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Sample records for air revitalization loop

  1. Integrated Evaluation of Closed Loop Air Revitalization System Components

    NASA Technical Reports Server (NTRS)

    Murdock, K.

    2010-01-01

    NASA s vision and mission statements include an emphasis on human exploration of space, which requires environmental control and life support technologies. This Contractor Report (CR) describes the development and evaluation of an Air Revitalization System, modeling and simulation of the components, and integrated hardware testing with the goal of better understanding the inherent capabilities and limitations of this closed loop system. Major components integrated and tested included a 4-Bed Modular Sieve, Mechanical Compressor Engineering Development Unit, Temperature Swing Adsorption Compressor, and a Sabatier Engineering and Development Unit. The requisite methodolgy and technical results are contained in this CR.

  2. Air-Cooled Design of a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization Systems

    NASA Technical Reports Server (NTRS)

    Mulloth, Lila M.; Affleck, Dave L.; Rosen, Micha; LeVan, M. Douglas; Wang, Yuan; Cavalcante, Celio L.

    2004-01-01

    The air revitalization system of the International Space Station (ISS) operates in an open loop mode and relies on the resupply of oxygen and other consumables from earth for the life support of astronauts. A compressor is required for delivering the carbon dioxide from a removal assembly to a reduction unit to recover oxygen and thereby closing the air-loop. We have a developed a temperature-swing adsorption compressor (TSAC) for performing these tasks that is energy efficient, quiet, and has no rapidly moving parts. This paper discusses the mechanical design and the results of thermal model validation tests of a TSAC that uses air as the cooling medium.

  3. Closed-loop Habitation Air Revitalization Model for Regenerative Life Support Systems

    NASA Technical Reports Server (NTRS)

    Hart, Maxwell M.

    1991-01-01

    The primary function of any life support system is to keep the crew alive by providing breathable air, potable water, edible food, and for disposal of waste. In a well-balanced or regenerative life support system, the various components are each using what is available and producing what is needed by other components so that there will always be enough chemicals in the form in which they are needed. Humans are not just users, but also one of the participating parts of the system. If a system could continuously recycle the original chemicals, this would make it virtually a Closed-loop Habitation (CH). Some difficulties in trying to create a miniature version of a CH are briefly discussed. In a miniature CH, a minimal structure must be provided and the difference must be made up by artificial parts such as physicochemical systems that perform the conversions that the Earth can achieve naturally. To study the interactions of these parts, a computer model was designed that simulates a miniature CH with emphasis on the air revitalization part. It is called the Closed-loop Habitation Air Revitalization Model (CHARM).

  4. Development and Testing of a Temperature-swing Adsorption Compressor for Carbon Dioxide in Closed-loop Air Revitalization Systems

    NASA Technical Reports Server (NTRS)

    Mulloth, Lila M.; Rosen, Micha; Affleck, David; LeVan, M. Douglas; Wang, Yuan

    2005-01-01

    The air revitalization system of the International Space Station (ISS) operates in an open loop mode and relies on the resupply of oxygen and other consumables from earth for the life support of astronauts. A compressor is required for delivering the carbon dioxide from a removal assembly to a reduction unit to recover oxygen and thereby dosing the air-loop. We have developed a temperature-swing adsorption compressor (TSAC) that is energy efficient, quiet, and has no rapidly moving parts for performing these tasks. The TSAC is a solid-state compressor that has the capability to remove CO2 from a low- pressure source, and subsequently store, compress, and deliver at a higher pressure as required by a processor. The TSAC is an ideal interface device for CO2 removal and reduction units in the air revitalization loop of a spacecraft for oxygen recovery. This paper discusses the design and testing of a TSAC for carbon dioxide that has application in the ISS and future spacecraft for closing the air revitalization loop.

  5. Ames Air Revitalization

    NASA Technical Reports Server (NTRS)

    Huang, Roger Z.

    2015-01-01

    This is an informal presentation presented to the University of Colorado, Boulder Bioastronautics group seminar. It highlights the key focal areas of the Air Revitalization Group research over the past year, including progress on the CO2 Removal and Compression System, testing of CDRA drying bed configurations, and adsorption research.

  6. Long-Duration Testing of a Temperature-Swing Adsorption Compressor for Carbon Dioxide for Closed-Loop Air Revitalization Systems

    NASA Technical Reports Server (NTRS)

    Rosen, Micha; Mulloth, Lila; Varghese, Mini

    2005-01-01

    This paper describes the results of long-duration testing of a temperature-swing adsorption compressor that has application in the International Space Station (ISS) and future spacecraft for closing the air revitalization loop. The air revitalization system of the ISS operates in an open loop mode and relies on the resupply of oxygen and other consumables from Earth for the life support of astronauts. A compressor is required for delivering the carbon dioxide from a removal assembly to a reduction unit to recover oxygen and thereby closing the air-loop. The TSAC is a solid-state compressor that has the capability to remove CO2 from a low-pressure source, and subsequently store, compress, and deliver at a higher pressure as required by a processor. The TSAC is an ideal interface device for CO2 removal and reduction units in the air revitalization loop of a spacecraft for oxygen recovery. The TSAC was developed and its operation was successfully verified in integration tests with the flight-like Carbon Dioxide Removal Assembly (CDRA) at Marshall Space Flight Center prior to the long-duration tests. Long-duration tests reveal the impacts of repeated thermal cycling on the compressor components and the adsorbent material.

  7. Integrated Testing of a Carbon Dioxide Removal Assembly and a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization

    NASA Technical Reports Server (NTRS)

    Knox, J. C.; Mulloth, Lila; Frederick, Kenneth; Affleck, Dave

    2003-01-01

    Accumulation and subsequent compression of carbon dioxide that is removed from space cabin are two important processes involved in a closed-loop air revitalization scheme of the International Space Station (ISS). The carbon dioxide removal assembly (CDRA) of ISS currently operates in an open loop mode without a compressor. This paper describes the integrated test results of a flight-like CDRA and a temperature-swing adsorption compressor (TSAC) for carbon dioxide removal and compression. The paper provides details of the TSAC operation at various CO2 loadings and corresponding performance of CDRA.

  8. Advanced air revitalization system testing

    NASA Technical Reports Server (NTRS)

    Heppner, D. B.; Hallick, T. M.; Schubert, F. H.

    1983-01-01

    A previously developed experimental air revitalization system was tested cyclically and parametrically. One-button startup without manual interventions; extension by 1350 hours of tests with the system; capability for varying process air carbon dioxide partial pressure and humidity and coolant source for simulation of realistic space vehicle interfaces; dynamic system performance response on the interaction of the electrochemical depolarized carbon dioxide concentrator, the Sabatier carbon dioxide reduction subsystem, and the static feed water electrolysis oxygen generation subsystem, the carbon dioxide concentrator module with unitized core technology for the liquid cooled cell; and a preliminary design for a regenerative air revitalization system for the space station are discussed.

  9. Integrated Testing of a 4-Bed Molecular Sieve and a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Mulloth, Lila M.; Affleck, David L.

    2004-01-01

    Accumulation and subsequent compression of carbon dioxide that is removed from space cabin are two important processes involved in a closed-loop air revitalization scheme of the International Space Station (ISS). The 4-Bed Molecular Sieve (4BMS) of ISS currently operates in an open loop mode without a compressor. This paper reports the integrated 4BMS and liquid-cooled TSAC testing conducted during the period of March 3 to April 18, 2003. The TSAC prototype was developed at NASA Ames Research Center (ARC). The 4BMS was modified to a functionally flight-like condition at NASA Marshall Space Flight Center (MSFC). Testing was conducted at MSFC. The paper provides details of the TSAC operation at various CO2 loadings and corresponding performance of CDRA.

  10. Development of a Next-Generation Membrane-Integrated Adsorption Processor for CO2 Removal and Compression for Closed-Loop Air Revitalization Systems

    NASA Technical Reports Server (NTRS)

    Mulloth, Lila; LeVan, Douglas

    2002-01-01

    The current CO2 removal technology of NASA is very energy intensive and contains many non-optimized subsystems. This paper discusses the concept of a next-generation, membrane integrated, adsorption processor for CO2 removal nd compression in closed-loop air revitalization systems. This processor will use many times less power than NASA's current CO2 removal technology and will be capable of maintaining a lower CO2 concentration in the cabin than that can be achieved by the existing CO2 removal systems. The compact, consolidated, configuration of gas dryer, CO2 separator, and CO2 compressor will allow continuous recycling of humid air in the cabin and supply of compressed CO2 to the reduction unit for oxygen recovery. The device has potential application to the International Space Station and future, long duration, transit, and planetary missions.

  11. Preprototype independent air revitalization subsystem

    NASA Technical Reports Server (NTRS)

    Schubert, F. H.; Hallick, T. M.; Woods, R. R.

    1982-01-01

    The performance and maturity of a preprototype, three-person capacity, automatically controlled and monitored, self-contained independent air revitalization subsystem were evaluated. The subsystem maintains the cabin partial pressure of oxygen at 22 kPa (3.2 psia) and that of carbon dioxide at 400 Pa (3 mm Hg) over a wide range of cabin air relative humidity conditions. Consumption of water vapor by the water vapor electrolysis module also provides partial humidity control of the cabin environment. During operation, the average carbon dioxide removal efficiency at baseline conditions remained constant throughout the test at 84%. The average electrochemical depolarized concentrator cell voltage at the end of the parametric/endurance test was 0.41 V, representing a very slowly decreasing average cell voltage. The average water vapor electrolysis cell voltage increased only at a rate of 20 mu/h from the initial level of 1.67 V to the final level of 1.69 V at conclusion of the testing.

  12. Electrochemical air revitalization system optimization investigation

    NASA Technical Reports Server (NTRS)

    Woods, R. R.; Schubert, F. H.; Hallick, T. M.

    1975-01-01

    A program to characterize a Breadboard of an Electrochemical Air Revitalization System (BEARS) was successfully completed. The BEARS is composed of three components: (1) a water vapor electrolysis module (WVEM) for O2 production and partial humidity control, (2) an electrochemical depolarized carbon dioxide concentrator module (EDCM) for CO2 control, and (3) a power-sharing controller, designed to utilize the power produced by the EDCM to partially offset the WVEM power requirements. It is concluded from the results of this work that the concept of electrochemical air revitalization with power-sharing is a viable solution to the problem of providing a localized topping force for O2 generation, CO2 removal and partial humidity control aboard manned spacecraft. Continued development of the EARS concept is recommended, applying the operational experience and limits identified during the BEARS program to testing of a one-man capacity system and toward the development of advanced system controls to optimize EARS operation for given interfaces and requirements. Successful completion of this development will produce timely technology necessary to plan future advanced environmental control and life support system programs and experiments.

  13. Development of a Test Facility for Air Revitalization Technology Evaluation

    NASA Technical Reports Server (NTRS)

    Lu, Sao-Dung; Lin, Amy; Campbell, Melissa; Smith, Frederick; Curley, Su

    2007-01-01

    Development of new air revitalization system (ARS) technology can initially be performed in a subscale laboratory environment, but in order to advance the maturity level, the technology must be tested in an end-to-end integrated environment. The Air Revitalization Technology Evaluation Facility (ARTEF) at the NASA Johnson Space Center serves as a ground test bed for evaluating emerging ARS technologies in an environment representative of spacecraft atmospheres. At the center of the ARTEF is a hypobaric chamber which serves as a sealed atmospheric chamber for closed loop testing. A Human Metabolic Simulator (HMS) was custom-built to simulate the consumption of oxygen, and production of carbon dioxide, moisture and heat of up to eight persons. A multitude of gas analyzers and dew point sensors are used to monitor the chamber atmosphere upstream and downstream of a test article. A robust vacuum system is needed to simulate the vacuum of space. A reliable data acquisition and control system is required to connect all the subsystems together. This paper presents the capabilities of the integrated test facility and some of the issues encountered during the integration.

  14. HESTIA Phase I Test Results: The Air Revitalization System

    NASA Technical Reports Server (NTRS)

    Wright, Sarah E.; Hansen, Scott W.

    2016-01-01

    In any human spaceflight mission, a number of Environmental Control & Life Support System (ECLSS) technologies work together to provide the conditions astronauts need to live healthily, productively, and comfortably in space. In a long-duration mission, many of these ECLSS technologies may use materials supplied by In-Situ Resource Utilization (ISRU), introducing more interactions between systems. The Human Exploration Spacecraft Test-bed for Integration & Advancement (HESTIA) Project aims to create a test-bed to evaluate ECLSS and ISRU technologies and how they interact in a high-fidelity, closed-loop, human-rated analog habitat. Air purity and conditioning are essential components within any ECLSS and for HESTIA's first test they were achieved with the Air Revitalization System (ARS) described below. The ARS provided four essential functions to the test-bed chamber: cooling the air, removing humidity from the air, removing trace contaminants, and scrubbing carbon dioxide (CO2) from the air. In this case, the oxygen supply function was provided by ISRU. In the current configuration, the ARS is a collection of different subsystems. A fan circulates the air, while a condensing heat exchanger (CHX) pulls humidity out of the air. A Trace Contaminant Removal System (TCRS) filters the air of potentially harmful contaminants. Lastly, a Reactive Plastic Lithium Hydroxide (RP-LiOH) unit removes CO2 from the breathing air. During the HESTIA Phase I test in September 2015, the ARS and its individual components each functioned as expected, although further analysis is underway. During the Phase I testing and in prior bench-top tests, the energy balance of heat removed by the CHX was not equal to the cooling it received. This indicated possible instrument error and therefore recalibration of the instruments and follow-up testing is planned in 2016 to address the issue. The ARS was tested in conjunction with two other systems: the Human Metabolic Simulator (HMS) and the

  15. Development of a Low-Power CO2 Removal and Compression System for Closed-Loop Air Revitalization in Future Spacecraft

    NASA Technical Reports Server (NTRS)

    Mulloth, Lila M.; Rosen, Micha; Affleck, David; LeVan, M. Douglas; Moate, Joe R.

    2005-01-01

    The current CO2 removal technology of NASA is very energy intensive and contains many non-optimized subsystems. This paper discusses the design and prototype development of a two-stage CO2 removal and compression system that will utilize much less power than NASA s current CO2 removal technology. This integrated system contains a Nafion membrane followed by a residual water adsorber that performs the function of the desiccant beds in the four-bed molecular sieve (4BMS) system of the International Space Station (ISS). The membrane and the water adsorber are followed by a two-stage CO2 removal and compression subsystem that satisfies the operations of the CO2 adsorbent beds of the 4BMS aid the interface compressor for the Sabatier reactor connection. The two-stage compressor will utilize the principles of temperature-swing adsorption (TSA) compression technology for CO2 removal and compression. The similarities in operation and cycle times of the CO2 removal (first stage) and compression (second stage) operations will allow thermal coupling of the processes to maximize the efficiency of the system. In addition to the low-power advantage, this processor will maintain a lower CO2 concentration in the cabin than that can be achieved by the existing CO2 removal systems. The compact, consolidated, configuration of membrane gas dryer and CO2 separator and compressor will allow continuous recycling of humid air in the cabin and supply of compressed CO2 to the reduction unit for oxygen recovery. The device has potential application to the International Space Station and future, long duration, transit, and planetary missions.

  16. Mathematical model of one-man air revitalization system

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A mathematical model was developed for simulating the steady state performance in electrochemical CO2 concentrators which utilize (NMe4)2 CO3 (aq.) electrolyte. This electrolyte, which accommodates a wide range of air relative humidity, is most suitable for one-man air revitalization systems. The model is based on the solution of coupled nonlinear ordinary differential equations derived from mass transport and rate equations for the processes which take place in the cell. The boundary conditions are obtained by solving the mass and energy transport equations. A shooting method is used to solve the differential equations.

  17. Design and Sizing of the Air Revitalization System for Altair Lunar Lander

    NASA Technical Reports Server (NTRS)

    Allada, Rama Kumar

    2009-01-01

    Designing closed-loop Air Revitalization Systems (ARS) for human spaceflight applications requires a delicate balance between designing for system robustness while minimizing system power and mass requirements. This presentation will discuss the design of the ARS for the Altair Lunar Lander. The presentation will illustrate how dynamic simulations, using Aspen Custom Modeler, were used to develop a system configuration with the ability to control atmospheric conditions under a wide variety of circumstances while minimizing system mass/volume and the impact on overall power requirements for the Lander architecture.

  18. One-man electrochemical air revitalization system evaluation

    NASA Technical Reports Server (NTRS)

    Schbert, F. H.; Marshall, R. D.; Hallick, T. M.; Woods, R. R.

    1976-01-01

    A program to evaluate the performance of a one man capacity, self contained electrochemical air revitalization system was successfully completed. The technology readiness of this concept was demonstrated by characterizing the performance of this one man system over wide ranges in cabin atmospheric conditions. The electrochemical air revitalization system consists of a water vapor electrolysis module to generate oxygen from water vapor in the cabin air, and an electrochemical depolarized carbon dioxide concentrator module to remove carbon dioxide from the cabin air. A control/monitor instrumentation package that uses the electrochemical depolarized concentrator module power generated to partially offset the water vapor electrolysis module power requirements and various structural fluid routing components are also part of the system. The system was designed to meet the one man metabolic oxygen generation and carbon dioxide removal requirements, thereby controlling cabin partial pressure of oxygen at 22 kN/sq m and cabin pressure of carbon dioxide at 400 N/sq m over a wide range in cabin air relative humidity conditions.

  19. One man electrochemical air revitalization system

    NASA Technical Reports Server (NTRS)

    Huddleston, J. C.; Aylward, J. R.

    1975-01-01

    An integrated water vapor electrolysis (WVE) hydrogen depolarized CO2 concentrator (HDC) system sized for one man support over a wide range of inlet air conditions was designed, fabricated, and tested. Data obtained during 110 days of testing verified that this system can provide the necessary oxygen, CO2 removal, and partial humidity control to support one man (without exceeding a cabin partial pressure of 3.0 mmHg for CO2 and while maintaining a 20% oxygen level), when operated at a WVE current of 50 amperes and an HDC current of 18 amperes. An evaluation to determine the physical properties of tetramethylammonium bicarbonate (TMAC) and hydroxide was made. This provides the necessary electrolyte information for designing an HDC cell using TMAC.

  20. An integrated regenerative air revitalization system for spacecraft

    NASA Technical Reports Server (NTRS)

    Noyes, G. P.; Heppner, D. B.; Schubert, F. H.; Quattrone, P. D.

    1982-01-01

    Progress towards development of an air revitalization system (ARS) for spacecraft breathable atmosphere regeneration is assessed, and a preliminary design for a one-person ARS is described. The ARS is considered a necessary component of any permanently manned orbital station, and studies have demonstrated that penalties for expendable air supplies justify an ARS for missions longer than 40 days. CO2 must be removed and O2 returned along with N2, which can be extracted from hydrazine, with the H2 component returning to the operation of the CO2 reduction subsystem. An experimental ARS (ARX-1) features a cabin humidity control unit, a CO2 concentrator, an air-cooled CO2 reduction reactor, an oxygen generator (electrolysis), the hydrazine N2 generator, and a water handling unit. A 120-day test demonstrated one-button startup and 480 hr operation in a normal mode.

  1. Environmental Assessment: Eagle Heights Housing Area Revitalization Dover Air Force Base, Delaware

    DTIC Science & Technology

    2004-07-01

    anticipated Biological Resources • Demolition and construction activities would create a short-term impact to wildlife • Most species within the Eagle ... biological resources comprises the Environmental Assessment for Eagle Heights Housing Revitalization 711510412:27 PMI039-o4 Dover Air Force Base...COVERED 00-00-2004 to 00-00-2004 4. TITLE AND SUBTITLE Environmental Assessment Eagle Heights Housing Area Revitalization Dover Air Force Base

  2. Dynamic Model of the BIO-Plex Air Revitalization System

    NASA Technical Reports Server (NTRS)

    Finn, Cory; Meyers, Karen; Duffield, Bruce; Luna, Bernadette (Technical Monitor)

    2000-01-01

    The BIO-Plex facility will need to support a variety of life support system designs and operation strategies. These systems will be tested and evaluated in the BIO-Plex facility. An important goal of the life support program is to identify designs that best meet all size and performance constraints for a variety of possible future missions. Integrated human testing is a necessary step in reaching this goal. System modeling and analysis will also play an important role in this endeavor. Currently, simulation studies are being used to estimate air revitalization buffer and storage requirements in order to develop the infrastructure requirements of the BIO-Plex facility. Simulation studies are also being used to verify that the envisioned operation strategy will be able to meet all performance criteria. In this paper, a simulation study is presented for a nominal BIO-Plex scenario with a high-level of crop growth. A general description of the dynamic mass flow model is provided, along with some simulation results. The paper also discusses sizing and operations issues and describes plans for future simulation studies.

  3. STS-32 OV-102 air revitalization system (ARS) humidity separator problem

    NASA Technical Reports Server (NTRS)

    1990-01-01

    During STS-32, onboard Columbia, Orbiter Vehicle (OV) 102, a leakage problem at environmental control and life support system (ECLSS) air revitalization system (ARS) humidity separator A below the middeck is solved with a plastic bag and a towel. The towel inserted inside a plastic bag absorbed the water that had collected at the separator inlet.

  4. Thirsty Walls: A New Paradigm for Air Revitalization in Life Support

    NASA Technical Reports Server (NTRS)

    Graf, John; Brennecke, Joan; Weislogel, Mark

    2015-01-01

    Carbon Dioxide removal systems on submarines are compact and reliable. They use solubility chemistry. They spray a Carbon Dioxide adsorbing chemical directly into the air stream, and allow the liquid to settle. Carbon Dioxide removal systems on ISS are large and need repair. They use adsorption chemistry. They force air through a bed packed with granular zeolite, and heat the bed to desorb the Carbon Dioxide. The thermal cycles cause the zeolite to dust. New advances in additive manufacturing, and a better understanding of uid behavior in microgravity make it possible to expose a liquid directly to air in a microgravity environment. It is now practical to use submarine style solubility chemistry for atmosphere revitalization in space. It is now possible to develop space systems that achieve submarine levels of reliability. New developments in Ionic Liquid research make it possible to match the solubility performance characteristics of MEA used on submarines - with Ionic Liquids that do not release chemical vapors into the air. "Thirsty Walls" provide gentle, passive contact between ventilation air and Air Revitalization functions of temperature control, relative humidity control, and Carbon Dioxide removal. "Thirsty Walls" eliminates the need of large blowers and compressors that need to force air at high velocities through restrictive Air Revitalization hardware.

  5. Carbon dioxide removal system for closed loop atmosphere revitalization, candidate sorbents screening and test results

    NASA Astrophysics Data System (ADS)

    Mattox, E. M.; Knox, J. C.; Bardot, D. M.

    2013-05-01

    Due to the difficulty and expense it costs to resupply manned-spacecraft habitats, a goal is to create a closed loop atmosphere revitalization system, in which precious commodities such as oxygen, carbon dioxide, and water are continuously recycled. Our aim is to test other sorbents for their capacity for future spacecraft missions, such as on the Orion spacecraft, or possibly lunar or Mars mission habitats to see if they would be better than the zeolite sorbents on the 4-bed molecular sieve. Some of the materials being tested are currently used for other industry applications. Studying these sorbents for their specific spacecraft application is different from that for applications on earth because in space, there are certain power, mass, and volume limitations that are not as critical on Earth. In manned-spaceflight missions, the sorbents are exposed to a much lower volume fraction of CO2 (0.6% volume CO2) than on Earth. LiLSX was tested for its CO2 capacity in an atmosphere like that of the ISS. Breakthrough tests were run to establish the capacities of these materials at a partial pressure of CO2 that is seen on the ISS. This paper discusses experimental results from benchmark materials, such as results previously obtained from tests on Grade 522, and the forementioned candidate materials for the Carbon Dioxide Removal Assembly (CDRA) system.

  6. Effects of Humidity Swings on Adsorption Columns for Air Revitalization: Modeling and Experiments

    NASA Technical Reports Server (NTRS)

    LeVan, M. Douglas; Finn, John E.

    1997-01-01

    Air purification systems are necessary to provide clean air in the closed environments aboard spacecraft. Trace contaminants are removed using adsorption. One major factor concerning the removal of trace contaminants is relative humidity. Water can reduce adsorption capacity and, due to constant fluctuations, its presence is difficult to incorporate into adsorption column designs. The purpose of the research was to allow for better design techniques in trace contaminant adsorption systems, especially for feeds with water present. Experiments and mathematical modeling research on effects of humidity swings on adsorption columns for air revitalization were carried out.

  7. Air Revitalization System Enables Excursions to the Stratosphere

    NASA Technical Reports Server (NTRS)

    2015-01-01

    Paragon Space Development Corporation, based in Tucson, Arizona has had a long history of collaboration with NASA, including developing a modular air purification system under the Commercial Crew Development Program, designed to support the commercial space sector. Using that device and other NASA technology, startup company World View is now gearing up to take customers on helium balloon rides to the stratosphere.

  8. Modeling of membrane processes for air revitalization and water recovery

    NASA Technical Reports Server (NTRS)

    Lange, Kevin E.; Foerg, Sandra L.; Dall-Bauman, Liese A.

    1992-01-01

    Gas-separation and reverse-osmosis membrane models are being developed in conjunction with membrane testing at NASA JSC. The completed gas-separation membrane model extracts effective component permeabilities from multicomponent test data, and predicts the effects of flow configuration, operating conditions, and membrane dimensions on module performance. Variable feed- and permeate-side pressures are considered. The model has been applied to test data for hollow-fiber membrane modules with simulated cabin-air feeds. Results are presented for a membrane designed for air drying applications. Extracted permeabilities are used to predict the effect of operating conditions on water enrichment in the permeate. A first-order reverse-osmosis model has been applied to test data for spiral wound membrane modules with a simulated hygiene water feed. The model estimates an effective local component rejection coefficient under pseudosteady-state conditions. Results are used to define requirements for a detailed reverse-osmosis model.

  9. Multi-Agent Diagnosis and Control of an Air Revitalization System for Life Support in Space

    NASA Technical Reports Server (NTRS)

    Malin, Jane T.; Kowing, Jeffrey; Nieten, Joseph; Graham, Jeffrey s.; Schreckenghost, Debra; Bonasso, Pete; Fleming, Land D.; MacMahon, Matt; Thronesbery, Carroll

    2000-01-01

    An architecture of interoperating agents has been developed to provide control and fault management for advanced life support systems in space. In this adjustable autonomy architecture, software agents coordinate with human agents and provide support in novel fault management situations. This architecture combines the Livingstone model-based mode identification and reconfiguration (MIR) system with the 3T architecture for autonomous flexible command and control. The MIR software agent performs model-based state identification and diagnosis. MIR identifies novel recovery configurations and the set of commands required for the recovery. The AZT procedural executive and the human operator use the diagnoses and recovery recommendations, and provide command sequencing. User interface extensions have been developed to support human monitoring of both AZT and MIR data and activities. This architecture has been demonstrated performing control and fault management for an oxygen production system for air revitalization in space. The software operates in a dynamic simulation testbed.

  10. Evaluation of Sorbents for Acetylene Separation in Atmosphere Revitalization Loop Closure

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Miller, Lee A.; Barton, Katherine

    2011-01-01

    State-of-the-art carbon dioxide reduction technology uses a Sabatier reactor to recover water from metabolic carbon dioxide. In order to maximize oxygen loop closure, a byproduct of the system, methane, must be reduced to recover hydrogen. NASA is currently exploring a microwave plasma methane pyrolysis system for this purpose. The resulting product stream of this technology includes unreacted methane, product hydrogen, and acetylene. The hydrogen and the small amount of unreacted methane resulting from the pyrolysis process can be returned to the Sabatier reactor thereby substantially improving the overall efficiency of the system. However, the acetylene is a waste product that must be removed from the pyrolysis product. Two materials have been identified as potential sorbents for acetylene removal: zeolite 4A, a commonly available commercial sorbent, and HKUST-1, a newly developed microporous metal. This paper provides an explanation of the rationale behind acetylene removal and the results of separation testing with both materials.

  11. Evaluation of Sorbents for Acetylene Separation in Atmosphere Revitalization Loop Closure

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Miller, Lee A.; Barton, Katherine

    2012-01-01

    State-of-the-art carbon dioxide reduction technology uses a Sabatier reactor to recover water from metabolic carbon dioxide. In order to maximize oxygen loop closure, a byproduct of the system, methane, must be reduced to recover hydrogen. NASA is currently exploring a microwave plasma methane pyrolysis system for this purpose. The resulting product stream of this technology includes unreacted methane, product hydrogen, and acetylene. The hydrogen and the small amount of unreacted methane resulting from the pyrolysis process can be returned to the Sabatier reactor thereby substantially improving the overall efficiency of the system. However, the acetylene is a waste product that must be removed from the pyrolysis product. Two materials have been identified as potential sorbents for acetylene removal: zeolite 4A, a commonly available commercial sorbent, and HKUST-1, a newly developed microporous metal. This paper provides an explanation of the rationale behind acetylene removal and the results of separation testing with both materials

  12. A Discussion of Oxygen Recovery Definitions and Key Performance Parameters for Closed-Loop Atmosphere Revitalization Life Support Technology Development

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Perry, Jay L.

    2016-01-01

    Over the last 55 years, NASA has evolved life support for crewed space exploration vehicles from simple resupply during Project Mercury to the complex and highly integrated system of systems aboard the International Space Station. As NASA targets exploration destinations farther from low Earth orbit and mission durations of 500 to 1000 days, life support systems must evolve to meet new requirements. In addition to having more robust, reliable, and maintainable hardware, limiting resupply becomes critical for managing mission logistics and cost. Supplying a crew with the basics of food, water, and oxygen become more challenging as the destination ventures further from Earth. Aboard ISS the Atmosphere Revitalization Subsystem (ARS) supplies the crew's oxygen demand by electrolyzing water. This approach makes water a primary logistics commodity that must be managed carefully. Chemical reduction of metabolic carbon dioxide (CO2) provides a method of recycling oxygen thereby reducing the net ARS water demand and therefore minimizing logistics needs. Multiple methods have been proposed to achieve this recovery and have been reported in the literature. However, depending on the architecture and the technology approach, "oxygen recovery" can be defined in various ways. This discontinuity makes it difficult to compare technologies directly. In an effort to clarify community discussions of Oxygen Recovery, we propose specific definitions and describe the methodology used to arrive at those definitions. Additionally, we discuss key performance parameters for Oxygen Recovery technology development including challenges with comparisons to state-of-the-art.

  13. Closed-loop air cooling system for a turbine engine

    DOEpatents

    North, William Edward

    2000-01-01

    Method and apparatus are disclosed for providing a closed-loop air cooling system for a turbine engine. The method and apparatus provide for bleeding pressurized air from a gas turbine engine compressor for use in cooling the turbine components. The compressed air is cascaded through the various stages of the turbine. At each stage a portion of the compressed air is returned to the compressor where useful work is recovered.

  14. Seeing It Coming: Revitalizing Future Studies in the US Air Force

    DTIC Science & Technology

    2012-10-01

    Gulliver’s Travails ,” “Zaibatsu,” “Digital Cacophony,” and “King Khan” scenarios developed in the Air Force’s Alternate Futures for 2025 study of... motivate the Air Force to turn away from the myopic tendencies that have become so prevalent and renew its focus on future studies. Anticipation of the

  15. Revitalization of School Facilities.

    ERIC Educational Resources Information Center

    Coffey, Andrea Barlow

    This study analyzed current practices in the revitalization of school buildings and assimilates data that can be used by school administrators when deciding on revitalization issues. Data from nine revitalized schools since 1985 and a literature review of the elements for planning the revitalization of school facilities indicate that structural…

  16. Mathematical Analysis of High-Temperature Co-electrolysis of CO2 and O2 Production in a Closed-Loop Atmosphere Revitalization System

    SciTech Connect

    Michael G. McKellar; Manohar S. Sohal; Lila Mulloth; Bernadette Luna; Morgan B. Abney

    2010-03-01

    NASA has been evaluating two closed-loop atmosphere revitalization architectures based on Sabatier and Bosch carbon dioxide, CO2, reduction technologies. The CO2 and steam, H2O, co-electrolysis process is another option that NASA has investigated. Utilizing recent advances in the fuel cell technology sector, the Idaho National Laboratory, INL, has developed a CO2 and H2O co-electrolysis process to produce oxygen and syngas (carbon monoxide, CO and hydrogen, H2 mixture) for terrestrial (energy production) application. The technology is a combined process that involves steam electrolysis, CO2 electrolysis, and the reverse water gas shift (RWGS) reaction. A number of process models have been developed and analyzed to determine the theoretical power required to recover oxygen, O2, in each case. These models include the current Sabatier and Bosch technologies and combinations of those processes with high-temperature co-electrolysis. The cases of constant CO2 supply and constant O2 production were evaluated. In addition, a process model of the hydrogenation process with co-electrolysis was developed and compared. Sabatier processes require the least amount of energy input per kg of oxygen produced. If co-electrolysis replaces solid polymer electrolyte (SPE) electrolysis within the Sabatier architecture, the power requirement is reduced by over 10%, but only if heat recuperation is used. Sabatier processes, however, require external water to achieve the lower power results. Under conditions of constant incoming carbon dioxide flow, the Sabatier architectures require more power than the other architectures. The Bosch, Boudouard with co-electrolysis, and the hydrogenation with co-electrolysis processes require little or no external water. The Bosch and hydrogenation processes produce water within their reactors, which aids in reducing the power requirement for electrolysis. The Boudouard with co-electrolysis process has a higher electrolysis power requirement because carbon

  17. Air Revitalization Using Superoxides

    NASA Technical Reports Server (NTRS)

    Wydeven, Theodore; Wood, Peter C.; Spitze, L. A.

    1988-01-01

    Pellets made from powder mixtures of potassium superoxide, KO2, and calcium superoxide, Ca(O2)2, proven markedly superior to pellets of pure KO2 for adding O2 to and removing CO2 from atmospheric-pressure flow of humidified CO2 in He. Superoxides used extensively to supply O2 and scrub CO2 in variety of ambient-pressure life-support applications, including portable self-contained breathing apparatuses, spacecraft, and undersea submersible craft.

  18. Land Revitalization Basics

    EPA Pesticide Factsheets

    EPA created the Land Revitalization Initiative to promote cross-program coordination on land reuse and revitalization projects to ensure that contaminated property is appropriately put back into productive use.

  19. Closed loop air cooling system for combustion turbines

    DOEpatents

    Huber, David John; Briesch, Michael Scot

    1998-01-01

    Convective cooling of turbine hot parts using a closed loop system is disclosed. Preferably, the present invention is applied to cooling the hot parts of combustion turbine power plants, and the cooling provided permits an increase in the inlet temperature and the concomitant benefits of increased efficiency and output. In preferred embodiments, methods and apparatus are disclosed wherein air is removed from the combustion turbine compressor and delivered to passages internal to one or more of a combustor and turbine hot parts. The air cools the combustor and turbine hot parts via convection and heat is transferred through the surfaces of the combustor and turbine hot parts.

  20. Closed loop air cooling system for combustion turbines

    DOEpatents

    Huber, D.J.; Briesch, M.S.

    1998-07-21

    Convective cooling of turbine hot parts using a closed loop system is disclosed. Preferably, the present invention is applied to cooling the hot parts of combustion turbine power plants, and the cooling provided permits an increase in the inlet temperature and the concomitant benefits of increased efficiency and output. In preferred embodiments, methods and apparatus are disclosed wherein air is removed from the combustion turbine compressor and delivered to passages internal to one or more of a combustor and turbine hot parts. The air cools the combustor and turbine hot parts via convection and heat is transferred through the surfaces of the combustor and turbine hot parts. 1 fig.

  1. Gateways Revitalization Strategy

    EPA Pesticide Factsheets

    Lancaster County, PA, created the Gateway plan to reconnect various areas of the community, revitalize the economic base, improve and build on infrastructure and public/private partnerships, and retain current residents.

  2. A Revitalized USAF Culture of Innovation

    DTIC Science & Technology

    2013-11-01

    i   SQUADRON OFFICER COLLEGE AIR UNIVERSITY A REVITALIZED USAF CULTURE OF INNOVATION By Capt Vito Bussmann, Capt Gabriel Gassie, Capt...NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Air University,Squadron Officer College ,Maxwell AFB,AL...inputs from senior leadership on-site at Air University and Squadron Officer College to guide the direction of our research. Our research placed an

  3. Ontology for Life-Cycle Modeling of Heating, Ventilating, and Air Conditioning (HVAC) Systems: Experimental Applications Using Revit

    DTIC Science & Technology

    2012-03-01

    Center, Construction Engineering Research Laboratory (ERDC-CERL) has developed a core life- cycle building information model ( BIM ) based on three...was to promote consistency and quality of content created for Building Information Models ( BIMs ) across various disciplines. The HVAC MVD was...MVD. 15. SUBJECT TERMS building information modeling ( BIM ), ontology, Army facilities, heating, ventilating, and air-conditioning (HVAC) systems

  4. Designing Indigenous Language Revitalization

    ERIC Educational Resources Information Center

    Hermes, Mary; Bang, Megan; Marin, Ananda

    2012-01-01

    Endangered Indigenous languages have received little attention within the American educational research community. However, within Native American communities, language revitalization is pushing education beyond former iterations of culturally relevant curriculum and has the potential to radically alter how we understand culture and language in…

  5. The Revitalized Tutoring Center

    ERIC Educational Resources Information Center

    Koselak, Jeremy

    2017-01-01

    One high-leverage strategy rooted in a strong research base--the revitalized tutoring center--provides a wealth of opportunity to students who may be otherwise underserved. This embedded, open-all-day tutoring center supports collaborative teacher teams by using peer tutors and community volunteers. By centralizing resources and providing supports…

  6. Programming of Urban Revitalization

    NASA Astrophysics Data System (ADS)

    Biliński, Tadeusz

    2016-12-01

    The planning stage of the investment-construction process is of a crucial importance. Its overall impact on the costs, construction time and the quality of design solutions is huge. However, in practice, little attention is given to this pre-design stage, except for public buildings or other buildings of particular importance. In consequence, the results of investment and construction activities are unsatisfactory. Therefore, the issue has been given careful consideration in this paper. The paper discusses the issue of programming urban revitalization, emphasizing its socio-economic importance. To illustrate the complexity of revitalization projects planning, the author draws attention to social, economic, technical and organisational factors, such as public participation, reorganization and revaluation of land use planning, rationalization of energy use, organization and management of revitalization processes, as well as technical progress. Summarising the paper, the author concludes that in order to improve the quality of life of town residents and to protect material national heritage, it is indispensable to continuously revitalize subsequent town areas.

  7. Modeling of Atmosphere Revitalization

    NASA Technical Reports Server (NTRS)

    Coker, Robert; Knox, James; Kittredge, Kenneth

    2012-01-01

    NASA's AES is pioneering new approaches for future human missions beyond Earth orbit. All spacecraft systems must be minimized with respect to mass, power, and volume. Here, we show work related to improving system efficiency and reliability for water separation systems on crewed vehicles and the initial development of COMSOL simulations in support of the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project

  8. Transient performance and temperature field of a natural convection air dehumidifier loop

    NASA Astrophysics Data System (ADS)

    Fazilati, Mohammad Ali; Sedaghat, Ahmad; Alemrajabi, Ali-Akbar

    2017-02-01

    In this paper, transient performance of the previously introduced natural convection heat and mass transfer loop is investigated for an air dehumidifier system. The performance of the loop is studied in different conditions of heat source/heat sink temperature and different startup desiccant concentrations. Unlike conventional loops, it is observed that natural convection of the fluid originates from the heat sink towards the heat source. The proper operation of the cycle is highly dependent on the heat sink/heat source temperatures. To reduce the time constant of the system, a proper desiccant concentration should be adopted for charge of the loop.

  9. CO2 Removal and Atmosphere Revitalization Systems for Next Generation Space Flight

    NASA Technical Reports Server (NTRS)

    Luna, Bernadette; Mulloth, Lila M.; Varghese, Mini M.; Hogan, John Andrew

    2010-01-01

    Removal of metabolic CO2 from breathing air is a vital process for life support in all crewed space missions. A CO2 removal processor called the Low Power CO2 Removal (LPCOR) system is being developed in the Bioengineering Branch at NASA Ames Research Center. LPCOR utilizes advanced adsorption and membrane gas separation processes to achieve substantial power and mass reduction when compared to the state-of-the-art carbon dioxide removal assembly (CORA) of the US segment of the International Space Station (ISS). LPCOR is an attractive alternative for use in commercial spacecraft for short-duration missions and can easily be adapted for closed-loop life support applications. NASA envisions a next-generation closed-loop atmosphere revitalization system that integrates advanced CO2 removal, O2 recovery, and trace contaminant control processes to improve overall system efficiency. LPCOR will serve as the front end to such a system. LPCOR is a reliable air revitalization technology that can serve both the near-term and long-term human space flight needs of NASA and its commercial partners.

  10. Energy efficiency in military housing: Monitoring to support revitalization guidebook

    SciTech Connect

    Levins, W.P.; Ternes, M.P.

    1994-11-01

    Oak Ridge National Laboratory is working with the US Army, the US Air Force, and the US Department of Energy to develop a guidebook to be used by architectural and engineering firms in the design phases of military family housing revitalization projects. The purpose of the guidebook is to ensure that energy efficiency is properly addressed in revitalization projects. Monitoring space-heating and cooling energy used in houses both before and after they are revitalized is necessary in order to assess the amount of energy saved by the revitalization process. Three different methods of conducting monitoring experiments are discussed, as well as the methods of data analysis to be used. Houses will be monitored individually using standard gas and electric meters to obtain heating and cooling data for the houses. The authors recommend conducting monitoring programs at Altus Air Force Base, Oklahoma, and Fort Monmouth, New Jersey, because of their project schedules and potential for savings. They do not recommend doing any monitoring at Malmstrom Air Force Base, Montana, because of the relatively small savings that they expect revitalization to accomplish there. They do not recommend seeking out alternative sites for monitoring because of the time required to become familiar with the installation and also because revitalization schedules at alternative sites may be no better than those at the sites they inspected.

  11. Revitalizing urban waterways

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-07-01

    Eleven U.S. federal agencies have joined together in a new initiative to protect and revitalize urban waterways and communities. The Urban Waters Federal Partnership, announced on 24 June, is focusing on seven pilot locations to help urban communities reconnect with and revitalize their waterways, according to Lisa Jackson, administrator of the U.S. Environmental Protection Agency (EPA), which launched the initiative. “Urban waters have the potential to support healthy environments, growing businesses, and educational and recreational activities. By bringing together the experience and expertise of multiple federal partners, we have a chance to reconnect local residents, young people, and community groups with the environmental resources all around them,” she said.

  12. Film cooling air pocket in a closed loop cooled airfoil

    DOEpatents

    Yu, Yufeng Phillip; Itzel, Gary Michael; Osgood, Sarah Jane; Bagepalli, Radhakrishna; Webbon, Waylon Willard; Burdgick, Steven Sebastian

    2002-01-01

    Turbine stator vane segments have radially inner and outer walls with vanes extending between them. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. To provide for air film cooing of select portions of the airfoil outer surface, at least one air pocket is defined on a wall of at least one of the cavities. Each air pocket is substantially closed with respect to the cooling medium in the cavity and cooling air pumped to the air pocket flows through outlet apertures in the wall of the airfoil to cool the same.

  13. Nanoporous Materials in Atmosphere Revitalization. Chapter 1

    NASA Technical Reports Server (NTRS)

    Hernandez-Maldonado, J.; Ishikawa, Yasuyuki; Luna, Bernadette; Junaedi, Christian; Mulloth, Lila; Perry, Jay L.; Raptis, Raphael G.; Roychoudhury, Subir

    2012-01-01

    Atmospheric Revitalization (AR) is the term the National Aeronautics and Space Administration (NASA) uses to encompass the engineered systems that maintain a safe, breathable gaseous atmosphere inside a habitable space cabin. An AR subsystem is a key part of the Environmental Control and Life Support (ECLS) system for habitable space cabins. The ultimate goal for AR subsystem designers is to 'close the loop', that is, to capture gaseous human metabolic products, specifically water vapor (H2O) and Carbon dioxide (CO2), for maximal Oxygen (o2) recovery and to make other useful resources from these products. The AR subsystem also removes trace chemical contaminants from the cabin atmosphere to preserve cabin atmospheric quality, provides O2 and may include instrumentation to monitor cabin atmospheric quality. Long duration crewed space exploration missions require advancements in AR process technologies in order to reduce power consumption and mass and to increase reliability compared to those used for shorter duration missions that are typically limited to Low Earth Orbit. For example, current AR subsystems include separate processors and process air flow loops for removing metabolic CO2 and volatile organic tract contaminants (TCs). Physical adsorbents contained in fixed, packed beds are employed in these processors. Still, isolated pockets of high carbon dioxide have been suggested as a trigger for crew headaches and concern persists about future cabin ammonia (NH3) levels as compared with historical flights. Developers are already focused on certain potential advancements. ECLS systems engineers envision improving the AR subsystem by combining the functions of TC control and CO2 removal into a single regenerable process and moving toward structured sorbents - monoliths - instead of granular material. Monoliths present a lower pressure drop and eliminate particle attrition problems that result from bed containment. New materials and configurations offer promise for

  14. Revitalizing Communities in New Mexico

    ERIC Educational Resources Information Center

    Pitzl, Jerry

    2011-01-01

    The New Mexico Rural Revitalization Initiative (NMRRI), an innovative program to enhance the growth and development of rural communities, involves schools and students as part of a holistic approach. The program requires community members to take responsibility for revitalizing their economy and fosters an entrepreneurial spirit among students.

  15. Determination of air-loop volume and radon partition coefficient for measuring radon in water sample.

    PubMed

    Lee, Kil Yong; Burnett, William C

    A simple method for the direct determination of the air-loop volume in a RAD7 system as well as the radon partition coefficient was developed allowing for an accurate measurement of the radon activity in any type of water. The air-loop volume may be measured directly using an external radon source and an empty bottle with a precisely measured volume. The partition coefficient and activity of radon in the water sample may then be determined via the RAD7 using the determined air-loop volume. Activity ratios instead of absolute activities were used to measure the air-loop volume and the radon partition coefficient. In order to verify this approach, we measured the radon partition coefficient in deionized water in the temperature range of 10-30 °C and compared the values to those calculated from the well-known Weigel equation. The results were within 5 % variance throughout the temperature range. We also applied the approach for measurement of the radon partition coefficient in synthetic saline water (0-75 ppt salinity) as well as tap water. The radon activity of the tap water sample was determined by this method as well as the standard RAD-H2O and BigBottle RAD-H2O. The results have shown good agreement between this method and the standard methods.

  16. The shuttle orbiter cabin atmospheric revitalization systems

    NASA Technical Reports Server (NTRS)

    Ward, C. F.; Owens, W. L.

    1975-01-01

    The Orbiter Atmospheric Revitalization Subsystem (ARS) and Pressure Control Subsystem (ARPCS) are designed to provide the flight crew and passengers with a pressurized environment that is both life-supporting and within crew comfort limitations. The ARPCS is a two-gas (oxygen-nitrogen) system that obtains oxygen from the Power Reactant Supply and Distribution (PRSD) subsystem and nitrogen from the nitrogen storage tanks. The ARS includes the water coolant loop; cabin CO2, odor, humidity and temperature control; and avionics cooling. Baseline ARPCS and ARS changes since 1973 include removal of the sublimator from the water coolant loop, an increase in flowrates to accommodate increased loads, elimination of the avionics bay isolation from the cabin, a decision to have an inert vehicle during ferry flight, elimination of coldwall tubing around windows and hatches, and deletion of the cabin heater.

  17. Simulation Helps Improve Atmosphere Revitalization Systems for Manned Spacecraft

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Coker, RObert

    2014-01-01

    Life support systems for manned spacecraft must provide breathable air and drinkable water for the astronauts. Through the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project, engineers at NASA are developing atmosphere control devices for the safety of the onboard crew. The atmosphere in a manned spacecraft needs to be regularly revitalized in order to ensure the safety of the astronauts and the success of the space mission. For missions lasting a few months, this means air is continuously dehumidified, water collected for re-use, and carbon dioxide (CO2) ejected. One component of the onboard atmosphere control system is a water-saving device that Jim Knox, aerospace engineer at NASA, is optimizing through the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project. He is leading a team at the Marshall Space Flight Center (Huntsville, Alabama) that is aiming to make the assembly more cost-effective and efficient by reducing its power usage and maximizing the water saved; their goal is to save 80-90% of the water in the air. They hope to offer flight system developers at NASA an integrated approach to atmosphere revitalization and water collection that will ultimately increase the time and distance space missions can travel.

  18. Finding of No Significant Impact for Test Capabilities Revitalization at the Aerial Cable Test Facility Kirtland Air Force Base, New Mexico

    DTIC Science & Technology

    2004-01-15

    AFFECTED ENVIRONMENT 3.1 History The original aerial cable, installed in 1971, was a 1 3/8-inch wire rope spanning a 5,000-ft-wide canyon. A rocket... cableways . 3.2 Air Quality Ambient air quality is regulated by the joint Albuquerque-Bernalillo County-Air Quality Control Board (ABC/AQCB). The ABC

  19. SMARTE: IMPROVING REVITALIZATION DECISIONS - OCTOBER 3, 2006

    EPA Science Inventory

    SMARTe (Sustainable Management Approaches and Revitalization Tools -electronic) is a web-based decision support tool being developed by the Office of Research and Development (ORD) in partnership with the Office of Brownfields Cleanup and Revitalization (OBCR), the Interstate Tec...

  20. Language Acquisition and Language Revitalization

    ERIC Educational Resources Information Center

    O'Grady, William; Hattori, Ryoko

    2016-01-01

    Intergenerational transmission, the ultimate goal of language revitalization efforts, can only be achieved by (re)establishing the conditions under which an imperiled language can be acquired by the community's children. This paper presents a tutorial survey of several key points relating to language acquisition and maintenance in children,…

  1. Revitalizing Communities Through Drug Education

    ERIC Educational Resources Information Center

    Gregory, Robert J.

    1974-01-01

    An educational experience can be designed which, besides giving information, provides experiences and opportunities to share in revitalizing the social patterns of the community. A case study, focusing on drug abuse, serves as a base for the description of the process of community education. (Author)

  2. Closed loop engine control for regulating NOx emissions, using a two-dimensional fuel-air curve

    DOEpatents

    Bourn, Gary D.; Smith, Jack A.; Gingrich, Jess W.

    2007-01-30

    An engine control strategy that ensures that NOx emissions from the engine will be maintained at an acceptable level. The control strategy is based on a two-dimensional fuel-air curve, in which air manifold pressure (AMP) is a function of fuel header pressure and engine speed. The control strategy provides for closed loop NOx adjustment to a base AMP value derived from the fuel-air curve.

  3. An Improved Design for Air Removal from Aerospace Fluid Loop Coolant Systems

    NASA Technical Reports Server (NTRS)

    Ritchie, Stephen M. C.; Holladay, Jon B.; Holt, J. Mike; Clark, Dallas W.

    2003-01-01

    Aerospace applications with requirements for large capacity heat removal (launch vehicles, platforms, payloads, etc.) typically utilize a liquid coolant fluid as a transport media to increase efficiency and flexibility in the vehicle design. An issue with these systems however, is susceptibility to the presence of noncondensable gas (NCG) or air. The presence of air in a coolant loop can have numerous negative consequences, including loss of centrifugal pump prime, interference with sensor readings, inhibition of heat transfer, and coolant blockage to remote systems. Hardware ground processing to remove this air is also cumbersome and time consuming which continuously drives recurring costs. Current systems for maintaining the system free of air are tailored and have demonstrated only moderate success. An obvious solution to these problems is the development and advancement of a passive gas removal device, or gas trap, that would be installed in the flight cooling system simplifying the initial coolant fill procedure and also maintaining the system during operations. The proposed device would utilize commercially available membranes thus increasing reliability and reducing cost while also addressing both current and anticipated applications. In addition, it maintains current pressure drop, water loss, and size restrictions while increasing tolerance for pressure increases due to gas build-up in the trap.

  4. Design and Development of an air-cooled Temperature-Swing Adsorption Compressor for Carbon Dioxide

    NASA Technical Reports Server (NTRS)

    Mulloth, Lila M.

    2003-01-01

    The air revitalization system of the International Space Station (ISS) operates in an open loop mode and relies on the resupply of oxygen and other consumables from earth for the life support of astronauts. A compressor is required for delivering the carbon dioxide from a removal assembly to a reduction unit to recover oxygen and thereby closing the air-loop. We have a developed a temperature-swing adsorption compressor (TSAC) for performing these tasks that is energy efficient, quiet, and has no wearing parts. This paper discusses the design features of a TSAC hardware that uses air as the cooling medium and has Space Station application.

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

    PubMed

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

    2017-01-20

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

  6. Designing Scenarios for Controller-in-the-Loop Air Traffic Simulations

    NASA Technical Reports Server (NTRS)

    Kupfer, Michael; Mercer, Joey S.; Cabrall, Christopher; Callantine, Todd

    2013-01-01

    Well prepared traffic scenarios contribute greatly to the success of controller-in-the-loop simulations. This paper describes each stage in the design process of realistic scenarios based on real-world traffic, to be used in the Airspace Operations Laboratory for simulations within the Air Traffic Management Technology Demonstration 1 effort. The steps from the initial analysis of real-world traffic, to the editing of individual aircraft records in the scenario file, until the final testing of the scenarios before the simulation conduct, are all described. The iterative nature of the design process and the various efforts necessary to reach the required fidelity, as well as the applied design strategies, challenges, and tools used during this process are also discussed.

  7. Designing Scenarios for Controller-in-the-Loop Air Traffic Simulations

    NASA Technical Reports Server (NTRS)

    Kupfer, Michael; Mercer, Joey; Cabrall, Chris; Homola, Jeff; Callantine, Todd

    2013-01-01

    Within the Human Factors Division at NASA Ames Research Center the Airspace Operations Laboratory (AOL) is developing advanced automation concepts that help to transform the National Airspace System into NextGen, the Next Generation Air Transportation System. High-fidelity human-in-the-loop (HITL) simulations are used as a means to investigate and develop roles, responsibilities, support tools, and requirements for human operators and automation. This paper describes the traffic scenario design process and strategies as used by AOL researchers. Details are presented on building scenarios for specific simulation objectives using various design strategies. A focus is set on creating scenarios based on recorded real world traffic for terminal-area simulations.

  8. Trade Spaces in Crewed Spacecraft Atmosphere Revitalization System Development

    NASA Technical Reports Server (NTRS)

    Perry, Jay L.; Bagdigian, Robert M.; Carrasquillo, Robyn L.

    2010-01-01

    Developing the technological response to realizing an efficient atmosphere revitalization system for future crewed spacecraft and space habitats requires identifying and describing functional trade spaces. Mission concepts and requirements dictate the necessary functions; however, the combination and sequence of those functions possess significant flexibility. Us-ing a closed loop environmental control and life support (ECLS) system architecture as a starting basis, a functional unit operations approach is developed to identify trade spaces. Generalized technological responses to each trade space are discussed. Key performance parameters that apply to functional areas are described.

  9. Performance of an internal-loop airlift bioreactor for treatment of hexane-contaminated air.

    PubMed

    Oliveira, Fernando J S; de França, Francisca P

    2005-01-01

    Hexane is a toxic volatile organic compound that is quite abundant in gas emissions from chemical industries and printing press and painting centers, and it is necessary to treat these airstreams before they discharge into the atmosphere. This article presents a treatment for hexane-contaminated air in steady-state conditions using an internal-loop airlift bioreactor inoculated with a Pseudomonas aeruginosa strain. Bioprocesses were conducted at 20-mL/min, a load of 1.26 gm3 of C6H14, and a temperature of 28 degrees C. The results of hexane removal efficiencies were presented as a function of the inoculum size (approx 0.07 and 0.2 g/L) and cell reuse. Bioprocess monitoring comprises quantification of the biomass, the surface tension of the medium, and the hexane concentration in the fermentation medium as well as in the inlet and outlet airstreams. The steady-state results suggest that the variation in inoculum size from 0.07 to 0.2 g/L promotes hexane abatement from the influent from 65 to 85%, respectively. Total hydrocarbon removal from the waste gas was achieved during experiments conducted using reused cells at an initial microbial concentration of 0.2 g/L.

  10. Space Suit Environment Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Lin, Amy; Sweterlitsch, Jeffrey; Cox, Marlon

    2009-01-01

    An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Orion Atmosphere Revitalization System (ARS). In two previous years at this conference, reports were presented on extensive Johnson Space Center (JSC) testing of this technology in a sea-level pressure environment with simulated human metabolic loads. Another paper at this year s conference discusses similar testing with real human metabolic loads, including some closed-loop testing with emergency breathing masks. The Orion ARS is designed to also support extravehicular activity operations from a depressurized cabin. The next step in developmental testing at JSC was, therefore, to test this ARS technology in a typical closed space suit loop environment with low-pressure pure oxygen inside the process loop and vacuum outside the loop. This was the first instance of low-pressure oxygen loop testing of a new Orion ARS technology, and was conducted with simulated human metabolic loads in December 2008. The test investigated pressure drops through two different styles of prototype suit umbilical connectors and general swing-bed performance with both umbilical configurations as well as with a short jumper line installed in place of the umbilicals. Other interesting results include observations on the thermal effects of swing-bed operation in a vacuum environment and a recommendation of cycle time to maintain acceptable atmospheric CO2 and moisture levels.

  11. Space Suit Environment Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Button, Amy B.; Sweterlitsch, Jeffrey J.; Cox, Marlon R.

    2010-01-01

    An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Orion Atmosphere Revitalization System (ARS). In three previous years at this conference, reports were presented on extensive Johnson Space Center (JSC) testing of this technology. That testing was performed in a sea-level pressure environment with both simulated and real human metabolic loads, and in both open and closed-loop configurations. The Orion ARS is designed to also support space-suited operations in a depressurized cabin, so the next step in developmental testing at JSC was to test the ARS technology in a typical closed space suit-loop environment with low-pressure oxygen inside the process loop and vacuum outside the loop. This was the first instance of low-pressure, high-oxygen, closed-loop testing of the Orion ARS technology, and it was conducted with simulated human metabolic loads in March 2009. The test investigated pressure drops and flow balancing through two different styles of prototype suit umbilical connectors. General swing-bed performance was tested with both umbilical configurations, as well as with a short jumper line installed in place of the umbilicals. Other interesting results include observations on the thermal effects of swing-bed operation in a vacuum environment and a recommendation of cycle time to maintain acceptable suit atmospheric CO2 and moisture levels.

  12. Curriculum Revitalization Initiative at Tulane

    PubMed Central

    2015-01-01

    Tulane School of Public Health and Tropical Medicine launched its curriculum revitalization initiative to examine the Master of Public Health degrees (MPH). The initiative will enhance excellence in MPH education and incorporate innovative teaching approaches. Taskforces determined the MPH core should provide the foundation for public health, integrate knowledge across public health areas, and develop skills and methods needed in practice. The MPH is being updated to provide specialized study that builds skills and practical applications based on theory and evidence-based approaches. Eleven graduate certificates were developed to provide a second area of specialization. Practica are viewed as increasingly important for students without practical experience. Teaching methods will incorporate more technology including online modules for a blended classroom approach. PMID:25706011

  13. Evaluation of Cathode Air Flow Transients in a SOFC/GT Hybrid System Using Hardware in the Loop Simulation.

    PubMed

    Zhou, Nana; Yang, Chen; Tucker, David

    2015-02-01

    Thermal management in the fuel cell component of a direct fired solid oxide fuel cell gas turbine (SOFC/GT) hybrid power system can be improved by effective management and control of the cathode airflow. The disturbances of the cathode airflow were accomplished by diverting air around the fuel cell system through the manipulation of a hot-air bypass valve in open loop experiments, using a hardware-based simulation facility designed and built by the U.S. Department of Energy, National Energy Technology Laboratory (NETL). The dynamic responses of the fuel cell component and hardware component of the hybrid system were studied in this paper.

  14. Observed air-sea interactions in tropical cyclone Isaac over Loop Current mesoscale eddy features

    NASA Astrophysics Data System (ADS)

    Jaimes, Benjamin; Shay, Lynn K.; Brewster, Jodi K.

    2016-12-01

    Air-sea interactions during the intensification of tropical storm Isaac (2012) into a hurricane, over warm oceanic mesoscale eddy features, are investigated using airborne oceanographic and atmospheric profilers. Understanding these complex interactions is critical to correctly evaluating and predicting storm effects on marine and coastal facilities in the Gulf of Mexico, wind-driven mixing and transport of suspended matter throughout the water column, and oceanic feedbacks on storm intensity. Isaac strengthened as it moved over a Loop Current warm-core eddy (WCE) where sea surface warming (positive feedback mechanism) of ∼0.5 °C was measured over a 12-h interval. Enhanced bulk enthalpy fluxes were estimated during this intensification stage due to an increase in moisture disequilibrium between the ocean and atmosphere. These results support the hypothesis that enhanced buoyant forcing from the ocean is an important intensification mechanism in tropical cyclones over warm oceanic mesoscale eddy features. Larger values in equivalent potential temperature (θE = 365   ∘K) were measured inside the hurricane boundary layer (HBL) over the WCE, where the vertical shear in horizontal currents (δV) remained stable and the ensuing cooling vertical mixing was negligible; smaller values in θE (355   ∘K) were measured over an oceanic frontal cyclone, where vertical mixing and upper-ocean cooling were more intense due to instability development in δV . Thus, correctly representing oceanic mesoscale eddy features in coupled numerical models is important to accurately reproduce oceanic responses to tropical cyclone forcing, as well as the contrasting thermodynamic forcing of the HBL that often causes storm intensity fluctuations over these warm oceanic regimes.

  15. Revitalizing Inner-City Minority Communities

    ERIC Educational Resources Information Center

    Ikemma, William N.

    1977-01-01

    The black neighborhood based business environment in Houston, Texas, is examined as an example of minority community revitalization. A number of strategies for improving black community development in the nation's cities are suggested. (GC)

  16. Potential and benefits of closed loop ECLS systems on the ISS.

    PubMed

    Raatschen, W; Preiss, H

    2001-01-01

    To close open loops for long manned missions in space is a big challenge for aeronautic engineers throughout the world. The paper's focus is on the oxygen reclamation from carbon dioxide within a space habitat. A brief description of the function principle of a fixed alkaline electrolyzer, a solid amine carbon dioxide concentrator and a Sabatier reactor is given. By combining these devices to an air revitalization system the technical and economical benefits are explained. Astrium's Air Revitalization System (ARES) as a potential future part of the International Space Station's Environmental Control and Life Support System would close the oxygen loop. The amount of oxygen, needed for an ISS crew of seven astronauts could be provided by ARES. The upload of almost 1500 kg of water annually for oxygen generation through the onboard electrolyzer would be reduced by more than 1000 kg, resulting in savings of more than 30M$ per year. Additionally, the payload capacity of supply flights would be increased by this amount of mass. Further possibilities are addressed to combine ECLS mass flows with those of the power, propulsion and attitude control systems. Such closed loop approaches will contribute to ease long time missions (e. g. Mars, Moon) from a cost and logistic point of view. The hardware realization of Astrium's space-sized operating ARES is shown and test results of continuous and intermittent closed chamber tests are presented.

  17. Determination of the Clean Air Delivery Rate (CADR) of Photocatalytic Oxidation (PCO) Purifiers for Indoor Air Pollutants Using a Closed-Loop Reactor. Part I: Theoretical Considerations.

    PubMed

    Dumont, Éric; Héquet, Valérie

    2017-03-06

    This study demonstrated that a laboratory-scale recirculation closed-loop reactor can be an efficient technique for the determination of the Clean Air Delivery Rate (CADR) of PhotoCatalytic Oxidation (PCO) air purification devices. The recirculation closed-loop reactor was modeled by associating equations related to two ideal reactors: one is a perfectly mixed reservoir and the other is a plug flow system corresponding to the PCO device itself. Based on the assumption that the ratio between the residence time in the PCO device and the residence time in the reservoir τP/τR tends to 0, the model highlights that a lab closed-loop reactor can be a suitable technique for the determination of the efficiency of PCO devices. Moreover, if the single-pass removal efficiency is lower than 5% of the treated flow rate, the decrease in the pollutant concentration over time can be characterized by a first-order decay model in which the time constant is proportional to the CADR. The limits of the model are examined and reported in terms of operating conditions (experiment duration, ratio of residence times, and flow rate ranges).

  18. How utilizes can revitalize industry

    SciTech Connect

    De Vaul, D.; Bartsch, C.

    1993-12-31

    During the first weeks of his presidency, Bill Clinton asserted that the nation`s industries must modernize if Americans are to enjoy a rising standard of living. He noted that inadequate knowledge about new production technologies and inadequate capital for plant improvements were making it hard for manufacturers, particularly small and midsized firms, to improve their productivity and economic competitiveness. And though he said his administration would stress the benefits of government research, technology transfer, and financial assistance, President Clinton acknowledged that Washington needs new partners to help modernize U.S. industrial processes. Electric utilities are likely candidates. They have considerable technical expertise and access to large sums of capital that could help industry improve its productivity. Fortuitously, power companies also would benefit by such a partnership stimulating local economic activity and better managing electricity demands. Although many utilities pursue so-called demand-side management programs for their commercial and residential customers, most have not focused much attention on the industrial sector, in part because achieving industrial energy efficiency requires more specialized expertise than do routine energy audits to improve the insulation and lighting of homes and commercial buildings. Yet the reasons to target industry are compelling: Industrial firms consume more than 35 percent of the electricity in the United States, and investment in retooling manufacturing operations with energy-efficient and productive equipment could help spur economic revitalization.

  19. Determination of the Clean Air Delivery Rate (CADR) of Photocatalytic Oxidation (PCO) Purifiers for Indoor Air Pollutants Using a Closed-Loop Reactor. Part II: Experimental Results.

    PubMed

    Héquet, Valérie; Batault, Frédéric; Raillard, Cécile; Thévenet, Frédéric; Le Coq, Laurence; Dumont, Éric

    2017-03-06

    The performances of a laboratory PhotoCatalytic Oxidation (PCO) device were determined using a recirculation closed-loop pilot reactor. The closed-loop system was modeled by associating equations related to two ideal reactors: a perfectly mixed reservoir with a volume of VR = 0.42 m³ and a plug flow system corresponding to the PCO device with a volume of VP = 5.6 × 10(-3) m³. The PCO device was composed of a pleated photocatalytic filter (1100 cm²) and two 18-W UVA fluorescent tubes. The Clean Air Delivery Rate (CADR) of the apparatus was measured under different operating conditions. The influence of three operating parameters was investigated: (i) light irradiance I from 0.10 to 2.0 mW·cm(-2); (ii) air velocity v from 0.2 to 1.9 m·s(-1); and (iii) initial toluene concentration C₀ (200, 600, 1000 and 4700 ppbv). The results showed that the conditions needed to apply a first-order decay model to the experimental data (described in Part I) were fulfilled. The CADR values, ranging from 0.35 to 3.95 m³·h(-1), were mainly dependent on the light irradiance intensity. A square root influence of the light irradiance was observed. Although the CADR of the PCO device inserted in the closed-loop reactor did not theoretically depend on the flow rate (see Part I), the experimental results did not enable the confirmation of this prediction. The initial concentration was also a parameter influencing the CADR, as well as the toluene degradation rate. The maximum degradation rate rmax ranged from 342 to 4894 ppbv/h. Finally, this study evidenced that a recirculation closed-loop pilot could be used to develop a reliable standard test method to assess the effectiveness of PCO devices.

  20. SMARTE: HELPING COMMUNITIES OVERCOME OBSTACLES TO REVITALIZATION - JUNE 28, 2006

    EPA Science Inventory

    SMARTe (Sustainable Management Approaches and Revitalization Tools -electronic) is a web-based decision support tool being developed by the Office of Research and Development (ORD) in partnership with the Office of Brownfields Cleanup and Revitalization (OBCR), the Interstate Tec...

  1. SMARTE: HELPING COMMUNITIES EVALUATE REUSE OPTIONS AND OVERCOME REVITALIZATION OBSTACLES

    EPA Science Inventory

    SMARTe (Sustainable Management Approaches and Revitalization Tools electronic) is a web-based decision support tool being developed by the Office of Research and Development (ORD) in partnership with the Office of Brownfields and Land Revitalization (OBLR), the Interstate Techn...

  2. Revitalizing the Nuclear Weapons Enterprise

    DTIC Science & Technology

    2010-03-01

    units failing Nuclear Operational Readiness Inspections ( NORI ). In assessing the Air Force, the Schlesinger Task Force found a cause for these...all of the time. For example, the Air Force unit involved in the “Bent Spear” incident in 2007 had passed their NORI about 16 months earlier.52

  3. GET SMARTE: DECISION TOOLS TO REVITALIZE BROWNFIELDS

    EPA Science Inventory

    SMARTe (Sustainable Management Approaches and Revitalization Tools-electronic) is an open-source, web-based, decision-support system for developing and evaluating future use scenarios for potentially contaminated sites (i.e., brownfields). It contains resources and analysis tools...

  4. Learning Communities: A Paradigm for Educational Revitalization.

    ERIC Educational Resources Information Center

    Smith, Barbara Leigh; Hunter, M. Rosetta

    1988-01-01

    Describes a collaborative program initiated by Evergreen State College and Seattle Central Community College in Washington to promote faculty revitalization, curricular reform, and interinstitutional articulation. Examines the new curriculum of Seattle Central, as an intentionally designed "learning community," structured to sustain academic…

  5. Some Basics of Indigenous Language Revitalization.

    ERIC Educational Resources Information Center

    Reyhner, Jon

    Drawing from papers presented at the five "Stabilizing Indigenous Languages" symposia held since 1994, this paper recommends strategies for language revitalization at various stages of language loss. Based on a study of minority languages worldwide, Joshua Fishman postulated a continuum of eight stages of language loss, ranging from the…

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

  7. Open and Closed Loop Stability of Hingeless Rotor Helicopter Air and Ground Resonance

    NASA Technical Reports Server (NTRS)

    Young, M. I.; Bailey, D. J.; Hirschbein, M. S.

    1974-01-01

    The air and ground resonance instabilities of hingeless rotor helicopters are examined on a relatively broad parametric basis including the effects of blade tuning, virtual hinge locations, and blade hysteresis damping, as well as size and scale effects in the gross weight range from 5,000 to 48,000 pounds. A special case of a 72,000 pound helicopter air resonance instability is also included. The study shows that nominal to moderate and readily achieved levels of blade inertial hysteresis damping in conjunction with a variety of tuning and/or feedback conditions are highly effective in dealing with these instabilities. Tip weights and reductions in pre-coning angles are also shown to be effective means for improving the air resonance instability.

  8. First Human Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Lin, Amy; Sweterlitsch, Jeffrey

    2008-01-01

    An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Orion Atmosphere Revitalization System (ARS). In two previous years at this conference, reports were presented on extensive Johnson Space Center (JSC) testing of the technology in a representative environment with simulated human metabolic loads. The next step in developmental testing at JSC was to replace the simulated humans with real humans; this testing was conducted in the spring of 2008. This first instance of human testing of a new Orion ARS technology included several cases in a sealed Orione-quivalent free volume and three cases using emergency breathing masks connected directly to the ARS loop. Significant test results presented in this paper include comparisons between the standard metabolic rates for CO2 and water vapor production published in Orion requirements documents and real-world rate ranges observed with human test subjects. Also included are qualitative assessments of process flow rate and closed-loop pressure-cycling tolerability while using the emergency masks. Recommendations for modifications to the Orion ARS design and operation, based on the test results, conclude the paper.

  9. Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Button, Amy; Sweterlisch, Jeffery J.

    2013-01-01

    An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Atmosphere Revitalization System for moderate duration missions of the Orion Multipurpose Crew Vehicle. In previous years at this conference, reports were presented on extensive Johnson Space Center testing of this technology in a sea-level pressure environment with simulated and actual human metabolic loads in both open and closed-loop configurations. In 2011, the technology was tested in an open cabin-loop configuration at ambient and two sub-ambient pressures to compare the performance of the system to the results of previous tests at ambient pressure. The testing used a human metabolic simulator with a different type of water vapor generation than previously used, which added some unique challenges in the data analysis. This paper summarizes the results of: baseline and some matrix testing at all three cabin pressures, increased vacuum regeneration line pressure with a high metabolic load, a set of tests studying CO2 and water vapor co-adsorption effects relative to model-predicted performance, and validation tests of flight program computer model predictions with specific operating conditions.

  10. First Human Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Lin, Amy; Sweterlitsch, Jeffrey

    2009-01-01

    An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Orion Atmosphere Revitalization System (ARS). In two previous years at this conference, reports were presented on extensive Johnson Space Center (JSC) testing of the technology in a representative environment with simulated human metabolic loads. The next step in developmental testing at JSC was to replace the simulated humans with real humans; this testing was conducted in the spring of 2008. This first instance of human testing of a new Orion ARS technology included several cases in a sealed Orion-equivalent free volume and three cases using emergency breathing masks connected directly to the ARS loop. Significant test results presented in this paper include comparisons between the standard metabolic rates for CO2 and water vapor production published in Orion requirements documents and real-world rate ranges observed with human test subjects. Also included are qualitative assessments of process flow rate and closed-loop pressure-cycling tolerability while using the emergency masks. Recommendations for modifications to the Orion ARS design and operation, based on the test results, conclude the paper.

  11. Reduced Pressure Cabin Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Button, Amy B.; Sweterlitsch, Jeffrey J.

    2013-01-01

    An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by United Technologies Corp. Aerospace Systems (UTAS, formerly Hamilton Sundstrand) and baselined for the Atmosphere Revitalization System for moderate duration missions of the Orion Multipurpose Crew Vehicle (MPCV). In previous years at this conference, reports were presented on extensive Johnson Space Center testing of this technology in a sea-level pressure environment with simulated and actual human metabolic loads in both open and closed-loop configurations. In 2011, the technology was tested in an open cabin-loop configuration at ambient and two sub-ambient pressures to compare the performance of the system to the results of previous tests at ambient pressure. The testing used a human metabolic simulator with a different type of water vapor generation than previously used, which added some unique challenges in the data analysis. This paper summarizes the results of: baseline and some matrix testing at all three cabin pressures, increased vacuum regeneration line pressure testing with a high metabolic load, a set of tests studying CO2 and water vapor co-adsorption effects relative to model-predicted performance, and validation tests of flight project computer model predictions with specific operating conditions.

  12. Urban revitalization and displacement: types, causes, and public policy

    SciTech Connect

    Feagin, J.R.

    1981-05-01

    The policy research report reviews the scholarly and print media literatures on urban revitalization. The extent of revitalization; the incumbent or occupant upgrading; gentrification (displacement of low- and moderate-income households by better-off households); gentrification and displacement from all causes; and the role of powerful actors in revitalization are discussed. Public policy dealing with land use and development in urban areas is discussed. Future research needs are indicated.

  13. Ecological Revitalization: Turning Contaminated Properties Into Community Assets

    EPA Pesticide Factsheets

    This document provides technical information to assist property managers and other stakeholders better understand, coordinate, and conduct ecological revitalization at contaminated properties during cleanup

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  15. The Physical/Chemical Closed-Loop Life Support Research Project

    NASA Technical Reports Server (NTRS)

    Bilardo, Vincent J., Jr.

    1990-01-01

    The various elements of the Physical/Chemical Closed-Loop Life Support Research Project (P/C CLLS) are described including both those currently funded and those planned for implementation at ARC and other participating NASA field centers. The plan addresses the entire range of regenerative life support for Space Exploration Initiative mission needs, and focuses initially on achieving technology readiness for the Initial Lunar Outpost by 1995-97. Project elements include water reclamation, air revitalization, solid waste management, thermal and systems control, and systems integration. Current analysis estimates that each occupant of a space habitat will require a total of 32 kg/day of supplies to live and operate comfortably, while an ideal P/C CLLS system capable of 100 percent reclamation of air and water, but excluding recycling of solid wastes or foods, will reduce this requirement to 3.4 kg/day.

  16. 2009 Continued Testing of the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Button, Amy B.; Swerterlitsch, Jeffrey J.

    2010-01-01

    An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Orion Atmosphere Revitalization System (ARS). In three previous years at this conference, reports were presented on extensive Johnson Space Center (JSC) testing of this technology in a sea-level pressure environment, with simulated and real human metabolic loads, in both open and closed-loop configurations. The test article design was iterated a third time before the latest series of such tests, which was performed in the first half of 2009. The new design incorporates a canister configuration modification for overall unit compactness and reduced pressure drop, as well as a new process flow control valve that incorporates both compressed gas purge and dual-end vacuum desorption capabilities. This newest test article is very similar to the flight article designs. Baseline tests of the new unit were performed to compare its performance to that of the previous test articles. Testing of compressed gas purge operations helped refine launchpad operating condition recommendations developed in earlier testing. Operating conditions used in flight program computer models were tested to validate the model projections. Specific operating conditions that were recommended by the JSC test team based on past test results were also tested for validation. The effects of vacuum regeneration line pressure on resulting cabin conditions was studied for high metabolic load periods, and a maximum pressure is recommended

  17. Revitalizing the Small Town Mainstreet. Hard Times: Communities in Transition.

    ERIC Educational Resources Information Center

    Cook, Edward A.; Bentley, Marion T.

    Presenting a base of general information that local business people and government officials involved with downtown revitalization should be familiar with in order to understand the range of options available and factors that will influence the outcomes of any revitalization program, the paper summarizes current theories, trends, studies, and…

  18. 78 FR 69629 - Revitalization of the AM Radio Service

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-20

    ... COMMISSION 47 CFR Part 73 Revitalization of the AM Radio Service AGENCY: Federal Communications Commission... broadcast radio service, and to ease regulatory burdens on existing AM broadcasters. The Commission also solicits further comments and suggestions designed to foster the revitalization of the AM broadcast...

  19. Developments in Atmosphere Revitalization Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Kittredge, Kenneth; Xoker, Robert F.; Cummings, Ramona; Gomez, Carlos F.

    2012-01-01

    "NASA's Advanced Exploration Systems (AES) program is pioneering new approaches for rapidly developing prototype systems, demonstrating key capabilities, and validating operational concepts for future human missions beyond Earth orbit" (NASA 2012). These forays beyond the confines of earth's gravity will place unprecedented demands on launch systems. They must not only blast out of earth's gravity well as during the Apollo moon missions, but also launch the supplies needed to sustain a crew over longer periods for exploration missions beyond earth's moon. Thus all spacecraft systems, including those for the separation of metabolic carbon dioxide and water from a crewed vehicle, must be minimized with respect to mass, power, and volume. Emphasis is also placed on system robustness both to minimize replacement parts and ensure crew safety when a quick return to earth is not possible. Current efforts are focused on improving the current state-of-the-art systems utilizing fixed beds of sorbent pellets by evaluating structured sorbents, seeking more robust pelletized sorbents, and examining alternate bed configurations to improve system efficiency and reliability. These development efforts combine testing of sub-scale systems and multi-physics computer simulations to evaluate candidate approaches, select the best performing options, and optimize the configuration of the selected approach, which is then implemented in a full-scale integrated atmosphere revitalization test. This paper describes the development of atmosphere revitalization models and simulations. A companion paper discusses the hardware design and sorbent screening and characterization effort in support of the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project within the AES program.

  20. Modeling of Revitalization of Atmospheric Water

    NASA Technical Reports Server (NTRS)

    Coker, Robert; Knox, Jim

    2014-01-01

    The Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project was initiated in September of 2011 as part of the Advanced Exploration Systems (AES) program. Under the ARREM project, testing of sub-scale and full-scale systems has been combined with multiphysics computer simulations for evaluation and optimization of subsystem approaches. In particular, this paper describes the testing and modeling of the water desiccant subsystem of the carbon dioxide removal assembly (CDRA). The goal is a full system predictive model of CDRA to guide system optimization and development.

  1. Revitalization - an organizational program for the individual

    SciTech Connect

    Brewer, J.M.

    1983-07-01

    Progressive devitalization is a malady that afflicts many workers resulting in tremendous costs to organizations. This malady has long been recognized by management but little has been done to treat it. A new approach to the problem has been insitituted at Lawrence Livermore National Laboratory, in the form of a group program called Revitalization. Early results have been very encouraging. The program will continue to be designed and improved in the hope of bringing more productivity to the organization and self-esteem to the individual.

  2. An air-cooled Litz wire coil for measuring the high frequency hysteresis loops of magnetic samples--a useful setup for magnetic hyperthermia applications.

    PubMed

    Connord, V; Mehdaoui, B; Tan, R P; Carrey, J; Respaud, M

    2014-09-01

    A setup for measuring the high-frequency hysteresis loops of magnetic samples is described. An alternating magnetic field in the range 6-100 kHz with amplitude up to 80 mT is produced by a Litz wire coil. The latter is air-cooled using a forced-air approach so no water flow is required to run the setup. High-frequency hysteresis loops are measured using a system of pick-up coils and numerical integration of signals. Reproducible measurements are obtained in the frequency range of 6-56 kHz. Measurement examples on ferrite cylinders and on iron oxide nanoparticle ferrofluids are shown. Comparison with other measurement methods of the hysteresis loop area (complex susceptibility, quasi-static hysteresis loops, and calorific measurements) is provided and shows the coherency of the results obtained with this setup. This setup is well adapted to the magnetic characterization of colloidal solutions of magnetic nanoparticles for magnetic hyperthermia applications.

  3. Revitalization of Basic Business Education at All Instructional Levels. National Business Education Yearbook, No. 20.

    ERIC Educational Resources Information Center

    Jones, Eugene, Ed.

    This yearbook, consisting of 15 papers, deals with the revitalization of basic business education at all levels of instruction. The focus of the papers is on revitalizing basic business education in general, revitalizing the subject areas of basic business eudcation, revitalizing business education through instructional strategies, and…

  4. Brownfields Shifting Gears: Driving Toward Auto Sector Property Revitalization

    EPA Pesticide Factsheets

    This is an overview of community success stories. By building strong partnerships and setting priorities for recovery and revitalization, the public and private sectors are realizing a great deal of success in addressing idle industrial brownfields.

  5. Development And Evaluation Of Sustainability Criteria For Land Revitalization

    EPA Science Inventory

    Land revitalization offers the opportunity to reconsider the functional roles that individual land parcels can contribute to sustaining environmental systems. Although the ability of individual parcels to make these systems more resilient and move more toward sustainability may ...

  6. SMARTE: IMPROVING REVITALIZATION DECISIONS - PRESENTATION FOR ETV INTERNATIONAL FORUM

    EPA Science Inventory

    SMARTe (Sustainable Management Approaches and Revitalization Tools - electronic) is an open-source, web-based, decision-support system for developing and evaluating alternative reuse scenarios for potentially contaminated sites (e.g., brownfields). It is being developed collabora...

  7. Land Revitalization in Arkansas, Louisiana, New Mexico, Oklahoma, and Texas

    EPA Pesticide Factsheets

    Land Revitalization Program is focused on restoring land and other natural resources into sustainable community assets that maximize beneficial economic, ecological and social uses to ensure protection of human health and the environment.

  8. Brownfields Portfields: Charting a Course for Port Revitalization

    EPA Pesticide Factsheets

    The following case studies illustrate how the Pilot Port communities and the Portfields partnership are leveraging resources and promoting innovative approaches to invigorate and enhance local community revitalization efforts.

  9. Update: Partnership for the Revitalization of National Wind Tunnel Force Measurement Technology Capability

    NASA Technical Reports Server (NTRS)

    Rhew, Ray D.

    2010-01-01

    NASA's Aeronautics Test Program (ATP) chartered a team to examine the issues and risks associated with the lack of funding and focus on force measurement over the past several years, focusing specifically on strain-gage balances. NASA partnered with the U.S. Air Force's Arnold Engineering Development Center (AEDC) to exploit their combined capabilities and take a national level government view of the problem and established the National Force Measurement Technology Capability (NFMTC) project. This paper provides an update on the team's status for revitalizing the government's balance capability with respect to designing, fabricating, calibrating, and using the these critical measurement devices.

  10. LaRC 20-Year Center Revitalization Plan

    NASA Technical Reports Server (NTRS)

    Mangum, Cathy H.; Harris, Charles E.; Allen, Cheryl L.; Craft, Stephen J.; Hope, Drew J.; Kegelman, Jerome T.; Mastaler, Michael D; Weiser, Erik S.

    2012-01-01

    LaRC has developed a 20-Year Center Revitalization Plan. The objective of this plan is to assure that the center infrastructure is sustainable for the long-term and that the center will have the essential facilities and laboratories to execute the future NASA mission. The plan was developed by a centerwide team, VITAL, and was approved by the Center Leadership Council (CLC) in March 2012. The revitalization plan will be implemented through the Center Master Planning process.

  11. Regulative Loops, Step Loops and Task Loops

    ERIC Educational Resources Information Center

    VanLehn, Kurt

    2016-01-01

    This commentary suggests a generalization of the conception of the behavior of tutoring systems, which the target article characterized as having an outer loop that was executed once per task and an inner loop that was executed once per step of the task. A more general conception sees these two loops as instances of regulative loops, which…

  12. Integrated Testing of a 4-Bed Molecular Sieve, Air-Cooled Temperature Swing Adsorption Compressor, and Sabatier Engineering Development Unit

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Miller, Lee; Campbell, Melissa; Mulloth, Lila; Varghese, Mini

    2006-01-01

    Accumulation and subsequent compression of carbon dioxide that is removed from the space cabin are two important processes involved in a closed-loop air revitalization scheme of the International Space Station (ISS). The 4-Bed Molecular Sieve (4BMS) of ISS currently operates in an open loop mode without a compressor. The Sabatier Engineering Development Unit (EDU) processes waste CO2 to provide water to the crew. This paper reports the integrated 4BMS, air-cooled Temperature Swing Adsorption Compressor (TSAC), and Sabatier EDU testing. The TSAC prototype was developed at NASA Ames Research Center (ARC). The 4BMS was modified to a functionally flight-like condition at NASA Marshall Space Flight Center (MSFC). Testing was conducted at MSFC. The paper provides details of the TSAC operation at various CO2 loadings and corresponding performance of the 4BMS and Sabatier.

  13. The Orion Atmosphere Revitalization Technology in Manned Ambient Pressure Space Suit Testing

    NASA Technical Reports Server (NTRS)

    Button, Amy; Sweterlitsch, Jeffrey

    2011-01-01

    An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Atmosphere Revitalization System (ARS) for moderate duration missions of the Orion Multipurpose Crew Vehicle. The Orion ARS is designed to support not only open-cabin operations, tests of which have been reported in previous years at this conference, but also closed space suit-loop operations. A previous low-pressure suit loop test was performed with a human metabolic simulator, and humans wearing emergency masks were tested in a closed-loop configuration before that. In late 2011, simple tests were performed in a suit-loop configuration with human test subjects in prototype space suits with prototype umbilicals at ambient and two slightly above-ambient pressures. Trace contaminant filters and a prototype blower were also incorporated into the test rig. This paper discusses the performance of the ARS technology in that 2011 test configuration.

  14. Planning for Small Town Revitalization: Economic Development Invigorates the Columbia Basin.

    ERIC Educational Resources Information Center

    Winchell, Dick G.

    1991-01-01

    Describes rural revitalization efforts for small towns in central Washington. Planning analysis by Eastern Washington University faculty and students emphasizes community participation. Details revitalization of the town of Wilbur from planning stages to final outcomes. Describes overall project results. (KS)

  15. Death rate in a small air-lift loop reactor of vero cells grown on solid microcarriers and in macroporous microcarriers.

    PubMed

    Martens, D E; Nollen, E A; Hardeveld, M; van der Velden-de Groot, C A; de Gooijer, C D; Beuvery, E C; Tramper, J

    1996-01-01

    The death rate of Vero cells grown on Cytodex-3 microcarriers was studied as a function of the gas flow rate in a small air-lift loop reactor. The death rate may be described by first-order death-rate kinetics. The first-order death-rate constant as calculated from the decrease in viable cells, the increase in dead cells and the increase in LDH activity is linear proportional to the gas flow rate, with a specific hypothetical killing volume in which all cells are killed of about 2·10(-3) m(3) liquid per m(3) of air bubbles. In addition, an experiment was conducted in the same air-lift reactor with Vero cells grown inside porous Asahi microcarriers. The specific hypothetical killing volume calculated from this experiment has a value of 3·10(-4) m(3) liquid per m(3) of air bubbles, which shows that the porous microcarriers were at least in part able to protect the cells against the detrimental hydrodynamic forces generated by the bubbles.

  16. Air Re-Vitalization System Development for Closed Ecological System

    NASA Astrophysics Data System (ADS)

    Sakurai, Masato

    Japan has effectively and efficiently accumulated technologies required for human space activities through its participation in the International Space Station (ISS) program. After the completion of the ISS program, the main arena of human space activities could move from low- Earth orbit to the Moon in the future. In preparation for such development, JAXA considers a future "international human lunar base" that might be developed as the place where Japan could fully utilize, maintain and further develop its capability for conducting human space activities. Since the moon is a test-bed for Mars, permanent lunar bases are a logical outgrowth of initial lunar exploration. For brief visits, the lunar base requires only stored oxygen and water, but a permanent lunar base must recycle oxygen and water to reduce transportation costs. This kind activities will give a great suggestion to sustainable society. A conceptual model of a life support system using physicochemical treatment to circulate the material has been designed. This paper describes test results of the significant design features and preliminary test results of the oxygen production system. The 0.04-0.2

  17. Effects of Cabin Upsets on Adsorption Columns for Air Revitalization

    NASA Technical Reports Server (NTRS)

    LeVan, M. Douglas

    1999-01-01

    The National Aeronautics and Space Administration (NASA) utilizes adsorption technology as part of contaminant removal systems designed for long term missions. A variety of trace contaminants can be effectively removed from gas streams by adsorption onto activated carbon. An activated carbon adsorption column meets NASA's requirements of a lightweight and efficient means of controlling trace contaminant levels aboard spacecraft and space stations. The activated carbon bed is part of the Trace Contaminant Control System (TCCS) which is utilized to purify the cabin atmosphere. TCCS designs oversize the adsorption columns to account for irregular fluctuations in cabin atmospheric conditions. Variations in the cabin atmosphere include changes in contaminant concentrations, temperature, and relative humidity. Excessively large deviations from typical conditions can result from unusual crew activity, equipment malfunctions, or even fires. The research carried out under this award focussed in detail on the effects of cabin upsets on the performance of activated carbon adsorption columns. Both experiments and modeling were performed with an emphasis on the roll of a change in relative humidity on adsorption of trace contaminants. A flow through fixed-bed apparatus was constructed at the NASA Ames Research Center, and experiments were performed there by W. Scot Appel under the direction of Dr. John E. Finn. Modeling work was performed at the University of Virginia and at Vanderbilt University by W. Scot Appel under the direction of M. Douglas LeVan. All three participants collaborated in all of the various phases of the research. The most comprehensive document describing the research is the Ph.D. dissertation of W. Scot Appel. Results have been published in several papers and presented in talks at technical conferences. All documents have been transmitted to Dr. John E. Finn.

  18. Effects of Cabin Upsets on Adsorption Columns for Air Revitalization

    NASA Technical Reports Server (NTRS)

    LeVan, Douglas

    1999-01-01

    The National Aeronautics and Space Administration (NASA) utilizes adsorption technology as part of contaminant removal systems designed for long term missions. A variety of trace contaminants can be effectively removed from gas streams by adsorption onto activated carbon. An activated carbon adsorption column meets NASA's requirements of a lightweight and efficient means of controlling trace contaminant levels aboard spacecraft and space stations. The activated carbon bed is part of the Trace Contaminant Control System (TCCS) which is utilized to purify the cabin atmosphere. TCCS designs oversize the adsorption columns to account for irregular fluctuations in cabin atmospheric conditions. Variations in the cabin atmosphere include changes in contaminant concentrations, temperature, and relative humidity. Excessively large deviations from typical conditions can result from unusual crew activity, equipment malfunctions, or even fires. The research carried out under this award focussed in detail on the effects of cabin upsets on the performance of activated carbon adsorption columns. Both experiments and modeling were performed with an emphasis on the roll of a change in relative humidity on adsorption of trace contaminants. A flow through fixed-bed apparatus was constructed at the NASA Ames Research Center, and experiments were performed there. Modeling work was performed at the University of Virginia.

  19. Trace Contaminant Testing with the Orion Atmosphere Revitalization Technology

    NASA Technical Reports Server (NTRS)

    Button, Amy B.; Sweterlitsch, Jeffrey J.; Broerman, Craig D.; Campbell, Melissa L.

    2010-01-01

    Every spacecraft atmosphere contains trace contaminants resulting from offgassing by cabin materials and human passengers. An amine-based carbon dioxide (CO2) and water vapor sorbent in pressure-swing regenerable beds has been developed by Hamilton Sundstrand and baselined for the Orion Atmosphere Revitalization System (ARS). Part of the risk mitigation effort for this new technology is the study of how atmospheric trace contaminants will affect and be affected by the technology. One particular area of concern is ammonia, which, in addition to the normal spacecraft sources, can also be offgassed by the amine-based sorbent. In the spring of 2009, tests were performed at Johnson Space Center (JSC) with typical cabin atmosphere levels of five of the most common trace gases, most of which had not yet been tested with this technology. A subscale sample of the sorbent was exposed to each of the chemicals mixed into a stream of moist, CO2-laden air, and the CO2 adsorption capacity of the sorbent was compared before and after the exposure. After these typical-concentration chemicals were proven to have negligible effect on the subscale sample, tests proceeded on a full-scale test article in a sealed chamber with a suite of eleven contaminants. To isolate the effects of various test rig components, several extended-duration tests were run: without injection or scrubbing, with injection and without scrubbing, with injection of both contaminants and metabolic CO2 and water vapor loads and scrubbing by both the test article and dedicated trace contaminant filters, and with the same injections and scrubbing by only the test article. The high-level results of both the subscale and full-scale tests are examined in this paper.

  20. Development and Testing of a Sorbent-Based Atmosphere Revitalization System 2010/2011

    NASA Technical Reports Server (NTRS)

    Miller, Lee A.; Knox, James C.

    2012-01-01

    Spacecraft being developed for future exploration missions incorporate Environmental Control and Life Support Systems (ECLSS) that limit weight, power, and volume thus requiring systems with higher levels of efficiency while maintaining high dependability and robustness. For air revitalization, an approach that meets those goals utilizes a regenerative Vacuum-Swing Adsorption (VSA) system that removes 100% of the CO2 from the cabin atmosphere as well as 100% of the water. A Sorbent Based Atmosphere Revitalization (SBAR) system is a VSA system that utilizes standard commercial adsorbents that have been proven effective and safe in spacecraft including Skylab and the International Space Station. The SBAR system is the subject of a development, test, and evaluation program that is being conducted at NASA s Marshall Space Flight Center. While previous testing had validated that the technology is a viable option, potential improvements to system design and operation were identified. Modifications of the full-scale SBAR test articles and adsorption cycles have been implemented and have shown significant performance gains resulting in a decrease in the consumables required for a mission as well as improved mission safety. Previous testing had utilized single bed test articles, during this period the test facility was enhanced to allow testing on the full 2-bed SBAR system. The test facility simulates a spacecraft ECLSS and allows testing of the SBAR system over the full range of operational conditions using mission simulations that assess the real-time performance of the SBAR system during scenarios that include the metabolic transients associated with extravehicular activity. Although future manned missions are currently being redefined, the atmosphere revitalization requirements for the spacecraft are expected to be quite similar to the Orion and the Altair vehicles and the SBAR test program addressed validation to the defined mission requirements as well as operation

  1. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  2. Loop quantization

    SciTech Connect

    Nicolau, A.

    1988-10-01

    Loop unwinding is a known technique for reducing loop overhead, exposing parallelism, and increasing the efficiency of pipelining. Traditional loop unwinding is limited to the innermost loop in a group of nested loops and the amount of unwinding either is fixed or must be specified by the user, on a case by case basis. In this paper the authors present a general technique for automatically unwinding multiply nested loops, explain its advantages over other transformation techniques, and illustrate its practical effectiveness. Lopp Quantization could be beneficial by itself or coupled with other loop transformations.

  3. Reshaping Curricula: Revitalization Programs at Three Land Grant Universities.

    ERIC Educational Resources Information Center

    Lunde, Joyce Povlacs; And Others

    This volume contains 25 papers describing large curriculum revitalization projects from 1986 through 1991 at the University of Wisconsin-Madison, the University of Minnesota, and the University of Nebraska-Lincoln. The papers are: "A Theoretical Context for Designing Curricula in the Agricultural and Life Sciences" (Robert G. Kranz,…

  4. Language Revitalization and Language Pedagogy: New Teaching and Learning Strategies

    ERIC Educational Resources Information Center

    Hinton, Leanne

    2011-01-01

    Language learning and teaching of endangered languages have many features and needs that are quite different from the teaching of world languages. Groups whose languages are endangered try to turn language loss around; many new language teaching and learning strategies are emerging, to suit the special needs and goals of language revitalization.…

  5. GET SMARTE: DECISION TOOLS TO REVITALIZE COMMUNITIES (MAY 2006)

    EPA Science Inventory

    SMARTe (Sustainable Management Approaches and Revitalization Tools-electronic) is an open-source, web-based, decision-support system for developing and evaluating future use scenarios for potentially contaminated sites (i.e., brownfields). It contains resources and analysis tools...

  6. Urban Revitalization and Entrepreneurial Strategies. Digest Number 97-8.

    ERIC Educational Resources Information Center

    Schuyler, Gwyer

    Urban revitalization is an economic and social strategy that has been necessitated by decreased interest in both residence and commercialization within major cities. Urban business environments are confronted with many unique socioeconomic challenges, including discrimination against residents, negative stereotypes of urban areas, and inaccurate…

  7. Cultivating Common Ground: Cultural Revitalization in Anishinaabe and Anthropological Discourse

    ERIC Educational Resources Information Center

    Willow, Anna J.

    2010-01-01

    In this article, the author explores some of the most prominent ways that cultural revitalization has been contemplated within Anishinaabe and anthropological arenas of discourse. She draws reflexively on her own personal positionality and academic theoretical background as well as on her observations of how Anishinaabe anti-clear-cutting…

  8. SMARTE: IMPROVING REVITALIZATION DECISIONS - PRESENTATION IN NRMRL SEMINAR SERIES

    EPA Science Inventory

    SMARTe (Sustainable Management Approaches and Revitalization Tools-electribuc) is an open-source, web-based, decision-support system for developing and evaluating alternative reuse scenarios for potentially contaminated sites (e.g., brownfields). It is being developed collaborati...

  9. Ojibwe Language Revitalization, Multimedia Technology, and Family Language Learning

    ERIC Educational Resources Information Center

    Hermes, Mary; King, Kendall A.

    2013-01-01

    Although Indigenous language loss and revitalization are not new topics of academic work nor new areas of community activism (e.g., King, 2001; Grenoble & Whaley, 2006), increased attention has been paid in recent years to the ways that new technology can support efforts to teach and renew endangered languages such as Ojibwe. However, much of…

  10. Toward a New Era: Alternatives for Revitalizing Student Services Programs.

    ERIC Educational Resources Information Center

    Deegan, William L.

    Alternatives for revitalizing the programs and management of student services in community colleges are reviewed in this paper. First, alternatives related to student services programs are considered, including: (1) the increased use of computer-assisted counseling to integrate student services more fully with mainstream academic activities; (2)…

  11. Literacy for Revitalization in the SADCC Countries of Southern Africa.

    ERIC Educational Resources Information Center

    Bhola, H. S.

    The role of literacy in the revitalization of societies is particularly meaningful in the context of the Southern African Development Coordination Conference (SADCC), a group of nine countries (Angola, Botswana, Lesotho, Malawi, Mozambique, Swaziland, Tanzania, Zambia, and Zimbabwe) surrounding or surrounded by the Republic of South Africa (RSA).…

  12. Indigenous Language Revitalization, Promotion, and Education: Function of Digital Technology

    ERIC Educational Resources Information Center

    Galla, Candace Kaleimamoowahinekapu

    2016-01-01

    Within the last two decades, there has been increased interest in how technology supports Indigenous language revitalization and reclamation efforts. This paper considers the effect technology has on Indigenous language learning and teaching, while conceptualizing how language educators, speakers, learners, and technology users holistically…

  13. The Green Book of Language Revitalization in Practice.

    ERIC Educational Resources Information Center

    Hinton, Leanne, Ed.; Hale, Ken, Ed.

    Essays in this book include the following: "Language Revitalization: An Overview" (Leanne Hinton); "Diversity in Local Language Maintenance and Restoration: A Reason for Optimism" (Anna Ash, Jessie Little Doe Fermino, Ken Hale); "Federal Language Policy and Indigenous Languages in the United States" (Leanne Hinton);…

  14. Death rate in a small air-lift loop reactor of vero cells grown on solid microcarriers and in macroporous microcarriers.

    PubMed

    Martens, D E; Nollen, E A; Hardeveld, M; Velden-de Groot, C A; Gooijer, C D; Beuvery, E C; Tramper, J

    1997-01-01

    The death rate of Vero cells grown on Cytodex-3 microcarrierswas studied as a function of the gas flow rate in a smallair-lift loop reactor. The death rate may be described byfirst-order death-rate kinetics. The first-order death-rateconstant as calculated from the decrease in viable cells, theincrease in dead cells and the increase in LDH activity islinear proportional to the gas flow rate, with a specifichypothetical killing volume in which all cells are killed ofabout 2.10(-3)m(3) liquid per m(3) of air bubbles.In addition, an experiment was conducted in the sameair-lift reactor with Vero cells grown inside porous Asahimicrocarriers. The specific hypothetical killing volumecalculated from this experiment has a value of 3.10(-4)m(3) liquid per m(3) of air bubbles, which shows thatthe porous microcarriers were at least in part able to protectthe cells against the detrimental hydrodynamic forcesgenerated by the bubbles.

  15. Development of an algorithm to regulate pump output for a closed air-loop type pneumatic biventricular assist device.

    PubMed

    Nam, Kyoung Won; Lee, Jung Joo; Hwang, Chang Mo; Choi, Jaesoon; Choi, Hyuk; Choi, Seong Wook; Sun, Kyung

    2009-12-01

    The closed air space-type of extracorporeal pneumatic ventricular assist device (VAD) developed by the Korea Artificial Organ Center utilizes a bellows-transforming mechanism to generate the air pressure required to pump blood. This operating mechanism can reduce the size and weight of the driving unit; however, the output of the blood pump can be affected by the pressure loading conditions of the blood sac. Therefore, to guarantee a proper pump output level, regardless of the pressure loading conditions that vary over time, automatic pump output regulation of the blood pump is required. We describe herein a pump output regulation algorithm that was developed to maintain pump output around a reference level against various afterload pressures, and verified the pump performance in vitro. Based on actual operating conditions in animal experiments, the pumping rate was limited to 40-84 beats per minute, and the afterload pressure was limited to 80-150 mm Hg. The tested reference pump output was 4.0 L/min. During experiments, the pump output was successfully and automatically regulated within the preset area regardless of the varying afterload conditions. The results of this preliminary experiment can be used as the basis for an automatic control algorithm that can enhance the stability and reliability of the applied VAD.

  16. Clearing the Air: New Approaches to Life Support in Outer Space

    NASA Technical Reports Server (NTRS)

    Knox, J.; Howard, D.

    2008-01-01

    This article reports on research into atmospheric revitalization systems for long-term space travel and the use ofCOMSOL Multiphysics to understand how structured sorbents can be used to improve the performance of adsorption processes via thermal management. We are developing the next generation of atmosphere revitalization systems, which will reach for new levels of resource conservation via a high percentage of loop closure. For example, a high percentage of carbon dioxide, exhaled by crew, can be converted via reaction to drinking water, closing the loop from human metabolic waste to supply. Adsorption processes play a lead role in these new/closed loop systems.

  17. Using Pyrolysis and its Bioproducts to Help Close the Loop in Sustainable Life Support Systems

    NASA Technical Reports Server (NTRS)

    McCoy, LaShelle E.

    2012-01-01

    The next step in human exploration of space is beyond low Earth orbit and possibly to sites such as the Moon and Mars. Resupply of critical life support components for missions such as these are difficult or impossible. Life support processes for closing the loop of water, oxygen and carbon have to be identified .. Currently, there are many technologies proposed for terrestrial missions for waste, water, air processing and the creation of consumables. There are a variety of different approaches, but few address all of these issues simultaneously. One candidate is pyrolysis; a method where waste streams can be heated in the absence of oxygen to undergo a thermochemical conversion producing a series of bioproducts. Bioproducts like biochar made from non-edible biomass and human solid waste can possibly provide valuable benefits such as waste reduction, regolith fertilization for increased food production, and become a consumable for water processing and air revitalization systems. Syngas containing hydrogen, carbon monoxide and cbon dioxide, can be converted to methane and dimethyl ether to create propellants. Bio-oils can be utilized as a heating fuel or fed to bioreactors that utilize oil-eating microbes. Issues such as carbon sequestration and subsequent carbon balance of the closed system and identifying ideal process methods to achieve the highest quality products, whilst being energy friendly, will also be addressed.

  18. Air Systems Provide Life Support to Miners

    NASA Technical Reports Server (NTRS)

    2014-01-01

    Through a Space Act Agreement with Johnson Space Center, Paragon Space Development Corporation, of Tucson, Arizona, developed the Commercial Crew Transport-Air Revitalization System, designed to provide clean air for crewmembers on short-duration space flights. The technology is now being used to help save miners' lives in the event of an underground disaster.

  19. Methane Post-Processing for Oxygen Loop Closure

    NASA Technical Reports Server (NTRS)

    Greenwood, Zachary W.; Abney, Morgan B.; Miller, Lee

    2016-01-01

    State-of-the-art United States Atmospheric Revitalization carbon dioxide (CO2) reduction is based on the Sabatier reaction process, which recovers approximately 50% of the oxygen (O2) from crew metabolic CO2. Oxygen recovery from carbon dioxide is constrained by the limited availability of reactant hydrogen. Post-processing of methane to recover hydrogen with the Umpqua Research Company Plasma Pyrolysis Assembly (PPA) has the potential to further close the Atmospheric Revitalization oxygen loop. The PPA decomposes methane into hydrogen and hydrocarbons, predominantly acetylene, and a small amount of solid carbon. The hydrogen must then be purified before it can be recycled for additional oxygen recovery. Long duration testing and evaluation of a four crew-member sized PPA and a discussion of hydrogen recycling system architectures are presented.

  20. Rethinking Community-Based Indigenous Language Revitalization Using Cultural-Historical Activity Theory

    ERIC Educational Resources Information Center

    Lin, Man-Chiu Amay; Yudaw, Bowtung

    2013-01-01

    This article suggests a theoretical framework for re-examining the complex relationship of language, literacy, and cultural practices, across multiple generations in the context of community-based Indigenous language revitalization. In the scholarship of Indigenous language revitalization and education, researchers have shifted from viewing…

  1. Learning Needs Analysis of Collaborative E-Classes in Semi-Formal Settings: The REVIT Example

    ERIC Educational Resources Information Center

    Mavroudi, Anna; Hadzilacos, Thanasis

    2013-01-01

    Analysis, the first phase of the typical instructional design process, is often downplayed. This paper focuses on the analysis concerning a series of e-courses for collaborative adult education in semi-formal settings by reporting and generalizing results from the REVIT project. REVIT, an EU-funded research project, offered custom e-courses to…

  2. Objectives at the Crossroads: Critical Theory and Self-Determination in Indigenous Language Revitalization

    ERIC Educational Resources Information Center

    Albury, Nathan John

    2015-01-01

    Indigenous language revitalization is a popular focus of critical theorists. From the perspective of sociolinguists, critical theory interrogates language policies to name and shame inequalities and propose solutions to correct injustices and emancipate the disadvantaged. From a broader perspective, language revitalization policy also resides…

  3. 77 FR 16251 - Announcement of Funding Awards, HOPE VI Revitalization Grant Program, Fiscal Year 2010

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-20

    ... URBAN DEVELOPMENT Announcement of Funding Awards, HOPE VI Revitalization Grant Program, Fiscal Year 2010... funding awards. SUMMARY: In accordance with Section 102(a)(4)(C) of the Department of Housing and Urban..., contact Ms. Susan Wilson, Director, Office of Urban Revitalization, Office of Public and Indian...

  4. From Documenting to Revitalizing an Endangered Language: Where Do Applied Linguists Fit?

    ERIC Educational Resources Information Center

    Penfield, Susan D.; Tucker, Benjamin V.

    2011-01-01

    This paper explores the distance between documenting and revitalizing endangered languages and indicates critical points at which applied linguistics can play a role. We look at language documentation, language revitalization and their relationship. We then provide some examples from our own work. We see the lack of applied linguistics as a…

  5. 75 FR 71137 - Announcement of Funding Awards for the HOPE VI Revitalization Grant Program for Fiscal Year 2009

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-22

    ... URBAN DEVELOPMENT Announcement of Funding Awards for the HOPE VI Revitalization Grant Program for Fiscal... Funding Availability (NOFA) for the HOPE VI Revitalization grant program. This announcement contains the... concerning the HOPE VI Revitalization grant awards, contact the Ms. Leigh van Rij, Office of Public...

  6. Challenges in the development of the orbiter atmosphere revitalization subsystem

    NASA Technical Reports Server (NTRS)

    Prince, R. N.; Swider, J.; Wojnarowski, J.; Decrisantis, A.; Ord, G. R.; Walleshauser, J. J.; Gibb, J. W.

    1985-01-01

    The space shuttle orbiter atmospheric revitalization subsystem provides thermal and contaminant control as well as total- and oxygen partial-pressure control of the environment within the orbiter crew cabin. Challenges that occurred during the development of this subsystem for the space shuttle orbiter are described. The design of the rotating hardware elements of the system (pumps, fans, etc.) required significant development to meet the requirements of long service life, maintainability, and high cycle-fatigue life. As a result, a stringent development program, particularly in the areas of bearing life and heat dissipation, was required. Another area requiring significant development was cabin humidity control and condensate collection.

  7. Vapor compression distiller and membrane technology for water revitalization

    NASA Technical Reports Server (NTRS)

    Ashida, A.; Mitani, K.; Ebara, K.; Kurokawa, H.; Sawada, I.; Kashiwagi, H.; Tsuji, T.; Hayashi, S.; Otsubo, K.; Nitta, K.

    1987-01-01

    Water revitalization for a space station can consist of membrane filtration processes and a distillation process. Water recycling equipment using membrane filtration processes was manufactured for ground testing. It was assembled using commercially available components. Two systems for the distillation are studied: one is absorption type thermopervaporation cell and the other is a vapor compression distiller. Absorption type thermopervaporation, able to easily produce condensed water under zero gravity, was investigated experimentally and through simulated calculation. The vapor compression distiller was studied experimentally and it offers significant energy savings for evaporation of water.

  8. The revitalization of the Public Health Service Commissioned Corps.

    PubMed

    Koop, C E; Ginzburg, H M

    1989-01-01

    The Public Health Service (PHS) is the second oldest uniformed service of the United States; its tradition commenced with the establishment of the Marine Hospital Service in 1798. Congress, in 1889, established the United States Public Health Service Commissioned Corps under the aegis of the Treasury. The Corps was created as a uniformed nonmilitary service with a distinct uniform, insignia, and with titles, pay, and retirement protocols that corresponded to those of the uniformed military services (the Armed Forces). Initially the health care system of the country, and Commissioned Corps members, were concerned with infectious and vitamin-deficiency diseases; more recently the nation's medical community has focused on cardiovascular diseases, cancer, and AIDS. A comprehensive revitalization of the Commissioned Corps began in April 1987. The intent was to restore the Commissioned Corps to its traditional leadership role as a cadre of mobile, compassionate experts ensuring the nation's health. The revitalization activities have been successful. The Commissioned Corps has approximately 5,500 active duty officers. The Surgeon General directed the development of career tracks for 11 categories of commissioned officers to increase the opportunities for professional development within the PHS and thus increase retention and professional growth. The theme for the 1989 celebration of the centennial of the Commissioned Corps is "a century of service with distinction." A hundred years from now, at the bicentennial of the Commissioned Corps, the current Surgeon General would like it to be said that the Public Health Service has had "two centuries of service with distinction."

  9. Additional Developments in Atmosphere Revitalization Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Coker, Robert F.; Knox, James C.; Cummings, Ramona; Brooks, Thomas; Schunk, Richard G.; Gomez, Carlos

    2013-01-01

    NASA's Advanced Exploration Systems (AES) program is developing prototype systems, demonstrating key capabilities, and validating operational concepts for future human missions beyond Earth orbit. These forays beyond the confines of earth's gravity will place unprecedented demands on launch systems. They must launch the supplies needed to sustain a crew over longer periods for exploration missions beyond earth's moon. Thus all spacecraft systems, including those for the separation of metabolic carbon dioxide and water from a crewed vehicle, must be minimized with respect to mass, power, and volume. Emphasis is also placed on system robustness both to minimize replacement parts and ensure crew safety when a quick return to earth is not possible. Current efforts are focused on improving the current state-of-the-art systems utilizing fixed beds of sorbent pellets by evaluating structured sorbents, seeking more robust pelletized sorbents, and examining alternate bed configurations to improve system efficiency and reliability. These development efforts combine testing of sub-scale systems and multi-physics computer simulations to evaluate candidate approaches, select the best performing options, and optimize the configuration of the selected approach. This paper describes the continuing development of atmosphere revitalization models and simulations in support of the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project within the AES program.

  10. URBAN REVITALIZATION AND SEATTLE CRIME, 1982-2000.

    PubMed

    Kreager, Derek A; Lyons, Christopher J; Hays, Zachary R

    2011-11-01

    This study examines the relationship between crime and processes of urban revitalization, or gentrification. Drawing on recent urban demography research, we hypothesize that gentrification progressed rapidly in many American cities over the last decade of the 20(th) century, and that these changes had implications for area crime rates. Criminological theories hold competing hypotheses for the connections between gentrification and crime, and quantitative studies of this link remain infrequent and limited. Using two measures of gentrification and longitudinal tract-level demographic and crime data for the city of Seattle, we find that many of Seattle's downtown tracts underwent rapid revitalization during the 1990's, and that these areas 1) saw reductions in crime relative to similar tracts that did not gentrify, and 2) were areas with higher-than-average crime at the beginning of the decade. Moreover, using a within-tract longitudinal design, we find that yearly housing investments in the 1980's showed a modest positive association with crime change, while yearly investments in the 1990's showed the opposite pattern. Our findings suggest a curvilinear gentrification-crime relationship, whereby gentrification in its earlier stages is associated with small increases in crime, but gentrification in its more consolidated form is associated with modest crime declines. Implications of these results for criminological theory, urban development, and broader crime patterns are discussed.

  11. Revitalization of the NASA Langley Research Center's Infrastructure

    NASA Technical Reports Server (NTRS)

    Weiser, Erik S.; Mastaler, Michael D.; Craft, Stephen J.; Kegelman, Jerome T.; Hope, Drew J.; Mangum, Cathy H.

    2012-01-01

    The NASA Langley Research Center (Langley) was founded in 1917 as the nation's first civilian aeronautical research facility and NASA's first field center. For nearly 100 years, Langley has made significant contributions to the Aeronautics, Space Exploration, and Earth Science missions through research, technology, and engineering core competencies in aerosciences, materials, structures, the characterization of earth and planetary atmospheres and, more recently, in technologies associated with entry, descent, and landing. An unfortunate but inevitable outcome of this rich history is an aging infrastructure where the longest serving building is close to 80 years old and the average building age is 44 years old. In the current environment, the continued operation and maintenance of this aging and often inefficient infrastructure presents a real challenge to Center leadership in the trade space of sustaining infrastructure versus not investing in future capabilities. To address this issue, the Center has developed a forward looking revitalization strategy that ties future core competencies and technical capabilities to the Center Master Facility Plan to maintain a viable Center well into the future. This paper documents Langley's revitalization strategy which integrates the Center's missions, the Langley 2050 vision, the Center Master Facility Plan, and the New Town repair-by-replacement program through the leadership of the Vibrant Transformation to Advance Langley (ViTAL) Team.

  12. URBAN REVITALIZATION AND SEATTLE CRIME, 1982–2000

    PubMed Central

    Kreager, Derek A.; Lyons, Christopher J.; Hays, Zachary R.

    2014-01-01

    This study examines the relationship between crime and processes of urban revitalization, or gentrification. Drawing on recent urban demography research, we hypothesize that gentrification progressed rapidly in many American cities over the last decade of the 20th century, and that these changes had implications for area crime rates. Criminological theories hold competing hypotheses for the connections between gentrification and crime, and quantitative studies of this link remain infrequent and limited. Using two measures of gentrification and longitudinal tract-level demographic and crime data for the city of Seattle, we find that many of Seattle’s downtown tracts underwent rapid revitalization during the 1990’s, and that these areas 1) saw reductions in crime relative to similar tracts that did not gentrify, and 2) were areas with higher-than-average crime at the beginning of the decade. Moreover, using a within-tract longitudinal design, we find that yearly housing investments in the 1980’s showed a modest positive association with crime change, while yearly investments in the 1990’s showed the opposite pattern. Our findings suggest a curvilinear gentrification-crime relationship, whereby gentrification in its earlier stages is associated with small increases in crime, but gentrification in its more consolidated form is associated with modest crime declines. Implications of these results for criminological theory, urban development, and broader crime patterns are discussed. PMID:25505350

  13. Additional Developments in Atmosphere Revitalization Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Coker, Robert F.; Knox, James C.; Cummings, Ramona; Brooks, Thomas; Schunk, Richard G.

    2013-01-01

    NASA's Advanced Exploration Systems (AES) program is developing prototype systems, demonstrating key capabilities, and validating operational concepts for future human missions beyond Earth orbit. These forays beyond the confines of earth's gravity will place unprecedented demands on launch systems. They must launch the supplies needed to sustain a crew over longer periods for exploration missions beyond earth's moon. Thus all spacecraft systems, including those for the separation of metabolic carbon dioxide and water from a crewed vehicle, must be minimized with respect to mass, power, and volume. Emphasis is also placed on system robustness both to minimize replacement parts and ensure crew safety when a quick return to earth is not possible. Current efforts are focused on improving the current state-of-the-art systems utilizing fixed beds of sorbent pellets by evaluating structured sorbents, seeking more robust pelletized sorbents, and examining alternate bed configurations to improve system efficiency and reliability. These development efforts combine testing of sub-scale systems and multi-physics computer simulations to evaluate candidate approaches, select the best performing options, and optimize the configuration of the selected approach. This paper describes the continuing development of atmosphere revitalization models and simulations in support of the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM)

  14. Revitalizing Indigenous Languages. Papers presented at the Annual Stabilizing Indigenous Languages Symposium (5th, Louisville, KY, May 15-16, 1998).

    ERIC Educational Resources Information Center

    Reyhner, Jon, Ed.; Cantoni, Gina, Ed.; St. Clair, Robert N., Ed.; Yazzie, Evangeline Parsons, Ed.

    This volume of conference papers examines issues and approaches in the revitalization of American Indian and other indigenous languages. Sections discuss obstacles and opportunities for language revitalization, language revitalization efforts and approaches, the role of writing in language revitalization, and using technology in language…

  15. Local Air Quality Conditions and Forecasts

    MedlinePlus

    Local Air Quality Conditions Zip Code: State : My Current Location Map Center Forecast AQI Current AQI Current Ozone Current PM ... Ozone Loop PM Loop AQI: Good (0 - 50) Air quality is considered satisfactory, and air pollution poses little ...

  16. Loop-to-loop coupling.

    SciTech Connect

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

    2012-05-01

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

  17. A Review: Using Pyrolysis and its Bioproducts to Help Close the Loop in Sustainable Life Support Systems

    NASA Technical Reports Server (NTRS)

    McCoy, LaShelle E.

    2013-01-01

    The next step in human exploration of space is beyond low Earth orbit and possibly to sites such as the Moon and Mars. Resupply of critical life support components for missions such as these are difficult or impossible. Life support processes for closing the loop of water, oxygen and carbon have to be identified. Currently, there are many technologies proposed for terrestrial missions for waste, water, air processing. and the creation of consumables. There are a variety of different approaches, but few address all of these issues simultaneously. One candidate is pyrolysis; a method where waste streams can be heated in the absence of oxygen to undergo a thermochemical conversion producing a series of bioproducts. Bioproducts like biochar made from non-edible biomass and human solid waste can possibly provide valuable benefits such as waste reduction, regolith fertilization for increased food production, and become a consumable for water processing and air revitalization systems. Syngas containing hydrogen, carbon monoxide and carbon dioxide, can be converted to methane and dimethyl ether to create propellants. Bio-oils can be utilized as a heating fuel or fed to bioreactors that utilize oil-eating microbes.

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

    SciTech Connect

    Mohanty, Subhasish; Soppet, William; Majumdar, Saurin; Natesan, Ken

    2015-09-01

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

  19. Chemical Looping Combustion Kinetics

    SciTech Connect

    Edward Eyring; Gabor Konya

    2009-03-31

    One of the most promising methods of capturing CO{sub 2} emitted by coal-fired power plants for subsequent sequestration is chemical looping combustion (CLC). A powdered metal oxide such as NiO transfers oxygen directly to a fuel in a fuel reactor at high temperatures with no air present. Heat, water, and CO{sub 2} are released, and after H{sub 2}O condensation the CO{sub 2} (undiluted by N{sub 2}) is ready for sequestration, whereas the nickel metal is ready for reoxidation in the air reactor. In principle, these processes can be repeated endlessly with the original nickel metal/nickel oxide participating in a loop that admits fuel and rejects ash, heat, and water. Our project accumulated kinetic rate data at high temperatures and elevated pressures for the metal oxide reduction step and for the metal reoxidation step. These data will be used in computational modeling of CLC on the laboratory scale and presumably later on the plant scale. The oxygen carrier on which the research at Utah is focused is CuO/Cu{sub 2}O rather than nickel oxide because the copper system lends itself to use with solid fuels in an alternative to CLC called 'chemical looping with oxygen uncoupling' (CLOU).

  20. Atmosphere Revitalization Technology Development for Crewed Space Exploration

    NASA Technical Reports Server (NTRS)

    Perry, Jay L.; Carrasquillo, Robyn L.; Harris, Danny W.

    2006-01-01

    As space exploration objectives extend human presence beyond low Earth orbit, the solutions to technological challenges presented by supporting human life in the hostile space environment must build upon experience gained during past and present crewed space exploration programs. These programs and the cabin atmosphere revitalization process technologies and systems developed for them represent the National Aeronautics and Space Administration s (NASA) past and present operational knowledge base for maintaining a safe, comfortable environment for the crew. The contributions of these programs to the NASA s technological and operational working knowledge base as well as key strengths and weaknesses to be overcome are discussed. Areas for technological development to address challenges inherent with the Vision for Space Exploration (VSE) are presented and a plan for their development employing unit operations principles is summarized

  1. Workers' Housing Estates In Postindustrial Cities - Modernization Or Revitalization?

    NASA Astrophysics Data System (ADS)

    Gaweł, Dariusz

    2015-09-01

    The article presents a part of the results on the physiognomy of a postindustrial city under conditions of economic transformation in Poland. The study area encompasses industrial centers located in the region of the Central Industrial District (Centralny Okręg Przemysłowy - COP) in the Świętokrzystkie and Mazowieckie voivodeships (districts). The specific urban structure of the industrial city and unemployment among its inhabitants resulting from ownership transformations generate various problems. The workers' neighborhoods and colonies, which sprouted up so quickly at the beginning of the XX century, were a supply base for the rapidly developing industrial centers. Their clear urban structure and cultural potential they possess predispose them to developing necessary repair programs. Thus, the article draws attention to this form of settlement on the one hand, and on the other characterizes the activities assumed by gminas (municipalities) in the scope of modernizing and revitalizing these areas.

  2. The revitalization of the Public Health Service Commissioned Corps.

    PubMed Central

    Koop, C E; Ginzburg, H M

    1989-01-01

    The Public Health Service (PHS) is the second oldest uniformed service of the United States; its tradition commenced with the establishment of the Marine Hospital Service in 1798. Congress, in 1889, established the United States Public Health Service Commissioned Corps under the aegis of the Treasury. The Corps was created as a uniformed nonmilitary service with a distinct uniform, insignia, and with titles, pay, and retirement protocols that corresponded to those of the uniformed military services (the Armed Forces). Initially the health care system of the country, and Commissioned Corps members, were concerned with infectious and vitamin-deficiency diseases; more recently the nation's medical community has focused on cardiovascular diseases, cancer, and AIDS. A comprehensive revitalization of the Commissioned Corps began in April 1987. The intent was to restore the Commissioned Corps to its traditional leadership role as a cadre of mobile, compassionate experts ensuring the nation's health. The revitalization activities have been successful. The Commissioned Corps has approximately 5,500 active duty officers. The Surgeon General directed the development of career tracks for 11 categories of commissioned officers to increase the opportunities for professional development within the PHS and thus increase retention and professional growth. The theme for the 1989 celebration of the centennial of the Commissioned Corps is "a century of service with distinction." A hundred years from now, at the bicentennial of the Commissioned Corps, the current Surgeon General would like it to be said that the Public Health Service has had "two centuries of service with distinction." Images p106-a p107-a p107-b p108-a p109-a PMID:2495543

  3. Revitalizing primary health care--another utopian goal?

    PubMed

    Marahatta, Sujan B

    2010-01-01

    The quest for greater efficiency, fairness and responsiveness to the expectation of the people that system serve have brought about three generations of health system reforms in the twentieth century. The first generation saw the founding of national health care systems and extension to middle income nations of social insurance systems in the 1940s and 1950s. By the late 1960s the rising costs of hospital based care, its usage by better off, inaccessibility by the poor and rural population of even the most basic services heralded second generation reforms promoting primary health care as a means of achieving the affordable universal coverage. It included the best public health strategy that is prevention and the highest ethical principle of public health that is equity. It was expected the best system for reaching households with essential and affordable care, and the best route towards universal coverage. The primary health care approach though adopted universally did not materialize its notion of translating ethos of Health for All by 2000. Overall, primary health care movement by the end of 20th century became lifeless. Since the Declaration of Alma-Ata, fundamental changes have occurred affecting health service delivery, such as economic development and financing approaches, globalization of trade and knowledge, and the shift to privatization. This is the time to develop a new vision, taking into consideration the many changes affecting global health and the strategic developments in health of recent years. With this recognition, the third generation of reforms now underway in many countries is driven by the idea of responding more to demand, assuring access for the poor and emphasizing financing rather than just provision within the public sector. The key concern is: how to translate ethos of revitalizing in the reality. Otherwise the revitalizing concept will turn into utopian goal so like HFA by 2000 strategy.

  4. Partnership for the Revitalization of National Wind Tunnel Force Measurement Capability

    NASA Technical Reports Server (NTRS)

    Rhew, Ray D.; Skelley, Marcus L.; Woike, Mark R.; Bader, Jon B.; Marshall, Timothy J.

    2009-01-01

    Lack of funding and lack of focus on research over the past several years, coupled with force measurement capabilities being decentralized and distributed across the National Aeronautics and Space Administration (NASA) research centers, has resulted in a significant erosion of (1) capability and infrastructure to produce and calibrate force measurement systems; (2) NASA s working knowledge of those systems; and (3) the quantity of high-quality, full-capability force measurement systems available for use in aeronautics testing. Simultaneously, and at proportional rates, the capability of industry to design, manufacture, and calibrate these test instruments has been eroding primarily because of a lack of investment by the aeronautics community. Technical expertise in this technology area is a core competency in aeronautics testing; it is highly specialized and experience-based, and it represents a niche market for only a few small precision instrument shops in the United States. With this backdrop, NASA s Aeronautics Test Program (ATP) chartered a team to examine the issues and risks associated with the problem, focusing specifically on strain- gage balances. The team partnered with the U.S. Air Force s Arnold Engineering Development Center (AEDC) to exploit their combined capabilities and take a national level government view of the problem. This paper describes the team s approach, its findings, and its recommendations, and the current status for revitalizing the government s balance capability with respect to designing, fabricating, calibrating, and using the instruments.

  5. Michigan State U. Joins Forces with Blighted Benton Harbor in Effort to Revitalize City.

    ERIC Educational Resources Information Center

    McMillen, Liz

    1986-01-01

    Michigan State University's Center for Urban Affairs is contributing their expertise, research skills, and volunteer time to help Benton Harbor revitalize. Faculty members and students have already completed studies on street repairs, the homeless, and hotel development. (MLW)

  6. SMARTE: HELPING COMMUNITIES OVERCOME OBSTACLES TO REVITALIZATION (04/23/07)

    EPA Science Inventory

    Sustainable Management Approaches and Revitalization Tools - electronic (SMARTe), is an open-source, web-based, decision support system for developing and evaluating future reuse scenarios for potentially contaminated land. SMARTe contains information and analysis tools for all a...

  7. GET SMARTE: A DECISION SUPPORT SYSTEM TO REVITALIZE COMMUNITIES - CABERNET 2007

    EPA Science Inventory

    Sustainable Management Approaches and Revitalization Tools - electronic (SMARTe), is an open-source, web-based, decision support system for developing and evaluating future reuse scenarios for potentially contaminated land. SMARTe contains information and analysis tools for all a...

  8. Whitewright, Texas to Receive $200,000 from EPA to Revitalize Business District

    EPA Pesticide Factsheets

    DALLAS - (March 13, 2015) The U.S. Environmental Protection Agency (EPA) recently announced the selection of the City of Whitewright, Texas to receive $200,000 to plan redevelopment and revitalization for the city's business district. The city will

  9. Regeneration of the dentine-pulp complex with revitalization/revascularization therapy: challenges and hopes.

    PubMed

    Lin, L M; Ricucci, D; Huang, G T-J

    2014-08-01

    The concept of regenerative endodontics has gained much attention in clinical endodontics in the past decade. One aspect of this discipline is the application of revitalization/revascularization therapies for infected and/or necrotic immature pulps in permanent teeth. Following the publication of a case report (Iwaya et al. ), investigators have been rigorously examining the types of tissues formed in the canals as well as exploring strategies to regenerate the pulp-dentine complex in revitalized teeth. This review will provide an update on the types of tissues generated in the canals after revitalization/revascularization therapy in both animal and human studies. The understanding of the role of stem cells and microenvironment in the process of wound healing resulting in either regeneration or repair will be thoroughly discussed. Stem cells and microenvironmental cues introduced into the canal during revitalization/revascularization procedures will be examined. In addition, requirement of a sterile microenvironment in the canal and vital tissue generation in revitalization/revascularization therapy will be emphasized. The challenges that we face and the hopes that we have in revitalization/revascularization therapy for regenerative endodontics will be presented.

  10. Air Vehicle Technology Integration Program (AVTIP) Delivery Order 0015: Open Control Platform (OCP) Software Enabled Control (SEC) Hardware in the Loop Simulation - OCP Hardware Integration

    DTIC Science & Technology

    2005-06-01

    AFRL-VA-WP-TR-2006-3075 AIR VEHICLE TECHNOLOGY INTEGRATION PROGRAM (AVTIP) Delivery Order 0015: Open Control Platform (OCP) Software Enabled...2001– 05/28/2004 5a. CONTRACT NUMBER F33615-00-D-3052-0015 5b. GRANT NUMBER 4. TITLE AND SUBTITLE AIR VEHICLE TECHNOLOGY INTEGRATION PROGRAM

  11. Nighttime Lights, Socioeconomic Development, and Revitalization Policies in Northeast Asia

    NASA Astrophysics Data System (ADS)

    Bennett, M.; Smith, L. C.

    2015-12-01

    Nighttime lights are typically used as a proxy for population and economic growth, yet they can also reveal socioeconomic decline. We use two night light datasets to infer socioeconomic patterns and trends in the Russian Far East, Northeast China, and North Korea, a cross-border region impacted by the 1991 collapse of the USSR. First, using the annual stable light composites from the DMSP/OLS satellites, we find that generally, nighttime lights declined in the Russian Far East, increased in Northeast China, and fluctuated in North Korea between 1992 and 2012. By 2012, lighting in most of the Russian Far East had not recovered to 1992 levels. In Northeast China, a government revitalization program may have increased lighting during the mid-2000s, suggesting sensitivity of remotely sensed nighttime lights to regional development policies. Yet caveats with DMSP/OLS data include low spatial and radiometric resolutions, saturation, and blooming. The Day/Night Band (DNB) of the Suomi NPP satellite, however, launched in October 2011, has higher quality, enabling improved monitoring of socioeconomic trends in the region. For our second night lights dataset, we use both nightly images and monthly DNB composites to make inferences regarding socioeconomic activities at finer spatial and temporal resolutions from 2012-2015. Cross-border activity in particular emerges in finer detail, allowing us to examine specific transport corridors and sites of industrial and natural resource production that involve both Russian and Chinese partners.

  12. A renewed focus on primary health care: revitalize or reframe?

    PubMed Central

    2010-01-01

    The year 2008 celebrated 30 years of Primary Health Care (PHC) policy emerging from the Alma Ata Declaration with publication of two key reports, the World Health Report 2008 and the Report of the Commission on the Social Determinants of Health. Both reports reaffirmed the relevance of PHC in terms of its vision and values in today's world. However, important challenges in terms of defining PHC, equity and empowerment need to be addressed. This article takes the form of a commentary reviewing developments in the last 30 years and discusses the future of this policy. Three challenges are put forward for discussion (i) the challenge of moving away from a narrow technical bio-medical paradigm of health to a broader social determinants approach and the need to differentiate primary care from primary health care; (ii) The challenge of tackling the equity implications of the market oriented reforms and ensuring that the role of the State in the provision of welfare services is not further weakened; and (iii) the challenge of finding ways to develop local community commitments especially in terms of empowerment. These challenges need to be addressed if PHC is to remain relevant in today's context. The paper concludes that it is not sufficient to revitalize PHC of the Alma Ata Declaration but it must be reframed in light of the above discussion. PMID:20673329

  13. Ozone - Current Air Quality Index

    MedlinePlus

    Local Air Quality Conditions Zip Code: State : My Current Location Forecast Current AQI AQI Loop More Maps AQI: Good (0 - ... September 2016, Busan, South Korea. More more announcements Air Quality Basics Air Quality Index | Ozone | Particle Pollution | Smoke ...

  14. Water Stream "Loop-the-Loop"

    ERIC Educational Resources Information Center

    Jefimenko, Oleg

    1974-01-01

    Discusses the design of a modified loop-the-loop apparatus in which a water stream is used to illustrate centripetal forces and phenomena of high-velocity hydrodynamics. Included are some procedures of carrying out lecture demonstrations. (CC)

  15. 76 FR 1665 - Stakeholder Meetings Regarding the U.S.-Flag Great Lakes Fleet Revitalization Study; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-11

    ... Maritime Administration Stakeholder Meetings Regarding the U.S.-Flag Great Lakes Fleet Revitalization Study... public listening- session meetings it is conducting to gather data and comments to inform the Maritime Administration's U.S.-Flag Great Lakes Fleet Revitalization Study. MARAD inadvertently listed the incorrect...

  16. In the Name of Language: School-Based Language Revitalization, Strategic Solidarities, and State Power in the French Basque Country

    ERIC Educational Resources Information Center

    Heidemann, Kai A.

    2014-01-01

    This article explores the mobilization dynamics of a school-based minority language revitalization initiative in the French Basque Country, known as the Ikastola Movement. Bringing the study of language revitalization into dialogue with social movement theory, I discuss how the solidarity of Basque language activists was influenced by state-level…

  17. Strategies for Revitalizing Organizations: Regaining the Competitive Edge

    NASA Technical Reports Server (NTRS)

    Nysmith, C. Robert

    1987-01-01

    During the last decade, the United States has lost competitive stature in the world. Challenged daily by a technically sophisticated and vitalized global economy, industry and Government are examining quality and productivity initiatives with which to meet the foreign competitive challenge. At stake are our quality of life and our standard of living for the remainder of this century and beyond. Being competitive is an ongoing process, tuned to an awareness and understanding of the dynamics of the world marketplace and to the changing nature of the work environment. Solutions to America's quality and productivity problems do not exist independently within any organization or industry or at any given level of society. Success depends on commitment, partnership, meshing of goals and responsibilities, mutual respect and understanding, and a desire to be first. A change in organizational management culture is required. Traditional authoritarian management practices must give way to enlightened leadership initiatives that stress employee involvement and participation. There must be a lessening of adversarial relationships between management and labor and between industry and Government. Quality and productivity are understood to be the end result of an integrated process which begins with vigorous, committed leadership and ends with a satisfied customer. The essential elements in the revitalization process are organized in this report into seven strategies which represent the major findings of the Second NASA Symposium on Quality and Productivity. Each strategy is then broken down into its principal themes which are presented as recommendations. No one strategy can stand apart from any other; all are interrelated and work together.

  18. The revitalization of U.S. dental education.

    PubMed

    DePaola, Dominick P

    2008-02-01

    Revitalization of dental education in the United States is an imperative, but it depends mainly on the willingness of dental school faculty to make great changes. My remarks address a system of education of dental professionals in relation to other health professionals whose vision seems at times to have surpassed ours. I advocate for a revitalization of our profession in order to stand at the fore when it comes to ensuring the health and well-being of the public. Thanks to advances in molecular medicine, health care is being transformed from a system of treating disease to one that provides predictive, preemptive, and personalized care. This presentation makes recommendations for rethinking the current system of dental education in order to elevate dentistry to its rightful place as a vibrant health care leader. Dental education needs to be a source of new knowledge, discovery, and innovation to sustain its legacy as a learned profession. Graduates must be lifelong learners who can critically evaluate science and technology for the good of their patients. Future dentists should be providers of primary care, yet data suggest that the organizational structure to support this vision is lacking. The accreditation system, interrelated with licensure and National Boards, needs to set a better floor. While independence is an admirable goal, I see too much variation in the accreditation system. We must overcome fears and politics to upgrade the profession as pharmacy did when it introduced the Pharm.D. degree. With that came a change in the entire system of pharmacy education and clinical practice and recognition of pharmacists as members of an interdisciplinary health care team. Dentistry and dental education are doing a lot that is good, but we must and can do even better if the profession is to thrive as a respected member of the health professions delivering high-quality, evidence-based care to the public. Dental students, faculty, and practitioners must have command

  19. Revitalization of Energy Supply Systems in the Scale of a Town, a District and an Island

    NASA Astrophysics Data System (ADS)

    Juchimiuk, Justyna

    2016-09-01

    Model actions undertaken in HafenCity and Wilhelmsburg during IBA Hamburg 2006- 13 as well as energy transformation of Danish island of Samsø towards self-sufficiency are examples of the use of energy as one of the key factors in the design of revitalization process in various scales. An important issue is to determine the impact of renewable energy systems on design process, architecture and urbanism of revitalized structures. Article examines the programs and projects related to the processes: renewal of degraded inner-industrial areas (brownfields), ecological restoration of degraded land, the revitalization of port and underdeveloped areas in the aspects of climate protection, the use of energy from renewable sources and improvement of technical conditions of building substance while maintaining the principles of sustainable development.

  20. Your Language or Ours? Inclusion and Exclusion of Non-Indigenous Majorities in Maori and Sámi Language Revitalization Policy

    ERIC Educational Resources Information Center

    Albury, Nathan John

    2015-01-01

    Since the second half of the twentieth century, post-colonial governments have commonly sought to revitalize the indigenous languages their imperialist predecessors hoped to eradicate. Although the impetus to revitalize is shared, the question of excluding or including the non-indigenous majority in the revitalization process, and encouraging them…

  1. Language revitalization in Native North America--issues of intellectual property rights and intellectual sovereignty.

    PubMed

    Tatsch, Sheri

    2004-01-01

    Language revitalization, oral tradition and epistemology are expressions of Native peoples intellectual sovereignty, and thus the foundation for indigenous intellectual property rights. As the people of California move towards language and cultural revitalization the question arises: What constitutes or constructs the definitions of intellectual property and how can appropriation of indigenous knowledge be protected? Looking at the issues faced by the California's indigenous populace and by implication, other indigenous peoples in the United States, this essay examines how protection may be afforded under the United Nations definition of 'heritage'. Given that the holding safe of a 'culture' or 'heritage' is inclusive of language, and thus has been determined to be a human right.

  2. Performance of the 0.3-meter transonic cryogenic tunnel with air, nitrogen, and sulfur hexafluoride media under closed loop automatic control

    NASA Technical Reports Server (NTRS)

    Balakrishna, S.; Kilgore, W. Allen

    1995-01-01

    The NASA Langley 0.3-m Transonic Cryogenic Tunnel was modified in 1994, to operate with any one of the three test gas media viz., air, cryogenic nitrogen gas, or sulfur hexafluoride gas. This document provides the initial test results with respect to the tunnel performance and tunnel control, as a part of the commissioning activities on the microcomputer based controller. The tunnel can provide precise and stable control of temperature to less than or equal to +/- 0.3 K in the range 80-320 K in cyro mode or 300-320 K in air/SF6 mode, pressure to +/- 0.01 psia in the range 15-88 psia and Mach number to +/- O.0015 in the range 0.150 to transonic Mach numbers up to 1.000. A new heat exchanger has been included in the tunnel circuit and is performing adequately. The tunnel airfoil testing benefits considerably by precise control of tunnel states and helps in generating high quality aerodynamic test data from the 0.3-m TCT.

  3. Fast flux locked loop

    DOEpatents

    Ganther, Jr., Kenneth R.; Snapp, Lowell D.

    2002-09-10

    A flux locked loop for providing an electrical feedback signal, the flux locked loop employing radio-frequency components and technology to extend the flux modulation frequency and tracking loop bandwidth. The flux locked loop of the present invention has particularly useful application in read-out electronics for DC SQUID magnetic measurement systems, in which case the electrical signal output by the flux locked loop represents an unknown magnetic flux applied to the DC SQUID.

  4. The preprocessed doacross loop

    NASA Technical Reports Server (NTRS)

    Saltz, Joel H.; Mirchandaney, Ravi

    1990-01-01

    Dependencies between loop iterations cannot always be characterized during program compilation. Doacross loops typically make use of a-priori knowledge of inter-iteration dependencies to carry out required synchronizations. A type of doacross loop is proposed that allows the scheduling of iterations of a loop among processors without advance knowledge of inter-iteration dependencies. The method proposed for loop iterations requires that parallelizable preprocessing and postprocessing steps be carried out during program execution.

  5. OPE for super loops

    NASA Astrophysics Data System (ADS)

    Sever, Amit; Vieira, Pedro; Wang, Tianheng

    2011-11-01

    We extend the Operator Product Expansion for Null Polygon Wilson loops to the Mason-Skinner-Caron-Huot super loop dual to non MHV gluon amplitudes. We explain how the known tree level amplitudes can be promoted into an infinite amount of data at any loop order in the OPE picture. As an application, we re-derive all one loop NMHV six gluon amplitudes by promoting their tree level expressions. We also present some new all loops predictions for these amplitudes.

  6. Revitalizing Educational Counseling: How Career Theory Can Inform a Forgotten Practice

    ERIC Educational Resources Information Center

    Reardon, Robert C.; Bertoch, Sara C.

    2011-01-01

    Educational counseling has declined as a counseling specialization in the United States, although the need for this intervention persists and is being met by other providers. This article illustrates how career theories such as Holland's RIASEC theory can inform a revitalized educational counseling practice in secondary and postsecondary settings.…

  7. Not Just "Situaciones de la Vida": Professionalization and Indigenous Language Revitalization in the Andes

    ERIC Educational Resources Information Center

    Hornberger, Nancy H.; Swinehart, Karl F.

    2012-01-01

    Within discourses of language endangerment, life stages such as child language acquisition, adolescent language shift, and the death of community elders figure prominently, but what of the role of other, intermediate life stages during adulthood and professional life in the course of language obsolescence or revitalization? Drawing from long-term…

  8. SMARTe: An MCDA Approach To Revitalize Communities And Restore The Environment

    EPA Science Inventory

    SMARTe (Sustainable Management Approaches and Revitalization Tools - electronic) is a free, open-source, web-based, decision-support system that helps revitalization stakeholders (communities, developers, regulators, etc.) overcome obstac...

  9. Remediation to restoration to revitalization: A path forward for AOCs progress report

    EPA Science Inventory

    At the 2016 Great Lakes Areas of Concern (AOC) Conference, researchers from the USEPA Office of Research and Development (ORD) sparked conversation about community revitalization and the different states of progress throughout the basin. The conversation was meant to provide AOC ...

  10. TOOLS FOR OVERCOMING OBSTACLES TO REVITALIZATION: SMARTE AND START-UP

    EPA Science Inventory

    In 2001, the US-German Bilateral Working Group (BWG) identified more than 40 obstacles to site revitalization which occurred in both countries. From 2001-2005, the BWG developed tools and techniques for overcoming these obstacles. Five joint workshops were held on the following r...

  11. The Role and Impact of Continuing Education on Rural Revitalization: A Case Study

    ERIC Educational Resources Information Center

    Miller, Marilyn

    2008-01-01

    This article presents the findings of a study that explored the role and impact of continuing education on rural revitalization. A community development approach, academic expertise, and a university's resources were used to assist the citizens of Montmartre, Saskatchewan, to establish Centre 48, an arts and continuing education centre. Courses…

  12. More than Words: Towards a Development-Based Approach to Language Revitalization

    ERIC Educational Resources Information Center

    Henderson, Brent; Rohloff, Peter; Henderson, Robert

    2014-01-01

    Existing models for language revitalization focus almost exclusively on language learning and use. While recognizing the value of these models, we argue that their effective application is largely limited to situations in which languages have low numbers of speakers. For languages that are rapidly undergoing language shift, but which still…

  13. Speech Community-Based Documentation, Description, and Revitalization: Kari'nja in Konomerume

    ERIC Educational Resources Information Center

    Yamada, Racquel-Maria

    2010-01-01

    Since 2005, I have been working with members of the Kari'nja community of Konomerume, Suriname to document, describe, preserve, and revitalize their heritage language, the Aretyry dialect of Kari'nja (Cariban family). Simultaneously, I have worked to develop, pilot, and articulate a model of field research that depends on participation from speech…

  14. Documentation and Revitalization of the Zhuang Language and Culture of Southwestern China through Linguistic Fieldwork

    ERIC Educational Resources Information Center

    Bodomo, Adams

    2010-01-01

    This article outlines innovative strategies, methods, and techniques for the documentation and revitalization of "Zhuang" language and culture through linguistic fieldwork. Zhuang, a Tai-Kadai language spoken mainly in the rural areas of the Guangxi Zhuang Autonomous Region of southwestern China, is the largest minority language in…

  15. Revitalizing Politics Now and Then: Howard Zinn on Dissent, Democracy, and Education

    ERIC Educational Resources Information Center

    Cooley, Aaron

    2009-01-01

    This paper presents a discussion of Howard Zinn's intellectual and political ideas. Through the analysis of selections from his immense body of work, several interrelated themes emerge. Drawing more attention to these notions of dissent and democracy is crucial to revitalizing education at all levels and vital to advancing the public discourse…

  16. "We Can't Feel Our Language": Making Places in the City for Aboriginal Language Revitalization

    ERIC Educational Resources Information Center

    Baloy, Natalie J. K.

    2011-01-01

    This article explores possibilities for extending aboriginal language education opportunities into the urban domain based on qualitative research in Vancouver, British Columbia. The author argues that aboriginal language revitalization efforts have a place in the city, as demonstrated by emerging language ideologies of urban aboriginal people…

  17. SUSTAINABLE MANAGEMENT APPROACHES AND REVITALIZATION TOOLS - ELECTRONIC (SMARTE) - 09-05-2007

    EPA Science Inventory

    Revitalization of sites potentially contaminated with environmentally toxic or hazardous materials (e.g., brownfields) is a global concern requiring a multi-disciplinary approach to mitigate the risks to human health and the environment. Many countries have committed extensive re...

  18. Revitalization of the Shared Commons: Education for Sustainability and Marginalized Cultures

    ERIC Educational Resources Information Center

    Glasson, George E.

    2010-01-01

    Education for sustainability provides a vision for revitalizing the environmental commons while preserving cultural traditions and human rights. What happens if the environmental commons is shared by two politically disparate and conflicting cultures? As in many shared common lands, what happens if one culture is dominant and represents a more…

  19. Revitalizing Curriculum Leadership: Inspiring and Empowering Your School Community. Second Edition

    ERIC Educational Resources Information Center

    Brubaker, Dale L.

    2004-01-01

    When we learn, we learn through our own experiences. So when we teach, how do we incorporate our own invaluable life lessons into a state mandated curriculum? Dale Brubaker's "Revitalizing Curriculum Leadership" provides an innovative and liberating solution to this problem. In this updated resource, the author tells why educators need to move…

  20. EPA Brownfields Grant Will Aid City of St. Helens with Plans to Revitalize Waterfront Area

    EPA Pesticide Factsheets

    (Seattle - March 17, 2015) The City of St. Helens, Oregon has been selected to receive a $200,000 Brownfields Area-Wide Planning (AWP) grant from EPA to help move towards the goal of revitalizing a former industrial property along the Columbia River waterf

  1. EPA Brownfields Grant Will Aid City of Spokane with Plans to Revitalize Hillyard Industrial Area

    EPA Pesticide Factsheets

    (Seattle - March 17, 2015) The City of Spokane, Washington has been selected to receive a $200,000 Brownfields Area-Wide Planning (AWP) grant from EPA to help move towards the goal of revitalizing a former industrial property in their city.

  2. PHASE 3 CONFERENCE OF THE U.S.-GERMANY BILATERAL WORKING GROUP BROWNFIELDS REVITALIZATION

    EPA Science Inventory

    The US-Germany Bilateral Working Group began in 1990 between the USEPA and the German Federal Ministry for Education and Research. The Working Group held a series of workshops to identify ways to facilitate revitalization of potential Brownfield Sites. In 2005, two final Conferen...

  3. Evaluation of Blowdown and Condensation (B and C) Loop Behavior During Air Clearing Phase with a Prototypic Sparger Using the RELAP Code: CPT-3 Test

    SciTech Connect

    Jeung, J.S.; Ko, H.J.; Park, C.K.; Cho, S.; Song, C.H.

    2002-07-01

    KAERI has performed a series of blowdown tests to evaluate the performance of the prototypic sparger which will be used in the APR1400. Among the tests, the CPT-3 test is one of the fundamental blowdown tests and the objective of CPT-3 test was to determine the effect of air mass inside the piping on the IRWST boundary during an operation of SDVS (Safety Depressurization and Vent System). The test is conducted from the initial system pressure of 15.2 MPa and steam temperature of 343.2 deg. C. In the paper, the transient thermal-hydraulic behavior in the discharge line observed in the CPT-3 test is evaluated using the RELAP5/MOD3.1 code. The result shows that RELAP5/MOD3.1 can predict the blowdown behavior of the test facility properly and the code can be used as an evaluation tool for the verification of SDVS design of the APR 1400. (authors)

  4. Potential Cost Savings with 3D Printing Combined With 3D Imaging and CPLM for Fleet Maintenance and Revitalization

    DTIC Science & Technology

    2014-05-01

    1 Potential Cost Savings with 3D Printing Combined With 3D Imaging and CPLM for Fleet Maintenance and Revitalization David N. Ford...2014 4. TITLE AND SUBTITLE Potential Cost Savings with 3D Printing Combined With 3D Imaging and CPLM for Fleet Maintenance and Revitalization 5a...Manufacturing ( 3D printing ) 2 Research Context Problem: Learning curve savings forecasted in SHIPMAIN maintenance initiative have not materialized

  5. The North Carolina Department of Environment and Natural Resources: clean land, water, and air for healthy people and communities.

    PubMed

    Riegel, Lisa Diaz; Wakild, Charles; Boothe, Laura; Hildebrandt, Heather J; Nicholson, Bruce

    2012-01-01

    The North Carolina Department of Environment and Natural Resources works with communities and other agencies to sustain clean air, water, and land. Sustainability efforts include protecting air quality through community design, community enhancement through brownfields revitalization, community development strategies to protect water resources, and the integration of natural resource conservation.

  6. Pseudonoise code tracking loop

    NASA Technical Reports Server (NTRS)

    Laflame, D. T. (Inventor)

    1980-01-01

    A delay-locked loop is presented for tracking a pseudonoise (PN) reference code in an incoming communication signal. The loop is less sensitive to gain imbalances, which can otherwise introduce timing errors in the PN reference code formed by the loop.

  7. The Development of Models for Carbon Dioxide Reduction Technologies for Spacecraft Air Revitalization

    NASA Technical Reports Server (NTRS)

    Swickrath, Michael J.; Anderson, Molly

    2012-01-01

    Through the respiration process, humans consume oxygen (O2) while producing carbon dioxide (CO2) and water (H2O) as byproducts. For long term space exploration, CO2 concentration in the atmosphere must be managed to prevent hypercapnia. Moreover, CO2 can be used as a source of oxygen through chemical reduction serving to minimize the amount of oxygen required at launch. Reduction can be achieved through a number of techniques. NASA is currently exploring the Sabatier reaction, the Bosch reaction, and co- electrolysis of CO2 and H2O for this process. Proof-of-concept experiments and prototype units for all three processes have proven capable of returning useful commodities for space exploration. All three techniques have demonstrated the capacity to reduce CO2 in the laboratory, yet there is interest in understanding how all three techniques would perform at a system level within a spacecraft. Consequently, there is an impetus to develop predictive models for these processes that can be readily rescaled and integrated into larger system models. Such analysis tools provide the ability to evaluate each technique on a comparable basis with respect to processing rates. This manuscript describes the current models for the carbon dioxide reduction processes under parallel developmental efforts. Comparison to experimental data is provided were available for verification purposes.

  8. Round table part 2 : Identification of the key technologies and collaboration for air revitalization

    NASA Astrophysics Data System (ADS)

    Lasseur, Christophe; Tikhomirov, Alexander A.; Wheeler, Raymond

    2016-07-01

    The first metabolic needs in terms of urgency is of course oxygen and in terms of contaminants CO2. Over the years, many studies have been performed to recover oxygen from Co2 our from water. Within this part 2 of the roundtable it is proposed to perform a state te of the art of the main activities in the world and to identify overlap and synergies. Recommendation for potential collaboration or exchanges will be discussed.

  9. Finding of No Significant Impact: Military Family Housing Revitalization Project Nellis Air Force Base, Nevada

    DTIC Science & Technology

    2005-02-01

    units to be demolished in the Manch Manor area were constructed between 1960 and 1975 . The Manch Manor housing area is approximately 182 acres in...venomous snakes, lice , mites, and chiggers); structural pests (e.g., termites and powder post beetles); general household/nuisance pests (e.g., ants...Building Officials, 1997). Potential earthquakes in this zone have been correlated to a Modified Mercalli intensity (MMI) level value of VII

  10. Effects of Humidity Swings on Adsorption Columns for Air Revitalization: Modeling and Experiments

    NASA Technical Reports Server (NTRS)

    LeVan, M. Douglas; Finn, John E.

    1997-01-01

    The goal of this research was to develop a dynamic model which can predict the effect of humidity swings on activated carbon adsorption beds used to remove trace contaminants from the atmosphere in spacecraft. Specifically, the model was to be incorporated into a computer simulation to predict contaminant concentrations exiting the bed as a function of time after a humidity swing occurs. Predicted breakthrough curves were to be compared to experimentally measured results. In all respects the research was successful. The two major aspects of this research were the mathematical model and the experiments. Experiments were conducted by Mr. Appel using a fixed-bed apparatus at NASA-Ames Research Center during the summers of 1994 and 1995 and during the first 8 months of 1996. Mr. Appel conducted most of his mathematical modeling work at the University of Virginia. The simulation code was used to predict breakthrough curves using adsorption equilibrium correlations developed previously by M. D. LeVan's research group at the University of Virginia. These predictions were compared with the experimental measurements, and this led to improvements in both the simulation code and the apparatus.

  11. The Development of Models for Carbon Dioxide Reduction Technologies for Spacecraft Air Revitalization

    NASA Technical Reports Server (NTRS)

    Swickrath, Michael J.; Anderson, Molly

    2011-01-01

    Through the respiration process, humans consume oxygen (O2) while producing carbon dioxide (CO2) and water (H2O) as byproducts. For long term space exploration, CO2 concentration in the atmosphere must be managed to prevent hypercapnia. Moreover, CO2 can be used as a source of oxygen through chemical reduction serving to minimize the amount of oxygen required at launch. Reduction can be achieved through a number of techniques. The National Aeronautics and Space Administration (NASA) is currently exploring the Sabatier reaction, the Bosch reaction, and co-electrolysis of CO2 and H2O for this process. Proof-of-concept experiments and prototype units for all three processes have proven capable of returning useful commodities for space exploration. While all three techniques have demonstrated the capacity to reduce CO2 in the laboratory, there is interest in understanding how all three techniques would perform at a system-level within a spacecraft. Consequently, there is an impetus to develop predictive models for these processes that can be readily re-scaled and integrated into larger system models. Such analysis tools provide the ability to evaluate each technique on a comparable basis with respect to processing rates. This manuscript describes the current models for the carbon dioxide reduction processes under parallel developmental e orts. Comparison to experimental data is provided were available for veri cation purposes.

  12. Environmental Assessment: Military Family Housing Revitalization Travis Air Force Base, California

    DTIC Science & Technology

    2007-05-01

    of creating an attractive appearance No significant impacts are anticipated. Potential aesthetic impacts would be similar to those described...to control termites . Chlordane is a persistent bioaccumulative and toxic chemical; therefore, it may still be present in the soils within the MFH...expressed first in units in which they were promulgated. Equivalent units given in parentheses are based on a reference temperature of 25 degrees Celsius

  13. Exploring and revitalizing Indigenous food networks in Saskatchewan, Canada, as a way to improve food security.

    PubMed

    Gendron, Fidji; Hancherow, Anna; Norton, Ashley

    2016-03-22

    The project discussed in this paper was designed to expand research and instigate revitalization of Indigenous food networks in Saskatchewan, Canada, by exploring the current state of local Indigenous food networks, creating a Facebook page, organizing volunteer opportunities and surveying workshop participants regarding their knowledge and interest in Indigenous foods. The survey included Likert scale questions and qualitative questions. Project activities and survey results are discussed using statistical and qualitative analysis of the themes. Results indicate that participants are very interested in learning more about, and having greater access to, traditional foods and suggest that supporting Indigenous food networks may be an appropriate response to food insecurity in communities. Elders and community members are vital players in Indigenous foods exploration and revitalization in Saskatchewan by passing on traditional education.

  14. Farm crisis and rural revitalization in south-central New York during the early twentieth century.

    PubMed

    Osterud, Grey

    2010-01-01

    In contrast to both the critique of rural backwardness made by the Country Life Movement and the lament about rural declension expressed by proponents of agrarianism, the history of the Nanticoke Valley of south-central New York State demonstrates the possibilities for rural revitalization that lay in connections between the countryside and the city. In the early twentieth century, as long-settled families departed for urban employment, European immigrant families escaping the mines and mills bought abandoned farms. Motorized transport enabled farming families to send household members to the city each day and furnished them with a local market for their produce. This flexible combination of subsistence production, wage labor, and petty commodity production revitalized the rural economy and sustained the community in spite of the consolidation of the dairy industry. This essay explores the social changes that accompanied this profound reorientation of local life.

  15. Design, Development, Test, and Evaluation of Atmosphere Revitalization and Environmental Monitoring Systems for Long Duration Missions

    NASA Technical Reports Server (NTRS)

    Roman, Monsi C.; Perry, Jay L.; Jan, Darrell L.

    2012-01-01

    The Advanced Exploration Systems Program's Atmosphere Resource Recovery and Environmental Monitoring (ARREM) project is working to mature optimum atmosphere revitalization and environmental monitoring system architectures. It is the project's objective to enable exploration beyond Lower Earth Orbit (LEO) and improve affordability by focusing on three primary goals: 1) achieving high reliability, 2) reducing dependence on a ground-based logistics resupply model, and 3) maximizing commonality between atmosphere revitalization subsystem components and those needed to support other exploration elements. The ARREM project's strengths include using existing developmental hardware and testing facilities, when possible, and and a well-coordinated effort among the NASA field centers that contributed to past ARS and EMS technology development projects.

  16. Specifics of Formal and Legal Issues in Processes of Revitalizing Post-Industrial Buildings

    NASA Astrophysics Data System (ADS)

    Kochański, Paweł

    2016-12-01

    The article deals with issues from the initial phase of the investment process connected with revitalizing postindustrial buildings: planning and programming investments in the functional and financial scope, as well as designing. The described formal and legal aspects are the result of a study of a few projects concerning the adaptation of buildings to serving a new function in Zielona Góra and Żaganie. The conclusions drawn from an individual view into each of the described problems are no different than when designing new buildings. It is not until we look into the whole preparation and design process, and gathering all experiences from the formal-legal sphere, that allows us to notice that, in the case of revitalizing postindustrial buildings and their adaptation to serve modern-day functions, a multifaceted but also specific approach is required.

  17. Open-loop heat-recovery dryer

    SciTech Connect

    TeGrotenhuis, Ward Evan

    2013-11-05

    A drying apparatus is disclosed that includes a drum and an open-loop airflow pathway originating at an ambient air inlet, passing through the drum, and terminating at an exhaust outlet. A passive heat exchanger is included for passively transferring heat from air flowing from the drum toward the exhaust outlet to air flowing from the ambient air inlet toward the drum. A heat pump is also included for actively transferring heat from air flowing from the passive heat exchanger toward the exhaust outlet to air flowing from the passive heat exchanger toward the drum. A heating element is also included for further heating air flowing from the heat pump toward the drum.

  18. Designing sustainable and economically attractive brownfield revitalization options using an integrated assessment model.

    PubMed

    Schädler, S; Morio, M; Bartke, S; Rohr-Zänker, R; Finkel, M

    2011-03-01

    We describe the development of an integrated assessment model which evaluates redevelopment options of large contaminated brownfields and we present the application of the model in a case study. Aiming to support efficient and sustainable revitalization and communication between stakeholders, the presented assessment model integrates three pinnacles of brownfield revitalization: (i) subsurface remediation and site preparation costs, (ii) market-oriented economic appraisal, and (iii) the expected contribution of planned future land use to sustainable community and regional development. For the assessment, focus is set on the early stage of the brownfield redevelopment process, which is characterized by limited data availability and by flexibility in land use planning and development scope. At this stage, revealing the consequences of adjustments and alterations in planning options can foster efficiency in communication between the involved parties and thereby facilitates the brownfield revitalization process. Results from the case-study application indicate that the integrated assessment provides help in the identification of land use options beneficial in both a sustainable and an economical sense. For the study site it is shown on one hand that brownfield redevelopment is not automatically in line with sustainable regional development, and on the other hand it is demonstrated that additional contributions to sustainability are not intrinsically tied to increased costs.

  19. District steam and the St. Louis steam loop

    SciTech Connect

    Tierney, T.M.; Sauer, H.J. Jr.

    1999-07-01

    Owned and operated by large public electric utilities, district steam systems flourished in most northern US cities in the first half of this century. Following World War II, however, district steam systems became minor and, in some cases, unprofitable portions of the utilities' operations. Consequently, public utilities ceased promoting district steam to existing and potential customers, leading to the decline of their use. In recent years, district steam systems have been revitalized by independent enterprises that have the commitment and expertise to make these systems once again reliable and cost-effective energy sources. This paper reports on one such system, The St. Louis Steam Loop. The St. Louis steam loop consists of 22 miles of insulated underground steam piping encompassing a 400-square block area in the city's downtown business district. The loop is supplied with steam by the Ashley Plant, which was built in 1904 for the St. Louis World's Fair. Due to the rising cost of oil, which has been used to fuel the Ashley Plant since 1972, and the subsequent loss of customers, many people considered the steam system a dinosaur in the jet age. In 1982, Trigen-St. Louis Energy Corporation purchased the steam system and embarked on an aggressive campaign to upgrade all aspects of the system, including valves, piping, and meters. In 1999, Trigen-St. Louis will install an ISMW state-of-the-art combustion turbine cogenerator to provide 95% of the steam to the steam loop. A primary reason for the St. Louis Steam Loop's longevity is that it has reliably supplied steam to many downtown buildings for the better part of the 20th century.

  20. Functional Performance of an Enabling Atmosphere Revitalization Subsystem Architecture for Deep Space Exploration Missions

    NASA Technical Reports Server (NTRS)

    Perry, Jay L.; Abney, Morgan B.; Frederick, Kenneth R.; Greenwood, Zachary W.; Kayatin, Matthew J.; Newton, Robert L.; Parrish, Keith J.; Roman, Monsi C.; Takada, Kevin C.; Miller, Lee A.; Scott, Joseph P.; Stanley, Christine M.

    2013-01-01

    A subsystem architecture derived from the International Space Station's (ISS) Atmosphere Revitalization Subsystem (ARS) has been functionally demonstrated. This ISS-derived architecture features re-arranged unit operations for trace contaminant control and carbon dioxide removal functions, a methane purification component as a precursor to enhance resource recovery over ISS capability, operational modifications to a water electrolysis-based oxygen generation assembly, and an alternative major atmospheric constituent monitoring concept. Results from this functional demonstration are summarized and compared to the performance observed during ground-based testing conducted on an ISS-like subsystem architecture. Considerations for further subsystem architecture and process technology development are discussed.

  1. Multiprotein DNA Looping

    NASA Astrophysics Data System (ADS)

    Vilar, Jose M. G.; Saiz, Leonor

    2006-06-01

    DNA looping plays a fundamental role in a wide variety of biological processes, providing the backbone for long range interactions on DNA. Here we develop the first model for DNA looping by an arbitrarily large number of proteins and solve it analytically in the case of identical binding. We uncover a switchlike transition between looped and unlooped phases and identify the key parameters that control this transition. Our results establish the basis for the quantitative understanding of fundamental cellular processes like DNA recombination, gene silencing, and telomere maintenance.

  2. Introduction to Loop Heat Pipes

    NASA Technical Reports Server (NTRS)

    Ku, Jentung

    2015-01-01

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

  3. Revitalization of open apex teeth with apical periodontitis using a collagen-hydroxyapatite scaffold.

    PubMed

    Nevins, Alan J; Cymerman, Jerome J

    2015-06-01

    An enhanced revision of the revitalization endodontic technique for immature teeth with apical periodontitis has been described. It includes the addition of collagen-hydroxyapatite scaffold to the currently practiced revascularization technique. Four cases treated in series are presented in this report, 1 case involving 2 teeth. Periapical diagnoses of immature teeth included "asymptomatic apical periodontitis," "symptomatic apical periodontitis," and "acute apical abscess." Additionally, 1 fully developed tooth that had undergone root canal treatment that failed had a periapical diagnosis of acute apical abscess. An established revascularization protocol was used for all teeth. In addition to stimulating blood clots, all teeth were filled with collagen-hydroxyapatite scaffolds. Periapical radiolucencies healed in all teeth, and diffuse radiopacity developed within the coronal portions of canal spaces. Root development with root lengthening occurred in the immature nonvital maxillary premolar that had not undergone prior treatment. The technique of adding a collagen-hydroxyapatite scaffold to the existing revitalization protocol has been described in which substantial hard tissue repair has occurred. This may leave teeth more fully developed and less likely to fracture.

  4. Revitalization of the shared commons: education for sustainability and marginalized cultures

    NASA Astrophysics Data System (ADS)

    Glasson, George E.

    2010-06-01

    Education for sustainability provides a vision for revitalizing the environmental commons while preserving cultural traditions and human rights. What happens if the environmental commons is shared by two politically disparate and conflicting cultures? As in many shared common lands, what happens if one culture is dominant and represents a more affluent society with more resources and educational opportunities? In the case of the Tal and Alkaher study (Cult Stud Sci Edu, 2009), asymmetric power differences between the dominant Israeli society and the minority Arab population yielded different environmental narratives and perceptions of students involved in learning about a mediated conflict in national park land. Similarly, marginalized indigenous cultures in Malawi, Africa share common lands with the dominant European landowners but have distinctly different environmental narratives. Although indigenous ways of living with nature contribute to the sustainability of the environment and culture, African funds of knowledge are conspicuously absent from the Eurocentric school science curriculum. In contrast, examples of experiential learning and recent curriculum development efforts in sustainability science in Malawi are inclusive of indigenous knowledge and practices and are essential for revitalizing the shared commons.

  5. Community Revitalization by Geotourism: Tourism Study with Geoscience in Wakayama, Japan

    NASA Astrophysics Data System (ADS)

    Nakakushi, T.; Hisatomi, K.; Konomatsu, M.; Furukubo, A.

    2012-12-01

    This paper presents our community-revitalization project in Wakayama Prefecture, Japan. Wakayama Prefecture is the southwestern part of the Kii Peninsula. The Kii Peninsula, especially its southern part, has many geoscientifically important natural heritages such as the volcano-plutonic complex including well exposed ring dyke in the Kumano region. Those geoheritages have been considered just as on-site educational tools, and not received enough attentions as contents for geotours. UNESCO defines that a Geopark is a geographical area where geological heritage sites are part of a holistic concept of protection, education and sustainable development. UNESCO also describes that it is necessary to also include and highlight sites of ecological, archaeological, historical and cultural value within each Geopark. In many societies, natural, cultural and social history are inextricably linked and cannot be separated. We plan to have the region registered as a geopark by Japan (or Global) Geopark Network. In the context of community-revitalization, a "regional brand" has drawn attention for its potential to attract tourists. A Geopark may contribute to establish a regional brand.

  6. Explaining Warm Coronal Loops

    NASA Technical Reports Server (NTRS)

    Klimchuk, James A.; Karpen, Judy T.; Patsourakos, Spiros

    2008-01-01

    One of the great mysteries of coronal physics that has come to light in the last few years is the discovery that warn (- 1 INK) coronal loops are much denser than expected for quasi-static equilibrium. Both the excess densities and relatively long lifetimes of the loops can be explained with bundles of unresolved strands that are heated impulsively to very high temperatures. Since neighboring strands are at different stages of cooling, the composite loop bundle is multi-thermal, with the distribution of temperatures depending on the details of the "nanoflare storm." Emission hotter than 2 MK is predicted, but it is not clear that such emission is always observed. We consider two possible explanations for the existence of over-dense warm loops without corresponding hot emission: (1) loops are bundles of nanoflare heated strands, but a significant fraction of the nanoflare energy takes the form of a nonthermal electron beam rather then direct plasma heating; (2) loops are bundles of strands that undergo thermal nonequilibrium that results when steady heating is sufficiently concentrated near the footpoints. We present numerical hydro simulations of both of these possibilities and explore the observational consequences, including the production of hard X-ray emission and absorption by cool material in the corona.

  7. USE OF INTEGRATED PLANNING TOOLS FOR REVITALIZATION: SMARTE (U.S.) AND START-UP PLAN (GERMANY)

    EPA Science Inventory

    In 2001, the US-German Bilateral Working Group (BWG) identified more than 40 obstacles to site revitalization which occurred in both countries. From 2001-2005, the BWG developed tools and techniques for overcoming these obstacles. Five joint workshops were held on the following r...

  8. Urban, Suburban, and Rural Contexts of School Districts and Neighborhood Revitalization Strategies: Rediscovering Equity in Education Policy and Urban Planning

    ERIC Educational Resources Information Center

    Silverman, Robert Mark

    2014-01-01

    This article revisits the debate about school reform and homeownership-based strategies for neighborhood revitalization. It is based on an analysis of school districts in New York State using data from the American Community Survey (ACS) and the New York State Education Department (NYSED). Findings indicate that the relationship between schools…

  9. Language Revitalization and the Normalization of Basque: A Study of Teacher Perceptions and Expectations in the Basque Country

    ERIC Educational Resources Information Center

    Valadez, Concepción; Etxeberria, Feli; Intxausti, Nahia

    2015-01-01

    In the Basque Country, Northern Spain, Basque (Euskera) and Spanish are official languages. In recent decades, Basque language revitalization and the efforts to make this an unmarked language (normalization) have co-existed with the rapid increase in immigration from outside the Basque region, and most recently from outside Spain. Given the…

  10. Re-Branding Urban Schools: Urban Revitalization, Social Status, and Marketing Public Schools to the Upper Middle Class

    ERIC Educational Resources Information Center

    Cucchiara, Maia

    2008-01-01

    This article examines an effort to use urban schools to promote the revitalization of a large northeastern city in the United States. In order to attract and retain professional families to a regenerated central city, downtown schools are re-branded and promoted to such families as suitable for their children. The article draws on interviews and…

  11. SUSTAINABLE MANAGEMENT APPROACHES AND REVITALIZATION TOOLS-ELECTRONIC (SMARTE): OVERVIEW AND DEMONSTRATION FOR FINAL PHASE 3 CONFERENCE

    EPA Science Inventory

    The U.S. contingent of the U.S.-German Bilateral Working Group is developing Sustainable Management Approaches and Revitalization Tools-electronic (SMARTe). SMARTe is a web-based, decision support system designed to assist stakeholders in developing and evaluating alternative reu...

  12. Smart feedback loops

    NASA Astrophysics Data System (ADS)

    Chepurnov, A. S.; Gribov, I. V.; Gudkov, K. A.; Shumakov, A. V.; Shvedunov, V. I.

    1994-12-01

    It is necessary to find the golden mean in allocating the processing resources of a computer control system. Traditionally, feedback loops operate at the lower levels to ensure safe and stable operation of the accelerator. At present we use analogue and digital feedback loops. Some systems, such as the RF, require more complex algorithms. A possible way of providing these, using digital signal processors is described. The results of tests with the Race-Track Microtron Linac are given and the sources of the main internal and external disturbances have been analysed.

  13. Concentric Loop Surface Coil

    NASA Astrophysics Data System (ADS)

    Hernández-Flores, R.; Rodríguez-González, A. O.; Salgado-Lujambio, P.; Barrios-Alvarez, F. A.

    2002-08-01

    A surface coil for MRI consisted of two concentric loops was developed for brain imaging. Prior to build the coil prototype, the magnetic field (B1) generated by the coil was numerically simulated. This field simulation is based on the Biot-Savart law for the circular- and square-shaped loops. From these theoretical results, we can appreciate an improvement on the B1 homogeneity. Brain images obtained at 1.5 Tesla show a good sensitivity in a particular region of interest. Also, these images compared well against images obtained with a circular-shaped coil. This receiver coil can generate high quality brain images.

  14. Wilson-loop instantons

    NASA Technical Reports Server (NTRS)

    Lee, Kimyeong; Holman, Richard; Kolb, Edward W.

    1987-01-01

    Wilson-loop symmetry breaking is considered on a space-time of the form M4 x K, where M4 is a four-dimensional space-time and K is an internal space with nontrivial and finite fundamental group. It is shown in a simple model that the different vacua obtained by breaking a non-Abelian gauge group by Wilson loops are separated in the space of gauge potentials by a finite energy barrier. An interpolating gauge configuration is then constructed between these vacua and shown to have minimum energy. Finally some implications of this construction are discussed.

  15. Voice loops as coordination aids in space shuttle mission control.

    PubMed

    Patterson, E S; Watts-Perotti, J; Woods, D D

    1999-01-01

    Voice loops, an auditory groupware technology, are essential coordination support tools for experienced practitioners in domains such as air traffic management, aircraft carrier operations and space shuttle mission control. They support synchronous communication on multiple channels among groups of people who are spatially distributed. In this paper, we suggest reasons for why the voice loop system is a successful medium for supporting coordination in space shuttle mission control based on over 130 hours of direct observation. Voice loops allow practitioners to listen in on relevant communications without disrupting their own activities or the activities of others. In addition, the voice loop system is structured around the mission control organization, and therefore directly supports the demands of the domain. By understanding how voice loops meet the particular demands of the mission control environment, insight can be gained for the design of groupware tools to support cooperative activity in other event-driven domains.

  16. Voice loops as coordination aids in space shuttle mission control

    NASA Technical Reports Server (NTRS)

    Patterson, E. S.; Watts-Perotti, J.; Woods, D. D.

    1999-01-01

    Voice loops, an auditory groupware technology, are essential coordination support tools for experienced practitioners in domains such as air traffic management, aircraft carrier operations and space shuttle mission control. They support synchronous communication on multiple channels among groups of people who are spatially distributed. In this paper, we suggest reasons for why the voice loop system is a successful medium for supporting coordination in space shuttle mission control based on over 130 hours of direct observation. Voice loops allow practitioners to listen in on relevant communications without disrupting their own activities or the activities of others. In addition, the voice loop system is structured around the mission control organization, and therefore directly supports the demands of the domain. By understanding how voice loops meet the particular demands of the mission control environment, insight can be gained for the design of groupware tools to support cooperative activity in other event-driven domains.

  17. Independent Orbiter Assessment (IOA): Assessment of the atmospheric revitalization pressure control subsystem FMEA/CIL

    NASA Technical Reports Server (NTRS)

    Saiidi, M. J.

    1988-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the atmospheric Revitalization Pressure Control Subsystem (ARPCS) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the NASA FMEA/CIL proposed Post 51-L updates based upon the CCB/PRCB presentations and an informal criticality summary listing. A discussion of each discrepancy from the comparison is provided through additional analysis as required. These discrepancies were flagged as issues, and recommendations were made based on the FMEA data available at the time. This report documents the results of that comparison for the Orbiter ARPCS hardware.

  18. Evaluation of an Atmosphere Revitalization Subsystem for Deep Space Exploration Missions

    NASA Technical Reports Server (NTRS)

    Perry, Jay L.; Abney, Morgan B.; Conrad, Ruth E.; Frederick, Kenneth R.; Greenwood, Zachary W.; Kayatin, Matthew J.; Knox, James C.; Newton, Robert L.; Parrish, Keith J.; Takada, Kevin C.; Miller, Lee A.; Scott, Joseph P.; Stanley, Christine M.

    2015-01-01

    An Atmosphere Revitalization Subsystem (ARS) suitable for deployment aboard deep space exploration mission vehicles has been developed and functionally demonstrated. This modified ARS process design architecture was derived from the International Space Station's (ISS) basic ARS. Primary functions considered in the architecture include trace contaminant control, carbon dioxide removal, carbon dioxide reduction, and oxygen generation. Candidate environmental monitoring instruments were also evaluated. The process architecture rearranges unit operations and employs equipment operational changes to reduce mass, simplify, and improve the functional performance for trace contaminant control, carbon dioxide removal, and oxygen generation. Results from integrated functional demonstration are summarized and compared to the performance observed during previous testing conducted on an ISS-like subsystem architecture and a similarly evolved process architecture. Considerations for further subsystem architecture and process technology development are discussed.

  19. Cash management and revitalization of public medical centres in Nigeria: a strategic analysis.

    PubMed

    Agundu, Prince U C; Okon, Godwin B; Robinson, Eric T

    2007-01-01

    In times like this, when Nigeria (like many other developing countries) is bracing up to the contemporary challenges posed by adoption and advancement of globally driven millennium development goals (MDGs), public medical centers (PMCs) cannot afford to be reckoned with financial epilepsy, bankruptcy, and degeneracy. This concern informed the thrust of the study. In the process, pertinent research questions were posed which elicited corresponding hypothetical propositions. With primary data volunteered by 150 administrative officials drawn from PMCs across the country, analytical proceedings were facilitated by the application of chi-square (x2) technique. The findings brought to the fore, the general bad shape of cash management in PMCs in the country. The recommendations for urgent attention underscored the constitution of strategic budget communities (SBCs), revitalization of internal audit committees (IACs), and attraction of goodwill private-sector endowments through convincing justification of the utilization and optimization of current government logistic subventions.

  20. Revitalizing sociology: urban life and mental illness between history and the present.

    PubMed

    Fitzgerald, Des; Rose, Nikolas; Singh, Ilina

    2016-03-01

    This paper proposes a re-thinking of the relationship between sociology and the biological sciences. Tracing lines of connection between the history of sociology and the contemporary landscape of biology, the paper argues for a reconfiguration of this relationship beyond popular rhetorics of 'biologization' or 'medicalization'. At the heart of the paper is a claim that, today, there are some potent new frames for re-imagining the traffic between sociological and biological research - even for 'revitalizing' the sociological enterprise as such. The paper threads this argument through one empirical case: the relationship between urban life and mental illness. In its first section, it shows how this relationship enlivened both early psychiatric epidemiology, and some forms of the new discipline of sociology; it then traces the historical division of these sciences, as the sociological investment in psychiatric questions waned, and 'the social' become marginalized within an increasingly 'biological' psychiatry. In its third section, however, the paper shows how this relationship has lately been revivified, but now by a nuanced epigenetic and neurobiological attention to the links between mental health and urban life. What role can sociology play here? In its final section, the paper shows how this older sociology, with its lively interest in the psychiatric and neurobiological vicissitudes of urban social life, can be our guide in helping to identify intersections between sociological and biological attention. With a new century now underway, the paper concludes by suggesting that the relationship between urban life and mental illness may prove a core testing-ground for a 'revitalized' sociology.

  1. A model of the mechanisms of language extinction and revitalization strategies to save endangered languages.

    PubMed

    Fernando, Chrisantha; Valijärvi, Riitta-Liisa; Goldstein, Richard A

    2010-02-01

    Why and how have languages died out? We have devised a mathematical model to help us understand how languages go extinct. We use the model to ask whether language extinction can be prevented in the future and why it may have occurred in the past. A growing number of mathematical models of language dynamics have been developed to study the conditions for language coexistence and death, yet their phenomenological approach compromises their ability to influence language revitalization policy. In contrast, here we model the mechanisms underlying language competition and look at how these mechanisms are influenced by specific language revitalization interventions, namely, private interventions to raise the status of the language and thus promote language learning at home, public interventions to increase the use of the minority language, and explicit teaching of the minority language in schools. Our model reveals that it is possible to preserve a minority language but that continued long-term interventions will likely be necessary. We identify the parameters that determine which interventions work best under certain linguistic and societal circumstances. In this way the efficacy of interventions of various types can be identified and predicted. Although there are qualitative arguments for these parameter values (e.g., the responsiveness of children to learning a language as a function of the proportion of conversations heard in that language, the relative importance of conversations heard in the family and elsewhere, and the amplification of spoken to heard conversations of the high-status language because of the media), extensive quantitative data are lacking in this field. We propose a way to measure these parameters, allowing our model, as well as others models in the field, to be validated.

  2. Livermore Compiler Analysis Loop Suite

    SciTech Connect

    Hornung, R. D.

    2013-03-01

    LCALS is designed to evaluate compiler optimizations and performance of a variety of loop kernels and loop traversal software constructs. Some of the loop kernels are pulled directly from "Livermore Loops Coded in C", developed at LLNL (see item 11 below for details of earlier code versions). The older suites were used to evaluate floating-point performances of hardware platforms prior to porting larger application codes. The LCALS suite is geared toward assissing C++ compiler optimizations and platform performance related to SIMD vectorization, OpenMP threading, and advanced C++ language features. LCALS contains 20 of 24 loop kernels from the older Livermore Loop suites, plus various others representative of loops found in current production appkication codes at LLNL. The latter loops emphasize more diverse loop constructs and data access patterns than the others, such as multi-dimensional difference stencils. The loops are included in a configurable framework, which allows control of compilation, loop sampling for execution timing, which loops are run and their lengths. It generates timing statistics for analysis and comparing variants of individual loops. Also, it is easy to add loops to the suite as desired.

  3. NETL - Chemical Looping Reactor

    SciTech Connect

    2013-07-24

    NETL's Chemical Looping Reactor unit is a high-temperature integrated CLC process with extensive instrumentation to improve computational simulations. A non-reacting test unit is also used to study solids flow at ambient temperature. The CLR unit circulates approximately 1,000 pounds per hour at temperatures around 1,800 degrees Fahrenheit.

  4. Closing the Loop Sampler.

    ERIC Educational Resources Information Center

    California Integrated Waste Management Board, Sacramento.

    Closing the Loop (CTL) is a science curriculum designed to introduce students to integrated waste management through awareness. This document presents five lesson plans focusing on developing an understanding of natural resources, solid wastes, conservation, and the life of landfills. Contents include: (1) "What Are Natural Resources?"; (2)…

  5. NETL - Chemical Looping Reactor

    ScienceCinema

    None

    2016-07-12

    NETL's Chemical Looping Reactor unit is a high-temperature integrated CLC process with extensive instrumentation to improve computational simulations. A non-reacting test unit is also used to study solids flow at ambient temperature. The CLR unit circulates approximately 1,000 pounds per hour at temperatures around 1,800 degrees Fahrenheit.

  6. COLD TEST LOOP INTEGRATED TEST LOOP RESULTS

    SciTech Connect

    Abraham, TJ

    2003-10-22

    A testing facility (Cold Test Loop) was constructed and operated to demonstrate the efficacy of the Accelerated Waste Retrieval (AWR) Project's planned sluicing approach to the remediation of Silos 1 and 2 at the Fernald Environmental Management Project near Cincinnati, Ohio. The two silos contain almost 10,000 tons of radium-bearing low-level waste, which consists primarily of solids of raffinates from processing performed on ores from the Democratic Republic of Congo (commonly referred to as ''Belgium Congo ores'') for the recovery of uranium. These silos are 80 ft in diameter, 36 ft high to the center of the dome, and 26.75 ft to the top of the vertical side walls. The test facility contained two test systems, each designed for a specific purpose. The first system, the Integrated Test Loop (ITL), a near-full-scale plant including the actual equipment to be installed at the Fernald Site, was designed to demonstrate the sluicing operation and confirm the selection of a slurry pump, the optimal sluicing nozzle operation, and the preliminary design material balance. The second system, the Component Test Loop (CTL), was designed to evaluate many of the key individual components of the waste retrieval system over an extended run. The major results of the initial testing performed during July and August 2002 confirmed that the AWR approach to sluicing was feasible. The ITL testing confirmed the following: (1) The selected slurry pump (Hazleton 3-20 type SHW) performed well and is suitable for AWR application. However, the pump's motor should be upgraded to a 200-hp model and be driven by a 150-hp variable-frequency drive (VFD). A 200-hp VFD is not much more expensive and would allow the pump to operate at full speed. (2) The best nozzle performance was achieved by using 15/16-in. nozzles operated alternately. This configuration appeared to most effectively mine the surrogate. (3) The Solartron densitometer, which was tested as an alternative mass flow measurement

  7. Loop Heat Pipes and Capillary Pumped Loops: An Applications Perspective

    NASA Technical Reports Server (NTRS)

    Butler, Dan; Ku, Jentung; Swanson, Theodore; Obenschain, Arthur F. (Technical Monitor)

    2001-01-01

    Capillary pumped loops (CPLS) and loop heat pipes (LHPS) are versatile two-phase heat transfer devices which have recently gained increasing acceptance in space applications. Both systems work based on the same principles and have very similar designs. Nevertheless, some differences exist in the construction of the evaporator and the hydro-accumulator, and these differences lead to very distinct operating characteristics for each loop. This paper presents comparisons of the two loops from an applications perspective, and addresses their impact on spacecraft design, integration, and test. Some technical challenges and issues for both loops are also addressed.

  8. Aurora Australis, Sinuous Loop

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This view of the Aurora Australis or Southern Lights (location unknown) shows a sinuous looping band of airglow above the Earth Limb. Calculated to be in the 80 - 120 km altitude region, auroral activity is due to exitation of atomic oxygen in the upper atmosphere by radiation from the van Allen Radiation Belts and is most common above the 65 degree north and south latitude range during the spring and fall of the year.

  9. Loop Quantum Cosmology.

    PubMed

    Bojowald, Martin

    2005-01-01

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

  10. Loop Quantum Cosmology.

    PubMed

    Bojowald, Martin

    2008-01-01

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

  11. Loops of Jupiter

    NASA Astrophysics Data System (ADS)

    Opolski, Antoni

    2014-12-01

    Professor Antoni Opolski was actively interested in astronomy after his retirement in 1983. He especially liked to study the works of the famous astronomer Copernicus getting inspiration for his own work. Opolski started his work on planetary loops in 2011 continuing it to the end of 2012 . During this period calculations, drawings, tables, and basic descriptions of all the planets of the Solar System were created with the use of a piece of paper and a pencil only. In 2011 Antoni Opolski asked us to help him in editing the manuscript and preparing it for publication. We have been honored having the opportunity to work on articles on planetary loops with Antoni Opolski in his house for several months. In the middle of 2012 the detailed material on Jupiter was ready. However, professor Opolski improved the article by smoothing the text and preparing new, better drawings. Finally the article ''Loops of Jupiter'', written by the 99- year old astronomer, was published in the year of his 100th birthday.

  12. Verification of Loop Diagnostics

    NASA Technical Reports Server (NTRS)

    Winebarger, A.; Lionello, R.; Mok, Y.; Linker, J.; Mikic, Z.

    2014-01-01

    Many different techniques have been used to characterize the plasma in the solar corona: density-sensitive spectral line ratios are used to infer the density, the evolution of coronal structures in different passbands is used to infer the temperature evolution, and the simultaneous intensities measured in multiple passbands are used to determine the emission measure. All these analysis techniques assume that the intensity of the structures can be isolated through background subtraction. In this paper, we use simulated observations from a 3D hydrodynamic simulation of a coronal active region to verify these diagnostics. The density and temperature from the simulation are used to generate images in several passbands and spectral lines. We identify loop structures in the simulated images and calculate the loop background. We then determine the density, temperature and emission measure distribution as a function of time from the observations and compare with the true temperature and density of the loop. We find that the overall characteristics of the temperature, density, and emission measure are recovered by the analysis methods, but the details of the true temperature and density are not. For instance, the emission measure curves calculated from the simulated observations are much broader than the true emission measure distribution, though the average temperature evolution is similar. These differences are due, in part, to inadequate background subtraction, but also indicate a limitation of the analysis methods.

  13. International Space Station Atmosphere Control and Supply, Atmosphere Revitalization, and Water Recovery and Management Subsystem - Verification for Node 1

    NASA Technical Reports Server (NTRS)

    Williams, David E.

    2007-01-01

    The International Space Station (ISS) Node 1 Environmental Control and Life Support (ECLS) System is comprised of five subsystems: Atmosphere Control and Supply (ACS), Atmosphere Revitalization (AR), Fire Detection and Suppression (FDS), Temperature and Humidity Control (THC), and Water Recovery and Management (WRM). This paper provides a summary of the nominal operation of the Node 1 ACS, AR, and WRM design and detailed Element Verification methodologies utilized during the Qualification phase for Node 1.

  14. Floating Loop System For Cooling Integrated Motors And Inverters Using Hot Liquid Refrigerant

    DOEpatents

    Hsu, John S [Oak Ridge, TN; Ayers, Curtis W [Kingston, TN; Coomer, Chester [Knoxville, TN; Marlino, Laura D [Oak Ridge, TN

    2006-02-07

    A floating loop vehicle component cooling and air-conditioning system having at least one compressor for compressing cool vapor refrigerant into hot vapor refrigerant; at least one condenser for condensing the hot vapor refrigerant into hot liquid refrigerant by exchanging heat with outdoor air; at least one floating loop component cooling device for evaporating the hot liquid refrigerant into hot vapor refrigerant; at least one expansion device for expanding the hot liquid refrigerant into cool liquid refrigerant; at least one air conditioning evaporator for evaporating the cool liquid refrigerant into cool vapor refrigerant by exchanging heat with indoor air; and piping for interconnecting components of the cooling and air conditioning system.

  15. Air To Air Helicopter Fire Control Equations and Software Generation.

    DTIC Science & Technology

    1979-11-01

    FORM I. REPORT NUMBER 12. GOVT ACCE NO S.SCIP1INTIS CATALOG NUMBER Air To Air Helicop~ter Fire Control 1I t 31Au Equations and Software Generation oN.m...differentiator in order to model the way that they are added in the track loop before the capacitor coupled tachometer feedback. AIRSIM Data Representative output

  16. Coupled dual loop absorption heat pump

    DOEpatents

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

    1985-01-01

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

  17. Second harmonic generation and enhancement in microfibers and loop resonators

    NASA Astrophysics Data System (ADS)

    Gouveia, Marcelo A.; Lee, Timothy; Ismaeel, Rand; Ding, Ming; Broderick, Neil G. R.; Cordeiro, Cristiano M. B.; Brambilla, Gilberto

    2013-05-01

    We model and experimentally investigate second harmonic generation in silica microfibers and loop resonators, in which the second order nonlinearity arises from the glass-air surface dipole and bulk multipole contributions. In the loop resonator, the recirculation of the pump light on resonance is used to increase the conversion. The effect of the loop parameters, such as coupling and loss, is theoretically studied to determine their influence on the resonance enhancement. Experimentally, microfibers were fabricated with diameters around 0.7 μm to generate the intermodally phase matched second harmonic with an efficiency up to 4.2 × 10-8 when pumped with 5 ns 1.55 μm pulses with a peak power of 90 W. After reconfiguring the microfiber into a 1 mm diameter loop, the efficiency was resonantly enhanced by 5.7 times.

  18. Optical parametric loop mirror

    NASA Astrophysics Data System (ADS)

    Mori, K.; Morioka, T.; Saruwatari, M.

    1995-06-01

    A novel configuration for four-wave mixing (FWM) is proposed that offers the remarkable feature of inherently separating the FWM wave from the input pump and signal waves and suppressing their background amplified stimulated emission without optical filtering. In the proposed configuration, an optical parametric loop mirror, two counterpropagating FWM waves generated in a Sagnac interferometer interfere with a relative phase difference that is introduced deliberately. FWM frequency-conversion experiments in a polarization-maintaining fiber achieved more than 35 dB of input-wave suppression against the FWM wave.

  19. Closing the loop.

    PubMed

    Dassau, E; Atlas, E; Phillip, M

    2011-02-01

    Closed-loop algorithms can be found in every aspect of everyday modern life. Automation and control are used constantly to provide safety and to improve quality of life. Closed-loop systems and algorithms can be found in home appliances, automobiles, aviation and more. Can one imagine nowadays driving a car without ABS, cruise control or even anti-sliding control? Similar principles of automation and control can be used in the management of diabetes mellitus (DM). The idea of an algorithmic/technological way to control glycaemia is not new and has been researched for more than four decades. However, recent improvements in both glucose-sensing technology and insulin delivery together with advanced control and systems engineering made this dream of an artificial pancreas possible. The artificial pancreas may be the next big step in the treatment of DM since the use of insulin analogues. An artificial pancreas can be described as internal or external devices that use continuous glucose measurements to automatically manage exogenous insulin delivery with or without other hormones in an attempt to restore glucose regulation in individuals with DM using a control algorithm. This device as described can be internal or external; can use different types of control algorithms with bi-hormonal or uni-hormonal design; and can utilise different ways to administer them. The different designs and implementations have transitioned recently from in silico simulations to clinical evaluation stage with practical applications in mind. This may mark the beginning of a new era in diabetes management with the introduction of semi-closed-loop systems that can prevent or minimise nocturnal hypoglycaemia, to hybrid systems that will manage blood glucose (BG) levels with minimal user intervention to finally fully automated systems that will take the user out of the loop. More and more clinical trials will be needed for the artificial pancreas to become a reality but initial encouraging

  20. Independent Orbiter Assessment (IOA): Analysis of the atmospheric revitalization pressure control subsystem

    NASA Technical Reports Server (NTRS)

    Saiidi, M. J.; Duffy, R. E.; Mclaughlin, T. D.

    1986-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis/Critical Items List (FMEA/CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Atmospheric Revitalization and Pressure Control Subsystem (ARPCS) are documented. The ARPCS hardware was categorized into the following subdivisions: (1) Atmospheric Make-up and Control (including the Auxiliary Oxygen Assembly, Oxygen Assembly, and Nitrogen Assembly); and (2) Atmospheric Vent and Control (including the Positive Relief Vent Assembly, Negative Relief Vent Assembly, and Cabin Vent Assembly). The IOA analysis process utilized available ARPCS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

  1. Space shuttle atmospheric revitalization subsystem/active thermal control subsystem computer program (users manual)

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A shuttle (ARS) atmosphere revitalization subsystem active thermal control subsystem (ATCS) performance routine was developed. This computer program is adapted from the Shuttle EC/LSS Design Computer Program. The program was upgraded in three noteworthy areas: (1) The functional ARS/ATCS schematic has been revised to accurately synthesize the shuttle baseline system definition. (2) The program logic has been improved to provide a more accurate prediction of the integrated ARS/ATCS system performance. Additionally, the logic has been expanded to model all components and thermal loads in the ARS/ATCS system. (3) The program is designed to be used on the NASA JSC crew system division's programmable calculator system. As written the new computer routine has an average running time of five minutes. The use of desk top type calculation equipment, and the rapid response of the program provides the NASA with an analytical tool for trade studies to refine the system definition, and for test support of the RSECS or integrated Shuttle ARS/ATCS test programs.

  2. The revitalization of health and education in Rural America Act of 1992

    NASA Technical Reports Server (NTRS)

    English, Glenn

    1991-01-01

    During the preceding decade of the 1980's, rural communities witnessed an exodus of over 5 million residents to urban and suburban areas of the nation. It has become increasingly clear that rural parts of the country must adopt aggressive strategies to strengthen rural communities and enhance the quality of life for its citizens into the 21st century. Studies by the U.S. Department of Commerce, Office of Technology Assessment, and the Aspen Institute all identify advanced telecommunications systems as the linchpin for a vigorous future for rural America. The Revitalization of Health and Education in Rural America Act of 1992 incorporates these recommendations into viable strategies to improve health care and educational services for rural citizens. By linking up hospitals and schools through advanced telecommunications technology, vast geographic distances are instantly reduced. With the proper infrastructure in place, up-to-date telecommunications services will facilitate endless opportunities for improving the quality of life in remote areas. This comprehensive legislation is the critical first step in forging a partnership with urban communities to create an economically sound and technologically advanced America for generations to come. Improvement of health care and educational services in rural areas through the implementation of interactive telecommunications systems is addressed. A copy of the Act is included.

  3. International Space Station Program Phase 3 Integrated Atmosphere Revitalization Subsystem Test

    NASA Technical Reports Server (NTRS)

    Perry, J. L.; Franks, G. D.; Knox, J. C.

    1997-01-01

    Testing of the International Space Station (ISS) U.S. Segment baseline configuration of the Atmosphere Revitalization Subsystem (ARS) by NASA's Marshall Space Flight Center (MSFC) was conducted as part of the Environmental Control and Life Support System (ECLSS) design and development program. This testing was designed to answer specific questions regarding the control and performance of the baseline ARS subassemblies in the ISS U.S. Segment configuration. These questions resulted from the continued maturation of the ISS ECLSS configuration and design requirement changes since 1992. The test used pressurized oxygen injection, a mass spectrometric major constituent analyzer, a Four-Bed Molecular Sieve Carbon Dioxide Removal Assembly, and a Trace Contaminant Control Subassembly to maintain the atmospheric composition in a sealed chamber at ISS specifications for 30 days. Human metabolic processes for a crew of four were simulated according to projected ISS mission time lines. The performance of a static feed water electrolysis Oxygen Generator Assembly was investigated during the test preparation phases; however, technical difficulties prevented its use during the integrated test. The Integrated ARS Test (IART) program built upon previous closed-door and open-door integrated testing conducted at MSFC between 1987 and 1992. It is the most advanced test of an integrated ARS conducted by NASA to demonstrate its end-to-end control and overall performance. IART test objectives, facility design, pretest analyses, test and control requirements, and test results are presented.

  4. Norwegian public health policy: revitalization of the social democratic welfare state?

    PubMed

    Fosse, Elisabeth

    2009-01-01

    Norway is part of the so-called social democratic welfare state model, which is characterized by its emphasis on solidarity and redistribution among social groups. The concepts of upstream and downstream policy measures may be useful to characterize different approaches to public health policies: upstream measures would be structural measures, in line with the social democratic welfare state model, while downstream measures would be more targeted at individuals or groups at some sort of risk. The aim of this article is to analyze national policies in Norway and how these may be characterized in terms of upstream and downstream factors. Health promotion and public health policies have been high on the Norwegian political agenda for two decades. However, the national policy emphasis has shifted between strategies aimed at individuals and structural strategies--that is, between downstream and upstream measures. Until 2003, policies included mainly downstream measures, but since then a policy shift has taken place and current policy includes an emphasis on upstream measures. This policy was strengthened after a left-wing coalition came into government in 2005. It may be argued that the present policy represents a revitalization of universal and structural measures, in line with the social democratic welfare state model.

  5. Design and Performance of the Sorbent-Based Atmosphere Revitalization System for Orion

    NASA Technical Reports Server (NTRS)

    Ritter, James A.; Reynolds, Steven P.; Ebner, Armin D.; Knox, James C.; LeVan, M. Douglas

    2007-01-01

    Validation and simulations of a real-time dynamic cabin model were conducted on the sorbent-based atmosphere revitalization system for Orion. The dynamic cabin model, which updates the concentration of H2O and CO2 every second during the simulation, was able to predict the steady state model values for H2O and CO2 for long periods of steady metabolic production for a 4-person crew. It also showed similar trends for the exercise periods, where there were quick changes in production rates. Once validated, the cabin model was used to determine the effects of feed flow rate, cabin volume and column volume. A higher feed flow rate reduced the cabin concentrations only slightly over the base case, a larger cabin volume was able to reduce the cabin concentrations even further, and the lower column volume led to much higher cabin concentrations. Finally, the cabin model was used to determine the effect of the amount of silica gel in the column. As the amount increased, the cabin concentration of H2O decreased, but the cabin concentration of CO2 increased.

  6. Loop expansion and the bosonic representation of loop quantum gravity

    NASA Astrophysics Data System (ADS)

    Bianchi, E.; Guglielmon, J.; Hackl, L.; Yokomizo, N.

    2016-10-01

    We introduce a new loop expansion that provides a resolution of the identity in the Hilbert space of loop quantum gravity on a fixed graph. We work in the bosonic representation obtained by the canonical quantization of the spinorial formalism. The resolution of the identity gives a tool for implementing the projection of states in the full bosonic representation onto the space of solutions to the Gauss and area matching constraints of loop quantum gravity. This procedure is particularly efficient in the semiclassical regime, leading to explicit expressions for the loop expansions of coherent, heat kernel and squeezed states.

  7. High temperature storage loop :

    SciTech Connect

    Gill, David Dennis; Kolb, William J.

    2013-07-01

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

  8. Ekpyrotic loop quantum cosmology

    SciTech Connect

    Wilson-Ewing, Edward

    2013-08-01

    We consider the ekpyrotic paradigm in the context of loop quantum cosmology. In loop quantum cosmology the classical big-bang singularity is resolved due to quantum gravity effects, and so the contracting ekpyrotic branch of the universe and its later expanding phase are connected by a smooth bounce. Thus, it is possible to explicitly determine the evolution of scalar perturbations, from the contracting ekpyrotic phase through the bounce and to the post-bounce expanding epoch. The possibilities of having either one or two scalar fields have been suggested for the ekpyrotic universe, and both cases will be considered here. In the case of a single scalar field, the constant mode of the curvature perturbations after the bounce is found to have a blue spectrum. On the other hand, for the two scalar field ekpyrotic model where scale-invariant entropy perturbations source additional terms in the curvature perturbations, the power spectrum in the post-bounce expanding cosmology is shown to be nearly scale-invariant and so agrees with observations.

  9. The double loop mattress suture

    PubMed Central

    Biddlestone, John; Samuel, Madan; Creagh, Terry; Ahmad, Tariq

    2014-01-01

    An interrupted stitch type with favorable tissue characteristics will reduce local wound complications. We describe a novel high-strength, low-tension repair for the interrupted closure of skin, cartilage, and muscle, the double loop mattress stitch, and compare it experimentally with other interrupted closure methods. The performance of the double loop mattress technique in porcine cartilage and skeletal muscle is compared with the simple, mattress, and loop mattress interrupted sutures in both a novel porcine loading chamber and mechanical model. Wound apposition is assessed by electron microscopy. The performance of the double loop mattress in vivo was confirmed using a series of 805 pediatric laparotomies/laparoscopies. The double loop mattress suture is 3.5 times stronger than the loop mattress in muscle and 1.6 times stronger in cartilage (p ≤ 0.001). Additionally, the double loop mattress reduces tissue tension by 66% compared with just 53% for the loop mattress (p ≤ 0.001). Wound gapping is equal, and wound eversion appears significantly improved (p ≤ 0.001) compared with the loop mattress in vitro. In vivo, the double loop mattress performs as well as the loop mattress and significantly better than the mattress stitch in assessments of wound eversion and dehiscence. There were no episodes of stitch extrusion in our series of patients. The mechanical advantage of its intrinsic pulley arrangement gives the double loop mattress its favorable properties. Wound dehiscence is reduced because this stitch type is stronger and exerts less tension on the tissue than the mattress stitch. We advocate the use of this novel stitch wherever a high-strength, low-tension repair is required. These properties will enhance wound repair, and its application will be useful to surgeons of all disciplines. PMID:24698436

  10. Enhancement of surface nonwettability by grafting loops.

    PubMed

    Pei, Han-Wen; Liu, Xiao-Li; Liu, Hong; Zhu, You-Liang; Lu, Zhong-Yuan

    2017-02-08

    We present a computer simulation study on the nonwettability of a flat surface tethered with deformable looped polymer chains. Two kinds of loops are studied: monodispersed loops (loops with the same length) and polydispersed loops (loops with different lengths). Both kinds of loops include two arrangements: with regularly tethered sites and with randomly tethered sites. Regularly grafted loops form typical grooves on the surface, while randomly grafted loops form a more rugged surface. For monodispersed loops, we analyze the factors that influence the nonwettability when varying the rigidity of the loops. The loops are divided into two categories based on their rigidity according to our previous analysis procedure (Phys. Chem. Chem. Phys., 2016, 18, 18767-18775): rigid loops and flexible loops. It is found that the loop can partially form a re-entrant-like structure, which is helpful to increase the nonwettability of the surface. The surfaces with grafted loops have increased nonwettability, especially those grafted with flexible chains. However, the contact angle on the loop structure cannot further increase for the rigid chains due to a large top layer density (Phys. Chem. Chem. Phys., 2016, 18, 18767-18775). For polydispersed loops, the contact angle is highly related to the rigidity of the long loops that contact the droplet. Different from monodispersed loops, the mechanism of the nonwettability of polydispersed loops is attributed to the supporting ability (rigidity) of long loops.

  11. Unstable anisotropic loop quantum cosmology

    SciTech Connect

    Nelson, William; Sakellariadou, Mairi

    2009-09-15

    We study stability conditions of the full Hamiltonian constraint equation describing the quantum dynamics of the diagonal Bianchi I model in the context of loop quantum cosmology. Our analysis has shown robust evidence of an instability in the explicit implementation of the difference equation, implying important consequences for the correspondence between the full loop quantum gravity theory and loop quantum cosmology. As a result, one may question the choice of the quantization approach, the model of lattice refinement, and/or the role of the ambiguity parameters; all these should, in principle, be dictated by the full loop quantum gravity theory.

  12. Loop Heat Pipe Startup Behaviors

    NASA Technical Reports Server (NTRS)

    Ku, Jentung

    2016-01-01

    A loop heat pipe must start successfully before it can commence its service. The startup transient represents one of the most complex phenomena in the loop heat pipe operation. This paper discusses various aspects of loop heat pipe startup behaviors. Topics include the four startup scenarios, the initial fluid distribution between the evaporator and reservoir that determines the startup scenario, factors that affect the fluid distribution between the evaporator and reservoir, difficulties encountered during the low power startup, and methods to enhance the startup success. Also addressed are the pressure spike and pressure surge during the startup transient, and repeated cycles of loop startup and shutdown under certain conditions.

  13. Assessment of internal contamination problems associated with bioregenerative air/water purification systems

    NASA Technical Reports Server (NTRS)

    Johnson, Anne H.; Bounds, B. Keith; Gardner, Warren

    1990-01-01

    The emphasis is to characterize the mechanisms of bioregenerative revitalization of air and water as well as to assess the possible risks associated with such a system in a closed environment. Marsh and aquatic plants are utilized for purposes of wastewater treatment as well as possible desalinization and demineralization. Foliage plants are also being screened for their ability to remove toxic organics from ambient air. Preliminary test results indicate that treated wastewater is typically of potable quality with numbers of pathogens such as Salmonella and Shigella significantly reduced by the artificial marsh system. Microbiological analyses of ambient air indicate the presence of bacilli as well as thermophilic actinomycetes.

  14. Loop-the-Loop: Bringing Theory into Practice

    ERIC Educational Resources Information Center

    Suwonjandee, N.; Asavapibhop, B.

    2012-01-01

    During the Thai high-school physics teacher training programme, we used an aluminum loop-the-loop system built by the Institute for the Promotion of Teaching Science and Technology (IPST) to demonstrate a circular motion and investigate the concept of the conservation of mechanical energy. There were 27 high-school teachers from three provinces,…

  15. Test Capabilities Revitalization at the Aerial Cable Test Facility, Sandia National Laboratories, New Mexico

    DTIC Science & Technology

    2003-06-01

    AFFECTED ENVIRONMENT 3.1 History The original aerial cable, installed in 1971, was a 1 3/8-inch wire rope spanning a 5,000-ft-wide canyon. A rocket sled... cableways . 3.2 Air Quality Ambient air quality is regulated by the joint Albuquerque-Bernalillo County-Air Quality Control Board (ABC/AQCB). The ABC

  16. Dynamic PID loop control

    SciTech Connect

    Pei, L.; Klebaner, A.; Theilacker, J.; Soyars, W.; Martinez, A.; Bossert, R.; DeGraff, B.; Darve, C.; /Fermilab

    2011-06-01

    The Horizontal Test Stand (HTS) SRF Cavity and Cryomodule 1 (CM1) of eight 9-cell, 1.3GHz SRF cavities are operating at Fermilab. For the cryogenic control system, how to hold liquid level constant in the cryostat by regulation of its Joule-Thompson JT-valve is very important after cryostat cool down to 2.0 K. The 72-cell cryostat liquid level response generally takes a long time delay after regulating its JT-valve; therefore, typical PID control loop should result in some cryostat parameter oscillations. This paper presents a type of PID parameter self-optimal and Time-Delay control method used to reduce cryogenic system parameters oscillation.

  17. Pulse thermal loop

    NASA Technical Reports Server (NTRS)

    Weislogel, Mark M. (Inventor)

    2002-01-01

    A pulse thermal loop heat transfer system includes a means to use pressure rises in a pair of evaporators to circulate a heat transfer fluid. The system includes one or more valves that iteratively, alternately couple the outlets the evaporators to the condenser. While flow proceeds from one of the evaporators to the condenser, heating creates a pressure rise in the other evaporator, which has its outlet blocked to prevent fluid from exiting the other evaporator. When the flow path is reconfigured to allow flow from the other evaporator to the condenser, the pressure in the other evaporator is used to circulate a pulse of fluid through the system. The reconfiguring of the flow path, by actuating or otherwise changing the configuration of the one or more valves, may be triggered when a predetermined pressure difference between the evaporators is reached.

  18. Vortex loops and Majoranas

    SciTech Connect

    Chesi, Stefano; Jaffe, Arthur; Loss, Daniel; Pedrocchi, Fabio L.

    2013-11-15

    We investigate the role that vortex loops play in characterizing eigenstates of interacting Majoranas. We give some general results and then focus on ladder Hamiltonian examples as a test of further ideas. Two methods yield exact results: (i) A mapping of certain spin Hamiltonians to quartic interactions of Majoranas shows that the spectra of these two examples coincide. (ii) In cases with reflection-symmetric Hamiltonians, we use reflection positivity for Majoranas to characterize vortices in the ground states. Two additional methods suggest wider applicability of these results: (iii) Numerical evidence suggests similar behavior for certain systems without reflection symmetry. (iv) A perturbative analysis also suggests similar behavior without the assumption of reflection symmetry.

  19. The use of superoxide mixtures as air-revitalization chemicals in hyperbaric, self-contained, closed-circuit breathing apparatus

    NASA Technical Reports Server (NTRS)

    Wood, P. C.; Wydeven, T.

    1985-01-01

    In portable breathing apparatus applications at 1 atm, potassium superoxide (KO2) has exhibited low-utilization efficiency of the available oxygen (O2) and diminished carbon dioxide-(CO2) scrubbing capacity caused by the formation of a fused, hydrated-hydroxide/carbonate product coating on the superoxide granules. In earlier work, it was discovered that granules fabricated from an intimate mixture of KO2 and calcium superoxide, Ca(O2)2, did not exhibit formation of a fused product coating and the utilization efficiency with respect to both O2 release and CO2 absorption was superior to KO2 granules when both types of granules were reacted with humidified CO2 under identified conditions. In the work described here, single pellets of KO2, KO2/Ca(O2), mixtures and commercially available KO2 tables and granules were reacted with a flow of humidified CO2 in helium at 1- and 10-atm total pressure and at an initial temperature of 40 C. In the 1-atm flow tests, the reaction rates and utilization efficiency of the KO2/Ca(O2)2 pellets were markedly superior to the KO2 pellets, tablets, and granules when the samples were reacted under identical conditions. However, at 10 atm, the rates of O2 release and CO2 absorption, as well as the utilization efficiencies of all the superoxide samples, were one-third to one-eighth of the values observed at 1 atm. The decrease in reaction performance at 10 atm compared to that at 1 atm has been attributed principally to the lower bulk diffusivity of the CO2 and H2O reactants in helium at the higher pressure and secondarily to the moderation of the reaction temperature caused by the higher heat capacity of the 10-atm helium.

  20. Loop Quantum Gravity.

    PubMed

    Rovelli, Carlo

    2008-01-01

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

  1. Uranyl Nitrate Flow Loop

    SciTech Connect

    Ladd-Lively, Jennifer L

    2008-10-01

    The objectives of the work discussed in this report were to: (1) develop a flow loop that would simulate the purified uranium-bearing aqueous stream exiting the solvent extraction process in a natural uranium conversion plant (NUCP); (2) develop a test plan that would simulate normal operation and disturbances that could be anticipated in an NUCP; (3) use the flow loop to test commercially available flowmeters for use as safeguards monitors; and (4) recommend a flowmeter for production-scale testing at an NUCP. There has been interest in safeguarding conversion plants because the intermediate products [uranium dioxide (UO{sub 2}), uranium tetrafluoride (UF{sub 4}), and uranium hexafluoride (UF{sub 6})] are all suitable uranium feedstocks for producing special nuclear materials. Furthermore, if safeguards are not applied virtually any nuclear weapons program can obtain these feedstocks without detection by the International Atomic Energy Agency (IAEA). Historically, IAEA had not implemented safeguards until the purified UF{sub 6} product was declared as feedstock for enrichment plants. H. A. Elayat et al. provide a basic definition of a safeguards system: 'The function of a safeguards system on a chemical conversion plant is in general terms to verify that no useful nuclear material is being diverted to use in a nuclear weapons program'. The IAEA now considers all highly purified uranium compounds as candidates for safeguarding. DOE is currently interested in 'developing instruments, tools, strategies, and methods that could be of use to the IAEA in the application of safeguards' for materials found in the front end of the nuclear fuel cycle-prior to the production of the uranium hexafluoride or oxides that have been the traditional starting point for IAEA safeguards. Several national laboratories, including Oak Ridge, Los Alamos, Lawrence Livermore, and Brookhaven, have been involved in developing tools or techniques for safeguarding conversion plants. This study

  2. Native Skywatchers - Revitalization of Ojibwe & D(L)akota Star Knowledge - Collaborative Work with Educators

    NASA Astrophysics Data System (ADS)

    Lee, Annette S.; Gawboy, Carl; Rock, Jim; Tibbetts, Jeff; Wilson, William; O'Rourke, Charlene

    2015-08-01

    In Ojibwe culture we look towards the Evening Star and honor Ikwe’ Anung - the Woman’s Star. In D(L)akota culture in addition to seeing the dragon, Draco in the northern circumpolar skies, we recognize Wakiyan - the Thunderbird, located at the center of the precession circle. Woven into the native star knowledge are important and insightful understandings of astronomical patterns and phenomenon that are too valuable to be forgotten. This living relationship with the cosmos is a core part of the cultural history and present day heritage of native people.Native Skywatchers is an indigenous led initiative to revitalize and rebuild the star knowledge of the Ojibwe and D(L)akota peoples. Right now is a critical time; much has been lost. At the same time, there is a tremendous demand and excitement for this knowledge.Growing momentum is due in part to the MN State K-12 Science Standards (2009) that requires educators to teach how: “Men and women throughout the history of all cultures, including Minnesota American Indian tribes and communities, have been involved in engineering design and scientific inquiry.” Specifically Benchmark 3.1.3.2.1 states, “For example: Ojibwe and Dakota knowledge and use of patterns in the stars to predict and plan”.This important work has many branches: interdisciplinary connections in science and culture, formal and informal science education, artwork and art programming, history and heritage, outreach and community wellness.The focus of this presentation will be collaborative work done with educators. The aim has been expanding the work from cultural heritage into classroom curriculum while preserving the cultural integrity. This has been accomplished by two primary factors: 1.) the development of resources such as: native star maps, planispheres, constellation guidebooks, artwork, curriculum; 2.) dissemination and exchange with regional educators, including the state office of the Minnesota Department of Education.

  3. A Multifaceted Approach to Revitalizing the Baby-Friendly Hospital Initiative in Croatia.

    PubMed

    Grgurić, Josip; Zakarija-Grković, Irena; Pavičić Bošnjak, Anita; Stanojević, Milan

    2016-08-01

    The Baby-Friendly Hospital Initiative (BFHI) was launched in Croatia in 1993. By 1998, 15 of 34 maternity facilities were designated "Baby-Friendly." Introduction of hospital bags, violating the International Code of the Marketing of Breastmilk Substitutes, led to a standstill in the BFHI. The aim of this article is to describe the successful reintroduction of the BFHI in Croatia between 2007 and 2015. After hospital bags were abolished in 2007, UNICEF Croatia undertook an assessment of BFHI implementation. All maternity facilities were invited by UNICEF and the Ministry of Health to join the renewed BFHI. UNICEF materials were translated and training for trainers, assessors, coordinators, and hospital staff held. By June 2015, 30 of 32 (94%) maternity facilities, providing care to 89% of newborns, were Baby-Friendly. Nine maternity hospitals have been renovated and 2 new hospitals have been built. Exclusive breastfeeding rates have risen 16% at 0 to 2 months (from 51% in 2007 to 67% in 2014) and 14% at 3 to 5 months (from 32% in 2007 to 46% in 2014). Fourteen "Breastfeeding-Friendly" primary care practices have been designated, 166 breastfeeding support groups are in operation, criteria for Mother-Friendly care are being piloted in 2 maternity facilities, and "Ten Steps in the Neonatal Intensive Care Unit" are being introduced. The BFHI provides an excellent opportunity for revitalizing breastfeeding protection, promotion, and support in all settings. Recognition and support of the BFHI by the Croatian government was crucial for implementing the BFHI, whereas the marketing practices of the breast milk substitutes industry are an ongoing challenge.

  4. Revitalization of clinical skills training at the University of the Western Cape.

    PubMed

    Jeggels, J D; Traut, A; Kwast, M

    2010-06-01

    Most educational institutions that offer health related qualifications make use of clinical skills laboratories. These spaces are generally used for the demonstration and assessment of clinical skills. The purpose of this paper is to share our experiences related to the revitalization of skills training by introducing the skills lab method at the School of Nursing (SoN), University of the Western Cape (UWC). To accommodate the contextual changes as a result of the restructuring of the higher education landscape in 2003, the clinical skills training programme at UWC had to be reviewed. With a dramatic increase in the student numbers and a reduction in hospital beds, the skills lab method provided students with an opportunity to develop clinical skills prior to their placement in real service settings. The design phase centred on adopting a skills training methodology that articulates with the case-based approach used by the SoN. Kolb's, experiential learning cycle provided the theoretical underpinning for the methodology. The planning phase was spent on the development of resources. Eight staff members were trained by our international higher education collaborators who also facilitated the training of clinical supervisors and simulated patients. The physical space had to be redesigned to accommodate audio visual and information technology to support the phases of the skills lab method. The implementation of the skills lab method was phased in from the first-year level. An interactive seminar held after the first year of implementation provided feedback from all the role players and was mostly positive. The results of introducing the skills lab method include: a move by students towards self-directed clinical skills development, clinical supervisors adopting the role of facilitators of learning and experiential clinical learning being based on, amongst others, the students' engagement with simulated patients. Finally, the recommendations relate to tailor

  5. The Projectile Inside the Loop

    ERIC Educational Resources Information Center

    Varieschi, Gabriele U.

    2006-01-01

    The loop-the-loop demonstration can be easily adapted to study the kinematics of projectile motion, when the moving body falls inside the apparatus. Video capturing software can be used to reveal peculiar geometrical effects of this simple but educational experiment.

  6. RCD+: Fast loop modeling server

    PubMed Central

    López-Blanco, José Ramón; Canosa-Valls, Alejandro Jesús; Li, Yaohang; Chacón, Pablo

    2016-01-01

    Modeling loops is a critical and challenging step in protein modeling and prediction. We have developed a quick online service (http://rcd.chaconlab.org) for ab initio loop modeling combining a coarse-grained conformational search with a full-atom refinement. Our original Random Coordinate Descent (RCD) loop closure algorithm has been greatly improved to enrich the sampling distribution towards near-native conformations. These improvements include a new workflow optimization, MPI-parallelization and fast backbone angle sampling based on neighbor-dependent Ramachandran probability distributions. The server starts by efficiently searching the vast conformational space from only the loop sequence information and the environment atomic coordinates. The generated closed loop models are subsequently ranked using a fast distance-orientation dependent energy filter. Top ranked loops are refined with the Rosetta energy function to obtain accurate all-atom predictions that can be interactively inspected in an user-friendly web interface. Using standard benchmarks, the average root mean squared deviation (RMSD) is 0.8 and 1.4 Å for 8 and 12 residues loops, respectively, in the challenging modeling scenario in where the side chains of the loop environment are fully remodeled. These results are not only very competitive compared to those obtained with public state of the art methods, but also they are obtained ∼10-fold faster. PMID:27151199

  7. Improved code-tracking loop

    NASA Technical Reports Server (NTRS)

    Laflame, D. T.

    1980-01-01

    Delay-locked loop tracks pseudonoise codes without introducing dc timing errors, because it is not sensitive to gain imbalance between signal processing arms. "Early" and "late" reference codes pass in combined form through both arms, and each arm acts on both codes. Circuit accomodates 1 dB weaker input signals with tracking ability equal to that of tau-dither loops.

  8. Revitalization of an Immature Permanent Mandibular Molar with a Necrotic Pulp Using Platelet-Rich Fibrin: A Case Report

    PubMed Central

    Shoba, Krishnamma; Aman, Shibu; Bharkavi, Srinivasan Kumar Indu

    2016-01-01

    Any insult to the pulp during its development causes cessation of dentin formation and root growth. Pulpal status and degree of root development are the decisive factors in the treatment approach. Various treatment options have been tried like surgery with root-end sealing, calcium hydroxide–apexification, placement of apical plug and regenerative endodontic procedures to induce apexogenesis. An ideal scenario for a necrosed tooth with immature root would be continued root development coupled with regeneration of pulp tissue. We report a case, where revitalization was done using Platelet-Rich Fibrin (PRF) as a scaffold in immature mandibular molar tooth. PMID:28050518

  9. Wilson Loop Diagrams and Positroids

    NASA Astrophysics Data System (ADS)

    Agarwala, Susama; Marin-Amat, Eloi

    2017-03-01

    In this paper, we study a new application of the positive Grassmannian to Wilson loop diagrams (or MHV diagrams) for scattering amplitudes in N= 4 Super Yang-Mill theory ( N = 4 SYM). There has been much interest in studying this theory via the positive Grassmannians using BCFW recursion. This is the first attempt to study MHV diagrams for planar Wilson loop calculations (or planar amplitudes) in terms of positive Grassmannians. We codify Wilson loop diagrams completely in terms of matroids. This allows us to apply the combinatorial tools in matroid theory used to identify positroids (non-negative Grassmannians) to Wilson loop diagrams. In doing so, we find that certain non-planar Wilson loop diagrams define positive Grassmannians. While non-planar diagrams do not have physical meaning, this finding suggests that they may have value as an algebraic tool, and deserve further investigation.

  10. Loop-bed combustion apparatus

    DOEpatents

    Shang, Jer-Yu; Mei, Joseph S.; Slagle, Frank D.; Notestein, John E.

    1984-01-01

    The present invention is directed to a combustion apparatus in the configuration of a oblong annulus defining a closed loop. Particulate coal together with a sulfur sorbent such as sulfur or dolomite is introduced into the closed loop, ignited, and propelled at a high rate of speed around the loop. Flue gas is withdrawn from a location in the closed loop in close proximity to an area in the loop where centrifugal force imposed upon the larger particulate material maintains these particulates at a location spaced from the flue gas outlet. Only flue gas and smaller particulates resulting from the combustion and innerparticle grinding are discharged from the combustor. This structural arrangement provides increased combustion efficiency due to the essentially complete combustion of the coal particulates as well as increased sulfur absorption due to the innerparticle grinding of the sorbent which provides greater particle surface area.

  11. Loop Heat Pipe Startup Behaviors

    NASA Technical Reports Server (NTRS)

    Ku, Jentung

    2014-01-01

    A loop heat pipe must start successfully before it can commence its service. The start-up transient represents one of the most complex phenomena in the loop heat pipe operation. This paper discusses various aspects of loop heat pipe start-up behaviors. Topics include the four start-up scenarios, the initial fluid distribution between the evaporator and reservoir that determines the start-up scenario, factors that affect the fluid distribution between the evaporator and reservoir, difficulties encountered during the low power start-up, and methods to enhance the start-up success. Also addressed are the thermodynamic constraint between the evaporator and reservoir in the loop heat pipe operation, the superheat requirement for nucleate boiling, pressure spike and pressure surge during the start-up transient, and repeated cycles of loop start-up andshutdown under certain conditions.

  12. Higher dimensional loop quantum cosmology

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangdong

    2016-07-01

    Loop quantum cosmology (LQC) is the symmetric sector of loop quantum gravity. In this paper, we generalize the structure of loop quantum cosmology to the theories with arbitrary spacetime dimensions. The isotropic and homogeneous cosmological model in n+1 dimensions is quantized by the loop quantization method. Interestingly, we find that the underlying quantum theories are divided into two qualitatively different sectors according to spacetime dimensions. The effective Hamiltonian and modified dynamical equations of n+1 dimensional LQC are obtained. Moreover, our results indicate that the classical big bang singularity is resolved in arbitrary spacetime dimensions by a quantum bounce. We also briefly discuss the similarities and differences between the n+1 dimensional model and the 3+1 dimensional one. Our model serves as a first example of higher dimensional loop quantum cosmology and offers the possibility to investigate quantum gravity effects in higher dimensional cosmology.

  13. Modeling loop entropy.

    PubMed

    Chirikjian, Gregory S

    2011-01-01

    Proteins fold from a highly disordered state into a highly ordered one. Traditionally, the folding problem has been stated as one of predicting "the" tertiary structure from sequential information. However, new evidence suggests that the ensemble of unfolded forms may not be as disordered as once believed, and that the native form of many proteins may not be described by a single conformation, but rather an ensemble of its own. Quantifying the relative disorder in the folded and unfolded ensembles as an entropy difference may therefore shed light on the folding process. One issue that clouds discussions of "entropy" is that many different kinds of entropy can be defined: entropy associated with overall translational and rotational Brownian motion, configurational entropy, vibrational entropy, conformational entropy computed in internal or Cartesian coordinates (which can even be different from each other), conformational entropy computed on a lattice, each of the above with different solvation and solvent models, thermodynamic entropy measured experimentally, etc. The focus of this work is the conformational entropy of coil/loop regions in proteins. New mathematical modeling tools for the approximation of changes in conformational entropy during transition from unfolded to folded ensembles are introduced. In particular, models for computing lower and upper bounds on entropy for polymer models of polypeptide coils both with and without end constraints are presented. The methods reviewed here include kinematics (the mathematics of rigid-body motions), classical statistical mechanics, and information theory.

  14. Air and water quality monitor assessment of life support subsystems

    NASA Technical Reports Server (NTRS)

    Whitley, Ken; Carrasquillo, Robyn L.; Holder, D.; Humphries, R.

    1988-01-01

    Preprotype air revitalization and water reclamation subsystems (Mole Sieve, Sabatier, Static Feed Electrolyzer, Trace Contaminant Control, and Thermoelectric Integrated Membrane Evaporative Subsystem) were operated and tested independently and in an integrated arrangement. During each test, water and/or gas samples were taken from each subsystem so that overall subsystem performance could be determined. The overall test design and objectives for both subsystem and integrated subsystem tests were limited, and no effort was made to meet water or gas specifications. The results of chemical analyses for each of the participating subsystems are presented along with other selected samples which were analyzed for physical properties and microbiologicals.

  15. Wilson loops in minimal surfaces

    SciTech Connect

    Drukker, Nadav; Gross, David J.; Ooguri, Hirosi

    1999-04-27

    The AdS/CFT correspondence suggests that the Wilson loop of the large N gauge theory with N = 4 supersymmetry in 4 dimensions is described by a minimal surface in AdS{sub 5} x S{sup 5}. The authors examine various aspects of this proposal, comparing gauge theory expectations with computations of minimal surfaces. There is a distinguished class of loops, which the authors call BPS loops, whose expectation values are free from ultra-violet divergence. They formulate the loop equation for such loops. To the extent that they have checked, the minimal surface in AdS{sub 5} x S{sup 5} gives a solution of the equation. The authors also discuss the zig-zag symmetry of the loop operator. In the N = 4 gauge theory, they expect the zig-zag symmetry to hold when the loop does not couple the scalar fields in the supermultiplet. They will show how this is realized for the minimal surface.

  16. Digital phase-locked loop

    NASA Technical Reports Server (NTRS)

    Cliff, R. A. (Inventor)

    1975-01-01

    An digital phase-locked loop is provided for deriving a loop output signal from an accumulator output terminal. A phase detecting exclusive OR gate is fed by the loop digital input and output signals. The output of the phase detector is a bi-level digital signal having a duty cycle indicative of the relative phase of the input and output signals. The accumulator is incremented at a first rate in response to a first output level of the phase detector and at a second rate in response to a second output level of the phase detector.

  17. Open loop distribution system design

    SciTech Connect

    Glamocanin, V. ); Filipovic, V. . Elektrotechnicki fakulet)

    1993-10-01

    The ability to supply consumers of an urban area, with minimum interruption during a feeder segment or substation transformer outage, is assured by a uniform cable size of the feeder segments along the entire loop. Based on the criterion of the uniform cable size, a loop configuration is obtained first by minimizing the installation costs, and then an open loop solution is found by minimizing the power losses. Heuristic rules are proposed and used to obtain an initial solution, as well as to improve current solutions.

  18. Optical loop framing

    SciTech Connect

    Kalibjian, R.; Chong, Y.P.; Prono, D.S.; Cavagnolo, H.R.

    1984-06-01

    The ATA provides an electron beam pulse of 70-ns duration at a 1-Hz rate. Our present optical diagnostics technique involve the imaging of the visible light generated by the beam incident onto the plant of a thin sheet of material. It has already been demonstrated that the light generated has a sufficiently fast temporal reponse in performing beam diagnostics. Notwithstanding possible beam emittance degradation due to scattering in the thin sheet, the observation of beam spatial profiles with relatively high efficiencies has provided data complementary to that obtained from beam wall current monitors and from various x-ray probes and other electrical probes. The optical image sensor consists of a gated, intensified television system. The gate pulse of the image intensifier can be appropriately delayed to give frames that are time-positioned from the head to the tail of the beam with a minimum gate time of 5-ns. The spatial correlation of the time frames from pulse to pulse is very good for a stable electron beam; however, when instabilities do occur, it is difficult to properly assess the spatial composition of the head and the tail of the beam on a pulse-to-pulse basis. Multiple gating within a pulse duration becomes desirable but cannot be performed because the recycle time (20-ms) of the TV system is much longer than the beam pulse. For this reason we have developed an optical-loop framing technique that will allow the recording of two frames within one pulse duration with our present gated/intensified TV system.

  19. Loop Electrosurgical Excision Procedure (LEEP)

    MedlinePlus

    ... that acts like a scalpel (surgical knife). An electric current is passed through the loop, which cuts away ... A procedure in which an instrument works with electric current to destroy tissue. Local Anesthesia: The use of ...

  20. Integrated optical phase locked loop.

    SciTech Connect

    Lentine, Anthony L.; Kim, Jungwon; Trotter, Douglas Chandler; DeRose, Christopher T.; Kartner, Franz X.; Byun, Hyunil; Nejadmalayeri, Amir H.; Watts, Michael R.; Zortman, William A.

    2010-12-01

    A silicon photonics based integrated optical phase locked loop is utilized to synchronize a 10.2 GHz voltage controlled oscillator with a 509 MHz mode locked laser, achieving 32 fs integrated jitter over 300 kHz bandwidth.

  1. SDO Sees Flourishing Magnetic Loops

    NASA Video Gallery

    A bright set of loops near the edge of the sun’s face grew and shifted quickly after the magnetic field was disrupted by a small eruption on Nov. 25, 2015. Charged particles emitting light in extre...

  2. SDO Sees Brightening Magnetic Loops

    NASA Video Gallery

    Two active regions sprouted arches of bundled magnetic loops in this video from NASA’s Solar Dynamics Observatory taken on Nov. 11-12, 2015. Charged particles spin along the magnetic field, tracing...

  3. Observations of loops and prominences

    NASA Technical Reports Server (NTRS)

    Strong, Keith T.

    1994-01-01

    We review recent observations by the Yohkoh-SXT (Soft X-ray Telescope) in collaboration with other spacecraft and ground-based observatories of coronal loops and prominences. These new results point to problems that SoHO will be able to address. With a unique combination of rapid-cadence digital imaging (greater than or equal to 32 s full-disk and greater than or equal to 2 s partial-frame images), high spatial resolution (greater than or equal to 2.5 arcsec pixels), high sensitivity (EM less than or equal to 10(exp 42) cm(exp -3)), a low-scatter mirror, and large dynamic range, SXT can observe a vast range of targets on the Sun. Over the first 21 months of Yohkoh operations SXT has taken over one million images of the corona and so is building up an invaluable long-term database on the large-scale corona and loop geometry. The most striking thing about the SXT images is the range of loop sizes and shapes. The active regions are a bright tangle of magnetic field lines, surrounded by a network of large-scale quiet-Sun loops stretching over distances in excess of 105 km. The cross-section of most loops seems to be constant. Loops displaying significant Gamma's are the exception, not the rule, implying the presence of widespread currents in the corona. All magnetic structures show changes. Time scales range from seconds to months. The question of how these structures are formed, become filled with hot plasma, and are maintained is still open. While we see the propagation of brightenings along the length of active-region loops and in X-ray jets with velocities of several hundred km/s, much higher velocities are seen in the quiet Sun. In XBP flares, for example, velocities of over 1000 km/s are common. Active-region loops seem to be in constant motion, moving slowly outward, carrying plasma with them. During flares, loops often produce localized brightenings at the base and later at the apex of the loop. Quiescent filaments and prominences have been observed regularly

  4. LETS: An Expressional Loop Notation.

    DTIC Science & Technology

    1982-10-01

    r - ..’ -rI- x- - r ,11 V~ The Expressional Metaphor 2- Waters i "The Expressional Metaphor ’lhe key property of expressions which makes them...development of a notation which has the property of decomposability. Viewing Loops as Expressions Involving Sequences In order to represent loops as...a DEFUNS or LETS. For example, the function EPLIST takes in a discnbodied plist and returns two values: a sequence of the property names. and a

  5. Closed loop spray cooling apparatus

    NASA Technical Reports Server (NTRS)

    Alger, D. L.; Schwab, W. B.; Furman, E. R. (Inventor)

    1979-01-01

    A closed loop apparatus for jet spraying coolant against the back of a radiation target is described. The coolant is circulated through a closed loop with a bubble of inert gas being maintained around the spray. Mesh material is disposed between the bubble and the surface of the liquid coolant which is below the bubble at a predetermined level. In a second arrangement no inert gas is used, the bubble consists of vapor produced when the coolant is sprayed against the target.

  6. High temperature loop heat pipes

    SciTech Connect

    Anderson, W.G.; Bland, J.J.; Fershtater, Y.; Goncharov, K.A.; Nikitkin, M.; Juhasz, A.

    1995-12-31

    Advantages of loop heat pipes over conventional heat pipes include self-priming during start-up, improved tolerance for noncondensible gas, and ability for ground testing in any orientation. The applications for high temperature, alkali-metal working fluid loop heat pipes include space radiators, and bimodal systems. A high temperature loop heat pipe was fabricated and tested at 850 K, using cesium as the working fluid. Previous loop heat pipes were tested with ambient temperature working fluids at temperatures below about 450 K. The loop heat pipe had a titanium envelope, and a titanium aluminide wick. The maximum cesium loop heat pipe power was only about 600 watts, which was lower the predicted 1,000 W power. The power limitation may be due to a wettability problem with the cesium not completely wetting the titanium aluminide wick. This would reduce the pumping capability of the wick, and the maximum power that the heat pipe could carry. This problem could be solved by using a refractory metal powder wick, since the alkali metals are known to wet refractory metal wicks.

  7. THE CORONAL LOOP INVENTORY PROJECT

    SciTech Connect

    Schmelz, J. T.; Pathak, S.; Christian, G. M.; Dhaliwal, R. S. S.; Paul, K. S.

    2015-11-01

    Most coronal physicists now seem to agree that loops are composed of tangled magnetic strands and have both isothermal and multithermal cross-field temperature distributions. As yet, however, there is no information on the relative importance of each of these categories, and we do not know how common one is with respect to the other. In this paper, we investigate these temperature properties for all loop segments visible in the 171-Å image of AR 11294, which was observed by the Atmospheric Imaging Assembly (AIA) on 2011 September 15. Our analysis revealed 19 loop segments, but only 2 of these were clearly isothermal. Six additional segments were effectively isothermal, that is, the plasma emission to which AIA is sensitive could not be distinguished from isothermal emission, within measurement uncertainties. One loop had both isothermal transition region and multithermal coronal solutions. Another five loop segments require multithermal plasma to reproduce the AIA observations. The five remaining loop segments could not be separated reliably from the background in the crucial non-171-Å AIA images required for temperature analysis. We hope that the direction of coronal heating models and the efforts modelers spend on various heating scenarios will be influenced by these results.

  8. Loop Models from SOHO Observations

    NASA Astrophysics Data System (ADS)

    Landini, M.; Brković , A.; Landi, E.; Rüedi, I.; Solanki, S.

    1999-01-01

    The Coronal Diagnostic Spectrometer (CDS) on SOHO is a grazing/normal incidence spectrograph, aimed to produce stigmatic spectra of selected regions of the solar surface in six spectral windows of the extreme ultraviolet from 150 Å to 785 Å (Harrison et al. 1995). In the present work, CDS, EIT, MDI and Yohkoh observations of active region lops have been analyzed. These observations are part of JOP 54. CDS monochromatic images from lines at different temperatures have been co-aligned with EIT and MDI images, and loop structures have been clearly identified using Fe XVI emission lines. Density sensitive lines and lines from adjacent stages of ionization of Fe ions have been used to measure electron density and temperature along the loop length; these measurements have been used to determine the electron pressure along the loop and test the constant pressure assumption commonly used in loop modeling. The observations have been compared with a static, isobaric loop model (Landini and Monsignori Fossi 1975) assuming a temperature-constant heating function in the energy balance equation. Good agreement is found for the temperature distribution along the loop at the coronal level. The model pressure is somewhat higher than obtained from density sensitive line ratios.

  9. A Narrative Inquiry of Technology as a Viable Support to Revitalizing and Increasing the Choctaw Language among American Indians and Non-Indians in an Early Childhood Setting

    ERIC Educational Resources Information Center

    McClour, Christine Elizabeth

    2015-01-01

    In the past several decades the global village has witnessed a rapid decline in the number of indigenous languages. This study was a narrative inquiry within a qualitative methodology. Two research questions were used to analyze the narratives of Choctaw Nation Head Start teachers concerning technology usage for increasing, and revitalizing the…

  10. US-German Cooperation For Further Development Of Decision Support Systems For Sustainable Contaminated Site Revitalization - Berlin, Germany, Sept. 24, 2008.

    EPA Science Inventory

    SMARTe (Sustainable Management Approaches and Revitalization Tools - electronic) is a web-based decision support tool developed by the Office of Research and Development (ORD) in partnership with the Office of Brownfields and Land Revital...

  11. Air Research

    EPA Pesticide Factsheets

    EPA's air research provides the critical science to develop and implement outdoor air regulations under the Clean Air Act and puts new tools and information in the hands of air quality managers and regulators to protect the air we breathe.

  12. Performance of Silica Gel in the Role of Residual Air Drying

    NASA Technical Reports Server (NTRS)

    Jan, Darrell L.; Hogan, John A.; Koss, Brian; Palmer, Gary H.; Richardson, Justine; Linggi, Paul

    2014-01-01

    Removal of carbon dioxide (CO2) is a necessary step in air revitalization and is often accomplished with sorbent materials. Since moisture competes with CO2 in sorbent materials, it is necessary to remove the water first. This is typically accomplished in two stages: bulk removal and residual drying. Silica gel is used as the bulk drying material in the Carbon Dioxide Removal Assembly (CDRA) in operation on ISS. There has been some speculation that silica gel may also be capable of serving as the residual drying material. This paper will describe test apparatus and procedures for determining the performance of silica gel in residual air drying.

  13. Xerox's closed recycling loop still contains kinks

    SciTech Connect

    Not Available

    1995-02-01

    Xerox Corp. has established a recycling loop for plastics screw-top toner bottles and dry-ink containers used in most of the company's high-volume copiers. However, a severe shortage of post-consumer recycled plastic has been short-circuiting Xerox's good intentions. Last year, the Stamford, Conn.-based company stopped manufacturing toner containers from virgin plastics and instead began using recycled raw materials, such as discarded milk and water jugs collected from municipal curbside recycling programs. The bottles are ground and remolded into such products as air filters for vacuum cleaners, plastic lumber, compost bins, landscape ties, benches and fence posts. However, what sounds like a win-win situation actually is costing too much money. Contrary to popular belief, post-consumer recycled plastic costs more than virgin plastic. Despite the added expense, Xerox will continue to use recycled plastics when possible.

  14. Filter for third order phase locked loops

    NASA Technical Reports Server (NTRS)

    Crow, R. B.; Tausworthe, R. C. (Inventor)

    1973-01-01

    Filters for third-order phase-locked loops are used in receivers to acquire and track carrier signals, particularly signals subject to high doppler-rate changes in frequency. A loop filter with an open-loop transfer function and set of loop constants, setting the damping factor equal to unity are provided.

  15. Kalman Orbit Optimized Loop Tracking

    NASA Technical Reports Server (NTRS)

    Young, Lawrence E.; Meehan, Thomas K.

    2011-01-01

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

  16. Predictive Techniques for Spacecraft Cabin Air Quality Control

    NASA Technical Reports Server (NTRS)

    Perry, J. L.; Cromes, Scott D. (Technical Monitor)

    2001-01-01

    As assembly of the International Space Station (ISS) proceeds, predictive techniques are used to determine the best approach for handling a variety of cabin air quality challenges. These techniques use equipment offgassing data collected from each ISS module before flight to characterize the trace chemical contaminant load. Combined with crew metabolic loads, these data serve as input to a predictive model for assessing the capability of the onboard atmosphere revitalization systems to handle the overall trace contaminant load as station assembly progresses. The techniques for predicting in-flight air quality are summarized along with results from early ISS mission analyses. Results from groundbased analyses of in-flight air quality samples are compared to the predictions to demonstrate the technique's relative conservatism.

  17. Study of the open loop and closed loop oscillator techniques

    SciTech Connect

    Baker, Benjamin; Riley, Tony; Langbehn, Adam; Imel, George R.; Benzerga, M. Lamine; Aryal, Harishchandra

    2015-07-01

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

  18. Lattice calculation of the Polyakov loop and Polyakov loop correlators

    NASA Astrophysics Data System (ADS)

    Weber, Johannes Heinrich

    2017-03-01

    We discuss calculations of the Polyakov loop and of Polyakov loop correlators using lattice gauge theory. We simulate QCD with 2+1 flavors and almost physical quark masses using the highly improved staggered quark action (HISQ).We demonstrate that the entropy derived from the Polyakov loop is a good probe of color screening. In particular, it allows for scheme independent and quantitative conclusions about the deconfinement aspects of the crossover and for a rigorous study of the onset of weak-coupling behavior at high temperatures. We examine the correlators for small and large separations and identify vacuum-like and screening regimes in the thermal medium. We demonstrate that gauge-independent screening properties can be obtained even from gauge-fixed singlet correlators and that we can pin down the asymptotic regime.

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

    SciTech Connect

    Imel, George R.; Baker, Benjamin; Riley, Tony; Langbehn, Adam; Aryal, Harishchandra; Benzerga, M. Lamine

    2015-04-11

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

  20. Loop coupled resonator optical waveguides.

    PubMed

    Song, Junfeng; Luo, Lian-Wee; Luo, Xianshu; Zhou, Haifeng; Tu, Xiaoguang; Jia, Lianxi; Fang, Qing; Lo, Guo-Qiang

    2014-10-06

    We propose a novel coupled resonator optical waveguide (CROW) structure that is made up of a waveguide loop. We theoretically investigate the forbidden band and conduction band conditions in an infinite periodic lattice. We also discuss the reflection- and transmission- spectra, group delay in finite periodic structures. Light has a larger group delay at the band edge in a periodic structure. The flat band pass filter and flat-top group delay can be realized in a non-periodic structure. Scattering matrix method is used to calculate the effects of waveguide loss on the optical characteristics of these structures. We also introduce a tunable coupling loop waveguide to compensate for the fabrication variations since the coupling coefficient of the directional coupler in the loop waveguide is a critical factor in determining the characteristics of a loop CROW. The loop CROW structure is suitable for a wide range of applications such as band pass filters, high Q microcavity, and optical buffers and so on.

  1. Bandwidth controller for phase-locked-loop

    NASA Technical Reports Server (NTRS)

    Brockman, Milton H. (Inventor)

    1992-01-01

    A phase locked loop utilizing digital techniques to control the closed loop bandwidth of the RF carrier phase locked loop in a receiver provides high sensitivity and a wide dynamic range for signal reception. After analog to digital conversion, a digital phase locked loop bandwidth controller provides phase error detection with automatic RF carrier closed loop tracking bandwidth control to accommodate several modes of transmission.

  2. Digital phase-lock loop

    NASA Technical Reports Server (NTRS)

    Thomas, Jr., Jess B. (Inventor)

    1991-01-01

    An improved digital phase lock loop incorporates several distinctive features that attain better performance at high loop gain and better phase accuracy. These features include: phase feedback to a number-controlled oscillator in addition to phase rate; analytical tracking of phase (both integer and fractional cycles); an amplitude-insensitive phase extractor; a more accurate method for extracting measured phase; a method for changing loop gain during a track without loss of lock; and a method for avoiding loss of sampled data during computation delay, while maintaining excellent tracking performance. The advantages of using phase and phase-rate feedback are demonstrated by comparing performance with that of rate-only feedback. Extraction of phase by the method of modeling provides accurate phase measurements even when the number-controlled oscillator phase is discontinuously updated.

  3. Many Ways to Loop DNA

    PubMed Central

    Griffith, Jack D.

    2013-01-01

    In the 1960s, I developed methods for directly visualizing DNA and DNA-protein complexes using an electron microscope. This made it possible to examine the shape of DNA and to visualize proteins as they fold and loop DNA. Early applications included the first visualization of true nucleosomes and linkers and the demonstration that repeating tracts of adenines can cause a curvature in DNA. The binding of DNA repair proteins, including p53 and BRCA2, has been visualized at three- and four-way junctions in DNA. The trombone model of DNA replication was directly verified, and the looping of DNA at telomeres was discovered. PMID:24005675

  4. All digital pulsewidth control loop

    NASA Astrophysics Data System (ADS)

    Huang, Hong-Yi; Jan, Shiun-Dian; Pu, Ruei-Iun

    2013-03-01

    This work presents an all-digital pulsewidth control loop (ADPWCL). The proposed system accepts a wide range of input duty cycles and performs a fast correction to the target output pulsewidth. An all-digital delay-locked loop (DLL) with fast locking time using a simplified time to digital converter and a new differential two-step delay element is proposed. The area of the delay element is much smaller than that in conventional designs, while having the same delay range. A test chip is verified in a 0.18-µm CMOS process. The measured duty cycle ranges from 4% to 98% with 7-bit resolution.

  5. Reionization from cosmic string loops

    SciTech Connect

    Olum, Ken D.; Vilenkin, Alexander

    2006-09-15

    Loops formed from a cosmic string network at early times would act as seeds for early formation of halos, which would form galaxies and lead to early reionization. With reasonable guesses about astrophysical and string parameters, the cosmic string scale G{mu} must be no more than about 3x10{sup -8} to avoid conflict with the reionization redshift found by WMAP. The bound is much stronger for superstring models with a small string reconnection probability. For values near the bound, cosmic string loops may explain the discrepancy between the WMAP value and theoretical expectations.

  6. Regional Approach And Tools For Sustainable Revitalization, Documentation Of A Workshop Of The U.S.-German Bilateral Working Group, May 8 And 9, 2008 - New York, New York

    EPA Science Inventory

    There is growing international recognition that revitalization of regions containing potentially contaminated sites to meet economic, environmental/ecological, and social/cultural demands can and should contribute to the sustainability of the human and natural environment by impr...

  7. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, ... Ozone, a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  8. Closed-Loop Neuromorphic Benchmarks

    PubMed Central

    Stewart, Terrence C.; DeWolf, Travis; Kleinhans, Ashley; Eliasmith, Chris

    2015-01-01

    Evaluating the effectiveness and performance of neuromorphic hardware is difficult. It is even more difficult when the task of interest is a closed-loop task; that is, a task where the output from the neuromorphic hardware affects some environment, which then in turn affects the hardware's future input. However, closed-loop situations are one of the primary potential uses of neuromorphic hardware. To address this, we present a methodology for generating closed-loop benchmarks that makes use of a hybrid of real physical embodiment and a type of “minimal” simulation. Minimal simulation has been shown to lead to robust real-world performance, while still maintaining the practical advantages of simulation, such as making it easy for the same benchmark to be used by many researchers. This method is flexible enough to allow researchers to explicitly modify the benchmarks to identify specific task domains where particular hardware excels. To demonstrate the method, we present a set of novel benchmarks that focus on motor control for an arbitrary system with unknown external forces. Using these benchmarks, we show that an error-driven learning rule can consistently improve motor control performance across a randomly generated family of closed-loop simulations, even when there are up to 15 interacting joints to be controlled. PMID:26696820

  9. Telomeres thrown for a loop.

    PubMed

    Haber, James E

    2004-11-19

    A remarkable paper from the de Lange lab (Wang et al., 2004) in a recent issue of Cell reveals that homologous recombination can result in the abrupt shortening of telomeres in a process that appears to involve reciprocal crossing over within the t-loop structure that protects chromosome ends.

  10. Bimodal loop-gap resonator

    NASA Astrophysics Data System (ADS)

    Piasecki, W.; Froncisz, W.; Hyde, James S.

    1996-05-01

    A bimodal loop-gap resonator for use in electron paramagnetic resonance (EPR) spectroscopy at S band is described. It consists of two identical one-loop-one-gap resonators in coaxial juxtaposition. In one mode, the currents in the two loops are parallel and in the other antiparallel. By introducing additional capacitors between the loops, the frequencies of the two modes can be made to coincide. Details are given concerning variable coupling to each mode, tuning of the resonant frequency of one mode to that of the other, and adjustment of the isolation between modes. An equivalent circuit is given and network analysis carried out both experimentally and theoretically. EPR applications are described including (a) probing of the field distributions with DPPH, (b) continuous wave (cw) EPR with a spin-label line sample, (c) cw electron-electron double resonance (ELDOR), (d) modulation of saturation, and (e) saturation-recovery (SR) EPR. Bloch induction experiments can be performed when the sample extends half way through the structure, but microwave signals induced by Mx and My components of magnetization cancel when it extends completely through. This latter situation is particularly favorable for SR, modulation of saturation, and ELDOR experiments, which depend on observing Mz indirectly using a second weak observing microwave source.

  11. Ponderomotive Acceleration in Coronal Loops

    NASA Astrophysics Data System (ADS)

    Dahlburg, R. B.; Laming, J. M.; Taylor, B. D.; Obenschain, K.

    2016-11-01

    Ponderomotive acceleration has been asserted to be a cause of the first ionization potential (FIP) effect, the well-known enhancement in abundance by a factor of 3-4 over photospheric values of elements in the solar corona with FIP less than about 10 eV. It is shown here by means of numerical simulations that ponderomotive acceleration occurs in solar coronal loops, with the appropriate magnitude and direction, as a “by-product” of coronal heating. The numerical simulations are performed with the HYPERION code, which solves the fully compressible three-dimensional magnetohydrodynamic equations including nonlinear thermal conduction and optically thin radiation. Numerical simulations of coronal loops with an axial magnetic field from 0.005 to 0.02 T and lengths from 25,000 to 75,000 km are presented. In the simulations the footpoints of the axial loop magnetic field are convected by random, large-scale motions. There is a continuous formation and dissipation of field-aligned current sheets, which act to heat the loop. As a consequence of coronal magnetic reconnection, small-scale, high-speed jets form. The familiar vortex quadrupoles form at reconnection sites. Between the magnetic footpoints and the corona the reconnection flow merges with the boundary flow. It is in this region that the ponderomotive acceleration occurs. Mirroring the character of the coronal reconnection, the ponderomotive acceleration is also found to be intermittent.

  12. Loop quantum cosmology gravitational baryogenesis

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2016-11-01

    Loop quantum cosmology is an appealing quantum completion of classical cosmology, which brings along various theoretical features which in many cases offer a remedy for or modify various classical cosmology aspects. In this paper we address the gravitational baryogenesis mechanism in the context of loop quantum cosmology. As we demonstrate, when loop quantum cosmology effects are taken into account in the resulting Friedmann equations for a flat Friedmann-Robertson-Walker Universe, then even for a radiation-dominated Universe, the predicted baryon-to-entropy ratio from the gravitational baryogenesis mechanism is non-zero, in contrast to the Einstein-Hilbert case, in which case the baryon-to-entropy ratio is zero. We also discuss various other cases apart from the radiation domination case, and we discuss how the baryon-to-entropy ratio is affected from the parameters of the quantum theory. In addition, we use illustrative exact solutions of loop quantum cosmology and we investigate under which circumstances the baryon-to-entropy ratio can be compatible with the observational constraints.

  13. Closed-Loop Hierarchical Control of Military Air Operations

    DTIC Science & Technology

    2002-07-01

    necessary to allow the replication of experimental conditions and to provide other aspects of a systematic experimentation environment. Pilots are...compare the performance of the optimal integer programming solution. Second, it provides optimal or near- optimal candidate missions for conditions ...represented by stochastic models using pseudorandom numbers. This is necessary to allow the replication of experimental conditions and to provide other

  14. Evolution in a Braided Loop Ensemble

    NASA Video Gallery

    This braided loop has several loops near the 'base' that appear to be unwinding with significant apparent outflow. This is evidence of untwisting, and the braided structure also seeming to unwind w...

  15. Optimum design of hybrid phase locked loops

    NASA Technical Reports Server (NTRS)

    Lee, P.; Yan, T.

    1981-01-01

    The design procedure of phase locked loops is described in which the analog loop filter is replaced by a digital computer. Specific design curves are given for the step and ramp input changes in phase. It is shown that the designed digital filter depends explicitly on the product of the sampling time and the noise bandwidth of the phase locked loop. This technique of optimization can be applied to the design of digital analog loops for other applications.

  16. Fragmentation of cosmic-string loops

    NASA Technical Reports Server (NTRS)

    York, Thomas

    1989-01-01

    The fragmentation of cosmic string loops is discussed, and the results of a simulation of this process are presented. The simulation can evolve any of a large class of loops essentially exactly, including allowing fragments that collide to join together. Such reconnection enhances the production of small fragments, but not drastically. With or without reconnections, the fragmentation process produces a collection of nonself-intersecting loops whose typical length is on the order of the persistence length of the initial loop.

  17. An Approach for Hydrogen Recycling in a Closed-loop Life Support Architecture to Increase Oxygen Recovery Beyond State-of-the-Art

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Miller, Lee; Greenwood, Zachary; Alvarez, Giraldo

    2014-01-01

    State-of-the-art atmosphere revitalization life support technology on the International Space Station is theoretically capable of recovering 50% of the oxygen from metabolic carbon dioxide via the Carbon Dioxide Reduction Assembly (CRA). When coupled with a Plasma Pyrolysis Assembly (PPA), oxygen recovery increases dramatically, thus drastically reducing the logistical challenges associated with oxygen resupply. The PPA decomposes methane to predominantly form hydrogen and acetylene. Because of the unstable nature of acetylene, a down-stream separation system is required to remove acetylene from the hydrogen stream before it is recycled to the CRA. A new closed-loop architecture that includes a PPA and downstream Hydrogen Purification Assembly (HyPA) is proposed and discussed. Additionally, initial results of separation material testing are reported.

  18. Teachers' Perception of Looping in Secondary Schools

    ERIC Educational Resources Information Center

    Chakey, Dennis J.

    2014-01-01

    The purpose of this qualitative study was to gain an understanding of secondary teachers' perception of the looping process. The research questions revealed teachers' opinions of the looping process and its impact on the overall educational experience. Participants within this study had experiences teaching within the looping process and within a…

  19. Data-aided carrier tracking loops

    NASA Technical Reports Server (NTRS)

    Lindsey, W. C.; Simon, M. K.

    1973-01-01

    Power in composite signal sidebands is used to enhance signal-to-noise ratio in carrier tracking loop, thereby reducing radio loss and decreasing probability of receiver error. By adding quadrature channel to phase-lock-loop detector circuit of receiver, dc component can be fed back into carrier tracking loop.

  20. Loop connectors in dentogenic diastema

    PubMed Central

    Nayar, Sanjna; Jayesh, Raghevendra; Venkateshwaran; Dinakarsamy, V.

    2015-01-01

    Patients with a missing tooth along with diastema have limited treatment options to restore the edentulous space. The use of a conventional fixed partial denture (FPD) to replace the missing tooth may result in too wide anterior teeth leading to poor esthetics. Loss of anterior teeth with existing diastema may result in excess space available for pontic. This condition presents great esthetic challenge for prosthodontist. If implant supported prosthesis is not possible because of inadequate bone support, FPD along with loop connector may be a treatment option to maintain the diastema and provide optimal esthetic restoration. Here, we report a clinical case where FPD along with loop connector was used to achieve esthetic rehabilitation in maxillary anterior region in which midline diastema has been maintained. PMID:26015732

  1. Microgyroscope with closed loop output

    NASA Technical Reports Server (NTRS)

    Challoner, A. Dorian (Inventor); Gutierrez, Roman C. (Inventor); Tang, Tony K. (Inventor); Cargille, Donald R. (Inventor)

    2002-01-01

    A micro-gyroscope (10) having closed loop operation by a control voltage (V.sub.TY), that is demodulated by an output signal of the sense electrodes (S1, S2), providing Coriolis torque rebalance to prevent displacement of the micro-gyroscope (10) on the output axis (y-axis). The present invention provides wide-band, closed-loop operation for a micro-gyroscope (10) and allows the drive frequency to be closely tuned to a high Q sense axis resonance. A differential sense signal (S1-S2) is compensated and fed back by differentially changing the voltage on the drive electrodes to rebalance Coriolis torque. The feedback signal is demodulated in phase with the drive axis signal (K.sub..omega..crclbar..sub.x) to produce a measure of the Coriolis force.

  2. Grain boundary loops in graphene

    NASA Astrophysics Data System (ADS)

    Cockayne, Eric; Rutter, Gregory M.; Guisinger, Nathan P.; Crain, Jason N.; First, Phillip N.; Stroscio, Joseph A.

    2011-05-01

    Topological defects can affect the physical properties of graphene in unexpected ways. Harnessing their influence may lead to enhanced control of both material strength and electrical properties. Here we present a class of topological defects in graphene composed of a rotating sequence of dislocations that close on themselves, forming grain boundary loops that either conserve the number of atoms in the hexagonal lattice or accommodate vacancy or interstitial reconstruction, while leaving no unsatisfied bonds. One grain boundary loop is observed as a “flower” pattern in scanning tunneling microscopy studies of epitaxial graphene grown on SiC(0001). We show that the flower defect has the lowest energy per dislocation core of any known topological defect in graphene, providing a natural explanation for its growth via the coalescence of mobile dislocations.

  3. Loop Variables in String Theory

    NASA Astrophysics Data System (ADS)

    Sathiapalan, B.

    The loop variable approach is a proposal for a gauge-invariant generalization of the sigma-model renormalization group method of obtaining equations of motion in string theory. The basic guiding principle is space-time gauge invariance rather than world sheet properties. In essence it is a version of Wilson's exact renormalization group equation for the world sheet theory. It involves all the massive modes and is defined with a finite world sheet cutoff, which allows one to go off the mass-shell. On shell the tree amplitudes of string theory are reproduced. The equations are gauge-invariant off shell also. This paper is a self-contained discussion of the loop variable approach as well as its connection with the Wilsonian RG.

  4. DNA Looping, Supercoiling and Tension

    NASA Astrophysics Data System (ADS)

    Finzi, Laura

    2007-11-01

    In complex organisms, activation or repression of gene expression by proteins bound to enhancer or silencer elements located several kilobases away from the promoter is a well recognized phenomenon. However, a mechanistic understanding of any of these multiprotein interactions is still incomplete. Part of the difficulty in characterizing long-range interactions is the complexity of the regulatory systems and also an underestimation of the effect of DNA supercoiling and tension. Supercoiling is expected to promote interactions between DNA sites because it winds the DNA into compact plectonemes in which distant DNA segments more frequently draw close. The idea that DNA is also under various levels of tension is becoming more widely accepted. Forces that stretch the double helix in vivo are the electrostatic repulsion among the negatively charged phosphate groups along the DNA backbone, the action of motor enzymes perhaps acting upon a topologically constrained sequence of DNA or chromosome segregation during cell mitosis following DNA replication. Presently, little is known about the tension acting on DNA in vivo, but characterization of how physiological regulatory processes, such as loop formation, depend on DNA tension in vitro will indicate the stretching force regimes likely to exist in vivo. In this light, the well studied CI protein of bacteriophage l, which was recently found to cause a of 3.8 kbp loop in DNA, is an ideal system in which to characterize long-range gene regulation. The large size of the loop lends itself to single-molecule techniques, which allow characterization of the dynamics of CI-mediated l DNA looping under controlled levels of supercoiling and tension. Such experiments are being used to discover the principles of long-range interactions in l and in more complex systems.

  5. Loops in inflationary correlation functions

    NASA Astrophysics Data System (ADS)

    Tanaka, Takahiro; Urakawa, Yuko

    2013-12-01

    We review the recent progress regarding the loop corrections to the correlation functions in the inflationary universe. A naive perturbation theory predicts that the loop corrections generated during inflation suffer from various infrared (IR) pathologies. Introducing an IR cutoff by hand is neither satisfactory nor enough to fix the problem of a secular growth, which may ruin the predictive power of inflation models if the inflation lasts sufficiently long. We discuss the origin of the IR divergences and explore the regularity conditions of the loop corrections for the adiabatic perturbation, the iso-curvature perturbation, and the tensor perturbation, in turn. These three kinds of perturbations have qualitative differences, but in discussing the IR regularity there is a feature common to all cases, which is the importance of the proper identification of observable quantities. Genuinely, observable quantities should respect the gauge invariance from the view point of a local observer. Interestingly, we find that the requirement of the IR regularity restricts the allowed quantum states.

  6. Dynamic Aperture-based Solar Loop Segmentation

    NASA Technical Reports Server (NTRS)

    Lee, Jon Kwan; Newman, Timothy S.; Gary, G. Allen

    2006-01-01

    A new method to automatically segment arc-like loop structures from intensity images of the Sun's corona is introduced. The method constructively segments credible loop structures by exploiting the Gaussian-like shape of loop cross-sectional intensity profiles. The experimental results show that the method reasonably segments most of the well-defined loops in coronal images. The method is only the second published automated solar loop segmentation method. Its advantage over the other published method is that it operates independently of supplemental time specific data.

  7. Modeling Phase-Locked Loops Using Verilog

    DTIC Science & Technology

    2007-11-01

    a charge pump, the phase detector has a tri-state output that can drive a opamp loop filter directly. This signal is conditioned by the charge pump...then it can directly drive an opamp based loop filter. Most loop filters are based upon an integrator loop. The integrator loop filter is advantageous...replaced with an accumulator. The opamp circuit can be replaced by a digital filter using Z-transform theory z=exp(jwT), where T is the sampling

  8. Hyperstaticity and loops in frictional granular packings

    NASA Astrophysics Data System (ADS)

    Tordesillas, Antoinette; Lam, Edward; Metzger, Philip T.

    2009-06-01

    The hyperstatic nature of granular packings of perfectly rigid disks is analyzed algebraically and through numerical simulation. The elementary loops of grains emerge as a fundamental element in addressing hyperstaticity. Loops consisting of an odd number of grains behave differently than those with an even number. For odd loops, the latent stresses are exterior and are characterized by the sum of frictional forces around each loop. For even loops, the latent stresses are interior and are characterized by the alternating sum of frictional forces around each loop. The statistics of these two types of loop sums are found to be Gibbsian with a "temperature" that is linear with the friction coefficient μ when μ<1.

  9. High-temperature helium-loop facility

    SciTech Connect

    Tokarz, R.D.

    1981-09-01

    The high-temperature helium loop is a facility for materials testing in ultrapure helium gas at high temperatures. The closed loop system is capable of recirculating high-purity helium or helium with controlled impurities. The gas loop maximum operating conditions are as follows: 300 psi pressure, 500 lb/h flow rate, and 2100/sup 0/F temperature. The two test sections can accept samples up to 3.5 in. diameter and 5 ft long. The gas loop is fully instrumented to continuously monitor all parameters of loop operation as well as helium impurities. The loop is fully automated to operate continuously and requires only a daily servicing by a qualified operator to replenish recorder charts and helium makeup gas. Because of its versatility and high degree of parameter control, the helium loop is applicable to many types of materials research. This report describes the test apparatus, operating parameters, peripheral systems, and instrumentation system.

  10. Chemical Looping Technology: Oxygen Carrier Characteristics.

    PubMed

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

    2015-01-01

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

  11. Chemical Looping Combustion Reactions and Systems

    SciTech Connect

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

    2011-07-01

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

  12. Dirac Loops in Carbon Allotropes

    NASA Astrophysics Data System (ADS)

    Mullen, Kieran; Uchoa, Bruno; Glatzhofer, D.

    2015-03-01

    We propose a family of structures that have ``Dirac loops'': closed lines in momentum space with Dirac-like quasiparticles, on which the density of states vanishes linearly with energy. The structures all possess the planar trigonal connectivity present in graphene, but are three dimensional. We discuss the consequences of their multiply-connected Fermi surface for transport, including the presence of three dimensional Integer Quantum Hall effect. In the presence of spin-orbit coupling, we show that those structures may have topological surface states. We discuss the feasibility of realizing the structures as an allotrope of carbon. Work supported by NSF Grants DMR-1310407 and DMR-1352604.

  13. Singularities in loop quantum cosmology.

    PubMed

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

    2008-12-19

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

  14. Magnetic monopole in the loop representation

    SciTech Connect

    Leal, Lorenzo; Lopez, Alexander

    2006-01-15

    We quantize, within the Loop Representation formalism, the electromagnetic field in the presence of a static magnetic pole. It is found that the loop-dependent physical wave functionals of the quantum Maxwell theory become multivalued, through a topological phase factor depending on the solid angle subtended at the monopole by a surface bounded by the loop. It is discussed how this fact generalizes what occurs in ordinary quantum mechanics in multiply connected spaces.

  15. LMFBR with booster pump in pumping loop

    DOEpatents

    Rubinstein, H.J.

    1975-10-14

    A loop coolant circulation system is described for a liquid metal fast breeder reactor (LMFBR) utilizing a low head, high specific speed booster pump in the hot leg of the coolant loop with the main pump located in the cold leg of the loop, thereby providing the advantages of operating the main pump in the hot leg with the reliability of cold leg pump operation.

  16. Catheterization of Intestinal Loops in Ruminants Does Not Adversely Affect Loop Function

    PubMed Central

    Inglis, G Douglas; Kastelic, John P; Uwiera, Richard R E

    2010-01-01

    Catheterized intestinal loops may be a valuable model to elucidate key components of the host response to various treatments within the small intestine of ruminants. We examined whether catheterizing ileal loops in sheep affected the overall health of animals and intestinal function, whether a bacterial treatment could be introduced into the loops through the catheters, and whether broad-spectrum antibiotics could sterilize the loops. Escherichia coli cells transformed to express the GFP gene were introduced readily into the loops through the catheters, and GFP E. coli cells were localized within the injected loops. Catheterized loops, interspaces, and intact ileum exhibited no abnormalities in tissue appearance or electrical resistance. Expression of the IFNγ, IL1α, IL4, IL6, IL12p40, IL18, TGFβ1, and TNFα cytokine genes did not differ significantly among the intact ileum, catheterized loops, and interspaces, nor did the expression of the gene for inducible nitric oxide synthase. Broad-spectrum antibiotics administered during surgery did not sterilize the loops or interspaces and did not substantively change the composition of the microbiota. However, antibiotics reduced the overall number of bacterial cells within the loop and the relative abundance of community constituents. We concluded that catheterization of intestinal loops did not adversely affect health or loop function in sheep. Furthermore, allowing animals to recover fully from surgery and to clear pharmaceuticals will remove any confounding effects due to these factors, making catheterized intestinal loops a feasible model for studying host responses in ruminants. PMID:21262134

  17. Multi-instrument observations of coronal loops

    NASA Astrophysics Data System (ADS)

    Scott, Jason Terrence

    This document exhibits results of analysis from data collected with multiple EUV satellites (SOHO, TRACE, STEREO, Hinode, and SDO). The focus is the detailed observation of coronal loops using multiple instruments, i.e. filter imagers and spectrometers. Techniques for comparing the different instruments and deriving loop parameters are demonstrated. Attention is given to the effects the different instruments may introduce into the data and their interpretation. The assembled loop parameters are compared to basic energy balance equations and scaling laws. Discussion of the blue-shifted, asymmetric, and line broadened spectral line profiles near the footpoints of coronal loops is made. The first quantitative analysis of the anti-correlation between intensity and spectral line broadening for isolated regions along loops and their footpoints is presented. A magnetic model of an active region shows where the separatrices meet the photospheric boundary. At the boundary, the spectral data reveal concentrated regions of increased blue-shifted outflows, blue wing asymmetry, and line broadening. This is found just outside the footpoints of bright loops. The intensity and line broadening in this region are anti-correlated. A comparison of the similarities in the spectroscopic structure near the footpoints of the arcade loops and more isolated loops suggests the notion of consistent structuring for the bright loops forming an apparent edge of an active region core.

  18. Conservation law for linked cosmic string loops

    NASA Astrophysics Data System (ADS)

    Bekenstein, Jacob D.

    1992-05-01

    Taking a cue from the connection between fluid helicity and the linkage between closed vortices in ordinary turbulent flow, we examine topological restrictions on the linkage of cosmic string loops (or superfluid quantum vortex rings). The analog of helicity in these cases vanishes, but loops (and vortex rings) can link together, the extent of linkage (knotting included) being related to the contorsion of the loops or rings by a topological conservation law. This law is respected by intercommunication. One consequence is that total loop contorsion is quantized in integers.

  19. Unified framework for systematic loop transformations

    SciTech Connect

    Lu, L.C.; Chen, M.

    1990-10-01

    This paper presents a formal mathematical framework which unifies the existing loop transformations. This framework also includes more general classes of loop transformations, which can extract more parallelism from a class of programs than the existing techniques. We classify schedules into three classes: uniform, subdomain-variant, and statement-variant. Viewing from the degree of parallelism to be gained by loop transformation, the schedules can also be classified as single-sequential level, multiple-sequential level, and mixed schedules. We also illustrate the usefulness of the more general loop transformation with an example program.

  20. Rural Area Revitalization Act of 1987; and the Rural Development Reorganization Act of 1987. Hearing on H.R. 1800 and H.R. 2026 before the Subcommittee on Conservation, Credit, and Rural Development of the Committee on Agriculture. House of Representatives, One Hundredth Congress, First Session.

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. House Committee on Agriculture.

    Testimony of H.R. 1800, the Rural Area Revitalization Act, and H.R. 2026, the Rural Development Reorganization Act focuses on the need for federal attention to rural problems other than agriculture. The Rural Area Revitalization Act authorizes expansion of capital available for lending in rural areas, a grant program of $25 million per year for…

  1. Closed-Loop Neuroscience and Non-Invasive Brain Stimulation: A Tale of Two Loops

    PubMed Central

    Zrenner, Christoph; Belardinelli, Paolo; Müller-Dahlhaus, Florian; Ziemann, Ulf

    2016-01-01

    Closed-loop neuroscience is receiving increasing attention with recent technological advances that enable complex feedback loops to be implemented with millisecond resolution on commodity hardware. We summarize emerging conceptual and methodological frameworks that are available to experimenters investigating a “brain in the loop” using non-invasive brain stimulation and briefly review the experimental and therapeutic implications. We take the view that closed-loop neuroscience in fact deals with two conceptually quite different loops: a “brain-state dynamics” loop, used to couple with and modulate the trajectory of neuronal activity patterns, and a “task dynamics” loop, that is the bidirectional motor-sensory interaction between brain and (simulated) environment, and which enables goal-directed behavioral tasks to be incorporated. Both loops need to be considered and combined to realize the full experimental and therapeutic potential of closed-loop neuroscience. PMID:27092055

  2. Chemical Looping Combustion Reactions and Systems

    SciTech Connect

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

    2014-03-01

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

  3. Closing the loop with blur

    NASA Astrophysics Data System (ADS)

    Tani, Jacopo

    A great variety of systems use image sensors to provide measurements for closed loop operation. A drawback of using image sensors in real-time feedback is that they provide measurements at slower sampling rates as compared to the actuators, typically around 30 Hz for CCD cameras, hence acting as the bottleneck for closed loop control bandwidths. While high speed cameras exist, higher frame rates imply an upper bound on exposures which lowers the signal-to-noise-ratio (SNR), reducing measurements accuracy. The integrative nature of image sensors though offers the opportunity to prolong the exposure window and collect motion blurred measurements. This research describes how to exploit the dynamic information of observed system outputs, encoded in motion blur, to control fast systems at the fast rate through slow rate image sensors. In order to achieve this objective it is necessary to (a) design a controller providing fast rate input to the system based on the slow image measurements. Ideally such a controller would require a fast rate estimate of the system's state variables in order to provide the necessary control action, therefore an (b) image blur based estimator is to be developed. State estimators typically need a model of the system in order to provide their estimates, so (c) a system identification problem has to be addressed, where a reliable model describing the frequency content of the system, up to frequencies corresponding to the fast rate, has to be determined through slow rate image sensor measurements. Alternatively when such a procedure is not possible for lack, e.g., of knowledge of the input to the system, then (d) a method to reconstruct the output signal frequency content up to frequencies above those set by the limitations of the sampling theorem is to be devised. Therefore in order to "close the loop with blur", this work describes how to pose and solve the problems of, namely: system identification , state estimation, closed loop control and

  4. Delay locked loop integrated circuit.

    SciTech Connect

    Brocato, Robert Wesley

    2007-10-01

    This report gives a description of the development of a Delay Locked Loop (DLL) integrated circuit (IC). The DLL was developed and tested as a stand-alone IC test chip to be integrated into a larger application specific integrated circuit (ASIC), the Quadrature Digital Waveform Synthesizer (QDWS). The purpose of the DLL is to provide a digitally programmable delay to enable synchronization between an internal system clock and external peripherals with unknown clock skew. The DLL was designed and fabricated in the IBM 8RF process, a 0.13 {micro}m CMOS process. It was designed to operate with a 300MHz clock and has been tested up to 500MHz.

  5. DNA looping mediates nucleosome transfer

    PubMed Central

    Brennan, Lucy D.; Forties, Robert A.; Patel, Smita S.; Wang, Michelle D.

    2016-01-01

    Proper cell function requires preservation of the spatial organization of chromatin modifications. Maintenance of this epigenetic landscape necessitates the transfer of parental nucleosomes to newly replicated DNA, a process that is stringently regulated and intrinsically linked to replication fork dynamics. This creates a formidable setting from which to isolate the central mechanism of transfer. Here we utilized a minimal experimental system to track the fate of a single nucleosome following its displacement, and examined whether DNA mechanics itself, in the absence of any chaperones or assembly factors, may serve as a platform for the transfer process. We found that the nucleosome is passively transferred to available dsDNA as predicted by a simple physical model of DNA loop formation. These results demonstrate a fundamental role for DNA mechanics in mediating nucleosome transfer and preserving epigenetic integrity during replication. PMID:27808093

  6. Closed loop steam cooled airfoil

    DOEpatents

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

    2006-04-18

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

  7. UWB communication receiver feedback loop

    DOEpatents

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

    2007-12-04

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

  8. R-loopDB: a database for R-loop forming sequences (RLFS) and R-loops

    PubMed Central

    Jenjaroenpun, Piroon; Wongsurawat, Thidathip; Sutheeworapong, Sawannee; Kuznetsov, Vladimir A.

    2017-01-01

    R-loopDB (http://rloop.bii.a-star.edu.sg) was originally constructed as a collection of computationally predicted R-loop forming sequences (RLFSs) in the human genic regions. The renewed R-loopDB provides updates, improvements and new options, including access to recent experimental data. It includes genome-scale prediction of RLFSs for humans, six other animals and yeast. Using the extended quantitative model of RLFSs (QmRLFS), we significantly increased the number of RLFSs predicted in the human genes and identified RLFSs in other organism genomes. R-loopDB allows searching of RLFSs in the genes and in the 2 kb upstream and downstream flanking sequences of any gene. R-loopDB exploits the Ensembl gene annotation system, providing users with chromosome coordinates, sequences, gene and genomic data of the 1 565 795 RLFSs distributed in 121 056 genic or proximal gene regions of the covered organisms. It provides a comprehensive annotation of Ensembl RLFS-positive genes including 93 454 protein coding genes, 12 480 long non-coding RNA and 7 568 small non-coding RNA genes and 7 554 pseudogenes. Using new interface and genome viewers of R-loopDB, users can search the gene(s) in multiple species with keywords in a single query. R-loopDB provides tools to carry out comparative evolution and genome-scale analyses in R-loop biology. PMID:27899586

  9. Potential Cost Savings for Use of 3D Printing Combined With 3D Imaging and CPLM for Fleet Maintenance and Revitalization

    DTIC Science & Technology

    2013-12-04

    pmlkploba=obmloq=pbofbp= = = Potential Cost Savings for Use of 3D Printing Combined With 3D Imaging and CPLM for Fleet Maintenance and Revitalization...REPORT TYPE 3. DATES COVERED 00-00-2013 to 00-00-2013 4. TITLE AND SUBTITLE Potential Cost Savings for Use of 3D Printing Combined With 3D ...oÉëÉ~êÅÜ=mêçÖê~ã= ëéçåëçêÉÇ=oÉéçêí=pÉêáÉë= Potential Cost Savings for Use of 3D Printing Combined With 3D Imaging and CPLM for Fleet Maintenance and

  10. Chemical Looping Combustion System-Fuel Reactor Modeling

    SciTech Connect

    Gamwo, I.K.; Jung, J.; Anderson, R.R.; Soong, Y.

    2007-04-01

    Chemical looping combustion (CLC) is a process in which an oxygen carrier is used for fuel combustion instead of air or pure oxygen as shown in the figure below. The combustion is split into air and fuel reactors where the oxidation of the oxygen carrier and the reduction of the oxidized metal occur respectively. The CLC system provides a sequestration-ready CO2 stream with no additional energy required for separation. This major advantage places combustion looping at the leading edge of a possible shift in strict control of CO2 emissions from power plants. Research in this novel technology has been focused in three distinct areas: techno-economic evaluations, integration of the system into power plant concepts, and experimental development of oxygen carrier metals such as Fe, Ni, Mn, Cu, and Ca. Our recent thorough literature review shows that multiphase fluid dynamics modeling for CLC is not available in the open literature. Here, we have modified the MFIX code to model fluid dynamic in the fuel reactor. A computer generated movie of our simulation shows bubble behavior consistent with experimental observations.

  11. Three-loop cusp anomalous dimension and a conjecture for n loops

    NASA Astrophysics Data System (ADS)

    Kidonakis, Nikolaos

    2016-05-01

    I present analytical expressions for the massive cusp anomalous dimension in QCD through three loops, first calculated in 2014, in terms of elementary functions and ordinary polylogarithms. I observe interesting relations between the results at different loops and provide a conjecture for the n-loop cusp anomalous dimension in terms of the lower-loop results. I also present numerical results and simple approximate formulas for the cusp anomalous dimension relevant to top-quark production.

  12. Gravitational steady states of solar coronal loops

    NASA Astrophysics Data System (ADS)

    Sugiyama, Linda E.; Asgari-Targhi, M.

    2017-02-01

    Coronal loops on the surface of the sun appear to consist of curved, plasma-confining magnetic flux tubes or "ropes," anchored at both ends in the photosphere. Toroidal loops carrying current are inherently unstable to expansion in the major radius due to toroidal-curvature-induced imbalances in the magnetic and plasma pressures. An ideal MHD analysis of a simple isolated loop with density and pressure higher than the surrounding corona, based on the theory of magnetically confined toroidal plasmas, shows that the radial force balance depends on the loop internal structure and varies over parameter space. It provides a unified picture of simple loop steady states in terms of the plasma beta βo, the inverse aspect ratio ɛ =a /Ro , and the MHD gravitational parameter G ̂≡g a /vA2 , all at the top of the loop, where g is the acceleration due to gravity, a the average minor radius, and vA the shear Alfvén velocity. In the high and low beta tokamak orderings, βo=2 noT /(Bo2/2 μo)˜ɛ1 and ɛ2 , that fit many loops, the solar gravity can sustain nonaxisymmetric steady states at G ̂˜ɛ βo that represent the maximum stable height. At smaller G ̂≤ɛ2βo , the loop is axisymmetric to leading order and stabilized primarily by the two fixed loop ends. Very low beta, nearly force-free, steady states with βo˜ɛ3 may also exist, with or without gravity, depending on higher order effects. The thin coronal loops commonly observed in solar active regions have ɛ ≃0.02 and fit the high beta steady states. G ̂ increases with loop height. Fatter loops in active regions that form along magnetic neutral lines and may lead to solar flares and Coronal Mass Ejections have ɛ ≃0.1 -0.2 and may fit the low beta ordering. Larger loops tend to have G ̂>ɛ βo and be unstable to radial expansion because the exponential hydrostatic reduction in the density at the loop-top reduces the gravitational force -ρG ̂ R ̂ below the level that balances expansion, in agreement with

  13. Dihedral-like constructions of automorphic loops

    NASA Astrophysics Data System (ADS)

    Aboras, Mouna

    In this dissertation we study dihedral-like constructions of automorphic loops. Automorphic loops are loops in which all inner mappings are automorphisms. We start by describing a generalization of the dihedral construction for groups. Namely, if (G, +) is an abelian group, m > 1 and alpha ∈2 Aut(G), let Dih(m, G, alpha) on Zm x G be defined by. (i, u)(j, v) = (i + j, ((--1)ju + v)alpha ij). We prove that the resulting loop is automorphic if and only if m = 2 or (alpha2 = 1 and m is even) or (m is odd, alpha = 1 and exp(G) ≤ 2). In the last case, the loop is a group. The case m = 2 was introduced by Kinyon, Kunen, Phillips, and Vojtechovsky. We study basic structural properties of dihedral-like automorphic loops. We describe certain subloops, including: nucleus, commutant, center, associator subloop and derived subloop. We prove theorems for dihedral-like automorphic loops analogous to the Cauchy and Lagrange theorems for groups, and further we discuss the coset decomposition in dihedral-like automorphic loops. We show that two finite dihedral-like automorphic loops Dih( m, G, alpha) and Dih(m¯, G¯, [special character omitted]) are isomorphic if and only if m = m¯, G ≅ G¯ and alpha is conjugate to [special character omitted] in Aut(G). We describe the automorphism group of Q and its subgroup consisting of inner mappings of Q. Finally, due to the solution to the isomorphism problem, we are interested in studying conjugacy classes of automorphism groups of finite abelian groups. Then we describe all dihedral-like automorphic loops of order < 128 up to isomorphism. We conclude with a description of all dihedral-like automorphic loops of order < 64 up to isotopism.

  14. Glycoprotein Degradation in the Blind Loop Syndrome

    PubMed Central

    Prizont, Roberto

    1981-01-01

    Contents obtained from jejunum of normal controls, self-emptying and self-filling blind loop rats were analyzed for the presence of glycoprotein-degrading glycosidases. The blind loop syndrome was documented by the increased fat excretion and slower growth rate of self-filling blind loop rats 6 wk after surgery. With p-nitrophenylglycosides as substrate, the specific activity of α-N-acetylgalactosaminidase, a potential blood group A destroying glycosidase, was 0.90±0.40 mU/mg of protein. This level was 23-fold higher than the specific activity of normal controls. In partially purified self-filling blind loop contents, the activity of α-N-acetylgalactosaminidase was 9- to 70-fold higher than activities of self-emptying and normal controls. Antibiotic treatment with chloromycetin and polymyxin decreased 24-fold the glycosidase levels in self-filling blind loops. In experiments with natural substrate, the blood group A titer of a20,000g supernate from normal jejunal homogenates decreased 128-fold after 24-h incubation with blind loop contents. Normal contents failed to diminish the blood group reactivity of the natural substrate. Furthermore, blind loop contents markedly decreased the blood group A titer of isolated brush borders. Incubation between blind loop bacteria and mucosal homogenates or isolated brush borders labeled with d-[U-14C]glucosamine revealed increased production of labeled ether extractable organic acids. Likewise, intraperitoneal injection of d-[U-14C]glucosamine into self-filling blind loop rats resulted in incorporation of the label into luminal short chain fatty acids. These results suggest that glycosidases may provide a mechanism by which blind loop bacteria obtain sugars from intestinal glycoproteins. The released sugars are used and converted by bacteria into energy and organic acids. This use of the host's glycoproteins would allow blind loop bacteria to grow and survive within the lumen independent of exogenous sources. PMID:6257760

  15. The Cygnus Loop: An Older Supernova Remnant.

    ERIC Educational Resources Information Center

    Straka, William

    1987-01-01

    Describes the Cygnus Loop, one of brightest and most easily studied of the older "remnant nebulae" of supernova outbursts. Discusses some of the historical events surrounding the discovery and measurement of the Cygnus Loop and makes some projections on its future. (TW)

  16. Formation of Chromosomal Domains by Loop Extrusion.

    PubMed

    Fudenberg, Geoffrey; Imakaev, Maxim; Lu, Carolyn; Goloborodko, Anton; Abdennur, Nezar; Mirny, Leonid A

    2016-05-31

    Topologically associating domains (TADs) are fundamental structural and functional building blocks of human interphase chromosomes, yet the mechanisms of TAD formation remain unclear. Here, we propose that loop extrusion underlies TAD formation. In this process, cis-acting loop-extruding factors, likely cohesins, form progressively larger loops but stall at TAD boundaries due to interactions with boundary proteins, including CTCF. Using polymer simulations, we show that this model produces TADs and finer-scale features of Hi-C data. Each TAD emerges from multiple loops dynamically formed through extrusion, contrary to typical illustrations of single static loops. Loop extrusion both explains diverse experimental observations-including the preferential orientation of CTCF motifs, enrichments of architectural proteins at TAD boundaries, and boundary deletion experiments-and makes specific predictions for the depletion of CTCF versus cohesin. Finally, loop extrusion has potentially far-ranging consequences for processes such as enhancer-promoter interactions, orientation-specific chromosomal looping, and compaction of mitotic chromosomes.

  17. External Tank CIL Closed Loop Verification System

    NASA Technical Reports Server (NTRS)

    Hartley, Eugene A., Jr.

    2005-01-01

    Lockheed Martin was requested to develop a closed loop CIL system following the Challenger accident. The system that was developed has proven to be very robust with minimal problems since implementation, having zero escapes in the last 7 years (27 External Tanks). We are currently investigating expansion of the CIL Closed Loop system to include "MI" CILs.

  18. Loop calculus for lattice gauge theories

    SciTech Connect

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

    1989-05-15

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

  19. On Novice Loop Boundaries and Range Conceptions

    ERIC Educational Resources Information Center

    Ginat, David

    2004-01-01

    The paper presents a study of novice difficulties with range conceptions in loop design. CS2 students were asked to solve four related enumeration tasks, which required various loop boundary specifications. The student solutions varied considerably in conciseness and efficiency. The solution diversity reveals significant differences in range…

  20. Vacuum Energy Sequestering and Graviton Loops.

    PubMed

    Kaloper, Nemanja; Padilla, Antonio

    2017-02-10

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

  1. Complete renormalization of QCD at five loops

    NASA Astrophysics Data System (ADS)

    Luthe, Thomas; Maier, Andreas; Marquard, Peter; Schröder, York

    2017-03-01

    We present new analytical five-loop Feynman-gauge results for the anomalous dimensions of ghost field and -vertex, generalizing the known values for SU(3) to a general gauge group. Together with previously published results on the quark mass and -field anomalous dimensions and the Beta function, this completes the 5-loop renormalization program of gauge theories in that gauge.

  2. Vacuum Energy Sequestering and Graviton Loops

    NASA Astrophysics Data System (ADS)

    Kaloper, Nemanja; Padilla, Antonio

    2017-02-01

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

  3. Spring control of wire harness loops

    NASA Technical Reports Server (NTRS)

    Curcio, P. J.

    1979-01-01

    Negator spring control guides wire harness between movable and fixed structure. It prevents electrical wire harness loop from jamming or being severed as wire moves in response to changes in position of aircraft rudder. Spring-loaded coiled cable controls wire loop regardless of rudder movement.

  4. Decision Aids for Naval Air ASW

    DTIC Science & Technology

    1980-03-15

    referred to as the target’s Location, with a capital "L.") The following description will describe a single iteration through the loop. 4.4.2 Underlying...Crawford M. L. Metersky American Psycological Association Naval Air Development Center Office of Educational Affairs Code 2031 1200 17th Street, NW

  5. Acquisition performance of various QPSK carrier tracking loops

    NASA Technical Reports Server (NTRS)

    Hinedi, S.; Shah, B.

    1992-01-01

    The frequency and phase acquisition performance of three quadrature phase shift keying (QPSK) carrier tracking loops, the MAP estimation loop, the Costas crossover loop, and the generalized Costas loop, is described. Acquisition time and probability of acquisition as a function of both loop signal-to-noise ratio and frequency offset to loop bandwidth ratio are obtained via computer simulations for type II and III loops. It is shown that the MAP loop, which results in the smallest squaring loss for all signal-to-noise ratios, is sometimes outperformed by the other two loops in terms of acquisition time and acquisition probability.

  6. REVIEWS OF TOPICAL PROBLEMS: Coronal magnetic loops

    NASA Astrophysics Data System (ADS)

    Zaitsev, Valerii V.; Stepanov, Alexander V.

    2008-11-01

    The goal of this review is to outline some new ideas in the physics of coronal magnetic loops, the fundamental structural elements of the atmospheres of the Sun and flaring stars, which are involved in phenomena such as stellar coronal heating, flare energy release, charged particle acceleration, and the modulation of optical, radio, and X-ray emissions. The Alfvén-Carlqvist view of a coronal loop as an equivalent electric circuit allows a good physical understanding of loop processes. Describing coronal loops as MHD-resonators explains various ways in which flaring emissions from the Sun and stars are modulated, whereas modeling them by magnetic mirror traps allows one to describe the dynamics and emission of high-energy particles. Based on these approaches, loop plasma and fast particle parameters are obtained and models for flare energy release and stellar corona heating are developed.

  7. Damped transverse oscillations of interacting coronal loops

    NASA Astrophysics Data System (ADS)

    Soler, Roberto; Luna, Manuel

    2015-10-01

    Damped transverse oscillations of magnetic loops are routinely observed in the solar corona. This phenomenon is interpreted as standing kink magnetohydrodynamic waves, which are damped by resonant absorption owing to plasma inhomogeneity across the magnetic field. The periods and damping times of these oscillations can be used to probe the physical conditions of the coronal medium. Some observations suggest that interaction between neighboring oscillating loops in an active region may be important and can modify the properties of the oscillations. Here we theoretically investigate resonantly damped transverse oscillations of interacting nonuniform coronal loops. We provide a semi-analytic method, based on the T-matrix theory of scattering, to compute the frequencies and damping rates of collective oscillations of an arbitrary configuration of parallel cylindrical loops. The effect of resonant damping is included in the T-matrix scheme in the thin boundary approximation. Analytic and numerical results in the specific case of two interacting loops are given as an application.

  8. A communication scheme for the distrubted execution of loop nests with while loops

    SciTech Connect

    Griebl, M.; Lengauer, C.

    1995-10-01

    The mathematical model for the parallelization, or {open_quotes}space-time mapping,{close_quotes} of loop nests is the polyhedron model. The presence of while loops in the nest complicates matters for two reasons: (1) the parallelized loop nest does not correspond to a polyhedron but instead to a subset that resembles a (multi-dimensional) comb and (2) it is not clear when the entire loop nest has terminated. We describe a communication scheme which can deal with both problems and which can be added to the parallel target loop nest by a compiler.

  9. Floating Refrigerant Loop Based on R-134a Refrigerant Cooling of High-Heat Flux Electronics

    SciTech Connect

    Lowe, K.T.

    2005-10-07

    The Oak Ridge National Laboratory (ORNL) Power Electronics and Electric Machinery Research Center (PEEMRC) have been developing technologies to address the thermal issues associated with hybrid vehicles. Removal of the heat generated from electrical losses in traction motors and their associated power electronics is essential for the reliable operation of motors and power electronics. As part of a larger thermal control project, which includes shrinking inverter size and direct cooling of electronics, ORNL has developed U.S. Patent No. 6,772,603 B2, ''Methods and Apparatus for Thermal Management of Vehicle Systems and Components'' [1], and patent pending, ''Floating Loop System for Cooling Integrated Motors and Inverters Using Hot Liquid Refrigerant'' [2]. The floating-loop system provides a large coefficient of performance (COP) for hybrid-drive component cooling. This loop (based on R-134a) is integrated with a vehicle's existing air-conditioning (AC) condenser, which dissipates waste heat to the ambient air. Because the temperature requirements for cooling of power electronics and electric machines are not as low as that required for passenger compartment air, this adjoining loop can operate on the high-pressure side of the existing AC system. This arrangement also allows the floating loop to run without the need for the compressor and only needs a small pump to move the liquid refrigerant. For the design to be viable, the loop must not adversely affect the existing system. The loop should also provide a high COP, a flat-temperature profile, and low-pressure drop. To date, the floating-loop test prototype has successfully removed 2 kW of heat load in a 9 kW automobile passenger AC system with and without the automotive AC system running. The COP for the tested floating-loop system ranges from 40-45, as compared to a typical AC system COP of about 2-4. The estimated required waste-heat load for future hybrid applications is 5.5 kW and the existing system could be

  10. Fiber loop ringdown strain sensor with photonic crystal fiber based Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Zhou, Wenjun; Wong, Wei Chang; Chan, Chi Chiu; Shao, Li-Yang; Dong, Xinyong

    2011-05-01

    A highly sensitive strain sensor is demonstrated by inserting a photonic crystal fiber (PCF) based Mach-Zehnder interferometer (MZI) in a cavity ringdown fiber loop as the lossy sensing element. The MZI consists of a piece of PCF spliced to single-mode fibers, in which the PCF air holes are collapsed over a short region at two splicing points for coupling the core and cladding modes. By measuring the decay constants of the fiber ringdown loop, a high strain sensitivity of ~0.21 μs-1/mɛ and a minimum detectable strain of ~3.6 μɛ were obtained.

  11. Air Pollution.

    ERIC Educational Resources Information Center

    Gilpin, Alan

    A summary of one of our most pressing environmental problems, air pollution, is offered in this book by the Director of Air Pollution Control for the Queensland (Australia) State Government. Discussion of the subject is not restricted to Queensland or Australian problems and policies, however, but includes analysis of air pollution the world over.…

  12. Air Pollution

    MedlinePlus

    ... of Climate Change on Children's Health: Session Two: Air Quality Impacts MODERATOR: Susan Anenberg, EPA Meredith McCormack, Johns ... University • Effects of Climate Change on Children’s Health: Air Quality Impacts Frederica Perera, Columbia University • Air quality Impacts ...

  13. Cygnus Loop Supernova Blast Wave

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This is an image of a small portion of the Cygnus Loop supernova remnant, which marks the edge of a bubble-like, expanding blast wave from a colossal stellar explosion, occurring about 15,000 years ago. The HST image shows the structure behind the shock waves, allowing astronomers for the first time to directly compare the actual structure of the shock with theoretical model calculations. Besides supernova remnants, these shock models are important in understanding a wide range of astrophysical phenomena, from winds in newly-formed stars to cataclysmic stellar outbursts. The supernova blast is slamming into tenuous clouds of insterstellar gas. This collision heats and compresses the gas, causing it to glow. The shock thus acts as a searchlight revealing the structure of the interstellar medium. The detailed HST image shows the blast wave overrunning dense clumps of gas, which despite HST's high resolution, cannot be resolved. This means that the clumps of gas must be small enough to fit inside our solar system, making them relatively small structures by interstellar standards. A bluish ribbon of light stretching left to right across the picture might be a knot of gas ejected by the supernova; this interstellar 'bullet' traveling over three million miles per hour (5 million kilometres) is just catching up with the shock front, which has slowed down by ploughing into interstellar material. The Cygnus Loop appears as a faint ring of glowing gases about three degrees across (six times the diameter of the full Moon), located in the northern constellation, Cygnus the Swan. The supernova remnant is within the plane of our Milky Way galaxy and is 2,600 light-years away. The photo is a combination of separate images taken in three colors, oxygen atoms (blue) emit light at temperatures of 30,000 to 60,000 degrees Celsius (50,000 to 100,000 degrees Farenheit). Hydrogen atoms (green) arise throughout the region of shocked gas. Sulfur atoms (red) form when the gas cools to

  14. Quantitation of interactions between two DNA loops demonstrates loop domain insulation in E. coli cells

    PubMed Central

    Priest, David G.; Kumar, Sandip; Yan, Yan; Dunlap, David D.; Dodd, Ian B.; Shearwin, Keith E.

    2014-01-01

    Eukaryotic gene regulation involves complex patterns of long-range DNA-looping interactions between enhancers and promoters, but how these specific interactions are achieved is poorly understood. Models that posit other DNA loops—that aid or inhibit enhancer–promoter contact—are difficult to test or quantitate rigorously in eukaryotic cells. Here, we use the well-characterized DNA-looping proteins Lac repressor and phage λ CI to measure interactions between pairs of long DNA loops in E. coli cells in the three possible topological arrangements. We find that side-by-side loops do not affect each other. Nested loops assist each other’s formation consistent with their distance-shortening effect. In contrast, alternating loops, where one looping element is placed within the other DNA loop, inhibit each other’s formation, thus providing clear support for the loop domain model for insulation. Modeling shows that combining loop assistance and loop interference can provide strong specificity in long-range interactions. PMID:25288735

  15. Sequence–structure relationships in RNA loops: establishing the basis for loop homology modeling

    PubMed Central

    Schudoma, Christian; May, Patrick; Nikiforova, Viktoria; Walther, Dirk

    2010-01-01

    The specific function of RNA molecules frequently resides in their seemingly unstructured loop regions. We performed a systematic analysis of RNA loops extracted from experimentally determined three-dimensional structures of RNA molecules. A comprehensive loop-structure data set was created and organized into distinct clusters based on structural and sequence similarity. We detected clear evidence of the hallmark of homology present in the sequence–structure relationships in loops. Loops differing by <25% in sequence identity fold into very similar structures. Thus, our results support the application of homology modeling for RNA loop model building. We established a threshold that may guide the sequence divergence-based selection of template structures for RNA loop homology modeling. Of all possible sequences that are, under the assumption of isosteric relationships, theoretically compatible with actual sequences observed in RNA structures, only a small fraction is contained in the Rfam database of RNA sequences and classes implying that the actual RNA loop space may consist of a limited number of unique loop structures and conserved sequences. The loop-structure data sets are made available via an online database, RLooM. RLooM also offers functionalities for the modeling of RNA loop structures in support of RNA engineering and design efforts. PMID:19923230

  16. Analysis of Free Legal Counselling for the Great East Japan Earthquake and the Outlook for the Field of Disaster Recovery and Revitalization Law

    PubMed Central

    OKAMOTO, Tadashi

    2016-01-01

    Of the free legal counselling conducted by lawyers following the Great East Japan Earthquake, the results of analysis of approx. 40,000 cases have been disclosed by the Japan Federation of Bar Associations. These analysis results have been used as evidence serving as the basis for system revision and new legislation following the disaster, and have been of value to public policy, to a certain extent. In order to identify methods for realizing policy targets as know-how for public policy through the integration and analysis of legal needs in disaster areas, in FY2012 and thereafter, lectures on the “Disaster Recovery and Revitalization Law” were initiated by the Graduate School of Public Policy, Chuo University; Keio University Law School; and other institutions. Under the Disaster Recovery and Revitalization Law, new public policy education fusing various fields of government, policy, law, disaster prevention and crisis management, etc. has been implemented. By utilizing the database on free legal counselling, it may be possible to identify legal systems that need to be ironed out or problems related to public policy in preparation for a huge disaster such as an earthquake directly striking the Tokyo metropolitan area or an earthquake in the Nankai Trough. It is thought that intensifying study of relevant fields will result in the proposal of new designs in the fields of disaster prevention and crisis management. PMID:28299243

  17. Combustor air flow control method for fuel cell apparatus

    DOEpatents

    Clingerman, Bruce J.; Mowery, Kenneth D.; Ripley, Eugene V.

    2001-01-01

    A method for controlling the heat output of a combustor in a fuel cell apparatus to a fuel processor where the combustor has dual air inlet streams including atmospheric air and fuel cell cathode effluent containing oxygen depleted air. In all operating modes, an enthalpy balance is provided by regulating the quantity of the air flow stream to the combustor to support fuel cell processor heat requirements. A control provides a quick fast forward change in an air valve orifice cross section in response to a calculated predetermined air flow, the molar constituents of the air stream to the combustor, the pressure drop across the air valve, and a look up table of the orifice cross sectional area and valve steps. A feedback loop fine tunes any error between the measured air flow to the combustor and the predetermined air flow.

  18. Chemical Looping Reforming for H2, CO and Syngas Production

    SciTech Connect

    Bhavsar,Saurabh; Najera,Michelle; Solunke,Rahul; Veser,Götz

    2001-06-06

    We demonstrate that the extension of CLC onto oxidants beyond air opens new, highly efficient pathways for production of ultra-pure hydrogen, activation of CO{sub 2} via reduction to CO, and are currently working on production of syngas using nanocomposite Fe-BHA. CLR hold great potential due to fuel flexibility and CO{sub 2} capture. Chemical Looping Combustion (CLC) is a novel clean combustion technology which offers an elegant and highly efficient route for fossil fuel combustion. In CLC, combustion of a fuel is broken down into two spatially separated steps. In the reducer, the oxygen carrier (typically a metal) supplies the stoichiometric oxygen required for fuel combustion. In the oxidizer, the oxygen-depleted carrier is then re-oxidized with air. After condensation of steam from the effluent of the reducer, a high-pressure, high-purity sequestration-ready CO{sub 2} stream is obtained. In the present study, we apply the CLC principle to the production of high-purity H{sub 2}, CO, and syngas streams by replacing air with steam and/or CO{sub 2} as oxidant, respectively. Using H{sub 2}O as oxidant, pure hydrogen streams can be obtained. Similarly, using CO{sub 2} as oxidant, CO is obtained, thus opening an efficient route for CO{sub 2} utilization. Using steam and CO{sub 2} mixtures for carrier oxidation should thus allow production of syngas with adjustable CO:H{sub 2} ratios. Overall, these processes result in Chemical Looping Reforming (CLR), i.e. the net overall reaction is the steam and/or dry reforming of the respective fuel.

  19. Looping charged elastic rods: applications to protein-induced DNA loop formation.

    PubMed

    Cherstvy, A G

    2011-01-01

    We analyze looping of thin charged elastic filaments under applied torques and end forces, using the solution of linear elasticity theory equations. In application to DNA, we account for its polyelectrolyte character and charge renormalization, calculating electrostatic energies stored in the loops. We argue that the standard theory of electrostatic persistence is only valid when the loop's radius of curvature and close-contact distance are much larger than the Debye screening length. We predict that larger twist rates are required to trigger looping of charged rods as compared with neutral ones. We then analyze loop shapes formed on charged filaments of finite length, mimicking DNA looping by proteins with two DNA-binding domains. We find optimal loop shapes at different salt amounts, minimizing the sum of DNA elastic, DNA electrostatic, and protein elastic energies. We implement a simple model where intercharge repulsions do not affect the loop shape directly but can choose the energy-optimized shape from the allowed loop types. At low salt concentrations more open loops are favored due to enhanced repulsion of DNA charges, consistent with the results of computer simulations on formation of DNA loops by lac repressor. Then, we model the precise geometry of DNA binding by the lac tetramer and explore loop shapes, varying the confined DNA length and protein opening angle. The characteristics of complexes obtained, such as the total loop energy, stretching forces required to maintain its shape, and the reduction of electrostatic energy with increment of salt, are in good agreement with the outcomes of more elaborate numerical calculations for lac-repressor-induced DNA looping.

  20. Integration of calcium and chemical looping combustion using composite CaO/CuO-based materials.

    PubMed

    Manovic, Vasilije; Anthony, Edward J

    2011-12-15

    Calcium looping cycles (CaL) and chemical looping combustion (CLC) are two new, developing technologies for reduction of CO(2) emissions from plants using fossil fuels for energy production, which are being intensively examined. Calcium looping is a two-stage process, which includes oxy-fuel combustion for sorbent regeneration, i.e., generation of a concentrated CO(2) stream. This paper discuss the development of composite materials which can use copper(II)-oxide (CuO) as an oxygen carrier to provide oxygen for the sorbent regeneration stage of calcium looping. In other words, the work presented here involves integration of calcium looping and chemical looping into a new class of postcombustion CO(2) capture processes designated as integrated CaL and CLC (CaL-CLC or Ca-Cu looping cycles) using composite pellets containing lime (CaO) and CuO together with the addition of calcium aluminate cement as a binder. Their activity was tested in a thermogravimetric analyzer (TGA) during calcination/reduction/oxidation/carbonation cycles. The calcination/reduction typically was performed in methane (CH(4)), and the oxidation/carbonation stage was carried out using a gas mixture containing both CO(2) and O(2). It was confirmed that the material synthesized is suitable for the proposed cycles; with the very favorable finding that reduction/oxidation of the oxygen carrier is complete. Various schemes for the Ca-Cu looping process have been explored here that would be compatible with these new composite materials, along with some different possibilities for flow directions among carbonator, calciner, and air reactor.

  1. MO-C-BRB-00: President’s Symposium: Revitalizing Scientific Excellence: Turning Research Into Clinical Reality Through Translational Research

    SciTech Connect

    2015-06-15

    between medical physicists, radiologists, oncologists, industry representatives, and other stakeholders. The mission of QIBA is to improve the accuracy and practicality of quantitative image-based biomarkers by increasing precision across devices, patients, and time, an essential step in incorporating quantitative imaging biomarkers into radiology practice. Validated quantitative imaging biomarkers are necessary to support precision medicine initiatives, multimodality / multiparametric applications in medicine, treatment planning and response assessment, and radiogenomics applications. Current applications in the QIBA portfolio extend to cancer diagnosis and treatment, pulmonary diseases, and neurological disorders. The overall goal of this symposium is to illustrate the bidirectional exchange between medical research and clinical practice. Revitalizing scientific excellence in clinical medical physics challenges practitioners to identify clinical limitations, which then drive research innovation; research funded by the NIH and other agencies develops technological solutions to these limitations, which are translated to the care environment to ultimately improve clinical practice in radiology and radiation oncology.

  2. Simulation methods for looping transitions.

    PubMed

    Gaffney, B J; Silverstone, H J

    1998-09-01

    Looping transitions occur in field-swept electron magnetic resonance spectra near avoided crossings and involve a single pair of energy levels that are in resonance at two magnetic field strengths, before and after the avoided crossing. When the distance between the two resonances approaches a linewidth, the usual simulation of the spectra, which results from a linear approximation of the dependence of the transition frequency on magnetic field, breaks down. A cubic approximation to the transition frequency, which can be obtained from the two resonance fields and the field-derivatives of the transition frequencies, along with linear (or better) interpolation of the transition-probability factor, restores accurate simulation. The difference is crucial for accurate line shapes at fixed angles, as in an oriented single crystal, but the difference turns out to be a smaller change in relative intensity for a powder spectrum. Spin-3/2 Cr3+ in ruby and spin-5/2 Fe3+ in transferrin oxalate are treated as examples.

  3. Closed-loop neurostimulation: the clinical experience.

    PubMed

    Sun, Felice T; Morrell, Martha J

    2014-07-01

    Neurostimulation is now an established therapy for the treatment of movement disorders, pain, and epilepsy. While most neurostimulation systems available today provide stimulation in an open-loop manner (i.e., therapy is delivered according to preprogrammed settings and is unaffected by changes in the patient's clinical symptoms or in the underlying disease), closed-loop neurostimulation systems, which modulate or adapt therapy in response to physiological changes, may provide more effective and efficient therapy. At present, few such systems exist owing to the complexities of designing and implementing implantable closed-loop systems. This review focuses on the clinical experience of four implantable closed-loop neurostimulation systems: positional-adaptive spinal cord stimulation for treatment of pain, responsive cortical stimulation for treatment of epilepsy, closed-loop vagus nerve stimulation for treatment of epilepsy, and concurrent sensing and stimulation for treatment of Parkinson disease. The history that led to the development of the closed-loop systems, the sensing, detection, and stimulation technology that closes the loop, and the clinical experiences are presented.

  4. Mitotic chromosome compaction via active loop extrusion

    NASA Astrophysics Data System (ADS)

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

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

  5. Bootstrapping an NMHV amplitude through three loops

    NASA Astrophysics Data System (ADS)

    Dixon, Lance J.; von Hippel, Matt

    2014-10-01

    We extend the hexagon function bootstrap to the next-to-maximally-helicity-violating (NMHV) configuration for six-point scattering in planar = 4 super-Yang-Mills theory at three loops. Constraints from the differential equation, from the operator product expansion (OPE) for Wilson loops with operator insertions, and from multi-Regge factorization, lead to a unique answer for the three-loop ratio function. The three-loop result also predicts additional terms in the OPE expansion, as well as the behavior of NMHV amplitudes in the multi-Regge limit at one higher logarithmic accuracy (NNLL) than was used as input. Both predictions are in agreement with recent results from the flux-tube approach. We also study the multi-particle factorization of multi-loop amplitudes for the first time. We find that the function controlling this factorization is purely logarithmic through three loops. We show that a function U , which is closely related to the parity-even part of the ratio function V , is remarkably simple; only five of the nine possible final entries in its symbol are non-vanishing. We study the analytic and numerical behavior of both the parity-even and parity-odd parts of the ratio function on simple lines traversing the space of cross ratios ( u, v, w), as well as on a few two-dimensional planes. Finally, we present an empirical formula for V in terms of elements of the coproduct of the six-gluon MHV remainder function R 6 at one higher loop, which works through three loops for V (four loops for R 6).

  6. Chemical Looping Autothermal Reforming at a 120 kW Pilot Rig

    NASA Astrophysics Data System (ADS)

    Bofhàr-Nordenkampf, Johannes; Pröll, Tobias; Kolbitsch, Philipp; Hofbauer, Hermann

    Chemical looping with selective oxygen transport allows two step combustion or autothermal reforming without mixing of fuel and air. The reactor system consists of two reactors, an air reactor and a fuel reactor with a suitable oxygen carrier that transports the necessary oxygen for operation. In the present study, a highly active nickel based oxygen carrier is tested in a novel dual circulating fluidized bed (DCFB) system at a scale of 120 kW fuel power. The mean particle size of the oxygen carrier is 120 μm and the pilot rig is fueled with natural gas. For the investigated oxygen carrier high CH4 conversion is achieved. Air/fuel ratio is varied at three different fuel reactor temperatures. For chemical looping reforming one can observe synthesis gas composition close to thermodynamic equilibrium. In spite of the fact that no additional steam has been added to the fuel besides the one present through steam fluidization of the loop seals, coke formation does not occur at global stoichiometric air/fuel ratios above 0.46.

  7. Detecting neutrino magnetic moments with conducting loops

    NASA Astrophysics Data System (ADS)

    Apyan, Aram; Apyan, Armen; Schmitt, Michael

    2008-02-01

    It is well established that neutrinos have mass, yet it is very difficult to measure those masses directly. Within the standard model of particle physics, neutrinos will have an intrinsic magnetic moment proportional to their mass. We examine the possibility of detecting the magnetic moment using a conducting loop. According to Faraday’s law of induction, a magnetic dipole passing through a conducting loop induces an electromotive force in the loop. We compute this electromotive force for neutrinos in several cases, based on a fully covariant formulation of the problem. We discuss prospects for a real experiment, as well as the possibility to test the relativistic formulation of intrinsic magnetic moments.

  8. Loop-quantum-gravity vertex amplitude.

    PubMed

    Engle, Jonathan; Pereira, Roberto; Rovelli, Carlo

    2007-10-19

    Spin foam models are hoped to provide the dynamics of loop-quantum gravity. However, the most popular of these, the Barrett-Crane model, does not have the good boundary state space and there are indications that it fails to yield good low-energy n-point functions. We present an alternative dynamics that can be derived as a quantization of a Regge discretization of Euclidean general relativity, where second class constraints are imposed weakly. Its state space matches the SO(3) loop gravity one and it yields an SO(4)-covariant vertex amplitude for Euclidean loop gravity.

  9. Parallel Digital Phase-Locked Loops

    NASA Technical Reports Server (NTRS)

    Sadr, Ramin; Shah, Biren N.; Hinedi, Sami M.

    1995-01-01

    Wide-band microwave receivers of proposed type include digital phase-locked loops in which band-pass filtering and down-conversion of input signals implemented by banks of multirate digital filters operating in parallel. Called "parallel digital phase-locked loops" to distinguish them from other digital phase-locked loops. Systems conceived as cost-effective solution to problem of filtering signals at high sampling rates needed to accommodate wide input frequency bands. Each of M filters process 1/M of spectrum of signal.

  10. Simulation for close air support

    NASA Astrophysics Data System (ADS)

    Hench, David L.

    2009-05-01

    Close Air Support (CAS) is the use of air power in close proximity to friendly forces against enemy combatants. CAS requires precise and detailed communication between the personnel on the ground and the air vehicles. To be useful, a network simulation should be a superposition on the planning simulations for these activities. In a CAS mission, all of the above activities are critical. A hypothetical CAS mission is modeled as an "as is" solution with stove-piped communications and a "to be" network enabled solution. A co-simulation laboratory using OPNET with SITL (SYSTEM in the Loop, cosim, JFORCES (Joint Force Operational Readiness Combat Effectiveness Simulator), and JSAF (Joint Semi-Automated Forces) simulation system is described.

  11. Power plant VI - Sodium-air

    NASA Astrophysics Data System (ADS)

    Genier, R.

    A sodium-air cycle central receiver solar electric generating plant is described. The system is designed for liquid sodium to be heated to 750 C in the central receiver heat exchangers, pumped down to the tower base to transfer heat to an air loop, then be returned to the receiver aperture. The air loop would heat to 730 C, insufficient for efficient operation of turbines, and would require a further heating by a supplementary burner to temperatures of 950 C. An efficiency of 35.4 percent is projected for a total output of 10,620 kW. The flux is furnished by a field of 743 heliostats with a total surface area of 36,425 sq m, and received by a tower 120 m tall outfitted with a receiver inclined 45 deg from the horizontal. The sodium-air heat exchange is envisioned to take place in a tank of air interpenetrated by continuous, closed, boustrophedonic loops filled with superheated sodium.

  12. Closed loop control of a robot assisted smart flexible needle for percutaneous intervention.

    PubMed

    Maria Joseph, F O; Hutapea, P; Dicker, A; Yu, Y; Podder, T

    2015-08-01

    This paper presents the experimental evaluation of a coordinated control system for a robot and robot-driven shape memory alloy (SMA) actuated smart flexible needle capable of following a curved path for percutaneous intervention. The robot driving the needle is considered the outer loop and the non-linear SMA actuated flexible needle system comprises the inner loop. The two feedback control loops are coordinated in such a way that the robot drives the needle while monitoring the needle's actual deflection against a preplanned ideal trajectory, so that the needle tip reaches the target location within an acceptable accuracy. In air and in water experimental results are presented to validate the ability of the proposed coordinated controller to track the overall desired trajectory which includes the combined trajectory of the robot driver and the needle.

  13. Construction of a Stormwater Detention System And Relocation of 12 Previously Assessed Housing Units, Military Family Housing Revitalization Project, Nellis Air Force Base, Nevada

    DTIC Science & Technology

    2007-02-01

    basis until the first rainy season begins. The Nellis AFB Natural Resources Manager would supervise these activities to ensure that the proposed...scattered with trash piles resulting from decades of illegal household dumping activities as can be seen in photograph 3-1 and 3-2. Due to the...maximum hourly average concentrations above the standard is equal to or less than one. b) Concentrations are expressed first in units in which they

  14. Hierarchical loop detection for mobile outdoor robots

    NASA Astrophysics Data System (ADS)

    Lang, Dagmar; Winkens, Christian; Häselich, Marcel; Paulus, Dietrich

    2012-01-01

    Loop closing is a fundamental part of 3D simultaneous localization and mapping (SLAM) that can greatly enhance the quality of long-term mapping. It is essential for the creation of globally consistent maps. Conceptually, loop closing is divided into detection and optimization. Recent approaches depend on a single sensor to recognize previously visited places in the loop detection stage. In this study, we combine data of multiple sensors such as GPS, vision, and laser range data to enhance detection results in repetitively changing environments that are not sufficiently explained by a single sensor. We present a fast and robust hierarchical loop detection algorithm for outdoor robots to achieve a reliable environment representation even if one or more sensors fail.

  15. A magnetohydrodynamic theory of coronal loop transients

    NASA Technical Reports Server (NTRS)

    Yeh, T.

    1982-01-01

    The physical and geometrical characteristics of solar coronal loop transients are described in an MHD model based on Archimedes' MHD buoyancy force. The theory was developed from interpretation of coronagraphic data, particularly from Skylab. The brightness of a loop is taken to indicate the electron density, and successive pictures reveal the electron enhancement in different columns. The forces which lift the loop off the sun surface are analyzed as an MHD buoyancy force affecting every mass element by imparting an inertial force necessary for heliocentrifugal motion. Thermal forces are responsible for transferring the ambient stress to the interior of the loop to begin the process. The kinematic and hydrostatic buoyancy overcome the gravitational force, and a flux rope can then curve upward, spiralling like a corkscrew with varying cross section around the unwinding solar magnetic field lines.

  16. Mathematical Modeling of Loop Heat Pipes

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  17. Four-loop screened perturbation theory

    NASA Astrophysics Data System (ADS)

    Andersen, Jens O.; Kyllingstad, Lars

    2008-10-01

    We study the thermodynamics of massless ϕ4-theory using screened perturbation theory. In this method, the perturbative expansion is reorganized by adding and subtracting a thermal mass term in the Lagrangian. We calculate the free energy through four loops expanding in a double power expansion in m/T and g2, where m is the thermal mass and g is the coupling constant. The expansion is truncated at order g7 and the loop expansion is shown to have better convergence properties than the weak-coupling expansion. The free energy at order g6 involves the four-loop triangle sum-integral evaluated by Gynther, Laine, Schröder, Torrero, and Vuorinen using the methods developed by Arnold and Zhai. The evaluation of the free energy at order g7 requires the evaluation of a nontrivial three-loop sum-integral, which we calculate by the same methods.

  18. Open-loop digital frequency multiplier

    NASA Technical Reports Server (NTRS)

    Moore, R. C.

    1977-01-01

    Monostable multivibrator is implemented by using digital integrated circuits where multiplier constant is too large for conventional phase-locked-loop integrated circuit. A 400 Hz clock is generated by divide-by-N counter from 1 Hz timing reference.

  19. CHY loop integrands from holomorphic forms

    NASA Astrophysics Data System (ADS)

    Gomez, Humberto; Mizera, Sebastian; Zhang, Guojun

    2017-03-01

    Recently, the Cachazo-He-Yuan (CHY) approach for calculating scattering amplitudes has been extended beyond tree level. In this paper, we introduce a way of constructing CHY integrands for Φ3 theory up to two loops from holomorphic forms on Riemann surfaces. We give simple rules for translating Feynman diagrams into the corresponding CHY integrands. As a complementary result, we extend the Λ-algorithm, originally introduced in arXiv:1604.05373, to two loops. Using this approach, we are able to analytically verify our prescription for the CHY integrands up to seven external particles at two loops. In addition, it gives a natural way of extending to higher-loop orders.

  20. Investigation of gasification chemical looping combustion combined cycle performance

    SciTech Connect

    Wenguo Xiang; Sha Wang; Tengteng Di

    2008-03-15

    A novel combined cycle based on coal gasification and chemical looping combustion (CLC) offers a possibility of both high net power efficiency and separation of the greenhouse gas CO{sub 2}. The technique involves the use of a metal oxide as an oxygen carrier, which transfers oxygen from the combustion air to the fuel, and the avoidance of direct contact between fuel and combustion air. The fuel gas is oxidized by an oxygen carrier, an oxygen-containing compound, in the fuel reactor. The oxygen carrier in this study is NiO. The reduced oxygen carrier, Ni, in the fuel reactor is regenerated by the air in the air reactor. In this way, fuel and air are never mixed, and the fuel oxidation products CO{sub 2} and water vapor leave the system undiluted by air. All that is needed to get an almost pure CO{sub 2} product is to condense the water vapor and to remove the liquid water. When the technique is combined with gas turbine and heat recovery steam generation technology, a new type of combined cycle is formed which gives a possibility of obtaining high net power efficiency and CO{sub 2} separation. The performance of the combined cycle is simulated using the ASPEN software tool in this paper. The influence of the water/coal ratio on the gasification and the influence of the CLC process parameters such as the air reactor temperature, the turbine inlet supplementary firing, and the pressure ratio of the compressor on the system performance are discussed. Results show that, assuming an air reactor temperature of 1200{sup o}C, a gasification temperature of 1100 {sup o}C, and a turbine inlet temperature after supplementary firing of 1350{sup o}C, the system has the potential to achieve a thermal efficiency of 44.4% (low heating value), and the CO{sub 2} emission is 70.1 g/(kW h), 90.1% of the CO{sub 2} captured. 22 refs., 7 figs., 6 tabs.

  1. A multiple-pass ring oscillator based dual-loop phase-locked loop

    NASA Astrophysics Data System (ADS)

    Danfeng, Chen; Junyan, Ren; Jingjing, Deng; Wei, Li; Ning, Li

    2009-10-01

    A dual-loop phase-locked loop (PLL) for wideband operation is proposed. The dual-loop architecture combines a coarse-tuning loop with a fine-tuning one, enabling a wide tuning range and low voltage-controlled oscillator (VCO) gain without poisoning phase noise and reference spur suppression performance. An analysis of the phase noise and reference spur of the dual-loop PLL is emphasized. A novel multiple-pass ring VCO is designed for the dual-loop application. It utilizes both voltage-control and current-control simultaneously in the delay cell. The PLL is fabricated in Jazz 0.18-μm RF CMOS technology. The measured tuning range is from 4.2 to 5.9 GHz. It achieves a low phase noise of -99 dBc/Hz @ 1 MHz offset from a 5.5 GHz carrier.

  2. Air Policing

    DTIC Science & Technology

    2009-05-01

    Iraq. To provide a background for understanding why Britain commenced the policy of air policing, this paper begins with a review of contemporary...7 Omissi, Air Power, XV. 8 policing actions or the pushing home of advantages gained by the air.” Within the context of this paper , the...control operations, and therefore within the context of this paper , the term coercive airpower refers to the threat of harming a population or the threat

  3. Deployable radiator with flexible line loop

    NASA Technical Reports Server (NTRS)

    Keeler, Bryan V. (Inventor); Lehtinen, Arthur Mathias (Inventor); McGee, Billy W. (Inventor)

    2003-01-01

    Radiator assembly (10) for use on a spacecraft (12) is provided including at least one radiator panel assembly (26) repeatably movable between a panel stowed position (28) and a panel deployed position (36), at least two flexible lines (40) in fluid communication with the at least one radiator panel assembly (26) and repeatably movable between a stowage loop (42) and a flattened deployed loop (44).

  4. Miniature loops in the solar corona

    NASA Astrophysics Data System (ADS)

    Barczynski, K.; Peter, H.; Savage, S. L.

    2017-03-01

    Context. Magnetic loops filled with hot plasma are the main building blocks of the solar corona. Usually they have lengths of the order of the barometric scale height in the corona that is 50 Mm. Aims: Previously it has been suggested that miniature versions of hot loops exist. These would have lengths of only 1 Mm barely protruding from the chromosphere and spanning across just one granule in the photosphere. Such short loops are well established at transition region temperatures (0.1 MK), and we investigate if such miniature loops also exist at coronal temperatures (>1 MK). Methods: We used extreme UV (EUV) imaging observations from the High-resolution Coronal Imager (Hi-C) at an unprecedented spatial resolution of 0.3'' to 0.4''. Together with EUV imaging and magnetogram data from the Solar Dynamics Observatory (SDO) and X-Ray Telescope (XRT) data from Hinode we investigated the spatial, temporal and thermal evolution of small loop-like structures in the solar corona above a plage region close to an active region and compared this to a moss area within the active region. Results: We find that the size, motion and temporal evolution of the loop-like features are consistent with photospheric motions, suggesting a close connection to the photospheric magnetic field. Aligned magnetograms show that one of their endpoints is rooted at a magnetic concentration. Their thermal structure, as revealed together with the X-ray observations, shows significant differences to moss-like features. Conclusions: Considering different scenarios, these features are most probably miniature versions of hot loops rooted at magnetic concentrations at opposite sides of a granule in small emerging magnetic loops (or flux tubes).

  5. Simple system for locating ground loops.

    PubMed

    Bellan, P M

    2007-06-01

    A simple low-cost system for rapid identification of the cables causing ground loops in complex instrumentation configurations is described. The system consists of an exciter module that generates a 100 kHz ground loop current and a detector module that determines which cable conducts this test current. Both the exciter and detector are magnetically coupled to the ground circuit so there is no physical contact to the instrumentation system under test.

  6. Can Chemical Looping Combustion Use CFB Technology?

    SciTech Connect

    Gamwo, I.K.

    2006-11-01

    Circulating Fluidized Bed (CFB) technology has demonstrated an unparalleled ability to achieve low SO2 and NOx emissions for coal-fired power plants without CO2 capture. Chemical Looping combustion (CLC) is a novel fuel combustion technology which appears as a leading candidate in terms of competitiveness for CO2 removal from flue gas. This presentaion deals with the adaptation of circulating fluidized bed technology to Chemical looping combustion

  7. Onset of inflation in loop quantum cosmology

    SciTech Connect

    Germani, Cristiano; Nelson, William; Sakellariadou, Mairi

    2007-08-15

    Using a Liouville measure, similar to the one proposed recently by Gibbons and Turok, we investigate the probability that single-field inflation with a polynomial potential can last long enough to solve the shortcomings of the standard hot big bang model, within the semiclassical regime of loop quantum cosmology. We conclude that, for such a class of inflationary models and for natural values of the loop quantum cosmology parameters, a successful inflationary scenario is highly improbable.

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

    SciTech Connect

    Baily, Scott A.; Dalmas, Dale Allen; Wheat, Robert Mitchell; Woloshun, Keith Albert; Dale, Gregory E.

    2015-11-16

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

  9. Space Station evolution study oxygen loop closure

    NASA Technical Reports Server (NTRS)

    Wood, M. G.; Delong, D.

    1993-01-01

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

  10. Oklahoma City Revitalization

    EPA Pesticide Factsheets

    Since the beginning of their Brownfields Program in 2003, Oklahoma City has been the recipient of nine EPA Brownfields Grants, creating a new city from the inside out. So far, 45 properties have been assessed and/or remediated.

  11. Revitalizing Nuclear Safety Research.

    ERIC Educational Resources Information Center

    National Academy of Sciences - National Research Council, Washington, DC.

    This report covers the general issues involved in nuclear safety research and points out the areas needing detailed consideration. Topics included are: (1) "Principles of Nuclear Safety Research" (examining who should fund, who should conduct, and who should set the agenda for nuclear safety research); (2) "Elements of a Future…

  12. Faculty Retirement Transitions Revitalized

    ERIC Educational Resources Information Center

    Van Ummersen, Claire; Duranleau, Lauren; McLaughlin, Jean

    2013-01-01

    It has been almost ten years since the American Council on Education (ACE) began to raise awareness of the importance of workplace flexibility in faculty careers and to encourage colleges and universities to support faculty in better integrating their professional and personal lives. With the generous support of the Alfred P. Sloan Foundation, ACE…

  13. Lightside Atmospheric Revitalization System

    NASA Technical Reports Server (NTRS)

    Colling, A. K.; Cushman, R. J.; Hultman, M. M.; Nason, J. R.

    1980-01-01

    The system was studied as a replacement to the present baseline LiOH system for extended duration shuttle missions. The system consists of three subsystems: a solid amine water desorbed regenerable carbon dioxide removal system, a water vapor electrolysis oxygen generating system, and a Sabatier reactor carbon dioxide reduction system. The system is designed for use on a solar powered shuttle vehicle. The majority of the system's power requirements are utilized on the Sun side of each orbit, when solar power is available.

  14. Peer Review Undergoing Revitalization

    ERIC Educational Resources Information Center

    Sawchuk, Stephen

    2009-01-01

    Established in the 142,000-student Montgomery County, Maryland, district in 1999, peer assistance and review (PAR)--or "peer review," as it is occasionally called--is actually an old idea. In 1981, the then-president of the Toledo Federation of Teachers, Dal Lawrence, helped create the first PAR program. Almost 30 years later, only a…

  15. Revitalizing HEC at NASA

    NASA Technical Reports Server (NTRS)

    Brooks, Walt

    2005-01-01

    This talk will review the focus on NASA advances in SSI supercomputing technology over the last 4 years, the development of the worlds largest Origins. the development of the cooperative program that developed the CRAY and SGI system in FY03 and the efforts that led to the formulation and approval of the NAS program and Columbia Project. Finally a projection of the RBD and operations focus in HEC for the next 3-5 years will be described. (use NAS url)

  16. Community Parks Revitalization Act

    THOMAS, 112th Congress

    Sen. Hagan, Kay R. [D-NC

    2012-09-20

    09/20/2012 Read twice and referred to the Committee on Banking, Housing, and Urban Affairs. (text of measure as introduced: CR S6549-6552) (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

  17. Hybrid Combustion-Gasification Chemical Looping

    SciTech Connect

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

    2009-01-07

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

  18. Investigation of air transportation technology at Princeton University, 1986

    NASA Technical Reports Server (NTRS)

    Stengel, Robert F.

    1988-01-01

    The Air Transportation Technology Program at Princeton proceeded along four avenues: Guidance and control strategies for penetration of microbursts and wind shear; Application of artificial intelligence in flight control systems; Computer aided control system design; and Effects of control saturation on closed loop stability and response of open loop unstable aircraft. Areas of investigation relate to guidance and control of commercial transports as well as general aviation aircraft. Interaction between the flight crew and automatic systems is a subject of prime concern.

  19. Development of a Forced-Convection Liquid-Fluoride-Salt Test Loop

    SciTech Connect

    Yoder Jr, Graydon L; Wilson, Dane F; Peretz, Fred J; Wilgen, John B; Romanoski, Glenn R; Kisner, Roger A; Holcomb, David Eugene; Heatherly, Dennis Wayne; Aaron, Adam M

    2010-01-01

    A small forced-convection molten-fluoride-salt loop is being constructed at Oak Ridge National Laboratory to examine the heat transfer behavior of FLiNaK salt in a heated pebble bed. Objectives of the experiment include reestablishing infrastructure needed for fluoride-salt loop testing, developing a unique inductive heating technique for performing heat transfer (or other) experiments, measuring heat transfer characteristics in a liquid-fluoride-salt-cooled pebble bed, and demonstrating the use of silicon carbide (SiC) as a structural component for salt systems. The salt loop will consist of an Inconel 600 piping system, a sump-type pump, a SiC test section, and an air-cooled heat exchanger, as well as auxiliary systems needed to pre-heat the loop, transport salt into and out of the loop, and maintain an inert cover gas over the salt. A 30,000 Hz inductive heating system will be used to provide up to 250 kW of power to a 15 cm diameter SiC test section containing a packed bed of 3 cm graphite spheres. A SiC-to-Inconel 600 joint will use a conventional nickel/grafoil spiral wound gasket sandwiched between SiC and Inconel flanges. The loop system can provide up to 4.5 kg/s of salt flow at a head of 0.125 MPa and operate at a pressure just above atmospheric. Pebble Reynolds numbers of up to 2600 are possible with this configuration. A sump system is provided to drain and store the salt when not in use. Instrumentation on the loop will include pressure, temperature, and flow measurements, while the test section will be instrumented to provide pebble and FLiNaK temperatures.

  20. Air transport

    NASA Technical Reports Server (NTRS)

    Page, F Handley

    1924-01-01

    I purpose (sic) in this paper to deal with the development in air transport which has taken place since civil aviation between England and the Continent first started at the end of August 1919. A great deal of attention has been paid in the press to air services of the future, to the detriment of the consideration of results obtained up to the present.

  1. Air Pollution.

    ERIC Educational Resources Information Center

    Fox, Donald L.

    1989-01-01

    Materials related to air pollution are reviewed for the period January 1987, to October 1988. The topics are pollution monitoring, air pollution, and environmental chemistry. The organization consists of two major analytical divisions: (1) gaseous methods; and (2) aerosol and particulate methods. (MVL)

  2. Air Pollution.

    EPA Science Inventory

    Air quality is affected by many types of pollutants that are emitted from various sources, including stationary and mobile. These sources release both criteria and hazardous air pollutants, which cause health effects, ecological harm, and material damage. They are generally categ...

  3. LOOP CALCULUS AND BELIEF PROPAGATION FOR Q-ARY ALPHABET: LOOP TOWER

    SciTech Connect

    CHERTKOV, MICHAEL; CHERNYAK, VLADIMIR

    2007-01-10

    Loop calculus introduced in [1], [2] constitutes a new theoretical tool that explicitly expresses symbol Maximum-A-Posteriori (MAP) solution of a general statistical inference problem via a solution of the Belief Propagation (BP) equations. This finding brought a new significance to the BP concept, which in the past was thought of as just a loop-free approximation. In this paper they continue a discussion of the Loop Calculus, partitioning the results into three Sections. In Section 1 they introduce a new formulation of the Loop Calculus in terms of a set of transformations (gauges) that keeping the partition function of the problem invariant. The full expression contains two terms referred to as the 'ground state' and 'excited states' contributions. The BP equations are interpreted as a special (BP) gauge fixing condition that emerges as a special orthogonality constraint between the ground state and excited states, which also selects loop contributions as the only surviving ones among the excited states. In Section 2 they demonstrate how the invariant interpretation of the Loop Calculus, introduced in Section 1, allows a natural extension to the case of a general q-ary alphabet, this is achieved via a loop tower sequential construction. The ground level in the tower is exactly equivalent to assigning one color (out of q available) to the 'ground state' and considering all 'excited' states colored in the remaining (q-1) colors, according to the loop calculus rule. Sequentially, the second level in the tower corresponds to selecting a loop from the previous step, colored in (q-1) colors, and repeating the same ground vs excited states splitting procedure into one and (q-2) colors respectively. The construction proceeds till the full (q-1)-levels deep loop tower (and the corresponding contributions to the partition function) are established. In Section 3 they discuss an ultimate relation between the loop calculus and the Bethe-Free energy variational approach of [3].

  4. An Antibody Loop Replacement Design Feasibility Study and a Loop-Swapped Dimer Structure

    SciTech Connect

    Clark, L.; Boriack-Sjodin, P; Day, E; Eldredge, J; Fitch, C; Jarpe, M; Miller, S; Li, Y; Simon, K; van Vlijmen, H

    2009-01-01

    A design approach was taken to investigate the feasibility of replacing single complementarity determining region (CDR) antibody loops. This approach may complement simpler mutation-based strategies for rational antibody design by expanding conformation space. Enormous crystal structure diversity is available, making CDR loops logical targets for structure-based design. A detailed analysis for the L1 loop shows that each loop length takes a distinct conformation, thereby allowing control on a length scale beyond that accessible to simple mutations. The L1 loop in the anti-VLA1 antibody was replaced with the L2 loop residues longer in an attempt to add an additional hydrogen bond and fill space on the antibody-antigen interface. The designs expressed well, but failed to improve affinity. In an effort to learn more, one design was crystallized and data were collected at 1.9 {angstrom} resolution. The designed L1 loop takes the qualitatively desired conformation; confirming that loop replacement by design is feasible. The crystal structure also shows that the outermost loop (residues Leu51-Ser68) is domain swapped with another monomer. Tryptophan fluorescence measurements were used to monitor unfolding as a function of temperature and indicate that the loop involved in domain swapping does not unfold below 60C. The domain-swapping is not directly responsible for the affinity loss, but is likely a side-effect of the structural instability which may contribute to affinity loss. A second round of design was successful in eliminating the dimerization through mutation of a residue (Leu51Ser) at the joint of the domain-swapped loop.

  5. The West End Revitalization Association (WERA)'s right to basic amenities movement: voice and language of ownership and management of public health solutions in Mebane, North Carolina.

    PubMed

    Wilson, Omega R; Bumpass, Natasha G; Wilson, Omari M; Snipes, Marilyn H

    2008-01-01

    The West End Revitalization Association (WERA) cultivated strategies for assessing environmental hazards, managing stakeholder participation, and implementing corrective actions in three low-income African American communities in Mebane, North Carolina. The community voices evolved into language to drive WERA's "Right to Basic Amenities Movement" as a way to address health, legal, and quality-of-life disparities. The sustainability of this movement depends on communicating a solutions process with funding equity. Disparities are a way of life for impacted residents: dusty dead-end streets, contaminated drinking water, failed backyard septic tanks, and putrid odors. WERA organized on "common knowledge" for effective use of public health statutes and Title VI of the Civil Rights Act of 1964. WERA's board, staff, and volunteers exercised their voices in the language of government, public health, university research, and legal agencies. WERA's best practices and lessons learned may influence public policy in comparable communities in North Carolina and throughout the nation.

  6. Detection and Characterization of R Loop Structures.

    PubMed

    Boque-Sastre, Raquel; Soler, Marta; Guil, Sonia

    2017-01-01

    R loops are special three stranded nucleic acid structures that comprise a nascent RNA hybridized with the DNA template strand, leaving a non-template DNA single-stranded. More specifically, R loops form in vivo as G-rich RNA transcripts invade the DNA duplex and anneal to the template strand to generate an RNA:DNA hybrid, leaving the non-template, G-rich DNA strand in a largely single-stranded conformation (Aguilera and Garcia-Muse, Mol Cell 46:115-124, 2012).DNA-RNA hybrids are a natural occurrence within eukaryotic cells, with levels of these hybrids increasing at sites with high transcriptional activity, such as during transcription initiation, repression, and elongation. RNA-DNA hybrids influence genomic instability, and growing evidence points to an important role for R loops in active gene expression regulation (Ginno et al., Mol Cell 45, 814-825, 2012; Sun et al., Science 340: 619-621, 2013; Bhatia et al., Nature 511, 362-365, 2014). Analysis of the occurrence of such structures is therefore of increasing relevance and herein we describe methods for the in vivo and in vitro identification and characterization of R loops in mammalian systems.R loops (DNA:RNA hybrids and the associated single-stranded DNA) have been traditionally associated with threats to genome integrity, making some regions of the genome more prone to DNA-damaging and mutagenic agents. Initially considered to be rare byproducts of transcription, over the last decade accumulating evidence has pointed to a new view in which R loops form more frequently than previously thought. The R loop field has become an increasingly expanded area of research, placing these structures as a major threat to genome stability but also as potential regulators of gene expression. Special interest has arisen as they have also been linked to a variety of diseases, including neurological disorders and cancer, positioning them as potential therapeutic targets [5].

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

    SciTech Connect

    Jarrell, Mark

    2013-09-30

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

  8. Computational fluid dynamics modeling of chemical looping combustion process with calcium sulphate oxygen carrier - article no. A19

    SciTech Connect

    Baosheng Jin; Rui Xiao; Zhongyi Deng; Qilei Song

    2009-07-01

    To concentrate CO{sub 2} in combustion processes by efficient and energy-saving ways is a first and very important step for its sequestration. Chemical looping combustion (CLC) could easily achieve this goal. A chemical-looping combustion system consists of a fuel reactor and an air reactor. Two reactors in the form of interconnected fluidized beds are used in the process: (1) a fuel reactor where the oxygen carrier is reduced by reaction with the fuel, and (2) an air reactor where the reduced oxygen carrier from the fuel reactor is oxidized with air. The outlet gas from the fuel reactor consists of CO{sub 2} and H{sub 2}O, while the outlet gas stream from the air reactor contains only N{sub 2} and some unused O{sub 2}. The water in combustion products can be easily removed by condensation and pure carbon dioxide is obtained without any loss of energy for separation. Until now, there is little literature about mathematical modeling of chemical-looping combustion using the computational fluid dynamics (CFD) approach. In this work, the reaction kinetic model of the fuel reactor (CaSO{sub 4}+ H{sub 2}) is developed by means of the commercial code FLUENT and the effects of partial pressure of H{sub 2} (concentration of H{sub 2}) on chemical looping combustion performance are also studied. The results show that the concentration of H{sub 2} could enhance the CLC performance.

  9. Suppressing Transients In Digital Phase-Locked Loops

    NASA Technical Reports Server (NTRS)

    Thomas, J. B.

    1993-01-01

    Loop of arbitrary order starts in steady-state lock. Method for initializing variables of digital phase-locked loop reduces or eliminates transients in phase and frequency typically occurring during acquisition of lock on signal or when changes made in values of loop-filter parameters called "loop constants". Enables direct acquisition by third-order loop without prior acquisition by second-order loop of greater bandwidth, and eliminates those perturbations in phase and frequency lock occurring when loop constants changed by arbitrarily large amounts.

  10. Acquisition Performances Of QPSK Carrier-Tracking Loops

    NASA Technical Reports Server (NTRS)

    Hinedi, Sami M.; Shah, Biren N.

    1992-01-01

    Report presents comparative study of acquisition performances of several types of carrier-signal-tracking loops for reception of quadrature phase-shift keying (QPSK) signals. Loops classified into three types: maximum a-posteriori, (MAP) estimation loop, Costas cross-over loop, and generalized Costas loop. Mathematical models developed. In-phase and quadrature signals generated numerically and processed according to loop algorithms. Results show though MAP loop produces smallest squaring loss at all signal-to-noise ratios, others sometimes exhibit shorter acquisition time and greater probability of acquisition.

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

    NASA Astrophysics Data System (ADS)

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

    2005-10-01

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

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

    ERIC Educational Resources Information Center

    Cetin, Ibrahim

    2015-01-01

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

  13. Parameterizing loop fusion for automated empirical tuning

    SciTech Connect

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

    2005-12-15

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

  14. ABJ Wilson loops and Seiberg duality

    NASA Astrophysics Data System (ADS)

    Shinji, Hirano; Keita, Nii; Masaki, Shigemori

    2014-11-01

    We study supersymmetric Wilson loops in the {N} = 6 supersymmetric U(N_1)_k × U(N_2)_{-k} Chern-Simons-matter (CSM) theory, the ABJ theory, at finite N_1, N_2, and k. This generalizes our previous study on the ABJ partition function. First computing the Wilson loops in the U(N_1) × U(N_2) lens space matrix model exactly, we perform an analytic continuation, N_2 to -N_2, to obtain the Wilson loops in the ABJ theory that is given in terms of a formal series and is only valid in perturbation theory. Via a Sommerfeld-Watson-type transform, we provide a nonperturbative completion that renders the formal series well defined at all couplings. This is given by min (N_1,N_2)-dimensional integrals that generalize the “mirror description” of the partition function of the ABJM theory. Using our results, we find the maps between the Wilson loops in the original and Seiberg dual theories and prove the duality. In our approach we can explicitly see how the perturbative and nonperturbative contributions to the Wilson loops are exchanged under the duality. The duality maps are further supported by a heuristic yet very useful argument based on the brane configuration as well as an alternative derivation based on that of Kapustin and Willett (arXiv:1302.2164 [hep-th]).

  15. 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.

  16. Bootstrapping the Three-Loop Hexagon

    SciTech Connect

    Dixon, Lance J.; Drummond, James M.; Henn, Johannes M.; /Humboldt U., Berlin /Santa Barbara, KITP

    2011-11-08

    We consider the hexagonal Wilson loop dual to the six-point MHV amplitude in planar N = 4 super Yang-Mills theory. We apply constraints from the operator product expansion in the near-collinear limit to the symbol of the remainder function at three loops. Using these constraints, and assuming a natural ansatz for the symbol's entries, we determine the symbol up to just two undetermined constants. In the multi-Regge limit, both constants drop out from the symbol, enabling us to make a non-trivial confirmation of the BFKL prediction for the leading-log approximation. This result provides a strong consistency check of both our ansatz for the symbol and the duality between Wilson loops and MHV amplitudes. Furthermore, we predict the form of the full three-loop remainder function in the multi-Regge limit, beyond the leading-log approximation, up to a few constants representing terms not detected by the symbol. Our results confirm an all-loop prediction for the real part of the remainder function in multi-Regge 3 {yields} 3 scattering. In the multi-Regge limit, our result for the remainder function can be expressed entirely in terms of classical polylogarithms. For generic six-point kinematics other functions are required.

  17. Power supply with air core transformer and seperated power supplies for high dynamic range

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Aalami, Dean (Inventor); Darrach, Murray (Inventor); Orient, Otto (Inventor)

    2001-01-01

    A power supply for a quadrupole mass spectrometer which operates using an RF signal. The RF signal is controllable via a feedback loop. The feedback loop is from the output, through a comparator, and compared to a digital signal. An air core transformer is used to minimize the weight. The air core transformer is driven via two out of phase sawtooth signals which drive opposite ends of the transformer.

  18. Congenital preretinal arterial loop: Is it a misnomer?

    PubMed Central

    Raman, Rajiv; Gella, Laxmi; Kazi, M. S.

    2017-01-01

    We describe a case of recurrent spontaneous vitreous haemorrhage due to congenital retinal arterial loop. The pre-optical coherence tomography showed the loop to be intraretinal rather than pre retinal. Thus the term pre retinal arterial loop is a misnomer. The arterial loop is in the superficial layer of retinal nerve fiber layer. We also demonstrated preretinal posterior hyaloid tissue attached on the retinal arterial loop, which may be the cause of traction and spontaneous recurrent VH. PMID:28298870

  19. Linear phase demodulator including a phase locked loop with auxiliary feedback loop

    NASA Technical Reports Server (NTRS)

    Rippy, R. R. (Inventor)

    1976-01-01

    A phase modulated wave that may have no carrier power is demodulated by a phase locked loop including a phase detector for deriving an A.C. data output signal having a magnitude and a phase indicative of the phase of the modulated wave. A feedback loop responsive to the data output signal restores power to the carrier frequency component to the loop. In one embodiment, the feedback loop includes a phase modulator responsive to the phase modulated wave and the data output signal. In a second embodiment, carrier frequency power is restored by differentiating the data output signal and supplying the differentiated signal to an input of a voltage controlled oscillator included in the phase locked loop.

  20. Direct digital control of air washer cooling system

    SciTech Connect

    Elben, T.; Roseblock, R.; Lawler, R.; McCord, J.

    1990-01-01

    The purpose of this project was to make a practical evaluation of using new technology to extend the life of obsolete HVAC mechanical equipment. The specific exercises in this project involved the application of software driven control algorithms to operate and manage open loop air washer cooling systems in the air handling units located in the Municipal Auditorium in Kansas City, Missouri. The specific opportunity evaluated in this project involved eight air handling units at the Municipal Auditorium. The air handling systems utilize outdated air washer cooling systems that provide air conditioning and dehumidification to the areas they serve. We utilized direct digital control to assume total control of the operation of the air handling units. We also found it necessary to upgrade some components of the air handling units in order to allow the new control applications to execute their functions. This report describes the plan used to execute the project and the results. 20 tabs.

  1. Closed-Loop Life Support Systems

    NASA Technical Reports Server (NTRS)

    Fisher, John W.

    2003-01-01

    Contents include the following: 1. Advanced life support requirements document-high level: (a) high level requirements and standards, (b) advanced life support requirements documents-air, food, water. 2. Example technologies that satisfy requrements: air system-carbon dioxide removal. 3. Air-sabatter. 4. International Space Station water treatment subsystem.5. Direct osmotic concentrator. 6. Mass, volume and power estimates.

  2. Loop Quantum Gravity and Asymptotically Flat Spaces

    NASA Astrophysics Data System (ADS)

    Arnsdorf, Matthias

    2002-12-01

    Remarkable progress has been made in the field of non-perturbative (loop) quantum gravity in the last decade or so and it is now a rigorously defined kinematical theory (c.f. [5] for a review and references). We are now at the stage where physical applications of loop quantum gravity can be studied and used to provide checks for the consistency of the quantisation programme. Equally, old fundamental problems of canonical quantum gravity such as the problem of time or the interpretation of quantum cosmology need to be reevaluated seriously. These issues can be addressed most profitably in the asymptotically flat sector of quantum gravity. Indeed, it is likely that we should obtain a quantum theory for this special case even if it is not possible to quantise full general relativity. The purpose of this summary is to advertise the extension of loop quantum gravity to this sector that was developed in [1]...

  3. Double reference pulsed phase locked loop

    NASA Technical Reports Server (NTRS)

    Heyman, J. S. (Inventor)

    1986-01-01

    A double reference pulse phase locked loop is described which measures the phase shift between tone burst signals initially derived from the same periodic signal source (voltage controlled oscillator) and delayed by different amounts because of two different paths. A first path is from the transducer to the surface of a sample and back. A second path is from the transducer to the opposite surface and back. A first pulse phase locked loop including a phase detector and a phase shifter forces the tone burst signal delayed by the second path in phase quadrature with the periodic signal source. A second pulse phase locked loop including a second phase detector forces the tone burst signals delayed by the first path into phase quadrature with the phase shifted periodic signal source.

  4. Mass flow in loop type coronal transients

    NASA Technical Reports Server (NTRS)

    Anzer, U.; Poland, A. I.

    1979-01-01

    Coronal transients having characteristics of a well-defined loop structure are examined, particularly with respect to temporal changes in the density and mass per unit length along the loop over periods of several days after the initial eruption. Measurements of mass distributions as a function of time are presented for eight transients, and one particular transient with a fairly simple configuration is investigated in more detail. Theoretical calculations are combined with the masses and densities derived from the observations to obtain estimates of the material flow in the transients; this flow is modeled on the assumption that magnetic forces drive and confine the loop. The flow field is found to be diverging everywhere, indicating that the density decreases in time. It is inferred that the transient legs are approximately in hydrostatic equilibrium and that most of the mass of the transient is lost from the sun during the initial phase.

  5. Closed-loop approach to thermodynamics

    NASA Astrophysics Data System (ADS)

    Goupil, C.; Ouerdane, H.; Herbert, E.; Benenti, G.; D'Angelo, Y.; Lecoeur, Ph.

    2016-09-01

    We present the closed-loop approach to linear nonequilibrium thermodynamics considering a generic heat engine dissipatively connected to two temperature baths. The system is usually quite generally characterized by two parameters: the output power P and the conversion efficiency η , to which we add a third one, the working frequency ω . We establish that a detailed understanding of the effects of the dissipative coupling on the energy conversion process requires only knowing two quantities: the system's feedback factor β and its open-loop gain A0, which product A0β characterizes the interplay between the efficiency, the output power, and the operating rate of the system. By raising the abstract hermodynamic analysis to a higher level, the feedback loop approach provides a versatile and economical, hence fairly efficient, tool for the study of any conversion engine operation for which a feedback factor can be defined.

  6. Counting primary loops in polymer gels

    PubMed Central

    Zhou, Huaxing; Woo, Jiyeon; Cok, Alexandra M.; Wang, Muzhou; Olsen, Bradley D.; Johnson, Jeremiah A.

    2012-01-01

    Much of our fundamental knowledge related to polymer networks is built on an assumption of ideal end-linked network structure. Real networks invariably possess topological imperfections that negatively affect mechanical properties; modifications of classical network theories have been developed to account for these defects. Despite decades of effort, there are no known experimental protocols for precise quantification of even the simplest topological network imperfections: primary loops. Here we present a simple conceptual framework that enables primary loop quantification in polymeric materials. We apply this framework to measure the fraction of primary loop junctions in trifunctional PEG-based hydrogels. We anticipate that the concepts described here will open new avenues of theoretical and experimental research related to polymer network structure. PMID:23132947

  7. Digital tanlock loop architecture with no delay

    NASA Astrophysics Data System (ADS)

    Al-Kharji AL-Ali, Omar; Anani, Nader; Al-Araji, Saleh; Al-Qutayri, Mahmoud; Ponnapalli, Prasad

    2012-02-01

    This article proposes a new architecture for a digital tanlock loop which eliminates the time-delay block. The ? (rad) phase shift relationship between the two channels, which is generated by the delay block in the conventional time-delay digital tanlock loop (TDTL), is preserved using two quadrature sampling signals for the loop channels. The proposed system outperformed the original TDTL architecture, when both systems were tested with frequency shift keying input signal. The new system demonstrated better linearity and acquisition speed as well as improved noise performance compared with the original TDTL architecture. Furthermore, the removal of the time-delay block enables all processing to be digitally performed, which reduces the implementation complexity. Both the original TDTL and the new architecture without the delay block were modelled and simulated using MATLAB/Simulink. Implementation issues, including complexity and relation to simulation of both architectures, are also addressed.

  8. Current loop signal conditioning: Practical applications

    NASA Technical Reports Server (NTRS)

    Anderson, Karl F.

    1995-01-01

    This paper describes a variety of practical application circuits based on the current loop signal conditioning paradigm. Equations defining the circuit response are also provided. The constant current loop is a fundamental signal conditioning circuit concept that can be implemented in a variety of configurations for resistance-based transducers, such as strain gages and resistance temperature detectors. The circuit features signal conditioning outputs which are unaffected by extremely large variations in lead wire resistance, direct current frequency response, and inherent linearity with respect to resistance change. Sensitivity of this circuit is double that of a Wheatstone bridge circuit. Electrical output is zero for resistance change equals zero. The same excitation and output sense wires can serve multiple transducers. More application arrangements are possible with constant current loop signal conditioning than with the Wheatstone bridge.

  9. Air Apparent.

    ERIC Educational Resources Information Center

    Harbster, David A.

    1988-01-01

    Explains the principle upon which a barometer operates. Describes how to construct two barometric devices for use in the classroom that show air's changing pressure. Cites some conditions for predicting weather. (RT)

  10. Air Abrasion

    MedlinePlus

    ... information you need from the Academy of General Dentistry Sunday, April 9, 2017 About | Contact InfoBites Quick ... general dentist, who has been trained in restorative dentistry techniques, will perform any procedures that use air- ...

  11. Quantum Monte Carlo with directed loops.

    PubMed

    Syljuåsen, Olav F; Sandvik, Anders W

    2002-10-01

    We introduce the concept of directed loops in stochastic series expansion and path-integral quantum Monte Carlo methods. Using the detailed balance rules for directed loops, we show that it is possible to smoothly connect generally applicable simulation schemes (in which it is necessary to include backtracking processes in the loop construction) to more restricted loop algorithms that can be constructed only for a limited range of Hamiltonians (where backtracking can be avoided). The "algorithmic discontinuities" between general and special points (or regions) in parameter space can hence be eliminated. As a specific example, we consider the anisotropic S=1/2 Heisenberg antiferromagnet in an external magnetic field. We show that directed-loop simulations are very efficient for the full range of magnetic fields (zero to the saturation point) and anisotropies. In particular, for weak fields and anisotropies, the autocorrelations are significantly reduced relative to those of previous approaches. The back-tracking probability vanishes continuously as the isotropic Heisenberg point is approached. For the XY model, we show that back tracking can be avoided for all fields extending up to the saturation field. The method is hence particularly efficient in this case. We use directed-loop simulations to study the magnetization process in the two-dimensional Heisenberg model at very low temperatures. For LxL lattices with L up to 64, we utilize the step structure in the magnetization curve to extract gaps between different spin sectors. Finite-size scaling of the gaps gives an accurate estimate of the transverse susceptibility in the thermodynamic limit: chi( perpendicular )=0.0659+/-0.0002.

  12. Coronal Loops: Evolving Beyond the Isothermal Approximation

    NASA Astrophysics Data System (ADS)

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

    2002-05-01

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

  13. Detecting air traffic controller interventions in recorded air transportation system data

    NASA Astrophysics Data System (ADS)

    Kwon, Yul

    In this study, I propose a systematic method of detecting aircraft deviation due to air traffic controller (ATC) intervention. The aircraft deviations associated with ATC interventions are detected using a heuristic algorithm developed from analyzing the actual positions of an aircraft to its filed flight plan when the aircraft trajectories were identified as having an encounter in a loss-of-separation incident. An actual (closed-loop) flight trajectory of the Cleveland Air Route Traffic Control Center (ZOB ARTCC) was collected from the FlightAware database. This was compared with the corresponding planned (open-loop) trajectory dataset generated by the Microsoft(c) Flight Simulator X (FSX). I implemented a conflict-detection algorithm in Matlab to identify open-loop flight trajectories that encounters in loss-of-separation. I analyzed the differences between the closed-loop and open-loop flight trajectories of aircrafts that were identified to have encounters in loss of separation. The analysis identified operationally significant deviations in the closed-loop trajectory data with respect to the horizontal paths of the aircrafts. I then developed and validated a heuristic algorithm, the ATC intervention detection algorithm, based on the findings from the analysis. When used with a test dataset to validate the algorithm, it achieved an 85.7% detection rate in detecting horizontal deviations made by the ATC in resolving identified conflicts, and a false-alarm rate of 68%. In addition to the ATC intervention detection algorithm, I present in this paper an analysis of deviated flight trajectories in an effort to display how the presented methodology can be utilized to provide insight into air traffic controller resolution strategies.

  14. Coronal Loops: Observations and Modeling of Confined Plasma.

    PubMed

    Reale, Fabio

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

  15. Quasi-periodic processes in the flare loop generated by sudden temperature enhancements at loop footpoints

    NASA Astrophysics Data System (ADS)

    Karlický, M.; Jelínek, P.

    2016-05-01

    Aims: During the impulsive flare phase, the plasma at the flare loop footpoints is rapidly heated by particle beams. In the present paper, we study processes that occur after this sudden heating in a two-dimensional magnetic loop. Methods: We adopt a 2D magnetohydrodynamic (MHD) model, in which we solve a full set of the ideal time-dependent MHD equations by means of the FLASH code, using the adaptive mesh refinement (AMR) method. Periods in the processes are estimated by the wavelet analysis technique. Results: We consider a model of the solar atmosphere with a symmetric magnetic loop. The length of this loop in the corona is approximately 21.5 Mm. At both loop footpoints, at the transition region, we initiate the Gaussian temperature (pressure) perturbation with the maximum temperature 14, 7, or 3.5 times higher than the unperturbed temperature. In the corona, the perturbations produce supersonic blast shocks with the Mach number of about 1.1, but well below Alfvén velocities. We consider cases with the same perturbations at both footpoints (symmetric case) and one with different perturbations (asymmetric case). In the symmetric case, the shocks move along both loop legs upwards to the top of the loop, where they interact and form a transient compressed region. Then they continue in their motion to the transition region at the opposite side of the loop, where they are reflected upwards, and so on. At the top of the loop, the shock appears periodically with the period of about 170 s. In the loop legs during this period, a double peak of the plasma parameters, which is connected with two arrivals of shocks, is detected: firstly, when the shock moves up and then when the shock, propagating from the opposite loop leg, moves down. Increasing the distance of the detection point in the loop leg from the top of the loop, the time interval between these shock arrivals increases. Thus, at these detection points, the processes with shorter periods can be detected. After

  16. Loop Optimization for Tensor Network Renormalization

    NASA Astrophysics Data System (ADS)

    Yang, Shuo; Gu, Zheng-Cheng; Wen, Xiao-Gang

    2017-03-01

    We introduce a tensor renormalization group scheme for coarse graining a two-dimensional tensor network that can be successfully applied to both classical and quantum systems on and off criticality. The key innovation in our scheme is to deform a 2D tensor network into small loops and then optimize the tensors on each loop. In this way, we remove short-range entanglement at each iteration step and significantly improve the accuracy and stability of the renormalization flow. We demonstrate our algorithm in the classical Ising model and a frustrated 2D quantum model.

  17. Temperature Oscillations in Loop Heat Pipe Operation

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Ottenstein, Laura; Kobel, Mark; Rogers, Paul; Kaya, Tarik; Paquin, Krista C. (Technical Monitor)

    2000-01-01

    Loop heat pipes (LHPs) are versatile two-phase heat transfer devices that have gained increasing acceptance for space and terrestrial applications. The operating temperature of an LHP is a function of its operating conditions. The LHP usually reaches a steady operating temperature for a given heat load and sink temperature. The operating temperature will change when the heat load and/or the sink temperature changes, but eventually reaches another steady state in most cases. Under certain conditions, however, the loop operating temperature never really reaches a true steady state, but instead becomes oscillatory. This paper discusses the temperature oscillation phenomenon using test data from a miniature LHP.

  18. Anomaly freedom in perturbative loop quantum gravity

    SciTech Connect

    Bojowald, Martin; Hossain, Golam Mortuza; Kagan, Mikhail; Shankaranarayanan, S.

    2008-09-15

    A fully consistent linear perturbation theory for cosmology is derived in the presence of quantum corrections as they are suggested by properties of inverse volume operators in loop quantum gravity. The underlying constraints present a consistent deformation of the classical system, which shows that the discreteness in loop quantum gravity can be implemented in effective equations without spoiling space-time covariance. Nevertheless, nontrivial quantum corrections do arise in the constraint algebra. Since correction terms must appear in tightly controlled forms to avoid anomalies, detailed insights for the correct implementation of constraint operators can be gained. The procedures of this article thus provide a clear link between fundamental quantum gravity and phenomenology.

  19. Three loop cusp anomalous dimension in QCD.

    PubMed

    Grozin, Andrey; Henn, Johannes M; Korchemsky, Gregory P; Marquard, Peter

    2015-02-13

    We present the full analytic result for the three loop angle-dependent cusp anomalous dimension in QCD. With this result, infrared divergences of planar scattering processes with massive particles can be predicted to that order. Moreover, we define a closely related quantity in terms of an effective coupling defined by the lightlike cusp anomalous dimension. We find evidence that this quantity is universal for any gauge theory and use this observation to predict the nonplanar n(f)-dependent terms of the four loop cusp anomalous dimension.

  20. LCL Current Control Loop Stability Design

    NASA Astrophysics Data System (ADS)

    Delepaut, Christophe; Kuremyr, Tobias; Martin, Manuel; Tonicello, Ferdinando

    2014-08-01

    Latching Current Limiters include a control loop meant at limiting the current in case of downstream failure. Such current control loop consists typically of a simple proportional feedback gain from a current measurement shunt resistance and may result in very limited phase margin for specified operating conditions. The present paper investigates the combination of a proportional and derivative feedback to mitigate the lack of stability margin, providing a comprehensive overview on designing Latching Current Limiters for stability. For illustration purpose, a LCL based on radiation hardened ITAR free components is considered. A breadboard has been manufactured and the reported phase margin measurements demonstrate performances in line with the analytic results.

  1. Similarity Metrics for Closed Loop Dynamic Systems

    NASA Technical Reports Server (NTRS)

    Whorton, Mark S.; Yang, Lee C.; Bedrossian, Naz; Hall, Robert A.

    2008-01-01

    To what extent and in what ways can two closed-loop dynamic systems be said to be "similar?" This question arises in a wide range of dynamic systems modeling and control system design applications. For example, bounds on error models are fundamental to the controller optimization with modern control design methods. Metrics such as the structured singular value are direct measures of the degree to which properties such as stability or performance are maintained in the presence of specified uncertainties or variations in the plant model. Similarly, controls-related areas such as system identification, model reduction, and experimental model validation employ measures of similarity between multiple realizations of a dynamic system. Each area has its tools and approaches, with each tool more or less suited for one application or the other. Similarity in the context of closed-loop model validation via flight test is subtly different from error measures in the typical controls oriented application. Whereas similarity in a robust control context relates to plant variation and the attendant affect on stability and performance, in this context similarity metrics are sought that assess the relevance of a dynamic system test for the purpose of validating the stability and performance of a "similar" dynamic system. Similarity in the context of system identification is much more relevant than are robust control analogies in that errors between one dynamic system (the test article) and another (the nominal "design" model) are sought for the purpose of bounding the validity of a model for control design and analysis. Yet system identification typically involves open-loop plant models which are independent of the control system (with the exception of limited developments in closed-loop system identification which is nonetheless focused on obtaining open-loop plant models from closed-loop data). Moreover the objectives of system identification are not the same as a flight test and

  2. A double-loop tracking system.

    NASA Technical Reports Server (NTRS)

    Yuen, J. H.

    1972-01-01

    A nonlinear analysis which can be used to assess certain statistical characteristics of double-loop tracking systems is presented. It takes into account the mutual coupling effects of the loops in the system. Two approaches are taken to obtain steady-state probability density functions (pdf's) of the system phase errors. From these pdf's, important system performance statistics, e.g., the phase-error variances, can be calculated, thus illustrating the application and usefulness of the analysis. The analysis is applied to a satellite transponder as an example.

  3. Toward loop quantization of plane gravitational waves

    NASA Astrophysics Data System (ADS)

    Hinterleitner, Franz; Major, Seth

    2012-03-01

    The polarized Gowdy model in terms of Ashtekar-Barbero variables is reduced with an additional constraint derived from the Killing equations for plane gravitational waves with parallel rays. The new constraint is formulated in a diffeomorphism invariant manner and, when it is included in the model, the resulting constraint algebra is first class, in contrast to the prior work done in special coordinates. Using an earlier work by Banerjee and Date, the constraints are expressed in terms of classical quantities that have an operator equivalent in loop quantum gravity, making these plane gravitational wave spacetimes accessible to loop quantization techniques.

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

    PubMed Central

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

    2014-01-01

    Storage and retrieval of the genetic information in cells is a dynamic process that requires the DNA to undergo dramatic structural rearrangements. DNA looping is a prominent example of such a structural rearrangement that is essential for transcriptional regulation in both prokaryotes and eukaryotes, and the speed of such regulations affects the fitness of individuals. Here, we examine the in vitro looping dynamics of the classic Lac repressor gene-regulatory motif. We show that both loop association and loop dissociation at the DNA-repressor junctions depend on the elastic deformation of the DNA and protein, and that both looping and unlooping rates approximately scale with the looping J factor, which reflects the system’s deformation free energy. We explain this observation by transition state theory and model the DNA–protein complex as an effective worm-like chain with twist. We introduce a finite protein–DNA binding interaction length, in competition with the characteristic DNA deformation length scale, as the physical origin of the previously unidentified loop dissociation dynamics observed here, and discuss the robustness of this behavior to perturbations in several polymer parameters. PMID:25411314

  5. Radiation Enhanced Absorption of Frank Loops by Nanovoids in Cu

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Zhang, X.; Wang, J.

    2016-01-01

    Neutron and heavy ion irradiations generally induce voids in metallic materials, and continuous radiations typically result in void swelling and mechanical failure of the irradiated materials. Recent experiments showed that nanovoids in nanotwinned copper could act as sinks for radiation-induced Frank loops, significantly mitigating radiation damage. In this paper, we report on structural evolution of Frank loops under cascades and address the role of nanovoids in absorbing Frank loops in detail by using molecular dynamics simulations. Results show that a stand-alone Frank loop is stable under cascades. When Frank loops are adjacent to nanovoids, the diffusion of a group of atoms from the loop into nanovoids is accomplished via the formation and propagation of dislocation loops. The loop-nanovoid interactions result in the shrinkage of the nanovoids and the Frank loops.

  6. Radiation Enhanced Absorption of Frank Loops by Nanovoids in Cu

    SciTech Connect

    Chen, Youxing; Zhang, Xinghang; Wang, Jian

    2016-11-01

    Neutron and heavy ion irradiation generally induces voids in metallic materials, and continuous radiations typically result in void swelling and mechanical failure of the irradiated materials. Recent experiments showed that nanovoids in nanotwinned copper could act as sinks for radiation-induced Frank loops, significantly mitigating radiation damage [Y. Chen et al., Nat. Commun. 6:7036 (2015)]. In this paper, we report on structural evolution of Frank loops under cascades and address the role of nanovoids in absorbing Frank loops in detail by using molecular dynamics simulations. Results show that a stand-alone Frank loop is stable under cascades. When Frank loops are adjacent to nanovoids, the diffusion of a group of atoms from the loop into nanovoids is accomplished via the formation and propagation of dislocation loops. The loop-nanovoid interactions result in the shrinkage of the nanovoids and the Frank loops.

  7. Radiation Enhanced Absorption of Frank Loops by Nanovoids in Cu

    DOE PAGES

    Chen, Youxing; Zhang, Xinghang; Wang, Jian

    2016-11-01

    Neutron and heavy ion irradiation generally induces voids in metallic materials, and continuous radiations typically result in void swelling and mechanical failure of the irradiated materials. Recent experiments showed that nanovoids in nanotwinned copper could act as sinks for radiation-induced Frank loops, significantly mitigating radiation damage [Y. Chen et al., Nat. Commun. 6:7036 (2015)]. In this paper, we report on structural evolution of Frank loops under cascades and address the role of nanovoids in absorbing Frank loops in detail by using molecular dynamics simulations. Results show that a stand-alone Frank loop is stable under cascades. When Frank loops are adjacentmore » to nanovoids, the diffusion of a group of atoms from the loop into nanovoids is accomplished via the formation and propagation of dislocation loops. The loop-nanovoid interactions result in the shrinkage of the nanovoids and the Frank loops.« less

  8. Switchable dual-wavelength erbium-doped fiber laser based on the photonic crystal fiber loop mirror and chirped fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Guo; Lou, Shu-Qin; Wang, Li-Wen; Li, Hong-Lei; Guo, Tieying; Jian, Shui-Sheng

    2010-03-01

    The switchable dual-wavelength erbium-doped fiber laser (EDFL) with a two-mode photonic crystal fiber (PCF) loop mirror and a chirped fiber Bragg grating (CFBG) at room temperature is proposed and experimentally demonstrated. The two-mode PCF loop mirror is formed by inserting a piece of two-mode PCF into a Sagnac loop mirror, with the air-holes of the PCF intentionally collapsing at the splices. By adjusting the state of the polarization controller (PC) appropriately, the laser can be switched between the stable single- and dual-wavelength operations by means of the polarization hole burning (PHB) and spectral hole burning (SHB) effects.

  9. Closed-loop response properties of a visual interneuron involved in fly optomotor control.

    PubMed

    Ejaz, Naveed; Krapp, Holger G; Tanaka, Reiko J

    2013-01-01

    Due to methodological limitations neural function is mostly studied under open-loop conditions. Normally, however, nervous systems operate in closed-loop where sensory input is processed to generate behavioral outputs, which again change the sensory input. Here, we investigate the closed-loop responses of an identified visual interneuron, the blowfly H1-cell, that is part of a neural circuit involved in optomotor flight and gaze control. Those behaviors may be triggered by attitude changes during flight in turbulent air. The fly analyses the resulting retinal image shifts and performs compensatory body and head rotations to regain its default attitude. We developed a fly robot interface to study H1-cell responses in a 1 degree-of-freedom image stabilization task. Image shifts, induced by externally forced rotations, modulate the cell's spike rate that controls counter rotations of a mobile robot to minimize relative motion between the robot and its visual surroundings. A feedback controller closed the loop between neural activity and the rotation of the robot. Under these conditions we found the following H1-cell response properties: (i) the peak spike rate decreases when the mean image velocity is increased, (ii) the relationship between spike rate and image velocity depends on the standard deviation of the image velocities suggesting adaptive scaling of the cell's signaling range, and (iii) the cell's gain decreases linearly with increasing image accelerations. Our results reveal a remarkable qualitative similarity between the response dynamics of the H1-cell under closed-loop conditions with those obtained in previous open-loop experiments. Finally, we show that the adaptive scaling of the H1-cell's responses, while maximizing information on image velocity, decreases the cell's sensitivity to image accelerations. Understanding such trade-offs in biological vision systems may advance the design of smart vision sensors for autonomous robots.

  10. Electromagnetic Response of a Large Circular Loop Source on a Layered Earth: A New Computation Method

    NASA Astrophysics Data System (ADS)

    Singh, Nagendra Pratap; Mogi, Toru

    2005-01-01

    Integral expressions of electromagnetic (EM) field components due to a large circular loop source carrying an alternating (ac) current and placed on or above the surface of a layered earth model are transformed to such suitable forms that facilitate numerical computation of field response in quasi-static as well as non-quasi-static regions. The improper integrals occurring in expressions of EM field components are evaluated by converting these integrals into the convergent integrals using the process of subtraction or addition of an integral expression inside the integral sign and subsequently adjusting it or its equivalent analytic expression outside the integral sign. The adjusted integral expressions, in turn, are evaluated using the functional relationships described in this paper. The computation method based on this formulation takes into consideration the effects of both conduction as well as displacement currents, and is well suitable for any position of the source loop either in the air or on the surface of the model, in contrary to the earlier methods which face convergence problem. Moreover, the formulation is equally efficient for computing the EM response at any arbitrary receiver position either inside or outside the source loop. For illustrating the accuracy and applicability of the method and studying the nature of EM response of a loop source over a layered earth model, we have applied it for the computation of amplitude and phase of Hz field over the various 2-layer and 3-layer models. Results show their characteristic variations, and depict good resolution for the subsurface layering. The results are in agreement with those of the published results for the quasi-static region, and are new extension of quasi-static variation in the non-quasi-static region. The agreement of computed results with published results demonstrates the accuracy of the method. Moreover, this is the initial presentation of numerical results for an arbitrary in-loop point

  11. Extrasensitive phase-locked-loop circuit

    NASA Technical Reports Server (NTRS)

    Nyiri, E. J.

    1977-01-01

    Modified phase-locked loop (PLL) generates clock from incoming data signal. To minimize effects of threshold phase-detector gain variations, the PLL uses a dither oscillator, a dither band-pass filter, and correlator instead of coherent amplitude detector.

  12. BIOREACTOR DESIGN - OUTER LOOP LANDFILL, LOUISVILLE, KY

    EPA Science Inventory

    Bioreactor field demonstration projects are underway at the Outer Loop Landfill in Louisville, KY, USA. The research effort is a cooperative research effort between US EPA and Waste Management Inc. Two primary kinds of municipal waste bioreactors are under study at this site. ...

  13. Parachute Line Hook Includes Integral Loop Expander

    NASA Technical Reports Server (NTRS)

    Bayless, G. B.

    1983-01-01

    Parachute packing simplified with modified line hook. One person packs parachutes for test recovery vehicles faster than previously two-person team. New line hook includes expander that opens up two locking loops so parachute lines are pulled through them. Parachutes are packed at high pressure to be compressed into limited space available in test vehicles.

  14. Looping for Long-Term Success

    ERIC Educational Resources Information Center

    Coash, Vicki; Watkins, Karen

    2005-01-01

    At Santa Maria Middle School in southwest Phoenix, Arizona, teachers have decided to maintain their relationships with their students by looping through sixth, seventh, and eighth grades. Here, they describe the results of the first three years of the program, discussing the development of their team's priorities and the strategies they embraced…

  15. Can Thermal Nonequilibrium Explain Coronal Loops?

    NASA Technical Reports Server (NTRS)

    Klimchuk, James A.; Karpen, Judy T.; Antiochos, Spiro K.

    2010-01-01

    Any successful model of coronal loops must explain a number of observed properties. For warm (approx. 1 MK) loops, these include: 1. excess density, 2. flat temperature profile, 3. super-hydrostatic scale height, 4. unstructured intensity profile, and 5. 1000-5000 s lifetime. We examine whether thermal nonequilibrium can reproduce the observations by performing hydrodynamic simulations based on steady coronal heating that decreases exponentially with height. We consider both monolithic and multi-stranded loops. The simulations successfully reproduce certain aspects of the observations, including the excess density, but each of them fails in at least one critical way. -Xonolithic models have far too much intensity structure, while multi-strand models are either too structured or too long-lived. Storms of nanoflares remain the only viable explanation for warm loops that has been proposed so far. Our results appear to rule out the widespread existence of heating that is both highly concentrated low in the corona and steady or quasi-steady (slowly varying or impulsive with a rapid cadence). Active regions would have a very different appearance if the dominant heating mechanism had these properties. Thermal nonequilibrium may nonetheless play an important role in prominences and catastrophic cooling e(veen.gts..,coronal rain) that occupy a small fraction of the coronal volume. However, apparent inconsistencies between the models and observations of cooling events have yet to be understood.

  16. Energy Release in Driven Twisted Coronal Loops

    NASA Astrophysics Data System (ADS)

    Bareford, M. R.; Gordovskyy, M.; Browning, P. K.; Hood, A. W.

    2016-01-01

    We investigate magnetic reconnection in twisted magnetic fluxtubes, representing coronal loops. The main goal is to establish the influence of the field geometry and various thermodynamic effects on the stability of twisted fluxtubes and on the size and distribution of heated regions. In particular, we aim to investigate to what extent the earlier idealised models, based on the initially cylindrically symmetric fluxtubes, are different from more realistic models, including the large-scale curvature, atmospheric stratification, thermal conduction and other effects. In addition, we compare the roles of Ohmic heating and shock heating in energy conversion during magnetic reconnection in twisted loops. The models with straight fluxtubes show similar distribution of heated plasma during the reconnection: it initially forms a helical shape, which subsequently becomes very fragmented. The heating in these models is rather uniformly distributed along fluxtubes. At the same time, the hot plasma regions in curved loops are asymmetric and concentrated close to the loop tops. Large-scale curvature has a destabilising influence: less twist is needed for instability. Footpoint convergence normally delays the instability slightly, although in some cases, converging fluxtubes can be less stable. Finally, introducing a stratified atmosphere gives rise to decaying wave propagation, which has a destabilising effect.

  17. Warm inflationary model in loop quantum cosmology

    SciTech Connect

    Herrera, Ramon

    2010-06-15

    A warm inflationary universe model in loop quantum cosmology is studied. In general we discuss the condition of inflation in this framework. By using a chaotic potential, V({phi}){proportional_to}{phi}{sup 2}, we develop a model where the dissipation coefficient {Gamma}={Gamma}{sub 0}=constant. We use recent astronomical observations for constraining the parameters appearing in our model.

  18. Interstitial loop transformations in FeCr

    SciTech Connect

    Béland, Laurent Karim; Osetsky, Yuri N.; Stoller, Roger E.; Xu, Haixuan

    2015-03-27

    Here, we improve the Self-Evolving Atomistic Kinetic Monte Carlo (SEAKMC) algorithm by integrating the Activation Relaxation Technique nouveau (ARTn), a powerful open-ended saddle-point search method, into the algorithm. We use it to investigate the reaction of 37-interstitial 1/2[1 1 1] and 1/2[View the MathML source] loops in FeCr at 10 at.% Cr. They transform into 1/2[1 1 1], 1/2[View the MathML source], [1 0 0] and [0 1 0] 74-interstitial clusters with an overall barrier of 0.85 eV. We find that Cr decoration locally inhibits the rotation of crowdions, which dictates the final loop orientation. Moreover, the final loop orientation depends on the details of the Cr decoration. Generally, a region of a given orientation is favored if Cr near its interface with a region of another orientation is able to inhibit reorientation at this interface more than the Cr present at the other interfaces. Also, we find that substitutional Cr atoms can diffuse from energetically unfavorable to energetically favorable sites within the interlocked 37-interstitial loops conformation with barriers of less than 0.35 eV.

  19. Interstitial loop transformations in FeCr

    DOE PAGES

    Béland, Laurent Karim; Osetsky, Yuri N.; Stoller, Roger E.; ...

    2015-03-27

    Here, we improve the Self-Evolving Atomistic Kinetic Monte Carlo (SEAKMC) algorithm by integrating the Activation Relaxation Technique nouveau (ARTn), a powerful open-ended saddle-point search method, into the algorithm. We use it to investigate the reaction of 37-interstitial 1/2[1 1 1] and 1/2[View the MathML source] loops in FeCr at 10 at.% Cr. They transform into 1/2[1 1 1], 1/2[View the MathML source], [1 0 0] and [0 1 0] 74-interstitial clusters with an overall barrier of 0.85 eV. We find that Cr decoration locally inhibits the rotation of crowdions, which dictates the final loop orientation. Moreover, the final loop orientationmore » depends on the details of the Cr decoration. Generally, a region of a given orientation is favored if Cr near its interface with a region of another orientation is able to inhibit reorientation at this interface more than the Cr present at the other interfaces. Also, we find that substitutional Cr atoms can diffuse from energetically unfavorable to energetically favorable sites within the interlocked 37-interstitial loops conformation with barriers of less than 0.35 eV.« less

  20. Fun with higher-loop Feynman diagrams

    NASA Astrophysics Data System (ADS)

    Luthe, Thomas; Schröder, York

    2016-10-01

    We review recent progress that we have achieved in evaluating the class of fully massive vacuum integrals at five loops. After discussing topics that arise in classification, evaluation and algorithmic codification of this specific set of Feynman integrals, we present some selected new results for their expansions around 4 — 2ε dimensions.