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Sample records for actively cooled structures

  1. Temperature Regulator for Actively Cooled Structures

    NASA Technical Reports Server (NTRS)

    Blosser, Max (Inventor); Kelly, H. Neale (Inventor)

    1995-01-01

    In active cooling of a structure it is beneficial to use a plurality of passages for conducting coolant to various portions of the structure. Since most structures do not undergo isotropic thermal loads it is desirable to allow for variation in coolant flow to each area of the structure. The present invention allows for variable flow by a variation of the area of a portion of each of the coolant passages. Shape memory alloys and bi-material springs are used to produce passages that change flow area as a function of temperature.

  2. A fuselage/tank structure study for actively cooled hypersonic cruise vehicles: Active cooling system analysis

    NASA Technical Reports Server (NTRS)

    Stone, J. E.

    1975-01-01

    The effects of fuselage cross section and structural arrangement on the performance of actively cooled hypersonic cruise vehicles are investigated. An active cooling system which maintains the aircraft's entire surface area at temperatures below 394 K at Mach 6 is developed along with a hydrogen fuel tankage thermal protection system. Thermodynamic characteristics of the actively cooled thermal protection systems established are summarized. Design heat loads and coolant flowrate requirements are defined for each major structural section and for the total system. Cooling system weights are summarized at the major component level. Conclusions and recommendations are included.

  3. Actively cooled plate fin sandwich structural panels for hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Smith, L. M.; Beuyukian, C. S.

    1979-01-01

    An unshielded actively cooled structural panel was designed for application to a hypersonic aircraft. The design was an all aluminum stringer-stiffened platefin sandwich structure which used a 60/40 mixture of ethylene glycol/water as the coolant. Eight small test specimens of the basic platefin sandwich concept and three fatigue specimens from critical areas of the panel design was fabricated and tested (at room temperature). A test panel representative of all features of the panel design was fabricated and tested to determine the combined thermal/mechanical performance and structural integrity of the system. The overall findings are that; (1) the stringer-stiffened platefin sandwich actively cooling concept results in a low mass design that is an excellent contender for application to a hypersonic vehicle, and (2) the fabrication processes are state of the art but new or modified facilities are required to support full scale panel fabrication.

  4. Flightweight radiantly and actively cooled panel: thermal and structural performance

    SciTech Connect

    Shore, C.P.; Nowak, R.J.; Kelly, H.N.

    1982-01-01

    A 2- by 4-ft flightweight panel was subjected to thermal/structural tests representative of design flight conditions for a Mach 6.7 transport and to off-design conditions simulating flight maneuvers and cooling system failures. The panel utilized Rene 41 heat shields backed by a thin layer of insulation to radiate away most of the 12 Btu/ft/sup 2/-sec incident heating. A solution of ethylene glycol in water circulating through tubes in an aluminum-honeycomb-sandwich panel absorbed the remainder of the incident heating (0.8 Btu/sq ft-sec). The panel successfully withstood (1) 46.7 hr of radiant heating which included 53 thermal cycles and 5000 cycles of uniaxial inplane loading of + or - 1200 lfb/in; (2) simulated 2g-maneuver heating conditions and simulated cooling system failures without excessive temperatures on the structural panel; and (3) the extensive thermal/structural tests and the aerothermal tests reported in NASA TP-1595 without significant damage to the structural panel, coolant leaks, or hot-gas ingress to the structural panel.

  5. Flightweight radiantly and actively cooled panel: Thermal and structural performance

    NASA Technical Reports Server (NTRS)

    Shore, C. P.; Nowak, R. J.; Kelly, H. N.

    1982-01-01

    A 2- by 4-ft flightweight panel was subjected to thermal/structural tests representative of design flight conditions for a Mach 6.7 transport and to off-design conditions simulating flight maneuvers and cooling system failures. The panel utilized Rene 41 heat shields backed by a thin layer of insulation to radiate away most of the 12 Btu/ft2-sec incident heating. A solution of ethylene glycol in water circulating through tubes in an aluminum-honeycomb-sandwich panel absorbed the remainder of the incident heating (0.8 Btu/sq ft-sec). The panel successfully withstood (1) 46.7 hr of radiant heating which included 53 thermal cycles and 5000 cycles of uniaxial inplane loading of + or - 1200 lfb/in; (2) simulated 2g-maneuver heating conditions and simulated cooling system failures without excessive temperatures on the structural panel; and (3) the extensive thermal/structural tests and the aerothermal tests reported in NASA TP-1595 without significant damage to the structural panel, coolant leaks, or hot-gas ingress to the structural panel.

  6. High heat flux actively cooled honeycomb sandwich structural panel for a hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Koch, L. C.; Pagel, L. L.

    1978-01-01

    The results of a program to design and fabricate an unshielded actively cooled structural panel for a hypersonic aircraft are presented. The design is an all-aluminum honeycomb sandwich with embedded cooling passages soldered to the inside of the outer moldline skin. The overall finding is that an actively cooled structure appears feasible for application on a hypersonic aircraft, but the fabrication process is complex and some material and manufacturing technology developments are required. Results from the program are summarized and supporting details are presented.

  7. A fuselage/tank structure study for actively cooled hypersonic cruise vehicles: Structural analysis

    NASA Technical Reports Server (NTRS)

    Baker, A. H.

    1975-01-01

    The effects of fuselage cross-section (circular and elliptical) and structural arrangement (integral and nonintegral tanks) on the performance of actively cooled hypersonic cruise vehicles was evaluated. It was found that integrally machined stiffening of the tank walls, while providing the most weight-efficient use of materials, results in higher production costs. Fatigue and fracture mechanics appeared to have little effect on the weight of the three study aircraft. The need for thermal strain relief through insulation is discussed. Aircraft size and magnitude of the internal pressure are seen to be significant factors in tank design.

  8. Design and fabrication of a skin stringer discrete tube actively cooled structural panel

    NASA Technical Reports Server (NTRS)

    Anthony, F. M.

    1978-01-01

    The design optimization and practical implementation of actively cooled structural panel concepts was investigated. The desired actively cooled structural panel consisted of the cooled skin and a substructure. The primary load carrying components were fabricated from 2024-T3 aliminum alloy. The 3003-H14 coolant passage tubing was chosen because of its excellent corrosion resistance, workability needed to obtain the desired cross sectional shape, and strength. The Epon 951 adhesive was selected for its excellent structural properties and is the thinnest of available films, 0.064 mm. The Eccobond 58C silver filled epoxy was chosen because of its high thermal conductivity, and the alumina filled Epon 828 was chosen for structural and expansion characteristics.

  9. Evaluation of a large capacity heat pump concept for active cooling of hypersonic aircraft structure

    NASA Technical Reports Server (NTRS)

    Pagel, L. L.; Herring, R. L.

    1978-01-01

    Results of engineering analyses assessing the conceptual feasibility of a large capacity heat pump for enhancing active cooling of hypersonic aircraft structure are presented. A unique heat pump arrangement which permits cooling the structure of a Mach 6 transport to aluminum temperatures without the aid of thermal shielding is described. The selected concept is compatible with the use of conventional refrigerants, with Freon R-11 selected as the preferred refrigerant. Condenser temperatures were limited to levels compatible with the use of conventional refrigerants by incorporating a unique multipass condenser design, which extracts mechanical energy from the hydrogen fuel, prior to each subsequent pass through the condenser. Results show that it is technically feasible to use a large capacity heat pump in lieu of external shielding. Additional analyses are required to optimally apply this concept.

  10. Design and fabrication of a radiative actively cooled honeycomb sandwich structural panel for a hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Ellis, D. A.; Pagel, L. L.; Schaeffer, D. M.

    1978-01-01

    The panel assembly consisted of an external thermal protection system (metallic heat shields and insulation blankets) and an aluminum honeycomb structure. The structure was cooled to temperature 442K (300 F) by circulating a 60/40 mass solution of ethylene glycol and water through dee shaped coolant tubes nested in the honeycomb and adhesively bonded to the outer skin. Rene'41 heat shields were designed to sustain 5000 cycles of a uniform pressure of + or - 6.89kPa (+ or - 1.0 psi) and aerodynamic heating conditions equivalent to 136 kW sq m (12 Btu sq ft sec) to a 422K (300 F) surface temperature. High temperature flexible insulation blankets were encased in stainless steel foil to protect them from moisture and other potential contaminates. The aluminum actively cooled honeycomb sandwich structural panel was designed to sustain 5000 cycles of cyclic in-plane loading of + or - 210 kN/m (+ or - 1200 lbf/in.) combined with a uniform panel pressure of + or - 6.89 kPa (?1.0 psi).

  11. Study of structural active cooling and heat sink systems for space shuttle

    NASA Technical Reports Server (NTRS)

    1972-01-01

    This technology investigation was conducted to evaluate the feasibility of a number of thermal protection systems (TPS) concepts which are alternate candidates to the space shuttle baseline TPS. Four independent tasks were performed. Task 1 consisted of an in-depth evaluation of active structural cooling of the space shuttle orbiter. In Task 2, heat sink concepts for the booster were studied to identify and postulate solutions for design problems unique to heat sink TPS. Task 3 consisted of a feasibility demonstration test of a phase change material (PCM) incorporated into a reusable surface insulation (RSI) thermal protection system for the shuttle orbiter. In Task 4 the feasibility of heat pipes for stagnation region cooling was studied for the booster and the orbiter. Designs were developed for the orbiter leading edge and used in trade studies of leading edge concepts. At the time this program was initiated, a 2-stage fully reusable shuttle system was envisioned; therefore, the majority of the tasks were focused on the fully reusable system environments. Subsequently, a number of alternate shuttle system approaches, with potential for reduced shuttle system development funding requirements, were proposed. Where practicable, appropriate shifts in emphasis and task scoping were made to reflect these changes.

  12. Elastocaloric cooling: Stretch to actively cool

    NASA Astrophysics Data System (ADS)

    Ossmer, Hinnerk; Kohl, Manfred

    2016-10-01

    The elastocaloric effect can be exploited in solid-state cooling technologies as an alternative to conventional vapour compression. Now, an elastocaloric device based on the concept of active regeneration achieves a temperature lift of 15.3 K and efficiencies competitive with other caloric-based approaches.

  13. Coronal Structures in Cool Stars

    NASA Technical Reports Server (NTRS)

    Oliversen, Ronald (Technical Monitor); Dupree, Andrea K.

    2004-01-01

    Many papers have been published that further elucidate the structure of coronas in cool stars as determined from EUVE, HST, FUSE, Chandra, and XMM-Newton observations. In addition we are exploring the effects of coronas on the He I 1083081 transition that is observed in the infrared. Highlights of these are summarized below including publications during this reporting period and presentations. Ground-based magnetic Doppler imaging of cool stars suggests that active stars have active regions located at high latitudes on their surface. We have performed similar imaging in X-ray to locate the sites of enhanced activity using Chandra spectra. Chandra HETG observations of the bright eclipsing contact binary 44i Boo and Chandra LETG observations for the eclipsing binary VW Cep show X-ray line profiles that are Doppler-shifted by orbital motion. After careful analysis of the spectrum of each binary, a composite line-profile is constructed by adding the individual spectral lines. This high signal-to-noise ratio composite line-profile yields orbital velocities for these binaries that are accurate to 30 km/sec and allows their orbital motion to be studied at higher time resolutions. In conjunction with X-ray lightcurves, the phase-binned composite line-profiles constrain coronal structures to be small and located at high latitudes. These observations and techniques show the power of the Doppler Imaging Technique applied to X-ray line emission.

  14. Cooled Ceramic Matrix Composite Propulsion Structures Demonstrated

    NASA Technical Reports Server (NTRS)

    Jaskowiak, Martha H.; Dickens, Kevin W.

    2005-01-01

    NASA's Next Generation Launch Technology (NGLT) Program has successfully demonstrated cooled ceramic matrix composite (CMC) technology in a scramjet engine test. This demonstration represented the world s largest cooled nonmetallic matrix composite panel fabricated for a scramjet engine and the first cooled nonmetallic composite to be tested in a scramjet facility. Lightweight, high-temperature, actively cooled structures have been identified as a key technology for enabling reliable and low-cost space access. Tradeoff studies have shown this to be the case for a variety of launch platforms, including rockets and hypersonic cruise vehicles. Actively cooled carbon and CMC structures may meet high-performance goals at significantly lower weight, while improving safety by operating with a higher margin between the design temperature and material upper-use temperature. Studies have shown that using actively cooled CMCs can reduce the weight of the cooled flow-path component from 4.5 to 1.6 lb/sq ft and the weight of the propulsion system s cooled surface area by more than 50 percent. This weight savings enables advanced concepts, increased payload, and increased range. The ability of the cooled CMC flow-path components to operate over 1000 F hotter than the state-of-the-art metallic concept adds system design flexibility to space-access vehicle concepts. Other potential system-level benefits include smaller fuel pumps, lower part count, lower cost, and increased operating margin.

  15. Platelet actively cooled thermal management devices

    NASA Astrophysics Data System (ADS)

    Mueggenburg, H. H.; Hidahl, J. W.; Kessler, E. L.; Rousar, D. C.

    1992-07-01

    An overview of 28 years of actively-cooled platelet thermal management devices design and development history is presented. Platelet devices are created by bonding together thin metal sheets (platelets) which contain chemically-etched coolant pasages. The bonding process produces an intricate and precise matrix of coolant passages and structural walls contained within a monolithic structure. Thirteen specific applications for platelet thermal management devices are described. These devices are cooled using convective, film, and transpiration cooling techniques. Platelet thermal management devices have been fabricated from a variety of metals, cooled with a variety of fluids, and operated at heat fluxes up to 200 Btu/sq in.-sec.

  16. Coronal Structures in Cool Stars

    NASA Technical Reports Server (NTRS)

    Oliversen, Ronald (Technical Monitor); Duprec, Andrea K.

    2003-01-01

    Many papers have been published that further elucidate the structure of coronas in cool stars as determined from EUVE, HST, FUSE, Chandra, and XMM-Newton observations. Highlights of these are summarized including publications during this reporting period and presentations.

  17. Coronal Structures In Cool Stars

    NASA Technical Reports Server (NTRS)

    Dupree, Andrea K.; Oliversen, Ronald (Technical Monitor)

    2002-01-01

    Many papers have been published that further elucidate the structure of coronas in cool stars as determined from EUVE, HST, FUSE, Chandra, and XMM-Newton observations. Highlights of these are summarized in several pages folk wing that were presented at, the AAS Meeting in Albuquerque in June 2002 during the Topical Session.

  18. A fuselage/tank structure study for actively cooled hypersonic cruise vehicles, summary. [aircraft design of aircraft fuel systems

    NASA Technical Reports Server (NTRS)

    Pirrello, C. J.; Baker, A. H.; Stone, J. E.

    1976-01-01

    A detailed analytical study was made to investigate the effects of fuselage cross section (circular and elliptical) and the structural arrangement (integral and nonintegral tanks) on aircraft performance. The vehicle was a 200 passenger, liquid hydrogen fueled Mach 6 transport designed to meet a range goal of 9.26 Mn (5000 NM). A variety of trade studies were conducted in the area of configuration arrangement, structural design, and active cooling design in order to maximize the performance of each of three point design aircraft: (1) circular wing-body with nonintegral tanks, (2) circular wing-body with integral tanks and (3) elliptical blended wing-body with integral tanks. Aircraft range and weight were used as the basis for comparison. The resulting design and performance characteristics show that the blended body integral tank aircraft weights the least and has the greatest range capability, however, producibility and maintainability factors favor nonintegral tank concepts.

  19. Experimental investigations on active cooling thermal protection structure of hydrocarbon-fueled scramjet combustor in arc heated facility

    NASA Astrophysics Data System (ADS)

    Jianqiang, Tu; Jinlong, Peng; Xianning, Yang; Lianzhong, Chen

    2016-10-01

    The active cooling thermal protection technology is the efficient method to resolve the long-duration work and reusable problems of hydrocarbon-fueled scramjet combustor, where worst thermo-mechanical loads occur. The fuel is passed through coolant channels adjacent to the heated surfaces to absorb heat from the heating exchanger panels, prior to injection into the combustor. The heating exchanger both cooled down the wall temperature of the combustor wall and heats and cracks the hydrocarbon fuel inside the panel to permit an easier combustion and satisfying combustion efficiency. The subscale active cooling metallic panels, with dimensions of 100×100 mm and different coolant channel sizes, have been tested under typical combustion thermal environment produced by arc heated Turbulent Flow Duct (TFD). The heat exchange ability of different coolant channel sizes has been obtained. The big-scale active cooling metallic panel, with dimensions of 100 × 750 mm and the coolant channel sizes of better heating exchange performance, has been made and tested in the big-scale arc heated TFD facility. The test results show that the local superheated ablation is easy to happen for the cooling fuel assigned asymmetrically in the bigscale active cooling metallic panel, and the cooling fuel rate can reduce 8%˜10% after spraying the Thermal Barrier Coating (TBC) in the heating surface.

  20. Cooled snubber structure for turbine blades

    DOEpatents

    Mayer, Clinton A; Campbell, Christian X; Whalley, Andrew; Marra, John J

    2014-04-01

    A turbine blade assembly in a turbine engine. The turbine blade assembly includes a turbine blade and a first snubber structure. The turbine blade includes an internal cooling passage containing cooling air. The first snubber structure extends outwardly from a sidewall of the turbine blade and includes a hollow interior portion that receives cooling air from the internal cooling passage of the turbine blade.

  1. Coronal Structures in Cool Stars

    NASA Technical Reports Server (NTRS)

    Oliversen, Ronald (Technical Monitor); Dupree, Andrea K.

    2005-01-01

    We have extended our study of the structure of coronas in cool stars to very young stars still accreting from their surrounding disks. In addition we are pursing the connection between coronal X-rays and a powerful diagnostic line in the infrared, the He I 10830Angstrom transition of helium. Highlights of these are summarized below including publications during this reporting period and presentations. Spectroscopy of the infrared He I (lambda10830) line with KECK/NIRSPEC and IRTF/CSHELL and of the ultraviolet C III (lambda977) and O VI (lambda1032) emission with FUSE reveals that the classical T Tauri star TW Hydrae exhibits P Cygni profiles, line asymmetries, and absorption indicative of a continuous, fast (approximately 400 kilometers per second), hot (approximately 300,000 K) accelerating outflow with a mass loss rate approximately 10(exp -11)-10(exp -12) solar mass yr(sup -1) or larger. Spectra of T Tauri N appear consistent with such a wind. The source of the emission and outflow seems restricted to the stars themselves. Although the mass accretion rate is an order of magnitude less for TW Hya than for T Tau, the outflow reaches higher velocities at chromospheric temperatures in TW Hya. Winds from young stellar objects may be substantially hotter and faster than previously thought. The ultraviolet emission lines, when corrected for absorption are broad. Emission associated with the accretion flow and shock is likely to show turbulent broadening. We note that the UV line widths are significantly larger than the X-ray line widths. If the X-rays from TW Hya are generated at the accretion shock, the UV lines may not be directly associated with the shock. On the other hand, studies of X-ray emission in young star clusters, suggest that the strength of the X-ray emission is correlated with stellar rotation, thus casting doubt on an accretion origin for the X-rays. We are beginning to access the infrared spectral region where the He I 108308Angstroms transition

  2. A fuselage/tank structure study for actively cooled hypersonic cruise vehicles: Aircraft design evaluation

    NASA Technical Reports Server (NTRS)

    Nobe, T.

    1975-01-01

    The effects of fuselage cross sections and structural members on the performance of hypersonic cruise aircraft are evaluated. Representative fuselage/tank area structure was analyzed for strength, stability, fatigue and fracture mechanics. Various thermodynamic and structural tradeoffs were conducted to refine the conceptual designs with the primary objective of minimizing weight and maximizing aircraft range.

  3. Performance of brazed graphite, carbon-fiber composite, and TZM materials for actively cooled structures; Qualification tests

    SciTech Connect

    Smid, I. ); Croessmann, C.D.; Watson, R.D. ); Linke, J. ); Cardella, A.; Bolt, H,. ); Reheis, N.; Kny, E. )

    1991-07-01

    The divertor of a near-term fusion device has to withstand high heat fluxes, heat shocks, and erosion caused by the plasma. Furthermore, it has to be maintainable through remote techniques. Above all, a good heat removal capability across the interface (low-Z armor/heat sink) plus overall integrity after many operational cycles are needed. To meet all these requirements, an active metal brazing technique is applied to bond graphite and carbon-fiber composite materials to a heat sink consisting of a Mo-41Re coolant tube through a TZM body. Plain brazed graphite and TZM tiles are tested for their fusion-relevant properties. The interfaces appear undamaged after thermal cycling when the melting point of the braze joint is not exceeded and when the graphite armor is {gt}4 mm thick. High heat flux tests are performed on three actively cooled divertor targets. The braze joints show no sign of failure after exposure to thermal loads {approximately}25% higher than the design value surface heat flux of 10 MW/m{sup 2}.

  4. Active cooling from the sixties to NASP

    NASA Technical Reports Server (NTRS)

    Kelly, H. Neale; Blosser, Max L.

    1994-01-01

    Vehicles, such as the X-15 or the National Aerospace Plane (NASP), traveling at hypersonic speeds through the earth's atmosphere experience aerodynamic heating. The heating can be severe enough that a thermal protection system is required to limit the temperature of the vehicle structure. Although several categories of thermal protection systems are mentioned briefly, the majority of the present paper describes convectively cooled structures for large areas. Convective cooling is a method of limiting structural temperatures by circulating a coolant through the vehicle structure. Efforts to develop convectively cooled structures during the past 30 years, from early engine structures which were intended to be tested on the X-15 to structural panels fabricated and tested under the NASP program, are described. Many of the lessons learned from these research efforts are presented.

  5. Active cooling from the sixties to NASP

    NASA Technical Reports Server (NTRS)

    Kelly, H. Neale; Blosser, Max L.

    1992-01-01

    Vehicles, such as the X-15 or National Aero-Space Plane, traveling at hypersonic speeds through the earth's atmosphere experience aerodynamic heating. The heating can be severe enough that a thermal protection system is required to limit the temperature of the vehicle structure. Although several categories of thermal protection systems are mentioned briefly, the majority of this paper describes convectively cooled structures for large areas. Convective cooling is a method of limiting structural temperatures by circulating a coolant through the vehicle structure. Efforts to develop convectively cooled structures during the past 30 years--from early engine structures, which were intended to be tested on the X-15, to structural--are described. Many of the lessons learned from these research efforts are presented.

  6. Chromospheric Activity in Cool Stars: Open Questions

    NASA Astrophysics Data System (ADS)

    Schröder, K.-P.; Schmitt, J. H. M. M.

    2013-04-01

    Despite a wealth of observational insight into chromospheric physics obtained in the past decades, a number of fundamental questions remain to be answered. On some of them we seem to make progress, others are motivation for ongoing research: is there a well-defined “zero-point” of magnetic stellar activity, and by which heating processes is the basal chromospheric flux created? Or: how did the Sun look like during the Maunder Minimum, and when is the next one due? And are activity cycles of cool giants caused by a solar-type dynamo, despite a very different internal structure? What makes magnetic stellar activity be still (or again?) at work in such very evolved stars — should not all angular momentum have been consumed? To find some answers, the Hamburg Robotic Telescope, equipped with a high-resolution (20,000) spectrograph, will start regular operation at its final site in Guanajuato, central Mexico, this year (2012), in part to resume the legendary Mt. Wilson stellar activity monitoring project.

  7. Modeling active galactic nucleus feedback in cool-core clusters: The balance between heating and cooling

    SciTech Connect

    Li, Yuan; Bryan, Greg L.

    2014-07-01

    We study the long-term evolution of an idealized cool-core galaxy cluster under the influence of momentum-driven active galactic nucleus (AGN) feedback using three-dimensional high-resolution (60 pc) adaptive mesh refinement simulations. The feedback is modeled with a pair of precessing jets whose power is calculated based on the accretion rate of the cold gas surrounding the supermassive black hole (SMBH). The intracluster medium first cools into clumps along the propagation direction of the jets. As the jet power increases, gas condensation occurs isotropically, forming spatially extended structures that resemble the observed Hα filaments in Perseus and many other cool-core clusters. Jet heating elevates the gas entropy, halting clump formation. The cold gas that is not accreted onto the SMBH settles into a rotating disk of ∼10{sup 11} M {sub ☉}. The hot gas cools directly onto the disk while the SMBH accretes from its innermost region, powering the AGN that maintains a thermally balanced state for a few Gyr. The mass cooling rate averaged over 7 Gyr is ∼30 M {sub ☉} yr{sup –1}, an order of magnitude lower than the classic cooling flow value. Medium resolution simulations produce similar results, while in low resolution runs, the cluster experiences cycles of gas condensation and AGN outbursts. Owing to its self-regulating mechanism, AGN feedback can successfully balance cooling with a wide range of model parameters. Our model also produces cold structures in early stages that are in good agreement with the observations. However, the long-lived massive cold disk is unrealistic, suggesting that additional physical processes are still needed.

  8. 40 CFR 401.14 - Cooling water intake structures.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 30 2013-07-01 2012-07-01 true Cooling water intake structures. 401.14... AND STANDARDS GENERAL PROVISIONS § 401.14 Cooling water intake structures. The location, design, construction and capacity of cooling water intake structures of any point source for which a standard...

  9. 40 CFR 401.14 - Cooling water intake structures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 30 2012-07-01 2012-07-01 false Cooling water intake structures. 401... GUIDELINES AND STANDARDS GENERAL PROVISIONS § 401.14 Cooling water intake structures. The location, design, construction and capacity of cooling water intake structures of any point source for which a standard...

  10. 40 CFR 401.14 - Cooling water intake structures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Cooling water intake structures. 401.14... AND STANDARDS GENERAL PROVISIONS § 401.14 Cooling water intake structures. The location, design, construction and capacity of cooling water intake structures of any point source for which a standard...

  11. 40 CFR 401.14 - Cooling water intake structures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 29 2011-07-01 2009-07-01 true Cooling water intake structures. 401.14... AND STANDARDS GENERAL PROVISIONS § 401.14 Cooling water intake structures. The location, design, construction and capacity of cooling water intake structures of any point source for which a standard...

  12. 40 CFR 401.14 - Cooling water intake structures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 29 2014-07-01 2012-07-01 true Cooling water intake structures. 401.14... AND STANDARDS GENERAL PROVISIONS § 401.14 Cooling water intake structures. The location, design, construction and capacity of cooling water intake structures of any point source for which a standard...

  13. PCM Passive Cooling System Containing Active Subsystems

    NASA Technical Reports Server (NTRS)

    Blanding, David E.; Bass, David I.

    2005-01-01

    A multistage system has been proposed for cooling a circulating fluid that is subject to intermittent intense heating. The system would be both flexible and redundant in that it could operate in a basic passive mode, either sequentially or simultaneously with operation of a first, active cooling subsystem, and either sequentially or simultaneously with a second cooling subsystem that could be active, passive, or a combination of both. This flexibility and redundancy, in combination with the passive nature of at least one of the modes of operation, would make the system more reliable, relative to a conventional cooling system. The system would include a tube-in-shell heat exchanger, within which the space between the tubes would be filled with a phase-change material (PCM). The circulating hot fluid would flow along the tubes in the heat exchanger. In the basic passive mode of operation, heat would be conducted from the hot fluid into the PCM, wherein the heat would be stored temporarily by virtue of the phase change.

  14. Activation of a new cooling tower facility

    SciTech Connect

    Lansford, W.D.

    1986-01-01

    The activation of a completely new facility presents problems not found in modifications or additions to existing systems. Known baselines of previous operations provide some guidelines as to what is causing a particular problem. However, when a totally new, complex facility initially becomes operational, unfamiliar instrumentation, mechanical equipment, and unknown system idiosyncrasies, require careful analysis of each event to determine whether one is observing a symptom of pending disaster or a minor isolated occurrence of some subsystem. Careful planning and progressive introduction of related systems must be initiated, introducing operating personnel into the chain of events as early as possible. Personnel responsible for operation and maintenance should participate in the review of initial concepts and designs, to provide input based on systems experience. The cooling tower system described in this paper has gained recognition for dependability and consistency of operations since initially becoming operational. Instead of a once weekly activity, as originally anticipated, test units are now requesting cooling tower support for all test operations. During one five-month period, a total of 660 cooling tower operating hours were logged with one test support period of 78 non-stop hours recorded. The use of the cooling tower beyond original expectations is a compliment without comparison.

  15. Design and evaluation of active cooling systems for Mach 6 cruise vehicle wings

    NASA Technical Reports Server (NTRS)

    Mcconarty, W. A.; Anthony, F. M.

    1971-01-01

    Active cooling systems, which included transpiration, film, and convective cooling concepts, are examined. Coolants included hydrogen, helium, air, and water. Heat shields, radiation barriers, and thermal insulation are considered to reduce heat flow to the cooling systems. Wing sweep angles are varied from 0 deg to 75 deg and wing leading edge radii of 0.05 inch and 2.0 inches are examined. Structural temperatures are varied to allow comparison of aluminum alloy, titanium alloy, and superalloy structural materials. Cooled wing concepts are compared among themselves, and with the uncooled concept on the basis of structural weight, cooling system weight, and coolant weight.

  16. Advanced fabrication techniques for cooled engine structures

    NASA Technical Reports Server (NTRS)

    Buchmann, O. A.

    1978-01-01

    An improved design for regeneratively cooled engine structures was identified. This design uses photochemically machined (PCM) coolant passages. It permits the braze joint to be placed in a relatively cool area, remote from the critical hot face sheet. The geometry of the passages at the face sheet also minimizes stress concentration and, therefore, enhances the low cycle fatigue performance. The two most promising alloys identified for this application are Inconel 617 and Nickel 201. Inconel 617 was selected because it has excellent creep rupture properties, while Nickel 201 was selected because of its predicted good performance under low cycle fatigue loading. The fabrication of the PCM coolant passages in both Inconel 617 and Nickel 201 was successfully developed. During fabrication of Inconel 617, undesirable characteristics were observed in the braze joints. A development program to resolve this condition was undertaken and led to definition of an isothermal solidification process for joining Inconel 617 panels. This process produced joints which approach parent metal strength and homogeneity.

  17. Physical Properties of Cooling Plasma in Quiescent Active Region Loops

    NASA Astrophysics Data System (ADS)

    Landi, E.; Miralles, M. P.; Curdt, W.; Hara, H.

    2009-04-01

    In the present work, we use SOHO/SUMER, SOHO/UVCS, SOHO/EIT, SOHO/LASCO, STEREO/EUVI, and Hinode/EIS coordinated observations of an active region (AR 10989) at the west limb taken on 2008 April 8 to study the cooling of coronal loops. The cooling plasma is identified using the intensities of SUMER spectral lines emitted at temperatures in the 4.15 <= log T <= 5.45 range. EIS and SUMER spectral observations are used to measure the physical properties of the loops. We found that before cooling took place these loops were filled with coronal hole-like plasma, with temperatures in the 5.6 <= log T <= 5.9 range. SUMER spectra also allowed us to determine the plasma temperature, density, emission measure, element abundances, and dynamic status during the cooling process. The ability of EUVI to observe the emitting region from a different direction allowed us to measure the volume of the emitting region and estimate its emission measure. Comparison with values measured from line intensities provided us with an estimate of the filling factor. UVCS observations of the coronal emission above the active region showed no streamer structure associated with AR 10989 at position angles between 242°and 253fdg EIT, LASCO, and EUVI-A narrowband images and UVCS spectral observations were used to discriminate between different scenarios and monitor the behavior of the active region in time. The present study provides the first detailed measurements of the physical properties of cooling loops, a very important benchmark for theoretical models of loop cooling and condensation.

  18. Protection of cooled blades of complex internal structure

    NASA Technical Reports Server (NTRS)

    Glamiche, P.

    1977-01-01

    The problem of general protection of cooled blades of complex internal structure was solved by a method called SF technique which makes possible the protection of both external and internal surfaces, as well as those of the orifices of cooling air, whatever their diameter. The SF method is most often applied in the case of pack process, at controlled or high activity; it can be of use on previously uncoated parts, but also on pieces already coated by a thermochemical, chemical or PVD method. The respective thickness of external and internal coatings may be precisely predetermined, no parasitic particle being liable to remain inside the parts after application of the protecting treatment. Results obtained to date by application of this method are illustrated by the presentation and examination of a various selection of advanced turbo engines.

  19. Active and passive cooling for concentrating photovoltaic arrays

    SciTech Connect

    Edenburn, M.W.

    1981-10-01

    Optimization, based on minimum energy cost, of active and passive cooling designs for point-focus Fresnel lens photovoltaic arrays and line-focus, parabolic-trough photovoltaic arrays is discussed, and the two types of cooling are compared. Passive cooling is more cost-effective for Fresnel lens arrays while the reverse is true for parabolic-trough arrays.

  20. Two stage serial impingement cooling for isogrid structures

    SciTech Connect

    Lee, Ching-Pang; Morrison, Jay A.

    2014-09-09

    A system for cooling a wall (24) of a component having an outer surface with raised ribs (12) defining a structural pocket (10), including: an inner wall (26) within the structural pocket and separating the wall outer surface within the pocket into a first region (28) outside of the inner wall and a second region (40) enclosed by the inner wall; a plate (14) disposed atop the raised ribs and enclosing the structural pocket, the plate having a plate impingement hole (16) to direct cooling air onto an impingement cooled area (38) of the first region; a cap having a skirt (50) in contact with the inner wall, the cap having a cap impingement hole (20) configured to direct the cooling air onto an impingement cooled area (44) of the second region, and; a film cooling hole (22) formed through the wall in the second region.

  1. Annual DOE Active Solar Heating and Cooling Contractors Review meeting

    NASA Astrophysics Data System (ADS)

    1981-09-01

    Ninety three project summaries dicussing the following aspects of active solar heating and cooling are presented: Rankine solar cooling systems; absorption solar cooling systems; desiccant solar cooling systems; solar heat pump systems; solar hot water systems; special projects (such as the National Solar Data Network, hybrid solar thermal/photovoltaic applications, and heat transfer and water migration in soils); administrative/management support; and solar collector, storage, controls, analysis, and materials technology.

  2. Actively controlling coolant-cooled cold plate configuration

    DOEpatents

    Chainer, Timothy J.; Parida, Pritish R.

    2016-04-26

    Cooling apparatuses are provided to facilitate active control of thermal and fluid dynamic performance of a coolant-cooled cold plate. The cooling apparatus includes the cold plate and a controller. The cold plate couples to one or more electronic components to be cooled, and includes an adjustable physical configuration. The controller dynamically varies the adjustable physical configuration of the cold plate based on a monitored variable associated with the cold plate or the electronic component(s) being cooled by the cold plate. By dynamically varying the physical configuration, the thermal and fluid dynamic performance of the cold plate are adjusted to, for example, optimally cool the electronic component(s), and at the same time, reduce cooling power consumption used in cooling the electronic component(s). The physical configuration can be adjusted by providing one or more adjustable plates within the cold plate, the positioning of which may be adjusted based on the monitored variable.

  3. The Design of Actively Cooled Plasma-Facing Components

    NASA Astrophysics Data System (ADS)

    Scheerer, M.; Bolt, H.; Gervash, A.; Linke, J.; Smid, I.

    In future fusion devices, like in the stellarator Wendelstein 7-X, the target plates of the divertor will be exposed to heat loads up to power densities of 10 MW/m2 for 1000 s. For this purpose actively cooled target elements with an internal coolant flow return, made of 2-D CFC armor tiles brazed onto a two tube cooling structure were developed and manufactured at the Forschungszentrum Jülich. Individual bent- and coolant flow reversal elements were used to achieve a high flexibility in the shape of the target elements. A special brazing technology, using a thin layer of plasma-arc deposited titanium was used for the bonding of the cooling structure to the plasma facing armor (PFA). FEM-simulations of the thermal and mechanical behavior show that a detachment of about 25% of the bonded area between the copper tubes and the PFA can be tolerated, without exceeding the critical heat flux at 15 MW/m2 or a surface temperature of 1400°C at 10 MW/m2 by using twisted tape inserts with a twist ratio of 2 at a cooling water velocity of 10 m/s. Thermal cycling tests in an electron beam facility up to a power density level 10.5 MW/m2 show a very good behavior of parts of the target elements, which confirms the performance under fusion relevant conditions. Even defected parts in the bonding interface of the target elements, known from ultrasonic inspections before, show no change in the thermal performance under cycling, which confirms also the structural integrity of partly defected regions.

  4. Active and passive cooling for concentrating photovoltaic arrays

    SciTech Connect

    Edenburn, M.W.

    1980-01-01

    The optimization, based on minimum energy cost, of active and passive cooling designs for point-focus Fresnel lens photovoltaic arrays and line-focus, parabolic-trough photovoltaic arrays are discussed, and the two types of cooling are compared. Passive cooling is more cost effective than active for Fresnel lens arrays while the reverse is true for parabolic trough arrays. The analysis produced several other conclusions of interest which are also discussed.

  5. Natural circulating passive cooling system for nuclear reactor containment structure

    DOEpatents

    Gou, Perng-Fei; Wade, Gentry E.

    1990-01-01

    A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

  6. Passive cooling system for nuclear reactor containment structure

    DOEpatents

    Gou, Perng-Fei; Wade, Gentry E.

    1989-01-01

    A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

  7. Thermal transfer structures coupling electronics card(s) to coolant-cooled structure(s)

    DOEpatents

    David, Milnes P; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Parida, Pritish R; Schmidt, Roger R

    2014-12-16

    Cooling apparatuses and coolant-cooled electronic systems are provided which include thermal transfer structures configured to engage with a spring force one or more electronics cards with docking of the electronics card(s) within a respective socket(s) of the electronic system. A thermal transfer structure of the cooling apparatus includes a thermal spreader having a first thermal conduction surface, and a thermally conductive spring assembly coupled to the conduction surface of the thermal spreader and positioned and configured to reside between and physically couple a first surface of an electronics card to the first surface of the thermal spreader with docking of the electronics card within a socket of the electronic system. The thermal transfer structure is, in one embodiment, metallurgically bonded to a coolant-cooled structure and facilitates transfer of heat from the electronics card to coolant flowing through the coolant-cooled structure.

  8. Actively controlling coolant-cooled cold plate configuration

    SciTech Connect

    Chainer, Timothy J.; Parida, Pritish R.

    2015-07-28

    A method is provided to facilitate active control of thermal and fluid dynamic performance of a coolant-cooled cold plate. The method includes: monitoring a variable associated with at least one of the coolant-cooled cold plate or one or more electronic components being cooled by the cold plate; and dynamically varying, based on the monitored variable, a physical configuration of the cold plate. By dynamically varying the physical configuration, the thermal and fluid dynamic performance of the cold plate are adjusted to, for example, optimally cool the one or more electronic components, and at the same time, reduce cooling power consumption used in cooling the electronic component(s). The physical configuration can be adjusted by providing one or more adjustable plates within the coolant-cooled cold plate, the positioning of which may be adjusted based on the monitored variable.

  9. Evaluation by Rocket Combustor of C/C Composite Cooled Structure Using Metallic Cooling Tubes

    NASA Astrophysics Data System (ADS)

    Takegoshi, Masao; Ono, Fumiei; Ueda, Shuichi; Saito, Toshihito; Hayasaka, Osamu

    In this study, the cooling performance of a C/C composite material structure with metallic cooling tubes fixed by elastic force without chemical bonding was evaluated experimentally using combustion gas in a rocket combustor. The C/C composite chamber was covered by a stainless steel outer shell to maintain its airtightness. Gaseous hydrogen as a fuel and gaseous oxygen as an oxidizer were used for the heating test. The surface of these C/C composites was maintained below 1500 K when the combustion gas temperature was about 2800 K and the heat flux to the combustion chamber wall was about 9 MW/m2. No thermal damage was observed on the stainless steel tubes that were in contact with the C/C composite materials. The results of the heating test showed that such a metallic tube-cooled C/C composite structure is able to control the surface temperature as a cooling structure (also as a heat exchanger) as well as indicated the possibility of reducing the amount of coolant even if the thermal load to the engine is high. Thus, application of this metallic tube-cooled C/C composite structure to reusable engines such as a rocket-ramjet combined-cycle engine is expected.

  10. Active feedback cooling of massive electromechanical quartz resonators

    SciTech Connect

    Jahng, Junghoon; Lee, Manhee; Stambaugh, Corey; Bak, Wan; Jhe, Wonho

    2011-08-15

    We present a general active feedback cooling scheme for massive electromechanical quartz resonators. We cool down two kinds of macrosized quartz tuning forks and find several characteristic constants for this massive quartz-resonator feedback cooling, in good agreement with theoretical calculations. When combined with conventional cryogenic techniques and low-noise devices, one may reach the quantum sensitivity for macroscopic sensors. This may be useful for high sensitivity measurements and for quantum information studies.

  11. Study of active cooling for supersonic transports

    NASA Technical Reports Server (NTRS)

    Brewer, G. D.; Morris, R. E.

    1975-01-01

    The potential benefits of using the fuel heat sink of hydrogen fueled supersonic transports for cooling large portions of the aircraft wing and fuselage are examined. The heat transfer would be accomplished by using an intermediate fluid such as an ethylene glycol-water solution. Some of the advantages of the system are: (1) reduced costs by using aluminum in place of titanium, (2) reduced cabin heat loads, and (3) more favorable environmental conditions for the aircraft systems. A liquid hydrogen fueled, Mach 2.7 supersonic transport aircraft design was used for the reference uncooled vehicle. The cooled aircraft designs were analyzed to determine their heat sink capability, the extent and location of feasible cooled surfaces, and the coolant passage size and spacing.

  12. Active skin cooling in conjunction with laser dermatologic surgery.

    PubMed

    Nelson, J S; Majaron, B; Kelly, K M

    2000-12-01

    The clinical objective in the laser treatment of patients with specific dermatoses is to maximize thermal damage to the target chromophore while minimizing injury to the normal skin. Unfortunately, for some lesions, the threshold incident light dosage for epidermal injury can be very close to the threshold for permanent removal of the target chromophore, thus precluding the use of higher light dosages. An important method of overcoming the aforementioned problem is to selectively cool the most superficial layers of the skin. Although melanin absorption will result in heat production during laser exposure, cooling the epidermis can prevent its temperature elevation from exceeding the threshold for thermal injury. Spatially selective cooling can be achieved by active cooling using a cryogen spray or cold sapphire contact handpieces. These devices promote rapid and spatially selective epidermal cooling to low temperatures without affecting the target chromophore temperature before the laser pulse is delivered. Cooling has become an Integral part in the emerging discipline of laser dermatologic surgery. Attend almost any academic dermatology conference and you are likely to find many lectures that relate to cooling during dermatologic laser surgery. Although cooling in conjunction with laser therapy has become the clinical standard for many laser procedures, considerable controversy surrounds this methodology. We present herewith an overview of currently used techniques for active cooling of human skin and explore their advantages and disadvantages in relationship to specific dermatoses amenable to laser therapy.

  13. Modeling a Transient Pressurization with Active Cooling Sizing Tool

    NASA Technical Reports Server (NTRS)

    Guzik, Monica C.; Plachta, David W.; Elchert, Justin P.

    2011-01-01

    As interest in the area of in-space zero boil-off cryogenic propellant storage develops, the need to visualize and quantify cryogen behavior during ventless tank self-pressurization and subsequent cool-down with active thermal control has become apparent. During the course of a mission, such as the launch ascent phase, there are periods that power to the active cooling system will be unavailable. In addition, because it is not feasible to install vacuum jackets on large propellant tanks, as is typically done for in-space cryogenic applications for science payloads, instances like the launch ascent heating phase are important to study. Numerous efforts have been made to characterize cryogenic tank pressurization during ventless cryogen storage without active cooling, but few tools exist to model this behavior in a user-friendly environment for general use, and none exist that quantify the marginal active cooling system size needed for power down periods to manage tank pressure response once active cooling is resumed. This paper describes the Transient pressurization with Active Cooling Tool (TACT), which is based on a ventless three-lump homogeneous thermodynamic self-pressurization model1 coupled with an active cooling system estimator. TACT has been designed to estimate the pressurization of a heated but unvented cryogenic tank, assuming an unavailable power period followed by a given cryocooler heat removal rate. By receiving input data on the tank material and geometry, propellant initial conditions, and passive and transient heating rates, a pressurization and recovery profile can be found, which establishes the time needed to return to a designated pressure. This provides the ability to understand the effect that launch ascent and unpowered mission segments have on the size of an active cooling system. A sample of the trends found show that an active cooling system sized for twice the steady state heating rate would results in a reasonable time for tank

  14. Cooling rate effects on structure of amorphous graphene

    NASA Astrophysics Data System (ADS)

    Van Hoang, Vo

    2015-01-01

    Simple monatomic amorphous 2D models with Honeycomb structure are obtained from 2D simple monatomic liquids with Honeycomb interaction potential (Rechtsman et al., Phys. Rev. Lett. 95, 228301 (2005)) via molecular dynamics (MD) simulations. Models are observed by cooling from the melt at various cooling rates. Temperature dependence of thermodynamic and structural properties including total energy, mean ring size, mean coordination number is studied in order to show evolution of structure and thermodynamics upon cooling from the melt. Structural properties of the amorphous Honeycomb structures are studied via radial distribution function (RDF), coordination number and ring distributions together with 2D visualization of the atomic configurations. Amorphous Honeycomb structures contain a large amount of structural defects including new ones which have not been previously reported yet. Cooling rate dependence of structural properties of the obtained amorphous Honeycomb structures is analyzed. Although amorphous graphene has been proposed theoretically and/or recently obtained by the experiments, our understanding of structural properties of the system is still poor. Therefore, our simulations highlight the situation and give deeper understanding of structure and thermodynamics of the glassy state of this novel 2D material.

  15. Bacterial community structure in cooling water and biofilm in an industrial recirculating cooling water system.

    PubMed

    Wang, Jinmei; Liu, Min; Xiao, Huijie; Wu, Wei; Xie, Meijuan; Sun, Mengjia; Zhu, Chenglin; Li, Pengfu

    2013-01-01

    Microbial fouling is a serious problem in open recirculating cooling water systems. The bacterial communities that cause it have not been fully understood. In this study, we analyzed the community structure of free-living bacteria and particle-attached bacteria in cooling water, and bacteria in biofilm collected from the wall of the water reservoir in an industrial recirculating cooling water system by construction of a 16S rRNA gene clone library. Based on amplified ribosomal DNA restriction analysis, clones of all three libraries were clustered into 45 operational taxonomic units (OTUs). Thirteen OTUs displaying 91-96% sequence similarity to a type strain might be novel bacterial species. Noted differences in community structure were observed among the three libraries. The relative species richness of the free-living bacteria in cooling water was much lower than that of particle-attached bacteria and bacteria in biofilm. The majority of the free-living bacterial community (99.0%) was Betaproteobacteria. The predominant bacteria in the particle-attached bacterial community were Alphaproteobacteria (20.5%), Betaproteobacteria (27.8%) and Planctomycetes (42.0%), while those in the biofilm bacterial community were Alphaproteobacteria (47.9%), Betaproteobacteria (11.7%), Acidobacteria (13.1%) and Gemmatimonadetes (11.3%). To control microbial fouling in industrial recirculating cooling water systems, additional physiological and ecological studies of these species will be essential.

  16. Structural Assembly for Cold Plate Cooling

    NASA Technical Reports Server (NTRS)

    Zaffetti, Mark A. (Inventor); Taddey, Edmund P. (Inventor)

    2014-01-01

    A device including a structural member having a heat spreader and an electronic device mounted directly to a first surface of the heat spreader of the structural member. The device also includes a cold plate mounted directly to the first surface of the heat spreader of the structural member.

  17. Ptah-socar fuel-cooled composite materials structure

    NASA Astrophysics Data System (ADS)

    Bouchez, M.; Beyer, S.

    2009-09-01

    One of the key points for the development of dual-mode ramjets operating up to Mach 8 or more is the mastery of fuel-cooled composite materials structures, which are needed, at least, for the combustion chamber. MBDA France and EADS ST have been working on the development of a particular technology for such structures taking advantage of the background of MBDA France in the field of dual-mode ramjet and fuel-cooled structures and of ASTRIUM-EADS ST in the field of high-temperature composite materials. They have developed an innovative technology for advanced monobloc cooled C/C/SiC structures. The paper gives an updated status of the development of Paroi Tissée Application Hypersonique - Simple Operational Composite for Advanced Ramjet (PTAH-SOCAR) technology, including test results, and presents some results obtained during system and demonstrator studies.

  18. Preliminary design activities for solar heating and cooling systems

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Information on the development of solar heating and cooling systems is presented. The major emphasis is placed on program organization, system size definition, site identification, system approaches, heat pump and equipment design, collector procurement, and other preliminary design activities.

  19. Active cooling requirements for propellant storage

    NASA Technical Reports Server (NTRS)

    Klein, G. A.

    1984-01-01

    Recent NASA and DOD mission models have indicated future needs for orbital cryogenic storage and supply systems. Two thermal control systems which show the greatest promise for improving propellant storage life were evaluated. One system was an open cycle thermodynamic vent type with a refrigeration system for partial hydrogen reliquefaction located at the LH2 tank and a vapor cooled shield for integrated and non-integrated tank designs to reduce boiloff. The other was a closed system with direct refrigeration at the LH2 tank. A reversed Brayton cycle unit was baselined for the propellant processor. It is concluded that: (1) reliquefaction systems are not attractive for minimizing propellant boiloff; (2) open cycle systems may not be economically attractive for long term storage; (3) a number of refrigeration systems are available to assist in the long term storage of cryogenic propellants; and (4) shields can significantly improve the performance of mechanical coolers.

  20. The Influence of Molecular Cooling in Pregalactic Structure Formation

    NASA Astrophysics Data System (ADS)

    Stancil, P. C.; Abel, T.; Lepp, S.; Dalgarno, A.

    1999-12-01

    The detailed chemistry and cooling in collapsing primordial clouds will be presented for total baryonic densities up to 106 cm-3. The model consists of 160 reactions of 23 species including H2, HD, HeH+, and LiH, and accounts for 8 different cooling and heating mechanisms. The hydrodynamic evolution of the gas is modeled under the assumptions of free-fall, isothermal, and isobaric collapse as well as for the central regions of 105 M⊙ objects in hierarchical scenarios. The latter being drawn from three-dimensional cosmological hydrodynamical simulations. The dominant processes in the reaction network are identified and a minimal model that accurately predicts the full chemistry will be presented. It is found that radiative cooling due to collisional excitation of HD can lower the temperature in a primordial cloud below that reachable through H2 cooling alone. Further, the temperature evolution is influenced by the choice of the adopted H2 radiative cooling function. Implications for globular cluster and primordial star formation, as well as structure formation on small scales and the importance of molecular cooling in general will be discussed. The work of P.C.S. was supported by the DoE ORNL LDRD Seed Money Fund. T.A. acknowledges support from NSF Grant ASC--9318185. The work of S.L. and A.D. was supported by NSF Cooperative Agreement OSR-9353227 and Astronomical Sciences Grant AST-93-01099, respectively.

  1. Thermal and structural tests of a hydrogen cooled panel

    NASA Technical Reports Server (NTRS)

    Richard, C. E.; Duncan, J. D.; Gellersen, E. W.; Demogenes, C.

    1972-01-01

    An experimental evaluation of the thermal and structural performance of a hydrogen-cooled panel is presented. The panel, which was of brazed Inconel 625 and Inconel 718 construction, was designed for a heat flux of 100 BTU per second-foot squared and an external surface pressure of 100 psi.

  2. The structure, energy balance, and winds of cool stars

    NASA Technical Reports Server (NTRS)

    Linsky, J. L.

    1982-01-01

    Solar magnetic field phenomena which occur in cool stars are summarized. Factors which can produce magnetic fields in stars are listed. Information on cool star atmospheres, provided by high dispersion spectra, is discussed. These spectra show that in Beta Dra (G2 Ib) the transition lines are red shifted (an antiwind), perhaps indicating downflows in closed magnetic flux tubes, as seen in the solar flux tubes above sunspots. The G and K giants and supergiants are classed as active, quiet, or hybrid, depending on whether their atmospheres are dominated by closed magnetic flux tubes, open field geometries, or a predominantly open geometry with a few closed flux tubes embedded.

  3. ACUTE CARDIOVASCULAR EFFECTS OF FIREFIGHTING AND ACTIVE COOLING DURING REHABILITATION

    PubMed Central

    Burgess, Jefferey L.; Duncan, Michael D.; Hu, Chengcheng; Littau, Sally R.; Caseman, Delayne; Kurzius-Spencer, Margaret; Davis-Gorman, Grace; McDonagh, Paul F.

    2012-01-01

    Objectives To determine the cardiovascular and hemostatic effects of fire suppression and post-exposure active cooling. Methods Forty-four firefighters were evaluated prior to and after a 12 minute live-fire drill. Next, 50 firefighters undergoing the same drill were randomized to post-fire forearm immersion in 10°C water or standard rehabilitation. Results In the first study, heart rate and core body temperature increased and serum C-reactive protein decreased but there were no significant changes in fibrinogen, sE-selectin or sL-selectin. The second study demonstrated an increase in blood coagulability, leukocyte count, factors VIII and X, cortisol and glucose, and a decrease in plasminogen and sP-selectin. Active cooling reduced mean core temperature, heart rate and leukocyte count. Conclusions Live-fire exposure increased core temperature, heart rate, coagulability and leukocyte count; all except coagulability were reduced by active cooling. PMID:23090161

  4. Physiologic Responses Produced by Active and Passive Personal Cooling Vests

    NASA Technical Reports Server (NTRS)

    Ku, Yu-Tsuan E.; Lee, Hank C.; Montgomery, Leslie D.; Luna, Bernadette

    2000-01-01

    Personal thermoregulatory systems which provide chest cooling are used in the industrial and aerospace environments to alleviate thermal stress. However, little information is available regarding the physiologic and circulatory changes produced by routine operation of these systems. The objectives of this study were to document and compare the subjects' response to three cooling vests in their recommended configurations. The Life Enhancement Tech (LET) lightweight active cooling vest with cap, the MicroClimate Systems Change of Phase garment (MCS), and the Steele Vest were each used to cool the chest regions of 12 male and 8 female Healthy subjects (21 to 69 yr.) in this study. The subjects, seated in an upright position at normal room temperature (approx. 22 C), were tested for 60 min. with one of the cooling garments. The LET active garment had an initial coolant fluid inlet temperature of 60 F, and was ramped down to 50 F. Oral, right and left ear canal temperatures were logged manually every 5 min. Arm, leg, chest and rectal temperatures; heart rate; and respiration were recorded continuously on a U.F.I., Inc. Biolog ambulatory monitor. For men, all three vests had similar, significant cooling effects. Decreases in the average rectal temperature, oral temperature, and ear canal temperatures were approximately 0.2 C, 0.2 C and 0.1 C, respectively. In contrast to the men, the female subjects wearing the MCS and Steel vests had similar cooling responses in which the core temperature remained elevated and oral and ear canal temperatures did not drop. The LET active garment cooled most of the female subjects in this study; rectal, oral and ear temperature decreased about 0.2 C, 0.3 C and 0.3 C, respectively. These results show that the garment configurations tested do not elicit a similar thermal response in all subjects. A gender difference is evident. The LET active garment configuration was most effective in decreasing temperatures of the female subjects; the MCS

  5. Fail-safe system for activity cooled supersonic and hypersonic aircraft. [using liquid hydrogen fuel

    NASA Technical Reports Server (NTRS)

    Jones, R. A.; Braswell, D. O.; Richie, C. B.

    1975-01-01

    A fail-safe-system concept was studied as an alternative to a redundant active cooling system for supersonic and hypersonic aircraft which use the heat sink of liquid-hydrogen fuel for cooling the aircraft structure. This concept consists of an abort maneuver by the aircraft and a passive thermal protection system (TPS) for the aircraft skin. The abort manuever provides a low-heat-load descent from normal cruise speed to a lower speed at which cooling is unnecessary, and the passive TPS allows the aircraft skin to absorb the abort heat load without exceeding critical skin temperature. On the basis of results obtained, it appears that this fail-safe-system concept warrants further consideration, inasmuch as a fail-safe system could possibly replace a redundant active cooling system with no increase in weight and would offer other potential advantages.

  6. Comparison of active cooling devices to passive cooling for rehabilitation of firefighters performing exercise in thermal protective clothing: A report from the Fireground Rehab Evaluation (FIRE) trial

    PubMed Central

    Hostler, David; Reis, Steven E; Bednez, James C; Kerin, Sarah; Suyama, Joe

    2010-01-01

    Background Thermal protective clothing (TPC) worn by firefighters provides considerable protection from the external environment during structural fire suppression. However, TPC is associated with physiological derangements that may have adverse cardiovascular consequences. These derangements should be treated during on-scene rehabilitation periods. Objective The present study examined heart rate and core temperature responses during the application of four active cooling devices, currently being marketed to the fire service for on-scene rehab, and compared them to passive cooling in a moderate temperature (approximately 24°C) and to an infusion of cold (4°C) saline. Methods Subjects exercised in TPC in a heated room. Following an initial exercise period (BOUT 1) the subjects exited the room, removed TPC, and for 20 minutes cooled passively at room temperature, received an infusion of cold normal saline, or were cooled by one of four devices (fan, forearm immersion in water, hand cooling, water perfused cooling vest). After cooling, subjects donned TPC and entered the heated room for another 50-minute exercise period (BOUT 2). Results Subjects were not able to fully recover core temperature during a 20-minute rehab period when provided rehydration and the opportunity to completely remove TPC. Exercise duration was shorter during BOUT 2 when compared to BOUT 1 but did not differ by cooling intervention. The overall magnitude and rate of cooling and heart rate recovery did not differ by intervention. Conclusions No clear advantage was identified when active cooling devices and cold intravenous saline were compared to passive cooling in a moderate temperature after treadmill exercise in TPC. PMID:20397868

  7. Advanced fabrication techniques for hydrogen-cooled engine structures

    NASA Technical Reports Server (NTRS)

    Buchmann, O. A.; Arefian, V. V.; Warren, H. A.; Vuigner, A. A.; Pohlman, M. J.

    1985-01-01

    Described is a program for development of coolant passage geometries, material systems, and joining processes that will produce long-life hydrogen-cooled structures for scramjet applications. Tests were performed to establish basic material properties, and samples constructed and evaluated to substantiate fabrication processes and inspection techniques. Results of the study show that the basic goal of increasing the life of hydrogen-cooled structures two orders of magnitude relative to that of the Hypersonic Research Engine can be reached with available means. Estimated life is 19000 cycles for the channels and 16000 cycles for pin-fin coolant passage configurations using Nickel 201. Additional research is required to establish the fatigue characteristics of dissimilar-metal coolant passages (Nickel 201/Inconel 718) and to investigate the embrittling effects of the hydrogen coolant.

  8. Solid state lighting devices and methods with rotary cooling structures

    DOEpatents

    Koplow, Jeffrey P.

    2017-03-21

    Solid state lighting devices and methods for heat dissipation with rotary cooling structures are described. An example solid state lighting device includes a solid state light source, a rotating heat transfer structure in thermal contact with the solid state light source, and a mounting assembly having a stationary portion. The mounting assembly may be rotatably coupled to the heat transfer structure such that at least a portion of the mounting assembly remains stationary while the heat transfer structure is rotating. Examples of methods for dissipating heat from electrical devices, such as solid state lighting sources are also described. Heat dissipation methods may include providing electrical power to a solid state light source mounted to and in thermal contact with a heat transfer structure, and rotating the heat transfer structure through a surrounding medium.

  9. Actively Cooled SLMS(TM) Technology for HEL Applications

    NASA Technical Reports Server (NTRS)

    Jacoby, Marc T.; Goodman, William A.; Reily, Jack C.; Kegley, Jeffrey R.; Haight, Harlan J.; Tucker, John; Wright, Ernest R.; Hogue, William D.

    2005-01-01

    Mr. Jacoby is the Chief Scientist for Schafer's Lightweight Optical Systems business area with twenty four years experience in laser and optical systems for space and military applications. He and colleague Dr. Goodman conceived and developed Silicon Lightweight Mirrors (SLMS(TM)) technologies for space applications from the extreme UV to FAR IR wavelengths. Schafer has demonstrated two different methods for actively cooling our Silicon Lightweight Mirrors (SLMS(TM)) technology. Direct internal cooling was accomplished by flowing liquid nitrogen through the continuous open cell core of the SLMS(TM) mirror. Indirect external cooling was accomplished by flowing liquid nitrogen through a CTE matched Cesic square-tube manifold that was bonded to the back of the mirror in the center. Testing was done in the small 4-foot thermal/vacuum chamber located at the NASA/MSFC X-Ray Calibration Facility. Seven thermal diodes were located over the front side of the 5 inch diameter mirror and one was placed on the outlet side of the Cesic manifold. Results indicate that the mirror reaches steady state at 82K in less than four minutes for both cooling methods. The maximum temperature difference of the eight diodes was less than 200 mK when the mirror was internally cooled and covered with MLI to insulate it from the large 300 K aluminum plate that was used to mount it.

  10. Study of fail-safe abort system for an actively cooled hypersonic aircraft, volume 2

    NASA Technical Reports Server (NTRS)

    Peeples, M. E.; Herring, R. L.

    1976-01-01

    Conceptual designs of a fail-safe abort system for hydrogen fueled actively cooled high speed aircraft are examined. The fail-safe concept depends on basically three factors: (1) a reliable method of detecting a failure or malfunction in the active cooling system, (2) the optimization of abort trajectories which minimize the descent heat load to the aircraft, and (3) fail-safe thermostructural concepts to minimize both the weight and the maximum temperature the structure will reach during descent. These factors are examined and promising approaches are evaluated based on weight, reliability, ease of manufacture and cost.

  11. UV Observations of Prominence Activation and Cool Loop Dynamics

    NASA Technical Reports Server (NTRS)

    Kucera, Therese A.; Landi, Enrico

    2006-01-01

    In this paper we investigate the thermal and dynamic properties of dynamic structures in and around a prominence channel observed on the limb on 17 April 2003. Observations were taken with the Solar and Heliospheric Observatory's Solar Ultraviolet Measurements of Emitted Radiation (SOHO/SUMER) in lines formed at temperatures from 80,000 to 1.6 MK. The instrument was pointed to a single location and took a series of 90 s exposures. Two-dimensional context was provided by the Transition Region and Coronal Explorer (TRACE) in the UV and EUV and the Kanzelhohe Solar Observatory in H-alpha. Two dynamic features were studied in depth: an activated prominence and repeated motions in a loop near the prominence. We calculated three-dimensional geometries and trajectories, differential emission measure, and limits on the mass, pressure, average density, and kinetic and thermal energies. These observations provide important tests for models of dynamics in prominences and cool (approx. 10(exp 5) K)loops, which will ultimately lead to a better understanding the mechanism(s) leading to energy and mass flow in these solar features.

  12. Experimental and numerical study of open-air active cooling

    NASA Astrophysics Data System (ADS)

    Al-Fifi, Salman Amsari

    The topic of my thesis is Experimental and Numerical Study of Open Air Active Cooling. The present research is intended to investigate experimentally and Numerically the effectiveness of cooling large open areas like stadiums, shopping malls, national gardens, amusement parks, zoos, transportation facilities and government facilities or even in buildings outdoor gardens and patios. Our cooling systems are simple cooling fans with different diameters and a mist system. This type of cooling systems has been chosen among the others to guarantee less energy consumption, which will make it the most favorable and applicable for cooling such places mentioned above. In the experiments, the main focus is to study the temperature domain as a function of different fan diameters aerodynamically similar in different heights till we come up with an empirical relationship that can determine the temperature domain for different fan diameters and for different heights of these fans. The experimental part has two stages. The first stage is devoted to investigate the maximum range of airspeed and profile for three different fan diameters and for different heights without mist, while the second stage is devoted to investigate the maximum range of temperature and profile for the three different diameter fans and for different heights with mist. The computational study is devoted to built an experimentally verified mathematical model to be used in the design and optimization of water mist cooling systems, and to compare the mathematical results to the experimental results and to get an insight of how to apply such evaporative mist cooling for different places for different conditions. In this study, numerical solution is presented based on experimental conditions, such dry bulb temperature, wet bulb temperature, relative humidity, operating pressure and fan airspeed. In the computational study, all experimental conditions are kept the same for the three fans except the fan airspeed

  13. Structural cooling fluid tube for supporting a turbine component and supplying cooling fluid to transition section

    DOEpatents

    Charron, Richard; Pierce, Daniel

    2015-08-11

    A shaft cover support for a gas turbine engine is disclosed. The shaft cover support not only provides enhanced support to a shaft cover of the gas turbine engine, but also includes a cooling fluid chamber for passing fluids from a rotor air cooling supply conduit to an inner ring cooling manifold. Furthermore, the shaft cover support may include a cooling shield supply extending from the cooling fluid chamber between the radially outward inlet and the radially inward outlet on the radially extending region and in fluid communication with the cooling fluid chamber for providing cooling fluids to a transition section. The shaft cover support may also provide additional stiffness and reduce interference of the flow from the compressor. In addition, the shaft cover support accommodates a transition section extending between compressor and turbine sections of the gas turbine engine.

  14. High quality actively cooled plasma facing components for fusion

    SciTech Connect

    Nygren, R.

    1993-12-31

    This paper interweaves some suggestions for developing actively-cooled PFCs (plasma facing components) for future fusion devices with supporting examples taken from the design, fabrication and operation of Tore Supra`s Phase III Outboard Pump Limiter (OPL). This actively-cooled midplane limiter, designed for heat and particle removal during long pulse operation, has been operated in essentially thermally steady state conditions. From experience with testing to identify braze flaws in the OPL, recommendations are made to analyze the impact of joining flaws on thermal-hydraulic performance of PFCs and to validate a method of inspection for such flaws early in the design development. Capability for extensive in-service monitoring of future PFCs is also recommended and the extensive calorimetry and IR thermography used to confirm and update safe operating limits for power handling of the OPL are reviewed.

  15. Thermal/structural analysis of a transpiration cooled nozzle

    NASA Technical Reports Server (NTRS)

    Gregory, Peyton B.; Thompson, Jon E.; Babcock, Dale A.; Gray, Carl E., Jr.; Mouring, Chris A.

    1992-01-01

    The 8-foot High Temperature Tunnel (HTT) at LaRC is a combustion driven, high enthalpy blow down wind tunnel. In Mar. 1991, during check out of the transpiration cooled nozzle, pieces of platelets were found in the tunnel test section. It was determined that incorrect tolerancing between the platelets and the housing was the primary cause of the platelet failure. An analysis was performed to determine the tolerance layout between the platelets and the housing to meet the structural and performance criteria under a range of thermal, pressure, and bolt preload conditions. Three recommendations resulted as a product of this analysis.

  16. Modelization of the thermal coupling between the ITER TF coil conductor and the structure cooling circuit

    NASA Astrophysics Data System (ADS)

    Gauthier, F.; Bessette, D.; Hoa, C.; Rousset, B.; Lacroix, B.

    2016-12-01

    The ITER Toroidal Field (TF) coils are required not to quench during the most demanding event: a plasma disruption followed by a fast discharge of the Central Solenoid (CS), the Poloidal Field (PF) coils and the Correction Coils (CC). This event creates large heat deposition in the ITER magnet stainless steel structures in addition to the conductor AC losses. In order to prevent quench occurring in the TF conductor, cooling channels, implemented in the TF coil structure (TFCS), have to remove a large fraction of the heat deposited. The first integrated TF and structure mock-up has been manufactured and then tested in the HELIOS cryogenic test facility (CEA Grenoble) to determine the thermal coupling between the TFCS and the TF conductor, both actively cooled by supercritical helium at 4.4 K and 5 bar. It consists in a stainless steel casing, a cooling pipe glued with resin in the casing groove, winding pack (WP) ground insulation, a radial plate and a copper dummy cable-in-conduit-conductor (CICC). Steady state as well as transient thermal characterizations have been completed in May 2015. Simulation results by thermal hydraulic codes (VENECIA/SuperMagnet) and some of the experimental data are presented and discussed. The thermal coupling between the helium in the cooling tube and the TF coil structure is then modelled as an equivalent heat transfer coefficient in order to simplify the thermal hydraulic (TH) models. Comparison between simplified coupling and detailed coupling is presented.

  17. Activity and Kinematics of Cool and Ultracool Dwarfs

    NASA Astrophysics Data System (ADS)

    Schmidt, Sarah Jane

    The ages of cool and ultracool dwarfs are particularly important. For cool M dwarfs, accurate ages combined with their ubiquity in the stellar disk could lead to a new level of precision in age dating the Galaxy. A better understanding of the chromospheres of M dwarfs could provide important clues about the relationship between activity and age in these low mass stars. Ultracool (late-M and L) dwarfs have the distinction of including both warm, young brown dwarfs and stars with mean ages more representative of the stellar disk. Kinematics are a source of mean ages and could provide or confirm discriminating features between stars and brown dwarfs. This thesis is composed of several different projects, each investigating the activity or kinematics of cool or ultracool dwarfs. First, a sample of nearly 500 L dwarfs selected from SDSS DR7 photometry and spectroscopy is examined; we discovered 200 new L dwarfs and found evidence of a bias towards red J - KS colors in the entire population of previously known L dwarfs. Using the three-dimensional kinematics of 300 SDSS DR7 L dwarfs, we find that their kinematics are consistent with those of the stellar disk and include a previously undetected thick disk component. We also confirmed a relationship between age and J - KS color (due to our large sample of UVW motions and unbiased J - KS colors), with blue L dwarfs having hotter kinematics (consistent with older ages) and redder L dwarfs having colder, younger kinematics. The DR7 L dwarf sample showed no distinct kinematic difference between young brown dwarfs and disk-age stars, perhaps due to a bias towards early spectral types. In order to probe the kinematic distribution of L dwarfs in a volume-limited sample, we began a survey of radial velocities of nearby (d<20pc) L dwarfs using the TripleSpec instrument on the ARC 3.5-m telescope at APO. While several reduction packages were tested on the TripleSpec data, none were found to provide reductions of sufficient quality

  18. Characterization of AN Actively Cooled Metal Foil Thermal Radiation Shield

    NASA Astrophysics Data System (ADS)

    Feller, J. R.; Kashani, A.; Helvensteijn, B. P. M.; Salerno, L. J.

    2010-04-01

    Zero boil-off (ZBO) or reduced boil-off (RBO) systems that involve active cooling of large cryogenic propellant tanks will most likely be required for future space exploration missions. For liquid oxygen or methane, such systems could be implemented using existing high technology readiness level (TRL) cryocoolers. However, for liquid hydrogen temperatures (˜20 K) no such coolers exist. In order to partially circumvent this technology gap, the concept of broad area cooling (BAC) has been developed, whereby a low mass thermal radiation shield could be maintained at temperatures around 100 K by steady circulation of cold pressurized gas through a network of narrow tubes. By this method it is possible to dramatically reduce the radiative heat leak to the 20 K tank. A series of experiments, designed to investigate the heat transfer capabilities of BAC systems, have been conducted at NASA Ames Research Center (ARC). Results of the final experiment in this series, investigating heat transfer from a metal foil film to a distributed cooling line, are presented here.

  19. CHARACTERIZATION OF AN ACTIVELY COOLED METAL FOIL THERMAL RADIATION SHIELD

    SciTech Connect

    Feller, J. R.; Salerno, L. J.; Kashani, A.; Helvensteijn, B. P. M.

    2010-04-09

    Zero boil-off (ZBO) or reduced boil-off (RBO) systems that involve active cooling of large cryogenic propellant tanks will most likely be required for future space exploration missions. For liquid oxygen or methane, such systems could be implemented using existing high technology readiness level (TRL) cryocoolers. However, for liquid hydrogen temperatures (approx20 K) no such coolers exist. In order to partially circumvent this technology gap, the concept of broad area cooling (BAC) has been developed, whereby a low mass thermal radiation shield could be maintained at temperatures around 100 K by steady circulation of cold pressurized gas through a network of narrow tubes. By this method it is possible to dramatically reduce the radiative heat leak to the 20 K tank. A series of experiments, designed to investigate the heat transfer capabilities of BAC systems, have been conducted at NASA Ames Research Center (ARC). Results of the final experiment in this series, investigating heat transfer from a metal foil film to a distributed cooling line, are presented here.

  20. The structure and energy balance of cool star atmospheres

    NASA Technical Reports Server (NTRS)

    Linsky, J. L.

    1982-01-01

    The atmospheric structure and energy balance phenomena associated with magnetic fields in the Sun are reviewed and it is shown that similar phenomena occur in cool stars. The evidence for the weakening or disappearance of transition regions and coronae is discussed together with the appearance of extended cool chromospheres with large mass loss, near V-R = 0.80 in the H-R diagram. Like the solar atmosphere, these atmospheres are not homogeneous and there is considerable evidence for plage regions with bright TR emission lines that overlie dark (presumably magnetic) star spots. The IUE observations are providing important information on the energy balance in these atmospheres that should guide theoretical calculations of the nonradiative heating rate. Recent high dispersion spectra are providing unique information concerning which components of close binary systems are the dominant contributors to the observed emission. A recent unanticipated discovery is that the transition lines are redshifted (an antiwind) in DRa (G2 Ib) and perhaps other stars. Finally, the G and K giants and supergiants are classified into three groups depending on whether their atmospheres are dominated by closed magnetic flux tubes, open field geometries, or a predominately open geometry with a few closed flux tubes embedded.

  1. Small Spacecraft Active Thermal Control: Micro-Vascular Composites Enable Small Satellite Cooling

    NASA Technical Reports Server (NTRS)

    Ghosh, Alexander

    2016-01-01

    The Small Spacecraft Integrated Power System with Active Thermal Control project endeavors to achieve active thermal control for small spacecraft in a practical and lightweight structure by circulating a coolant through embedded micro-vascular channels in deployable composite panels. Typically, small spacecraft rely on small body mounted passive radiators to discard heat. This limits cooling capacity and leads to the necessity to design for limited mission operations. These restrictions severely limit the ability of the system to dissipate large amounts of heat from radios, propulsion systems, etc. An actively pumped cooling system combined with a large deployable radiator brings two key advantages over the state of the art for small spacecraft: capacity and flexibility. The use of a large deployable radiator increases the surface area of the spacecraft and allows the radiation surface to be pointed in a direction allowing the most cooling, drastically increasing cooling capacity. With active coolant circulation, throttling of the coolant flow can enable high heat transfer rates during periods of increased heat load, or isolate the radiator during periods of low heat dissipation.

  2. RF ACCELERATING STRUCTURE FOR THE MUON COOLING EXPERIMENT.

    SciTech Connect

    CORLETT,J.; GREEN,M.; LI,D.; HOLTKAMP,N.; MORETTI,A.; KIRK,H.G.; PALMER,R.B.; ZHAO,Y.; SUMMERS,D.

    1999-03-29

    The ionization cooling of muons requires longitudinal acceleration of the muons after scattering in a hydrogen target. In order to maximize the accelerating voltage, we propose using linear accelerating structures with cells bounded by thin beryllium metal foils. This produces an on-axis field equivalent to the maximum surface field, whereas with beam-pipes the accelerating field is approximately half that of the peak surface field in the cavity. The muons interact only weakly with the thin foils. A {pi}/2 interleaved cavity structure has been chosen, with alternate cells coupled together externally, and the two groups of cells fed in quadrature. At present they are considering an operating temperature of 77K to gain a factor of at least two in Q-value over room temperature. The authors describe the design of the {pi}/2 interleaved cavity structure, design of an alternative {pi}-mode open structure, preliminary experimental results from a low-power test cavity, and plans for high-power testing.

  3. Feasibility of Actively Cooled Silicon Nitride Airfoil for Turbine Applications Demonstrated

    NASA Technical Reports Server (NTRS)

    Bhatt, Ramakrishna T.

    2001-01-01

    Nickel-base superalloys currently limit gas turbine engine performance. Active cooling has extended the temperature range of service of nickel-base superalloys in current gas turbine engines, but the margin for further improvement appears modest. Therefore, significant advancements in materials technology are needed to raise turbine inlet temperatures above 2400 F to increase engine specific thrust and operating efficiency. Because of their low density and high-temperature strength and thermal conductivity, in situ toughened silicon nitride ceramics have received a great deal of attention for cooled structures. However, the high processing costs and low impact resistance of silicon nitride ceramics have proven to be major obstacles for widespread applications. Advanced rapid prototyping technology in combination with conventional gel casting and sintering can reduce high processing costs and may offer an affordable manufacturing approach. Researchers at the NASA Glenn Research Center, in cooperation with a local university and an aerospace company, are developing actively cooled and functionally graded ceramic structures. The objective of this program is to develop cost-effective manufacturing technology and experimental and analytical capabilities for environmentally stable, aerodynamically efficient, foreign-object-damage-resistant, in situ toughened silicon nitride turbine nozzle vanes, and to test these vanes under simulated engine conditions. Starting with computer aided design (CAD) files of an airfoil and a flat plate with internal cooling passages, the permanent and removable mold components for gel casting ceramic slips were made by stereolithography and Sanders machines, respectively. The gel-cast part was dried and sintered to final shape. Several in situ toughened silicon nitride generic airfoils with internal cooling passages have been fabricated. The uncoated and thermal barrier coated airfoils and flat plates were burner rig tested for 30 min without

  4. Human paranasal sinuses and selective brain cooling: a ventilation system activated by yawning?

    PubMed

    Gallup, Andrew C; Hack, Gary D

    2011-12-01

    The function of the paranasal sinuses has been a controversial subject since the time of Galen, with many different theories advanced about their biological significance. For one, the paranasal sinuses have been regarded as warmers of respiratory air, when in actuality these structures appear to function in cooling the blood. In fact, human paranasal sinuses have been shown to have higher volumes in individuals living in warmer climates, and thus may be considered radiators of the brain. The literature suggests that the transfer of cool venous blood from the paranasal sinuses to the dura mater may provide a mechanism for the convection process of cooling produced by the evaporation of mucus within human sinuses. In turn, the dura mater may transmit these temperature changes, initiated by the cool venous blood from the heat-dissipating surfaces of the sinuses, to the cerebrospinal fluid compartments. Furthermore, it has recently been demonstrated in cadaveric dissections that the thin bony posterior wall of the maxillary sinus serves as an origin for both medial and lateral pterygoid muscle segments, an anatomic finding that had been previously underappreciated in the literature. The present authors hypothesize that the thin posterior wall of the maxillary sinus may flex during yawning, operating like a bellows pump, actively ventilating the sinus system, and thus facilitating brain cooling. Such a powered ventilation system has not previously been described in humans, although an analogous system has been reported in birds.

  5. The structure, energy balance, and winds of cool stars

    NASA Technical Reports Server (NTRS)

    Linsky, J. L.

    1982-01-01

    The phenomena associated with magnetic fields in the Sun are summarized and it is shown that similar phenomena occur in cool stars. High dispersion spectra are providing unique information concerning densities, atmospheric extension, and emission line widths. A recent unanticipated discovery is that the transition lines are redshifted (an antiwind) in beta Dra (G2 Ib) and perhaps other stars. This is interpreted as indicating downflows in closed magnetic flux tubes as are seen in the solar flux tubes above sunspots. The G and K giants and supergiants are classified as active stars, quiet stars, or hybrid stars depending on whether their atmospheres are dominated by closed magnetic flux tubes, open field geometries, or a predominately open geometry with a few closed flux tubes embedded.

  6. Structural evolution in the crystallization of rapid cooling silver melt

    SciTech Connect

    Tian, Z.A.; Dong, K.J.; Yu, A.B.

    2015-03-15

    The structural evolution in a rapid cooling process of silver melt has been investigated at different scales by adopting several analysis methods. The results testify Ostwald’s rule of stages and Frank conjecture upon icosahedron with many specific details. In particular, the cluster-scale analysis by a recent developed method called LSCA (the Largest Standard Cluster Analysis) clarified the complex structural evolution occurred in crystallization: different kinds of local clusters (such as ico-like (ico is the abbreviation of icosahedron), ico-bcc like (bcc, body-centred cubic), bcc, bcc-like structures) in turn have their maximal numbers as temperature decreases. And in a rather wide temperature range the icosahedral short-range order (ISRO) demonstrates a saturated stage (where the amount of ico-like structures keeps stable) that breeds metastable bcc clusters. As the precursor of crystallization, after reaching the maximal number bcc clusters finally decrease, resulting in the final solid being a mixture mainly composed of fcc/hcp (face-centred cubic and hexagonal-closed packed) clusters and to a less degree, bcc clusters. This detailed geometric picture for crystallization of liquid metal is believed to be useful to improve the fundamental understanding of liquid–solid phase transition. - Highlights: • A comprehensive structural analysis is conducted focusing on crystallization. • The involved atoms in our analysis are more than 90% for all samples concerned. • A series of distinct intermediate states are found in crystallization of silver melt. • A novelty icosahedron-saturated state breeds the metastable bcc state.

  7. Structural cooling fluid tube for supporting a turbine component and supplying cooling fluid

    SciTech Connect

    Charron, Richard; Pierce, Daniel

    2015-02-24

    A shaft cover support for a gas turbine engine is disclosed. The shaft cover support not only provides enhanced support to a shaft cover of the gas turbine engine, but also includes a cooling fluid chamber for passing fluids from a rotor air cooling supply conduit to an inner ring cooling manifold. As such, the shaft cover support accomplishes in a single component what was only partially accomplished in two components in conventional configurations. The shaft cover support may also provide additional stiffness and reduce interference of the flow from the compressor. In addition, the shaft cover support accommodates a transition section extending between compressor and turbine sections of the engine. The shaft cover support has a radially extending region that is offset from the inlet and outlet that enables the shaft cover support to surround the transition, thereby reducing the overall length of this section of the engine.

  8. Fluid flow and heat convection studies for actively cooled airframes

    NASA Astrophysics Data System (ADS)

    Mills, A. F.

    This report details progress made on the jet impingement - liquid crystal - digital imaging experiment. With the design phase complete, the experiment is currently in the construction phase. In order to reach this phase two design related issues were resolved. The first issue was to determine NASP leading edge active cooling design parameters. Meetings were arranged with personnel at SAIC International, Torrance, CA in order to obtain recent publications that characterized expected leading edge heat fluxes as well as other details of NASP operating conditions. The information in these publications was used to estimate minimum and maximum jet Reynolds numbers needed to accomplish the required leading edge cooling, and to determine the parameters of the experiment. The details of this analysis are shown in Appendix A. One of the concerns for the NASP design is that of thermal stress due to large surface temperature gradients. Using a series of circular jets to cool the leading edge will cause a non-uniform temperature distribution and potentially large thermal stresses. Therefore it was decided to explore the feasibility of using a slot jet to cool the leading edge. The literature contains many investigations into circular jet heat transfer but few investigations of slot jet heat transfer. The first experiments will be done on circular jets impinging on a fiat plate and results compared to previously published data to establish the accuracy of the method. Subsequent experiments will be slot jets impinging on full scale models of the NASP leading edge. Table 1 shows the range of parameters to be explored. Next a preliminary design of the experiment was done. Previous papers which used a similar experimental technique were studied and elements of those experiments adapted to the jet impingement study. Trade-off studies were conducted to determine which design was the least expensive, easy to construct, and easy to use. Once the final design was settled, vendors were

  9. Fluid flow and heat convection studies for actively cooled airframes

    NASA Technical Reports Server (NTRS)

    Mills, A. F.

    1993-01-01

    This report details progress made on the jet impingement - liquid crystal - digital imaging experiment. With the design phase complete, the experiment is currently in the construction phase. In order to reach this phase two design related issues were resolved. The first issue was to determine NASP leading edge active cooling design parameters. Meetings were arranged with personnel at SAIC International, Torrance, CA in order to obtain recent publications that characterized expected leading edge heat fluxes as well as other details of NASP operating conditions. The information in these publications was used to estimate minimum and maximum jet Reynolds numbers needed to accomplish the required leading edge cooling, and to determine the parameters of the experiment. The details of this analysis are shown in Appendix A. One of the concerns for the NASP design is that of thermal stress due to large surface temperature gradients. Using a series of circular jets to cool the leading edge will cause a non-uniform temperature distribution and potentially large thermal stresses. Therefore it was decided to explore the feasibility of using a slot jet to cool the leading edge. The literature contains many investigations into circular jet heat transfer but few investigations of slot jet heat transfer. The first experiments will be done on circular jets impinging on a fiat plate and results compared to previously published data to establish the accuracy of the method. Subsequent experiments will be slot jets impinging on full scale models of the NASP leading edge. Table 1 shows the range of parameters to be explored. Next a preliminary design of the experiment was done. Previous papers which used a similar experimental technique were studied and elements of those experiments adapted to the jet impingement study. Trade-off studies were conducted to determine which design was the least expensive, easy to construct, and easy to use. Once the final design was settled, vendors were

  10. Actively cooled plasma electrode for long pulse operations in a cesium-seeded negative ion source

    NASA Astrophysics Data System (ADS)

    Fujiwara, Yukio; Watanabe, Kazuhiro; Okumura, Yoshikazu; Trainham, Rusty; Jacquot, Claude

    2005-01-01

    An actively cooled plasma electrode has been developed for long pulse operation in a cesium-seeded negative ion source. To keep the electrode temperature at about 300°C, which is the optimum range of temperature to enhance cesium effects, the electrode cooling structure has been designed using three-dimensional numerical simulation assuming that the heat flux from the source plasma was 15W/cm2. Water cooling tubes were brazed to the plasma electrode substrate with spacers made of stainless steel, which acts as a thermal resistance. The fabricated plasma electrode has been tested in a cesium-seeded volume negative ion source called Kamaboko source. The temperature of the electrode reached 280°C for the arc power of 41kW, which is the operating condition required for producing D- beams with current densities exceeding 20mA/cm2. It was demonstrated that the actively cooled plasma electrode is applicable to long pulse operations, meeting the temperature requirement for optimizing the surface-production process of negative ions in the cesium-seeded ion source.

  11. Heat pipe and surface mass transfer cooling of hypersonic vehicle structures

    NASA Technical Reports Server (NTRS)

    Colwell, Gene T.; Modlin, James M.

    1992-01-01

    The problem of determining the feasibility of cooling hypersonic vehicle leading-edge structures exposed to severe aerodynamic surface heating using heat pipe and mass transfer cooling techniques is addressed. A description is presented of a numerical finite-difference-based hypersonic leading-edge cooling model incorporating poststartup liquid metal heat pipe cooling with surface transpiration and film cooling to predict the transient structural temperature distributions and maximum surface temperatures of hypersonic vehicle leading edge. An application of this model to the transient cooling of a typical aerospace plane wing leading-edge section. The results of this application indicated that liquid metal heat pipe cooling alone is insufficient to maintain surface temperatures below an assumed maximum level of 1800 K for about one-third of a typical aerospace plane ascent trajectory through the earth's atmosphere.

  12. Active cooling for downhole instrumentation: Preliminary analysis and system selection

    SciTech Connect

    Bennett, G.A.

    1988-03-01

    A feasibility study and a series of preliminary designs and analyses were done to identify candidate processes or cycles for use in active cooling systems for downhole electronic instruments. A matrix of energy types and their possible combinations was developed and the energy conversion process for each pari was identified. The feasibility study revealed conventional as well as unconventional processes and possible refrigerants and identified parameters needing further clarifications. A conceptual design or series od oesigns for each system was formulated and a preliminary analysis of each design was completed. The resulting coefficient of performance for each system was compared with the Carnot COP and all systems were ranked by decreasing COP. The system showing the best combination of COP, exchangeability to other operating conditions, failure mode, and system serviceability is chosen for use as a downhole refrigerator. 85 refs., 48 figs., 33 tabs.

  13. Active solar heating and cooling information user study

    SciTech Connect

    Belew, W.W.; Wood, B.L.; Marle, T.L.; Reinhardt, C.L.

    1981-01-01

    The results of a series of telephone interviews with groups of users of information on active solar heating and cooling (SHAC). An earlier study identified the information user groups in the solar community and the priority (to accelerate solar energy commercialization) of getting information to each group. In the current study only high-priority groups were examined. Results from 19 SHAC groups respondents are analyzed in this report: DOE-Funded Researchers, Non-DOE-Funded Researchers, Representatives of Manufacturers (4 groups), Distributors, Installers, Architects, Builders, Planners, Engineers (2 groups), Representatives of Utilities, Educators, Cooperative Extension Service County Agents, Building Owners/Managers, and Homeowners (2 groups). The data will be used as input to the determination of information products and services the Solar Energy Research Institute, the Solar Energy Information Data Bank Network, and the entire information outreach community should be preparing and disseminating.

  14. Annual DOE active solar heating and cooling contractors' review meeting. Premeeting proceedings and project summaries

    SciTech Connect

    None,

    1981-09-01

    Ninety-three project summaries are presented which discuss the following aspects of active solar heating and cooling: Rankine solar cooling systems; absorption solar cooling systems; desiccant solar cooling systems; solar heat pump systems; solar hot water systems; special projects (such as the National Solar Data Network, hybrid solar thermal/photovoltaic applications, and heat transfer and water migration in soils); administrative/management support; and solar collector, storage, controls, analysis, and materials technology. (LEW)

  15. Thermal analysis and cooling structure design of the primary collimator in CSNS/RCS

    NASA Astrophysics Data System (ADS)

    Zou, Yi-Qing; Wang, Na; Kang, Ling; Qu, Hua-Min; He, Zhe-Xi; Yu, Jie-Bing

    2013-05-01

    The rapid cycling synchrotron (RCS) of the China Spallation Neutron Source (CSNS) is a high intensity proton ring with beam power of 100 kW. In order to control the residual activation to meet the requirements of hands-on maintenance, a two-stage collimation system has been designed for the RCS. The collimation system consists of one primary collimator made of thin metal to scatter the beam and four secondary collimators as absorbers. Thermal analysis is an important aspect in evaluating the reliability of the collimation system. The calculation of the temperature distribution and thermal stress of the primary collimator with different materials is carried out by using ANSYS code. In order to control the temperature rise and thermal stress of the primary collimator to a reasonable level, an air cooling structure is intended to be used. The mechanical design of the cooling structure is presented, and the cooling efficiency with different chin numbers and wind velocity is also analyzed. Finally, the fatigue lifetime of the collimator under thermal shocks is estimated.

  16. Micro-Stirling Active Cooling Module (MS/ACM) for DoD Electronics Systems

    DTIC Science & Technology

    2012-03-01

    Micro- Stirling Active Cooling Module (MS/ACM) for DoD Electronics Systems Douglas S. Beck Beck Engineering , Inc. 1490 Lumsden Road, Port Orchard...refrigerator. We are developing for DARPA a cm-scale Micro- Stirling Active Cooling Module (MS/ACM) micro- refrigerator to benefit the DoD systems. Under...a DARPA contract, we are designing, building, and demonstrating a breadboard MS/ACM. Keywords: Stirling ; cooler; active cooling module; micro

  17. Ducting arrangement for cooling a gas turbine structure

    SciTech Connect

    Lee, Ching-Pang; Morrison, Jay A.

    2015-07-21

    A ducting arrangement (10) for a can annular gas turbine engine, including: a duct (12, 14) disposed between a combustor (16) and a first row of turbine blades and defining a hot gas path (30) therein, the duct (12, 14) having raised geometric features (54) incorporated into an outer surface (80); and a flow sleeve (72) defining a cooling flow path (84) between an inner surface (78) of the flow sleeve (72) and the duct outer surface (80). After a cooling fluid (86) traverses a relatively upstream raised geometric feature (90), the inner surface (78) of the flow sleeve (72) is effective to direct the cooling fluid (86) toward a landing (94) separating the relatively upstream raised geometric feature (90) from a relatively downstream raised geometric feature (94).

  18. Wissler Simulations of a Liquid Cooled and Ventilation Garment (LCVG) for Extravehicular Activity (EVA)

    NASA Technical Reports Server (NTRS)

    Kesterson, Matthew; Bue, Grant; Trevino, Luis

    2006-01-01

    In order to provide effective cooling for astronauts during extravehicular activities (EVAs), a liquid cooling and ventilation garment (LCVG) is used to remove heat by a series off tubes through which cooling water is circulated. To better predict the effectiveness of the LCG and determine possible modifications to improve performance, computer simulations dealing with the interaction of the cooling garment with the human body have been run using the Wissler Human Model. Simulations have been conducted to predict the heat removal rate for various liquid cooled garment configurations. The current LCVG uses 48 cooling tubes woven into a fabric with cooling water flowing through the tubes. The purpose of the current project is to decrease the overall weight of the LCVG system. In order to achieve this weight reduction, advances in the garment heat removal rates need to be obtained. Currently, increasing the fabric s thermal conductivity along with also examining an increase in the cooling tube conductivity to more efficiently remove the excess heat generated during EVA is being simulated. Initial trials varied cooling water temperature, water flow rate, garment conductivity, tube conductivity, and total number of cooling tubes in the LCVG. Results indicate that the total number of cooling tubes could be reduced to 22 and still achieve the desired heat removal rate of 361 W. Further improvements are being made to the garment network used in the model to account for temperature gradients associated with the spacing of the cooling tubes over the surface of the garment

  19. Simulation of an active cooling system for photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Abdelhakim, Lotfi

    2016-06-01

    Photovoltaic cells are devices that convert solar radiation directly into electricity. However, solar radiation increases the photovoltaic cells temperature [1] [2]. The temperature has an influence on the degradation of the cell efficiency and the lifetime of a PV cell. This work reports on a water cooling technique for photovoltaic panel, whereby the cooling system was placed at the front surface of the cells to dissipate excess heat away and to block unwanted radiation. By using water as a cooling medium for the photovoltaic solar cells, the overheating of closed panel is greatly reduced without prejudicing luminosity. The water also acts as a filter to remove a portion of solar spectrum in the infrared band but allows transmission of the visible spectrum most useful for the PV operation. To improve the cooling system efficiency and electrical efficiency, uniform flow rate among the cooling system is required to ensure uniform distribution of the operating temperature of the PV cells. The aims of this study are to develop a 3D thermal model to simulate the cooling and heat transfer in Photovoltaic panel and to recommend a cooling technique for the PV panel. The velocity, pressure and temperature distribution of the three-dimensional flow across the cooling block were determined using the commercial package, Fluent. The second objective of this work is to study the influence of the geometrical dimensions of the panel, water mass flow rate and water inlet temperature on the flow distribution and the solar panel temperature. The results obtained by the model are compared with experimental results from testing the prototype of the cooling device.

  20. Termination of epileptiform activity by cooling in rat hippocampal slice epilepsy models.

    PubMed

    Motamedi, Gholam K; Salazar, Patricia; Smith, Eric L; Lesser, Ronald P; Webber, William R S; Ortinski, Pavel I; Vicini, Stefano; Rogawski, Michael A

    2006-08-01

    Cooling has been shown to terminate experimentally induced epileptiform activity in models of epilepsy without causing injury to the cooled brain, suggesting that cooling could represent an approach to seizure control in intractable focal epilepsies. Here we sought to determine the most effective way to apply cooling to abort spontaneous epileptiform discharges in in vitro brain slice models. We induced spontaneous epileptiform activity in rat brain slices by exposure to 4-aminopyridine (4-AP), 4-AP plus bicuculline, and Mg(2+)-free artificial CSF (aCSF) at 28-34 degrees C. Extracellular field recordings were made at hippocampal or neocortical sites. Slice temperature was reduced by perfusion with cold aCSF. Rapid cooling at rates of 2-5 degrees C/s was compared to cooling at slower rates of 0.1-1 degrees C/s. Cooling at both rates reversibly aborted epileptiform discharges in all three models and at all recording sites. With rapid cooling, small temperature drops were highly effective in terminating discharges, an effect that was sustained for as long as the reduced temperature level was maintained. In contrast, slow cooling required much larger temperature drops to inhibit discharges. With slow cooling, absolute temperature drops to 21-22 degrees C caused a 90% reduction in event frequency, but cooling to 14-15 degrees C was required to terminate discharges. We conclude that rapid cooling as effectively aborts discharges in in vitro epilepsy models as does slow cooling, but the magnitude of the temperature change required is less. Practical devices to inhibit seizure activity may only need to induce small temperature drops, if the cooling can be applied sufficiently rapidly.

  1. MEMS Device Being Developed for Active Cooling and Temperature Control

    NASA Technical Reports Server (NTRS)

    Moran, Matthew E.

    2001-01-01

    High-capacity cooling options remain limited for many small-scale applications such as microelectronic components, miniature sensors, and microsystems. A microelectromechanical system (MEMS) is currently under development at the NASA Glenn Research Center to meet this need. It uses a thermodynamic cycle to provide cooling or heating directly to a thermally loaded surface. The device can be used strictly in the cooling mode, or it can be switched between cooling and heating modes in milliseconds for precise temperature control. Fabrication and assembly are accomplished by wet etching and wafer bonding techniques routinely used in the semiconductor processing industry. Benefits of the MEMS cooler include scalability to fractions of a millimeter, modularity for increased capacity and staging to low temperatures, simple interfaces and limited failure modes, and minimal induced vibration.

  2. Study of a fail-safe abort system for an actively cooled hypersonic aircraft. Volume 1: Technical summary

    NASA Technical Reports Server (NTRS)

    Pirello, C. J.; Herring, R. L.

    1976-01-01

    Conceptual designs of a fail-safe abort system for hydrogen fueled actively cooled high speed aircraft are examined. The fail-safe concept depends on basically three factors: (1) a reliable method of detecting a failure or malfunction in the active cooling system, (2) the optimization of abort trajectories which minimize the descent heat load to the aircraft, and (3) fail-safe thermostructural concepts to minimize both the weight and the maximum temperature the structure will reach during descent. These factors are examined and promising approaches are evaluated based on weight, reliability, ease of manufacture and cost.

  3. Active cooling design for scramjet engines using optimization methods

    NASA Technical Reports Server (NTRS)

    Scotti, Stephen J.; Martin, Carl J.; Lucas, Stephen H.

    1988-01-01

    A methodology for using optimization in designing metallic cooling jackets for scramjet engines is presented. The optimal design minimizes the required coolant flow rate subject to temperature, mechanical-stress, and thermal-fatigue-life constraints on the cooling-jacket panels, and Mach-number and pressure contraints on the coolant exiting the panel. The analytical basis for the methodology is presented, and results for the optimal design of panels are shown to demonstrate its utility.

  4. Active cooling design for scramjet engines using optimization methods

    NASA Technical Reports Server (NTRS)

    Scotti, Stephen J.; Martin, Carl J.; Lucas, Stephen H.

    1988-01-01

    A methodology for using optimization in designing metallic cooling jackets for scramjet engines is presented. The optimal design minimizes the required coolant flow rate subject to temperature, mechanical-stress, and thermal-fatigue-life constraints on the cooling-jacket panels, and Mach-number and pressure constraints on the coolant exiting the panel. The analytical basis for the methodology is presented, and results for the optimal design of panels are shown to demonstrate its utility.

  5. UV Chromospheric Activity in Cool, Short-Period Contact Binaries

    NASA Technical Reports Server (NTRS)

    Hrivnak, Bruce J.

    2000-01-01

    We have completed our analysis of the IUE spectra of the short-period contact binary OO Aql. OO Aql is a rare W UMa-type eclipsing binary in which the two solar-type stars may have only recently evolved into contact. The binary has an unusually high mass ratio (0.84), and a relatively long orbital period (0.506 d) for its spectral type (mid-G). Twelve ultraviolet spectra of OO Aql were obtained in 1988 with the IUE satellite, including a series of consecutive observations that cover nearly a complete orbital cycle. Chromospheric activity is studied by means of the Mg II h+k emission at 2800 A. The Mg II emission is found to vary, even when the emission is normalized to the adjacent continuum flux. This variation may be correlated with orbital phase in the 1988 observations. It also appears that the normalized Mg H emission varies with time, as seen in spectra obtained at two different epochs in 1988 and when compared with two spectra obtained several years earlier. The level of chromospheric activity in OO Aql is less than that of other W UMa-type binaries of similar colors, but this is attributed to its early stage of contact binary evolution. Ultraviolet light curves were composed from measurements of the ultraviolet continuum in the spectra. These were analyzed along with visible light curves of OO Aql to determine the system parameters. The large wavelength range in the light curves enabled a well-constrained fit to a cool spot in the system. A paper on these results is scheduled for publication in the February 2001 issue of the Astronomical Journal.

  6. Directly connected heat exchanger tube section and coolant-cooled structure

    DOEpatents

    Chainer, Timothy J.; Coico, Patrick A.; Graybill, David P.; Iyengar, Madhusudan K.; Kamath, Vinod; Kochuparambil, Bejoy J.; Schmidt, Roger R.; Steinke, Mark E.

    2015-09-15

    A method is provided for fabricating a cooling apparatus for cooling an electronics rack, which includes an air-to-liquid heat exchanger, one or more coolant-cooled structures, and a tube. The heat exchanger is associated with the electronics rack and disposed to cool air passing through the rack, includes a plurality of coolant-carrying tube sections, each tube section having a coolant inlet and outlet, one of which is coupled in fluid communication with a coolant loop to facilitate flow of coolant through the tube section. The coolant-cooled structure(s) is in thermal contact with an electronic component(s) of the rack, and facilitates transfer of heat from the component(s) to the coolant. The tube connects in fluid communication one coolant-cooled structure and the other of the coolant inlet or outlet of the one tube section, and facilitates flow of coolant directly between that coolant-carrying tube section of the heat exchanger and the coolant-cooled structure.

  7. Measurements in large pool fires with an actively cooled calorimeter

    SciTech Connect

    Koski, J.A.; Wix, S.D.

    1995-12-31

    The pool fire thermal test described in Safety Series 6 published by the International Atomic Energy Agency (IAEA) or Title 10, Code of Federal Regulations, Part 71 (10CFR71) in the United States is one of the most difficult tests that a container for larger ``Type B`` quantities of nuclear materials must pass. If retests of a container are required, costly redesign and project delays can result. Accurate measurements and modeling of the pool fire environment will ultimately lower container costs by assuring that containers past the pool fire test on the first attempt. Experiments indicate that the object size or surface temperature of the container can play a role in determining local heat fluxes that are beyond the effects predicted from the simple radiative heat transfer laws. An analytical model described by Nicolette and Larson 1990 can be used to understand many of these effects. In this model a gray gas represents soot particles present in the flame structure. Close to the container surface, these soot particles are convectively and radiatively cooled and interact with incident energy from the surrounding fire. This cooler soot cloud effectively prevents some thermal radiation from reaching the container surface, reducing the surface heat flux below the value predicted by a transparent medium model. With some empirical constants, the model suggested by Nicolette and Larson can be used to more accurately simulate the pool fire environment. Properly formulated, the gray gas approaches also fast enough to be used with standard commercial computer codes to analyze shipping containers. To calibrate this type of model, accurate experimental measurements of radiative absorption coefficients, flame temperatures, and other parameters are necessary. A goal of the calorimeter measurements described here is to obtain such parameters so that a fast, useful design tool for large pool fires can be constructed.

  8. Active Control of Jets in Cross-Flow for Film Cooling Applications

    NASA Technical Reports Server (NTRS)

    Nikitopoulos, Dimitris E.

    2003-01-01

    Jets in cross-flow have applications in film cooling of gas turbine vanes, blades and combustor liners. Their cooling effectiveness depends on the extent to which the cool jet-fluid adheres to the cooled component surface. Lift-off of the cooling jet flow or other mechanisms promoting mixing, cause loss of cooling effectiveness as they allow the hot "free-stream" fluid to come in contact with the component surface. The premise of this project is that cooling effectiveness can be improved by actively controlling (e.9. forcing, pulsing) the jet flow. Active control can be applied to prevent/delay lift-off and suppress mixing. Furthermore, an actively controlled film-cooling system coupled with appropriate sensory input (e.g. temperature or heat flux) can adapt to spatial and temporal variations of the hot-gas path. Thus, it is conceivable that the efficiency of film-cooling systems can be improved, resulting in coolant fluid economy. It is envisioned that Micro Electro-Mechanical Systems (MEMS) will play a role in the realization of such systems. As a first step, a feasibility study will be conducted to evaluate the concept, identify actuation and sensory elements and develop a control strategy. Part of this study will be the design of a proof-of-concept experiment and collection of necessary data.

  9. Receptor guanylyl cyclase-G is a novel thermosensory protein activated by cool temperatures.

    PubMed

    Chao, Ying-Chi; Chen, Chih-Cheng; Lin, Yuh-Charn; Breer, Heinz; Fleischer, Joerg; Yang, Ruey-Bing

    2015-02-03

    Transmembrane guanylyl cyclases (GCs), with activity regulated by peptide ligands and/or calcium-binding proteins, are essential for various physiological and sensory processes. The mode of activation of the GC subtype GC-G, which is expressed in neurons of the Grueneberg ganglion that respond to cool temperatures, has been elusive. In searching for appropriate stimuli to activate GC-G, we found that its enzymatic activity is directly stimulated by cool temperatures. In this context, it was observed that dimerization/oligomerization of GC-G, a process generally considered as critical for enzymatic activity of GCs, is strongly enhanced by coolness. Moreover, heterologous expression of GC-G in cultured cells rendered these cells responsive to coolness; thus, the protein might be a sensor for cool temperatures. This concept is supported by the observation of substantially reduced coolness-induced response of Grueneberg ganglion neurons and coolness-evoked ultrasonic vocalization in GC-G-deficient mouse pups. GC-G may be a novel thermosensory protein with functional implications for the Grueneberg ganglion, a sensory organ responding to cool temperatures.

  10. Subcontracted activities related to TES for building heating and cooling

    NASA Technical Reports Server (NTRS)

    Martin, J.

    1980-01-01

    The subcontract program elements related to thermal energy storage for building heating and cooling systems are outlined. The following factors are included: subcontracts in the utility load management application area; life and stability testing of packaged low cost energy storage materials; and development of thermal energy storage systems for residential space cooling. Resistance storage heater component development, demonstration of storage heater systems for residential applications, and simulation and evaluation of latent heat thermal energy storage (heat pump systems) are also discussed. Application of thermal energy storage for solar application and twin cities district heating are covered including an application analysis and technology assessment of thermal energy storage.

  11. Subcontracted activities related to TES for building heating and cooling

    NASA Astrophysics Data System (ADS)

    Martin, J.

    1980-03-01

    The subcontract program elements related to thermal energy storage for building heating and cooling systems are outlined. The following factors are included: subcontracts in the utility load management application area; life and stability testing of packaged low cost energy storage materials; and development of thermal energy storage systems for residential space cooling. Resistance storage heater component development, demonstration of storage heater systems for residential applications, and simulation and evaluation of latent heat thermal energy storage (heat pump systems) are also discussed. Application of thermal energy storage for solar application and twin cities district heating are covered including an application analysis and technology assessment of thermal energy storage.

  12. Thermal Design of Vapor Cooling of Flight Vehicle Structures Using LH2 Boil-Off

    NASA Technical Reports Server (NTRS)

    Wang, Xiao-Yen; Zoeckler, Joseph

    2015-01-01

    Using hydrogen boil-off vapor to cool the structure of a flight vehicle cryogenic upper stage can reduce heat loads to the stage and increase the usable propellant in the stage or extend the life of the stage. The hydrogen vapor can be used to absorb incoming heat as it increases in temperature before being vented overboard. In theory, the amount of heat leaking into the hydrogen tank from the structure will be reduced if the structure is cooled using the propellant boil-off vapor. However, the amount of boil-off vapor available to be used for cooling and the reduction in heat leak to the propellant tank are dependent to each other. The amount of heat leak reduction to the LH2 tank also depends on the total heat load on the stage and the vapor cooling configurations.

  13. Active noise canceling system for mechanically cooled germanium radiation detectors

    SciTech Connect

    Nelson, Karl Einar; Burks, Morgan T

    2014-04-22

    A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

  14. Directly connected heat exchanger tube section and coolant-cooled structure

    DOEpatents

    Chainer, Timothy J; Coico, Patrick A; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Steinke, Mark E

    2014-04-01

    A cooling apparatus for an electronics rack is provided which includes an air-to-liquid heat exchanger, one or more coolant-cooled structures and a tube. The heat exchanger, which is associated with the electronics rack and disposed to cool air passing through the rack, includes a plurality of distinct, coolant-carrying tube sections, each tube section having a coolant inlet and a coolant outlet, one of which is coupled in fluid communication with a coolant loop to facilitate flow of coolant through the tube section. The coolant-cooled structure(s) is in thermal contact with an electronic component(s) of the rack, and facilitates transfer of heat from the component(s) to the coolant. The tube connects in fluid communication one coolant-cooled structure and the other of the coolant inlet or outlet of the one tube section, and facilitates flow of coolant directly between that coolant-carrying tube section of the heat exchanger and the coolant-cooled structure.

  15. Structural Oil Pan With Integrated Oil Filtration And Cooling System

    DOEpatents

    Freese, V, Charles Edwin

    2000-05-09

    An oil pan for an internal combustion engine includes a body defining a reservoir for collecting engine coolant. The reservoir has a bottom and side walls extending upwardly from the bottom to present a flanged lip through which the oil pan may be mounted to the engine. An oil cooler assembly is housed within the body of the oil pan for cooling lubricant received from the engine. The body includes an oil inlet passage formed integrally therewith for receiving lubricant from the engine and delivering lubricant to the oil cooler. In addition, the body also includes an oil pick up passage formed integrally therewith for providing fluid communication between the reservoir and the engine through the flanged lip.

  16. Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

    NASA Astrophysics Data System (ADS)

    Lobato, I.; Rojas, J.; Landauro, C. V.; Torres, J.

    2009-02-01

    The structural evolution and dynamics of silver nanodrops Ag2869 (4.4 nm in diameter) under rapid cooling conditions have been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modelled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique are used to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of 1.5625 × 1013 K s-1 the nanoparticles preserve an amorphous-like structure containing a large amount of 1551 and 1541 pairs which correspond to icosahedral symmetry. For a lower cooling rate (1.5625 × 1012 K s-1), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the face centred cubic and hexagonal close packed structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small, but in correspondence with the structural changes.

  17. Development and testing of heat transport fluids for use in active solar heating and cooling systems

    NASA Technical Reports Server (NTRS)

    Parker, J. C.

    1981-01-01

    Work on heat transport fluids for use with active solar heating and cooling systems is described. Program objectives and how they were accomplished including problems encountered during testing are discussed.

  18. Design and fabrication of a stringer stiffened discrete-tube actively cooled panel for a hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Anthony, F. M.; Halenbrook, R. G.

    1981-01-01

    A 0.61 x 1.22 m (2 x 4 ft) test panel was fabricated and delivered to the Langley Research Center for assessment of the thermal and structural features of the optimized panel design. The panel concept incorporated an aluminum alloy surface panel actively cooled by a network of discrete, parallel, redundant, counterflow passage interconnected with appropriate manifolding, and assembled by adhesive bonding. The cooled skin was stiffened with a mechanically fastened conventional substructure of stringers and frames. A 40 water/60 glycol solution was the coolant. Low pressure leak testing, radiography, holography and infrared scanning were applied at various stages of fabrication to assess integrity and uniformity. By nondestructively inspecting selected specimens which were subsequently tested to destruction, it was possible to refine inspection standards as applied to this cooled panel design.

  19. Three Dimensional Structures in the Atmospheres of Cool Stars

    NASA Technical Reports Server (NTRS)

    Walter, Frederick M.

    1997-01-01

    This grant has supported my GHRS-related activities since 1990. This included both instrumental calibration activities and independent scientific research using the Goddard High Resolution Spectrograph on the Hubble Space Telescope. The activities under this grant are essentially complete. Publications to date which have resulted in whole or in part from this grant are included.

  20. Cool-season grass sward structure influences intake of grazing cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cool-season grasses differ in sward structure, such as canopy height and the distribution of leaves and stems throughout the canopy, that may influence intake by grazing livestock. We determined the relationship between the sward structure of four grasses (meadow fescue, orchardgrass, quackgrass, an...

  1. Active cooling solutions for high power laser diodes stacks

    NASA Astrophysics Data System (ADS)

    Karni, Yoram; Klumel, Genady; Levy, Moshe; Berk, Yuri; Openhaim, Yaki; Gridish, Yaakov; Elgali, Asher; Avisar, Meir; Blonder, Moshe; Sagy, Hila; Gertsenshtein, Alex

    2008-02-01

    High power water cooled diode lasers find increasing demand in biomedical, cosmetic and industrial applications, where very high brightness and power are required. The high brightness is achieved either by increasing the power of each bar or by reducing the emitting area of the stacks. Two new products will be presented: Horizontal CW stacks with output power as high as 1kW using 80 W bars with emitting area width as low as 50 μm Vertical QCW stacks with output power as high as 1.2kW using 120 W bars. Heat removal from high power laser stacks often requires microchannel coolers operated with finely filtered deionized (DI) water. However, for certain industrial applications the reliability of this cooling method is widely considered insufficient due to leakage failures caused the highly corrosive DI water. Two solutions to the above problem will be discussed. A microchannel cooler-based package, which vastly reduces the corrosion problem, and a novel high-power laser diode stack that completely eliminates it. The latter solution is especially effective for pulsed applications in high duty cycle range.

  2. Investigation of structure of superconducting power transmission cables with LN2 counter-flow cooling

    NASA Astrophysics Data System (ADS)

    Furuse, Mitsuho; Fuchino, Shuichiro; Higuchi, Noboru

    2003-04-01

    Establishment of long-distance cooling techniques and design of a compact cross section are required for development of HTC superconducting underground power cables. To save space of return coolant, a counter-flow cooling system appears promising. However, it is difficult to cool down long cables because of heat exchange between counter-flows due to high thermal conductivity of dielectric materials which separate both flows in range of liquid nitrogen temperature. We estimated temperature distributions analytically along model HTS power cables with counter-flow. Results of calculation showed that when liquid-nitrogen-impregnated polypropylene laminated paper was chosen for a dielectric material, great thickness was required to reduce heat exchange between counter-flows. We investigated various cable structures to optimize the counter-flow cooling system and cable size.

  3. Thermo-Elastic Analysis of Internally Cooled Structures Using a Higher Order Theory

    NASA Technical Reports Server (NTRS)

    Arnold, Steven M.; Bednarcyk, Brett A.; Aboudi, Jacob

    2001-01-01

    This paper presents the results of a study on the thermomechanical behavior of internally cooled silicon nitride structures. Silicon nitride is under consideration for elevated temperature aerospace engine applications. and techniques for lowering the operating temperature of structures composed of this material are under development. Lowering the operating temperature provides a large payoff in terms of fatigue life and may be accomplished through the use of thermal barrier coatings (TBC's) and the novel concept of included cooling channels. Herein, an in-depth study is performed on the behavior of a flame-impinged silicon nitride plate with a TBC and internal channels cooled by forced air. The analysis is performed using the higher order theory for functionally graded materials (HOTFGM), which has been developed through NASA Glenn Research Center funding over the past several years. HOTFGM was chosen over the traditional finite element approach as a prelude to an examination of functionally graded silicon nitride structures for which HOTFGM is ideally suited. To accommodate the analysis requirement% of the internally cooled plate problem, two crucial enhancements were made to the two-dimensional Cartesian-based version of HOTFGM. namely, incorporation of internal boundary capabilities and incorporation of convective boundary conditions. Results indicate the viability and large benefits of cooling the plate via forced air through cooling channels. Furthermore, cooling can positively impact the stress and displacement fields present in the plate, yielding an additional payoff in terms of fatigue life. Finally, a spin-off capability resulted from inclusion of internal boundaries within HOTFGM; the ability to simulate the thermo-elastic response of structures with curved surfaces. This new capability is demonstrated, and through comparison with an analytical solution, shown to be viable and accurate.

  4. Application of formal optimization techniques in thermal/structural design of a heat-pipe-cooled panel for a hypersonic vehicle

    NASA Technical Reports Server (NTRS)

    Camarda, Charles J.; Riley, Michael F.

    1987-01-01

    Nonlinear mathematical programming methods are used to design a radiantly cooled and heat-pipe-cooled panel for a Mach 6.7 transport. The cooled portion of the panel is a hybrid heat-pipe/actively cooled design which uses heat pipes to transport the absorbed heat to the ends of the panel where it is removed by active cooling. The panels are optimized for minimum mass and to satisfy a set of heat-pipe, structural, geometric, and minimum-gage constraints. Two panel concepts are investigated: cylindrical heat pipes embedded in a honeycomb core and an integrated design which uses a web-core heat-pipe sandwich concept. The latter was lighter and resulted in a design which was less than 10 percent heavier than an all actively cooled concept. The heat-pipe concept, however, is redundant and can sustain a single-point failure, whereas the actively cooled concept cannot. An additional study was performed to determine the optimum number of coolant manifolds per panel for a minimum-mass design.

  5. Brazing of the Tore Supra actively cooled Phase III Limiter

    SciTech Connect

    Nygren, R.E.; Walker, C.A.; Lutz, T.J.; Hosking, F.M.; McGrath, R.T.

    1993-12-31

    The head of the water-cooled Tore Supra Phase 3 Limiter is a bank of 14 round OFHC copper tubes, curved to fit the plasma radius, onto which several hundred pyrolytic graphite (PG) tiles and a lesser number of carbon fiber composite tiles are brazed. The small allowable tolerances for fitting the tiles to the tubes and mating of compound curvatures made the brazing and fabrication extremely challenging. The paper describes the fabrication process with emphasis on the procedure for brazing. In the fixturing for vacuum furnace brazing, the tiles were each independently clamped to the tube with an elaborate set of window frame clamps. Braze quality was evaluated with transient heating tests. Some rebrazing was necessary.

  6. Cooling rate dependence of simulated Cu64.5Zr35.5 metallic glass structure

    NASA Astrophysics Data System (ADS)

    Ryltsev, R. E.; Klumov, B. A.; Chtchelkatchev, N. M.; Shunyaev, K. Yu.

    2016-07-01

    Using molecular dynamics simulations with embedded atom model potential, we study structural evolution of Cu64.5Zr35.5 alloy during the cooling in a wide range of cooling rates γ ∈ (1.5 ṡ 109, 1013) K/s. Investigating short- and medium-range orders, we show that the structure of Cu64.5Zr35.5 metallic glass essentially depends on cooling rate. In particular, a decrease of the cooling rate leads to an increase of abundances of both the icosahedral-like clusters and Frank-Kasper Z16 polyhedra. The amounts of these clusters in the glassy state drastically increase at the γmin = 1.5 ṡ 109 K/s. Analysing the structure of the glass at γmin, we observe the formation of nano-sized crystalline grain of Cu2Zr intermetallic compound with the structure of Cu2Mg Laves phase. The structure of this compound is isomorphous with that for Cu5Zr intermetallic compound. Both crystal lattices consist of two types of clusters: Cu-centered 13-atom icosahedral-like cluster and Zr-centered 17-atom Frank-Kasper polyhedron Z16. That suggests the same structural motifs for the metallic glass and intermetallic compounds of Cu-Zr system and explains the drastic increase of the abundances of these clusters observed at γmin.

  7. Structural and Microhardness Changes After Turning of the AISI 1045 Steel for Minimum Quantity Cooling Lubrication

    NASA Astrophysics Data System (ADS)

    Maruda, Radoslaw W.; Krolczyk, Grzegorz M.; Michalski, Mariusz; Nieslony, Piotr; Wojciechowski, Szymon

    2016-11-01

    This work presents the cooling effect under minimum quantity cooling lubrication and dry cutting on structural changes and microhardness of the ferritic-pearlitic AISI 1045 steel after turning. Due to the fact that the AISI 1045 steel has a two-phase structure, microhardness tests using the Vickers method were conducted with a load of 0.05 HV separately for ferrite and pearlite grains. The tests showed that cooling of the cutting zone under minimum quantity cooling lubrication (MQCL) condition decreased the depth of the hardened layer compared to dry cutting by approximately 40% for both pearlite and ferrite. Scanning electron microscopy analysis revealed that applying MQCL limits the formation of plastic deformations, among others, by reducing the surface crumple zone by approximately 50% compared to dry cutting. As a result of cooling being applied to the cutting zone using the MQCL method, the average diameter of ferrite grains has been decreased in the entire surface area compared to dry cutting. When using dry cutting, clear structural changes of the surface layer were also observed. This may be the result of sulfide inclusions which have formed, causing microcracks on the edge of the hardened layer and surface deformation visible as notches.

  8. Structural and Microhardness Changes After Turning of the AISI 1045 Steel for Minimum Quantity Cooling Lubrication

    NASA Astrophysics Data System (ADS)

    Maruda, Radoslaw W.; Krolczyk, Grzegorz M.; Michalski, Mariusz; Nieslony, Piotr; Wojciechowski, Szymon

    2017-01-01

    This work presents the cooling effect under minimum quantity cooling lubrication and dry cutting on structural changes and microhardness of the ferritic-pearlitic AISI 1045 steel after turning. Due to the fact that the AISI 1045 steel has a two-phase structure, microhardness tests using the Vickers method were conducted with a load of 0.05 HV separately for ferrite and pearlite grains. The tests showed that cooling of the cutting zone under minimum quantity cooling lubrication (MQCL) condition decreased the depth of the hardened layer compared to dry cutting by approximately 40% for both pearlite and ferrite. Scanning electron microscopy analysis revealed that applying MQCL limits the formation of plastic deformations, among others, by reducing the surface crumple zone by approximately 50% compared to dry cutting. As a result of cooling being applied to the cutting zone using the MQCL method, the average diameter of ferrite grains has been decreased in the entire surface area compared to dry cutting. When using dry cutting, clear structural changes of the surface layer were also observed. This may be the result of sulfide inclusions which have formed, causing microcracks on the edge of the hardened layer and surface deformation visible as notches.

  9. Structural and thermal modeling of a cooled CCD camera

    NASA Astrophysics Data System (ADS)

    Ahmad, Anees; Arndt, Thomas D.; Gross, Robert; Hahn, Mark; Panasiti, Mark

    2001-11-01

    This paper presents structural and thermal modeling of a high-performance CCD camera designed to operate under severe environments. Minimizing the dark current noise required the CCD to be maintained at low temperature while the camera operated in a 70 degrees C environment. A thermoelectric cooler (TEC) was selected due to its simplicity, and relatively low cost. Minimizing the thermal parasitic loads due to conduction and convection, and maximizing the heat sink performance was critical in this design. The critical structural features of this camera are the CCD leads and the bond joint that holds the CCD in alignment relative to the lens. The CCD leads are susceptible to fatigue failure when subjected to random vibrations for an extended period of time. This paper outlines the methods used to model and analyze the CCD leads for fatigue, the supportive vibration testing performed and the steps taken to correct for structural inadequacies found in the original design. The key results of all this thermal and structural modeling and testing are presented.

  10. Influence of cooling rate on activity of ionotropic glutamate receptors in brain slices at hypothermia.

    PubMed

    Mokrushin, Anatoly A; Pavlinova, Larisa I; Borovikov, Sergey E

    2014-08-01

    Hypothermia is a known approach in the treatment of neurological pathologies. Mild hypothermia enhances the therapeutic window for application of medicines, while deep hypothermia is often accompanied by complications, including problems in the recovery of brain functions. The purpose of present study was to investigate the functioning of glutamate ionotropic receptors in brain slices cooled with different rates during mild, moderate and deep hypothermia. Using a system of gradual cooling combined with electrophysiological recordings in slices, we have shown that synaptic activity mediated by the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and N-methyl-D-aspartate receptors in rat olfactory cortex was strongly dependent on the rate of lowering the temperature. High cooling rate caused a progressive decrease in glutamate receptor activity in brain slices during gradual cooling from mild to deep hypothermia. On the contrary, low cooling rate slightly changed the synaptic responses in deep hypothermia. The short-term potentiation may be induced in slices by electric tetanization at 16 °C in this case. Hence, low cooling rate promoted preservation of neuronal activity and plasticity in the brain tissue.

  11. System and method of active vibration control for an electro-mechanically cooled device

    DOEpatents

    Lavietes, Anthony D.; Mauger, Joseph; Anderson, Eric H.

    2000-01-01

    A system and method of active vibration control of an electro-mechanically cooled device is disclosed. A cryogenic cooling system is located within an environment. The cooling system is characterized by a vibration transfer function, which requires vibration transfer function coefficients. A vibration controller generates the vibration transfer function coefficients in response to various triggering events. The environments may differ by mounting apparatus, by proximity to vibration generating devices, or by temperature. The triggering event may be powering on the cooling system, reaching an operating temperature, or a reset action. A counterbalance responds to a drive signal generated by the vibration controller, based on the vibration signal and the vibration transfer function, which adjusts vibrations. The method first places a cryogenic cooling system within a first environment and then generates a first set of vibration transfer function coefficients, for a vibration transfer function of the cooling system. Next, the cryogenic cooling system is placed within a second environment and a second set of vibration transfer function coefficients are generated. Then, a counterbalance is driven, based on the vibration transfer function, to reduce vibrations received by a vibration sensitive element.

  12. Analyzing the structure of the optical path difference of the supersonic film cooling

    NASA Astrophysics Data System (ADS)

    Ding, Haolin; Yi, Shihe; Fu, Jia; He, Lin

    2016-10-01

    While high-speed aircraft are flying in the atmosphere, its optical-hood is subjected to severe aerodynamic heating. Supersonic film cooling method can effectively isolate external heating, but the flow structures formed by the supersonic film cooling can cause the beam degradation and affect the imaging quality. To research the aero-optics of supersonic film cooling, an experimental model was adopted in this paper, its mainstream Mach number 3.4, designed jet Mach number 2.5, measured jet Mach number 2.45. High-resolution images of flow were acquired by the nano-based planar laser scattering (NPLS) technique, by reconstructing the density field of supersonic film cooling, and then, the optical path difference (OPD) were acquired by the ray-tracing method. Depending on the comparison between K-H vortex and OPD distribution, the valleys of OPD correspond to the vortex `rollers' and the peaks to the `braids'. However, the corresponding relationship becomes quite irregular for the flow field with developed vortices, and cannot be summarized in this manner. And then, the OPD were analyzed by correlation function and structure function, show that, there is a relationship between the shape of OPD correlation function and the vortex structure, the correlation function type changed with the development of the vortex. The correctness that the mixing layer makes a main contribution to the aero-optics of supersonic film cooling was verified, and the structure function of aero-optical distortion has a power relationship that is similar to that of atmospheric optics. At last, the power spectrum corresponding to the typical region of supersonic film cooling were acquired by improved periodgram.

  13. Experimental study on active cooling systems used for thermal management of high-power multichip light-emitting diodes.

    PubMed

    Kaya, Mehmet

    2014-01-01

    The objective of this study was to develop suitable cooling systems for high-power multichip LEDs. To this end, three different active cooling systems were investigated to control the heat generated by the powering of high-power multichip LEDs in two different configurations (30 and 2 × 15 W). The following cooling systems were used in the study: an integrated multi-fin heat sink design with a fan, a cooling system with a thermoelectric cooler (TEC), and a heat pipe cooling device. According to the results, all three systems were observed to be sufficient for cooling high-power LEDs. Furthermore, it was observed that the integrated multifin heat sink design with a fan was the most efficient cooling system for a 30 W high-power multichip LED. The cooling system with a TEC and 46 W input power was the most efficient cooling system for 2 × 15 W high-power multichip LEDs.

  14. Process analyses of ITER Toroidal Field Structure cooling scheme

    NASA Astrophysics Data System (ADS)

    Maekawa, R.; Takami, S.; Iwamoto, A.; Chang, H. S.; Forgeas, A.; Chalifour, M.; Serio, L.

    2014-09-01

    Process studies for Toroidal Field Structure (TF ST) system with a dedicated Auxiliary Cold Box (ACB-ST) have been conducted under 15 MA baseline, including plasma disruptions. ACB-ST consists of two heat exchangers immersed in the Liquid Helium (LHe) subcooler, which are placed at the inlet/outlet of a Supercritical Helium (SHe) cold circulator (centrifugal pump). Robustness of ACB-ST is a key to achieve the stability of TF coil operation since it provides the thermal barrier at the interface of the TF Winding Pack (WP) with ST. The paper discusses the control logic for the nominal plasma operating scenario and for Mitigation to regulate the dynamic heat loads on ST. In addition, the operation field of a cold circulator is described in the case of plasma disruptions. The required performance of heat exchangers in the ACB-ST is assessed based on the expected operating conditions.

  15. COOLING TOWER PUMP HOUSE, TRA606. ELEVATIONS, STRUCTURAL AND ROOF PLAN, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    COOLING TOWER PUMP HOUSE, TRA-606. ELEVATIONS, STRUCTURAL AND ROOF PLAN, DETAILS. BLAW-KNOX 3150-807-1, 2/1950. INL INDEX NO. 531-0607-00-098-100670. REV. 3. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  16. CALL-FOR-ABSTRACTS: SYMPOSIUM ON TECHNOLOGIES FOR PROTECTING AQUATIC ORGANISMS FROM COOLING WATER INTAKE STRUCTURES

    EPA Science Inventory

    Section 316(b) of the Clean Water Act requires EPA to ensure that the location, design, construction, and capacity of cooling water intake structures reflect the best technology available for minimizing adverse environmental impacts. In February 2002, the EPA approved a proposed ...

  17. RBM3 mediates structural plasticity and protective effects of cooling in neurodegeneration

    PubMed Central

    Peretti, Diego; Bastide, Amandine; Radford, Helois; Verity, Nicholas; Molloy, Colin; Martin, Maria Guerra; Moreno, Julie A.; Steinert, Joern R; Smith, Tim; Dinsdale, David; Willis, Anne E.; Mallucci, Giovanna R.

    2014-01-01

    In the healthy adult brain synapses are continuously remodelled through a process of elimination and formation known as structural plasticity1. Reduction in synapse number is a consistent early feature of neurodegenerative diseases2, 3, suggesting deficient compensatory mechanisms. While much is known about toxic processes leading to synaptic dysfunction and loss in these disorders2,3, how synaptic regeneration is affected is unknown. In hibernating mammals, cooling induces loss of synaptic contacts, which are reformed on rewarming, a form of structural plasticity4, 5. We have found that similar changes occur in artificially cooled laboratory rodents. Cooling and hibernation also induce a number cold-shock proteins in the brain, including the RNA binding protein, RBM36. The relationship of such proteins to structural plasticity is unknown. Here we show that synapse regeneration is impaired in mouse models of neurodegenerative disease, in association with the failure to induce RBM3. In both prion-infected and 5×FAD (Alzheimer-type) mice7, the capacity to regenerate synapses after cooling declined in parallel with the loss of induction of RBM3. Enhanced expression of RBM3 in the hippocampus prevented this deficit and restored the capacity for synapse reassembly after cooling. Further, RBM3 over-expression, achieved either by boosting endogenous levels through hypothermia prior to the loss of the RBM3 response, or by lentiviral delivery, resulted in sustained synaptic protection in 5×FAD mice and throughout the course of prion disease, preventing behavioural deficits and neuronal loss and significantly prolonging survival. In contrast, knockdown of RBM3 exacerbated synapse loss in both models and accelerated disease and prevented the neuroprotective effects of cooling. Thus, deficient synapse regeneration, mediated at least in part by failure of the RBM3 stress response, contributes to synapse loss throughout the course of neurodegenerative disease. The data support

  18. Formation of the structures from dusty clusters in neon dc discharge under cooling

    NASA Astrophysics Data System (ADS)

    Polyakov, D. N.; Shumova, V. V.; Vasilyak, L. M.

    2016-11-01

    The formation of structures consisted of dusty clusters in plasma at the discharge tube cooling to a temperature of liquid nitrogen was discovered. The dependence of the reduced electric field in the positive column of a discharge on gas temperature was experimentally measured. Depending on the pressure of neon were observed the different structural transitions in the regions of growing current-voltage characteristics at low discharge currents ≤ 1 mA. It was found that the regions of existence of structured clusters and the regions of structural transitions were characterized by the higher values of the reduced electric field than the regions of destruction of ordered structures.

  19. Physical and Structural Studies on the Cryo-cooling of Insulin Crystals

    NASA Technical Reports Server (NTRS)

    Lovelace, J.; Bellamy, H.; Snell, E. H.; Borgstahl, G.

    2003-01-01

    Reflection profiles were analyzed from microgravity-(mg) and earth-grown insulin crystals to measure mosaicity (h) and to reveal mosaic domain structure and composition. The effects of cryocooling on single and multi-domain crystals were compared. The effects of cryocooling on insulin structure were also re-examined. Microgravity crystals were larger, more homogeneous, and more perfect than earth crystals. Several mg crystals contained primarily a single mosaic domain with havg of 0.005deg. The earth crystals varied in quality and all contained multiple domains with havg of 0.031deg. Cryocooling caused a 43-fold increase in h for mg crystals (havg=0.217deg) and an %fold increase for earth crystals (havg=0.246deg). These results indicate that very well-ordered crystals are not completely protected from the stresses associated with cryocooling, especially when structural perturbations occur. However, there were differences in the reflection profiles. For multi-mosaic domain crystals, each domain individually broadened and separated from the other domains upon cryo-cooling. Cryo-cooling did not cause an increase in the number of domains. A crystal composed of a single domain retained this domain structure and the reflection profiles simply broadened. Therefore, an improved signal-to-noise ratio for each reflection was measured from cryo-cooled single domain crystals relative to cryo-cooled multi-domain crystals. This improved signal, along with the increase in crystal size, facilitated the measurement of the weaker high- resolution reflections. The observed broadening of reflection profiles indicates increased variation in unit cell dimensions which may be linked to cryo-cooling-associated structural changes and disorder.

  20. Titanium defect structure change after gas-phase hydrogenation at different temperatures and cooling rates

    NASA Astrophysics Data System (ADS)

    Mikhaylov, Andrey A.; Laptev, Roman S.; Kudiiarov, Viktor N.; Volokitina, Tatiana L.

    2016-11-01

    Influence of gas-phase hydrogenation temperature and cooling rate on defect structure of commercially pure titanium alloy was experimentally studied by means of positron annihilation spectroscopy. The change of temperature in the process of gas-phase hydrogenation was in the range of 500-700°C, while the change of cooling rate was in the range of 0.4-10.4°C/min. With increasing of gas-phase hydrogenation temperature, significant increase of hydrogen sorption rate was found. High temperature gas-phase hydrogenation of commercially pure titanium alloy lead to the formation of vacancy and hydrogen-vacancy complexes. For the same concentration of hydrogen, temperature variation or variation of cooling rate had no effect on the type of defect. However, this variation provides significant changes in defect concentration.

  1. Flow structure and heat exchange analysis in internal cooling channel of gas turbine blade

    NASA Astrophysics Data System (ADS)

    Szwaba, Ryszard; Kaczynski, Piotr; Doerffer, Piotr; Telega, Janusz

    2016-08-01

    This paper presents the study of the flow structure and heat transfer, and also their correlations on the four walls of a radial cooling passage model of a gas turbine blade. The investigations focus on heat transfer and aerodynamic measurements in the channel, which is an accurate representation of the configuration used in aeroengines. Correlations for the heat transfer coefficient and the pressure drop used in the design of radial cooling passages are often developed from simplified models. It is important to note that real engine passages do not have perfect rectangular cross sections, but include corner fillet, ribs with fillet radii and special orientation. Therefore, this work provides detailed fluid flow and heat transfer data for a model of radial cooling geometry which possesses very realistic features.

  2. Effect of cooling rate during solidification on the structure of high-speed steel powder particles

    SciTech Connect

    Ershova, L.S.; Smirnov, V.P.

    1985-08-01

    The structure and properties of a P/M high-speed steel form during solidification, hot plastic working, and subsequent heat treatment are the focus here. The character of steel structure variation under the action of high cooling rates during solidification has not yet been sufficiently investigated, therefore it is of interest to study the interrelationship between these factors. An R6M5F3 steel powder was produced by the atomization of molten metal in an apparatus constructed at the Ukranian Scientific-Research Institute of Special Steels, and divided into several fractions. A study was then made of the effect of cooling rate on the phase composition of the steel, degree of alloying of its solid solution and the microstructure and microhardness of the material. As a result of a higher rate of cooling, the amount of metastable M2C carbide inclusions in the structure of P/M R6M5F3 steel increases and the degree of bulk alloying of its grains grows. The increase in the microhardness of powder particles brought about by cooling at a higher rate is due to the formation of finer carbide inclusions during solidification, grain refinement, and an increased degree of alloying of the gamma and alpha solid solutions being formed.

  3. Thermal design for areas of interference heating on actively cooled hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Herring, R. L.; Stone, J. E.

    1978-01-01

    Numerous actively cooled panel design alternatives for application in regions on high speed aircraft that are subject to interference heating effects were studied. Candidate design concepts were evaluated using mass, producibility, reliability and inspectability/maintainability as figures of merit. Three design approaches were identified as superior within certain regimes of the matrix of design heating conditions considered. Only minor modifications to basic actively cooled panel design are required to withstand minor interference heating effects. Designs incorporating internally finned coolant tubes to augment heat transfer are recommended for moderate design heating conditions. At severe heating conditions, an insulated panel concept is required.

  4. Spectroscopic study of a dark lane and a cool loop in a solar limb active region by Hinode/EIS

    SciTech Connect

    Lee, Kyoung-Sun; Imada, S.; Moon, Y.-J.; Lee, Jin-Yi

    2014-01-10

    We investigated a cool loop and a dark lane over a limb active region on 2007 March 14 using the Hinode/EUV Imaging Spectrometer. The cool loop is clearly seen in the spectral lines formed at the transition region temperature. The dark lane is characterized by an elongated faint structure in the coronal spectral lines and is rooted on a bright point. We examined their electron densities, Doppler velocities, and nonthermal velocities as a function of distance from the limb. We derived electron densities using the density sensitive line pairs of Mg VII, Si X, Fe XII, Fe XIII, and Fe XIV spectra. We also compared the observed density scale heights with the calculated scale heights from each peak formation temperatures of the spectral lines under the hydrostatic equilibrium. We noted that the observed density scale heights of the cool loop are consistent with the calculated heights, with the exception of one observed cooler temperature; we also found that the observed scale heights of the dark lane are much lower than their calculated scale heights. The nonthermal velocity in the cool loop slightly decreases along the loop, while nonthermal velocity in the dark lane sharply falls off with height. Such a decrease in the nonthermal velocity may be explained by wave damping near the solar surface or by turbulence due to magnetic reconnection near the bright point.

  5. Thermal design and development of actively cooled brushes for compact homopolar generators

    NASA Astrophysics Data System (ADS)

    Makel, D. B.

    1986-11-01

    The thermal and hydraulic design of actively cooled current transfer brushes for compact homopolar generators (HPG) is described. The development of high-energy-density HPG's at the Center for Electromechanics at the University of Texas at Austin requires brushgear capable of handling high current densities and large thermal loads. Platelet technology has been applied in the design of actively cooled brushes with coolant injection directly from the brush contact face into the brush-rotor interface. Coolant channels a few thousandths of an inch in diameter have been designed in brushes constructed of photoetched platelets of copper (0.020 to 0.005 in. thick) and then bonded to form the cooled brush. Platelet construction of brushes also permits the incorporation of internal instrumentation for temperature measurement. The brushes have been designed to provide data on the effects of rotor speed, current level, coolant flow rate, and coolant injection pattern.

  6. Effect of cooling rate on structural and electromagnetic properties of high-carbon ferrochrome powders

    NASA Astrophysics Data System (ADS)

    Yang, Jian-ping; Chen, Jin; Hao, Jiu-jiu; Guo, Li-na; Liu, Jin-ying

    2016-03-01

    The structural and electromagnetic properties of high-carbon ferrochrome powders (HCFCP) obtained at different cooling rates were respectively investigated by means of optical microscope, X-ray diffractometer, electron probe as well as the vector network analyzer in the frequency range of 1-18 GHz. The results show that the cell structure of main phase, (Cr,Fe)7C3, transforms from hexagonal to orthogonal with the improvement of cooling rate. Meanwhile the mass ratio of Cr to Fe in (Cr,Fe)7C3 gradually declines, while that for CrFe goes up. Both the real part and the imaginary part of relative complex permittivity of HCFCP are in an increasing order with cooling rate rising in most frequencies. For comparison, the relative complex permeability presents an opposite changing tendency. The peaks of the imaginary part of relative complex permeability appearing in low and high frequencies are attributed to nature resonance. The reflection loss of HCFCP gradually decreases as cooling rate reduces and frequency enhances. At 2.45 GHz, the algebraic sum of dielectric loss factor and magnetic loss factor increases first and then decreases in the temperature extent from 298 K to 1273 K.

  7. Effects of Planetary Thermal Structure on the Ascent and Cooling of Magma on Venus

    NASA Technical Reports Server (NTRS)

    Sakimoto, Susan E. H.; Zuber, Maria T.

    1995-01-01

    Magellan radar images of the surface of Venus show a spatially broad distribution of volcanic features. Models of magmatic ascent processes to planetary surfaces indicate that the thermal structure of the interior significantly influences the rate of magmatic cooling and thus the amount of magma that can be transported to the surface before solidification. In order to understand which aspects of planetary thermal structure have the greatest influence on the cooling of buoyantly ascending magma, we have constructed magma cooling profiles for a plutonic ascent mechanism, and evaluated the profiles for variations in the surface and mantle temperature, surface temperature gradient, and thermal gradient curvature. Results show that, for a wide variety of thermal conditions, smaller and slower magma bodies are capable of reaching the surface on Venus compared to Earth, primarily due to the higher surface temperature of Venus. Little to no effect on the cooling and transport of magma are found to result from elevated mantle temperatures, elevation-dependent surface temperature variations, or details of the thermal gradient curvature. The enhanced tendency of magma to reach the surface on Venus may provide at least a partial explanation for the extensive spatial distribution of observed volcanism on the surface.

  8. Structure of steady state accretion shocks with several cooling functions: Closed integral-form solution

    NASA Technical Reports Server (NTRS)

    Wu, Kinwah; Chanmugam, G.; Shaviv, G.

    1994-01-01

    We present, for the first time, a closed integral-form solution to the accretion shock structures for the case where the cooling is due to optically thin bremsstrahlung emission and a series of power-law cooling functions of density and temperature. Our results can provide useful checks on numerical calculations and simple accurate estimates for valuable parameters such as the shock height. For the case where the cooling rate j = (2/3)Arho(exp 2)(P/rho)(exp 1/2)(1 + epsilon (sub s)(P/P(sub s)(exp alpha)(rho(sub s)/rho)(exp beta)), we find that a substantial amount of the accretion energy is released at the base of the accretion shock in the form of bremsstrahlung radiation. This implies that for a cyclotron-dominated shock (qualitatively given by alpha = 2.0, beta = 3.85, and epsilon(sub s) is much greater than 1), bremsstrahlung cooling still plays a crucial role in determining the shock structure. Our results are shown to be consistent with detailed numerical calculations.

  9. Microelectromechanical System (MEMS) Device Being Developed for Active Cooling and Temperature Control

    NASA Technical Reports Server (NTRS)

    Beach, Duane E.

    2003-01-01

    High-capacity cooling options remain limited for many small-scale applications such as microelectronic components, miniature sensors, and microsystems. A microelectromechanical system (MEMS) using a Stirling thermodynamic cycle to provide cooling or heating directly to a thermally loaded surface is being developed at the NASA Glenn Research Center to meet this need. The device can be used strictly in the cooling mode or can be switched between cooling and heating modes in milliseconds for precise temperature control. Fabrication and assembly employ techniques routinely used in the semiconductor processing industry. Benefits of the MEMS cooler include scalability to fractions of a millimeter, modularity for increased capacity and staging to low temperatures, simple interfaces, limited failure modes, and minimal induced vibration. The MEMS cooler has potential applications across a broad range of industries such as the biomedical, computer, automotive, and aerospace industries. The basic capabilities it provides can be categorized into four key areas: 1) Extended environmental temperature range in harsh environments; 2) Lower operating temperatures for electronics and other components; 3) Precision spatial and temporal thermal control for temperature-sensitive devices; and 4) The enabling of microsystem devices that require active cooling and/or temperature control. The rapidly expanding capabilities of semiconductor processing in general, and microsystems packaging in particular, present a new opportunity to extend Stirling-cycle cooling to the MEMS domain. The comparatively high capacity and efficiency possible with a MEMS Stirling cooler provides a level of active cooling that is impossible at the microscale with current state-of-the-art techniques. The MEMS cooler technology builds on decades of research at Glenn on Stirling-cycle machines, and capitalizes on Glenn s emerging microsystems capabilities.

  10. Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly

    NASA Technical Reports Server (NTRS)

    Viall, Nicholeen M.; Klimchuk, James A.

    2012-01-01

    A well known behavior of EUV light curves of discrete coronal loops is that the peak intensities of cooler channels or spectral lines are reached at progressively later times. This time lag is understood to be the result of hot coronal loop plasma cooling through these lower respective temperatures. However, loops typically comprise only a minority of the total emission in active regions. Is this cooling pattern a common property of active region coronal plasma, or does it only occur in unique circumstances, locations, and times? The new SDO/AIA data provide a wonderful opportunity to answer this question systematically for an entire active region. We measure the time lag between pairs of SDO/AIA EUV channels using 24 hours of images of AR 11082 observed on 19 June 2010. We find that there is a time-lag signal consistent with cooling plasma, just as is usually found for loops, throughout the active region including the diffuse emission between loops for the entire 24 hour duration. The pattern persists consistently for all channel pairs and choice of window length within the 24 hour time period, giving us confidence that the plasma is cooling from temperatures of greater than 3 MK, and sometimes exceeding 7 MK, down to temperatures lower than approx. 0.8 MK. This suggests that the bulk of the emitting coronal plasma in this active region is not steady; rather, it is dynamic and constantly evolving. These measurements provide crucial constraints on any model which seeks to describe coronal heating.

  11. Venus Mobile Explorer with RPS for Active Cooling: A Feasibility Study

    NASA Technical Reports Server (NTRS)

    Leifer, Stephanie D.; Green, Jacklyn R.; Balint, Tibor S.; Manvi, Ram

    2009-01-01

    We present our findings from a study to evaluate the feasibility of a radioisotope power system (RPS) combined with active cooling to enable a long-duration Venus surface mission. On-board power with active cooling technology featured prominently in both the National Research Council's Decadal Survey and in the 2006 NASA Solar System Exploration Roadmap as mission-enabling for the exploration of Venus. Power and cooling system options were reviewed and the most promising concepts modeled to develop an assessment tool for Venus mission planners considering a variety of future potential missions to Venus, including a Venus Mobile Explorer (either a balloon or rover concept), a long-lived Venus static lander, or a Venus Geophysical Network. The concepts modeled were based on the integration of General Purpose Heat Source (GPHS) modules with different types of Stirling cycle heat engines for power and cooling. Unlike prior investigations which reported on single point design concepts, this assessment tool allows the user to generate either a point design or parametric curves of approximate power and cooling system mass, power level, and number of GPHS modules needed for a "black box" payload housed in a spherical pressure vessel.

  12. Cooling rate effects on thermal, structural, and microstructural properties of bio-hydroxyapatite obtained from bovine bone.

    PubMed

    Ramirez-Gutierrez, Cristian F; Palechor-Ocampo, Anderzon F; Londoño-Restrepo, Sandra M; Millán-Malo, Beatriz M; Rodriguez-García, Mario E

    2016-02-01

    This article is focused on the study of cooling rate effects on the thermal, structural, and microstructural properties of hydroxyapatite (HAp) obtained from bovine bone. A three-step process was used to obtain BIO-HAp: hydrothermal, calcinations, and cooling. Calcined samples in a furnace and cooling in air (HAp-CAir), water (HAp-CW), and liquid nitrogen (HAp-CN2), as well as an air cooled sample inside the furnace (HAp-CFAir), were studied. According to this study, the low cooling rate that was achieved for air cooled samples inside the furnace produce single crystal BIO-HAp with better crystalline quality; other samples exhibited polycrystalline structures forming micron and submicron grains.

  13. Localized cooling of stems induces latewood formation and cambial dormancy during seasons of active cambium in conifers

    PubMed Central

    Begum, Shahanara; Kudo, Kayo; Matsuoka, Yugo; Nakaba, Satoshi; Yamagishi, Yusuke; Nabeshima, Eri; Rahman, Md Hasnat; Nugroho, Widyanto Dwi; Oribe, Yuichiro; Jin, Hyun-O; Funada, Ryo

    2016-01-01

    Background and Aims In temperate regions, trees undergo annual cycles of cambial growth, with periods of cambial activity and dormancy. Environmental factors might regulate the cambial growth, as well as the development of cambial derivatives. We investigated the effects of low temperature by localized cooling on cambial activity and latewood formation in two conifers, Chamaecyparis obtusa and Cryptomeria japonica. Methods A plastic rubber tube that contained cooled water was wrapped around a 30-cm-wide portion of the main stem of Chamaecyparis obtusa and Cryptomeria japonica trees during seasons of active cambium. Small blocks were collected from both cooled and non-cooled control portions of the stems for sequential observations of cambial activity and for anatomical measurements of cell morphology by light microscopy and image analysis. Key Results The effect of localized cooling was first observed on differentiating tracheids. Tracheids narrow in diameter and with significantly decreased cambial activity were evident 5 weeks after the start of cooling in these stems. Eight weeks after the start of cooling, tracheids with clearly diminished diameters and thickened cell walls were observed in these stems. Thus, localized low temperature induced narrow diameters and obvious thickening of secondary cell walls of tracheids, which were identified as latewood tracheids. Two months after the cessation of cooling, a false annual ring was observed and cambium became active again and produced new tracheids. In Cryptomeria japonica, cambial activity ceased earlier in locally cooled portions of stems than in non-cooled stems, indicating that the cambium had entered dormancy sooner in the cooled stems. Conclusions Artificial cooling of stems induced latewood formation and cessation of cambial activity, indicating that cambium and its derivatives can respond directly to changes in temperature. A decrease in the temperature of the stem is a critical factor in the control of

  14. Advanced fabrication techniques for hydrogen-cooled engine structures. Final report, October 1975-June 1982

    SciTech Connect

    Buchmann, O.A.; Arefian, V.V.; Warren, H.A.; Vuigner, A.A.; Pohlman, M.J.

    1985-11-01

    Described is a program for development of coolant passage geometries, material systems, and joining processes that will produce long-life hydrogen-cooled structures for scramjet applications. Tests were performed to establish basic material properties, and samples constructed and evaluated to substantiate fabrication processes and inspection techniques. Results of the study show that the basic goal of increasing the life of hydrogen-cooled structures two orders of magnitude relative to that of the Hypersonic Research Engine can be reached with available means. Estimated life is 19000 cycles for the channels and 16000 cycles for pin-fin coolant passage configurations using Nickel 201. Additional research is required to establish the fatigue characteristics of dissimilar-metal coolant passages (Nickel 201/Inconel 718) and to investigate the embrittling effects of the hydrogen coolant.

  15. Shuttle active thermal control system development testing. Volume 5: Integrated radiator/expendable cooling system tests

    NASA Technical Reports Server (NTRS)

    Scheps, P. B.

    1974-01-01

    Tests were conducted to gather data on a space shuttle active control system (ATCS) incorporating both radiators and an expendable cooling device to provide vehicle heat removal. Two systems were tested and design information was provided for both nominal and limit conditions. The tests verified the concept that an integrated radiator/expendable cooling system can adequately maintain desired water quantities while responding to variations in heat loads and environments. In addition, the need for duct heating was demonstrated, while exhaust nozzle heating was also shown to be unnecessary.

  16. Current Status of Joint AFRL/NASA Microgravity Spray Cooling Research Activities

    NASA Technical Reports Server (NTRS)

    Michalak, Travis; Yerkes,Kirk; McQuillen, John; Golliher, Eric

    2004-01-01

    The Air Force Research Lab and the NASA Glenn Research Center are cooperatively examining spray cooling in a low and a variable gravity environment by conducting experiments principally aboard the NASA Reduced Gravity Aircraft. The objective of these research activities is to examine an effective high-heat flux, high-power thermal management technology using spray cooling for both aircraft and space-based platforms. Previous studies have demonstrated that two phase heat transfer and fluid management are issues that need to be examined. This effort has obtained preliminary results which confirm these concerns. More research is planned.

  17. Structure, branching ratios, and a laser-cooling scheme for the 138BaF molecule

    NASA Astrophysics Data System (ADS)

    Chen, Tao; Bu, Wenhao; Yan, Bo

    2016-12-01

    For laser-cooling considerations, we have theoretically investigated the electronic, rovibrational, and hyperfine structures of the BaF molecule. The highly diagonal Franck-Condon factors and the branching ratios for all possible transitions within the lowest-lying four electronic states have also been calculated. Meanwhile, the mixing between the metastable A'2Δ and A2Π states and, further, the lifetime of the Δ state have been estimated since the loss procedure via the Δ state might fatally break the main quasicycling Σ -Π transition for cooling and trapping. The resultant hyperfine splittings of each rovibrational state in the X2Σ+ state provide benchmarks for sideband modulations of the cooling and repumping lasers and the remixing microwaves to address all necessary levels. The calculated Zeeman shift and g factors for both X and A states serve as benchmarks for selection of the trapping laser polarizations. Our study paves the way for future laser cooling and magneto-optical trapping of the BaF molecule.

  18. Continuous sorption cooling in activated carbon-nitrogen system using metal foam as regenerator

    NASA Astrophysics Data System (ADS)

    Ghosh, Indranil

    2017-02-01

    In compressor driven solid sorption process, cooling obtained from a desorbing bed (equivalent to an evaporator), is intermittent in nature. Intermittency can be avoided using multiple adsorbent columns. However, connecting a desorbing bed to heat source and adsorbing beds to heat sink in alternate cycles enhances operational complexity and constructional disadvantages. In a recent development, it has been seen that rapid and successive pressurization and depressurization of an adsorbent (solid) bed with adsorbate (gas) creates temperature differential across the column length. The presence of an orifice at the end opposite to gas entrance enhances the temperature gradient. By connecting the hot end to heat sink and the cold end to heat source permanently, one can substantially reduce the operational hazards associated with the intermittent sorption cooling processes. More recently, it has seen that the introduction of a regenerator in the process makes the cooling process more effective. Though the proposed sorption cooling process apparently looks similar to orifice type ‘pulse tube’ cooler, the former is intrinsically different than the other. In the present manuscript, experimental sorption cooling studies using of metal foam as regenerator has been discussed. Tests have been conducted near room temperature in activated carbon-nitrogen system.

  19. Active cooling in traumatic brain-injured patients: a questionable therapy?

    PubMed

    Grände, P-O; Reinstrup, P; Romner, B

    2009-11-01

    Hypothermia is shown to be beneficial for the outcome after a transient global brain ischaemia through its neuroprotective effect. Whether this is also the case after focal ischaemia, such as following a severe traumatic brain injury (TBI), has been investigated in numerous studies, some of which have shown a tendency towards an improved outcome, whereas others have not been able to demonstrate any beneficial effect. A Cochrane report concluded that the majority of the trials that have already been published have been of low quality, with unclear allocation concealment. If only high-quality trials are considered, TBI patients treated with active cooling were more likely to die, a conclusion supported by a recent high-quality Canadian trial on children. Still, there is a belief that a modified protocol with a shorter time from the accident to the start of active cooling, longer cooling and rewarming time and better control of blood pressure and intracranial pressure would be beneficial for TBI patients. This belief has led to the instigation of new trials in adults and in children, including these types of protocol adjustments. The present review provides a short summary of our present knowledge of the use of active cooling in TBI patients, and presents some tentative explanations as to why active cooling has not been shown to be effective for outcome after TBI. We focus particularly on the compromised circulation of the penumbra zone, which may be further reduced by the stress caused by the difference in thermostat and body temperature and by the hypothermia-induced more frequent use of vasoconstrictors, and by the increased risk of contusional bleedings under hypothermia. We suggest that high fever should be reduced pharmacologically.

  20. The cast structure of a 7075 alloy produced by a water-cooling centrifugal casting method

    SciTech Connect

    Yeh, J.W. . Dept. of Materials Science and Engineering); Jong, S.H.

    1994-03-01

    A water-cooling centrifugal casting method was applied to cast the 7075 Al alloy to generate a much finer cast structure than that produced by conventional ingot casting methods. The effects of casting parameters, i.e., rotation speed, pouring temperature, water flow, and grain refiner, on casting structure were systematically studied so that the optimum casting condition and the solidification mechanism could be established. The typical cast structure along the thickness direction of a cast ring could be divided into four equiaxed zones, including the chill zone which is in contact with the mold wall. All zones have their characteristic grain size, morphology, and relative thickness, which are all dependent on the casting condition. The optimum casting condition yielding the finest structure available was found to be 3,000 rpm, 650 C, and sufficient water cooling. A uniform portion occupying 90 pct of the whole thickness and having a grain size of 17 [mu]m could be achieved under such a casting condition. When a grain refiner was added, the whole ring became further concentrated with grains of fine structure. A mechanism concerning the overall effects of rapid solidification, turbulent flow, and centrifugal force has been proposed for the present casting method and might explain the zone-structure formation and the effects of the casting parameters on microstructural features.

  1. RF, Thermal and Structural Analysis of the 201.25 MHz MuonIonization Cooling Cavity

    SciTech Connect

    Virostek, S.; Li, D.

    2005-05-10

    A finite element analysis has been carried out to characterize the RF, thermal and structural behavior of the prototype 201.25 MHz cavity for a muon ionization cooling channel. A single ANSYS model has been developed to perform all of the calculations in a multi-step process. The high-gradient closed-cell cavity is currently being fabricated for the MICE (international Muon Ionization Cooling Experiment) and MUCOOL experiments. The 1200 mm diameter cavity is constructed of 6 mm thick copper sheet and incorporates a rounded pillbox-like profile with an open beam iris terminated by 420 mm diameter, 0.38 mm thick curved beryllium foils. Tuning is accomplished through elastic deformation of the cavity, and cooling is provided by external water passages. Details of the analysis methodology will be presented including a description of the ANSYS macro that computes the heat loads from the RF solution and applies them directly to the thermal model. The process and results of a calculation to determine the resulting frequency shift due to thermal and structural distortion of the cavity will also be presented.

  2. The structure of shocks with thermal conduction and radiative cooling. [in astrophysical plasmas

    NASA Technical Reports Server (NTRS)

    Lacey, Cedric G.

    1988-01-01

    A general analysis is presented of the structure of a steady state, plane-parallel shock wave in which both thermal conduction and radiative cooling are important. The fluid is assumed to have a perfect-gas equation of state, with radiative cooling a function only of its temperature and density. Conduction in both diffusive and saturated regimes is treated. For the case of a strong shock, with conductivity and cooling function varying as power laws in temperature, approximate analytic solutions describing the shock wave are derived. For a plasma of solar composition, conduction is found to have a significant effect on the shock temperature and overall thickness of the postshock layer only for shock velocities greater than about 30,000 km/s, corresponding to shock temperatures greater than about 10 to the 10th K, but it affects the local structure of parts of the shock wave at much lower velocities. The effects of conduction are greatly enhanced if the heavy-element abundance is increased.

  3. Active versus passive cooling during work in warm environments while wearing firefighting protective clothing.

    PubMed

    Selkirk, G A; McLellan, T M; Wong, J

    2004-08-01

    This study examined whether active or passive cooling during intermittent work reduced the heat strain associated with wearing firefighting protective clothing (FPC) and self-contained breathing apparatus (SCBA) in the heat (35 degrees Celsius, 50% relative humidity). Fifteen male Toronto firefighters participated in the heat-stress trials. Subjects walked at 4.5 km.h(-1) with 0% elevation on an intermittent work (50 min) and rest (30 min) schedule. Work continued until rectal temperature (T(re)) reached 39.5 degrees Celsius, or heart rate (HR) reached 95% of maximum or exhaustion. One of three cooling strategies, forearm submersion (FS), mister (M), and passive cooling (PC) were employed during the rest phases. Tolerance time (TT) and total work time (WT) (min) were significantly increased during FS (178.7 +/- 13.0 and 124.7 +/- 7.94, respectively) and M (139.1 +/- 8.28 and 95.1 +/- 4.96, respectively), compared with PC (108.0 +/- 3.59 and 78.0 +/- 3.59). Furthermore, TT and WT were significantly greater in FS compared with M. Rates of T(re) increase, HR and T-(sk) were significantly lower during active compared with passive cooling. In addition, HR and T(re) values in FS were significantly lower compared with M after the first rest phase. During the first rest phase, T(re) dropped significantly during FS (approximately 0.4 degree Celsius) compared with M (approximately 0.08 degree Celsius) while PC increased (approximately 0.2 degree Celsius). By the end of the second rest period T(re) was 0.9 degree Celsius lower in FS compared with M. The current findings suggest that there is a definite advantage when utilizing forearm submersion compared with other methods of active or passive cooling while wearing FPC and SCBA in the heat.

  4. Structural transformation of Au-Pd bimetallic nanoclusters on thermal heating and cooling: a dynamic analysis.

    PubMed

    Liu, H B; Pal, U; Perez, R; Ascencio, J A

    2006-03-23

    Classical molecular dynamics simulation is used for structural thermodynamic and dynamic analysis of Au-Pd bimetallic clusters. It is observed that the Pd-core/Au-shell structure is the most stable, and can be formed through annealing of other structures such as Au-core/Pd-shell, eutecticlike, or solid solution. Depending on the starting temperature and initial composition, three-layer icosahedral nanorod, face-centered cubic (fcc) nanorod, and fcc cluster can be obtained on slow cooling. The three-layer icosahedral nanorod structure is not as stable as the Pd-core/Au-shell decahedron; however it is more stable than the solid-solution decahedron structure up to 400 K. Our findings provide valuable insight into catalysis using Au-Pd and other similar bimetallic clusters.

  5. Cooling rate dependence of structural order in Al90Sm10 metallic glass

    DOE PAGES

    Sun, Yang; Zhang, Yue; Zhang, Feng; ...

    2016-07-07

    Here, the atomic structure of Al90Sm10 metallic glass is studied using molecular dynamics simulations. By performing a long sub-Tg annealing, we developed a glass model closer to the experiments than the models prepared by continuous cooling. Using the cluster alignment method, we found that “3661” cluster is the dominating short-range order in the glass samples. The connection and arrangement of “3661” clusters, which define the medium-range order in the system, are enhanced significantly in the sub-Tg annealed sample as compared with the fast cooled glass samples. Unlike some strong binary glass formers such as Cu64.5Zr35.5, the clusters representing the short-rangemore » order do not form an interconnected interpenetrating network in Al90Sm10, which has only marginal glass formability.« less

  6. Volume and structural analysis of super-cooled water under high pressure

    NASA Astrophysics Data System (ADS)

    Duki, Solomon F.; Tsige, Mesfin

    2012-02-01

    Motivated by recent experimental study of super-cooled water at high pressure [1], we performed atomistic molecular dynamic simulations study on bulk water molecules at isothermal-isobaric ensemble. These simulations are performed at temperatures that range from 40 K to 380 K using two different cooling rates, 10K/ns and 10K/5ns, and pressure that ranges from 1atm to 10000 atm. Our analysis for the variation of the volume of the bulk sample against temperature indicates a downward concave shape for pressures above certain values, as reported in [1]. The same downward concave behavior is observed at high pressure on the mean-squared-displacements (MSD) of the water molecules when the MSD is plotted against time. To get further insight on the effect of the pressure on the sample we have also performed a structural analysis of the sample.[4pt] [1] O. Mishima, J. Chem. Phys. 133, 144503 (2010);

  7. Sarcosine and betaine crystals upon cooling: structural motifs unstable at high pressure become stable at low temperatures.

    PubMed

    Kapustin, E A; Minkov, V S; Boldyreva, E V

    2015-02-07

    The crystal structures of N-methyl derivatives of the simplest amino acid glycine, namely sarcosine (C3H7NO2) and betaine (C5H11NO2), were studied upon cooling by single-crystal X-ray diffraction and single-crystal polarized Raman spectroscopy. The effects of decreasing temperature and increasing hydrostatic pressure on the crystal structures were compared. In particular, we have studied the behavior upon cooling of those structural motifs in the crystals, which are involved in structural rearrangement during pressure-induced phase transitions. In contrast to their high sensitivity to hydrostatic compression, the crystals of both sarcosine and betaine are stable to cooling down to 5 K. Similarly to most α-amino acids, the crystal structures of the two compounds are most rigid upon cooling in the direction of the main structural motif, namely head-to-tail chains (linked via the strongest N-H···O hydrogen bonds and dipole-dipole interactions in the case of sarcosine, or exclusively by dipole-dipole interactions in the case of betaine). The anisotropy of linear strain in betaine does not differ much upon cooling and on hydrostatic compression, whereas this is not the case for sarcosine. Although the interactions between certain structural motifs in sarcosine and betaine weaken as a result of phase transitions induced by pressure, the same interactions strengthen when volume reduction results from cooling.

  8. Identification of Structural Motifs of Imidazolium Based Ionic Liquids from Jet-Cooled Infrared Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Young, Justin W.; Booth, Ryan S.; Annesley, Christopher; Stearns, Jaime A.

    2016-06-01

    Highly variable and potentially revolutionary, ionic liquids (IL) are a class of molecules with potential for numerous Air Force applications such as satellite propulsion, but the complex nature of IL structure and intermolecular interactions makes it difficult to adequately predict structure-property relationships in order to make new IL-based technology a reality. For example, methylation of imidazolium ionic liquids leads to a substantial increase in viscosity but the underlying physical mechanism is not understood. In addition the role of hydrogen bonding in ILs, especially its relationship to macroscopic properties, is a matter of ongoing research. Here, structural motifs are identified from jet-cooled infrared spectra of different imidazolium based ionic liquids, such as 1-ethyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl)imide. Measurements of the C-H stretches indicate three structural families present in the gas phase.

  9. Spectral characteristics of heterocyclic compounds with a chain structure, cooled in an ultrasonic jet

    NASA Astrophysics Data System (ADS)

    Povedailo, V. A.; Yakovlev, D. L.

    2006-11-01

    We have recorded the fluorescence excitation spectra of three heterocyclic compounds with a chain structure [BPO (2-phenyl-5-(4-diphenylyl)oxazole), POPOP (1,4-di[2-(5-phenyloxazolyl)]benzene, and TOPOT (1,4-di[2-(5-n-tolyloxazolyl)]benzene] and the fluorescence spectra of POPOP, under conditions where the molecules were cooled in an ultrasonic helium jet. A line structure is observed in the spectra of POPOP and TOPOT; for the BPO molecules, whose configuration changes considerably during electronic excitation, vibrational structure is apparent only in the low-frequency region of the excitation spectrum, and a diffuse spectrum is recorded starting from ν 0 0 + 200 cm-1. For all the compounds, in the spectra we recorded vibrations with frequencies up to 100 cm-1, arising due to the flexibility of the molecular structure. The rotational contours of the lines for the electronic and vibronic transitions of the POPOP molecules (Trot = 10.5 K) and TOPOT molecules (Trot = 15 K) are structureless and bell-shaped. The degree of polarization of the fluorescence Pfl for the jet-cooled POPOP molecules for excitation of vibrations along the absorption band up to 2000 cm-1 above ν 0 0 is practically constant (˜8.4%) and matches Pfl for high-temperature vapors.

  10. Active cooling-based surface confinement system for thermal soil treatment

    DOEpatents

    Aines, Roger D.; Newmark, Robin L.

    1997-01-01

    A thermal barrier is disclosed for surface confinement with active cooling to control subsurface pressures during thermal remediation of shallow (5-20 feet) underground contaminants. If steam injection is used for underground heating, the actively cooled thermal barrier allows the steam to be injected into soil at pressures much higher (20-60 psi) than the confining strength of the soil, while preventing steam breakthrough. The rising steam is condensed to liquid water at the thermal barrier-ground surface interface. The rapid temperature drop forced by the thermal barrier drops the subsurface pressure to below atmospheric pressure. The steam and contaminant vapors are contained by the thermal blanket, which can be made of a variety of materials such as steel plates, concrete slabs, membranes, fabric bags, or rubber bladders.

  11. Active cooling-based surface confinement system for thermal soil treatment

    DOEpatents

    Aines, R.D.; Newmark, R.L.

    1997-10-28

    A thermal barrier is disclosed for surface confinement with active cooling to control subsurface pressures during thermal remediation of shallow (5-20 feet) underground contaminants. If steam injection is used for underground heating, the actively cooled thermal barrier allows the steam to be injected into soil at pressures much higher (20-60 psi) than the confining strength of the soil, while preventing steam breakthrough. The rising steam is condensed to liquid water at the thermal barrier-ground surface interface. The rapid temperature drop forced by the thermal barrier drops the subsurface pressure to below atmospheric pressure. The steam and contaminant vapors are contained by the thermal blanket, which can be made of a variety of materials such as steel plates, concrete slabs, membranes, fabric bags, or rubber bladders. 1 fig.

  12. National commercial solar heating and cooling demonstration: purposes, program activities, and implications for future programs

    SciTech Connect

    Koontz, R.; Genest, M.; Bryant, B.

    1980-05-01

    The Solar Heating and Cooling Demonstration Act of 1974 created a set of activities to demonstrate the potential use of solar heating within a three-year period and of combined solar heating and cooling within a five-year period. This study assesses the Commercial Demonstration Program portion of the activity in terms of its stated goals and objectives. The primary data base was DOE contractor reports on commercial demonstration projects. It was concluded that the program did not provide data to support a positive decision for the immediate construction or purchase of commercial solar systems. However, the program may have contributed to other goals in the subsequent legislation; i.e., research and development information, stimulation of the solar industry, and more informed policy decisions.

  13. CONNECTING STAR FORMATION QUENCHING WITH GALAXY STRUCTURE AND SUPERMASSIVE BLACK HOLES THROUGH GRAVITATIONAL HEATING OF COOLING FLOWS

    SciTech Connect

    Guo, Fulai

    2014-12-20

    Recent observations suggested that star formation quenching in galaxies is related to galaxy structure. Here we propose a new mechanism to explain the physical origin of this correlation. We assume that while quenching is maintained in quiescent galaxies by a feedback mechanism, cooling flows in the hot halo gas can still develop intermittently. We study cooling flows in a large suite of around 90 hydrodynamic simulations of an isolated galaxy group, and find that the flow development depends significantly on the gravitational potential well in the central galaxy. If the galaxy's gravity is not strong enough, cooling flows result in a central cooling catastrophe, supplying cold gas and feeding star formation to galactic bulges. When the bulge grows prominent enough, compressional heating starts to offset radiative cooling and maintains cooling flows in a long-term hot mode without producing a cooling catastrophe. Our model thus describes a self-limited growth channel for galaxy bulges and naturally explains the connection between quenching and bulge prominence. In particular, we explicitly demonstrate that M{sub ∗}/R{sub eff}{sup 1.5} is a good structural predictor of quenching. We further find that the gravity from the central supermassive black hole also affects the bimodal fate of cooling flows, and we predict a more general quenching predictor to be M{sub bh}{sup 1.6}M{sub ∗}/R{sub eff}{sup 1.5}, which may be tested in future observational studies.

  14. Active cooling for downhole instrumentation: design criteria and conceptual design summary

    SciTech Connect

    Bennett, G.A.

    1986-05-01

    This report summarizes the results of a literature survey that describes successful tests of geophysical instruments and their thermal protection systems. The conditions to which an instrument is subjected are formulated into relevant thermal and mechanical design criteria that have proved useful for improving passive thermal protection systems and selecting the preliminary feasibility of active refrigeration systems. A brief summary of the results of a series of conceptual designs on seven different active refrigeration systems is given. The systems are ranked according to feasibility for use in downhole active cooling applications.

  15. Grueneberg Glomeruli in the Olfactory Bulb are Activated by Odorants and Cool Temperature.

    PubMed

    Bumbalo, Rosolino; Lieber, Marilena; Schroeder, Lisa; Polat, Yasemin; Breer, Heinz; Fleischer, Joerg

    2016-08-03

    Neurons of the Grueneberg ganglion respond to cool temperatures as well as to distinct odorants and extend axonal processes to the olfactory bulb of the brain. Analyses of transgenic mice, in which Grueneberg ganglion neurons and their axons are labeled, revealed that these axons innervated nine distinct glomeruli distributed in a characteristic topographical pattern in dorsal, lateral, ventral, and medial regions of rather posterior areas in the bulb. To assess activation of these glomeruli (hereinafter designated as Grueneberg glomeruli) upon stimulation of Grueneberg ganglion neurons, mice were exposed to the odorant 2,3-dimethylpyrazine (2,3-DMP) and the expression of the activity-dependent marker c-Fos in juxtaglomerular cells of the relevant glomeruli was monitored. It was found that all of these glomeruli were activated, irrespective of their localization in the bulb. To verify that the activation of juxtaglomerular cells in Grueneberg glomeruli was indeed based on stimulation of Grueneberg ganglion neurons, the 2,3-DMP-induced responses in these glomeruli were investigated in mice lacking the cyclic nucleotide-gated channel CNGA3 which is critical for chemo- and thermosensory signal transduction in Grueneberg ganglion neurons. This approach revealed that elimination of CNGA3 led to a reduction of the odorant-induced activity in Grueneberg glomeruli, indicating that the activation of these glomeruli is based on a preceding stimulation of the Grueneberg ganglion. Analyzing whether Grueneberg glomeruli in the bulb might also process thermosensory information, it was found that upon exposure to coolness, Grueneberg glomeruli were activated. Investigating mice lacking CNGA3, the activation of these glomeruli by cool temperatures was attenuated.

  16. Rapid cooling rates at an active mid-ocean ridge from zircon thermochronology

    USGS Publications Warehouse

    Schmitt, Axel K.; Perfit, Michael R.; Rubin, Kenneth H.; Stockli, Daniel F.; Smith, Matthew C.; Cotsonika, Laurie A.; Zellmer, Georg F.; Ridley, W. Ian

    2011-01-01

    Oceanic spreading ridges are Earth's most productive crust generating environment, but mechanisms and rates of crustal accretion and heat loss are debated. Existing observations on cooling rates are ambiguous regarding the prevalence of conductive vs. convective cooling of lower oceanic crust. Here, we report the discovery and dating of zircon in mid-ocean ridge dacite lavas that constrain magmatic differentiation and cooling rates at an active spreading center. Dacitic lavas erupted on the southern Cleft segment of the Juan de Fuca ridge, an intermediate-rate spreading center, near the intersection with the Blanco transform fault. Their U–Th zircon crystallization ages (29.3-4.6+4.8 ka; 1δ standard error s.e.) overlap with the (U–Th)/He zircon eruption age (32.7 ± 1.6 ka) within uncertainty. Based on similar 238U-230Th disequilibria between southern Cleft dacite glass separates and young mid-ocean ridge basalt (MORB) erupted nearby, differentiation must have occurred rapidly, within ~ 10–20 ka at most. Ti-in-zircon thermometry indicates crystallization at 850–900 °C and pressures > 70–150 MPa are calculated from H2O solubility models. These time-temperature constraints translate into a magma cooling rate of ~ 2 × 10-2 °C/a. This rate is at least one order-of-magnitude faster than those calculated for zircon-bearing plutonic rocks from slow spreading ridges. Such short intervals for differentiation and cooling can only be resolved through uranium-series (238U–230Th) decay in young lavas, and are best explained by dissipating heat convectively at high crustal permeability.

  17. Mathematical modeling of the thermal and hydrodynamic structure of the cooling reservoir

    NASA Astrophysics Data System (ADS)

    Saminskiy, G.; Debolskaya, E.

    2012-04-01

    Hydrothermal conditions of the cooling reservoir is determined by the heat and mass transfer from the water surface to the atmosphere and the processes of heat transfer directly in the water mass of the reservoir. As the capacity of power plants, the corresponding increase in the volume of heated water and the use of deep lakes and reservoirs as coolers there is a need to develop new, more accurate, and the application of existing methods for the numerical simulation. In calculating the hydrothermal regime it must take into account the effect of wind, density (buoyancy) forces, and other data of the cooling reservoir. In addition to solving practical problems it is important to know not only the magnitude of the average temperature, but also its area and depth distribution. A successful solution can be achieved through mathematical modeling of general systems of equations of transport processes and the correct formulation of the problem, based on appropriate initial data. The purpose of the work is application of software package GETM for simulating the hydrothermal regime of cooling reservoir with an estimate of three-dimensional structure of transfer processes, the effects of wind, the friction of the water surface. Three-dimensional models are rarely applied, especially for far-field problems. If such models are required, experts in the field must develop and apply them. Primary physical processes included are surface heat transfer, short-wave and long-wave radiation and penetration, convective mixing, wind and flow induced mixing, entrainment of ambient water by pumped-storage inflows, inflow density stratification as impacted by temperature and dissolved and suspended solids. The model forcing data consists of the system bathymetry developed into the model grid; the boundary condition flow and temperature; the tributary and flow and temperature; and the system meteorology. Ivankovskoe reservoir belongs to the reservoirs of valley type (Tver region, Russia). It

  18. Mitigation of Autoignition Due to Premixing in a Hypervelocity Flow Using Active Wall Cooling

    NASA Technical Reports Server (NTRS)

    Axdahl, Erik; Kumar, Ajay; Wilhite, Alan

    2013-01-01

    Preinjection of fuel on the forebody of an airbreathing vehicle is a proposed method to gain access to hypervelocity flight Mach numbers. However, this creates the possibility of autoignition either near the wall or in the core of the flow, thereby consuming fuel prematurely as well as increasing the amount of pressure drag on the vehicle. The computational fluid dynamics code VULCAN was used to conduct three dimensional simulations of the reacting flow in the vicinity of hydrogen injectors on a flat plate at conditions relevant to a Mach 12 notional flight vehicle forebody to determine the location where autoignition occurs. Active wall cooling strategies were formulated and simulated in response to regions of autoignition. It was found that tangential film cooling using hydrogen or helium were both able to nearly or completely eliminate wall autoignition in the flow domain of interest.

  19. Micro free-flow IEF enhanced by active cooling and functionalized gels.

    PubMed

    Albrecht, Jacob W; Jensen, Klavs F

    2006-12-01

    Rapid free-flow IEF is achieved in a microfluidic device by separating the electrodes from the focusing region with porous buffer regions. Moving the electrodes outside enables the use of large electric fields without the detrimental effects of bubble formation in the active region. The anode and cathode porous buffer regions, which are formed by acrylamide functionalized with immobilized pH groups, allow ion transport while providing buffering capacity. Thermoelectric cooling mitigates the effects of Joule heating on sample focusing at high field strengths (approximately 500 V/cm). This localized cooling was observed to increase device performance. Rapid focusing of low-molecular-weight p/ markers and Protein G-mouse IgG complexes demonstrate the versatility of the technique. Simulations provide insight into and predict device performance based on a well-defined sample composition.

  20. Transport and deposition of activation products in a helium cooled fusion power plant

    SciTech Connect

    Bickford, W.E.

    1980-09-01

    The transport and deposition of neutron activation products in a helium cooled tokamak fusion power plant are investigated. Stainless steel is used as coolant channel material for a helium/steam system. The important gamma emitting nuclides /sup 56/Mn, /sup 54/Mn, /sup 57/Co, /sup 58/Co, /sup 60/Co, /sup 51/Cr, and /sup 99/Mo are considered. The dominant release mechanism identified is direct daughter recoil emission from (n,x) type reactions. Corrosion and evaporation are discussed. The radionuclide inventory released by these mechanisms is predicted to exceed 1 x 10/sup 4/ Ci for a reference reactor design after only several days of operation, and approach 3.5 x 10/sup 4/ Ci in equilibrium. A mass transport model is then used to predict the deposition pattern of this inventory in the reactor cooling system.

  1. Observations of the effect of wind on the cooling of active lava flows

    USGS Publications Warehouse

    Keszthelyi, L.; Harris, A.J.L.; Dehn, J.

    2003-01-01

    We present the first direct observations of the cooling of active lava flows by the wind. We confirm that atmospheric convective cooling processes (i.e., the wind) dominate heat loss over the lifetime of a typical pahochoe lava flow. In fact, the heat extracted by convection is greater than predicted, especially at wind speeds less than 5 m/s and surface temperatures less than 400??C. We currently estimate that the atmospheric heat transfer coefficient is about 45-50 W m-2 K-1 for a 10 m/s wind and a surface temperature ???500??C. Further field experiments and theoretical studies should expand these results to a broader range of surface temperatures and wind speeds.

  2. Cooling water canal improvements to correct structural failures and control Asian clams

    SciTech Connect

    England, W.; Snow, R.E.; Palmer, E.C.

    1995-10-01

    Expansive soils destroyed the floor and impacted the roof support columns of a 600-foot-long concrete cooling water intake canal at the two unit, 700-MW Decker Creek Power Plant in Austin, Texas. These movements exposed clay and silt soils in the canal bottom and provided a habitat for a thriving Asian Clam community which caused operational problems in the plant including unplanned outages. Evaluations were performed to address the structural damages, characterize the clam habitat, and identify concepts to remediate the problem conditions. The various concepts evaluated to eliminate the difficulties are discussed in this paper as well as the basis for selection of the remedial concept. The selected remedial concept consisted of replacing the concrete canal structure with large diameter concrete pipes. The paper also discusses the construction sequence to accomplish the work within a limited outage period.

  3. Modeling Active Galactic Nucleus Feedback in Cool-core Clusters: The Formation of Cold Clumps

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Bryan, Greg L.

    2014-07-01

    We perform high-resolution (15-30 pc) adaptive mesh simulations to study the impact of momentum-driven active galactic nucleus (AGN) feedback in cool-core clusters, focusing in this paper on the formation of cold clumps. The feedback is jet-driven with an energy determined by the amount of cold gas within 500 pc of the super-massive black hole. When the intracluster medium in the core of the cluster becomes marginally stable to radiative cooling, with the thermal instability to the free-fall timescale ratio t TI/t ff < 3-10, cold clumps of gas start to form along the propagation direction of the AGN jets. By tracing the particles in the simulations, we find that these cold clumps originate from low entropy (but still hot) gas that is accelerated by the jet to outward radial velocities of a few hundred km s-1. This gas is out of hydrostatic equilibrium and so can cool. The clumps then grow larger as they decelerate and fall toward the center of the cluster, eventually being accreted onto the super-massive black hole. The general morphology, spatial distribution, and estimated Hα morphology of the clumps are in reasonable agreement with observations, although we do not fully replicate the filamentary morphology of the clumps seen in the observations, probably due to missing physics.

  4. Modeling active galactic nucleus feedback in cool-core clusters: The formation of cold clumps

    SciTech Connect

    Li, Yuan; Bryan, Greg L.

    2014-07-10

    We perform high-resolution (15-30 pc) adaptive mesh simulations to study the impact of momentum-driven active galactic nucleus (AGN) feedback in cool-core clusters, focusing in this paper on the formation of cold clumps. The feedback is jet-driven with an energy determined by the amount of cold gas within 500 pc of the super-massive black hole. When the intracluster medium in the core of the cluster becomes marginally stable to radiative cooling, with the thermal instability to the free-fall timescale ratio t{sub TI}/t{sub ff} < 3-10, cold clumps of gas start to form along the propagation direction of the AGN jets. By tracing the particles in the simulations, we find that these cold clumps originate from low entropy (but still hot) gas that is accelerated by the jet to outward radial velocities of a few hundred km s{sup –1}. This gas is out of hydrostatic equilibrium and so can cool. The clumps then grow larger as they decelerate and fall toward the center of the cluster, eventually being accreted onto the super-massive black hole. The general morphology, spatial distribution, and estimated Hα morphology of the clumps are in reasonable agreement with observations, although we do not fully replicate the filamentary morphology of the clumps seen in the observations, probably due to missing physics.

  5. The Cooling History and Structure of the Ordinary Chondrite Parent Bodies

    NASA Technical Reports Server (NTRS)

    Benoit, P. H.; Sears, D. W. G.

    1996-01-01

    Most major meteorite classes exhibit significant ranges of metamorphism. The effects of metamorphism have been extensively characterized, but the heat source(s) and the metamorphic environment are unknown. Proposed beat sources include Al-26, Fe-60, electromagnetic induction, and impact. It is typically assumed that metamorphism occurred in parent bodies of some sort, but it uncertain whether these bodies were highly structured ("onion skins") or were chaotic mixes of material ("rubble piles"). The lack of simple trends of metallographic cooling rates with petrologic type has been considered supportive of both concepts. In this study, we use induced thermoluminescence (TL) as an indicator of thermal history. The TL of ordinary chondrites is produced by sodic feldspar, and the induced TL peak temperature is related to its crystallographic order/disorder. Ordered feldspar has TL peak temperatures of approx. 120 C, and disordered feldspar has TL peak temperatures of approx. 220 C. While ordered feldspar can be easily disordered in the laboratory by heating above 650 C and is easily quenched in the disordered form, producing ordered feldspar requires cooling at geologic cooling rates. We have measured the induced TL properties of 101 equilibrated ordinary chondrites, including 49 H, 29 L, and 23 LL chondrites. For the H chondrites there is an apparent trend of decreasing induced TL peak temperature with increasing petrologic type. H4 chondrites exhibit a tight range of TL peak temperatures, 190 C - 200 C, while H6 chondrites exhibit TL peak temperatures between 180 C and 190 C. H5 chondrites cover the range between H4 and H6, and also extend up to 210 C. Similar results are obtained for LL chondfiles and most L6 chondrites have lower induced TL peak temperatures than L5 chondrites.

  6. EVIDENCE FOR WIDESPREAD COOLING IN AN ACTIVE REGION OBSERVED WITH THE SDO ATMOSPHERIC IMAGING ASSEMBLY

    SciTech Connect

    Viall, Nicholeen M.; Klimchuk, James A.

    2012-07-01

    A well-known behavior of EUV light curves of discrete coronal loops is that the peak intensities of cooler channels or spectral lines are reached at progressively later times than hotter channels. This time lag is understood to be the result of hot coronal loop plasma cooling through these lower respective temperatures. However, loops typically comprise only a minority of the total emission in active regions (ARs). Is this cooling pattern a common property of AR coronal plasma, or does it only occur in unique circumstances, locations, and times? The new Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) data provide a wonderful opportunity to answer this question systematically for an entire AR. We measure the time lag between pairs of SDO/AIA EUV channels using 24 hr of images of AR 11082 observed on 2010 June 19. We find that there is a time-lag signal consistent with cooling plasma, just as is usually found for loops, throughout the AR including the diffuse emission between loops for the entire 24 hr duration. The pattern persists consistently for all channel pairs and choice of window length within the 24 hr time period, giving us confidence that the plasma is cooling from temperatures of greater than 3 MK, and sometimes exceeding 7 MK, down to temperatures lower than {approx}0.8 MK. This suggests that the bulk of the emitting coronal plasma in this AR is not steady; rather, it is dynamic and constantly evolving. These measurements provide crucial constraints on any model which seeks to describe coronal heating.

  7. Effect of Secondary Cooling Conditions on Solidification Structure and Central Macrosegregation in Continuously Cast High-Carbon Rectangular Billet

    NASA Astrophysics Data System (ADS)

    Zeng, Jie; Chen, Weiqing

    2015-10-01

    Solidification structures of high carbon rectangular billet with a size of 180 mm × 240 mm in different secondary cooling conditions were simulated using cellular automaton-finite element (CAFE) coupling model. The adequacy of the model was compared with the simulated and the actual macrostructures of 82B steel. Effects of the secondary cooling water intensity on solidification structures including the equiaxed grain ratio and the equiaxed grain compactness were discussed. It was shown that the equiaxed grain ratio and the equiaxed grain compactness changed in the opposite direction at different secondary cooling water intensities. Increasing the secondary cooling water intensity from 0.9 or 1.1 to 1.3 L/kg could improve the equiaxed grain compactness and decrease the equiaxed grain ratio. Besides, the industrial test was conducted to investigate the effect of different secondary cooling water intensities on the center carbon macrosegregation of 82B steel. The optimum secondary cooling water intensity was 0.9 L/kg, while the center carbon segregation degree was 1.10. The relationship between solidification structure and center carbon segregation was discussed based on the simulation results and the industrial test.

  8. Thermal-structural analysis of the platelet heat-pipe-cooled leading edge of hypersonic vehicle

    NASA Astrophysics Data System (ADS)

    Hongpeng, Liu; Weiqiang, Liu

    2016-10-01

    One of the main challenges for the hypersonic vehicle is its thermal protection, more specifically, the cooling of its leading edge. To investigate the feasibility of a platelet heat-pipe-cooled leading edge structure, thermal/stress distributions for steady-state flight conditions are calculated numerically. Studies are carried on for IN718/Na, C-103/Na and T-111/Li compatible material combinations of heat pipe under nominal operations and a central heat pipe failure cases, and the influence of wall thickness on the design robustness is also investigated. And the heat transfer limits (the sonic limit, the capillary limit and the boiling limit) are also computed to check the operation of platelet heat pipes. The results indicate that, with a 15 mm leading edge radius and a wall thickness of 0.5 mm, C-103/Na and T-111/Li combinations of heat pipe is capable of withstanding both nominal and failure conditions for Mach 8 and Mach 10 flight respectively.

  9. Inquiry-based Science Activities Using The Infrared Zoo and Infrared Yellowstone Resources at Cool Cosmos

    NASA Astrophysics Data System (ADS)

    Daou, D.; Gauthier, A.

    2003-12-01

    Inquiry-based activities that utilize the Cool Cosmos image galleries have been designed and developed by K12 teachers enrolled in The Invisible Universe Online for Teachers course. The exploration activities integrate the Our Infrared World Gallery (http://coolcosmos.ipac.caltech.edu/image_galleries/our_ir_world_gallery.html) with either the Infrared Zoo gallery (http://coolcosmos.ipac.caltech.edu/image_galleries/ir_zoo/index.html) or the Infrared Yellowstone image http://coolcosmos.ipac.caltech.edu/image_galleries/ir_yellowstone/index.html) and video (http://coolcosmos.ipac.caltech.edu/videos/ir_yellowstone/index.html) galleries. Complete instructor guides have been developed for the activities and will be presented by the authors in poster and CD form. Although the activities are written for middle and highschool learners, they can easily be adapted for college audiences. The Our Infrared World Gallery exploration helps learners think critically about visible light and infrared light as they compare sets of images (IR and visible light) of known objects. For example: by taking a regular photograph of a running faucet, can you tell if it is running hot or cold water? What new information does the IR image give you? The Infrared Zoo activities encourage learners to investigate the differences between warm and cold blooded animals by comparing sets of IR and visible images. In one activity, learners take on the role of a pit viper seeking prey in various desert and woodland settings. The main activities are extended into the real world by discussing and researching industrial, medical, and societal applications of infrared technologies. The Infrared Yellowstone lessons give learners a unique perspective on Yellowstone National Park and it's spectacular geologic and geothermal features. Infrared video technology is highlighted as learners make detailed observations about the visible and infrared views of the natural phenomena. The "Cool Cosmos" EPO activities are

  10. Structurally Efficient Anisotropic Organized Reticulated structures for Cooling of Electronics and Sensors

    DTIC Science & Technology

    2006-08-31

    Shear Modulus, G 27.5GPa Poisson’s Ratio, l 0.306 Yield Stress, cr02 501.1 MPa Ultimate Strength , S, 560.85MPa Elongation, ef 9.7% Reduction in Area...surface area to the structure, as well as the possibility to streamline flow through the array. Furthermore, box lattices have superior strength ...working range over a bare surface. The two major structural concerns are the strength and deformation when a structure is subjected to external

  11. Design and simulation of a novel high-efficiency cooling heat-sink structure using fluid-thermodynamics

    NASA Astrophysics Data System (ADS)

    Hongqi, Jing; Li, Zhong; Yuxi, Ni; Junjie, Zhang; Suping, Liu; Xiaoyu, Ma

    2015-10-01

    A novel high-efficiency cooling mini-channel heat-sink structure has been designed to meet the package technology demands of high power density laser diode array stacks. Thermal and water flowing characteristics have been simulated using the Ansys-Fluent software. Owing to the increased effective cooling area, this mini-channel heat-sink structure has a better cooling effect when compared with the traditional macro-channel heat-sinks. Owing to the lower flow velocity in this novel high efficient cooling structure, the chillers' water-pressure requirement is reduced. Meanwhile, the machining process of this high-efficiency cooling mini-channel heat-sink structure is simple and the cost is relatively low, it also has advantages in terms of high durability and long lifetime. This heat-sink is an ideal choice for the package of high power density laser diode array stacks. Project supported by the Defense Industrial Technology Development Program (No. B1320133033).

  12. A Method Based on Radiative Cooling for Detecting Structural Changes in Undercooled Metallic Liquids

    NASA Technical Reports Server (NTRS)

    Rulison, Aaron J.; Rhim, Won-Kyu

    1995-01-01

    We introduce a structure-sensitive parameter for undercooled melts which can be measured in containerless processing experiments. We have established that the ratio, R(T), of hemispherical total emissivity epsilon(sub T)(T) to constant-pressure specific heat c(sub p)(T) can serve as an indicator which is sensitive to any changes in short range atomic order in undercooled metallic melts. R(T) (triple bonds) epsilon(sub T)(T)/c(sub p)(T) values for nickel, zirconium, and silicon have been obtained using the high temperature electrostatic levitator while the levitated melts were undergoing purely radiative cooling into the deeply undercooled region. R(T) plots for undercooled liquid nickel and zirconium indicate no significant change in short-range structure from their melting temperatures to 15% undercooling. In contrast, liquid silicon shows marked short-range structural changes beginning above its melting temperature and extending throughout the undercooled region. The short-range structure of liquid silicon is related to the highly-directional covalent bonding which characterizes its solid form. The nickel and zirconium data show that epsilon(sub T) varies linearly with T, in support of metal emissivity theories.

  13. Cooling technique

    DOEpatents

    Salamon, Todd R; Vyas, Brijesh; Kota, Krishna; Simon, Elina

    2017-01-31

    An apparatus and a method are provided. Use is made of a wick structure configured to receive a liquid and generate vapor in when such wick structure is heated by heat transferred from heat sources to be cooled off. A vapor channel is provided configured to receive the vapor generated and direct said vapor away from the wick structure. In some embodiments, heat conductors are used to transfer the heat from the heat sources to the liquid in the wick structure.

  14. Pre-irradiation testing of actively cooled Be-Cu divertor modules

    SciTech Connect

    Linke, J.; Duwe, R.; Kuehnlein, W.

    1995-09-01

    A set of neutron irradiation tests is prepared on different plasma facing materials (PFM) candidates and miniaturized components for ITER. Beside beryllium the irradiation program which will be performed in the High Flux Reactor (HFR) in Petten, includes different carbon fiber composites (CFQ) and tungsten alloys. The target values for the neutron irradiation will be 0.5 dpa at temperatures of 350{degrees}C and 700{degrees}C, resp.. The post irradiation examination (PIE) will cover a wide range of mechanical tests; in addition the degradation of thermal conductivity will be investigated. To determine the high heat flux (HHF) performance of actively cooled divertor modules, electron beam tests which simulate the expected heat loads during the operation of ITER, are scheduled in the hot cell electron beam facility JUDITH. These tests on a selection of different actively cooled beryllium-copper and CFC-copper divertor modules are performed before and after neutron irradiation; the pre-irradiation testing is an essential part of the program to quantify the zero-fluence high heat flux performance and to detect defects in the modules, in particular in the brazed joints.

  15. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling.

    PubMed

    Chaudhary, V; Ramanujan, R V

    2016-10-11

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100-xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg(-1). Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications.

  16. Strong variable linear polarization in the cool active star II Peg

    NASA Astrophysics Data System (ADS)

    Rosén, Lisa; Kochukhov, Oleg; Wade, Gregg A.

    2014-08-01

    Magnetic fields of cool active stars are currently studied polarimetrically using only circular polarization observations. This provides limited information about the magnetic field geometry since circular polarization is only sensitive to the line-of-sight component of the magnetic field. Reconstructions of the magnetic field topology will therefore not be completely trustworthy when only circular polarization is used. On the other hand, linear polarization is sensitive to the transverse component of the magnetic field. By including linear polarization in the reconstruction the quality of the reconstructed magnetic map is dramatically improved. For that reason, we wanted to identify cool stars for which linear polarization could be detected at a level sufficient for magnetic imaging. Four active RS CVn binaries, II Peg, HR 1099, IM Peg, and σ Gem were observed with the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope. Mean polarization profiles in all four Stokes parameters were derived using the multi-line technique of least-squares deconvolution (LSD). Not only was linear polarization successfully detected in all four stars in at least one observation, but also, II Peg showed an extraordinarily strong linear polarization signature throughout all observations. This qualifies II Peg as the first promising target for magnetic Doppler imaging in all four Stokes parameters and, at the same time, suggests that other such targets can possibly be identified.

  17. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling

    NASA Astrophysics Data System (ADS)

    Chaudhary, V.; Ramanujan, R. V.

    2016-10-01

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100‑xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg‑1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications.

  18. Elemental abundances in atmospheres of cool dwarfs with solar-like activity

    NASA Astrophysics Data System (ADS)

    Antipova, L. I.; Boyarchuk, A. A.

    2016-01-01

    The elemental abundances in the atmosphere of the red dwarf HD 32147, which belongs to the HR 1614 moving groups, are analyzed. The atmospheric parameters determined from spectroscopic data (the condition of equal abundances for neutral and ionized atoms of a given element) differ considerably from those derived from photometry and parallax data. The abundances of several elements are also anomalous, with the anomaly increasing with decreasing ionization potential. It is concluded that this star is a red dwarf displaying solar-like activity; i.e., having dark (cool) spots on its surface, which may sometimes be considerable in size. Modeling synthetic spectra of stars with cool spots on their surfaces, with the spectral lines consisting of two components formed in media with different temperatures, indicate that the spectroscopic atmospheric parameters derived in such cases are incorrect; this can also explain the observed dependence of the elemental abundances on the corresponding ionization potentials. This leads to the conclusion thatHD32147 is indeed a star with solar-like activity. Several other such stars considered as examples display the same anomalies as those of HD 32147. These modeling results are also valid for Ap and Am stars, and are able to explain short-wavelength observations of the Sun and some stars (the FIP effect).

  19. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling

    PubMed Central

    Chaudhary, V.; Ramanujan, R.V.

    2016-01-01

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100−xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg−1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications. PMID:27725754

  20. Impact of Cubic Pin Finned Surface Structure Geometry upon Spray Cooling Heat Transfer

    NASA Technical Reports Server (NTRS)

    Silk, Eric A.; Kim, Jungho; Kiger, Ken

    2005-01-01

    Experiments were conducted to study the effects of enhanced surface structures on heat flux using spray cooling. The surface enhancements consisted of cubic pin fins machined on the top surface of copper heater blocks. The structure height, pitch, and width were parametrically vaned. Each copper block had a projected cross-sectional area of 2.0 sq cm. Measurements were also obtained on a heater block with a flat surface for baseline comparison purposes. A 2 x 2 nozzle array was used with PF-5060 as the working fluid. Thermal performance data were obtained under nominally degassed (chamber pressure of 41.4 kPa) and gassy conditions (chamber with N2 gas at 100.7 kPa) with a bulk fluid temperature of 20.5 C. Results for both the degassed and gassy cases show that structure width and separation distance have a dominant effect upon the heat transfer for the size ranges used. Cubic pin fin height had little impact upon heat flux. The maximum critical heat flux (CHF) attained for any of the surfaces was 121 W/sq cm, giving an enhancement of 51% relative to the flat surface case under nominally degassed conditions. The gassy case had a maximum CHF of 149 W/sq cm, giving an enhancement of 38% relative to the flat surface case.

  1. Materials Property Profiles for Actively Cooled Panels: An Illustration for Scramjet Applications

    NASA Astrophysics Data System (ADS)

    Vermaak, N.; Valdevit, L.; Evans, A. G.

    2009-04-01

    A scheme for identifying and visualizing the material properties that limit the performance of candidate materials for actively cooled aerospace propulsion components is presented and illustrated for combustor panels for Mach 7 hypersonic vehicles. The method provides a framework for exploring the nonlinear interactions between design and materials optimization. By probing the active constraints along the border of feasible design space, the limiting properties have been elucidated for a representative group of candidate materials. Property vectors that enhance design options have also been determined. For one of the promising candidate alloys (the Ni-based superalloy, INCONEL X-750), the possibilities of reclaiming design space and lowering optimal combustor panel weight by tailoring its strength properties are assessed.

  2. Nondestructive test of brazed cooling tubes of prototype bolometer camera housing using active infrared thermography.

    PubMed

    Tahiliani, Kumudni; Pandya, Santosh P; Pandya, Shwetang; Jha, Ratneshwar; Govindarajan, J

    2011-01-01

    The active infrared thermography technique is used for assessing the brazing quality of an actively cooled bolometer camera housing developed for steady state superconducting tokamak. The housing is a circular pipe, which has circular tubes vacuum brazed on the periphery. A unique method was adopted to monitor the temperature distribution on the internal surface of the pipe. A stainless steel mirror was placed inside the pipe and the reflected IR radiations were viewed using an IR camera. The heat stimulus was given by passing hot water through the tubes and the temperature distribution was monitored during the transient phase. The thermographs showed a significant nonuniformity in the brazing with a contact area of around 51%. The thermography results were compared with the x-ray radiographs and a good match between the two was observed. Benefits of thermography over x-ray radiography testing are emphasized.

  3. Optimisation of concentrating solar cell systems with passive and active cooling

    NASA Astrophysics Data System (ADS)

    Blumenberg, J.

    1983-10-01

    Design considerations for concentrator solar cell arrays for space applications are reviewed, noting the restrictions on total mass that govern system selections. Consideration is given to systems with parabolic mirrors and Si and GaAs solar cells. Passive and active cooling systems for the arrays are discussed, as is the addition of a heat engine with a turbogenerator to utilize part of the waste heat of the cooling cycle. Attention is given to systems orbiting at 0.5, 1, and 3.5 AU from the sun. Flat panels are found to be more suitable for missions near the sun for Si solar cells, while GaAs cells with concentration are preferred to flat panel systems at all distances from the sun. Nuclear turboelectric systems are better than concentrator Si arrays at large distances from the sun, in terms of specific masses of the systems. The addition of a system to use waste heat is judged unfavorable from specific mass factors.

  4. Experiments on FTU with an actively water cooled liquid lithium limiter

    NASA Astrophysics Data System (ADS)

    Mazzitelli, G.; Apicella, M. L.; Apruzzese, G.; Crescenzi, F.; Iannone, F.; Maddaluno, G.; Pericoli-Ridolfini, V.; Roccella, S.; Reale, M.; Viola, B.; Lyublinski, I.; Vertkov, A.

    2015-08-01

    In order to prevent the overheating of the liquid Li surface and the consequent Li evaporation for T > 500 °C, an advanced version of the liquid lithium limiter has been realized and installed on FTU. This new system, named Cooled Lithium Limiter (CLL), has been optimized to demonstrate the lithium limiter capability to sustain thermal loads as high as 10 MW/m2 with up to 5 s of plasma pulse duration. The CLL operates with an actively cooled system with water circulation at the temperature of about 200 °C, for heating lithium up to the melting point and for the heat removal during the plasma discharges. To characterize CLL during discharges, a fast infrared camera and the spectroscopic signals from Li and D atom emission have been used. The experiments analyzed so far and simulated by ANSYS code, point out that heat loads as high as 2 MW/m2 for 1.5 s have been withstood without problems.

  5. Coronal Structures in Cool Stars: XMM-NEWTON Hybrid Stars and Coronal Evolution

    NASA Technical Reports Server (NTRS)

    Dupree, Andrea K.; Mushotzky, Richard (Technical Monitor)

    2003-01-01

    This program addresses the evolution of stellar coronas by comparing a solar-like corona in the supergiant Beta Dra (G2 Ib-IIa) to the corona in the allegedly more evolved state of a hybrid star, alpha TrA (K2 II-III). Because the hybrid star has a massive wind, it appears likely that the corona will be cooler and less dense as the magnetic loop structures are no longer closed. By analogy with solar coronal holes, when the topology of the magnetic field is configured with open magnetic structures, both the coronal temperature and density are lower than in atmospheres dominated by closed loops. The hybrid stars assume a pivotal role in the definition of coronal evolution, atmospheric heating processes and mechanisms to drive winds of cool stars. We are attempting to determine if this model of coronal evolution is correct by using XMM-NEWTON RGS spectra for the 2 targets we were allocated through the Guest Observer program.

  6. X-ray observations of complex temperature structure in the cool-core cluster A85

    SciTech Connect

    Schenck, David E.; Datta, Abhirup; Burns, Jack O.; Skillman, Sam

    2014-07-01

    X-ray observations were used to examine the complex temperature structure of A85, a cool-core galaxy cluster. Temperature features can provide evidence of merging events which shock heat the intracluster gas. Temperature maps were made from both Chandra and XMM-Newton observations. The combination of a new, long-exposure XMM observation and an improved temperature map binning technique produced the highest fidelity temperature maps of A85 to date. Hot regions were detected near the subclusters to the south and southwest in both the Chandra and XMM temperature maps. The presence of these structures implies A85 is not relaxed. The hot regions may indicate the presence of shocks. The Mach numbers were estimated to be ∼1.9 at the locations of the hot spots. Observational effects will tend to systematically reduce temperature jumps, so the measured Mach numbers are likely underestimated. Neither temperature map showed evidence for a shock in the vicinity of the presumed radio relic near the southwest subcluster. However, the presence of a weak shock cannot be ruled out. There was tension between the temperatures measured by the two instruments.

  7. Active cooling of pulse compression diffraction gratings for high energy, high average power ultrafast lasers.

    PubMed

    Alessi, David A; Rosso, Paul A; Nguyen, Hoang T; Aasen, Michael D; Britten, Jerald A; Haefner, Constantin

    2016-12-26

    Laser energy absorption and subsequent heat removal from diffraction gratings in chirped pulse compressors poses a significant challenge in high repetition rate, high peak power laser development. In order to understand the average power limitations, we have modeled the time-resolved thermo-mechanical properties of current and advanced diffraction gratings. We have also developed and demonstrated a technique of actively cooling Petawatt scale, gold compressor gratings to operate at 600W of average power - a 15x increase over the highest average power petawatt laser currently in operation. Combining this technique with low absorption multilayer dielectric gratings developed in our group would enable pulse compressors for petawatt peak power lasers operating at average powers well above 40kW.

  8. Fluxless Brazing and Heat Treatment of a Plate-Fin Sandwich Actively Cooled Panel

    NASA Technical Reports Server (NTRS)

    Beuyukian, C. S.

    1978-01-01

    The processes and techniques used to fabricate plate-fin sandwich actively cooled panels are presented. The materials were 6061 aluminum alloy and brazing sheet having clad brazing alloy. The panels consisted of small scale specimens, fatigue specimens, and a large 0.61 m by 1.22 m test panel. All panels were fluxless brazed in retorts in heated platen presses while exerting external pressure to assure intimate contact of details. Distortion and damage normally associated with that heat treatment were minimized by heat treating without fixtures and solution quenching in an organic polymer solution. The test panel is the largest fluxless brazed and heat treated panel of its configuration known to exist.

  9. A totally active scintillator calorimeter for the Muon Ionization Cooling Experiment (MICE). Design and construction

    NASA Astrophysics Data System (ADS)

    Asfandiyarov, Ruslan

    2013-12-01

    The Electron-Muon Ranger (EMR) is a totally active scintillator detector to be installed in the muon beam of the Muon Ionization Cooling Experiment (MICE) [1] - the main R&D project for the future neutrino factory. It is aimed at measuring the properties of the low energy beam composed of muons, electrons and pions, performing the identification particle by particle. The EMR is made of 48 stacked layers alternately measuring the X- and the Y-coordinate. Each layer consists of 59 triangular scintillator bars. It is shown that the granularity of the detector permits to identify tracks and to measure particle ranges and shower shapes. The read-out is based on FPGA custom made electronics and commercially available modules. Currently it is being built at the University of Geneva.

  10. Removing Cool Cores and Central Metallicity Peaks in Galaxy Clusters with Powerful Active Galactic Nucleus Outbursts

    NASA Astrophysics Data System (ADS)

    Guo, Fulai; Mathews, William G.

    2010-07-01

    Recent X-ray observations of galaxy clusters suggest that cluster populations are bimodally distributed according to central gas entropy and are separated into two distinct classes: cool core (CC) and non-cool core (NCC) clusters. While it is widely accepted that active galactic nucleus (AGN) feedback plays a key role in offsetting radiative losses and maintaining many clusters in the CC state, the origin of NCC clusters is much less clear. At the same time, a handful of extremely powerful AGN outbursts have recently been detected in clusters, with a total energy ~1061-1062 erg. Using two-dimensional hydrodynamic simulations, we show that if a large fraction of this energy is deposited near the centers of CC clusters, which is likely common due to dense cores, these AGN outbursts can completely remove CCs, transforming them to NCC clusters. Our model also has interesting implications for cluster abundance profiles, which usually show a central peak in CC systems. Our calculations indicate that during the CC to NCC transformation, AGN outbursts efficiently mix metals in cluster central regions and may even remove central abundance peaks if they are not broad enough. For CC clusters with broad central abundance peaks, AGN outbursts decrease peak abundances, but cannot effectively destroy the peaks. Our model may simultaneously explain the contradictory (possibly bimodal) results of abundance profiles in NCC clusters, some of which are nearly flat, while others have strong central peaks similar to those in CC clusters. A statistical analysis of the sizes of central abundance peaks and their redshift evolution may shed interesting insights on the origin of both types of NCC clusters and the evolution history of thermodynamics and AGN activity in clusters.

  11. Firefighter feedback during active cooling: a useful tool for heat stress management?

    PubMed

    Savage, Robbie J; Lord, Cara; Larsen, Brianna L; Knight, Teagan L; Langridge, Peter D; Aisbett, Brad

    2014-12-01

    Monitoring an individual's thermic state in the workplace requires reliable feedback of their core temperature. However, core temperature measurement technology is expensive, invasive and often impractical in operational environments, warranting investigation of surrogate measures which could be used to predict core temperature. This study examines an alternative measure of an individual's thermic state, thermal sensation, which presents a more manageable and practical solution for Australian firefighters operating on the fireground. Across three environmental conditions (cold, warm, hot & humid), 49 Australian volunteer firefighters performed a 20-min fire suppression activity, immediately followed by 20 min of active cooling using hand and forearm immersion techniques. Core temperature (Tc) and thermal sensation (TS) were measured across the rehabilitation period at five minute intervals. Despite the decline in Tc and TS throughout the rehabilitation period, there was little similarity in the magnitude or rate of decline between each measure in any of the ambient conditions. Moderate to strong correlations existed between Tc and TS in the cool (0.41, p<0.05) and hot & humid (0.57, p<0.05) conditions, however this was resultant in strong correlation during the earlier stages of rehabilitation (first five minutes), which were not evident in the latter stages. Linear regression revealed TS to be a poor predictor of Tc in all conditions (SEE=0.45-0.54°C) with a strong trend for TS to over-predict Tc (77-80% of the time). There is minimal evidence to suggest that ratings of thermal sensation, which represent a psychophysical assessment of an individual's thermal comfort, are an accurate reflection of the response of an individual's core temperature. Ratings of thermal sensation can be highly variable amongst individuals, likely moderated by local skin temperature. In account of these findings, fire managers require a more reliable source of information to guide

  12. Cooling Water Intakes

    EPA Pesticide Factsheets

    Industries use large volumes of water for cooling. The water intakes pull large numbers of fish and other organisms into the cooling systems. EPA issues regulations on intake structures in order to minimize adverse environmental impacts.

  13. Methodology to determine cost and performance goals for active solar cooling systems

    NASA Astrophysics Data System (ADS)

    Warren, M. L.; Wahlig, M.

    1981-11-01

    Systems analysis is used to calculate the 20 yr. present value of energy savings of solar cooling systems located in Texas, Arizona, Florida, and Washington, DC, and methods of solar system development to meet the cost goals of economic operation are outlined. Solar cooling systems are projected to begin commercial entry in 1986 and reach 20% of the total cooling market by the year 2000, producing 0.14 quads of displaced energy. A numerical simulation was carried out for both residential and commercial solar cooling units with consideration for system cost goals, cost goals per unit collector area, and the cost goals per ton of cooling. System size was targeted as a 3 ton residential chiller and a 25 ton commercial absorption cooling unit. The costs for volume production are provided, along with trends for an incrementally decreasing need for tax incentives, ending in about 1994

  14. Study of heat exchange in cooling systems of heat-stressed structures

    NASA Astrophysics Data System (ADS)

    Vikulin, A. V.; Yaroslavtsev, N. L.; Zemlyanaya, V. A.

    2017-01-01

    Increasing working parameters of the cycle of gas-turbine engines, complicating design of gas-turbine plants, as well as growing aerodynamic, thermal, static, and dynamic loads, necessitate the development of promising cooling systems for heat-stressed structures. This work is devoted to an experimental study of heat exchange in ducts equipped with systems of inclined and cross walls (fins). It has been found that an increase in the Reynolds number Re from 3000 to 20000 leads to a decrease in the heat exchange, which is characterized by the relative Nusselt number overline{Nu}, by 19-30% at the angle of inclination of the walls φ = 0, 40°, 50°, and 90° if the length of the walls x w is comparable to the spacing b s and by 12-15% at φ = 30° and 90° if x w ≫ b s. If cross walls are used in cooling ducts, the length of the walls x w plays the governing role; an increase in this characteristic from 1.22 × 10-3 to 3.14 × 10-3 m leads to an increase in the intensity of heat exchange by 30-40% and to a decrease in the capacity of the entire system of the walls. It has been shown that, on surfaces with wavy fins, the intensity of heat exchange is closest to that determined in the models under study. For example, values of the Colborne criterion StPr2/3 for ducts equipped with wavy fins and for the models under study differ only slightly (by 2-20% depending on the value of the angle φ). However, the difference for surfaces with short plate fins and ducts equipped with inclined walls is high (30-40%). This is due to the design features of these surfaces and to the severe effect of the inlet portion on heat exchange, since the surfaces are characterized by a higher ratio of the duct length to the hydraulic diameter L/d h at small fin thicknesses ((0.1-0.15) × 10-3 m). The experimental results can be used in developing designs of nozzle and rotor blades of high-temperature gas turbines in gas-turbine engines and plants.

  15. Experimental characterization of the ITER TF structure cooling in HELIOS test facility

    NASA Astrophysics Data System (ADS)

    Hoa, C.; Rousset, B.; Lacroix, B.; Nicollet, S.; Vallcorba, R.; Bessette, D.; Vostner, A.; Gauthier, F.

    2015-12-01

    During ITER plasma operation, large thermal loads are generated in the stainless steel Toroidal Field (TF) coil casing. To minimize the impact on the temperature of the TF Cable in Conduit Conductor (CICC), these heat loads are intercepted by case cooling channels which are implemented at the interface to the winding pack. One of the design options for the case cooling channels consists of a stainless steel pipe inserted in a rectangular groove which is machined in the casing and filled by a charged resin of high thermal conductivity. A higher number of cooling pipes is arranged at the plasma facing wall of the case, thus providing a better shielding to the TF conductor at high field. To assess the efficiency of the cooling pipes and their thermal coupling with the charged resin, experimental characterizations have been performed. First of all, the thermal resistance vs temperature of some of the individual components of a TF coil has been measured on representative samples in a cryogenic bench. Further characterizations have been performed on an integrated mock-up of the TF cooling scheme at cryogenic temperature in HELIOS test facility at CEA Grenoble. The mock-up consists of a piece of TF casing that can be heated uniformly on its surface, one cooling channel implemented in the groove which is filled with the charged resin, the filler, the ground insulation, the radial plate and one insulated CICC. The cooling pipe and the CICC are cooled by supercritical helium at 4.4 K and 5 bar; the instrumentation consists of temperature, pressure and mass flow sensors. Both stationary and transient operating modes have been investigated to assess the thermal efficiency of the case cooling design. The experimental tests are presented and the first results are discussed and analyzed in this document.

  16. Structure activity relationships of spiramycins.

    PubMed

    Omura, S; Sano, H; Sunazuka, T

    1985-07-01

    Sixty-six derivatives of spiramycin I and neospiramycin I were synthesized and evaluated by four parameters, MIC, affinity to ribosomes (ID50), therapeutic effect in mice and retention time in HPLC. Among the derivatives, 3,3'',4''-tri-O-propionyl- and 3,4''-di-O-acetyl-3''-O-butyrylspiramycin I showed the highest therapeutic effect which was superior to acetylspiramycin. Structure activity relationships of spiramycins are discussed.

  17. Thermal Manikin Evaluation of Passive and Active Cooling Garments to Improve Comfort of Military Body Armor

    DTIC Science & Technology

    2007-08-01

    increased TM evaporative cooling potential approximately 18%. Military use of these garments could allow for increases in sweat evaporation and overall thermal comfort during operational heat exposure.

  18. Cooling rate and thermal structure determined from progressive magnetization of the dacite dome at Mount St. Helens, Washington

    USGS Publications Warehouse

    Dzurisin, D.; Denlinger, R.P.; Rosenbaum, J.G.

    1990-01-01

    Our study of a magnetic anomaly associated with the recently active dacite dome at Mount St. Helens suggests that the dome consists of a hot, nonmagnetized core surrounded by a cool, magnetized carapace and flanking talus. Temporal changes in the magnetic anomaly indicate that the magnetized carapace thickened at an average rate of 0.03 ?? 0.01 m/d from 1984 to 1986. Petrographic and rock magnetic properties of dome samples indicate that the dominant process responsible for these changes is magnetization of extensively oxidized rock at progressively deeper levels within the dome as the rock cools through its blocking temperature, rather than subsequent changes in magnetization caused by further oxidation. Newly extruded material cools rapidly for a short period as heat is conducted outward in response to convective heat loss from its surface. The cooling rate gradually declines for several weeks, and thereafter the material cools at a relatively constant rate by convective heat loss from its interior along fractures that propagate inward. -from Authors

  19. Cooling Vest

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Because quadriplegics are unable to perspire below the level of spinal injury, they cannot tolerate heat stress. A cooling vest developed by Ames Research Center and Upjohn Company allows them to participate in outdoor activities. The vest is an adaptation of Ames technology for thermal control garments used to remove excess body heat of astronauts. The vest consists of a series of corrugated channels through which cooled water circulates. Its two outer layers are urethane coated nylon, and there is an inner layer which incorporates the corrugated channels. It can be worn as a backpack or affixed to a wheelchair. The unit includes a rechargeable battery, mini-pump, two quart reservoir and heat sink to cool the water.

  20. FLPP NGL Structural Subsystems Activity

    NASA Astrophysics Data System (ADS)

    Jaredson, D.; Ramusat, G.; Appel, S.; Cardone, T.; Persson, J.; Baiocco, P.; Lavelle, F.; Bouilly, Th.

    2012-07-01

    The ESA Future Launchers Preparatory Programme (FLPP) is the basis for new paradigms, investigating the key elements, logic and roadmaps to prepare the development of the safe, reliable and low cost next European Launch Vehicle (LV) for access to space (dubbed NGL - Next Generation LV), with an initial operational capability mid-next decade. In addition to carry cargo to conventional GTO or SSO, the European NGL has to be flexible enough to cope with new pioneering institutional missions as well as the evolving commercial payloads market. This achievement is broached studying three main areas relevant to ELVs: System concepts, Propulsion and Core Technology During the preliminary design activity, a number of design alternatives concerning NGL main structural subsystems have been investigated. Technology is one of the ways to meet the NGL challenges to either improve the performances or to reduce the cost or both. The relevant requirements allow to steer a ‘top-down’ approach for their conception and to propose the most effective technologies. Furthermore, all these technology developments represent a significant ‘bottom-up’ approach investment and concern a large range of activities. The structural subsystems portfolio of the FLPP ‘Core Technology’ activity encompasses major cutting-edge challenges for maturation of the various subsystems leading to reduce overall structural mass, increasing structural margins for robustness, metallic and composite containment of cryogenic propellants, significantly reducing fabrication and operations cost, etc. to derive performing upper and booster stages. Application of concurrent engineering methods will allow developments of performing technology demonstrators in terms of need, demonstration objective, size and cost yielding to safe, low-risk technical approaches for a future development. Potential ability of these advanced structural LV technologies to satisfy the system requirements of the NGL and their current

  1. Tractor Mechanics. Maintaining and Servicing the Cooling System, Learning Activity Packages 34-40; Maintaining and Servicing Hydraulic Systems, Learning Activity Packages 41-48.

    ERIC Educational Resources Information Center

    Clemson Univ., SC. Vocational Education Media Center.

    This series of learning activity packages focuses on two areas of tractor mechanics: (1) maintaining and servicing the cooling system and (2) maintaining and servicing hydraulic systems. Each of the fifteen illustrated learning activity packages follows a typical format: introduction, directions, objectives, learning activities, tools and…

  2. Design of multi-megawatt actively cooled beam dumps for the Neutral-Beam Engineering Test Facility

    SciTech Connect

    Paterson, J.A.; Koehler, G.; Wells, R.P.

    1981-10-01

    The Neutral Beam Engineering Test Facility will test Neutral Beam Sources up to 170 keV, 65 Amps, with 30 second beam-on times. For this application actively cooled beam dumps for both the neutral and ionized particles will be required. The dumps will be able to dissipate a wide range of power density profiles by utilizing a standard modular panel design which is incorporated into a moveable support structure. The thermal hydraulic design of the panels permit the dissipation of 2 kW/cm/sup 2/ anywhere on the panel surface. The water requirements of the dumps are optimized by restricting the flow to panel sections where the heat flux falls short of the design value. The mechanical design of the beam-dump structures is described along with tests performed on a prototype panel. The prototype tests were performed on two different panel designs, one manufactured by Mc Donnell Douglas (MDAC) the other by United Technologies (UT). The dissipation capabilities of the panels were tested at the critical regions to verify their use in the beam dump assemblies.

  3. Desensitization of menthol-activated cold receptors in lower extremities during local cooling in young women with a cold constitution.

    PubMed

    Yamazaki, Fumio; Sone, Ryoko

    2017-03-01

    To test the hypothesis that topical menthol-induced reactivity of cold sensation and cutaneous vasoconstriction to local cooling is augmented in individuals with a cold constitution, we examined thermal sensation and cutaneous vasoconstrictor responses at menthol-treated and untreated sites in the legs during local skin cooling in young women complaining of chilliness (C group) and young women with no complaint as a normal control group (N group). During local skin cooling, the sensitivity to cold sensation was greater in the C group than in the N group. The application of menthol enhanced the cold sensation at a low temperature in the N group, but not in the C group. Cutaneous vasoconstrictor responses to local skin cooling were not altered by menthol treatment in either of the two groups. These findings suggest the desensitization of menthol-activated cold receptors in the legs of C group subjects, and a minor role of cold receptor activity in cutaneous vasoconstrictor response to local cooling.

  4. Electronic spectroscopy of jet-cooled HCP+: molecular structure, phosphorus hyperfine structure, and Renner-Teller analysis.

    PubMed

    Sunahori, Fumie X; Zhang, Xiaopeng; Clouthier, Dennis J

    2007-09-14

    Laser-induced fluorescence spectra of jet-cooled HCP(+) and DCP(+) have been obtained with the pulsed discharge technique using HCPDCP and argon precursor mixtures. Transitions involving all of the excited state vibrations have been observed and a set of vibrational constants has been obtained. High-resolution spectra of the (2)Pi(32) components of the 0(0) (0) bands of both isotopomers have been recorded, and these spectra show resolved phosphorus hyperfine structure which allowed the determination of the excited state Fermi contact parameter. The B values were used to obtain the ground and excited state effective geometric parameters as r(0) (")(CH)=1.077(2) A, r(0) (")(CP)=1.6013(3) A, r(0) (')(CH)=1.082(2) A, and r(0) (')(CP)=1.5331(3) A. A Renner-Teller analysis of the ground state vibrational energy levels obtained from the literature was attempted. All of the observed levels of DCP(+) and the majority of those of HCP(+) were satisfactorily fitted with a standard Renner-Teller model, but three HCP(+) levels showed large systematic deviations which could not be accommodated by reassignments or improvements in the Fermi resonance Hamiltonian. Further improvements in the theory or in the experimental data will be needed to resolve this discrepancy.

  5. Integrin activation and structural rearrangement.

    PubMed

    Takagi, Junichi; Springer, Timothy A

    2002-08-01

    Among adhesion receptor families, integrins are particularly important in biological processes that require rapid modulation of adhesion and de-adhesion. Activation on a timescale of < 1 s of beta2 integrins on leukocytes and beta3 integrins on platelets enables deposition of these cells at sites of inflammation or vessel wall injury. Recent crystal, nuclear magnetic resonance (NMR), and electron microscope (EM) structures of integrins and their domains lead to a unifying mechanism of activation for both integrins that contain and those that lack an inserted (I) domain. The I domain adopts two alternative conformations, termed open and closed. In striking similarity to signaling G-proteins, rearrangement of a Mg2+-binding site is linked to large conformational movements in distant backbone regions. Mutations that stabilize a particular conformation show that the open conformation has high affinity for ligand, whereas the closed conformation has low affinity. Movement of the C-terminal alpha-helix 10 A down the side of the domain in the open conformation is sufficient to increase affinity at the distal ligand-binding site 9,000-fold. This C-terminal "bell-rope" provides a mechanism for linkage to conformational movements in other domains. Recent structures and functional studies reveal interactions between beta-propeller, I, and I-like domains in the integrin headpiece, and a critical role for integrin epidermal growth factor (EGF) domains in the stalk region. The headpiece of the integrin faces down towards the membrane in the inactive conformation, and extends upward in a "switchblade"-like opening upon activation. These long-range structural rearrangements of the entire integrin molecule involving interdomain contacts appear closely linked to conformational changes within the I and I-like domains, which result in increased affinity and competence for ligand binding.

  6. A relationship between halo mass, cooling, active galactic nuclei heating and the co-evolution of massive black holes

    NASA Astrophysics Data System (ADS)

    Main, R. A.; McNamara, B. R.; Nulsen, P. E. J.; Russell, H. R.; Vantyghem, A. N.

    2017-02-01

    We derive X-ray mass, luminosity, and temperature profiles for 45 galaxy clusters to explore relationships between halo mass, active galactic nuclei (AGN) feedback, and central cooling time. We find that radio-mechanical feedback power (referred to here as `AGN power') in central cluster galaxies correlates with halo mass as Pmech ∝ M1.55 ± 0.26, but only in haloes with central atmospheric cooling times shorter than 1 Gyr. The trend of AGN power with halo mass is consistent with the scaling expected from a self-regulating AGN feedback loop, as well as with galaxy and central black hole co-evolution along the MBH-σ relation. AGN power in clusters with central atmospheric cooling times longer than ˜1 Gyr typically lies two orders of magnitude below those with shorter central cooling times. Galaxies centred in clusters with long central cooling times nevertheless experience ongoing and occasionally powerful AGN outbursts. We further investigate the impact of feedback on cluster scaling relations. We find L-T and M-T relations in clusters with direct evidence of feedback which are steeper than self-similar, but not atypical compared to previous studies of the full cluster population. While the gas mass rises, the stellar mass remains nearly constant with rising total mass, consistent with earlier studies. This trend is found regardless of central cooling time, implying tight regulation of star formation in central galaxies as their haloes grew, and long-term balance between AGN heating and atmospheric cooling. Our scaling relations are presented in forms that can be incorporated easily into galaxy evolution models.

  7. Heating and Cooling System Design for a Modern Transportable Container

    SciTech Connect

    Berger, Jason E.

    2015-06-01

    Sandia National Laboratories (SNL) has been tasked with the design of a modern transportable container (MTC) for use in high reliability transportation environments. The container is required to transport cargo capable of generating its own heat and operate under the United States’ climatic extremes. In response to these requirements, active heating and cooling is necessary to maintain a controlled environment inside the container. The following thesis project documents the design of an active heating, active cooling, and combined active heating and cooling system (now referred to as active heating and cooling systems) through computational thermal analyses, scoping of commercial system options, and mechanical integration with the container’s structure.

  8. The effect of cooling speed on the structure and properties of the heat affected zone in welded compounds of ferrite-austenitic steels

    NASA Astrophysics Data System (ADS)

    Gonik, I. L.; Gurulev, D. N.; Bondareva, O. P.

    2017-02-01

    Such parameters as the maximum heating temperature, duration of stay at high temperatures, the rate of cooling influence greatly the structure and properties of the heat-affected zone of welded joints of steels and alloys. In the present work, the effect of different cooling speed upon the impact of the thermal cycle of welding on the structure, the fine structure and toughness of ferrite-austenitic steels is investigated. It is established that the cooling speed after welding has a great influence on the shock impact toughness, the phase composition and the structure of the zone of ferrite-austenitic steels.

  9. Effect of Temperature, Fractional Deformation, and Cooling Rate on the Structure and Properties of Steel 09GNB

    NASA Astrophysics Data System (ADS)

    Kodzhaspirov, G. E.; Sulyagin, R. V.

    2005-01-01

    The effect of temperature, divisibility of deformation, and cooling rate in high-temperature thermomechanical treatment (HTTMT) on the structure and mechanical properties of low-alloy steel 09GNB is studied. The steel is used as a high-strength material for the production of offshore structures, strips, and other welded articles. The study is performed using the method of experimental design where the parameters are fractional deformation (number of passes in rolling), final temperature of the deformation, and rate of post-deformation cooling. The results of the experiments are used to construct regression equations describing the qualitative and quantitative effect of the parameters of HTTMT on the mechanical properties of the steel. Microstructure and fracture surfaces of the steel are analyzed.

  10. Suppressing cluster cooling flows by self-regulated heating from a spatially distributed population of active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Nusser, Adi; Silk, Joseph; Babul, Arif

    2006-12-01

    Existing models invoking active galactic nucleus (AGN) activity to resolve the cooling flow conundrum in galaxy clusters focus exclusively on the role of the central galaxy. Such models require fine-tuning of highly uncertain microscopic transport properties to distribute the thermal over the entire cluster cooling core. We propose that the intracluster medium (ICM) is instead heated by multiple, spatially distributed AGN. The central regions of galaxy clusters are rich in spheroidal systems, all of which are thought to host black holes and could participate in the heating of the ICM via AGN activity of varying strengths, and they do. There is mounting observational evidence for multiple AGN in cluster environments. AGN drive bubbles into the ICM. We identify three distinct interactions between the bubble and the ICM: (1) upon injection, the bubbles expand rapidly in situ to reach pressure equilibrium with their surroundings, generating shocks and waves whose dissipation is the principal source of ICM heating; (2) once inflated, the bubbles rise buoyantly at a rate determined by a balance with the viscous drag force, which itself results in some additional heating; and (3) rising bubbles expand and compress their surroundings. This process is adiabatic and does not contribute to any additional heating; rather, the increased ICM density due to compression enhances cooling. Our model sidesteps the `transport' issue by relying on the spatially distributed galaxies to heat the cluster core. We include self-regulation in our model by linking AGN activity in a galaxy to cooling characteristics of the surrounding ICM. We use a spherically symmetric one-dimensional hydrodynamical code to carry out a preliminary study illustrating the efficacy of the model. Our self-regulating scenario predicts that there should be enhanced AGN activity of galaxies inside the cooling regions compared to galaxies in the outer parts of the cluster. This prediction remains to be confirmed or

  11. Highly porous activated carbon based adsorption cooling system employing difluoromethane and a mixture of pentafluoroethane and difluoromethane

    NASA Astrophysics Data System (ADS)

    Askalany, Ahmed A.; Saha, Bidyut B.

    2017-01-01

    This paper presents a simulation for a low-grade thermally powered two-beds adsorption cooling system employing HFC-32 and a mixture of HFC-32 and HFC-125 (HFC-410a) with activated carbon of type Maxsorb III. The present simulation model adopts experimentally measured adsorption isotherms, adsorption kinetics and isosteric heat of adsorption data. Effect of operating conditions (mass flow rate of hot water, driving heat source temperature and evaporator temperature) on the system performance has been studied in detail. The simulation results showed that the system could be powered by low-grade heat source temperature (below 85 °C). AC/HFC-32 and AC/HFC-410a adsorption cooling cycles achieved close specific cooling power and coefficient of performance values of 0.15 kW/kg and 0.3, respectively at a regeneration temperature of 90 °C along with evaporator temperature of 10 °C. The investigated semi continuous adsorption cooling system could produce a cooling power of 9 kW.

  12. Cooling rate and size effects on the medium-range structure of multicomponent oxide glasses simulated by molecular dynamics

    NASA Astrophysics Data System (ADS)

    Tilocca, Antonio

    2013-09-01

    A set of molecular dynamics simulations were performed to investigate the effect of cooling rate and system size on the medium-range structure of melt-derived multicomponent silicate glasses, represented by the quaternary 45S5 Bioglass composition. Given the significant impact of the glass degradation on applications of these materials in biomedicine and nuclear waste disposal, bulk structural features which directly affect the glass dissolution process are of particular interest. Connectivity of the silicate matrix, ion clustering and nanosegregation, distribution of ring and chain structural patterns represent critical features in this context, which can be directly extracted from the models. A key issue is represented by the effect of the computational approach on the corresponding glass models, especially in light of recent indications questioning the suitability of conventional MD approaches (that is, involving melt-and-quench of systems containing ˜103 atoms at cooling rates of 5-10 K/ps) when applied to model these glasses. The analysis presented here compares MD models obtained with conventional and nonconventional cooling rates and system sizes, highlighting the trend and range of convergence of specific structural features in the medium range. The present results show that time-consuming computational approaches involving much lower cooling rates and/or significantly larger system sizes are in most cases not necessary in order to obtain a reliable description of the medium-range structure of multicomponent glasses. We identify the convergence range for specific properties and use them to discuss models of several glass compositions for which a possible influence of cooling-rate or size effects had been previously hypothesized. The trends highlighted here represent an important reference to obtain reliable models of multicomponent glasses and extract converged medium-range structural features which affect the glass degradation and thus their application

  13. Cooling rate and size effects on the medium-range structure of multicomponent oxide glasses simulated by molecular dynamics

    SciTech Connect

    Tilocca, Antonio

    2013-09-21

    A set of molecular dynamics simulations were performed to investigate the effect of cooling rate and system size on the medium-range structure of melt-derived multicomponent silicate glasses, represented by the quaternary 45S5 Bioglass composition. Given the significant impact of the glass degradation on applications of these materials in biomedicine and nuclear waste disposal, bulk structural features which directly affect the glass dissolution process are of particular interest. Connectivity of the silicate matrix, ion clustering and nanosegregation, distribution of ring and chain structural patterns represent critical features in this context, which can be directly extracted from the models. A key issue is represented by the effect of the computational approach on the corresponding glass models, especially in light of recent indications questioning the suitability of conventional MD approaches (that is, involving melt-and-quench of systems containing ∼10{sup 3} atoms at cooling rates of 5-10 K/ps) when applied to model these glasses. The analysis presented here compares MD models obtained with conventional and nonconventional cooling rates and system sizes, highlighting the trend and range of convergence of specific structural features in the medium range. The present results show that time-consuming computational approaches involving much lower cooling rates and/or significantly larger system sizes are in most cases not necessary in order to obtain a reliable description of the medium-range structure of multicomponent glasses. We identify the convergence range for specific properties and use them to discuss models of several glass compositions for which a possible influence of cooling-rate or size effects had been previously hypothesized. The trends highlighted here represent an important reference to obtain reliable models of multicomponent glasses and extract converged medium-range structural features which affect the glass degradation and thus their

  14. Strigolactones: structures and biological activities.

    PubMed

    Yoneyama, Koichi; Xie, Xiaonan; Yoneyama, Kaori; Takeuchi, Yasutomo

    2009-05-01

    Strigolactones released from plant roots induce seed germination of root parasitic weeds, witchweeds (Striga spp.) and broomrapes (Orobanche spp.), and hyphal branching of symbiotic arbuscular mycorrhizal (AM) fungi. In addition to these functions in the rhizosphere, strigolactones have recently been shown to be a novel class of plant hormones regulating shoot outgrowth. The natural strigolactones identified so far have the common C-D ring moiety, which is thought to be the essential structure for exhibiting biological activity. The introduction of substitutions on the A-B ring moiety of 5-deoxystrigol, the basic strigolactone, affords various strigolactones, e.g. hydroxylation on C-4, C-5 and C-9 leads to orobanchol, strigol and sorgomol respectively. Then, acetylation and probably other derivatisations of these hydroxy-strigolactones would occur. Although the C-2'-(R) stereochemistry was thought to be an important structural feature for potent germination stimulation activity, 2'-epi-strigolactones were found in root exudates of tobacco, rice, pea and other plant species, indicating that at least some plants produce both epimers.

  15. Particle exhaust of helium plasmas with actively cooled outboard pump limiter on Tore Supra

    SciTech Connect

    Uckan, T.; Mioduszewski, P.K.; Loarer, T.; Chatelier, M.; Guilhem, D.; Lutz, T.; Nygren, R.E.; Mahdavi, M.A.

    1995-08-01

    The superconducting tokamak Tore Supra was designed for long-pulse (30-s) high input power operation. Here observations on the particle-handling characteristics of the actively cooled modular outboard pump limiter (OPL) are presented for helium discharges. The important experimental result was that a modest pumping speed (1 m{sup 3}/s) of the OPL turbomolecular pump (TMP) provided background helium exhaust. This result came about due to a well-conditioned vessel wall with helium discharges that caused no wall outgasing. The particle accountability in these helium discharges was excellent, and the well-conditioned wall did not play a significant role in the particle balance. The helium density control, 25% density drop with OPL exhaust efficiency of {approximately}1%, was possible with TMP although this may not be the case with reactive gases such as deuterium. The observed quadratic increase of the OPL neutral pressure with helium density was consistent with an improvement of the particle control with increasing plasma density.

  16. Simulation of cooling and solidification of three-dimensional bulk borosilicate glass: effect of structural relaxations

    NASA Astrophysics Data System (ADS)

    Barth, N.; George, D.; Ahzi, S.; Rémond, Y.; Joulaee, N.; Khaleel, M. A.; Bouyer, F.

    2014-02-01

    The modeling of the viscoelastic stress evolution and specific volume relaxation of a bulky glass cast is presented in this article and is applied to the experimental cooling process of an inactive nuclear waste vitrification process. The concerned borosilicate glass is solidified and cooled down to ambient temperature in a stainless steel canister, and the thermomechanical response of the package is simulated. There exists a deviant compression of the liquid core due to the large glass package compared to standard tempered glass plates. The stress load development of the glass cast is finally studied for different thermal load scenarios, where the cooling process parameters or the final cooldown rates were changed, and we found a great influence of the studied cooldown rates on the maximum stress build-up at ambient temperature.

  17. Simulation of cooling and solidification of three-dimensional bulk borosilicate glass. Effect of structural relaxations

    SciTech Connect

    Barth, N.; George, D.; Ahzi, Said; Remond, Y.; Joulaee, N.; Khaleel, Mohammad A.; Bouyer, F.

    2013-04-20

    The modeling of the viscoelastic stress evolution and specific volume relaxation of a bulky glass cast is presented in this article and is applied to the experimental cooling process of an inactive nuclear waste vitrification process. The concerned borosilicate glass is solidified and cooled down to ambient temperature in a stainless steel canister, and the thermomechanical response of the package is simulated. There exists a deviant compression of the liquid core due to the large glass package compared to standard tempered glass plates. The stress load development of the glass cast is finally studied for different thermal load scenarios, where the cooling process parameters or the final cooldown rates were changed, and we found a great influence of the studied cooldown rates on the maximum stress buildup at ambient temperature.

  18. Simulation of cooling and solidification of three-dimensional bulk borosilicate glass: effect of structural relaxations

    NASA Astrophysics Data System (ADS)

    Barth, N.; George, D.; Ahzi, S.; Rémond, Y.; Joulaee, N.; Khaleel, M. A.; Bouyer, F.

    2013-04-01

    The modeling of the viscoelastic stress evolution and specific volume relaxation of a bulky glass cast is presented in this article and is applied to the experimental cooling process of an inactive nuclear waste vitrification process. The concerned borosilicate glass is solidified and cooled down to ambient temperature in a stainless steel canister, and the thermomechanical response of the package is simulated. There exists a deviant compression of the liquid core due to the large glass package compared to standard tempered glass plates. The stress load development of the glass cast is finally studied for different thermal load scenarios, where the cooling process parameters or the final cooldown rates were changed, and we found a great influence of the studied cooldown rates on the maximum stress build-up at ambient temperature.

  19. First wall structural analysis of the aqueous self-cooled blanket concept

    SciTech Connect

    O'Brien, D.A.; Steiner, D.; Embrechts, M.J.; Deutch, L.; Gierszewski, P.

    1986-11-01

    A recently proposed blanket concept using water coolant with dissolved lithium compounds for breeding employs water cooled first walls. Water cooled first walls for blankets have also been proposed for some solid breeder blankets. Design options for water cooled first walls are examined in this paper. Four geometries and three materials are analyzed for water coolant at 300/sup 0/C and 13.8 MPa (2000 psi). Maximum neutron wall loads (with surface heat loads being 25% of neutron wall load) are determined for each geometry and material combination. Of the materials studied, only vanadium alloy is found to be capable of withstanding high wall loads (>10MW/m/sup 2/ neutron and >2.5 MW/m/sup 2/ heat).

  20. Aero-Thermo-Structural Design Optimization of Internally Cooled Turbine Blades

    NASA Technical Reports Server (NTRS)

    Dulikravich, G. S.; Martin, T. J.; Dennis, B. H.; Lee, E.; Han, Z.-X.

    1999-01-01

    A set of robust and computationally affordable inverse shape design and automatic constrained optimization tools have been developed for the improved performance of internally cooled gas turbine blades. The design methods are applicable to the aerodynamics, heat transfer, and thermoelasticity aspects of the turbine blade. Maximum use of the existing proven disciplinary analysis codes is possible with this design approach. Preliminary computational results demonstrate possibilities to design blades with minimized total pressure loss and maximized aerodynamic loading. At the same time, these blades are capable of sustaining significantly higher inlet hot gas temperatures while requiring remarkably lower coolant mass flow rates. These results suggest that it is possible to design internally cooled turbine blades that will cost less to manufacture, will have longer life span, and will perform as good, if not better than, film cooled turbine blades.

  1. Heat transfer model to characterize the focal cooling necessary to suppress spontaneous epileptiform activity (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Guerra, Reynaldo G.; Davalos, Rafael V.; Garcia, Paul A.; Rubinsky, Boris; Berger, Mitchel

    2005-04-01

    Epilepsy is characterized by paroxysmal transient disturbances of the electrical activity of the brain. Symptoms are manifested as impairment of motor, sensory, or psychic function with or without loss of consciousness or convulsive seizures. This paper presents an initial post-operative heat transfer analysis of surgery performed on a 41 year-old man with medically intractable Epilepsy. The surgery involved tumor removal and the resection of adjacent epileptogenic tissue. Electrocorticography was performed before resection. Cold saline was applied to the resulting interictal spike foci resulting in transient, complete cessation of spiking. A transient one dimensional semi-infinite finite element model of the surface of the brain was developed to simulate the surgery. An approximate temperature distribution of the perfused brain was developed by applying the bioheat equation. The model quantifies the surface heat flux reached in achieving seizure cessation to within an order of magnitude. Rat models have previously shown that the brain surface temperature range to rapidly terminate epileptogenic activity is 20-24°C. The developed model predicts that a constant heat flux of approximately -13,000W/m2, applied at the surface of the human brain, would achieve a surface temperature in this range in approximately 3 seconds. A parametric study was subsequently performed to characterize the effects of brain metabolism and brain blood perfusion as a function of the determined heat flux. The results of these findings can be used as a first approximation in defining the specifications of a cooling device to suppress seizures in human models.

  2. Development of wind operated passive evaporative cooling structures for storage of tomatoes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A wind operated passive evaporative cooler was developed. Two cooling chambers were made with clay containers (cylindrical and square shapes). These two containers were separately inserted inside bigger clay pot inter- spaced with clay soil of 7 cm (to form pot-in-pot and wall-in wall) with the outs...

  3. COOLED NEUTRONIC REACTOR

    DOEpatents

    Binner, C.R.; Wilkie, C.B.

    1958-03-18

    This patent relates to a design for a reactor of the type in which a fluid coolant is flowed through the active portion of the reactor. This design provides for the cooling of the shielding material as well as the reactor core by the same fluid coolant. The core structure is a solid moderator having coolant channels in which are disposed the fuel elements in rod or slug form. The coolant fluid enters the chamber in the shield, in which the core is located, passes over the inner surface of said chamber, enters the core structure at the center, passes through the coolant channels over the fuel elements and out through exhaust ducts.

  4. EFFECT OF ACTIVE COOLING AND α-2 ADRENOCEPTOR ANTAGONISM ON CORE TEMPERATURE IN ANESTHETIZED BROWN BEARS (URSUS ARCTOS).

    PubMed

    Ozeki, Larissa Mourad; Caulkett, Nigel; Stenhouse, Gordon; Arnemo, Jon M; Fahlman, Åsa

    2015-06-01

    Hyperthermia is a common complication during anesthesia of bears, and it can be life threatening. The objective of this study was to evaluate the effectiveness of active cooling on core body temperature for treatment of hyperthermia in anesthetized brown bears (Ursus arctos). In addition, body temperature after reversal with atipamezole was also evaluated. Twenty-five adult and subadult brown bears were captured with a combination of zolazepam-tiletamine and xylazine or medetomidine. A core temperature capsule was inserted into the bears' stomach or 15 cm into their rectum or a combination of both. In six bears with gastric temperatures≥40.0°C, an active cooling protocol was performed, and the temperature change over 30 min was analyzed. The cooling protocol consisted of enemas with 2 L of water at approximately 5°C/100 kg of body weight every 10 min, 1 L of intravenous fluids at ambient temperature, water or snow on the paws or the inguinal area, intranasal oxygen supplementation, and removing the bear from direct sunlight or providing shade. Nine bears with body temperature>39.0°C that were not cooled served as control for the treated animals. Their body temperatures were recorded for 30 min, prior to administration of reversal. At the end of the anesthetic procedure, all bears received an intramuscular dose of atipamezole. In 10 bears, deep rectal temperature change over 30 min after administration of atipamezole was evaluated. The active cooling protocol used in hyperthermic bears significantly decreased their body temperatures within 10 min, and it produced a significantly greater decrease in their temperature than that recorded in the control group.

  5. The effect of composition and cooling rate on the structure of rapidly solidified (Fe, Ni)3Al-C alloy

    NASA Technical Reports Server (NTRS)

    Myers, S. A.; Koch, C. C.

    1989-01-01

    The quench rate-metastable structure dependence in the Fe-20Ni-8Al-2C wt pct alloy has been experimentally studied. The nonequilibrium gamma-prime and gamma phases were noted in foils 65-100 microns thick, while at higher quench rates (thinner samples) the matrix was found to be in a disordered fcc gamma phase with kappa carbide precipitates. With the addition of silicon to the alloys, the nonequilibrium gamma-prime and gamma structures are observed at higher cooling rates.

  6. Structure Refinement by a Liquid Metal Cooling Solidification Process for Single-Crystal Nickel-Base Superalloys

    NASA Astrophysics Data System (ADS)

    Brundidge, C. L.; van Drasek, D.; Wang, B.; Pollock, T. M.

    2012-03-01

    Single crystals of a nickel-base superalloy were directionally solidified (DS) over a range of cooling rates to evaluate the benefits of a new high thermal gradient solidification process. Solidification experiments were conducted on cylindrical bars with a liquid-metal-enhanced cooling process. This higher gradient casting process was evaluated for the degree of structure refinement, microstructural variability, and porosity distributions. Cylindrical bars of 1.6-cm diameter were solidified at rates between 8.4 and 21.2 mm/min using a tin-based, liquid metal cooling (LMC) technique and at a rate of 3.4 mm/min with a conventional Bridgman process. The LMC process produced a refined microstructure with average primary dendrite arm spacing (PDAS) and secondary dendrite arm spacing (SDAS) values as low as 164 and 25 μm, respectively, for the bar geometry evaluated. An optimum intermediate withdrawal velocity of 12.7 mm/min produced up to a 50 and 60 pct refinement in PDAS and SDAS, respectively. Further increases in withdrawal velocity produced smaller SDAS and pore sizes, but undesirable grain boundaries and excessive secondary dendrite arm growth. Voronoi tessellation methods were used to examine the extremes of the dendrite arm spacings in comparison to the average measurements, the packing of dendrites, and the correlation of porosity size and location with the dendrite structure. A simple expression for prediction of the maximum pore size is developed.

  7. Structural insights on complement activation.

    PubMed

    Alcorlo, Martín; López-Perrote, Andrés; Delgado, Sandra; Yébenes, Hugo; Subías, Marta; Rodríguez-Gallego, César; Rodríguez de Córdoba, Santiago; Llorca, Oscar

    2015-10-01

    The proteolytic cleavage of C3 to generate C3b is the central and most important step in the activation of complement, a major component of innate immunity. The comparison of the crystal structures of C3 and C3b illustrates large conformational changes during the transition from C3 to C3b. Exposure of a reactive thio-ester group allows C3b to bind covalently to surfaces such as pathogens or apoptotic cellular debris. The displacement of the thio-ester-containing domain (TED) exposes hidden surfaces that mediate the interaction with complement factor B to assemble the C3-convertase of the alternative pathway (AP). In addition, the displacement of the TED and its interaction with the macroglobulin 1 (MG1) domain generates an extended surface in C3b where the complement regulators factor H (FH), decay accelerating factor (DAF), membrane cofactor protein (MCP) and complement receptor 1 (CR1) can bind, mediating accelerated decay of the AP C3-convertase and proteolytic inactivation of C3b. In the last few years, evidence has accumulated revealing that the structure of C3b in solution is significantly more flexible than anticipated. We review our current knowledge on C3b structural flexibility to propose a general model where the TED can display a collection of conformations around the MG ring, as well as a few specialized positions where the TED is held in one of several fixed locations. Importantly, this conformational heterogeneity in C3b impacts complement regulation by affecting the interaction with regulators.

  8. Multifractal Scaling, Geometrical Diversity, and Hierarchical Structure in the Cool Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Chappell, David; Scalo, John

    2001-04-01

    Multifractal scaling (MFS) refers to structures that can be described as a collection of interwoven fractal subsets that exhibit power-law spatial-scaling behavior with a range of scaling exponents (concentration, or singularity strengths) and dimensions. The existence of MFS implies an underlying multiplicative (or hierarchical or cascade) process. Panoramic column density images of several nearby star-forming cloud complexes, constructed from IRAS data, are shown to exhibit such multifractal scaling, which we interpret as indirect but quantitative evidence for a nested hierarchical structure. The relation between the dimensions of the subsets and their concentration strengths (the ``multifractal spectrum'') appears to satisfactorily order the observed regions in terms of the mixture of geometries present, from strong pointlike concentrations, to linelike filaments or fronts, to space-filling, diffuse structures. This multifractal spectrum is a global property of the regions studied and does not rely on any operational definition of ``clouds.'' The range of forms of the multifractal spectrum among the regions studied implies that the column density structures do not form a universality class, in contrast to indications for velocity and passive scalar fields in incompressible turbulence, providing another indication that the physics of highly compressible interstellar gas dynamics differs fundamentally from incompressible turbulence. There is no correlation between the geometrical properties of the regions studied and their level of internal star formation activity, a result that is also apparent from visual inspection. We discuss the viability of the multifractal spectrum as a measure of the structural ``complexity'' of the regions studied and emphasize the problematic dependence of all structural descriptors on the subjective preselection of the region to be described. A comparison of IRAS 100 μm column density (not intensity) images with 13CO, visual extinction

  9. MoXy fiber with active cooling cap for bovine prostate vaporization with high power 200W 532 nm laser

    NASA Astrophysics Data System (ADS)

    Peng, Steven Y.; Kang, Hyun Wook; Pirzadeh, Homa; Stinson, Douglas

    2011-03-01

    A novel MoXyTM fiber delivery device with Active Cooling Cap (ACCTM) is designed to transmit up to 180W of 532 nm laser light to treat benign prostatic hyperplasia (BPH). Under such high power tissue ablation, effective cooling is key to maintaining fiber power transmission and ensuring the reliability of the fiber delivery device To handle high power and reduce fiber degradation, the MoXy fiber features a larger core size (750 micrometer) and an internal fluid channel to ensure better cooling of the fiber tip to prevent the cap from burning, detaching, or shattering during the BPH treatment. The internal cooling channel was created with a metal cap and tubing that surrounds the optical fiber. In this study MoXy fibers were used to investigate the effect of power levels of 120 and 200 W on in-vitro bovine prostate ablation using a 532 nm XPSTM laser system. For procedures requiring more than 100 kJ, the MoXy fiber at 200W removed tissue at twice the rate of the current HPS fiber at 120W. The fiber maintained a constant tissue vaporization rate during the entire tissue ablation process. The coagulation at 200W was about 20% thicker than at 120W. In conclusion, the new fibers at 200W doubled the tissue removal rate, maintained vaporization efficiency throughout delivery of 400kJ energy, and induced similar coagulation to the existing HPS fiber at 120W.

  10. 76 FR 22173 - National Pollutant Discharge Elimination System-Cooling Water Intake Structures at Existing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-20

    ...This proposed rule would establish requirements under section 316(b) of the Clean Water Act (CWA) for all existing power generating facilities and existing manufacturing and industrial facilities that withdraw more than 2 million gallons per day (MGD) of water from waters of the U.S. and use at least twenty-five (25) percent of the water they withdraw exclusively for cooling purposes. The......

  11. Cool Sportswear

    NASA Technical Reports Server (NTRS)

    1982-01-01

    New athletic wear design based on the circulating liquid cooling system used in the astronaut's space suits, allows athletes to perform more strenuous activity without becoming overheated. Techni-Clothes gear incorporates packets containing a heat-absorbing gel that slips into an insulated pocket of the athletic garment and is positioned near parts of the body where heat transfer is most efficient. A gel packet is good for about one hour. Easily replaced from a supply of spares in an insulated container worn on the belt. The products, targeted primarily for runners and joggers and any other athlete whose performance may be affected by hot weather, include cooling headbands, wrist bands and running shorts with gel-pack pockets.

  12. Cooling of nanomechanical resonators by thermally activated single-electron transport.

    PubMed

    Santandrea, F; Gorelik, L Y; Shekhter, R I; Jonson, M

    2011-05-06

    We show that the vibrations of a nanomechanical resonator can be cooled to near its quantum ground state by tunneling injection of electrons from a scanning tunneling microscope tip. The interplay between two mechanisms for coupling the electronic and mechanical degrees of freedom results in a bias-voltage-dependent difference between the probability amplitudes for vibron emission and absorption during tunneling. For a bias voltage just below the Coulomb blockade threshold, we find that absorption dominates, which leads to cooling corresponding to an average vibron population of the fundamental bending mode of 0.2.

  13. Cool temperatures reduce antifungal activity of symbiotic bacteria of threatened amphibians--implications for disease management and patterns of decline.

    PubMed

    Daskin, Joshua H; Bell, Sara C; Schwarzkopf, Lin; Alford, Ross A

    2014-01-01

    Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a widespread disease of amphibians responsible for population declines and extinctions. Some bacteria from amphibians' skins produce antimicrobial substances active against Bd. Supplementing populations of these cutaneous antifungal bacteria might help manage chytridiomycosis in wild amphibians. However, the activity of protective bacteria may depend upon environmental conditions. Biocontrol of Bd in nature thus requires knowledge of how environmental conditions affect their anti-Bd activity. For example, Bd-driven amphibian declines have often occurred at temperatures below Bd's optimum range. It is possible these declines occurred due to reduced anti-Bd activity of bacterial symbionts at cool temperatures. Better understanding of the effects of temperature on chytridiomycosis development could also improve risk evaluation for amphibian populations yet to encounter Bd. We characterized, at a range of temperatures approximating natural seasonal variation, the anti-Bd activity of bacterial symbionts from the skins of three species of rainforest tree frogs (Litoria nannotis, Litoria rheocola, and Litoria serrata). All three species declined during chytridiomycosis outbreaks in the late 1980s and early 1990s and have subsequently recovered to differing extents. We collected anti-Bd bacterial symbionts from frogs and cultured the bacteria at constant temperatures from 8 °C to 33 °C. Using a spectrophotometric assay, we monitored Bd growth in cell-free supernatants (CFSs) from each temperature treatment. CFSs from 11 of 24 bacteria showed reduced anti-Bd activity in vitro when they were produced at cool temperatures similar to those encountered by the host species during population declines. Reduced anti-Bd activity of metabolites produced at low temperatures may, therefore, partially explain the association between Bd-driven declines and cool temperatures. We show that to avoid

  14. The excited-state structure, vibrations, lifetimes, and nonradiative dynamics of jet-cooled 1-methylcytosine

    NASA Astrophysics Data System (ADS)

    Trachsel, Maria A.; Wiedmer, Timo; Blaser, Susan; Frey, Hans-Martin; Li, Quansong; Ruiz-Barragan, Sergi; Blancafort, Lluís; Leutwyler, Samuel

    2016-10-01

    We have investigated the S0 → S1 UV vibronic spectrum and time-resolved S1 state dynamics of jet-cooled amino-keto 1-methylcytosine (1MCyt) using two-color resonant two-photon ionization, UV/UV holeburning and depletion spectroscopies, as well as nanosecond and picosecond time-resolved pump/delayed ionization measurements. The experimental study is complemented with spin-component-scaled second-order coupled-cluster and multistate complete active space second order perturbation ab initio calculations. Above the weak electronic origin of 1MCyt at 31 852 cm-1 about 20 intense vibronic bands are observed. These are interpreted as methyl group torsional transitions coupled to out-of-plane ring vibrations, in agreement with the methyl group rotation and out-of-plane distortions upon 1ππ∗ excitation predicted by the calculations. The methyl torsion and ν1 ' (butterfly) vibrations are strongly coupled, in the S1 state. The S0 → S1 vibronic spectrum breaks off at a vibrational excess energy Eexc ˜ 500 cm-1, indicating that a barrier in front of the ethylene-type S1⇝S0 conical intersection is exceeded, which is calculated to lie at Eexc = 366 cm-1. The S1⇝S0 internal conversion rate constant increases from kIC = 2 ṡ 109 s-1 near the S1(v = 0) level to 1 ṡ 1011 s-1 at Eexc = 516 cm-1. The 1ππ∗ state of 1MCyt also relaxes into the lower-lying triplet T1 (3ππ∗) state by intersystem crossing (ISC); the calculated spin-orbit coupling (SOC) value is 2.4 cm-1. The ISC rate constant is 10-100 times lower than kIC; it increases from kISC = 2 ṡ 108 s-1 near S1(v = 0) to kISC = 2 ṡ 109 s-1 at Eexc = 516 cm-1. The T1 state energy is determined from the onset of the time-delayed photoionization efficiency curve as 25 600 ± 500 cm-1. The T2 (3nπ∗) state lies >1500 cm-1 above S1(v = 0), so S1⇝T2 ISC cannot occur, despite the large SOC parameter of 10.6 cm-1. An upper limit to the adiabatic ionization energy of 1MCyt is determined as 8.41 ± 0.02 e

  15. Rho kinase activation and ROS production contributes to the cooling enhanced contraction in cutaneous equine digital veins.

    PubMed

    Zerpa, H; Berhane, Y; Woodcock, H; Elliott, J; Bailey, S R

    2010-07-01

    A decrease in environmental temperature can directly affect the contractility of cutaneous vasculature, mediated in part by alpha(2)-adrenoceptors. Most of the cellular mechanisms underlying the cooling-enhanced contractility to alpha(2)-adrenoceptor agonists have been reported in cutaneous arteries but little information is available on cutaneous veins. To investigate the cellular mechanisms associated with the cooling-enhanced contraction to UK-14304 (alpha(2)-adrenoceptor agonist), isolated equine digital veins (EDVs) were studied at 30 degrees C and 22 degrees C. The effects of inhibitors were studied on the contractile response to UK-14304 (0.1 microM). The cooling-enhanced responses were inhibited by Rho kinase inhibitors [maximum response to UK-14304 95.2 +/- 8% of response to depolarizing Krebs solution (DKS) in control vessels cooled to 22 degrees C, compared with 31.4 +/- 6% in the presence of fasudil 1 microM and 75.8 +/- 6% with Y-27632 0.1 microM] and the effects of these inhibitors were considerably less at 30 degrees C (control response 56.4 +/- 5% of DKS; 34.9 +/- 6% with fasudil 1 microM and 50.6 +/- 9% with Y-27632 0.1 microM). Furthermore, Western blotting showed that one of the downstream targets for Rho kinase activity, ezrin/radixin/moesin, was phosphorylated after cooling and reduced by fasudil (1 microM) only at 22 degrees C. The activation of protein kinase C contributed to the contractile response, but predominantly at 30 degrees C (maximum response 82.3 +/- 9% of DKS for control; 57.7 +/- 10% in the presence of chelerythrine 10 microM) with no significant effect at 22 degrees C. The reduction of the response at 22 degrees C by antioxidants, rotenone (14% reduction), and tempol (21% reduction) suggested the contribution of reactive oxygen species (ROS). No evidence was obtained to support the participation of tyrosine kinase. These data demonstrate that Rho kinase activation and the production of ROS contributes to the cooling

  16. 75 FR 52734 - Agency Information Collection Activities; Submission to OMB for Review and Approval; Cooling...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-27

    ... location, design, construction and capacity of CWISs at that facility reflect the best technology available... establishes requirements applicable to the location, design, construction, and capacity of CWISs at Phase II... withdraws from waters of the U.S. for cooling purposes, and have a design intake flow of 50 million...

  17. Epicyclic Twin-helix Magnetic Structure for Parametric-resonance Ionization Cooling

    SciTech Connect

    A. Afanasev, R.P. Johnson, Y.S. Derbenev, V.S. Morozov

    2010-05-01

    Para­met­ric-res­o­nance Ion­iza­tion Cool­ing (PIC) is en­vi­sioned as the final 6D cool­ing stage of a high-lu­mi­nos­i­ty muon col­lid­er. Im­ple­ment­ing PIC im­pos­es strin­gent con­straints on the cool­ing chan­nel's mag­net­ic op­tics de­sign. This paper pre­sents a lin­ear op­tics so­lu­tion com­pat­i­ble with PIC. Our so­lu­tion con­sists of a su­per­po­si­tion of two op­po­site-he­lic­i­ty equal-pe­ri­od and equal-strength he­li­cal dipole har­mon­ics and a straight nor­mal quadrupole. We demon­strate that such a sys­tem can be ad­just­ed to meet all of the PIC lin­ear op­tics re­quire­ments while re­tain­ing large ac­cep­tance.

  18. Stochastic Cooling

    SciTech Connect

    Blaskiewicz, M.

    2011-01-01

    Stochastic Cooling was invented by Simon van der Meer and was demonstrated at the CERN ISR and ICE (Initial Cooling Experiment). Operational systems were developed at Fermilab and CERN. A complete theory of cooling of unbunched beams was developed, and was applied at CERN and Fermilab. Several new and existing rings employ coasting beam cooling. Bunched beam cooling was demonstrated in ICE and has been observed in several rings designed for coasting beam cooling. High energy bunched beams have proven more difficult. Signal suppression was achieved in the Tevatron, though operational cooling was not pursued at Fermilab. Longitudinal cooling was achieved in the RHIC collider. More recently a vertical cooling system in RHIC cooled both transverse dimensions via betatron coupling.

  19. Structure interaction due to thermal bowing of shrouds in steam generator of gas-cooled reactor

    SciTech Connect

    Woo, H.H.

    1981-01-01

    The design of the gas-cooled reactor steam generators includes a tube bundle support plate system which restrains and supports the helical tubes in the steam generator. The support system consists of an array of radially oriented, perforated plates through which the helical tube coils are wound. These support plates have tabs on their edges which fit into vertical slots in the inner and outer shrouds. When the helical tube bundle and support plates are installed in the steam generator, they most likely cannot fit evenly between the inner and outer shrouds. This imperfection leads to different gaps between two extreme sides of the tube bundle and the shrouds. With different gaps through the tube bundle height, the helium flow experiences different cooling effects from the tube bundle. Hence, the temperature distribution in the shrouds will be non-uniform circumferentially since their surrounding helium flow temperatures are varied. These non-uniform temperatures in the shrouds result in the phenomenon of thermal bowing of shrouds.

  20. Active Cells for Multifunctional Structures

    DTIC Science & Technology

    2014-09-24

    techniques to explore a variety of cell designs.  Designed a simplified active cell using Nitinol as the actuation method and relying on Joule heating...for contraction of the cell.  Developed manufacturing techniques for reliably creating Nitinol spring coils in a variety of diameters and gauges...design of the active cells to maximum the stroked length of the active cells by tuning the stiffness of a passive spring in parallel with the Nitinol

  1. A Thermal Physiological Comparison of Two HazMat Protective Ensembles With and Without Active Convective Cooling

    NASA Technical Reports Server (NTRS)

    Williamson, Rebecca; Carbo, Jorge; Luna, Bernadette; Webbon, Bruce W.

    1998-01-01

    Wearing impermeable garments for hazardous materials clean up can often present a health and safety problem for the wearer. Even short duration clean up activities can produce heat stress injuries in hazardous materials workers. It was hypothesized that an internal cooling system might increase worker productivity and decrease likelihood of heat stress injuries in typical HazMat operations. Two HazMat protective ensembles were compared during treadmill exercise. The different ensembles were created using two different suits: a Trelleborg VPS suit representative of current HazMat suits and a prototype suit developed by NASA engineers. The two life support systems used were a current technology Interspiro Spirolite breathing apparatus and a liquid air breathing system that also provided convective cooling. Twelve local members of a HazMat team served as test subjects. They were fully instrumented to allow a complete physiological comparison of their thermal responses to the different ensembles. Results showed that cooling from the liquid air system significantly decreased thermal stress. The results of the subjective evaluations of new design features in the prototype suit were also highly favorable. Incorporation of these new design features could lead to significant operational advantages in the future.

  2. The Herschel Comprehensive (U)LIRG Emission Survey (HERCULES): CO Ladders, Fine Structure Lines, and Neutral Gas Cooling

    NASA Astrophysics Data System (ADS)

    Rosenberg, M. J. F.; van der Werf, P. P.; Aalto, S.; Armus, L.; Charmandaris, V.; Díaz-Santos, T.; Evans, A. S.; Fischer, J.; Gao, Y.; González-Alfonso, E.; Greve, T. R.; Harris, A. I.; Henkel, C.; Israel, F. P.; Isaak, K. G.; Kramer, C.; Meijerink, R.; Naylor, D. A.; Sanders, D. B.; Smith, H. A.; Spaans, M.; Spinoglio, L.; Stacey, G. J.; Veenendaal, I.; Veilleux, S.; Walter, F.; Weiß, A.; Wiedner, M. C.; van der Wiel, M. H. D.; Xilouris, E. M.

    2015-03-01

    (Ultra) luminous infrared galaxies ((U)LIRGs) are objects characterized by their extreme infrared (8-1000 μm) luminosities (L LIRG > 1011 L ⊙ and L ULIRG > 1012 L ⊙). The Herschel Comprehensive ULIRG Emission Survey (PI: van der Werf) presents a representative flux-limited sample of 29 (U)LIRGs that spans the full luminosity range of these objects (1011 L ⊙ <= L IR <= 1013 L ⊙). With the Herschel Space Observatory, we observe [C II] 157 μm, [O I] 63 μm, and [O I] 145 μm line emission with Photodetector Array Camera and Spectrometer, CO J = 4-3 through J = 13-12, [C I] 370 μm, and [C I] 609 μm with SPIRE, and low-J CO transitions with ground-based telescopes. The CO ladders of the sample are separated into three classes based on their excitation level. In 13 of the galaxies, the [O I] 63 μm emission line is self absorbed. Comparing the CO excitation to the InfraRed Astronomical Satellite 60/100 μm ratio and to far infrared luminosity, we find that the CO excitation is more correlated to the far infrared colors. We present cooling budgets for the galaxies and find fine-structure line flux deficits in the [C II], [Si II], [O I], and [C I] lines in the objects with the highest far IR fluxes, but do not observe this for CO 4 <= J upp <= 13. In order to study the heating of the molecular gas, we present a combination of three diagnostic quantities to help determine the dominant heating source. Using the CO excitation, the CO J = 1-0 linewidth, and the active galactic nucleus (AGN) contribution, we conclude that galaxies with large CO linewidths always have high-excitation CO ladders, and often low AGN contributions, suggesting that mechanical heating is important. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  3. Variability in cold front activities modulating cool-season evaporation from a southern inland water in the USA

    NASA Astrophysics Data System (ADS)

    Liu, Heping; Blanken, Peter D.; Weidinger, Tamas; Nordbo, Annika; Vesala, Timo

    2011-04-01

    Understanding seasonal variations in the evaporation of inland waters (e.g., lakes and reservoirs) is important for water resource management as well as the prediction of the hydrological cycles in response to climate change. We analyzed eddy covariance-based evaporation measurements from the Ross Barnett Reservoir (32°26'N, 90°02'W which is always ice-free) in central Mississippi during the cool months (i.e., September-March) of 2007 and 2008, and found that the variability in cold front activities (i.e., passages of cold fronts and cold/dry air masses behind cold fronts) played an important role in modulating the exchange of sensible (H) and latent (λE) heat fluxes. Our analysis showed that 2007's warmer cool season had smaller mean H and λE than 2008's cooler cool season. This implies that the warmer cool season did not accelerate evaporation and heat exchange between the water surface and the atmosphere. Instead, more frequent cold fronts and longer periods of cold/dry air masses behind the cold fronts in 2008 resulted in overall larger H and λE as compared with 2007, this primarily taking the form of sporadic short-term rapid 'pulses' of H and λE losses from the water's surface. These results suggest that future climate-induced changes in frequency of cold fronts and the meteorological properties of the air masses behind cold fronts (e.g., wind speeds, temperature, and humidity), rather than other factors of climate change, would produce significant variations in the water surface's energy fluxes and subsequent evaporation rates.

  4. The influence of cooling on the advance of lava flows: insights from analogue experiments on the feedbacks between flow dynamics and thermal structure

    NASA Astrophysics Data System (ADS)

    Garel, F.; Kaminski, E.; Tait, S.; Limare, A.

    2012-12-01

    During an effusive volcanic eruption, the crisis management is mainly based on the prediction of lava flows advance and its velocity. The spreading of a lava flow, seen as a gravity current, depends on its "effective rheology" and the eruptive mass flux. These two parameters are not known a priori during an eruption and a key question is how to evaluate them in near real-time (rather than afterwards.) There is no generic macroscopic model for the rheology of an advancing lava flow, and analogue modelling is a precious tool to empirically estimate the rheology of a complex flow. We investigate through laboratory experiments the simultaneous spreading and cooling of horizontal currents fed at constant rate from a point source. The materials used are silicone oil (isoviscous), and poly-ethylene glycol (PEG) wax injected in liquid state and solidiying during its advance. In the isoviscous case, the temperature field is a passive tracer of the flow dynamics, whereas in the PEG experiments there is a feedback between the cooling of the flow and its effective rheology. We focus on the evolution of the current area and of the surface thermal structure, imaged with an infrared camera, to assess how the thermal structure can be related to the flow rate. The flow advance is continuous in the viscous case, and follows the predictions of Huppert (1982); in that case the surface temperature become steady after a transient time and the radiated heat flux is shown to be proportional to the input rate. For the PEG experiments, the spreading occurs through an alternation of stagnation and overflow phases, with a mean spreading rate decreasing as the experiment goes on. As in the case of lava flows, these experiments can exhibit a compound flow field, solid levees, thermal erosion, liquid overflows and channelization. A key observation is that the effective rheology of the solifying PEG material depends on the input flow rate, with high input rates yielding a rheology closer to the

  5. Warm and Cool Dinosaurs.

    ERIC Educational Resources Information Center

    Mannlein, Sally

    2001-01-01

    Presents an art activity in which first grade students draw dinosaurs in order to learn about the concept of warm and cool colors. Explains how the activity also helped the students learn about the concept of distance when drawing. (CMK)

  6. Active impedance matching of complex structural systems

    NASA Technical Reports Server (NTRS)

    Macmartin, Douglas G.; Miller, David W.; Hall, Steven R.

    1991-01-01

    Viewgraphs on active impedance matching of complex structural systems are presented. Topics covered include: traveling wave model; dereverberated mobility model; computation of dereverberated mobility; control problem: optimal impedance matching; H2 optimal solution; statistical energy analysis (SEA) solution; experimental transfer functions; interferometer actuator and sensor locations; active strut configurations; power dual variables; dereverberation of complex structure; dereverberated transfer function; compensators; and relative power flow.

  7. Research on cooling effectiveness in stepped slot film cooling vane

    NASA Astrophysics Data System (ADS)

    Li, Yulong; Wu, Hong; Zhou, Feng; Rong, Chengjun

    2016-06-01

    As one of the most important developments in air cooling technology for hot parts of the aero-engine, film cooling technology has been widely used. Film cooling hole structure exists mainly in areas that have high temperature, uneven cooling effectiveness issues when in actual use. The first stage turbine vanes of the aero-engine consume the largest portion of cooling air, thereby the research on reducing the amount of cooling air has the greatest potential. A new stepped slot film cooling vane with a high cooling effectiveness and a high cooling uniformity was researched initially. Through numerical methods, the affecting factors of the cooling effectiveness of a vane with the stepped slot film cooling structure were researched. This paper focuses on the cooling effectiveness and the pressure loss in different blowing ratio conditions, then the most reasonable and scientific structure parameter can be obtained by analyzing the results. The results show that 1.0 mm is the optimum slot width and 10.0 is the most reasonable blowing ratio. Under this condition, the vane achieved the best cooling result and the highest cooling effectiveness, and also retained a low pressure loss.

  8. Structural Antitumoral Activity Relationships of Synthetic Chalcones

    PubMed Central

    Echeverria, Cesar; Santibañez, Juan Francisco; Donoso-Tauda, Oscar; Escobar, Carlos A.; Ramirez-Tagle, Rodrigo

    2009-01-01

    Relationships between the structural characteristic of synthetic chalcones and their antitumoral activity were studied. Treatment of HepG2 cells for 24 h with synthetic 2’-hydroxychalcones resulted in apoptosis induction and dose-dependent inhibition of cell proliferation. The calculated reactivity indexes and the adiabatic electron affinities using the DFT method including solvent effects, suggest a structure-activity relationship between the Chalcones structure and the apoptosis in HepG2 cells. The absence of methoxy substituents in the B ring of synthetic 2’-hydroxychalcones, showed the mayor structure-activity pattern along the series. PMID:19333443

  9. Study of a fail-safe abort system for an actively cooled hypersonic aircraft: Computer program documentation

    NASA Technical Reports Server (NTRS)

    Haas, L. A., Sr.

    1976-01-01

    The Fail-Safe Abort System TEMPerature Analysis Program, (FASTEMP), user's manual is presented. This program was used to analyze fail-safe abort systems for an actively cooled hypersonic aircraft. FASTEMP analyzes the steady state or transient temperature response of a thermal model defined in rectangular, cylindrical, conical and/or spherical coordinate system. FASTEMP provides the user with a large selection of subroutines for heat transfer calculations. The various modes of heat transfer available from these subroutines are: heat storage, conduction, radiation, heat addition or generation, convection, and fluid flow.

  10. Cooling rate dependence of structural order in Al90Sm10 metallic glass

    SciTech Connect

    Sun, Yang; Zhang, Yue; Zhang, Feng; Ye, Zhuo; Ding, Zejun; Wang, Cai -Zhuang; Ho, Kai -Ming

    2016-07-07

    Here, the atomic structure of Al90Sm10 metallic glass is studied using molecular dynamics simulations. By performing a long sub-Tg annealing, we developed a glass model closer to the experiments than the models prepared by continuous cooling. Using the cluster alignment method, we found that “3661” cluster is the dominating short-range order in the glass samples. The connection and arrangement of “3661” clusters, which define the medium-range order in the system, are enhanced significantly in the sub-Tg annealed sample as compared with the fast cooled glass samples. Unlike some strong binary glass formers such as Cu64.5Zr35.5, the clusters representing the short-range order do not form an interconnected interpenetrating network in Al90Sm10, which has only marginal glass formability.

  11. Enhancement of Nucleate Boiling Heat Flux on Macro/Micro-Structured Surfaces Cooled by Multiple Impinging Jets

    NASA Technical Reports Server (NTRS)

    Kugler, Scott Lee

    1997-01-01

    An experimental investigation of nucleate boiling heat transfer from modified surfaces cooled by multiple in-line impinging circular jets is reported and found to agree with single jet results. A copper block is heated from the back by two electrical arcs, and cooled on the opposite side by three identical liquid jets of distilled water at subcoolings of 25 C 50 C and 77 C and Freon 113 at 24 C subcooling. Liquid flow rates are held constant at 5, 10, and 15 GPH for each of the three jets with jet velocities ranging from 1.4 m/s to 1 1.2 m/s and jet diameters from 0.95 mm to 2.2 mm. To increase the maximum heat flux (CHF) and heat removal rate, the boiling surface was modified by both macro and micro enhancements. Macro modification consists of machined radial grooves in the boiling surface arranged in an optimally designed pattern to allow better liquid distribution along the surface. These grooves also reduce splashing of liquid droplets, and provide 'channels' to sweep away bubbles. Micro modification was achieved by flame spraying metal powder on the boiling surface, creating a porous, sintered surface. With the addition of both micro and macro structured enhancements, maximum heat flux and nucleate boiling can be enhanced by more than 200%. Examination of each surface modification separately and together indicates that at lower superheats, the micro structure provides the enhanced heat transfer by providing more nucleation sites, while for higher superheats the macro structure allows better liquid distribution and bubble removal. A correlation is presented to account for liquid subcoolings and surface enhancements, in addition to the geometrical and fluid properties previously reported in the literature.

  12. Is magma cooling responsible for the periodic activity of Soufrière Hills volcano, Montserrat, West Indies?

    NASA Astrophysics Data System (ADS)

    Caricchi, Luca; Simpson, Guy; Chelle-Michou, Cyril; Neuberg, Jürgen

    2016-04-01

    After 400 years of quiescence, Soufrière Hills volcano on Montserrat (SHV) started erupting in 1995. Ongoing deformation and sulphur dioxide emission demonstrate that this volcanic systems is still restless, however, after 5 years of inactivity it remains unclear whether magma extrusion will restart. Also, if such periodically observed activity at SHV will restart, can we use past monitoring data to attempt to forecast the reawakening of this volcano? Cooling of volatile saturated magma leads to crystallisation, the formation of gas bubbles and expansion. Such volumetric variations are not only potentially responsible for deformation signals observed at the surface (Caricchi et al., 2014), but also lead to pressurisation of the magmatic reservoir and eventually renewed magma extrusion (Tait et al., 1989). We postulate that volcanic activity observed at SHM over the last 20 years could be essentially the result of the unavoidable progressive cooling of a magmatic body, which was probably assembled over thousands of years and experienced internal segregation of eruptible lenses of magma (Christopher et al., 2015). To test this hypothesis, we performed thermal modelling to test if the cooling of a shallow magma body emplaced since 1990 could account for the monitoring signals observed at SHV. The results show that progressive cooling of a 4km3 volume of melt could explain the deformation rate currently observed. Using the deformation rate obtained from the modelling for the first 15 years of cooling, a reservoir volume of about 13 km3 (Paulatto et al., 2012) and a critical value of overpressure of 10 MPa, it would have taken approximately only 3 years to pressurise the reservoir to the critical pressure and restart magma extrusion. This is in agreement with the time interval between previous pauses at SHV before 2010. Considering the current deformation rates, we speculate that magma extrusion could restart in 6-8 years after the end of the last event in 2010, hence

  13. Regional and total body active heating and cooling of a resting diver in water of varied temperatures

    NASA Astrophysics Data System (ADS)

    Bardy, Erik; Mollendorf, Joseph; Pendergast, David

    2008-02-01

    Passive insulations alone are not sufficient for maintaining underwater divers in thermal balance or comfort. The purpose of this study was to experimentally determine the active heating and cooling requirements to keep a diver at rest in thermal balance and comfort in water temperatures between 10 and 40 °C. A diver wearing a prototype tubesuit and a wetsuit (3 or 6.5 mm foam neoprene) was fully submersed (0.6 m) in water at a specified temperature (10, 20, 30 and 40 °C). During immersion, the tubesuit was perfused with 30 °C water at a flow rate of 0.5 L min-1 to six individual body regions. An attempt was made to keep skin temperatures below 42 °C in hot water (>30 °C) and elevated but below 32 °C in cold water (<20 °C). A skin temperature of 32 °C is the threshold for maximal body thermal resistance due to vasoconstriction. Skin temperatures and core temperature were monitored during immersion to ensure they remained within set thermal limits. In addition skin heat flux, oxygen consumption and the thermal exchange of the tubesuit were measured. In both wetsuit thicknesses there was a linear correlation between the thermal exchange of the tubesuit and ambient water temperature. In the 6.5 mm wetsuit -214 W to 242 W of heating (-) and cooling (+) was necessary in 10 °C to 40 °C water, respectively. In the 3 mm wetsuit -462 to 342 W was necessary in 10 °C to 40 °C water, respectively. It was therefore concluded that a diver at rest can be kept in thermal balance in 10-40 °C water with active heating and cooling.

  14. High energy electron cooling

    SciTech Connect

    Parkhomchuk, V.

    1997-09-01

    High energy electron cooling requires a very cold electron beam. The questions of using electron cooling with and without a magnetic field are presented for discussion at this workshop. The electron cooling method was suggested by G. Budker in the middle sixties. The original idea of the electron cooling was published in 1966. The design activities for the NAP-M project was started in November 1971 and the first run using a proton beam occurred in September 1973. The first experiment with both electron and proton beams was started in May 1974. In this experiment good result was achieved very close to theoretical prediction for a usual two component plasma heat exchange.

  15. AHA! A Cool Salt Water/Density Activity--The Joy of Designing a Simple Experiment.

    ERIC Educational Resources Information Center

    Carlson, Gaylen R.

    1998-01-01

    Describes two science activities concerning water density and shares an idea for combining these activities into a third, completely new activity. Demonstrates the joy of rekindling the spirit of scientific thinking in a typical classroom. (PVD)

  16. Modular jet impingement assemblies with passive and active flow control for electronics cooling

    DOEpatents

    Zhou, Feng; Dede, Ercan Mehmet; Joshi, Shailesh

    2016-09-13

    Power electronics modules having modular jet impingement assembly utilized to cool heat generating devices are disclosed. The modular jet impingement assemblies include a modular manifold having a distribution recess, one or more angled inlet connection tubes positioned at an inlet end of the modular manifold that fluidly couple the inlet tube to the distribution recess and one or more outlet connection tubes positioned at an outlet end of the modular manifold that fluidly coupling the outlet tube to the distribution recess. The modular jet impingement assemblies include a manifold insert removably positioned within the distribution recess and include one or more inlet branch channels each including an impinging slot and one or more outlet branch channels each including a collecting slot. Further a heat transfer plate coupled to the modular manifold, the heat transfer plate comprising an impingement surface including an array of fins that extend toward the manifold insert.

  17. Harvesting and cryo-cooling crystals of membrane proteins grown in lipidic mesophases for structure determination by macromolecular crystallography.

    PubMed

    Li, Dianfan; Boland, Coilín; Aragao, David; Walsh, Kilian; Caffrey, Martin

    2012-09-02

    An important route to understanding how proteins function at a mechanistic level is to have the structure of the target protein available, ideally at atomic resolution. Presently, there is only one way to capture such information as applied to integral membrane proteins (Figure 1), and the complexes they form, and that method is macromolecular X-ray crystallography (MX). To do MX diffraction quality crystals are needed which, in the case of membrane proteins, do not form readily. A method for crystallizing membrane proteins that involves the use of lipidic mesophases, specifically the cubic and sponge phases(1-5), has gained considerable attention of late due to the successes it has had in the G protein-coupled receptor field(6-21) (www.mpdb.tcd.ie). However, the method, henceforth referred to as the in meso or lipidic cubic phase method, comes with its own technical challenges. These arise, in part, due to the generally viscous and sticky nature of the lipidic mesophase in which the crystals, which are often micro-crystals, grow. Manipulating crystals becomes difficult as a result and particularly so during harvesting(22,23). Problems arise too at the step that precedes harvesting which requires that the glass sandwich plates in which the crystals grow (Figure 2)(24,25) are opened to expose the mesophase bolus, and the crystals therein, for harvesting, cryo-cooling and eventual X-ray diffraction data collection. The cubic and sponge mesophase variants (Figure 3) from which crystals must be harvested have profoundly different rheologies(4,26). The cubic phase is viscous and sticky akin to a thick toothpaste. By contrast, the sponge phase is more fluid with a distinct tendency to flow. Accordingly, different approaches for opening crystallization wells containing crystals growing in the cubic and the sponge phase are called for as indeed different methods are required for harvesting crystals from the two mesophase types. Protocols for doing just that have been

  18. Differential rotation of cool active stars: the case of intermediate rotators

    NASA Astrophysics Data System (ADS)

    Petit, P.; Donati, J.-F.; Collier Cameron, A.

    2002-08-01

    In this paper, we present a new method for measuring the surface differential rotation of cool stars with rotation periods of a few days, for which the sparse phase coverage achievable from single-site observations generally prevents the use of more conventional techniques. The basic idea underlying this new analysis is to obtain the surface differential rotation pattern that minimizes the information content of the reconstructed Doppler image through a simultaneous fit of all available data. Simulations demonstrate that the performance of this new method in the case of cool stars is satisfactory for a variety of observing strategies. Differential rotation parameters can be recovered reliably as long as the total data set spans at least 4 per cent of the time for the equator to lap the pole by approximately one complete cycle. We find in particular that these results hold for potentially complex spot distributions (as long as they include a mixture of low- and high-latitude features), and for various stellar inclination angles and rotation velocities. Such measurements can be obtained from either unpolarized or polarized data sets, provided their signal-to-noise ratio is larger than approximately 500 and 5000 per 2kms-1 spectral bin, respectively. This method should therefore be very useful for investigating differential rotation in a much larger sample of objects than what has been possible up to now, and should hence give us the opportunity of studying how differential rotation reacts to various phenomena operating in stellar convective zones, such as tidal effects or dynamo magnetic field generation.

  19. Cooling dissociates glucose-induced insulin release from electrical activity and cation fluxes in rodent pancreatic islets.

    PubMed Central

    Atwater, I; Goncalves, A; Herchuelz, A; Lebrun, P; Malaisse, W J; Rojas, E; Scott, A

    1984-01-01

    Insulin release and beta-cell membrane potentials in response to glucose at 37 and 27 degrees C have been measured simultaneously in single, micro-dissected, perifused islets of Langerhans from normal mice. Insulin release and 45Ca outflow in response to glucose at 37 and 27 degrees C have been measured simultaneously from perfused islets isolated by collagenase digestion from normal rats. The effect of cooling on beta-cell membrane potassium permeability was assessed by changes in measured membrane potential and input resistance (in the mouse) and by changes in 86Rb outflow (in the rat). Resting and active beta-cell membrane parameters (i.e. membrane potential, spike frequency, input resistance, 45Ca outflow and 86Rb outflow), in both mouse and rat islets, were affected only slightly by cooling to 27 degrees C, with temperature coefficients of 2 or lower. At 27 degrees C glucose-stimulated insulin release was inhibited completely in mouse islets and almost completely in rat islets. The temperature coefficients in both preparations were greater than 5. It is concluded that beta-cell electrical activity and changes in membrane permeability induced by glucose are not consequences of insulin release. PMID:6371219

  20. Large-Scale Coronal Heating from "Cool" Activity in the Solar Magnetic Network

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.

    1999-01-01

    In Fe XII images from SOHO/EIT, the quiet solar corona shows structure on scales ranging from sub-supergranular (i.e., bright points and coronal network) to multi-supergranular (large-scale corona). In Falconer et al 1998 (Ap.J., 501, 386) we suppressed the large-scale background and found that the network-scale features are predominantly rooted in the magnetic network lanes at the boundaries of the supergranules. Taken together, the coronal network emission and bright point emission are only about 5% of the entire quiet solar coronal Fe XII emission. Here we investigate the relationship between the large-scale corona and the network as seen in three different EIT filters (He II, Fe IX-X, and Fe XII). Using the median-brightness contour, we divide the large-scale Fe XII corona into dim and bright halves, and find that the bright-half/dim half brightness ratio is about 1.5. We also find that the bright half relative to the dim half has 10 times greater total bright point Fe XII emission, 3 times greater Fe XII network emission, 2 times greater Fe IX-X network emission, 1.3 times greater He II network emission, and has 1.5 times more magnetic flux. Also, the cooler network (He II) radiates an order of magnitude more energy than the hotter coronal network (Fe IX-X, and Fe XII). From these results we infer that: 1) The heating of the network and the heating of the large-scale corona each increase roughly linearly with the underlying magnetic flux. 2) The production of network coronal bright points and heating of the coronal network each increase nonlinearly with the magnetic flux. 3) The heating of the large-scale corona is driven by widespread cooler network activity rather than by the exceptional network activity that produces the network coronal bright points and the coronal network. 4) The large-scale corona is heated by a nonthermal process since the driver of its heating is cooler than it is. This work was funded by the Solar Physics Branch of NASA's office of

  1. Infrared laser spectroscopy of jet-cooled carbon clusters: structure of triplet C6

    NASA Technical Reports Server (NTRS)

    Hwang, H. J.; Van Orden, A.; Tanaka, K.; Kuo, E. W.; Heath, J. R.; Saykally, R. J.

    1993-01-01

    We report the first structural characterization of the triplet isomer of C6. Forty-one rovibrational/fine structure transitions in the nu 4(sigma u) antisymmetric stretch fundamental of the C6 cluster have been measured by diode laser absorption spectroscopy of a supersonic carbon cluster beam. The observed spectrum is characteristic of a centrosymmetric linear triplet state with cumulene-type bonding. The measured ground state rotational constant B0 = 0.048 479 (10)cm-1 and the effective bond length r(eff) = 1.2868 (1) angstroms are in good agreement with ab initio predictions for the linear triplet (3 sigma g-) state of C6.

  2. Experimental analysis of regularly structured composite latent heat storages for temporary cooling of electronic components

    NASA Astrophysics Data System (ADS)

    Lohse, Ekkehard; Schmitz, Gerhard

    2013-11-01

    This study presents the experimental investigation of regularly structured Composite Latent Heat Storages. Solid-liquid Phase Change Materials have a low thermal conductivity, resulting in high temperature differences. This drawback is compensated by the combination with specially designed frame-structures made of aluminum to enhance the transport of thermal energy. A prototype is investigated experimentally on a test rig, where the heat load and temperatures are measured while the phase change process is observed optically, and compared to a solid block Phase Change Material.

  3. Excited-state structure, vibrations, and nonradiative relaxation of jet-cooled 5-fluorocytosine.

    PubMed

    Lobsiger, Simon; Trachsel, Maria A; Den, Takuya; Leutwyler, Samuel

    2014-03-20

    The S0 → S1 vibronic spectrum and S1 state nonradiative relaxation of jet-cooled keto-amino 5-fluorocytosine (5FCyt) are investigated by two-color resonant two-photon ionization spectroscopy at 0.3 and 0.05 cm(–1) resolution. The 0(0)(0) rotational band contour is polarized in-plane, implying that the electronic transition is (1)ππ*. The electronic transition dipole moment orientation and the changes of rotational constants agree closely with the SCS-CC2 calculated values for the (1)ππ* (S1) transition of 5FCyt. The spectral region from 0 to 300 cm(–1) is dominated by overtone and combination bands of the out-of-plane ν1′ (boat), ν2′ (butterfly), and ν3′ (HN–C6H twist) vibrations, implying that the pyrimidinone frame is distorted out-of-plane by the (1)ππ* excitation, in agreement with SCS-CC2 calculations. The number of vibronic bands rises strongly around +350 cm(–1); this is attributed to the (1)ππ* state barrier to planarity that corresponds to the central maximum of the double-minimum out-of-plane vibrational potentials along the ν1′, ν2′, and ν3′ coordinates, which gives rise to a high density of vibronic excitations. At +1200 cm(–1), rapid nonradiative relaxation (k(nr) ≥ 10(12) s(–1)) sets in, which we interpret as the height of the (1)ππ* state barrier in front of the lowest S1/S0 conical intersection. This barrier in 5FCyt is 3 times higher than that in cytosine. The lifetimes of the ν′ = 0, 2ν1′, 2ν2′, 2ν1′ + 2ν2′, 4ν2′, and 2ν1′ + 4ν2′ levels are determined from Lorentzian widths fitted to the rotational band contours and are τ ≥ 75 ps for ν′ = 0, decreasing to τ ≥ 55 ps at the 2ν1′ + 4ν2′ level at +234 cm(–1). These gas-phase lifetimes are twice those of S1 state cytosine and 10–100 times those of the other canonical nucleobases in the gas phase. On the other hand, the 5FCyt gas-phase lifetime is close to the 73 ps lifetime in room-temperature solvents. This lack of

  4. Activities at the Smart Structures Research Institute

    NASA Astrophysics Data System (ADS)

    Gardiner, Peter T.

    1991-12-01

    Smart Structures and Materials technology will undoubtedly yield a wide range of new materials plus new sensing and actuation technologies and this will have a radical effect on current approaches to structural design. To meet the multi-disciplinary research challenge posed by this technology, the Smart Structures Research Institute (SSRI) has been established at the University of Strathclyde, Glasgow. This paper describes the background, current and planned activities and progress made in developing this new and very promising technology.

  5. Phosphorylation of the cool-1/beta-Pix protein serves as a regulatory signal for the migration and invasive activity of Src-transformed cells.

    PubMed

    Feng, Qiyu; Baird, Dan; Yoo, Sungsoo; Antonyak, Marc; Cerione, Richard A

    2010-06-11

    Previously we showed that Cool-1 (Cloned out of library-1)/beta-Pix (Pak-interactive exchange factor) is phosphorylated at a specific tyrosine residue (Tyr-442) in a Src-dependent manner and serves as a dual function guanine nucleotide exchange factor (GEF)/signaling-effector for Cdc42 that is essential for transformation by Src. Here, we show that knocking-down Cool-1 or overexpressing a Cool-1 mutant that contains substitutions within its Dbl homology domain and is defective for GEF activity, inhibits Src-promoted cell migration. Similarly, the expression of a Cool-1 mutant containing a tyrosine to phenylalanine substitution at position 442, making it incapable of being phosphorylated in response to serum, epidermal growth factor (EGF), or Src, also causes a significant inhibition of the migration and invasive activity of cells expressing oncogenic Src. We further demonstrate that the phosphorylation of Cool-1 at Tyr-442 weakens its ability to bind to one of its primary interaction-partners, Cat-1 (Cool-associated tyrosine phosphosubstrate-1)/Git-1 (G protein-coupled receptor kinase-interactor-1), thus making Cat more accessible for binding to paxillin. This enables cells to alternate between states where they contain large numbers of focal complexes (i.e. conditions favoring Cool-1-Cat interactions) versus reduced numbers of focal complexes (conditions favoring Cat-paxillin interactions). Overall, these findings show that the phosphorylation-dephosphorylation cycle of Cool-1 at Tyr-442 can serve as a key regulatory signal for focal complex assembly-disassembly, and consequently, for the migration and invasive activity of Src-transformed cells.

  6. Active region coronal loops - Structural and variability

    NASA Technical Reports Server (NTRS)

    Haisch, Bernhard M.; Strong, Keith T.; Harrison, Richard A.; Gary, G. A.

    1988-01-01

    X-ray images of a pair of active region loops are studied which show significant, short time-scale variability in the line fluxes of O VIII, Ne IX, and Mg XI and in the 3.5-11.5 keV soft X-ray bands. Vector magnetograms and high-resolution UV images were used to model the three-dimensional characteristics of the loops. X-ray light curves were generated spanning four consecutive orbits for both loops individually, and light curves of the loop tops and brightest points were also generated. The largest variations involve flux changes of up to several hundred percent on time scales of 10 minutes. No significant H-alpha flare activity is reported, and loop temperatures remain in the four to six million K range. The decay phases of the light curves indicate radiative cooling, inhibition of conduction, and some type of 'continued heating' due to ongoing, underlying activity at the microflare level.

  7. Transient heat transfer behavior of water spray evaporative cooling on a stainless steel cylinder with structured surface for safety design application in high temperature scenario

    NASA Astrophysics Data System (ADS)

    Aamir, Muhammad; Liao, Qiang; Hong, Wang; Xun, Zhu; Song, Sihong; Sajid, Muhammad

    2017-02-01

    High heat transfer performance of spray cooling on structured surface might be an additional measure to increase the safety of an installation against any threat caused by rapid increase in the temperature. The purpose of present experimental study is to explore heat transfer performance of structured surface under different spray conditions and surface temperatures. Two cylindrical stainless steel samples were used, one with pyramid pins structured surface and other with smooth surface. Surface heat flux of 3.60, 3.46, 3.93 and 4.91 MW/m2 are estimated for sample initial average temperature of 600, 700, 800 and 900 °C, respectively for an inlet pressure of 1.0 MPa. A maximum cooling rate of 507 °C/s was estimated for an inlet pressure of 0.7 MPa at 900 °C for structured surface while for smooth surface maximum cooling rate of 356 °C/s was attained at 1.0 MPa for 700 °C. Structured surface performed better to exchange heat during spray cooling at initial sample temperature of 900 °C with a relative increase in surface heat flux by factor of 1.9, 1.56, 1.66 and 1.74 relative to smooth surface, for inlet pressure of 0.4, 0.7, 1.0 and 1.3 MPa, respectively. For smooth surface, a decreasing trend in estimated heat flux is observed, when initial sample temperature was increased from 600 to 900 °C. Temperature-based function specification method was utilized to estimate surface heat flux and surface temperature. Limited published work is available about the application of structured surface spray cooling techniques for safety of stainless steel structures at very high temperature scenario such as nuclear safety vessel and liquid natural gas storage tanks.

  8. Structural optimization of an asymmetric automotive brake disc with cooling channels to avoid squeal

    NASA Astrophysics Data System (ADS)

    Wagner, Andreas; Spelsberg-Korspeter, Gottfried; Hagedorn, Peter

    2014-03-01

    Brake squeal is still a major issue in the automotive industry due to comfort complaints of passengers and resulting high warranty costs. Many measures to avoid squeal have been discussed in the engineering community reaching from purely passive measures like the increase of damping, e.g. by the application of shims, to the active or semiactive suppression of squeal. While active measures can be effective but are elaborate and therefore more expensive, passive measure are less complex in most cases. This leads to the necessity to develop passive, economic and robust measures to avoid squeal. Asymmetry of the brake rotor has been proposed to achieve this goal and the resulting split of all double eigenfrequencies of the brake rotor has lately been shown to stabilize the system.

  9. Cool & Connected

    EPA Pesticide Factsheets

    The Cool & Connected planning assistance program helps communities develop strategies and an action plan for using broadband to promote environmentally and economically sustainable community development.

  10. Cooling wall

    SciTech Connect

    Nosenko, V.I.

    1995-07-01

    Protecting the shells of blast furnaces is being resolved by installing cast iron cooling plates. The cooling plates become non-operational in three to five years. The problem is that defects occur in manufacturing the cooling plates. With increased volume and intensity of work placed on blast furnaces, heat on the cast iron cooling plates reduces their reliability that limits the interim repair period of blast furnaces. Scientists and engineers from the Ukraine studied this problem for several years, developing a new method of cooling the blast furnace shaft called the cooling wall. Traditional cast iron plates were replaced by a screen of steel tubes, with the area between the tubes filled with fireproof concrete. Before placing the newly developed furnace shaft into operation, considerable work was completed such as theoretical calculations, design, research of temperature fields and tension. Continual testing over many years confirms the value of this research in operating blast furnaces. The cooling wall works with water cooling as well as vapor cooling and is operating in 14 blast furnaces in the Ukraine and two in Russia, and has operated for as long as 14 years.

  11. Cognition Is Cool: Can Hemispheric Activation Be Assessed by Tympanic Membrane Thermometry?

    ERIC Educational Resources Information Center

    Cherbuin, Nicolas; Brinkman, Cobie

    2004-01-01

    Hemispheric activation during cognitive tasks using functional magnetic resonance imaging (fMRI) can be difficult to interpret, uncomfortable, and is not widely available. This study investigated whether tympanic membrane thermometry could be used as a broad measure of hemispheric activation. Infrared probes measured ear temperature continuously…

  12. The ultra-lightweight support structure and gaseous helium cooling for the Mu3e silicon pixel tracker

    NASA Astrophysics Data System (ADS)

    Berger, N.; Herkert, A.; Huxold, L.; Schöning, A.; Wiedner, D.; Windelband, B.

    2014-08-01

    The Mu3e experiment searches for charged lepton flavor violation in the rare decay μ→eee. In order to reach a sensitivity of better than 10-16, more than 109 muon decays per second have to be observed over a running time of one year. Precise determination of particle momentum, vertex position and time are necessary for background suppression. These requirements can be met by combining an ultra-lightweight tracker based on High-Voltage Monolithic Active Pixel Sensors (HV-MAPS) with a timing system which consists of a scintillating fiber detector and a tile hodoscope. As the momentum of particles from muon decay at rest is below 53 MeV/c, the silicon pixel tracker resolution is dominated by multiple Coulomb scattering. This leads to extreme requirements for the material budget of the tracking detector of below 0.1% of a radiation length per layer. Even though the target power consumption of the HV-MAPS detector is as low as 150 mW/cm2, the detector cooling must be very efficient and at the same time avoid adding material inside the active tracking volume.

  13. Structure-Based Predictions of Activity Cliffs

    PubMed Central

    Husby, Jarmila; Bottegoni, Giovanni; Kufareva, Irina; Abagyan, Ruben; Cavalli, Andrea

    2015-01-01

    In drug discovery, it is generally accepted that neighboring molecules in a given descriptors' space display similar activities. However, even in regions that provide strong predictability, structurally similar molecules can occasionally display large differences in potency. In QSAR jargon, these discontinuities in the activity landscape are known as ‘activity cliffs’. In this study, we assessed the reliability of ligand docking and virtual ligand screening schemes in predicting activity cliffs. We performed our calculations on a diverse, independently collected database of cliff-forming co-crystals. Starting from ideal situations, which allowed us to establish our baseline, we progressively moved toward simulating more realistic scenarios. Ensemble- and template-docking achieved a significant level of accuracy, suggesting that, despite the well-known limitations of empirical scoring schemes, activity cliffs can be accurately predicted by advanced structure-based methods. PMID:25918827

  14. Cool Shelter

    ERIC Educational Resources Information Center

    Praeger, Charles E.

    2005-01-01

    Amid climbing energy costs and tightening budgets, administrators at school districts, colleges and universities are looking for all avenues of potential savings while promoting sustainable communities. Cool metal roofing can save schools money and promote sustainable design at the same time. Cool metal roofing keeps the sun's heat from collecting…

  15. Postexercise Cooling Rates in 2 Cooling Jackets

    PubMed Central

    Brade, Carly; Dawson, Brian; Wallman, Karen; Polglaze, Ted

    2010-01-01

    Abstract Context: Cooling jackets are a common method for removing stored heat accumulated during exercise. To date, the efficiency and practicality of different types of cooling jackets have received minimal investigation. Objective: To examine whether a cooling jacket containing a phase-change material (PC17) results in more rapid postexercise cooling than a gel cooling jacket and a no-jacket (control) condition. Design: Randomized, counterbalanced design with 3 experimental conditions. Setting: Participants exercised at 75% V̇o2max workload in a hot climate chamber (temperature  =  35.0 ± 1.4°C, relative humidity  =  52 ± 4%) for 30 minutes, followed by postexercise cooling for 30 minutes in cool laboratory conditions (ambient temperature  =  24.9 ± 1.8°C, relative humidity  =  39% ± 10%). Patients or Other Participants: Twelve physically active men (age  =  21.3 ± 1.1 years, height  =  182.7 ± 7.1 cm, body mass  =  76.2 ± 9.5 kg, sum of 6 skinfolds  =  50.5 ± 6.9 mm, body surface area  =  1.98 ± 0.14 m2, V̇o2max  =  49.0 ± 7.0 mL·kg−1·min−1) participated. Intervention(s): Three experimental conditions, consisting of a PC17 jacket, a gel jacket, and no jacket. Main Outcome Measure(s): Core temperature (TC), mean skin temperature (TSk), and TC cooling rate (°C/min). Results: Mean peak TC postexercise was 38.49 ± 0.42°C, 38.57 ± 0.41°C, and 38.55 ± 0.40°C for the PC17 jacket, gel jacket, and control conditions, respectively. No differences were observed in peak TC cooling rates among the PC17 jacket (0.038 ± 0.007°C/min), gel jacket (0.040 ± 0.009°C/min), and control (0.034 ± 0.010°C/min, P > .05) conditions. Between trials, no differences were calculated for mean TSk cooling. Conclusions: Similar cooling rates for all 3 conditions indicate that there is no benefit associated with wearing the PC17 or gel jacket. PMID:20210620

  16. Quinonaphthothiazines, syntheses, structures and anticancer activities

    NASA Astrophysics Data System (ADS)

    Jeleń, M.; Pluta, K.; Suwińska, K.; Morak-Młodawska, B.; Latocha, M.; Shkurenko, A.

    2015-11-01

    Two new types of pentacyclic azaphenothiazines being quinonaphthothiazines were obtaining from the reactions of dichlorodiquinolinyl disulfide with 1- and 2-naphthylamines. As the reactions could proceed in many ways, the proper structure elucidation was crucial. The structure determination was based on the 2D NMR spectra (NOESY, HSQC and HMBC) of the methyl derivatives. The final structure evidences came from X-ray analysis of the monocrystals. The new quinonaphthothiazines represent angularly fused pentacyclic ring systems which is folded along the N-S axis. The parent NH-compounds were transformed into the N-derivatives. Some quinonaphthothiazines exhibited promising anticancer activity against glioblastoma SNB-19, melanoma C-32 and human ductal breast epithelial tumor T47D cell lines. The anticancer activity dependent on the nature of the substituents and the ring fusion between the thiazine and naphthalene moieties. Two compounds were more active than the reference drug, cisplatin.

  17. Peptide Bacteriocins--Structure Activity Relationships.

    PubMed

    Etayash, Hashem; Azmi, Sarfuddin; Dangeti, Ramana; Kaur, Kamaljit

    2015-01-01

    With the growing concerns in the scientific and health communities over increasing levels of antibiotic resistance, antimicrobial peptide bacteriocins have emerged as promising alternatives to conventional small molecule antibiotics. A substantial attention has recently focused on the utilization of bacteriocins in food preservation and health safety. Despite the fact that a large number of bacteriocins have been reported, only a few have been fully characterized and structurally elucidated. Since knowledge of the molecular structure is a key for understanding the mechanism of action and therapeutic effects of peptide, we centered our focus in this review on the structure-activity relationships of bacteriocins with a particular focus in seven bacteriocins, namely, nisin, microcin J25, microcin B17, microcin C, leucocin A, sakacin P, and pediocin PA-1. Significant structural changes responsible for the altered activity of the recent bacteriocin analogues are discussed here.

  18. Effect of soaking, boiling, and steaming on total phenolic contentand antioxidant activities of cool season food legumes.

    PubMed

    Xu, Baojun; Chang, Sam K C

    2008-09-01

    The effects of soaking, boiling and steaming processes on the total phenolic components and antioxidant activity in commonly consumed cool season food legumes (CSFL's), including green pea, yellow pea, chickpea and lentil were investigated. As compared to original unprocessed legumes, all processing steps caused significant (p<0.05) decreases in total phenolic content (TPC), DPPH free radical scavenging activity (DPPH) in all tested CSFL's. All soaking and atmospheric boiling treatments caused significant (p<0.05) decreases in oxygen radical absorbing capacity (ORAC). However, pressure boiling and pressure steaming caused significant (p<0.05) increases in ORAC values. Steaming treatments resulted in a greater retention of TPC, DPPH, and ORAC values in all tested CSFL's as compared to boiling treatments. To obtain cooked legumes with similar palatability and firmness, pressure boiling shortened processing time as compared to atmospheric boiling, resulted in insignificant differences in TPC, DPPH for green and yellow pea. However, TPC and DPPH in cooked lentils differed significantly between atmospheric and pressure boiling. As compared to atmospheric processes, pressure processes significantly increased ORAC values in both boiled and steamed CSFL's. Greater TPC, DPPH and ORAC values were detected in boiling water than that in soaking and steaming water. Boiling also caused more solid loss than steaming. Steam processing exhibited several advantages in retaining the integrity of the legume appearance and texture of the cooked product, shortening process time, and greater retention of antioxidant components and activities.

  19. Terrestrial sensitivity to abrupt cooling recorded by aeolian activity in northwest Ohio, USA

    USGS Publications Warehouse

    Campbell, M.C.; Fisher, T.G.; Goble, R.J.

    2011-01-01

    Optically stimulated luminescence dated sand dunes and Pleistocene beach ridges in northwest Ohio are used to reconstruct landscape modification more than 5000. yr after deglaciation. Four of the OSL ages (13.3-11.1. ka) cluster around the Younger Dryas cold event, five ages (10.8-8.2. ka) cluster around the Preboreal, one young age (0.9-0.7. ka) records more recent aeolian activity, and one age of 15.1-13.1. ka dates a barrier spit in Lake Warren. In northwest Ohio, both landscape instability recorded by aeolian activity and a vegetation response recorded by pollen are coeval with the Younger Dryas. However, the climate conditions during the Preboreal resulting in aeolian activity are not recorded in the available pollen records. From this, we conclude that aeolian dunes and surfaces susceptible to deflation are sensitive to cooler, drier episodes of climate and can complement pollen data. Younger Dryas and Preboreal aged aeolian activity in northwestern Ohio coincides with aeolian records elsewhere in the Great Lakes region east of the prairie-forest ecotone. ?? 2011 University of Washington.

  20. The Cosmic History of Hot Gas Cooling and Radio AGN Activity in Massive Early-Type Galaxies

    NASA Technical Reports Server (NTRS)

    Danielson, A. L. R.; Lehmer, B. D.; Alexander, D. M.; Brandt, W. M.; Luo, B.; Miller, N.; Xue, Y. Q.; Stott, J. P.

    2012-01-01

    We study the X-ray properties of 393 optically selected early-type galaxies (ETGs) over the redshift range of z approx equals 0.0-1.2 in the Chandra Deep Fields. To measure the average X-ray properties of the ETG population, we use X-ray stacking analyses with a subset of 158 passive ETGs (148 of which were individually undetected in X-ray). This ETG subset was constructed to span the redshift ranges of z = 0.1-1.2 in the approx equals 4 Ms CDF-S and approx equals 2 Ms CDF-N and z = 0.1-0.6 in the approx equals 250 ks E-CDF-S where the contribution from individually undetected AGNs is expected to be negligible in our stacking. We find that 55 of the ETGs are detected individually in the X-rays, and 12 of these galaxies have properties consistent with being passive hot-gas dominated systems (i.e., systems not dominated by an X-ray bright Active Galactic Nucleus; AGN). On the basis of our analyses, we find little evolution in the mean 0.5-2 keY to B-band luminosity ratio (L(sub x) /L(sub Beta) varies as [1 +z]) since z approx equals 1.2, implying that some heating mechanism prevents the gas from cooling in these systems. We consider that feedback from radio-mode AGN activity could be responsible for heating the gas. We select radio AGNs in the ETG population using their far-infrared/radio flux ratio. Our radio observations allow us to constrain the duty cycle history of radio AGN activity in our ETG sample. We estimate that if scaling relations between radio and mechanical power hold out to z approx equals 1.2 for the ETG population being studied here, the average mechanical power from AGN activity is a factor of approx equals1.4 -- 2.6 times larger than the average radiative cooling power from hot gas over the redshift range z approx equals 0-1.2. The excess of inferred AGN mechanical power from these ETGs is consistent with that found in the local Universe for similar types of galaxies.

  1. Structure formation in sugar containing pectin gels - influence of tartaric acid content (pH) and cooling rate on the gelation of high-methoxylated pectin.

    PubMed

    Kastner, H; Kern, K; Wilde, R; Berthold, A; Einhorn-Stoll, U; Drusch, S

    2014-02-01

    The aim of the study was the application of a recently published method, using structuring parameters calculated from dG'/dt, for the characterisation of the pectin sugar acid gelation process. The influence of cooling rate and pH on structure formation of HM pectin gels containing 65 wt.% sucrose were investigated. The results show that the structure formation process as well as the properties of the final gels strongly depended on both parameters. With increasing cooling rates from 0.5 to 1.0 K/min the initial structuring temperature slightly decreased and the maximum structuring velocity increased. The lower the cooling rates, the firmer and more elastic were the final gels. With increasing acid content (decreasing pH from 2.5-2.0) the initial structuring temperatures were nearly constant. The final gel properties varied visibly but not systematically. Gels with the lowest and highest pH were less elastic and weaker compared to those with medium acid concentrations.

  2. Active Suppression Of Vibrations On Aircraft Structures

    NASA Technical Reports Server (NTRS)

    Maestrello, Lucio

    1995-01-01

    Method of active suppression of nonlinear and nonstationary vibrations developed to reduce sonic fatigue and interior noise in high-speed aircraft. Structure of aircraft exhibits periodic, chaotic, and random vibrations when forced by high-intensity sound from jet engines, shock waves, turbulence, and separated flows. Method of suppressing vibrations involves feedback control: Strain gauges or other sensors mounted in paths of propagation of vibrations on structure sense vibrations; outputs of sensors processed into control signal applied to actuator mounted on structure, inducing compensatory forces.

  3. Structural determinants of MALT1 protease activity.

    PubMed

    Wiesmann, Christian; Leder, Lukas; Blank, Jutta; Bernardi, Anna; Melkko, Samu; Decock, Arnaud; D'Arcy, Allan; Villard, Frederic; Erbel, Paulus; Hughes, Nicola; Freuler, Felix; Nikolay, Rainer; Alves, Juliano; Bornancin, Frederic; Renatus, Martin

    2012-05-25

    The formation of the CBM (CARD11-BCL10-MALT1) complex is pivotal for antigen-receptor-mediated activation of the transcription factor NF-κB. Signaling is dependent on MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1), which not only acts as a scaffolding protein but also possesses proteolytic activity mediated by its caspase-like domain. It remained unclear how the CBM activates MALT1. Here, we provide biochemical and structural evidence that MALT1 activation is dependent on its dimerization and show that mutations at the dimer interface abrogate activity in cells. The unliganded protease presents itself in a dimeric yet inactive state and undergoes substantial conformational changes upon substrate binding. These structural changes also affect the conformation of the C-terminal Ig-like domain, a domain that is required for MALT1 activity. Binding to the active site is coupled to a relative movement of caspase and Ig-like domains. MALT1 binding partners thus may have the potential of tuning MALT1 protease activity without binding directly to the caspase domain.

  4. Electron Cooling

    NASA Astrophysics Data System (ADS)

    Ellison, Timothy J. P.

    1991-08-01

    Electron cooling is a method of reducing the 6 -dimensional phase space volume of a stored ion beam. The technique was invented by Budker and first developed by him and his colleagues at the Institute for Nuclear Physics in Novosibirsk. Further studies of electron cooling were subsequently performed at CERN and Fermilab. At the Indiana University Cyclotron Facility (IUCF) an electron cooling system was designed, built, and commissioned in 1988. This was the highest energy system built to date (270 keV for cooling 500 MeV protons) and the first such system to be used as an instrument for performing nuclear and atomic physics experiments. This dissertation summarizes the design principles; measurements of the longitudinal drag rate (cooling force), equilibrium cooled beam properties and effective longitudinal electron beam temperature. These measurements are compared with theory and with the measured performance of other cooling systems. In addition the feasibility of extending this technology to energies an order of magnitude higher are discussed.

  5. Thermal/structural analyses of several hydrogen-cooled leading-edge concepts for hypersonic flight vehicles

    NASA Technical Reports Server (NTRS)

    Gladden, Herbert J.; Melis, Matthew E.; Mockler, Theodore T.; Tong, Mike

    1990-01-01

    The aerodynamic heating at high flight Mach numbers, when shock interference heating is included, can be extremely high and can exceed the capability of most conventional metallic and potential ceramic materials available. Numerical analyses of the heat transfer and thermal stresses are performed on three actively cooled leading-edge geometries (models) made of three different materials to address the issue of survivability in a hostile environment. These analyses show a mixture of results from one configuration to the next. Results for each configuration are presented and discussed. Combinations of enhanced internal film coefficients and high material thermal conductivity of copper and tungsten are predicted to maintain the maximum wall temperature for each concept within acceptable operating limits. The exception is the TD nickel material which is predicted to melt for most cases. The wide range of internal impingement film coefficients (based on correlations) for these conditions can lead to a significant uncertainty in expected leading-edge wall temperatures. The equivalent plastic strain, inherent in each configuration which results from the high thermal gradients, indicates a need for further cyclic analysis to determine component life.

  6. Definition and empirical structure of the range of stellar chromospheres-coronae across the H-R diagram: Cool stars

    NASA Technical Reports Server (NTRS)

    Linsky, J. L.

    1986-01-01

    Major advances in our understanding of non-radiative heating and other activity in stars cooler than T sub eff = 10,000K has occured in the last few years. This observational evidence is reviewed and the trends that are now becoming apparent are discussed. The evidence for non-radiatively heated outer atmospheric layers (chromospheres, transition regions, and coronae) in dwarf stars cooler than spectral type A7, in F and G giants, pre-main sequence stars, and close bindary systems is unambiguous, as is the evidence for chromospheres in the K and M giants and supergiants. The existence of non-radiative heating in the outer layers of the A stars remains undetermined despite repeated searches at all wavelengths. Two important trends in the data are the decrease in plasma emission measure with age on the main sequence and decreasing rotational velocity. Variability and atmospheric inhomogeneity are commonly seen, and there is considerable evidence that magnetic fields define the geometry and control the energy balance in the outer atmospheric layers. In addition, the microwave observations imply that non-thermal electrons are confined in coronal magnetic flux tubes in at least the cool dwarfs and RS CVn systems. The chromospheres in the K and M giants and supergiants are geometrically extended, as are the coronae in the RS CVn systems and probably also in other stars.

  7. Coronal temperatures of selected active cool stars as derived from low resolution Einstein observations

    NASA Technical Reports Server (NTRS)

    Vilhu, Osmi; Linsky, Jeffrey L.

    1990-01-01

    Mean coronal temperatures of some active G-K stars were derived from Rev1-processed Einstein-observatory's IPC-spectra. The combined X-ray and transition region emission line data are in rough agreement with static coronal loop models. Although the sample is too small to derive any statistically significant conclusions, it suggests that the mean coronal temperature depends linearly on the inverse Rossby-number, with saturation at short rotation periods.

  8. Aerothermal Performance of a Radiatively and Actively Cooled Panel at Mach 66

    DTIC Science & Technology

    1979-12-01

    Space Administration db~buuabU& Scie ~k ntUcn Tswh~ca Infamaltion Bran•h 1979 . .7 5 -, ’ WNW*" - --- sUrMMRY A flight-weight radiative and actively... ence 7. The panel holder has a sharp leading edge and a rectangular planform 141 cm (55.4 in.) wide by 300 cm (118 in.) long. The depth of the panel

  9. Structured Computer Learning Activities at School and Participation in Out-of-School Structured Activities.

    ERIC Educational Resources Information Center

    Hecht, Jeffrey B.; Dwyer, David J.

    1993-01-01

    Examines the relationship between student participation in structured activities and academic success at school; discusses the use of computers in schools; and describes a study that investigated 220 students in 3 high schools to determine relationships between participation in structured activities and successful computer use in school. (Contains…

  10. Cooled railplug

    DOEpatents

    Weldon, William F.

    1996-01-01

    The railplug is a plasma ignitor capable of injecting a high energy plasma jet into a combustion chamber of an internal combustion engine or continuous combustion system. An improved railplug is provided which has dual coaxial chambers (either internal or external to the center electrode) that provide for forced convective cooling of the electrodes using the normal pressure changes occurring in an internal combustion engine. This convective cooling reduces the temperature of the hot spot associated with the plasma initiation point, particularly in coaxial railplug configurations, and extends the useful life of the railplug. The convective cooling technique may also be employed in a railplug having parallel dual rails using dual, coaxial chambers.

  11. Hydrothermal activity in Tertiary Icelandic crust: Implication for cooling processes along slow-spreading mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Pałgan, D.; Devey, C. W.; Yeo, I. A.

    2015-12-01

    Known hydrothermal activity along the Mid-Atlantic Ridge is mostly high-temperature venting, controlled by volcano-tectonic processes confined to ridge axes and neotectonic zones ~15km wide on each side of the axis (e.g. TAG or Snake Pit). However, extensive exploration and discoveries of new hydrothermal fields in off-axis regions (e.g. Lost City, MAR) show that hydrothermalism may, in some areas, be dominated by off-axis venting. Little is known about nature of such systems, including whether low-temperature "diffuse" venting dominates rather than high-temperature black-smokers. This is particularly interesting since such systems may transport up to 90% of the hydrothermal heat to the oceans. In this study we use Icelandic hot springs as onshore analogues for off-shore hydrothermal activity along the MAR to better understand volcano-tectonic controls on their occurrence, along with processes supporting fluid circulation. Iceland is a unique laboratory to study how new oceanic crust cools and suggests that old crust may not be as inactive as previously thought. Our results show that Tertiary (>3.3 Myr) crust of Iceland (Westfjords) has widespread low-temperature hydrothermal activity. Lack of tectonism (indicated by lack of seismicity), along with field research suggest that faults in Westfjords are no longer active and that once sealed, can no longer support hydrothermal circulation, i.e. none of the hot springs in the area occur along faults. Instead, dyke margins provide open and permeable fluid migration pathways. Furthermore, we suggest that the Reykjanes Ridge (south of Iceland) may be similar to Westfjords with hydrothermalism dominated by off-axis venting. Using bathymetric data we infer dyke positions and suggest potential sites for future exploration located away from neotectonic zone. We also emphasise the importance of biological observations in seeking for low-temperature hydrothermal activity, since chemical or optical methods are not sufficient.

  12. Estrogenic flavonoids: structural requirements for biological activity.

    PubMed

    Miksicek, R J

    1995-01-01

    A systematic survey of polycyclic phenols has been performed to identify members of this chemical group with estrogenic activity. Twelve compounds were found to be able to stimulate the transcriptional activity of the human estrogen receptor expressed in cultured cells by transient transfection. These natural estrogens belong to several distinct, but chemically related classes including chalcones, flavanones, flavones, flavonols, and isoflavones. Selected examples of estrogenic flavonoids were further analyzed to determine their biological potencies and their relative affinities for binding to the estrogen receptor. These data are interpreted with respect to the molecular structure of polycyclic phenols required for hormonal activity as nonsteroidal estrogens.

  13. A shirt containing multistage phase change material and active cooling components was associated with increased exercise capacity in a hot, humid environment.

    PubMed

    McFarlin, Brian K; Henning, Andrea L; Venable, Adam S; Williams, Randall R; Best Sampson, Jill N

    2016-08-01

    Recent advances in clothing design include the incorporation of phase change materials (PCM) and other active cooling components (ACC) to provide better body heat dissipation. The purpose of this study was to determine the effect of wearing a shirt containing multistage PCM/ACC on exercise capacity at low (5.0), moderate-high (7.5) and extreme (9.0) levels of the physiological strain index (PSI). Fourteen individuals tested two shirts (control vs. cooling) during 45-min of interval running in a hot, humid (35 ± 1 °C; 55 ± 6% RH) environment. The cooling shirt resulted in an 8% improvement in exercise capacity at a PSI of 7.5 (p < 0.05). The observed increase in exercise capacity would likely translate to a significant improvement in exercise performance. More research is needed to determine a best practice approach for the use of cooling clothing as a counter to exercise-induced heat exposure. Practitioner Summary: In this report, we demonstrate that when forced to exercise in a hot, humid environment, an individual's exercise capacity may increase by as much as 8% when wearing a shirt composed of multistage phase change material and active cooling components.

  14. An Investigation of the Largest Flares in Active Cool Star Binaries with ALEXIS

    NASA Technical Reports Server (NTRS)

    Stern, Robert A.

    1998-01-01

    After a long delay due to the initial problems with the ALEXIS attitude control, the heroic efforts on the part of the ALEXIS satellite team enabled us to carry out this survey. However, the combination of the higher than expected and variable background in the ALEXIS detectors, and the lower throughput of the ALEXIS telescopes resulted in no convincing detections of large flares from the active binary systems. In addition, vignetting-corrected effective exposure times from the ALEXIS aspect solution were not available prior to the end of this contract; therefore, we were unable to convert upper limits measured in ALEXIS counts to the equivalent.

  15. Devitrification of Impact Glasses at the Bosumtwi Impact Structure, Ghana: Implications for Suevite Cooling History and Presence of Water

    NASA Astrophysics Data System (ADS)

    Välja, R.; Kirsimäe, K.; Koeberl, C.; Boamah, D. K.

    2015-09-01

    We report petrography and geochemistry of devitrification products in impact glasses in Bosumtwi suevites and we aim for refining the cooling history of suevites and estimate the presence-influence of water on the impact glass devitrification.

  16. An Active Broad Area Cooling Model of a Cryogenic Propellant Tank with a Single Stage Reverse Turbo-Brayton Cycle Cryocooler

    NASA Technical Reports Server (NTRS)

    Guzik, Monica C.; Tomsik, Thomas M.

    2011-01-01

    As focus shifts towards long-duration space exploration missions, an increased interest in active thermal control of cryogenic propellants to achieve zero boil-off of cryogens has emerged. An active thermal control concept of considerable merit is the integration of a broad area cooling system for a cryogenic propellant tank with a combined cryocooler and circulator system that can be used to reduce or even eliminate liquid cryogen boil-off. One prospective cryocooler and circulator combination is the reverse turbo-Brayton cycle cryocooler. This system is unique in that it has the ability to both cool and circulate the coolant gas efficiently in the same loop as the broad area cooling lines, allowing for a single cooling gas loop, with the primary heat rejection occurring by way of a radiator and/or aftercooler. Currently few modeling tools exist that can size and characterize an integrated reverse turbo-Brayton cycle cryocooler in combination with a broad area cooling design. This paper addresses efforts to create such a tool to assist in gaining a broader understanding of these systems, and investigate their performance in potential space missions. The model uses conventional engineering and thermodynamic relationships to predict the preliminary design parameters, including input power requirements, pressure drops, flow rate, cycle performance, cooling lift, broad area cooler line sizing, and component operating temperatures and pressures given the cooling load operating temperature, heat rejection temperature, compressor inlet pressure, compressor rotational speed, and cryogenic tank geometry. In addition, the model allows for the preliminary design analysis of the broad area cooling tubing, to determine the effect of tube sizing on the reverse turbo-Brayton cycle system performance. At the time this paper was written, the model was verified to match existing theoretical documentation within a reasonable margin. While further experimental data is needed for full

  17. Active structures to reduce torsional vibrations

    NASA Astrophysics Data System (ADS)

    Matthias, M.; Schlote, D.; Atzrodt, H.

    2013-03-01

    This paper describes the development of different active measures to reduce torsional vibrations in power trains. The measures are based on concepts developed for active mounts to reduce the transmission of structure-borne sound. To show the potential of these active measures and investigate their mode of operation to influence torsional vibrations, numerical simulations of powertrains with different active measures were done. First experimental results from tests on an experimental (reduced size) power train were used to align the numerical models. The work was done within the project 'LOEWE-Zentrum AdRIA: Adaptronik - Research, Innovation, Application' funded by the German federal state of Hessen, and the Project AKTos: 'Active control of torsional vibrations by coupling elements' placed in the research Framework program 'Navigation and Maritime Technology for the 21st Century' funded by the German Federal Ministry of Economics and Technology.

  18. Active vibration control of civil structures

    SciTech Connect

    Farrar, C.; Baker, W.; Fales, J.; Shevitz, D.

    1996-11-01

    This is a final report of a one year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Active vibration control (AVC) of structural and mechanical systems is one of the rapidly advancing areas of engineering research. The multifaceted nature of AVC covers many disciplines, such as sensors and instrumentation, numerical modeling, experimental mechanics, and advanced power systems. This work encompassed a review of the literature on active control of structures focusing both on active control hardware and on control algorithms, a design of an isolation systems using magneto-rheological fluid-filled (MRF) dampers and numerical simulations to study the enhanced vibration mitigation effects of this technology.

  19. Dynamics and Emergent Structures in Active Fluids

    NASA Astrophysics Data System (ADS)

    Baskaran, Aparna

    2014-03-01

    In this talk, we consider an active fluid of colloidal sized particles, with the primary manifestation of activity being a self-replenishing velocity along one body axis of the particle. This is a minimal model for varied systems such as bacterial colonies, cytoskeletal filament motility assays vibrated granular particles and self propelled diffusophoretic colloids, depending on the nature of interaction among the particles. Using microscopic Brownian dynamics simulations, coarse-graining using the tools of non-equilibrium statistical mechanics and analysis of macroscopic hydrodynamic theories, we characterize emergent structures seen in these systems, which are determined by the symmetry of the interactions among the active units, such as propagating density waves, dense stationary bands, asters and phase separated isotropic clusters. We identify a universal mechanism, termed ``self-regulation,'' as the underlying physics that leads to these structures in diverse systems. Support from NSF through DMR-1149266 and DMR-0820492.

  20. Apoptosome structure, assembly and procaspase activation

    PubMed Central

    Yuan, Shujun; Akey, Christopher W.

    2013-01-01

    Apaf-1 like molecules assemble into a ring-like platform known as the apoptosome. This cell death platform then activates procaspases in the intrinsic cell death pathway. In this review, crystal structures of Apaf-1 monomers and CED-4 dimers have been combined with apoptosome structures, to provide insights into the assembly of cell death platforms from humans, nematodes and flies. In humans, caspase recognition domains of procaspase-9 and Apaf-1 interact with each other to form a CARD-CARD disk, which interacts with the platform to create an asymmetric proteolysis machine. The disk tethers multiple pc-9 catalytic domains to the platform to raise their local concentration and this leads to zymogen activation. These advances have now set the stage for further studies of this critical activation process on the apoptosome. PMID:23561633

  1. Cool School.

    ERIC Educational Resources Information Center

    Stephens, Suzanne

    1980-01-01

    The design for Floyd Elementary School in Miami (Florida) seeks to harness solar energy to provide at least 70 percent of the annual energy for cooling needs and 90 percent for hot water. (Author/MLF)

  2. Cool Vest

    NASA Technical Reports Server (NTRS)

    1982-01-01

    ILC, Dover Division's lightweight cooling garment, called Cool Vest was designed to eliminate the harmful effects of heat stress; increases tolerance time in hot environments by almost 300 percent. Made of urethane-coated nylon used in Apollo, it works to keep the body cool, circulating chilled water throughout the lining by means of a small battery-powered pump. A pocket houses the pump, battery and the coolant which can be ice or a frozen gel, a valve control allows temperature regulation. One version is self-contained and portable for unrestrained movement, another has an umbilical line attached to an external source of coolant, such as standard tap water, when extended mobility is not required. It is reported from customers that the Cool Vest pays for itself in increased productivity in very high temperatures.

  3. Graphene-like structure of activated anthracites

    NASA Astrophysics Data System (ADS)

    Hawelek, L.; Woznica, N.; Brodka, A.; Fierro, V.; Celzard, A.; Bulou, A.; Burian, A.

    2012-12-01

    The structure of a series of activated carbons prepared from anthracite by chemical activation has been studied using wide-angle x-ray scattering, molecular dynamics and Raman spectroscopy. The BET surface areas of the investigated samples are in the range 1500-3430 m2 g-1 and the average pore sizes vary from 0.75 to 1.35 nm. The diffraction measurements were carried out to a maximum value of the scattering vector Kmax = 22 Å-1. The obtained diffraction data have been converted to a real space representation in the form of the pair correlation function. The structure of the studied samples consists of one or two graphite-like layers, stacked without spatial correlations. The size of the ordered layer region is approximately 24 Å. The atomic arrangement within an individual layer has been described in terms of paracrystalline ordering, in which lattice distortions are propagated proportionally to the square root of inter-atomic distances. The paracrystalline structure has been simulated by introducing the Stone-Thrower-Wales, mono-vacancy and di-vacancy defects, randomly distributed in the network. These defects lead to the formation of a defected network with the presence of non-hexagonal rings in which distortion of the structure extends outside of a defect region. Computer generated structural models have been relaxed at room temperature using the reactive empirical bond order potential for intra-layer interactions and the Lennard-Jones potential for inter-layer interactions. For such generated models the structure factors and the pair correlation functions were computed. A good agreement between the simulation results and the experimental data in both reciprocal and real space provides evidence for the correctness of the proposed models. The Raman data support the validity of these models. Porosity of the activated anthracites is discussed in relation to their defective structure.

  4. Program plan for reliability and maintainability in active solar heating and cooling systems

    NASA Astrophysics Data System (ADS)

    1980-10-01

    Specific objectives are as follows: provide all groups that have solar R & M concerns with the information that is available to the program and that can assist in alleviating those concerns; assist the solar energy industry in improving levels of R & M performance in state of the art solar energy systems, components, and materials; assist in the early development of a viable infrastructure for the design, manufacture, installation, and maintenance of reliable, maintainable, and durable solar energy systems; assist in the development of appropriate standards, code provisions, and certification programs relating to the R & M performance of solar energy systems, components, and materials; and develop the information required to support the other activities within the R & M program. These objectives correspond to five areas of action: regulations, research and development, technology transfer, solar industry infrastructure development, and data collection and analysis.

  5. Active vibration isolation using smart structures

    NASA Technical Reports Server (NTRS)

    Guigou, C.; Wagstaff, P. R.; Fuller, C. R.

    1991-01-01

    Passive technologies for the isolation of structures from vibrating sources are often inadequate. Using active control inputs applied directly to the source or designing a structure integrating the transducers required for the control inputs and the response measurements are ways of dealing with the problem. Results are given which were obtained on an experimental set up simulating this kind of problem where the form and the position of the transducers could be varied. By measuring the response of the structure integrated over a particular area the effects of particular types of modes could be taken into account to deal with specific types of input or limit particular modes of response more efficiently. Results of using different modes of vibration excitation of the receiving structure with and without control are presented for particular input frequencies. The problems of optimizing the control system to deal with multiple frequency inputs are discussed.

  6. Cool C4 Photosynthesis - Pyruvate Pi dikinase expression and activity corresponds to the exceptional cold tolerance of carbon assimilation in Miscanthus x giganteus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The biofuel feedstock grass Miscanthus x giganteus is exceptional among C4 species in its high productivity in cold climates. It can maintain photosynthetically active leaves at temperatures 6°C below the minimum for Zea mays (maize), which allows it a longer growing season in cool climates. Underst...

  7. Polychlorinated biphenyls as hormonally active structural analogues

    SciTech Connect

    McKinney, J.D. ); Waller, C.L. )

    1994-03-01

    Among the environmental chemicals that may be able to disrupt the endocrine systems of animals and humans, the polychlorinated biphenyls (PCBs) are a chemical class of considerable concern. One possible mechanism by which PCBs may interfere with endocrine function is their ability to mimic natural hormones. These actions reflect a close relationship between the physicochemical properties encoded in the PCB molecular structure and the responses they evoke in biological systems. These physiocochemical properties determine the molecular reactivities of PCBs and are responsible for their recognition as biological acceptors and receptors, as well as for triggering molecular mechanisms that lead to tissue response. [open quotes]Coplanarity[close quotes] of PCB phenyl rings and [open quotes]laterality[close quotes] of chlorine atoms are important structural features determining specific binding behavior with proteins and certain toxic responses in biological systems. We compare qualitative structure-activity relationships for PCBs with the limited information on the related non-coplanar chlorinated diphenyl ethers, providing further insights into the nature of the molecular recognition processes and support for the structural relationship of PCBs to thyroid hormones. Steriodlike activity requires conformational restriction and possibility hydroxylation. We offer some simple molecular recognition models to account for the importance of these different structural features in the structure-activity relationships that permit one to express PCB reactivities in terms of dioxin, thyroxine, and estradiol equivalents. The available data support the involvement of PCBs as mimics of thyroid and other steroidal hormones. The potential for reproductive and developmental toxicity associated with human exposure to PCBs is of particular concern. 53 refs., 6 figs.

  8. The influence of intrinsic sympathomimetic activity and beta-1 receptor selectivity on the recovery of finger skin temperature after finger cooling in normotensive subjects.

    PubMed

    Lenders, J W; Salemans, J; de Boo, T; Lemmens, W A; Thien, T; van't Laar, A

    1986-03-01

    A double-blind randomized study was designed to investigate differences in the recovery of finger skin temperature after finger cooling during dosing with placebo or one of four beta-blockers: propranolol, atenolol, pindolol, and acebutolol. In 11 normotensive nonsmoking subjects, finger skin temperature was measured with a thermocouple before and 20 minutes after immersion of one hand in a water bath at 16 degrees C. This finger cooling test caused no significant changes in systemic hemodynamics such as arterial blood pressure, heart rate, and forearm blood flow. The recovery of finger skin temperature during propranolol dosing was better than that during pindolol and atenolol dosing. There were no differences between the recoveries of skin temperature during pindolol, atenolol, and acebutolol dosing. Thus we could demonstrate no favorable effect of intrinsic sympathomimetic activity or beta 1-selectivity on the recovery of finger skin temperature after finger cooling.

  9. Calculation of vibrational branching ratios and hyperfine structure of 24Mg19F and its suitability for laser cooling and magneto-optical trapping

    NASA Astrophysics Data System (ADS)

    Xu, Liang; Yin, Yanning; Wei, Bin; Xia, Yong; Yin, Jianping

    2016-01-01

    More recently, laser cooling of the diatomic radical magnesium monofluoride (24Mg19F ) is being experimentally preformed [Appl. Phys. Express 8, 092701 (2015), 10.7567/APEX.8.092701 and Opt. Express 22, 28645 (2014), 10.1364/OE.22.028645] and was also studied theoretically [Phys. Rev. A 91, 042511 (2015), 10.1103/PhysRevA.91.042511]. However, some important problems still remain unsolved, so, in our paper, we perform further theoretical study for the feasibility of laser cooling and trapping the 24Mg19F molecule. At first, the highly diagonal Franck-Condon factors of the main transitions are verified by the closed-form approximation, Morse approximation, and Rydberg-Klein-Rees inversion methods, respectively. Afterwards, we investigate the lower X 2Σ1/2 + hyperfine manifolds using a quantum effective Hamiltonian approach and obtain the zero-field hyperfine spectrum with an accuracy of less than 30 kHz ˜5 μ K compared with the experimental results, and then find out that one cooling beam and one or two repumping beams with their first-order sidebands are enough to implement an efficient laser slowing and cooling of 24Mg19F . Meanwhile, we also calculate the accurate hyperfine structure magnetic g factors of the rotational state (X 2Σ1/2 +,N =1 ) and briefly discuss the influence of the external fields on the hyperfine structure of 24Mg19F as well as its possibility of preparing three-dimensional magneto-optical trapping. Finally we give an explanation for the difference between the Stark and Zeeman effects from the perspective of parity and time reversal symmetry. Our study shows that, besides appropriate excitation wavelengths, the short lifetime for the first excited state A 2Π1 /2 , and lighter mass, the 24Mg19F radical could be a good candidate molecule amenable to laser cooling and magneto-optical trapping.

  10. Cooling rate effects on the structure and transformation behavior of Cu-Zn-Al shape memory alloys

    NASA Astrophysics Data System (ADS)

    Lohan, Nicoleta-Monica; Suru, Marius-Gabriel; Pricop, Bogdan; Bujoreanu, Leandru-Gheorghe

    2014-11-01

    Different fragments of a hot-rolled and homogenized Cu-Zn-Al shape memory alloy (SMA) were subjected to thermal cycling by means of a differential scanning calorimetric (DSC) device. During thermal cycling, heating was performed at the same constant rate of increasing temperature while cooling was carried out at different rates of decreasing temperature. For each cooling rate, the temperature decreased in the same thermal interval. During each cooling stage, an exothermic peak (maximum) was observed on the DSC thermogram. This peak was associated with forward martensitic transformation. The DSC thermograms were analyzed with PROTEUS software: the critical martensitic transformation start (Ms) and finish (Mf) temperatures were determined by means of integral and tangent methods, and the dissipated heat was evaluated by the area between the corresponding maximum plot and a sigmoid baseline. The effects of the increase in cooling rate, assessed from a calorimetric viewpoint, consisted in the augmentation of the exothermic peak and the delay of direct martensitic transformation. The latter had the tendency to move to lower critical transformation temperatures. The martensite plates changed in morphology by becoming more oriented and by an augmenting in surface relief, which corresponded with the increase in cooling rate as observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM).

  11. Cooling-induced contraction of the rat gastric fundus: mediation via transient receptor potential (TRP) cation channel TRPM8 receptor and Rho-kinase activation.

    PubMed

    Mustafa, S; Oriowo, Ma

    2005-10-01

    1. Cooling has been shown to induce contractions of several smooth muscles in vitro. However, the mechanism involved in the response is not yet known. In the present study, we investigated the possible involvement of transient receptor potential (TRP) cation channel TRPM8 receptors and the Rho-kinase pathway in cooling-induced contraction of the rat fundus. 2. Cooling-induced contractions were inversely proportional to temperature. Contractions were significantly reduced (by 65.6 +/- 2.4%; P < 0.05) in a Ca2+-free (1 mmol/L EGTA) medium, but were not significantly inhibited by nifedipine (10(-6) mol/L). 3. Capsazepine (3 x 10(-6) and 3 x 10(-5) mol/L), a TRPM8 receptor antagonist, inhibited cooling-induced contraction of the rat gastric fundus. 4. The Rho-kinase inhibitor Y-27632 concentration-dependently inhibited cooling-induced contraction of the gastric fundus, producing approximately 90% inhibition at a concentration of 10(-5) mol/L. Contractions were also inhibited by genistein (3 x 10(-5) mol/L), a tyrosine kinase inhibitor, but not by GF 109203X (10(-7) mol/L), a protein kinase C inhibitor. 5. Using reverse transcription-polymerase chain reaction techniques, it was observed that the mRNA for the TRPM8 receptor and Rho-kinase were expressed in the rat gastric fundus. 6. These results would suggest that cooling-induced contraction of the rat fundus is mediated by activation of TRPM8 receptors via a mechanism involving activation of Rho-kinase.

  12. A high-resolution lake sediment record of glacier activity from SE Greenland defines abrupt Holocene cooling events

    NASA Astrophysics Data System (ADS)

    Balascio, N. L.; Bradley, R. S.; D'Andrea, W. J.

    2013-12-01

    Orbital driven changes in high latitude summer insolation during the Holocene are responsible for the primary millennial-scale climate trends in the Arctic. Following deglaciation, maximum summer temperatures generally occurred during the early to mid-Holocene and declined through the late Holocene. Superimposed on this gradual cooling trend are centennial- and decadal-scale intervals that indicate more rapid perturbations of the arctic climate system. Highly resolved sedimentary records from terrestrial and marine sites help to better characterize climate system dynamics during the Holocene and investigate forcing and feedback mechanism that operate on different timescales. Reconstructing glacial activity can provide valuable paleoclimate information about trends in summer temperature and/or winter precipitation. Proglacial lakes contain sediment archives of meltwater input from glaciers and typically have high sedimentation rates preserving detailed information on glacial activity. However, interpreting proglacial sedimentary records can be difficult because 1) there may be significant input of sediment from non-glacial sources, 2) there is often a lack of organic material for radiocarbon dating, and 3) not all glaciers are sensitive to rapid climatic changes. Here we present a c. 10 cal ka BP record of glacier activity from Kulusuk Lake (65.6°N, 37.1°W; 202 m a.s.l.), a proglacial lake in southeast Greenland that is well constrained by radiocarbon dates and shows a clear signal of changes in glacial input throughout the Holocene. Kulusuk Lake is presently fed by meltwater from two cirque glaciers. It has a small catchment and no other significant source of sediment input. A 3.5 m sediment core contains distinct lithologic changes defined by grain size, magnetic susceptibility, organic content, and scanning XRF data. During the early Holocene, an overall decrease in meltwater input from 8.7-7.7 ka indicates the retreat of the glaciers in response to regional

  13. Observation and interpretation of thermal instabilities at the front face of actively cooled limiters in TORE-SUPRA

    SciTech Connect

    Guilhem, D.; Hogan, J.T.; Mitteau, R.; Phillips, V.

    1995-12-01

    In TORE-SUPRA, actively cooled modular limiters (time constant = 2 s) covered with carbon have been used to exhaust the convective heat flux continuously up to 700 kW steady state (design value) without thermal instability, i.e., 4.5 MW/m{sup 2} on average. Steady state surface temperatures in the range 600 C (with 1.45 MW of Lower Hybrid waves) were routinely obtained. However, sudden surface temperature excursions from 600 C to 1,900 C, called ``super-brilliances``, were observed during ohmic or heated plasmas, taking place locally over 20 ms, which led to a new equilibrium. This new equilibrium correspond to a local increased power flux density to the limiter as confirmed by calorimetric measurements. Shot after shot, an increasing number of independent overheated zones (up to 4) were observed on the limiter ridge, the closest location to Last Closed Flux Surface (LCFS). The power extracted by the limiter then was {approximately} 1.1 MW (6.9 MW/m{sup 2} average and 15 MW/m{sup 2} maximum). Experimental data and possible mechanisms leading to a finite increased heat flux to the limiter surface are reviewed and comparisons with modelization are made.

  14. Betulin Phosphonates; Synthesis, Structure, and Cytotoxic Activity.

    PubMed

    Chrobak, Elwira; Bębenek, Ewa; Kadela-Tomanek, Monika; Latocha, Małgorzata; Jelsch, Christian; Wenger, Emmanuel; Boryczka, Stanisław

    2016-08-26

    Betulin derivatives are a widely studied group of compounds of natural origin due to their wide spectrum of biological activities. This paper describes new betulin derivatives, containing a phosphonate group. The allyl-vinyl isomerization and synthesis of acetylenic derivatives have been reported. Structural identification of products as E and Z isomers has been carried out using ¹H-, (13)C-, (31)P-NMR, and crystallographic analysis. The crystal structure in the orthorhombic space group and analysis of crystal packing contacts for 29-diethoxyphosphoryl-28-cyclopropylpropynoyloxy-lup-20E(29)-en-3β-ol 8a are reported. All new compounds were tested in vitro for their antiproliferative activity against human T47D (breast cancer), SNB-19 (glioblastoma), and C32 (melanoma) cell lines.

  15. Cooling rate correction and Detection of mineralogical evolution during Thellier-Thellier's experiments on baked clays. Applications to French protohistoric structures

    NASA Astrophysics Data System (ADS)

    Lanos, P.; Hervé, G.; Chauvin, A.; Perron d'Arc, M.

    2011-12-01

    Archaeointensity protocols have been considerably improved since the last years to better detect multidomain (MD) grains effects or mineralogical evolutions during Thellier's experiments. Current published data respect more strict criteria and take into account the anisotropy of thermoremanent magnetization (TRM). However the effect of the cooling rate on the intensity of the TRM acquired during cooling, which depends on the type of the ferromagnetic grains, remains difficult to precisely quantify. The main problem is to estimate the true cooling rate of the archeological structures and usually a 24 hours cooling is assumed. An experimental study of 35 small bricks baked in two kilns during summer 2007 and 2008 (in Sallèles d'Aude, southern France) gives new elements about the cooling rate correction. The used kilns are of two different sizes, similar to classical archaeological structures. Intensity of the geomagnetic field (43 μT) in the kilns and the temperature decrease during the cooling (around 12 hours for the small kiln and 70 hours for the other one) were measured. Discrepancies between the TRM intensity after fast (1.5 hour in the laboratory) and low cooling of 24 hours are over a very wide range between -5 and +30%. The use of the true cooling rate of the kilns (respectively 12 and 72 hours) gives mean archaeointensities (43.8±1.8 μT and 42.7±2.2 μT) corresponding to the intensity of the field measured within them. By applying the usual cooling of 24 hours, the intensity of the field is underestimated by 3 μT in the small kiln and is overestimated by 3 μT in the bigger kiln. Consequently, a wrong cooling rate correction may explain the dispersion between archaeointensities. The second aspect of the presentation corresponds to the detection of mineralogical evolution during successive heatings of the Thellier-Thellier's protocol. This problem is particularly important for the millennia BC in Europe, as very well heated structures are less common

  16. Molecular structure, chemical and nutrient profiles, and metabolic characteristics of the proteins and energy in new cool-season corn varieties harvested as fresh forage for dairy cattle.

    PubMed

    Abeysekara, Saman; Christensen, David A; Niu, Zhiyuan; Theodoridou, Katerina; Yu, Peiqiang

    2013-10-01

    To our knowledge, no previous research exists concerning the molecular structure and metabolic characteristics of the proteins and energy that new cool-season corn varieties provide for dairy cattle. The objectives of this study were to identify the differences in the molecular structures of proteins among several new cool-season corn varieties [Pioneer P7443R, Pioneer P7213R, Pioneer P7535R (Pioneer Hi-Bred International Inc., Johnston, IA), Hyland Baxxos RR, Hyland SR22, and Hyland SR06 (Hyland Seeds, Blenheim, ON, Canada)] using Fourier transform infrared attenuated total reflectance (FT/IR-ATR) molecular spectroscopy, and to determine the nutrient profile and supply that each variety provided for dairy cattle. The protein molecular structure studies showed that the amide I to amide II ratio ranged from 1.09 to 1.66 and that the α-helix to β-sheet ratio ranged from 0.95 to 1.01 among the new cool-season corn varieties. Energy content was significantly different among the new varieties. We found significant differences in the protein and carbohydrate subfractions and in the ruminal degradation kinetics of the organic matter, crude protein, starch, and neutral detergent fiber of the new varieties. The new varieties had similar estimated intestinal digestibilities for rumen undegraded crude protein. However, the new varieties had significant differences in predicted total truly absorbable protein, ranging from 39 to 57 g/kg of dry matter, indicating that these newly developed varieties are satisfactory sources of truly absorbed protein for dairy cattle. Further study on the molecular structure profiles of cool-season corn in relation to its nutrient utilization and availability in dairy cattle is necessary.

  17. Active Deformation in the Greater Himalayan Zone in Western Nepal from Inversion of New (U-Th)/He Cooling Ages

    NASA Astrophysics Data System (ADS)

    Harvey, J. E.; Burbank, D.

    2015-12-01

    Much of the central Himalaya features an abrupt rise in mean elevation from ~1.5 km in the Lesser Himalaya to ~4-5 km Greater Himalaya and Tibetan Plateau. This physiographic transition is known as PT2, and is often interpreted as the surface expression of transport over a ramp in the Main Himalayan Thrust (MHT). In western Nepal, however, the same rise in elevation occurs over two distinct topographic steps (PT2-N and PT2-S). In previous work, Harvey et al. (2015) argue that this anomalous topography is the result of recent southward-migration of mid-crustal deformation along the MHT. Due to the seismogenic potential of the MHT it is important to constrain its geometry in the western Nepal seismic gap, which has not had a large earthquake in over 600 years. To test the above hypothesis, we perform [U-Th]/He dating on 39 apatite and 47 zircon samples collected along seven relief transects throughout western Nepal. We constrain exhumation histories by inverting these new cooling ages with the 3-D thermo-kinematic model Pecube. Five transects collected from the Greater Himalaya north of PT2-N are best fit by relatively rapid exhumation rates (~1-2 km/Myr) since ~4 Ma. The other two, collected from farther south near PT2-S, require rapid (~1-2 km/Myr) exhumation until around 8-11 Ma, followed by much slower (~0.1-0.2 km/Myr) exhumation until at least the late Pliocene. Assuming that exhumation rates reflect uplift rates, the rapid Plio-Pleistocene exhumation in the Greater Himalaya north of PT2-N suggest that this physiographic transition is similar to that at the foot of the Greater Himalaya in central Nepal. It follows that active deformation is occurring along a NW-trend as much as 100 km farther north than would be expected if simply projecting PT2 across western Nepal. This finding is consistent with transport over a more northerly MHT ramp or perhaps oblique slip along the recently identified, surface-breaking WNFZ. Although the geomorphology and microseismicity

  18. Regeneratively Cooled Porous Media Jacket

    NASA Technical Reports Server (NTRS)

    Mungas, Greg (Inventor); Fisher, David J. (Inventor); London, Adam Pollok (Inventor); Fryer, Jack Merrill (Inventor)

    2013-01-01

    The fluid and heat transfer theory for regenerative cooling of a rocket combustion chamber with a porous media coolant jacket is presented. This model is used to design a regeneratively cooled rocket or other high temperature engine cooling jacket. Cooling jackets comprising impermeable inner and outer walls, and porous media channels are disclosed. Also disclosed are porous media coolant jackets with additional structures designed to transfer heat directly from the inner wall to the outer wall, and structures designed to direct movement of the coolant fluid from the inner wall to the outer wall. Methods of making such jackets are also disclosed.

  19. Investigation of structural defects in In-doped CdZnTe under different in-situ annealing cooling rates

    NASA Astrophysics Data System (ADS)

    Xing, Xiaobing; Min, Jiahua; Liang, Xiaoyan; Zhang, Jijun; Wang, Linjun; Yang, Liuqing; Ling, Yunpeng; Duan, Lei; Shen, Yue

    2015-09-01

    The In-doped Cd0.9Zn0.1Te (CZT) crystals were grown by the modified Vertical Bridgeman method and treated by in-situ annealing with six different cooling rates. Photo-Induced Transient Spectroscopy (PICTS) and IR microscopy were employed to investigate the evolution mechanism of point defects and bulk defects (mainly Te inclusions) in the CZT crystals with different cooling rates. Related optical and electrical properties were investigated by Fourier Transform Infrared Spectrometer (FTIR) and I-V measurements. The results indicated that cooling at slow rate (10-20 K/h) could decrease the concentration of point defects, such as A center, Cd vacancy (VCd2-), Te antisite (TeCd2+) and so on, while the Te inclusions are of larger dimension and lower concentration. Otherwise, the faster cooling rate (50-60 K/h), the higher concentration of these point defects, and Te inclusion present small size but much larger concentration. Moreover, cooling too fast or too slow significantly degrades the optical and electrical properties. When cooled at 30-40 K/h, the concentration of internal point defects is the lowest, suggesting that VCd2- compensated with TeCd2+ to reach a new equilibrium corresponding to the theory of quasichemical defect reactions (QCDR). In addition, a certain concentration of TeCd2+ was beneficial to pin the Fermi-level, and the Te inclusions presented lowest total volume fraction, which made the crystals perform great with higher resistivity and infrared transmittance.

  20. Cooled railplug

    DOEpatents

    Weldon, W.F.

    1996-05-07

    The railplug is a plasma ignitor capable of injecting a high energy plasma jet into a combustion chamber of an internal combustion engine or continuous combustion system. An improved railplug is provided which has dual coaxial chambers (either internal or external to the center electrode) that provide for forced convective cooling of the electrodes using the normal pressure changes occurring in an internal combustion engine. This convective cooling reduces the temperature of the hot spot associated with the plasma initiation point, particularly in coaxial railplug configurations, and extends the useful life of the railplug. The convective cooling technique may also be employed in a railplug having parallel dual rails using dual, coaxial chambers. 10 figs.

  1. Dynamic structure of active nematic shells

    PubMed Central

    Zhang, Rui; Zhou, Ye; Rahimi, Mohammad; de Pablo, Juan J.

    2016-01-01

    When a thin film of active, nematic microtubules and kinesin motor clusters is confined on the surface of a vesicle, four +1/2 topological defects oscillate in a periodic manner between tetrahedral and planar arrangements. Here a theoretical description of nematics, coupled to the relevant hydrodynamic equations, is presented here to explain the dynamics of active nematic shells. In extensile microtubule systems, the defects repel each other due to elasticity, and their collective motion leads to closed trajectories along the edges of a cube. That motion is accompanied by oscillations of their velocities, and the emergence and annihilation of vortices. When the activity increases, the system enters a chaotic regime. In contrast, for contractile systems, which are representative of some bacterial suspensions, a hitherto unknown static structure is predicted, where pairs of defects attract each other and flows arise spontaneously. PMID:27869130

  2. Dynamic structure of active nematic shells

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Zhou, Ye; Rahimi, Mohammad; de Pablo, Juan J.

    2016-11-01

    When a thin film of active, nematic microtubules and kinesin motor clusters is confined on the surface of a vesicle, four +1/2 topological defects oscillate in a periodic manner between tetrahedral and planar arrangements. Here a theoretical description of nematics, coupled to the relevant hydrodynamic equations, is presented here to explain the dynamics of active nematic shells. In extensile microtubule systems, the defects repel each other due to elasticity, and their collective motion leads to closed trajectories along the edges of a cube. That motion is accompanied by oscillations of their velocities, and the emergence and annihilation of vortices. When the activity increases, the system enters a chaotic regime. In contrast, for contractile systems, which are representative of some bacterial suspensions, a hitherto unknown static structure is predicted, where pairs of defects attract each other and flows arise spontaneously.

  3. Patterns of fish assemblage structure and dynamics in waters of the Savannah River Plant. Comprehensive Cooling Water Study final report

    SciTech Connect

    Aho, J.M.; Anderson, C.S.; Floyd, K.B.; Negus, M.T.; Meador, M.R.

    1986-06-01

    Research conducted as part of the Comprehensive Cooling Water Study (CCWS) has elucidated many factors that are important to fish population and community dynamics in a variety of habitats on the Savannah River Plant (SRP). Information gained from these studies is useful in predicting fish responses to SRP operations. The overall objective of the CCWS was (1) to determine the environmental effects of SRP cooling water withdrawals and discharges and (2) to determine the significance of the cooling water impacts on the environment. The purpose of this study was to: (1) examine the effects of thermal plumes on anadromous and resident fishes, including overwintering effects, in the SRP swamp and associated tributary streams; (2) assess fish spawning and locate nursery grounds on the SRP; (3) examine the level of use of the SRP by spawning fish from the Savannah River, this objective was shared with the Savannah River Laboratory, E.I. du Pont de Nemours and Company; and (4) determine impacts of cooling-water discharges on fish population and community attributes. Five studies were designed to address the above topics. The specific objectives and a summary of the findings of each study are presented.

  4. Ceramide structure predicts tumor ganglioside immunosuppressive activity.

    PubMed Central

    Ladisch, S; Li, R; Olson, E

    1994-01-01

    Molecular determinants of biological activity of gangliosides are generally believed to be carbohydrate in nature. However, our studies of immunomodulation by highly purified naturally occurring tumor gangliosides provide another perspective: while the immunosuppressive activity of gangliosides requires the intact molecule (both carbohydrate and ceramide moieties), ceramide structure strikingly influences ganglioside immunosuppressive activity. Molecular species of human neuroblastoma GD2 ganglioside in which the ceramide contains a shorter fatty acyl chain (C16:0, C18:0) were 6- to 10-fold more active than those with a longer fatty acyl chain (C22:0/C24:1, C24:0). These findings were confirmed in studies of ceramide species of human leukemia sialosylparagloboside and murine lymphoma GalNAcGM1b. Gangliosides that contain shorter-chain fatty acids (and are most immunosuppressive) are known to be preferentially shed by tumor cells. Therefore, the results suggest that the tumor cell is optimized to protect itself from host immune destruction by selective shedding of highly active ceramide species of gangliosides. Images PMID:8127917

  5. Cooling rate and thermal structure determined from progressive magnetization of the dacite dome at Mount St. Helens, Washington

    SciTech Connect

    Dzurisin, D. ); Denlinger, R.P. ); Rosenbaum, J.G. )

    1990-03-10

    The study suggests that the dome consists of a hot, nonmagnetized core surrounded by a cool magnetized carapace and flanking talus. Temporal changes in the magnetic anomaly indicate that the magnetized carapace thickened at an average rate of 0.03 {plus minus} 0.01 m/d from 1984 to 1986. Petrographic and rock magnetic properties of dome samples indicate that the dominant process responsible for these changes is magnetization of extensively oxidized rock at progressively deeper levels within the dome as the rock cools through its blocking temperature, rather than subsequent changes in magetization caused by further oxidation. Newly extruded material cools rapidly for a short period as heat is conducted outward in response to convective heat loss from its surface. The cooling rate gradually declines for several weeks, and thereafter the material cools at a relatively constant rate by convective heat loss from its interior along fractures that propagate inward. The rate of internal convective heat loss through fractures varies with rainfall, snowmelt, and large-scale fracturing during subsequent eruptive episodes. In accordance with a model for solidification of the 1959 lava lake at Kilauea Iki, Hawaii, the authors picture the dome's magnetized carapace as being a two-phase, porous, convective zone separated from the nonmagnetized core of the dome by a thin, single-phase conductive zone. As a consequence of the heat balance between the conductive and convective zones, the blocking-temperature isotherm migrates inward at a relatively constant rate. If the dome remains inactive, the time scale for its complete magnetization is estimated to be 18-36 years, a forecast which can be refined by shallow drilling into the dome and by continuing studies of its growing magnetic anomaly.

  6. Cooling vest

    NASA Technical Reports Server (NTRS)

    Kosmo, J.; Kane, J.; Coverdale, J.

    1977-01-01

    Inexpensive vest of heat-sealable urethane material, when strapped to person's body, presents significant uncomplicated cooling system for environments where heavy accumulation of metabolic heat exists. Garment is applicable to occupations where physical exertion is required under heavy protective clothing.

  7. BK channel activation: structural and functional insights

    PubMed Central

    Lee, Urvi S.; Cui, Jianmin

    2010-01-01

    The voltage and Ca2+ activated K+ (BK) channels are involved in the regulation of neurotransmitter release and neuronal excitability. Structurally, BK channels are homologous to voltage- and ligand-gated K+ channels, having a voltage sensor and pore as the membrane-spanning domain and a cytosolic domain containing metal binding sites. Recently published electron cryomicroscopy (cryo-EM) and X-ray crystallographic structures of the BK channel provided the first look into the assembly of these domains, corroborating the close interactions among these domains during channel gating that have been suggested by functional studies. This review discusses these latest findings and an emerging new understanding about BK channel gating and implications for diseases such as epilepsy, in which mutations in BK channel genes have been associated. PMID:20663573

  8. Black holes, cooling flows and galaxy formation.

    PubMed

    Peacock, J A

    2005-03-15

    Central black holes in galaxies are now well established as a ubiquitous phenomenon, and this fact is important for theories of cosmological structure formation. Merging of galaxy haloes must preserve the proportionality between black hole mass and baryonic mass; the way in which this happens may help solve difficulties with existing ing models of galaxy formation, which suffer from excessive cooling and thus over- produce stars. Feedback from active nuclei may be the missing piece of the puzzle, regulating galaxy-scale cooling flows. Such a process now seems to be observed in cluster-scale cooling flows, where dissipation of sound waves generated by radio lobes can plausibly balance the energy lost in X-rays, at least in a time-averaged sense.

  9. Radiative cooling for thermophotovoltaic systems

    NASA Astrophysics Data System (ADS)

    Zhou, Zhiguang; Sun, Xingshu; Bermel, Peter

    2016-09-01

    Radiative cooling has recently garnered a great deal of attention for its potential as an alternative method for photovoltaic thermal management. Here, we will consider the limits of radiative cooling for thermal management of electronics broadly, as well as a specific application to thermal power generation. We show that radiative cooling power can increase rapidly with temperature, and is particularly beneficial in systems lacking standard convective cooling. This finding indicates that systems previously operating at elevated temperatures (e.g., 80°C) can be passively cooled close to ambient under appropriate conditions with a reasonable cooling area. To examine these general principles for a previously unexplored application, we consider the problem of thermophotovoltaic (TPV) conversion of heat to electricity via thermal radiation illuminating a photovoltaic diode. Since TPV systems generally operate in vacuum, convective cooling is sharply limited, but radiative cooling can be implemented with proper choice of materials and structures. In this work, realistic simulations of system performance are performed using the rigorous coupled wave analysis (RCWA) techniques to capture thermal emitter radiation, PV diode absorption, and radiative cooling. We subsequently optimize the structural geometry within realistic design constraints to find the best configurations to minimize operating temperature. It is found that low-iron soda-lime glass can potentially cool the PV diode by a substantial amount, even to below ambient temperatures. The cooling effect can be further improved by adding 2D-periodic photonic crystal structures. We find that the improvement of efficiency can be as much as an 18% relative increase, relative to the non-radiatively cooled baseline, as well as a potentially significant improvement in PV diode lifetime.

  10. Warm and Cool Cityscapes

    ERIC Educational Resources Information Center

    Jubelirer, Shelly

    2012-01-01

    Painting cityscapes is a great way to teach first-grade students about warm and cool colors. Before the painting begins, the author and her class have an in-depth discussion about big cities and what types of buildings or structures that might be seen in them. They talk about large apartment and condo buildings, skyscrapers, art museums,…

  11. System identification and control of the JPL active structure

    NASA Technical Reports Server (NTRS)

    Fanson, J. L.; Lurie, B. J.; O'Brien, J. F.; Chu, C.-C.; Smith, R. S.

    1991-01-01

    This paper describes recent advances in structural quieting technology as applied to active truss structures intended for high precision space based optics applications. Collocated active damping control loops are designed in order to impedance match piezoelectric active members to the structure. Noncollocated control loops are also studied in relation to controlling lightly damped structures.

  12. Methods of beam cooling

    SciTech Connect

    Sessler, A.M.

    1996-02-01

    Diverse methods which are available for particle beam cooling are reviewed. They consist of some highly developed techniques such as radiation damping, electron cooling, stochastic cooling and the more recently developed, laser cooling. Methods which have been theoretically developed, but not yet achieved experimentally, are also reviewed. They consist of ionization cooling, laser cooling in three dimensions and stimulated radiation cooling.

  13. Hierarchically structured activated carbon for ultracapacitors

    PubMed Central

    Kim, Mok-Hwa; Kim, Kwang-Bum; Park, Sun-Min; Roh, Kwang Chul

    2016-01-01

    To resolve the pore-associated bottleneck problem observed in the electrode materials used for ultracapacitors, which inhibits the transport of the electrolyte ions, we designed hierarchically structured activated carbon (HAC) by synthesizing a mesoporous silica template/carbon composite and chemically activating it to simultaneously remove the silica template and increase the pore volume. The resulting HAC had a well-designed, unique porous structure, which allowed for large interfaces for efficient electric double-layer formation. Given the unique characteristics of the HAC, we believe that the developed synthesis strategy provides important insights into the design and fabrication of hierarchical carbon nanostructures. The HAC, which had a specific surface area of 1,957 m2 g−1, exhibited an extremely high specific capacitance of 157 F g−1 (95 F cc−1), as well as a high rate capability. This indicated that it had superior energy storage capability and was thus suitable for use in advanced ultracapacitors. PMID:26878820

  14. Kinetic model for predicting the concentrations of active halogens species in chlorinated saline cooling waters. Final report

    SciTech Connect

    Haag, W.R.; Lietzke, M.H.

    1981-08-01

    A kinetic model has been developed for describing the speciation of chlorine-produced oxidants in seawater as a function of time. The model is applicable under a broad variety of conditions, including all pH range, salinities, temperatures, ammonia concentrations, organic amine concentrations, and chlorine doses likely to be encountered during power plant cooling water chlorination. However, the effects of sunlight are not considered. The model can also be applied to freshwater and recirculating water systems with cooling towers. The results of the model agree with expectation, however, complete verification is not feasible at the present because analytical methods for some of the predicted species are lacking.

  15. Structure -activity relationships of PDE5 inhibitors.

    PubMed

    Eros, D; Szántai-Kis, Cs; Kiss, R; Kéri, Gy; Hegymegi-Barakonyi, B; Kövesdi, I; Orfi, L

    2008-01-01

    cGMP has a short-term effect on smooth muscle tone and a longer-term effect on responses to chronic drug treatment or proliferative signals. cGMP-Phosphodiesterase type 5 (PDE5) hydrolizes cGMP, and the result is smooth muscle contraction. PDE5 is a relatively novel therapeutic target of various diseases, such as erectile dysfunction and pulmonary hypertension. The most intensively examined and marketed PDE5 inhibitor was sildenafil (Viagra) but recently vardenafil (Levitra) and tadalafil (Cialis) were launched with beneficial ADME parameters and PDE5 selectivity. The increasing interest in PDE5 inhibition made it reasonable to collect the available inhibitory data from the scientific literature and set up a structure-activity relationship study. Chemical structures of 438 compounds and their cGMP-PDE5 inhibitory data (IC50) were collected from recently published articles. In this paper physiology, regulation and inhibition of PDE5 (and briefly other PDE-s) are discussed and inhibitors are tabulated by the core structures. Finally, a general QSAR model built from these data is presented. All data used in the QSAR study were summarized in a Supplement (for description please see the online version of the article).

  16. Energy storage using phase-change materials for active solar heating and cooling: An evaluation of future research and development direction

    NASA Astrophysics Data System (ADS)

    Borkowski, R. J.; Stovall, T. K.; Kedl, R. J.; Tomlinson, J. J.

    1982-04-01

    The current state of the art and commercial potential of active solar heating and cooling systems for buildings, and the use of thermal energy storage with these systems are assessed. The need for advanced latent heat storage subsystems in these applications and priorities for their development are determined. Latent storage subsystems are advantageous in applications where their compactness may be exploited. It is suggested that subsystems could facilitate storage in retrofit applications in which storage would be physically impossible otherwise.

  17. Updating of ASME Nuclear Code Case N-201 to Accommodate the Needs of Metallic Core Support Structures for High Temperature Gas Cooled Reactors Currently in Development

    SciTech Connect

    Mit Basol; John F. Kielb; John F. MuHooly; Kobus Smit

    2007-05-02

    On September 29, 2005, ASME Standards Technology, LLC (ASME ST-LLC) executed a multi-year, cooperative agreement with the United States DOE for the Generation IV Reactor Materials project. The project's objective is to update and expand appropriate materials, construction, and design codes for application in future Generation IV nuclear reactor systems that operate at elevated temperatures. Task 4 was embarked upon in recognition of the large quantity of ongoing reactor designs utilizing high temperature technology. Since Code Case N-201 had not seen a significant revision (except for a minor revision in September, 2006 to change the SA-336 forging reference for 304SS and 316SS to SA-965 in Tables 1.2(a) and 1.2(b), and some minor editorial changes) since December 1994, identifying recommended updates to support the current high temperature Core Support Structure (CSS) designs and potential new designs was important. As anticipated, the Task 4 effort identified a number of Code Case N-201 issues. Items requiring further consideration range from addressing apparent inconsistencies in definitions and certain material properties between CC-N-201 and Subsection NH, to inclusion of additional materials to provide the designer more flexibility of design. Task 4 developed a design parameter survey that requested input from the CSS designers of ongoing high temperature gas cooled reactor metallic core support designs. The responses to the survey provided Task 4 valuable input to identify the design operating parameters and future needs of the CSS designers. Types of materials, metal temperature, time of exposure, design pressure, design life, and fluence levels were included in the Task 4 survey responses. The results of the survey are included in this report. This research proves that additional work must be done to update Code Case N-201. Task 4 activities provide the framework for the Code Case N-201 update and future work to provide input on materials. Candidate

  18. Provisioning cooling elements for chillerless data centers

    DOEpatents

    Chainer, Timothy J.; Parida, Pritish R.

    2016-12-13

    Systems and methods for cooling include one or more computing structure, an inter-structure liquid cooling system that includes valves configured to selectively provide liquid coolant to the one or more computing structures; a heat rejection system that includes one or more heat rejection units configured to cool liquid coolant; and one or more liquid-to-liquid heat exchangers that include valves configured to selectively transfer heat from liquid coolant in the inter-structure liquid cooling system to liquid coolant in the heat rejection system. Each computing structure further includes one or more liquid-cooled servers; and an intra-structure liquid cooling system that has valves configured to selectively provide liquid coolant to the one or more liquid-cooled servers.

  19. Improvement of heat pipe performance through integration of a coral biomaterial wick structure into the heat pipe of a CPU cooling system

    NASA Astrophysics Data System (ADS)

    Putra, Nandy; Septiadi, Wayan Nata

    2016-08-01

    The very high heat flux dissipated by a Central Processing Unit (CPU) can no longer be handled by a conventional, single-phased cooling system. Thermal management of a CPU is now moving towards two-phase systems to maintain CPUs below their maximum temperature. A heat pipe is one of the emerging cooling systems to address this issue because of its superior efficiency and energy input independence. The goal of this research is to improve the performance of a heat pipe by integrating a biomaterial as the wick structure. In this work, the heat pipe was made from copper pipe and the biomaterial wick structure was made from tabulate coral with a mean pore diameter of 52.95 μm. For comparison purposes, the wick structure was fabricated from sintered Cu-powder with a mean pore diameter of 58.57 µm. The working fluid for this experiment was water. The experiment was conducted using a processor as the heat source and a plate simulator to measure the heat flux. The utilization of coral as the wick structure can improve the performance of a heat pipe and can decrease the temperature of a simulator plate by as much as 38.6 % at the maximum heat load compared to a conventional copper heat sink. This method also decreased the temperature of the simulator plate by as much as 44.25 °C compared to a heat pipe composed of a sintered Cu-powder wick.

  20. I-Xe structure of ILAFEGH 009 and shallowater: Evidence for early formation and rapid cooling of impact-derived enstatite meteorites

    NASA Technical Reports Server (NTRS)

    Kehm, K.; Nichols, R. H., Jr.; Hohenberg, C. M.; Mccoy, T. J.; Keil, K.

    1993-01-01

    Enstatite meteorites have proven to be ideal samples for past studies of the I-Xe system. This work focuses on two enstatite meteorites that were formed by impact processes. Ilafegh 009 is a clast-free impact melt rock from the EL chondrite parent body. The Shallowater aubrite likely formed when a fully molten planetesimal collided with a solid planetesimal, mixing fragments of the solid planetesimal into the enstatite mantle of the molten planetesimal. A complex three-stage cooling history resulted from this mixing and later break-up and reassembly of the parent body. The present study indicates that the I-Xe structure of these two meteorites resulted from in situ decay of live I-129 and that both experienced xenon closure of the iodine host phase at approximately the same time. I-Xe cooling rates are consistent with the cooling rates derived from mineralogic and petrologic studies of these objects. The similarities in ages suggest that the region of the nebula in which enstatite parent bodies formed must have experienced an intense early bombardment.

  1. Neutron Damage in Mechanically-Cooled High-Purity Germanium Detectors for Field-Portable Prompt Gamma Neutron Activation Analysis (PGNAA) Systems

    SciTech Connect

    E.H. Seabury; C.J. Wharton; A.J. Caffrey; J.B. McCabe; C. DeW. Van Siclen

    2013-10-01

    Prompt Gamma Neutron Activation (PGNAA) systems require the use of a gamma-ray spectrometer to record the gamma-ray spectrum of an object under test and allow the determination of the object’s composition. Field-portable systems, such as Idaho National Laboratory’s PINS system, have used standard liquid-nitrogen-cooled high-purity germanium (HPGe) detectors to perform this function. These detectors have performed very well in the past, but the requirement of liquid-nitrogen cooling limits their use to areas where liquid nitrogen is readily available or produced on-site. Also, having a relatively large volume of liquid nitrogen close to the detector can impact some assessments, possibly leading to a false detection of explosives or other nitrogen-containing chemical. Use of a mechanically-cooled HPGe detector is therefore very attractive for PGNAA applications where nitrogen detection is critical or where liquid-nitrogen logistics are problematic. Mechanically-cooled HPGe detectors constructed from p-type germanium, such as Ortec’s trans-SPEC, have been commercially available for several years. In order to assess whether these detectors would be suitable for use in a fielded PGNAA system, Idaho National Laboratory (INL) has been performing a number of tests of the resistance of mechanically-cooled HPGe detectors to neutron damage. These detectors have been standard commercially-available p-type HPGe detectors as well as prototype n-type HPGe detectors. These tests compare the performance of these different detector types as a function of crystal temperature and incident neutron fluence on the crystal.

  2. Berkeley Lab's Cool Your School Program

    ScienceCinema

    Ivan Berry

    2016-07-12

    Cool Your School is a series of 6th-grade, classroom-based, science activities rooted in Berkeley Lab's cool-surface and cool materials research and aligned with California science content standards. The activities are designed to build knowledge, stimulate curiosity, and carry the conversation about human-induced climate change, and what can be done about it, into the community.

  3. Berkeley Lab's Cool Your School Program

    SciTech Connect

    Ivan Berry

    2012-07-30

    Cool Your School is a series of 6th-grade, classroom-based, science activities rooted in Berkeley Lab's cool-surface and cool materials research and aligned with California science content standards. The activities are designed to build knowledge, stimulate curiosity, and carry the conversation about human-induced climate change, and what can be done about it, into the community.

  4. Electronic cooling using thermoelectric devices

    SciTech Connect

    Zebarjadi, M.

    2015-05-18

    Thermoelectric coolers or Peltier coolers are used to pump heat in the opposite direction of the natural heat flux. These coolers have also been proposed for electronic cooling, wherein the aim is to pump heat in the natural heat flux direction and from hot spots to the colder ambient temperature. In this manuscript, we show that for such applications, one needs to use thermoelectric materials with large thermal conductivity and large power factor, instead of the traditionally used high ZT thermoelectric materials. We further show that with the known thermoelectric materials, the active cooling cannot compete with passive cooling, and one needs to explore a new set of materials to provide a cooling solution better than a regular copper heat sink. We propose a set of materials and directions for exploring possible materials candidates suitable for electronic cooling. Finally, to achieve maximum cooling, we propose to use thermoelectric elements as fins attached to copper blocks.

  5. The Structure of Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Kriss, Gerard A.

    1997-01-01

    We are continuing our systematic investigation of the nuclear structure of nearby active galactic nuclei (AGN). Upon completion, our study will characterize hypothetical constructs such as narrow-line clouds, obscuring tori, nuclear gas disks. and central black holes with physical measurements for a complete sample of nearby AGN. The major scientific goals of our program are: (1) the morphology of the NLR; (2) the physical conditions and dynamics of individual clouds in the NLR; (3) the structure and physical conditions of the warm reflecting gas; (4) the structure of the obscuring torus; (5) the population and morphology of nuclear disks/tori in AGN; (6) the physical conditions in nuclear disks; and (7) the masses of central black holes in AGN. We will use the Hubble Space Telescope (HST) to obtain high-resolution images and spatially resolved spectra. Far-UV spectroscopy of emission and absorption in the nuclear regions using HST/FOS and the Hopkins Ultraviolet Telescope (HUT) will help establish physical conditions in the absorbing and emitting gas. By correlating the dynamics and physical conditions of the gas with the morphology revealed through our imaging program, we will be able to examine mechanisms for fueling the central engine and transporting angular momentum. The kinematics of the nuclear gas disks may enable us to measure the mass of the central black hole. Contemporaneous X-ray observations using ASCA will further constrain the ionization structure of any absorbing material. Monitoring of variability in the UV and X-ray absorption will be used to determine the location of the absorbing gas, possibly in the outflowing warm reflecting gas, or the broad-line region, or the atmosphere of the obscuring torus. Supporting ground-based observations in the optical, near-IR, imaging polarimetry, and the radio will complete our picture of the nuclear structures. With a comprehensive survey of these characteristics in a complete sample of nearby AGN, our

  6. Fluid-structure interaction analysis applied to thermal barrier coated cooled rocket thrust chambers with subsequent local investigation of delamination phenomena

    NASA Astrophysics Data System (ADS)

    Kowollik, D. S. C.; Horst, P.; Haupt, M. C.

    2013-03-01

    The aim of this work is to investigate numerically thermal barrier coating (TBC) systems applied to realistic rocket thrust chamber conditions. A global full parametric three-dimensional (3D) modeling approach for cooled rocket thrust chambers is presented to be able to simulate the fluid-structure interaction (FSI) phenomena involved. In a subsequent analysis step, realistic mechanical and thermal boundary conditions are extracted from critical design regions of the global model and applied to a local finite element model (FEM) to analyze possible TBC delaminations by means of a Fracture Mechanics (FM) approach.

  7. Use of hypometabolic TRIS extenders and high cooling rate refrigeration for cryopreservation of stallion sperm: presence and sensitivity of 5' AMP-activated protein kinase (AMPK).

    PubMed

    Córdova, Alex; Strobel, Pablo; Vallejo, Andrés; Valenzuela, Pamela; Ulloa, Omar; Burgos, Rafael A; Menarim, Bruno; Rodríguez-Gil, Joan Enric; Ratto, Marcelo; Ramírez-Reveco, Alfredo

    2014-12-01

    This study evaluated the effect of the use of hypometabolic TRIS extenders in the presence or the absence of AMPK activators as well as the utilization of high cooling rates in the refrigeration step on the freezability of stallion sperm. Twelve ejaculates were cryopreserved using Botucrio® as a control extender and a basic TRIS extender (HM-0) separately supplemented with 10 mM metformin, 2mM 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR), 2 mM Adenosine monophosphate (AMP), 40 μM compound C AMPK inhibitor or 2 mM AMP+40 μM compound C. Our results showed that the utilization of a hypometabolic TRIS extender supplemented or not with AMP or metformin significantly improves stallion sperm freezability when compared with a commercial extender. Additionally, high cooling rates do not affect stallion sperm quality after cooling and post-thawing. Finally, stallion spermatozoa present several putative AMPK sperm isoforms that do not seem to respond to classical activators, but do respond to the Compound C inhibitor.

  8. Latent TGF-[beta] structure and activation

    SciTech Connect

    Shi, Minlong; Zhu, Jianghai; Wang, Rui; Chen, Xing; Mi, Lizhi; Walz, Thomas; Springer, Timothy A.

    2011-09-16

    Transforming growth factor (TGF)-{beta} is stored in the extracellular matrix as a latent complex with its prodomain. Activation of TGF-{beta}1 requires the binding of {alpha}v integrin to an RGD sequence in the prodomain and exertion of force on this domain, which is held in the extracellular matrix by latent TGF-{beta} binding proteins. Crystals of dimeric porcine proTGF-{beta}1 reveal a ring-shaped complex, a novel fold for the prodomain, and show how the prodomain shields the growth factor from recognition by receptors and alters its conformation. Complex formation between {alpha}v{beta}6 integrin and the prodomain is insufficient for TGF-{beta}1 release. Force-dependent activation requires unfastening of a 'straitjacket' that encircles each growth-factor monomer at a position that can be locked by a disulphide bond. Sequences of all 33 TGF-{beta} family members indicate a similar prodomain fold. The structure provides insights into the regulation of a family of growth and differentiation factors of fundamental importance in morphogenesis and homeostasis.

  9. SIMULATING THE COOLING FLOW OF COOL-CORE CLUSTERS

    SciTech Connect

    Li Yuan; Bryan, Greg L.

    2012-03-01

    We carry out high-resolution adaptive mesh refinement simulations of a cool core cluster, resolving the flow from Mpc scales down to pc scales. We do not (yet) include any active galactic nucleus (AGN) heating, focusing instead on cooling in order to understand how gas reaches the supermassive black hole at the center of the cluster. We find that, as the gas cools, the cluster develops a very flat temperature profile, undergoing a cooling catastrophe only in the central 10-100 pc of the cluster. Outside of this region, the flow is smooth, with no local cooling instabilities, and naturally produces very little low-temperature gas (below a few keV), in agreement with observations. The gas cooling in the center of the cluster rapidly forms a thin accretion disk. The amount of cold gas produced at the very center grows rapidly until a reasonable estimate of the resulting AGN heating rate (assuming even a moderate accretion efficiency) would overwhelm cooling. We argue that this naturally produces a thermostat which links the cooling of gas out to 100 kpc with the cold gas accretion in the central 100 pc, potentially closing the loop between cooling and heating. Isotropic heat conduction does not affect the result significantly, but we show that including the potential well of the brightest cluster galaxy is necessary to obtain the correct result. Also, we found that the outcome is sensitive to resolution, requiring very high mass resolution to correctly reproduce the small transition radius.

  10. Cooling device

    SciTech Connect

    Teske, L.

    1984-02-21

    A cooling device is claimed for coal dust comprising a housing, a motor-driven conveyor system therein to transport the coal dust over coolable trays in the housing and conveyor-wheel arms of spiral curvature for moving the coal dust from one or more inlets to one or more outlets via a series of communicating passages in the trays over which the conveyor-wheel arms pass under actuation of a hydraulic motor mounted above the housing and driving a vertical shaft, to which the conveyor-wheel arms are attached, extending centrally downwardly through the housing.

  11. REACTOR COOLING

    DOEpatents

    Quackenbush, C.F.

    1959-09-29

    A nuclear reactor with provisions for selectively cooling the fuel elements is described. The reactor has a plurality of tubes extending throughout. Cylindrical fuel elements are disposed within the tubes and the coolant flows through the tubes and around the fuel elements. The fuel elements within the central portion of the reactor are provided with roughened surfaces of material. The fuel elements in the end portions of the tubes within the reactor are provlded with low conduction jackets and the fuel elements in the region between the central portion and the end portions are provided with smooth surfaces of high heat conduction material.

  12. Design and implementation of active members for precision space structures

    NASA Technical Reports Server (NTRS)

    Webster, M. S.; Fanson, J. L.; Lurie, B. J.; O'Brien, J. F.

    1992-01-01

    This paper describes the development and implementation of an active member in a precision truss structure. The active member utilizes a piezoelectric actuator motor imbedded in a steel case with built-in displacement sensor. This active member is used in structural quieting. Collocated active damping control loops are designed in order to impedance match piezoelectric active members to the structure. Results from application of these controllers and actuators to the JPL Phase B testbed are given.

  13. Design Concepts for Cooled Ceramic Matrix Composite Turbine Vanes

    NASA Technical Reports Server (NTRS)

    Boyle, Robert

    2014-01-01

    This project demonstrated that higher temperature capabilities of ceramic matrix composites (CMCs) can be used to reduce emissions and improve fuel consumption in gas turbine engines. The work involved closely coupling aerothermal and structural analyses for the first-stage vane of a high-pressure turbine (HPT). These vanes are actively cooled, typically using film cooling. Ceramic materials have structural and thermal properties different from conventional metals used for the first-stage HPT vane. This project identified vane configurations that satisfy CMC structural strength and life constraints while maintaining vane aerodynamic efficiency and reducing vane cooling to improve engine performance and reduce emissions. The project examined modifications to vane internal configurations to achieve the desired objectives. Thermal and pressure stresses are equally important, and both were analyzed using an ANSYS® structural analysis. Three-dimensional fluid and heat transfer analyses were used to determine vane aerodynamic performance and heat load distributions.

  14. Microgravity experiments on boiling and applications: research activity of advanced high heat flux cooling technology for electronic devices in Japan.

    PubMed

    Suzuki, Koichi; Kawamura, Hiroshi

    2004-11-01

    Research and development on advanced high heat flux cooling technology for electronic devices has been carried out as the Project of Fundamental Technology Development for Energy Conservation, promoted by the New Energy and Industrial Technology Development Organization of Japan (NEDO). Based on the microgravity experiments on boiling heat transfer, the following useful results have obtained for the cooling of electronic devices. In subcooled flow boiling in a small channel, heat flux increases considerably more than the ordinary critical heat flux with microbubble emission in transition boiling, and dry out of the heating surface is disturbed. Successful enhancement of heat transfer is achieved by a capillary effect from grooved surface dual subchannels on the liquid supply. The critical heat flux increases 30-40 percent more than for ordinary subchannels. A self-wetting mechanism has been proposed, following investigation of bubble behavior in pool boiling of binary mixtures under microgravity. Ideas and a new concept have been proposed for the design of future cooling system in power electronics.

  15. Nicotinamide mononucleotide adenylyltransferase maintains active zone structure by stabilizing Bruchpilot

    PubMed Central

    Zang, Shaoyun; Ali, Yousuf O; Ruan, Kai; Zhai, R Grace

    2013-01-01

    Active zones are specialized presynaptic structures critical for neurotransmission. We show that a neuronal maintenance factor, nicotinamide mononucleotide adenylyltransferase (NMNAT), is required for maintaining active zone structural integrity in Drosophila by interacting with the active zone protein, Bruchpilot (BRP), and shielding it from activity-induced ubiquitin–proteasome-mediated degradation. NMNAT localizes to the peri-active zone and interacts biochemically with BRP in an activity-dependent manner. Loss of NMNAT results in ubiquitination, mislocalization and aggregation of BRP, and subsequent active zone degeneration. We propose that, as a neuronal maintenance factor, NMNAT specifically maintains active zone structure by direct protein–protein interaction. PMID:23154466

  16. The dance of heating and cooling in galaxy clusters: three-dimensional simulations of self-regulated active galactic nuclei outflows

    NASA Astrophysics Data System (ADS)

    Gaspari, M.; Melioli, C.; Brighenti, F.; D'Ercole, A.

    2011-02-01

    It is now widely accepted that heating processes play a fundamental role in galaxy clusters, struggling in an intricate but fascinating ‘dance' with its antagonist, radiative cooling. Last-generation observations, especially X-ray, are giving us tiny hints about the notes of this endless ballet. Cavities, shocks, turbulence and wide absorption lines indicate that the central active nucleus is injecting a huge amount of energy in the intracluster medium. However, which is the real dominant engine of self-regulated heating? One of the models we propose is massive subrelativistic outflows, probably generated by a wind disc or just the result of the entrainment on kpc scale by the fast radio jet. Using a modified version of the adaptive mesh refinement code FLASH 3.2, we have explored several feedback mechanisms that self-regulate the mechanical power. Two are the best schemes that answer our primary question, that is, quenching cooling flow and at the same time preserving a cool core appearance for a long-term evolution (7 Gyr): one is more explosive (with efficiencies ˜ 5 × 10-3-10-2), triggered by central cooled gas, and the other is gentler, ignited by hot gas Bondi accretion (with ɛ= 0.1). These three-dimensional simulations show that the total energy injected is not the key aspect, but the results strongly depend on how energy is given to the intracluster medium. We follow the dynamics of the best models (temperature, density, surface brightness maps and profiles) and produce many observable predictions: buoyant bubbles, ripples, turbulence, iron abundance maps and hydrostatic equilibrium deviation. We present an in-depth discussion of the merits and flaws of all our models, with a critical eye towards observational concordance.

  17. Transpiration Cooling Experiment

    NASA Technical Reports Server (NTRS)

    Song, Kyo D.; Ries, Heidi R.; Scotti, Stephen J.; Choi, Sang H.

    1997-01-01

    The transpiration cooling method was considered for a scram-jet engine to accommodate thermally the situation where a very high heat flux (200 Btu/sq. ft sec) from hydrogen fuel combustion process is imposed to the engine walls. In a scram-jet engine, a small portion of hydrogen fuel passes through the porous walls of the engine combustor to cool the engine walls and at the same time the rest passes along combustion chamber walls and is preheated. Such a regenerative system promises simultaneously cooling of engine combustor and preheating the cryogenic fuel. In the experiment, an optical heating method was used to provide a heat flux of 200 Btu/sq. ft sec to the cylindrical surface of a porous stainless steel specimen which carried helium gas. The cooling efficiencies by transpiration were studied for specimens with various porosity. The experiments of various test specimens under high heat flux have revealed a phenomenon that chokes the medium flow when passing through a porous structure. This research includes the analysis of the system and a scaling conversion study that interprets the results from helium into the case when hydrogen medium is used.

  18. Chemical and magnetic properties of rapidly cooled metastable ferri-ilmenite solid solutions - IV: the fine structure of self-reversed thermoremanent magnetization

    NASA Astrophysics Data System (ADS)

    Robinson, Peter; McEnroe, S. A.; Fabian, K.; Harrison, R. J.; Thomas, C. I.; Mukai, H.

    2014-03-01

    Magnetic experiments, a Monte Carlo simulation and transmission electron microscopy observations combine to confirm variable chemical phase separation during quench and annealing of metastable ferri-ilmenite compositions, caused by inhomogeneous Fe-Ti ordering and anti-ordering. Separation begins near interfaces between growing ordered and anti-ordered domains, the latter becoming progressively enriched in ilmenite component, moving the Ti-impoverished hematite component into Fe-enriched diffusion waves near the interfaces. Even when disordered regions are eliminated, Fe-enriched waves persist and enlarge on anti-phase boundaries between growing and shrinking ordered and anti-ordered domains. Magnetic results and conceptual models show that magnetic ordering with falling T initiates in the Fe-enriched wave crests. Although representing only a tiny fraction of material, identified at highest Ts on a field-cooling curve, they control the `pre-destiny' of progressive magnetization at lower T. They can provide a positive magnetic moment in a minority of ordered ferrimagnetic material, which, by exchange coupling, then creates a self-reversed negative moment in the remaining majority. Four Ts or T ranges are recognized on typical field-cooling curves: TPD is the T range of `pre-destination'; TC is the predominant Curie T where major positive magnetization increases sharply; TMAX is where magnetization reaches a positive maximum, beyond which it is outweighed by self-reversed magnetization and TZM is the T where total magnetization passes zero. Disposition of these Ts on cooling curves indicate the fine structure of self-reversed thermoremanent magnetization. These results confirm much earlier suspicions that the `x-phase' responsible for self-reversed magnetization resides in Fe-enriched phase boundaries.

  19. Stability of cooled beams

    NASA Astrophysics Data System (ADS)

    Bosser, J.; Carli, C.; Chanel, M.; Madsen, N.; Maury, S.; Möhl, D.; Tranquille, G.

    2000-02-01

    Because of their high density together with extremely small spreads in betatron frequency and momentum, cooled beams are very vulnerable to incoherent and coherent space-charge effects and instabilities. Moreover, the cooling system itself, i.e. the electron beam in the case of e-cooling, presents large linear and non-linear "impedances" to the circulating ion beam, in addition to the usual beam-environment coupling impedances of the storage ring. Beam blow-up and losses, attributed to such effects, have been observed in virtually all the existing electron cooling rings. The adverse effects seem to be more pronounced in those rings, like CELSIUS, that are equipped with a cooler capable of reaching the presently highest energy (100-300 keV electrons corresponding to 180-560 MeV protons). The stability conditions will be revisited with emphasis on the experience gained at LEAR. It will be argued that for all present coolers, three conditions are necessary (although probably not sufficient) for the stability of intense cold beams: (i) operation below transition energy, (ii) active damping to counteract coherent instability, and (iii) careful control of the e-beam neutralisation. An extrapolation to the future "medium energy coolers", planned to work for (anti)protons of several GeV, will also be attempted.

  20. Sol-gel composite coatings as anti-corrosion barrier for structural materials of lead-bismuth eutectic cooled fast reactor

    NASA Astrophysics Data System (ADS)

    Kasada, Ryuta; Dou, Peng

    2013-09-01

    In order to protect the structural components of lead-bismuth eutectic (LBE) cooled fast breeder reactors (FBRs) from liquid metal corrosion, advanced aluminum-yttrium nano- and micro-composite coatings were developed using an improved sol-gel process, which includes dipping specimens in a Y-added sol-gel solution dispersed with ultrafine α-Al2O3 powders prepared by mechanical milling. Scanning electron microscopy (SEM) and field emission electron probe microprobe analyzer (FE-EPMA) analyses revealed that the coatings are composed of alumina with high density. Accelerated corrosion tests were conducted on coated specimens in liquid LBE at 650 °C under dynamic conditions. After the corrosion tests, no cracking, spallation, erosion and liquid metal (e.g., lead) penetration occurred to the coatings, indicating that the coatings possess an enhanced dynamic LBE corrosion resistance. The superior LBE corrosion resistance is due to the presence of the nano-structured composite particles integrated into the coatings and the addition of trace amount of yttrium. Severe erosion and penetration of liquid Pb occurred to the Al2O3 nano- and micro-composite coatings. After the corrosion tests, no cracking, spallation, erosion and liquid metal (e.g., lead) penetration occurred to the newly-developed aluminum-yttrium nano- and micro-composite coatings, indicating that the coatings possess an enhanced dynamic LBE corrosion resistance. Therefore we can conclude that the coatings possess an enhanced dynamic LBE corrosion resistance under the experimental conditions chosen here. It is a way to protect the structural materials of LBE cooled FBRs from liquid metal corrosion. The much improved corrosion resistance of aluminum-yttrium nano- and micro-composite coatings, relative to Al2O3 nano- and micro-composite coatings, is due to the much higher density and the significantly superior high temperature strength resulting from using of finer Al2O3 seeding particles and adding trace

  1. Analysis of construction conditions affecting the structural response of the cooling tower at Willow Island, West Virginia

    SciTech Connect

    Lew, H.S.; Fattal, S.G.

    1980-07-01

    The initial investigation of the Willow Island cooling tower collapse (NBSIR 78-1578) established that the most probable cause of the collapse was the imposition of construction loads on the tower before the concrete had gained adequate strength. The analysis presented herein responds to questions outside the scope of that investigation which considered only actual conditions existing at the time of the collapse. The present investigation shows that failure would initiate in lift 28 if the concrete strength in that lift is 100 psi (6.9 MPa) or less, and to maintain a safety factor of 2.0, the concrete strength in that lift should be 4000 psi (27.6 MPa). This study also reveals that even if an additional bolt had been introduced between each exterior jumpform beam and the tower, the stresses would not have been relieved enough to prevent failure of lift 28. Finally, it is shown, that if the ground anchor point of the static line had been kept at the location occupied just prior to its last move to a location near the center of the tower, the stresses in the shell due to construction loads would have been relieved to the extent that failure of lift 28 would probably not have occurred.

  2. Observation of winds in cool stars

    NASA Technical Reports Server (NTRS)

    Dupree, A. K.

    1983-01-01

    Sufficient observational material - ultraviolet spectroscopic measures, quantitative optical spectroscopy, and X-ray photometry exists to enable discernment of the presence and character of mass loss in cool stars and to establish meaningful constraints on theoretical models. Two determinants of atmospheric wind structure - temperature and gravity - may suffice in a most superficial way to define the wind and atmospheric structure in a star; however more extensive observations demonstrate the importance of magnetic surface activity and its particular geometrical configuration. Successive observations of an active binary system and a supergiant star reveal that magnetic activity and perhaps mass loss occur on restricted regions of a stellar surface and that long lived structures are present in a wind.

  3. Assessment of Alphamagnetic Spectrometer (AMS) Upper Experiment Structural Configuration Shielding Effectiveness Associated with Change from Cryo-Cooled Magnet to Permanent Magnet

    NASA Technical Reports Server (NTRS)

    Scully, Robert

    2012-01-01

    In the spring of 2010, the Alpha Magnetic Spectrometer 2 (AMS-02) underwent a series of system level electromagnetic interference control measurements, followed by thermal vacuum testing. Shortly after completion of the thermal vacuum testing, the project decided to remove the cryogenically cooled superconducting magnet, and replace it with the original permanent magnet design employed in the earlier AMS- 01 assembly. Doing so necessitated several structural changes, as well as removal or modification of numerous electronic and thermal control devices and systems. At this stage, the project was rapidly approaching key milestone dates for hardware completion and delivery for launch, and had little time for additional testing or assessment of any impact to the electromagnetic signature of the AMS-02. Therefore, an analytical assessment of the radiated emissions behavioural changes associated with the system changes was requested.

  4. The Stability of Radiatively Cooling Jets I. Linear Analysis

    NASA Technical Reports Server (NTRS)

    Hardee, Philip E.; Stone, James M.

    1997-01-01

    The results of a spatial stability analysis of a two-dimensional slab jet, in which optically thin radiative cooling is dynamically important, are presented. We study both magnetized and unmagnetized jets at external Mach numbers of 5 and 20. We model the cooling rate by using two different cooling curves: one appropriate to interstellar gas, and the other to photoionized gas of reduced metallicity. Thus, our results will be applicable to both protostellar (Herbig-Haro) jets and optical jets from active galactic nuclei. We present analytical solutions to the dispersion relations in useful limits and solve the dispersion relations numerically over a broad range of perturbation frequencies. We find that the growth rates and wavelengths of the unstable Kelvin-Helmholtz (K-H) modes are significantly different from the adiabatic limit, and that the form of the cooling function strongly affects the results. In particular, if the cooling curve is a steep function of temperature in the neighborhood of the equilibrium state, then the growth of K-H modes is reduced relative to the adiabatic jet. On the other hand, if the cooling curve is a shallow function of temperature, then the growth of K-H modes can be enhanced relative to the adiabatic jet by the increase in cooling relative to heating in overdense regions. Inclusion of a dynamically important magnetic field does not strongly modify the important differences between an adiabatic jet and a cooling jet, provided the jet is highly supermagnetosonic and not magnetic pressure-dominated. In the latter case, the unstable modes behave more like the transmagnetosonic magnetic pressure-dominated adiabatic limit. We also plot fluid displacement surfaces associated with the various waves in a cooling jet in order to predict the structures that might arise in the nonlinear regime. This analysis predicts that low-frequency surface waves and the lowest order body modes will be the most effective at producing observable features in

  5. Cosmic ray heating in cool core clusters I: diversity of steady state solutions

    NASA Astrophysics Data System (ADS)

    Jacob, Svenja; Pfrommer, Christoph

    2017-01-01

    The absence of large cooling flows in cool core clusters appears to require self-regulated energy feedback by active galactic nuclei (AGNs) but the exact heating mechanism has not yet been identified. Here, we analyse whether a combination of cosmic ray (CR) heating and thermal conduction can offset radiative cooling. To this end, we compile a large sample of 39 cool core clusters and determine steady state solutions of the hydrodynamic equations that are coupled to the CR energy equation. We find solutions that match the observed density and temperature profiles for all our clusters well. Radiative cooling is balanced by CR heating in the cluster centres and by thermal conduction on larger scales, thus demonstrating the relevance of both heating mechanisms. Our mass deposition rates vary by three orders of magnitude and are linearly correlated to the observed star formation rates. Clusters with large mass deposition rates show larger cooling radii and require a larger radial extent of the CR injection function. Interestingly, our sample shows a continuous sequence in cooling properties: clusters hosting radio mini halos are characterised by the largest cooling radii, star formation and mass deposition rates in our sample and thus signal the presence of a higher cooling activity. The steady state solutions support the structural differences between clusters hosting a radio mini halo and those that do not.

  6. Protegrin structure-activity relationships: using homology models of synthetic sequences to determine structural characteristics important for activity.

    PubMed

    Ostberg, Nathan; Kaznessis, Yiannis

    2005-02-01

    The protegrin family of antimicrobial peptides is among the shortest in sequence length while remaining very active against a variety of microorganisms. The major goal of this study is to characterize easily calculated molecular properties, which quantitatively show high correlation with antibacterial activity. The peptides studied have high sequence similarity but vary in activity over more than an order of magnitude. Hence, sequence analysis alone cannot be used to predict activity for these peptides. We calculate structural properties of 62 protegrin and protegrin-analogue peptides and correlate them to experimental activities against six microbe species, as well as hemolytic and cytotoxic activities. Natural protegrins structures were compared with synthetic derivatives using homology modeling, and property descriptors were calculated to determine the characteristics that confer their antimicrobial activity. A structure-activity relationship study of all these peptides provides information about the structural properties that affect activity against different microbial species.

  7. Activity Landscape Plotter: A Web-Based Application for the Analysis of Structure-Activity Relationships.

    PubMed

    González-Medina, Mariana; Méndez-Lucio, Oscar; Medina-Franco, José L

    2017-03-27

    Activity landscape modeling is a powerful method for the quantitative analysis of structure-activity relationships. This cheminformatics area is in continuous growth, and several quantitative and visual approaches are constantly being developed. However, these approaches often fall into disuse due to their limited access. Herein, we present Activity Landscape Plotter as the first freely available web-based tool to automatically analyze structure-activity relationships of compound data sets. Based on the concept of activity landscape modeling, the online service performs pairwise structure and activity relationships from an input data set supplied by the user. For visual analysis, Activity Landscape Plotter generates Structure-Activity Similarity and Dual-Activity Difference maps. The user can interactively navigate through the maps and export all the pairwise structure-activity information as comma delimited files. Activity Landscape Plotter is freely accessible at https://unam-shiny-difacquim.shinyapps.io/ActLSmaps /.

  8. Renewable Heating and Cooling

    EPA Pesticide Factsheets

    Renewable heating and cooling is a set of alternative resources and technologies that can be used in place of conventional heating and cooling technologies for common applications such as water heating, space heating, space cooling and process heat.

  9. Active Structural Fibers for Multifunctional Composite Materials

    DTIC Science & Technology

    2014-05-06

    1. Lin, Y., Zhi, Z. and Sodano, 2012, “Barium Titanate and Barium Strontium Titanate Coated Carbon Fibers for Multifunctional Structural Capacitors...Multifunctional Structural Capacitors Consisting of Barium Titanate and Barium Strontium Titanate Coated Carbon Fibers, 18 th International Conference on... Strontium Titanate Coated SiC Fibers,” Electronic Materials and Applications 2011, Jan. 19 th –21 st Orlando, FL (Invited). 9. Lin, Y., Shaffer

  10. Structural stability and surface activity of sunflower 2S albumins and nonspecific lipid transfer protein.

    PubMed

    Berecz, Bernadett; Mills, E N Clare; Tamás, László; Láng, Ferenc; Shewry, Peter R; Mackie, Alan R

    2010-05-26

    The structural and interfacial properties of five different fractions of sunflower ( Helianthus annuus L.) seed storage proteins were studied. The fractions comprised lipid transfer protein (LTP), the methionine-rich 2S albumin SFA8 (sunflower albumin 8), and three mixtures of non-methionine-rich 2S albumins called Alb1 and Alb2 proteins (sunflower albumins 1 and 2). Heating affected all of the proteins studied, with SFA8 and LTP becoming more surface active than the native proteins after heating and cooling. LTP appeared to be less thermostable than homologous LTPs from other plant species. SFA8 generated the greatest elastic modulus and formed the most stable emulsions, whereas LTP showed poorer emulsification properties. The mixed 2S albumin fractions showed moderate levels of surface activity but had the poorest emulsification properties among the proteins studied.

  11. AIR COOLED NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Szilard, L.

    1958-05-27

    A nuclear reactor of the air-cooled, graphite moderated type is described. The active core consists of a cubicle mass of graphite, approximately 25 feet in each dimension, having horizontal channels of square cross section extending between two of the opposite faces, a plurality of cylindrical uranium slugs disposed in end to end abutting relationship within said channels providing a space in the channels through which air may be circulated, and a cadmium control rod extending within a channel provided in the moderator. Suitable shielding is provlded around the core, as are also provided a fuel element loading and discharge means, and a means to circulate air through the coolant channels through the fuel charels to cool the reactor.

  12. Restaurant food cooling practices.

    PubMed

    Brown, Laura Green; Ripley, Danny; Blade, Henry; Reimann, Dave; Everstine, Karen; Nicholas, Dave; Egan, Jessica; Koktavy, Nicole; Quilliam, Daniela N

    2012-12-01

    Improper food cooling practices are a significant cause of foodborne illness, yet little is known about restaurant food cooling practices. This study was conducted to examine food cooling practices in restaurants. Specifically, the study assesses the frequency with which restaurants meet U.S. Food and Drug Administration (FDA) recommendations aimed at reducing pathogen proliferation during food cooling. Members of the Centers for Disease Control and Prevention's Environmental Health Specialists Network collected data on food cooling practices in 420 restaurants. The data collected indicate that many restaurants are not meeting FDA recommendations concerning cooling. Although most restaurant kitchen managers report that they have formal cooling processes (86%) and provide training to food workers on proper cooling (91%), many managers said that they do not have tested and verified cooling processes (39%), do not monitor time or temperature during cooling processes (41%), or do not calibrate thermometers used for monitoring temperatures (15%). Indeed, 86% of managers reported cooling processes that did not incorporate all FDA-recommended components. Additionally, restaurants do not always follow recommendations concerning specific cooling methods, such as refrigerating cooling food at shallow depths, ventilating cooling food, providing open-air space around the tops and sides of cooling food containers, and refraining from stacking cooling food containers on top of each other. Data from this study could be used by food safety programs and the restaurant industry to target training and intervention efforts concerning cooling practices. These efforts should focus on the most frequent poor cooling practices, as identified by this study.

  13. Cooled artery extension

    NASA Technical Reports Server (NTRS)

    Gernert, Nelson J. (Inventor)

    1990-01-01

    An artery vapor trap. A heat pipe artery is constructed with an extension protruding from the evaporator end of the heat pipe beyond the active area of the evaporator. The vapor migrates into the artery extension because of gravity or liquid displacement, and cooling the extension condenses the vapor to liquid, thus preventing vapor lock in the working portion of the artery by removing vapor from within the active artery. The condensed liquid is then transported back to the evaporator by the capillary action of the artery extension itself or by wick located within the extension.

  14. Cooling apparatus and method

    DOEpatents

    Mayes, James C.

    2009-05-05

    A device and method provide for cooling of a system having an energy source, one or more devices that actively consume energy, and one or more devices that generate heat. The device may include one or more thermoelectric coolers ("TECs") in conductive engagement with at least one of the heat-generating devices, and an energy diverter for diverting at least a portion of the energy from the energy source that is not consumed by the active energy-consuming devices to the TECs.

  15. The Texas horned lizard as model for robust capillary structures for passive directional transport of cooling lubricants

    NASA Astrophysics Data System (ADS)

    Comanns, Philipp; Winands, Kai; Pothen, Mario; Bott, Raya A.; Wagner, Hermann; Baumgartner, Werner

    2016-04-01

    Moisture-harvesting lizards, such as the Texas horned lizard Phrynosoma cornutum, have remarkable adaptations for inhabiting arid regions. Special skin structures, in particular capillary channels in between imbricate overlapping scales, enable the lizard to collect water by capillarity and to transport it to the snout for ingestion. This fluid transport is passive and directional towards the lizard's snout. The directionality is based on geometric principles, namely on a periodic pattern of interconnected half-open capillary channels that narrow and widen. Following a biomimetic approach, these principles were transferred to technical prototype design and manufacturing. Capillary structures, 50 μm to 300 μm wide and approx. 70 μm deep, were realized by use of a pulsed picosecond laser in hot working tool steel, hardened to 52 HRC. In order to achieve highest functionality, strategies were developed to minimize potential structural inaccuracies, which can occur at the bottom of the capillary structures caused by the laser process. Such inaccuracies are in the range of 10 μm to 15 μm and form sub-capillary structures with greater capillary forces than the main channels. Hence, an Acceleration Compensation Algorithm was developed for the laser process to minimize or even avoid these inaccuracies. The capillary design was also identified to have substantial influence; by a hexagonal capillary network of non-parallel capillaries potential influences of sub-capillaries on the functionality were reduced to realize a robust passive directional capillary transport. Such smart surface structures can lead to improvements of technical systems by decreasing energy consumption and increasing the resource efficiency.

  16. The Magnetic Field Geometry of Cool Stars

    NASA Astrophysics Data System (ADS)

    See, Victor; Jardine, Moira; Vidotto, Aline; Donati, Jean-Francois; Folsom, Colin; Boro Saikia, Sudeshna; Bouvier, Jerome; Fares, Rim; Gregory, Scott; Hussain, Gaitee; Jeffers, Sandra; Marsden, Stephen; Morin, Julien; Moutou, Claire; do Nascimento, Jose-Dias, Jr.; Petit, Pascal; Rosen, Lisa; Waite, Ian

    2016-06-01

    Zeeman-Doppler imaging has been used to map the large-scale surface magnetic fields of cool stars across a wide range of stellar masses and rotation periods. The derived field geometries are surprising, with many stars showing strong azimuthal fields that are not observed on the Sun. In this poster, using 100 magnetic maps of over 50 stars, we present results showing how the magnetic field geometry of cool stars varies as a function of fundamental parameters. The stellar mass, and hence internal structure, critically influences the field geometry, although this is modified by the stellar rotation rate. We discuss the implications of these results for dynamo theory and the nature of stellar magnetic activity.

  17. GAS COOLED NUCLEAR REACTORS

    DOEpatents

    Long, E.; Rodwell, W.

    1958-06-10

    A gas-cooled nuclear reactor consisting of a graphite reacting core and reflector structure supported in a containing vessel is described. A gas sealing means is included for sealing between the walls of the graphite structure and containing vessel to prevent the gas coolant by-passing the reacting core. The reacting core is a multi-sided right prismatic structure having a pair of parallel slots around its periphery. The containing vessel is cylindrical and has a rib on its internal surface which supports two continuous ring shaped flexible web members with their radially innermost ends in sealing engagement within the radially outermost portion of the slots. The core structure is supported on ball bearings. This design permits thermal expansion of the core stracture and vessel while maintainirg a peripheral seal between the tvo elements.

  18. Structural health monitoring activities at National Laboratories

    SciTech Connect

    Farrar, C.R.; Doebling, S.W.; James, G.H.; Simmermacher, T.

    1997-09-01

    Sandia National Laboratories and Los Alamos National Laboratory have on-going programs to assess damage in structures and mechanical systems from changes in their dynamic characteristics. This paper provides a summary of how both institutes became involved with this technology, their experience in this field and the directions that their research in this area will be taking in the future.

  19. ACOSS SEVEN (Active Control of Space Structures)

    DTIC Science & Technology

    1981-09-01

    system’s secondary optical element. f. FLEXIBLE FLYER (Trusses, beams, struts & ties) This structural concept consists of a primary plantar truss with...The axial components of the centrifugal forces are re cted by a single, com- pression element (mast) that is coincidental with the axis of rotation

  20. Liquid rocket engine fluid-cooled combustion chambers

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A monograph on the design and development of fluid cooled combustion chambers for liquid propellant rocket engines is presented. The subjects discussed are (1) regenerative cooling, (2) transpiration cooling, (3) film cooling, (4) structural analysis, (5) chamber reinforcement, and (6) operational problems.

  1. Control of sound radiation with active/adaptive structures

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.; Rogers, C. A.; Robertshaw, H. H.

    1992-01-01

    Recent research is discussed in the area of active structural acoustic control with active/adaptive structures. Progress in the areas of structural acoustics, actuators, sensors, and control approaches is presented. Considerable effort has been given to the interaction of these areas with each other due to the coupled nature of the problem. A discussion is presented on actuators bonded to or embedded in the structure itself. The actuators discussed are piezoceramic actuators and shape memory alloy actuators. The sensors discussed are optical fiber sensors, Nitinol fiber sensors, piezoceramics, and polyvinylidene fluoride sensors. The active control techniques considered are state feedback control techniques and least mean square adaptive algorithms. Results presented show that significant progress has been made towards controlling structurally radiated noise by active/adaptive means applied directly to the structure.

  2. 75 FR 68809 - Agency Information Collection Activities: Importation Bond Structure

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-09

    ... Information Collection Activities: Importation Bond Structure AGENCY: U.S. Customs and Border Protection...: Importation Bond Structure. This is a proposed extension and revision of an information collection that was...: Importation Bond Structure. OMB Number: 1651-0050. Form Numbers: 301 and 5297. Abstract: Bonds are used...

  3. Mechanisms underlying the cooling observed within the TTL during the active spells of organized deep convection of the Indian Summer Monsoon with COSMC RO and In-situ Measurements

    NASA Astrophysics Data System (ADS)

    Rao, Kusuma; Reddy, Narendra

    Climate impact of the Asian monsoon as a tropical phenomena has been studied for decades in the past for its tropospheric component. However, the effort towards assessing the role of the Asian summer monsoon in the climate system with focus on the Upper Troposphere into the Lower Stratosphere (UTLS) is being addressed only in the recent times. Deep convective vertical fluxes of water and other chemical species penetrate and ventilate the TTL for redistribution of species in to stratosphere. However, the mechanisms underlying such convective transports are yet to be understood. Our specific goal here is to investigate the impact of organized deep moist convection of the Indian summer monsoon on thermal structure of UTLS, and to understand the underlying mechanisms. Since active monsoon spells are manifestations of organized deep convection embedded with overshooting convective elements, it becomes absolutely imperative to understand the impact of organized monsoon convection on three time scales, namely, (i) super synoptic scales of convectively intense active monsoon spells, (ii) on synoptic time scales of convectively disturbed conditions, and finally on (iii) cloud scales. Impact of deep convection on UTLS processes is examined here based on analysis of COSMIC RO and the METEOSAT data for the period, 2006-2011 and the in-situ measurements available from the national programme, PRWONAM during 2009-10 over the Indian land region and from the International field programme, JASMINE during 1999 over the Bay of Bengal. On all the three time scales during (i) the active monsoon spells, (ii) the disturbed periods and (iii) during the passage of deep core of MCSs, we inferred that the Coldpoint Tropopause Temperatures (CPT) lower at relatively lower CPT Altitudes (CPTA) unlike in the cases determined by normal temperature lapse rates; these unusual cases are described here as ‘Unlike Normal’ cases. TTL thickness shrinks during the convective conditions. During the

  4. Stellar magnetic structure and activity /theory/

    NASA Astrophysics Data System (ADS)

    Weiss, N. O.

    Both the overall behavior of the solar cycle and the underlying fine structure of magnetic fields in the sun have been studied mathematically in some detail. These theories are summarized and different phenomenological models of the solar cycle are reviewed. In order to provide a description of the magnetic fields in late-type stars it is necessary to extrapolate boldly from what is known about the sun. In this way field strengths and configurations can be estimated.

  5. Encountering Death: Structured Activities for Death Awareness.

    ERIC Educational Resources Information Center

    Welch, Ira David; And Others

    This book is intended to be used as a supplement to standard textbooks on death and dying for college students. Chapter 1 "Encountering Death in the Self" builds the foundation for increased self-awareness for the study of death and dying. Chapter 2 "Encountering Death in the Family" provides activities which are appropriate for a wide variety of…

  6. The effect of field cooling on a spin-chiral domain structure in a magnetoelectric helimagnet Ba0.5Sr1.5Zn2Fe12O22

    NASA Astrophysics Data System (ADS)

    Hiraoka, Y.; Tanaka, Y.; Oura, M.; Wakabayashi, Y.; Kimura, T.

    2015-06-01

    Spin-chiral domain structures near a cleaved crystal face of a magnetoelectric helimagnet, Ba0.5Sr1.5Zn2Fe12O22, were examined after various magnetic and electric field-cooling procedures by means of the scanning resonant X-ray microdiffraction technique using circularly polarized X-rays. We have found that the application of a magnetic field (1-2 k Oe) during the field-cooling procedure stabilizes one of the handedness among the two spin-chiral states (left- or right-handed screw structure) and makes nearly a single spin-chiral domain in the vicinity of the cleaved crystal face. However, it makes the degree of the spin chirality spatially inhomogeneous even within a domain. We discuss the observed field-cooling effect in terms of possible formation of spin-chiral domains with "stripe-type" domain walls accompanied by randomly-distributed ferromagnetic islands.

  7. Project S'COOL

    NASA Technical Reports Server (NTRS)

    Green, Carolyn J.; Chambers, Lin H.

    1998-01-01

    The Students Clouds Observations On-Line or S'COOL project was piloted in 1997. It was created with the idea of using students to serve as one component of the validation for the Clouds and the Earth's Radiant Energy System (CERES) instrument which was launched with the Tropical Rainfall Measuring Mission (TRMM) in November, 1997. As part of NASA's Earth Science Enterprise CERES is interested in the role clouds play in regulating our climate. Over thirty schools became involved in the initial thrust of the project. The CERES instrument detects the location of clouds and identifies their physical properties. S'COOL students coordinate their ground truth observations with the exact overpass of the satellite at their location. Their findings regarding cloud type, height, fraction and opacity as well as surface conditions are then reported to the NASA Langley Distributed Active Archive Center (DAAC). The data is then accessible to both the CERES team for validation and to schools for educational application via the Internet. By March of 1998 ninety-three schools, in nine countries had enrolled in the S'COOL project. Joining the United States participants were from schools in Australia, Canada, France, Germany, Norway, Spain, Sweden, and Switzerland. The project is gradually becoming the global project envisioned by the project s creators. As students obtain the requested data useful for the scientists, it was hoped that students with guidance from their instructors would have opportunity and motivation to learn more about clouds and atmospheric science as well.

  8. Jet-cooled laser-induced fluorescence spectroscopy of cyclohexoxy: rotational and fine structure of molecules in nearly degenerate electronic States.

    PubMed

    Liu, Jinjun; Miller, Terry A

    2014-12-26

    The rotational structure of the previously observed B̃(2)A' ← X̃(2)A″ and B̃(2)A' ← Ã(2)A' laser-induced fluorescence spectra of jet-cooled cyclohexoxy radical (c-C6H11O) [ Zu, L.; Liu, J.; Tarczay, G.; Dupré, P; Miller, T. A. Jet-cooled laser spectroscopy of the cyclohexoxy radical. J. Chem. Phys. 2004 , 120 , 10579 ] has been analyzed and simulated using a spectroscopic model that includes the coupling between the nearly degenerate X̃ and à states separated by ΔE. The rotational and fine structure of these two states is reproduced by a 2-fold model using one set of molecular constants including rotational constants, spin-rotation constants (ε's), the Coriolis constant (Aζt), the quenched spin-orbit constant (aζed), and the vibronic energy separation between the two states (ΔE0). The energy level structure of both states can also be reproduced using an isolated-state asymmetric top model with rotational constants and effective spin-rotation constants (ε's) and without involving Coriolis and spin-orbit constants. However, the spin-orbit interaction introduces transitions that have no intensity using the isolated-state model but appear in the observed spectra. The line intensities are well simulated using the 2-fold model with an out-of-plane (b-) transition dipole moment for the B̃ ← X̃ transitions and in-plane (a and c) transition dipole moment for the B̃ ← à transitions, requiring the symmetry for the X̃ (Ã) state to be A″ (A'), which is consistent with a previous determination and opposite to that of isopropoxy, the smallest secondary alkoxy radical. The experimentally determined Ã-X̃ separation and the energy level ordering of these two states with different (A' and A″) symmetries are consistent with quantum chemical calculations. The 2-fold model also enables the independent determination of the two contributions to the Ã-X̃ separation: the relativistic spin-orbit interaction (magnetic effect) and the nonrelativistic

  9. Total lactate dehydrogenase activity of tail muscle is not cold-adapted in nocturnal lizards from cool-temperate habitats.

    PubMed

    Hare, K M; Miller, J H; Clark, A G; Daugherty, C H

    2005-12-01

    The dependence of metabolic processes on temperature constrains the behavior, physiology and ecology of many ectothermic animals. The evolution of nocturnality in lizards, especially in temperate regions, requires adaptations for activity at low temperatures when optimal body temperatures are unlikely to be obtained. We examined whether nocturnal lizards have cold-adapted lactate dehydrogenase (LDH). LDH was chosen as a representative metabolic enzyme. We measured LDH activity of tail muscle in six lizard species (n=123: three nocturnal, two diurnal and one crepuscular) between 5 and 35 degrees C and found no differences in LDH-specific activity or thermal sensitivity among the species. Similarly, the specific activity and thermal sensitivity of LDH were similar between skinks and geckos. Similar enzyme activities among nocturnal and diurnal lizards indicate that there is no selection of temperature specific LDH enzyme activity at any temperature. As many nocturnal lizards actively thermoregulate during the day, LDH may be adapted for a broad range of temperatures rather than adapted specifically for the low temperatures encountered when the animals are active. The total activity of LDH in tropical and temperate lizards is not cold-adapted. More data are required on biochemical adaptations and whole animal thermal preferences before trends can be established.

  10. Dynamically limiting energy consumed by cooling apparatus

    DOEpatents

    Chainer, Timothy J.; David, Milnes P.; Iyengar, Madhusudan K.; Parida, Pritish R.; Schmidt, Roger R.; Schultz, Mark D.

    2015-06-09

    Cooling methods are provided which include providing: one or more coolant-cooled structures associated with an electronics rack, a coolant loop coupled in fluid communication with one or more passages of the coolant-cooled structure(s), one or more heat exchange units coupled to facilitate heat transfer from coolant within the coolant loop, and N controllable components associated with the coolant loop or the heat exchange unit(s), wherein N.gtoreq.1. The N controllable components facilitate circulation of coolant through the coolant loop or transfer of heat from the coolant via the heat exchange unit(s). A controller is also provided to dynamically adjust operation of the N controllable components, based on Z input parameters and one or more specified constraints, and provide a specified cooling to the coolant-cooled structure(s), while limiting energy consumed by the N controllable components, wherein Z.gtoreq.1.

  11. Dynamically limiting energy consumed by cooling apparatus

    DOEpatents

    Chainer, Timothy J.; David, Milnes P.; Iyengar, Madhusudan K.; Parida, Pritish R.; Schmidt, Roger R.; Schultz, Mark D.

    2015-05-26

    Cooling apparatuses and methods are provided which include one or more coolant-cooled structures associated with an electronics rack, a coolant loop coupled in fluid communication with one or more passages of the coolant-cooled structure(s), one or more heat exchange units coupled to facilitate heat transfer from coolant within the coolant loop, and N controllable components associated with the coolant loop or the heat exchange unit(s), wherein N.gtoreq.1. The N controllable components facilitate circulation of coolant through the coolant loop or transfer of heat from the coolant via the heat exchange unit(s). A controller is coupled to the N controllable components, and dynamically adjusts operation of the N controllable components, based on Z input parameters and one or more specified constraints, to provide a specified cooling to the coolant-cooled structure(s), while limiting energy consumed by the N controllable components, wherein Z.gtoreq.1.

  12. Activity and cool spots on the surfaces of G-type stars with superflares from observations with the Kepler Space Telescope

    NASA Astrophysics Data System (ADS)

    Savanov, I. S.; Dmitrienko, E. S.

    2015-09-01

    The properties of active regions (cool spots) on the surfaces of 279 G-type stars in which more than 1500 superflares with energies of 1033-1036 erg were detected are analyzed. Diagrams plotting the superflare energy against activity parameters of the stars (the area of their magnetic spots) are considered, and a more extensive study of the activity of two stars with the highest numbers of flares is presented. The range of variation of the superflare energies (up to two orders of magnitude) is realized over the entire interval of rotation periods. It is proposed that the plot of superflare energy vs. rotational period is bimodal. There are probably no appreciable differences in the maximum flare energies for the two groups of objects, which have rotational periods of more than and less than 10 days. Three groups of stars with different surface spottednesses can be distinguished in a plot of superflare energy vs. cool-spot area. The range of variation of the flare energy within a group is roughly the same for these three groups. Most of the points on this diagram lie to the right of the dependence corresponding to B = 3000Gand an inclination i = 90° (the first two groups of objects). It is confirmed that the flare activity is not related directly to circumpolar active regions, since the majority of the points on the diagram lie to the right of the dependence for B = 1000 G and i = 3°. Analysis of stars from the sample, including objects with more than 20 superflares, shows that large variations of the energy (by up to two orders of magnitude) can be reached with small variations of the spottedness parameter S for a single star. Appreciable variability of the spottedness (by factors of five to six) was detected for only two objects from the sample (KIC 10422252 and KIC 11764567). These stars displayed an increase in the flare energy by orders of magnitude for any spottedness level. The activity of KIC 11551430 and KIC 11764567 is analyzed in detail using all

  13. Impact of Structured Movement Time on Preschoolers' Physical Activity Engagement

    ERIC Educational Resources Information Center

    Palmer, Kara K.; Matsuyama, Abigail L.; Robinson, Leah E.

    2017-01-01

    Preschool-aged children are not meeting national physical activity recommendations. This study compares preschoolers' physical activity engagement during two different physical activity opportunities: outdoor free play or a structured movement session. Eighty-seven children served as participants: 40 children participated in outdoor free play and…

  14. Antiproliferative and Structure Activity Relationships of Amaryllidaceae Alkaloids.

    PubMed

    Cedrón, Juan C; Ravelo, Ángel G; León, Leticia G; Padrón, José M; Estévez-Braun, Ana

    2015-07-30

    The antiproliferative activity of a set of seven natural Amaryllidaceae alkaloids and 32 derivatives against four cancer cell lines (A2780, SW1573, T47-D and WiDr) was determined. The best antiproliferative activities were achieved with alkaloids derived from pancracine (2), haemanthamine (6) and haemantidine (7). For each skeleton, some structure-activity relationships were outlined.

  15. Preliminary study on nano- and micro-composite sol-gel based alumina coatings on structural components of lead-bismuth eutectic cooled fast breeder reactors

    NASA Astrophysics Data System (ADS)

    Dou, Peng; Kasada, Ryuta

    2011-02-01

    In order to protect the structural components of lead-bismuth eutectic cooled fast breeder reactors from liquid metal corrosion, Al 2O 3 nano- and micro-composite coatings were developed using an improved sol-gel process, which includes dipping specimens in a sol-gel solution dispersed with fine α-Al 2O 3 powders prepared by mechanical milling. Accelerated corrosion tests were conducted on coated specimens in liquid lead-bismuth eutectic at 500 °C under dynamic conditions. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed that the coatings are composed of α-Al 2O 3 and they are about 10 μm thick. After the corrosion tests, no spallation occurred on the coatings, and neither Pb nor Bi penetrated into the coatings, which indicates that the coatings possess an enhanced dynamic LBE corrosion resistance to lead-bismuth eutectic corrosion. The nano-structured composite particles integrated into the coatings play an important role in achieving such superior lead-bismuth eutectic corrosion resistance.

  16. Characterizing the effects of elevated temperature on the air void pore structure of advanced gas-cooled reactor pressure vessel concrete using x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Stein, R. C.; Petkovski, M.; Engelberg, D. L.; Leonard, F.; Withers, P. J.

    2013-07-01

    X-ray computed tomography (X-ray CT) has been applied to nondestructively characterise changes in the microstructure of a concrete used in the pressure vessel structure of Advanced Gas-cooled Reactors (AGR) in the UK. Concrete specimens were conditioned at temperatures of 105 °C and 250 °C, to simulate the maximum thermal load expected to occur during a loss of coolant accident (LOCA). Following thermal treatment, these specimens along with an unconditioned control sample were characterised using micro-focus X-ray CT with a spatial resolution of 14.6 microns. The results indicate that the air void pore structure of the specimens experienced significant volume changes as a result of the increasing temperature. The increase in the porous volume was more prevalent at 250 °C. Alterations in air void size distributions were characterized with respect to the unconditioned control specimen. These findings appear to correlate with changes in the uni-axial compressive strength of the conditioned concrete.

  17. Peltier-Cooled and Actively Quenched Operation of InGaAs/InP Avalanche Photodiodes as Photon Counters at a 1.55-mum Wavelength.

    PubMed

    Prochazka, I

    2001-11-20

    The performance of commercially available InGaAs/InP avalanche photodiodes as single-photon detectors at a 1.55-mum wavelength has been investigated. A new active quenching and gating circuit, tailored for operation of these diodes at temperatures in the range from room temperature to -60 degrees C and achievable by means of thermoelectrical cooling, has been developed. Careful tuning of the diodes' operating conditions resulted in a significant reduction of afterpulsing effects; it permitted operation of the detectors with high repetition rates. A noise-equivalent power of 7 x 10(-16) W/Hz(1/2) was obtained at a 1.55-mum wavelength.

  18. Origami-inspired active structures: a synthesis and review

    NASA Astrophysics Data System (ADS)

    Peraza-Hernandez, Edwin A.; Hartl, Darren J.; Malak, Richard J., Jr.; Lagoudas, Dimitris C.

    2014-09-01

    Origami, the ancient art of paper folding, has inspired the design of engineering devices and structures for decades. The underlying principles of origami are very general, which has led to applications ranging from cardboard containers to deployable space structures. More recently, researchers have become interested in the use of active materials (i.e., those that convert various forms of energy into mechanical work) to effect the desired folding behavior. When used in a suitable geometry, active materials allow engineers to create self-folding structures. Such structures are capable of performing folding and/or unfolding operations without being kinematically manipulated by external forces or moments. This is advantageous for many applications including space systems, underwater robotics, small scale devices, and self-assembling systems. This article is a survey and analysis of prior work on active self-folding structures as well as methods and tools available for the design of folding structures in general and self-folding structures in particular. The goal is to provide researchers and practitioners with a systematic view of the state-of-the-art in this important and evolving area. Unifying structural principles for active self-folding structures are identified and used as a basis for a quantitative and qualitative comparison of numerous classes of active materials. Design considerations specific to folded structures are examined, including the issues of crease pattern identification and fold kinematics. Although few tools have been created with active materials in mind, many of them are useful in the overall design process for active self-folding structures. Finally, the article concludes with a discussion of open questions for the field of origami-inspired engineering.

  19. Cool barnacles: Do common biogenic structures enhance or retard rates of deterioration of intertidal rocks and concrete?

    PubMed

    Coombes, Martin A; Viles, Heather A; Naylor, Larissa A; La Marca, Emanuela Claudia

    2017-02-15

    Sedentary and mobile organisms grow profusely on hard substrates within the coastal zone and contribute to the deterioration of coastal engineering structures and the geomorphic evolution of rocky shores by both enhancing and retarding weathering and erosion. There is a lack of quantitative evidence for the direction and magnitude of these effects. This study assesses the influence of globally-abundant intertidal organisms, barnacles, by measuring the response of limestone, granite and marine-grade concrete colonised with varying percentage covers of Chthamalus spp. under simulated, temperate intertidal conditions. Temperature regimes at 5 and 10mm below the surface of each material demonstrated a consistent and statistically significant negative relationship between barnacle abundance and indicators of thermal breakdown. With a 95% cover of barnacles, subsurface peak temperatures were reduced by 1.59°C for limestone, 5.54°C for concrete and 5.97°C for granite in comparison to no barnacle cover. The amplitudes of short-term (15-30min) thermal fluctuations conducive to breakdown via 'fatigue' effects were also buffered by 0.70°C in limestone, 1.50°C in concrete and 1.63°C in granite. Furthermore, concentrations of potentially damaging salt ions were consistently lower under barnacles in limestone and concrete. These results indicate that barnacles do not enhance, but likely reduce rates of mechanical breakdown on rock and concrete by buffering near-surface thermal cycling and reducing salt ion ingress. In these ways, we highlight the potential role of barnacles as agents of bioprotection. These findings support growing international efforts to enhance the ecological value of hard coastal structures by facilitating their colonisation (where appropriate) through design interventions.

  20. Hybrid radiator cooling system

    SciTech Connect

    France, David M.; Smith, David S.; Yu, Wenhua; Routbort, Jules L.

    2016-03-15

    A method and hybrid radiator-cooling apparatus for implementing enhanced radiator-cooling are provided. The hybrid radiator-cooling apparatus includes an air-side finned surface for air cooling; an elongated vertically extending surface extending outwardly from the air-side finned surface on a downstream air-side of the hybrid radiator; and a water supply for selectively providing evaporative cooling with water flow by gravity on the elongated vertically extending surface.

  1. Structural Determinants of Sleeping Beauty Transposase Activity.

    PubMed

    Abrusán, György; Yant, Stephen R; Szilágyi, András; Marsh, Joseph A; Mátés, Lajos; Izsvák, Zsuzsanna; Barabás, Orsolya; Ivics, Zoltán

    2016-08-01

    Transposases are important tools in genome engineering, and there is considerable interest in engineering more efficient ones. Here, we seek to understand the factors determining their activity using the Sleeping Beauty transposase. Recent work suggests that protein coevolutionary information can be used to classify groups of physically connected, coevolving residues into elements called "sectors", which have proven useful for understanding the folding, allosteric interactions, and enzymatic activity of proteins. Using extensive mutagenesis data, protein modeling and analysis of folding energies, we show that (i) The Sleeping Beauty transposase contains two sectors, which span across conserved domains, and are enriched in DNA-binding residues, indicating that the DNA binding and endonuclease functions of the transposase coevolve; (ii) Sector residues are highly sensitive to mutations, and most mutations of these residues strongly reduce transposition rate; (iii) Mutations with a strong effect on free energy of folding in the DDE domain of the transposase significantly reduce transposition rate. (iv) Mutations that influence DNA and protein-protein interactions generally reduce transposition rate, although most hyperactive mutants are also located on the protein surface, including residues with protein-protein interactions. This suggests that hyperactivity results from the modification of protein interactions, rather than the stabilization of protein fold.

  2. Structural determinants of Sleeping Beauty transposase activity

    PubMed Central

    Abrusán, György; Yant, Stephen R.; Szilágyi, András; Marsh, Joseph A.; Mátés, Lajos; Izsvák, Zsuzsanna; Barabás, Orsolya; Ivics, Zoltán

    2016-01-01

    Transposases are important tools in genome engineering, and there is considerable interest in engineering more efficient ones. Here we seek to understand the factors determining their activity using the Sleeping Beauty transposase. Recent work suggests that protein co-evolutionary information can be used to classify groups of physically connected, co-evolving residues into elements called ‘sectors’, which have proven useful for understanding the folding, allosteric interactions, and enzymatic activity of proteins. Using extensive mutagenesis data, protein modeling and analysis of folding energies, we show that 1) The Sleeping Beauty transposase contains two sectors, which span across conserved domains, and are enriched in DNA-binding residues, indicating that the DNA binding and endonuclease functions of the transposase coevolve; 2) Sector residues are highly sensitive to mutations, and most mutations of these residues strongly reduce transposition rate; 3) Mutations with a strong effect on free energy of folding in the DDE domain of the transposase significantly reduce transposition rate. 4) Mutations that influence DNA and protein-protein interactions generally reduce transposition rate, although most hyperactive mutants are also located on the protein surface, including residues with protein-protein interactions. This suggests that hyperactivity results from the modification of protein interactions, rather than the stabilization of protein fold. PMID:27401040

  3. Cooled, temperature controlled electrometer

    DOEpatents

    Morgan, John P.

    1992-08-04

    A cooled, temperature controlled electrometer for the measurement of small currents. The device employs a thermal transfer system to remove heat from the electrometer circuit and its environment and dissipate it to the external environment by means of a heat sink. The operation of the thermal transfer system is governed by a temperature regulation circuit which activates the thermal transfer system when the temperature of the electrometer circuit and its environment exceeds a level previously inputted to the external variable temperature control circuit. The variable temperature control circuit functions as subpart of the temperature control circuit. To provide temperature stability and uniformity, the electrometer circuit is enclosed by an insulated housing.

  4. Cooled, temperature controlled electrometer

    DOEpatents

    Morgan, John P.

    1992-01-01

    A cooled, temperature controlled electrometer for the measurement of small currents. The device employs a thermal transfer system to remove heat from the electrometer circuit and its environment and dissipate it to the external environment by means of a heat sink. The operation of the thermal transfer system is governed by a temperature regulation circuit which activates the thermal transfer system when the temperature of the electrometer circuit and its environment exceeds a level previously inputted to the external variable temperature control circuit. The variable temperature control circuit functions as subpart of the temperature control circuit. To provide temperature stability and uniformity, the electrometer circuit is enclosed by an insulated housing.

  5. Active structural subsystem of the OISI interferometry testbed

    NASA Astrophysics Data System (ADS)

    Döngi, Frank; Johann, Ulrich; Szerdahelyi, Laszlo

    1999-12-01

    An adaptive truss structure has been realized for active vibration damping within a laboratory testbed for future spaceborne optical and infra-red interferometers. The active elements are based on piezoelectric sensors and actuators. The paper first surveys configuration scenarios for space interferometers that aim at nanometre accuracy of optical pathlengths. It then focuses on the function of active structural control. For the laboratory truss, practical design considerations as well as analytical approaches for modelling and system identification, placement of active elements and design of active damping control are discussed in detail. Experimental results of the active damping performance achieved with integral feedback of strut force signals are compared with analytical predictions. The combined effects of active damping and passive vibration isolation are presented, and conclusions are drawn regarding further activities towards nanometre stabilization of optical pathlengths.

  6. Structural damage detection using active members and neural networks

    NASA Astrophysics Data System (ADS)

    Manning, R. A.

    1994-06-01

    The detection of damage in structures is a topic which has considerable interest in many fields. In the past many methods for detecting damage in structures has relied on finite element model refinement methods. This note presents a structural damage methodology in which only active member transfer function data are used in conjunction with an artificial neural network to detect damage in structures. Specifically, the method relies on training a neural network using active member transfer function pole/zero information to classify damaged structure measurements and to predict the degree of damage in the structure. The method differs from many of the past damage detection algorithms in that no attempt is made to update a finite element model or to match measured data with new finite element analyses of the structure in a damaged state.

  7. Active control of sound transmission using structural modal filters

    NASA Astrophysics Data System (ADS)

    Kaizuka, Tsutomu; Tanaka, Nobuo; Nakano, Kimihiko

    2016-10-01

    This paper addresses active sound transmission control based on structural sensors and actuators. The proposed methodology is to independently measure and control the targeted structural modes, which significantly contribute to sound transmission, with structural modal filters, i.e., modal sensors and modal actuators. The targeting is performed by using modal sound transmission coefficients before control as the criteria. The modal sound transmission coefficient enables the contribution from a structural mode to the sound transmission via the modal interaction with the other structural modes to be determined. The structural modal filters effectively facilitate decreasing the sound transmission and guarantee that the structural vibration and near-field sound, side effects of sound transmission control, will not increase. It is shown with numerical examples that sound transmission can be reduced significantly in a broad frequency band by controlling a small number of structural modes and neither the structural vibration nor near-field sound are increased.

  8. Lead-Cooled Fast Reactor (LFR) Design: Safety, Neutronics, Thermal Hydraulics, Structural Mechanics, Fuel, Core, and Plant Design

    SciTech Connect

    Smith, C

    2010-02-22

    The idea of developing fast spectrum reactors with molten lead (or lead alloy) as a coolant is not a new one. Although initially considered in the West in the 1950s, such technology was not pursued to completion because of anticipated difficulties associated with the corrosive nature of these coolant materials. However, in the Soviet Union, such technology was actively pursued during the same time frame (1950s through the 1980s) for the specialized role of submarine propulsion. More recently, there has been a renewal of interest in the West for such technology, both for critical systems as well as for Accelerator Driven Subcritical (ADS) systems. Meanwhile, interest in the former Soviet Union, primarily Russia, has remained strong and has expanded well beyond the original limited mission of submarine propulsion. This section reviews the past and current status of LFR development.

  9. Structural snapshots of actively translating human ribosomes.

    PubMed

    Behrmann, Elmar; Loerke, Justus; Budkevich, Tatyana V; Yamamoto, Kaori; Schmidt, Andrea; Penczek, Pawel A; Vos, Matthijn R; Bürger, Jörg; Mielke, Thorsten; Scheerer, Patrick; Spahn, Christian M T

    2015-05-07

    Macromolecular machines, such as the ribosome, undergo large-scale conformational changes during their functional cycles. Although their mode of action is often compared to that of mechanical machines, a crucial difference is that, at the molecular dimension, thermodynamic effects dominate functional cycles, with proteins fluctuating stochastically between functional states defined by energetic minima on an energy landscape. Here, we have used cryo-electron microscopy to image ex-vivo-derived human polysomes as a source of actively translating ribosomes. Multiparticle refinement and 3D variability analysis allowed us to visualize a variety of native translation intermediates. Significantly populated states include not only elongation cycle intermediates in pre- and post-translocational states, but also eEF1A-containing decoding and termination/recycling complexes. Focusing on the post-translocational state, we extended this assessment to the single-residue level, uncovering striking details of ribosome-ligand interactions and identifying both static and functionally important dynamic elements.

  10. Self-Cooling Gradient Shell for Body Armor

    DTIC Science & Technology

    2012-05-10

    hydrophilic gradient fabric for directional water transport inside of the cooling system. thermal burden, SDSC, cooling, evaporative, textile U U U UU...high expenses associated with the purchasing of the manikin. This method/apparatus was used to demonstrate the cooling capacity of novel smart textile ...materials for advanced, light-weight, self-cooling protective clothing. Passive cooling was accomplished by creating a laminated structure with a

  11. Active damping of spacecraft structural appendage vibrations

    NASA Technical Reports Server (NTRS)

    Fedor, Joseph V. (Inventor)

    1990-01-01

    An active vibration damper system, for bending in two orthogonal directions and torsion, in each of three mutually perpendicular axes is located at the extremities of the flexible appendages of a space platform. The system components for each axis includes: an accelerometer, filtering and signal processing apparatus, and a DC motor-inertia wheel torquer. The motor torquer, when driven by a voltage proportional to the relative vibration tip velocity, produces a reaction torque for opposing and therefore damping a specific modal velocity of vibration. The relative tip velocity is obtained by integrating the difference between the signal output from the accelerometer located at the end of the appendage with the output of a usually carried accelerometer located on a relatively rigid body portion of the space platform. A selector switch, with sequential stepping logic or highest modal vibration energy logic, steps to another modal tip velocity channel and receives a signal voltage to damp another vibration mode. In this manner, several vibration modes can be damped with a single sensor/actuator pair. When a three axis damper is located on each of the major appendages of the platform, then all of the system vibration modes can be effectively damped.

  12. Liquid metal cooled nuclear reactor plant system

    DOEpatents

    Hunsbedt, Anstein; Boardman, Charles E.

    1993-01-01

    A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting for fuel decay during reactor shutdown, or heat produced during a mishap. The reactor system is enhanced with sealing means for excluding external air from contact with the liquid metal coolant leaking from the reactor vessel during an accident. The invention also includes a silo structure which resists attack by leaking liquid metal coolant, and an added unique cooling means.

  13. Development of magnetostrictive active members for control of space structures

    NASA Technical Reports Server (NTRS)

    Johnson, Bruce G.; Avakian, Kevin M.; Fenn, Ralph C.; Gaffney, Monique S.; Gerver, Michael J.; Hawkey, Timothy J.; Boudreau, Donald J.

    1992-01-01

    The goal of this Phase 2 Small Business Innovative Research (SBIR) project was to determine the technical feasibility of developing magnetostrictive active members for use as truss elements in space structures. Active members control elastic vibrations of truss-based space structures and integrate the functions of truss structure element, actively controlled actuator, and sensor. The active members must control structural motion to the sub-micron level and, for many proposed space applications, work at cryogenic temperatures. Under this program both room temperature and cryogenic temperature magnetostrictive active members were designed, fabricated, and tested. The results of these performance tests indicated that room temperature magnetostrictive actuators feature higher strain, stiffness, and force capability with lower amplifier requirements than similarly sized piezoelectric or electrostrictive active members, at the cost of higher mass. Two different cryogenic temperature magnetostrictive materials were tested at liquid nitrogen temperatures, both with larger strain capability than the room temperature magnetostrictive materials. The cryogenic active member development included the design and fabrication of a cryostat that allows operation of the cryogenic active member in a space structure testbed.

  14. DEVELOPMENT OF STRUCTURE ACTIVITY RELATIONSHIPS FOR ASSESSING ECOLOGICAL RISKS

    EPA Science Inventory

    In the field of environmental toxicology, structure activity relationships (SARs) have developed as scientifically-credible tools for predicting the effects of chemicals when little or no empirical data are available.

  15. Historical Earthquakes and Active Structure for Georgia

    NASA Astrophysics Data System (ADS)

    Tsereteli, Nino; Varazanashivli, Otar

    2014-05-01

    Long-term seismic history is an important foundation for reliable assessment of seismic hazard and risk. Therefore, completeness of earthquake catalogues in the longest historical part is very important. Survived historical sources, as well as special researches from the institutes, museums, libraries and archives in Georgia, the Caucasus and the Middle East indicate to high level of seismicity which entailed numerous human casualties and destruction on the territory of Georgia during the historical period. The study and detailed analysis of these original documents and researches have allowed us to create a new catalogue of historical earthquakes of Georgia from 1250 BC to 1900 AD. The method of the study is based on a multidisciplinary approach, i.e. on the joint use of methods of history and paleoseismology, archeoseismology, seismotectonics, geomorphology, etc. We present here a new parametric catalogue of 44 historic earthquakes of Georgia and a full "descriptor" of all the phenomena described in it. Constructed on its basis, the summarized map of the distribution of maximum damage in the historical period (before 1900) on the territory of Georgia clearly shows the main features of the seismic field during this period. In particular, in the axial part and the southern slope of the Greater Caucasus there is a seismic gap, which was filled in 1991 by the strongest earthquake and its aftershocks in Racha. In addition, it is also obvious that very high seismic activity in the central and eastern parts of the Javakheti highland is not described in historical materials and this fact requires further searches of various kinds of sources that contain data about historical earthquakes. We hope that this catalogue will enable to create a new joint (instrumental and historical) parametric earthquake catalogue of Georgia and will serve to assess the real seismic hazard and risk in the country.

  16. High-efficiency impurity activation by precise control of cooling rate during atmospheric pressure thermal plasma jet annealing of 4H-SiC wafer

    NASA Astrophysics Data System (ADS)

    Maruyama, Keisuke; Hanafusa, Hiroaki; Ashihara, Ryuhei; Hayashi, Shohei; Murakami, Hideki; Higashi, Seiichiro

    2015-06-01

    We have investigated high-temperature and rapid annealing of a silicon carbide (SiC) wafer by atmospheric pressure thermal plasma jet (TPJ) irradiation for impurity activation. To reduce the temperature gradient in the SiC wafer, a DC current preheating system and the lateral back-and-forth motion of the wafer were introduced. A maximum surface temperature of 1835 °C within 2.4 s without sample breakage was achieved, and aluminum (Al), phosphorus (P), and arsenic (As) activations in SiC were demonstrated. We have investigated precise control of heating rate (Rh) and cooling rate (Rc) during rapid annealing of P+-implanted 4H-SiC and its impact on impurity activation. No dependence of resistivity on Rh was observed, while increasing Rc significantly decreased resistivity. A minimum resistivity of 0.0025 Ω·cm and a maximum carrier concentration of 2.9 × 1020 cm-3 were obtained at Rc = 568 °C/s.

  17. Chemical and biological structure and transport of a cool filament associated with a jet-eddy system of northern California in July 1986 (OPTOMA21)

    NASA Technical Reports Server (NTRS)

    Jones, Burton H.; Mooers, Christopher N. K.; Rienecker, Michele M.; Stanton, Tim; Washburn, Libe

    1991-01-01

    The distributions of nutrient, pigment, bio-optical, and physical variables were mapped in a jet-eddy system off Point Reyes and Point Arena, California, from July 7 to 19, 1986, in order to describe the 3D variability of the filament and its relation to the nutrient and phytoplankton distributions offshore, to examine the interaction between the filament and coastal water, and to estimate the transport of nutrients and phytoplankton by the jet system. Several cool filaments were distinguishable at distances of more than 35-50 km from the coast in satellite imagery during this period. The juxtaposition of these features as well as the presence of an offshore anticyclone and a cyclone south of the filament anchored to the coast at Point Arena led to complex patterns in all variables, aided by the apparent alongshore variability in the source of upwelled water. This structure has implications for the fluxes of organic material in the region and is probably significant in organizing the interactions among different trophic levels within the system.

  18. Manufacturing of agarose-based chromatographic adsorbents--effect of ionic strength and cooling conditions on particle structure and mechanical strength.

    PubMed

    Ioannidis, Nicolas; Bowen, James; Pacek, Andrzej; Zhang, Zhibing

    2012-02-01

    The effect of ionic strength of agarose solution and quenching temperature of the emulsion on the structure and mechanical strength of agarose-based chromatographic adsorbents was investigated. Solutions of agarose containing different amounts of NaCl were emulsified at elevated temperature in mineral oil using a high-shear mixer. The hot emulsion was quenched at different temperatures leading to the gelation of agarose and formation of soft particles. Analysis of Atomic Force Microscopy (AFM) images of particle surfaces shows that pore size of particles increases with ionic strength and/or high quenching temperature. Additionally it has been found that the compressive strength of particles measured by micromanipulation also increases with ionic strength of the emulsion and/or high quenching temperature but these two parameters have no significant effect on the resulting particle size and particle size distribution. Results from both characterization methods were compared with Sepharose 4B, a commercial agarose-based adsorbent. This is the first report examining the effect of ionic strength and cooling conditions on the microstructure of micron-sized agarose beads for bioseparation.

  19. Eliciting Production of L2 Target Structures through Priming Activities

    ERIC Educational Resources Information Center

    McDonough, Kim; Trofimovich, Pavel; Neumann, Heike

    2015-01-01

    This study focuses on the pedagogical applications of structural priming research in an English for academic purposes (EAP) context, investigating whether priming activities are an effective tool for eliciting production of target grammatical structures. University students across four EAP classes carried out a total of 6 information-exchange…

  20. Cooling of the cerebellar interpositus nucleus abolishes somatosensory cortical learning-related activity in eyeblink conditioned rabbits.

    PubMed

    Wikgren, Jan; Lavond, David G; Ruusuvirta, Timo; Korhonen, Tapani

    2006-06-03

    Nictitating membrane movement and multiple-unit activity in the somatosensory cortex were recorded from rabbits during paired (N=6) and unpaired (N=5) presentations of a tone conditioned stimulus (CS) and an airpuff unconditioned stimulus (US). A behavioural conditioned response (CR) to the CS and an accompanying neural response in the somatosensory cortex developed only in the paired group. Inactivation of the cerebellar interpositus nucleus abolished both the acquired CR and the accompanying neural response. However, the CS facilitated both behavioural and neural responses to the US during the inactivation. Thus, the absence of the CR could not be accounted for by the general inability of the CS to alter the behaviour constituting the CR or the activity of the somatosensory cortex. These findings suggest that the efferent copy of the signal related to the eyeblink CR is projected from the cerebellum to the cerebral cortical areas of the US modality.

  1. Spatially-selective optical pumping cooling and Two-Isotope Collision-Assisted Zeeman cooling

    NASA Astrophysics Data System (ADS)

    Wilson, Rebekah Ferrier

    hyperfine-changing collisions to be a significant limitation for the 85/87Rb gas mixture. Possible improvements to this experiment will be discussed as well as the prospects for improved cooling performance using an atom without hyperfine structure as the optically pumped atom.

  2. Opposing Effects of Neuronal Activity on Structural Plasticity

    PubMed Central

    Fauth, Michael; Tetzlaff, Christian

    2016-01-01

    The connectivity of the brain is continuously adjusted to new environmental influences by several activity-dependent adaptive processes. The most investigated adaptive mechanism is activity-dependent functional or synaptic plasticity regulating the transmission efficacy of existing synapses. Another important but less prominently discussed adaptive process is structural plasticity, which changes the connectivity by the formation and deletion of synapses. In this review, we show, based on experimental evidence, that structural plasticity can be classified similar to synaptic plasticity into two categories: (i) Hebbian structural plasticity, which leads to an increase (decrease) of the number of synapses during phases of high (low) neuronal activity and (ii) homeostatic structural plasticity, which balances these changes by removing and adding synapses. Furthermore, based on experimental and theoretical insights, we argue that each type of structural plasticity fulfills a different function. While Hebbian structural changes enhance memory lifetime, storage capacity, and memory robustness, homeostatic structural plasticity self-organizes the connectivity of the neural network to assure stability. However, the link between functional synaptic and structural plasticity as well as the detailed interactions between Hebbian and homeostatic structural plasticity are more complex. This implies even richer dynamics requiring further experimental and theoretical investigations. PMID:27445713

  3. Remarkable transition from rocksalt/perovskite layered structure to fluorite/rocksalt layered structure in rapidly cooled Ln₂CuO₄.

    PubMed

    Patabendige, Chami N K; Azad, Abul K; Connor, Paul A; Rolle, Aurélie; Irvine, John T S

    2013-01-01

    Lanthanide cuprates of formula Ln₂CuO₄ exist in two principal forms, T and T' which are renowned for their exhibition at low temperatures of hole and electronic types of superconductivity, respectively. These structures differ primarily in the arrangement of oxygen between the perovskite layers and also in nature of the copper oxygen planes. The Cu-O distance in the T structure (~1.90 Å) is much shorter than the T' (1.97Å), reflecting a transition between partial Cu⁺and partial Cu³⁺ character. In seeking to find compositions that bridge these two structure/electron carrier types, we observed the transition from a T structure to a T' type structure, resulting in the metastable form T″ with slightly larger volume but similar character to T'. This transition from T to T″ is associated with 5% increase in a and a 5% decrease in c parameters of the tetragonal unit cells, which results in disintegration of ceramic bodies.

  4. A structural pathway for activation of the kinesin motor ATPase

    PubMed Central

    Yun, Mikyung; Zhang, Xiaohua; Park, Cheon-Gil; Park, Hee-Won; Endow, Sharyn A.

    2001-01-01

    Molecular motors move along actin or microtubules by rapidly hydrolyzing ATP and undergoing changes in filament-binding affinity with steps of the nucleotide hydrolysis cycle. It is generally accepted that motor binding to its filament greatly increases the rate of ATP hydrolysis, but the structural changes in the motor associated with ATPase activation are not known. To identify the conformational changes underlying motor movement on its filament, we solved the crystal structures of three kinesin mutants that decouple nucleotide and microtubule binding by the motor, and block microtubule-activated, but not basal, ATPase activity. Conformational changes in the structures include a disordered loop and helices in the switch I region and a visible switch II loop, which is disordered in wild-type structures. Switch I moved closer to the bound nucleotide in two mutant structures, perturbing water-mediated interactions with the Mg2+. This could weaken Mg2+ binding and accelerate ADP release to activate the motor ATPase. The structural changes we observe define a signaling pathway within the motor for ATPase activation that is likely to be essential for motor movement on microtubules. PMID:11387196

  5. Surface modification of active material structures in battery electrodes

    DOEpatents

    Erickson, Michael; Tikhonov, Konstantin

    2016-02-02

    Provided herein are methods of processing electrode active material structures for use in electrochemical cells or, more specifically, methods of forming surface layers on these structures. The structures are combined with a liquid to form a mixture. The mixture includes a surface reagent that chemically reacts and forms a surface layer covalently bound to the structures. The surface reagent may be a part of the initial liquid or added to the mixture after the liquid is combined with the structures. In some embodiments, the mixture may be processed to form a powder containing the structures with the surface layer thereon. Alternatively, the mixture may be deposited onto a current collecting substrate and dried to form an electrode layer. Furthermore, the liquid may be an electrolyte containing the surface reagent and a salt. The liquid soaks the previously arranged electrodes in order to contact the structures with the surface reagent.

  6. Structure-activity relationships of benzothiazole GPR35 antagonists.

    PubMed

    Abdalhameed, Manahil M; Zhao, Pingwei; Hurst, Dow P; Reggio, Patricia H; Abood, Mary E; Croatt, Mitchell P

    2017-02-01

    The first structure-activity relationships for a benzothiazole scaffold acting as an antagonist at GPR35 is presented. Analogues were designed based on a lead compound that was previously determined to have selective activity as a GPR35 antagonist. The synthetic route was modular in nature to independently explore the role of the middle and both ends of the scaffold. The activities of the analogues illustrate the importance of all three segments of the compound.

  7. Structure-activity relationships of benzothiazole GPR35 antagonists

    PubMed Central

    Abdalhameed, Manahil M.; Zhao, Pingwei; Hurst, Dow P.; Reggio, Patricia H.; Abood, Mary E.; Croatt, Mitchell P.

    2017-01-01

    The first structure-activity relationships for a benzothiazole scaffold acting as an antagonist at GPR35 is presented. Analogues were designed based on a lead compound that was previously determined to have selective activity as a GPR35 antagonist. The synthetic route was modular in nature to independently explore the role of the middle and both ends of the scaffold. The activities of the analogues illustrate the importance of all three segments of the compound. PMID:27989666

  8. Synthetic and structure-activity relationship of insecticidal bufadienolides.

    PubMed

    Hidayat, Ace Tatang; Zainuddin, Achmad; Dono, Danar; Hermawan, Wawan; Hayashi, Hideo; Supratman, Unang

    2014-07-01

    A new synthetic analog of bufadienolide, methyl isobryophyllinate A (1), and a known synthetic analog, methyl isobersaldegenate-1,3,5-orthoacetate (2), were obtained by methanolysis of bryophyllin A (3) and bersaldegenin-1,3,5-orthoacetate (5) in basic solution. Structure-insecticidal activity relationship studies revealed both orthoacetate and alpha-pyrone moieties seemed to be essential structural elements for exhibiting insecticidal activity, whereas oxygenated substituents in the C ring enhanced the insecticidal activity against the third instar larvae of silkworm (Bombyx mori).

  9. Technical Consultation of the International Space Station (ISS) Internal Active Thermal Control System (IATCS) Cooling Water Chemistry

    NASA Technical Reports Server (NTRS)

    Gentz, Steven J.; Rotter, Hank A.; Easton, Myriam; Lince, Jeffrey; Park, Woonsup; Stewart, Thomas; Speckman, Donna; Dexter, Stephen; Kelly, Robert

    2005-01-01

    The Internal Active Thermal Control System (IATCS) coolant exhibited unexpected chemical changes during the first year of on-orbit operation following the launch and activation in February 2001. The coolant pH dropped from 9.3 to below the minimum specification limit of 9.0, and re-equilibrated between 8.3 and 8.5. This drop in coolant pH was shown to be the result of permeation of CO2 from the cabin into the coolant via Teflon flexible hoses which created carbonic acid in the fluid. This unexpected diffusion was the result of having a cabin CO2 partial pressure higher than the ground partial pressure (average 4.0 mmHg vs. less than 0.2 mmHg). This drop in pH was followed by a concurrent increasing coolant nickel concentration. No other metal ions were observed in the coolant and based on previous tests, the source of nickel ion was thought to be the boron nickel (BNi) braze intermetallics used in the construction of HXs and cold plates. Specifically, BNi2 braze alloy was used for the IATCS IFHX and BNi3 braze alloy was used for the IATCS Airlock Servicing and Performance Checkout Unit (SPCU) HX and cold plates. Given the failure criticality of the HXs, a Corrosion Team was established by the IATCS CWG to determine the impact of the nickel corrosion on hardware performance life.

  10. Turbopump thermodynamic cooling

    NASA Technical Reports Server (NTRS)

    Patten, T. C.; Mckee, H. B.

    1972-01-01

    System for cooling turbopumps used in cryogenic fluid storage facilities is described. Technique uses thermodynamic propellant vent to intercept pump heat at desired conditions. Cooling system uses hydrogen from outside source or residual hydrogen from cryogenic storage tank.

  11. Liquid cooled garments

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Liquid cooled garments employed in several applications in which severe heat is encountered are discussed. In particular, the use of the garments to replace air line cooling units in a variety of industrial processing situations is discussed.

  12. Metamaterial enhances natural cooling

    NASA Astrophysics Data System (ADS)

    2017-03-01

    A new metamaterial film that uses passive radiative cooling to dissipate heat from an object and provides cooling without a power input has been developed by a team at the University of Colorado Boulder in the US.

  13. Liquid-Cooled Garment

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A liquid-cooled bra, offshoot of Apollo moon suit technology, aids the cancer-detection technique known as infrared thermography. Water flowing through tubes in the bra cools the skin surface to improve resolution of thermograph image.

  14. DBAASP: database of antimicrobial activity and structure of peptides.

    PubMed

    Gogoladze, Giorgi; Grigolava, Maia; Vishnepolsky, Boris; Chubinidze, Mindia; Duroux, Patrice; Lefranc, Marie-Paule; Pirtskhalava, Malak

    2014-08-01

    The Database of Antimicrobial Activity and Structure of Peptides (DBAASP) is a manually curated database for those peptides for which antimicrobial activity against particular targets has been evaluated experimentally. The database is a depository of complete information on: the chemical structure of peptides; target species; target object of cell; peptide antimicrobial/haemolytic/cytotoxic activities; and experimental conditions at which activities were estimated. The DBAASP search page allows the user to search peptides according to their structural characteristics, complexity type (monomer, dimer and two-peptide), source, synthesis type (ribosomal, nonribosomal and synthetic) and target species. The database prediction algorithm provides a tool for rational design of new antimicrobial peptides. DBAASP is accessible at http://www.biomedicine.org.ge/dbaasp/.

  15. An Assessment of Physics Research Opportunities Available from Rapid Heating and Cooling.

    DTIC Science & Technology

    1980-04-07

    material properties such as amorphous structures, metastable crystalline structures , enhanced solid solubility, reduced chenical segregation, refined...and metastable crystalline structures by rapid cooling suggests that special metastable structures might be formed by rapid cooling techniques. There

  16. Bubble heating in Extreme Cooling Clusters

    NASA Astrophysics Data System (ADS)

    Allen, Steven

    2007-09-01

    Our proposal targets `extreme cooling' clusters: those systems with the largest, fastest cooling rates that most severely challenge the AGN-heating paradigm for cluster cores. By targeting two X-ray bright `extreme cooling cluters' with the clearest radio bubbles in their cores, we seek to establish whether it is possible for AGN heating to balance cooling in such systems. If cooling is not balanced by some heat source, then large residual cooling rates should be detectable in the spectral X-ray data. We will measure the bubble properties precisely and map the spatial-spectral structure of the surrounding X-ray gas, searching for ghost bubbles, shocks, ripples, fronts and non-thermal emission.

  17. Passive coolers for pre-cooling of JT loops for deep space infrared imaging applications

    NASA Astrophysics Data System (ADS)

    Zhang, Burt; Larson, Melora; Rodriguez, Jose

    2010-09-01

    Infrared instruments (IR) for deep space imaging missions, such as the James Webb Space Telescope (JWST) and Planck, require cryogenic cooling for proper operation of their focal plane arrays (FPA) in far infrared and sub-millimeter wavelength ranges. The FPA is sometimes located meters away from the spacecraft. To meet such remote cooling requirement, a Joule-Thomson (J-T) loop becomes a convenient choice for either direct cooling for the FPA or for serving as a heat sink for a cascade cooling system. The refrigerant lines of the JT loop inevitably suffer parasitic heat leak primarily due to IR backload as they traverse from the spacecraft to the FPA. An actively cooled JT loop using a mechanical pre-cooler located at the spacecraft will experience the highest parasitic heat leak since the lines are cold through the entire length whereas a passively cooled JT loop can utilize a number of radiators to cool the lines down gradually in stages and hence reduce the heat leak. In addition to savings in power and mass, a passive cooler offers consistent and predictable performance with practically no performance degradation in a thermally stable orbit, such as one around the Sun-Earth L2 point. Passive coolers are less popular in low temperature applications when their cooling capacity diminishes rapidly in proportion to T4 until the temperature reaches a point where either the parasitic heat leak becomes so significant or its size becomes so excessive that the passive cooling scheme becomes impractical. Despite the limited capacity, passive cooling may still prove to be a viable alternative to active cooling depending on the operating temperature and heat dissipation rate of the FPA. The current effort aims at evaluating the merit of using passive coolers as an alternative to using a mechanical cooler for pre-cooling of a JT loop for remote IR instrument cooling. A parametric study is conducted to explore the merits of passive cooling of a JT loop in a temperature range

  18. ASTROMAG coil cooling study

    NASA Technical Reports Server (NTRS)

    Maytal, Ben-Zion; Vansciver, Steven W.

    1990-01-01

    ASTROMAG is a planned particle astrophysics magnetic facility. Basically it is a large magnetic spectrometer outside the Earth's atmosphere for an extended period of time in orbit on a space station. A definition team summarized its scientific objectives assumably related to fundamental questions of astrophysics, cosmology, and elementary particle physics. Since magnetic induction of about 7 Tesla is desired, it is planned to be a superconducting magnet cooled to liquid helium 2 temperatures. The general structure of ASTROMAG is based on: (1) two superconducting magnetic coils, (2) dewar of liquid helium 2 to provide cooling capability for the magnets; (3) instrumentation, matter-anti matter spectrometer (MAS) and cosmic ray isotope spectrometer (CRIS); and (4) interfaces to the shuttle and space station. Many configurations of the superconducting magnets and the dewar were proposed and evaluated, since those are the heart of the ASTROMAG. Baseline of the magnet configuration and cryostat as presented in the phase A study and the one kept in mind while doing the present study are presented. ASTROMAG's development schedule reflects the plan of launching to the space station in 1995.

  19. Data center cooling system

    DOEpatents

    Chainer, Timothy J; Dang, Hien P; Parida, Pritish R; Schultz, Mark D; Sharma, Arun

    2015-03-17

    A data center cooling system may include heat transfer equipment to cool a liquid coolant without vapor compression refrigeration, and the liquid coolant is used on a liquid cooled information technology equipment rack housed in the data center. The system may also include a controller-apparatus to regulate the liquid coolant flow to the liquid cooled information technology equipment rack through a range of liquid coolant flow values based upon information technology equipment temperature thresholds.

  20. Anticancer Activity of Estradiol Derivatives: A Quantitative Structure--Activity Relationship Approach

    NASA Astrophysics Data System (ADS)

    Muranaka, Ken

    2001-10-01

    Commercial packages to implement modern QSAR (quantitative structure-activity relationship) techniques are highly priced; however, the essence of QSAR can be taught without them. Microsoft Excel was used to analyze published data on anticancer activities of estradiol analogs by a QSAR approach. The resulting QSAR equations highly correlate the structural features and physicochemical properties of the analogs with the observed biological activities by multiple linear regression.

  1. Effect of micro cooling channels on a hydrogen peroxide monopropellant microthruster performance

    NASA Astrophysics Data System (ADS)

    Huh, Jeongmoo; Kwon, Sejin

    2015-12-01

    In this paper, a hydrogen peroxide monopropellant microthrusters with and without regenerative micro cooling channels were fabricated and performance test results were compared to determine cooling effect of the regenerative micro cooling channels. Photosensitive glass was used as microfabrication material, which is cost-effective for MEMS fabrication process. Nine photosensitive glasses was integrated using UV and thermal bonding and composed the microthrusters. 90wt% hydrogen peroxide was used both as monopropellant and cooling fluid. For hydrogen peroxide decomposition, catalyst was fabricated and inserted into the microchamber. Platinum was used as the catalyst active material and γ-alumina was used as catalyst support. Experimental testing was conducted to determine effect of the cooling channels and the chamber pressure, temperature and surface temperature were measured. The performance test results showed that it was possible to relieve the thermal shock of the micro thruster structure by as much as 64% by adding regenerative micro cooling channels on both sides of the microthruster chamber. However, the chamber pressure and temperature decreased by regenerative cooling channels due to excessive cooling effects.

  2. Cooling of Stored Beams

    SciTech Connect

    Mills, F.

    1986-06-10

    Beam cooling methods developed for the accumulation of antiprotons are being employed to assist in the performance of experiments in Nuclear and Particle Physics with ion beams stored in storage rings. The physics of beam cooling, and the ranges of utility of stochastic and electron cooling are discussed in this paper.

  3. Stochastic cooling in RHIC

    SciTech Connect

    Brennan,J.M.; Blaskiewicz, M. M.; Severino, F.

    2009-05-04

    After the success of longitudinal stochastic cooling of bunched heavy ion beam in RHIC, transverse stochastic cooling in the vertical plane of Yellow ring was installed and is being commissioned with proton beam. This report presents the status of the effort and gives an estimate, based on simulation, of the RHIC luminosity with stochastic cooling in all planes.

  4. COMBINED ACTIVE/PASSIVE DECAY HEAT REMOVAL APPROACH FOR THE 24 MWt GAS-COOLED FAST REACTOR

    SciTech Connect

    CHENG,L.Y.; LUDEWIG, H.

    2007-06-01

    Decay heat removal at depressurized shutdown conditions has been regarded as one of the key areas where significant improvement in passive response was targeted for the GEN IV GFR over the GCFR designs of thirty years ago. It has been recognized that the poor heat transfer characteristics of gas coolant at lower pressures needed to be accommodated in the GEN IV design. The design envelope has therefore been extended to include a station blackout sequence simultaneous with a small break/leak. After an exploratory phase of scoping analysis in this project, together with CEA of France, it was decided that natural convection would be selected as the passive decay heat removal approach of preference. Furthermore, a double vessel/containment option, similar to the double vessel/guard vessel approach of the SFR, was selected as the means of design implementation to reduce the PRA risks of the depressurization accident. However additional calculations in conjunction with CEA showed that there was an economic penalty in terms of decay heat removal system heat exchanger size, elevation heights for thermal centers, and most of all in guard containment back pressure for complete reliance on natural convection only. The back pressure ranges complicated the design requirements for the guard containment. Recognizing that the definition of a loss-of-coolant-accident in the GFR is a misnomer, since gas coolant will always be present, and the availability of some driven blower would reduce fuel temperature transients significantly; it was decided instead to aim for a hybrid active/passive combination approach to the selected BDBA. Complete natural convection only would still be relied on for decay heat removal but only after the first twenty four hours after the initiation of the accident. During the first twenty four hour period an actively powered blower would be relied on to provide the emergency decay power removal. However the power requirements of the active blower

  5. COOL CORE CLUSTERS FROM COSMOLOGICAL SIMULATIONS

    SciTech Connect

    Rasia, E.; Borgani, S.; Murante, G.; Planelles, S.; Biffi, V.; Granato, G. L.; Beck, A. M.; Steinborn, L. K.; Dolag, K.; Ragone-Figueroa, C.

    2015-11-01

    We present results obtained from a set of cosmological hydrodynamic simulations of galaxy clusters, aimed at comparing predictions with observational data on the diversity between cool-core (CC) and non-cool-core (NCC) clusters. Our simulations include the effects of stellar and active galactic nucleus (AGN) feedback and are based on an improved version of the smoothed particle hydrodynamics code GADGET-3, which ameliorates gas mixing and better captures gas-dynamical instabilities by including a suitable artificial thermal diffusion. In this Letter, we focus our analysis on the entropy profiles, the primary diagnostic we used to classify the degree of cool-coreness of clusters, and the iron profiles. In keeping with observations, our simulated clusters display a variety of behaviors in entropy profiles: they range from steadily decreasing profiles at small radii, characteristic of CC systems, to nearly flat core isentropic profiles, characteristic of NCC systems. Using observational criteria to distinguish between the two classes of objects, we find that they occur in similar proportions in both simulations and observations. Furthermore, we also find that simulated CC clusters have profiles of iron abundance that are steeper than those of NCC clusters, which is also in agreement with observational results. We show that the capability of our simulations to generate a realistic CC structure in the cluster population is due to AGN feedback and artificial thermal diffusion: their combined action allows us to naturally distribute the energy extracted from super-massive black holes and to compensate for the radiative losses of low-entropy gas with short cooling time residing in the cluster core.

  6. Semi Active Control of Civil Structures, Analytical and Numerical Studies

    NASA Astrophysics Data System (ADS)

    Kerboua, M.; Benguediab, M.; Megnounif, A.; Benrahou, K. H.; Kaoulala, F.

    Structural control for civil structures was born out of a need to provide safer and more efficient designs with the reality of limited resources. The purpose of structural control is to absorb and to reflect the energy introduced by dynamic loads such as winds, waves, earthquakes, and traffic. Today, the protection of civil structures from severe dynamic loading is typically achieved by allowing the structures to be damaged. Semi-active control devices, also called "smart" control devices, assume the positive aspects of both the passive and active control devices. A semi-active control strategy is similar to the active control strategy. Only here, the control actuator does not directly apply force to the structure, but instead it is used to control the properties of a passive energy device, a controllable passive damper. Semi-active control strategies can be used in many of the same civil applications as passive and active control. One method of operating smart cable dampers is in a purely passive capacity, supplying the dampers with constant optimal voltage. The advantages to this strategy are the relative simplicity of implementing the control strategy as compared to a smart or active control strategy and that the dampers are more easily optimally tuned in- place, eliminating the need to have passive dampers with unique optimal damping coefficients. This research investigated semi-active control of civil structures for natural hazard mitigation. The research has two components, the seismic protection of buildings and the mitigation of wind-induced vibration in structures. An ideal semi-active motion equation of a composite beam that consists of a cantilever beam bonded with a PZT patch using Hamilton's principle and Galerkin's method was treated. A series R-L and a parallel R-L shunt circuits are coupled into the motion equation respectively by means of the constitutive relation of piezoelectric material and Kirchhoff's law to control the beam vibration. A

  7. Structure and Mechanism of the Phosphotyrosyl Phosphatase Activator

    SciTech Connect

    Chao,Y.; Xing, Y.; Chen, Y.; Xu, Y.; Lin, Z.; Li, Z.; Jeffrey, P.; Stock, J.; Shi, Y.

    2006-01-01

    Phosphotyrosyl phosphatase activator (PTPA), also known as PP2A phosphatase activator, is a conserved protein from yeast to human. Here we report the 1.9 {angstrom} crystal structure of human PTPA, which reveals a previously unreported fold consisting of three subdomains: core, lid, and linker. Structural analysis uncovers a highly conserved surface patch, which borders the three subdomains, and an associated deep pocket located between the core and the linker subdomains. The conserved surface patch and the deep pocket are responsible for binding to PP2A and ATP, respectively. PTPA and PP2A A-C dimer together constitute a composite ATPase. PTPA binding to PP2A results in a dramatic alteration of substrate specificity, with enhanced phosphotyrosine phosphatase activity and decreased phosphoserine phosphatase activity. This function of PTPA strictly depends on the composite ATPase activity. These observations reveal significant insights into the function and mechanism of PTPA and have important ramifications for understanding PP2A function.

  8. Quantitative Structure-Antifungal Activity Relationships for cinnamate derivatives.

    PubMed

    Saavedra, Laura M; Ruiz, Diego; Romanelli, Gustavo P; Duchowicz, Pablo R

    2015-12-01

    Quantitative Structure-Activity Relationships (QSAR) are established with the aim of analyzing the fungicidal activities of a set of 27 active cinnamate derivatives. The exploration of more than a thousand of constitutional, topological, geometrical and electronic molecular descriptors, which are calculated with Dragon software, leads to predictions of the growth inhibition on Pythium sp and Corticium rolfsii fungi species, in close agreement to the experimental values extracted from the literature. A set containing 21 new structurally related cinnamate compounds is prepared. The developed QSAR models are applied to predict the unknown fungicidal activity of this set, showing that cinnamates like 38, 28 and 42 are expected to be highly active for Pythium sp, while this is also predicted for 28 and 34 in C. rolfsii.

  9. Structural basis of AMPK regulation by small molecule activators

    NASA Astrophysics Data System (ADS)

    Xiao, Bing; Sanders, Matthew J.; Carmena, David; Bright, Nicola J.; Haire, Lesley F.; Underwood, Elizabeth; Patel, Bhakti R.; Heath, Richard B.; Walker, Philip A.; Hallen, Stefan; Giordanetto, Fabrizio; Martin, Stephen R.; Carling, David; Gamblin, Steven J.

    2013-12-01

    AMP-activated protein kinase (AMPK) plays a major role in regulating cellular energy balance by sensing and responding to increases in AMP/ADP concentration relative to ATP. Binding of AMP causes allosteric activation of the enzyme and binding of either AMP or ADP promotes and maintains the phosphorylation of threonine 172 within the activation loop of the kinase. AMPK has attracted widespread interest as a potential therapeutic target for metabolic diseases including type 2 diabetes and, more recently, cancer. A number of direct AMPK activators have been reported as having beneficial effects in treating metabolic diseases, but there has been no structural basis for activator binding to AMPK. Here we present the crystal structure of human AMPK in complex with a small molecule activator that binds at a site between the kinase domain and the carbohydrate-binding module, stabilising the interaction between these two components. The nature of the activator-binding pocket suggests the involvement of an additional, as yet unidentified, metabolite in the physiological regulation of AMPK. Importantly, the structure offers new opportunities for the design of small molecule activators of AMPK for treatment of metabolic disorders.

  10. Active Piezoelectric Structures for Tip Clearance Management Assessed

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Managing blade tip clearance in turbomachinery stages is critical to developing advanced subsonic propulsion systems. Active casing structures with embedded piezoelectric actuators appear to be a promising solution. They can control static and dynamic tip clearance, compensate for uneven deflections, and accomplish electromechanical coupling at the material level. In addition, they have a compact design. To assess the feasibility of this concept and assist the development of these novel structures, the NASA Lewis Research Center developed in-house computational capabilities for composite structures with piezoelectric actuators and sensors, and subsequently used them to simulate candidate active casing structures. The simulations indicated the potential of active casings to modify the blade tip clearance enough to improve stage efficiency. They also provided valuable design information, such as preliminary actuator configurations (number and location) and the corresponding voltage patterns required to compensate for uneven casing deformations. An active ovalization of a casing with four discrete piezoceramic actuators attached on the outer surface is shown. The center figure shows the predicted radial displacements along the hoop direction that are induced when electrostatic voltage is applied at the piezoceramic actuators. This work, which has demonstrated the capabilities of in-house computational models to analyze and design active casing structures, is expected to contribute toward the development of advanced subsonic engines.

  11. Informational Complexity and Functional Activity of RNA Structures

    PubMed Central

    Carothers, James M.; Oestreich, Stephanie C.; Davis, Jonathan H.

    2004-01-01

    Very little is known about the distribution of functional DNA, RNA, and protein molecules in sequence space. The question of how the number and complexity of distinct solutions to a particular biochemical problem varies with activity is an important aspect of this general problem. Here we present a comparison of the structures and activities of eleven distinct GTP-binding RNAs (aptamers). By experimentally measuring the amount of information required to specify each optimal binding structure, we show that defining a structure capable of 10-fold tighter binding requires approximately 10 additional bits of information. This increase in information content is equivalent to specifying the identity of five additional nucleotide positions and corresponds to an ∼1000-fold decrease in abundance in a sample of random sequences. We observe a similar relationship between structural complexity and activity in a comparison of two catalytic RNAs (ribozyme ligases), raising the possibility of a general relationship between the complexity of RNA structures and their functional activity. Describing how information varies with activity in other heteropolymers, both biological and synthetic, may lead to an objective means of comparing their functional properties. This approach could be useful in predicting the functional utility of novel heteropolymers. PMID:15099096

  12. Slow cooling of protein crystals.

    PubMed

    Warkentin, Matthew; Thorne, Robert E

    2009-10-01

    Cryoprotectant-free thaumatin crystals have been cooled from 300 to 100 K at a rate of 0.1 K s(-1) - 10(3)-10(4) times slower than in conventional flash cooling - while continuously collecting X-ray diffraction data, so as to follow the evolution of protein lattice and solvent properties during cooling. Diffraction patterns show no evidence of crystalline ice at any temperature. This indicates that the lattice of protein molecules is itself an excellent cryoprotectant, and with sodium potassium tartrate incorporated from the 1.5 M mother liquor ice nucleation rates are at least as low as in a 70% glycerol solution. Crystal quality during slow cooling remains high, with an average mosaicity at 100 K of 0.2 degrees . Most of the mosaicity increase occurs above approximately 200 K, where the solvent is still liquid, and is concurrent with an anisotropic contraction of the unit cell. Near 180 K a crossover to solid-like solvent behavior occurs, and on further cooling there is no additional degradation of crystal order. The variation of B factor with temperature shows clear evidence of a protein dynamical transition near 210 K, and at lower temperatures the slope dB/dT is a factor of 3-6 smaller than has been reported for any other protein. These results establish the feasibility of fully temperature controlled studies of protein structure and dynamics between 300 and 100 K.

  13. Cooling Technology for Large Space Telescopes

    NASA Technical Reports Server (NTRS)

    DiPirro, Michael; Cleveland, Paul; Durand, Dale; Klavins, Andy; Muheim, Daniella; Paine, Christopher; Petach, Mike; Tenerelli, Domenick; Tolomeo, Jason; Walyus, Keith

    2007-01-01

    NASA's New Millennium Program funded an effort to develop a system cooling technology, which is applicable to all future infrared, sub-millimeter and millimeter cryogenic space telescopes. In particular, this technology is necessary for the proposed large space telescope Single Aperture Far-Infrared Telescope (SAFIR) mission. This technology will also enhance the performance and lower the risk and cost for other cryogenic missions. The new paradigm for cooling to low temperatures will involve passive cooling using lightweight deployable membranes that serve both as sunshields and V-groove radiators, in combination with active cooling using mechanical coolers operating down to 4 K. The Cooling Technology for Large Space Telescopes (LST) mission planned to develop and demonstrate a multi-layered sunshield, which is actively cooled by a multi-stage mechanical cryocooler, and further the models and analyses critical to scaling to future missions. The outer four layers of the sunshield cool passively by radiation, while the innermost layer is actively cooled to enable the sunshield to decrease the incident solar irradiance by a factor of more than one million. The cryocooler cools the inner layer of the sunshield to 20 K, and provides cooling to 6 K at a telescope mounting plate. The technology readiness level (TRL) of 7 will be achieved by the active cooling technology following the technology validation flight in Low Earth Orbit. In accordance with the New Millennium charter, tests and modeling are tightly integrated to advance the technology and the flight design for "ST-class" missions. Commercial off-the-shelf engineering analysis products are used to develop validated modeling capabilities to allow the techniques and results from LST to apply to a wide variety of future missions. The LST mission plans to "rewrite the book" on cryo-thermal testing and modeling techniques, and validate modeling techniques to scale to future space telescopes such as SAFIR.

  14. Cooling water distribution system

    DOEpatents

    Orr, Richard

    1994-01-01

    A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using an interconnected series of radial guide elements, a plurality of circumferential collector elements and collector boxes to collect and feed the cooling water into distribution channels extending along the curved surface of the steel containment vessel. The cooling water is uniformly distributed over the curved surface by a plurality of weirs in the distribution channels.

  15. Active structural acoustic control using the remote sensor method

    NASA Astrophysics Data System (ADS)

    Cheer, Jordan; Daley, Steve

    2016-09-01

    Active structural acoustic control (ASAC) is an effective method of reducing the sound radiation from vibrating structures. In order to implement ASAC systems using only structural actuators and sensors, it is necessary to employ a model of the sound radiation from the structure. Such models have been presented in the literature for simple structures, such as baffled rectangular plates, and methods of determining the radiation modes of more complex practical structures using experimental data have also been explored. A similar problem arises in the context of active noise control, where cancellation of a disturbance is required at positions in space where it is not possible to locate a physical error microphone. In this case the signals at the cancellation points can be estimated from the outputs of remotely located measurement sensors using the “remote microphone method”. This remote microphone method is extended here to the ASAC problem, in which the pressures at a number of microphone locations must be estimated from measurements on the structure of the radiating system. The control and estimation strategies are described and the performance is assessed for a typical structural radiation problem.

  16. Database of Active Structures From the Indo-Asian Collision

    NASA Astrophysics Data System (ADS)

    Styron, Richard; Taylor, Michael; Okoronkwo, Kelechi

    2010-05-01

    The ongoing collision of India and Asia has produced a vast system of folds and faults, many of which are active today, as evidenced by such recent deadly earthquakes as the 12 May 2008 Sichuan quake [Parsons et al., 2008]. Understanding these events requires knowledge of the region’s geologic structures. Taylor and Yin [2009] have assembled HimaTibetMap-1.0, a multiformat, comprehensive database of first-order active structures in central Asia that may aid researchers, educators, and students in their studies of Indo-Asian tectonics. For example, this database may be used by seismologists, geodesists, and modelers to identify structures in particular locations that contribute to active deformation, or it may be used by teachers to illustrate concepts such as continental collision or distributed deformation of continents.

  17. Structure-molluscicidal activity relationships of acylphloroglucinols from ferns.

    PubMed

    Socolsky, Cecilia; Borkosky, Susana; Bardón, Alicia

    2011-03-01

    The molluscicidal activity of 12 phloroglucinol derivatives previously isolated from Elaphoglossum piloselloides, E. gayanum, E. yungense, and E. lindbergii, as well as 3 known acylphloroglucinols, now reported from an Argentine collection of Dryopteris wallichiana, was evaluated against the schistosomiasis vector snail Biomphalaria peregrina. Molluscicidal effects were analyzed and compared with those previously observed for 4 acylphloroglucinols from E. piloselloides and their corresponding peracetylated derivatives, in order to draw structure-activity relationships. The most active compounds were the prenylated desaspidins elaphogayanin B and elaphopilosins A and B (LD50 = 1.90, 2.90, and 0.94 ppm, respectively), together with the only evaluated prenylated para-aspidin, elaphopilosin C (LD50 = 2.15 ppm). Quantitative structure-activity relationships (QSAR) were studied by means of a semiempirical method (PM3) for the 24 natural phloroglucinol derivatives included in this paper. The descriptor molecular volume was found to have good correlation with the observed molluscicidal activity (r2 = 0.77). The derived equation can be considered useful to predict the molluscicidal activity of bi and tricyclic acylphloroglucinols. The QSAR analysis showed that there is an optimum volume for high activity, probably related to the size of a receptor's active site. Bigger molecules display lower activity.

  18. Personal cooling in hot workings

    SciTech Connect

    Tuck, M.A.

    1999-07-01

    The number of mines experiencing climatic difficulties worldwide is increasing. In a large number of cases these climatic difficulties are confined to working areas only or to specific locations within working areas. Thus the problem in these mines can be described as highly localized, due to a large extent not to high rock temperatures but due to machine heat loads and low airflow rates. Under such situations conventional means of controlling the climate can be inapplicable and/or uneconomic. One possible means of achieving the required level of climatic control, to ensure worker health and safety whilst achieving economic gains, is to adopt a system of active man cooling. This is the reverse of normal control techniques where the cooling power of the ventilating air is enhanced in some way. Current methods of active man cooling include ice jackets and various umbilical cord type systems. These have numerous drawbacks, such as limited useful exposure times and limitations to worker mobility. The paper suggests an alternative method of active man cooling than those currently available and reviews the design criteria for such a garment. The range of application of such a garment is discussed, under both normal and emergency situations.

  19. Aspartate and glutamate mimetic structures in biologically active compounds.

    PubMed

    Stefanic, Peter; Dolenc, Marija Sollner

    2004-04-01

    Glutamate and aspartate are frequently recognized as key structural elements for the biological activity of natural peptides and synthetic compounds. The acidic side-chain functionality of both the amino acids provides the basis for the ionic interaction and subsequent molecular recognition by specific receptor sites that results in the regulation of physiological or pathophysiological processes in the organism. In the development of new biologically active compounds that possess the ability to modulate these processes, compounds offering the same type of interactions are being designed. Thus, using a peptidomimetic design approach, glutamate and aspartate mimetics are incorporated into the structure of final biologically active compounds. This review covers different bioisosteric replacements of carboxylic acid alone, as well as mimetics of the whole amino acid structure. Amino acid analogs presented include those with different distances between anionic moieties, and analogs with additional functional groups that result in conformational restriction or alternative interaction sites. The article also provides an overview of different cyclic structures, including various cycloalkane, bicyclic and heterocyclic analogs, that lead to conformational restriction. Higher di- and tripeptide mimetics in which carboxylic acid functionality is incorporated into larger molecules are also reviewed. In addition to the mimetic structures presented, emphasis in this article is placed on their steric and electronic properties. These mimetics constitute a useful pool of fragments in the design of new biologically active compounds, particularly in the field of RGD mimetics and excitatory amino acid agonists and antagonists.

  20. Interplanetary planar magnetic structures associated with expanding active regions

    NASA Technical Reports Server (NTRS)

    Nakagawa, Tomoko; Uchida, Yutaka

    1995-01-01

    Planar magnetic structures are interplanetary objects whose magnetic field cannot be explained by Parker's solar wind model. They are characterized by two-dimensional structure of magnetic field that are highly variable and parallel to a plane which is inclined to the ecliptic plane. They appeared independently of interplanetary compression, solar flares, active prominences nor filament disappearances, but the sources often coincided with active regions. On the other hand, it has been discovered by the Yohkoh Soft X-ray telescope that active-region corona expand outwards at speeds of a few to a few tens of km/s near the Sun. The expansions occurred repeatedly, almost continually, even in the absence of any sizable flares. In the Yohkoh Soft X-ray images, the active-region corona seems to expand out into interplanetary space. Solar sources of interplanetary planar magnetic structures observed by Sakigake were examined by Yohkoh soft X-ray telescope. During a quiet period of the Sun from January 6 to November 11, 1993, there found 5 planar magnetic structures according to the criteria (absolute value of Bn)/(absolute value of B) less than 0.1 for planarity and (dB)/(absolute value of B) greater than 0.7 for variability of magnetic field, where Bn, dB, and the absolute value of B are field component normal to a plane, standard deviation, and average of the magnitude of the magnetic field, respectively. Sources of 4 events were on low-latitude (less than 5 degrees) active regions from which loop-like structures were expanding. The coincidence, 80%, is extremely high with respect to accidental coincidence, 7%, of Sakigake windows of solar wind observation with active regions. The last source was on loop-like features which seemed to be related with a mid-latitude (20 degrees) active region.

  1. Synthesis, Fungicidal Activity, and Structure Activity Relationship of β-Acylaminocycloalkylsulfonamides against Botrytis cinerea

    PubMed Central

    Liu, Chun-Hui; Chen, Xiao-Yuan; Qin, Pei-Wen; Qi, Zhi-Qiu; Ji, Ming-Shan; Liu, Xing-Yu; Babu, P. Vijaya; Li, Xing-Hai; Cui, Zi-Ning

    2017-01-01

    In order to discover new antifungal agrochemicals that could have highly active and novel motifs, thirty-six new 2-acylaminocycloalkylsulfonamides (IV) were synthesized. Their structures were characterized and confirmed by 1H NMR, 13C NMR, IR, MS, elemental analysis and X-ray single crystal diffraction. In vitro and in vivo activities against various Botrytis cinerea strains were evaluated. Bioassay results revealed that most of the title compounds exhibited excellent in vitro fungicidal activity, in which compound IV-26 showed the highest activity against sensitive, low-resistant, moderate-resistant and high-resistant strains of B. cinerea compared with the positive fungicide procymidone. Meanwhile in vivo fungicidal activity of compound IV-31 was better than the commercial fungicides procymidone and chesulfamide in greenhouse trial. The structure activity relationship (SAR) was also discussed and the results were of importance to the structural optimization and development of more potent sulfonamides antifungal agents. PMID:28176837

  2. Impact of active controls technology on structural integrity

    NASA Technical Reports Server (NTRS)

    Noll, Thomas; Austin, Edward; Donley, Shawn; Graham, George; Harris, Terry

    1991-01-01

    This paper summarizes the findings of The Technical Cooperation Program to assess the impact of active controls technology on the structural integrity of aeronautical vehicles and to evaluate the present state-of-the-art for predicting the loads caused by a flight-control system modification and the resulting change in the fatigue life of the flight vehicle. The potential for active controls to adversely affect structural integrity is described, and load predictions obtained using two state-of-the-art analytical methods are given.

  3. Active stabilization of thin-wall structures under compressive loading

    NASA Astrophysics Data System (ADS)

    Welham, Jared; Calius, Emilio P.; Chase, J. Geoffrey

    2003-08-01

    The active suppression of elastic buckling instability has the potential to significantly increase the effective strength of thin-wall structures. Despite all the interest in smart structures, the active suppression of buckling has received comparatively little attention. This paper addresses the effects of embedded actuation on the compression buckling strength of laminated composite plates through analysis and simulation. Numerical models are formulated that include the influence of essential features such as sensor uncertainty and noise, actuator saturation and control architecture on the buckling process. Silicon-based strain sensors and diffuse laser distance sensors are both considered for use in the detection of incipient buckling behavior due to their increased sensitivity. Actuation is provided by paired distributions of piezo-electric material incorporated into both sides of the laminate. Optimal controllers are designed to command the structure to deform in ways that interfere with the development of buckling mode shapes. Commercial software packages are used to solve the resulting non-linear equations, and some of the tradeoffs are enumerated. Overall, the results show that active buckling control can considerably enhance resistance to instability under compressive loads. These buckling load predictions demonstrate the viability of optimal control and piezo-electric actuation for implementing active buckling control. Due to the importance of early detection, the relative effectiveness of active buckling control is shown to be strongly dependent on the performance of the sensing scheme, as well as on the characteristics of the structure.

  4. Structural Model of Active Bax at the Membrane

    PubMed Central

    Bleicken, Stephanie; Jeschke, Gunnar; Stegmueller, Carolin; Salvador-Gallego, Raquel; García-Sáez, Ana J.; Bordignon, Enrica

    2016-01-01

    Bax plays a central role in the mitochondrial pathway of apoptosis. Upon activation, cytosolic Bax monomers oligomerize on the surface of mitochondria and change conformation concertedly to punch holes into the outer membrane. The subsequent release of cytochrome c initiates cell death. However, the structure of membrane-inserted Bax and its mechanism of action remain largely unknown. Here, we propose a 3D model of active Bax at the membrane based on double electron-electron resonance (DEER) spectroscopy in liposomes and isolated mitochondria. We show that active Bax is organized at the membrane as assemblies of dimers. In addition to a stable dimerization domain, each monomer contains a more flexible piercing domain involved in interdimer interactions and pore formation. The most important structural change during Bax activation is the opening of the hairpin formed by helices 5 and 6, which adopts a clamp-like conformation central to the mechanism of mitochondrial permeabilization. PMID:25458844

  5. A near atomic structure of the active human apoptosome.

    PubMed

    Cheng, Tat Cheung; Hong, Chuan; Akey, Ildikó V; Yuan, Shujun; Akey, Christopher W

    2016-10-04

    In response to cell death signals, an active apoptosome is assembled from Apaf-1 and procaspase-9 (pc-9). Here we report a near atomic structure of the active human apoptosome determined by cryo-electron microscopy. The resulting model gives insights into cytochrome c binding, nucleotide exchange and conformational changes that drive assembly. During activation an acentric disk is formed on the central hub of the apoptosome. This disk contains four Apaf-1/pc-9 CARD pairs arranged in a shallow spiral with the fourth pc-9 CARD at lower occupancy. On average, Apaf-1 CARDs recruit 3 to 5 pc-9 molecules to the apoptosome and one catalytic domain may be parked on the hub, when an odd number of zymogens are bound. This suggests a stoichiometry of one or at most, two pc-9 dimers per active apoptosome. Thus, our structure provides a molecular framework to understand the role of the apoptosome in programmed cell death and disease.

  6. Structural complexities in the active layers of organic electronics.

    PubMed

    Lee, Stephanie S; Loo, Yueh-Lin

    2010-01-01

    The field of organic electronics has progressed rapidly in recent years. However, understanding the direct structure-function relationships between the morphology in electrically active layers and the performance of devices composed of these materials has proven difficult. The morphology of active layers in organic electronics is inherently complex, with heterogeneities existing across multiple length scales, from subnanometer to micron and millimeter range. A major challenge still facing the organic electronics community is understanding how the morphology across all of the length scales in active layers collectively determines the device performance of organic electronics. In this review we highlight experiments that have contributed to the elucidation of structure-function relationships in organic electronics and also point to areas in which knowledge of such relationships is still lacking. Such knowledge will lead to the ability to select active materials on the basis of their inherent properties for the fabrication of devices with prespecified characteristics.

  7. Glycyl radical activating enzymes: structure, mechanism, and substrate interactions.

    PubMed

    Shisler, Krista A; Broderick, Joan B

    2014-03-15

    The glycyl radical enzyme activating enzymes (GRE-AEs) are a group of enzymes that belong to the radical S-adenosylmethionine (SAM) superfamily and utilize a [4Fe-4S] cluster and SAM to catalyze H-atom abstraction from their substrate proteins. GRE-AEs activate homodimeric proteins known as glycyl radical enzymes (GREs) through the production of a glycyl radical. After activation, these GREs catalyze diverse reactions through the production of their own substrate radicals. The GRE-AE pyruvate formate lyase activating enzyme (PFL-AE) is extensively characterized and has provided insights into the active site structure of radical SAM enzymes including GRE-AEs, illustrating the nature of the interactions with their corresponding substrate GREs and external electron donors. This review will highlight research on PFL-AE and will also discuss a few GREs and their respective activating enzymes.

  8. Structure-Activity Relationship of Fluoroquinolones Against K. pneumoniae

    NASA Astrophysics Data System (ADS)

    Li, Xiao-hong; Zhang, Rui-zhou; Cheng, Xin-lu; Yang, Xiang-dong

    2007-04-01

    The structure-activity relationship of fluoroquinolones, which show anti-K. pneumoniae activity, was studied by using principal component analysis (PCA) and hierarchical cluster analysis (HCA). The PCA results showed that the lowest unoccupied molecular orbital energy, energy difference between the highest occupied and the lowest unoccupied molecular orbital, dipole moment, net atomic charge on atom I, molecular polarizability, partition coefficient and molecular refractivity of these compounds are responsible for the separation between high-activity and low-activity groups. The HCA results were similar to those obtained with PCA. By using the chemometric results, four synthetic compounds were analyzed through PCA and HCA, and three of them are proposed as active molecules against K. pneumoniae which is consistent with the results of clinical experiments. The methodologies of PCA and HCA provide a reliable rule for classifying new fluoroquinolones with anti-K. pneumoniae activity.

  9. Active rejection of persistent disturbances in flexible space structures

    NASA Technical Reports Server (NTRS)

    Hwang, Cheng-Neng; Jayasuriya, Suhada; Parlos, Alexander G.; Sunkel, John W.

    1990-01-01

    A dynamic compensator for active rejection of persistent disturbances in flexible space structures is designed on the principle of the H(infinity)-optimization of the sensitivity transfer function matrix. A general state space solution is formulated to the multiinput multioutput H(infinity)-optimal control problem, allowing the use of the H(infinity)-optimal synthesis algorithm for the state-space models of space structures that result from model order reduction. Disturbances encountered in flexible space structures, such as shuttle docking, are investigated using the high-mode and the reduced-order models of a cantilevered two-bay truss, demonstrating the applicability of the H(infinity)-optimal approach.

  10. Color-preserving daytime radiative cooling

    NASA Astrophysics Data System (ADS)

    Zhu, Linxiao; Raman, Aaswath; Fan, Shanhui

    2013-11-01

    We introduce a general approach to radiatively lower the temperature of a structure, while preserving its color under sunlight. The cooling effect persists in the presence of considerable convective and conductive heat exchange and for different solar absorptances.

  11. Color-preserving daytime radiative cooling

    SciTech Connect

    Zhu, Linxiao; Raman, Aaswath; Fan, Shanhui

    2013-11-25

    We introduce a general approach to radiatively lower the temperature of a structure, while preserving its color under sunlight. The cooling effect persists in the presence of considerable convective and conductive heat exchange and for different solar absorptances.

  12. Active vibration control of structures undergoing bending vibrations

    NASA Technical Reports Server (NTRS)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor)

    1995-01-01

    An active vibration control subassembly for a structure (such as a jet engine duct or a washing machine panel) undergoing bending vibrations caused by a source (such as the clothes agitator of the washing machine) independent of the subassembly. A piezoceramic actuator plate is vibratable by an applied electric AC signal. The plate is connected to the structure such that vibrations in the plate induced by the AC signal cause canceling bending vibrations in the structure and such that the plate is compressively pre-stressed along the structure when the structure is free of any bending vibrations. The compressive prestressing increases the amplitude of the canceling bending vibrations before the critical tensile stress level of the plate is reached. Preferably, a positive electric DC bias is also applied to the plate in its poling direction.

  13. [Structure and Activity of Fungal Lipases in Bile Salt Solutions].

    PubMed

    Bogdanova, L R; Bakirova, D R; Valiullina, Yu A; Idiyatullin, B Z; Faizullin, D A; Zueva, O S; Zuev, Yu F

    2016-01-01

    The changes in structure and catalytic properties of fungal lipases (Candida rugosa, Rhizomucor miehei, Mucor javanicus) were investigated in micellar solutions of bile salts that differ in hydrophilic-lypophilic balance and reaction medium properties. The methods of circular dichroism and tryptophan fluorescence were applied to estimate the changes in peptide structure within complexes with bile salt micelles. Bile salts do not exert a significant influence on the structure of the enzymes under study: in Rh. miehei and M. javanicus lipases the alpha helix content slightly decreased, the influence of bile salts on the C. rugosa structure was not revealed. Despite negligible structural modifications in the enzymes, in bile salt solutions a considerable change in their catalytic properties was observed: an abrupt decrease in catalytic effectiveness. Substrate-bile salts micelles complex formation was demonstrated by the NMR self-diffusion method. The model of a regulation of fungal lipase activity was proposed.

  14. Active disturbance rejection in large flexible space structures

    NASA Technical Reports Server (NTRS)

    Parlos, Alexander G.; Sunkel, John W.

    1990-01-01

    The design of an active control law for the rejection of persistent disturbances, in large space structures is presented. The control system design approach is based on a deterministic model of the disturbances and it optimizes the magnitude of the disturbance that the structure can tolerate without violating certain predetermined constraints. In addition to closed-loop stability, the explicit treatment of state, control, and control rate constraints, such as structural displacement and control actuator effort, guarantees that the final design will exhibit desired performance characteristics. The technique is applied to a simple two-bay truss structure, and its response is compared with that obtained using a linear-quadratic-Gaussian/loop-transfer-recovery (LQG/LTR) compensator. Preliminary results indicate that the proposed control system can reject persistent disturbances of greater magnitude by utilizing most of the available control, while limiting the structural displacements to within desired tolerances.

  15. Structural and mechanistic insights into Mps1 kinase activation

    SciTech Connect

    Wang, Wei; Yang, Yuting; Gao, Yuefeng; Xu, Quanbin; Wang, Feng; Zhu, Songcheng; Old, William; Resing, Katheryn; Ahn, Natalie; Lei, Ming; Liu, Xuedong

    2010-11-05

    Mps1 is one of the several essential kinases whose activation is required for robust mitotic spindle checkpoint signalling. The activity of Mps1 is tightly regulated and increases dramatically during mitosis or in response to spindle damage. To understand the molecular mechanism underlying Mps1 regulation, we determined the crystal structure of the kinase domain of Mps1. The 2.7-{angstrom}-resolution crystal structure shows that the Mps1 kinase domain adopts a unique inactive conformation. Intramolecular interactions between the key Glu residue in the {alpha}C helix of the N-terminal lobe and the backbone amides in the catalytic loop lock the kinase in the inactive conformation. Autophosphorylation appears to be a priming event for kinase activation. We identified Mps1 autophosphorylation sites in the activation and the P+1 loops. Whereas activation loop autophosphorylation enhances kinase activity, autophosphorylation at the P+1 loop (T686) is associated with the active kinase. Mutation of T686 autophosphorylation site impairs both autophosphorylation and transphosphorylation. Furthermore, we demonstrated that phosphorylation of T676 may be a priming event for phosphorylation at T686. Finally, we identified two critical lysine residues in the loop between helices {alpha}EF and {alpha}F that are essential for substrate recruitment and maintaining high levels of kinase activity. Our studies reveal critical biochemical mechanisms for Mps1 kinase regulation.

  16. The Cool Flames Experiment

    NASA Technical Reports Server (NTRS)

    Pearlman, Howard; Chapek, Richard; Neville, Donna; Sheredy, William; Wu, Ming-Shin; Tornabene, Robert

    2001-01-01

    volume ratio, and (T(bar) - Tw ) is the spatially averaged temperature excess. This Newtonian form has been validated in spatially-uniform, well-stirred reactors, provided the effective heat transfer coefficient associated with the unsteady process is properly evaluated. Unfortunately, it is not a valid assumption for spatially-nonuniform temperature distributions induced by natural convection in unstirred reactors. "This is why the analysis of such a system is so difficult." Historically, the complexities associated with natural convection were perhaps recognized as early as 1938 when thermal ignition theory was first developed. In the 1955 text "Diffusion and Heat Exchange in Chemical Kinetics", Frank-Kamenetskii recognized that "the purely conductive theory can be applied at sufficiently low pressure and small dimensions of the vessel when the influence of natural convection can be disregarded." This was reiterated by Tyler in 1966 and further emphasized by Barnard and Harwood in 1974. Specifically, they state: "It is generally assumed that heat losses are purely conductive. While this may be valid for certain low pressure slow combustion regimes, it is unlikely to be true for the cool flame and ignition regimes." While this statement is true for terrestrial experiments, the purely conductive heat transport assumption is valid at microgravity (mu-g). Specifically, buoyant complexities are suppressed at mu-g and the reaction-diffusion structure associated with low temperature oxidation reactions, cool flames and auto-ignitions can be studied. Without natural convection, the system is simpler, does not require determination of the effective heat transfer coefficient, and is a testbed for analytic and numerical models that assume pure diffusive transport. In addition, mu-g experiments will provide baseline data that will improve our understanding of the effects of natural convection on Earth.

  17. Structural study of lysozyme in two ionic liquids at cryogenic temperature

    NASA Astrophysics Data System (ADS)

    Yoshimura, Yukihiro; Takekiyo, Takahiro; Mori, Takahiro

    2016-11-01

    We have investigated the structure and activity of chicken egg-white lysozyme in aqueous solutions of two typical ionic liquids, 1-butyl-3-methylimidazolium chloride and ethylammonium nitrate, at cryogenic temperature. An increase in structural disorder due to the unfolding and a decrease in the α-helical structure of lysozyme were noticeable upon glass formation. However, a decrease in the structural stability after cooling was less than that before cooling. The secondary and tertiary structures showed good reversibility upon cooling to 77 K and then reverting back to ambient temperature. We discussed an influence of a cooling upon the structure in aqueous ionic liquid solutions.

  18. Structural identification and cardiovascular activities of oxidized phospholipids.

    PubMed

    Salomon, Robert G

    2012-09-14

    Free radical-induced oxidation of membrane phospholipids generates complex mixtures of oxidized phospholipids (oxPLs). The combinatorial operation of a few dozen reaction types on a few dozen phospholipid structures results in the production of a dauntingly vast diversity of oxPL molecular species. Structural identification of the individual oxPL in these mixtures is a redoubtable challenge that is absolutely essential to allow determination of the biological activities of individual species. With an emphasis on cardiovascular consequences, this Review focuses on biological activities of oxPLs whose molecular structures are known and highlights 2 diametrically opposite approaches that were used to determine those structures, that is, (1) the classic approach from bioactivity of a complex mixture to isolation and structural characterization of the active molecule followed by confirmation of the structure by unambiguous chemical synthesis and (2) hypothesis of products that are likely to be generated by lipid oxidation, followed by synthesis, and then detection in vivo guided by the availability of authentic standards, and last, characterization of biological activities. Especially important for the application of the second paradigm is the capability of LC-MS/MS and derivatizations to selectively detect and quantify specific oxPL in complex mixtures, without the need for their isolation or complete separation. This technology can provide strong evidence for identity by comparisons with pure, well-characterized samples available by chemical syntheses. Those pure samples are critical for determining the biological activities attributable to specific molecular species of oxPLs in the complex mixtures generated in vivo as a consequence of oxidative stress.

  19. The Fe2(+)-Mg interdiffusion in orthopyroxene: Constraints from cation ordering and structural data and implications for cooling rates of meteorites

    NASA Technical Reports Server (NTRS)

    Ganguly, J.; Tazzoli, V.

    1993-01-01

    Orthopyroxene crystals in a number of meteorites exhibit compositional zoning of Fe and Mg, which provide important constraint on their cooling rates. However, attempts to model cooling rate of these crystals from Fe-Mg zoning profiles suffer from the lack of any measured or theoretically well constrained Fe-Mg interdiffusion data in OP(x) It has been assumed that Fe-Mg interdiffusion in OP(x) only slightly slower than that in olivine. The purpose of this paper is to (1) calculate the Fe-Mg fractionation, and (2) provide analytical formulation relating cooling rate to the length of the diffusion zone across the interface of the overgrowth of a mineral on itself with application to Mg diffusion profile across OP(x) growth on OP(x) in certain mesosiderites.

  20. Stochastic cooling in RHIC

    SciTech Connect

    Brennan J. M.; Blaskiewicz, M.; Mernick, K.

    2012-05-20

    The full 6-dimensional [x,x'; y,y'; z,z'] stochastic cooling system for RHIC was completed and operational for the FY12 Uranium-Uranium collider run. Cooling enhances the integrated luminosity of the Uranium collisions by a factor of 5, primarily by reducing the transverse emittances but also by cooling in the longitudinal plane to preserve the bunch length. The components have been deployed incrementally over the past several runs, beginning with longitudinal cooling, then cooling in the vertical planes but multiplexed between the Yellow and Blue rings, next cooling both rings simultaneously in vertical (the horizontal plane was cooled by betatron coupling), and now simultaneous horizontal cooling has been commissioned. The system operated between 5 and 9 GHz and with 3 x 10{sup 8} Uranium ions per bunch and produces a cooling half-time of approximately 20 minutes. The ultimate emittance is determined by the balance between cooling and emittance growth from Intra-Beam Scattering. Specific details of the apparatus and mathematical techniques for calculating its performance have been published elsewhere. Here we report on: the method of operation, results with beam, and comparison of results to simulations.