, often due to data resolution limitations, means

  8. When Are Mobile Phones Useful for Water Quality Data Collection? An Analysis of Data Flows and ICT Applications among Regulated Monitoring Institutions in Sub-Saharan Africa.

    Kumpel, Emily; Peletz, Rachel; Bonham, Mateyo; Fay, Annette; Cock-Esteb, Alicea; Khush, Ranjiv

    2015-09-02

    Water quality monitoring is important for identifying public health risks and ensuring water safety. However, even when water sources are tested, many institutions struggle to access data for immediate action or long-term decision-making. We analyzed water testing structures among 26 regulated water suppliers and public health surveillance agencies across six African countries and identified four water quality data management typologies. Within each typology, we then analyzed the potential for information and communication technology (ICT) tools to facilitate water quality information flows. A consistent feature of all four typologies was that testing activities occurred in laboratories or offices, not at water sources; therefore, mobile phone-based data management may be most beneficial for institutions that collect data from multiple remote laboratories. We implemented a mobile phone application to facilitate water quality data collection within the national public health agency in Senegal, Service National de l'Hygiène. Our results indicate that using the phones to transmit more than just water quality data will likely improve the effectiveness and sustainability of this type of intervention. We conclude that an assessment of program structure, particularly its data flows, provides a sound starting point for understanding the extent to which ICTs might strengthen water quality monitoring efforts.

  9. When Are Mobile Phones Useful for Water Quality Data Collection? An Analysis of Data Flows and ICT Applications among Regulated Monitoring Institutions in Sub-Saharan Africa

    Emily Kumpel

    2015-09-01

    Full Text Available Water quality monitoring is important for identifying public health risks and ensuring water safety. However, even when water sources are tested, many institutions struggle to access data for immediate action or long-term decision-making. We analyzed water testing structures among 26 regulated water suppliers and public health surveillance agencies across six African countries and identified four water quality data management typologies. Within each typology, we then analyzed the potential for information and communication technology (ICT tools to facilitate water quality information flows. A consistent feature of all four typologies was that testing activities occurred in laboratories or offices, not at water sources; therefore, mobile phone-based data management may be most beneficial for institutions that collect data from multiple remote laboratories. We implemented a mobile phone application to facilitate water quality data collection within the national public health agency in Senegal, Service National de l’Hygiène. Our results indicate that using the phones to transmit more than just water quality data will likely improve the effectiveness and sustainability of this type of intervention. We conclude that an assessment of program structure, particularly its data flows, provides a sound starting point for understanding the extent to which ICTs might strengthen water quality monitoring efforts.

  10. Effects of the in-medium nucleon-nucleon cross section on collective flow and nuclear stopping in heavy-ion collisions in the Fermi-energy domain

    Li, Pengcheng; Wang, Yongjia; Li, Qingfeng; Guo, Chenchen; Zhang, Hongfei

    2018-04-01

    With the newly updated version of the ultrarelativistic quantum molecular dynamics (UrQMD) model, a systematic investigation of the effects of in-medium nucleon-nucleon (NN ) elastic cross section on the collective flow and the stopping observables in 197Au+197Au collisions at beam energies from 40 to 150 MeV/nucleon is performed. Simulations with the medium correction factors F =σNN in -medium/σNN free=0.2 ,0.3 ,0.5 and the one obtained with the FU3FP1 parametrization which depends on both the density and the momentum are compared to the FOPI and INDRA experimental data. It is found that, to best fit the experimental data of the slope of the directed flow and the elliptic flow at midrapidity as well as the nuclear stopping, the correction factors of F =0.2 and 0.5 are required for reactions at beam energies of 40 and 150 MeV/nucleon, respectively. Whereas calculations with the FU3FP1 parametrization can simultaneously reproduce these experimental data reasonably well. And, the observed increasing nuclear stopping with increasing beam energy in experimental data can also be reproduced by using the FU3FP1 parametrization, whereas the calculated stopping power in Au + Au collisions with beam energies from 40 to 150 MeV /nucleon almost remains constant when taking F equal to a fixed value.

  11. Knowledge flow and exchange in interdisciplinary primary health care teams (PHCTs): an exploratory study

    Sibbald, Shannon L.; Wathen, C. Nadine; Kothari, Anita; Day, Adam M. B.

    2013-01-01

    Objective: Improving the process of evidence-based practice in primary health care requires an understanding of information exchange among colleagues. This study explored how clinically oriented research knowledge flows through multidisciplinary primary health care teams (PHCTs) and influences clinical decisions. Methods: This was an exploratory mixed-methods study with members of six PHCTs in Ontario, Canada. Quantitative data were collected using a questionnaire and analyzed with social network analysis (SNA) using UCINet. Qualitative data were collected using semi-structured interviews and analyzed with content analysis procedures using NVivo8. Results: It was found that obtaining research knowledge was perceived to be a shared responsibility among team members, whereas its application in patient care was seen as the responsibility of the team leader, usually the senior physician. PHCT members acknowledged the need for resources for information access, synthesis, interpretation, or management. Conclusion: Information sharing in interdisciplinary teams is a complex and multifaceted process. Specific interventions need to be improved such as formalizing modes of communication, better organizing knowledge-sharing activities, and improving the active use of allied health professionals. Despite movement toward team-based models, senior physicians are often gatekeepers of uptake of new evidence and changes in practice. PMID:23646028

  12. Studies for determining drain solid flow in bed silt, using radioisotope techniques

    Sanchez, W.

    1976-01-01

    A process for measuring solid flow in silt bed using isotopic technique is studied. Comparative studies for initial movement of grinded glass grains and sand grains is done. The development for determining the minimum mass of radioative grains of sand, used for flow evaluation is also studied. Further experiments in the field of reference confirm technological conditions for the method [pt

  13. Study on the petroleum recovery technology : Analysis of pipeline flow

    Kim, Se Joon; Kim, Hyun Tae; Kim, In Kee; Huh, Dae Gee [Korea Institute of Geology Mining and Materials, Taejon (Korea)

    1998-12-01

    The petroleum exploration activities have been performed by our own technology in the concession Block VI-I in Korean continental shelf for more than 10 years. Gas and gas condensate were discovered from several exploratory wells drilled in this block. This year, the news of another hit in the well of Gorae-V was very encouraging. Different from the previous gas discoveries, the reservoir properties and the productivity of Gorea-V well were excellent and the reserve estimate was very optimistic for the gas field development in this region. Gas consumption was very rapidly increased during recent years because of the image of cleaner fuel compared with other fossil fuels and convenience of usage. Korea is the fifth country in the world in terms of total quantity of petroleum consumption. This is the reason why the secure supply of oil and gas in the future is vital to our industry. The development of gas or gas condensate reservoir is different from that of oil reservoir. Especially sales contract must be made before the initiation of gas field exploitation. The production facilities including pipeline system must be selected and designed for further consideration. In this study, we have selected the 'K' offshore gas field where the water depth is 155 m and the distance from the shore is 50 km. The main purpose of this production system analysis is to select the optimum size and capacity of production facilities including pipeline in order to find the most appropriate production schedule. Production system analysis using nodal analysis includes deliverability calculation of the reservoir, production system optimization, recoverable reserve estimation, and performance forecast of the reservoir with three different production rate scenarios. The reservoir pressure is 4525 psia and the temperature is 248 deg.F. The OGIP of this reservoir was calculated as 24.64 BCF/well and the reservoir is expected to produce for up to 10 years. The porosity is 6% and the

  14. Experimental study of poloidal flow effect on magnetic island dynamics in LHD and TJ-II

    Narushima, Y.; Sakakibara, S.; Castejon, F.

    2010-11-01

    The dynamics of a magnetic island are studied by focusing on the poloidal flows in the helical devices LHD and TJ-II. The temporal increment of the ExB poloidal flow prior to the magnetic island transition from growth to healing is observed. The direction of the poloidal flow is in the electron-diamagnetic direction in LHD and in the ion-diamagnetic direction in TJ-II. From the magnetic diagnostics, it is observed that a current structure flowing in the plasma moves ∼π rad poloidally in the electron-diamagnetic direction during the transition in LHD experiments. These experimental observations from LHD and TJ-II show that the temporal increment of the poloidal flow is followed by the transition (growth to healing) of the magnetic island regardless of the flow direction and clarify the fact that significant poloidal flow affects the magnetic island dynamics. (author)

  15. Study of gene flow from GM cotton (Gossypium hirsutum) varieties in El Espinal (Tolima, Colombia)

    Rache Cardenal, Leidy Yanira; Mora Oberlaender, Julian; Chaparro Giraldo, Alejandro

    2013-01-01

    In 2009, 4088 hectares of genetically modified (GM) cotton were planted in Tolima (Colombia), however there is some uncertainty about containment measures needed to prevent the flow of pollen and seed from regulated GM fields into adjacent fields. In this study, the gene flow from GM cotton varieties to conventional or feral cotton plants via seed and pollen was evaluated. ImmunostripTM, PCR and ELISA assays were used to detect gene flow. Fifty six refuges, 27 fields with conventional cotton and four feral individuals of the enterprise Remolinos Inc. located in El Espinal (Tolima) were analyzed in the first half of 2010. The results indicated seed mediated gene flow in 45 refuges (80.4 %) and 26 fields with conventional cotton (96 %), besides pollen mediated gene flow in one field with conventional cotton and nine refuges. All fields cultivated with conventional cotton showed gene flow from GM cotton. Two refuges and two feral individuals did not reveal gene flow from GM cotton.

  16. Study of two-phase flow redistribution between two passes of a heat exchanger

    Mendes de Moura, L.F.

    1989-04-01

    The object of the present thesis deals with the study of two-phase flow redistribution between two passes of a heat exchanger. Mass flow rate measurements of each component performed at each channel outlet of the second pass allowed us to determine the influence of mass flow, gas quality, flow direction (upward or downward) and common header geometry upon flow redistribution. Local void fraction inside common header was measured with an optical probe. A two-dimensional two-phase flow computational code was developed from a two-fluid model. Modelling of interfacial momentum transfer was used in order to take into account twp-phase flow patterns in common headers. Numerical simulation results show qualitative agreement with experimental results. Present theoretical model limitations are analysed and future improvements are proposed [fr

  17. Experimental study on effects of double pumps switching on water supply flow rate

    Wang Xin; Han Weishi

    2012-01-01

    Flow characteristics in the process of switching one centrifugal pump to the other was investigated experimentally using a closed loop with two centrifugal pumps and two check valves. Characteristics of the check valves responding and the flow rate changing during the process of switching was studied by experimental data analysis. The results show that in the switching process with high and low original flow rate, the restoring time is 26 s and 21 s respectively; the lowest flow rates are 59.4% and 87.2% out of that in normal water supply, and the average deficit of feed water is 20.8% and 7.5% respectively. Compared to double-pump switching with low flow rate, a longer transition time. more intense flow fluctuations and increased water loss are observed with high flow rate, which has significantly effects on the stability of water supply. (authors)

  18. A numerical study of the complex flow structure in a compound meandering channel

    Moncho-Esteve, Ignacio J.; García-Villalba, Manuel; Muto, Yasu; Shiono, Koji; Palau-Salvador, Guillermo

    2018-06-01

    In this study, we report large eddy simulations of turbulent flow in a periodic compound meandering channel for three different depth conditions: one in-bank and two overbank conditions. The flow configuration corresponds to the experiments of Shiono and Muto (1998). The predicted mean streamwise velocities, mean secondary motions, velocity fluctuations, turbulent kinetic energy as well as mean flood flow angle to meandering channel are in good agreement with the experimental measurements. We have analyzed the flow structure as a function of the inundation level, with particular emphasis on the development of the secondary motions due to the interaction between the main channel and the floodplain flow. Bed shear stresses have been also estimated in the simulations. Floodplain flow has a significant impact on the flow structure leading to significantly different bed shear stress patterns within the main meandering channel. The implications of these results for natural compound meandering channels are also discussed.

  19. Experimental study and theoretical modelling of two-phase flow in a converging diverging nozzle

    Selmer-Olsen, Stale

    1991-01-01

    A theoretical and experimental study of high quality two-phase flows in converging-diverging nozzles is presented. The main objectives are the prediction of critical (choked) flow rates and the evolution of characteristic parameters towards the nozzle outlet. First, a thorough analysis of available models shows the importance of a correct modelling of the mechanical and thermal interactions between the gas and liquid phases. As a second step, a purely dispersed flow model is considered. The solution algorithm which is utilized describes accurately the critical (choked) flow conditions as well as the topology of the solutions. The dispersed flow model accounts for effects on the gas flow rate of the upstream and the downstream pressures, the liquid flow rate and the nozzle geometry. The pressure profile along the nozzle and the location of the critical cross-section are also well predicted. The flow is shown to switch from critical to sub-critical when the liquid flow rate is increased, all other control parameters at the inlet and the outlet maintained. This new finding is interpreted as a result of the possible location of the critical cross-section anywhere in the diverging part of the nozzle. Moreover, the experiments show that the critical (choked) gas flow rate depends on the inlet configuration of gas/liquid. In the third step, a careful analysis of the data is used as a basis for proposing a new dispersed-annular flow model. This model accounts for the liquid flowing both as a liquid film and as entrained droplets in the core, non-developed flow is accounted for as well as flow separation in the diffuser. Finally, advanced local measuring techniques of pressure, film thickness and film velocity have been developed in the course of the work. In particular film thickness measurements allowed the development of the flow structure to be understood. (author) [fr

  20. Sediment–flow interactions at channel confluences: A flume study

    Tonghuan Liu

    2015-06-01

    Full Text Available Sediment transport and bed morphology at channel confluences with different confluence angles and discharge ratios are analyzed through a series of flume experiments. Bed topography and sediment transport rate are measured and results are compared among different conditions. Sediment transport is intermittent and pulsating as the tributary flow mixes with the mainstream, and the sediment transport rate goes up with the increase in discharge ratio and confluence angle. With no sediment supplied from upstream of the flume, a central scour hole will form along the shear plane and develop toward the right bank, and the depth of the central scour hole increases as the confluence angle and discharge ratio increase. With heavy upstream sediment supplement, deposition will happen in the separation zone and upstream of the confluence area because of the tributary. And the deposition height is related to the discharge ratio and confluence angle. Results indicate the significant impact of confluence geometry, sediment, and flow factors on fluvial processes.

  1. Study of flux flow in high Tc superconductors

    Takacs, S.; Gomory, F.

    1989-01-01

    The magnetic field distribution and the hysteresis losses in superconductors with very large viscous forces are calculated for field amplitudes below and above the penetration field. Both the magnetic field and frequency dependence of the losses are changing with respect to the critical state model. The results are qualitatively confirmed by AC susceptibility measurements on YBaCuO superconductors, but the quantitative differences indicate that the flux flow effects are not so strong as expected and supposed by some theories

  2. 76 FR 59706 - Proposed Collection; Comment Request; Healthy Communities Study: How Communities Shape Children's...

    2011-09-27

    ... published in scientific journals and will be used for the development of future research initiatives... Request; Healthy Communities Study: How Communities Shape Children's Health (HCS) SUMMARY: Under the... control number. Proposed Collection: Title: Healthy Communities Study: How Communities Shape Children's...

  3. Clinical studies on cerebral blood flow in chronic subdural hematoma

    Fukuda, Atsuhiro; Akagi, Katsuhito; Horibe, Kunio; Yamasaki, Mami; Yuguchi, Takamichi

    1988-11-01

    Cerebral blood flow (CBF) and clinical symptoms were examined between pre- and post-operations in twenty-four patients with unilateral chronic subdural hematoma. The following results were obtained by intravenous /sup 133/Xe method : 1. There was a reducing tendency of the CBF (hemisphere) on hematoma side, in most cases. While, the groups of headache and disturbances of consciousness did not give a laterality between hematoma and opposite side without the group of hemiparesis. 2. The absolute values of the CBF in the groups of headache and disturbances of consciousness were correlated with the clinical symptoms. In the group of hemiparesis, the laterality between hematoma and opposite side was correlated with the clinical symptoms. 3. In the group of hemiparesis, the F-flow (fast-flow) had sensitive reaction more than the ISI (initial slope index) with symptomatic improvement. 4. It was found that there was not an increase in the absolute value of the CBF, which was under the normal limit between pre- and post-operations in the case without improvement. By SPECT (Method of IMP), the following results were obtained : 1. There was the area of defect at the location of hematoma and the CBF tended to reduce at the subcortical white matter and at the basal ganglia of hematoma side. 2. The CBF of the contralateral hematoma side in the hemisphere of cerebellum was also tended to reduce.

  4. Exploratory studies into seasonal flow forecasting potential for large lakes

    Sene, Kevin; Tych, Wlodek; Beven, Keith

    2018-01-01

    In seasonal flow forecasting applications, one factor which can help predictability is a significant hydrological response time between rainfall and flows. On account of storage influences, large lakes therefore provide a useful test case although, due to the spatial scales involved, there are a number of modelling challenges related to data availability and understanding the individual components in the water balance. Here some possible model structures are investigated using a range of stochastic regression and transfer function techniques with additional insights gained from simple analytical approximations. The methods were evaluated using records for two of the largest lakes in the world - Lake Malawi and Lake Victoria - with forecast skill demonstrated several months ahead using water balance models formulated in terms of net inflows. In both cases slight improvements were obtained for lead times up to 4-5 months from including climate indices in the data assimilation component. The paper concludes with a discussion of the relevance of the results to operational flow forecasting systems for other large lakes.

  5. Teachers’ work ability: a study of relationships between collective efficacy and self-efficacy beliefs

    Guidetti G

    2018-05-01

    Full Text Available Gloria Guidetti,1 Sara Viotti,1 Andreina Bruno,2 Daniela Converso1 1Department of Psychology, University of Turin, Turin, Italy; 2Department of Education Science, University of Genoa, Genoa, Italy Introduction: Work ability constitutes one of the most studied well-being indicators related to work. Past research highlighted the relationship with work-related resources and demands, and personal resources. However, no studies highlight the role of collective and self-efficacy beliefs in sustaining work ability. Purpose: The purpose of this study was to examine whether and by which mechanism work ability is linked with individual and collective efficacies in a sample of primary and middle school teachers. Materials and methods: Using a dataset consisting of 415 primary and middle school Italian teachers, the analysis tested for the mediating role of self-efficacy between collective efficacy and work ability. Results: Mediational analysis highlights that teachers’ self-efficacy totally mediates the relationship between collective efficacy and perceived work ability. Conclusion: Results of this study enhance the theoretical knowledge and empirical evidence regarding the link between teachers’ collective efficacy and self-efficacy, giving further emphasis to the concept of collective efficacy in school contexts. Moreover, the results contribute to the study of well-being in the teaching profession, highlighting a process that sustains and promotes levels of work ability through both collective and personal resources. Keywords: collective efficacy, mediation, self-efficacy, teachers, work ability

  6. Numerical study of saturation steam/water mixture flow and flashing initial sub-cooled water flow inside throttling devices

    CERN. Geneva

    2016-01-01

    In this work, a Computational Fluid-Dynamics (CFD) approach to model this phenomenon inside throttling devices is proposed. To validate CFD results, different nozzle geometries are analyzed, comparing numerical results with experimental data. Two cases are studied: Case 1: saturation steam/water mixture flow inside 2D convergent-divergent nozzle (inlet, outlet and throat diameter of nozzle are 0.1213m, 0.0452m and 0.0191m respectively). In this benchmark, a range of total inle...

  7. A Study on the Relationship of Earnings and Cash Flows: Evidence of Finance Sector in Iran

    Mahdi Salehi

    2013-08-01

    Full Text Available The present study is investigating the quality of annual accounting earnings in banking firms that have been listed in Tehran Stock Exchange (TSE and it evaluates the most important information of accounting that is earnings and cash flows. The study also intends to investigate the relationship between earnings and cash flows regarding their relationship with the expected return of stocks and the extent of informing in the analysis of the inevitable return of stocks. The analyses of data during 6 years revealed that the earnings in comparison to the cash flows are very important as they have positive effects on the stock. Moreover, in the case of the relations of earnings and earnings changes with the expected return of stocks and the relation of cash flows and cash flow changes with the expected return of stock, it was found that there is only a meaningful relationship between earning changes and the expected return of stock in banking groups. However, there is no meaningful relationship between earning and cash flows with the expected return of stock. The result was that the informational content test didn’t support the value relation of earning and cash flows. Furthermore, the classifying of information through banking group indicated that the changes of earning was in the first rank and next were earning, the changes of cash flow and cash flows.Keywords: Earnings; Cash flows; expected return; Value relevance; Banking risks

  8. Experimental study on quantitative evaluation of slow pulsatile flow of CSF with cine MRI

    Matsuda, Masao

    1991-01-01

    The present study was designed to evaluate the slow pulsatile flow of cerebrospinal fluid (CSF) quantitatively with cine MRI in phantom experiment for the clinical application. The flow phantom was constructed from a plastic tube with a narrow channel to represent the central aqueduct. The phantom was filled with water to represent the CSF. The second tube filled with stationary water was positioned beside the flow phantom and acted as a control for no-flow signal strength. The ratio of signal intensity in regions of interest for the flow phantom and the control was measured. Not only the actual velocity curve of the flowing water through the phantom but also the temporal profile of signal intensity showed two main peaks with other small peaks in one cycle. This suggested a close relationship between signal intensity of cine MRI and flow velocity. A significant correlation between the signal intensity ratio and the velocity was obtained on cine MRI pulse sequences. Cine MRI was thus found to have the ability to give quantitative information about slow pulsatile flow. The most suitable pulse sequence was fast imaging with steady state free precession pulse sequence at the flip angle between 50 and 90 degrees. This preliminary study suggests that the slow pulsatile flow of CSF passing along the aqueduct can be visualized and measured. Thus, the sequence proposed has a potential for the investigation of normal and disturbed CSF circulation and the mapping of the flow pattern in different pathological conditions. (N.K.)

  9. A Review of Some Recent Studies on Buoyancy Driven Flows in an Urban Environment

    Bodhisatta Hajra

    2014-01-01

    This paper reviews some recent studies (after 2000) pertaining to buoyancy driven flows in nature and thier use in reducing air pollution levels in a city (city ventilation). Natural convection flows occur due to the heating and cooling of various urban surfaces (e.g., mountain slopes), leading to upslope and downslope flows. Such flows can have a significant effect on city ventilation which has been the subject of study in the recent times due to increased pollution levels in a city. A major...

  10. Blood flow measurement of transverse sinuses by using MR: a phantom study of its influence factors

    Gao Gejun; Feng Xiaoyuan; Li Yuan; Geng Daoying; Yao Zhengyu

    2003-01-01

    Objective: (1) To determine the relationship between the MR signal intensity and the actual flow velocity under steady flow condition. (2) to analyze the influence produced by the angle (θ) between the flow direction and the velocity-encoded gradient direction, and flip angle as well as section thickness on the velocity measurement under oblique flow condition. (3) to develop a suitable protocol for using this method to measure volumetric flow rate in the transverse sinus system. Methods: Flow phantom, which simulated blood-flow conditions in the transverse sinus system, consisted of a fluid-filled cylinder and a bent tube with a 3.4 mm internal diameter. A 1.5 T superconductive MR imager and VIGRE sequence were used for these studies. A suitable protocol was based on consideration of the effects of (1) the accuracy of velocity and transverse area measurement of flow, and (2) signal-to-noise ratio (SNR). Results: (1) Signal intensity (y) determined by MR and the actual flow velocity (x) showed straight-line correlation, y=68.914x + 357.206, R 2 =0.998. (2) As the angle (θ) increased, the transverse area of the signal determined by MR also increased, but the value of flow velocity decreased. (3) As the flip angle increased, the SNR varied from 5.7 to 11.2. The maximum SNR was obtained with 30 degree flip angle. (4) As the section thickness increased, the SNR and the transverse area of the signal determined by MR slightly increased. Conclusions: Phase-contrast MR imaging is a practical method for measuring volumetric flow rates. The angle (θ influenced the accuracy of flow velocity and the measurement of transverse area of flow whereas the flip angle and the section thickness substantially influenced the signal-to-noise ratio and the transverse area of flow

  11. Experimental-numerical study of heat flow in deep low-enthalpy geothermal conditions

    Saeid, S.; Al-Khoury, R.; Nick, H.M.; Barends, F.

    2014-01-01

    This paper presents an intensive experimental-numerical study of heat flow in a saturated porous domain. A temperature and a flow rate range compared to that existing in a typical deep low-enthalpy hydrothermal system is studied. Two main issues are examined: the effect of fluid density and

  12. Experimental study of fuel bundle vibrations with rods subjected to mixed axial flow and cross-flow provided by a narrow gap (baffle jetting interaction)

    Boulanger, P.; Jacques, Y.; Fardeau, P.; Barbier, D.; Rigaudeau, J.

    1997-01-01

    The Hydraulic Core Laboratory (LHC) performs experimental studies of PWR fuel assembly mechanical behaviour submitted to representative flows in PWR core. Cross-flows prove particularly troublesome by generating on rods, in special cases, vibratory levels high enough to induce early grid to rod fretting. The fluid-structure interaction under mixed axial and cross-flow is also a major topic for analysis. The authors present a test loop devoted to the mixed axial-cross-flow fluid-structure interaction on representative half-scale mockup which is able to simulate, under ambient conditions, any complex flow (direction and flow rates) representative of PWR core flows. Despite its reduced size, the mockup retains the overall structure of a PWR fuel assembly. Rods displacement/velocity and velocity flow field are measured by laser techniques

  13. Accuracy of a self-collection kit for the microbiological study of the vaginal content

    Mauro Romero L. Passos

    Full Text Available Diagnosis of vaginal discharge is frequently performed in an empirical way, leading to inadequate treatment. This study tested the accuracy of a self-collection kit for microbiological study of the vaginal content. One hundred and forty-two women of Family Health Program units in Niterói and Piraí cities were enrolled in order to have their vaginal content studied. A brief explanation and a self-collection kit were provided in order to sample the vaginal content. The self-collection kit was composed of one empty plastic tube, two glass slides, a long handle cytobrush, an identification card and guideline notes. The vaginal sample was applied on the glass slides by the women and stained by Gram technique. A second sampling was done by the medical personnel. The microbiological diagnosis in a blinded analysis was made under optical microscopy. A validation diagnosis test was done taking the medical collection results as a gold standard. A total of 106 women had followed the protocol and were included in the study. Microbiological analysis was unsatisfactory in 12 cases (6 cases of self-collection material and 6 cases of medical collection. The microbiological analyses in the self-collection and in the medical collection material were respectively: bacterial vaginosis in 21.7% and 17.9%, non bacillar flora in 10.3% and 11.3%, vaginal trichomoniasis in 5.66% and 5.6%, candidiasis in 3.78% and 2.8% and a normal microbiota in 52.8% and 56.6%. The Kappa coefficient suggested a "very good correlation" of the microbiological results between the two methods of collection (K=0.7945. The self-collection kit provides samples for microbiological analysis of the vaginal microbiota as good as medical collection.

  14. Experimental Study on Flow Boiling of Carbon Dioxide in a Horizontal Microfin Tube

    Kuwahara, Ken; Ikeda, Soshi; Koyama, Shigeru

    This paper deals with the experimental study on flow boiling heat transfer of carbon dioxide in a micro-fin tube. The geometrical parameters of micro-fin tube used in this study are 6.07 mm in outer diameter, 5.24 mm in average inner diameter, 0.256 mm in fin height, 20.4 in helix angle, 52 in number of grooves and 2.35 in area expansion ratio. Flow patterns and heat transfer coefficients were measured at 3-5 MPa in pressure, 300-540 kg/(m2s) in mass velocity and -5 to 15 °C in CO2 temperature. Flow patterns of wavy flow, slug flow and annular flow were observed. The measured heat transfer coefficients of micro-fin tube were 10-40 kW/(m2K). Heat transfer coefficients were strongly influenced by pressure.

  15. Determination of Flow Resistance Coefficient for Vegetation in Open Channel: Laboratory study

    Aliza Ahmad, Noor; Ali, ZarinaMd; Arish, Nur Aini Mohd; Munirah Mat Daud, Azra; Fatin Amirah Alias, Nur

    2018-04-01

    This study focused on determination of flow resistances coefficient for grass in an open channel. Laboratory works were conducted to examine the effects of varying of roughness elements on the flume to determine flow resistance coefficient and also to determine the optimum flow resistance with five different flow rate, Q. Laboratory study with two type of vegetation which are Cow Grass and Pearl Grass were implementing to the bed of a flume. The roughness coefficient, n value is determine using Manning’s equation while Soil Conservation Services (SCS) method was used to determine the surface resistance. From the experiment, the flow resistance coefficient for Cow Grass in range 0.0008 - 0.0039 while Pearl Grass value for the flow resistance coefficient are in between 0.0013 - 0.0054. As a conclusion the vegetation roughness value in open channel are depends on density, distribution type of vegetation used and physical characteristic of the vegetation itself

  16. A study on effects of cash flow patterns and auditors’ opinions in predicting financial distress

    Fatemeh Namvar

    2013-07-01

    Full Text Available Bankruptcy has been one of the most important issues among investors in stock market and there are literally different techniques for predicting bankruptcy. In this paper, we study on effects of cash flow patterns and auditors’ opinions in predicting financial distress on some 80 selected firms traded on Tehran Stock Exchange over the period 2005-2011. In this study, the combination of cash flow patterns represent firm’s resource allocations and operational capabilities interacted with their strategy choices. In additions, predictions about each individual cash flow components, operational, investment, financial, are derived from economic theory, which forms a basis for the life proxy. We use cash flow patterns in the decline stage and compare the results with auditors’ opinions. The results indicate that cash flow patterns could predict financial distress companies in Iran. In addition, the effective cash flow patterns in predicting financial distress is more than auditors’ feedbacks.

  17. A study on the flow induced vibration in two phase flow under heating and non-heating conditions

    Kim, Dae Hun

    2007-02-01

    Critical heat flux (CHF) enhancement devices, like a spacer grid with mixing vane, cause flow-induced vibration (FIV) due to turbulence made by structural resistance. CHF enhancement and FIV reduction are usually studied separately. The main purpose of this article is to investigate the relationship between CHF and FIV. Information of flow-induced vibration due to wire coil design, is experimentally presented in this study by detecting flow-induced vibration under the two-phase flow condition with wire coil inserts. CHF experiments were performed in an upward vertical annulus tube under controlled vibration conditions to determine the effect of vibration on CHF. FIV was measured in an upward vertical tube with various wire coil inserts using air-water as flow material. CHF experiments were performed at one atmosphere with mechanically controlled vibration. A quartz tube (inner diameter of 17 mm, thickness of 2mm and length of 0.72 m) was used for outer tube and a SUS-304 tube (outer diameter of 6.35 mm, thickness of 0.89 mm and length of 0.7 m) was used for the inner heater. Vibration of the heater tube with an amplitude range of 0.1 mm to 0.5 mm and a frequency range of 10 Hz to 50 Hz was carried out at a mass flux of 115 kg/m 2 s and 215 kg/m 2 s. CHF was enhanced by vibration with a maximum ratio of 16.4 %. CHF was increased with increased amplitude and quality. The CHF correlation was developed with R (coefficient of correlation) of 0.903. FIV measuring experiments were performed at one atmosphere by changing the inserted wire coil type. An acrylic tube was used for the test section with inner diameter of 25 mm, thickness of 10 mm and length of 0.5 m. Four types of wire coil, which have a thickness of between 2 mm and 3 mm and pitch length of between 25 mm and 50 mm, were used. FIV and dynamic pressure were detected in water mass flux range of 100 ∼ 3060 kg/m 2 s and air mass flux range of 5.02 ∼ 60.3 kg/m 2 s. Vibration increased along with mass flux and

  18. Study on flow characteristics of chemically reacting liquid jet

    Hong Seon Dae; Okamoto, Koji; Takata, Takashi; Yamaguchi, Akira

    2004-07-01

    Tube rupture accidents in steam generators of sodium-cooled fast breeder reactors are important for safety because the rupture may propagates to neighboring tubes due to sodium-water reaction. In order to clarify the thermal-hydraulic phenomena in the accidents, the flow pattern and the interface in multi-phase flow must be investigated. The JNC cooperative research scheme on the nuclear fuel cycle with the University of Tokyo has been carried to develop a simultaneous measurement system of concentration and velocity profiles and to evaluate influence of chemical reaction on mixing phenomena. In the experiments, aqueous liquor of acetic acid and ammonium hydroxide are selected as a simulant fluid instead of liquid sodium and water vapor. The following conclusions are obtained in this research. Laser Induced Fluorescence (LIF) technique was adopted to measure reacting zone and pH distribution in chemically reacting liquid round free jet. As a result, it was found that the chemical reaction, which took place at the interface between the jet and outer flow, suppressed the mixing phenomenon (in 2001 research). Dynamic Particle Image Velocimetry (PIV) method was developed to measure instantaneous velocity profile with high temporal resolution. In the Dynamic PIV, a high-speed video camera coupled with a high-speed laser pulse generator was implemented. A time-line trend of interfacial area in the free jet was investigated with the Dynamic PIV. This technique was also applied to a complicated geometry (in 2002 research). A new algorithms for image analysis was developed to evaluated the Dynamic PIV data in detail. The characteristics of the mixing phenomenon with reacting jet such as the turbulent kinetic energy and the Reynolds stress were estimated in a spatial and temporal spectrum (in 2003 research). (author)

  19. Experimental and Computational Study of Multiphase Flow Hydrodynamics in 2D Trickle Bed Reactors

    Nadeem, H.; Ben Salem, I.; Kurnia, J. C.; Rabbani, S.; Shamim, T.; Sassi, M.

    2014-12-01

    Trickle bed reactors are largely used in the refining processes. Co-current heavy oil and hydrogen gas flow downward on catalytic particle bed. Fine particles in the heavy oil and/or soot formed by the exothermic catalytic reactions deposit on the bed and clog the flow channels. This work is funded by the refining company of Abu Dhabi and aims at mitigating pressure buildup due to fine deposition in the TBR. In this work, we focus on meso-scale experimental and computational investigations of the interplay between flow regimes and the various parameters that affect them. A 2D experimental apparatus has been built to investigate the flow regimes with an average pore diameter close to the values encountered in trickle beds. A parametric study is done for the development of flow regimes and the transition between them when the geometry and arrangement of the particles within the porous medium are varied. Liquid and gas flow velocities have also been varied to capture the different flow regimes. Real time images of the multiphase flow are captured using a high speed camera, which were then used to characterize the transition between the different flow regimes. A diffused light source was used behind the 2D Trickle Bed Reactor to enhance visualizations. Experimental data shows very good agreement with the published literature. The computational study focuses on the hydrodynamics of multiphase flow and to identify the flow regime developed inside TBRs using the ANSYS Fluent Software package. Multiphase flow inside TBRs is investigated using the "discrete particle" approach together with Volume of Fluid (VoF) multiphase flow modeling. The effect of the bed particle diameter, spacing, and arrangement are presented that may be used to provide guidelines for designing trickle bed reactors.

  20. Oscillatory squeeze flow for the study of linear viscoelastic behavior

    Wingstrand, Sara Lindeblad; Alvarez, Nicolas J.; Hassager, Ole

    2016-01-01

    of molten polymers and suspensions. The principal advantage of squeeze flow rheometer over rotational devices is the simplicity of the apparatus. It has no air bearing and is much less expensive and easier to use. Accuracy may be somewhat reduced, but for quality control purposes, it could be quite useful....... It might also find application as the central component of a high-throughput rheometer for evaluating experimental materials. The deformation is not simple shear, but equations have been derived to show that the oscillatory compressive (normal) force that is measured can serve as a basis for calculating...

  1. Local studies in horizontal gas-liquid slug flow

    Sharma, S.; Lewis, S.; Kojasoy, G.

    1998-01-01

    The local axial velocity profile development in a horizontal air-water slug flow-pattern was experimentally investigated by simultaneously using two hot-film anemometers. One of the probes was exclusively used as phase identifier while the other probe was traversed for local velocity measurements. It was shown that the velocity rapidly develops into asymmetric but nearly fully-developed profiles within the liquid slugs whereas the velocity never develops into quasi-fully-developed profiles within the liquid layer underneath passing gas slugs. Transient nature of velocity at a given location was demonstrated. (author)

  2. Numerical study of interfacial flows with immersed solids

    Kim, Sung Il; Son, Gi Hun

    2003-01-01

    A numerical method is presented for computing unsteady incompressible two-phase flows with immersed solids. The method is based on a level set technique for capturing the phase interface, which is modified to satisfy a contact angle condition at the solid-fluid interface as well as to achieve mass conservation during the whole calculation procedure. The modified level set method is applied for numerical simulation of bubble deformation in a micro channel with a cylindrical solid block and liquid jet from a micro nozzle

  3. A numerical study of blood flow using mixture theory

    Wu, Wei-Tao; Aubry, Nadine; Massoudi, Mehrdad; Kim, Jeongho; Antaki, James F.

    2014-01-01

    In this paper, we consider the two dimensional flow of blood in a rectangular microfluidic channel. We use Mixture Theory to treat this problem as a two-component system: One component is the red blood cells (RBCs) modeled as a generalized Reiner–Rivlin type fluid, which considers the effects of volume fraction (hematocrit) and influence of shear rate upon viscosity. The other component, plasma, is assumed to behave as a linear viscous fluid. A CFD solver based on OpenFOAM® was developed and ...

  4. Flow Structures and Efficiency of Swimming Fish school: Numerical Study

    Yatagai, Yuzuru; Hattori, Yuji

    2013-11-01

    The flow structure and energy-saving mechanism in fish school is numerically investigated by using the volume penalization method. We calculate the various patterns of configuration of fishes and investigate the relation between spatial arrangement and the performance of fish. It is found that the down-stream fish gains a hydrodynamic advantage from the upstream wake shed by the upstream fish. The most efficient configuration is that the downstream fish is placed in the wake. It reduces the drag force of the downstream fish in comparison with that in solo swimming.

  5. Convection Study by PIV Method Within Horizontal Liquid Layer Evaporating Into Inert Gas Flow

    Kreta Aleksei

    2016-01-01

    Full Text Available The paper is devoted to the experimental study of convection in a horizontal evaporating liquid layer (ethanol of limited size under the action of gas flow (air. The two-dimensional velocity field in the liquid layer is obtained using the PIV method. The existence of a vortex convective flow within a liquid layer directed towards the gas flow has been revealed.

  6. A Dual-Plane PIV Study of Turbulent Heat Transfer Flows

    Wernet, Mark P.; Wroblewski, Adam C.; Locke, Randy J.

    2016-01-01

    Thin film cooling is a widely used technique in turbomachinery and rocket propulsion applications, where cool injection air protects a surface from hot combustion gases. The injected air typically has a different velocity and temperature from the free stream combustion flow, yielding a flow field with high turbulence and large temperature differences. These thin film cooling flows provide a good test case for evaluating computational model prediction capabilities. The goal of this work is to provide a database of flow field measurements for validating computational flow prediction models applied to turbulent heat transfer flows. In this work we describe the application of a Dual-Plane Particle Image Velocimetry (PIV) technique in a thin film cooling wind tunnel facility where the injection air stream velocity and temperatures are varied in order to provide benchmark turbulent heat transfer flow field measurements. The Dual-Plane PIV data collected include all three components of velocity and all three components of vorticity, spanning the width of the tunnel at multiple axial measurement planes.

  7. Effects of mouthwash interventions on xerostomia and unstimulated whole saliva flow rate among hemodialysis patients: A randomized controlled study.

    Yu, I-Chen; Tsai, Yun-Fang; Fang, Ji-Tseng; Yeh, Mei-Ming; Fang, Jia-You; Liu, Chieh-Yu

    2016-11-01

    Dry mouth (xerostomia) is a common symptom in hemodialysis patients, which is associated with a reduced salivary flow. Xerostomia affects patients' oral health and quality of life. The aim of this study was to investigate using a mouthwash as a means to reduce xerostomia and improve saliva flow rates in hemodialysis patients. A randomized controlled trial. Three dialysis centers in Northern Taiwan served as the study sites. Patients were purposively sampled from three hemodialysis centers in Taiwan and randomly assigned to one of three groups: pure water mouthwash; n=41, licorice mouthwash; n=44, or no mouthwash (control); n=37. The Summated Xerostomia Inventory, and unstimulated whole salivary flow rate measured dry mouth and salivary flow, respectively. Data was collected at baseline, dialysis Day 5 and Day 10. One hundred twenty-two patients participated in this study. Baselines were adjusted for any imbalances in variables and generalized estimating equations analysed the data. Compared to control, a pure water mouthwash resulted in an increase in the unstimulated salivary flow rate of 25.85×10 -3 mL/min and 25.78×10 -3 mL/min (pXerostomia Inventory scores. The licorice mouthwash also significantly improved the unstimulated salivary flow rates to 114.92×10 -3 mL/min, and 131.61×10 -3 mL/min at Day 5 and Day 10, respectively (pXerostomia Inventory (pxerostomia. This suggests the use of a licorice mouthwash may effectively relieve feelings of dry mouth in hemodialysis patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Experimental Study of gas-liquid two-phase flow affected by wall surface wettability

    Takamasa, T.; Hazuku, T.; Hibiki, T.

    2008-01-01

    To evaluate the effect of wall surface wettability on the characteristics of upward gas-liquid two-phase flow in a vertical pipe, an experimental study was performed using three test pipes: an acrylic pipe, a hydrophilic pipe and a hydrophobic pipe. Basic flow characteristics such as flow patterns, pressure drop and void fraction were measured in these three pipes. In the hydrophilic pipe, a slug to churn flow transition boundary was shifted to a higher gas velocity at a given liquid velocity, whereas a churn to annular flow transition boundary was shifted to a lower gas velocity at a given liquid velocity. In the hydrophobic pipe, an inverted-churn flow regime was observed in the region where the churn flow regime was observed in the acrylic pipe, while a droplet flow regime was observed in the region where an annular flow regime was observed in the acrylic pipe. At a high gas flow rate, the mean void fraction in the hydrophobic pipe was higher than in the acrylic pipe. The effect of surface wettability on frictional pressure loss was confirmed to be insignificant under the present experimental conditions

  9. Experimental study of fluid flow in the entrance of a sinusoidal channel

    Oviedo-Tolentino, F.; Romero-Mendez, R.; Hernandez-Guerrero, A.; Giron-Palomares, B.

    2008-01-01

    An experimental flow visualization study of the entrance section of channels formed with sinusoidal plates was made. The experiments were conducted in a water tunnel and a laser illuminated particle tracking was used as the technique of flow visualization. The geometric parameters of the plates were maintained constant while the distance between plates, phase angle, and the Reynolds number were varied during the experiments. The flow regimes that were found in the experiments are steady, unsteady and significantly-mixed flows. Instabilities of the flow first appear near the exit of the channel, and move closer to the inlet waves as the Reynolds number grows, but in the first wave from inlet the flow is always steady. The results show that, for all other parameters fixed, the Reynolds number at which unsteady flow first appears grows with the distance between plates. The phase angle that best promotes unsteady flow depends on the average distance between plates: for certain average distance between plates, there is a phase angle that best disturbs the flow. For the set of parameters used in this experiment, a channel with eight waves is sufficiently long and the flow features presented in the first eight waves of a longer channel will be similar to what was observed here

  10. Optical measurement of blood flow in exercising skeletal muscle: a pilot study

    Wang, Detian; Baker, Wesley B.; Parthasarathy, Ashwin B.; Zhu, Liguo; Li, Zeren; Yodh, Arjun G.

    2017-07-01

    Blood flow monitoring during rhythm exercising is very important for sports medicine and muscle dieases. Diffuse correlation spectroscopy(DCS) is a relative new invasive way to monitor blood flow but suffering from muscle fiber motion. In this study we focus on how to remove exercise driven artifacts and obtain accurate estimates of the increase in blood flow from exercise. Using a novel fast software correlator, we measured blood flow in forearm flexor muscles of N=2 healthy adults during handgrip exercise, at a sampling rate of 20 Hz. Combining the blood flow and acceleration data, we resolved the motion artifact in the DCS signal induced by muscle fiber motion, and isolated the blood flow component of the signal from the motion artifact. The results show that muscle fiber motion strongly affects the DCS signal, and if not accounted for, will result in an overestimate of blood flow more than 1000%. Our measurements indicate rapid dilation of arterioles following exercise onset, which enabled blood flow to increase to a plateau of 200% in 10s. The blood flow also rapidly recovered to baseline following exercise in 10s. Finally, preliminary results on the dependence of blood flow from exercise intensity changes will be discussed.

  11. Application of two-phase flow for cooling of hybrid microchannel PV cells: A comparative study

    Valeh-e-Sheyda, Peyvand; Rahimi, Masoud; Karimi, Ebrahim; Asadi, Masomeh

    2013-01-01

    Highlights: ► Showing cooling potential of gas–liquid two-phase flow in microchannels for PV cell. ► Introducing the concept of using slug flow in microchannels for cooling of PV cells. ► In single-phase flow, increasing the liquid flow rate enhances the PV power. ► Showing that in two-phase flow the output power related the fluid flow regime. ► By coupling PV and microchannel an increase up to 38% in output power was observed. - Abstract: This paper reports the experimental data from performance of two-phase flows in a small hybrid microchannel solar cell. Using air and water as two-phase fluid, the experiments were conducted at indoor condition in an array of rectangular microchannels with a hydraulic diameter of 0.667 mm. The gas superficial velocity ranges were between 0 and 3.27 m s −1 while liquid flow rate was 0.04 m s −1 . The performance analysis of the PV cell at slug and transitional slug/annular flow regimes are the focus of this study. The influence of two-phase working fluid on PV cell cooling was compared with single-phase. In addition, the great potential of slug flow for heat removal enhancement in PV/T panel was investigated. The obtained data showed the proposed hybrid system could substantially increases the output power of PV solar cells

  12. A study of swirl flow in draft tubes

    Dahlhaug, Ole Gunnar

    1997-12-31

    This thesis presents measurements performed inside conical diffuser and bend, draft tubes of model hydro turbines, and draft tube of a prototype hydro turbine. Experimental results for swirling flow in conical diffuser and bend are presented in three different geometries. The axial velocity decreases at the centre of the tube at high swirl numbers because of an axial pressure gradient set up by the downstream frictional damping of the tangential velocities and the pressure increase downstream of the diffuser. Analytical models of the tangential velocity profiles are found and the radial pressure distribution calculated. Good correlation to the measured pressure distribution was achieved. Diffuser efficiency was calculated based on the equations for velocity and pressure profiles, which gave a qualified estimate of the diffuser hydraulic performance. The calculation shows that the bend reduces the efficiency by more than 30%. For a straight tube followed by a diffuser, numerical calculations were done, using K{epsilon}, RNG and RSM turbulence models for all measured swirl numbers. The K{epsilon} model gave best results for the forced vortex profile at low swirl numbers, while the RSM model gave best results at high swirl number. The turbulent kinetic energy at high swirl numbers gave the largest difference between the calculated and the measured values. Measurements on draft tubes in model turbines show the importance of good draft tube design. Prototype measurements on a Francis turbine show how the outlet draft tube flow should be measured for prototype draft tube evaluation. 54 refs., 118 figs., 2 tabs.

  13. A study of swirl flow in draft tubes

    Dahlhaug, Ole Gunnar

    1998-12-31

    This thesis presents measurements performed inside conical diffuser and bend, draft tubes of model hydro turbines, and draft tube of a prototype hydro turbine. Experimental results for swirling flow in conical diffuser and bend are presented in three different geometries. The axial velocity decreases at the centre of the tube at high swirl numbers because of an axial pressure gradient set up by the downstream frictional damping of the tangential velocities and the pressure increase downstream of the diffuser. Analytical models of the tangential velocity profiles are found and the radial pressure distribution calculated. Good correlation to the measured pressure distribution was achieved. Diffuser efficiency was calculated based on the equations for velocity and pressure profiles, which gave a qualified estimate of the diffuser hydraulic performance. The calculation shows that the bend reduces the efficiency by more than 30%. For a straight tube followed by a diffuser, numerical calculations were done, using K{epsilon}, RNG and RSM turbulence models for all measured swirl numbers. The K{epsilon} model gave best results for the forced vortex profile at low swirl numbers, while the RSM model gave best results at high swirl number. The turbulent kinetic energy at high swirl numbers gave the largest difference between the calculated and the measured values. Measurements on draft tubes in model turbines show the importance of good draft tube design. Prototype measurements on a Francis turbine show how the outlet draft tube flow should be measured for prototype draft tube evaluation. 54 refs., 118 figs., 2 tabs.

  14. Flow loop studies with AMAX coal-water mixtures

    Wildman, D.J.; Ekmann, J.M.

    1984-03-01

    The coal-water mixtures (CWM) with a stabilizer and the CWM without stabilizers were successfully transported through a flow loop facility under a variety of conditions. The handling characteristics of both CWM were reasonable. The mix tank mixer was not needed during nontesting hours to prevent settling of either material. After several days of transporting the nonstabilized material in the loop facility, the viscosity-reducing agent became ineffective. It was necessary to increase the concentration of the viscosity-reducing agent. The material with stabilizer could not be transported through the loop facility at mass flow rates greater than 209 lb/min until overnight shearing of the CWM in the tank. The CWM without a stabilizer appeared to be slightly shear-thickening, whereas the stabilized CWM initially exhibited shear-thinning behavior. The pressure losses measured for the nonstabilized material were similar to the pressure losses measured for CWM prepared at PETC with three or four percent higher concentration of Pittsburgh seam coal. Tests performed with the stabilized CWM experienced pressure losses similar to CWM prepared at PETC with Pittsburgh seam coal of five to seven percent higher concentration. Tests 1A, 2A, 1B, and 2B were not included in the comparison of in-house-prepared CWM due to differences in pretest handling procedures. 1 figure, 2 tables.

  15. Laboratory studies of fluid flow through borehole seals

    South, D.L.

    1983-01-01

    Boreholes in the vicinity of a nuclear waste repository must be reliably sealed to prevent rapid migration of radionuclide contaminated water from the vicinity of the repository to the accessible environment. Few data currently exist regarding the effectiveness of borehole sealing. The objective of this research was to assess the performance of borehole seals under laboratory conditions, particularly with regard to varying stress fields. The approach used to evaluate borehole seals was to compare flow through a sealed borehole with flow through intact rock. Granite, basalt, and tuff were tested, using either cement or bentonite as the seal material. The main conclusions reached as a result of the experiments is that currently existing materials are capable of forming high quality seals when placed under laboratory conditions. Variation of triaxial stress state about a borehole does not significantly affect seal performance if the rock is stiffer than the seal material. Temperature/moisture variations (drying) degraded the quality of cement seals significantly. Performance partially recovered upon resaturation. Significant remaining questions include field emplacement techniques; field vertification of plug quality; plug performance over long time periods, particularly with respect to temperature/moisture variations and chemical stability; and radionuclide sorption capabilities. Scale effects are also important, as shafts and drifts must be sealed as well as larger diameter boreholes

  16. Numerical study of unsteady viscous flow past oscillating airfoil

    Jin Yan; Yuan Xin [Tsinghua Univ., Dept. of Thermal Engineering, Beijing (China)

    2001-07-01

    Accurate simulation of the dynamic stall of an oscillating airfoil is of major importance to wing and wind turbine blade design. However, dynamic stall is complicated and influenced by many factors, such as geometry shape of the airfoil, reduced frequency, etc. The difficulties of simulation are both mathematical (numerical method) and physical (turbulence model). The present paper has introduced a new numerical method (new LU-type scheme and fourth-order higher resolution MUSCL TVD scheme) and q-{omega} turbulence modelling to calculate the unsteady flowfields of an oscillating NACA0015 airfoil. The test targets include attached flow, light-stall and deep-stall of the airfoil. The calculated results for attached flow and light-stall are in good agreement with those of experiments. The calculated results for deep-stall also show improvement, especially during the downstroke of the oscillation. However, there is still a significant difference between the results of calculation and experiment in the hysteresis curves of the drag coefficient. One reason is that the q-{omega} turbulence model still has limitations. Another is that the drag coefficient is difficult to measure and the experiments are not reliable. (Author)

  17. Challenges and solutions for studying collective animal behaviour in the wild.

    Hughey, Lacey F; Hein, Andrew M; Strandburg-Peshkin, Ariana; Jensen, Frants H

    2018-05-19

    Mobile animal groups provide some of the most compelling examples of self-organization in the natural world. While field observations of songbird flocks wheeling in the sky or anchovy schools fleeing from predators have inspired considerable interest in the mechanics of collective motion, the challenge of simultaneously monitoring multiple animals in the field has historically limited our capacity to study collective behaviour of wild animal groups with precision. However, recent technological advancements now present exciting opportunities to overcome many of these limitations. Here we review existing methods used to collect data on the movements and interactions of multiple animals in a natural setting. We then survey emerging technologies that are poised to revolutionize the study of collective animal behaviour by extending the spatial and temporal scales of inquiry, increasing data volume and quality, and expediting the post-processing of raw data.This article is part of the theme issue 'Collective movement ecology'. © 2018 The Author(s).

  18. Experimental Study of Unsteady Flow Separation in a Laminar Boundary Layer

    Bonacci, Andrew; Lang, Amy; Wahidi, Redha; Santos, Leonardo

    2017-11-01

    Flow separation, caused by an adverse pressure gradient, is a major problem in many applications. Reversing flow near the wall is the first sign of incipient separation and can bristle shark scales which may be linked to a passive, flow actuated separation control mechanism. An investigation of how this backflow forms and how it interacts with shark skin is of interest due to the fact that this could be used as a bioinspired means of initiating flow control. A water tunnel experiment aims to study unsteady separation with a focus on the reversing flow development near the wall within a flat plate laminar boundary layer (Re on order of 105) as an increasing adverse pressure gradient is induced by a rotating cylinder. Unsteady reversing flow development is documented using DPIV. Funding was provided by the National Science Foundation under the Research Experience for Undergraduates (REU) program (EEC 1659710) and the Army Research Office.

  19. Study of operational parameters on the performance of micro PEMFCs with different flow fields

    Hsieh, S.-S.; Yang, S.-H.; Kuo, J.-K.; Huang, C.-F.; Tsai, H.-H.

    2006-01-01

    The effects of different operating parameters on micro PEMFC performances were experimentally studied for three different flow field configurations (interdigitated, mesh, and serpentine). Experiments with different cell operating temperatures and different backpressures on the H 2 flow channels, as well as various combinations of these parameters, have been conducted for three different flow geometries. The micro PEMFCs were designed and fabricated inhouse through a deep UV lithography technique and the SU-8 photoresist was used as microstructure material for the fuel cell flow field plates. Results are presented in the form of polarization VI curves and PI curves under different operating conditions. The possible transport mechanisms associated with the parametric effects were discussed. In addition, it was found that among the three flow patterns considered, significant improvements can be reached with a specified flow geometry

  20. Study for discharge coefficient of flow nozzles. Prediction by using numerical simulation

    Ikeda, Hiroshi; Sakai, Norio; Yamamoto, Yasushi; Arai, Kenji; Matsumoto, Masaaki

    2008-01-01

    In nuclear plant, as water feeding into reactor have much effect on thermal power of plant, it is important to measure accurately the flow rate of water. Flow nozzle is on of typical differential pressure type flow meters and the discharge coefficient is used to calculate the flow rate. This coefficient is given by actual experiment and theory. We studied the theoretical assumption of the discharge coefficient curve using numerical simulation and evaluated the effect of flow nozzle configuration on the coefficient numerically and experimentally. As the result, numerical simulation can predict the discharge coefficient of theoretical curve within 0.3%. And we found that the throat length and throat tapping location of flow nozzle have much effect on the coefficient. (author)