WorldWideScience

Sample records for related mhd frontiers

  1. Magnetic fields in Planetary Nebulae: paradigms and related MHD frontiers

    Science.gov (United States)

    Blackman, Eric G.

    2009-04-01

    Many, if not all, post AGB stellar systems swiftly transition from a spherical to a powerful aspherical pre-planetary nebula (pPNE) outflow phase before waning into a PNe. The pPNe outflows require engine rotational energy and a mechanism to extract this energy into collimated outflows. Just radiation and rotation are insufficient but a symbiosis between rotation, differential rotation and large scale magnetic fields remains promising. Present observational evidence for magnetic fields in evolved stars is suggestive of dynamically important magnetic fields, but both theory and observation are rife with research opportunity. I discuss how magnetohydrodynamic outflows might arise in pPNe and PNe and distinguish different between approaches that address shaping vs. those that address both launch and shaping. Scenarios involving dynamos in single stars, binary driven dynamos, or accretion engines cannot be ruled out. One appealing paradigm involves accretion onto the primary post-AGB white dwarf core from a low mass companion whose decaying accretion supply rate owers first the pPNe and then the lower luminosity PNe. Determining observational signatures of different MHD engines is a work in progress. Accretion disk theory and large scale dynamos pose many of their own fundamental challenges, some of which I discuss in a broader context.

  2. Frontiers in Numerical Relativity

    Science.gov (United States)

    Evans, Charles R.; Finn, Lee S.; Hobill, David W.

    2011-06-01

    Preface; Participants; Introduction; 1. Supercomputing and numerical relativity: a look at the past, present and future David W. Hobill and Larry L. Smarr; 2. Computational relativity in two and three dimensions Stuart L. Shapiro and Saul A. Teukolsky; 3. Slowly moving maximally charged black holes Robert C. Ferrell and Douglas M. Eardley; 4. Kepler's third law in general relativity Steven Detweiler; 5. Black hole spacetimes: testing numerical relativity David H. Bernstein, David W. Hobill and Larry L. Smarr; 6. Three dimensional initial data of numerical relativity Ken-ichi Oohara and Takashi Nakamura; 7. Initial data for collisions of black holes and other gravitational miscellany James W. York, Jr.; 8. Analytic-numerical matching for gravitational waveform extraction Andrew M. Abrahams; 9. Supernovae, gravitational radiation and the quadrupole formula L. S. Finn; 10. Gravitational radiation from perturbations of stellar core collapse models Edward Seidel and Thomas Moore; 11. General relativistic implicit radiation hydrodynamics in polar sliced space-time Paul J. Schinder; 12. General relativistic radiation hydrodynamics in spherically symmetric spacetimes A. Mezzacappa and R. A. Matzner; 13. Constraint preserving transport for magnetohydrodynamics John F. Hawley and Charles R. Evans; 14. Enforcing the momentum constraints during axisymmetric spacelike simulations Charles R. Evans; 15. Experiences with an adaptive mesh refinement algorithm in numerical relativity Matthew W. Choptuik; 16. The multigrid technique Gregory B. Cook; 17. Finite element methods in numerical relativity P. J. Mann; 18. Pseudo-spectral methods applied to gravitational collapse Silvano Bonazzola and Jean-Alain Marck; 19. Methods in 3D numerical relativity Takashi Nakamura and Ken-ichi Oohara; 20. Nonaxisymmetric rotating gravitational collapse and gravitational radiation Richard F. Stark; 21. Nonaxisymmetric neutron star collisions: initial results using smooth particle hydrodynamics

  3. Global Health Cooperation: International Relations' New Frontier.

    Science.gov (United States)

    2015-07-01

    This issue of MEDICC Review appears in the wake of a media splash on the reopening of the Cuban and US embassies in Washington and Havana, signaling the renewal of full diplomatic relations between the two governments. Although the US embargo is still law and one of the thorniest bilateral issues remaining, the Obama administration's bold opening towards Cuba is being echoed in the chambers of Senate committees, calling for an end to the policy in place since 1962. Meanwhile, people from the United States have begun to travel to Cuba in droves, and for the first time in many years, we perceive real hope that cooperation may replace hostility-at least in the sectors that most matter to ordinary people in both nations.

  4. Polarization of the Poor: Multivariate Relative Poverty Measurement Sans Frontiers

    OpenAIRE

    Gordon Anderson

    2009-01-01

    A major impediment to poverty evaluation in multivariate environments are the difficulties associated with formulating poverty frontiers. This paper proposes a new multivariate polarization measure which, in appropriate circumstances, works as a multivariate poverty measure which does not require computation of a poverty frontier. As a poverty measure it has the intuitive appeal of reflecting the degree to which societies poor and non-poor are polarized. (The measure would also have considera...

  5. UTSI/CFFF MHD PROGRAM COMPLETION AND RELATED ACTIVITY

    Energy Technology Data Exchange (ETDEWEB)

    Joel W. Muehlhauser

    2004-07-21

    In this final technical report, UTSI summarizes work completed under DOE Contract No. DE-AC22-95PC95231. This work began on the contract effective date, September 15, 1995 and is continuing on a very small basis to complete the groundwater remediation as of this date. The work scope required UTSI to continue to maintain the DOE Coal Fired Flow Facility and keep it in readiness for anticipated testing. This effort was terminated in September 1998 by DOE stop-work letter. Work continued on reporting, environmental restoration and on the High Temperature Superconductivity work that was underway. The work included preparing reports on the MHD POC tests that had been completed just prior to this contract initiation under an earlier contract with DOE Chicago. These four reports are summarized herein. This report summarizes the environmental restoration work performed under the contract, including groundwater monitoring and remediation, removal of wastes from the facility, removal of asbestos from the cooling tower and actions in compliance with the license to discharge water into Woods Reservoir. This report covers work in support of the DOE High Temperature Superconductivity program including: (1) Assistance to DOE in preparing a development plan; (2) Cooperation with industry, national laboratories and other universities to promote the commercialization of thin film superconductors (coated conductors); (3) Process Evaluations; (4) Process Diagnostic Development; and (5) Process Economics. The assistance to DOE task included convening an advisory board composed of all the major participants in the DOE program and preparing a draft development plan and Research and Development Roadmap leading to commercialization of the coated conductor technology. Under this program, cooperative agreements and cooperative work was undertaken with Oak Ridge National Laboratory, Midwest Superconductivity, Inc., EURUS Technologies, Inc., Westinghouse Electric Company, and others. In the

  6. Mapping the frontier of theory in industrial relations

    DEFF Research Database (Denmark)

    Tapia, Maite; Ibsen, Christian Lyhne; Kochan, Thomas A.

    2015-01-01

    The widespread decline of trade unions and the emergence of various alternative forms of worker voice and representation have posed a challenge to the field of industrial relations and generated significant rethinking of the future directions for this field of study. In this article, we examine how...... well industrial relations meta-theories, when combined with efforts to build middle-range theories, provide distinctive explanations and different predictions for the alternatives that have emerged to date to fill the void. We propose new directions for theory and research that expand the range...... of actors or institutions that shape employment relations and include social identities outside of the employment relationship as the basis for mobilizing collective actions and voice. Finally, we suggest using these theoretical arguments to test among alternatives as a means of revitalizing and reshaping...

  7. MHD work related to a self-cooled Pb-17Li blanket with poloidal-radial-toroidal ducts

    Energy Technology Data Exchange (ETDEWEB)

    Reimann, J.; Barleon, L.; Buehler, L. [IATF, Karlsruhe (Germany)] [and others

    1994-12-31

    For self cooled liquid metal blankets MHD pressure drop and velocity distributions are considered as critical issues. This paper summarizes MHD work performed for a DEMO-relevant Pb-17Li blanket which uses essential characteristics of a previous ANL design: The coolant flows downwards in the rear poloidal ducts, turns by 180{degrees} at the blanket bottom and is distributed from the ascending poloidal ducts into short radial channels which feed the toroidal First Wall coolant ducts (aligned with the main magnetic field direction). The flow through the subsequent radial channels is collected again in poloidal channels and the coolant leaves the blanket segment at the top. The blanket design is based on the use of flow channel inserts (FCIs) (which means electrically thin conducting walls for MHD) for all ducts except for the toroidal FW coolant channels. MHD related issues were defined and estimations of corresponding pressure drops were performed. Previous experimental work included a proof of principle of FCIs and a detailed experiment with a single {open_quotes}poloidal{sm_bullet}toroidal{sm_bullet}poloidal{close_quotes} duct (cooperation with ANL). In parallel, a numerical code based on the Core Flow Approximation (CFA) was developed to predict pressure drop and velocity distributions for arbitrary single duct geometries.

  8. The Frontiers of Resource-Related Scientific Research

    Science.gov (United States)

    McNutt, M. K.

    2012-12-01

    Today's and tomorrow's challenges with respect to energy rise beyond assessing the volume, type, distribution, and viability of various energy resources. Access to clean, reliable, and affordable energy supplies requires a much more comprehensive understanding of the full costs, benefits, and inherent risks encompassing the entire life cycle of both the energy commodity/capability itself, as well as those supplementary resources needed for energy production and use, such as water and minerals. Research and assessment science conducted by the US Geological Survey (USGS) spans this range from traditional energy resources such as oil, gas, and coal; to currently under utilized resources such as geothermal, wind, and uranium; as well as more long-term future resources such as gas hydrates. With mission space that includes energy and minerals, water, natural hazards, environmental health, ecosystems, and climate and land use change, increasingly USGS is taking advantage of its integrated science approach and its tradition of working with partners to conduct collaborative research developing methodologies that build on traditional energy-related research. The USGS is incorporating scientific information about geologic, geophysical, biologic, hydrologic, and in some cases socio-economic, trade-offs to be considered by decision makers regarding energy resource development and use. This basic resource information informs the Nation's decisions of how to manage a dynamically evolving energy mix in both an economically and environmentally sustainable manner.

  9. Particle acceleration efficiency and MHD characteristics of CIR-related shocks

    Science.gov (United States)

    Classen, H.-T.; Mann, G.; Keppler, E.

    1998-07-01

    During its southbound journey the Ulysses spacecraft crossed a series of corotating interaction regions (CIRs) building up due to the interaction of fast and slow solar wind streams. We analyse the forward and the reverse shocks marking off the 18 CIR encounters between July 1992 and December 1993. Our investigations look for a correlation between the particle acceleration efficiency expressed by the particle flux measured at the time of shock crossing and the MHD characteristics of the shocks; i.e., Alfven-Mach number (MA1), density and magnetic field compression ratios (r_N, r_B), and the angle between shock normal and upstream magnetic field (theta_ {Bn}). The results of this analysis show that the highest fluxes of 300 keV electrons and 1 MeV protons are observed when the conditions MA1 > 2.5 and 50(deg) <= theta_ {Bn} <= 75(deg) are simultaneously fulfilled by the shocks. These investigations are supplemented by a computation of the first critical Alfven-Mach number for typical parameters of CIR-related shocks. Furthermore, we discuss possible acceleration mechanisms by an analysis of the spectral indices of protons and Helium.

  10. Frontier Analysis

    DEFF Research Database (Denmark)

    Assaf, A. George; Josiassen, Alexander

    2016-01-01

    and macro applications of these approaches, summarizing and critically reviewing the characteristics of the existing studies. We also conduct a meta-analysis to create an overview of the efficiency results of frontier applications. This allows for an investigation of the impact of frontier methodology...

  11. Pregnancy and Beyond: Environmental Frontiers

    OpenAIRE

    Borkenhagen, Rainer H.

    1988-01-01

    Over the last 35 years transport technology has created new environmental frontiers, both in research and in the administration of patient care, in which family physicians are, and will continue to be, involved. Some of these frontiers address basic physiological problems that become interconnected with others. The author describes six of these frontiers, with specific relation to pregnancy, from hyperbarism (undersea physiology) to microgravity (space physiology). He outlines the problems an...

  12. MHD Power Generation

    Science.gov (United States)

    Kantrowitz, Arthur; Rosa, Richard J.

    1975-01-01

    Explains the operation of the Magnetohydrodynamic (MHD) generator and advantages of the system over coal, oil or nuclear powered generators. Details the development of MHD generators in the United States and Soviet Union. (CP)

  13. Frontier constellations

    DEFF Research Database (Denmark)

    Eilenberg, Michael

    2014-01-01

    Borderland regions in Southeast Asia have increasingly been reimagined as resource-rich, unexploited ‘wastelands’ targeted for large-scale development schemes for economic integration and control. Common and overlapping features of these regions are processes of resource extraction, agricultural...... expansion, population resettlement and securitization, and the confluence of these dynamic processes creates special frontier constellations. Through the case of the Indonesian-Malaysian borderlands, I explore how processes of frontier colonization through agricultural expansion have been a recurrent...... contemporary state-capitalist processes of agricultural expansion in the borderlands of Indonesia and other parts of Southeast Asia are justified through discourses of national sovereignty and notions of ‘untamed’ and ‘wild’ resource frontiers. I highlight the multiple meanings and notions associated...

  14. Proceeding of 1998-workshop on MHD computations. Study on numerical methods related to plasma confinement

    Energy Technology Data Exchange (ETDEWEB)

    Kako, T.; Watanabe, T. [eds.

    1999-04-01

    This is the proceeding of 'Study on Numerical Methods Related to Plasma Confinement' held in National Institute for Fusion Science. In this workshop, theoretical and numerical analyses of possible plasma equilibria with their stability properties are presented. These are also various talks on mathematical as well as numerical analyses related to the computational methods for fluid dynamics and plasma physics. The 14 papers are indexed individually. (J.P.N.)

  15. MHD contractors' review meeting

    Science.gov (United States)

    The following research programs on magnetohydrodynamic conversion were described at the contractors' review meeting: MHD integrated topping cycle project; Activity summary for DOE's component development and integration facility; MHD bottoming cycle component testing at the coal fired flow facility; MHD heat recovery seed recovery system development; Diagnostic development and support of MHD test facilities; Heat and seed recovery technology project; TRW Econoseed process for MHD seed recovery and regeneration; and MIT magnet. Papers describe the objectives, the work to date, and results obtained. Papers have been processed separately for inclusion on the data base.

  16. Problems in nonlinear resistive MHD

    Energy Technology Data Exchange (ETDEWEB)

    Turnbull, A.D.; Strait, E.J.; La Haye, R.J.; Chu, M.S.; Miller, R.L. [General Atomics, San Diego, CA (United States)

    1998-12-31

    Two experimentally relevant problems can relatively easily be tackled by nonlinear MHD codes. Both problems require plasma rotation in addition to the nonlinear mode coupling and full geometry already incorporated into the codes, but no additional physics seems to be crucial. These problems discussed here are: (1) nonlinear coupling and interaction of multiple MHD modes near the B limit and (2) nonlinear coupling of the m/n = 1/1 sawtooth mode with higher n gongs and development of seed islands outside q = 1.

  17. Relation between current sheets and vortex sheets in stationary incompressible MHD

    Directory of Open Access Journals (Sweden)

    D. H. Nickeler

    2012-03-01

    Full Text Available Magnetohydrodynamic configurations with strong localized current concentrations and vortices play an important role in the dissipation of energy in space and astrophysical plasma. Within this work we investigate the relation between current sheets and vortex sheets in incompressible, stationary equilibria. For this approach it is helpful that the similar mathematical structure of magnetohydrostatics and stationary incompressible hydrodynamics allows us to transform static equilibria into stationary ones. The main control function for such a transformation is the profile of the Alfvén-Mach number MA, which is always constant along magnetic field lines, but can change from one field line to another. In the case of a global constant MA, vortices and electric current concentrations are parallel. More interesting is the nonlinear case, where MA varies perpendicular to the field lines. This is a typical situation at boundary layers like the magnetopause, heliopause, the solar wind flowing around helmet streamers and at the boundary of solar coronal holes. The corresponding current and vortex sheets show in some cases also an alignment, but not in every case. For special density distributions in 2-D, it is possible to have current but no vortex sheets. In 2-D, vortex sheets of field aligned-flows can also exist without strong current sheets, taking the limit of small Alfvén Mach numbers into account. The current sheet can vanish if the Alfvén Mach number is (almost constant and the density gradient is large across some boundary layer. It should be emphasized that the used theory is not only valid for small Alfvén Mach numbers MA MA ≲ 1. Connection to other theoretical approaches and observations and physical effects in space plasmas are presented. Differences in the various aspects of theoretical investigations of current sheets and vortex sheets are given.

  18. The Relative Efficiencies of Research Universities of Science and Technology in China: Based on the Data Envelopment Analysis and Stochastic Frontier Analysis

    Science.gov (United States)

    Chuanyi, Wang; Xiaohong, Lv; Shikui, Zhao

    2016-01-01

    This paper applies data envelopment analysis (DEA) and stochastic frontier analysis (SFA) to explore the relative efficiency of China's research universities of science and technology. According to the finding, when talent training is the only output, the efficiency of research universities of science and technology is far lower than that of…

  19. Simulating solar MHD

    Directory of Open Access Journals (Sweden)

    M. Schüssler

    Full Text Available Two aspects of solar MHD are discussed in relation to the work of the MHD simulation group at KIS. Photospheric magneto-convection, the nonlinear interaction of magnetic field and convection in a strongly stratified, radiating fluid, is a key process of general astrophysical relevance. Comprehensive numerical simulations including radiative transfer have significantly improved our understanding of the processes and have become an important tool for the interpretation of observational data. Examples of field intensification in the solar photosphere ('convective collapse' are shown. The second line of research is concerned with the dynamics of flux tubes in the convection zone, which has far-reaching implications for our understanding of the solar dynamo. Simulations indicate that the field strength in the region where the flux is stored before erupting to form sunspot groups is of the order of 105 G, an order of magnitude larger than previous estimates based on equipartition with the kinetic energy of convective flows.

    Key words. Solar physics · astrophysics and astronomy (photosphere and chromosphere; stellar interiors and dynamo theory; numerical simulation studies.

  20. EDITORIAL: Invited papers from the international meeting on 'New Frontiers in Numerical Relativity' (Albert Einstein Institute, Potsdam, Germany, 17 21 July 2006)

    Science.gov (United States)

    Campanelli, M.; Rezzolla, L.

    2007-06-01

    Traditionally, frontiers represent a treacherous terrain to venture into, where hidden obstacles are present and uncharted territories lie ahead. At the same time, frontiers are also a place where new perspectives can be appreciated and have often been the cradle of new and thriving developments. With this in mind and inspired by this spirit, the Numerical Relativity Group at the Albert Einstein Institute (AEI) organized a `New Frontiers in Numerical Relativity' meeting on 17 21 July 2006 at the AEI campus in Potsdam, Germany. It is an interesting historical remark that the suggestion of the meeting was first made in the late summer of 2005 and thus at a time that for many reasons has been a turning point in the recent history of numerical relativity. A few months earlier (April 2005) in fact, F Pretorius had announced the first multi-orbit simulations of binary black holes and computed the waveforms from the inspiral, merger and ring-down (`Numerical Relativity', Banff International Research Station, Banff, Canada, 16 21 April 2005). At that time, the work of Pretorius served as an important boost to the research in this field and although no other group has yet adopted the techniques he employed, his results provided the numerical relativity community with clear evidence that the binary black hole problem could be solved. A few months later (November 2005), equally striking results were presented by the NASA Goddard and Texas/Brownsville groups, who also reported, independently, multi-orbit evolutions of binary black holes using numerical techniques and formulations of the Einstein equations which were markedly distinct from those suggested by Pretorius (`Numerical Relativity 2005', Goddard Space Flight Centre, Greenbelt, MD, USA, 2 4 November 2005). A few months later other groups were able to repeat the same simulations and obtain equivalent results, testifying that the community as a whole had reached comparable levels of maturity in both the numerical

  1. Frontiers in Superconducting Materials

    CERN Document Server

    Narlikar, Anant V

    2005-01-01

    Frontiers in Superconducting Materials gives a state-of-the-art report of the most important topics of the current research in superconductive materials and related phenomena. It comprises 30 chapters written by renowned international experts in the field. It is of central interest to researchers and specialists in Physics and Materials Science, both in academic and industrial research, as well as advanced students. It also addresses electronic and electrical engineers. Even non-specialists interested in superconductivity might find some useful answers.

  2. Non-Celiac Gluten Sensitivity: The New Frontier of Gluten Related Disorders

    Science.gov (United States)

    Catassi, Carlo; Bai, Julio C.; Bonaz, Bruno; Bouma, Gerd; Calabrò, Antonio; Carroccio, Antonio; Castillejo, Gemma; Ciacci, Carolina; Cristofori, Fernanda; Dolinsek, Jernej; Francavilla, Ruggiero; Elli, Luca; Green, Peter; Holtmeier, Wolfgang; Koehler, Peter; Koletzko, Sibylle; Meinhold, Christof; Sanders, David; Schumann, Michael; Schuppan, Detlef; Ullrich, Reiner; Vécsei, Andreas; Volta, Umberto; Zevallos, Victor; Sapone, Anna; Fasano, Alessio

    2013-01-01

    Non Celiac Gluten sensitivity (NCGS) was originally described in the 1980s and recently a “re-discovered” disorder characterized by intestinal and extra-intestinal symptoms related to the ingestion of gluten-containing food, in subjects that are not affected with either celiac disease (CD) or wheat allergy (WA). Although NCGS frequency is still unclear, epidemiological data have been generated that can help establishing the magnitude of the problem. Clinical studies further defined the identity of NCGS and its implications in human disease. An overlap between the irritable bowel syndrome (IBS) and NCGS has been detected, requiring even more stringent diagnostic criteria. Several studies suggested a relationship between NCGS and neuropsychiatric disorders, particularly autism and schizophrenia. The first case reports of NCGS in children have been described. Lack of biomarkers is still a major limitation of clinical studies, making it difficult to differentiate NCGS from other gluten related disorders. Recent studies raised the possibility that, beside gluten, wheat amylase-trypsin inhibitors and low-fermentable, poorly-absorbed, short-chain carbohydrates can contribute to symptoms (at least those related to IBS) experienced by NCGS patients. In this paper we report the major advances and current trends on NCGS. PMID:24077239

  3. Non-Celiac Gluten Sensitivity: The New Frontier of Gluten Related Disorders

    Directory of Open Access Journals (Sweden)

    Alessio Fasano

    2013-09-01

    Full Text Available Non Celiac Gluten sensitivity (NCGS was originally described in the 1980s and recently a “re-discovered” disorder characterized by intestinal and extra-intestinal symptoms related to the ingestion of gluten-containing food, in subjects that are not affected with either celiac disease (CD or wheat allergy (WA. Although NCGS frequency is still unclear, epidemiological data have been generated that can help establishing the magnitude of the problem. Clinical studies further defined the identity of NCGS and its implications in human disease. An overlap between the irritable bowel syndrome (IBS and NCGS has been detected, requiring even more stringent diagnostic criteria. Several studies suggested a relationship between NCGS and neuropsychiatric disorders, particularly autism and schizophrenia. The first case reports of NCGS in children have been described. Lack of biomarkers is still a major limitation of clinical studies, making it difficult to differentiate NCGS from other gluten related disorders. Recent studies raised the possibility that, beside gluten, wheat amylase-trypsin inhibitors and low-fermentable, poorly-absorbed, short-chain carbohydrates can contribute to symptoms (at least those related to IBS experienced by NCGS patients. In this paper we report the major advances and current trends on NCGS.

  4. An empirical method to measure the relative efficiency of dairy producers using deterministic frontier analysis

    Directory of Open Access Journals (Sweden)

    Shahram RostamPour

    2012-01-01

    Full Text Available The purpose of this paper is to measure the relative efficiencies of various cow husbandries. The proposed model of this paper uses distribution free analysis to measure the performance of different units responsible for taking care of cows. We gather the necessary information of all units including number of cows, amount of internet usage, number of subunits for taking care of cows, amount of forage produced in each province for grazing livestock and average hour per person training courses as independent variables and consider the amount of produced milk as dependent variable. The necessary information are collected from all available units located in different provinces of Iran and the production function is estimated using a linear programming model. The results indicate that the capital city of Iran, Tehran, holds the highest technical efficiency, the lowest efficiency belongs to province of Ilam and other provinces mostly performs poorly.

  5. ASDEX upgrade MHD equilibria reconstruction on distributed workstations

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, W. E-mail: wolfgang.schneider@ipp.mpg.de; McCarthy, P.J.; Lackner, K.; Gruber, O.; Behler, K.; Martin, P.; Merkel, R

    2000-08-01

    The identification of MHD equilibrium states on the ASDEX Upgrade tokamak is a prerequisite for interpreting measurements from a wide range of diagnostics which are correlated with the shape of the plasma. The availability in realtime of plasma parameters related to the MHD state is crucial for controlling the experiment. Function Parameterization is used as a standard tool to determine the position, shape, and other global parameters of the plasma as well as the MHD equilibrium flux surfaces. The recently developed interpretive equilibrium code CLISTE now enables the calculation of MHD equilibria on an intershot timescale. These calculations are parallelized by the use of a Message Passing Interface (MPI)

  6. Network frontier as a metaphor and myth

    Directory of Open Access Journals (Sweden)

    N V Plotichkina

    2017-12-01

    Full Text Available This article considers spatial metaphors of the Internet and the possibility to extrapolate the frontier thesis of F. Turner on the electronic space. The authors believe that information and communication technologies and the digital world have become new spaces for the expansion of states or individuals. That is why there are ongoing scientific debates on the limits and potential of western and electronic frontiers’ metaphors for analytical description of the digital space. The metaphor of the Internet as a western frontier is quite controversial; many authors prefer the electronic frontier analogy as more heuristic and valid for constructing metaphors of the digital reality. The network frontier is defined as a dynamic, elastic and permeable border of social and cultural practices of the network society. The authors estimate the heuristic potential of the concept ‘network frontier’ developed on the basis of integration of the frontier theory and the concept ‘network society’, taking into account the effects of globalization for the study of elastic, permeable and movable border of the network landscape. In the digital world, the spatiality transforms, the geography of the Internet network determines the metamorphosis of the frontier as a contact zone between online and offline spaces, which is dynamic, innovative, encourages mobility, and its permeability depends on the digital competence of citizens. The authors explain the mythology of western and electronic frontier; name the main network frontier myths related to the rhetoric of western frontier myth; describe the main components of the western frontier myth associated with the idea of American exceptionalism; and conclude with the identification of nowadays myths about frontier-men and the online space they master.

  7. Dipole Alignment in Rotating MHD Turbulence

    Science.gov (United States)

    Shebalin, John V.; Fu, Terry; Morin, Lee

    2012-01-01

    We present numerical results from long-term CPU and GPU simulations of rotating, homogeneous, magnetohydrodynamic (MHD) turbulence, and discuss their connection to the spherically bounded case. We compare our numerical results with a statistical theory of geodynamo action that has evolved from the absolute equilibrium ensemble theory of ideal MHD turbulence, which is based on the ideal MHD invariants are energy, cross helicity and magnetic helicity. However, for rotating MHD turbulence, the cross helicity is no longer an exact invariant, although rms cross helicity becomes quasistationary during an ideal MHD simulation. This and the anisotropy imposed by rotation suggests an ansatz in which an effective, nonzero value of cross helicity is assigned to axisymmetric modes and zero cross helicity to non-axisymmetric modes. This hybrid statistics predicts a large-scale quasistationary magnetic field due to broken ergodicity , as well as dipole vector alignment with the rotation axis, both of which are observed numerically. We find that only a relatively small value of effective cross helicity leads to the prediction of a dipole moment vector that is closely aligned (less than 10 degrees) with the rotation axis. We also discuss the effect of initial conditions, dissipation and grid size on the numerical simulations and statistical theory.

  8. MHD Generating system

    Science.gov (United States)

    Petrick, Michael; Pierson, Edward S.; Schreiner, Felix

    1980-01-01

    According to the present invention, coal combustion gas is the primary working fluid and copper or a copper alloy is the electrodynamic fluid in the MHD generator, thereby eliminating the heat exchangers between the combustor and the liquid-metal MHD working fluids, allowing the use of a conventional coalfired steam bottoming plant, and making the plant simpler, more efficient and cheaper. In operation, the gas and liquid are combined in a mixer and the resulting two-phase mixture enters the MHD generator. The MHD generator acts as a turbine and electric generator in one unit wherein the gas expands, drives the liquid across the magnetic field and thus generates electrical power. The gas and liquid are separated, and the available energy in the gas is recovered before the gas is exhausted to the atmosphere. Where the combustion gas contains sulfur, oxygen is bubbled through a side loop to remove sulfur therefrom as a concentrated stream of sulfur dioxide. The combustor is operated substoichiometrically to control the oxide level in the copper.

  9. Frontier use in ATLAS

    CERN Document Server

    Smith, D A; The ATLAS collaboration; DeStefano, J; Dewhurst, A; Donno, F; Dykstra, D; Front, D; Gallas, E; Hawkings, R; Luehring, F; Walker, R

    2010-01-01

    Frontier is a distributed database access system, including data caching, that was developed originally for the CMS experiment. This system has been in production for CMS for some time, providing world-wide access to the experiment's conditions data for all user jobs. The ATLAS experiment, which has had similar problems with global data distribution, investigated the use of the system for ATLAS jobs. After months of trials and verification, ATLAS put the Frontier system into production late in 2009. Frontier now supplies database access for ATLAS jobs at over 50 computing sites. This successful deployment of Frontier in ATLAS will be described, along with the scope of the system and necessary resources.

  10. Proceedings of the workshop on nonlinear MHD and extended MHD

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-01

    Nonlinear MHD simulations have proven their value in interpreting experimental results over the years. As magnetic fusion experiments reach higher performance regimes, more sophisticated experimental diagnostics coupled with ever expanding computer capabilities have increased both the need for and the feasibility of nonlinear global simulations using models more realistic than regular ideal and resistive MHD. Such extended-MHD nonlinear simulations have already begun to produce useful results. These studies are expected to lead to ever more comprehensive simulation models in the future and to play a vital role in fully understanding fusion plasmas. Topics include the following: (1) current state of nonlinear MHD and extended-MHD simulations; (2) comparisons to experimental data; (3) discussions between experimentalists and theorists; (4) /equations for extended-MHD models, kinetic-based closures; and (5) paths toward more comprehensive simulation models, etc. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

  11. Reduced Extended MHD

    Science.gov (United States)

    Morrison, P. J.; Abdelhamid, H. M.; Grasso, D.; Hazeltine, R. D.; Lingam, M.; Tassi, E.

    2015-11-01

    Over the years various reduced fluid models have been obtained for modeling plasmas, with the goal of capturing important physics while maintaining computability. Such models have included the physics contained in various generalizations of Ohm's law, including Hall drift and electron inertia. In a recent publication it was shown that full 3D extended MHD is a Hamiltonian system by finding its noncanonical Poisson bracket. Subsequently, this bracket was shown to be derivable from that for Hall MHD by a series of remarkable transformations, which greatly simplifies the proof of the Jacobi identity and allows one to immediately obtain generalizations of the helicity and cross helicity. In this poster we use this structure to obtain exact reduced fluid models with the effects of full two-fluid theory. Results of numerical computations of collisionless reconnection using an exact reduced 4-field model will be presented and analytical comparisons of mode structure of previous reduced models will be made.

  12. Particle Acceleration by MHD Turbulence

    OpenAIRE

    Cho, Jungyeon; Lazarian, A.

    2005-01-01

    Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call for revisions in the picture of particle acceleration. We make use of the recently established scaling of slow and fast MHD modes in strong and weak MHD turbulence to provide a systematic study of particle acceleration in magnetic pressure (low-$\\beta$) and gaseous pressure (high-$\\beta$) dominated plasmas. We consider the acceleration by large scale compressions in both slow and fast particle diffusion limits. We c...

  13. The Final Frontier

    DEFF Research Database (Denmark)

    Baron, Christian

    2017-01-01

    The concept of the ‘frontier’ plays an important role in understanding the themes that connect survival-oriented science fiction with American history. Building partly on this tradition of the frontier, this chapter seeks to develop the notion of ‘frontier ethics’ as a way of facing moral dilemma...

  14. Frontiers of Fundamental Physics

    CERN Document Server

    2014-01-01

    The 14th annual international symposium “Frontiers of Fundamental Physics” (FFP14) was organized by the OCEVU Labex. It was held in Marseille, on the Saint-Charles Campus of Aix Marseille University (AMU) and had over 280 participants coming from all over the world. FFP Symposium began in India in 1997 and it became itinerant in 2004, through Europe, Canada and Australia. It covers topics in fundamental physics with the objective to enable scholars working in related areas to meet on a single platform and exchange ideas. In addition to highlighting the progress in these areas, the symposium invites the top researchers to reflect on the educational aspects of our discipline. Moreover, the scientific concepts are also discussed through philosophical and epistemological viewpoints. Several eminent scientists, such as the laureates of prestigious awards (Nobel Prize, Fields Medal,…), have already participated in these meetings. The FFP14 Symposium developed around seven main themes, namely: Astroparticle Ph...

  15. Proceeding of 1999-workshop on MHD computations 'study on numerical methods related to plasma confinement'

    Energy Technology Data Exchange (ETDEWEB)

    Kako, T.; Watanabe, T. [eds.

    2000-06-01

    This is the proceeding of 'study on numerical methods related to plasma confinement' held in National Institute for Fusion Science. In this workshop, theoretical and numerical analyses of possible plasma equilibria with their stability properties are presented. There are also various lectures on mathematical as well as numerical analyses related to the computational methods for fluid dynamics and plasma physics. Separate abstracts were presented for 13 of the papers in this report. The remaining 6 were considered outside the subject scope of INIS. (J.P.N.)

  16. Analogue Kerr-like geometries in a MHD inflow

    CERN Document Server

    Noda, Sousuke; Takahashi, Masaaki

    2016-01-01

    We present a model of the analogue black hole in magnetohydrodynamic (MHD) flow. For a two dimensional axisymmetric stationary trans-magnetosonic inflow with a sink, using the dispersion relation of the MHD waves, we introduce the effective geometries for magnetoacoustic waves propagating in the MHD flow. Investigating the properties of the effective potentials for magnetoacoustic rays, we find that the effective geometries can be classified into five types which include analogue spacetimes of the Kerr black hole, ultra spinning stars with ergoregions and spinning stars without ergoregions. We address the effects of the magnetic pressure and the magnetic tension on each magnetoacoustic geometries.

  17. MHD turbulence and distributed chaos

    CERN Document Server

    Bershadskii, A

    2016-01-01

    It is shown, using results of recent direct numerical simulations, that spectral properties of distributed chaos in MHD turbulence with zero mean magnetic field are similar to those of hydrodynamic turbulence. An exception is MHD spontaneous breaking of space translational symmetry, when the stretched exponential spectrum $\\exp(-k/k_{\\beta})^{\\beta}$ has $\\beta=4/7$.

  18. Basic MHD Turbulence

    Science.gov (United States)

    Beresnyak, Andrey

    2013-01-01

    Astrophysical fluids are conductive, magnetized and turbulent. This entails a variety of phenomena, two most basic of which is the dynamo and the energy cascade. Very well known empirically in hydrodynamics so called "zeroth law of turbulence" states that even if viscosity goes to zero, energy dissipation does not, but goes to a constant. It turns out that in MHD not only this still holds true, but another basic law, which I call "zeroth law of dynamo", is valid, namely that if Reynolds numbers are sufficiently high and magnetic energy is low, the latter will grow at a constant rate, which is a fraction of the total dissipation rate. Another point of interest for an astrophysicist is the properties of MHD cascade in the inertial range. I will argue that both theory and numerics favor Kolmogorov -5/3 slope and not -3/2 slope that was reported earlier. The most challenging problem is so-called imbalanced, or cross-helical case which appear whenever there is a localized source of perturbations, such as the Sun for the solar wind turbulence or the central engine in AGN jets. The standard Goldreich-Sridhar model does not apply in this case and it eluded theoretical description for a long time. The keys to understand energy cascades in the imbalanced case are the anisotropies of the Elsasser fields which turn out to be different. I will show the results of one of the highest resolution simulations ever performed, which were very helpful in discriminating between various viable models of MHD turbulence.

  19. The Final Frontier

    DEFF Research Database (Denmark)

    Johansen, Mikkel Willum

    2017-01-01

    The concept of the ‘frontier’ plays an important role in understanding the themes that connect survival-oriented science fiction with American history. Building partly on this tradition of the frontier, this chapter seeks to develop the notion of ‘frontier ethics’ as a way of facing moral dilemmas...... in living conditions, where neglect or reckless behavior may have fatal consequences. Exploring the consequences of such behavior in Tom Godwin’s short story ‘The Cold Equations’ (1954) as well as Ridley Scott’s film, Alien (1979), it argues that such ‘frontier situations’ warrant a change in the general...... premises for making moral judgments that is often not recognized in ethical discussions. In a frontier situation, the failure to respond adequately to life-threatening situations may quickly be interpreted as a moral failure per se – disregarding whether this failure is a result of neglect, recklessness...

  20. Production of MHD fluid

    Science.gov (United States)

    Lacey, James J.; Kurtzrock, Roy C.; Bienstock, Daniel

    1976-08-24

    A hot gaseous fluid of low ash content, suitable for use in open-cycle MHD (magnetohydrodynamic) power generation, is produced by means of a three-stage process comprising (1) partial combustion of a fossil fuel to produce a hot gaseous product comprising CO.sub.2 CO, and H.sub.2 O, (2) reformation of the gaseous product from stage (1) by means of a fluidized char bed, whereby CO.sub.2 and H.sub.2 O are converted to CO and H.sub.2, and (3) combustion of CO and H.sub.2 from stage (2) to produce a low ash-content fluid (flue gas) comprising CO.sub.2 and H.sub.2 O and having a temperature of about 4000.degree. to 5000.degree.F.

  1. Statistical Theory of the Ideal MHD Geodynamo

    Science.gov (United States)

    Shebalin, J. V.

    2012-01-01

    A statistical theory of geodynamo action is developed, using a mathematical model of the geodynamo as a rotating outer core containing an ideal (i.e., no dissipation), incompressible, turbulent, convecting magnetofluid. On the concentric inner and outer spherical bounding surfaces the normal components of the velocity, magnetic field, vorticity and electric current are zero, as is the temperature fluctuation. This allows the use of a set of Galerkin expansion functions that are common to both velocity and magnetic field, as well as vorticity, current and the temperature fluctuation. The resulting dynamical system, based on the Boussinesq form of the magnetohydrodynamic (MHD) equations, represents MHD turbulence in a spherical domain. These basic equations (minus the temperature equation) and boundary conditions have been used previously in numerical simulations of forced, decaying MHD turbulence inside a sphere [1,2]. Here, the ideal case is studied through statistical analysis and leads to a prediction that an ideal coherent structure will be found in the form of a large-scale quasistationary magnetic field that results from broken ergodicity, an effect that has been previously studied both analytically and numerically for homogeneous MHD turbulence [3,4]. The axial dipole component becomes prominent when there is a relatively large magnetic helicity (proportional to the global correlation of magnetic vector potential and magnetic field) and a stationary, nonzero cross helicity (proportional to the global correlation of velocity and magnetic field). The expected angle of the dipole moment vector with respect to the rotation axis is found to decrease to a minimum as the average cross helicity increases for a fixed value of magnetic helicity and then to increase again when average cross helicity approaches its maximum possible value. Only a relatively small value of cross helicity is needed to produce a dipole moment vector that is aligned at approx.10deg with the

  2. MHD program plan, FY 1991

    Science.gov (United States)

    1990-10-01

    The current magnetohydrodynamic MHD program being implemented is a result of a consensus established in public meetings held by the Department of Energy in 1984. The public meetings were followed by the formulation of a June 1984 Coal-Fired MHD Preliminary Transition and Program Plan. This plan focused on demonstrating the proof-of-concept (POC) of coal-fired MHD electric power plants by the early 1990s. MHD test data indicate that while there are no fundamental technical barriers impeding the development of MHD power plants, technical risk remains. To reduce the technical risk three key subsystems (topping cycle, bottoming cycle, and seed regeneration) are being assembled and tested separately. The program does not require fabrication of a complete superconducting magnet, but rather the development and testing of superconductor cables. The topping cycle system test objectives can be achieved using a conventional iron core magnet system already in place at a DOE facility. Systems engineering-derived requirements and analytical modeling to support scale-up and component design guide the program. In response to environmental, economic, engineering, and utility acceptance requirements, design choices and operating modes are tested and refined to provide technical specifications for meeting commercial criteria. These engineering activities are supported by comprehensive and continuing systems analyses to establish realistic technical requirements and cost data. Essential elements of the current program are to: develop technical and environmental data for the integrated MHD topping cycle and bottoming cycle systems through POC testing (1000 and 4000 hours, respectively); design, construct, and operate a POC seed regeneration system capable of processing spent seed materials from the MHD bottoming cycle; prepare conceptual designs for a site specific MHD retrofit plant; and continue supporting research necessary for system testing.

  3. Crossing the Next Frontier

    Science.gov (United States)

    Goldston, R.; Menard, J.; Brooks, J.; Doerner, R.; Gates, D.; Fu, G.-Y.; Gorelenkov, N.; Kaita, R.; Kaye, S.; Kramer, G.; Kugel, H.; Majeski, R.; Ono, M.; Skinner, C.; Strachan, J.; Harris, J.; Maingi, R.; Kotschenreuther, M.; Mahajan, S.; Valanju, P.; Nygren, R.; Ulrickson, M.; Ruzic, D.; Sabbagh, S.; Soukhanovskii, V.

    2007-11-01

    The plasma-material interface is the next frontier in fusion science. ITER's approaches to heat flux and tritium retention do not extrapolate to Demo. Defining questions at this frontier include: Can extremely high radiated-power fraction be consistent with high confinement and low Zeff? Can magnetic flux expansion or edge ergodization reduce heat loads sufficiently? Can tungsten survive with acceptable core radiation and tritium retention? Can liquid metals more effectively handle high heat flux, off-normal loads and tritium exhaust? Answers must be integrated with high-performance, fully steady state plasma operation, avoiding ELMs and eliminating disruptions. The vehicle to cross this frontier is a high-power-density plasma with long pulses, excellent diagnostic access, flexible first wall, divertor, heating, current drive and plasma control systems, extensive deuterium and trace tritium operation, and the ability to test a range of plasma-facing materials at reactor-relevant temperature.

  4. Frontiers in fusion research

    CERN Document Server

    Kikuchi, Mitsuru

    2011-01-01

    Frontiers in Fusion Research provides a systematic overview of the latest physical principles of fusion and plasma confinement. It is primarily devoted to the principle of magnetic plasma confinement, that has been systematized through 50 years of fusion research. Frontiers in Fusion Research begins with an introduction to the study of plasma, discussing the astronomical birth of hydrogen energy and the beginnings of human attempts to harness the Sun's energy for use on Earth. It moves on to chapters that cover a variety of topics such as: * charged particle motion, * plasma kinetic theory, *

  5. MHD-EMP protection guidelines

    Science.gov (United States)

    Barnes, P. R.; Vance, E. F.

    A nuclear detonation at altitudes several hundred kilometers above the earth will severely distort the earth's magnetic field and result in a strong magnetohydrodynamic electromagnetic pulse (MHD-EMP). The geomagnetic disturbance interacts with the soil to induce current and horizontal electric gradients. MHD-EMP, also called E3 since it is the third component of the high-altitude EMP (HEMP), lasts over 100 s after an exoatmospheric burst. MHD-EMP is similar to solar geomagnetic storms in it's global and low frequency (less than 1 Hz) nature except that E3 can be much more intense with a far shorter duration. When the MHD-EMP gradients are integrated over great distances by power lines, communication cables, or other long conductors, the induced voltages are significant. (The horizontal gradients in the soil are too small to induce major responses by local interactions with facilities.) The long pulse waveform for MHD-EMP-induced currents on long lines has a peak current of 200 A and a time-to-half-peak of 100 s. If this current flows through transformer windings, it can saturate the magnetic circuit and cause 60 Hz harmonic production. To mitigate the effects of MHD-EMP on a facility, long conductors must be isolated from the building and the commercial power harmonics and voltage swings must be addressed. The transfer switch would be expected to respond to the voltage fluctuations as long as the harmonics have not interfered with the switch control circuitry. The major sources of MHD-EMP induced currents are the commercial power lines and neutral; neutral current indirect coupling to the facility power or ground system via the metal fence, powered gate, parking lights, etc; metal water pipes; phone lines; and other long conductors that enter or come near the facility. The major source of harmonics is the commercial power system.

  6. MHD Integrated Topping Cycle Project

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-01

    This fourteenth quarterly technical progress report of the MHD Integrated Topping Cycle Project presents the accomplishments during the period November 1, 1990 to January 31, 1991. Testing of the High Pressure Cooling Subsystem electrical isolator was completed. The PEEK material successfully passed the high temperature, high pressure duration tests (50 hours). The Combustion Subsystem drawings were CADAM released. The procurement process is in progress. An equipment specification and RFP were prepared for the new Low Pressure Cooling System (LPCS) and released for quotation. Work has been conducted on confirmation tests leading to final gas-side designs and studies to assist in channel fabrication.The final cathode gas-side design and the proposed gas-side designs of the anode and sidewall are presented. Anode confirmation tests and related analyses of anode wear mechanisms used in the selection of the proposed anode design are presented. Sidewall confirmation tests, which were used to select the proposed gas-side design, were conducted. The design for the full scale CDIF system was completed. A test program was initiated to investigate the practicality of using Avco current controls for current consolidation in the power takeoff (PTO) regions and to determine the cause of past current consolidation failures. Another important activity was the installation of 1A4-style coupons in the 1A1 channel. A description of the coupons and their location with 1A1 channel is presented herein.

  7. MHD Integrated Topping Cycle Project

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    The Magnetohydrodynamics (MHD) Integrated Topping Cycle (ITC) Project represents the culmination of the proof-of-concept (POC) development stage in the US Department of Energy (DOE) program to advance MHD technology to early commercial development stage utility power applications. The project is a joint effort, combining the skills of three topping cycle component developers: TRW, Avco/TDS, and Westinghouse. TRW, the prime contractor and system integrator, is responsible for the 50 thermal megawatt (50 MW{sub t}) slagging coal combustion subsystem. Avco/TDS is responsible for the MHD channel subsystem (nozzle, channel, diffuser, and power conditioning circuits), and Westinghouse is responsible for the current consolidation subsystem. The ITC Project will advance the state-of-the-art in MHD power systems with the design, construction, and integrated testing of 50 MW{sub t} power train components which are prototypical of the equipment that will be used in an early commercial scale MHD utility retrofit. Long duration testing of the integrated power train at the Component Development and Integration Facility (CDIF) in Butte, Montana will be performed, so that by the early 1990's, an engineering data base on the reliability, availability, maintainability and performance of the system will be available to allow scaleup of the prototypical designs to the next development level. This Sixteenth Quarterly Technical Progress Report covers the period May 1, 1991 to July 31, 1991.

  8. Magnetohydrodynamic (MHD) channel corner seal

    Science.gov (United States)

    Spurrier, Francis R.

    1980-01-01

    A corner seal for an MHD duct includes a compressible portion which contacts the duct walls and an insulating portion which contacts the electrodes, sidewall bars and insulators. The compressible portion may be a pneumatic or hydraulic gasket or an open-cell foam rubber. The insulating portion is segmented into a plurality of pieces of the same thickness as the electrodes, insulators and sidewall bars and aligned therewith, the pieces aligned with the insulator being of a different size from the pieces aligned with the electrodes and sidewall bars to create a stepped configuration along the corners of the MHD channel.

  9. Dynamo action in dissipative, forced, rotating MHD turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Shebalin, John V. [Astromaterials Research Office, NASA Johnson Space Center, Houston, Texas 77058-3696 (United States)

    2016-06-15

    Magnetohydrodynamic (MHD) turbulence is an inherent feature of large-scale, energetic astrophysical and geophysical magnetofluids. In general, these are rotating and are energized through buoyancy and shear, while viscosity and resistivity provide a means of dissipation of kinetic and magnetic energy. Studies of unforced, rotating, ideal (i.e., non-dissipative) MHD turbulence have produced interesting results, but it is important to determine how these results are affected by dissipation and forcing. Here, we extend our previous work and examine dissipative, forced, and rotating MHD turbulence. Incompressibility is assumed, and finite Fourier series represent turbulent velocity and magnetic field on a 64{sup 3} grid. Forcing occurs at an intermediate wave number by a method that keeps total energy relatively constant and allows for injection of kinetic and magnetic helicity. We find that 3-D energy spectra are asymmetric when forcing is present. We also find that dynamo action occurs when forcing has either kinetic or magnetic helicity, with magnetic helicity injection being more important. In forced, dissipative MHD turbulence, the dynamo manifests itself as a large-scale coherent structure that is similar to that seen in the ideal case. These results imply that MHD turbulence, per se, may play a fundamental role in the creation and maintenance of large-scale (i.e., dipolar) stellar and planetary magnetic fields.

  10. Ghana's cocoa frontier in transition

    DEFF Research Database (Denmark)

    Knudsen, Michael Helt; Agergaard, Jytte

    2015-01-01

    in the literature for decades. However, how migration flows have changed in response to changing livelihoods dynamics of the frontier and how this has impacted on the development of the frontier has only attracted limited attention. Based on a study of immigration to Ghana's current cocoa frontier in the Western...... Region, this article aims to examine how immigration and frontier dynamics in the Western region are contributing to livelihood transitions and small town development, and how this process is gradually becoming delinked from the production of cocoa. The article focuses on how migration dynamics interlink...... with livelihood opportunities and strategies. It is argued that migrants to the current frontier can be divided into at least four different types based on their migration, settlement and livelihood practices. Accordingly, to understand how the cocoa frontier changes as well as its continuation beyond...

  11. MHD conversion of solar energy. [space electric power system

    Science.gov (United States)

    Lau, C. V.; Decher, R.

    1978-01-01

    Low temperature plasmas wherein an alkali metal vapor is a component are uniquely suited to simultaneously absorb solar radiation by coupling to the resonance lines and produce electrical power by the MHD interaction. This work is an examination of the possibility of developing space power systems which take advantage of concentrated solar power to produce electricity. It is shown that efficient cycles in which expansion work takes place at nearly constant top cycle temperature can be devised. The power density of the solar MHD generator is lower than that of conventional MHD generators because of the relatively high seed concentration required for radiation absorption and the lower flow velocity permitted to avoid total pressure losses due to heating.

  12. Modeling stochastic frontier based on vine copulas

    Science.gov (United States)

    Constantino, Michel; Candido, Osvaldo; Tabak, Benjamin M.; da Costa, Reginaldo Brito

    2017-11-01

    This article models a production function and analyzes the technical efficiency of listed companies in the United States, Germany and England between 2005 and 2012 based on the vine copula approach. Traditional estimates of the stochastic frontier assume that data is multivariate normally distributed and there is no source of asymmetry. The proposed method based on vine copulas allow us to explore different types of asymmetry and multivariate distribution. Using data on product, capital and labor, we measure the relative efficiency of the vine production function and estimate the coefficient used in the stochastic frontier literature for comparison purposes. This production vine copula predicts the value added by firms with given capital and labor in a probabilistic way. It thereby stands in sharp contrast to the production function, where the output of firms is completely deterministic. The results show that, on average, S&P500 companies are more efficient than companies listed in England and Germany, which presented similar average efficiency coefficients. For comparative purposes, the traditional stochastic frontier was estimated and the results showed discrepancies between the coefficients obtained by the application of the two methods, traditional and frontier-vine, opening new paths of non-linear research.

  13. MHD Turbulence and Magnetic Dynamos

    Science.gov (United States)

    Shebalin, John V

    2014-01-01

    Incompressible magnetohydrodynamic (MHD) turbulence and magnetic dynamos, which occur in magnetofluids with large fluid and magnetic Reynolds numbers, will be discussed. When Reynolds numbers are large and energy decays slowly, the distribution of energy with respect to length scale becomes quasi-stationary and MHD turbulence can be described statistically. In the limit of infinite Reynolds numbers, viscosity and resistivity become zero and if these values are used in the MHD equations ab initio, a model system called ideal MHD turbulence results. This model system is typically confined in simple geometries with some form of homogeneous boundary conditions, allowing for velocity and magnetic field to be represented by orthogonal function expansions. One advantage to this is that the coefficients of the expansions form a set of nonlinearly interacting variables whose behavior can be described by equilibrium statistical mechanics, i.e., by a canonical ensemble theory based on the global invariants (energy, cross helicity and magnetic helicity) of ideal MHD turbulence. Another advantage is that truncated expansions provide a finite dynamical system whose time evolution can be numerically simulated to test the predictions of the associated statistical mechanics. If ensemble predictions are the same as time averages, then the system is said to be ergodic; if not, the system is nonergodic. Although it had been implicitly assumed in the early days of ideal MHD statistical theory development that these finite dynamical systems were ergodic, numerical simulations provided sufficient evidence that they were, in fact, nonergodic. Specifically, while canonical ensemble theory predicted that expansion coefficients would be (i) zero-mean random variables with (ii) energy that decreased with length scale, it was found that although (ii) was correct, (i) was not and the expected ergodicity was broken. The exact cause of this broken ergodicity was explained, after much

  14. Generalized similarity method in unsteady two-dimensional MHD ...

    African Journals Online (AJOL)

    Introduced assumptions simplify considered problem in sake of mathematical solving, but adopted physical model is interesting from practical point of view, because its relation with large number of technically significant MHD flows. Obtained partial differential equations can be solved with modern numerical methods for ...

  15. Magnetic levitation and MHD propulsion

    Science.gov (United States)

    Tixador, P.

    1994-04-01

    Magnetic levitation and MHD propulsion are now attracting attention in several countries. Different superconducting MagLev and MHD systems will be described concentrating on, above all, the electromagnetic aspect. Some programmes occurring throughout the world will be described. Magnetic levitated trains could be the new high speed transportation system for the 21st century. Intensive studies involving MagLev trains using superconductivity have been carried out in Japan since 1970. The construction of a 43 km long track is to be the next step. In 1991 a six year programme was launched in the United States to evaluate the performances of MagLev systems for transportation. The MHD (MagnetoHydroDynamic) offers some interesting advantages (efficiency, stealth characteristics, ...) for naval propulsion and increasing attention is being paid towards it nowadays. Japan is also up at the top with the tests of Yamato I, a 260 ton MHD propulsed ship. Depuis quelques années nous assistons à un redémarrage de programmes concernant la lévitation et la propulsion supraconductrices. Différents systèmes supraconducteurs de lévitation et de propulsion seront décrits en examinant plus particulièrement l'aspect électromagnétique. Quelques programmes à travers le monde seront abordés. Les trains à sustentation magnétique pourraient constituer un nouveau mode de transport terrestre à vitesse élevée (500 km/h) pour le 21^e siècle. Les japonais n'ont cessé de s'intéresser à ce système avec bobine supraconductrice. Ils envisagent un stade préindustriel avec la construction d'une ligne de 43 km. En 1991 un programme américain pour une durée de six ans a été lancé pour évaluer les performances des systèmes à lévitation pour le transport aux Etats Unis. La MHD (Magnéto- Hydro-Dynamique) présente des avantages intéressants pour la propulsion navale et un regain d'intérêt apparaît à l'heure actuelle. Le japon se situe là encore à la pointe des d

  16. Frontiers of Optical Spectroscopy

    Science.gov (United States)

    di Bartolo, Baldassare; Forte, Ottavio

    Advanced spectroscopic techniques allow the probing of very small systems and very fast phenomena, conditions that can be considered "extreme" at the present status of our experimentation and knowledge. Quantum dots, nanocrystals and single molecules are examples of the former and events on the femtosecond scale examples of the latter. The purpose of this book is to examine the realm of phenomena of such extreme type and the techniques that permit their investigations. Each author has developed a coherent section of the program starting at a somewhat fundamental level and ultimately reaching the frontier of knowledge in the field in a systematic and didactic fashion.

  17. Frontiers in Magnetic Materials

    CERN Document Server

    Narlikar, Anant V

    2005-01-01

    Frontiers in Magnetic Materials focuses on the current achievements and state-of-the-art advancements in magnetic materials. Several lines of development- High-Tc Superconductivity, Nanotechnology and refined experimental techniques among them – raised knowledge and interest in magnetic materials remarkably. The book comprises 24 chapters on the most relevant topics written by renowned international experts in the field. It is of central interest to researchers and specialists in Physics and Materials Science, both in academic and industrial research, as well as advanced students.

  18. Frontiers in Computer Education

    CERN Document Server

    Zhu, Egui; 2011 International Conference on Frontiers in Computer Education (ICFCE 2011)

    2012-01-01

    This book is the proceedings of the 2011 International Conference on Frontiers in Computer Education (ICFCE 2011) in Sanya, China, December 1-2, 2011. The contributions can be useful for researchers, software engineers, and programmers, all interested in promoting the computer and education development. Topics covered are computing and communication technology, network management, wireless networks, telecommunication, Signal and Image Processing, Machine Learning, educational management, educational psychology, educational system, education engineering, education technology and training.  The emphasis is on methods and calculi for computer science and education technology development, verification and verification tools support, experiences from doing developments, and the associated theoretical problems.

  19. MHD linear instability code user's manual. [MHD2V106

    Energy Technology Data Exchange (ETDEWEB)

    Hicks, H.R.; Wooten, J.W.

    1976-06-01

    This handbook tells the casual user how to run the program MHD2V106, a computer program to determine linear growth rates and eigenmodes for an ideal MHD plasma in a cylinder or toroid of rectangular cross section.

  20. Broken Ergodicity in MHD Turbulence

    Science.gov (United States)

    Shebalin, John V.

    2010-01-01

    Ideal magnetohydrodynamic (MHD) turbulence may be represented by finite Fourier series, where the inherent periodic box serves as a surrogate for a bounded astrophysical plasma. Independent Fourier coefficients form a canonical ensemble described by a Gaussian probability density function containing a Hermitian covariance matrix with positive eigenvalues. The eigenvalues at lowest wave number can be very small, resulting in a large-scale coherent structure: a turbulent dynamo. This is seen in computations and a theoretical explanation in terms of 'broken ergodicity' contains Taylor s theory of force-free states. An important problem for future work is the case of real, i.e., dissipative flows. In real flows, broken ergodicity and coherent structure are still expected to occur in MHD turbulence at the largest scale, as suggested by low resolution simulations. One challenge is to incorporate coherent structure at the largest scale into the theory of turbulent fluctuations at smaller scales.

  1. MHD wave transmission in the Sun's atmosphere

    Science.gov (United States)

    Stangalini, M.; Del Moro, D.; Berrilli, F.; Jefferies, S. M.

    2011-10-01

    Magnetohydrodynamics (MHD) wave propagation inside the Sun's atmosphere is closely related to the magnetic field topology. For example, magnetic fields are able to lower the cutoff frequency for acoustic waves, thus allowing the propagation of waves that would otherwise be trapped below the photosphere into the upper atmosphere. In addition, MHD waves can be either transmitted or converted into other forms of waves at altitudes where the sound speed equals the Alfvén speed. We take advantage of the large field-of-view provided by the IBIS experiment to study the wave propagation at two heights in the solar atmosphere, which is probed using the photospheric Fe 617.3 nm spectral line and the chromospheric Ca 854.2 nm spectral line, and its relationship to the local magnetic field. Among other things, we find substantial leakage of waves with five-minute periods in the chromosphere at the edges of a pore and in the diffuse magnetic field surrounding it. By using spectropolarimetric inversions of Hinode SOT/SP data, we also find a relationship between the photospheric power spectrum and the magnetic field inclination angle. In particular, we identify well-defined transmission peaks around 25° for five-minute waves and around 15° for three-minute waves. We propose a very simple model based on wave transmission theory to explain this behavior. Finally, our analysis of both the power spectra and chromospheric amplification spectra suggests the presence of longitudinal acoustic waves along the magnetic field lines.

  2. Introducing "Frontiers in Zoology"

    Science.gov (United States)

    Heinze, Jürgen; Tautz, Diethard

    2004-09-29

    As a biological discipline, zoology has one of the longest histories. Today it occasionally appears as though, due to the rapid expansion of life sciences, zoology has been replaced by more or less independent sub-disciplines amongst which exchange is often sparse. However, the recent advance of molecular methodology into "classical" fields of biology, and the development of theories that can explain phenomena on different levels of organisation, has led to a re-integration of zoological disciplines promoting a broader than usual approach to zoological questions. Zoology has re-emerged as an integrative discipline encompassing the most diverse aspects of animal life, from the level of the gene to the level of the ecosystem.The new journal Frontiers in Zoology is the first Open Access journal focussing on zoology as a whole. It aims to represent and re-unite the various disciplines that look at animal life from different perspectives and at providing the basis for a comprehensive understanding of zoological phenomena on all levels of analysis. Frontiers in Zoology provides a unique opportunity to publish high quality research and reviews on zoological issues that will be internationally accessible to any reader at no cost.

  3. Discovering neurosurgery: new frontiers.

    Science.gov (United States)

    Rutka, James T

    2011-12-01

    Over the centuries, discoveries of lands unknown, treasures lost and buried, and formulas to delineate physicochemical processes have led to advancements in our understanding of how the world is structured and governed. In science and medicine, discoveries are frequently made following deliberate periods of observation and experimentation to test hypotheses. However, in some instances, discoveries may arise either following a "eureka moment" that transcends rigorous scientific experimentation or following a serendipitous observation. In many instances, scientific discoveries will lead to new inventions that are aimed at improving the manner in which tasks or operations are performed. In this address, some of the key discoveries in science and medicine that have impacted significantly on the field of neurosurgery are described. Some of these include discoveries in neuroanatomy, anesthesiology, infectious diseases, antisepsis, and radiology. Discoveries in the field of molecular science, from the discovery of DNA to next-generation DNA sequencing, which have helped improve the diagnosis and prognosis of neurosurgical patients with conditions such as brain tumors, are also described. In the end, these discoveries have led us to new frontiers in the subspecialty practice of neurosurgery. Navigating our way through these new frontiers will undoubtedly lead to additional discoveries that are unimaginable at present but bound to improve the future care of neurosurgical patients.

  4. Study of MHD Effects on Surface Waves in Liquid Gallium

    Science.gov (United States)

    Fox, W.; Ji, H.; Pace, D.; Rappaport, H.

    2001-10-01

    The liquid metal experiment (LMX) at the Princeton Plasma Physics Laboratory has been constructed to study magnetohydrodynamic (MHD) effects on the propagation of surface waves in liquid metals in an imposed horizontal magnetic field. The physics of liquid metal is of interest generally as a regime of small magnetic Reynolds number MHD and more specifically contributes basic knowledge to the applications of liquid lithium walls in a fusion reactor. Surface waves are driven by a wave driver controlled by a PC-based Labview system. A non-invasive diagnostic measures surface fluctuations at multiple locations accurately by reflecting an array of lasers off the surface and onto a screen recorded by an ICCD camera. The real part of the dispersion relation has been measured precisely and agrees well with a linear theory, revealing the role of surface oxidation. Experiments have also confirmed that a transverse magnetic field does not affect wave propagation, and have qualitatively observed MHD damping (a non-zero imaginary component of the dispersion relation) of waves propagating in a parallel magnetic field. Planned upgrades to LMX will enable quantitative measurement of this MHD damping rate as well as experiments on two-dimensional waves and nonlinear waves. Implications to the liquid metal wall concept in fusion reactors will be discussed.

  5. The Hubble Frontier Fields: Engaging Multiple Audiences in Exploring the Cosmic Frontier

    Science.gov (United States)

    Lawton, Brandon L.; Smith, Denise A.; Summers, Frank; Ryer, Holly; Slivinski, Carolyn; Lotz, Jennifer M.

    2017-06-01

    The Hubble Frontier Fields is a multi-cycle program of six deep-field observations of strong-lensing galaxy clusters taken in parallel with six deep “blank fields.” The three-year long collaborative program began in late 2013 and is led by observations from NASA’s Great Observatories. The observations, now complete, allow astronomers to look deeper into the universe than ever before, and potentially uncover galaxies that are as much as 100 times fainter than what the telescopes can typically observe. The Frontier Fields science program is ideal for informing audiences about scientific advances and topics in STEM. The study of galaxy properties, statistics, optics, and Einstein’s theory of general relativity naturally leverages off of the science returns of the Frontier Fields program. As a result, the Space Telescope Science Institute’s Office of Public Outreach (OPO) has engaged multiple audiences over the past three years to follow the progress of the Frontier Fields.For over two decades, the STScI outreach program has sought to bring the wonders of the universe to the public and engage audiences in the adventure of scientific discovery. In addition, we are leveraging the reach of the new NASA’s Universe of Learning education program to bring the science of the Frontier Fields to informal education audiences. The main underpinnings of the STScI outreach program and the Universe of Learning education program are scientist-educator development teams, partnerships, and an embedded program evaluation component. OPO is leveraging the infrastructure of these education and outreach programs to bring the Frontier Fields science program to the education community and the public in a cost-effective way.This talk will feature highlights over the past three years of the program. We will highlight OPO’s strategies and infrastructure that allows for the quick delivery of groundbreaking science to the education community and public.

  6. Distance to the Pre-industrial Technological Frontier and Economic Development

    OpenAIRE

    Özak, Ömer

    2016-01-01

    This research explores the effects of the geographical distance to the pre-industrial technological frontier on economic development. It establishes theoretically and empirically that there exists a persistent non-monotonic effect of distance to the frontier on development. In particular, exploiting a novel measure of the travel time to the technological frontier and variations in its location during the pre-industrial era, it establishes a robust persistent U-shaped relation between the dis...

  7. Outplacement: The New Counseling Frontier.

    Science.gov (United States)

    Branstead, Elizabeth; And Others

    1991-01-01

    Includes "Outplacement: The New Counseling Frontier" (Branstead); "Interview with Bob Ward"; "Ethics of Outplacement" (Axmith); "Outplacement--The View from Over Here" (Murray); "In-House Outplacement Programs for the 1990s and Beyond" (Benedict); "Government and Outplacement"…

  8. On wave turbulence in MHD

    Directory of Open Access Journals (Sweden)

    S. Galtier

    2001-01-01

    Full Text Available We describe the fundamental differences between weak (wave turbulence in incompressible and weakly compressible MHD at the level of three-wave interactions. The main difference is in the structure of the resonant manifolds and the mechanisms of redistribution of spectral densities along the applied magnetic field B0. Similar to pure acoustic waves, a three-wave resonance between collinear wave vectors is observed but, in addition, we also have a resonance through tilted planes and spheres. The properties of resonances and their consequences for the asymptotics are also discussed.

  9. Ceramic components for MHD electrode

    Science.gov (United States)

    Marchant, D.D.

    A ceramic component which exhibits electrical conductivity down to near room temperatures has the formula: Hf/sub x/In/sub y/A/sub z/O/sub 2/ where x = 0.1 to 0.4, y = 0.3 to 0.6, z = 0.1 to 0.4 and A is a lanthanide rare earth or yttrium. The component is suitable for use in the fabrication of MHD electrodes or as the current leadout portion of a composite electrode with other ceramic components.

  10. Performance and flow characteristics of MHD seawater thruster

    Energy Technology Data Exchange (ETDEWEB)

    Doss, E.D.

    1990-01-01

    The main goal of the research is to investigate the effects of strong magnetic fields on the electrical and flow fields inside MHD thrusters. The results of this study is important in the assessment of the feasibility of MHD seawater propulsion for the Navy. To accomplish this goal a three-dimensional fluid flow computer model has been developed and applied to study the concept of MHD seawater propulsion. The effects of strong magnetic fields on the current and electric fields inside the MHD thruster and their interaction with the flow fields, particularly those in the boundary layers, have been investigated. The results of the three-dimensional computations indicate that the velocity profiles are flatter over the sidewalls of the thruster walls in comparison to the velocity profiles over the electrode walls. These nonuniformities in the flow fields give rise to nonuniform distribution of the skin friction along the walls of the thrusters, where higher values are predicted over the sidewalls relative to those over the electrode walls. Also, a parametric study has been performed using the three-dimensional MHD flow model to analyze the performance of continuous electrode seawater thrusters under different operating parameters. The effects of these parameters on the fluid flow characteristics, and on the thruster efficiency have been investigated. Those parameters include the magnetic field (10--20 T), thruster diameter, surface roughness, flow velocity, and the electric load factor. The results show also that the thruster performance improves with the strength of the magnetic field and thruster diameter, and the efficiency decreases with the flow velocity and surface roughness.

  11. A Study on Neutrosophic Frontier and Neutrosophic Semi-frontier in Neutrosophic Topological Spaces

    Directory of Open Access Journals (Sweden)

    P. Iswarya

    2017-02-01

    Full Text Available In this paper neutrosophic frontier and neutrosophic semi-frontier in neutrosophic topology are introduced and several of their properties, characterizations and examples are established.

  12. Feasibility of MHD submarine propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Doss, E.D. (ed.) (Argonne National Lab., IL (United States)); Sikes, W.C. (ed.) (Newport News Shipbuilding and Dry Dock Co., VA (United States))

    1992-09-01

    This report describes the work performed during Phase 1 and Phase 2 of the collaborative research program established between Argonne National Laboratory (ANL) and Newport News Shipbuilding and Dry Dock Company (NNS). Phase I of the program focused on the development of computer models for Magnetohydrodynamic (MHD) propulsion. Phase 2 focused on the experimental validation of the thruster performance models and the identification, through testing, of any phenomena which may impact the attractiveness of this propulsion system for shipboard applications. The report discusses in detail the work performed in Phase 2 of the program. In Phase 2, a two Tesla test facility was designed, built, and operated. The facility test loop, its components, and their design are presented. The test matrix and its rationale are discussed. Representative experimental results of the test program are presented, and are compared to computer model predictions. In general, the results of the tests and their comparison with the predictions indicate that thephenomena affecting the performance of MHD seawater thrusters are well understood and can be accurately predicted with the developed thruster computer models.

  13. MHD (Magnetohydrodynamics) recovery and regeneration

    Energy Technology Data Exchange (ETDEWEB)

    McIlroy, R. A. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Probert, P. B. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Lahoda, E. J. [Westinghouse Electric Corp., Pittsburgh, PA (United States); Swift, W. M. [Argonne National Lab. (ANL), Argonne, IL (United States); Jackson, D. M. [Univ. of Tennessee Space Inst. (UTSI), Tullahoma, TN (United States); Prasad, J. [Univ. of Tennessee Space Inst. (UTSI), Tullahoma, TN (United States); Martin, J. [Hudson Engineering (United States); Rogers, C. [Hudson Engineering (United States); Ho, K. K. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Senary, M. K. [Babcock and Wilcox Co., Alliance, OH (United States). Research Center; Lee, S. [Univ. of Akron, OH (United States)

    1988-10-01

    A two-phase program investigating MHD seed regeneration is described. In Phase I, bench scale experiments were carried out to demonstrate the technical feasibility of a proposed Seed Regeneration Process. The Phase I data has been used for the preliminary design of a Proof-of-Concept (POC) plant which will be built and tested in Phase II. The Phase I data will also be used to estimate the costs of a 300 Mw(t) demonstration plant for comparison with other processes. The Seed Regeneration Process consists of two major subprocesses; a Westinghouse Dry Reduction process and a modified Tampella (sulfur) Recovery process. The Westinghouse process reduces the recovered spent seed (i.e., potassium sulfate) to potassium polysulfide in a rotary kiln. The reduction product is dissolved in water to form green liquor, clarified to remove residual coal ash, and sent to the Tampella sulfur release system. The sulfur is released using carbon dioxide from flue gas in a two stage reaction. The sulfur is converted to elemental sulfur as a marketable by product. The potassium is crystallized from the green liquor and dried to the anhydrous form for return to the MHD unit.

  14. Coupled generator and combustor performance calculations for potential early commercial MHD power plants

    Science.gov (United States)

    Dellinger, T. C.; Hnat, J. G.; Marston, C. H.

    1979-01-01

    A parametric study of the performance of the MHD generator and combustor components of potential early commercial open-cycle MHD/steam power plants is presented. Consideration is given to the effects of air heater system concept, MHD combustor type, coal type, thermal input power, oxygen enrichment of the combustion, subsonic and supersonic generator flow and magnetic field strength on coupled generator and combustor performance. The best performance is found to be attained with a 3000 F, indirectly fired air heater, no oxygen enrichment, Illinois no. 6 coal, a two-stage cyclone combustor with 85% slag rejection, a subsonic generator, and a magnetic field configuration yielding a constant transverse electric field of 4 kV/m. Results indicate that optimum net MHD generator power is generally compressor-power-limited rather than electric-stress-limited, with optimum net power a relatively weak function of operating pressure.

  15. Frontiers in Chemical Physics

    Energy Technology Data Exchange (ETDEWEB)

    Bowlan, Pamela Renee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-02

    These are slides dealing with frontiers in chemical physics. The following topics are covered: Time resolving chemistry with ultrashort pulses in the 0.1-40 THz spectral range; Example: Mid-infrared absorption spectrum of the intermediate state CH2OO; Tracking reaction dynamics through changes in the spectra; Single-shot measurement of the mid-IR absorption dynamics; Applying 2D coherent mid-IR spectroscopy to learn more about transition states; Time resolving chemical reactions at a catalysis using mid-IR and THz pulses; Studying topological insulators requires a surface sensitive probe; Nonlinear phonon dynamics in Bi2Se3; THz-pump, SHG-probe as a surface sensitive coherent 2D spectroscopy; Nanometer and femtosecond spatiotemporal resolution mid-IR spectroscopy; Coherent two-dimensional THz/mid-IR spectroscopy with 10nm spatial resolution; Pervoskite oxides as catalysts; Functionalized graphene for catalysis; Single-shot spatiotemporal measurements; Spatiotemporal pulse measurement; Intense, broad-band THz/mid-IR generation with organic crystals.

  16. Energy: the microfluidic frontier.

    Science.gov (United States)

    Sinton, David

    2014-09-07

    Global energy is largely a fluids problem. It is also large-scale, in stark contrast to microchannels. Microfluidic energy technologies must offer either massive scalability or direct relevance to energy processes already operating at scale. We have to pick our fights. Highlighted here are the exceptional opportunities I see, including some recent successes and areas where much more attention is needed. The most promising directions are those that leverage high surface-to-volume ratios, rapid diffusive transport, capacity for high temperature and high pressure experiments, and length scales characteristic of microbes and fluids (hydrocarbons, CO2) underground. The most immediate areas of application are where information is the product; either fluid sample analysis (e.g. oil analysis); or informing operations (e.g. CO2 transport in microporous media). I'll close with aspects that differentiate energy from traditional microfluidics applications, the uniquely important role of engineering in energy, and some thoughts for the research community forming at the nexus of lab-on-a-chip and energy--a microfluidic frontier.

  17. Intensity Frontier Instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Kettell S.; Rameika, R.; Tshirhart, B.

    2013-09-24

    The fundamental origin of flavor in the Standard Model (SM) remains a mystery. Despite the roughly eighty years since Rabi asked “Who ordered that?” upon learning of the discovery of the muon, we have not understood the reason that there are three generations or, more recently, why the quark and neutrino mixing matrices and masses are so different. The solution to the flavor problem would give profound insights into physics beyond the Standard Model (BSM) and tell us about the couplings and the mass scale at which the next level of insight can be found. The SM fails to explain all observed phenomena: new interactions and yet unseen particles must exist. They may manifest themselves by causing SM reactions to differ from often very precise predictions. The Intensity Frontier (1) explores these fundamental questions by searching for new physics in extremely rare processes or those forbidden in the SM. This often requires massive and/or extremely finely tuned detectors.

  18. Estimating the NIH efficient frontier.

    Directory of Open Access Journals (Sweden)

    Dimitrios Bisias

    Full Text Available BACKGROUND: The National Institutes of Health (NIH is among the world's largest investors in biomedical research, with a mandate to: "…lengthen life, and reduce the burdens of illness and disability." Its funding decisions have been criticized as insufficiently focused on disease burden. We hypothesize that modern portfolio theory can create a closer link between basic research and outcome, and offer insight into basic-science related improvements in public health. We propose portfolio theory as a systematic framework for making biomedical funding allocation decisions-one that is directly tied to the risk/reward trade-off of burden-of-disease outcomes. METHODS AND FINDINGS: Using data from 1965 to 2007, we provide estimates of the NIH "efficient frontier", the set of funding allocations across 7 groups of disease-oriented NIH institutes that yield the greatest expected return on investment for a given level of risk, where return on investment is measured by subsequent impact on U.S. years of life lost (YLL. The results suggest that NIH may be actively managing its research risk, given that the volatility of its current allocation is 17% less than that of an equal-allocation portfolio with similar expected returns. The estimated efficient frontier suggests that further improvements in expected return (89% to 119% vs. current or reduction in risk (22% to 35% vs. current are available holding risk or expected return, respectively, constant, and that 28% to 89% greater decrease in average years-of-life-lost per unit risk may be achievable. However, these results also reflect the imprecision of YLL as a measure of disease burden, the noisy statistical link between basic research and YLL, and other known limitations of portfolio theory itself. CONCLUSIONS: Our analysis is intended to serve as a proof-of-concept and starting point for applying quantitative methods to allocating biomedical research funding that are objective, systematic, transparent

  19. Application of Magnetohydrodynamics (MHD) and Recent Research Trend

    Science.gov (United States)

    Harada, Nobuhiro

    As the applications of Magnetohydrodynamic (MHD) energy conversion, research and development for high-efficiency and low emission electric power generation system, MHD accelerations and/or MHD thrusters, and flow control around hypersonic and re-entry vehicles are introduced. For closed cycle MHD power generation, high-efficiency MHD single system is the most hopeful system and space power system using mixed inert gas (MIG) working medium is proposed. For open cycle MHD, high-efficiency coal fired MHD system with CO2 recovery has been proposed. As inverse process of MHD power generation, MHD accelerators/thrusters are expected as the next generation propulsion system. Heat flux reduction to protect re-entry vehicles is expected by an MHD process for safety return from space missions.

  20. Cosmological AMR MHD with Enzo

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hao [Los Alamos National Laboratory; Li, Hui [Los Alamos National Laboratory; Li, Shengtai [Los Alamos National Laboratory

    2009-01-01

    In this work, we present EnzoMHD, the extension of the cosmological code Enzoto include magnetic fields. We use the hyperbolic solver of Li et al. (2008) for the computation of interface fluxes. We use constrained transport methods of Balsara & Spicer (1999) and Gardiner & Stone (2005) to advance the induction equation, the reconstruction technique of Balsara (2001) to extend the Adaptive Mesh Refinement of Berger & Colella (1989) already used in Enzo, though formulated in a slightly different way for ease of implementation. This combination of methods preserves the divergence of the magnetic field to machine precision. We use operator splitting to include gravity and cosmological expansion. We then present a series of cosmological and non cosmologjcal tests problems to demonstrate the quality of solution resulting from this combination of solvers.

  1. Disk MHD Conversion System for Nerva Reactor

    National Research Council Canada - National Science Library

    Jackson, W

    1992-01-01

    The principal results of the study have been to: (1) confirm that cesium seeded hydrogen plasma disk MHD generator can meet its expected performance while operating in a stable plasma regime; and (2...

  2. Open Boundary Conditions for Dissipative MHD

    Energy Technology Data Exchange (ETDEWEB)

    Meier, E T

    2011-11-10

    In modeling magnetic confinement, astrophysics, and plasma propulsion, representing the entire physical domain is often difficult or impossible, and artificial, or 'open' boundaries are appropriate. A novel open boundary condition (BC) for dissipative MHD, called Lacuna-based open BC (LOBC), is presented. LOBC, based on the idea of lacuna-based truncation originally presented by V.S. Ryaben'kii and S.V. Tsynkov, provide truncation with low numerical noise and minimal reflections. For hyperbolic systems, characteristic-based BC (CBC) exist for separating the solution into outgoing and incoming parts. In the hyperbolic-parabolic dissipative MHD system, such separation is not possible, and CBC are numerically unstable. LOBC are applied in dissipative MHD test problems including a translating FRC, and coaxial-electrode plasma acceleration. Solution quality is compared to solutions using CBC and zero-normal derivative BC. LOBC are a promising new open BC option for dissipative MHD.

  3. Global MHD simulations of Neptune's magnetosphere

    National Research Council Canada - National Science Library

    Mejnertsen, L; Eastwood, J. P; Chittenden, J. P; Masters, A

    2016-01-01

    A global magnetohydrodynamic (MHD) simulation has been performed in order to investigate the outer boundaries of Neptune's magnetosphere at the time of Voyager 2's flyby in 1989 and to better understand the dynamics of magnetospheres...

  4. Solar driven liquid metal MHD power generator

    Science.gov (United States)

    Lee, J. H.; Hohl, F. (Inventor)

    1983-01-01

    A solar energy collector focuses solar energy onto a solar oven which is attached to a mixer which in turn is attached to the channel of a MHD generator. Gas enters the oven and a liquid metal enters the mixer. The gas/liquid metal mixture is heated by the collected solar energy and moves through the MHD generator thereby generating electrical power. The mixture is then separated and recycled.

  5. Pushing Human Frontiers

    Science.gov (United States)

    Zubrin, Robert

    2005-01-01

    With human colonization of Mars, I think you will see a higher standard of civilization, just as America set a higher standard of civilization which then promulgated back into Europe. I think that if you want to maximize human potential, you need a higher standard of civilization, and that becomes an example that benefits everyone. Without an open frontier, closed world ideologies, such as the Malthus Theory, tend to come to the forefront. It is that there are limited resources; therefore, we are all in deadly competition with each other for the limited pot. The result is tyrannical and potentially genocidal regimes, and we've already seen this in the twentieth century. There s no truth in the Malthus Theory, because human beings are the creators of their resources. With every mouth comes a pair of hands and a brain. But if it seems to be true, you have a vector in this direction, and it is extremely unfortunate. It is only in a universe of infinite resources that all humans can be brothers and sisters. The fundamental question which affects humanity s sense of itself is whether the world is changeable or fixed. Are we the makers of our world or just its inhabitants? Some people have a view that they re living at the end of history within a world that s already defined, and there is no fundamental purpose to human life because there is nothing humans can do that matters. On the other hand, if humans understand their own role as the creators of their world, that s a much more healthy point of view. It raises the dignity of humans. Indeed, if we do establish a new branch of human civilization on Mars that grows in time and potency to the point where it cannot really settle Mars, but transforms Mars, and brings life to Mars, we will prove to everyone and for all time the precious and positive nature of the human species and every member of it.

  6. Energy technology sources, systems and frontier conversion

    CERN Document Server

    Ohta, Tokio

    1994-01-01

    This book provides a concise and technical overview of energy technology: the sources of energy, energy systems and frontier conversion. As well as serving as a basic reference book for professional scientists and students of energy, it is intended for scientists and policy makers in other disciplines (including practising engineers, biologists, physicists, economists and managers in energy related industries) who need an up-to-date and authoritative guide to the field of energy technology.Energy systems and their elemental technologies are introduced and evaluated from the view point

  7. MHD seed recovery and regeneration, Phase II. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1994-10-01

    This final report summarizes the work performed by the Space and Technology Division of the TRW Space and Electronics Group for the U.S. Department of Energy, Pittsburgh Energy Technology Center for the Econoseed process. This process involves the economical recovery and regeneration of potassium seed used in the MHD channel. The contract period of performance extended from 1987 through 1994 and was divided into two phases. The Phase II test results are the subject of this Final Report. However, the Phase I test results are presented in summary form in Section 2.3 of this Final Report. The Econoseed process involves the treatment of the potassium sulfate in spent MHD seed with an aqueous calcium formate solution in a continuously stirred reactor system to solubilize, as potassium formate, the potassium content of the seed and to precipitate and recover the sulfate as calcium sulfate. The slurry product from this reaction is centrifuged to separate the calcium sulfate and insoluble seed constituents from the potassium formate solution. The dilute solids-free potassium formate solution is then concentrated in an evaporator. The concentrated potassium formate product is a liquid which can be recycled as a spray into the MHD channel. Calcium formate is the seed regenerant used in the Econoseed process. Since calcium formate is produced in the United States in relatively small quantities, a new route to the continuous production of large quantities of calcium formate needed to support an MHD power industry was investigated. This route involves the reaction of carbon monoxide gas with lime solids in an aqueous medium.

  8. South African Homelands as Frontiers

    DEFF Research Database (Denmark)

    of frontier zones, the homelands emerge as areas in which the future of the South African postcolony is being renegotiated, contested and remade with hyper-real intensity. This is so because the many fault lines left over from apartheid (its loose ends, so to speak) – between white and black; between...

  9. The Frontiers Approach: Defending a Sufficientarian Rule of Distributive Justice

    DEFF Research Database (Denmark)

    Nielsen, Lasse; Axelsen, David Vestergaard

    2012-01-01

    justice takes its starting point in duress as the relevant contrast to dignity. Human dignity, we define by expanding Kant’s notion of dignity as the moral worth of autonomous, rational persons to entail emotional valuable aspects of the human life and the praxis of embracing these aspects...... of justice. This scheme suggests two separate thresholds, one of which relates to the moral importance of upholding people’s mere potential of a dignified human life (the potentiality frontier), the other to the actual attainment of human dignity (the dignity frontier). The advantage of such a reconstruction...

  10. Pulse Detonation Rocket MHD Power Experiment

    Science.gov (United States)

    Litchford, Ron J.; Cook, Stephen (Technical Monitor)

    2002-01-01

    A pulse detonation research engine (MSFC (Marshall Space Flight Center) Model PDRE (Pulse Detonation Rocket Engine) G-2) has been developed for the purpose of examining integrated propulsion and magnetohydrodynamic power generation applications. The engine is based on a rectangular cross-section tube coupled to a converging-diverging nozzle, which is in turn attached to a segmented Faraday channel. As part of the shakedown testing activity, the pressure wave was interrogated along the length of the engine while running on hydrogen/oxygen propellants. Rapid transition to detonation wave propagation was insured through the use of a short Schelkin spiral near the head of the engine. The measured detonation wave velocities were in excess of 2500 m/s in agreement with the theoretical C-J velocity. The engine was first tested in a straight tube configuration without a nozzle, and the time resolved thrust was measured simultaneously with the head-end pressure. Similar measurements were made with the converging-diverging nozzle attached. The time correlation of the thrust and head-end pressure data was found to be excellent. The major purpose of the converging-diverging nozzle was to configure the engine for driving an MHD generator for the direct production of electrical power. Additional tests were therefore necessary in which seed (cesium-hydroxide dissolved in methanol) was directly injected into the engine as a spray. The exhaust plume was then interrogated with a microwave interferometer in an attempt to characterize the plasma conditions, and emission spectroscopy measurements were also acquired. Data reduction efforts indicate that the plasma exhaust is very highly ionized, although there is some uncertainty at this time as to the relative abundance of negative OH ions. The emission spectroscopy data provided some indication of the species in the exhaust as well as a measurement of temperature. A 24-electrode-pair segmented Faraday channel and 0.6 Tesla permanent

  11. MHD equilibria with diamagnetic effects

    Science.gov (United States)

    Tessarotto, M.; Zorat, R.; Johnson, J. L.; White, R. B.

    1997-11-01

    An outstanding issue in magnetic confinement is the establishment of MHD equilibria with enhanced flow shear profiles for which turbulence (and transport) may be locally effectively suppressed or at least substantially reduced with respect to standard weak turbulence models. Strong flows develop in the presence of equilibrium E× B-drifts produced by a strong radial electric field, as well as due to diamagnetic contributions produced by steep equilibrium radial profiles of number density, temperature and the flow velocity itself. In the framework of a kinetic description, this generally requires the construction of guiding-center variables correct to second order in the relevant expansion parameter. For this purpose, the Lagrangian approach developed recently by Tessarotto et al. [1] is adopted. In this paper the conditions of existence of such equilibria are analyzed and their basic physical properties are investigated in detail. 1 - M. Pozzo, M. Tessarotto and R. Zorat, in Theory of fusion Plasmas, E.Sindoni et al. eds. (Societá Italiana di Fisica, Editrice Compositori, Bologna, 1996), p.295.

  12. Mythic Evolution of "The New Frontier" in Mass Mediated Rhetoric.

    Science.gov (United States)

    Rushing, Janice Hocker

    1986-01-01

    Combines "rhetorical narration" with K. Burke's dramatistic pentad to argue that definitional cultural myths are rhetorically meaningful in relation to social consciousness if both evolved teleologically. Delineates two phases in America's frontier myth associated with recent space fiction films' representation of a pentadic term's…

  13. Acceleration of the OpenFOAM-based MHD solver using graphics processing units

    Energy Technology Data Exchange (ETDEWEB)

    He, Qingyun; Chen, Hongli, E-mail: hlchen1@ustc.edu.cn; Feng, Jingchao

    2015-12-15

    Highlights: • A 3D PISO-MHD was implemented on Kepler-class graphics processing units (GPUs) using CUDA technology. • A consistent and conservative scheme is used in the code which was validated by three basic benchmarks in a rectangular and round ducts. • Parallelized of CPU and GPU acceleration were compared relating to single core CPU in MHD problems and non-MHD problems. • Different preconditions for solving MHD solver were compared and the results showed that AMG method is better for calculations. - Abstract: The pressure-implicit with splitting of operators (PISO) magnetohydrodynamics MHD solver of the couple of Navier–Stokes equations and Maxwell equations was implemented on Kepler-class graphics processing units (GPUs) using the CUDA technology. The solver is developed on open source code OpenFOAM based on consistent and conservative scheme which is suitable for simulating MHD flow under strong magnetic field in fusion liquid metal blanket with structured or unstructured mesh. We verified the validity of the implementation on several standard cases including the benchmark I of Shercliff and Hunt's cases, benchmark II of fully developed circular pipe MHD flow cases and benchmark III of KIT experimental case. Computational performance of the GPU implementation was examined by comparing its double precision run times with those of essentially the same algorithms and meshes. The resulted showed that a GPU (GTX 770) can outperform a server-class 4-core, 8-thread CPU (Intel Core i7-4770k) by a factor of 2 at least.

  14. Smoothed MHD equations for numerical simulations of ideal quasi-neutral gas dynamic flows

    Science.gov (United States)

    Popov, Mikhail V.; Elizarova, Tatiana G.

    2015-11-01

    We introduce a mathematical model and related numerical method for numerical modeling of ideal magnetohydrodynamic (MHD) gas flows as an extension of previously known quasi-gasdynamic (QGD) equations. This approach is based on smoothing, or averaging of the original MHD equation system over a small time interval that leads to a new equation system, named quasi-MHD, or QMHD system. The QMHD equations are closely related to the original MHD system except for additional strongly non-linear dissipative τ-terms with a small parameter τ as a factor. The τ-terms depend on the solution itself and decrease in regions with the small space gradients of the solution. In this sense the QMHD system could be regarded as an approach with adaptive artificial dissipation. The QMHD is a generalization of regularized (or quasi-) gas dynamic equation system suggested in last three decades. In the QMHD numerical method the evolution of all physical variables is presented in a non-split divergence form. Divergence-free evolution of the magnetic field provides by using a constrained transport method based on Faraday's law of induction. Accuracy and convergence of the QMHD method is verified on a wide set of standard MHD tests including the 3D Orszag-Tang vortex flow.

  15. Numerical study of MHD supersonic flow control

    Science.gov (United States)

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

    2017-11-01

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

  16. Frontier Scientists use Modern Media

    Science.gov (United States)

    O'connell, E. A.

    2013-12-01

    Engaging Americans and the international community in the excitement and value of Alaskan Arctic discovery is the goal of Frontier Scientists. With a changing climate, resources of polar regions are being eyed by many nations. Frontier Scientists brings the stories of field scientists in the Far North to the public. With a website, an app, short videos, and social media channels; FS is a model for making connections between the public and field scientists. FS will demonstrate how academia, web content, online communities, evaluation and marketing are brought together in a 21st century multi-media platform, how scientists can maintain their integrity while engaging in outreach, and how new forms of media such as short videos can entertain as well as inspire.

  17. Euler potentials for the MHD Kamchatnov-Hopf soliton solution

    NARCIS (Netherlands)

    Semenov, VS; Korovinski, DB; Biernat, HK

    2002-01-01

    In the MHD description of plasma phenomena the concept of magnetic helicity turns out to be very useful. We present here an example of introducing Euler potentials into a topological MHD soliton which has non-trivial helicity. The MHD soliton solution (Kamchatnov, 1982) is based on the Hopf

  18. US Frontiers of Engineering Symposia

    Science.gov (United States)

    2015-02-01

    familiar with the program, FOE has expanded to include bilateral meetings with Germany, Japan , India, China, and the EU. The US Frontiers meetings...at the Hotel du Pont in Wilmington, Delaware. Dr. Kristi Anseth, Distinguished Professor of Chemical and Biological Engineering and HHMI Assistant...with 48 from academe, 48 from industry, and 12 from government, and the topics were Co- Robotics , Battery Anxiety (New Materials for Batteries

  19. Analytic MHD Theory for Earth's Bow Shock at Low Mach Numbers

    Science.gov (United States)

    Grabbe, Crockett L.; Cairns, Iver H.

    1995-01-01

    A previous MHD theory for the density jump at the Earth's bow shock, which assumed the Alfven M(A) and sonic M(s) Mach numbers are both much greater than 1, is reanalyzed and generalized. It is shown that the MHD jump equation can be analytically solved much more directly using perturbation theory, with the ordering determined by M(A) and M(s), and that the first-order perturbation solution is identical to the solution found in the earlier theory. The second-order perturbation solution is calculated, whereas the earlier approach cannot be used to obtain it. The second-order terms generally are important over most of the range of M(A) and M(s) in the solar wind when the angle theta between the normal to the bow shock and magnetic field is not close to 0 deg or 180 deg (the solutions are symmetric about 90 deg). This new perturbation solution is generally accurate under most solar wind conditions at 1 AU, with the exception of low Mach numbers when theta is close to 90 deg. In this exceptional case the new solution does not improve on the first-order solutions obtained earlier, and the predicted density ratio can vary by 10-20% from the exact numerical MHD solutions. For theta approx. = 90 deg another perturbation solution is derived that predicts the density ratio much more accurately. This second solution is typically accurate for quasi-perpendicular conditions. Taken together, these two analytical solutions are generally accurate for the Earth's bow shock, except in the rare circumstance that M(A) is less than or = 2. MHD and gasdynamic simulations have produced empirical models in which the shock's standoff distance a(s) is linearly related to the density jump ratio X at the subsolar point. Using an empirical relationship between a(s) and X obtained from MHD simulations, a(s) values predicted using the MHD solutions for X are compared with the predictions of phenomenological models commonly used for modeling observational data, and with the predictions of a

  20. Frontier petroleum basins of Colombia

    Energy Technology Data Exchange (ETDEWEB)

    Keith, J.F. Jr.; Perez, V.E.

    1989-03-01

    The frontier basins of Colombia with hydrocarbon potential are numerous, have varying geological histories, and are in different stages of exploration development. In this paper, sedimentary or structural basins are classified as frontier petroleum basins if commercial discoveries of hydrocarbons are lacking, if the basin has not attained a high degree of exploration development, or if a new play concept has been perceived or developed for a portion of a mature exploration basin. Using these criteria for classification, the authors discuss the Cauca-Patia Choco-Pacifico, and Lower Magdalena basin complexes; the Cordillera Oriental foreland basin; and the Cesar-Rancheria, Sabana, and Amazonas basins. A comprehensive geological and structural setting of each of these frontier basins will be presented. The depositional and tectonic evolution of the basins will be highlighted, and the play concepts for each will be inventoried, catalogued, and categorized as to whether they are theoretical or established. The discussion of the available plays in each of these basins will include the main play concept elements of reservoirs traps, seals, source rocks, maturation, and timing. When detailed data permit, the reservoir and trap geometry will be presented.

  1. Bioactive glasses: Frontiers and challenges

    Directory of Open Access Journals (Sweden)

    Larry L. Hench

    2015-11-01

    Full Text Available Bioactive glasses were discovered in 1969 and provided for the first time an alternative to nearly inert implant materials. Bioglass formed a rapid, strong and stable bond with host tissues. This article examines the frontiers of research crossed to achieve clinical use of bioactive glasses and glass-ceramics. In the 1980’s it was discovered that bioactive glasses could be used in particulate form to stimulate osteogenesis, which thereby led to the concept of regeneration of tissues. Later, it was discovered that the dissolution ions from the glasses behaved like growth factors, providing signals to the cells. This article summarizes the frontiers of knowledge crossed during four eras of development of bioactive glasses that have led from concept of bioactivity to widespread clinical and commercial use, with emphasis on the first composition, 45S5 Bioglass®. The four eras are: a discovery; b clinical application; c tissue regeneration; and d innovation. Questions still to be answered for the fourth era are included to stimulate innovation in the field and exploration of new frontiers that can be the basis for a general theory of bioactive stimulation of regeneration of tissues and application to numerous clinical needs.

  2. MHD heat and seed recovery technology project. Ninth quarterly report, January-March 1980

    Energy Technology Data Exchange (ETDEWEB)

    Petrick, Michael; Johnson, Terry R.

    1980-05-01

    The MHD Heat and Seed Recovery Technology Project at Argonne National Laboratory is obtaining information for the design and operation of the steam plant downstream of the MHD channel-diffuser, and of the seed regeneration process. The project goal is to supply the engineering data required in the design of components for prototype and demonstration MHD facilities. The primary effort of the HSR Technology Project at Argonne is directed toward experimental investigations of critical problem areas, such as (1) NO/sub x/ behavior in the radiant boiler and secondary combustor; (2) radiant boiler design to meet the multiple requirements of steam generation, NO/sub x/ decomposition, and seed-slag separation; (3) effects of solid or liquid seed deposits on heat transfer and gas flow in the steam and air heaters; (4) formation, growth, and deposition of seed-slag particles; and (5) character of the combustion gas effluents. These investigations are performed primarily in a 2-MW test facility, Argonne MHD Process Engineering Laboratory (AMPEL). Other project activities are related to studies of the thermochemistry of the seed-slag combustion gas system, identification of ceramic and metallic materials for service in the MHD-steam plant, and evaluation of seed regeneration processes. Progress is described.

  3. Porting a Hall MHD Code to a Graphic Processing Unit

    Science.gov (United States)

    Dorelli, John C.

    2011-01-01

    We present our experience porting a Hall MHD code to a Graphics Processing Unit (GPU). The code is a 2nd order accurate MUSCL-Hancock scheme which makes use of an HLL Riemann solver to compute numerical fluxes and second-order finite differences to compute the Hall contribution to the electric field. The divergence of the magnetic field is controlled with Dedner?s hyperbolic divergence cleaning method. Preliminary benchmark tests indicate a speedup (relative to a single Nehalem core) of 58x for a double precision calculation. We discuss scaling issues which arise when distributing work across multiple GPUs in a CPU-GPU cluster.

  4. MHD equilibrium and stability in heliotron plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ichiguchi, Katsuji [National Inst. for Fusion Science, Toki, Gifu (Japan)

    1999-09-01

    Recent topics in the theoretical magnetohydrodynamic (MHD) analysis in the heliotron configuration are overviewed. Particularly, properties of three-dimensional equilibria, stability boundary of the interchange mode, effects of the net toroidal current including the bootstrap current and the ballooning mode stability are focused. (author)

  5. Hodograph method in MHD orthogonal fluid flows

    Directory of Open Access Journals (Sweden)

    P. V. Nguyen

    1992-01-01

    Full Text Available Equations for steady plane MHD orthogonal flows of a viscous incompressible fluid of finite electrical conductivity are recast in the hodograph plane by using the Legendre transform function of the streamfunction. Three examples are studied to illustrate the developed theory. Solutions and geometries for these examples are determined.

  6. MHD Ballooning Instability in the Plasma Sheet

    Energy Technology Data Exchange (ETDEWEB)

    C.Z. Cheng; S. Zaharia

    2003-10-20

    Based on the ideal-MHD model the stability of ballooning modes is investigated by employing realistic 3D magnetospheric equilibria, in particular for the substorm growth phase. Previous MHD ballooning stability calculations making use of approximations on the plasma compressibility can give rise to erroneous conclusions. Our results show that without making approximations on the plasma compressibility the MHD ballooning modes are unstable for the entire plasma sheet where beta (sub)eq is greater than or equal to 1, and the most unstable modes are located in the strong cross-tail current sheet region in the near-Earth plasma sheet, which maps to the initial brightening location of the breakup arc in the ionosphere. However, the MHD beq threshold is too low in comparison with observations by AMPTE/CCE at X = -(8 - 9)R(sub)E, which show that a low-frequency instability is excited only when beq increases over 50. The difficulty is mitigated by considering the kinetic effects of ion gyrorad ii and trapped electron dynamics, which can greatly increase the stabilizing effects of field line tension and thus enhance the beta(sub)eq threshold [Cheng and Lui, 1998]. The consequence is to reduce the equatorial region of the unstable ballooning modes to the strong cross-tail current sheet region where the free energy associated with the plasma pressure gradient and magnetic field curvature is maximum.

  7. Compressible MHD Turbulence in the Slow Solar Wind: Energy Transfer Rate

    Science.gov (United States)

    Sahraoui, F.; Andres, N.; Hadid, L.; Galtier, S.; Dmitruk, P.; Mininni, P. D.

    2016-12-01

    The role of compressible fluctuations in the MHD turbulence is investigated using direct numerical simulations and in-situ spacecraft in the solar wind. A focus is put on verifying the exact third-order law derived for compressible isothermal turbulence by Banerjee and Galtier, 2013. The numerical simulations use a 3D compressible MHD code in the isothermal limit ( =1) with low sonic Mach numbers (Ms<1). The main goal is to evaluate the relative importance of the new flux and source terms involved in the derived law. Direct comparison with spacecraft observations from the Themis spacecraft in the fast and slow solar wind will be made.

  8. Review and assessments of potential environmental, health and safety impacts of MHD technology. Final draft

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-01

    The purpose of this document is to develop an environmental, health and safety (EH and S) assessment and begin a site - specific assessment of these and socio - economic impacts for the magnetohydrodynamics program of the United States Department of Energy. This assessment includes detailed scientific and technical information on the specific EH and S issues mentioned in the MHD Environmental Development Plan. A review of current literature on impact-related subjects is also included. This document addresses the coal-fired, open-cycle MHD technology and reviews and assesses potential EH and S impacts resulting from operation of commercially-installed technology.

  9. Fitting of full Cobb-Douglas and full VRTS cost frontiers by solving goal programming problem

    Science.gov (United States)

    Venkateswarlu, B.; Mahaboob, B.; Subbarami Reddy, C.; Madhusudhana Rao, B.

    2017-11-01

    The present research article first defines two popular production functions viz, Cobb-Douglas and VRTS production frontiers and their dual cost functions and then derives their cost limited maximal outputs. This paper tells us that the cost limited maximal output is cost efficient. Here the one side goal programming problem is proposed by which the full Cobb-Douglas cost frontier, full VRTS frontier can be fitted. This paper includes the framing of goal programming by which stochastic cost frontier and stochastic VRTS frontiers are fitted. Hasan et al. [1] used a parameter approach Stochastic Frontier Approach (SFA) to examine the technical efficiency of the Malaysian domestic banks listed in the Kuala Lumpur stock Exchange (KLSE) market over the period 2005-2010. AshkanHassani [2] exposed Cobb-Douglas Production Functions application in construction schedule crashing and project risk analysis related to the duration of construction projects. Nan Jiang [3] applied Stochastic Frontier analysis to a panel of New Zealand dairy forms in 1998/99-2006/2007.

  10. Frontiers in mathematical biology

    CERN Document Server

    1994-01-01

    Volume 100, which is the final volume of the LNBM series serves to commemorate the acievements in two decades of this influential collection of books in mathematical biology. The contributions, by the leading mathematical biologists, survey the state of the art in the subject, and offer speculative, philosophical and critical analyses of the key issues confronting the field. The papers address fundamental issues in cell and molecular biology, organismal biology, evolutionary biology, population ecology, community and ecosystem ecology, and applied biology, plus the explicit and implicit mathematical challenges. Cross-cuttting issues involve the problem of variation among units in nonlinear systems, and the related problems of the interactions among phenomena across scales of space, time and organizational complexity.

  11. New frontiers in PDF determination

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Parton Distribution Functions (PDFs) are a crucial input at the LHC, their uncertainty often being the limiting factor in the accuracy of theoretical predictions. At the same time the LHC is delivering a number of precise measurements that have the potential to greatly constrain these functions. I will give an overview on the theory behind and on the state of the art of PDF determination. I will then mention the new theoretical and methodological challenges in modern PDF fits and explore the precision frontiers opened by the accuracy of the LHC data.

  12. Fundamental Physics at the Intensity Frontier

    CERN Document Server

    Hewett, J.L.; Brock, R.; Butler, J.N.; Casey, B.C.K.; Collar, J.; de Gouvea, A.; Essig, R.; Grossman, Y.; Haxton, W.; Jaros, J.A.; Jung, C.K.; Lu, Z.T.; Pitts, K.; Ligeti, Z.; Patterson, J.R.; Ramsey-Musolf, M.; Ritchie, J.L.; Roodman, A.; Scholberg, K.; Wagner, C.E.M.; Zeller, G.P.; Aefsky, S.; Afanasev, A.; Agashe, K.; Albright, C.; Alonso, J.; Ankenbrandt, C.; Aoki, M.; Arguelles, C.A.; Arkani-Hamed, N.; Armendariz, J.R.; Armendariz-Picon, C.; Arrieta Diaz, E.; Asaadi, J.; Asner, D.M.; Babu, K.S.; Bailey, K.; Baker, O.; Balantekin, B.; Baller, B.; Bass, M.; Batell, B.; Beacham, J.; Behr, J.; Berger, N.; Bergevin, M.; Berman, E.; Bernstein, R.; Bevan, A.J.; Bishai, M.; Blanke, M.; Blessing, S.; Blondel, A.; Blum, T.; Bock, G.; Bodek, A.; Bonvicini, G.; Bossi, F.; Boyce, J.; Breedon, R.; Breidenbach, M.; Brice, S.J.; Briere, R.A.; Brodsky, S.; Bromberg, C.; Bross, A.; Browder, T.E.; Bryman, D.A.; Buckley, M.; Burnstein, R.; Caden, E.; Campana, P.; Carlini, R.; Carosi, G.; Castromonte, C.; Cenci, R.; Chakaberia, I.; Chen, Mu-Chun; Cheng, C.H.; Choudhary, B.; Christ, N.H.; Christensen, E.; Christy, M.E.; Chupp, T.E.; Church, E.; Cline, D.B.; Coan, T.E.; Coloma, P.; Comfort, J.; Coney, L.; Cooper, J.; Cooper, R.J.; Cowan, R.; Cowen, D.F.; Cronin-Hennessy, D.; Datta, A.; Davies, G.S.; Demarteau, M.; DeMille, D.P.; Denig, A.; Dermisek, R.; Deshpande, A.; Dewey, M.S.; Dharmapalan, R.; Dhooghe, J.; Dietrich, M.R.; Diwan, M.; Djurcic, Z.; Dobbs, S.; Duraisamy, M.; Dutta, B.; Duyang, H.; Dwyer, D.A.; Eads, M.; Echenard, B.; Elliott, S.R.; Escobar, C.; Fajans, J.; Farooq, S.; Faroughy, C.; Fast, J.E.; Feinberg, B.; Felde, J.; Feldman, G.; Fierlinger, P.; Fileviez Perez, P.; Filippone, B.; Fisher, P.; Flemming, B.T.; Flood, K.T.; Forty, R.; Frank, M.J.; Freyberger, A.; Friedland, A.; Gandhi, R.; Ganezer, K.S.; Garcia, A.; Garcia, F.G.; Gardner, S.; Garrison, L.; Gasparian, A.; Geer, S.; Gehman, V.M.; Gershon, T.; Gilchriese, M.; Ginsberg, C.; Gogoladze, I.; Gonderinger, M.; Goodman, M.; Gould, H.; Graham, M.; Graham, P.W.; Gran, R.; Grange, J.; Gratta, G.; Green, J.P.; Greenlee, H.; Group, R.C.; Guardincerri, E.; Gudkov, V.; Guenette, R.; Haas, A.; Hahn, A.; Han, T.; Handler, T.; Hardy, J.C.; Harnik, R.; Harris, D.A.; Harris, F.A.; Harris, P.G.; Hartnett, J.; He, B.; Heckel, B.R.; Heeger, K.M.; Henderson, S.; Hertzog, D.; Hill, R.; Hinds, E.A.; Hitlin, D.G.; Holt, R.J.; Holtkamp, N.; Horton-Smith, G.; Huber, P.; Huelsnitz, W.; Imber, J.; Irastorza, I.; Jaeckel, J.; Jaegle, I.; James, C.; Jawahery, A.; Jensen, D.; Jessop, C.P.; Jones, B.; Jostlein, H.; Junk, T.; Kagan, A.L.; Kalita, M.; Kamyshkov, Y.; Kaplan, D.M.; Karagiorgi, G.; Karle, A.; Katori, T.; Kayser, B.; Kephart, R.; Kettell, S.; Kim, Y.K.; Kirby, M.; Kirch, K.; Klein, J.; Kneller, J.; Kobach, A.; Kohl, M.; Kopp, J.; Kordosky, M.; Korsch, W.; Kourbanis, I.; Krisch, A.D.; Krizan, P.; Kronfeld, A.S.; Kulkarni, S.; Kumar, K.S.; Kuno, Y.; Kutter, T.; Lachenmaier, T.; Lamm, M.; Lancaster, J.; Lancaster, M.; Lane, C.; Lang, K.; Langacker, P.; Lazarevic, S.; Le, T.; Lee, K.; Lesko, K.T.; Li, Y.; Lindgren, M.; Lindner, A.; Link, J.; Lissauer, D.; Littenberg, L.S.; Littlejohn, B.; Liu, C.Y.; Loinaz, W.; Lorenzon, W.; Louis, W.C.; Lozier, J.; Ludovici, L.; Lueking, L.; Lunardini, C.; MacFarlane, D.B.; Machado, P.A.N.; Mackenzie, P.B.; Maloney, J.; Marciano, W.J.; Marsh, W.; Marshak, M.; Martin, J.W.; Mauger, C.; McFarland, K.S.; McGrew, C.; McLaughlin, G.; McKeen, D.; McKeown, R.; Meadows, B.T.; Mehdiyev, R.; Melconian, D.; Merkel, H.; Messier, M.; Miller, J.P.; Mills, G.; Minamisono, U.K.; Mishra, S.R.; Mocioiu, I.; Sher, S.Moed; Mohapatra, R.N.; Monreal, B.; Moore, C.D.; Morfin, J.G.; Mousseau, J.; Moustakas, L.A.; Mueller, G.; Mueller, P.; Muether, M.; Mumm, H.P.; Munger, C.; Murayama, H.; Nath, P.; Naviliat-Cuncin, O.; Nelson, J.K.; Neuffer, D.; Nico, J.S.; Norman, A.; Nygren, D.; Obayashi, Y.; O'Connor, T.P.; Okada, Y.; Olsen, J.; Orozco, L.; Orrell, J.L.; Osta, J.; Pahlka, B.; Paley, J.; Papadimitriou, V.; Papucci, M.; Parke, S.; Parker, R.H.; Parsa, Z.; Partyka, K.; Patch, A.; Pati, J.C.; Patterson, R.B.; Pavlovic, Z.; Paz, Gil; Perdue, G.N.; Perevalov, D.; Perez, G.; Petti, R.; Pettus, W.; Piepke, A.; Pivovaroff, M.; Plunkett, R.; Polly, C.C.; Pospelov, M.; Povey, R.; Prakesh, A.; Purohit, M.V.; Raby, S.; Raaf, J.L.; Rajendran, R.; Rajendran, S.; Rameika, G.; Ramsey, R.; Rashed, A.; Ratcliff, B.N.; Rebel, B.; Redondo, J.; Reimer, P.; Reitzner, D.; Ringer, F.; Ringwald, A.; Riordan, S.; Roberts, B.L.; Roberts, D.A.; Robertson, R.; Robicheaux, F.; Rominsky, M.; Roser, R.; Rosner, J.L.; Rott, C.; Rubin, P.; Saito, N.; Sanchez, M.; Sarkar, S.; Schellman, H.; Schmidt, B.; Schmitt, M.; Schmitz, D.W.; Schneps, J.; Schopper, A.; Schuster, P.; Schwartz, A.J.; Schwarz, M.; Seeman, J.; Semertzidis, Y.K.; Seth, K.K.; Shafi, Q.; Shanahan, P.; Sharma, R.; Sharpe, S.R.; Shiozawa, M.; Shiltsev, V.; Sigurdson, K.; Sikivie, P.; Singh, J.; Sivers, D.; Skwarnicki, T.; Smith, N.; Sobczyk, J.; Sobel, H.; Soderberg, M.; Song, Y.H.; Soni, A.; Souder, P.; Sousa, A.; Spitz, J.; Stancari, M.; Stavenga, G.C.; Steffen, J.H.; Stepanyan, S.; Stoeckinger, D.; Stone, S.; Strait, J.; Strassler, M.; Sulai, I.A.; Sundrum, R.; Svoboda, R.; Szczerbinska, B.; Szelc, A.; Takeuchi, T.; Tanedo, P.; Taneja, S.; Tang, J.; Tanner, D.B.; Tayloe, R.; Taylor, I.; Thomas, J.; Thorn, C.; Tian, X.; Tice, B.G.; Tobar, M.; Tolich, N.; Toro, N.; Towner, I.S.; Tsai, Y.; Tschirhart, R.; Tunnell, C.D.; Tzanov, M.; Upadhye, A.; Urheim, J.; Vahsen, S.; Vainshtein, A.; Valencia, E.; Van de Water, R.G.; Van de Water, R.S.; Velasco, M.; Vogel, J.; Vogel, P.; Vogelsang, W.; Wah, Y.W.; Walker, D.; Weiner, N.; Weltman, A.; Wendell, R.; Wester, W.; Wetstein, M.; White, C.; Whitehead, L.; Whitmore, J.; Widmann, E.; Wiedemann, G.; Wilkerson, J.; Wilkinson, G.; Wilson, P.; Wilson, R.J.; Winter, W.; Wise, M.B.; Wodin, J.; Wojcicki, S.; Wojtsekhowski, B.; Wongjirad, T.; Worcester, E.; Wurtele, J.; Xin, T.; Xu, J.; Yamanaka, T.; Yamazaki, Y.; Yavin, I.; Yeck, J.; Yeh, M.; Yokoyama, M.; Yoo, J.; Young, A.; Zimmerman, E.; Zioutas, K.; Zisman, M.; Zupan, J.; Zwaska, R.; Intensity Frontier Workshop

    2012-01-01

    The Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. Science opportunities at the intensity frontier are identified and described in the areas of heavy quarks, charged leptons, neutrinos, proton decay, new light weakly-coupled particles, and nucleons, nuclei, and atoms.

  13. Southwest, Frontier planes clip wings in Phoenix

    National Research Council Canada - National Science Library

    Ben Mutzabaugh

    2017-01-01

    ... reports did not specify which one. Video from ABC 15 of Phoenix showed damage to the wing tip of the Southwest plane. A separate image tweeted by CBS 5 of Phoenix indicated that the wing of the Frontier aircraft also was damaged. The Frontier flight was bound for Denver, and the carrier put passengers on a replacement aircraft. Passengers on Southwest's ...

  14. Frontiers of interfacial water research :workshop report.

    Energy Technology Data Exchange (ETDEWEB)

    Cygan, Randall Timothy; Greathouse, Jeffery A.

    2005-10-01

    Water is the critical natural resource of the new century. Significant improvements in traditional water treatment processes require novel approaches based on a fundamental understanding of nanoscale and atomic interactions at interfaces between aqueous solution and materials. To better understand these critical issues and to promote an open dialog among leading international experts in water-related specialties, Sandia National Laboratories sponsored a workshop on April 24-26, 2005 in Santa Fe, New Mexico. The ''Frontiers of Interfacial Water Research Workshop'' provided attendees with a critical review of water technologies and emphasized the new advances in surface and interfacial microscopy, spectroscopy, diffraction, and computer simulation needed for the development of new materials for water treatment.

  15. Materials Frontiers to Empower Quantum Computing

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Antoinette Jane [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sarrao, John Louis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Richardson, Christopher [Laboratory for Physical Sciences, College Park, MD (United States)

    2015-06-11

    This is an exciting time at the nexus of quantum computing and materials research. The materials frontiers described in this report represent a significant advance in electronic materials and our understanding of the interactions between the local material and a manufactured quantum state. Simultaneously, directed efforts to solve materials issues related to quantum computing provide an opportunity to control and probe the fundamental arrangement of matter that will impact all electronic materials. An opportunity exists to extend our understanding of materials functionality from electronic-grade to quantum-grade by achieving a predictive understanding of noise and decoherence in qubits and their origins in materials defects and environmental coupling. Realizing this vision systematically and predictively will be transformative for quantum computing and will represent a qualitative step forward in materials prediction and control.

  16. Frontiers in nuclear astrophysics

    Science.gov (United States)

    Bertulani, C. A.; Kajino, T.

    2016-07-01

    The synthesis of nuclei in diverse cosmic scenarios is reviewed, with a summary of the basic concepts involved before a discussion of the current status in each case is made. We review the physics of the early universe, the proton to neutron ratio influence in the observed helium abundance, reaction networks, the formation of elements up to beryllium, the inhomogeneous Big Bang model, and the Big Bang nucleosynthesis constraints on cosmological models. Attention is paid to element production in stars, together with the details of the pp chain, the pp reaction, 3He formation and destruction, electron capture on 7Be, the importance of 8B formation and its relation to solar neutrinos, and neutrino oscillations. Nucleosynthesis in massive stars is also reviewed, with focus on the CNO cycle and its hot companion cycle, the rp-process, triple- α capture, and red giants and AGB stars. The stellar burning of carbon, neon, oxygen, and silicon is presented in a separate section, as well as the slow and rapid nucleon capture processes and the importance of medium modifications due to electrons also for pycnonuclear reactions. The nucleosynthesis in cataclysmic events such as in novae, X-ray bursters and in core-collapse supernovae, the role of neutrinos, and the supernova radioactivity and light-curve is further discussed, as well as the structure of neutron stars and its equation of state. A brief review of the element composition found in cosmic rays is made in the end.

  17. The Frontier Fields: Survey Design and Initial Results

    Energy Technology Data Exchange (ETDEWEB)

    Lotz, J. M.; Koekemoer, A.; Grogin, N.; Mack, J.; Anderson, J.; Avila, R.; Barker, E. A.; Borncamp, D.; Durbin, M.; Gunning, H.; Hilbert, B.; Jenkner, H.; Khandrika, H.; Levay, Z.; Lucas, R. A.; MacKenty, J.; Ogaz, S. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Coe, D.; Capak, P.; Brammer, G., E-mail: lotz@stsci.edu [European Space Agency/Space Telescope Science Institute, 3700 Sam Martin Drive, Baltimore, MD 21218 (United States); and others

    2017-03-01

    What are the faintest distant galaxies we can see with the Hubble Space Telescope ( HST ) now, before the launch of the James Webb Space Telescope ? This is the challenge taken up by the Frontier Fields, a Director’s discretionary time campaign with HST and the Spitzer Space Telescope to see deeper into the universe than ever before. The Frontier Fields combines the power of HST and Spitzer with the natural gravitational telescopes of massive high-magnification clusters of galaxies to produce the deepest observations of clusters and their lensed galaxies ever obtained. Six clusters—Abell 2744, MACSJ0416.1-2403, MACSJ0717.5+3745, MACSJ1149.5+2223, Abell S1063, and Abell 370—have been targeted by the HST ACS/WFC and WFC3/IR cameras with coordinated parallel fields for over 840 HST orbits. The parallel fields are the second-deepest observations thus far by HST with 5 σ point-source depths of ∼29th ABmag. Galaxies behind the clusters experience typical magnification factors of a few, with small regions magnified by factors of 10–100. Therefore, the Frontier Field cluster HST images achieve intrinsic depths of ∼30–33 mag over very small volumes. Spitzer has obtained over 1000 hr of Director’s discretionary imaging of the Frontier Field cluster and parallels in IRAC 3.6 and 4.5 μ m bands to 5 σ point-source depths of ∼26.5, 26.0 ABmag. We demonstrate the exceptional sensitivity of the HST Frontier Field images to faint high-redshift galaxies, and review the initial results related to the primary science goals.

  18. The Frontier Fields: Survey Design and Initial Results

    Science.gov (United States)

    Lotz, J. M.; Koekemoer, A.; Coe, D.; Grogin, N.; Capak, P.; Mack, J.; Anderson, J.; Avila, R.; Barker, E. A.; Borncamp, D.; Brammer, G.; Durbin, M.; Gunning, H.; Hilbert, B.; Jenkner, H.; Khandrika, H.; Levay, Z.; Lucas, R. A.; MacKenty, J.; Ogaz, S.; Porterfield, B.; Reid, N.; Robberto, M.; Royle, P.; Smith, L. J.; Storrie-Lombardi, L. J.; Sunnquist, B.; Surace, J.; Taylor, D. C.; Williams, R.; Bullock, J.; Dickinson, M.; Finkelstein, S.; Natarajan, P.; Richard, J.; Robertson, B.; Tumlinson, J.; Zitrin, A.; Flanagan, K.; Sembach, K.; Soifer, B. T.; Mountain, M.

    2017-03-01

    What are the faintest distant galaxies we can see with the Hubble Space Telescope (HST) now, before the launch of the James Webb Space Telescope? This is the challenge taken up by the Frontier Fields, a Director’s discretionary time campaign with HST and the Spitzer Space Telescope to see deeper into the universe than ever before. The Frontier Fields combines the power of HST and Spitzer with the natural gravitational telescopes of massive high-magnification clusters of galaxies to produce the deepest observations of clusters and their lensed galaxies ever obtained. Six clusters—Abell 2744, MACSJ0416.1-2403, MACSJ0717.5+3745, MACSJ1149.5+2223, Abell S1063, and Abell 370—have been targeted by the HST ACS/WFC and WFC3/IR cameras with coordinated parallel fields for over 840 HST orbits. The parallel fields are the second-deepest observations thus far by HST with 5σ point-source depths of ˜29th ABmag. Galaxies behind the clusters experience typical magnification factors of a few, with small regions magnified by factors of 10-100. Therefore, the Frontier Field cluster HST images achieve intrinsic depths of ˜30-33 mag over very small volumes. Spitzer has obtained over 1000 hr of Director’s discretionary imaging of the Frontier Field cluster and parallels in IRAC 3.6 and 4.5 μm bands to 5σ point-source depths of ˜26.5, 26.0 ABmag. We demonstrate the exceptional sensitivity of the HST Frontier Field images to faint high-redshift galaxies, and review the initial results related to the primary science goals.

  19. [Brazilian colonization in the Paraguayan agricultural frontier].

    Science.gov (United States)

    Neupert, R F

    1991-04-01

    Grande do Sul. Many were relatively small producers who were attracted to the Alto Parana region of Paraguay near the Brazilian border by its geographic proximity, extensive availability of land at low prices, and favorable credit and tax policies. Many small proprietors from Brazil were able to buy extensive tracts in Paraguay and to develop an economy based on cultivation of export crops on small and medium sized holdings. A serious and efficient plan for financial aid, together with technical assistance and intensive training programs, could have placed Paraguayan cultivators in a position similar to that of the Brazilians. Paraguayan colonists in the frontier areas could then have progressed rapidly beyond their current state of subsistence or semisubsistence agriculture to the kind of entrepreneurial agriculture practiced by the Brazilians.

  20. Effect of Hartmann layer resolution for MHD flow in a straight ...

    Indian Academy of Sciences (India)

    for complex geometry MHD simulation. Keywords. Magnetohydrodynamics; Hartmann number; test blanket module. 1. Introduction. Magnetohydrodynamics studies the flow of electrically conducting, non-magnetic fluids sub- jected to an external magnetic field (Muller & Buhler 2001). The relative motion of such a fluid.

  1. The frontier beneath our feet

    Science.gov (United States)

    Grant, Gordon E.; Dietrich, William E.

    2017-04-01

    Following the simple question as to where water goes when it rains leads to one of the most exciting frontiers in earth science: the critical zone—Earth's dynamic skin. The critical zone extends from the top of the vegetation canopy through the soil and down to fresh bedrock and the bottom of the groundwater. Only recently recognized as a distinct zone, it is challenging to study because it is hard to observe directly, and varies widely across biogeoclimatic regions. Yet new ideas, instruments, and observations are revealing surprising and sometimes paradoxical insights, underscoring the value of field campaigns and long-term observatories. These insights bear directly on some of the most pressing societal problems today: maintaining healthy forests, sustaining streamflow during droughts, and restoring productive terrestrial and aquatic ecosystems. The critical zone is critical because it supports all terrestrial life; it is the nexus where water and carbon is cycled, vegetation (hence food) grows, soil develops, landscapes evolve, and we live. No other frontier is so close to home.

  2. Intracluster light at the Frontier - II. The Frontier Fields Clusters

    Science.gov (United States)

    Montes, Mireia; Trujillo, Ignacio

    2018-02-01

    Multiwavelength deep observations are a key tool to understand the origin of the diffuse light in clusters of galaxies: the intracluster light (ICL). For this reason, we take advantage of the Hubble Frontier Fields (HFF) survey to investigate the properties of the stellar populations of the ICL of its six massive intermediate redshift (0.3 1015 M⊙) clusters is formed by the stripping of MW-like objects that have been accreted at z < 1, in agreement with current simulations. We do not find any significant increase in the fraction of light of the ICL with cosmic time, although the redshift range explored is narrow to derive any strong conclusion. When exploring the slope of the stellar mass density profile, we found that the ICL of the HFF clusters follows the shape of their underlying dark matter haloes, in agreement with the idea that the ICL is the result of the stripping of galaxies at recent times.

  3. Coherent Eigenmodes in Homogeneous MHD Turbulence

    Science.gov (United States)

    Shebalin, John V.

    2010-01-01

    The statistical mechanics of Fourier models of ideal, homogeneous, incompressible magnetohydrodynamic (MHD) turbulence is discussed, along with their relevance for dissipative magnetofluids. Although statistical theory predicts that Fourier coefficients of fluid velocity and magnetic field are zero-mean random variables, numerical simulations clearly show that certain coefficients have a non-zero mean value that can be very large compared to the associated standard deviation, i.e., we have coherent structure. We use eigenanalysis of the modal covariance matrices in the probability density function to explain this phenomena in terms of `broken ergodicity', which is defined to occur when dynamical behavior does not match ensemble predictions on very long time-scales. We provide examples from 2-D and 3-D magnetohydrodynamic simulations of homogeneous turbulence, and show new results from long-time simulations of MHD turbulence with and without a mean magnetic field

  4. Computational Investigation of Extended-MHD Effects on Tokamak Plasmas

    Science.gov (United States)

    King, Jacob R.; Kruger, Scott E.

    2013-10-01

    We present studies with the extended-MHD NIMROD code of the tearing instability and edge-localized modes (ELMs). In our first study we use analytics and computations to examine tearing in a large-guide field with a nonzero pressure gradient where previous results show drift effects are stabilizing [Coppi, PoF (1964)]. Our work finds three new results: (1) At moderately large ion gyroradius the mode rotates at the electron drift velocity and there is no stabilization. (2) With collision-less drift reconnection, computations must also include electron gyroviscosity and advection. And (3) we derive a dispersion relation that exhibits diamagnetic stabilization and describes the transition between the electron-fluid-mediated regime of (1) and the semi-collisional regime [Drake and Lee, PoF (1977)]. Our second study investigates the transition from an ideal- to an extended-MHD model in an ELM unstable tokamak configuration. With the inclusion of a full generalized Ohm's law the growth rate is enhanced at intermediate wave-numbers and cut-off at large wave-numbers by diamagnetic effects consistent with analytics [Hastie et al., PoP (2003)]. Adding ion gyroviscosity to the model is stabilizing at large wave-numbers consistent with recent results [Xu et al., PoP (2013)]. Support provided by US DOE.

  5. Design Study: Rocket Based MHD Generator

    Science.gov (United States)

    1997-01-01

    This report addresses the technical feasibility and design of a rocket based MHD generator using a sub-scale LOx/RP rocket motor. The design study was constrained by assuming the generator must function within the performance and structural limits of an existing magnet and by assuming realistic limits on (1) the axial electric field, (2) the Hall parameter, (3) current density, and (4) heat flux (given the criteria of heat sink operation). The major results of the work are summarized as follows: (1) A Faraday type of generator with rectangular cross section is designed to operate with a combustor pressure of 300 psi. Based on a magnetic field strength of 1.5 Tesla, the electrical power output from this generator is estimated to be 54.2 KW with potassium seed (weight fraction 3.74%) and 92 KW with cesium seed (weight fraction 9.66%). The former corresponds to a enthalpy extraction ratio of 2.36% while that for the latter is 4.16%; (2) A conceptual design of the Faraday MHD channel is proposed, based on a maximum operating time of 10 to 15 seconds. This concept utilizes a phenolic back wall for inserting the electrodes and inter-electrode insulators. Copper electrode and aluminum oxide insulator are suggested for this channel; and (3) A testing configuration for the sub-scale rocket based MHD system is proposed. An estimate of performance of an ideal rocket based MHD accelerator is performed. With a current density constraint of 5 Amps/cm(exp 2) and a conductivity of 30 Siemens/m, the push power density can be 250, 431, and 750 MW/m(sup 3) when the induced voltage uB have values of 5, 10, and 15 KV/m, respectively.

  6. Magnetic Reconnection in a Compressible MHD Plasma

    Science.gov (United States)

    Hesse, Michael; Birn, Joachim; Zenitani, Seiji

    2011-01-01

    Using steady-state resistive MHD, magnetic reconnection is reinvestigated for conditions of high resistivity/low magnetic Reynolds number, when the thickness of the diffusion region is no longer small compared to its length. Implicit expressions for the reconnection rate and other reconnection parameters are derived based on the requirements of mass, momentum, and energy conservation. These expressions are solved via simple iterative procedures. Implications specifically for low Reynolds number/high resistivity are being discussed

  7. MHD simulations on an unstructured mesh

    Energy Technology Data Exchange (ETDEWEB)

    Strauss, H.R. [New York Univ., NY (United States); Park, W.; Belova, E.; Fu, G.Y. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Longcope, D.W. [Univ. of Montana, Missoula, MT (United States); Sugiyama, L.E. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1998-12-31

    Two reasons for using an unstructured computational mesh are adaptivity, and alignment with arbitrarily shaped boundaries. Two codes which use finite element discretization on an unstructured mesh are described. FEM3D solves 2D and 3D RMHD using an adaptive grid. MH3D++, which incorporates methods of FEM3D into the MH3D generalized MHD code, can be used with shaped boundaries, which might be 3D.

  8. Inductive ionospheric solver for magnetospheric MHD simulations

    Directory of Open Access Journals (Sweden)

    H. Vanhamäki

    2011-01-01

    Full Text Available We present a new scheme for solving the ionospheric boundary conditions required in magnetospheric MHD simulations. In contrast to the electrostatic ionospheric solvers currently in use, the new solver takes ionospheric induction into account by solving Faraday's law simultaneously with Ohm's law and current continuity. From the viewpoint of an MHD simulation, the new inductive solver is similar to the electrostatic solvers, as the same input data is used (field-aligned current [FAC] and ionospheric conductances and similar output is produced (ionospheric electric field. The inductive solver is tested using realistic, databased models of an omega-band and westward traveling surge. Although the tests were performed with local models and MHD simulations require a global ionospheric solution, we may nevertheless conclude that the new solution scheme is feasible also in practice. In the test cases the difference between static and electrodynamic solutions is up to ~10 V km−1 in certain locations, or up to 20-40% of the total electric field. This is in agreement with previous estimates. It should also be noted that if FAC is replaced by the ground magnetic field (or ionospheric equivalent current in the input data set, exactly the same formalism can be used to construct an inductive version of the KRM method originally developed by Kamide et al. (1981.

  9. MHD thrust vectoring of a rocket engine

    Science.gov (United States)

    Labaune, Julien; Packan, Denis; Tholin, Fabien; Chemartin, Laurent; Stillace, Thierry; Masson, Frederic

    2016-09-01

    In this work, the possibility to use MagnetoHydroDynamics (MHD) to vectorize the thrust of a solid propellant rocket engine exhaust is investigated. Using a magnetic field for vectoring offers a mass gain and a reusability advantage compared to standard gimbaled, elastomer-joint systems. Analytical and numerical models were used to evaluate the flow deviation with a 1 Tesla magnetic field inside the nozzle. The fluid flow in the resistive MHD approximation is calculated using the KRONOS code from ONERA, coupling the hypersonic CFD platform CEDRE and the electrical code SATURNE from EDF. A critical parameter of these simulations is the electrical conductivity, which was evaluated using a set of equilibrium calculations with 25 species. Two models were used: local thermodynamic equilibrium and frozen flow. In both cases, chlorine captures a large fraction of free electrons, limiting the electrical conductivity to a value inadequate for thrust vectoring applications. However, when using chlorine-free propergols with 1% in mass of alkali, an MHD thrust vectoring of several degrees was obtained.

  10. Exploring New Physics Frontiers Through Numerical Relativity.

    Science.gov (United States)

    Cardoso, Vitor; Gualtieri, Leonardo; Herdeiro, Carlos; Sperhake, Ulrich

    2015-01-01

    The demand to obtain answers to highly complex problems within strong-field gravity has been met with significant progress in the numerical solution of Einstein's equations - along with some spectacular results - in various setups. We review techniques for solving Einstein's equations in generic spacetimes, focusing on fully nonlinear evolutions but also on how to benchmark those results with perturbative approaches. The results address problems in high-energy physics, holography, mathematical physics, fundamental physics, astrophysics and cosmology.

  11. Exploring New Physics Frontiers Through Numerical Relativity

    Directory of Open Access Journals (Sweden)

    Vitor Cardoso

    2015-09-01

    Full Text Available The demand to obtain answers to highly complex problems within strong-field gravity has been met with significant progress in the numerical solution of Einstein’s equations – along with some spectacular results – in various setups. We review techniques for solving Einstein’s equations in generic spacetimes, focusing on fully nonlinear evolutions but also on how to benchmark those results with perturbative approaches. The results address problems in high-energy physics, holography, mathematical physics, fundamental physics, astrophysics and cosmology.

  12. New frontiers for tomorrow`s world

    Energy Technology Data Exchange (ETDEWEB)

    Kassler, P. [Shell International Petroleum Co. Ltd., London (United Kingdom)

    1994-12-31

    The conference paper deals with new frontiers and barricades in the global economic development and their influence on fuel consumption and energy source development. Topics discussed are incremental energy supply - new frontiers, world car population - new frontiers, OPEC crude production capacity vs call on OPEC, incremental world oil demand by region 1992-2000, oil resource cost curve, progress in seismic 1983-1991, Troll picture, cost reduction in renewables, sustained growth scenario, nuclear electricity capacity - France, OECD road transport fuels - barricades, and energy taxation. 18 figs.

  13. Optimization and industry new frontiers

    CERN Document Server

    Korotkikh, Victor

    2003-01-01

    Optimization from Human Genes to Cutting Edge Technologies The challenges faced by industry today are so complex that they can only be solved through the help and participation of optimization ex­ perts. For example, many industries in e-commerce, finance, medicine, and engineering, face several computational challenges due to the mas­ sive data sets that arise in their applications. Some of the challenges include, extended memory algorithms and data structures, new program­ ming environments, software systems, cryptographic protocols, storage devices, data compression, mathematical and statistical methods for knowledge mining, and information visualization. With advances in computer and information systems technologies, and many interdisci­ plinary efforts, many of the "data avalanche challenges" are beginning to be addressed. Optimization is the most crucial component in these efforts. Nowadays, the main task of optimization is to investigate the cutting edge frontiers of these technologies and systems ...

  14. New Frontiers of Land Control

    DEFF Research Database (Denmark)

    Lee Peluso, Nancy; Lund, Christian

    2011-01-01

    rights, and territories created, extracted, produced, or protected on land. Primitive and on-going forms of accumulation, frontiers, enclosures, territories, grabs, and racializations have all been associated with mechanisms for land control. Agrarian environments have been transformed by processes of de......Land questions have invigorated agrarian studies and economic history, with particular emphases on its control, since Marx. Words such as ‘exclusion’, ‘alienation’, ‘expropriation’, ‘dispossession’, and ‘violence’ describe processes that animate land histories and those of resources, property......-agrarianization, protected area establishment, urbanization, migration, land reform, resettlement, and re-peasantization. Even the classic agrarian question of how agriculture is influenced by capitalism has been reformulated multiple times at transformative conjunctures in the historical trajectories of these processes...

  15. NASA Lewis H2-O2 MHD program

    Science.gov (United States)

    Smith, M.; Nichols, L. D.; Seikel, G. R.

    1974-01-01

    Performance and power costs of H2-O2 combustion powered steam-MHD central power systems are estimated. Hydrogen gas is assumed to be transmitted by pipe from a remote coal gasifier into the city and converted to electricity in a steam MHD plant having an integral gaseous oxygen plant. These steam MHD systems appear to offer an attractive alternative to both in-city clean fueled conventional steam power plants and to remote coal fired power plants with underground electric transmission into the city. Status and plans are outlined for an experimental evaluation of H2-O2 combustion-driven MHD power generators at NASA Lewis Research Center.

  16. Frontiere pericolose: l’adattamento Dangerous frontiers: adaptation

    Directory of Open Access Journals (Sweden)

    Sandro Volpe

    2011-04-01

    riscrittura di un testo, una sua continuazione, una sua variazione. Se la traduzione cerca riparo nei confortevoli territori della somiglianza, l’adattamento – un buon adattamento – deve spingersi oltre, osare sul terreno della diversità. Partire da un testo significa ripartire, viaggiare, attraversare una frontiera per approdare altrove. E qualche volta, come auspicava Truffaut, fare «un’altra cosa, migliore».Discourses on adaptation revolve incessantly around a succession of deep-rooted clichés: at opposite ends the imaginary illusions of disappointed readers and the programmatic indifference of hardened film lovers. Theory should tenaciously oppose itself to common sense, but it's been bogged down in jargon and self-references: experts read each other's works, they position and reposition themselves, modify and revise their taxonomical grids, almost always triadic, engaged in endlessly redefining the continuum that goes from fidelity to originality. They simply ask that each adaptation fit into related compartments. With the only purpose of finding their bearings. But their terminology almost always reflects the same concern: an obsession with translatability. Doggedly formalizing a concept based on a wrong premise: because an adaptation is not a translation, it's an interpretation. Or, better, it isn't only an interpretation but certainly implies one. Of all the misunderstandings this is the most dangerous one because it doesn't have the alibi of ingenuousness. The whole exhausting debate on fidelity, even in its most recent declensions, falls through when the erroneousness of the premise is uncovered. If it's legitimate to judge a translation based on the principle of fidelity, this becomes entirely devoid of relevance when one considers an adaptation as something new, a re-writing of a text, its continuation, its variation. While a translation seeks refuge in the comfortable territories of similarity, an adaptation – a

  17. Biomembrane Frontiers Nanostructures, Models, and the Design of Life

    CERN Document Server

    Faller, Roland; Risbud, Subhash H; Jue, Thomas

    2009-01-01

    HANDBOOK OF MODERN BIOPHYSICS Series Editor Thomas Jue, PhD Handbook of Modern Biophysics brings current biophysics topics into focus, so that biology, medical, engineering, mathematics, and physical-science students or researchers can learn fundamental concepts and the application of new techniques in addressing biomedical challenges. Chapters explicate the conceptual framework of the physics formalism and illustrate the biomedical applications. With the addition of problem sets, guides to further study, and references, the interested reader can continue to explore independently the ideas presented. Volume II: Biomembrane Frontiers: Nanostructures, Models, and the Design of Life Editors: Roland Faller, PhD, Thomas Jue, PhD, Marjorie L. Longo, PhD, and Subhash H. Risbud, PhD In Biomembrane Frontiers: Nanostructures, Models, and the Design of Life, prominent researchers have established a foundation for the study of biophysics related to the following topics: Perspectives: Complexes in Liquids, 1900–2008 Mol...

  18. MHD heat and seed recovery technology project. Tenth quarterly report, April-June 1980

    Energy Technology Data Exchange (ETDEWEB)

    Petrick, M.; Johnson, T. R.

    1980-12-01

    The MHD Heat and Seed Recovery Technology Project at Argonne National Laboratory is obtaining information for the design and operation of the steam plant downstream of the MHD channel-diffuser, and of the seed regeneration process. The project goal is to supply the engineering data required in the design of components for prototype and demonstration MHD facilities. The primary effort of the HSR Technology Project at Argonne is directed toward experimental investigations of critical problem areas, such as (1) corrosion and erosion of refractories and metal alloys; (2) NO/sub x/ behavior in the radiant boiler and secondary combustor; (3) radiant boiler design to meet the multiple requirements of steam generation, NO/sub x/ decomposition, and seed-slag separation; (4) effects of solid or liquid seed deposits on heat transfer and gas flow in the steam and air heaters; (5) formation, growth, and deposition of seed-slag particles; and (6) character of the combustion gas effluents. These investigations are performed primarily in a 2-MW test facility, the Argonne MHD Process Engineering Laboratory (AMPEL). Other project activities are related to studies of the thermochemistry of the seed-slag combustion gas system, and evaluation of seed regeneration processes. Progress is reported.

  19. Nucleon measurements at the precision frontier

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Carl E. [Physics Department, College of William and Mary, Williamsburg, VA 23187 (United States)

    2013-11-07

    We comment on nucleon measurements at the precision frontier. As examples of what can be learned, we concentrate on three topics, which are parity violating scattering experiments, the proton radius puzzle, and the symbiosis between nuclear and atomic physics.

  20. Applied thermodynamics: A new frontier for biotechnology

    DEFF Research Database (Denmark)

    Mollerup, Jørgen

    2006-01-01

    The scientific career of one of the most outstanding scientists in molecular thermodynamics, Professor John M. Prausnitz at Berkeley, reflects the change in the agenda of molecular thermodynamics, from hydrocarbon chemistry to biotechnology. To make thermodynamics a frontier for biotechnology...

  1. Page 1 Materials for MHD channels 75 Figure 4. First Indian MHD ...

    Indian Academy of Sciences (India)

    under the influence of the electrical field also causes oxidation of the anodes. To minimise the possible deleterious reactions and degradation of the electrode system,. Mason et al (1975) have identified FeAl2O4—Fe3O4 spinel (figure 7) as a potential electrode for open cycle coal fired MHD cycles. This spinel-alumina ...

  2. The Substorm Cycle as Reproduced by Global MHD Models

    Science.gov (United States)

    Gordeev, E.; Sergee, V.; Tsyganenko, N.; Kuznetsova, M.; Rastaetter, Lutz; Raeder, J.; Toth, G.; Lyon, J.; Merkin, V.; Wiltberger, M.

    2017-01-01

    Recently, Gordeev et al. (2015) suggested a method to test global MHD models against statistical empirical data. They showed that four community-available global MHD models supported by the Community Coordinated Modeling Center (CCMC) produce a reasonable agreement with reality for those key parameters (the magnetospheric size, magnetic field, and pressure) that are directly related to the large-scale equilibria in the outer magnetosphere. Based on the same set of simulation runs, here we investigate how the models reproduce the global loading-unloading cycle. We found that in terms of global magnetic flux transport, three examined CCMC models display systematically different response to idealized2 h north then 2 h south interplanetary magnetic field (IMF) Bz variation. The LFM model shows a depressed return convection and high loading rate during the growth phase as well as enhanced return convection and high unloading rate during the expansion phase, with the amount of loaded unloaded magnetotail flux and the growth phase duration being the closest to their observed empirical values during isolated substorms. Two other models exhibit drastically different behavior. In the BATS-R-US model the plasma sheet convection shows a smooth transition to the steady convection regime after the IMF southward turning. In the Open GGCM a weak plasma sheet convection has comparable intensities during both the growth phase and the following slow unloading phase. We also demonstrate potential technical problem in the publicly available simulations which is related to post processing interpolation and could affect the accuracy of magnetic field tracing and of other related procedures.

  3. Superconducting magnet system for an experimental disk MHD facility

    NARCIS (Netherlands)

    Knoopers, H.G.; ten Kate, Herman H.J.; van de Klundert, L.J.M.; van de Klundert, L.J.M.

    1991-01-01

    A predesign of a split-pair magnet for a magnetohydrodynamic (MHD) facility for testing a 10-MW open-cycle disk or a 5-MW closed-cycle disk generator is presented. The magnet system consists of a NbTi and a Nb 3Sn section, which provide a magnetic field of 9 T in the active area of the MHD channel.

  4. Parameter regimes for slow, intermediate and fast MHD shocks

    NARCIS (Netherlands)

    Delmont, P.; Keppens, R.

    2011-01-01

    We investigate under which parameter regimes the magnetohydrodynamic (MHD) Rankine-Hugoniot conditions, which describe discontinuous solutions to the MHD equations, allow for slow, intermediate and fast shocks. We derive limiting values for the upstream and downstream shock parameters for which

  5. Combined effects of radiation and chemical reaction on MHD flow ...

    African Journals Online (AJOL)

    Influence of radiation and chemical reaction on MHD flow past a moving plate with Hall current is studied here. Earlier, we (2016) have studied unsteady MHD flow in porous media over exponentially accelerated plate with variable wall temperature and mass transfer along with Hall current. To study further, we are changing ...

  6. Annular MHD Physics for Turbojet Energy Bypass

    Science.gov (United States)

    Schneider, Steven J.

    2011-01-01

    The use of annular Hall type MHD generator/accelerator ducts for turbojet energy bypass is evaluated assuming weakly ionized flows obtained from pulsed nanosecond discharges. The equations for a 1-D, axisymmetric MHD generator/accelerator are derived and numerically integrated to determine the generator/accelerator performance characteristics. The concept offers a shockless means of interacting with high speed inlet flows and potentially offers variable inlet geometry performance without the complexity of moving parts simply by varying the generator loading parameter. The cycle analysis conducted iteratively with a spike inlet and turbojet flying at M = 7 at 30 km altitude is estimated to have a positive thrust per unit mass flow of 185 N-s/kg. The turbojet allowable combustor temperature is set at an aggressive 2200 deg K. The annular MHD Hall generator/accelerator is L = 3 m in length with a B(sub r) = 5 Tesla magnetic field and a conductivity of sigma = 5 mho/m for the generator and sigma= 1.0 mho/m for the accelerator. The calculated isentropic efficiency for the generator is eta(sub sg) = 84 percent at an enthalpy extraction ratio, eta(sub Ng) = 0.63. The calculated isentropic efficiency for the accelerator is eta(sub sa) = 81 percent at an enthalpy addition ratio, eta(sub Na) = 0.62. An assessment of the ionization fraction necessary to achieve a conductivity of sigma = 1.0 mho/m is n(sub e)/n = 1.90 X 10(exp -6), and for sigma = 5.0 mho/m is n(sub e)/n = 9.52 X 10(exp -6).

  7. Sustainable value assessment of farms using frontier efficiency benchmarks.

    Science.gov (United States)

    Van Passel, Steven; Van Huylenbroeck, Guido; Lauwers, Ludwig; Mathijs, Erik

    2009-07-01

    Appropriate assessment of firm sustainability facilitates actor-driven processes towards sustainable development. The methodology in this paper builds further on two proven methodologies for the assessment of sustainability performance: it combines the sustainable value approach with frontier efficiency benchmarks. The sustainable value methodology tries to relate firm performance to the use of different resources. This approach assesses contributions to corporate sustainability by comparing firm resource productivity with the resource productivity of a benchmark, and this for all resources considered. The efficiency is calculated by estimating the production frontier indicating the maximum feasible production possibilities. In this research, the sustainable value approach is combined with efficiency analysis methods to benchmark sustainability assessment. In this way, the production theoretical underpinnings of efficiency analysis enrich the sustainable value approach. The methodology is presented using two different functional forms: the Cobb-Douglas and the translog functional forms. The simplicity of the Cobb-Douglas functional form as benchmark is very attractive but it lacks flexibility. The translog functional form is more flexible but has the disadvantage that it requires a lot of data to avoid estimation problems. Using frontier methods for deriving firm specific benchmarks has the advantage that the particular situation of each company is taken into account when assessing sustainability. Finally, we showed that the methodology can be used as an integrative sustainability assessment tool for policy measures.

  8. Migrant decision-making in a frontier landscape

    Science.gov (United States)

    Salerno, Jonathan

    2016-04-01

    Across the tropics, rural farmers and livestock keepers use mobility as an adaptive livelihood strategy. Continued migration to and within frontier areas is widely viewed as a driver of environmental decline and biodiversity loss. Recent scholarship advances our understanding of migration decision-making in the context of changing climate and environments, and in doing so it highlights the variation in migration responses to primarily economic and environmental factors. Building on these insights, this letter investigates past and future migration decisions in a frontier landscape of Tanzania, East Africa. Combining field observations and household data within a multilevel modeling framework, the letter analyzes the explicit importance of social factors relative to economic and environmental factors in driving decisions to migrate or remain. Results indeed suggest that local community ties and non-local social networks drive both immobility and anticipated migration, respectively. In addition, positive interactions with local protected natural resource areas promote longer-term residence. Findings shed new light on how frontier areas transition to human dominated landscapes. This highlights critical links between migration behavior and the conservation of biodiversity and management of natural resources, as well as how migrants evolve to become integrated into communities.

  9. MHD Equations with Regularity in One Direction

    Directory of Open Access Journals (Sweden)

    Zujin Zhang

    2014-01-01

    Full Text Available We consider the 3D MHD equations and prove that if one directional derivative of the fluid velocity, say, ∂3u∈Lp0, T;LqR3, with 2/p + 3/q = γ ∈ [1,3/2, 3/γ ≤ q ≤ 1/(γ - 1, then the solution is in fact smooth.  This improves previous results greatly.

  10. Magnetic stresses in ideal MHD plasmas

    DEFF Research Database (Denmark)

    Jensen, V.O.

    1995-01-01

    The concept of magnetic stresses in ideal MHD plasma theory is reviewed and revisited with the aim of demonstrating its advantages as a basis for calculating and understanding plasma equilibria. Expressions are derived for the various stresses that transmit forces in a magnetized plasma...... and it is shown that the resulting magnetic forces on a finite volume element can be obtained by integrating the magnetic stresses over the surface of the element. The concept is used to rederive and discuss the equilibrium conditions for axisymmetric toroidal plasmas, including the virial theorem...

  11. Ionization fronts in coupled MHD-gas simulations

    Science.gov (United States)

    Wilson, A. D.; Diver, D. A.

    2017-09-01

    Partially ionized plasmas are ubiquitous in both nature and the laboratory, and their behaviour is best described by models which take into account the interactions between the neutral and charged species. We present a new non-linear, 3-dimensional, finite difference Gas-MHD Interactions Code designed to solve simultaneously the time evolution of fluid equations of both species in the conservation form as well as collisional interactions between them via appropriate choices of source term; in particular, we present results from this code in simulating Alfvén ionization in a partially ionized plasma. In this fashion, larger changes in the ionization fraction than were addressable in the linear limit are possible. Alfvén ionization is shown to impart plasmas with an inherent resistance to rapid recombination, where the recombination itself is significant enough to drive relative motion between the ionised and neutral species at speeds in excess of the critical velocity.

  12. Obesity: the new metabolic frontier

    Directory of Open Access Journals (Sweden)

    D.K. Yokaichiya

    2004-05-01

    Full Text Available Working on active learning strategies for web based courses, the Biochemical Education Research groupfrom USP and Unicamp;s departments of Biochemistry has developed the educational software Obesity:the new metabolic frontier. The software was designed to be used as a major reference to study thissubject on 2003 Biochemistry of Nutrition course, and was based on the most recent publications aboutobesity, specially concerning the leptin role in this metabolic disturb. The most relevant characteristicof this software is the use of animated models to represent the cellular response and the presentationof many other mechanisms involved in obesity. We also intended to focus the relationship betweenleptin and other mechanisms that lead to obesity. The teaching strategy consisted in providing thestudents with the software and a text about Obesity. After few days, they should discuss the topic ina two-hour synchronous discussions chat-rooms (specially designed for this purpose, with a TeachingAssistant;s (TA help. After the discussion, the students were asked to answer an evaluation surveyabout the activity and the software ecience to the learning process. The TAs were asked to evaluatethe software as a tool to help in teaching process. In the following week the students had to go backto the chat-rooms for an online synchronous test. The results of this experience (students and TAssatisfaction were very clear and stimulated us to go on with software development and to improvethe use of this kind of educational tool in Biochemistry classes.

  13. Characteristics of Linear MHD Generators with One or a Few Loads

    Energy Technology Data Exchange (ETDEWEB)

    Witalis, E.A.

    1966-02-15

    The theoretical performance of linear series segmented MHD generators with finite size electrodes and one or a few identical external loads is investigated. The analysis is an extension of our conformal mapping investigation previously reported. The electrical characteristics are evaluated as functions of the segmentation degree, the Hall parameter and the relative position of short-circuited electrodes. Special consideration is given to the influence of staggering the electrodes, i. e. shifting the relative positions of short-circuited electrodes. General electrical terminal characteristics, i. e. the full current-voltage relation, can not be obtained by the exact analytical method, which is applicable only to so-called design load conditions or infinitely long MHD channels. However, it is shown how the general properties can be explained qualitatively and calculated approximately by describing off-design modes of operation in terms of a fictitious 'effective' number of external loads.

  14. Nonlinear MHD dynamo operating at equipartition

    DEFF Research Database (Denmark)

    Archontis, V.; Dorch, Bertil; Nordlund, Åke

    2007-01-01

    Context.We present results from non linear MHD dynamo experiments with a three-dimensional steady and smooth flow that drives fast dynamo action in the kinematic regime. In the saturation regime, the system yields strong magnetic fields, which undergo transitions between an energy-equipartition a......Context.We present results from non linear MHD dynamo experiments with a three-dimensional steady and smooth flow that drives fast dynamo action in the kinematic regime. In the saturation regime, the system yields strong magnetic fields, which undergo transitions between an energy......-equipartition and a turbulent state. The generation and evolution of such strong magnetic fields is relevant for the understanding of dynamo action that occurs in stars and other astrophysical objects. Aims.We study the mode of operation of this dynamo, in the linear and non-linear saturation regimes. We also consider......, and that it can saturate at a level significantly higher than intermittent turbulent dynamos, namely at energy equipartition, for high values of the magnetic and fluid Reynolds numbers. The equipartition solution however does not remain time-independent during the simulation but exhibits a much more intricate...

  15. MHD simulation of plasma compression experiments

    Science.gov (United States)

    Reynolds, Meritt; Barsky, Sandra; de Vietien, Peter

    2017-10-01

    General Fusion (GF) is working to build a magnetized target fusion (MTF) power plant based on compression of magnetically-confined plasma by liquid metal. GF is testing this compression concept by collapsing solid aluminum liners onto plasmas formed by coaxial helicity injection in a series of experiments called PCS (Plasma Compression, Small). We simulate the PCS experiments using the finite-volume MHD code VAC. The single-fluid plasma model includes temperature-dependent resistivity and anisotropic heat transport. The time-dependent curvilinear mesh for MHD simulation is derived from LS-DYNA simulations of actual field tests of liner implosion. We will discuss how 3D simulations reproduced instability observed in the PCS13 experiment and correctly predicted stabilization of PCS14 by ramping the shaft current during compression. We will also present a comparison of simulated Mirnov and x-ray diagnostics with experimental measurements indicating that PCS14 compressed well to a linear compression ratio of 2.5:1.

  16. MHD limit cycles on FTU

    Science.gov (United States)

    Pucella, G.; Giovannozzi, E.; Buratti, P.; Cianfarani, C.

    2017-11-01

    The development of low-order tearing modes during density ramp-up in the high density regime on the Frascati Tokamak Upgrade is characterized by an initial ordinary stage, with a ‘one-to-one’ relation between mode amplitude and frequency, followed by the formation, on the amplitude/frequency plane, of ‘limit cycles’ with increasing area up to disruption for density limit if the density continues to grow. A critical mode amplitude for transition from smooth to cyclic behavior has been observed in experiments performed changing the line-averaged density, and the existence of such a threshold has been confirmed in experiments of real time control of tearing mode in the high density regime by means of electron cyclotron resonance heating. The amplitude and frequency modulations of the observed m/n=2/1 tearing mode (m and n are the poloidal and toroidal mode number, respectively) occur in few milliseconds, which is not in agreement with the diffusion resistive time of about two hundred milliseconds expected on the q=2 resonance from the non-linear theory. The origin of such modulations has been investigated, taking into account that in the high amplitude stages of the mode temporal evolution it is difficult to discriminate between non-linear effects and mode coupling mechanisms. Our analysis suggests that the formation of limit cycles could be due to a recursive island fragmentation, with a sort of self-healing phenomenon; in fact the island distortion increases before amplitude drops. Concerning the interaction with modes of different helicity, our experiments seem to indicate that the presence of the q=3 resonance in the plasma is necessary for the occurrence of deep and regular limit cycles for the 2/1 tearing mode.

  17. All About Audio Equalization: Solutions and Frontiers

    Directory of Open Access Journals (Sweden)

    Vesa Välimäki

    2016-05-01

    Full Text Available Audio equalization is a vast and active research area. The extent of research means that one often cannot identify the preferred technique for a particular problem. This review paper bridges those gaps, systemically providing a deep understanding of the problems and approaches in audio equalization, their relative merits and applications. Digital signal processing techniques for modifying the spectral balance in audio signals and applications of these techniques are reviewed, ranging from classic equalizers to emerging designs based on new advances in signal processing and machine learning. Emphasis is placed on putting the range of approaches within a common mathematical and conceptual framework. The application areas discussed herein are diverse, and include well-defined, solvable problems of filter design subject to constraints, as well as newly emerging challenges that touch on problems in semantics, perception and human computer interaction. Case studies are given in order to illustrate key concepts and how they are applied in practice. We also recommend preferred signal processing approaches for important audio equalization problems. Finally, we discuss current challenges and the uncharted frontiers in this field. The source code for methods discussed in this paper is made available at https://code.soundsoftware.ac.uk/projects/allaboutaudioeq.

  18. The "Frontier" And Frontier Guards in Banat - a Socio- Historical Approach

    Directory of Open Access Journals (Sweden)

    SEBASTIAN ŞTEFĂNUCĂ

    2010-06-01

    Full Text Available The researchers preoccupied with the regional identity potential of Ţara Almăjului and the Eastern area of the Banat mountain region, Romania, cannot avoid the particular historical evolution, in the last three centuries, of these regions. This is true precisely when the starting point is represented by the Wealth Community (Comunitatea de Avere - a form of collective ownership of a large part of the forests in the abovementioned regions and of certain buildings - a direct remnant of the Austrian frontier past, which was abolished during the Communist period. At that time (the second half of the 18th century, this form of collective ownership generated deep and irreversible social, administrative, architectural, legal and economic transformations which are visible to this day. Apart from an elite preoccupied with historical studies, in relation to which we notice the open affirmation of identity valences which we look for, and apart from another elite which is interested in reinstating and managing the Wealth Community, the locals seem detached both from the past and the frontier, as well as from the attempts to reinstate the Wealth Community. The only truly relevant form of ownership is individual ownership. We consider that this attitude is a variant of what Lucian Blaga called a "boycott of history". Therefore, the identity looked for seems to be constituted not so much by opposing, than by ignoring the past and the disinterest towards collective ownership, to which we can add the suspicion with respect to the intentions of people holding positions within the local administration and state authorities generally.

  19. Laboratory Plasma Source as an MHD Model for Astrophysical Jets

    Science.gov (United States)

    Mayo, Robert M.

    1997-01-01

    The significance of the work described herein lies in the demonstration of Magnetized Coaxial Plasma Gun (MCG) devices like CPS-1 to produce energetic laboratory magneto-flows with embedded magnetic fields that can be used as a simulation tool to study flow interaction dynamic of jet flows, to demonstrate the magnetic acceleration and collimation of flows with primarily toroidal fields, and study cross field transport in turbulent accreting flows. Since plasma produced in MCG devices have magnetic topology and MHD flow regime similarity to stellar and extragalactic jets, we expect that careful investigation of these flows in the laboratory will reveal fundamental physical mechanisms influencing astrophysical flows. Discussion in the next section (sec.2) focuses on recent results describing collimation, leading flow surface interaction layers, and turbulent accretion. The primary objectives for a new three year effort would involve the development and deployment of novel electrostatic, magnetic, and visible plasma diagnostic techniques to measure plasma and flow parameters of the CPS-1 device in the flow chamber downstream of the plasma source to study, (1) mass ejection, morphology, and collimation and stability of energetic outflows, (2) the effects of external magnetization on collimation and stability, (3) the interaction of such flows with background neutral gas, the generation of visible emission in such interaction, and effect of neutral clouds on jet flow dynamics, and (4) the cross magnetic field transport of turbulent accreting flows. The applicability of existing laboratory plasma facilities to the study of stellar and extragalactic plasma should be exploited to elucidate underlying physical mechanisms that cannot be ascertained though astrophysical observation, and provide baseline to a wide variety of proposed models, MHD and otherwise. The work proposed herin represents a continued effort on a novel approach in relating laboratory experiments to

  20. Frontiers for Laboratory Research of Magnetic Reconnection

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Hantao [Princeton University; Guo, Fan [Los Alamos National Laboratory

    2015-07-16

    Magnetic reconnection occcurs throughout heliophysical and astrophysical plasmas as well as in laboratory fusion plasmas. Two broad categories of reconnection models exist: collisional MHD and collisionless kinetic. Eight major questions with respect to magnetic connection are set down, and past and future devices for studying them in the laboratory are described. Results of some computerized simulations are compared with experiments.

  1. Energetic electrons, hard x-ray emission and MHD activity studies in the IR-T1 tokamak.

    Science.gov (United States)

    Agah, K Mikaili; Ghoranneviss, M; Elahi, A Salar

    2015-01-01

    Determinations of plasma parameters as well as the Magnetohydrodynamics (MHD) activity, energetic electrons energy and energy confinement time are essential for future fusion reactors experiments and optimized operation. Also some of the plasma information can be deduced from these parameters, such as plasma equilibrium, stability, and MHD instabilities. In this contribution we investigated the relation between energetic electrons, hard x-ray emission and MHD activity in the IR-T1 Tokamak. For this purpose we used the magnetic diagnostics and a hard x-ray spectroscopy in IR-T1 tokamak. A hard x-ray emission is produced by collision of the runaway electrons with the plasma particles or limiters. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons.

  2. Pesticide use and biodiversity conservation in the Amazonian agricultural frontier

    NARCIS (Netherlands)

    Schiesari, L.; Waichman, A.; Brock, T.C.M.; Adams, C.; Grillitsch, B.

    2013-01-01

    Agricultural frontiers are dynamic environments characterized by the conversion of native habitats to agriculture. Because they are currently concentrated in diverse tropical habitats, agricultural frontiers are areas where the largest number of species is exposed to hazardous land management

  3. MHD Simulations of the Plasma Flow in the Magnetic Nozzle

    Science.gov (United States)

    Smith, T. E. R.; Keidar, M.; Sankaran, K.; olzin, K. A.

    2013-01-01

    magnetic field in both the near- and far-field regions. However, in that work the downstream domain was constrained to a channel of constant cross-sectional area. In the present work we seek to address this issue by modeling the downstream region with a domain that permits free expansion of the plasma, permitting a better evaluation of the downstream effects the applied field has on the plasma. The inlet boundary conditions and applied magnetic field values will also be varied to determine the effect the initial plasma energy content and applied magnetic field energy density have on the near- and far-field plasma properties on the MHD code. This will determine the effect of inlet boundary conditions on the results downstream and address issues related to the restrictive numerical domain previously used.

  4. strategic military colonisation: the cape eastern frontier 1806 – 1872

    African Journals Online (AJOL)

    Linda

    after the Sixth Frontier War (1834–1835) and bears the Royal Engineers' stamp. The plan clearly illustrates the growth of an urban settlement around what was originally a military fort. The first era of frontier forts. From the earliest British administration, fortifications were planned. Colonel. Graham instituted a series of frontier ...

  5. Frontier Homes. Save Our History[TM]. Teacher's Guide.

    Science.gov (United States)

    A&E Network, New York, NY.

    This lesson plan, based on the Arts and Entertainment documentary "Frontier Homes," consists of four segments which examine a style of historic dwelling built by settlers on the frontier: the post and beam structures built by English settlers in New England; the log houses constructed by pioneers on the forested frontier; sod houses…

  6. Activation of MHD reconnection on ideal timescales

    CERN Document Server

    Landi, S; Del Zanna, L; Tenerani, A; Pucci, F

    2016-01-01

    Magnetic reconnection in laboratory, space and astrophysical plasmas is often invoked to explain explosive energy release and particle acceleration. However, the timescales involved in classical models within the macroscopic MHD regime are far too slow to match the observations. Here we revisit the tearing instability by performing visco-resistive two-dimensional numerical simulations of the evolution of thin current sheets, for a variety of initial configurations and of values of the Lunquist number $S$, up to $10^7$. Results confirm that when the critical aspect ratio of $S^{1/3}$ is reached in the reconnecting current sheets, the instability proceeds on ideal (Alfv\\'enic) macroscopic timescales, as required to explain observations. Moreover, the same scaling is seen to apply also to the local, secondary reconnection events triggered during the nonlinear phase of the tearing instability, thus accelerating the cascading process to increasingly smaller spatial and temporal scales. The process appears to be ro...

  7. Application of electron closures in extended MHD

    Science.gov (United States)

    Held, Eric; Adair, Brett; Taylor, Trevor

    2017-10-01

    Rigorous closure of the extended MHD equations in plasma fluid codes includes the effects of electron heat conduction along perturbed magnetic fields and contributions of the electron collisional friction and stress to the extended Ohms law. In this work we discuss application of a continuum numerical solution to the Chapman-Enskog-like electron drift kinetic equation using the NIMROD code. The implementation is a tightly-coupled fluid/kinetic system that carefully addresses time-centering in the advance of the fluid variables with their kinetically-computed closures. Comparisons of spatial accuracy, computational efficiency and required velocity space resolution are presented for applications involving growing magnetic islands in cylindrical and toroidal geometry. The reduction in parallel heat conduction due to particle trapping in toroidal geometry is emphasized. Work supported by DOE under Grant Nos. DE-FC02-08ER54973 and DE-FG02-04ER54746.

  8. MHD stable regime of the tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, C.Z.; Furth, H.P.; Boozer, A.H.

    1986-10-01

    A broad family of tokamak current profiles is found to be stable against ideal and resistive MHD kink modes for 1 less than or equal to q(0), with q(a) as low 2. For 0.5 less than or equal to q(0) < and q(a) > 1, current profiles can be found that are unstable only to the m = 1, n = 1 mode. A specific ''optimal'' tokamak profile can be selected from the range of stable solutions, by imposing a common upper limit on dj/dr - corresponding in ohmic equilibrium to a limitation of dT/sub e//dr by anomalous transport.

  9. MHD simulation of the Bastille day event

    Energy Technology Data Exchange (ETDEWEB)

    Linker, Jon, E-mail: linkerj@predsci.com; Torok, Tibor; Downs, Cooper; Lionello, Roberto; Titov, Viacheslav; Caplan, Ronald M.; Mikić, Zoran; Riley, Pete [Predictive Science Inc., 9990 Mesa Rim Road, Suite 170, San Diego CA, USA 92121 (United States)

    2016-03-25

    We describe a time-dependent, thermodynamic, three-dimensional MHD simulation of the July 14, 2000 coronal mass ejection (CME) and flare. The simulation starts with a background corona developed using an MDI-derived magnetic map for the boundary condition. Flux ropes using the modified Titov-Demoulin (TDm) model are used to energize the pre-event active region, which is then destabilized by photospheric flows that cancel flux near the polarity inversion line. More than 10{sup 33} ergs are impulsively released in the simulated eruption, driving a CME at 1500 km/s, close to the observed speed of 1700km/s. The post-flare emission in the simulation is morphologically similar to the observed post-flare loops. The resulting flux rope that propagates to 1 AU is similar in character to the flux rope observed at 1 AU, but the simulated ICME center passes 15° north of Earth.

  10. MHD Instabilities in Simple Plasma Configuration

    Science.gov (United States)

    1984-01-01

    without subscripts. As already men- tioned there is no equilibrium flow of the plasma. We now scalar mul- tiply Eq. (III-1) by V to obtain av poV’ V...tearing modes. VIILA - MHD Modes With Two Dimensional Structure Recall from the last three chapters, that in slab geometry, the appropriate modes always had...P>V) =- (V• V- V<V>) (X-5a) <P>A-V+ a< +ji<V>-V<V>+pV-V<V> +<p><V> .VV+Vt 1 (Vxil) x <B> +(V x <B>) x > 41r = -v + <A- > Ot - Av .V<V> + <AsV> .V<V

  11. World economics for mankind's frontier

    Science.gov (United States)

    Finch, Edward R.

    2007-04-01

    In Acta Astronautica, Vol. 56, No. 5, March 2006, at ISSN0094-5765 there appears the article entitled “Will space actually be the Final Frontier of humankind?” written by Giancarlo Genta, and Michael Rycroft. This Acta Astronautica article requires amplification on the economic side. The writer of this article was personally present at the Apollo 11th launchings for the first landing on the Moon, by Buzz Aldrin and others. The Apollo 11 take off to the Moon, from Cape Carnival, did not leave the situation “so humankind seems forever to be bound to its own planet!” There was nothing pessimistic about the launch of Apollo 11. It is written that there was a lack of vision at that time, which is also not correct. The ‘Final Frontier’ myth was never mentioned on that occasion. At Apollo 11 we did take planet earth's “first faltering step for mankind” on the path towards a space faring civilization, exactly as these two authors later correctly mention. Now with the US Presidential initiatives “Moon, Mars and Beyond,” the authors suggested that it “will depend on social, political and economic issues rather than technological and scientific ones.” This Academy Note respectfully submits that all of these factors social, political and economic issues, plus psychological and scientific ones, instead of, “rather than technical and scientific ones” are going to be the determining factors of the speed of progress of the exploration of the entire universe, and particularly the sun in our Milky Way Galaxy. Russia and Ukraine are now on same, deep-space policy directions. The attention of the readers of this Academy Note is called to the current “Cosmic Collision” excellent presentation at the Hayden Planetarium, located at the Museum of National History in the City of New York. It shows the past, the present and the future of international humankind in exploring space and the creation of the universe, with particular reference to the protons of our

  12. MHD stability limits in the TCV Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Reimerdes, H. [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)

    2001-07-01

    Magnetohydrodynamic (MHD) instabilities can limit the performance and degrade the confinement of tokamak plasmas. The Tokamak a Configuration Variable (TCV), unique for its capability to produce a variety of poloidal plasma shapes, has been used to analyse various instabilities and compare their behaviour with theoretical predictions. These instabilities are perturbations of the magnetic field, which usually extend to the plasma edge where they can be detected with magnetic pick-up coils as magnetic fluctuations. A spatially dense set of magnetic probes, installed inside the TCV vacuum vessel, allows for a fast observation of these fluctuations. The structure and temporal evolution of coherent modes is extracted using several numerical methods. In addition to the setup of the magnetic diagnostic and the implementation of analysis methods, the subject matter of this thesis focuses on four instabilities, which impose local and global stability limits. All of these instabilities are relevant for the operation of a fusion reactor and a profound understanding of their behaviour is required in order to optimise the performance of such a reactor. Sawteeth, which are central relaxation oscillations common to most standard tokamak scenarios, have a significant effect on central plasma parameters. In TCV, systematic scans of the plasma shape have revealed a strong dependence of their behaviour on elongation {kappa} and triangularity {delta}, with high {kappa}, and low {delta} leading to shorter sawteeth with smaller crashes. This shape dependence is increased by applying central electron cyclotron heating. The response to additional heating power is determined by the role of ideal or resistive MHD in triggering the sawtooth crash. For plasma shapes where additional heating and consequently, a faster increase of the central pressure shortens the sawteeth, the low experimental limit of the pressure gradient within the q = 1 surface is consistent with ideal MHD predictions. The

  13. 3D adaptive grid MHD simulations of the global heliosphere with self- consistent fluid neutral hydrogen

    Science.gov (United States)

    Opher, M.; Liewer, P.; Gombosi, T.; Manchester, W.; Dezeeuw, D.; Powell, K.; Sokolov, I.; Toth, G.

    A three dimensional adaptive grid magnetohydrodynamic (MHD) model of the interaction of the solar wind with the local interstellar medium is presented. The code used is the BATS-R-US time-dependent adaptive grid three-dimensional magnetohydrodynamic, which is similar to the code used by Linde et al. JGR, 103, 1889 (1998). The magnetic field of both the solar wind and the interstellar medium are included. The latitute dependence of the solar wind is also taken into account. The neutral atoms are included self-consistently as a fluid, without assuming constant the density, velocity or temperature as previous 3D MHD studies. The location of the termination shock and heliopause in the steady state solution for different values and directions of interstellar magnetic field are presented and compared with previous results. We also present results where we isolated the effects of neutrals and magnetic field showing their relative importance, in particular the heliopause.

  14. R-Process Nucleosynthesis in MHD Jet Explosions of Core-Collapse Supernovae

    Directory of Open Access Journals (Sweden)

    Motoaki Saruwatari

    2013-01-01

    Full Text Available We investigate the r-process nucleosynthesis during the magnetohydrodynamical (MHD explosion of a supernova in a helium star of 3.3 M⊙, where effects of neutrinos are taken into account using the leakage scheme in the two-dimensional (2D hydrodynamic code. Jet-like explosion due to the combined effects of differential rotation and magnetic field is able to erode the lower electron fraction matter from the inner layers. We find that the ejected material of low electron fraction responsible for the r-process comes out from just outside the neutrino sphere deep inside the Fe-core. It is found that heavy element nucleosynthesis depends on the initial conditions of rotational and magnetic fields. In particular, the third peak of the distribution is significantly overproduced relative to the solar system abundances, which would indicate a possible r-process site owing to MHD jets in supernovae.

  15. Snowmass Computing Frontier: Computing for the Cosmic Frontier, Astrophysics, and Cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, A. [Univ. of Washington, Seattle, WA (United States); Habib, S. [Argonne National Lab. (ANL), Lemont, IL (United States); Szalay, A. [Johns Hopkins Univ., Baltimore, MD (United States); Borrill, J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Fuller, G. [Univ. of California, San Diego, CA (United States); Gnedin, N. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Heitmann, K. [Argonne National Lab. (ANL), Lemont, IL (United States); Jacobs, D. [Arizona State Univ., Tempe, AZ (United States); Lamb, D. [Univ. of Chicago, IL (United States); Mezzacappa, T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Messer, B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Myers, S. [National Radio Astronomy Observatory, Socorro, NM (United States); Nord, B. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Nugent, P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); O' Shea, B. [Michigan State Univ., East Lansing, MI (United States); Ricker, P. [Univ. of Illinois, Urbana-Champaign, IL (United States); Schneider, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2013-11-12

    This document presents (off-line) computing requrements and challenges for Cosmic Frontier science, covering the areas of data management, analysis, and simulations. We invite contributions to extend the range of covered topics and to enhance the current descriptions.

  16. Local conservative regularizations of compressible MHD and neutral flows

    CERN Document Server

    Krishnaswami, Govind S; Thyagaraja, Anantanarayanan

    2016-01-01

    Ideal systems like MHD and Euler flow may develop singularities in vorticity (w = curl v). Viscosity and resistivity provide dissipative regularizations of the singularities. In this paper we propose a minimal, local, conservative, nonlinear, dispersive regularization of compressible flow and ideal MHD, in analogy with the KdV regularization of the 1D kinematic wave equation. This work extends and significantly generalizes earlier work on incompressible Euler and ideal MHD. It involves a micro-scale cutoff length lambda which is a function of density, unlike in the incompressible case. In MHD, it can be taken to be of order the electron collisionless skin depth c/omega_pe. Our regularization preserves the symmetries of the original systems, and with appropriate boundary conditions, leads to associated conservation laws. Energy and enstrophy are subject to a priori bounds determined by initial data in contrast to the unregularized systems. A Hamiltonian and Poisson bracket formulation is developed and applied ...

  17. An Implicit, Conservative Multi-Temperature MHD Algorithm

    National Research Council Canada - National Science Library

    Shumlak, Uri

    2001-01-01

    .... The algorithm was based on a Roe-type approximate Riemann solver. The algorithm was implemented in a code to model the time-dependent, three-dimensional, arbitrary-geometry MHD model which includes viscous and resistive effects...

  18. Universal equations of unsteady two-dimensional MHD boundary layer whose temperature varies with time

    Directory of Open Access Journals (Sweden)

    Boričić Zoran

    2009-01-01

    Full Text Available This paper concerns with unsteady two-dimensional temperature laminar magnetohydrodynamic (MHD boundary layer of incompressible fluid. It is assumed that induction of outer magnetic field is function of longitudinal coordinate with force lines perpendicular to the body surface on which boundary layer forms. Outer electric filed is neglected and magnetic Reynolds number is significantly lower then one i.e. considered problem is in inductionless approximation. Characteristic properties of fluid are constant because velocity of flow is much lower than speed of light and temperature difference is small enough (under 50ºC . Introduced assumptions simplify considered problem in sake of mathematical solving, but adopted physical model is interesting from practical point of view, because its relation with large number of technically significant MHD flows. Obtained partial differential equations can be solved with modern numerical methods for every particular problem. Conclusions based on these solutions are related only with specific temperature MHD boundary layer problem. In this paper, quite different approach is used. First new variables are introduced and then sets of similarity parameters which transform equations on the form which don't contain inside and in corresponding boundary conditions characteristics of particular problems and in that sense equations are considered as universal. Obtained universal equations in appropriate approximation can be solved numerically once for all. So-called universal solutions of equations can be used to carry out general conclusions about temperature MHD boundary layer and for calculation of arbitrary particular problems. To calculate any particular problem it is necessary also to solve corresponding momentum integral equation.

  19. Pioneers on the Astrosociological Frontier: Introduction to the First Symposium on Astrosociology

    Science.gov (United States)

    Pass, Jim

    2009-03-01

    Astrosociology is a relatively new multidisciplinary field that scientifically investigates astrosocial phenomena (i.e., social, cultural, and behavioral patterns related to space exploration and related issues). The "astrosociological frontier" represents an analogous framework to that of space as the "final frontier," as both territories are quite empty of human activity and ripe for exploration. This focus on the astrosociological frontier provides insights about the need for a social-scientific field to place the human dimension in its proper place alongside familiar space community concerns such as engineering. The astrosociological frontier refers to the lack of development of astrosociology as a scientific field—or anything like it earlier during the space age. It includes both the 1) unoccupied "landscape" in academia characterized by the lack of astrosociology in its curricula and 2) dearth of space research focused on social-scientific (i.e., astrosociological) topics both inside and outside of traditional academia in collaboration with traditional space community members and the new space entrepreneurs. Within academia, the "frontier" is characterized by a lack of courses, programs, and departments dedicated to astrosociology. In the future, proponents of this new field expect the astrosociological frontier to become characterized by a growing number of "settlements" in curricula across the country and world. As things stand, however, the early "astrosociological pioneers" include those who seek to explore these underappreciated issues within academic and professional climates that discourage them from pursuing their interests. Thus, the "1st Symposium on Astrosociology" at the 2009 SPESIF conference represents an important expedition consisting of pioneering participants willing to venture into a little-explored territory with the goal of developing astrosociology.

  20. A Conserved Cross Helicity for Non-Barotropic MHD

    CERN Document Server

    Yahalom, A

    2016-01-01

    Cross helicity is not conserved in non-barotropic magnetohydrodynamics (MHD) (as opposed to barotropic or incompressible MHD). Here we show that variational analysis suggests a new kind of cross helicity which is conserved in the non barotropic case. The non barotropic cross helicity reduces to the standard cross helicity under barotropic assumptions. The new cross helicity is conserved even for topologies for which the variational principle does not apply.

  1. Evaluation of the ECAS open cycle MHD power plant design

    Science.gov (United States)

    Seikel, G. R.; Staiger, P. J.; Pian, C. C. P.

    1978-01-01

    The Energy Conversion Alternatives Study (ECAS) MHD/steam power plant is described. The NASA critical evaluation of the design is summarized. Performance of the MHD plant is compared to that of the other type ECAS plant designs on the basis of efficiency and the 30-year levelized cost of electricity. Techniques to improve the plant design and the potential performance of lower technology plants requiring shorter development time and lower development cost are then discussed.

  2. Frontiers in Materials Science and Technology

    Indian Academy of Sciences (India)

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

    Frontiers in Materials Science and Technology. FOREWORD. Over the last few decades of the twentieth century, great inroads were made in further development of established materials by improved and novel processing routes. It was also a period of discovery of a range of new materials such as high temperature ...

  3. The Research Frontier in Corporate Governance

    DEFF Research Database (Denmark)

    Ahrens, Thomas; Filatotchev, Igor; Thomsen, Steen

    2011-01-01

    In this paper we attempt to identify the research frontier in corporate governance using three different approaches: (1) what challenges does the financial crisis 2007–2009 pose for corporate governance research? We show that the financial crisis is a huge natural experiment which has exposed gaps...

  4. Frontiers in nuclear medicine and technology. Editorial

    NARCIS (Netherlands)

    Lemahieu, I; Viergever, M.A.; van Rijk, P.P.; Dierckx, R.A.

    This special issue of Computerized Medical Imaging and Graphics contains the full length papers of invited oral communications presented at the symposium entitled: “Frontiers in Nuclear Medicine Technology” held at the Studie Centrum voor Kernenergie — Centre d'Etude de l'Energie Nucléaire (SCK —

  5. Adult Literacy Education on the Canadian Frontier.

    Science.gov (United States)

    Walter, Pierre

    2003-01-01

    Canada's Frontier College began in 1899 to bring literacy and citizenship education to immigrant men; in the 1920s it offered university education. However, its early history embodied a legacy of nativism, anticommunism, racism, and sexism as it attempted to assimilate adult literacy learners into Anglo-Canadian sociocultural norms. (Contains 19…

  6. Sport without Frontiers: Just an Unrealistic Wish?

    Science.gov (United States)

    Koch, Mathias

    1990-01-01

    Describes and recommends the project, Sports without Frontiers, as a useful tool in the integration of foreign immigrants. Suggests that employment of foreigners in West Germany's job market means the needs of foreigners must be addressed. Argues this program promotes social integration through sports. (NL)

  7. Conditions for a Possible Dialogue between Theology and Science from the Perspective of the Concept of Frontier

    Directory of Open Access Journals (Sweden)

    Saplacan Calin

    2014-11-01

    Full Text Available Is there a way without conquests and wars to be found in the relationship of theology and science? This relation is analyzed from the perspective of the concept of frontier in order to establish the conditions for a possible dialogue. Paradoxically, the frontier unites and divides at the same time. On the one hand, the frontier marks the differences, on the other hand it appears as a crossing, a passageway. The frontier is an in-between, a huge space in which the two sides are called together to explain each other, and in order to create a passage between the two sides. The methodological framework of analysis is the approach of analytical theology to distinctions in language and significance. As a frame of reference, the possibility conditions for a philosophical dialogue between phenomenology and analytical philosophy have been considered.

  8. Intracluster light at the Frontier: A2744

    Energy Technology Data Exchange (ETDEWEB)

    Montes, Mireia; Trujillo, Ignacio, E-mail: mireia.montes.quiles@gmail.com [Instituto de Astrofísica de Canarias,c/Vía Láctea s/n, E-38205 La Laguna, Tenerife (Spain)

    2014-10-20

    The ultra-deep multiwavelength Hubble Space Telescope Frontier Fields coverage of the Abell Cluster 2744 is used to derive the stellar population properties of its intracluster light (ICL). The restframe colors of the ICL of this intermediate redshift (z = 0.3064) massive cluster are bluer (g – r = 0.68 ± 0.04; i – J = 0.56 ± 0.01) than those found in the stellar populations of its main galaxy members (g – r = 0.83 ± 0.01; i – J = 0.75 ± 0.01). Based on these colors, we derive the following mean metallicity Z = 0.018 ± 0.007 for the ICL. The ICL age is 6 ± 3 Gyr younger than the average age of the most massive galaxies of the cluster. The fraction of stellar mass in the ICL component comprises at least 6% of the total stellar mass of the galaxy cluster. Our data are consistent with a scenario where the bulk of the ICL of A2744 has been formed relatively recently (z < 1). The stellar population properties of the ICL suggest that this diffuse component is mainly the result of the disruption of infalling galaxies with similar characteristics in mass (M {sub *} ∼ 3 × 10{sup 10} M {sub ☉}) and metallicity than our own Milky Way. The amount of ICL mass in the central part of the cluster (<400 kpc) is equivalent to the disruption of 4-6 Milky-Way-type galaxies.

  9. Broken Ergodicity in MHD Turbulence in a Spherical Domain

    Science.gov (United States)

    Shebalin, John V.; wang, Yifan

    2011-01-01

    Broken ergodicity (BE) occurs in Fourier method numerical simulations of ideal, homogeneous, incompressible magnetohydrodynamic (MHD) turbulence. Although naive statistical theory predicts that Fourier coefficients of fluid velocity and magnetic field are zero-mean random variables, numerical simulations clearly show that low-wave-number coefficients have non-zero mean values that can be very large compared to the associated standard deviation. In other words, large-scale coherent structure (i.e., broken ergodicity) in homogeneous MHD turbulence can spontaneously grow out of random initial conditions. Eigenanalysis of the modal covariance matrices in the probability density functions of ideal statistical theory leads to a theoretical explanation of observed BE in homogeneous MHD turbulence. Since dissipation is minimal at the largest scales, BE is also relevant for resistive magnetofluids, as evidenced in numerical simulations. Here, we move beyond model magnetofluids confined by periodic boxes to examine BE in rotating magnetofluids in spherical domains using spherical harmonic expansions along with suitable boundary conditions. We present theoretical results for 3-D and 2-D spherical models and also present computational results from dynamical simulations of 2-D MHD turbulence on a rotating spherical surface. MHD turbulence on a 2-D sphere is affected by Coriolus forces, while MHD turbulence on a 2-D plane is not, so that 2-D spherical models are a useful (and simpler) intermediate stage on the path to understanding the much more complex 3-D spherical case.

  10. On the Measurements of Numerical Viscosity and Resistivity in Eulerian MHD Codes

    Energy Technology Data Exchange (ETDEWEB)

    Rembiasz, Tomasz; Obergaulinger, Martin; Cerdá-Durán, Pablo; Aloy, Miguel-Ángel [Departamento de Astronomía y Astrofísica, Universidad de Valencia, C/Dr. Moliner 50, E-46100 Burjassot (Spain); Müller, Ewald, E-mail: tomasz.rembiasz@uv.es [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany)

    2017-06-01

    We propose a simple ansatz for estimating the value of the numerical resistivity and the numerical viscosity of any Eulerian MHD code. We test this ansatz with the help of simulations of the propagation of (magneto)sonic waves, Alfvén waves, and the tearing mode (TM) instability using the MHD code Aenus. By comparing the simulation results with analytical solutions of the resistive-viscous MHD equations and an empirical ansatz for the growth rate of TMs, we measure the numerical viscosity and resistivity of Aenus. The comparison shows that the fast magnetosonic speed and wavelength are the characteristic velocity and length, respectively, of the aforementioned (relatively simple) systems. We also determine the dependence of the numerical viscosity and resistivity on the time integration method, the spatial reconstruction scheme and (to a lesser extent) the Riemann solver employed in the simulations. From the measured results, we infer the numerical resolution (as a function of the spatial reconstruction method) required to properly resolve the growth and saturation level of the magnetic field amplified by the magnetorotational instability in the post-collapsed core of massive stars. Our results show that it is most advantageous to resort to ultra-high-order methods (e.g., the ninth-order monotonicity-preserving method) to tackle this problem properly, in particular, in three-dimensional simulations.

  11. High magnetic field MHD generator program. Final report, July 1, 1976-December 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Eustis, R. H.; Kruger, C. H.; Mitchner, M.; Self, S. A.; Koester, J. K.; Nakamura, T.

    1980-04-01

    A theoretical and experimental program was undertaken to investigate MHD channel phenomena which are important at high magnetic fields. The areas studied were inhomogeneity effects, boundary layers, Hall field breakdown and electrode configuration and current concentrations. In addition, a program was undertaken to study steady-state combustion disk and linear channels in an existing 6 Tesla magnet of small dimensions. The structure of the inhomogeneities in the Stanford M-2 was characterized and compared with theoretical results from a linearized perturbation analysis. General agreement was obtained and the analysis was used to compute stability regions for large size generators. The Faraday electrical connection was found to be more stable than the Hall or diagonal wall connections. Boundary layer profile measurements were compared with theoretical calculations with good agreement. Extrapolation of the calculations to pilot scale MHD channels indicates that Hartmann effects are important in the analysis of the sidewall, and Joule heating is important in calculating heat transfer and voltage drops for the electrode wall. Hall field breakdown was shown to occur both in the plasma and through the interelectrode insulator with the insulator breakdown threshold voltage lower than the plasma value. The threshold voltage was shown to depend on the interelectrode gap but was relatively independent of plasma conditions. Experiments were performed at 5.5 Tesla with both disk and linear MHD channels.

  12. Present understanding of MHD and heat transfer phenomena for liquid metal blankets

    Energy Technology Data Exchange (ETDEWEB)

    Kirillov, I.R. [Institute of Electrophysical, St. Petersburg (Russian Federation); Barleon, L. [IATF, Karlsruhe (Germany); Reed, C.B. [Argonne National Lab., IL (United States)] [and others

    1994-12-31

    Liquid metals (Li, Li17Pb83, Pb) are considered as coolants in many designs of fusion reactor blankets. To estimate their potential and to make an optimal design, one has to know the magnetohydrodynamic (MHD) and heat transfer characteristics of liquid metal flow in the magnetic field. Such flows with high characteristic parameter values (Hartmann number M and interaction parameter N) open up a relatively new field in Magnetohydrodynamics requiring both theoretical and experimental efforts. A review of experimental work done for the last ten years in different countries shows that there are some data on MHD/HT characteristics in straight channels of simple geometry under fusion reactor relevant conditions (M>>1, N>>1) and not enough data for complex flow geometries. Future efforts should be directed to investigation of MHD/HT in straight channels with perfect and imperfect electroinsulated walls, including those with controlled imperfections, and in channels of complex geometry. The experiments are not simple, since the fusion relevant conditions require facilities with magnetic fields at, or even higher than, 5-7 T in comparatively large volumes. International cooperation in constructing and operating these facilities may be of great help.

  13. EVIDENCE OF ACTIVE MHD INSTABILITY IN EULAG-MHD SIMULATIONS OF SOLAR CONVECTION

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, Nicolas; Strugarek, Antoine; Charbonneau, Paul, E-mail: nicolas.laws@gmail.ca, E-mail: strugarek@astro.umontreal.ca, E-mail: paulchar@astro.umontreal.ca [Département de Physique, Université de Montréal, C.P. 6128 Succ. Centre-ville, Montréal, Qc H3C 3J7 (Canada)

    2015-11-10

    We investigate the possible development of magnetohydrodynamical instabilities in the EULAG-MHD “millennium simulation” of Passos and Charbonneau. This simulation sustains a large-scale magnetic cycle characterized by solar-like polarity reversals taking place on a regular multidecadal cadence, and in which zonally oriented bands of strong magnetic fields accumulate below the convective layers, in response to turbulent pumping from above in successive magnetic half-cycles. Key aspects of this simulation include low numerical dissipation and a strongly sub-adiabatic fluid layer underlying the convectively unstable layers corresponding to the modeled solar convection zone. These properties are conducive to the growth and development of two-dimensional instabilities that are otherwise suppressed by stronger dissipation. We find evidence for the action of a non-axisymmetric magnetoshear instability operating in the upper portions of the stably stratified fluid layers. We also investigate the possibility that the Tayler instability may be contributing to the destabilization of the large-scale axisymmetric magnetic component at high latitudes. On the basis of our analyses, we propose a global dynamo scenario whereby the magnetic cycle is driven primarily by turbulent dynamo action in the convecting layers, but MHD instabilities accelerate the dissipation of the magnetic field pumped down into the overshoot and stable layers, thus perhaps significantly influencing the magnetic cycle period. Support for this scenario is found in the distinct global dynamo behaviors observed in an otherwise identical EULAG-MHD simulations, using a different degree of sub-adiabaticity in the stable fluid layers underlying the convection zone.

  14. Feasibility and limitations of oxcarbazepine monitoring using salivary monohydroxycarbamazepine (MHD).

    Science.gov (United States)

    Miles, Michael V; Tang, Peter H; Ryan, Melody A; Grim, Shellee A; Fakhoury, Toufic A; Strawsburg, Richard H; DeGrauw, Ton J; Baumann, Robert J

    2004-06-01

    The purpose of this study is to determine the feasibility of using 10-hydroxy-10,11-dihydrocarbazepine (MHD) concentration in saliva as an alternative to serum for the therapeutic monitoring of oxcarbazepine (OXC) treatment. Investigators identified subjects seen in neurology clinics at the University of Kentucky Chandler Medical Center. Patients were eligible if they agreed to participate in this study, were taking oxcarbazepine, and if a serum MHD concentration had been ordered by their physician. Unstimulated saliva specimens (0.25 mL minimum) were collected in the clinic and frozen until analysis. Blood samples were obtained by phlebotomy. Serum specimens were analyzed by a reference laboratory. Saliva MHD concentrations were determined by high-performance liquid chromatography in the Clinical Laboratory at the Cincinnati Children's Hospital Medical Center. Linear regression analysis was used to evaluate correlations. Saliva and blood specimens were collected from 28 epilepsy patients, but usable samples were obtained from only 23. The mean serum MHD concentration was 23.9 +/- 10.0 microg/mL, and the mean saliva concentration was 23.1 +/- 10.1 microg/mL. There was a significant positive correlation between the serum and saliva concentrations: saliva (y) = 0.95 serum (x) + 0.39; r = 0.941; n = 23; P MHD concentration ratio was 0.96 +/- 0.15. The results of the current study indicate that the relationship between freely flowing (unstimulated) saliva and serum concentrations of MHD is sufficient for therapeutic drug monitoring. A limitation of saliva MHD monitoring is that individuals who have difficulty producing small quantities of saliva or who have viscous saliva should generally be avoided for this type of monitoring. It is also recommended to avoid saliva collection within 8 hours after OXC dosing to allow complete absorption and transformation of the parent drug.

  15. MHD Gauge Fields: Helicities and Casimirs

    Science.gov (United States)

    Hu, Q.; Webb, G. M.; Zank, G. P.; Anco, S.

    2016-12-01

    Clebsch potential gauge field theory for magnetohydrodynamics is developed based in part on the theory of Calkin (1963). It is shown how the polarization vector P in Calkin's approach, naturally arises from the Lagrange multiplier constraint equation for Faraday's equation for the magnetic induction B, or alternatively from the magnetic vector potential form of Faraday's equation. Gauss's equation, (divergence of Bis zero), is incorporated in the variational principle by means of a Lagrange multiplier constraint. Noether's theorem, and gauge symmetries are used to derive the conservation laws for (a) magnetic helicity (b) cross helicity, (c) fluid helicity for non-magnetized fluids, and (d) a class of conservation laws associated with curl and divergence equations, which applies to Faraday's equation and Gauss's equation. The magnetic helicity conservation law is due to a gauge symmetry in MHD and not due to a fluid relabelling symmetry. The analysis is carried out for a non-barotropic gas. The cross helicity and fluid helicity conservation are nonlocal conservation laws, that reduce to local conservation laws for the case of a barotropic gas. The connections between gauge symmetries, Clebsch potentials and Casimirs are developed. It is shown that the gauge symmetry functionals in the work of Henyey (1982) satisfy the Casimir equations.

  16. Current systems of coronal loops in 3D MHD simulations

    Science.gov (United States)

    Warnecke, J.; Chen, F.; Bingert, S.; Peter, H.

    2017-11-01

    Aims: We study the magnetic field and current structure associated with a coronal loop. Through this we investigate to what extent the assumptions of a force-free magnetic field break down and where they might be justified. Methods: We analyze a three-dimensional (3D) magnetohydrodynamic (MHD) model of the solar corona in an emerging active region with the focus on the structure of the forming coronal loops. The lower boundary of this simulation is taken from a model of an emerging active region. As a consequence of the emerging magnetic flux and the horizontal motions at the surface a coronal loop forms self-consistently. We investigate the current density along magnetic field lines inside (and outside) this loop and study the magnetic and plasma properties in and around this loop. The loop is defined as the bundle of field lines that coincides with enhanced emission in extreme UV. Results: We find that the total current along the emerging loop changes its sign from being antiparallel to parallel to the magnetic field. This is caused by the inclination of the loop together with the footpoint motion. Around the loop, the currents form a complex non-force-free helical structure. This is directly related to a bipolar current structure at the loop footpoints at the base of the corona and a local reduction of the background magnetic field (I.e., outside the loop) caused by the plasma flow into and along the loop. Furthermore, the locally reduced magnetic pressure in the loop allows the loop to sustain a higher density, which is crucial for the emission in extreme UV. The action of the flow on the magnetic field hosting the loop turns out to also be responsible for the observed squashing of the loop. Conclusions: The complex magnetic field and current system surrounding it can only be modeled in 3D MHD models where the magnetic field has to balance the plasma pressure. A one-dimensional coronal loop model or a force-free extrapolation cannot capture the current system

  17. High-order conservative finite difference GLM-MHD schemes for cell-centered MHD

    Science.gov (United States)

    Mignone, Andrea; Tzeferacos, Petros; Bodo, Gianluigi

    2010-08-01

    We present and compare third- as well as fifth-order accurate finite difference schemes for the numerical solution of the compressible ideal MHD equations in multiple spatial dimensions. The selected methods lean on four different reconstruction techniques based on recently improved versions of the weighted essentially non-oscillatory (WENO) schemes, monotonicity preserving (MP) schemes as well as slope-limited polynomial reconstruction. The proposed numerical methods are highly accurate in smooth regions of the flow, avoid loss of accuracy in proximity of smooth extrema and provide sharp non-oscillatory transitions at discontinuities. We suggest a numerical formulation based on a cell-centered approach where all of the primary flow variables are discretized at the zone center. The divergence-free condition is enforced by augmenting the MHD equations with a generalized Lagrange multiplier yielding a mixed hyperbolic/parabolic correction, as in Dedner et al. [J. Comput. Phys. 175 (2002) 645-673]. The resulting family of schemes is robust, cost-effective and straightforward to implement. Compared to previous existing approaches, it completely avoids the CPU intensive workload associated with an elliptic divergence cleaning step and the additional complexities required by staggered mesh algorithms. Extensive numerical testing demonstrate the robustness and reliability of the proposed framework for computations involving both smooth and discontinuous features.

  18. Feasibility of MHD submarine propulsion. Phase II, MHD propulsion: Testing in a two Tesla test facility

    Energy Technology Data Exchange (ETDEWEB)

    Doss, E.D. [ed.] [Argonne National Lab., IL (United States); Sikes, W.C. [ed.] [Newport News Shipbuilding and Dry Dock Co., VA (United States)

    1992-09-01

    This report describes the work performed during Phase 1 and Phase 2 of the collaborative research program established between Argonne National Laboratory (ANL) and Newport News Shipbuilding and Dry Dock Company (NNS). Phase I of the program focused on the development of computer models for Magnetohydrodynamic (MHD) propulsion. Phase 2 focused on the experimental validation of the thruster performance models and the identification, through testing, of any phenomena which may impact the attractiveness of this propulsion system for shipboard applications. The report discusses in detail the work performed in Phase 2 of the program. In Phase 2, a two Tesla test facility was designed, built, and operated. The facility test loop, its components, and their design are presented. The test matrix and its rationale are discussed. Representative experimental results of the test program are presented, and are compared to computer model predictions. In general, the results of the tests and their comparison with the predictions indicate that thephenomena affecting the performance of MHD seawater thrusters are well understood and can be accurately predicted with the developed thruster computer models.

  19. Analysis of resource efficiency: a production frontier approach.

    Science.gov (United States)

    Hoang, Viet-Ngu

    2014-05-01

    This article integrates the material/energy flow analysis into a production frontier framework to quantify resource efficiency (RE). The emergy content of natural resources instead of their mass content is used to construct aggregate inputs. Using the production frontier approach, aggregate inputs will be optimised relative to given output quantities to derive RE measures. This framework is superior to existing RE indicators currently used in the literature. Using the exergy/emergy content in constructing aggregate material or energy flows overcomes a criticism that mass content cannot be used to capture different quality of differing types of resources. Derived RE measures are both 'qualitative' and 'quantitative', whereas existing RE indicators are only qualitative. An empirical examination into the RE of 116 economies was undertaken to illustrate the practical applicability of the new framework. The results showed that economies, on average, could reduce the consumption of resources by more than 30% without any reduction in per capita gross domestic product (GDP). This calculation occurred after adjustments for differences in the purchasing power of national currencies. The existence of high variations in RE across economies was found to be positively correlated with participation of people in labour force, population density, urbanisation, and GDP growth over the past five years. The results also showed that economies of a higher income group achieved higher RE, and those economies that are more dependent on imports and primary industries would have lower RE performance. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Frontiers in alley cropping: Transformative solutions for temperate agriculture.

    Science.gov (United States)

    Wolz, Kevin J; Lovell, Sarah T; Branham, Bruce E; Eddy, William C; Keeley, Keefe; Revord, Ronald S; Wander, Michelle M; Yang, Wendy H; DeLucia, Evan H

    2017-12-08

    Annual row crops dominate agriculture around the world and have considerable negative environmental impacts, including significant greenhouse gas emissions. Transformative land-use solutions are necessary to mitigate climate change and restore critical ecosystem services. Alley cropping (AC)-the integration of trees with crops-is an agroforestry practice that has been studied as a transformative, multifunctional land-use solution. In the temperate zone, AC has strong potential for climate change mitigation through direct emissions reductions and increases in land-use efficiency via overyielding compared to trees and crops grown separately. In addition, AC provides climate change adaptation potential and ecological benefits by buffering alley crops to weather extremes, diversifying income to hedge financial risk, increasing biodiversity, reducing soil erosion, and improving nutrient- and water-use efficiency. The scope of temperate AC research and application has been largely limited to simple systems that combine one timber tree species with an annual grain. We propose two frontiers in temperate AC that expand this scope and could transform its climate-related benefits: (i) diversification via woody polyculture and (ii) expanded use of tree crops for food and fodder. While AC is ready now for implementation on marginal lands, we discuss key considerations that could enhance the scalability of the two proposed frontiers and catalyze widespread adoption. © 2017 John Wiley & Sons Ltd.

  1. Mapping Frontier Research in the Humanities

    DEFF Research Database (Denmark)

    -academic fields and supplemented by new transdisciplinary methods focusing on solving grand societal challenges, such as globalisation, multiculturalism, equality, democracy, security and health. Given the nature of these challenges and the ways in which university leadership has been organised, the very notion...... in more complex landscapes of collective identities, networks, and constraints that open for new forms of intellectual leadership in the 21st century. Link: http://www.bloomsbury.com/uk/mapping-frontier-research-in-the-humanities-9781472597687/...

  2. BARD: Interpreting new frontier energy collider physics

    Energy Technology Data Exchange (ETDEWEB)

    Knuteson, Bruce; /MIT; Mrenna, Stephen; /Fermilab

    2006-02-01

    No systematic procedure currently exists for inferring the underlying physics from discrepancies observed in high energy collider data. We present Bard, an algorithm designed to facilitate the process of model construction at the energy frontier. Top-down scans of model parameter space are discarded in favor of bottom-up diagrammatic explanations of particular discrepancies, an explanation space that can be exhaustively searched and conveniently tested with existing analysis tools.

  3. Mapping Frontier Research in the Humanities

    DEFF Research Database (Denmark)

    Knowledge production in academia today is burgeoning and increasingly interdisciplinary in nature. Research within the humanities is no exception: it is distributed across a variety of methodic styles of research and increasingly involves interactions with fields outside the narrow confines...... of the university. As a result, the notion of liberal arts and humanities within Western universities is undergoing profound transformations. In Mapping Frontier Research in the Humanities, the contributors explore this transformative process. What are the implications, both for the modes of research...

  4. Automated Identification of MHD Mode Bifurcation and Locking in Tokamaks

    Science.gov (United States)

    Riquezes, J. D.; Sabbagh, S. A.; Park, Y. S.; Bell, R. E.; Morton, L. A.

    2017-10-01

    Disruption avoidance is critical in reactor-scale tokamaks such as ITER to maintain steady plasma operation and avoid damage to device components. A key physical event chain that leads to disruptions is the appearance of rotating MHD modes, their slowing by resonant field drag mechanisms, and their locking. An algorithm has been developed that automatically detects bifurcation of the mode toroidal rotation frequency due to loss of torque balance under resonant braking, and mode locking for a set of shots using spectral decomposition. The present research examines data from NSTX, NSTX-U and KSTAR plasmas which differ significantly in aspect ratio (ranging from A = 1.3 - 3.5). The research aims to examine and compare the effectiveness of different algorithms for toroidal mode number discrimination, such as phase matching and singular value decomposition approaches, and to examine potential differences related to machine aspect ratio (e.g. mode eigenfunction shape variation). Simple theoretical models will be compared to the dynamics found. Main goals are to detect or potentially forecast the event chain early during a discharge. This would serve as a cue to engage active mode control or a controlled plasma shutdown. Supported by US DOE Contracts DE-SC0016614 and DE-AC02-09CH11466.

  5. Wall functions for numerical modeling of laminar MHD flows

    CERN Document Server

    Widlund, O

    2003-01-01

    general wall function treatment is presented for the numerical modeling of laminar magnetohydrodynamic (MHD) flows. The wall function expressions are derived analytically from the steady-state momentum and electric potential equations, making use only of local variables of the numerical solution. No assumptions are made regarding the orientation of the magnetic field relative to the wall, nor of the magnitude of the Hartmann number, or the wall conductivity. The wall functions are used for defining implicit boundary conditions for velocity and electric potential, and for computing mass flow and electrical currents in near wall-cells. The wall function treatment was validated in a finite volume formulation, and compared with an analytic solution for a fully developed channel flow in a transverse magnetic field. For the case with insulating walls, a uniform 20 x 20 grid, and Hartmann numbers Ha = [10,30,100], the accuracy of pressure drop and wall shear stress predictions was [1.1%,1.6%,0.5%], respectively. Com...

  6. Comparing MHD simulations of RFP plasmas to RELAX experiments

    Science.gov (United States)

    McCollam, K. J.; den Hartog, D. J.; Jacobson, C. M.; Sauppe, J. P.; Masamune, S.; Sanpei, A.

    2015-11-01

    Standard reversed-field pinch (RFP) plasmas provide a nonlinear dynamical system as a validation domain for numerical MHD simulation codes, which can be applied to general toroidal confinement scenarios including tokamaks. Using the NIMROD code, we calculate linear stability and simulate the nonlinear evolution of plasmas similar to those in the RELAX RFP experiment, whose relatively modest Lundquist numbers of order 104 make the simulations tractable given present computing resources. The chosen RELAX cases cover a broad range of RFP reversal parameters and have also been previously simulated with the MIPS code (N. Mizuguchi et al., TH/P3-26, IAEA FEC, 2012). Experimental diagnostics that can be used for validation purposes include Thomson scattering for electron temperature, interferometry for electron density, SXR imaging, and external and internal magnetic probes. RELAX's small aspect ratio (~ 2) motivates a comparison study using toroidal and cylindrical geometries in NIMROD. This work is supported by the U.S. DOE and NSF and by the Japan Society for the Promotion of Science.

  7. A MHD channel study for the ETF conceptual design

    Science.gov (United States)

    Wang, S. Y.; Staiger, P. J.; Smith, J. M.

    1981-01-01

    The procedures and computations used to identify an MHD channel for a 540 mW(I) EFT-scale plant are presented. Under the assumed constraints of maximum E(x), E(y), J(y) and Beta; results show the best plant performance is obtained for active length, L is approximately 12 M, whereas in the initial ETF studies, L is approximately 16 M. As MHD channel length is reduced from 16 M, the channel enthalpy extraction falls off, slowly. This tends to reduce the MHD power output; however, the shorter channels result in lower heat losses to the MHD channel cooling water which allows for the incorporation of more low pressure boiler feedwater heaters into the system and an increase in steam plant efficiency. The net result of these changes is a net increase in the over all MHD/steam plant efficiency. In addition to the sensitivity of various channel parameters, the trade-offs between the level of oxygen enrichment and the electrical stress on the channel are also discussed.

  8. MHD Flow Control and Power Generation in Low-Temperature Supersonic Flows

    National Research Council Canada - National Science Library

    Gogineni, Sivaram P; Adamovich, Igor V

    2006-01-01

    .... MHD effect on the flow is detected from flow static-pressure measurements. The observed static-pressure change is due to the MHD interaction and not Joule heating of the flow in the crossed discharge...

  9. Interstellar MHD Turbulence and Star Formation

    Science.gov (United States)

    Vázquez-Semadeni, Enrique

    This chapter reviews the nature of turbulence in the Galactic interstellar medium (ISM) and its connections to the star formation (SF) process. The ISM is turbulent, magnetized, self-gravitating, and is subject to heating and cooling processes that control its thermodynamic behavior, causing it to behave approximately isobarically, in spite of spanning several orders of magnitude in density and temperature. The turbulence in the warm and hot ionized components of the ISM appears to be trans- or subsonic, and thus to behave nearly incompressibly. However, the neutral warm and cold components are highly compressible, as a consequence of both thermal instability (TI) in the atomic gas and of moderately-to-strongly supersonic motions in the roughly isothermal cold atomic and molecular components. Within this context, we discuss: (1) the production and statistical distribution of turbulent density fluctuations in both isothermal and polytropic media; (2) the nature of the clumps produced by TI, noting that, contrary to classical ideas, they in general accrete mass from their environment in spite of exhibiting sharp discontinuities at their boundaries; (3) the density-magnetic field correlation (and, at low densities, lack thereof) in turbulent density fluctuations, as a consequence of the superposition of the different wave modes in the turbulent flow; (4) the evolution of the mass-to-magnetic flux ratio (MFR) in density fluctuations as they are built up by dynamic compressions; (5) the formation of cold, dense clouds aided by TI, in both the hydrodynamic (HD) and the magnetohydrodynamic (MHD) cases; (6) the expectation that star-forming molecular clouds are likely to be undergoing global gravitational contraction, rather than being near equilibrium, as generally believed, and (7) the regulation of the star formation rate (SFR) in such gravitationally contracting clouds by stellar feedback which, rather than keeping the clouds from collapsing, evaporates and disperses

  10. Lattice Boltzmann Large Eddy Simulation Model of MHD

    CERN Document Server

    Flint, Christopher

    2016-01-01

    The work of Ansumali \\textit{et al.}\\cite{Ansumali} is extended to Two Dimensional Magnetohydrodynamic (MHD) turbulence in which energy is cascaded to small spatial scales and thus requires subgrid modeling. Applying large eddy simulation (LES) modeling of the macroscopic fluid equations results in the need to apply ad-hoc closure schemes. LES is applied to a suitable mesoscopic lattice Boltzmann representation from which one can recover the MHD equations in the long wavelength, long time scale Chapman-Enskog limit (i.e., the Knudsen limit). Thus on first performing filter width expansions on the lattice Boltzmann equations followed by the standard small Knudsen expansion on the filtered lattice Boltzmann system results in a closed set of MHD turbulence equations provided we enforce the physical constraint that the subgrid effects first enter the dynamics at the transport time scales. In particular, a multi-time relaxation collision operator is considered for the density distribution function and a single rel...

  11. MHD Flows in Compact Astrophysical Objects Accretion, Winds and Jets

    CERN Document Server

    Beskin, Vasily S

    2010-01-01

    Accretion flows, winds and jets of compact astrophysical objects and stars are generally described within the framework of hydrodynamical and magnetohydrodynamical (MHD) flows. Analytical analysis of the problem provides profound physical insights, which are essential for interpreting and understanding the results of numerical simulations. Providing such a physical understanding of MHD Flows in Compact Astrophysical Objects is the main goal of this book, which is an updated translation of a successful Russian graduate textbook. The book provides the first detailed introduction into the method of the Grad-Shafranov equation, describing analytically the very broad class of hydrodynamical and MHD flows. It starts with the classical examples of hydrodynamical accretion onto relativistic and nonrelativistic objects. The force-free limit of the Grad-Shafranov equation allows us to analyze in detail the physics of the magnetospheres of radio pulsars and black holes, including the Blandford-Znajek process of energy e...

  12. Oxygen-enriched air for MHD power plants

    Science.gov (United States)

    Ebeling, R. W., Jr.; Cutting, J. C.; Burkhart, J. A.

    1979-01-01

    Cryogenic air-separation process cycle variations and compression schemes are examined. They are designed to minimize net system power required to supply pressurized, oxygen-enriched air to the combustor of an MHD power plant with a coal input of 2000 MWt. Power requirements and capital costs for oxygen production and enriched air compression for enrichment levels from 13 to 50% are determined. The results are presented as curves from which total compression power requirements can be estimated for any desired enrichment level at any delivery pressure. It is found that oxygen enrichment and recuperative heating of MHD combustor air to 1400 F yields near-term power plant efficiencies in excess of 45%. A minimum power compression system requires 167 MW to supply 330 lb of oxygen per second and costs roughly 100 million dollars. Preliminary studies show MHD/steam power plants to be competitive with plants using high-temperature air preheaters burning gas.

  13. The temporal behaviour of MHD waves in a partially ionized prominence-like plasma: Effect of heating and cooling

    Science.gov (United States)

    Ballester, J. L.; Carbonell, M.; Soler, R.; Terradas, J.

    2018-01-01

    Context. During heating or cooling processes in prominences, the plasma microscopic parameters are modified due to the change of temperature and ionization degree. Furthermore, if waves are excited on this non-stationary plasma, the changing physical conditions of the plasma also affect wave dynamics. Aims: Our aim is to study how temporal variation of temperature and microscopic plasma parameters modify the behaviour of magnetohydrodynamic (MHD) waves excited in a prominence-like hydrogen plasma. Methods: Assuming optically thin radiation, a constant external heating, the full expression of specific internal energy, and a suitable energy equation, we have derived the profiles for the temporal variation of the background temperature. We have computed the variation of the ionization degree using a Saha equation, and have linearized the single-fluid MHD equations to study the temporal behaviour of MHD waves. Results: For all the MHD waves considered, the period and damping time become time dependent. In the case of Alfvén waves, the cut-off wavenumbers also become time dependent and the attenuation rate is completely different in a cooling or heating process. In the case of slow waves, while it is difficult to distinguish the slow wave properties in a cooling partially ionized plasma from those in an almost fully ionized plasma, the period and damping time of these waves in both plasmas are completely different when the plasma is heated. The temporal behaviour of the Alfvén and fast wave is very similar in the cooling case, but in the heating case, an important difference appears that is related with the time damping. Conclusions: Our results point out important differences in the behaviour of MHD waves when the plasma is heated or cooled, and show that a correct interpretation of the observed prominence oscillations is very important in order to put accurate constraints on the physical situation of the prominence plasma under study, that is, to perform prominence

  14. Ambipolar diffusion in low-mass star formation. I. General comparison with the ideal MHD case

    DEFF Research Database (Denmark)

    Masson, Jacques; Chabrier, Gilles; Hennebelle, Patrick

    2015-01-01

    braking processes, allowing the formation of disk structures. Magnetically supported outflows launched in ideal MHD models are weakened when using non-ideal MHD. Contrary to ideal MHD misalignment between the initial rotation axis and the magnetic field direction does not significantly affect the results...

  15. A kinetic-MHD model for low frequency phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, C.Z.

    1991-07-01

    A hybrid kinetic-MHD model for describing low-frequency phenomena in high beta anisotropic plasmas that consist of two components: a low energy core component and an energetic component with low density. The kinetic-MHD model treats the low energy core component by magnetohydrodynamic (MHD) description, the energetic component by kinetic approach such as the gyrokinetic equation, and the coupling between the dynamics of these two components through plasma pressure in the momentum equation. The kinetic-MHD model optimizes both the physics contents and the theoretical efforts in studying low frequency MHD waves and transport phenomena in general magnetic field geometries, and can be easily modified to include the core plasma kinetic effects if necessary. It is applicable to any magnetized collisionless plasma system where the parallel electric field effects are negligibly small. In the linearized limit two coupled eigenmode equations for describing the coupling between the transverse Alfven type and the compressional Alfven type waves are derived. The eigenmode equations are identical to those derived from the full gyrokinetic equation in the low frequency limit and were previously analyzed both analytically nd numerically to obtain the eigenmode structure of the drift mirror instability which explains successfully the multi-satellite observation of antisymmetric field-aligned structure of the compressional magnetic field of Pc 5 waves in the magnetospheric ring current plasma. Finally, a quadratic form is derived to demonstrate the stability of the low-frequency transverse and compressional Alfven type instabilities in terms of the pressure anisotropy parameter {tau} and the magnetic field curvature-pressure gradient parameter. A procedure for determining the stability of a marginally stable MHD wave due to wave-particle resonances is also presented.

  16. Nonlinear Terms of MHD Equations for Homogeneous Magnetized Shear Flow

    CERN Document Server

    Dimitrov, Z D; Hristov, T S; Mishonov, T M

    2011-01-01

    We have derived the full set of MHD equations for incompressible shear flow of a magnetized fluid and considered their solution in the wave-vector space. The linearized equations give the famous amplification of slow magnetosonic waves and describe the magnetorotational instability. The nonlinear terms in our analysis are responsible for the creation of turbulence and self-sustained spectral density of the MHD (Alfven and pseudo-Alfven) waves. Perspectives for numerical simulations of weak turbulence and calculation of the effective viscosity of accretion disks are shortly discussed in k-space.

  17. Frontiers in statistical quality control

    CERN Document Server

    Wilrich, Peter-Theodor

    2004-01-01

    This volume treats the four main categories of Statistical Quality Control: General SQC Methodology, On-line Control including Sampling Inspection and Statistical Process Control, Off-line Control with Data Analysis and Experimental Design, and, fields related to Reliability. Experts with international reputation present their newest contributions.

  18. MHD equilibrium of toroidal fusion plasma with stationary flows; Rownowaga MHD toroidalnej plazmy termojadrowej z przeplywami

    Energy Technology Data Exchange (ETDEWEB)

    Galkowski, A. [Institute of Atomic Energy, Otwock-Swierk (Poland)

    1994-12-31

    Non-linear ideal MHD equilibria in axisymmetric system with flows are examined, both in 1st and 2nd ellipticity regions. Evidence of the bifurcation of solutions is provided and numerical solutions of several problems in a tokamak geometry are given, exhibiting bifurcation phenomena. Relaxation of plasma in the presence of zero-order flows is studied in a realistic toroidal geometry. The field aligned flow allows equilibria with finite pressure gradient but with homogeneous temperature distribution. Numerical calculations have been performed for the 1st and 2nd ellipticity regimes of the extended Grad-Shafranov-Schlueter equation. Numerical technique, alternative to the well-known Grad`s ADM methods has been proposed to deal with slow adiabatic evolution of toroidal plasma with flows. The equilibrium problem with prescribed adiabatic constraints may be solved by simultaneous calculations of flux surface geometry and original profile functions. (author). 178 refs, 37 figs, 5 tabs.

  19. MHD instabilities in astrophysical plasmas: very different from MHD instabilities in tokamaks!

    Science.gov (United States)

    Goedbloed, J. P.

    2018-01-01

    The extensive studies of MHD instabilities in thermonuclear magnetic confinement experiments, in particular of the tokamak as the most promising candidate for a future energy producing machine, have led to an ‘intuitive’ description based on the energy principle that is very misleading for most astrophysical plasmas. The ‘intuitive’ picture almost directly singles out the dominant stabilizing field line bending energy of the Alfvén waves and, consequently, concentrates on expansion schemes that minimize that contribution. This happens when the wave vector {{k}}0 of the perturbations, on average, is perpendicular to the magnetic field {B}. Hence, all macroscopic instabilities of tokamaks (kinks, interchanges, ballooning modes, ELMs, neoclassical tearing modes, etc) are characterized by satisfying the condition {{k}}0 \\perp {B}, or nearly so. In contrast, some of the major macroscopic instabilities of astrophysical plasmas (the Parker instability and the magneto-rotational instability) occur when precisely the opposite condition is satisfied: {{k}}0 \\parallel {B}. How do those instabilities escape from the dominance of the stabilizing Alfvén wave? The answer to that question involves, foremost, the recognition that MHD spectral theory of waves and instabilities of laboratory plasmas could be developed to such great depth since those plasmas are assumed to be in static equilibrium. This assumption is invalid for astrophysical plasmas where rotational and gravitational accelerations produce equilibria that are at best stationary, and the associated spectral theory is widely, and incorrectly, believed to be non-self adjoint. These complications are addressed, and cured, in the theory of the Spectral Web, recently developed by the author. Using this method, an extensive survey of instabilities of astrophysical plasmas demonstrates how the Alfvén wave is pushed into insignificance under these conditions to give rise to a host of instabilities that do not

  20. Frontiers in Sustainable Consumption Research

    DEFF Research Database (Denmark)

    Reisch, Lucia A.; Cohen, Maurie J.; Thøgersen, John B.

    2016-01-01

    While the field of sustainable consumption research is relatively young, it has already attracted scholars from all corners of the social sciences. The time has come to identify a new research agenda as trends in sustainable consumption research seem to suggest the dawning of a new phase. Not only...... does research need to be guided, but sustainable consumption policymaking, too, involving best practices around the application of standard and more innovative instruments....

  1. Frontiers in sustainable consumption research

    DEFF Research Database (Denmark)

    Reisch, Lucia A.; Cohen, Maurie J.; Thøgersen, John

    2016-01-01

    While the field of sustainable consumption research is relatively young, it has already attracted scholars from all corners of the social sciences. The time has come to identify a new research agenda as trends in sustainable consumption research seem to suggest the dawning of a new phase. Not only...... does research need to be guided, but sustainable consumption policymaking, too, involving best practices around the application of standard and more innovative instruments....

  2. Frontiers in relativistic celestial mechanics

    CERN Document Server

    2014-01-01

    Relativistic celestial mechanics – investigating the motion celestial bodies under the influence of general relativity – is a major tool of modern experimental gravitational physics. With a wide range of prominent authors from the field, this two-volume series consists of reviews on a multitude of advanced topics in the area of relativistic celestial mechanics – starting from more classical topics such as the regime of asymptotically-flat spacetime, light propagation and celestial ephemerides, but also including its role in cosmology and alternative theories of gravity as well as modern experiments in this area.

  3. 3D Global MHD Simulation of Titan's interaction with its surrounding plasma

    Science.gov (United States)

    Ma, Y.; Nagy, A. F.; Toth, G.; Najib, D.; Cravens, T. E.; Crary, F.; Coates, A. J.; Bertucci, C.; Neubauer, F. M.

    2006-12-01

    The interaction of Titan's ionosphere with its surrounding plasma flow is more complex than analogous solar wind-planet interactions, because of Titan's varying relative location in the Sun-Saturn system. We have studied the role of the angle between the direction of the solar radiation and the corotating plasma flow using our 3D multi-species MHD model. We also present results from a comparison between our model simulations and the observations corresponding to the T9 flyby of Cassini, using the measured upstream plasma parameters.

  4. Annual symposium on Frontiers in Science

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, N.; Fulton, K.R.

    1998-12-31

    This final report summarizes activities conducted for the National Academy of Sciences' Annual Symposium on Frontiers of Science with support from the US Department of Energy for the period July 1, 1993 through May 31, 1998. During the report period, five Frontiers of Science symposia were held at the Arnold and Mabel Beckman Center of the National Academies of Sciences and Engineering. For each Symposium, an organizing committee appointed by the NAS President selected and planned the eight sessions for the Symposium and identified general participants for invitation by the NAS President. These Symposia accomplished their goal of bringing together outstanding younger (age 45 or less) scientists to hear presentations in disciplines outside their own and to discuss exciting advances and opportunities in their fields in a format that encourages, and allows adequate time for, informal one-on-one discussions among participants. Of the 458 younger scientists who participated, over a quarter (124) were women. Participant lists for all symposia (1993--1997) are attached. The scientific participants were leaders in basic research from academic, industrial, and federal laboratories in such disciplines as astronomy, astrophysics, atmospheric science, biochemistry, cell biology, chemistry, computer science, earth sciences, engineering, genetics, material sciences, mathematics, microbiology, neuroscience, physics, and physiology. For each symposia, the 24 speakers and discussants on the program were urged to focus their presentations on current cutting-edge research in their field for a scientifically sophisticated but non-specialist audience, and to provide a sense of the experimental data--what is actually measured and seen in the various fields. They were also asked to address questions such as: What are the major research problems and unique tools in their field? What are the current limitations on advances as well as the frontiers? Speakers were asked to provide a

  5. Fermilab Computing at the Intensity Frontier

    Science.gov (United States)

    Fuess, S.; Gutsche, O.; Kirby, M.; Kutschke, R.; Lyon, A.; Norman, A.; Perdue, G.; Sexton-Kennedy, E.

    2015-12-01

    The Intensity Frontier refers to a diverse set of particle physics experiments using high- intensity beams. In this paper I will focus the discussion on the computing requirements and solutions of a set of neutrino and muon experiments in progress or planned to take place at the Fermi National Accelerator Laboratory located near Chicago, Illinois. The experiments face unique challenges, but also have overlapping computational needs. In principle, by exploiting the commonality and utilizing centralized computing tools and resources, requirements can be satisfied efficiently and scientists of individual experiments can focus more on the science and less on the development of tools and infrastructure.

  6. Frontiers in biomedical engineering and biotechnology.

    Science.gov (United States)

    Liu, Feng; Goodarzi, Ali; Wang, Haifeng; Stasiak, Joanna; Sun, Jianbo; Zhou, Yu

    2014-01-01

    The 2nd International Conference on Biomedical Engineering and Biotechnology (iCBEB 2013), held in Wuhan on 11–13 October 2013, is an annual conference that aims at providing an opportunity for international and national researchers and practitioners to present the most recent advances and future challenges in the fields of Biomedical Information, Biomedical Engineering and Biotechnology. The papers published by this issue are selected from this conference, which witnesses the frontier in the field of Biomedical Engineering and Biotechnology, which particularly has helped improving the level of clinical diagnosis in medical work.

  7. Mapping Frontier Research in the Humanities

    DEFF Research Database (Denmark)

    Knowledge production in academia today is burgeoning and increasingly interdisciplinary in nature. Research within the humanities is no exception: it is distributed across a variety of methodic styles of research and increasingly involves interactions with fields outside the narrow confines...... of the university. As a result, the notion of liberal arts and humanities within Western universities is undergoing profound transformations. In Mapping Frontier Research in the Humanities, the contributors explore this transformative process. What are the implications, both for the modes of research...... and for the organisation of the humanities and higher education?...

  8. CERN and the high energy frontier

    Directory of Open Access Journals (Sweden)

    Tsesmelis Emmanuel

    2014-04-01

    Full Text Available This paper presents the particle physics programme at CERN at the high-energy frontier. Starting from the key open questions in particle physics and the large-scale science facilities existing at CERN, concentrating on the Large Hadron Collider(LHC, this paper goes on to present future possibilities for global projects in high energy physics. The paper presents options for future colliders, all being within the framework of the recently updated European Strategy for Particle Physics, and all of which have a unique value to add to experimental particle physics. The paper concludes by outlining key messages for the way forward for high-energy physics research.

  9. Fermilab a laboratory at the frontier of research

    CERN Document Server

    Gillies, James D

    2002-01-01

    Since its foundation in 1967, creeping urbanization has taken away some of Fermilab's remoteness, but the famous buffalo still roam, and farm buildings evocative of frontier America dot the landscape - appropriately for a laboratory at the high-energy frontier of modern research. Topics discussed are the Tevatron, detector upgrades, the neutrino programme, Fermilab and the LHC and the non-accelerator programme.

  10. Challenges and Sustainability Practices of Frontier Schools in Montana

    Science.gov (United States)

    Morton, Claudette; Harmon, Hobart L.

    2011-01-01

    This article reports the findings of a study commissioned by the Montana Small Schools Alliance to explore the challenges and sustainability practices of frontier schools. A Montana frontier school is defined as a school district with 200 or fewer students with its attendant community located in a county with five or fewer people per square mile.…

  11. Molecular Mixology:the New Frontier for Cocktails

    OpenAIRE

    Murphy, James Peter

    2010-01-01

    A new frontier has emerged coined ‘molecular mixology’ that is continuing to radically transform cocktails across the globe, applying scientific analysis and techniques used in cooking and food processing to create a new frontier for cocktails works with spray foams, gels and atomisers to create unique cocktail textures and flavour experiences.

  12. A telecommunications intervention for frontier patients with diabetes.

    Science.gov (United States)

    Wagnild, Gail; MacCart, John G; Mitchell, Scot; Tyabah, Kiran; Leenknecht, Cindy; Meszaros, Jane Fitch

    2008-10-01

    The purpose of this study was to determine whether a telecommunications diabetes self-management (DSM) intervention would improve health-related outcomes among frontier participants with diabetes. A one-group pre-test/post-test quasi-experimental design with two groups of participants was used. Differences between pre and post-test periods on measures of physical and emotional health, knowledge of diabetes, and self-care behaviors were measured. Overall, participants did better along measures of blood pressure, HbA(1c), self-efficacy, knowledge of diabetes, understanding of DSM, monitoring behaviors, and reported less personal and social disruption from diabetes. Six-month follow-up results showed continued positive outcomes.

  13. Predesign of an experimental (5-10 MWt) disk MHD facility and prospects of commercial (1000 MWt) MHD/steam systems

    Science.gov (United States)

    Massee, P.; Degraaf, H. A. L.; Balemans, W. J. M.; Knoopers, H. G.; Tenkate, H. H. J.

    1990-10-01

    An experimental disk MHD (Magneto Hydro Dynamic) facility was designed. After designing the superconducting magnet for the open cycle disk MHD generator, the warm bore of the magnet was used as a constraint in designing the closed cycle disk MHD generator. In the experimental MHD facility an enthalpy extraction of 8.7 could be obtained with a 10 MWt open cycle MHD generator and 37.0 by means of a 5 MWt closed cycle MHD generator. System studies of four commercial scale MHD/steam systems were performed. The 1000 MWt open cycle disk generator leads to the smallest coal to busbar efficiency of 42.8. The highest coal to busbar efficiency of 50.0 is obtained in a commercial system with a closed cycle disk generator. The open cycle linear MHD/steam system leads to a coal to busbar efficiency of 49.4. When the details of the heat source and the required heat exchangers are considered, it can be anticipated that the system with an open cycle linear MHD generator will have the lowest cost of electricity (fl/kWh) of the four systems. The design of the superconducting magnet system for the experimental disk facility used principles that are valid also for large commercial systems. However, verification of these principles in an actual 1000 MWt superconducting magnet design needs further investigation.

  14. Research and development studies for MHD/coal power flow train components. Technical progress report, 1 September 1979-31 August 1980

    Energy Technology Data Exchange (ETDEWEB)

    Bloom, M. H.

    1980-01-01

    The aim of this program is to contribute to certain facets of the development of the MHD/coal power system, and particularly the CDIF of DOE with regard to its flow train. Consideration is given specifically to the electrical power take-off, the diagnostic and instrumentation systems, the combustor and MHD channel technology, and electrode alternatives. Within the constraints of the program, high priorities were assigned to the problems of power take-off and the related characteristics of the MHD channel, and to the establishment of a non-intrusive, laser-based diagnostic system. The next priority was given to the combustor modeling and to a significantly improved analysis of particle combustion. Separate abstracts were prepared for nine of the ten papers included. One paper was previously included in the data base. (WHK)

  15. Self-organized criticality in MHD driven plasma edge turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Santos Lima, G.Z. dos, E-mail: gzampier@ect.ufrn.br [Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, 59014-615, Natal, RN (Brazil); Iarosz, K.C.; Batista, A.M. [Programa de Pós-Graduação em Física, Universidade Estadual de Ponta Grossa, 84030-900, Ponta Grossa, PR (Brazil); Caldas, I.L. [Instituto de Física, Universidade de São Paulo, 05508-090, SP (Brazil); Guimarães-Filho, Z.O. [IIFS/PIIM, Université de Provence (France); Viana, R.L.; Lopes, S.R. [Departamento de Física, Universidade Federal do Paraná, 81531-990, Curitiba, PR (Brazil); Nascimento, I.C.; Kuznetsov, Yu.K. [Instituto de Física, Universidade de São Paulo, 05508-090, SP (Brazil)

    2012-01-16

    We analyze long-range time correlations and self-similar characteristics of the electrostatic turbulence at the plasma edge and scrape-off layer in the Tokamak Chauffage Alfvén Brésillien (TCABR), with low and high Magnetohydrodynamics (MHD) activity. We find evidence of self-organized criticality (SOC), mainly in the region near the tokamak limiter. Comparative analyses of data before and during the MHD activity reveals that during the high MHD activity the Hurst parameter decreases. Finally, we present a cellular automaton whose parameters are adjusted to simulate the analyzed turbulence SOC change with the MHD activity variation. -- Highlights: ► We analyze time correlations of the electrostatic turbulence in plasma. ► We study self-similar characteristics with low and high magnetohydrodynamics activity. ► We find evidence of self-organized criticality (SOC) behavior. ► SOC behavior is pronounced close to radial positions just after the limiter. ► We present a cellular automata that simulate the analyzed turbulence.

  16. 3D MHD Models of Active Region Loops

    Science.gov (United States)

    Ofman, Leon

    2004-01-01

    Present imaging and spectroscopic observations of active region loops allow to determine many physical parameters of the coronal loops, such as the density, temperature, velocity of flows in loops, and the magnetic field. However, due to projection effects many of these parameters remain ambiguous. Three dimensional imaging in EUV by the STEREO spacecraft will help to resolve the projection ambiguities, and the observations could be used to setup 3D MHD models of active region loops to study the dynamics and stability of active regions. Here the results of 3D MHD models of active region loops are presented, and the progress towards more realistic 3D MHD models of active regions. In particular the effects of impulsive events on the excitation of active region loop oscillations, and the generation, propagations and reflection of EIT waves are shown. It is shown how 3D MHD models together with 3D EUV observations can be used as a diagnostic tool for active region loop physical parameters, and to advance the science of the sources of solar coronal activity.

  17. ALEGRA-MHD Simulations for Magnetization of an Ellipsoidal Inclusion

    Science.gov (United States)

    2017-08-01

    electromagnetic phenomena including magnetohydrodynamics (MHD). This multiphysics capability is a key feature of ALEGRA and the result of many years of...and are the electric and magnetic field and magnetic induction, respectively; is the electric current density of...free charges, is the speed of light in vacuum, and is electrical conductivity. In the boundary conditions, and are

  18. MHD--Developing New Technology to Meet the Energy Crisis

    Science.gov (United States)

    Fitch, Sandra S.

    1978-01-01

    Magnetohydrodynamics is a technology that could utilize the nation's most abundant fossil fuel and produce electrical energy more efficiently and cleanly than present-day turbines. A national research and development program is ongoing in Butte, Montana at the Montana Energy and MHD Research and Development Institute (MERDI). (Author/RK)

  19. Heat transfer with thermal radiation on MHD particle–fluid ...

    Indian Academy of Sciences (India)

    2017-09-12

    Sep 12, 2017 ... In this article, effects of heat transfer on particle–fluid suspension induced by metachronal wave have been examined. The influence of magnetohydrodynamics (MHD) and thermal radiation are also taken into account with the help of Ohm's law and Roseland's approximation. The governing flow problem for ...

  20. Numerical analysis of MHD flow structure behind a square rod

    Energy Technology Data Exchange (ETDEWEB)

    Satake, M. [Advanced Fusion Reactor Engineering Laboratory, Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University (Japan)]. E-mail: msata@karma.qse.tohoku.ac.jp; Yuki, K. [Advanced Fusion Reactor Engineering Laboratory, Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University (Japan); Chiba, S. [Advanced Fusion Reactor Engineering Laboratory, Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University (Japan); Hashizume, H. [Advanced Fusion Reactor Engineering Laboratory, Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University (Japan)

    2006-02-15

    In a liquid blanket system, the large MHD pressure drop for liquid lithium and/or LiPb makes it difficult to remove high heat load. Since the MHD pressure drop is proportional to the flow velocity, it is necessary to remove the high heat load under low velocity conditions. Meanwhile, in case of molten salt Flibe, which is a high Prandtl number fluid, it is also important to enhance the heat transfer performance. In this study, MHD flow structure behind a square rod inserted in a parallel channel to enhance the heat transfer is simulated numerically to clarify the interaction between the flow structure and the magnetic field by using a low-Reynolds number k-{epsilon} turbulent model and including MHD effects. The laminar flow analysis indicates that the disappearance of twin vortices and the change of the Karman's vortex street to the twin vortices occur around a Ha/Re {sub h} ratio of 0.7 and 0.07-0.09, respectively. The turbulent flow analysis confirms that installing the rod near the heating wall contributes to enhancing the heat transfer even in the presence of a magnetic field, although the turbulent kinetic energy decreases with increasing Hartmann number.

  1. Standing Slow MHD Waves in Radiatively Cooling Coronal Loops

    Indian Academy of Sciences (India)

    In particular, the background plasma is assumed to be radiatively cooling. The effects of cooling on longitudinal slow MHD modes is analytically evaluated by choosing a simple form of radiative function, that ensures the temperature evolution of the background plasma due to radiation, coincides with the observed cooling ...

  2. Nonadiabatic interaction between a charged particle and an MHD pulse

    Directory of Open Access Journals (Sweden)

    Y. Kuramitsu

    2008-03-01

    Full Text Available Interaction between a magnetohydrodynamic~(MHD pulse and a charged particle is discussed both numerically and theoretically. Charged particles can be accelerated efficiently in the presence of spatially correlated MHD waves, such as short large amplitude magnetic structures, by successive mirror reflection (Fermi process. In order to understand this process, we study the reflection probability of particles by the MHD pulses, focusing on the adiabaticity on the particle motion. When the particle velocity is small (adiabatic regime, the probability that the particle is reflected by the MHD pulse is essentially determined only by the pitch angle, independent from the velocity. On the other hand, in the non-adiabatic regime, the reflection probability is inversely proportional to the square root of the normalized velocity. We discuss our numerical as well as analytical results of the interaction process with various pulse amplitude, pulse shape, and the pulse winding number. The reflection probability is universally represented as a power law function independent from above pulse properties.

  3. Thermosolutal MHD flow and radiative heat transfer with viscous ...

    African Journals Online (AJOL)

    This paper investigates double diffusive convection MHD flow past a vertical porous plate in a chemically active fluid with radiative heat transfer in the presence of viscous work and heat source. The resulting nonlinear dimensionless equations are solved by asymptotic analysis technique giving approximate analytic ...

  4. Unsteady MHD free convective flow past a vertical porous plate ...

    African Journals Online (AJOL)

    An attempt has been made to study the unsteady MHD free convective flow past a vertical porous plate immersed in a porous medium with Hall current, thermal diffusion and heat source. Analytical solution has been found depending on the physical parameters including the Hartmann number M, the Prandtl number Pr, the ...

  5. Effect of chemical reaction on unsteady MHD free convective two ...

    African Journals Online (AJOL)

    The effect of chemical reaction on unsteady MHD free convective two immiscible fluids flow has been studied. Approximate analytical solutions to the governing equations are found for the coupled and linear differential equations using regular perturbation method. Graphs depicting the effect of chemical reaction parameter ...

  6. Free convection effects and radiative heat transfer in MHD Stokes ...

    Indian Academy of Sciences (India)

    The present note deals with the effects of radiative heat transfer and free convection in MHD for a flow of an electrically conducting, incompressible, dusty viscous fluid past an impulsively started vertical non-conducting plate, under the influence of transversely applied magnetic field. The heat due to viscous dissipation and ...

  7. Unsteady MHD free convective flow past a vertical porous plate ...

    African Journals Online (AJOL)

    user

    been seen in MHD power generators, astrophysical and meteorological studies as well as in plasma physics. The Hall effect is due merely to ...... -3. Kg/ m ] fluid density in the boundary layer υ [ 2 -1. m s ] kinematic viscosity σ [ -1. -1. Ω m ] electrical conductivity θ [-] dimensionless temperature φ [. -3. Wm ] frictional heat. Ω [-].

  8. Numerical Calculation of the Output Power of a MHD Generator

    Directory of Open Access Journals (Sweden)

    Adrian CARABINEANU

    2014-12-01

    Full Text Available Using Lazăr Dragoş’s analytic solution for the electric potential we perform some numerical calculations in order to find the characteristics of a Faraday magnetohydrodymamics (MHD power generator (total power, useful power and Joule dissipation power.

  9. Generalized similarity method in unsteady two-dimensional MHD ...

    African Journals Online (AJOL)

    user

    this research was stimulated by two problems: protection of spacecrafts from aerodynamic overheating and destruction during the passage through dense atmosphere layers; building the operational ability of high temperature MHD generators constructive elements for direct transformation of heat energy in to electricity.

  10. Validation of MHD Models using MST RFP Plasmas

    Science.gov (United States)

    Jacobson, C. M.; Chapman, B. E.; den Hartog, D. J.; McCollam, K. J.; Sarff, J. S.; Sovinec, C. R.

    2017-10-01

    Rigorous validation of computational models used in fusion energy sciences over a large parameter space and across multiple magnetic configurations can increase confidence in their ability to predict the performance of future devices. MST is a well diagnosed reversed-field pinch (RFP) capable of operation with plasma current ranging from 60 kA to 500 kA. The resulting Lundquist number S, a key parameter in resistive magnetohydrodynamics (MHD), ranges from 4 ×104 to 8 ×106 for standard RFP plasmas and provides substantial overlap with MHD RFP simulations. MST RFP plasmas are simulated using both DEBS, a nonlinear single-fluid visco-resistive MHD code, and NIMROD, a nonlinear extended MHD code, with S ranging from 104 to 105 for single-fluid runs, and the magnetic Prandtl number Pm = 1 . Validation metric comparisons are presented, focusing on how normalized magnetic fluctuations at the edge b scale with S. Preliminary results for the dominant n = 6 mode are b S - 0 . 20 +/- 0 . 02 for single-fluid NIMROD, b S - 0 . 25 +/- 0 . 05 for DEBS, and b S - 0 . 20 +/- 0 . 02 for experimental measurements, however there is a significant discrepancy in mode amplitudes. Preliminary two-fluid NIMROD results are also presented. Work supported by US DOE.

  11. A high current density DC magnetohydrodynamic (MHD) micropump

    NARCIS (Netherlands)

    Homsy, Alexandra; Koster, Sander; Hogen-Koster, S.; Eijkel, Jan C.T.; van den Berg, Albert; Lucklum, F.; Verpoorte, E.; de Rooij, Nico F.

    2005-01-01

    This paper describes the working principle of a DC magnetohydrodynamic (MHD) micropump that can be operated at high DC current densities (J) in 75-µm-deep microfluidic channels without introducing gas bubbles into the pumping channel. The main design feature for current generation is a micromachined

  12. A high current density DC magnetohydrodynamic (MHD) micropump

    NARCIS (Netherlands)

    Homsy, A; Koster, Sander; Eijkel, JCT; van den Berg, A; Lucklum, F; Verpoorte, E; de Rooij, NF

    2005-01-01

    This paper describes the working principle of a DC magnetohydrodynamic (MHD) micropump that can be operated at high DC current densities (J) in 75-mu m-deep microfluidic channels without introducing gas bubbles into the pumping channel. The main design feature for current generation is a

  13. Combined effects of radiation and chemical reaction on MHD flow ...

    African Journals Online (AJOL)

    Dr Uday Singh Rajput is a faculty member in the department of mathematics and astronomy, Lucknow University, India. He has more than 25 years of teaching experience at UG and PG levels and also guided students for PhD degree. He has published more than 70 research articles. His research areas include MHD flows, ...

  14. Unsteady MHD flow in porous media past over exponentially ...

    African Journals Online (AJOL)

    published more than 60 research articles. His research areas include MHD flows, Graph Theory and Operations Research. . Gaurav Kumar is research student in the department of mathematics and astronomy, Lucknow University, India. Received April 2016. Accepted May 2016. Final acceptance in revised form May 2016.

  15. Unsteady MHD flow in porous media past over exponentially ...

    African Journals Online (AJOL)

    ... mass transfer along with Hall current. We have used Laplace-transform technique to find the solution of the equations in the flow model. The results obtained are discussed with the help of graphs. The drag force at the boundary has been tabulated. Keywords: MHD, unsteady flow, inclined plate, Hall current, skin friction ...

  16. System studies of coal fired-closed cycle MHD for central station power plants

    Science.gov (United States)

    Zauderer, B.

    1976-01-01

    This paper presents a discussion of the closed-cycle MHD results obtained in a recent study of various advanced energy-conversion power systems. The direct coal-fired MHD topping-steam bottoming cycle was established as the current choice for central station power generation. Emphasis is placed on the background assumptions and the conclusions that can be drawn from the closed-cycle MHD analysis. It is concluded that closed-cycle MHD has efficiencies comparable to that of open-cycle MHD. Its cost will possibly be slightly higher than that of the open-cycle MHD system. Also, with reasonable fuel escalation assumptions, both systems can produce lower-cost electricity than conventional steam power plants. Suggestions for further work in closed-cycle MHD components and systems are made.

  17. New frontiers in design synthesis.

    Science.gov (United States)

    Goldin, D S; Venneri, S L; Noor, A K

    1999-01-01

    The Intelligent Synthesis Environment (ISE), which is one of the major strategic technologies under development at NASA centers and the University of Virginia, is described. One of the major objectives of ISE is to significantly enhance the rapid creation of innovative affordable products and missions. ISE uses a synergistic combination of leading-edge technologies, including high performance computing, high capacity communications and networking, human-centered computing, knowledge-based engineering, computational intelligence, virtual product development, and product information management. The environment will link scientists, design teams, manufacturers, suppliers, and consultants who participate in the mission synthesis as well as in the creation and operation of the aerospace system. It will radically advance the process by which complex science missions are synthesized, and high-tech engineering Systems are designed, manufactured and operated. The five major components critical to ISE are human-centered computing, infrastructure for distributed collaboration, rapid synthesis and simulation tools, life cycle integration and validation, and cultural change in both the engineering and science creative process. The five components and their subelements are described. Related U.S. government programs are outlined and the future impact of ISE on engineering research and education is discussed.

  18. PROBLEMS OF FRONTIER ECONOMIC COOPERATION OF REPUBLIC DAGESTAN

    Directory of Open Access Journals (Sweden)

    A.R. Ramazanov

    2007-06-01

    Full Text Available From the beginning of 80th of XX century steady growth of scientific interest to a problematics of inter-regional trade and economic cooperation was observed in connection with formation of state frontiers and frontier areas. It is caused by development of some global processes in which frontier territories take the central place. In particular, growing lib-eralization of world trade promotes fast growth of external commodity circulation of the countries and development of the frontier areas providing international movements of the goods. Value of frontier inter-regional economic cooperation has increased in connection with globalization of economy, development of regional cooperation, cardinal changes on a politi-cal map of the world, tendencies to a deepening of democracy in social development.

  19. UTSI/CFFF MHD program completion and related activities

    Energy Technology Data Exchange (ETDEWEB)

    Muehlhauser, J.W.; Chapman, J.N.

    1999-04-30

    Maintenance work on the DOE CFFF facility remained in suspension for the entire quarter in accordance with the stop work order issued the previous quarter. Work resumed on the environmental restoration activities during the quarter and work performed is summarized. Progress continued on the five (5) high temperature superconductivity projects under Task 6. On the sol-gel process, improvement is reported in application of buffer layers to single crystals. Problems are discussed in applying buffer layers to nickel substrates. The status of cost performance studies is summarized. The status of diagnostic measurements directed toward real time control of manufacturing processes is reported with emphasis on measurement of surface smoothness. The results of atomic absorption measurement of MOCVD precursors are reported.

  20. Adding Drift Kinetics to a Global MHD Code

    Science.gov (United States)

    Lyon, J.; Merkin, V. G.; Zhang, B.; Ouellette, J.

    2015-12-01

    Global MHD models have generally been successful in describing thebehavior of the magnetosphere at large and meso-scales. An exceptionis the inner magnetosphere where energy dependent particle drifts areessential in the dynamics and evolution of the ring current. Even inthe tail particle drifts are a significant perturbation on the MHDbehavior of the plasma. The most common drift addition to MHD has beeninclusion of the Hall term in Faraday's Law. There have been attemptsin the space physics context to include gradient and curvature driftswithin a single fluid MHD picture. These have not been terriblysuccessful because the use of a single, Maxwellian distribution doesnot capture the energy dependent nature of the drifts. The advent ofmulti-fluid MHD codes leads to a reconsideration of this problem. TheVlasov equation can be used to define individual ``species'' whichcover a specific energy range. Each fluid can then be treated ashaving a separate evolution. We take the approach of the RiceConvection Model (RCM) that each energy channel can be described by adistribution that is essentially isotropic in the guiding centerpicture. In the local picture, this gives rise to drifts that can bedescribed in terms of the energy dependent inertial and diamagneticdrifts. By extending the MHD equations with these drifts we can get asystem which reduces to the RCM approach in the slow-flow innermagnetosphere but is not restricted to cases where the flow speed issmall. The restriction is that the equations can be expanded in theratio of the Larmor radius to the gradient scale lengths. At scalesapproaching di, the assumption of gyrotropic (or isotropic)distributions break down. In addition to the drifts, the formalism canalso be used to include finite Larmor radius effects on the pressuretensor (gyro-viscosity). We present some initial calculations with this method.

  1. Basins and new frontiers: an overview

    Energy Technology Data Exchange (ETDEWEB)

    Halbouty, M.T.

    1984-09-01

    Although the global transition to alternate energy sources has begun, for the coming decades the world's chief reliance will be on oil and natural gas supplies. Therefore, petroleum exploration must be concentrated toward discovering the oil and gas that lie untapped in both the known petroleum producing areas of the world and in the frontier regions. These frontier areas, the deserts, ice-covered lands, deep waters, and remote continental interiors, are estimated to hold vast hydrocarbons accumulations. It is in these sectors where future oil and gas discoveries could make the difference between a proper energy transition or a global catastrophe. Explorationists must reevaluate the mature and developing petroleum regions of the world. The vast ocean areas and the remote continental interiors must also be carefully and thoroughly appraised to ascertain their petroluem potential. In conjunction with these investigations, new and better uses of geology, geophysics, and petroleum engineering and technology must be employed so as to enhance not only exploration, but development and production.

  2. Study of high frequency MHD modes from ECE radiometer in Tore Supra

    Directory of Open Access Journals (Sweden)

    Dubuit N.

    2012-09-01

    Full Text Available Tore Supra ECE diagnostic has been recently upgraded to study MHD modes driven by energetic particles up to 400 kHz. To improve the measurement sensitivity, the ECE signals of the 32 channels radiometer were amplified just below the saturation limit and sources of noise were investigated in order to keep it as low as possible. With such an improvement, fast particle driven modes with frequencies up to 200 kHz were detected. A 4-channel correlation ECE system using YIG filters with tuneable frequency was also installed. It allows fine radial scans of MHD modes and correlation length measurements. For the two kinds of YIG filter in use, the minimum frequency separation between two ECE channels that could be achieved was established measuring the correlation coefficient between the respective radiation noises. Finally, by modelling the ECE radiometer taking into account the antenna radiation pattern and the vertical position of the ECE beam relative to the plasma centre we improved the data analysis tools, thus giving a better determination of the phase radial structure of ECE oscillations. The poloidal structure of MHD modes can then be identified from ECE data and, for off axis ECE lines of sight, the direction of the plasma rotation can also be determined. This method allows identifying the occurrence of an inverse cascade of electron fishbone modes ranging from m/n=4/4 to 1/1 (m and n are the poloidal and toroidal mode numbers, respectively which appears in lower hybrid current drive plasmas.

  3. Impact Of A Uniform Plasma Resistivity In MHD Modelling Of Helical Solutions For The Reversed Field Pinch Dynamo

    CERN Document Server

    Bonfiglio, D; Escande, D F

    2016-01-01

    Till now the magnetohydrodynamic (MHD) simulation of the reversed field pinch (RFP) has been performed by assuming axis-symmetric radial time independent dissipation profiles. In helical states this assumption is not correct since these dissipations should be flux functions, and should exhibit a helical symmetry as well. Therefore more correct simulations should incorporate self-consistent dissipation profiles. As a first step in this direction, the case of uniform dissipation profiles was considered by using the 3D nonlinear visco-resistive MHD code SpeCyl. It is found that a flattening of the resistivity profile results in the reduction of the dynamo action, which brings to marginally-reversed or even non-reversed equilibrium solutions. The physical origin of this result is discussed in relation to the electrostatic drift explanation of the RFP dynamo. This sets constraints on the functional choice of dissipations in future self-consistent simulations.

  4. Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Conceptual Design Engineering Report (CDER). Volume 4: Supplementary engineering data

    Science.gov (United States)

    1981-01-01

    The reference conceptual design of the Magnetohydrodynamic Engineering Test Facility (ETF), a prototype 200 MWe coal-fired electric generating plant designed to demonstrate the commercial feasibility of open cycle MHD is summarized. Main elements of the design are identified and explained, and the rationale behind them is reviewed. Major systems and plant facilities are listed and discussed. Construction cost and schedule estimates, and identification of engineering issues that should be reexamined are also given. The latest (1980-1981) information from the MHD technology program are integrated with the elements of a conventional steam power electric generating plant. Supplementary Engineering Data (Issues, Background, Performance Assurance Plan, Design Details, System Design Descriptions and Related Drawings) is presented.

  5. Fire, broadax and fever relieve: southeastern Brazil and the boost toward the agrarian frontiers in early 19th century

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Medeiros Lima

    2014-01-01

    Full Text Available In the beginning of the 19th century, discussions about malaria by some physicians and authorities who had acted in many Atlantic regions showed the idea that deforestation would impact positively on sanitation in Brazil. This was related to a boost - unknown until then - toward the agrarian frontiers at the expense of traditional forests and strongly marked by the rural endemics. It all happened in a time marked by the growth of the Brazilian free population, by the internalization of sugarcane farms - especially in São Paulo - by the coffee expansion, by the increase of agrarian frontier as a survival strategy for poverty, by the suppression of regulations for the settlements on vacant slots in 1822, and by the Atlantic recession in the second quarter of the 19th century. The dissemination of this conception can be evaluated based on data about migration to the agrarian frontier and the impact of malaria among free people.

  6. Experimental Facilities at the High Energy Frontier

    CERN Document Server

    Jenni, P.

    2016-01-01

    The main theme of the lectures covered the experimental work at hadron colliders, with a clear focus on the Large Hadron Collider (LHC) and on the roadmap that led finally to the discovery of the Higgs boson. The lectures were not a systematic course on machine and detector technologies, but rather tried to give a physics-motivated overview of many experimental aspects that were all relevant for making the discovery. The actual lectures covered a much broader scope than what is documented here in this write- up. The successful concepts for the experiments at the LHC have benefitted from the experience gained with previous generations of detectors at lower- energy machines. The lectures included also an outlook to the future experimental programme at the LHC, with its machine and experiments upgrades, as well as a short discussion of possible facilities at the high energy frontier beyond LHC.

  7. Research frontiers in the physical sciences

    Science.gov (United States)

    Thompson, J. M. T.

    2002-12-01

    As a prestigious generalist journal with a high scholarly reputation and a long influential history, the Philosophical Transactions of the Royal Society (Series A: Mathematical, Physical and Engineering Sciences), is an ideal vehicle for charting research frontiers across the physical sciences. It is the world's longest running scientific journal, and all issues since its foundation in 1665 are archived electronically by JSTOR in the USA (see http://www.jstor.org/) and are accessible through most university libraries. This archive gives facsimile access, and search facilities, to the works of many famous scientists. In this brief editorial I give first an introduction to the special Christmas issues by young scientists, followed by an overview of the fields covered.

  8. Geneva University: New frontiers on photodetection

    CERN Multimedia

    Université de Genève

    2012-01-01

    GENEVA UNIVERSITY Ecole de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92   Vendredi 17 février 2012 SEMINAIRE DE PHYSIQUE CORPUSCULAIRE 14h00 - Auditoire Stückelberg New frontiers on photodetection Dr Carla Aramo / INFN, Sezione di Napoli In the last years the use of new materials and new technologies opened the door to new kind of devices based on the coupling of well known properties of silicon with properties of other materials. In particular carbon material, in the form of carbon nanotubes, has been used to create heterojunction with interesting photoconductivity characteristics. The new photodetectors obtained show to have peculiar and interesting characteristics with quantum efficiency ranging from >35% to >15% in the investigated wavelength interval from near infrared to near ultraviolet region. The device character...

  9. Biomedical engineering frontier research and converging technologies

    CERN Document Server

    Jun, Ho-Wook; Shin, Jennifer; Lee, SangHoon

    2016-01-01

    This book provides readers with an integrative overview of the latest research and developments in the broad field of biomedical engineering. Each of the chapters offers a timely review written by leading biomedical engineers and aims at showing how the convergence of scientific and engineering fields with medicine has created a new basis for practically solving problems concerning human health, wellbeing and disease. While some of the latest frontiers of biomedicine, such as neuroscience and regenerative medicine, are becoming increasingly dependent on new ideas and tools from other disciplines, the paradigm shift caused by technological innovations in the fields of information science, nanotechnology, and robotics is opening new opportunities in healthcare, besides dramatically changing the ways we actually practice science. At the same time, a new generation of engineers, fluent in many different scientific “languages,” is creating entirely new fields of research that approach the “old” questions f...

  10. Frontiers International Conference on Wastewater Treatment

    CERN Document Server

    2017-01-01

    This book describes the latest research advances, innovations, and applications in the field of water management and environmental engineering as presented by leading researchers, engineers, life scientists and practitioners from around the world at the Frontiers International Conference on Wastewater Treatment (FICWTM), held in Palermo, Italy in May 2017. The topics covered are highly diverse and include the physical processes of mixing and dispersion, biological developments and mathematical modeling, such as computational fluid dynamics in wastewater, MBBR and hybrid systems, membrane bioreactors, anaerobic digestion, reduction of greenhouse gases from wastewater treatment plants, and energy optimization. The contributions amply demonstrate that the application of cost-effective technologies for waste treatment and control is urgently needed so as to implement appropriate regulatory measures that ensure pollution prevention and remediation, safeguard public health, and preserve the environment. The contrib...

  11. Frontiers of biomedical text mining: current progress

    Science.gov (United States)

    Zweigenbaum, Pierre; Demner-Fushman, Dina; Yu, Hong; Cohen, Kevin B.

    2008-01-01

    It is now almost 15 years since the publication of the first paper on text mining in the genomics domain, and decades since the first paper on text mining in the medical domain. Enormous progress has been made in the areas of information retrieval, evaluation methodologies and resource construction. Some problems, such as abbreviation-handling, can essentially be considered solved problems, and others, such as identification of gene mentions in text, seem likely to be solved soon. However, a number of problems at the frontiers of biomedical text mining continue to present interesting challenges and opportunities for great improvements and interesting research. In this article we review the current state of the art in biomedical text mining or ‘BioNLP’ in general, focusing primarily on papers published within the past year. PMID:17977867

  12. Status of the Proton Engineering Frontier Project

    CERN Document Server

    Choi Byung Ho

    2005-01-01

    The Proton Engineering Frontier Project (PEFP) approved and launched by the Korean government in July 2002 includes a 100MeV proton linear accelerator development and a program for its utilization. The first phase of the project, running from 2002 to 2005, was the design of a 100MeV proton linear accelerator and a part of development to 20 MeV. This consists of a 50 keV proton injector, a 3 MeV radio frequency quadrupole (RFQ), and a 20MeV drift tube linac (DTL). The 50 keV injector and the 3 MeV RFQ has been installed and tested, and the 20 MeV DTL is being assembled and tuned for beam tests. At the same time, the utilization programs using the proton beam have been planned, and some are now under way. The status and progress of the project are reported in detail.

  13. Mapping Frontier Research in the Humanities

    DEFF Research Database (Denmark)

    Whereas the classical sciences were organized around academic disciplines, knowledge production today is increasingly interdisciplinary and distributed across a variety of societal sectors. Classical disciplines have not only specialized and multiplied; they are increasingly interacting with extr...... in more complex landscapes of collective identities, networks, and constraints that open for new forms of intellectual leadership in the 21st century. Link: http://www.bloomsbury.com/uk/mapping-frontier-research-in-the-humanities-9781472597687/......-academic fields and supplemented by new transdisciplinary methods focusing on solving grand societal challenges, such as globalisation, multiculturalism, equality, democracy, security and health. Given the nature of these challenges and the ways in which university leadership has been organised, the very notion...

  14. Mapping Frontier Research in the Humanities

    DEFF Research Database (Denmark)

    of liberal arts and humanities within Western research universities is undergoing profound transformations. This book addresses the signatures of the transformative process in the humanities and the organisation of disciplinary knowledge. Based on multidimensional methodologies for mapping knowledge...... of impact and styles of reasoning, both in classical and interdisciplinary fields of the humanities. From this perspective, a more composite picture of human culture, language and history can emerge from humanities research. It goes beyond the picture of rational agents, and situates human interaction...... in more complex landscapes of collective identities, networks, and constraints that open for new forms of intellectual leadership in the 21st century. Link: http://www.bloomsbury.com/uk/mapping-frontier-research-in-the-humanities-9781472597687/...

  15. Africa: the new family planning frontier.

    Science.gov (United States)

    Caldwell, John C; Caldwell, Pat

    2002-03-01

    Sub-Saharan Africa will be the family planning frontier of the twenty-first century. Fertility levels and population growth rates are still high, and family planning programs suited to the region are still being developed. Nevertheless, by the end of the twentieth century, fertility transition was under way in Southern Africa and a few countries elsewhere. Successful regional family planning in the twenty-first century will depend upon stronger political leadership, the development of family planning programs that meet the needs of all segments of society and not only currently married women, assistance to the market, and a recognition of the central importance of hormonal methods, especially injectables. Problems include stagnation in economic growth and in child mortality decline, as well as the persistence of the AIDS epidemic.

  16. Mapping scientific frontiers : the quest for knowledge visualization.

    Energy Technology Data Exchange (ETDEWEB)

    Boyack, Kevin W.

    2003-08-01

    Visualization of scientific frontiers is a relatively new field, yet it has a long history and many predecessors. The application of science to science itself has been undertaken for decades with notable early contributions by Derek Price, Thomas Kuhn, Diana Crane, Eugene Garfield, and many others. What is new is the field of information visualization and application of its techniques to help us understand the process of science in the making. In his new book, Chaomei Chen takes us on a journey through this history, touching on predecessors, and then leading us firmly into the new world of Mapping Scientific Frontiers. Building on the foundation of his earlier book, Information Visualization and Virtual Environments, Chen's new offering is much less a tutorial in how to do information visualization, and much more a conceptual exploration of why and how the visualization of science can change the way we do science, amplified by real examples. Chen's stated intents for the book are: (1) to focus on principles of visual thinking that enable the identification of scientific frontiers; (2) to introduce a way to systematize the identification of scientific frontiers (or paradigms) through visualization techniques; and (3) to stimulate interdisciplinary research between information visualization and information science researchers. On all these counts, he succeeds. Chen's book can be broken into two parts which focus on the first two purposes stated above. The first, consisting of the initial four chapters, covers history and predecessors. Kuhn's theory of normal science punctuated by periods of revolution, now commonly known as paradigm shifts, motivates the work. Relevant predecessors outside the traditional field of information science such as cartography (both terrestrial and celestial), mapping the mind, and principles of visual association and communication, are given ample coverage. Chen also describes enabling techniques known to information

  17. Experimental study of the MHD activity associated to the mode m=2, n=1 in the Tore Supra tokamak; Etude experimentale de l`activite MHD associee au mode m=2, n=1 dans le tokamak Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Turlur, S.

    1996-09-20

    In tokamaks such as Tore Supra, the plasma confinement magnetic structure can be severely affected when Magnetohydrodynamic (M.H.D.) instabilities are destabilized. Experimentally, these instabilities are detected as magnetic fluctuations with captors located against the inner wall of the vacuum vessel. Fourier analysis provides amplitude, frequency and wave numbers of magnetic modes. In case of fast or transient phenomena, the analysis of magnetic fluctuations is completed using the singular value decomposition. In this dissertation, these analysis techniques are used to study two specific examples of M.H.D. activity related to the m = 2, n = 1 mode. On Tore Supra, the onset of this mode have strong consequences on the stability of partially or fully non inductive discharges. A regular and persistent sawtooth-like regime is observed on the electronic temperature leading to a significant degradation of the central confinement. Heat exhaust and particle balance are also essential parameters to achieve stationary discharges. On Tore Supra, these are studied with the ergodic divertor which produces stochastic magnetic field lines at the plasma edge. For optimal operating conditions of the ergodic divertor, the growth of the m = 2, N = 1 mode can lead to sudden destruction of magnetic equilibrium. For both cases, understanding and characterization of mechanisms leading to the observed m = 2, n = 1 M.H.D. activity are fundamental to obtain stationary discharges. (author). 115 refs.

  18. Strong MHD-intraction in hypersonic flows near bodies

    Science.gov (United States)

    Fomichev, Vladislav; Yadrenkin, Mikhail

    2017-10-01

    The results of experimental studies of local MHD interaction near bodies of various configurations are presented in the case when the work of the volumetric electromagnetic force leads to the deceleration of the hypersonic air flow, to the fixation of the ionization region in the flow, to the change of pressure in the interaction zone and to the appearance of a bow shock wave in front of the interaction zone. Shown, that at strong MHD-interaction the shape of the model slightly influences the final result of the change in the flow pattern, since the size of the interaction region becomes comparable, and in some cases larger than the size of the streamlined body.

  19. Kinetic Modifications to MHD Phenomena in Toroidal Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    C.Z. Cheng; N.N. Gorelenkov; G.J. Kramer; E. Fredrickson

    2004-09-03

    Particle kinetic effects involving small spatial and fast temporal scales can strongly affect MHD phenomena and the long time behavior of plasmas. In particular, kinetic effects such as finite ion gyroradii, trapped particle dynamics, and wave-particle resonances have been shown to greatly modify the stability of MHD modes. Here, the kinetic effects of trapped electron dynamics and finite ion gyroradii are shown to have a large stabilizing effect on kinetic ballooning modes in low aspect ratio toroidal plasmas such as NSTX [National Spherical Torus Experiment]. We also present the analysis of Toroidicity-induced Alfven Eigenmodes (TAEs) destabilized by fast neutral-beam injected ions in NSTX experiments and TAE stability in ITER due to alpha-particles and MeV negatively charged neutral beam injected ions.

  20. Divergence-free MHD Simulations with the HERACLES Code

    Directory of Open Access Journals (Sweden)

    Vides J.

    2013-12-01

    Full Text Available Numerical simulations of the magnetohydrodynamics (MHD equations have played a significant role in plasma research over the years. The need of obtaining physical and stable solutions to these equations has led to the development of several schemes, all requiring to satisfy and preserve the divergence constraint of the magnetic field numerically. In this paper, we aim to show the importance of maintaining this constraint numerically. We investigate in particular the hyperbolic divergence cleaning technique applied to the ideal MHD equations on a collocated grid and compare it to the constrained transport technique that uses a staggered grid to maintain the property. The methods are implemented in the software HERACLES and several numerical tests are presented, where the robustness and accuracy of the different schemes can be directly compared.

  1. FOI-PERFECT code: 3D relaxation MHD modeling and Applications

    Science.gov (United States)

    Wang, Gang-Hua; Duan, Shu-Chao; Comutational Physics Team Team

    2016-10-01

    One of the challenges in numerical simulations of electromagnetically driven high energy density (HED) systems is the existence of vacuum region. FOI-PERFECT code adopts a full relaxation magnetohydrodynamic (MHD) model. The electromagnetic part of the conventional model adopts the magnetic diffusion approximation. The vacuum region is approximated by artificially increasing the resistivity. On one hand the phase/group velocity is superluminal and hence non-physical in the vacuum region, on the other hand a diffusion equation with large diffusion coefficient can only be solved by implicit scheme which is difficult to be parallelized and converge. A better alternative is to solve the full electromagnetic equations. Maxwell's equations coupled with the constitutive equation, generalized Ohm's law, constitute a relaxation model. The dispersion relation is given to show its transition from electromagnetic propagation in vacuum to resistive MHD in plasma in a natural way. The phase and group velocities are finite for this system. A better time stepping is adopted to give a 3rd full order convergence in time domain without the stiff relaxation term restriction. Therefore it is convenient for explicit & parallel computations. Some numerical results of FOI-PERFECT code are also given. Project supported by the National Natural Science Foundation of China (Grant No. 11571293) And Foundation of China Academy of Engineering Physics (Grant No. 2015B0201023).

  2. Real-time diagnostics at ASDEX Upgrade-Integration with MHD feedback control

    Energy Technology Data Exchange (ETDEWEB)

    Treutterer, W. [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstrasse 2, D-85748 Garching (Germany)], E-mail: Wolfgang.Treutterer@ipp.mpg.de; Behler, K.; Giannone, L.; Hicks, N.; Manini, A.; Maraschek, M.; Raupp, G.; Reich, M.; Sips, A.C.C.; Stober, J.; Suttrop, W. [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstrasse 2, D-85748 Garching (Germany)

    2008-04-15

    At the ASDEX Upgrade tokamak experiment, a new feedback control loop is under construction with the aim of stabilizing magneto-hydrodynamic (MHD) instabilities, such as neoclassical tearing modes and sawteeth. It uses the mirrors of the electron cyclotron heating (ECH) launchers, which can be steered in real-time to guide each beam to the position needed to stabilize and suppress the mode. The control system needs highly specialized plasma state information such as island position and ECH beam deposition locations in real-time. Data from several diagnostic systems, like electron cyclotron emission (ECE), magnetic measurements and motional Stark effect must be combined in real-time to obtain the required information. These systems strongly differ in sampling characteristics and time resolutions. High sampling rates as 2 MHz for ECE are often required to provide enough data for correlation or frequency analysis. On the other hand, complex analysis methods, such as equilibrium and profile reconstruction, may operate on slower rates of some milliseconds and need tight interaction with measurement systems and high computing power. In this paper, we describe a concept for distributed real-time diagnostic data handling, integration of data from several asynchronous diagnostic systems, and connection to the discharge control system for a broad spectrum of requirements. The system is structured into distributed diagnostic computer clusters, a real-time signal server to combine all information, and the discharge control system. While the focus is currently on MHD control, further real-time diagnostic related applications will be added in future.

  3. Flow of MHD Carreau Fluid in a Curved Channel

    Directory of Open Access Journals (Sweden)

    Saima Noreen

    2013-01-01

    Full Text Available Analysis has been made for the curvature effects on the MHD peristaltic flow of an incompressible Carreau fluid in a channel. The flow problem is first reduced in the wave frame of reference and then solved after employing the long wavelength and low Reynolds number approximations. Expressions of stream function, pressure gradient, magnetic force function, induced magnetic field and current density are derived and then examined for various parameters of interest.

  4. Solar-Driven Liquid-Metal MHD Generator

    Science.gov (United States)

    Hohl, F.; Lee, J. H.

    1982-01-01

    Liquid-metal magnetohydrodynamic (MHD) power generator with solar oven as its heat source has potential to produce electric power in space and on Earth at high efficiency. Generator focuses radiation from Sun to heat driving gas that pushes liquid metal past magnetic coil. Power is extracted directly from electric currents set up in conducting liquid. Using solar energy as fuel can save considerable costs and payload weight, compared to previous systems.

  5. MHD Stability of Polar Caps of Accreting Neutron Stars

    Science.gov (United States)

    Litwin, C.; Brown, E. F.; Rosner, R.

    2000-12-01

    We assess the stability of magnetic Rayleigh-Taylor type modes driven by the overpressure of magnetically confined accreted matter on the surface of a neutron star. We employ the magnetohydrodynamic (MHD) energy principle to analyze the stability of short-wavelength (ballooning) modes subject to line-tying in the neutron star crust. Research supported by ASCI/Alliances Center for Astrophysical Thermonuclear Flashes at the University of Chicago.

  6. MHD generator with improved network coupling electrodes to a load

    Science.gov (United States)

    Rosa, Richard J.

    1977-01-01

    An MHD generator has a plurality of segmented electrodes extending longitudinally of a duct, whereby progressively increasing high DC voltages are derived from a set of cathode electrodes and progressively increasing low DC voltages are derived from a set of anode electrodes. First and second load terminals are respectively connected to the cathode and anode electrodes by separate coupling networks, each of which includes a number of SCR's and a number of diode rectifiers.

  7. The Nonlinear Magnetosphere: Expressions in MHD and in Kinetic Models

    Science.gov (United States)

    Hesse, Michael; Birn, Joachim

    2011-01-01

    Like most plasma systems, the magnetosphere of the Earth is governed by nonlinear dynamic evolution equations. The impact of nonlinearities ranges from large scales, where overall dynamics features are exhibiting nonlinear behavior, to small scale, kinetic, processes, where nonlinear behavior governs, among others, energy conversion and dissipation. In this talk we present a select set of examples of such behavior, with a specific emphasis on how nonlinear effects manifest themselves in MHD and in kinetic models of magnetospheric plasma dynamics.

  8. Intermittency in MHD turbulence and coronal nanoflares modelling

    Directory of Open Access Journals (Sweden)

    P. Veltri

    2005-01-01

    Full Text Available High resolution numerical simulations, solar wind data analysis, and measurements at the edges of laboratory plasma devices have allowed for a huge progress in our understanding of MHD turbulence. The high resolution of solar wind measurements has allowed to characterize the intermittency observed at small scales. We are now able to set up a consistent and convincing view of the main properties of MHD turbulence, which in turn constitutes an extremely efficient tool in understanding the behaviour of turbulent plasmas, like those in solar corona, where in situ observations are not available. Using this knowledge a model to describe injection, due to foot-point motions, storage and dissipation of MHD turbulence in coronal loops, is built where we assume strong longitudinal magnetic field, low beta and high aspect ratio, which allows us to use the set of reduced MHD equations (RMHD. The model is based on a shell technique in the wave vector space orthogonal to the strong magnetic field, while the dependence on the longitudinal coordinate is preserved. Numerical simulations show that injected energy is efficiently stored in the loop where a significant level of magnetic and velocity fluctuations is obtained. Nonlinear interactions give rise to an energy cascade towards smaller scales where energy is dissipated in an intermittent fashion. Due to the strong longitudinal magnetic field, dissipative structures propagate along the loop, with the typical speed of the Alfvén waves. The statistical analysis on the intermittent dissipative events compares well with all observed properties of nanoflare emission statistics. Moreover the recent observations of non thermal velocity measurements during flare occurrence are well described by the numerical results of the simulation model. All these results naturally emerge from the model dynamical evolution without any need of an ad-hoc hypothesis.

  9. MHD considerations for a self-cooled liquid lithium blanket

    Energy Technology Data Exchange (ETDEWEB)

    Sze, D.K.; Mattas, R.F.; Hull, A.B.; Picologlou, B.F.; Smith, D.L.

    1992-03-01

    The magnetohydrodynamic (MHD) effects can present a feasibility issue for a self-cooled liquid metal blanket of magnetically confined fusion reactors, especially inboard regime of a tokamak. This pressure drop can be significantly reduced by using insulated wall structure. A self-healing insulating coating has been identified, which will reduce the pressure drop by more than a factor of 10. The future research direction to further quantify the performance of this coating is also outlined.

  10. MHD Advanced Power Train Phase I, Final Report, Volume 7

    Energy Technology Data Exchange (ETDEWEB)

    A. R. Jones

    1985-08-01

    This appendix provides additional data in support of the MHD/Steam Power Plant Analyses reported in report Volume 5. The data is in the form of 3PA/SUMARY computer code printouts. The order of presentation in all four cases is as follows: (1) Overall Performance; (2) Component/Subsystem Information; (3) Plant Cost Accounts Summary; and (4) Plant Costing Details and Cost of Electricity.

  11. Travelling Through a Sea of Poppies: from the Geographical to the Cultural Frontier

    Directory of Open Access Journals (Sweden)

    Elisabetta Zurru

    2011-05-01

    Full Text Available The paper focuses on the relation between the concepts of geographical and cultural frontiers, using Sea of Poppies (2008, Amitav Ghosh’s last novel, as a case study. Indeed, the journey of the ship Ibis from the Gulf of Bengal to the Mauritius islands provides the backdrop against which the theme of the crossing of religious, social and caste boundaries is developed: as the Ibis crosses the frontier which divides India from the Mauritius, the men and women on board, embodiments of both colonizing and colonized values, are subjected to a series of (religious, linguistic, social negotiation processes. The aim of the paper will be to analyze some of these processes in order to show that in the novel negotiation and contamination become synonymic with cultural resource and new beginnings.

  12. Nonlinear MHD simulations of QH-mode DIII-D plasmas and implications for ITER high Q scenarios

    Science.gov (United States)

    Liu, F.; Huijsmans, G. T. A.; Loarte, A.; Garofalo, A. M.; Solomon, W. M.; Hoelzl, M.; Nkonga, B.; Pamela, S.; Becoulet, M.; Orain, F.; Van Vugt, D.

    2018-01-01

    In nonlinear MHD simulations of DIII-D QH-mode plasmas it has been found that low n kink/peeling modes (KPMs) are unstable and grow to a saturated kink-peeling mode. The features of the dominant saturated KPMs, which are localised toroidally by nonlinear coupling of harmonics, such as mode frequencies, density fluctuations and their effect on pedestal particle and energy transport, are in good agreement with the observations of the edge harmonic oscillation typically present in DIII-D QH-mode experiments. The nonlinear evolution of MHD modes including both kink-peeling modes and ballooning modes, is investigated through MHD simulations by varying the pedestal current and pressure relative to the initial conditions of DIII-D QH-mode plasma. The edge current and pressure at the pedestal are key parameters for the plasma either saturating to a QH-mode regime or a ballooning mode dominant regime. The influence of E × B flow and its shear on the QH-mode plasma has been investigated. E × B flow shear has a strong stabilisation effect on the medium to high-n modes but is destabilising for the n = 2 mode. The QH-mode extrapolation results of an ITER Q = 10 plasma show that the pedestal currents are large enough to destabilise n = 1–5 KPMs, leading to a stationary saturated kink-peeling mode.

  13. MHD magnet technology development program summary, September 1982

    Energy Technology Data Exchange (ETDEWEB)

    1983-11-01

    The program of MHD magnet technology development conducted for the US Department of Energy by the Massachusetts Institute of Technology during the past five years is summarized. The general strategy is explained, the various parts of the program are described and the results are discussed. Subjects covered include component analysis, research and development aimed at improving the technology base, preparation of reference designs for commercial-scale magnets with associated design evaluations, manufacturability studies and cost estimations, the detail design and procurement of MHD test facility magnets involving transfer of technology to industry, investigations of accessory subsystem characteristics and magnet-flow-train interfacing considerations and the establishment of tentative recommendations for design standards, quality assurance procedures and safety procedures. A systematic approach (framework) developed to aid in the selection of the most suitable commercial-scale magnet designs is presented and the program status as of September 1982 is reported. Recommendations are made for future work needed to complete the design evaluation and selection process and to provide a sound technological base for the detail design and construction of commercial-scale MHD magnets. 85 references.

  14. Spectral slope and Kolmogorov constant of MHD turbulence.

    Science.gov (United States)

    Beresnyak, A

    2011-02-18

    The spectral slope of strong MHD turbulence has recently been a matter of controversy. While the Goldreich-Sridhar model predicts a -5/3 slope, shallower slopes have been observed in numerics. We argue that earlier numerics were affected by driving due to a diffuse locality of energy transfer. Our highest-resolution simulation (3072(2)×1024) exhibited the asymptotic -5/3 scaling. We also discover that the dynamic alignment, proposed in models with -3/2 slope, saturates and cannot modify the asymptotic, high Reynolds number slope. From the observed -5/3 scaling we measure the Kolmogorov constant C(KA)=3.27±0.07 for Alfvénic turbulence and C(K)=4.2±0.2 for full MHD turbulence, which is higher than the hydrodynamic value of 1.64. This larger C(K) indicates inefficient energy transfer in MHD turbulence, which is in agreement with diffuse locality.

  15. Magnus: A New Resistive MHD Code with Heat Flow Terms

    Science.gov (United States)

    Navarro, Anamaría; Lora-Clavijo, F. D.; González, Guillermo A.

    2017-07-01

    We present a new magnetohydrodynamic (MHD) code for the simulation of wave propagation in the solar atmosphere, under the effects of electrical resistivity—but not dominant—and heat transference in a uniform 3D grid. The code is based on the finite-volume method combined with the HLLE and HLLC approximate Riemann solvers, which use different slope limiters like MINMOD, MC, and WENO5. In order to control the growth of the divergence of the magnetic field, due to numerical errors, we apply the Flux Constrained Transport method, which is described in detail to understand how the resistive terms are included in the algorithm. In our results, it is verified that this method preserves the divergence of the magnetic fields within the machine round-off error (˜ 1× {10}-12). For the validation of the accuracy and efficiency of the schemes implemented in the code, we present some numerical tests in 1D and 2D for the ideal MHD. Later, we show one test for the resistivity in a magnetic reconnection process and one for the thermal conduction, where the temperature is advected by the magnetic field lines. Moreover, we display two numerical problems associated with the MHD wave propagation. The first one corresponds to a 3D evolution of a vertical velocity pulse at the photosphere-transition-corona region, while the second one consists of a 2D simulation of a transverse velocity pulse in a coronal loop.

  16. Relaxed MHD equilibria inside 3D shaped conducting surfaces

    Science.gov (United States)

    Hassam, A.; Tenbarge, J.; Dorland, W.; Landreman, M.; Sengupta, W.

    2017-10-01

    A 3D nonlinear dissipative MHD code is developed to allow relaxation to low-beta MHD equilibrium inside a shaped 3D conducting boundary with prescribed conserved axial magnetic flux and no external current. Formation of magnetic islands is allowed. Heat sources would be eventually introduced to allow possible non-stationary convection depending on the MHD stability properties. The initial development is done using UMHD (Guzdar et al., PF, 1993). A primary objective is to minimize numerical boundary noise. In particular, codes which specify the normal magnetic field B.n on bounding surfaces are prone to boundary noise generation. We shape the boundary to conform to the desired field shape so that B.n is zero on the boundary, employing curvilinear coordinates. Significant noise reduction has been achieved by this approach. Boundary noise is strongly suppressed if the boundary is modeled as a sharp ramp-down in resistivity, allowing relaxation to equilibrium but no penetration into the low resistivity region. Initial results have been verified w.r.t. analytic calculation in the weak shaping limit. A rotational transform is observed in helical shaping. Relaxed equilibria inside helically symmetric conducting boundaries will be presented.

  17. Control of MHD instabilities in the STOR-M tokamak

    Science.gov (United States)

    Xiao, Chijin; Elgriw, Sayf; Hirose, Akira; STOR-M Team

    2011-10-01

    Experiments to control the MHD activities have been carried out through compact torus injection (CTI) and resonant helical coils (RHC) on the STOR-M tokamak. The MHD instabilities have been measured by Mirnov coil arrays and miniature soft X-ray (SXR) pin-hole cameras. The data have been analyzed by singular value decomposition algorithm and the spatial Fourier harmonic analysis. Injection of a high density compact torus into STOR-M induced a transient phase with reduced m = 2 Mirnov oscillation amplitude. After appearance of an m = 1 gong mode burst the m = 2 oscillation amplitude returned to its nominal level before CTI. In the RHC experiments, an m = 2 helical coil was wound outside the vacuum chamber and powered by a capacitor bank through an IGBT switch. A current pulse of a few milliseconds was applied to RHC during the plasma current plateau. Once the current amplitude reaches a threshold level, the m = 2 MHD oscillation level was significantly reduced. Addition of equilibrium poloidal magnetic field calculated by TOSCA code, an assumed magnetic island perturbation, and the vacuum magnetic field produced by RHC also showed that the island can be eliminated when the RHC current reached a certain level. NSERC and the Canada Research Chair Program

  18. The computation of resistive MHD instabilities in axisymmetric toroidal plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Harley, T.R.; Cheng, C.Z.; Jardin, S.C.

    1991-03-01

    We describe the linear MHD eigenmode code NOVA-R, which calculates the resistive stability of axisymmetric toroidal equilibria. A formulation has been adopted which accurately resolves the continuum spectrum of the ideal MHD operator. The resistive MHD stability equations are transformed into three coupled second order equations, one of which recovers the equation solved by the NOVA code in the ideal limit. The eigenfunctions are represented by a Fourier expansion and cubic B-spline finite elements which are packed about the internal boundary layer. Accurate results are presented for dimensionless resistivities as low as 10{sup {minus}30} in cylindrical geometry. For axisymmetric toroidal plasmas we demonstrate the accuracy of the NOVA-R code by recovering ideal results in the {eta} {yields} 0 limit, and cylindrical resistive interchange results in the a/R {yields} limit. {Delta}{prime} analysis performed using the eigenfunctions computed by the NOVA-R code agree with the asymptotic matching results from the resistive PEST code for zero beta equilibria. 33 refs., 30 figs.

  19. Current Generation in Extragalactic Jets by MHD Waves

    Science.gov (United States)

    Jafelice, L. C.; Opher, R.; de Assis, A. S.; Busnardo-Neto, J.

    1990-11-01

    ABSTRACT: Several observations indicate that strong extragalactic jets (EJ) appear to need magnetically aided confinement in order for the total (kinetic plus magnetic) external pressure to balance the jet total internal pressure. On the other hand, the motion of highly ionized EJ in a magnetic field is, in general, expected to excite MHD waves on the borders of EJ by the Kelvin-Helmholtz instability. We study transit-titne magnetic damping of magnetosonic and surface waves in these essentially collisionless plasmas, and show that these low-frequency compressiveNHi) waves produce appreciable electric currents, I,which can be dynamically important. Using indicated values from observations of strong EJ, we obtain for 2= 2c % lO-10, where I is the current required for confining these jets and EIB /BoI c5 the MHD perturbation level, with B (Bo) being the MHD wave background) magnetic field. We suggest that c may be self-regulating, perturbations > Qchoking-off the jet, requiring to return to c The model has also the advantage of admitting a distributed generator which acts along the jet length and avoids problems of previous models requiring a current generator at the galactic nucleus to maintain a huge circuit with length % EJ length. : GALAXIES-JETS - HYDROHAGNETICS

  20. Parametric analysis of closed cycle magnetohydrodynamic (MHD) power plants

    Science.gov (United States)

    Owens, W.; Berg, R.; Murthy, R.; Patten, J.

    1981-01-01

    A parametric analysis of closed cycle MHD power plants was performed which studied the technical feasibility, associated capital cost, and cost of electricity for the direct combustion of coal or coal derived fuel. Three reference plants, differing primarily in the method of coal conversion utilized, were defined. Reference Plant 1 used direct coal fired combustion while Reference Plants 2 and 3 employed on site integrated gasifiers. Reference Plant 2 used a pressurized gasifier while Reference Plant 3 used a ""state of the art' atmospheric gasifier. Thirty plant configurations were considered by using parametric variations from the Reference Plants. Parametric variations include the type of coal (Montana Rosebud or Illinois No. 6), clean up systems (hot or cold gas clean up), on or two stage atmospheric or pressurized direct fired coal combustors, and six different gasifier systems. Plant sizes ranged from 100 to 1000 MWe. Overall plant performance was calculated using two methodologies. In one task, the channel performance was assumed and the MHD topping cycle efficiencies were based on the assumed values. A second task involved rigorous calculations of channel performance (enthalpy extraction, isentropic efficiency and generator output) that verified the original (task one) assumptions. Closed cycle MHD capital costs were estimated for the task one plants; task two cost estimates were made for the channel and magnet only.

  1. Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant Conceptual Design Engineering Report (CDER)

    Science.gov (United States)

    1981-01-01

    The reference conceptual design of the magnetohydrodynamic (MHD) Engineering Test Facility (ETF), a prototype 200 MWe coal-fired electric generating plant designed to demonstrate the commercial feasibility of open cycle MHD, is summarized. Main elements of the design, systems, and plant facilities are illustrated. System design descriptions are included for closed cycle cooling water, industrial gas systems, fuel oil, boiler flue gas, coal management, seed management, slag management, plant industrial waste, fire service water, oxidant supply, MHD power ventilating

  2. Interpreting New Data from the High Energy Frontier

    Energy Technology Data Exchange (ETDEWEB)

    Thaler, Jesse [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2016-09-26

    This is the final technical report for DOE grant DE-SC0006389, "Interpreting New Data from the High Energy Frontier", describing research accomplishments by the PI in the field of theoretical high energy physics.

  3. The First Half Billion Years: Results from the Frontier Fields

    Science.gov (United States)

    Coe, Dan; Bradley, Larry; Zitrin, Adi

    2015-08-01

    The Frontier Fields program is transforming our understanding of galaxy evolution in the first 550 million years (z > 9). Where previous programs yielded perhaps a dozen z > 9 candidates, we estimate the Frontier Fields may yield up to ~70 (~6 per field). The first Frontier Fields images yielded strong z ~ 8 and 9 candidates, but fewer than expected at z > 9 (including one triply-imaged z ~ 10 candidate). By the time of this meeting, Hubble and Spitzer will have completed deep Frontier Fields imaging of the first four pairs of new "blank" fields and nearby fields strongly lensed by galaxy clusters. In this talk, I will present our latest high-redshift candidates, constraints on high-redshift luminosity functions, and implications for reionization. I will discuss whether the deficit of faint z > 9 galaxies persists (as also found in the UDF) and how incompleteness may be affecting our results.

  4. Review: Gerald Monsman, Rider Haggard on the Imperial Frontier ...

    African Journals Online (AJOL)

    Abstract. Gerald Monsman,. Rider Haggard on the Imperial Frontier, The Political and Literary Contexts of His African Romances (Greensboro, ELT Press 2006), ix + 294pp., paperback, ISBN 0 944318 21 5.

  5. Fifth German-American Frontiers of Engineering Symposium

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-05-01

    The agenda book for the Fifth German-American Frontiers of Engineering Symposium contains abstracts of the 16 presentations as well as information on the program, bios of the speakers, contact information for all attendees, and background on the activity.

  6. Venus Origins Explorer (VOX), a Proposed New Frontier Mission

    Science.gov (United States)

    Smrekar, S. E.; Dyar, M. D.; Hensley, S.; Helbert, J.; Sotin, C.; Mazarico, E.; VOX Team

    2017-11-01

    VOX’s new methods provide global mineralogy, high-resolution topography and radar imaging plus surface deformation. VOX exceeds New Frontiers science objectives from orbit, with essential surface reconnaissance and in-situ noble gas measurements.

  7. Report of results of contract research. 'Research on magneto hydrodynamic (MHD) generation'; MHD hatsuden system no kenkyu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1980-03-01

    Examination was conducted in detail on an MHD generation system by coal combustion, with the results reported. Concerning a gas table calculation program in coal combustion, it was prepared assuming 100% slag removal ratio in the combustor as the primary approximation. A combustor for MHD generation needs to efficiently burn fuel using high temperature pre-heated air as the oxidant, to fully dissociate/electrolytically dissociate seed, and to supply to the generation channel a high speed combustion gas plasma having a high electrical conductivity which is required for MHD generation. This year, an examination was conducted on technological problems in burning coal in an MHD combustor. As for the NOx elimination system in an MHD generation plant, an examination was made if the method studied so far in MHD generation using heavy oil as the fuel is applicable to coal. Also investigated and reviewed were various characteristics, change in physical properties, recovery method, etc., in a mixed state of seed and slag in the case of coal combustion MHD. (NEDO)

  8. Measuring the Efficiency of a Hospital based on the Econometric Stochastic Frontier Analysis (SFA) Method.

    Science.gov (United States)

    Rezaei, Satar; Zandian, Hamed; Baniasadi, Akram; Moghadam, Telma Zahirian; Delavari, Somayeh; Delavari, Sajad

    2016-02-01

    Hospitals are the most expensive health services provider in the world. Therefore, the evaluation of their performance can be used to reduce costs. The aim of this study was to determine the efficiency of the hospitals at the Kurdistan University of Medical Sciences using stochastic frontier analysis (SFA). This was a cross-sectional and retrospective study that assessed the performance of Kurdistan teaching hospitals (n = 12) between 2007 and 2013. The Stochastic Frontier Analysis method was used to achieve this aim. The numbers of active beds, nurses, physicians, and other staff members were considered as input variables, while the inpatient admission was considered as the output. The data were analyzed using Frontier 4.1 software. The mean technical efficiency of the hospitals we studied was 0.67. The results of the Cobb-Douglas production function showed that the maximum elasticity was related to the active beds and the elasticity of nurses was negative. Also, the return to scale was increasing. The results of this study indicated that the performances of the hospitals were not appropriate in terms of technical efficiency. In addition, there was a capacity enhancement of the output of the hospitals, compared with the most efficient hospitals studied, of about33%. It is suggested that the effect of various factors, such as the quality of health care and the patients' satisfaction, be considered in the future studies to assess hospitals' performances.

  9. European regional efficiency and geographical externalities: a spatial nonparametric frontier analysis

    Science.gov (United States)

    Ramajo, Julián; Cordero, José Manuel; Márquez, Miguel Ángel

    2017-10-01

    This paper analyses region-level technical efficiency in nine European countries over the 1995-2007 period. We propose the application of a nonparametric conditional frontier approach to account for the presence of heterogeneous conditions in the form of geographical externalities. Such environmental factors are beyond the control of regional authorities, but may affect the production function. Therefore, they need to be considered in the frontier estimation. Specifically, a spatial autoregressive term is included as an external conditioning factor in a robust order- m model. Thus we can test the hypothesis of non-separability (the external factor impacts both the input-output space and the distribution of efficiencies), demonstrating the existence of significant global interregional spillovers into the production process. Our findings show that geographical externalities affect both the frontier level and the probability of being more or less efficient. Specifically, the results support the fact that the spatial lag variable has an inverted U-shaped non-linear impact on the performance of regions. This finding can be interpreted as a differential effect of interregional spillovers depending on the size of the neighboring economies: positive externalities for small values, possibly related to agglomeration economies, and negative externalities for high values, indicating the possibility of production congestion. Additionally, evidence of the existence of a strong geographic pattern of European regional efficiency is reported and the levels of technical efficiency are acknowledged to have converged during the period under analysis.

  10. Damping of Linear Nonadiabatic MHD Waves in a Flowing Prominence Medium

    Directory of Open Access Journals (Sweden)

    Nagendra Kumar

    2014-01-01

    Full Text Available We study the effect of shear flow on the time damping of linear nonadiabatic magnetoacoustic waves in a solar prominence. We consider a homogeneous, isothermal, and unbounded medium permeated by a uniform magnetic field. The adiabaticity is removed by including the optically thin radiative losses, thermal conduction, and heating term in energy equation. We present a local theory of MHD waves to obtain a dispersion relation. The dispersion relation is solved numerically to study the time damping of these waves. It is found that flow influences the damping time and damping per period of both the slow and fast waves significantly. Damping time and damping per period of slow waves are very much higher than the damping time and damping per period of fast waves.

  11. A linear MHD instability analysis of solar mass ejections with gravitation

    Science.gov (United States)

    Song, M. T.; Wu, S. T.; Dryer, M.

    1987-01-01

    The linear MHD instability of a cylindrical plasma is used to investigate the origin of solar mass ejections, and the dispersion relation is solved numerically. The initial plasma-flow velocity is found to have a significant effect on the instability criteria and growth rate, and the instability growth-rate is shown to be larger in cases where plasma flow exists, relative to the static case. Results suggest that the plasma column may break into small pieces. Assuming a thin-tube approximation, gravity is found to have little effect on the instability of quasi-horizontal ejection, but to have considerable effect on the vertical ejection. In considering the gravitational force, an exact analytical solution is found for the vertical case, while asymptotic solutions are given for the horizontal and oblique cases.

  12. New Frontiers in Schistosoma Genomics and Transcriptomics

    Science.gov (United States)

    Nahum, Laila A.; Mourão, Marina M.; Oliveira, Guilherme

    2012-01-01

    Schistosomes are digenean blood flukes of aves and mammals comprising 23 species. Some species are causative agents of human schistosomiasis, the second major neglected disease affecting over 230 million people worldwide. Modern technologies including the sequencing and characterization of nucleic acids and proteins have allowed large-scale analyses of parasites and hosts, opening new frontiers in biological research with potential biomedical and biotechnological applications. Nuclear genomes of the three most socioeconomically important species (S. haematobium, S. japonicum, and S. mansoni) have been sequenced and are under intense investigation. Mitochondrial genomes of six Schistosoma species have also been completely sequenced and analysed from an evolutionary perspective. Furthermore, DNA barcoding of mitochondrial sequences is used for biodiversity assessment of schistosomes. Despite the efforts in the characterization of Schistosoma genomes and transcriptomes, many questions regarding the biology and evolution of this important taxon remain unanswered. This paper aims to discuss some advances in the schistosome research with emphasis on genomics and transcriptomics. It also aims to discuss the main challenges of the current research and to point out some future directions in schistosome studies. PMID:23227308

  13. Considerations on Energy Frontier Colliders after LHC

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, Vladimir [Fermilab

    2016-11-15

    Since 1960’s, particle colliders have been in the forefront of particle physics, 29 total have been built and operated, 7 are in operation now. At present the near term US, European and international strategies of the particle physics community are centered on full exploitation of the physics potential of the Large Hadron Collider (LHC) through its high-luminosity upgrade (HL-LHC). The future of the world-wide HEP community critically depends on the feasibility of possible post-LHC colliders. The concept of the feasibility is complex and includes at least three factors: feasibility of energy, feasibility of luminosity and feasibility of cost. Here we overview all current options for post-LHC colliders from such perspective (ILC, CLIC, Muon Collider, plasma colliders, CEPC, FCC, HE-LHC) and discuss major challenges and accelerator R&D required to demonstrate feasibility of an energy frontier accelerator facility following the LHC. We conclude by taking a look into ultimate energy reach accelerators based on plasmas and crystals, and discussion on the perspectives for the far future of the accelerator-based particle physics. This paper largely follows previous study [1] and the presenta ion given at the ICHEP’2016 conference in Chicago [2].

  14. Frontiers of higher order fuzzy sets

    CERN Document Server

    Tahayori, Hooman

    2015-01-01

    Frontiers of Higher Order Fuzzy Sets, strives to improve the theoretical aspects of general and Interval Type-2 fuzzy sets and provides a unified representation theorem for higher order fuzzy sets. Moreover, the book elaborates on the concept of gradual elements and their integration with the higher order fuzzy sets. This book also introduces new frameworks for information granulation based on general T2FSs, IT2FSs, Gradual elements, Shadowed sets and rough sets. In particular, the properties and characteristics of the new proposed frameworks are studied. Such new frameworks are shown to be more capable to be exploited in real applications. Higher order fuzzy sets that are the result of the integration of general T2FSs, IT2FSs, gradual elements, shadowed sets and rough sets will be shown to be suitable to be applied in the fields of bioinformatics, business, management, ambient intelligence, medicine, cloud computing and smart grids. Presents new variations of fuzzy set frameworks and new areas of applicabili...

  15. EFISIENSI BANK PEMBANGUNAN DAERAH: PENDEKATAN STOCHASTIC FRONTIER

    Directory of Open Access Journals (Sweden)

    Ahmad Husein Fadhlullah

    2016-01-01

    Full Text Available The objective of this research is to analyze the efficiency rate at Islamic regional banks (BPD in Indonesia, with case of 15 Islamic regional banks from 2008 – 2012. The method that used in this research is stochastic frontier analysis approach (SFA, which uses the input variable (such as human resources cost, administration cost, and other expenses and the output variable is SFA (operational income. The average efficiency rate from 15 Islamic regional banks from 2008 – 2012 with SFA method is 53.21 percent and all of the Islamic regional banks doesn’t achieve the 100 percent efficiency. The most efficient banks is Islamic regional bank of Kalimantan Barat which the efficiency rate achieve 90.42 percent and the most inefficiency banks is Islamic regional bank of Sumatera Barat. The average efficiency rate from 2008-2012 is always increase each year. In 2008 the average efficiency rate only 33.57 percent and in the last of 2012 achieve 71.81 percent.DOI: 10.15408/sjie.v4i1.2291

  16. Coalescence of magnetic islands in the low-resistivity, Hall-MHD regime.

    Science.gov (United States)

    Knoll, D A; Chacón, L

    2006-04-07

    The coalescence of magnetic islands in the low-resistivity eta, Hall-MHD regime is studied. The interaction between the ion inertial length d(i) and the dynamically evolving current sheet scale length deltaJ is established. Initially, d(i) MHD model.

  17. Note: Tangential x-ray diagnosis for investigating fast MHD events in EAST tokamak.

    Science.gov (United States)

    Li, Erzhong; Hu, Liqun; Chen, Kaiyun; Zhang, Jizong; Chen, Yiebin; Zhou, Ruijie; Gan, Kaifu; Liu, Yong

    2010-10-01

    A tangential x-ray diagnosis has been installed in the experimental advanced superconducting tokamakvacuum vessel for the study of fast magnetohydrodynamics (MHD) events. This system is based on absolute x-ray ultraviolet detectors with a collimator which is processed by laser machine. The first experimental results have proved its ability to measure the small-scale and transient MHD perturbations.

  18. The optimization air separation plants for combined cycle MHD-power plant applications

    Science.gov (United States)

    Juhasz, A. J.; Springmann, H.; Greenberg, R.

    1980-01-01

    Some of the design approaches being employed during a current supported study directed at developing an improved air separation process for the production of oxygen enriched air for magnetohydrodynamics (MHD) combustion are outlined. The ultimate objective is to arrive at conceptual designs of air separation plants, optimized for minimum specific power consumption and capital investment costs, for integration with MHD combined cycle power plants.

  19. Long period slow MHD waves in the solar wind source region

    OpenAIRE

    Dwivedi, B. N.; Srivastava, A. K.

    2006-01-01

    We consider compressive viscosity and thermal conductivity to study the propagation and dissipation of long period slow longitudinal MHD waves in polar coronal holes. We discuss their likely role in the line profile narrowing, and in the energy budget for coronal holes and the solar wind. We compare the contribution of longitudinal MHD waves with high frequency Alfven waves.

  20. Design of heat-recovery and seed-recovery units in MHD power generation

    Energy Technology Data Exchange (ETDEWEB)

    Bergman, P.D.; Joubert, J.I.; Demski, R.J.; Bienstock, D.

    1974-01-01

    Crucial and limiting engineering and materials problems associated with the design of an MHD steam bottoming plant are discussed. Existing experimental and theoretical results on corrosion, fouling and deposits, potassium seed recovery and regeneration, are reviewed. The state of knowledge regarding the design of heat recovery and seed recovery units for coal-fired MHD plants is inadequate at the present time.

  1. Chemical reaction in MHD flow past a vertical plate with mass ...

    African Journals Online (AJOL)

    Chemical reaction plays an important role in MHD flow. It has industrial applications, such as design of chemical processing equipments, food processing and cooling towers etc. In the present paper, chemical reaction effect on a viscous, incompressible and electrically conducting fluid with unsteady MHD flow past an ...

  2. Free boundary skin current MHD (magnetohydrodynamic) equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Reusch, M.F.

    1988-02-01

    Function theoretic methods in the complex plane are used to develop simple parametric hodograph formulae which generate sharp boundary equilibria of arbitrary shape. The related method of Gorenflo and Merkel is discussed. A numerical technique for the construction of solutions, based on one of the methods is presented. A study is made of the bifurcations of an equilibrium of general form. 28 refs., 9 figs.

  3. Current frontiers and future directions of telecoupling research

    Science.gov (United States)

    Liu, J.

    2016-12-01

    The world has been increasingly interconnected over long distances though processes such as international trade, migration, telecommunication, and disease spread. However, previous studies often focused on socioeconomic or environmental issues of distant processes. While these studies have generated useful information for individual disciplines, integrating socioeconomic and environmental information is essential for holistic understanding of complex global challenges and unbiased decision making to address the challenges. To advance integrated research, the framework of telecoupling (socioeconomic and environmental interactions over distances) has been developed to explicitly address both socioeconomic and environmental issues simultaneously. Although the framework is relatively new, it has already been applied to tackle a variety of globally important issues, such as food security, water resources, energy sustainability, land use, international trade (e.g., food, forest products, energy, wildlife, industrial products), species invasion, investment, ecosystem services, conservation, information dissemination, and tourism. These applications have identified many important research gaps (e.g. spillover systems) and hidden linkages (e.g. feedbacks) among distant areas of the world with profound implications for sustainable development, ecosystem health, and human well-being. While working with telecoupling presents more challenges than focusing only on disciplinary issues, support from funding agencies has helped accelerate research on telecoupling and more efforts are being aimed at framework quantification and operationalization. The presenter will provide an overview of the current frontiers, discuss future research directions, and highlight emerging opportunities and challenges in telecoupling research and governance.

  4. Technical Efficiency of Thai Manufacturing SMEs: A Stochastic Frontier Analysis

    Directory of Open Access Journals (Sweden)

    Teerawat Charoenrat

    2013-03-01

    Full Text Available AbstractA major motivation of this study is to examine the factors that are the most important in contributing to the relatively poor efficiency performance of Thai manufacturing small and medium sized enterprises (SMEs. The results obtained will be significant in devising effective policies aimed at tackling this poor performance.This paper uses data on manufacturing SMEs in the North-eastern region of Thailand in 2007 as a case study, by applying a stochastic frontier analysis (SFA and a technical inefficiency effects model. The empirical results obtained indicate that the mean technical efficiency of all categories of manufacturing SMEs in theNorth-eastern region is 43%, implying that manufacturing SMEs have high levels of technical inefficiency in their production processes.Manufacturing SMEs in the North-eastern region are particularly labour-intensive. The empirical results of the technical inefficiency effects model suggest that skilled labour, the municipal area and ownership characteristics are important firm-specific factors affecting technical efficiency. The paper argues that the government should play a more substantial role in developing manufacturing SMEs in the North-eastern provinces through: providing training programs for employees and employers; encouraging a greater usage of capital and technology in the production process of SMEs; enhancing the efficiency of state-ownedenterprises; encouraging a wide range of ownership forms; and improving information and communications infrastructure.

  5. Analytical calculation of boozer magnetic coordinates for axisymmetric MHD equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Alladio, F.; Micozzi, P. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dip. Energia

    1995-10-01

    A new analytical technique for extracting the Boozer magnetic coordinates in axisymmetric MHD equilibria is described. The method is based upon the correspondence between the expansion of the flux function in toroidal multipolar moments and the expansion in toroidal axisymmetric harmonics of the magnetic scalar potential {chi}{sub 0}, which appears in the covariant representation B={nabla}{sub {chi}0}+{beta}{nabla}{sub {psi}}-T of the magnetic field. An example of calculation of Boozer magnetic coordinates is given for an experimental highly shaped high {beta} equilibrium of DIIID.

  6. Comparative analysis of CCMHD power plants. [Closed Cycle MHD

    Science.gov (United States)

    Alyea, F. N.; Marston, C. H.; Mantri, V. B.; Geisendorfer, B. G.; Doss, H.

    1981-01-01

    A study of Closed Cycle MHD (CCMHD) power generation systems has been conducted which emphasizes both advances in component conceptual design and overall system performance. New design data are presented for the high temperature, regenerative argon heaters (HTRH) and the heat recovery/seed recovery (HRSR) subsystem. Contamination of the argon by flue gas adsorbed in the HTRH is examined and a model for estimation of contamination effects in operating systems is developed. System performance and cost data have been developed for the standard CCMHD/steam cycle as powered by both direct fired cyclone combustors and selected coal gasifiers. In addition, a new CCMHD thermodynamic cycle has been identified.

  7. Convective-diffusive transport in laminar MHD flows

    Energy Technology Data Exchange (ETDEWEB)

    Buehler, L.

    1993-09-01

    The two questions of main interest for the design of a fusion blanket are whether the heat transfer to the coolant is high enough that the temperature of the plasma facing wall does not exceed a critical value and whether the corrosion rate is below a certain limit. Both processes are governed by convective - diffusive transport mechanisms. A numerical code for the 3D-solution of these equations in the laminar flow regime is discussed. It is assumed that tthe flow is fully developed when entering the heated section of a blanket element. The interaction of the strong magnetic field with the electrically conducting fluid is taken into account by an asymptotic analysis valid for fully developed MHD flows in ducts with arbitrary shape of cross section. Heat transfer conditions are discussed for circular pipes and square ducts. The influence of the main parameters on wall temperature is analyzed in detail and summarized by an empirical correlation. As an example for an extended use of the heat transfer code the full numerical solution of fully developed MHD flows in circular and rectangular ducts is presented. (orig.) [Deutsch] Bei der Auslegung eines Fusionsblankets sind die wichtigen Fragen zu klaeren, ob die Waermeuebertragung an das Kuehlmedium ausreicht, damit die Temperatur der plasmanahen Wand einen kritischen Wert nicht uebersteigt, und ob die Korrosionsraten unterhalb eines gewissen Grenzwertes bleiben. Beide Prozesse werden durch Gleichungen fuer konvektiv - diffusive Transportvorgaenge beschrieben. Es wird ein numerisches Rechenverfahren zur Bestimmung von dreidimensionalen Loesungen dieser Gleichungen im Bereich laminarer Stroemungen vorgestellt. Dabei wird vorausgesetzt, dass die Stroemung beim Eintritt in den beheizten Teil des Blankets bereits voll ausgebildet ist. Die Wechselwirkung des starken Magnetfeldes mit dem elektrisch leitenden Fluid wird durch eine asymptotische Rechnung beruecksichtigt, die fuer voll ausgebildete MHD Stroemungen in Kanaelen mit

  8. Generalized phase mixing: Turbulence-like behaviour from unidirectionally propagating MHD waves.

    Science.gov (United States)

    Magyar, Norbert; Doorsselaere, Tom Van; Goossens, Marcel

    2017-11-01

    We present the results of three-dimensional (3D) ideal magnetohydrodynamics (MHD) simulations on the dynamics of a perpendicularly inhomogeneous plasma disturbed by propagating Alfvénic waves. Simpler versions of this scenario have been extensively studied as the phenomenon of phase mixing. We show that, by generalizing the textbook version of phase mixing, interesting phenomena are obtained, such as turbulence-like behavior and complex current-sheet structure, a novelty in longitudinally homogeneous plasma excited by unidirectionally propagating waves. This study is in the setting of a coronal hole. However, it constitutes an important finding for turbulence-related phenomena in astrophysics in general, relaxing the conditions that have to be fulfilled in order to generate turbulent behavior.

  9. Multi-scale MHD analysis of LHD plasma with background field changing

    Science.gov (United States)

    Ichiguchi, K.; Sakakibara, S.; Ohdachi, S.; Carreras, B. A.

    2015-04-01

    The mechanism of the partial collapse observed in the experiment with the background magnetic field changing in the Large Helical Device (LHD) is numerically investigated with a nonlinear magnetohydrodynamics (MHD) simulation. Since the different timescales of the perturbations and the background field changing have to be treated simultaneously for the analysis of this plasma, a multi-scale simulation scheme is developed. The effect of the perturbation dynamics on the equilibrium pressure and rotational transform is taken into account in this scheme. The result indicates that the collapse is caused by the destabilization of an infernal-like mode due to the magnetic hill enhanced by the change of the background field. The mechanism of the reduction of the central beta observed after the partial collapse in the experiment is also analysed in relation to the effect of the background field changing.

  10. Observation of turbulent intermittency scaling with magnetic helicity in an MHD plasma wind tunnel.

    Science.gov (United States)

    Schaffner, D A; Wan, A; Brown, M R

    2014-04-25

    The intermittency in turbulent magnetic field fluctuations has been observed to scale with the amount of magnetic helicity injected into a laboratory plasma. An unstable spheromak injected into the MHD wind tunnel of the Swarthmore Spheromak Experiment displays turbulent magnetic and plasma fluctuations as it relaxes into a Taylor state. The level of intermittency of this turbulence is determined by finding the flatness of the probability distribution function of increments for magnetic pickup coil fluctuations B˙(t). The intermittency increases with the injected helicity, but spectral indices are unaffected by this variation. While evidence is provided which supports the hypothesis that current sheets and reconnection sites are related to the generation of this intermittent signal, the true nature of the observed intermittency remains unknown.

  11. MHD Natural Convection with Convective Surface Boundary Condition over a Flat Plate

    Directory of Open Access Journals (Sweden)

    Mohammad M. Rashidi

    2014-01-01

    Full Text Available We apply the one parameter continuous group method to investigate similarity solutions of magnetohydrodynamic (MHD heat and mass transfer flow of a steady viscous incompressible fluid over a flat plate. By using the one parameter group method, similarity transformations and corresponding similarity representations are presented. A convective boundary condition is applied instead of the usual boundary conditions of constant surface temperature or constant heat flux. In addition it is assumed that viscosity, thermal conductivity, and concentration diffusivity vary linearly. Our study indicates that a similarity solution is possible if the convective heat transfer related to the hot fluid on the lower surface of the plate is directly proportional to (x--1/2 where x- is the distance from the leading edge of the solid surface. Numerical solutions of the ordinary differential equations are obtained by the Keller Box method for different values of the controlling parameters associated with the problem.

  12. Two-dimensional vacuum ultraviolet images in different MHD events on the EAST tokamak

    Science.gov (United States)

    Zhijun, WANG; Xiang, GAO; Tingfeng, MING; Yumin, WANG; Fan, ZHOU; Feifei, LONG; Qing, ZHUANG; EAST Team

    2018-02-01

    A high-speed vacuum ultraviolet (VUV) imaging telescope system has been developed to measure the edge plasma emission (including the pedestal region) in the Experimental Advanced Superconducting Tokamak (EAST). The key optics of the high-speed VUV imaging system consists of three parts: an inverse Schwarzschild-type telescope, a micro-channel plate (MCP) and a visible imaging high-speed camera. The VUV imaging system has been operated routinely in the 2016 EAST experiment campaign. The dynamics of the two-dimensional (2D) images of magnetohydrodynamic (MHD) instabilities, such as edge localized modes (ELMs), tearing-like modes and disruptions, have been observed using this system. The related VUV images are presented in this paper, and it indicates the VUV imaging system is a potential tool which can be applied successfully in various plasma conditions.

  13. Fast and Slow Solar Wind: Energy Transfer Rate in Compressible MHD Turbulence

    Science.gov (United States)

    Hadid, L.; Sahraoui, F.; Galtier, S.; Banerjee, S.

    2016-12-01

    The role of compressible fluctuations in the energy cascade in the fast and slow solar wind is investigated. A focus is put on comparing the energy cascade rates estimated using the exact laws derived for incompressible MHD turbulence [Politano and Pouquet, 1998] (PP98) and for compressible isothermal turbulence recently derived by Galtier and Banerjee, 2013 (BG13). New features are evidenced using the BG13 model in comparison with the PP98 model: i) broader inertial range (more than two decades of scales); ii) higher energy cascade rate (up to 4 times); iii) less anisotropic cascade rates (along and perpendicular to the local mean field). Furthermore, a term-by-term analysis of the compressible model emphasized the relative importance of the new flux term in the BG13 model, and provided new insight into the role played by the compressible fluctuations in the solar wind.

  14. Fast and Slow solar wind: Energy transferrate in compressible MHD trubulence.

    Science.gov (United States)

    Hadid, Lina; Sahraoui, Fouad; Galtier, Sebastien; Banerjee, Supratik

    2017-04-01

    The role of compressible fluctuations in the energy cascade in the fast and slow solar wind is investigated. A focus is put on comparing the energy cascade rates estimated using the exact laws derived for incompressible MHD turbulence [Politano and Pouquet, 1998] (PP98) and for compressible isothermal turbulence recently derived by Galtier and Banerjee, PRE, 2013 (BG13). New features are evidenced using the BG13 model in comparison with the PP98 model: i) broader inertial range (more than two decades of scales); ii) higher energy cascade rate (up to 4 times); iii) less anisotropic cascade rates (along and perpendicular to the local mean field). Furthermore, a term-by-term analysis of the compressible model emphasized the relative importance of the new flux term in the BG13 model, and provided new insight into the role played by the compressible fluctuations in the solar wind.

  15. Simulated annealing for three-dimensional low-beta reduced MHD equilibria in cylindrical geometry

    CERN Document Server

    Furukawa, M

    2016-01-01

    Simulated annealing (SA) is applied for three-dimensional (3D) equilibrium calculation of ideal, low-beta reduced MHD in cylindrical geometry. The SA is based on the theory of Hamiltonian mechanics. The dynamical equation of the original system, low-beta reduced MHD in this study, is modified so that the energy changes monotonically while preserving the Casimir invariants in the artificial dynamics. An equilibrium of the system is given by an extremum of the energy, therefore SA can be used as a method for calculating ideal MHD equilibrium. Previous studies demonstrated that the SA succeeds to lead to various MHD equilibria in two dimensional rectangular domain. In this paper, the theory is applied to 3D equilibrium of ideal, low-beta reduced MHD. An example of equilibrium with magnetic islands, obtained as a lower energy state, is shown. Several versions of the artificial dynamics are developed that can effect smoothing.

  16. Coal-gasification/MHD/steam-turbine combined-cycle (GMS) power generation

    Energy Technology Data Exchange (ETDEWEB)

    Lytle, J.M.; Marchant, D.D.

    1980-11-01

    The coal-gasification/MHD/steam-turbine combined cycle (GMS) refers to magnetohydrodynamic (MHD) systems in which coal gasification is used to supply a clean fuel (free of mineral matter and sulfur) for combustion in an MHD electrical power plant. Advantages of a clean-fuel system include the elimination of mineral matter or slag from all components other than the coal gasifier and gas cleanup system; reduced wear and corrosion on components; and increased seed recovery resulting from reduced exposure of seed to mineral matter or slag. Efficiencies in some specific GMS power plants are shown to be higher than for a comparably sized coal-burning MHD power plant. The use of energy from the MHD exhaust gas to gasify coal (rather than the typical approach of burning part of the coal) results in these higher efficiencies.

  17. Technical support for open-cycle MHD program. Progress report, April-June 1978

    Energy Technology Data Exchange (ETDEWEB)

    Bomkamp, D H [ed.

    1979-07-01

    The support program for open-cycle MHD at Argonne National Laboratory is developing the analytical tools needed to investigate the performance of the major components in the combined cycle MHD/steam power system. The analytical effort is centered on the primary components of the system that are unique to MHD and also on the integration of these analytical representations into a model of the entire power producing system. The project activities currently include modeling of the combustor, MHD channel, slag separator and the high temperature air heater. In addition, these models are combined into a complete system model which is presently capable of carrying out optimizations of the entire system on either thermodynamic efficiency or cost of electrical power. Also, in support of other aspects of the open-cycle program, test plans are developed and facility and program reviews are provided upon request to support the needs and requirements of the DOE/MHD Division.

  18. The role of MHD instabilities in the improved H-mode scenario

    Energy Technology Data Exchange (ETDEWEB)

    Flaws, Asher

    2009-02-16

    Recently a regime of tokamak operation has been discovered, dubbed the improved H-mode scenario, which simultaneously achieves increased energy confinement and stability with respect to standard H-mode discharges. It has been suggested that magnetohydrodynamic (MHD) instabilities play some role in establishing this regime. In this thesis MHD instabilities were identified, characterised, and catalogued into a database of improved H-mode discharges in order to statistically examine their behaviour. The onset conditions of MHD instabilities were compared to existing models based on previous H-mode studies. Slight differences were found, most notably a reduced {beta}{sub N} onset threshold for the frequently interrupted regime for neoclassical tearing modes (NTM). This reduced threshold is due to the relatively low magnetic shear of the improved H-mode regime. This study also provided a first-time estimate for the seed island size of spontaneous onset NTMs, a phenomenon characteristic of the improved H-mode scenario. Energy confinement investigations found that, although the NTM impact on confinement follows the same model applicable to other operating regimes, the improved H-mode regime acts to mitigate the impact of NTMs by limiting the saturated island sizes for NTMs with toroidal mode number n {>=} 2. Surprisingly, although a significant loss in energy confinement is observed during the sawtooth envelope, it has been found that discharges containing fishbones and low frequency sawteeth achieve higher energy confinement than those without. This suggests that fishbone and sawtooth reconnection may indeed play a role in establishing the high confinement regime. It was found that the time evolution of the central magnetic shear consistently locks in the presence of sawtooth and fishbone reconnection. Presumably this is due to the periodic redistribution of the central plasma current, an effect which is believed to help establish and maintain the characteristic current

  19. The Frontier Fields lens modelling comparison project

    Science.gov (United States)

    Meneghetti, M.; Natarajan, P.; Coe, D.; Contini, E.; De Lucia, G.; Giocoli, C.; Acebron, A.; Borgani, S.; Bradac, M.; Diego, J. M.; Hoag, A.; Ishigaki, M.; Johnson, T. L.; Jullo, E.; Kawamata, R.; Lam, D.; Limousin, M.; Liesenborgs, J.; Oguri, M.; Sebesta, K.; Sharon, K.; Williams, L. L. R.; Zitrin, A.

    2017-12-01

    Gravitational lensing by clusters of galaxies offers a powerful probe of their structure and mass distribution. Several research groups have developed techniques independently to achieve this goal. While these methods have all provided remarkably high-precision mass maps, particularly with exquisite imaging data from the Hubble Space Telescope (HST), the reconstructions themselves have never been directly compared. In this paper, we present for the first time a detailed comparison of methodologies for fidelity, accuracy and precision. For this collaborative exercise, the lens modelling community was provided simulated cluster images that mimic the depth and resolution of the ongoing HST Frontier Fields. The results of the submitted reconstructions with the un-blinded true mass profile of these two clusters are presented here. Parametric, free-form and hybrid techniques have been deployed by the participating groups and we detail the strengths and trade-offs in accuracy and systematics that arise for each methodology. We note in conclusion that several properties of the lensing clusters are recovered equally well by most of the lensing techniques compared in this study. For example, the reconstruction of azimuthally averaged density and mass profiles by both parametric and free-form methods matches the input models at the level of ∼10 per cent. Parametric techniques are generally better at recovering the 2D maps of the convergence and of the magnification. For the best-performing algorithms, the accuracy in the magnification estimate is ∼10 per cent at μtrue = 3 and it degrades to ∼30 per cent at μtrue ∼ 10.

  20. Report on results of contract research. 'Research on MHD generation system'; MHD hatsuden system no kenkyu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1981-03-01

    'Research on MHD generation system' was implemented by its expert committee in the electric joint study group, with the results of fiscal 1980 reported. This year, a detailed conceptual design was carried out on a coal fired MHD generation system, with points for the technological development concretely examined. In addition, investigation was conducted on the progress of MHD generation technology, development situation of other generation systems, state of energy resources, etc., in various foreign countries. In the conceptual design of the coal fired MHD generation plant, the system structure of a 2,000 MWt class commercial MHD generation plant was explained, as were the conceptual design of the structural elements and proposals for a 500 MWt class demonstration plant and an 100 MWt class experimental plant, for example. In the overseas trend of R and D on MHD generation, investigations were made concerning the U.S., Soviet Union, and China, with details compiled for such items as generation plants, combustors, generation channels, heat resisting materials, superconducting magnets, heat exchangers, seed slags, inverters, boilers and environments, and commercial plants. (NEDO)

  1. The New Frontiers Venus In Situ Atmospheric and Geochemical Explorer (VISAGE) Mission Proposal

    Science.gov (United States)

    Esposito, L. W.; Atkinson, D. H.; Baines, K. H.

    2017-09-01

    The New Frontiers Venus In Situ Atmospheric and Geochemical Explorer (VISAGE) Mission Proposal submitted to 2017 New Frontiers 4 program by University of Colorado, managed by Caltech/Jet Propulsion Laboratory.

  2. CAFE: A New Relativistic MHD Code

    Science.gov (United States)

    Lora-Clavijo, F. D.; Cruz-Osorio, A.; Guzmán, F. S.

    2015-06-01

    We introduce CAFE, a new independent code designed to solve the equations of relativistic ideal magnetohydrodynamics (RMHD) in three dimensions. We present the standard tests for an RMHD code and for the relativistic hydrodynamics regime because we have not reported them before. The tests include the one-dimensional Riemann problems related to blast waves, head-on collisions of streams, and states with transverse velocities, with and without magnetic field, which is aligned or transverse, constant or discontinuous across the initial discontinuity. Among the two-dimensional (2D) and 3D tests without magnetic field, we include the 2D Riemann problem, a one-dimensional shock tube along a diagonal, the high-speed Emery wind tunnel, the Kelvin-Helmholtz (KH) instability, a set of jets, and a 3D spherical blast wave, whereas in the presence of a magnetic field we show the magnetic rotor, the cylindrical explosion, a case of Kelvin-Helmholtz instability, and a 3D magnetic field advection loop. The code uses high-resolution shock-capturing methods, and we present the error analysis for a combination that uses the Harten, Lax, van Leer, and Einfeldt (HLLE) flux formula combined with a linear, piecewise parabolic method and fifth-order weighted essentially nonoscillatory reconstructors. We use the flux-constrained transport and the divergence cleaning methods to control the divergence-free magnetic field constraint.

  3. CAFE: A NEW RELATIVISTIC MHD CODE

    Energy Technology Data Exchange (ETDEWEB)

    Lora-Clavijo, F. D.; Cruz-Osorio, A. [Instituto de Astronomía, Universidad Nacional Autónoma de México, AP 70-264, Distrito Federal 04510, México (Mexico); Guzmán, F. S., E-mail: fdlora@astro.unam.mx, E-mail: aosorio@astro.unam.mx, E-mail: guzman@ifm.umich.mx [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo. Edificio C-3, Cd. Universitaria, 58040 Morelia, Michoacán, México (Mexico)

    2015-06-22

    We introduce CAFE, a new independent code designed to solve the equations of relativistic ideal magnetohydrodynamics (RMHD) in three dimensions. We present the standard tests for an RMHD code and for the relativistic hydrodynamics regime because we have not reported them before. The tests include the one-dimensional Riemann problems related to blast waves, head-on collisions of streams, and states with transverse velocities, with and without magnetic field, which is aligned or transverse, constant or discontinuous across the initial discontinuity. Among the two-dimensional (2D) and 3D tests without magnetic field, we include the 2D Riemann problem, a one-dimensional shock tube along a diagonal, the high-speed Emery wind tunnel, the Kelvin–Helmholtz (KH) instability, a set of jets, and a 3D spherical blast wave, whereas in the presence of a magnetic field we show the magnetic rotor, the cylindrical explosion, a case of Kelvin–Helmholtz instability, and a 3D magnetic field advection loop. The code uses high-resolution shock-capturing methods, and we present the error analysis for a combination that uses the Harten, Lax, van Leer, and Einfeldt (HLLE) flux formula combined with a linear, piecewise parabolic method and fifth-order weighted essentially nonoscillatory reconstructors. We use the flux-constrained transport and the divergence cleaning methods to control the divergence-free magnetic field constraint.

  4. CAFE: A New Relativistic MHD Code

    CERN Document Server

    Lora-Clavijo, F D; Guzman, F S

    2014-01-01

    We present CAFE, a new independent code designed to solve the equations of Relativistic ideal Magnetohydrodynamics (RMHD) in 3D. We present the standard tests for a RMHD code and for the Relativistic Hydrodynamics (RMD) regime since we have not reported them before. The tests include the 1D Riemann problems related to blast waves, head-on collision of streams and states with transverse velocities, with and without magnetic field, which is aligned or transverse, constant or discontinuous across the initial discontinuity. Among the 2D tests, without magnetic field we include the 2D Riemann problem, the high speed Emery wind tunnel, the Kelvin-Helmholtz instability test and a set of jets, whereas in the presence of a magnetic field we show the magnetic rotor, the cylindrical explosion and the Kelvin-Helmholtz instability. The code uses High Resolution Shock Capturing methods and as a standard set up we present the error analysis with a simple combination that uses the HLLE flux formula combined with linear, PPM ...

  5. Landscape of Future Accelerators at the Energy and Intensity Frontier

    Energy Technology Data Exchange (ETDEWEB)

    Syphers, M. J. [Northern Illinois U.; Chattopadhyay, S. [Northern Illinois U.

    2016-11-21

    An overview is provided of the currently envisaged landscape of charged particle accelerators at the energy and intensity frontiers to explore particle physics beyond the standard model via 1-100 TeV-scale lepton and hadron colliders and multi-Megawatt proton accelerators for short- and long- baseline neutrino experiments. The particle beam physics, associated technological challenges and progress to date for these accelerator facilities (LHC, HL-LHC, future 100 TeV p-p colliders, Tev-scale linear and circular electron-positron colliders, high intensity proton accelerator complex PIP-II for DUNE and future upgrade to PIP-III) are outlined. Potential and prospects for advanced “nonlinear dynamic techniques” at the multi-MW level intensity frontier and advanced “plasma- wakefield-based techniques” at the TeV-scale energy frontier and are also described.

  6. Sunspot Modeling: From Simplified Models to Radiative MHD Simulations

    Directory of Open Access Journals (Sweden)

    Rolf Schlichenmaier

    2011-09-01

    Full Text Available We review our current understanding of sunspots from the scales of their fine structure to their large scale (global structure including the processes of their formation and decay. Recently, sunspot models have undergone a dramatic change. In the past, several aspects of sunspot structure have been addressed by static MHD models with parametrized energy transport. Models of sunspot fine structure have been relying heavily on strong assumptions about flow and field geometry (e.g., flux-tubes, "gaps", convective rolls, which were motivated in part by the observed filamentary structure of penumbrae or the necessity of explaining the substantial energy transport required to maintain the penumbral brightness. However, none of these models could self-consistently explain all aspects of penumbral structure (energy transport, filamentation, Evershed flow. In recent years, 3D radiative MHD simulations have been advanced dramatically to the point at which models of complete sunspots with sufficient resolution to capture sunspot fine structure are feasible. Here overturning convection is the central element responsible for energy transport, filamentation leading to fine-structure and the driving of strong outflows. On the larger scale these models are also in the progress of addressing the subsurface structure of sunspots as well as sunspot formation. With this shift in modeling capabilities and the recent advances in high resolution observations, the future research will be guided by comparing observation and theory.

  7. Kinetic effects of energetic particles on resistive MHD stability.

    Science.gov (United States)

    Takahashi, R; Brennan, D P; Kim, C C

    2009-04-03

    We show that the kinetic effects of energetic particles can play a crucial role in the stability of the m/n=2/1 tearing mode in tokamaks (e.g., JET, JT-60U, and DIII-D), where the fraction of energetic particle beta(frac) is high. Using model equilibria based on DIII-D experimental reconstructions, the nonideal MHD linear stability of cases unstable to the 2/1 mode is investigated including a deltaf particle-in-cell model for the energetic particles coupled to the nonlinear 3D resistive MHD code NIMROD [C. C. Kim et al., Phys. Plasmas 15, 072507 (2008)10.1063/1.2949704]. It is observed that energetic particles have significant damping and stabilizing effects at experimentally relevant beta, beta(frac), and S, and excite a real frequency of the 2/1 mode. Extrapolation of the results is discussed for implications to JET and ITER, where the effects are projected to be significant.

  8. Observation of MHD phenomenon for SST-1 superconducting tokamak

    Science.gov (United States)

    Bhandarkar, Manisha; Dhongde, Jasraj; Pradhan, Subrata

    2017-04-01

    Steady State Superconducting Tokamak (SST-1) is a medium size Tokamak (major radius = 1.1 m, minor radius = 0.2 m) and is operational at the Institute for Plasma Research (IPR), India. In the last few experimental campaigns SST-1 has successfully achieved plasma current in order of 60-70kA and plasma duration in excess of ∼ 500 ms at a central magnetic field of 1.5T. An attempt has made to study the behavior of the magneto-hydrodynamic (MHD) activity during different phases of plasma pulse which leads to major/minor disruptions, its present modes (poloidal/toroidal mode number i.e. m = 2, n = 1) impact on plasma confinement and signature of lock mode and its frequency in the SST-1 plasma using experimental data from Mirnov signals. Observed MHD phenomenon has also been correlated with other diagnostics (i.e. ECE, Density, Soft X-Ray etc.) and heating system (ECRH) for the recent campaigns of SST-1.

  9. Laser production and heating of plasma for MHD application

    Science.gov (United States)

    Jalufka, N. W.

    1988-01-01

    Experiments have been made on the production and heating of plasmas by the absorption of laser radiation. These experiments were performed to ascertain the feasibility of using laser-produced or laser-heated plasmas as the input for a magnetohydrodynamic (MHD) generator. Such a system would have a broad application as a laser-to-electricity energy converter for space power transmission. Experiments with a 100-J-pulsed CO2 laser were conducted to investigate the breakdown of argon gas by a high-intensity laser beam, the parameters (electron density and temperature) of the plasma produced, and the formation and propagation of laser-supported detonation (LSD) waves. Experiments were also carried out using a 1-J-pulsed CO2 laser to heat the plasma produced in a shock tube. The shock-tube hydrogen plasma reached electron densities of approximately 10 to the 17th/cu cm and electron temperatures of approximately 1 eV. Absorption of the CO2 laser beam by the plasma was measured, and up to approximately 100 percent absorption was observed. Measurements with a small MHD generator showed that the energy extraction efficiency could be very large with values up to 56 percent being measured.

  10. Hypersonic MHD Propulsion System Integration for the Mercury Lightcraft

    Science.gov (United States)

    Myrabo, L. N.; Rosa, R. J.

    2004-03-01

    Introduced herein are the design, systems integration, and performance analysis of an exotic magnetohydrodynamic (MHD) slipstream accelerator engine for a single-occupant ``Mercury'' lightcraft. This ultra-energetic, laser-boosted vehicle is designed to ride a `tractor beam' into space, transmitted from a future orbital network of satellite solar power stations. The lightcraft's airbreathing combined-cycle engine employs a rotary pulsed detonation thruster mode for lift-off & landing, and an MHD slipstream accelerator mode at hypersonic speeds. The latter engine transforms the transatmospheric acceleration path into a virtual electromagnetic `mass-driver' channel; the hypersonic momentum exchange process (with the atmosphere) enables engine specific impulses in the range of 6000 to 16,000 seconds, and propellant mass fractions as low as 10%. The single-stage-to-orbit, highly reusable lightcraft can accelerate at 3 Gs into low Earth orbit with its throttle just barely beyond `idle' power, or virtually `disappear' at 30 G's and beyond. The objective of this advanced lightcraft design is to lay the technological foundations for a safe, very low cost (e.g., 1000X below chemical rockets) air and space transportation for human life in the mid-21st Century - a system that will be completely `green' and independent of Earth's limited fossil fuel reserves.

  11. High Field Side MHD Activity During Local Helicity Injection

    Science.gov (United States)

    Pachicano, J. L.; Bongard, M. W.; Fonck, R. J.; Perry, J. M.; Reusch, J. A.; Richner, N. J.

    2017-10-01

    MHD is an essential part of understanding the mechanism for local helicity injection (LHI) current drive. The new high field side (HFS) LHI system on the Pegasus ST permits new tests of recent NIMROD simulations. In that model, LHI current streams in the plasma edge undergo large-scale reconnection events, leading to current drive. This produces bursty n = 1 activity around 30 kHz on low field side (LFS) Mirnov coils, consistent with experiment. The simulations also feature coherent injector streams winding down the center column. Improvements to the core high-resolution poloidal Mirnov array with Cat7A Ethernet cabling and differentially driven signal processing eliminated EMI-driven switching noise, enabling detailed spectral analysis. Preliminary results from the recovered HFS poloidal Mirnov coils suggest n = 1 activity is present at the top of the vessel core, but does not persist down the centerstack. HFS LHI experiments can exhibit an operating regime where the high amplitude MHD is abruptly reduced by more than an order of magnitude on LFS Mirnov coils, leading to higher plasma current and improved particle confinement. This reduction is not observed on the HFS midplane magnetics. Instead, they show broadband turbulence-like magnetic features with near consistent amplitude in a frequency range of 90-200 kHz. Work supported by US DOE Grant DE-FG02-96ER54375.

  12. The Proposition: Imagining Race, Family and Violence on the Nineteenth-Century Australian Frontier

    Directory of Open Access Journals (Sweden)

    Catriona Elder

    2016-06-01

    Full Text Available http://dx.doi.org/10.5007/2175-8026.2016v69n2p165 This article analyses John Hillcoat’s 2005 film The Proposition in relation to a spate of Australian films about violence and the (postcolonial encounter released in the early twenty-first century. Extending on  Felicity Collins and Therese Davis argument that these films can be read in terms of the ways they capture or refract aspects of contemporary race relations in Australia in a post-Mabo, this article analyses how The Proposition reconstructs the trauma of the Australian frontier; how from the perspective of the twenty-first century it worries over the meaning of violence on the Australian frontier. It also explores what has become speakable (and remains unspeakable in the public sphere about the history of the frontier encounter, especially in terms of family and race.  The article argues that The Proposition and other early twenty-first century race relations films can be understood as post-reconciliation films, emerging in a period when Indigenous and non-Indigenous Australians were rethinking ideas of belonging through a prism of post-enmity and forgiveness. Drawing on the theme of violence and intimate relations in the film, this article argues that the challenges to the everyday formulation of Australian history proffered in The Proposition reveal painful and powerful differences amongst Australian citizens’ understanding of who belongs and how they came to belong to the nation. I suggest that by focusing on violence in terms of intimacy, relationships, family and kin, it is possible to see this film presented an opportunity to begin to refigure ideas of belonging.

  13. Greek perceptions of frontier in Magna Graecia: literature and archaeology in dialogue

    Directory of Open Access Journals (Sweden)

    Airton POLLINI

    2013-07-01

    Full Text Available The paper deals with Greek perceptions of frontier in Magna Graecia, from a historical archaeological, contextual standpoint. Considering the complex relationship between literary and archaeological evidence, the paper uses as a case study the frontier in Southern Italy, discussing the subjective frontier perceptions by Greeks and Natives in interaction.

  14. 40 CFR 81.24 - Niagara Frontier Intrastate Air Quality Control Region.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Niagara Frontier Intrastate Air... Air Quality Control Regions § 81.24 Niagara Frontier Intrastate Air Quality Control Region. The Niagara Frontier Intrastate Air Quality Control Region (New York) consists of the territorial area...

  15. Tractable Approximation to Robust Nonlinear Production Frontier Problem

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2012-01-01

    Full Text Available Robust optimization is a rapidly developing methodology for handling optimization problems affected by the uncertain-but-bounded data perturbations. In this paper, we consider the nonlinear production frontier problem where the traditional expected linear cost minimization objective is replaced by one that explicitly addresses cost variability. We propose a robust counterpart for the nonlinear production frontier problem that preserves the computational tractability of the nominal problem. We also provide a guarantee on the probability that the robust solution is feasible when the uncertain coefficients obey independent and identically distributed normal distributions.

  16. Productivity of Nations: A Stochastic Frontier Approach to TFP Decomposition

    Directory of Open Access Journals (Sweden)

    Jorge Oliveira Pires

    2012-01-01

    Full Text Available This paper tackles the problem of aggregate TFP measurement using stochastic frontier analysis. We estimate a world production frontier for a sample of 75 countries over a long period. The “Bauer-Kumbhakar” decomposition of TFP is applied to a smaller sample in order to evaluate the effects of changes in efficiency (technical and allocative, scale effects, and technical change. Estimated technical efficiency scores are compared to productivity indexes offered by nonfrontier studies. We conclude that differences in productivity are responsible for virtually all the differences of growth performance between developed and developing nations and that a large part of this is due to allocative efficiency.

  17. The 2016 Frontiers in Medicinal Chemistry Conference in Bonn.

    Science.gov (United States)

    Müller, Christa E; Thimm, Dominik; Baringhaus, Karl-Heinz

    2017-01-05

    Pushing the frontiers of medicinal chemistry: Christa Müller, Dominik Thimm, and Karl-Heinz Baringhaus look back at the events of the 2016 Frontiers in Medicinal Chemistry (FiMC) Conference held in Bonn, Germany. The report highlights the themes & talks in the annual conference hosted by the Joint Division of Medicinal Chemistry of the German Pharmaceutical Society (DPhG) and German Chemical Society (GDCh). It is also an invitation to the 2017 conference in Bern, Switzerland this February 12-15. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. The Hubble Space Telescope Frontier Fields Program

    Science.gov (United States)

    Koekemoer, Anton M.; Mack, Jennifer; Lotz, Jennifer M.; Borncamp, David; Khandrika, Harish G.; Lucas, Ray A.; Martlin, Catherine; Porterfield, Blair; Sunnquist, Ben; Anderson, Jay; Avila, Roberto J.; Barker, Elizabeth A.; Grogin, Norman A.; Gunning, Heather C.; Hilbert, Bryan; Ogaz, Sara; Robberto, Massimo; Sembach, Kenneth; Flanagan, Kathryn; Mountain, Matt

    2017-08-01

    The Hubble Space Telescope Frontier Fields program is a large Director's Discretionary program of 840 orbits, to obtain ultra-deep observations of six strong lensing clusters of galaxies, together with parallel deep blank fields, making use of the strong lensing amplification by these clusters of distant background galaxies to detect the faintest galaxies currently observable in the high-redshift universe. The entire program has now completed successfully for all 6 clusters, namely Abell 2744, Abell S1063, Abell 370, MACS J0416.1-2403, MACS J0717.5+3745 and MACS J1149.5+2223,. Each of these was observed over two epochs, to a total depth of 140 orbits on the main cluster and an associated parallel field, obtaining images in ACS (F435W, F606W, F814W) and WFC3/IR (F105W, F125W, F140W, F160W) on both the main cluster and the parallel field in all cases. Full sets of high-level science products have been generated for all these clusters by the team at STScI, including cumulative-depth data releases during each epoch, as well as full-depth releases after the completion of each epoch. These products include all the full-depth distortion-corrected drizzled mosaics and associated products for each cluster, which are science-ready to facilitate the construction of lensing models as well as enabling a wide range of other science projects. Many improvements beyond default calibration for ACS and WFC3/IR are implemented in these data products, including corrections for persistence, time-variable sky, and low-level dark current residuals, as well as improvements in astrometric alignment to achieve milliarcsecond-level accuracy. The full set of resulting high-level science products and mosaics are publicly delivered to the community via the Mikulski Archive for Space Telescopes (MAST) to enable the widest scientific use of these data, as well as ensuring a public legacy dataset of the highest possible quality that is of lasting value to the entire community.

  19. Comparison of the Frontier Distributed Database Caching System with NoSQL Databases

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Non-relational "NoSQL" databases such as Cassandra and CouchDB are best known for their ability to scale to large numbers of clients spread over a wide area. The Frontier distributed database caching system, used in production by the Large Hadron Collider CMS and ATLAS detector projects, is based on traditional SQL databases but also has the same high scalability and wide-area distributability for an important subset of applications. This paper compares the architectures, behavior, performance, and maintainability of the two different approaches and identifies the criteria for choosing which approach to prefer over the other.

  20. Comparison of three artificial models of the MHD effect on the electrocardiogram

    Science.gov (United States)

    Oster, Julien; Llinares, Raul; Payne, Stephen; Tse, Zion Tsz Ho; Schmidt, Ehud Jeruham; Clifford, Gari D.

    2013-01-01

    The Electrocardiogram (ECG) is often acquired during Magnetic Resonance Imaging (MRI) for both image acquisition synchronisation with heart activity and patient monitoring to alert for life-threatening events. Accurate ECG analysis is mandatory for cutting-edge applications, such as MRI guided interventions. Nevertheless, the majority of the clinical analysis of ECG acquired inside MRI is made difficult by the superposition of a voltage called the MagnetoHydroDynamic (MHD) effect. MHD is induced by the flow of electrically charged particles in the blood perpendicular to the static magnetic field, which creates a potential of the order of magnitude of the ECG and temporally coincident with the repolatisation period. In this study, a new MHD model is proposed which is an extension of several existing models and incorporates MRI-based blood flow measurements made across the aortic arch. The model is extended to several cardiac cycles to allow the simulation of a realistic ECG acquisition during MRI examination and the quality assessment of MHD suppression techniques. A comparison of two existing models is made with our new model and with an estimate of the MHD voltage observed during a real MRI scan. Results indicate a good agreement between our proposed model and the estimated MHD for most leads, although there are clearly some descrepencies with the observed signal which are likely to be due to remaining deficiencies in the model. However, the results demonstrate that our new model provides a closer approximation to observed MHD effects and a better depiction of the complexity of the MHD effect compared to the previously published models. The source code will be made freely available under and open source license to facilitate collaboration and allow more rapid development of more accurate models of the MHD effect. PMID:24761753

  1. Experimental investigation of MHD heat transfer in a vertical round tube affected by transverse magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Melnikov, I.A., E-mail: corpuskula@gmail.com; Sviridov, E.V.; Sviridov, V.G.; Razuvanov, N.G.

    2016-11-15

    Highlights: • Local and averaged heat transfer coefficient are measured. • Free convection influence on MHD-flow is investigated. • The region with the free convection effect of MHD-heat transfer is found. • Temperature low-frequency fluctuations of abnormally high amplitude are detected. • Analysis of the MHD-heat transfer experimental data is performed. - Abstract: The article is devoted to the results of experimental investigation of heat transfer for a downward mercury flow in a vertical round tube in the presence of a transverse magnetic with non-uniform heat flux along the tube circumference.

  2. Mitigation of magnetohydrodynamic electromagnetic pulse (MHD-EMP) effects from commerical electric power systems

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, P.R. (Oak Ridge National Lab., TN (United States)); Tesche, F.M. (Tesche (F.M.), Dallas, TX (United States)); Vance, E.F. (Vance (E.F.), Fort Worth, TX (United States))

    1992-03-01

    A large nuclear detonation at altitudes of several hundred kilometers above the earth distorts the earth's magnetic field and produces a strong magnetohydrodynamic electromagnetic pulse (MHD-EMP). This can adversely affect electrical power systems. In this report, the effects of this nuclear environment on critical facilities connected to the commercial power system are considered. Methods of mitigating the MHD-EMP impacts are investigated, and recommended protection schemes are presented. Guidelines for testing facilities to determine the effects of MHD-EMP and to validate the mitigation methods also are discussed.

  3. A spectral Galerkin method for the coupled Orr-Sommerfeld and induction equations for free-surface MHD.

    Energy Technology Data Exchange (ETDEWEB)

    Giannakis, D.; Fischer, P. F.; Rosner, R.; Univ. of Chicago

    2009-01-01

    We develop and test spectral Galerkin schemes to solve the coupled Orr-Sommerfeld and induction equations for parallel, incompressible MHD in free-surface and fixed-boundary geometries. The schemes discrete bases consist of Legendre internal shape functions, supplemented with nodal shape functions for the weak imposition of the stress and insulating boundary conditions. The orthogonality properties of the basis polynomials solve the matrix-coefficient growth problem, and eigenvalue-eigenfunction pairs can be computed stably at spectral orders at least as large as p=3000 with p-independent roundoff error. Accuracy is limited instead by roundoff sensitivity due to non-normality of the stability operators at large hydrodynamic and/or magnetic Reynolds numbers (Re,Rm {ge} 4 x 10{sup 4}). In problems with Hartmann velocity and magnetic-field profiles we employ suitable Gauss quadrature rules to evaluate the associated exponentially weighted sesquilinear forms without error. An alternative approach, which involves approximating the forms by means of Legendre-Gauss-Lobatto quadrature at the 2p?1 precision level, is found to yield equal eigenvalues within roundoff error. As a consistency check, we compare modal growth rates to energy growth rates in nonlinear simulations and record relative discrepancy smaller than 10{sup -5} for the least stable mode in free-surface flow at Re = 3 x 10{sup 4}. Moreover, we confirm that the computed normal modes satisfy an energy conservation law for free-surface MHD with error smaller than 10{sup -6}. The critical Reynolds number in free-surface MHD is found to be sensitive to the magnetic Prandtl number Pm, even at the Pm=O(10{sup -5}) regime of liquid metals.

  4. Experimental Research at the Intensity Frontier in High Energy Physics

    Energy Technology Data Exchange (ETDEWEB)

    Marshak, Marvin L. [Univ. of Minnesota, Minneapolis, MN (United States)

    2014-06-30

    This Final Report describes DOE-supported Intensity Frontier research by the University of Minnesota during the interval April 1, 2011 to March 31, 2014. Primary activities included the MINOS, NOvA and LBNE Experiments and Heavy Quark studies at BES III.

  5. Application of stochastic frontier approach model to assess technical ...

    African Journals Online (AJOL)

    Application of stochastic frontier approach model to assess technical efficiency in Kenya's maize production. ... primary school education would enhance maize productivity. Thus, if hybrid seeds, tractor services and agricultural credit ... efficiency would increase. Key words: Socio-economic factors, farm characteristics, maize ...

  6. Frontier models for evaluating environmental efficiency: an overview

    NARCIS (Netherlands)

    Oude Lansink, A.G.J.M.; Wall, A.

    2014-01-01

    Our aim in this paper is to provide a succinct overview of frontier-based models used to evaluate environmental efficiency, with a special emphasis on agricultural activity. We begin by providing a brief, up-to-date review of the main approaches used to measure environmental efficiency, with

  7. India’s Northeast: The Frontier in Ferment

    Science.gov (United States)

    2008-09-01

    letter of 8 August 1901: Where there is an ethnological boundary it will be said that a fur- ther extension is necessary in order to secure a good...natural and geographical boundary. When the boundary is a natural one, an ethnological frontier is declared to be the best. When the boundary is a

  8. A Schoolmarm All My Life: Personal Narratives from Frontier Utah.

    Science.gov (United States)

    Kinkead, Joyce, Ed.

    This book presents edited versions of the personal narratives of 24 Mormon women who taught school in frontier Utah. Drawn primarily from the archives of the Church of Jesus Christ of Latter-Day Saints, the accounts detail the women's lives as Mormons, as pioneers, and as teachers and have been edited to focus on the education of women,…

  9. New insights into the stochastic ray production frontier

    DEFF Research Database (Denmark)

    Henningsen, Arne; Bělín, Matěj; Henningsen, Géraldine

    The stochastic ray production frontier was developed as an alternative to the traditional output distance function to model production processes with multiple inputs and multiple outputs. Its main advantage over the traditional approach is that it can be used when some output quantities of some...

  10. Pesticide use and biodiversity conservation in the Amazonian agricultural frontier.

    Science.gov (United States)

    Schiesari, Luis; Waichman, Andrea; Brock, Theo; Adams, Cristina; Grillitsch, Britta

    2013-06-05

    Agricultural frontiers are dynamic environments characterized by the conversion of native habitats to agriculture. Because they are currently concentrated in diverse tropical habitats, agricultural frontiers are areas where the largest number of species is exposed to hazardous land management practices, including pesticide use. Focusing on the Amazonian frontier, we show that producers have varying access to resources, knowledge, control and reward mechanisms to improve land management practices. With poor education and no technical support, pesticide use by smallholders sharply deviated from agronomical recommendations, tending to overutilization of hazardous compounds. By contrast, with higher levels of technical expertise and resources, and aiming at more restrictive markets, large-scale producers adhered more closely to technical recommendations and even voluntarily replaced more hazardous compounds. However, the ecological footprint increased significantly over time because of increased dosage or because formulations that are less toxic to humans may be more toxic to other biodiversity. Frontier regions appear to be unique in terms of the conflicts between production and conservation, and the necessary pesticide risk management and risk reduction can only be achieved through responsibility-sharing by diverse stakeholders, including governmental and intergovernmental organizations, NGOs, financial institutions, pesticide and agricultural industries, producers, academia and consumers.

  11. Efficiency in the Community College Sector: Stochastic Frontier Analysis

    Science.gov (United States)

    Agasisti, Tommaso; Belfield, Clive

    2017-01-01

    This paper estimates technical efficiency scores across the community college sector in the United States. Using stochastic frontier analysis and data from the Integrated Postsecondary Education Data System for 2003-2010, we estimate efficiency scores for 950 community colleges and perform a series of sensitivity tests to check for robustness. We…

  12. Frontier Man: A "Festschrift" Tribute to Andy Hargreaves

    Science.gov (United States)

    Fullan, Michael

    2011-01-01

    Throughout his career, Andy Hargreaves has continuously pushed the boundaries of knowledge and practice in the field of educational change. He has broken new ground so often that I have come to think of him as a "frontier man." Andy has also been a generous mentor to colleagues and students enhancing the level of scholarship and expertise in his…

  13. A translog stochastic frontier analysis of plot size and cost ...

    African Journals Online (AJOL)

    A stochastic frontier translog cost function model was used to measure the level of cost efficiency and its determinants in small-holder cassava production in South-east Agro-Ecological Zone, Nigeria. A multi-stage random sampling technique was used to select 320 cassava farmers in 2008. The parameters of the stochastic ...

  14. Heroines on Horseback: The Frontier Nursing Service of Appalachia

    Science.gov (United States)

    Sheffield, Caroline C.

    2014-01-01

    The men of the Breckinridge family have a long history of service to the nation, including many politicians, soldiers, and even a vice president of the United States. But it was a woman in the family, Mary, who had, arguably, the most direct and long-lived impact on those she served. As the founder of the Frontier Nursing Service (FNS) of Eastern…

  15. Institutions and bank performance : A stochastic frontier analysis

    NARCIS (Netherlands)

    Lensink, Robert; Meesters, Aljar

    This article investigates the impact of institutions on bank efficiency and technology, using a stochastic frontier analysis of a data set of 7,959 banks across 136 countries over 10 years. The results confirm the importance of well-developed institutions for the efficient operation of commercial

  16. Frontier and Border Regions in Early Modern Europe

    NARCIS (Netherlands)

    Esser, R.M.; Ellis, Steven G.

    2013-01-01

    That regional identities are constructed is now something of a truism in academic research. More recently regions have been conceptualized in the framework of Frontier and Border Studies, thus emphasizing their relationship to their neighbours in another state across a boundary line. In early modern

  17. Nutrition Frontiers E-Newsletter | Division of Cancer Prevention

    Science.gov (United States)

    The Nutritional Science Research Group, Division of Cancer Prevention at NCI issues a quarterly electronic newsletter, Nutrition Frontiers, that highlights emerging evidence linking diet to cancer prevention and showcases recent findings about who will likely benefit most from dietary change. |

  18. Nutrition Frontiers - Spring 2016 | Division of Cancer Prevention

    Science.gov (United States)

    Volume 7, Issue 2 The spring issue of Nutrition Frontiers showcases green tea's effect on human metabolism, fish oil — as a chemopreventive agent in myeloid leukemia and, with pectin, how they affect microRNA expression in the colon. Learn about our spotlight investigator, Dr. Richard Eckert, and his research on skin cancer prevention, upcoming announcements and more. |

  19. Nutrition Frontiers - Winter 2017 | Division of Cancer Prevention

    Science.gov (United States)

    Volume 8, Issue 1 Dear Colleague, The winter issue of Nutrition Frontiers showcases gut permeability and calcium supplementation, potential chemopreventive effects of dietary DHM for lung tumorigenesis, and the role of the MCP-1 chemokine on adiposity and inflammation. Learn about our spotlight investigator, Dr. Gregory Lesinski, and his research on dietary interventions to inhibit carcinogenesis, upcoming announcements and more. |

  20. Nutrition Frontiers - Winter 2018 | Division of Cancer Prevention

    Science.gov (United States)

    Dear Colleague, The winter issue of Nutrition Frontiers showcases the chemopreventive activity of sulforaphane, how a high fat, high cholesterol diet may impact hepatocellular carcinoma, and p53 activation from benzyl isothiocyanate. Meet our spotlight investigator, Dr. John Groopman, and his research on detoxication of air pollutants with a broccoli supplement. Learn about miso, the buttery probiotic, upcoming announcements and more. |

  1. Stochastic Frontier Estimation of Efficient Learning in Video Games

    Science.gov (United States)

    Hamlen, Karla R.

    2012-01-01

    Stochastic Frontier Regression Analysis was used to investigate strategies and skills that are associated with the minimization of time required to achieve proficiency in video games among students in grades four and five. Students self-reported their video game play habits, including strategies and skills used to become good at the video games…

  2. Perinatal mortality at Frontier Hospital, Queenstown - a 6-year audit ...

    African Journals Online (AJOL)

    Objectives. To determine the perinatal mortality rate (PNMR), the neonatal mortality rate (NNMR), the major obstetric and neonatal causes of death, the occurrence of avoidable factors in perinatal deaths, and syphilis serology at the time of delivery at Frontier Hospital, Queenstown. Design. The study was an audit of ...

  3. Handwritten Newspapers on the Iowa Frontier, 1844-54.

    Science.gov (United States)

    Atwood, Roy Alden

    Journalism on the agricultural frontier of the Old Northwest territory of the United States was shaped by a variety of cultural forces and environmental factors and took on diverse forms. Bridging the gap between the two cultural forms of written correspondence and printed news was a third form: the handwritten newspaper. Between 1844 and 1854…

  4. A note on the assumed distributions in stochastic frontier models

    NARCIS (Netherlands)

    Meesters, Aljar

    2014-01-01

    Stochastic frontier models all need an assumption on the distributional form of the (in)efficiency component. Generally this efficiency component is assumed to be half normally, truncated normally, or exponentially distributed. This paper shows that the exponential distribution is, just like the

  5. Numerical Tools for the Bayesian Analysis of Stochastic Frontier Models

    NARCIS (Netherlands)

    Osiewalski, J.; Steel, M.F.J.

    1996-01-01

    In this paper we describe the use of modern numerical integration methods for making posterior inferences in composed error stochastic frontier models for panel data or individual cross-sections.Two Monte Carlo methods have been used in practical applications.We survey these two methods in some

  6. Dietary fibre: new frontiers for food and health

    National Research Council Canada - National Science Library

    Kamp, J. W. van der

    2010-01-01

    ... papers of the Dietary fibre analysis workshop and the HEALTHGRAIN Symposium Cereal grain fibre and health , both held in conjunction with DF09. This book is titled Dietary fibre- new frontiers for food and health . With the adoption - after decades of debate - of almost identical definitions of dietary fibre by Codex Alimentarius and the European Un...

  7. Enhanced Spectral Anisotropies Near the Proton-Cyclotron Scale: Possible Two-Component Structure in Hall-FLR MHD Turbulence Simulations

    Science.gov (United States)

    Ghosh, Sanjoy; Goldstein, Melvyn L.

    2011-01-01

    Recent analysis of the magnetic correlation function of solar wind fluctuations at 1 AU suggests the existence of two-component structure near the proton-cyclotron scale. Here we use two-and-one-half dimensional and three-dimensional compressible MHD models to look for two-component structure adjacent the proton-cyclotron scale. Our MHD system incorporates both Hall and Finite Larmor Radius (FLR) terms. We find that strong spectral anisotropies appear adjacent the proton-cyclotron scales depending on selections of initial condition and plasma beta. These anisotropies are enhancements on top of related anisotropies that appear in standard MHD turbulence in the presence of a mean magnetic field and are suggestive of one turbulence component along the inertial scales and another component adjacent the dissipative scales. We compute the relative strengths of linear and nonlinear accelerations on the velocity and magnetic fields to gauge the relative influence of terms that drive the system with wave-like (linear) versus turbulent (nonlinear) dynamics.

  8. MHD Stability of Free Boundary Toroidal Z Pinch

    Science.gov (United States)

    Sugisaki, Kiwamu

    1990-06-01

    The Magnetohydrodynamic (MHD) stability of a free boundary toroidal Z pinch plasma is investigated. Equilibrium field profiles are chosen so that μ is nearly uniform in the central region, μ and dμ/dr vanish on the boundary and Suydam’s criterion is satisfied throughout the plasma. The stability of the equilibrium is examined for the ratio b of the conducting wall radius to the plasma radius and plasma pressure. The stability of non-resonant ideal modes is determined mainly from the safty factor on the axis. Non-resonant modes are dominant for low plasma pressure, whereas resonant modes are dominant for high plasma pressure. Tearing modes are stable only for b below 1.04. The width of the magnetic islands produced from the tearing modes is evaluated. As b increases, overlap of the magnetic islands occurs over a wide area in the plasma.

  9. MHD simulations of coronal dark downflows considering thermal conduction

    Science.gov (United States)

    Zurbriggen, E.; Costa, A.; Esquivel, A.; Schneiter, M.; Cécere, M.

    2017-10-01

    While several scenarios have been proposed to explain supra-arcade downflows (SADs) observed descending through turbulent hot regions, none of them have systematically addressed the consideration of thermal conduction. The SADs are known to be voided cavities. Our model assumes that SADs are triggered by bursty localized reconnection events that produce non-linear waves generating the voided cavity. These subdense cavities are sustained in time because they are hotter than their surrounding medium. Due to the low density and large temperature values of the plasma we expect the thermal conduction to be an important process. Our main aim here is to study if it is possible to generate SADs in the framework of our model considering thermal conduction. We carry on 2D MHD simulations including anisotropic thermal conduction, and find that if the magnetic lines envelope the cavities, they can be isolated from the hot environment and be identified as SADs.

  10. Preface: MHD wave phenomena in the solar interior and atmosphere

    Science.gov (United States)

    Fedun, Viktor; Srivastava, A. K.

    2018-01-01

    The Sun is our nearest star and this star produces various plasma wave processes and energetic events. These phenomena strongly influence interplanetary plasma dynamics and contribute to space-weather. The understanding of solar atmospheric dynamics requires hi-resolution modern observations which, in turn, further advances theoretical models of physical processes in the solar interior and atmosphere. In particular, it is essential to connect the magnetohydrodynamic (MHD) wave processes with the small and large-scale solar phenomena vis-a-vis transport of energy and mass. With the advent of currently available and upcoming high-resolution space (e.g., IRIS, SDO, Hinode, Aditya-L1, Solar-C, Solar Orbiter), and ground-based (e.g., SST, ROSA, NLST, Hi-C, DKIST, EST, COSMO) observations, solar physicists are able to explore exclusive wave processes in various solar magnetic structures at different spatio-temporal scales.

  11. Numerical study for MHD peristaltic flow in a rotating frame.

    Science.gov (United States)

    Hayat, T; Zahir, Hina; Tanveer, Anum; Alsaedi, A

    2016-12-01

    The aim of present investigation is to model and analyze the magnetohydrodynamic (MHD) peristaltic transport of Prandtl fluid in a channel with flexible walls. The whole system consisting of fluid and channel are in a rotating frame of reference with uniform angular velocity. Viscous dissipation in thermal equation is not ignored. The channel boundaries satisfy the convective conditions in terms of temperature. The arising complicated problems are reduced in solvable form using large wavelength and small Reynolds number assumptions. Numerical solution for axial and secondary velocities, temperature and heat transfer coefficient are presented. Main emphasis is given to the outcome of rotation and material parameters of Prandtl fluid on the physical quantities of interest. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Structure and computation of two-dimensional incompressible extended MHD

    CERN Document Server

    Grasso, D; Abdelhamid, H M; Morrison, P J

    2016-01-01

    A comprehensive study of a reduced version of Lust's equations, the extended magnetohydrodynamic (XMHD) model obtained from the two-fluid theory for electrons and ions with the enforcement of quasineutrality, is given. Starting from the Hamiltonian structure of the fully three-dimensional theory, a Hamiltonian two-dimensional incompressible four-field model is derived. In this way energy conservation along with four families of Casimir invariants are naturally obtained. The construction facilitates various limits leading to the Hamiltonian forms of Hall, inertial, and ideal MHD, with their conserved energies and Casimir invariants. Basic linear theory of the four-field model is treated, and the growth rate for collisionless reconnection is obtained. Results from nonlinear simulations of collisionless tearing are presented and interpreted using, in particular normal fields, a product of the Hamiltonian theory that gives rise to simplified equations of motion.

  13. Tearing mode dynamics and sawtooth oscillation in Hall-MHD

    Science.gov (United States)

    Ma, Zhiwei; Zhang, Wei; Wang, Sheng

    2017-10-01

    Tearing mode instability is one of the most important dynamic processes in space and laboratory plasmas. Hall effects, resulted from the decoupling of electron and ion motions, could cause the fast development and perturbation structure rotation of the tearing mode and become non-negligible. We independently developed high accuracy nonlinear MHD code (CLT) to study Hall effects on the dynamic evolution of tearing modes with Tokamak geometries. It is found that the rotation frequency of the mode in the electron diamagnetic direction is in a good agreement with analytical prediction. The linear growth rate increases with increase of the ion inertial length, which is contradictory to analytical solution in the slab geometry. We further find that the self-consistently generated rotation largely alters the dynamic behavior of the double tearing mode and the sawtooth oscillation. National Magnetic Confinement Fusion Science Program of China under Grant No. 2013GB104004 and 2013GB111004.

  14. Stellarator expansion methods for MHD equilibrium and stability calculations

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, V.E.; Charlton, L.A.; Hicks, H.R.; Holmes, J.A.; Carreras, B.A.; Hender, T.C.; Garcia, L.

    1986-03-01

    Two methods for performing stellarator expansion, or average method, MHD calculations are described. The first method includes the calculation of vacuum, equilibrium, and stability, using the Greene and Johnson stellarator expansion in which the equilibrium is reduced to a 2-D problem by averaging over the geometric toroidal angle in real space coordinates. In the second method, the average is performed in a system of vacuum magnetic coordinates. Both methods are implemented to utilize realistic vacuum field information, making them applicable to configuration studies and machine design, as well as to basic research. Illustrative examples are presented to detail the sensitivities of the calculations to physical parameters and to show numerical convergence and the comparison of these methods with each other and with other methods.

  15. The SOL width and the MHD interchange instability in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Kerner, W. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Pogutse, O. [Kurchatov institute, Moscow (Russian Federation)

    1994-07-01

    Instabilities in the SOL plasma can strongly influence the SOL plasma behaviour and in particular the SOL width. The SOL stability analysis shows that there exists a critical ratio of the thermal energy and the magnetic energy. If the SOL beta is greater than this critical value, the magnetic field cannot prevent the plasma displacement and a strong MHD instability in the SOL occurs. In the opposite case only slower resistive instabilities can develop. A theoretical investigation of the SOL plasma stability is presented for JET single-null and double-null divertor configurations. The dependence of the stability threshold on the SOL beta and on the sheath resistance is established. Applying a simple mixing length argument gives the scaling of the SOL width. 5 refs., 2 figs.

  16. Transpiration cooled electrodes and insulators for MHD generators

    Science.gov (United States)

    Hoover, Jr., Delmer Q.

    1981-01-01

    Systems for cooling the inner duct walls in a magnetohydrodynamic (MHD) generator. The inner face components, adjacent the plasma, are formed of a porous material known as a transpiration material. Selected cooling gases are transpired through the duct walls, including electrically insulating and electrode segments, and into the plasma. A wide variety of structural materials and coolant gases at selected temperatures and pressures can be utilized and the gases can be drawn from the generation system compressor, the surrounding environment, and combustion and seed treatment products otherwise discharged, among many other sources. The conduits conducting the cooling gas are electrically insulated through low pressure bushings and connectors so as to electrically isolate the generator duct from the ground.

  17. Synchrotron Radiation Maps from Relativistic MHD Jet Simulations

    Directory of Open Access Journals (Sweden)

    Dimitrios Millas

    2017-11-01

    Full Text Available Relativistic jets from active galactic nuclei (AGN often display a non-uniform structure and are, under certain conditions, susceptible to a number of instabilities. An interesting example is the development of non-axisymmetric, Rayleigh-Taylor type instabilities in the case of differentially rotating two-component jets, with the toroidal component of the magnetic field playing a key role in the development or suppression of these instabilities. We have shown that higher magnetization leads to stability against these non-axisymmetric instabilities. Using ray-casting on data from relativistic MHD simulations of two-component jets, we now investigate the effect of these instabilities on the synchrotron emission pattern from the jets. We recover many well known trends from actual observations, e.g., regarding the polarization fraction and the distribution of the position angle of the electric field, in addition to a different emitting region, depending on the stability of the jet.

  18. Impact of measurement uncertainties on universal scaling of MHD turbulence

    Science.gov (United States)

    Gogoberidze, G.; Chapman, S. C.; Hnat, B.; Dunlop, M. W.

    2012-10-01

    Quantifying the scaling of fluctuations in the solar wind is central to testing predictions of turbulence theories. We study spectral features of Alfvénic turbulence in fast solar wind. We propose a general, instrument-independent method to estimate the uncertainty in velocity fluctuations obtained by in situ satellite observations in the solar wind. We show that when the measurement uncertainties of the velocity fluctuations are taken into account the less energetic Elsasser spectrum obeys a unique power law scaling throughout the inertial range as prevailing theories of magnetohydrodynamic (MHD) turbulence predict. Moreover, in the solar wind interval analysed, the two Elsasser spectra are observed to have the same scaling exponent γ = -1.54 throughout the inertial range.

  19. Realistic radiative MHD simulation of a solar flare

    Science.gov (United States)

    Rempel, Matthias D.; Cheung, Mark; Chintzoglou, Georgios; Chen, Feng; Testa, Paola; Martinez-Sykora, Juan; Sainz Dalda, Alberto; DeRosa, Marc L.; Viktorovna Malanushenko, Anna; Hansteen, Viggo H.; De Pontieu, Bart; Carlsson, Mats; Gudiksen, Boris; McIntosh, Scott W.

    2017-08-01

    We present a recently developed version of the MURaM radiative MHD code that includes coronal physics in terms of optically thin radiative loss and field aligned heat conduction. The code employs the "Boris correction" (semi-relativistic MHD with a reduced speed of light) and a hyperbolic treatment of heat conduction, which allow for efficient simulations of the photosphere/corona system by avoiding the severe time-step constraints arising from Alfven wave propagation and heat conduction. We demonstrate that this approach can be used even in dynamic phases such as a flare. We consider a setup in which a flare is triggered by flux emergence into a pre-existing bipolar active region. After the coronal energy release, efficient transport of energy along field lines leads to the formation of flare ribbons within seconds. In the flare ribbons we find downflows for temperatures lower than ~5 MK and upflows at higher temperatures. The resulting soft X-ray emission shows a fast rise and slow decay, reaching a peak corresponding to a mid C-class flare. The post reconnection energy release in the corona leads to average particle energies reaching 50 keV (500 MK under the assumption of a thermal plasma). We show that hard X-ray emission from the corona computed under the assumption of thermal bremsstrahlung can produce a power-law spectrum due to the multi-thermal nature of the plasma. The electron energy flux into the flare ribbons (classic heat conduction with free streaming limit) is highly inhomogeneous and reaches peak values of about 3x1011 erg/cm2/s in a small fraction of the ribbons, indicating regions that could potentially produce hard X-ray footpoint sources. We demonstrate that these findings are robust by comparing simulations computed with different values of the saturation heat flux as well as the "reduced speed of light".

  20. Condensation and deposition of seed in the MHD bottoming plant

    Energy Technology Data Exchange (ETDEWEB)

    Im, K. H.; Patten, J.; Johnson, T. R.; Tempelmeyer, K.

    1979-01-01

    The computer models of slag vapor nucleation and particle deposition have been extended to predict the growth and deposition of seed particles in the steam and air heater sections of the MHD bottoming plant. The model represents a hot combustion gas stream, which contains vaporized seed and entrained slag particles of a selected initial size distribution, flowing through a bank of cooled tubes. The energy balance includes convective and radiant heat transfer to the cool surfaces. The material balance for the condensible species considers convective mass transport of seed vapor to cool surfaces, and the deposition of particles on cooled surfaces by thermophoresis. The analyses provide the bases for design trade-off studies of steam tube size and spacing, gas velocity, and system configuration to optimize the effectiveness and cost of the steam plant. In the absence of entrained slag particles, sample calculations indicated that, as the gas is cooled in passing through a tube bank, the bulk of the seed vapor condenses in the gas stream to form particles with diameters in the range of 0.02 to 0.2 ..mu..m. In the presence of the submicron slag particles formed upstream in the MHD diffuser, the largest fraction of the seed vapor condenses on the existing entrained particles, causing them to grow to a size in the range of approximately one micron. In both cases, these particles are deposited on heat exchange surfaces throughout the heat recovery system and a large fraction is present in the cool combustion gas entering the exhaust gas clean-up system.

  1. A randomized controlled trial of long term effect of BCM guided fluid management in MHD patients (BOCOMO study): rationales and study design.

    Science.gov (United States)

    Liu, Li; Long, Gang; Ren, Jianwei; Li, Jijun; Xu, Jinsheng; Lei, Jinghong; Li, Mao; Qiu, Moyan; Yuan, Ping; Sun, Weiming; Lin, Shan; Liu, Wenjun; Sun, Yi; Ma, Yingchun; Mao, Yonghui; Shen, Yulan; Zuo, Li

    2012-09-25

    considerations related to the endpoints, sample size, inclusion criteria, exclusion criteria and so on. For example, annual mortality of Beijing MHD patients was around 10%. To reach statistical significance, the sample size will be very large. By using composite endpoint, the sample size becomes reasonable and feasible. Limiting inclusion to patients with urine volume less than 800 ml/day the day before dialysis session will limit confounding due to residual renal function effects on the measured parameters. Patients who had received BIS measurement within 3 months prior to enrolment are excluded as data from such measurements might lead to protocol violation. Although not all patients enrolled will be incident patients, we will record the vintage of dialysis in the multivariable analysis.

  2. A randomized controlled trial of long term effect of BCM guided fluid management in MHD patients (BOCOMO study: rationales and study design

    Directory of Open Access Journals (Sweden)

    Liu Li

    2012-09-01

    that aim, the study was designed with very careful important considerations related to the endpoints, sample size, inclusion criteria, exclusion criteria and so on. For example, annual mortality of Beijing MHD patients was around 10%. To reach statistical significance, the sample size will be very large. By using composite endpoint, the sample size becomes reasonable and feasible. Limiting inclusion to patients with urine volume less than 800 ml/day the day before dialysis session will limit confounding due to residual renal function effects on the measured parameters. Patients who had received BIS measurement within 3 months prior to enrolment are excluded as data from such measurements might lead to protocol violation. Although not all patients enrolled will be incident patients, we will record the vintage of dialysis in the multivariable analysis. Trial registration Current Controlled Trials NCT01509937

  3. Shifting frontiers of transcendence in theology, philosophy and science

    Directory of Open Access Journals (Sweden)

    Cornelius W. du Toit

    2011-04-01

    Full Text Available This article dealt cursorily with developments in theology, philosophy and the sciences that have contributed to what one might call horizontal transcendence. The premise is that humans have evolved into beings that are wired for transcendence. Transcendence is described in terms of the metaphor of frontiers and frontier posts. Although the frontiers of transcendence shift according to the insights, understanding and needs of every epoch and world view, it remains transcendent, even in its immanent mode. Diverse perceptions of that frontier normally coexist in every era and we can only discern a posteriori which was the dominant one. Frontiers are fixed with reference to the epistemologies, notions of the subject and power structures of a given era. From a theological point of view, encounter with the transcendent affords insight, not into the essence of transcendence, but into human self-understanding and understanding of our world. Transcendence enters into the picture when an ordinary human experience acquires a depth and an immediacy that are attributed to an act of God. In philosophy, transcendence evolved from a noumenal metaphysics focused on the object (Plato, via emphasis on the epistemological structure and limits of the knowing subject (Kant and an endeavour to establish a dynamic subject-object dialectics (Hegel, to the assimilation of transcendence into human existence (Heidegger. In the sciences certain developments opened up possibilities for God to act in non-interventionist ways. The limitations of such an approach are considered, as well as promising new departures – and their limitations – in the neurosciences. From all of this I conclude that an immanent-transcendent approach is plausible for our day and age.

  4. A study on the fusion reactor - Numerical analyses of MHD equilibrium and= edge plasma transport in tokamak fusion reactor with divertor configurations

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sang Hee; Kang, Kyung Doo; Ryu, Ji Myung; Kim, Deok Kyu; Chung, TaeKyun; Chung, Mo Se [Seoul National University, Seoul (Korea, Republic of); Cho, Su Won [Kyungki University, Suwon (Korea, Republic of)

    1995-08-01

    In the present project for developing the numerical codes of 2-D MHD equilibrium, edge plasma transport and neutral particle transport for the tokamak plasmas, we computed the MHD equilibria of single and double null configurations and determined the external coil currents and the plasma parameters used for operation and control data. Also we numerically acquired the distributions of edge plasma parameters in poloidal and radial directions= and the design-related values according to the various operating conditions using the developed plasma transport code. Furthermore, a neutral particle transport code for the edge region is developed and them used for the analysis of the neutral particle behavior yielding the source terms in the fluid transport equations, and expected to supply the input parameters for the edge plasma transport code. 53 refs., 12 tabs., 44 figs. (author)

  5. Technical support for open-cycle MHD program. Progress report, July-September 1979

    Energy Technology Data Exchange (ETDEWEB)

    Berry, G.F. (ed.)

    1981-06-01

    The support program for open-cycle MHD at the Argonne National Laboratory consists of developing the analytical tools needed for investigation of the performance of the major components in the combined-cycle MHD/steam power system. The analytical effort is centered on the primary components of the system that are unique to MHD and, also, in the integration of these analytical models into a mode for the entire power-producing system. The present project activities include modeling of the secondary combustor, generator, seed deposition, and formation and decomposition of NO. Costing models were developed and used to assess the effect of parameter changes on cost of electricity. Parametric studies were performed to evaluate the performance of the U-25B generator and to support the design of the US U-25B generator. Refinements and improvements to the MHD systems code and executive program are described.

  6. MHD Simulations of Magnetospheric Accretion, Ejection and Plasma-field Interaction

    Directory of Open Access Journals (Sweden)

    Romanova M. M.

    2014-01-01

    Full Text Available We review recent axisymmetric and three-dimensional (3D magnetohydrodynamic (MHD numerical simulations of magnetospheric accretion, plasma-field interaction and outflows from the disk-magnetosphere boundary.

  7. Advanced Numerical Methods for Three-Dimensional Parallel Hybrid MHD/PIC

    National Research Council Canada - National Science Library

    McCrory, Robert

    1996-01-01

    .... The main conclusion of our study is that computationally efficient and physically sound description of nonsteady plasmas typical for these applications is possible using the advanced hybrid MHD/PIC...

  8. Variational approach to low-frequency kinetic-MHD in the current coupling scheme

    CERN Document Server

    Burby, J W

    2016-01-01

    Hybrid kinetic-MHD models describe the interaction of an MHD bulk fluid with an ensemble of hot particles, which is described by a kinetic equation. When the Vlasov description is adopted for the energetic particles, different Vlasov-MHD models have been shown to lack an exact energy balance, which was recently recovered by the introduction of non-inertial force terms in the kinetic equation. These force terms arise from fundamental approaches based on Hamiltonian and variational methods. In this work we apply Hamilton's variational principle to formulate new current-coupling kinetic-MHD models in the low-frequency approximation (i.e. large Larmor frequency limit). More particularly, we formulate current-coupling hybrid schemes, in which energetic particle dynamics are expressed in either guiding-center or gyrocenter coordinates.

  9. Decay of MHD-scale Kelvin-Helmholtz vortices mediated by parasitic electron dynamics.

    Science.gov (United States)

    Nakamura, T K M; Hayashi, D; Fujimoto, M; Shinohara, I

    2004-04-09

    We have simulated nonlinear development of MHD-scale Kelvin-Helmholtz (KH) vortices by a two-dimensional two-fluid system including finite electron inertial effects. In the presence of moderate density jump across a shear layer, in striking contrast to MHD results, MHD KH vortices are found to decay by the time one eddy turnover is completed. The decay is mediated by smaller vortices that appear within the parent vortex and stays effective even when the shear layer width is made larger. It is shown that the smaller vortices are basically of MHD nature while the seeding for these is achieved by the electron inertial effect. Application of the results to the magnetotail boundary layer is discussed.

  10. Scramjet Inlet Control by Off-Body Energy Addition and MHD Deceleration

    National Research Council Canada - National Science Library

    Macheret, Sergey O; Shneider, Mikhail N; Miles, Richard B; Van Wie, David

    2003-01-01

    Analysis of interaction parameter for MHD control of cold hypersonic flows with external ionization shows that significant interaction can be achieved with energy-efficient ionization by electron beams...

  11. Parametric study of potential early commercial power plants Task 3-A MHD cost analysis

    Science.gov (United States)

    1983-01-01

    The development of costs for an MHD Power Plant and the comparison of these costs to a conventional coal fired power plant are reported. The program is divided into three activities: (1) code of accounts review; (2) MHD pulverized coal power plant cost comparison; (3) operating and maintenance cost estimates. The scope of each NASA code of account item was defined to assure that the recently completed Task 3 capital cost estimates are consistent with the code of account scope. Improvement confidence in MHD plant capital cost estimates by identifying comparability with conventional pulverized coal fired (PCF) power plant systems is undertaken. The basis for estimating the MHD plant operating and maintenance costs of electricity is verified.

  12. Chemical reaction in MHD flow past a vertical plate with mass ...

    African Journals Online (AJOL)

    Corresponding Author: e-mail: rajputneetulko@gmail.com. Abstract. Chemical reaction plays an important role in MHD flow. It has industrial applications, such as design of chemical processing equipments, food processing and cooling towers etc.

  13. Closed cycle MHD power generation experiments in the NASA Lewis facility

    Science.gov (United States)

    Sovie, R. J.; Nichols, L. D.

    1974-01-01

    Discussion of the performance improvements achieved through some modifications made in the closed cycle MHD facility. These modifications include a redesign of the MHD duct interior, addition of mixing bars, increased electrical isolation, and experimentation with various cesium seed vaporization and injection techniques. Uniform Faraday and Hall voltage profiles were obtained, and the Faraday open circuit voltage varied from 90 to 100% of the ideal uBh.

  14. Exact solutions for MHD flow of couple stress fluid with heat transfer

    Directory of Open Access Journals (Sweden)

    Najeeb Alam Khan

    2016-01-01

    Full Text Available This paper aims at presenting exact solutions for MHD flow of couple stress fluid with heat transfer. The governing partial differential equations (PDEs for an incompressible MHD flow of couple stress fluid are reduced to ordinary differential equations by employing wave parameter. The methodology is implemented for linearizing the flow equations without extra transformation and restrictive assumptions. Comparison is made with the result obtained previously.

  15. Methodology to assess the effects of magnetohydrodynamic electromagnetic pulse (MHD-EMP) on power systems

    Energy Technology Data Exchange (ETDEWEB)

    Legro, J.R.; Abi-Samra, N.C.; Crouse, J.C.; Tesche, F.M.

    1985-01-01

    This paper summarizes a method to evaluate the possible effects of magnetohydrodynamic-electromagnetic pulse (MHD-EMP) on power systems. This method is based on the approach adapted to study the impact of geomagnetic storms on power systems. The paper highlights the similarities and differences between the two phenomena. Also presented are areas of concern which are anticipated from MHD-EMP on the overall system operation. 12 refs., 1 fig.

  16. Existencia global y estabilidad de soluciones para las ecuaciones de la magnetohidrodinámica (MHD)

    OpenAIRE

    Galeano Delgado, Juan Gabriel

    2009-01-01

    En este trabajo se demuestra la estabilidad de soluciones estacionarias para las ecuaciones de la MHD. Inicialmente se prueba que el problema estacionario para las Ecuaciones de la MHD, denido en un dominio acotado de R3; tiene una unica solucion fuerte, en el espacio de Lebesgue L3() Lm(), cuando m > 3=2. En segunda instancia se muestra que este tipo de soluciones estacionarias son exponencialmente estables, y se obtienen tasas de decaimiento rapido. Como consecuencia del res...

  17. Expected IPS variations due to a disturbance described by a 3-D MHD model

    Science.gov (United States)

    Tappin, S. J.; Dryer, M.; Han, S. M.; Wu, S. T.

    1988-01-01

    The variations of interplanetary scintillation due to a disturbance described by a three-dimensional, time-dependent, MHD model of the interplanetary medium are calculated. The resulting simulated IPS maps are compared with observations of real disturbances and it is found that there is some qualitative agreement. It is concluded that the MHD model with a more realistic choice of input conditions would probably provide a useful description of many interplanetary disturbances.

  18. Magnetohydrodynamics (MHD) Engineering Test Facility (ETF) 200 MWe power plant. Design Requirements Document (DRD)

    Science.gov (United States)

    Rigo, H. S.; Bercaw, R. W.; Burkhart, J. A.; Mroz, T. S.; Bents, D. J.; Hatch, A. M.

    1981-01-01

    A description and the design requirements for the 200 MWe (nominal) net output MHD Engineering Test Facility (ETF) Conceptual Design, are presented. Performance requirements for the plant are identified and process conditions are indicated at interface stations between the major systems comprising the plant. Also included are the description, functions, interfaces and requirements for each of these major systems. The lastest information (1980-1981) from the MHD technology program are integrated with elements of a conventional steam electric power generating plant.

  19. Relativistic particle transport in extragalactic jets: I. Coupling MHD and kinetic theory

    OpenAIRE

    Casse, F.; Marcowith, A.

    2003-01-01

    Multidimensional magneto-hydrodynamical (MHD) simulations coupled with stochastic differential equations (SDEs) adapted to test particle acceleration and transport in complex astrophysical flows are presented. The numerical scheme allows the investigation of shock acceleration, adiabatic and radiative losses as well as diffusive spatial transport in various diffusion regimes. The applicability of SDEs to astrophysics is first discussed in regards to the different regimes and the MHD code spat...

  20. Roads as Drivers of Change: Trajectories across the Tri‑National Frontier in MAP, the Southwestern Amazon

    Directory of Open Access Journals (Sweden)

    Grenville Barnes

    2011-05-01

    Full Text Available Regional studies of land cover change are often limited by available data and in terms of comparability across regions, by the transferability of methods. This research addresses the role of roads and infrastructure improvements across a tri-national frontier region with similar climatic and biophysical conditions but very different trajectories of forest clearing. The standardization of methodologies and the extensive spatial and temporal framework of the analysis are exciting as they allow us to monitor a dynamic region with global significance as it enters an era of increased road connectivity and massive potential forest loss. Our study region is the “MAP” frontier, which covers Madre de Dios in Peru, Acre in Brazil, and Pando in Bolivia. This tri-national frontier is being integrated into the global economy via the paving of the Inter-Oceanic Highway which links the region to ports in the Atlantic and Pacific, constituting a major infrastructure change within just the last decade. Notably, there are differences in the extent of road paving among the three sides of the tri-national frontier, with paving complete in Acre, underway in Madre de Dios, and incipient in Pando. Through a multi-temporal analysis of land cover in the MAP region from 1986 to 2005, we found that rates of deforestation differ across the MAP frontier, with higher rates in Acre, followed by Madre de Dios and the lowest rates in Pando, although the dominant land cover across the region is still stable forest cover (89% overall. For all dates in the study period, deforestation rates drop with distance from major roads although the distance before this drop off appears to relate to development, with Acre influencing forests up to around 45 km out, Madre de Dios to about 18 km out and less of a discernable effect or distance value in Pando. As development occurs, the converted forest areas saturate close to roads, resulting in increasing rates of deforestation at further

  1. Further validation of liquid metal MHD code for unstructured grid based on OpenFOAM

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jingchao; Chen, Hongli, E-mail: hlchen1@ustc.edu.cn; He, Qingyun; Ye, Minyou

    2015-11-15

    Highlights: • Specific correction scheme has been adopted to revise the calculating result for non-orthogonal meshes. • The developed MHD code based on OpenFOAM platform has been validated by benchmark cases under uniform and non-uniform magnetic field in round and rectangular ducts. • ALEX experimental results have been used to validate the MHD code based on OpenFOAM. - Abstract: In fusion liquid metal blankets, complex geometries involving contractions, expansions, bends, manifolds are very common. The characteristics of liquid metal flow in these geometries are significant. In order to extend the magnetohydrodynamic (MHD) solver developed on OpenFOAM platform to be applied in the complex geometry, the MHD solver based on unstructured meshes has been implemented. The adoption of non-orthogonal correction techniques in the solver makes it possible to process the non-orthogonal meshes in complex geometries. The present paper focused on the validation of the code under critical conditions. An analytical solution benchmark case and two experimental benchmark cases were conducted to validate the code. Benchmark case I is MHD flow in a circular pipe with arbitrary electric conductivity of the walls in a uniform magnetic field. Benchmark cases II and III are experimental cases of 3D laminar steady MHD flow under fringing magnetic field. In all these cases, the numerical results match well with the benchmark cases.

  2. Effects of MHD slow shocks propagating along magnetic flux tubes in a dipole magnetic field

    Directory of Open Access Journals (Sweden)

    N. V. Erkaev

    2002-01-01

    Full Text Available Variations of the plasma pressure in a magnetic flux tube can produce MHD waves evolving into shocks. In the case of a low plasma beta, plasma pressure pulses in the magnetic flux tube generate MHD slow shocks propagating along the tube. For converging magnetic field lines, such as in a dipole magnetic field, the cross section of the magnetic flux tube decreases enormously with increasing magnetic field strength. In such a case, the propagation of MHD waves along magnetic flux tubes is rather different from that in the case of uniform magnetic fields. In this paper, the propagation of MHD slow shocks is studied numerically using the ideal MHD equations in an approximation suitable for a thin magnetic flux tube with a low plasma beta. The results obtained in the numerical study show that the jumps in the plasma parameters at the MHD slow shock increase greatly while the shock is propagating in the narrowing magnetic flux tube. The results are applied to the case of the interaction between Jupiter and its satellite Io, the latter being considered as a source of plasma pressure pulses.

  3. Robert R. Wilson Prize for Achievement in the Physics of Particle Accelerators Lecture: Frontiers of FEL Physics and Technology

    Science.gov (United States)

    Madey, John M. J.

    2012-03-01

    For much of the past 40 years, efforts to advance the capabilities of FELs have focussed on the frontiers of operation at high average power and short wavelengths with impressive and gratifying results. But a number of potentially important additional frontiers remain to be explored. I will briefly describe several of the new areas in which we have worked relating to the exploitation of boundary conditions to enhance oscillator phase coherence and stability, the exploitation of phase coherence to reduce the quantum fluctuations in amplitude of the coherent harmonics, the elucidation of the classical Wheeler-Feynman coherent radiation reaction force in single pass radiation sources, the development of the precision, robust high peak and average power optical elements needed for the reliable operation of these sources and the application of these advances to the development of optimized inverse-Compton x-ray and gamma ray sources.

  4. Exploring smoking, mental health and smoking-related disease in a nationally representative sample of older adults in Ireland – A retrospective secondary analysis.

    OpenAIRE

    Burns, Annette; Strawbridge, Judith; Clancy, Luke; Doyle, Frank

    2017-01-01

    Objective Smoking is the leading preventable cause of death among individuals with mental health difficulties (MHD). The aim of the current study was to determine the impact of smoking on the physical health of older adults with MHD in Ireland and to explore the extent to which smoking mediated or moderated associations between MHD and smoking-related diseases. Methods Cross-sectional analysis of a nationally representative sample of 8175 community-dwelling adults aged 50 and over from The I...

  5. Formation and Evolution of Target Patterns in Cahn-Hilliard Flows: An Extension of the Flux Expulsion Studies in MHD

    Science.gov (United States)

    Fan, Xiang; P H Diamond Collaboration; Luis Chacon Collaboration

    2017-10-01

    Spinodal decomposition is a second order phase transition for a binary liquid mixture to evolve from a miscible phase (e.g., water + alcohol) to two co-existing phases (e.g., water + oil). The Cahn-Hilliard model for spinodal decomposition is analogous to 2D MHD. We study the evolution of the concentration field in a single eddy in the 2D Cahn-Hilliard system to better understand scalar mixing processes in that system. This study extends investigations of the classic studies of flux expulsion in 2D MHD and homogenization of potential vorticity in 2D fluids. Simulation results show that there are three stages in the evolution: (A) formation of a ``jelly roll'' pattern, for which the concentration field is constant along spirals; (B) a change in isoconcentration contour topology; and (C) formation of a target pattern, for which the isoconcentration contours follow concentric annuli. In the final target pattern stage, the isoconcentration bands align with stream lines. The results indicate that the target pattern is a metastable state. Band merger process continues on a time scale exponentially long relative to the eddy turnover time. The band merger process resembles step merger in drift-ZF staircases. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, under Award Number DE-FG02-04ER54738.

  6. Experimental Bullard-von Karman dynamo: MHD saturated regimes

    Science.gov (United States)

    Miralles, Sophie; Plihon, Nicolas; Pinton, Jean-François

    2014-05-01

    The dynamo instability, converting kinetic energy into magnetic energy, creates the magnetic fields of many astrophysical bodies for which the flows are highly turbulent. Those turbulent fluctuations restricts the range of parameters of numerical and theoretical predictions. As laboratory experiments are closer from natural parameters, this approach is favored in this work. In the past decades, dynamo action has been observed in experiments involving laminar flows [1] or fully turbulent flows [2] in liquid sodium. Nevertheless, the saturation of the velocity field by the Lorentz force due to the dynamo magnetic field is weak in those experiment because the control parameter is always close to the threshold of the instability (which is not the case in astrophysical situations). The details of the mechanism of the back reaction of Lorentz force on the flow are not known. We present here an experimental semi-synthetic dynamo, for which a fluid turbulent induction mechanism ('omega' effect) is associated to an external amplification applying a current into a pair of coils. The flow, called von-Karman, is produced by the counter rotation of two coaxial propellers in a cylindrical tank filled with liquid gallium. The resulting flow is highly turbulent (Re > 10 ^ 5). The amplification, mimicking a turbulent 'alpha' effect, allow to observe the dynamo instability at low magnetic Reynolds number (Rm ~ 2), far below the threshold of natural homogeneous dynamo. This experiment reaches non linear regimes, for which the saturation is a MHD process, at control parameter several times the critical value. The instability grows through an on-off intermittent regime evolving into a full MHD saturated regime for which the Lorentz force is in balance with the inertial one. The power budget is strongly modified by the dynamo magnetic field and we give an insight of the estimated rate of conversion of kinetic energy into magnetic one from experimental data. Very rich regimes such as

  7. The Belle II experiment: fundamental physics at the flavor frontier

    CERN Document Server

    de la Cruz, Ivan Heredia

    2016-01-01

    After the major success of B-factories to establish the CKM mechanism and its proven potential to search for new physics, the Belle II experiment will continue exploring the physics at the flavor frontier over the next years. Belle II will collect 50 times more data than its predecessor, Belle, and allow for various precision measurements and searches of rare decays and particles. This paper introduces the B-factory concept and the flavor frontier approach to search for new physics. It then describes the SuperKEKB accelerator and the Belle II detector, as well as some of the physics that will be analyzed in Belle II, concluding with the experiment status and schedule.

  8. Facilities for the Energy Frontier of Nuclear Physics

    CERN Document Server

    Jowett, John M

    2011-01-01

    The Relativistic Heavy Ion Collider at BNL has been exploring the energy frontier of nuclear physics since 2001. Its performance, flexibility and continued innovative upgrading can sustain its physics output for years to come. Now, the Large Hadron Collider at CERN is about to extend the frontier energy of laboratory nuclear collisions by more than an order of magnitude. In the coming years, its physics reach will evolve towards still higher energy, luminosity and varying collision species, within performance bounds set by accelerator technology and by nuclear physics itself. Complementary high-energy facilities will include fixed-target collisions at the CERN SPS, the FAIR complex at GSI and possible electron-ion colliders based on CEBAF at JLAB, RHIC at BNL or the LHC at CERN.

  9. Working Group Report: Computing for the Intensity Frontier

    Energy Technology Data Exchange (ETDEWEB)

    Rebel, B.; Sanchez, M. C.; Wolbers, S.

    2013-10-25

    This is the report of the Computing Frontier working group on Lattice Field Theory prepared for the proceedings of the 2013 Community Summer Study ("Snowmass"). We present the future computing needs and plans of the U.S. lattice gauge theory community and argue that continued support of the U.S. (and worldwide) lattice-QCD effort is essential to fully capitalize on the enormous investment in the high-energy physics experimental program. We first summarize the dramatic progress of numerical lattice-QCD simulations in the past decade, with some emphasis on calculations carried out under the auspices of the U.S. Lattice-QCD Collaboration, and describe a broad program of lattice-QCD calculations that will be relevant for future experiments at the intensity and energy frontiers. We then present details of the computational hardware and software resources needed to undertake these calculations.

  10. EDITORIAL: Frontiers in semiconductor-based devices Frontiers in semiconductor-based devices

    Science.gov (United States)

    Krishna, Sanjay; Phillips, Jamie; Ghosh, Siddhartha; Ma, Jack; Sabarinanthan, Jayshri; Stiff-Roberts, Adrienne; Xu, Jian; Zhou, Weidong

    2009-12-01

    This special cluster of Journal of Physics D: Applied Physics reports proceedings from the Frontiers in Semiconductor-Based Devices Symposium, held in honor of the 60th birthday of Professor Pallab Bhattacharya by his former doctoral students. The symposium took place at the University of Michigan, Ann Arbor on 6-7 December 2009. Pallab Bhattacharya has served on the faculty of the Electrical Engineering and Computer Science Department at the University of Michigan, Ann Arbor for 25 years. During this time, he has made pioneering contributions to semiconductor epitaxy, characterization of strained heterostructures, self-organized quantum dots, quantum-dot optoelectronic devices, and integrated optoelectronics. Professor Bhattacharya has been recognized for his accomplishments by membership of the National Academy of Engineering, by chaired professorships (Charles M Vest Distinguished University Professor and James R Mellor Professor of Engineering), and by selection as a Fellow of the IEEE, among numerous other honors and awards. Professor Bhattacharya has also made remarkable contributions in education, including authorship of the textbook Semiconductor Optoelectronic Devices (Prentice Hall, 2nd edition) and the production of 60 PhD students (and counting). In fact, this development of critical human resources is one of the biggest impacts of Professor Bhattacharya's career. His guidance and dedication have shaped the varied professional paths of his students, many of whom currently enjoy successful careers in academia, industry, and government around the world. This special cluster acknowledges the importance of Professor Bhattacharya's influence as all of the contributions are from his former doctoral students. The symposium reflects the significant impact of Professor Bhattacharya's research in that the topics span diverse, critical research areas, including: semiconductor lasers and modulators, nanoscale quantum structure-based devices, flexible CMOS

  11. AHP 45: REVIEW: FOUNDING AN EMPIRE ON INDIA'S NORTH-EASTERN FRONTIERS 1790-1840

    Directory of Open Access Journals (Sweden)

    Hilary Howes

    2017-03-01

    Full Text Available This thoroughly researched and carefully constructed monograph focuses on what is now north-eastern India, an irregularly-shaped region joined only by a narrow neck of land to the remainder of the Indian subcontinent and jostled (or nestled, depending on one's point of view between Bangladesh, Bhutan, Myanmar, Nepal, and Tibet. Crucially, author Gunnel Cederlöf argues, this representation of northeast India on modern maps - an island in constant danger of drifting away from mainland India, held in place only by the "Chicken's Neck" or Siliguri Corridor - bears no relation to the way in which this region was imagined by the British East India Company (EIC in the late eighteenth and early nineteenth centuries. Having obtained revenuefarming rights and judicial duties over the North-Eastern Frontier, as it was then known, through a 1765 diwani grant from the Great Mughal in Delhi, the EIC aspired first and foremost to revive the administration of revenue in the region, adding a monopoly in territory to their existing monopolies in the eastern trade. Given these primarily commercial interests, it should come as no surprise that the EIC's map-makers, their eyes fixed on the web of lucrative trade routes crisscrossing the region, homed in on the North-Eastern Frontier as the central point in "a synoptic vision that connected Bengal to China" (72. ...

  12. Frontiers of the food-energy-water trilemma: Sri Lanka as a microcosm of tradeoffs

    Science.gov (United States)

    Perrone, Debra; Hornberger, George

    2016-01-01

    Food, energy, and water are three critical resources for humanity. As climate variability, population growth, and lifestyle changes amplify the stress placed on each of the resources, the interrelationships among food, energy, and water systems become more pronounced. Political conflict, social and cultural norms, and spatial and temporal distribution of the resources add additional layers of complexity. It is in this context that the significance of understanding the impacts of water scarcity on the decisions around food and energy productions has emerged. Our work establishes tradeoff frontiers (TFs) as a method useful in illustrating the system-level tradeoffs between allocating water for food and water for energy. This paper illustrates how TFs can be used to (1) show how scarcity in water resources affects the tradeoffs between food and energy and (2) explore the political and social constraints that can move production away from what is feasible technically. We use Sri Lanka, a country where water resources are variable both in space and time and a country with relatively self-contained energy and agricultural sectors, as a microcosm of the food security, energy security, and water security trilemma. Nevertheless, our application of tradeoff frontiers is applicable widely to other systems.

  13. International Conference on Frontiers of Intelligent Computing : Theory and Applications

    CERN Document Server

    Bhateja, Vikrant; Udgata, Siba; Pattnaik, Prasant

    2017-01-01

    The book is a collection of high-quality peer-reviewed research papers presented at International Conference on Frontiers of Intelligent Computing: Theory and applications (FICTA 2016) held at School of Computer Engineering, KIIT University, Bhubaneswar, India during 16 – 17 September 2016. The book presents theories, methodologies, new ideas, experiences and applications in all areas of intelligent computing and its applications to various engineering disciplines like computer science, electronics, electrical and mechanical engineering.

  14. Taking global scale data handling to the Fermilab intensity frontier

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, Adam L. [Fermilab; Illingworth, Robert A. [Fermilab; Mengel, Marc [Fermilab; Norman, Andrew J. [Fermilab

    2012-01-01

    SAM is a comprehensive data management system used by the Tevatron Run II experiments with great success. The newest experiments at Fermilab, the Intensity Frontier experiments, are currently lacking such a system. In these proceedings, the advantages of using SAM for these experiments is discussed. Two improvements to SAM, namely SAMWeb and SAMfs are described. These improvements will make SAM much easier to integrate, deploy, maintain, and use.

  15. Nutrition Frontiers - Spring 2017 | Division of Cancer Prevention

    Science.gov (United States)

    Volume 8, Issue 2 Dear Colleague, The spring issue of Nutrition Frontiers showcases the calcium/magnesium intake ratio in colorectal adenoma, the role of PPARγ in metabolism and reproduction, and the effects of time-restricted feeding on metabolic parameters. Meet our spotlight investigator, Dr. Maria Cruz-Correa, and her research on gut bacterial genes, diet, and colorectal neoplasia. Learn about matcha, the powdered leaf tea, upcoming announcements and more. |

  16. Nutrition Frontiers - Summer 2016 | Division of Cancer Prevention

    Science.gov (United States)

    Volume 7, Issue 3 The summer issue of Nutrition Frontiers showcases the combined effects of ursolic acid and resveratrol for skin cancer, the potential chemopreventive effects of the dietary supplement 4-MU, and a method to monitor a heterocyclic aromatic amine in dyed hair. Learn about our spotlight investigators, Drs. Michael Caligiuri and Jianhua Yu, and their research on dietary components for cancer prevention, upcoming announcements and more. |

  17. Nutrition Frontiers - Summer 2017 | Division of Cancer Prevention

    Science.gov (United States)

    Volume 8, Issue 3 Dear Colleague, The summer issue of Nutrition Frontiers showcases insulin-like growth factor and vitamin D in prostate cancer risk, bile acid and FXR inactivation and gender dissimilarity, and CerS6, a novel transcriptional target of p53 protein. Meet our spotlight investigator, Dr. Wendy Russell, and her research on the functional role of the gut microbiota. Learn about celery, the leafy stalk, upcoming announcements and more. |

  18. Frontier economy: the global perspectives of cryptocurrencies development

    OpenAIRE

    BOLDYRIKIN ALEXANDER A.

    2016-01-01

    In this article the author analyzes the perspectives of cryptocurrencies development in modern life and economy as a symbol of frontier economy and extremely new financial matter. A brief overview of electronic payments and virtual currency structure is given alongside with technical background. The emergence of electronic money and cryptocurrencies was an inevitable step in the evolution of Internet and electronic commerce. The author investigates the question how far cryptocurrencies might ...

  19. US Accelerator R&D Program Toward Intensity Frontier Machines

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, Vladimir [Fermilab

    2016-09-15

    The 2014 P5 report indicated the accelerator-based neutrino and rare decay physics research as a centerpiece of the US domestic HEP program. Operation, upgrade and development of the accelerators for the near-term and longer-term particle physics program at the Intensity Frontier face formidable challenges. Here we discuss key elements of the accelerator physics and technology R&D program toward future multi-MW proton accelerators.

  20. Discovering geothermal supercritical fluids: a new frontier for seismic exploration

    OpenAIRE

    Piana Agostinetti, Nicola; Licciardi, Andrea; Piccinini, Davide; Mazzarini, Francesco; Musumeci, Giovanni; Saccorotti, Gilberto; Chiarabba, Claudio

    2017-01-01

    Exploiting supercritical geothermal resources represents a frontier for the next generation of geothermal electrical power plant, as the heat capacity of supercritical fluids (SCF),which directly impacts on energy production, is much higher than that of fluids at subcritical conditions. Reconnaissance and location of intensively permeable and productive horizons at depth is the present limit for the development of SCF geothermal plants. We use, for the first time, teleseismic converted waves ...

  1. New insights into the stochastic ray production frontier

    DEFF Research Database (Denmark)

    Henningsen, Arne; Bělín, Matěj; Henningsen, Geraldine

    2017-01-01

    The stochastic ray production frontier was developed as an alternative to the traditional output distance function to model production processes with multiple inputs and multiple outputs. Its main advantage over the traditional approach is that it can be used when some output quantities of some...... important than the existing criticisms: taking logarithms of the polar coordinate angles, non-invariance to units of measurement, and ordering of the outputs. We also give some practical advice on how to address the newly raised issues....

  2. Evaluation of technical feasibility of closed-cycle non-equilibrium MHD power generation with direct coal firing

    Science.gov (United States)

    1981-11-01

    Program accomplishments in a continuing effort to demonstrate the feasibility of direct coal-fired, closed-cycle magnetohydrodynamic (MHD) power generation are reported. A user's manual for a two-dimensional MHD generator code and performance estimates for a nominal 30 MW argon segmented heater are given. The feedwater cooled Brayton cycle is discussed as well as the application of closed cycle MHD in an industrial cogeneration environment. Preliminary design for shell and tube primary heat exchanger and plant efficiency as a function of output power for open and closed cycle MHD power plants are also discussed.

  3. Old Borders and New Bordering Capabilities: Cities as Frontier Zones

    Directory of Open Access Journals (Sweden)

    Saskia Sassen

    2015-12-01

    Full Text Available The global city is a new frontier zone. Deregulation, privatization, and new fiscal and monetary policies create the formal instruments to construct their equivalent of the old military “fort”. The city is also a strategic frontier zone for those who lack power, and allows the making of informal politics. At the same time the border is a mix of regimes, marked by protections and opportunities for corporations and high-level professionals, and implies confinement, capture and detention for migrants. The essay discusses the transformation of the city in a frontier zone and analyses the separation between the capabilities entailed by territoriality and the geographic territory tout court. The analysis focuses on the effects of neoliberal policies that, far from making this a borderless world, have actually multiplied the bordered spaces that allow firms and markets to move across conventional borders. Cities are therefore one of the key sites where new neoliberal norms are made and where new identities emerge.

  4. Operational Experience with the Frontier System in CMS

    CERN Document Server

    Dykstra, David

    2012-01-01

    The Frontier framework is used in the CMS experiment at the LHC to deliver conditions data to processing clients worldwide, including calibration, alignment, and configuration information. Each of the central servers at CERN, called a Frontier Launchpad, uses tomcat as a servlet container to establish the communication between clients and the central Oracle database. HTTP-proxy squid servers, located close to clients, cache the responses to queries in order to provide high performance data access and to reduce the load on the central Oracle database. Each Frontier Launchpad also has its own reverse-proxy squid for caching. The three central servers have been delivering about 10 million responses every day since the LHC startup, containing about 60 GB data in total, to more than one hundred Squid servers located worldwide, with an average response time on the order of 10 milliseconds. The squid caches deployed worldwide process many more requests per day, over 700 million, and deliver over 40 TB of data. Sever...

  5. Statement of Problem of Pareto Frontier Management and Its Solution in the Analysis and Synthesis of Optimal Systems

    Directory of Open Access Journals (Sweden)

    I. K. Romanova

    2015-01-01

    mutually contradictory and it is possible to use them for description in the Pareto frontier terms. Techniques for the active influence on the Pareto frontier have allowed us to define parameters not only of the system regulators, but the control object itself, which permit changing the front position. The article analyses the impact of these parameters on the angles of the front, calculated, using the second derivative of the criterion, by the first dJ2/dJ1. It notes that derivatives may act as an assessment of the balance of compromises.The work reveals that for a General form model the change in natural frequency (time constant has inversely proportional impact on the tilt of Pareto frontier, i.e. the smaller the time constant, the steeper is front, i.e. it is possible to control the front tilt through changing the time constant. Thus, reducing the time constant leads to the left-hand shift of the Pareto frontier. As to the two-loop system, it shows that the increasing gain module of the angular velocity sensor causes compression of the Pareto frontier in overshoot and stretching time of the transition process. Here, a tilt of the Pareto frontier slightly changes. The increasing module of the sensor linear acceleration gain causes the left-hand shift of the Pareto frontier with simultaneously increasing angle of the front tilt, i.e. its sensitivity increases. The computations of the corresponding Pareto ranks showed that for two-loop system, each of the individual ranks corresponds to the variation of the coefficient of linear acceleration sensor at different gain values of the angular velocity sensor, and if the latter is modulo limited from below, it is necessary to move to the next Pareto rank. Found that the change of dynamic coefficient related to the efficiency of the elevator control has the greatest effect. Using the integral criteria gives the same effect. The influence of other factors on the Pareto frontier is insignificant for direct quality indicators. It

  6. Report on results of contract research. 'Research on MHD generation system'; MHD hatsuden system no kenkyu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1982-03-01

    'Research on MHD generation system' was implemented by its expert committee in the electric joint study group, with the results of fiscal 1981 reported. This year, technological reexamination was conducted for a 2,000 MWt commercial MHD generation plant, with evaluation carried out on the cost performance including the construction and operation cost. In addition, for the purpose of intermediate R and D towards the practicability, examination was also conducted on a system structure, concrete specifications of component element, cost of R and D including operation expenses for example, concerning an 100 MWt class experimental plant and a 500 MWt class plant. In the investigation of the overseas trend, information was summarized in detail on the experimental devices, combustors, generation channels, electrode materials, electrode phenomena, theoretical analyses, seeds, slag, component equipment, instrumental technologies, conceptual designs of generation plant, commercial plant, etc., in Soviet Union, China, Holland, India and EPRI, on the basis of the materials from the 19th MHD symposium held in UTSI and from the coal MHD specialist conference held in Sydney. (NEDO)

  7. MHD mode evolutions prior to minor and major disruptions in SST-1 plasma

    Energy Technology Data Exchange (ETDEWEB)

    Dhongde, Jasraj; Pradhan, Subrata, E-mail: pradhan@ipr.res.in; Bhandarkar, Manisha

    2017-01-15

    Highlights: • Observation of different regimes of MHD phenomena in SST-1 plasma. • MHD mode (m/n = 1/1, m/n = 2/1) evolutions prior to minor and major disruptions in SST-1 plasma. • MHD mode characteristics such as mode frequency, mode number, island width etc. in different regimes. - Abstract: Steady State Superconducting Tokamak (SST-1) is a medium size Tokamak (R{sub 0} = 1.1 m, a = 0.2 m, B{sub T} = 1.5T, Ip ∼ 110 kA) in operation at the Institute for Plasma Research, India. SST-1 uniquely experiments large aspect ratio (∼5.5) plasma in different operation regimes. In these experiments, repeatable characteristic MHD phenomena have been consistently observed. As the large aspect ratio plasma pulse progresses, these MHD phenomena display minor-major disruptions ably indicated in Mirnov oscillations, Mirnov oscillations with saw teeth and locked modes etc. Even though somewhat similar observations have been found in some other machines, these observations are found for the first time in large aspect ratio plasma of SST-1. This paper elaborates the magnetic field perturbations and mode evolutions due to MHD activities from Mirnov coils (poloidal and toroidal), Soft X-ray diagnostics, ECE diagnostics etc. This work further, for the first time reports quantitatively different regimes of MHD phenomena observed in SST-1 plasma, their details of mode evolutions characteristics as well as the subsequently observed minor, major disruptions supported with the physical explanations. This study will help developing disruption mitigation and avoidance scenarios for having better confinement plasma experiments.

  8. Diagnostic development and support of MHD test facilities. Final progress report, March 1980--March 1994

    Energy Technology Data Exchange (ETDEWEB)

    1995-02-01

    The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University (MSU), under U.S. Department of Energy (DOE) Contract No. DE-AC02-80ET-15601, Diagnostic Development and Support of MHD Test Facilities, developed diagnostic instruments for magnetohydrodynamic (MHD) power train data acquisition and for support of MHD component development test facilities. Microprocessor-controlled optical instruments, initially developed for Heat Recovery/Seed Recovery (HRSR) support, were refined, and new systems to measure temperatures and gas-seed-slag stream characteristics were developed. To further data acquisition and analysis capabilities, the diagnostic systems were interfaced with DIAL`s computers. Technical support was provided for the diagnostic needs of the national MHD research effort. DIAL personnel also cooperated with government agencies and private industries to improve the transformation of research and development results into processes, products and services applicable to their needs. The initial contract, Testing and Evaluation of Heat Recovery/Seed Recovery, established a data base on heat transfer, slagging effects on heat transfer surfaces, metal durability, secondary combustor performance, secondary combustor design requirements, and other information pertinent to the design of HR/SR components at the Coal-Fired Flow Facility (CFFF). To accomplish these objectives, a combustion test stand was constructed that simulated MHD environments, and mathematical models were developed and evaluated for the heat transfer in hot-wall test sections. Two transitions occurred during the span of this contract. In May 1983, the objectives and title of the contract changed from Testing and Evaluation of Heat Recovery/Seed Recovery to Diagnostic Development and Support of MHD Test Facilities. In July 1988, the research laboratory`s name changed from the MHD Energy Center to the Diagnostic Instrumentation and Analysis Laboratory.

  9. Transition from weak to strong cascade in MHD turbulence.

    Science.gov (United States)

    Verdini, Andrea; Grappin, Roland

    2012-07-13

    The transition from weak to strong turbulence when passing from large to small scales in magnetohydrodynamic (MHD) turbulence with guide field is a cornerstone of anisotropic turbulence theory. We present the first check of this transition, using the Shell-RMHD, which combines a shell model of perpendicular nonlinear coupling and linear propagation along the guide field. This model allows us to reach Reynolds numbers around 10(6). We obtain surprisingly good agreement with the theoretical predictions, with a reduced perpendicular energy spectrum scaling as k(⊥)(-2) at large scales and as k(⊥)(-5/3) at small scales, where critical balance between nonlinear and propagation time is reached. However, even in the strong regime, a high level of excitation is found in the weak coupling region of Fourier space, which is due to the rich frequency spectrum of large eddies. A corollary is that the reduced parallel spectral slope is not a definite test of the spectral anisotropy, contrary to standard belief.

  10. Extended MHD turbulence and its applications to the solar wind

    CERN Document Server

    Abdelhamid, Hamdi M; Mahajan, Swadesh M

    2016-01-01

    Extended MHD is a one-fluid model that incorporates two-fluid effects such as electron inertia and the Hall drift. This model is used to construct fully nonlinear Alfv\\'enic wave solutions, and thereby derive the kinetic and magnetic spectra by resorting to a Kolmogorov-like hypothesis based on the constant cascading rates of the energy and generalized helicities of this model. The magnetic and kinetic spectra are derived in the ideal $\\left(k 1/\\lambda_e\\right)$ regimes; $k$ is the wavenumber and $\\lambda_s = c/\\omega_{p s}$ is the skin depth of species `$s$'. In the Hall regime, it is shown that the emergent results are fully consistent with previous numerical and analytical studies, especially in the context of the solar wind. The focus is primarily on the electron inertia regime, where magnetic energy spectra with power-law indexes of $-11/3$ and $-13/3$ are always recovered. The latter, in particular, is quite close to recent observational evidence from the solar wind with a potential slope of approxima...

  11. MHD Modeling of Coronal Loops: the Transition Region Throat

    Science.gov (United States)

    Guarrasi, M.; Reale, F.; Orlando, S.; Mignone, A.; Klimchuk, J. A.

    2014-01-01

    Context. The expansion of coronal loops in the transition region may considerably influence the diagnostics of the plasma emission measure. The cross-sectional area of the loops is expected to depend on the temperature and pressure, and might be sensitive to the heating rate. Aims. The approach here is to study the area response to slow changes in the coronal heating rate, and check the current interpretation in terms of steady heating models. Methods. We study the area response with a time-dependent 2D magnetohydrodynamic (MHD) loop model, including the description of the expanding magnetic field, coronal heating and losses by thermal conduction, and radiation from optically thin plasma. We run a simulation for a loop 50 Mm long and quasi-statically heated to about 4 millikelvin. Results. We find that the area can change substantially with the quasi-steady heating rate, e.g., by approx. 40% at 0.5 millikelvin as the loop temperature varies between 1 millikelvin and 4 millikelvin, and, therefore, affects the interpretation of the differential emission measure vs. temperature (DEM(T)) curves.

  12. MHD biconvective flow of Powell Eyring nanofluid over stretched surface

    Science.gov (United States)

    Naseem, Faiza; Shafiq, Anum; Zhao, Lifeng; Naseem, Anum

    2017-06-01

    The present work is focused on behavioral characteristics of gyrotactic microorganisms to describe their role in heat and mass transfer in the presence of magnetohydrodynamic (MHD) forces in Powell-Eyring nanofluids. Implications concerning stretching sheet with respect to velocity, temperature, nanoparticle concentration and motile microorganism density were explored to highlight influential parameters. Aim of utilizing microorganisms was primarily to stabilize the nanoparticle suspension due to bioconvection generated by the combined effects of buoyancy forces and magnetic field. Influence of Newtonian heating was also analyzed by taking into account thermophoretic mechanism and Brownian motion effects to insinuate series solutions mediated by homotopy analysis method (HAM). Mathematical model captured the boundary layer regime that explicitly involved contemporary non linear partial differential equations converted into the ordinary differential equations. To depict nanofluid flow characteristics, pertinent parameters namely bioconvection Lewis number Lb, traditional Lewis number Le, bioconvection Péclet number Pe, buoyancy ratio parameter Nr, bioconvection Rayleigh number Rb, thermophoresis parameter Nt, Hartmann number M, Grashof number Gr, and Eckert number Ec were computed and analyzed. Results revealed evidence of hydromagnetic bioconvection for microorganism which was represented by graphs and tables. Our findings further show a significant effect of Newtonian heating over a stretching plate by examining the coefficient values of skin friction, local Nusselt number and the local density number. Comparison was made between Newtonian fluid and Powell-Eyring fluid on velocity field and temperature field. Results are compared of with contemporary studies and our findings are found in excellent agreement with these studies.

  13. MHD stability module for the National Transport Code Collaboration Library

    Science.gov (United States)

    Pletzer, A.; Manickam, J.; Jardin, S. C.; McCune, D.; Ludescher, Ch.; Klasky, S.; Randerson, L.

    1999-11-01

    There is a need to provide numerical tools to the fusion community that are robust, portable, easy to use, documented, and reviewed by independent peers. A web site (http://w3.pppl.gov/NTCC) where modules can be freely downloaded has been set up for that purpose [Status of the NTCC Modules Library (D McCune)]. The existence of such a library is in addition motivated by the increasing demand for programs that can be plugged into large packages with minimal effort. In particular, there has been some requests to make MHD stability codes such as the PEST, which are capable of simulating large scale plasma phenomena, available at the NTCC module library. Progress on the work to convert PEST to satisfy the NTCC module standards is presented. The resulting, new PEST interface is a collection of subroutines, which initialize, modify and extract data. Dynamic memory allocation is introduced to minimize memory requirements and allow for multiple runs. Embedded graphics routines are disabled and dependence on native binary files replaced by portable NetCDF files. To illustrate the flexibility of the module approach, numerical results obtained by integrating PEST-3, the mapping code DMAP and the equilibrium JSOLVER modules into a C++ and Java environment with remote database connectivity are presented.

  14. MHD modeling of coronal loops: the transition region throat

    Science.gov (United States)

    Guarrasi, M.; Reale, F.; Orlando, S.; Mignone, A.; Klimchuk, J. A.

    2014-04-01

    Context. The expansion of coronal loops in the transition region may considerably influence the diagnostics of the plasma emission measure. The cross-sectional area of the loops is expected to depend on the temperature and pressure, and might be sensitive to the heating rate. Aims: The approach here is to study the area response to slow changes in the coronal heating rate, and check the current interpretation in terms of steady heating models. Methods: We study the area response with a time-dependent 2D magnetohydrodynamic (MHD) loop model, including the description of the expanding magnetic field, coronal heating and losses by thermal conduction, and radiation from optically thin plasma. We run a simulation for a loop 50 Mm long and quasi-statically heated to about 4 MK. Results: We find that the area can change substantially with the quasi-steady heating rate, e.g., by ~40% at 0.5 MK as the loop temperature varies between 1 MK and 4 MK, and, therefore, affects the interpretation of the differential emission measure vs. temperature (DEM(T)) curves. The movie associated to Fig. 4 is available in electronic form at http://www.aanda.org

  15. New aspects of plasma sheet dynamics - MHD and kinetic theory

    Directory of Open Access Journals (Sweden)

    H. Wiechen

    1999-05-01

    Full Text Available Magnetic reconnection is a process of fundamental importance for the dynamics of the Earth's plasma sheet. In this context, the development of thin current sheets in the near-Earth plasma sheet is a topic of special interest because they could be a possible cause of microscopic fluctuations acting as collective non-idealness from a macroscopic point of view. Simulations of the near-Earth plasma sheet including boundary perturbations due to localized inflow through the northern (or southern plasma sheet boundary show developing thin current sheets in the near-Earth plasma sheet about 810 RE tailwards of the Earth. This location is largely independent from the localization of the perturbation. The second part of the paper deals with the problem of the macroscopic non-ideal consequences of microscopic fluctuations. A new model is presented that allows the quantitative calculation of macroscopic non-idealness without considering details of microscopic instabilities or turbulence. This model is only based on the assumption of a strongly fluctuating, mixing dynamics on microscopic scales in phase space. The result of this approach is an expression for anomalous non-idealness formally similar to the Krook resistivity but now describing the macroscopic consequences of collective microscopic fluctuations, not of collisions.Key words. Magnetospheric physics (plasma sheet · Space plasma physics (kinetic and MHD theory; magnetic reconnection

  16. Review of free-surface MHD experiments and modeling.

    Energy Technology Data Exchange (ETDEWEB)

    Molokov, S.; Reed, C. B.

    2000-06-02

    This review paper was prepared to survey the present status of analytical and experimental work in the area of free surface MHD and thus provide a well informed starting point for further work by the Advanced Limiter-diverter Plasma-facing Systems (ALPS) program. ALPS were initiated to evaluate the potential for improved performance and lifetime for plasma-facing systems. The main goal of the program is to demonstrate the advantages of advanced limiter/diverter systems over conventional systems in terms of power density capability, component lifetime, and power conversion efficiency, while providing for safe operation and minimizing impurity concerns for the plasma. Most of the work to date has been applied to free surface liquids. A multi-disciplinary team from several institutions has been organized to address the key issues associated with these systems. The main performance goals for advanced limiters and diverters are a peak heat flux of >50 MW/m{sup 2}, elimination of a lifetime limit for erosion, and the ability to extract useful heat at high power conversion efficiency ({approximately}40%). The evaluation of various options is being conducted through a combination of laboratory experiments, modeling of key processes, and conceptual design studies.

  17. Ionospheric conductance distribution and MHD wave structure: observation and model

    Directory of Open Access Journals (Sweden)

    F. Budnik

    Full Text Available The ionosphere influences magnetohydrodynamic waves in the magnetosphere by damping because of Joule heating and by varying the wave structure itself. There are different eigenvalues and eigensolutions of the three dimensional toroidal wave equation if the height integrated Pedersen conductivity exceeds a critical value, namely the wave conductance of the magnetosphere. As a result a jump in frequency can be observed in ULF pulsation records. This effect mainly occurs in regions with gradients in the Pedersen conductances, as in the auroral oval or the dawn and dusk areas. A pulsation event recorded by the geostationary GOES-6 satellite is presented. We explain the observed change in frequency as a change in the wave structure while crossing the terminator. Furthermore, selected results of numerical simulations in a dipole magnetosphere with realistic ionospheric conditions are discussed. These are in good agreement with the observational data.

    Key words. Ionosphere · (Ionosphere · magnetosphere interactions · Magnetospheric physics · Magnetosphere · ionosphere interactions · MHD waves and instabilities.

  18. Ionospheric conductance distribution and MHD wave structure: observation and model

    Directory of Open Access Journals (Sweden)

    F. Budnik

    1998-02-01

    Full Text Available The ionosphere influences magnetohydrodynamic waves in the magnetosphere by damping because of Joule heating and by varying the wave structure itself. There are different eigenvalues and eigensolutions of the three dimensional toroidal wave equation if the height integrated Pedersen conductivity exceeds a critical value, namely the wave conductance of the magnetosphere. As a result a jump in frequency can be observed in ULF pulsation records. This effect mainly occurs in regions with gradients in the Pedersen conductances, as in the auroral oval or the dawn and dusk areas. A pulsation event recorded by the geostationary GOES-6 satellite is presented. We explain the observed change in frequency as a change in the wave structure while crossing the terminator. Furthermore, selected results of numerical simulations in a dipole magnetosphere with realistic ionospheric conditions are discussed. These are in good agreement with the observational data.Key words. Ionosphere · (Ionosphere · magnetosphere interactions · Magnetospheric physics · Magnetosphere · ionosphere interactions · MHD waves and instabilities.

  19. Resistive MHD Stability Studies of Reversed-Field Pinch

    Energy Technology Data Exchange (ETDEWEB)

    Liu, D.H.

    1996-11-01

    Resistive MHD stability studies of RFPs for various {mu} profiles and pressure profiles have been made. For the first time, a system which can simulate both the experimental hollow {mu} profiles and the locally flattened {mu} profiles has ben set up, thus enabling the extensive stability studies of equilibrium profiles. A {mu} profile locally flattened around the reversal surface is found to deteriorate the internal mode and the m=0 mode. It also expands the corresponding spectra of unstable modes. These may be associated with the increasing magnetic fluctuations. Broadening the {mu} profile is beneficial to stabilizing the internal modes. When a {mu} profile is hollow near the magnetic surface, the spectrum shrinks to low k{sub z} values and the field-reversal is deepened. Whether this hollow {mu} profile deteriorates RFP stability depends on its depth of hollowness and the pinch parameter. Furthermore, unstable modes in RFP are found to be very sensitive to the pressure gradient at the rational surface. Even for the typical {beta}{sub p}=0.1 case, the shaping of the pressure profile dramatically changes the stability of both the plasma core and the plasma boundary regions. These may cast doubt on the `free-force` assumption which is widely used in RFP simulations. 23 refs.

  20. Computer controlled MHD power consolidation and pulse generation system

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R.; Marcotte, K.; Donnelly, M.

    1990-01-01

    The major goal of this research project is to establish the feasibility of a power conversion technology which will permit the direct synthesis of computer programmable pulse power. Feasibility has been established in this project by demonstration of direct synthesis of commercial frequency power by means of computer control. The power input to the conversion system is assumed to be a Faraday connected MHD generator which may be viewed as a multi-terminal dc source and is simulated for the purpose of this demonstration by a set of dc power supplies. This consolidation/inversion (CI), process will be referred to subsequently as Pulse Amplitude Synthesis and Control (PASC). A secondary goal is to deliver a controller subsystem consisting of a computer, software, and computer interface board which can serve as one of the building blocks for a possible phase II prototype system. This report period work summarizes the accomplishments and covers the high points of the two year project. 6 refs., 41 figs.

  1. MHD simulation study of compact toroid injection into magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Yoshio; Kishimoto, Yasuaki [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Hayashi, Takaya [National Inst. for Fusion Science, Toki, Gifu (Japan)

    2000-06-01

    To understand the fuelling process in a fusion device by a compact toroid (CT) plasmoid injection method, we have carried out MHD numerical simulations where a spheromak-like CT (SCT) is injected into a magnetized target plasma region. So far, we revealed that the penetration depth of the SCT plasma becomes shorter than that estimated from the conducting sphere (CS) model, because in the simulation the Lorentz force of the target magnetic field sequentially decelerates the injected SCT while in the CS model only the magnetic pressure force acts as the deceleration mechanism. In this study, we represent the new theoretical model where the injected SCT is decelerated by both the magnetic pressure force and the magnetic tension force (we call it the non-slipping sphere (NS) model) and investigate in detail the deceleration mechanism of the SCT by comparison with simulation results. As a result, it is found that the decrease of the SCT kinetic energy in the simulation coincides with that in the NS model more than in the CS model. It means that not only the magnetic pressure force but also the magnetic tension force acts as the deceleration mechanism of the SCT. Furthermore, it is revealed that magnetic reconnection between the SCT magnetic field and the target magnetic field plays a role to relax the SCT deceleration. (author)

  2. Frontier in hair loss and trichoscopy: A review

    Directory of Open Access Journals (Sweden)

    Ebtisam Elghblawi

    2016-07-01

    Full Text Available Skin surfaces have always been examined using dermoscopy, a familiar tool which is useful to magnify and examine skin especially in cases of pigmented skin lesions. However, to examine the hair and scalp, a practical tool called trichoscopy has surfaced recently and has proven to be handy and functional in diagnosing most hair-related diseases. It is also referred to as dermoscopy of the hair and the scalp. It can aid in assessing active diseases in the scalp and hair, such as yellow dots, dystrophic hairs, cadaverized black dots, white dots, and exclamation mark hairs – all of which denote specific criteria for hair diseases. Trichoscopy is a very newly developed non-invasive technique for hair image analysis. It permits non-invasive visualization of hair shafts at higher intensification (about ×70 and ×100 and enables measurement of hair shaft width without the need for removing hair for diagnostic reasons. Moreover, it helps in vivo visualization of the epidermal portion of hair follicles and perifollicular epidermis (orifices. Consequently, it is valuable as it permits the inspection of structures that are otherwise not seen by the naked eye. Trichoscopy is the new frontier for the diagnosis of hair and scalp disease. Nowadays, a trichoscope is considered a must for dermatologists and it is a hot topic in the treatment of hair diseases. There is pooled evidence that the utilization of trichoscopy in the clinical setting for evaluating hair disorders can improve its diagnostic capability beyond simple clinical scrutiny. Trichoscopy can identify both hair shaft and hair opening abnormalities without the need for hair sampling, as well as distinguish between different scalp and hair diseases. Furthermore, it can give easy and quick evaluation of the hair with a follow-up to determine progress and prognosis of the disease with photos. It can also aid in some genetic hair shaft dystrophies such as trichorrhexis nodosa, trichorrhexis

  3. Europe's Southern Frontier: Evolving Trends toward What?

    Science.gov (United States)

    Linz, Juan

    1979-01-01

    Analyzes northern Mediterranean politics in light of demographic, economic, and social characteristics of Italy, Spain, Portugal, and Greece. Identifies ambivalence as the characteristic attitude relating to present and future politics, the economy, and the area's international position. (DB)

  4. Security in the CernVM File System and the Frontier Distributed Database Caching System

    CERN Document Server

    Dykstra, David

    2014-01-01

    Both the CernVM File System (CVMFS) and the Frontier Distributed Database Caching System (Frontier) distribute centrally updated data worldwide for LHC experiments using http proxy caches. Neither system provides privacy or access control on reading the data, but both control access to updates of the data and can guarantee the integrity of the data transferred to clients over the internet. CVMFS has since its early days required digital signatures and secure hashes on all distributed data, and recently both CVMFS and Frontier have added X509-based integrity checking. In this paper we detail and compare the security models of CVMFS and Frontier.

  5. An MHD Study of the Interaction Between the Solar Wind and the Interstellar Medium

    Science.gov (United States)

    Steinolfson, R. S.

    1996-01-01

    The overall objective of this research program is to obtain a better understanding of the interaction between the solar wind and the interstellar medium through the use of numerical solutions of the time-dependent magnetohydrodynamic (MHD) equations. The simulated results have been compared with observations where possible and with the results from previous analytic and numerical studies. The primary accomplishment of this project has been the development of codes for 2-D models in both spherical and cylindrical coordinates and the application of the codes to the solar wind/interstellar medium interaction. Computations have been carried out for both a relatively simple gas-dynamic interaction and a flow-aligned interstellar magnetic field. The results have been shown to compare favorably with models that use more approximations and to modify and extend the previous results as would be expected. The simulations have also been used along with a data analysis study to provide a quantitative estimate of the distance to the termination and bow shocks. Some of the specific topics that have been studied are: (1) gas dynamic models of the solar wind/interstellar medium interaction, (2) termination shock response to large-scale solar wind fluctuations, and (3) distances to the termination shock and heliopause. The main results from each of these studies are summarized. The results were published in three papers which are included as attachments.

  6. MHD Integrated Topping Cycle Project. Fourteenth quarterly technical progress report, November 1, 1990-- January 31, 1991

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-01

    This fourteenth quarterly technical progress report of the MHD Integrated Topping Cycle Project presents the accomplishments during the period November 1, 1990 to January 31, 1991. Testing of the High Pressure Cooling Subsystem electrical isolator was completed. The PEEK material successfully passed the high temperature, high pressure duration tests (50 hours). The Combustion Subsystem drawings were CADAM released. The procurement process is in progress. An equipment specification and RFP were prepared for the new Low Pressure Cooling System (LPCS) and released for quotation. Work has been conducted on confirmation tests leading to final gas-side designs and studies to assist in channel fabrication.The final cathode gas-side design and the proposed gas-side designs of the anode and sidewall are presented. Anode confirmation tests and related analyses of anode wear mechanisms used in the selection of the proposed anode design are presented. Sidewall confirmation tests, which were used to select the proposed gas-side design, were conducted. The design for the full scale CDIF system was completed. A test program was initiated to investigate the practicality of using Avco current controls for current consolidation in the power takeoff (PTO) regions and to determine the cause of past current consolidation failures. Another important activity was the installation of 1A4-style coupons in the 1A1 channel. A description of the coupons and their location with 1A1 channel is presented herein.

  7. The ideal tearing mode: 2D MHD simulations in the linear and nonlinear regimes

    Science.gov (United States)

    Landi, Simone; Del Zanna, Luca; Pucci, Fulvia; Velli, Marco; Papini, Emanuele

    2015-04-01

    We present compressible, resistive MHD numerical simulations of the linear and nonlinear evolution of the tearing instability, for both Harris sheet and force-free initial equilibrium configurations. We analyze the behavior of a current sheet with aspect ratio S1/3, where S is the Lundquist number. This scaling has been recently recognized to be the threshold for fast reconnection occurring on the ideal Alfvenic timescale, with a maximum growth rate that becomes asymptotically independent on S. Our simulations clearly confirm that the tearing instability maximum growth rate and the full dispersion relation are exactly those predicted by the linear theory, at least for the values of S explored here. In the nonlinear stage, we notice the rapid onset and subsequent coalescence of plasmoids, as observed in previous simulations of the Sweet-Parker reconnection scenario. These findings strongly support the idea that in a fully dynamic regime, as soon as current sheets develop and reach the critical threshold in their aspect ratio of S1/3 (occurring well before the Sweet-Parker configuration is able to form), the tearing mode is able to trigger fast reconnection and plasmoids formation on Alfvenic timescales, as required to explain the violent flare activity often observed in solar and astrophysical plasmas.

  8. 3D Resistive MHD Simulations of Formation, Compression, and Acceleration of Compact Tori

    Science.gov (United States)

    Woodruff, Simon; Meyer, Thomas; Stuber, James; Romero-Talamas, Carlos; Brown, Michael; Kaur, Manjit; Schaffner, David

    2017-10-01

    We present results from extended resistive 3D MHD simulations (NIMROD) pertaining to a new formation method for toroidal plasmas using a reconnection region that forms in a radial implosion, and results from the acceleration of CTs along a drift tube that are accelerated by a coil and are allowed to go tilt unstable and form a helical minimum energy state. The new formation method results from a reconnection region that is generated between two magnetic compression coils that are ramped to 320kV in 2 μs. When the compressing field is aligned anti-parallel to a pre-existing CT, a current sheet and reconnection region forms that accelerates plasma radially inwards up to 500km/s which stagnates and directed energy converts to thermal, raising temperatures to 500eV. When field is aligned parallel to the pre-existing CT, the configuration can be accelerated along a drift tube. For certain ratios of magnetic field to density, the CT goes tilt-unstable forming a twisted flux rope, which can also be accelerated and stagnated on an end wall, where temperature and field increases as the plasma compresses. We compare simulation results with adiabatic scaling relations. Work supported by ARPA-E ALPHA program and DARPA.

  9. Relativistic MHD modeling of magnetized neutron stars, pulsar winds, and their nebulae

    Science.gov (United States)

    Del Zanna, L.; Pili, A. G.; Olmi, B.; Bucciantini, N.; Amato, E.

    2018-01-01

    Neutron stars are among the most fascinating astrophysical sources, being characterized by strong gravity, densities about the nuclear one or even above, and huge magnetic fields. Their observational signatures can be extremely diverse across the electromagnetic spectrum, ranging from the periodic and low-frequency signals of radio pulsars, up to the abrupt high-energy gamma-ray flares of magnetars, where energies of ∼ {10}46 {erg} are released in a few seconds. Fast-rotating and highly magnetized neutron stars are expected to launch powerful relativistic winds, whose interaction with the supernova remnants gives rise to the non-thermal emission of pulsar wind nebulae, which are known cosmic accelerators of electrons and positrons up to PeV energies. In the extreme cases of proto-magnetars (magnetic fields of ∼ {10}15 G and millisecond periods), a similar mechanism is likely to provide a viable engine for the still mysterious gamma-ray bursts. The key ingredient in all these spectacular manifestations of neutron stars is the presence of strong magnetic fields in their constituent plasma. Here we will present recent updates of a couple of state-of-the-art numerical investigations by the high-energy astrophysics group in Arcetri: a comprehensive modeling of the steady-state axisymmetric structure of rotating magnetized neutron stars in general relativity, and dynamical 3D MHD simulations of relativistic pulsar winds and their associated nebulae.

  10. Evaluation of MHD materials for use in high-temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Guidotti, R.

    1978-06-15

    The MHD and high-temperature fuel cell literature was surveyed for data pertaining to materials properties in order to identify materials used in MHD power generation which also might be suitable for component use in high-temperature fuel cells. Classes of MHD-electrode materials evaluated include carbides, nitrides, silicides, borides, composites, and oxides. Y/sub 2/O/sub 3/-stabilized ZrO/sub 2/ used as a reference point to evaluate materials for use in the solid-oxide fuel cell. Physical and chemical properties such as electrical resistivity, coefficient of thermal expansion, and thermodynamic stability toward oxidation were used to screen candidate materials. A number of the non-oxide ceramic MHD-electrode materials appear promising for use in the solid-electrolyte and molten-carbonate fuel cell as anodes or anode constituents. The MHD-insulator materials appear suitable candidates for electrolyte-support tiles in the molten-carbonate fuel cells. The merits and possible problem areas for these applications are discussed and additional needed areas of research are delineated.

  11. Simulation of two-dimensional fully developed laminar flow for a magneto-hydrodynamic (MHD) pump.

    Science.gov (United States)

    Wang, Pei-Jen; Chang, Chia-Yuan; Chang, Ming-Lang

    2004-07-30

    MHD micro-pumps circumvent the wear and fatigue caused by high pressure-drop across the check valves of mechanical micro-pumps in micro-fluidic systems. Early analyses of the fluid flow for MHD micro-pumps were mostly made possible by the Poiseuille flow theory; however, this conventional laminar approach cannot illustrate the effects of various channel sizes and shapes. This paper, therefore, presents a simplified MHD flow model based upon steady state, incompressible and fully developed laminar flow theory to investigate the characteristics of a MHD pump. Inside the pump, flowing along the channel is the electrically conducting fluid flowing driven by the Lorentz forces in the direction perpendicular to both dc magnetic field and applied electric currents. The Lorentz forces were converted into a hydrostatic pressure gradient in the momentum equations of the MHD channel flow model. The numerical simulations conducted with the explicit finite difference method show that the channel dimensions and the induced Lorentz forces have significant influences on the flow velocity profile. Furthermore, the simulation results agree well with the experimental results published by other researchers.

  12. A simplified MHD model of capillary Z-Pinch compared with experiments

    Energy Technology Data Exchange (ETDEWEB)

    Shapolov, A.A.; Kiss, M.; Kukhlevsky, S.V. [Institute of Physics, University of Pecs (Hungary)

    2016-11-15

    The most accurate models of the capillary Z-pinches used for excitation of soft X-ray lasers and photolithography XUV sources currently are based on the magnetohydrodynamics theory (MHD). The output of MHD-based models greatly depends on details in the mathematical description, such as initial and boundary conditions, approximations of plasma parameters, etc. Small experimental groups who develop soft X-ray/XUV sources often use the simplest Z-pinch models for analysis of their experimental results, despite of these models are inconsistent with the MHD equations. In the present study, keeping only the essential terms in the MHD equations, we obtained a simplified MHD model of cylindrically symmetric capillary Z-pinch. The model gives accurate results compared to experiments with argon plasmas, and provides simple analysis of temporal evolution of main plasma parameters. The results clarify the influence of viscosity, heat flux and approximations of plasma conductivity on the dynamics of capillary Z-pinch plasmas. The model can be useful for researchers, especially experimentalists, who develop the soft X-ray/XUV sources. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Estimating a planetary magnetic field with time-dependent global MHD simulations using an adjoint approach

    Science.gov (United States)

    Nabert, Christian; Othmer, Carsten; Glassmeier, Karl-Heinz

    2017-05-01

    The interaction of the solar wind with a planetary magnetic field causes electrical currents that modify the magnetic field distribution around the planet. We present an approach to estimating the planetary magnetic field from in situ spacecraft data using a magnetohydrodynamic (MHD) simulation approach. The method is developed with respect to the upcoming BepiColombo mission to planet Mercury aimed at determining the planet's magnetic field and its interior electrical conductivity distribution. In contrast to the widely used empirical models, global MHD simulations allow the calculation of the strongly time-dependent interaction process of the solar wind with the planet. As a first approach, we use a simple MHD simulation code that includes time-dependent solar wind and magnetic field parameters. The planetary parameters are estimated by minimizing the misfit of spacecraft data and simulation results with a gradient-based optimization. As the calculation of gradients with respect to many parameters is usually very time-consuming, we investigate the application of an adjoint MHD model. This adjoint MHD model is generated by an automatic differentiation tool to compute the gradients efficiently. The computational cost for determining the gradient with an adjoint approach is nearly independent of the number of parameters. Our method is validated by application to THEMIS (Time History of Events and Macroscale Interactions during Substorms) magnetosheath data to estimate Earth's dipole moment.

  14. MHD Integrated Topping Cycle Project. Sixteenth quarterly technical progress report, May 1991--July 1991

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    The Magnetohydrodynamics (MHD) Integrated Topping Cycle (ITC) Project represents the culmination of the proof-of-concept (POC) development stage in the US Department of Energy (DOE) program to advance MHD technology to early commercial development stage utility power applications. The project is a joint effort, combining the skills of three topping cycle component developers: TRW, Avco/TDS, and Westinghouse. TRW, the prime contractor and system integrator, is responsible for the 50 thermal megawatt (50 MW{sub t}) slagging coal combustion subsystem. Avco/TDS is responsible for the MHD channel subsystem (nozzle, channel, diffuser, and power conditioning circuits), and Westinghouse is responsible for the current consolidation subsystem. The ITC Project will advance the state-of-the-art in MHD power systems with the design, construction, and integrated testing of 50 MW{sub t} power train components which are prototypical of the equipment that will be used in an early commercial scale MHD utility retrofit. Long duration testing of the integrated power train at the Component Development and Integration Facility (CDIF) in Butte, Montana will be performed, so that by the early 1990`s, an engineering data base on the reliability, availability, maintainability and performance of the system will be available to allow scaleup of the prototypical designs to the next development level. This Sixteenth Quarterly Technical Progress Report covers the period May 1, 1991 to July 31, 1991.

  15. MHD activity in the ISX-B tokamak: experimental results and theoretical interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Carreras, B.A.; Dunlap, J.L.; Bell, J.D.; Charlton, L.A.; Cooper, W.A.; Dory, R.A.; Hender, T.C.; Hicks, H.R.; Holmes, J.A.; Lynch, V.E.

    1982-01-01

    The observed spectrum of MHD fluctuations in the ISX-B tokamak is clearly dominated by the n=1 mode when the q=1 surface is in the plasma. This fact agrees well with theoretical predictions based on 3-D resistive MHD calculations. They show that the (m=1; n=1) mode is then the dominant instability. It drives other n=1 modes through toroidal coupling and n>1 modes through nonlinear couplings. These theoretically predicted mode structures have been compared in detail with the experimentally measured wave forms (using arrays of soft x-ray detectors). The agreement is excellent. More detailed comparisons between theory and experiment have required careful reconstructions of the ISX-B equilibria. The equilibria so constructed have permitted a precise evaluation of the ideal MHD stability properties of ISX-B. The present results indicate that the high ..beta.. ISX-B equilibria are marginally stable to finite eta ideal MHD modes. The resistive MHD calculations also show that at finite ..beta.. there are unstable resistive pressure driven modes.

  16. The effects of weakly 3-D equilibrium on MHD stabiliyt of tokamak pedestals

    Science.gov (United States)

    Hegna, C. C.

    2013-10-01

    The stability of MHD modes is evaluated in the presence of an equilibrium perturbed by a topology-preserving 3-D distortion. The theory employs a perturbation approach assuming that the 3-D amplitude is small. In general, the 3-D distortion is destabilizing as it lowers the critical conditions for instability for the least stable mode. The theory is specialized to the MHD stability of pedestal modes in the presence of shielded RMP fields. Previous work has demonstrated that local MHD stability properties (and hence microinstabilities) can be significantly altered by the presence of applied 3-D fields. In this work, we expand these calculations in an effort to address whether RMP fields can affect `global' peeling-ballooning modes. For this application, the dominant 3-D modification is due to the localized resonant current responses at rational surfaces. These localized currents couple harmonics with different toroidal numbers and produce an MHD eigenmode with multiple toroidal harmonics. The physics of how the localized current structures affect the MHD stability of tokamak pedestals will be discussed. Research Supported by U. S. DoE grant no. DE-FG02-86ER53218.

  17. The Next Frontier in Industiral Energy Efficiency

    NARCIS (Netherlands)

    Worrell, E.

    2010-01-01

    Industry contributes directly and indirectly (through consumed electricity) about 37% of the global greenhouse gas emissions, of which over 80% is from energy use. Total energy-related emissions, which were 9.9 GtCO2 in 2004, have grown by 65% since 1971. In the near future, energy efficiency is

  18. Educational Journeys on the Web Frontier.

    Science.gov (United States)

    Shneiderman, Ben

    1998-01-01

    Presents a guiding framework (Relate-Create-Donate) for integrating World Wide Web technology into higher education and describes two specific strategies: "Encyclopedia Of" and "Open Projects." The Encyclopedia of Virtual Environments (EVE), Online Library of Information Visualization Environments (OLIVE), and Student HCI Online Research…

  19. Observations from the frontier of deliciousness

    DEFF Research Database (Denmark)

    Evans, Joshua David

    2014-01-01

    This pursuit of insect-related gastronomic knowledge and how to apply it in the kitchen has taught me also about cooking in general. Cooking can expand the edible world through the discovery and application of deliciousness, further diversifying the range of foods available to us. It can also...

  20. Exciton Polaritons in Microcavities New Frontiers

    CERN Document Server

    Sanvitto, Daniele

    2012-01-01

    In the past decade, there has been a burst of new and fascinating physics associated to the unique properties of two-dimensional exciton polaritons, their recent demonstration of condensation under non-equilibrium conditions and all the related quantum phenomena, which have stimulated extensive research work. This monograph summarizes the current state of the art of research on exciton polaritons in microcavities: their interactions, fast dynamics, spin-dependent phenomena, temporal and spatial coherence, condensation under non-equilibrium conditions, related collective quantum phenomena and most advanced applications. The monograph is written by the most active authors who have strongly contributed to the advances in this area. It is of great interests to both physicists approaching this subject for the first time, as well as a wide audience of experts in other disciplines who want to be updated on this fast moving field.

  1. Frontier Security: The Case of Brazil

    Science.gov (United States)

    2016-08-01

    Hemisphere defense and security affairs, U.S. policy for Latin America and the Caribbean, civil-military relations, and defense education. Before... geography precludes extensive physical barriers. The country has found that law Figure 1. Brazil’s Defense Budget and GDP Growth Year 0 5,000 10,000...and had a history reaching back to the smug- gling of rubber out of South America from the late 19th century until World War II. Law enforce- ment

  2. MHD Effects of a Ferritic Wall on Tokamak Plasmas

    Science.gov (United States)

    Hughes, Paul E.

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

  3. Fundamental Studies On Development Of MHD (Magnetohydrodynamic) Generator Implement On Wave Energy Harvesting

    Science.gov (United States)

    Majid, M. F. M. A.; Apandi, Muhamad Al-Hakim Md; Sabri, M.; Shahril, K.

    2016-02-01

    As increasing of agricultural and industrial activities each year has led to an increasing in demand for energy. Possibility in the future, the country was not able to offer a lot of energy and power demand. This means that we need to focus on renewable energy to supply the demand for energy. Energy harvesting is among a method that can contribute on the renewable energy. MHD power generator is a new way to harvest the energy especially Ocean wave energy. An experimental investigation was conducted to explore performance of MHD generator. The effect of intensity of NaCl Solution (Sea Water), flow rate of NaCl solution, magnetic strength and magnet position to the current produce was analyzed. The result shows that each factor is give a significant effect to the current produce, because of that each factor need to consider on develop of MHD generator to harvest the wave energy as an alternative way to support the demand for energy.

  4. Ideal MHD Stability Prediction and Required Power for EAST Advanced Scenario

    Science.gov (United States)

    Chen, Junjie; Li, Guoqiang; Qian, Jinping; Liu, Zixi

    2012-11-01

    The Experimental Advanced Superconducting Tokamak (EAST) is the first fully superconducting tokamak with a D-shaped cross-sectional plasma presently in operation. The ideal magnetohydrodynamic (MHD) stability and required power for the EAST advanced tokamak (AT) scenario with negative central shear and double transport barrier (DTB) are investigated. With the equilibrium code TOQ and stability code GATO, the ideal MHD stability is analyzed. It is shown that a moderate ratio of edge transport barriers' (ETB) height to internal transport barriers' (ITBs) height is beneficial to ideal MHD stability. The normalized beta βN limit is about 2.20 (without wall) and 3.70 (with ideal wall). With the scaling law of energy confinement time, the required heating power for EAST AT scenario is calculated. The total heating power Pt increases as the toroidal magnetic field BT or the normalized beta βN is increased.

  5. MHD mode activity and the velocity shear layer at TJ-II

    Science.gov (United States)

    van Milligen, B. Ph.; García, L.; Carreras, B. A.; Pedrosa, M. A.; Hidalgo, C.; Alonso, J. A.; Estrada, T.; Ascasíbar, E.

    2012-01-01

    Low-frequency MHD mode activity was studied at the TJ-II stellarator. A spatiotemporal Fourier technique was used to resolve frequency-degenerate modes. By means of this technique, several MHD modes could be identified in discharges with a spontaneous confinement transition in different but similar magnetic configurations. The configurations differed mainly with respect to the radial position of the rational surfaces, thus allowing the reconstruction of a poloidal mode rotation profile based on the mode activity, which was found to be consistent with earlier work. The detected mode spectrum also provided an explanation for the bicoherence observed in one of the configurations after the confinement transition. Both the mode spectrum and the velocity profile were closely reproduced by nonlinear resistive MHD calculations in simplified geometry. As a consequence, the magnetic Reynolds stress is hypothesized to play an important role in the establishment of the velocity shear layer in TJ-II and the concomitant confinement transition.

  6. Ideal MHD(-Einstein) Solutions Obeying The Force-Free Condition

    CERN Document Server

    Chu, Yi-Zen

    2016-01-01

    We find two families of analytic solutions to the ideal magnetohydrodynamics (iMHD) equations, in a class of 4-dimensional (4D) curved spacetimes. The plasma current is null, and as a result, the stress-energy tensor of the plasma itself can be chosen to take a cosmological-constant-like form. Despite the presence of a plasma, the force-free condition - where the electromagnetic current is orthogonal to the Maxwell tensor - continues to be maintained. Moreover, a special case of one of these two families leads us to a fully self-consistent solution to the Einstein-iMHD equations: we obtain the Vaidya-(anti-)de Sitter metric sourced by the plasma and a null electromagnetic stress tensor. We also provide a Mathematica code that researchers may use to readily verify analytic solutions to these iMHD equations in any curved 4D geometry.

  7. Newtonian CAFE: a new ideal MHD code to study the solar atmosphere

    Science.gov (United States)

    González, J. J.; Guzmán, F.

    2015-12-01

    In this work we present a new independent code designed to solve the equations of classical ideal magnetohydrodynamics (MHD) in three dimensions, submitted to a constant gravitational field. The purpose of the code centers on the analysis of solar phenomena within the photosphere-corona region. In special the code is capable to simulate the propagation of impulsively generated linear and non-linear MHD waves in the non-isothermal solar atmosphere. We present 1D and 2D standard tests to demonstrate the quality of the numerical results obtained with our code. As 3D tests we present the propagation of MHD-gravity waves and vortices in the solar atmosphere. The code is based on high-resolution shock-capturing methods, uses the HLLE flux formula combined with Minmod, MC and WENO5 reconstructors. The divergence free magnetic field constraint is controlled using the Flux Constrained Transport method.

  8. The Effect of Magnetohydrodynamic (MHD) Energy Bypass on Specific Thrust for a Supersonic Turbojet Engine

    Science.gov (United States)

    Benyo, Theresa L.

    2010-01-01

    This paper describes the preliminary results of a thermodynamic cycle analysis of a supersonic turbojet engine with a magnetohydrodynamic (MHD) energy bypass system that explores a wide range of MHD enthalpy extraction parameters. Through the analysis described here, it is shown that applying a magnetic field to a flow path in the Mach 2.0 to 3.5 range can increase the specific thrust of the turbojet engine up to as much as 420 N/(kg/s) provided that the magnitude of the magnetic field is in the range of 1 to 5 Tesla. The MHD energy bypass can also increase the operating Mach number range for a supersonic turbojet engine into the hypersonic flight regime. In this case, the Mach number range is shown to be extended to Mach 7.0.

  9. Feasibility analysis of two-phase MHD energy conversion for liquid metal cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Wu Qiao [Department of Nuclear Engineering and Radiation Health Physics, Oregon State University, Corvallis, OR 97331 (United States)], E-mail: qiao@engr.orst.edu; Schubring, DuWayne L. [Department of Nuclear Engineering and Radiation Health Physics, Oregon State University, Corvallis, OR 97331 (United States); Sienicki, James J. [Reactor Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2007-11-15

    A two-phase MHD energy conversion unit is proposed to a liquid metal cooled fast reactor. Using supercritical CO{sub 2} as the working fluid in the gas cycle without considering friction and heat losses, the optimized cycles efficiency is obtained, which is about 5% higher than that of the gas turbine Brayton cycle with the same regenerator/compressor configurations. Based on a simple MHD power analysis and the two-phase homogeneous flow model, the important system operational conditions were estimated. The results suggest that a liquid lead pump of at least 20% of the MHD power output is needed in order to convert the 400 MW reactor heat into electricity at the specified thermal efficiency, unless a mixture foam flow of void fraction greater than 80% is achievable at very high mixture velocity.

  10. Non-linear interaction between high energy ions and MHD-modes

    Energy Technology Data Exchange (ETDEWEB)

    Bergkvist, Tommy

    2001-12-01

    When heating a fusion plasma with ICRE or NBI a non-Maxwellian distribution function with high energy ions is created. Ions which are in resonance with a MHD mode will interact with the electric field from the mode and in some circumstances energy will flow from the particles to the mode or opposite. A quasi-linear model for the interaction between high energy ions and a MHD mode has been developed. To solve the time evolution of the MHD mode a module has been implemented into the Monte Carlo code FIDO, which is used for calculating a 3-dimensional distribution function. The model has been tested for an internal kink mode during fishbone oscillations.

  11. Comparison of three MHD flow control methods for self-cooled liquid metal blankets

    Energy Technology Data Exchange (ETDEWEB)

    Walker, J.S.; Picologlou, B.F.

    1986-01-01

    The heat deposition in a blanket is concentrated near the first wall. Uniform liquid-metal velocity in a self-cooled blanket is unattractive, because it leads to low mixed-mean temperature rise through the blanket and reduced power conversion efficiency. The objective of MHD flow control is to use the electromagnetic forces to produce a non-uniform velocity distribution which gives a uniform temperature distribution over the thickness of the blanket. Three methods of MHD flow control are presented here and the MHD pressure drops corresponding to the three methods are compared. One of the methods, although successful at achieving nonuniform velocity profiles, permits a large circulation of electric current which produces a high pressure drop. The analytical results do not indicate a clear choice between the other two methods. The analytical results do point to possible difference in heat transfer performance with the two methods.

  12. New frontiers in teaching and learning English

    CERN Document Server

    Vettorel, Paola

    2015-01-01

    The contributions to this volume explore several focal issues related to the global spread of English and their implications for English language teaching, providing both theoretical and empirical perspectives on recent research and implications in educational terms. The volume is divided into three thematic sections, namely ""Developments in ELF research and pedagogic implications"", ""Raising teachers' awareness of ELF"", and ""ELF and ELT practices"". The book provides up-to-date perspectives on the issues, implications and repercussions that findings in ELF research can have for ELT practi

  13. The new frontier of public health education.

    Science.gov (United States)

    Birnbaum, David; Gretsinger, Kathryn; Ellis, Ursula

    2017-02-06

    Purpose The aim of this paper is to describe the experience and educational benefits of a course that has several unique educational design features. Design/methodology/approach This includes narrative description of faculty and student experience from participants in a flipped-instructional-design inter-professional education course. Findings "Improving Public Health - An Interprofessional Approach to Designing and Implementing Effective Interventions" is an undergraduate public health course open to students regardless of background. Its student activities mirror the real-life tasks and challenges of working in a public health agency, including team-building and leadership; problem and project definition and prioritization; evidence-finding and critical appraisal; written and oral presentation; and press interviews. Students successfully developed project proposals to address real problems in a wide range of communities and settings and refined those proposals through interaction with professionals from population and public health, journalism and library sciences. Practical implications Undergraduate public health education is a relatively new endeavor, and experience with this new approach may be of value to other educators. Originality/value Students in this course, journalism graduate students who conducted mock interviews with them and instructors who oversaw the course all describe unique aspects and related personal benefit from this novel approach.

  14. Extreme-value statistics from Lagrangian convex hull analysis I. Validation for homogeneous turbulent Boussinesq convection and MHD convection

    CERN Document Server

    Pratt, J; Müller, W -C; Chapman, S C; Watkins, N W

    2016-01-01

    We investigate the utility of the convex hull to analyze physical questions related to the dispersion of a group of much more than four Lagrangian tracer particles in a turbulent flow. Validation of standard dispersion behaviors is a necessary preliminary step for use of the convex hull to describe turbulent flows. In simulations of statistically homogeneous and stationary Navier-Stokes turbulence, neutral fluid Boussinesq convection, and MHD Boussinesq convection we show that the convex hull can be used to reasonably capture the dispersive behavior of a large group of tracer particles. We validate dispersion results produced with convex hull analysis against scalings for Lagrangian particle pair dispersion. In addition to this basic validation study, we show that convex hull analysis provides information that particle pair dispersion does not, in the form of a extreme value statistics, surface area, and volume for a cluster of particles. We use the convex hull surface area and volume to examine the degree of...

  15. Magnetohydrodynamics MHD Engineering Test Facility ETF 200 MWe power plant. Conceptual Design Engineering Report CDER. Volume 3: Costs and schedules

    Science.gov (United States)

    1981-01-01

    The estimated plant capital cost for a coal fired 200 MWE electric generating plant with open cycle magnetohydrodynamics is divided into principal accounts based on Federal Energy Regulatory Commision account structure. Each principal account is defined and its estimated cost subdivided into identifiable and major equipment systems. The cost data sources for compiling the estimates, cost parameters, allotments, assumptions, and contingencies, are discussed. Uncertainties associated with developing the costs are quantified to show the confidence level acquired. Guidelines established in preparing the estimated costs are included. Based on an overall milestone schedule related to conventional power plant scheduling experience and starting procurement of MHD components during the preliminary design phase there is a 6 1/2-year construction period. The duration of the project from start to commercial operation is 79 months. The engineering phase of the project is 4 1/2 years; the construction duration following the start of the man power block is 37 months.

  16. MHD pressure drop characteristics in a three-surface-multi-layered channel under a strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Aoyagi, M., E-mail: mao@karma.qse.tohoku.ac.jp [Department of Quantum Science and Energy Engineering, School of Engineering, Tohoku University, 6-6-01-2 Aramaki-Aoba, Aoba-ku, Sendai 980-8579 (Japan); Ito, S.; Hashizume, H. [Department of Quantum Science and Energy Engineering, School of Engineering, Tohoku University, 6-6-01-2 Aramaki-Aoba, Aoba-ku, Sendai 980-8579 (Japan); Muroga, T. [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan)

    2010-12-15

    A three-surface-multi-layered channel is one of the possible methods for reducing the magnetohydrodynamic (MHD) pressure drop in a Li/V blanket. In this study, experimental and numerical evaluations of the liquid metal MHD flow in a three-surface-multi-layered channel were conducted to confirm the extent of MHD pressure reduction in the channel. The MHD flow was tested using a Bi-Sn eutectic alloy (MHD liquid) and an open annular channel under up to 5 T magnetic field. Experimentally determined pressure drops differed from those predicted by numerical analysis. This may be as a result of an increase in the friction force caused by an oxide appearing on the liquid free surface and a decrease in the electromagnetic force owing to the formation of a contact resistance between the Bi-Sn alloy and the bottom wall of the stainless steel channel.

  17. Frontiers in statistical quality control 11

    CERN Document Server

    Schmid, Wolfgang

    2015-01-01

    The main focus of this edited volume is on three major areas of statistical quality control: statistical process control (SPC), acceptance sampling and design of experiments. The majority of the papers deal with statistical process control, while acceptance sampling and design of experiments are also treated to a lesser extent. The book is organized into four thematic parts, with Part I addressing statistical process control. Part II is devoted to acceptance sampling. Part III covers the design of experiments, while Part IV discusses related fields. The twenty-three papers in this volume stem from The 11th International Workshop on Intelligent Statistical Quality Control, which was held in Sydney, Australia from August 20 to August 23, 2013. The event was hosted by Professor Ross Sparks, CSIRO Mathematics, Informatics and Statistics, North Ryde, Australia and was jointly organized by Professors S. Knoth, W. Schmid and Ross Sparks. The papers presented here were carefully selected and reviewed by the scientifi...

  18. Astronomy at the frontiers of science

    CERN Document Server

    2011-01-01

    Astronomy is by nature an interdisciplinary activity: it involves mathematics, physics, chemistry and biology. Astronomers use (and often develop) the latest technology, the fastest computers and the most refined software.  In this book twenty-two leading scientists from nine countries talk about how astronomy interacts with these other sciences. They describe modern instruments used in astronomy and the relations between astronomy and technology, industry, politics and philosophy. They also discuss what it means to be an astronomer, the history of astronomy, and the place of astronomy in society today.   The book contains twenty chapters grouped in four parts: ASTRONOMY AND PHYSICS discusses the place of astronomy among various branches of (mostly high-energy) physics. ASTRONOMY IN SOCIETY describes not only the historical context of astronomy, but issues facing astronomers today, including funding, planning, worldwide collaboration and links with industry. THE TOOLS OF OBSERVATION AND THE PROFESSION OF AS...

  19. Frontiers in Medicinal Chemistry 2017 in Bern, Switzerland.

    Science.gov (United States)

    Probst, Daniel; Heitz, Marc; Poirier, Marion; Gan, Bee Ha; Delalande, Clémence; Reymond, Jean-Louis

    2017-10-09

    Sharing capital ideas: The 2017 Frontiers in Medicinal Chemistry (FiMC) conference, organized jointly by the German Chemical Society, the German Pharmaceutical Society, and the Swiss Chemical Society, was held at the Department of Chemistry and Biochemistry of the University of Bern in February 2017. Herein we summarize the many conference highlights, and look forward to the next FiMC meeting, to be held in Jena (Germany) in March 2018. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. NATO Advanced Study Institute on Frontiers of Optical Spectroscopy

    CERN Document Server

    Bartolo, Baldassare

    2005-01-01

    Advanced spectroscopic techniques allow the probing of very small systems and very fast phenomena, conditions that can be considered "extreme" at the present status of our experimentation and knowledge. Quantum dots, nanocrystals and single molecules are examples of the former and events on the femtosecond scale examples of the latter. The purpose of this book is to examine the realm of phenomena of such extreme type and the techniques that permit their investigations. Each author has developed a coherent section of the program starting at a somewhat fundamental level and ultimately reaching the frontier of knowledge in the field in a systematic and didactic fashion. The formal lectures are complemented by additional seminars.