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Sample records for water thermo-capillary loop

  1. Experimental study of a water thermo-capillary loop; Etude experimentale d`une boucle thermocapillaire a eau

    Energy Technology Data Exchange (ETDEWEB)

    Lefriec, C.; Alexandre, A. [Ecole Nationale Superieure de Mecanique et d`Aerotechnique (ENSMA), 86 - Poitiers (France)

    1996-12-31

    This paper presents a bench scale experiment of a water thermo-capillary loop which allows to improve the understanding of its functioning mechanisms thanks to the internal visualisation of each component using transparent walls. The advantages of water are its non-toxicity, its high chemical compatibility with several materials and its low functioning pressure. The experimental device is presented and the functioning regimes of each component is analyzed: condenser (flow visualization, influence of tilt), evaporator (quality of heat exchange between teeth and porous medium, bubbles, heat exchange coefficient). (J.S.)

  2. An experimental investigation of thermo-capillary convection in solution of lithium bromide at non-isothermal absorption

    National Research Council Canada - National Science Library

    Bufetov N. S; Dekhtyar R. A; Ovchinikov V. V

    2016-01-01

    The aim of this work is to obtain new experimental data on the development of thermo-capillary convection in a solution of lithium bromide with non-isothermal absorption of water vapor in a confined vessel...

  3. An experimental investigation of thermo-capillary convection in solution of lithium bromide at non-isothermal absorption

    Directory of Open Access Journals (Sweden)

    Bufetov N. S.

    2016-09-01

    Full Text Available The aim of this work is to obtain new experimental data on the development of thermo-capillary convection in a solution of lithium bromide with non-isothermal absorption of water vapor in a confined vessel. In experiments the contactless method of measuring the temperature of the interface based on using thermal imaging equipment, and the visualization method of the flow arising in the absorbent layer by introducing markers into solution have been used. The immobile layer of lithium bromide solution with an initial concentration of 58 % and a layer thickness of 20 mm in a confined vessel of 70 mm in diameter has been chosen as an object of investigation. The water vapor has been used as the absorbed gas, whose pressure was kept constant during the absorption (approximately 2 000 Pa. The absorption process has started after the steam supply to the absorber where the initial pressure has corresponded to saturated water vapor pressure at the temperature of the solution (250–300 Pa. The speed and duration of convective motion in the layer absorption on the basis of imaging arising due to thermo-capillary convection have been measured. The thermograms of the interface for various operating parameters have been obtained with the development of thermo-concentration convection. The characteristic time of the thermo-capillary convection development has been determined. Based on the experimental data analysis the empirical expressions for duration of the convective motion depending on the vapor pressure in the absorber and the thickness of the absorbent layer have been proposed. It has been shown that lowering the initial temperature of the solution leads to enhancement of thermo-concentration convection. The results are useful for the design and optimization of elements of refrigeration engineering of the absorption type.

  4. Thermo capillary and buoyancy flows instabilities; Instabilites d`ecoulements thermocapillaires et de thermogravite

    Energy Technology Data Exchange (ETDEWEB)

    Mercier, J.F.

    1997-10-22

    Fluid flows in which liquid layers are submitted to temperature gradient applied horizontally are studied. The thermo capillary and buoyancy effects are thus described. In the experiments, the form of the cell which contains the fluid is different and the fluid heating position too. Each of these experiments reveals a different aspect of the mechanism which is responsible of the flow instability. In the first experiment, the fluid is contained in a rectangular cell longer than larger and whose two longer vertical walls are differentially heated. The waves lengths, frequencies, propagation directions and instability thresholds of stationary, unsteady or oscillating modes obtained theoretically are compared to the structures observed experimentally. The instability mechanisms are essentially bound to the temperature vertical profile in the fluid and the heat exchanges between the fluid and the ambient air are particularly described. In the second experiment, the fluid is contained in an annular cell whose vertical cylindrical walls are differentially heated. The results obtained in the rectangular cell can be transposed to the annular cell substituting the constant thermal gradient of the rectangular geometry by those of the annular geometry, inversely proportional to the radial distance. The introduction of local parameters allows to show that the instability is developed at first near the inside cylinder. In the last experiment, the fluid layer is heated by an electric wire immersed in a parallel direction to the free surface. The development of an ascending vertical flow above the wire induces a deformation of the free surface which can be added to the instability mechanisms of the previous cells. (O.M.) 58 refs.

  5. Thermo capillary and buoyancy convection in a fluid locally heated on its free surface; Convection thermocapillaire et thermogravitaire dans un fluide chauffe localement sur sa surface libre

    Energy Technology Data Exchange (ETDEWEB)

    Favre, E.

    1997-09-26

    coupled buoyancy and thermo-capillary convection lead to a convective motion of the interface liquid/gas which drastically changes the heat and mass transfer across the liquid layer. Two experiments were considered, depending on the fluid: oil or mercury. The liquid is set in a cooled cylindrical vessel, and heated by a heat flux across the center of the free surface. The basic flow, in the case of oil, is a torus. When the heat parameter increases, a stationary flow appears as petals or rays when the aspect ratio. The lateral confinement selects the azimuthal wavelength. In the case of petals-like flow, a sub-critical Hopf bifurcation is underlined. The turbulence is found to be `weak`, even for the largest values of the Marangoni number (Ma = 1.3 10{sup 5}). In the case of mercury, the thermo-capillary effect is reduced to zero to impurities at the surface which have special trajectories we describe and compare to a simpler experiment. Only the buoyancy forces induce a unstationary, weakly turbulent flow as soon as the heating power exceeds 4W (Ra = 4.5 10{sup 3}, calculated with h = 1 mm). The past part concerns the analysis of the effect on the flow of the boundary conditions, the geometry, the Prandtl number and the buoyancy force with the help of the literature. Results concerning heat transfer, in particular the exponent of the law Nusselt number vs. heating power, were compared with available data. (author) 115 refs.

  6. Supercritical water loop for in-pile materials testing

    Energy Technology Data Exchange (ETDEWEB)

    Ruzickova, M.; Vsolak, R.; Hajek, P.; Zychova, M.; Fukac, R. [Research Centre Rez Ltd., Husinec-Rez (Czech Republic)

    2011-07-01

    The Supercritical Water Loop (SCWL) has been designed and built within the HPLWR Phase 2 project, with the objective of testing materials under supercritical water conditions and radiation. The design parameters are set to 25MPa and 600{sup o}C in the testing area, where material samples shall be located. The loop has recently undergone pressure and leakage tests, during which the strength and tightness of the loop were proved. The loop has been also subjected to the first trial operation at nearly maximum operating parameters (temperature 550 {sup o}C was reached); loop operation was steady during several days. Presently, loop operation is envisaged in order to test the loop's long term operation ability. Samples of a material that needs further testing under out- of-pile conditions shall be exposed in the loop; the choice shall be made in agreement with the results of the WP4 - Materials of the HPLWR Phase 2 project. (author)

  7. Water Pipeline Network Analysis Using Simultaneous Loop Flow ...

    African Journals Online (AJOL)

    2013-03-01

    Mar 1, 2013 ... solving for the unknown in water network analysis. It is based on a loop iterative computation. Newton-Raphson method is a better technique for solving the network problems; however, the method adopted here computes simultaneous flow corrections for all loops, hence, the best since the computational.

  8. Storm water monitoring along loop 202 and Salt River.

    Science.gov (United States)

    2010-10-01

    A comprehensive research program for the characterization of storm water runoff from an Arizona : highway was conducted from January through December 2007. The study area covered a portion of : the Loop 202 freeway west of Mesa Drive to a retention b...

  9. NOMAGE4 activities 2011, Part II, Supercritical water loop

    DEFF Research Database (Denmark)

    Vierstraete, Pierre; Van Nieuwenhove, Rudi; Lauritzen, Bent

    and fuel tests. Working on this direction, the Halden Reactor Project has started an activity in collaboration with Risoe-DTU (with Mr. Rudi Van Nieuwenhove as the project leader) to study the feasibility of a SCW loop in the Halden Reactor, which is a Heavy Boiling Water Reactor (HBWR). The ultimate goal......The supercritical water reactor (SCWR) is one of the six different reactor technologies selected for research and development under the Generation IV program. Several countries have shown interest to this concept but up to now, there exist no in-pile facilities to perform the required material...

  10. NOMAGE4 activities 2011. Part II, Supercritical water loop

    Energy Technology Data Exchange (ETDEWEB)

    Vierstraete, P. (Ecole Nationale Superieure des mines, Paris (France)); Van Nieuwenhove, R. (Institutt for Energiteknikk, OECD Halden Reactor Project (HRP), Kjeller (Norway)); Lauritzen, B. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark))

    2012-01-15

    The supercritical water reactor (SCWR) is one of the six different reactor technologies selected for research and development under the Generation IV program. Several countries have shown interest to this concept but up to now, there exist no in-pile facilities to perform the required material and fuel tests. Working on this direction, the Halden Reactor Project has started an activity in collaboration with Risoe-DTU (with Mr. Rudi Van Nieuwenhove as the project leader) to study the feasibility of a SCW loop in the Halden Reactor, which is a Heavy Boiling Water Reactor (HBWR). The ultimate goal of the project is to design a loop allowing material and fuel test studies at significant mass flow with in-core instrumentation and chemistry control possibilities. The present report focusses on the main heat exchanger required for such a loop in the Halden Reactor. The goal of this heat exchanger is to assure a supercritical flow state inside the test section (the core side) and a subcritical flow state inside the pump section. The objective is to design the heat exchanger in order to optimize the efficiency of the heat transfer and to respect several requirements as the room available inside the reactor hall, the maximal total pressure drop allowed and so on. (Author)

  11. Performance of Water Recirculation Loop Maintenance Components for the Advanced Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Rector, Tony; Peyton, Barbara M.; Steele, John W.; Makinen, Janice; Bue, Grant C.; Campbell, Colin

    2014-01-01

    Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a second SWME water recirculation loop with no water quality maintenance. Results show the benefits of periodic water maintenance. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the evaluation of water recirculation maintenance components was to further enhance this advantage through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A bed design that was developed for a UTAS military application, and considered for a potential ISS application with the Urine Processor Assembly, provided a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for ISS to introduce a biocide in a microgravity compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

  12. Performance of Water Recirculation Loop Maintentance Components for the Advanced Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Rector, Tony; Peyton, Barbara; Steele, John W.; Bue, Grant C.; Campbell, Colin; Makinen, Janice

    2014-01-01

    Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a second SWME water recirculation loop with no water quality maintenance. Results show the benefits of periodic water maintenance. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the evaluation of water recirculation maintenance components was to further enhance this advantage through the leveraging of fluid loop management lessonslearned from the International Space Station (ISS). A bed design that was developed for a UTAS military application, and considered for a potential ISS application with the Urine Processor Assembly, provided a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for ISS to introduce a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

  13. Flow loop studies with AMAX coal-water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Wildman, D.J.; Ekmann, J.M.

    1984-03-01

    The coal-water mixtures (CWM) with a stabilizer and the CWM without stabilizers were successfully transported through a flow loop facility under a variety of conditions. The handling characteristics of both CWM were reasonable. The mix tank mixer was not needed during nontesting hours to prevent settling of either material. After several days of transporting the nonstabilized material in the loop facility, the viscosity-reducing agent became ineffective. It was necessary to increase the concentration of the viscosity-reducing agent. The material with stabilizer could not be transported through the loop facility at mass flow rates greater than 209 lb/min until overnight shearing of the CWM in the tank. The CWM without a stabilizer appeared to be slightly shear-thickening, whereas the stabilized CWM initially exhibited shear-thinning behavior. The pressure losses measured for the nonstabilized material were similar to the pressure losses measured for CWM prepared at PETC with three or four percent higher concentration of Pittsburgh seam coal. Tests performed with the stabilized CWM experienced pressure losses similar to CWM prepared at PETC with Pittsburgh seam coal of five to seven percent higher concentration. Tests 1A, 2A, 1B, and 2B were not included in the comparison of in-house-prepared CWM due to differences in pretest handling procedures. 1 figure, 2 tables.

  14. Integral-type solar water heater using loop heat pipe

    Energy Technology Data Exchange (ETDEWEB)

    Huang, B.J.; Yang, P.E.; Wang, J.H.; Wu, J.H. [New Energy Center, Taiwan Univ., Taipei (China)

    2008-07-01

    Taiwan University has been devoted to the development of low-cost LHP (loop hat pipe). A new manufacturing process for low-cost LHP has been developed that leads to a cost down to less than 10 USD for a 100W LHP. The present study utilizes the low-cost LHP to develop a new type of solar water heater. A thermosyphon which is thermally bonded with a solar absorber plate is used to absorb solar energy and transfer the heat upward to the evaporator of the LHP. From that, the heat is conducted downward to the condenser of the LHP which is immersed in a hot water tank beneath the solar collector. The solar water heater thus can be designed in integral type with streamline shape which is easy to install and has a good outlook as well as high efficiency. A prototype was designed and fabricated in the present study. A preliminary heat transfer test for a single unit of thermosyphon-LHP combination shows that it is capable of transferring the absorbed energy downward to the LHP condenser immersed in a hot water tank. The overall thermal resistance from the absorber plate to water is 0.34 C/W. and the thermal resistance of the LHP is 0.16 C/W. Two prototypes of the solar water heaters with 50 liters and 80 liters hot water tanks were designed according to the results of the feasibility test. In addition, an automatic monitoring system was designed and set up for the performance test of these two solar water heaters based on the test standard CNS B7277. The measured overall thermal resistance from solar absorber plate to water is 0.369 C/W. The daily solar water heater efficiency is 0.503. The present study has shown that the application of low-cost LHP in solar water heater is feasible and cost competitive. (orig.)

  15. Neutron Commissioning in the New CABRI Water Loop Facility

    Science.gov (United States)

    Ritter, G.; Gueton, O.; Mellier, F.; Beretz, D.

    2010-10-01

    The CABRI experimental reactor is located at the Cadarache nuclear research center, southern France. It is operated by the Atomic Energy Commission (CEA) and devoted to Institut de Radioprotection et de Sûreté Nucléaire (IRSN) safety programs. It has been successfully operated during the last 30 years, enlightening the knowledge of FBR and LWR fuel behavior during Reactivity Insertion Accident (RIA) and Loss Of Coolant Accident (LOCA) transients in the frame of Institut de Protection et de Sûreté Nucléaire (IPSN) and now IRSN programs devoted to reactor safety. This operation was interrupted in 2003 to allow for a whole facility renewal program. The main goal of this reconstruction project is to meet thermal hydraulics parameters identical to LWR standard and downgraded conditions, in particular for the need of the CABRI International Programme (CIP) carried out by IRSN under the OECD umbrella. For this, the sodium cooled experimental loop is now being replaced by a pressurized water loop. The distinctive features of CABRI core allow for a specific neutron commissioning program. This paper presents the parameters to be measured with associated experimental methods and also briefly introduces the instrumentation set up.

  16. Solutions of selected pseudo loop equations in water distribution ...

    African Journals Online (AJOL)

    This paper demonstrated the use of Microsoft Excel Solver (a computer package) in solving selected pseudo loop equations in pipe network analysis problems. Two pipe networks with pumps and overhead tanks were used to demonstrate the use of Microsoft Excel Solver in solving pseudo loops (open loops; networks with ...

  17. Supercritical water loop design for corrosion and water chemistry tests under irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ruzickova, Mariana; Hajek, Petr; Vsolak, Rudolf; Kysela, Jan [Nuclear Research Institute Rez plc, Reactor Services Division, Husinec (Czech Republic); Smida, Stepan [H and D Engineering, Praha (Czech Republic); Petr, Jan [Nuclear Research Institute Rez plc, Praha (Czech Republic)

    2008-03-15

    An experimental loop operating with water at supercritical conditions (25MPa, 600 .deg. C in the test section) is designed for operation in the research reactor LVR-15 in UJV Rez, Czech Republic. The loop should serve as an experimental facility for corrosion tests of materials for in-core as well as out-of-core structures, for testing and optimization of suitable water chemistry for a future HPLWR and for studies of radiolysis of water at supercritical conditions, which remains the domain where very few experimental data are available. At present, final necessary calculations (thermalhydraulic, neutronic, strength) are being performed on the irradiation channel, which is the most challenging part of the loop. The concept of the primary and auxiliary circuits has been completed. The design of the loop shall be finished in the course of the year 2007 to start the construction, out-of-pile testing to verify proper functioning of all systems and as such to be ready for in-pile tests by the end of the HPLWR Phase 2 European project by the end of 2009.

  18. Thermal Interface Evaluation of Heat Transfer from a Pumped Loop to Titanium-Water Thermosyphons

    Science.gov (United States)

    Jaworske, Donald A.; Sanzi, James L.; Gibson, Marc A.; Sechkar, Edward A.

    2009-01-01

    Titanium-water thermosyphons are being considered for use in the heat rejection system for lunar outpost fission surface power. Key to their use is heat transfer between a closed loop heat source and the heat pipe evaporators. This work describes laboratory testing of several interfaces that were evaluated for their thermal performance characteristics, in the temperature range of 350 to 400 K, utilizing a water closed loop heat source and multiple thermosyphon evaporator geometries. A gas gap calorimeter was used to measure heat flow at steady state. Thermocouples in the closed loop heat source and on the evaporator were used to measure thermal conductance. The interfaces were in two generic categories, those immersed in the water closed loop heat source and those clamped to the water closed loop heat source with differing thermal conductive agents. In general, immersed evaporators showed better overall performance than their clamped counterparts. Selected clamped evaporator geometries offered promise.

  19. Radiant Cooling for Closed-Loop Water Containment: Exploration of Possible Application in Dry Docks

    Science.gov (United States)

    2015-08-20

    Radiant Cooling For Closed-Loop Water Containment: Exploration of Possible Application in Dry Docks by Trevor R. Murphy, Mechanical...Organization: SPAWAR Sponsoring Organization: NESDI Keywords: Dry Dock Cooling, Heat Transfer, Closed Loop, Pipe System, Cost, Pareto List of Programs...provide data for estimating the cost of implementing a closed-loop radiant cooling system for ships in dry docks . Depending on the material used, pipe

  20. Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Rector, Tony; Steele, John W.; Bue, Grant C.; Campbell, Colin; Makinen, Janice

    2012-01-01

    A water loop maintenance device and process to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been undergoing a performance evaluation. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the water recirculation maintenance device and process is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance process further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware. This

  1. Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

    2012-01-01

    A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high-capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit Transport Water Loop. The bed design further leverages a sorbent developed for the ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System. The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of crewed spaceflight Environmental Control and Life Support System hardware.

  2. Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

    2013-01-01

    A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The bed design further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

  3. Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

    2011-01-01

    A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The bed design further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a clear demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

  4. Coral mucus fuels the sponge loop in warm- and cold-water coral reef ecosystems.

    Science.gov (United States)

    Rix, Laura; de Goeij, Jasper M; Mueller, Christina E; Struck, Ulrich; Middelburg, Jack J; van Duyl, Fleur C; Al-Horani, Fuad A; Wild, Christian; Naumann, Malik S; van Oevelen, Dick

    2016-01-07

    Shallow warm-water and deep-sea cold-water corals engineer the coral reef framework and fertilize reef communities by releasing coral mucus, a source of reef dissolved organic matter (DOM). By transforming DOM into particulate detritus, sponges play a key role in transferring the energy and nutrients in DOM to higher trophic levels on Caribbean reefs via the so-called sponge loop. Coral mucus may be a major DOM source for the sponge loop, but mucus uptake by sponges has not been demonstrated. Here we used laboratory stable isotope tracer experiments to show the transfer of coral mucus into the bulk tissue and phospholipid fatty acids of the warm-water sponge Mycale fistulifera and cold-water sponge Hymedesmia coriacea, demonstrating a direct trophic link between corals and reef sponges. Furthermore, 21-40% of the mucus carbon and 32-39% of the nitrogen assimilated by the sponges was subsequently released as detritus, confirming a sponge loop on Red Sea warm-water and north Atlantic cold-water coral reefs. The presence of a sponge loop in two vastly different reef environments suggests it is a ubiquitous feature of reef ecosystems contributing to the high biogeochemical cycling that may enable coral reefs to thrive in nutrient-limited (warm-water) and energy-limited (cold-water) environments.

  5. Optimal Pipe Size Design for Looped Irrigation Water Supply System Using Harmony Search: Saemangeum Project Area

    Science.gov (United States)

    Lee, Ho Min; Sadollah, Ali

    2015-01-01

    Water supply systems are mainly classified into branched and looped network systems. The main difference between these two systems is that, in a branched network system, the flow within each pipe is a known value, whereas in a looped network system, the flow in each pipe is considered an unknown value. Therefore, an analysis of a looped network system is a more complex task. This study aims to develop a technique for estimating the optimal pipe diameter for a looped agricultural irrigation water supply system using a harmony search algorithm, which is an optimization technique. This study mainly serves two purposes. The first is to develop an algorithm and a program for estimating a cost-effective pipe diameter for agricultural irrigation water supply systems using optimization techniques. The second is to validate the developed program by applying the proposed optimized cost-effective pipe diameter to an actual study region (Saemangeum project area, zone 6). The results suggest that the optimal design program, which applies an optimization theory and enhances user convenience, can be effectively applied for the real systems of a looped agricultural irrigation water supply. PMID:25874252

  6. TREAT Neutronics Analysis of Water-Loop Concept Accommodating LWR 9-rod Bundle

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Connie M.; Woolstenhulme, Nicolas E.; Parry, James R.; Bess, John D.; Housley, Gregory K.

    2016-09-01

    Abstract. Simulation of a variety of transient conditions has been successfully achieved in the Transient Reactor Test (TREAT) facility during operation between 1959 and 1994 to support characterization and safety analysis of nuclear fuels and materials. A majority of previously conducted tests were focused on supporting sodium-cooled fast reactor (SFR) designs. Experiments evolved in complexity. Simulation of thermal-hydraulic conditions expected to be encountered by fuels and materials in a reactor environment was realized in the development of TREAT sodium loop experiment vehicles. These loops accommodated up to 7-pin fuel bundles and served to simulate more closely the reactor environment while safely delivering large quantities of energy into the test specimen. Some of the immediate TREAT restart operations will be focused on testing light water reactor (LWR) accident tolerant fuels (ATF). Similar to the sodium loop objectives, a water loop concept, developed and analyzed in the 1990’s, aimed at achieving thermal-hydraulic conditions encountered in commercial power reactors. The historic water loop concept has been analyzed in the context of a reactivity insertion accident (RIA) simulation for high burnup LWR 2-pin and 3-pin fuel bundles. Findings showed sufficient energy could be deposited into the specimens for evaluation. Similar results of experimental feasibility for the water loop concept (past and present) have recently been obtained using MCNP6.1 with ENDF/B-VII.1 nuclear data libraries. The old water loop concept required only two central TREAT core grid spaces. Preparation for future experiments has resulted in a modified water loop conceptual design designated the TREAT water environment recirculating loop (TWERL). The current TWERL design requires nine TREAT core grid spaces in order to place the water recirculating pump under the TREAT core. Due to the effectiveness of water moderation, neutronics analysis shows that removal of seven additional

  7. A combined NLP-differential evolution algorithm approach for the optimization of looped water distribution systems

    Science.gov (United States)

    Zheng, Feifei; Simpson, Angus R.; Zecchin, Aaron C.

    2011-08-01

    This paper proposes a novel optimization approach for the least cost design of looped water distribution systems (WDSs). Three distinct steps are involved in the proposed optimization approach. In the first step, the shortest-distance tree within the looped network is identified using the Dijkstra graph theory algorithm, for which an extension is proposed to find the shortest-distance tree for multisource WDSs. In the second step, a nonlinear programming (NLP) solver is employed to optimize the pipe diameters for the shortest-distance tree (chords of the shortest-distance tree are allocated the minimum allowable pipe sizes). Finally, in the third step, the original looped water network is optimized using a differential evolution (DE) algorithm seeded with diameters in the proximity of the continuous pipe sizes obtained in step two. As such, the proposed optimization approach combines the traditional deterministic optimization technique of NLP with the emerging evolutionary algorithm DE via the proposed network decomposition. The proposed methodology has been tested on four looped WDSs with the number of decision variables ranging from 21 to 454. Results obtained show the proposed approach is able to find optimal solutions with significantly less computational effort than other optimization techniques.

  8. Entropy and free energy of a mobile protein loop in explicit water.

    Science.gov (United States)

    Cheluvaraja, Srinath; Mihailescu, Mihail; Meirovitch, Hagai

    2008-08-07

    Estimation of the energy from a given Boltzmann sample is straightforward since one just has to average the contribution of the individual configurations. On the other hand, calculation of the absolute entropy, S (hence the absolute free energy F) is difficult because it depends on the entire (unknown) ensemble. We have developed a new method called "the hypothetical scanning molecular dynamics" (HSMD) for calculating the absolute S from a given sample (generated by any simulation technique). In other words, S (like the energy) is "written" on the sample configurations, where HSMD provides a prescription of how to "read" it. In practice, each sample conformation, i, is reconstructed with transition probabilities, and their product leads to the probability of i, hence to the entropy. HSMD is an exact method where all interactions are considered, and the only approximation is due to insufficient sampling. In previous studies HSMD (and HS Monte CarloHSMC) has been extended systematically to systems of increasing complexity, where the most recent is the seven-residue mobile loop, 304-310 (Gly-His-Gly-Ala-Gly-Gly-Ser) of the enzyme porcine pancreatic alpha-amylase modeled by the AMBER force field and AMBER with the implicit solvation GB/SA (paper I, Cheluvaraja, S.; Meirovitch, H. J. Chem. Theory Comput. 2008, 4, 192). In the present paper we make a step further and extend HSMD to the same loop capped with TIP3P explicit water at 300 K. As in paper I, we are mainly interested in entropy and free energy differences between the free and bound microstates of the loop, which are obtained from two separate MD samples of these microstates. The contribution of the loop to S and F is calculated by HSMD and that of water by a particular thermodynamic integration procedure. As expected, the free microstate is more stable than the bound microstate by a total free energy difference, Ffree-Fbound=-4.8+/-1, as compared to -25.5 kcal/mol obtained with GB/SA. We find that relatively

  9. The simulation of thermohydraulic phenomena in a pressurized water reactor primary loop

    Energy Technology Data Exchange (ETDEWEB)

    Popp, M

    1987-01-01

    Several important fluid flow and heat transfer phenomena essential to nuclear power reactor safety were investigated. Scaling and modeling laws for pressurized water reactors are reviewed and a new scaling approach focusing on the overall loop behavior is presented. Scaling criteria for one- and two-phase natural circulation are developed, as well as a simplified model describing the first phase of a small break loss of coolant accident. Reactor vessel vent valve effects are included in the analysis of steady one-phase natural circulation flow. Two new dimensionless numbers, which uniquely describe one-phase flow in natural circulation loops, were deduced and are discussed. A scaled model of the primary loop of a typical Babcock and Wilcox reactor was designed, built, and tested. The particular prototype modeled was the TMI unit 2 reactor. The electrically heated, stainless steel model operates at a maximum pressure of 300 psig and has a maximum heat input of 188 kW. The model is about 4 times smaller in height than the prototype reactor, with a nominal volume scale of 1:500. Experiments were conducted establishing subcooled natural circulation in the model loop. Both steady flow and power transients were investigated.

  10. Cutting a drop of water pinned by wire loops using a superhydrophobic surface and knife.

    Directory of Open Access Journals (Sweden)

    Ryan Yanashima

    Full Text Available A water drop on a superhydrophobic surface that is pinned by wire loops can be reproducibly cut without formation of satellite droplets. Drops placed on low-density polyethylene surfaces and Teflon-coated glass slides were cut with superhydrophobic knives of low-density polyethylene and treated copper or zinc sheets, respectively. Distortion of drop shape by the superhydrophobic knife enables a clean break. The driving force for droplet formation arises from the lower surface free energy for two separate drops, and it is modeled as a 2-D system. An estimate of the free energy change serves to guide when droplets will form based on the variation of drop volume, loop spacing and knife depth. Combining the cutting process with an electrofocusing driving force could enable a reproducible biomolecular separation without troubling satellite drop formation.

  11. Long Duration Life Test of Propylene Glycol Water Based Thermal Fluid Within Thermal Control Loop

    Science.gov (United States)

    Le, Hung; Hill, Charles; Stephan, Ryan A.

    2010-01-01

    Evaluations of thermal properties and resistance to microbial growth concluded that 50% Propylene Glycol (PG)-based fluid and 50% de-ionized water mixture was desirable for use as a fluid within a vehicle s thermal control loop. However, previous testing with a commercial mixture of PG and water containing phosphate corrosion inhibitors resulted in corrosion of aluminum within the test system and instability of the test fluid. This paper describes a follow-on long duration testing and analysis of 50% Propylene Glycol (PG)-based fluid and 50% de-ionized water mixture with inorganic corrosion inhibitors used in place of phosphates. The test evaluates the long-term fluid stability and resistance to microbial and chemical changes

  12. Study and Optimization of Design Parameters in Water Loop Heat Pump Systems for Office Buildings in the Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    Francisco Javier Fernández

    2017-11-01

    Full Text Available Water loop heat pump (WLHP air conditioning systems use heat pumps connected to a common water circuit to fulfill the energy demands of different thermal zones in a building. In this study, the energy consumption was analyzed for the air conditioning of an office building in the typical climate of four important cities of the Iberian Peninsula. The energy consumption of one water loop heat pump system was compared with a conventional water system. Two design parameters, the range in the control temperatures and the water loop thermal storage size, were tested. Energy redistribution is an important advantage of the WLHP system, but significant savings came from high efficiency parameters in the heat pumps and minor air flow rates in the cooling tower. The low thermal level in the water loop makes this technology appropriate to combine with renewable sources. Using natural gas as the thermal energy source, a mean decrease in CO2 emissions of 8.1% was reached. Simulations showed that the installation of big thermal storage tanks generated small energy savings. Besides, the total annual consumption in buildings with high internal loads can be reduced by keeping the water loop as cool as possible.

  13. Efforts to Reduce International Space Station Crew Maintenance for the Management of the Extravehicular Mobility Unit Transport Loop Water Quality

    Science.gov (United States)

    Steele, John W.; Etter, David; Rector, Tony; Boyle, Robert; Vandezande, Christopher

    2013-01-01

    The EMU (Extravehicular Mobility Unit) contains a semi-closed-loop re-circulating water circuit (Transport Loop) to absorb heat into a LCVG (Liquid Coolant and Ventilation Garment) worn by the astronaut. A second, single-pass water circuit (Feed-water Loop) provides water to a cooling device (Sublimator) containing porous plates, and that water sublimates through the porous plates to space vacuum. The cooling effect from the sublimation of this water translates to a cooling of the LCVG water that circulates through the Sublimator. The quality of the EMU Transport Loop water is maintained through the use of a water processing kit (ALCLR Airlock Cooling Loop Remediation) that is used to periodically clean and disinfect the water circuit. Opportunities to reduce crew time associated with on-orbit ALCLR operations include a detailed review of the historical water quality data for evidence to support an extension to the implementation cycle. Furthermore, an EMU returned after 2-years of use on the ISS (International Space Station) is being used as a test bed to evaluate the results of extended and repeated ALCLR implementation cycles. Finally, design, use and on-orbit location enhancements to the ALCLR kit components are being considered to allow the implementation cycle to occur in parallel with other EMU maintenance and check-out activities, and to extend the life of the ALCLR kit components. These efforts are undertaken to reduce the crew-time and logistics burdens for the EMU, while ensuring the long-term health of the EMU water circuits for a post-Shuttle 6-year service life.

  14. Dynamic Characterization of a Low Cost Microwave Water-Cut Sensor in a Flow Loop

    KAUST Repository

    Karimi, Muhammad Akram

    2017-03-31

    Inline precise measurement of water fraction in oil (i.e. water-cut [WC]) finds numerous applications in oil and gas industry. This paper presents the characterization of an extremely low cost, completely non-intrusive and full range microwave water-cut sensor based upon pipe conformable microwave T-resonator. A 10″ microwave stub based T-resonator has been implemented directly on the pipe surface whose resonance frequency changes in the frequency band of 90MHz–190MHz (111%) with changing water fraction in oil. The designed sensor is capable of detecting even small changes in WC with a resolution of 0.07% at low WC and 0.5% WC at high WC. The performance of the microwave WC sensor has been tested in an in-house flow loop. The proposed WC sensor has been characterized over full water-cut range (0%–100%) not only in vertical but also in horizontal orientation. The sensor has shown predictable response in both orientations with huge frequency shift. Moreover, flow rate effect has also been investigated on the proposed WC sensor’s performance and it has been found that the sensor’s repeatability is within 2.5% WC for variable flow rates.

  15. The integration of water loop heat pump and building structural thermal storage systems

    Energy Technology Data Exchange (ETDEWEB)

    Marseille, T.J.; Schliesing, J.S.

    1991-10-01

    Many commercial buildings need heat in one part and, at the same time, cooling in another part. Even more common is the need for heating during one part of the day and cooling during another in the same spaces. If that energy could be shifted or stored for later use, significant energy might be saved. If a building's heating and cooling subsystems could be integrated with the building's structural mass and used to collect, store, and deliver energy, the energy might be save cost-effectively. To explore this opportunity, researchers at the Pacific Northwest Laboratory (PNL) examined the thermal interactions between the heating, ventilating, and air-conditioning (HVAC) system and the structure of a commercial building. Computer models were developed to simulate the interactions in an existing building located in Seattle, Washington, to determine how these building subsystems could be integrated to improve energy efficiency. The HVAC subsystems in the existing building were modeled. These subsystems consist of decentralized water-source heat pumps (WSHP) in a closed water loop, connected to cooling towers for heat rejection during cooling mode and boilers to augment heating. An initial base case'' computer model of the Seattle building, as-built, was developed. Metered data available for the building were used to calibrate this model to ensure that the analysis would provide information that closely reflected the operation of a real building. The HVAC system and building structure were integrated in the model using the concrete floor slabs as thermal storage media. The slabs may be actively charged during off-peak periods with the chilled water in the loop and then either actively or passively discharged into the conditioned space during peak periods. 21 refs., 37 figs., 17 tabs.

  16. Numerical comparison of thermal hydraulic aspects of supercritical carbon dioxide and subcritical water-based natural circulation loop

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Milan Krishna Singhar; Basu, Dipankar Narayan [Dept. of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati (India)

    2017-02-15

    Application of the supercritical condition in reactor core cooling needs to be properly justified based on the extreme level of parameters involved. Therefore, a numerical study is presented to compare the thermalhydraulic performance of supercritical and single-phase natural circulation loops under low-to-intermediate power levels. Carbon dioxide and water are selected as respective working fluids, operating under an identical set of conditions. Accordingly, a three-dimensional computational model was developed, and solved with an appropriate turbulence model and equations of state. Large asymmetry in velocity and temperature profiles was observed in a single cross section due to local buoyancy effect, which is more prominent for supercritical fluids. Mass flow rate in a supercritical loop increases with power until a maximum is reached, which subsequently corresponds to a rapid deterioration in heat transfer coefficient. That can be identified as the limit of operation for such loops to avoid a high temperature, and therefore, the use of a supercritical loop is suggested only until the appearance of such maxima. Flow-induced heat transfer deterioration can be delayed by increasing system pressure or lowering sink temperature. Bulk temperature level throughout the loop with water as working fluid is higher than supercritical carbon dioxide. This is until the heat transfer deterioration, and hence the use of a single-phase loop is prescribed beyond that limit.

  17. Numerical Comparison of Thermalhydraulic Aspects of Supercritical Carbon Dioxide and Subcritical Water-Based Natural Circulation Loop

    Directory of Open Access Journals (Sweden)

    Milan Krishna Singha Sarkar

    2017-02-01

    Full Text Available Application of the supercritical condition in reactor core cooling needs to be properly justified based on the extreme level of parameters involved. Therefore, a numerical study is presented to compare the thermalhydraulic performance of supercritical and single-phase natural circulation loops under low-to-intermediate power levels. Carbon dioxide and water are selected as respective working fluids, operating under an identical set of conditions. Accordingly, a three-dimensional computational model was developed, and solved with an appropriate turbulence model and equations of state. Large asymmetry in velocity and temperature profiles was observed in a single cross section due to local buoyancy effect, which is more prominent for supercritical fluids. Mass flow rate in a supercritical loop increases with power until a maximum is reached, which subsequently corresponds to a rapid deterioration in heat transfer coefficient. That can be identified as the limit of operation for such loops to avoid a high temperature, and therefore, the use of a supercritical loop is suggested only until the appearance of such maxima. Flow-induced heat transfer deterioration can be delayed by increasing system pressure or lowering sink temperature. Bulk temperature level throughout the loop with water as working fluid is higher than supercritical carbon dioxide. This is until the heat transfer deterioration, and hence the use of a single-phase loop is prescribed beyond that limit.

  18. Water Recovery from Brines to Further Close the Water Recovery Loop in Human Spaceflight

    Science.gov (United States)

    Jackson, W. Andrew; Barta, Daniel J.; Anderson, Molly S.; Lange, Kevin E.; Hanford, Anthony J.; Shull, Sarah A.; Carter, D. Layne

    2014-01-01

    Further closure of water recovery systems will be necessary for future long duration human exploration missions. NASA's Space Technology Roadmap for Human Health, Life Support and Habitation Systems specified a milestone to advance water management technologies during the 2015 to 2019 timeframe to achieve 98% H2O recovery from a mixed wastewater stream containing condensate, urine, hygiene, laundry, and water derived from waste. This goal can only be achieved by either reducing the amount of brines produced by a water recovery system or by recovering water from wastewater brines. NASA convened a Technical Interchange Meeting (TIM) on the topic of Water Recovery from Brines (WRB) that was held on January14-15th, 2014 at Johnson Space Center. Objectives of the TIM were to review systems and architectures that are sources of brines and the composition of brines they produce, review the state of the art in NASA technology development and perspectives from other industries, capture the challenges and difficulties in developing brine processing hardware, identify key figures of merit and requirements to focus technology development and evaluate candidate technologies, and identify other critical issues including microgravity sensitivity, and concepts of operation, safety. This paper represents an initial summary of findings from the workshop.

  19. Recovery Act: Cedarville School District Retrofit of Heating and Cooling Systems with Geothermal Heat Pumps and Ground Source Water Loops

    Energy Technology Data Exchange (ETDEWEB)

    Jarrell, Mark

    2013-09-30

    Cedarville School District retrofitted the heating and cooling systems in three campus areas (High School, Middle School, and Upper Elementary School) with geothermal heat pumps and ground source water loops, as a demonstration project for the effective implementation of geothermal heat pump systems and other energy efficiency and air quality improvements.

  20. Operation Experiences of the Small Scale Nitrogen Loop with a Water-Cooling Printed Circuit Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan Soo; Seo, Dong Un; Yoo, Tae Ho; Hong, Sung Deok; Kim, Yong Wan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-10-15

    A small scale nitrogen loop is in-operation for the integrity and feasibility test of the hybrid-concept sulfur trioxide decomposer. The small-scale gas loop takes the place of the hot gas and the process gas loop. The hot gas loop simulates the intermediate loop of a nuclear hydrogen production system in that it is designed to withstand the maximum temperature of 1273K, the maximum pressure of 6.0 MPa, and to operate at a mass flow rate of 2.0 kg/min with 4.0 MPa. Nitrogen is used as the working fluid for simple high pressure gas experiments. The fluid temperature is controlled by adjusting the power of the heaters using direct voltage controllers. The accumulator maintains the primary system at the constant pressure. The inverter of the circulator and the bypass flow valve control the primary mass flow rate. In this paper, the operating experience is presented to estimate the performance of the primary system. A water-cooling printed circuit heat exchanger was used to cool the hot gas into the room temperature

  1. Effect of cholera toxin on glucose absorption and net movements of water and electrolytes in the intestinal loop of sheep.

    Science.gov (United States)

    Hyun, H S; Onaga, T; Mineo, H; Kim, J T; Kato, S

    1996-12-01

    This study was designed to evaluate the effect of cholera toxin on glucose absorption and net movement of water and electrolytes in the jejunal loop of sheep. Intraluminal perfusion was performed at the rate of 1 ml/min with isotonic 10 mM glucose solution. Osmolality was adjusted by adding NaCl, and the outflow solution was collected every 10 min. After a 30 min control period, cholera toxin was applied intraluminally for 30 min at doses of 30, 60, and 120 micrograms/loop. In the control period, water, sodium and chloride were absorbed, while potassium and bicarbonate were secreted. Cholera toxin reversed the net absorption of water, sodium and chloride to net secretions, and this secretory response to cholera toxin was dose-dependent. Bicarbonate secretion was stimulated dose-dependently by cholera toxin. Potassium secretion was also increased at all doses, though this response was not dose-dependent. The net glucose absorption was decreased dose-dependently by cholera toxin. In conclusion, these results indicate that cholera toxin stimulates water and electrolyte secretion, and inhibits glucose absorption in the jejunal loop of sheep.

  2. Using Causal Loop Diagramming to Explore the Drivers of the Sustained Functionality of Rural Water Services in Timor-Leste

    Directory of Open Access Journals (Sweden)

    Kate Neely

    2016-01-01

    Full Text Available It is recognized that international water sector development work has issues with a lack of sustained positive outcomes. A large driver of this outcome is how NGOs work with communities to implement and then manage water services. Many NGOs tend to focus their efforts on improving their reach and organisational growth by continually engaging in new projects. This behaviour is largely driven by short-term donor funding models that reward extended coverage, leaving little focus on sustained outcomes. Similarly, community-based management (CBM schemes often impede sustained services as a result of the community’s limited capacity to operate and maintain the technology. To explore these complicated drivers on water service sustainability, we used causal loop diagramming to analyse the key aspect influencing the combined dynamics between NGOs, donors and CBM. We demonstrate this methodology through a study in Timor-Leste, where we gathered data necessary to develop and apply causal loop diagrams to analyse rural water supply program outcomes. The analysis of these diagrams allowed identification of leverage points used to suggest structural changes for sustained benefits of water services. These structural changes emphasize the importance of increased robustness and reliability of water technology and the associated impact this has on community satisfaction and, conjointly, on water service sustainability.

  3. Design, Construction and Testing of an In-Pile Loop for PWR (Pressurized Water Reactor) Simulation.

    Science.gov (United States)

    1987-06-01

    concentrations. It was found that raising coolant pH would decrease visual crud concentrations, but steam generator plenum and primary coolant pipe wall...built, the Loop duplicates the core and Steam Generator fluid surface film differential temperatures, bulk fluid temperatures, and wall fluid shear...2.4.2 Loop Plenum Design 39 2.4.3 Neutron Absorber Plug 44 2.4.4 Plenum Section Instrumentation 45 2.5 Steam Generator /Heat Rejection Section 45 5 2.5.1

  4. Power-level regulation and simulation of nonlinear pressurized water reactor core with xenon oscillation using H-infinity loop shaping control

    Directory of Open Access Journals (Sweden)

    Li Gang

    2016-01-01

    Full Text Available This investigation is to solve the power-level control issue of a nonlinear pressurized water reactor core with xenon oscillations. A nonlinear pressurized water reactor core is modeled using the lumped parameter method, and a linear model of the core is then obtained through the small perturbation linearization way. The H∞loop shapingcontrolis utilized to design a robust controller of the linearized core model.The calculated H∞loop shaping controller is applied to the nonlinear core model. The nonlinear core model and the H∞ loop shaping controller build the nonlinear core power-level H∞loop shaping control system.Finally, the nonlinear core power-level H∞loop shaping control system is simulatedconsidering two typical load processes that are a step load maneuver and a ramp load maneuver, and simulation results show that the nonlinear control system is effective.

  5. Magnetic endoscope imaging (ScopeGuide) elucidates the mechanism of action of the pain-alleviating impact of water exchange colonoscopy - attenuation of loop formation.

    Science.gov (United States)

    Leung, Joseph W; Thai, Anne; Yen, Andrew; Ward, Gregory; Abramyan, Ovanes; Lee, Jason; Smith, Brandon; Leung, Felix

    2012-07-01

    The explanation why water exchange colonoscopy produces a significant reduction of pain during colonoscopy is unknown. A recent editorial recommended use of magnetic endoscope imaging (MEI) to elucidate the explanation. In unselected patients to show that MEI documents less frequent loop formation when water exchange is used. Observational, performance improvement. Veterans Affairs outpatient endoscopy. Routine colonoscopy cases. Colonoscopy using air or water exchange method was performed as previously described. The MEI equipment (ScopeGuide, Olympus) with built-in magnetic sensors displays the configuration of the colonoscope inside the patient. During sedated colonoscopy the endoscopist was blinded to the ScopeGuide images which were recorded and subsequently reviewed. Loop formation based on a visual guide provided by Olympus. There were 41 and 32 cases in the water exchange and air group, respectively. The sigmoid N loop was most common, followed by the sigmoid alpha loop, and exaggeration of scope curvature at the splenic flexure/transverse colon. Of these, 20/32 vs. 9/41 patients (p=0.0007) had sigmoid looping, and 17/32 vs. 9/41 patients (p=0.0007) had sigmoid/splenic looping when the scope tip was in the transverse colon, in the air and water exchange group, respectively. Colonoscopy method was not blinded and non randomized. MEI data objectively demonstrated significantly fewer loops during water exchange colonoscopy, elucidating its mechanism of pain alleviation - attenuation of loop formation. Since MEI feedback enhances cecal intubation by trainees, the role of MEI combined water exchange in speeding up trainee learning curves deserves further evaluations.

  6. Spatial-temporal evolution of self-organized loop-patterns on a water surface and a diffuse discharge in the gap

    Science.gov (United States)

    Li, Xuechen; Geng, Jinling; Jia, Pengying; Zhang, Panpan; Zhang, Qi; Li, Yaru

    2017-11-01

    Excited by an alternating current voltage, a patterned discharge and a diffuse discharge are generated in a needle to liquid configuration. Using an intensified charge-coupled device (ICCD), temporal evolution of the discharge between the two electrodes is investigated for the diffuse mode and the patterned mode, respectively. For the diffuse mode, the positive discharge is in a glow regime, and the negative discharge is in a Townsend discharge regime. For the patterned mode, the discharge always belongs to the Townsend discharge regime. Moreover, in the patterned mode, various patterns including the single loop, single loop with the surrounding corona, triple loops, and concentric loops with a central spot are observed on the water surface with the increasing positive peak-value of the applied voltage (Upp). Temporally resolved images of the loop-patterns are captured on the water surface. From the electrical measurements and the ICCD imaging, it is found that the loop pattern emerges after the discharge bridges the two electrodes. Then, it begins to evolve and finally degenerates with the decrease in the discharge current. The pattern does not disappear until the discharge quenches. Formation of the loop-patterns is attributed to the role of negative ions.

  7. Efforts to Reduce International Space Station Crew Maintenance Time in the Management of the Extravehicular Mobility Unit Transport Loop Water Quality

    Science.gov (United States)

    Etter,David; Rector, Tony; Boyle, robert; Zande, Chris Vande

    2012-01-01

    The EMU (Extravehicular Mobility Unit) contains a semi-closed-loop re-circulating water circuit (Transport Loop) to absorb heat into a LCVG (Liquid Coolant and Ventilation Garment) worn by the astronaut. A second, single-pass water circuit (Feed-water Loop) provides water to a cooling device (Sublimator) containing porous plates, and that water sublimates through the porous plates to space vacuum. The cooling effect from the sublimation of this water translates to a cooling of the LCVG water that circulates through the Sublimator. The quality of the EMU Transport Loop water is maintained through the use of a water processing kit (ALCLR - Airlock Cooling Loop Remediation) that is used to periodically clean and disinfect the water circuit. Opportunities to reduce crew time associated with ALCLR operations include a detailed review of the historical water quality data for evidence to support an extension to the implementation cycle. Furthermore, an EMU returned after 2-years of use on the ISS (International Space Station) is being used as a test bed to evaluate the results of extended and repeated ALCLR implementation cycles. Finally, design, use and on-orbit location enhancements to the ALCLR kit components are being considered to allow the implementation cycle to occur in parallel with other EMU maintenance and check-out activities, and to extend the life of the ALCLR kit components. These efforts are undertaken to reduce the crew-time and logistics burdens for the EMU, while ensuring the long-term health of the EMU water circuits for a post- Shuttle 6-year service life.

  8. Three-dimensional inversion of CSEM data: Water leak detection using a small-loop EM method

    Science.gov (United States)

    Noh, Kyubo; Chung, Yonghyun; Seol, Soon Jee; Byun, Joongmoo; Uchida, Toshihiro

    2014-03-01

    Electromagnetic (EM) data sets were acquired using ground-based small-loop electromagnetic (EM) sensors over an artificially constructed sandy ground in Tsukuba, Japan, for three conditions of water saturation. The research aim was to evaluate the imaging capability of the geophysical method for detecting a water leak. Because the sensitivity analysis showed a considerable three-dimensional (3D) distribution of sensitivity around the source-receiver location, 3D inversion was applied to the field data sets. We used an accurate 3D controlled-source electromagnetic (CSEM) inversion algorithm, which adopted an edge-based finite element method as a forward scheme. To obtain the best inversion strategy for our field data and for the selection of the optimal regularization method, 3D inversion was applied to synthetic data sets prior to the inversion of the field data; the synthetic data sets were based on synthetic resistivity models used to simulate the three water-saturation phases of the real test site. Based on the results of sensitivity analysis, different regularization methods were systematically tested and the inversion results were qualitatively analyzed. For our monitoring scenario, the best performance was achieved by combining spatially varying regularization parameters, structural constraints, and the reference model method. The reference model parameters were derived from the less ill-posed model, instead of the main target model, which allowed for more accurate imaging of the main region of interest. This optimal inversion strategy was applied to the test-site field data. The water leak was successfully visualized by small-loop EM data, with systematic application of a priori information as constraints.

  9. Closing the loop: integrating human impacts on water resources to advanced land surface models

    Science.gov (United States)

    Zaitchik, B. F.; Nie, W.; Rodell, M.; Kumar, S.; Li, B.

    2016-12-01

    Advanced Land Surface Models (LSMs), including those used in the North American Land Data Assimilation System (NLDAS), offer a physically consistent and spatially and temporally complete analysis of the distributed water balance. These models are constrained both by physically-based process representation and by observations ingested as meteorological forcing or as data assimilation updates. As such, they have become important tools for hydrological monitoring and long-term climate analysis. The representation of water management, however, is extremely limited in these models. Recent advances have brought prognostic irrigation routines into models used in NLDAS, while assimilation of Gravity Recovery and Climate Experiment (GRACE) derived estimates of terrestrial water storage anomaly has made it possible to nudge models towards observed states in water storage below the root zone. But with few exceptions these LSMs do not account for the source of irrigation water, leading to a disconnect between the simulated water balance and the observed human impact on water resources. This inconsistency is unacceptable for long-term studies of climate change and human impact on water resources in North America. Here we define the modeling challenge, review instances of models that have begun to account for water withdrawals (e.g., CLM), and present ongoing efforts to improve representation of human impacts on water storage across models through integration of irrigation routines, water withdrawal information, and GRACE Data Assimilation in NLDAS LSMs.

  10. Rise time reduction of thermal actuators operated in air and water through optimized pre-shaped open-loop driving

    Science.gov (United States)

    Larsen, T.; Doll, J. C.; Loizeau, F.; Hosseini, N.; Peng, A. W.; Fantner, G. E.; Ricci, A. J.; Pruitt, B. L.

    2017-04-01

    Electrothermal actuators have many advantages compared to other actuators used in micro-electro-mechanical systems (MEMS). They are simple to design, easy to fabricate and provide large displacements at low voltages. Low voltages enable less stringent passivation requirements for operation in liquid. Despite these advantages, thermal actuation is typically limited to a few kHz bandwidth when using step inputs due to its intrinsic thermal time constant. However, the use of pre-shaped input signals offers a route for reducing the rise time of these actuators by orders of magnitude. We started with an electrothermally actuated cantilever having an initial 10-90% rise time of 85 μs in air and 234 μs in water for a standard open-loop step input. We experimentally characterized the linearity and frequency response of the cantilever when operated in air and water, allowing us to obtain transfer functions for the two cases. We used these transfer functions, along with functions describing desired reduced rise-time system responses, to numerically simulate the required input signals. Using these pre-shaped input signals, we improved the open-loop 10-90% rise time from 85 μs to 3 μs in air and from 234 μs to 5 μs in water, an improvement by a factor of 28 and 47, respectively. Using this simple control strategy for MEMS electrothermal actuators makes them an attractive alternative to other high speed micromechanical actuators such as piezoelectric stacks or electrostatic comb structures which are more complex to design, fabricate, or operate.

  11. Modeling the Impacts of the Loop Current on Circulation and Water Properties in Pulley Ridge Area, Southwest Florida Shelf

    Science.gov (United States)

    Pan, C.; Jiang, M.; Dalgleish, F.; Reed, J.

    2016-02-01

    A high resolution ( 1.5km) regional ocean model has been developed for the southern Florida Shelf and Florida Straits. Analysis of the model shows that the meandering of the Gulf of Mexico Loop Current exerts strong impacts on the circulation dynamics over the Pulley Ridge region on the southwestern Florida shelf, where the Loop Current (LC) turns east into Florida Straits to become Florida Current (FC). In particular, the northward migration of the LC/FC front tends to drive a strong onshelf (eastward) transport of the gulf water onto the southern Pulley Ridge, an important area where abundant photosynthetic corals can be found at depth between 60 and 90 m. Remotely or locally generated eddies over the western shelf slope of the Pulley Ridge can also be blocked by the northern LC/FC front when it is closely in contact with the shelf break. These eddies drive strong upwelling of slope water toward the shelf break and sometimes onto the shelf. In the southern Florida Straits, FC may also strongly interact with the shelf slope from the Dry Tortugas to the Florida Keys, often in association with the meandering of the Florida Current. Moreover, a significant return flow, largely within the upper 150 m, may be produced when the FC impinges upon the continental slope. The return flow may extend all the way from the contact point between the FC and shelf slope to the northwestern side of the Pulley Ridge, providing yet another mechanism for water exchange between the shelf and slope.

  12. Coral mucus fuels the sponge loop in warm- and cold-water coral reef ecosystems

    NARCIS (Netherlands)

    Rix, L.; de Goeij, J.M.; Mueller, C.E.; Struck, U.; Middelburg, J.J.; van Duyl, F.C.; Al-Horani, F.A.; Wild, C.; Naumann, M.S.; van Oevelen, D.

    2016-01-01

    Shallow warm-water and deep-sea cold-water corals engineer the coral reef framework and fertilize reef communities by releasing coral mucus, a source of reef dissolved organic matter (DOM). By transforming DOM into particulate detritus, sponges play a key role in transferring the energy and

  13. [Investigation on Toxoplasma gondii by polymerase chain reaction and loop-mediated isothermal amplification in water samples from Giresun, Turkey].

    Science.gov (United States)

    Demirel, Elif; Kolören, Zeynep; Karaman, Ulkü; Ayaz, Emine

    2014-10-01

    Toxoplasmosis is generally asymptomatic in immunocompetent subjects, however serious manifestations of the disease may develop in immunocompromised patients and in pregnant women. The mean Toxoplasma gondii seroprevalence which is approximately 40% in Turkish population, indicates the high risk for the development of acute toxoplasmosis in those cases. One of the transmission ways of T.gondii is the consumption of contaminated water. The aim of this study was to detect the presence of T.gondii in the environmental and drinking water samples by using standard polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP) methods. A total of 96 water samples, of them 76 were environmental water samples collected from creeks in Giresun province center and its various districts (Piraziz, Bulancak, Keşap, Espiye) and 20 from drinking water samples, were included in the study. The samples were precipitated by the aluminium sulfate method and DNAs were isolated from the pellets formed with the sucrose gradient method. PCR and LAMP were applied to the isolated DNAs, by the use of primers F3 and B3 specific to B1 gene of the parasite. In our study, T.gondii was detected in none of the drinking water samples by PCR and LAMP, however T.gondii DNAs were positive in 13.2% (10/76) of the environmental water samples. Both of the methods yielded the same results in those samples. The stations that were positive for T.gondii were Aksu creek in Giresun province center; Gelivera creek in Espiye; Yolağzı, Keşap, Keşap Login Bridge creeks in Keşap; Bulancak, Karadere and İncivez creeks in Bulancak; Piraziz and Çayırağzı creeks in Piraziz counties. Resistance of T.gondii to chlorination and the inadequacy of the filtration processes, create a serious threat among people in contact with rivers, sea and drinking waters particularly in areas with high humidity. As far as the national literature was considered, no report about the water-borne T

  14. ENERGY AND ENVIRONMENTAL ANALYSIS OF AN OPEN-LOOP GROUND-WATER HEAT PUMP SYSTEM IN AN URBAN AREA

    Directory of Open Access Journals (Sweden)

    Giorgia Baccino

    2010-01-01

    Full Text Available In this paper a multidisciplinary methodology for analyzing the opportunities for exploitation of open-loop groundwater heat pump is proposed. The approach starts from a model for calculation of a time profile of thermal requirements (heat and domestic hot water. This curve is then coupled with a model of the control system in order to determine the heat pump operation, which includes its energy performances (primary energy consumption as well as profiles of water discharge to the aquifer in terms of mass flow rate and temperature. Then the thermo-fluid dynamics of the aquifer is performed in order to determine the system impact on the environment as on possible other systems. The application to a case study in the Piedmont region, in Italy, is proposed. Energy analysis of the system shows that ground-water heat pumps constitute an interesting option in areas with small housing density, where there is not district heating. In comparison with typical heating/cooling systems, environmental benefits are related with reduction in global emissions. These benefits may be significantly enhanced using renewables as the primary energy source to produce electricity. The analysis also shows that possible issues related with the extension of the subsurface thermal plume may arise in the case of massive utilization of this technology.

  15. Preliminary Feasibility, Design, and Hazard Analysis of a Boiling Water Test Loop Within the Idaho National Laboratory Advanced Test Reactor National Scientific User Facility

    Energy Technology Data Exchange (ETDEWEB)

    Douglas M. Gerstner

    2009-05-01

    The Advanced Test Reactor (ATR) is a pressurized light-water reactor with a design thermal power of 250 MW. The principal function of the ATR is to provide a high neutron flux for testing reactor fuels and other materials. The ATR and its support facilities are located at the Idaho National Laboratory (INL). A Boiling Water Test Loop (BWTL) is being designed for one of the irradiation test positions within the. The objective of the new loop will be to simulate boiling water reactor (BWR) conditions to support clad corrosion and related reactor material testing. Further it will accommodate power ramping tests of candidate high burn-up fuels and fuel pins/rods for the commercial BWR utilities. The BWTL will be much like the pressurized water loops already in service in 5 of the 9 “flux traps” (region of enhanced neutron flux) in the ATR. The loop coolant will be isolated from the primary coolant system so that the loop’s temperature, pressure, flow rate, and water chemistry can be independently controlled. This paper presents the proposed general design of the in-core and auxiliary BWTL systems; the preliminary results of the neutronics and thermal hydraulics analyses; and the preliminary hazard analysis for safe normal and transient BWTL and ATR operation.

  16. Experimental study of thermo-hydraulic characteristics of natural circulation loop at water and FC-72 boiling under atmospheric pressure

    Science.gov (United States)

    Kaban’kov, O. N.; Sukomel, L. A.; Zubov, N. O.; Yagov, V. V.

    2017-10-01

    The results of experimental study of thermo and hydraulic characteristics of flow boiling of water and FC-72 in natural circulation loop under atmospheric pressure are presented. The experimental data have been obtained in the range of wall heat flux densities (6 – 70) kW/m2 for water and (4.6 – 30) kW/m2 for FC-72. These two liquids differ substantially in thermophysical properties so it makes it possible to extend the range of reduced pressures almost for an order of magnitude without changing the technical parameters of experimental setup. An additional information for the analysis of flow pattern influence on onset of instability and unstable circulation mechanism have been obtained as the result. The flow up tube of the loop had inner diameter 9.1 mm and consisted of two section – heated one 98 diameters length (that is 65 % of total tube length) and upper adiabatic section with length 48 diameters. Different circulation regimes were realized in experiments: mixed regimes with single phase and boiling zones in the heated part of the tube and boiling regimes along the full length of the heated section. The experimental data on circulation velocity (flow rate) and wall temperature distributions (including pulsating components of temperature and velocity) are presented in dependence on wall heat flux density and liquid subcooling at the inlet to the heated zone. At water experiments autooscillating regimes of boiling flows were observed within the whole range of inlet liquid subcoolings up to saturation temperature and at all wall heat flux densities from lowest one (10 kW/m2) to somewhat upper limiting value of 64 kW/m2. At higher heat fluxes the two-phase boiling flow was stable not only in saturation inlet liquid temperature but also at low subcoolings. In FC-72 experiments the flow was stable at all realized heat flux densities within the range of inlet liquid subcoolings (2 – 20) °C.

  17. Effect of Spray System on Fission Product Distribution in Containment During a Severe Accident in a Two-Loop Pressurized Water Reactor

    National Research Council Canada - National Science Library

    Dehjourian, Mehdi; Rahgoshay, Mohammad; Sayareh, Reza; Jahanfarnia, Gholamreza; Shirani, Amir Saied

    2016-01-01

    The containment response during the first 24 hours of a low-pressure severe accident scenario in a nuclear power plant with a two-loop Westinghouse-type pressurized water reactor was simulated with the CONTAIN 2.0 computer code...

  18. Multi-loop social learning for sustainable land and water governance: Towards a research agenda on the potential of virtual learning platforms

    NARCIS (Netherlands)

    Medema, W.J.; Wals, A.E.J.; Adamowski, J.

    2014-01-01

    Managing social-ecological systems and human well being in a sustainable way requires knowledge of these systems in their full complexity. Multi-loop social learning is recognized as a crucial element to sustainable decision-making for land and water resources management involving a process of

  19. Reduced-scale water test of natural circulation for decay heat removal in loop-type sodium-cooled fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, T., E-mail: murakami@criepi.denken.or.jp [Central Research Institute of Electric Power Industry, 1646 Abiko, Chiba (Japan); Eguchi, Y., E-mail: eguchi@criepi.denken.or.jp [Central Research Institute of Electric Power Industry, 1646 Abiko, Chiba (Japan); Oyama, K., E-mail: kazuhiro_oyama@mfbr.mhi.co.jp [Mitsubishi FBR Systems, Inc., 2-34-17 Jinguumae, Shibuya, Tokyo (Japan); Watanabe, O., E-mail: osamu4_watanabe@mfbr.mhi.co.jp [Mitsubishi FBR Systems, Inc., 2-34-17 Jinguumae, Shibuya, Tokyo (Japan)

    2015-07-15

    Highlights: • The natural circulation characteristics of a loop-type SFR are examined by a water test. • The performance of decay heat removal system is evaluated using a similarity law. • The effects of flow deviation in the parallel piping of a primary loop are clarified. • The reproducibility of the natural circulation test is confirmed. - Abstract: Water tests of a loop-type sodium-cooled fast reactor have been conducted to physically evaluate the natural circulation characteristics. The water test apparatus was manufactured as a 1/10-scale mock-up of the Japan Sodium-Cooled Fast Reactor, which adopts a decay heat removal system (DHRS) utilizing natural circulation. Tests simulating a variety of events and operation conditions clarified the thermal hydraulic characteristics and core-cooling performance of the natural circulation in the primary loop. Operation conditions such as the duration of the pump flow coast-down and the activation time of the DHRS affect the natural circulation characteristics. A long pump flow coast-down cools the upper plenum of the reactor vessel (RV). This causes the loss of the buoyant force in the RV. The test result indicates that a long pump flow coast-down tends to result in a rapid increase in the core temperature because of the loss of the buoyant force. The delayed activation of the DHRS causes a decrease in the natural circulation flow rate and a temperature rise in the RV. Flow rate deviation and a reverse flow appear in the parallel cold-leg piping in some events, which cause thermal stratification in the cold-leg piping. The DHRS prevents the core temperature from fatally rise even for the most severe design-basis event, in which sodium leakage in a secondary loop of the DHRS and the opening failure of a single damper of the air cooler occur simultaneously. In the water test for the case of siphon break in the primary loop, which is one of the design extension conditions, a circulation flow consisting of ascendant

  20. Dynamic Modeling of Process Technologies for Closed-Loop Water Recovery Systems

    Science.gov (United States)

    Allada, Rama Kumar; Lange, Kevin E.; Anderson, Molly S.

    2012-01-01

    Detailed chemical process simulations are a useful tool in designing and optimizing complex systems and architectures for human life support. Dynamic and steady-state models of these systems help contrast the interactions of various operating parameters and hardware designs, which become extremely useful in trade-study analyses. NASA s Exploration Life Support technology development project recently made use of such models to compliment a series of tests on different waste water distillation systems. This paper presents dynamic simulations of chemical process for primary processor technologies including: the Cascade Distillation System (CDS), the Vapor Compression Distillation (VCD) system, the Wiped-Film Rotating Disk (WFRD), and post-distillation water polishing processes such as the Volatiles Removal Assembly (VRA). These dynamic models were developed using the Aspen Custom Modeler (Registered TradeMark) and Aspen Plus(Registered TradeMark) process simulation tools. The results expand upon previous work for water recovery technology models and emphasize dynamic process modeling and results. The paper discusses system design, modeling details, and model results for each technology and presents some comparisons between the model results and available test data. Following these initial comparisons, some general conclusions and forward work are discussed.

  1. Modeling a direct contact heat exchanger for a supercritical water loop

    Energy Technology Data Exchange (ETDEWEB)

    Cascella, F.; Teyssedou, A., E-mail: alberto.teyssedou@polymtl.ca [Ecole Polytechnique de Montreal, Montreal, Quebec (Canada)

    2013-07-01

    In the last thirty years, Direct Contact Heat Exchangers (DCHX) have found a great success in different power engineering applications. In fact, due to the direct contact of hot and cold working fluids, it is possible to reach very high mass and energy transfer efficiencies. Despite their high performance, it is still quite difficult to predict the correct heat transfer as a function of plant operation conditions, which constitutes a fundamental parameter to correctly operate heat exchangers. Therefore, in this work, a DCHX used in the Thermo-Hydraulic Laboratory of Ecole Polytechnique de Montreal, has been studied. It consists of a vessel where superheated steam is cooled by mixing it with sub-cooled water via a nozzle that sprays the water under the form of tiny droplets (i.e., of about 200 μm in diameter). A thermodynamic model that takes into account the statistical distribution of droplets and their temperature evolution is developed. To this aim, the Droplet Distribution Function (DDF) based on Rosin-Rammler's equation is used. In the proposed model, the thermal energy exchange between liquid and steam takes into account both convection and evaporation heat transfer mechanisms. A comparison of model's predictions with experimental data shows very good agreement for steam pressures of 1.6 and 2.1 MPa, however at higher pressures the model over predicts the experimental trends. (author)

  2. Detailed Modeling of Distillation Technologies for Closed-Loop Water Recovery Systems

    Science.gov (United States)

    Allada, Rama Kumar; Lange, Kevin E.; Anderson, Molly S.

    2011-01-01

    Detailed chemical process simulations are a useful tool in designing and optimizing complex systems and architectures for human life support. Dynamic and steady-state models of these systems help contrast the interactions of various operating parameters and hardware designs, which become extremely useful in trade-study analyses. NASA?s Exploration Life Support technology development project recently made use of such models to compliment a series of tests on different waste water distillation systems. This paper presents efforts to develop chemical process simulations for three technologies: the Cascade Distillation System (CDS), the Vapor Compression Distillation (VCD) system and the Wiped-Film Rotating Disk (WFRD) using the Aspen Custom Modeler and Aspen Plus process simulation tools. The paper discusses system design, modeling details, and modeling results for each technology and presents some comparisons between the model results and recent test data. Following these initial comparisons, some general conclusions and forward work are discussed.

  3. Putting humans in the loop: Using crowdsourced snow information to inform water management

    Science.gov (United States)

    Fedorov, Roman; Giuliani, Matteo; Castelletti, Andrea; Fraternali, Piero

    2016-04-01

    The unprecedented availability of user generated data on the Web due to the advent of online services, social networks, and crowdsourcing, is opening new opportunities for enhancing real-time monitoring and modeling of environmental systems based on data that are public, low-cost, and spatio-temporally dense, possibly contributing to our ability of making better decisions. In this work, we contribute a novel crowdsourcing procedure for computing virtual snow indexes from public web images, either produced by users or generated by touristic webcams, which is based on a complex architecture designed for automatically crawling content from multiple web data sources. The procedure retains only geo-tagged images containing a mountain skyline, identifies the visible peaks in each image using a public online digital terrain model, and classifies the mountain image pixels as snow or no-snow. This operation yields a snow mask per image, from which it is possible to extract time series of virtual snow indexes representing a proxy of the snow covered area. The value of the obtained virtual snow indexes is estimated in a real world water management problem. We consider the snow-dominated catchment of Lake Como, a regulated lake in Northern Italy, where snowmelt represents the most important contribution to seasonal lake storage, and we used the virtual snow indexes for informing the daily operation of the lake's dam. Numerical results show that such information is effective in extending the anticipation capacity of the lake operations, ultimately improving the system performance.

  4. Experimental investigation on thermal performance of a closed loop pulsating heat pipe (CLPHP) using methanol and distilled water at different filling ratios

    Science.gov (United States)

    Rahman, Md. Lutfor; Swarna, Anindita Dhar; Ahmed, Syed Nasif Uddin; Perven, Sanjida; Ali, Mohammad

    2016-07-01

    Pulsating Heat Pipes, the new two-phase heat transfer devices, with no counter current flow between liquid and vapor have become a modern topic for research in the field of thermal management. This paper focuses on the performance of methanol and distilled water as working fluid in a closed loop pulsating heat pipe (CLPHP). This performances are compared in terms of thermal resistance, heat transfer co-efficient, and evaporator and condenser wall temperature with variable heat inputs. Methanol and Distilled water are selected for their lower surface tension, dynamic viscosity and sensible heat. A closed loop PHP made of copper with 2mm ID and 2.5mm OD having total 8 loops are supplied with power input varied from 10W to 60W. During the experiment the PHP is kept vertical, while the filling ratio (FR) is increased gradually from 40% to 70% with 10% increment. The optimum filling ratio for a minimum thermal resistance is found to be 60% and 40% for distilled water and methanol respectively and methanol is found to be the better working fluid compared to distilled water in terms of its lower thermal resistance and higher heat transfer coefficient.

  5. Experimental Study on Hydrate Induction Time of Gas-Saturated Water-in-Oil Emulsion using a High-Pressure Flow Loop

    Directory of Open Access Journals (Sweden)

    Lv X.F.

    2015-11-01

    Full Text Available Hydrate is one of the critical precipitates which have to be controlled for subsea flow assurance. The induction time of hydrate is therefore a significant parameter. However, there have been few studies on the induction time of the natural gas hydrate formation in a flow loop system. Consequently, a series of experiments were firstly performed, including water, natural gas and Diesel oil, on the hydrate induction time under various conditions such as the supercooling and supersaturation degree, water cut, anti-agglomerant dosage, etc. The experiments were conducted in a high-pressure hydrate flow loop newly constructed in the China University of Petroleum (Beijing, and dedicated to flow assurance studies. Then, based on previous research, this study puts forward a method for induction time, which is characterized by clear definition, convenient measurement and good generality. Furthermore, we investigated the influences of the experimental parameters and analyzed the experimental phenomena for the hydrate induction time in a flowing system.

  6. Effect of using acetone and distilled water on the performance of open loop pulsating heat pipe (OLPHP) with different filling ratios

    Science.gov (United States)

    Rahman, Md. Lutfor; Afrose, Tonima; Tahmina, Halima Khatun; Rinky, Rumana Parvin; Ali, Mohammad

    2016-07-01

    Pulsating heat pipe (PHP) is a new innovation in the modern era of miniaturizes thermal management system for its higher heating and cooling capacity. The objective of this experiment is to observe the performance of open loop pulsating heat pipe using two fluids at different filling ratios. This OLPHP is a copper capillary tube of 2.5mm outer diameter and 2mm inner diameter. It consists of 8 loops where the evaporative section is 50mm, adiabatic section is 120mm and condensation section is 80mm. The experiment is conducted with distilled water and acetone at 40%, 50%, 60%, and 70% filling ratios where 0° (vertical) is considered as definite angle of inclination. Distilled water and acetone are selected as working fluids considering their different latent heat of vaporization and surface tension. It is found that acetone shows lower thermal resistance than water at all heat inputs. Best performance of acetone is attained at 70% filling ratio. Water displays better heat transfer capability at 50% filling ratio.

  7. Loop-to-loop coupling.

    Energy Technology Data Exchange (ETDEWEB)

    Warne, Larry Kevin; Lucero, Larry Martin; Langston, William L.; Salazar, Robert Austin; Coleman, Phillip Dale; Basilio, Lorena I.; Bacon, Larry Donald

    2012-05-01

    This report estimates inductively-coupled energy to a low-impedance load in a loop-to-loop arrangement. Both analytical models and full-wave numerical simulations are used and the resulting fields, coupled powers and energies are compared. The energies are simply estimated from the coupled powers through approximations to the energy theorem. The transmitter loop is taken to be either a circular geometry or a rectangular-loop (stripline-type) geometry that was used in an experimental setup. Simple magnetic field models are constructed and used to estimate the mutual inductance to the receiving loop, which is taken to be circular with one or several turns. Circuit elements are estimated and used to determine the coupled current and power (an equivalent antenna picture is also given). These results are compared to an electromagnetic simulation of the transmitter geometry. Simple approximate relations are also given to estimate coupled energy from the power. The effect of additional loads in the form of attached leads, forming transmission lines, are considered. The results are summarized in a set of susceptibility-type curves. Finally, we also consider drives to the cables themselves and the resulting common-to-differential mode currents in the load.

  8. Effect of Spray System on Fission Product Distribution in Containment During a Severe Accident in a Two-Loop Pressurized Water Reactor

    Directory of Open Access Journals (Sweden)

    Mehdi Dehjourian

    2016-08-01

    Full Text Available The containment response during the first 24 hours of a low-pressure severe accident scenario in a nuclear power plant with a two-loop Westinghouse-type pressurized water reactor was simulated with the CONTAIN 2.0 computer code. The accident considered in this study is a large-break loss-of-coolant accident, which is not successfully mitigated by the action of safety systems. The analysis includes pressure and temperature responses, as well as investigation into the influence of spray on the retention of fission products and the prevention of hydrogen combustion in the containment.

  9. Effect of pH on the concentrations of lead and trace contaminants in drinking water: a combined batch, pipe loop and sentinel home study.

    Science.gov (United States)

    Kim, Eun Jung; Herrera, Jose E; Huggins, Dan; Braam, John; Koshowski, Scott

    2011-04-01

    High lead levels in drinking water are still a concern for households serviced by lead pipes in many parts of North America and Europe. This contribution focuses on the effect of pH on lead concentrations in drinking water delivered through lead pipes. Though this has been addressed in the past, we have conducted a combined batch, pipe loop and sentinel study aiming at filling some of the gaps present in the literature. Exhumed lead pipes and water quality data from the City of London's water distribution system were used in this study. As expected, the lead solubility of corrosion scale generally decreased as pH increased; whereas dissolution of other accumulated metals present in the corrosion scale followed a variety of trends. Moreover, dissolved arsenic and aluminum concentrations showed a strong correlation, indicating that the aluminosilicate phase present in the scale accumulates arsenic. A significant fraction of the total lead concentration in water was traced to particulate lead. Our results indicate that particulate lead is the primary contributor to total lead concentration in flowing systems, whereas particulate lead contribution to total lead concentrations for stagnated systems becomes significant only at high water pH values. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Development of a rapid, simple method for detecting Naegleria fowleri visually in water samples by loop-mediated isothermal amplification (LAMP.

    Directory of Open Access Journals (Sweden)

    Aongart Mahittikorn

    Full Text Available Naegleria fowleri is the causative agent of the fatal disease primary amebic meningoencephalitis. Detection of N. fowleri using conventional culture and biochemical-based assays is time-consuming and laborious, while molecular techniques, such as PCR, require laboratory skills and expensive equipment. We developed and evaluated a novel loop-mediated isothermal amplification (LAMP assay targeting the virulence-related gene for N. fowleri. Time to results is about 90 min and amplification products were easily detected visually using hydroxy naphthol blue. The LAMP was highly specific after testing against related microorganisms and able to detect one trophozoite, as determined with spiked water and cerebrospinal fluid samples. The assay was then evaluated with a set of 80 water samples collected during the flooding crisis in Thailand in 2011, and 30 natural water samples from border areas of northern, eastern, western, and southern Thailand. N. fowleri was detected in 13 and 10 samples using LAMP and PCR, respectively, with a Kappa coefficient of 0.855. To the best of our knowledge, this is the first report of a LAMP assay for N. fowleri. Due to its simplicity, speed, and high sensitivity, the LAMP method described here might be useful for quickly detecting and diagnosing N. fowleri in water and clinical samples, particularly in resource-poor settings.

  11. Development of a rapid, simple method for detecting Naegleria fowleri visually in water samples by loop-mediated isothermal amplification (LAMP).

    Science.gov (United States)

    Mahittikorn, Aongart; Mori, Hirotake; Popruk, Supaluk; Roobthaisong, Amonrattana; Sutthikornchai, Chantira; Koompapong, Khuanchai; Siri, Sukhontha; Sukthana, Yaowalark; Nacapunchai, Duangporn

    2015-01-01

    Naegleria fowleri is the causative agent of the fatal disease primary amebic meningoencephalitis. Detection of N. fowleri using conventional culture and biochemical-based assays is time-consuming and laborious, while molecular techniques, such as PCR, require laboratory skills and expensive equipment. We developed and evaluated a novel loop-mediated isothermal amplification (LAMP) assay targeting the virulence-related gene for N. fowleri. Time to results is about 90 min and amplification products were easily detected visually using hydroxy naphthol blue. The LAMP was highly specific after testing against related microorganisms and able to detect one trophozoite, as determined with spiked water and cerebrospinal fluid samples. The assay was then evaluated with a set of 80 water samples collected during the flooding crisis in Thailand in 2011, and 30 natural water samples from border areas of northern, eastern, western, and southern Thailand. N. fowleri was detected in 13 and 10 samples using LAMP and PCR, respectively, with a Kappa coefficient of 0.855. To the best of our knowledge, this is the first report of a LAMP assay for N. fowleri. Due to its simplicity, speed, and high sensitivity, the LAMP method described here might be useful for quickly detecting and diagnosing N. fowleri in water and clinical samples, particularly in resource-poor settings.

  12. A Closed Loop System Using a Brine Reservoir to Replace Fresh Water as the Frac Fluid Source

    Science.gov (United States)

    A non-fresh water source, the Debolt formation, has been proposed and tested in the laboratory and field for application as a fracturing fluid in shale gas formations, with potential to replace much of the fresh water used in the Horn River Basin.

  13. Pneumatic control loops save water and energy with fixed-bed filters; Pneumatische Steuerkreise sparen Wasser und Energie bei Festbettfiltern

    Energy Technology Data Exchange (ETDEWEB)

    Rieger, Wolfgang [Festo AG und Co. KG, Esslingen (Germany)

    2010-09-15

    Handwheel control or an automated shut-off valve? The trend world-wide is clearly towards automation. Automation saves energy and water, particularly flushing water, and increases operational reliability. This is illustrated, for example, by the pneumatic automation of fixed-bed filters in a waterworks. (orig.)

  14. System-Level Heat Transfer Analysis, Thermal- Mechanical Cyclic Stress Analysis, and Environmental Fatigue Modeling of a Two-Loop Pressurized Water Reactor. A Preliminary Study

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish [Argonne National Lab. (ANL), Argonne, IL (United States); Soppet, William [Argonne National Lab. (ANL), Argonne, IL (United States); Majumdar, Saurin [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, Ken [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-01-03

    This report provides an update on an assessment of environmentally assisted fatigue for light water reactor components under extended service conditions. This report is a deliverable in April 2015 under the work package for environmentally assisted fatigue under DOE's Light Water Reactor Sustainability program. In this report, updates are discussed related to a system level preliminary finite element model of a two-loop pressurized water reactor (PWR). Based on this model, system-level heat transfer analysis and subsequent thermal-mechanical stress analysis were performed for typical design-basis thermal-mechanical fatigue cycles. The in-air fatigue lives of components, such as the hot and cold legs, were estimated on the basis of stress analysis results, ASME in-air fatigue life estimation criteria, and fatigue design curves. Furthermore, environmental correction factors and associated PWR environment fatigue lives for the hot and cold legs were estimated by using estimated stress and strain histories and the approach described in NUREG-6909. The discussed models and results are very preliminary. Further advancement of the discussed model is required for more accurate life prediction of reactor components. This report only presents the work related to finite element modelling activities. However, in between multiple tensile and fatigue tests were conducted. The related experimental results will be presented in the year-end report.

  15. Alternative loop rings

    CERN Document Server

    Goodaire, EG; Polcino Milies, C

    1996-01-01

    For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

  16. Defluoridation of drinking water by electrocoagulation/electroflotation in a stirred tank reactor with a comparative performance to an external-loop airlift reactor

    Energy Technology Data Exchange (ETDEWEB)

    Essadki, A.H., E-mail: essadki@hotmail.com [Ecole Superieure de Technologie de Casablanca, BP 8012, Oasis, Casablanca (Morocco); Gourich, B. [Ecole Superieure de Technologie de Casablanca, BP 8012, Oasis, Casablanca (Morocco); Vial, Ch. [Laboratoire de Genie Chimique et Biochimique, LGCB-UBP/ENSCCF, 24 avenue des Landais, BP 206, 63174 Aubiere Cedex (France); Delmas, H. [Laboratoire de Genie Chimique, ENSIACET-INPT, 5 rue Paulin Talabot, 31106 Toulouse (France); Bennajah, M. [Ecole Superieure de Technologie de Casablanca, BP 8012, Oasis, Casablanca (Morocco); Laboratoire de Genie Chimique, ENSIACET-INPT, 5 rue Paulin Talabot, 31106 Toulouse (France)

    2009-09-15

    Defluoridation using batch electrocoagulation/electroflotation (EC/EF) was carried out in two reactors for comparison purpose: a stirred tank reactor (STR) close to a conventional EC cell and an external-loop airlift reactor (ELAR) that was recently described as an innovative reactor for EC. The respective influences of current density, initial concentration and initial pH on the efficiency of defluoridation were investigated. The same trends were observed in both reactors, but the efficiency was higher in the STR at the beginning of the electrolysis, whereas similar values were usually achieved after 15 min operation. The influence of the initial pH was explained using the analyses of sludge composition and residual soluble aluminum species in the effluents, and it was related to the prevailing mechanisms of defluoridation. Fluoride removal and sludge reduction were both favored by an initial pH around 4, but this value required an additional pre-treatment for pH adjustment. Finally, electric energy consumption was similar in both reactors when current density was lower than 12 mA/cm{sup 2}, but mixing and complete flotation of the pollutants were achieved without additional mechanical power in the ELAR, using only the overall liquid recirculation induced by H{sub 2} microbubbles generated by water electrolysis, which makes subsequent treatments easier to carry out.

  17. Defluoridation of drinking water by electrocoagulation/electroflotation in a stirred tank reactor with a comparative performance to an external-loop airlift reactor.

    Science.gov (United States)

    Essadki, A H; Gourich, B; Vial, Ch; Delmas, H; Bennajah, M

    2009-09-15

    Defluoridation using batch electrocoagulation/electroflotation (EC/EF) was carried out in two reactors for comparison purpose: a stirred tank reactor (STR) close to a conventional EC cell and an external-loop airlift reactor (ELAR) that was recently described as an innovative reactor for EC. The respective influences of current density, initial concentration and initial pH on the efficiency of defluoridation were investigated. The same trends were observed in both reactors, but the efficiency was higher in the STR at the beginning of the electrolysis, whereas similar values were usually achieved after 15min operation. The influence of the initial pH was explained using the analyses of sludge composition and residual soluble aluminum species in the effluents, and it was related to the prevailing mechanisms of defluoridation. Fluoride removal and sludge reduction were both favored by an initial pH around 4, but this value required an additional pre-treatment for pH adjustment. Finally, electric energy consumption was similar in both reactors when current density was lower than 12mA/cm(2), but mixing and complete flotation of the pollutants were achieved without additional mechanical power in the ELAR, using only the overall liquid recirculation induced by H(2) microbubbles generated by water electrolysis, which makes subsequent treatments easier to carry out.

  18. Ontogenetic loops in habitat use highlight the importance of littoral habitats for early life-stages of oceanic fishes in temperate waters.

    Science.gov (United States)

    Polte, Patrick; Kotterba, Paul; Moll, Dorothee; von Nordheim, Lena

    2017-02-16

    General concepts of larval fish ecology in temperate oceans predominantly associate dispersal and survival to exogenous mechanisms such as passive drift along ocean currents. However, for tropical reef fish larvae and species in inland freshwater systems behavioural aspects of habitat selection are evidently important components of dispersal. This study is focused on larval Atlantic herring (Clupea harengus) distribution in a Baltic Sea retention area, free of lunar tides and directed current regimes, considered as a natural mesocosm. A Lorenz curve originally applied in socio-economics to describe demographic income distribution was adapted to a 20 year time-series of weekly larval herring distribution, revealing size-dependent spatial homogeneity. Additional quantitative sampling of distinct larval development stages across pelagic and littoral areas uncovered a loop in habitat use during larval ontogeny, revealing a key role of shallow littoral waters. With increasing rates of coastal change, our findings emphasize the importance of the littoral zone when considering reproduction of pelagic, ocean-going fish species; highlighting a need for more sensitive management of regional coastal zones.

  19. Ontogenetic loops in habitat use highlight the importance of littoral habitats for early life-stages of oceanic fishes in temperate waters

    Science.gov (United States)

    Polte, Patrick; Kotterba, Paul; Moll, Dorothee; von Nordheim, Lena

    2017-02-01

    General concepts of larval fish ecology in temperate oceans predominantly associate dispersal and survival to exogenous mechanisms such as passive drift along ocean currents. However, for tropical reef fish larvae and species in inland freshwater systems behavioural aspects of habitat selection are evidently important components of dispersal. This study is focused on larval Atlantic herring (Clupea harengus) distribution in a Baltic Sea retention area, free of lunar tides and directed current regimes, considered as a natural mesocosm. A Lorenz curve originally applied in socio-economics to describe demographic income distribution was adapted to a 20 year time-series of weekly larval herring distribution, revealing size-dependent spatial homogeneity. Additional quantitative sampling of distinct larval development stages across pelagic and littoral areas uncovered a loop in habitat use during larval ontogeny, revealing a key role of shallow littoral waters. With increasing rates of coastal change, our findings emphasize the importance of the littoral zone when considering reproduction of pelagic, ocean-going fish species; highlighting a need for more sensitive management of regional coastal zones.

  20. Verification of RELAP5-3D code in natural circulation loop as function of the initial water inventory

    Science.gov (United States)

    Bertani, C.; Falcone, N.; Bersano, A.; Caramello, M.; Matsushita, T.; De Salve, M.; Panella, B.

    2017-11-01

    High safety and reliability of advanced nuclear reactors, Generation IV and Small Modular Reactors (SMR), have a crucial role in the acceptance of these new plants design. Among all the possible safety systems, particular efforts are dedicated to the study of passive systems because they rely on simple physical principles like natural circulation, without the need of external energy source to operate. Taking inspiration from the second Decay Heat Removal system (DHR2) of ALFRED, the European Generation IV demonstrator of the fast lead cooled reactor, an experimental facility has been built at the Energy Department of Politecnico di Torino (PROPHET facility) to study single and two-phase flow natural circulation. The facility behavior is simulated using the thermal-hydraulic system code RELAP5-3D, which is widely used in nuclear applications. In this paper, the effect of the initial water inventory on natural circulation is analyzed. The experimental time behaviors of temperatures and pressures are analyzed. The experimental matrix ranges between 69 % and 93%; the influence of the opposite effects related to the increase of the volume available for the expansion and the pressure raise due to phase change is discussed. Simulations of the experimental tests are carried out by using a 1D model at constant heat power and fixed liquid and air mass; the code predictions are compared with experimental results. Two typical responses are observed: subcooled or two phase saturated circulation. The steady state pressure is a strong function of liquid and air mass inventory. The numerical results show that, at low initial liquid mass inventory, the natural circulation is not stable but pulsated.

  1. Modeling the impacts of the Loop Current on circulation and water properties over the Pulley Ridge region on the Southwest Florida shelf

    Science.gov (United States)

    Pan, Chudong; Jiang, Mingshun; Dalgleish, Fraser R.; Reed, John K.

    2017-04-01

    A high-resolution (∼1.5 km) regional ocean model was developed for the southern Florida Shelf and Florida Straits. A two-year (2011-12) simulation was conducted and the model results were generally in good agreement with available satellite and in situ data. Model results show that the meandering of the Gulf of Mexico Loop Current (LC) exerts strong impacts on the dynamics over Pulley Ridge on the southwest Florida shelf, where the LC turns into the Florida Straits to become the Florida Current (FC). In particular, the northward migration of the LC/FC front often drives strong on-shelf (eastward) transport of the slope water onto the shelf of southern Pulley Ridge, an important mesophotic coral reef at depths between 60 and 90 m. Frequent remotely or locally generated eddies over the western slope of Pulley Ridge may be blocked by the northern LC/FC front when it is closely in contact with the shelf break, a phenomenon documented in previous studies. These eddies drive strong upwelling of slope water toward the shelf break, which sometimes can extend 20-30 km onto the shelf, strongly affecting the Pulley Ridge region. A narrow return flow, largely along the shelf edge from Florida Keys to Pulley Ridge, may be produced when the FC impinges upon the continental slope during late fall to early spring. The results from an experiment without the surface winds suggest that wind forcing contributes to the westward flow but is not the determining factor for its generation.

  2. A model of film deformation and rupture under the action of thermo-capillary forces

    NARCIS (Netherlands)

    V. Pukhnachev; S. Dubinkina (Svetlana)

    2006-01-01

    htmlabstractA model of the deformation of a free weightless liquid film with rims fixed at a plane contour and subject to the action of thermocapillary forces is investigated. The film free-surface temperature is assumed to be a known function of the coordinates and time. The equation describing the

  3. Approximate Loop Unrolling

    OpenAIRE

    Rodriguez-Cancio, Marcelino; Combemale, Benoit; Baudry, Benoit

    2016-01-01

    We introduce Approximate Unrolling, a loop optimization that reduces execution time and energy consumption, exploiting the existence of code regions that can endure some degree of approximation while still producing acceptable results. This work focuses on a specific kind of forgiving region: counted loops that map a given functions over the elements of an array. Approximate Unrolling transforms loops in a similar way Loop Unrolling does. However, unlike its exact counterpart, our optimizatio...

  4. Blind Loop Syndrome

    Science.gov (United States)

    ... breeding ground for bacteria. The bacteria may produce toxins as well as block the absorption of nutrients. The greater the length of small bowel involved in the blind loop, the greater the chance of bacterial overgrowth. What triggers blind loop syndrome? Blind loop ...

  5. Tensile and Fatigue Testing and Material Hardening Model Development for 508 LAS Base Metal and 316 SS Similar Metal Weld under In-air and PWR Primary Loop Water Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish [Argonne National Lab. (ANL), Argonne, IL (United States); Soppet, William [Argonne National Lab. (ANL), Argonne, IL (United States); Majumdar, Saurin [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, Ken [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-01

    This report provides an update on an assessment of environmentally assisted fatigue for light water reactor components under extended service conditions. This report is a deliverable in September 2015 under the work package for environmentally assisted fatigue under DOE’s Light Water Reactor Sustainability program. In an April 2015 report we presented a baseline mechanistic finite element model of a two-loop pressurized water reactor (PWR) for systemlevel heat transfer analysis and subsequent thermal-mechanical stress analysis and fatigue life estimation under reactor thermal-mechanical cycles. In the present report, we provide tensile and fatigue test data for 508 low-alloy steel (LAS) base metal, 508 LAS heat-affected zone metal in 508 LAS–316 stainless steel (SS) dissimilar metal welds, and 316 SS-316 SS similar metal welds. The test was conducted under different conditions such as in air at room temperature, in air at 300 oC, and under PWR primary loop water conditions. Data are provided on materials properties related to time-independent tensile tests and time-dependent cyclic tests, such as elastic modulus, elastic and offset strain yield limit stress, and linear and nonlinear kinematic hardening model parameters. The overall objective of this report is to provide guidance to estimate tensile/fatigue hardening parameters from test data. Also, the material models and parameters reported here can directly be used in commercially available finite element codes for fatigue and ratcheting evaluation of reactor components under in-air and PWR water conditions.

  6. A Computational Study of Internal Flows in a Heated Water-Oil Emulsion Droplet

    KAUST Repository

    Sim, Jaeheon

    2015-01-05

    The vaporization characteristics of water-oil emulsion droplets are investigated by high fidelity computational simulations. One of the key objectives is to identify the physical mechanism for the experimentally observed behavior that the component in the dispersed micro-droplets always vaporizes first, for both oil-in-water and water-in-oil emulsion droplets. The mechanism of this phenomenon has not been clearly understood. In this study, an Eulerian-Lagrangian method was implemented with a temperature-dependent surface tension model and a dynamic adaptive mesh refinement in order to effectively capture the thermo-capillary effect of a micro-droplet in an emulsion droplet efficiently. It is found that the temperature difference in an emulsion droplet creates a surface tension gradient along the micro-droplet surface, inducing surface movement. Subsequently, the outer shear flow and internal flow circulation inside the droplet, referred to as the Marangoni convection, are created. The present study confirms that the Marangoni effect can be sufficiently large to drive the micro-droplets to the emulsion droplet surface at higher temperature, for both water-in-oil and oil-and-water emulsion droplets. A further parametric study with different micro-droplet sizes and temperature gradients demonstrates that larger micro-droplets move faster with larger temperature gradient. The oil micro-droplet in oil-in-water emulsion droplets moves faster due to large temperature gradients by smaller thermal conductivity.

  7. Defluoridation of drinking water by electrocoagulation/electroflotation in a stirred tank reactor with a comparative performance to an external-loop airlift reactor

    OpenAIRE

    Essadki, Abdel Hafid; Gourich, Bouchaib; Vial, Christophe; Delmas, Henri; Bennajah, Mounir

    2009-01-01

    Defluoridation using batch electrocoagulation/electroflotation (EC/EF) was carried out in two reactors for comparison purpose: a stirred tank reactor (STR) close to a conventional EC cell and an external-loop airlift reactor (ELAR) that was recently described as an innovative reactor for EC. The respective influences of current density, initial concentration and initial pH on the efficiency of defluoridation were investigated. The same trends were observed in both reactors, but the efficiency...

  8. Introduction to Loop Heat Pipes

    Science.gov (United States)

    Ku, Jentung

    2015-01-01

    This is the presentation file for the short course Introduction to Loop Heat Pipes, to be conducted at the 2015 Thermal Fluids and Analysis Workshop, August 3-7, 2015, Silver Spring, Maryland. This course will discuss operating principles and performance characteristics of a loop heat pipe. Topics include: 1) pressure profiles in the loop; 2) loop operating temperature; 3) operating temperature control; 4) loop startup; 4) loop shutdown; 5) loop transient behaviors; 6) sizing of loop components and determination of fluid inventory; 7) analytical modeling; 8) examples of flight applications; and 9) recent LHP developments.

  9. How Mg(2+) ion and water network affect the stability and structure of non-Watson-Crick base pairs in E. coli loop E of 5S rRNA: a molecular dynamics and reference interaction site model (RISM) study.

    Science.gov (United States)

    Shanker, Sudhanshu; Bandyopadhyay, Pradipta

    2017-08-01

    The non-Watson-Crick (non-WC) base pairs of Escherichia coli loop E of 5S rRNA are stabilized by Mg(2+) ions through water-mediated interaction. It is important to know the synergic role of Mg(2+) and the water network surrounding Mg(2+) in stabilizing the non-WC base pairs of RNA. For this purpose, free energy change of the system is calculated using molecular dynamics (MD) simulation as Mg(2+) is pulled from RNA, which causes disturbance of the water network. It was found that Mg(2+) remains hexahydrated unless it is close to or far from RNA. In the pentahydrated form, Mg(2+) interacts directly with RNA. Water network has been identified by two complimentary methods; MD followed by a density-based clustering algorithm and three-dimensional-reference interaction site model. These two methods gave similar results. Identification of water network around Mg(2+) and non-WC base pairs gives a clue to the strong effect of water network on the stability of this RNA. Based on sequence analysis of all Eubacteria 5s rRNA, we propose that hexahydrated Mg(2+) is an integral part of this RNA and geometry of base pairs surrounding it adjust to accommodate the [Formula: see text]. Overall the findings from this work can help in understanding the basis of the complex structure and stability of RNA with non-WC base pairs.

  10. Full-scale 3-D finite element modeling of a two-loop pressurized water reactor for heat transfer, thermal–mechanical cyclic stress analysis, and environmental fatigue life estimation

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish, E-mail: smohanty@anl.gov; Soppet, William K.; Majumdar, Saurindranath; Natesan, Krishnamurti

    2015-12-15

    Highlights: • Full-scale 3-D finite element model. • Pressurized water reactor. • Heat transfer analysis. • Thermal–mechanical stress analysis. • Environmental fatigue life estimation. - Abstract: This paper discusses a system-level finite element model of a two-loop pressurized water reactor (PWR). Based on this model, system-level heat transfer analysis and subsequent sequentially coupled thermal–mechanical stress analysis were performed for typical thermal–mechanical fatigue cycles. The in-air fatigue lives of example components, such as the hot and cold legs, were estimated on the basis of stress analysis results, ASME in-air fatigue life estimation criteria, and fatigue design curves. Furthermore, environmental correction factors and associated PWR environment fatigue lives for the hot and cold legs were estimated by using estimated stress and strain histories and the approach described in US-NRC report: NUREG-6909.

  11. Blind Loop Syndrome

    Science.gov (United States)

    ... of tissue that protrude through the intestinal wall (diverticulosis) Certain medical conditions, including Crohn's disease, radiation enteritis, ... History of radiation therapy to the abdomen Diabetes Diverticulosis of the small intestine A blind loop can ...

  12. The Cinderella loop project

    Science.gov (United States)

    Schmelz, J. T.; Beene, J.; Coyle, T.; Douglass, J.; Nasraoui, K.; O'Connor, J.; Roames, J.; Scott, M.

    2006-01-01

    The solar loop that formed off the northeast limb of the Sun on 1999 November 6 (a.k.a. the Cinderella loop) is one of the few examples of a loop on the limb observed with all three of the following imaging instruments: the Transition Region and Coronal Explorer (TRACE), the SOHO Extreme-ultraviolet Imaging Telescope (EIT), and the Yohkoh Soft X-ray Telescope (SXT). In this project we investigate the temperature differences that result when examining the Cinderella loop with one instrument compared with another. For example, what temperature differences result from the increased spatial resolution between the two EUV imagers? More specifically, given that TRACE and EIT have almost identical temperature response to coronal plasma, does the different spatial resolution of TRACE (with 0.5″ pixels) and EIT (with 2.6″ pixels) produce statistically different results? We find that the answer is no, and that our results do not change after background subtraction. In addition, the spatial resolution of EIT and SXT is similar, but the temperature responses of the two instruments are quite different. The two instruments do not seem to be viewing the same loop strands, and the plasma temperature differences are significant.

  13. Closing global material loops

    DEFF Research Database (Denmark)

    Prosman, Ernst-Jan; Wæhrens, Brian Vejrum; Liotta, Giacomo

    2017-01-01

    Replacing virgin materials with waste materials, a practice known as Industrial Symbiosis (IS), has been identified as a key strategy for closing material loops. This article adopts a critical view on geographic proximity and external coordinators – two key enablers of IS. By ‘uncovering’ a case...... for geographic proximity and external coordinators. In doing so, our insights into firm-level challenges of long-distance IS exchanges contribute to closing global material loops by increasing the number of potential circular pathways....

  14. Hidden-loop colostomy.

    Science.gov (United States)

    Rombeau, J L; Turnbul, R B

    1978-04-01

    Records of 15 patients having hidden-loop colostomies were reviewed. All patients had metastatic colonic cancers with impending obstructions. Six colostomies were subsequently opened because of obstructions due to cancer. All colostomy openings were done using local anesthesia in the emergency room. This technique prevented six major celiotomies and provided additional time of living without a stoma. There were two postoperative stomal prolapses, one of which necessitated reoperation. A hidden-loop colostomy is easily constructed and readily opened. It should be considered at celiotomy for selected patients who have metastatic colonic cancer with impending obstruction.

  15. Full-Scale 3-D Finite Element Modeling of a Two-Loop Pressurized Water Reactor for Heat Transfer, Thermal-Mechanical Cyclic Stress Analysis, and Environmental Fatigue Life Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish; Soppet, William K.; Majumdar, Saurindranath; Natesan, Krishnamurti

    2015-12-15

    This paper discusses a system-level finite element model of a two-loop pressurized water reactor (PWR). Based on this model, system-level heat transfer analysis and subsequent sequentially coupled thermal-mechanical stress analysis were performed for typical thermal-mechanical fatigue cycles. The in-air fatigue lives of example components, such as the hot and cold legs, were estimated on the basis of stress analysis results, ASME in-air fatigue life estimation criteria, and fatigue design curves. Furthermore, environmental correction factors and associated PWR environment fatigue lives for the hot and cold legs were estimated by using estimated stress and strain histories and the approach described in US-NRC report: NUREG-6909.

  16. Loop Quantum Gravity

    Directory of Open Access Journals (Sweden)

    Rovelli Carlo

    1998-01-01

    Full Text Available The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. Research in loop quantum gravity today forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained are: (i The computation of the physical spectra of geometrical quantities such as area and volume, which yields quantitative predictions on Planck-scale physics. (ii A derivation of the Bekenstein-Hawking black hole entropy formula. (iii An intriguing physical picture of the microstructure of quantum physical space, characterized by a polymer-like Planck scale discreteness. This discreteness emerges naturally from the quantum theory and provides a mathematically well-defined realization of Wheeler's intuition of a spacetime ``foam''. Long standing open problems within the approach (lack of a scalar product, over-completeness of the loop basis, implementation of reality conditions have been fully solved. The weak part of the approach is the treatment of the dynamics: at present there exist several proposals, which are intensely debated. Here, I provide a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  17. LAPAROSCOPIC ILEAL LOOP CONDUIT

    African Journals Online (AJOL)

    Then the right ureter was laparoscopically spa- tulated and anastomosed to the ileostomy opening using interrupted 4/0 vicryl sutures. After finishing half the circumference of the anastomotic line, a 4 Fr. ureteric catheter was introduced through the external stoma of the loop up to the site of the anastomosis with the aid of a ...

  18. Improving Loop Dependence Analysis

    DEFF Research Database (Denmark)

    Jensen, Nicklas Bo; Karlsson, Sven

    2017-01-01

    Programmers can no longer depend on new processors to have significantly improved single-thread performance. Instead, gains have to come from other sources such as the compiler and its optimization passes. Advanced passes make use of information on the dependencies related to loops. We improve th...

  19. Numerical simulation of a natural circulation loop

    Energy Technology Data Exchange (ETDEWEB)

    Verissimo, Gabriel L.; Moreira, Maria de Lourdes; Faccini, Jose Luiz H., E-mail: gabrielverissimo@poli.ufrj.b, E-mail: malu@ien.gov.b, E-mail: faccini@ien.gov.b [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    This work presents a numerical simulation of a natural circulation loop using computational fluid dynamics. The simulated loop is an experimental model in a reduced scale of 1:10 of a passive heat removal system typical of advanced PWR reactors. The loop is composed of a heating vessel containing 52 electric heaters, a vertical shell-tube heat exchanger and a column of expansion. The working fluid is distilled water. Initially it was created a tridimensional geometric model of the loop components. After that, it was generated a tridimensional mesh of finite elements in order to calculate the variables of the problem. The boundaries of the numerical simulation were the power of the electric resistances and the cooling flow in the secondary side of the heat exchanger. The initial conditions were the temperature, the pressure and the fluid velocity at the time just before the power has been switched on. The results of this simulation were compared with the experimental data, in terms of the evolution of the temperatures in different locations of the loop, and of the average natural circulation flow as a function of time for a given power. (author)

  20. Loop Quantum Cosmology.

    Science.gov (United States)

    Bojowald, Martin

    2008-01-01

    Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time. Supplementary material is available for this article at 10.12942/lrr-2008-4.

  1. PAR Loop Schedule Review

    Energy Technology Data Exchange (ETDEWEB)

    Schaffer, Jr.; W.F.

    1958-04-30

    The schedule for the installation of the PAR slurry loop experiment in the South Facility of the ORR has been reviewed and revised. The design, fabrications and Installation is approximately two weeks behind schedule at this time due to many factors; however, indications are that this time can be made up. Design is estimated to be 75% complete, fabrication 32% complete and installation 12% complete.

  2. Loop Quantum Cosmology

    Directory of Open Access Journals (Sweden)

    Bojowald Martin

    2008-07-01

    Full Text Available Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time.

  3. Loop Quantum Cosmology

    Directory of Open Access Journals (Sweden)

    Bojowald Martin

    2005-12-01

    Full Text Available Quantum gravity is expected to be necessary in order to understand situations where classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical space-time inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding space-time is then modified. One particular realization is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. Main effects are introduced into effective classical equations which allow to avoid interpretational problems of quantum theory. They give rise to new kinds of early universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function which allows to extend space-time beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of space-time arising in loop quantum gravity and its application to cosmology sheds new light on more general issues such as time.

  4. Cosmic string loop microlensing

    Science.gov (United States)

    Bloomfield, Jolyon K.; Chernoff, David F.

    2014-06-01

    Cosmic superstring loops within the galaxy microlens background point sources lying close to the observer-string line of sight. For suitable alignments, multiple paths coexist and the (achromatic) flux enhancement is a factor of two. We explore this unique type of lensing by numerically solving for geodesics that extend from source to observer as they pass near an oscillating string. We characterize the duration of the flux doubling and the scale of the image splitting. We probe and confirm the existence of a variety of fundamental effects predicted from previous analyses of the static infinite straight string: the deficit angle, the Kaiser-Stebbins effect, and the scale of the impact parameter required to produce microlensing. Our quantitative results for dynamical loops vary by O(1) factors with respect to estimates based on infinite straight strings for a given impact parameter. A number of new features are identified in the computed microlensing solutions. Our results suggest that optical microlensing can offer a new and potentially powerful methodology for searches for superstring loop relics of the inflationary era.

  5. LoopIng: a template-based tool for predicting the structure of protein loops.

    KAUST Repository

    Messih, Mario Abdel

    2015-08-06

    Predicting the structure of protein loops is very challenging, mainly because they are not necessarily subject to strong evolutionary pressure. This implies that, unlike the rest of the protein, standard homology modeling techniques are not very effective in modeling their structure. However, loops are often involved in protein function, hence inferring their structure is important for predicting protein structure as well as function.We describe a method, LoopIng, based on the Random Forest automated learning technique, which, given a target loop, selects a structural template for it from a database of loop candidates. Compared to the most recently available methods, LoopIng is able to achieve similar accuracy for short loops (4-10 residues) and significant enhancements for long loops (11-20 residues). The quality of the predictions is robust to errors that unavoidably affect the stem regions when these are modeled. The method returns a confidence score for the predicted template loops and has the advantage of being very fast (on average: 1 min/loop).www.biocomputing.it/loopinganna.tramontano@uniroma1.itSupplementary data are available at Bioinformatics online.

  6. Coupled dual loop absorption heat pump

    Science.gov (United States)

    Sarkisian, Paul H.; Reimann, Robert C.; Biermann, Wendell J.

    1985-01-01

    A coupled dual loop absorption system which utilizes two separate complete loops. Each individual loop operates at three temperatures and two pressures. This low temperature loop absorber and condenser are thermally coupled to the high temperature loop evaporator, and the high temperature loop condenser and absorber are thermally coupled to the low temperature generator.

  7. Wilson loops as precursors

    Energy Technology Data Exchange (ETDEWEB)

    Susskind, Leonard [Department of Physics, Stanford University, Stanford, California 94305-4060 (United States); Toumbas, Nicolaos [Department of Physics, Stanford University, Stanford, California 94305-4060 (United States)

    2000-02-15

    There is substantial evidence that string theory on AdS{sub 5}xS{sub 5} is a holographic theory in which the number of degrees of freedom scales as the area of the boundary in Planck units. Precisely how the theory can describe bulk physics using only surface degrees of freedom is not well understood. A particularly paradoxical situation involves an event deep in the interior of the bulk space. The event must be recorded in the (Schroedinger picture) state vector of the boundary theory long before a signal, such as a gravitational wave, can propagate from the event to the boundary. In a previous paper with Polchinski, we argued that the ''precursor'' operators which carry information stored in the wave during the time when it vanishes in a neighborhood of the boundary are necessarily non-local. In this paper we argue that the precursors cannot be products of local gauge invariant operators such as the energy momentum tensor. In fact gauge theories have a class of intrinsically non-local operators which cannot be built from local gauge invariant objects. These are the Wilson loops. We show that the precursors can be identified with Wilson loops whose spatial size is dictated by the UV-IR connection. (c) 2000 The American Physical Society.

  8. High temperature storage loop :

    Energy Technology Data Exchange (ETDEWEB)

    Gill, David Dennis; Kolb, William J.

    2013-07-01

    A three year plan for thermal energy storage (TES) research was created at Sandia National Laboratories in the spring of 2012. This plan included a strategic goal of providing test capability for Sandia and for the nation in which to evaluate high temperature storage (>650ÀC) technology. The plan was to scope, design, and build a flow loop that would be compatible with a multitude of high temperature heat transfer/storage fluids. The High Temperature Storage Loop (HTSL) would be reconfigurable so that it was useful for not only storage testing, but also for high temperature receiver testing and high efficiency power cycle testing as well. In that way, HTSL was part of a much larger strategy for Sandia to provide a research and testing platform that would be integral for the evaluation of individual technologies funded under the SunShot program. DOEs SunShot program seeks to reduce the price of solar technologies to 6/kWhr to be cost competitive with carbon-based fuels. The HTSL project sought to provide evaluation capability for these SunShot supported technologies. This report includes the scoping, design, and budgetary costing aspects of this effort

  9. Loop Quantum Gravity.

    Science.gov (United States)

    Rovelli, Carlo

    2008-01-01

    The problem of describing the quantum behavior of gravity, and thus understanding quantum spacetime, is still open. Loop quantum gravity is a well-developed approach to this problem. It is a mathematically well-defined background-independent quantization of general relativity, with its conventional matter couplings. Today research in loop quantum gravity forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained so far are: (i) The computation of the spectra of geometrical quantities such as area and volume, which yield tentative quantitative predictions for Planck-scale physics. (ii) A physical picture of the microstructure of quantum spacetime, characterized by Planck-scale discreteness. Discreteness emerges as a standard quantum effect from the discrete spectra, and provides a mathematical realization of Wheeler's "spacetime foam" intuition. (iii) Control of spacetime singularities, such as those in the interior of black holes and the cosmological one. This, in particular, has opened up the possibility of a theoretical investigation into the very early universe and the spacetime regions beyond the Big Bang. (iv) A derivation of the Bekenstein-Hawking black-hole entropy. (v) Low-energy calculations, yielding n-point functions well defined in a background-independent context. The theory is at the roots of, or strictly related to, a number of formalisms that have been developed for describing background-independent quantum field theory, such as spin foams, group field theory, causal spin networks, and others. I give here a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  10. Loop Quantum Gravity

    Directory of Open Access Journals (Sweden)

    Rovelli Carlo

    2008-07-01

    Full Text Available The problem of describing the quantum behavior of gravity, and thus understanding quantum spacetime, is still open. Loop quantum gravity is a well-developed approach to this problem. It is a mathematically well-defined background-independent quantization of general relativity, with its conventional matter couplings. Today research in loop quantum gravity forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained so far are: (i The computation of the spectra of geometrical quantities such as area and volume, which yield tentative quantitative predictions for Planck-scale physics. (ii A physical picture of the microstructure of quantum spacetime, characterized by Planck-scale discreteness. Discreteness emerges as a standard quantum effect from the discrete spectra, and provides a mathematical realization of Wheeler’s “spacetime foam” intuition. (iii Control of spacetime singularities, such as those in the interior of black holes and the cosmological one. This, in particular, has opened up the possibility of a theoretical investigation into the very early universe and the spacetime regions beyond the Big Bang. (iv A derivation of the Bekenstein–Hawking black-hole entropy. (v Low-energy calculations, yielding n-point functions well defined in a background-independent context. The theory is at the roots of, or strictly related to, a number of formalisms that have been developed for describing background-independent quantum field theory, such as spin foams, group field theory, causal spin networks, and others. I give here a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  11. Loop quantum cosmology: Recent progress

    Indian Academy of Sciences (India)

    Aspects of the full theory of loop quantum gravity can be studied in a simpler context by reducing to symmetric models like cosmological ones. This leads to several applications where loop effects play a significant role when one is sensitive to the quantum regime. As a consequence, the structure of and the approach to ...

  12. A solar assisted polygeneration system integrating methane reforming and chemical looping combustion with zero carbon emission

    National Research Council Canada - National Science Library

    WANG, Jiangjiang; FU, Chao

    2017-01-01

    .... This paper combines chemical-looping combustion (CLC) and methane reforming with CO2 to accomplish CO2 capture and utilization and proposes a novel polygeneration system to produce syngas, electricity, chilled water for cooling, and hot water...

  13. The loop gravity string

    CERN Document Server

    Freidel, Laurent; Pranzetti, Daniele

    2016-01-01

    In this work we study canonical gravity in finite regions for which we introduce a generalisation of the Gibbons-Hawking boundary term including the Immirzi parameter. We study the canonical formulation on a spacelike hypersuface with a boundary sphere and show how the presence of this term leads to an unprecedented type of degrees of freedom coming from the restoration of the gauge and diffeomorphism symmetry at the boundary. In the presence of a loop quantum gravity state, these boundary degrees of freedom localize along a set of punctures on the boundary sphere. We demonstrate that these degrees of freedom are effectively described by auxiliary strings with a 3-dimensional internal target space attached to each puncture. We show that the string currents represent the local frame field, that the string angular momenta represent the area flux and that the string stress tensor represents the two dimensional metric on the boundary of the region of interest. Finally, we show that the commutators of these broken...

  14. How long is a piece of loop?

    Directory of Open Access Journals (Sweden)

    Yoonjoo Choi

    2013-02-01

    Full Text Available Loops are irregular structures which connect two secondary structure elements in proteins. They often play important roles in function, including enzyme reactions and ligand binding. Despite their importance, their structure remains difficult to predict. Most protein loop structure prediction methods sample local loop segments and score them. In particular protein loop classifications and database search methods depend heavily on local properties of loops. Here we examine the distance between a loop’s end points (span. We find that the distribution of loop span appears to be independent of the number of residues in the loop, in other words the separation between the anchors of a loop does not increase with an increase in the number of loop residues. Loop span is also unaffected by the secondary structures at the end points, unless the two anchors are part of an anti-parallel beta sheet. As loop span appears to be independent of global properties of the protein we suggest that its distribution can be described by a random fluctuation model based on the Maxwell–Boltzmann distribution. It is believed that the primary difficulty in protein loop structure prediction comes from the number of residues in the loop. Following the idea that loop span is an independent local property, we investigate its effect on protein loop structure prediction and show how normalised span (loop stretch is related to the structural complexity of loops. Highly contracted loops are more difficult to predict than stretched loops.

  15. Mercury Thermal Hydraulic Loop (MTHL) Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Felde, David K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Crye, Jason Michael [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wendel, Mark W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yoder, Jr, Graydon L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Farquharson, George [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jallouk, Philip A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McFee, Marshall T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pointer, William David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ruggles, Art E. [Univ. of Tennessee, Knoxville, TN (United States); Carbajo, Juan J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-03-01

    The Spallation Neutron Source (SNS) is a high-power linear accelerator built at Oak Ridge National Laboratory (ORNL) which incorporates the use of a flowing liquid mercury target. The Mercury Thermal Hydraulic Loop (MTHL) was constructed to investigate and verify the heat transfer characteristics of liquid mercury in a rectangular channel. This report provides a compilation of previously reported results from the water-cooled and electrically heated straight and curved test sections that simulate the geometry of the window cooling channel in the target nose region.

  16. Water

    Science.gov (United States)

    ... www.girlshealth.gov/ Home Nutrition Nutrition basics Water Water Did you know that water makes up more ... to drink more water Other drinks How much water do you need? top Water is very important, ...

  17. Study of loop-loop and loop-edge dislocation interactions in bcc iron

    DEFF Research Database (Denmark)

    Osetsky, Y.N.; Bacon, D.J.; Gao, F.

    2000-01-01

    that the evolution of heterogeneities such as dislocation decoration and rafts has serious impacts on the mechanical properties on neutron-irradiated metals. In the present work, atomic-scale computer modelling (ASCM) has been applied to study the mechanisms for the formation of such microstructure in bcc iron....... It is shown that glissile clusters with parallel Burgers vectors interact strongly and can form extended immobile complexes, i.e., rafts. Similar attractive interaction exists between dislocation loops and an edge dislocation. These two mechanisms may be responsible for the formation of extended complexes...... of dislocation loops below the extra half-plane of edge dislocations. The interaction energies between loops and between an edge dislocation and loops has been calculated as a function of distance using ASCM and the results for long-range interactions are in good agreement with the results of isotropic...

  18. N -loop running should be combined with N -loop matching

    Science.gov (United States)

    Braathen, Johannes; Goodsell, Mark D.; Krauss, Manuel E.; Opferkuch, Toby; Staub, Florian

    2018-01-01

    We investigate the high-scale behavior of Higgs sectors beyond the Standard Model, pointing out that the proper matching of the quartic couplings before applying the renormalization group equations (RGEs) is of crucial importance for reliable predictions at larger energy scales. In particular, the common practice of leading-order parameters in the RGE evolution is insufficient to make precise statements on a given model's UV behavior, typically resulting in uncertainties of many orders of magnitude. We argue that, before applying N -loop RGEs, a matching should even be performed at N -loop order in contrast to common lore. We show both analytical and numerical results where the impact is sizable for three minimal extensions of the Standard Model: a singlet extension, a second Higgs doublet and finally vector-like quarks. We highlight that the known two-loop RGEs tend to moderate the running of their one-loop counterparts, typically delaying the appearance of Landau poles. For the addition of vector-like quarks we show that the complete two-loop matching and RGE evolution hints at a stabilization of the electroweak vacuum at high energies, in contrast to results in the literature.

  19. Kalman Orbit Optimized Loop Tracking

    Science.gov (United States)

    Young, Lawrence E.; Meehan, Thomas K.

    2011-01-01

    Under certain conditions of low signal power and/or high noise, there is insufficient signal to noise ratio (SNR) to close tracking loops with individual signals on orbiting Global Navigation Satellite System (GNSS) receivers. In addition, the processing power available from flight computers is not great enough to implement a conventional ultra-tight coupling tracking loop. This work provides a method to track GNSS signals at very low SNR without the penalty of requiring very high processor throughput to calculate the loop parameters. The Kalman Orbit-Optimized Loop (KOOL) tracking approach constitutes a filter with a dynamic model and using the aggregate of information from all tracked GNSS signals to close the tracking loop for each signal. For applications where there is not a good dynamic model, such as very low orbits where atmospheric drag models may not be adequate to achieve the required accuracy, aiding from an IMU (inertial measurement unit) or other sensor will be added. The KOOL approach is based on research JPL has done to allow signal recovery from weak and scintillating signals observed during the use of GPS signals for limb sounding of the Earth s atmosphere. That approach uses the onboard PVT (position, velocity, time) solution to generate predictions for the range, range rate, and acceleration of the low-SNR signal. The low- SNR signal data are captured by a directed open loop. KOOL builds on the previous open loop tracking by including feedback and observable generation from the weak-signal channels so that the MSR receiver will continue to track and provide PVT, range, and Doppler data, even when all channels have low SNR.

  20. Study of the Open Loop and Closed Loop Oscillator Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Imel, George R. [Idaho State Univ., Pocatello, ID (United States); Baker, Benjamin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Riley, Tony [Knolls Atomic Power Lab. (KAPL), Schenectady, NY (United States); Langbehn, Adam [Puget Sound Naval Base, Bremerton, WA (United States); Aryal, Harishchandra [Idaho State Univ., Pocatello, ID (United States); Benzerga, M. Lamine [Idaho State Univ., Pocatello, ID (United States)

    2015-04-11

    This report presents the progress and completion of a five-year study undertaken at Idaho State University of the measurement of very small worth reactivity samples comparing open and closed loop oscillator techniques.The study conclusively demonstrated the equivalency of the two techniques with regard to uncertainties in reactivity values, i.e., limited by reactor noise. As those results are thoroughly documented in recent publications, in this report we will concentrate on the support work that was necessary. For example, we describe in some detail the construction and calibration of a pilot rod for the closed loop system. We discuss the campaign to measure the required reactor parameters necessary for inverse-kinetics. Finally, we briefly discuss the transfer of the open loop technique to other reactor systems.

  1. CLOSED-LOOP STRIPPING ANALYSIS (CLSA) OF ...

    Science.gov (United States)

    Synthetic musk compounds have been found in surface water, fish tissues, and human breast milk. Current techniques for separating these compounds from fish tissues require tedious sample clean-upprocedures A simple method for the deterrnination of these compounds in fish tissues has been developed. Closed-loop stripping of saponified fish tissues in a I -L Wheaton purge-and-trap vessel is used to strip compounds with high vapor pressures such as synthetic musks from the matrix onto a solid sorbent (Abselut Nexus). This technique is useful for screening biological tissues that contain lipids for musk compounds. Analytes are desorbed from the sorbent trap sequentially with polar and nonpolar solvents, concentrated, and directly analyzed by high resolution gas chromatography coupled to a mass spectrometer operating in the selected ion monitoring mode. In this paper, we analyzed two homogenized samples of whole fish tissues with spiked synthetic musk compounds using closed-loop stripping analysis (CLSA) and pressurized liquid extraction (PLE). The analytes were not recovered quantitatively but the extraction yield was sufficiently reproducible for at least semi-quantitative purposes (screening). The method was less expensive to implement and required significantly less sample preparation than the PLE technique. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water,

  2. Vertically Polarized Omnidirectional Printed Slot Loop AntennaPrinted Slot Loop Antenna (invited)

    DEFF Research Database (Denmark)

    Kammersgaard, Nikolaj Peter Iversen; Kvist, Søren Helstrup; Thaysen, Jesper

    2015-01-01

    A novel verticall A novel vertically polarized dpolarize , omnidirection omnidirectional l , printed slot loop antenna h sprinted slot loop antenna has been designed, simulated, fabricated, and measured. The slot loop works as a magnetic loop. The loop is loaded with inductors to insure uniform a...

  3. Opportunities and Challenges of Multi-Loop Aquaponic Systems

    NARCIS (Netherlands)

    Goddek, Simon

    2017-01-01

    Climate change requires new and innovative agricultural approaches to food security, especially in countries facing water scarcity. In this context, aquaponics could constitute a partial solution to tackle this issue. Traditional designs for one-loop aquaponic systems comprise of both aquaculture

  4. Closed loop obstruction: pictorial essay.

    Science.gov (United States)

    Mbengue, A; Ndiaye, A; Soko, T O; Sahnoun, M; Fall, A; Diouf, C T; Régent, D; Diakhaté, I C

    2015-02-01

    Closed loop obstruction occurs when a segment of bowel is incarcerated at two contiguous points. The diagnosis is based on multiple transitional zones. The incarcerated loops appear in U or C form or present a radial layout around the location of the obstruction. It's very important to specify the type of obstruction because, in patients with simple bowel obstruction, a conservative approach is often advised. On the other hand, a closed loop obstruction immediately requires a surgical approach because of its high morbidity and the risk of death in case of a late diagnosis. Copyright © 2013 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

  5. Effective potential at three loops

    Science.gov (United States)

    Martin, Stephen P.

    2017-11-01

    I present the effective potential at three-loop order for a general renormalizable theory, using the MS ¯ renormalization scheme and Landau gauge fixing. As applications and illustrative points of reference, the results are specialized to the supersymmetric Wess-Zumino model and to the standard model. In each case, renormalization group scale invariance provides a consistency check. In the Wess-Zumino model, the required vanishing of the minimum vacuum energy yields an additional check. For the standard model, I carry out the resummation of Goldstone boson contributions, which provides yet more opportunities for nontrivial checks, and obtain the minimization condition for the Higgs vacuum expectation value at full three-loop order. An infrared divergence due to doubled photon propagators appears in the three-loop standard model effective potential, but it does not affect the minimization condition or physical observables and can be eliminated by resummation.

  6. LISA Pathfinder: OPD loop characterisation

    Science.gov (United States)

    Born, Michael; LPF Collaboration

    2017-05-01

    The optical metrology system (OMS) of the LISA Pathfinder mission is measuring the distance between two free-floating test masses with unprecedented precision. One of the four OMS heterodyne interferometers reads out the phase difference between the reference and the measurement laser beam. This phase from the reference interferometer is common to all other longitudinal interferometer read outs and therefore subtracted. In addition, the phase is fed back via the digital optical pathlength difference (OPD) control loop to keep it close to zero. Here, we analyse the loop parameters and compare them to on-ground measurement results.

  7. Chinese Magic in Loop Integrals

    OpenAIRE

    Ward, B. F. L.

    2011-01-01

    We present an approach to higher point loop integrals using Chinese magic in the virtual loop integration variable. We show, using the five point function in the important e^+e^-\\to f\\bar{f}+\\gamma process for ISR as a pedagogical vehicle, that we get an expression for it directly reduced to one scalar 5-point function and 4-, 3-, and 2- point integrals, thereby avoiding the computation of the usual three tensor 5-pt Passarino-Veltman reduction. We argue that this offers potential for greater...

  8. Gas Test Loop Booster Fuel Hydraulic Testing

    Energy Technology Data Exchange (ETDEWEB)

    Gas Test Loop Hydraulic Testing Staff

    2006-09-01

    The Gas Test Loop (GTL) project is for the design of an adaptation to the Advanced Test Reactor (ATR) to create a fast-flux test space where fuels and materials for advanced reactor concepts can undergo irradiation testing. Incident to that design, it was found necessary to make use of special booster fuel to enhance the neutron flux in the reactor lobe in which the Gas Test Loop will be installed. Because the booster fuel is of a different composition and configuration from standard ATR fuel, it is necessary to qualify the booster fuel for use in the ATR. Part of that qualification is the determination that required thermal hydraulic criteria will be met under routine operation and under selected accident scenarios. The Hydraulic Testing task in the GTL project facilitates that determination by measuring flow coefficients (pressure drops) over various regions of the booster fuel over a range of primary coolant flow rates. A high-fidelity model of the NW lobe of the ATR with associated flow baffle, in-pile-tube, and below-core flow channels was designed, constructed and located in the Idaho State University Thermal Fluids Laboratory. A circulation loop was designed and constructed by the university to provide reactor-relevant water flow rates to the test system. Models of the four booster fuel elements required for GTL operation were fabricated from aluminum (no uranium or means of heating) and placed in the flow channel. One of these was instrumented with Pitot tubes to measure flow velocities in the channels between the three booster fuel plates and between the innermost and outermost plates and the side walls of the flow annulus. Flow coefficients in the range of 4 to 6.5 were determined from the measurements made for the upper and middle parts of the booster fuel elements. The flow coefficient for the lower end of the booster fuel and the sub-core flow channel was lower at 2.3.

  9. Dirac Induction for loop groups

    NARCIS (Netherlands)

    Posthuma, H.

    2011-01-01

    Using a coset version of the cubic Dirac operators for affine Lie algebras, we give an algebraic construction of the Dirac induction homomorphism for loop group representations. With this, we prove a homogeneous generalization of the Weyl-Kac character formula and show compatibility with Dirac

  10. Loop quantum cosmology and singularities.

    Science.gov (United States)

    Struyve, Ward

    2017-08-15

    Loop quantum gravity is believed to eliminate singularities such as the big bang and big crunch singularity. This belief is based on studies of so-called loop quantum cosmology which concerns symmetry-reduced models of quantum gravity. In this paper, the problem of singularities is analysed in the context of the Bohmian formulation of loop quantum cosmology. In this formulation there is an actual metric in addition to the wave function, which evolves stochastically (rather than deterministically as the case of the particle evolution in non-relativistic Bohmian mechanics). Thus a singularity occurs whenever this actual metric is singular. It is shown that in the loop quantum cosmology for a homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker space-time with arbitrary constant spatial curvature and cosmological constant, coupled to a massless homogeneous scalar field, a big bang or big crunch singularity is never obtained. This should be contrasted with the fact that in the Bohmian formulation of the Wheeler-DeWitt theory singularities may exist.

  11. Loop quantum gravity and observations

    CERN Document Server

    Barrau, A

    2014-01-01

    Quantum gravity has long been thought to be completely decoupled from experiments or observations. Although it is true that smoking guns are still missing, there are now serious hopes that quantum gravity phenomena might be tested. We review here some possible ways to observe loop quantum gravity effects either in the framework of cosmology or in astroparticle physics.

  12. Scalar one-loop integrals

    NARCIS (Netherlands)

    Veltman, M.J.G.; Hooft, G. 't

    1979-01-01

    The completely general one-loop scalar one-, two-, three- and four-point functions are studied. Also an integral occurring in connection with soft bremsstrahlung is considered. Formulas in terms of Spence functions are given. An expansion for Spence functions with complex argument is presented.

  13. Two loops in eleven dimensions

    CERN Document Server

    Green, Michael B.; Vanhove, Pierre; Green, Michael B.; Kwon, Hwang-h.; Vanhove, Pierre

    2000-01-01

    The two-loop Feynman diagram contribution to the four-graviton amplitude of eleven-dimensional supergravity compactified on a two-torus, T^2, is analyzed in detail. The Schwinger parameter integrations are re-expressed as integration over the moduli space of a second torus, \\hat T^2, which enables the leading low-momentum contribution to be evaluated in terms of maps of \\hat T^2 into T^2. The ultraviolet divergences associated with boundaries of moduli space are regularized in a manner that is consistent with the expected duality symmetries of string theory. This leads to an exact expression for terms of order contraction of four Weyl tensors), thereby extending earlier results for the R^4 term that were based on the one-loop eleven-dimensional amplitude. Precise agreement is found with terms in type IIA and IIB superstring theory that arise from the low energy expansion of the tree-level and one-loop string amplitudes and predictions are made for the coefficients of certain two-loop string theory terms as we...

  14. Modified Continuous Loop Technique for microvascular anastomosis

    Directory of Open Access Journals (Sweden)

    Kumar Pramod

    2001-01-01

    Full Text Available A modified method of continuous loop technique for microvascular anastomosis is described. The handling of loop is easier & even last suture is placed under vision. This makes the microvascular anastomosis easier and simpler.

  15. A True Open-Loop Synchronization Technique

    DEFF Research Database (Denmark)

    Golestan, Saeed; Vidal, Ana; Yepes, Alejandro G.

    2016-01-01

    Synchronization techniques can be broadly classified into two major categories: Closed-loop and open-loop methods. The open-loop synchronization (OLS) techniques, contrary to the closed-loop ones, are unconditionally stable and benefit from a fast dynamic response. Their performance, however, tends...... is to develop a true OLS (and therefore, unconditionally stable) technique without any need for the calculation of sine and cosine functions. The effectiveness of the proposed synchronization technique is confirmed through the simulation and experimental results....

  16. Estimation of complex permittivity using loop antenna

    DEFF Research Database (Denmark)

    Lenler-Eriksen, Hans-Rudolph; Meincke, Peter

    2004-01-01

    A method for estimating the complex permittivity of materials in the vicinity of a loop antenna is proposed. The method is based on comparing measured and numerically calculated input admittances for the loop antenna.......A method for estimating the complex permittivity of materials in the vicinity of a loop antenna is proposed. The method is based on comparing measured and numerically calculated input admittances for the loop antenna....

  17. Loop connectors in dentogenic diastema

    Directory of Open Access Journals (Sweden)

    Sanjna Nayar

    2015-01-01

    Full Text Available Patients with a missing tooth along with diastema have limited treatment options to restore the edentulous space. The use of a conventional fixed partial denture (FPD to replace the missing tooth may result in too wide anterior teeth leading to poor esthetics. Loss of anterior teeth with existing diastema may result in excess space available for pontic. This condition presents great esthetic challenge for prosthodontist. If implant supported prosthesis is not possible because of inadequate bone support, FPD along with loop connector may be a treatment option to maintain the diastema and provide optimal esthetic restoration. Here, we report a clinical case where FPD along with loop connector was used to achieve esthetic rehabilitation in maxillary anterior region in which midline diastema has been maintained.

  18. Chiral logarithms to five loops

    OpenAIRE

    Bissegger, Moritz; Fuhrer, Andreas

    2006-01-01

    We investigate two specific Green functions in the framework of chiral perturbation theory. We show that, using analyticity and unitarity, their leading logarithmic singularities can be evaluated in the chiral limit to any desired order in the chiral expansion, with a modest calculational cost. The claim is illustrated with an evaluation of the leading logarithm for the scalar two-point function to five-loop order.

  19. Water

    Science.gov (United States)

    ... environment and your health: Green living Sun Water Health effects of water pollution How to protect yourself from water pollution Air Chemicals Noise Quizzes Links to more information girlshealth glossary girlshealth. ...

  20. CFD simulation of a four-loop PWR at asymmetric operation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Jian-Ping; Yan, Li-Ming; Li, Feng-Chen, E-mail: lifch@hit.edu.cn

    2016-04-15

    Highlights: • A CFD numerical simulation procedure was established for simulating RPV of VVER-1000. • The established CFD approach was validated by comparing with available data. • Thermal hydraulic characteristics under asymmetric operation condition were investigated. • Apparent influences of the shutdown loop on its neighboring loops were obtained. - Abstract: The pressurized water reactor (PWR) with multiple loops may have abnormal working conditions with coolant pumps out of running in some loops. In this paper, a computational fluid dynamics (CFD) numerical study of the four-loop VVER-1000 PWR pressure vessel model was presented. Numerical simulations of the thermohydrodynamic characteristics in the pressure vessel were carried out at different inlet conditions with four and three loops running, respectively. At normal stead-state condition (four-loop running), different parameters were obtained for the full fluid domain, including pressure losses across different parts, pressure, velocity and temperature distributions in the reactor pressure vessel (RPV) and mass flow distribution of the coolant at the inlet of reactor core. The obtained results for pressure losses matched with the experimental reference values of the VVER-1000 PWR at Tianwan nuclear power plant (NPP). For most fuel assemblies (FAs), the inlet flow rates presented a symmetrical distribution about the center under full-loop operation conditions, which accorded with the practical distribution. These results indicate that it is now possible to study the dynamic transition process between different asymmetric operation conditions in a multi-loop PWR using the established CFD method.

  1. Absolute free energy and entropy of a mobile loop of the enzyme acetylcholinesterase.

    Science.gov (United States)

    Mihailescu, Mihail; Meirovitch, Hagai

    2009-06-04

    The loop 287-290 (Ile, Phe, Arg, and Phe) of the protein acetylcholinesterase (AChE) changes its structure upon interaction of AChE with diisopropylphosphorofluoridate (DFP). Reversible dissociation measurements suggest that the free-energy (F) penalty for the loop displacement is DeltaF=Ffree-Fbound approximately -4 kcal/mol. Therefore, this loop has been the target of two studies by Olson's group for testing the efficiency of procedures for calculating F. In this paper, we test for the first time the performance of our "hypothetical scanning molecular dynamics" (HSMD) method and the validity of the related modeling for a loop with bulky side chains in explicit water. Thus, we consider only atoms of the protein that are the closest to the loop (they constitute the "template"), where the rest of the atoms are ignored. The template's atoms are fixed in the X-ray coordinates of the free protein, and the loop is capped with a sphere of TIP3P water molecules; also, the X-ray structure of the bound loop is attached to the free template. We carry out two separate MD simulations starting from the free and bound X-ray structures, where only the atoms of the loop and water are allowed to move while the template-water and template-loop (AMBER) interactions are considered. The absolute Ffree and Fbound (of the loop and water) are calculated from the corresponding trajectories. A main objective of this paper is to assess the reliability of this model, and for this several template sizes are studied capped with 80-220 water molecules. We find that consistent results for the free energy (which also agree with the experimental data above) require a template larger than a minimal size and a number of water molecules approximately equal to the experimental density of bulk water. For example, we obtain DeltaFtotal=DeltaFwater+DeltaFloop=-3.1+/-2.5 and -3.6+/-4 kcal/mol for a template consisting of 944 atoms and a sphere containing 160 and 180 waters, respectively. Our calculations

  2. Entropy and Free Energy of a Mobile Loop Based on the Crystal Structures of the Free and Bound Proteins.

    Science.gov (United States)

    Mihailescu, Mihail; Meirovitch, Hagai

    2010-08-25

    A mobile loop changes its conformation from "open" (free enzyme) to "closed" upon ligand binding. The difference in the Helmholtz free energy, ΔF(loop) between these states sheds light on the mechanism of binding. With our "hypothetical scanning molecular dynamics" (HSMD-TI) method ΔF(loop) = F(free) - F(bound) where F(free) and F(bound) are calculated from two MD samples of the free and bound loop states; the contribution of water is obtained by a thermodynamic integration (TI) procedure. In previous work the free and bound loop structures were both attached to the same "template" which was "cut" from the crystal structure of the free protein. Our results for loop 287-290 of AcetylCholineEsterase agree with the experiment, ΔF(loop)~ -4 kcal/mol if the density of the TIP3P water molecules capping the loop is close to that of bulk water, i.e., N(water) = 140 - 180 waters in a sphere of a 18 Å radius. Here we calculate ΔF(loop) for the more realistic case, where two templates are "cut" from the crystal structures, 2dfp.pdb (bound) and 2ace.pdb (free), where N(water) = 40 - 160; this requires adding a computationally more demanding (second) TI procedure. While the results for N(water) ≤ 140 are computationally sound, ΔF(loop) is always positive (18 ± 2 kcal/mol for N(water) = 140). These (disagreeing) results are attributed to the large average B-factor, 41.6 of 2dfp (23.4 Å(2) for 2ace). While this conformational uncertainty is an inherent difficulty, the (unstable) results for N(water) = 160 suggest that it might be alleviated by applying different (initial) structural optimizations to each template.

  3. Chemical Looping Technology: Oxygen Carrier Characteristics.

    Science.gov (United States)

    Luo, Siwei; Zeng, Liang; Fan, Liang-Shih

    2015-01-01

    Chemical looping processes are characterized as promising carbonaceous fuel conversion technologies with the advantages of manageable CO2 capture and high energy conversion efficiency. Depending on the chemical looping reaction products generated, chemical looping technologies generally can be grouped into two types: chemical looping full oxidation (CLFO) and chemical looping partial oxidation (CLPO). In CLFO, carbonaceous fuels are fully oxidized to CO2 and H2O, as typically represented by chemical looping combustion with electricity as the primary product. In CLPO, however, carbonaceous fuels are partially oxidized, as typically represented by chemical looping gasification with syngas or hydrogen as the primary product. Both CLFO and CLPO share similar operational features; however, the optimum process configurations and the specific oxygen carriers used between them can vary significantly. Progress in both CLFO and CLPO is reviewed and analyzed with specific focus on oxygen carrier developments that characterize these technologies.

  4. The Analysis of Loop Seal Purge Time for the KHNP Pressurizer Safety Valve Test Facility Using the GOTHIC Code

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Ae; Kim, Chang Hyun; Kweon, Gab Joo; Park, Jong Woon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

    2007-10-15

    The pressurizer safety valves (PSV) in Pressurized Water Reactors are required to provide the overpressure protection for the Reactor Coolant System (RCS) during the overpressure transients. Korea Hydro and Nuclear Power Company (KHNP) plans to build the PSV test facility for the purpose of providing the PSV pop-up characteristics and the loop seal dynamics for the new safety analysis. When the pressurizer safety valve is mounted in a loop seal configuration, the valve must initially pass the loop seal water prior to popping open on steam. The loop seal in the upstream of PSV prevents leakage of hydrogen gas or steam through the safety valve seat. This paper studies on the loop seal clearing dynamics using GOTHIC-7.2a code to verify the effects of loop seal purge time on the reactor coolant system overpressure.

  5. Assessing catchment connectivity using hysteretic loops

    Science.gov (United States)

    Davis, Jason; Masselink, Rens; Goni, Mikel; Gimenez, Rafael; Casali, Javier; Seeger, Manuel; Keesstra, Saskia

    2017-04-01

    Storm events mobilize large proportions of sediments in catchment systems. Therefore understanding catchment sediment dynamics throughout the continuity of storms and how initial catchment states act as controls on the transport of sediment to catchment outlets is important for effective catchment management. Sediment connectivity is a concept which can explain the origin, pathways and sinks of sediments within catchments (Baartman et al., 2013; Parsons et al., 2015; Masselink et al., 2016a,b; Mekonnen et al., 2016). However, sediment connectivity alone does not provide a practicable mechanism by which the catchment's initial state - and thus the location of entrained sediment in the sediment transport cascade - can be characterized. Studying the dynamic relationship between water discharge (Q) and suspended sediment (SS) at the catchment outlet can provide a valuable research tool to infer the likely source areas and flow pathways contributing to sediment transport because the relationship can be characterized by predictable hysteresis patterns. Hysteresis is observed when the sediment concentration associated with a certain flow rate is different depending on the direction in which the analysis is performed - towards the increase or towards the diminution of the flow. However, the complexity of the phenomena and factors which determine the hysteresis make its interpretation ambiguous. Previous work has described various types of hysteretic loops as well as the cause for the shape of the loop, mainly pointing to the origin of the sediments. The data set for this study comes from four experimental watersheds in Navarre (Spain), owned and maintained by the Government of Navarre. These experimental watersheds have been monitored and studied since 1996 (La Tejería and Latxaga) and 2001 (Oskotz principal and Oskotz woodland). La Tejería and Latxaga watersheds are similar to each other regarding size (approximately 200 ha), geology (marls and sandstones), soils (fine

  6. Water

    Science.gov (United States)

    Leopold, Luna Bergere; Baldwin, Helene L.

    1962-01-01

    What do you use water for?If someone asked you this question you would probably think right away of water for drinking. Then you would think of water for bathing, brushing teeth, flushing the toilet. Your list would get longer as you thought of water for cooking, washing the dishes, running the garbage grinder. Water for lawn watering, for play pools, for swimming pools, for washing the car and the dog. Water for washing machines and for air conditioning. You can hardly do without water for fun and pleasure—water for swimming, boating, fishing, water-skiing, and skin diving. In school or the public library, you need water to wash your hands, or to have a drink. If your home or school bursts into flames, quantities of water are needed to put it out.In fact, life to Americans is unthinkable without large supplies of fresh, clean water. If you give the matter a little thought, you will realize that people in many countries, even in our own, may suffer from disease and dirt simply because their homes are not equipped with running water. Imagine your own town if for some reason - an explosion, perhaps - water service were cut off for a week or several weeks. You would have to drive or walk to a neighboring town and bring water back in pails. Certainly if people had to carry water themselves they might not be inclined to bathe very often; washing clothes would be a real chore.Nothing can live without water. The earth is covered by water over three-fourths of its surface - water as a liquid in rivers, lakes and oceans, and water as ice and snow on the tops of high mountains and in the polar regions. Only one-quarter of our bodies is bone and muscle; the other three-fourths is made of water. We need water to live, and so do plants and animals. People and animals can live a long time without food, but without water they die in a few days. Without water, everything would die, and the world would turn into a huge desert.

  7. Singularities in loop quantum cosmology.

    Science.gov (United States)

    Cailleteau, Thomas; Cardoso, Antonio; Vandersloot, Kevin; Wands, David

    2008-12-19

    We show that simple scalar field models can give rise to curvature singularities in the effective Friedmann dynamics of loop quantum cosmology (LQC). We find singular solutions for spatially flat Friedmann-Robertson-Walker cosmologies with a canonical scalar field and a negative exponential potential, or with a phantom scalar field and a positive potential. While LQC avoids big bang or big rip type singularities, we find sudden singularities where the Hubble rate is bounded, but the Ricci curvature scalar diverges. We conclude that the effective equations of LQC are not in themselves sufficient to avoid the occurrence of curvature singularities.

  8. Closed-loop neuromorphic benchmarks

    CSIR Research Space (South Africa)

    Stewart, TC

    2015-11-01

    Full Text Available the study was exempt from ethical approval procedures.) Did the study presented in the manuscript involve human or animal subjects: No I v i w 1Closed-loop Neuromorphic Benchmarks Terrence C. Stewart 1,∗, Travis DeWolf 1, Ashley Kleinhans 2 and Chris..._link335 program from ev3dev-c (https://github.com/in4lio/ev3dev-c). This allows the EV3 to336 listen for UDP commands that tell it to set motor values and read sensor values. Communication with337 a PC was over a USB link (although the system also...

  9. Holomorphic curves in loop groups

    Energy Technology Data Exchange (ETDEWEB)

    Guest, M.A.; Pressley, A.N.

    1988-09-01

    It was observed by Atiyah that there is a correspondence between based gauge equivalence classes of SU/sub n/-instantons over S/sup 4/ of charge d on the one hand, and based holomorphic curves of genus zero in ..cap omega..SU/sub n/ of degree d on the other hand. In this paper we study the parameter space of such holomorphic curves which have the additional property that they lie entirely in the subgroup ..cap omega../sub alg/SU/sub n/ of algebraic loops. We describe a cell decomposition of this parameter space, and compute its complex dimension to be (2n-1)d.

  10. Gauge theory loop operators and Liouville theory

    Energy Technology Data Exchange (ETDEWEB)

    Drukker, Nadav [Humboldt Univ. Berlin (Germany). Inst. fuer Physik; Gomis, Jaume; Okuda, Takuda [Perimeter Inst. for Theoretical Physics, Waterloo, ON (Canada); Teschner, Joerg [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2009-10-15

    We propose a correspondence between loop operators in a family of four dimensional N=2 gauge theories on S{sup 4} - including Wilson, 't Hooft and dyonic operators - and Liouville theory loop operators on a Riemann surface. This extends the beautiful relation between the partition function of these N=2 gauge theories and Liouville correlators found by Alday, Gaiotto and Tachikawa. We show that the computation of these Liouville correlators with the insertion of a Liouville loop operator reproduces Pestun's formula capturing the expectation value of a Wilson loop operator in the corresponding gauge theory. We prove that our definition of Liouville loop operators is invariant under modular transformations, which given our correspondence, implies the conjectured action of S-duality on the gauge theory loop operators. Our computations in Liouville theory make an explicit prediction for the exact expectation value of 't Hooft and dyonic loop operators in these N=2 gauge theories. The Liouville loop operators are also found to admit a simple geometric interpretation within quantum Teichmueller theory as the quantum operators representing the length of geodesics. We study the algebra of Liouville loop operators and show that it gives evidence for our proposal as well as providing definite predictions for the operator product expansion of loop operators in gauge theory. (orig.)

  11. Water

    Science.gov (United States)

    ... the tap as described). 3. In all situations, drink or cook only with water that comes out of the tap cold. Water that comes out of the tap warm or hot can contain much higher levels of lead. Boiling ...

  12. Assessment of impacts by open-loop geothermal system operation on hydrogeochemical properties in riverside aquifer

    Science.gov (United States)

    Koh, E. H.; Park, B. H.; Park, J.; Lee, K. K.; Lee, S. Y.

    2016-12-01

    Open-loop ground source heat pump (GSHP) utilizes groundwater in the subsurface, which maintains constant temperature regardless of seasonal changes, to be circulated through a heat pump system coupled with pumping and injection wells. During operation of the open-loop GSHP facilities, the hydrogeochemical properties of the subsurface aquifer can be altered by contacting with atmospheric air, changing temperature and pressure. Such changes in the water quality can impede energy efficiency of the open-loop GSHP. Therefore, it is important to monitor the groundwater components regularly before and after the operation of GSHP. In the riverside area of the Yangpyeong, South Korea, an open-loop GSHP has been installed for a test research, which has objectives to improve energy efficiency of the open-loop GSHP facilities and to evaluate environmental changes caused by the GSHP operation. Because the study area is located near the Han River, it is necessary to assess hydrochemical changes of groundwater resulted by the open-loop GSHP operation in consideration of interaction between the river water and groundwater. Periodic monitoring of groundwater and river water quality had been conducted from Jan., 2014 to Apr., 2016 including the operation periods of the open-loop GSHP after Apr., 2015. As the result of the open-loop GSHP operation, there were no abrupt changes in groundwater quality parameters except an increase in Cl- concentration and decrease in DO concentration over the study area. The enriched Cl- concentration was observed in both river water and groundwater based on estimation of effects by eutrophication in the river. Lowering DO concentration throughout the study area was affected by re-injection of the pumped groundwater with depleted DO during the GSHP operation with an increase of Fe2+ concentration. Such changes in the water chemistry were evaluated not to give a harmful influence on the long-term operation of the GSHP system in the study area.

  13. Magnetic fields with photon beams: use of circular current loops.

    Science.gov (United States)

    Jette, D

    2001-10-01

    Strong transverse magnetic fields can produce very large dose enhancements and reductions in localized regions of a patient under irradiation by a photon beam. Through EGS4 Monte Carlo simulations, we have examined the effects of applying a magnetic field produced by a pair of circular current loops to a photon beam penetrating a water phantom of finite thickness. We have indeed found very substantial localized dose enhancements, albeit with no corresponding dose reduction just distal to the region of dose enhancement. (However, dose reduction does occur near the distal end of the phantom.) We have also observed two phenomena to be concerned with, for this configuration: significant broadening of the penumbra close to the current loop, and narrowness of the enhanced dose region in a plane parallel to the planes of the loops. We have also examined the use of a single current loop to produce the magnetic field, and have found great asymmetry in the dose distribution; this asymmetry appears to make it impossible to treat with a single circular magnet a tumor of large dimension extending below the application surface.

  14. Polyakov loop modeling for hot QCD

    Science.gov (United States)

    Fukushima, Kenji; Skokov, Vladimir

    2017-09-01

    We review theoretical aspects of quantum chromodynamics (QCD) at finite temperature. The most important physical variable to characterize hot QCD is the Polyakov loop, which is an approximate order parameter for quark deconfinement in a hot gluonic medium. Additionally to its role as an order parameter, the Polyakov loop has rich physical contents in both perturbative and non-perturbative sectors. This review covers a wide range of subjects associated with the Polyakov loop from topological defects in hot QCD to model building with coupling to the Polyakov loop.

  15. Vertically Polarized Omnidirectional Printed Slot Loop Antenna

    DEFF Research Database (Denmark)

    Kammersgaard, Nikolaj Peter Iversen; Kvist, Søren H.; Thaysen, Jesper

    2015-01-01

    A novel vertically polarized omnidirectional printed slot loop antenna has been designed, simulated, fabricated and measured. The slot loop works as a magnetic loop. The loop is loaded with inductors to insure uniform and in-phase fields in the slot in order to obtain an omnidirectional radiation...... pattern. The antenna is designed for the 2.45 GHz Industrial, Scientific and Medical band. Applications of the antenna are many. One is for on-body applications since it is ideal for launching a creeping waves due to the polarization....

  16. Nonlinear Bayesian Tracking Loops for Multipath Mitigation

    Directory of Open Access Journals (Sweden)

    Pau Closas

    2012-01-01

    Full Text Available This paper studies Bayesian filtering techniques applied to the design of advanced delay tracking loops in GNSS receivers with multipath mitigation capabilities. The analysis includes tradeoff among realistic propagation channel models and the use of a realistic simulation framework. After establishing the mathematical framework for the design and analysis of tracking loops in the context of GNSS receivers, we propose a filtering technique that implements Rao-Blackwellization of linear states and a particle filter for the nonlinear partition and compare it to traditional delay lock loop/phase lock loop-based schemes.

  17. Soft Neutrosophic Loops and Their Generalization

    Directory of Open Access Journals (Sweden)

    Mumtaz Ali

    2014-06-01

    Full Text Available Soft set theory is a general mathematical tool for dealing with uncertain, fuzzy, not clearly defined objects. In this paper we introduced soft neutrosophic loop,soft neutosophic biloop, soft neutrosophic N -loop with the discuission of some of their characteristics. We also introduced a new type of soft neutrophic loop, the so called soft strong neutrosophic loop which is of pure neutrosophic character. This notion also found in all the other corresponding notions of soft neutrosophic thoery. We also given some of their properties of this newly born soft structure related to the strong part of neutrosophic theory.

  18. Development and Implementation of a Design Metric for Systems Containing Long-Term Fluid Loops

    Science.gov (United States)

    Steele, John W.

    2016-01-01

    John Steele, a chemist and technical fellow from United Technologies Corporation, provided a water quality module to assist engineers and scientists with a metric tool to evaluate risks associated with the design of space systems with fluid loops. This design metric is a methodical, quantitative, lessons-learned based means to evaluate the robustness of a long-term fluid loop system design. The tool was developed by a cross-section of engineering disciplines who had decades of experience and problem resolution.

  19. UWB communication receiver feedback loop

    Science.gov (United States)

    Spiridon, Alex; Benzel, Dave; Dowla, Farid U.; Nekoogar, Faranak; Rosenbury, Erwin T.

    2007-12-04

    A novel technique and structure that maximizes the extraction of information from reference pulses for UWB-TR receivers is introduced. The scheme efficiently processes an incoming signal to suppress different types of UWB as well as non-UWB interference prior to signal detection. Such a method and system adds a feedback loop mechanism to enhance the signal-to-noise ratio of reference pulses in a conventional TR receiver. Moreover, sampling the second order statistical function such as, for example, the autocorrelation function (ACF) of the received signal and matching it to the ACF samples of the original pulses for each transmitted bit provides a more robust UWB communications method and system in the presence of channel distortions.

  20. Closed loop steam cooled airfoil

    Science.gov (United States)

    Widrig, Scott M.; Rudolph, Ronald J.; Wagner, Gregg P.

    2006-04-18

    An airfoil, a method of manufacturing an airfoil, and a system for cooling an airfoil is provided. The cooling system can be used with an airfoil located in the first stages of a combustion turbine within a combined cycle power generation plant and involves flowing closed loop steam through a pin array set within an airfoil. The airfoil can comprise a cavity having a cooling chamber bounded by an interior wall and an exterior wall so that steam can enter the cavity, pass through the pin array, and then return to the cavity to thereby cool the airfoil. The method of manufacturing an airfoil can include a type of lost wax investment casting process in which a pin array is cast into an airfoil to form a cooling chamber.

  1. Lose Your Loops with Numpy

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Developing in python is fast. Computation, however, can often be another story. Or at least that is how it may seem. When working with arrays and numerical datasets one can subvert many of python’s computational limitations by utilizing numpy. Numpy is python’s standard matrix computation library. Many python users only use numpy to store and generate arrays, failing to utilize one of python’s most powerful computational tools. By leveraging numpy’s ufuncs, aggregation, broadcasting and slicing/masking/indexing functionality one can cut back on slow python loops and increase the speed of their programs by as much as 100x. This talk aims at teaching attendees how to use these tools through toy examples.

  2. Fiber loop ringdown humidity sensor.

    Science.gov (United States)

    Alali, Haifa; Wang, Chuji

    2016-11-01

    An optical fiber relative humidity (RH) sensor based on the evanescent field-fiber loop ringdown (EF-FLRD) technique is demonstrated. The sensor was placed inside a chamber that provides a humidity reference and is monitored by a humidity meter. The presence of moisture in the chamber changes the refractive index of the medium; thus the ringdown time changes due to a change in the EF scattering loss induced in the sensor head. The sensor demonstrated a fast response (∼1  s), high sensitivity, and excellent reproducibility and reversibly. The EF-FLRD sensor can measure RH in a wide dynamic range of 4% to 100% at a constant temperature of 20±1°C.

  3. A Method for Precision Closed-Loop Irrigation Using a Modified PID Control Algorithm

    Science.gov (United States)

    Goodchild, Martin; Kühn, Karl; Jenkins, Malcolm; Burek, Kazimierz; Dutton, Andrew

    2016-04-01

    The benefits of closed-loop irrigation control have been demonstrated in grower trials which show the potential for improved crop yields and resource usage. Managing water use by controlling irrigation in response to soil moisture changes to meet crop water demands is a popular approach but requires knowledge of closed-loop control practice. In theory, to obtain precise closed-loop control of a system it is necessary to characterise every component in the control loop to derive the appropriate controller parameters, i.e. proportional, integral & derivative (PID) parameters in a classic PID controller. In practice this is often difficult to achieve. Empirical methods are employed to estimate the PID parameters by observing how the system performs under open-loop conditions. In this paper we present a modified PID controller, with a constrained integral function, that delivers excellent regulation of soil moisture by supplying the appropriate amount of water to meet the needs of the plant during the diurnal cycle. Furthermore, the modified PID controller responds quickly to changes in environmental conditions, including rainfall events which can result in: controller windup, under-watering and plant stress conditions. The experimental work successfully demonstrates the functionality of a constrained integral PID controller that delivers robust and precise irrigation control. Coir substrate strawberry growing trial data is also presented illustrating soil moisture control and the ability to match water deliver to solar radiation.

  4. Vacuum energy sequestering and graviton loops

    OpenAIRE

    Kaloper, Nemanja; Padilla, Antonio

    2017-01-01

    We recently formulated a local mechanism of vacuum energy sequester. This mechanism automatically removes all matter loop contributions to vacuum energy from the stress energy tensor which sources the curvature. Here we adapt the local vacuum energy sequestering mechanism to also cancel all the vacuum energy loops involving virtual gravitons, in addition to the vacuum energy generated by matter fields alone.

  5. Loop calculus for lattice gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Gambini, R.; Leal, L.; Trias, A.

    1989-05-15

    Hamiltonian calculations are performed using a loop-labeled basis where the full set of identities for the SU(/ital N/) gauge models has been incorporated. The loops are classified as clusterlike structures and the eigenvalue problem leads to a linear set of finite-difference equations easily amenable to numerical treatment. Encouraging results are reported for SU(2) at spatial dimension 2.

  6. Newtonian gravity in loop quantum gravity

    OpenAIRE

    Smolin, Lee

    2010-01-01

    We apply a recent argument of Verlinde to loop quantum gravity, to conclude that Newton's law of gravity emerges in an appropriate limit and setting. This is possible because the relationship between area and entropy is realized in loop quantum gravity when boundaries are imposed on a quantum spacetime.

  7. Design Principles for Closed Loop Supply Chains

    NARCIS (Netherlands)

    H.R. Krikke (Harold); C.P. Pappis (Costas); G.T. Tsoulfas; J.M. Bloemhof-Ruwaard (Jacqueline)

    2001-01-01

    textabstractIn this paper we study design principles for closed loop supply chains. Closed loop supply chains aim at closing material flows thereby limiting emission and residual waste, but also providing customer service at low cost. We study 'traditional' and 'new' design principles known in the

  8. Holonomy loops, spectral triples and quantum gravity

    DEFF Research Database (Denmark)

    Johannes, Aastrup; Grimstrup, Jesper Møller; Nest, Ryszard

    2009-01-01

    We review the motivation, construction and physical interpretation of a semi-finite spectral triple obtained through a rearrangement of central elements of loop quantum gravity. The triple is based on a countable set of oriented graphs and the algebra consists of generalized holonomy loops...

  9. Droplet flows through periodic loop networks

    Science.gov (United States)

    Jeanneret, Raphael; Schindler, Michael; Bartolo, Denis

    2010-11-01

    Numerous microfluidic experiments have revealed non-trivial traffic dynamics when droplets flow through a channel including a single loop. A complex encoding of the time intervals between the droplets is achieved by the binary choices they make as they enter the loop. Very surprisingly, another set of experiments has demonstrated that the addition of a second loop does not increase the complexity of the droplet pattern. Conversely, the second loop decodes the temporal signal encrypted by the first loop [1]. In this talk we show that no first principle argument based on symmetry or conservation laws can account for this unexpected decoding process. Then, to better understand how a loop maps time intervals between droplets, we consider a simplified model which has proven to describe accurately microfluidic droplet flows. Combining numerical simulations and analytical calculations for the dynamic of three droplets travelling through N loops: (i) We show that three different traffic regimes exist, yet none of them yields exact decoding. (ii) We uncover that for a wide class of loop geometry, the coding process is analogous to a Hamiltonian mapping: regular orbits are destabilized in island chains and separatrix. (iii) Eventually, we propose a simple explanation to solve the apparent paradox with the coding/decoding dynamics observed in experiments. [1] M.J. Fuerstman, P. Garstecki, and G.M. Whitesides, Science, 315:828, 2007.

  10. 77 FR 55896 - Notice of Final Federal Agency Actions on Loop 1 in Texas

    Science.gov (United States)

    2012-09-11

    ..., Section 401, Section 319) ; Land and Water Conservation Fund (LWCF) ; Safe Drinking Water Act (SDWA) [42 U... Federal Highway Administration Notice of Final Federal Agency Actions on Loop 1 in Texas AGENCY: Federal..., Texas. Those actions grant licenses, permits, and approvals for the project. DATES: By this notice, the...

  11. Application of ISFETs in closed-loop systems for greenhouses

    Science.gov (United States)

    Gieling, Th. H.; van den Vlekkert, H. H.

    In horticulture, growing in artificial substrates such as rockwool is more and more considered to be a sound alternative to growing in soil. This development enables the opportunity to create closed-loop systems which lower the waste of raw materials and reduce pollution of the environment. Applying closed-loop systems needs precise knowledge of the composition of the recirculating nutrient solution. This paper presents basic principles of a measuring system, which can monitor continuously the concentration of nutrients in water. The system is based on ion-selective field effect transistors (ISFETs). By appropriate calibration, a high accuracy is achieved for pH and potassium measurements in the nutrient solution. An accuracy of better than 10% (mMol/l) has been achieved.

  12. Transient modelling of a natural circulation loop under variable pressure

    Energy Technology Data Exchange (ETDEWEB)

    Vianna, Andre L.B.; Faccini, Jose L.H.; Su, Jian, E-mail: avianna@nuclear.ufrj.br, E-mail: sujian@nuclear.ufrj.br, E-mail: faccini@ien.gov.br [Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. de Termo-Hidraulica Experimental

    2017-07-01

    The objective of the present work is to model the transient operation of a natural circulation loop, which is one-tenth scale in height to a typical Passive Residual Heat Removal system (PRHR) of an Advanced Pressurized Water Nuclear Reactor and was designed to meet the single and two-phase flow similarity criteria to it. The loop consists of a core barrel with electrically heated rods, upper and lower plena interconnected by hot and cold pipe legs to a seven-tube shell heat exchanger of countercurrent design, and an expansion tank with a descending tube. A long transient characterized the loop operation, during which a phenomenon of self-pressurization, without self-regulation of the pressure, was experimentally observed. This represented a unique situation, named natural circulation under variable pressure (NCVP). The self-pressurization was originated in the air trapped in the expansion tank and compressed by the loop water dilatation, as it heated up during each experiment. The mathematical model, initially oriented to the single-phase flow, included the heat capacity of the structure and employed a cubic polynomial approximation for the density, in the buoyancy term calculation. The heater was modelled taking into account the different heat capacities of the heating elements and the heater walls. The heat exchanger was modelled considering the coolant heating, during the heat exchanging process. The self-pressurization was modelled as an isentropic compression of a perfect gas. The whole model was computationally implemented via a set of finite difference equations. The corresponding computational algorithm of solution was of the explicit, marching type, as for the time discretization, in an upwind scheme, regarding the space discretization. The computational program was implemented in MATLAB. Several experiments were carried out in the natural circulation loop, having the coolant flow rate and the heating power as control parameters. The variables used in the

  13. Mass Inflation in the Loop Black Hole

    CERN Document Server

    Brown, Eric G; Modesto, Leonardo

    2011-01-01

    In classical general relativity the Cauchy horizon within a two-horizon black hole is unstable via a phenomenon known as mass inflation, in which the mass parameter (and the spacetime curvature) of the black hole diverges at the Cauchy horizon. Here we study this effect for loop black holes -- quantum gravitationally corrected black holes from loop quantum gravity -- whose construction alleviates the $r=0$ singularity present in their classical counterparts. We use a simplified model of mass inflation, which makes use of the generalized DTR relation, to conclude that the Cauchy horizon of loop black holes indeed results in a curvature singularity similar to that found in classical black holes. The DTR relation is of particular utility in the loop black hole because it does not directly rely upon Einstein's field equations. We elucidate some of the interesting and counterintuitive properties of the loop black hole, and corroborate our results using an alternate model of mass inflation due to Ori.

  14. Feedback Loop Gains and Feedback Behavior (1996)

    DEFF Research Database (Denmark)

    Kampmann, Christian Erik

    2012-01-01

    Linking feedback loops and system behavior is part of the foundation of system dynamics, yet the lack of formal tools has so far prevented a systematic application of the concept, except for very simple systems. Having such tools at their disposal would be a great help to analysts in understanding...... large, complicated simulation models. The paper applies tools from graph theory formally linking individual feedback loop strengths to the system eigenvalues. The significance of a link or a loop gain and an eigenvalue can be expressed in the eigenvalue elasticity, i.e., the relative change...... of an eigenvalue resulting from a relative change in the gain. The elasticities of individual links and loops may be found through simple matrix operations on the linearized system. Even though the number of feedback loops can grow rapidly with system size, reaching astronomical proportions even for modest systems...

  15. Osmotic mechanism of the loop extrusion process

    Science.gov (United States)

    Yamamoto, Tetsuya; Schiessel, Helmut

    2017-09-01

    The loop extrusion theory assumes that protein factors, such as cohesin rings, act as molecular motors that extrude chromatin loops. However, recent single molecule experiments have shown that cohesin does not show motor activity. To predict the physical mechanism involved in loop extrusion, we here theoretically analyze the dynamics of cohesin rings on a loop, where a cohesin loader is in the middle and unloaders at the ends. Cohesin monomers bind to the loader rather frequently and cohesin dimers bind to this site only occasionally. Our theory predicts that a cohesin dimer extrudes loops by the osmotic pressure of cohesin monomers on the chromatin fiber between the two connected rings. With this mechanism, the frequency of the interactions between chromatin segments depends on the loading and unloading rates of dimers at the corresponding sites.

  16. Carrier tracking algorithm based on joint acquisition of frequency locked loop and phase locked loop

    Directory of Open Access Journals (Sweden)

    Gao Kang

    2017-01-01

    Full Text Available Aiming at the problem of frequency step in the frequency lock loop (FLL - phase lock loop (PLL carrier tracking algorithm’s conversion state, presenting an improved algorithm: PLL and FLL joint acquisition to replace the single FLL acquires frequency, and deduce the loop state transition threshold. The simulation results show that the improved algorithm is more stable in the conversion process, and the loop performance is optimized. When the SNR is -10dB, and has the acceleration rate, the tracking loop does not have a frequency step at the time of conversion, achieving the design purpose.

  17. Water

    CSIR Research Space (South Africa)

    Van Wyk, Llewellyn V

    2010-08-01

    Full Text Available , and of the remaining 2,5 percent, some 70 percent is frozen in the polar caps and around 30 percent is present as soil moisture or in underground aquifers. Less than 1 percent is thus accessible for direct use by humans, animals and plants. Consequently... be serviced with harvested water and/or grey water. Conserve and reuse cooling tower water by using efficient systems and strategies. Avoid ?once-through systems? commonly used for evaporation coolers, ice makers, hydraulic equipment, and air compressors...

  18. Water

    Directory of Open Access Journals (Sweden)

    E. Sanmuga Priya

    2017-05-01

    Full Text Available Phytoremediation through aquatic macrophytes treatment system (AMATS for the removal of pollutants and contaminants from various natural sources is a well established environmental protection technique. Water hyacinth (Eichhornia crassipes, a worst invasive aquatic weed has been utilised for various research activities over the last few decades. The biosorption capacity of the water hyacinth in minimising various contaminants present in the industrial wastewater is well studied. The present review quotes the literatures related to the biosorption capacity of the water hyacinth in reducing the concentration of dyestuffs, heavy metals and minimising certain other physiochemical parameters like TSS (total suspended solids, TDS (total dissolved solids, COD (chemical oxygen demand and BOD (biological oxygen demand in textile wastewater. Sorption kinetics through various models, factors influencing the biosorption capacity, and role of physical and chemical modifications in the water hyacinth are also discussed.

  19. Impact of Caribbean cyclones on the detachment of Loop Current anticyclones

    Science.gov (United States)

    Athié, Gabriela; Candela, Julio; Ochoa, José; Sheinbaum, Julio

    2012-03-01

    The western boundary current in the North Atlantic is characterized by an intense flow (reaching 2.5 ms-1, at the surface) that enters the Caribbean Sea through the Lesser Antilles passages, crosses the entire Caribbean and enters the Gulf of Mexico through the Yucatan Channel, where it is known as the Loop Current. A characteristic feature of the Loop Current is eddy-shedding events (i.e., the detachment of large anticyclonic eddies) at irregular intervals. Moored current measurements between January 2005 and July 2009 in the Loop Current, the Yucatan Channel, and the Caribbean coastal waters of Mexico (i.e., the Western Cayman Sea), along with AVISO altimetry, are used to evidence the northward propagation of cyclonic anomalies along the Caribbean coast of Mexico and the marked eastward displacement of the Loop Current at 23°N latitude, just before several anticyclonic eddy shedding events. After entering the Gulf of Mexico, these cyclonic anomalies might initiate or enhance existing Campeche Bank cyclonic eddies, which are related to many of the Loop Current detachment events. Sixteen of the twenty-one detachments that occurred during the study period (76%) are related to the cyclonic eddies in the Western Caribbean Sea; six of them were not reattached again to the Loop Current. Observations, thus, clearly indicate that cyclonic eddies in the Western Cayman Sea contribute significantly to the Loop Current eddy-shedding process, which is complex and in principle not unique.

  20. Loops in exceptional field theory

    Energy Technology Data Exchange (ETDEWEB)

    Bossard, Guillaume [Centre de Physique Théorique, Ecole Polytechnique, CNRS, Université Paris-Saclay,91128 Palaiseau cedex (France); Kleinschmidt, Axel [Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut),Am Mühlenberg 1, DE-14476 Potsdam (Germany); International Solvay Institutes,ULB-Campus Plaine CP231, BE-1050 Brussels (Belgium)

    2016-01-27

    We study certain four-graviton amplitudes in exceptional field theory in dimensions D≥4 up to two loops. As the formulation is manifestly invariant under the U-duality group E{sub 11−D}(ℤ), our resulting expressions can be expressed in terms of automorphic forms. In the low energy expansion, we find terms in the M-theory effective action of type R{sup 4}, ∇{sup 4}R{sup 4} and ∇{sup 6}R{sup 4} with automorphic coefficient functions in agreement with independent derivations from string theory. This provides in particular an explicit integral formula for the exact string theory ∇{sup 6}R{sup 4} threshold function. We exhibit moreover that the usual supergravity logarithmic divergences cancel out in the full exceptional field theory amplitude, within an appropriately defined dimensional regularisation scheme. We also comment on terms of higher derivative order and the role of the section constraint for possible counterterms.

  1. Theory of loop flows and instability

    Science.gov (United States)

    Priest, E. R.

    A preliminary theory for the steady and transient coronal loop flows in solar active regions and their magnetohydrodynamic instability is presented. Siphon flow is shown to be possible in the loops if a pressure difference is maintained between the footpoints, and to account for the presence of cool cores and appearances of only half a loop. The evolution of active region magnetic loops is found to lead to the continual evaporation and draining of the plasma contained within them, particularly as a result of an increase in heating rate. Consideration of static models for thermally isolated loops reveals them to be thermally unstable, implying that in the absence of some atmospheric stabilizing mechanism, the loops must be in a dynamic state of thermal activity. It is shown that kilogauss photospheric fields may be formed by an intense magnetic field instability, with an associated transient downflow which may induce coronal flows at enhanced velocities. Magnetohydrodynamic stability analysis suggests that the major cause of magnetic stability may be line-tying of loop footpoints in the dense photosphere.

  2. Iterative structure of finite loop integrals

    Energy Technology Data Exchange (ETDEWEB)

    Caron-Huot, Simon [Institute for Advanced Study, Princeton, NJ 08540 (United States); Niels Bohr International Academy and Discovery Center, Blegdamsvej 17, Copenhagen 2100 (Denmark); Henn, Johannes M. [Institute for Advanced Study, Princeton, NJ 08540 (United States)

    2014-06-18

    In this paper we develop further and refine the method of differential equations for computing Feynman integrals. In particular, we show that an additional iterative structure emerges for finite loop integrals. As a concrete non-trivial example we study planar master integrals of light-by-light scattering to three loops, and derive analytic results for all values of the Mandelstam variables s and t and the mass m. We start with a recent proposal for defining a basis of loop integrals having uniform transcendental weight properties and use this approach to compute all planar two-loop master integrals in dimensional regularization. We then show how this approach can be further simplified when computing finite loop integrals. This allows us to discuss precisely the subset of integrals that are relevant to the problem. We find that this leads to a block triangular structure of the differential equations, where the blocks correspond to integrals of different weight. We explain how this block triangular form is found in an algorithmic way. Another advantage of working in four dimensions is that integrals of different loop orders are interconnected and can be seamlessly discussed within the same formalism. We use this method to compute all finite master integrals needed up to three loops. Finally, we remark that all integrals have simple Mandelstam representations.

  3. Hexagon Wilson Loop OPE and Harmonic Polylogarithms

    CERN Document Server

    Papathanasiou, Georgios

    2013-01-01

    A recent, integrability-based conjecture in the framework of the Wilson loop OPE for N=4 SYM theory, predicts the leading OPE contribution for the hexagon MHV remainder function and NMHV ratio function to all loops, in integral form. We prove that these integrals evaluate to a particular basis of harmonic polylogarithms, at any order in the weak coupling expansion. The proof constitutes an algorithm for the direct computation of the integrals, which we employ in order to obtain the full (N)MHV OPE contribution in question up to 6 loops, and certain parts of it up to 12 loops. We attach computer-readable files with our results, as well as an algorithm implementation which may be readily used to generate higher-loop corrections. The feasibility of obtaining the explicit kinematical dependence of the first term in the OPE in principle at arbitrary loop order, offers promise for the suitability of this approach as a non-perturbative description of Wilson loops/scattering amplitudes.

  4. Mitotic chromosome compaction via active loop extrusion

    Science.gov (United States)

    Goloborodko, Anton; Imakaev, Maxim; Marko, John; Mirny, Leonid; MIT-Northwestern Team

    During cell division, two copies of each chromosome are segregated from each other and compacted more than hundred-fold into the canonical X-shaped structures. According to earlier microscopic observations and the recent Hi-C study, chromosomes are compacted into arrays of consecutive loops of ~100 kilobases. Mechanisms that lead to formation of such loop arrays are largely unknown. Here we propose that, during cell division, chromosomes can be compacted by enzymes that extrude loops on chromatin fibers. First, we use computer simulations and analytical modeling to show that a system of loop-extruding enzymes on a chromatin fiber self-organizes into an array of consecutive dynamic loops. Second, we model the process of loop extrusion in 3D and show that, coupled with the topo II strand-passing activity, it leads to robust compaction and segregation of sister chromatids. This mechanism of chromosomal condensation and segregation does not require additional proteins or specific DNA markup and is robust against variations in the number and properties of such loop extruding enzymes. Work at NU was supported by the NSF through Grants DMR-1206868 and MCB-1022117, and by the NIH through Grants GM105847 and CA193419. Work at MIT was supported by the NIH through Grants GM114190 R01HG003143.

  5. Steam drum level control studies of a natural circulation multi loop reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rajesh; Contractor, A.D.; Srivastava, Abhishek; Lele, H.G. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Reactor Safety Div.; Vaze, K.K. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Reactor Design and Development Group

    2013-12-15

    The proposed heavy water moderated and light water cooled pressure tube type boiling water reactor works on natural circulation at all power levels. It has parallel inter-connected loops with 452 boiling channels in the main heat transport system configuration. These multiple (four) interconnected loops influence the steam drum level control adversely through the common reactor inlet header. Alternate design studies made earlier for efficient control of SD levels have shown favorable results. This has lead to explore further the present scheme with the compartmentalization of CRIH into four compartments catering to four loops separately. The conventional 3-element level control has been found to be working satisfactorily. The interconnections between ECCS header and inlet header compartments have also increased the safety margin for various LOCA and design basis events. The paper deals with the SD level control aspects for this novel MHT configuration which has been analyzed for various PIEs (Postulated Initiating Events) and found to be satisfactory. (orig.)

  6. Loop variants of the thermophile Rasamsonia emersonii Cel7A with improved activity against cellulose

    DEFF Research Database (Denmark)

    Sørensen, Trine Holst; Skovbo Windahl, Michael; McBrayer, Brett

    2017-01-01

    Cel7A cellobiohydrolases perform processive hydrolysis on one strand of cellulose, which is threaded through the enzyme's substrate binding tunnel. The tunnel structure results from a groove in the catalytic domain, which is covered by a number of loops. These loops have been identified as potent......Cel7A cellobiohydrolases perform processive hydrolysis on one strand of cellulose, which is threaded through the enzyme's substrate binding tunnel. The tunnel structure results from a groove in the catalytic domain, which is covered by a number of loops. These loops have been identified...... from Rasamsonia emersonii had profound effects on both substrate interactions and catalytic efficacy. At room temperature the double mutant N194A/N197A showed strongly reduced substrate affinity with a water-cellulose partitioning coefficient threefold lower than the wild type. Yet, this variant...

  7. Construction of the blowdown and condensation loop

    Energy Technology Data Exchange (ETDEWEB)

    Park, Choon Kyung; Song, Chul Kyung; Cho, Seok; Chun, S. Y.; Chung, Moon Ki

    1997-12-01

    The blowdown and condensation loop (B and C loop) has been constructed to get experimental data for designing the safety depressurization system (SDS) and steam sparger which are considered to implement in the Korea Next Generation Reactor (KNGR). In this report, system description on the B and C loop is given in detail, which includes the drawings and technical specification of each component, instrumentation and control system, and the operational procedures and the results of the performance testing. (author). 7 refs., 11 tabs., 48 figs.

  8. Polyakov loop correlator in perturbation theory

    Science.gov (United States)

    Berwein, Matthias; Brambilla, Nora; Petreczky, Péter; Vairo, Antonio

    2017-07-01

    We study the Polyakov loop correlator in the weak coupling expansion and show how the perturbative series reexponentiates into singlet and adjoint contributions. We calculate the order g7 correction to the Polyakov loop correlator in the short distance limit. We show how the singlet and adjoint free energies arising from the reexponentiation formula of the Polyakov loop correlator are related to the gauge invariant singlet and octet free energies that can be defined in pNRQCD, namely we find that the two definitions agree at leading order in the multipole expansion, but differ at first order in the quark-antiquark distance.

  9. Eigenvalue distributions of Wilson loops

    Energy Technology Data Exchange (ETDEWEB)

    Lohmayer, Robert

    2010-07-01

    In the first part of this thesis, we focus on the distribution of the eigenvalues of the unitary Wilson loop matrix in the two-dimensional case at arbitrary finite N. To characterize the distribution of the eigenvalues, we introduce three density functions (the ''symmetric'', the ''antisymmetric'', and the ''true'' eigenvalue density) which differ at finite N but possess the same infinite-N limit, exhibiting the Durhuus-Olesen phase transition. Using expansions of determinants and inverse determinants in characters of totally symmetric or totally antisymmetric representations of SU(N), the densities at finite N can be expressed in terms of simple sums involving only dimensions and quadratic Casimir invariants of certain irreducible representations of SU(N), allowing for a numerical computation of the densities at arbitrary N to any desired accuracy. We find that the true eigenvalue density, adding N oscillations to the monotonic symmetric density, is in some sense intermediate between the symmetric and the antisymmetric density, which in turn is given by a sum of N delta peaks located at the zeros of the average of the characteristic polynomial. Furthermore, we show that the dependence on N can be made explicit by deriving integral representations for the resolvents associated to the three eigenvalue densities. Using saddle-point approximations, we confirm that all three densities reduce to the Durhuus-Olesen result in the infinite-N limit. In the second part, we study an exponential form of the multiplicative random complex matrix model introduced by Gudowska-Nowak et al. Varying a parameter which can be identified with the area of the Wilson loop in the unitary case, the region of non-vanishing eigenvalue density of the N-dimensional complex product matrix undergoes a topological change at a transition point in the infinite-N limit. We study the transition by a detailed analysis of the average of the

  10. Loop Diuretics in the Treatment of Hypertension.

    Science.gov (United States)

    Malha, Line; Mann, Samuel J

    2016-04-01

    Loop diuretics are not recommended in current hypertension guidelines largely due to the lack of outcome data. Nevertheless, they have been shown to lower blood pressure and to offer potential advantages over thiazide-type diuretics. Torsemide offers advantages of longer duration of action and once daily dosing (vs. furosemide and bumetanide) and more reliable bioavailability (vs. furosemide). Studies show that the previously employed high doses of thiazide-type diuretics lower BP more than furosemide. Loop diuretics appear to have a preferable side effect profile (less hyponatremia, hypokalemia, and possibly less glucose intolerance). Studies comparing efficacy and side effect profiles of loop diuretics with the lower, currently widely prescribed, thiazide doses are needed. Research is needed to fill gaps in knowledge and common misconceptions about loop diuretic use in hypertension and to determine their rightful place in the antihypertensive arsenal.

  11. Force distribution in a semiflexible loop

    CERN Document Server

    Waters, James T

    2016-01-01

    Loops undergoing thermal fluctuations are prevalent in nature. Ring-like or cross-linked polymers, cyclic macromolecules, and protein-mediated DNA loops all belong to this category. Stability of these molecules are generally described in terms of free energy, an average quantity, but it may also be impacted by local fluctuating forces acting within these systems. The full distribution of these forces can thus give us insights into mechanochemistry beyond the predictive capability of thermodynamics. In this paper, we study the force exerted by an inextensible semiflexible polymer constrained in a looped state. By using a novel simulation method termed "phase-space sampling", we generate the equilibrium distribution of chain conformations in both position and momentum space. We compute the constraint forces between the two ends of the loop in this chain ensemble using Lagrangian mechanics, and show that the mean of these forces is equal to the thermodynamic force. By analyzing kinetic and potential contribution...

  12. A theory of desynchronisable closed loop system

    Directory of Open Access Journals (Sweden)

    Harsh Beohar

    2010-10-01

    Full Text Available The task of implementing a supervisory controller is non-trivial, even though different theories exist that allow automatic synthesis of these controllers in the form of automata. One of the reasons for this discord is due to the asynchronous interaction between a plant and its controller in implementations, whereas the existing supervisory control theories assume synchronous interaction. As a consequence the implementation suffer from the so-called inexact synchronisation problem. In this paper we address the issue of inexact synchronisation in a process algebraic setting, by solving a more general problem of refinement. We construct an asynchronous closed loop system by introducing a communication medium in a given synchronous closed loop system. Our goal is to find sufficient conditions under which a synchronous closed loop system is branching bisimilar to its corresponding asynchronous closed loop system.

  13. The Universal One-Loop Effective Action

    CERN Document Server

    Drozd, Aleksandra; Quevillon, Jérémie; You, Tevong

    2016-01-01

    We present the universal one-loop effective action for all operators of dimension up to six obtained by integrating out massive, non-degenerate multiplets. Our general expression may be applied to loops of heavy fermions or bosons, and has been checked against partial results available in the literature. The broad applicability of this approach simplifies one-loop matching from an ultraviolet model to a lower-energy effective field theory (EFT), a procedure which is now reduced to the evaluation of a combination of matrices in our universal expression, without any loop integrals to evaluate. We illustrate the relationship of our results to the Standard Model (SM) EFT, using as an example the supersymmetric stop and sbottom squark Lagrangian and extracting from our universal expression the Wilson coefficients of dimension-six operators composed of SM fields.

  14. Hardware-in-the-Loop Testing

    Data.gov (United States)

    Federal Laboratory Consortium — RTC has a suite of Hardware-in-the Loop facilities that include three operational facilities that provide performance assessment and production acceptance testing of...

  15. Mathematical Modeling of Loop Heat Pipes

    Science.gov (United States)

    Kaya, Tarik; Ku, Jentung; Hoang, Triem T.; Cheung, Mark L.

    1998-01-01

    The primary focus of this study is to model steady-state performance of a Loop Heat Pipe (LHP). The mathematical model is based on the steady-state energy balance equations at each component of the LHP. The heat exchange between each LHP component and the surrounding is taken into account. Both convection and radiation environments are modeled. The loop operating temperature is calculated as a function of the applied power at a given loop condition. Experimental validation of the model is attempted by using two different LHP designs. The mathematical model is tested at different sink temperatures and at different elevations of the loop. Tbc comparison of the calculations and experimental results showed very good agreement (within 3%). This method proved to be a useful tool in studying steady-state LHP performance characteristics.

  16. Nonequilibrium Chromosome Looping via Molecular Slip Links

    Science.gov (United States)

    Brackley, C. A.; Johnson, J.; Michieletto, D.; Morozov, A. N.; Nicodemi, M.; Cook, P. R.; Marenduzzo, D.

    2017-09-01

    We propose a model for the formation of chromatin loops based on the diffusive sliding of molecular slip links. These mimic the behavior of molecules like cohesin, which, along with the CTCF protein, stabilize loops which contribute to organizing the genome. By combining 3D Brownian dynamics simulations and 1D exactly solvable nonequilibrium models, we show that diffusive sliding is sufficient to account for the strong bias in favor of convergent CTCF-mediated chromosome loops observed experimentally. We also find that the diffusive motion of multiple slip links along chromatin is rectified by an intriguing ratchet effect that arises if slip links bind to the chromatin at a preferred "loading site." This emergent collective behavior favors the extrusion of loops which are much larger than the ones formed by single slip links.

  17. Modulation of DNA loop lifetimes by the free energy of loop formation

    CERN Document Server

    Chen, Yi-Ju; Mulligan, Peter; Spakowitz, Andrew J; Phillips, Rob

    2015-01-01

    Storage and retrieval of the genetic information in cells is a dynamic process that requires the DNA to undergo dramatic structural rearrangements. DNA looping is a prominent example of such a structural rearrangement that is essential for transcriptional regulation in both prokaryotes and eukaryotes, and the speed of such regulations affects the fitness of individuals. Here, we examine the in vitro looping dynamics of the classic Lac repressor gene-regulatory motif. We show that both loop association and loop dissociation at the DNA-repressor junctions depend on the elastic deformation of the DNA and protein, and that both looping and unlooping rates approximately scale with the looping J factor, which reflects the system's deformation free energy. We explain this observation by transition state theory and model the DNA-protein complex as an effective worm-like chain with twist. We introduce a finite protein-DNA binding interaction length, in competition with the characteristic DNA deformation length scale, ...

  18. EURISOL-DS METEX: Cooling and Temperature Control of the Mercury Loop

    CERN Document Server

    Stefan Joray

    The cooling of the mercury loop is described on pages two, three and four. The gaps in the water jackets of the heat exchangers are too large and the cooling water capacity is too low. Convection from the wall into water is bad. The mercury temperature is too high. On page five is a proposal how the mercury temperature can be kept low and constant.

  19. Laser welding closed-loop power control

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove

    2003-01-01

    A closed-loop control system is developed to maintain an even seam width on the root side of a laser weld by continually controlling the output laser power of a 1500 W CO2 laser.......A closed-loop control system is developed to maintain an even seam width on the root side of a laser weld by continually controlling the output laser power of a 1500 W CO2 laser....

  20. Design configurations of the methanol synthesis loop

    OpenAIRE

    Bøhn, Kristian

    2011-01-01

    In recent years the chemical industry has undergone considerable changes due to increased environmental regulations and energy costs. This master thesis has evaluated three different design considerations of the methanol synthesis loop using Honeywell's general purpose process simulator UniSim Design (R380 Build 14027) combined with MathWorks programming language MATLAB. The three configurations are Lurgis methanol reactor loop as built on Tjeldbergodden, the use of interstage methanol remova...

  1. Loop residues and catalysis in OMP synthase

    DEFF Research Database (Denmark)

    Wang, Gary P.; Hansen, Michael Riis; Grubmeyer, Charles

    2012-01-01

    (preceding paper in this issue, DOI 10.1021/bi300083p)]. The full expression of KIEs by H105A and E107A may result from a less secure closure of the catalytic loop. The lower level of expression of the KIE by K103A suggests that in these mutant proteins the major barrier to catalysis is successful closure...... of the catalytic loop, which when closed, produces rapid and reversible catalysis....

  2. Multiple Flow Loop SCADA System Implemented on the Production Prototype Loop

    Energy Technology Data Exchange (ETDEWEB)

    Baily, Scott A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalmas, Dale Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wheat, Robert Mitchell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Woloshun, Keith Albert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-16

    The following report covers FY 15 activities to develop supervisory control and data acquisition (SCADA) system for the Northstar Moly99 production prototype gas flow loop. The goal of this effort is to expand the existing system to include a second flow loop with a larger production-sized blower. Besides testing the larger blower, this system will demonstrate the scalability of our solution to multiple flow loops.

  3. Space Station evolution study oxygen loop closure

    Science.gov (United States)

    Wood, M. G.; Delong, D.

    1993-01-01

    In the current Space Station Freedom (SSF) Permanently Manned Configuration (PMC), physical scars for closing the oxygen loop by the addition of oxygen generation and carbon dioxide reduction hardware are not included. During station restructuring, the capability for oxygen loop closure was deferred to the B-modules. As such, the ability to close the oxygen loop in the U.S. Laboratory module (LAB A) and the Habitation A module (HAB A) is contingent on the presence of the B modules. To base oxygen loop closure of SSF on the funding of the B-modules may not be desirable. Therefore, this study was requested to evaluate the necessary hooks and scars in the A-modules to facilitate closure of the oxygen loop at or subsequent to PMC. The study defines the scars for oxygen loop closure with impacts to cost, weight and volume and assesses the effects of byproduct venting. In addition, the recommended scenarios for closure with regard to topology and packaging are presented.

  4. A note on two-loop superloop

    Energy Technology Data Exchange (ETDEWEB)

    Belitsky, A.V., E-mail: Andrei.Belitsky@asu.edu [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States)

    2012-11-15

    We explore the duality between supersymmetric Wilson loop on null polygonal contours in maximally supersymmetric Yang-Mills theory and next-to-maximal helicity violating (NMHV) scattering amplitudes. Earlier analyses demonstrated that the use of a dimensional regulator for ultraviolet divergences, induced due to presence of the cusps on the loop, yields anomalies that break both conformal symmetry and supersymmetry. At one-loop order, these are present only in Grassmann components localized in the vicinity of a single cusp and result in a universal function for any number of sites of the polygon that can be subtracted away in a systematic manner leaving a well-defined supersymmetric remainder dual to corresponding components of the superamplitude. The question remains though whether components which were free from the aforementioned supersymmetric anomaly at leading order of perturbation theory remain so once computed at higher orders. Presently we verify this fact by calculating a particular component of the null polygonal super Wilson loop at two loops restricting the contour kinematics to a two-dimensional subspace. This allows one to perform all computations in a concise analytical form and trace the pattern of cancellations between individual Feynman graphs in a transparent fashion. As a consequence of our consideration we obtain a dual conformally invariant result for the remainder function in agreement with one-loop NMHV amplitudes.

  5. Hybrid Combustion-Gasification Chemical Looping

    Energy Technology Data Exchange (ETDEWEB)

    Herbert Andrus; Gregory Burns; John Chiu; Gregory Lijedahl; Peter Stromberg; Paul Thibeault

    2009-01-07

    For the past several years Alstom Power Inc. (Alstom), a leading world-wide power system manufacturer and supplier, has been in the initial stages of developing an entirely new, ultra-clean, low cost, high efficiency power plant for the global power market. This new power plant concept is based on a hybrid combustion-gasification process utilizing high temperature chemical and thermal looping technology The process consists of the oxidation, reduction, carbonation, and calcination of calcium-based compounds, which chemically react with coal, biomass, or opportunity fuels in two chemical loops and one thermal loop. The chemical and thermal looping technology can be alternatively configured as (i) a combustion-based steam power plant with CO{sub 2} capture, (ii) a hybrid combustion-gasification process producing a syngas for gas turbines or fuel cells, or (iii) an integrated hybrid combustion-gasification process producing hydrogen for gas turbines, fuel cells or other hydrogen based applications while also producing a separate stream of CO{sub 2} for use or sequestration. In its most advanced configuration, this new concept offers the promise to become the technology link from today's Rankine cycle steam power plants to tomorrow's advanced energy plants. The objective of this work is to develop and verify the high temperature chemical and thermal looping process concept at a small-scale pilot facility in order to enable AL to design, construct and demonstrate a pre-commercial, prototype version of this advanced system. In support of this objective, Alstom and DOE started a multi-year program, under this contract. Before the contract started, in a preliminary phase (Phase 0) Alstom funded and built the required small-scale pilot facility (Process Development Unit, PDU) at its Power Plant Laboratories in Windsor, Connecticut. Construction was completed in calendar year 2003. The objective for Phase I was to develop the indirect combustion loop with CO{sub 2

  6. Generic Safety Issue (GSI) 171 -- Engineered Safety Feature (ESF) failure from a loop subsequent to LOCA: Assessment of plant vulnerability and CDF contributions

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Guridi, G.; Samanta, P.; Chu, L.; Yang, J. [Brookhaven National Lab., Upton, NY (United States)

    1998-03-01

    Generic Safety Issue 171 (GSI-171), Engineered Safety Feature (ESF) from a Loss Of Offsite Power (LOOP) subsequent to a Loss Of Coolant Accident (LOCA), deals with an accident sequence in which a LOCA is followed by a LOOP. This issue was later broadened to include a LOOP followed by a LOCA. Plants are designed to handle a simultaneous LOCA and LOOP. In this paper, the authors address the unique issues that are involved i LOCA with delayed LOOP (LOCA/LOOP) and LOOP with delayed LOCA (LOOP/LOCA) accident sequences. LOCA/LOOP accidents are analyzed further by developing event-tree/fault-tree models to quantify their contributions to core-damage frequency (CDF) in a pressurized water reactor and a boiling water reactor (PWR and a BWR). Engineering evaluation and judgments are used during quantification to estimate the unique conditions that arise in a LOCA/LOOP accident. The results show that the CDF contribution of such an accident can be a dominant contributor to plant risk, although BWRs are less vulnerable than PWRs.

  7. Numerical Analysis of General Trends in Single-Phase Natural Circulation in a 2D-Annular Loop

    Directory of Open Access Journals (Sweden)

    Gilles Desrayaud

    2008-01-01

    Full Text Available The aim of this paper is to address fluid flow behavior of natural circulation in a 2D-annular loop filled with water. A two-dimensional, numerical analysis of natural convection in a 2D-annular closed-loop thermosyphon has been performed for various radius ratios from 1.2 to 2.0, the loop being heated at a constant flux over the bottom half and cooled at a constant temperature over the top half. It has been numerically shown that natural convection in a 2D-annular closed-loop thermosyphon is capable of showing pseudoconductive regime at pitchfork bifurcation, stationary convective regimes without and with recirculating regions occurring at the entrance of the exchangers, oscillatory convection at Hopf bifurcation and Lorenz-like chaotic flow. The complexity of the dynamic properties experimentally encountered in toroidal or rectangular loops is thus also found here.

  8. Behavior of a Fully-Looped Drainage Network and the Corresponding Dendritic Networks

    Directory of Open Access Journals (Sweden)

    Yongwon Seo

    2015-03-01

    Full Text Available Hydraulic and hydrologic analysis in urban catchments is typically accompanied by a number of uncertainties, such as a lack of required information for modeling purposes or complex loops inside a drainage network. In this article, Gibbs’ stochastic network model is utilized in order to achieve a dendritic network that corresponds to a fully looped network in terms of the peak of the runoff hydrograph at the outlet. A synthetic catchment with a drainage network composed of 8 × 8 grids is introduced to investigate the behavior of a fully looped network for a given rainfall event using the Storm Water Management Model. Dendritic networks are generated from the Gibbsian model for a given value of the parameter, β. The results showed that the shape of the hydrograph and the peak flow of a fully looped network are heavily dependent on the catchment slope. Moreover, the results showed that it is possible to find the corresponding dendritic networks generated by the Gibbsian model that match the fully looped network depending on the catchment slope in terms of peak flows. The results of this study imply the potential improvement of drainage network analysis providing a relationship between the catchment slope of a fully looped network and the corresponding dendritic network generated by the Gibbsian model.

  9. Complex Inversion of MRT Signals under Different Loop Configurations for Groundwater Exploration.

    Science.gov (United States)

    Chen, Bin; Hu, Xiangyun; Li, Jianhui; Liu, Yajun

    2017-03-01

    Surface nuclear magnetic resonance (SNMR) is a relatively new geophysical method for non-invasive groundwater exploration and aquifer characterization. Conventional SNMR surveys based on one-dimensional (1-D) inversion of amplitude data recorded only using coincident loops provide limited or distorted groundwater distribution information, especially in regions with strong lateral heterogeneity and complicated hydrological environments. The simplistic approach limits the applicability and efficiency of SNMR, which was therefore made more effective in this study using a sophisticated signal response formulation. The elliptical polarization parameters of the excitation magnetic fields and 2-D sensitivity kernels (including real and imaginary parts) of three commonly used loop configurations were first calculated. After all the individual complex signals of five simulated measurement series along a profile were incorporated. The 2-D magnetic resonance tomography (MRT) complex inversion scheme was then used to perform high resolution tomography of synthetic models under the three loop configurations, taking full advantage of the different sensitivity distributions offered by the different loop configurations and the high sensitivity of the imaginary parts of signals to deep structures. Contrast analyses of the tomographic results showed that the complex inversions significantly decreased model ambiguities and increased depth resolution even with artificial noise added. Coincident loop measurements usually gave the best vertical resolution, and separated loops provided better lateral resolution. However, various factors would influence phase data, meaning that the complex inversion of field data is neither very reliable nor very common at present. © 2016, National Ground Water Association.

  10. Students' Understanding of Loops and Nested Loops in Computer Programming: An APOS Theory Perspective

    Science.gov (United States)

    Cetin, Ibrahim

    2015-01-01

    The purpose of this study is to explore students' understanding of loops and nested loops concepts. Sixty-three mechanical engineering students attending an introductory programming course participated in the study. APOS (Action, Process, Object, Schema) is a constructivist theory developed originally for mathematics education. This study is the…

  11. Open-loop versus closed-loop control of MEMS devices: choices and issues

    Science.gov (United States)

    Borovic, B.; Liu, A. Q.; Popa, D.; Cai, H.; Lewis, F. L.

    2005-10-01

    From a controls point of view, micro electromechanical systems (MEMS) can be driven in an open-loop and closed-loop fashion. Commonly, these devices are driven open-loop by applying simple input signals. If these input signals become more complex by being derived from the system dynamics, we call such control techniques pre-shaped open-loop driving. The ultimate step for improving precision and speed of response is the introduction of feedback, e.g. closed-loop control. Unlike macro mechanical systems, where the implementation of the feedback is relatively simple, in the MEMS case the feedback design is quite problematic, due to the limited availability of sensor data, the presence of sensor dynamics and noise, and the typically fast actuator dynamics. Furthermore, a performance comparison between open-loop and closed-loop control strategies has not been properly explored for MEMS devices. The purpose of this paper is to present experimental results obtained using both open- and closed-loop strategies and to address the comparative issues of driving and control for MEMS devices. An optical MEMS switching device is used for this study. Based on these experimental results, as well as computer simulations, we point out advantages and disadvantages of the different control strategies, address the problems that distinguish MEMS driving systems from their macro counterparts, and discuss criteria to choose a suitable control driving strategy.

  12. Quantum hysteresis loops in microscopic system: The loop area as a ...

    Indian Academy of Sciences (India)

    Effects of non-zero temperatures are explored with reference to a symmetric double well potential. The barrier crossing or, relaxation rates are shown to correlate systematically with the area of the loop. The possible use of hysteresis loop area in designing field parameters for optimal control is suggested.

  13. Parameterizing loop fusion for automated empirical tuning

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Y; Yi, Q; Kennedy, K; Quinlan, D; Vuduc, R

    2005-12-15

    Traditional compilers are limited in their ability to optimize applications for different architectures because statically modeling the effect of specific optimizations on different hardware implementations is difficult. Recent research has been addressing this issue through the use of empirical tuning, which uses trial executions to determine the optimization parameters that are most effective on a particular hardware platform. In this paper, we investigate empirical tuning of loop fusion, an important transformation for optimizing a significant class of real-world applications. In spite of its usefulness, fusion has attracted little attention from previous empirical tuning research, partially because it is much harder to configure than transformations like loop blocking and unrolling. This paper presents novel compiler techniques that extend conventional fusion algorithms to parameterize their output when optimizing a computation, thus allowing the compiler to formulate the entire configuration space for loop fusion using a sequence of integer parameters. The compiler can then employ an external empirical search engine to find the optimal operating point within the space of legal fusion configurations and generate the final optimized code using a simple code transformation system. We have implemented our approach within our compiler infrastructure and conducted preliminary experiments using a simple empirical search strategy. Our results convey new insights on the interaction of loop fusion with limited hardware resources, such as available registers, while confirming conventional wisdom about the effectiveness of loop fusion in improving application performance.

  14. Logical inference techniques for loop parallelization

    KAUST Repository

    Oancea, Cosmin E.

    2012-01-01

    This paper presents a fully automatic approach to loop parallelization that integrates the use of static and run-time analysis and thus overcomes many known difficulties such as nonlinear and indirect array indexing and complex control flow. Our hybrid analysis framework validates the parallelization transformation by verifying the independence of the loop\\'s memory references. To this end it represents array references using the USR (uniform set representation) language and expresses the independence condition as an equation, S = Ø, where S is a set expression representing array indexes. Using a language instead of an array-abstraction representation for S results in a smaller number of conservative approximations but exhibits a potentially-high runtime cost. To alleviate this cost we introduce a language translation F from the USR set-expression language to an equally rich language of predicates (F(S) ⇒ S = Ø). Loop parallelization is then validated using a novel logic inference algorithm that factorizes the obtained complex predicates (F(S)) into a sequence of sufficient-independence conditions that are evaluated first statically and, when needed, dynamically, in increasing order of their estimated complexities. We evaluate our automated solution on 26 benchmarks from PERFECTCLUB and SPEC suites and show that our approach is effective in parallelizing large, complex loops and obtains much better full program speedups than the Intel and IBM Fortran compilers. Copyright © 2012 ACM.

  15. Coronal Loops: Observations and Modeling of Confined Plasma

    Directory of Open Access Journals (Sweden)

    Fabio Reale

    2010-11-01

    Full Text Available Coronal loops are the building blocks of the X-ray bright solar corona. They owe their brightness to the dense confined plasma, and this review focuses on loops mostly as structures confining plasma. After a brief historical overview, the review is divided into two separate but not independent parts: the first illustrates the observational framework, the second reviews the theoretical knowledge. Quiescent loops and their confined plasma are considered, and therefore topics such as loop oscillations and flaring loops (except for non-solar ones which provide information on stellar loops are not specifically addressed here. The observational section discusses loop classification and populations, and then describes the morphology of coronal loops, its relationship with the magnetic field, and the concept of loops as multi-stranded structures. The following part of this section is devoted to the characteristics of the loop plasma and of its thermal structure in particular, according to the classification into hot, warm, and cool loops. Then, temporal analyses of loops and the observations of plasma dynamics and flows are illustrated. In the modeling section some basics of loop physics are provided, supplying some fundamental scaling laws and timescales, a useful tool for consultation. The concept of loop modeling is introduced and models are distinguished between those treating loops as monolithic and static, and those resolving loops into thin and dynamic strands. Then, more specific discussions address modeling the loop fine structure and the plasma flowing along the loops. Special attention is devoted to the question of loop heating, with separate discussion of wave (AC and impulsive (DC heating. Finally, a brief discussion about stellar X-ray emitting structures related to coronal loops is included and followed by conclusions and open questions.

  16. BPS Wilson loops and Bremsstrahlung function in ABJ(M): a two loop analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, Marco S. [Institut für Physik, Humboldt-Universität zu Berlin,Newtonstraße 15, 12489 Berlin (Germany); Griguolo, Luca [Dipartimento di Fisica e Scienze della Terra, Università di Parmaand INFN Gruppo Collegato di Parma,Viale G.P. Usberti 7/A, 43100 Parma (Italy); Leoni, Matias [Physics Department, FCEyN-UBA & IFIBA-CONICETCiudad Universitaria, Pabellón I, 1428, Buenos Aires (Argentina); Penati, Silvia [Dipartimento di Fisica, Università di Milano-Bicoccaand INFN, Sezione di Milano-Bicocca,Piazza della Scienza 3, I-20126 Milano (Italy); Seminara, Domenico [Dipartimento di Fisica, Università di Firenzeand INFN Sezione di Firenze,via G. Sansone 1, 50019 Sesto Fiorentino (Italy)

    2014-06-19

    We study a family of circular BPS Wilson loops in N=6 super Chern-Simons-matter theories, generalizing the usual 1/2-BPS circle. The scalar and fermionic couplings depend on two deformation parameters and these operators can be considered as the ABJ(M) counterpart of the DGRT latitudes defined in N=4 SYM. We perform a complete two-loop analysis of their vacuum expectation value, discuss the appearance of framing-like phases and propose a general relation with cohomologically equivalent bosonic operators. We make an all-loop proposal for computing the Bremsstrahlung function associated to the 1/2-BPS cusp in terms of these generalized Wilson loops. When applied to our two-loop result it reproduces the known expression. Finally, we comment on the generalization of this proposal to the bosonic 1/6-BPS case.

  17. Covariant diagrams for one-loop matching

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhengkang [Michigan Univ., Ann Arbor, MI (United States). Michigan Center for Theoretical Physics; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2016-10-15

    We present a diagrammatic formulation of recently-revived covariant functional approaches to one-loop matching from an ultraviolet (UV) theory to a low-energy effective field theory. Various terms following from a covariant derivative expansion (CDE) are represented by diagrams which, unlike conventional Feynman diagrams, involve gaugecovariant quantities and are thus dubbed ''covariant diagrams.'' The use of covariant diagrams helps organize and simplify one-loop matching calculations, which we illustrate with examples. Of particular interest is the derivation of UV model-independent universal results, which reduce matching calculations of specific UV models to applications of master formulas. We show how such derivation can be done in a more concise manner than the previous literature, and discuss how additional structures that are not directly captured by existing universal results, including mixed heavy-light loops, open covariant derivatives, and mixed statistics, can be easily accounted for.

  18. Solar flare loops observations and interpretations

    CERN Document Server

    Huang, Guangli; Ji, Haisheng; Ning, Zongjun

    2018-01-01

    This book provides results of analysis of typical solar events, statistical analysis, the diagnostics of energetic electrons and magnetic field, as well as the global behavior of solar flaring loops such as their contraction and expansion. It pays particular attention to analyzing solar flare loops with microwave, hard X-ray, optical and EUV emissions, as well as the theories of their radiation, and electron acceleration/transport. The results concerning influence of the pitch-angle anisotropy of non-thermal electrons on their microwave and hard X-ray emissions, new spectral behaviors in X-ray and microwave bands, and results related to the contraction of flaring loops, are widely discussed in the literature of solar physics. The book is useful for graduate students and researchers in solar and space physics.

  19. Automated one-loop calculations with GOSAM

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, Gavin [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Greiner, Nicolas [Illinois Univ., Urbana-Champaign, IL (United States). Dept. of Physics; Max-Planck-Institut fuer Physik, Muenchen (Germany); Heinrich, Gudrun; Reiter, Thomas [Max-Planck-Institut fuer Physik, Muenchen (Germany); Luisoni, Gionata [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; Mastrolia, Pierpaolo [Max-Planck-Institut fuer Physik, Muenchen (Germany); Padua Univ. (Italy). Dipt. di Fisica; Ossola, Giovanni [New York City Univ., NY (United States). New York City College of Technology; New York City Univ., NY (United States). The Graduate School and University Center; Tramontano, Francesco [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2011-11-15

    We present the program package GoSam which is designed for the automated calculation of one-loop amplitudes for multi-particle processes in renormalisable quantum field theories. The amplitudes, which are generated in terms of Feynman diagrams, can be reduced using either D-dimensional integrand-level decomposition or tensor reduction. GoSam can be used to calculate one-loop QCD and/or electroweak corrections to Standard Model processes and offers the flexibility to link model files for theories Beyond the Standard Model. A standard interface to programs calculating real radiation is also implemented. We demonstrate the flexibility of the program by presenting examples of processes with up to six external legs attached to the loop. (orig.)

  20. Hybrid Models in Loop Quantum Cosmology

    CERN Document Server

    Navascués, B Elizaga; Marugán, G A Mena

    2016-01-01

    In the framework of Loop Quantum Cosmology, inhomogeneous models are usually quantized by means of a hybrid approach that combines loop quantization techniques with standard quantum field theory methods. This approach is based on a splitting of the phase space in a homogeneous sector, formed by global, zero-modes, and an inhomogeneous sector, formed by the remaining, infinite number of modes, that describe the local degrees of freedom. Then, the hybrid quantization is attained by adopting a loop representation for the homogeneous gravitational sector, while a Fock representation is used for the inhomogeneities. The zero-mode of the Hamiltonian constraint operator couples the homogeneous and inhomogeneous sectors. The hybrid approach, therefore, is expected to provide a suitable quantum theory in regimes where the main quantum effects of the geometry are those affecting the zero-modes, while the inhomogeneities, still being quantum, can be treated in a more conventional way. This hybrid strategy was first prop...

  1. All Digital Phase-Locked Loop

    Directory of Open Access Journals (Sweden)

    Marijan Jurgo

    2013-05-01

    Full Text Available The paper reviews working principles of phase-locked loop and drawbacks of classical PLL structure in nanometric technologies. It is proposed to replace the classical structure by all-digital phase-locked loop structure. Authors described the main blocks of all-digital phase-locked loop (time to digital converter and digitally controlled oscillator and overviewed the quantization noise arising in these blocks as well as its minimization strategies. The calculated inverter delay in 65 nm CMOS technology was from 8.64 to 27.71 ps and time to digital converter quantization noise was from −104.33 to −82.17 dBc/Hz, with tres = 8.64–27.71 ps, TSVG = 143–333 ps, FREF = 20–60 MHz.Article in Lithuanian

  2. High Pressure Fire Loop Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Godwin, Aaron [Texas Tech Univ., Lubbock, TX (United States); Pantex Plant (PTX), Amarillo, TX (United States)

    2017-10-16

    The scope will be limited to analyzing the effect of the EFC within the system and how one improperly installed coupling affects the rest of the HPFL system. The discussion will include normal operations, impaired flow, and service interruptions. Normal operations are defined as two-way flow to buildings. Impaired operations are defined as a building that only has one-way flow being provided to the building. Service interruptions will be when a building does not have water available to it. The project will look at the following aspects of the reliability of the HPFL system: mean time to failure (MTTF) of EFCs, mean time between failures (MTBF), series system models, and parallel system models. These calculations will then be used to discuss the reliability of the system when one of the couplings fails. Compare the reliability of two-way feeds versus one-way feeds.

  3. Coronal Loops: Evolving Beyond the Isothermal Approximation

    Science.gov (United States)

    Schmelz, J. T.; Cirtain, J. W.; Allen, J. D.

    2002-05-01

    Are coronal loops isothermal? A controversy over this question has arisen recently because different investigators using different techniques have obtained very different answers. Analysis of SOHO-EIT and TRACE data using narrowband filter ratios to obtain temperature maps has produced several key publications that suggest that coronal loops may be isothermal. We have constructed a multi-thermal distribution for several pixels along a relatively isolated coronal loop on the southwest limb of the solar disk using spectral line data from SOHO-CDS taken on 1998 Apr 20. These distributions are clearly inconsistent with isothermal plasma along either the line of sight or the length of the loop, and suggested rather that the temperature increases from the footpoints to the loop top. We speculated originally that these differences could be attributed to pixel size -- CDS pixels are larger, and more `contaminating' material would be expected along the line of sight. To test this idea, we used CDS iron line ratios from our data set to mimic the isothermal results from the narrowband filter instruments. These ratios indicated that the temperature gradient along the loop was flat, despite the fact that a more complete analysis of the same data showed this result to be false! The CDS pixel size was not the cause of the discrepancy; rather, the problem lies with the isothermal approximation used in EIT and TRACE analysis. These results should serve as a strong warning to anyone using this simplistic method to obtain temperature. This warning is echoed on the EIT web page: ``Danger! Enter at your own risk!'' In other words, values for temperature may be found, but they may have nothing to do with physical reality. Solar physics research at the University of Memphis is supported by NASA grant NAG5-9783. This research was funded in part by the NASA/TRACE MODA grant for Montana State University.

  4. Coronal Loops: Observations and Modeling of Confined Plasma

    Directory of Open Access Journals (Sweden)

    Fabio Reale

    2014-07-01

    Full Text Available Coronal loops are the building blocks of the X-ray bright solar corona. They owe their brightness to the dense confined plasma, and this review focuses on loops mostly as structures confining plasma. After a brief historical overview, the review is divided into two separate but not independent parts: the first illustrates the observational framework, the second reviews the theoretical knowledge. Quiescent loops and their confined plasma are considered and, therefore, topics such as loop oscillations and flaring loops (except for non-solar ones, which provide information on stellar loops are not specifically addressed here. The observational section discusses the classification, populations, and the morphology of coronal loops, its relationship with the magnetic field, and the loop stranded structure. The section continues with the thermal properties and diagnostics of the loop plasma, according to the classification into hot, warm, and cool loops. Then, temporal analyses of loops and the observations of plasma dynamics, hot and cool flows, and waves are illustrated. In the modeling section, some basics of loop physics are provided, supplying fundamental scaling laws and timescales, a useful tool for consultation. The concept of loop modeling is introduced and models are divided into those treating loops as monolithic and static, and those resolving loops into thin and dynamic strands. More specific discussions address modeling the loop fine structure and the plasma flowing along the loops. Special attention is devoted to the question of loop heating, with separate discussion of wave (AC and impulsive (DC heating. Large-scale models including atmosphere boxes and the magnetic field are also discussed. Finally, a brief discussion about stellar coronal loops is followed by highlights and open questions.

  5. Rational Design of Nanobody80 Loop Peptidomimetics

    DEFF Research Database (Denmark)

    Martin, Charlotte; Moors, Samuel L C; Danielsen, Mia

    2017-01-01

    G protein-coupled receptors (GPCRs) play an important role in many cellular responses; as such, their mechanism of action is of utmost interest. To gain insight into the active conformation of GPCRs, the X-ray crystal structures of nanobody (Nb)-stabilized β2 -adrenergic receptor (β2 AR) have been...... that peptidomimetics of the CDR3 loop might be sufficient for binding to the receptor, inhibiting the interaction of β2 AR with intracellular GPCR interacting proteins (e.g., G proteins). Based on previous crystallographic data, a set of peptidomimetics were synthesized that, similar to the Nb80 CDR3 loop, adopt a β...

  6. On closed loop transient response system identification

    Directory of Open Access Journals (Sweden)

    Christer Dalen

    2016-10-01

    Full Text Available Some methods for transient closed loop step response system identification presented in the literature are reviewed. Interestingly some errors in a method published in the early 80's where propagated into a recently published method. These methods are reviewed and some improved methods are suggested and presented. The methods are compared against each other on some closed loop system examples, e.g. a well pipeline-riser severe-slugging flow regime example, using Monte Carlo simulations for comparison of the methods.

  7. Thermal coupling within LTP dynamics control loop

    Energy Technology Data Exchange (ETDEWEB)

    Nofrarias, M; Garcia Marin, A F; Heinzel, G; Hewitson, M; Danzmann, K [Max-Planck-Institut fuer Gravitationsphysik, Albert Einstein Institut (AEI), Callinstrasse 38, 30167 Hannover (Germany); Lobo, A; Sanjuan, J [Institut de Ciencies de l' Espai (ICE-CSIC), Facultat de Ciencies, Torre C5, 08193 Bellaterra (Spain); Ramos-Castro, J, E-mail: miquel.nofrarias@aei.mpg.d [Departament d' Enginyeria Electronica, UPC, Campus Nord, Edifici C4, Jordi Girona 1-3, 08034 Barcelona (Spain)

    2009-03-01

    The Diagnostic Subsytem in the LISA Technology Package (LTP) on board the LISA Pathfinder mission (LPF) will characterise those external disturbances with a potential impact on the performance of the experiment coming from either thermal, magnetic or charged particles perturbations. A correct design of the experiments to measure these effects in flight requires a closed loop analysis that takes into account the dynamics of the test masses, the force applied by the controllers and those noisy terms (coming from sensing or force noise) that enters into the loop. We describe this analysis in the thermal case and we give a first numerical example of the instrument response to controlled thermal inputs.

  8. Automation of one-loop QCD corrections

    CERN Document Server

    Hirschi, Valentin; Frixione, Stefano; Garzelli, Maria Vittoria; Maltoni, Fabio; Pittau, Roberto

    2011-01-01

    We present the complete automation of the computation of one-loop QCD corrections, including UV renormalization, to an arbitrary scattering process in the Standard Model. This is achieved by embedding the OPP integrand reduction technique, as implemented in CutTools, into the MadGraph framework. By interfacing the tool so constructed, which we dub MadLoop, with MadFKS, the fully automatic computation of any infrared-safe observable at the next-to-leading order in QCD is attained. We demonstrate the flexibility and the reach of our method by calculating the production rates for a variety of processes at the 7 TeV LHC.

  9. Magic spinor product methods in loop integrals

    CERN Document Server

    Ward, B F L

    2011-01-01

    We present an approach to higher point loop integrals using Chinese magic in the virtual loop integration variable. We show, using the five point function in the important e^+e^-\\to f\\bar{f}+\\gamma process for ISR as a pedagogical vehicle, that we get an expression for it directly reduced to one scalar 5-point function and 4-, 3-, and 2- point integrals, thereby avoiding the computation of the usual three tensor 5-pt Passarino-Veltman reduction. We argue that this offers potential for greater numerical stability.

  10. Magic spinor product methods in loop integrals

    Science.gov (United States)

    Ward, B. F. L.

    2011-06-01

    We present an approach to higher point loop integrals using Chinese magic in the virtual loop integration variable. We show, using the five point function in the important e+e-→ff¯+γ process for initial state radiation as a pedagogical vehicle, that we get an expression for it directly reduced to one scalar 5-point function and 4-, 3-, and 2- point integrals, thereby avoiding the computation of the usual three tensor 5-pt Passarino-Veltman reduction. We argue that this offers potential for greater numerical stability.

  11. Tuning OpenACC loop execution

    KAUST Repository

    Feki, Saber

    2017-01-07

    The purpose of this chapter is to help OpenACC developer who is already familiar with the basic and essential directives to further improve his code performance by adding more descriptive clauses to OpenACC loop constructs. At the end of this chapter the reader will: • Have a better understanding of the purpose of the OpenACC loop construct and its associated clauses illustrated with use cases • Use the acquired knowledge in practice to further improve the performance of OpenACC accelerated codes

  12. Minimally doubled fermions at one loop

    Science.gov (United States)

    Capitani, Stefano; Weber, Johannes; Wittig, Hartmut

    2009-10-01

    Minimally doubled fermions have been proposed as a cost-effective realization of chiral symmetry at non-zero lattice spacing. Using lattice perturbation theory at one loop, we study their renormalization properties. Specifically, we investigate the consequences of the breaking of hyper-cubic symmetry, which is a typical feature of this class of fermionic discretizations. Our results for the quark self-energy indicate that the four-momentum undergoes a renormalization which is linearly divergent. We also compute renormalization factors for quark bilinears, construct the conserved vector and axial-vector currents and verify that at one loop the renormalization factors of the latter are equal to one.

  13. High-Order Frequency-Locked Loops

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    In very recent years, some attempts for designing high-order frequency-locked loops (FLLs) have been made. Nevertheless, the advantages and disadvantages of these structures, particularly in comparison with a standard FLL and high-order phase-locked loops (PLLs), are rather unclear. This lack...... study, and its small-signal modeling, stability analysis, and parameter tuning are presented. Finally, to gain insight about advantages and disadvantages of high-order FLLs, a theoretical and experimental performance comparison between the designed second-order FLL and a standard FLL (first-order FLL...

  14. Geometric structures on loop and path spaces

    Indian Academy of Sciences (India)

    in M. This is naturally a Fréchet manifold. The tangent space to L(M) at a loop γ is. Tγ L(M) ∼= (S1,γ∗TM). The loop space L(M) is equipped with a natural section of its tangent bundle defined as ξ: L(M) → T L(M) γ ↦→ γ . Whenever we fix a Riemannian metric g on M, we can define an associated weak metric on the space of ...

  15. A keyboard control method for loop measurement

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Z.W. [Universita Degli Studi di Roma La Sapienza (Italy)

    1994-12-31

    This paper describes a keyboard control mode based on the DEC VAX computer. The VAX Keyboard code can be found under running of a program was developed. During the loop measurement or multitask operation, it ables to be distinguished from a keyboard code to stop current operation or transfer to another operation while previous information can be held. The combining of this mode, the author successfully used one key control loop measurement for test Dual Input Memory module which is used in a rearrange Energy Trigger system for LEP 8 Bunch operation.

  16. Fundamental and Harmonic Oscillations in Neighboring Coronal Loops

    Science.gov (United States)

    Li, Hongbo; Liu, Yu; Vai Tam, Kuan

    2017-06-01

    We present observations of multimode (fundamental and harmonic) oscillations in a loop system, which appear to be simultaneously excited by a GOES C-class flare. Analysis of the periodic oscillations reveals that (1) the primary loop with a period of P a ≈ 4 minutes and a secondary loop with two periods of P a ≈ 4 minutes and P b ≈ 2 minutes are detected simultaneously in closely spaced loop strands; (2) both oscillation components have their peak amplitudes near the loop apex, while in the second loop the low-frequency component P a dominates in a loop segment that is two times larger than the high-frequency component P b ; (3) the harmonic mode P b shows the largest deviation from a sinusoidal loop shape at the loop apex. We conclude that multiple harmonic modes with different displacement profiles can be excited simultaneously even in closely spaced strands, similar to the overtones of a violin string.

  17. Transient analysis of subcritical/supercritical carbon dioxide based natural circulation loop with end heat exchangers: experimental study

    Science.gov (United States)

    Yadav, Ajay Kumar; Ramgopal, Maddali; Bhattacharyya, Souvik

    2017-09-01

    Carbon dioxide (CO2) based natural circulation loops (NCLs) has gained attention due to its compactness with higher heat transfer rate. In the present study, experimental investigations have been carried out to capture the transient behaviour of a CO2 based NCL operating under subcritical as well as supercritical conditions. Water is used as the external fluid in cold and hot heat exchangers. Results are obtained for various inlet temperatures (323-353 K) of water in the hot heat exchanger and a fixed inlet temperature (305 K) of cooling water in the cold heat exchanger. Effect of loop operating pressure (50-90 bar) on system performance is also investigated. Effect of loop tilt in two different planes (XY and YZ) is also studied in terms of transient as well as steady state behaviour of the loop. Results show that the time required to attain steady state decreases as operating pressure of the loop increases. It is also observed that the change in temperature of loop fluid (CO2) across hot or cold heat exchanger decreases as operating pressure increases.

  18. Evaluation and Comparison of Biomechanical Properties of Snail Loop with that of Opus Loop and Teardrop Loop for en masse Retraction of Anterior Teeth: FEM Study

    Directory of Open Access Journals (Sweden)

    Parikshit Rajkumar Rao

    2013-01-01

    Results: Inherently the M/F ratio produced was higher and F/D rate produced was least for opus loop compared to snail loop and teardrop loop. Conclusion: With incorporation of 20°gable bends snail loop prepared in 0.017 × 0.025 inch and 0.019 × 0.025 inch TMA wire is very efficient to deliver M/F ratio required for translatory tooth movement with acceptable F/D rate. Snail loop is easy to fabricate and finer shape morphology prevents tissue impingement.

  19. Logical inference techniques for loop parallelization

    DEFF Research Database (Denmark)

    Oancea, Cosmin Eugen; Rauchwerger, Lawrence

    2012-01-01

    of their estimated complexities. We evaluate our automated solution on 26 benchmarks from PERFECT-CLUB and SPEC suites and show that our approach is effective in parallelizing large, complex loops and obtains much better full program speedups than the Intel and IBM Fortran compilers....

  20. Loop quantum gravity; Gravedad cuantica de lazos

    Energy Technology Data Exchange (ETDEWEB)

    Pullin, J.

    2015-07-01

    Loop quantum gravity is one of the approaches that are being studied to apply the rules of quantum mechanics to the gravitational field described by the theory of General Relativity . We present an introductory summary of the main ideas and recent results. (Author)

  1. Phase locked loops design, simulation, and applications

    CERN Document Server

    Best, Roland E

    2007-01-01

    The Definitive Introduction to Phase-Locked Loops, Complete with Software for Designing Wireless Circuits! The Sixth Edition of Roland Best's classic Phase-Locked Loops has been updated to equip you with today's definitive introduction to PLL design, complete with powerful PLL design and simulation software written by the author. Filled with all the latest PLL advances, this celebrated sourcebook now includes new chapters on frequency synthesis…CAD for PLLs…mixed-signal PLLs…all-digital PLLs…and software PLLs_plus a new collection of sample communications applications. An essential tool for achieving cutting-edge PLL design, the Sixth Edition of Phase-Locked Loops features: A wealth of easy-to-use methods for designing phase-locked loops Over 200 detailed illustrations New to this edition: new chapters on frequency synthesis, including fractional-N PLL frequency synthesizers using sigma-delta modulators; CAD for PLLs, mixed-signal PLLs, all-digital PLLs, and software PLLs; new PLL communications ap...

  2. Closed Loop System Identification with Genetic Algorithms

    Science.gov (United States)

    Whorton, Mark S.

    2004-01-01

    High performance control design for a flexible space structure is challenging since high fidelity plant models are di.cult to obtain a priori. Uncertainty in the control design models typically require a very robust, low performance control design which must be tuned on-orbit to achieve the required performance. Closed loop system identi.cation is often required to obtain a multivariable open loop plant model based on closed-loop response data. In order to provide an accurate initial plant model to guarantee convergence for standard local optimization methods, this paper presents a global parameter optimization method using genetic algorithms. A minimal representation of the state space dynamics is employed to mitigate the non-uniqueness and over-parameterization of general state space realizations. This control-relevant system identi.cation procedure stresses the joint nature of the system identi.cation and control design problem by seeking to obtain a model that minimizes the di.erence between the predicted and actual closed-loop performance.

  3. Aesthetic rehabilitation with multiple loop connectors

    Directory of Open Access Journals (Sweden)

    Ashish Kalra

    2013-01-01

    Full Text Available Patients with a missing tooth along with diastema have limited treatment options to restore the edentulous space. The use of a conventional fixed partial denture (FPD to replace the missing tooth may result in too wide anterior teeth leading to poor esthetics. The diastema resulting from the missing central incisors can be managed with implant-supported prosthesis or FPD with loop connectors. An old lady reported with chief complaints of missing upper anterior teeth due to trauma. Her past dental history revealed that she was having generalized spacing between her upper anterior teeth. Considering her esthetic requirement of maintaining the diastema between 12, 11, 22, and 21, the treatment option of 06 units porcelain fused to metal FPD from canine to canine with intermittent loop connectors between 21, 22, 11, 12 was planned. Connectors basically link different parts of FPDs. The modified FPD with loop connectors enhanced the natural appearance of the restoration, maintained the diastemas and the proper emergence profile, and preserve the remaining tooth structure of abutment teeth. This clinical report discussed a method for fabrication of a modified FPD with loop connectors to restore the wide span created by missing central incisors.

  4. String loop corrected hypermultiplet moduli spaces

    NARCIS (Netherlands)

    Robles-Llana, D.; Saueressig, Frank; Vandoren, S.

    2006-01-01

    Using constraints from supersymmetry and string perturbation theory, we determine the string loop corrections to the hypermultiplet moduli space of type II strings compactified on a generic Calabi-Yau threefold. The corresponding quaternion-Kähler manifolds are completely encoded in terms of a

  5. Semiclassical analysis of loop quantum gravity

    Energy Technology Data Exchange (ETDEWEB)

    Conrady, F.

    2005-10-17

    In this Ph.D. thesis, we explore and develop new methods that should help in determining an effective semiclassical description of canonical loop quantum gravity and spin foam gravity. A brief introduction to loop quantum gravity is followed by three research papers that present the results of the Ph.D. project. In the first article, we deal with the problem of time and a new proposal for implementing proper time as boundary conditions in a sum over histories: we investigate a concrete realization of this formalism for free scalar field theory. In the second article, we translate semiclassical states of linearized gravity into states of loop quantum gravity. The properties of the latter indicate how semiclassicality manifests itself in the loop framework, and how this may be exploited for doing semiclassical expansions. In the third part, we propose a new formulation of spin foam models that is fully triangulation- and background-independent: by means of a symmetry condition, we identify spin foam models whose triangulation-dependence can be naturally removed. (orig.)

  6. Introduction to Loop Quantum Gravity and Cosmology

    Science.gov (United States)

    Ashtekar, Abhay

    The goal of the lecture is to present a broad perspective on loop quantum gravity and cosmology for young researchers which would serve as an introduction to lectures by Rovelli and Bojowald. The first part is addressed to beginning students and the second to young researchers who are already working in quantum gravity.

  7. Closing the loop: towards strategic defence management

    NARCIS (Netherlands)

    de Spiegeleire, S.; van Hooft, P.; Culpepper, C.; Willems, R.

    2009-01-01

    How do defence-organisations (or organisations with comparable profiles) of other countries map out policy goals and how are policy goals related to activities and capabilities and the required financial means, and finally how does the feedback loop on the performance in all these areas take place?

  8. Closed-loop control of magnetotactic bacteria

    NARCIS (Netherlands)

    Khalil, I.S.M.; Pichel, Marc Philippe; Pichel, M.P.; Abelmann, Leon; Misra, Sarthak

    Realization of point-to-point positioning of a magnetotactic bacterium (MTB) necessitates the application of a relatively large magnetic field gradients to decrease its velocity in the vicinity of a reference position. We investigate an alternative closed-loop control approach to position the MTB.

  9. Geometry of the analytic loop group

    NARCIS (Netherlands)

    De Concini, C.; Hernandez, D.; Reshetikhin, N.

    2013-01-01

    We introduce and study a notion of analytic loop group with a Riemann-Hilbert factorization relevant for the representation theory of quantum affine algebras at roots of unity View the MathML source with non-trivial central charge. We introduce a Poisson structure and study properties of its Poisson

  10. Selective purge for hydrogenation reactor recycle loop

    Science.gov (United States)

    Baker, Richard W.; Lokhandwala, Kaaeid A.

    2001-01-01

    Processes and apparatus for providing improved contaminant removal and hydrogen recovery in hydrogenation reactors, particularly in refineries and petrochemical plants. The improved contaminant removal is achieved by selective purging, by passing gases in the hydrogenation reactor recycle loop or purge stream across membranes selective in favor of the contaminant over hydrogen.

  11. Thermal instabilities in magnetically confined plasmas - Solar coronal loops

    Science.gov (United States)

    Habbal, S. R.; Rosner, R.

    1979-01-01

    The thermal stability of confined solar coronal structures ('loops') is investigated, following both normal mode and a new, global instability analysis. It is demonstrated that: (1) normal mode analysis shows modes with size scales comparable to that of loops to be unstable, but to be strongly affected by the loop boundary conditions; (2) a global analysis, based upon variation of the total loop energy losses and gains, yields loop stability conditions for global modes dependent upon the coronal loop heating process, with magnetically coupled heating processes giving marginal stability. The connection between the present analysis and the minimum flux corona of Hearn is also discussed.

  12. Loop Evolution Observed with AIA and Hi-C

    Science.gov (United States)

    Mulu-Moore, Fana; Winebarger, Amy R.; Cirtain, Jonathan W.; Kobayashi, Ken; Korreck, Kelly E.; Golub, Leon; Kuzin, Sergei; Walsh, Robert William; DeForest, Craig E.; De Pontieu, Bart; hide

    2012-01-01

    In the past decade, the evolution of EUV loops has been used to infer the loop substructure. With the recent launch of High Resolution Coronal Imager (Hi-C), this inference can be validated. In this presentation we discuss the first results of loop analysis comparing AIA and Hi-C data. In the past decade, the evolution of EUV loops has been used to infer the loop substructure. With the recent launch of High Resolution Coronal Imager (Hi-C), this inference can be validated. In this presentation we discuss the first results of loop analysis comparing AIA and Hi-C data.

  13. Method for carrying out biotechnological processes by means of a multi-phase system in a loop reactor.

    NARCIS (Netherlands)

    Tramper, J.

    1987-01-01

    A method for carrying out biotechnological processes by means of multiphase system in a loop reactor, which system comprises an aqueous phase (11) and at least one organic solvent (9, 10) which is immiscible with water and which has a different density from water; one of the liquid components is

  14. Advanced Oxidation Technology for Potable Water Disinfection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The availability of high-quality potable water is essential in crewed space missions. Closed loop water recycling systems as well as potable water holding tanks and...

  15. ORION Environmental Control and Life Support Systems Suit Loop and Pressure Control Analysis

    Science.gov (United States)

    Eckhardt, Brad; Conger, Bruce; Stambaugh, Imelda C.

    2015-01-01

    Under NASA's ORION Multi-Purpose Crew Vehicle (MPCV) Environmental Control and Life Support System (ECLSS) Project at Johnson Space Center's (JSC), the Crew and Thermal Systems Division has developed performance models of the air system using Thermal Desktop/FloCAD. The Thermal Desktop model includes an Air Revitalization System (ARS Loop), a Suit Loop, a Cabin Loop, and Pressure Control System (PCS) for supplying make-up gas (N2 and O2) to the Cabin and Suit Loop. The ARS and PCS are designed to maintain air quality at acceptable O2, CO2 and humidity levels as well as internal pressures in the vehicle Cabin and during suited operations. This effort required development of a suite of Thermal Desktop Orion ECLSS models to address the need for various simulation capabilities regarding ECLSS performance. An initial highly detailed model of the ARS Loop was developed in order to simulate rapid pressure transients (water hammer effects) within the ARS Loop caused by events such as cycling of the Pressurized Swing Adsorption (PSA) Beds and required high temporal resolution (small time steps) in the model during simulation. A second ECLSS model was developed to simulate events which occur over longer periods of time (over 30 minutes) where O2, CO2 and humidity levels, as well as internal pressures needed to be monitored in the cabin and for suited operations. Stand-alone models of the PCS and the Negative Pressure relief Valve (NPRV) were developed to study thermal effects within the PCS during emergency scenarios (Cabin Leak) and cabin pressurization during vehicle re-entry into Earth's atmosphere. Results from the Orion ECLSS models were used during Orion Delta-PDR (July, 2014) to address Key Design Requirements (KDR's) for Suit Loop operations for multiple mission scenarios.

  16. Flow and Heat Transfer Characteristics in a Closed-Type Two-Phase Loop Thermosyphon

    Science.gov (United States)

    Imura, Hideaki; Saito, Yuji; Fujimoto, Hiromitsu

    A closed-loop two-phase thermosyphon can transport a large amount of thermal energy with small temperature differences without any external power supply. A fundamental investigation of flow and heat transfer characteristics was performed experimentally and theoretically using water, ethanol and R113 as the working liquids. Heat transfer coefficients in an evaporator and a condenser, and circulation flow rates were measured experimentally. The effects of liquid fill charge, rotation angle, pressure in the loop and heat flux on the heat transfer coefficients were examined. The heat transfer coefficients in the evaporator and the condenser were correlated by the expressions for pool boiling and film condensation respectively. As a result, the heat transfer coefficients in the evaporator were correlated by the Stephan-Abdelsalam equations within a±40% error. Theoretically, the circulation flow rate was predicted by calculating pressure, temperature, quality and void fraction along the loop. And, the comparison between the calculated and experimental results was made.

  17. Porous Foam Based Wick Structures for Loop Heat Pipes

    Science.gov (United States)

    Silk, Eric A.

    2012-01-01

    As part of an effort to identify cost efficient fabrication techniques for Loop Heat Pipe (LHP) construction, NASA Goddard Space Flight Center's Cryogenics and Fluids Branch collaborated with the U.S. Naval Academy s Aerospace Engineering Department in Spring 2012 to investigate the viability of carbon foam as a wick material within LHPs. The carbon foam was manufactured by ERG Aerospace and machined to geometric specifications at the U.S. Naval Academy s Materials, Mechanics and Structures Machine Shop. NASA GSFC s Fractal Loop Heat Pipe (developed under SBIR contract #NAS5-02112) was used as the validation LHP platform. In a horizontal orientation, the FLHP system demonstrated a heat flux of 75 Watts per square centimeter with deionized water as the working fluid. Also, no failed start-ups occurred during the 6 week performance testing period. The success of this study validated that foam can be used as a wick structure. Furthermore, given the COTS status of foam materials this study is one more step towards development of a low cost LHP.

  18. A Variable-Output Bio-Electrochemical System for Wastewater Treatment and Increased Loop Closure in Exploration Life Support Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this project IntAct Labs proposes to develop a novel system to increase loop closure for water treatment in regenerative life support using bio-electrochemical...

  19. The N-Reactor fuel testing program in the KER loops

    Energy Technology Data Exchange (ETDEWEB)

    Evans, T.W.

    1963-04-01

    The KER loops are four pressurized water-cooled in-reactor testing loops in which fuel, coolant and corrosion tests are being conducted for the N Reactor program. Two of the loops, KER-3 and KER-4, are equipped with N-size Zr-2 process tubes and have sufficient pumping and heat dissipation capacity to permit testing of 14-element charges of N fuel. The other two loops, HER-1 and KER-2, are fitted with Zr-2 process tubes of 2.1 in. inner diameter (vs 2.7 in. for N). The small loops can be used to test charges of N inner tubes or other elements sized at about 1.8 in. outer diameter or less. An inert sleeve must be used with N inner tubes to assure adequate coolant flow over both surfaces of the elements. The KE reactor active zone is 28 in. long com pared to 35 in. for N so the length of test charges is somewhat shorter than actual N charges will be. The purpose of this report is to review the testing environment, to discuss the testing program and to present the schedule as presently seen.

  20. Vapor Compressor Driven Hybrid Two-Phase Loop Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will demonstrate a vapor compressor driven hybrid two-phase loop technology. The hybrid two-phase loop...

  1. Multi-loop calculations: numerical methods and applications

    Science.gov (United States)

    Borowka, S.; Heinrich, G.; Jahn, S.; Jones, S. P.; Kerner, M.; Schlenk, J.

    2017-11-01

    We briefly review numerical methods for calculations beyond one loop and then describe new developments within the method of sector decomposition in more detail. We also discuss applications to two-loop integrals involving several mass scales.

  2. Stability in Real Food Webs: Weak Links in Long Loops

    National Research Council Canada - National Science Library

    Anje-Margriet Neutel; Johan A. P. Heesterbeek; Peter C. de Ruiter

    2002-01-01

    ... of these patterns, how they come about, and why they influence stability. We show that in real food webs, interaction strengths are organized in trophic loops in such a way that long loops contain relatively many weak links...

  3. The Seasonality Of The Loop Current

    Science.gov (United States)

    Hall, Cody Alan

    A total of 20 Loop Current eddy separation event dates were derived from Seasat and ERS-1 satellite altimetry, Coastal Zone Color Scanner chlorophyll-a images, Advanced Very High Resolution Radiometer sea surface temperature images, Horizon Marine, Inc. EddyWatch(TM) reports, and Climatology and Simulation of Eddies Eddy Joint Industry Project Gulf Eddy Model analyses spanning mid-1978 - 1992. There were many inconsistencies between the new "pre-altimetry" reanalysis dates derived from mostly non-altimeter data and dates published in past literature based on earlier versions of the pre-altimetry record. The reanalysis dates were derived from a larger compilation of data types and, consequently, were not as affected by intermittent and seasonal data outages common with past records. Therefore, the reanalysis dates are likely more accurate. About 30 Loop Current eddy separation dates were derived from altimetry data spanning 1993 -- 2012. The pre-altimetry and altimetry reanalysis dates along with similar altimetry dates published in other literature exhibit statistically significant seasonality. Eddy separation events are more likely in the months March, August, and September, and less likely in December. Reanalysis event dates were objectively divided into "spring" and "fall" seasons using a k-means clustering algorithm. The estimated spring and fall season centers are March 2nd and August 23 rd, respectively, with seasonal boundaries on May 22nd and December 3rd. The altimetry data suggest that Loop Current intrusion/retreat is dominantly an annual process. Loop Current metrics such as maximum northern boundary latitude and area are relatively high from January through about July and low in September and October. February metrics are statistically different than metrics in either October or November or both. This annual process is primarily driven by and dynamically linked to geostrophic currents seaward of the Campeche Bank shelf break forced by Kelvin waves

  4. Magnetic Monopoles and the Loop Group.

    Science.gov (United States)

    Norbury, Paul Timothy

    My thesis relates three major works in gauge theory and geometry. I use a technique involving jumping lines in the study of holomorphic bundles over the projective plane to gain information about the loop group and hyperbolic monopoles. I also turn this around and get some information on the jumping lines of a holomorphic bundle. Hurtubise studied the local geometry of a holomorphic bundle on the projective plane around a jumping line, encoding this information into the Toeplitz space. Milgram identified a stratum of the projectivized Toeplitz space with a quotient of the space of rational maps from the two-sphere to itself. I associate the Toeplitz space to the loop group and use Milgram's result to get a description of a stratum of the loop group. By studying their jumping lines I construct those holomorphic bundles on the projective plane which are invariant under a circle action so in particular correspond to hyperbolic monopoles. Again I use Milgram's result to get a new proof of the theorem of Atiyah where he obtains a homeomorphism between the space of hyperbolic monopoles and the space of rational maps from the two-sphere to itself that fix infinity. Conversely using Atiyah's theorem I get a new proof of Milgram's result. This equivalence between the theorems of Milgram and Atiyah generalises to the case of higher rank so I get new results on the local geometry of jumping lines of a holomorphic bundle over the projective plane. There are two main ways to describe holomorphic bundles over the projective plane. Using the loop group I produce a third way to describe such bundles. With this description I show that there is a deeper equivalence between the theorems of Milgram and Atiyah. This work originated from questions about the relationship between the instantons of two dynamical theories --gauge theory over the four-sphere and holomorphic curves in the loop group. I study the gradient flows of the energy functional on the loop group and show how they

  5. Closed-loop fiber optic gyroscope with homodyne detection

    Science.gov (United States)

    Zhu, Yong; Qin, BingKun; Chen, Shufen

    1996-09-01

    Interferometric fiber optic gyroscope (IFOG) has been analyzed with autocontrol theory in this paper. An open-loop IFOG system is not able to restrain the bias drift, but a closed-loop IFOG system can do it very well using negative feedback in order to suppress zero drift. The result of our theoretic analysis and computer simulation indicate that the bias drift of a closed-loop system is smaller than an open- loop one.

  6. Polyakov loops, Gross-Witten like point and Hagedorn states

    OpenAIRE

    Zakout, I.; Greiner, C.

    2011-01-01

    The phase transition for a finite volume system that incorporates the Polyakov loops and maintains the colorless state is explored using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model. The order parameter for Polyakov loops is demonstrated to signal the appearance of a transition for $SU(3)_{c}$ analogous to Gross-Witten (GW-) phase transition instead of the deconfinement phase transition to quark-gluon plasma. The asymptotic restoration of Polyakov loops is conjectured to be a th...

  7. Loop-loop interactions govern multiple steps in indole-3-glycerol phosphate synthase catalysis.

    Science.gov (United States)

    Zaccardi, Margot J; O'Rourke, Kathleen F; Yezdimer, Eric M; Loggia, Laura J; Woldt, Svenja; Boehr, David D

    2014-03-01

    Substrate binding, product release, and likely chemical catalysis in the tryptophan biosynthetic enzyme indole-3-glycerol phosphate synthase (IGPS) are dependent on the structural dynamics of the β1α1 active-site loop. Statistical coupling analysis and molecular dynamic simulations had previously indicated that covarying residues in the β1α1 and β2α2 loops, corresponding to Arg54 and Asn90, respectively, in the Sulfolobus sulfataricus enzyme (ssIGPS), are likely important for coordinating functional motions of these loops. To test this hypothesis, we characterized site mutants at these positions for changes in catalytic function, protein stability and structural dynamics for the thermophilic ssIGPS enzyme. Although there were only modest changes in the overall steady-state kinetic parameters, solvent viscosity and solvent deuterium kinetic isotope effects indicated that these amino acid substitutions change the identity of the rate-determining step across multiple temperatures. Surprisingly, the N90A substitution had a dramatic effect on the general acid/base catalysis of the dehydration step, as indicated by the loss of the descending limb in the pH rate profile, which we had previously assigned to Lys53 on the β1α1 loop. These changes in enzyme function are accompanied with a quenching of ps-ns and µs-ms timescale motions in the β1α1 loop as measured by nuclear magnetic resonance studies. Altogether, our studies provide structural, dynamic and functional rationales for the coevolution of residues on the β1α1 and β2α2 loops, and highlight the multiple roles that the β1α1 loop plays in IGPS catalysis. Thus, substitution of covarying residues in the active-site β1α1 and β2α2 loops of indole-3-glycerol phosphate synthase results in functional, structural, and dynamic changes, highlighting the multiple roles that the β1α1 loop plays in enzyme catalysis and the importance of regulating the structural dynamics of this loop through noncovalent

  8. Geothermal Loop Experimental Facility. Quarterly report, April--June 1978

    Energy Technology Data Exchange (ETDEWEB)

    Bischoff, W.S.; Bishop, H.K.; Cooney, C.S.; Hanenburg, W.H.; Hoaglin, G.J.; Jacobson, W.O.; Mulliner, D.K.; Newell, D.G.; Swanson, C.R.

    1978-07-01

    The Geothermal Loop Experimental Facility (GLEF) was modified to use a two stage flash process with two parallel flash trains for the extraction of energy from a high temperature, high salinity, liquid-dominated resource. Since plant start-up in May 1976, a substantial amount of information has been obtained on the operation of the plant, components, brine and steam composition, production and injection wells, and the potential of the Niland Reservoir. The general operation and accomplishments of the GLEF during the period April 1978 through June 1978 are discussed. The GLEF underwent a major redesign. Modifications and inspections of various GLEF equipment and systems are also discussed. Information about the production and injection wells flow testing and instrumentation are discussed. Information regarding coatings and linings for valves and piping is included. In the Chemistry Section there is a wide range of data taken from Brine, Steam, Scale, Binary, Condensate, and Cooling Water Systems.

  9. The autoregulatory loop: A common mechanism of regulation of key ...

    Indian Academy of Sciences (India)

    ... an autoregulatory positive feedback loop. In this review, by taking examples from various insects, we propose the hypothesis that autoregulatory loop mechanisms of sex determination might be a general strategy. We also discuss the possible reasons for the evolution of autoregulatory loops in sex determination cascades ...

  10. Rare Case of Double Looped Ansa Cervicalis Associated with its ...

    African Journals Online (AJOL)

    fibers of C1‑C3 nerves arose from this loop and ran obliquely downwards superficial to CCA and branched out to supply the infrahyoid muscles. Rare Case of Double Looped Ansa ... Keywords: Ansa cervicalis, Double loop, Nerve muscle transplant, Variation ... categorized as type 3 with the prevalence of 4% and double.

  11. Closed-Loop Optimal Control Implementations for Space Applications

    Science.gov (United States)

    2016-12-01

    COVERED Master’s thesis , Jan-Dec 2016 4. TITLE AND SUBTITLE CLOSED-LOOP OPTIMAL CONTROL IMPLEMENTATIONS FOR SPACE APPLICATIONS 5. FUNDING NUMBERS... Mechanical and Aerospace Engineering iv THIS PAGE INTENTIONALLY LEFT BLANK v ABSTRACT This thesis explores concepts for a closed-loop optimal...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release. Distribution is unlimited. CLOSED-LOOP

  12. Modulation of RNA polymerase activity through trigger loop folding

    OpenAIRE

    Miropolskaya, Nataliya; Nikiforov, Vadim; Klimašauskas, Saulius; Artsimovitch, Irina; Kulbachinskiy, Andrey

    2010-01-01

    Folding of the trigger loop of RNA polymerase promotes nucleotide addition through creating a closed, catalytically competent conformation of the active center. Here, we discuss the impact of adjacent RNA polymerase elements, including the F loop and the jaw domain, as well as external regulatory factors on the trigger loop folding and catalysis.

  13. Capillary pumped loop body heat exchanger

    Science.gov (United States)

    Swanson, Theodore D. (Inventor); Wren, deceased, Paul (Inventor)

    1998-01-01

    A capillary pumped loop for transferring heat from one body part to another body part, the capillary pumped loop comprising a capillary evaporator for vaporizing a liquid refrigerant by absorbing heat from a warm body part, a condenser for turning a vaporized refrigerant into a liquid by transferring heat from the vaporized liquid to a cool body part, a first tube section connecting an output port of the capillary evaporator to an input of the condenser, and a second tube section connecting an output of the condenser to an input port of the capillary evaporator. A wick may be provided within the condenser. A pump may be provided between the second tube section and the input port of the capillary evaporator. Additionally, an esternal heat source or heat sink may be utilized.

  14. A new vacuum for Loop Quantum Gravity

    CERN Document Server

    Dittrich, Bianca

    2014-01-01

    We construct a new vacuum for loop quantum gravity, which is dual to the Ashtekar-Lewandowski vacuum. Because it is based on BF theory, this new vacuum is physical for $(2+1)$-dimensional gravity, and much closer to the spirit of spin foam quantization in general. To construct this new vacuum and the associated representation of quantum observables, we introduce a modified holonomy-flux algebra which is cylindrically consistent with respect to the notion of refinement by time evolution suggested in [1]. This supports the proposal for a construction of a physical vacuum made in [1,2], also for $(3+1)$-dimensional gravity. We expect that the vacuum introduced here will facilitate the extraction of large scale physics and cosmological predictions from loop quantum gravity.

  15. Loop transfer recovery for general observer architecture

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Søgaard-Andersen, Per; Stoustrup, Jakob

    1991-01-01

    A general and concise formulation is given of the loop transfer recovery (LTR) design problem based on recovery errors. Three types of recovery errors are treated: open loop recovery, sensitivity recovery and input-output recovery errors. The three corresponding versions of the asymptotic recovery...... recovery cases. This general recovery formulation covers all known observer based compensator types as special cases. The conditions given in this setting are effectively the aim of all known LTR design methods. The recovery formulation is interpreted in terms of a modelmatching problem as well, which...... is examined by means of the Q-parametrization. It is shown how the general controller obtained by the Q-parametrization can be written as a Luenberger observer based controller. In all cases, n controller states suffice to achieve recovery. The compensators are characterized for errors both on the input...

  16. Loop quantization of the Schwarzschild black hole.

    Science.gov (United States)

    Gambini, Rodolfo; Pullin, Jorge

    2013-05-24

    We quantize spherically symmetric vacuum gravity without gauge fixing the diffeomorphism constraint. Through a rescaling, we make the algebra of Hamiltonian constraints Abelian, and therefore the constraint algebra is a true Lie algebra. This allows the completion of the Dirac quantization procedure using loop quantum gravity techniques. We can construct explicitly the exact solutions of the physical Hilbert space annihilated by all constraints. New observables living in the bulk appear at the quantum level (analogous to spin in quantum mechanics) that are not present at the classical level and are associated with the discrete nature of the spin network states of loop quantum gravity. The resulting quantum space-times resolve the singularity present in the classical theory inside black holes.

  17. MBNL expression in autoregulatory feedback loops.

    Science.gov (United States)

    Konieczny, Patryk; Stepniak-Konieczna, Ewa; Sobczak, Krzysztof

    2017-09-26

    Muscleblind-like (MBNL) proteins bind to hundreds of pre- and mature mRNAs to regulate their alternative splicing, alternative polyadenylation, stability and subcellular localization. Once MBNLs are withheld from transcript regulation, cellular machineries generate products inapt for precise embryonal/adult developmental tasks and myotonic dystrophy, a devastating multi-systemic genetic disorder, develops. We have recently demonstrated that all three MBNL paralogs are capable of fine-tuning cellular content of one of the three MBNL paralogs, MBNL1, by binding to the first coding exon (e1) of its pre-mRNA. Intriguingly, this autoregulatory feedback loop grounded on alternative splicing of e1 appears to play a crucial role in delaying the onset of myotonic dystrophy. Here, we describe this process in the context of other autoregulatory and regulatory loops that maintain the content and diverse functions of MBNL proteins at optimal level in health and disease, thus supporting the overall cellular homeostasis.

  18. Dynamical Casimir effect and loop corrections

    Science.gov (United States)

    Akhmedov, E. T.; Alexeev, S. O.

    2017-09-01

    We calculate quantum loop corrections to the stress-energy flux caused by moving mirrors. We consider massless, self-interacting, ϕ4, real scalar theory. In these calculations we encounter new and quite unexpected subtleties due to the absence of global hyperbolicity in the presence of mirrors. We attempt to clearly phrase as many hidden assumptions and complications as possible that appear while solving the problem in question. On top of that, we find that quantum loop corrections to the stress-energy flux grow with time and are not suppressed in comparison with the semiclassical contributions. Thus, we observe the breakdown of the perturbation theory, and we discuss its physical origin and ways to deal with such a situation. As a byproduct, we observe a similarity of the problem in question with that for the minimally coupled, massless scalar field in de Sitter space.

  19. The gluon beam function at two loops

    Science.gov (United States)

    Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J.

    2014-08-01

    The virtuality-dependent beam function is a universal ingredient in the resummation for observables probing the virtuality of incoming partons, including N -jettiness and beam thrust. We compute the gluon beam function at two-loop order. Together with our previous results for the two-loop quark beam function, this completes the full set of virtuality-dependent beam functions at next-to-next-to-leading order (NNLO). Our results are required to account for all collinear initial-state radiation effects on the N -jettiness event shape through N3LL order. We present numerical results for both the quark and gluon beam functions up to NNLO and N3LL order. Numerically, the NNLO matching corrections are important. They reduce the residual matching scale dependence in the resummed beam function by about a factor of two.

  20. The gluon beam function at two loops

    Energy Technology Data Exchange (ETDEWEB)

    Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group

    2014-05-15

    The virtuality-dependent beam function is a universal ingredient in the resummation for observables probing the virtuality of incoming partons, including N-jettiness and beam thrust. We compute the gluon beam function at two-loop order. Together with our previous results for the two-loop quark beam function, this completes the full set of virtuality-dependent beam functions at next-to-next-to-leading order (NNLO). Our results are required to account for all collinear ISR effects to the N-jettiness event shape through N{sup 3}LL order. We present numerical results for both the quark and gluon beam functions up to NNLO and N{sup 3}LL order. Numerically, the NNLO matching corrections are important. They reduce the residual matching scale dependence in the resummed beam function by about a factor of two.

  1. Water from (waste)water--the dependable water resource.

    Science.gov (United States)

    Asano, Takashi

    2002-01-01

    Water reclamation and reuse provides a unique and viable opportunity to augment traditional water supplies. As a multi-disciplined and important element of water resources development and management, water reuse can help to close the loop between water supply and wastewater disposal. Effective water reuse requires integration of water and reclaimed water supply functions. The successful development of this dependable water resource depends upon close examination and synthesis of elements from infrastructure and facilities planning, wastewater treatment plant siting, treatment process reliability, economic and financial analyses, and water utility management. In this paper, fundamental concepts of water reuse are discussed including definitions, historical developments, the role of water recycling in the hydrologic cycle, categories of water reuse, water quality criteria and regulatory requirements, and technological innovations for the safe use of reclaimed water. The paper emphasizes the integration of this alternative water supply into water resources planning, and the emergence of modern water reclamation and reuse practices from wastewater to reclaimed water to repurified water.

  2. Impact of the amount of working fluid in loop heat pipe to remove waste heat from electronic component

    Directory of Open Access Journals (Sweden)

    Smitka Martin

    2014-03-01

    Full Text Available One of the options on how to remove waste heat from electronic components is using loop heat pipe. The loop heat pipe (LHP is a two-phase device with high effective thermal conductivity that utilizes change phase to transport heat. It was invented in Russia in the early 1980’s. The main parts of LHP are an evaporator, a condenser, a compensation chamber and a vapor and liquid lines. Only the evaporator and part of the compensation chamber are equipped with a wick structure. Inside loop heat pipe is working fluid. As a working fluid can be used distilled water, acetone, ammonia, methanol etc. Amount of filling is important for the operation and performance of LHP. This work deals with the design of loop heat pipe and impact of filling ratio of working fluid to remove waste heat from insulated gate bipolar transistor (IGBT.

  3. Harmonic Oscillator SUSY Partners and Evolution Loops

    Directory of Open Access Journals (Sweden)

    David J. Fernández

    2012-07-01

    Full Text Available Supersymmetric quantum mechanics is a powerful tool for generating exactly solvable potentials departing from a given initial one. If applied to the harmonic oscillator, a family of Hamiltonians ruled by polynomial Heisenberg algebras is obtained. In this paper it will be shown that the SUSY partner Hamiltonians of the harmonic oscillator can produce evolution loops. The corresponding geometric phases will be as well studied.

  4. Two-loop statsum of superstrings

    Science.gov (United States)

    Morozov, A.

    1988-06-01

    We discuss, whether there is a choice of odd moduli on super-Riemann surfaces of genus p≳2, which leads to the vanishing of statistical sums of superstrings before integration over the space of even moduli. The answer is shown to be positive at least for p=2, when odd moduli are localized at ramification points. The relation between various definitions of many-loop statistical sums in superstring theory is discussed.

  5. High Temperature Fluoride Salt Test Loop

    Energy Technology Data Exchange (ETDEWEB)

    Aaron, Adam M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cunningham, Richard Burns [Univ. of Tennessee, Knoxville, TN (United States); Fugate, David L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holcomb, David Eugene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kisner, Roger A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Peretz, Fred J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wilson, Dane F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yoder, Jr, Graydon L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-12-01

    Effective high-temperature thermal energy exchange and delivery at temperatures over 600°C has the potential of significant impact by reducing both the capital and operating cost of energy conversion and transport systems. It is one of the key technologies necessary for efficient hydrogen production and could potentially enhance efficiencies of high-temperature solar systems. Today, there are no standard commercially available high-performance heat transfer fluids above 600°C. High pressures associated with water and gaseous coolants (such as helium) at elevated temperatures impose limiting design conditions for the materials in most energy systems. Liquid salts offer high-temperature capabilities at low vapor pressures, good heat transport properties, and reasonable costs and are therefore leading candidate fluids for next-generation energy production. Liquid-fluoride-salt-cooled, graphite-moderated reactors, referred to as Fluoride Salt Reactors (FHRs), are specifically designed to exploit the excellent heat transfer properties of liquid fluoride salts while maximizing their thermal efficiency and minimizing cost. The FHR s outstanding heat transfer properties, combined with its fully passive safety, make this reactor the most technologically desirable nuclear power reactor class for next-generation energy production. Multiple FHR designs are presently being considered. These range from the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) [1] design originally developed by UC-Berkeley to the Small Advanced High-Temperature Reactor (SmAHTR) and the large scale FHR both being developed at ORNL [2]. The value of high-temperature, molten-salt-cooled reactors is also recognized internationally, and Czechoslovakia, France, India, and China all have salt-cooled reactor development under way. The liquid salt experiment presently being developed uses the PB-AHTR as its focus. One core design of the PB-AHTR features multiple 20 cm diameter, 3.2 m long fuel channels

  6. Transverse loop colostomy and colonic motility.

    Science.gov (United States)

    Pucciani, F; Ringressi, M N; Maltinti, G; Bechi, P

    2014-11-01

    The motility of the defunctionalized colon, distal to transverse loop colostomy, has never been studied "in vivo." The aim of our study was to evaluate the influence of transverse loop colostomy on colonic motility. Thirteen patients were examined before stoma closure by means of clinical evaluation and colonic manometry; we studied both the right and distal colon in both fasting and fed patients in order to detect motor activity. Quantitative and qualitative manometric analyses showed that the diverted colon had motor activity even if no regular colonic motor pattern was observed. The spreading of aboral propagated contractions (PCs) was sometimes recorded from the right colon to the distal colon. The response of the proximal and distal colon to a standard meal, when compared to fasting values, increased more than 40 and 35 %, respectively. Stool and gas ejections from the colostomy were never related to a particular type of colonic motility: Motor quiescence such as PCs was chaotically related to stool escape. In conclusion, motility of the defunctionalized colon is preserved in patients with transverse loop colostomy.

  7. Leptogenesis from loop effects in curved spacetime

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Jamie I.; Shore, Graham M. [Department of Physics, Swansea University,Singleton Park, Swansea, SA2 8PP (United Kingdom)

    2016-04-05

    We describe a new mechanism — radiatively-induced gravitational leptogenesis — for generating the matter-antimatter asymmetry of the Universe. We show how quantum loop effects in C and CP violating theories cause matter and antimatter to propagate differently in the presence of gravity, and prove this is forbidden in flat space by CPT and translation symmetry. This generates a curvature-dependent chemical potential for leptons, allowing a matter-antimatter asymmetry to be generated in thermal equilibrium in the early Universe. The time-dependent dynamics necessary for leptogenesis is provided by the interaction of the virtual self-energy cloud of the leptons with the expanding curved spacetime background, which violates the strong equivalence principle and allows a distinction between matter and antimatter. We show here how this mechanism is realised in a particular BSM theory, the see-saw model, where the quantum loops involve the heavy sterile neutrinos responsible for light neutrino masses. We demonstrate by explicit computation of the relevant two-loop Feynman diagrams how the size of the radiative corrections relevant for leptogenesis becomes enhanced by increasing the mass hierarchy of the sterile neutrinos, and show how the induced lepton asymmetry may be sufficiently large to play an important rôle in determining the baryon-to-photon ratio of the Universe.

  8. Quantum Loop Topography for Machine Learning

    Science.gov (United States)

    Zhang, Yi; Kim, Eun-Ah

    2017-05-01

    Despite rapidly growing interest in harnessing machine learning in the study of quantum many-body systems, training neural networks to identify quantum phases is a nontrivial challenge. The key challenge is in efficiently extracting essential information from the many-body Hamiltonian or wave function and turning the information into an image that can be fed into a neural network. When targeting topological phases, this task becomes particularly challenging as topological phases are defined in terms of nonlocal properties. Here, we introduce quantum loop topography (QLT): a procedure of constructing a multidimensional image from the "sample" Hamiltonian or wave function by evaluating two-point operators that form loops at independent Monte Carlo steps. The loop configuration is guided by the characteristic response for defining the phase, which is Hall conductivity for the cases at hand. Feeding QLT to a fully connected neural network with a single hidden layer, we demonstrate that the architecture can be effectively trained to distinguish the Chern insulator and the fractional Chern insulator from trivial insulators with high fidelity. In addition to establishing the first case of obtaining a phase diagram with a topological quantum phase transition with machine learning, the perspective of bridging traditional condensed matter theory with machine learning will be broadly valuable.

  9. Leptogenesis from loop effects in curved spacetime

    Science.gov (United States)

    McDonald, Jamie I.; Shore, Graham M.

    2016-04-01

    We describe a new mechanism — radiatively-induced gravitational leptogenesis — for generating the matter-antimatter asymmetry of the Universe. We show how quantum loop effects in C and CP violating theories cause matter and antimatter to propagate differently in the presence of gravity, and prove this is forbidden in flat space by CPT and translation symmetry. This generates a curvature-dependent chemical potential for leptons, allowing a matter-antimatter asymmetry to be generated in thermal equilibrium in the early Universe. The time-dependent dynamics necessary for leptogenesis is provided by the interaction of the virtual self-energy cloud of the leptons with the expanding curved spacetime background, which violates the strong equivalence principle and allows a distinction between matter and antimatter. We show here how this mechanism is realised in a particular BSM theory, the see-saw model, where the quantum loops involve the heavy sterile neutrinos responsible for light neutrino masses. We demonstrate by explicit computation of the relevant two-loop Feynman diagrams how the size of the radiative corrections relevant for leptogenesis becomes enhanced by increasing the mass hierarchy of the sterile neutrinos, and show how the induced lepton asymmetry may be sufficiently large to play an important rôle in determining the baryon-to-photon ratio of the Universe.

  10. The quark beam function at two loops

    Science.gov (United States)

    Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J.

    2014-04-01

    In differential measurements at a hadron collider, collinear initial-state radiation is described by process-independent beam functions. They are the field-theoretic analog of initial-state parton showers. Depending on the measured observable they are differential in the virtuality and/or transverse momentum of the colliding partons in addition to the usual longitudinal momentum fraction. Perturbatively, the beam functions can be calculated by matching them onto standard quark and gluon parton distribution functions. We calculate the inclusive virtuality-dependent quark beam function at NNLO, which is relevant for any observables probing the virtuality of the incoming partons, including N -jettiness and beam thrust. For such observables, our results are an important ingredient in the resummation of large logarithms at N3LL order, and provide all contributions enhanced by collinear t-channel singularities at NNLO for quark-initiated processes in analytic form. We perform the calculation in both Feynman and axial gauge and use two different methods to evaluate the discontinuity of the two-loop Feynman diagrams, providing nontrivial checks of the calculation. As part of our results we reproduce the known two-loop QCD splitting functions and confirm at two loops that the virtuality-dependent beam and final-state jet functions have the same anomalous dimension.

  11. The quark beam function at two loops

    Energy Technology Data Exchange (ETDEWEB)

    Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J.

    2014-01-15

    In differential measurements at a hadron collider, collinear initial-state radiation is described by process-independent beam functions. They are the field-theoretic analog of initial-state parton showers. Depending on the measured observable they are differential in the virtuality and/or transverse momentum of the colliding partons in addition to their usual longitudinal momentum fractions. Perturbatively, the beam functions can be calculated by matching them onto standard quark and gluon parton distribution functions. We calculate the inclusive virtuality-dependent quark beam function at NNLO, which is relevant for any observables probing the virtuality of the incoming partons, including N-jettiness and beam thrust. For such observables, our results are an important ingredient in the resummation of large logarithms at N{sup 3}LL order, and provide all contributions enhanced by collinear t-channel singularities at NNLO for quark-initiated processes in analytic form. We perform the calculation in both Feynman and axial gauge and use two different methods to evaluate the discontinuity in the two-loop Feynman diagrams, providing nontrivial checks of the calculation. As part of our results we reproduce the known two-loop QCD splitting functions and confirm at two loops that the virtuality-dependent beam and final-state jet functions have the same anomalous dimension.

  12. The quark beam function at two loops

    Energy Technology Data Exchange (ETDEWEB)

    Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J. [Theory Group, Deutsches Elektronen-Synchrotron (DESY),D-22607 Hamburg (Germany)

    2014-04-16

    In differential measurements at a hadron collider, collinear initial-state radiation is described by process-independent beam functions. They are the field-theoretic analog of initial-state parton showers. Depending on the measured observable they are differential in the virtuality and/or transverse momentum of the colliding partons in addition to the usual longitudinal momentum fraction. Perturbatively, the beam functions can be calculated by matching them onto standard quark and gluon parton distribution functions. We calculate the inclusive virtuality-dependent quark beam function at NNLO, which is relevant for any observables probing the virtuality of the incoming partons, including N-jettiness and beam thrust. For such observables, our results are an important ingredient in the resummation of large logarithms at N{sup 3}LL order, and provide all contributions enhanced by collinear t-channel singularities at NNLO for quark-initiated processes in analytic form. We perform the calculation in both Feynman and axial gauge and use two different methods to evaluate the discontinuity of the two-loop Feynman diagrams, providing nontrivial checks of the calculation. As part of our results we reproduce the known two-loop QCD splitting functions and confirm at two loops that the virtuality-dependent beam and final-state jet functions have the same anomalous dimension.

  13. Key issues in the computational simulation of GPCR function: representation of loop domains

    Science.gov (United States)

    Mehler, E. L.; Periole, X.; Hassan, S. A.; Weinstein, H.

    2002-11-01

    Some key concerns raised by molecular modeling and computational simulation of functional mechanisms for membrane proteins are discussed and illustrated for members of the family of G protein coupled receptors (GPCRs). Of particular importance are issues related to the modeling and computational treatment of loop regions. These are demonstrated here with results from different levels of computational simulations applied to the structures of rhodopsin and a model of the 5-HT2A serotonin receptor, 5-HT2AR. First, comparative Molecular Dynamics (MD) simulations are reported for rhodopsin in vacuum and embedded in an explicit representation of the membrane and water environment. It is shown that in spite of a partial accounting of solvent screening effects by neutralization of charged side chains, vacuum MD simulations can lead to severe distortions of the loop structures. The primary source of the distortion appears to be formation of artifactual H-bonds, as has been repeatedly observed in vacuum simulations. To address such shortcomings, a recently proposed approach that has been developed for calculating the structure of segments that connect elements of secondary structure with known coordinates, is applied to 5-HT2AR to obtain an initial representation of the loops connecting the transmembrane (TM) helices. The approach consists of a simulated annealing combined with biased scaled collective variables Monte Carlo technique, and is applied to loops connecting the TM segments on both the extra-cellular and the cytoplasmic sides of the receptor. Although this initial calculation treats the loops as independent structural entities, the final structure exhibits a number of interloop interactions that may have functional significance. Finally, it is shown here that in the case where a given loop from two different GPCRs (here rhodopsin and 5-HT2AR) has approximately the same length and some degree of sequence identity, the fold adopted by the loops can be similar. Thus

  14. System for vibroacoustic inspection of equipment in the first loop of an atomic electric power plant. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    Samarin, A.A.; Krasyuk, V.Ya.; Ivanov, Yu.S.; Pospelko, A.A.

    1975-11-01

    A system is described for vibroacoustic inspection of equipment in the first loop of a nuclear power plant with water-moderated water-cooled power reactors. This monitoring system is now in operation at the Novovoronezh Power Plant. The installation performs the following functions: measurement and registration of effective and peak levels of structural noise and vibrations of the main technological equipment in the first loop; amplitude-frequency analysis of structural noises and vibration of equipment; (sound and light) signaling when the current noise level and vibration level exceed the present level; provides facilities for an operator to listen to structural noise of running equipment.

  15. Gravitational smoothing of kinks on cosmic string loops

    CERN Document Server

    Wachter, Jeremy M

    2016-01-01

    We analyze the effect of gravitational back reaction on cosmic string loops with kinks, which is an important determinant of the shape, and thus the potential observability, of string loops which may exist in the universe today. Kinks are not rounded off, but may be straightened out. In some loops, symmetries prevent even this process, so that the loop evaporates in a self-similar fashion and the kinks are unchanged. As an example, we give results for the rectangular Garfinkle-Vachaspati loop.

  16. On Vanishing Two Loop Cosmological Constants in Nonsupersymmetric Strings

    Energy Technology Data Exchange (ETDEWEB)

    Kachru, S

    1998-10-22

    It has recently been suggested that in certain special nonsupersymmetric type II string compactifications, at least the first two perturbative contributions to the cosmological constant Lambda vanish. Support for perturbative vanishing beyond 1-loop (as well as evidence for the absence of some nonperturbative contributions) has come from duality arguments. There was also a direct 2-loop computation which was incomplete; in this note we explain the deficiency of the previous 2-loop calculation and discuss the complete 2-loop computation in two different models. The corrected analysis yields a vanishing 2-loop contribution to Lambda in these models.

  17. Simulaciones numéricas en modelos de loops

    OpenAIRE

    Serna Martínez, Pablo

    2014-01-01

    El objetivo de esta tesis consiste en el estudio de varias familias de modelos de loops en dos y tres dimensiones, donde se encuentran dos fases diferentes: una con loops finitos y otra donde hay al menos uno infinito. En concreto, se han estudiado tres clases de modelos de loops. El primero, un modelo de loops tridimensionales con orientación y color, definidos en redes con número de coordinación cuatro. El segundo, una modificación de estos modelos de loops que es un firme candidato ...

  18. On the loop-loop scattering amplitudes in Abelian and non-Abelian gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Meggiolaro, Enrico [Dipartimento di Fisica, Universita di Pisa, Largo Pontecorvo 3, I-56127 Pisa (Italy)]. E-mail: enrico.meggiolaro@df.unipi.it

    2005-02-14

    The high-energy elastic scattering amplitude of two colour-singlet qq-bar pairs is governed by the correlation function of two Wilson loops, which follow the classical straight lines for quark (antiquark) trajectories. This quantity is expected to be free of IR divergences, differently from what happens for the parton-parton elastic scattering amplitude, described, in the high-energy limit, by the expectation value of two Wilson lines. We shall explicitly test this IR finiteness by a direct non-perturbative computation of the loop-loop scattering amplitudes in the (pedagogic, but surely physically interesting) case of quenched QED. The results obtained for the Abelian case will be generalized to the case of a non-Abelian gauge theory with Nc colours, but stopping to the order O(g4) in perturbation theory. In connection with the above-mentioned IR finiteness, we shall also discuss some analytic properties of the loop-loop scattering amplitudes in both Abelian and non-Abelian gauge theories, when going from Minkowskian to Euclidean theory, which can be relevant to the still unsolved problem of the s-dependence of hadron-hadron total cross-sections.

  19. SDG and E - ERDA Geothermal Loop Experimental Facility. Bi-monthly report, May 1975-August 1976

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, H.K.; Bricarello, J.R.; Campbell, J.A.; Lombard, G.L.; Mulliner, D.K.; Swanson, C.R.

    1976-09-01

    A description of the Geothermal Loop Experimental Facility (GLEF) its construction problems, and a discussion of start-up testing are included. A history and description of the operation and maintenance with the brine injection pump for the facility are presented. The GLEF was divided into five separate sections: steam and condensate system, brine system, purge water system, vent gas system, and cooling water system. An insight into the chemistry of each system is provided by analysis of samples taken. Scaling and corrosion effects of brine, steam, gas, and water in these systems are described in detail. (MHR)

  20. Gauge and Gravity Amplitudes from Trees to Loops

    DEFF Research Database (Denmark)

    Huang, Rijun

    This thesis describes two subjects that I mainly work on during my PhD study. They are both about scattering amplitudes, covering gravity and gauge theories, tree and loop level, with or without supersymmetry. The rst subject is Kawai-Lewellen-Tye(KLT) relation in field theory, which mysteriously...... a special type of two-loop and three-loop diagrams where equations of maximal unitarity cut de ne complex curve. Geometry genus of complex curve is a topological invariant, and characterizes the property of curve. We compute the genus of complex curve for some two-loop and three-loop diagrams from...... for vanishing identities of Yang-Mills amplitudes as violation of linear symmetry groups based on KLT relation argument. The second subject is integrand reduction of multi-loop amplitude. The recent methods based on computational algebraic geometry make it possible to systematically study multi-loop amplitude...

  1. Optimatization of loop heat pipe for cooling of electrotechnical box

    Science.gov (United States)

    Roman, Banovcan; Tomas, Puchor; Andrej, Kapjor; Milan, Malcho

    2017-09-01

    The paper deals with use of LOOP thermosyphon heat pipe to transfer heat from electrotechnical box and describe of construction individual types of LOOP heat pipes. The LOOP heat pipe is very good cooling device which requires no mechanical parts in their design. LOOP heat pipe use only phase change during heat transfer, without a compressor, fan or pump. LOOP heat pipe is more energy saving compared to conventional cooling systems with forced convection. The main advantage of cooling by heat pipe is that electrotechnical box can be hermetically closed (dust -free construction), because dust reduces the lifetime of electrotechnical elements in box. Lifetime of LOOP heat pipe equals to the lifetime of construction material. The paper describes mathematical model of LOOP thermosyphon heat pipe (condenser). Compares selected types of working fluids which are filled with a heat pipe and construction materials of heat pipe.

  2. Analytical on shell QED results 3-loop vacuum polarization, 4-loop $\\beta$-function and the muon anomaly

    CERN Document Server

    Broadhurst, D J; Tarasov, O V

    1993-01-01

    We present the results of analytical calculations of the 3-loop contributions to the asymptotic photon vacuum polarization function, in the on shell scheme, and of the 4-loop contributions to the on shell QED beta-function. These are used to evaluate various 4-loop and 5-loop contributions to the muon anomaly. Our analytical contributions to (g-2)_\\mu differ significantly from previous numerical results. A very recent numerical re-evaluation of 4-loop muon-anomaly contributions has yielded results much closer to ours.

  3. 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

  4. Pemakaian Crown Loop dan Band Loop di Rahang Bawah Anak Usia Enam Tahun (Laporan Kasus

    Directory of Open Access Journals (Sweden)

    Rivi Isabela

    2015-11-01

    Full Text Available The function of space maintainer is to preserve arch length following the premature loss of a primary teeth. Early loss of primary tooth may compromise the eruption of succedaneous teeth if there is a reduction in the arch length. The Band and Crown Loop are used to maintain the loss of primary molar. The report describe a 6 year old girl who has premature loss of second left mandibular primary molar and first right mandibular primary molar treated using crown and band loop space maintainer. The patient still has mastication function from other posterior primary teeth.

  5. The 1/2 BPS Wilson loop in ABJM theory at two loops

    OpenAIRE

    Bianchi, Marco S.; Giribet, Gaston Enrique; Leoni Olivera, Matías; Penati, Silvia

    2013-01-01

    We compute the expectation value of the 1/2 BPS circular Wilson loop in ABJM theory at two loops in perturbation theory. The result shows perfect agreement with the prediction from localization and the proposed framing factor. Fil: Bianchi, Marco S.. Institut für Physik. Humboldt-Universität zu Berlin; Alemania; Fil: Giribet, Gaston Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Bue...

  6. LISA Pathfinder closed-loop analysis: a model breakdown of the in-loop observables

    Science.gov (United States)

    LISA Pathfinder Collaboration

    2017-05-01

    This paper describes a methodology to analyze, in the frequency domain, the steady-state control performances of the LISA Pathfinder mission. In particular, it provides a technical framework to give a comprehensive understanding of the spectra of all the degrees of freedom by breaking them down into their various physical origins, hence bringing out the major contributions of the control residuals. A reconstruction of the measured in-loop output, extracted from a model of the closed-loop system, is shown as an instance to illustrate the potential of such a model breakdown of the data.

  7. Open-loop and closed-loop control of flying qubits

    Energy Technology Data Exchange (ETDEWEB)

    Lucamarini, M; Di Giuseppe, G; Vitali, D; Tombesi, P, E-mail: marco.lucamarini@unicam.it [School of Science and Technology, Physics Division, University of Camerino, I-62032 Camerino (Italy)

    2011-08-14

    We describe two recent techniques, along with related experiments, to control and reduce the noise affecting a photon polarization qubit. The first is based on the open-loop 'bang-bang' method, where suitably tailored pulses are implemented on the system to prevent polarization decoherence. This requires only passive elements when the physical system is a photon and the operation is performed in space rather than in time. The second technique is based on closed-loop 'asymmetric feedback', where some quantities are measured and used for a real-time correction of the system dynamics. This technique necessarily requires active electronics to work.

  8. Loop securities of arthroscopic sliding-knot techniques when the suture loop is not evenly tensioned.

    Science.gov (United States)

    Kim, Sae Hoon; Glaser, Diana; Doan, Josh; Chung, Seok Won; Choi, Hye Yeon; Oh, Joo Han; Hargens, Alan R

    2013-08-01

    The purpose of this study was to evaluate the loop security of arthroscopic sliding knots when tension is only applied to the post strand and not the loop strand. Six different locking sliding knots (Weston, Nicky, Roeder, SMC, San Diego, and Dines) were included. Loop securities were evaluated in 2 ways: with a conventional method (equal tension applied to the suture loop) and with a worst-case scenario (WCS) method (only the post strand of the suture loop was tensioned). Differences between test methods were evaluated for significance. To help assess the applicability of each test method, loop-security testing in a cadaveric shoulder was performed with 1 type of knot (SMC). Loop securities with the conventional method versus the WCS method were as follows: 10.74 ± 4.20 N versus 6.90 ± 3.90 N for Weston, 21.25 ± 14.74 N versus 8.73 ± 3.35 N for Nicky, 26.14 ± 15.57 N versus 7.95 ± 4.23 N for Roeder, 42.67 ± 22.96 N versus 8.67 ± 4.33 N for SMC, 52.99 ± 21.36 N versus 18.25 ± 10.58 N for San Diego, and 89.27 ± 27.96 N versus 12.48 ± 3.40 N for Dines (P security of 5.53 ± 6.06 N, which was similar to the WCS setting. The locking mechanism of the sliding knots is maintained when the suture loop is evenly tensioned at both post and non-post strands. When tension is not applied to the non-post strand side, the knots slide more easily and fail at lower loads than previously reported. When surgeons tie locking sliding knots in single-row rotator cuff repair, they should be aware that the knots could fail at much lower loads than previously reported. Copyright © 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  9. A Refractive Index Sensor Based on the Resonant Coupling to Cladding Modes in a Fiber Loop

    Science.gov (United States)

    Reyes, Mauricio; Monzón-Hernández, David; Martínez-Ríos, Alejandro; Silvestre, Enrique; Díez, Antonio; Cruz, José Luis; Andrés, Miguel V.

    2013-01-01

    We report an easy-to-build, compact, and low-cost optical fiber refractive index sensor. It consists of a single fiber loop whose transmission spectra exhibit a series of notches produced by the resonant coupling between the fundamental mode and the cladding modes in a uniformly bent fiber. The wavelength of the notches, distributed in a wavelength span from 1,400 to 1,700 nm, can be tuned by adjusting the diameter of the fiber loop and are sensitive to refractive index changes of the external medium. Sensitivities of 170 and 800 nm per refractive index unit for water solutions and for the refractive index interval 1.40–1.442, respectively, are demonstrated. We estimate a long range resolution of 3 × 10−4 and a short range resolution of 2 × 10−5 for water solutions. PMID:23979478

  10. Closing the loop of deep brain stimulation

    Directory of Open Access Journals (Sweden)

    Romain eCARRON

    2013-12-01

    Full Text Available High-frequency deep brain stimulation is used to treat a wide range of brain disorders, like Parkinson's disease. The stimulated networks usually share common electrophysiological signatures, including hyperactivity and/or dysrhythmia. From a clinical perspective, HFS is expected to alleviate clinical signs without generating adverse effects. Here, we consider whether the classical open-loop HFS fulfils these criteria and outline current experimental or theoretical research on the different types of closed-loop DBS that could provide better clinical outcomes. In the first part of the review, the two routes followed by HFS-evoked axonal spikes are explored. In one direction, orthodromic spikes functionally de-afferent the stimulated nucleus from its downstream target networks. In the opposite direction, antidromic spikes prevent this nucleus from being influenced by its afferent networks. As a result, the pathological synchronized activity no longer propagates from the cortical networks to the stimulated nucleus. The overall result can be described as a reversible functional de-afferentation of the stimulated nucleus from its upstream and downstream nuclei. In the second part of the review, the latest advances in closed-loop DBS are considered. Some of the proposed approaches are based on mathematical models, which emphasize different aspects of the parkinsonian basal ganglia: excessive synchronization, abnormal firing-rate rhythms, and a deficient thalamo-cortical relay. The stimulation strategies are classified depending on the control-theory techniques on which they are based: adaptive and on-demand stimulation schemes, delayed and multi-site approaches, stimulations based on proportional and/or derivative control actions, optimal control strategies. Some of these strategies have been validated experimentally, but there is still a large reservoir of theoretical work that may point to ways of improving practical treatment.

  11. Observational constraints on loop quantum cosmology.

    Science.gov (United States)

    Bojowald, Martin; Calcagni, Gianluca; Tsujikawa, Shinji

    2011-11-18

    In the inflationary scenario of loop quantum cosmology in the presence of inverse-volume corrections, we give analytic formulas for the power spectra of scalar and tensor perturbations convenient to compare with observations. Since inverse-volume corrections can provide strong contributions to the running spectral indices, inclusion of terms higher than the second-order runnings in the power spectra is crucially important. Using the recent data of cosmic microwave background and other cosmological experiments, we place bounds on the quantum corrections.

  12. Loops in Reeb Graphs of 2-Manifolds

    Energy Technology Data Exchange (ETDEWEB)

    Cole-McLaughlin, K; Edelsbrunner, H; Harer, J; Natarajan, V; Pascucci, V

    2004-12-16

    Given a Morse function f over a 2-manifold with or without boundary, the Reeb graph is obtained by contracting the connected components of the level sets to points. We prove tight upper and lower bounds on the number of loops in the Reeb graph that depend on the genus, the number of boundary components, and whether or not the 2-manifold is orientable. We also give an algorithm that constructs the Reeb graph in time O(n log n), where n is the number of edges in the triangulation used to represent the 2-manifold and the Morse function.

  13. Frequency acquisition techniques for phase locked loop

    CERN Document Server

    Talbot, Daniel

    2012-01-01

    Many good phaselocked loops (PLL) books exist. However, how to acquire the input frequency from an unlocked state is rarely covered. This book explores the methods for achieving this locked state for a variety of conditions. Using a minimum of mathematics, it introduces engineers to performance limitations of phase/frequency detector based PLL, the quadricorrelator method for both continuous and sampled mode, sawtooth ramp-and-sample phase detector, self-sweeping self-extinguishing topology, and sweep methods using quadrature mixer based lock detection. Digital implementations versus analog are also considered.

  14. Chemical Looping Combustion of Rice Husk

    OpenAIRE

    Rashmeet Singh Monga; Ganesh R. Kale

    2015-01-01

    A thermodynamic investigation of direct chemical looping combustion (CLC) of rice husk is presented in this paper. Both steam and CO2 are used for gasification within the temperature range of 500–1200˚C and different amounts of oxygen carriers. Chemical equilibrium model was considered for the CLC fuel reactor. The trends in product compositions of the fuel reactor, were determined. Rice husk gasification using 3 moles H2O and 0 moles CO2 per mole carbon (in rice husk) at 1 bar pr...

  15. Towards a four-loop form factor

    OpenAIRE

    Boels, Rutger; Kniehl, Bernd A.; YANG, GANG

    2016-01-01

    The four-loop, two-point form factor contains the first non-planar correction to the lightlike cusp anomalous dimension. This anomalous dimension is a universal function which appears in many applications. Its planar part in N = 4 SYM is known, in principle, exactly from AdS/CFT and integrability while its non-planar part has been conjectured to vanish. The integrand of the form factor of the stress-tensor multiplet in N = 4 SYM including the non-planar part was obtained in previous work. We ...

  16. Thermoelectric power generator with intermediate loop

    Science.gov (United States)

    Bell, Lon E; Crane, Douglas Todd

    2013-05-21

    A thermoelectric power generator is disclosed for use to generate electrical power from heat, typically waste heat. An intermediate heat transfer loop forms a part of the system to permit added control and adjustability in the system. This allows the thermoelectric power generator to more effectively and efficiently generate power in the face of dynamically varying temperatures and heat flux conditions, such as where the heat source is the exhaust of an automobile, or any other heat source with dynamic temperature and heat flux conditions.

  17. Advanced Hardware Protection of Metallic Loops

    Directory of Open Access Journals (Sweden)

    Mach Václav

    2017-01-01

    Full Text Available This article deals with the advanced protection of metallic loops using addition electronic components. The main goal of this article is to improve especially Advanced Technology Zone (ATZ, which is the most applied method. The improvement consists of protection against overvoltage which can destroy the Control and Indicating Equipment (CIE and it consist of adding more states which have the impact of numbers of connected detectors. All ideas are introduced with technical details, schematic and every idea also comes with an explanation.

  18. Gauge and Integrable Theories in Loop Spaces

    OpenAIRE

    Ferreira, L. A.; Luchini, G.

    2011-01-01

    We propose an integral formulation of the equations of motion of a large class of field theories which leads in a quite natural and direct way to the construction of conservation laws. The approach is based on generalized non-abelian Stokes theorems for p-form connections, and its appropriate mathematical language is that of loop spaces. The equations of motion are written as the equality of an hyper-volume ordered integral to an hyper-surface ordered integral on the border of that hyper-volu...

  19. Wilson loop invariants from WN conformal blocks

    Directory of Open Access Journals (Sweden)

    Oleg Alekseev

    2015-12-01

    Full Text Available Knot and link polynomials are topological invariants calculated from the expectation value of loop operators in topological field theories. In 3D Chern–Simons theory, these invariants can be found from crossing and braiding matrices of four-point conformal blocks of the boundary 2D CFT. We calculate crossing and braiding matrices for WN conformal blocks with one component in the fundamental representation and another component in a rectangular representation of SU(N, which can be used to obtain HOMFLY knot and link invariants for these cases. We also discuss how our approach can be generalized to invariants in higher-representations of WN algebra.

  20. Loop quasi-invariant chunk detection

    DEFF Research Database (Denmark)

    Moyen, Jean-Yves; Rubiano, Thomas; Seiller, Thomas

    2017-01-01

    Several techniques for analysis and transformations are used in compilers. Among them, the peeling of loops for hoisting quasi-invariants can be used to optimize generated code, or simply ease developers’ lives. In this paper, we introduce a new concept of dependency analysis borrowed from...... the computational complexity of the overall program can be decreased. In this paper, we introduce the theory around this concept and present a prototype analysis pass implemented on LLVM. We already implemented a proof of concept on a toy C parser (https://github.com/ThomasRuby/LQICM_On_C_Toy_Parser) analysing...

  1. Design of a liquid metal target loop for a high power spallation

    CERN Document Server

    Andreas Vetter (PSI)

    Diplomarbeit zur Erlangung des Grades Diplom-IngenieurTechnische Universität BerlinThis thesis shows the lay-out of the liquid metal loop, which is designed to evacuate 3.0 MW of thermal power. It describes the function and sizing of the piping and components. The thesis deals with the choice of the pump, the expansion tank/gas separator and the heat exchanger using water as cooling fluid as well as instrumentation.

  2. Closing the Food Systems Loop: Leveraging Social Sciences to Improve Organic Waste Policy

    OpenAIRE

    Geislar, Sally

    2016-01-01

    Urban food waste in the U.S. is almost exclusively bound for landfills, with significant environmental and the economic consequences. Contrary to this linear flow, cities across the developed world are implementing organics collection programs (OCP) that transform waste into a resource. These systems convert excess food into inputs (e.g. biofuel or soil amendment) for other processes (i.e. food and energy production, water reclamation) thereby approximating naturally occurring closed-loop nu...

  3. Nanoscale dislocation shear loops at static equilibrium and finite temperature

    Science.gov (United States)

    Dang, Khanh; Capolungo, Laurent; Spearot, Douglas E.

    2017-12-01

    Atomistic simulations are used to determine the resolved shear stress necessary for equilibrium and the resulting geometry of nanoscale dislocation shear loops in Al. Dislocation loops with different sizes and shapes are created via superposition of elemental triangular dislocation displacement fields in the presence of an externally imposed shear stress. First, a bisection algorithm is developed to determine systematically the resolved shear stress necessary for equilibrium at 0 K. This approach allows for the identification of dislocation core structure and a correlation between dislocation loop size, shape and the computed shear stress for equilibrium. It is found, in agreement with predictions made by Scattergood and Bacon, that the equilibrium shape of a dislocation loop becomes more circular with increasing loop size. Second, the bisection algorithm is extended to study the influence of temperature on the resolved shear stress necessary for stability. An approach is presented to compute the effective lattice friction stress, including temperature dependence, for dislocation loops in Al. The temperature dependence of the effective lattice friction stress can be reliably computed for dislocation loops larger than 16.2 nm. However, for dislocation loops smaller than this threshold, the effective lattice friction stress shows a dislocation loop size dependence caused by significant overlap of the stress fields on the interior of the dislocation loops. Combined, static and finite temperature atomistic simulations provide essential data to parameterize discrete dislocation dynamics simulations.

  4. Molecular simulation studies of monovalent counterion-mediated interactions in a model RNA kissing loop.

    Science.gov (United States)

    Chen, Alan A; Draper, David E; Pappu, Rohit V

    2009-07-24

    A kissing loop is a highly stable complex formed by loop-loop base-pairing between two RNA hairpins. This common structural motif is utilized in a wide variety of RNA-mediated processes, including antisense recognition, substrate recognition in riboswitches, and viral replication. Recent work has shown that the Tar-Tar(*) complex, an archetypal kissing loop, can form without Mg(2+), so long as high concentrations of alkali chloride salts are present. Interestingly, the stability of the complex is found to decrease with increasing cation size. In this work, we used molecular simulations to develop a molecular-level understanding of the origins of the observed counterion specificity. The ionic atmosphere of the Tar-Tar(*) complex was examined in the presence of 800 mm (where m denotes molality) NaCl, KCl, or CsCl. We used spatial free-energy density profiles to analyze differences in counterion accumulation at different spatial extents from the RNA molecule. We found that the lowest free-energy levels, which are situated in the vicinity of the loop-loop interface, can accommodate roughly two counterions, irrespective of counterion type. However, as we moved into higher free-energy levels, which are farther from the loop-loop interface, we observed increased differences in the numbers of accumulated counterions, with this number being largest for Na(+) and smallest for Cs(+). We analyzed the source of these differences and were able to attribute these to two distinct features: The extent of partial dehydration varies based on cation type; the smaller the cation, the greater the degree of dehydration. While smaller ions bind their first-hydration-shell water molecules more tightly than larger ions, they are also able to shed these water molecules for stronger electrostatic interactions with the RNA molecule. Secondly, we observed a distinct asymmetry in the numbers of accumulated cations around each hairpin in the Tar-Tar(*) complex. We were able to ascribe this

  5. Quantum hysteresis loops in microscopic system: The loop area as a ...

    Indian Academy of Sciences (India)

    Quantum hysteresis; stochastic resonance; quantum dynamics; Fourier grid methods; stochastically perturbed systems. ... That means we make use of pure state dynamical description of our quantum system. Let the quantum system be .... Apparently, it breaks into a number of smaller loops. The total enclosed area, ...

  6. Innovative hybrid pile oscillator technique in the Minerve reactor: open loop vs. closed loop

    Directory of Open Access Journals (Sweden)

    Geslot Benoit

    2018-01-01

    Full Text Available Pile oscillator techniques are powerful methods to measure small reactivity worth of isotopes of interest for nuclear data improvement. This kind of experiments has long been implemented in the Mineve experimental reactor, operated by CEA Cadarache. A hybrid technique, mixing reactivity worth estimation and measurement of small changes around test samples is presented here. It was made possible after the development of high sensitivity miniature fission chambers introduced next to the irradiation channel. A test campaign, called MAESTRO-SL, took place in 2015. Its objective was to assess the feasibility of the hybrid method and investigate the possibility to separate mixed neutron effects, such as fission/capture or scattering/capture. Experimental results are presented and discussed in this paper, which focus on comparing two measurements setups, one using a power control system (closed loop and another one where the power is free to drift (open loop. First, it is demonstrated that open loop is equivalent to closed loop. Uncertainty management and methods reproducibility are discussed. Second, results show that measuring the flux depression around oscillated samples provides valuable information regarding partial neutron cross sections. The technique is found to be very sensitive to the capture cross section at the expense of scattering, making it very useful to measure small capture effects of highly scattering samples.

  7. Innovative hybrid pile oscillator technique in the Minerve reactor: open loop vs. closed loop

    Science.gov (United States)

    Geslot, Benoit; Gruel, Adrien; Bréaud, Stéphane; Leconte, Pierre; Blaise, Patrick

    2018-01-01

    Pile oscillator techniques are powerful methods to measure small reactivity worth of isotopes of interest for nuclear data improvement. This kind of experiments has long been implemented in the Mineve experimental reactor, operated by CEA Cadarache. A hybrid technique, mixing reactivity worth estimation and measurement of small changes around test samples is presented here. It was made possible after the development of high sensitivity miniature fission chambers introduced next to the irradiation channel. A test campaign, called MAESTRO-SL, took place in 2015. Its objective was to assess the feasibility of the hybrid method and investigate the possibility to separate mixed neutron effects, such as fission/capture or scattering/capture. Experimental results are presented and discussed in this paper, which focus on comparing two measurements setups, one using a power control system (closed loop) and another one where the power is free to drift (open loop). First, it is demonstrated that open loop is equivalent to closed loop. Uncertainty management and methods reproducibility are discussed. Second, results show that measuring the flux depression around oscillated samples provides valuable information regarding partial neutron cross sections. The technique is found to be very sensitive to the capture cross section at the expense of scattering, making it very useful to measure small capture effects of highly scattering samples.

  8. Improved arrhythmia detection in implantable loop recorders

    DEFF Research Database (Denmark)

    Brignole, M.; Black, C.L.B.; Sutton, R.

    2008-01-01

    Improved Arrhythmia Detection. Introduction: Implantable loop recorders (ILR) have an automatic arrhythmia detection feature that can be compromised by inappropriately detected episodes. This study evaluated a new ILR sensing and detection scheme for automatically detecting asystole, bradyarrhyth......Improved Arrhythmia Detection. Introduction: Implantable loop recorders (ILR) have an automatic arrhythmia detection feature that can be compromised by inappropriately detected episodes. This study evaluated a new ILR sensing and detection scheme for automatically detecting asystole......, bradyarrhythmia, and tachyarrhythmia events, which is implemented in the next generation device (Reveal DX/XT). Methods and Results: The new scheme employs an automatically adjusting R-wave sensing threshold, enhanced noise rejection, and algorithms to detect asystole, bradyarrhythmia, and tachyarrhythmia....... Performance of the new algorithms was evaluated using 2,613 previously recorded, automatically detected Reveal Plus episodes from 533 patients. A total of 71.9% of episodes were inappropriately detected by the original ILR, and at least 88.6% of patients had one or more inappropriate episodes, with most...

  9. Massive loop corrections for collider physics

    Energy Technology Data Exchange (ETDEWEB)

    Yundin, Valery

    2012-02-01

    In this thesis we discuss the problem of evaluation of tensor integrals appearing in a typical one-loop Feynman diagram calculation. We present a computer library for the numerical evaluation of tensor integrals with up to 5 legs and arbitrary kinematics. The code implements algorithms based on the formalism which avoids the appearance of inverse Gram determinants in the reduction of pentagon diagrams. The Gram determinants of box integrals are isolated in the set of new basis integrals by using dimensional recurrence relations. These integrals are then evaluated by dimensional recurrence or expansion in small Gram determinant, which is improved by Pade extrapolation. A cache system allows reuse of identical building blocks and increases the efficiency. After describing the cross checks and accuracy tests, we show a sample application to the evaluation of five gluon helicity amplitudes, which is compared with the output of the program NGluon. In the last part the program is applied to the calculation of the one-loop virtual corrections to the muon pair production with hard photon emission. The computation method is explained, followed by a discussion of renormalization and pole structure. Finally, we present numerical results for differential cross sections with kinematics of the KLOE and BaBar detectors.

  10. Black holes in loop quantum gravity

    Science.gov (United States)

    Perez, Alejandro

    2017-12-01

    This is a review of results on black hole physics in the context of loop quantum gravity. The key feature underlying these results is the discreteness of geometric quantities at the Planck scale predicted by this approach to quantum gravity. Quantum discreteness follows directly from the canonical quantization prescription when applied to the action of general relativity that is suitable for the coupling of gravity with gauge fields, and especially with fermions. Planckian discreteness and causal considerations provide the basic structure for the understanding of the thermal properties of black holes close to equilibrium. Discreteness also provides a fresh new look at more (at the moment) speculative issues, such as those concerning the fate of information in black hole evaporation. The hypothesis of discreteness leads, also, to interesting phenomenology with possible observational consequences. The theory of loop quantum gravity is a developing program; this review reports its achievements and open questions in a pedagogical manner, with an emphasis on quantum aspects of black hole physics.

  11. Black holes in loop quantum gravity.

    Science.gov (United States)

    Perez, Alejandro

    2017-12-01

    This is a review of results on black hole physics in the context of loop quantum gravity. The key feature underlying these results is the discreteness of geometric quantities at the Planck scale predicted by this approach to quantum gravity. Quantum discreteness follows directly from the canonical quantization prescription when applied to the action of general relativity that is suitable for the coupling of gravity with gauge fields, and especially with fermions. Planckian discreteness and causal considerations provide the basic structure for the understanding of the thermal properties of black holes close to equilibrium. Discreteness also provides a fresh new look at more (at the moment) speculative issues, such as those concerning the fate of information in black hole evaporation. The hypothesis of discreteness leads, also, to interesting phenomenology with possible observational consequences. The theory of loop quantum gravity is a developing program; this review reports its achievements and open questions in a pedagogical manner, with an emphasis on quantum aspects of black hole physics.

  12. Thermohaline feedback loops and Natural Capital

    Directory of Open Access Journals (Sweden)

    Tom Sawyer Hopkins

    2001-12-01

    Full Text Available Human interference now represents an inextricable component of all major ecosystems. Whether this is through top-down overharvesting of ecosystem production or bottom-up alteration (deliberate or inadvertent of the abiotic conditions, the planet´s ecosphere is in a vicious degradation cycle. For our economy to shift from exploiting to sustaining the natural systems, the solution, if there is to be one, will involve incorporation of the value of natural capital into the economic and political feedback loop. For the science sector, this will involve developing methodologies to evaluate the nonlinear and behavioral dynamics of entire systems in ways that can be coupled with economic models. One essential characteristic of systems science involves the interactions between internal components and external systems. Thermohaline circulations and their feedback loops illustrate a class of such interactive pathways. Examples from the Arctic, Mediterranean, and the US East Coast along with some of their associated ecological impacts are reviewed. Understanding how thermohaline interactions provide stability to the marine biotic environment and under what conditions this stability could be destabilized is a fundamental step toward evaluating the non-linear response of marine systems to anthropogenic stress.

  13. Keeping Energy Savings in the LOOP

    Energy Technology Data Exchange (ETDEWEB)

    Parrish, Kristen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mercado, Andrea [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-11-01

    Mesa Lane Partners (MLP) partnered with the U.S. Department of Energy (DOE) to develop and implement solutions to a build a new, low-energy mixed-use building that consumes at least 50% less energy than requirements set by Energy Standard 90.1-2007 of the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE), the American National Standards Institute (ANSI), and the Illuminating Engineering Society of America (IESNA), as part of DOE’s Commercial Building Partnerships (CBP)3 Program. Lawrence Berkeley National Laboratory (LBNL) provided technical expertise in support of this DOE program. The privately developed 46,000-square-foot LOOP project, which is intended to provide affordable off-campus student housing in an underserved community next to University of California at Santa Barbara, will contain more than 7,000 square feet of retail space, a roof deck, an event space, a gym, and 48 apartments. The project developer, MLP, is aiming to exceed CBP requirement, targeting energy consumption that is at least 65% less than that required by the standard. If the LOOP meets this goal, it is expected to achieve Leadership in Energy and Environmental Design (LEED) Gold certification. To meet this goal, the project design incorporates a variety of energy efficiency measures (EEMs) that address the needs of the multiple use types that the project will house.

  14. Loop-Effects in Pseudo-Supersymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Matthias

    2002-11-01

    We analyze the transmission of supersymmetry breaking in brane-world models of pseudo-supersymmetry. In these models two branes preserve different halves of the bulk supersymmetry. Thus supersymmetry is broken although each sector of the model is supersymmetric when considered separately. The world-volume theory on one brane feels the breakdown of supersymmetry only through two-loop interactions involving a coupling to fields from the other brane. In a 5D toy model with bulk vectors, we compute the diagrams that contribute to scalar masses on one brane and find that the masses are proportional to the compactification scale up to logarithmic corrections, m{sup 2} {infinity} (2{pi}R){sup -2} (ln(2{pi}R m{sub S}) - 1.1), where m{sub s} is an ultraviolet cutoff. Thus, for large compactification radii, where this result is valid, the brane scalars acquire a positive mass squared. We also compute the three-loop diagrams relevant to the Casimir energy between the two branes and find E {infinity} (2{pi}R){sup -4}((ln(2{pi}R m{sub S}) - 1.7){sup 2} + 0.2). For large radii, this yields a repulsive Casimir force.

  15. Gravity Effects on the Performance of a Flat Loop Heat Pipe

    Science.gov (United States)

    Mo, Dong-Chuan; Ding, Nan; Lu, Shu-Shen

    2009-08-01

    A loop heat pipe with flat evaporator (FLHP) is manufactured from copper, and filled with ultrapure water as the working fluid. The heat transfer characteristics have been studied experimentally. The gravity impacts the heat transfer characteristics of the FLHP in different orientations. Operation of the FLHP at orientations against the gravity which is the evaporator above the condenser leads to the higher temperature of the evaporator and the lower loop heat tranfer performance. At horizontal orientation with the evaporator above the compensation chamber (CC), the working fluid is difficult to reach the wick and has the highest temperature. With the increasing of the heat load upto more than 300 W, the loop thermal resistance decreases and approaches a minimum value of about 0.2 K/W at the vertical orientation helped by gravity. Experimental results show that the start-up with low power needs a temperature overshoot. Oscillations with high frequency (with periods on the order of seconds to minutes) and high amplitude (with temperature changes on the order of tens degree Kelvin) are observed. A model is developed, which shows the working fluid distributing in the evaporator wick may result such oscillations. In most cases, the highest amplitude in the loop is observed in the liquid line near CC, and the lowest amplitude is in the CC.

  16. Loop variants of the thermophile Rasamsonia emersonii Cel7A with improved activity against cellulose.

    Science.gov (United States)

    Sørensen, Trine Holst; Windahl, Michael Skovbo; McBrayer, Brett; Kari, Jeppe; Olsen, Johan Pelck; Borch, Kim; Westh, Peter

    2017-01-01

    Cel7A cellobiohydrolases perform processive hydrolysis on one strand of cellulose, which is threaded through the enzyme's substrate binding tunnel. The tunnel structure results from a groove in the catalytic domain, which is covered by a number of loops. These loops have been identified as potential targets for engineering of this industrially important enzyme family, but only few systematic studies on this have been made. Here we show that two asparagine residues (N194 and N197) positioned in the loop covering the glucopyranose subsite -4 (recently denoted B2 loop) of the thermostable Cel7A from Rasamsonia emersonii had profound effects on both substrate interactions and catalytic efficacy. At room temperature the double mutant N194A/N197A showed strongly reduced substrate affinity with a water-cellulose partitioning coefficient threefold lower than the wild type. Yet, this variant was catalytically efficient with a maximal turnover about twice as high as the wild type. Analogous but smaller changes were found for the single mutants. Analysis of these changes in affinity and kinetics as a function of temperature, led to the conclusion that replacement of N194 and particularly N197 with alanine leads to faster enzyme-substrate dissociation. Conversely, these residues appeared to have little or no effect on the rate of association. We suggest that the controlled adjustment of the enzyme-substrate dissociation prompts faster cellulolytic enzymes. Biotechnol. Bioeng. 2017;114: 53-62. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  17. Theoretical study on a solar collector loop during stagnation

    DEFF Research Database (Denmark)

    Chen, Ziqian; Dragsted, Janne; Furbo, Simon

    A mathematical model simulating the stagnation behavior of a pressurized solar collector loop with solar collectors with a good emptying behavior is developed. Based on the pre-pressure of the expansion vessel, the system filling pressure of the solar collector loop and the design of the solar...... collector loop, the mass of the fluid flowing into the pressurized expansion vessel and the pressures at the top part and at the bottom part of the solar collector loop during stagnation for the solar collector loop are calculated. The theoretically calculated results are compared with experimental results....... There is a good agreement between calculations and measurements. The developed simulation model is therefore suitable to determine the behavior of solar collector loops during stagnation....

  18. High Dynamic Optimized Carrier Loop Improvement for Tracking Doppler Rates

    Directory of Open Access Journals (Sweden)

    Amirhossein Fereidountabar

    2015-01-01

    Full Text Available Mathematical analysis and optimization of a carrier tracking loop are presented. Due to fast changing of the carrier frequency in some satellite systems, such as Low Earth Orbit (LEO or Global Positioning System (GPS, or some planes like Unmanned Aerial Vehicles (UAVs, high dynamic tracking loops play a very important role. In this paper an optimized tracking loop consisting of a third-order Phase Locked Loop (PLL assisted by a second-order Frequency Locked Loop (FLL for UAVs is proposed and discussed. Based on this structure an optimal loop has been designed. The main advantages of this approach are the reduction of the computation complexity and smaller phase error. The paper shows the simulation results, comparing them with a previous work.

  19. Coronal Loop Evolution Observed with AIA and Hi-C

    Science.gov (United States)

    Mulu-Moore, Fana; Winebarger, A.; Cirtain, J.; Kobayashi, K.; Korreck, K.; Golub, L.; Kuzin. S.; Walsh, R.; DeForest, C.; DePontieu, B.; hide

    2012-01-01

    Despite much progress toward understanding the dynamics of the solar corona, the physical properties of coronal loops are not yet fully understood. Recent investigations and observations from different instruments have yielded contradictory results about the true physical properties of coronal loops. In the past, the evolution of loops has been used to infer the loop substructure. With the recent launch of High Resolution Coronal Imager (Hi-C), this inference can be validated. In this poster we discuss the first results of loop analysis comparing AIA and Hi-C data. We find signatures of cooling in a pixel selected along a loop structure in the AIA multi-filter observations. However, unlike previous studies, we find that the cooling time is much longer than the draining time. This is inconsistent with previous cooling models.

  20. Tree-loop duality relation beyond single poles

    Energy Technology Data Exchange (ETDEWEB)

    Bierenbaum, Isabella [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Buchta, Sebastian; Draggiotis, Petros; Malamos, Ioannis; Rodrigo, German [Valencia Univ. Paterna (Spain). Inst. de Fisica Corpuscular

    2012-11-15

    We develop the Tree-Loop Duality Relation for two- and three-loop integrals with multiple identical propagators (multiple poles). This is the extension of the Duality Relation for single poles and multi-loop integrals derived in previous publications. We prove a generalization of the formula for single poles to multiple poles and we develop a strategy for dealing with higher-order pole integrals by reducing them to single pole integrals using Integration By Parts.

  1. The Energy Landscape of Hyperstable LacI-DNA Loops

    Science.gov (United States)

    Kahn, Jason

    2009-03-01

    The Escherichia coli LacI protein represses transcription of the lac operon by blocking access to the promoter through binding at a promoter-proximal DNA operator. The affinity of tetrameric LacI (and therefore the repression efficiency) is enhanced by simultaneous binding to an auxiliary operator, forming a DNA loop. Hyperstable LacI-DNA loops were previously shown to be formed on DNA constructs that include a sequence-directed bend flanked by operators. Biochemical experiments showed that two such constructs (9C14 and 11C12) with different helical phasing between the operators and the DNA bend form different DNA loop shapes. The geometry and topology of the loops and the relevance of alternative conformations suggested by probable flexible linkers in LacI remain unclear. Bulk and single molecule fluorescence resonance energy transfer (SM-FRET, with D. English) experiments on a dual fluorophore-labeled 9C14-LacI loop demonstrate that it adopts a single, stable, rigid closed-form loop conformation. Here, we characterize the LacI-9C14 loop by SM-FRET as a function of inducer isopropyl-β,D-thiogalactoside (IPTG) concentration. Energy transfer measurements reveal partial but incomplete destabilization of loop formation by IPTG. Surprisingly, there is no change in the energy transfer efficiency of the remaining looped population. Models for the regulation of the lac operon often assume complete disruption of LacI-operator complexes upon inducer binding to LacI. Our work shows that even at saturating IPTG there is still a significant population of LacI-DNA complexes in a looped state, in accord with previous in vivo experiments that show incomplete induction (with J. Maher). Finally, we will report progress on characterizing the ``energy landscape'' for DNA looping upon systematic variation of the DNA linkers between the operators and the bending locus. Rod mechanics simulations (with N. Perkins) provide testable predictions on loop stability, topology, and FRET.

  2. The Quantum Configuration Space of Loop Quantum Cosmology

    OpenAIRE

    Velhinho, J. M.

    2007-01-01

    The article gives an account of several aspects of the space known as the Bohr compactification of the line, featuring as the quantum configuration space in loop quantum cosmology, as well as of the corresponding configuration space realization of the so-called polymer representation. Analogies with loop quantum gravity are explored, providing an introduction to (part of) the mathematical structure of loop quantum gravity, in a technically simpler context.

  3. The quantum configuration space of loop quantum cosmology

    Science.gov (United States)

    Velhinho, J. M.

    2007-07-01

    This paper gives an account of several aspects of the space known as the Bohr compactification of the line, featuring as the quantum configuration space in loop quantum cosmology, as well as of the corresponding configuration space realization of the so-called polymer representation. Analogies with loop quantum gravity are explored, providing an introduction to (part of) the mathematical structure of loop quantum gravity, in a technically simpler context.

  4. Exploiting loop level parallelism in nonprocedural dataflow programs

    Science.gov (United States)

    Gokhale, Maya B.

    1987-01-01

    Discussed are how loop level parallelism is detected in a nonprocedural dataflow program, and how a procedural program with concurrent loops is scheduled. Also discussed is a program restructuring technique which may be applied to recursive equations so that concurrent loops may be generated for a seemingly iterative computation. A compiler which generates C code for the language described below has been implemented. The scheduling component of the compiler and the restructuring transformation are described.

  5. Direct-contact closed-loop heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Berry, Gregory F. (Naperville, IL); Minkov, Vladimir (Skokie, IL); Petrick, Michael (Joliet, IL)

    1984-01-01

    A high temperature heat exchanger with a closed loop and a heat transfer liquid within the loop, the closed loop having a first horizontal channel with inlet and outlet means for providing direct contact of a first fluid at a first temperature with the heat transfer liquid, a second horizontal channel with inlet and outlet means for providing direct contact of a second fluid at a second temperature with the heat transfer liquid, and means for circulating the heat transfer liquid.

  6. Ladder exponentiation for generic large symmetric representation Wilson loops

    OpenAIRE

    Correa, Diego; Massolo, Fidel(Instituto de Física La Plata, CONICET, Universidad Nacional de La Plata, C.C. 67, La Plata, 1900, Argentina)

    2015-01-01

    A recent proposal was made for a large representation rank limit for which the expectation values of N = 4 $$ \\mathcal{N}=4 $$ super Yang-Mills Wilson loops are given by the exponential of the 1-loop result. We verify the validity of this exponentiation in the strong coupling limit using the holographic D3-brane description for straight Wilson loops following an arbitrary internal space trajectory.

  7. Minor magnetization loops in two-dimensional dipolar Ising model

    Energy Technology Data Exchange (ETDEWEB)

    Sarjala, M. [Aalto University, Department of Applied Physics, P.O. Box 14100, FI-00076 Aalto (Finland); Seppaelae, E.T., E-mail: eira.seppala@nokia.co [Nokia Research Center, Itaemerenkatu 11-13, FI-00180 Helsinki (Finland); Alava, M.J., E-mail: mikko.alava@tkk.f [Aalto University, Department of Applied Physics, P.O. Box 14100, FI-00076 Aalto (Finland)

    2011-05-15

    The two-dimensional dipolar Ising model is investigated for the relaxation and dynamics of minor magnetization loops. Monte Carlo simulations show that in a stripe phase an exponential decrease can be found for the magnetization maxima of the loops, M{approx}exp(-{alpha}N{sub l}) where N{sub l} is the number of loops. We discuss the limits of this behavior and its relation to the equilibrium phase diagram of the model.

  8. 76 FR 56493 - Notice of Final Federal Agency Actions on State Loop 375 From Interstate Highway 10 to the...

    Science.gov (United States)

    2011-09-13

    ... Conservation Fund (LWCF), 16 U.S.C. 4601-4604; Safe Drinking Water Act (SDWA), 42 U.S.C. 300(f)-300(j)(6... Interstate Highway 10 to the Franklin Mountains State Park in Texas AGENCY: Federal Highway Administration..., upgrades to Texas State Loop 375 from Interstate Highway 10 to 0.479 Mile East of the Tom Mays Unit of the...

  9. Impact of looping on middle school science standardized achievement tests

    Science.gov (United States)

    Barger, Tammy M.

    Looping may be defined as a teacher remaining with a group of students for multiple academic years. In this quantitative study, looping was examined as a factor on science achievement. State-wide eighth grade school level 2010 Pennsylvania System of School Assessment (PSSA) data were used. By responding to a mailing, school administrators indicated if 2010 eighth grade students had or had not been looped. The schools' percentage of advanced and proficient Science PSSA data were used to determine if the independent variable had a significant impact on science achievement. The results of the independent t-test analysis suggest that looping does not contribute to science achievement for this study sample.

  10. Dynamics of closed-loop systems containing flexible bodies

    Science.gov (United States)

    Tadikonda, Sivakumar S. K.; Singh, Ramendra P.

    1991-01-01

    An important characteristic of flexible multibody systems containing closed-loop topologies is that the component modes used to describe individual bodies will no longer be independent because of loop closure constraints. Thus, the issue of component modal selection becomes even more complicated. In addition, the foreshortening effect that has been studied extensively in the literature in the context of open-loop topologies will also be present in these constraint equations. Simulation results presented demonstrate the effects of modal selection and foreshortening on the dynamic response of closed-loop flexible systems.

  11. Multi-loop Integrand Reduction with Computational Algebraic Geometry

    CERN Document Server

    Badger, Simon; Zhang, Yang

    2014-01-01

    We discuss recent progress in multi-loop integrand reduction methods. Motivated by the possibility of an automated construction of multi-loop amplitudes via generalized unitarity cuts we describe a procedure to obtain a general parameterisation of any multi-loop integrand in a renormalizable gauge theory. The method relies on computational algebraic geometry techniques such as Gr\\"obner bases and primary decomposition of ideals. We present some results for two and three loop amplitudes obtained with the help of the Macaulay2 computer algebra system and the Mathematica package BasisDet.

  12. Two-loop off-shell QCD amplitudes in FDR

    CERN Document Server

    Page, Ben

    2015-01-01

    We link the FDR treatment of ultraviolet (UV) divergences to dimensional regularization up to two loops in QCD. This allows us to derive the one-loop and two-loop coupling constant and quark mass shifts necessary to translate infrared finite quantities computed in FDR to the MSbar renormalization scheme. As a by-product of our analysis, we solve a problem analogous to the breakdown of unitarity in the Four Dimensional Helicity (FDH) method beyond one loop. A fix to FDH is then presented that preserves the renormalizability properties of QCD without introducing evanescent quantities.

  13. Enhanced Loop Structure of NFC Antenna for Mobile Handset Applications

    Directory of Open Access Journals (Sweden)

    Byungje Lee

    2014-01-01

    Full Text Available A new structure of an NFC loop antenna for mobile handset applications is proposed. The proposed antenna consists of conventional loop elements and a parasitic loop embedded capacitor to enhance its performance. Although the sintered ferrite sheets with higher relative permeability (μr≈200 have been used to reduce the performance deterioration due to the eddy current on the battery pack of a mobile handset, their costs are high, and they are considerably breakable. In this paper, with the proposed structure, we effectively enhance the performance of an NFC loop antenna by employing the ferrite-polymer composite with lower relative permeability (μr≈55.

  14. Lattice corrections to the quark quasidistribution at one loop

    Science.gov (United States)

    Carlson, Carl E.; Freid, Michael

    2017-05-01

    We calculate radiative corrections to the quark quasidistribution in lattice perturbation theory at one loop to leading orders in the lattice spacing. We also consider one-loop corrections in continuum Euclidean space. We find that the infrared behavior of the corrections in Euclidean and Minkowski space are different. We explore features of momentum loop integrals and demonstrate why loop corrections from the lattice perturbation theory and Euclidean continuum do not correspond with their Minkowski brethren, and comment on a recent suggestion for transcending the differences in the results. Further, we examine the role of the lattice spacing a and of the r parameter in the Wilson action in these radiative corrections.

  15. Inverse spin Hall effect in a closed loop circuit

    Energy Technology Data Exchange (ETDEWEB)

    Omori, Y.; Auvray, F.; Wakamura, T.; Niimi, Y., E-mail: niimi@issp.u-tokyo.ac.jp [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8581 (Japan); Fert, A. [Unité Mixte de Physique CNRS/Thales, 91767 Palaiseau France associée à l' Université de Paris-Sud, 91405 Orsay (France); Otani, Y. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8581 (Japan); RIKEN-CEMS, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2014-06-16

    We present measurements of inverse spin Hall effects (ISHEs), in which the conversion of a spin current into a charge current via the ISHE is detected not as a voltage in a standard open circuit but directly as the charge current generated in a closed loop. The method is applied to the ISHEs of Bi-doped Cu and Pt. The derived expression of ISHE for the loop structure can relate the charge current flowing into the loop to the spin Hall angle of the SHE material and the resistance of the loop.

  16. R-loops: targets for nuclease cleavage and repeat instability.

    Science.gov (United States)

    Freudenreich, Catherine H

    2018-01-11

    R-loops form when transcribed RNA remains bound to its DNA template to form a stable RNA:DNA hybrid. Stable R-loops form when the RNA is purine-rich, and are further stabilized by DNA secondary structures on the non-template strand. Interestingly, many expandable and disease-causing repeat sequences form stable R-loops, and R-loops can contribute to repeat instability. Repeat expansions are responsible for multiple neurodegenerative diseases, including Huntington's disease, myotonic dystrophy, and several types of ataxias. Recently, it was found that R-loops at an expanded CAG/CTG repeat tract cause DNA breaks as well as repeat instability (Su and Freudenreich, Proc Natl Acad Sci USA 114, E8392-E8401, 2017). Two factors were identified as causing R-loop-dependent breaks at CAG/CTG tracts: deamination of cytosines and the MutLγ (Mlh1-Mlh3) endonuclease, defining two new mechanisms for how R-loops can generate DNA breaks (Su and Freudenreich, Proc Natl Acad Sci USA 114, E8392-E8401, 2017). Following R-loop-dependent nicking, base excision repair resulted in repeat instability. These results have implications for human repeat expansion diseases and provide a paradigm for how RNA:DNA hybrids can cause genome instability at structure-forming DNA sequences. This perspective summarizes mechanisms of R-loop-induced fragility at G-rich repeats and new links between DNA breaks and repeat instability.

  17. Finding the positive feedback loops underlying multi-stationarity.

    Science.gov (United States)

    Feliu, Elisenda; Wiuf, Carsten

    2015-05-28

    Bistability is ubiquitous in biological systems. For example, bistability is found in many reaction networks that involve the control and execution of important biological functions, such as signaling processes. Positive feedback loops, composed of species and reactions, are necessary for bistability, and generally for multi-stationarity, to occur. These loops are therefore often used to illustrate and pinpoint the parts of a multi-stationary network that are relevant ('responsible') for the observed multi-stationarity. However positive feedback loops are generally abundant in reaction networks but not all of them are important for understanding the network's dynamics. We present an automated procedure to determine the relevant positive feedback loops of a multi-stationary reaction network. The procedure only reports the loops that are relevant for multi-stationarity (that is, when broken multi-stationarity disappears) and not all positive feedback loops of the network. We show that the relevant positive feedback loops must be understood in the context of the network (one loop might be relevant for one network, but cannot create multi-stationarity in another). Finally, we demonstrate the procedure by applying it to several examples of signaling processes, including a ubiquitination and an apoptosis network, and to models extracted from the Biomodels database. The procedure is implemented in Maple. We have developed and implemented an automated procedure to find relevant positive feedback loops in reaction networks. The results of the procedure are useful for interpretation and summary of the network's dynamics.

  18. Comments on Pinched Hysteresis Loops of Memristive Elements

    Directory of Open Access Journals (Sweden)

    Z. Biolek

    2015-12-01

    Full Text Available The hysteresis loops pinched in the v-i origin belong to well-known fingerprints of memristive elements driven by bipolar periodical signals. Some element properties follow from the loop behavior in the close neighborhood of the origin. The paper analyzes this behavior of the memristive elements that produce steady-state hysteresis loops under harmonic excitation. It is shown that there is a connection between the frequency content of the state variable waveform and the type of the loop being pinched.

  19. Loop Entropy Assists Tertiary Order: Loopy Stabilization of Stacking Motifs

    Directory of Open Access Journals (Sweden)

    Daniel P. Aalberts

    2011-11-01

    Full Text Available The free energy of an RNA fold is a combination of favorable base pairing and stacking interactions competing with entropic costs of forming loops. Here we show how loop entropy, surprisingly, can promote tertiary order. A general formula for the free energy of forming multibranch and other RNA loops is derived with a polymer-physics based theory. We also derive a formula for the free energy of coaxial stacking in the context of a loop. Simulations support the analytic formulas. The effects of stacking of unpaired bases are also studied with simulations.

  20. Time Optimal Synchronization Procedure and Associated Feedback Loops

    CERN Document Server

    Angoletta, Maria Elena; CERN. Geneva. ATS Department

    2016-01-01

    A procedure to increase the speed of currently used synchronization loops in a synchrotron by an order of magnitude is presented. Beams dynamics constraint imposes an upper limit on excursions in stable phase angle, and the procedure presented exploits this limit to arrive in the synchronized state from an arbitrary initial state in the fastest possible way. Detailed corrector design for beam phase loop, differential frequency loop and final synchronization loop is also presented. Finally, an overview of the synchronization methods currently deployed in some other CERN’s machines is provided, together with a brief comparison with the newly proposed time-optimal algorithm.

  1. Parallelizing More Loops with Compiler Guided Refactoring

    DEFF Research Database (Denmark)

    Larsen, Per; Ladelsky, Razya; Lidman, Jacob

    2012-01-01

    with target-specific optimizations. Furthermore, comparing the first benchmark to manually-parallelized, handoptimized pthreads and OpenMP versions, we find that code generated using our approach typically outperforms the pthreads code (within 93-339%). It also performs competitively against the OpenMP code...... an interactive compilation feedback system that guides programmers in iteratively modifying their application source code. This helps leverage the compiler’s ability to generate loop-parallel code. We employ our system to modify two sequential benchmarks dealing with image processing and edge detection......, resulting in scalable parallelized code that runs up to 8.3 times faster on an eightcore Intel Xeon 5570 system and up to 12.5 times faster on a quad-core IBM POWER6 system. Benchmark performance varies significantly between the systems. This suggests that semi-automatic parallelization should be combined...

  2. Simple Device for Treating Prolapsing Loop Colostomy

    Directory of Open Access Journals (Sweden)

    Ming-Yu Hsieh

    2006-03-01

    Full Text Available Stoma prolapse is a common complication of intestinal stoma. Although various surgical methods yield satisfactory results, nonsurgical treatment may be better for a temporary stoma. We report a case of a patient with a distal limb prolapse of a right transverse colostomy who received nonsurgical treatment with satisfactory results. For the treatment of a temporary transverse loop colostomy with distal limb prolapse, we designed a simple device consisting of a pediatric plastic medicine cup, which was rolled into a towel to shape the bottom of the cup into a compressor. The towel was put on the stoma outside of the colostomy bag with the compressor above the prolapsing limb of the colostomy. An abdominal binder was applied to fix the towel.

  3. Geothermal Loop Experimental Facility. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1980-04-01

    Research at the Geothermal Loop Experimental Facility was successfully concluded in September 1979. In 13,000 hours of operation over a three and one half year period, the nominal 10 megawatt electrical equivalent GLEF provided the opportunity to identify problems in working with highly saline geothermal fluids and to develop solutions that could be applied to a commercial geothermal power plant producing electricity. A seven and one half year period beginning in April 1972, with early well flow testing and ending in September 1979, with the completion of extensive facility and reservoir operations is covered. During this period, the facility was designed, constructed and operated in several configurations. A comprehensive reference document, addressing or referencing documentation of all the key areas investigated is presented.

  4. ABJM Wilson loops in arbitrary representations

    Energy Technology Data Exchange (ETDEWEB)

    Hatsuda, Yasuyuki [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Tokyo Institute of Technology (Japan). Dept. of Physics; Honda, Masazumi [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Moriyama, Sanefumi [Nagoya Univ. (Japan). Kobayashi Maskawa Inst. and Graduate School of Mathematics; Okuyama, Kazumi [Shinshu Univ., Matsumoto, Nagano (Japan). Dept. of Physics

    2013-06-15

    We study vacuum expectation values (VEVs) of circular half BPS Wilson loops in arbitrary representations in ABJM theory. We find that those in hook representations are reduced to elementary integrations thanks to the Fermi gas formalism, which are accessible from the numerical studies similar to the partition function in the previous studies. For non-hook representations, we show that the VEVs in the grand canonical formalism can be exactly expressed as determinants of those in the hook representations. Using these facts, we can study the instanton effects of the VEVs in various representations. Our results are consistent with the worldsheet instanton effects studied from the topological string and a prescription to include the membrane instanton effects by shifting the chemical potential, which has been successful for the partition function.

  5. Cosmological perturbations in teleparallel Loop Quantum Cosmology

    CERN Document Server

    Haro, Jaime

    2013-01-01

    Cosmological perturbations in Loop Quantum Cosmology (LQC) could be studied from two totally different ways. The first one, called holonomy corrected LQC, is performed in the Hamiltonian framework, where the Asthekar connection is replaced by a suitable sinus function (holonomy correction), in order to have a well-defined quantum analogue. The alternative approach is based in the fact that isotropic LQC could be also obtained as a particular case of teleparallel $F(T)$ gravity (teleparallel LQC). Then, working in the Lagrangian framework and using the well-know perturbation equations in $F(T)$ gravity, we have obtained, in teleparallel LQC, the equations for scalar and tensor perturbations, and the corresponding Mukhanov-Sasaki equations. For scalar perturbations, our equation only differs from the one obtained by holonomy corrections in the velocity of sound, leading both formulations, essentially to the same scale invariant power spectrum when a matter-dominated universe is considered. However for tensor pe...

  6. Effective scenario of loop quantum cosmology.

    Science.gov (United States)

    Ding, You; Ma, Yongge; Yang, Jinsong

    2009-02-06

    Semiclassical states in isotropic loop quantum cosmology are employed to show that the improved dynamics has the correct classical limit. The effective Hamiltonian for the quantum cosmological model with a massless scalar field is thus obtained, which incorporates also the next to leading order quantum corrections. The possibility that the higher order correction terms may lead to significant departure from the leading order effective scenario is revealed. If the semiclassicality of the model is maintained in the large scale limit, there are great possibilities for a k=0 Friedmann expanding universe to undergo a collapse in the future due to the quantum gravity effect. Thus the quantum bounce and collapse may contribute a cyclic universe in the new scenario.

  7. Loops in the Sun’s orbit

    Directory of Open Access Journals (Sweden)

    Marjanov Milutin

    2013-01-01

    Full Text Available Besides translation, spin around its axis and rotation around center of the Milky Way, the Sun performs relative motion in the solar system Laplacian plane, also. This motion was anticipated by Newton himself, in his Principia. The form of the Sun’s orbit is substantially different from the other solar system bodies’ orbits. Namely, the Sun moves along the path composed of the chain of large and small loops [1, 2, 6, 9]. This chain is situated within the circular outline with the diameter approximately twice as large as the Sun’s is. Under supposition that the solar system is stable, the Sun is going to move along it, in the same region, for eternity, never reitereiting the same path. It was also shown in this work that velocity and acceleration of the Sun’s center of mass are completely defined by the relative velocities and accelerations of the planets with respect to the Sun.

  8. Area Law from Loop Quantum Gravity

    CERN Document Server

    Hamma, Alioscia; Marciano, Antonino; Zhang, Mingyi

    2015-01-01

    We explore the constraints following from requiring the Area Law in the entanglement entropy in the context of loop quantum gravity. We find a unique solution to the single link wave-function in the large j limit, believed to be appropriate in the semi-classical limit. We then generalize our considerations to multi-link coherent states, and find that the area law is preserved very generically using our single link wave-function as a building block. Finally, we develop the framework that generates families of multi-link states that preserve the area law while avoiding macroscopic entanglement, the space-time analogue of "Schroedinger cat". We note that these states, defined on a given set of graphs, are the ground states of some local Hamiltonian that can be constructed explicitly. This can potentially shed light on the construction of the appropriate Hamiltonian constraints in the LQG framework.

  9. Looped energy harvester for human motion

    Science.gov (United States)

    Geisler, M.; Boisseau, S.; Gasnier, P.; Willemin, J.; Gobbo, C.; Despesse, G.; Ait-Ali, I.; Perraud, S.

    2017-10-01

    The development of energy harvesters for smart wearables is a challenging topic, with a difficult combination of ergonomics constraints, lifetime and electrical requirements. In this work, we focus on an inertial inductive structure, composed of a magnetic ball circulating inside a closed-loop guide and converting the kinetic energy of the user’s limbs into electricity during the run. A specific induction issue related to the free self-rotation of the ball is underlined and addressed using a ferromagnetic ‘rail’ component. From a 2 g moving ball, a 5 cm-diameter 21 cm3 prototype generated up to 4.8 mW of average power when worn by someone running at 8 km h-1. This device is demonstrated to charge a 2.4 V NiMH battery and supply an acceleration and temperature Wireless Sensor Node at 20 Hz.

  10. Closed loop supply chain in printing operation

    Directory of Open Access Journals (Sweden)

    Marcius Fabius Henriques Carvalho

    2011-12-01

    Full Text Available There is a clear change in focus in large companies, previously dedicated primarily to the production of physical goods, toward offering complimentary services and changing their focus toward more service-oriented businesses, in order to increase their competitiveness. At the same time, companies are facing increasing product returns due to various reasons leading to reverse logistics practices and toward the introduction of a Closed Loop Supply Chain management perspective. The purpose of this work is to identify, using a case study in the printing industry,  specific characteristics, regarding product returns, both in a product-oriented and a service-oriented operation. Furthermore, the current work performs a diagnosis of current practices applications of CLSC models in the two operating models. The paper concludes that indeed there are relevant differences in managing the CLSC for each case and identify the main gaps for each operation.

  11. Subleading soft graviton theorem for loop amplitudes

    Science.gov (United States)

    Sen, Ashoke

    2017-11-01

    Superstring field theory gives expressions for heterotic and type II string loop amplitudes that are free from ultraviolet and infrared divergences when the number of non-compact space-time dimensions is five or more. We prove the subleading soft graviton theorem in these theories to all orders in perturbation theory for S-matrix elements of arbitrary number of finite energy external states but only one external soft graviton. We also prove the leading soft graviton theorem for arbitrary number of finite energy external states and arbitrary number of soft gravitons. Since our analysis is based on general properties of one particle irreducible effective action, the results are valid in any theory of quantum gravity that gives finite result for the S-matrix order by order in perturbation theory without violating general coordinate invariance.

  12. 't Hooft loops and perturbation theory

    CERN Document Server

    De Forcrand, Philippe; Noth, D; Forcrand, Philippe de; Lucini, Biagio; Noth, David

    2005-01-01

    We show that high-temperature perturbation theory describes extremely well the area law of SU(N) spatial 't Hooft loops, or equivalently the tension of the interface between different Z_N vacua in the deconfined phase. For SU(2), the disagreement between Monte Carlo data and lattice perturbation theory for sigma(T)/T^2 is less than 2%, down to temperatures O(10) T_c. For SU(N), N>3, the ratios of interface tensions, (sigma_k/sigma_1)(T), agree with perturbation theory, which predicts tiny deviations from the ratio of Casimirs, down to nearly T_c. In contrast, individual tensions differ markedly from the perturbative expression. In all cases, the required precision Monte Carlo measurements are made possible by a simple but powerful modification of the 'snake' algorithm.

  13. An integrated tool for loop calculations: AITALC

    Science.gov (United States)

    Lorca, Alejandro; Riemann, Tord

    2006-01-01

    AITALC, a new tool for automating loop calculations in high energy physics, is described. The package creates Fortran code for two-fermion scattering processes automatically, starting from the generation and analysis of the Feynman graphs. We describe the modules of the tool, the intercommunication between them and illustrate its use with three examples. Program summaryTitle of the program:AITALC version 1.2.1 (9 August 2005) Catalogue identifier:ADWO Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWO Program obtainable from:CPC Program Library, Queen's University of Belfast, N. Ireland Computer:PC i386 Operating system:GNU/ LINUX, tested on different distributions SuSE 8.2 to 9.3, Red Hat 7.2, Debian 3.0, Ubuntu 5.04. Also on SOLARIS Programming language used:GNU MAKE, DIANA, FORM, FORTRAN77 Additional programs/libraries used:DIANA 2.35 ( QGRAF 2.0), FORM 3.1, LOOPTOOLS 2.1 ( FF) Memory required to execute with typical data:Up to about 10 MB No. of processors used:1 No. of lines in distributed program, including test data, etc.:40 926 No. of bytes in distributed program, including test data, etc.:371 424 Distribution format:tar gzip file High-speed storage required:from 1.5 to 30 MB, depending on modules present and unfolding of examples Nature of the physical problem:Calculation of differential cross sections for ee annihilation in one-loop approximation. Method of solution:Generation and perturbative analysis of Feynman diagrams with later evaluation of matrix elements and form factors. Restriction of the complexity of the problem:The limit of application is, for the moment, the 2→2 particle reactions in the electro-weak standard model. Typical running time:Few minutes, being highly depending on the complexity of the process and the FORTRAN compiler.

  14. Fermions in hybrid loop quantum cosmology

    Science.gov (United States)

    Elizaga Navascués, Beatriz; Mena Marugán, Guillermo A.; Martín-Benito, Mercedes

    2017-08-01

    This work pioneers the quantization of primordial fermion perturbations in hybrid loop quantum cosmology (LQC). We consider a Dirac field coupled to a spatially flat, homogeneous, and isotropic cosmology, sourced by a scalar inflaton, and treat the Dirac field as a perturbation. We describe the inhomogeneities of this field in terms of creation and annihilation variables, chosen to admit a unitary evolution if the Dirac fermion were treated as a test field. Considering instead the full system, we truncate its action at quadratic perturbative order and construct a canonical formulation. In particular this implies that, in the global Hamiltonian constraint of the model, the contribution of the homogeneous sector is corrected with a quadratic perturbative term. We then adopt the hybrid LQC approach to quantize the full model, combining the loop representation of the homogeneous geometry with the Fock quantization of the inhomogeneities. We assume a Born-Oppenheimer ansatz for physical states and show how to obtain a Schrödinger equation for the quantum evolution of the perturbations, where the role of time is played by the homogeneous inflaton. We prove that the resulting quantum evolution of the Dirac field is indeed unitary, despite the fact that the underlying homogeneous geometry has been quantized as well. Remarkably, in such evolution, the fermion field couples to an infinite sequence of quantum moments of the homogeneous geometry. Moreover, the evolved Fock vacuum of our fermion perturbations is shown to be an exact solution of the Schrödinger equation. Finally, we discuss in detail the quantum backreaction that the fermion field introduces in the global Hamiltonian constraint. For completeness, our quantum study includes since the beginning (gauge-invariant) scalar and tensor perturbations, that were studied in previous works.

  15. Spontaneous activity in peripheral diaphragmatic lymphatic loops.

    Science.gov (United States)

    Moriondo, Andrea; Solari, Eleonora; Marcozzi, Cristiana; Negrini, Daniela

    2013-10-01

    The spontaneous contractility of FITC-dextran-filled lymphatics at the periphery of the pleural diaphragm was documented for the first time "in vivo" in anesthetized Wistar rats. We found that lymphatic segments could be divided into four phenotypes: 1) active, displaying rhythmic spontaneous contractions (51.8% of 197 analyzed sites); 2) stretch-activated, whose contraction was triggered by passive distension of the vessel lumen (4.1%); 3) passive, which displayed a completely passive distension (4.5%); and 4) inert, whose diameter never changed over time (39.6%). Smooth muscle actin was detected by immunofluorescence and confocal microscopy in the vessel walls of active but also of inert sites, albeit with a very different structure within the vessel wall. Indeed, while in active segments, actin was arranged in a dense mesh completely surrounding the lumen, in inert segments actin decorated the vessels wall in sparse longitudinal strips. When located nearby along the same lymphatic loop, active, stretch-activated, and passive sites were always recruited in temporal sequence starting from the active contraction. The time delay was ∼0.35 s between active and stretch-activated and 0.54 s between stretch-activated and passive segments, promoting a uniform lymph flux of ∼150/200 pl/min. We conclude that, unlike more central diaphragmatic lymphatic vessels, loops located at the extreme diaphragmatic periphery do require an intrinsic pumping mechanism to propel lymph centripetally, and that such an active lymph propulsion is attained by means of a complex interplay among sites whose properties differ but are indeed able to organize lymph flux in an ordered fashion.

  16. Strategic need for a multi-purpose thermal hydraulic loop for support of advanced reactor technologies

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, James E. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sabharwall, Piyush [Idaho National Lab. (INL), Idaho Falls, ID (United States); Yoon, Su -Jong [Idaho National Lab. (INL), Idaho Falls, ID (United States); Housley, Gregory K. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-09-01

    This report presents a conceptual design for a new high-temperature multi fluid, multi loop test facility for the INL to support thermal hydraulic, materials, and thermal energy storage research for nuclear and nuclear-hybrid applications. In its initial configuration, the facility will include a high-temperature helium loop, a liquid salt loop, and a hot water/steam loop. The three loops will be thermally coupled through an intermediate heat exchanger (IHX) and a secondary heat exchanger (SHX). Research topics to be addressed with this facility include the characterization and performance evaluation of candidate compact heat exchangers such as printed circuit heat exchangers (PCHEs) at prototypical operating conditions, flow and heat transfer issues related to core thermal hydraulics in advanced helium-cooled and salt-cooled reactors, and evaluation of corrosion behavior of new cladding materials and accident-tolerant fuels for LWRs at prototypical conditions. Based on its relevance to advanced reactor systems, the new facility has been named the Advanced Reactor Technology Integral System Test (ARTIST) facility. Research performed in this facility will advance the state of the art and technology readiness level of high temperature intermediate heat exchangers (IHXs) for nuclear applications while establishing the INL as a center of excellence for the development and certification of this technology. The thermal energy storage capability will support research and demonstration activities related to process heat delivery for a variety of hybrid energy systems and grid stabilization strategies. Experimental results obtained from this research will assist in development of reliable predictive models for thermal hydraulic design and safety codes over the range of expected advanced reactor operating conditions. Proposed/existing IHX heat transfer and friction correlations and criteria will be assessed with information on materials compatibility and instrumentation

  17. Two-phase flow patterns recognition and parameters estimation through natural circulation test loop image analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, R.N.; Libardi, R.M.P.; Masotti, P.H.F.; Sabundjian, G.; Andrade, D.A.; Umbehaun, P.E.; Torres, W.M.; Conti, T.N.; Macedo, L.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Nuclear Engineering Center], e-mail: rnavarro@ipen.br

    2009-07-01

    Visualization of natural circulation test loop cycles is used to study two-phase flow patterns associated with phase transients and static instabilities of flow. Experimental studies on natural circulation flow were originally related to accidents and transient simulations relative to nuclear reactor systems with light water refrigeration. In this regime, fluid circulation is mainly caused by a driving force ('thermal head') which arises from density differences due to temperature gradient. Natural circulation phenomenon has been important to provide residual heat removal in cases of 'loss of pump power' or plant shutdown in nuclear power plant accidents. The new generation of compact nuclear reactors includes natural circulation of their refrigerant fluid as a security mechanism in their projects. Two-phase flow patterns have been studied for many decades, and the related instabilities have been object of special attention recently. Experimental facility is an all glass-made cylindrical tubes loop which contains about twelve demineralized water liters, a heat source by an electrical resistor immersion heater controlled by a Variac, and a helicoidal heat exchanger working as cold source. Data is obtained through thermo-pairs distributed over the loop and CCD cameras. Artificial intelligence based algorithms are used to improve (bubble) border detection and patterns recognition, in order to estimate and characterize, phase transitions patterns and correlate them with the periodic static instability (chugging) cycle observed in this circuit. Most of initial results show good agreement with previous numerical studies in this same facility. (author)

  18. Redesign of the Extravehicular Mobility Unit Airlock Cooling Loop Recovery Assembly

    Science.gov (United States)

    Steele, John; Elms, Theresa; Peyton, Barbara; Rector, Tony; Jennings, Mallory

    2016-01-01

    During EVA (Extravehicular Activity) 23 aboard the ISS (International Space Station) on 07/16/2013 an episode of water in the EMU (Extravehicular Mobility Unit) helmet occurred, necessitating a termination of the EVA (Extravehicular Activity) shortly after it began. The root cause of the failure was determined to be ground-processing short-comings of the ALCLR (Airlock Cooling Loop Recovery) Ion Beds which led to various levels of contaminants being introduced into the Ion Beds before they left the ground. The Ion Beds were thereafter used to scrub the failed EMU cooling water loop on-orbit during routine scrubbing operations. The root cause investigation identified several areas for improvement of the ALCLR Assembly which have since been initiated. Enhanced washing techniques for the ALCLR Ion Bed have been developed and implemented. On-orbit cooling water conductivity and pH analysis capability to allow the astronauts to monitor proper operation of the ALCLR Ion Bed during scrubbing operation is being investigated. A simplified means to acquire on-orbit EMU cooling water samples has been designed. Finally, an inherently cleaner organic adsorbent to replace the current lignite-based activated carbon, and a non-separable replacement for the separable mixed ion exchange resin are undergoing evaluation. These efforts are undertaken to enhance the performance and reduce the risk associated with operations to ensure the long-term health of the EMU cooling water circuit.

  19. On the structure of solar and stellar coronae - Loops and loop heat transport

    Science.gov (United States)

    Litwin, Christof; Rosner, Robert

    1993-01-01

    We discuss the principal constraints on mechanisms for structuring and heating the outer atmospheres - the coronae - of stars. We argue that the essential cause of highly localized heating in the coronae of stars like the sun is the spatially intermittent nature of stellar surface magnetic fields, and that the spatial scale of the resulting coronal structures is related to the spatial structure of the photospheric fields. We show that significant constraints on coronal heating mechanisms derive from the observed variations in coronal emission, and, in addition, show that the observed structuring perpendicular to coronal magnetic fields imposes severe constraints on mechanisms for heat dispersal in the low-beta atmosphere. In particular, we find that most of commonly considered mechanisms for heat dispersal, such as anomalous diffusion due to plasma turbulence or magnetic field line stochasticity, are much too slow to account for the observed rapid heating of coronal loops. The most plausible mechanism appears to be reconnection at the interface between two adjacent coronal flux bundles. Based on a model invoking hyperresistivity, we show that such a mechanism naturally leads to dominance of isolated single bright coronal loops and to bright coronal plasma structures whose spatial scale transverse to the local magnetic field is comparable to observed dimensions of coronal X-ray loops.

  20. Quantum restoration of broken symmetry in one-dimensional loop ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 82; Issue 6. Quantum restoration of broken symmetry in onedimensional loop space. Pinaki Patra ... For one-dimensional loop space, a nonlinear nonlocal transformation of fields is given to make the action of the self-interacting quantum field to the free one. A specific ...

  1. Conceptional design of test loop for FIV in fuel bundle

    Energy Technology Data Exchange (ETDEWEB)

    Sim, W. G.; Yang, J. S.; Kim, S. W. [Hannam Univ., Taejeon (Korea)

    2001-01-01

    It is urgent to develop the analytical model for the structural/mechanical integrity of fuel rod. In general, it is not easy to develop a pure analytical model. Occasionally, experimental results have been utilized for the model. Because of this reason, it is required to design proper test loop. Using the optimized test loop, with the optimized test loop, the dynamic behaviour of the rod will be evaluated and the critical flow velocity, which the rod loses the stability in, will be measured for the design of the rod. To verify the integrity of the fuel rod, it is required to evaluate the dynamic behaviour and the critical flow velocity with the test loop. The test results will be utilized to the design of the rod. Generally, the rod has a ground vibration due to turbulence in wide range of flow velocity and the amplitude of vibration becomes larger by the resonance, in a range of the velocity where occurs vortex. The rod loses stability in critical flow velocity caused by fluid-elastic instability. For the purpose of the present work to perform the conceptional design of the test loop, it is necessary (1) to understand the mechanism of the flow-induced vibration and the related experimental coefficients, (2) to evaluate the existing test loops for improving the loop with design parameters and (3) to decide the design specifications of the major equipments of the loop. 35 refs., 23 figs., 2 tabs. (Author)

  2. Structure prediction of loops with fixed and flexible stems.

    Science.gov (United States)

    Subramani, A; Floudas, C A

    2012-06-14

    The prediction of loop structures is considered one of the main challenges in the protein folding problem. Regardless of the dependence of the overall algorithm on the protein data bank, the flexibility of loop regions dictates the need for special attention to their structures. In this article, we present algorithms for loop structure prediction with fixed stem and flexible stem geometry. In the flexible stem geometry problem, only the secondary structure of three stem residues on either side of the loop is known. In the fixed stem geometry problem, the structure of the three stem residues on either side of the loop is also known. Initial loop structures are generated using a probability database for the flexible stem geometry problem, and using torsion angle dynamics for the fixed stem geometry problem. Three rotamer optimization algorithms are introduced to alleviate steric clashes between the generated backbone structures and the side chain rotamers. The structures are optimized by energy minimization using an all-atom force field. The optimized structures are clustered using a traveling salesman problem-based clustering algorithm. The structures in the densest clusters are then utilized to refine dihedral angle bounds on all amino acids in the loop. The entire procedure is carried out for a number of iterations, leading to improved structure prediction and refined dihedral angle bounds. The algorithms presented in this article have been tested on 3190 loops from the PDBSelect25 data set and on targets from the recently concluded CASP9 community-wide experiment.

  3. Search for photospheric footpoints of quiet Sun transition region loops

    NARCIS (Netherlands)

    Sánchez Almeida, J.; Teriaca, L.; Sütterlin, P.; Sparado, D.; Schühle, U.; Rutten, R.J.

    2007-01-01

    Context. The footpoints of quiet Sun Transition Region (TR) loops do not seem to coincide with the photospheric magnetic structures appearing in traditional low-sensitivity magnetograms. Aims. We look for the so-far unidentified photospheric footpoints of TR loops using G-band bright points (BPs) as

  4. Rows of Dislocation Loops in Aluminium Irradiated by Aluminium Ions

    DEFF Research Database (Denmark)

    Henriksen, L.; Johansen, A.; Koch, J.

    1967-01-01

    Single-crystal aluminium specimens, irradiated with 50-keV aluminium ions, contain dislocation loops that are arranged in regular rows along <110 > directions. ©1967 The American Institute of Physics......Single-crystal aluminium specimens, irradiated with 50-keV aluminium ions, contain dislocation loops that are arranged in regular rows along directions. ©1967 The American Institute of Physics...

  5. Self-oscillating loop based piezoelectric power converter

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention relates to a piezoelectric power converter comprising an input driver electrically coupled directly to an input or primary electrode of the piezoelectric transformer without any intervening series or parallel inductor. A feedback loop is operatively coupled between an output......- oscillation loop within a zero-voltage-switching (ZVS) operation range of the piezoelectric transformer....

  6. Magnetic Field in the Gravitationally Stratified Coronal Loops

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... We study the effect of gravitational stratification on the estimation of magnetic fields in the coronal loops. By using the method of MHD seismology of kink waves for the estimation of magnetic field of coronal loops, we derive a new formula for the magnetic field considering the effect of gravitational ...

  7. Scaling properties of Wilson loops pierced by P-vortices

    DEFF Research Database (Denmark)

    Dunn, Patrick; Greensite, Jeffrey Paul

    2012-01-01

    these ratios are plotted versus loop area in physical units, for a range of lattice couplings, it is found that the points fall approximately on a single curve, consistent with scaling. We also find that the ratios are rather insensitive to the point where the minimal area of the loop is pierced by the P-vortex....

  8. Results from GRACE/SUSY at one-loop

    Indian Academy of Sciences (India)

    We report the recent development on the SUSY calculations with the help of GRACE system. GRACE/SUSY/1LOOP is the computer code which can generate Feynman diagrams in the MSSM automatically and compute one-loop amplitudes in the numerical way. We present new results of various two-body decay widths ...

  9. Operation of fixed-bed chemical looping combustion

    NARCIS (Netherlands)

    Kimball, E.; Hamers, H.P.; Cobden, P.D.; Gallucci, F.; Sint Annaland, M. van

    2013-01-01

    Chemical Looping Combustion is an alternative technology for CO2 capture. While most systems utilize dual circulating fluidized-beds, this work shows that fixed-bed Chemical Looping Combustion is a feasible configuration for this technology. The inherent separation of the CO2 from the depleted air

  10. Generalized Unitary Cuts and Integrand Reduction at Higher Loop Orders

    DEFF Research Database (Denmark)

    Frellesvig, Hjalte Axel

    a brief look at another three-loop topology, the tennis court. By the additional calculation of a number of six-propagator two-loop topologies, we illustrate two problems with our method in its four-dimensional version. The first is "the minor problem" in which a unitarity cut solutions for a topology...

  11. Theoretical study on a solar collector loop during stagnation

    DEFF Research Database (Denmark)

    Chen, Ziqian; Dragsted, Janne; Furbo, Simon

    2010-01-01

    A mathematical model simulating the stagnation behavior of a pressurized solar collector loop with solar collectors with a good emptying behavior is developed. Based on the pre-pressure of the expansion vessel, the system filling pressure of the solar collector loop and the design of the solar co...

  12. Loop-voltage tomography in tokamaks using transient synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Fisch, N.J.; Kritz, A.H. (Princeton Univ., NJ (USA). Plasma Physics Lab.; Hunter Coll., New York, NY (USA). Dept. of Physics)

    1989-07-01

    The loop voltage in tokamaks is particularly difficult to measure anywhere but at the plasma periphery. A brief, deliberate, perturbation of hot plasma electrons, however, produces a transient radiation response that is sensitive to this voltage. We investigate how such a radiation response can be used to diagnose the loop voltage. 24 refs., 6 figs.

  13. Functional Loop Dynamics of the Streptavidin-Biotin Complex

    Science.gov (United States)

    Song, Jianing; Li, Yongle; Ji, Changge; Zhang, John Z. H.

    2015-01-01

    Accelerated molecular dynamics (aMD) simulation is employed to study the functional dynamics of the flexible loop3-4 in the strong-binding streptavidin-biotin complex system. Conventional molecular (cMD) simulation is also performed for comparison. The present study reveals the following important properties of the loop dynamics: (1) The transition of loop3-4 from open to closed state is observed in 200 ns aMD simulation. (2) In the absence of biotin binding, the open-state streptavidin is more stable, which is consistent with experimental evidences. The free energy (ΔG) difference is about 5 kcal/mol between two states. But with biotin binding, the closed state is more stable due to electrostatic and hydrophobic interactions between the loop3-4 and biotin. (3) The closure of loop3-4 is concerted to the stable binding of biotin to streptavidin. When the loop3-4 is in its open-state, biotin moves out of the binding pocket, indicating that the interactions between the loop3-4 and biotin are essential in trapping biotin in the binding pocket. (4) In the tetrameric streptavidin system, the conformational change of the loop3-4 in each monomer is independent of each other. That is, there is no cooperative binding for biotin bound to the four subunits of the tetramer.

  14. Numerical evaluation of one-loop QCD amplitudes

    DEFF Research Database (Denmark)

    Badger, Simon David; Biedermann, Benedikt; Uwer, Peter

    2012-01-01

    We present the publicly available program NGluon allowing the numerical evaluation of primitive amplitudes at one-loop order in massless QCD. The program allows the computation of one-loop amplitudes for an arbitrary number of gluons. The focus of the present article is the extension to one...

  15. Control and optimization system and method for chemical looping processes

    Science.gov (United States)

    Lou, Xinsheng; Joshi, Abhinaya; Lei, Hao

    2015-02-17

    A control system for optimizing a chemical loop system includes one or more sensors for measuring one or more parameters in a chemical loop. The sensors are disposed on or in a conduit positioned in the chemical loop. The sensors generate one or more data signals representative of an amount of solids in the conduit. The control system includes a data acquisition system in communication with the sensors and a controller in communication with the data acquisition system. The data acquisition system receives the data signals and the controller generates the control signals. The controller is in communication with one or more valves positioned in the chemical loop. The valves are configured to regulate a flow of the solids through the chemical loop.

  16. Behavior of a solar collector loop during stagnation

    DEFF Research Database (Denmark)

    Chen, Ziqian; Dragsted, Janne; Furbo, Simon

    2015-01-01

    A mathematical model simulating the emptying behavior of a pressurized solar collector loop with solar collectors with a good emptying behavior is developed and validated with measured data. The calculated results are in good agreement with the measured results. The developed simulation model...... is therefore suitable to determine the behavior of a solar collector loop during stagnation. A volume ratio R, which is the ratio of the volume of the vapour in the upper pipes of the solar collector loop during stagnation and the fluid content of solar collectors, is introduced to determine the mass...... of the collector fluid pushed into the expansion vessel during stagnation, Min. A correlation function for the mass Min and the volume ratio R for solar collector loops is obtained. The function can be used to determine a suitable size of expansion vessels for solar collector loops....

  17. Finding the positive feedback loops underlying multi-stationarity

    DEFF Research Database (Denmark)

    Feliu, Elisenda; Wiuf, Carsten

    2015-01-01

    BACKGROUND: Bistability is ubiquitous in biological systems. For example, bistability is found in many reaction networks that involve the control and execution of important biological functions, such as signaling processes. Positive feedback loops, composed of species and reactions, are necessary...... for bistability, and generally for multi-stationarity, to occur. These loops are therefore often used to illustrate and pinpoint the parts of a multi-stationary network that are relevant ('responsible') for the observed multi-stationarity. However positive feedback loops are generally abundant in reaction...... networks but not all of them are important for understanding the network's dynamics. RESULTS: We present an automated procedure to determine the relevant positive feedback loops of a multi-stationary reaction network. The procedure only reports the loops that are relevant for multi-stationarity (that is...

  18. Perception as a closed-loop convergence process.

    Science.gov (United States)

    Ahissar, Ehud; Assa, Eldad

    2016-05-09

    Perception of external objects involves sensory acquisition via the relevant sensory organs. A widely-accepted assumption is that the sensory organ is the first station in a serial chain of processing circuits leading to an internal circuit in which a percept emerges. This open-loop scheme, in which the interaction between the sensory organ and the environment is not affected by its concurrent downstream neuronal processing, is strongly challenged by behavioral and anatomical data. We present here a hypothesis in which the perception of external objects is a closed-loop dynamical process encompassing loops that integrate the organism and its environment and converging towards organism-environment steady-states. We discuss the consistency of closed-loop perception (CLP) with empirical data and show that it can be synthesized in a robotic setup. Testable predictions are proposed for empirical distinction between open and closed loop schemes of perception.

  19. Concentration and length dependence of DNA looping in transcriptional regulation.

    Directory of Open Access Journals (Sweden)

    Lin Han

    2009-05-01

    Full Text Available In many cases, transcriptional regulation involves the binding of transcription factors at sites on the DNA that are not immediately adjacent to the promoter of interest. This action at a distance is often mediated by the formation of DNA loops: Binding at two or more sites on the DNA results in the formation of a loop, which can bring the transcription factor into the immediate neighborhood of the relevant promoter. These processes are important in settings ranging from the historic bacterial examples (bacterial metabolism and the lytic-lysogeny decision in bacteriophage, to the modern concept of gene regulation to regulatory processes central to pattern formation during development of multicellular organisms. Though there have been a variety of insights into the combinatorial aspects of transcriptional control, the mechanism of DNA looping as an agent of combinatorial control in both prokaryotes and eukaryotes remains unclear. We use single-molecule techniques to dissect DNA looping in the lac operon. In particular, we measure the propensity for DNA looping by the Lac repressor as a function of the concentration of repressor protein and as a function of the distance between repressor binding sites. As with earlier single-molecule studies, we find (at least two distinct looped states and demonstrate that the presence of these two states depends both upon the concentration of repressor protein and the distance between the two repressor binding sites. We find that loops form even at interoperator spacings considerably shorter than the DNA persistence length, without the intervention of any other proteins to prebend the DNA. The concentration measurements also permit us to use a simple statistical mechanical model of DNA loop formation to determine the free energy of DNA looping, or equivalently, the for looping.

  20. Autosomal mutations affecting Y chromosome loops in Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Petrucci Romano

    2008-04-01

    Full Text Available Abstract Background The Y chromosome of Drosophila melanogaster harbors several genes required for male fertility. The genes for these fertility factors are very large in size and contain conspicuous amounts of repetitive DNA and transposons. Three of these loci (ks-1, kl-3 and kl-5 have the ability to develop giant lampbrush-like loops in primary spermatocytes, a cytological manifestation of their active state in these cells. Y-loops bind a number of non-Y encoded proteins, but the mechanisms regulating their development and their specific functions are still to be elucidated. Results Here we report the results of a screen of 726 male sterile lines to identify novel autosomal genes controlling Y-loop function. We analyzed mutant testis preparations both in vivo and by immunofluorescence using antibodies directed against Y-loop-associated proteins. This screen enabled us to isolate 17 mutations at 15 loci whose wild-type function is required for proper Y-loop morphogenesis. Six of these loci are likely to specifically control loop development, while the others display pleiotropic effects on both loops and meiotic processes such as spermiogenesis, sperm development and maturation. We also determined the map position of the mutations affecting exclusively Y-loop morphology. Conclusion Our cytological screening permitted us to identify novel genetic functions required for male spermatogenesis, some of which show pleiotropic effects. Analysis of these mutations also shows that loop development can be uncoupled from meiosis progression. These data represent a useful framework for the characterization of Y-loop development at a molecular level and for the study of the genetic control of heterochromatin.

  1. Chemical Looping Combustion Reactions and Systems

    Energy Technology Data Exchange (ETDEWEB)

    Sarofim, Adel; Lighty, JoAnn; Smith, Philip; Whitty, Kevin; Eyring, Edward; Sahir, Asad; Alvarez, Milo; Hradisky, Michael; Clayton, Chris; Konya, Gabor; Baracki, Richard; Kelly, Kerry

    2014-03-01

    Chemical Looping Combustion (CLC) is one promising fuel-combustion technology, which can facilitate economic CO{sub 2} capture in coal-fired power plants. It employs the oxidation/reduction characteristics of a metal, or oxygen carrier, and its oxide, the oxidizing gas (typically air) and the fuel source may be kept separate. This topical report discusses the results of four complementary efforts: (5.1) the development of process and economic models to optimize important design considerations, such as oxygen carrier circulation rate, temperature, residence time; (5.2) the development of high-performance simulation capabilities for fluidized beds and the collection, parameter identification, and preliminary verification/uncertainty quantification; (5.3) the exploration of operating characteristics in the laboratoryscale bubbling bed reactor, with a focus on the oxygen carrier performance, including reactivity, oxygen carrying capacity, attrition resistance, resistance to deactivation, cost and availability; and (5.4) the identification of kinetic data for copper-based oxygen carriers as well as the development and analysis of supported copper oxygen carrier material. Subtask 5.1 focused on the development of kinetic expressions for the Chemical Looping with Oxygen Uncoupling (CLOU) process and validating them with reported literature data. The kinetic expressions were incorporated into a process model for determination of reactor size and oxygen carrier circulation for the CLOU process using ASPEN PLUS. An ASPEN PLUS process model was also developed using literature data for the CLC process employing an iron-based oxygen carrier, and the results of the process model have been utilized to perform a relative economic comparison. In Subtask 5.2, the investigators studied the trade-off between modeling approaches and available simulations tools. They quantified uncertainty in the high-performance computing (HPC) simulation tools for CLC bed applications. Furthermore

  2. Safe and Ecological Refluxing with a Closed-Loop Air Cooling System.

    Science.gov (United States)

    Böhmdorfer, Stefan; Eilenberger, Gottfried; Zweckmair, Thomas; Sumerskii, Ivan; Potthast, Antje; Rosenau, Thomas

    2017-01-20

    Off-the-shelf computer cooling hardware was used to construct a closed-loop air cooling system (CLACS) that is distinguished by scalability, low energy, and no tap water consumption. Constructed to be generally used with laboratory condensers, the system was tested with several common low and high boiling solvents and showed a condensation performance equivalent to conventional tap water cooling. Reaction yields were therefore unaffected. Also, long-lasting Soxhlet extractions showed no performance loss relative to conventional cooling. Optionally, the device can be assembled from low-voltage components and be powered from a battery, rendering it independent of the main power. Both investment and running costs are minimal, allowing a lab-wide adoption and elimination of the two major drawbacks of commonly employed tap water cooling: waste of drinking water and the risk of flooding. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. ETV REPORT: REMOVAL OF ARSENIC IN DRINKING WATER ORCA WATER TECHNOLOGIES KEMLOOP 1000 COAGULATION AND FILTRATION WATER TREATMENT SYSTEM

    Science.gov (United States)

    Verification testing of the ORCA Water Technologies KemLoop 1000 Coagulation and Filtration Water Treatment System for arsenic removal was conducted at the St. Louis Center located in Washtenaw County, Michigan, from March 23 through April 6, 2005. The source water was groundwate...

  4. Entropy and Free Energy of a Mobile Loop Based on the Crystal Structures of the Free and Bound Proteins

    Directory of Open Access Journals (Sweden)

    Hagai Meirovitch

    2010-08-01

    Full Text Available A mobile loop changes its conformation from “open” (free enzyme to “closed” upon ligand binding. The difference in the Helmholtz free energy, ΔFloop between these states sheds light on the mechanism of binding. With our “hypothetical scanning molecular dynamics” (HSMD-TI method ΔFloop = Ffree − Fbound where Ffree and Fbound are calculated from two MD samples of the free and bound loop states; the contribution of water is obtained by a thermodynamic integration (TI procedure. In previous work the free and bound loop structures were both attached to the same “template” which was “cut” from the crystal structure of the free protein. Our results for loop 287−290 of AcetylCholineEsterase agree with the experiment, ΔFloop~ −4 kcal/mol if the density of the TIP3P water molecules capping the loop is close to that of bulk water, i.e., Nwater = 140 − 180 waters in a sphere of a 18 Å radius. Here we calculate ΔFloop for the more realistic case, where two templates are “cut” from the crystal structures, 2dfp.pdb (bound and 2ace.pdb (free, where Nwater = 40 − 160; this requires adding a computationally more demanding (second TI procedure. While the results for Nwater ≤ 140 are computationally sound, ΔFloop is always positive (18 ± 2 kcal/mol for Nwater = 140. These (disagreeing results are attributed to the large average B-factor, 41.6 of 2dfp (23.4 Å2 for 2ace. While this conformational uncertainty is an inherent difficulty, the (unstable results for Nwater = 160 suggest that it might be alleviated by applying different (initial structural optimizations to each template.

  5. Mining protein loops using a structural alphabet and statistical exceptionality

    Directory of Open Access Journals (Sweden)

    Martin Juliette

    2010-02-01

    Full Text Available Abstract Background Protein loops encompass 50% of protein residues in available three-dimensional structures. These regions are often involved in protein functions, e.g. binding site, catalytic pocket... However, the description of protein loops with conventional tools is an uneasy task. Regular secondary structures, helices and strands, have been widely studied whereas loops, because they are highly variable in terms of sequence and structure, are difficult to analyze. Due to data sparsity, long loops have rarely been systematically studied. Results We developed a simple and accurate method that allows the description and analysis of the structures of short and long loops using structural motifs without restriction on loop length. This method is based on the structural alphabet HMM-SA. HMM-SA allows the simplification of a three-dimensional protein structure into a one-dimensional string of states, where each state is a four-residue prototype fragment, called structural letter. The difficult task of the structural grouping of huge data sets is thus easily accomplished by handling structural letter strings as in conventional protein sequence analysis. We systematically extracted all seven-residue fragments in a bank of 93000 protein loops and grouped them according to the structural-letter sequence, named structural word. This approach permits a systematic analysis of loops of all sizes since we consider the structural motifs of seven residues rather than complete loops. We focused the analysis on highly recurrent words of loops (observed more than 30 times. Our study reveals that 73% of loop-lengths are covered by only 3310 highly recurrent structural words out of 28274 observed words. These structural words have low structural variability (mean RMSd of 0.85 Å. As expected, half of these motifs display a flanking-region preference but interestingly, two thirds are shared by short (less than 12 residues and long loops. Moreover, half of

  6. Closed-loop control of zebrafish response using a bioinspired robotic-fish in a preference test.

    Science.gov (United States)

    Kopman, Vladislav; Laut, Jeffrey; Polverino, Giovanni; Porfiri, Maurizio

    2013-01-06

    In this paper, we study the response of zebrafish to a robotic-fish whose morphology and colour pattern are inspired by zebrafish. Experiments are conducted in a three-chambered instrumented water tank where a robotic-fish is juxtaposed with an empty compartment, and the preference of live subjects is scored as the mean time spent in the vicinity of the tank's two lateral sides. The tail-beating of the robotic-fish is controlled in real-time based on feedback from fish motion to explore a spectrum of closed-loop systems, including proportional and integral controllers. Closed-loop control systems are complemented by open-loop strategies, wherein the tail-beat of the robotic-fish is independent of the fish motion. The preference space and the locomotory patterns of fish for each experimental condition are analysed and compared to understand the influence of real-time closed-loop control on zebrafish response. The results of this study show that zebrafish respond differently to the pattern of tail-beating motion executed by the robotic-fish. Specifically, the preference and behaviour of zebrafish depend on whether the robotic-fish tail-beating frequency is controlled as a function of fish motion and how such closed-loop control is implemented.

  7. A Loop Current experiment: Field and remote measurements

    Science.gov (United States)

    Hamilton, Peter; Lugo-Fernández, Alexis; Sheinbaum, Julio

    2016-12-01

    An overview of a new comprehensive observational study of the Loop Current (LC) in the eastern Gulf of Mexico that encompassed full-depth and near-bottom moorings, pressure-equipped inverted echo sounders (PIES) and remote sensing is presented. The study array was designed to encompass the LC from the Campeche Bank to the west Florida escarpment. This overview centers about principal findings as they pertain to mesoscale dynamics. Two companion papers provide in-depth analyses. Three LC anticyclonic eddy separation events were observed with good 3D spatial coverage over the 2½ year extent of the field study; the three separations exhibited similar processes after the LC had extended into the eastern Gulf. Large scale (∼300 km wavelength, 40-60 day periods) southward propagating meanders developed on the eastern side of the LC over deep (∼3000 m) water that were the result of baroclinic instability between the upper layer meandering jet and lower layer cyclones and anticyclones. The lower layer was only highly energetic during relatively short (∼2-3 months) intervals just prior to or during eddy detachments because of baroclinic instability. The steepening of the meanders lead to a pinch-off of LC eddies. The deep lower-layer eddies, constrained by the closed topography of the southeastern Gulf, propagated westward across the detachment zone and appear to assist in achieving separation. Small scale (∼50-100 km, periods ∼10 days) frontal eddies, observed on the western side of the LC along the Campeche Bank slope, decay over the deep water of the northern part of an extended LC, and have little influence on lower layer eddies, the east side meanders and the eddy detachment processes.

  8. Analytical Investigation of the Heat-Transfer Limits of a Novel Solar Loop-Heat Pipe Employing a Mini-Channel Evaporator

    Directory of Open Access Journals (Sweden)

    Thierno M. O. Diallo

    2018-01-01

    Full Text Available This paper presents an analytical investigation of heat-transfer limits of a novel solar loop-heat pipe developed for space heating and domestic hot water use. In the loop-heat pipe, the condensate liquid returns to the evaporator via small specially designed holes, using a mini-channel evaporator. The study considered the commonly known heat-transfer limits of loop-heat pipes, namely, the viscous, sonic, entrainment, boiling and heat-transfer limits due to the two-phase pressure drop in the loop. The analysis considered the main factors that affect the limits in the mini-channel evaporator: the operating temperature, mini-channel aspect ratio, evaporator length, evaporator inclination angle, evaporator-to-condenser height difference and the dimension of the holes. It was found that the entrainment is the main governing limit of the system operation. With the specified loop design and operational conditions, the solar loop-heat pipe can achieve a heat-transport capacity of 725 W. The analytical model presented in this study can be used to optimise the heat-transfer capacity of the novel solar loop-heat pipe.

  9. Groundwater recharge through wells in open loop geothermal system: problems and solutions - part 1

    Directory of Open Access Journals (Sweden)

    Giovanni Pietro Beretta

    2017-07-01

    Full Text Available In the two parts of this article, the problems related to the management of water wells as part of a low-enthalpy geothermal power plant by means of heat pumps (open loop system are described. In many cases, in absence of discharge in surface water and/or to ensure the conservation of the resource from a quantitative point of view, a doublet system constituted by a pumping and a recharge well is provided. The clogging phenomenon often occurs in this kind of plant, affecting wells with different functions and different thermal potential related to water withdrawal and reinjection into the ground. This phenomenon is due to the presence of air bubbles, suspended solids, bacterial growth and to the chemical-physical reactions that are described in the text. Besides acknowledging the activities for recharge wells management to avoid the fracturing of the drain and the cementation, is also suggested the procedure of in situ tests that are used to properly determine the optimal well discharge, which determines the efficiency and effectiveness of the geothermal system and its economic performance.It is finally shown a regional regulation on the water quality used in an open loop.

  10. Tryptophan Stabilizes His-heme Loops in the Denatured State Only When It Is Near a Loop End†

    Science.gov (United States)

    Khan, Md. Khurshid A.; Miller, Abbigail L.; Bowler, Bruce E.

    2012-01-01

    We use a host-guest approach to evaluate the effect of Trp guest residues relative to Ala on the kinetics and thermodynamics of His-heme loop formation in the denatured state of iso-1-cytochrome c at 1.5, 3.0 and 6.0 M guanidine hydrochloride (GdnHCl). Trp guest residues are inserted in an alanine-rich segment placed after a unique His near the N-terminus of iso-1-cytochrome c. Trp guest residues are either four or ten residues from the His end of the 28-residue loop. We find the guest Trp stabilizes the His-heme loop at all GdnHCl concentrations when it is the 4th, but not the 10th, residue from the His end of the loop. Thus, residues near loop ends are most important in developing topological constraints in the denatured state that affect protein folding. In 1.5 M GdnHCl, loop stabilization is ~0.7 kcal/mol providing a thermodynamic rationale for the observation that Trp often mediates residual structure in the denatured state. Measurement of loop breakage rate constants, kb,His, indicates that loop stabilization by the Trp guest residues occurs completely after the transition state for loop formation in 6.0 M GdnHCl. Under poorer solvent conditions, approximately half of the stabilization of the loop has developed in the transition state, consistent with contacts in the denatured state being energetically downhill and providing evidence for funneling even near the rim of the folding funnel. PMID:22486179

  11. Chemical Looping Combustion Reactions and Systems

    Energy Technology Data Exchange (ETDEWEB)

    Sarofim, Adel; Lighty, JoAnn; Smith, Philip; Whitty, Kevin; Eyring, Edward; Sahir, Asad; Alvarez, Milo; Hradisky, Michael; Clayton, Chris; Konya, Gabor; Baracki, Richard; Kelly, Kerry

    2011-07-01

    Chemical Looping Combustion (CLC) is one promising fuel-combustion technology, which can facilitate economic CO2 capture in coal-fired power plants. It employs the oxidation/reduction characteristics of a metal, or oxygen carrier, and its oxide, the oxidizing gas (typically air) and the fuel source may be kept separate. This work focused on two classes of oxygen carrier, one that merely undergoes a change in oxidation state, such as Fe3O4/Fe2O3 and one that is converted from its higher to its lower oxidation state by the release of oxygen on heating, i.e., CuO/Cu2O. This topical report discusses the results of four complementary efforts: (1) the development of process and economic models to optimize important design considerations, such as oxygen carrier circulation rate, temperature, residence time; (2) the development of high-performance simulation capabilities for fluidized beds and the collection, parameter identification, and preliminary verification/uncertainty quantification (3) the exploration of operating characteristics in the laboratory-scale bubbling bed reactor, with a focus on the oxygen carrier performance, including reactivity, oxygen carrying capacity, attrition resistance, resistance to deactivation, cost and availability (4) the identification of mechanisms and rates for the copper, cuprous oxide, and cupric oxide system using thermogravimetric analysis.

  12. Gauge and integrable theories in loop spaces

    Science.gov (United States)

    Ferreira, L. A.; Luchini, G.

    2012-05-01

    We propose an integral formulation of the equations of motion of a large class of field theories which leads in a quite natural and direct way to the construction of conservation laws. The approach is based on generalized non-abelian Stokes theorems for p-form connections, and its appropriate mathematical language is that of loop spaces. The equations of motion are written as the equality of a hyper-volume ordered integral to a hyper-surface ordered integral on the border of that hyper-volume. The approach applies to integrable field theories in (1+1) dimensions, Chern-Simons theories in (2+1) dimensions, and non-abelian gauge theories in (2+1) and (3+1) dimensions. The results presented in this paper are relevant for the understanding of global properties of those theories. As a special byproduct we solve a long standing problem in (3+1)-dimensional Yang-Mills theory, namely the construction of conserved charges, valid for any solution, which are invariant under arbitrary gauge transformations.

  13. Laser Metrology Heterodyne Phase-Locked Loop

    Science.gov (United States)

    Loya, Frank; Halverson, Peter

    2009-01-01

    A method reduces sensitivity to noise in a signal from a laser heterodyne interferometer. The phase-locked loop (PLL) removes glitches that occur in a zero-crossing detector s output [that can happen if the signal-to-noise ratio (SNR) of the heterodyne signal is low] by the use of an internal oscillator that produces a square-wave signal at a frequency that is inherently close to the heterodyne frequency. It also contains phase-locking circuits that lock the phase of the oscillator to the output of the zero-crossing detector. Because the PLL output is an oscillator signal, it is glitch-free. This enables the ability to make accurate phase measurements in spite of low SNR, creates an immunity to phase error caused by shifts in the heterodyne frequency (i.e. if the target moves causing Doppler shift), and maintains a valid phase even when the signal drops out for brief periods of time, such as when the laser is blocked by a stray object.

  14. Two integrator loop quadrature oscillators: A review

    Directory of Open Access Journals (Sweden)

    Ahmed M. Soliman

    2013-01-01

    Full Text Available A review of the two integrator loop oscillator circuits providing two quadrature sinusoidal output voltages is given. All the circuits considered employ the minimum number of capacitors namely two except one circuit which uses three capacitors. The circuits considered are classified to four different classes. The first class includes floating capacitors and floating resistors and the active building blocks realizing these circuits are the Op Amp or the OTRA. The second class employs grounded capacitors and includes floating resistors and the active building blocks realizing these circuits are the DCVC or the unity gain cells or the CFOA. The third class employs grounded capacitors and grounded resistors and the active building blocks realizing these circuits are the CCII. The fourth class employs grounded capacitors and no resistors and the active building blocks realizing these circuits are the TA. Transformation methods showing the generation of different classes from each other is given in details and this is one of the main objectives of this paper.

  15. Timing Jitter Analysis for Clock recovery Circuits Based on an Optoelectronic Phase-Locked Loop (OPLL)

    DEFF Research Database (Denmark)

    Zibar, Darko; Mørk, Jesper; Oxenløwe, Leif Katsuo

    2005-01-01

    Timing jitter of an OPLL based clock recovery is investigated. We demonstrate how loop gain, input and VCO signal jitter, loop filter bandwidth and a loop time delay influence jitter of the extracted clock signal...

  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. A Generalized Theory of DNA Looping and Cyclization

    Science.gov (United States)

    Wilson, David; Lillian, Todd; Perkins, Noel; Tkachenko, Alexei; Meiners, Jens-Christian

    2010-03-01

    We have developed a semi-analytic method for calculating the Stockmayer Jacobson J-factor for protein mediated DNA loops. The formation of DNA loops on the order of a few persistence lengths is a key component in many biological regulatory functions. The binding of LacI protein within the Lac Operon of E.coli serves as the canonical example for loop regulated transcription. We use a non-linear rod model to determine the equilibrium shape of the inter-operator DNA loop under prescribed binding constraints while taking sequence-dependent curvature and elasticity into account. Then we construct a Hamiltonian that describes thermal fluctuations about the open and looped equilibrium states, yielding the entropic and enthalpic costs of loop formation. Our work demonstrates that even for short sequences of the order one persistence length, entropic terms contribute substantially to the J factor. We also show that entropic considerations are able to determine the most favorable binding topology. The J factor can be used to compare the relative loop lifetimes of various DNA sequences, making it a useful tool in sequence design. A corollary of this work is the computation of an effective torsional persistence length, which demonstrates how torsion bending coupling in a constrained geometry affects the conversion of writhe to twist.

  18. The Role of Entropic Effects on DNA Loop Formation

    Science.gov (United States)

    Wilson, David; Tkachenko, Alexei; Lillian, Todd; Perkins, Noel; Meiners, Jens Christian

    2009-03-01

    The formation of protein mediated DNA loops often regulates gene expression. Typically, a protein is simultaneously bound to two DNA operator sites. An example is the lactose repressor which binds to the Lac operon of E. coli. We characterize the mechanics of this system by calculating the free energy cost of loop formation. We construct a Hamiltonian that describes the change in DNA bending energy due to linear perturbations about the looped and open states, starting from a non-linear mechanical rod model that determines the shape and bending energy of the inter-operator DNA loop while capturing the intrinsic curvature and sequence-dependent elasticity of the DNA. The crystal structure of the LacI protein provides the boundary conditions for the DNA. We then calculate normal modes of the open and closed loops to account for the thermal fluctuations. The ratio of determinants of the two Hamiltonians yields the partition function, and the enthalphic and entropic cost of looping. This calculation goes beyond standard elastic energy models because it fully accounts for the substantial entropic differences between the two states. It also includes effects of sequence dependent curvature and stiffness and allows anisotropic variations in persistence length. From the free energy we then calculate the J-factor and ratio of loop lifetimes.

  19. Two-Loop Scattering Amplitudes from the Riemann Sphere

    CERN Document Server

    Geyer, Yvonne; Monteiro, Ricardo; Tourkine, Piotr

    2016-01-01

    The scattering equations give striking formulae for massless scattering amplitudes at tree level and, as shown recently, at one loop. The progress at loop level was based on ambitwistor string theory, which naturally yields the scattering equations. We proposed that, for ambitwistor strings, the standard loop expansion in terms of the genus of the worldsheet is equivalent to an expansion in terms of nodes of a Riemann sphere, with the nodes carrying the loop momenta. In this paper, we show how to obtain two-loop scattering equations with the correct factorization properties. We adapt genus-two integrands from the ambitwistor string to the nodal Riemann sphere and show that these yield correct answers, by matching standard results for the four-point two-loop amplitudes of maximal supergravity and super-Yang-Mills theory. In the Yang-Mills case, this requires the loop analogue of the Parke-Taylor factor carrying the colour dependence, which includes non-planar contributions.

  20. Loop equations and bootstrap methods in the lattice

    Science.gov (United States)

    Anderson, Peter D.; Kruczenski, Martin

    2017-08-01

    Pure gauge theories can be formulated in terms of Wilson Loops by means of the loop equation. In the large-N limit this equation closes in the expectation value of single loops. In particular, using the lattice as a regulator, it becomes a well defined equation for a discrete set of loops. In this paper we study different numerical approaches to solving this equation. Previous ideas gave good results in the strong coupling region. Here we propose an alternative method based on the observation that certain matrices ρ ˆ of Wilson loop expectation values are positive definite. They also have unit trace (ρ ˆ ⪰ 0 ,Tr ρ ˆ = 1), in fact they can be defined as reduced density matrices in the space of open loops after tracing over color indices and can be used to define an entropy associated with the loss of information due to such trace SWL = -Tr [ ρ ˆ ln ⁡ ρ ˆ ]. The condition that such matrices are positive definite allows us to study the weak coupling region which is relevant for the continuum limit. In the exactly solvable case of two dimensions this approach gives very good results by considering just a few loops. In four dimensions it gives good results in the weak coupling region and therefore is complementary to the strong coupling expansion. We compare the results with standard Monte Carlo simulations.

  1. Development of a closed and open loop solar tracker technology

    Directory of Open Access Journals (Sweden)

    Aurélio Gouvêa Melo

    2017-05-01

    Full Text Available Solar energy is among the renewable energy sources that received greater addition in installed capacity. However, it accounts for a small fraction of the energy matrix of most countries. Electric energy generation by solar systems can be improved through tracking. This work aimed to develop and compare a closed and an open loop solar tracking system. The closed loop system was developed using Light Dependent Resistors. An algorithm was developed for the open loop tracker as a function of the geometric relation between the sun and the photovoltaic module. A simulation was run to compare this algorithm with a system using tracking at fixed time intervals, for clear sky conditions, with different tracking parameters and for five different latitudes. No significant difference was observed between the proposed open loop tracking algorithm and the fixed time interval algorithm for the tracking parameters evaluated. The open and closed loop solar tracking systems were compared experimentally in Rio das Ostras, Brazil (22.49 °S 41.92° W. An average gain of 28.5% was observed for the open loop tracking system over a latitude tilted system and 33.0% for the closed loop tracking system.

  2. The free-energy cost of interaction between DNA loops.

    Science.gov (United States)

    Huang, Lifang; Liu, Peijiang; Yuan, Zhanjiang; Zhou, Tianshou; Yu, Jianshe

    2017-10-03

    From the viewpoint of thermodynamics, the formation of DNA loops and the interaction between them, which are all non-equilibrium processes, result in the change of free energy, affecting gene expression and further cell-to-cell variability as observed experimentally. However, how these processes dissipate free energy remains largely unclear. Here, by analyzing a mechanic model that maps three fundamental topologies of two interacting DNA loops into a 4-state model of gene transcription, we first show that a longer DNA loop needs more mean free energy consumption. Then, independent of the type of interacting two DNA loops (nested, side-by-side or alternating), the promotion between them always consumes less mean free energy whereas the suppression dissipates more mean free energy. More interestingly, we find that in contrast to the mechanism of direct looping between promoter and enhancer, the facilitated-tracking mechanism dissipates less mean free energy but enhances the mean mRNA expression, justifying the facilitated-tracking hypothesis, a long-standing debate in biology. Based on minimal energy principle, we thus speculate that organisms would utilize the mechanisms of loop-loop promotion and facilitated tracking to survive in complex environments. Our studies provide insights into the understanding of gene expression regulation mechanism from the view of energy consumption.

  3. Intraglomerular microcirculation: measurements of single glomerular loop flow in rats.

    Science.gov (United States)

    Steinhausen, M; Zimmerhackl, B; Thederan, H; Dussel, R; Parekh, N; Esslinger, H U; von Hagens, G; Komitowski, D; Dallenbach, F D

    1981-08-01

    With the use of a new fluorescent microscopic technique, we were able to measure the mean intracapillary velocities and pressures of single capillary loops of renal glomeruli of living rats. The technique involved photographing and recording the flow of fluorescent latex particles through the glomerular loops with a television monitor. In 25 rats the single glomerular loop flow velocity was 781 +/- (SD) 271 micrometers . sec-1. The mean diameter of the capillary loops measured 8.4 +/- 1.4 micrometers; their lengths were 72.3 +/- 37.5 micrometers. From the decrease in velocity of flow along the capillary loop, we were able to evaluate the filtration equivalent for the capillary surface. It was possible to measure intracapillary pressures of single glomerular loops continuously under microscopic control. High intracapillary pressures correlated with high intracapillary velocities. From the data we obtained, we were unable to calculate a filtration equilibrium at the ends of the observed capillary loops. For further correlations, we injected the glomeruli we had studied in the living state and examined them with the scanning electron microscope.

  4. Mechanical evaluation of space closure loops in Orthodontics

    Directory of Open Access Journals (Sweden)

    Eduardo Uggeri Rodrigues

    2011-02-01

    Full Text Available This study evaluated the mechanical performance of teardrop-shaped loops and teardrop-shaped loops with helix used in orthodontic space closure. Sixty retraction loops made with 0.019" x 0.025" stainless steel (SS and beta-titanium (BT wires were used. They were attached to a testing machine to measure the magnitudes of the sagittal force and the load-deflection ratio necessary for 1 mm, 2 mm and 3 mm activation. The results demonstrated that the BT alloy presented significantly smaller mean values (p < 0.01 of sagittal force and load-deflection than the SS alloy. The loop with the highest mean value of sagittal force and load-deflection was the teardrop-shaped loop (p < 0.01. Differences were observed in the mean values of sagittal force and load-deflection among activations, and the highest mean value was found in the activation of 3 mm, while the smallest mean value was evident in the activation of 1 mm (p < 0.01. It could be concluded that the metallic alloy used and the presence of a helix in configuration of the loops may have a strong influence on the sagittal force produced and on the load-deflection ratio; the teardrop-shaped loops and teardrop-shaped loops with helix in BT presented the release of lighter forces; the teardrop-shaped loop in SS generated a high load-deflection ratio, providing high magnitudes of horizontal force during its deactivation.

  5. Subscriber loop optical distribution architecture: a cost-effective TDM/TDMA subscriber loop system

    Science.gov (United States)

    Rueda, Javier; Eldering, Charles A.

    1992-02-01

    While it is clear that the development of the laser and low loss optical fiber has had an unmistakable impact on the field of telecommunications, the deployment of optical fiber in the subscriber (local) loop is an especially challenging task. It requires development of low cost equipment that will initially be used at low bit rates (Transmission of TV data, in either analog or digital form, will make more efficient use of the fiber bandwidth and generate additional revenues. But as seen from the perspective of the telephony industry, basic telephone services are the principal source of revenue and economic justification for the installation of subscriber loop fiber systems. For large scale deployment in the subscriber loop, the fiber optic system must provide basic telephone services with equal or better performance at a cost that is competitive with that of existing copper pair technology. In this paper we examine a number of possible fiber-to-the-home (FTTH) and fiber-to-the-curb (FTTC) architectures, and present an architecture for urban areas that is best classified as fiber-to-the-building (FTTB). We examine the costs and performance characteristics of the various networks. We show how demographic information can be used to optimize the capacity of the remote terminals. It is shown that for the demography of Spain (where in urban areas the majority of the population resides in apartment buildings with 10 or more dwellings) a remote terminal with a variable subscriber capacity presents a cost savings over remote terminals with a fixed number of subscriber channels.

  6. Fiber-bragg grating-loop ringdown method and apparatus

    Science.gov (United States)

    Wang, Chuji [Starkville, MS

    2008-01-29

    A device comprising a fiber grating loop ringdown (FGLRD) system of analysis is disclosed. A fiber Bragg grating (FBG) or Long-Period grating (LPG) written in a section of single mode fused silica fiber is incorporated into a fiber loop. By utilizing the wing areas of the gratings' bandwidth as a wavelength dependent attenuator of the light transmission, a fiber grating loop ringdown concept is formed. One aspect of the present invention is temperature sensing, which has been demonstrated using the disclosed device. Temperature measurements in the areas of accuracy, stability, high temperature, and dynamic range are also described.

  7. A method for closed loop automatic tuning of PID controllers

    Directory of Open Access Journals (Sweden)

    Tor S. Schei

    1992-07-01

    Full Text Available A simple method for the automatic tuning of PID controllers in closed loop is proposed. A limit cycle is generated through a nonlinear feedback path from the process output to the controller reference signal. The frequency of this oscillation is above the crossover frequency and below the critical frequency of the loop transfer function. The amplitude and frequency of the oscillation are estimated and the control parameters are adjusted iteratively such that the closed loop transfer function from the controller reference to the process output attains a specified amplitude at the oscillation frequency.

  8. Multifrequency zero-jitter delay-locked loop

    Science.gov (United States)

    Efendovich, Avner; Afek, Yachin; Sella, Coby; Bikowsky, Zeev

    1994-01-01

    The approach of an all-digital phase locked loop is used in this delay-locked loop circuit. This design is designated to a system with two processing units, a master CPU and a slave system chip, that share the same bus. It allows maximum utilization of the bus, as the minimal skew between the clocks of the two components significantly reduces idle periods, and also set-up and hold times. Changes in the operating frequency are possible, without falling out of synchronization. Due to the special lead-lag phase detector, the jitter of the clock is zero, when the loop is locked, under any working conditions.

  9. A simple gastropexy for the loop-gastrostomy tube

    Directory of Open Access Journals (Sweden)

    Pang Ah-San

    2012-01-01

    Full Text Available The percutaneous endoscopic gastrostomy has been in clinical use for more than three decades. A recent innovation, the loop-gastrostomy, is more suitable for developing countries because the tube cannot be dislodged and is easy to change. Gastropexy and gastrostomy are separate but related moieties. We describe a novel technique to add a gastropexy to the loop-gastrostomy, using it successfully in a man with permanent dysphagia. It involved creating a secondary loop at the mid-portion of the LOOPPEG® 3G tube with absorbable ligatures.

  10. Numerical implementation of the loop-tree duality method

    Energy Technology Data Exchange (ETDEWEB)

    Buchta, Sebastian; Rodrigo, German [Universitat de Valencia-Consejo Superior de Investigaciones Cientificas, Parc Cientific, Instituto de Fisica Corpuscular, Valencia (Spain); Chachamis, Grigorios [Universidad Autonoma de Madrid, Instituto de Fisica Teorica UAM/CSIC, Madrid (Spain); Draggiotis, Petros [Institute of Nuclear and Particle Physics, NCSR ' ' Demokritos' ' , Agia Paraskevi (Greece)

    2017-05-15

    We present a first numerical implementation of the loop-tree duality (LTD) method for the direct numerical computation of multi-leg one-loop Feynman integrals. We discuss in detail the singular structure of the dual integrands and define a suitable contour deformation in the loop three-momentum space to carry out the numerical integration. Then we apply the LTD method to the computation of ultraviolet and infrared finite integrals, and we present explicit results for scalar and tensor integrals with up to eight external legs (octagons). The LTD method features an excellent performance independently of the number of external legs. (orig.)

  11. Protein Loop Closure Using Orientational Restraints from NMR Data

    Science.gov (United States)

    Tripathy, Chittaranjan; Zeng, Jianyang; Zhou, Pei; Donald, Bruce Randall

    Protein loops often play important roles in biological functions such as binding, recognition, catalytic activities and allosteric regulation. Modeling loops that are biophysically sensible is crucial to determining the functional specificity of a protein. A variety of algorithms ranging from robotics-inspired inverse kinematics methods to fragmentbased homology modeling techniques have been developed to predict protein loops. However, determining the 3D structures of loops using global orientational restraints on internuclear vectors, such as those obtained from residual dipolar coupling (RDC) data in solution Nuclear Magnetic Resonance (NMR) spectroscopy, has not been well studied. In this paper, we present a novel algorithm that determines the protein loop conformations using a minimal amount of RDC data. Our algorithm exploits the interplay between the sphero-conics derived from RDCs and the protein kinematics, and formulates the loop structure determination problem as a system of low-degree polynomial equations that can be solved exactly and in closed form. The roots of these polynomial equations, which encode the candidate conformations, are searched systematically, using efficient and provable pruning strategies that triage the vast majority of conformations, to enumerate or prune all possible loop conformations consistent with the data. Our algorithm guarantees completeness by ensuring that a possible loop conformation consistent with the data is never missed. This data-driven algorithm provides a way to assess the structural quality from experimental data with minimal modeling assumptions. We applied our algorithm to compute the loops of human ubiquitin, the FF Domain 2 of human transcription elongation factor CA150 (FF2), the DNA damage inducible protein I (DinI) and the third IgG-binding domain of Protein G (GB3) from experimental RDC data. A comparison of our results versus those obtained by using traditional structure determination protocols on the

  12. Isothermal and Multithermal Analysis of Coronal Loops Observed with Atmospheric Imaging Assembly. II. 211 Å Selected Loops

    Science.gov (United States)

    Schmelz, J. T.; Worley, B. T.; Anderson, D. J.; Pathak, S.; Kimble, J. A.; Jenkins, B. S.; Saar, S. H.

    2011-09-01

    An important component of coronal loop analysis involves conflicting results on the cross-field temperature distribution. Are loops isothermal or multithermal? The Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory was designed in part to answer this question. AIA has a series of coronal filters that peak at different temperatures and cover the entire active region temperature range. These properties should make AIA ideal for multithermal analysis, but recent results have shown that the response functions of two of the filters, AIA 94 and 131 Å, are missing a significant number of low-temperature emission lines. Here we analyze coronal loops from several active regions that were chosen in the 211 Å channel of AIA, which has a peak response temperature of log T = 6.3. The differential emission measure (DEM) analysis of the 12 loops in our sample reveals that using data from the 131 Å AIA filter distorts the results, and we have no choice but to do the analysis without these data. The 94 Å data do not appear to be as important, simply because the chosen loops are not visible in this channel. If we eliminate the 131 Å data, however, we find that our DEM analysis is not well constrained on the cool temperature end of six of our loops. The information revealed by our 211 selected loops indicates that additional atomic data are required in order to pin down the cross-field temperature distribution.

  13. DNA looping by FokI: the impact of twisting and bending rigidity on protein-induced looping dynamics

    Science.gov (United States)

    Laurens, Niels; Rusling, David A.; Pernstich, Christian; Brouwer, Ineke; Halford, Stephen E.; Wuite, Gijs J. L.

    2012-01-01

    Protein-induced DNA looping is crucial for many genetic processes such as transcription, gene regulation and DNA replication. Here, we use tethered-particle motion to examine the impact of DNA bending and twisting rigidity on loop capture and release, using the restriction endonuclease FokI as a test system. To cleave DNA efficiently, FokI bridges two copies of an asymmetric sequence, invariably aligning the sites in parallel. On account of the fixed alignment, the topology of the DNA loop is set by the orientation of the sites along the DNA. We show that both the separation of the FokI sites and their orientation, altering, respectively, the twisting and the bending of the DNA needed to juxtapose the sites, have profound effects on the dynamics of the looping interaction. Surprisingly, the presence of a nick within the loop does not affect the observed rigidity of the DNA. In contrast, the introduction of a 4-nt gap fully relaxes all of the torque present in the system but does not necessarily enhance loop stability. FokI therefore employs torque to stabilise its DNA-looping interaction by acting as a ‘torsional’ catch bond. PMID:22373924

  14. Ground experimental investigations into an ejected spray cooling system for space closed-loop application

    Directory of Open Access Journals (Sweden)

    Zhang Hongsheng

    2016-06-01

    Full Text Available Spray cooling has proved its superior heat transfer performance in removing high heat flux for ground applications. However, the dissipation of vapor–liquid mixture from the heat surface and the closed-loop circulation of the coolant are two challenges in reduced or zero gravity space environments. In this paper, an ejected spray cooling system for space closed-loop application was proposed and the negative pressure in the ejected condenser chamber was applied to sucking the two-phase mixture from the spray chamber. Its ground experimental setup was built and experimental investigations on the smooth circle heat surface with a diameter of 5 mm were conducted with distilled water as the coolant spraying from a nozzle of 0.51 mm orifice diameter at the inlet temperatures of 69.2 °C and 78.2 °C under the conditions of heat flux ranging from 69.76 W/cm2 to 311.45 W/cm2, volume flow through the spray nozzle varying from 11.22 L/h to 15.76 L/h. Work performance of the spray nozzle and heat transfer performance of the spray cooling system were analyzed; results show that this ejected spray cooling system has a good heat transfer performance and provides valid foundation for space closed-loop application in the near future.

  15. Diuretics in the treatment of hypertension. Part 2: loop diuretics and potassium-sparing agents.

    Science.gov (United States)

    Tamargo, Juan; Segura, Julian; Ruilope, Luis M

    2014-04-01

    Diuretics enhance the renal excretion of Na(+) and water due to a direct action at different tubular sites of the nephron where solute re-absorption occurs. This paper focuses on the mechanism of action, pharmacodynamics, antihypertensive effects, adverse effects, interactions and contraindications of loop diuretics and potassium-sparing agents (including mineralocorticoid receptor antagonists (MRAs) and epithelial Na(+) channel blockers). Loop diuretics are less effective than thiazide diuretics in lowering blood pressure, so that their major use is in edematous patients with congestive heart failure (HF), cirrhosis with ascites and nephritic edema. MRAs represent a major advance in the treatment of resistant hypertension, primary and secondary hyperaldosteronism and in patients with systolic HF to reduce the risks of hospitalization and of premature death. Potassium-sparing diuretics when coadministered with diuretics (thiazides and loop diuretics) working at more proximal nephron locations reduce the risk of hypokalemia and hypomagnesemia and the risk of cardiac arrhythmias. At the end of the article, the basis for the combination of diuretics with other antihypertensive drugs to achieve blood pressure targets is presented.

  16. Metabolism of hydroxy fatty acids in dogs with steatorrhea secondary to experimentally produced intestinal blind loops.

    Science.gov (United States)

    Kim, Y S; Spritz, N

    1968-07-01

    Several aspects of the metabolism of hydroxy fatty acids were studied in dogs with steatorrhea resulting from an experimentally produced jejunal blind loop. In these animals hydroxy acids were present in the stool in amounts far above normal. These acids disappeared from the feces during tetracycline administration and after exclusion of the blind loop-both procedures that corrected the steatorrhea apparently by reducing bacterial overgrowth. Hydroxy acids persisted in higher than normal amounts, however, after administration of taurocholic acid, which also corrected the steatorrhea, but by a different mechanism. Both in normal dogs and in those with blind loops, hydroxy acid constituted a higher percentage of total fatty acids in the jejunum. A possible conclusion is that hydroxy fatty acids have an enterohepatic circulation via the portal system. When hydroxy acids were fed to normal dogs, steatorrhea was not produced and absorption in amounts similar to that of unsubstituted stearic acid was observed. Isotopic oleic and linoleic acids were converted to hydroxy acids both in vivo and during in vitro incubation with feces; stearic acid was not. These findings support the idea that hydroxy acids arise by the addition of water across double bonds, this addition being catalyzed by enzymes of intestinal bacteria.

  17. Simulation of Hybrid Photovoltaic Solar Assisted Loop Heat Pipe/Heat Pump System

    Directory of Open Access Journals (Sweden)

    Nannan Dai

    2017-02-01

    Full Text Available A hybrid photovoltaic solar assisted loop heat pipe/heat pump (PV-SALHP/HP water heater system has been developed and numerically studied. The system is the combination of loop heat pipe (LHP mode and heat pump (HP mode, and the two modes can be run separately or compositely according to the weather conditions. The performances of independent heat pump (HP mode and hybrid loop heat pipe/heat pump (LHP/HP mode were simulated and compared. Simulation results showed that on typical sunny days in spring or autumn, using LHP/HP mode could save 40.6% power consumption than HP mode. In addition, the optimal switchover from LHP mode to HP mode was analyzed in different weather conditions for energy saving and the all-year round operating performances of the system were also simulated. The simulation results showed that hybrid LHP/HP mode should be utilized to save electricity on sunny days from March to November and the system can rely on LHP mode alone without any power consumption in July and August. When solar radiation and ambient temperature are low in winter, HP mode should be used

  18. Seismology of Transversely Oscillating Coronal Loops with Siphon Flows

    Science.gov (United States)

    Terradas, J.; Arregui, I.; Verth, G.; Goossens, M.

    2011-03-01

    There are ubiquitous flows observed in the solar atmosphere of sub-Alfvénic speeds; however, after flaring and coronal mass ejection events flows can become Alfvénic. In this Letter, we derive an expression for the standing kink mode frequency due to siphon flow in coronal loops, valid for both low and high speed regimes. It is found that siphon flow introduces a linear, spatially dependent phase shift along coronal loops and asymmetric eigenfunctions. We demonstrate how this theory can be used to determine the kink and flow speed of oscillating coronal loops with reference to an observational case study. It is shown that the presence of siphon flow can cause the underestimation of magnetic field strength in coronal loops using the traditional seismological methods.

  19. Vapor Compressor Driven Hybrid Two-Phase Loop Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Phase I project successfully demonstrated the feasibility of the vapor compression hybrid two-phase loop (VCHTPL). The test results showed the high...

  20. A Culture-Behavior-Brain Loop Model of Human Development.

    Science.gov (United States)

    Han, Shihui; Ma, Yina

    2015-11-01

    Increasing evidence suggests that cultural influences on brain activity are associated with multiple cognitive and affective processes. These findings prompt an integrative framework to account for dynamic interactions between culture, behavior, and the brain. We put forward a culture-behavior-brain (CBB) loop model of human development that proposes that culture shapes the brain by contextualizing behavior, and the brain fits and modifies culture via behavioral influences. Genes provide a fundamental basis for, and interact with, the CBB loop at both individual and population levels. The CBB loop model advances our understanding of the dynamic relationships between culture, behavior, and the brain, which are crucial for human phylogeny and ontogeny. Future brain changes due to cultural influences are discussed based on the CBB loop model. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. The Open-Loop Linear Quadratic Differential Game Revisited

    NARCIS (Netherlands)

    Engwerda, J.C.

    2005-01-01

    In this note we reconsider the indefinite open-loop Nash linear quadratic differential game with an infinite planning horizon.In particular we derive both necessary and sufficient conditions under which the game will have a unique equilibrium.

  2. Nonlinear model predictive control for chemical looping process

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Abhinaya; Lei, Hao; Lou, Xinsheng

    2017-08-22

    A control system for optimizing a chemical looping ("CL") plant includes a reduced order mathematical model ("ROM") that is designed by eliminating mathematical terms that have minimal effect on the outcome. A non-linear optimizer provides various inputs to the ROM and monitors the outputs to determine the optimum inputs that are then provided to the CL plant. An estimator estimates the values of various internal state variables of the CL plant. The system has one structure adapted to control a CL plant that only provides pressure measurements in the CL loops A and B, a second structure adapted to a CL plant that provides pressure measurements and solid levels in both loops A, and B, and a third structure adapted to control a CL plant that provides full information on internal state variables. A final structure provides a neural network NMPC controller to control operation of loops A and B.

  3. Supernova 1987 A - The nebular loops and 'Napoleon's Hat'

    Science.gov (United States)

    Wang, L.; Wampler, E. J.

    1992-08-01

    We discuss observations of the circumstellar environment of SN 1987A that were obtained between August 1989 and January 1992 at ESO's New Technology Telescope. We find that the angular dimensions of the two nebular loops (Wampler et al., 1990) have not changed during this period. Therefore these loops are confined to a small region. The expansion velocity of the loops is less than about 40 km/s if the loops expanded with a uniform velocity from a common origin. This structure and velocity is hard to reproduce with existing wind interaction models. Our observations further suggest that the Napoleon's Hat nebula does not originate from the general background LMC dust, but from a bow shock dust whose origins are closely related to the stellar winds from the progenitor star of SN 1987A.

  4. N >= 4 Supergravity Amplitudes from Gauge Theory at Two Loops

    Energy Technology Data Exchange (ETDEWEB)

    Boucher-Veronneau, C.; Dixon, L.J.; /SLAC

    2012-02-15

    We present the full two-loop four-graviton amplitudes in N = 4, 5, 6 supergravity. These results were obtained using the double-copy structure of gravity, which follows from the recently conjectured color-kinematics duality in gauge theory. The two-loop four-gluon scattering amplitudes in N = 0, 1, 2 supersymmetric gauge theory are a second essential ingredient. The gravity amplitudes have the expected infrared behavior: the two-loop divergences are given in terms of the squares of the corresponding one-loop amplitudes. The finite remainders are presented in a compact form. The finite remainder for N = 8 supergravity is also presented, in a form that utilizes a pure function with a very simple symbol.

  5. Tiny Open-Loop Atmospheric Sensing Technique Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The TOAST instrument is an open-loop processor of GPS navigation signals. The electronics fits on a single 10 cm square card with RF components and digital...

  6. Heating-related flows in cool solar loops

    Science.gov (United States)

    Klimchuk, J. A.; Mariska, J. T.

    1988-01-01

    The effects of spatial and temporal variations in the heating of cool loop models are investigated in an attempt to explain the net redshifts that are observed on the sun. The response of initially static cool loops to changes in the energy input is simulated. For hot loops, it is found that spatially asymmetric changes produce a final steady state that is dynamic, and that spatially symmetric changes produce a final state that is static. Some general properties of cool loop equilibria are discussed, emphasizing the relationship between structure and energy input. The results are unable to explain the net redshifts observed in emission lines formed near 100,000 K on the sun.

  7. Diffeomorphism invariant cosmological sector in loop quantum gravity

    Science.gov (United States)

    Beetle, C.; Engle, J. S.; Hogan, M. E.; Mendonça, P.

    2017-11-01

    In this paper we work out in detail a new proposal to define rigorously a sector of loop quantum gravity at the diffeomorphism invariant level corresponding to homogeneous and isotropic cosmologies, and propose how to compare in detail the physics of this sector with that of loop quantum cosmology. The key technical steps we have completed are (a) to formulate conditions for homogeneity and isotropy in a diffeomorphism covariant way on the classical phase space of general relativity, and (b) to translate these conditions consistently using well-understood techniques to loop quantum gravity. To impose the symmetry at the quantum level, on both the connection and its conjugate momentum, the method used necessarily has similiarities to the Gupta-Bleuler method of quantizing the electromagnetic field. Lastly, a strategy for embedding states of loop quantum cosmology into this new homogeneous isotropic sector, and using this embedding to compare the physics, is presented.

  8. Formation and Properties of Molecular Loops at Polymeric Interfaces

    Science.gov (United States)

    Rice, J. Kevin

    2005-03-01

    In this study, we investigate the formation, kinetics, and resultant strength improvements of multiply bound polymer loops at multicomponent polymeric interfaces. We have first studied a model system consisting of a silicon substrate, an epoxy terminated monolayer, and dicarboxy terminated polystyrene to characterize the formation of the surface bound molecular loops. Interfacial strength improvement via loop formation in this model system has also been investigated using asymmetric double cantilever beam (ADCB) analysis. Further, the kinetics of loop formation at a soft interface between polystyrene and poly(methyl methacrylate) has been investigated with neutron reflectivity. This data will then be used to apply the technique to a range of real systems, such as layered-silicate or carbon nanotube filled polymeric systems, with the goal of improving dispersion and desired property enhancement within these systems.

  9. The modified Altemeier procedure for a loop colostomy prolapse.

    Science.gov (United States)

    Watanabe, Makoto; Murakami, Masahiko; Ozawa, Yoshiaki; Uchida, Marie; Yamazaki, Kimiyasu; Fujimori, Akira; Otsuka, Koji; Aoki, Takeshi

    2015-11-01

    Loop colostomy prolapse is associated with an impaired quality of life. Surgical treatment may sometimes be required for cases that cannot be closed by colon colostomy because of high-risk morbidities or advanced disease. We applied the Altimeter operation for patients with transverse loop colostomy. The Altemeier operation is therefore indicated for rectal prolapse. This technique involves a simple operation, which includes a circumferential incision through the full thickness of the outer and inner cylinder of the prolapsed limb, without incising the abdominal wall, and anastomosis with sutures using absorbable thread. We performed the Altemeier operation for three cases of loop stomal prolapse. Those patients demonstrated no postoperative complications (including obstruction, prolapse recurrence, or hernia). Our findings suggest that this procedure is useful as an optional surgical treatment for cases of transverse loop colostomy prolapse as a permanent measure in patients with high-risk morbidities or advanced disease.

  10. Closed Loop Supply Chains for Sustainable Mass Customization

    DEFF Research Database (Denmark)

    Nielsen, Kjeld; Brunø, Thomas Ditlev

    2013-01-01

    Closed loop supply chains reducing waste, energy consumption and natural resource depletion which all contribute to more sustainable production and products. For mass customization however, the challenges of closed loop supply chains are emphasized by the large variety of inbound end-of-life prod......Closed loop supply chains reducing waste, energy consumption and natural resource depletion which all contribute to more sustainable production and products. For mass customization however, the challenges of closed loop supply chains are emphasized by the large variety of inbound end......-of-life products from customers which complicates handling and forecasting. This paper analyses these challenges in the specific context mass customization using theoretical considerations and three case studies....

  11. Bounce Loop Quantum Cosmology Corrected Gauss-Bonnet Gravity

    CERN Document Server

    Haro, J; Myagky, A N; Odintsov, S D; Oikonomou, V K

    2015-01-01

    We develop a Gauss-Bonnet extension of Loop Quantum Cosmology, by introducing holonomy corrections in modified $F(\\mathcal{G})$ theories of gravity. Within the context of our formalism, we provide a perturbative expansion in the critical density, a parameter characteristic of Loop Quantum Gravity theories, and we result in having leading order corrections to the classical $F(\\mathcal{G})$ theories of gravity. After extensively discussing the formalism, we present a reconstruction method that makes possible to find the Loop Quantum Cosmology corrected $F(\\mathcal{G})$ theory that can realize various cosmological scenarios. Specifically, we studied exponential and power-law bouncing cosmologies, emphasizing on the behavior near the bouncing point and in some cases, the behavior for all the values of the cosmic time is obtained. We exemplify our theoretical constructions by using bouncing cosmologies, and we investigate which Loop Quantum Cosmology corrected Gauss-Bonnet modified gravities can successfully reali...

  12. Titanium Loop Heat Pipes for Space Nuclear Radiators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will develop titanium Loop Heat Pipes (LHPs) that can be used in low-mass space nuclear radiators, such as...

  13. Timetable Optimization of Rail Transit Loop Line with Transfer Coordination

    National Research Council Canada - National Science Library

    Shi, Rui-Jia; Mao, Bao-Hua; Ding, Yong; Bai, Yun; Chen, Yao

    2016-01-01

    .... This is performed by adjusting the headways and dwell times of trains on the loop line. A genetic algorithm is applied to solve the proposed model, and a numerical example is used to verify its effectiveness...

  14. Analysis of Rectangular Loop Antenna Printed on Magnetic Plate

    OpenAIRE

    Taguchi, Mitsuo; Matsunaga, Yuki; Tanaka, Shinya; Shimoda, Hideaki

    2006-01-01

    In this paper, a rectangular loop antenna printed on the low loss magnetic plate is numerically and experimentally analyzed. In the numerical analysis, the electromagnetic simulator Micro-Stripes based on the transmission line matrix method is used.

  15. Gauge and Gravity Amplitudes from Trees to Loops

    DEFF Research Database (Denmark)

    Huang, Rijun

    This thesis describes two subjects that I mainly work on during my PhD study. They are both about scattering amplitudes, covering gravity and gauge theories, tree and loop level, with or without supersymmetry. The rst subject is Kawai-Lewellen-Tye(KLT) relation in field theory, which mysteriously...... for vanishing identities of Yang-Mills amplitudes as violation of linear symmetry groups based on KLT relation argument. The second subject is integrand reduction of multi-loop amplitude. The recent methods based on computational algebraic geometry make it possible to systematically study multi-loop amplitude...... with generalized unitarity cut. Using Grobner basis and primary decomposition, we thoroughly study integrand basis and solution space of equations from maximal unitarity cut for all 4-dimensional two-loop topologies. Algorithm and examples of this computation are illustrated in this thesis. We also study...

  16. Conformal anomaly of generalized form factors and finite loop integrals

    CERN Document Server

    Chicherin, Dmitry

    2017-01-01

    We reveal a new mechanism of conformal symmetry breaking at Born level. It occurs in generalized form factors with several local operators and an on-shell state of massless particles. The effect is due to hidden singularities on collinear configurations of the momenta. This conformal anomaly is different from the holomorphic anomaly of amplitudes. We present a number of examples in four and six dimensions. We find an application of the new conformal anomaly to finite loop momentum integrals with one or more massless legs. The collinear region around a massless leg creates a contact anomaly, made visible by the loop integration. The anomalous conformal Ward identity for an $\\ell-$loop integral is a 2nd-order differential equation whose right-hand side is an $(\\ell-1)-$loop integral. We show several examples, in particular the four-dimensional scalar double box.

  17. The Arabidopsis Basic/Helix-Loop-Helix Transcription Factor Family

    National Research Council Canada - National Science Library

    Gabriela Toledo-Ortiz; Enamul Huq; Peter H. Quail

    2003-01-01

    The basic/helix-loop-helix (bHLH) proteins are a superfamily of transcription factors that bind as dimers to specific DNA target sites and that have been well characterized in nonplant eukaryotes as important regulatory components...

  18. Nascent Connections: R-Loops and Chromatin Patterning.

    Science.gov (United States)

    Chédin, Frédéric

    2016-12-01

    RNA molecules, such as long noncoding RNAs (lncRNAs), have critical roles in regulating gene expression, chromosome architecture, and the modification states of chromatin. Recent developments suggest that RNA also influences gene expression and chromatin patterns through the interaction of nascent transcripts with their DNA template via the formation of co-transcriptional R-loop structures. R-loop formation over specific, conserved, hotspots occurs at thousands of genes in mammalian genomes and represents an important and dynamic feature of mammalian chromatin. Here, focusing primarily on mammalian systems, I describe the accumulating connections and possible mechanisms linking R-loop formation and chromatin patterning. The possible contribution of aberrant R-loops to pathological conditions is also discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Cognitive Modeling for Closed-Loop Task Mitigation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Intelligent Automation, Inc. (IAI) along with collaborators at the University of Iowa and Old Dominion University (ODU) developed an advanced closed-loop Adaptive...

  20. Comprehensive Prediction of Thermosyphon Characteristics in Reactor Passive Cooling System Simulation Loop FASSIP-01

    Directory of Open Access Journals (Sweden)

    H. Tjahjono

    2017-12-01

    Full Text Available Passive cooling mechanism for a nuclear reactor has been proven to be very important since the Fukushima Daiichi Reactor accident that was caused by active cooling system malfunction due to total loss of electrical power source. In the Center for Nuclear Reactor Technology and Safety of BATAN, the cooling mechanism was studied by using a natural circulation test loop named FASSIP-01 that applied thermosyphon mechanism of water inside pipes of 1” diameter. This study aimed to analytically predictthe thermal characteristics of the loop including its response time towards steady condition usingthe MATLAB calculation program. This prediction derived the influence of several parameters such as the heat transfer coefficient of the cooler side (h-cooler, the heater power, the elevation difference between the heater and cooler(DZ, and the effects of the insulation thickness of pipe (IT on the flowrate, temperature, and the heat power distribution across all components in the loop. The result showed that byavoiding boiling condition, for transferring the heater power of 1000 W and 2000 W,the needed h-cooler exceeds 200 and 400 W m-2°C-1, respectively. For a h-cooler of 200 W m-2°C-1, the circulation flow rate increased from 0.04 to 0.06 kg/s-1 for heater power increase from 1000 W to 2000 W. Those flow rates were decreased to 0.037 and 0.052 kgs-1 by increasing h-cooler to 1000 W m-2°C-1.The results were in agreement with other studies on rectangular loops in the literature.The time needed to reach 95 % towards steady state was predicted to be more than 13 hours. Reduction of this time to less than five hours was possible by reducing the heater tank volume from 100 L to 30 L or by modifying the starting heater input power.

  1. Nonlinear analysis of chaotic flow in a 3D closed-loop pulsating heat pipe

    CERN Document Server

    Pouryoussefi, S M

    2016-01-01

    Numerical simulation has been conducted for the chaotic flow in a 3D closed-loop pulsating heat pipe (PHP). Heat flux and constant temperature boundary conditions were applied for evaporator and condenser sections, respectively. Water and ethanol were used as working fluids. Volume of Fluid (VOF) method has been employed for two-phase flow simulation. Spectral analysis of temperature time series was carried out using Power Spectrum Density (PSD) method. Existence of dominant peak in PSD diagram indicated periodic or quasi-periodic behavior in temperature oscillations at particular frequencies. Correlation dimension values for ethanol as working fluid was found to be higher than that for water under the same operating conditions. Similar range of Lyapunov exponent values for the PHP with water and ethanol as working fluids indicated strong dependency of Lyapunov exponent to the structure and dimensions of the PHP. An O-ring structure pattern was obtained for reconstructed 3D attractor at periodic or quasi-peri...

  2. Plant Biomass Leaching for Nutrient Recovery in Closed Loop Systems Project

    Science.gov (United States)

    Zeitlin, Nancy P.; Wheeler, Raymond (Compiler); Lunn, Griffin

    2015-01-01

    Plants will be important for food and O2 production during long term human habitation in space. Recycling of nutrients (e.g., from waste materials) could reduce the resupply costs of fertilizers for growing these plants. Work at NASA's Kennedy Space Center has shown that ion exchange resins can extract fertilizer (plant essential nutrients) from human waste water, after which the residual brine could be treated with electrodialysis to recover more water and produce high value chemicals (e.g., acids and bases). In habitats with significant plant production, inedible biomass becomes a major source of solid waste. To "close the loop" we also need to recover useful nutrients and fertilizer from inedible biomass. We are investigating different approaches to retrieve nutrients from inedible plant biomass, including physical leaching with water, processing the biomass in bioreactors, changing the pH of leaching processing, and/or conducting multiple leaches of biomass residues.

  3. SLSF loop handling system. Volume I. Structural analysis. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, H.; Cowie, A.; Ma, D.

    1978-10-01

    SLSF loop handling system was analyzed for deadweight and postulated dynamic loading conditions, identified in Chapters II and III in Volume I of this report, using a linear elastic static equivalent method of stress analysis. Stress analysis of the loop handling machine is presented in Volume I of this report. Chapter VII in Volume I of this report is a contribution by EG and G Co., who performed the work under ANL supervision.

  4. Loop-Abort Faults on Supersingular Isogeny Cryptosystems

    OpenAIRE

    Gélin, Alexandre; Wesolowski, Benjamin

    2017-01-01

    International audience; Cryptographic schemes based on supersingular isogenies have become an active area of research in the field of post-quantum cryptography. We investigate the resistance of these cryptosystems to fault injection attacks. It appears that the iterative structure of the secret isogeny computation renders these schemes vulnerable to loop-abort attacks. Loop-abort faults allow to perform a full key recovery, bypassing all the previously introduced validation methods. Therefore...

  5. High-Power Liquid-Metal Heat-Transfer Loop

    Science.gov (United States)

    Bhandari, Pradeep; Fujita, Toshio

    1991-01-01

    Proposed closed-loop system for transfer of thermal power operates at relatively high differential pressure between vapor and liquid phases of liquid-metal working fluid. Resembles "capillary-pumped" liquid-metal heat-transfer loop except electric field across permselective barrier of beta alumina keeps liquid and vapor separate at heat-input end. Increases output thermal power, contains no moving parts, highly reliable and well suited to long-term unattended operation.

  6. Symmetry Reduced Loop Quantum Gravity: A Bird's Eye View

    CERN Document Server

    Ashtekar, Abhay

    2016-01-01

    This is a brief overview of the current status of symmetry reduced models in Loop Quantum Gravity. The goal is to provide an introduction to other more specialized and detailed reviews that follow. Since most of this work is motivated by the physics of the very early universe, I will focus primarily on Loop Quantum Cosmology and discuss quantum aspects of black holes only briefly.

  7. N >= 4 Supergravity Amplitudes from Gauge Theory at One Loop

    Energy Technology Data Exchange (ETDEWEB)

    Bern, Z.; /UCLA; Boucher-Veronneau, C.; /SLAC; Johansson, H.; /Saclay

    2011-08-19

    We expose simple and practical relations between the integrated four- and five-point one-loop amplitudes of N {ge} 4 supergravity and the corresponding (super-)Yang-Mills amplitudes. The link between the amplitudes is simply understood using the recently uncovered duality between color and kinematics that leads to a double-copy structure for gravity. These examples provide additional direct confirmations of the duality and double-copy properties at loop level for a sample of different theories.

  8. Chemical Looping Combustion of Methane: A Technology Development View

    OpenAIRE

    Rutuja Bhoje; Ganesh R. Kale; Nitin Labhsetwar; Sonali Borkhade

    2013-01-01

    Methane is a reliable and an abundantly available energy source occurring in nature as natural gas, biogas, landfill gas, and so forth. Clean energy generation using methane can be accomplished by using chemical looping combustion. This theoretical study for chemical looping combustion of methane was done to consider some key technology development points to help the process engineer choose the right oxygen carrier and process conditions. Combined maximum product (H2O + CO2) generation, weigh...

  9. Thermodynamic Analysis of an Electrochemically Driven Chemical Looping Heat Pump

    OpenAIRE

    James, Nelson A.; Braun, James E.; Groll, Eckhard A.; Horton, W. Travis

    2016-01-01

    Electrochemical cells have been widely explored for their use in high efficiency energy systems. In this paper a novel heat pump cycle is proposed which utilizes chemical looping driven by electrochemical cells. Chemical looping is a method that has been applied to various applications such as combustion and air separation. It consists of the cycling of a substance between different chemical compositions in order to produce a desired effect. When the chemical composition of a fluid changes, v...

  10. Finite-dimensional representations of twisted hyper loop algebras

    OpenAIRE

    Bianchi, Angelo; Moura, Adriano

    2012-01-01

    We investigate the category of finite-dimensional representations of twisted hyper loop algebras, i.e., the hyperalgebras associated to twisted loop algebras over finite-dimensional simple Lie algebras. The main results are the classification of the irreducible modules, the definition of the universal highest-weight modules, called the Weyl modules, and, under a certain mild restriction on the characteristic of the ground field, a proof that the simple modules and the Weyl modules for the twi...

  11. Methods of Temperature and Emission Measure Determination of Coronal Loops

    Science.gov (United States)

    Cirtain, J. W.; Schmelz, J. T.; Martens, P. C. H.

    2002-05-01

    Recent observational results from both SOHO-EIT and TRACE indicate that coronal loops are isothermal along their length (axially). These results are obtained from a narrowband filter ratio method that assumes that the plasma is isothermal along the line of sight (radially). However, these temperatures vary greatly from those derived from differential emission measure (DEM) curves produced from spectral lines recorded by SOHO-CDS. The DEM results indicate that the loops are neither axially nor radially isothermal. This discrepancy was investigated by Schmelz et al. (2001). They chose pairs of iron lines from the same CDS data set to mimic the EIT and TRACE loop results. Ratios of different lines gave different temperatures, indicating that the plasma was not radially isothermal. In addition the results indicated that the loop was axially isothermal, even though the DEM analysis of the same data showed this result to be false. Here we have analyzed the EIT data for the CDS loop published by Schmelz et al. (2001). We took the ratios of the 171-to-195 and 195-to-284 filter data, and made temperature maps of the loop. The results indicate that the loop is axially isothermal, but different temperatures were found for each pair of filters. Both ratio techniques force the resultant temperature to lie within the range where the response functions (for filters) or the emissivity functions (for lines) overlap; isothermal loops are therefore a byproduct of the analysis. This conclusion strengthens support for the idea that temperature and emission measure results from filter ratio methods may be misleading or even drastically wrong. This research was funded in part by the NASA/TRACE MODA grant for Montana State University. Solar physics research at the University of Memphis is supported by NASA grant NAG5-9783.

  12. Two-Loop Four-Gluon Amplitudes from Numerical Unitarity

    Science.gov (United States)

    Abreu, S.; Cordero, F. Febres; Ita, H.; Jaquier, M.; Page, B.; Zeng, M.

    2017-10-01

    We present the first numerical computation of two-loop amplitudes based on the unitarity method. As a proof of principle, we compute the four-gluon process in the leading-color approximation. We discuss the new method, analyze its numerical properties, and apply it to reconstruct the analytic form of the amplitudes. The numerical method is universal, and can be automated to provide multiscale two-loop computations for phenomenologically relevant signatures at hadron colliders.

  13. Belokurov-Usyukina loop reduction in non-integer dimension

    Science.gov (United States)

    Gonzalez, Ivan; Kondrashuk, Igor

    2013-03-01

    Belokurov-Usyukina loop reduction method has been proposed in 1983 to reduce a number of rungs in triangle ladder-like diagram by one. The disadvantage of the method is that it works in d = 4 dimensions only and it cannot be used for calculation of amplitudes in field theory in which we are required to put all the incoming and outgoing momenta on shell. We generalize the Belokurov-Usyukina loop reduction technique to non-integer d = 4 - 2ɛ dimensions. In this paper we show how a two-loop triangle diagram with particular values of indices of scalar propagators in the position space can be reduced to a combination of three one-loop scalar diagrams. It is known that any one-loop massless momentum integral can be presented in terms of Appell's function F 4. This means that particular diagram considered in the present paper can be represented in terms of Appell's function F 4 too. Such a generalization of Belokurov-Usyukina loop reduction technique allows us to calculate that diagram by this method exactly without decomposition in terms of the parameter ɛ.

  14. Asymmetric structure of five and six membered DNA hairpin loops

    Science.gov (United States)

    Baumann, U.; Chang, S.

    1995-01-01

    The tertiary structure of nucleic acid hairpins was elucidated by means of the accessibility of the single-strand-specific nuclease from mung bean. This molecular probe has proven especially useful in determining details of the structural arrangement of the nucleotides within a loop. In this study 3'-labeling is introduced to complement previously used 5'-labeling in order to assess and to exclude possible artifacts of the method. Both labeling procedures result in mutually consistent cleavage patterns. Therefore, methodological artifacts can be excluded and the potential of the nuclease as structural probe is increased. DNA hairpins with five and six membered loops reveal an asymmetric loop structure with a sharp bend of the phosphate-ribose backbone between the second and third nucleotide on the 3'-side of a loop. These hairpin structures differ from smaller loops with 3 or 4 members, which reveal this type of bend between the first and second 3' nucleotide, and resemble with respect to the asymmetry anticodon loops of tRNA.

  15. Natural Circulation Characteristics of a Symmetric Loop under Inclined Conditions

    Directory of Open Access Journals (Sweden)

    Xingtuan Yang

    2014-01-01

    Full Text Available Natural circulation is an important process for primary loops of some marine integrated reactors. The reactor works under inclined conditions when severe accidents happen to the ship. In this paper, to investigate the characteristics of natural circulation, experiments were conducted in a symmetric loop under the inclined angle of 0~45°. A CFD model was also set up to predict the behaviors of the loop beyond the experimental scope. Total circulation flow rate decreases with the increase of inclined angle. Meanwhile one circulation is depressed while the other is enhanced, and accordingly the disparity between the branch circulations arises and increases with the increase of inclined angle. Circulation only takes place in one branch circuit at large inclined angle. Also based on the CFD model, the influences of flow resistance distribution and loop configuration on natural circulation are predicted. The numerical results show that to design the loop with the configuration of big altitude difference and small width, it is favorable to reduce the influence of inclination; however too small loop width will cause severe reduction of circulation ability at large angle inclination.

  16. Loop versus divided colostomy for the management of anorectal malformations.

    Science.gov (United States)

    Oda, Omar; Davies, Dafydd; Colapinto, Kimberly; Gerstle, J Ted

    2014-01-01

    The purpose of this study was to compare the clinical outcomes of loop and divided colostomies in patients with anorectal malformations (ARM). We performed a retrospective cohort study reviewing the medical records of all patients with ARM managed with diverting colostomies between 2000 and 2010 at our institution. Independent variables and outcomes of stoma complications were analyzed by parametric measures and logistic regression. One hundred forty-four patients managed with a colostomy for ARM were evaluated (37.5% females, 50.7% loop, 49.3% divided). The incidence of patients with loop and divided colostomies who developed stoma-related complications was 31.5 and 15.5%, respectively (p=0.031). The incidence of prolapse was 17.8 and 2.8%, respectively (p=0.005). Multivariable-logistic regression controlling for other significant independent variables found loop colostomies to be positively associated with the development of a stoma complication (OR 3.13, 95%CI (1.09, 8.96), p=0.033). When individual complications were evaluated, it was only stoma prolapse that was more likely in patients with loop colostomies (OR 8.75, 95%CI (1.74, 44.16), p=0.009). Because of the higher incidence of prolapse, loop colostomies were found to be associated with a higher total incidence of complications than divided stomas. The development of other complications, including urinary tract infections (UTIs) and megarectum, were independent of the type of colostomy performed. © 2014.

  17. Are scattering amplitudes dual to super Wilson loops?

    CERN Document Server

    Belitsky, A V; Sokatchev, E

    2012-01-01

    The MHV scattering amplitudes in planar N=4 SYM are dual to bosonic light-like Wilson loops. We explore various proposals for extending this duality to generic non-MHV amplitudes. The corresponding dual object should have the same symmetries as the scattering amplitudes and be invariant to all loops under the chiral half of the N=4 superconformal symmetry. We analyze the recently introduced supersymmetric extensions of the light-like Wilson loop (formulated in Minkowski space-time) and demonstrate that they have the required symmetry properties at the classical level only, up to terms proportional to field equations of motion. At the quantum level, due to the specific light-cone singularities of the Wilson loop, the equations of motion produce a nontrivial finite contribution which breaks some of the classical symmetries. As a result, the quantum corrections violate the chiral supersymmetry already at one loop, thus invalidating the conjectured duality between Wilson loops and non-MHV scattering amplitudes. W...

  18. Stability of intramolecular quadruplexes: sequence effects in the central loop.

    Science.gov (United States)

    Guédin, Aurore; Alberti, Patrizia; Mergny, Jean-Louis

    2009-09-01

    Hundreds of thousands of putative quadruplex sequences have been found in the human genome. It is important to understand the rules that govern the stability of these intramolecular structures. In this report, we analysed sequence effects in a 3-base-long central loop, keeping the rest of the quadruplex unchanged. A first series of 36 different sequences were compared; they correspond to the general formula GGGTTTGGGHNHGGGTTTGGG. One clear rule emerged from the comparison of all sequence motifs: the presence of an adenine at the first position of the loop was significantly detrimental to stability. In contrast, adenines have no detrimental effect when present at the second or third position of the loop. Cytosines may either have a stabilizing or destabilizing effect depending on their position. In general, the correlation between the T(m) or DeltaG degrees in sodium and potassium was weak. To determine if these sequence effects could be generalized to different quadruplexes, specific loops were tested in different sequence contexts. Analysis of 26 extra sequences confirmed the general destabilizing effect of adenine as the first base of the loop(s). Finally, analysis of some of the sequences by microcalorimetry (DSC) confirmed the differences found between the sequence motifs.

  19. Demonstration of Noncorrosive, Capacitance- Based Water-Treatment Technology for Chilled-Water Cooling Systems

    Science.gov (United States)

    2014-09-01

    ER327E0031137500. Adjustable length E/R probe with 40-mil, epoxy sealed , wire loop element in carbon steel/copper on ¾-in. MNPT nylon fitting. Transmitters: IN2500E...compared to when chemically treating the tower water 2. The water savings and use of gray water could con- tribute to LEED points and compliance

  20. Depth distribution of Frank loop defects formed in ion-irradiated stainless steel and its dependence on Si addition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dongyue, E-mail: dychen@safety.n.t.u-tokyo.ac.jp [The University of Tokyo, Department of Nuclear Engineering and Management, School of Engineering, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656 (Japan); Murakami, Kenta [The University of Tokyo, Nuclear Professional School, School of Engineering, 2-22 Shirakata-Shirane, Tokai-mura, Ibaraki 319-1188 (Japan); Dohi, Kenji; Nishida, Kenji; Soneda, Naoki [Central Research Institute of Electric Power Industry, 2-11-1 Iwado-kita, Komae, Tokyo 201-8511 (Japan); Li, Zhengcao, E-mail: zcli@tsinghua.edu.cn [Tsinghua University, School of Materials Science and Engineering, Beijing 100084 (China); Liu, Li; Sekimura, Naoto [The University of Tokyo, Department of Nuclear Engineering and Management, School of Engineering, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656 (Japan)

    2015-12-15

    Although heavy ion irradiation is a good tool to simulate neutron irradiation-induced damages in light water reactor, it produces inhomogeneous defect distribution. Such difference in defect distribution brings difficulty in comparing the microstructure evolution and mechanical degradation between neutron and heavy ion irradiation, and thus needs to be understood. Stainless steel is the typical structural material used in reactor core, and could be taken as an example to study the inhomogeneous defect depth distribution in heavy ion irradiation and its influence on the tested irradiation hardening by nano-indentation. In this work, solution annealed stainless steel model alloys are irradiated by 3 MeV Fe{sup 2+} ions at 400 °C to 3 dpa to produce Frank loops that are mainly interstitial in nature. The silicon content of the model alloys is also tuned to change point defect diffusion, so that the loop depth distribution influenced by diffusion along the irradiation beam direction could be discussed. Results show that in low Si (0% Si) and base Si (0.42% Si) samples the depth distribution of Frank loop density quite well matches the dpa profile calculated by the SRIM code, but in high Si sample (0.95% Si), the loop number density in the near-surface region is very low. One possible explanation could be Si’s role in enhancing the effective vacancy diffusivity, promoting recombination and thus suppressing interstitial Frank loops, especially in the near-surface region, where vacancies concentrate. By considering the loop depth distribution, the tested irradiation hardening is successfully explained by the Orowan model. A hardening coefficient of around 0.30 is obtained for all the three samples. This attempt in interpreting hardening results may make it easier to compare the mechanical degradation between different irradiation experiments.

  1. Gulf of Mexico Loop Current path variability

    Science.gov (United States)

    Donohue, K. A.; Watts, D. R.; Hamilton, P.; Leben, R.; Kennelly, M.; Lugo-Fernández, A.

    2016-12-01

    Loop Current, LC, path variability exhibits a continuum of spatial and temporal scales, all are called meanders in this work. They arise from a variety of processes, including short and long waves, frontal eddies with or without closed cores and developing baroclinic instability. They have been extensively studied with satellite sea surface temperature SST, and height, SSH. Yet, these systems provide an incomplete view into LC meandering: SST measurements are hampered by cloud coverage and low thermal contrast in summer months and SSH measurements by altimeter temporal and spatial resolution. In an effort to resolve LC meander temporal and spatial scales, they are investigated using a mesoscale resolving in situ array deployed in the Gulf of Mexico. The array, which consisted of twenty-five inverted echo sounders with pressure gauges, PIES, and current meter moorings, was deployed April 2009 and recovered in October-November 2011. The broad extent of the array, nominally 89° W to 85° W, 25° N to 27° N, enabled quantitative mapping of the regional circulation. LC meander properties are characterized as a function of spatial distribution of energy, frequency, wavenumber, and phase speed. Dispersion characteristics and meander scales are comparable to those found in the Gulf Stream. Phase speeds increase with frequency and range from 8 to 50 km d-1. Wavelengths associated with each band are as follows: 460 km for the 100 to 40 d band, 350 km for the 40 to 20 d band, 270 km for the 20 to 10 d band and 230 km for the 10 to 3 d band. The strongest variability is in the 100 to 40 d band. Spatially the 100 to 40 d variability is concentrated to east of the Mississippi Fan, growing and propagating downstream along the eastern portion of the LC. Meanders between 40 and 20 d propagate along the full encompassed length of the LC. Their temporal amplitudes peak at the time of LC eddy detachment and separation. Meanders with shorter periods than 20 d do not always propagate

  2. Siphon flow in a cool magnetic loop

    Science.gov (United States)

    Bethge, C.; Beck, C.; Peter, H.; Lagg, A.

    2012-01-01

    Context. Siphon flows that are driven by a gas pressure difference between two photospheric footpoints of different magnetic field strength connected by magnetic field lines are a well-studied phenomenon in theory, but observational evidence is scarce. Aims. We investigate the properties of a structure in the solar chromosphere in an active region to find out whether the feature is consistent with a siphon flow in a magnetic loop filled with chromospheric material. Methods. We derived the line-of-sight (LOS) velocity of several photospheric spectral lines and two chromospheric spectral lines, Ca II H 3968.5 *Aring; and He I 10830 Å, in spectropolarimetric observations of NOAA 10978 done with the Tenerife Infrared Polarimeter (TIP-II) and the POlarimetric LIttrow Spectrograph (POLIS). The structure can be clearly traced in the LOS velocity maps and the absorption depth of He I. The magnetic field configuration in the photosphere is inferred directly from the observed Stokes parameters and from inversions with the HELIX+ code. Data from the full-disk Chromospheric Telescope (ChroTel) in He I in intensity and LOS velocity are used for tracking the temporal evolution of the flow, along with TRACE Fe IX/X 171 Å data for additional information about coronal regions related to the structure under investigation. Results. The inner end of the structure is located in the penumbra of a sunspot. It shows downflows whose strength decreases with decreasing height in the atmosphere. The flow velocity in He I falls abruptly from above 40 km s-1 to about zero further into the penumbra. A slight increase of emission is seen in the Ca II H spectra at the endpoint. At the outer end of the structure, the photospheric lines that form higher up in the atmosphere show upflows that accelerate with height. The polarization signal near the outer end shows a polarity opposite to that of the sunspot, the magnetic field strength of 580 G is roughly half as large as at the inner end. The

  3. Picophytoplankton physiology and the microbial loop

    Science.gov (United States)

    Stawiarski, Beate

    2013-04-01

    Physiological observations are needed for a better understanding of the complexity of marine ecosystem processes. This information is important for a better model formulation and parameterisation to identify the consequences of, and feedbacks to, global change and to make future projections. Picophytoplankton form the smallest component of the phytoplankton community (˜ 3μm) and show a substantial contribution to phytoplankton biomass in oligotrophic oceans. Here they also have an important function as primary producers in the microbial loop. They include cyanobacteria, represented by Prochlorococcus and Synechococcus, and picoeukaryotes. The aim of this project is to achieve a better representation of picophytoplankton in the global biogeochemical model PlankTOM 10. PlankTOM 10 simplifies the complex ecosystem into 10 conceptual groups also known as plankton functional types (PFTs). These groups of organisms are defined by physiological and biochemical parameters (6 of phytoplankton, 3 of zooplankton and 1 of bacteria). Furthermore, the question will be addressed, whether picophytoplankton are typical K-strategists with low minimum nutrient and high maximum chlorophyll quota relative to carbon, or by having superior nutrient uptake kinetics and light harvesting (high αChl). Laboratory experiments showed that the smaller picoprokaryotes respond faster to increasing light intensities than their picoeukaryotic counterpart. Preliminary data show that the initial slope of the photosynthesis vs. irradiance curve (αChl) of picoprokaryotes is about 1.5 times higher than of picoeukaryotes. This is consistent with their common distribution at the deep chlorophyll maximum. The maximum chlorophyll quota are not significantly different. Temperature experiments confirmed that the maximum growth rates of picophytoplankton at the optimum temperature (0.47 ± 0.17 d-1 for prokaryotes and 1.05 ± 0.47 d-1 for eukaryotes) are significantly lower than of diatoms (1.57 ± 0.73 d-1

  4. Chemical looping reforming of generator gas

    Energy Technology Data Exchange (ETDEWEB)

    Mendiara, T.; Jensen, Anker; Glarborg, P.

    2010-02-15

    The main objective of this work is to investigate the carbon deposition during reforming of hydrocarbons in a Chemical Looping Reformer (CLR). This knowledge is needed to asses the viability of the CLR technology in reforming tar from biomass gasification preserving lighter hydrocarbons and minimizing the carbon formation during the process. Two different setups were used to test the reactivity of the different samples in the conditions of interest for the tar reforming process: 1) Fixed bed flow reactor (FR), and 2) Thermogravimetric analyzer (TGA). In the experiments, the gas atmosphere was switched from reducing to oxidizing atmosphere in every cycle. During the oxidizing cycle, the carrier was regenerated using a mixture of oxygen and nitrogen. Four different oxygen carriers based on nickel (Ni40 and Ni60), manganese (Mn) and ilmenite (Fe) were tested. In the tests, toluene was used to simulate the tars. The Fe and the Mn carrier reacted to a small extent with methane at the highest temperature studied, 800 degrees C. The Ni-carriers did not react at 600 degrees C at first, but they showed some reactivity after having been activated at the higher temperature. Carbon formation occurred with the Ni-carriers, more so with the Ni60 than the Ni40. Ni40, Mn and Fe were activated at the higher temperature. However, Fe showed only low capacity. Ni60 showed no capability of tar reforming. Ni40 showed a high tendency to carbon formation at 800 degrees C, but the formation could be lowered by changing some parameters. Mn formed almost no carbon. Ni40 and Mn were chosen for further studies. Carbon deposition occurred for both Ni40 and Mn, but the amount deposited for Ni40 was about 10 times bigger. Ni40 reacted with the methane and toluene only at 800 degrees C. The conversion over Mn was not as big as for toluene alone. Carbon was formed from carbon monoxide on the Ni40 carrier and on the Mn, but to a much less extent on the latter one. The presence of hydrogen decreased

  5. Chemical looping reactor system design double loop circulating fluidized bed (DLCFB)

    Energy Technology Data Exchange (ETDEWEB)

    Bischi, Aldo

    2012-05-15

    Chemical looping combustion (CLC) is continuously gaining more importance among the carbon capture and storage (CCS) technologies. It is an unmixed combustion process which takes place in two steps. An effective way to realize CLC is to use two interconnected fluidized beds and a metallic powder circulating among them, acting as oxygen carrier. The metallic powder oxidizes at high temperature in one of the two reactors, the air reactor (AR). It reacts in a highly exothermic reaction with the oxygen of the injected fluidising air. Afterwards the particles are sent to the other reactor where the fuel is injected, the fuel reactor (FR). There, they transport heat and oxygen necessary for the reaction with the injected fuel to take place. At high temperatures, the particle's oxygen reacts with the fuel producing Co2 and steam, and the particles are ready to start the loop again. The overall reaction, the sum of the enthalpy changes of the oxygen carrier oxidation and reduction reactions, is the same as for the conventional combustion. Two are the key features, which make CLC promising both for costs and capture efficiency. First, the high inherent irreversibility of the conventional combustion is avoided because the energy is utilized stepwise. Second, the Co2 is intrinsically separated within the process; so there is in principle no need either of extra carbon capture devices or of expensive air separation units to produce oxygen for oxy-combustion. A lot of effort is taking place worldwide on the development of new chemical looping oxygen carrier particles, reactor systems and processes. The current work is focused on the reactor system: a new design is presented, for the construction of an atmospheric 150kWth prototype working with gaseous fuel and possibly with inexpensive oxygen carriers derived from industrial by-products or natural minerals. It consists of two circulating fluidized beds capable to operate in fast fluidization regime; this will increase the

  6. Microbial Community Dynamics of a Simulated Chloraminated Drinking Water Distribution System Subjected to Episodes of Nitrification

    Science.gov (United States)

    Bacterial populations were examined in a simulated chloraminated drinking water distribution system (i.e. loop). The loop (BW-AB-I) received chlorinated municipal water (BW-C) amended with ammonia (2mg/L monochloramine). After six years of continuous operation, the operational ...

  7. Scheduling and Allocation of Non-Manifest Loops on Hardware Graph-Models

    NARCIS (Netherlands)

    Mansour, O.; Etalle, Sandro; Krol, Th.; Karelse, F.

    2001-01-01

    We address the problem of scheduling non-manifest data dependant periodic loops for high throughput DSP-applications based on a streaming data model. In contrast to manifest loops, non-manifest data dependant loops are loops where the number of iterations needed in order to perform a calculation is

  8. Higgs boson mass in the standard model at two-loop order and beyond

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Stephen P.; Robertson, David G.

    2014-10-01

    We calculate the mass of the Higgs boson in the standard model in terms of the underlying Lagrangian parameters at complete 2-loop order with leading 3-loop corrections. A computer program implementing the results is provided. The program also computes and minimizes the standard model effective potential in Landau gauge at 2-loop order with leading 3-loop corrections.

  9. Influence of cross-sectional ratio of down comer to riser on the efficiency of liquid circulation in loop air lift bubble column

    Directory of Open Access Journals (Sweden)

    Yamamoto Tatsumi

    2017-01-01

    Full Text Available Loop type bubble columns have good performance of liquid circulation and mass transfer by airlift effect, where the liquid circulation time is an important measurable characteristic parameter. This parameter is affected by the column construction, the aspect ratio of the column, the cross-sectional area ratio of down comer to riser (R, and the superficial gas velocity in the riser (UGR. In this work, the mean gas holdup and the liquid circulation time (TC have been measured in four types of loop airlift type bubble column: concentric tube internal loop airlift type, rectangular internal loop airlift type, external loop airlift type, external loop airlift with separator. Air and tap water were used as gas and liquid phase, respectively. The results have demonstrated that the mean gas holdup in riser increases in proportion to UGR, and that it in downcomer changes according to the geometric parameters of each bubble column. TC has been found to conform to an empirical equation which depends on UGR and the length of draft tube or division plate in the region of 0.33 < R < 1.

  10. Influence of cross-sectional ratio of down comer to riser on the efficiency of liquid circulation in loop air lift bubble column

    Science.gov (United States)

    Yamamoto, Tatsumi; Kawasaki, Hiroyuki; Mori, Hidetoshi

    2017-11-01

    Loop type bubble columns have good performance of liquid circulation and mass transfer by airlift effect, where the liquid circulation time is an important measurable characteristic parameter. This parameter is affected by the column construction, the aspect ratio of the column, the cross-sectional area ratio of down comer to riser (R), and the superficial gas velocity in the riser (UGR). In this work, the mean gas holdup and the liquid circulation time (TC) have been measured in four types of loop airlift type bubble column: concentric tube internal loop airlift type, rectangular internal loop airlift type, external loop airlift type, external loop airlift with separator. Air and tap water were used as gas and liquid phase, respectively. The results have demonstrated that the mean gas holdup in riser increases in proportion to UGR, and that it in downcomer changes according to the geometric parameters of each bubble column. TC has been found to conform to an empirical equation which depends on UGR and the length of draft tube or division plate in the region of 0.33 < R < 1.

  11. Status of the Redesign of the Extravehicular Mobility Unit Airlock Cooling Loop Recovery Assembly

    Science.gov (United States)

    Steele, John; Arnold, Dane; Peyton, Barbara; Rector, Tony; Jennings, Mallory

    2017-01-01

    During EVA (Extravehicular Activity) 23 aboard the ISS (International Space Station) on 07/16/2013 an episode of water in the EMU (Extravehicular Mobility Unit) helmet occurred, necessitating a termination of the EVA (Extravehicular Activity) shortly after it began. The root cause of the failure was determined to be ground-processing short-comings of the ALCLR Ion Beds which led to various levels of contaminants being introduced into the Ion Beds before they left the ground. The Ion Beds were thereafter used to perform on-orbit routine scrubbing operations for the EMU cooling water loop which led to the failure. The root cause investigation identified several areas for improvement of the ALCLR Assembly which have since been initiated. Enhanced washing techniques for the ALCLR Ion Bed have been developed and implemented. On-orbit cooling water conductivity and pH analysis capability to allow the astronauts to monitor proper operation of the ALCLR Ion Bed during scrubbing operation have been investigated and are being incorporated. A simplified means to acquire on-orbit EMU cooling water samples has been designed as well. Finally, an inherently cleaner organic adsorbent to replace the current lignite-based activated carbon, and a non-separable replacement for the separable mixed ion exchange resin have been selected. These efforts are being undertaken to enhance the performance and reduce the risk associated with operations to ensure the long-term health of the EMU cooling water circuit. The intent of this paper is to provide an update of the effort to re-design the ALCLR (Airlock Cooling Loop Recovery) hardware. Last year, this effort was in the early stages of concept development and test which was reported in ICES Paper ICES-2016-221. Those phases are now complete and the final outcomes, as well as plans to build and field the hardware, are being reported on.

  12. Three Dimensional Numerical Modeling of Loop-Loop Electromagnetic Data at Low Induction Numbers

    OpenAIRE

    SELEPENG, AME THATO

    2016-01-01

    An artificial groundwater recharge experiment was conducted in a pyroclastic plateau in Kagoshima Prefecture in Japan, and time-lapse electrical resistivity data were collected to monitor the recharge process. In the experiment, time-efficient in-line resistivity surveys were performed along four intersecting lines, because a large amount of water was released from two recharge areas and a relatively fast migration of water into the vadose zone was expected. The migration of recharged water m...

  13. Cooling of High Heat Flux Flat Surface with Nanofluid Assisted Convective Loop: Experimental Assessment

    Directory of Open Access Journals (Sweden)

    Arya Amir

    2017-12-01

    Full Text Available Experimental investigation was conducted on the thermal performance and pressure drop of a convective cooling loop working with ZnO aqueous nanofluids. The loop was used to cool a flat heater connected to an AC autotransformer. Influence of different operating parameters, such as fluid flow rate and mass concentration of nanofluid on surface temperature of heater, pressure drop, friction factor and overall heat transfer coefficient was investigated and briefly discussed. Results of this study showed that, despite a penalty for pressure drop, ZnO/water nanofluid was a promising coolant for cooling the micro-electronic devices and chipsets. It was also found that there is an optimum for concentration of nanofluid so that the heat transfer coefficient is maximum, which was wt. % = 0.3 for ZnO/water used in this research. In addition, presence of nanoparticles enhanced the friction factor and pressure drop as well; however, it is not very significant in comparison with those of registered for the base fluid.

  14. Closed-Loop Control of Humidification for Artifact Reduction in Capacitive ECG Measurements.

    Science.gov (United States)

    Leicht, Lennart; Eilebrecht, Benjamin; Weyer, Soren; Leonhardt, Steffen; Teichmann, Daniel

    2017-04-01

    Recording biosignals without the need for direct skin contact offers new opportunities for ubiquitous health monitoring. Electrodes with capacitive coupling have been shown to be suitable for the monitoring of electrical potentials on the body surface, in particular ECG. However, due to triboelectric charge generation and motion artifacts, signal and thus diagnostic quality is inferior to galvanic coupling. Active closed-loop humidification of capacitive electrodes is proposed in this work as a new concept to improve signal quality. A capacitive ECG recording system integrated into a common car seat is presented. It can regulate the micro climate at the interface of electrode and patient by actively dispensing water vapour and monitoring humidity in a closed-loop approach. As a regenerative water reservoir, silica gel is used. The system was evaluated with respect to subjective and objective ECG signal quality. Active humidification was found to have a significant positive effect in case of previously poor quality. Also, it had no diminishing effect in case of already good signal quality.

  15. 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.

  16. A Bayesian Approach to Period Searching in Solar Coronal Loops

    Science.gov (United States)

    Scherrer, Bryan; McKenzie, David

    2017-03-01

    We have applied a Bayesian generalized Lomb-Scargle period searching algorithm to movies of coronal loop images obtained with the Hinode X-ray Telescope (XRT) to search for evidence of periodicities that would indicate resonant heating of the loops. The algorithm makes as its only assumption that there is a single sinusoidal signal within each light curve of the data. Both the amplitudes and noise are taken as free parameters. It is argued that this procedure should be used alongside Fourier and wavelet analyses to more accurately extract periodic intensity modulations in coronal loops. The data analyzed are from XRT Observation Program #129C: “MHD Wave Heating (Thin Filters),” which occurred during 2006 November 13 and focused on active region 10293, which included coronal loops. The first data set spans approximately 10 min with an average cadence of 2 s, 2″ per pixel resolution, and used the Al-mesh analysis filter. The second data set spans approximately 4 min with a 3 s average cadence, 1″ per pixel resolution, and used the Al-poly analysis filter. The final data set spans approximately 22 min at a 6 s average cadence, and used the Al-poly analysis filter. In total, 55 periods of sinusoidal coronal loop oscillations between 5.5 and 59.6 s are discussed, supporting proposals in the literature that resonant absorption of magnetic waves is a viable mechanism for depositing energy in the corona.

  17. 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

  18. Tiling arbitrarily nested loops by means of the transitive

    Directory of Open Access Journals (Sweden)

    Bielecki Włodzimierz

    2016-12-01

    Full Text Available A novel approach to generation of tiled code for arbitrarily nested loops is presented. It is derived via a combination of the polyhedral and iteration space slicing frameworks. Instead of program transformations represented by a set of affine functions, one for each statement, it uses the transitive closure of a loop nest dependence graph to carry out corrections of original rectangular tiles so that all dependences of the original loop nest are preserved under the lexicographic order of target tiles. Parallel tiled code can be generated on the basis of valid serial tiled code by means of applying affine transformations or transitive closure using on input an inter-tile dependence graph whose vertices are represented by target tiles while edges connect dependent target tiles. We demonstrate how a relation describing such a graph can be formed. The main merit of the presented approach in comparison with the well-known ones is that it does not require full permutability of loops to generate both serial and parallel tiled codes; this increases the scope of loop nests to be tiled.

  19. Positive feedback promotes oscillations in negative feedback loops.

    Science.gov (United States)

    Ananthasubramaniam, Bharath; Herzel, Hanspeter

    2014-01-01

    A simple three-component negative feedback loop is a recurring motif in biochemical oscillators. This motif oscillates as it has the three necessary ingredients for oscillations: a three-step delay, negative feedback, and nonlinearity in the loop. However, to oscillate, this motif under the common Goodwin formulation requires a high degree of cooperativity (a measure of nonlinearity) in the feedback that is biologically "unlikely." Moreover, this recurring negative feedback motif is commonly observed augmented by positive feedback interactions. Here we show that these positive feedback interactions promote oscillation at lower degrees of cooperativity, and we can thus unify several common kinetic mechanisms that facilitate oscillations, such as self-activation and Michaelis-Menten degradation. The positive feedback loops are most beneficial when acting on the shortest lived component, where they function by balancing the lifetimes of the different components. The benefits of multiple positive feedback interactions are cumulative for a majority of situations considered, when benefits are measured by the reduction in the cooperativity required to oscillate. These positive feedback motifs also allow oscillations with longer periods than that determined by the lifetimes of the components alone. We can therefore conjecture that these positive feedback loops have evolved to facilitate oscillations at lower, kinetically achievable, degrees of cooperativity. Finally, we discuss the implications of our conclusions on the mammalian molecular clock, a system modeled extensively based on the three-component negative feedback loop.

  20. System design description for GCFR-core flow test loop

    Energy Technology Data Exchange (ETDEWEB)

    Huntley, W.R.; Grindell, A.G.

    1980-12-01

    The Core Flow Test Loop is a high-pressure, high-temperature, out-of-reactor helium circulation system that is being constructed to permit detailed study of the thermomechanical and thermal performance at prototypic steady-state and transient operating conditions of simulated segments of core assemblies for a GCFR Demonstration Plant, as designed by General Atomic Company. It will also permit the expermental verification of predictive analytical models of the GCFR core assemblies needed to reduce operational and safety uncertainties of the GCFR. Full-sized blanket assemblies and segments of fuel rod and control rod fuel assemblies will be simulated with test bundles of electrically powered fuel rod or blanket rod simulators. The loop will provide the steady-state and margin test requirements of bundle power and heat removal, and of helium coolant flow rate, pressure, and temperature for test bundles having up to 91 rods; these requirements set the maximum power, coolant helium flow, and thermal requirements for the loop. However, the size of the test vessel that contains the test bundles will be determined by the bundles that simulate a full-sized GCFR blanket assembly. The loop will also provide for power and coolant transients to simulate transient operation of GCFR core assemblies, including the capability for rapid helium depressurization to simulate the depressurization class of GCFR accidents. In addition, the loop can be used as an out-of-reactor test bed for characterizing in-reactor test bundle configurations.