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Sample records for eddy rubin highlights

  1. Martin Rubin: Thrillers

    OpenAIRE

    Morsch, Thomas

    2000-01-01

    This book is the first in a new series from Cambridge University Press entitled Genres in American Cinema (general editor : Barry Keith Grant). The thriller has been a much-neglected genre in film studies (less so in literature), so any new work in this field is to be welcomed. Martin Rubin has successfully fulfilled the series'aim of providing « a comprehensive account of its genre... balancing theoretical and historical discussion with close readings of representative films » (p. iii). Yet ...

  2. Campbell's and Rubin's Perspectives on Causal Inference

    Science.gov (United States)

    West, Stephen G.; Thoemmes, Felix

    2010-01-01

    Donald Campbell's approach to causal inference (D. T. Campbell, 1957; W. R. Shadish, T. D. Cook, & D. T. Campbell, 2002) is widely used in psychology and education, whereas Donald Rubin's causal model (P. W. Holland, 1986; D. B. Rubin, 1974, 2005) is widely used in economics, statistics, medicine, and public health. Campbell's approach focuses on…

  3. Sobolev type spaces associated with the q-Rubin's operator

    Directory of Open Access Journals (Sweden)

    Neji Bettaibi

    2014-05-01

    Full Text Available In this paper we introduce and   study   some $q$-Sobolev type spaces by using the harmonic analysis associated with the q-Rubin operator. In particular, embedding theorems for these spaces are established.  Next, we introduce the q-Rubin potential spaces and study some of its properties.

  4. Selection bias and the Rubin-Ford effect

    International Nuclear Information System (INIS)

    James, P.A.; Joseph, R.D.; Collins, C.A.

    1991-01-01

    We have re-examined the 'Rubin-Ford effect', and more recent claims of galaxy streaming from the same galaxy sample, to investigate the impact of selection effects on these results. A 'Monte Carlo'-type analysis was applied to simulate the selection procedure used to obtain this sample, and a strong bias was identified, resulting in apparent velocity flows at 600-800 km s -1 . Thus the 'Rubin-Ford effect' and the associated galaxy streaming are spurious effects resulting from the method of sample selection. (author)

  5. Rubin's CMS reduction method for general state-space models

    NARCIS (Netherlands)

    Kraker, de A.; Campen, van D.H.

    1996-01-01

    In this paper the Rubin CMS procedure for the reduction and successive coupling of undamped structural subsystems with symmetric system matrices will be modified for the case of general damping. The final coordinate transformation is based on the use of complex (residual) flexibility modes,

  6. Isotropic cosmic expansion and the Rubin-Ford effect

    International Nuclear Information System (INIS)

    Fall, S.M.; Jones, B.J.T.

    1976-01-01

    It is shown that the Rubin-Ford data (Astrophys. J. Lett. 183:L111 (1973)), often taken as evidence for large scale anisotropic cosmic expansion, probably only reflect the inhomogeneous distribution of galaxies in the region of the sample. The data presented are consistent with isotropic expansion, an unperturbed galaxy velocity field, and hence a low density Universe. (author)

  7. Significant characteristics of the new maize hybrid Rubin-7

    Directory of Open Access Journals (Sweden)

    Jeličić Zora

    2003-01-01

    Full Text Available The Rubin-7 maize hybrid belongs to the FAO 700 maturity group. It is characterized by high yield potential for kernels, which was proven during investigations by the Committee for Species. During the three year monitoring period, from 1999 to 2001, the average yield of kernel was 9.412 t/ha which is 5% above the ZP 704 standard, and was highly statistically significant. Resistance to disease was high for Ustilago maydis 0.49, Fusarium spp. 0.13, and Exerohilum turcicum 1.25. Tolerance against Ostrinia nubilalis is 3-33. All of the above parameters and the agreeable phenotype of this hybrid indicate the value of Rubin-7. .

  8. Building genetic tools in Drosophila research: an interview with Gerald Rubin

    Directory of Open Access Journals (Sweden)

    2016-04-01

    Full Text Available Gerald (Gerry Rubin, pioneer in Drosophila genetics, is Founding Director of the HHMI-funded Janelia Research Campus. In this interview, Gerry recounts key events and collaborations that have shaped his unique approach to scientific exploration, decision-making, management and mentorship – an approach that forms the cornerstone of the model adopted at Janelia to tackle problems in interdisciplinary biomedical research. Gerry describes his remarkable journey from newcomer to internationally renowned leader in the fly field, highlighting his contributions to the tools and resources that have helped establish Drosophila as an important model in translational research. Describing himself as a ‘tool builder’, his current focus is on developing approaches for in-depth study of the fly nervous system, in order to understand key principles in neurobiology. Gerry was interviewed by Ross Cagan, Senior Editor of Disease Models & Mechanisms.

  9. Rubin H. Flocks and Colloidal Gold Treatments for Prostate Cancer

    Directory of Open Access Journals (Sweden)

    Henry M. Rosevear

    2011-01-01

    Full Text Available In the early 1950s, Rubin H. Flocks of the University of Iowa began to treat prostate cancer patients with colloidal gold (Au198 therapy, evolving his technique over nearly 25 years in 1515 patients. We reviewed the long-term outcomes of Flocks' prostate cancer patients as compared to those patients treated by other methods at the University of Iowa before Flocks' chairmanship. We reviewed archived patient records, Flocks' published data, and long-term survival data from the Iowa Tumor Registry to determine short- and long-term outcomes of Flocks' work with colloidal gold. We also reviewed the literature of Flocks' time to compare his outcomes against those of his contemporaries. The use of colloidal gold, either as primary or adjunctive therapy, provided short- and long-term survival benefit for the majority of Flocks' patients as compared to historical treatment options (p < 0.001. Flocks' use of colloidal gold for the treatment of locally advanced prostate cancer offered short- and long-term survival benefits compared to other contemporary treatments.

  10. Category Selectivity of Human Visual Cortex in Perception of Rubin Face–Vase Illusion

    Directory of Open Access Journals (Sweden)

    Xiaogang Wang

    2017-09-01

    Full Text Available When viewing the Rubin face–vase illusion, our conscious perception spontaneously alternates between the face and the vase; this illusion has been widely used to explore bistable perception. Previous functional magnetic resonance imaging (fMRI studies have studied the neural mechanisms underlying bistable perception through univariate and multivariate pattern analyses; however, no studies have investigated the issue of category selectivity. Here, we used fMRI to investigate the neural mechanisms underlying the Rubin face–vase illusion by introducing univariate amplitude and multivariate pattern analyses. The results from the amplitude analysis suggested that the activity in the fusiform face area was likely related to the subjective face perception. Furthermore, the pattern analysis results showed that the early visual cortex (EVC and the face-selective cortex could discriminate the activity patterns of the face and vase perceptions. However, further analysis of the activity patterns showed that only the face-selective cortex contains the face information. These findings indicated that although the EVC and face-selective cortex activities could discriminate the visual information, only the activity and activity pattern in the face-selective areas contained the category information of face perception in the Rubin face–vase illusion.

  11. AEB highlights

    International Nuclear Information System (INIS)

    1975-01-01

    AEB HIGHLIGHTS is a half-yearly report reflecting the most important recent achievements of the various Research and Technical Divisions of the Atomic Energy Board. It appears alternately in English and Afrikaans [af

  12. BBG Highlights

    Data.gov (United States)

    Broadcasting Board of Governors — BBG Highlights is a monthly summary of the BBG's accomplishments and news and developments affecting the Agency's work. Now, for the first time, this monthly update...

  13. AEB highlights

    International Nuclear Information System (INIS)

    1977-01-01

    AEB HIGHLIGHTS is a half yearly report reflecting the most important recent achievements of the various Research and Technical Divisions of the Atomic Energy Board. It appears alternately in English and Afrikaans [af

  14. Problems and limitations of eddy current tube inspection

    International Nuclear Information System (INIS)

    Ilham Mukriz Zainal Abidin; Khairul Anuar Mohd Salleh; Mohamed Hairul Hasmoni

    2003-01-01

    Incomplete appreciation of eddy current limitations has contributed to both under-utilization and misapplication of the technique. A brief review on the physical principle of eddy current is presented. Eddy current technique in identifying inhomogeneity in tested tubes is discussed, highlighting its limitation in distinguishing between real pit type defects and other mundane anomalies. The variables responsible for limitation in eddy current tube inspection are discussed and alternative approaches, where they exist, are suggested. (Author)

  15. Brookhaven highlights

    International Nuclear Information System (INIS)

    Rowe, M.S.; Belford, M.; Cohen, A.; Greenberg, D.; Seubert, L.

    1993-01-01

    This report highlights the research activities of Brookhaven National Laboratory during the period dating from October 1, 1992 through September 30, 1993. There are contributions to the report from different programs and departments within the laboratory. These include technology transfer, RHIC, Alternating Gradient Synchrotron, physics, biology, national synchrotron light source, applied science, medical science, advanced technology, chemistry, reactor physics, safety and environmental protection, instrumentation, and computing and communications

  16. Two independent pivotal statistics that test location and misspecification and add-up to the Anderson-Rubin statistic

    NARCIS (Netherlands)

    Kleibergen, F.R.

    2002-01-01

    We extend the novel pivotal statistics for testing the parameters in the instrumental variables regression model. We show that these statistics result from a decomposition of the Anderson-Rubin statistic into two independent pivotal statistics. The first statistic is a score statistic that tests

  17. Symposium Highlights

    International Nuclear Information System (INIS)

    Owen-Whitred, K.

    2015-01-01

    Overview/Highlights: To begin, I'd like to take a moment to highlight some of the novel elements of this Symposium as compared to those that have been held in the past. For the first time ever, this Symposium was organized around five concurrent sessions, covering over 300 papers and presentations. These sessions were complemented by an active series of exhibits put on by vendors, universities, ESARDA, INMM, and Member State Support Programmes. We also had live demonstrations throughout the week on everything from software to destructive analysis to instrumentation, which provided the participants the opportunity to see recent developments that are ready for implementation. I'm sure you all had a chance to observe - and, more importantly, interact with - the electronic Poster, or ePoster format used this past week. This technology was used here for the first time ever by the IAEA, and I'm sure was a first for many of us as well. The ePoster format allowed participants to interact with the subject matter, and the subject matter experts, in a dynamic, engaging way. In addition to the novel technology used here, I have to say that having the posters strategically embedded in the sessions on the same topic, by having each poster author introduce his or her topic to the assembled group in order to lure us to the poster area during the breaks, was also a novel and highly effective technique. A final highlight I'd like to touch on in terms of the Symposium organization is the diversity of participation. This chart shows the breakdown by geographical distribution for the Symposium, in terms of participants. There are no labels, so don't try to read any, I simply wanted to demonstrate that we had great representation in terms of both the Symposium participants in general and the session chairs more specifically-and on that note, I would just mention here that 59 Member States participated in the Symposium. But what I find especially interesting and

  18. Eddy current seminar

    International Nuclear Information System (INIS)

    Emson, C.R.I.

    1988-11-01

    The paper presents the fifth symposium in the series of Eddy Current Seminars, held in Abingdon, 1988. The meeting included a discussion on three-dimensional eddy current formulations, as well as thirteen contributed papers on computational electromagnetics. Of the thirteen papers, two papers on eddy currents in tokamaks were selected for INIS and indexed separately. (U.K.)

  19. Eddy current inspection on heat exchanger tubes - problems and limitations

    International Nuclear Information System (INIS)

    Ilham Mukriz; Zainal Abidin Mohamed; Hairul Hasmoni Khairul Anuar; Mohd Salleh; Mahmood Dollah

    2005-01-01

    This paper focus on problems associated to eddy current inspection of heat exchanger tubes. A brief review on heat exchanger design and operation is presented. Eddy current technique in identifying inhomogeneity in tested tubes is discussed, highlighting its limitation in distinguishing between real pit type defects and other mundane anomalies. The limitation of the eddy current probe and equipment pertinent to the inspection are identified and areas of improvement are discussed. (Author)

  20. Eddie Rocket's Franchise

    OpenAIRE

    Vahter, Jenni

    2008-01-01

    Eddie Rocket's Franchise - Setting up a franchise restaurant in Helsinki. TIIVISTELMÄ: Eddie Rocket's on menestynyt amerikkalaistyylinen 1950-luvun ”diner” franchiseravintolaketju Irlannista. Ravintoloita on perustettu viimeisen 18 vuoden aikana 28 kappaletta Irlantiin ja Isoon Britanniaan sekä yksi Espanjaan. Tämän tutkimuksen tarkoitus on tutkia onko Eddie Rocket'silla potentiaalia menestyä Helsingissä, Suomessa. Tutkimuskysymystä on lähestytty toimiala-analyysin, markkinatutkimuksen j...

  1. Eddies off the Queen Charlotte Islands

    Science.gov (United States)

    2002-01-01

    The bright red, green, and turquoise patches to the west of British Columbia's Queen Charlotte Islands and Alaska's Alexander Archipelago highlight the presence of biological activity in the ocean. These colors indicate high concentrations of chlorophyll, the primary pigment found in phytoplankton. Notice that there are a number of eddies visible in the Pacific Ocean in this pseudo-color scene. The eddies are formed by strong outflow currents from rivers along North America's west coast that are rich in nutrients from the springtime snowmelt running off the mountains. This nutrient-rich water helps stimulate the phytoplankton blooms within the eddies. (For more details, read Tracking Eddies that Feed the Sea.) To the west of the eddies in the water, another type of eddy-this one in the atmosphere-forms the clouds into the counterclockwise spiral characteristic of a low pressure system in the Northern Hemisphere. (Click on the image above to see it at full resolution; or click to see the scene in true-color.) The snow-covered mountains of British Columbia are visible in the upper righthand corner of the image. This scene was constructed using SeaWiFS data collected on June 13, 2002. SeaWiFS image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  2. Eddy current testing

    Energy Technology Data Exchange (ETDEWEB)

    Song, Sung Jin; Lee, Hyang Beom; Kim, Young Hwan [Soongsil Univ., Seoul (Korea, Republic of); Shin, Young Kil [Kunsan Univ., Gunsan (Korea, Republic of)

    2004-02-15

    Eddy current testing has been widely used for non destructive testing of steam generator tubes. In order to retain reliability in ECT, the following subjects were carried out in this study: numerical modeling and analysis of defects by using BC and RPC probes in SG tube, preparation of absolute coil impedance plane diagram by FEM. Signal interpretation of the eddy current signals obtained from nuclear power plants.

  3. Eddy current testing

    International Nuclear Information System (INIS)

    Song, Sung Jin; Lee, Hyang Beom; Kim, Young Hwan; Shin, Young Kil

    2004-02-01

    Eddy current testing has been widely used for non destructive testing of steam generator tubes. In order to retain reliability in ECT, the following subjects were carried out in this study: numerical modeling and analysis of defects by using BC and RPC probes in SG tube, preparation of absolute coil impedance plane diagram by FEM. Signal interpretation of the eddy current signals obtained from nuclear power plants

  4. Comparison of Benedict-Webb-Rubin, Starling and Lee-Kesler equations of state for use in P-V-T calculations

    International Nuclear Information System (INIS)

    McFee, D.G.; Mueller, K.H.; Lielmezs, J.

    1982-01-01

    By means of the available experimental gas compressibility data, the predictive accuracy of the Benedict-Webb-Rubin, Starling and Lee-Kesler equations was tested over wide temperature and pressure ranges for the following commonly used industrial gases: CH 4 , C 2 H 6 , C 3 H 8 , CO 2 , Ar, He, H 2 and N 2 . The root mean square (RMS) percent errors calculated over the T-P range investigated for all compounds, showed a degree of superiority and ease of use of the Lee-Kesler equation over the Benedict-Webb-Rubin and Starling equations. In order to treat quantal fluids H 2 and He, the Benedict-Webb-Rubin equation was modified by making constant B 0 temperature dependent, while the Starling and Lee-Kesler equations were rewritten through inclusion of quantum effect corrected pseudo-critical state parameters. (orig.)

  5. Influence of rub-in technique on required application time and hand coverage in hygienic hand disinfection

    Directory of Open Access Journals (Sweden)

    Feil Yvonne

    2008-10-01

    Full Text Available Abstract Background Recent data indicate that full efficacy of a hand rub preparation for hygienic hand disinfection can be achieved within 15 seconds (s. However, the efficacy test used for the European Norm (EN 1500 samples only the fingertips. Therefore, we investigated hand coverage using sixteen different application variations. The hand rub was supplemented with a fluorescent dye, and hands were assessed under UV light by a blind test, before and after application. Fifteen non-healthcare workers were used as subjects for each application variation apart from one test which was done with a group of twenty healthcare workers. All tests apart from the reference procedure were performed using 3 mL of hand rub. The EN 1500 reference procedure, which consists of 6 specific rub-in steps performed twice with an aliquot of 3 ml each time, served as a control. In one part of this study, each of the six steps was performed from one to five times before proceeding to the next step. In another part of the study, the entire sequence of six steps was performed from one to five times. Finally, all subjects were instructed to cover both hands completely, irrespective of any specific steps ("responsible application". Each rub-in technique was evaluated for untreated skin areas. Results The reference procedure lasted on average 75 s and resulted in 53% of subjects with at least one untreated area on the hands. Five repetitions of the rub-in steps lasted on average 37 s with 67% of subjects having incompletely treated hands. One repetition lasted on average 17 s, and all subjects had at least one untreated area. Repeating the sequence of steps lasted longer, but did not yield a better result. "Responsible application" was quite fast, lasting 25 s among non-healthcare worker subjects and 28 s among healthcare workers. It was also effective, with 53% and 55% of hands being incompletely treated. New techniques were as fast and effective as "responsible

  6. Interview with Eddie Reisch

    Science.gov (United States)

    Owen, Hazel

    2013-01-01

    Eddie Reisch is currently working as a policy advisor for Te Reo Maori Operational Policy within the Student Achievement group with the Ministry of Education in New Zealand, where he has implemented and led a range of e-learning initiatives and developments, particularly the Virtual Learning Network (VLN). He is regarded as one of the leading…

  7. Eddy energy separator

    Energy Technology Data Exchange (ETDEWEB)

    Mukhutdinov, R.Kh.; Prokopov, O.I.

    1982-01-01

    An eddy energy separator is proposed which contains a chamber with nozzle input of compressed air and sleeves for cold and hot streams. In order to increase productivity, the chamber is cylindrical and the nozzle input is arranged along its axis. Coaxially to the input, there is an adaptor forming an annular channel with its end arranged in an angle to the axis of the chamber. The nozzle input and the adaptor are installed with the possibility of relative movement.

  8. Eddy Powell 1939 - 2003

    CERN Multimedia

    2003-01-01

    We were saddened to learn that Eddy Powell had passed away on Saturday 26 July after a long illness. Eddy had so many friends at CERN and made such a contribution to the Organisation that it is impossible that his passing goes without comment. Eddy was born in England on 4 August 1939 and, after serving his apprenticeship with the U.K. Ministry of Defence, he joined CERN in September 1965. As an electrical design draftsman with the Synchro-cyclotron Division he played an important role in the upgrades of that machine in the early 1970's, particularly on the RF systems and later on the development of the ISOLDE facility. This brought him into close contact with many of the technical support services in CERN and, unlike many of his compatriots, he acquired a remarkably good fluency in French. Always inquisitive on the physics carried out at CERN, he spent a great deal of time learning from physicists and engineers at all levels. When he felt sufficiently confident he became a CERN Guide for general public visit...

  9. EDDIE RICKENBACKER: RACETRACK ENTREPRENEUR

    Directory of Open Access Journals (Sweden)

    W. David Lewis

    2000-01-01

    Full Text Available Edward V. (Eddie Rickenbacker (1890-1973 is best remembered for hisrecord as a combat pilot in World War I, in which he shot down 26 Germa naircraft and won fame as America’s "Ace of Aces." From 1934 until 1963 he was general manager, president, and board chairman of Eastern Air Lines, which was for a time the most profitable air carrier in the United States. This paper shows how Rickenbacker’s fiercely entrepreneurial style of management was born in his early involvement in the automobile industry, and particularly in his career as an automobile racing driver from 1909 through 1916.

  10. Conditional Eddies in Plasma Turbulence

    DEFF Research Database (Denmark)

    Johnsen, Helene; Pécseli, Hans; Trulsen, J.

    1986-01-01

    Conditional structures, or eddies, in turbulent flows are discussed with special attention to electrostatic turbulence in plasmas. The potential variation of these eddies is obtained by sampling the fluctuations only when a certain condition is satisfied in a reference point. The resulting...

  11. Eddy current manual, volume 2

    International Nuclear Information System (INIS)

    Cecco, V.S.; Van Drunen, G.; Sharp, F.L.

    1984-09-01

    This report on eddy current testing is divided into three sections: (a) Demonstration of Basic Principles, (b) Practical (Laboratory) Tests and, (c) Typical Certification Questions. It is intended to be used as a supplement to ΣEddy Current Manual, Volume 1Σ (AECL-7523) during CSNDT Foundation Level II and III courses

  12. Modeling mesoscale eddies

    Science.gov (United States)

    Canuto, V. M.; Dubovikov, M. S.

    Mesoscale eddies are not resolved in coarse resolution ocean models and must be modeled. They affect both mean momentum and scalars. At present, no generally accepted model exists for the former; in the latter case, mesoscales are modeled with a bolus velocity u∗ to represent a sink of mean potential energy. However, comparison of u∗(model) vs. u∗ (eddy resolving code, [J. Phys. Ocean. 29 (1999) 2442]) has shown that u∗(model) is incomplete and that additional terms, "unrelated to thickness source or sinks", are required. Thus far, no form of the additional terms has been suggested. To describe mesoscale eddies, we employ the Navier-Stokes and scalar equations and a turbulence model to treat the non-linear interactions. We then show that the problem reduces to an eigenvalue problem for the mesoscale Bernoulli potential. The solution, which we derive in analytic form, is used to construct the momentum and thickness fluxes. In the latter case, the bolus velocity u∗ is found to contain two types of terms: the first type entails the gradient of the mean potential vorticity and represents a positive contribution to the production of mesoscale potential energy; the second type of terms, which is new, entails the velocity of the mean flow and represents a negative contribution to the production of mesoscale potential energy, or equivalently, a backscatter process whereby a fraction of the mesoscale potential energy is returned to the original reservoir of mean potential energy. This type of terms satisfies the physical description of the additional terms given by [J. Phys. Ocean. 29 (1999) 2442]. The mesoscale flux that enters the momentum equations is also contributed by two types of terms of the same physical nature as those entering the thickness flux. The potential vorticity flux is also shown to contain two types of terms: the first is of the gradient-type while the other terms entail the velocity of the mean flow. An expression is derived for the mesoscale

  13. Experiments with eddy currents: the eddy current brake

    International Nuclear Information System (INIS)

    Gonzalez, Manuel I

    2004-01-01

    A moderate-cost experimental setup is presented to help students to understand some qualitative and quantitative aspects of eddy currents. The setup operates like an eddy current brake, a device commonly used in heavy vehicles to dissipate kinetic energy by generating eddy currents. A set of simple experiments is proposed to measure eddy current losses and to relate them to various relevant parameters. Typical results for each of the experiments are presented, and comparisons with theoretical predictions are included. The experiments, which are devoted to first-year undergraduate students, deal also with other pedagogically relevant topics in electricity and magnetism, such as basic laws, electrical measurement techniques, the sources of the magnetic field and others

  14. GUIDING NONLINEAR FORCE-FREE MODELING USING CORONAL OBSERVATIONS: FIRST RESULTS USING A QUASI-GRAD-RUBIN SCHEME

    Energy Technology Data Exchange (ETDEWEB)

    Malanushenko, A. [Department of Physics, Montana State University, Bozeman, MT (United States); Schrijver, C. J.; DeRosa, M. L. [Lockheed Martin Advanced Technology Center, Palo Alto, CA (United States); Wheatland, M. S.; Gilchrist, S. A. [Sydney Institute for Astronomy, School of Physics, University of Sydney (Australia)

    2012-09-10

    At present, many models of the coronal magnetic field rely on photospheric vector magnetograms, but these data have been shown to be problematic as the sole boundary information for nonlinear force-free field extrapolations. Magnetic fields in the corona manifest themselves in high-energy images (X-rays and EUV) in the shapes of coronal loops, providing an additional constraint that is not at present used as constraints in the computational domain, directly influencing the evolution of the model. This is in part due to the mathematical complications of incorporating such input into numerical models. Projection effects, confusion due to overlapping loops (the coronal plasma is optically thin), and the limited number of usable loops further complicate the use of information from coronal images. We develop and test a new algorithm to use images of coronal loops in the modeling of the solar coronal magnetic field. We first fit projected field lines with those of constant-{alpha} force-free fields to approximate the three-dimensional distribution of currents in the corona along a sparse set of trajectories. We then apply a Grad-Rubin-like iterative technique, which uses these trajectories as volume constraints on the values of {alpha}, to obtain a volume-filling nonlinear force-free model of the magnetic field, modifying a code and method presented by Wheatland. We thoroughly test the technique on known analytical and solar-like model magnetic fields previously used for comparing different extrapolation techniques and compare the results with those obtained by currently available methods relying only on the photospheric data. We conclude that we have developed a functioning method of modeling the coronal magnetic field by combining the line-of-sight component of the photospheric magnetic field with information from coronal images. Whereas we focus on the use of coronal loop information in combination with line-of-sight magnetograms, the method is readily extended to

  15. GUIDING NONLINEAR FORCE-FREE MODELING USING CORONAL OBSERVATIONS: FIRST RESULTS USING A QUASI-GRAD-RUBIN SCHEME

    International Nuclear Information System (INIS)

    Malanushenko, A.; Schrijver, C. J.; DeRosa, M. L.; Wheatland, M. S.; Gilchrist, S. A.

    2012-01-01

    At present, many models of the coronal magnetic field rely on photospheric vector magnetograms, but these data have been shown to be problematic as the sole boundary information for nonlinear force-free field extrapolations. Magnetic fields in the corona manifest themselves in high-energy images (X-rays and EUV) in the shapes of coronal loops, providing an additional constraint that is not at present used as constraints in the computational domain, directly influencing the evolution of the model. This is in part due to the mathematical complications of incorporating such input into numerical models. Projection effects, confusion due to overlapping loops (the coronal plasma is optically thin), and the limited number of usable loops further complicate the use of information from coronal images. We develop and test a new algorithm to use images of coronal loops in the modeling of the solar coronal magnetic field. We first fit projected field lines with those of constant-α force-free fields to approximate the three-dimensional distribution of currents in the corona along a sparse set of trajectories. We then apply a Grad-Rubin-like iterative technique, which uses these trajectories as volume constraints on the values of α, to obtain a volume-filling nonlinear force-free model of the magnetic field, modifying a code and method presented by Wheatland. We thoroughly test the technique on known analytical and solar-like model magnetic fields previously used for comparing different extrapolation techniques and compare the results with those obtained by currently available methods relying only on the photospheric data. We conclude that we have developed a functioning method of modeling the coronal magnetic field by combining the line-of-sight component of the photospheric magnetic field with information from coronal images. Whereas we focus on the use of coronal loop information in combination with line-of-sight magnetograms, the method is readily extended to incorporate

  16. Vessel eddy current characteristics in SST-1 tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Jana, Subrata; Pradhan, Subrata, E-mail: pradhan@ipr.res.in; Dhongde, Jasraj; Masand, Harish

    2016-11-15

    Highlights: • Eddy current distribution in the SST-1 vacuum vessel. • Circuit model analysis of eddy current. • A comparison of the field lines with and without the plasma column in identical conditions. • The influence of eddy current in magnetic NULL dynamics. - Abstract: Eddy current distribution in the vacuum vessel of the Steady state superconducting (SST-1) tokamak has been determined from the experimental data obtained using an array of internal voltage loops (flux loop) installed inside the vacuum vessel. A simple circuit model has been employed. The model takes into account the geometric and constructional features of SST-1 vacuum vessel. SST-1 vacuum vessel is a modified ‘D’ shaped vessel having major axis of 1.285 m and minor axis of 0.81 m and has been manufactured from non-magnetic stainless steel. The Plasma facing components installed inside the vacuum vessel are graphite blocks mounted on Copper Chromium Zirconium (CuCrZr) heat sink plates on inconel supports. During discharge of the central solenoid, eddy currents get generated in the vacuum vessel and passive supports on it. These eddy currents influence the early magnetic NULL dynamics and plasma break-down and start-up characteristics. The computed results obtained from the model have been benchmarked against experimental data obtained in large number of SST-1 plasma shots. The results are in good agreement. Once bench marked, the calculated eddy current based on flux loop signal and circuit equation model has been extended to the reconstruction of the overall B- field contours of SST-1 tokamak in the vessel region. A comparison of the field lines with and without the plasma column in identical conditions of the central solenoid and equilibrium field profiles has also been done with an aim to quantify the diagnostics responses in vacuum shots.

  17. ATLAS Outreach Highlights

    CERN Document Server

    Cheatham, Susan; The ATLAS collaboration

    2016-01-01

    The ATLAS outreach team is very active, promoting particle physics to a broad range of audiences including physicists, general public, policy makers, students and teachers, and media. A selection of current outreach activities and new projects will be presented. Recent highlights include the new ATLAS public website and ATLAS Open Data, the very recent public release of 1 fb-1 of ATLAS data.

  18. Studies Highlight Biodiesel's Benefits

    Science.gov (United States)

    , Colo., July 6, 1998 — Two new studies highlight the benefits of biodiesel in reducing overall air Energy's National Renewable Energy Laboratory (NREL) conducted both studies: An Overview of Biodiesel and Petroleum Diesel Life Cycles and Biodiesel Research Progress, 1992-1997. Biodiesel is a renewable diesel

  19. Mesoscale eddies in the Subantarctic Front-Southwest Atlantic

    Directory of Open Access Journals (Sweden)

    Pablo D. Glorioso

    2005-12-01

    Full Text Available Satellite and ship observations in the southern southwest Atlantic (SSWA reveal an intense eddy field and highlight the potential for using continuous real-time satellite altimetry to detect and monitor mesoscale phenomena with a view to understanding the regional circulation. The examples presented suggest that mesoscale eddies are a dominant feature of the circulation and play a fundamental role in the transport of properties along and across the Antarctic Circumpolar Current (ACC. The main ocean current in the SSWA, the Falkland-Malvinas Current (FMC, exhibits numerous embedded eddies south of 50°S which may contribute to the patchiness, transport and mixing of passive scalars by this strong, turbulent current. Large eddies associated with meanders are observed in the ACC fronts, some of them remaining stationary for long periods. Two particular cases are examined using a satellite altimeter in combination with in situ observations, suggesting that cross-frontal eddy transport and strong meandering occur where the ACC flow intensifies along the sub-Antarctic Front (SAF and the Southern ACC Front (SACCF.

  20. Clinical highlights from Amsterdam

    Directory of Open Access Journals (Sweden)

    Jouke T. Annema

    2016-07-01

    Full Text Available This article contains highlights and a selection of the scientific advances from the Clinical Assembly that were presented at the 2015 European Respiratory Society International Congress in Amsterdam, the Netherlands. The most relevant topics for clinicians will be discussed, covering a wide range of areas including interventional pulmonology, rehabilitation and chronic care, thoracic imaging, diffuse and parenchymal lung diseases, and general practice and primary care. In this comprehensive review, exciting novel data will be discussed and put into perspective.

  1. FY 2016 Research Highlights

    Energy Technology Data Exchange (ETDEWEB)

    2017-03-23

    This fact sheet summarizes the research highlights for the Clean Energy Manufacturing Analysis Center (CEMAC) for Fiscal Year 2106. Topics covered include additive manufacturing for the wind industry, biomass-based chemicals substitutions, carbon fiber manufacturing facility siting, geothermal power plant turbines, hydrogen refueling stations, hydropower turbines, LEDs and lighting, light-duty automotive lithium-ion cells, magnetocaloric refrigeration, silicon carbide power electronics for variable frequency motor drives, solar photovoltaics, and wide bandgap semiconductor opportunities in power electronics.

  2. IGC highlights 1988

    International Nuclear Information System (INIS)

    1989-01-01

    The major thrust of the research and development (R and D) activities of the Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam is oriented towards mastering fast breeder reactor (FBR) technology. Towards this end, its current R and D activities are carried out in a wide variety of disciplines. Highlights of its R and D activities during 1988 are summarised under the headings: Reactor Engineering and Design, Reactor Physics and Safety, Materials Science and Technology, Sodium Chemistry and Technology, Fuel Reprocessing and Electronics and Instrumentation. The text is illustrated with a number of figures, graphs and coloured pictures. (M.G.B.). figs., tabs

  3. BARC highlights '88

    International Nuclear Information System (INIS)

    1989-01-01

    Highlights of research and development activities of the Bhabha Atomic Research Centre (BARC), Bombay during 1988 are presented in chapters entitled: Physical Sciences, Chemical Sciences, Materials and Materials Sciences, Radioisotopes, Reactors, Fuel Cycle, Radiological Safety and Protection, Electronics and Instrumentation, Engineering Services, and Life Sciences. Main thrust of the R and D activities of BARC is on nuclear power reactor technology and all stages of nuclear fuel cycle. Some activities are also in the frontier areas such as high temperature superconductivity and inertial confinement fusion. (M.G.B.). figs., tabs., coloured ills

  4. An avenue of eddies: Quantifying the biophysical properties of mesoscale eddies in the Tasman Sea

    Science.gov (United States)

    Everett, J. D.; Baird, M. E.; Oke, P. R.; Suthers, I. M.

    2012-08-01

    The Tasman Sea is unique - characterised by a strong seasonal western boundary current that breaks down into a complicated field of mesoscale eddies almost immediately after separating from the coast. Through a 16-year analysis of Tasman Sea eddies, we identify a region along the southeast Australian coast which we name ‘Eddy Avenue’ where eddies have higher sea level anomalies, faster rotation and greater sea surface temperature and chlorophyll a anomalies. The density of cyclonic and anticyclonic eddies within Eddy Avenue is 23% and 16% higher respectively than the broader Tasman Sea. We find that Eddy Avenue cyclonic and anticyclonic eddies have more strongly differentiated biological properties than those of the broader Tasman Sea, as a result of larger anticyclonic eddies formed from Coral Sea water depressing chl. a concentrations, and for coastal cyclonic eddies due to the entrainment of nutrient-rich shelf waters. Cyclonic eddies within Eddy Avenue have almost double the chlorophyll a (0.35 mg m-3) of anticyclonic eddies (0.18 mg m-3). The average chlorophyll a concentration for cyclonic eddies is 16% higher in Eddy Avenue and 28% lower for anticyclonic eddies when compared to the Tasman Sea. With a strengthening East Australian Current, the propagation of these eddies will have significant implications for heat transport and the entrainment and connectivity of plankton and larval fish populations.

  5. Study on classical and excess eddy currents losses of Terfenol-D

    Energy Technology Data Exchange (ETDEWEB)

    Talebian, Soheil; Hojjat, Yousef [Department of Mechanical Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Ghodsi, Mojtaba [Department of Mechanical and Industrial Engineering, Sultan Qaboos University, Muscat (Oman); Karafi, Mohammad Reza [Department of Mechanical Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2015-08-15

    In the present paper, classical and excess eddy currents losses of Terfenol-D are studied and effects of magnetic field frequency, peak of magnetic flux density and diameter of Terfenol-D on the eddy currents losses are investigated. To provide reliable data for the purpose of the paper, an experimental laboratory is fabricated and used to obtain major and minor hysteresis loops of Terfenol-D at different frequencies. In theoretical study, initially an analytical model based on uniform distribution of magnetic flux is developed which yields to calculation of classical eddy currents losses. Then, another eddy currents model based on non-uniform distribution of magnetic flux and nonlinear diffusion of electromagnetic fields is presented. The difference between output values of the two models is identified as excess eddy currents losses. Obtained results show that the values of excess losses are generally larger than classical losses and applying just classical model leads to wrong calculation of actual value of eddy currents losses. For the results obtained from two above models, empirical models with respect to the magnetic field frequency and the peak value of magnetic flux density are achieved which can predict the eddy currents losses precisely. To validate the empirical relations, experiments are repeated at a new frequency and values of power losses calculated from analytical equations are compared with the predicted values of the empirical models. The results point towards possibility to use the obtained empirical relations in order to calculate the classical and excess eddy currents losses of Terfenol-D at the frequencies below 200 Hz and different values of magnetic flux density. - Highlights: • Classical eddy currents loss of Terfenol-D is studied using Maxwell's laws. • Excess eddy currents loss of Terfenol-D is studied using Mayergoyz nonlinear model. • Effects of Terfenol-D geometry on the eddy currents losses are investigated. • Power

  6. Remote field eddy current testing

    International Nuclear Information System (INIS)

    Cheong, Y. M.; Jung, H. K.; Huh, H.; Lee, Y. S.; Shim, C. M.

    2001-03-01

    The state-of-art technology of the remote field eddy current, which is actively developed as an electromagnetic non-destructive testing tool for ferromagnetic tubes, is described. The historical background and recent R and D activities of remote-field eddy current technology are explained including the theoretical development of remote field eddy current, such as analytical and numerical approach, and the results of finite element analysis. The influencing factors for actual applications, such as the effect of frequency, magnetic permeability, receiving sensitivity, and difficulties of detection and classification of defects are also described. Finally, two examples of actual application, 1) the gap measurement between pressure tubes and calandria tube in CANDU reactor and, 2) the detection of defects in the ferromagnetic heat exchanger tubes, are described. The future research efforts are also included

  7. Highlights from CMS

    CERN Document Server

    Autermann, Christian

    2018-01-01

    This article summarizes the latest highlights from the CMS experiment as presented at the Lepton Photon conference 2017 in Guangzhou, China. A selection of the latest physics results, the latest detector upgrades, and the current detector status are discussed. CMS has analyzed the full dataset of proton-proton collision data delivered by the LHC in 2016 at a center-of-mass energy of $13$\\,TeV corresponding to an integrated luminosity of $40$\\,fb$^{-1}$. The leap in center-of-mass energy and in luminosity with respect to the $7$ and $8$\\,TeV runs enabled interesting and relevant new physics results. A new silicon pixel tracking detector was installed during the LHC shutdown 2016/17 and has successfully started operation.

  8. PSI scientific highlights 2012

    International Nuclear Information System (INIS)

    Piwnicki, P.; Dury, T.

    2013-05-01

    This comprehensive report issued by the Paul Scherrer Institute (PSI) reviews research in various areas carried out by the institute in 2012. Also, the various facilities to be found at the institute are described. Research focus and highlights are discussed. These include work done using synchrotron light, neutrons and muons as well as work done in the particle physics, microtechnology and nanotechnology areas. Further areas of research include biomolecular research, radiopharmacy, radiochemistry and environmental chemistry. Other areas covered include general energy research and work done at the Competence Center for Energy and Mobility CCEM, work done on nuclear energy safety as well as systems analysis in the environmental and energy areas. The report is concluded with facts and figures on the PSI, its Advisory Board and its organisational structures

  9. PSI scientific highlights 2011

    International Nuclear Information System (INIS)

    Piwnicki, P.

    2012-04-01

    This comprehensive report for the Swiss Federal Office of Energy (SFOE) presents the major highlights of the work done at the Paul Scherrer Institute, Switzerland, in 2011. According to the institute's director, work was concerned with the design and analysis of advanced materials with new functionalities, for application in fields as diverse as communications and energy technology, transportation, construction and medicine. Of particular topical interest are research projects on materials for application in the field of energy, for example for improving batteries for future electrically powered vehicles. Another example is in the field of catalysts. Environmentally harmful compounds, such as nitrogen oxide and sulphur dioxide produced in an engine, are transformed into nontoxic gases through catalytic conversion. Work progress on the SwissFEL installation is noted, including a breakthrough for SwissFEL main Linac C-band accelerating systems. Further topics in relation to the SwissFEL system are noted. Planning of the initial set of experimental stations at the SwissFEL is discussed and close collaboration with growing number of user communities is noted. Cross-Correlation Scattering, and a theoretical framework for this method is being developed and experimentally verified, using artificial nanostructures and synchrotron radiation. Highlights of further research work are discussed, including topics such as Synchrotron light, work done on neutrons and muons, particle physics, micro and nanotechnology as well as on biomolecular research and radiopharmacy. Large research facilities are discussed as is the PSI proton therapy installation. General energy topics are looked at, as are nuclear energy and safety aspects and environmental and energy systems analysis. Various further work includes factors causing glacier retreat and aerosols. User facilities are listed, including accelerators, the SLS light source, the SINQ neutron source, the UCN ultra-cold neutron source

  10. Eddy currents in accelerator magnets

    CERN Document Server

    Moritz, G

    2010-01-01

    This paper covers the main eddy current effects in accelerator magnets - field modification (time delay and field quality) and resistive power losses. In the first part, starting from the Maxwell equations, a basic understanding of the processes is given and explained with examples of simple geometry and time behaviour. Useful formulas are derived for an analytic estimate of the size of the effects. In the second part the effects in real magnets are analysed and described in comparison with numerical and measured results. Finally, based on the previous parts, design recommendations are given regarding how to minimize eddy current effects.

  11. Eddy current inspection of tubing

    International Nuclear Information System (INIS)

    Bauza, J. L. R.; Herrero, J.; Diaz, J.

    1966-01-01

    The Experimental research work carried out to develop a Eddy current testing equipment is described. Search coils with ferrite or air cores were used and the obtained results are discussed. Valuable information was gained from a improved channel in which a direct measure of the defect and the reference signal phase difference is obtained. Artificial defect used to evaluate resolution and sensitivity were produced by electro-machining and mechanical means. Finned SAP tubing was tested in a routine basis with the described equipment and the results plotted. Basic and theoretical considerations on the Eddy current testing technique are given in the last section of this report. (Author)

  12. A Baroclinic Eddy Mixer: Supercritical Transformation of Compensated Eddies

    Science.gov (United States)

    Sutyrin, G.

    2016-02-01

    In contrast to many real-ocean rings and eddies, circular vortices with initial lower layer at rest tend to be highly unstable in idealized two-layer models, unless their radius is made small or the lower layer depth is made artificially large. Numerical simulations of unstable vortices with parameters typical for ocean eddies revealed strong deformations and pulsations of the vortex core in the two-layer setup due to development of corotating tripolar structures in the lower layer during their supercritical transformation. The addition of a middle layer with the uniform potential vorticity weakens vertical coupling between the upper and lower layer that enhances vortex stability and makes the vortex lifespan more realistic. Such a three-layer vortex model possesses smaller lower interface slope than the two-layer model that reduces the potential vorticity gradient in the lower layer and provides with less unstable configurations. While cyclonic eddies become only slightly deformed and look nearly circular when the middle layer with uniform potential vorticity is added, anticyclonic eddies tend to corotating and pulsating elongated states through potential vorticity stripping and stirring. Enhanced vortex stability in such three-layer setup has important implications for adequate representation of the energy transfer across scales.

  13. RESEARCH HIGHLIGHTS IN IAS

    Directory of Open Access Journals (Sweden)

    Marko Kreft

    2017-03-01

    Full Text Available We are reviewing and commenting highlights of the research published in Image Analysis and Stereology journal (IAS, volume 35, where 16 original research papers on image analysis, computer vision, modelling, and other approaches were published. We have reported on the precision of curve length estimation in the plane. Further, a focus was on a robust estimation technique for 3D point cloud registration. Next contribution in computer vision was on the accuracy of stereo matching algorithm based on illumination control. An attempt was also made to automatically diagnose prenatal cleft lip with representative key points and identify the type of defect in three-dimensional ultrasonography. Similarly, a new report is presenting estimation of torsion of digital curves in 3D images and next, the nuchal translucency by ultrasound is being analyzed. Also in ophthalmology, image analysis may help physicians to establish a correct diagnosis, which is supported by a new approach to measure tortuosity of retinal vessel. Another report of medical significance analyzed correlation of the shape parameters for characterization of images of corneal endothelium cells. Shape analysis is also an important topic in material science, e.g. in analyzing fine aggregates in concrete. As in concrete, in fiber reinforced composites image analysis may aid in improved quality, where the direction of fibers have decisive impact on properties. Automatic defect detection using a computer vision system improves productivity quality in industrial production, hence we report of a new Haar wavelet-based approach.

  14. Large Eddy Simulation of turbulence

    International Nuclear Information System (INIS)

    Poullet, P.; Sancandi, M.

    1994-12-01

    Results of Large Eddy Simulation of 3D isotropic homogeneous turbulent flows are presented. A computer code developed on Connexion Machine (CM5) has allowed to compare two turbulent viscosity models (Smagorinsky and structure function). The numerical scheme influence on the energy density spectrum is also studied [fr

  15. Eddy current manual: v.1

    International Nuclear Information System (INIS)

    Cecco, V.S.; Van Drunen, G.; Sharp, F.L.

    1983-09-01

    This training and reference manual was assembled to provide those involved in eddy current testing with both the fundamental principles of the technique as well as the knowledge to deal with often complicated test results. A non-rigorous approach is used to simplify complex physical phenomena. Emphasis is placed on proper choice of test frequency and signal interpretation. Defect detection and diagnosis receive particular attention. Design and construction of probes are covered extensively since probes play a key role in eddy current testing. The advantages and limitations of various probe types are discussed. Electromagnetic theory, instrumentation, test methods and signal analysis are covered. Simplified derivations of probe response to test parameters are presented to develop a basic understanding of eddy current behaviour. Eddy current signals are presented on impedance plane diagrams throughout the manual since this is the most common display on modern, general purpose instruments. The use of Σphase lagΣ in signal analysis is covered in detail. To supplement theory, practical examples are presented to develop proficiency in performing inspections, and to illustrate how basic principles are applied to diagnose real signals

  16. Eddy current testing, volume 1

    International Nuclear Information System (INIS)

    Cecco, V.S.; Van Drunen, G.; Sharp, F.L.

    1981-11-01

    This training and reference manual was assembled to provide those involved in eddy current testing with both the fundamental principles of the technique as well as the knowledge to deal with often complicated test results. A non-rigorous approach is used to simplify complex physical phenomena. Emphasis is placed on proper choice of test frequency and interpretation. Defect detection and diagnosis receive particular attention. Design and construction of probes are covered extensively since probes play a key role in eddy current testing. The advantages and limitations of various probe types are discussed. Electromagnetic theory, instrumentation, test methods and signal analysis are covered. Simplified derivations of probe response to test parameters are presented to develop a basic understanding of eddy current behaviour. Eddy current signals are presented on impedance plane diagrams throughout the manual since this is the most common display on modern, general purpose instruments. The use of 'phase leg' in signal analysis is covered in detail. To supplement theory, practical examples are presented to develop proficiency in performing inspections, and to illustrate how basic principles are applied to diagnose real signals

  17. Distant Influence of Kuroshio Eddies on North Pacific Weather Patterns?

    Science.gov (United States)

    Ma, Xiaohui; Chang, Ping; Saravanan, R; Montuoro, Raffaele; Hsieh, Jen-Shan; Wu, Dexing; Lin, Xiaopei; Wu, Lixin; Jing, Zhao

    2015-12-04

    High-resolution satellite measurements of surface winds and sea-surface temperature (SST) reveal strong coupling between meso-scale ocean eddies and near-surface atmospheric flow over eddy-rich oceanic regions, such as the Kuroshio and Gulf Stream, highlighting the importance of meso-scale oceanic features in forcing the atmospheric planetary boundary layer (PBL). Here, we present high-resolution regional climate modeling results, supported by observational analyses, demonstrating that meso-scale SST variability, largely confined in the Kuroshio-Oyashio confluence region (KOCR), can further exert a significant distant influence on winter rainfall variability along the U.S. Northern Pacific coast. The presence of meso-scale SST anomalies enhances the diabatic conversion of latent heat energy to transient eddy energy, intensifying winter cyclogenesis via moist baroclinic instability, which in turn leads to an equivalent barotropic downstream anticyclone anomaly with reduced rainfall. The finding points to the potential of improving forecasts of extratropical winter cyclones and storm systems and projections of their response to future climate change, which are known to have major social and economic impacts, by improving the representation of ocean eddy-atmosphere interaction in forecast and climate models.

  18. Development of Multichannel Eddy Current Testing Instrument

    International Nuclear Information System (INIS)

    Lee, Hee Jong; Cho, Chan Hee; Nam, Min Woo; Yoon, Byung Sik; Yoo, Hyun Joo

    2010-01-01

    Four main techniques of electromagnetic testing are used for commercial applications: eddy current testing, alternating current field testing, magnetic flux leakage testing and remote field testing. Eddy current testing is a nondestructive evaluation method, which makes eddy current flow on a specimen by applying driving pulse to eddy current probe coil, by using eddy current testing device, and makes the change of eddy current which is dependently caused by flaws, material characteristics, testing condition, receiving through eddy current, and analyzes material properties, flaws, status on the specimen. Application of EC instrumentation varies widely in industry from the identification of metal heat treatment to the inspection of steam generator tubing in nuclear power plants. In this study, we have designed multichannel EC instrument which can be applicable to the NDE of the tube in heat exchanger for electric power facility, chemistry, and military industry, and finally confirmed the proper function of EC instrumentation

  19. Climatic feedbacks between stationary and transient eddies

    International Nuclear Information System (INIS)

    Branscome, L.E.

    1994-01-01

    Stationary eddies make a significant contribution to poleward heat transport during Northern Hemisphere winter, equaling the transport by transient eddies. On the other hand, stationary eddy transport during the summer is negligible. The effect of topography on time-mean stationary waves and low-frequency variability has been widely studied. In contrast, little attention has been given to the climatic feedbacks associated with stationary eddies. Furthermore, the relationship between stationary and transient eddies in the context of global and regional climate is not well understood. The response of the climate system to anthropogenic forcing is likely to have some dependence on stationary wave transport and its interaction with transient eddies. Some early GCM simulations and observational analyses indicate a strong feedback between the meridional heat fluxes of stationary and transient eddies

  20. Quantitative pulsed eddy current analysis

    International Nuclear Information System (INIS)

    Morris, R.A.

    1975-01-01

    The potential of pulsed eddy current testing for furnishing more information than conventional single-frequency eddy current methods has been known for some time. However, a fundamental problem has been analyzing the pulse shape with sufficient precision to produce accurate quantitative results. Accordingly, the primary goal of this investigation was to: demonstrate ways of digitizing the short pulses encountered in PEC testing, and to develop empirical analysis techniques that would predict some of the parameters (e.g., depth) of simple types of defect. This report describes a digitizing technique using a computer and either a conventional nuclear ADC or a fast transient analyzer; the computer software used to collect and analyze pulses; and some of the results obtained. (U.S.)

  1. High resolution eddy current microscopy

    Science.gov (United States)

    Lantz, M. A.; Jarvis, S. P.; Tokumoto, H.

    2001-01-01

    We describe a sensitive scanning force microscope based technique for measuring local variations in resistivity by monitoring changes in the eddy current induced damping of a cantilever with a magnetic tip oscillating above a conducting sample. To achieve a high sensitivity, we used a cantilever with an FeNdBLa particle mounted on the tip. Resistivity measurements are demonstrated on a silicon test structure with a staircase doping profile. Regions with resistivities of 0.0013, 0.0041, and 0.022 Ω cm are clearly resolved with a lateral resolution of approximately 180 nm. For this range of resistivities, the eddy current induced damping is found to depend linearly on the sample resistivity.

  2. Flexible eddy current coil arrays

    International Nuclear Information System (INIS)

    Krampfner, Y.; Johnson, D.P.

    1987-01-01

    A novel approach was devised to overcome certain limitations of conventional eddy current testing. The typical single-element hand-wound probe was replaced with a two dimensional array of spirally wound probe elements deposited on a thin, flexible polyimide substrate. This provides full and reliable coverage of the test area and eliminates the need for scanning. The flexible substrate construction of the array allows the probes to conform to irregular part geometries, such as turbine blades and tubing, thereby eliminating the need for specialized probes for each geometry. Additionally, the batch manufacturing process of the array can yield highly uniform and reproducible coil geometries. The array is driven by a portable computer-based eddy current instrument, smartEDDY/sup TM/, capable of two-frequency operation, and offers a great deal of versatility and flexibility due to its software-based architecture. The array is coupled to the instrument via an 80-switch multiplexer that can be configured to address up to 1600 probes. The individual array elements may be addressed in any desired sequence, as defined by the software

  3. Local eddy current measurements in pulsed fields

    Energy Technology Data Exchange (ETDEWEB)

    Espina-Hernandez, J.H. [SEPI-Electronica, ESIME-IPN, UPALM Edif. ' Z' . Zacatenco, Mexico DF 07738 (Mexico)], E-mail: jhespina@gmail.com; Groessinger, R. [Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Vienna (Austria); Hallen, J.M. [Departamento de Ingenieria Metalurgica, IPN-ESIQIE, UPALM Edif. 7, Zacatenco, Mexico DF 07738 (Mexico)

    2008-07-15

    This work presents new eddy current measurements in pulsed fields. A commercial point pick-up coil is used to detect the induction signal along the radius of Cu and Al samples with cylindrical shape and diameters between 5 and 35 mm. Local eddy current measurements were performed on the surface of conducting materials due to the small dimensions of the coil. A simple electrical circuit, used as a model, is proposed to describe the local eddy current effect in pulsed fields. The proposed model allows to calculate the phase shift angle between the signal proportional to eddy currents and the applied external field in a pulsed field magnetometer.

  4. A Modified Benedict-Webb-Rubin Equation of State for the Thermodynamic Properties of R152a (1,1-difluoroethane)

    Science.gov (United States)

    Outcalt, Stephanie L.; McLinden, Mark O.

    1996-03-01

    A modified Benedict-Webb-Rubin (MBWR) equation of state has been developed for R152a (1,1-difluoroethane). The correlation is based on a selection of available experimental thermodynamic property data. Single-phase pressure-volume-temperature (PVT), heat capacity, and sound speed data, as well as second virial coefficient, vapor pressure, and saturated liquid and saturated vapor density data, were used with multi-property linear least-squares fitting to determine the 32 adjustable coefficients of the MBWR equation. Ancillary equations representing the vapor pressure, saturated liquid and saturated vapor densities, and the ideal gas heat capacity were determined. Coefficients for the equation of state and the ancillary equations are given. Experimental data used in this work covered temperatures from 162 K to 453 K and pressures to 35 MPa. The MBWR equation established in this work may be used to predict thermodynamic properties of R152a from the triple-point temperature of 154.56 K to 500 K and for pressures up to 60 MPa except in the immediate vicinity of the critical point.

  5. DESY: Handling persistent eddy currents

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1990-04-15

    The vanishing electrical resistance of superconducting coils as well as their ability to provide magnetic fields far beyond those of saturated iron is the main motivation behind the push to use superconducting technology in big new proton accelerators. But this advantage can turn into a drawback at low excitations when the eddy currents - induced in any electromagnet when the field is changed - do not decay, but continue to flow. Preparations for the proton ring of the HERA electron-proton collider nearing completion at the German DESY Laboratory in Hamburg have borne this in mind.

  6. DESY: Handling persistent eddy currents

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    The vanishing electrical resistance of superconducting coils as well as their ability to provide magnetic fields far beyond those of saturated iron is the main motivation behind the push to use superconducting technology in big new proton accelerators. But this advantage can turn into a drawback at low excitations when the eddy currents - induced in any electromagnet when the field is changed - do not decay, but continue to flow. Preparations for the proton ring of the HERA electron-proton collider nearing completion at the German DESY Laboratory in Hamburg have borne this in mind

  7. Ingredients of the Eddy Soup: A Geometric Decomposition of Eddy-Mean Flow Interactions

    Science.gov (United States)

    Waterman, S.; Lilly, J. M.

    2014-12-01

    Understanding eddy-mean flow interactions is a long-standing problem in geophysical fluid dynamics with modern relevance to the task of representing eddy effects in coarse resolution models while preserving their dependence on the underlying dynamics of the flow field. Exploiting the recognition that the velocity covariance matrix/eddy stress tensor that describes eddy fluxes, also encodes information about eddy size, shape and orientation through its geometric representation in the form of the so-called variance ellipse, suggests a potentially fruitful way forward. Here we present a new framework that describes eddy-mean flow interactions in terms of a geometric description of the eddy motion, and illustrate it with an application to an unstable jet. Specifically we show that the eddy vorticity flux divergence F, a key dynamical quantity describing the average effect of fluctuations on the time-mean flow, may be decomposed into two components with distinct geometric interpretations: 1. variations in variance ellipse orientation; and 2. variations in the anisotropic part of the eddy kinetic energy, a function of the variance ellipse size and shape. Application of the divergence theorem shows that F integrated over a region is explained entirely by variations in these two quantities around the region's periphery. This framework has the potential to offer new insights into eddy-mean flow interactions in a number of ways. It identifies the ingredients of the eddy motion that have a mean flow forcing effect, it links eddy effects to spatial patterns of variance ellipse geometry that can suggest the mechanisms underpinning these effects, and finally it illustrates the importance of resolving eddy shape and orientation, and not just eddy size/energy, to accurately represent eddy feedback effects. These concepts will be both discussed and illustrated.

  8. A DDES model with a Smagorinsky-type eddy viscosity formulation and log-layer mismatch correction

    International Nuclear Information System (INIS)

    Reddy, K.R.; Ryon, J.A.; Durbin, P.A.

    2014-01-01

    Highlights: • An alternate DDES formulation is proposed via the eddy viscosity definition. • Eddy viscosity is expressed as a Smagorinsky-type formula. • Log-layer mismatch is corrected by changing the length scale definition. • Model is validated for 2D as well as 3D flows. - Abstract: The current work develops a variant of delayed detached eddy simulation (DDES) that could be characterized as limiting the production term. Previous formulations have been based on limiting the dissipation rate (Spalart et al., 2006). A clipped length scale is applied directly to the eddy viscosity, yielding a Smagorinsky-like formulation when the model is on the eddy simulation branch. That clipped eddy viscosity limits the production rate. The length scale is modified in order to account for the log-layer mismatch (a well-known issue with DDES), without using additional blending functions. Another view of our approach is that the subgrid eddy-viscosity is represented by a mixing length formula l 2 ω; in the eddy field ω acts like a filtered rate of strain. Our model is validated for channel flow as well as separated flows (backward-facing step, 2D periodic hills) and illustrated via an air-blast atomizer

  9. Wind changes above warm Agulhas Current eddies

    CSIR Research Space (South Africa)

    Rouault, M

    2016-01-01

    Full Text Available speeds above the eddies at the instantaneous scale; 20 % of cases had incomplete data due to partial global coverage by the scatterometer for one path. For cases where the wind is stronger above warm eddies, there is no relationship between the increase...

  10. Oceanic eddies in synthetic aperture radar images

    Indian Academy of Sciences (India)

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

    determining mechanism of eddy formation in this case is the vorticity (shear) of the currents or devi- ation of one current by another. Figure 10 shows the ERS-1 SAR image with a couple of cyclonic eddies that is supposedly located in the area of confluence of oppositely directed currents in the central part of the Japan Sea.

  11. Mesoscale Eddies in the Solomon Sea

    Science.gov (United States)

    Hristova, H. G.; Kessler, W. S.; McWilliams, J. C.; Molemaker, M. J.

    2011-12-01

    Water mass transformation in the strong equatorward flows through the Solomon Sea influences the properties of the Equatorial Undercurrent and subsequent cold tongue upwelling. High eddy activity in the interior Solomon Sea seen in altimetric sea surface height (SSH) and in several models may provide a mechanism for these transformations. We investigate these effects using a mesoscale (4-km resolution) sigma-coordinate (ROMS) model of the Solomon Sea nested in a basin solution, forced by a repeating seasonal cycle, and evaluated against observational data. The model generates a vigorous upper layer eddy field; some of these are apparently shed as the New Guinea Coastal Undercurrent threads through the complex topography of the region, others are independent of the strong western boundary current. We diagnose the scales and vertical structure of the eddies in different parts of the Solomon Sea to illuminate their generation processes and propagation characteristics, and compare these to observed eddy statistics. Hypotheses tested are that the Solomon Sea mesoscale eddies are generated locally by baroclinic instability, that the eddies are shed as the South Equatorial Current passes around and through the Solomon Island chain, that eddies are generated by the New Guinea Coastal Undercurrent, or that eddies occurring outside of the Solomon Sea propagate into the Solomon Sea. These different mechanisms have different implications for the resulting mixing and property fluxes. They also provide different interpretations for SSH signals observed from satellites (e.g., that will be observed by the upcoming SWOT satellite).

  12. Eddy current analysis in fusion devices

    International Nuclear Information System (INIS)

    Turner, L.R.

    1988-06-01

    In magnetic fusion devices, particularly tokamaks and reversed field pinch (RFP) experiments, time-varying magnetic fields are in intimate contact with electrically conducting components of the device. Induced currents, fields, forces, and torques result. This note reviews the analysis of eddy current effects in the following systems: Interaction of a tokamak plasma with the eddy currents in the first wall, blanket, and shield (FWBS) systems; Eddy currents in a complex but two-dimensional vacuum vessel, as in TFTR, JET, and JT-60; Eddy currents in the FWBS system of a tokamak reactor, such as NET, FER, or ITER; and Eddy currents in a RFP shell. The cited studies are chosen to be illustrative, rather than exhaustive. 42 refs

  13. Eddy Current Flaw Characterization Using Neural Networks

    International Nuclear Information System (INIS)

    Song, S. J.; Park, H. J.; Shin, Y. K.

    1998-01-01

    Determination of location, shape and size of a flaw from its eddy current testing signal is one of the fundamental issues in eddy current nondestructive evaluation of steam generator tubes. Here, we propose an approach to this problem; an inversion of eddy current flaw signal using neural networks trained by finite element model-based synthetic signatures. Total 216 eddy current signals from four different types of axisymmetric flaws in tubes are generated by finite element models of which the accuracy is experimentally validated. From each simulated signature, total 24 eddy current features are extracted and among them 13 features are finally selected for flaw characterization. Based on these features, probabilistic neural networks discriminate flaws into four different types according to the location and the shape, and successively back propagation neural networks determine the size parameters of the discriminated flaw

  14. Atmospheric Research 2011 Technical Highlights

    Science.gov (United States)

    2012-01-01

    The 2011 Technical Highlights describes the efforts of all members of Atmospheric Research. Their dedication to advancing Earth Science through conducting research, developing and running models, designing instruments, managing projects, running field campaigns, and numerous other activities, is highlighted in this report.

  15. Conformable eddy current array delivery

    Science.gov (United States)

    Summan, Rahul; Pierce, Gareth; Macleod, Charles; Mineo, Carmelo; Riise, Jonathan; Morozov, Maxim; Dobie, Gordon; Bolton, Gary; Raude, Angélique; Dalpé, Colombe; Braumann, Johannes

    2016-02-01

    The external surface of stainless steel containers used for the interim storage of nuclear material may be subject to Atmospherically Induced Stress Corrosion Cracking (AISCC). The inspection of such containers poses a significant challenge due to the large quantities involved; therefore, automating the inspection process is of considerable interest. This paper reports upon a proof-of-concept project concerning the automated NDT of a set of test containers containing artificially generated AISCCs. An Eddy current array probe with a conformable padded surface from Eddyfi was used as the NDT sensor and end effector on a KUKA KR5 arc HW robot. A kinematically valid cylindrical raster scan path was designed using the KUKA|PRC path planning software. Custom software was then written to interface measurement acquisition from the Eddyfi hardware with the motion control of the robot. Preliminary results and analysis are presented from scanning two canisters.

  16. Highlights of nuclear chemistry 1995

    International Nuclear Information System (INIS)

    1996-07-01

    In this report 9 topics of the work of the Nuclear Chemistry Group in 1995 are highlighted. A list of publications and an overview of the international cooperation is given. (orig.). 19 refs., 19 figs., 2 tabs., 2 app

  17. Highlights of nuclear chemistry 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-01

    In this report 9 topics of the work of the Nuclear Chemistry Group in 1995 are highlighted. A list of publications and an overview of the international cooperation is given. (orig.). 19 refs., 19 figs., 2 tabs., 2 app.

  18. LAMA Preconference and Program Highlights.

    Science.gov (United States)

    Library Administration & Management, 1988

    1988-01-01

    Highlights events of the Library Administration and Management Association 1988 conference, including presentation of awards and programs on: (1) transfer of training; (2) hiring; (3) mentoring; (4) acquisitions automation; (5) library building consultation; and (6) managing shared systems. (MES)

  19. Research and technology highlights, 1993

    Science.gov (United States)

    1994-01-01

    This report contains highlights of the major accomplishments and applications that have been made by Langley researchers and by our university and industry colleagues during the past year. The highlights illustrate both the broad range of the research and technology activities supported by NASA Langley Research Center and the contributions of this work toward maintaining United States leadership in aeronautics and space research. This report also describes some of the Center's most important research and testing facilities.

  20. Eddy Effects in the General Circulation, Spanning Mean Currents, Mesoscale Eddies, and Topographic Generation, Including Submesoscale Nests

    Science.gov (United States)

    2014-09-30

    alongshore winds favoring upwelling circulation. As for the other EBUS (e.g., Humboldt, Benguela, and Canary Currents ), equatorward winds drive...Eddy Effects in the General Circulation, Spanning Mean Currents , Mesoscale Eddies, and Topographic Generation, Including Submesoscale Nests...environments OBJECTIVES The central scientific questions are how the eddies control the persistent currents by their eddy-induced momentum and buoyancy fluxes

  1. Enhancing the capabilities of eddy current techniques for non-destructive evaluation of austenitic stainless steels

    International Nuclear Information System (INIS)

    Rao, B.P.C.; Thirunavukkarasu, S.; Sasi, B.; Jayakumar, T.; Baldev Raj

    2010-01-01

    Eddy current non-destructive evaluation (NDE) techniques find many applications during fabrication and in-service inspection of components made of stainless steel. In recent years, concurrent developments in electromagnetic field detection sensors such as giant magneto-resistive (GMR), giant-magneto impedance (GMI) and SQUIDs sensors, computers, microelectronics, and incorporating advanced signal and image processing techniques, have paved the way for enhancing the capabilities of existing eddy current (EC) techniques for examination of austenitic stainless steel (SS) plates, tubes and other geometries and several innovative methodologies have been developed. This paper highlights a few such applications in EC testing to austenitic stainless steel components used in fast reactors. (author)

  2. Eddy current testing with high penetration

    International Nuclear Information System (INIS)

    Becker, R.; Kroening, M.

    1999-01-01

    The low-frequency eddy current testing method is used when penetration into very deep layers is required. The achievable penetration depth is determined among other parameters by the lowest testing frequency that can be realised together with the eddy current sensor. When using inductive sensors, the measuring effect declines proportional to the lowering frequency (induction effect). Further reduction of testing frequency requires other types of sensors, as e.g. the GMR (Giant Magnetic Resistance), which achieves a constant measuring sensitivity down to the steady field. The multi-frequency eddy current testing method MFEC 3 of IZFP described here can be operated using three different scanning frequencies at a time. Two variants of eddy current probes are used in this case. Both have an inductive winding at their emitters, of the type of a measuring probe. The receiver end is either also an inductive winding, or a magnetic field-responsive resistance (GMR). (orig./CB) [de

  3. ECAPS - Eddy Current Approach and Proximity Satellites

    Data.gov (United States)

    National Aeronautics and Space Administration — Multiple, energized coils in a small satellite will generate eddy currents in the skin of the International Space Station (ISS). This will create repulsive forces...

  4. Observed eddy dissipation in the Agulhas Current

    CSIR Research Space (South Africa)

    Braby, L

    2016-08-01

    Full Text Available (negative) velocity anomalies propagate downstream in the Agulhas Current at 44 km/d (23 km/d). Many models are unable to represent these eddy dissipation processes, affecting our understanding of the Agulhas Current....

  5. Eddy current testing device using unbalance bridge

    International Nuclear Information System (INIS)

    Hoshikawa, H.; Koido, J.; Ishibashi, Y.

    1976-01-01

    An easily readjustable unbalance bridge has been invented and in utilizing the same, an eddy current testing equipment excellent in suppression of the lift-off effect and high in the detection sensitivity has been developed

  6. Thin film eddy current impulse deicer

    Science.gov (United States)

    Smith, Samuel O.; Zieve, Peter B.

    1990-01-01

    Two new styles of electrical impulse deicers has been developed and tested in NASA's Icing Research Tunnel. With the Eddy Current Repulsion Deicing Boot (EDB), a thin and flexible spiral coil is encapsulated between two thicknesses of elastomer. The coil, made by an industrial printed circuit board manufacturer, is bonded to the aluminum aircraft leading edge. A capacitor bank is discharged through the coil. Induced eddy currents repel the coil from the aluminum aircraft structure and shed accumulated ice. A second configuration, the Eddy Current Repulsion Deicing-Strip (EDS) uses an outer metal erosion strip fastened over the coil. Opposite flowing eddy currents repel the strip and create the impulse deicing force. The outer strip serves as a surface for the collection and shedding of ice and does not require any structural properties. The EDS is suitable for composite aircraft structures. Both systems successfully dispelled over 95 percent of the accumulated ice from airfoils over the range of the FAA icing envelope.

  7. Recognizing limitations in eddy current testing

    International Nuclear Information System (INIS)

    Van Drunen, G.; Cecco, V.S.

    1981-11-01

    This paper addresses known limitations and constraints in eddy current nondestructive testing. Incomplete appreciation for eddy current limitations is believed to have contributed to both under-utilization and misapplication of the technique. Neither situation need arise if known limitations are recognized. Some, such as the skin depth effect, are inherent to electromagnetic test methods and define the role of eddy current testing. Others can be overcome with available technology such as surface probes to find circumferential cracks in tubes and magnetic saturation of ferromagnetic alloys to eliminate permeability effects. The variables responsible for limitations in eddy current testing are discussed and where alternative approaches exist, these are presented. Areas with potential for further research and development are also identified

  8. Vertical eddy diffusion as a key mechanism for removing perfluorooctanoic acid (PFOA) from the global surface oceans

    International Nuclear Information System (INIS)

    Lohmann, Rainer; Jurado, Elena; Dijkstra, Henk A.; Dachs, Jordi

    2013-01-01

    Here we estimate the importance of vertical eddy diffusion in removing perfluorooctanoic acid (PFOA) from the surface Ocean and assess its importance as a global sink. Measured water column profiles of PFOA were reproduced by assuming that vertical eddy diffusion in a 3-layer ocean model is the sole cause for the transport of PFOA to depth. The global oceanic sink due to eddy diffusion for PFOA is high, with accumulated removal fluxes over the last 40 years of 660 t, with the Atlantic Ocean accounting for 70% of the global oceanic sink. The global oceans have removed 13% of all PFOA produced to a depth greater than 100 m via vertical eddy diffusion; an additional 4% has been removed via deep water formation. The top 100 m of the surface oceans store another 21% of all PFOA produced (∼1100 t). Highlights: •Eddy diffusion has removed ∼660 t of PFOA from surface oceans over the last 40 years. •Atlantic Ocean accounts for 70% of the global oceanic sink of PFOA. •Vertical eddy diffusion has moved ∼13% of PFOA to oceans deeper than 100 m. •Around 4% of PFOA has been removed via deep water formation. •The top 100 m of global oceans contain ∼21% of historical PFOA production. -- Vertical eddy diffusion is an important removal process for hydrophilic organic pollutants such as PFOA from the surface ocean

  9. A pivotal role for ocean eddies in the distribution of microbial communities across the Antarctic Circumpolar Current.

    Directory of Open Access Journals (Sweden)

    Siddarthan Venkatachalam

    Full Text Available Mesoscale variability and associated eddy fluxes play crucial roles in ocean circulation dynamics and the ecology of the upper ocean. In doing so, these features are biologically important, providing a mechanism for the mixing and exchange of nutrients and biota within the ocean. Transient mesoscale eddies in the Southern Ocean are known to relocate zooplankton communities across the Antarctic Circumpolar Current (ACC and are important foraging grounds for marine top predators. In this study we investigated the role of cyclonic and anti-cyclonic eddies formed at the South-West Indian Ridge on the spatial variability and diversity of microbial communities. We focused on two contrasting adjacent eddies within the Antarctic Polar Frontal Zone to determine how these features may influence the microbial communities within this region. The water masses and microbiota of the two eddies, representative of a cyclonic cold core from the Antarctic zone and an anti-cyclonic warm-core from the Subantarctic zone, were compared. The data reveal that the two eddies entrain distinct microbial communities from their points of origin that are maintained for up to ten months. Our findings highlight the ecological impact that changes, brought by the translocation of eddies across the ACC, have on microbial diversity.

  10. Eddy-current probe design

    International Nuclear Information System (INIS)

    Kincaid, T.G.; McCary, R.O.

    1983-01-01

    This paper describes theoretical and experimental work directed toward finding the optimum probe dimensions and operating frequency for eddy current detection of half-penny surface cracks in nonmagnetic conducting materials. The study applies to probes which excite an approximately uniform spatial field over the length of the crack at the surface of the material. In practical terms, this means that the probe is not smaller than the crack length in any of its critical dimensions. The optimization of a simple coil probe is first analyzed in detail. It is shown that signal-to-noise ratio and lift-off discrimination are maximized by a pancake coil with mean radius not greater than the crack length, operated at a frequency which gives a skin depth equal to the crack depth. The results obtained for the simple coil are then used as a basis for discussion of the design of coils with ferrite cores and shields, and for the design of recording head type probes

  11. Brookhaven highlights, 1986-1987

    International Nuclear Information System (INIS)

    Rowe, M.S.

    1988-01-01

    The highlights of research conducted between October 1985 and September 1987 at Brookhaven National Laboratory are reviewed in this publication. Also covered are the administrative and financial status of the laboratory and a brief mention of meetings held and honors received. (FI)

  12. DeepEddy : a simple deep architecture for mesoscale oceanic eddy detection in SAR images

    NARCIS (Netherlands)

    Huang, Dongmei; Du, Yanling; He, Qi; Song, Wei; Liotta, Antonio

    2017-01-01

    Automatic detection of mesoscale oceanic eddies is in great demand to monitor their dynamics which play a significant role in ocean current circulation and marine climate change. Traditional methods of eddies detection using remotely sensed data are usually based on physical parameters, geometrics,

  13. Study, design and manufacture eddy current probes for industry applications

    International Nuclear Information System (INIS)

    Nguyen Phuc; Nguyen Van Thuy; Vuong Binh Duong; Do Minh Duc; Trinh Dinh Truong; Tran Trong Duc; Do Tung Khanh; Dang Quang Trung

    2016-01-01

    This study is based on the studying, designing and manufacturing of eddy current probes for industry applications. The main tasks of this study include: i) Describes the overview and classification of eddy current probes (which can be classified into three categories based on the mode of operation: absolute eddy current probe, differential eddy current probe and reflect eddy current probe); ii) Describes the three methods of probe designing and manufacturing (including experimental, analytical and numerical designs); iii) Describes the designing and manufacturing of eddy current probes for industry applications, which based on experimental and analytical methods. Based on this study, we have successfully manufactured some current probes (including absolute eddy current probe, differential eddy current probe and reflect eddy current probe) for surface and tube inspections. (author)

  14. Eddies in the Red Sea: A statistical and dynamical study

    KAUST Repository

    Zhan, Peng

    2014-06-01

    Sea level anomaly (SLA) data spanning 1992–2012 were analyzed to study the statistical properties of eddies in the Red Sea. An algorithm that identifies winding angles was employed to detect 4998 eddies propagating along 938 unique eddy tracks. Statistics suggest that eddies are generated across the entire Red Sea but that they are prevalent in certain regions. A high number of eddies is found in the central basin between 18°N and 24°N. More than 87% of the detected eddies have a radius ranging from 50 to 135 km. Both the intensity and relative vorticity scale of these eddies decrease as the eddy radii increase. The averaged eddy lifespan is approximately 6 weeks. AEs and cyclonic eddies (CEs) have different deformation features, and those with stronger intensities are less deformed and more circular. Analysis of long-lived eddies suggests that they are likely to appear in the central basin with AEs tending to move northward. In addition, their eddy kinetic energy (EKE) increases gradually throughout their lifespans. The annual cycles of CEs and AEs differ, although both exhibit significant seasonal cycles of intensity with the winter and summer peaks appearing in February and August, respectively. The seasonal cycle of EKE is negatively correlated with stratification but positively correlated with vertical shear of horizontal velocity and eddy growth rate, suggesting that the generation of baroclinic instability is responsible for the activities of eddies in the Red Sea.

  15. Energy Policy. Highlights. 2013 Edition

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-07-01

    Energy Policy Highlights showcases recent developments in energy policies among all 28 IEA member countries. Each contribution underscores the changing nature of both global and domestic energy challenges, as well as the commonality of energy concerns among member countries. The policies highlighted in this publication identify an urgent need to reduce greenhouse gas (GHG) emissions as a clear policy objective. Electricity, enhancing energy efficiency and increasing the share of renewables in the energy mix in a cost effective manner are likewise areas of common focus. On the end-user side, increasing public awareness of domestic energy policies through improved transparency and engagement is an important facet of policy support among IEA member countries. The successful implementation of policies and other initiatives benefitted from efforts to inform the public.

  16. Ocean eddies and climate predictability.

    Science.gov (United States)

    Kirtman, Ben P; Perlin, Natalie; Siqueira, Leo

    2017-12-01

    A suite of coupled climate model simulations and experiments are used to examine how resolved mesoscale ocean features affect aspects of climate variability, air-sea interactions, and predictability. In combination with control simulations, experiments with the interactive ensemble coupling strategy are used to further amplify the role of the oceanic mesoscale field and the associated air-sea feedbacks and predictability. The basic intent of the interactive ensemble coupling strategy is to reduce the atmospheric noise at the air-sea interface, allowing an assessment of how noise affects the variability, and in this case, it is also used to diagnose predictability from the perspective of signal-to-noise ratios. The climate variability is assessed from the perspective of sea surface temperature (SST) variance ratios, and it is shown that, unsurprisingly, mesoscale variability significantly increases SST variance. Perhaps surprising is the fact that the presence of mesoscale ocean features even further enhances the SST variance in the interactive ensemble simulation beyond what would be expected from simple linear arguments. Changes in the air-sea coupling between simulations are assessed using pointwise convective rainfall-SST and convective rainfall-SST tendency correlations and again emphasize how the oceanic mesoscale alters the local association between convective rainfall and SST. Understanding the possible relationships between the SST-forced signal and the weather noise is critically important in climate predictability. We use the interactive ensemble simulations to diagnose this relationship, and we find that the presence of mesoscale ocean features significantly enhances this link particularly in ocean eddy rich regions. Finally, we use signal-to-noise ratios to show that the ocean mesoscale activity increases model estimated predictability in terms of convective precipitation and atmospheric upper tropospheric circulation.

  17. Highlights of nuclear chemistry 1994

    International Nuclear Information System (INIS)

    1994-12-01

    Highlights were: 1. Fission product release: benchmark calculations for severe nuclear accidents; 2. Thermochemical data for reactor materials and fission products; 3. thermochemical calculations on fuel of the high-temperature gas-cooled reactor; 4. Formation of organic tellurides during nuclear accidents?; 5. Reaction of tellurium with Zircaloy-4; 6. Transmutation of fission products; 7. The thermal conductivity of high-burnup UO 2 fuel; 8. Tritium retention in graphite. (orig./HP)

  18. Tourette syndrome research highlights 2015

    Science.gov (United States)

    Richards, Cheryl A.; Black, Kevin J.

    2016-01-01

    We present selected highlights from research that appeared during 2015 on Tourette syndrome and other tic disorders. Topics include phenomenology, comorbidities, developmental course, genetics, animal models, neuroimaging, electrophysiology, pharmacology, and treatment. We briefly summarize articles whose results we believe may lead to new treatments, additional research or modifications in current models of TS. PMID:27429744

  19. LHC Results Highlights (CLASHEP 2013)

    CERN Document Server

    Gonzalez, O.

    2015-05-22

    The good performance of the LHC provided enough data at 7 TeV and 8 TeV to allow the experiments to perform very competitive measurements and to expand the knowledge about the fundamental interaction far beyond that from previous colliders. This report summarizes the highlights of the results obtained with these data samples by the four large experiments, covering all the topics of the physics program and focusing on those exploiting the possibilities of the LHC.

  20. Eddy currents in pulsed field measurements

    International Nuclear Information System (INIS)

    Kuepferling, M.; Groessinger, R.; Wimmer, A.; Taraba, M.; Scholz, W.

    2002-01-01

    Full text: One problem of pulsed field magnetometry is an error in magnetization, which appears in measurements of conducting samples. This error is due to eddy currents induced by a time varying field. To allow predictions how eddy currents exert influence on the hysteresis loop, systematic experimental and theoretical studies of pulsed field measurements of metallic samples were performed. The theoretical studies include analytical calculations as well as numerical ones using a 2D finite element software. In the measurements three physical parameters have been varied: i) the conductivity of the sample by using two different materials, in this case technical Cu and Al ii) size and shape of the sample by using cylinders, spheres and cuboids iii) the pulse duration of the external field by changing the capacitor battery from 8mF ( =9.1ms) to 24mF ( =15.7ms). The time dependence of the external field corresponds with a pulsed damped harmonic oscillation with a maximum value of 5.2T. The samples were studied in the as cast state (after machining) as well as after heat treatment. Theoretical calculations showed not only good agreement with the absolute values of the measured eddy current m agnetization , they also gave an explanation of the shape of the eddy current hysteresis and the dependence of the eddy current 'magnetization' on parameters as pulse duration of the external field and conductivity of the sample. (author)

  1. Experimental modeling of eddy current inspection capabilities

    International Nuclear Information System (INIS)

    Junker, W.R.; Clark, W.G.

    1984-01-01

    This chapter examines the experimental modeling of eddy current inspection capabilities based upon the use of liquid mercury samples designed to represent metal components containing discontinuities. A brief summary of past work with mercury modeling and a detailed discussion of recent experiments designed to further evaluate the technique are presented. The main disadvantages of the mercury modeling concept are that mercury is toxic and must be handled carefully, liquid mercury can only be used to represent nonferromagnetic materials, and wetting and meniscus problems can distort the effective size of artificial discontinuities. Artificial discontinuities placed in a liquid mercury sample can be used to represent discontinuities in solid metallic structures. Discontinuity size and type cannot be characterized from phase angle and signal amplitude data developed with a surface scanning, pancake-type eddy current probe. It is concluded that the mercury model approach can greatly enhance the overall understanding and applicability of eddy current inspection techniques

  2. Turbulent fluxes by "Conditional Eddy Sampling"

    Science.gov (United States)

    Siebicke, Lukas

    2015-04-01

    Turbulent flux measurements are key to understanding ecosystem scale energy and matter exchange, including atmospheric trace gases. While the eddy covariance approach has evolved as an invaluable tool to quantify fluxes of e.g. CO2 and H2O continuously, it is limited to very few atmospheric constituents for which sufficiently fast analyzers exist. High instrument cost, lack of field-readiness or high power consumption (e.g. many recent laser-based systems requiring strong vacuum) further impair application to other tracers. Alternative micrometeorological approaches such as conditional sampling might overcome major limitations. Although the idea of eddy accumulation has already been proposed by Desjardin in 1972 (Desjardin, 1977), at the time it could not be realized for trace gases. Major simplifications by Businger and Oncley (1990) lead to it's widespread application as 'Relaxed Eddy Accumulation' (REA). However, those simplifications (flux gradient similarity with constant flow rate sampling irrespective of vertical wind velocity and introduction of a deadband around zero vertical wind velocity) have degraded eddy accumulation to an indirect method, introducing issues of scalar similarity and often lack of suitable scalar flux proxies. Here we present a real implementation of a true eddy accumulation system according to the original concept. Key to our approach, which we call 'Conditional Eddy Sampling' (CES), is the mathematical formulation of conditional sampling in it's true form of a direct eddy flux measurement paired with a performant real implementation. Dedicated hardware controlled by near-real-time software allows full signal recovery at 10 or 20 Hz, very fast valve switching, instant vertical wind velocity proportional flow rate control, virtually no deadband and adaptive power management. Demonstrated system performance often exceeds requirements for flux measurements by orders of magnitude. The system's exceptionally low power consumption is ideal

  3. Solitonlike solutions in loop current eddies

    Science.gov (United States)

    Nakamoto, Shoichiro

    1989-01-01

    The application of the nonlinear quasi-geostrophic equations to an isolated eddy in the western continental slope region in the Gulf of Mexico is examined for a two-layer ocean model with bottom topography. In the linear limit, solutions are topographic nondispersive waves. Form-preserving solutions, or solitons, have been found. The solution is shown to be a limiting form for a nonlinear dispersive system propagating northward along the topographic waveguide in the western continental slope region in the Gulf of Mexico. Using satellite-tracked drifter data, a linear relationship is found between the amplitude of the deduced stream function of the eddy and its observed translational velocity over the continental slope, which supports the hypothesis that some mesoscale eddies interacting with the continental slope behave as solitons.

  4. Lateral resolution of eddy current imaging

    International Nuclear Information System (INIS)

    Hassan, W.; Blodgett, M.; Nagy, P.B.

    2002-01-01

    Analytical, finite element simulation, and experimental methods were used to investigate the lateral resolution of eddy current microscopy. It was found that the lateral resolution of eddy current imaging is ultimately limited by the probe-coil geometry and dimensions, but both the inspection frequency and the phase angle can be used to optimize the resolution, to some degree, at the expense of sensitivity. Electric anisotropy exhibited by noncubic crystallographic classes of materials such as titanium alloys can play a very similar role in electromagnetic materials characterization of polycrystalline metals to that of elastic anisotropy in ultrasonic materials characterization. Our results demonstrate that eddy current microscopy can be enhanced via a high-resolution, small diameter probe-coil which delivers a unique materials characterization tool well suited for the evaluation of Ti alloys

  5. Eddy current techniques for super duplex stainless steel characterization

    International Nuclear Information System (INIS)

    Camerini, C.; Sacramento, R.; Areiza, M.C.; Rocha, A.; Santos, R.; Rebello, J.M.; Pereira, G.

    2015-01-01

    Super duplex stainless steel (SDSS) is a two-phase material where the microstructure consists of grains of ferrite (δ) and austenite (γ). SDSS exhibit an attractive combination of properties, such as: strength, toughness and stress corrosion cracking resistance. Nevertheless, SDSS attain these properties after a controlled solution heat treatment, leading to a similar volumetric fraction of δ and γ. Any further heat treatment, welding operation for example, can change the balance of the original phases, or may also lead to precipitation of a deleterious phase, such as sigma (σ). For these situations, the material corrosion resistance is severely impaired. In the present study, several SDSS samples with low σ phase content and non-balanced microstructure were intentionally obtained by thermally treating SDSS specimens. Electromagnetic techniques, conventional Eddy Current Testing (ECT) and Saturated Low Frequency Eddy Current (SLOFEC), were employed to characterize the SDSS samples. The results showed that ECT and SLOFEC are reliable techniques to evaluate σ phase presence in SDSS and can provide an estimation of the δ content. - Highlights: • Sigma phase precipitation, even for low amounts, dramatically affects SDSS properties. • SDSS samples were thermally treated and carefully characterized by X-Ray Diffraction. • NDT techniques detected low amounts of sigma phase in SDSS microstructure

  6. Eddy current techniques for super duplex stainless steel characterization

    Energy Technology Data Exchange (ETDEWEB)

    Camerini, C., E-mail: cgcamerini@metalmat.ufrj.br [Laboratory of Non-Destructive Testing, Corrosion and Welding, Department of Metallurgical and Materials Engineering, Federal University of Rio de Janeiro (Brazil); Sacramento, R.; Areiza, M.C.; Rocha, A. [Laboratory of Non-Destructive Testing, Corrosion and Welding, Department of Metallurgical and Materials Engineering, Federal University of Rio de Janeiro (Brazil); Santos, R. [PETROBRAS R& D Center, Rio de Janeiro (Brazil); Rebello, J.M.; Pereira, G. [Laboratory of Non-Destructive Testing, Corrosion and Welding, Department of Metallurgical and Materials Engineering, Federal University of Rio de Janeiro (Brazil)

    2015-08-15

    Super duplex stainless steel (SDSS) is a two-phase material where the microstructure consists of grains of ferrite (δ) and austenite (γ). SDSS exhibit an attractive combination of properties, such as: strength, toughness and stress corrosion cracking resistance. Nevertheless, SDSS attain these properties after a controlled solution heat treatment, leading to a similar volumetric fraction of δ and γ. Any further heat treatment, welding operation for example, can change the balance of the original phases, or may also lead to precipitation of a deleterious phase, such as sigma (σ). For these situations, the material corrosion resistance is severely impaired. In the present study, several SDSS samples with low σ phase content and non-balanced microstructure were intentionally obtained by thermally treating SDSS specimens. Electromagnetic techniques, conventional Eddy Current Testing (ECT) and Saturated Low Frequency Eddy Current (SLOFEC), were employed to characterize the SDSS samples. The results showed that ECT and SLOFEC are reliable techniques to evaluate σ phase presence in SDSS and can provide an estimation of the δ content. - Highlights: • Sigma phase precipitation, even for low amounts, dramatically affects SDSS properties. • SDSS samples were thermally treated and carefully characterized by X-Ray Diffraction. • NDT techniques detected low amounts of sigma phase in SDSS microstructure.

  7. Transmit-receive eddy current probes

    International Nuclear Information System (INIS)

    Obrutsky, L.S.; Sullivan, S.P.; Cecco, V.S.

    1997-01-01

    In the last two decades, due to increased inspection demands, eddy current instrumentation has advanced from single-frequency, single-output instruments to multifrequency, computer-aided systems. This has significantly increased the scope of eddy current testing, but, unfortunately, it has also increased the cost and complexity of inspections. In addition, this approach has not always improved defect detectability or signal-to-noise. Most eddy current testing applications are still performed with impedance probes, which have well known limitations. However, recent research at AECL has led to improved eddy current inspections through the design and development of transmit-receive (T/R) probes. T/R eddy current probes, with laterally displaced transmit and receive coils, present a number of advantages over impedance probes. They have improved signal-to-noise ratio in the presence of variable lift-off compared to impedance probes. They have strong directional properties, permitting probe optimization for circumferential or axial crack detection, and possess good phase discrimination to surface defects. They can significantly increase the scope of eddy current testing permitting reliable detection and sizing of cracks in heat exchanger tubing as well as in welded areas of both ferritic and non-ferromagnetic components. This presentation will describe the operating principles of T/R probes with the help of computer-derived normalized voltage diagrams. We will discuss their directional properties and analyze the advantages of using single and multiple T/R probes over impedance probes for specific inspection cases. Current applications to surface and tube testing and some typical inspection results will be described. (author)

  8. MASCOTTE: analytical model of eddy current signals

    International Nuclear Information System (INIS)

    Delsarte, G.; Levy, R.

    1992-01-01

    Tube examination is a major application of the eddy current technique in the nuclear and petrochemical industries. Such examination configurations being specially adapted to analytical modes, a physical model is developed on portable computers. It includes simple approximations made possible by the effective conditions of the examinations. The eddy current signal is described by an analytical formulation that takes into account the tube dimensions, the sensor conception, the physical characteristics of the defect and the examination parameters. Moreover, the model makes it possible to associate real signals and simulated signals

  9. Casimir Interaction from Magnetically Coupled Eddy Currents

    Science.gov (United States)

    Intravaia, Francesco; Henkel, Carsten

    2009-09-01

    We study the quantum and thermal fluctuations of eddy (Foucault) currents in thick metallic plates. A Casimir interaction between two plates arises from the coupling via quasistatic magnetic fields. As a function of distance, the relevant eddy current modes cross over from a quantum to a thermal regime. These modes alone reproduce previously discussed thermal anomalies of the electromagnetic Casimir interaction between good conductors. In particular, they provide a physical picture for the Casimir entropy whose nonzero value at zero temperature arises from a correlated, glassy state.

  10. About Eddy Currents in Induction Melting Processes

    Directory of Open Access Journals (Sweden)

    Gafiţa Nicolae-Bogdan

    2008-05-01

    Full Text Available In this paper we present a method forcomputing the eddy currents in induction meltingprocesses for non-ferrous alloys. We take intoconsideration the situation when only the crucible ismoving, inside the coils. This fact makes differentialcomputation methods to be hard to apply, because isnecessary to generate a new mesh and a new systemmatrix for every for every new position of the cruciblerelated to the coils. Integral methods cancel thisdrawback because the mesh is generated only for thedomains with eddy currents. For integral methods, themesh and the inductance matrix remain unchangedduring the movement of the crucible; only the free termsof the equation system will change.

  11. Eddy Correlation Flux Measurement System (ECOR) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Cook, DR

    2011-01-31

    The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration.

  12. Eddy current standards - Cracks versus notches

    Science.gov (United States)

    Hagemaier, D. J.; Collingwood, M. R.; Nguyen, K. H.

    1992-10-01

    Eddy current tests aimed at evaluating cracks and electron-discharge machined (EDM) notches in 7075-T6 aluminum specimens are described. A comparison of the shape and amplitude of recordings made from both transverse and longitudinal scans of small EDM notches and fatigue cracks showd almost identical results. The signal amplitude and phase angle increased with an increase of EDM notch and crak size. It is concluded that equivalent eddy current results obtained from similar-size surface cracks and notches in aluminum can be used to establish a desired sensitivity level for inspection.

  13. Eddy current inspection of mildly ferromagnetic tubing

    International Nuclear Information System (INIS)

    Mayo, W.R.; Carter, J.R.

    1984-02-01

    The past decade has seen the development of eddy current probes for inspection of the mildly ferro-magnetic alloy Monel 400. Due to the rapid advances in permanent magnet technology similar probes have been upgraded to magnetically saturate, and hence inspect, the duplex stainless steel Sandvik 3RE60, which has saturation induction more than twice that of Monel 400. Prototypes of these probes have been tested in three ways: saturation capability, quality of typical eddy current data, and ability to eliminate permeability induced signals. Successful laboratory testing, potential applications, and limitations of these type probes are discussed

  14. The eddy kinetic energy budget in the Red Sea

    KAUST Repository

    Zhan, Peng; Subramanian, Aneesh C.; Yao, Fengchao; Kartadikaria, Aditya R.; Guo, Daquan; Hoteit, Ibrahim

    2016-01-01

    The budget of eddy kinetic energy (EKE) in the Red Sea, including the sources, redistributions and sink, is examined using a high-resolution eddy-resolving ocean circulation model. A pronounced seasonally varying EKE is identified, with its maximum

  15. Visualization and analysis of eddies in a global ocean simulation

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Sean J [Los Alamos National Laboratory; Hecht, Matthew W [Los Alamos National Laboratory; Petersen, Mark [Los Alamos National Laboratory; Strelitz, Richard [Los Alamos National Laboratory; Maltrud, Mathew E [Los Alamos National Laboratory; Ahrens, James P [Los Alamos National Laboratory; Hlawitschka, Mario [UC DAVIS; Hamann, Bernd [UC DAVIS

    2010-10-15

    Eddies at a scale of approximately one hundred kilometers have been shown to be surprisingly important to understanding large-scale transport of heat and nutrients in the ocean. Due to difficulties in observing the ocean directly, the behavior of eddies below the surface is not very well understood. To fill this gap, we employ a high-resolution simulation of the ocean developed at Los Alamos National Laboratory. Using large-scale parallel visualization and analysis tools, we produce three-dimensional images of ocean eddies, and also generate a census of eddy distribution and shape averaged over multiple simulation time steps, resulting in a world map of eddy characteristics. As expected from observational studies, our census reveals a higher concentration of eddies at the mid-latitudes than the equator. Our analysis further shows that mid-latitude eddies are thicker, within a range of 1000-2000m, while equatorial eddies are less than 100m thick.

  16. Eddies in the Red Sea: A statistical and dynamical study

    KAUST Repository

    Zhan, Peng; Subramanian, Aneesh C.; Yao, Fengchao; Hoteit, Ibrahim

    2014-01-01

    correlated with stratification but positively correlated with vertical shear of horizontal velocity and eddy growth rate, suggesting that the generation of baroclinic instability is responsible for the activities of eddies in the Red Sea.

  17. Atmospheric Research 2012 Technical Highlights

    Science.gov (United States)

    Lau, William K -M.

    2013-01-01

    This annual report, as before, is intended for a broad audience. Our readers include colleagues within NASA, scientists outside the Agency, science graduate students, and members of the general public. Inside are descriptions of atmospheric research science highlights and summaries of our education and outreach accomplishments for calendar year 2012.The report covers research activities from the Mesoscale Atmospheric Processes Laboratory, the Climate and Radiation Laboratory, the Atmospheric Chemistry and Dynamics Laboratory, and the Wallops Field Support Office under the Office of Deputy Director for Atmospheres, Earth Sciences Division in the Sciences and Exploration Directorate of NASAs Goddard Space Flight Center. The overall mission of the office is advancing knowledge and understanding of the Earths atmosphere. Satellite missions, field campaigns, peer-reviewed publications, and successful proposals are essential to our continuing research.

  18. Tools and Methods for Visualization of Mesoscale Ocean Eddies

    Science.gov (United States)

    Bemis, K. G.; Liu, L.; Silver, D.; Kang, D.; Curchitser, E.

    2017-12-01

    Mesoscale ocean eddies form in the Gulf Stream and transport heat and nutrients across the ocean basin. The internal structure of these three-dimensional eddies and the kinematics with which they move are critical to a full understanding of their transport capacity. A series of visualization tools have been developed to extract, characterize, and track ocean eddies from 3D modeling results, to visually show the ocean eddy story by applying various illustrative visualization techniques, and to interactively view results stored on a server from a conventional browser. In this work, we apply a feature-based method to track instances of ocean eddies through the time steps of a high-resolution multidecadal regional ocean model and generate a series of eddy paths which reflect the life cycle of individual eddy instances. The basic method uses the Okubu-Weiss parameter to define eddy cores but could be adapted to alternative specifications of an eddy. Stored results include pixel-lists for each eddy instance, tracking metadata for eddy paths, and physical and geometric properties. In the simplest view, isosurfaces are used to display eddies along an eddy path. Individual eddies can then be selected and viewed independently or an eddy path can be viewed in the context of all eddy paths (longer than a specified duration) and the ocean basin. To tell the story of mesoscale ocean eddies, we combined illustrative visualization techniques, including visual effectiveness enhancement, focus+context, and smart visibility, with the extracted volume features to explore eddy characteristics at multiple scales from ocean basin to individual eddy. An evaluation by domain experts indicates that combining our feature-based techniques with illustrative visualization techniques provides an insight into the role eddies play in ocean circulation. A web-based GUI is under development to facilitate easy viewing of stored results. The GUI provides the user control to choose amongst available

  19. Low eddy loss axial hybrid magnetic bearing with gimballing control ability for momentum flywheel

    International Nuclear Information System (INIS)

    Tang, Jiqiang; Sun, Jinji; Fang, Jiancheng; Shuzhi Sam, Ge

    2013-01-01

    For a magnetically suspended momentum flywheel (MSMF), the spinning rotor can be tilted by a pair of the presented axial hybrid magnetic bearing (AHMB) with eight poles and rotates around the radial axes to generate a large torque to maneuver the spacecraft. To improve the control performance and gimballing control ability of the AHMB, characteristics such as magnetic suspension force, angular stiffness and tilting momentum are researched. These segmented stator poles cause the magnetic density in the thrust rotor plate to be uneven unavoidably and the rotational loss is large at high speed, but we optimized the stator poles configuration and caused the thrust rotor plate formed by bulk DT4C and laminated material to make the magnetic density in the thrust rotor plate change less and be smoother. Laminated material such as 1J50 film with a thickness of 0.1 mm can make the variation of the magnetic density in DT4C become very small and the eddy loss of it be negligible, but the stress produced in the “O” shape stacks by reeling has a bad effect on its power loss. Nanocrystalline can reduce eddy losses and is not affected by the reeling process. Based on the AHBM consisting of the stator with eight improved poles and the presented thrust rotor plate with DT4 and nanocrystalline, the rotational loss of 5-DOF magnetically suspended momentum flywheel with angular momentum of 15 N m s at 5000 rpm has reduced from 23.4 W to 3.2 W, which proved that this AHMB has low eddy loss for the gimballing control ability. - Highlights: ► Control methods of rotor driven by AHMBs and their characteristics are researched. ► Optimized stator and rotor of AHMB reduce its eddy losses greatly. ► Presented the factors affecting the eddy losses of AHMBs. ► The good performances of AHMB with low eddy loss are proved by experiments.

  20. 76 FR 59394 - Big Eddy-Knight Transmission Project

    Science.gov (United States)

    2011-09-26

    ... DEPARTMENT OF ENERGY Bonneville Power Administration Big Eddy-Knight Transmission Project AGENCY... Eddy-Knight Transmission Project in Wasco County, Oregon and Klickitat County, Washington. Construction of the Big Eddy-Knight Transmission Project will accommodate long-term firm transmission requests...

  1. Eddy properties in the Southern California Current System

    Science.gov (United States)

    Chenillat, Fanny; Franks, Peter J. S.; Capet, Xavier; Rivière, Pascal; Grima, Nicolas; Blanke, Bruno; Combes, Vincent

    2018-05-01

    The California Current System (CCS) is an eastern boundary upwelling system characterized by strong eddies that are often generated at the coast. These eddies contribute to intense, long-distance cross-shelf transport of upwelled water with enhanced biological activity. However, the mechanisms of formation of such coastal eddies, and more importantly their capacity to trap and transport tracers, are poorly understood. Their unpredictability and strong dynamics leave us with an incomplete picture of the physical and biological processes at work, their effects on coastal export, lateral water exchange among eddies and their surrounding waters, and how long and how far these eddies remain coherent structures. Focusing our analysis on the southern part of the CCS, we find a predominance of cyclonic eddies, with a 25-km radius and a SSH amplitude of 6 cm. They are formed near shore and travel slightly northwest offshore for 190 days at 2 km day-1. We then study one particular, representative cyclonic eddy using a combined Lagrangian and Eulerian numerical approach to characterize its kinematics. Formed near shore, this eddy trapped a core made up of 67% California Current waters and 33% California Undercurrent waters. This core was surrounded by other waters while the eddy detached from the coast, leaving the oldest waters at the eddy's core and the younger waters toward the edge. The eddy traveled several months as a coherent structure, with only limited lateral exchange within the eddy.

  2. Highlights of DAMA/LIBRA

    Directory of Open Access Journals (Sweden)

    Bernabei R.

    2016-01-01

    Full Text Available The DAMA project develops and uses new/improved low background scintillation detectors to investigate the Dark Matter (DM particle component(s in the galactic halo and rare processes deep underground at the Gran Sasso National Laboratory (LNGS of the I.N.F.N.. Here some highlights of DAMA/LIBRA (Large sodium Iodide Bulk for Rare processes as a unique apparatus in direct DM investigation for its full sensitive mass, target material, intrinsic radio-purity, methodological approach and all the controls performed on the experimental parameters are outlined. The DAMA/LIBRA–phase1 and the former DAMA/NaI data (cumulative exposure 1.33 ton × yr, corresponding to 14 annual cycles have reached a model-independent evidence at 9.3 σ C.L. for the presence of DM particles in the galactic halo exploiting the DM annual modulation signature with highly radio-pure NaI(Tl target. Some of the perspectives of the presently running DAMA/LIBRA–phase2 are summarised and the powerful tools offered by a model independent strategy of DM investigation are pointed out.

  3. ESO PR Highlights in 2000

    Science.gov (United States)

    2001-01-01

    At the beginning of the new millennium, ESO and its staff are facing the future with confidence. The four 8.2-m Unit Telescopes of the Very Large Telescope (VLT) are in great shape and the VLT Interferometer (VLTI) will soon have "first fringes". The intercontinental ALMA project is progressing well and concepts for extremely large optical/infrared telescopes are being studied. They can also look back at a fruitful and rewarding past year. Perhaps the most important, single development has been the rapid transition of the Very Large Telescope (VLT). From being a "high-tech project under construction" it has now become a highly proficient, world-class astronomical observatory. This trend is clearly reflected in ESO's Press Releases , as more and more front-line scientific results emerge from rich data obtained at this very efficient facility. There were also exciting news from several of the instruments at La Silla. At the same time, the ESO community may soon grow, as steps towards membership are being taken by various European countries. Throughout 2000, a total of 54 PR communications were made, with a large number of Press Photos and Video Clips, cf. the 2000 PR Index. Some of the ESO PR highlights may be accessed directly via the clickable image on the present page. ESO PR Photo 01/01 is also available in a larger (non-clickable) version [ JPEG: 566 x 566 pix - 112k]. It may be reproduced, if credit is given to the European Southern Observatory.

  4. Large Eddy Simulation of Cryogenic Injection Processes at Supercritical Pressure

    Science.gov (United States)

    Oefelein, Joseph C.

    2002-01-01

    This paper highlights results from the first of a series of hierarchical simulations aimed at assessing the modeling requirements for application of the large eddy simulation technique to cryogenic injection and combustion processes in liquid rocket engines. The focus is on liquid-oxygen-hydrogen coaxial injectors at a condition where the liquid-oxygen is injected at a subcritical temperature into a supercritical environment. For this situation a diffusion dominated mode of combustion occurs in the presence of exceedingly large thermophysical property gradients. Though continuous, these gradients approach the behavior of a contact discontinuity. Significant real gas effects and transport anomalies coexist locally in colder regions of the flow, with ideal gas and transport characteristics occurring within the flame zone. The current focal point is on the interfacial region between the liquid-oxygen core and the coaxial hydrogen jet where the flame anchors itself.

  5. Cycloidal meandering of a mesoscale anticyclonic eddy

    Science.gov (United States)

    Kizner, Ziv; Shteinbuch-Fridman, Biana; Makarov, Viacheslav; Rabinovich, Michael

    2017-08-01

    By applying a theoretical approach, we propose a hypothetical scenario that might explain some features of the movement of a long-lived mesoscale anticyclone observed during 1990 in the Bay of Biscay [R. D. Pingree and B. Le Cann, "Three anticyclonic slope water oceanic eddies (SWODDIES) in the southern Bay of Biscay in 1990," Deep-Sea Res., Part A 39, 1147 (1992)]. In the remote-sensing infrared images, at the initial stage of observations, the anticyclone was accompanied by two cyclonic eddies, so the entire structure appeared as a tripole. However, at later stages, only the anticyclone was seen in the images, traveling generally west. Unusual for an individual eddy were the high speed of its motion (relative to the expected planetary beta-drift) and the presence of almost cycloidal meanders in its trajectory. Although surface satellites seem to have quickly disappeared, we hypothesize that subsurface satellites continued to exist, and the coherence of the three vortices persisted for a long time. A significant perturbation of the central symmetry in the mutual arrangement of three eddies constituting a tripole can make reasonably fast cycloidal drift possible. This hypothesis is tested with two-layer contour-dynamics f-plane simulations and with finite-difference beta-plane simulations. In the latter case, the interplay of the planetary beta-effect and that due to the sloping bottom is considered.

  6. A probe for Eddy current inspection devices

    International Nuclear Information System (INIS)

    1974-01-01

    The invention relates to a surface probe for Eddy current inspection devices. According to the invention, said probe comprises two magnetic core windings, with their axes in parallel relationship and at right angles to the surface of the part to be inspected. This can be applied to the nondestructive inspection of reactor components [fr

  7. Eddy current testing of heat exchangers tubes

    International Nuclear Information System (INIS)

    Gouez, J.F.; Rieusset, A.; Groix, F.

    An automatic system for Eddy Current testing of heat exchangers tubes of warships was developed. The advantages are an exposure of the controller limited at the time required to put in place the system and a reduced time of control [fr

  8. Wind changes above warm Agulhas Current eddies

    CSIR Research Space (South Africa)

    Roualt, M

    2016-10-01

    Full Text Available Sea-surface temperature (SST), altimetry derived sea-level anomalies (SLA) and surface current are used south of the Agulhas Current to identify warm core mesoscale ocean eddies presenting a distinct SST perturbation superior to 1(supo...

  9. Oceanic eddies in synthetic aperture radar images

    Indian Academy of Sciences (India)

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

    2000) can be carried out in two different ways. The first one is ..... mushroom-like currents forming composite multi- .... eddies. Combination of SAR, IR and color data will ... Fu L-L and Holt B 1982 Seasat views oceans and sea ice with.

  10. Detached Eddy Simulations of Hypersonic Transition

    Science.gov (United States)

    Yoon, S.; Barnhardt, M.; Candler, G.

    2010-01-01

    This slide presentation reviews the use of Detached Eddy Simulation (DES) of hypersonic transistion. The objective of the study was to investigate the feasibility of using CFD in general, DES in particular, for prediction of roughness-induced boundary layer transition to turbulence and the resulting increase in heat transfer.

  11. Regularization modeling for large-eddy simulation

    NARCIS (Netherlands)

    Geurts, Bernardus J.; Holm, D.D.

    2003-01-01

    A new modeling approach for large-eddy simulation (LES) is obtained by combining a "regularization principle" with an explicit filter and its inversion. This regularization approach allows a systematic derivation of the implied subgrid model, which resolves the closure problem. The central role of

  12. Large Eddy Simulations using oodlesDST

    Science.gov (United States)

    2016-01-01

    Research Agency DST-Group-TR-3205 ABSTRACT The oodlesDST code is based on OpenFOAM software and performs Large Eddy Simulations of......maritime platforms using a variety of simulation techniques. He is currently using OpenFOAM software to perform both Reynolds Averaged Navier-Stokes

  13. IEDA [Intelligent Eddy Current Data Analysis] helps make sense of eddy current data [steam generators

    International Nuclear Information System (INIS)

    Clark, R.

    1989-01-01

    The increasing sophistication of eddy current signal interpretation in steam generator tubing has improved capabilities, but has also made the process of analysis more complex and time consuming. Westinghouse has developed an intelligent computerised tool - the IEDA (Intelligent Eddy Current Data Analysis) system, to lighten the load on analysts. Since 1985, 44 plants have been inspected with IEDA, representing over 400,000 tubes. The system has provided a repeatability and a consistency not achieved by human operators. (U.K.)

  14. Cassini's Grand Finale Science Highlights

    Science.gov (United States)

    Spilker, Linda

    2017-10-01

    After 13 years in orbit, the Cassini-Huygens Mission to Saturn ended in a science-rich blaze of glory. Cassini returned its final bits of unique science data on September 15, 2017, as it plunged into Saturn's atmosphere satisfying planetary protection requirements. Cassini's Grand Finale covered a period of roughly five months and ended with the first time exploration of the region between the rings and planet.The final close flyby of Titan in late April 2017 propelled Cassini across Saturn’s main rings and into its Grand Finale orbits; 22 orbits that repeatedly dove between Saturn’s innermost rings and upper atmosphere making Cassini the first spacecraft to explore this region. The last orbit turned the spacecraft into the first Saturn upper atmospheric probe.The Grand Finale orbits provided highest resolution observations of both the rings and Saturn, and in-situ sampling of the ring particle composition, Saturn's atmosphere, plasma, and innermost radiation belts. The gravitational field was measured to unprecedented accuracy, providing information on the interior structure of the planet, winds in the deeper atmosphere, and mass of the rings. The magnetic field provided insight into the physical nature of the magnetic dynamo and structure of the internal magnetic field. The ion and neutral mass spectrometer sampled the upper atmosphere for molecules that escape the atmosphere in addition to molecules originating from the rings. The cosmic dust analyzer directly sampled the composition from different parts of the main rings for the first time. Fields and particles instruments directly measured the plasma environment between the rings and planet.Science highlights and new mysteries gleaned to date from the Grand Finale orbits will be discussed.The research described in this paper was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Copyright 2017

  15. Mesoscale Eddies in the Northwestern Pacific Ocean: Three-Dimensional Eddy Structures and Heat/Salt Transports

    Science.gov (United States)

    Dong, Di; Brandt, Peter; Chang, Ping; Schütte, Florian; Yang, Xiaofeng; Yan, Jinhui; Zeng, Jisheng

    2017-12-01

    The region encompassing the Kuroshio Extension (KE) in the Northwestern Pacific Ocean (25°N-45°N and 130°E-180°E) is one of the most eddy-energetic regions of the global ocean. The three-dimensional structures and transports of mesoscale eddies in this region are comprehensively investigated by combined use of satellite data and Argo profiles. With the allocation of Argo profiles inside detected eddies, the spatial variations of structures of eddy temperature and salinity anomalies are analyzed. The results show that eddies predominantly have subsurface (near-surface) intensified temperature and salinity anomalies south (north) of the KE jet, which is related to different background stratifications between these regions. A new method based on eddy trajectories and the inferred three-dimensional eddy structures is proposed to estimate heat and salt transports by eddy movements in a Lagrangian framework. Spatial distributions of eddy transports are presented over the vicinity of the KE for the first time. The magnitude of eddy-induced meridional heat (freshwater volume) transport is on the order of 0.01 PW (103 m3/s). The eddy heat transport divergence results in an oceanic heat loss south and heat gain north of the KE, thereby reinforcing and counteracting the oceanic heat loss from air-sea fluxes south and north of the KE jet, respectively. It also suggests a poleward heat transport across the KE jet due to eddy propagation.

  16. Wind Forced Variability in Eddy Formation, Eddy Shedding, and the Separation of the East Australian Current

    Science.gov (United States)

    Bull, Christopher Y. S.; Kiss, Andrew E.; Jourdain, Nicolas C.; England, Matthew H.; van Sebille, Erik

    2017-12-01

    The East Australian Current (EAC), like many other subtropical western boundary currents, is believed to be penetrating further poleward in recent decades. Previous observational and model studies have used steady state dynamics to relate changes in the westerly winds to changes in the separation behavior of the EAC. As yet, little work has been undertaken on the impact of forcing variability on the EAC and Tasman Sea circulation. Here using an eddy-permitting regional ocean model, we present a suite of simulations forced by the same time-mean fields, but with different atmospheric and remote ocean variability. These eddy-permitting results demonstrate the nonlinear response of the EAC to variable, nonstationary inhomogeneous forcing. These simulations show an EAC with high intrinsic variability and stochastic eddy shedding. We show that wind stress variability on time scales shorter than 56 days leads to increases in eddy shedding rates and southward eddy propagation, producing an increased transport and southward reach of the mean EAC extension. We adopt an energetics framework that shows the EAC extension changes to be coincident with an increase in offshore, upstream eddy variance (via increased barotropic instability) and increase in subsurface mean kinetic energy along the length of the EAC. The response of EAC separation to regional variable wind stress has important implications for both past and future climate change studies.

  17. Obituary: John Allen Eddy (1931-2009)

    Science.gov (United States)

    Gingerich, Owen

    2011-12-01

    Jack Eddy, who was born 25 March 1931 in Pawnee City in southeastern Nebraska, died after a long battle with cancer in Tucson, Arizona, on 10 June 2009. Best known for his work on the long-term instability of the sun, described in a landmark paper in Science titled "The Maunder Minimum," he also deserves recognition as one of the triumvirate who founded the Historical Astronomy Division of the AAS. His father ran a cooperative farm store where Jack worked as a teenager; his parents were of modest means and there were concerns whether he could afford college, but one of the state senators, also from Pawnee City, nominated him for the U.S. Naval Academy. A course in celestial navigation gave him a love of the sky. After graduation in 1953, he served four years on aircraft carriers in the Pacific during the Korean War and then as a navigator and operations officer on a destroyer in the Persian Gulf. In 1957, he left the Navy and entered graduate school at the University of Colorado in Boulder, where in 1962 he received a Ph.D. in astro-geophysics. His thesis, supervised by Gordon Newkirk, dealt with light scattering in the upper atmosphere, based on data from stratospheric balloon flights. He then worked as teacher and researcher at the High Altitude Observatory in Boulder. Always adventuresome and willing to explore new frontiers, on his own time Eddy examined an Amerindian stone circle in the Big Horn mountains of Wyoming, a so-called medicine wheel, concluding that there were alignments with both the solstitial sun and Aldebaran. His conjectures became a cover story on Science magazine in June of 1974. In 1971 Jack privately reproduced for his friends a small collection of his own hilarious cartoons titled "Job Opportunities for Out-of-work Astronomers," with an abstract beginning, "Contrary to popular belief, a PhD in Astronomy/Astrophysics need not be a drawback in locating work in this decade." For example, under merchandising, a used car salesman advertises

  18. Eddy-induced salinity pattern in the North Pacific

    Science.gov (United States)

    Abe, H.; Ebuchi, N.; Ueno, H.; Ishiyama, H.; Matsumura, Y.

    2017-12-01

    This research examines spatio-temporal behavior of sea surface salinity (SSS) after intense rainfall events using observed data from Aquarius. Aquarius SSS in the North Pacific reveals one notable event in which SSS is locally freshened by intense rainfall. Although SSS pattern shortly after the rainfall reflects atmospheric pattern, its final form reflects ocean dynamic structure; an anticyclonic eddy. Since this anticyclonic eddy was located at SSS front created by precipitation, this eddy stirs the water in a clockwise direction. This eddy stirring was visible for several months. It is expected horizontal transport by mesoscale eddies would play significant role in determining upper ocean salinity structure.

  19. Zonal Detached-Eddy Simulation of Turbulent Unsteady Flow over Iced Airfoils

    KAUST Repository

    Zhang, Yue

    2015-07-23

    This paper presentsamultiscale finite-element formulation for the second modeofzonal detached-eddy simulation. The multiscale formulation corrects the lack of stability of the standard Galerkin formulation by incorporating the effect of unresolved scales to the grid (resolved) scales. The stabilization terms arise naturally and are free of userdefined stability parameters. Validation of the method is accomplished via the turbulent flow over tandem cylinders. The boundary-layer separation, free shear-layer rollup, vortex shedding from the upstream cylinder, and interaction with the downstream cylinder are well reproduced. Good agreement with experimental measurements gives credence to the accuracy of zonal detached-eddy simulation in modeling turbulent separated flows. A comprehensive study is then conducted on the performance degradation of ice-contaminated airfoils. NACA 23012 airfoil with a spanwise ice ridge and Gates Learjet Corporation-305 airfoil with a leading-edge horn-shape glaze ice are selected for investigation. Appropriate spanwise domain size and sufficient grid density are determined to enhance the reliability of the simulations. A comparison of lift coefficient and flowfield variables demonstrates the added advantage that the zonal detached-eddy simulation model brings to the Spalart-Allmaras turbulence model. Spectral analysis and instantaneous visualization of turbulent structures are also highlighted via zonal detached-eddy simulation. Copyright © 2015 by the CFD Lab of McGill University. Published by the American Institute of Aeronautics and Astronautics, Inc.

  20. Atmospheric Research 2014 Technical Highlights

    Science.gov (United States)

    Platnick, Steven

    2015-01-01

    Earth Sciences Division in atmospheric science research. Figure 1.1 shows the 20-year record of peer-reviewed publications and proposals among the various Laboratories. This data shows that the scientific work being conducted in the Laboratories is competitive with the work being done elsewhere in universities and other government agencies. The office of Deputy Director for Atmospheric Research will strive to maintain this record by rigorously monitoring and promoting quality while emphasizing coordination and integration among atmospheric disciplines. Also, an appropriate balance will be maintained between the scientists' responsibility for large collaborative projects and missions and their need to carry out active science research as a principal investigator. This balance allows members of the Laboratories to improve their scientific credentials, and develop leadership potentials. Interdisciplinary research is carried out in collaboration with other laboratories and research groups within the Earth Sciences Division, across the Sciences and Exploration Directorate, and with partners in universities and other government agencies. Members of the Laboratories interact with the general public to support a wide range of interests in the atmospheric sciences. Among other activities, the Laboratories raise the public's awareness of atmospheric science by presenting public lectures and demonstrations, by making scientific data available to wide audiences, by teaching, and by mentoring students and teachers. The Atmosphere Laboratories make substantial efforts to attract and recruit new scientists to the various areas of atmospheric research. We strongly encourage the establishment of partnerships with Federal and state agencies that have operational responsibilities to promote the societal application of our science products. This report describes our role in NASA's mission, provides highlights of our research scope and activities, and summarizes our scientists' major

  1. ESO PR Highlights in 2006

    Science.gov (United States)

    2007-01-01

    Last year proved to be another exceptional year for the European organisation for ground-based astronomy. ESO should begin the New Year with two new member states: Spain (PR 05/06) and the Czech Republic (PR 52/06). ESO PR Highlights 2006 2006 was a year of renovation and revolution in the world of planets. A new Earth-like exoplanet has been discovered (PR 03/06) using a network of telescopes from all over the world (including the Danish 1.54-m one at ESO La Silla). It is not the only child of this fruitful year: thanks to the combined use of ESO's Very Large Telescope (VLT) and La Silla instruments, a surprising system of twin giant exoplanets was found (PR 29/06), and a trio of Neptune-like planets hosted by a nearby star were identified (PR 18/06). These results open new perspectives on the search for habitable zones and on the understanding of the mechanism of planet formation. The VISIR instrument on the VLT has been providing unique information to answer this last question, by supplying a high resolution view of a planet-forming disc (PR 36/06). There are not only new members in the planets' register: during the General Assembly of the International Astronomical Union held in Prague (Czech Republic), it was decided that Pluto is not a planet anymore but a 'dwarf planet'. Whatever its status, Pluto still has a satellite, Charon, whose radius and density have been measured more accurately by observing a rare occultation from different sites, including Cerro Paranal (PR 02/06). The scientific community dedicated 2006 to the great physicist James Clerk Maxwell (it was the 175th anniversary of the birth): without his electromagnetic theory of light, none of the astonishing discoveries of modern physics could have been achieved. Nowadays we can look at distant galaxies in great detail: the GIRAFFE spectrograph on the VLT revealed that galaxies 6 billion years ago had the same amount of dark matter relative to stars than nowadays (PR 10/06), while SINFONI gave an

  2. Thin tube testing by eddy currents

    International Nuclear Information System (INIS)

    David, Bernard; Pigeon, Michel

    1981-01-01

    It is often necessary to define test conditions in eddy current testing, in consequence rules and laws allowing a rapid choice of these conditions are welcome. The similarity law, given by Forster, using the reduced frequency f/fg, allows extrapolation of results from an object to one another, if these two objects are similar (i.e. all their dimensions are proportional). In a particular case, often met, a law going further is given to describe, in a sole way, eddy current behaviour using the reduced frequency in all thin tubes (internal to external diameter ratio between 0.85 to 1). For instance working at f/fe=2 defines the same verification leading to identical results, whatever the nature, the diameter or the thickness may be, if the tubes are thin. A diagram is given and a slide-rule, based on this principle, has been realized [fr

  3. Computer modelling of eddy current probes

    International Nuclear Information System (INIS)

    Sullivan, S.P.

    1992-01-01

    Computer programs have been developed for modelling impedance and transmit-receive eddy current probes in two-dimensional axis-symmetric configurations. These programs, which are based on analytic equations, simulate bobbin probes in infinitely long tubes and surface probes on plates. They calculate probe signal due to uniform variations in conductor thickness, resistivity and permeability. These signals depend on probe design and frequency. A finite element numerical program has been procured to calculate magnetic permeability in non-linear ferromagnetic materials. Permeability values from these calculations can be incorporated into the above analytic programs to predict signals from eddy current probes with permanent magnets in ferromagnetic tubes. These programs were used to test various probe designs for new testing applications. Measurements of magnetic permeability in magnetically biased ferromagnetic materials have been performed by superimposing experimental signals, from special laboratory ET probes, on impedance plane diagrams calculated using these programs. (author). 3 refs., 2 figs

  4. Large Eddy Simulation for Compressible Flows

    CERN Document Server

    Garnier, E; Sagaut, P

    2009-01-01

    Large Eddy Simulation (LES) of compressible flows is still a widely unexplored area of research. The authors, whose books are considered the most relevant monographs in this field, provide the reader with a comprehensive state-of-the-art presentation of the available LES theory and application. This book is a sequel to "Large Eddy Simulation for Incompressible Flows", as most of the research on LES for compressible flows is based on variable density extensions of models, methods and paradigms that were developed within the incompressible flow framework. The book addresses both the fundamentals and the practical industrial applications of LES in order to point out gaps in the theoretical framework as well as to bridge the gap between LES research and the growing need to use it in engineering modeling. After introducing the fundamentals on compressible turbulence and the LES governing equations, the mathematical framework for the filtering paradigm of LES for compressible flow equations is established. Instead ...

  5. Pulsed eddy currents: principle and applications

    International Nuclear Information System (INIS)

    Bernard, A.; Coutanceau, N.

    1993-04-01

    Eddy currents are widely used as a non destructive testing technique specially for heat exchanger testing. The specificities of pulsed eddy current testing are analyzed in terms of probe design and signal processing. The specific applications are detailed. They are divided in two parts. First part, deals with the two main applications of the high peak energy supplied to the probe. One concerns the design of focused probes used for the detection of small defects in irradiated fuel rods. The other concerns the saturation of ferromagnetic materials in order to test the full thickness of the exchanger tubes. Second part, deals with applications of the wide and low frequency spectrum generated by the pulse source. It enables the testing of thick materials, and the detection of sub-surface defects. It has been tested on austenitic steel (nuclear pressure vessel nozzle), multilayered structures of aluminium alloys (aeronautics) and sleeved structures (nuclear pressure vessel head penetrations through thermal sleeves)

  6. Scalar Similarity for Relaxed Eddy Accumulation Methods

    Science.gov (United States)

    Ruppert, Johannes; Thomas, Christoph; Foken, Thomas

    2006-07-01

    The relaxed eddy accumulation (REA) method allows the measurement of trace gas fluxes when no fast sensors are available for eddy covariance measurements. The flux parameterisation used in REA is based on the assumption of scalar similarity, i.e., similarity of the turbulent exchange of two scalar quantities. In this study changes in scalar similarity between carbon dioxide, sonic temperature and water vapour were assessed using scalar correlation coefficients and spectral analysis. The influence on REA measurements was assessed by simulation. The evaluation is based on observations over grassland, irrigated cotton plantation and spruce forest. Scalar similarity between carbon dioxide, sonic temperature and water vapour showed a distinct diurnal pattern and change within the day. Poor scalar similarity was found to be linked to dissimilarities in the energy contained in the low frequency part of the turbulent spectra ( definition.

  7. Multi-frequency eddy current testing method

    International Nuclear Information System (INIS)

    Levy, R.; Gallet, G.

    1980-01-01

    Monitoring by multi-frequency eddy currents has been used since 1975 in French nuclear stations; this method applies perfectly to examinations in non-irradiated surroundings. The restrictions connected with operations in controlled zones (radioactivity) have led to the development of a delayed analysis device which in no way changes the principle of the method, but allows greater flexibility of use by reducing the volume of equipment needed and by limiting the intervention of personnel to a strict minimum [fr

  8. Parameterized and resolved Southern Ocean eddy compensation

    Science.gov (United States)

    Poulsen, Mads B.; Jochum, Markus; Nuterman, Roman

    2018-04-01

    The ability to parameterize Southern Ocean eddy effects in a forced coarse resolution ocean general circulation model is assessed. The transient model response to a suite of different Southern Ocean wind stress forcing perturbations is presented and compared to identical experiments performed with the same model in 0.1° eddy-resolving resolution. With forcing of present-day wind stress magnitude and a thickness diffusivity formulated in terms of the local stratification, it is shown that the Southern Ocean residual meridional overturning circulation in the two models is different in structure and magnitude. It is found that the difference in the upper overturning cell is primarily explained by an overly strong subsurface flow in the parameterized eddy-induced circulation while the difference in the lower cell is mainly ascribed to the mean-flow overturning. With a zonally constant decrease of the zonal wind stress by 50% we show that the absolute decrease in the overturning circulation is insensitive to model resolution, and that the meridional isopycnal slope is relaxed in both models. The agreement between the models is not reproduced by a 50% wind stress increase, where the high resolution overturning decreases by 20%, but increases by 100% in the coarse resolution model. It is demonstrated that this difference is explained by changes in surface buoyancy forcing due to a reduced Antarctic sea ice cover, which strongly modulate the overturning response and ocean stratification. We conclude that the parameterized eddies are able to mimic the transient response to altered wind stress in the high resolution model, but partly misrepresent the unperturbed Southern Ocean meridional overturning circulation and associated heat transports.

  9. Cyclonic entrainment of preconditioned shelf waters into a frontal eddy

    Science.gov (United States)

    Everett, J. D.; Macdonald, H.; Baird, M. E.; Humphries, J.; Roughan, M.; Suthers, I. M.

    2015-02-01

    The volume transport of nutrient-rich continental shelf water into a cyclonic frontal eddy (entrainment) was examined from satellite observations, a Slocum glider and numerical simulation outputs. Within the frontal eddy, parcels of water with temperature/salinity signatures of the continental shelf (18-19°C and >35.5, respectively) were recorded. The distribution of patches of shelf water observed within the eddy was consistent with the spiral pattern shown within the numerical simulations. A numerical dye tracer experiment showed that the surface waters (≤50 m depth) of the frontal eddy are almost entirely (≥95%) shelf waters. Particle tracking experiments showed that water was drawn into the eddy from over 4° of latitude (30-34.5°S). Consistent with the glider observations, the modeled particles entrained into the eddy sunk relative to their initial position. Particles released south of 33°S, where the waters are cooler and denser, sunk 34 m deeper than their release position. Distance to the shelf was a critical factor in determining the volume of shelf water entrained into the eddy. Entrainment reduced to 0.23 Sv when the eddy was furthest from the shelf, compared to 0.61 Sv when the eddy was within 10 km of the shelf. From a biological perspective, quantifying the entrainment of shelf water into frontal eddies is important, as it is thought to play a significant role in providing an offshore nursery habitat for coastally spawned larval fish.

  10. Eddy current inspection of stationary blade rings

    International Nuclear Information System (INIS)

    Krzywosz, K.J.; Hastings, S.N.

    1994-01-01

    Stationary turbine blade rings in a US power plant have experienced chloride-induced cracking. Failure analysis determined two types of cracking mechanisms: corrosion fatigue cracking confined to the leading edge of the outer shroud; and stress corrosion cracking present all over the blade surface. Fluorescent dye penetrant is typically used to detect and size cracks. However, it requires cleaning the blade rings by sandblasting to obtain reliable inspection results. Sand blasting in turn requires sealing the lower half of the turbine housing to prevent sand from contaminating the rest of the power plant components. Furthermore, both the penetrant examination and the removal of the sand are time consuming and costly. An alternative NDE technique is desirable which requires no pre-cleaning of the blade and a quick go/no-go inspection with the capability of estimating the crack length. This paper presents an innovative eddy current technique which meets the desired objectives by incorporating the use of specially designed contoured scanners equipped with an array of pancake coils. A set of eddy current pancake coils housed in three different scanners is used to manually scan and inspect the convex side of the stationary blade rings. The pancake coils are operated in a transmit/receive mode using two separate eddy current instruments. This paper presents the inspection concept, including scanner and probe designs, and test results from the various stages of multiple blade rings

  11. Large eddy simulation of bundle turbulent flows

    International Nuclear Information System (INIS)

    Hassan, Y.A.; Barsamian, H.R.

    1995-01-01

    Large eddy simulation may be defined as simulation of a turbulent flow in which the large scale motions are explicitly resolved while the small scale motions are modeled. This results into a system of equations that require closure models. The closure models relate the effects of the small scale motions onto the large scale motions. There have been several models developed, the most popular is the Smagorinsky eddy viscosity model. A new model has recently been introduced by Lee that modified the Smagorinsky model. Using both of the above mentioned closure models, two different geometric arrangements were used in the simulation of turbulent cross flow within rigid tube bundles. An inlined array simulations was performed for a deep bundle (10,816 nodes) as well as an inlet/outlet simulation (57,600 nodes). Comparisons were made to available experimental data. Flow visualization enabled the distinction of different characteristics within the flow such as jet switching effects in the wake of the bundle flow for the inlet/outlet simulation case, as well as within tube bundles. The results indicate that the large eddy simulation technique is capable of turbulence prediction and may be used as a viable engineering tool with the careful consideration of the subgrid scale model. (author)

  12. Eddy current testing using digital technology

    International Nuclear Information System (INIS)

    Houseman, H.E.; Lamb, L.T.; Kitson, B.

    1985-01-01

    Eddy current inspection techniques have been used extensively in industry as an accepted method of non-destructive testing. The application of this technology has proven invaluable for both the control of product quality during the manufacturing process as well as the verification of material integrity throughout the life of a given component. One of the major areas in the power industry where eddy current techniques have been used is for the inspection of installed tubing in various heat exchangers including the steam generators of pressurized water reactor (PWR) nuclear steam supply systems. As increased emphasis is placed upon the operability and safety of these components, test instrumentation has been advanced to improve the efficiency and reliability of inservice inspections. At the same time, plant owners along with manufacturers and inspection service vendors are developing analytical tools for assessing the inspection results. One of the techniques that offers significant potential has been made possible by recent advances in digital technology. The application of digital techniques to the eddy current method offers not only a means to improve the test instrumentation but also an environment whereby other facets of the inservice inspection effort can be enchanced

  13. Three-dimensional Improved Delayed Detached Eddy Simulation of a two-bladed vertical axis wind turbine

    International Nuclear Information System (INIS)

    Lei, Hang; Zhou, Dai; Bao, Yan; Li, Ye; Han, Zhaolong

    2017-01-01

    Highlights: • The Improved Delayed Detached Eddy Simulation and polyhedral mesh are utilized. • Power coefficient and wake velocity are compared between experiments and simulations. • Improved Delayed Detached Eddy Simulation shows more vortices under dynamic stall. • Different scales of flow separations are distinguished by these two models. - Abstract: The aerodynamic performance of a two-bladed vertical axis wind turbine is investigated using the turbulence model of the Improved Delayed Detached Eddy Simulation and the polyhedral mesh. The sliding mesh technique is used to simulate the rotation of the rotor. Meanwhile, the results obtained by the shear stress transport k-ω model are presented as contrast. Then, the simulated power coefficients at different tip speed ratios and the wake velocity are validated by comparison with the experimental data from available literature. It is shown that the power coefficients and wake velocity predicted by the Improved Delayed Detached Eddy Simulation are closer to the experimental data than those by the shear stress transport k-ω model. The pressure distributions predicted by the two turbulence models show different degrees of discrepancies in different scales of flow separation. By comparing the vorticity magnitude graphs, the Improved Delayed Detached Eddy Simulation is found to be able to capture more exquisite vortices after the flow separations. Limited by its inherent ability, the shear stress transport k-ω model predicts vortices that are less realistic than those of Improved Delayed Detached Eddy Simulation. Hence, it may cause some errors in predicting the pressure distributions, especially when the blades suffer dynamic stall. It is demonstrated that the Improved Delayed Detached Eddy Simulation is regarded as a reliable model to analyze the aerodynamic performance of vertical axis wine turbines.

  14. Eddy damping effect of additional conductors in superconducting levitation systems

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Zhao-Fei; Gou, Xiao-Fan, E-mail: xfgou@hhu.edu.cn

    2015-12-15

    Highlights: • In this article, for the eddy current damper attached to the HTSC, we • quantitatively investigated the damping coefficient c, damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. • presented four different arrangements of the copper damper, and comparatively studied their damping effects and Joule heating, and finally proposed the most advisable arrangement. - Abstract: Passive superconducting levitation systems consisting of a high temperature superconductor (HTSC) and a permanent magnet (PM) have demonstrated several fascinating applications such as the maglev system, flywheel energy storage. Generally, for the HTSC–PM levitation system, the HTSC with higher critical current density J{sub c} can obtain larger magnetic force to make the PM levitate over the HTSC (or suspended below the HTSC), however, the process of the vibration of the levitated PM, provides very limited inherent damping (essentially hysteresis). To improve the dynamic stability of the levitated PM, eddy damping of additional conductors can be considered as the most simple and effective approach. In this article, for the HTSC–PM levitation system with an additional copper damper attached to the HTSC, we numerically and comprehensively investigated the damping coefficient c, damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. Furthermore, we comparatively studied four different arrangements of the copper damper, on the comprehensive analyzed the damping effect, efficiency (defined by c/V{sub Cu}, in which V{sub Cu} is the volume of the damper) and Joule heating, and finally presented the most advisable arrangement.

  15. Large Eddy Simulation for an inherent boron dilution transient

    International Nuclear Information System (INIS)

    Jayaraju, S.T.; Sathiah, P.; Komen, E.M.J.; Baglietto, E.

    2013-01-01

    Highlights: • Large Eddy Simulation is performed for a transient boron dilution scenario in the scaled experimental facility of ROCOM. • Fully conformal polyhedral grid of 14 million is created to capture all details of the domain. • Systematic multi-step validation methodology is followed to assess the accuracy of LES model. • For the presently simulated BDT scenario, the LES results lend support to its reliability in consistently predicting the slug transport in the RPV. -- Abstract: The present paper focuses on the validation and applicability of large eddy simulation (LES) to analyze the transport and mixing in the reactor pressure vessel (RPV) during an inherent boron dilution transient (BDT) scenario. Extensive validation data comes from relevant integral tests performed in the scaled ROCOM experimental facility. The modeling of sub-grid-scales is based on the WALE model. A fully conformal polyhedral grid of about 15 million cells is constructed to capture all details in the domain, including the complex structures of the lower-plenum. Detailed qualitative and quantitative validations are performed by following a systematic multi-step validation methodology. Qualitative comparisons to the experimental data in the cold legs, downcomer and the core inlet showed good predictions by the LES model. Minor deviations seen in the quantitative comparisons are rigorously quantified. A key parameter which is affecting the core neutron kinetics response is the value of highest deborated slug concentration that occurs at the core inlet during the transient. Detailed analyses are made at the core inlet to evaluate not only the value of the maximum slug concentration, but also the location and the time at which it occurs during the transient. The relative differences between the ensemble averaged experimental data and CFD predictions were within the range of relative differences seen within 10 different experimental realizations. For the studied scenario, the

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

    Science.gov (United States)

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

    2018-04-01

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

  17. Large eddy simulation of n-heptane spray combustion in partially premixed combustion regime with linear eddy model

    International Nuclear Information System (INIS)

    Xiao, Gang; Jia, Ming; Wang, Tianyou

    2016-01-01

    Spray combustion of n-heptane in a constant-volume vessel under engine-relevant conditions was investigated using linear eddy model in the framework of large eddy simulation. In this numerical approach, turbulent mixing was traced by an innovative stochastic approach instead of the conventional gradient diffusion model. Chemical reaction rates were calculated with the consideration of the sub-grid scale spatial fluctuations of reactive scalars. Turbulence-chemistry interactions were represented by the separated treatments of the underlying processes including turbulent stirring, chemical reaction, and molecular diffusion. The model was validated against the experimental data of ignition delay times, chemiluminescence images, and soot images from Sandia National Laboratories. Numerical results showed that the ignition process changed from the temperature-controlled regime to the mixing-controlled regime as the initial ambient temperature increased from 800 K to 1000 K. The premixed flame and the diffusion flame coexisted, while the gross heat release rate was found to be dominated by the premixed flame. The temperature fluctuation was mainly observed around the spray jet due to the cooling effect of the fuel vaporization. The fluctuations were more significantly smoothed out by the high-temperature flame than the low-temperature flame. The mean temperature would be overpredicted if the sub-grid temperature fluctuation was neglected. - Highlights: • Turbulent mixing is traced by stochastic method instead of gradient diffusion model. • Sub-grid scale fluctuations of reactive scalars are captured. • Ignition process varies from temperature-controlled to mixing-controlled regime. • Temperature fluctuation can be smoothed out by high-temperature flame. • The heat release rate is dominated by the premixed flame.

  18. Eddy current detection of corrosion damage in heat exchanger tubes

    International Nuclear Information System (INIS)

    Van Drunen, G.; Cecco, V.S.; Carter, J.R.

    1980-05-01

    Eddy current is often the most effective nondestructive test method available for in-service inspection of small bore tubing in heat exchangers. The basic principles, advantages and shortcomings of the technique are outlined. Typical eddy current indications from corrosion-related defects such as stress corrosion cracks, pitting and tube denting under support plates are presented. Eddy current signals from features such as magnetite deposits and ferromagnetic inclusions which might be mistaken for defects are also discussed. (auth)

  19. Observations of near-inertial kinetic energy inside mesoscale eddies.

    Science.gov (United States)

    Garcia Gomez, B. I.; Pallas Sanz, E.; Candela, J.

    2016-02-01

    The near-nertial oscillations (NIOs), generated by the wind stress on the surface mixed layer, are the inertia gravity waves with the lowest frequency and the highest kinetic energy. NIOs are important because they drive vertical mixing in the interior ocean during wave breaking events. Although the interaction between NIOs and mesoescale eddies has been reported by several authors, these studies are mostly analytical and numerical, and only few observational studies have attempted to show the differences in near-inertial kinetic energy (KEi) between anticyclonic and cyclonic eddies. In this work the spatial structure of the KEi inside the mesoscale eddies is computed using daily satellite altimetry and observations of horizontal velocity from 30 moorings equipped with acoustic Doppler current profilers in the western Gulf of Mexico. Consistent to theory, the obtained four-year KEi-composites show two times more KEi inside the anticyclonic eddies than inside the cyclonic ones. The vertical cross-sections of the KEi-composites show that the KEi is mainly located near the surface and at the edge of the cyclonic eddies (positive vorticity), whereas the KEi in anticyclonic eddies (negative vorticity) is maximum in the eddy's center and near to the base of the eddy where the NIOs become more inertial, are trapped, and amplified. A relative maximum in the upper anticyclonic eddy is also observed. The cyclonic eddies present a maximum of KEi near to the surface at 70 m, while the maximum of KEi in the anticyclonic eddies occurs between 800 and 1000 m. It is also shown the dependence between the distribution and magnitude of the KEi and the eddy's characteristics such as radius, vorticity, and amplitude.

  20. Eddy current seminar, 24-26 Mar 1986

    International Nuclear Information System (INIS)

    Emson, C.R.I.

    1986-06-01

    The paper concerns the Eddy Current Seminars, held at the Rutherford Appleton Laboratory, United Kingdom, March 1986. Twenty two papers were presented on eddy current phenomena, and two of the papers are indexed separately. The first deals with a finite difference scheme for time dependent eddy currents in Tokamaks, the second is an analysis of the FELIX experiments with cantilevered beams and hollow cylinders. (UK)

  1. Dispersion of tracers by the oceanic eddy field modelling programme

    International Nuclear Information System (INIS)

    Richards, K.J.

    1986-01-01

    A numerical model has been developed to study the dispersion of tracers by the oceanic eddy field. The study is designed to investigate the horizontal and vertical structure of the eddies and how this structure is influenced by the bottom topography. It is found that hills and valleys have a strong effect on the eddies above them. The flow close to the bottom has a tendency to be steered by the height contours. The surface and bottom flows become decorrelated and the vertical variation of the kinetic energy of the eddies is increased with higher topographic features. (author)

  2. Eddy Current Assessment of Engineered Components Containing Nanofibers

    Science.gov (United States)

    Ko, Ray T.; Hoppe, Wally; Pierce, Jenny

    2009-03-01

    The eddy current approach has been used to assess engineered components containing nanofibers. Five specimens with different programmed defects were fabricated. A 4-point collinear probe was used to verify the electrical resistivity of each specimen. The liftoff component of the eddy current signal was used to test two extreme cases with different nano contents. Additional eddy current measurements were also used in detecting a missing nano layer simulating a manufacturing process error. The results of this assessment suggest that eddy current liftoff measurement can be a useful tool in evaluating the electrical properties of materials containing nanofibers.

  3. Eddy Covariance Method for CO2 Emission Measurements: CCS Applications, Principles, Instrumentation and Software

    Science.gov (United States)

    Burba, George; Madsen, Rod; Feese, Kristin

    2013-04-01

    and technical papers. A free open-source software package with a user-friendly interface was developed accordingly for computing final fully corrected CO2 emission numbers [10]. The presentation covers highlights of the eddy covariance method, its application to geological carbon sequestration, key requirements, instrumentation and software, and reviews educational resources particularly useful for carbon sequestration research. References: [1] Aubinet, M., T. Vesala, and D. Papale (Eds.), 2012. Eddy Covariance: A Practical Guide to Measurement and Data Analysis. Springer-Verlag, 442 pp. [2] Foken T., 2008. Micrometeorology. Springer-Verlag, 308 pp. [4] Finley, R., 2009. An Assessment of Geological Carbon Sequestration in the Illinois Basin Overview of the Decatur-Illinois Basin Site. MGSC, http://www.istc.illinois.edu/info/govs_awards_docs/2009-GSA-1100-Finley.pdf [5] Liu, G. (Ed.), 2012. Greenhouse Gases: Capturing, Utilization and Reduction. Intech, 338 pp. [6] LI-COR Biosciences, 2011. Surface Monitoring for Geologic Carbon Sequestration Monitoring: Methods, Instrumentation, and Case Studies. LI-COR Biosciences, Pub. 980-11916, 15 pp. [7] Benson, S., 2006. Monitoring carbon dioxide sequestration in deep geological formations for inventory verification and carbon credits, SPE-102833, Presentation [8] Lewicki, J., G. Hilley, M. Fischer, L. Pan, C. Olden-burg, C. Dobeck, and L. Spangler, 2009.Eddy covariance observations of leakage during shallow subsurface CO2 releases. Journal of Geophys Res, 114: D12302 [9] Burba, G., 2013. Eddy Covariance Method for Scientific, Industrial, Agricultural and Regulatory Applications. LI-COR Biosciences, 328 pp. [10] LI-COR Biosciences, 2012. EddyPro 4.0: Help and User's Guide. Lincoln, NE, 208 pp.

  4. Controls on the global distribution of contourite drifts: Insights from an eddy-resolving ocean model

    Science.gov (United States)

    Thran, Amanda C.; Dutkiewicz, Adriana; Spence, Paul; Müller, R. Dietmar

    2018-05-01

    Contourite drifts are anomalously high sediment accumulations that form due to reworking by bottom currents. Due to the lack of a comprehensive contourite database, the link between vigorous bottom water activity and drift occurrence has yet to be demonstrated on a global scale. Using an eddy-resolving ocean model and a new georeferenced database of 267 contourites, we show that the global distribution of modern contourite drifts strongly depends on the configuration of the world's most powerful bottom currents, many of which are associated with global meridional overturning circulation. Bathymetric obstacles frequently modify flow direction and intensity, imposing additional finer-scale control on drift occurrence. Mean bottom current speed over contourite-covered areas is only slightly higher (2.2 cm/s) than the rest of the global ocean (1.1 cm/s), falling below proposed thresholds deemed necessary to re-suspend and redistribute sediments (10-15 cm/s). However, currents fluctuate more frequently and intensely over areas with drifts, highlighting the role of intermittent, high-energy bottom current events in sediment erosion, transport, and subsequent drift accumulation. We identify eddies as a major driver of these bottom current fluctuations, and we find that simulated bottom eddy kinetic energy is over three times higher in contourite-covered areas in comparison to the rest of the ocean. Our work supports previous hypotheses which suggest that contourite deposition predominantly occurs due to repeated acute events as opposed to continuous reworking under average-intensity background flow conditions. This suggests that the contourite record should be interpreted in terms of a bottom current's susceptibility to experiencing periodic, high-speed current events. Our results also highlight the potential role of upper ocean dynamics in contourite sedimentation through its direct influence on deep eddy circulation.

  5. Essential parameters in eddy current inspection

    International Nuclear Information System (INIS)

    Stepinski, T.

    2000-05-01

    Our aim was to qualitatively analyze a number of variables that may affect the result of eddy current (EC) inspection but because of various reasons are not considered as essential in common practice. In the report we concentrate on such variables that can vary during or between inspections but their influence is not determined during routine calibrations. We present a qualitative analysis of the influence of the above-mentioned variables on the ability to detect and size flaws using mechanized eddy current testing (ET). ET employs some type of coil or probe, sensing magnetic flux generated by eddy currents induced in the tested specimen. An amplitude-phase modulated signal (with test frequency f0 ) from the probe is sensed by the EC instrument. The amplitude-phase modulated signal is amplified and demodulated in phase-sensitive detectors removing carrier frequency f0 from the signal. The detectors produce an in-phase and a quadrature component of the signal defining it as a point in the impedance plane. Modern instruments are provided with a screen presenting the demodulated and filtered signal in complex plane. We focus on such issues, related to the EC equipment as, probe matching, distortion introduced by phase discriminators and signal filters, and the influence of probe resolution and lift-off on sizing. The influence of different variables is investigated by means of physical reasoning employing theoretical models and demonstrated using simulated and real EC signals. In conclusion, we discuss the way in which the investigated variables may affect the result of ET. We also present a number of practical recommendations for the users of ET and indicate the areas that are to be further analyzed

  6. EddyOne automated analysis of PWR/WWER steam generator tubes eddy current data

    International Nuclear Information System (INIS)

    Nadinic, B.; Vanjak, Z.

    2004-01-01

    INETEC Institute for Nuclear Technology developed software package called Eddy One which has option of automated analysis of bobbin coil eddy current data. During its development and on site use, many valuable lessons were learned which are described in this article. In accordance with previous, the following topics are covered: General requirements for automated analysis of bobbin coil eddy current data; Main approaches to automated analysis; Multi rule algorithms for data screening; Landmark detection algorithms as prerequisite for automated analysis (threshold algorithms and algorithms based on neural network principles); Field experience with Eddy One software; Development directions (use of artificial intelligence with self learning abilities for indication detection and sizing); Automated analysis software qualification; Conclusions. Special emphasis is given on results obtained on different types of steam generators, condensers and heat exchangers. Such results are then compared with results obtained by other automated software vendors giving clear advantage to INETEC approach. It has to be pointed out that INETEC field experience was collected also on WWER steam generators what is for now unique experience.(author)

  7. Magnetic Field of Conductive Objects as Superposition of Elementary Eddy Currents and Eddy Current Tomography

    Science.gov (United States)

    Sukhanov, D. Ya.; Zav'yalova, K. V.

    2018-03-01

    The paper represents induced currents in an electrically conductive object as a totality of elementary eddy currents. The proposed scanning method includes measurements of only one component of the secondary magnetic field. Reconstruction of the current distribution is performed by deconvolution with regularization. Numerical modeling supported by the field experiments show that this approach is of direct practical relevance.

  8. Inverse source problems for eddy current equations

    International Nuclear Information System (INIS)

    Rodríguez, Ana Alonso; Valli, Alberto; Camaño, Jessika

    2012-01-01

    We study the inverse source problem for the eddy current approximation of Maxwell equations. As for the full system of Maxwell equations, we show that a volume current source cannot be uniquely identified by knowledge of the tangential components of the electromagnetic fields on the boundary, and we characterize the space of non-radiating sources. On the other hand, we prove that the inverse source problem has a unique solution if the source is supported on the boundary of a subdomain or if it is the sum of a finite number of dipoles. We address the applicability of this result for the localization of brain activity from electroencephalography and magnetoencephalography measurements. (paper)

  9. Recent Ship, Satellite and Autonomous Observations of Southern Ocean Eddies

    Science.gov (United States)

    Strutton, P. G.; Moreau, S.; Llort, J.; Phillips, H. E.; Patel, R.; Della Penna, A.; Langlais, C.; Lenton, A.; Matear, R.; Dawson, H.; Boyd, P. W.

    2016-12-01

    The Southern Ocean is the area of greatest uncertainty regarding the exchange of CO2 between the ocean and atmosphere. It is also a region of abundant energetic eddies that significantly impact circulation and biogeochemistry. In the Indian sector of the Southern Ocean, cyclonic eddies are unusual in that they are upwelling favorable, as for cyclonic eddies elsewhere, but during summer they are low in silicate and phytoplankton biomass. The reverse is true for anticyclonic eddies in that they have counter-intuitive positive chlorophyll anomalies in summer. Similar but less obvious patterns occur in the Pacific and Atlantic sectors. Using ship, satellite and autonomous observations in the region south of Australia, the physical and biogeochemical signatures of both types of eddies were documented in 2016. A cyclonic eddy that lived for seven weeks exhibited doming isopycnals indicative of upwelling. However, low surface silicate and chlorophyll concentrations appeared to be characteristic of surface waters to the south where the eddy formed. Higher chlorophyll was confined to filaments at the eddy edge. Surface nitrate and phosphate concentrations were more than sufficient for a bloom of non-siliceous phytoplankton to occur. Acoustic observations from a high resolution TRIAXUS transect through the eddy documented high zooplankton biomass in the upper 150m. It is hypothesized that a non-diatom bloom was prevented by grazing pressure, but light may have also been an important limiting resource in late summer (April). Two SOCCOM floats that were deployed in the eddy field continued to monitor the physics, nitrate and bio-optics through the transition to winter. These observations across complementary platforms have identified and then explained the reason for these unexpected biological anomalies in an energetic and globally important region of the global ocean. Understanding the role of eddies in this region will be critical to the representation of mesoscale

  10. Turbulent eddy diffusion models in exposure assessment - Determination of the eddy diffusion coefficient.

    Science.gov (United States)

    Shao, Yuan; Ramachandran, Sandhya; Arnold, Susan; Ramachandran, Gurumurthy

    2017-03-01

    The use of the turbulent eddy diffusion model and its variants in exposure assessment is limited due to the lack of knowledge regarding the isotropic eddy diffusion coefficient, D T . But some studies have suggested a possible relationship between D T and the air changes per hour (ACH) through a room. The main goal of this study was to accurately estimate D T for a range of ACH values by minimizing the difference between the concentrations measured and predicted by eddy diffusion model. We constructed an experimental chamber with a spatial concentration gradient away from the contaminant source, and conducted 27 3-hr long experiments using toluene and acetone under different air flow conditions (0.43-2.89 ACHs). An eddy diffusion model accounting for chamber boundary, general ventilation, and advection was developed. A mathematical expression for the slope based on the geometrical parameters of the ventilation system was also derived. There is a strong linear relationship between D T and ACH, providing a surrogate parameter for estimating D T in real-life settings. For the first time, a mathematical expression for the relationship between D T and ACH has been derived that also corrects for non-ideal conditions, and the calculated value of the slope between these two parameters is very close to the experimentally determined value. The values of D T obtained from the experiments are generally consistent with values reported in the literature. They are also independent of averaging time of measurements, allowing for comparison of values obtained from different measurement settings. These findings make the use of turbulent eddy diffusion models for exposure assessment in workplace/indoor environments more practical.

  11. Eddy current testing of composite pressure vessels

    Science.gov (United States)

    Casperson, R.; Pohl, R.; Munzke, D.; Becker, B.; Pelkner, M.

    2018-04-01

    The use of composite pressure vessels instead of conventional vessels made of steel or aluminum grew strongly over the last decade. The reason for this trend is the tremendous weight saving in the case of composite vessels. However, the long-time behavior is not fully understood for filling and discharging cycles and creep strength and their influence on the CFRP coating (carbon fiber reinforced plastics) and the internal liner (steel, aluminum, or plastics). The CFRP ensures the pressure resistance while the inner liner is used as a container for liquid or gas. To overcome the missing knowledge of aging, BAM started an internal project to investigate degradation of these material systems. Therefore, applicable testing methods like eddy current testing are needed. Normally, high-frequency eddy current testing (HF-ET, f > 10 MHz) is deployed for CFRP due to its low conductivity of the fiber, which is in the order of 0.01 MS/s, and the capacitive coupling between the fibers. Nevertheless, in some cases conventional ET can be applied. We show a concise summary of studies on the application of conventional ET of composite pressure vessels.

  12. Large-Eddy Simulation of Subsonic Jets

    International Nuclear Information System (INIS)

    Vuorinen, Ville; Wehrfritz, Armin; Yu Jingzhou; Kaario, Ossi; Larmi, Martti; Boersma, Bendiks Jan

    2011-01-01

    The present study deals with development and validation of a fully explicit, compressible Runge-Kutta-4 (RK4) Navier-Stokes solver in the opensource CFD programming environment OpenFOAM. The background motivation is to shift towards explicit density based solution strategy and thereby avoid using the pressure based algorithms which are currently proposed in the standard OpenFOAM release for Large-Eddy Simulation (LES). This shift is considered necessary in strongly compressible flows when Ma > 0.5. Our application of interest is related to the pre-mixing stage in direct injection gas engines where high injection pressures are typically utilized. First, the developed flow solver is discussed and validated. Then, the implementation of subsonic inflow conditions using a forcing region in combination with a simplified nozzle geometry is discussed and validated. After this, LES of mixing in compressible, round jets at Ma = 0.3, 0.5 and 0.65 are carried out. Respectively, the Reynolds numbers of the jets correspond to Re = 6000, 10000 and 13000. Results for two meshes are presented. The results imply that the present solver produces turbulent structures, resolves a range of turbulent eddy frequencies and gives also mesh independent results within satisfactory limits for mean flow and turbulence statistics.

  13. Mesoscale eddies are oases for higher trophic marine life

    KAUST Repository

    Godø , Olav R.; Samuelsen, Annette; Macaulay, Gavin J.; Patel, Ruben; Hjø llo, Solfrid Sæ tre; Horne, John; Kaartvedt, Stein; Johannessen, Johnny A.

    2012-01-01

    Mesoscale eddies stimulate biological production in the ocean, but knowledge of energy transfers to higher trophic levels within eddies remains fragmented and not quantified. Increasing the knowledge base is constrained by the inability of traditional sampling methods to adequately sample biological processes at the spatio-temporal scales at which they occur. By combining satellite and acoustic observations over spatial scales of 10 s of km horizontally and 100 s of m vertically, supported by hydrographical and biological sampling we show that anticyclonic eddies shape distribution and density of marine life from the surface to bathyal depths. Fish feed along density structures of eddies, demonstrating that eddies catalyze energy transfer across trophic levels. Eddies create attractive pelagic habitats, analogous to oases in the desert, for higher trophic level aquatic organisms through enhanced 3-D motion that accumulates and redistributes biomass, contributing to overall bioproduction in the ocean. Integrating multidisciplinary observation methodologies promoted a new understanding of biophysical interaction in mesoscale eddies. Our findings emphasize the impact of eddies on the patchiness of biomass in the sea and demonstrate that they provide rich feeding habitat for higher trophic marine life. 2012 God et al.

  14. Automatic analysis of signals during Eddy currents controls

    International Nuclear Information System (INIS)

    Chiron, D.

    1983-06-01

    A method and the corresponding instrument have been developed for automatic analysis of Eddy currents testing signals. This apparatus enables at the same time the analysis, every 2 milliseconds, of two signals at two different frequencies. It can be used either on line with an Eddy Current testing instrument or with a magnetic tape recorder [fr

  15. Mesoscale eddies are oases for higher trophic marine life.

    Directory of Open Access Journals (Sweden)

    Olav R Godø

    Full Text Available Mesoscale eddies stimulate biological production in the ocean, but knowledge of energy transfers to higher trophic levels within eddies remains fragmented and not quantified. Increasing the knowledge base is constrained by the inability of traditional sampling methods to adequately sample biological processes at the spatio-temporal scales at which they occur. By combining satellite and acoustic observations over spatial scales of 10 s of km horizontally and 100 s of m vertically, supported by hydrographical and biological sampling we show that anticyclonic eddies shape distribution and density of marine life from the surface to bathyal depths. Fish feed along density structures of eddies, demonstrating that eddies catalyze energy transfer across trophic levels. Eddies create attractive pelagic habitats, analogous to oases in the desert, for higher trophic level aquatic organisms through enhanced 3-D motion that accumulates and redistributes biomass, contributing to overall bioproduction in the ocean. Integrating multidisciplinary observation methodologies promoted a new understanding of biophysical interaction in mesoscale eddies. Our findings emphasize the impact of eddies on the patchiness of biomass in the sea and demonstrate that they provide rich feeding habitat for higher trophic marine life.

  16. Mesoscale eddies are oases for higher trophic marine life

    KAUST Repository

    Godø, Olav R.

    2012-01-17

    Mesoscale eddies stimulate biological production in the ocean, but knowledge of energy transfers to higher trophic levels within eddies remains fragmented and not quantified. Increasing the knowledge base is constrained by the inability of traditional sampling methods to adequately sample biological processes at the spatio-temporal scales at which they occur. By combining satellite and acoustic observations over spatial scales of 10 s of km horizontally and 100 s of m vertically, supported by hydrographical and biological sampling we show that anticyclonic eddies shape distribution and density of marine life from the surface to bathyal depths. Fish feed along density structures of eddies, demonstrating that eddies catalyze energy transfer across trophic levels. Eddies create attractive pelagic habitats, analogous to oases in the desert, for higher trophic level aquatic organisms through enhanced 3-D motion that accumulates and redistributes biomass, contributing to overall bioproduction in the ocean. Integrating multidisciplinary observation methodologies promoted a new understanding of biophysical interaction in mesoscale eddies. Our findings emphasize the impact of eddies on the patchiness of biomass in the sea and demonstrate that they provide rich feeding habitat for higher trophic marine life. 2012 God et al.

  17. Nonlinear Eddy Viscosity Models applied to Wind Turbine Wakes

    DEFF Research Database (Denmark)

    Laan, van der, Paul Maarten; Sørensen, Niels N.; Réthoré, Pierre-Elouan

    2013-01-01

    The linear k−ε eddy viscosity model and modified versions of two existing nonlinear eddy viscosity models are applied to single wind turbine wake simulations using a Reynolds Averaged Navier-Stokes code. Results are compared with field wake measurements. The nonlinear models give better results...

  18. Signal processing of eddy current three-dimensional maps

    International Nuclear Information System (INIS)

    Birac, C.; David, D.; Lamant, D.

    1987-01-01

    Digital processing of eddy current three-dimensional maps improves accuracy of detection: flattening, filtering, computing deconvolution, mapping new variables,.., give new possibilities for difficult test problems. With simulation of defects, probes, probe travels, it is now possible to compute new eddy current processes, without machining defects or building probes

  19. Eddy energy sources and flux in the Red Sea

    KAUST Repository

    Zhan, Peng; Subramanian, Aneesh C.; Kartadikaria, Aditya R.; Hoteit, Ibrahim

    2015-01-01

    the basin and by pumping the nutrient-enriched subsurface water to sustain the primary production. Previous observations and modeling work suggest that the Red Sea is rich of eddy activities. In this study, the eddy energy sources and sinks have been studied

  20. Properties, Mechanisms and Predictability of Eddies in the Red Sea

    KAUST Repository

    Zhan, Peng

    2018-04-01

    Eddies are one of the key features of the Red Sea circulation. They are not only crucial for energy conversion among dynamics at different scales, but also for materials transport across the basin. This thesis focuses on studying the characteristics of Red Sea eddies, including their temporal and spatial properties, their energy budget, the mechanisms of their evolution, and their predictability. Remote sensing data, in-situ observations, the oceanic general circulation model, and data assimilation techniques were employed in this thesis. The eddies in the Red Sea were first identified using altimeter data by applying an improved winding-angle method, based on which the statistical properties of those eddies were derived. The results suggested that eddies occur more frequently in the central basin of the Red Sea and exhibit a significant seasonal variation. The mechanisms of the eddies’ evolution, particularly the eddy kinetic energy budget, were then investigated based on the outputs of a long-term eddy resolving numerical model configured for the Red Sea with realistic forcing. Examination of the energy budget revealed that the eddies acquire the vast majority of kinetic energy through conversion of eddy available potential energy via baroclinic instability, which is intensified during winter. The possible factors modulating the behavior of the several observed eddies in the Red Sea were then revealed by conducting a sensitivity analysis using the adjoint model. These eddies were found to exhibit different sensitivities to external forcings, suggesting different mechanisms for their evolution. This is the first known adjoint sensitivity study on specific eddy events in the Red Sea and was hitherto not previously appreciated. The last chapter examines the predictability of Red Sea eddies using an ensemble-based forecasting and assimilation system. The forecast sea surface height was used to evaluate the overall performance of the short-term eddy

  1. A dynamic global-coefficient mixed subgrid-scale model for large-eddy simulation of turbulent flows

    International Nuclear Information System (INIS)

    Singh, Satbir; You, Donghyun

    2013-01-01

    Highlights: ► A new SGS model is developed for LES of turbulent flows in complex geometries. ► A dynamic global-coefficient SGS model is coupled with a scale-similarity model. ► Overcome some of difficulties associated with eddy-viscosity closures. ► Does not require averaging or clipping of the model coefficient for stabilization. ► The predictive capability is demonstrated in a number of turbulent flow simulations. -- Abstract: A dynamic global-coefficient mixed subgrid-scale eddy-viscosity model for large-eddy simulation of turbulent flows in complex geometries is developed. In the present model, the subgrid-scale stress is decomposed into the modified Leonard stress, cross stress, and subgrid-scale Reynolds stress. The modified Leonard stress is explicitly computed assuming a scale similarity, while the cross stress and the subgrid-scale Reynolds stress are modeled using the global-coefficient eddy-viscosity model. The model coefficient is determined by a dynamic procedure based on the global-equilibrium between the subgrid-scale dissipation and the viscous dissipation. The new model relieves some of the difficulties associated with an eddy-viscosity closure, such as the nonalignment of the principal axes of the subgrid-scale stress tensor and the strain rate tensor and the anisotropy of turbulent flow fields, while, like other dynamic global-coefficient models, it does not require averaging or clipping of the model coefficient for numerical stabilization. The combination of the global-coefficient eddy-viscosity model and a scale-similarity model is demonstrated to produce improved predictions in a number of turbulent flow simulations

  2. Wall modeled large eddy simulations of complex high Reynolds number flows with synthetic inlet turbulence

    International Nuclear Information System (INIS)

    Patil, Sunil; Tafti, Danesh

    2012-01-01

    Highlights: ► Large eddy simulation. ► Wall layer modeling. ► Synthetic inlet turbulence. ► Swirl flows. - Abstract: Large eddy simulations of complex high Reynolds number flows are carried out with the near wall region being modeled with a zonal two layer model. A novel formulation for solving the turbulent boundary layer equation for the effective tangential velocity in a generalized co-ordinate system is presented and applied in the near wall zonal treatment. This formulation reduces the computational time in the inner layer significantly compared to the conventional two layer formulations present in the literature and is most suitable for complex geometries involving body fitted structured and unstructured meshes. The cost effectiveness and accuracy of the proposed wall model, used with the synthetic eddy method (SEM) to generate inlet turbulence, is investigated in turbulent channel flow, flow over a backward facing step, and confined swirling flows at moderately high Reynolds numbers. Predictions are compared with available DNS, experimental LDV data, as well as wall resolved LES. In all cases, there is at least an order of magnitude reduction in computational cost with no significant loss in prediction accuracy.

  3. An adaptive DES smodel that allows wall-resolved eddy simulation

    International Nuclear Information System (INIS)

    Yin, Zifei; Durbin, Paul A.

    2016-01-01

    Highlights: • A Detached Eddy Simulation model that mimics dynamic Smagorinsky formulation. • Adaptivity of model allows wall resolved eddy simulation on sufficient grids. • Ability to simulate natural and bypass transition is tested. - Abstract: A modification to the Adaptive-DES method of Yin et al. (2015) is proposed to improve its near-wall behavior. The modification is to the function (C_l_i_m) that imposes a lower limit on the dynamically evaluated coefficient (C_D_E_S). The modification allows Adaptive-DES to converge to wall-resolved eddy simulation, when grid resolution supports it. On coarse grids, or at high Reynolds number, it reverts to shielded DES — that is to DDES. The new formulation predicts results closer to wall-resolved LES than the previous formulation. It provides an ability to simulate transition: it is tested in both orderly and bypass transition. In fully turbulent, attached flow, the modification has little effect. Any improvement in predictions stem from better near-wall behavior of the adaptive method.

  4. Using an Electronic Highlighter to Eliminate the Negative Effects of Pre-Existing, Inappropriate Highlighting

    Science.gov (United States)

    Gier, Vicki; Kreiner, David; Hudnell, Jason; Montoya, Jodi; Herring, Daniel

    2011-01-01

    The purpose of the present experiment was to determine whether using an active learning technique, electronic highlighting, can eliminate the negative effects of pre-existing, poor highlighting on reading comprehension. Participants read passages containing no highlighting, appropriate highlighting, or inappropriate highlighting. We hypothesized…

  5. Large Eddy Simulation of the spray formation in confinements

    International Nuclear Information System (INIS)

    Lampa, A.; Fritsching, U.

    2013-01-01

    Highlights: • Process stability of confined spray processes is affected by the geometric design of the spray confinement. • LES simulations of confined spray flow have been performed successfully. • Clustering processes of droplets is predicted in simulations and validated with experiments. • Criteria for specific coherent gas flow patterns and droplet clustering behaviour are found. -- Abstract: The particle and powder properties produced within spray drying processes are influenced by various unsteady transport phenomena in the dispersed multiphase spray flow in a confined spray chamber. In this context differently scaled spray structures in a confined spray environment have been analyzed in experiments and numerical simulations. The experimental investigations have been carried out with Particle-Image-Velocimetry to determine the velocity of the gas and the discrete phase. Large-Eddy-Simulations have been set up to predict the transient behaviour of the spray process and have given more insight into the sensitivity of the spray flow structures in dependency from the spray chamber design

  6. Photon science 2012. Highlights and annual report

    International Nuclear Information System (INIS)

    Appel, Karen; Gehrke, Rainer; Gutt, Christian; Incoccia-Hermes, Lucia; Laarmann, Tim; Morgenroth, Wolfgang; Roehlsberger, Ralf; Schulte-Schrepping, Horst; Vainio, Ulla; Zimmermann, Martin von

    2012-12-01

    The synchrotron-radiation research at DESY is reviewed. The following topics are dealt with: Research highlights, research platforms and outstations, light sources, new technologies and developments. (HSI)

  7. Large eddy simulations of compressible magnetohydrodynamic turbulence

    International Nuclear Information System (INIS)

    Grete, Philipp

    2016-01-01

    Supersonic, magnetohydrodynamic (MHD) turbulence is thought to play an important role in many processes - especially in astrophysics, where detailed three-dimensional observations are scarce. Simulations can partially fill this gap and help to understand these processes. However, direct simulations with realistic parameters are often not feasible. Consequently, large eddy simulations (LES) have emerged as a viable alternative. In LES the overall complexity is reduced by simulating only large and intermediate scales directly. The smallest scales, usually referred to as subgrid-scales (SGS), are introduced to the simulation by means of an SGS model. Thus, the overall quality of an LES with respect to properly accounting for small-scale physics crucially depends on the quality of the SGS model. While there has been a lot of successful research on SGS models in the hydrodynamic regime for decades, SGS modeling in MHD is a rather recent topic, in particular, in the compressible regime. In this thesis, we derive and validate a new nonlinear MHD SGS model that explicitly takes compressibility effects into account. A filter is used to separate the large and intermediate scales, and it is thought to mimic finite resolution effects. In the derivation, we use a deconvolution approach on the filter kernel. With this approach, we are able to derive nonlinear closures for all SGS terms in MHD: the turbulent Reynolds and Maxwell stresses, and the turbulent electromotive force (EMF). We validate the new closures both a priori and a posteriori. In the a priori tests, we use high-resolution reference data of stationary, homogeneous, isotropic MHD turbulence to compare exact SGS quantities against predictions by the closures. The comparison includes, for example, correlations of turbulent fluxes, the average dissipative behavior, and alignment of SGS vectors such as the EMF. In order to quantify the performance of the new nonlinear closure, this comparison is conducted from the

  8. Large eddy simulation of cavitating flows

    Science.gov (United States)

    Gnanaskandan, Aswin; Mahesh, Krishnan

    2014-11-01

    Large eddy simulation on unstructured grids is used to study hydrodynamic cavitation. The multiphase medium is represented using a homogeneous equilibrium model that assumes thermal equilibrium between the liquid and the vapor phase. Surface tension effects are ignored and the governing equations are the compressible Navier Stokes equations for the liquid/vapor mixture along with a transport equation for the vapor mass fraction. A characteristic-based filtering scheme is developed to handle shocks and material discontinuities in non-ideal gases and mixtures. A TVD filter is applied as a corrector step in a predictor-corrector approach with the predictor scheme being non-dissipative and symmetric. The method is validated for canonical one dimensional flows and leading edge cavitation over a hydrofoil, and applied to study sheet to cloud cavitation over a wedge. This work is supported by the Office of Naval Research.

  9. Large eddy simulation of hydrodynamic cavitation

    Science.gov (United States)

    Bhatt, Mrugank; Mahesh, Krishnan

    2017-11-01

    Large eddy simulation is used to study sheet to cloud cavitation over a wedge. The mixture of water and water vapor is represented using a homogeneous mixture model. Compressible Navier-Stokes equations for mixture quantities along with transport equation for vapor mass fraction employing finite rate mass transfer between the two phases, are solved using the numerical method of Gnanaskandan and Mahesh. The method is implemented on unstructured grid with parallel MPI capabilities. Flow over a wedge is simulated at Re = 200 , 000 and the performance of the homogeneous mixture model is analyzed in predicting different regimes of sheet to cloud cavitation; namely, incipient, transitory and periodic, as observed in the experimental investigation of Harish et al.. This work is supported by the Office of Naval Research.

  10. Large-eddy simulation of contrails

    Energy Technology Data Exchange (ETDEWEB)

    Chlond, A [Max-Planck-Inst. fuer Meteorologie, Hamburg (Germany)

    1998-12-31

    A large eddy simulation (LES) model has been used to investigate the role of various external parameters and physical processes in the life-cycle of contrails. The model is applied to conditions that are typical for those under which contrails could be observed, i.e. in an atmosphere which is supersaturated with respect to ice and at a temperature of approximately 230 K or colder. The sensitivity runs indicate that the contrail evolution is controlled primarily by humidity, temperature and static stability of the ambient air and secondarily by the baroclinicity of the atmosphere. Moreover, it turns out that the initial ice particle concentration and radiative processes are of minor importance in the evolution of contrails at least during the 30 minutes simulation period. (author) 9 refs.

  11. Large eddy simulations of compressible magnetohydrodynamic turbulence

    Science.gov (United States)

    Grete, Philipp

    2017-02-01

    Supersonic, magnetohydrodynamic (MHD) turbulence is thought to play an important role in many processes - especially in astrophysics, where detailed three-dimensional observations are scarce. Simulations can partially fill this gap and help to understand these processes. However, direct simulations with realistic parameters are often not feasible. Consequently, large eddy simulations (LES) have emerged as a viable alternative. In LES the overall complexity is reduced by simulating only large and intermediate scales directly. The smallest scales, usually referred to as subgrid-scales (SGS), are introduced to the simulation by means of an SGS model. Thus, the overall quality of an LES with respect to properly accounting for small-scale physics crucially depends on the quality of the SGS model. While there has been a lot of successful research on SGS models in the hydrodynamic regime for decades, SGS modeling in MHD is a rather recent topic, in particular, in the compressible regime. In this thesis, we derive and validate a new nonlinear MHD SGS model that explicitly takes compressibility effects into account. A filter is used to separate the large and intermediate scales, and it is thought to mimic finite resolution effects. In the derivation, we use a deconvolution approach on the filter kernel. With this approach, we are able to derive nonlinear closures for all SGS terms in MHD: the turbulent Reynolds and Maxwell stresses, and the turbulent electromotive force (EMF). We validate the new closures both a priori and a posteriori. In the a priori tests, we use high-resolution reference data of stationary, homogeneous, isotropic MHD turbulence to compare exact SGS quantities against predictions by the closures. The comparison includes, for example, correlations of turbulent fluxes, the average dissipative behavior, and alignment of SGS vectors such as the EMF. In order to quantify the performance of the new nonlinear closure, this comparison is conducted from the

  12. Scaling relations for eddy current phenomena

    International Nuclear Information System (INIS)

    Dodd, C.V.; Deeds, W.E.

    1975-11-01

    Formulas are given for various electromagnetic quantities for coils in the presence of conductors, with the scaling parameters factored out so that small-scale model experiments can be related to large-scale apparatus. Particular emphasis is given to such quantities as eddy current heating, forces, power, and induced magnetic fields. For axially symmetric problems, closed-form integrals are available for the vector potential and all the other quantities obtainable from it. For unsymmetrical problems, a three-dimensional relaxation program can be used to obtain the vector potential and then the derivable quantities. Data on experimental measurements are given to verify the validity of the scaling laws for forces, inductances, and impedances. Indirectly these also support the validity of the scaling of the vector potential and all of the other quantities obtained from it

  13. Direct and large-eddy simulation IX

    CERN Document Server

    Kuerten, Hans; Geurts, Bernard; Armenio, Vincenzo

    2015-01-01

    This volume reflects the state of the art of numerical simulation of transitional and turbulent flows and provides an active forum for discussion of recent developments in simulation techniques and understanding of flow physics. Following the tradition of earlier DLES workshops, these papers address numerous theoretical and physical aspects of transitional and turbulent flows. At an applied level it contributes to the solution of problems related to energy production, transportation, magneto-hydrodynamics and the environment. A special session is devoted to quality issues of LES. The ninth Workshop on 'Direct and Large-Eddy Simulation' (DLES-9) was held in Dresden, April 3-5, 2013, organized by the Institute of Fluid Mechanics at Technische Universität Dresden. This book is of interest to scientists and engineers, both at an early level in their career and at more senior levels.

  14. Large eddy simulation of breaking waves

    DEFF Research Database (Denmark)

    Christensen, Erik Damgaard; Deigaard, Rolf

    2001-01-01

    A numerical model is used to simulate wave breaking, the large scale water motions and turbulence induced by the breaking process. The model consists of a free surface model using the surface markers method combined with a three-dimensional model that solves the flow equations. The turbulence....... The incoming waves are specified by a flux boundary condition. The waves are approaching in the shore-normal direction and are breaking on a plane, constant slope beach. The first few wave periods are simulated by a two-dimensional model in the vertical plane normal to the beach line. The model describes...... the steepening and the overturning of the wave. At a given instant, the model domain is extended to three dimensions, and the two-dimensional flow field develops spontaneously three-dimensional flow features with turbulent eddies. After a few wave periods, stationary (periodic) conditions are achieved...

  15. Eddy current technologies for thick metal structures

    International Nuclear Information System (INIS)

    Takagi, Toshiyuki; Endo, Hisashi

    2004-01-01

    One of approach of an eddy current testing (ECT) for thick metal structures is introduced. The detection limit of ECT is capable of enlarging thick more than 10 mm, which is ordinarily about 5 mm, by the design of probe. On the basis of results of numerical analysis, the defect detection in thick and shape is evaluated by the distribution of experimental ECT signals. The problems of ECT for thick metal structures and measures, approach to probe design, the specifications of probe, evaluation of experimental results and defect detection are described. By ECT fast simulator, good slit sharp is simulated in the case of 10 and 20 mm of EDM slit length and 5, 10 and 15 mm of slit height. (S.Y.)

  16. Large-eddy simulation of contrails

    Energy Technology Data Exchange (ETDEWEB)

    Chlond, A. [Max-Planck-Inst. fuer Meteorologie, Hamburg (Germany)

    1997-12-31

    A large eddy simulation (LES) model has been used to investigate the role of various external parameters and physical processes in the life-cycle of contrails. The model is applied to conditions that are typical for those under which contrails could be observed, i.e. in an atmosphere which is supersaturated with respect to ice and at a temperature of approximately 230 K or colder. The sensitivity runs indicate that the contrail evolution is controlled primarily by humidity, temperature and static stability of the ambient air and secondarily by the baroclinicity of the atmosphere. Moreover, it turns out that the initial ice particle concentration and radiative processes are of minor importance in the evolution of contrails at least during the 30 minutes simulation period. (author) 9 refs.

  17. Large eddy simulations of compressible magnetohydrodynamic turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Grete, Philipp

    2016-09-09

    Supersonic, magnetohydrodynamic (MHD) turbulence is thought to play an important role in many processes - especially in astrophysics, where detailed three-dimensional observations are scarce. Simulations can partially fill this gap and help to understand these processes. However, direct simulations with realistic parameters are often not feasible. Consequently, large eddy simulations (LES) have emerged as a viable alternative. In LES the overall complexity is reduced by simulating only large and intermediate scales directly. The smallest scales, usually referred to as subgrid-scales (SGS), are introduced to the simulation by means of an SGS model. Thus, the overall quality of an LES with respect to properly accounting for small-scale physics crucially depends on the quality of the SGS model. While there has been a lot of successful research on SGS models in the hydrodynamic regime for decades, SGS modeling in MHD is a rather recent topic, in particular, in the compressible regime. In this thesis, we derive and validate a new nonlinear MHD SGS model that explicitly takes compressibility effects into account. A filter is used to separate the large and intermediate scales, and it is thought to mimic finite resolution effects. In the derivation, we use a deconvolution approach on the filter kernel. With this approach, we are able to derive nonlinear closures for all SGS terms in MHD: the turbulent Reynolds and Maxwell stresses, and the turbulent electromotive force (EMF). We validate the new closures both a priori and a posteriori. In the a priori tests, we use high-resolution reference data of stationary, homogeneous, isotropic MHD turbulence to compare exact SGS quantities against predictions by the closures. The comparison includes, for example, correlations of turbulent fluxes, the average dissipative behavior, and alignment of SGS vectors such as the EMF. In order to quantify the performance of the new nonlinear closure, this comparison is conducted from the

  18. A comparison of the structure, properties, and water mass composition of quasi-isotropic eddies in western boundary currents in an eddy-resolving ocean model

    Science.gov (United States)

    Rykova, Tatiana; Oke, Peter R.; Griffin, David A.

    2017-06-01

    Using output from a near-global eddy-resolving ocean model, we analyse the properties and characteristics of quasi-isotropic eddies in five Western Boundary Current (WBC) regions, including the extensions of the Agulhas, East Australian Current (EAC), Brazil-Malvinas Confluence (BMC), Kuroshio and Gulf Stream regions. We assess the model eddies by comparing to satellite and in situ observations, and show that most aspects of the model's representation of eddies are realistic. We find that the mean eddies differ dramatically between these WBC regions - all with some unique and noteworthy characteristics. We find that the vertical displacement of isopycnals of Agulhas eddies is the greatest, averaging 350-450 m at depths of over 800-900 m. EAC (BMC) eddies are the least (most) barotropic, with only 50% (85-90%) of the velocity associated with the barotropic mode. Kuroshio eddies are the most stratified, resulting in small isopycnal displacement, even for strong eddies; and Gulf Stream eddies carry the most heat. Despite their differences, we explicitly show that the source waters for anticyclonic eddies are a mix of the WBC water (from the boundary current itself) and water that originates equatorward of the WBC eddy-field; and cyclonic eddies are a mix of WBC water and water that originates poleward of the WBC eddy-field.

  19. Eddy Correlation Flux Measurement System Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Cook, D. R. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-01

    The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration. The instruments used are: • a fast-response, three-dimensional (3D) wind sensor (sonic anemometer) to obtain the orthogonal wind components and the speed of sound (SOS) (used to derive the air temperature) • an open-path infrared gas analyzer (IRGA) to obtain the water vapor density and the CO2 concentration, and • an open-path infrared gas analyzer (IRGA) to obtain methane density and methane flux at one SGP EF and at the NSA CF. The ECOR systems are deployed at the locations where other methods for surface flux measurements (e.g., energy balance Bowen ratio [EBBR] systems) are difficult to employ, primarily at the north edge of a field of crops. A Surface Energy Balance System (SEBS) has been installed collocated with each deployed ECOR system in SGP, NSA, Tropical Western Pacific (TWP), ARM Mobile Facility 1 (AMF1), and ARM Mobile Facility 2 (AMF2). The surface energy balance system consists of upwelling and downwelling solar and infrared radiometers within one net radiometer, a wetness sensor, and soil measurements. The SEBS measurements allow the comparison of ECOR sensible and latent heat fluxes with the energy balance determined from the SEBS and provide information on wetting of the sensors for data quality purposes. The SEBS at one SGP and one NSA site also support upwelling and downwelling PAR measurements to qualify those two locations as Ameriflux sites.

  20. Editorial highlighting and highly cited papers

    Science.gov (United States)

    Antonoyiannakis, Manolis

    Editorial highlighting-the process whereby journal editors select, at the time of publication, a small subset of papers that are ostensibly of higher quality, importance or interest-is by now a widespread practice among major scientific journal publishers. Depending on the venue, and the extent to which editorial resources are invested in the process, highlighted papers appear as News & Views, Research Highlights, Perspectives, Editors' Choice, IOP Select, Editors' Summary, Spotlight on Optics, Editors' Picks, Viewpoints, Synopses, Editors' Suggestions, etc. Here, we look at the relation between highlighted papers and highly influential papers, which we define at two levels: having received enough citations to be among the (i) top few percent of their journal, and (ii) top 1% of all physics papers. Using multiple linear regression and multilevel regression modeling we examine the parameters associated with highly influential papers. We briefly comment on cause and effect relationships between citedness and highlighting of papers.

  1. Internal and forced eddy variability in the Labrador Sea

    Science.gov (United States)

    Bracco, A.; Luo, H.; Zhong, Y.; Lilly, J.

    2009-04-01

    Water mass transformation in the Labrador Sea, widely believed to be one of the key regions in the Atlantic Meridional Overturning Circulation (AMOC), now appears to be strongly impacted by vortex dynamics of the unstable boundary current. Large interannual variations in both eddy shedding and buoyancy transport from the boundary current have been observed but not explained, and are apparently sensitive to the state of the inflowing current. Heat and salinity fluxes associated with the eddies drive ventilation changes not accounted for by changes in local surface forcing, particularly during occasional years of extreme eddy activity, and constitute a predominant source of "internal" oceanic variability. The nature of this variable eddy-driven restratification is one of the outstanding questions along the northern transformation pathway. Here we investigate the eddy generation mechanism and the associated buoyancy fluxes by combining realistic and idealized numerical modeling, data analysis, and theory. Theory, supported by idealized experiments, provides criteria to test hypotheses as to the vortex formation process (by baroclinic instability linked to the bottom topography). Ensembles of numerical experiments with a high-resolution regional model (ROMS) allow for quantifying the sensitivity of eddy generation and property transport to variations in local and external forcing parameters. For the first time, we reproduce with a numerical simulation the observed interannual variability in the eddy kinetic energy in the convective region of the Labrador Basin and along the West Greenland Current.

  2. Eddy energy sources and flux in the Red Sea

    KAUST Repository

    Zhan, Peng

    2015-04-01

    In the Red Sea, eddies are reported to be one of the key features of hydrodynamics in the basin. They play a significant role in converting the energy among the large-scale circulation, the available potential energy (APE) and the eddy kinetic energy (EKE). Not only do eddies affect the horizontal circulation, deep-water formation and overturning circulation in the basin, but they also have a strong impact on the marine ecosystem by efficiently transporting heat, nutrients and carbon across the basin and by pumping the nutrient-enriched subsurface water to sustain the primary production. Previous observations and modeling work suggest that the Red Sea is rich of eddy activities. In this study, the eddy energy sources and sinks have been studied based on a high-resolution MITgcm. We have also investigated the possible mechanisms of eddy generation in the Red Sea. Eddies with high EKE are found more likely to appear in the central and northern Red Sea, with a significant seasonal variability. They are more inclined to occur during winter when they acquire their energy mainly from the conversion of APE. In winter, the central and especially the northern Red Sea are subject to important heat loss and extensive evaporation. The resultant densified upper-layer water tends to sink and release the APE through baroclinic instability, which is about one order larger than the barotropic instability contribution and is the largest source term for the EKE in the Red Sea. As a consequence, the eddy energy is confined to the upper layer but with a slope deepening from south to north. In summer, the positive surface heat flux helps maintain the stratification and impedes the gain of APE. The EKE is, therefore, much lower than that in winter despite a higher wind power input. Unlike many other seas, the wind energy is not the main source of energy to the eddies in the Red Sea.

  3. Investigating the computer analysis of eddy current NDT data

    International Nuclear Information System (INIS)

    Brown, R.L.

    1979-01-01

    The objective of this activity was to investigate and develop techniques for computer analysis of eddy current nondestructive testing (NDT) data. A single frequency commercial eddy current tester and a precision mechanical scanner were interfaced with a PDP-11/34 computer to obtain and analyze eddy current data from samples of 316 stainless steel tubing containing known discontinuities. Among the data analysis techniques investigated were: correlation, Fast Fourier Transforms (FFT), clustering, and Adaptive Learning Networks (ALN). The results were considered encouraging. ALN, for example, correctly identified 88% of the defects and non-defects from a group of 153 signal indications

  4. Eddy current analysis by the finite element circuit method

    International Nuclear Information System (INIS)

    Kameari, A.; Suzuki, Y.

    1977-01-01

    The analysis of the transient eddy current in the conductors by ''Finite Element Circuit Method'' is developed. This method can be easily applied to various geometrical shapes of thin conductors. The eddy currents on the vacuum vessel and the upper and lower support plates of JT-60 machine (which is now being constructed by Japan Atomic Energy Research Institute) are calculated by this method. The magnetic field induced by the eddy current is estimated in the domain occupied by the plasma. And the force exerted to the vacuum vessel is also estimated

  5. Using Highlighting to Train Attentional Expertise.

    Science.gov (United States)

    Roads, Brett; Mozer, Michael C; Busey, Thomas A

    2016-01-01

    Acquiring expertise in complex visual tasks is time consuming. To facilitate the efficient training of novices on where to look in these tasks, we propose an attentional highlighting paradigm. Highlighting involves dynamically modulating the saliency of a visual image to guide attention along the fixation path of a domain expert who had previously viewed the same image. In Experiment 1, we trained naive subjects via attentional highlighting on a fingerprint-matching task. Before and after training, we asked subjects to freely inspect images containing pairs of prints and determine whether the prints matched. Fixation sequences were automatically scored for the degree of expertise exhibited using a Bayesian discriminative model of novice and expert gaze behavior. Highlighted training causes gaze behavior to become more expert-like not only on the trained images but also on transfer images, indicating generalization of learning. In Experiment 2, to control for the possibility that the increase in expertise is due to mere exposure, we trained subjects via highlighting of fixation sequences from novices, not experts, and observed no transition toward expertise. In Experiment 3, to determine the specificity of the training effect, we trained subjects with expert fixation sequences from images other than the one being viewed, which preserves coarse-scale statistics of expert gaze but provides no information about fine-grain features. Observing at least a partial transition toward expertise, we obtain only weak evidence that the highlighting procedure facilitates the learning of critical local features. We discuss possible improvements to the highlighting procedure.

  6. AEB-highlights. January - June 1977

    International Nuclear Information System (INIS)

    1977-01-01

    AEB Highlights is a half-yearly report reflecting the most important recent achievements of the various Research and Technical divisions of the Atomic Energy Board. It appears alternatively in English and Afrikaans [af

  7. EDDY - a FORTRAN program to extract significant features from eddy-current test data - the basis of the CANSCAN system

    International Nuclear Information System (INIS)

    Jarvis, R.G.; Cranston, R.J.

    1982-09-01

    The FORTRAN program EDDY is designed to analyse data: from eddy-current scans of steam generator tubes. It is written in modular form, for future development, and it uses signal-recognition techniques that the authors developed in the profilometry of irradiated fuel elements. During a scan, significant signals are detected and extracted for immediate attention or more detailed analysis later. A version of the program was used in the CANSCAN system 'for automated eddy-current in-service inspection of nuclear steam generator tubing'

  8. Properties, Mechanisms and Predictability of Eddies in the Red Sea

    KAUST Repository

    Zhan, Peng

    2018-01-01

    of Red Sea eddies, including their temporal and spatial properties, their energy budget, the mechanisms of their evolution, and their predictability. Remote sensing data, in-situ observations, the oceanic general circulation model, and data assimilation

  9. Theoretical study of a flat eddy current probe

    International Nuclear Information System (INIS)

    Bouchard, A.; Dumont-Fillon, J.; Labbe, G.

    1976-01-01

    A mathematical model for the computation of the impedance of an eddy current probe has been determined in the case of flat product testing. Various applications are discussed with particular emphasis on ferromagnetic materials [fr

  10. IVA Ultrasonic and Eddy Current NDE for ISS

    Data.gov (United States)

    National Aeronautics and Space Administration — The project intends to develop a combined Ultrasonic and Eddy Current nondestructive evaluation (NDE) instrument for IVA use on ISS. A suite of IVA and EVA NDE...

  11. Eddy current testing probe with dual half-cylindrical coils

    Science.gov (United States)

    Bae, Byung-Hoon; Choi, Jung-Mi; Kim, Soo-Yong

    2000-02-01

    We have developed a new eddy current probe composed of a dual half-cylindrical (2HC) coil as an exciting coil and a sensing coil that is placed in the small gap of the 2HC coil. The 2HC coil induces a linear eddy current on the narrow region within the target medium. The magnitude of eddy current has a maximum peak with the narrow width, underneath the center of the exciting 2HC coil. Because of the linear eddy current, the probe can be used to detect not only the existence of a crack but also its direction in conducting materials. Using specimen with a machined crack, and varying the exciting frequency from 0.5 to 100 kHz, we investigated the relationships between the direction of crack and the output voltage of the sensing coil.

  12. Foam-machining tool with eddy-current transducer

    Science.gov (United States)

    Copper, W. P.

    1975-01-01

    Three-cutter machining system for foam-covered tanks incorporates eddy-current sensor. Sensor feeds signal to numerical controller which programs rotational and vertical axes of sensor travel, enabling cutterhead to profile around tank protrusions.

  13. An atmospheric electrical method to determine the eddy diffusion ...

    Indian Academy of Sciences (India)

    Keywords. Atmospheric electrical profiles; electrode layer; ion–aerosol balance equations. ... eddy diffusion theory (K-theory) in our model equations. K-theory is appropriate for near neutral ...... limit of strong turbulent mixing; J. Geophys. Res.

  14. Remote field eddy current testing of ferromagnetic tubes

    International Nuclear Information System (INIS)

    David, B.

    1990-01-01

    In order to test ferromagnetic tubes using internal probes, Intercontrole and the CEA have carried out theoretical and experimental works and developed a method to adapt the Remote Field Eddy Current technique which has been known and used for 30 years now. This document briefly recalls the basic principles of the Remote Field Eddy Current technique, the various steps of the works carried out and mainly describes examples of field inspection of ferromagnetic tubes and pipes [fr

  15. System for evaluating weld quality using eddy currents

    Science.gov (United States)

    Todorov, Evgueni I.; Hay, Jacob

    2017-12-12

    Electromagnetic and eddy current techniques for fast automated real-time and near real-time inspection and monitoring systems for high production rate joining processes. An eddy current system, array and method for the fast examination of welds to detect anomalies such as missed seam (MS) and lack of penetration (LOP) the system, array and methods capable of detecting and sizing surface and slightly subsurface flaws at various orientations in connection with at least the first and second weld pass.

  16. Large eddy simulation of premixed and non-premixed combustion

    OpenAIRE

    Malalasekera, W; Ibrahim, SS; Masri, AR; Sadasivuni, SK; Gubba, SR

    2010-01-01

    This paper summarises the authors experience in using the Large Eddy Simulation (LES) technique for the modelling of premixed and non-premixed combustion. The paper describes the application of LES based combustion modelling technique to two well defined experimental configurations where high quality data is available for validation. The large eddy simulation technique for the modelling flow and turbulence is based on the solution of governing equations for continuity and momentum in a struct...

  17. Using Highlighting to Train Attentional Expertise.

    Directory of Open Access Journals (Sweden)

    Brett Roads

    Full Text Available Acquiring expertise in complex visual tasks is time consuming. To facilitate the efficient training of novices on where to look in these tasks, we propose an attentional highlighting paradigm. Highlighting involves dynamically modulating the saliency of a visual image to guide attention along the fixation path of a domain expert who had previously viewed the same image. In Experiment 1, we trained naive subjects via attentional highlighting on a fingerprint-matching task. Before and after training, we asked subjects to freely inspect images containing pairs of prints and determine whether the prints matched. Fixation sequences were automatically scored for the degree of expertise exhibited using a Bayesian discriminative model of novice and expert gaze behavior. Highlighted training causes gaze behavior to become more expert-like not only on the trained images but also on transfer images, indicating generalization of learning. In Experiment 2, to control for the possibility that the increase in expertise is due to mere exposure, we trained subjects via highlighting of fixation sequences from novices, not experts, and observed no transition toward expertise. In Experiment 3, to determine the specificity of the training effect, we trained subjects with expert fixation sequences from images other than the one being viewed, which preserves coarse-scale statistics of expert gaze but provides no information about fine-grain features. Observing at least a partial transition toward expertise, we obtain only weak evidence that the highlighting procedure facilitates the learning of critical local features. We discuss possible improvements to the highlighting procedure.

  18. The role of eddy transports in climate change

    International Nuclear Information System (INIS)

    Stone, P.H.

    1994-01-01

    Large-scale atmospheric eddies are the dominant transport mechanisms in mid and high latitudes. Thus, climate models must simulate these eddies, their effects, and their feedbacks accurately. Getting the feedbacks right is particularly important since it is the feedbacks which affect climate sensitivity. Observational studies of these feedbacks are hindered by the lack of actual climate changes for which good data is available, and by the lack of data on vertical heat fluxes. General circulation model (GCM) studies are hindered by errors in GCM simulations of transports in the current climate; the dependence of GCM results on uncertain subgrid scale parameterizations; and large computational requirements. A more promising approach for learning about eddy feedbacks and how they can be modelled is process model studies. So far these studies have only looked at the feedback between eddy sensible heat fluxes arising from baroclinic instability and the temperature structure. The results indicate that there is a very strong negative feedback between eddy fluxes and temperature structure, both meridional and vertical, with the fluxes themselves being sensitive to small changes in temperature structure. These studies need to be extended to higher vertical resolution, and to include the effects of moisture, stationary eddies, and coupling to the oceans

  19. Large-eddy simulations for turbulent flows

    International Nuclear Information System (INIS)

    Husson, S.

    2007-07-01

    The aim of this work is to study the impact of thermal gradients on a turbulent channel flow with imposed wall temperatures and friction Reynolds numbers of 180 and 395. In this configuration, temperature variations can be strong and induce significant variations of the fluid properties. We consider the low Mach number equations and carry out large eddy simulations. We first validate our simulations thanks to comparisons of some of our LES results with DNS data. Then, we investigate the influence of the variations of the conductivity and the viscosity and show that we can assume these properties constant only for weak temperature gradients. We also study the thermal sub-grid-scale modelling and find no difference when the sub-grid-scale Prandtl number is taken constant or dynamically calculated. The analysis of the effects of strongly increasing the temperature ratio mainly shows a dissymmetry of the profiles. The physical mechanism responsible of these modifications is explained. Finally, we use semi-local scaling and the Van Driest transformation and we show that they lead to a better correspondence of the low and high temperature ratios profiles. (author)

  20. Dynamic large eddy simulation: Stability via realizability

    Science.gov (United States)

    Mokhtarpoor, Reza; Heinz, Stefan

    2017-10-01

    The concept of dynamic large eddy simulation (LES) is highly attractive: such methods can dynamically adjust to changing flow conditions, which is known to be highly beneficial. For example, this avoids the use of empirical, case dependent approximations (like damping functions). Ideally, dynamic LES should be local in physical space (without involving artificial clipping parameters), and it should be stable for a wide range of simulation time steps, Reynolds numbers, and numerical schemes. These properties are not trivial, but dynamic LES suffers from such problems over decades. We address these questions by performing dynamic LES of periodic hill flow including separation at a high Reynolds number Re = 37 000. For the case considered, the main result of our studies is that it is possible to design LES that has the desired properties. It requires physical consistency: a PDF-realizable and stress-realizable LES model, which requires the inclusion of the turbulent kinetic energy in the LES calculation. LES models that do not honor such physical consistency can become unstable. We do not find support for the previous assumption that long-term correlations of negative dynamic model parameters are responsible for instability. Instead, we concluded that instability is caused by the stable spatial organization of significant unphysical states, which are represented by wall-type gradient streaks of the standard deviation of the dynamic model parameter. The applicability of our realizability stabilization to other dynamic models (including the dynamic Smagorinsky model) is discussed.

  1. Large eddy simulation of stably stratified turbulence

    International Nuclear Information System (INIS)

    Shen Zhi; Zhang Zhaoshun; Cui Guixiang; Xu Chunxiao

    2011-01-01

    Stably stratified turbulence is a common phenomenon in atmosphere and ocean. In this paper the large eddy simulation is utilized for investigating homogeneous stably stratified turbulence numerically at Reynolds number Re = uL/v = 10 2 ∼10 3 and Froude number Fr = u/NL = 10 −2 ∼10 0 in which u is root mean square of velocity fluctuations, L is integral scale and N is Brunt-Vaïsälä frequency. Three sets of computation cases are designed with different initial conditions, namely isotropic turbulence, Taylor Green vortex and internal waves, to investigate the statistical properties from different origins. The computed horizontal and vertical energy spectra are consistent with observation in atmosphere and ocean when the composite parameter ReFr 2 is greater than O(1). It has also been found in this paper that the stratification turbulence can be developed under different initial velocity conditions and the internal wave energy is dominated in the developed stably stratified turbulence.

  2. Large Eddy Simulation of Heat Entrainment Under Arctic Sea Ice

    Science.gov (United States)

    Ramudu, Eshwan; Gelderloos, Renske; Yang, Di; Meneveau, Charles; Gnanadesikan, Anand

    2018-01-01

    Arctic sea ice has declined rapidly in recent decades. The faster than projected retreat suggests that free-running large-scale climate models may not be accurately representing some key processes. The small-scale turbulent entrainment of heat from the mixed layer could be one such process. To better understand this mechanism, we model the Arctic Ocean's Canada Basin, which is characterized by a perennial anomalously warm Pacific Summer Water (PSW) layer residing at the base of the mixed layer and a summertime Near-Surface Temperature Maximum (NSTM) within the mixed layer trapping heat from solar radiation. We use large eddy simulation (LES) to investigate heat entrainment for different ice-drift velocities and different initial temperature profiles. The value of LES is that the resolved turbulent fluxes are greater than the subgrid-scale fluxes for most of our parameter space. The results show that the presence of the NSTM enhances heat entrainment from the mixed layer. Additionally there is no PSW heat entrained under the parameter space considered. We propose a scaling law for the ocean-to-ice heat flux which depends on the initial temperature anomaly in the NSTM layer and the ice-drift velocity. A case study of "The Great Arctic Cyclone of 2012" gives a turbulent heat flux from the mixed layer that is approximately 70% of the total ocean-to-ice heat flux estimated from the PIOMAS model often used for short-term predictions. Present results highlight the need for large-scale climate models to account for the NSTM layer.

  3. Brookhaven highlights, October 1979-September 1980

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    Highlights are given for the research areas of the Brookhaven National Laboratory. These areas include high energy physics, physics and chemistry, life sciences, applied energy science (energy and environment, and nuclear energy), and support activities (including mathematics, instrumentation, reactors, and safety). (GHT)

  4. University of Maryland MRSEC - Research: Highlights

    Science.gov (United States)

    -Engineering Program: Project Lead the Way Thinking Small: Nanoscale Informal Science Education (NISE Education Outreach Highlights NanoFabulous Greatest Show on Earth: Big Top Physics, USA Science and Perspective at UMD MRSEC Nanoscience Camp Annual Middle School Student Science Conference (SSC) Pre

  5. Palliativedrugs.com therapeutic highlights: gabapentin

    Directory of Open Access Journals (Sweden)

    Twycross Robert

    2003-01-01

    Full Text Available This is the second in a series of highlights drawn from the www.palliativedrugs.com website. The website provides free access to the Palliative Care Formulary, a monthly newsletter and a bulletin board for advice to be given and received. With almost 10,000 professional members it is the largest palliative care resource of its kind.

  6. Brookhaven highlights, October 1979-September 1980

    International Nuclear Information System (INIS)

    1980-01-01

    Highlights are given for the research areas of the Brookhaven National Laboratory. These areas include high energy physics, physics and chemistry, life sciences, applied energy science (energy and environment, and nuclear energy), and support activities (including mathematics, instrumentation, reactors, and safety)

  7. Brookhaven highlights - Brookhaven National Laboratory 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-09-01

    This report highlights research conducted at Brookhaven National Laboratory in the following areas: alternating gradient synchrotron; physics; biology; national synchrotron light source; department of applied science; medical; chemistry; department of advanced technology; reactor; safety and environmental protection; instrumentation; and computing and communications.

  8. Vera C Rubin (1928–2016)

    Indian Academy of Sciences (India)

    she got out of the car and I got in, having fed the child (later children) and ... The DTM spectrograph was carried back and forth by truck between the two observatories, the ... in space, and using new digital imaging sensors were processed and ...

  9. Türgi valik / Barry Rubin

    Index Scriptorium Estoniae

    Rubin, Barry

    2007-01-01

    Õigluse ja Arengu Partei võit Türgi üldvalimistel tähendab, et Kemal Atatürgi 1920. aastatel ilmaliku riigina rajatud Türgi Vabariik on surnud, kuid ei tähenda siiski veel seda, et Türgist saaks islamimaa. Lisa: Presidendiotsing

  10. An eddy viscosity model for flow in a tube bundle

    International Nuclear Information System (INIS)

    Soussan, D.; Grandotto, M.

    1998-01-01

    The work described in this paper is part of the development of GENEPI a 3-dimensional finite element code, designed for the thermalhydraulic analysis of steam generators. It focuses on the implementation of two-phase flow turbulence-induced viscosity in a tube bundle. The GENEPI code, as other industrial codes, uses the eddy viscosity concept introduced by Boussinesq for single phase flow. The concept assumes that the turbulent momentum transfer is similar to the viscous shear stresses. Eddy viscosity formulation is reasonably well known for single phase flows, especially in simple geometries (i.e., in smooth tube, around a single body, or behind a row of bars/tubes), but there exists very little information on it for two-phase flows. An analogy between single and two-phases is used to set up a model for eddy viscosity. The eddy viscosity model examined in this paper is used for a tube bundle geometry and, therefore, is extended to include anisotropy to the classic model. Each of the main flow directions (cross flow inline, cross flow staggered, and parallel flows) gives rise to a specific eddy viscosity formula. The results from a parametric study indicate that the eddy viscosity in the staggered flow is roughly 1.5 times as large as that for the inline cross flow, 60 times as large as that for the parallel flow, and 105 as large as that for the molecular viscosity. Then, the different terms are combined with each other to result in a global eddy viscosity model for a steam generator tube bundle flow. (author)

  11. Eddy correlation measurements in wet environmental conditions

    Science.gov (United States)

    Cuenca, R. H.; Migliori, L.; O Kane, J. P.

    2003-04-01

    The lower Feale catchment is a low-lying peaty area of 200 km^2 situated in southwest Ireland that is subject to inundation by flooding. The catchment lies adjacent to the Feale River and is subject to tidal signals as well as runoff processes. Various mitigation strategies are being investigated to reduce the damage due to flooding. Part of the effort has required development of a detailed hydrologic balance for the study area which is a wet pasture environment with local field drains that are typically flooded. An eddy correlation system was installed in the summer of 2002 to measure components of the energy balance, including evapotranspiration, along with special sensors to measure other hydrologic variables particular to this study. Data collected will be essential for validation of surface flux models to be developed for this site. Data filtering is performed using a combination of software developed by the Boundary-Layer Group (BLG) at Oregon State University together with modifications made to this system for conditions at this site. This automated procedure greatly reduces the tedious inspection of individual records. The package of tests, developed by the BLG for both tower and aircraft high frequency data, checks for electronic spiking, signal dropout, unrealistic magnitudes, extreme higher moment statistics, as well as other error scenarios not covered by the instrumentation diagnostics built into the system. Critical parameter values for each potential error were developed by applying the tests to real fast response turbulent time series. Potential instrumentation problems, flux sampling problems, and unusual physical situations records are flagged for removal or further analysis. A final visual inspection step is required to minimize rejection of physically unusual but real behavior in the time series. The problems of data management, data quality control, individual instrumentation sensitivity, potential underestimation of latent and sensible heat

  12. Highlighting relatedness promotes prosocial motives and behavior.

    Science.gov (United States)

    Pavey, Louisa; Greitemeyer, Tobias; Sparks, Paul

    2011-07-01

    According to self-determination theory, people have three basic psychological needs: relatedness, competence, and autonomy. Of these, the authors reasoned that relatedness need satisfaction is particularly important for promoting prosocial behavior because of the increased sense of connectedness to others that this engenders. In Experiment 1, the authors manipulated relatedness, autonomy, competence, or gave participants a neutral task, and found that highlighting relatedness led to higher interest in volunteering and intentions to volunteer relative to the other conditions. Experiment 2 found that writing about relatedness experiences promoted feelings of connectedness to others, which in turn predicted greater prosocial intentions. Experiment 3 found that relatedness manipulation participants donated significantly more money to charity than did participants given a neutral task. The results suggest that highlighting relatedness increases engagement in prosocial activities and are discussed in relation to the conflict and compatibility between individual and social outcomes. © 2011 by the Society for Personality and Social Psychology, Inc

  13. Trends and highlights of VCI 2004

    CERN Document Server

    Fabjan, Christian Wolfgang

    2004-01-01

    This report attempts to summarize the presentations given at this conference. Topics related to R&D of gaseous and solid state detectors clearly point to several trends in particle physics instrumentation. More established techniques are represented by reports on recent experiments and facilities which can be considered the highlights in this research field. The extension of these techniques to space, arctic ice and deep sea are opening new frontiers of particle physics.

  14. Highlights of LHC experiments – Part I

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00072301; The ATLAS collaboration

    2017-01-01

    The superb performance of the LHC accelerator in 2016, in both live time and peak luminosity, has provided a large data sample of collisions at 13 TeV. Excellent performances of the ATLAS and LHCb detectors, together with highly performant offline and analysis systems, mean that a wealth of results are already available from 13 TeV data. Selected highlights are reported here.

  15. ENC 2010 European nuclear congress - Conference highlights

    Energy Technology Data Exchange (ETDEWEB)

    Bonin, B. [European Nuclear Society (ENS), Bern (Switzerland)

    2010-11-15

    This synthetical paper presents the main progress, trends or achievements that have appeared through the 450 communications of this conference. The highlights are reported according to 11 issues: 1) general nuclear situation and policy, 2) life extension, 3) standardisation, 4) safety, 5) fuel cycle, 6) dismantling techniques and waste management, 7) research reactors, 8) fusion, 9) nuclear applications in life sciences, 10) education and training, 11) networks and research structures

  16. Eddy-Kuroshio Interactions: Local and Remote Effects

    Science.gov (United States)

    Jan, Sen; Mensah, Vigan; Andres, Magdalena; Chang, Ming-Huei; Yang, Yiing Jang

    2017-12-01

    Quasi-geostrophic mesoscale eddies regularly impinge on the Kuroshio in the western North Pacific, but the processes underlying the evolution of these eddy-Kuroshio interactions have not yet been thoroughly investigated in the literature. Here this interaction is examined with results from a semi-idealized three-dimensional numerical model and observations from four pressure-sensor equipped inverted echo sounders (PIESs) in a zonal section east of Taiwan and satellite altimeters. Both the observations and numerical simulations suggest that, during the interaction of a cyclonic eddy with the Kuroshio, the circular eddy is deformed into an elliptic shape with the major axis in the northwest-southeast direction, before being dissipated; the poleward velocity and associated Kuroshio transport decrease and the sea level and pycnocline slopes across the Kuroshio weaken. In contrast, for an anticyclonic eddy during the eddy-Kuroshio interaction, variations in the velocity, sea level, and isopycnal depth are reversed; the circular eddy is also deformed to an ellipse but with the major axis parallel to the Kuroshio. The model results also demonstrate that the velocity field is modified first and consequently the SSH and isopycnal depth evolve during the interaction. Furthermore, due to the combined effect of impingement latitude and realistic topography, some eddy-Kuroshio interactions east of Taiwan are found to have remote effects, both in the Luzon Strait and on the East China Sea shelf northeast of Taiwan.Plain Language SummaryMesoscale eddies are everywhere in the ocean. These ocean swirls of either clockwise or counterclockwise spinning with diameter of about 100-300 km and rounding current speed of about 0.5 m/s, carrying energy and certain type of water mass, move westward and eventually reach the western boundary of each ocean. The evolution of these eddies and the interaction which occurs when they encounter the western boundary current, e.g. the Kuroshio in the

  17. Energy Cascade Analysis: from Subscale Eddies to Mean Flow

    Science.gov (United States)

    Cheikh, Mohamad Ibrahim; Wonnell, Louis; Chen, James

    2017-11-01

    Understanding the energy transfer between eddies and mean flow can provide insights into the energy cascade process. Much work has been done to investigate the energy cascade at the level of the smallest eddies using different numerical techniques derived from the Navier-Stokes equations. These methodologies, however, prove to be computationally inefficient when producing energy spectra for a wide range of length scales. In this regard, Morphing Continuum Theory (MCT) resolves the length-scales issues by assuming the fluid continuum to be composed of inner structures that play the role of subscale eddies. The current study show- cases the capabilities of MCT in capturing the dynamics of energy cascade at the level of subscale eddies, through a supersonic turbulent flow of Mach 2.93 over an 8× compression ramp. Analysis of the results using statistical averaging procedure shows the existence of a statistical coupling of the internal and translational kinetic energy fluctuations with the corresponding rotational kinetic energy of the subscale eddies, indicating a multiscale transfer of energy. The results show that MCT gives a new characterization of the energy cascade within compressible turbulence without the use of excessive computational resources. This material is based upon work supported by the Air Force Office of Scientific Research under Award Number FA9550-17-1-0154.

  18. Eddy correlation measurements of oxygen uptake in deep ocean sediments

    DEFF Research Database (Denmark)

    Berg, P.; Glud, Ronnie Nøhr; Hume, A.

    2010-01-01

    .62 +/- 0.23 (SE, n = 7), 1.65 +/- 0.33 (n = 2), and 1.43 +/- 0.15 (n = 25) mmol m(-2) d(-1). The very good agreement between the eddy correlation flux and the chamber flux serves as a new, important validation of the eddy correlation technique. It demonstrates that the eddy correlation instrumentation......Abstract: We present and compare small sediment-water fluxes of O-2 determined with the eddy correlation technique, with in situ chambers, and from vertical sediment microprofiles at a 1450 m deep-ocean site in Sagami Bay, Japan. The average O-2 uptake for the three approaches, respectively, was 1...... available today is precise and can resolve accurately even very small benthic O-2 fluxes. The correlated fluctuations in vertical velocity and O-2 concentration that give the eddy flux had average values of 0.074 cm s(-1) and 0.049 mu M. The latter represents only 0.08% of the 59 mu M mean O-2 concentration...

  19. The eddy kinetic energy budget in the Red Sea

    KAUST Repository

    Zhan, Peng

    2016-06-09

    The budget of eddy kinetic energy (EKE) in the Red Sea, including the sources, redistributions and sink, is examined using a high-resolution eddy-resolving ocean circulation model. A pronounced seasonally varying EKE is identified, with its maximum intensity occurring in winter, and the strongest EKE is captured mainly in the central and northern basins within the upper 200 m. Eddies acquire kinetic energy from conversion of eddy available potential energy (EPE), from transfer of mean kinetic energy (MKE), and from direct generation due to time-varying (turbulent) wind stress, the first of which contributes predominantly to the majority of the EKE. The EPE-to-EKE conversion occurs almost in the entire basin, while the MKE-to-EKE transfer appears mainly along the shelf boundary of the basin (200 miso-bath) where high horizontal shear interacts with topography. The EKE generated by the turbulent wind stress is relatively small and limited to the southern basin. All these processes are intensified during winter, when the rate of energy conversion is about four to five times larger than that in summer. The EKE is redistributed by the vertical and horizontal divergence of energy flux and the advection of the mean flow. As a main sink of EKE, dissipation processes is ubiquitously found in the basin. The seasonal variability of these energy conversion terms can explain the significant seasonality of eddy activities in the Red Sea. This article is protected by copyright. All rights reserved.

  20. Eddy Current Sensing of Torque in Rotating Shafts

    Science.gov (United States)

    Varonis, Orestes J.; Ida, Nathan

    2013-12-01

    The noncontact torque sensing in machine shafts is addressed based on the stress induced in a press-fitted magnetoelastic sleeve on the shaft and eddy current sensing of the changes of electrical conductivity and magnetic permeability due to the presence of stress. The eddy current probe uses dual drive, dual sensing coils whose purpose is increased sensitivity to torque and decreased sensitivity to variations in distance between probe and shaft (liftoff). A mechanism of keeping the distance constant is also employed. Both the probe and the magnetoelastic sleeve are evaluated for performance using a standard eddy current instrument. An eddy current instrument is also used to drive the coils and analyze the torque data. The method and sensor described are general and adaptable to a variety of applications. The sensor is suitable for static and rotating shafts, is independent of shaft diameter and operational over a large range of torques. The torque sensor uses a differential eddy current measurement resulting in cancellation of common mode effects including temperature and vibrations.

  1. Statistical Characteristics of Mesoscale Eddies in the North Pacific Derived from Satellite Altimetry

    Directory of Open Access Journals (Sweden)

    Yu-Hsin Cheng

    2014-06-01

    Full Text Available The sea level anomaly data derived from satellite altimetry are analyzed to investigate statistical characteristics of mesoscale eddies in the North Pacific. Eddies are detected by a free-threshold eddy identification algorithm. The results show that the distributions of size, amplitude, propagation speed, and eddy kinetic energy of eddy follow the Rayleigh distribution. The most active regions of eddies are the Kuroshio Extension region, the Subtropical Counter Current zone, and the Northeastern Tropical Pacific region. By contrast, eddies are seldom observed around the center of the eastern part of the North Pacific Subarctic Gyre. The propagation speed and kinetic energy of cyclonic and anticyclonic eddies are almost the same, but anticyclonic eddies possess greater lifespans, sizes, and amplitudes than those of cyclonic eddies. Most eddies in the North Pacific propagate westward except in the Oyashio region. Around the northeastern tropical Pacific and the California currents, cyclonic and anticyclonic eddies propagate westward with slightly equatorward (197° average azimuth relative to east and poleward (165° deflection, respectively. This implies that the background current may play an important role in formation of the eddy pathway patterns.

  2. A Coherent vorticity preserving eddy-viscosity correction for Large-Eddy Simulation

    Science.gov (United States)

    Chapelier, J.-B.; Wasistho, B.; Scalo, C.

    2018-04-01

    This paper introduces a new approach to Large-Eddy Simulation (LES) where subgrid-scale (SGS) dissipation is applied proportionally to the degree of local spectral broadening, hence mitigated or deactivated in regions dominated by large-scale and/or laminar vortical motion. The proposed coherent-vorticity preserving (CvP) LES methodology is based on the evaluation of the ratio of the test-filtered to resolved (or grid-filtered) enstrophy, σ. Values of σ close to 1 indicate low sub-test-filter turbulent activity, justifying local deactivation of the SGS dissipation. The intensity of the SGS dissipation is progressively increased for σ activated in developed turbulence characterized by σ ≤σeq, where the value σeq is derived assuming a Kolmogorov spectrum. The proposed approach can be applied to any eddy-viscosity model, is algorithmically simple and computationally inexpensive. LES of Taylor-Green vortex breakdown demonstrates that the CvP methodology improves the performance of traditional, non-dynamic dissipative SGS models, capturing the peak of total turbulent kinetic energy dissipation during transition. Similar accuracy is obtained by adopting Germano's dynamic procedure albeit at more than twice the computational overhead. A CvP-LES of a pair of unstable periodic helical vortices is shown to predict accurately the experimentally observed growth rate using coarse resolutions. The ability of the CvP methodology to dynamically sort the coherent, large-scale motion from the smaller, broadband scales during transition is demonstrated via flow visualizations. LES of compressible channel are carried out and show a good match with a reference DNS.

  3. Highlights and Perspectives from the CMS Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Butler, Joel Nathan [Fermilab

    2017-09-09

    In 2016, the Large Hadron Collider provided proton-proton collisions at 13 TeV center-of-mass energy and achieved very high luminosity and reliability. The performance of the CMS Experiment in this running period and a selection of recent physics results are presented. These include precision measurements and searches for new particles. The status and prospects for data-taking in 2017 and a brief summary of the highlights of the High Luminosity (HL-LHC) upgrade of the CMS detector are also presented.

  4. Fermi GBM: Highlights from the First Year

    Science.gov (United States)

    Wilson-Hodge, Colleen A.

    2009-01-01

    The Fermi Gamma ray Burst Monitor is an all-sky instrument sensitive to photons from about 8 keV to 40 MeV. I will summarize highlights from the first year, including triggered observations of gamma ray bursts, soft gamma ray repeaters, and terrestrial gamma flashes, and observations in the continuous data of X-ray binaries and accreting X-ray pulsars. GBM provides complementary observations to Swift/BAT, observing many of the same sources, but over a wider energy range.

  5. Highlights of the SSC Site Development Plan

    International Nuclear Information System (INIS)

    Sanford, J.R.

    1991-10-01

    This paper summarizes highlights of the Site Development Plan for the Superconducting Super Collider Laboratory. The Plan, sometimes called a Master Plan, was prepared by the architectural and engineering firm for the Laboratory: Parsons Brinckerhoff/Morrison Knudsen (PB/MK) working in association with CRSS. Their task was to interpret the SSC project needs in the context of the Ellis County, Texas site. The team effort was under the direction of Lewis May from CRSS, guided by Robert Sims from the SSC Laboratory. Conceptual drawings are presented in this report

  6. Some physics highlights from the EUROBALL spectrometer

    International Nuclear Information System (INIS)

    Korten, W.

    2004-01-01

    The latest generation of large γ-ray spectrometers, such as EUROBALL, has boosted the explorations of nuclei under extreme conditions especially at the limits of angular momentum and at finite temperatures. But the coupling of this instrument to very selective ''ancillary'' devices allows for more and more refined investigations of the third important degree of freedom in contemporary nuclear-structure studies, the isospin. This contribution summarises some of the recent highlights from the physics at EUROBALL obtained in some of the different areas of nuclear-structure research

  7. Physics highlights at ILC and CLIC

    CERN Document Server

    Lukić, Strahinja

    2015-01-01

    In this lecture, the physics potential for the e+e- linear collider experiments ILC and CLIC is reviewed. The experimental conditions are compared to those at hadron colliders and their intrinsic value for precision experiments, complementary to the hadron colliders, is discussed. The detector concepts for ILC and CLIC are outlined in their most important aspects related to the precision physics. Highlights from the physics program and from the benchmark studies are given. It is shown that linear colliders are a promising tool, complementing the LHC in essential ways to test the Standard Model and to search for new physics.

  8. Non-Destructive Techniques Based on Eddy Current Testing

    Science.gov (United States)

    García-Martín, Javier; Gómez-Gil, Jaime; Vázquez-Sánchez, Ernesto

    2011-01-01

    Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. This paper includes an overview of the fundamentals and main variables of eddy current testing. It also describes the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems. Recent advances in complex models towards solving crack-sensor interaction, developments in instrumentation due to advances in electronic devices, and the evolution of data processing suggest that eddy current testing systems will be increasingly used in the future. PMID:22163754

  9. Investigation on a new inducer of pulsed eddy current thermography

    Directory of Open Access Journals (Sweden)

    Min He

    2016-09-01

    Full Text Available In this paper, a new inducer of pulsed eddy current thermography (PECT is presented. The use of the inducer can help avoid the problem of blocking the infrared (IR camera’s view in eddy current thermography technique. The inducer can also provide even heating of the test specimen. This paper is concerned with the temperature distribution law around the crack on a specimen when utilizing the new inducer. Firstly, relative mathematical models are provided. In the following section, eddy current distribution and temperature distribution around the crack are studied using the numerical simulation method. The best separation distance between the inducer and the specimen is also determined. Then, results of temperature distribution around the crack stimulated by the inducer are gained by experiments. Effect of current value on temperature rise is studied as well in the experiments. Based on temperature data, temperature features of the crack are discussed.

  10. EFFICIENCY OF METAL SCRAP SEPARATION IN EDDY CURRENT SEPARATOR

    Directory of Open Access Journals (Sweden)

    Gordan Bedeković

    2008-11-01

    Full Text Available Eddy-current separation is most often method used for the recovery of non-ferrous metals (Al, Cu, Zn, Pb from solid wastes and also for separating non-ferrous metals from each other. The feed material comes to rotary drum and magnetic field by belt conveyer. The changing magnetic field induce eddy currents in conductive (metallic particles. Because interaction between this currents and the magnetic field electrodynamic forces will act on conductive particles. Therefore the trajectories of conductive particles will be different from the trajectories of the non-conductive ones. Separation is a result of the combined actions of several forces (electrodynamic, gravitational and frictional. The paper presents results of aluminium recovery from mixture of metallic particles in eddy current separator. Testing were conducted under field condition. Results shows that is possible achieve recovery of 99 % and concentrate quality of 89 % of aluminium (the paper is published in Croatian.

  11. Detection of Northern Hemisphere transient eddies at Gale Crater Mars

    Science.gov (United States)

    Haberle, Robert M.; Juárez, Manuel de la Torre; Kahre, Melinda A.; Kass, David M.; Barnes, Jeffrey R.; Hollingsworth, Jeffery L.; Harri, Ari-Matti; Kahanpää, Henrik

    2018-06-01

    The Rover Environmental Monitoring Station (REMS) on the Curiosity Rover is operating in the Southern Hemisphere of Mars and is detecting synoptic period oscillations in the pressure data that we attribute to Northern Hemisphere transient eddies. We base this interpretation on the similarity in the periods of the eddies and their seasonal variations with those observed in northern midlatitudes by Viking Lander 2 (VL-2) 18 Mars years earlier. Further support for this interpretation comes from global circulation modeling which shows similar behavior in the transient eddies at the grid points closest to Curiosity and VL-2. These observations provide the first in situ evidence that the frontal systems often associated with "Flushing Dust Storms" do cross the equator and extend into the Southern Hemisphere.

  12. Eddy Current Testing for Detecting Small Defects in Thin Films

    Science.gov (United States)

    Obeid, Simon; Tranjan, Farid M.; Dogaru, Teodor

    2007-03-01

    Presented here is a technique of using Eddy Current based Giant Magneto-Resistance sensor (GMR) to detect surface and sub-layered minute defects in thin films. For surface crack detection, a measurement was performed on a copper metallization of 5-10 microns thick. It was done by scanning the GMR sensor on the surface of the wafer that had two scratches of 0.2 mm, and 2.5 mm in length respectively. In another experiment, metal coatings were deposited over the layers containing five defects with known lengths such that the defects were invisible from the surface. The limit of detection (resolution), in terms of defect size, of the GMR high-resolution Eddy Current probe was studied using this sample. Applications of Eddy Current testing include detecting defects in thin film metallic layers, and quality control of metallization layers on silicon wafers for integrated circuits manufacturing.

  13. The relationship between a deformation-based eddy parameterization and the LANS-α turbulence model

    Science.gov (United States)

    Bachman, Scott D.; Anstey, James A.; Zanna, Laure

    2018-06-01

    A recent class of ocean eddy parameterizations proposed by Porta Mana and Zanna (2014) and Anstey and Zanna (2017) modeled the large-scale flow as a non-Newtonian fluid whose subgridscale eddy stress is a nonlinear function of the deformation. This idea, while largely new to ocean modeling, has a history in turbulence modeling dating at least back to Rivlin (1957). The new class of parameterizations results in equations that resemble the Lagrangian-averaged Navier-Stokes-α model (LANS-α, e.g., Holm et al., 1998a). In this note we employ basic tensor mathematics to highlight the similarities between these turbulence models using component-free notation. We extend the Anstey and Zanna (2017) parameterization, which was originally presented in 2D, to 3D, and derive variants of this closure that arise when the full non-Newtonian stress tensor is used. Despite the mathematical similarities between the non-Newtonian and LANS-α models which might provide insight into numerical implementation, the input and dissipation of kinetic energy between these two turbulent models differ.

  14. Large-eddy simulations of the non-reactive flow in the Sydney swirl burner

    International Nuclear Information System (INIS)

    Yang Yang; Kær, Søren Knudsen

    2012-01-01

    Highlights: ► Rational mesh and grid system for LES are discussed. ► Validated results are provided and discrepancy of mean radial velocity component is discussed. ► Flow structures are identified using vorticity field. ► We performed POD on cross sections to assist in understanding of coherent structures. - Abstract: This paper presents a numerical investigation using large-eddy simulation. Two isothermal cases from the Sydney swirling flame database with different swirl numbers were tested. Rational grid system and mesh details were presented firstly. Validations showed overall good agreement in time averaged results. In medium swirling case, there are two reverse-flow regions with a collar-like structure between them. The existence of strong unsteady structure, precessing vortex core, was proven. Coherent structures are detached from the instantaneous field. Q-criterion was used to visualize vorticity field with distinct clear structure of vortice tubes. Dominating spatial–temporal structures contained in different cross sections were extracted using proper orthogonal decomposition. In high swirling case, there is only one long reverse-flow region. In this paper, we proved the capability of a commercial CFD package in predicting complex flow field and presented the potential of large eddy simulation in understanding dynamics.

  15. An Examination of Parameters Affecting Large Eddy Simulations of Flow Past a Square Cylinder

    Science.gov (United States)

    Mankbadi, M. R.; Georgiadis, N. J.

    2014-01-01

    Separated flow over a bluff body is analyzed via large eddy simulations. The turbulent flow around a square cylinder features a variety of complex flow phenomena such as highly unsteady vortical structures, reverse flow in the near wall region, and wake turbulence. The formation of spanwise vortices is often times artificially suppressed in computations by either insufficient depth or a coarse spanwise resolution. As the resolution is refined and the domain extended, the artificial turbulent energy exchange between spanwise and streamwise turbulence is eliminated within the wake region. A parametric study is performed highlighting the effects of spanwise vortices where the spanwise computational domain's resolution and depth are varied. For Re=22,000, the mean and turbulent statistics computed from the numerical large eddy simulations (NLES) are in good agreement with experimental data. Von-Karman shedding is observed in the wake of the cylinder. Mesh independence is illustrated by comparing a mesh resolution of 2 million to 16 million. Sensitivities to time stepping were minimized and sampling frequency sensitivities were nonpresent. While increasing the spanwise depth and resolution can be costly, this practice was found to be necessary to eliminating the artificial turbulent energy exchange.

  16. Large eddy simulations of isothermal confined swirling flow in an industrial gas-turbine

    International Nuclear Information System (INIS)

    Bulat, G.; Jones, W.P.; Navarro-Martinez, S.

    2015-01-01

    Highlights: • We conduct a large eddy simulation of an industrial gas turbine. • The results are compared with measurements obtained under isothermal conditions. • The method reproduces the observed precessing vortex and central vortex cores. • The profiles of mean and rms velocities are found to be captured to a good accuracy. - Abstract: The paper describes the results of a computational study of the strongly swirling isothermal flow in the combustion chamber of an industrial gas turbine. The flow field characteristics are computed using large eddy simulation in conjunction with a dynamic version of the Smagorinsky model for the sub-grid-scale stresses. Grid refinement studies demonstrate that the results are essentially grid independent. The LES results are compared with an extensive set of measurements and the agreement with these is overall good. The method is shown to be capable of reproducing the observed precessing vortex and central vortex cores and the profiles of mean and rms velocities are found to be captured to a good accuracy. The overall flow structure is shown to be virtually independent of Reynolds number

  17. Developing an Automated Method for Detection of Operationally Relevant Ocean Fronts and Eddies

    Science.gov (United States)

    Rogers-Cotrone, J. D.; Cadden, D. D. H.; Rivera, P.; Wynn, L. L.

    2016-02-01

    Since the early 90's, the U.S. Navy has utilized an observation-based process for identification of frontal systems and eddies. These Ocean Feature Assessments (OFA) rely on trained analysts to identify and position ocean features using satellite-observed sea surface temperatures. Meanwhile, as enhancements and expansion of the navy's Hybrid Coastal Ocean Model (HYCOM) and Regional Navy Coastal Ocean Model (RNCOM) domains have proceeded, the Naval Oceanographic Office (NAVO) has provided Tactical Oceanographic Feature Assessments (TOFA) that are based on data-validated model output but also rely on analyst identification of significant features. A recently completed project has migrated OFA production to the ArcGIS-based Acoustic Reach-back Cell Ocean Analysis Suite (ARCOAS), enabling use of additional observational datasets and significantly decreasing production time; however, it has highlighted inconsistencies inherent to this analyst-based identification process. Current efforts are focused on development of an automated method for detecting operationally significant fronts and eddies that integrates model output and observational data on a global scale. Previous attempts to employ techniques from the scientific community have been unable to meet the production tempo at NAVO. Thus, a system that incorporates existing techniques (Marr-Hildreth, Okubo-Weiss, etc.) with internally-developed feature identification methods (from model-derived physical and acoustic properties) is required. Ongoing expansions to the ARCOAS toolset have shown promising early results.

  18. Observation of baroclinic eddies southeast of Okinawa Island

    Institute of Scientific and Technical Information of China (English)

    PARK; Jae-Hun

    2008-01-01

    In the region southeast of Okinawa, during May to July 2001, a cyclonic and an anticyclonic eddy were observed from combined measurements of hydrocasts, an upward-looking moored acoustic Doppler current profiler (MADCP), pressure-recording inverted echo sounders (PIESs), satellite altimetry, and a coastal tide gauge. The hydrographic data showed that the lowest/highest temperature (T) and salinity (S) anomalies from a 13-year mean for the same season were respectively -3.0/+2.5℃ and -0.20/+0.15 psu at 380/500 dbar for the cyclonic/anticyclonic eddies. From the PIES data, using a gravest empirical mode method, we estimated time-varying surface dynamic height (D) anomaly referred to 2000 dbar changing from -20 to 30 cm, and time-varying T and S anomalies at 500 dbar ranging through about ±2 ℃ and ±0.2 psu, respectively. The passage of the eddies caused variations of both satellite-measured sea surface height anomaly (SSHA) and tide-gauge-measured sea level anomaly to change from about –20 to 30 cm, consistent with the D anomaly from the PIESs. Bottom pressure sensors measured no variation related to these eddy activities, which indicated that the two eddies were dominated by baro-clinicity. Time series of SSHA map confirmed that the two eddies, originating from the North Pacific Subtropical Countercurrent region near 20°―30°N and 150°―160°E, traveled about 3000 km for about 18 months with mean westward propagation speed of about 6 cm/s, before arriving at the region southeast of Okinawa Island.

  19. Eddy turbulence parameters inferred from radar observations at Jicamarca

    Directory of Open Access Journals (Sweden)

    M. N. Vlasov

    2007-03-01

    Full Text Available Significant electron density striations, neutral temperatures 27 K above nominal, and intense wind shear were observed in the E-region ionosphere over the Jicamarca Radio Observatory during an unusual event on 26 July 2005 (Hysell et al., 2007. In this paper, these results are used to estimate eddy turbulence parameters and their effects. Models for the thermal balance in the mesosphere/lower thermosphere and the charged particle density in the E region are developed here. The thermal balance model includes eddy conduction and viscous dissipation of turbulent energy as well as cooling by infrared radiation. The production and recombination of ions and electrons in the E region, together with the production and transport of nitric oxide, are included in the plasma density model. Good agreement between the model results and the experimental data is obtained for an eddy diffusion coefficient of about 1×103 m2/s at its peak, which occurs at an altitude of 107 km. This eddy turbulence results in a local maximum of the temperature in the upper mesosphere/lower thermosphere and could correspond either to an unusually high mesopause or to a double mesosphere. Although complicated by plasma dynamic effects and ongoing controversy, our interpretation of Farley-Buneman wave phase velocity (Hysell et al., 2007 is consistent with a low Brunt-Väisälä frequency in the region of interest. Nitric oxide transport due to eddy diffusion from the lower thermosphere to the mesosphere causes electron density changes in the E region whereas NO density modulation due to irregularities in the eddy diffusion coefficient creates variability in the electron density.

  20. Eddy turbulence parameters inferred from radar observations at Jicamarca

    Directory of Open Access Journals (Sweden)

    M. N. Vlasov

    2007-03-01

    Full Text Available Significant electron density striations, neutral temperatures 27 K above nominal, and intense wind shear were observed in the E-region ionosphere over the Jicamarca Radio Observatory during an unusual event on 26 July 2005 (Hysell et al., 2007. In this paper, these results are used to estimate eddy turbulence parameters and their effects. Models for the thermal balance in the mesosphere/lower thermosphere and the charged particle density in the E region are developed here. The thermal balance model includes eddy conduction and viscous dissipation of turbulent energy as well as cooling by infrared radiation. The production and recombination of ions and electrons in the E region, together with the production and transport of nitric oxide, are included in the plasma density model. Good agreement between the model results and the experimental data is obtained for an eddy diffusion coefficient of about 1×103 m2/s at its peak, which occurs at an altitude of 107 km. This eddy turbulence results in a local maximum of the temperature in the upper mesosphere/lower thermosphere and could correspond either to an unusually high mesopause or to a double mesosphere. Although complicated by plasma dynamic effects and ongoing controversy, our interpretation of Farley-Buneman wave phase velocity (Hysell et al., 2007 is consistent with a low Brunt-Väisälä frequency in the region of interest. Nitric oxide transport due to eddy diffusion from the lower thermosphere to the mesosphere causes electron density changes in the E region whereas NO density modulation due to irregularities in the eddy diffusion coefficient creates variability in the electron density.

  1. Sizing Performance of the Newly Developed Eddy Current System

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Chan Hee; Lee, Hee Jong; Yoo, Hyun Ju; Moon, Gyoon Young; Lee, Tae Hoon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

    2013-10-15

    This paper describes the comparison results of sizing performance for two systems. The KHNP developed a new eddy current testing system for the inspection of steam generator tubing in domestic nuclear power plants. The equivalency assessment of the newly developed system with the EPRI-qualified system was already carried out. In this paper, the comparisons of depth-sizing performance for the artificial flaws between two systems were performed. The results show that the newly developed system is in good agreement with the qualified system. Therefore, it is expected that the newly developed eddy current system can be used for the inspection of steam generator tubing in nuclear power plants. There are some non-destructive examination (NDE) methods for the inspection of components in nuclear power plants, such as ultrasonic, radiographic, eddy current testing, etc. The eddy current testing is widely used for the inspection of steam generator (SG) tubing because it offers a relatively low cost approach for high speed, large scale testing of metallic materials in high pressure and temperature engineering systems. The Korea Hydro and Nuclear Power Co., Ltd. (KHNP) developed an eddy current testing system for the inspection of steam generator tubing in nuclear power plants. This system includes not only hardware but software such as the frequency generator and data acquisition-analysis program. The foreign eddy current system developed by ZETEC is currently used for the inspection of steam generator tubing in domestic nuclear power plants. The equivalency assessment between two systems was already carried out in accordance with the EPRI steam generator examination guidelines.

  2. Biotransformation and bioactivation reactions - 2015 literature highlights.

    Science.gov (United States)

    Baillie, Thomas A; Dalvie, Deepak; Rietjens, Ivonne M C M; Cyrus Khojasteh, S

    2016-05-01

    Since 1972, Drug Metabolism Reviews has been recognized as one of the principal resources for researchers in pharmacological, pharmaceutical and toxicological fields to keep abreast of advances in drug metabolism science in academia and the pharmaceutical industry. With a distinguished list of authors and editors, the journal covers topics ranging from relatively mature fields, such as cytochrome P450 enzymes, to a variety of emerging fields. We hope to continue this tradition with the current compendium of mini-reviews that highlight novel biotransformation processes that were published during the past year. Each review begins with a summary of the article followed by our comments on novel aspects of the research and their biological implications. This collection of highlights is not intended to be exhaustive, but rather to be illustrative of recent research that provides new insights or approaches that advance the field of drug metabolism. Abbreviations NAPQI N-acetyl-p-benzoquinoneimine ALDH aldehyde dehydrogenase AO aldehyde oxidase AKR aldo-keto reductase CES carboxylesterase CSB cystathionine β-synthase CSE cystathionine γ-lyase P450 cytochrome P450 DHPO 2,3-dihydropyridin-4-one ESI electrospray FMO flavin monooxygenase GSH glutathione GSSG glutathione disulfide ICPMS inductively coupled plasma mass spectrometry i.p. intraperitoneal MDR multidrug-resistant NNAL 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol NNK 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone oaTOF orthogonal acceleration time-of-flight PBK physiologically based kinetic PCP pentachlorophenol SDR short-chain dehydrogenase/reductase SULT sulfotransferase TB tuberculosis.

  3. Syndicate of renewable energies - Highlights 2015

    International Nuclear Information System (INIS)

    2016-01-01

    This publication first proposes a presentation of the SER (Syndicat des Energies Renouvelables, Syndicate of Renewable Energies), a professional body: missions, scope of action, members. It outlines its commitment in the French policy for energy transition as a major actor of the sector of renewable energies. It addresses the legal and regulatory framework by indicating evolutions introduced by the French law for energy transition and for a green growth for the different renewable energies (hydroelectricity, wind energy, solar photovoltaic, geothermal, biofuels and bio-energies, biogas), by the new regimes of authorisations for onshore wind energy, methanization and hydroelectricity, and by the law for growth, activity and equality of economic opportunities. It proposes brief presentations of transverse actions (agreements, meetings, partnership in exhibitions, commitment in the COP21), and of actions regarding power grids, overseas territories, or the building sector. Some highlights related bio-energy sectors, geothermal energy, onshore wind energy, renewable marine energies and offshore wind energy, solar photovoltaic energy, hydroelectricity, or solar thermodynamic energy are mentioned. These highlights may concern legal, organisational, political or financial frameworks. Actions in the field of communication are indicated, and projects for 2016 are briefly indicated

  4. Astonishing the wild pigs highlights of technology

    CERN Document Server

    Trueb, Lucien F; Stuber, Fred A

    2015-01-01

    A hydraulic machine for astonishing wild pigs was one of the many technological highlights the author encountered in the course of his career as a research scientist and science writer. Writing a book about them, never taking more (or less) than two printed pages for each of 146 subjects was a very special challenge. The book covers fundamentally important achievements of technology that directly impacted mankind or even profoundly changed it. Many of those highlights are quite new, at least one of them (power generation by nuclear fusion) is not available yet. But particularly ingenious things dating way back were also included, as they are the base of our technical civilization Good examples are ceramics as well as copper, bronze and iron; whole periods of history have been named for the latter three. The analog computer of Antikythera used for stellar navigation was made some 2100 years ago, gunpowder was used in China as early as 1044 A.D., the astronomical clock in the Strasburg cathedral was built in th...

  5. Large eddy simulation of particulate flow inside a differentially heated cavity

    Energy Technology Data Exchange (ETDEWEB)

    Bosshard, Christoph, E-mail: christoph.bosshard@a3.epfl.ch [Paul Scherrer Institut, Laboratory for Thermalhydraulics (LTH), 5232 Villigen PSI (Switzerland); Dehbi, Abdelouahab, E-mail: abdel.dehbi@psi.ch [Paul Scherrer Institut, Laboratory for Thermalhydraulics (LTH), 5232 Villigen PSI (Switzerland); Deville, Michel, E-mail: michel.deville@epfl.ch [École Polytechnique Fédérale de Lausanne, STI-DO, Station 12, 1015 Lausanne (Switzerland); Leriche, Emmanuel, E-mail: emmanuel.leriche@univ-lille1.fr [Université de Lille I, Laboratoire de Mécanique de Lille, Avenue Paul Langevin, Cité Scientifique, F-59655 Villeneuve d’Ascq Cédex (France); Soldati, Alfredo, E-mail: soldati@uniud.it [Dipartimento di Energetica e Macchine and Centro Interdipartimentale di Fluidodinamica e Idraulica, Universitá degli Studi di Udine, Udine (Italy)

    2014-02-15

    Highlights: • Nuclear accident leads to airborne radioactive particles in containment atmosphere. • Large eddy simulation with particles in differentially heated cavity is carried out. • LES results show negligible differences with direct numerical simulation. • Four different particle sets with diameters from 10 μm to 35 μm are tracked. • Particle removal dominated by gravity settling and turbophoresis is negligible. - Abstract: In nuclear safety, some severe accident scenarios lead to the presence of fission products in aerosol form in the closed containment atmosphere. It is important to understand the particle depletion process to estimate the risk of a release of radioactivity to the environment should a containment break occur. As a model for the containment, we use the three-dimensional differentially heated cavity problem. The differentially heated cavity is a cubical box with a hot wall and a cold wall on vertical opposite sides. On the other walls of the cube we have adiabatic boundary conditions. For the velocity field the no-slip boundary condition is applied. The flow of the air in the cavity is described by the Boussinesq equations. The method used to simulate the turbulent flow is the large eddy simulation (LES) where the dynamics of the large eddies is resolved by the computational grid and the small eddies are modelled by the introduction of subgrid scale quantities using a filter function. Particle trajectories are computed using the Lagrangian particle tracking method, including the relevant forces (drag, gravity, thermophoresis). Four different sets with each set containing one million particles and diameters of 10 μm, 15 μm, 25 μm and 35 μm are simulated. Simulation results for the flow field and particle sizes from 15 μm to 35 μm are compared to previous results from direct numerical simulation (DNS). The integration time of the LES is three times longer and the smallest particles have been simulated only in the LES. Particle

  6. Eddy current NDE performance demonstrations using simulation tools

    International Nuclear Information System (INIS)

    Maurice, L.; Costan, V.; Guillot, E.; Thomas, P.

    2013-01-01

    To carry out performance demonstrations of the Eddy-Current NDE processes applied on French nuclear power plants, EDF studies the possibility of using simulation tools as an alternative to measurements on steam generator tube mocks-up. This paper focuses on the strategy led by EDF to assess and use code C armel3D and Civa, on the case of Eddy-Current NDE on wears problem which may appear in the U-shape region of steam generator tubes due to the rubbing of anti-vibration bars.

  7. Application of Eddy Currents in Medicine and their Modelling

    International Nuclear Information System (INIS)

    Krawczyk, A.; Wiak, S.; Zyss, T.; Sikora, R.

    1998-01-01

    The paper deals with the problems of interactions between the electromagnetic field and biological material, in particular the problem of eddy currents in human tissues and cells induced there for medical purposes, and the mathematical modeling of the phenomenon. The diagnostic and therapeutic effects of eddy currents are discussed and the advantages and drawbacks of these effects are given. A deeper analysis is devoted to the problem of transcranial magnetic stimulation (TMS) which is used in psychiatry as the treatment in depressive psychosis. (author)

  8. Eddy current effect in soft magnetic backlayer for PMR media

    International Nuclear Information System (INIS)

    Tanaka, T.; Yamamoto, S.; Kurisu, H.; Matsuura, M.

    2005-01-01

    Flux density distributions in the recording layer and soft magnetic backlayer of a perpendicular magnetic recording medium were calculated up to 5 GHz using a three-dimensional finite element method electromagnetic field analysis simulator, where eddy current effects in the high-frequency recording process were considered. It is presented that the flux density distribution in a recording layer hardly depends on the eddy current effect, although flux density distribution in a soft magnetic backlayer changes depending on the recording frequency and resistivity of the soft magnetic backlayer

  9. Device for ultrasonic and eddy current testing of bolts

    International Nuclear Information System (INIS)

    Hromek, J.; Kaspar, P.

    1989-01-01

    The device provides pivoting fitting of the bolt of a WWER reactor steam generator while ultrasonic and eddy current probes are brought near. The bolt under study is clamped between a drive funnel and a securing cone. The eddy current probes are adjusted using guide arms to the point requested and are fitted over the bolt such as for their thread segments to engage the bolt thread. The ultrasonic transducers are then adjusted to the required point. The device can be used for testing bolts of a thread size from M54x5 and a maximum length of 600 mm. (J.B.). 1 fig

  10. Defect detection in conducting materials using eddy current testing techniques

    Directory of Open Access Journals (Sweden)

    Brauer Hartmut

    2014-01-01

    Full Text Available Lorentz force eddy current testing (LET is a novel nondestructive testing technique which can be applied preferably to the identification of internal defects in nonmagnetic moving conductors. The LET is compared (similar testing conditions with the classical eddy current testing (ECT. Numerical FEM simulations have been performed to analyze the measurements as well as the identification of internal defects in nonmagnetic conductors. The results are compared with measurements to test the feasibility of defect identification. Finally, the use of LET measurements to estimate of the electrical conductors under test are described as well.

  11. Estimating surface fluxes using eddy covariance and numerical ogive optimization

    DEFF Research Database (Denmark)

    Sievers, J.; Papakyriakou, T.; Larsen, Søren Ejling

    2015-01-01

    Estimating representative surface fluxes using eddy covariance leads invariably to questions concerning inclusion or exclusion of low-frequency flux contributions. For studies where fluxes are linked to local physical parameters and up-scaled through numerical modelling efforts, low-frequency con......Estimating representative surface fluxes using eddy covariance leads invariably to questions concerning inclusion or exclusion of low-frequency flux contributions. For studies where fluxes are linked to local physical parameters and up-scaled through numerical modelling efforts, low...

  12. About the inclusion of eddy currents in micromagnetic computations

    International Nuclear Information System (INIS)

    Torres, L.; Martinez, E.; Lopez-Diaz, L.; Alejos, O.

    2004-01-01

    A three-dimensional dynamic micromagnetic model including the effect of eddy currents and its application to magnetization reversal processes in permalloy nanostructures is presented. Model assumptions are tangential current on the nanostructure surface, electrical neutrality and negligible displacement current. The method for solving Landau Lifschitz Gilbert equation coupled to Maxwell equations incorporating the Faraday's law is discussed in detail. The results presented for Permalloy nanocubes of 40 nm side show how the effect of eddy currents can anticipate the magnetization switching. The dependence of the calculations on computational cell size is also reported

  13. FY 1996 Congressional budget request: Budget highlights

    Energy Technology Data Exchange (ETDEWEB)

    1995-02-01

    The FY 1996 budget presentation is organized by the Department`s major business lines. An accompanying chart displays the request for new budget authority. The report compares the budget request for FY 1996 with the appropriated FY 1995 funding levels displayed on a comparable basis. The FY 1996 budget represents the first year of a five year plan in which the Department will reduce its spending by $15.8 billion in budget authority and by $14.1 billion in outlays. FY 1996 is a transition year as the Department embarks on its multiyear effort to do more with less. The Budget Highlights are presented by business line; however, the fifth business line, Economic Productivity, which is described in the Policy Overview section, cuts across multiple organizational missions, funding levels and activities and is therefore included in the discussion of the other four business lines.

  14. Highlights from NuFact05

    CERN Multimedia

    CERN. Geneva; Landua, Rolf

    2005-01-01

    The 7th International Workshop on Neutrino Factories and Superbeams was held in Frascati in June 2005 with nearly 200 participants. The most recent progress in the design of future neutrino facilities was described, including novel ideas in detectors, and many issues were raised. The International Scoping Study (ISS) for a future Neutrino Facility which would incorporate a Neutrino Factory and/or a high intensity Neutrino Superbeam was launched at that occasion. Built upon previous studies in the USA, Europe and Japan, it will aim to i) define the physics case and a baseline design for such a facility including the related neutrino detection systems, ii) identify the required research and development programme and iii) perform comparisons with other options such as beta beams. The highlights of the meeting and the upcoming studies will be presented.

  15. Research highlights: impacts of microplastics on plankton.

    Science.gov (United States)

    Lin, Vivian S

    2016-02-01

    Each year, millions of metric tons of the plastic produced for food packaging, personal care products, fishing gear, and other human activities end up in lakes, rivers, and the ocean. The breakdown of these primary plastics in the environment results in microplastics, small fragments of plastic typically less than 1-5 mm in size. These synthetic particles have been detected in all of the world's oceans and also in many freshwater systems, accumulating in sediment, on shorelines, suspended in surface waters, and being ingested by plankton, fish, birds, and marine mammals. While the occurrence of plastics in surface waters has been surveyed in a number of studies, the impacts of microplastics on marine organisms are still being elucidated. This highlight features three recent publications that explore the interactions of microplastics with planktonic organisms to clarify the effects of these pollutants on some of the ocean's smallest and most important inhabitants.

  16. LHC INAUGURATION, LHC Fest highlights: exhibition time!

    CERN Multimedia

    2008-01-01

    David Gross, one of the twenty-one Nobel Laureates who have participated in the project.Tuesday 21 October 2008 Accelerating Nobels Colliding Charm, Atomic Cuisine, The Good Anomaly, A Quark Somewhere on the White Paper, Wire Proliferation, A Tale of Two Liquids … these are just some of the titles given to artworks by Physics Nobel Laureates who agreed to make drawings of their prize-winning discoveries (more or less reluctantly) during a special photo session. Science photographer Volker Steger made portraits of Physics Nobel Laureates and before the photo sessions he asked them to make a drawing of their most important discovery. The result is "Accelerating Nobels", an exhibition that combines unusual portraits of and original drawings by twenty-one Nobel laureates in physics whose work is closely related to CERN and the LHC. This exhibition will be one of the highlights of the LHC celebrations on 21 October in the SM18 hall b...

  17. Transport Task Force workshop: basic experiments highlights

    Energy Technology Data Exchange (ETDEWEB)

    Linford, R.K. (Los Alamos National Lab., NM (USA)); Luckhardt, S. (Massachusetts Inst. of Tech., Cambridge, MA (USA)); Lyon, J.F. (Oak Ridge National Lab., TN (USA)); Navratil, G.A. (Columbia Univ., New York, NY (USA)); Schoenberg, K.F. (Los Alamos National Lab., NM (USA))

    1990-01-01

    Selected topics are summarized from the Basic Experiments session of the Transport Task Force Workshop held August 21-24, 1989, in San Diego, California. This session included presentations on paradigm experiments, stellarators, reversed-field pinches, and advanced tokamaks. Recent advances in all of these areas illustrate the importance of these experiments in advancing our understanding of toroidal transport. Progress has been made in measuring the details of particle diffusion, isolating specific modes, measuring fluctuation variations with field geometry and beta, and comparing all these with theoretical predictions. The development of experimental tools for determining which fluctuations dominate transport are also reported. Continued significant advances are anticipated in a number of areas highlighted. (author).

  18. Transport Task Force workshop: basic experiments highlights

    International Nuclear Information System (INIS)

    Linford, R.K.; Luckhardt, S.; Lyon, J.F.; Navratil, G.A.; Schoenberg, K.F.

    1990-01-01

    Selected topics are summarized from the Basic Experiments session of the Transport Task Force Workshop held August 21-24, 1989, in San Diego, California. This session included presentations on paradigm experiments, stellarators, reversed-field pinches, and advanced tokamaks. Recent advances in all of these areas illustrate the importance of these experiments in advancing our understanding of toroidal transport. Progress has been made in measuring the details of particle diffusion, isolating specific modes, measuring fluctuation variations with field geometry and beta, and comparing all these with theoretical predictions. The development of experimental tools for determining which fluctuations dominate transport are also reported. Continued significant advances are anticipated in a number of areas highlighted. (author)

  19. Symmetric configurations highlighted by collective quantum coherence

    Energy Technology Data Exchange (ETDEWEB)

    Obster, Dennis [Radboud University, Institute for Mathematics, Astrophysics and Particle Physics, Nijmegen (Netherlands); Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan); Sasakura, Naoki [Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan)

    2017-11-15

    Recent developments in quantum gravity have shown the Lorentzian treatment to be a fruitful approach towards the emergence of macroscopic space-times. In this paper, we discuss another related aspect of the Lorentzian treatment: we argue that collective quantum coherence may provide a simple mechanism for highlighting symmetric configurations over generic non-symmetric ones. After presenting the general framework of the mechanism, we show the phenomenon in some concrete simple examples in the randomly connected tensor network, which is tightly related to a certain model of quantum gravity, i.e., the canonical tensor model. We find large peaks at configurations invariant under Lie-group symmetries as well as a preference for charge quantization, even in the Abelian case. In future study, this simple mechanism may provide a way to analyze the emergence of macroscopic space-times with global symmetries as well as various other symmetries existing in nature, which are usually postulated. (orig.)

  20. Physical Sciences 2007 Science & Technology Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Hazi, A U

    2008-04-07

    The Physical Sciences Directorate applies frontier physics and technology to grand challenges in national security. Our highly integrated and multidisciplinary research program involves collaborations throughout Lawrence Livermore National Laboratory, the National Nuclear Security Administration, the Department of Energy, and with academic and industrial partners. The Directorate has a budget of approximately $150 million, and a staff of approximately 350 employees. Our scientists provide expertise in condensed matter and high-pressure physics, plasma physics, high-energy-density science, fusion energy science and technology, nuclear and particle physics, accelerator physics, radiation detection, optical science, biotechnology, and astrophysics. This document highlights the outstanding research and development activities in the Physical Sciences Directorate that made news in 2007. It also summarizes the awards and recognition received by members of the Directorate in 2007.

  1. Highlights from the 9th Cachexia Conference.

    Science.gov (United States)

    Ebner, Nicole; von Haehling, Stephan

    2017-06-01

    This article highlights updates of pathways as well as pre-clinical and clinical studies into the field of wasting disorders that were presented at the 9th Cachexia Conference held in Berlin, Germany, December 2016. This year, some interesting results from clinical trials and different new therapeutic targets were shown. This article presents the biological and clinical significance of different markers and new diagnostic tools and cut-offs of detecting skeletal muscle wasting. Effective treatments of cachexia and wasting disorders are urgently needed in order to improve the patients' quality of life and their survival. © 2017 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.

  2. Syndicate of renewable energies - Highlights 2016

    International Nuclear Information System (INIS)

    2017-01-01

    This publication first proposes a presentation of the SER (Syndicat des Energies Renouvelables, Syndicate of Renewable Energies), a professional body: missions, scope of action, members. It outlines its commitment in the French policy for energy transition as a major actor of the sector of renewable energies. It addresses the legal and regulatory framework as well as the economic framework and markets. It proposes brief presentations of transverse actions regarding power grids, overseas territories, the building sector and the international export. Some highlights related to ground-based wind power, renewable marine energies and offshore wind energy, solar photovoltaic energy, bio-energies (wood-fueled power plants for collective, tertiary and industrial sectors, biogas, biofuels and municipal wastes), domestic wood space heating, geothermal energy and hydroelectricity are mentioned. Actions in the field of communication are summarized, and projects for 2017 are briefly indicated

  3. ATOMLLL: atoms with shading and highlights

    International Nuclear Information System (INIS)

    Max, N.L.; y.

    1979-01-01

    The ATOMS program, written at Bell Telephone Laboratory, is capable of determining the visible portions of a scene consisting of interpenetrating spheres and cylinders, put together to represent space-filling or ball-and-stick molecular models. The Lawrence Livermore Laboratory version contains enhancements to add shading and highlights, and to render the spheres on film as ellipses, so they will appear round when projected in various wide-screen formats. The visible parts of each sphere or cylinder are shaded by a minicomputer controlling the film recorder, thus releasing the main computer from transferring the millions of intensity values for each frame. The minicomputer is microprogrammed with an efficient algorithm for the intensities, which uses the color look-up tables in the film recorder to store the reflectance as a function of angle of incidence. 8 references

  4. Research highlights: microfluidics meets big data.

    Science.gov (United States)

    Tseng, Peter; Weaver, Westbrook M; Masaeli, Mahdokht; Owsley, Keegan; Di Carlo, Dino

    2014-03-07

    In this issue we highlight a collection of recent work in which microfluidic parallelization and automation have been employed to address the increasing need for large amounts of quantitative data concerning cellular function--from correlating microRNA levels to protein expression, increasing the throughput and reducing the noise when studying protein dynamics in single-cells, and understanding how signal dynamics encodes information. The painstaking dissection of cellular pathways one protein at a time appears to be coming to an end, leading to more rapid discoveries which will inevitably translate to better cellular control--in producing useful gene products and treating disease at the individual cell level. From these studies it is also clear that development of large scale mutant or fusion libraries, automation of microscopy, image analysis, and data extraction will be key components as microfluidics contributes its strengths to aid systems biology moving forward.

  5. AGILE Data Center and AGILE science highlights

    International Nuclear Information System (INIS)

    Pittori, C.

    2013-01-01

    AGILE is a scientific mission of the Italian Space Agency (ASI) with INFN, INAF e CIFS participation, devoted to gamma-ray astrophysics. The satellite is in orbit since April 23rd, 2007. Gamma-ray astrophysics above 100 MeV is an exciting field of astronomical sciences that has received a strong impulse in recent years. Despite the small size and budget, AGILE produced several important scientific results, among which the unexpected discovery of strong and rapid gamma-ray flares from the Crab Nebula. This discovery won to the AGILE PI and the AGILE Team the prestigious Bruno Rossi Prize for 2012, an international recognition in the field of high energy astrophysics. We present here the AGILE data center main activities, and we give an overview of the AGILE scientific highlights after 5 years of operations

  6. 2006 highlights according to the IEA

    International Nuclear Information System (INIS)

    Lafon, M.

    2007-01-01

    The 2007 natural gas market review of the International energy agency (IEA) is this year subtitled: 'security in a globalizing market to 2015'. The review thus stresses on the 2006 highlights but reinforces the idea already expressed in the 2006 issue that energy security is now an inevitable topic. It offers also a prospective analysis of the natural gas market up to 2015 and devotes a full chapter to LNG development. As a matter of fact, the IEA considers that, from now to 2015, two thirds of the additional gas supplies will be in the form of LNG. The review supplies also some complements about some national markets. The present article reviews the most important points of this analysis. (J.S.)

  7. Physical Sciences 2007 Science and Technology Highlights

    International Nuclear Information System (INIS)

    Hazi, A.U.

    2008-01-01

    The Physical Sciences Directorate applies frontier physics and technology to grand challenges in national security. Our highly integrated and multidisciplinary research program involves collaborations throughout Lawrence Livermore National Laboratory, the National Nuclear Security Administration, the Department of Energy, and with academic and industrial partners. The Directorate has a budget of approximately $150 million, and a staff of approximately 350 employees. Our scientists provide expertise in condensed matter and high-pressure physics, plasma physics, high-energy-density science, fusion energy science and technology, nuclear and particle physics, accelerator physics, radiation detection, optical science, biotechnology, and astrophysics. This document highlights the outstanding research and development activities in the Physical Sciences Directorate that made news in 2007. It also summarizes the awards and recognition received by members of the Directorate in 2007

  8. Brookhaven highlights, October 1978-September 1979

    International Nuclear Information System (INIS)

    1979-01-01

    These highlights present an overview of the major research and development achievements at Brookhaven National Laboratory from October 1978 to September 1979. Specific areas covered include: accelerator and high energy physics programs; high energy physics research; the AGS and improvements to the AGS; neutral beam development; heavy ion fusion; superconducting power cables; ISABELLE storage rings; the BNL Tandem accelerator; heavy ion experiments at the Tandem; the High Flux Beam Reactor; medium energy physics; nuclear theory; atomic and applied physics; solid state physics; neutron scattering studies; x-ray scattering studies; solid state theory; defects and disorder in solids; surface physics; the National Synchrotron Light Source ; Chemistry Department; Biology Department; Medical Department; energy sciences; environmental sciences; energy technology programs; National Center for Analysis of Energy Systems; advanced reactor systems; nuclear safety; National Nuclear Data Center; nuclear materials safeguards; Applied Mathematics Department; and support activities

  9. Time evolution of the eddy viscosity in two-dimensional navier-stokes flow

    Science.gov (United States)

    Chaves; Gama

    2000-02-01

    The time evolution of the eddy viscosity associated with an unforced two-dimensional incompressible Navier-Stokes flow is analyzed by direct numerical simulation. The initial condition is such that the eddy viscosity is isotropic and negative. It is shown by concrete examples that the Navier-Stokes dynamics stabilizes negative eddy viscosity effects. In other words, this dynamics moves monotonically the initial negative eddy viscosity to positive values before relaxation due to viscous term occurs.

  10. Biotransformation and bioactivation reactions - 2016 literature highlights.

    Science.gov (United States)

    Khojasteh, S Cyrus; Rietjens, Ivonne M C M; Dalvie, Deepak; Miller, Grover

    2017-08-01

    We are pleased to present a second annual issue highlighting a previous year's literature on biotransformation and bioactivation. Each contributor to this issue worked independently to review the articles published in 2016 and proposed three to four articles, which he or she believed would be of interest to the broader research community. In each synopsis, the contributing author summarized the procedures, analyses and conclusions as described in the original manuscripts. In the commentary sections, our authors offer feedback and highlight aspects of the work that may not be apparent from an initial reading of the article. To be fair, one should still read the original article to gain a more complete understanding of the work conducted. Most of the articles included in this review were published in Drug Metabolism and Disposition or Chemical Research in Toxicology, but attempts were made to seek articles in 25 other journals. Importantly, these articles are not intended to represent a consensus of the best papers of the year, as we did not want to make any arbitrary standards for this purpose, but rather they were chosen by each author for their notable findings and descriptions of novel metabolic pathways or biotransformations. I am pleased that Drs. Rietjens and Dalvie have again contributed to this annual review. We would like to welcome Grover P Miller as an author for this year's issue, and we thank Tom Baillie for his contributions to last year's edition. We have intentionally maintained a balance of authors such that two come from an academic setting and two come from industry. Finally, please drop us a note if you find this review helpful. We would be pleased to hear your opinions of our commentary, and we extend an invitation to anyone who would like to contribute to a future edition of this review. This article is dedicated to Professor Thomas Baillie for his exceptional contributions to the field of drug metabolism.

  11. Dynamics and role of the Durban cyclonic eddy in the KwaZulu ...

    African Journals Online (AJOL)

    Analysis of ADCP data and satellite imagery shows the eddy to be present off Durban approximately 55% of the time, with an average lifespan of 8.6 days, and inter-eddy periods of 4 to 8 days. After spin-up the eddy breaks loose from its lee position and propagates downstream on the inshore boundary of the Agulhas ...

  12. The link between eddy-driven jet variability and weather regimes in the North Atlantic-European sector

    Science.gov (United States)

    Madonna, E.; Li, C.; Grams, C. M.; Woollings, T.

    2017-12-01

    Understanding the variability of the North Atlantic eddy-driven jet is key to unravelling the dynamics, predictability and climate change response of extratropical weather in the region. This study aims to 1) reconcile two perspectives on wintertime variability in the North Atlantic-European sector and 2) clarify their link to atmospheric blocking. Two common views of wintertime variability in the North Atlantic are the zonal-mean framework comprising three preferred locations of the eddy-driven jet (southern, central, northern), and the weather regime framework comprising four classical North Atlantic-European regimes (Atlantic ridge AR, zonal ZO, European/Scandinavian blocking BL, Greenland anticyclone GA). We use a k-means clustering algorithm to characterize the two-dimensional variability of the eddy-driven jet stream, defined by the lower tropospheric zonal wind in the ERA-Interim reanalysis. The first three clusters capture the central jet and northern jet, along with a new mixed jet configuration; a fourth cluster is needed to recover the southern jet. The mixed cluster represents a split or strongly tilted jet, neither of which is well described in the zonal-mean framework, and has a persistence of about one week, similar to the other clusters. Connections between the preferred jet locations and weather regimes are corroborated - southern to GA, central to ZO, and northern to AR. In addition, the new mixed cluster is found to be linked to European/Scandinavian blocking, whose relation to the eddy-driven jet was previously unclear. The results highlight the necessity of bridging from weather to climate scales for a deeper understanding of atmospheric circulation variability.

  13. Ten questions concerning the large-eddy simulation of turbulent flows

    International Nuclear Information System (INIS)

    Pope, Stephen B

    2004-01-01

    In the past 30 years, there has been considerable progress in the development of large-eddy simulation (LES) for turbulent flows, which has been greatly facilitated by the substantial increase in computer power. In this paper, we raise some fundamental questions concerning the conceptual foundations of LES and about the methodologies and protocols used in its application. The 10 questions addressed are stated at the end of the introduction. Several of these questions highlight the importance of recognizing the dependence of LES calculations on the artificial parameter Δ (i.e. the filter width or, more generally, the turbulence resolution length scale). The principle that LES predictions of turbulence statistics should depend minimally on Δ provides an alternative justification for the dynamic procedure

  14. Modelling and simulation of eddy current non-destructive testing

    International Nuclear Information System (INIS)

    Mansir, H.; Burais, N.; Nicolas, A.

    1986-01-01

    This paper presents the practical configuration for detecting cracks in conducting materials by eddy current non destructive testing. An electromagnetic field formulation is proposed using Maxwell's relations. Geometrical and physical properties of the crack are taken into account by several models, particularly with a new finite element called ''crack element''. Modelisation is applied to sensor impedance calculation with classical numerical methods [fr

  15. Eddy Covariance Measurements of the Sea-Spray Aerosol Flu

    Science.gov (United States)

    Brooks, I. M.; Norris, S. J.; Yelland, M. J.; Pascal, R. W.; Prytherch, J.

    2015-12-01

    Historically, almost all estimates of the sea-spray aerosol source flux have been inferred through various indirect methods. Direct estimates via eddy covariance have been attempted by only a handful of studies, most of which measured only the total number flux, or achieved rather coarse size segregation. Applying eddy covariance to the measurement of sea-spray fluxes is challenging: most instrumentation must be located in a laboratory space requiring long sample lines to an inlet collocated with a sonic anemometer; however, larger particles are easily lost to the walls of the sample line. Marine particle concentrations are generally low, requiring a high sample volume to achieve adequate statistics. The highly hygroscopic nature of sea salt means particles change size rapidly with fluctuations in relative humidity; this introduces an apparent bias in flux measurements if particles are sized at ambient humidity. The Compact Lightweight Aerosol Spectrometer Probe (CLASP) was developed specifically to make high rate measurements of aerosol size distributions for use in eddy covariance measurements, and the instrument and data processing and analysis techniques have been refined over the course of several projects. Here we will review some of the issues and limitations related to making eddy covariance measurements of the sea spray source flux over the open ocean, summarise some key results from the last decade, and present new results from a 3-year long ship-based measurement campaign as part of the WAGES project. Finally we will consider requirements for future progress.

  16. Apparatus For Eddy-Current Inspection Of Bolts

    Science.gov (United States)

    Amos, Jay M.

    1994-01-01

    Eddy-current apparatus for inspection of bolts, studs, and other threaded fasteners detects flaws in threads, shanks, and head fillets. With help of apparatus, technician quickly inspects fasteners of various dimensions. Accommodates fasteners with diameters from 0.190 in. to 1 in. and with lengths up to 5 in. Basic design modified to accommodate fasteners of other sizes.

  17. A subsurface cyclonic eddy in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Babu, M.T.; PrasannaKumar, S.; Rao, D.P.

    and to a larger extent from the action of wind stress curl while in the southern part the northward current is purely wind-driven. High stratification causEd. by fresh water influx prevented the eddy from being detected at the surface....

  18. Large Eddy Simulation of Sydney Swirl Non-Reaction Jets

    DEFF Research Database (Denmark)

    Yang, Yang; Kær, Søren Knudsen; Yin, Chungen

    The Sydney swirl burner non-reaction case was studied using large eddy simulation. The two-point correlation method was introduced and used to estimate grid resolution. Energy spectra and instantaneous pressure and velocity plots were used to identify features in flow field. By using these method......, vortex breakdown and precessing vortex core are identified and different flow zones are shown....

  19. Eddy current technique applied to automated tube profilometry

    International Nuclear Information System (INIS)

    Dobbeni, D.; Melsen, C. van

    1982-01-01

    The use of eddy current methods in the first totally automated pre-service inspection of the internal diameter of PWR steam generator tubes is described. The technique was developed at Laborelec, the Belgian Laboratory of the Electricity Supply Industry. Details are given of the data acquisition system and of the automated manipulator. Representative tube profiles are illustrated. (U.K.)

  20. A Laboratory Activity on the Eddy Current Brake

    Science.gov (United States)

    Molina-Bolivar, J. A.; Abella-Palacios, A. J.

    2012-01-01

    The aim of this paper is to introduce a simple and low-cost experimental setup that can be used to study the eddy current brake, which considers the motion of a sliding magnet on an inclined conducting plane in terms of basic physical principles. We present a set of quantitative experiments performed to study the influence of the geometrical and…

  1. Studies of microstructured falling film reactor using Eddy diffusivity concepts

    NARCIS (Netherlands)

    Cantu-Perez, A.; Al-Rawashdeh, M.I.M.; Hessel, V.; Gavriilidis, A.

    2012-01-01

    Introduction. This work introduces a model for the absorption of CO2 in a falling film microreactor that incorporates staggered herringbone structures. The effect of the herringbone structures was incorporated into the model via a position dependent eddy diffusivity obtained from turbulent theory

  2. Principles and applications of multiplane pulsed eddy currents

    International Nuclear Information System (INIS)

    David, B.; Champonnois, F.; Joffre, F.

    1989-01-01

    A pulsed device using eddy currents, producing 8 shape signals on the screen like a sine wave system, has been developed. The method has been applied to the well-known problem of defects in stainless claddings of PWR reactor vessels

  3. Eddie Murphy grimmile kulus üheksa kuud / Triin Tael

    Index Scriptorium Estoniae

    Tael, Triin

    2007-01-01

    Uues USA komöödiafilmis "Norbit" (režissöör Brian Robbins, stsenarist näitleja vend Charles Murphy) mängib Eddie Murphy kolme täiesti erinevat rolli. Seejuures aitas teda grimmikunstnik Rick Baker

  4. Integral Model of Eddy Currents in Nonmagnetic Structures

    Czech Academy of Sciences Publication Activity Database

    Doležel, Ivo; Karban, P.

    2004-01-01

    Roč. 4, č. 3 (2004), s. 5-12 ISSN 1335-8243 R&D Projects: GA ČR GA102/03/0047 Keywords : magnetic field * eddy currents * integral equations Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  5. Subminiature eddy current transducers for studying boride coatings

    Science.gov (United States)

    Dmitriev, S. F.; Ishkov, A. V.; Malikov, V. N.; Sagalakov, A. M.

    2016-07-01

    Strengthening of parts and units of machines, increased reliability and longer service life is an important task of modern mechanical engineering. The main objects of study in the work were selected steel 65G and 50HGA, wear-resistant boride coatings ternary system Fe-B-Fe n B which were investigated by scanning electron microscopy and eddy-current nondestructive methods.

  6. Large-eddy simulation of highly underexpanded transient gas jets

    NARCIS (Netherlands)

    Vuorinen, V.; Yu, J.; Tirunagari, S.; Kaario, O.; Larmi, M.; Duwig, C.; Boersma, B.J.

    2013-01-01

    Large-eddy simulations (LES) based on scale-selective implicit filtering are carried out in order to study the effect of nozzle pressure ratios on the characteristics of highly underexpanded jets. Pressure ratios ranging from 4.5 to 8.5 with Reynolds numbers of the order 75?000–140?000 are

  7. Large eddy simulations of an airfoil in turbulent inflow

    DEFF Research Database (Denmark)

    Gilling, Lasse; Sørensen, Niels N.

    2008-01-01

    Wind turbines operate in the turbulent boundary layer of the atmosphere and due to the rotational sampling effect the blades experience a high level of turbulence [1]. In this project the effect of turbulence is investigated by large eddy simulations of the turbulent flow past a NACA 0015 airfoil...

  8. AGILE Highlights after Six Years in Orbit

    Directory of Open Access Journals (Sweden)

    Carlotta Pittori

    2014-12-01

    Full Text Available AGILE is an ASI space mission in collaboration with INAF, INFN and CIFS, dedicated to the observation of the gamma-ray Universe in the 30 MeV - 50 GeV energy range, with simultaneous X-ray imaging capability in the 18-60 keV band. The AGILE satellite was launched on April 23rd, 2007, and produced several important scientic results, among which the unexpected discovery of strong ares from the Crab Nebula. This discovery won to the AGILE PI and the AGILE Team the Bruno Rossi Prize for 2012 by the High Energy Astrophysics division of the American Astronomical Society. Thanks to its sky monitoring capability and fast ground segment alert system, AGILE detected many Galactic and extragalactic sources: among other results AGILE discovered gamma-ray emission from the microquasar Cygnus X-3, detected many bright blazars, discovered several new gamma-ray pulsars, and discovered emission up to 100 MeV from Terrestrial Gamma-Ray Flashes. We present an overview of the main AGILE Data Center activities and the AGILE scientic highlights after 6 years of operations.

  9. LHC Highlights, from dream to reality

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    The idea of the Large Hadron Collider (LHC) was born in the early 1980s. Although LEP (CERN’s previous large accelerator) was still under construction at that time, scientists were already starting to think about re-using the 27-kilometre ring for an even more powerful machine. Turning this ambitious scientific plan into reality proved to be an immensely complex task. Civil engineering work, state-of-the-art technologies, a new approach to data storage and analysis: many people worked hard for many years to accomplish all this.   Here are some of the highlights: 1984. A symposium organized in Lausanne, Switzerland, is the official starting point for the LHC. LHC prototype of the two beam pipes (1992). 1989. The first embryonic collaborations begin. 1992. A meeting in Evian, France, marks the beginning of the LHC experiments. 1994. The CERN Council approves the construction of the LHC accelerator. 1995. Japan becomes an Observer of CERN and announces a financial contribution to ...

  10. Argonne National Laboratory Research Highlights 1988

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    The research and development highlights are summarized. The world's brightest source of X-rays could revolutionize materials research. Test of a prototype insertion device, a key in achieving brilliant X-ray beams, have given the first glimpse of the machine's power. Superconductivity research focuses on the new materials' structure, economics and applications. Other physical science programs advance knowledge of material structures and properties, nuclear physics, molecular structure, and the chemistry and structure of coal. New programming approaches make advanced computers more useful. Innovative approaches to fighting cancer are being developed. More experiments confirm the passive safety of Argonne's Integral Fast Reactor concept. Device simplifies nuclear-waste processing. Advanced fuel cell could provide better mileage, more power than internal combustion engine. New instruments find leaks in underground pipe, measure sodium impurities in molten liquids, detect flaws in ceramics. New antibody findings may explain ability to fight many diseases. Cadmium in cigarettes linked to bone loss in women. Programs fight deforestation in Nepal. New technology could reduce acid rain, mitigate greenhouse effect, enhance oil recovery. Innovative approaches transfer Argonne-developed technology to private industry. Each year Argonne educational programs reach some 1200 students

  11. Highlights from past and future physics

    CERN Multimedia

    Daisy Yuhas

    2009-01-01

    A two-day symposium was held at CERN on 3 and 4 December in celebration of the fiftieth anniversary of the Proton Synchrotron and the twentieth anniversary of LEP. The symposium, entitled “From the Proton Synchrotron to the Large Hadron Collider- 50 Years of Nobel Memories in High-Energy Physics”, included a series of seminars reflecting on the past fifty years in particle physics and an exhibition highlighting CERN’s research over this period.   Lyn Evans, LHC project leader, addressing the audience gathered in the Main Auditorium during the symposium that celebrated the 50 years of the PS and the 20 years of LEP.  The events were well attended on both days. Thursday’s reception, to which the Director-General invited everyone working at CERN, attracted over 1200 people. The seminars drew about 500 people to the Main Auditorium and the Council Chamber each day, with at least as many on-line attendees. The symposium speakers, including thirteen No...

  12. Highlights on the IAEA project QUATRO

    International Nuclear Information System (INIS)

    Milano, F.

    2012-01-01

    The success of radiotherapy in term of prob- ability of local control of the tumor and the limiting factor in treatments in term of probability of complications are strictly depending on the accuracy and precision of the pa- tient treatment. An overall Quality Assurance programme (QAP) has been recognized as an essential tool to assure that the goals of radiotherapy are achieved. As part of a comprehensive approach to QAP an independent external audit is considered a very effective method of checking that the quality of activities in an Institution permits to achieve the required objectives. Since many years the International Atomic Energy Agency (IAEA) has audited Member States for radiotherapy dosimetry, for educating and training radio- therapy professionals and for reviewing the radiotherapy process. Recently a new approach has been developed and named ''Quality Assurance Team for Radiation Oncology (QUATRO)''. The principal aim of QUATRO is to review all the radiotherapy process, including organization, infra- structure, clinical and medical physics aspects of the radio- therapy services. It also includes a review of the hospital's professional competence with a view to quality improve- ment. The aim of this paper is to introduce and to highlight the QUATRO methodology describing its effectiveness on improving either the quality of the radiotherapy treatments and in general the management of the patient.

  13. Engineering sciences research highlights. Fiscal year 1983

    International Nuclear Information System (INIS)

    Tucker, E.F.; Dobratz, B.

    1984-05-01

    The Laboratory's overall mission is sixfold. We are charged with developing nuclear warheads for defense, technology for arms control, and new concepts for defense against nuclear attack; with supporting programs for both nonnuclear defense and energy research and development; and with advancing our knowledge of science and technology so that we can respond to other national needs. Major programs in support of this mission involve nuclear weapons, energy, environmental science, and basic research. Specific areas of investigation include the design, development, and testing of nuclear weapons; nuclear safeguards and security; inertial and magnetic fusion and nuclear, solar, fossil, and geothermal energy; and basic research in physics, chemistry, mathematics, engineering, and the computer and life sciences. With the staff and facilities maintained for these and other programs, the Laboratory can respond to specific national needs in virtually all areas of the physical and life sciences. Within the Laboratory's organization, most technical research activities are carried out in three directorates: Engineering Sciences; Physics and Mathematics; and Chemistry, Earth and Life Sciences. The activities highlighted here are examples of unclassified work carried out in the seven divisions that made up the Engineering Sciences Directorate at the end of fiscal year 1983. Brief descriptions of these divisions' goals and capabilities and summaries of selected projects illustrate the diversity of talent, expertise, and facilities maintained within the Engineering Sciences Directorate

  14. Cyclonic eddies identified in the Cape Basin of the South Atlantic Ocean

    Science.gov (United States)

    Hall, C.; Lutjeharms, J. R. E.

    2011-03-01

    Inter-ocean exchange south of Africa takes place largely through the movement of Agulhas Rings into the Cape Basin. Recent observations have shown that the highly energetic flow field in this basin consists of anti-cyclonic rings as well as cyclonic eddies. Very little is known of the characteristics of the cyclonic eddies. Using altimetric data, this study determines the location, frequency and seasonality of these cyclonic eddies their size, trajectories, life spans and their association with Agulhas Rings. Cyclonic eddies were seen to split, merge and link with other cyclonic eddies, where splitting events created child cyclonic eddies. The 105 parent and 157 child cyclonic eddies identified over a decade show that on average 11 parent and 17 child cyclonic eddies appear annually in AVISO merged absolute dynamic topography data along the continental slope. Thirty-two percent follow an overall west south-westward direction, with 27% going west north-westward. Average translocation speeds are 2.2 ± 0.1 km/day for parent and 3.0 ± 0.2 km/day for child cyclonic eddies. Parent cyclonic eddy lifespan averaged 250 ± 18 days; whereas child cyclonic eddies survived for only 118 ± 11 days. A significant difference in lifespan for parent and child cyclonic eddies identified in the north and south region of the study area was detected. Seventy-seven percent of the northern and 93% of the southern cyclonic eddies were first detected directly adjacent to passing Agulhas Rings, suggesting a vital interaction between these mesoscale eddies within the region. Topographical features appeared to affect the behaviour and lifespan of these deep cyclonic eddies.

  15. Theoretical and practical program in the non-destructive testing by eddy currents - the first level

    International Nuclear Information System (INIS)

    Shaaban, H.I.; Addarwish, J.M.A.

    2014-11-01

    The testing using eddy currents is one of the non-destructive tests that use electromagnetic property as a basis for testing procedures, and there are many other ways to use this principle, including Remote Field Testing and the Magnetic Flux Leakage test. Eddy currents are electrical currents moving in a circular path, and took the name eddy of eddies that form when a liquid or gas is moving in a circular path because of objection obstacles to its track. They are generated in the material using a variable magnetic field. Non-destructive testing by eddy currents is a technique used for the detection of defects and interruptions in a material and it is a process that relies on the generation of small eddy currents in the material of the part to be examined, provided that this part is of an electrically conducting material. This technique and its scientific basis are explained in this book. Also the devices used in this technique and how to use these devices in details are explained. The book contains Twelve chapters: Introduction to non destructive testing - Engineering materials and its mechanical characteristics - Electrical and magnetic characteristics of engineering materials - Introduction to testing by eddy currents - Factors affecting eddy currents - Basis of electrical circuits used in eddy currents testing devices - Probes of eddy currents testing - Eddy currents testing devices (Theoretical) - Analysis of the examination results of testing by eddy currents: techniques and applications - Applications of testing by eddy currents - Eddy currents testing devices (Application) - Practical lessons for the first level in testing by eddy currents.

  16. GEM: a dynamic tracking model for mesoscale eddies in the ocean

    Science.gov (United States)

    Li, Qiu-Yang; Sun, Liang; Lin, Sheng-Fu

    2016-12-01

    The Genealogical Evolution Model (GEM) presented here is an efficient logical model used to track dynamic evolution of mesoscale eddies in the ocean. It can distinguish between different dynamic processes (e.g., merging and splitting) within a dynamic evolution pattern, which is difficult to accomplish using other tracking methods. To this end, the GEM first uses a two-dimensional (2-D) similarity vector (i.e., a pair of ratios of overlap area between two eddies to the area of each eddy) rather than a scalar to measure the similarity between eddies, which effectively solves the "missing eddy" problem (temporarily lost eddy in tracking). Second, for tracking when an eddy splits, the GEM uses both "parent" (the original eddy) and "child" (eddy split from parent) and the dynamic processes are described as the birth and death of different generations. Additionally, a new look-ahead approach with selection rules effectively simplifies computation and recording. All of the computational steps are linear and do not include iteration. Given the pixel number of the target region L, the maximum number of eddies M, the number N of look-ahead time steps, and the total number of time steps T, the total computer time is O(LM(N + 1)T). The tracking of each eddy is very smooth because we require that the snapshots of each eddy on adjacent days overlap one another. Although eddy splitting or merging is ubiquitous in the ocean, they have different geographic distributions in the North Pacific Ocean. Both the merging and splitting rates of the eddies are high, especially at the western boundary, in currents and in "eddy deserts". The GEM is useful not only for satellite-based observational data, but also for numerical simulation outputs. It is potentially useful for studying dynamic processes in other related fields, e.g., the dynamics of cyclones in meteorology.

  17. Near-surface eddy dynamics in the Southern Ocean

    Directory of Open Access Journals (Sweden)

    Marilisa Trani

    2011-12-01

    Full Text Available The Antarctic Circumpolar Current (ACC is a crucial component of the global ocean conveyor belt, acting as a zonal link among the major ocean basins but, to some extent, limiting meridional exchange and tending to isolate the ocean south of it from momentum and heat income. In this work we investigate one of the most important mechanisms contributing to the poleward transfer of properties in the Southern Ocean, that is the eddy component of the dynamics. For this particular purpose, observations obtained from near-surface drifters have been used: they represent a very useful data set to analyse the eddy field because of their ability to catch a large number of scales of motion while providing a quasi-synoptic coverage of the investigated area. Estimates of the eddy heat and momentum fluxes are carried out using data taken from the Global Drifter Program databank; they refer to Surface Velocity Program drifter trajectories collected in the area south of 35°S between 1995 and 2006. Eddy kinetic energies, variance ellipses, momentum and heat fluxes have been calculated using the pseudo-Eulerian method, showing patterns in good agreement with those present in the literature based on observational and model data, although there are some quantitative differences. The eddy fluxes have been separated into their rotational and divergent portions, the latter being responsible for the meridional transports. The associated zonal and depth-exponentially integrated meridional heat transport exhibits values spanning over a range between -0.4 PW and –1.1 PW in the ACC region, consistent with previous estimates.

  18. Influence of magnet eddy current on magnetization characteristics of variable flux memory machine

    Science.gov (United States)

    Yang, Hui; Lin, Heyun; Zhu, Z. Q.; Lyu, Shukang

    2018-05-01

    In this paper, the magnet eddy current characteristics of a newly developed variable flux memory machine (VFMM) is investigated. Firstly, the machine structure, non-linear hysteresis characteristics and eddy current modeling of low coercive force magnet are described, respectively. Besides, the PM eddy current behaviors when applying the demagnetizing current pulses are unveiled and investigated. The mismatch of the required demagnetization currents between the cases with or without considering the magnet eddy current is identified. In addition, the influences of the magnet eddy current on the demagnetization effect of VFMM are analyzed. Finally, a prototype is manufactured and tested to verify the theoretical analyses.

  19. Sea Surface Height Variability and Eddy Statistical Properties in the Red Sea

    KAUST Repository

    Zhan, Peng

    2013-05-01

    Satellite sea surface height (SSH) data over 1992-2012 are analyzed to study the spatial and temporal variability of sea level in the Red Sea. Empirical orthogonal functions (EOF) analysis suggests the remarkable seasonality of SSH in the Red Sea, and a significant correlation is found between SSH variation and seasonal wind cycle. A winding-angle based eddy identification algorithm is employed to derive the mesoscale eddy information from SSH data. Totally more than 5500 eddies are detected, belonging to 2583 eddy tracks. Statistics suggest that eddies generate over the entire Red Sea, with two regions in the central basin of high eddy frequency. 76% of the detected eddies have a radius ranging from 40km to 100km, of which both intensity and absolute vorticity decrease with eddy radius. The average eddy lifespan is about 5 weeks, and eddies with longer lifespan tend to have larger radius but less intensity. Different deformation rate exists between anticyclonic eddies (AEs) and cyclonic eddies (CEs), those eddies with higher intensity appear to be less deformed and more circular. Inspection of the 84 long-lived eddies suggests the AEs tend to move a little more northward than CEs. AE generation during summer is obviously lower than that during other seasons, while CE generation is higher during spring and summer. Other features of AEs and CEs are similar with both vorticity and intensity reaching the summer peaks in August and winter peaks in January. Inter-annual variability reveals that the eddies in the Red Sea are isolated from the global event. The eddy property tendencies are different from the south and north basin, both of which exhibit a two-year cycle. Showing a correlation coefficient of -0.91, Brunt–Väisälä frequency is negatively correlated with eddy kinetic energy (EKE), which results from AE activities in the high eddy frequency region. Climatological vertical velocity shear variation is identical with EKE except in the autumn, suggesting the

  20. Permanent Magnet Eddy Current Loss Analysis of a Novel Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Lu, Kaiyuan; Ye, Yunyue

    2012-01-01

    In this paper, a new motor integrated permanent magnet gear (MIPMG) is discussed. The focus is on eddy current loss analysis associated to permanent magnets (PMs). A convenient model of MIPMG is provided based on 2-D field-motion coupled time-stepping finite element method for transient eddy...... current analysis. The model takes the eddy current effect of PMs into account in determination of the magnetic field in the air-gap and in the magnet regions. The eddy current losses generated in the magnets are properly interpreted. Design improvements for reducing the eddy current losses are suggested...

  1. Quantification of surface energy fluxes from a small water body using scintillometry and eddy covariance

    DEFF Research Database (Denmark)

    McGloin, Ryan; McGowan, Hamish; McJannet, David

    2014-01-01

    Accurate quantification of evaporation from small water storages is essential for water management and planning, particularly in water-scarce regions. In order to ascertain suitable methods for direct measurement of evaporation from small water bodies, this study presents a comparison of eddy......% greater than eddy covariance measurements. We suggest possible reasons for this difference and provide recommendations for further research for improving measurements of surface energy fluxes over small water bodies using eddy covariance and scintillometry. Key Points Source areas for Eddy covariance...... and scintillometry were on the water surface Reasonable agreement was shown between the sensible heat flux measurements Scintillometer estimates of latent heat flux were greater than eddy covariance...

  2. A comparison of methane emission measurements using eddy covariance and manual and automated chamber-based techniques in Tibetan Plateau alpine wetland

    International Nuclear Information System (INIS)

    Yu, Lingfei; Wang, Hao; Wang, Guangshuai; Song, Weimin; Huang, Yao; Li, Sheng-Gong; Liang, Naishen; Tang, Yanhong; He, Jin-Sheng

    2013-01-01

    Comparing of different CH 4 flux measurement techniques allows for the independent evaluation of the performance and reliability of those techniques. We compared three approaches, the traditional discrete Manual Static Chamber (MSC), Continuous Automated Chamber (CAC) and Eddy Covariance (EC) methods of measuring the CH 4 fluxes in an alpine wetland. We found a good agreement among the three methods in the seasonal CH 4 flux patterns, but the diurnal patterns from both the CAC and EC methods differed. While the diurnal CH 4 flux variation from the CAC method was positively correlated with the soil temperature, the diurnal variation from the EC method was closely correlated with the solar radiation and net CO 2 fluxes during the daytime but was correlated with the soil temperature at nighttime. The MSC method showed 25.3% and 7.6% greater CH 4 fluxes than the CAC and EC methods when measured between 09:00 h and 12:00 h, respectively. -- Highlights: •Chamber and eddy covariance methods showed similar seasonal CH 4 flux patterns. •Chamber and eddy covariance methods showed different diurnal CH 4 flux patterns. •Static chamber methods gave a higher magnitude of CH 4 flux. -- The chamber-based methods and the eddy covariance method showed similar seasonal CH 4 flux patterns, but the manual static chamber method resulted in a higher CH 4 flux measurement

  3. Development of eddy current sensor for detecting defect on ferromagnetic material

    International Nuclear Information System (INIS)

    Choi, Duck Su; Lee, Hyang Beom

    2002-01-01

    In this paper, the eddy current sensor is developed for observing the ability of detecting defect on ferromagnetic material with variation of frequency and velocity. In order to research the characteristics on eddy current sensor. The circuit which is designed for processing detected voltage is developed and differential frequency is used for eddy current sensor to detect defect with variation of frequency. The ability of eddy current sensor to detect defects is studied with variation of velocity adjusted by rotating the circular plate. This study shows that the ability of eddy current sensor for detecting defect is increased and decreased by frequency. This fact means that the sensor has its best ability at a certain frequency. And the ability of eddy current sensor by velocity is decreased by increased velocity. Therefore, the eddy current sensor has to be developed with consideration of its operation velocity and frequency.

  4. Highlights from Johannesburg, Gauteng Province, South Africa

    Science.gov (United States)

    2002-01-01

    Although the extraction of mineral wealth has been the major influence in the history of Johannesburg and the surrounding Witwatersrand regions (with about 45% of all gold ever mined coming from there), the discovery of now-famous hominid fossils at the Sterkfontein Caves, and the convening of the world's largest-ever conference on environment and development, are setting a new stage for the future. The United Nations began the second Development and Environment Conference in Johannesburg on August 26, 2002. This meeting addresses the implementation of international goals to fight poverty and protect the global environment that were established at the first such conference held in Rio de Janeiro in 1992. The Johannesburg summit involves about forty thousand participants, and perhaps 100 world leaders. One of several official opening ceremonies for the conference was held at the Sterkfontein Caves to recognize the outstanding universal value of the paleo-anthropological fossils found there.These views from the Multi-angle Imaging SpectroRadiometer (MISR) highlight a number of the land use, vegetation, and geological features found within Gauteng Province (including the urban center of Johannesburg and the capital city Pretoria) and parts of the North West and Free State Provinces. The image on the right displays vegetation in red hues and is a false-color view utilizing data from MISR's near-infrared, red and blue bands. Both the natural-color view (left) and the false-color version were acquired by MISR's nadir camera on June 16, 2002. The urban areas appear as gray-colored pixels in the natural-color view, and exhibit colors corresponding with the relative abundance of vegetation found in the urban parts of this arid region.The mountains trending east-west near the center of the images extend from Pretoria in the east to Rustenberg in the west. These ranges, the Magaliesberg and Witwatersberg, separate the low-lying, hotter bushveld to the north from the cooler

  5. Contribution of mesoscale eddies to Black Sea ventilation

    Science.gov (United States)

    Capet, Arthur; Mason, Evan; Pascual, Ananda; Grégoire, Marilaure

    2017-04-01

    The shoaling of the Black Sea oxycline is one of the most urgent environmental issues in the Black Sea. The permanent oxycline derives directly from the Black Sea permanent stratification and has shoaled alarmingly in the last decades, due to a shifting balance between oxygen consumption and ventilation processes (Capet et al. 2016). The understanding of this balance is thus of the utmost importance and requires to quantify 1) the export of nutrients and organic materials from the shelf regions to the open sea and 2) the ventilation processes. These two processes being influenced by mesoscale features, it is critical to understand the role of the semi-permanent mesoscale structures in horizontal (center/periphery) and vertical (diapycnal and isopycnal) exchanges. A useful insight can be obtained by merging observations from satellite altimeter and in situ profilers (ARGO). In such composite analyses, eddies are first automatically identified and tracked from altimeter data (Mason et al. 2014, py-eddy-tracker). Vertical ARGO profiles are then expressed in terms of their position relative to eddy centers and radii. Derived statistics indicate how consistently mesoscale eddies alter the vertical structure, and provide a deeper understanding of the associated horizontal and vertical fluxes. However, this data-based approach is limited in the Black Sea due to the lower quality of gridded altimetric products in the vicinity of the coast, where semi-permanent mesoscale structures prevail. To complement the difficult analysis of this sparse dataset, a compositing methodology. is also applied to model outputs from the 5km GHER-BHAMBI Black Sea implementation (CMEMS BS-MFC). Characteristic biogeochemical anomalies associated with eddies in the model are analyzed per se, and compared to the observation-based analysis. Capet, A., Stanev, E. V., Beckers, J.-M., Murray, J. W., and Grégoire, M.: Decline of the Black Sea oxygen inventory, Biogeosciences, 13, 1287-1297, doi:10

  6. Determining Confounding Sensitivities In Eddy Current Thin Film Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gros, Ethan; Udpa, Lalita; Smith, James A.; Wachs, Katelyn

    2016-07-01

    Determining Confounding Sensitivities In Eddy Current Thin Film Measurements Ethan Gros, Lalita Udpa, Electrical Engineering, Michigan State University, East Lansing MI 48824 James A. Smith, Experiment Analysis, Idaho National Laboratory, Idaho Falls ID 83415 Eddy current (EC) techniques are widely used in industry to measure the thickness of non-conductive films on a metal substrate. This is done using a system whereby a coil carrying a high-frequency alternating current is used to create an alternating magnetic field at the surface of the instrument's probe. When the probe is brought near a conductive surface, the alternating magnetic field will induce ECs in the conductor. The substrate characteristics and the distance of the probe from the substrate (the coating thickness) affect the magnitude of the ECs. The induced currents load the probe coil affecting the terminal impedance of the coil. The measured probe impedance is related to the lift off between coil and conductor as well as conductivity of the test sample. For a known conductivity sample, the probe impedance can be converted into an equivalent film thickness value. The EC measurement can be confounded by a number of measurement parameters. It is the goal of this research to determine which physical properties of the measurement set-up and sample can adversely affect the thickness measurement. The eddy current testing is performed using a commercially available, hand held eddy current probe (ETA3.3H spring loaded eddy probe running at 8 MHz) that comes with a stand to hold the probe. The stand holds the probe and adjusts the probe on the z-axis to help position the probe in the correct area as well as make precise measurements. The signal from the probe is sent to a hand held readout, where the results are recorded directly in terms of liftoff or film thickness. Understanding the effect of certain factors on the measurements of film thickness, will help to evaluate how accurate the ETA3.3H spring

  7. Eddy Mediated Nutrient Pattern in the North Eastern Arabian Sea

    Science.gov (United States)

    Thachaparambil, M.; Moolakkal Antony, R.; B R, S.; V N, S.; N, C.; M, S.

    2016-02-01

    A Cold Core Eddy (CCE) mediated nutrient pattern in the North Eastern Arabian Sea (NEAS) is explained based on in situ measurments during March 2013 onboard FORV Sagar Sampada which was not reported earlier in the area. Samples for physical, chemical and biological parameters were collected in 5 stations along the diameter of the eddy and following standard protocols. The core of the CCE is identified at 21°20.38'N; 66°30.68'E with a diameter of 120Km. Earlier studies explaining the process and the forcing mechanism of the particular eddy records that, the eddy is short term (1-3 months) and is regular during the season. Surface waters were well oxygenated (>4.8 ml L-1) in the core. Surface value of nutrients viz., Nitrate, Nitrite, Silicate and phosphate in the core regions was 0.9µM, 0.01 µM, 0.5 µM and 0.7 µM respectively indicating upwelling in the core. Spring intermonsoon (SIM) is generally termed as a transition period between the active winter and summer seasons and as per earlier studies, high biological production and the regularly occurring Noctilica bloom is supported by the nutrient loading due to convective mixing during winter as well as regenerated production. However, present observations shows that, nutrient pumping due to the upwelling associated with the CCE also contributes for sustaining high biological production and are evident in the Chl a and mesozooplankton biovolume which records values of 4.35mg/m3 and 1.09ml/m3 respectively in the core. An intense Noctiluca blooms observed in the western flank of the eddy (Chl a 13.25 mg/m3; cell density 5.8×106 cells/litre), where Nitrate concentration records 1.04µM explains the role of such mesoscale processes in the sustenance of the HAB events. While eastern flank of the CCE showed typical open ocean condition of the season showing Nitrate 0.08µM; Chl a 0.23mg/m3; and phytoplankton cell density as 421 cells/litre. Keywords: Cold core eddy, nutrients, NEAS, SIM, biological production

  8. Practical Application of Eddy Currents Generated by Wind

    International Nuclear Information System (INIS)

    Dirba, I; Kleperis, J

    2011-01-01

    When a conductive material is subjected to time-varying magnetic fluxes, eddy (Foucault) currents are generated in it and magnetic field of opposite polarity as the applied one arises. Due to the internal resistance of the conductive material, the eddy currents will be dissipated into heat (Joule heating). Conventional domestic water heaters utilize gas burners or electric resistance heating elements to heat the water in the tank and substantial part of the energy to use for it is wasted. In this paper the origin of electromagnetic induction heat generated by wind turbine in special heat exchange camera connected to water boiler is discussed and material evaluation performed using mathematical modelling (comparing the 2D finite element model with analytical and numerical calculation results).

  9. Practical Application of Eddy Currents Generated by Wind

    Science.gov (United States)

    Dirba, I.; Kleperis, J.

    2011-06-01

    When a conductive material is subjected to time-varying magnetic fluxes, eddy (Foucault) currents are generated in it and magnetic field of opposite polarity as the applied one arises. Due to the internal resistance of the conductive material, the eddy currents will be dissipated into heat (Joule heating). Conventional domestic water heaters utilize gas burners or electric resistance heating elements to heat the water in the tank and substantial part of the energy to use for it is wasted. In this paper the origin of electromagnetic induction heat generated by wind turbine in special heat exchange camera connected to water boiler is discussed and material evaluation performed using mathematical modelling (comparing the 2D finite element model with analytical and numerical calculation results).

  10. Practical Application of Eddy Currents Generated by Wind

    Energy Technology Data Exchange (ETDEWEB)

    Dirba, I; Kleperis, J, E-mail: imants.dirba@gmail.com [Institute of Solid State Physics of University of Latvia, 8 Kengaraga Street, Riga, LV-1063 (Latvia)

    2011-06-23

    When a conductive material is subjected to time-varying magnetic fluxes, eddy (Foucault) currents are generated in it and magnetic field of opposite polarity as the applied one arises. Due to the internal resistance of the conductive material, the eddy currents will be dissipated into heat (Joule heating). Conventional domestic water heaters utilize gas burners or electric resistance heating elements to heat the water in the tank and substantial part of the energy to use for it is wasted. In this paper the origin of electromagnetic induction heat generated by wind turbine in special heat exchange camera connected to water boiler is discussed and material evaluation performed using mathematical modelling (comparing the 2D finite element model with analytical and numerical calculation results).

  11. Computation of transient 3-D eddy current in nonmagnetic conductor

    International Nuclear Information System (INIS)

    Yeh, H.T.

    1978-01-01

    A numerical procedure was developed to solve transient three-dimensional (3-D) eddy current problems for nonmagnetic conductor. Integral equation formulation in terms of vector potential is used to simplify the matching of boundary conditions. The resulting equations and their numerical approximation were shown to be singular and to require special handling. Several types of symmetries were introduced. They not only reduce the number of algebraic equations to be solved, but also modify the nature of the equations and render them nonsingular. Temporal behavior was obtained with the Runge-Kutta method. The program is tested in several examples of eddy currents for its spatial and temporal profiles, shielding, boundary surface effects, and application of various symmetry options

  12. Numeral eddy current sensor modelling based on genetic neural network

    International Nuclear Information System (INIS)

    Yu Along

    2008-01-01

    This paper presents a method used to the numeral eddy current sensor modelling based on the genetic neural network to settle its nonlinear problem. The principle and algorithms of genetic neural network are introduced. In this method, the nonlinear model parameters of the numeral eddy current sensor are optimized by genetic neural network (GNN) according to measurement data. So the method remains both the global searching ability of genetic algorithm and the good local searching ability of neural network. The nonlinear model has the advantages of strong robustness, on-line modelling and high precision. The maximum nonlinearity error can be reduced to 0.037% by using GNN. However, the maximum nonlinearity error is 0.075% using the least square method

  13. Eddy current calculations for the Tore Supra toroidal field magnet

    International Nuclear Information System (INIS)

    Blum, J.

    1983-01-01

    An outline is given of the calculation of the eddy currents in the magnetic structures of a Tokamak, which can be assimilated to thin conductors, so that the three-dimensional problem can be reduced mathematically to a two-dimensional one, the variables being two orthogonal coordinates of the considered surface. A finite element method has been used in order to treat the complicated geometry of the set of the 18 toroidal field coil casings and mechanical structures of Tore Supra. This eddy current code has been coupled with an axisymmetric equilibrium code in order to simulate typical phases of a Tokamak discharge (plasma current rise, additional heating, disruption, cleaning discharge) and the losses in the toroidal field magnet have thus been calculated. (author)

  14. Quality and Reliability of Large-Eddy Simulations

    CERN Document Server

    Meyers, Johan; Sagaut, Pierre

    2008-01-01

    Computational resources have developed to the level that, for the first time, it is becoming possible to apply large-eddy simulation (LES) to turbulent flow problems of realistic complexity. Many examples can be found in technology and in a variety of natural flows. This puts issues related to assessing, assuring, and predicting the quality of LES into the spotlight. Several LES studies have been published in the past, demonstrating a high level of accuracy with which turbulent flow predictions can be attained, without having to resort to the excessive requirements on computational resources imposed by direct numerical simulations. However, the setup and use of turbulent flow simulations requires a profound knowledge of fluid mechanics, numerical techniques, and the application under consideration. The susceptibility of large-eddy simulations to errors in modelling, in numerics, and in the treatment of boundary conditions, can be quite large due to nonlinear accumulation of different contributions over time, ...

  15. Mechanism of cavitation damage and structure of a cavitating eddy

    International Nuclear Information System (INIS)

    Efimov, A.V.; Vorob'ev, G.A.; Filenko, Yu.I.; Petrov, K.N.

    1976-01-01

    As a result of experimental studies of the structure of a cavitating eddy and the action of single cavitation bubbles on a solid surface the assumption of double nature of cavitation damage forces depending on its regimes was made. The first type of the damage forces is shock waves, appearing around collapsing spherical bubble, the second type is hydraulic impacts of microjets making a hole in a collapsing aspherical bubble. The outward appearance of single microdents differs from each other. The damage of the first type is accompanied by corrosion. The cavitation erosion intensity of the damage of the first type exceeds that of the damage of the second type by one order of magnitude. The values of the porosity of a cavitation eddy, the bubble concentration and the distance between them, the bubble distribution according to the size and the form for the initial cavitation stage are given from holographic investigations

  16. Eddy current probe development based on a magnetic sensor array

    International Nuclear Information System (INIS)

    Vacher, F.

    2007-06-01

    This research deals with in the study of the use of innovating magnetic sensors in eddy current non destructive inspection. The author reports an analysis survey of magnetic sensor performances. This survey enables the selection of magnetic sensor technologies used in non destructive inspection. He presents the state-of-the-art of eddy current probes exploiting the qualities of innovating magnetic sensors, and describes the methods enabling the use of these magnetic sensors in non destructive testing. Two main applications of innovating magnetic sensors are identified: the detection of very small defects by means of magneto-resistive sensors, and the detection of deep defects by means of giant magneto-impedances. Based on the use of modelling, optimization, signal processing tools, probes are manufactured for these both applications

  17. Electric transport in the Netherlands. Highlights 2012; Elektrisch vervoer in Nederland. Highlights 2012

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-03-15

    Businesses, social and educational institutions and governmental institutes work together to accelerate electric transport and to discover and exploit economic opportunities. In 2012, many activities were carried out and results achieved, of which the highlights are presented in this brochure [Dutch] Bedrijfsleven, maatschappelijke- en kennisinstellingen en overheden werken samen aan versnelling van elektrisch vervoer en het ontdekken en benutten van economische kansen. In 2012 werden veel activiteiten uitgevoerd en resultaten geboekt, waarvan in deze brochure verslag wordt gedaan.

  18. Automatic tracking of dynamical evolutions of oceanic mesoscale eddies with satellite observation data

    Science.gov (United States)

    Sun, Liang; Li, Qiu-Yang

    2017-04-01

    The oceanic mesoscale eddies play a major role in ocean climate system. To analyse spatiotemporal dynamics of oceanic mesoscale eddies, the Genealogical Evolution Model (GEM) based on satellite data is developed, which is an efficient logical model used to track dynamic evolution of mesoscale eddies in the ocean. It can distinguish different dynamic processes (e.g., merging and splitting) within a dynamic evolution pattern, which is difficult to accomplish using other tracking methods. To this end, a mononuclear eddy detection method was firstly developed with simple segmentation strategies, e.g. watershed algorithm. The algorithm is very fast by searching the steepest descent path. Second, the GEM uses a two-dimensional similarity vector (i.e. a pair of ratios of overlap area between two eddies to the area of each eddy) rather than a scalar to measure the similarity between eddies, which effectively solves the ''missing eddy" problem (temporarily lost eddy in tracking). Third, for tracking when an eddy splits, GEM uses both "parent" (the original eddy) and "child" (eddy split from parent) and the dynamic processes are described as birth and death of different generations. Additionally, a new look-ahead approach with selection rules effectively simplifies computation and recording. All of the computational steps are linear and do not include iteration. Given the pixel number of the target region L, the maximum number of eddies M, the number N of look-ahead time steps, and the total number of time steps T, the total computer time is O (LM(N+1)T). The tracking of each eddy is very smooth because we require that the snapshots of each eddy on adjacent days overlap one another. Although eddy splitting or merging is ubiquitous in the ocean, they have different geographic distribution in the Northern Pacific Ocean. Both the merging and splitting rates of the eddies are high, especially at the western boundary, in currents and in "eddy deserts". GEM is useful not only for

  19. Towards a Moon Village : Community Workshops Highlights

    Science.gov (United States)

    Foing, Bernard H.

    2016-07-01

    . References: [1] http://sci.esa.int/ilewg/ and https://ildwg.wordpress.com/ [2] Foing B. Moon exploration highlights and Moon Village introduction. [3] Young Lunar Explorers Report ESTEC Moon village sessions with community and young professionals.

  20. Progress realized by numerized Eddy current checking-chains

    International Nuclear Information System (INIS)

    Guerin, F.; Blanchet, A.

    1985-01-01

    Until the last ten years , the tubes of the Steam Generators of the Nuclear Stations were inspected by means of Eddy Current with analogical checkings-chains. HBS Company has perfected a numerized checking-chain allowing transmission up to 300 m of the E.C. signals. In a near future, it will be then possible to do periodical inspections of Steam Generators from cabins located out of the reactor building [fr

  1. The TS 600: automatic control system for eddy currents

    International Nuclear Information System (INIS)

    Poulet, J.P.

    1986-10-01

    In the scope of fabrication and in service inspection of the PWR steam generator tubing bendle, FRAMATOME developed an automatic Eddy Current testing system: TS600. Based on a mini-computer, TS600 allows to digitize, to store and to process data in various ways, so it is possible to perform several kinds of inspection: conventional inservice inspection, roll area profilometry...... TS600 can also be used to develop new methods of examination [fr

  2. Multifrequency eddy current testing of helical tubes of steam generators

    International Nuclear Information System (INIS)

    Pigeon, M.; David, B.

    1983-06-01

    In the event of a water-sodium reaction in a steam-generator of a fast breeder reactor, it is necessary to test the tubes close to the leak to evaluate the damage. In SUPERPHENIX, the tubes are about 100m long and are coiled on a dead body. This report describes the equipment and the technic to test such tubes with multifrequency eddy current technics [fr

  3. Formation of thermal eddies during rf heating of plasma

    International Nuclear Information System (INIS)

    Motley, R.W.; Hooke, W.M.; Anania, G.

    1979-07-01

    Moderate power (approx.1 kW) excitation of lower hybrid waves in a linear plasma column is found to increase the reflectivity of the phased waveguide exciter and to change the vertical position of the resonance cone. Probing of the plasma near the mouth of the waveguide reveals that the increased reflection results from an undulation in the plasma surface. We present evidence that this surface distortion is driven by thermal eddies associated with asymmetrical electron heating

  4. The integral equation method applied to eddy currents

    International Nuclear Information System (INIS)

    Biddlecombe, C.S.; Collie, C.J.; Simkin, J.; Trowbridge, C.W.

    1976-04-01

    An algorithm for the numerical solution of eddy current problems is described, based on the direct solution of the integral equation for the potentials. In this method only the conducting and iron regions need to be divided into elements, and there are no boundary conditions. Results from two computer programs using this method for iron free problems for various two-dimensional geometries are presented and compared with analytic solutions. (author)

  5. Large Eddy Simulation of stratified flows over structures

    OpenAIRE

    Brechler J.; Fuka V.

    2013-01-01

    We tested the ability of the LES model CLMM (Charles University Large-Eddy Microscale Model) to model the stratified flow around three dimensional hills. We compared the quantities, as the height of the dividing streamline, recirculation zone length or length of the lee waves with experiments by Hunt and Snyder[3] and numerical computations by Ding, Calhoun and Street[5]. The results mostly agreed with the references, but some important differences are present.

  6. Large Eddy Simulation of stratified flows over structures

    Directory of Open Access Journals (Sweden)

    Brechler J.

    2013-04-01

    Full Text Available We tested the ability of the LES model CLMM (Charles University Large-Eddy Microscale Model to model the stratified flow around three dimensional hills. We compared the quantities, as the height of the dividing streamline, recirculation zone length or length of the lee waves with experiments by Hunt and Snyder[3] and numerical computations by Ding, Calhoun and Street[5]. The results mostly agreed with the references, but some important differences are present.

  7. Large Eddy Simulation of stratified flows over structures

    Science.gov (United States)

    Fuka, V.; Brechler, J.

    2013-04-01

    We tested the ability of the LES model CLMM (Charles University Large-Eddy Microscale Model) to model the stratified flow around three dimensional hills. We compared the quantities, as the height of the dividing streamline, recirculation zone length or length of the lee waves with experiments by Hunt and Snyder[3] and numerical computations by Ding, Calhoun and Street[5]. The results mostly agreed with the references, but some important differences are present.

  8. Eddy current modeling in linear and nonlinear multifilamentary composite materials

    Science.gov (United States)

    Menana, Hocine; Farhat, Mohamad; Hinaje, Melika; Berger, Kevin; Douine, Bruno; Lévêque, Jean

    2018-04-01

    In this work, a numerical model is developed for a rapid computation of eddy currents in composite materials, adaptable for both carbon fiber reinforced polymers (CFRPs) for NDT applications and multifilamentary high temperature superconductive (HTS) tapes for AC loss evaluation. The proposed model is based on an integro-differential formulation in terms of the electric vector potential in the frequency domain. The high anisotropy and the nonlinearity of the considered materials are easily handled in the frequency domain.

  9. Eddy current testing system for bottom mounted instrumentation welds

    OpenAIRE

    Kobayashi Noriyasu; Ueno Souichi; Suganuma Naotaka; Oodake Tatsuya; Maehara Takeshi; Kasuya Takashi; Ichikawa Hiroya

    2015-01-01

    The capability of eddy current testing (ECT) for the bottom mounted instrumentation (BMI) weld area of reactor vessel in a pressurized water reactor was demonstrated by the developed ECT system and procedure. It is difficult to position and move the probe on the BMI weld area because the area has complexly curved surfaces. The space coordinates and the normal vectors at the scanning points were calculated as the scanning trajectory of probe based on the measured results of surface shape on th...

  10. Performance demonstration requirements for eddy current steam generator tube inspection

    International Nuclear Information System (INIS)

    Kurtz, R.J.; Heasler, P.G.; Anderson, C.M.

    1992-10-01

    This paper describes the methodology used for developing performance demonstration tests for steam generator tube eddy current (ET) inspection systems. The methodology is based on statistical design principles. Implementation of a performance demonstration test based on these design principles will help to ensure that field inspection systems have a high probability of detecting and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented. Probability of detection and flaw sizing tests are described

  11. Surface inspection technique with an eddy current testing array probe

    International Nuclear Information System (INIS)

    Nishimizu, Akira; Endo, Hisashi; Tooma, Masahiro; Otani, Kenichi; Ouchi, Hirofumi; Yoshida, Isao; Nonaka, Yoshio

    2010-01-01

    An eddy current testing (ECT) system has been developed for inspecting weld surfaces of components in the reactor pressure vessel of nuclear plants. The system can be applied to curved surfaces with an ECT array probe, it can discriminate flaws from other signal factors by using a combination of arrayed coils signal-phase. The system is applied to a mock-up of core internal components and the signal discrimination using the signal-phase clearly separated flaw and noise signals. (author)

  12. Sensitivity analysis of eddy current sensors using computational simulation

    OpenAIRE

    Neugebauer, Reimund; Drossel, W.-G.; Mainda, P.; Roscher, H.-J.; Wolf, K.; Kroschk, M.

    2011-01-01

    Eddy current sensors can detect the position and movement of metal parts without direct contact. The magnetic fields of these sensors can penetrate protective metal enclosures when designed and applied appropriately. Thus particularly robust solutions for industrial applications are possible, e.g. tracking objects electrically like conductive or ferromagnetic work pieces (device currently being tested) during a treatment process under difficult production conditions. The disadvantage of a tes...

  13. Eddy current testing probe optimization using a parallel genetic algorithm

    Directory of Open Access Journals (Sweden)

    Dolapchiev Ivaylo

    2008-01-01

    Full Text Available This paper uses the developed parallel version of Michalewicz's Genocop III Genetic Algorithm (GA searching technique to optimize the coil geometry of an eddy current non-destructive testing probe (ECTP. The electromagnetic field is computed using FEMM 2D finite element code. The aim of this optimization was to determine coil dimensions and positions that improve ECTP sensitivity to physical properties of the tested devices.

  14. Three-axis orthogonal transceiver coil for eddy current sounding

    Science.gov (United States)

    Sukhanov, D.; Zavyalova, K.; Goncharik, M.

    2017-08-01

    We propose the new structure of three-axis transceiver magnetic-induction coil for eddy current probing. Due to the orientation of the coils, the direct signal from the transmitting coil to the receiving coil is minimized, which provided a high dynamic range. Sensitivity in all directions is provided by combining coils of different orientations. Numerical simulation and experimental studies of such a system have been carried out and confirmed the applicability of the proposed method and the mathematical model.

  15. Assessment of defects in ferromagnetic metals with eddy currents

    OpenAIRE

    Oaten, Susan Rosemary

    1989-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. A study was made to identify and size surface breaking defects in ferromagnetic materials with eddy currents, whilst eliminating unwanted signals due to changes in magnetic permeability and probe lift-off. The former was overcome by the use of high frequencies and the latter by utilising the lift-off to characterise the defects. The lift- off or "touch" method was shown to be advantageous in ...

  16. The Use of Mesoscale Eddies and Gulf Stream Meanders by White Sharks Carcharodon carcharias

    Science.gov (United States)

    Gaube, P.; Thorrold, S.; Braun, C.; McGillicuddy, D. J., Jr.; Lawson, G. L.; Skomal, G. B.

    2016-02-01

    Large pelagic fishes like sharks, tuna, swordfish, and billfish spend a portion of their lives in the open ocean, yet their spatial distribution in this vast habitat remains relatively unknown. Mesoscale ocean eddies, rotating vortices with radius scales of approximately 100 km, structure open ocean ecosystems from primary producers to apex predators by influencing nutrient distributions and transporting large trapped parcels of water over long distances. Recent advances in both the tagging and tracking of marine animals combined with improved detection and tracking of mesoscale eddies has shed some light on the oceanographic features influencing their migrations. Here we show that white sharks use the interiors of anticyclonic and cyclonic eddies differently, a previously undocumented behavior. While swimming in warm, subtropical water, white sharks preferentially inhabit anticyclonic eddies compared to cyclonic eddies. In the vicinity of the Gulf Stream, the depth and duration of dives recorded by an archival temperature- and depth-recording tag affixed to a large female are shown to be significantly deeper and longer in anticyclonic eddies compared to those in cyclonic eddies. This asymmetry is linked to positive subsurface temperature anomalies generated by anticyclonic eddies that are more than 7 degrees C warmer than cyclonic eddies, thus reducing the need for these animals to expend as much energy regulating their internal temperature. In addition, anticyclonic eddies may be regions of enhance foraging success, as suggested by a series of acoustics surveys in the North Atlantic which indicated elevated mesopelagic fish biomass in anticyclones compared to cyclones.

  17. Large eddy simulation of turbulent and stably-stratified flows

    International Nuclear Information System (INIS)

    Fallon, Benoit

    1994-01-01

    The unsteady turbulent flow over a backward-facing step is studied by mean of Large Eddy Simulations with structure function sub grid model, both in isothermal and stably-stratified configurations. Without stratification, the flow develops highly-distorted Kelvin-Helmholtz billows, undergoing to helical pairing, with A-shaped vortices shed downstream. We show that forcing injected by recirculation fluctuations governs this oblique mode instabilities development. The statistical results show good agreements with the experimental measurements. For stably-stratified configurations, the flow remains more bi-dimensional. We show with increasing stratification, how the shear layer growth is frozen by inhibition of pairing process then of Kelvin-Helmholtz instabilities, and the development of gravity waves or stable density interfaces. Eddy structures of the flow present striking analogies with the stratified mixing layer. Additional computations show the development of secondary Kelvin-Helmholtz instabilities on the vorticity layers between two primary structures. This important mechanism based on baroclinic effects (horizontal density gradients) constitutes an additional part of the turbulent mixing process. Finally, the feasibility of Large Eddy Simulation is demonstrated for industrial flows, by studying a complex stratified cavity. Temperature fluctuations are compared to experimental measurements. We also develop three-dimensional un-stationary animations, in order to understand and visualize turbulent interactions. (author) [fr

  18. Validating eddy current array probes for inspecting steam generator tubes

    International Nuclear Information System (INIS)

    Sullivan, S.P.; Cecco, V.S.; Obrutsky, L.S.

    1997-01-01

    A CANDU nuclear reactor was shut down for over one year because steam generator (SG) tubes had failed with outer diameter stress-corrosion cracking (ODSCC) in the U-bend section. Novel, single-pass eddy current transmit-receive probes, denoted as C3, were successful in detecting all significant cracks so that the cracked tubes could be plugged and the unit restarted. Significant numbers of tubes with SCC were removed from a SG in order to validate the results of the new probe. Results from metallurgical examinations were used to obtain probability-of-detection (POD) and sizing accuracy plots to quantify the performance of this new inspection technique. Though effective, the above approach of relying on tubes removed from a reactor is expensive, in terms of both economic and radiation-exposure costs. This led to a search for more affordable methods to validate inspection techniques and procedures. Methods are presented for calculating POD curves based on signal-to-noise studies using field data. Results of eddy current scans of tubes with laboratory-induced ODSCC are presented with associated POD curves. These studies appear promising in predicting realistic POD curves for new inspection technologies. They are being used to qualify an improved eddy current array probe in preparation for field use. (author)

  19. Copepod behavior response to Burgers' vortex treatments mimicking turbulent eddies

    Science.gov (United States)

    Elmi, D.; Webster, D. R.; Fields, D. M.

    2017-11-01

    Copepods detect hydrodynamic cues in the water by their mechanosensory setae. We expect that copepods sense the flow structure of turbulent eddies in order to evoke behavioral responses that lead to population-scale distribution patterns. In this study, the copepods' response to the Burgers' vortex is examined. The Burgers' vortex is a steady-state solution of three-dimensional Navier-Stokes equations that allows us to mimic turbulent vortices at the appropriate scale and eliminate the stochastic nature of turbulence. We generate vortices in the laboratory oriented in the horizontal and vertical directions each with four intensity levels. The objective of including vortex orientation as a parameter in the study is to quantify directional responses that lead to vertical population distribution patterns. The four intensity levels correspond to target vortex characteristics of eddies corresponding to the typical dissipative vortices in isotropic turbulence with mean turbulent dissipation rates in the range of 0.002 to 0.25 cm2/s3. These vortices mimic the characteristics of eddies that copepods most likely encounter in coastal zones. We hypothesize that the response of copepods to hydrodynamic features depends on their sensory architecture and relative orientation with respect to gravity. Tomo-PIV is used to quantify the vortex circulation and axial strain rate for each vortex treatment. Three-dimensional trajectories of the copepod species Calanus finmarchicus are analyzed to examine their swimming kinematics in and around the vortex to quantify the hydrodynamic cues that trigger their behavior.

  20. Eddy current test of fin tubes for a heat exchanger

    International Nuclear Information System (INIS)

    KIm, Young Joo; Lee, Se Kyung; Chung, Min Hwa

    1992-01-01

    Eddy current probes were designed for the test of fin tubes. Fin tubes, often used for heat exchangers, have uneven outer and inner surfaces to enhance the heat emission. The surface roughness make it difficult to detect flaws employing eddy current test(ECT). In order to overcome the difficulties we performed two types of works, one is the delopment of ECT probes, and the other is the signal processing including fast Fourier transform and digital filtering. In the development of ECT probes, we adopted empirical design method. Our ECT probes for fin tubes are inside diameter type. And we are specially concerned about geometric features such as the widths of the coils composing an ECT probe. We fabricated four probes with various coil widths. Eddy current test was performed using those ECT probes on specimens with artificial flaws. After analyzing the output signals, we found that, in order for the effective testing, the width of a coil should be determined considering the pitch of the fins of a tube. And we also learned that the frequency filtering could improve the s/n ratio.

  1. Convection anomalies associated with warm eddy at the coastal area

    Science.gov (United States)

    Shi, R.; Wang, D.

    2017-12-01

    A possible correlation between a warm eddy and thunderstorms and convective precipitations are investigated at the coastal area in the northwestern South China Sea. Compared to the climatological mean in August from 2006 to 2013, an extreme enhancement of thunderstorm activities and precipitation rate are identified at the southern offshore area of Hainan island in August 2010 when a strong and long-live warm eddy was observed near the coastline at the same time. The 3 hourly satellite data (TRMM) indicate that the nocturnal convections is strong offshore and that could be responsible for the extreme positive anomalies of thunderstorms and rainfall in August 2010. The TRMM data also show a small reduction of thunderstorm activities and rainfall on the island in the afternoon. Meanwhile, the Weather Research and Forecasting (WRF) model was applied to simulate the change of rainfall in August 2010. The WRF simulation of rainfall rate is comparable with the observation results while there is some difference in the spatial distribution. The WRF simulation successfully captured the strong offshore rainfall and the diurnal variation of rainfall in August 2010. The WRF simulation indicated that the different convergence induced by sea/land breeze could be one essential reason for the adjustment of thunderstorms and rainfall in 2010. The substantial connection between sea/land breeze and upper layer heat content modified by the warm eddy is still on ongoing and will be reported in the future work.

  2. Eddy current inspection of steam generator tubing plugs

    International Nuclear Information System (INIS)

    Cullen, W.K.

    1990-01-01

    In response to the issues raised regarding the integrity of nuclear steam generator tubing plugs manufactured from certain heats of Inconel 600, Westinghouse engineers have developed, qualified and implemented an eddy current inspection system for the in-place assessment of these plugs. The heart of the system is a robotic and effector which delivers an eddy current sensor through the reduced diameter of the plug expander and actuates the coil to physical contact with the expanded inside bore of the plug. Once deployed, the eddy current sensor is rotated along a helical path to produce a detailed scan of the plug surface above the final position of the expander. This testing produces an isometric display of degradation due to primary water stress corrosion cracking, on the inside surface of the plug. To date, successful inspections have been conducted at two nuclear units with two different robotic delivery systems. While designed specifically for mechanical plugs with a bottle bore cavity, the inspection system can also be used for expanded straight bore plugs. Details of the inspection system along with a discussion of qualification activities and actual field results are presented in this paper

  3. Large eddy simulation of the subcritical flow over a V grooved circular cylinder

    International Nuclear Information System (INIS)

    Alonzo-García, A.; Gutiérrez-Torres, C. del C.; Jiménez-Bernal, J.A.

    2015-01-01

    Highlights: • We compared numerically the turbulent flow over a smooth circular cylinder and a V grooved cylinder in the subcritical regime. • Turbulence intensities in both streamwise and normal direction suffered attenuations. • The swirls structures on grooves peaks seemed to have a cyclic behavior. • The evolution of the flow inside grooves showed that swirls structures located in peaks suffered elongations in the normal direction. • The secondary vortex structures formed in the grooved cylinder near wake were smaller in comparison of the smooth cylinder flow. - Abstract: In this paper, a comparative numerical study of the subcritical flow over a smooth cylinder and a cylinder with V grooves (Re = 140,000) is presented. The implemented technique was the Large Eddy Simulation (LES), which according to Kolmogorov's theory, resolves directly the most energetic largest eddies and models the smallest and considered universal high frequency ones. The Navier-Stokes (N-S) equations were solved using the commercial software ANSYS FLUENT V.12.1, which applied the finite volume method (FVM) to discretize these equations in their unsteady and incompressible forms. The grid densities were 2.6 million cells and 13.5 million cells for the smooth and V grooved cylinder, respectively. Both meshes were composed of structured hexahedral cells and close to the wall of the cylinders, additional refinements were employed in order to obtain y +<5 values. All cases were simulated during at least 15 vortex shedding cycles with the aim of obtaining significant statistical data. Results: showed that for both cases (smooth and V grooved cylinder flow), the numerical code was capable of reproducing the most important physical quantities of the subcritical regime. Velocity distribution and turbulence intensity in the flow direction suffered a slight attenuation along the wake, as a consequence of grooves perturbation, which also caused an increase in the pressure coefficient

  4. Distribution of picoplankton in the northeastern South China Sea with special reference to the effects of the Kuroshio intrusion and the associated mesoscale eddies.

    Science.gov (United States)

    Li, Jiajun; Jiang, Xin; Li, Gang; Jing, Zhiyou; Zhou, Linbin; Ke, Zhixin; Tan, Yehui

    2017-07-01

    We investigated picoplankton distribution patterns and environmental variables along an east-to-west transect in the northeastern South China Sea (SCS) during late winter 2016, giving us the opportunity to examine the impacts of the Kuroshio intrusion and the associated eddies. The results indicated that the subsurface (50-75m) phytoplankton biomass chlorophyll (Chl a) maximum (SCM) disappeared and was replaced by higher Chl a in the middle part of the transect due to the impacts of the Kuroshio intrusion and mesoscale eddies. Both flow cytometry and pyrosequencing data revealed that picoplankton abundance and community structure were significantly influenced by perturbations in complex physical processes. Picoeukaryotes represented most of the total phytoplankton biomass, and their maximum abundance (>10 4 cellsmL -1 ) occurred within cyclonic eddy-affected regions (Stations 11 and 12), whereas the abundance of Prochlorococcus was the lowest in these regions. Prochlorococcus showed a higher abundance in the Kuroshio-affected area, while Synechococcus was mostly distributed at the upper well-lit depths, with its maximum abundance observed in surface waters (0-30m) adjacent to the cyclonic eddy center. Heterotrophic bacteria (HBA) displayed high abundance along the transect, consistent with the total phytoplankton biomass. Phylogenetic analysis revealed 26 bacterial phyla, with major components belonging to Proteobacteria, Cyanobacteria, Actinobacteria, and Bacteroidetes, as well as SAR406. Notably, relatively more Rhodobacterales, Flavobacteriales, Alteromonadales, and Vibrionales that were distributed in surface waters of the cyclonic eddy center were specifically associated with the phytoplankton (mainly picoeukaryotes) bloom. Our study highlights the impacts of the Kuroshio intrusion in regulating the microbial ecology of the northeastern SCS and the potential coupling between phytoplankton and bacteria. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Large Eddy Simulation of a thermal mixing tee in order to assess the thermal fatigue

    International Nuclear Information System (INIS)

    Galpin, J.; Simoneau, J.P.

    2011-01-01

    Highlights: → In this study, we perform a Large Eddy Simulation of a mixing tee, for which experimental thermal statistics are available. → A special methodology has been set up for comparing properly the fluctuations with the experiment. → A comparison between the Smagorinsky and the structure-function sub-grid scale model is achieved out. → Slight better predictions are obtained with the structure-function model. → The possibility to reduce the computational domain by prescribing synthetic turbulence at the inlet is tested. First results are encouraging and underline the advantage of considering this technique instead of a standard noise at the entrance of the domain. - Abstract: The present paper deals with thermal fatigue phenomenon, and more particularly with the numerical simulation using Large Eddy Simulation technique of a mixing tee, for which experimental thermal statistics are available. The sensitivity to the sub-grid scale closure is first evaluated by comparing the experimental statistics with the numerical results obtained via both the Smagorinsky and the structure-function models. Because of a difference of temporal resolution between the experiment and the simulation, the direct comparison of the fluctuations is not possible. Therefore, a methodology based on filtering the numerical results is proposed in order to achieve a proper comparison. The comparison of the numerical results with the experiment suggests that slight better predictions are obtained with the structure-function model even if the dependency of the results to the sub-grid scale model is low. Then, the possibility to reduce the fluid computational domain by prescribing synthetic turbulence at the inlet is tested. First results are encouraging and underline the advantage of considering this technique instead of a standard noise at the entrance of the domain. All the simulations are conducted with the commercial CFD code STAR-CD.

  6. Large-eddy simulation in a mixing tee junction: High-order turbulent statistics analysis

    International Nuclear Information System (INIS)

    Howard, Richard J.A.; Serre, Eric

    2015-01-01

    Highlights: • Mixing and thermal fluctuations in a junction are studied using large eddy simulation. • Adiabatic and conducting steel wall boundaries are tested. • Wall thermal fluctuations are not the same between the flow and the solid. • Solid thermal fluctuations cannot be predicted from the fluid thermal fluctuations. • High-order turbulent statistics show that the turbulent transport term is important. - Abstract: This study analyses the mixing and thermal fluctuations induced in a mixing tee junction with circular cross-sections when cold water flowing in a pipe is joined by hot water from a branch pipe. This configuration is representative of industrial piping systems in which temperature fluctuations in the fluid may cause thermal fatigue damage on the walls. Implicit large-eddy simulations (LES) are performed for equal inflow rates corresponding to a bulk Reynolds number Re = 39,080. Two different thermal boundary conditions are studied for the pipe walls; an insulating adiabatic boundary and a conducting steel wall boundary. The predicted flow structures show a satisfactory agreement with the literature. The velocity and thermal fields (including high-order statistics) are not affected by the heat transfer with the steel walls. However, predicted thermal fluctuations at the boundary are not the same between the flow and the solid, showing that solid thermal fluctuations cannot be predicted by the knowledge of the fluid thermal fluctuations alone. The analysis of high-order turbulent statistics provides a better understanding of the turbulence features. In particular, the budgets of the turbulent kinetic energy and temperature variance allows a comparative analysis of dissipation, production and transport terms. It is found that the turbulent transport term is an important term that acts to balance the production. We therefore use a priori tests to evaluate three different models for the triple correlation

  7. Observational Inferences of Lateral Eddy Diffusivity in the Halocline of the Beaufort Gyre

    Science.gov (United States)

    Meneghello, Gianluca; Marshall, John; Cole, Sylvia T.; Timmermans, Mary-Louise

    2017-12-01

    Using Ekman pumping rates mediated by sea ice in the Arctic Ocean's Beaufort Gyre (BG), the magnitude of lateral eddy diffusivities required to balance downward pumping is inferred. In this limit—that of vanishing residual-mean circulation—eddy-induced upwelling exactly balances downward pumping. The implied eddy diffusivity varies spatially and decays with depth, with values of 50-400 m2/s. Eddy diffusivity estimated using mixing length theory applied to BG mooring data exhibits a similar decay with depth and range of values from 100 m2/s to more than 600 m2/s. We conclude that eddy diffusivities in the BG are likely large enough to balance downward Ekman pumping, arresting the deepening of the gyre and suggesting that eddies play a zero-order role in buoyancy and freshwater budgets of the BG.

  8. Eddy-induced Sea Surface Salinity changes in the tropical Pacific

    Science.gov (United States)

    Delcroix, T. C.; Chaigneau, A.; Soviadan, D.; Boutin, J.

    2017-12-01

    We analyse the Sea Surface Salinity (SSS) signature of westward propagating mesoscale eddies in the tropical Pacific by collocating 5 years (2010-2015) of SMOS (Soil Moisture and Ocean Salinity) SSS and altimetry-derived sea level anomalies. The main characteristics of mesoscale eddies are first identified in SLA maps. Composite analyses in the Central and Eastern ITCZ regions then reveal regionally dependent impacts with opposite SSS anomalies for the cyclonic and anticyclonic eddies. In the Central region (where we have the largest meridional SSS gradient), we found dipole-like SSS changes with maximum anomalies on the leading edge of the eddy. In the Eastern region (where we have the largest near-surface vertical salinity gradient) we found monopole-like SSS changes with maximum anomalies in the eddy centre. These dipole/monopole patterns and the rotational sense of eddies suggest the dominant role of horizontal and vertical advection in the Central and Eastern ITCZ regions, respectively.

  9. The South China Sea Mesoscale Eddy Experiment (S-MEE) and Its Primary Findings

    Science.gov (United States)

    Zhang, Z.; Tian, J.; Zhao, W.; Qiu, B.

    2016-02-01

    South China Sea (SCS), the largest marginal sea in the northwestern Pacific, have strong eddy activities as revealed by both satellite and in situ observations. The 3D structures of the SCS mesoscale eddies and their lifecycles, including the generation and dissipation processes, are, however, still not well understood at present because of the lack of well-designed field observations. In order to address the above two scientific issues (3D structure and lifecycle of SCS mesoscale eddies), the SCS Mesoscale Eddy Experiment (S-MEE for short) was designed and conducted in the period from October 2013 to June 2014. As part of S-MEE, two bottom-anchored subsurface mooring arrays with one consisting of 10 moorings and the other 7 moorings, were deployed along the historical pathway of the mesoscale eddies in the northern SCS. All the moorings were equipped with ADCPs, RCMs, CTDs and temperature chains to make continues measurements of horizontal current velocity and temperature/salinity in the whole water column. During the S-MEE, a total of 5 distinct mesoscale eddies were observed to cross the mooring arrays, among which one anticyclonic and cyclonic eddy pair was fully captured by the mooring arrays. In addition to moored observations, we also conducted two transects across the center of the anticyclonic eddy and made high-resolution hydrographic and turbulent mixing measurements. Based on the data collected by the S-MEE and concurrent satellite-derived observations, we constructed the full-depth 3D structure of the eddy pair and analyzed its generation and dissipation mechanisms. We found that the eddies extend from the surface to the sea bottom and display prominent tilted structures in the vertical. By conducting an eddy energy budget analysis, we further identified that generation of submesoscale motions constitutes the dominant mechanism for the oceanic eddy dissipation.

  10. Current state and development trends of inspections of steam generator tubes by eddy currents method

    International Nuclear Information System (INIS)

    Kubis, S.; Herman, M.

    1988-01-01

    The requirements are presented for steam generator tube testing and the factors are discussed affecting the accuracy of measurement by the eddy currents method. The individual types of the eddy currents method are described, such as the single-frequency method, the multi-frequency method and the pulse eddy currents method. The demands are summed up on manipulator systems whose design is adapted to the steam generator configuration conditions. (E.S.). 5 figs., 16 possu

  11. Large eddy simulation of turbulent mixing in a T-junction

    International Nuclear Information System (INIS)

    Kim, Jung Woo

    2010-12-01

    In this report, large eddy simulation was performed in order to further improve our understanding the physics of turbulent mixing in a T-junction, which is recently regarded as one of the most important problems in nuclear thermal-hydraulics safety. Large eddy simulation technique and the other numerical methods used in this study were presented in Sec. 2, and the numerical results obtained from large eddy simulation were described in Sec. 3. Finally, the summary was written in Sec. 4

  12. Coupling between eddy currents and rigid body rotation: analysis, computation, and experiments

    International Nuclear Information System (INIS)

    Hua, T.Q.; Turner, L.R.

    1985-01-01

    Computation and experiment show that the coupling between eddy currents and the angular deflections resulting from those eddy currents can reduce electromagnetic effects such as forces, torques, and power dissipation to levels far less severe than would be predicted without regard for the coupling. This paper explores the coupling effects beyond the parameter range that has been explored experimentally, using analytical means and the eddy-current computer code EDDYNET. The paper also describes upcoming FELIX experiments with cantilevered beams

  13. Biogeochemical characteristics of a long-lived anticyclonic eddy in the eastern South Pacific Ocean

    Science.gov (United States)

    Cornejo D'Ottone, Marcela; Bravo, Luis; Ramos, Marcel; Pizarro, Oscar; Karstensen, Johannes; Gallegos, Mauricio; Correa-Ramirez, Marco; Silva, Nelson; Farias, Laura; Karp-Boss, Lee

    2016-05-01

    Mesoscale eddies are important, frequent, and persistent features of the circulation in the eastern South Pacific (ESP) Ocean, transporting physical, chemical and biological properties from the productive shelves to the open ocean. Some of these eddies exhibit subsurface hypoxic or suboxic conditions and may serve as important hotspots for nitrogen loss, but little is known about oxygen consumption rates and nitrogen transformation processes associated with these eddies. In the austral fall of 2011, during the Tara Oceans expedition, an intrathermocline, anticyclonic, mesoscale eddy with a suboxic ( 0.5 µM), suggesting that active denitrification occurred in this water mass. Using satellite altimetry, we were able to track the eddy back to its region of formation on the coast of central Chile (36.1° S, 74.6° W). Field studies conducted in Chilean shelf waters close to the time of eddy formation provided estimates of initial O2 and N2O concentrations of the ESSW source water in the eddy. By the time of its offshore sighting, concentrations of both O2 and N2O in the subsurface oxygen minimum zone (OMZ) of the eddy were lower than concentrations in surrounding water and "source water" on the shelf, indicating that these chemical species were consumed as the eddy moved offshore. Estimates of apparent oxygen utilization rates at the OMZ of the eddy ranged from 0.29 to 44 nmol L-1 d-1 and the rate of N2O consumption was 3.92 nmol L-1 d-1. These results show that mesoscale eddies affect open-ocean biogeochemistry in the ESP not only by transporting physical and chemical properties from the coast to the ocean interior but also during advection, local biological consumption of oxygen within an eddy further generates conditions favorable to denitrification and loss of fixed nitrogen from the system.

  14. 3-D analysis of eddy current in permanent magnet of interior permanent magnet motors

    International Nuclear Information System (INIS)

    Kawase, Yoshihiro; Yamaguchi, Tadashi; Fukanaga, Hiromu; Ito, Shokichi

    2002-01-01

    Interior permanent magnet motors are widely used in various fields. However, in high-speed operations, it is important to decrease the eddy current loss in the permanent magnet. In order to decrease the eddy current loss, we propose to divide the permanent magnet. In this paper, we clarified the effect of division of permanent magnet on the eddy current loss using the 3-D finite element method. (Author)

  15. Vortex stability in a multi-layer quasi-geostrophic model: application to Mediterranean Water eddies

    Energy Technology Data Exchange (ETDEWEB)

    Carton, Xavier; Ménesguen, Claire; Meunier, Thomas [Laboratoire de Physique des Oceans, UBO/IFREMER/CNRS/IRD, Brest (France); Sokolovskiy, Mikhail [Institute of Water Problems of the RAS, Moscow (Russian Federation); Aguiar, Ana, E-mail: xcarton@univ-brest.fr [Instituto Dom Luiz, Universidade de Lisboa, Lisbon (Portugal)

    2014-12-01

    The stability of circular vortices to normal mode perturbations is studied in a multi-layer quasi-geostrophic model. The stratification is fitted on the Gulf of Cadiz where many Mediterranean Water (MW) eddies are generated. Observations of MW eddies are used to determine the parameters of the reference experiment; sensitivity tests are conducted around this basic case. The objective of the study is two-fold: (a) determine the growth rates and nonlinear evolutions of unstable perturbations for different three-dimensional (3D) velocity structures of the vortices, (b) check if the different structure of our idealized vortices, mimicking MW cyclones and anticyclones, can induce different stability properties in a model that conserves parity symmetry, and apply these results to observed MW eddies. The linear stability analysis reveals that, among many 3D distributions of velocity, the observed eddies are close to maximal stability, with instability time scales longer than 100 days (these time scales would be less than 10 days for vertically more sheared eddies). The elliptical deformation is most unstable for realistic eddies (the antisymmetric one dominates for small eddies and the triangular one for large eddies); the antisymmetric mode is stronger for cyclones than for anticyclones. Nonlinear evolutions of eddies with radii of about 30 km, and elliptically perturbed, lead to their re-organization into 3D tripoles; smaller eddies are stable and larger eddies break into 3D dipoles. Horizontally more sheared eddies are more unstable and sustain more asymmetric instabilities. In summary, few differences were found between cyclone and anticyclone stability, except for strong horizontal velocity shears. (paper)

  16. Vortex stability in a multi-layer quasi-geostrophic model: application to Mediterranean Water eddies

    International Nuclear Information System (INIS)

    Carton, Xavier; Ménesguen, Claire; Meunier, Thomas; Sokolovskiy, Mikhail; Aguiar, Ana

    2014-01-01

    The stability of circular vortices to normal mode perturbations is studied in a multi-layer quasi-geostrophic model. The stratification is fitted on the Gulf of Cadiz where many Mediterranean Water (MW) eddies are generated. Observations of MW eddies are used to determine the parameters of the reference experiment; sensitivity tests are conducted around this basic case. The objective of the study is two-fold: (a) determine the growth rates and nonlinear evolutions of unstable perturbations for different three-dimensional (3D) velocity structures of the vortices, (b) check if the different structure of our idealized vortices, mimicking MW cyclones and anticyclones, can induce different stability properties in a model that conserves parity symmetry, and apply these results to observed MW eddies. The linear stability analysis reveals that, among many 3D distributions of velocity, the observed eddies are close to maximal stability, with instability time scales longer than 100 days (these time scales would be less than 10 days for vertically more sheared eddies). The elliptical deformation is most unstable for realistic eddies (the antisymmetric one dominates for small eddies and the triangular one for large eddies); the antisymmetric mode is stronger for cyclones than for anticyclones. Nonlinear evolutions of eddies with radii of about 30 km, and elliptically perturbed, lead to their re-organization into 3D tripoles; smaller eddies are stable and larger eddies break into 3D dipoles. Horizontally more sheared eddies are more unstable and sustain more asymmetric instabilities. In summary, few differences were found between cyclone and anticyclone stability, except for strong horizontal velocity shears. (paper)

  17. Impact of space dependent eddy mixing on large ocean circulation

    Science.gov (United States)

    Pradal, M. A. S.; Gnanadesikan, A.; Abernathey, R. P.

    2016-02-01

    Throughout the ocean, mesoscale eddies stir tracers such as heat, oxygen, helium, dissolved CO2, affecting their spatial distribution. Recent work (Gnanadesikan et al., 2013) showed that changes in eddy stirring could result in changes of the volume of hypoxic and anoxic waters, leading to drastic consequences for ocean biogeochemical cycles. The parameterization of mesocale eddies in global climate models (GCMs) is two parts, based on the formulations of Redi (1982) and Gent and McWilliams (1990) which are associated with mixing parameters ARedi and AGM respectively. Numerous studies have looked at the sensitivity of ESMs to changing AGM, either alone or in combination with an ARedi parameter taken to be equivalent to the value of the AGM. By contrast the impact of the Redi parameterization in isolation remains unexplored. In a previous article, Pradal and Gnanadesikan, 2014, described the sensitivity of the climate system to a six fold increase in the Redi parameter. They found that increasing the isopycnal mixing coefficient tended to warm the climate of the planet overall, through an increase of heat absorption linked to a destabilization of the halocline in subpolar regions (particularly the Southern Ocean). This previous work varied a globally constant Redi parameter from 400m2/s to 2400m2/s. New estimates from altimetry (Abernathey and Marshall, 2013) better constrain the spatial patterns and range for the ARedi parameter. Does such spatial variation matter, and if so, where does matter? Following Gnanadesikan et al. (2013) and Pradal and Gnanadesikan, 2014 this study examines this question with a suite of Earth System Models.

  18. An Extensible Processing Framework for Eddy-covariance Data

    Science.gov (United States)

    Durden, D.; Fox, A. M.; Metzger, S.; Sturtevant, C.; Durden, N. P.; Luo, H.

    2016-12-01

    The evolution of large data collecting networks has not only led to an increase of available information, but also in the complexity of analyzing the observations. Timely dissemination of readily usable data products necessitates a streaming processing framework that is both automatable and flexible. Tower networks, such as ICOS, Ameriflux, and NEON, exemplify this issue by requiring large amounts of data to be processed from dispersed measurement sites. Eddy-covariance data from across the NEON network are expected to amount to 100 Gigabytes per day. The complexity of the algorithmic processing necessary to produce high-quality data products together with the continued development of new analysis techniques led to the development of a modular R-package, eddy4R. This allows algorithms provided by NEON and the larger community to be deployed in streaming processing, and to be used by community members alike. In order to control the processing environment, provide a proficient parallel processing structure, and certify dependencies are available during processing, we chose Docker as our "Development and Operations" (DevOps) platform. The Docker framework allows our processing algorithms to be developed, maintained and deployed at scale. Additionally, the eddy4R-Docker framework fosters community use and extensibility via pre-built Docker images and the Github distributed version control system. The capability to process large data sets is reliant upon efficient input and output of data, data compressibility to reduce compute resource loads, and the ability to easily package metadata. The Hierarchical Data Format (HDF5) is a file format that can meet these needs. A NEON standard HDF5 file structure and metadata attributes allow users to explore larger data sets in an intuitive "directory-like" structure adopting the NEON data product naming conventions.

  19. Determination of linear defect depths from eddy currents disturbances

    Science.gov (United States)

    Ramos, Helena Geirinhas; Rocha, Tiago; Pasadas, Dário; Ribeiro, Artur Lopes

    2014-02-01

    One of the still open problems in the inspection research concerns the determination of the maximum depth to which a surface defect goes. Eddy current testing being one of the most sensitive well established inspection methods, able to detect and characterize different type of defects in conductive materials, is an adequate technique to solve this problem. This paper reports a study concerning the disturbances in the magnetic field and in the lines of current due to a machined linear defect having different depths in order to extract relevant information that allows the determination of the defect characteristics. The image of the eddy currents (EC) is paramount to understand the physical phenomena involved. The EC images for this study are generated using a commercial finite element model (FLUX). The excitation used produces a uniform magnetic field on the plate under test in the absence of defects and the disturbances due to the defects are compared with those obtained from experimental measurements. In order to increase the limited penetration depth of the method giant magnetoresistors (GMR) are used to lower the working frequency. The geometry of the excitation planar coil produces a uniform magnetic field on an area of around the GMR sensor, inducing a uniform eddy current distribution on the plate. In the presence of defects in the material surface, the lines of currents inside the material are deviated from their uniform direction and the magnetic field produced by these currents is sensed by the GMR sensor. Besides the theoretical study of the electromagnetic system, the paper describes the experiments that have been carried out to support the theory and conclusions are drawn for cracks having different depths.

  20. Characterization of irradiated fuel rods using pulsed eddy current techniques

    International Nuclear Information System (INIS)

    Martin, M.R.; Francis, W.C.

    1975-11-01

    A number of irradiated fuel rods and unfueled zircaloy cladding tubes (''water tubes'') were obtained from the Saxton reactor through arrangements with the Westinghouse Electric Corporation for use in subsequent irradiation effects and fuel behavior programs. A comprehensive nondestructive and corroborative destructive characterization program was undertaken on these fuel rods and tubes by ANC to provide baseline data on their characteristics prior to further testing and for comparison against post-post data. This report deals primarily with one portion of the NDT program performed remotely in the hot cells. The portion of interest in this paper is the pulsed eddy current inspection used in the nondestructive phase of the work. 6 references

  1. Electromagnetic modeling method for eddy current signal analysis

    International Nuclear Information System (INIS)

    Lee, D. H.; Jung, H. K.; Cheong, Y. M.; Lee, Y. S.; Huh, H.; Yang, D. J.

    2004-10-01

    An electromagnetic modeling method for eddy current signal analysis is necessary before an experiment is performed. Electromagnetic modeling methods consists of the analytical method and the numerical method. Also, the numerical methods can be divided by Finite Element Method(FEM), Boundary Element Method(BEM) and Volume Integral Method(VIM). Each modeling method has some merits and demerits. Therefore, the suitable modeling method can be chosen by considering the characteristics of each modeling. This report explains the principle and application of each modeling method and shows the comparison modeling programs

  2. Large-eddy simulation of swirling pulverized-coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Hu, L.Y.; Luo, Y.H. [Shanghai Jiaotong Univ. (China). School of Mechanical Engineering; Zhou, L.X.; Xu, C.S. [Tsinghua Univ., Beijing (China). Dept. of Engineering Mechanics

    2013-07-01

    A Eulerian-Lagrangian large-eddy simulation (LES) with a Smagorinsky-Lilly sub-grid scale stress model, presumed-PDF fast chemistry and EBU gas combustion models, particle devolatilization and particle combustion models are used to study the turbulence and flame structures of swirling pulverized-coal combustion. The LES statistical results are validated by the measurement results. The instantaneous LES results show that the coherent structures for pulverized coal combustion is stronger than that for swirling gas combustion. The particles are concentrated in the periphery of the coherent structures. The flame is located at the high vorticity and high particle concentration zone.

  3. Eddy current system for inspection of train hollow axles

    Energy Technology Data Exchange (ETDEWEB)

    Chady, Tomasz; Psuj, Grzegorz; Sikora, Ryszard; Kowalczyk, Jacek; Spychalski, Ireneusz [Department of Electrical and Computer Engineering, Faculty of Electrical Engineering, West Pomeranian University of Technology, Szczecin (Poland)

    2014-02-18

    The structural integrity of wheelsets used in rolling stock is of great importance to the safety. In this paper, electromagnetic system with an eddy current transducer suitable for the inspection of hollow axles have been presented. The transducer was developed to detect surface braking defects having depth not smaller than 0.5 mm. Ultrasound technique can be utilized to inspect the whole axle, but it is not sufficiently sensitive to shallow defects located close to the surface. Therefore, the electromagnetic technique is proposed to detect surface breaking cracks that cannot be detected by ultrasonic technique.

  4. Geologic data for borehole ERDA-9, Eddy County, New Mexico

    International Nuclear Information System (INIS)

    Jones, C.L.

    1981-01-01

    Borehole ERDA-9 is an exploratory well drilled in eastern Eddy County, New Mexico to evaluate and test salt beds for disposal of nuclear wastes. The drilling was done between April 28 and June 4, 1976. Lithologic and stratigraphic details of the geologic section in ERDA-9 are described herein. The selection includes: (1) the Mescalero caliche and the Gatuna Formation of Pleistocene age, (2) the Santa Rosa Sandstone of Triassic age, and (3) the Dewey Lake Red Beds, the Rustler Formation, the Salado Formation, and part of the Castile Formation; all of Permian age

  5. Eddy current calculations for the tore supra tokamak

    International Nuclear Information System (INIS)

    Blum, J.; Dupas, L.; Leloup, C.; Thooris, B.

    1983-01-01

    This paper deals with the calculation of the eddy currents in the structures of a Tokamak, which can be assimilated to thin conductors, so that the three-dimensional problem can be reduced mathematically to a two-dimensional one, the variables being two orthogonal coordinates of the considered surface. A variational formulation of the problem in terms of the electric vector potential is then given and a finite element method has been used, which enables to treat the complicated geometry of the toroidal field magnet, the mechanical structures and the vacuum vessels of Tore Supra

  6. Workshops and problems for benchmarking eddy current codes

    International Nuclear Information System (INIS)

    Turner, L.R.; Davey, K.; Ida, N.; Rodger, D.; Kameari, A.; Bossavit, A.; Emson, C.R.I.

    1988-02-01

    A series of six workshops was held to compare eddy current codes, using six benchmark problems. The problems include transient and steady-state ac magnetic fields, close and far boundary conditions, magnetic and non-magnetic materials. All the problems are based either on experiments or on geometries that can be solved analytically. The workshops and solutions to the problems are described. Results show that many different methods and formulations give satisfactory solutions, and that in many cases reduced dimensionality or coarse discretization can give acceptable results while reducing the computer time required. 13 refs., 1 tab

  7. Surface flaw evaluation by vectorized eddy current testing image

    International Nuclear Information System (INIS)

    Endo, Hisashi; Takagi, Toshiyuki

    2006-01-01

    A method of eddy current testing (ECT) data mapping for surface breaking evaluation is studied. The multicoil ECT probe utilized in this paper consists of Transmit-Receive (TR) type sensors as array elements to obtain the information on crack directions. Switching two directional scans, U- and T- modes, gives two-dimensional vector mapping as ECT images. The ECT signals of the TR type sensor also give the information on crack directions from their variation displayed on the complex number plane. Extracting a complex number component of the signals makes it possible to visualize directions of numerically simulated proximate EDM slits. (author)

  8. Large Eddy Simulation of the ventilated wave boundary layer

    DEFF Research Database (Denmark)

    Lohmann, Iris P.; Fredsøe, Jørgen; Sumer, B. Mutlu

    2006-01-01

    A Large Eddy Simulation (LES) of (1) a fully developed turbulent wave boundary layer and (2) case 1 subject to ventilation (i.e., suction and injection varying alternately in phase) has been performed, using the Smagorinsky subgrid-scale model to express the subgrid viscosity. The model was found...... slows down the flow in the full vertical extent of the boundary layer, destabilizes the flow and decreases the mean bed shear stress significantly; whereas suction generally speeds up the flow in the full vertical extent of the boundary layer, stabilizes the flow and increases the mean bed shear stress...

  9. Development of an automatized device for eddy current testing

    International Nuclear Information System (INIS)

    David, B.; Benoist, B.; Champonnois, F.; Viard, J.

    1990-01-01

    To improve performances in eddy current studies, several tools were developed in the Saclay Laboratory: - ELEFANT is a very flexible software which allows a rapid creation of new NDT applications, preserving anytime a full compatibility between computers, applications, data... used under the same ELEFANT controlkey. - Modulo'STA is a modular hardware designed to be the flexible interface between the probe and the computer, driving the measurement, the probe movement... - rotating EC probes with local rotation facilities allow the control of very long steam generator tubes, even bent [fr

  10. Detached Eddy Simulations of an Airfoil in Turbulent Inflow

    DEFF Research Database (Denmark)

    Gilling, Lasse; Sørensen, Niels; Davidson, Lars

    2009-01-01

    The effect of resolving inflow turbulence in detached eddy simulations of airfoil flows is studied. Synthetic turbulence is used for inflow boundary condition. The generated turbulence fields are shown to decay according to experimental data as they are convected through the domain with the free...... stream velocity. The subsonic flow around a NACA 0015 airfoil is studied at Reynolds number 1.6 × 106 and at various angles of attack before and after stall. Simulations with turbulent inflow are compared to experiments and to simulations without turbulent inflow. The results show that the flow...

  11. Subregional characterization of mesoscale eddies across the Brazil-Malvinas Confluence

    Science.gov (United States)

    Mason, Evan; Pascual, Ananda; Gaube, Peter; Ruiz, Simón; Pelegrí, Josep L.; Delepoulle, Antoine

    2017-04-01

    Horizontal and vertical motions associated with coherent mesoscale structures, including eddies and meanders, are responsible for significant global transports of many properties, including heat and mass. Mesoscale vertical fluxes also influence upper ocean biological productivity by mediating the supply of nutrients into the euphotic layer, with potential impacts on the global carbon cycle. The Brazil-Malvinas Confluence (BMC) is a western boundary current region in the South Atlantic with intense mesoscale activity. This region has an active role in the genesis and transformation of water masses and thus is a critical component of the Atlantic meridional overturning circulation. The collision between the Malvinas and Brazil Currents over the Patagonian shelf/slope creates an energetic front that translates offshore to form a vigorous eddy field. Recent improvements in gridded altimetric sea level anomaly fields allow us to track BMC mesoscale eddies with high spatial and temporal resolutions using an automated eddy tracker. We characterize the eddies across fourteen 5° × 5° subregions. Eddy-centric composites of tracers and geostrophic currents diagnosed from a global reanalysis of surface and in situ data reveal substantial subregional heterogeneity. The in situ data are also used to compute the evolving quasi-geostrophic vertical velocity (QG-ω) associated with each instantaneous eddy instance. The QG-ω eddy composites have the expected dipole patterns of alternating upwelling/downwelling, however, the magnitude and sign of azimuthally averaged vertical velocity varies among subregions. Maximum eddy values are found near fronts and sharp topographic gradients. In comparison with regional eddy composites, subregional composites provide refined information about mesoscale eddy heterogeneity.

  12. Passive heat transfer in a turbulent channel flow simulation using large eddy simulation based on the lattice Boltzmann method framework

    Energy Technology Data Exchange (ETDEWEB)

    Wu Hong [National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Beihang University, Beijing 100191 (China); Wang Jiao, E-mail: wangjiao@sjp.buaa.edu.cn [National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Beihang University, Beijing 100191 (China); Tao Zhi [National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Beihang University, Beijing 100191 (China)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer A double MRT-LBM is used to study heat transfer in turbulent channel flow. Black-Right-Pointing-Pointer Turbulent Pr is modeled by dynamic subgrid scale model. Black-Right-Pointing-Pointer Temperature gradients are calculated by the non-equilibrium temperature distribution moments. - Abstract: In this paper, a large eddy simulation based on the lattice Boltzmann framework is carried out to simulate the heat transfer in a turbulent channel flow, in which the temperature can be regarded as a passive scalar. A double multiple relaxation time (DMRT) thermal lattice Boltzmann model is employed. While applying DMRT, a multiple relaxation time D3Q19 model is used to simulate the flow field, and a multiple relaxation time D3Q7 model is used to simulate the temperature field. The dynamic subgrid stress model, in which the turbulent eddy viscosity and the turbulent Prandtl number are dynamically computed, is integrated to describe the subgrid effect. Not only the strain rate but also the temperature gradient is calculated locally by the non-equilibrium moments. The Reynolds number based on the shear velocity and channel half height is 180. The molecular Prandtl numbers are set to be 0.025 and 0.71. Statistical quantities, such as the average velocity, average temperature, Reynolds stress, root mean square (RMS) velocity fluctuations, RMS temperature and turbulent heat flux are obtained and compared with the available data. The results demonstrate great reliability of DMRT-LES in studying turbulence.

  13. Direct and large eddy simulation of turbulent heat transfer at very low Prandtl number: Application to lead–bismuth flows

    International Nuclear Information System (INIS)

    Bricteux, L.; Duponcheel, M.; Winckelmans, G.; Tiselj, I.; Bartosiewicz, Y.

    2012-01-01

    Highlights: ► We perform direct and hybrid-large eddy simulations of high Reynolds and low Prandtl turbulent wall-bounded flows with heat transfer. ► We use a state-of-the-art numerical methods with low energy dissipation and low dispersion. ► We use recent multiscalesubgrid scale models. ► Important results concerning the establishment of near wall modeling strategy in RANS are provided. ► The turbulent Prandtl number that is predicted by our simulation is different than that proposed by some correlations of the literature. - Abstract: This paper deals with the issue of modeling convective turbulent heat transfer of a liquid metal with a Prandtl number down to 0.01, which is the order of magnitude of lead–bismuth eutectic in a liquid metal reactor. This work presents a DNS (direct numerical simulation) and a LES (large eddy simulation) of a channel flow at two different Reynolds numbers, and the results are analyzed in the frame of best practice guidelines for RANS (Reynolds averaged Navier–Stokes) computations used in industrial applications. They primarily show that the turbulent Prandtl number concept should be used with care and that even recent proposed correlations may not be sufficient.

  14. Aerodynamic noise prediction of a Horizontal Axis Wind Turbine using Improved Delayed Detached Eddy Simulation and acoustic analogy

    International Nuclear Information System (INIS)

    Ghasemian, Masoud; Nejat, Amir

    2015-01-01

    Highlights: • The noise predictions are performed by Ffowcs Williams and Hawkings method. • There is a direct relation between the radiated noise and the wind speed. • The tonal peaks in the sound spectra match with the blade passing frequency. • The quadrupole noises have negligible effect on the low frequency noises. - Abstract: This paper presents the results of the aerodynamic and aero-acoustic prediction of the flow field around the National Renewable Energy Laboratory Phase VI wind turbine. The Improved Delayed Detached Eddy Simulation turbulence model is applied to obtain the instantaneous turbulent flow field. The noise prediction is carried out using the Ffowcs Williams and Hawkings acoustic analogy. Simulations are performed for three different inflow conditions, U = 7, 10, 15 m/s. The capability of the Improved Delayed Detached Eddy Simulation turbulence model in massive separation is verified with available experimental data for pressure coefficient. The broadband noises of the turbulent boundary layers and the tonal noises due to the blade passing frequency are predicted via flow field noise simulation. The contribution of the thickness, loading and quadrupole noises are investigated, separately. The results indicated that there is a direct relation between the strength of the radiated noise and the wind speed. Furthermore, the effect of the receiver location on the Overall Sound Pressure Level is investigated

  15. Modelling the dispersion and transport of reactive pollutants in a deep urban street canyon: Using large-eddy simulation

    International Nuclear Information System (INIS)

    Zhong, Jian; Cai, Xiao-Ming; Bloss, William James

    2015-01-01

    This study investigates the dispersion and transport of reactive pollutants in a deep urban street canyon with an aspect ratio of 2 under neutral meteorological conditions using large-eddy simulation. The spatial variation of pollutants is significant due to the existence of two unsteady vortices. The deviation of species abundance from chemical equilibrium for the upper vortex is greater than that for the lower vortex. The interplay of dynamics and chemistry is investigated using two metrics: the photostationary state defect, and the inferred ozone production rate. The latter is found to be negative at all locations within the canyon, pointing to a systematic negative offset to ozone production rates inferred by analogous approaches in environments with incomplete mixing of emissions. This study demonstrates an approach to quantify parameters for a simplified two-box model, which could support traffic management and urban planning strategies and personal exposure assessment. - Highlights: • Large-eddy simulation reproduces two unsteady vortices seen in a lab experiment. • Reactive pollutants in an urban street canyon exhibit significant spatial variation. • O 3 production rate inferred by the NO x -O 3 -steady-state-defect approach is discussed. • Ground level sourced pollutants are largely trapped within the lower vortex. • A method of quantifying parameters of a two-box model is developed. - Reactive pollutants in a deep street canyon exhibit significant spatial variation driven by two unsteady vortices. A method of quantifying parameters of a two-box model is developed

  16. Dispersion of tracers by the oceanic eddy field modelling programme

    International Nuclear Information System (INIS)

    Richards, K.J.; O'Farrell, S.P.

    1987-01-01

    A numerical model has been developed to study the dispersion of tracers by the oceanic eddy field. The present study is designed to study the dispersion of particles in a mesoscale eddy field produced by the numerical model. Dispersion rates are calculated for flows above three types of topography, a flat bottom, a random collection of hills and a ridge. The presence of topography is found to significantly affect the flow. The effective diffusion coefficient of the flow near the bottom is reduced by 20% for the random topography and 60% for the ridge from that for the flat bottom case. Estimates are given of the number of float years required to obtain a given accuracy for the diffusion coefficient. At the surface a modest number of floats (order 5) are required to obtain a 50% accuracy. However at the bottom, to be within a factor of 2 of the true value for the flows considered requires respectively 26, 42 and 103 float years for the flat, random and ridge cases. (author)

  17. Towards an entropy-based detached-eddy simulation

    Science.gov (United States)

    Zhao, Rui; Yan, Chao; Li, XinLiang; Kong, WeiXuan

    2013-10-01

    A concept of entropy increment ratio ( s¯) is introduced for compressible turbulence simulation through a series of direct numerical simulations (DNS). s¯ represents the dissipation rate per unit mechanical energy with the benefit of independence of freestream Mach numbers. Based on this feature, we construct the shielding function f s to describe the boundary layer region and propose an entropy-based detached-eddy simulation method (SDES). This approach follows the spirit of delayed detached-eddy simulation (DDES) proposed by Spalart et al. in 2005, but it exhibits much better behavior after their performances are compared in the following flows, namely, pure attached flow with thick boundary layer (a supersonic flat-plate flow with high Reynolds number), fully separated flow (the supersonic base flow), and separated-reattached flow (the supersonic cavity-ramp flow). The Reynolds-averaged Navier-Stokes (RANS) resolved region is reliably preserved and the modeled stress depletion (MSD) phenomenon which is inherent in DES and DDES is partly alleviated. Moreover, this new hybrid strategy is simple and general, making it applicable to other models related to the boundary layer predictions.

  18. Preliminary Investigations of Eddy Current Effects on a Spinning Disk

    International Nuclear Information System (INIS)

    Piggott, W T; Walston, S; Mayhall, D

    2006-01-01

    The design of the positron source target for the International Linear Collider (ILC) envisions a Ti6Al4V wheel rotating in a large magnetic field (5-10 Tesla) being impacted by a photon beam to produce positrons. One of the many challenges for this system is determining how large a motor will be needed to spin the shaft. The wheel spinning in the magnetic field induces an eddy current in the wheel, which retards the spinning motion of the wheel. Earlier calculations by Mayhall [1] have shown that those eddy forces could be quite large, and resulted in the preliminary design being moved from a solid disk to a rim and spoke design, as shown in Figure 1. A series of experiments with a spinning metal disk were run at the Stanford Linear Accelerator Center (SLAC) to provide experimental validation of the Maxwell 3D simulations. This report will give a brief outline of the experimental setup and results. In addition, earlier work by Smythe [2] will be used to compare with the experimental results

  19. Vacuum chamber eddy current correction coil for the AGS Booster

    International Nuclear Information System (INIS)

    Danby, G.; Jackson, J.

    1988-01-01

    The AGS Booster injector will perform a variety of functions. Heavy ion acceleration requires a bakeable, ultra-high vacuum system (VC). Acceleration for intense proton beams requires rapid cycling (B /preceq/ 10T/sec). If straight forward heavy walled VC are used, the field perturbations due to eddy currents are large. The state of the art lattice has highly distributed lumped sextupoles capable of substantially correcting the induced field nonlinearity. Nevertheless, for the very highest space charge-intensity limits, it is desirable to have the capability to remove eddy current fields at the source. Correction coils attached to the outside of the VC cancel its current aberrations over the required good field aperture. These can be passively powered by transformer action, using two turn windings around the magnet yoke. Programmed power supplies can also be used. This inexpensive additional correction option uses a three turn per quadrant coil which follows the local contour of the VC. Transverse movements of several mms of the VC will have no beam optical effect since the large field aberrations and their corrections have the same displaced coordinates. Experimental and computer studies will be presented, as well as mechanical and electrical design of a simple method of construction. 6 figs

  20. Vacuum chamber eddy current correction coil for the AGS booster

    International Nuclear Information System (INIS)

    Danby, G.; Jackson, J.

    1988-01-01

    This paper reports on the AGS Booster injector that performs a variety of functions. Heavy ion acceleration requires a bakeable, ultra-high vacuum system (VC). Acceleration for intense proton beams requires rapid cycling (B ≤10T/sec). If straight forward heavy walled VC are used, the field perturbations due to eddy currents are large. The state of the art lattice has highly distributed lumped sextupoles capable of substantially correcting the induced field nonlinearity. Nevertheless, for the very highest space charge-intensity limits, it is desirable to have the capability to remove eddy current fields at the source. Correction coils attached to the outside of the VC cancel its current aberrations over the required good field aperture. These can be passively powered by transformer action, using two turn windings around the magnet yoke. Programmed power supplies can also be used. This inexpensive additional correction option uses a three turn per quadrant coil which follows the local contour of the VC. Transverse movements of several mms of the VC will have no beam optical effect since the large field aberrations and their corrections have the same displace coordinates. Experimental and computer studies will be presented, as well as mechanical and electrical design of a simple method of construction

  1. Transient eddy feedback and low-frequency variability

    International Nuclear Information System (INIS)

    Robinson, W.A.

    1994-01-01

    Superposed on any externally driven secular climatic change are fluctuations that arise from the internal nonlinear dynamics of the climate system. These internally generated variations may involve interactions between the atmosphere and the ocean, as in the case of El Nino, or they may arise from the dynamics of the atmosphere alone. Here we discuss the dynamics of interactions between transient eddies and lower-frequency motions in the atmosphere. The interactions between more transient and more persistent motions can be divided into two types. Nonlinear interactions among the transient motions can act as an essentially random source of low-frequency motion. The idea that the low-frequencies respond in a linear way to stochastic forcing from higher frequencies has been applied to the generation of planetary waves and to the forcing of changes in global angular momentum. In addition to stochastic coupling, there are systematic interactions, denoted feedbacks, through which the persistent motions modulate their own forcing by the transient eddies. This paper discusses the dynamics of these feedbacks

  2. Eddy current techniques for super duplex stainless steel characterization

    Science.gov (United States)

    Camerini, C.; Sacramento, R.; Areiza, M. C.; Rocha, A.; Santos, R.; Rebello, J. M.; Pereira, G.

    2015-08-01

    Super duplex stainless steel (SDSS) is a two-phase material where the microstructure consists of grains of ferrite (δ) and austenite (γ). SDSS exhibit an attractive combination of properties, such as: strength, toughness and stress corrosion cracking resistance. Nevertheless, SDSS attain these properties after a controlled solution heat treatment, leading to a similar volumetric fraction of δ and γ. Any further heat treatment, welding operation for example, can change the balance of the original phases, or may also lead to precipitation of a deleterious phase, such as sigma (σ). For these situations, the material corrosion resistance is severely impaired. In the present study, several SDSS samples with low σ phase content and non-balanced microstructure were intentionally obtained by thermally treating SDSS specimens. Electromagnetic techniques, conventional Eddy Current Testing (ECT) and Saturated Low Frequency Eddy Current (SLOFEC), were employed to characterize the SDSS samples. The results showed that ECT and SLOFEC are reliable techniques to evaluate σ phase presence in SDSS and can provide an estimation of the δ content.

  3. Eddy Current Thermography: System Development and Its Application in NDT

    International Nuclear Information System (INIS)

    Nurliyana Shamimie Rusli; Ilham Mukriz Zainal Abidin; Sidek, H.A.A.

    2015-01-01

    Eddy Current Thermography (ECT) is an integrative technique which combines eddy current and thermographic NDT in order to provide an efficient method for defect detection. The technique is applicable to electrically conductive material and has the ability to detect surface and subsurface defect. ECT is a non-contact technique; has the ability to provide instantaneous response and high scanning speed that makes it reliable for defect detection and assessment. The technique combines electromagnetic excitation of the work-piece via a coil carrying current, heating of the material by induction and inspection by transient infrared thermography. In this paper, the development of ECT system is detailed, including coil design for global and local heating of samples, and optimisation of excitation parameters (frequency, power, heating duration etc). Results from 3D FEM simulation and experimental investigations are also presented to provide the overview of underlying phenomena and application of ECT. The work demonstrates the effectiveness of the developed ECT system and technique in defect detection and assessment. (author)

  4. Modeling and analysis of a novel planar eddy current damper

    Science.gov (United States)

    Zhang, He; Kou, Baoquan; Jin, Yinxi; Zhang, Lu; Zhang, Hailin; Li, Liyi

    2014-05-01

    In this paper, a novel 2-DOF permanent magnet planar eddy current damper is proposed, of which the stator is made of a copper plate and the mover is composed of two orthogonal 1-D permanent magnet arrays with a double sided structure. The main objective of the planar eddy current damper is to provide two orthogonal damping forces for dynamic systems like the 2-DOF high precision positioning system. Firstly, the basic structure and the operating principle of the planar damper are introduced. Secondly, the analytical model of the planar damper is established where the magnetic flux density distribution of the permanent magnet arrays is obtained by using the equivalent magnetic charge method and the image method. Then, the analytical expressions of the damping force and damping coefficient are derived. Lastly, to verify the analytical model, the finite element method (FEM) is adopted for calculating the flux density and a planar damper prototype is manufactured and thoroughly tested. The results from FEM and experiments are in good agreement with the ones from the analytical expressions indicating that the analytical model is reasonable and correct.

  5. Evidence of a southward eddy corridor in the South-West Indian ocean

    CSIR Research Space (South Africa)

    Ansorge, IJ

    2015-09-01

    Full Text Available Mesoscale eddies and meanders have been shown to be one of the dominant sources of flow variability in the world s ocean. One example of an isolated eddy hotspot is the South-West Indian Ridge (SWIR). Several investigations have shown that the SWIR...

  6. Realizability conditions for the turbulent stress tensor in large-eddy simulation

    NARCIS (Netherlands)

    Vreman, A.W.; Geurts, Bernardus J.; Kuerten, Johannes G.M.

    1994-01-01

    The turbulent stress tensor in large-eddy simulation is examined from a theoretical point of view. Realizability conditions for the components of this tensor are derived, which hold if and only if the filter function is positive. The spectral cut-off, one of the filters frequently used in large-eddy

  7. An instrument to measure turbulent eddy fluxes in the atmosphere of Mars

    Science.gov (United States)

    S. Rafkin; D. Banfield; R. Dissly; J. Silver; A. Stanton; E. Wilkinson; W. Massman; J. Ham

    2012-01-01

    Turbulent eddies in the planetary boundary layer of the terrestrial planet atmospheres are the primary mechanism by which energy, momentum, gasses, and aerosols are exchanged between the surface and the atmosphere [1]. The importance of eddies has long been recognized by the Earth atmospheric science community, and turbulent theory for Earth has a long history with a...

  8. Eddy-mediated biological productivity in the Bay of Bengal during fall and spring intermonsoons

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Nuncio, M.; Ramaiah, N; Sardesai, S.; Narvekar, J.; Fernandes, V.; Paul, J.T.

    -pumping, thereby cooling the water to a greater extent. However, the cyclonic eddies were unable to break the stratification of the top 20m layer, thereby curtailing their effects below this depth during both seasons. Eddy-pumping not only cooled the water column...

  9. Energy and generating mechanism of a subsurface, cold core eddy in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Babu, M.T.; Rao, D.P.

    Computation of available potential energy (APE) of a recently observed cold core, subsurface eddy (centered at 17 degrees 40'N and 85 degrees 19'E) in the Bay of Bengal revealed that the energy maxima associated with the eddy was of the order of 1...

  10. Large-eddy simulation of the temporal mixing layer using the Clark model

    NARCIS (Netherlands)

    Vreman, A.W.; Geurts, B.J.; Kuerten, J.G.M.

    1996-01-01

    The Clark model for the turbulent stress tensor in large-eddy simulation is investigated from a theoretical and computational point of view. In order to be applicable to compressible turbulent flows, the Clark model has been reformulated. Actual large-eddy simulation of a weakly compressible,

  11. Short Communication Effects of deep-sea eddies on the northern ...

    African Journals Online (AJOL)

    A satellite-tracked drifter and complementary altimetry data confirmed the dimensions of the eddy and tracked its movement towards the coast. Shelf-edge upwelling was measured at NMR by an underwater temperature recorder (UTR) when the cyclonic eddy first came into contact with the shelf and again when the cyclonic ...

  12. Hydrologic and radiative feedbacks on extratropical transient eddies: Implications of global warming

    International Nuclear Information System (INIS)

    Gutowski, W.J. Jr.; Branscome, L.E.

    1994-01-01

    Atmospheric transient eddies contribute significantly to global energy and water cycles through their transports of sensible heat and water vapor. Changes in global climate induced by greenhouse enhancement will likely alter transient eddy behavior. General circulation models (GCMs) can simulate such alterations, but unraveling all the feedbacks that occur in GCMs is difficult

  13. Eddy current heating of irregularly shaped plates by slow ramped fields

    International Nuclear Information System (INIS)

    Dresner, L.

    1979-01-01

    Theorems are presented for estimating eddy current heating of irregularly shaped plates by a perpendicular ramped field. The theorems, which are derived from two complementary variational principles, give upper and lower bounds to the eddy current heating. Illustrative results are given for rectangles, isosceles triangles, sectors of circular annuli, rhombuses, and L-shaped plates. A comparison is made with earlier work

  14. Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications

    Directory of Open Access Journals (Sweden)

    Damhuji Rifai

    2016-02-01

    Full Text Available Non-destructive eddy current testing (ECT is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper.

  15. Eddy current testing. Evaluation of cracks propagation in austenitic steel cladding

    International Nuclear Information System (INIS)

    Pigeon, M.

    1983-12-01

    A low frequency eddy current method has been developed to evaluate the ligament between crack front and cladding surface and measure crack length. It uses a large surface probe to obtain a low sensitivity on surface variations and a good penetration of eddy current

  16. Evolution of physical and biological characteristics of mesoscale eddy in north-central Red Sea

    KAUST Repository

    Zarokanellos, Nikolaos; Jones, Burton

    2015-01-01

    -central Red Sea (NCRS) where anticyclonic eddies have been observed. The study began with a ship-based characterization of the eddy and was followed by a three-month observational time series using an autonomous glider equipped with a CTD, oxygen sensor

  17. Numerical and experimental analysis of eddy currents induced in tokamak machines

    International Nuclear Information System (INIS)

    Takahashi, T.; Takahashi, G.; Kazawa, Y.; Suzuki, Y.

    1977-01-01

    This paper deals with eddy current phenomena in Tokamak machines. A numerical method is presented which will permit eddy currents to be calculated. Examples of numerical results and a discussion of the JT-60 are shown. Calculations are checked by measurements in basic models

  18. Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications

    Science.gov (United States)

    Rifai, Damhuji; Abdalla, Ahmed N.; Ali, Kharudin; Razali, Ramdan

    2016-01-01

    Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper. PMID:26927123

  19. Impact of Preferred Eddy Tracks on Transport and Mixing in the Eastern South Pacific

    Science.gov (United States)

    Belmadani, A.; Donoso, D.; Auger, P. A.; Chaigneau, A.

    2017-12-01

    Mesoscale eddies, which play a fundamental role in the transport of mass, heat, nutrients, and biota across the oceans, have been suggested to propagate preferently along specific tracks. These preferred pathways, also called eddy trains, are near-zonal due to westward drift of individual vortices, and tend to be polarized (ie alternatively dominated by anticyclonic/cyclonic eddies), coinciding with the recently discovered latent striations (quasi-zonal mesoscale jet-like features). While significant effort has been made to understand the dynamics of striations and their interplay with mesoscale eddies, the impact of repeated eddy tracks on physical (temperature, salinity), biogeochemical (oxygen, carbon, nutrients) and other tracers (e.g. chlorophyll, marine debris) has received little attention. Here we report on the results of numerical modeling experiments that simulate the impact of preferred eddy tracks on the transport and mixing of water particles in the Eastern South Pacific off Chile. A 30-year interannual simulation of the oceanic circulation in this region has been performed over 1984-2013 with the ROMS (Regional Oceanic Modeling System) at an eddy-resolving resolution (10 km). Objective tracking of mesoscale coherent vortices is obtained using automated methods, allowing to compute the contribution of eddies to the ocean circulation. Preferred eddy tracks are further isolated from the more random eddies, by comparing the distances between individual tracks and the striated pattern in long-term mean eddy polarity with a least-squares approach. The remaining non-eddying flow may also be decomposed into time-mean and anomalous circulation, and/or small- and large-scale circulation. Neutrally-buoyant Lagrangian floats are then released uniformly into the various flow components as well as the total flow, and tracked forward in time with the ARIANE software. The dispersion patterns of water particles are used to estimate the respective contributions of

  20. Evolution of physical and biological characteristics of mesoscale eddy in north-central Red Sea

    KAUST Repository

    Zarokanellos, Nikolaos

    2015-04-01

    Eddies appear to be important to both the physical and biogeochemical dynamics of the Red Sea. Numerical simulations of physical dynamics and remote sensing studies of chlorophyll concentration and sea surface height in the Red Sea indicate their importance to the upper portions of the sea (Raitsos et al., 2013; Yao et al., 2014; Zhan et al., 2014). Despite their apparent importance, process studies of these eddies have been lacking. In March 2013 we began an extended observational study of the north-central Red Sea (NCRS) where anticyclonic eddies have been observed. The study began with a ship-based characterization of the eddy and was followed by a three-month observational time series using an autonomous glider equipped with a CTD, oxygen sensor, and optical sensors for chlorophyll, CDOM and optical backscatter. The ship-based study captured an initial snapshot of an anticyclonic eddy and it\\'s associated biological and bio-optical distributions. Initially, chlorophyll distributions tended to mirror the density distribution, with deeper isopycnals and chlorophyll maximum depth in the anticyclonic eddy center. The anticyclone eddy in March had an along basin diameter of 150 km, penetrated vertically less than 150 m and elevated near surface chlorophyll concentrations appeared along its outer boundary. The shallowing of the pycnocline of the outer boundaries of the anticyclone eddy on March may elevate nutrients into the lower euphotic zone, contributing to phytoplankton productivity and biomass within the eddy. This eddy contains most of the kinetic energy of the region with the maximum velocities up to 30 - 35 cm/s. The eddy appeared to interact with the coastal reefs where exchange particulate and dissolved matter may occur. The autonomous glider provided the spring-to-summer progression of the system with increasing stratification, shallowing of the subsurface chlorophyll maximum, and fluctuations in the position and intensity of the eddy. Our glider effort

  1. Difference between highlight and object colors enhances glossiness.

    Science.gov (United States)

    Hanada, Mitsuhiko

    2012-06-01

    The effect of highlight and object colors on perception of glossiness was examined. Ten participants rated glossiness of object images. The color coordinates of objects and highlights were varied while luminance of each pixel was unchanged. Four colors were used for objects and highlights. Objects were perceived as glossier when the highlight color was different from the object color than when they were the same. Objects with some unnatural combinations of highlight and object colors were perceived to be as glossy as those with natural color combinations. The results suggested that differences between highlight and object colors enhance perceived glossiness and that perceived glossiness does not depend on naturalness of color combination for highlights and objects.

  2. Dissipative inertial transport patterns near coherent Lagrangian eddies in the ocean.

    Science.gov (United States)

    Beron-Vera, Francisco J; Olascoaga, María J; Haller, George; Farazmand, Mohammad; Triñanes, Joaquín; Wang, Yan

    2015-08-01

    Recent developments in dynamical systems theory have revealed long-lived and coherent Lagrangian (i.e., material) eddies in incompressible, satellite-derived surface ocean velocity fields. Paradoxically, observed drifting buoys and floating matter tend to create dissipative-looking patterns near oceanic eddies, which appear to be inconsistent with the conservative fluid particle patterns created by coherent Lagrangian eddies. Here, we show that inclusion of inertial effects (i.e., those produced by the buoyancy and size finiteness of an object) in a rotating two-dimensional incompressible flow context resolves this paradox. Specifically, we obtain that anticyclonic coherent Lagrangian eddies attract (repel) negatively (positively) buoyant finite-size particles, while cyclonic coherent Lagrangian eddies attract (repel) positively (negatively) buoyant finite-size particles. We show how these results explain dissipative-looking satellite-tracked surface drifter and subsurface float trajectories, as well as satellite-derived Sargassum distributions.

  3. Automation of eddy current system for in-service inspection of turbine and generator rotor bores

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    The current project (EPRI-RP-1975-5) is a continuation of activities that began several years ago. Those results (EPRI-RP-1957-1) indicated that eddy current testing shows promise for in-service inspection. The current project investigates the degree to which eddy current testing can be used to replace bore magnetic particle testing. For this purpose, correlation studies between eddy current and magnetic particle tests are being undertaken on laboratory rotor sections and field test pieces of rotors. The eddy current data are to be gathered automatically by a combination of the Nortec-25L Eddyscope (to provide the analog eddy current signals) and the General Electric DATAQ/sup TM/ (a registered trademark of the General Electric Co.) System (to perform the automatic data acquisition). This paper describes some test results on a flaked laboratory rotor section

  4. Estimation of turbulence dissipation rate by Large eddy PIV method in an agitated vessel

    Directory of Open Access Journals (Sweden)

    Kysela Bohuš

    2015-01-01

    Full Text Available The distribution of turbulent kinetic energy dissipation rate is important for design of mixing apparatuses in chemical industry. Generally used experimental methods of velocity measurements for measurement in complex geometries of an agitated vessel disallow measurement in resolution of small scales close to turbulence dissipation ones. Therefore, Particle image velocity (PIV measurement method improved by large eddy Ply approach was used. Large eddy PIV method is based on modeling of smallest eddies by a sub grid scale (SGS model. This method is similar to numerical calculations using Large Eddy Simulation (LES and the same SGS models are used. In this work the basic Smagorinsky model was employed and compared with power law approximation. Time resolved PIV data were processed by Large Eddy PIV approach and the obtained results of turbulent kinetic dissipation rate were compared in selected points for several operating conditions (impeller speed, operating liquid viscosity.

  5. Benchmarking the mesoscale variability in global ocean eddy-permitting numerical systems

    Science.gov (United States)

    Cipollone, Andrea; Masina, Simona; Storto, Andrea; Iovino, Doroteaciro

    2017-10-01

    The role of data assimilation procedures on representing ocean mesoscale variability is assessed by applying eddy statistics to a state-of-the-art global ocean reanalysis (C-GLORS), a free global ocean simulation (performed with the NEMO system) and an observation-based dataset (ARMOR3D) used as an independent benchmark. Numerical results are computed on a 1/4 ∘ horizontal grid (ORCA025) and share the same resolution with ARMOR3D dataset. This "eddy-permitting" resolution is sufficient to allow ocean eddies to form. Further to assessing the eddy statistics from three different datasets, a global three-dimensional eddy detection system is implemented in order to bypass the need of regional-dependent definition of thresholds, typical of commonly adopted eddy detection algorithms. It thus provides full three-dimensional eddy statistics segmenting vertical profiles from local rotational velocities. This criterion is crucial for discerning real eddies from transient surface noise that inevitably affects any two-dimensional algorithm. Data assimilation enhances and corrects mesoscale variability on a wide range of features that cannot be well reproduced otherwise. The free simulation fairly reproduces eddies emerging from western boundary currents and deep baroclinic instabilities, while underestimates shallower vortexes that populate the full basin. The ocean reanalysis recovers most of the missing turbulence, shown by satellite products , that is not generated by the model itself and consistently projects surface variability deep into the water column. The comparison with the statistically reconstructed vertical profiles from ARMOR3D show that ocean data assimilation is able to embed variability into the model dynamics, constraining eddies with in situ and altimetry observation and generating them consistently with local environment.

  6. Inference and Biogeochemical Response of Vertical Velocities inside a Mode Water Eddy

    Science.gov (United States)

    Barceló-Llull, B.; Pallas Sanz, E.; Sangrà, P.

    2016-02-01

    With the aim to study the modulation of the biogeochemical fluxes by the ageostrophic secondary circulation in anticyclonic mesoscale eddies, a typical eddy of the Canary Eddy Corridor was interdisciplinary surveyed on September 2014 in the framework of the PUMP project. The eddy was elliptical shaped, 4 month old, 110 km diameter and 400 m depth. It was an intrathermocline type often also referred as mode water eddy type. We inferred the mesoscale vertical velocity field resolving a generalized omega equation from the 3D density and ADCP velocity fields of a five-day sampled CTD-SeaSoar regular grid centred on the eddy. The grid transects where 10 nautical miles apart. Although complex, in average, the inferred omega velocity field (hereafter w) shows a dipolar structure with downwelling velocities upstream of the propagation path (west) and upwelling velocities downstream. The w at the eddy center was zero and maximum values were located at the periphery attaining ca. 6 m day-1. Coinciding with the occurrence of the vertical velocities cells a noticeable enhancement of phytoplankton biomass was observed at the eddy periphery respect to the far field. A corresponding upward diapycnal flux of nutrients was also observed at the periphery. As minimum velocities where reached at the eddy center, lineal Ekman pumping mechanism was discarded. Minimum values of phytoplankton biomass where also observed at the eddy center. The possible mechanisms for such dipolar w cell are still being investigated, but an analysis of the generalized omega equation forcing terms suggest that it may be a combination of horizontal deformation and advection of vorticity by the ageostrophic current (related to nonlinear Ekman pumping). As expected for Trades, the wind was rather constant and uniform with a speed of ca. 5 m s-1. Diagnosed nonlinear Ekman pumping leaded also to a dipolar cell that mirrors the omega w dipolar cell.

  7. Sound-speed structure and propagational characteristics of a cold core eddy in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Babu, M.T.; Murty, T.V.R.

    reduces by about 20 m across the eddy. Simulation studies showed that the rays passing through the eddy undergoes a reduction in the path length thereby reducing the travel time. Travel time delay causEd. by the eddy is of the order of 200 milliseconds...

  8. USE OF RELAXED EDDY ACCUMULATION TO MEASURE BIOSPHERE-ATMOSPHERE EXCHANGE OF ISOPRENE AND OTHER BIOLOGICAL TRACE GASES

    Science.gov (United States)

    The micrometeorological flux measurement technique known as relaxed eddy accumulation (REA) holds promise as a powerful new tool for ecologists. The more popular eddy covariance (eddy correlation) technique requires the use of sensors that can respond at fast rates (10 Hz), and t...

  9. Impacts of northern Tibetan Plateau on East Asian summer rainfall via modulating midlatitude transient eddies

    Science.gov (United States)

    Deng, Jiechun; Xu, Haiming; Shi, Ning; Zhang, Leying; Ma, Jing

    2017-08-01

    Roles of the Tibetan Plateau (TP) in forming and changing the seasonal Asian climate system have been widely explored. However, little is known about modulation effects of the TP on extratropical transient eddies (TEs) and subsequent synoptic responses of the East Asian rainfall. In this study, the Community Atmosphere Model version 5.1 coupled with a slab ocean model is employed to highlight the important role of the TP in regulating the upper-tropospheric transient wave train. Comparison between sensitivity experiments with and without the TP shows that the northern TP excites a strong anomalous anticyclone, which shifts the upper-level East Asian westerly jet northward and helps transfer barotropic and baroclinic energy from the mean flow to the synoptic TE flow. The transient wave train is primarily shifted northward by northern TP and is forced to propagate southeastward along the eastern flank of the TP until reaching eastern China. Before the strengthening of monsoonal southerlies, the TP-modulated transient wave train cools the troposphere, which decreases the static stability over northern China. Meanwhile, the associated anomalous warm advection induces ascending motion, leading to excessive rainfall by releasing unstable energy as the southerly strengthens. Due to the southeastward propagation of the wave train, anomalous heavy rainfall subsequently appears over eastern China from north to south, which increases day-to-day rainfall variation in this region. Additionally, occurrence of this upper-tropospheric transient wave train associated with low-level southerly peak is substantially increased by northern TP.

  10. Corrosion Assessment of Steel Bars Used in Reinforced Concrete Structures by Means of Eddy Current Testing

    Science.gov (United States)

    de Alcantara, Naasson P.; da Silva, Felipe M.; Guimarães, Mateus T.; Pereira, Matheus D.

    2015-01-01

    This paper presents a theoretical and experimental study on the use of Eddy Current Testing (ECT) to evaluate corrosion processes in steel bars used in reinforced concrete structures. The paper presents the mathematical basis of the ECT sensor built by the authors; followed by a finite element analysis. The results obtained in the simulations are compared with those obtained in experimental tests performed by the authors. Effective resistances and inductances; voltage drops and phase angles of wound coil are calculated using both; simulated and experimental data; and demonstrate a strong correlation. The production of samples of corroded steel bars; by using an impressed current technique is also presented. The authors performed experimental tests in the laboratory using handmade sensors; and the corroded samples. In the tests four gauges; with five levels of loss-of-mass references for each one were used. The results are analyzed in the light of the loss-of-mass and show a strong linear behavior for the analyzed parameters. The conclusions emphasize the feasibility of the proposed technique and highlight opportunities for future works. PMID:26712754

  11. Large eddy simulation of Loss of Vacuum Accident in STARDUST facility

    International Nuclear Information System (INIS)

    Benedetti, Miriam; Gaudio, Pasquale; Lupelli, Ivan; Malizia, Andrea; Porfiri, Maria Teresa; Richetta, Maria

    2013-01-01

    Highlights: ► Fusion safety, plasma material interaction. ► Numerical and experimental data comparison to analyze the consequences of Loss of Vacuum Accident that can provoke dust mobilization inside the Vacuum Vessel of the Nuclear Fusion Reactor ITER-like. -- Abstract: The development of computational fluid dynamic (CFD) models of air ingress into the vacuum vessel (VV) represents an important issue concerning the safety analysis of nuclear fusion devices, in particular in the field of dust mobilization. The present work deals with the large eddy simulations (LES) of fluid dynamic fields during a vessel filling at near vacuum conditions to support the safety study of Loss of Vacuum Accidents (LOVA) events triggered by air income. The model's results are compared to the experimental data provided by STARDUST facility at different pressurization rates (100 Pa/s, 300 Pa/s and 500 Pa/s). Simulation's results compare favorably with experimental data, demonstrating the possibility of implementing LES in large vacuum systems as tokamaks

  12. Corrosion Assessment of Steel Bars Used in Reinforced Concrete Structures by Means of Eddy Current Testing

    Directory of Open Access Journals (Sweden)

    Naasson P. de Alcantara

    2015-12-01

    Full Text Available This paper presents a theoretical and experimental study on the use of Eddy Current Testing (ECT to evaluate corrosion processes in steel bars used in reinforced concrete structures. The paper presents the mathematical basis of the ECT sensor built by the authors; followed by a finite element analysis. The results obtained in the simulations are compared with those obtained in experimental tests performed by the authors. Effective resistances and inductances; voltage drops and phase angles of wound coil are calculated using both; simulated and experimental data; and demonstrate a strong correlation. The production of samples of corroded steel bars; by using an impressed current technique is also presented. The authors performed experimental tests in the laboratory using handmade sensors; and the corroded samples. In the tests four gauges; with five levels of loss-of-mass references for each one were used. The results are analyzed in the light of the loss-of-mass and show a strong linear behavior for the analyzed parameters. The conclusions emphasize the feasibility of the proposed technique and highlight opportunities for future works.

  13. Role of mesoscale eddies in the global ocean uptake of anthropogenic CO2

    International Nuclear Information System (INIS)

    Zouhair, Lachkar

    2007-02-01

    Mesoscale eddies play a fundamental role in ocean dynamics particularly in the Southern Ocean. Global-scale tracer simulations are typically made at coarse resolution without explicitly modeling eddies. Here we ask what role do eddies play in ocean uptake, storage, and meridional transport of anthropogenic CO 2 , CFC-11 and bomb Δ 14 C. We made global anthropogenic transient tracer simulations in coarse-resolution, ORCA2, and eddy-permitting, ORCA05 and ORCA025, versions of the ocean modelling system NEMO. We focus on the Southern Ocean where tracer air-sea fluxes are largest. Eddies have little effect on bomb Δ 14 C uptake and storage. Yet for CFC-11 and anthropogenic CO 2 , increased eddy activity reduces southern extra-tropical uptake by 28% and 25% respectively, thereby providing better agreement with observations. It is shown that the discrepancies in the equilibration times between the three tracers determine their respective sensitivities to the model horizontal resolution. Applying Gent and McWilliams (1990) (GM) parameterization of eddies in the non-eddying version of the model does improve results, but not enough. An in-depth investigation of the mechanisms by which eddies affect the uptake of the transient tracers shows that including mesoscale eddies leads to an overall reduction in the Antarctic Intermediate Water (AAIW) ventilation, and modifies substantially the spatial distribution of their source regions. This investigation reveals also that the GM parameterization still overestimates the ventilation and the subduction of AAIW in the Indian Ocean where the simulated mixed layer is particularly deep during the winter. This work suggests that most current coarse-resolution models may overestimate the ventilation of AAIW in the Indian sector of the Southern Ocean. This study shows also that the use of the GM parameterization may be of limited utility where mixed layer is relatively deep and confirms the general need for a more adequate

  14. Brookhaven highlights, October 1, 1989--September 30, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Rowe, M.S.; Cohen, A.; Greenberg, D.; Seubert, L.; Kuper, J.B.H. (eds.)

    1990-01-01

    This report discusses research being conducted at Brookhaven National Laboratory. Highlights from all the department are illustrated. The main topics are on accelerator development and applications. (LSP)

  15. Remote field eddy current testing for steam generator inspection of fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Noriyasu, E-mail: noriyasu.kobayashi@toshiba.co.jp [Power and Industrial Systems Research and Development Center, Toshiba Corporation, 8, Shinsugita-cho, Isogo-ku, Yokohama 235-8523 (Japan); Ueno, Souichi; Nagai, Satoshi; Ochiai, Makoto [Power and Industrial Systems Research and Development Center, Toshiba Corporation, 8, Shinsugita-cho, Isogo-ku, Yokohama 235-8523 (Japan); Jimbo, Noboru [Isogo Nuclear Engineering Center, Toshiba Corporation, 8, Shinsugita-cho, Isogo-ku, Yokohama 235-8523 (Japan)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer We confirmed defect detection performances of remote field eddy current testing. Black-Right-Pointing-Pointer It is difficult to inspect outer surface of double wall tube steam generator. Black-Right-Pointing-Pointer We used coils with flux guide made of iron-nickel alloy for high sensitivity. Black-Right-Pointing-Pointer Output voltage of detector coil increased more than 100 times. Black-Right-Pointing-Pointer We were able to detect small hole defect of 1mm in diameter on outer surface. - Abstract: We confirmed the defect detection performances of the remote field eddy current testing (RFECT) in order to inspect the helical-coil-type double wall tube steam generator (DWTSG) with the wire mesh layer for the new small fast reactor 4S (Super-Safe, Small and Simple). As the high sensitivity techniques, we tried to increase the direct magnetic field intensity in the vicinity of the inner wall of the tube and decrease the direct magnetic field around the central axis of the tube using the exciter coil with the flux guide made of the iron-nickel alloy. We adopted the horizontal type multiple detector coils with the flux guides arrayed circumferentially to enhance the sensitivity of the radial component. According to the experimental results, the output voltage of the detector coil in the region of indirect magnetic field increased more than 100 times by the application of the exciter and detector coils with the flux guides. Finally, we were able to detect the small hole defect of 1 mm in diameter and 20% of the outer tube thickness in depth over the wire mesh layer by the adoption of the exciter coil and horizontal type multiple detector coils with the flux guides. We also confirmed that the RFECT probe is useful for detecting thinning defects. These experimental results indicated that there is the possibility that we can inspect the double wall tube with the wire mesh layer using the RFECT.

  16. Large Eddy Simulation and the effect of the turbulent inlet conditions in the mixing Tee

    International Nuclear Information System (INIS)

    Ndombo, Jean-Marc; Howard, Richard J.A.

    2011-01-01

    Highlights: → LES of Tee junctions can easily reproduce the bulk flow. → The presence or absence of a turbulent inlet condition has an affect on the wall heat transfer. → The maximum heat transfer moves 1 cm and reduces by 10% when a turbulent inlet is used. - Abstract: Thermal fatigue in Pressurized Water Reactor plants has been found to be very acute in some hot/cold Tee junction mixing zones. Large Eddy Simulation (LES) can be used to capture the unsteadiness which is responsible for the large mechanical stresses associated with thermal fatigue. Here one LES subgrid model is studied, namely the Dynamic Smagorinsky model. This paper has two goals. The first is to demonstrate some results obtained using the EDF R and D Code Saturne applied to the Vattenfall Tee junction benchmark (version 2006) and the second is to look at the effect of including synthetic turbulence at the Tee junction pipe inlets. The last goal is the main topic of this paper. The Synthetic Eddy Method is used to create the turbulent inlet conditions and is applied to two kinds of grids. One contains six million cells and the other ten million. The addition of turbulence at the inlet does not seem to have much effect on the bulk flow and all computations are in good agreement with the experimental data. However, the inlet turbulence does have an effect on the near wall flow. All cases show that the wall temperature fluctuation and the wall temperature/velocity correlation are not the same when a turbulent inlet condition is used. Inclusion of the turbulent inlet condition moves the downstream location of the maximum temperature/velocity correlation by 1 cm and reduces its magnitude by 10%. This result is very important because the temperature/velocity correlation is closely related to the turbulent heat transfer in the flow, which is in turn responsible for the mechanical stresses on the structure. Finally we have studied in detail the influence of the turbulent inlet condition just

  17. Advectional enhancement of eddy diffusivity under parametric disorder

    International Nuclear Information System (INIS)

    Goldobin, Denis S

    2010-01-01

    Frozen parametric disorder can lead to the appearance of sets of localized convective currents in an otherwise stable (quiescent) fluid layer heated from below. These currents significantly influence the transport of an admixture (or any other passive scalar) along the layer. When the molecular diffusivity of the admixture is small in comparison to the thermal one, which is quite typical in nature, disorder can enhance the effective (eddy) diffusivity by several orders of magnitude in comparison to the molecular diffusivity. In this paper, we study the effect of an imposed longitudinal advection on the delocalization of convective currents, both numerically and analytically, and report a subsequent drastic boost of the effective diffusivity for weak advection.

  18. Applications of CIVA NDE 10 on Eddy Current Modeling

    International Nuclear Information System (INIS)

    Nurul Ain Ahmad Latif; Ilham Mukhriz Zainal Abidin; AABdul Razak Hamzah

    2011-01-01

    CIVA NDE 10 is the simulation software and used as the platform to develop the models dedicated to Eddy Current testing (ET). It has various application in semi analytical modeling approaches. The focus of this paper is to simulate the signals response on the 40 % external groove of the Inconel 600 heat exchanger tubes with outside diameter of 22.22 mm. The inspection were simulated using 17 mm outside diameter differential probe with 100 kHz and 500 kHZ testing frequency. All the simulation results were validated using the experimental results integrated in the CIVA software. The configurations of the probe and tube consisting the flaw show the good agreement between the experimental and the simulated data. (author)

  19. Large eddy simulation of a wing-body junction flow

    Science.gov (United States)

    Ryu, Sungmin; Emory, Michael; Campos, Alejandro; Duraisamy, Karthik; Iaccarino, Gianluca

    2014-11-01

    We present numerical simulations of the wing-body junction flow experimentally investigated by Devenport & Simpson (1990). Wall-junction flows are common in engineering applications but relevant flow physics close to the corner region is not well understood. Moreover, performance of turbulence models for the body-junction case is not well characterized. Motivated by the insufficient investigations, we have numerically investigated the case with Reynolds-averaged Naiver-Stokes equation (RANS) and Large Eddy Simulation (LES) approaches. The Vreman model applied for the LES and SST k- ω model for the RANS simulation are validated focusing on the ability to predict turbulence statistics near the junction region. Moreover, a sensitivity study of the form of the Vreman model will also be presented. This work is funded under NASA Cooperative Agreement NNX11AI41A (Technical Monitor Dr. Stephen Woodruff)

  20. Large Eddy Simulations of turbulent flows at supercritical pressure

    Energy Technology Data Exchange (ETDEWEB)

    Kunik, C.; Otic, I.; Schulenberg, T., E-mail: claus.kunik@kit.edu, E-mail: ivan.otic@kit.edu, E-mail: thomas.schulenberg@kit.edu [Karlsruhe Inst. of Tech. (KIT), Karlsruhe (Germany)

    2011-07-01

    A Large Eddy Simulation (LES) method is used to investigate turbulent heat transfer to CO{sub 2} at supercritical pressure for upward flows. At those pressure conditions the fluid undergoes strong variations of fluid properties in a certain temperature range, which can lead to a deterioration of heat transfer (DHT). In this analysis, the LES method is applied on turbulent forced convection conditions to investigate the influence of several subgrid scale models (SGS-model). At first, only velocity profiles of the so-called inflow generator are considered, whereas in the second part temperature profiles of the heated section are investigated in detail. The results are statistically analyzed and compared with DNS data from the literature. (author)

  1. Detached Eddy Simulation of Flap Side-Edge Flow

    Science.gov (United States)

    Balakrishnan, Shankar K.; Shariff, Karim R.

    2016-01-01

    Detached Eddy Simulation (DES) of flap side-edge flow was performed with a wing and half-span flap configuration used in previous experimental and numerical studies. The focus of the study is the unsteady flow features responsible for the production of far-field noise. The simulation was performed at a Reynolds number (based on the main wing chord) of 3.7 million. Reynolds Averaged Navier-Stokes (RANS) simulations were performed as a precursor to the DES. The results of these precursor simulations match previous experimental and RANS results closely. Although the present DES simulations have not reached statistical stationary yet, some unsteady features of the developing flap side-edge flowfield are presented. In the final paper it is expected that statistically stationary results will be presented including comparisons of surface pressure spectra with experimental data.

  2. Quality and Reliability of Large-Eddy Simulations II

    CERN Document Server

    Salvetti, Maria Vittoria; Meyers, Johan; Sagaut, Pierre

    2011-01-01

    The second Workshop on "Quality and Reliability of Large-Eddy Simulations", QLES2009, was held at the University of Pisa from September 9 to September 11, 2009. Its predecessor, QLES2007, was organized in 2007 in Leuven (Belgium). The focus of QLES2009 was on issues related to predicting, assessing and assuring the quality of LES. The main goal of QLES2009 was to enhance the knowledge on error sources and on their interaction in LES and to devise criteria for the prediction and optimization of simulation quality, by bringing together mathematicians, physicists and engineers and providing a platform specifically addressing these aspects for LES. Contributions were made by leading experts in the field. The present book contains the written contributions to QLES2009 and is divided into three parts, which reflect the main topics addressed at the workshop: (i) SGS modeling and discretization errors; (ii) Assessment and reduction of computational errors; (iii) Mathematical analysis and foundation for SGS modeling.

  3. Large Eddy Simulation (LES for IC Engine Flows

    Directory of Open Access Journals (Sweden)

    Kuo Tang-Wei

    2013-10-01

    Full Text Available Numerical computations are carried out using an engineering-level Large Eddy Simulation (LES model that is provided by a commercial CFD code CONVERGE. The analytical framework and experimental setup consist of a single cylinder engine with Transparent Combustion Chamber (TCC under motored conditions. A rigorous working procedure for comparing and analyzing the results from simulation and high speed Particle Image Velocimetry (PIV experiments is documented in this work. The following aspects of LES are analyzed using this procedure: number of cycles required for convergence with adequate accuracy; effect of mesh size, time step, sub-grid-scale (SGS turbulence models and boundary condition treatments; application of the proper orthogonal decomposition (POD technique.

  4. Eddy current distribution and lift force for finite MAGLEV strips

    Energy Technology Data Exchange (ETDEWEB)

    Atherton, D L; Eastham, A R; Fombrun, C; Chong, M

    1974-07-01

    The transverse distribution of induced eddy currents across a flat conducing strip of finite width, due to a rectangular dc magnet moving above it, was modelled experimentally, and was compared with that calculated for an infinite sheet. The electrodynamic suspension was simulated by means of a stationary ac-excited copper magnet suspended above an aluminum strip, and the induced surface current density was measured by a voltage pickup probe connected to a lock-in amplifier. The effect of reducing strip width is examined and shown to produce high current densities close to the edges. These results are related to the variation of lift force with strip width, determined by impedance modelling. A slight enhancement of lift is evident for intermediate strip widths.

  5. Detection of foreign objects using bobbin probe eddy current test

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hee Sung; Kweon, Young Ho; Lee, Dong Ha; Shin, Wook Jo; Yim, Chan Ki [ECT Group, Sae-An Engineering Corporation, Seoul (Korea, Republic of)

    2016-08-15

    Residual foreign objects at the secondary side (top of the tubesheet and tube support plates) of a steam generator are likely to cause a leak by causing wear in the tube. The extent of wear is significantly affected by the material, shape, and size of the foreign object, and the corrosion properties of the tube. The presence of foreign objects at the top of the tubesheet and tube support plates has been identified using remote visual inspection methods such as the foreign object search and retrieval and eddy current test (ECT). The detection of the residual foreign object at the secondary side of a steam generator has limitations that depend on the material properties and the condition of contact with the tube. In this study, which is vertical and horizontal from the upper tubesheet, the corresponding bobbin ECT signals were collected and analyzed to measure its ability to detect foreign objects.

  6. Large Eddy Simulation for Incompressible Flows An Introduction

    CERN Document Server

    Sagaut, P

    2005-01-01

    The first and most exhaustive work of its kind devoted entirely to the subject, Large Eddy Simulation presents a comprehensive account and a unified view of this young but very rich discipline. LES is the only efficient technique for approaching high Reynolds numbers when simulating industrial, natural or experimental configurations. The author concentrates on incompressible fluids and chooses his topics in treating with care both the mathematical ideas and their applications. The book addresses researchers as well as graduate students and engineers. The second edition was a greatly enriched version motivated both by the increasing theoretical interest in LES and the increasing number of applications. Two entirely new chapters were devoted to the coupling of LES with multiresolution multidomain techniques and to the new hybrid approaches that relate the LES procedures to the classical statistical methods based on the Reynolds-Averaged Navier-Stokes equations. This 3rd edition adds various sections to the text...

  7. Generating wind fluctuations for Large Eddy Simulation inflow boundary condition

    International Nuclear Information System (INIS)

    Bekele, S.A.; Hangan, H.

    2004-01-01

    Large Eddy Simulation (LES) studies of flows over bluff bodies immersed in a boundary layer wind environment require instantaneous wind characteristics. The influences of the wind environment on the building pressure distribution are a well-established fact in the experimental study of wind engineering. Measured wind data of full or model scale are available only at a limited number of points. A method of obtaining instantaneous wind data at all mesh points of the inlet boundary for LES computation is necessary. Herein previous and new wind inflow generation techniques are presented. The generated wind data is then applied to a LES computation of a channel flow. The characteristics of the generated wind fluctuations in comparison to the measured data and the properties of the flow field computed from these two wind data are discussed. (author)

  8. Large eddy simulation of vortex breakdown behind a delta wing

    International Nuclear Information System (INIS)

    Mary, I.

    2003-01-01

    A large eddy simulation (LES) of a turbulent flow past a 70 deg. sweep angle delta wing is performed and compared with wind tunnel experiments. The angle of attack and the Reynolds number based on the root chord are equal to 27 deg. and 1.6x10 6 , respectively. Due to the high value of the Reynolds number and the three-dimensional geometry, the mesh resolution usually required by LES cannot be reached. Therefore a local mesh refinement technique based on semi-structured grids is proposed, whereas different wall functions are assessed in this paper. The goal is to evaluate if these techniques are sufficient to provide an accurate solution of such flow on available supercomputers. An implicit Miles model is retained for the subgrid scale (SGS) modelling because the resolution is too coarse to take advantage of more sophisticated SGS models. The solution sensitivity to grid refinement in the streamwise and wall normal direction is investigated

  9. Eddy current inspection of weld defects in tubing

    Science.gov (United States)

    Katragadda, G.; Lord, W.

    1992-01-01

    An approach using differential probes for the inspection of weld defects in tubing is studied. Finite element analysis is used to model the weld regions and defects. Impedance plane signals are predicted for different weld defect types and compared wherever possible with signals from actual welds in tubing. Results show that detection and sizing of defects in tubing is possible using differential eddy current techniques. The phase angle of the impedance plane trajectory gives a good indication of the sizing of the crack. Data on the type of defect can be obtained from the shape of the impedance plane trajectory and the phase. Depending on the skin depth, detection of outer wall, inner wall, and subsurface defects is possible.

  10. Large Eddy Simulation of Turbulent Flows in Wind Energy

    DEFF Research Database (Denmark)

    Chivaee, Hamid Sarlak

    This research is devoted to the Large Eddy Simulation (LES), and to lesser extent, wind tunnel measurements of turbulent flows in wind energy. It starts with an introduction to the LES technique associated with the solution of the incompressible Navier-Stokes equations, discretized using a finite......, should the mesh resolution, numerical discretization scheme, time averaging period, and domain size be chosen wisely. A thorough investigation of the wind turbine wake interactions is also conducted and the simulations are validated against available experimental data from external sources. The effect...... Reynolds numbers, and thereafter, the fully-developed infinite wind farm boundary later simulations are performed. Sources of inaccuracy in the simulations are investigated and it is found that high Reynolds number flows are more sensitive to the choice of the SGS model than their low Reynolds number...

  11. Workshops and problems for benchmarking eddy current codes

    Energy Technology Data Exchange (ETDEWEB)

    Turner, L.R.; Davey, K.; Ida, N.; Rodger, D.; Kameari, A.; Bossavit, A.; Emson, C.R.I.

    1988-08-01

    A series of six workshops was held in 1986 and 1987 to compare eddy current codes, using six benchmark problems. The problems included transient and steady-state ac magnetic fields, close and far boundary conditions, magnetic and non-magnetic materials. All the problems were based either on experiments or on geometries that can be solved analytically. The workshops and solutions to the problems are described. Results show that many different methods and formulations give satisfactory solutions, and that in many cases reduced dimensionality or coarse discretization can give acceptable results while reducing the computer time required. A second two-year series of TEAM (Testing Electromagnetic Analysis Methods) workshops, using six more problems, is underway. 12 refs., 15 figs., 4 tabs.

  12. Aero-Acoustic Modelling using Large Eddy Simulation

    International Nuclear Information System (INIS)

    Shen, W Z; Soerensen, J N

    2007-01-01

    The splitting technique for aero-acoustic computations is extended to simulate three-dimensional flow and acoustic waves from airfoils. The aero-acoustic model is coupled to a sub-grid-scale turbulence model for Large-Eddy Simulations. In the first test case, the model is applied to compute laminar flow past a NACA 0015 airfoil at a Reynolds number of 800, a Mach number of 0.2 and an angle of attack of 20 deg. The model is then applied to compute turbulent flow past a NACA 0015 airfoil at a Reynolds number of 100 000, a Mach number of 0.2 and an angle of attack of 20 deg. The predicted noise spectrum is compared to experimental data

  13. Large-eddy simulation of atmospheric flow over complex terrain

    DEFF Research Database (Denmark)

    Bechmann, Andreas

    2007-01-01

    The present report describes the development and validation of a turbulence model designed for atmospheric flows based on the concept of Large-Eddy Simulation (LES). The background for the work is the high Reynolds number k - #epsilon# model, which has been implemented on a finite-volume code...... turbulence model is able to handle both engineering and atmospheric flows and can be run in both RANS or LES mode. For LES simulations a time-dependent wind field that accurately represents the turbulent structures of a wind environment must be prescribed at the computational inlet. A method is implemented...... where the turbulent wind field from a separate LES simulation can be used as inflow. To avoid numerical dissipation of turbulence special care is paid to the numerical method, e.g. the turbulence model is calibrated with the specific numerical scheme used. This is done by simulating decaying isotropic...

  14. Transient and stationary eddies in differing GCM climates

    International Nuclear Information System (INIS)

    Hall, N.M.J.; Valdes, P.J.

    1994-01-01

    The response of transients to changing forcing/boundary conditions can be just as striking as the response of mean fields such as surface temperature. Indeed the two are intimately linked and the extent to which the transients are either controlled by, or shape the mean flow is difficult to quantify. Diagnostics are presented from several GCM equilibrium climate simulations using the UGAMP GCM. These include representations of the present climate: The Last Glacial Maximum and the Jurassic climate (150 M years ago). Changes in the distribution of transient eddy activity are compared with changes in low level baroclinicity to assess the direct response of the storm tracks to local conditions. Budget calculations are also presented to identify the changing roles of different components of the atmospheric circulation in transporting heat and moisture from equator to pole

  15. Large-Eddy-Simulation of turbulent magnetohydrodynamic flows

    Directory of Open Access Journals (Sweden)

    Woelck Johannes

    2017-01-01

    Full Text Available A magnetohydrodynamic turbulent channel flow under the influence of a wallnormal magnetic field is investigated using the Large-Eddy-Simulation technique and k-equation subgrid-scale-model. Therefore, the new solver MHDpisoFoam is implemented in the OpenFOAM CFD-Code. The temporal decay of an initial turbulent field for different magnetic parameters is investigated. The rms values of the averaged velocity fluctuations show a similar, trend for each coordinate direction. 80% of the fluctuations are damped out in the range between 0 < Ha < < 75 at Re = 6675. The trend can be approximated via an exponential of the form exp(−a·Ha, where a is a scaling parameter. At higher Hartmann numbers the fluctuations decrease in an almost linear way. Therefore, the results of this study show that it may be possible to construct a general law for the turbulence damping due to action of magnetic fields.

  16. Workshops and problems for benchmarking eddy current codes

    International Nuclear Information System (INIS)

    Turner, L.R.; Davey, K.; Ida, N.; Rodger, D.; Kameari, A.; Bossavit, A.; Emson, C.R.I.

    1988-08-01

    A series of six workshops was held in 1986 and 1987 to compare eddy current codes, using six benchmark problems. The problems included transient and steady-state ac magnetic fields, close and far boundary conditions, magnetic and non-magnetic materials. All the problems were based either on experiments or on geometries that can be solved analytically. The workshops and solutions to the problems are described. Results show that many different methods and formulations give satisfactory solutions, and that in many cases reduced dimensionality or coarse discretization can give acceptable results while reducing the computer time required. A second two-year series of TEAM (Testing Electromagnetic Analysis Methods) workshops, using six more problems, is underway. 12 refs., 15 figs., 4 tabs

  17. Computer programs for eddy-current defect studies

    International Nuclear Information System (INIS)

    Pate, J.R.; Dodd, C.V.

    1990-06-01

    Several computer programs to aid in the design of eddy-current tests and probes have been written. The programs, written in Fortran, deal in various ways with the response to defects exhibited by four types of probes: the pancake probe, the reflection probe, the circumferential boreside probe, and the circumferential encircling probe. Programs are included which calculate the impedance or voltage change in a coil due to a defect, which calculate and plot the defect sensitivity factor of a coil, and which invert calculated or experimental readings to obtain the size of a defect. The theory upon which the programs are based is the Burrows point defect theory, and thus the calculations of the programs will be more accurate for small defects. 6 refs., 21 figs

  18. Computer programs for eddy-current defect studies

    Energy Technology Data Exchange (ETDEWEB)

    Pate, J. R.; Dodd, C. V. [Oak Ridge National Lab., TN (USA)

    1990-06-01

    Several computer programs to aid in the design of eddy-current tests and probes have been written. The programs, written in Fortran, deal in various ways with the response to defects exhibited by four types of probes: the pancake probe, the reflection probe, the circumferential boreside probe, and the circumferential encircling probe. Programs are included which calculate the impedance or voltage change in a coil due to a defect, which calculate and plot the defect sensitivity factor of a coil, and which invert calculated or experimental readings to obtain the size of a defect. The theory upon which the programs are based is the Burrows point defect theory, and thus the calculations of the programs will be more accurate for small defects. 6 refs., 21 figs.

  19. Reliability of eddy current examination of steam generator tubes

    International Nuclear Information System (INIS)

    Birks, A.S.; Ferris, R.H.; Doctor, P.G.; Clark, R.A.; Spanner, G.E.

    1985-04-01

    A unique study of nondestructive examination reliability is underway at the Pacific Northwest Laboratory under US Nuclear Regulatory Commission sponsorship. Project participants include the Electric Power Research Institute and consortiums from France, Italy, and Japan. This study group has conducted a series of NDE examinations of tubes from a retired-from-service steam generator, using commercially available multifrequency eddy current equipment and ASME procedures. The examination results have been analyzed to identify factors contributing to variations in NDE inspection findings. The reliability of these examinations will then be validated by destructive analyses of the steam generator tubes. The program is expected to contribute to development of a model for steam generator inservice inspection sampling plans and inspection periods, as well as to improved regulatory guidelines for tube plugging

  20. Eddy-driven stratification initiates North Atlantic spring phytoplankton blooms.

    Science.gov (United States)

    Mahadevan, Amala; D'Asaro, Eric; Lee, Craig; Perry, Mary Jane

    2012-07-06

    Springtime phytoplankton blooms photosynthetically fix carbon and export it from the surface ocean at globally important rates. These blooms are triggered by increased light exposure of the phytoplankton due to both seasonal light increase and the development of a near-surface vertical density gradient (stratification) that inhibits vertical mixing of the phytoplankton. Classically and in current climate models, that stratification is ascribed to a springtime warming of the sea surface. Here, using observations from the subpolar North Atlantic and a three-dimensional biophysical model, we show that the initial stratification and resulting bloom are instead caused by eddy-driven slumping of the basin-scale north-south density gradient, resulting in a patchy bloom beginning 20 to 30 days earlier than would occur by warming.

  1. Improved-Delayed-Detached-Eddy Simulation of cavity-induced transition in hypersonic boundary layer

    International Nuclear Information System (INIS)

    Xiao, Lianghua; Xiao, Zhixiang; Duan, Zhiwei; Fu, Song

    2015-01-01

    Highlights: • This work is about hypersonic cavity-induced transition with IDDES approach. • The length-to-width-to-depth ratio of the cavity is 19.9:3.57:1 at AoA −10° and −15°. • Flow remains laminar at −10°, transition occurs at −15° and cavity changed from open to close type. • Streamwise vortices, impingement shock, traveling shocks and exit shock are observed. • Breakdown of these vortices triggering rapid flow transition. - Abstract: Hypersonic flow transition from laminar to turbulent due to the surface irregularities, like local cavities, can greatly affect the surface heating and skin friction. In this work, the hypersonic flows over a three-dimensional rectangular cavity with length-to-width-to-depth ratio, L:W:D, of 19.9:3.57:1 at two angles of attack (AoA) were numerically studied with Improved-Delayed-Detached-Eddy Simulation (IDDES) method to highlight the mechanism of transition triggered by the cavity. The present approach was firstly applied to the transonic flow over M219 rectangular cavity. The results, including the fluctuating pressure and frequency, agreed with experiment well. In the hypersonic case at Mach number about 9.6 the cavity is seen as “open” at AoA of −10° but “closed” at AoA of −15° unconventional to the two-dimensional cavity case where the flow always exhibits closed cavity feature when the length-to-depth ratio L/D is larger than 14. For the open cavity flow, the shear layer is basically steady and the flow maintains laminar. For the closed cavity case, the external flow goes into the cavity and impinges on the bottom floor. High intensity streamwise vortices, impingement shock and exit shock are observed causing breakdown of these vortices triggering rapid flow transition

  2. Very large eddy simulation of the Red Sea overflow

    Science.gov (United States)

    Ilıcak, Mehmet; Özgökmen, Tamay M.; Peters, Hartmut; Baumert, Helmut Z.; Iskandarani, Mohamed

    Mixing between overflows and ambient water masses is a critical problem of deep-water mass formation in the downwelling branch of the meridional overturning circulation of the ocean. Modeling approaches that have been tested so far rely either on algebraic parameterizations in hydrostatic ocean circulation models, or on large eddy simulations that resolve most of the mixing using nonhydrostatic models. In this study, we examine the performance of a set of turbulence closures, that have not been tested in comparison to observational data for overflows before. We employ the so-called very large eddy simulation (VLES) technique, which allows the use of k-ɛ models in nonhydrostatic models. This is done by applying a dynamic spatial filtering to the k-ɛ equations. To our knowledge, this is the first time that the VLES approach is adopted for an ocean modeling problem. The performance of k-ɛ and VLES models are evaluated by conducting numerical simulations of the Red Sea overflow and comparing them to observations from the Red Sea Outflow Experiment (REDSOX). The computations are constrained to one of the main channels transporting the overflow, which is narrow enough to permit the use of a two-dimensional (and nonhydrostatic) model. A large set of experiments are conducted using different closure models, Reynolds numbers and spatial resolutions. It is found that, when no turbulence closure is used, the basic structure of the overflow, consisting of a well-mixed bottom layer (BL) and entraining interfacial layer (IL), cannot be reproduced. The k-ɛ model leads to unrealistic thicknesses for both BL and IL, while VLES results in the most realistic reproduction of the REDSOX observations.

  3. Toward a Mexican eddy covariance network for carbon cycle science

    Science.gov (United States)

    Vargas, Rodrigo; Yépez, Enrico A.

    2011-09-01

    First Annual MexFlux Principal Investigators Meeting; Hermosillo, Sonora, Mexico, 4-8 May 2011; The carbon cycle science community has organized a global network, called FLUXNET, to measure the exchange of energy, water, and carbon dioxide (CO2) between the ecosystems and the atmosphere using the eddy covariance technique. This network has provided unprecedented information for carbon cycle science and global climate change but is mostly represented by study sites in the United States and Europe. Thus, there is an important gap in measurements and understanding of ecosystem dynamics in other regions of the world that are seeing a rapid change in land use. Researchers met under the sponsorship of Red Temática de Ecosistemas and Consejo Nacional de Ciencia y Tecnologia (CONACYT) to discuss strategies to establish a Mexican eddy covariance network (MexFlux) by identifying researchers, study sites, and scientific goals. During the meeting, attendees noted that 10 study sites have been established in Mexico with more than 30 combined years of information. Study sites span from new sites installed during 2011 to others with 9 to 6 years of measurements. Sites with the longest span measurements are located in Baja California Sur (established by Walter Oechel in 2002) and Sonora (established by Christopher Watts in 2005); both are semiarid ecosystems. MexFlux sites represent a variety of ecosystem types, including Mediterranean and sarcocaulescent shrublands in Baja California; oak woodland, subtropical shrubland, tropical dry forest, and a grassland in Sonora; tropical dry forests in Jalisco and Yucatan; a managed grassland in San Luis Potosi; and a managed pine forest in Hidalgo. Sites are maintained with an individual researcher's funds from Mexican government agencies (e.g., CONACYT) and international collaborations, but no coordinated funding exists for a long-term program.

  4. Multiscale eddy simulation for moist atmospheric convection: Preliminary investigation

    Energy Technology Data Exchange (ETDEWEB)

    Stechmann, Samuel N., E-mail: stechmann@wisc.edu [Department of Mathematics, University of Wisconsin-Madison (United States); Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison (United States)

    2014-08-15

    A multiscale computational framework is designed for simulating atmospheric convection and clouds. In this multiscale framework, large eddy simulation (LES) is used to model the coarse scales of 100 m and larger, and a stochastic, one-dimensional turbulence (ODT) model is used to represent the fine scales of 100 m and smaller. Coupled and evolving together, these two components provide a multiscale eddy simulation (MES). Through its fine-scale turbulence and moist thermodynamics, MES allows coarse grid cells to be partially cloudy and to encompass cloudy–clear air mixing on scales down to 1 m; in contrast, in typical LES such fine-scale processes are not represented or are parameterized using bulk deterministic closures. To illustrate MES and investigate its multiscale dynamics, a shallow cumulus cloud field is simulated. The fine-scale variability is seen to take a plausible form, with partially cloudy grid cells prominent near cloud edges and cloud top. From earlier theoretical work, this mixing of cloudy and clear air is believed to have an important impact on buoyancy. However, contrary to expectations based on earlier theoretical studies, the mean statistics of the bulk cloud field are essentially the same in MES and LES; possible reasons for this are discussed, including possible limitations in the present formulation of MES. One difference between LES and MES is seen in the coarse-scale turbulent kinetic energy, which appears to grow slowly in time due to incoherent stochastic fluctuations in the buoyancy. This and other considerations suggest the need for some type of spatial and/or temporal filtering to attenuate undersampling of the stochastic fine-scale processes.

  5. Multiscale eddy simulation for moist atmospheric convection: Preliminary investigation

    International Nuclear Information System (INIS)

    Stechmann, Samuel N.

    2014-01-01

    A multiscale computational framework is designed for simulating atmospheric convection and clouds. In this multiscale framework, large eddy simulation (LES) is used to model the coarse scales of 100 m and larger, and a stochastic, one-dimensional turbulence (ODT) model is used to represent the fine scales of 100 m and smaller. Coupled and evolving together, these two components provide a multiscale eddy simulation (MES). Through its fine-scale turbulence and moist thermodynamics, MES allows coarse grid cells to be partially cloudy and to encompass cloudy–clear air mixing on scales down to 1 m; in contrast, in typical LES such fine-scale processes are not represented or are parameterized using bulk deterministic closures. To illustrate MES and investigate its multiscale dynamics, a shallow cumulus cloud field is simulated. The fine-scale variability is seen to take a plausible form, with partially cloudy grid cells prominent near cloud edges and cloud top. From earlier theoretical work, this mixing of cloudy and clear air is believed to have an important impact on buoyancy. However, contrary to expectations based on earlier theoretical studies, the mean statistics of the bulk cloud field are essentially the same in MES and LES; possible reasons for this are discussed, including possible limitations in the present formulation of MES. One difference between LES and MES is seen in the coarse-scale turbulent kinetic energy, which appears to grow slowly in time due to incoherent stochastic fluctuations in the buoyancy. This and other considerations suggest the need for some type of spatial and/or temporal filtering to attenuate undersampling of the stochastic fine-scale processes

  6. Some thoughts on an eddy current septum magnet

    International Nuclear Information System (INIS)

    Halbach, K.

    1995-01-01

    It is the purpose of this report to describe the thinking and work that went into thoroughly understanding, a specific eddy current septum magnet that will be used in the APS and needs ''fixing.'' The goal is to go beyond mere qualitative understanding and carry the analysis far enough to recognize the real problems of this magnet and to develop the tools to solve them. While it would be very tempting to write this report in very general terms, it would be very difficult to achieve complete generality, and one would risk losing the focus on this specific magnet that needs to have an improved performance. The discussion contains, however, so many generally useful concepts and procedures that it might further be useful for designers of other eddy current septum magnets both at the APS and elsewhere. Since it is necessary not only to have a deep qualitative understanding of several aspects of this type of magnet, but also to quantitatively assess what has to be done to achieve the desired performance, fairly heavy use of mathematical tools was made. In doing so it became clear that the extensive use of these tools is essential not only for this purpose, but also to get the required good qualitative understanding of the device. For instance, it turns out that in this particular instance, an important part of the underlying physics does not become clear until one seems to run into what one might consider, at first, a mathematical problem, whose resolution is not clear until one has found the solution, which then seems ''obvious.'' Even though iron in the septum has a nonlinear relationship between B and H, assuming a constant permeability is sufficient to obtain the information needed to develop a sufficient understanding of the magnet to make some crucial decisions

  7. Circum-Antarctic Shoreward Heat Transport Derived From an Eddy- and Tide-Resolving Simulation

    Science.gov (United States)

    Stewart, Andrew L.; Klocker, Andreas; Menemenlis, Dimitris

    2018-01-01

    Almost all heat reaching the bases of Antarctica's ice shelves originates from warm Circumpolar Deep Water in the open Southern Ocean. This study quantifies the roles of mean and transient flows in transporting heat across almost the entire Antarctic continental slope and shelf using an ocean/sea ice model run at eddy- and tide-resolving (1/48°) horizontal resolution. Heat transfer by transient flows is approximately attributed to eddies and tides via a decomposition into time scales shorter than and longer than 1 day, respectively. It is shown that eddies transfer heat across the continental slope (ocean depths greater than 1,500 m), but tides produce a stronger shoreward heat flux across the shelf break (ocean depths between 500 m and 1,000 m). However, the tidal heat fluxes are approximately compensated by mean flows, leaving the eddy heat flux to balance the net shoreward heat transport. The eddy-driven cross-slope overturning circulation is too weak to account for the eddy heat flux. This suggests that isopycnal eddy stirring is the principal mechanism of shoreward heat transport around Antarctica, though likely modulated by tides and surface forcing.

  8. Correlation of eddy current responses between fatigue cracks and electrical-discharge-machining notches

    Science.gov (United States)

    Seo, Sukho; Choi, Gyudong; Eom, Tae Jhoun; Lee, Bokwon; Lee, Soo Yeol

    2017-07-01

    The eddy current responses of Electrical Discharge Machining (EDM) notches and fatigue cracks are directly compared to verify the reliability of eddy current inspection. The fatigue crack growth tests using a constant load range control mode were conducted to obtain a variety of edge crack sizes, ranging from 0.9 to 6.6 mm for Al alloy and from 0.1 to 3 mm for Ti alloy. EDM notch specimens of Al and Ti alloys were accordingly prepared in lengths similar to that of the fatigued specimen. The crack length was determined by optical microscope and scanning electron microscope. The eddy current responses between the EDM and fatigued specimens with varying notch/crack length were examined using probe sensors at (100-500) kHz and (1-2) MHz for Al and Ti alloys, respectively. The results show a significant difference in the eddy current signal between the two specimens, based on the correlation between the eddy current response and notch/crack length. This suggests that eddy current inspection using the EDM reference specimen is inaccurate in determining the precise crack size, unless the eddy current response data base is obtained from a fatigue-cracked specimen.

  9. Coherent fine scale eddies in turbulence transition of spatially-developing mixing layer

    International Nuclear Information System (INIS)

    Wang, Y.; Tanahashi, M.; Miyauchi, T.

    2007-01-01

    To investigate the relationship between characteristics of the coherent fine scale eddy and a laminar-turbulent transition, a direct numerical simulation (DNS) of a spatially-developing turbulent mixing layer with Re ω,0 = 700 was conducted. On the onset of the transition, strong coherent fine scale eddies appears in the mixing layer. The most expected value of maximum azimuthal velocity of the eddy is 2.0 times Kolmogorov velocity (u k ), and decreases to 1.2u k , which is an asymptotic value in the fully-developed state, through the transition. The energy dissipation rate around the eddy is twice as high compared with that in the fully-developed state. However, the most expected diameter and eigenvalues ratio of strain rate acting on the coherent fine scale eddy are maintained to be 8 times Kolmogorov length (η) and α:β:γ = -5:1:4 in the transition process. In addition to Kelvin-Helmholtz rollers, rib structures do not disappear in the transition process and are composed of lots of coherent fine scale eddies in the fully-developed state instead of a single eddy observed in early stage of the transition or in laminar flow

  10. Automatic Online Lecture Highlighting Based on Multimedia Analysis

    Science.gov (United States)

    Che, Xiaoyin; Yang, Haojin; Meinel, Christoph

    2018-01-01

    Textbook highlighting is widely considered to be beneficial for students. In this paper, we propose a comprehensive solution to highlight the online lecture videos in both sentence- and segment-level, just as is done with paper books. The solution is based on automatic analysis of multimedia lecture materials, such as speeches, transcripts, and…

  11. Small Drinking Water Systems Communication and Outreach Highlights

    Science.gov (United States)

    As part of our small drinking water systems efforts, this poster highlights several communications and outreach highlights that EPA's Office of Research and Development and Office of Water have been undertaking in collaboration with states and the Association of State Drinking Wa...

  12. Eddy current and ultrasonic fuel channel inspection at Karachi Nuclear Power Plant

    International Nuclear Information System (INIS)

    Mayo, W.R.; Alam, M.M.

    1997-01-01

    In November of 1993 and in-service inspection was performed on eight fuel channels in the Karachi Nuclear Power Plant (KANUPP) reactor. The workscope included ultrasonic and eddy current volumetric examinations, and eddy current measurement of pressure-to calandria tube gap. This paper briefly discusses the planning strategy of the ultrasonic and eddy current examinations, and describes the equipment developed to meet the requirements, followed by details of the actual channel inspection campaign. The presented nondestructive examinations assisted in determining fitness for service of KANUPP reactor channels in general, and confirmed that the problems associated with channel G12 were not generic in nature. (author)

  13. Immersed transient eddy current flow metering: a calibration-free velocity measurement technique for liquid metals

    Science.gov (United States)

    Krauter, N.; Stefani, F.

    2017-10-01

    Eddy current flow meters are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system that is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation.

  14. Perturbation-polynomial expansion formulation of 3-D eddy current problems

    International Nuclear Information System (INIS)

    Yeh, H.T.

    1977-01-01

    A pulsed magnetic field is required in Tokamak fusion machines. Eddy currents produced by the pulsed field may produce undesirable effects, e.g., in the mechanical loading of the vacuum vessel, heating in the magnet and structure, and field ripple in the plasma region. A method has been developed earlier to calculate the eddy current produced in a thin object by the linear ramping of a magnetic dipole. We report here extension of the method to calculate the eddy current induced in three-dimensional objects and by pulse coils of general shape. Examples are given

  15. Use of eddy current mixes to solve a weld examination application

    International Nuclear Information System (INIS)

    Ward, R.C.; LaBoissonniere, A.

    1995-01-01

    The augmentation of typical nondestructive (i.e., ultrasound) weld inspection techniques by the use of eddy current tools may significantly enhance the quality and reliability of weld inspections. One recent example is the development of an eddy current technique for use in the examination of BWR core shroud welds, where multi-frequency mixes are used to eliminate signals coming from the weld material so that the examination of the heat affected zone is enhanced. An analysis tool most commonly associated with ultrasound examinations, the C-Scan based on gated information, may be implemented with eddy current data to enhance analysis

  16. Significant Atmospheric Boundary Layer Change Observed above an Agulhas Current Warm Cored Eddy

    Directory of Open Access Journals (Sweden)

    C. Messager

    2016-01-01

    Full Text Available The air-sea impact of a warm cored eddy ejected from the Agulhas Retroflection region south of Africa was assessed through both ocean and atmospheric profiling measurements during the austral summer. The presence of the eddy causes dramatic atmospheric boundary layer deepening, exceeding what was measured previously over such a feature in the region. This deepening seems mainly due to the turbulent heat flux anomaly above the warm eddy inducing extensive deep and persistent changes in the atmospheric boundary layer thermodynamics. The loss of heat by turbulent processes suggests that this kind of oceanic feature is an important and persistent source of heat for the atmosphere.

  17. Three-dimensional analysis of eddy current with the finite element method

    International Nuclear Information System (INIS)

    Takano, Ichiro; Suzuki, Yasuo

    1977-05-01

    The finite element method is applied to three-dimensional analysis of eddy current induced in a large Tokamak device (JT-60). Two techniques to study the eddy current are presented: those of ordinary vector potential and modified vector potential. The latter is originally developed for decreasing dimension of the global matrix. Theoretical treatment of these two is given. The skin effect for alternate current flowing in the circular loop of rectangular cross section is examined as an example of the modified vector potential technique, and the result is compared with analytical one. This technique is useful in analysis of the eddy current problem. (auth.)

  18. Analysis of eddy current losses during discharging period in a 600 kJ SMES

    International Nuclear Information System (INIS)

    Park, M.J.; Kwak, S.Y.; Lee, S.Y.; Kim, W.S.; Lee, J.K.; Park, C.; Choi, K.; Bae, J.H.; Kim, S.H.; Sim, K.D.; Seong, K.C.; Jung, H.K.; Hahn, S.

    2008-01-01

    The operation of the SMES system can be divided into three modes such as charging, operating and discharging. During the charging and the discharging modes, a magnetic field variation due to the current increase and decrease generate eddy current losses in the SMES system. The eddy current loss in discharging mode is the major factor to be considered because the operating time in the mode is fixed, whereas the charging mode has the arbitrary operating time which is not fixed. In this paper, we present the analysis results of the eddy current losses which are generated in the 600 kJ class HTS SMES system during the discharging mode

  19. Eddy diffusion coefficients and their upper limits based on application of the similarity theory

    Directory of Open Access Journals (Sweden)

    M. N. Vlasov

    2015-07-01

    Full Text Available The equation for the diffusion velocity in the mesosphere and the lower thermosphere (MLT includes the terms for molecular and eddy diffusion. These terms are very similar. For the first time, we show that, by using the similarity theory, the same formula can be obtained for the eddy diffusion coefficient as the commonly used formula derived by Weinstock (1981. The latter was obtained by taking, as a basis, the integral function for diffusion derived by Taylor (1921 and the three-dimensional Kolmogorov kinetic energy spectrum. The exact identity of both formulas means that the eddy diffusion and heat transport coefficients used in the equations, both for diffusion and thermal conductivity, must meet a criterion that restricts the outer eddy scale to being much less than the scale height of the atmosphere. This requirement is the same as the requirement that the free path of molecules must be much smaller than the scale height of the atmosphere. A further result of this criterion is that the eddy diffusion coefficients Ked, inferred from measurements of energy dissipation rates, cannot exceed the maximum value of 3.2 × 106 cm2 s−1 for the maximum value of the energy dissipation rate of 2 W kg−1 measured in the mesosphere and the lower thermosphere (MLT. This means that eddy diffusion coefficients larger than the maximum value correspond to eddies with outer scales so large that it is impossible to use these coefficients in eddy diffusion and eddy heat transport equations. The application of this criterion to the different experimental data shows that some reported eddy diffusion coefficients do not meet this criterion. For example, the large values of these coefficients (1 × 107 cm2 s−1 estimated in the Turbulent Oxygen Mixing Experiment (TOMEX do not correspond to this criterion. The Ked values inferred at high latitudes by Lübken (1997 meet this criterion for summer and winter polar data, but the Ked values for summer at low latitudes

  20. Immersed transient eddy current flow metering: a calibration-free velocity measurement technique for liquid metals

    International Nuclear Information System (INIS)

    Krauter, N; Stefani, F

    2017-01-01

    Eddy current flow meters are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system that is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation. (paper)

  1. Application of wavelet analysis to signal processing methods for eddy-current test

    International Nuclear Information System (INIS)

    Chen, G.; Yoneyama, H.; Yamaguchi, A.; Uesugi, N.

    1998-01-01

    This study deals with the application of wavelet analysis to detection and characterization of defects from eddy-current and ultrasonic testing signals of a low signal-to-noise ratio. Presented in this paper are the methods for processing eddy-current testing signals of heat exchanger tubes of a steam generator in a nuclear power plant. The results of processing eddy-current testing signals of tube testpieces with artificial flaws show that the flaw signals corrupted by noise and/or non-defect signals can be effectively detected and characterized by using the wavelet methods. (author)

  2. Development of Interior Permanent Magnet Motors with Concentrated Windings for Reducing Magnet Eddy Current Loss

    Science.gov (United States)

    Yamazaki, Katsumi; Kanou, Yuji; Fukushima, Yu; Ohki, Shunji; Nezu, Akira; Ikemi, Takeshi; Mizokami, Ryoichi

    In this paper, we present the development of interior magnet motors with concentrated windings, which reduce the eddy current loss of the magnets. First, the mechanism of the magnet eddy current loss generation is investigated by a simple linear magnetic circuit. Due to the consideration, an automatic optimization method using an adaptive finite element method is carried out to determine the stator and rotor shapes, which decrease the eddy current loss of the magnet. The determined stator and rotor are manufactured in order to proof the effectiveness by the measurement.

  3. An Intrathermocline Eddy and a tropical cyclone in the Bay of Bengal

    OpenAIRE

    Gordon, Arnold L.; Shroyer, Emily; Murty, V. S. N.

    2017-01-01

    The Bay of Bengal, subjected to monsoonal forcing and tropical cyclones, displays a complex field of ocean eddies. On 5 December 2013 a sub-surface vortex or Intrathermocline Eddy (ITE) composed of water characteristic of the Andaman Sea was observed within the thermocline of the western Bay of Bengal. We propose that the ITE was the product of Tropical Cyclone Lehar interaction on 27 November 2013 with a westward propagating surface eddy from the eastern Bay of Bengal. While Lehar?s interact...

  4. Is Domain Highlighting Actually Helpful in Identifying Phishing Web Pages?

    Science.gov (United States)

    Xiong, Aiping; Proctor, Robert W; Yang, Weining; Li, Ninghui

    2017-06-01

    To evaluate the effectiveness of domain highlighting in helping users identify whether Web pages are legitimate or spurious. As a component of the URL, a domain name can be overlooked. Consequently, browsers highlight the domain name to help users identify which Web site they are visiting. Nevertheless, few studies have assessed the effectiveness of domain highlighting, and the only formal study confounded highlighting with instructions to look at the address bar. We conducted two phishing detection experiments. Experiment 1 was run online: Participants judged the legitimacy of Web pages in two phases. In Phase 1, participants were to judge the legitimacy based on any information on the Web page, whereas in Phase 2, they were to focus on the address bar. Whether the domain was highlighted was also varied. Experiment 2 was conducted similarly but with participants in a laboratory setting, which allowed tracking of fixations. Participants differentiated the legitimate and fraudulent Web pages better than chance. There was some benefit of attending to the address bar, but domain highlighting did not provide effective protection against phishing attacks. Analysis of eye-gaze fixation measures was in agreement with the task performance, but heat-map results revealed that participants' visual attention was attracted by the highlighted domains. Failure to detect many fraudulent Web pages even when the domain was highlighted implies that users lacked knowledge of Web page security cues or how to use those cues. Potential applications include development of phishing prevention training incorporating domain highlighting with other methods to help users identify phishing Web pages.

  5. Highlighting material structure with transmission electron diffraction correlation coefficient maps

    International Nuclear Information System (INIS)

    Kiss, Ákos K.; Rauch, Edgar F.; Lábár, János L.

    2016-01-01

    Correlation coefficient maps are constructed by computing the differences between neighboring diffraction patterns collected in a transmission electron microscope in scanning mode. The maps are shown to highlight material structural features like grain boundaries, second phase particles or dislocations. The inclination of the inner crystal interfaces are directly deduced from the resulting contrast. - Highlights: • We propose a novel technique to image the structure of polycrystalline TEM-samples. • Correlation coefficients maps highlights the evolution of the diffracting signal. • 3D views of grain boundaries are provided for nano-particles or polycrystals.

  6. Special journal issue highlights IDRC-supported findings on ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2018-03-08

    Mar 8, 2018 ... Special journal issue highlights IDRC-supported findings on women's paid work ... An important aspect of women's economic empowerment is their participation in the labour ... Maternal health research concerns men too.

  7. EMSL Quarterly Highlights Report: FY 2008, 3rd Quarter

    Energy Technology Data Exchange (ETDEWEB)

    Showalter, Mary Ann

    2008-09-16

    The EMSL Quarterly Highlights Report covers the science, staff and user recognition, and publication activities that occurred during the 1st quarter (October 2007 - December 2007) of Fiscal Year 2008.

  8. EMSL Quarterly Highlights Report: 1st Quarter, FY08

    Energy Technology Data Exchange (ETDEWEB)

    Showalter, Mary Ann

    2008-01-28

    The EMSL Quarterly Highlights Report covers the science, staff and user recognition, and publication activities that occurred during the 1st quarter (October 2007 - December 2007) of Fiscal Year 2008.

  9. Highlight: IDRC at the World Congress on Public Health 2015 ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2016-04-14

    Apr 14, 2016 ... ... and communication tools such as radio jingles and internet messages. ... They highlighted best practices in Thailand, which has an effective ... for Health Sciences, Kunming Medical University, Yunnan Province, China.

  10. 2016 Highlights of Ferry Operations in the United States

    Science.gov (United States)

    2017-10-01

    This publication highlights data collected by the 2016 NCFO. The Bureau of Transportation Statistics (BTS) conducted the NCFO from April through November 2016, collecting the operational characteristics of the 2015 calendar year ferry operations.

  11. FY17 Transportation and Hydrogen Systems Center Journal Publication Highlights

    Energy Technology Data Exchange (ETDEWEB)

    2017-12-08

    NREL's Transportation and Hydrogen Systems Center published 39 journal articles in fiscal year 2017 highlighting recent research in advanced vehicle technology, alternative fuels, and hydrogen systems.

  12. Highlight: Youth (Un)Employment: Global problems meet local ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2016-07-07

    Jul 7, 2016 ... ... because there is a huge knowledge gap between what we consider formal ... economic development programming, especially for women and youth. ... Highlight: Ankara workshop puts minimum wage on the G-20 radar.

  13. EMSL Quarterly Highlights Report: 1st Quarter, Fiscal Year 2009

    Energy Technology Data Exchange (ETDEWEB)

    Showalter, Mary Ann; Kathmann, Loel E.; Manke, Kristin L.

    2009-02-02

    The EMSL Quarterly Highlights Report covers the science, staff and user recognition, and publication activities that occurred during the 1st quarter (October 2008 - December 2008) of Fiscal Year 2009.

  14. Physical and Life Sciences 2008 Science & Technology Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Correll, D L; Hazi, A U

    2009-05-06

    This document highlights the outstanding research and development activities in the Physical and Life Sciences Directorate that made news in 2008. It also summarizes the awards and recognition received by members of the Directorate in 2008.

  15. Eddy current loss calculation and thermal analysis of axial-flux permanent magnet couplers

    Directory of Open Access Journals (Sweden)

    Di Zheng

    2017-02-01

    Full Text Available A three-dimensional magnetic field analytical model of axial-flux permanent magnet couplers is presented to calculate the eddy current loss, and the prediction of the copper plate temperature under various loads is analyzed. The magnetic field distribution is calculated, and then the eddy current loss is obtained, with the magnetic field analytical model established in cylindrical coordinate. The influence of various loads on eddy current loss is analyzed. Furthermore, a thermal model of axial-flux permanent magnet couplers is established by taking the eddy current loss as the heat source, using the electromagnetic-thermal coupled method. With the help of the thermal model, the influence of various loads on copper plate temperature rise is also analyzed. The calculated results are compared with the results of finite element method and measurement. The comparison results confirm the validity of the magnetic field analytical model and thermal model.

  16. A Review of Material Properties Estimation Using Eddy Current Testing and Capacitor Imaging

    Directory of Open Access Journals (Sweden)

    Mohd. Amri Yunus

    2009-01-01

    Full Text Available he non destructive testing applications based on inductive (eddy current testing and capacitive sensors are widely used for imaging of material properties. The simple structure, safe to use, low cost, non contact application, good response at medium range frequency of the sensors make them preferable to be used in the industries. The aim of this study is to talk about the material properties estimation applications using eddy current testing and capacitive sensing. The basic operations of eddy current testing and capacitive sensing with example of application in the non destructive testing are discussed. Next, the recent advancements of eddy current testing and capacitive testing in imaging technique are presented in this paper.

  17. A comparison of optical and microwave scintillometers with eddy covariance derived surface heat fluxes

    KAUST Repository

    Yee, Mei Sun; Pauwels, Valentijn R N; Daly, Edoardo; Beringer, Jason; Rü diger, Christoph; McCabe, Matthew; Walker, Jeffrey P.

    2015-01-01

    with an eddy covariance (EC) system, two different makes of optical large aperture scintillometers (LAS) and two microwave scintillometers (MWS) with different frequencies at a pasture site in a semi-arid environment of New South Wales, Australia. We used

  18. Analysis of eddy current induced in track on medium-low speed maglev train

    Science.gov (United States)

    Li, Guanchun; Jia, Zhen; He, Guang; Li, Jie

    2017-06-01

    Electromagnetic levitation (EMS) maglev train relies on the attraction between the electromagnets and rails which are mounted on the train to achieve suspension. During the movement, the magnetic field generated by the electromagnet will induce the eddy current in the orbit and the eddy current will weaken the suspended magnetic field. Which leads to the attenuation of the levitation force, the increases of suspension current and the degradation the suspension performance. In this paper, the influence of eddy current on the air gap magnetic field is solved by theoretical analysis, and the correction coefficient of air gap magnetic field is fitted according to the finite element data. The levitation force and current are calculated by the modified formula, and the velocity curves of the levitation force and current are obtained. The results show that the eddy current effect increases the load power by 61.9% in the case of heavy loads.

  19. Acoustical characteristics and simulated tomographic inversion of a cold core eddy in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Navelkar, G.S.; Murty, T.V.R.; Murty, C.S.

    generalised inverse, based on singular value decomposition technique. The numerical experiment shows that 18 eigen rays with 9 layers enable reconstruction of the eddy profile adequately using 9 eigen modes...

  20. Transient eddies and low frequency variability in the Northern Hemisphere winter climates of two GCMs

    International Nuclear Information System (INIS)

    Hansen, T.; Sutera, A.

    1994-01-01

    An aspect of the climate change problem that is also important to our understanding of the general circulation is the relative roles and interactions between baroclinic-scale transient eddies and the larger scale, lower frequency variability of the flow in midlatitudes. A question may be raised as to how a reduced (or enhanced) level of high-frequency transient eddy activity may influence the character of the large-scale flow. If the transient eddies play an important role in determining the large-scale flow patterns in the atmosphere, then we might expect a profound impact from a changed level of high frequency transient eddy activity on the large-scale flow. An opportunity to address this question is presented by the intercomparison of two general circulation models, the differences in whose formulations lie primarily in their physical parameterizations