Science.gov

Sample records for active defrost scheme

  1. Activating the Microscale Edge Effect in a Hierarchical Surface for Frosting Suppression and Defrosting Promotion

    PubMed Central

    Chen, Xuemei; Ma, Ruiyuan; Zhou, Hongbo; Zhou, Xiaofeng; Che, Lufeng; Yao, Shuhuai; Wang, Zuankai

    2013-01-01

    Despite extensive progress, current icephobic materials are limited by the breakdown of their icephobicity in the condensation frosting environment. In particular, the frost formation over the entire surface is inevitable as a result of undesired inter-droplet freezing wave propagation initiated by the sample edges. Moreover, the frost formation directly results in an increased frost adhesion, posing severe challenges for the subsequent defrosting process. Here, we report a hierarchical surface which allows for interdroplet freezing wave propagation suppression and efficient frost removal. The enhanced performances are mainly owing to the activation of the microscale edge effect in the hierarchical surface, which increases the energy barrier for ice bridging as well as engendering the liquid lubrication during the defrosting process. We believe the concept of harnessing the surface morphology to achieve superior performances in two opposite phase transition processes might shed new light on the development of novel materials for various applications. PMID:23981909

  2. Activating the microscale edge effect in a hierarchical surface for frosting suppression and defrosting promotion.

    PubMed

    Chen, Xuemei; Ma, Ruiyuan; Zhou, Hongbo; Zhou, Xiaofeng; Che, Lufeng; Yao, Shuhuai; Wang, Zuankai

    2013-01-01

    Despite extensive progress, current icephobic materials are limited by the breakdown of their icephobicity in the condensation frosting environment. In particular, the frost formation over the entire surface is inevitable as a result of undesired inter-droplet freezing wave propagation initiated by the sample edges. Moreover, the frost formation directly results in an increased frost adhesion, posing severe challenges for the subsequent defrosting process. Here, we report a hierarchical surface which allows for interdroplet freezing wave propagation suppression and efficient frost removal. The enhanced performances are mainly owing to the activation of the microscale edge effect in the hierarchical surface, which increases the energy barrier for ice bridging as well as engendering the liquid lubrication during the defrosting process. We believe the concept of harnessing the surface morphology to achieve superior performances in two opposite phase transition processes might shed new light on the development of novel materials for various applications.

  3. Spring Defrosting

    NASA Technical Reports Server (NTRS)

    2005-01-01

    12 May 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows defrosting south high latitude dunes. In late winter and into the spring season, dark spots commonly form on dunes and other surfaces as seasonal carbon dioxide begins to sublime away.

    Location near: 59.3oS, 343.3oW Image width: 2 km (1.2 mi) Illumination from: upper left Season: Southern Spring

  4. Defrosting Spots

    NASA Technical Reports Server (NTRS)

    2005-01-01

    3 October 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark, defrosting spots formed on a polygon-cracked plain in the south polar region of Mars. The surface was covered with carbon dioxide frost during the previous winter. In spring, the material begins to sublime away, creating a pattern of dark spots that sometimes have wind streaks emanating from them, as wind carries away or erodes the frost.

    Location near: 87.2oS, 28.4oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  5. Defrosting Patterns

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-487, 18 September 2003

    This June 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows patterns created by defrosting processes on the south polar seasonal ice cap. Seasonal cap refers to the part of the polar cap that comes and goes with the seasons, as opposed to the residual cap, which lasts throughout the summer. The area shown here, in summer, will have no frost. This picture was taken during southern spring. As the seasonal frost begins to sublime away, dark cracks form a polygon pattern, and wind blows material to form varied bright and dark streaks. What is unknown is whether the dark streaks consist of sand and silt from beneath the seasonal frost, or whether they, too, consist of frost that has been transformed into coarse-grained particles that can be mobilized by wind. Alternatively, the streaks represent erosion and removal of frost, rather than deposition of granular material. The bright streaks are most likely made of frost--whether they are water ice or carbon dioxide ice remains to be determined. The bulk of the frosted surface shown here is carbon dioxide ice. The image is located near 87.3oS, 192.4oW. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.

  6. Defrosting, dark flow features, and dune activity on Mars: Example in Russell crater

    NASA Astrophysics Data System (ADS)

    Gardin, E.; Allemand, P.; Quantin, C.; Thollot, P.

    2010-06-01

    Defrosting processes observed on Mars are among the most unusual features described on high-resolution images. A defrosting sequence has been observed near the crest of the megadune located in the Russell crater on new high-resolution images obtained from the HiRISE instrument and on hyperspectral cubes obtained from CRISM instrument, both on board MRO. Hyperspectral images show that frost overlaps the entire megadune in middle winter. This frost is composed mainly of CO2 and of a small amount of water ice. The deepest ice signatures are mainly located near the crest of the megadune. The defrosting sequence monitored by CRISM reveals spatial heterogeneity and refrosting processes. On the morphological counterpart, the defrosting sequence starts with the development of dark spots, similar to those described in the cryptic regions. After few sols, we observe the emplacement of dark linear flow features that start from the dark spots downward of the main slope of the dune. These linear flow features are 1 to 2 m wide and 50 to 100 m long. They settle on the small rills visible on the frost cover. They are interpreted as avalanches of a mixing of sand, dust, and unstable CO2 gas released under pressure. The avalanches would be triggered by the eruption of the dark spots. The flux of material transported by the flow features has been estimated to 0.25 to 0.5 m3 by meter width each year on the megadune. This flux is larger than flux transported by wind. These dark flow features are thus very efficient to transport material on slopes located in frosted areas.

  7. Apparatus and method for evaporator defrosting

    DOEpatents

    Mei, Viung C.; Chen, Fang C.; Domitrovic, Ronald E.

    2001-01-01

    An apparatus and method for warm-liquid defrosting of the evaporator of a refrigeration system. The apparatus includes a first refrigerant expansion device that selectively expands refrigerant for cooling the evaporator, a second refrigerant expansion device that selectively expands the refrigerant after the refrigerant has passed through the evaporator, and a defrosting control for the first refrigerant expansion device and second refrigerant expansion device to selectively defrost the evaporator by causing warm refrigerant to flow through the evaporator. The apparatus is alternately embodied with a first refrigerant bypass and/or a second refrigerant bypass for selectively directing refrigerant to respectively bypass the first refrigerant expansion device and the second refrigerant expansion device, and with the defrosting control connected to the first refrigerant bypass and/or the second refrigerant bypass to selectively activate and deactivate the bypasses depending upon the current cycle of the refrigeration system. The apparatus alternately includes an accumulator for accumulating liquid and/or gaseous refrigerant that is then pumped either to a refrigerant receiver or the first refrigerant expansion device for enhanced evaporator defrosting capability. The inventive method of defrosting an evaporator in a refrigeration system includes the steps of compressing refrigerant in a compressor and cooling the refrigerant in the condenser such that the refrigerant is substantially in liquid form, passing the refrigerant substantially in liquid form through the evaporator, and expanding the refrigerant with a refrigerant expansion device after the refrigerant substantially passes through the evaporator.

  8. Defrost Temperature Termination in Supermarket Refrigeration Systems

    SciTech Connect

    Fricke, Brian A; Sharma, Vishaldeep

    2011-11-01

    The objective of this project was to determine the potential energy savings associated with implementing demand defrost strategies to defrost supermarket refrigerated display case evaporators, as compared to the widely accepted current practice of controlling display case defrost cycles with a preset timer. The defrost heater energy use of several representative display case types was evaluated. In addition, demand defrost strategies for refrigerated display cases as well as those used in residential refrigerator/freezers were evaluated. Furthermore, it is anticipated that future work will include identifying a preferred defrost strategy, with input from Retail Energy Alliance members. Based on this strategy, a demand defrost system will be designed which is suitable for supermarket refrigerated display cases. Limited field testing of the preferred defrost strategy will be performed in a supermarket environment.

  9. 9 CFR 590.539 - Defrosting operations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 40 °F.: Provided, That no portion of the defrosted liquid shall exceed 50 °F. while in or out of the container. (1) Frozen eggs packed in metal or plastic containers may be placed in running tap water (70 F° or lower) without submersion to speed defrosting. (2) The defrosted liquid shall be held at 40 °F. or...

  10. 9 CFR 590.539 - Defrosting operations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 40 °F.: Provided, That no portion of the defrosted liquid shall exceed 50 °F. while in or out of the container. (1) Frozen eggs packed in metal or plastic containers may be placed in running tap water (70 F° or lower) without submersion to speed defrosting. (2) The defrosted liquid shall be held at 40 °F. or...

  11. 64 FR 67311 - Defrost Timers From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    1999-12-01

    ... COMMISSION Defrost Timers From Japan AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the antidumping duty order on defrost timers from Japan. SUMMARY... order on defrost timers from Japan would be likely to lead to continuation or recurrence of...

  12. Defrosting South Polar Slope

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-467, 29 August 2003

    Today, August 29, 2003, Mars Global Surveyor (MGS) completes its 20,000th orbit since the start of the mapping phase of the mission in March 1999. Each of the 20,000 nearly-polar, nearly-circular orbits around the planet takes about 2 hours. The spacecraft passes over each martian polar region twelve times a day. This July 2003 MGS Mars Orbiter Camera (MOC) image shows defrosting gullies and mass movement (landslide) features in the south polar region. This is a springtime view; all of the carbon dioxide and water ice that accumulated on the ground during the previous winter is subliming away. The different physical properties of the ground beneath the frost lead to differences in the length of time that a particular surface retains frost as spring progresses. Here, the areas that still have the most frost are the bright features associated with gullies and landslide deposits. These deposits may contain more sand than their surrounding terrain--we know from images of martian sand dunes that frost tends to linger a bit later in the spring on a sandy surface. This image is located near 70.7oS, 358.2oW. The slope bearing gullies and landslide materials is facing toward the bottom/lower right. Sunlight illuminates the scene from the lower right. This image covers an area 3 km (1.9 mi) wide.

  13. Dynamic Defrosting on Scalable Superhydrophobic Surfaces

    DOE PAGES

    Murphy, Kevin R.; McClintic, William T.; Lester, Kevin C.; ...

    2017-06-27

    Recent studies have shown that frost can grow in a suspended Cassie state on nanostructured superhydrophobic surfaces. During defrosting, the melting sheet of Cassie frost spontaneously dewets into quasi-spherical slush droplets that are highly mobile. Promoting Cassie frost would therefore seem advantageous from a defrosting standpoint; however, nobody has systematically compared the efficiency of defrosting Cassie ice versus defrosting conventional surfaces. Here, we characterize the defrosting of an aluminum plate, one-half of which exhibits a superhydrophobic nanostructure while the other half is smooth and hydrophobic. For thick frost sheets (>1 mm), the superhydrophobic surface was able to dynamically shed themore » meltwater, even at very low tilt angles. In contrast, the hydrophobic surface was unable to shed any appreciable meltwater even at a 90° tilt angle. For thin frost layers (≲1 mm), not even the superhydrophobic surface could mobilize the meltwater. We attribute this to the large apparent contact angle of the meltwater, which for small amounts of frost serves to minimize coalescence events and prevent droplets from approaching the capillary length. Finally, we demonstrate a new mode of dynamic defrosting using an upside-down surface orientation, where the melting frost was able to uniformly detach from the superhydrophobic side and subsequently pull the frost from the hydrophobic side in a chain reaction. Treating surfaces to enable Cassie frost is therefore very desirable for enabling rapid and low-energy thermal defrosting, but only for frost sheets that are sufficiently thick.« less

  14. Dynamic Defrosting on Scalable Superhydrophobic Surfaces.

    PubMed

    Murphy, Kevin R; McClintic, William T; Lester, Kevin C; Collier, C Patrick; Boreyko, Jonathan B

    2017-07-19

    Recent studies have shown that frost can grow in a suspended Cassie state on nanostructured superhydrophobic surfaces. During defrosting, the melting sheet of Cassie frost spontaneously dewets into quasi-spherical slush droplets that are highly mobile. Promoting Cassie frost would therefore seem advantageous from a defrosting standpoint; however, nobody has systematically compared the efficiency of defrosting Cassie ice versus defrosting conventional surfaces. Here, we characterize the defrosting of an aluminum plate, one-half of which exhibits a superhydrophobic nanostructure while the other half is smooth and hydrophobic. For thick frost sheets (>1 mm), the superhydrophobic surface was able to dynamically shed the meltwater, even at very low tilt angles. In contrast, the hydrophobic surface was unable to shed any appreciable meltwater even at a 90° tilt angle. For thin frost layers (≲1 mm), not even the superhydrophobic surface could mobilize the meltwater. We attribute this to the large apparent contact angle of the meltwater, which for small amounts of frost serves to minimize coalescence events and prevent droplets from approaching the capillary length. Finally, we demonstrate a new mode of dynamic defrosting using an upside-down surface orientation, where the melting frost was able to uniformly detach from the superhydrophobic side and subsequently pull the frost from the hydrophobic side in a chain reaction. Treating surfaces to enable Cassie frost is therefore very desirable for enabling rapid and low-energy thermal defrosting, but only for frost sheets that are sufficiently thick.

  15. Dynamic Defrosting on Nanostructured Superhydrophobic Surfaces

    SciTech Connect

    Boreyko, Jonathan B.; Srijanto, Bernadeta R.; Nguyen, Trung Dac; Vega, Carlos; Fuentes-Cabrera, Miguel; Collier, C. Patrick

    2013-07-03

    Water suspended on chilled superhydrophobic surfaces exhibits delayed freezing; however, the interdrop growth of frost through subcooled condensate forming on the surface seems unavoidable in humid environments. It is therefore of great practical importance to determine whether facile defrosting is possible on superhydrophobic surfaces. Here in this paper, we report that nanostructured superhydrophobic surfaces promote the growth of frost in a suspended Cassie state, enabling its dynamic removal upon partial melting at low tilt angles (<15°). The dynamic removal of the melting frost occurred in two stages: spontaneous dewetting followed by gravitational mobilization. This dynamic defrosting phenomenon is driven by the low contact angle hysteresis of the defrosted meltwater relative to frost on microstructured superhydrophobic surfaces, which forms in the impaled Wenzel state. Dynamic defrosting on nanostructured superhydrophobic surfaces minimizes the time, heat, and gravitational energy required to remove frost from the surface, and is of interest for a variety of systems in cold and humid environments.

  16. MPI-Defrost: Extension of Defrost to MPI-based Cluster Environment

    NASA Astrophysics Data System (ADS)

    Amin, Mustafa A.; Easther, Richard; Finkel, Hal

    2011-06-01

    MPI-Defrost extends Frolov’s Defrost to an MPI-based cluster environment. This version has been restricted to a single field. Restoring two-field support should be straightforward, but will require some code changes. Some output options may also not be fully supported under MPI. This code was produced to support our own work, and has been made available for the benefit of anyone interested in either oscillon simulations or an MPI capable version of Defrost, and it is provided on an "as-is" basis. Andrei Frolov is the primary developer of Defrost and we thank him for placing his work under the GPL (GNU Public License), and thus allowing us to distribute this modified version.

  17. Heat pump having improved defrost system

    DOEpatents

    Chen, Fang C.; Mei, Viung C.; Murphy, Richard W.

    1998-01-01

    A heat pump system includes, in an operable relationship for transferring heat between an exterior atmosphere and an interior atmosphere via a fluid refrigerant: a compressor; an interior heat exchanger; an exterior heat exchanger; an accumulator; and means for heating the accumulator in order to defrost the exterior heat exchanger.

  18. 9 CFR 590.539 - Defrosting operations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Defrosting operations. 590.539 Section 590.539 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EGG... hours at a room temperature no higher than 40 °F. or not to exceed 24 hours at a room temperature...

  19. Heat pump having improved defrost system

    DOEpatents

    Chen, F.C.; Mei, V.C.; Murphy, R.W.

    1998-12-08

    A heat pump system includes, in an operable relationship for transferring heat between an exterior atmosphere and an interior atmosphere via a fluid refrigerant: a compressor; an interior heat exchanger; an exterior heat exchanger; an accumulator; and means for heating the accumulator in order to defrost the exterior heat exchanger. 2 figs.

  20. 9 CFR 590.539 - Defrosting operations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 590.539 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EGG PRODUCTS INSPECTION INSPECTION OF EGGS AND EGG PRODUCTS (EGG PRODUCTS INSPECTION ACT) Sanitary, Processing, and Facility Requirements § 590.539 Defrosting operations. (a) Frozen egg products which are to be...

  1. Defrosting Polar Dunes -- "The Snow Leopard"

    NASA Image and Video Library

    2000-05-16

    The patterns created by dark spots on defrosting south polar dunes are often strange and beautiful. This picture, which the Mars Orbiter Camera team has dubbed, "the snow leopard," shows a dune field located at 61.5°S, 18.9°W, as it appeared on July 1, 1999. The spots are areas where dark sand has been exposed from beneath bright frost as the south polar winter cap begins to retreat. Many of the spots have a diffuse, bright ring around them this is thought to be fresh frost that was re-precipitated after being removed from the dark spot. The spots seen on defrosting polar dunes are a new phenomenon that was not observed by previous spacecraft missions to Mars. Thus, there is much about these features that remains unknown. For example, no one yet knows why the dunes become defrosted by forming small spots that grow and grow over time. No one knows for sure if the bright rings around the dark spots are actually composed of re-precipitated frost. And no one knows for sure why some dune show spots that appear to be "lined-up" (as they do in the picture shown here). This Mars Global Surveyor Mars Orbiter Camera image is illuminated from the upper left. North is toward the upper right. The scale bar indicates a distance of 200 meters (656 feet). http://photojournal.jpl.nasa.gov/catalog/PIA02301

  2. Development of Defrost Simulation for Refrigerator

    NASA Astrophysics Data System (ADS)

    Horii, Katsunori; Shimomura, Nobuo

    In order to clarify the frost adhesion area on the inner wall of freezer compartment, defrost simulation technique for prediction the vapor change from the frost of the heat exchanger was developed. As a frost melting modeling, physical properties were only considered, and the volume and shape change of frost layer were ignored. This simulation technique was verified by the experiment under the defrost of heat exchanger by forced convection and the defrost condition of refrigerator. Calculated time variation of heat exchanger pipe surface temperature is agreed with experimental one. In addition, calculated time variation of air temperature and absolute humidity at the outlet of the heat exchanger are generally agreed with those for experiment with the progress of melting of frost. However, at the beginning of frost melting, increasing of the above mentioned calculated values is a little bit faster than those for experiment. It is considered that the difference between them is caused by not considering of changing of sectional air duct area between fins.

  3. Defrosting Polar Dunes--'The Snow Leopard'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The patterns created by dark spots on defrosting south polar dunes are often strange and beautiful. This picture, which the Mars Orbiter Camera team has dubbed, 'the snow leopard,' shows a dune field located at 61.5oS, 18.9oW, as it appeared on July 1, 1999. The spots are areas where dark sand has been exposed from beneath bright frost as the south polar winter cap begins to retreat. Many of the spots have a diffuse, bright ring around them this is thought to be fresh frost that was re-precipitated after being removed from the dark spot. The spots seen on defrosting polar dunes are a new phenomenon that was not observed by previous spacecraft missions to Mars. Thus, there is much about these features that remains unknown. For example, no one yet knows why the dunes become defrosted by forming small spots that grow and grow over time. No one knows for sure if the bright rings around the dark spots are actually composed of re-precipitated frost. And no one knows for sure why some dune show spots that appear to be 'lined-up' (as they do in the picture shown here).

    This Mars Global Surveyor Mars Orbiter Camera image is illuminated from the upper left. North is toward the upper right. The scale bar indicates a distance of 200 meters (656 feet).

    Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  4. Development of a high efficiency, automatic defrosting refrigerator-freezer

    NASA Astrophysics Data System (ADS)

    Topping, R. F.; Lee, W. D.

    The development of an energy efficient refrigerator freezer prototype to accelerate the commercialization of residential, high efficiency refrigerator freezers is described. A computer model developed to simulate the cabinet and refrigeration unit performance was used to evaluate alternative designs and optimize the cabinet insulation as well as the refrigeration component integration. Placement of polyurethane foam insulation in the cabinet and thicker insulation in the doors were used to reduce the closed door heat load of the prototype. Modifications to the evaporator system provide automatic frost-free operation with a significantly reduced defrost energy requirement. Resulting higher moisture levels in the refrigerator compartment enhance fresh food storage. A dual control system, different from most models which use only one active control, provides precise temperature regulation in both the freezer and refrigerator compartments.

  5. Development of a demand defrost controller. Final report

    SciTech Connect

    Borton, D.N.; Walker, D.H.

    1993-10-01

    The purpose of this project was to develop and commercialize a demand defrost controller that initiates defrosts of refrigeration systems only when required. The standard method of control is a time clock that usually defrosts too often, which wastes energy. The controller developed by this project uses an algorithm based on the temperature difference between the discharge and return of the display case air curtain along with several time settings to defrost only when needed. This controller was field tested in a supermarket where it controlled defrost of the low-temperature display cases. According to test results the controller could reduce annual energy consumption by 20,000 and 62,000 kWh for hot gas and electric defrost, respectively. The controller saves electric demand as well as energy, is adaptable to ambient air conditions, and provides valuable savings throughout the year. The savings are greatest for low-temperature systems that use the most energy. A less tangible benefit of the demand controller is the improvement in food quality that results from fewer defrosts.

  6. Measured impacts of supermarket humidity level on defrost performance and refrigerating system energy use

    SciTech Connect

    Henderson, H.I.; Khattar, M.

    1999-07-01

    This paper presents field-monitor data from two supermarkets where the impact of space humidity on refrigerating system energy use was evaluated. Direct digital control (DDC) systems were used at both stores to collect 15-minute monitored data. At Store A in Minneapolis, the DDC system was used to monitor system performance as well as to implement temperature-terminated control in place of time-terminated control on 16 refrigerated zones using hot gas defrost. At Store B in Indianapolis, the DDC system was used to quantify the performance trends for the single compressor rack system with electric defrost. The results at Store B showed that refrigerating system energy use decreases by nearly 10 kWh/day for each 1% drop in space relative humidity, or about 0.4% of average annual system energy use. This value includes the impact of reduced latent loads, the reduction in direct energy use and imposed load from reduced electric defrost heater operation, and the smaller imposed load from reduced anti-sweat heater energy use. The measured reductions agree well with the impact predicted using the calculation methods developed by Howell (1933b) in ASHRAE Research Project 596. At Store A, the measured data show that implementing temperature-terminated defrost reduced refrigerating system energy use by nearly 70 kWh/day over the winter period when the average space humidity was 22% RH. The savings from temperature-terminated defrost increase by 4 kWh/day per each 1% drop in relative humidity. At both stores, the same type of mechanical controls were used to duty cycle the anti-sweat heaters based on store dew point. Anti-sweat heater electricity use was observed to decrease by 4.6 kWh/day at Store B and 3.4 kWh/day at Store A for each 1% drop in relative humidity. At Store A, a more aggressive control scheme was implemented with the DDC system that reduced anti-sweat heater energy use by 7.8 kWh/day per % RH. The more aggressive control approach was reported to properly

  7. Defrosting processes on the Russell crater megadune of Mars: quantitative analysis and interpretation

    NASA Astrophysics Data System (ADS)

    Douté, S.; Wu, C.; Guo, X.; Luo, B.

    2015-10-01

    The megadune located in the Russell Crater of Mars is the siege of a complex defrosting sequence imply- ing seasonal CO2 and a small amount of water ice in each spring [3]. Besides on its pole facing slope, the dune displays gullies thought to have been carved by liquid water although they could also be related to dry avalanches triggered by the defrosting activity. In order to improve our understanding of seasonal versus secular phenomena, we conducted a quantitative analysis of a time series of joint image pairs : hyperspectral(CRISM) and high-resolution panchromatic (HiRISE),both sensors operating on board MRO. Automatic extraction and characterization of sublimation structures(e.g. dark spots) in the HiRISE images is performed on the basis of their geometry or their texture with image processing methods. The different conditions of CO2 ice are mapped by applying unsupervised linear spec- tral unmixing methods on the CRISM images. Modeling the spectral signatures with a radiative transfer model reveals the structural organization of the ice and its level of dust contamination. Finally we propose a joint interpretation of all the resulting products for understanding the defrosting processes and their role in shaping the dune.

  8. Frost sensor for use in defrost controls for refrigeration

    DOEpatents

    French, Patrick D.; Butz, James R.; Veatch, Bradley D.; O'Connor, Michael W.

    2002-01-01

    An apparatus and method for measuring the total thermal resistance to heat flow from the air to the evaporative cooler fins of a refrigeration system. The apparatus is a frost sensor that measures the reduction in heat flow due to the added thermal resistance of ice (reduced conduction) as well as the reduction in heat flow due to the blockage of airflow (reduced convection) from excessive ice formation. The sensor triggers a defrost cycle when needed, instead of on a timed interval. The invention is also a method for control of frost in a system that transfers heat from air to a refrigerant along a thermal path. The method involves measuring the thermal conductivity of the thermal path from the air to the refrigerant, recognizing a reduction in thermal conductivity due to the thermal insulation effect of the frost and due to the loss of airflow from excessive ice formation; and controlling the defrosting of the system.

  9. Dynamics of Defrosting on Hydrophobic and Superhydrophobic Surfaces

    NASA Astrophysics Data System (ADS)

    Murphy, Kevin; McClintic, William; Lester, Kevin; Collier, Patrick; Boreyko, Jonathan

    2016-11-01

    It has recently been demonstrated that frost can grow in a suspended Cassie state on nanostructured superhydrophobic surfaces, which has implications for enhanced defrosting rates. However, to date there have been no direct comparisons of the defrosting kinetics of Cassie frost versus frost on conventional surfaces. Here, we fabricate a hybrid aluminum plate where half of the top face exhibits a superhydrophobic nanostructure while the other half is smooth and hydrophobic. By growing frost to varying thicknesses and melting at several tilt angles, we reveal the advantages and disadvantages of each surface with regards to the extent and speed of the shedding of melt water. For sufficiently thick frost layers, the Cassie state of frost on the superhydrophobic surface uniquely enabled the rapid and effective shedding of melt water even at low tilt angles. On the other hand, the hydrophobic surface was more effective at removing very thin frost sheets, as the reduced contact angle of water on the surface facilitated the coalescence of droplets to grow the melt water beyond the capillary length for gravitational removal. Therefore, the utilization of superhydrophobic versus hydrophobic surfaces for defrosting applications depends upon the context of the system conditions.

  10. Evolutional schemes for objects with active nuclei

    NASA Technical Reports Server (NTRS)

    Komberg, B. V.

    1979-01-01

    The observational properties of quasistellar objects (QSO) reveal that they are extremely violent nuclei of distant galaxies, but the evolutionary stage of these galaxies is still undetermined. Various published attempts to classify QSO under different criteria - including the one based on the morphological type of the surrounding galaxy E- or S- are analyzed. There are evidences that radioactive quasars reside in E-, while radio-quiet quasars reside in both E- and S- systems. The latter may be evolutionary connected to Seyfert-like objects. A correlation between the nuclei activity level in systems of different morphological type and the relative amount of gas in them is noted. From the point of view of activity level and the duration of active stage of nuclei it is concluded that an interaction of galaxies with the intergalactic medium is of particular importance and must be most conspicuous in spheriodal systems of central regions of rich clusters, in tight groups and binary galaxies.

  11. 16 CFR Appendix A1 to Part 305 - Refrigerators With Automatic Defrost

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Refrigerators With Automatic Defrost A1 Appendix A1 to Part 305 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF...) Pt. 305, App. A1 Appendix A1 to Part 305—Refrigerators With Automatic Defrost Range...

  12. 16 CFR Appendix B1 to Part 305 - Upright Freezers With Manual Defrost

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Upright Freezers With Manual Defrost B1 Appendix B1 to Part 305 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF...) Pt. 305, App. B1 Appendix B1 to Part 305—Upright Freezers With Manual Defrost Range...

  13. A Hybrid Nonlinear Control Scheme for Active Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Xia, F.; Albritton, N. G.; Hung, J. Y.; Nelms, R. M.

    1996-01-01

    A nonlinear control scheme for active magnetic bearings is presented in this work. Magnet winding currents are chosen as control inputs for the electromechanical dynamics, which are linearized using feedback linearization. Then, the desired magnet currents are enforced by sliding mode control design of the electromagnetic dynamics. The overall control scheme is described by a multiple loop block diagram; the approach also falls in the class of nonlinear controls that are collectively known as the 'integrator backstepping' method. Control system hardware and new switching power electronics for implementing the controller are described. Various experiments and simulation results are presented to demonstrate the concepts' potentials.

  14. Defrosting of a Heat Exchanger for Precooled Turbojet Engines Using Jet Impingement

    NASA Astrophysics Data System (ADS)

    Fukiba, Katsuyoshi; Inoue, Shou; Sato, Tetsuya; Ohkubo, Hidetoshi

    An innovative defrosting method for precooled turbojet engines are presented, and validated in this study using experimental methods. High speed gas jet was impinged on the cooling tubes of a heat exchanger for the purpose of defrosting. The coolant of the heat exchanger was liquid nitrogen, and whose temperature was 83K. The air flow speed, the air temperature and the air humidity were 1.0m/s, 23ºC and 59%, respectively. The effects of the jet duration, jet intervals and humidity of the jet gas on the heat exchange were assessed. As a result, we found that the presenting defrosting method is valid for the defrosting of the precooler.

  15. Variable interval time/temperature (VITT) defrost-control-system evaluation

    SciTech Connect

    1980-08-12

    Two variable-interval-time/temperature (VITT) heat pump defrost control systems are analyzed to determine if systems manufactured by Honeywell and Ranco qualify for credit for heat pumps with demand defrost control. The operation of the systems is described. VITT controls are not demand defrost control systems but utilize demand defrost control as backup systems in most Ranco models and all Honeywell models. The evaluations and results, intended to provide DOE information in making its determinations regarding credits for the control systems are discussed. The evaluation methodology utilizes a modified version of the Heat Pump Seasonal Performance Model (HPSPM) and the important modifications are discussed in Appendix A. Appendix B contains a detailed listing and discussion of the HPSPM output. (MCW)

  16. Defrosting Polar Dunes--"They Look Like Bushes!"

    NASA Image and Video Library

    2000-05-26

    "They look like bushes!" That's what almost everyone says when they see the dark features found in pictures taken of sand dunes in the polar regions as they are beginning to defrost after a long, cold winter. It is hard to escape the fact that, at first glance, these images acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) over both polar regions during the spring and summer seasons, do indeed resemble aerial photographs of sand dune fields on Earth -- complete with vegetation growing on and around them! Of course, this is not what the features are, as we describe below and in related picture captions. Still, don't they look like vegetation to you? Shown here are two views of the same MGS MOC image. On the left is the full scene, on the right is an expanded view of a portion of the scene on the left. The bright, smooth surfaces that are dotted with occasional, nearly triangular dark spots are sand dunes covered by winter frost. The MGS MOC has been used over the past several months (April-August 1999) to monitor dark spots as they form and evolve on polar dune surfaces. The dark spots typically appear first along the lower margins of a dune -- similar to the position of bushes and tufts of grass that occur in and among some sand dunes on Earth. Because the martian air pressure is very low -- 100 times lower than at Sea Level on Earth -- ice on Mars does not melt and become liquid when it warms up. Instead, ice sublimes -- that is, it changes directly from solid to gas, just as "dry ice" does on Earth. As polar dunes emerge from the months-long winter night, and first become exposed to sunlight, the bright winter frost and snow begins to sublime. This process is not uniform everywhere on a dune, but begins in small spots and then over several months it spreads until the entire dune is spotted like a leopard. The early stages of the defrosting process -- as in the picture shown here -- give the impression that something is "growing" on the dunes

  17. Defrosting Polar Dunes--'They Look Like Bushes!'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    'They look like bushes!' That's what almost everyone says when they see the dark features found in pictures taken of sand dunes in the polar regions as they are beginning to defrost after a long, cold winter. It is hard to escape the fact that, at first glance, these images acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) over both polar regions during the spring and summer seasons, do indeed resemble aerial photographs of sand dune fields on Earth--complete with vegetation growing on and around them! Of course, this is not what the features are, as we describe below and in related picture captions. Still, don't they look like vegetation to you? Shown here are two views of the same MGS MOC image. On the left is the full scene, on the right is an expanded view of a portion of the scene on the left. The bright, smooth surfaces that are dotted with occasional, nearly triangular dark spots are sand dunes covered by winter frost.

    The MGS MOC has been used over the past several months (April-August 1999) to monitor dark spots as they form and evolve on polar dune surfaces. The dark spots typically appear first along the lower margins of a dune--similar to the position of bushes and tufts of grass that occur in and among some sand dunes on Earth.

    Because the martian air pressure is very low--100 times lower than at Sea Level on Earth--ice on Mars does not melt and become liquid when it warms up. Instead, ice sublimes--that is, it changes directly from solid to gas, just as 'dry ice' does on Earth. As polar dunes emerge from the months-long winter night, and first become exposed to sunlight, the bright winter frost and snow begins to sublime. This process is not uniform everywhere on a dune, but begins in small spots and then over several months it spreads until the entire dune is spotted like a leopard.

    The early stages of the defrosting process--as in the picture shown here--give the impression that something is 'growing' on the dunes

  18. Defrosting Polar Dunes--'They Look Like Bushes!'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    'They look like bushes!' That's what almost everyone says when they see the dark features found in pictures taken of sand dunes in the polar regions as they are beginning to defrost after a long, cold winter. It is hard to escape the fact that, at first glance, these images acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) over both polar regions during the spring and summer seasons, do indeed resemble aerial photographs of sand dune fields on Earth--complete with vegetation growing on and around them! Of course, this is not what the features are, as we describe below and in related picture captions. Still, don't they look like vegetation to you? Shown here are two views of the same MGS MOC image. On the left is the full scene, on the right is an expanded view of a portion of the scene on the left. The bright, smooth surfaces that are dotted with occasional, nearly triangular dark spots are sand dunes covered by winter frost.

    The MGS MOC has been used over the past several months (April-August 1999) to monitor dark spots as they form and evolve on polar dune surfaces. The dark spots typically appear first along the lower margins of a dune--similar to the position of bushes and tufts of grass that occur in and among some sand dunes on Earth.

    Because the martian air pressure is very low--100 times lower than at Sea Level on Earth--ice on Mars does not melt and become liquid when it warms up. Instead, ice sublimes--that is, it changes directly from solid to gas, just as 'dry ice' does on Earth. As polar dunes emerge from the months-long winter night, and first become exposed to sunlight, the bright winter frost and snow begins to sublime. This process is not uniform everywhere on a dune, but begins in small spots and then over several months it spreads until the entire dune is spotted like a leopard.

    The early stages of the defrosting process--as in the picture shown here--give the impression that something is 'growing' on the dunes

  19. Defrosting Polar Dunes--Dark Spots and Wind Streaks

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The first time that the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)team saw dark spots on defrosting dune surfaces was in August and September of 1998. At that time, it was the north polar seasonal frost cap that was subliming away (more recent images from 1999 have shown the south polar frosts). This picture (above) shows a small portion of the giant dune field that surrounds the north polar region, as it appeared on August 23, 1998. At the time, it was early northern spring and the dunes were still covered with winter frost.

    Dark spots had appeared on the north polar dunes, and many of them exhibited a radial or semi-radial pattern of dark streaks and streamers. At first, there was speculation that the streaks indicated that the defrosting process might somehow involve explosions! The dark spots seemed to resemble small craters with dark, radial ejecta. It seemed possible that frozen carbon dioxide trapped beneath water ice might somehow heat up, turn to gas, expand, and then 'explode' in either a small blast or at least a 'puff' of air similar to that which comes from the blowhole of a surfacing whale or seal.

    The image shown here changed the earlier impression. The dark spots and streaks do not result from explosions. The spots--though not well understood--represent the earliest stages of defrosting on the sand dunes. The streaks, instead of being caused by small explosions, are instead the result of wind. In this picture, the fine, dark streaks show essentially identical orientations from spot to spot (e.g., compare the spots seen in boxes (a) and (b)). Each ray of dark material must result from wind blowing from a particular direction--for example, all of the spots in this picture exhibit a ray that points toward the upper left corner of the image, and each of these rays indicates the same wind regime. Each spot also has a ray pointing toward the lower right and top/upper-right. These, too, must indicate periods when the wind was strong

  20. Defrosting Polar Dunes--Dark Spots and Wind Streaks

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The first time that the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)team saw dark spots on defrosting dune surfaces was in August and September of 1998. At that time, it was the north polar seasonal frost cap that was subliming away (more recent images from 1999 have shown the south polar frosts). This picture (above) shows a small portion of the giant dune field that surrounds the north polar region, as it appeared on August 23, 1998. At the time, it was early northern spring and the dunes were still covered with winter frost.

    Dark spots had appeared on the north polar dunes, and many of them exhibited a radial or semi-radial pattern of dark streaks and streamers. At first, there was speculation that the streaks indicated that the defrosting process might somehow involve explosions! The dark spots seemed to resemble small craters with dark, radial ejecta. It seemed possible that frozen carbon dioxide trapped beneath water ice might somehow heat up, turn to gas, expand, and then 'explode' in either a small blast or at least a 'puff' of air similar to that which comes from the blowhole of a surfacing whale or seal.

    The image shown here changed the earlier impression. The dark spots and streaks do not result from explosions. The spots--though not well understood--represent the earliest stages of defrosting on the sand dunes. The streaks, instead of being caused by small explosions, are instead the result of wind. In this picture, the fine, dark streaks show essentially identical orientations from spot to spot (e.g., compare the spots seen in boxes (a) and (b)). Each ray of dark material must result from wind blowing from a particular direction--for example, all of the spots in this picture exhibit a ray that points toward the upper left corner of the image, and each of these rays indicates the same wind regime. Each spot also has a ray pointing toward the lower right and top/upper-right. These, too, must indicate periods when the wind was strong

  1. [Quality control of defrosted cord blood units: results from an inter-laboratory study].

    PubMed

    Panterne, B; Richard, M-J; Sabatini, C; Pouthier, F; Mouillot, L; Bardey, D; Boulanger, F; Créa, S; Dal Cortivo, L; Decot, V; Fleury-Cappellesso, S; Giraud, C; Lapierre, V; Léauté, A-G; Le Berre, C; Lemarié, C; Piard, N; Rapatel, C; Rosenzwajg, M

    2010-04-01

    Today, haematopoietic stem cell graft from placental blood concerns more than 15 % of allogeneic grafts. An inter-laboratory study of the quality control of defrosted cord blood units has been coordinated by the French society for cell and tissue bioengineering (SFBCT), with the cord blood bank of Bourgogne Franche-Comté and controlled by the French health products safety agency (Afssaps). The aim of this study is to ensure the inter-laboratory reproducibility of the quality controls practised by the banks during defrosting. The cellular outputs were analyzed according to the defrosting techniques, according to the method used in flow cytometry: single-platform (SP) versus double-platform (DP), or the product nature, i.e. in total blood or miniaturized. Forty-two units of placental blood (USP), which were out of range were provided for defrosting to 14 participating sites. USP were defrosted and controlled according to the procedures of each bank. Once the USP is defrosted, a part of the product was controlled by the site and the other part by Afssaps. Following controls were carried out: numeration of the total nucleated cells (TNC) and of CD34+ cells (made by a SP method in Afssaps) and functional assay. Concerning TNC, the defrosting sites obtained a cellular output of 94 %+/-28 in day 0 compared with an output of 72 %+/-24 in Afssaps showing a rather good stability of the USP transmitted with an average deviation of 23 %+/-22. The freezing process with or without reduction of volume does not affect this variation. Concerning the numeration of CD34+ cells, the average deviation between the participating sites and Afssaps was 29 %+/-23 compared with 21 %+/-16 for the sites using a SP method against 47 %+/-25 for those using a DP method. The CD34+ outputs are equal to 82 % +/- 60 in day 0 for the participating sites against 52 %+/-20 for Afssaps. For the sites using a DP method, it is stressed that this output is particularly high with a rate of 126 %+/-90 (n=15

  2. WARM-LIQUID DEFROST FOR COMMERCIAL FOOD DISPLAY CASES: EXPERIMENTAL INVESTIGATION AT 32.2 DEGREES C CONDENSING

    EPA Science Inventory

    The paper gives results of an experimental investigation at 32.2 C condensing of warm-liquid defrost for commercial food display cases. A refrigeration test rig with two open cases and two reach-in cases was tested using warm-liquid defrost (WLD) at -34.4 C evaporating, 32.2 C co...

  3. WARM-LIQUID DEFROST FOR COMMERCIAL FOOD DISPLAY CASES: EXPERIMENTAL INVESTIGATION AT 32.2 DEGREES C CONDENSING

    EPA Science Inventory

    The paper gives results of an experimental investigation at 32.2 C condensing of warm-liquid defrost for commercial food display cases. A refrigeration test rig with two open cases and two reach-in cases was tested using warm-liquid defrost (WLD) at -34.4 C evaporating, 32.2 C co...

  4. 16 CFR Appendix A3 to Part 305 - Refrigerator-Freezers With Partial Automatic Defrost

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Refrigerator-Freezers With Partial Automatic Defrost A3 Appendix A3 to Part 305 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER... LABELING RULEâ) Pt. 305, App. A3 Appendix A3 to Part 305—Refrigerator-Freezers With Partial...

  5. 16 CFR Appendix A2 to Part 305 - Refrigerators and Refrigerators-Freezers With Manual Defrost

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Refrigerators and Refrigerators-Freezers... ACT (âAPPLIANCE LABELING RULEâ) Pt. 305, App. A2 Appendix A2 to Part 305—Refrigerators and Refrigerators-Freezers With Manual Defrost Range Information Manufacturer's Rated Total Refrigerated Volume...

  6. 16 CFR Appendix B2 to Part 305 - Upright Freezers With Automatic Defrost

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Upright Freezers With Automatic Defrost B2 Appendix B2 to Part 305 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF... (âENERGY LABELING RULEâ) Pt. 305, App. B2 Appendix B2 to Part 305—Upright Freezers With Automatic...

  7. 16 CFR Appendix A1 to Part 305 - Refrigerators With Automatic Defrost

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Refrigerators With Automatic Defrost A1 Appendix A1 to Part 305 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC ACTS OF... (âENERGY LABELING RULEâ) Pt. 305, App. A1 Appendix A1 to Part 305—Refrigerators With Automatic...

  8. Investigation of existing heat-pump defrost test data. Subtask 4.1: Consumer products minimum energy efficiency standards program

    NASA Astrophysics Data System (ADS)

    1980-10-01

    An effort to seek and identify information on performance of heat pumps with on and off cycles and performance during frost building and defrost conditions is reported. The methodology for obtaining data and information is described. Synopses of literature found to be pertinent are presented as well as the results of information sought and obtained by telephone. It is concluded that none of the data obtained is suitable for detailed comparison of the several correlating relationships for frost building and defrost data.

  9. A Novel, Simplified Scheme for Plastics Identification: "JCE" Classroom Activity 104

    ERIC Educational Resources Information Center

    Harris, Mary E.; Walker, Barbara

    2010-01-01

    In this Activity, students identify samples of seven types of recyclable plastic by using a flowchart scheme. The flowchart procedure includes making density comparisons of the plastic samples in water and alcohol and observing physical changes of plastic samples subjected to boiling water temperatures and exposure to acetone. This scheme is…

  10. A Novel, Simplified Scheme for Plastics Identification: "JCE" Classroom Activity 104

    ERIC Educational Resources Information Center

    Harris, Mary E.; Walker, Barbara

    2010-01-01

    In this Activity, students identify samples of seven types of recyclable plastic by using a flowchart scheme. The flowchart procedure includes making density comparisons of the plastic samples in water and alcohol and observing physical changes of plastic samples subjected to boiling water temperatures and exposure to acetone. This scheme is…

  11. Refrigeration loads in a freezer due to hot gas defrost and their associated costs

    SciTech Connect

    Cole, R.A. )

    1989-01-01

    The build-up of frost on unit cooler surfaces, if not periodically cleared, will eventually cause impairment of the unit's performance, eventually rendering it useless. Thus it is necessary, in spaces below freezing, to provide an external supply of heat to warm the unit sufficiently to melt the frost and remove it. In large central-plant-type systems the most common method employed for supplying heat is from the high-pressure side of the refrigeration system, referred to as hot gas defrost. Although the heat thus captured for use in melting frost would otherwise be rejected external to the system, the defrosting process is not free of cost. There are significant losses associated with the process the magnitude of which have not heretofore been fully identified. This paper looks at the heat and mass transfer and fluid flow mechanisms involved in the hot gas defrost process in large commercial freezers. It suggests some mathematical models for analysis of the phenomenon and offers nomographs for estimating the resultant refrigeration loads and associated costs.

  12. Passive and active pulse stacking scheme for pulse shaping

    DOEpatents

    Harney, Robert C.; Schipper, John F.

    1977-01-01

    Apparatus and method for producing a sequence of radiation pulses with a pulse envelope of time variation which is controllable by an external electromagnetic signal applied to an active medium or by a sectored reflector, through which the radiation passes.

  13. 16 CFR Appendix A4 to Part 305 - Refrigerator-Freezers With Automatic Defrost With Top-Mounted Freezer Without Through-the-Door...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Refrigerator-Freezers With Automatic Defrost With Top-Mounted Freezer Without Through-the-Door Ice Service A4 Appendix A4 to Part 305 Commercial...—Refrigerator-Freezers With Automatic Defrost With Top-Mounted Freezer Without Through-the-Door Ice...

  14. 16 CFR Appendix A7 to Part 305 - Refrigerator-freezers With Automatic Defrost With Top-mounted Freezer With Through-the-door Ice...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Refrigerator-freezers With Automatic Defrost With Top-mounted Freezer With Through-the-door Ice Service A7 Appendix A7 to Part 305 Commercial...—Refrigerator-freezers With Automatic Defrost With Top-mounted Freezer With Through-the-door Ice Service...

  15. 16 CFR Appendix A4 to Part 305 - Refrigerator-Freezers With Automatic Defrost With Top-Mounted Freezer Without Through-the-Door...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Refrigerator-Freezers With Automatic Defrost With Top-Mounted Freezer Without Through-the-Door Ice Service A4 Appendix A4 to Part 305 Commercial...—Refrigerator-Freezers With Automatic Defrost With Top-Mounted Freezer Without Through-the-Door Ice...

  16. 16 CFR Appendix A5 to Part 305 - Refrigerator-Freezers With Automatic Defrost With Side-Mounted Freezer Without Through-the-Door...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Refrigerator-Freezers With Automatic Defrost With Side-Mounted Freezer Without Through-the-Door Ice Service A5 Appendix A5 to Part 305 Commercial...—Refrigerator-Freezers With Automatic Defrost With Side-Mounted Freezer Without Through-the-Door Ice...

  17. 16 CFR Appendix A6 to Part 305 - Refrigerator-Freezers With Automatic Defrost With Bottom-Mounted Freezer Without Through-the-Door...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Refrigerator-Freezers With Automatic Defrost With Bottom-Mounted Freezer Without Through-the-Door Ice Service A6 Appendix A6 to Part 305 Commercial...—Refrigerator-Freezers With Automatic Defrost With Bottom-Mounted Freezer Without Through-the-Door Ice...

  18. 16 CFR Appendix A8 to Part 305 - Refrigerator-freezers With Automatic Defrost With Side-mounted Freezer With Through-the-door Ice...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Refrigerator-freezers With Automatic Defrost With Side-mounted Freezer With Through-the-door Ice Service A8 Appendix A8 to Part 305 Commercial...—Refrigerator-freezers With Automatic Defrost With Side-mounted Freezer With Through-the-door Ice Service...

  19. 16 CFR Appendix A7 to Part 305 - Refrigerator-freezers With Automatic Defrost With Top-mounted Freezer With Through-the-door Ice...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Refrigerator-freezers With Automatic Defrost With Top-mounted Freezer With Through-the-door Ice Service A7 Appendix A7 to Part 305 Commercial...—Refrigerator-freezers With Automatic Defrost With Top-mounted Freezer With Through-the-door Ice Service...

  20. 16 CFR Appendix A8 to Part 305 - Refrigerator-freezers With Automatic Defrost With Side-mounted Freezer With Through-the-door Ice...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Refrigerator-freezers With Automatic Defrost With Side-mounted Freezer With Through-the-door Ice Service A8 Appendix A8 to Part 305 Commercial...—Refrigerator-freezers With Automatic Defrost With Side-mounted Freezer With Through-the-door Ice Service...

  1. 16 CFR Appendix A5 to Part 305 - Refrigerator-Freezers With Automatic Defrost With Side-Mounted Freezer Without Through-the-Door...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Refrigerator-Freezers With Automatic Defrost With Side-Mounted Freezer Without Through-the-Door Ice Service A5 Appendix A5 to Part 305 Commercial...—Refrigerator-Freezers With Automatic Defrost With Side-Mounted Freezer Without Through-the-Door Ice...

  2. 16 CFR Appendix A6 to Part 305 - Refrigerator-Freezers With Automatic Defrost With Bottom-Mounted Freezer Without Through-the-Door...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Refrigerator-Freezers With Automatic Defrost With Bottom-Mounted Freezer Without Through-the-Door Ice Service A6 Appendix A6 to Part 305 Commercial...—Refrigerator-Freezers With Automatic Defrost With Bottom-Mounted Freezer Without Through-the-Door Ice...

  3. Gene gun administration of therapeutic HPV DNA vaccination restores the efficacy of prolonged defrosted viral based vaccine.

    PubMed

    Lin, Cheng-Tao; Yen, Chih-Feng; Shaw, Sheng-Wen; Yen, Tzu-Chen; Chen, Yin-Ju; Soong, Yung-Kuei; Lai, Chyong-Huey

    2009-12-09

    Freshly defrosted vaccines generate promising antitumor immunity by raising both robust CD8 and CD4 responses with a TC1/Th1-dominant cytokine profile. However, prolonged (overnight) defrosted Sindbis virus-E7/HSP70 priming and Vaccinia-E7/HSP70 booster in mouse model only elicited 20% long-term tumor-free survival in comparison with the fresh vaccines. The present study is to search the possible cause of its potency loss, and to evaluate the ability of pcDNA-E7/HSP70 DNA vaccination via gene gun in restoring the efficacy of E7-specific immune responses and antitumor properties. We used prolonged defrosted SINrep5-E7/HSP70 prime and defrosted Vac-E7/HSP70 boost subcutaneously, and administered intradermally cluster (3-day interval) gene gun plasmid E7-HSP70DNA vaccine twice, and evaluated its ability to generate antigen-specific cytotoxic CD8+ T-cell responses using flow cytometry as well as antitumor responses using animal positron-emission tomography (PET) imaging. The prolonged defrosted vaccines showed a significant reduction in the infectivity and a significant decrease of CD8+ and CD4+ T-cells immune responses. Administration of cluster gene gun plasmid E7-HSP70DNA twice was also found to lead to restoration of immunity that elicits a full recovery of the antitumor efficacy of the prolonged defrosted vaccines. Our study suggested that adding cluster gene gun plasmid E7-HSP70DNA vaccine twice offered a simple solution in restoring the efficacy of the prime-boost vaccination with viral vectors and has potentially significant clinical applications.

  4. Smartphone-Based Patients' Activity Recognition by Using a Self-Learning Scheme for Medical Monitoring.

    PubMed

    Guo, Junqi; Zhou, Xi; Sun, Yunchuan; Ping, Gong; Zhao, Guoxing; Li, Zhuorong

    2016-06-01

    Smartphone based activity recognition has recently received remarkable attention in various applications of mobile health such as safety monitoring, fitness tracking, and disease prediction. To achieve more accurate and simplified medical monitoring, this paper proposes a self-learning scheme for patients' activity recognition, in which a patient only needs to carry an ordinary smartphone that contains common motion sensors. After the real-time data collection though this smartphone, we preprocess the data using coordinate system transformation to eliminate phone orientation influence. A set of robust and effective features are then extracted from the preprocessed data. Because a patient may inevitably perform various unpredictable activities that have no apriori knowledge in the training dataset, we propose a self-learning activity recognition scheme. The scheme determines whether there are apriori training samples and labeled categories in training pools that well match with unpredictable activity data. If not, it automatically assembles these unpredictable samples into different clusters and gives them new category labels. These clustered samples combined with the acquired new category labels are then merged into the training dataset to reinforce recognition ability of the self-learning model. In experiments, we evaluate our scheme using the data collected from two postoperative patient volunteers, including six labeled daily activities as the initial apriori categories in the training pool. Experimental results demonstrate that the proposed self-learning scheme for activity recognition works very well for most cases. When there exist several types of unseen activities without any apriori information, the accuracy reaches above 80 % after the self-learning process converges.

  5. Multichannel feedforward control schemes with coupling compensation for active sound profiling

    NASA Astrophysics Data System (ADS)

    Mosquera-Sánchez, Jaime A.; Desmet, Wim; de Oliveira, Leopoldo P. R.

    2017-05-01

    Active sound profiling includes a number of control techniques that enables the equalization, rather than the mere reduction, of acoustic noise. Challenges may rise when trying to achieve distinct targeted sound profiles simultaneously at multiple locations, e.g., within a vehicle cabin. This paper introduces distributed multichannel control schemes for independently tailoring structural borne sound reaching a number of locations within a cavity. The proposed techniques address the cross interactions amongst feedforward active sound profiling units, which compensate for interferences of the primary sound at each location of interest by exchanging run-time data amongst the control units, while attaining the desired control targets. Computational complexity, convergence, and stability of the proposed multichannel schemes are examined in light of the physical system at which they are implemented. The tuning performance of the proposed algorithms is benchmarked with the centralized and pure-decentralized control schemes through computer simulations on a simplified numerical model, which has also been subjected to plant magnitude variations. Provided that the representation of the plant is accurate enough, the proposed multichannel control schemes have been shown as the only ones that properly deliver targeted active sound profiling tasks at each error sensor location. Experimental results in a 1:3-scaled vehicle mock-up further demonstrate that the proposed schemes are able to attain reductions of more than 60 dB upon periodic disturbances at a number of positions, while resolving cross-channel interferences. Moreover, when the sensor/actuator placement is found as defective at a given frequency, the inclusion of a regularization parameter in the cost function is seen to not hinder the proper operation of the proposed compensation schemes, at the time that it assures their stability, at the expense of losing control performance.

  6. Task discrimination from myoelectric activity: a learning scheme for EMG-based interfaces.

    PubMed

    Liarokapis, Minas V; Artemiadis, Panagiotis K; Kyriakopoulos, Kostas J

    2013-06-01

    A learning scheme based on Random Forests is used to discriminate the task to be executed using only myoelectric activity from the upper limb. Three different task features can be discriminated: subspace to move towards, object to be grasped and task to be executed (with the object). The discrimination between the different reach to grasp movements is accomplished with a random forests classifier, which is able to perform efficient features selection, helping us to reduce the number of EMG channels required for task discrimination. The proposed scheme can take advantage of both a classifier and a regressor that cooperate advantageously to split the task space, providing better estimation accuracy with task-specific EMG-based motion decoding models, as reported in [1] and [2]. The whole learning scheme can be used by a series of EMG-based interfaces, that can be found in rehabilitation cases and neural prostheses.

  7. Self-powered suspension criterion and energy regeneration implementation scheme of motor-driven active suspension

    NASA Astrophysics Data System (ADS)

    Yan, Shuai; Sun, Weichao

    2017-09-01

    Active suspension systems have advantages on mitigating the effects of vehicle vibration caused by road roughness, which are one of the most important component parts in influencing the performances of vehicles. However, high amount of energy consumption restricts the application of active suspension systems. From the point of energy saving, this paper presents a self-powered criterion of the active suspension system to judge whether a motor-driven suspension can be self-powered or not, and then a motor parameter condition is developed as a reference to design a self-powered suspension. An energy regeneration implementation scheme is subsequently proposed to make the active suspension which has the potential to be self-powered achieve energy-saving target in the real application. In this implementation scheme, operating electric circuits are designed based on different working status of the actuator and power source and it is realizable to accumulate energy from road vibration and supply energy to the actuator by switching corresponding electric circuits. To apply the self-powered suspension criterion and energy regeneration implementation scheme, an active suspension system is designed with a constrained H∞ controller and calculation results indicate that it has the capability to be self-powered. Simulation results show that the performances of the self-powered active suspension are nearly the same as those of the active suspension with an external energy source and can achieve energy regeneration at the same time.

  8. Experimental testing of a semi-active control scheme for vibration suppression

    NASA Astrophysics Data System (ADS)

    Taniwangsa, Wendy; Kelly, James M.

    1997-05-01

    An experimental investigation was performed on a semi-active control scheme that uses the rheological properties of electro-rheological fluids (ER-fluids) in squeeze-flow mode to control the dynamic behavior of single-degree-of-freedom (SDOF) systems. The reversible and very rapid changes in the mechanical properties of the fluid under variable voltage are exploited by using a control scheme that automatically turns 'on' and 'off' the electrical field as loads are applied. This control scheme rapidly adapts to any changes in the mechanical properties of the system, reducing the response of the structure for a wide range of excitation frequencies. The ER- fluid used in this study, Zeolite in silicone oil, was subjected to an electrical field range from one to five kV/mm. Tests were carried out for the 'off' system, the 'on' system, and the controlled system, and the experimental and analytical results were compared. The experimental results show that this control scheme is effective for reducing the vibration of the system. Other types of ER-fluid should be tested using this control scheme to investigate the most effective fluid for vibration suppression.

  9. Application of a micro-credit scheme to some ecological activities

    NASA Astrophysics Data System (ADS)

    Hakoyama, F.

    2017-03-01

    Micro-credit schemes are expanding very rapidly worldwide in ecological activities. Providing gas-cooking equipments in Burkina Faso is a successful example in which the micro-credit system contributes to improve not only poor women’s life but also ecological environment. In Bangladesh, a solar PV system program through micro-credit has been implemented widely and successfully: big NGOs act as equipment dealers and provide micro-credit loans to individual poor households. In contrast, there are very few cases which showed positive results in sanitation projects. Micro-credit schemes are, in principle, based on the income generated through the fund. But in usual cases, sanitation activities do not yield any income. High cost of latrine construction is another barrier. In this paper, we reviewed why we could not apply a micro-credit scheme to our “Améli-eaur project” in Burkina Faso. Common features for the success in ecological activities are 1) enough income yielded from the activity itself, 2) the strong needs from population side, and 3) established system support, both technically and administratively. If we find a way to fulfill these elements in a sanitation project, it can be a long, sustainable project.

  10. Social capital and active membership in the Ghana National Health Insurance Scheme - a mixed method study.

    PubMed

    Fenenga, Christine J; Nketiah-Amponsah, Edward; Ogink, Alice; Arhinful, Daniel K; Poortinga, Wouter; Hutter, Inge

    2015-11-02

    People's decision to enroll in a health insurance scheme is determined by socio-cultural and socio-economic factors. On request of the National health Insurance Authority (NHIA) in Ghana, our study explores the influence of social relationships on people's perceptions, behavior and decision making to enroll in the National Health Insurance Scheme. This social scheme, initiated in 2003, aims to realize accessible quality healthcare services for the entire population of Ghana. We look at relationships of trust and reciprocity between individuals in the communities (so called horizontal social capital) and between individuals and formal health institutions (called vertical social capital) in order to determine whether these two forms of social capital inhibit or facilitate enrolment of clients in the scheme. Results can support the NHIA in exploiting social capital to reach their objective and strengthen their policy and practice. We conducted 20 individual- and seven key-informant interviews, 22 focus group discussions, two stakeholder meetings and a household survey, using a random sample of 1903 households from the catchment area of 64 primary healthcare facilities. The study took place in Greater Accra Region and Western Regions in Ghana between June 2011 and March 2012. While social developments and increased heterogeneity seem to reduce community solidarity in Ghana, social networks remain common in Ghana and are valued for their multiple benefits (i.e. reciprocal trust and support, information sharing, motivation, risk sharing). Trusting relations with healthcare and insurance providers are, according healthcare clients, based on providers' clear communication, attitude, devotion, encouragement and reliability of services. Active membership of the NHIS is positive associated with community trust, trust in healthcare providers and trust in the NHIS (p-values are .009, .000 and .000 respectively). Social capital can motivate clients to enroll in health insurance

  11. A multi-modal prostate segmentation scheme by combining spectral clustering and active shape models

    NASA Astrophysics Data System (ADS)

    Toth, Robert; Tiwari, Pallavi; Rosen, Mark; Kalyanpur, Arjun; Pungavkar, Sona; Madabhushi, Anant

    2008-03-01

    Segmentation of the prostate boundary on clinical images is useful in a large number of applications including calculating prostate volume during biopsy, tumor estimation, and treatment planning. Manual segmentation of the prostate boundary is, however, time consuming and subject to inter- and intra-reader variability. Magnetic Resonance (MR) imaging (MRI) and MR Spectroscopy (MRS) have recently emerged as promising modalities for detection of prostate cancer in vivo. In this paper we present a novel scheme for accurate and automated prostate segmentation on in vivo 1.5 Tesla multi-modal MRI studies. The segmentation algorithm comprises two steps: (1) A hierarchical unsupervised spectral clustering scheme using MRS data to isolate the region of interest (ROI) corresponding to the prostate, and (2) an Active Shape Model (ASM) segmentation scheme where the ASM is initialized within the ROI obtained in the previous step. The hierarchical MRS clustering scheme in step 1 identifies spectra corresponding to locations within the prostate in an iterative fashion by discriminating between potential prostate and non-prostate spectra in a lower dimensional embedding space. The spatial locations of the prostate spectra so identified are used as the initial ROI for the ASM. The ASM is trained by identifying user-selected landmarks on the prostate boundary on T2 MRI images. Boundary points on the prostate are identified using mutual information (MI) as opposed to the traditional Mahalanobis distance, and the trained ASM is deformed to fit the boundary points so identified. Cross validation on 150 prostate MRI slices yields an average segmentation sensitivity, specificity, overlap, and positive predictive value of 89, 86, 83, and 93% respectively. We demonstrate that the accurate initialization of the ASM via the spectral clustering scheme is necessary for automated boundary extraction. Our method is fully automated, robust to system parameters, and computationally efficient.

  12. Defrosting North

    NASA Technical Reports Server (NTRS)

    2004-01-01

    15 June 2004 Spring is upon the martian northern hemisphere, and the north polar cap is shrinking. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired on 12 June 2004, shows the retreating edge of the seasonal north polar cap near 70oN, 209oW. Low clouds and fogs stream away from the cap edge as it sublimes away. North is approximately up and the image covers an area roughly 500 km (311 mi) across. Sunlight illuminates the scene from the lower left. The crater containing a thick mound of material near the right-center of the image is Korolev.

  13. The Nature of All "Inappropriate Referrals" Made to a Countywide Physical Activity Referral Scheme: Implications for Practice

    ERIC Educational Resources Information Center

    Johnston, Lynne Halley; Warwick, Jane; De Ste Croix, Mark; Crone, Diane; Sldford, Adrienne

    2005-01-01

    Objective: The aim of this study was to evaluate the impact of a centralised referral mechanism (CRM) upon the number and type of "inappropriate referrals" made to a countywide physical activity referral scheme. Design: Case study. Method: Phase 1: Hierarchical Content Analysis of 458 "inappropriate referrals" made to a countywide scheme over a…

  14. The Nature of All "Inappropriate Referrals" Made to a Countywide Physical Activity Referral Scheme: Implications for Practice

    ERIC Educational Resources Information Center

    Johnston, Lynne Halley; Warwick, Jane; De Ste Croix, Mark; Crone, Diane; Sldford, Adrienne

    2005-01-01

    Objective: The aim of this study was to evaluate the impact of a centralised referral mechanism (CRM) upon the number and type of "inappropriate referrals" made to a countywide physical activity referral scheme. Design: Case study. Method: Phase 1: Hierarchical Content Analysis of 458 "inappropriate referrals" made to a countywide scheme over a…

  15. Agent-based power sharing scheme for active hybrid power sources

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenhua

    The active hybridization technique provides an effective approach to combining the best properties of a heterogeneous set of power sources to achieve higher energy density, power density and fuel efficiency. Active hybrid power sources can be used to power hybrid electric vehicles with selected combinations of internal combustion engines, fuel cells, batteries, and/or supercapacitors. They can be deployed in all-electric ships to build a distributed electric power system. They can also be used in a bulk power system to construct an autonomous distributed energy system. An important aspect in designing an active hybrid power source is to find a suitable control strategy that can manage the active power sharing and take advantage of the inherent scalability and robustness benefits of the hybrid system. This paper presents an agent-based power sharing scheme for active hybrid power sources. To demonstrate the effectiveness of the proposed agent-based power sharing scheme, simulation studies are performed for a hybrid power source that can be used in a solar car as the main propulsion power module. Simulation results clearly indicate that the agent-based control framework is effective to coordinate the various energy sources and manage the power/voltage profiles.

  16. Bio-inspired, colorful, flexible, defrostable light-scattering hybrid films for the effective distribution of LED light.

    PubMed

    An, Seongpil; Jo, Hong Seok; Kim, Yong Il; Song, Kyo Yong; Kim, Min-Woo; Lee, Kyu Bum; Yarin, Alexander L; Yoon, Sam S

    2017-07-06

    Bioluminescent jellyfish has a unique structure derived from fiber/polymer interfaces that is advantageous for effective light scattering in the dark, deep sea water. Herein, we demonstrate the fabrication of bio-inspired hybrid films by mimicry of the jellyfish's structure, leading to excellent light-scattering performance and defrosting capability. A haze value reaching 59.3% and a heating temperature of up to 292 °C were achieved with the films. Accordingly, the developed surface constitutes an attractive optical device for lighting applications, especially for street or vehicle luminaries for freezing Arctic-climate countries. The morphological details of the hybrid films were revealed by scanning electron microscopy. The light-scattering properties of these films were examined by ultraviolet-visible-infrared spectrophotometry and anti-glare effect analyses. The defrosting performance of the hybrid films was evaluated via heating tests and infra-red observations.

  17. Active sway control of a gantry crane using hybrid input shaping and PID control schemes

    NASA Astrophysics Data System (ADS)

    Mohd Tumari, M. Z.; Shabudin, L.; Zawawi, M. A.; Shah, L. H. Ahmad

    2013-12-01

    This project presents investigations into the development of hybrid input-shaping and PID control schemes for active sway control of a gantry crane system. The application of positive input shaping involves a technique that can reduce the sway by creating a common signal that cancels its own vibration and used as a feed-forward control which is for controlling the sway angle of the pendulum, while the proportional integral derivative (PID) controller is used as a feedback control which is for controlling the crane position. The PID controller was tuned using Ziegler-Nichols method to get the best performance of the system. The hybrid input-shaping and PID control schemes guarantee a fast input tracking capability, precise payload positioning and very minimal sway motion. The modeling of gantry crane is used to simulate the system using MATLAB/SIMULINK software. The results of the response with the controllers are presented in time domains and frequency domains. The performances of control schemes are examined in terms of level of input tracking capability, sway angle reduction and time response specification.

  18. Dynamo-based scheme for forecasting the magnitude of solar activity cycles

    NASA Technical Reports Server (NTRS)

    Layden, A. C.; Fox, P. A.; Howard, J. M.; Sarajedini, A.; Schatten, K. H.

    1991-01-01

    This paper presents a general framework for forecasting the smoothed maximum level of solar activity in a given cycle, based on a simple understanding of the solar dynamo. This type of forecasting requires knowledge of the sun's polar magnetic field strength at the preceding activity minimum. Because direct measurements of this quantity are difficult to obtain, the quality of a number of proxy indicators already used by other authors is evaluated, which are physically related to the sun's polar field. These indicators are subjected to a rigorous statistical analysis, and the analysis technique for each indicator is specified in detail in order to simplify and systematize reanalysis for future use. It is found that several of these proxies are in fact poorly correlated or uncorrelated with solar activity, and thus are of little value for predicting activity maxima. Also presented is a scheme in which the predictions of the individual proxies are combined via an appropriately weighted mean to produce a compound prediction. The scheme is then applied to the current cycle 22, and a maximum smoothed international sunspot number of 171 + or - 26 is estimated.

  19. Dynamo-based scheme for forecasting the magnitude of solar activity cycles

    NASA Astrophysics Data System (ADS)

    Layden, A. C.; Fox, P. A.; Howard, J. M.; Sarajedini, A.; Schatten, K. H.

    1991-03-01

    This paper presents a general framework for forecasting the smoothed maximum level of solar activity in a given cycle, based on a simple understanding of the solar dynamo. This type of forecasting requires knowledge of the sun's polar magnetic field strength at the preceding activity minimum. Because direct measurements of this quantity are difficult to obtain, the quality of a number of proxy indicators already used by other authors is evaluated, which are physically related to the sun's polar field. These indicators are subjected to a rigorous statistical analysis, and the analysis technique for each indicator is specified in detail in order to simplify and systematize reanalysis for future use. It is found that several of these proxies are in fact poorly correlated or uncorrelated with solar activity, and thus are of little value for predicting activity maxima. Also presented is a scheme in which the predictions of the individual proxies are combined via an appropriately weighted mean to produce a compound prediction. The scheme is then applied to the current cycle 22, and a maximum smoothed international sunspot number of 171 + or - 26 is estimated.

  20. Dynamo-based scheme for forecasting the magnitude of solar activity cycles

    NASA Technical Reports Server (NTRS)

    Layden, A. C.; Fox, P. A.; Howard, J. M.; Sarajedini, A.; Schatten, K. H.

    1991-01-01

    This paper presents a general framework for forecasting the smoothed maximum level of solar activity in a given cycle, based on a simple understanding of the solar dynamo. This type of forecasting requires knowledge of the sun's polar magnetic field strength at the preceding activity minimum. Because direct measurements of this quantity are difficult to obtain, the quality of a number of proxy indicators already used by other authors is evaluated, which are physically related to the sun's polar field. These indicators are subjected to a rigorous statistical analysis, and the analysis technique for each indicator is specified in detail in order to simplify and systematize reanalysis for future use. It is found that several of these proxies are in fact poorly correlated or uncorrelated with solar activity, and thus are of little value for predicting activity maxima. Also presented is a scheme in which the predictions of the individual proxies are combined via an appropriately weighted mean to produce a compound prediction. The scheme is then applied to the current cycle 22, and a maximum smoothed international sunspot number of 171 + or - 26 is estimated.

  1. Neural encoding schemes of tactile information in afferent activity of the vibrissal system.

    PubMed

    Farfán, Fernando D; Albarracín, Ana L; Felice, Carmelo J

    2013-02-01

    When rats acquire sensory information by actively moving their vibrissae, a neural code is manifested at different levels of the sensory system. Behavioral studies in tactile discrimination agree that rats can distinguish different roughness surfaces by whisking their vibrissae. The present study explores the existence of neural encoding in the afferent activity of one vibrissal nerve. Two neural encoding schemes based on "events" were proposed (cumulative event count and median inter-event time). The events were detected by using an event detection algorithm based on multiscale decomposition of the signal (Continuous Wavelet Transform). The encoding schemes were quantitatively evaluated through the maximum amount of information which was obtained by the Shannon's mutual information formula. Moreover, the effect of difference distances between rat snout and swept surfaces on the information values was also studied. We found that roughness information was encoded by events of 0.8 ms duration in the cumulative event count and event of 1.0 to 1.6 ms duration in the median inter-event count. It was also observed that an extreme decrease of the distance between rat snout and swept surfaces significantly reduces the information values and the capacity to discriminate among the sweep situations.

  2. A novel micro-pulse laser active imaging method based on photon counting scheme

    NASA Astrophysics Data System (ADS)

    Liu, Chenghao; Yin, Wenye; Miao, Zhuang; He, Wei-ji; Chen, Qian; Gu, Guo-Hua

    2013-12-01

    We present the use and characterization of a Single Photon Detector (SPD) for active micro-pulse laser imaging. Laser active imaging technology obtains the two dimensional (2D) intensity information of objects by using the active continuous or pulsed laser illumination and an image sensor array. The Maximum range of laser active imaging is limited by the performance of image sensor, whose noise can seriously lower the obtainable SNR and degrade the quality of the reconstructed image. This paper presents a photon counting scheme based micro-pulse laser active imaging method that utilizes the SPD as the receiver and the micro-pulsed laser as the source. In this case, SPD was used to detect the laser echo. By using repeated multi-cycle detection strategies, every detected photon event is treated as an independent measurement of laser echo and thus the intensity information of objects is acquired with the response possibility estimation of laser echo. We chose a Geiger-Mode Avalanche Photodiodes (GM-APD) based approach, extending the methods of micro-pulse laser active imaging. In our implement, the number of TTL pulses output from the GM-APD within the duration of the pixel dwell time was recorder by a LabView pre-programmed instrument and then the laser echo response possibility of GM-APD was established by Full Waveform Analysis algorithm. This approach combined remote imaging with single photon sensitivity and laser active imaging.

  3. Research on the system scheme and experiment for the active laser polarization imaging

    NASA Astrophysics Data System (ADS)

    Fu, Qiang; Duan, Jin; Zhao, Rui; Li, Zheng; Zhang, Su; Zhan, Juntong; Zhu, Yong; Jiang, Hui-Lin

    2015-10-01

    The polarization imaging detection technology increased the polarization information on the basis of the intensity imaging, which is extensive application in the military and civil and other fields. The research present and development trend of polarization imaging detection technology was introduce, the system scheme of the active polarization imaging detection was put forward, and the key technologies such as the polarization information detection, optical system design, polarization radiation calibration and image fusion approach was analyzed. On this basis, detection system by existing equipment of laboratory was set up, and on the different materials such as wood, metal, plastic and goal was detected by polarization imaging to realize the active polarization imaging detection. The results show that image contrast of the metal and man-made objects is higher, the polarization effect is better, which provided the basis on the better performance of the polarization imaging instruments.

  4. Defrosting the digital library: bibliographic tools for the next generation web.

    PubMed

    Hull, Duncan; Pettifer, Steve R; Kell, Douglas B

    2008-10-01

    Many scientists now manage the bulk of their bibliographic information electronically, thereby organizing their publications and citation material from digital libraries. However, a library has been described as "thought in cold storage," and unfortunately many digital libraries can be cold, impersonal, isolated, and inaccessible places. In this Review, we discuss the current chilly state of digital libraries for the computational biologist, including PubMed, IEEE Xplore, the ACM digital library, ISI Web of Knowledge, Scopus, Citeseer, arXiv, DBLP, and Google Scholar. We illustrate the current process of using these libraries with a typical workflow, and highlight problems with managing data and metadata using URIs. We then examine a range of new applications such as Zotero, Mendeley, Mekentosj Papers, MyNCBI, CiteULike, Connotea, and HubMed that exploit the Web to make these digital libraries more personal, sociable, integrated, and accessible places. We conclude with how these applications may begin to help achieve a digital defrost, and discuss some of the issues that will help or hinder this in terms of making libraries on the Web warmer places in the future, becoming resources that are considerably more useful to both humans and machines.

  5. Defrosting the Digital Library: Bibliographic Tools for the Next Generation Web

    PubMed Central

    Hull, Duncan; Pettifer, Steve R.; Kell, Douglas B.

    2008-01-01

    Many scientists now manage the bulk of their bibliographic information electronically, thereby organizing their publications and citation material from digital libraries. However, a library has been described as “thought in cold storage,” and unfortunately many digital libraries can be cold, impersonal, isolated, and inaccessible places. In this Review, we discuss the current chilly state of digital libraries for the computational biologist, including PubMed, IEEE Xplore, the ACM digital library, ISI Web of Knowledge, Scopus, Citeseer, arXiv, DBLP, and Google Scholar. We illustrate the current process of using these libraries with a typical workflow, and highlight problems with managing data and metadata using URIs. We then examine a range of new applications such as Zotero, Mendeley, Mekentosj Papers, MyNCBI, CiteULike, Connotea, and HubMed that exploit the Web to make these digital libraries more personal, sociable, integrated, and accessible places. We conclude with how these applications may begin to help achieve a digital defrost, and discuss some of the issues that will help or hinder this in terms of making libraries on the Web warmer places in the future, becoming resources that are considerably more useful to both humans and machines. PMID:18974831

  6. Performance Analysis of Positive-feedback-based Active Anti-islanding Schemes for Inverter-Based Distributed Generators

    SciTech Connect

    Du, Pengwei; Aponte, Erick E.; Nelson, J. Keith

    2010-06-14

    Recently proposed positive-feedback-based anti-islanding schemes (AI) are highly effective in preventing islanding without causing any degradation in power quality. This paper aims to analyze the performance of these schemes quantitatively in the context of the dynamic models of inverter-based distributed generators (DG). In this study, the characteristics of these active anti-islanding methods are discussed and design guidelines are derived.

  7. The destructive negative binomial cure rate model with a latent activation scheme.

    PubMed

    Cancho, Vicente G; Bandyopadhyay, Dipankar; Louzada, Francisco; Yiqi, Bao

    2013-07-01

    A new flexible cure rate survival model is developed where the initial number of competing causes of the event of interest (say lesions or altered cells) follow a compound negative binomial (NB) distribution. This model provides a realistic interpretation of the biological mechanism of the event of interest as it models a destructive process of the initial competing risk factors and records only the damaged portion of the original number of risk factors. Besides, it also accounts for the underlying mechanisms that leads to cure through various latent activation schemes. Our method of estimation exploits maximum likelihood (ML) tools. The methodology is illustrated on a real data set on malignant melanoma, and the finite sample behavior of parameter estimates are explored through simulation studies.

  8. The destructive negative binomial cure rate model with a latent activation scheme

    PubMed Central

    Cancho, Vicente G.; Bandyopadhyay, Dipankar; Louzada, Francisco; Yiqi, Bao

    2013-01-01

    A new flexible cure rate survival model is developed where the initial number of competing causes of the event of interest (say lesions or altered cells) follow a compound negative binomial (NB) distribution. This model provides a realistic interpretation of the biological mechanism of the event of interest as it models a destructive process of the initial competing risk factors and records only the damaged portion of the original number of risk factors. Besides, it also accounts for the underlying mechanisms that leads to cure through various latent activation schemes. Our method of estimation exploits maximum likelihood (ML) tools. The methodology is illustrated on a real data set on malignant melanoma, and the finite sample behavior of parameter estimates are explored through simulation studies. PMID:23585760

  9. Influence of laterotrusive occlusal scheme on bilateral masseter EMG activity during clenching and grinding.

    PubMed

    Campillo, María José; Miralles, Rodolfo; Santander, Hugo; Valenzuela, Saúl; Fresno, María Javiera; Fuentes, Aler; Zúñiga, Claudia

    2008-10-01

    This study was designed to determine the effect of the occlusal scheme on masseter EMG activity at different jaw posture tasks. The sample included 30 healthy subjects with natural dentition and bilateral molar support, 15 with bilateral canine guidance, and 15 with bilateral group function. An inclusion criterion was that subjects had to be free of signs and symptoms of any dysfunction of the masticatory system. Bipolar surface electrodes were located on the left and right masseter muscles. EMG activity was recorded during the following jaw posture tasks: A. maximal clenching in the intercuspal position; B. grinding from intercuspal position to edge-to-edge lateral contact position; C. maximal clenching in the edge-to-edge lateral contact position; D. grinding from edge-to-edge lateral contact position to intercuspal position. EMG activity in tasks B, C, and D was lower than in task A (mixed model with unstructured covariance matrix). EMG activity was not significantly different with canine guidance or group function. EMG activity recorded on the nonworking side was higher than the working side during task C, and no different between tasks B or D. On the nonworking side, EMG activity in task B was significantly lower than C and D, and similar between task C and D. On the working side, EMG activity was significantly higher in task D than C and B, and in task B significantly higher than task C. The EMG patterns observed could be of clinical importance in the presence of parafunctional habits, i.e., clenching and/or grinding.

  10. Rural health prepayment schemes in China: towards a more active role for government.

    PubMed

    Bloom, G; Shenglan, T

    1999-04-01

    A large majority of China's rural population were members of health prepayment schemes in the 1970's. Most of these schemes collapsed during the transition to a market economy. Some localities subsequently reestablished schemes. In early 1997 a new government policy identified health prepayment as a major potential source of rural health finance. This paper draws on the experience of existing schemes to explore how government can support implementation of this policy. The decision to support the establishment of health prepayment schemes is part of the government's effort to establish new sources of finance for social services. It believes that individuals are more likely to accept voluntary contributions to a prepayment scheme than tax increases. The voluntary nature of the contributions limits the possibilities for risk-sharing and redistribution between rich and poor. This underlines the need for the government to fund a substantial share of health expenditure out of general revenues, particularly in poor localities. The paper notes that many successful prepayment schemes depend on close supervision by local political leaders. It argues that the national programme will have to translate these measures into a regulatory system which defines the responsibilities of scheme management bodies and local governments. A number of prepayment schemes have collapsed because members did not feel they got value for money. Local health bureaux will have to cooperate with prepayment schemes to ensure that health facilities provide good quality services at a reasonable cost. Users' representatives can also monitor performance. The paper concludes that government needs to clarify the relationship between health prepayment schemes and other actors in rural localities in order to increase the chance that schemes will become a major source rural health finance.

  11. [Active management of the third stage of labor: Three schemes of oxytocin: randomised clinical trial].

    PubMed

    Neri-Mejía, M; Pedraza-Avilés, A G

    2016-05-01

    To compare the effectiveness of intramuscular oxytocin against intravenous oxytocin against intravenous traditional oxytocin infusion, in the active management of the third period of the delayed impingement labor work and controlled cord traction. Randomized controlled blinded clinical trial. In women age 14 to 40 with full term pregnancy, childbirth attended by ISSSTE's Regional Hospital "Gral. Ignacio Zaragoza", in the period from August to December 2015. 152 deliveries were attended, from which 66 fulfill with selection criteria. Group 1 = 22 patients, group 2 = 21 patients and Group 3 = 23 patients. The total age average was 26.92 + 5.8. For blood volume, statistical differences were significant among the three groups (p = 0.000). Adverse reactions were presented in 1 .5%, without difference between the groups. (P = 0.337). The differences in hemoglobin values and final and initial hematocrit presented differences with statistical significance (p = 0.000 for both). Nonetheless, the differences obtained in the analysis of the diverse variables among the three types of treatment, the three schemes are effective on the obstetrical hemorrhage prevention.

  12. 16 CFR Appendix A5 to Part 305 - Refrigerator-Freezers With Automatic Defrost With Side-Mounted Freezer Without Through-the-Door...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Refrigerator-Freezers With Automatic Defrost With Side-Mounted Freezer Without Through-the-Door Ice Service A5 Appendix A5 to Part 305 Commercial... Without Through-the-Door Ice Service Range Information Manufacturer's Rated Total Refrigerated Volume in...

  13. 16 CFR Appendix A8 to Part 305 - Refrigerator-freezers With Automatic Defrost With Side-mounted Freezer With Through-the-door Ice...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Refrigerator-freezers With Automatic Defrost With Side-mounted Freezer With Through-the-door Ice Service A8 Appendix A8 to Part 305 Commercial... With Through-the-door Ice Service Range Information Manufacturer's Rated Total Refrigerated Volume in...

  14. 16 CFR Appendix A6 to Part 305 - Refrigerator-Freezers With Automatic Defrost With Bottom-Mounted Freezer Without Through-the-Door...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Refrigerator-Freezers With Automatic Defrost With Bottom-Mounted Freezer Without Through-the-Door Ice Service A6 Appendix A6 to Part 305 Commercial... Freezer Without Through-the-Door Ice Service Range Information Manufacturer's Rated Total Refrigerated...

  15. 16 CFR Appendix A4 to Part 305 - Refrigerator-Freezers With Automatic Defrost With Top-Mounted Freezer Without Through-the-Door...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Refrigerator-Freezers With Automatic Defrost With Top-Mounted Freezer Without Through-the-Door Ice Service A4 Appendix A4 to Part 305 Commercial... Without Through-the-Door Ice Service Range Information Manufacturer's Rated Total Refrigerated Volume in...

  16. 16 CFR Appendix A7 to Part 305 - Refrigerator-freezers With Automatic Defrost With Top-mounted Freezer With Through-the-door Ice...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Refrigerator-freezers With Automatic Defrost With Top-mounted Freezer With Through-the-door Ice Service A7 Appendix A7 to Part 305 Commercial... With Through-the-door Ice Service Range Information Manufacturer's Rated Total Refrigerated Volume in...

  17. Models of the Optical/Ultraviolet Continuum Polarization in Active Galactic Nuclei: Implications for Unification Schemes

    NASA Astrophysics Data System (ADS)

    Kartje, John F.

    1995-10-01

    I have computed the 1200-8000 A thermal continuum polarization induced by gas and dust arranged in configurations compatible with current active galactic nuclei (AGNs) unification schemes. Both uniform- density tori and stratified-density disk-driven winds were considered. A Monte Carlo radiative transfer code was developed which includes the polarization mechanisms of electron and dust scattering as well as dichroic extinction by aligned grains. A Galactic-type grain population was assumed. Based on these calculations, I propose a new interpretation of many of the observed polarization traits of Seyfert galaxies and QSOs: namely, that the polarization in these sources is induced by the same optically thick material which is assumed to obscure the central engine in unification schemes. In particular, I suggest that stratified-density winds could provide a natural explanation (and one consistent with unification models) of the polarization trends observed in Seyfert galaxies. Such winds can display polarizations (P ≲ 20%) oriented perpendicular to the axis along viewing angles inclined to the axis by θ0 ≳ 45° in well-collimated winds, this polarization shifts to smaller magnitudes (P ≲ 2%) and parallel orientations for more face-on viewing, consistent with the patterns observed in Seyfert 2 and Seyfert 1 sources, respectively. In less-collimated winds, scattering alone tends to produce parallel orientations for all viewing angles; perpendicular polarization at large θ0 can result if there is a high degree of magnetic grain alignment. The simplest torus models (i.e., uniform-density, opaque gas and dust) do not reproduce this flip in polarization position angle. Furthermore, they generally display high polarization magnitudes (P ≳ 10%) along most viewing angles θ0 > θ∞ (where θ is the torus half-opening angle) and negligible polarization along θ0 > θ∞. Unlike previous models for AGN polarization which invoke scattering by optically thin electron

  18. Active defense scheme against DDoS based on mobile agent and network control in network confrontation

    NASA Astrophysics Data System (ADS)

    Luo, Rong; Li, Junshan; Ye, Xia; Wang, Rui

    2013-03-01

    In order to effective defend DDoS attacks in network confrontation, an active defense scheme against DDoS is built based on Mobile Agent and network control. A distributed collaborative active defense model is constructed by using mobile agent technology and encapsulating a variety of DDoS defense techniques. Meanwhile the network control theory is applied to establish a network confrontation's control model for DDoS to control the active defense process. It provides a new idea to solve the DDoS problem.

  19. Occurrence of pharmaceutically active and non-steroidal estrogenic compounds in three different wastewater recycling schemes in Australia.

    PubMed

    Al-Rifai, Jawad H; Gabelish, Candace L; Schäfer, Andrea I

    2007-10-01

    The discovery that natural and synthetic chemicals, in the form of excreted hormones and pharmaceuticals, as well as a vast array of compounds with domestic and industrial applications, can enter the environment via wastewater treatment plants and cause a wide variety of environmental and health problems even at very low concentrations, suggests the need for improvement of water recycling. Three Australian wastewater recycling schemes, two of which employ reverse osmosis (RO) technology, the other applying ozonation and biological activated carbon filtration, have been studied for their ability to remove trace organic contaminants including 11 pharmaceutically active compounds and two non-steroidal estrogenic compounds. Contaminant concentrations were determined using a sensitive analytical method comprising solid phase extraction, derivatization and GC with MS using selected ion monitoring. In raw wastewater, concentrations of analgesics and non-steroidal anti-inflammatory medications were comparable to those found in wastewaters around the world. Remarkably, removal efficiencies for the three schemes were superior to literature values and RO was responsible for the greatest proportion of contaminant removal. The ability of RO membranes to concentrate many of the compounds was demonstrated and highlights the need for continued research into monitoring wastewater treatment, concentrate disposal, improved water recycling schemes and ultimately, safer water and a cleaner environment.

  20. Cometary cores with multiple structure from the oort cloud and the general scheme of origin of unusually active comets

    SciTech Connect

    Davydov, V.D.

    1986-03-01

    A newly conceived scheme is constructed which synthesizes consistent solutions to several principal problems concerning multiple-core comets: a power mechanism, a place and epoch of formation of the multiple core structure, the qualitative differences between current structure and younger structure, the origin of two types of cometary orbits, and a trigger mechanism for recent ignition of cometary activity of a multiple core. This scheme uses a new explanation of the ejection of dust (including icy dust) from various cometary cores as evidence that the material of multiple-core comets may be collisionally ablated at the expense of the comet-centered orbital energy of a multitude of massive boulders (see Kosm. Issled., No. 6 (1984)). Natural mechanisms are shown which preserve this important feature of multiple cores. The concept consists of the following elements: evolution of a system of satellites of the core toward a colli sionless structure; preservation of internal kinetic energy in the collisionless system over astro nomically lengthy time scales; tidal initiation of a collisional mechanism with the first revolution of the ancient multiple core in the zone of visibility. It is possible that such revoltions correspond to the existence of especially active comets in nearly parabolic orbits. Multiple structure in the core of active short-period comets might be descended from a nearly parabolic comet (if the theory holds on perturbational multistage transformation of near-parabolic orbits into contemporary short-period orbits).

  1. Source Driver Channel Reduction Schemes Employing Corresponding Pixel Alignments for Current Programming Active-Matrix Organic Light-Emitting Diode Displays

    NASA Astrophysics Data System (ADS)

    Hong, Soon-Kwang; Oh, Du-Hwan; Jeong, Seok-Hee; Park, Young-Ju; Kim, Byeong-Koo; Ha, Yong-Min; Jang, Jin

    2008-03-01

    We propose two types of novel scheme for reducing the number of output channels of driver-integrated circuit (D-IC) for the current programming compensation pixel structures of active-matrix organic light-emitting diodes (AMOLEDs). One is a 2:1 data demultiplexing technique that can reduce the number of output channels of D-IC by half. The proposed second scheme is a vertically aligned red (R), green (G), and blue (B) subpixel scheme instead of a horizontally aligned R-G-B subpixel one, which is regarded as the conventional pixel alignment scheme. We have also successfully implemented these schemes in a 2.4-in.-sized QCIF + (176 × RGB × 220) AMOLED using p-type excimer laser annealing (ELA) low-temperature polycrystalline silicon (LTPS) technology and evaluated key performance characteristics.

  2. Active control for drag reduction in turbulent channel flow: the opposition control schemes revisited

    NASA Astrophysics Data System (ADS)

    Wang, Yin-Shan; Huang, Wei-Xi; Xu, Chun-Xiao

    2016-10-01

    The opposition control schemes first proposed by Choi et al (1994 J. Fluid Mech. 262 75) employing wall-normal (v) and spanwise (w) velocity are revisited in the present study by performing direct numerical simulation to turbulent channel flow at R{e}τ = 180. Special attention is paid to the combined control, in which the wall-normal and spanwise velocities are imposed at the wall just instantaneously opposite to those at a small distance to the wall. In comparison to the v- and w-controls, combined-control could achieve the best drag reduction rate and control efficiency, with the greatest suppression of turbulence intensities. The influence of control on the statistical properties of vortices is scrutinized. By control, the numbers of vortices with every circulation and radius apparently decrease at the same normal location near the wall, while the vortex radius scaled by the actual wall-friction velocity almost remains the same. The streamwise vortices and the induced Reynolds shear stress undergo the greatest suppression by combined control. It is shown that combined control achieves a better efficacy, attributed to the co-work of the mechanisms of the v- and w-controls. At a higher Reynolds number R{e}τ = 1000, combined control is also more effective than v- and w-controls. The better suppression effect on the outer large scales is the primary reason for the larger drag reduction rate in combined control.

  3. Less noise, more activation: Multiband acquisition schemes for auditory functional MRI.

    PubMed

    De Martino, Federico; Moerel, Michelle; Ugurbil, Kamil; Formisano, Elia; Yacoub, Essa

    2015-08-01

    To improve acquisition in fMRI studies of audition by using multiband (MB) gradient-echo echo planar imaging (GE-EPI). Data were acquired at 3T (Siemens Skyra) with a 32-channel head coil. Functional responses were obtained by presenting stimuli [tones and natural sounds (voices, speech, music, tools, animal cries)] in silent gaps between image acquisitions. Two-fold slice acceleration (MB2) was compared with a standard GE-EPI (MB1). Coverage and sampling rate (TR = 3 s) were kept constant across acquisition schemes. The longer gap in MB2 scans was used to present: (i) sounds of the same length as in conventional GE-EPI (type 1; 800 ms stimuli); (ii) sounds of double the length (type 2; 1600 ms stimuli). Functional responses to all sounds (i.e., main effect) were stronger when acquired with slice acceleration (i.e., shorter acquisition time). The difference between voice and nonvoice responses was greater in MB2 type 1 acquisitions (i.e., same length sounds as GE-EPI but presented in a longer silent gap) than in standard GE-EPI acquisitions (interaction effect). Reducing the length of the scanner noise results in stronger functional responses. Longer "silent" periods (i.e., keeping the sound length the same as in standard acquisitions) result in stronger response to voice compared with nonvoice stimuli. © 2014 Wiley Periodicals, Inc.

  4. Automated segmentation of the quadratus lumborum muscle from magnetic resonance images using a hybrid atlas based - geodesic active contour scheme.

    PubMed

    Jurcak, V; Fripp, J; Engstrom, C; Walker, D; Salvado, O; Ourselin, S; Crozier, S

    2008-01-01

    This study presents a novel method for the automatic segmentation of the quadratus lumborum (QL) muscle from axial magnetic resonance (MR) images using a hybrid scheme incorporating the use of non-rigid registration with probabilistic atlases (PAs) and geodesic active contours (GACs). The scheme was evaluated on an MR database of 7mm axial images of the lumbar spine from 20 subjects (fast bowlers and athletic controls). This scheme involved several steps, including (i) image pre-processing, (ii) generation of PAs for the QL, psoas (PS) and erector spinae+multifidus (ES+MT) muscles and (iii) segmentation, using 3D GACs initialized and constrained by the propagation of the PAs using non-rigid registration. Pre-processing of the images involved bias field correction based on local entropy minimization with a bicubic spline model and a reverse diffusion interpolation algorithm to increase the slice resolution to 0.98 x 0.98 x 1.75mm. The processed images were then registered (affine and non-rigid) and used to generate an average atlas. The PAs for the QL, PS and ES+MT were then generated by propagation of manual segmentations. These atlases were further analysed with specialised filtering to constrain the QL segmentation from adjacent non-muscle tissues (kidney, fat). This information was then used in 3D GACs to obtain the final segmentation of the QL. The automatic segmentation results were compared with the manual segmentations using the Dice similarity metric (DSC), with a median DSC for the right and left QL muscles of 0.78 (mean = 0.77, sd=0.07) and 0.75 (mean =0.74, sd=0.07), respectively.

  5. Laboratory determination of frosting and defrosting losses for a high-efficiency air-source heat pump

    SciTech Connect

    Miller, W.A.; Ellison, R.D.

    1981-01-01

    Tests were performed to detail system and component performance data, to quantify the dynamic losses, and to seek and evaluate methods for reducing these losses. A high efficiency split-system heat pump was installed in two separate air loops, with one loop housing the indoor unit and the other housing the outdoor unit. Calculations of the heat pump's performance based on air-side measurements were within 3% of that based on refrigerant side measurements. Refrigerant flow rate was measured using a turbine flow meter. Refrigerant temperatures and pressures were measured with thermocouples and pressure transducers connected at various strategic locations in the refrigeration circuit. Electric power consumption for all motors was measured with Thermal-watt converters. Performance of the heat pump was measured under steady-state, dehumidification, and frosting-defrosting conditions with major emphasis placed on the dynamic frosting operation of the system. The study encompassed an evaluation of the system and component performance for ambient temperature levels of 8.3, 4.4, 1.7, -1.1 and -8.3/sup 0/C and for discrete humidity levels ranging from 50 to 90%.

  6. Construction of Z-scheme Ag2CO3/N-doped graphene photocatalysts with enhanced visible-light photocatalytic activity by tuning the nitrogen species

    NASA Astrophysics Data System (ADS)

    Song, Shaoqing; Meng, Aiyun; Jiang, Shujuan; Cheng, Bei; Jiang, Chuanjia

    2017-02-01

    Semiconductor-based photocatalysis has great potential in various environmental and energy applications, and Z-scheme photocatalysts have many advantages over single-component photocatalysts. The construction of a highly efficient Z-scheme photocatalytic system depends on the geometric structure arrangement, microscopic and crystalline form of the stoichiometric species, and it has not been elucidated whether the Z-scheme photocatalysts can be designed by tuning the electronic structures of cocatalysts alone. Here, using N-doped graphene (NG) as cocatalyst, we successfully constructed Z-scheme Ag2CO3-NG photocatalysts with enhanced activity for the photooxidative degradation of phenol pollutant. It was found that the pyridinic nitrogen species (Np) of NG could spontaneously reduce Ag+ to produce plasmonic Ag nanoparticles on Ag2CO3-NG, while the efficiency of the photogenerated charge separation, Z-scheme transfer option, and O2 adsorption were promoted by the graphitic nitrogen species (Ng). Therefore, the as-designed Z-scheme Ag2CO3-NG photocatalysts showed much higher activity than Ag2CO3 and its composites with graphene oxide (GO) or reduced GO as cocatalysts in the photocatalytic degradation of phenol. Hence, our results provide a new strategy for exploring advanced Z-scheme photocatalysts with NG as cocatalyst by rationally tuning the Np and Ng species.

  7. Triplet Tuning - a New ``BLACK-BOX'' Computational Scheme for Photochemically Active Molecules

    NASA Astrophysics Data System (ADS)

    Lin, Zhou; Van Voorhis, Troy

    2017-06-01

    Density functional theory (DFT) is an efficient computational tool that plays an indispensable role in the design and screening of π-conjugated organic molecules with photochemical significance. However, due to intrinsic problems in DFT such as self-interaction error, the accurate prediction of energy levels is still a challenging task. Functionals can be parameterized to correct these problems, but the parameters that make a well-behaved functional are system-dependent rather than universal in most cases. To alleviate both problems, optimally tuned range-separated hybrid functionals were introduced, in which the range-separation parameter, ω, can be adjusted to impose Koopman's theorem, ɛ_{HOMO} = -I. These functionals turned out to be good estimators for asymptotic properties like ɛ_{HOMO} and ɛ_{LUMO}. In the present study, we propose a ``black-box'' procedure that allows an automatic construction of molecule-specific range-separated hybrid functionals following the idea of such optimal tuning. However, instead of focusing on ɛ_{HOMO} and ɛ_{LUMO}, we target more local, photochemistry-relevant energy levels such as the lowest triplet state, T_1. In practice, we minimize the difference between two E_{{T}_1}'s that are obtained from two DFT-based approaches, Δ-SCF and linear-response TDDFT. We achieve this minimization using a non-empirical adjustment of two parameters in the range-separated hybrid functional - ω, and the percentage of Hartree-Fock contribution in the short-range exchange, c_{HF}. We apply this triplet tuning scheme to a variety of organic molecules with important photochemical applications, including laser dyes, photovoltaics, and light-emitting diodes, and achieved good agreements with the spectroscopic measurements for E_{{T}_1}'s and related local properties. A. Dreuw and M. Head-Gordon, Chem. Rev. 105, 4009 (2015). O. A. Vydrov and G. E. Scuseria, J. Chem. Phys. 125, 234109 (2006). L. Kronik, T. Stein, S. Refaely-Abramson, and R

  8. Physical activity on prescription schemes (PARS): do programme characteristics influence effectiveness? Results of a systematic review and meta-analyses

    PubMed Central

    Arsenijevic, Jelena; Groot, Wim

    2017-01-01

    Background Physical activity on prescription schemes (PARS) are health promotion programmes that have been implemented in various countries. The aim of this study was to outline the differences in the design of PARS in different countries. This study also explored the differences in the adherence rate to PARS and the self-reported level of physical activity between PARS users in different countries. Method A systematic literature review and meta-analyses were conducted. We searched PubMed and EBASCO in July 2015 and updated our search in September 2015. Studies that reported adherence to the programme and self-reported level of physical activity, published in the English language in a peer-reviewed journal since 2000, were included. The difference in the pooled adherence rate after finishing the PARS programme and the adherence rate before or during the PARS programme was 17% (95% CI 9% to 24%). The difference in the pooled physical activity was 0.93 unit score (95 CI −3.57 to 1.71). For the adherence rate, a meta-regression was conducted. Results In total, 37 studies conducted in 11 different countries met the inclusion criteria. Among them, 31 reported the adherence rate, while the level of physical activity was reported in 17 studies. Results from meta-analyses show that PARS had an effect on the adherence rate of physical activity, while the results from the meta-regressions show that programme characteristics such as type of chronic disease and the follow-up period influenced the adherence rate. Conclusions The effects of PARS on adherence and self-reported physical activity were influenced by programme characteristics and also by the design of the study. Future studies on the effectiveness of PARS should use a prospective longitudinal design and combine quantitative and qualitative data. Furthermore, future evaluation studies should distinguish between evaluating the adherence rate and the self-reported physical activity among participants with different

  9. A network-based multi-target computational estimation scheme for anticoagulant activities of compounds.

    PubMed

    Li, Qian; Li, Xudong; Li, Canghai; Chen, Lirong; Song, Jun; Tang, Yalin; Xu, Xiaojie

    2011-03-22

    Traditional virtual screening method pays more attention on predicted binding affinity between drug molecule and target related to a certain disease instead of phenotypic data of drug molecule against disease system, as is often less effective on discovery of the drug which is used to treat many types of complex diseases. Virtual screening against a complex disease by general network estimation has become feasible with the development of network biology and system biology. More effective methods of computational estimation for the whole efficacy of a compound in a complex disease system are needed, given the distinct weightiness of the different target in a biological process and the standpoint that partial inhibition of several targets can be more efficient than the complete inhibition of a single target. We developed a novel approach by integrating the affinity predictions from multi-target docking studies with biological network efficiency analysis to estimate the anticoagulant activities of compounds. From results of network efficiency calculation for human clotting cascade, factor Xa and thrombin were identified as the two most fragile enzymes, while the catalytic reaction mediated by complex IXa:VIIIa and the formation of the complex VIIIa:IXa were recognized as the two most fragile biological matter in the human clotting cascade system. Furthermore, the method which combined network efficiency with molecular docking scores was applied to estimate the anticoagulant activities of a serial of argatroban intermediates and eight natural products respectively. The better correlation (r = 0.671) between the experimental data and the decrease of the network deficiency suggests that the approach could be a promising computational systems biology tool to aid identification of anticoagulant activities of compounds in drug discovery. This article proposes a network-based multi-target computational estimation method for anticoagulant activities of compounds by

  10. Integrating puffing and explosions in a general scheme for Strombolian-style activity

    NASA Astrophysics Data System (ADS)

    Gaudin, Damien; Taddeucci, Jacopo; Scarlato, Piergiorgio; del Bello, Elisabetta; Ricci, Tullio; Orr, Tim; Houghton, Bruce; Harris, Andrew; Rao, Sandro; Bucci, Augusto

    2017-03-01

    Strombolian eruptions are among the most common subaerial styles of explosive volcanism worldwide. Distinctive features of each volcano lead to a correspondingly wide range of variations of magnitude and erupted products, but most papers focus on a single type of event at a single volcano. Here, in order to emphasize the common features underlying this diversity of styles, we scrutinize a database from 35 different erupting vents, including 21 thermal infrared videos from Stromboli (Italy), Etna (Italy), Yasur (Vanuatu), and Batu Tara (Indonesia), from puffing, through rapid explosions to normal explosions, with variable ejection parameters and relative abundance of gas, ash, and bombs. Using field observations and high-speed thermal infrared videos processed by a new algorithm, we identify the distinguishing characteristics of each type of activity and how they may relate and interact. In particular, we record that ash-poor normal explosions may be preceded and followed by the onset or the increase of the puffing activity, while ash-rich explosions are emergent, i.e., with inflation of the free surface followed directly by emission of increasingly large gas pockets. Overall, we see that all Strombolian activities form a continuum arising from a common mechanism and are modulated by the combination of two well-established controls: (1) the length of the bursting gas pocket with respect to the vent diameter and (2) the presence and thickness of a high-viscosity layer in the uppermost part of the volcanic conduit.

  11. The emission line spectrum of active galactic nuclei and the unifying scheme

    NASA Astrophysics Data System (ADS)

    Véron-Cetty, M. P.; Véron, P.

    Recent papers dealing with the most controversial aspects of AGNs are reviewed. They suggest interesting conclusions: all Seyferts can be described by a single parameter, the X-ray column density; radio loud AGNs may host a rapidly spinning black hole and radio quiet AGNs a slowly spinning black hole; high-ionization AGNs (Seyfert galaxies and QSOs) contain an optically thick, geometrically thin accretion disk, while low-ionization AGNs (Liners) contain an optically thin, geometrically thick accretion disk; a number of blazars have been classified as BLLs on the basis of insufficient data; most objects with weak broad emission lines are in fact HPQs; many objects have been called Liners although they are not AGNs but rather the result of stellar activity; type 2 QSOs exist, but are quite inconspicuous if radio quiet.

  12. Effect of exercise referral schemes in primary care on physical activity and improving health outcomes: systematic review and meta-analysis.

    PubMed

    Pavey, T G; Taylor, A H; Fox, K R; Hillsdon, M; Anokye, N; Campbell, J L; Foster, C; Green, C; Moxham, T; Mutrie, N; Searle, J; Trueman, P; Taylor, R S

    2011-11-04

    To assess the impact of exercise referral schemes on physical activity and health outcomes. Design Systematic review and meta-analysis. Medline, Embase, PsycINFO, Cochrane Library, ISI Web of Science, SPORTDiscus, and ongoing trial registries up to October 2009. We also checked study references. Study selection Design: randomised controlled trials or non-randomised controlled (cluster or individual) studies published in peer review journals. sedentary individuals with or without medical diagnosis. Exercise referral schemes defined as: clear referrals by primary care professionals to third party service providers to increase physical activity or exercise, physical activity or exercise programmes tailored to individuals, and initial assessment and monitoring throughout programmes. Comparators: usual care, no intervention, or alternative exercise referral schemes. Eight randomised controlled trials met the inclusion criteria, comparing exercise referral schemes with usual care (six trials), alternative physical activity intervention (two), and an exercise referral scheme plus a self determination theory intervention (one). Compared with usual care, follow-up data for exercise referral schemes showed an increased number of participants who achieved 90-150 minutes of physical activity of at least moderate intensity per week (pooled relative risk 1.16, 95% confidence intervals 1.03 to 1.30) and a reduced level of depression (pooled standardised mean difference -0.82, -1.28 to -0.35). Evidence of a between group difference in physical activity of moderate or vigorous intensity or in other health outcomes was inconsistent at follow-up. We did not find any difference in outcomes between exercise referral schemes and the other two comparator groups. None of the included trials separately reported outcomes in individuals with specific medical diagnoses. Substantial heterogeneity in the quality and nature of the exercise referral schemes across studies might have contributed

  13. Effect of exercise referral schemes in primary care on physical activity and improving health outcomes: systematic review and meta-analysis

    PubMed Central

    Taylor, A H; Fox, K R; Hillsdon, M; Anokye, N; Campbell, J L; Foster, C; Green, C; Moxham, T; Mutrie, N; Searle, J; Trueman, P; Taylor, R S

    2011-01-01

    Objective To assess the impact of exercise referral schemes on physical activity and health outcomes. Design Systematic review and meta-analysis. Data sources Medline, Embase, PsycINFO, Cochrane Library, ISI Web of Science, SPORTDiscus, and ongoing trial registries up to October 2009. We also checked study references. Study selection Design: randomised controlled trials or non-randomised controlled (cluster or individual) studies published in peer review journals. Population: sedentary individuals with or without medical diagnosis. Exercise referral schemes defined as: clear referrals by primary care professionals to third party service providers to increase physical activity or exercise, physical activity or exercise programmes tailored to individuals, and initial assessment and monitoring throughout programmes. Comparators: usual care, no intervention, or alternative exercise referral schemes. Results Eight randomised controlled trials met the inclusion criteria, comparing exercise referral schemes with usual care (six trials), alternative physical activity intervention (two), and an exercise referral scheme plus a self determination theory intervention (one). Compared with usual care, follow-up data for exercise referral schemes showed an increased number of participants who achieved 90-150 minutes of physical activity of at least moderate intensity per week (pooled relative risk 1.16, 95% confidence intervals 1.03 to 1.30) and a reduced level of depression (pooled standardised mean difference −0.82, −1.28 to −0.35). Evidence of a between group difference in physical activity of moderate or vigorous intensity or in other health outcomes was inconsistent at follow-up. We did not find any difference in outcomes between exercise referral schemes and the other two comparator groups. None of the included trials separately reported outcomes in individuals with specific medical diagnoses.Substantial heterogeneity in the quality and nature of the exercise referral

  14. GPU-BASED MONTE CARLO DUST RADIATIVE TRANSFER SCHEME APPLIED TO ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Heymann, Frank; Siebenmorgen, Ralf

    2012-05-20

    A three-dimensional parallel Monte Carlo (MC) dust radiative transfer code is presented. To overcome the huge computing-time requirements of MC treatments, the computational power of vectorized hardware is used, utilizing either multi-core computer power or graphics processing units. The approach is a self-consistent way to solve the radiative transfer equation in arbitrary dust configurations. The code calculates the equilibrium temperatures of two populations of large grains and stochastic heated polycyclic aromatic hydrocarbons. Anisotropic scattering is treated applying the Heney-Greenstein phase function. The spectral energy distribution (SED) of the object is derived at low spatial resolution by a photon counting procedure and at high spatial resolution by a vectorized ray tracer. The latter allows computation of high signal-to-noise images of the objects at any frequencies and arbitrary viewing angles. We test the robustness of our approach against other radiative transfer codes. The SED and dust temperatures of one- and two-dimensional benchmarks are reproduced at high precision. The parallelization capability of various MC algorithms is analyzed and included in our treatment. We utilize the Lucy algorithm for the optical thin case where the Poisson noise is high, the iteration-free Bjorkman and Wood method to reduce the calculation time, and the Fleck and Canfield diffusion approximation for extreme optical thick cells. The code is applied to model the appearance of active galactic nuclei (AGNs) at optical and infrared wavelengths. The AGN torus is clumpy and includes fluffy composite grains of various sizes made up of silicates and carbon. The dependence of the SED on the number of clumps in the torus and the viewing angle is studied. The appearance of the 10 {mu}m silicate features in absorption or emission is discussed. The SED of the radio-loud quasar 3C 249.1 is fit by the AGN model and a cirrus component to account for the far-infrared emission.

  15. Disk-driven hydromagnetic winds as a key ingredient of active galactic nuclei unification schemes

    NASA Technical Reports Server (NTRS)

    Konigl, Arieh; Kartje, John F.

    1994-01-01

    Centrifugally driven winds from the surfaces of magnetized accretion disks have been recognized as an attractive mechanism of removing the angular momentum of the accreted matter and of producing the bipolar outflows and jets that are often associated with compact astronomical objects. As previously suggested in the context of young stellar objects, such winds have unique observational manifestations stemming from their highly stratified density and velocity structure and from their exposure to the strong continuum radiation field of the compact object. We have applied this scenario to active galactic nuclei (AGNs) and investigated the properties of hydromagnetic outflows that originate within approximately 10(M(sub 8)) pc of the central 10(exp 8)(M(sub 8)) solar mass black hole. On the basis of our results, we propose that hydromagnetic disk-driven winds may underlie the classification of broad-line and narrow-line AGNs (e.g., the Seyfert 1/Seyfert 2 dichotomy) as well as the apparent dearth of luminous Seyfert 2 galaxies. More generally, we demonstrate that such winds could strongly influence the spectral characteristics of Seyfert galaxies, QSOs, and BL Lac objects (BLOs). In our picture, the torus is identified with the outer regions of the wind where dust uplifted from the disk surfaces by gas-grain collisions is embedded in the outflow. Using an efficient radiative transfer code, we show that the infrared emission of Seyfert galaxies and QSOs can be attributed to the reprocessing of the UV/soft X-ray AGN continuum by the dust in the wind and the disk. We demonstrate that the radiation pressure force flattens the dust distribution in objects with comparatively high (but possibly sub-Eddington) bolometric luminosities, and we propose this as one likely reason for the apparent paucity of narrow-line objects among certain high-luminosity AGNs. Using the XSTAR photoionization code, we show that the inner regions of the wind could naturally account for the warm

  16. Disk-driven hydromagnetic winds as a key ingredient of active galactic nuclei unification schemes

    NASA Technical Reports Server (NTRS)

    Konigl, Arieh; Kartje, John F.

    1994-01-01

    Centrifugally driven winds from the surfaces of magnetized accretion disks have been recognized as an attractive mechanism of removing the angular momentum of the accreted matter and of producing the bipolar outflows and jets that are often associated with compact astronomical objects. As previously suggested in the context of young stellar objects, such winds have unique observational manifestations stemming from their highly stratified density and velocity structure and from their exposure to the strong continuum radiation field of the compact object. We have applied this scenario to active galactic nuclei (AGNs) and investigated the properties of hydromagnetic outflows that originate within approximately 10(M(sub 8)) pc of the central 10(exp 8)(M(sub 8)) solar mass black hole. On the basis of our results, we propose that hydromagnetic disk-driven winds may underlie the classification of broad-line and narrow-line AGNs (e.g., the Seyfert 1/Seyfert 2 dichotomy) as well as the apparent dearth of luminous Seyfert 2 galaxies. More generally, we demonstrate that such winds could strongly influence the spectral characteristics of Seyfert galaxies, QSOs, and BL Lac objects (BLOs). In our picture, the torus is identified with the outer regions of the wind where dust uplifted from the disk surfaces by gas-grain collisions is embedded in the outflow. Using an efficient radiative transfer code, we show that the infrared emission of Seyfert galaxies and QSOs can be attributed to the reprocessing of the UV/soft X-ray AGN continuum by the dust in the wind and the disk. We demonstrate that the radiation pressure force flattens the dust distribution in objects with comparatively high (but possibly sub-Eddington) bolometric luminosities, and we propose this as one likely reason for the apparent paucity of narrow-line objects among certain high-luminosity AGNs. Using the XSTAR photoionization code, we show that the inner regions of the wind could naturally account for the warm

  17. Integrated separation scheme for measuring a suite of fission and activation products from a fresh mixed fission and activation product sample

    SciTech Connect

    Morley, Shannon M.; Seiner, Brienne N.; Finn, Erin C.; Greenwood, Lawrence R.; Smith, Steven C.; Gregory, Stephanie J.; Haney, Morgan M.; Lucas, Dawn D.; Arrigo, Leah M.; Beacham, Tere A.; Swearingen, Kevin J.; Friese, Judah I.; Douglas, Matthew; Metz, Lori A.

    2015-05-01

    Mixed fission and activation materials resulting from various nuclear processes and events contain a wide range of isotopes for analysis spanning almost the entire periodic table. In some applications such as environmental monitoring, nuclear waste management, and national security a very limited amount of material is available for analysis and characterization so an integrated analysis scheme is needed to measure multiple radionuclides from one sample. This work describes the production of a complex synthetic sample containing fission products, activation products, and irradiated soil and determines the percent recovery of select isotopes through the integrated chemical separation scheme. Results were determined using gamma energy analysis of separated fractions and demonstrate high yields of Ag (76 ± 6%), Au (94 ± 7%), Cd (59 ± 2%), Co (93 ± 5%), Cs (88 ± 3%), Fe (62 ± 1%), Mn (70 ± 7%), Np (65 ± 5%), Sr (73 ± 2%) and Zn (72 ± 3%). Lower yields (< 25%) were measured for Ga, Ir, Sc, and W. Based on the results of this experiment, a complex synthetic sample can be prepared with low atom/fission ratios and isotopes of interest accurately and precisely measured following an integrated chemical separation method.

  18. Immersion freezing of supermicron mineral dust particles: freezing results, testing different schemes for describing ice nucleation, and ice nucleation active site densities.

    PubMed

    Wheeler, M J; Mason, R H; Steunenberg, K; Wagstaff, M; Chou, C; Bertram, A K

    2015-05-14

    Ice nucleation on mineral dust particles is known to be an important process in the atmosphere. To accurately implement ice nucleation on mineral dust particles in atmospheric simulations, a suitable theory or scheme is desirable to describe laboratory freezing data in atmospheric models. In the following, we investigated ice nucleation by supermicron mineral dust particles [kaolinite and Arizona Test Dust (ATD)] in the immersion mode. The median freezing temperature for ATD was measured to be approximately -30 °C compared with approximately -36 °C for kaolinite. The freezing results were then used to test four different schemes previously used to describe ice nucleation in atmospheric models. In terms of ability to fit the data (quantified by calculating the reduced chi-squared values), the following order was found for ATD (from best to worst): active site, pdf-α, deterministic, single-α. For kaolinite, the following order was found (from best to worst): active site, deterministic, pdf-α, single-α. The variation in the predicted median freezing temperature per decade change in the cooling rate for each of the schemes was also compared with experimental results from other studies. The deterministic model predicts the median freezing temperature to be independent of cooling rate, while experimental results show a weak dependence on cooling rate. The single-α, pdf-α, and active site schemes all agree with the experimental results within roughly a factor of 2. On the basis of our results and previous results where different schemes were tested, the active site scheme is recommended for describing the freezing of ATD and kaolinite particles. We also used our ice nucleation results to determine the ice nucleation active site (INAS) density for the supermicron dust particles tested. Using the data, we show that the INAS densities of supermicron kaolinite and ATD particles studied here are smaller than the INAS densities of submicron kaolinite and ATD particles

  19. Impacts of human activities on nutrient transport in the Yellow River: The role of the Water-Sediment Regulation Scheme.

    PubMed

    Li, Xinyu; Chen, Hontao; Jiang, Xueyan; Yu, Zhigang; Yao, Qingzhen

    2017-08-15

    Anthropogenic activities alter the natural states of large rivers and their surrounding environment. The Yellow River is a well-studied case of a large river with heavy human control. An artificial managed water and sediment release system, known as the Water-Sediment Regulation Scheme (WSRS), has been carried out annually in the Yellow River since 2002. Nutrient concentrations and composition display significant time and space variations during the WSRS period. To figure out the anthropogenic impact of nutrient changes and transport in the Yellow River, biogeochemical observations were carried out in both middle reaches and lower reaches of the Yellow River during 2014 WSRS period. WSRS has a direct impact on water oxidation-reduction environment in the middle reaches; concentrations of nitrite (NO2(-)) and ammonium (NH4(+)) increased, while nitrate (NO3(-)) concentration decreased by enhanced denitrification. WSRS changed transport of water and sediment; dissolved silicate (DSi) in the middle reaches was directly controlled by sediments release during the WSRS while in the lower reaches, DSi changed with both sediments and water released from middle reaches. During the WSRS, the differences of nutrient fluxes and concentrations between lower reaches and middle reaches were significant; dissolved inorganic phosphorous (DIP) and dissolved inorganic nitrogen (DIN) were higher in low reaches because of anthropogenic inputs. Human intervention, especially WSRS, can apparently change the natural states of both the mainstream and estuarine environments of the Yellow River within a short time. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Degradation in urban air quality from construction activity and increased traffic arising from a road widening scheme.

    PubMed

    Font, Anna; Baker, Timothy; Mudway, Ian S; Purdie, Esme; Dunster, Christina; Fuller, Gary W

    2014-11-01

    Road widening schemes in urban areas are often proposed as a solution to traffic congestion and as a means of stimulating economic growth. There is however clear evidence that new or expanded roads rapidly fill with either displaced or induced traffic, offsetting any short-term gains in eased traffic flows. What has not been addressed in any great detail is the impact of such schemes on air quality, with modelled impact predictions seldom validated by measurements after the expansion of road capacity. In this study we made use of a road widening project in London to investigate the impact on ambient air quality (particulate matter, NOX, NO2) during and after the completion of the road works. PM10 increased during the construction period up to 15 μg m(-3) during working hours compared to concentrations before the road works. A box modelling approach was used to determine a median emission factor of 0.0022 kg PM10 m(-2) month(-1), three times larger than that used in the UK emission inventory (0.0007 kg PM10 m(-2) month(-1)). Peaks of activity released 0.0130 kg PM10 m(-2) month(-1), three and eight times smaller than the peak values used in the European and US inventories. After the completion of the widening there was an increase in all pollutants from the road during rush hour: 2-4 μg m(-3) for PM10; 1 μg m(-3) for PM2.5; 40 and 8 μg m(-3) for NOX and NO2, respectively. NO2 EU Limit Value was breached after the road development illustrating a notable deterioration in residential air quality. Additionally, PM10, but not PM2.5, glutathione dependent oxidative potential increased after the road was widened consistent with an increase in pro-oxidant components in the coarse particle mode, related to vehicle abrasion processes. These increased air pollution indices were associated with an increase in the number of cars, taxis and LGVs.

  1. Tabled Execution in Scheme

    SciTech Connect

    Willcock, J J; Lumsdaine, A; Quinlan, D J

    2008-08-19

    Tabled execution is a generalization of memorization developed by the logic programming community. It not only saves results from tabled predicates, but also stores the set of currently active calls to them; tabled execution can thus provide meaningful semantics for programs that seemingly contain infinite recursions with the same arguments. In logic programming, tabled execution is used for many purposes, both for improving the efficiency of programs, and making tasks simpler and more direct to express than with normal logic programs. However, tabled execution is only infrequently applied in mainstream functional languages such as Scheme. We demonstrate an elegant implementation of tabled execution in Scheme, using a mix of continuation-passing style and mutable data. We also show the use of tabled execution in Scheme for a problem in formal language and automata theory, demonstrating that tabled execution can be a valuable tool for Scheme users.

  2. Health Professionals' Perspectives on Exercise Referral and Physical Activity Promotion in Primary Care: Findings from a Process Evaluation of the National Exercise Referral Scheme in Wales

    ERIC Educational Resources Information Center

    Din, Nafees U.; Moore, Graham F.; Murphy, Simon; Wilkinson, Clare; Williams, Nefyn H.

    2015-01-01

    Background and objectives: Referring clinicians' experiences of exercise referral schemes (ERS) can provide valuable insights into their uptake. However, most qualitative studies focus on patient views only. This paper explores health professionals' perceptions of their role in promoting physical activity and experiences of a National Exercise…

  3. Health Professionals' Perspectives on Exercise Referral and Physical Activity Promotion in Primary Care: Findings from a Process Evaluation of the National Exercise Referral Scheme in Wales

    ERIC Educational Resources Information Center

    Din, Nafees U.; Moore, Graham F.; Murphy, Simon; Wilkinson, Clare; Williams, Nefyn H.

    2015-01-01

    Background and objectives: Referring clinicians' experiences of exercise referral schemes (ERS) can provide valuable insights into their uptake. However, most qualitative studies focus on patient views only. This paper explores health professionals' perceptions of their role in promoting physical activity and experiences of a National Exercise…

  4. Effectiveness and cost-effectiveness of a physical activity loyalty scheme for behaviour change maintenance: a cluster randomised controlled trial.

    PubMed

    Hunter, Ruth F; Brennan, Sarah F; Tang, Jianjun; Smith, Oliver J; Murray, Jennifer; Tully, Mark A; Patterson, Chris; Longo, Alberto; Hutchinson, George; Prior, Lindsay; French, David P; Adams, Jean; McIntosh, Emma; Kee, Frank

    2016-07-22

    Increasing physical activity in the workplace can provide employee physical and mental health benefits, and employer economic benefits through reduced absenteeism and increased productivity. The workplace is an opportune setting to encourage habitual activity. However, there is limited evidence on effective behaviour change interventions that lead to maintained physical activity. This study aims to address this gap and help build the necessary evidence base for effective, and cost-effective, workplace interventions. This cluster randomised control trial will recruit 776 office-based employees from public sector organisations in Belfast and Lisburn city centres, Northern Ireland. Participants will be randomly allocated by cluster to either the Intervention Group or Control Group (waiting list control). The 6-month intervention consists of rewards (retail vouchers, based on similar principles to high street loyalty cards), feedback and other evidence-based behaviour change techniques. Sensors situated in the vicinity of participating workplaces will promote and monitor minutes of physical activity undertaken by participants. Both groups will complete all outcome measures. The primary outcome is steps per day recorded using a pedometer (Yamax Digiwalker CW-701) for 7 consecutive days at baseline, 6, 12 and 18 months. Secondary outcomes include health, mental wellbeing, quality of life, work absenteeism and presenteeism, and use of healthcare resources. Process measures will assess intervention "dose", website usage, and intervention fidelity. An economic evaluation will be conducted from the National Health Service, employer and retailer perspective using both a cost-utility and cost-effectiveness framework. The inclusion of a discrete choice experiment will further generate values for a cost-benefit analysis. Participant focus groups will explore who the intervention worked for and why, and interviews with retailers will elucidate their views on the sustainability

  5. Indirect Z-Scheme BiOI/g-C3N4 Photocatalysts with Enhanced Photoreduction CO2 Activity under Visible Light Irradiation.

    PubMed

    Wang, Ji-Chao; Yao, Hong-Chang; Fan, Ze-Yu; Zhang, Lin; Wang, Jian-She; Zang, Shuang-Quan; Li, Zhong-Jun

    2016-02-17

    Rational design and construction of Z-scheme photocatalysts has received much attention in the field of CO2 reduction because of its great potential to solve the current energy and environmental crises. In this study, a series of Z-scheme BiOI/g-C3N4 photocatalysts are synthesized and their photocatalytic performance for CO2 reduction to produce CO, H2 and/or CH4 is evaluated under visible light irradiation (λ > 400 nm). The results show that the as-synthesized composites exhibit more highly efficient photocatalytic activity than pure g-C3N4 and BiOI and that the product yields change remarkably depending on the reaction conditions such as irradiation light wavelength. Emphasis is placed on identifying how the charge transfers across the heterojunctions and an indirect Z-scheme charge transfer mechanism is verified by detecting the intermediate I3(-) ions. The reaction mechanism is further proposed based on the detection of the intermediate (•)OH and H2O2. This work may be useful for rationally designing of new types of Z-scheme photocatalyst and provide some illuminating insights into the Z-scheme transfer mechanism.

  6. Accounting for Students' Schemes in the Development of a Graphical Process for Solving Polynomial Inequalities in Instrumented Activity

    ERIC Educational Resources Information Center

    Rivera, Ferdinand D.

    2007-01-01

    This paper provides an instrumental account of precalculus students' graphical process for solving polynomial inequalities. It is carried out in terms of the students' instrumental schemes as mediated by handheld graphing calculators and in cooperation with their classmates in a classroom setting. The ethnographic narrative relays an instrumental…

  7. Aligned Defrosting Dunes

    NASA Technical Reports Server (NTRS)

    2004-01-01

    17 August 2004 This July 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a group of aligned barchan sand dunes in the martian north polar region. At the time, the dunes were covered with seasonal frost, but the frost had begun to sublime away, leaving dark spots and dark outlines around the dunes. The surrounding plains exhibit small, diffuse spots that are also the result of subliming seasonal frost. This northern spring image, acquired on a descending ground track (as MGS was moving north to south on the 'night' side of Mars) is located near 78.8oN, 34.8oW. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the upper left.

  8. Exercise-referral scheme to promote physical activity among hypertensive patients: design of a cluster randomized trial in the Primary Health Care Units of Mexico's Social Security System.

    PubMed

    Gallegos-Carrillo, Katia; García-Peña, Carmen; Salmerón, Jorge; Salgado-de-Snyder, Velia Nelly; Vázquez-Cabrer, Gabriel; Lobelo, Felipe

    2014-07-09

    Although the benefits of physical activity (PA) on to prevent and manage non-communicable diseases are well known, strategies to help increase the levels of PA among different populations are limited. Exercise-referral schemes have emerged as one effective approach to promote PA; however, there is uncertainty about the feasibility and effectiveness of these schemes in settings outside high-income countries. This study will examine the effectiveness of a scheme to refer hypertensive patients identified in Primary Health Care facilities (PHCU) of the Mexican social security institution to a group PA program offered in the same institution. We will describe the methods of a cluster randomized trial study designed to evaluate the effectiveness of an exercise referral scheme to increasing physical activity in hypertensive patients compared to a non-referral scheme. Four PHCU were selected for the study; the PHCU will take part as the unit of randomization and sedentary hypertensive patients as the unit of assessment. 2 PHCU of control group (GC) will provide information to hypertensive patients about physical activity benefits and ways to increase it safely. 2 PHCU of intervention group (IG) will refer patients to sports facilities at the same institution, to follow a group-based PA program developed to increase the PA levels with a designed based on the Transtheoretical Model and Social Cognitive Theory. To evaluate the effects of the intervention as well as short-term maintenance of the intervention's effects, PA will be assessed at baseline, at 24 and 32 weeks of follow-up.The main outcome will be the difference before and after intervention in the percentage of participants meeting recommended levels of PA between and within intervention and control groups. PA will be measured through self-report and with objective measure by accelerometer. This study will allow us to evaluate a multidisciplinary effort to link the primary care and community-based areas of the same

  9. Enhancing visible light photocatalytic activity of direct Z-scheme SnS{sub 2}/Ag{sub 3}PO{sub 4} heterojunction photocatalysts

    SciTech Connect

    Luo, Jin Zhou, Xiaosong; Ma, Lin; Xu, Limei; Xu, Xuyao; Du, Zhihua; Zhang, Jinquan

    2016-09-15

    Highlights: • Novel direct Z-scheme SnS{sub 2}/Ag{sub 3}PO{sub 4} heterojunction photocatalysts are synthesized. • SnS{sub 2}/Ag{sub 3}PO{sub 4} exhibits much higher photocatalytic activity than pure SnS{sub 2} and Ag{sub 3}PO{sub 4}. • A possible photocatalytic mechanism was discussed in detail. - Abstract: Novel direct Z-scheme SnS{sub 2}/Ag{sub 3}PO{sub 4} heterojunction photocatalysts were successfully fabricated with SnS{sub 2} nanoplates hybridized by Ag{sub 3}PO{sub 4} nanoparticals via a facile hydrothermal and precipitation method and applied for the photocatalytic degradation of methyl orange in aqueous solution under visible light irradiation (λ > 420 nm). It was found that the photocatalytic performance of the SnS{sub 2} (2.0 wt%)/Ag{sub 3}PO{sub 4} heterojunction photocatalyst with 2.0 wt% SnS{sub 2} content was much higher than that of individual SnS{sub 2} and Ag{sub 3}PO{sub 4}. The enhanced photocatalytic activity could be ascribed to the efficient separation of photogenerated electrons and holes through the formation of direct Z-scheme system composed of SnS{sub 2} and Ag{sub 3}PO{sub 4}. Furthermore, the recycling experiments revealed that the photocorrosion behavior of Ag{sub 3}PO{sub 4} was strongly inhibited by SnS{sub 2}, it may be due to the photogenerated electrons of Ag{sub 3}PO{sub 4} would be quickly combined with the photogenerated holes of SnS{sub 2}. This work will be useful for the design of other direct Z-scheme visible-light-driven photocatalytic systems for application in energy conversion and environmental remediation.

  10. Pilot scheme for monitoring sickness absence in schools during the 2006/07 winter in England: can these data be used as a proxy for influenza activity?

    PubMed

    Mook, P; Joseph, C; Gates, P; Phin, N

    2007-12-01

    During influenza epidemics, school-aged children are amongst the first affected patients. They frequently then spread the virus within their families. Recognising influenza activity in schools may therefore be an important indicator of early activity in the wider community. During 2005/06, influenza B was associated with high levels of morbidity in school-children and over 600 schools outbreaks were reported to the Health Protection Agency by local Health Protection Units. While it is not possible to directly monitor influenza in schools, the feasibility and validity of using sentinel school absenteeism data, as a proxy for influenza in the community can be investigated. From week 02/07 to 20/07, eight primary and three secondary schools from five HPA regions were able, via the Department of Health-funded Health Protection Informatics website, to report daily electronic registration data, relating to absenteeism due to illness. Aggregated absenteeism data due to illness peaked the same week as indices for the age group comparable to that used by the Royal College for General Practitioners and NHS Direct schemes. When illness-defined absenteeism data was stratified into primary and secondary schools, absence in primary schools peaked one week before that in secondary schools and the established schemes for all ages. The start time of the study meant that initial increases in activity could not be measured. These encouraging results justify expanding this sentinel scheme to collect more rigorous evidence of the usefulness of absenteeism as a proxy for influenza activity and a tool to inform policy and trigger local responses.

  11. Fabrication and photocatalytic activity enhanced mechanism of direct Z-scheme g-C3N4/Ag2WO4 photocatalyst

    NASA Astrophysics Data System (ADS)

    Zhu, Bicheng; Xia, Pengfei; Li, Yao; Ho, Wingkei; Yu, Jiaguo

    2017-01-01

    Herein, a direct Z-scheme graphitic carbon nitride (g-C3N4)/silver tungstate (Ag2WO4) photocatalyst was prepared by a facile in situ precipitation method using g-C3N4 as a support and silver nitrate as a precursor. X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and elemental mapping demonstrated that β-Ag2WO4 nanoparticles were evenly distributed on the surface of g-C3N4 nanosheets, which acted as a support for the nucleation and growth of β-Ag2WO4 and inhibited the phase transformation of metastable β-Ag2WO4 to stable α-Ag2WO4. Photocatalytic experiments indicated that the g-C3N4/Ag2WO4 nanocomposite photocatalyst displayed a better photocatalytic activity than pure g-C3N4 and Ag2WO4 toward the degradation of methyl orange. The enhanced photocatalytic performance of g-C3N4/Ag2WO4 could be well explained by a direct Z-scheme photocatalytic mechanism. This mechanism was related to the efficient space separation of photogenerated electron-hole pairs and the great oxidation and reduction capabilities of the g-C3N4/Ag2WO4 system. This work provided new insights into the design and fabrication of g-C3N4-based direct Z-scheme photocatalysts.

  12. Fabrication of Z-scheme Ag3PO4/MoS2 composites with enhanced photocatalytic activity and stability for organic pollutant degradation

    NASA Astrophysics Data System (ADS)

    Zhu, Chaosheng; Zhang, Lu; Jiang, Bo; Zheng, Jingtang; Hu, Ping; Li, Sujuan; Wu, Mingbo; Wu, Wenting

    2016-07-01

    In this study, highly efficient visible-light-driven Ag3PO4/MoS2 composite photocatalysts with different weight ratios of MoS2 were prepared via the ethanol-water mixed solvents precipitation method and characterized by ICP, XRD, HRTEM, FE-SEM, BET, XPS, UV-vis DRS and PL analysis. Under visible-light irradiation, Ag3PO4/MoS2 composites exhibit excellent photocatalytic activity towards the degradation of organic pollutants in aqueous solution. The optimal composite with 0.648 wt% MoS2 content exhibits the highest photocatalytic activity, which can degrade almost all MB under visible-light irradiation within 60 min. Recycling experiments confirmed that the Ag3PO4/MoS2 catalysts had superior cycle performance and stability. The photocatalytic activity enhancement of Ag3PO4/MoS2 photocatalysts can be mainly ascribed to the efficient separation of photogenerated charge carriers and the stronger oxidation and reduction ability through a Z-scheme system composed of Ag3PO4, Ag and MoS2, in which Ag particles act as the charge separation center. The high photocatalytic stability is due to the successful inhibition of the photocorrosion of Ag3PO4 by transferring the photogenerated electrons of Ag3PO4 to MoS2. The evidence of the Z-scheme photocatalytic mechanism of the composite photocatalysts could be obtained from the active species trapping experiments and the photoluminescence technique.

  13. Psychosocial mediators of change in physical activity in the Welsh national exercise referral scheme: secondary analysis of a randomised controlled trial.

    PubMed

    Littlecott, Hannah J; Moore, Graham F; Moore, Laurence; Murphy, Simon

    2014-08-27

    While an increasing number of randomised controlled trials report impacts of exercise referral schemes (ERS) on physical activity, few have investigated the mechanisms through which increases in physical activity are produced. This study examines whether a National Exercise Referral Scheme (NERS) in Wales is associated with improvements in autonomous motivation, self-efficacy and social support, and whether change in physical activity is mediated by change in these psychosocial processes. A pragmatic randomised controlled trial of NERS across 12 LHBs in Wales. Questionnaires measured demographic data and physical activity at baseline. Participants (N = 2160) with depression, anxiety or CHD risk factors were referred by health professionals and randomly assigned to control or intervention. At six months psychological process measures were collected by questionnaire. At 12 months physical activity was assessed by 7 Day PAR telephone interview. Regressions tested intervention effects on psychosocial variables, physical activity before and after adjusting for mediators and socio demographic patterning. Significant intervention effects were found for autonomous motivation and social support for exercise at 6 months. No intervention effect was observed for self-efficacy. The data are consistent with a hypothesis of partial mediation of the intervention effect by autonomous motivation. Analysis of moderators showed significant improvements in relative autonomy in all subgroups. The greatest improvements in autonomous motivation were observed among patients who were least active at baseline. The present study offered key insights into psychosocial processes of change in an exercise referral scheme, with effects on physical activity mediated by autonomous motivation. Findings support the use of self-determination theory as a framework for ERS. Further research is required to explain socio-demographic patterning in responses to ERS, with changes in motivation occurring among

  14. Rational construction of Z-scheme Ag2CrO4/g-C3N4 composites with enhanced visible-light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Luo, Jin; Zhou, Xiaosong; Ma, Lin; Xu, Xuyao

    2016-12-01

    Novel visible-light driven Z-scheme Ag2CrO4/g-C3N4 composites with different contents of Ag2CrO4 were fabricated by a facile chemical precipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL) spectroscopy and photoelectrochemical measurements. Compared with individual g-C3N4 and Ag2CrO4, the Ag2CrO4/g-C3N4 composites displayed much larger photocatalytic activities for the photocatalytic degradation of methyl orange (MO) solution at room temperature under visible light irradiation (λ > 420 nm). Importantly, the optimum photodegradation rate constant of the Ag2CrO4/g-C3N4 composite at a theoretical weight content of 8.0% Ag2CrO4 for the photodegradation of MO was 0.0068 min-1, which was 5.7 and 4.3 times higher than that of pure g-C3N4 and Ag2CrO4, respectively. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electrons and holes at the Ag2CrO4/g-C3N4 interface imparted through the Z-scheme electron transfer. Furthermore, radical trap experiments depicted that both the holes and superoxide radical anions were thought to dominate oxidative species of the Ag2CrO4/g-C3N4 composite for MO degradation under visible light irradiation. Ultimately, a tentative Z-scheme photodegradation mechanism was proposed. This work may be useful for the rational design of new types of Z-scheme photocatalysts and provide some illuminate insights into the Z-scheme transfer mechanism for application in energy conversion and environmental remediation.

  15. Design of a direct Z-scheme photocatalyst: preparation and characterization of Bi₂O₃/g-C₃N₄ with high visible light activity.

    PubMed

    Zhang, Jinfeng; Hu, Yingfei; Jiang, Xiaoliang; Chen, Shifu; Meng, Sugang; Fu, Xianliang

    2014-09-15

    A direct Z-scheme photocatalyst Bi2O3/g-C3N4 was prepared by ball milling and heat treatment methods. The photocatalyst was characterized by X-ray powder diffraction (XRD), UV-vis diffuse reflection spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface areas, photoluminescence technique (PL), and electron spin resonance (ESR) technology. The photocatalytic activity was evaluated by degradation of methylene blue (MB) and rhodamine B (RhB). The results showed that Bi2O3/g-C3N4 exhibited a much higher photocatalytic activity than pure g-C3N4 under visible light illumination. The rate constants of MB and RhB degradation for Bi2O3(1.0wt.%)/g-C3N4 are about 3.4 and 5 times that of pure g-C3N4, respectively. The migration of photogenerated carriers adopts a Z-scheme mechanism. The photoexcited electrons in the CB of Bi2O3 and photogenerated holes in the VB of g-C3N4 are quickly combined, so the photoexcited electrons in the CB of g-C3N4 and holes in the VB of Bi2O3 participate in reduction and oxidation reactions, respectively. O2(-), OH and h(+) are the major reactive species for the Bi2O3/g-C3N4 photocatalytic system.

  16. In-situ preparation of Z-scheme AgI/Bi5O7I hybrid and its excellent photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Cui, Min; Yu, Jingxiong; Lin, Hongjun; Wu, Ying; Zhao, Leihong; He, Yiming

    2016-11-01

    The aim of this work was to synthesize, characterize and evaluate the photocatalytic activity of AgI/Bi5O7I composite photocatalyst under visible light irradiation. The photocatalyst was prepared by a simple one-step ionic reaction between Bi5O7I microrods and AgNO3 solutions, and was characterized by various techniques including X-ray diffraction (XRD), Raman spectroscopy (Raman), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The characterizations indicate that AgI particles were closely anchored on Bi5O7I micronods. During the photocataytic reaction, the composite was actually an Ag-AgI-Bi5O7I ternary system. The plasmonic effect of the formed Ag nanoparticles improved the visible light absorption performance, which benefits the photocatalytic reaction. However, more important was the formed heterojunction structure in the composite, which efficiently promoted the separation of electron-hole pairs by a plasmonic Z-scheme mechanism, and ultimately enhanced the photocatalytic activity. The optimal AgI/Bi5O7I composite showed a RhB degradation rate of 0.046 min-1, which was 3.83 and 6.57 times higher than those of Bi5O7I and AgI, respectively. This work may provide some insight into the design of novel and highly efficient Z-scheme visible-light photocatalysts.

  17. Integrated child development services scheme (ICDS) in India: its activities, present status and future strategy to reduce malnutrition.

    PubMed

    Kapil, U; Pradhan, R

    2000-09-01

    Integrated Child Development Services Scheme (ICDS) provides an integrated approach for converging all the basic services for improved child care, early stimulation and learning, health and nutrition, water and environmental sanitation aimed at the young children, expectant and lactating mothers, other women and adolescent girls in a community. Its objectives are: To improve nutritional and health status of children of 0-6 years; to reduce the incidence of mortality, morbidity, malnutrition and school dropout; to achieve effective co-ordination amongst various departments to promote child development; to lay foundation of proper psychological,physical and social development of the child; to enahance mother's capability to look after normal health and nutritional needs of the child. ICDS services are provided through a village based centre ie, the Anganwadicentre for the services of: Supplementary nutrition, immunisation, health check-up, referral services, treatment of minor illnesses, nutrition and health education to women, preschool education to children and supports for water supply, sanitation, etc. Several government departments and their services are co-ordinated at village, block, district, state and central levels. The Anganwadiworker is the most peripheral functionary which implements the programme services at the village/community level. In projects where able leadership has been provided, ICDS has been reported to be better. Though there are some shortcomings in ICDS, till future thrust of the programme is necessary for aiming of the upliftment of underprivileged section of the population. Operative research in various areas is suggested which can help in improving the efficiency of ICDS.

  18. Application of an active layer monitoring scheme based on the MODIS-LST product at a polygonal tundra site in Siberia

    NASA Astrophysics Data System (ADS)

    Langer, M.; Westermann, S.; Boike, J.

    2009-12-01

    A significant warming of the arctic has been reported, which is expected to continue within different scenarios of climate change. Permafrost is directly affected by this warming trend which emphasises the importance of a global permafrost monitoring scheme. Such monitoring projects can be realised by using remote sensing products, which provide continuous measurements on a global scale. Since permafrost is a ground temperature phenomenon, it is not directly accessible to remote sensing applications. Therefore, remote sensing products must be combined with models, facilitating access to the temperature dynamics of the deeper ground. A possible scheme makes use of land surface temperature (LST) products to drive permafrost models (e.g. Marchenko et al. 2009, Hachem et al. 2009). However, LST detection is problematic in heterogeneous landscapes, which can not be resolved by satellite sensors. This is especially true for permafrost areas, such as the polygonal tundra, which is a highly fractionated and characterized by wet and dry surface patches. In this study we analyze the potential effects of spatial differences in summer surface temperature at a polygonal tundra site at the Lena-River Delta. For this reason we apply a high-resolution thermal imaging system mounted on a 12 m tower. The obtained results clearly show that spatial temperature variations are significantly reduced by temporal averaging. Hence, the accuracy of satellite based permafrost monitoring is rather affected by the temporal than by the spatial resolution of the LST-products. We than investigate the performance of an active layer monitoring scheme based on a MODIS-LST product. For this purpose, surface temperatures obtained by MODIS and the thermal imaging system are projected into the ground, using a numerical solution of the heat transfer equation. The applied soil model feature a freeze thaw algorithm and a three phase heat conductivity / capacity model. The results are compared to

  19. Electromyographic Activity of Hand Muscles in a Motor Coordination Game: Effect of Incentive Scheme and Its Relation with Social Capital

    PubMed Central

    Censolo, Roberto; Craighero, Laila; Ponti, Giovanni; Rizzo, Leonzio; Canto, Rosario; Fadiga, Luciano

    2011-01-01

    Background A vast body of social and cognitive psychology studies in humans reports evidence that external rewards, typically monetary ones, undermine intrinsic motivation. These findings challenge the standard selfish-rationality assumption at the core of economic reasoning. In the present work we aimed at investigating whether the different modulation of a given monetary reward automatically and unconsciously affects effort and performance of participants involved in a game devoid of visual and verbal interaction and without any perspective-taking activity. Methodology/Principal Findings Twelve pairs of participants were submitted to a simple motor coordination game while recording the electromyographic activity of First Dorsal Interosseus (FDI), the muscle mainly involved in the task. EMG data show a clear effect of alternative rewards strategies on subjects' motor behavior. Moreover, participants' stock of relevant past social experiences, measured by a specifically designed questionnaire, was significantly correlated with EMG activity, showing that only low social capital subjects responded to monetary incentives consistently with a standard rationality prediction. Conclusions/Significance Our findings show that the effect of extrinsic motivations on performance may arise outside social contexts involving complex cognitive processes due to conscious perspective-taking activity. More importantly, the peculiar performance of low social capital individuals, in agreement with standard economic reasoning, adds to the knowledge of the circumstances that makes the crowding out/in of intrinsic motivation likely to occur. This may help in improving the prediction and accuracy of economic models and reconcile this puzzling effect of external incentives with economic theory. PMID:21464986

  20. Electromyographic activity of hand muscles in a motor coordination game: effect of incentive scheme and its relation with social capital.

    PubMed

    Censolo, Roberto; Craighero, Laila; Ponti, Giovanni; Rizzo, Leonzio; Canto, Rosario; Fadiga, Luciano

    2011-03-25

    A vast body of social and cognitive psychology studies in humans reports evidence that external rewards, typically monetary ones, undermine intrinsic motivation. These findings challenge the standard selfish-rationality assumption at the core of economic reasoning. In the present work we aimed at investigating whether the different modulation of a given monetary reward automatically and unconsciously affects effort and performance of participants involved in a game devoid of visual and verbal interaction and without any perspective-taking activity. Twelve pairs of participants were submitted to a simple motor coordination game while recording the electromyographic activity of First Dorsal Interosseus (FDI), the muscle mainly involved in the task. EMG data show a clear effect of alternative rewards strategies on subjects' motor behavior. Moreover, participants' stock of relevant past social experiences, measured by a specifically designed questionnaire, was significantly correlated with EMG activity, showing that only low social capital subjects responded to monetary incentives consistently with a standard rationality prediction. Our findings show that the effect of extrinsic motivations on performance may arise outside social contexts involving complex cognitive processes due to conscious perspective-taking activity. More importantly, the peculiar performance of low social capital individuals, in agreement with standard economic reasoning, adds to the knowledge of the circumstances that makes the crowding out/in of intrinsic motivation likely to occur. This may help in improving the prediction and accuracy of economic models and reconcile this puzzling effect of external incentives with economic theory.

  1. A photochemical activation scheme of inert dinitrogen by dinuclear Ru(II) and Fe(II) complexes.

    PubMed

    Reiher, Markus; Kirchner, Barbara; Hutter, Jürg; Sellmann, Dieter; Hess, Bernd Artur

    2004-09-20

    A general photochemical activation process of inert dinitrogen coordinated to two metal centers is presented on the basis of high-level DFT and ab initio calculations. The central feature of this activation process is the occupation of an antibonding pi* orbital upon electronic excitation from the singlet ground state S0 to the first excited singlet state S1. Populating the antibonding LUMO weakens the triple bond of dinitrogen. After a vertical excitation, the excited complex may structurally relax in the S1 state and approaches its minimum structure in the S1 state. This excited-state minimum structure features the dinitrogen bound in a diazenoid form, which exhibits a double bond and two lone pairs localized at the two nitrogen atoms, ready to be protonated. Reduction and de-excitation then yield the corresponding diazene complex; its generation represents the essential step in a nitrogen fixation and reduction protocol. The consecutive process of excitation, protonation, and reduction may be rearranged in any experimentally appropriate order. The protons needed for the reaction from dinitrogen to diazene can be provided by the ligand sphere of the complexes, which contains sulfur atoms acting as proton acceptors. These protonated thiolate functionalities bring protons close to the dinitrogen moiety. Because protonation does not change the pi*-antibonding character of the LUMO, the universal and well-directed character of the photochemical activation process makes it possible to protonate the dinitrogen complex before it is irradiated. The pi*-antibonding LUMO plays the central role in the activation process, since the diazenoid structure was obtained by excitation from various occupied orbitals as well as by a direct two-electron reduction (without photochemical activation) of the complex; that is, the important bending of N2 towards a diazenoid conformation can be achieved by populating the pi*-antibonding LUMO.

  2. Establishing a Proficiency Testing Scheme for Drinking Water Radiochemistry

    SciTech Connect

    Brookman, Brian

    2008-08-14

    As part of its international water proficiency testing (PT) scheme, 'Aquacheck', the LGC Proficiency Testing Group has established a new water radiochemistry PT scheme. The PT scheme is aimed at laboratories who undertake radiochemical analysis on drinking water samples as part of an environmental monitoring programme. Following a scheme design and feasibility study, the new scheme was established to monitor the laboratory performance of participants undertaking the determination of gross alpha, gross beta and tritium activity. Three rounds of the new water radiochemistry PT scheme are now complete. This paper explains the process of establishing such a scheme, reviews the results so far, and addresses future development of the scheme.

  3. In situ fabrication of novel Z-scheme Bi2WO6 quantum dots/g-C3N4 ultrathin nanosheets heterostructures with improved photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Liu, Tian-Yu; Huang, Ting; Liu, Xiao-Heng; Zhu, Jun-Wu; Duan, Guo-Rong; Yang, Xu-Jie

    2015-11-01

    The use of solar energy is a promising means for pollution abatement or environmental remediation. In the present work, we report the design and fabrication of Bi2WO6 QDs/g-C3N4 binary heterojunction photocatalysts with highly efficient solar light response, wherein the Bi2WO6 QDs were in situ uniformly immobilized on porous g-C3N4 ultrathin nanosheets (NSs) by one-pot hydrothermal strategy. The photocatalytic performance of the Bi2WO6 QDs/g-C3N4 NSs hybrid composites was evaluated for the photodegradation of Rhodamine B (RhB). It was found that the mass ratio of Bi2WO6 QDs to g-C3N4 nanosheets in the composites significantly affects the photocatalytic activity. Higher amounts of g-C3N4 nanosheets in Bi2WO6 QDs/g-C3N4 composites showed lower photocatalytic activity. The composite with 10 mg g-C3N4 nanosheets exhibited the highest photocatalytic activity, with nearly 11-fold enhancement in photocatalytic efficiency over pure Bi2WO6 QDs. Different from previous reports, a novel Z-scheme photocatalytic mechanism was proposed to explain the enhanced the photocatalytic efficiency.

  4. Membrane bioreactor (MBR) sludge inoculation in a hybrid process scheme concept to assist overloaded conventional activated sludge (CAS) process operations.

    PubMed

    Fenu, A; Roels, J; Van Damme, S; Wambecq, T; Weemaes, M; Thoeye, C; De Gueldre, G; Van De Steene, B

    2012-01-01

    This study analyzes the effect of inoculating membrane bioreactor (MBR) sludge in a parallel-operated overloaded conventional activated sludge (CAS) system. Modelling studies that showed the beneficial effect of this inoculation were confirmed though full scale tests. Total nitrogen (TN) removal in the CAS increased and higher nitrate formation rates were achieved. During MBR sludge inoculation, the TN removal in the CAS was proven to be dependent on MBR sludge loading. Special attention was given to the effect of inoculation on sludge quality. The MBR flocs, grown without selection pressure, were clearly distinct from the more compact flocs in the CAS system and also contained more filamentous bacteria. After inoculation the MBR flocs did not evolve into good-settling compact flocs, resulting in a decreasing sludge quality. During high flow conditions the effluent CAS contained more suspended solids. Sludge volume index, however, did not increase. Laboratory tests were held to determine the threshold volume of MBR sludge to be seeded into the CAS reactor. Above 16-30%, supernatant turbidity and scum formation increased markedly.

  5. Progress on the application of ELM control schemes to ITER scenarios from the non-active phase to DT operation

    NASA Astrophysics Data System (ADS)

    Loarte, A.; Huijsmans, G.; Futatani, S.; Baylor, L. R.; Evans, T. E.; Orlov, D. M.; Schmitz, O.; Becoulet, M.; Cahyna, P.; Gribov, Y.; Kavin, A.; Sashala Naik, A.; Campbell, D. J.; Casper, T.; Daly, E.; Frerichs, H.; Kischner, A.; Laengner, R.; Lisgo, S.; Pitts, R. A.; Saibene, G.; Wingen, A.

    2014-03-01

    Progress in the definition of the requirements for edge localized mode (ELM) control and the application of ELM control methods both for high fusion performance DT operation and non-active low-current operation in ITER is described. Evaluation of the power fluxes for low plasma current H-modes in ITER shows that uncontrolled ELMs will not lead to damage to the tungsten (W) divertor target, unlike for high-current H-modes in which divertor damage by uncontrolled ELMs is expected. Despite the lack of divertor damage at lower currents, ELM control is found to be required in ITER under these conditions to prevent an excessive contamination of the plasma by W, which could eventually lead to an increased disruptivity. Modelling with the non-linear MHD code JOREK of the physics processes determining the flow of energy from the confined plasma onto the plasma-facing components during ELMs at the ITER scale shows that the relative contribution of conductive and convective losses is intrinsically linked to the magnitude of the ELM energy loss. Modelling of the triggering of ELMs by pellet injection for DIII-D and ITER has identified the minimum pellet size required to trigger ELMs and, from this, the required fuel throughput for the application of this technique to ITER is evaluated and shown to be compatible with the installed fuelling and tritium re-processing capabilities in ITER. The evaluation of the capabilities of the ELM control coil system in ITER for ELM suppression is carried out (in the vacuum approximation) and found to have a factor of ˜2 margin in terms of coil current to achieve its design criterion, although such a margin could be substantially reduced when plasma shielding effects are taken into account. The consequences for the spatial distribution of the power fluxes at the divertor of ELM control by three-dimensional (3D) fields are evaluated and found to lead to substantial toroidal asymmetries in zones of the divertor target away from the separatrix

  6. Fabrication of Z-scheme plasmonic photocatalyst Ag@AgBr/g-C₃N₄ with enhanced visible-light photocatalytic activity.

    PubMed

    Yang, Yuxin; Guo, Wan; Guo, Yingna; Zhao, Yahui; Yuan, Xing; Guo, Yihang

    2014-04-30

    A series of Ag@AgBr grafted graphitic carbon nitride (Ag@AgBr/g-C3N4) plasmonic photocatalysts are fabricated through photoreducing AgBr/g-C3N4 hybrids prepared by deposition-precipitation method. The phase and chemical structures, electronic and optical properties as well as morphologies of Ag@AgBr/g-C3N4 heterostructures are well-characterized. Subsequently, the photocatalytic activity of Ag@AgBr/g-C3N4 is evaluated by the degradation of methyl orange (MO) and rhodamin B (RB) under visible-light irradiation. The enhanced photocatalytic activity of Ag@AgBr/g-C3N4 compared with g-C3N4 and Ag@AgBr is obtained and explained in terms of the efficient visible-light utilization efficiency as well as the construction of Z-scheme, which keeps photogenerated electrons and holes with high reduction and oxidation capability, evidenced by photoelectrochemical tests and free radical and hole scavenging experiments. Based on the intermediates identified in the reaction system, the photocatalytic degradation pathway of MO is put forward.

  7. Enhanced visible light activity on direct contact Z-scheme g-C3N4-TiO2 photocatalyst

    NASA Astrophysics Data System (ADS)

    Li, Juan; Zhang, Min; Li, Qiuye; Yang, Jianjun

    2017-01-01

    Direct contact Z-scheme g-C3N4-TiO2 nanocomposites without an electron mediator are prepared via simple annealing the mixture of bulk g-C3N4 and nanotube titanic acid (NTA) in air at 600 °C for 2 h. In the process of annealing, the bulk g-C3N4 transformed to ultra-thin g-C3N4 nanosheets, and NTA converted to a novel anatase TiO2, then the two components formed a close interaction. The XPS result reveals that some amount of nitrogen is doped into this novel-TiO2, and g-C3N4 nanosheets exist in the composites. The results of XRD, TEM and TG indicate that the thickness of g-C3N4 nanosheets is very thin. The ESR spectrum shows the existence of Ti3+ and single-electron-trapped oxygen vacancy in the 30%g-C3N4-TiO2 composites. In photocatalytic activity test, the 30%g-C3N4-TiO2 nanocomposites showed an excellent photo-oxidation activity of propylene under visible light irradiation (λ≥ 420 nm), and the removal efficiency of propylene reached as high as 56.6%, and the activity kept nearly 82% after four consecutive recycles. Photoluminescence (PL) result using terephthalic acid (TA) as a probe molecule indicated that the g-C3N4-TiO2 nanocomposites displayed a Z-sheme photocatalytic reaction system and this should be the main reason for the high photocatalytic activity. A possible photocatalytic mechanism was proposed on the basis of PL result and transient photocurrent-time curves.

  8. Microbial Performance of Food Safety Control and Assurance Activities in a Fresh Produce Processing Sector Measured Using a Microbial Assessment Scheme and Statistical Modeling.

    PubMed

    Njage, Patrick Murigu Kamau; Sawe, Chemutai Tonui; Onyango, Cecilia Moraa; Habib, I; Njagi, Edmund Njeru; Aerts, Marc; Molenberghs, Geert

    2017-01-01

    Current approaches such as inspections, audits, and end product testing cannot detect the distribution and dynamics of microbial contamination. Despite the implementation of current food safety management systems, foodborne outbreaks linked to fresh produce continue to be reported. A microbial assessment scheme and statistical modeling were used to systematically assess the microbial performance of core control and assurance activities in five Kenyan fresh produce processing and export companies. Generalized linear mixed models and correlated random-effects joint models for multivariate clustered data followed by empirical Bayes estimates enabled the analysis of the probability of contamination across critical sampling locations (CSLs) and factories as a random effect. Salmonella spp. and Listeria monocytogenes were not detected in the final products. However, none of the processors attained the maximum safety level for environmental samples. Escherichia coli was detected in five of the six CSLs, including the final product. Among the processing-environment samples, the hand or glove swabs of personnel revealed a higher level of predicted contamination with E. coli , and 80% of the factories were E. coli positive at this CSL. End products showed higher predicted probabilities of having the lowest level of food safety compared with raw materials. The final products were E. coli positive despite the raw materials being E. coli negative for 60% of the processors. There was a higher probability of contamination with coliforms in water at the inlet than in the final rinse water. Four (80%) of the five assessed processors had poor to unacceptable counts of Enterobacteriaceae on processing surfaces. Personnel-, equipment-, and product-related hygiene measures to improve the performance of preventive and intervention measures are recommended.

  9. Incorporating an advanced aerosol activation parameterization into WRF-CAM5: Model evaluation and parameterization intercomparison: An Advanced Aerosol Activation Scheme

    SciTech Connect

    Zhang, Yang; Zhang, Xin; Wang, Kai; He, Jian; Leung, L. Ruby; Fan, Jiwen; Nenes, Athanasios

    2015-07-22

    Aerosol activation into cloud droplets is an important process that governs aerosol indirect effects. The advanced treatment of aerosol activation by Fountoukis and Nenes (2005) and its recent updates, collectively called the FN series, have been incorporated into a newly developed regional coupled climate-air quality model based on the Weather Research and Forecasting model with the physics package of the Community Atmosphere Model version 5 (WRF-CAM5) to simulate aerosol-cloud interactions in both resolved and convective clouds. The model is applied to East Asia for two full years of 2005 and 2010. A comprehensive model evaluation is performed for model predictions of meteorological, radiative, and cloud variables, chemical concentrations, and column mass abundances against satellite data and surface observations from air quality monitoring sites across East Asia. The model performs overall well for major meteorological variables including near-surface temperature, specific humidity, wind speed, precipitation, cloud fraction, precipitable water, downward shortwave and longwave radiation, and column mass abundances of CO, SO2, NO2, HCHO, and O3 in terms of both magnitudes and spatial distributions. Larger biases exist in the predictions of surface concentrations of CO and NOx at all sites and SO2, O3, PM2.5, and PM10 concentrations at some sites, aerosol optical depth, cloud condensation nuclei over ocean, cloud droplet number concentration (CDNC), cloud liquid and ice water path, and cloud optical thickness. Compared with the default Abdul-Razzack Ghan (2000) parameterization, simulations with the FN series produce ~107–113% higher CDNC, with half of the difference attributable to the higher aerosol activation fraction by the FN series and the remaining half due to feedbacks in subsequent cloud microphysical processes. With the higher CDNC, the FN series are more skillful in simulating cloud water path, cloud optical thickness, downward shortwave radiation

  10. Monitoring of the ground surface temperature and the active layer in NorthEastern Canadian permafrost areas using remote sensing data assimilated in a climate land surface scheme.

    NASA Astrophysics Data System (ADS)

    Marchand, N.; Royer, A.; Krinner, G.; Roy, A.

    2014-12-01

    Projected future warming is particularly strong in the Northern high latitudes where increases of temperatures are up to 2 to 6 °C. Permafrost is present on 25 % of the northern hemisphere lands and contain high quantities of « frozen » carbon, estimated at 1400 Gt (40 % of the global terrestrial carbon). The aim of this study is to improve our understanding of the climate evolution in arctic areas, and more specifically of land areas covered by snow. The objective is to describe the ground temperature year round including under snow cover, and to analyse the active layer thickness evolution in relation to the climate variability. We use satellite data (fusion of MODIS land surface temperature « LST » and microwave AMSR-E brightness temperature « Tb ») assimilated in the Canadian Land Surface Scheme (CLASS) of the Canadian climate model coupled with a simple radiative transfer model (HUT). This approach benefits from the advantages of each of the data type in order to complete two objectives : 1- build a solid methodology for retrieving the ground temperature, with and without snow cover, in taïga and tundra areas ; 2 - from those retrieved ground temperatures, derive the summer melt duration and the active layer depth. We describe the coupling of the models and the methodology that adjusts the meteorological input parameters of the CLASS model (mainly air temperature and precipitations derived from the NARR database) in order to minimise the simulated LST and Tb ouputs in comparison with satellite measurements. Using ground-based meteorological data as validation references in NorthEastern Canadian tundra, the results show that the proposed approach improves the soil temperatures estimates when using the MODIS LST and Tb at 10 and 19 GHz to constrain the model in comparison with the model outputs without satellite data. Error analysis is discussed for the summer period (2.5 - 4 K) and for the snow covered winter period (2 - 3.5 K). Further steps are

  11. Twin Signature Schemes, Revisited

    NASA Astrophysics Data System (ADS)

    Schäge, Sven

    In this paper, we revisit the twin signature scheme by Naccache, Pointcheval and Stern from CCS 2001 that is secure under the Strong RSA (SRSA) assumption and improve its efficiency in several ways. First, we present a new twin signature scheme that is based on the Strong Diffie-Hellman (SDH) assumption in bilinear groups and allows for very short signatures and key material. A big advantage of this scheme is that, in contrast to the original scheme, it does not require a computationally expensive function for mapping messages to primes. We prove this new scheme secure under adaptive chosen message attacks. Second, we present a modification that allows to significantly increase efficiency when signing long messages. This construction uses collision-resistant hash functions as its basis. As a result, our improvements make the signature length independent of the message size. Our construction deviates from the standard hash-and-sign approach in which the hash value of the message is signed in place of the message itself. We show that in the case of twin signatures, one can exploit the properties of the hash function as an integral part of the signature scheme. This improvement can be applied to both the SRSA based and SDH based twin signature scheme.

  12. Identification of protein markers for the occurrence of defrosted material in milk through a MALDI-TOF-MS profiling approach.

    PubMed

    Arena, Simona; Salzano, Anna Maria; Scaloni, Andrea

    2016-09-16

    Mozzarella di Bufala Campana is a soft, stretched curd Italian cheese made from fresh buffalo milk that obtained the Protected Designation of Origin (PDO) registration in EU legislation. Seasonality of buffalo milk production, rapid cheese decay and transport of its preserving liquid have relevant practical/economic consequences for mozzarella production; consequently, a progressive diffusion of cheese products realized with frozen curd or frozen milk has recently been observed. In order to meet the demand of the dairy producers and consumers for a reduction of starting material adulterations and for the certification of the raw milk used for cheese manufacturing, we have developed a rapid/robust MALDI-TOF-MS polypeptide profiling procedure that assays material quality through the identification of specific markers of its freshness. Massive analysis of fresh and frozen buffalo milks (stored for different times) was realized to this purpose; a tough statistical evaluation of the resulting data ultimately permitted the typing of milk samples. We identified 28 polypeptide markers of the milk freezing storage, among which 13 and 15 showed down- and over-representation, respectively. Quantitative data were confirmed by an independent analytical approach on selected markers. GLYCAM1-derived phosphopeptides (1-53), β-casein-derived phosphopeptides (1-68), β-casein-derived γ2-, γ3- and γ4-fragments, α-lactalbumin and β-lactoglobulin were components showing the highest significance. The occurrence of the first compounds in buffalo milk is here described for the first time; their formation in the frozen material was ascribed to the activity of plasmin or of unknown bacterial proteases/peptidases stable at low temperatures. In conclusion, data reported here suggest the application of this MALDI-TOF-MS polypeptide profiling platform to other high-quality dairy productions, in which milk freshness has important consequences on final product organoleptic properties. In

  13. Defrosting of Russell Crater Dunes

    NASA Technical Reports Server (NTRS)

    2007-01-01

    These two images (at right) were acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) 39 days apart at 19:10 UTC (2:10 PM EST) on December 28, 2006 (upper right) and at 20:06 UTC (3:06 PM EST) on February 5, 2007 (lower right). These CRISM data were acquired in 544 colors covering the wavelength range from 0.36-3.92 micrometers, and show features as small as 20 meters (about 65 feet) across. Both images are false color composites of bands at 2.5, 1.5, and 1.25 micrometers, and are nearly centered at the same location, 54.875oS, 12.919oE (upper right) and 54.895oS, 12.943oE (lower right). Each image is approximately 11 kilometers (7 miles) across at its narrowest. These are part of a series of images capturing the evolution of carbon dioxide frost on the surface of the dunes in Russell Crater.

    Russell Crater is one of many craters in the southern highland region of Mars that contain large areas of sand dunes. The sand in these dunes has accumulated over a very long time period -- perhaps millions of years -- as wind blows over the highland terrain, picking up sand in some places and depositing in others. The topography of the craters forces the wind to blow up and over the crater rims, and the wind often isn't strong enough to keep the tiny grains suspended. This makes the sand fall to the ground and gradually pile up, and over time the surface breezes shape the sand into ripples and dunes. A similar process is at work at the Great Sand Dunes National Park and Preserve in Colorado, USA.

    The above left image shows a THEMIS daytime infrared mosaic of Russell Crater and the location of its (approximately) 30-kilometer wide dune field in the northeastern quadrant of the crater floor. Superposed on this view and shown enlarged at the upper right is CRISM image FRT000039DF. This CRISM image was acquired during the late Martian southern winter (solar longitude = 157.7o), and the bright blue in this false color composite indicates the presence of carbon dioxide frost (dry ice) on the dunes. Sunlight is coming from the northeast, and the sunlit faces of the dunes appear red because they show very little frost compared to the colder, more shadowed areas. Thirty-nine days later at the beginning of southern spring (solar longitude = 178.9o), CRISM image FRT000042AA (lower right) was acquired almost at the same location. Notably, the bright blue frost-rich areas are considerably smaller and subdued, with slim patches only observed on the shadowed sides of the dunes that are most protected from the warmth of the rising sun. As the southern season continues to march toward summer, all of the frost will soon be gone and won't return until the next Martian winter.

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.

  14. Defrosting of Russell Crater Dunes

    NASA Technical Reports Server (NTRS)

    2007-01-01

    These two images (at right) were acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) 39 days apart at 19:10 UTC (2:10 PM EST) on December 28, 2006 (upper right) and at 20:06 UTC (3:06 PM EST) on February 5, 2007 (lower right). These CRISM data were acquired in 544 colors covering the wavelength range from 0.36-3.92 micrometers, and show features as small as 20 meters (about 65 feet) across. Both images are false color composites of bands at 2.5, 1.5, and 1.25 micrometers, and are nearly centered at the same location, 54.875oS, 12.919oE (upper right) and 54.895oS, 12.943oE (lower right). Each image is approximately 11 kilometers (7 miles) across at its narrowest. These are part of a series of images capturing the evolution of carbon dioxide frost on the surface of the dunes in Russell Crater.

    Russell Crater is one of many craters in the southern highland region of Mars that contain large areas of sand dunes. The sand in these dunes has accumulated over a very long time period -- perhaps millions of years -- as wind blows over the highland terrain, picking up sand in some places and depositing in others. The topography of the craters forces the wind to blow up and over the crater rims, and the wind often isn't strong enough to keep the tiny grains suspended. This makes the sand fall to the ground and gradually pile up, and over time the surface breezes shape the sand into ripples and dunes. A similar process is at work at the Great Sand Dunes National Park and Preserve in Colorado, USA.

    The above left image shows a THEMIS daytime infrared mosaic of Russell Crater and the location of its (approximately) 30-kilometer wide dune field in the northeastern quadrant of the crater floor. Superposed on this view and shown enlarged at the upper right is CRISM image FRT000039DF. This CRISM image was acquired during the late Martian southern winter (solar longitude = 157.7o), and the bright blue in this false color composite indicates the presence of carbon dioxide frost (dry ice) on the dunes. Sunlight is coming from the northeast, and the sunlit faces of the dunes appear red because they show very little frost compared to the colder, more shadowed areas. Thirty-nine days later at the beginning of southern spring (solar longitude = 178.9o), CRISM image FRT000042AA (lower right) was acquired almost at the same location. Notably, the bright blue frost-rich areas are considerably smaller and subdued, with slim patches only observed on the shadowed sides of the dunes that are most protected from the warmth of the rising sun. As the southern season continues to march toward summer, all of the frost will soon be gone and won't return until the next Martian winter.

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.

  15. [PICS: pharmaceutical inspection cooperation scheme].

    PubMed

    Morénas, J

    2009-01-01

    The pharmaceutical inspection cooperation scheme (PICS) is a structure containing 34 participating authorities located worldwide (October 2008). It has been created in 1995 on the basis of the pharmaceutical inspection convention (PIC) settled by the European free trade association (EFTA) in1970. This scheme has different goals as to be an international recognised body in the field of good manufacturing practices (GMP), for training inspectors (by the way of an annual seminar and experts circles related notably to active pharmaceutical ingredients [API], quality risk management, computerized systems, useful for the writing of inspection's aide-memoires). PICS is also leading to high standards for GMP inspectorates (through regular crossed audits) and being a room for exchanges on technical matters between inspectors but also between inspectors and pharmaceutical industry.

  16. Exercise-referral scheme to promote physical activity among hypertensive patients: design of a cluster randomized trial in the Primary Health Care Units of Mexico’s Social Security System

    PubMed Central

    2014-01-01

    Background Although the benefits of physical activity (PA) on to prevent and manage non-communicable diseases are well known, strategies to help increase the levels of PA among different populations are limited. Exercise-referral schemes have emerged as one effective approach to promote PA; however, there is uncertainty about the feasibility and effectiveness of these schemes in settings outside high-income countries. This study will examine the effectiveness of a scheme to refer hypertensive patients identified in Primary Health Care facilities (PHCU) of the Mexican social security institution to a group PA program offered in the same institution. Methods and design We will describe the methods of a cluster randomized trial study designed to evaluate the effectiveness of an exercise referral scheme to increasing physical activity in hypertensive patients compared to a non-referral scheme. Four PHCU were selected for the study; the PHCU will take part as the unit of randomization and sedentary hypertensive patients as the unit of assessment. 2 PHCU of control group (GC) will provide information to hypertensive patients about physical activity benefits and ways to increase it safely. 2 PHCU of intervention group (IG) will refer patients to sports facilities at the same institution, to follow a group-based PA program developed to increase the PA levels with a designed based on the Transtheoretical Model and Social Cognitive Theory. To evaluate the effects of the intervention as well as short-term maintenance of the intervention’s effects, PA will be assessed at baseline, at 24 and 32 weeks of follow-up. The main outcome will be the difference before and after intervention in the percentage of participants meeting recommended levels of PA between and within intervention and control groups. PA will be measured through self-report and with objective measure by accelerometer. Discussion This study will allow us to evaluate a multidisciplinary effort to link the primary

  17. Compact Spreader Schemes

    SciTech Connect

    Placidi, M.; Jung, J. -Y.; Ratti, A.; Sun, C.

    2014-07-25

    This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.

  18. Compact spreader schemes

    NASA Astrophysics Data System (ADS)

    Placidi, M.; Jung, J.-Y.; Ratti, A.; Sun, C.

    2014-12-01

    This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.

  19. Mediator-free direct Z-scheme photocatalytic system: BiVO4/g-C3N4 organic-inorganic hybrid photocatalyst with highly efficient visible-light-induced photocatalytic activity.

    PubMed

    Tian, Na; Huang, Hongwei; He, Ying; Guo, Yuxi; Zhang, Tierui; Zhang, Yihe

    2015-03-07

    We disclose the fabrication of a mediator-free direct Z-scheme photocatalyst system BiVO4/g-C3N4 using a mixed-calcination method based on the more reliable interfacial interaction. The facet coupling occurred between the g-C3N4 (002) and BiVO4 (121), and it was revealed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). The crystal structure and optical properties of the as-prepared samples have also been characterized by Fourier-transform infrared (FTIR), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra (DRS) in details. The photocatalytic experiments indicated that the BiVO4/g-C3N4 composite photocatalysts display a significantly enhanced photocatalytic activity pertaining to RhB degradation and photocurrent generation (PC) compared to the pristine BiVO4 and g-C3N4. This remarkably improved photocatalytic performance should be attributed to the fabrication of a direct Z-scheme system of BiVO4/g-C3N4, which can result in a more efficient separation of photoinduced charge carriers than band-band transfer, thus endowing it with the much more powerful oxidation and reduction capability, as confirmed by the photoluminescence (PL) spectra and electrochemical impedance spectra (EIS). The Z-scheme mechanism of BiVO4/g-C3N4 heterostructure was verified by a series of combined techniques, including the active species trapping experiments, NBT transformation and terephthalic acid photoluminescence probing technique (TA-PL) over BiVO4/g-C3N4 composites and the pristine samples. The present work not only furthered the understanding of mediator-free Z-scheme photocatalysis, but also shed new light on the design of heterostructural photocatalysts with high-performance.

  20. Check-Digit Schemes.

    ERIC Educational Resources Information Center

    Wheeler, Mary L.

    1994-01-01

    Discusses the study of identification codes and check-digit schemes as a way to show students a practical application of mathematics and introduce them to coding theory. Examples include postal service money orders, parcel tracking numbers, ISBN codes, bank identification numbers, and UPC codes. (MKR)

  1. Fabrication of a novel Z-scheme g-C3N4/Bi4O7 heterojunction photocatalyst with enhanced visible light-driven activity toward organic pollutants.

    PubMed

    Sun, Meng; Wang, Yu; Shao, Yu; He, Yunhui; Zeng, Qi; Liang, Huikai; Yan, Tao; Du, Bin

    2017-09-01

    In this work, highly efficient g-C3N4/Bi4O7 heterojunction photocatalysts have been successfully fabricated by a facile method. Compared with the bare photocatalysts, the obtained g-C3N4/Bi4O7 hybrid photocatalysts exhibited efficient degradation activity toward methylene blue (MB), phenol, rhodamine B (RhB), and bisphenol A (BPA) under visible light irradiation. The influences of different g-C3N4 contents on the photocatalytic efficiency of the hybrid photocatalysts have been investigated. The results revealed that the g-C3N4/Bi4O7 with g-C3N4 mass ratio of 30% exhibited the best photocatalytic activity. The activity enhancement should be ascribed to the improved visible light adsorption as well as the effective Z-scheme charge transfer according to the energy band theory. The UV-vis diffuse reflectance spectra (DRS) shows that the absorption edge of g-C3N4 move towards longer wavelength with the increment of Bi4O7 component. The strong connection between g-C3N4 and Bi4O7 was investigated using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Subsequently, the effective Z-scheme charge transfer has also been verified by using transient photocurrent measurements and electrochemical impedance spectroscopy. Controlled experiments proved that active species of O2(-) and h(+) were produced in the degradation system, which played the major role in the degradation of MB. A possible Z-scheme degradation mechanism over g-C3N4/Bi4O7 hybrid photocatalysts was proposed. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Precise control of a four degree-of-freedom permanent magnet biased active magnetic bearing system in a magnetically suspended direct-driven spindle using neural network inverse scheme

    NASA Astrophysics Data System (ADS)

    Sun, Xiaodong; Su, Bokai; Chen, Long; Yang, Zebin; Xu, Xing; Shi, Zhou

    2017-05-01

    The capacity of improving the control accuracy and dynamic performance of a four degree-of-freedom (DOF) permanent magnet biased active magnetic bearing (PMBAMB) system is critical to developing and maintaining a high precision application in a magnetically suspended direct-driven spindle system. The 4-DOF PMBAMB system, however, is a multivariable, strong coupled and nonlinear system with unavoidable and unmeasured external disturbances, in addition to having parameter variations. The satisfactory control performance cannot be obtained by using traditional strategies. Therefore, it is important to present a novel control scheme to construct a robust controller with good closed-loop capability. This paper proposes a new decoupling control scheme for a 4-DOF PMBAMB in a direct-driven spindle system based on the neural network inverse (NNI) and 2- degree-of-freedom (DOF) internal model control method. By combining the inversion of the 4-DOF PMBAMB system with its original system, a new pseudolinear system can be developed. In addition, by introducing the 2-DOF internal model controller into the pseudolinear system to design extra closed-loop controllers, we can effectively eliminate the influence of the unmodeled dynamics to the decoupling control accuracy, as well as adjust the properties of tracking and disturbance rejection independently. The experimental results demonstrate the effectiveness of the proposed control scheme.

  3. Hybridization schemes for clusters

    NASA Astrophysics Data System (ADS)

    Wales, David J.

    The concept of an optimum hybridization scheme for cluster compounds is developed with particular reference to electron counting. The prediction of electron counts for clusters and the interpretation of the bonding is shown to depend critically upon the presumed hybridization pattern of the cluster vertex atoms. This fact has not been properly appreciated in previous work, particularly in applications of Stone's tensor surface harmonic (TSH) theory, but is found to be a useful tool when dealt with directly. A quantitative definition is suggested for the optimum cluster hybridization pattern based directly upon the ease of interpretation of the molecular orbitals, and results are given for a range of species. The relationship of this scheme to the detailed cluster geometry is described using Löwdin's partitioned perturbation theory, and the success and range of application of TSH theory are discussed.

  4. Scalable Nonlinear Compact Schemes

    SciTech Connect

    Ghosh, Debojyoti; Constantinescu, Emil M.; Brown, Jed

    2014-04-01

    In this work, we focus on compact schemes resulting in tridiagonal systems of equations, specifically the fifth-order CRWENO scheme. We propose a scalable implementation of the nonlinear compact schemes by implementing a parallel tridiagonal solver based on the partitioning/substructuring approach. We use an iterative solver for the reduced system of equations; however, we solve this system to machine zero accuracy to ensure that no parallelization errors are introduced. It is possible to achieve machine-zero convergence with few iterations because of the diagonal dominance of the system. The number of iterations is specified a priori instead of a norm-based exit criterion, and collective communications are avoided. The overall algorithm thus involves only point-to-point communication between neighboring processors. Our implementation of the tridiagonal solver differs from and avoids the drawbacks of past efforts in the following ways: it introduces no parallelization-related approximations (multiprocessor solutions are exactly identical to uniprocessor ones), it involves minimal communication, the mathematical complexity is similar to that of the Thomas algorithm on a single processor, and it does not require any communication and computation scheduling.

  5. Massive momentum-subtraction scheme

    NASA Astrophysics Data System (ADS)

    Boyle, Peter; Del Debbio, Luigi; Khamseh, Ava

    2017-03-01

    A new renormalization scheme is defined for fermion bilinears in QCD at nonvanishing quark masses. This new scheme, denoted RI/mSMOM, preserves the benefits of the nonexceptional momenta introduced in the RI/SMOM scheme and allows a definition of renormalized composite fields away from the chiral limit. Some properties of the scheme are investigated by performing explicit one-loop computation in dimensional regularization.

  6. ESCAP mobile training scheme.

    PubMed

    Yasas, F M

    1977-01-01

    In response to a United Nations resolution, the Mobile Training Scheme (MTS) was set up to provide training to the trainers of national cadres engaged in frontline and supervisory tasks in social welfare and rural development. The training is innovative in its being based on an analysis of field realities. The MTS team consisted of a leader, an expert on teaching methods and materials, and an expert on action research and evaluation. The country's trainers from different departments were sent to villages to work for a short period and to report their problems in fulfilling their roles. From these grass roots experiences, they made an analysis of the job, determining what knowledge, attitude and skills it required. Analysis of daily incidents and problems were used to produce indigenous teaching materials drawn from actual field practice. How to consider the problems encountered through government structures for policy making and decisions was also learned. Tasks of the students were to identify the skills needed for role performance by job analysis, daily diaries and project histories; to analyze the particular community by village profiles; to produce indigenous teaching materials; and to practice the role skills by actual role performance. The MTS scheme was tried in Nepal in 1974-75; 3 training programs trained 25 trainers and 51 frontline workers; indigenous teaching materials were created; technical papers written; and consultations were provided. In Afghanistan the scheme was used in 1975-76; 45 participants completed the training; seminars were held; and an ongoing Council was created. It is hoped that the training program will be expanded to other countries.

  7. Convering ARQ schemes

    NASA Astrophysics Data System (ADS)

    Arazi, B.; Hsieh, J.

    1985-04-01

    The parity check matrix of an (n, k, t) linear error-correcting code provides a unique mapping between binary vectors of length n, whose Hamming weight does not exceed t, and binary vectors of length (n-k) which are the syndrome obtained by multiplying the vector of length n by the parity check matrix. This enables the 'compression' of binary vectors having a limited Hamming weight. It is shown in the paper how this principle can be applied in ARQ schemes, where, upon detection of an error in a received message, further retransmitted messages can be made shorter from one retransmission to the next.

  8. New LNG process scheme

    SciTech Connect

    Foglietta, J.H.

    1999-07-01

    A new LNG cycle has been developed for base load liquefaction facilities. This new design offers a different technical and economical solution comparing in efficiency with the classical technologies. The new LNG scheme could offer attractive business opportunities to oil and gas companies that are trying to find paths to monetize gas sources more effectively; particularly for remote or offshore locations where smaller scale LNG facilities might be applicable. This design offers also an alternative route to classic LNG projects, as well as alternative fuel sources. Conceived to offer simplicity and access to industry standard equipment, This design is a hybrid result of combining a standard refrigeration system and turboexpander technology.

  9. Verification and accreditation schemes for climate change activities: A review of requirements for verification of greenhouse gas reductions and accreditation of verifiers—Implications for long-term carbon sequestration

    NASA Astrophysics Data System (ADS)

    Roed-Larsen, Trygve; Flach, Todd

    The purpose of this chapter is to provide a review of existing national and international requirements for verification of greenhouse gas reductions and associated accreditation of independent verifiers. The credibility of results claimed to reduce or remove anthropogenic emissions of greenhouse gases (GHG) is of utmost importance for the success of emerging schemes to reduce such emissions. Requirements include transparency, accuracy, consistency, and completeness of the GHG data. The many independent verification processes that have developed recently now make up a quite elaborate tool kit for best practices. The UN Framework Convention for Climate Change and the Kyoto Protocol specifications for project mechanisms initiated this work, but other national and international actors also work intensely with these issues. One initiative gaining wide application is that taken by the World Business Council for Sustainable Development with the World Resources Institute to develop a "GHG Protocol" to assist companies in arranging for auditable monitoring and reporting processes of their GHG activities. A set of new international standards developed by the International Organization for Standardization (ISO) provides specifications for the quantification, monitoring, and reporting of company entity and project-based activities. The ISO is also developing specifications for recognizing independent GHG verifiers. This chapter covers this background with intent of providing a common understanding of all efforts undertaken in different parts of the world to secure the reliability of GHG emission reduction and removal activities. These verification schemes may provide valuable input to current efforts of securing a comprehensive, trustworthy, and robust framework for verification activities of CO2 capture, transport, and storage.

  10. Scheme of thinking quantum systems

    NASA Astrophysics Data System (ADS)

    Yukalov, V. I.; Sornette, D.

    2009-11-01

    A general approach describing quantum decision procedures is developed. The approach can be applied to quantum information processing, quantum computing, creation of artificial quantum intelligence, as well as to analyzing decision processes of human decision makers. Our basic point is to consider an active quantum system possessing its own strategic state. Processing information by such a system is analogous to the cognitive processes associated to decision making by humans. The algebra of probability operators, associated with the possible options available to the decision maker, plays the role of the algebra of observables in quantum theory of measurements. A scheme is advanced for a practical realization of decision procedures by thinking quantum systems. Such thinking quantum systems can be realized by using spin lattices, systems of magnetic molecules, cold atoms trapped in optical lattices, ensembles of quantum dots, or multilevel atomic systems interacting with electromagnetic field.

  11. On the role of SMA modeling in simulating NiTinol self-expanding stenting surgeries to assess the performance characteristics of mechanical and thermal activation schemes.

    PubMed

    Saleeb, A F; Dhakal, B; Owusu-Danquah, J S

    2015-09-01

    The work is focused on a detailed simulation of the key stages involved in the NiTinol self-expanding stenting surgical procedure; i.e., crimping, deployment, SMA activation, as well as post-surgery steady-state cyclic behavior mimicking the systolic-to-diastolic pressure oscillations. To this end, a general multi-mechanism SMA model was utilized, whose calibration was completed using the test data from simple isothermal uniaxial tension experiments. The emphasis in the study was placed on the comparison of two alternative SMA activation protocols, in terms of both the immediate and long-term (post-surgery) performance characteristics. The first is 'hard' mechanical activation utilizing superelasticity, and the second is 'soft' thermal activation relying upon the combined one-way shape memory effect and constrained-recovery characteristics of the NiTinol material. The important findings are (1) the thermal activation protocol is far superior compared to the mechanical counterpart, from the point of view of lower magnitudes of the induced outward chronic forces, lesser developed stresses in the host tissue, as well as higher compression ratio with lesser crimping force for the same geometry of initial stent memory configuration, (2) the thermal activation protocol completely bypassed the complications of maintaining the high restraining force during deployment of the stent, and (3) there is no indication of any detrimental functional fatigue/degradation in the cured stenotic artery during cyclic pressure oscillations.

  12. Fault Tolerant Cache Schemes

    NASA Astrophysics Data System (ADS)

    Tu, H.-Yu.; Tasneem, Sarah

    Most of modern microprocessors employ on—chip cache memories to meet the memory bandwidth demand. These caches are now occupying a greater real es tate of chip area. Also, continuous down scaling of transistors increases the possi bility of defects in the cache area which already starts to occupies more than 50% of chip area. For this reason, various techniques have been proposed to tolerate defects in cache blocks. These techniques can be classified into three different cat egories, namely, cache line disabling, replacement with spare block, and decoder reconfiguration without spare blocks. This chapter examines each of those fault tol erant techniques with a fixed typical size and organization of L1 cache, through extended simulation using SPEC2000 benchmark on individual techniques. The de sign and characteristics of each technique are summarized with a view to evaluate the scheme. We then present our simulation results and comparative study of the three different methods.

  13. On Some Numerical Dissipation Schemes

    NASA Technical Reports Server (NTRS)

    Swanson, R. C.; Radespiel, R.; Turkel, E.

    1998-01-01

    Several schemes for introducing an artificial dissipation into a central difference approximation to the Euler and Navier Stokes equations are considered. The focus of the paper is on the convective upwind and split pressure (CUSP) scheme, which is designed to support single interior point discrete shock waves. This scheme is analyzed and compared in detail with scalar dissipation and matrix dissipation (MATD) schemes. Resolution capability is determined by solving subsonic, transonic, and hypersonic flow problems. A finite-volume discretization and a multistage time-stepping scheme with multigrid are used to compute solutions to the flow equations. Numerical solutions are also compared with either theoretical solutions or experimental data. For transonic airfoil flows the best accuracy on coarse meshes for aerodynamic coefficients is obtained with a simple MATD scheme. The coarse-grid accuracy for the original CUSP scheme is improved by modifying the limiter function used with the scheme, giving comparable accuracy to that obtained with the MATD scheme. The modifications reduce the background dissipation and provide control over the regions where the scheme can become first order.

  14. Prediction of ground motion due to mining seismic activity: a general prediction scheme applied to assess impacts on tailings pond in Legnica-Glogow Copper District in Poland in the years 2011-2050

    NASA Astrophysics Data System (ADS)

    Lasocki, S.; Orlecka-Sikora, B.

    2012-04-01

    Copper-ore excavation in the Legnica-Głogow Copper District (LGCD) in south-west Poland is accompanied by intense induced seismic activity. In-mine seismic systems record altogether thousands events annually, whose local magnitude ranges from 0.4 to 4.5. Within a range of mining tremors impact is the Zelazny Most tailings pond, one of the largest waste dumps in the world. To ensure its safety a probabilistic seismic hazard analysis (PSHA) is performed every few years and its results are used to adjust mining plans. In this work we present the newest predictions of limits of ground motion at the Żelazny Most pond embankments for the period 2011-2050. A seismic process in mines is controlled predominantly by time-varying mining works, therefore the results of PSHA for mining induced seismicity are predictions related to a prescribed time period in the future. Here, ground motion has been parameterized by peak horizontal and peak vertical acceleration and the exceedance probability of the limit is 5 per-cent. The work is done in a general prediction scheme. The expected seismic excitation is linked to the continuation of mining in LGCD. Based on mining plans 84 seismic zones, expected to become active in the years 2011-2050, have been identified and their periods of activity have been established. Seismic activity associated with past and current mining works is used to choose alternative models of event rate and event size distribution for the seismicity in the zones of future activity. Analyzing mining seismic catalogs, 188 zones active in the past and/or at present have been singled out and their probabilistic characteristics have been determined. It is assumed that the a priori probability of a model to be followed in a future zone is inversely proportional to the distance between the past zone, which originated the model, and the future active zone. As an epicenter distribution in future zones, the 2D uniform distribution is assumed, supposing that tremors may

  15. A novel symbolization scheme for multichannel recordings with emphasis on phase information and its application to differentiate EEG activity from different mental tasks.

    PubMed

    Dimitriadis, Stavros I; Laskaris, Nikolaos A; Tsirka, Vasso; Erimaki, Sofia; Vourkas, Michael; Micheloyannis, Sifis; Fotopoulos, Spiros

    2012-02-01

    Symbolic dynamics is a powerful tool for studying complex dynamical systems. So far many techniques of this kind have been proposed as a means to analyze brain dynamics, but most of them are restricted to single-sensor measurements. Analyzing the dynamics in a channel-wise fashion is an invalid approach for multisite encephalographic recordings, since it ignores any pattern of coordinated activity that might emerge from the coherent activation of distinct brain areas. We suggest, here, the use of neural-gas algorithm (Martinez et al. in IEEE Trans Neural Netw 4:558-569, 1993) for encoding brain activity spatiotemporal dynamics in the form of a symbolic timeseries. A codebook of k prototypes, best representing the instantaneous multichannel data, is first designed. Each pattern of activity is then assigned to the most similar code vector. The symbolic timeseries derived in this way is mapped to a network, the topology of which encapsulates the most important phase transitions of the underlying dynamical system. Finally, global efficiency is used to characterize the obtained topology. We demonstrate the approach by applying it to EEG-data recorded from subjects while performing mental calculations. By working in a contrastive-fashion, and focusing in the phase aspects of the signals, we show that the underlying dynamics differ significantly in their symbolic representations. The online version of this article (doi:10.1007/s11571-011-9186-5) contains supplementary material, which is available to authorized users.

  16. An Investigation into Nigerian Teachers' Knowledge of Primary Science Curriculum Content and Involvement in Practical Activities: Implications for the UBE Scheme

    ERIC Educational Resources Information Center

    Ogunleye, Ayodele O.

    2009-01-01

    The study was designed to find out the extent of Nigerian teachers' knowledge of primary science curriculum content and their involvement in the participation of their pupils in science activities. Furthermore, the study sought to find out teachers ranking of primary science objectives. The subjects were 60 primary school teachers randomly…

  17. Mittag-Leffler synchronization of delayed fractional-order bidirectional associative memory neural networks with discontinuous activations: state feedback control and impulsive control schemes.

    PubMed

    Ding, Xiaoshuai; Cao, Jinde; Zhao, Xuan; Alsaadi, Fuad E

    2017-08-01

    This paper is concerned with the drive-response synchronization for a class of fractional-order bidirectional associative memory neural networks with time delays, as well as in the presence of discontinuous activation functions. The global existence of solution under the framework of Filippov for such networks is firstly obtained based on the fixed-point theorem for condensing map. Then the state feedback and impulsive controllers are, respectively, designed to ensure the Mittag-Leffler synchronization of these neural networks and two new synchronization criteria are obtained, which are expressed in terms of a fractional comparison principle and Razumikhin techniques. Numerical simulations are presented to validate the proposed methodologies.

  18. A hybrid scheme for encryption and watermarking

    NASA Astrophysics Data System (ADS)

    Xu, Xiaowei; Dexter, Scott D.; Eskicioglu, Ahmet M.

    2004-06-01

    Encryption and watermarking are complementary lines of defense in protecting multimedia content. Recent watermarking techniques have therefore been developed independent from encryption techniques. In this paper, we present a hybrid image protection scheme to establish a relation between the data encryption key and the watermark. Prepositioned secret sharing allows the reconstruction of different encryption keys by communicating different activating shares for the same prepositioned information. Each activating share is used by the receivers to generate a fresh content decryption key. In the proposed scheme, the activating share is used to carry copyright or usage rights data. The bit stream that represents this data is also embedded in the content as a visual watermark. When the encryption key needs to change, the data source generates a new activating share, and embeds the corresponding watermark into the multimedia stream. Before transmission, the composite stream is encrypted with the key constructed from the new activating share. Each receiver can decrypt the stream after reconstructing the same key, and extract the watermark from the image. Our presentation will include the application of the scheme to a test image, and a discussion on the data hiding capacity, watermark transparency, and robustness to common attacks.

  19. Active polar gullies on Mars and the role of carbon dioxide.

    PubMed

    Hoffman, Nick

    2002-01-01

    The detection of geologically recent channels and gullies on Mars has been interpreted as evidence for recent water activity on this arid and cold planet. The presence of active water would have considerable implications for the history of Mars and for the potential for an active near-surface biota; however, water is not the only substance that can flow and may actually be one of the least likely candidates when the modern permafrost environment is considered. Here, a key site of recent gully and channel development on Mars is reported at 71 degrees S in Sisyphi Cavi, within the annual zone of polar CO2 ice and snow accumulation. Superposition of channel features over and/or through the defrosting CO2 snowpack shows that the channels are active at the present day and probably have fluid flows every spring during the annual defrosting. In itself, this is a significant observation as active fluid flows of any nature have not yet been proven on Mars. However, the ambient temperature at the time of gully activity appears to require a role for CO2 in the formation of the channels, rather than water. A model is proposed for gas-lubricated flow in the channels based on avalanching of CO2 snowpack and clastic debris. If similar mechanisms are responsible for all the recent gullies on Mars, then perhaps no near-surface astrobiological targets are available.

  20. Chaotic communication scheme with multiplication

    NASA Astrophysics Data System (ADS)

    Bobreshov, A. M.; Karavaev, A. A.

    2007-05-01

    A new scheme of data transmission with nonlinear admixing is described, in which the two mutually inverse operations (multiplication and division) ensure multiplicative mixing of the informative and chaotic signals that provides a potentially higher degree of security. A special feature of the proposed scheme is the absence of limitations (related to the division by zero) imposed on the types of informative signals.

  1. Plotting and Scheming

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Figure 1 [figure removed for brevity, see original site] Figure 2 Click for larger view

    These two graphics are planning tools used by Mars Exploration Rover engineers to plot and scheme the perfect location to place the rock abrasion tool on the rock collection dubbed 'El Capitan' near Opportunity's landing site. 'El Capitan' is located within a larger outcrop nicknamed 'Opportunity Ledge.'

    The rover visualization team from NASA Ames Research Center, Moffett Field, Calif., initiated the graphics by putting two panoramic camera images of the 'El Capitan' area into their three-dimensional model. The rock abrasion tool team from Honeybee Robotics then used the visualization tool to help target and orient their instrument on the safest and most scientifically interesting locations. The blue circle represents one of two current targets of interest, chosen because of its size, lack of dust, and most of all its distinct and intriguing geologic features. To see the second target location, see the image titled 'Plotting and Scheming.'

    The rock abrasion tool is sensitive to the shape and texture of a rock, and must safely sit within the 'footprint' indicated by the blue circles. The rock area must be large enough to fit the contact sensor and grounding mechanism within the area of the outer blue circle, and the rock must be smooth enough to get an even grind within the abrasion area of the inner blue circle. If the rock abrasion tool were not grounded by its support mechanism or if the surface were uneven, it could 'run away' from its target. The rock abrasion tool is location on the rover's instrument deployment device, or arm.

    Over the next few martian days, or sols, the rover team will use these and newer, similar graphics created with more recent, higher-resolution panoramic camera images and super-spectral data from the miniature thermal emission spectrometer. These data will be used to pick the best

  2. A new flux splitting scheme

    NASA Technical Reports Server (NTRS)

    Liou, Meng-Sing; Steffen, Christopher J., Jr.

    1991-01-01

    A new flux splitting scheme is proposed. The scheme is remarkably simple and yet its accuracy rivals and in some cases surpasses that of Roe's solver in the Euler and Navier-Stokes solutions performed in this study. The scheme is robust and converges as fast as the Roe splitting. An approximately defined cell-face advection Mach number is proposed using values from the two straddling cells via associated characteristic speeds. This interface Mach number is then used to determine the upwind extrapolation for the convective quantities. Accordingly, the name of the scheme is coined as Advection Upstream Splitting Method (AUSM). A new pressure splitting is introduced which is shown to behave successfully, yielding much smoother results than other existing pressure splittings. Of particular interest is the supersonic blunt body problem in which the Roe scheme gives anomalous solutions. The AUSM produces correct solutions without difficulty for a wide range of flow conditions as well as grids.

  3. The impact of revised simplified Arakawa-Schubert scheme on the simulation of mean and diurnal variability associated with active and break phases of Indian summer monsoon using CFSv2

    NASA Astrophysics Data System (ADS)

    Ganai, Malay; Krishna, R. Phani Murali; Mukhopadhyay, P.; Mahakur, M.

    2016-08-01

    The impact of revised simplified Arakawa-Schubert (RSAS) convective parameterization scheme in Climate Forecast System (CFS) version 2 (CFSv2) on the simulation of active and break phases of Indian summer monsoon (ISM) has been investigated. The results revealed that RSAS showed better fidelity in simulating monsoon features from diurnal to daily scales during active and break periods as compared to SAS simulation. Prominent improvement can be noted in simulating diurnal phase of precipitation in RSAS over central India (CI) and equatorial Indian Ocean (EIO) region during active periods. The spatial distribution of precipitation largely improved in RSAS simulation during active and break episodes. CFSv2 with SAS simulation has noticeable dry bias over CI and wet bias over EIO region which appeared to be largely reduced in RSAS simulation during both phases of the intraseasonal oscillation (ISO). During active periods, RSAS simulates more realistic probability distribution function (PDF) in good agreement with the observation. The relative improvement has been identified in outgoing longwave radiation, monsoon circulations, and vertical velocities in RSAS over SAS simulation. The improvement of rainfall distribution appears to be contributed by proper simulation of convective rainfall in RSAS. CFSv2 with RSAS simulation is able to simulate observed diurnal cycle of rainfall over CI. It correctly reproduces the time of maximum rainfall over CI. It is found that the improved feedback between moisture and convective processes in RSAS may be attributed to its improved simulation. Besides improvement, RSAS could not reproduce proper tropospheric temperature, cloud hydrometeors over ISM domain which shows the scope for future development.

  4. Quantum relay schemes for continuous-variable quantum key distribution

    NASA Astrophysics Data System (ADS)

    Guo, Ying; Liao, Qin; Huang, Duan; Zeng, Guihua

    2017-04-01

    We propose several concatenated quantum relay continuous-variable quantum key distribution schemes based on the parametric amplifier (PA) and the beam splitter (BS). Instead of using only one BS in the traditional relay scheme, the proposed schemes provide two operations that involve both PA and BS, activating the beam splitting and recombining operations in turn. These schemes would benefit the system performance improvement by providing signal amplification and establishing quantum correlations. We show that the different effects of the relay schemes will cause different system performances because of the varied signal-to-noise ratio (SNR) of output fields. The system's secret key rate will be increased when equipping with the PA-BS relay scheme, because the output fields of the PA are entangled with the correlated quantum noises while input fields of the BS are superimposed, subsequently leading to the quantum noise reduction of the total output fields of relay station, while the reversed BS-PA relay scheme has little advantage over the traditional counterpart that contains only one BS in relay data postprocessing because it will not cause any SNR improvement. Moreover, the reinforced PA-PA relay scheme results in a slight improvement due to the increased SNR. These quantum relay schemes can be performed through the beam splitting, the recombining operations, and the relay data postprocessing, such that it would be suitable for secret information exchange in complex networks with intermediate stations.

  5. Consistency and Applicability of Parameterization Schemes for Aerosol Size-resolved Activation Ratio based on Field Measurements in the North China Plain.

    NASA Astrophysics Data System (ADS)

    Tao, J.; Zhao, C.

    2016-12-01

    The parameterization of aerosol size-resolved activation ratio (AR) is essential to predict the cloud condensation nulcei (CCN) number concentration (NCCN). The critical issues to the application of the AR parameterization in models are (1) the consistency of the different equations to fit AR curves and (2) the applicability in the estimate of NCCN under different pollution conditions, which were discussed in this study based on the measurements of the aerosol size-resolved AR in summer in the North China Plain. The comparison results of the three kinds of fitting equations demonstrated that both their fitting curves and the variations of their fitting parameters were similar with each other. It was concluded that the consistency of different equations was reached. The commonly used method to calculate NCCN with a fixed AR was found to be accurate except that strong local emissions existed. For the calculation of NCCN under different regional pollution conditions, the representative fitting parameters can be replaced by the campaign averages and good agreements were achieved. NCCN calculation was overestimated by about 10% in the evening when soot emission was abundant and deviated from 1:1 line by 15% during New Particle Formation (NPF) events in the afternoon. The bias of the calculated NCCN due to the significant local emissions can not be eliminated by using the representative fitting parameters and under these circumstance the accurate prediction of NCCN required the on-line information of aerosol hygroscopicity.This research will improve the quantification of the aerosol indirect effect in models.

  6. 1550 nm VCSEL-based 0.48 Tb/s transmission scheme employing PAM-4 and WDM for active optical cables

    NASA Astrophysics Data System (ADS)

    Markou, S.; Dris, S.; Kalavrouziotis, D.; Avramopoulos, H.; Pleros, N.; Tsiokos, Dimitris M.

    2014-05-01

    With this paper we investigate the system-level performance of VCSELs, parameterized with true experimental LI-VI data and dynamic characteristics of state-of-the-art VCSELs with 3 dB modulation bandwidth at 15 GHz, and propose their deployment as high-speed multi-level optical sources in a mid-range active optical cable (AOC) model for performance prediction of a rack-to-rack interconnection. The AOC architecture combines a 6-element 1550 nm VCSEL array, each directly modulated with 40 Gbaud PAM-4 data, with a wavelength division multiplexer (WDM), in order to implement a parallel link with aggregate traffic of 0.48 Tb/s. Transmission reach exceeded 300 m by deploying a two-tap feed forward equalizer filter at the electrical VCSEL driver. Bit Error Rate (BER) measurements and analysis were carried out in MATLAB. In practice, the thermal behavior and basic operational characteristics of the VCSELs fabricated by the Technische Universität München (TUM) were used to study the thermal performance and operational range of the complete AOC model. The VCSELs were initially operated at 20°C and BER measurements showed power penalties of 1.7 dB and 3.5 dB at 300 m and 500 m of transmission distance respectively for all 6 data channels. System performance was also investigated for elevated operating temperatures of the VCSEL module and the additional system degradation and BER penalties introduced by operation at 50°C and 65°C were also investigated for transmission distances of 300 m and 500 m.

  7. [Modern scheme for the diagnosis of staphylococci].

    PubMed

    Skalka, B

    1985-08-01

    A simplified scheme for the subdivision of coagulase-positive staphylococci and another simplified scheme for the diagnostics of coagulase-negative species were worked out. On the basis of the production of staphylokinase, coagulation of human and bovine plasma, acetoin production from glucose, and growth on agar with crystal violet, it is possible to identify S. aureus with its biovars A, B, C1, C2, D, as well as S. intermedius. The coagulase-negative species can be diagnosed according to their sensitivity to novobiocin, nitrate reduction, fermentation of maltose, sucrose, salicin, xylose, trehalose, mannitol and mannose, and haemolytic activity. The proposed diagnostic schemes were verified with success on the collection strains and on the 1305 staphylococci strains isolated largely from the bovine mammary gland, from dogs, man and domestic fowl. In S. aureus strains a close correlation was demonstrated between their biotype characteristics and the host species. A similar correlation was determined for S. intermedius. As to the coagulase-negative species, S. epidermidis, S. hominis and S. haemolyticus were diagnosed most frequently. Both schemes represent a reliable, prompt and technically simple method of the diagnostics of the Staphylococcus microorganisms.

  8. Seyfert galaxies and ``Unified Scheme''

    NASA Astrophysics Data System (ADS)

    Pashchenko, I. N.; Pilipenko, S. V.; Vitrishchak, V. M.

    2011-01-01

    From spectroscopic point of view Seyfert galaxies (as other Active Galactic Nuclei --- AGN) basically are subdivided into two types: with and without broad permitted emission lines in their optical spectra (so called type I and type II Seyfert galaxies or AGNs). One of the most fundumental idea concerning AGN is that observed AGN type (I or II) is determined by inclination angle of AGN to the line of sight (LOS). At high inclination angles LOS crosses dusty torus which absorbs and scatters line emission. But in some recent papers the differences in close (<100 kpc) environment of SyI and SyII (SyII have more close companions), which are incompatible with Unification Scheme, were found and the possibility of physical (intrinsic) differences between Seyfert I and II was discussed. It was shown that this difference could be due to selection effects caused by the sample criteria. We sampled SyI and SyII galaxies from the Sloan Digital Sky Survey (SDSS) on the basis of their emission line properties thus excluding selection and discuss the properties of the environment of Seyfert galaxies.

  9. Relaxation schemes for Chebyshev spectral multigrid methods

    NASA Technical Reports Server (NTRS)

    Kang, Yimin; Fulton, Scott R.

    1993-01-01

    Two relaxation schemes for Chebyshev spectral multigrid methods are presented for elliptic equations with Dirichlet boundary conditions. The first scheme is a pointwise-preconditioned Richardson relaxation scheme and the second is a line relaxation scheme. The line relaxation scheme provides an efficient and relatively simple approach for solving two-dimensional spectral equations. Numerical examples and comparisons with other methods are given.

  10. Active alignment scheme for the MPTS array

    SciTech Connect

    Iwasaki, R.

    1980-01-01

    In order to maximize the efficiency of the microwave power transmission system (MPTS), the surface of the array antenna must be extremely flat, which is difficult to achieve using passive techniques over the 1 km dimensions of the array. In order to achieve and maintain this required flatness, a rotating laser beam used for leveling applications on earth has been utilized as a reference system. A photoconductive sensor with a reflective collecting surface is used to determine the displacement and polarity of any misalignment and automatically engage a stepping motor to drive a variable-length mechanism to make the necessary corrections. A three-point subarray alignment arrangement is described which independently adjusts, in the three orthogonal directions, the height and tilt of subarrays within the MPTS array and readily adapts to any physical distortions of the secondary structure (such as that resulting from severe temperature extremes caused by an eclipse of the sun.

  11. A finite element simulation scheme for biological muscular hydrostats.

    PubMed

    Liang, Y; McMeeking, R M; Evans, A G

    2006-09-07

    An explicit finite element scheme is developed for biological muscular hydrostats such as squid tentacles, octopus arms and elephant trunks. The scheme is implemented by embedding muscle fibers in finite elements. In any given element, the fiber orientation can be assigned arbitrarily and multiple muscle directions can be simulated. The mechanical stress in each muscle fiber is the sum of active and passive parts. The active stress is taken to be a function of activation state, muscle fiber shortening velocity and fiber strain; while the passive stress depends only on the strain. This scheme is tested by simulating extension of a squid tentacle during prey capture; our numerical predictions are in close correspondence with existing experimental results. It is shown that the present finite element scheme can successfully simulate more complex behaviors such as torsion of a squid tentacle and the bending behavior of octopus arms or elephant trunks.

  12. The Influence of Second-Hand Cigarette Smoke Exposure during Childhood and Active Cigarette Smoking on Crohn’s Disease Phenotype Defined by the Montreal Classification Scheme in a Western Cape Population, South Africa

    PubMed Central

    Chivese, Tawanda; Esterhuizen, Tonya M.; Basson, Abigail Raffner

    2015-01-01

    Background Smoking may worsen the disease outcomes in patients with Crohn’s disease (CD), however the effect of exposure to second-hand cigarette smoke during childhood is unclear. In South Africa, no such literature exists. The aim of this study was to investigate whether disease phenotype, at time of diagnosis of CD, was associated with exposure to second-hand cigarette during childhood and active cigarette smoking habits. Methods A cross sectional examination of all consecutive CD patients seen during the period September 2011-January 2013 at 2 large inflammatory bowel disease centers in the Western Cape, South Africa was performed. Data were collected via review of patient case notes, interviewer-administered questionnaire and clinical examination by the attending gastroenterologist. Disease phenotype (behavior and location) was evaluated at time of diagnosis, according to the Montreal Classification scheme. In addition, disease behavior was stratified as ‘complicated’ or ‘uncomplicated’, using predefined definitions. Passive cigarette smoke exposure was evaluated during 3 age intervals: 0–5, 6–10, and 11–18 years. Results One hundred and ninety four CD patients were identified. Cigarette smoking during the 6 months prior to, or at time of diagnosis was significantly associated with ileo-colonic (L3) disease (RRR = 3.63; 95%CI, 1.32–9.98, p = 0.012) and ileal (L1) disease (RRR = 3.54; 95%CI, 1.06–11.83, p = 0.040) compared with colonic disease. In smokers, childhood passive cigarette smoke exposure during the 0–5 years age interval was significantly associated with ileo-colonic CD location (RRR = 21.3; 95%CI, 1.16–391.55, p = 0.040). No significant association between smoking habits and disease behavior at diagnosis, whether defined by the Montreal scheme, or stratified as ‘complicated’ vs ‘uncomplicated’, was observed. Conclusion Smoking habits were associated with ileo-colonic (L3) and ileal (L1) disease at time of diagnosis in

  13. High resolution schemes for hyperbolic conservation laws

    NASA Technical Reports Server (NTRS)

    Harten, A.

    1983-01-01

    A class of new explicit second order accurate finite difference schemes for the computation of weak solutions of hyperbolic conservation laws is presented. These highly nonlinear schemes are obtained by applying a nonoscillatory first order accurate scheme to an appropriately modified flux function. The so-derived second order accurate schemes achieve high resolution while preserving the robustness of the original nonoscillatory first order accurate scheme. Numerical experiments are presented to demonstrate the performance of these new schemes.

  14. Active surveillance scheme in three Romanian hospitals reveals a high prevalence and variety of carbapenamase-producing Gram-negative bacteria: a pilot study, December 2014 to May 2015.

    PubMed

    Timofte, Dorina; Panzaru, Carmen Valentina; Maciuca, Iuliana Elena; Dan, Maria; Mare, Anca Delia; Man, Adrian; Toma, Felicia

    2016-06-23

    We report the findings of an active surveillance scheme for detection of asymptomatic carriers with carbapenemase-producing Gram-negative bacteria (CP-GNB) in Romanian hospitals. During a pilot study from December 2014 to May 2015, faecal cultures were screened in three hospitals (two large, one medium-size) for patients newly admitted to selected wards or inpatients transferred from other wards to an intensive-care unit. The study revealed a high prevalence of CP-GNB detected in 22/27 and 28/38 of the carbapenem non-susceptible isolates from Hospitals 1 and 3, respectively. CP-GNB identified through faecal screening included NDM-1-producing Serratia marcescens and Klebsiella pneumoniae, OXA-48-producing K. pneumoniae and OXA-23-producing Acinetobacter baumannii. The distribution of the CP-GNB varied between the hospitals, with NDM-1-producing S. marcescens and K. pneumoniae being prevalent in the north-central part of the country and OXA-23/24-producing A. baumannii, OXA-48-producing K.pneumoniae, Morganella morganii and VIM-2-producing Escherichia coli/Pseudomonas aeruginosa detected in the north-east of the country. Conjugation studies showed that carbapenem resistance was transferable and PCR-based replicon typing identified blaNDM-1 on IncFIIs in S. marcescens and K. pneumoniae from Hospital 1 and blaOXA-48 on IncL plasmids in all Klebsiella spp. isolates from Hospitals 1 and 3. Our findings underline the importance of active surveillance for detection of CP-GNB asymptomatic faecal carriers and suggest a likely endemic spread of CP-GNB in Romania. This article is copyright of The Authors, 2016.

  15. Development of a numerical scheme to predict geomagnetic storms after intense solar events and geomagnetic activity 27 days in advance. Final report, 6 Aug 86-16 Nov 90

    SciTech Connect

    Akasofu, S.I.; Lee, L.H.

    1991-02-01

    The modern geomagnetic storm prediction scheme should be based on a numerical simulation method, rather than on a statistical result. Furthermore, the scheme should be able to predict the geomagnetic storm indices, such as the Dst and AE indices, as a function of time. By recognizing that geomagnetic storms are powered by the solar wind-magnetosphere generator and that its power is given in terms of the solar wind speed, the interplanetary magnetic field (IMF) magnitude and polar angle, the authors have made a major advance in predicting both flare-induced storms and recurrent storms. Furthermore, it is demonstrated that the prediction scheme can be calibrated using the interplanetary scintillation (IPS) observation, when the solar disturbance advances about half-way to the earth. It is shown, however, that we are still far from a reliable prediction scheme. The prediction of the IMF polar angle requires future advance in understanding characteristics of magnetic clouds.

  16. Optimal probabilistic dense coding schemes

    NASA Astrophysics Data System (ADS)

    Kögler, Roger A.; Neves, Leonardo

    2017-04-01

    Dense coding with non-maximally entangled states has been investigated in many different scenarios. We revisit this problem for protocols adopting the standard encoding scheme. In this case, the set of possible classical messages cannot be perfectly distinguished due to the non-orthogonality of the quantum states carrying them. So far, the decoding process has been approached in two ways: (i) The message is always inferred, but with an associated (minimum) error; (ii) the message is inferred without error, but only sometimes; in case of failure, nothing else is done. Here, we generalize on these approaches and propose novel optimal probabilistic decoding schemes. The first uses quantum-state separation to increase the distinguishability of the messages with an optimal success probability. This scheme is shown to include (i) and (ii) as special cases and continuously interpolate between them, which enables the decoder to trade-off between the level of confidence desired to identify the received messages and the success probability for doing so. The second scheme, called multistage decoding, applies only for qudits ( d-level quantum systems with d>2) and consists of further attempts in the state identification process in case of failure in the first one. We show that this scheme is advantageous over (ii) as it increases the mutual information between the sender and receiver.

  17. Nonlinear Secret Image Sharing Scheme

    PubMed Central

    Shin, Sang-Ho; Yoo, Kee-Young

    2014-01-01

    Over the past decade, most of secret image sharing schemes have been proposed by using Shamir's technique. It is based on a linear combination polynomial arithmetic. Although Shamir's technique based secret image sharing schemes are efficient and scalable for various environments, there exists a security threat such as Tompa-Woll attack. Renvall and Ding proposed a new secret sharing technique based on nonlinear combination polynomial arithmetic in order to solve this threat. It is hard to apply to the secret image sharing. In this paper, we propose a (t, n)-threshold nonlinear secret image sharing scheme with steganography concept. In order to achieve a suitable and secure secret image sharing scheme, we adapt a modified LSB embedding technique with XOR Boolean algebra operation, define a new variable m, and change a range of prime p in sharing procedure. In order to evaluate efficiency and security of proposed scheme, we use the embedding capacity and PSNR. As a result of it, average value of PSNR and embedding capacity are 44.78 (dB) and 1.74t⌈log2⁡m⌉ bit-per-pixel (bpp), respectively. PMID:25140334

  18. Nonlinear secret image sharing scheme.

    PubMed

    Shin, Sang-Ho; Lee, Gil-Je; Yoo, Kee-Young

    2014-01-01

    Over the past decade, most of secret image sharing schemes have been proposed by using Shamir's technique. It is based on a linear combination polynomial arithmetic. Although Shamir's technique based secret image sharing schemes are efficient and scalable for various environments, there exists a security threat such as Tompa-Woll attack. Renvall and Ding proposed a new secret sharing technique based on nonlinear combination polynomial arithmetic in order to solve this threat. It is hard to apply to the secret image sharing. In this paper, we propose a (t, n)-threshold nonlinear secret image sharing scheme with steganography concept. In order to achieve a suitable and secure secret image sharing scheme, we adapt a modified LSB embedding technique with XOR Boolean algebra operation, define a new variable m, and change a range of prime p in sharing procedure. In order to evaluate efficiency and security of proposed scheme, we use the embedding capacity and PSNR. As a result of it, average value of PSNR and embedding capacity are 44.78 (dB) and 1.74t⌈log2 m⌉ bit-per-pixel (bpp), respectively.

  19. Simple scheme for gauge mediation

    SciTech Connect

    Murayama, Hitoshi; Nomura, Yasunori

    2007-05-01

    We present a simple scheme for constructing models that achieve successful gauge mediation of supersymmetry breaking. In addition to our previous work [H. Murayama and Y. Nomura, Phys. Rev. Lett. 98, 151803 (2007)] that proposed drastically simplified models using metastable vacua of supersymmetry breaking in vectorlike theories, we show there are many other successful models using various types of supersymmetry-breaking mechanisms that rely on enhanced low-energy U(1){sub R} symmetries. In models where supersymmetry is broken by elementary singlets, one needs to assume U(1){sub R} violating effects are accidentally small, while in models where composite fields break supersymmetry, emergence of approximate low-energy U(1){sub R} symmetries can be understood simply on dimensional grounds. Even though the scheme still requires somewhat small parameters to sufficiently suppress gravity mediation, we discuss their possible origins due to dimensional transmutation. The scheme accommodates a wide range of the gravitino mass to avoid cosmological problems.

  20. One-qubit fingerprinting schemes

    SciTech Connect

    Beaudrap, J. Niel de

    2004-02-01

    Fingerprinting is a technique in communication complexity in which two parties (Alice and Bob) with large data sets send short messages to a third party (a referee), who attempts to compute some function of the larger data sets. For the equality function, the referee attempts to determine whether Alice's data and Bob's data are the same. In this paper, we consider the extreme scenario of performing fingerprinting where Alice and Bob both send either one bit (classically) or one qubit (in the quantum regime) messages to the referee for the equality problem. Restrictive bounds are demonstrated for the error probability of one-bit fingerprinting schemes, and show that it is easy to construct one-qubit fingerprinting schemes which can outperform any one-bit fingerprinting scheme. The author hopes that this analysis will provide results useful for performing physical experiments, which may help to advance implementations for more general quantum communication protocols.

  1. New evaluation method for ARQ schemes

    NASA Astrophysics Data System (ADS)

    Nakamura, M.; Kodama, T.

    1988-10-01

    Automatic-repeat-request (ARQ) schemes which provide high system reliability with simple error control are widely used in data communication systems. A new evaluation method for ARQ schemes is presented which makes it possible to compare performances for various error-control schemes. Numerical results are reported for error correction, pure ARQ, and hybrid ARQ schemes.

  2. The inclusion problem for monadic recursion schemes

    NASA Technical Reports Server (NTRS)

    Friedman, E. P.

    1973-01-01

    The inclusion problem for the class of monadic recursion schemes is shown to be undecidable. The proof illustrates the close relationship between monadic recursion schemes and deterministic pushdown automata. The proof is extended to show that both the weak equivalence problem for the class of monadic recursion schemes and the weak equivalence problem for the class of free schemes without identity are undecidable.

  3. Hybrid scheme for heavy flavors: Merging the fixed flavor number scheme and variable flavor number scheme

    NASA Astrophysics Data System (ADS)

    Kusina, A.; Olness, F. I.; Schienbein, I.; Ježo, T.; Kovařík, K.; Stavreva, T.; Yu, J. Y.

    2013-10-01

    We introduce a hybrid variable flavor number scheme for heavy flavors, denoted H-VFNS, which incorporates the advantages of both the traditional variable flavor number scheme as well as the fixed flavor number scheme (FFNS). By including an explicit NF dependence in both the parton distribution functions (PDFs) and the strong coupling constant αS, we generate coexisting sets of PDFs and αS for NF={3,4,5,6} at any scale μ that are related analytically by the MS¯ matching conditions. The H-VFNS resums the heavy quark contributions and provides the freedom to choose the optimal NF for each particular data set. Thus, we can fit selected HERA data in a FFNS framework, while retaining the benefits of the VFNS to analyze LHC data at high scales. We illustrate how such a fit can be implemented for the case of both HERA and LHC data.

  4. On symmetric and upwind TVD schemes

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    1985-01-01

    A class of explicit and implicit total variation diminishing (TVD) schemes for the compressible Euler and Navier-Stokes equations was developed. They do not generate spurious oscillations across shocks and contact discontinuities. In general, shocks can be captured within 1 to 2 grid points. For the inviscid case, these schemes are divided into upwind TVD schemes and symmetric (nonupwind) TVD schemes. The upwind TVD scheme is based on the second-order TVD scheme. The symmetric TVD scheme is a generalization of Roe's and Davis' TVD Lax-Wendroff scheme. The performance of these schemes on some viscous and inviscid airfoil steady-state calculations is investigated. The symmetric and upwind TVD schemes are compared.

  5. A dynamic identity based authentication scheme using chaotic maps for telecare medicine information systems.

    PubMed

    Wang, Zhiheng; Huo, Zhanqiang; Shi, Wenbo

    2015-01-01

    With rapid development of computer technology and wide use of mobile devices, the telecare medicine information system has become universal in the field of medical care. To protect patients' privacy and medial data's security, many authentication schemes for the telecare medicine information system have been proposed. Due to its better performance, chaotic maps have been used in the design of authentication schemes for the telecare medicine information system. However, most of them cannot provide user's anonymity. Recently, Lin proposed a dynamic identity based authentication scheme using chaotic maps for the telecare medicine information system and claimed that their scheme was secure against existential active attacks. In this paper, we will demonstrate that their scheme cannot provide user anonymity and is vulnerable to the impersonation attack. Further, we propose an improved scheme to fix security flaws in Lin's scheme and demonstrate the proposed scheme could withstand various attacks.

  6. Invisibly Sanitizable Digital Signature Scheme

    NASA Astrophysics Data System (ADS)

    Miyazaki, Kunihiko; Hanaoka, Goichiro; Imai, Hideki

    A digital signature does not allow any alteration of the document to which it is attached. Appropriate alteration of some signed documents, however, should be allowed because there are security requirements other than the integrity of the document. In the disclosure of official information, for example, sensitive information such as personal information or national secrets is masked when an official document is sanitized so that its nonsensitive information can be disclosed when it is requested by a citizen. If this disclosure is done digitally by using the current digital signature schemes, the citizen cannot verify the disclosed information because it has been altered to prevent the leakage of sensitive information. The confidentiality of official information is thus incompatible with the integrity of that information, and this is called the digital document sanitizing problem. Conventional solutions such as content extraction signatures and digitally signed document sanitizing schemes with disclosure condition control can either let the sanitizer assign disclosure conditions or hide the number of sanitized portions. The digitally signed document sanitizing scheme we propose here is based on the aggregate signature derived from bilinear maps and can do both. Moreover, the proposed scheme can sanitize a signed document invisibly, that is, no one can distinguish whether the signed document has been sanitized or not.

  7. Upwind Compact Finite Difference Schemes

    NASA Astrophysics Data System (ADS)

    Christie, I.

    1985-07-01

    It was shown by Ciment, Leventhal, and Weinberg ( J. Comput. Phys.28 (1978), 135) that the standard compact finite difference scheme may break down in convection dominated problems. An upwinding of the method, which maintains the fourth order accuracy, is suggested and favorable numerical results are found for a number of test problems.

  8. A New Improving Quantum Secret Sharing Scheme

    NASA Astrophysics Data System (ADS)

    Xu, Ting-Ting; Li, Zhi-Hui; Bai, Chen-Ming; Ma, Min

    2017-01-01

    An improving quantum secret sharing scheme (IQSS scheme) was introduced by Nascimento et al. (Phys. Rev. A 64, 042311 (2001)), which was analyzed by the improved quantum access structure. In this paper, we propose a new improving quantum secret sharing scheme, and more quantum access structures can be realized by this scheme than the previous one. For example, we prove that any threshold and hypercycle quantum access structures can be realized by the new scheme.

  9. A New Improving Quantum Secret Sharing Scheme

    NASA Astrophysics Data System (ADS)

    Xu, Ting-Ting; Li, Zhi-Hui; Bai, Chen-Ming; Ma, Min

    2017-04-01

    An improving quantum secret sharing scheme (IQSS scheme) was introduced by Nascimento et al. (Phys. Rev. A 64, 042311 (2001)), which was analyzed by the improved quantum access structure. In this paper, we propose a new improving quantum secret sharing scheme, and more quantum access structures can be realized by this scheme than the previous one. For example, we prove that any threshold and hypercycle quantum access structures can be realized by the new scheme.

  10. 9 CFR 590.538 - Defrosting facilities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... constructed so as to permit ready and thorough cleaning shall be provided. (b) Frozen egg crushers, when used, shall be of approved metal construction. The crushers shall permit ready and thorough cleaning and...

  11. 9 CFR 590.538 - Defrosting facilities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... constructed so as to permit ready and thorough cleaning shall be provided. (b) Frozen egg crushers, when used, shall be of approved metal construction. The crushers shall permit ready and thorough cleaning and...

  12. 9 CFR 590.539 - Defrosting operations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... condition and odor just prior to being emptied into the crusher or receiving tank. Frozen eggs which have... shall be used in handling containers and removing egg product. (f) Crushers and other equipment used in.... (1) Where crushers are used intermittently, they shall be flushed after each use and again...

  13. 9 CFR 590.538 - Defrosting facilities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... constructed so as to permit ready and thorough cleaning shall be provided. (b) Frozen egg crushers, when used, shall be of approved metal construction. The crushers shall permit ready and thorough cleaning and...

  14. 9 CFR 590.538 - Defrosting facilities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... constructed so as to permit ready and thorough cleaning shall be provided. (b) Frozen egg crushers, when used, shall be of approved metal construction. The crushers shall permit ready and thorough cleaning and...

  15. 9 CFR 590.538 - Defrosting facilities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... constructed so as to permit ready and thorough cleaning shall be provided. (b) Frozen egg crushers, when used, shall be of approved metal construction. The crushers shall permit ready and thorough cleaning and...

  16. Subranging scheme for SQUID sensors

    NASA Technical Reports Server (NTRS)

    Penanen, Konstantin I. (Inventor)

    2008-01-01

    A readout scheme for measuring the output from a SQUID-based sensor-array using an improved subranging architecture that includes multiple resolution channels (such as a coarse resolution channel and a fine resolution channel). The scheme employs a flux sensing circuit with a sensing coil connected in series to multiple input coils, each input coil being coupled to a corresponding SQUID detection circuit having a high-resolution SQUID device with independent linearizing feedback. A two-resolution configuration (course and fine) is illustrated with a primary SQUID detection circuit for generating a fine readout, and a secondary SQUID detection circuit for generating a course readout, both having feedback current coupled to the respective SQUID devices via feedback/modulation coils. The primary and secondary SQUID detection circuits function and derive independent feedback. Thus, the SQUID devices may be monitored independently of each other (and read simultaneously) to dramatically increase slew rates and dynamic range.

  17. Cambridge community Optometry Glaucoma Scheme.

    PubMed

    Keenan, Jonathan; Shahid, Humma; Bourne, Rupert R; White, Andrew J; Martin, Keith R

    2015-04-01

    With a higher life expectancy, there is an increased demand for hospital glaucoma services in the United Kingdom. The Cambridge community Optometry Glaucoma Scheme (COGS) was initiated in 2010, where new referrals for suspected glaucoma are evaluated by community optometrists with a special interest in glaucoma, with virtual electronic review and validation by a consultant ophthalmologist with special interest in glaucoma. 1733 patients were evaluated by this scheme between 2010 and 2013. Clinical assessment is performed by the optometrist at a remote site. Goldmann applanation tonometry, pachymetry, monoscopic colour optic disc photographs and automated Humphrey visual field testing are performed. A clinical decision is made as to whether a patient has glaucoma or is a suspect, and referred on or discharged as a false positive referral. The clinical findings, optic disc photographs and visual field test results are transmitted electronically for virtual review by a consultant ophthalmologist. The number of false positive referrals from initial referral into the scheme. Of the patients, 46.6% were discharged at assessment and a further 5.7% were discharged following virtual review. Of the patients initially discharged, 2.8% were recalled following virtual review. Following assessment at the hospital, a further 10.5% were discharged after a single visit. The COGS community-based glaucoma screening programme is a safe and effective way of evaluating glaucoma referrals in the community and reducing false-positive referrals for glaucoma into the hospital system. © 2014 Royal Australian and New Zealand College of Ophthalmologists.

  18. An Arbitrated Quantum Signature Scheme without Entanglement*

    NASA Astrophysics Data System (ADS)

    Li, Hui-Ran; Luo, Ming-Xing; Peng, Dai-Yuan; Wang, Xiao-Jun

    2017-09-01

    Several quantum signature schemes are recently proposed to realize secure signatures of quantum or classical messages. Arbitrated quantum signature as one nontrivial scheme has attracted great interests because of its usefulness and efficiency. Unfortunately, previous schemes cannot against Trojan horse attack and DoS attack and lack of the unforgeability and the non-repudiation. In this paper, we propose an improved arbitrated quantum signature to address these secure issues with the honesty arbitrator. Our scheme takes use of qubit states not entanglements. More importantly, the qubit scheme can achieve the unforgeability and the non-repudiation. Our scheme is also secure for other known quantum attacks.

  19. A biometric signcryption scheme without bilinear pairing

    NASA Astrophysics Data System (ADS)

    Wang, Mingwen; Ren, Zhiyuan; Cai, Jun; Zheng, Wentao

    2013-03-01

    How to apply the entropy in biometrics into the encryption and remote authentication schemes to simplify the management of keys is a hot research area. Utilizing Dodis's fuzzy extractor method and Liu's original signcryption scheme, a biometric identity based signcryption scheme is proposed in this paper. The proposed scheme is more efficient than most of the previous proposed biometric signcryption schemes for that it does not need bilinear pairing computation and modular exponentiation computation which is time consuming largely. The analysis results show that under the CDH and DL hard problem assumption, the proposed scheme has the features of confidentiality and unforgeability simultaneously.

  20. An enhanced biometric authentication scheme for telecare medicine information systems with nonce using chaotic hash function.

    PubMed

    Das, Ashok Kumar; Goswami, Adrijit

    2014-06-01

    Recently, Awasthi and Srivastava proposed a novel biometric remote user authentication scheme for the telecare medicine information system (TMIS) with nonce. Their scheme is very efficient as it is based on efficient chaotic one-way hash function and bitwise XOR operations. In this paper, we first analyze Awasthi-Srivastava's scheme and then show that their scheme has several drawbacks: (1) incorrect password change phase, (2) fails to preserve user anonymity property, (3) fails to establish a secret session key beween a legal user and the server, (4) fails to protect strong replay attack, and (5) lacks rigorous formal security analysis. We then a propose a novel and secure biometric-based remote user authentication scheme in order to withstand the security flaw found in Awasthi-Srivastava's scheme and enhance the features required for an idle user authentication scheme. Through the rigorous informal and formal security analysis, we show that our scheme is secure against possible known attacks. In addition, we simulate our scheme for the formal security verification using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool and show that our scheme is secure against passive and active attacks, including the replay and man-in-the-middle attacks. Our scheme is also efficient as compared to Awasthi-Srivastava's scheme.

  1. Community health insurance schemes & patient satisfaction - evidence from India

    PubMed Central

    Devadasan, N.; Criel, Bart; Damme, Wim Van; Lefevre, Pierre; Manoharan, S.; der Stuyft, Patrick Van

    2011-01-01

    Background & objectives: Quality of care is an important determinant for utilizing health services. In India, the quality of care in most health services is poor. The government recognizes this and has been working on both supply and demand aspects. In particular, it is promoting community health insurance (CHI) schemes, so that patients can access quality services. This observational study was undertaken to measure the level of satisfaction among insured and uninsured patients in two CHI schemes in India. Methods: Patient satisfaction was measured, which is an outcome of good quality care. Two CHI schemes, Action for Community Organisation, Rehabilitation and Development (ACCORD) and Kadamalai Kalanjiam Vattara Sangam (KKVS), were chosen. Randomly selected, insured and uninsured households were interviewed. The household where a patient was admitted to a hospital was interviewed in depth about the health seeking behaviour, the cost of treatment and the satisfaction levels. Results: It was found that at both ACCORD and KKVS, there was no significant difference in the levels of satisfaction between the insured and uninsured patients. The main reasons for satisfaction were the availability of doctors and medicines and the recovery by the patient. Interpretation & conclusions: Our study showed that insured hospitalized patients did not have significantly higher levels of satisfaction compared to uninsured hospitalized patients. If CHI schemes want to improve the quality of care for their clients, so that they adhere to the scheme, the scheme managers need to negotiate actively for better quality of care with empanelled providers. PMID:21321418

  2. Decoupling schemes for the SSC Collider

    SciTech Connect

    Cai, Y.; Bourianoff, G.; Cole, B.; Meinke, R.; Peterson, J.; Pilat, F.; Stampke, S.; Syphers, M.; Talman, R.

    1993-05-01

    A decoupling system is designed for the SSC Collider. This system can accommodate three decoupling schemes by using 44 skew quadrupoles in the different configurations. Several decoupling schemes are studied and compared in this paper.

  3. Comparative study of numerical schemes of TVD3, UNO3-ACM and optimized compact scheme

    NASA Technical Reports Server (NTRS)

    Lee, Duck-Joo; Hwang, Chang-Jeon; Ko, Duck-Kon; Kim, Jae-Wook

    1995-01-01

    Three different schemes are employed to solve the benchmark problem. The first one is a conventional TVD-MUSCL (Monotone Upwind Schemes for Conservation Laws) scheme. The second scheme is a UNO3-ACM (Uniformly Non-Oscillatory Artificial Compression Method) scheme. The third scheme is an optimized compact finite difference scheme modified by us: the 4th order Runge Kutta time stepping, the 4th order pentadiagonal compact spatial discretization with the maximum resolution characteristics. The problems of category 1 are solved by using the second (UNO3-ACM) and third (Optimized Compact) schemes. The problems of category 2 are solved by using the first (TVD3) and second (UNO3-ACM) schemes. The problem of category 5 is solved by using the first (TVD3) scheme. It can be concluded from the present calculations that the Optimized Compact scheme and the UN03-ACM show good resolutions for category 1 and category 2 respectively.

  4. Comparative study of numerical schemes of TVD3, UNO3-ACM and optimized compact scheme

    NASA Technical Reports Server (NTRS)

    Lee, Duck-Joo; Hwang, Chang-Jeon; Ko, Duck-Kon; Kim, Jae-Wook

    1995-01-01

    Three different schemes are employed to solve the benchmark problem. The first one is a conventional TVD-MUSCL (Monotone Upwind Schemes for Conservation Laws) scheme. The second scheme is a UNO3-ACM (Uniformly Non-Oscillatory Artificial Compression Method) scheme. The third scheme is an optimized compact finite difference scheme modified by us: the 4th order Runge Kutta time stepping, the 4th order pentadiagonal compact spatial discretization with the maximum resolution characteristics. The problems of category 1 are solved by using the second (UNO3-ACM) and third (Optimized Compact) schemes. The problems of category 2 are solved by using the first (TVD3) and second (UNO3-ACM) schemes. The problem of category 5 is solved by using the first (TVD3) scheme. It can be concluded from the present calculations that the Optimized Compact scheme and the UN03-ACM show good resolutions for category 1 and category 2 respectively.

  5. Current terminology and diagnostic classification schemes.

    PubMed

    Okeson, J P

    1997-01-01

    This article reviews the current terminology and classification schemes available for temporomandibular disorders. The origin of each term is presented, and the classification schemes that have been offered for temporomandibular disorders are briefly reviewed. Several important classifications are presented in more detail, with mention of advantages and disadvantages. Final recommendations are provided for future direction in the area of classification schemes.

  6. Impacts of Rotation Schemes on Ground-Dwelling Beneficial Arthropods.

    PubMed

    Dunbar, Mike W; Gassmann, Aaron J; O'Neal, Matthew E

    2016-10-01

    Crop rotation alters agroecosystem diversity temporally, and increasing the number of crops in rotation schemes can increase crop yields and reduce reliance on pesticides. We hypothesized that increasing the number of crops in annual rotation schemes would positively affect ground-dwelling beneficial arthropod communities. During 2012 and 2013, pitfall traps were used to measure activity-density and diversity of ground-dwelling communities within three previously established, long-term crop rotation studies located in Wisconsin and Illinois. Rotation schemes sampled included continuous corn, a 2-yr annual rotation of corn and soybean, and a 3-yr annual rotation of corn, soybean, and wheat. Insects captured were identified to family, and non-insect arthropods were identified to class, order, or family, depending upon the taxa. Beneficial arthropods captured included natural enemies, granivores, and detritivores. The beneficial community from continuous corn plots was significantly more diverse compared with the community in the 2-yr rotation, whereas the community in the 3-yr rotation did not differ from either rotation scheme. The activity-density of the total community and any individual taxa did not differ among rotation schemes in either corn or soybean. Crop species within all three rotation schemes were annual crops, and are associated with agricultural practices that make infield habitat subject to anthropogenic disturbances and temporally unstable. Habitat instability and disturbance can limit the effectiveness and retention of beneficial arthropods, including natural enemies, granivores, and detritivores. Increasing non-crop and perennial species within landscapes in conjunction with more diverse rotation schemes may increase the effect of biological control of pests by natural enemies.

  7. Update on the Pyramid Scheme

    NASA Astrophysics Data System (ADS)

    Banks, Tom; Torres, T. J.

    2012-10-01

    We summarize recent work in which we attempt to make consistent models of LHC physics, from the Pyramid Scheme. The models share much with the NMSSM, in particular, enhanced tree level contributions to the Higgs mass and a preference for small tan β. There are three different singlet fields, and a new strongly coupled gauge theory, so the constraints of perturbative unification are quite different. We outline our general approach to the model, which contains a Kähler potential for three of the low energy fields, which is hard to calculate. Detailed calculations, based on approximations to the Kähler potential, will be presented in a future publication.

  8. Adaptive Optics Metrics & QC Scheme

    NASA Astrophysics Data System (ADS)

    Girard, Julien H.

    2017-09-01

    "There are many Adaptive Optics (AO) fed instruments on Paranal and more to come. To monitor their performances and assess the quality of the scientific data, we have developed a scheme and a set of tools and metrics adapted to each flavour of AO and each data product. Our decisions to repeat observations or not depends heavily on this immediate quality control "zero" (QC0). Atmospheric parameters monitoring can also help predict performances . At the end of the chain, the user must be able to find the data that correspond to his/her needs. In Particular, we address the special case of SPHERE."

  9. An adaptive vector quantization scheme

    NASA Technical Reports Server (NTRS)

    Cheung, K.-M.

    1990-01-01

    Vector quantization is known to be an effective compression scheme to achieve a low bit rate so as to minimize communication channel bandwidth and also to reduce digital memory storage while maintaining the necessary fidelity of the data. However, the large number of computations required in vector quantizers has been a handicap in using vector quantization for low-rate source coding. An adaptive vector quantization algorithm is introduced that is inherently suitable for simple hardware implementation because it has a simple architecture. It allows fast encoding and decoding because it requires only addition and subtraction operations.

  10. 'Just another incentive scheme': a qualitative interview study of a local pay-for-performance scheme for primary care.

    PubMed

    Hackett, Julia; Glidewell, Liz; West, Robert; Carder, Paul; Doran, Tim; Foy, Robbie

    2014-10-25

    A range of policy initiatives have addressed inequalities in healthcare and health outcomes. Local pay-for-performance schemes for primary care have been advocated as means of enhancing clinical ownership of the quality agenda and better targeting local need compared with national schemes such as the UK Quality and Outcomes Framework (QOF). We investigated whether professionals' experience of a local scheme in one English National Health Service (NHS) former primary care trust (PCT) differed from that of the national QOF in relation to the goal of reducing inequalities. We conducted retrospective semi-structured interviews with primary care professionals implementing the scheme and those involved in its development. We purposively sampled practices with varying levels of population socio-economic deprivation and achievement. Interviews explored perceptions of the scheme and indicators, likely mechanisms of influence on practice, perceived benefits and harms, and how future schemes could be improved. We used a framework approach to analysis. Thirty-eight professionals from 16 general practices and six professionals involved in developing local indicators participated. Our findings cover four themes: ownership, credibility of the indicators, influences on behaviour, and exacerbated tensions. We found little evidence that the scheme engendered any distinctive sense of ownership or experiences different from the national scheme. Although the indicators and their evidence base were seldom actively questioned, doubts were expressed about their focus on health promotion given that eventual benefits relied upon patient action and availability of local resources. Whilst practices serving more affluent populations reported status and patient benefit as motivators for participating in the scheme, those serving more deprived populations highlighted financial reward. The scheme exacerbated tensions between patient and professional consultation agendas, general practitioners

  11. Hybrid scheme for color dithering

    NASA Astrophysics Data System (ADS)

    Sloan, Kenneth R., Jr.

    1990-10-01

    This paper presents a hybrid color dithering scheme suitable for rendering continuous tone color images on a CRT display with a small number (on the order of 16-256) of distinct colors. Monochrome (especially bi-level) dithering techniques are well studied. Which of these techniques extend naturally to color? We look at four classes of monochrome dithering techniques and attempt to generalize each one, first to multiple gray-level (but still monochrome) inks and then to a multiple color pallette. In the monochrome case, we discover that texture introduced by the dithering process can significantly affect the appearance of the image. We develop a scheme by which the user can control these texture effects. The primary tradeoff is between very fine grained textures which depend critically on the local gray level and relatively coarser, more obvious, textures which appear uniform across the entire image. In the color case, we have the further complication of choosing a color pallette. We deal primarily with the case where there are a small number of available colors, and where the color pallette is not optimized separately for each image.

  12. High-Order Energy Stable WENO Schemes

    NASA Technical Reports Server (NTRS)

    Yamaleev, Nail K.; Carpenter, Mark H.

    2008-01-01

    A new third-order Energy Stable Weighted Essentially NonOscillatory (ESWENO) finite difference scheme for scalar and vector linear hyperbolic equations with piecewise continuous initial conditions is developed. The new scheme is proven to be stable in the energy norm for both continuous and discontinuous solutions. In contrast to the existing high-resolution shock-capturing schemes, no assumption that the reconstruction should be total variation bounded (TVB) is explicitly required to prove stability of the new scheme. A rigorous truncation error analysis is presented showing that the accuracy of the 3rd-order ESWENO scheme is drastically improved if the tuning parameters of the weight functions satisfy certain criteria. Numerical results show that the new ESWENO scheme is stable and significantly outperforms the conventional third-order WENO finite difference scheme of Jiang and Shu in terms of accuracy, while providing essentially nonoscillatory solutions near strong discontinuities.

  13. Channel Aggregation Schemes for Cognitive Radio Networks

    NASA Astrophysics Data System (ADS)

    Lee, Jongheon; So, Jaewoo

    This paper proposed three channel aggregation schemes for cognitive radio networks, a constant channel aggregation scheme, a probability distribution-based variable channel aggregation scheme, and a residual channel-based variable channel aggregation scheme. A cognitive radio network can have a wide bandwidth if unused channels in the primary networks are aggregated. Channel aggregation schemes involve either constant channel aggregation or variable channel aggregation. In this paper, a Markov chain is used to develop an analytical model of channel aggregation schemes; and the performance of the model is evaluated in terms of the average sojourn time, the average throughput, the forced termination probability, and the blocking probability. Simulation results show that channel aggregation schemes can reduce the average sojourn time of cognitive users by increasing the channel occupation rate of unused channels in a primary network.

  14. Training of Medical Physicists: Some Existing Training Schemes.

    ERIC Educational Resources Information Center

    Lanzl, Lawrence H.

    As an address to a seminar held in Germany, a summary is made concerning the present status and future development of medical physicist preparation in the U.S.A. A total of 121 programs are discussed on the basis of degree levels. Most training schemes consist of lectures, laboratory courses, and research activities with actual experience provided…

  15. Efficient implementation of weighted ENO schemes

    NASA Technical Reports Server (NTRS)

    Jiang, Guang-Shan; Shu, Chi-Wang

    1995-01-01

    In this paper, we further analyze, test, modify and improve the high order WENO (weighted essentially non-oscillatory) finite difference schemes of Liu, Osher and Chan. It was shown by Liu et al. that WENO schemes constructed from the r-th order (in L1 norm) ENO schemes are (r+1)-th order accurate. We propose a new way of measuring the smoothness of a numerical solution, emulating the idea of minimizing the total variation of the approximation, which results in a 5-th order WENO scheme for the case r = 3, instead of the 4-th order with the original smoothness measurement by Liu et al. This 5-th order WENO scheme is as fast as the 4-th order WENO scheme of Liu et al., and both schemes are about twice as fast as the 4-th order ENO schemes on vector supercomputers and as fast on serial and parallel computers. For Euler systems of gas dynamics, we suggest computing the weights from pressure and entropy instead of the characteristic values to simplify the costly characteristic procedure. The resulting WENO schemes are about twice as fast as the WENO schemes using the characteristic decompositions to compute weights, and work well for problems which do not contain strong shocks or strong reflected waves. We also prove that, for conservation laws with smooth solutions, all WENO schemes are convergent. Many numerical tests, including the 1D steady state nozzle flow problem and 2D shock entropy wave interaction problem, are presented to demonstrate the remarkable capability of the WENO schemes, especially the WENO scheme using the new smoothness measurement, in resolving complicated shock and flow structures. We have also applied Yang's artificial compression method to the WENO schemes to sharpen contact discontinuities.

  16. Same-day identification scheme for colonies of Listeria monocytogenes.

    PubMed Central

    Lachica, R V

    1990-01-01

    A diagnostic scheme is described for the same-day identification of food-borne cells of Listeria monocytogenes that emerge in 40 h at 30 degrees C as large colonies, representatives of which are used to advantage as heavy inocula on agar plates for the rapid determination of hemolytic activity and acidification of rhamnose and xylose. Additional tests consisting of phase-contrast microscopy for cell morphology and motility, the catalase production test, and the KOH viscosity test in place of Gram staining complete the rapid identification scheme. PMID:2111113

  17. Comparison of different incremental analysis update schemes in a realistic assimilation system with Ensemble Kalman Filter

    NASA Astrophysics Data System (ADS)

    Yan, Y.; Barth, A.; Beckers, J. M.; Brankart, J. M.; Brasseur, P.; Candille, G.

    2017-07-01

    In this paper, three incremental analysis update schemes (IAU 0, IAU 50 and IAU 100) are compared in the same assimilation experiments with a realistic eddy permitting primitive equation model of the North Atlantic Ocean using the Ensemble Kalman Filter. The difference between the three IAU schemes lies on the position of the increment update window. The relevance of each IAU scheme is evaluated through analyses on both thermohaline and dynamical variables. The validation of the assimilation results is performed according to both deterministic and probabilistic metrics against different sources of observations. For deterministic validation, the ensemble mean and the ensemble spread are compared to the observations. For probabilistic validation, the continuous ranked probability score (CRPS) is used to evaluate the ensemble forecast system according to reliability and resolution. The reliability is further decomposed into bias and dispersion by the reduced centred random variable (RCRV) score. The obtained results show that 1) the IAU 50 scheme has the same performance as the IAU 100 scheme 2) the IAU 50/100 schemes outperform the IAU 0 scheme in error covariance propagation for thermohaline variables in relatively stable region, while the IAU 0 scheme outperforms the IAU 50/100 schemes in dynamical variables estimation in dynamically active region 3) in case with sufficient number of observations and good error specification, the impact of IAU schemes is negligible. The differences between the IAU 0 scheme and the IAU 50/100 schemes are mainly due to different model integration time and different instability (density inversion, large vertical velocity, etc.) induced by the increment update. The longer model integration time with the IAU 50/100 schemes, especially the free model integration, on one hand, allows for better re-establishment of the equilibrium model state, on the other hand, smooths the strong gradients in dynamically active region.

  18. Matroids and quantum-secret-sharing schemes

    SciTech Connect

    Sarvepalli, Pradeep; Raussendorf, Robert

    2010-05-15

    A secret-sharing scheme is a cryptographic protocol to distribute a secret state in an encoded form among a group of players such that only authorized subsets of the players can reconstruct the secret. Classically, efficient secret-sharing schemes have been shown to be induced by matroids. Furthermore, access structures of such schemes can be characterized by an excluded minor relation. No such relations are known for quantum secret-sharing schemes. In this paper we take the first steps toward a matroidal characterization of quantum-secret-sharing schemes. In addition to providing a new perspective on quantum-secret-sharing schemes, this characterization has important benefits. While previous work has shown how to construct quantum-secret-sharing schemes for general access structures, these schemes are not claimed to be efficient. In this context the present results prove to be useful; they enable us to construct efficient quantum-secret-sharing schemes for many general access structures. More precisely, we show that an identically self-dual matroid that is representable over a finite field induces a pure-state quantum-secret-sharing scheme with information rate 1.

  19. Study on launch scheme of space-net capturing system.

    PubMed

    Gao, Qingyu; Zhang, Qingbin; Feng, Zhiwei; Tang, Qiangang

    2017-01-01

    With the continuous progress in active debris-removal technology, scientists are increasingly concerned about the concept of space-net capturing system. The space-net capturing system is a long-range-launch flexible capture system, which has great potential to capture non-cooperative targets such as inactive satellites and upper stages. In this work, the launch scheme is studied by experiment and simulation, including two-step ejection and multi-point-traction analyses. The numerical model of the tether/net is based on finite element method and is verified by full-scale ground experiment. The results of the ground experiment and numerical simulation show that the two-step ejection and six-point traction scheme of the space-net system is superior to the traditional one-step ejection and four-point traction launch scheme.

  20. Study on launch scheme of space-net capturing system

    PubMed Central

    Zhang, Qingbin; Feng, Zhiwei; Tang, Qiangang

    2017-01-01

    With the continuous progress in active debris-removal technology, scientists are increasingly concerned about the concept of space-net capturing system. The space-net capturing system is a long-range-launch flexible capture system, which has great potential to capture non-cooperative targets such as inactive satellites and upper stages. In this work, the launch scheme is studied by experiment and simulation, including two-step ejection and multi-point-traction analyses. The numerical model of the tether/net is based on finite element method and is verified by full-scale ground experiment. The results of the ground experiment and numerical simulation show that the two-step ejection and six-point traction scheme of the space-net system is superior to the traditional one-step ejection and four-point traction launch scheme. PMID:28877187

  1. Rapid Parameterization Schemes for Aircraft Shape Optimization

    NASA Technical Reports Server (NTRS)

    Li, Wu

    2012-01-01

    A rapid shape parameterization tool called PROTEUS is developed for aircraft shape optimization. This tool can be applied directly to any aircraft geometry that has been defined in PLOT3D format, with the restriction that each aircraft component must be defined by only one data block. PROTEUS has eight types of parameterization schemes: planform, wing surface, twist, body surface, body scaling, body camber line, shifting/scaling, and linear morphing. These parametric schemes can be applied to two types of components: wing-type surfaces (e.g., wing, canard, horizontal tail, vertical tail, and pylon) and body-type surfaces (e.g., fuselage, pod, and nacelle). These schemes permit the easy setup of commonly used shape modification methods, and each customized parametric scheme can be applied to the same type of component for any configuration. This paper explains the mathematics for these parametric schemes and uses two supersonic configurations to demonstrate the application of these schemes.

  2. How can conceptual schemes change teaching?

    NASA Astrophysics Data System (ADS)

    Wickman, Per-Olof

    2012-03-01

    Lundqvist, Almqvist and Östman describe a teacher's manner of teaching and the possible consequences it may have for students' meaning making. In doing this the article examines a teacher's classroom practice by systematizing the teacher's transactions with the students in terms of certain conceptual schemes, namely the epistemological moves, educational philosophies and the selective traditions of this practice. In connection to their study one may ask how conceptual schemes could change teaching. This article examines how the relationship of the conceptual schemes produced by educational researchers to educational praxis has developed from the middle of the last century to today. The relationship is described as having been transformed in three steps: (1) teacher deficit and social engineering, where conceptual schemes are little acknowledged, (2) reflecting practitioners, where conceptual schemes are mangled through teacher practice to aid the choices of already knowledgeable teachers, and (3) the mangling of the conceptual schemes by researchers through practice with the purpose of revising theory.

  3. A privacy preserving secure and efficient authentication scheme for telecare medical information systems.

    PubMed

    Mishra, Raghavendra; Barnwal, Amit Kumar

    2015-05-01

    The Telecare medical information system (TMIS) presents effective healthcare delivery services by employing information and communication technologies. The emerging privacy and security are always a matter of great concern in TMIS. Recently, Chen at al. presented a password based authentication schemes to address the privacy and security. Later on, it is proved insecure against various active and passive attacks. To erase the drawbacks of Chen et al.'s anonymous authentication scheme, several password based authentication schemes have been proposed using public key cryptosystem. However, most of them do not present pre-smart card authentication which leads to inefficient login and password change phases. To present an authentication scheme with pre-smart card authentication, we present an improved anonymous smart card based authentication scheme for TMIS. The proposed scheme protects user anonymity and satisfies all the desirable security attributes. Moreover, the proposed scheme presents efficient login and password change phases where incorrect input can be quickly detected and a user can freely change his password without server assistance. Moreover, we demonstrate the validity of the proposed scheme by utilizing the widely-accepted BAN (Burrows, Abadi, and Needham) logic. The proposed scheme is also comparable in terms of computational overheads with relevant schemes.

  4. On the security of two remote user authentication schemes for telecare medical information systems.

    PubMed

    Kim, Kee-Won; Lee, Jae-Dong

    2014-05-01

    The telecare medical information systems (TMISs) support convenient and rapid health-care services. A secure and efficient authentication scheme for TMIS provides safeguarding patients' electronic patient records (EPRs) and helps health care workers and medical personnel to rapidly making correct clinical decisions. Recently, Kumari et al. proposed a password based user authentication scheme using smart cards for TMIS, and claimed that the proposed scheme could resist various malicious attacks. However, we point out that their scheme is still vulnerable to lost smart card and cannot provide forward secrecy. Subsequently, Das and Goswami proposed a secure and efficient uniqueness-and-anonymity-preserving remote user authentication scheme for connected health care. They simulated their scheme for the formal security verification using the widely-accepted automated validation of Internet security protocols and applications (AVISPA) tool to ensure that their scheme is secure against passive and active attacks. However, we show that their scheme is still vulnerable to smart card loss attacks and cannot provide forward secrecy property. The proposed cryptanalysis discourages any use of the two schemes under investigation in practice and reveals some subtleties and challenges in designing this type of schemes.

  5. Review and development of common nomenclature for naming and labeling schemes for probabilistic risk assessment

    SciTech Connect

    Trusty, A.D.; Mackowiak, D.P. )

    1992-08-01

    This report describes the review and development of common nomenclature for naming and labeling schemes for probabilistic risk assessments (PRAS) conducted by the Idaho National Engineering Laboratory (INEL). Based on the review, the INEL recommends using an existing basic event labeling scheme and existing naming schemes for systems, component types, and component failure modes. The review showed no adequate accident sequence labeling schemes currently exist. Therefore, the INEL developed a scheme that would meet the review requirements of not exceeding 16 characters and being highly descriptive of the accident sequence involved. As parts of the developed accident sequence labeling scheme, the INEL also developed transient and loss-of-coolant accident initiating event codes, a sequence naming scheme, and accident type codes. Applications of the accident sequence labeling scheme are presented along with tables to allow changes from other schemes to the recommended naming schemes. The review and development were conducted to provide the Nuclear Regulatory Commission with the means to coordinate and integrate their internal activities through a common nomenclature for their many data bases.

  6. A cascaded coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Kasami, T.; Lin, S.

    1985-01-01

    A cascaded coding scheme for error control was investigated. The scheme employs a combination of hard and soft decisions in decoding. Error performance is analyzed. If the inner and outer codes are chosen properly, extremely high reliability can be attained even for a high channel bit-error-rate. Some example schemes are studied which seem to be quite suitable for satellite down-link error control.

  7. A cascaded coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Shu, L.; Kasami, T.

    1985-01-01

    A cascade coding scheme for error control is investigated. The scheme employs a combination of hard and soft decisions in decoding. Error performance is analyzed. If the inner and outer codes are chosen properly, extremely high reliability can be attained even for a high channel bit-error-rate. Some example schemes are evaluated. They seem to be quite suitable for satellite down-link error control.

  8. Curvilinear bicubic spline fit interpolation scheme

    NASA Technical Reports Server (NTRS)

    Chi, C.

    1973-01-01

    Modification of the rectangular bicubic spline fit interpolation scheme so as to make it suitable for use with a polar grid pattern. In the proposed modified scheme the interpolation function is expressed in terms of the radial length and the arc length, and the shape of the patch, which is a wedge or a truncated wedge, is taken into account implicitly. Examples are presented in which the proposed interpolation scheme was used to reproduce the equations of a hemisphere.

  9. Curvilinear bicubic spline fit interpolation scheme

    NASA Technical Reports Server (NTRS)

    Chi, C.

    1973-01-01

    Modification of the rectangular bicubic spline fit interpolation scheme so as to make it suitable for use with a polar grid pattern. In the proposed modified scheme the interpolation function is expressed in terms of the radial length and the arc length, and the shape of the patch, which is a wedge or a truncated wedge, is taken into account implicitly. Examples are presented in which the proposed interpolation scheme was used to reproduce the equations of a hemisphere.

  10. Short Signature Scheme From Bilinear Pairings

    DTIC Science & Technology

    2010-11-01

    model. 3.3 Efficiency We compare our signature scheme with the BLS scheme and ZSS scheme from the implementation point of view. PO, SM , PA, Squ, Inv, MTP ...1 SM 1 SM 2 SM Signing 1 MTP , 1 SM 1 H, 1 Inv, 1 SM 1 H, 1 Squ, 1 Inv, 1 SM Verification 1 MTP , 2 PO 1 H, 1 SM , 1 PO 1 H, 1 Squ, 1 SM , 2 PA, 1 PO

  11. Frost Growth CFD Model of an Integrated Active Desiccant Rooftop Unit

    SciTech Connect

    Geoghegan, Patrick J; Petrov, Andrei Y; Vineyard, Edward Allan; Zaltash, Abdolreza; Linkous, Randall Lee

    2008-01-01

    A frost growth model is incorporated into a Computational Fluid Dynamics (CFD) simulation of a heat pump by means of a user-defined function in FLUENT, a commercial CFD code. The transient model is applied to the outdoor section of an Integrated Active Desiccant Rooftop (IADR) unit in heating mode. IADR is a hybrid vapor compression and active desiccant unit capable of handling 100% outdoor air (dedicated outdoor air system) or as a total conditioning system, handling both outdoor air and space cooling or heating loads. The predicted increase in flow resistance and loss in heat transfer capacity due to frost build-up are compared to experimental pressure drop readings and thermal imaging. The purpose of this work is to develop a CFD model that is capable of predicting frost growth, an invaluable tool in evaluating the effectiveness of defrost-on-demand cycles.

  12. A dispersion reducing convective finite difference scheme

    NASA Astrophysics Data System (ADS)

    Matus, R. J.; Hindman, R. G.

    1986-01-01

    A one-parameter family of finite difference schemes for systems of convective equations has been developed and applied to the inviscid Burgers' equation and the one-dimensional, unsteady Euler equations. The parameter, alpha, may be chosen in a way to reduce the phase error of the numerical solution compared to other commonly used second order difference schemes, and computational results are included which show the ability of the scheme, called the alpha-scheme in this paper, to calculate solutions which contain discontinuities with very little oscillation. For linear one-dimensional problems, the scheme reduces to Fromm's zero average phase error method, but the present scheme differs from Fromm's in that it is easily applied to nonlinear systems of equations such as the Euler equations describing inviscid fluid flow. A modified MacCormack scheme and Warming and Beam's predictor-corrector upwind scheme are also members of the family of schemes which can be retrieved for particular choices of the parameter, alpha.

  13. Nonlinearly stable compact schemes for shock calculations

    NASA Technical Reports Server (NTRS)

    Cockburn, Bernardo; Shu, Chi-Wang

    1992-01-01

    The applications of high-order, compact finite difference methods in shock calculations are discussed. The main concern is to define a local mean which will serve as a reference for introducing a local nonlinear limiting to control spurious numerical oscillations while maintaining the formal accuracy of the scheme. For scalar conservation laws, the resulting schemes can be proven total-variation stable in one space dimension and maximum-norm stable in multiple space dimensions. Numerical examples are shown to verify accuracy and stability of such schemes for problems containing shocks. These ideas can also be applied to other implicit schemes such as the continuous Galerkin finite element methods.

  14. ID-based encryption scheme with revocation

    NASA Astrophysics Data System (ADS)

    Othman, Hafizul Azrie; Ismail, Eddie Shahril

    2017-04-01

    In 2015, Meshram proposed an efficient ID-based cryptographic encryption based on the difficulty of solving discrete logarithm and integer-factoring problems. The scheme was pairing free and claimed to be secure against adaptive chosen plaintext attacks (CPA). Later, Tan et al. proved that the scheme was insecure by presenting a method to recover the secret master key and to obtain prime factorization of modulo n. In this paper, we propose a new pairing-free ID-based encryption scheme with revocation based on Meshram's ID-based encryption scheme, which is also secure against Tan et al.'s attacks.

  15. On Tenth Order Central Spatial Schemes

    SciTech Connect

    Sjogreen, B; Yee, H C

    2007-05-14

    This paper explores the performance of the tenth-order central spatial scheme and derives the accompanying energy-norm stable summation-by-parts (SBP) boundary operators. The objective is to employ the resulting tenth-order spatial differencing with the stable SBP boundary operators as a base scheme in the framework of adaptive numerical dissipation control in high order multistep filter schemes of Yee et al. (1999), Yee and Sj{umlt o}green (2002, 2005, 2006, 2007), and Sj{umlt o}green and Yee (2004). These schemes were designed for multiscale turbulence flows including strong shock waves and combustion.

  16. On central-difference and upwind schemes

    NASA Technical Reports Server (NTRS)

    Swanson, R. C.; Turkel, Eli

    1990-01-01

    A class of numerical dissipation models for central-difference schemes constructed with second- and fourth-difference terms is considered. The notion of matrix dissipation associated with upwind schemes is used to establish improved shock capturing capability for these models. In addition, conditions are given that guarantee that such dissipation models produce a Total Variation Diminishing (TVD) scheme. Appropriate switches for this type of model to ensure satisfaction of the TVD property are presented. Significant improvements in the accuracy of a central-difference scheme are demonstrated by computing both inviscid and viscous transonic airfoil flows.

  17. Students' Whole Number Multiplicative Concepts: A Critical Constructive Resource for Fraction Composition Schemes

    ERIC Educational Resources Information Center

    Hackenberg, Amy J.; Tillema, Erik S.

    2009-01-01

    This article reports on the activity of two pairs of sixth grade students who participated in an 8-month teaching experiment that investigated the students' construction of fraction composition schemes. A fraction composition scheme consists of the operations and concepts used to determine, for example, the size of 1/3 of 1/5 of a whole in…

  18. Incorporating Partner Practice and Writing and Self-Regulation into the Theme Scheme Program.

    ERIC Educational Resources Information Center

    Williams, Joanna P.

    2003-01-01

    This article discusses activities developed for the "Theme Scheme," an instructional program for elementary and middle school children at risk for failure. "Theme Scheme" is a listening and reading comprehension program that uses peer-assisted learning strategies and writing exercises to teach students to understand text at an…

  19. Syllabic Schemes and Knowledge of the Alphabet in Reading Acquisition: "Onset" or "Nucleus" Variation

    ERIC Educational Resources Information Center

    Díaz-Cárdenas, A. F.; Díaz-Furlong, H. A.; Díaz-Furlong, A.; Sankey-García, M. R.

    2016-01-01

    Although there is a growing consensus that, in reading acquisition, it is essential to provide children with learning activities that promote the development of reading cognitive schemes, particularly intra-syllabic related patterns, there is no agreement on which kind of syllabic schemes should be worked out in the first place. The main aim of…

  20. Nutrient profiling schemes: overview and comparative analysis.

    PubMed

    Garsetti, Marcella; de Vries, Jan; Smith, Maurice; Amosse, Amélie; Rolf-Pedersen, Nathalie

    2007-12-01

    Nutrient profiling is a discipline aimed at classifying foods based on their nutritional composition. So far, several profiling schemes have been proposed for varied purposes world-wide. Primary aim to inventory the main profiling schemes that have been developed so far (both applied and not) and to summarise their main aspects. Secondary aim to critically review a selection of them, to test their "performance" and to evaluate their strengths and weaknesses. Scientific and popular search engines were used for identifying profiling schemes. Schemes were described concisely by providing details on four main "Building Blocks" or factors: (1) Food category declination: category-wise or "across the board"; (2) Reference amount: 100 g, 100 kcal; serving; (3) Cut-off use: thresholds or scores; (4) Nutrients Selection: balance between positive and negative nutrients and number of them. The "performance" analysis was done by testing how the selected schemes classify a sample of food. Profiling schemes display considerable variation based on the underlying approach, format and content. Moreover, the rationale of the schemes largely varies and seems to be inspired by either nutrient recommendations or regulations figures. When tested for "performance", the five selected schemes classify in the same way foods having either a very "positive" or a very "negative" nutrient profile, whereas they give inconsistent results for food products with intermediate characteristics. Strengths and weaknesses analysis shows the difficulty of finding schemes combining qualities such as simplicity, scientific relevance, ability to cope with changes in nutrient recommendations. Current proposed profiling schemes exhibit a wide range of differences both in terms of approaches and "performance". Nutrition scientists have now the challenge to develop the "ideal scheme" that, in our view, will have to be strict enough to ensure consumer protection but also flexible enough to encourage food industry

  1. Modified Mean-Pyramid Coding Scheme

    NASA Technical Reports Server (NTRS)

    Cheung, Kar-Ming; Romer, Richard

    1996-01-01

    Modified mean-pyramid coding scheme requires transmission of slightly fewer data. Data-expansion factor reduced from 1/3 to 1/12. Schemes for progressive transmission of image data transmitted in sequence of frames in such way coarse version of image reconstructed after receipt of first frame and increasingly refined version of image reconstructed after receipt of each subsequent frame.

  2. Practical formulation of a positively conservative scheme

    NASA Astrophysics Data System (ADS)

    Obayashi, Shigeru; Wada, Yasuhiro

    1994-05-01

    Approximate Riemann solvers have been highly successful for computing the Euler/Navier-Stokes equations, but linearized Riemann solvers are known to fail occasionally by predicting non-physical states with negative density or internal energy. Positively conservative schemes, in contrast, guarantee physical solutions from realistic input. The Harten-Lax-van Leer-Einfeldt (HLLE) scheme is a typical example of a positively conservative scheme. However, the HLLE scheme is highly dissipative at contact discontinuities and shear layers and thus it is not applicable to practicle simulations. An existing modification to the HLLE scheme, known as HLLEM, enhances the resolution to that of the Roe scheme. However, this modification violates the positivity of density and internal energy. Precise derivation of the modification yields a quatratic inequality and thus requires a case-by-case treatment. This Note describes a new, modified HLLE scheme that satisfies the positively conservative condition approximately. Sample computationa are included to demonstrate the resolution and the robustness of the scheme.

  3. Eno-Osher schemes for Euler equations

    NASA Technical Reports Server (NTRS)

    Vandervegt, Jacobus J.

    1992-01-01

    The combination of the Osher approximate Riemann solver for the Euler equations and various ENO schemes is discussed for one-dimensional flow. The three basic approaches, viz. the ENO scheme using primitive variable reconstruction, either with Cauchy-Kowalewski procedure for time integration or the TVD Runge-Kutta scheme, and the flux-ENO method are tested on different shock tube cases. The shock tube cases were chosen to present a serious challenge to the ENO schemes in order to test their ability to capture flow discontinuities, such as shocks. Also the effect of the ordering of the eigen values, viz. natural or reversed ordering, in the Osher scheme is investigated. The ENO schemes are tested up to fifth order accuracy in space and time. The ENO-Osher scheme using the Cauchy-Kowalewski procedure for time integration is found to be the most accurate and robust compared with the other methods and is also computationally efficient. The tests showed that the ENO schemes perform reasonably well, but have problems in cases where two discontinuities are close together. In that case there are not enough points in the smooth part of the flow to create a non-oscillatory interpolation.

  4. Finite volume renormalization scheme for fermionic operators

    SciTech Connect

    Monahan, Christopher; Orginos, Kostas

    2013-11-01

    We propose a new finite volume renormalization scheme. Our scheme is based on the Gradient Flow applied to both fermion and gauge fields and, much like the Schr\\"odinger functional method, allows for a nonperturbative determination of the scale dependence of operators using a step-scaling approach. We give some preliminary results for the pseudo-scalar density in the quenched approximation.

  5. Modeling Students' Mathematics Using Steffe's Fraction Schemes

    ERIC Educational Resources Information Center

    Norton, Anderson H.; McCloskey, Andrea V.

    2008-01-01

    Each year, more teachers learn about the successful intervention program known as Math Recovery (USMRC 2008; Wright 2003). The program uses Steffe's whole-number schemes to model, understand, and support children's development of whole-number reasoning. Readers are probably less familiar with Steffe's fraction schemes, which have proven similarly…

  6. Phase calibration scheme for a ``T'' array

    NASA Astrophysics Data System (ADS)

    Ramesh, R.; Subramanian, K. R.; Sastry, Ch. V.

    1999-10-01

    A calibration scheme based on closure and redundancy techniques is described for correcting the phase errors in the complex visibilities observed with a T-shaped radio interferometer array. Practical details of the scheme are illustrated with reference to the Gauribidanur radioheliograph (GRH).

  7. A Resilient Quantum Secret Sharing Scheme

    NASA Astrophysics Data System (ADS)

    Maitra, Arpita; Paul, Goutam

    2015-02-01

    A resilient secret sharing scheme is supposed to generate the secret correctly even after some shares are damaged. In this paper, we show how quantum error correcting codes can be exploited to design a resilient quantum secret sharing scheme, where a quantum state is shared among more than one parties.

  8. Localization scheme for relativistic spinors

    NASA Astrophysics Data System (ADS)

    Ciupka, J.; Hanrath, M.; Dolg, M.

    2011-12-01

    A new method to determine localized complex-valued one-electron functions in the occupied space is presented. The approach allows the calculation of localized orbitals regardless of their structure and of the entries in the spinor coefficient matrix, i.e., one-, two-, and four-component Kramers-restricted or unrestricted one-electron functions with real or complex expansion coefficients. The method is applicable to localization schemes that maximize (or minimize) a functional of the occupied spinors and that use a localization operator for which a matrix representation is available. The approach relies on the approximate joint diagonalization (AJD) of several Hermitian (symmetric) matrices which is utilized in electronic signal processing. The use of AJD in this approach has the advantage that it allows a reformulation of the localization criterion on an iterative 2 × 2 pair rotating basis in an analytical closed form which has not yet been described in the literature for multi-component (complex-valued) spinors. For the one-component case, the approach delivers the same Foster-Boys or Pipek-Mezey localized orbitals that one obtains from standard quantum chemical software, whereas in the multi-component case complex-valued spinors satisfying the selected localization criterion are obtained. These localized spinors allow the formulation of local correlation methods in a multi-component relativistic framework, which was not yet available. As an example, several heavy and super-heavy element systems are calculated using a Kramers-restricted self-consistent field and relativistic two-component pseudopotentials in order to investigate the effect of spin-orbit coupling on localization.

  9. Efficient DSMC collision-partner selection schemes.

    SciTech Connect

    Gallis, Michail A.; Torczynski, John Robert

    2010-05-01

    The effect of collision-partner selection schemes on the accuracy and the efficiency of the Direct Simulation Monte Carlo (DSMC) method of Bird is investigated. Several schemes to reduce the total discretization error as a function of the mean collision separation and the mean collision time are examined. These include the historically first sub-cell scheme, the more recent nearest-neighbor scheme, and various near-neighbor schemes, which are evaluated for their effect on the thermal conductivity for Fourier flow. Their convergence characteristics as a function of spatial and temporal discretization and the number of simulators per cell are compared to the convergence characteristics of the sophisticated and standard DSMC algorithms. Improved performance is obtained if the population from which possible collision partners are selected is an appropriate fraction of the population of the cell.

  10. The basic function scheme of polynomial type

    SciTech Connect

    WU, Wang-yi; Lin, Guang

    2009-12-01

    A new numerical method---Basic Function Method is proposed. This method can directly discrete differential operator on unstructured grids. By using the expansion of basic function to approach the exact function, the central and upwind schemes of derivative are constructed. By using the second-order polynomial as basic function and applying the technique of flux splitting method and the combination of central and upwind schemes to suppress the non-physical fluctuation near the shock wave, the second-order basic function scheme of polynomial type for solving inviscid compressible flow numerically is constructed in this paper. Several numerical results of many typical examples for two dimensional inviscid compressible transonic and supersonic steady flow illustrate that it is a new scheme with high accuracy and high resolution for shock wave. Especially, combining with the adaptive remeshing technique, the satisfactory results can be obtained by these schemes.

  11. Efficient DSMC collision-partner selection schemes.

    SciTech Connect

    Gallis, Michail A.; Torczynski, John Robert

    2010-07-01

    The effect of collision-partner selection schemes on the accuracy and the efficiency of the Direct Simulation Monte Carlo (DSMC) method of Bird is investigated. Several schemes to reduce the total discretization error as a function of the mean collision separation and the mean collision time are examined. These include the historically first sub-cell scheme, the more recent nearest-neighbor scheme, and various near-neighbor schemes, which are evaluated for their effect on the thermal conductivity for Fourier flow. Their convergence characteristics as a function of spatial and temporal discretization and the number of simulators per cell are compared to the convergence characteristics of the sophisticated and standard DSMC algorithms. Improved performance is obtained if the population from which possible collision partners are selected is an appropriate fraction of the population of the cell.

  12. A Novel Quantum Proxy Blind Signature Scheme

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Xie, Shu-Cui; Zhang, Jian-Zhong

    2017-05-01

    A novel quantum proxy blind signature scheme is proposed. In this scheme, a special type of non-maximally entangled three-qubit state is introduced as a quantum channel, which can realize perfect teleportation. The message sender U blinds his message by means of preparing two groups of non-orthogonal single-photon states. According to the original signer Charlie's delegation message, the proxy signer Alice generates a corresponding signature. The arbitrator Trent can help the receiver Bob verify the signature, and also prevent Bob from doing any damage. The above-mentioned advantages make this scheme different from some existing schemes. It is showed that our scheme has the properties of undeniability, unforgeability, blindness, untraceability. Moreover, it is free from intercept-resend attack.

  13. A Novel Quantum Proxy Blind Signature Scheme

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Xie, Shu-Cui; Zhang, Jian-Zhong

    2017-02-01

    A novel quantum proxy blind signature scheme is proposed. In this scheme, a special type of non-maximally entangled three-qubit state is introduced as a quantum channel, which can realize perfect teleportation. The message sender U blinds his message by means of preparing two groups of non-orthogonal single-photon states. According to the original signer Charlie's delegation message, the proxy signer Alice generates a corresponding signature. The arbitrator Trent can help the receiver Bob verify the signature, and also prevent Bob from doing any damage. The above-mentioned advantages make this scheme different from some existing schemes. It is showed that our scheme has the properties of undeniability, unforgeability, blindness, untraceability. Moreover, it is free from intercept-resend attack.

  14. A novel key management scheme using biometrics

    NASA Astrophysics Data System (ADS)

    Sui, Yan; Yang, Kai; Du, Yingzi; Orr, Scott; Zou, Xukai

    2010-04-01

    Key management is one of the most important issues in cryptographic systems. Several important challenges in such a context are represented by secure and efficient key generation, key distribution, as well as key revocation. Addressing such challenges requires a comprehensive solution which is robust, secure and efficient. Compared to traditional key management schemes, key management using biometrics requires the presence of the user, which can reduce fraud and protect the key better. In this paper, we propose a novel key management scheme using iris based biometrics. Our newly proposed scheme outperforms traditional key management schemes as well as some existing key-binding biometric schemes in terms of security, diversity and/or efficiency.

  15. Towards a genuinely multi-dimensional upwind scheme

    NASA Technical Reports Server (NTRS)

    Powell, Kenneth G.; Vanleer, Bram; Roe, Philip L.

    1990-01-01

    Methods of incorporating multi-dimensional ideas into algorithms for the solution of Euler equations are presented. Three schemes are developed and tested: a scheme based on a downwind distribution, a scheme based on a rotated Riemann solver and a scheme based on a generalized Riemann solver. The schemes show an improvement over first-order, grid-aligned upwind schemes, but the higher-order performance is less impressive. An outlook for the future of multi-dimensional upwind schemes is given.

  16. An Efficient and Practical Smart Card Based Anonymity Preserving User Authentication Scheme for TMIS using Elliptic Curve Cryptography.

    PubMed

    Amin, Ruhul; Islam, S K Hafizul; Biswas, G P; Khan, Muhammad Khurram; Kumar, Neeraj

    2015-11-01

    In the last few years, numerous remote user authentication and session key agreement schemes have been put forwarded for Telecare Medical Information System, where the patient and medical server exchange medical information using Internet. We have found that most of the schemes are not usable for practical applications due to known security weaknesses. It is also worth to note that unrestricted number of patients login to the single medical server across the globe. Therefore, the computation and maintenance overhead would be high and the server may fail to provide services. In this article, we have designed a medical system architecture and a standard mutual authentication scheme for single medical server, where the patient can securely exchange medical data with the doctor(s) via trusted central medical server over any insecure network. We then explored the security of the scheme with its resilience to attacks. Moreover, we formally validated the proposed scheme through the simulation using Automated Validation of Internet Security Schemes and Applications software whose outcomes confirm that the scheme is protected against active and passive attacks. The performance comparison demonstrated that the proposed scheme has lower communication cost than the existing schemes in literature. In addition, the computation cost of the proposed scheme is nearly equal to the exiting schemes. The proposed scheme not only efficient in terms of different security attacks, but it also provides an efficient login, mutual authentication, session key agreement and verification and password update phases along with password recovery.

  17. A secure and robust password-based remote user authentication scheme using smart cards for the integrated EPR information system.

    PubMed

    Das, Ashok Kumar

    2015-03-01

    An integrated EPR (Electronic Patient Record) information system of all the patients provides the medical institutions and the academia with most of the patients' information in details for them to make corrective decisions and clinical decisions in order to maintain and analyze patients' health. In such system, the illegal access must be restricted and the information from theft during transmission over the insecure Internet must be prevented. Lee et al. proposed an efficient password-based remote user authentication scheme using smart card for the integrated EPR information system. Their scheme is very efficient due to usage of one-way hash function and bitwise exclusive-or (XOR) operations. However, in this paper, we show that though their scheme is very efficient, their scheme has three security weaknesses such as (1) it has design flaws in password change phase, (2) it fails to protect privileged insider attack and (3) it lacks the formal security verification. We also find that another recently proposed Wen's scheme has the same security drawbacks as in Lee at al.'s scheme. In order to remedy these security weaknesses found in Lee et al.'s scheme and Wen's scheme, we propose a secure and efficient password-based remote user authentication scheme using smart cards for the integrated EPR information system. We show that our scheme is also efficient as compared to Lee et al.'s scheme and Wen's scheme as our scheme only uses one-way hash function and bitwise exclusive-or (XOR) operations. Through the security analysis, we show that our scheme is secure against possible known attacks. Furthermore, we simulate our scheme for the formal security verification using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool and show that our scheme is secure against passive and active attacks.

  18. Towards an "All Speed" Unstructured Upwind Scheme

    NASA Technical Reports Server (NTRS)

    Loh, Ching Y.; Jorgenson, Philip C.E.

    2009-01-01

    In the authors previous studies [1], a time-accurate, upwind finite volume method (ETAU scheme) for computing compressible flows on unstructured grids was proposed. The scheme is second order accurate in space and time and yields high resolution in the presence of discontinuities. The scheme features a multidimensional limiter and multidimensional numerical dissipation. These help to stabilize the numerical process and to overcome the annoying pathological behaviors of upwind schemes. In the present paper, it will be further shown that such multidimensional treatments also lead to a nearly all-speed or Mach number insensitive upwind scheme. For flows at very high Mach number, e.g., 10, local numerical instabilities or the pathological behaviors are suppressed, while for flows at very low Mach number, e.g., 0.02, computation can be directly carried out without invoking preconditioning. For flows in different Mach number regimes, i.e., low, medium, and high Mach numbers, one only needs to adjust one or two parameters in the scheme. Several examples with low and high Mach numbers are demonstrated in this paper. Thus, the ETAU scheme is applicable to a broad spectrum of flow regimes ranging from high supersonic to low subsonic, appropriate for both CFD (computational fluid dynamics) and CAA (computational aeroacoustics).

  19. Ponzi scheme diffusion in complex networks

    NASA Astrophysics Data System (ADS)

    Zhu, Anding; Fu, Peihua; Zhang, Qinghe; Chen, Zhenyue

    2017-08-01

    Ponzi schemes taking the form of Internet-based financial schemes have been negatively affecting China's economy for the last two years. Because there is currently a lack of modeling research on Ponzi scheme diffusion within social networks yet, we develop a potential-investor-divestor (PID) model to investigate the diffusion dynamics of Ponzi scheme in both homogeneous and inhomogeneous networks. Our simulation study of artificial and real Facebook social networks shows that the structure of investor networks does indeed affect the characteristics of dynamics. Both the average degree of distribution and the power-law degree of distribution will reduce the spreading critical threshold and will speed up the rate of diffusion. A high speed of diffusion is the key to alleviating the interest burden and improving the financial outcomes for the Ponzi scheme operator. The zero-crossing point of fund flux function we introduce proves to be a feasible index for reflecting the fast-worsening situation of fiscal instability and predicting the forthcoming collapse. The faster the scheme diffuses, the higher a peak it will reach and the sooner it will collapse. We should keep a vigilant eye on the harm of Ponzi scheme diffusion through modern social networks.

  20. Symmetric weak ternary quantum homomorphic encryption schemes

    NASA Astrophysics Data System (ADS)

    Wang, Yuqi; She, Kun; Luo, Qingbin; Yang, Fan; Zhao, Chao

    2016-03-01

    Based on a ternary quantum logic circuit, four symmetric weak ternary quantum homomorphic encryption (QHE) schemes were proposed. First, for a one-qutrit rotation gate, a QHE scheme was constructed. Second, in view of the synthesis of a general 3 × 3 unitary transformation, another one-qutrit QHE scheme was proposed. Third, according to the one-qutrit scheme, the two-qutrit QHE scheme about generalized controlled X (GCX(m,n)) gate was constructed and further generalized to the n-qutrit unitary matrix case. Finally, the security of these schemes was analyzed in two respects. It can be concluded that the attacker can correctly guess the encryption key with a maximum probability pk = 1/33n, thus it can better protect the privacy of users’ data. Moreover, these schemes can be well integrated into the future quantum remote server architecture, and thus the computational security of the users’ private quantum information can be well protected in a distributed computing environment.

  1. A Real Quantum Designated Verifier Signature Scheme

    NASA Astrophysics Data System (ADS)

    Shi, Wei-Min; Zhou, Yi-Hua; Yang, Yu-Guang

    2015-09-01

    The effectiveness of most quantum signature schemes reported in the literature can be verified by a designated person, however, those quantum signature schemes aren't the real traditional designated verifier signature schemes, because the designated person hasn't the capability to efficiently simulate a signature which is indistinguishable from a signer, which cannot satisfy the requirements in some special environments such as E-voting, call for tenders and software licensing. For solving this problem, a real quantum designated verifier signature scheme is proposed in this paper. According to the property of unitary transformation and quantum one-way function, only a verifier designated by a signer can verify the "validity of a signature" and the designated verifier cannot prove to a third party that the signature was produced by the signer or by himself through a transcript simulation algorithm. Moreover, the quantum key distribution and quantum encryption algorithm guarantee the unconditional security of this scheme. Analysis results show that this new scheme satisfies the main security requirements of designated verifier signature scheme and the major attack strategies.

  2. Novel neural networks-based fault tolerant control scheme with fault alarm.

    PubMed

    Shen, Qikun; Jiang, Bin; Shi, Peng; Lim, Cheng-Chew

    2014-11-01

    In this paper, the problem of adaptive active fault-tolerant control for a class of nonlinear systems with unknown actuator fault is investigated. The actuator fault is assumed to have no traditional affine appearance of the system state variables and control input. The useful property of the basis function of the radial basis function neural network (NN), which will be used in the design of the fault tolerant controller, is explored. Based on the analysis of the design of normal and passive fault tolerant controllers, by using the implicit function theorem, a novel NN-based active fault-tolerant control scheme with fault alarm is proposed. Comparing with results in the literature, the fault-tolerant control scheme can minimize the time delay between fault occurrence and accommodation that is called the time delay due to fault diagnosis, and reduce the adverse effect on system performance. In addition, the FTC scheme has the advantages of a passive fault-tolerant control scheme as well as the traditional active fault-tolerant control scheme's properties. Furthermore, the fault-tolerant control scheme requires no additional fault detection and isolation model which is necessary in the traditional active fault-tolerant control scheme. Finally, simulation results are presented to demonstrate the efficiency of the developed techniques.

  3. Complex Modelling Scheme Of An Additive Manufacturing Centre

    NASA Astrophysics Data System (ADS)

    Popescu, Liliana Georgeta

    2015-09-01

    This paper presents a modelling scheme sustaining the development of an additive manufacturing research centre model and its processes. This modelling is performed using IDEF0, the resulting model process representing the basic processes required in developing such a centre in any university. While the activities presented in this study are those recommended in general, changes may occur in specific existing situations in a research centre.

  4. Deitmar schemes, graphs and zeta functions

    NASA Astrophysics Data System (ADS)

    Mérida-Angulo, Manuel; Thas, Koen

    2017-07-01

    In Thas (2014) it was explained how one can naturally associate a Deitmar scheme (which is a scheme defined over the field with one element, F1) to a so-called ;loose graph; (which is a generalization of a graph). Several properties of the Deitmar scheme can be proven easily from the combinatorics of the (loose) graph, and known realizations of objects over F1 such as combinatorial F1-projective and F1-affine spaces exactly depict the loose graph which corresponds to the associated Deitmar scheme. In this paper, we first modify the construction of loc. cit., and show that Deitmar schemes which are defined by finite trees (with possible end points) are ;defined over F1; in Kurokawa's sense; we then derive a precise formula for the Kurokawa zeta function for such schemes (and so also for the counting polynomial of all associated Fq-schemes). As a corollary, we find a zeta function for all such trees which contains information such as the number of inner points and the spectrum of degrees, and which is thus very different than Ihara's zeta function (which is trivial in this case). Using a process called ;surgery,; we show that one can determine the zeta function of a general loose graph and its associated {Deitmar, Grothendieck}-schemes in a number of steps, eventually reducing the calculation essentially to trees. We study a number of classes of examples of loose graphs, and introduce the Grothendieck ring ofF1-schemes along the way in order to perform the calculations. Finally, we include a computer program for performing more tedious calculations, and compare the new zeta function to Ihara's zeta function for graphs in a number of examples.

  5. A Spatial Domain Quantum Watermarking Scheme

    NASA Astrophysics Data System (ADS)

    Wei, Zhan-Hong; Chen, Xiu-Bo; Xu, Shu-Jiang; Niu, Xin-Xin; Yang, Yi-Xian

    2016-07-01

    This paper presents a spatial domain quantum watermarking scheme. For a quantum watermarking scheme, a feasible quantum circuit is a key to achieve it. This paper gives a feasible quantum circuit for the presented scheme. In order to give the quantum circuit, a new quantum multi-control rotation gate, which can be achieved with quantum basic gates, is designed. With this quantum circuit, our scheme can arbitrarily control the embedding position of watermark images on carrier images with the aid of auxiliary qubits. Besides reversely acting the given quantum circuit, the paper gives another watermark extracting algorithm based on quantum measurements. Moreover, this paper also gives a new quantum image scrambling method and its quantum circuit. Differ from other quantum watermarking schemes, all given quantum circuits can be implemented with basic quantum gates. Moreover, the scheme is a spatial domain watermarking scheme, and is not based on any transform algorithm on quantum images. Meanwhile, it can make sure the watermark be secure even though the watermark has been found. With the given quantum circuit, this paper implements simulation experiments for the presented scheme. The experimental result shows that the scheme does well in the visual quality and the embedding capacity. Supported by the National Natural Science Foundation of China under Grant Nos. 61272514, 61170272, 61373131, 61121061, 61411146001, the program for New Century Excellent Talents under Grant No. NCET-13-0681, the National Development Foundation for Cryptological Research (Grant No. MMJJ201401012) and the Fok Ying Tung Education Foundation under Grant No. 131067, and the Shandong Provincial Natural Science Foundation of China under Grant No. ZR2013FM025

  6. A physical classification scheme for blazars

    NASA Astrophysics Data System (ADS)

    Landt, Hermine; Padovani, Paolo; Perlman, Eric S.; Giommi, Paolo

    2004-06-01

    Blazars are currently separated into BL Lacertae objects (BL Lacs) and flat spectrum radio quasars based on the strength of their emission lines. This is performed rather arbitrarily by defining a diagonal line in the Ca H&K break value-equivalent width plane, following Marchã et al. We readdress this problem and put the classification scheme for blazars on firm physical grounds. We study ~100 blazars and radio galaxies from the Deep X-ray Radio Blazar Survey (DXRBS) and 2-Jy radio survey and find a significant bimodality for the narrow emission line [OIII]λ5007. This suggests the presence of two physically distinct classes of radio-loud active galactic nuclei (AGN). We show that all radio-loud AGN, blazars and radio galaxies, can be effectively separated into weak- and strong-lined sources using the [OIII]λ5007-[OII]λ3727 equivalent width plane. This plane allows one to disentangle orientation effects from intrinsic variations in radio-loud AGN. Based on DXRBS, the strongly beamed sources of the new class of weak-lined radio-loud AGN are made up of BL Lacs at the ~75 per cent level, whereas those of the strong-lined radio-loud AGN include mostly (~97 per cent) quasars.

  7. Testing hydrodynamics schemes in galaxy disc simulations

    NASA Astrophysics Data System (ADS)

    Few, C. G.; Dobbs, C.; Pettitt, A.; Konstandin, L.

    2016-08-01

    We examine how three fundamentally different numerical hydrodynamics codes follow the evolution of an isothermal galactic disc with an external spiral potential. We compare an adaptive mesh refinement code (RAMSES), a smoothed particle hydrodynamics code (SPHNG), and a volume-discretized mesh-less code (GIZMO). Using standard refinement criteria, we find that RAMSES produces a disc that is less vertically concentrated and does not reach such high densities as the SPHNG or GIZMO runs. The gas surface density in the spiral arms increases at a lower rate for the RAMSES simulations compared to the other codes. There is also a greater degree of substructure in the SPHNG and GIZMO runs and secondary spiral arms are more pronounced. By resolving the Jeans length with a greater number of grid cells, we achieve more similar results to the Lagrangian codes used in this study. Other alterations to the refinement scheme (adding extra levels of refinement and refining based on local density gradients) are less successful in reducing the disparity between RAMSES and SPHNG/GIZMO. Although more similar, SPHNG displays different density distributions and vertical mass profiles to all modes of GIZMO (including the smoothed particle hydrodynamics version). This suggests differences also arise which are not intrinsic to the particular method but rather due to its implementation. The discrepancies between codes (in particular, the densities reached in the spiral arms) could potentially result in differences in the locations and time-scales for gravitational collapse, and therefore impact star formation activity in more complex galaxy disc simulations.

  8. A classification scheme for chimera states

    NASA Astrophysics Data System (ADS)

    Kemeth, Felix P.; Haugland, Sindre W.; Schmidt, Lennart; Kevrekidis, Ioannis G.; Krischer, Katharina

    2016-09-01

    We present a universal characterization scheme for chimera states applicable to both numerical and experimental data sets. The scheme is based on two correlation measures that enable a meaningful definition of chimera states as well as their classification into three categories: stationary, turbulent, and breathing. In addition, these categories can be further subdivided according to the time-stationarity of these two measures. We demonstrate that this approach is both consistent with previously recognized chimera states and enables us to classify states as chimeras which have not been categorized as such before. Furthermore, the scheme allows for a qualitative and quantitative comparison of experimental chimeras with chimeras obtained through numerical simulations.

  9. The Overseas Doctors Training Scheme: failing expectations.

    PubMed Central

    Richards, T.

    1994-01-01

    The Overseas Doctors Training Scheme needs appraisal. Set up 10 years ago to improve the quality of postgraduate training that overseas (non-European) doctors receive in Britain, the scheme has been popular, but it is questionable how far it has achieved its aims. If Britain is to continue to employ large numbers of overseas doctors in training grades, both through the scheme and through independent arrangements, the apparent mismatch between their expectations and the reality of what Britain offers must be tackled. Images p1629-a PMID:7993422

  10. Galilean invariant resummation schemes of cosmological perturbations

    NASA Astrophysics Data System (ADS)

    Peloso, Marco; Pietroni, Massimo

    2017-01-01

    Many of the methods proposed so far to go beyond Standard Perturbation Theory break invariance under time-dependent boosts (denoted here as extended Galilean Invariance, or GI). This gives rise to spurious large scale effects which spoil the small scale predictions of these approximation schemes. By using consistency relations we derive fully non-perturbative constraints that GI imposes on correlation functions. We then introduce a method to quantify the amount of GI breaking of a given scheme, and to correct it by properly tailored counterterms. Finally, we formulate resummation schemes which are manifestly GI, discuss their general features, and implement them in the so called Time-Flow, or TRG, equations.

  11. A classification scheme for chimera states.

    PubMed

    Kemeth, Felix P; Haugland, Sindre W; Schmidt, Lennart; Kevrekidis, Ioannis G; Krischer, Katharina

    2016-09-01

    We present a universal characterization scheme for chimera states applicable to both numerical and experimental data sets. The scheme is based on two correlation measures that enable a meaningful definition of chimera states as well as their classification into three categories: stationary, turbulent, and breathing. In addition, these categories can be further subdivided according to the time-stationarity of these two measures. We demonstrate that this approach is both consistent with previously recognized chimera states and enables us to classify states as chimeras which have not been categorized as such before. Furthermore, the scheme allows for a qualitative and quantitative comparison of experimental chimeras with chimeras obtained through numerical simulations.

  12. Finite-volume scheme for anisotropic diffusion

    SciTech Connect

    Es, Bram van; Koren, Barry; Blank, Hugo J. de

    2016-02-01

    In this paper, we apply a special finite-volume scheme, limited to smooth temperature distributions and Cartesian grids, to test the importance of connectivity of the finite volumes. The area of application is nuclear fusion plasma with field line aligned temperature gradients and extreme anisotropy. We apply the scheme to the anisotropic heat-conduction equation, and compare its results with those of existing finite-volume schemes for anisotropic diffusion. Also, we introduce a general model adaptation of the steady diffusion equation for extremely anisotropic diffusion problems with closed field lines.

  13. Chaotic cryptographic scheme and its randomness evaluation

    NASA Astrophysics Data System (ADS)

    Stoyanov, B. P.

    2012-10-01

    We propose a new cryptographic scheme based on the Lorenz chaos attractor and 32 bit bent Boolean function. We evaluated the keystream generated by the scheme with batteries of the NIST statistical tests. We also applied a number of statistical analysis techniques, such as calculating histograms, correlations between two adjacent pixels, information entropy, and differential resistance, all refer to images encrypted by the proposed system. The results of the analysis show that the new cryptographic scheme ensures a secure way for sending digital data with potential applications in real-time image encryption.

  14. The GEMPAK Barnes objective analysis scheme

    NASA Technical Reports Server (NTRS)

    Koch, S. E.; Desjardins, M.; Kocin, P. J.

    1981-01-01

    GEMPAK, an interactive computer software system developed for the purpose of assimilating, analyzing, and displaying various conventional and satellite meteorological data types is discussed. The objective map analysis scheme possesses certain characteristics that allowed it to be adapted to meet the analysis needs GEMPAK. Those characteristics and the specific adaptation of the scheme to GEMPAK are described. A step-by-step guide for using the GEMPAK Barnes scheme on an interactive computer (in real time) to analyze various types of meteorological datasets is also presented.

  15. A diagonally inverted LU implicit multigrid scheme

    NASA Technical Reports Server (NTRS)

    Yokota, Jeffrey W.; Caughey, David A.; Chima, Rodrick V.

    1988-01-01

    A new Diagonally Inverted LU Implicit scheme is developed within the framework of the multigrid method for the 3-D unsteady Euler equations. The matrix systems that are to be inverted in the LU scheme are treated by local diagonalizing transformations that decouple them into systems of scalar equations. Unlike the Diagonalized ADI method, the time accuracy of the LU scheme is not reduced since the diagonalization procedure does not destroy time conservation. Even more importantly, this diagonalization significantly reduces the computational effort required to solve the LU approximation and therefore transforms it into a more efficient method of numerically solving the 3-D Euler equations.

  16. Relaxation methods for unfactored implicit upwind schemes

    NASA Technical Reports Server (NTRS)

    Chakravarthy, S. R.

    1984-01-01

    Relaxation methods are presented for unfactored implicit upwind schemes for hyperbolic equations. The theoretical bases are explained using linear and nonlinear scalar equations; construction of the method for the unsteady Euler equations (nonlinear system) is but a natural extension. One of the important advantages of the above methods vis a vis factored implicit schemes is the possibility of faster convergence to steady state, as illustrated by the results. Several classes of relaxation schemes such as pointwise, linewise, Gauss-Seidel, and non-Gauss-Seidel methods are discussed, along with various strategies for convergence.

  17. Graph state-based quantum authentication scheme

    NASA Astrophysics Data System (ADS)

    Liao, Longxia; Peng, Xiaoqi; Shi, Jinjing; Guo, Ying

    2017-04-01

    Inspired by the special properties of the graph state, a quantum authentication scheme is proposed in this paper, which is implemented with the utilization of the graph state. Two entities, a reliable party, Trent, as a verifier and Alice as prover are included. Trent is responsible for registering Alice in the beginning and confirming Alice in the end. The proposed scheme is simple in structure and convenient to realize in the realistic physical system due to the use of the graph state in a one-way quantum channel. In addition, the security of the scheme is extensively analyzed and accordingly can resist the general individual attack strategies.

  18. A concatenated coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Lin, S.

    1985-01-01

    A concatenated coding scheme for error contol in data communications was analyzed. The inner code is used for both error correction and detection, however the outer code is used only for error detection. A retransmission is requested if either the inner code decoder fails to make a successful decoding or the outer code decoder detects the presence of errors after the inner code decoding. Probability of undetected error of the proposed scheme is derived. An efficient method for computing this probability is presented. Throughout efficiency of the proposed error control scheme incorporated with a selective repeat ARQ retransmission strategy is analyzed.

  19. Shallow cumulus processes deduced from subcloud flux measurements and parameterization schemes

    SciTech Connect

    Oetles, Z.

    1993-01-01

    The purposes of this study are to improve understanding of shallow cumulus in the planetary boundary layer (PBL), to quantitatively measure their subcloud root processes, and to link those measurements to estimates of cloud layer processes. Subcloud aircraft turbulence data for three days from the 1986 HAPEX project in southwest France is extensively analyzed. Various parameterizations of cloud layer processes are used to estimate cumulus layer effects by employing the subcloud fluxes as boundary conditions. Case 1 (5/21/86) had active cumuli; over the forest they were deep and large in diameter, but clouds over farmland were shallow and small in diameter. Case 2 (5/9/86) has also weak active cumulus with a smaller vertical depth and case 3 (6/13/86) had only forced cumuli. Four methods of decomposition of turbulence data have been employed: by land surface-cumulus regime, by proximity to clouds and clear areas, by scale, and by turbulence process types. In the presence strong active cumuli from case 1, the turbulent fluxes and energy are intensified, due to the cloud [open quotes]root[close quotes] effects. The strong active cumuli are initiated by warm-moist thermals. Since cumulus layer flux measurements were not made during the HAPEX experiment, different parameterization schemes have been used to estimate cloud layer fluxes. The schemes are: the simple cumulus flux scheme, the Betts-Miller adjustment scheme, an eddy diffusion scheme, and a new eddy diffusion scheme with counter-gradient term which is developed as a part of this study. For the strong active cumulus regime from case 1, the liquid water potential temperature and total water fluxes obtained from different parameterization schemes yield very similar results. Unlike the other parameterization schemes, the new eddy diffusion scheme with a counter-gradient term yields upward buoyancy fluxes which are in a good agreement with earlier studies.

  20. Camouflage, Color Schemes, and Cubism.

    ERIC Educational Resources Information Center

    Guhin, Paula

    2002-01-01

    Presents an art activity where students learn about Cubism and color mixing. Explains that the students create camouflaged animals after learning about the work, "Female Torso" (Pablo Picasso). Includes directions for how to create the pictures and states that the assignment can be used with students of all ages. (CMK)

  1. Password authentication scheme based on the quadratic residue problem

    NASA Astrophysics Data System (ADS)

    Ali, Muhammad Helmi; Ismail, Eddie Shahril

    2017-04-01

    In this paper, we propose a new password-authentication scheme based on quadratic residue problem with the following advantages: the scheme does not require a verification file, and the scheme can withstand replay attacks and resist from the guessing and impersonation attacks. We next discuss the advantages of our designated scheme over other schemes in terms of security and efficiency.

  2. Secure Wake-Up Scheme for WBANs

    NASA Astrophysics Data System (ADS)

    Liu, Jing-Wei; Ameen, Moshaddique Al; Kwak, Kyung-Sup

    Network life time and hence device life time is one of the fundamental metrics in wireless body area networks (WBAN). To prolong it, especially those of implanted sensors, each node must conserve its energy as much as possible. While a variety of wake-up/sleep mechanisms have been proposed, the wake-up radio potentially serves as a vehicle to introduce vulnerabilities and attacks to WBAN, eventually resulting in its malfunctions. In this paper, we propose a novel secure wake-up scheme, in which a wake-up authentication code (WAC) is employed to ensure that a BAN Node (BN) is woken up by the correct BAN Network Controller (BNC) rather than unintended users or malicious attackers. The scheme is thus particularly implemented by a two-radio architecture. We show that our scheme provides higher security while consuming less energy than the existing schemes.

  3. High-Order Energy Stable WENO Schemes

    NASA Technical Reports Server (NTRS)

    Yamaleev, Nail K.; Carpenter, Mark H.

    2009-01-01

    A third-order Energy Stable Weighted Essentially Non-Oscillatory (ESWENO) finite difference scheme developed by Yamaleev and Carpenter was proven to be stable in the energy norm for both continuous and discontinuous solutions of systems of linear hyperbolic equations. Herein, a systematic approach is presented that enables 'energy stable' modifications for existing WENO schemes of any order. The technique is demonstrated by developing a one-parameter family of fifth-order upwind-biased ESWENO schemes; ESWENO schemes up to eighth order are presented in the appendix. New weight functions are also developed that provide (1) formal consistency, (2) much faster convergence for smooth solutions with an arbitrary number of vanishing derivatives, and (3) improved resolution near strong discontinuities.

  4. Robust Synchronization Schemes for Dynamic Channel Environments

    NASA Technical Reports Server (NTRS)

    Xiong, Fugin

    2003-01-01

    Professor Xiong will investigate robust synchronization schemes for dynamic channel environment. A sliding window will be investigated for symbol timing synchronizer and an open loop carrier estimator for carrier synchronization. Matlab/Simulink will be used for modeling and simulations.

  5. Optimal Symmetric Ternary Quantum Encryption Schemes

    NASA Astrophysics Data System (ADS)

    Wang, Yu-qi; She, Kun; Huang, Ru-fen; Ouyang, Zhong

    2016-11-01

    In this paper, we present two definitions of the orthogonality and orthogonal rate of an encryption operator, and we provide a verification process for the former. Then, four improved ternary quantum encryption schemes are constructed. Compared with Scheme 1 (see Section 2.3), these four schemes demonstrate significant improvements in term of calculation and execution efficiency. Especially, under the premise of the orthogonal rate ɛ as secure parameter, Scheme 3 (see Section 4.1) shows the highest level of security among them. Through custom interpolation functions, the ternary secret key source, which is composed of the digits 0, 1 and 2, is constructed. Finally, we discuss the security of both the ternary encryption operator and the secret key source, and both of them show a high level of security and high performance in execution efficiency.

  6. The Evolution of a Training Scheme.

    ERIC Educational Resources Information Center

    Atkinson, Ken; Nicholson, Brian

    1986-01-01

    The director of Youth Training for Britain's Manpower Services Commission (MSC) traces the evolution in youth training policy during the last decade. MSC chair Bryan Nicholson explains the thinking behind the new scheme. (Author/CT)

  7. A concatenated coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Kasami, T.; Fujiwara, T.; Lin, S.

    1986-01-01

    In this paper, a concatenated coding scheme for error control in data communications is presented and analyzed. In this scheme, the inner code is used for both error correction and detection; however, the outer code is used only for error detection. A retransmission is requested if either the inner code decoder fails to make a successful decoding or the outer code decoder detects the presence of errors after the inner code decoding. Probability of undetected error (or decoding error) of the proposed scheme is derived. An efficient method for computing this probability is presented. Throughput efficiency of the proposed error control scheme incorporated with a selective-repeat ARQ retransmission strategy is also analyzed. Three specific examples are presented. One of the examples is proposed for error control in the NASA Telecommand System.

  8. ONU Power Saving Scheme for EPON System

    NASA Astrophysics Data System (ADS)

    Mukai, Hiroaki; Tano, Fumihiko; Tanaka, Masaki; Kozaki, Seiji; Yamanaka, Hideaki

    PON (Passive Optical Network) achieves FTTH (Fiber To The Home) economically, by sharing an optical fiber among plural subscribers. Recently, global climate change has been recognized as a serious near term problem. Power saving techniques for electronic devices are important. In PON system, the ONU (Optical Network Unit) power saving scheme has been studied and defined in XG-PON. In this paper, we propose an ONU power saving scheme for EPON. Then, we present an analysis of the power reduction effect and the data transmission delay caused by the ONU power saving scheme. According to the analysis, we propose an efficient provisioning method for the ONU power saving scheme which is applicable to both of XG-PON and EPON.

  9. A robust coding scheme for packet video

    NASA Technical Reports Server (NTRS)

    Chen, Yun-Chung; Sayood, Khalid; Nelson, Don J.

    1992-01-01

    A layered packet video coding algorithm based on a progressive transmission scheme is presented. The algorithm provides good compression and can handle significant packet loss with graceful degradation in the reconstruction sequence. Simulation results for various conditions are presented.

  10. The Dewey Decimal Scheme and Mathematics

    ERIC Educational Resources Information Center

    Donovan, Peter W.; And Others

    1973-01-01

    This essay criticizes the mathematical schedules of the 18th edition of the Dewey Decimal Classification Scheme and offers two alternatives suitable for college libraries that use this system. (Authors)

  11. A concatenated coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Kasami, T.; Fujiwara, T.; Lin, S.

    1986-01-01

    In this paper, a concatenated coding scheme for error control in data communications is presented and analyzed. In this scheme, the inner code is used for both error correction and detection; however, the outer code is used only for error detection. A retransmission is requested if either the inner code decoder fails to make a successful decoding or the outer code decoder detects the presence of errors after the inner code decoding. Probability of undetected error (or decoding error) of the proposed scheme is derived. An efficient method for computing this probability is presented. Throughput efficiency of the proposed error control scheme incorporated with a selective-repeat ARQ retransmission strategy is also analyzed. Three specific examples are presented. One of the examples is proposed for error control in the NASA Telecommand System.

  12. A robust coding scheme for packet video

    NASA Technical Reports Server (NTRS)

    Chen, Y. C.; Sayood, Khalid; Nelson, D. J.

    1991-01-01

    We present a layered packet video coding algorithm based on a progressive transmission scheme. The algorithm provides good compression and can handle significant packet loss with graceful degradation in the reconstruction sequence. Simulation results for various conditions are presented.

  13. Renormalization scheme dependence with renormalization group summation

    NASA Astrophysics Data System (ADS)

    McKeon, D. G. C.

    2015-08-01

    We consider all perturbative radiative corrections to the total e+e- annihilation cross section Re+e- showing how the renormalization group (RG) equation associated with the radiatively induced mass scale μ can be used to sum the logarithmic contributions in two ways. First of all, one can sum leading-log, next-to-leading-log, etc., contributions to Re+e- using in turn the one-loop, two-loop, etc., contributions to the RG function β . A second summation shows how all logarithmic corrections to Re+e- can be expressed entirely in terms of the log-independent contributions when one employs the full β -function. Next, using Stevenson's characterization of any choice of renormalization scheme by the use of the contributions to the β -function arising beyond two-loop order, we examine the RG scheme dependence in Re+e- when using the second way of summing logarithms. The renormalization scheme invariants that arise are then related to the renormalization scheme invariants found by Stevenson. We next consider two choices of the renormalization scheme, one which can be used to express Re+e- solely in terms of two powers of a running coupling, and the second which can be used to express Re+e- as an infinite series in the two-loop running coupling (i.e., a Lambert W -function). In both cases, Re+e- is expressed solely in terms of renormalization scheme invariant parameters that are to be computed by a perturbative evaluation of Re+e-. We then establish how in general the coupling constant arising in one renormalization scheme can be expressed as a power series of the coupling arising in any other scheme. We then establish how, by using a different renormalization mass scale at each order of perturbation theory, all renormalization scheme dependence can be absorbed into these mass scales when one uses the second way of summing logarithmic corrections to Re+e-. We then employ the approach to renormalization scheme dependency that we have applied to Re+e- to a RG summed

  14. Umm Qasr Water Scheme, Iraq

    DTIC Science & Technology

    2006-07-24

    cement lined, or 144 Km, which leaves 40% unlined and clay based. To compound this problem, a major shift in the construction to avoid a high gypsum area...signs of recent repair activities of the canal bank. It appeared the concrete liners were repaired with a concrete slurry applied instead of...with concrete slurry at km 168 repair area Site Photo 15. km 188 repair area Site Photo 16. Surface erosion of canal banks at km 188 repair area

  15. Matching Multistage Schemes to Viscous Flow

    NASA Technical Reports Server (NTRS)

    Kleb, William L.; VanLeer, Bram; Wood, William A.

    2005-01-01

    Multistage, explicit time stepping can be tailored to accelerate convergence for scalar advection-diffusion problems by using optimized multistage coefficients that vary with the local cell Reynolds number. And, when combined with local preconditioning, variable-coefficient multistage schemes for computational fluid dynamics codes can also provide an order of magnitude faster convergence, relative to standard, fixed-coefficient schemes, for the Navier-Stokes system of equations.

  16. Simplified Learning Scheme For Analog Neural Network

    NASA Technical Reports Server (NTRS)

    Eberhardt, Silvio P.

    1991-01-01

    Synaptic connections adjusted one at a time in small increments. Simplified gradient-descent learning scheme for electronic neural-network processor less efficient than better-known back-propagation scheme, but offers two advantages: easily implemented in circuitry because data-access circuitry separated from learning circuitry; and independence of data-access circuitry makes possible to implement feedforward as well as feedback networks, including those of multiple-attractor type. Important in such applications as recognition of patterns.

  17. Asynchronous Communication Scheme For Hypercube Computer

    NASA Technical Reports Server (NTRS)

    Madan, Herb S.

    1988-01-01

    Scheme devised for asynchronous-message communication system for Mark III hypercube concurrent-processor network. Network consists of up to 1,024 processing elements connected electrically as though were at corners of 10-dimensional cube. Each node contains two Motorola 68020 processors along with Motorola 68881 floating-point processor utilizing up to 4 megabytes of shared dynamic random-access memory. Scheme intended to support applications requiring passage of both polled or solicited and unsolicited messages.

  18. Dynamic Restarting Schemes for Eigenvalue Problems

    SciTech Connect

    Wu, Kesheng; Simon, Horst D.

    1999-03-10

    In studies of restarted Davidson method, a dynamic thick-restart scheme was found to be excellent in improving the overall effectiveness of the eigen value method. This paper extends the study of the dynamic thick-restart scheme to the Lanczos method for symmetric eigen value problems and systematically explore a range of heuristics and strategies. We conduct a series of numerical tests to determine their relative strength and weakness on a class of electronic structure calculation problems.

  19. Finance schemes for funding private orthodontic treatment.

    PubMed

    Perks, S

    1997-02-01

    Over the last ten years there has been a steady increase in the volume of private dental treatment and numerous finance schemes have been developed to help both patients and dentists. Private orthodontic treatment is increasing and the purpose of this article is to summarise the main features of the schemes currently available to fund private orthodontic treatment and to provide a source of reference.

  20. Motion-based wake-up scheme for ambulatory monitoring in wireless body sensor networks.

    PubMed

    Pek, Isaac; Waluyo, Agustinus Borgy; Yeoh, Wee-Soon; Chen, Xiang

    2009-01-01

    Given that wearable sensors that are attached on patients for the purpose of continuous real-time medical monitoring typically need to remain operational for periods of up to 24 hours before a battery change or recharge, power preservation schemes play a critical role in minimizing any possible disruption to a patient's daily activities. In this paper, we propose a motion-based wake-up scheme, a feature which combines motion detection with existing power preservation schemes in order to achieve a balance between energy saving and data timeliness, particularly in critical situations. As a showcase, we have integrated this feature with a healthcare application and demonstrate the capability of the scheme to deal with critical events, e.g., when a patient falls down from the bed. This showcase affirms the effective uses of our proposed motion-based wake-up scheme.

  1. A novel chemical scheme for flotation of rutile from eclogite tailing

    NASA Astrophysics Data System (ADS)

    Xu, Bo; Liu, Shuang; Li, Hongqiang; Zhao, Yunliang; Li, Hongchao; Song, Shaoxian

    A novel chemical scheme for the flotation of rutile from eclogite tailings has been developed in this work. It consists of lead ion as the activator, sodium fluorosilicate (SF) as the depressant, and styryl phosphonic acid (SPA) and n-octyl alcohol (OCT) as the collector. By using the proposed scheme to treat a feed ore of 4.5% TiO2, a rougher concentrate of grade 84.47% TiO2 was achieved with the recovery of 61.5%. Also, the scheme made a high flotation rate for rutile. The scheme was applied to closed-circuit flotation (one-stage rougher flotation, two-stage scavenger flotation and two-stage cleaner flotation), produced a concentrate of 92% TiO2 with the recovery of 70%. It is shown that the new chemical scheme would be a potential one for the effective separation of rutile from eclogite ores.

  2. Module partitioning and interlaced data placement schemes to reduce conflicts in interleaved memories

    SciTech Connect

    Kurian, L.; Choi, B.; Hulina, P.T.; Coraor, L.D.

    1994-12-31

    In interleaved memories, interference between concurrently active vector streams results in memory bank conflicts and reduced bandwidth. In this paper, we present two schemes for reducing inter-vector interference. First, we propose a memory module partitioning technique in which disjoint access sets are created for each of the concurrent vectors. Various properties of the involved address mapping are presented. Then we present an interlaced data placement scheme, where the simultaneously accessed vectors are interlaced and stored to the memory. Performance of the two schemes are evaluated by trace driven simulation. It is observed that the schemes have significant merit in reducing the interference in interleaved memories and increasingly the effective memory bandwidth. The schemes are applicable to memory systems for superscalar processors, vector supercomputers and parallel processors.

  3. Twin-Schnorr: A Security Upgrade for the Schnorr Identity-Based Identification Scheme

    PubMed Central

    Heng, Swee-Huay; Phan, Raphael Chung-Wei

    2015-01-01

    Most identity-based identification (IBI) schemes proposed in recent literature are built using pairing operations. This decreases efficiency due to the high operation costs of pairings. Furthermore, most of these IBI schemes are proven to be secure against impersonation under active and concurrent attacks using interactive assumptions such as the one-more RSA inversion assumption or the one-more discrete logarithm assumption, translating to weaker security guarantees due to the interactive nature of these assumptions. The Schnorr-IBI scheme was first proposed through the Kurosawa-Heng transformation from the Schnorr signature. It remains one of the fastest yet most secure IBI schemes under impersonation against passive attacks due to its pairing-free design. However, when required to be secure against impersonators under active and concurrent attacks, it deteriorates greatly in terms of efficiency due to the protocol having to be repeated multiple times. In this paper, we upgrade the Schnorr-IBI scheme to be secure against impersonation under active and concurrent attacks using only the classical discrete logarithm assumption. This translates to a higher degree of security guarantee with only some minor increments in operational costs. Furthermore, because the scheme operates without pairings, it still retains its efficiency and superiority when compared to other pairing-based IBI schemes. PMID:25692179

  4. Twin-Schnorr: a security upgrade for the Schnorr identity-based identification scheme.

    PubMed

    Chin, Ji-Jian; Tan, Syh-Yuan; Heng, Swee-Huay; Phan, Raphael Chung-Wei

    2015-01-01

    Most identity-based identification (IBI) schemes proposed in recent literature are built using pairing operations. This decreases efficiency due to the high operation costs of pairings. Furthermore, most of these IBI schemes are proven to be secure against impersonation under active and concurrent attacks using interactive assumptions such as the one-more RSA inversion assumption or the one-more discrete logarithm assumption, translating to weaker security guarantees due to the interactive nature of these assumptions. The Schnorr-IBI scheme was first proposed through the Kurosawa-Heng transformation from the Schnorr signature. It remains one of the fastest yet most secure IBI schemes under impersonation against passive attacks due to its pairing-free design. However, when required to be secure against impersonators under active and concurrent attacks, it deteriorates greatly in terms of efficiency due to the protocol having to be repeated multiple times. In this paper, we upgrade the Schnorr-IBI scheme to be secure against impersonation under active and concurrent attacks using only the classical discrete logarithm assumption. This translates to a higher degree of security guarantee with only some minor increments in operational costs. Furthermore, because the scheme operates without pairings, it still retains its efficiency and superiority when compared to other pairing-based IBI schemes.

  5. FRESCO: flexible alignment with rectangle scoring schemes.

    PubMed

    Dalca, A V; Brudno, M

    2008-01-01

    While the popular DNA sequence alignment tools incorporate powerful heuristics to allow for fast and accurate alignment of DNA, most of them still optimize the classical Needleman Wunsch scoring scheme. The development of novel scoring schemes is often hampered by the difficulty of finding an optimizing algorithm for each non-trivial scheme. In this paper we define the broad class of rectangle scoring schemes, and describe an algorithm and tool that can align two sequences with an arbitrary rectangle scoring scheme in polynomial time. Rectangle scoring schemes encompass some of the popular alignment scoring metrics currently in use, as well as many other functions. We investigate a novel scoring function based on minimizing the expected number of random diagonals observed with the given scores and show that it rivals the LAGAN and Clustal-W aligners, without using any biological or evolutionary parameters. The FRESCO program, freely available at http://compbio.cs.toronto.edu/fresco, gives bioinformatics researchers the ability to quickly compare the performance of other complex scoring formulas without having to implement new algorithms to optimize them.

  6. Efficient multiparty quantum-secret-sharing schemes

    SciTech Connect

    Xiao Li; Deng Fuguo; Long Guilu; Pan Jianwei

    2004-05-01

    In this work, we generalize the quantum-secret-sharing scheme of Hillery, Buzek, and Berthiaume [Phys. Rev. A 59, 1829 (1999)] into arbitrary multiparties. Explicit expressions for the shared secret bit is given. It is shown that in the Hillery-Buzek-Berthiaume quantum-secret-sharing scheme the secret information is shared in the parity of binary strings formed by the measured outcomes of the participants. In addition, we have increased the efficiency of the quantum-secret-sharing scheme by generalizing two techniques from quantum key distribution. The favored-measuring-basis quantum-secret-sharing scheme is developed from the Lo-Chau-Ardehali technique [H. K. Lo, H. F. Chau, and M. Ardehali, e-print quant-ph/0011056] where all the participants choose their measuring-basis asymmetrically, and the measuring-basis-encrypted quantum-secret-sharing scheme is developed from the Hwang-Koh-Han technique [W. Y. Hwang, I. G. Koh, and Y. D. Han, Phys. Lett. A 244, 489 (1998)] where all participants choose their measuring basis according to a control key. Both schemes are asymptotically 100% in efficiency, hence nearly all the Greenberger-Horne-Zeilinger states in a quantum-secret-sharing process are used to generate shared secret information.

  7. Simplification of the unified gas kinetic scheme

    NASA Astrophysics Data System (ADS)

    Chen, Songze; Guo, Zhaoli; Xu, Kun

    2016-08-01

    The unified gas kinetic scheme (UGKS) is an asymptotic preserving (AP) scheme for kinetic equations. It is superior for transition flow simulation and has been validated in the past years. However, compared to the well-known discrete ordinate method (DOM), which is a classical numerical method solving the kinetic equations, the UGKS needs more computational resources. In this study, we propose a simplification of the unified gas kinetic scheme. It allows almost identical numerical cost as the DOM, but predicts numerical results as accurate as the UGKS. In the simplified scheme, the numerical flux for the velocity distribution function and the numerical flux for the macroscopic conservative quantities are evaluated separately. The equilibrium part of the UGKS flux is calculated by analytical solution instead of the numerical quadrature in velocity space. The simplification is equivalent to a flux hybridization of the gas kinetic scheme for the Navier-Stokes (NS) equations and the conventional discrete ordinate method. Several simplification strategies are tested, through which we can identify the key ingredient of the Navier-Stokes asymptotic preserving property. Numerical tests show that, as long as the collision effect is built into the macroscopic numerical flux, the numerical scheme is Navier-Stokes asymptotic preserving, regardless the accuracy of the microscopic numerical flux for the velocity distribution function.

  8. Access and accounting schemes of wireless broadband

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Huang, Benxiong; Wang, Yan; Yu, Xing

    2004-04-01

    In this paper, two wireless broadband access and accounting schemes were introduced. There are some differences in the client and the access router module between them. In one scheme, Secure Shell (SSH) protocol is used in the access system. The SSH server makes the authentication based on private key cryptography. The advantage of this scheme is the security of the user's information, and we have sophisticated access control. In the other scheme, Secure Sockets Layer (SSL) protocol is used the access system. It uses the technology of public privacy key. Nowadays, web browser generally combines HTTP and SSL protocol and we use the SSL protocol to implement the encryption of the data between the clients and the access route. The schemes are same in the radius sever part. Remote Authentication Dial in User Service (RADIUS), as a security protocol in the form of Client/Sever, is becoming an authentication/accounting protocol for standard access to the Internet. It will be explained in a flow chart. In our scheme, the access router serves as the client to the radius server.

  9. A factorial assessment of the sensitivity of the BATS land-surface parameterization scheme. [BATS (Biosphere-Atmosphere Transfer Scheme)

    SciTech Connect

    Henderson-Sellers, A. )

    1993-02-01

    Land-surface schemes developed for incorporation into global climate models include parameterizations that are not yet fully validated and depend upon the specification of a large (20-50) number of ecological and soil parameters, the values of which are not yet well known. There are two methods of investigating the sensitivity of a land-surface scheme to prescribed values: simple one-at-a-time changes or factorial experiments. Factorial experiments offer information about interactions between parameters and are thus a more powerful tool. Here the results of a suite of factorial experiments are reported. These are designed (i) to illustrate the usefulness of this methodology and (ii) to identify factors important to the performance of complex land-surface schemes. The Biosphere-Atmosphere Transfer Scheme (BATS) is used and its sensitivity is considered (a) to prescribed ecological and soil parameters and (b) to atmospheric forcing used in the off-line tests undertaken. Results indicate that the most important atmospheric forcings are mean monthly temperature and the interaction between mean monthly temperature and total monthly precipitation, although fractional cloudiness and other parameters are also important. The most important ecological parameters are vegetation roughness length, soil porosity, and a factor describing the sensitivity of the stomatal resistance of vegetation to the amount of photosynthetically active solar radiation and, to a lesser extent, soil and vegetation albedos. Two-factor interactions including vegetation roughness length are more important than many of the 23 specified single factors. The results of factorial sensitivity experiments such as these could form the basis for intercomparison of land-surface parameterization schemes and for field experiments and satellite-based observation programs aimed at improving evaluation of important parameters.

  10. Passive Phase Noise Cancellation Scheme

    PubMed Central

    Kenig, Eyal; Cross, M. C.; Lifshitz, Ron; Karabalin, R. B.; Villanueva, L. G.; Matheny, M. H.; Roukes, M. L.

    2013-01-01

    We introduce a new method for reducing phase noise in oscillators, thereby improving their frequency precision. The noise reduction is realized by a passive device consisting of a pair of coupled nonlinear resonating elements that are driven parametrically by the output of a conventional oscillator at a frequency close to the sum of the linear mode frequencies. Above the threshold for parametric instability, the coupled resonators exhibit self-oscillations which arise as a response to the parametric driving, rather than by application of active feedback. We find operating points of the device for which this periodic signal is immune to frequency noise in the driving oscillator, providing a way to clean its phase noise. We present results for the effect of thermal noise to advance a broader understanding of the overall noise sensitivity and the fundamental operating limits. PMID:23004985

  11. PRICE: primitive centred schemes for hyperbolic systems

    NASA Astrophysics Data System (ADS)

    Toro, E. F.; Siviglia, A.

    2003-08-01

    We present first- and higher-order non-oscillatory primitive (PRI) centred (CE) numerical schemes for solving systems of hyperbolic partial differential equations written in primitive (or non-conservative) form. Non-conservative systems arise in a variety of fields of application and they are adopted in that form for numerical convenience, or more importantly, because they do not posses a known conservative form; in the latter case there is no option but to apply non-conservative methods. In addition we have chosen a centred, as distinct from upwind, philosophy. This is because the systems we are ultimately interested in (e.g. mud flows, multiphase flows) are exceedingly complicated and the eigenstructure is difficult, or very costly or simply impossible to obtain. We derive six new basic schemes and then we study two ways of extending the most successful of these to produce second-order non-oscillatory methods. We have used the MUSCL-Hancock and the ADER approaches. In the ADER approach we have used two ways of dealing with linear reconstructions so as to avoid spurious oscillations: the ADER TVD scheme and ADER with ENO reconstruction. Extensive numerical experiments suggest that all the schemes are very satisfactory, with the ADER/ENO scheme being perhaps the most promising, first for dealing with source terms and secondly, because higher-order extensions (greater than two) are possible. Work currently in progress includes the application of some of these ideas to solve the mud flow equations. The schemes presented are generic and can be applied to any hyperbolic system in non-conservative form and for which solutions include smooth parts, contact discontinuities and weak shocks. The advantage of the schemes presented over upwind-based methods is simplicity and efficiency, and will be fully realized for hyperbolic systems in which the provision of upwind information is very costly or is not available.

  12. Combining image-processing and image compression schemes

    NASA Technical Reports Server (NTRS)

    Greenspan, H.; Lee, M.-C.

    1995-01-01

    An investigation into the combining of image-processing schemes, specifically an image enhancement scheme, with existing compression schemes is discussed. Results are presented on the pyramid coding scheme, the subband coding scheme, and progressive transmission. Encouraging results are demonstrated for the combination of image enhancement and pyramid image coding schemes, especially at low bit rates. Adding the enhancement scheme to progressive image transmission allows enhanced visual perception at low resolutions. In addition, further progressing of the transmitted images, such as edge detection schemes, can gain from the added image resolution via the enhancement.

  13. Combining image-processing and image compression schemes

    NASA Technical Reports Server (NTRS)

    Greenspan, H.; Lee, M.-C.

    1995-01-01

    An investigation into the combining of image-processing schemes, specifically an image enhancement scheme, with existing compression schemes is discussed. Results are presented on the pyramid coding scheme, the subband coding scheme, and progressive transmission. Encouraging results are demonstrated for the combination of image enhancement and pyramid image coding schemes, especially at low bit rates. Adding the enhancement scheme to progressive image transmission allows enhanced visual perception at low resolutions. In addition, further progressing of the transmitted images, such as edge detection schemes, can gain from the added image resolution via the enhancement.

  14. A classification scheme for risk assessment methods.

    SciTech Connect

    Stamp, Jason Edwin; Campbell, Philip LaRoche

    2004-08-01

    This report presents a classification scheme for risk assessment methods. This scheme, like all classification schemes, provides meaning by imposing a structure that identifies relationships. Our scheme is based on two orthogonal aspects--level of detail, and approach. The resulting structure is shown in Table 1 and is explained in the body of the report. Each cell in the Table represent a different arrangement of strengths and weaknesses. Those arrangements shift gradually as one moves through the table, each cell optimal for a particular situation. The intention of this report is to enable informed use of the methods so that a method chosen is optimal for a situation given. This report imposes structure on the set of risk assessment methods in order to reveal their relationships and thus optimize their usage.We present a two-dimensional structure in the form of a matrix, using three abstraction levels for the rows and three approaches for the columns. For each of the nine cells in the matrix we identify the method type by name and example. The matrix helps the user understand: (1) what to expect from a given method, (2) how it relates to other methods, and (3) how best to use it. Each cell in the matrix represent a different arrangement of strengths and weaknesses. Those arrangements shift gradually as one moves through the table, each cell optimal for a particular situation. The intention of this report is to enable informed use of the methods so that a method chosen is optimal for a situation given. The matrix, with type names in the cells, is introduced in Table 2 on page 13 below. Unless otherwise stated we use the word 'method' in this report to refer to a 'risk assessment method', though often times we use the full phrase. The use of the terms 'risk assessment' and 'risk management' are close enough that we do not attempt to distinguish them in this report. The remainder of this report is organized as follows. In Section 2 we provide context for this report

  15. Identification Schemes from Key Encapsulation Mechanisms

    NASA Astrophysics Data System (ADS)

    Anada, Hiroaki; Arita, Seiko

    We propose a generic conversion from a key encapsulation mechanism (KEM) to an identification (ID) scheme. The conversion derives the security for ID schemes against concurrent man-in-the-middle (cMiM) attacks from the security for KEMs against adaptive chosen ciphertext attacks on one-wayness (one-way-CCA2). Then, regarding the derivation as a design principle of ID schemes, we develop a series of concrete one-way-CCA2 secure KEMs. We start with El Gamal KEM and prove it secure against non-adaptive chosen ciphertext attacks on one-wayness (one-way-CCA1) in the standard model. Then, we apply a tag framework with the algebraic trick of Boneh and Boyen to make it one-way-CCA2 secure based on the Gap-CDH assumption. Next, we apply the CHK transformation or a target collision resistant hash function to exit the tag framework. And finally, as it is better to rely on the CDH assumption rather than the Gap-CDH assumption, we apply the Twin DH technique of Cash, Kiltz and Shoup. The application is not “black box” and we do it by making the Twin DH technique compatible with the algebraic trick. The ID schemes obtained from our KEMs show the highest performance in both computational amount and message length compared with previously known ID schemes secure against concurrent man-in-the-middle attacks.

  16. Scientific review of the Welfare Food Scheme.

    PubMed

    2002-01-01

    The COMA Panel on Maternal and Child Nutrition has undertaken the first scientific review of the Welfare Food Scheme since its inception in 1940. It has: reviewed current dietary recommendations, identified from national data, population groups vulnerable to adverse nutritional outcomes, evaluated the contribution of the current scheme to prevention of these vulnerabilities and identified further information needs and highlighted improvements likely to be cost neutral. Originally the Scheme incorporated universal provision. Subsequently it was targeted at the most socio-economically vulnerable. Today, a quarter of children under five are beneficiaries by virtue of their family's income. The Scheme has two principal beneficiary groups: pregnant women, mothers and young chidren in families eligible for certain social security benefits. With the exception of children under one year of age, all are entitled to a pint of milk a day (using redeemable milk tokens) and free vitamin supplements (available from designated clinics). Infant formula instead of milk is available for infants who are not breastfed. children under five years attending Scheme-registered day care facilities can receive one third of a pint of milk a day. Children aged 5-16 years not registered at school by virtue of mental or physical disability are entitled to a pint of milk a day. The following adverse nutritional outcomes were considered: pregnant women and mothers low uptake of periconceptional folic acid supplements low dietary intake during pregnancy vitamin D deficiency.

  17. Selecting optimal partitioning schemes for phylogenomic datasets.

    PubMed

    Lanfear, Robert; Calcott, Brett; Kainer, David; Mayer, Christoph; Stamatakis, Alexandros

    2014-04-17

    Partitioning involves estimating independent models of molecular evolution for different subsets of sites in a sequence alignment, and has been shown to improve phylogenetic inference. Current methods for estimating best-fit partitioning schemes, however, are only computationally feasible with datasets of fewer than 100 loci. This is a problem because datasets with thousands of loci are increasingly common in phylogenetics. We develop two novel methods for estimating best-fit partitioning schemes on large phylogenomic datasets: strict and relaxed hierarchical clustering. These methods use information from the underlying data to cluster together similar subsets of sites in an alignment, and build on clustering approaches that have been proposed elsewhere. We compare the performance of our methods to each other, and to existing methods for selecting partitioning schemes. We demonstrate that while strict hierarchical clustering has the best computational efficiency on very large datasets, relaxed hierarchical clustering provides scalable efficiency and returns dramatically better partitioning schemes as assessed by common criteria such as AICc and BIC scores. These two methods provide the best current approaches to inferring partitioning schemes for very large datasets. We provide free open-source implementations of the methods in the PartitionFinder software. We hope that the use of these methods will help to improve the inferences made from large phylogenomic datasets.

  18. Self-protection scheme against failures of distributed fiber links in an Ethernet passive optical network

    NASA Astrophysics Data System (ADS)

    Chen, Jiajia; Chen, Biao; He, Sailing

    2006-09-01

    A novel self-protection scheme for an Ethernet passive optical network is introduced and studied at both the physical and the media access control layers. The scheme is simple and fast and can provide 1:1 protection and automatic traffic restoration against the fiber link failure between a remote node (RN) and any optical network unit (ONU). Simulation results show that fiber failure does not degrade the transmission performance, and the restoration time depends mainly on the switch time of the physical layer. Our protection scheme saves many long fibers, does not influence other normal ONUs, and requires no active device in the RN.

  19. Explicit and implicit finite difference schemes for fractional Cattaneo equation

    NASA Astrophysics Data System (ADS)

    Ghazizadeh, H. R.; Maerefat, M.; Azimi, A.

    2010-09-01

    In this paper, the numerical solution of fractional (non-integer)-order Cattaneo equation for describing anomalous diffusion has been investigated. Two finite difference schemes namely an explicit predictor-corrector and totally implicit schemes have been developed. In developing each scheme, a separate formulation approach for the governing equations has been considered. The explicit predictor-corrector scheme is the fractional generalization of well-known MacCormack scheme and has been called Generalized MacCormack scheme. This scheme solves two coupled low-order equations and simultaneously computes the flux term with the main variable. Fully implicit scheme however solves a single high-order undecomposed equation. For Generalized MacCormack scheme, stability analysis has been studied through Fourier method. Through a numerical test, the experimental order of convergency of both schemes has been found. Then, the domain of applicability and some numerical properties of each scheme have been discussed.

  20. Scheme variations of the QCD coupling

    NASA Astrophysics Data System (ADS)

    Boito, Diogo; Jamin, Matthias; Miravitllas, Ramon

    2017-03-01

    The Quantum Chromodynamics (QCD) coupling αs is a central parameter in the Standard Model of particle physics. However, it depends on theoretical conventions related to renormalisation and hence is not an observable quantity. In order to capture this dependence in a transparent way, a novel definition of the QCD coupling, denoted by â, is introduced, whose running is explicitly renormalisation scheme invariant. The remaining renormalisation scheme dependence is related to transformations of the QCD scale Λ, and can be parametrised by a single parameter C. Hence, we call â the C-scheme coupling. The dependence on C can be exploited to study and improve perturbative predictions of physical observables. This is demonstrated for the QCD Adler function and hadronic decays of the τ lepton.

  1. Physical Renormalization Schemes and Grand Unification

    SciTech Connect

    Binger, M.

    2003-11-07

    In a physical renormalization scheme, gauge couplings are defined directly in terms of physical observables. Such effective charges are analytic functions of physical scales, and thus mass thresholds are treated with their correct analytic dependence. In particular, particles will contribute to physical predictions even at energies below their threshold. This is in contrast to unphysical renormalization schemes such as {ovr MS} where mass thresholds are treated as step functions. In this paper we analyze supersymmetric grand unification in the context of physical renormalization schemes and find a number of qualitative differences and improvements in precision over conventional approaches. The effective charge formalism presented here provides a template for calculating all mass threshold effects for any given grand unified theory. These new threshold corrections may be important in making the measured values of the gauge couplings consistent with unification.

  2. Asynchronous discrete event schemes for PDEs

    NASA Astrophysics Data System (ADS)

    Stone, D.; Geiger, S.; Lord, G. J.

    2017-08-01

    A new class of asynchronous discrete-event simulation schemes for advection-diffusion-reaction equations is introduced, based on the principle of allowing quanta of mass to pass through faces of a (regular, structured) Cartesian finite volume grid. The timescales of these events are linked to the flux on the face. The resulting schemes are self-adaptive, and local in both time and space. Experiments are performed on realistic physical systems related to porous media flow applications, including a large 3D advection diffusion equation and advection diffusion reaction systems. The results are compared to highly accurate reference solutions where the temporal evolution is computed with exponential integrator schemes using the same finite volume discretisation. This allows a reliable estimation of the solution error. Our results indicate a first order convergence of the error as a control parameter is decreased, and we outline a framework for analysis.

  3. Progressive classification scheme for document layout recognition

    NASA Astrophysics Data System (ADS)

    Minguillon, Julian; Pujol, Jaume; Zeger, Kenneth

    1999-06-01

    In this paper, we present a progressive classification scheme for a document layout recognition system using three stages. The first stages, preprocessing, extracts statistical information that may be used for background detection and removal. The second stage, a tree based classified, uses a variable block size and a set of probabilistic rules to classify segmented blocks that are independently classified. The third, state, postprocessing, uses the label map generated in the second state with a set of context rules to label unclassified blocks, trying also to solve some of the misclassification errors that may have been generated during the previous stage. The progressive scheme used in the second and third stages allows the user to stop the classification process at any block size, depending on this requirements. Experiments show that a progressive scheme combined with a set of postprocessing rules increases the percentage of correctly classified blocks and reduces the number of block computations.

  4. Cooling scheme for turbine hot parts

    DOEpatents

    Hultgren, Kent Goran; Owen, Brian Charles; Dowman, Steven Wayne; Nordlund, Raymond Scott; Smith, Ricky Lee

    2000-01-01

    A closed-loop cooling scheme for cooling stationary combustion turbine components, such as vanes, ring segments and transitions, is provided. The cooling scheme comprises: (1) an annular coolant inlet chamber, situated between the cylinder and blade ring of a turbine, for housing coolant before being distributed to the turbine components; (2) an annular coolant exhaust chamber, situated between the cylinder and the blade ring and proximate the annular coolant inlet chamber, for collecting coolant exhaust from the turbine components; (3) a coolant inlet conduit for supplying the coolant to said coolant inlet chamber; (4) a coolant exhaust conduit for directing coolant from said coolant exhaust chamber; and (5) a piping arrangement for distributing the coolant to and directing coolant exhaust from the turbine components. In preferred embodiments of the invention, the cooling scheme further comprises static seals for sealing the blade ring to the cylinder and flexible joints for attaching the blade ring to the turbine components.

  5. High order well-balanced schemes

    SciTech Connect

    Noelle, Sebastian; Xing, Yulong; Shu, Chi-wang

    2010-01-01

    In this paper the authors review some recent work on high-order well-balanced schemes. A characteristic feature of hyperbolic systems of balance laws is the existence of non-trivial equilibrium solutions, where the effects of convective fluxes and source terms cancel each other. Well-balanced schemes satisfy a discrete analogue of this balance and are therefore able to maintain an equilibrium state. They discuss two classes of schemes, one based on high-order accurate, non-oscillatory finite difference operators which are well-balanced for a general class of equilibria, and the other one based on well-balanced quadratures, which can - in principle - be applied to all equilibria. Applications include equilibria at rest, where the flow velocity vanishes, and also the more challenging moving flow equilibria. Numerical experiments show excellent resolution of unperturbed as well as slightly perturbed equilibria.

  6. Vector lifting schemes for stereo image coding.

    PubMed

    Kaaniche, Mounir; Benazza-Benyahia, Amel; Pesquet-Popescu, Béatrice; Pesquet, Jean-Christophe

    2009-11-01

    Many research efforts have been devoted to the improvement of stereo image coding techniques for storage or transmission. In this paper, we are mainly interested in lossy-to-lossless coding schemes for stereo images allowing progressive reconstruction. The most commonly used approaches for stereo compression are based on disparity compensation techniques. The basic principle involved in this technique first consists of estimating the disparity map. Then, one image is considered as a reference and the other is predicted in order to generate a residual image. In this paper, we propose a novel approach, based on vector lifting schemes (VLS), which offers the advantage of generating two compact multiresolution representations of the left and the right views. We present two versions of this new scheme. A theoretical analysis of the performance of the considered VLS is also conducted. Experimental results indicate a significant improvement using the proposed structures compared with conventional methods.

  7. Upwind and symmetric shock-capturing schemes

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    1987-01-01

    The development of numerical methods for hyperbolic conservation laws has been a rapidly growing area for the last ten years. Many of the fundamental concepts and state-of-the-art developments can only be found in meeting proceedings or internal reports. This review paper attempts to give an overview and a unified formulation of a class of shock-capturing methods. Special emphasis is on the construction of the basic nonlinear scalar second-order schemes and the methods of extending these nonlinear scalar schemes to nonlinear systems via the extact Riemann solver, approximate Riemann solvers, and flux-vector splitting approaches. Generalization of these methods to efficiently include real gases and large systems of nonequilibrium flows is discussed. The performance of some of these schemes is illustrated by numerical examples for one-, two- and three-dimensional gas dynamics problems.

  8. Matching multistage schemes to viscous flow

    NASA Astrophysics Data System (ADS)

    Kleb, William Leonard

    A method to accelerate convergence to steady state by explicit time-marching schemes for the compressible Navier-Stokes equations is presented. The combination of cell-Reynolds-number-based multistage time stepping and local preconditioning makes solving steady-state viscous flow problems competitive with the convergence rates typically associated with implicit methods, without the associated memory penalty. Initially, various methods are investigated to extend the range of multistage schemes to diffusion-dominated cases. It is determined that the Chebyshev polynomials are well suited to serve as amplification factors for these schemes; however, creating a method that can bridge the continuum from convection-dominated to diffusion-dominated regimes proves troublesome, until the Manteuffel family of polynomials is uncovered. This transformation provides a smooth transition between the two extremes; and armed with this information, sets of multistage coefficients are created for a given spatial discretization as a function of cell Reynolds number according to various design criteria. As part of this process, a precise definition for the numerical time step is hammered out, something which up to this time, has been set via algebraic arguments only. Next are numerical tests of these sets of variable multistage coefficients. To isolate the effects of the variable multistage coefficients, the test case chosen is very simple: circular advection-diffusion. The numerical results support the analytical analysis by demonstrating an order of magnitude improvement in convergence rate for single-grid relaxation and a factor of three for multigrid relaxation. Building upon the success of the scalar case, preconditioning is applied to make the Navier-Stokes system of equations behave more nearly as a single scalar equation. Then, by applying the variable multistage coefficient scheme to a typical boundary-layer flow problem, the results affirm the benefits of local preconditioning

  9. Nuclear gamma-ray laser: A comparative analysis of various schemes

    NASA Astrophysics Data System (ADS)

    Rivlin, L. A.; Zadernovsky, A. A.

    2010-05-01

    Four basic schemes for a nuclear gamma-ray laser (NGL) are analyzed using the “NGL-hyper-bola” as a generalized comparative criterion: solid state Mössbauer scheme; stimulated gamma-emission in cooled ensembles of free nuclei with hidden population inversion of nuclear states; nuclear gamma-ray lasing without inversion; and Bose-Einstein condensate as a hypothetical active medium for NGL.

  10. Fast DPCM scheme for lossless compression of aurora spectral images

    NASA Astrophysics Data System (ADS)

    Kong, Wanqiu; Wu, Jiaji

    2016-10-01

    Aurora has abundant information to be stored. Aurora spectral image electronically preserves spectral information and visual observation of aurora during a period to be studied later. These images are helpful for the research of earth-solar activities and to understand the aurora phenomenon itself. However, the images are produced with a quite high sampling frequency, which leads to the challenging transmission load. In order to solve the problem, lossless compression turns out to be required. Indeed, each frame of aurora spectral images differs from the classical natural image and also from the frame of hyperspectral image. Existing lossless compression algorithms are not quite applicable. On the other hand, the key of compression is to decorrelate between pixels. We consider exploiting a DPCM-based scheme for the lossless compression because DPCM is effective for decorrelation. Such scheme makes use of two-dimensional redundancy both in the spatial and spectral domain with a relatively low complexity. Besides, we also parallel it for a faster computation speed. All codes are implemented on a structure consists of nested for loops of which the outer and the inner loops are respectively designed for spectral and spatial decorrelation. And the parallel version is represented on CPU platform using different numbers of cores. Experimental results show that compared to traditional lossless compression methods, the DPCM scheme has great advantage in compression gain and meets the requirement of real-time transmission. Besides, the parallel version has expected computation performance with a high CPU utilization.

  11. The Project for Intercomparison of Land-surface Parameterization Schemes

    NASA Technical Reports Server (NTRS)

    Henderson-Sellers, A.; Yang, Z.-L.; Dickinson, R. E.

    1993-01-01

    The Project for Intercomparison of Land-surface Parameterization Schemes (PILPS) is described and the first stage science plan outlined. PILPS is a project designed to improve the parameterization of the continental surface, especially the hydrological, energy, momentum, and carbon exchanges with the atmosphere. The PILPS Science Plan incorporates enhanced documentation, comparison, and validation of continental surface parameterization schemes by community participation. Potential participants include code developers, code users, and those who can provide datasets for validation and who have expertise of value in this exercise. PILPS is an important activity because existing intercomparisons, although piecemeal, demonstrate that there are significant differences in the formulation of individual processes in the available land surface schemes. These differences are comparable to other recognized differences among current global climate models such as cloud and convection parameterizations. It is also clear that too few sensitivity studies have been undertaken with the result that there is not yet enough information to indicate which simplifications or omissions are important for the near-surface continental climate, hydrology, and biogeochemistry. PILPS emphasizes sensitivity studies with and intercomparisons of existing land surface codes and the development of areally extensive datasets for their testing and validation.

  12. Calculation of photoelectron spectra: A mean-field-based scheme

    NASA Astrophysics Data System (ADS)

    Dinh, P. M.; Romaniello, P.; Reinhard, P.-G.; Suraud, E.

    2013-03-01

    In a previous work, Pohl [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.84.5090 84, 5090 (2000)] have proposed a simple scheme for the evaluation of photoelectron spectra of clusters subject to a laser field by collecting one-particle wave functions at a given measuring point close to absorbing boundaries. The scheme gives reliable results for low and moderate laser fields, but it shows failures for strong laser fields. The formulation relies on the assumption of free-electron propagation close to the boundaries. The laser field, however, can still be active when the first bunches of outgoing electrons reach the measuring point, and therefore the free-particle scenario may not hold anymore in case of high laser intensities. In this paper, hence, we generalize the method by using a model of “free” particles in the presence of an electromagnetic dipole field. Numerical tests show that this generalized scheme reduces to that of Pohl for low and moderate laser intensities, whereas it considerably improves the results of the latter for high intensities, thus extending the applicability of the method.

  13. EPU correction scheme study at the CLS

    SciTech Connect

    Bertwistle, Drew Baribeau, C.; Dallin, L.; Chen, S.; Vogt, J.; Wurtz, W.

    2016-07-27

    The Canadian Light Source (CLS) Quantum Materials Spectroscopy Center (QMSC) beamline will employ a novel double period (55 mm, 180 mm) elliptically polarizing undulator (EPU) to produce photons of arbitrary polarization in the soft X-ray regime. The long period and high field of the 180 mm period EPU will have a strong dynamic focusing effect on the storage ring electron beam. We have considered two partial correction schemes, a 4 m long planar array of BESSY-II style current strips, and soft iron L-shims. In this paper we briefly consider the implementation of these correction schemes.

  14. Security problem on arbitrated quantum signature schemes

    SciTech Connect

    Choi, Jeong Woon; Chang, Ku-Young; Hong, Dowon

    2011-12-15

    Many arbitrated quantum signature schemes implemented with the help of a trusted third party have been developed up to now. In order to guarantee unconditional security, most of them take advantage of the optimal quantum one-time encryption based on Pauli operators. However, in this paper we point out that the previous schemes provide security only against a total break attack and show in fact that there exists an existential forgery attack that can validly modify the transmitted pair of message and signature. In addition, we also provide a simple method to recover security against the proposed attack.

  15. A New Secure Quantum Key Expansion Scheme

    NASA Astrophysics Data System (ADS)

    Yang, Yun-yan; Luo, Lai-zhen; Yin, Gui-sheng

    2013-06-01

    A new quantum key expansion scheme is proposed. The protocol of quantum key expansion proposed by Hwang is analyzed and the eavesdropping scheme is presented. We found that the using of the basis sequence shared by communicating parties is the weakness of the protocol. Hence we propose a `purification attack' for the eavesdropper to steal partial information of the raw key and the new key between communicating parties. In view of this defect, we propose a new protocol of quantum key expansion, where the shared key is encrypted into a sequence of unitary operators which can be used securely against the presented attack.

  16. An Elaborate Secure Quantum Voting Scheme

    NASA Astrophysics Data System (ADS)

    Zhang, Jia-Lei; Xie, Shu-Cui; Zhang, Jian-Zhong

    2017-07-01

    An elaborate secure quantum voting scheme is presented in this paper. It is based on quantum proxy blind signature. The eligible voter's voting information can be transmitted to the tallyman Bob with the help of the scrutineer Charlie. Charlie's supervision in the whole voting process can make the protocol satisfy fairness and un-repeatability so as to avoid Bob's dishonest behaviour. Our scheme uses the physical characteristics of quantum mechanics to achieve voting, counting and immediate supervision. In addition, the program also uses quantum key distribution protocol and quantum one-time pad to guarantee its unconditional security.

  17. ARQ scheme reinforced with past acknowledgement signals

    NASA Astrophysics Data System (ADS)

    Nakamura, Makoto; Takada, Yasushi

    An ARQ (automatic-repeat-request) scheme that can reduce the influence of backward channel errors for bidirectional data transmission systems is proposed. The main feature of the scheme is that both present and past acknowledgement signals are utilized to decide whether the data signals should be retransmitted or not. Throughput performance is analyzed in both go-back-N and selective-repeat ARQ. A small number of returned past acknowledgement signals are required to improve the throughput efficiency. For an ideal selective-repeat ARQ with an infinite buffer, increasing the number of returned past acknowledgement signals makes the throughput efficiency asymptotically close to the upper bound.

  18. A COMPLETE SCHEME FOR A MUON COLLIDER.

    SciTech Connect

    PALMER,R.B.; BERG, J.S.; FERNOW, R.C.; GALLARDO, J.C.; KIRK, H.G.; ALEXAHIN, Y.; NEUFFER, D.; KAHN, S.A.; SUMMERS, D.

    2007-09-01

    A complete scheme for production, cooling, acceleration, and ring for a 1.5 TeV center of mass muon collider is presented, together with parameters for two higher energy machines. The schemes starts with the front end of a proposed neutrino factory that yields bunch trains of both muon signs. Six dimensional cooling in long-period helical lattices reduces the longitudinal emittance until it becomes possible to merge the trains into single bunches, one of each sign. Further cooling in all dimensions is applied to the single bunches in further helical lattices. Final transverse cooling to the required parameters is achieved in 50 T solenoids.

  19. High resolution schemes and the entropy condition

    NASA Technical Reports Server (NTRS)

    Osher, S.; Chakravarthy, S.

    1983-01-01

    A systematic procedure for constructing semidiscrete, second order accurate, variation diminishing, five point band width, approximations to scalar conservation laws, is presented. These schemes are constructed to also satisfy a single discrete entropy inequality. Thus, in the convex flux case, convergence is proven to be the unique physically correct solution. For hyperbolic systems of conservation laws, this construction is used formally to extend the first author's first order accurate scheme, and show (under some minor technical hypotheses) that limit solutions satisfy an entropy inequality. Results concerning discrete shocks, a maximum principle, and maximal order of accuracy are obtained. Numerical applications are also presented.

  20. An Elaborate Secure Quantum Voting Scheme

    NASA Astrophysics Data System (ADS)

    Zhang, Jia-Lei; Xie, Shu-Cui; Zhang, Jian-Zhong

    2017-10-01

    An elaborate secure quantum voting scheme is presented in this paper. It is based on quantum proxy blind signature. The eligible voter's voting information can be transmitted to the tallyman Bob with the help of the scrutineer Charlie. Charlie's supervision in the whole voting process can make the protocol satisfy fairness and un-repeatability so as to avoid Bob's dishonest behaviour. Our scheme uses the physical characteristics of quantum mechanics to achieve voting, counting and immediate supervision. In addition, the program also uses quantum key distribution protocol and quantum one-time pad to guarantee its unconditional security.

  1. Fixed Wordsize Implementation of Lifting Schemes

    NASA Astrophysics Data System (ADS)

    Karp, Tanja

    2006-12-01

    We present a reversible nonlinear discrete wavelet transform with predefined fixed wordsize based on lifting schemes. Restricting the dynamic range of the wavelet domain coefficients due to a fixed wordsize may result in overflow. We show how this overflow has to be handled in order to maintain reversibility of the transform. We also perform an analysis on how large a wordsize of the wavelet coefficients is needed to perform optimal lossless and lossy compressions of images. The scheme is advantageous to well-known integer-to-integer transforms since the wordsize of adders and multipliers can be predefined and does not increase steadily. This also results in significant gains in hardware implementations.

  2. A Trade-off Traitor Tracing Scheme

    NASA Astrophysics Data System (ADS)

    Ohtake, Go; Ogawa, Kazuto; Hanaoka, Goichiro; Imai, Hideki

    There has been a wide-ranging discussion on the issue of content copyright protection in digital content distribution systems. Fiat and Tassa proposed the framework of dynamic traitor tracing. Their framework requires dynamic computation transactions according to the real-time responses of the pirate, and it presumes real-time observation of content redistribution. Therefore, it cannot be simply utilized in an application where such an assumption is not valid. In this paper, we propose a new scheme that provides the advantages of dynamic traitor tracing schemes and also overcomes their problems.

  3. How the Pharmaceutical Benefits Scheme began.

    PubMed

    Goddard, Martyn S

    2014-07-07

    Seventy years ago, the Curtin wartime government introduced legislation for a Pharmaceutical Benefits Scheme (PBS). It was a response to the need to provide access to a wave of antibiotic drugs - sulfonamides, streptomycin, penicillin - to the whole population, not only to the minority able to afford them. The scheme was immediately and successfully opposed by doctors and the conservative opposition, which saw in universal health care an underhand plan to nationalise medicine. There were two High Court challenges, two referendums and a constitutional amendment; but it was not until 1960 that Australians had the comprehensive PBS envisaged by Curtin in 1944.

  4. Student Loans Schemes in Mauritius: Experience, Analysis and Scenarios

    ERIC Educational Resources Information Center

    Mohadeb, Praveen

    2006-01-01

    This study makes a comprehensive review of the situation of student loans schemes in Mauritius, and makes recommendations, based on best practices, for setting up a national scheme that attempts to avoid weaknesses identified in some of the loans schemes of other countries. It suggests that such a scheme would be cost-effective and beneficial both…

  5. A Hash Based Remote User Authentication and Authenticated Key Agreement Scheme for the Integrated EPR Information System.

    PubMed

    Li, Chun-Ta; Weng, Chi-Yao; Lee, Cheng-Chi; Wang, Chun-Cheng

    2015-11-01

    To protect patient privacy and ensure authorized access to remote medical services, many remote user authentication schemes for the integrated electronic patient record (EPR) information system have been proposed in the literature. In a recent paper, Das proposed a hash based remote user authentication scheme using passwords and smart cards for the integrated EPR information system, and claimed that the proposed scheme could resist various passive and active attacks. However, in this paper, we found that Das's authentication scheme is still vulnerable to modification and user duplication attacks. Thereafter we propose a secure and efficient authentication scheme for the integrated EPR information system based on lightweight hash function and bitwise exclusive-or (XOR) operations. The security proof and performance analysis show our new scheme is well-suited to adoption in remote medical healthcare services.

  6. Seasonal activity and morphological changes in martian gullies

    USGS Publications Warehouse

    Dundas, Colin M.; Diniega, Serina; Hansen, Candice J.; Byrne, Shane; McEwen, Alfred S.

    2012-01-01

    Recent studies of martian dune and non-dune gullies have suggested a seasonal control on present-day gully activity. The timing of current gully activity, especially activity involving the formation or modification of channels (which commonly have been taken as evidence of fluvial processes), has important implications regarding likely gully formation processes and necessary environmental conditions. In this study, we describe the results of frequent meter-scale monitoring of several active gully sites by the High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO). The aim is to better assess the scope and nature of current morphological changes and to provide improved constraints on timing of gully activity on both dune and non-dune slopes. Our observations indicate that (1) gully formation on Mars is ongoing today and (2) the most significant morphological changes are strongly associated with seasonal frost and defrosting activity. Observed changes include formation of all major components of typical gully landforms, although we have not observed alcove formation in coherent bedrock. These results reduce the need to invoke recent climate change or present-day groundwater seepage to explain the many martian gullies with pristine appearance.

  7. Implementation of a Cross-Layer Sensing Medium-Access Control Scheme.

    PubMed

    Su, Yishan; Fu, Xiaomei; Han, Guangyao; Xu, Naishen; Jin, Zhigang

    2017-04-10

    In this paper, compressed sensing (CS) theory is utilized in a medium-access control (MAC) scheme for wireless sensor networks (WSNs). We propose a new, cross-layer compressed sensing medium-access control (CL CS-MAC) scheme, combining the physical layer and data link layer, where the wireless transmission in physical layer is considered as a compress process of requested packets in a data link layer according to compressed sensing (CS) theory. We first introduced using compressive complex requests to identify the exact active sensor nodes, which makes the scheme more efficient. Moreover, because the reconstruction process is executed in a complex field of a physical layer, where no bit and frame synchronizations are needed, the asynchronous and random requests scheme can be implemented without synchronization payload. We set up a testbed based on software-defined radio (SDR) to implement the proposed CL CS-MAC scheme practically and to demonstrate the validation. For large-scale WSNs, the simulation results show that the proposed CL CS-MAC scheme provides higher throughput and robustness than the carrier sense multiple access (CSMA) and compressed sensing medium-access control (CS-MAC) schemes.

  8. A target coverage scheduling scheme based on genetic algorithms in directional sensor networks.

    PubMed

    Gil, Joon-Min; Han, Youn-Hee

    2011-01-01

    As a promising tool for monitoring the physical world, directional sensor networks (DSNs) consisting of a large number of directional sensors are attracting increasing attention. As directional sensors in DSNs have limited battery power and restricted angles of sensing range, maximizing the network lifetime while monitoring all the targets in a given area remains a challenge. A major technique to conserve the energy of directional sensors is to use a node wake-up scheduling protocol by which some sensors remain active to provide sensing services, while the others are inactive to conserve their energy. In this paper, we first address a Maximum Set Covers for DSNs (MSCD) problem, which is known to be NP-complete, and present a greedy algorithm-based target coverage scheduling scheme that can solve this problem by heuristics. This scheme is used as a baseline for comparison. We then propose a target coverage scheduling scheme based on a genetic algorithm that can find the optimal cover sets to extend the network lifetime while monitoring all targets by the evolutionary global search technique. To verify and evaluate these schemes, we conducted simulations and showed that the schemes can contribute to extending the network lifetime. Simulation results indicated that the genetic algorithm-based scheduling scheme had better performance than the greedy algorithm-based scheme in terms of maximizing network lifetime.

  9. Central difference TVD and TVB schemes for time dependent and steady state problems

    NASA Technical Reports Server (NTRS)

    Jorgenson, P.; Turkel, E.

    1992-01-01

    We use central differences to solve the time dependent Euler equations. The schemes are all advanced using a Runge-Kutta formula in time. Near shocks, a second difference is added as an artificial viscosity. This reduces the scheme to a first order upwind scheme at shocks. The switch that is used guarantees that the scheme is locally total variation diminishing (TVD). For steady state problems it is usually advantageous to relax this condition. Then small oscillations do not activate the switches and the convergence to a steady state is improved. To sharpen the shocks, different coefficients are needed for different equations and so a matrix valued dissipation is introduced and compared with the scalar viscosity. The connection between this artificial viscosity and flux limiters is shown. Any flux limiter can be used as the basis of a shock detector for an artificial viscosity. We compare the use of the van Leer, van Albada, mimmod, superbee, and the 'average' flux limiters for this central difference scheme. For time dependent problems, we need to use a small enough time step so that the CFL was less than one even though the scheme was linearly stable for larger time steps. Using a total variation bounded (TVB) Runge-Kutta scheme yields minor improvements in the accuracy.

  10. Strong authentication scheme for telecare medicine information systems.

    PubMed

    Pu, Qiong; Wang, Jian; Zhao, Rongyong

    2012-08-01

    The telecare medicine information system enables or supports health-care delivery services. A secure authentication scheme will thus be needed to safeguard data integrity, confidentiality, and availability. In this paper, we propose a generic construction of smart-card-based password authentication protocol and prove its security. The proposed framework is superior to previous schemes in three following aspects : (1) our scheme is a true two-factor authentication scheme. (2) our scheme can yield a forward secure two-factor authentication scheme with user anonymity when appropriately instantiated. (3) our scheme utilizes each user's unique identity to accomplish the user authentication and does not need to store or verify others's certificates. And yet, our scheme is still reasonably efficient and can yield such a concrete scheme that is even more efficient than previous schemes. Therefore the end result is more practical for the telecare medicine system.

  11. Cross-ontological analytics for alignment of different classification schemes

    DOEpatents

    Posse, Christian; Sanfilippo, Antonio P; Gopalan, Banu; Riensche, Roderick M; Baddeley, Robert L

    2010-09-28

    Quantification of the similarity between nodes in multiple electronic classification schemes is provided by automatically identifying relationships and similarities between nodes within and across the electronic classification schemes. Quantifying the similarity between a first node in a first electronic classification scheme and a second node in a second electronic classification scheme involves finding a third node in the first electronic classification scheme, wherein a first product value of an inter-scheme similarity value between the second and third nodes and an intra-scheme similarity value between the first and third nodes is a maximum. A fourth node in the second electronic classification scheme can be found, wherein a second product value of an inter-scheme similarity value between the first and fourth nodes and an intra-scheme similarity value between the second and fourth nodes is a maximum. The maximum between the first and second product values represents a measure of similarity between the first and second nodes.

  12. The Partners in Flight species prioritization scheme

    Treesearch

    William C. Hunter; Michael F. Carter; David N. Pashley; Keith Barker

    1993-01-01

    The prioritization scheme identifies those birds at any locality on several geographic scales most in need of conservation action. Further, it suggests some of those actions that ought to be taken. Ranking criteria used to set priorities for Neotropical migratory landbirds measure characteristics of species that make them vulnerable to local and global extinction....

  13. A new scheme of force reflecting control

    NASA Technical Reports Server (NTRS)

    Kim, Won S.

    1992-01-01

    A new scheme of force reflecting control has been developed that incorporates position-error-based force reflection and robot compliance control. The operator is provided with a kinesthetic force feedback which is proportional to the position error between the operator-commanded and the actual position of the robot arm. Robot compliance control, which increases the effective compliance of the robot, is implemented by low pass filtering the outputs of the force/torque sensor mounted on the base of robot hand and using these signals to alter the operator's position command. This position-error-based force reflection scheme combined with shared compliance control has been implemented successfully to the Advanced Teleoperation system consisting of dissimilar master-slave arms. Stability measurements have demonstrated unprecedentedly high force reflection gains of up to 2 or 3, even though the slave arm is much stiffer than operator's hand holding the force reflecting hand controller. Peg-in-hole experiments were performed with eight different operating modes to evaluate the new force-reflecting control scheme. Best task performance resulted with this new control scheme.

  14. Harmonic generation with multiple wiggler schemes

    SciTech Connect

    Bonifacio, R.; De Salvo, L.; Pierini, P.

    1995-02-01

    In this paper the authors give a simple theoretical description of the basic physics of the single pass high gain free electron laser (FEL), describing in some detail the FEL bunching properties and the harmonic generation technique with a multiple-wiggler scheme or a high gain optical klystron configuration.

  15. A classification scheme for LWR fuel assemblies

    SciTech Connect

    Moore, R.S.; Williamson, D.A.; Notz, K.J.

    1988-11-01

    With over 100 light water nuclear reactors operating nationwide, representing designs by four primary vendors, and with reload fuel manufactured by these vendors and additional suppliers, a wide variety of fuel assembly types are in existence. At Oak Ridge National Laboratory, both the Systems Integration Program and the Characteristics Data Base project required a classification scheme for these fuels. This scheme can be applied to other areas and is expected to be of value to many Office of Civilian Radioactive Waste Management programs. To develop the classification scheme, extensive information on the fuel assemblies that have been and are being manufactured by the various nuclear fuel vendors was compiled, reviewed, and evaluated. It was determined that it is possible to characterize assemblies in a systematic manner, using a combination of physical factors. A two-stage scheme was developed consisting of 79 assembly types, which are grouped into 22 assembly classes. The assembly classes are determined by the general design of the reactor cores in which the assemblies are, or were, used. The general BWR and PWR classes are divided differently but both are based on reactor core configuration. 2 refs., 15 tabs.

  16. A Simplified Scheme for Kinematic Source Inversion

    NASA Astrophysics Data System (ADS)

    Iglesias, A.; Castro-Artola, O.; Singh, S.; Hjorleifsdottir, V.; Legrand, D.

    2013-05-01

    It is well known that different kinematic source inversion schemes lead to non-unique solutions. For this reason, a simplified scheme, which yields the main characteristics of the rupture process, rather than the details, may be desirable. In this work we propose a modification of the frequency-domain inversion scheme of Cotton & Campillo (1995) to extract kinematic parameters using simplified geometries (ellipses). The forward problem is re-parameterized by including one or two ellipses in which the displacement is smoothly distributed. For the ellipses we invert for the position of the centers within the fault plane, the major and minor semi-axes, the maximum displacements, the angles of rotation and a parameter that controls the distribution of slip. A simulated annealing scheme is used to invert near-source displacements. We first test the method on synthetic displacement records corresponding to the Guerrero-Oaxaca earthquake (20/03/2012, Mw=7.5) by comparing the results obtained from the modified technique with the original method. In the next step, we use displacements obtained by double numerical integration of recorded accelerograms. We find that, in spite of the simple geometry, the modified method leads to a good fit between observed and synthetic displacements and recovers the main rupture characteristics.

  17. High Order Semi-Lagrangian Advection Scheme

    NASA Astrophysics Data System (ADS)

    Malaga, Carlos; Mandujano, Francisco; Becerra, Julian

    2014-11-01

    In most fluid phenomena, advection plays an important roll. A numerical scheme capable of making quantitative predictions and simulations must compute correctly the advection terms appearing in the equations governing fluid flow. Here we present a high order forward semi-Lagrangian numerical scheme specifically tailored to compute material derivatives. The scheme relies on the geometrical interpretation of material derivatives to compute the time evolution of fields on grids that deform with the material fluid domain, an interpolating procedure of arbitrary order that preserves the moments of the interpolated distributions, and a nonlinear mapping strategy to perform interpolations between undeformed and deformed grids. Additionally, a discontinuity criterion was implemented to deal with discontinuous fields and shocks. Tests of pure advection, shock formation and nonlinear phenomena are presented to show performance and convergence of the scheme. The high computational cost is considerably reduced when implemented on massively parallel architectures found in graphic cards. The authors acknowledge funding from Fondo Sectorial CONACYT-SENER Grant Number 42536 (DGAJ-SPI-34-170412-217).

  18. Creating Culturally Sustainable Agri-Environmental Schemes

    ERIC Educational Resources Information Center

    Burton, Rob J. F.; Paragahawewa, Upananda Herath

    2011-01-01

    Evidence is emerging from across Europe that contemporary agri-environmental schemes are having only limited, if any, influence on farmers' long-term attitudes towards the environment. In this theoretical paper we argue that these approaches are not "culturally sustainable," i.e. the actions are not becoming embedded within farming…

  19. Tunneling and the Emergent Universe Scheme

    NASA Astrophysics Data System (ADS)

    Labraña, Pedro

    We present an alternative scheme for an Emergent Universe scenario, developed previously in Phys. Rev. D 86, 083524 (2012), where the universe is initially in a static state supported by a scalar field located in a false vacuum. The universe begins to evolve when, by quantum tunneling, the scalar field decays into a state of true vacuum.

  20. Scheme for air treatment in welding workshop

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Wu, Jin

    2017-04-01

    There are two major ways to control the pollution of welding fume which are respectively local purification and comprehensive purification. In this paper, the practical welding workshop at school is taken as an example to realize fume treatment in different training conditions by adopting the scheme in which two major ways are combined.

  1. The MEI Structured Sixth Form Mathematics Scheme.

    ERIC Educational Resources Information Center

    Porkess, Roger

    1991-01-01

    Describes the history and the rationale behind the Structured Sixth Form Scheme, the national secondary school mathematics education program in England, generated by the Mathematics in Education and Industry (MEI) School Project. Discusses the grading system, the implementation schedule, and the advantages of this program that was approved in June…

  2. Fitting coding scheme for image wavelet representation

    NASA Astrophysics Data System (ADS)

    Przelaskowski, Artur

    1998-10-01

    Efficient coding scheme for image wavelet representation in lossy compression scheme is presented. Spatial-frequency hierarchical structure of quantized coefficient and their statistics is analyzed to reduce any redundancy. We applied context-based linear magnitude predictor to fit 1st order conditional probability model in arithmetic coding of significant coefficients to local data characteristics and eliminate spatial and inter-scale dependencies. Sign information is also encoded by inter and intra-band prediction and entropy coding of prediction errors. But main feature of our algorithm deals with encoding way of zerotree structures. Additional symbol of zerotree root is included into magnitude data stream. Moreover, four neighbor zerotree roots with significant parent node are included in extended high-order context model of zerotrees. This significant parent is signed as significant zerotree root and information about these roots distribution is coded separately. The efficiency of presented coding scheme was tested in dyadic wavelet decomposition scheme with two quantization procedures. Simple scalar uniform quantizer and more complex space-frequency quantizer with adaptive data thresholding were used. The final results seem to be promising and competitive across the most effective wavelet compression methods.

  3. Experimental Evaluation of LIDAR Data Visualization Schemes

    NASA Astrophysics Data System (ADS)

    Ghosh, S.; Lohan, B.

    2012-07-01

    LiDAR (Light Detection and Ranging) has attained the status of an industry standard method of data collection for gathering three dimensional topographic information. Datasets captured through LiDAR are dense, redundant and are perceivable from multiple directions, which is unlike other geospatial datasets collected through conventional methods. This three dimensional information has triggered an interest in the scientific community to develop methods for visualizing LiDAR datasets and value added products. Elementary schemes of visualization use point clouds with intensity or colour, triangulation and tetrahedralization based terrain models draped with texture. Newer methods use feature extraction either through the process of classification or segmentation. In this paper, the authors have conducted a visualization experience survey where 60 participants respond to a questionnaire. The questionnaire poses six different questions on the qualities of feature perception and depth for 12 visualization schemes. The answers to these questions are obtained on a scale of 1 to 10. Results are thus presented using the non-parametric Friedman's test, using post-hoc analysis for hypothetically ranking the visualization schemes based on the rating received and finally confirming the rankings through the Page's trend test. Results show that a heuristic based visualization scheme, which has been developed by Ghosh and Lohani (2011) performs the best in terms of feature and depth perception.

  4. Creating Culturally Sustainable Agri-Environmental Schemes

    ERIC Educational Resources Information Center

    Burton, Rob J. F.; Paragahawewa, Upananda Herath

    2011-01-01

    Evidence is emerging from across Europe that contemporary agri-environmental schemes are having only limited, if any, influence on farmers' long-term attitudes towards the environment. In this theoretical paper we argue that these approaches are not "culturally sustainable," i.e. the actions are not becoming embedded within farming…

  5. Configuration-Control Scheme Copes With Singularities

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun; Colbaugh, Richard D.

    1993-01-01

    Improved configuration-control scheme for robotic manipulator having redundant degrees of freedom suppresses large joint velocities near singularities, at expense of small trajectory errors. Provides means to enforce order of priority of tasks assigned to robot. Basic concept of configuration control of redundant robot described in "Increasing The Dexterity Of Redundant Robots" (NPO-17801).

  6. How Can Conceptual Schemes Change Teaching?

    ERIC Educational Resources Information Center

    Wickman, Per-Olof

    2012-01-01

    Lundqvist, Almqvist and Ostman describe a teacher's manner of teaching and the possible consequences it may have for students' meaning making. In doing this the article examines a teacher's classroom practice by systematizing the teacher's transactions with the students in terms of certain conceptual schemes, namely the "epistemological moves",…

  7. A secure and efficient uniqueness-and-anonymity-preserving remote user authentication scheme for connected health care.

    PubMed

    Das, Ashok Kumar; Goswami, Adrijit

    2013-06-01

    Connected health care has several applications including telecare medicine information system, personally controlled health records system, and patient monitoring. In such applications, user authentication can ensure the legality of patients. In user authentication for such applications, only the legal user/patient himself/herself is allowed to access the remote server, and no one can trace him/her according to transmitted data. Chang et al. proposed a uniqueness-and-anonymity-preserving remote user authentication scheme for connected health care (Chang et al., J Med Syst 37:9902, 2013). Their scheme uses the user's personal biometrics along with his/her password with the help of the smart card. The user's biometrics is verified using BioHashing. Their scheme is efficient due to usage of one-way hash function and exclusive-or (XOR) operations. In this paper, we show that though their scheme is very efficient, their scheme has several security weaknesses such as (1) it has design flaws in login and authentication phases, (2) it has design flaws in password change phase, (3) it fails to protect privileged insider attack, (4) it fails to protect the man-in-the middle attack, and (5) it fails to provide proper authentication. In order to remedy these security weaknesses in Chang et al.'s scheme, we propose an improvement of their scheme while retaining the original merit of their scheme. We show that our scheme is efficient as compared to Chang et al.'s scheme. Through the security analysis, we show that our scheme is secure against possible attacks. Further, we simulate our scheme for the formal security verification using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool to ensure that our scheme is secure against passive and active attacks. In addition, after successful authentication between the user and the server, they establish a secret session key shared between them for future secure communication.

  8. Quantum Walk Schemes for Universal Quantum Computation

    NASA Astrophysics Data System (ADS)

    Underwood, Michael S.

    Random walks are a powerful tool for the efficient implementation of algorithms in classical computation. Their quantum-mechanical analogues, called quantum walks, hold similar promise. Quantum walks provide a model of quantum computation that has recently been shown to be equivalent in power to the standard circuit model. As in the classical case, quantum walks take place on graphs and can undergo discrete or continuous evolution, though quantum evolution is unitary and therefore deterministic until a measurement is made. This thesis considers the usefulness of continuous-time quantum walks to quantum computation from the perspectives of both their fundamental power under various formulations, and their applicability in practical experiments. In one extant scheme, logical gates are effected by scattering processes. The results of an exhaustive search for single-qubit operations in this model are presented. It is shown that the number of distinct operations increases exponentially with the number of vertices in the scattering graph. A catalogue of all graphs on up to nine vertices that implement single-qubit unitaries at a specific set of momenta is included in an appendix. I develop a novel scheme for universal quantum computation called the discontinuous quantum walk, in which a continuous-time quantum walker takes discrete steps of evolution via perfect quantum state transfer through small 'widget' graphs. The discontinuous quantum-walk scheme requires an exponentially sized graph, as do prior discrete and continuous schemes. To eliminate the inefficient vertex resource requirement, a computation scheme based on multiple discontinuous walkers is presented. In this model, n interacting walkers inhabiting a graph with 2n vertices can implement an arbitrary quantum computation on an input of length n, an exponential savings over previous universal quantum walk schemes. This is the first quantum walk scheme that allows for the application of quantum error correction

  9. LevelScheme: A level scheme drawing and scientific figure preparation system for Mathematica

    NASA Astrophysics Data System (ADS)

    Caprio, M. A.

    2005-09-01

    LevelScheme is a scientific figure preparation system for Mathematica. The main emphasis is upon the construction of level schemes, or level energy diagrams, as used in nuclear, atomic, molecular, and hadronic physics. LevelScheme also provides a general infrastructure for the preparation of publication-quality figures, including support for multipanel and inset plotting, customizable tick mark generation, and various drawing and labeling tasks. Coupled with Mathematica's plotting functions and powerful programming language, LevelScheme provides a flexible system for the creation of figures combining diagrams, mathematical plots, and data plots. Program summaryTitle of program:LevelScheme Catalogue identifier:ADVZ Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVZ Operating systems:Any which supports Mathematica; tested under Microsoft Windows XP, Macintosh OS X, and Linux Programming language used:Mathematica 4 Number of bytes in distributed program, including test and documentation:3 051 807 Distribution format:tar.gz Nature of problem:Creation of level scheme diagrams. Creation of publication-quality multipart figures incorporating diagrams and plots. Method of solution:A set of Mathematica packages has been developed, providing a library of level scheme drawing objects, tools for figure construction and labeling, and control code for producing the graphics.

  10. Phase II Evaluation of Clinical Coding Schemes

    PubMed Central

    Campbell, James R.; Carpenter, Paul; Sneiderman, Charles; Cohn, Simon; Chute, Christopher G.; Warren, Judith

    1997-01-01

    Abstract Objective: To compare three potential sources of controlled clinical terminology (READ codes version 3.1, SNOMED International, and Unified Medical Language System (UMLS) version 1.6) relative to attributes of completeness, clinical taxonomy, administrative mapping, term definitions and clarity (duplicate coding rate). Methods: The authors assembled 1929 source concept records from a variety of clinical information taken from four medical centers across the United States. The source data included medical as well as ample nursing terminology. The source records were coded in each scheme by an investigator and checked by the coding scheme owner. The codings were then scored by an independent panel of clinicians for acceptability. Codes were checked for definitions provided with the scheme. Codes for a random sample of source records were analyzed by an investigator for “parent” and “child” codes within the scheme. Parent and child pairs were scored by an independent panel of medical informatics specialists for clinical acceptability. Administrative and billing code mapping from the published scheme were reviewed for all coded records and analyzed by independent reviewers for accuracy. The investigator for each scheme exhaustively searched a sample of coded records for duplications. Results: SNOMED was judged to be significantly more complete in coding the source material than the other schemes (SNOMED* 70%; READ 57%; UMLS 50%; *p <.00001). SNOMED also had a richer clinical taxonomy judged by the number of acceptable first-degree relatives per coded concept (SNOMED* 4.56; UMLS 3.17; READ 2.14, *p <.005). Only the UMLS provided any definitions; these were found for 49% of records which had a coding assignment. READ and UMLS had better administrative mappings (composite score: READ* 40.6%; UMLS* 36.1%; SNOMED 20.7%, *p <. 00001), and SNOMED had substantially more duplications of coding assignments (duplication rate: READ 0%; UMLS 4.2%; SNOMED* 13.9%, *p

  11. High-resolution schemes for hyperbolic conservation laws

    NASA Technical Reports Server (NTRS)

    Harten, A.

    1982-01-01

    A class of new explicit second order accurate finite difference schemes for the computation of weak solutions of hyperbolic conservation laws is presented. These highly nonlinear schemes are obtained by applying a nonoscillatory first order accurae scheme to an appropriately modified flux function. The so derived second order accurate schemes achieve high resolution while preserving the robustness of the original nonoscillatory first order accurate scheme.

  12. Simple Numerical Schemes for the Korteweg-deVries Equation

    SciTech Connect

    C. J. McKinstrie; M. V. Kozlov

    2000-12-01

    Two numerical schemes, which simulate the propagation of dispersive non-linear waves, are described. The first is a split-step Fourier scheme for the Korteweg-de Vries (KdV) equation. The second is a finite-difference scheme for the modified KdV equation. The stability and accuracy of both schemes are discussed. These simple schemes can be used to study a wide variety of physical processes that involve dispersive nonlinear waves.

  13. Finite difference schemes for long-time integration

    NASA Technical Reports Server (NTRS)

    Haras, Zigo; Taasan, Shlomo

    1993-01-01

    Finite difference schemes for the evaluation of first and second derivatives are presented. These second order compact schemes were designed for long-time integration of evolution equations by solving a quadratic constrained minimization problem. The quadratic cost function measures the global truncation error while taking into account the initial data. The resulting schemes are applicable for integration times fourfold, or more, longer than similar previously studied schemes. A similar approach was used to obtain improved integration schemes.

  14. A novel secret image sharing scheme based on chaotic system

    NASA Astrophysics Data System (ADS)

    Li, Li; Abd El-Latif, Ahmed A.; Wang, Chuanjun; Li, Qiong; Niu, Xiamu

    2012-04-01

    In this paper, we propose a new secret image sharing scheme based on chaotic system and Shamir's method. The new scheme protects the shadow images with confidentiality and loss-tolerance simultaneously. In the new scheme, we generate the key sequence based on chaotic system and then encrypt the original image during the sharing phase. Experimental results and analysis of the proposed scheme demonstrate a better performance than other schemes and confirm a high probability to resist brute force attack.

  15. Uplink Access Schemes for LTE-Advanced

    NASA Astrophysics Data System (ADS)

    Liu, Le; Inoue, Takamichi; Koyanagi, Kenji; Kakura, Yoshikazu

    The 3GPP LTE-Advanced has been attracting much attention recently, where the channel bandwidth would be beyond the maximum bandwidth of LTE, 20MHz. In LTE, single carrier-frequency division multiple access (SC-FDMA) was accepted as the uplink access scheme due to its advantage of very low cubic metric (CM). For LTE-A wideband transmission, multicarrier access would be more effective than single carrier access to make use of multi-user diversity and can maintain the physical channel structure of LTE, where the control information is transmitted on the edges of each 20MHz. In this paper, we discuss the access schemes in bandwidth under 20MHz as well as over 20MHz. In the case of bandwidth under 20MHz, we propose the access schemes allowing discontinuous resource allocation to enhance average throughput while maintaining cell-edge user throughput, that is, DFT-spread-OFDM with spectrum division control (SDC) and adaptive selection of SC-FDMA and OFDM (SC+OFDM). The number of discontinuous spectrums is denoted as spectrum division (SD). For DFT-S-OFDM, we define a parameter max SD as the upper limit of SD. We evaluate our proposed schemes in bandwidth under 20MHz and find that SC+OFDM as well as SDC with common max SD or UE-specific max SD can improve average throughput while their cell-edge user throughput can approach that of SC-FDMA. In the case of bandwidth over 20MHz, we consider key factors to decide a feasible access scheme for aggregating several 20MHz-wide bands.

  16. Electricity storage using a thermal storage scheme

    NASA Astrophysics Data System (ADS)

    White, Alexander

    2015-01-01

    The increasing use of renewable energy technologies for electricity generation, many of which have an unpredictably intermittent nature, will inevitably lead to a greater demand for large-scale electricity storage schemes. For example, the expanding fraction of electricity produced by wind turbines will require either backup or storage capacity to cover extended periods of wind lull. This paper describes a recently proposed storage scheme, referred to here as Pumped Thermal Storage (PTS), and which is based on "sensible heat" storage in large thermal reservoirs. During the charging phase, the system effectively operates as a high temperature-ratio heat pump, extracting heat from a cold reservoir and delivering heat to a hot one. In the discharge phase the processes are reversed and it operates as a heat engine. The round-trip efficiency is limited only by process irreversibilities (as opposed to Second Law limitations on the coefficient of performance and the thermal efficiency of the heat pump and heat engine respectively). PTS is currently being developed in both France and England. In both cases, the schemes operate on the Joule-Brayton (gas turbine) cycle, using argon as the working fluid. However, the French scheme proposes the use of turbomachinery for compression and expansion, whereas for that being developed in England reciprocating devices are proposed. The current paper focuses on the impact of the various process irreversibilities on the thermodynamic round-trip efficiency of the scheme. Consideration is given to compression and expansion losses and pressure losses (in pipe-work, valves and thermal reservoirs); heat transfer related irreversibility in the thermal reservoirs is discussed but not included in the analysis. Results are presented demonstrating how the various loss parameters and operating conditions influence the overall performance.

  17. Electricity storage using a thermal storage scheme

    SciTech Connect

    White, Alexander

    2015-01-22

    The increasing use of renewable energy technologies for electricity generation, many of which have an unpredictably intermittent nature, will inevitably lead to a greater demand for large-scale electricity storage schemes. For example, the expanding fraction of electricity produced by wind turbines will require either backup or storage capacity to cover extended periods of wind lull. This paper describes a recently proposed storage scheme, referred to here as Pumped Thermal Storage (PTS), and which is based on “sensible heat” storage in large thermal reservoirs. During the charging phase, the system effectively operates as a high temperature-ratio heat pump, extracting heat from a cold reservoir and delivering heat to a hot one. In the discharge phase the processes are reversed and it operates as a heat engine. The round-trip efficiency is limited only by process irreversibilities (as opposed to Second Law limitations on the coefficient of performance and the thermal efficiency of the heat pump and heat engine respectively). PTS is currently being developed in both France and England. In both cases, the schemes operate on the Joule-Brayton (gas turbine) cycle, using argon as the working fluid. However, the French scheme proposes the use of turbomachinery for compression and expansion, whereas for that being developed in England reciprocating devices are proposed. The current paper focuses on the impact of the various process irreversibilities on the thermodynamic round-trip efficiency of the scheme. Consideration is given to compression and expansion losses and pressure losses (in pipe-work, valves and thermal reservoirs); heat transfer related irreversibility in the thermal reservoirs is discussed but not included in the analysis. Results are presented demonstrating how the various loss parameters and operating conditions influence the overall performance.

  18. Performance of a second-order moments advection scheme in an Ocean General Circulation Model

    NASA Astrophysics Data System (ADS)

    Hofmann, M.; Morales Maqueda, M. A.

    2006-05-01

    The reliability of Ocean General Circulation Models (OGCMs) strongly depends on the quality of their tracer advection schemes. For the sake of simplicity and computing time, tracer advection schemes most commonly used in large-scale OGCMs tend to be low-order schemes, which suffer from spurious numerical diffusion and dispersion that result in distorted solutions. The application of high-order schemes would reduce numerical errors, but at a considerable cost in terms of computing time. An alternative to the use of high-order methods is the implementation of algorithms that take into account the sub-grid distribution of tracers. One such method is the Second-Order Moments (SOM) scheme of Prather (1986), which is more accurate than a fourth-order scheme, but at the time consumption of a second-order algorithm. This article presents results from coarse-resolution, global-ocean simulations with very low explicit diapycnal mixing, in which active and passive tracers were advected with the SOM method. We compare the performance of the method with that of more traditional schemes, namely, the FCT (flux corrected transport) and QUICKer (quadratic upstream interpolation for convective kinematics) schemes. In general, the use of the SOM method significantly improves tracer distributions and transports compared to FCT and QUICKer, thus leading to a better representation of ocean currents, notably boundary currents and frontal systems. While model simulations employing the FCT and QUICKer schemes recreate a global overturning circulation with strong upwelling occurring in low latitudes, the SOM simulations admit a circulation pattern closer to that known as the "reconfigured conveyor belt" (Toggweiler and Samuels, 1993), in which the bulk of the global ocean upwelling occurs in the Southern Ocean.

  19. China's Rural Cooperative Medical Scheme: a type of health insurance or a type of health cooperative?

    PubMed

    Wang, Fang; Liang, Yuan

    2017-03-01

    The Cooperative Medical Scheme (CMS) was popular in rural China in the 1960s and 1970s, having garnered praise from the World Bank and World Health Organization as an unprecedented example of a successful health care model in a low-income developing country. However, the CMS almost collapsed in the 1980s. Based on its historical origins and main activities, we think the CMS functioned as a health cooperative rather than a health insurance scheme. Perhaps, however, the importance to the CMS of cooperation between institutions has been overestimated. Overlooked, yet equally important, has been the cooperation between health workers and farmers to target health-related risk factors associated with agricultural work and ways of life. The 'cooperative' character of the CMS includes two aspects: cooperative institutions and cooperative behaviour. Although the CMS collapsed in China, similar schemes are flourishing elsewhere in the world. In the future, in-depth analysis of these schemes is required.

  20. Z‐Scheme Photocatalytic Systems for Promoting Photocatalytic Performance: Recent Progress and Future Challenges

    PubMed Central

    Li, Haijin; Tu, Wenguang

    2016-01-01

    Semiconductor photocatalysts have attracted increased attention due to their great potential for solving energy and environmental problems. The formation of Z‐scheme photocatalytic systems that mimic natural photosynthesis is a promising strategy to improve photocatalytic activity that is superior to single component photocatalysts. The connection between photosystem I (PS I) and photosystem II (PS II) are crucial for constructing efficient Z‐scheme photocatalytic systems using two photocatalysts (PS I and PS II). The present review concisely summarizes and highlights recent state‐of‐the‐art accomplishments of Z‐scheme photocatalytic systems with diverse connection modes, including i) with shuttle redox mediators, ii) without electron mediators, and iii) with solid‐state electron mediators, which effectively increase visible‐light absorption, promote the separation and transportation of photoinduced charge carriers, and thus enhance the photocatalytic efficiency. The challenges and prospects for future development of Z‐scheme photocatalytic systems are also presented. PMID:27980982

  1. Scheme for Quantum Computing Immune to Decoherence

    NASA Technical Reports Server (NTRS)

    Williams, Colin; Vatan, Farrokh

    2008-01-01

    A constructive scheme has been devised to enable mapping of any quantum computation into a spintronic circuit in which the computation is encoded in a basis that is, in principle, immune to quantum decoherence. The scheme is implemented by an algorithm that utilizes multiple physical spins to encode each logical bit in such a way that collective errors affecting all the physical spins do not disturb the logical bit. The scheme is expected to be of use to experimenters working on spintronic implementations of quantum logic. Spintronic computing devices use quantum-mechanical spins (typically, electron spins) to encode logical bits. Bits thus encoded (denoted qubits) are potentially susceptible to errors caused by noise and decoherence. The traditional model of quantum computation is based partly on the assumption that each qubit is implemented by use of a single two-state quantum system, such as an electron or other spin-1.2 particle. It can be surprisingly difficult to achieve certain gate operations . most notably, those of arbitrary 1-qubit gates . in spintronic hardware according to this model. However, ironically, certain 2-qubit interactions (in particular, spin-spin exchange interactions) can be achieved relatively easily in spintronic hardware. Therefore, it would be fortunate if it were possible to implement any 1-qubit gate by use of a spin-spin exchange interaction. While such a direct representation is not possible, it is possible to achieve an arbitrary 1-qubit gate indirectly by means of a sequence of four spin-spin exchange interactions, which could be implemented by use of four exchange gates. Accordingly, the present scheme provides for mapping any 1-qubit gate in the logical basis into an equivalent sequence of at most four spin-spin exchange interactions in the physical (encoded) basis. The complexity of the mathematical derivation of the scheme from basic quantum principles precludes a description within this article; it must suffice to report

  2. Effect of some factors used to the chicken meat preservation and processing on the protease activity.

    PubMed

    Przysiezna, E; Skrabka-Blotnicka, T

    1996-08-01

    The obtained results indicated that the cathepsin activity was higher by about 60% in the extract from thigh than from breast muscles. Freezing and defrosting (not stored) of chicken meat did not influence the breast muscle cathepsin activity while they caused a decrease of activity of about 20% in the case of thigh muscles. The increase in cathepsin activity was noticed in both kinds of muscles during storage at -20 degrees C up to 4 months (45.6% and 19.4% for thigh and breast muscles respectively). The activity of cathepsin in extract from 5 months stored meat reached 80% in case of breast muscles and 83% in case of thigh muscles in relation to control sample respectively. The cathepsin activity significantly increased during heating of breast muscles up to 60 degrees C, but in case of thigh muscles it was slightly higher than at 50 degrees C. The heating of cured chicken breast muscles up to 60 degrees C caused a non significant growth in cathepsin activity opposite to raw muscles. The cathepsin activity from all cured samples heated up to 70 degrees C were several times lower in relation to control samples. The cathepsin activity of both thigh and breast muscles were resistant to gamma radiation. The investigated factors caused changes in the activity of cathepsin but none of them caused its total inactivation. The changes of cathepsin activity depended on the kind of muscles and the kind and the value of acting factors.

  3. How might a statistical cloud scheme be coupled to a mass-flux convection scheme?

    SciTech Connect

    Klein, Stephen A.; Pincus, Robert; Hannay, Cecile; Xu, Kuan-man

    2004-09-27

    The coupling of statistical cloud schemes with mass-flux convection schemes is addressed. Source terms representing the impact of convection are derived within the framework of prognostic equations for the width and asymmetry of the probability distribution function of total water mixing ratio. The accuracy of these source terms is quantified by examining output from a cloud resolving model simulation of deep convection. Practical suggestions for inclusion of these source terms in large-scale models are offered.

  4. An authentication scheme for secure access to healthcare services.

    PubMed

    Khan, Muhammad Khurram; Kumari, Saru

    2013-08-01

    Last few decades have witnessed boom in the development of information and communication technologies. Health-sector has also been benefitted with this advancement. To ensure secure access to healthcare services some user authentication mechanisms have been proposed. In 2012, Wei et al. proposed a user authentication scheme for telecare medical information system (TMIS). Recently, Zhu pointed out offline password guessing attack on Wei et al.'s scheme and proposed an improved scheme. In this article, we analyze both of these schemes for their effectiveness in TMIS. We show that Wei et al.'s scheme and its improvement proposed by Zhu fail to achieve some important characteristics necessary for secure user authentication. We find that security problems of Wei et al.'s scheme stick with Zhu's scheme; like undetectable online password guessing attack, inefficacy of password change phase, traceability of user's stolen/lost smart card and denial-of-service threat. We also identify that Wei et al.'s scheme lacks forward secrecy and Zhu's scheme lacks session key between user and healthcare server. We therefore propose an authentication scheme for TMIS with forward secrecy which preserves the confidentiality of air messages even if master secret key of healthcare server is compromised. Our scheme retains advantages of Wei et al.'s scheme and Zhu's scheme, and offers additional security. The security analysis and comparison results show the enhanced suitability of our scheme for TMIS.

  5. New communication schemes based on adaptive synchronization.

    PubMed

    Yu, Wenwu; Cao, Jinde; Wong, Kwok-Wo; Lü, Jinhu

    2007-09-01

    In this paper, adaptive synchronization with unknown parameters is discussed for a unified chaotic system by using the Lyapunov method and the adaptive control approach. Some communication schemes, including chaotic masking, chaotic modulation, and chaotic shift key strategies, are then proposed based on the modified adaptive method. The transmitted signal is masked by chaotic signal or modulated into the system, which effectively blurs the constructed return map and can resist this return map attack. The driving system with unknown parameters and functions is almost completely unknown to the attackers, so it is more secure to apply this method into the communication. Finally, some simulation examples based on the proposed communication schemes and some cryptanalysis works are also given to verify the theoretical analysis in this paper.

  6. Approximate particle spectra in the pyramid scheme

    NASA Astrophysics Data System (ADS)

    Banks, Tom; Torres, T. J.

    2012-12-01

    We construct a minimal model inspired by the general class of pyramid schemes [T. Banks and J.-F. Fortin, J. High Energy Phys. 07 (2009) 046JHEPFG1029-8479], which is consistent with both supersymmetry breaking and electroweak symmetry breaking. In order to do computations, we make unjustified approximations to the low energy Kähler potential. The phenomenological viability of the resultant mass spectrum is then examined and compared with current collider limits. We show that for certain regimes of parameters, the model, and thus generically the pyramid scheme, can accommodate the current collider mass constraints on physics beyond the standard model with a tree-level light Higgs mass near 125 GeV. However, in this regime the model exhibits a little hierarchy problem, and one must permit fine-tunings that are of order 5%.

  7. Multigrid solutions to quasi-elliptic schemes

    NASA Technical Reports Server (NTRS)

    Brandt, A.; Taasan, S.

    1985-01-01

    Quasi-elliptic schemes arise from central differencing or finite element discretization of elliptic systems with odd order derivatives on non-staggered grids. They are somewhat unstable and less accurate then corresponding staggered-grid schemes. When usual multigrid solvers are applied to them, the asymptotic algebraic convergence is necessarily slow. Nevertheless, it is shown by mode analyses and numerical experiments that the usual FMG algorithm is very efficient in solving quasi-elliptic equations to the level of truncation errors. Also, a new type of multigrid algorithm is presented, mode analyzed and tested, for which even the asymptotic algebraic convergence is fast. The essence of that algorithm is applicable to other kinds of problems, including highly indefinite ones.

  8. Signal Processing Schemes for Doppler Global Velocimetry

    NASA Technical Reports Server (NTRS)

    Meyers, James F.; Lee, Joseph W.; Cavone, Angelo A.

    1991-01-01

    Two schemes for processing signals obtained from the Doppler global velocimeter are described. The analog approach is a simple, real time method for obtaining an RS-170 video signal containing the normalized intensity image. Pseudo colors are added using a monochromatic frame grabber producing a standard NTSC video signal that can be monitored and/or recorded. The digital approach is more complicated, but maintains the full resolution of the acquisition cameras with the capabilities to correct the signal image for pixel sensitivity variations and to remove of background light. Prototype circuits for each scheme are described and example results from the investigation of the vortical flow field above a 75-degree delta wing presented.

  9. Trefftz difference schemes on irregular stencils

    SciTech Connect

    Tsukerman, Igor

    2010-04-20

    The recently developed Flexible Local Approximation MEthod (FLAME) produces accurate difference schemes by replacing the usual Taylor expansion with Trefftz functions - local solutions of the underlying differential equation. This paper advances and casts in a general form a significant modification of FLAME proposed recently by Pinheiro and Webb: a least-squares fit instead of the exact match of the approximate solution at the stencil nodes. As a consequence of that, FLAME schemes can now be generated on irregular stencils with the number of nodes substantially greater than the number of approximating functions. The accuracy of the method is preserved but its robustness is improved. For demonstration, the paper presents a number of numerical examples in 2D and 3D: electrostatic (magnetostatic) particle interactions, scattering of electromagnetic (acoustic) waves, and wave propagation in a photonic crystal. The examples explore the role of the grid and stencil size, of the number of approximating functions, and of the irregularity of the stencils.

  10. The Linear Bicharacteristic Scheme for Electromagnetics

    NASA Technical Reports Server (NTRS)

    Beggs, John H.

    2001-01-01

    The upwind leapfrog or Linear Bicharacteristic Scheme (LBS) has previously been implemented and demonstrated on electromagnetic wave propagation problems. This paper extends the Linear Bicharacteristic Scheme for computational electromagnetics to model lossy dielectric and magnetic materials and perfect electrical conductors. This is accomplished by proper implementation of the LBS for homogeneous lossy dielectric and magnetic media and for perfect electrical conductors. Heterogeneous media are modeled through implementation of surface boundary conditions and no special extrapolations or interpolations at dielectric material boundaries are required. Results are presented for one-dimensional model problems on both uniform and nonuniform grids, and the FDTD algorithm is chosen as a convenient reference algorithm for comparison. The results demonstrate that the explicit LBS is a dissipation-free, second-order accurate algorithm which uses a smaller stencil than the FDTD algorithm, yet it has approximately one-third the phase velocity error. The LBS is also more accurate on nonuniform grids.

  11. A multivariable control scheme for robot manipulators

    NASA Technical Reports Server (NTRS)

    Tarokh, M.; Seraji, H.

    1991-01-01

    The article puts forward a simple scheme for multivariable control of robot manipulators to achieve trajectory tracking. The scheme is composed of an inner loop stabilizing controller and an outer loop tracking controller. The inner loop utilizes a multivariable PD controller to stabilize the robot by placing the poles of the linearized robot model at some desired locations. The outer loop employs a multivariable PID controller to achieve input-output decoupling and trajectory tracking. The gains of the PD and PID controllers are related directly to the linearized robot model by simple closed-form expressions. The controller gains are updated on-line to cope with variations in the robot model during gross motion and for payload change. Alternatively, the use of high gain controllers for gross motion and payload change is discussed. Computer simulation results are given for illustration.

  12. CUP-syndrome diagnostic procedure scheme.

    PubMed

    Pujanek, Zuzanna; Burduk, Paweł K

    2013-01-01

    Patients with CUP-Syndrome represent a small percentage of patients treated by ENT doctor. Often, in spite of the implementation detailed diagnostics, detection of the primary tumor fails. Very important element is to follow the correct sequence of tests and taking into account conditions outside ENT. I our article, we would like to propose a diagnostic scheme including interview with patient, laryngological and imaging tests and multi-disciplinary consulting. We hope that this scheme will facilitate the treatment of patients with CUP-Syndrome and increase the efficiency of detection of primary tumor. Copyright © 2013 Polish Otorhinolaryngology - Head and Neck Surgery Society. Published by Elsevier Urban & Partner Sp. z.o.o. All rights reserved.

  13. Improving the accuracy of central difference schemes

    NASA Technical Reports Server (NTRS)

    Turkel, Eli

    1988-01-01

    General difference approximations to the fluid dynamic equations require an artificial viscosity in order to converge to a steady state. This artificial viscosity serves two purposes. One is to suppress high frequency noise which is not damped by the central differences. The second purpose is to introduce an entropy-like condition so that shocks can be captured. These viscosities need a coefficient to measure the amount of viscosity to be added. In the standard scheme, a scalar coefficient is used based on the spectral radius of the Jacobian of the convective flux. However, this can add too much viscosity to the slower waves. Hence, it is suggested that a matrix viscosity be used. This gives an appropriate viscosity for each wave component. With this matrix valued coefficient, the central difference scheme becomes closer to upwind biased methods.

  14. The Scheme of Beam Synchronization in MEIC

    SciTech Connect

    Zhang, Yuhong; Derbenev, Yaroslav S.; Hutton, Andrew M.

    2013-06-01

    Synchronizing colliding beams at single or multiple collision points is a critical R&D issue in the design of a medium energy electron-ion collider (MEIC) at Jefferson Lab. The path-length variation due to changes in the ion energy, which varies over 20 to 100 GeV, could be more than several times the bunch spacing. The scheme adopted in the present MEIC baseline is centered on varying the number of bunches (i.e., harmonic number) stored in the collider ring. This could provide a set of discrete energies for proton or ions such that the beam synchronization condition is satisfied. To cover the ion energy between these synchronized values, we further propose to vary simultaneously the electron ring circumference and the frequency of the RF systems in both collider rings. We also present in this paper the requirement of frequency tunability of SRF cavities to support the scheme.

  15. Iterated upwind schemes for gas dynamics

    NASA Astrophysics Data System (ADS)

    Smolarkiewicz, Piotr K.; Szmelter, Joanna

    2009-01-01

    A class of high-resolution schemes established in integration of anelastic equations is extended to fully compressible flows, and documented for unsteady (and steady) problems through a span of Mach numbers from zero to supersonic. The schemes stem from iterated upwind technology of the multidimensional positive definite advection transport algorithm (MPDATA). The derived algorithms employ standard and modified forms of the equations of gas dynamics for conservation of mass, momentum and either total or internal energy as well as potential temperature. Numerical examples from elementary wave propagation, through computational aerodynamics benchmarks, to atmospheric small- and large-amplitude acoustics with intricate wave-flow interactions verify the approach for both structured and unstructured meshes, and demonstrate its flexibility and robustness.

  16. Multiple Access Schemes for Lunar Missions

    NASA Technical Reports Server (NTRS)

    Deutsch, Leslie; Hamkins, Jon; Stocklin, Frank J.

    2010-01-01

    Two years ago, the NASA Coding, Modulation, and Link Protocol (CMLP) study was completed. The study, led by the authors of this paper, recommended codes, modulation schemes, and desired attributes of link protocols for all space communication links in NASA's future space architecture. Portions of the NASA CMLP team were reassembled to resolve one open issue: the use of multiple access (MA) communication from the lunar surface. The CMLP-MA team analyzed and simulated two candidate multiple access schemes that were identified in the original CMLP study: Code Division MA (CDMA) and Frequency Division MA (FDMA) based on a bandwidth-efficient Continuous Phase Modulation (CPM) with a superimposed Pseudo-Noise (PN) ranging signal (CPM/PN). This paper summarizes the results of the analysis and simulation of the CMLP-MA study and describes the final recommendations.

  17. Multiple Access Schemes for Lunar Missions

    NASA Technical Reports Server (NTRS)

    Deutsch, Leslie; Hamkins, Jon; Stocklin, Frank J.

    2010-01-01

    Two years ago, the NASA Coding, Modulation, and Link Protocol (CMLP) study was completed. The study, led by the authors of this paper, recommended codes, modulation schemes, and desired attributes of link protocols for all space communication links in NASA's future space architecture. Portions of the NASA CMLP team were reassembled to resolve one open issue: the use of multiple access (MA) communication from the lunar surface. The CMLP-MA team analyzed and simulated two candidate multiple access schemes that were identified in the original CMLP study: Code Division MA (CDMA) and Frequency Division MA (FDMA) based on a bandwidth-efficient Continuous Phase Modulation (CPM) with a superimposed Pseudo-Noise (PN) ranging signal (CPM/PN). This paper summarizes the results of the analysis and simulation of the CMLP-MA study and describes the final recommendations.

  18. Automatic-repeat-request error control schemes

    NASA Technical Reports Server (NTRS)

    Lin, S.; Costello, D. J., Jr.; Miller, M. J.

    1983-01-01

    Error detection incorporated with automatic-repeat-request (ARQ) is widely used for error control in data communication systems. This method of error control is simple and provides high system reliability. If a properly chosen code is used for error detection, virtually error-free data transmission can be attained. Various types of ARQ and hybrid ARQ schemes, and error detection using linear block codes are surveyed.

  19. The Emergent Universe scheme and tunneling

    NASA Astrophysics Data System (ADS)

    Labraña, Pedro

    2014-07-01

    We present an alternative scheme for an Emergent Universe scenario, developed previously in Phys. Rev. D 86, 083524 (2012), where the universe is initially in a static state supported by a scalar field located in a false vacuum. The universe begins to evolve when, by quantum tunneling, the scalar field decays into a state of true vacuum. The Emergent Universe models are interesting since they provide specific examples of non-singular inflationary universes.

  20. Development of new flux splitting schemes

    NASA Technical Reports Server (NTRS)

    Liou, MENG-S.; Steffen, Christopher J., Jr.

    1991-01-01

    Maximizing both accuracy and efficiency has been the primary objective in designing a numerical algorithm for CFD. This is especially important for solution of complex three-dimensional systems of Navier-Stokes equations which often include turbulence modeling and chemistry effects. Recently, upwind schemes have been well received for both their capability of resolving discontinuities and their sound theoretical basis in characteristic theory for hyperbolic systems. With this in mind, two new flux splitting techniques are presented for upwind differencing.

  1. Vector Meson Property in Covariant Classification Scheme

    NASA Astrophysics Data System (ADS)

    Oda, Masuho

    2004-08-01

    Recently our collaboration group has proposed the covariant classification shceme of hadrons, leading to possible existence of two ground state vector mesons. One is corresponding to ordinary ρ nonet and the other is extra ρ nonet. We investigate the decay property of ω(1250) and ρ(1250) in the covariant classification scheme. And it is shown that ω(1250) is promising candidate of our extra ω meson.

  2. The Emergent Universe scheme and tunneling

    SciTech Connect

    Labraña, Pedro

    2014-07-23

    We present an alternative scheme for an Emergent Universe scenario, developed previously in Phys. Rev. D 86, 083524 (2012), where the universe is initially in a static state supported by a scalar field located in a false vacuum. The universe begins to evolve when, by quantum tunneling, the scalar field decays into a state of true vacuum. The Emergent Universe models are interesting since they provide specific examples of non-singular inflationary universes.

  3. A continuous buoyancy based convection scheme

    NASA Astrophysics Data System (ADS)

    Guérémy, J.-F.

    2009-04-01

    A new and consistent convection scheme, providing a continuous treatment of this atmospheric process, is described. The main concept ensuring the consistency of the whole system is the buoyancy, key element of any vertical motion. The buoyancy constitutes the forcing term of the convective vertical velocity, which is then used to define the triggering condition, the mass flux, and the rates of entrainment-detrainment. The buoyancy is also used in its vertically integrated form (CAPE) to determine the closure condition. The continuous treatment of convection, from dry thermals to deep precipitating convection, is achieved with the help of a continuous formulation of the entrainment-detrainment rates (depending on the convective vertical velocity) and of the CAPE relaxation time (depending on the convective over-turning time). A Single Column Model (SCM) validation of this scheme is shown, allowing detailed comparisons with observed and explicitly simulated data. Four cases covering the convective spectrum are considered: over ocean, deep convection (TOGA), trade wind shallow convection (BOMEX) and strato-cumulus (FIRE), together with a entire continental diurnal cycle of convection (ARM). The emphasis is put on the characteristics of the scheme which enable a continuous treatment of convection. A General Circulation Model (GCM) 23-year simulation is also presented in order to assess the model climate against the observed one.

  4. Progress on Implementing Additional Physics Schemes into ...

    EPA Pesticide Factsheets

    The U.S. Environmental Protection Agency (USEPA) has a team of scientists developing a next generation air quality modeling system employing the Model for Prediction Across Scales – Atmosphere (MPAS-A) as its meteorological foundation. Several preferred physics schemes and options available in the Weather Research and Forecasting (WRF) model are regularly used by the USEPA with the Community Multiscale Air Quality (CMAQ) model to conduct retrospective air quality simulations. These include the Pleim surface layer, the Pleim-Xiu (PX) land surface model with fractional land use for a 40-class National Land Cover Database (NLCD40), the Asymmetric Convective Model 2 (ACM2) planetary boundary layer scheme, the Kain-Fritsch (KF) convective parameterization with subgrid-scale cloud feedback to the radiation schemes and a scale-aware convective time scale, and analysis nudging four-dimensional data assimilation (FDDA). All of these physics modules and options have already been implemented by the USEPA into MPAS-A v4.0, tested, and evaluated (please see the presentations of R. Gilliam and R. Bullock at this workshop). Since the release of MPAS v5.1 in May 2017, work has been under way to implement these preferred physics options into the MPAS-A v5.1 code. Test simulations of a summer month are being conducted on a global variable resolution mesh with the higher resolution cells centered over the contiguous United States. Driving fields for the FDDA and soil nudging are

  5. Sustainability of effluent irrigation schemes: Measurable definition

    SciTech Connect

    Hu, X.

    1997-09-01

    Traditionally water requirements and nutrient removal capacity by plants are considered as the main design criteria of effluent irrigation schemes. Environmental impacts of schemes on surface and groundwater pollution, which may be controlling factors in some circumstances, have not been considered in the design process. In this paper the implication of the sustainability for effluent irrigation schemes has been identified through investigating the pollutant fate. An index has been developed to measure the sustainability status. A dynamic simulation model of the soil-plant system was used to predict the pollutant export to surface runoff and ground water. Pollutant accumulation in the soil profile was also predicted by the model. The traditional design procedure has been extended using the sustainable index as a design criterion and the simulation model for data generation. The application of sustainable concept and index was demonstrated through a test case. Ground-water pollution was found to be the controlling factor instead of water requirement and nutrient removal capacity in this case.

  6. An Enhanced Secure Authentication Scheme with Anonymity for Wireless Environments

    NASA Astrophysics Data System (ADS)

    Jeon, Woongryul; Kim, Jeeyeon; Nam, Junghyun; Lee, Youngsook; Won, Dongho

    As anonymity increasingly becomes a necessary and legitimate aim in many applications, a number of anonymous authentication schemes have been suggested over the years. Among the many schemes is Lee and Kwon's password-based authentication scheme for wireless environments. Compared with previous schemes, Lee and Kwon's scheme not only improves anonymity by employing random temporary IDs but also provides user-friendliness by allowing human-memorable passwords. In this letter, we point out that Lee and Kwon's scheme, despite its many merits, is vulnerable to off-line password guessing attacks and a forgery attack. In addition, we show how to eliminate these vulnerabilities.

  7. A weak blind signature scheme based on quantum cryptography

    NASA Astrophysics Data System (ADS)

    Wen, Xiaojun; Niu, Xiamu; Ji, Liping; Tian, Yuan

    2009-02-01

    In this paper, we present a weak blind signature scheme based on the correlation of EPR (Einstein-Padolsky-Rosen) pairs. Different from classical blind signature schemes and current quantum signature schemes, our quantum blind signature scheme could guarantee not only the unconditionally security but also the anonymity of the message owner. To achieve that, quantum key distribution and one-time pad are adopted in our scheme. Experimental analysis proved that our scheme have the characteristics of non-counterfeit, non-disavowal, blindness and traceability. It has a wide application to E-payment system, E-government, E-business, and etc.

  8. Efficient hop by hop buffer class flow control schemes

    NASA Astrophysics Data System (ADS)

    Chen, Moo-Song; Kadaba, Bharath; Grover, George

    Design issues of hop-by-hop buffer class flow-control schemes are discussed. They are: (1) good window size for high-speed and large-propagation-delay environments and (2) the concept of congestion and access fairness. Schemes are proposed for buffer classification and window-size adjustment. A novel buffer classification, the path-based scheme, has the same fairness property but fewer classes than the route-based scheme. The window adjustment shceme, the quasistatic scheme, has similar or slightly worse performance to, but requires much less complexity than, dynamic schemes.

  9. An active alignment scheme for the MPTS array

    NASA Astrophysics Data System (ADS)

    Iwasaki, R.

    1980-12-01

    In order to achieve and maintain required flatness of the antenna array, a rotating laser beam used for leveling applications on earth was utilized as a reference system. A photoconductive sensor with a reflective collecting surface determines the displacement and polarity of any misalignment and automatically engages a stepping motor to drive a variable-length mechanism to make the necessary corrections. Once aligned, little power is dissipated since a nulling bridge circuit that centers on the beam is used. A three-point subarray alignment arrangement is described which independently adjusts, in the three orthogonal directions, the height and tilt of subarrays within the MPTS array and readily adapts to any physical distortions of the secondary structure (such as that resulting from severe temperature extremes caused by an eclipse of the Sun). It is shown that only one rotating laser system is required since optical blockage is minimal on the array surface and that it is possible to incorporate a number of redundant laser systems for reliability without affecting the overall performance.

  10. An active alignment scheme for the MPTS array. [contour sensors

    NASA Technical Reports Server (NTRS)

    Iwasaki, R.

    1980-01-01

    In order to achieve and maintain required flatness of the antenna array, a rotating laser beam used for leveling applications on earth was utilized as a reference system. A photoconductive sensor with a reflective collecting surface determines the displacement and polarity of any misalignment and automatically engages a stepping motor to drive a variable-length mechanism to make the necessary corrections. Once aligned, little power is dissipated since a nulling bridge circuit that centers on the beam is used. A three-point subarray alignment arrangement is described which independently adjusts, in the three orthogonal directions, the height and tilt of subarrays within the MPTS array and readily adapts to any physical distortions of the secondary structure (such as that resulting from severe temperature extremes caused by an eclipse of the Sun). It is shown that only one rotating laser system is required since optical blockage is minimal on the array surface and that it is possible to incorporate a number of redundant laser systems for reliability without affecting the overall performance.

  11. An active alignment scheme for the MPTS array

    NASA Technical Reports Server (NTRS)

    Iwasaki, R.

    1980-01-01

    In order to maximize the efficiency of the microwave power transmission system (MPTS), the surface of the array antenna must be extremely flat, which is difficult to achieve using passive techniques over the 1 km dimensions of the array. In order to achieve and maintain this required flatness, a rotating laser beam used for leveling applications on Earth was utilized as a reference system. A photoconductive sensor with a reflective collecting surface was used to determine the displacement and polarity of any misalignment and automatically engage a stepping motor to drive a variable-length mechanism to make the necessary corrections. Once aligned, little power is dissipated since a nulling bridge circuit that centers on the beam is used, an important alignment feature since even laser beams broaden considerably at 1 km distances.

  12. An improved and effective secure password-based authentication and key agreement scheme using smart cards for the telecare medicine information system.

    PubMed

    Das, Ashok Kumar; Bruhadeshwar, Bezawada

    2013-10-01

    Recently Lee and Liu proposed an efficient password based authentication and key agreement scheme using smart card for the telecare medicine information system [J. Med. Syst. (2013) 37:9933]. In this paper, we show that though their scheme is efficient, their scheme still has two security weaknesses such as (1) it has design flaws in authentication phase and (2) it has design flaws in password change phase. In order to withstand these flaws found in Lee-Liu's scheme, we propose an improvement of their scheme. Our improved scheme keeps also the original merits of Lee-Liu's scheme. We show that our scheme is efficient as compared to Lee-Liu's scheme. Further, through the security analysis, we show that our scheme is secure against possible known attacks. In addition, we simulate our scheme for the formal security verification using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool to show that our scheme is secure against passive and active attacks.

  13. Uncertainty of Microphysics Schemes in CRMs

    NASA Astrophysics Data System (ADS)

    Tao, W. K.; van den Heever, S. C.; Wu, D.; Saleeby, S. M.; Lang, S. E.

    2015-12-01

    Microphysics is the framework through which to understand the links between interactive aerosol, cloud and precipitation processes. These processes play a critical role in the water and energy cycle. CRMs with advanced microphysics schemes have been used to study the interaction between aerosol, cloud and precipitation processes at high resolution. But, there are still many uncertainties associated with these microphysics schemes. This has arisen, in part, from the fact microphysical processes cannot be measured directly; instead, cloud properties, which can be measured, are and have been used to validate model results. The utilization of current and future global high-resolution models is rapidly increasing and are at what has been traditional CRM resolutions and are using microphysics schemes that were developed in traditional CRMs. A potential NASA satellite mission called the Cloud and Precipitation Processes Mission (CaPPM) is currently being planned for submission to the NASA Earth Science Decadal Survey. This mission could provide the necessary global estimates of cloud and precipitation properties with which to evaluate and improve dynamical and microphysical parameterizations and the feedbacks. In order to facilitate the development of this mission, CRM simulations have been conducted to identify microphysical processes responsible for the greatest uncertainties in CRMs. In this talk, we will present results from numerical simulations conducted using two CRMs (NU-WRF and RAMS) with different dynamics, radiation, land surface and microphysics schemes. Specifically, we will conduct sensitivity tests to examine the uncertainty of the some of the key ice processes (i.e. riming, melting, freezing and shedding) in these two-microphysics schemes. The idea is to quantify how these two different models' respond (surface rainfall and its intensity, strength of cloud drafts, LWP/IWP, convective-stratiform-anvil area distribution) to changes of these key ice

  14. A modified F/A-18 in a distinctive red, white and blue paint scheme was showcased during formal roll

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A modified F/A-18 in a distinctive red, white and blue paint scheme was showcased during formal rollout ceremonies for the Active Aeroelastic Wing flight research program at NASA's Dryden Flight Research Center on March 27, 2002.

  15. A modified F/A-18 in a distinctive red, white and blue paint scheme was showcased during formal roll

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A modified F/A-18 in a distinctive red, white and blue paint scheme was showcased during formal rollout ceremonies for the Active Aeroelastic Wing flight research program at NASA's Dryden Flight Research Center on March 27, 2002.

  16. Evaluation of the end user (dentist) experience of undertaking clinical audit in a PCT-led NHS Modernisation Agency pilot scheme.

    PubMed

    Cannell, Phillip J

    2009-10-01

    A new dental contract was introduced in the National Health Service (NHS) General Dental Services (GDS) in April 2006. Responsibility for clinical audit activities was devolved to Primary Care Trusts (PCTs) as part of their clinical governance remit. In July 2003, an NHS Modernisation Agency pilot scheme for clinical audit was launched by Southend PCT. The aim of this study was to evaluate this scheme. A qualitative research method was used. It used audiotape recorded semi-structured research interviews with eight general dental practitioners (GDPs) who had taken part in the scheme. The evaluation focused on dentists' experiences of the scheme. Dentists appreciated the central PCT-based coordinator for the scheme and found that the streamlining of design, analysis and report writing within the audit projects enabled efficient use of time. The design by an outside agency appeared to add credibility to the scheme. Participants felt that comparability of data derived from clinical audit was enhanced by the scheme and could lead to comparison across PCT patch, regional or even national levels. The use of feedback mechanisms within the scheme was appreciated and thought to help produce maximum value from a clinical audit project. There was evidence of beneficial change occurring within practices and for patients. This study provided an evaluation of a particular clinical audit scheme, several aspects of which differed from the traditional GDS scheme. Organisations proposing to undertake clinical audit activities in conjunction with dentistry in the future may benefit from incorporating elements of this scheme into their project design.

  17. Location and Pressures Change Prediction of Bromo Volcano Magma Chamber Using Inversion Scheme

    NASA Astrophysics Data System (ADS)

    Kumalasari, Ratih; Srigutomo, Wahyu; Djamal, Mitra

    2017-05-01

    Bromo volcano is one of active volcanoes in Indonesia. It has erupted at least 50 times since 1775 and has been monitored by Global Positioning System (GPS) since 1989. We applied the Levenberg-Marquardt inversion scheme to estimate the physical parameters contributing to the surface deformation. Physical parameters obtained by the inversion scheme such as magma chamber location and volume change are useful in monitoring and predicting the activity of Bromo volcano. From our calculation it is revealed that the depth of the magma chamber d = 6307.6 m, radius of magma chamber α = 1098.6 m and pressure change ΔP ≈ 1.0 MPa.

  18. Location and Pressures Change Prediction of Bromo Volcano Magma Chamber Using Inversion Scheme

    NASA Astrophysics Data System (ADS)

    Kumalasari, Ratih; Srigutomo, Wahyu

    2016-08-01

    Bromo volcano is one of active volcanoes in Indonesia. It has erupted at least 50 times since 1775 and has been monitored by Global Positioning System (GPS) since 1989. We applied the Levenberg-Marquardt inversion scheme to estimate the physical parameters contributing to the surface deformation. Physical parameters obtained by the inversion scheme such as magma chamber location and volume change are useful in monitoring and predicting the activity of Bromo volcano. From our calculation it is revealed that the depth of the magma chamber d = 6307.6 m, radius of magma chamber α = 1098.6 m and pressure change ΔP ≈ 1.0 MPa.

  19. An Energy Efficient Mutual Authentication and Key Agreement Scheme Preserving Anonymity for Wireless Sensor Networks.

    PubMed

    Lu, Yanrong; Li, Lixiang; Peng, Haipeng; Yang, Yixian

    2016-06-08

    WSNs (Wireless sensor networks) are nowadays viewed as a vital portion of the IoTs (Internet of Things). Security is a significant issue in WSNs, especially in resource-constrained environments. AKA (Authentication and key agreement) enhances the security of WSNs against adversaries attempting to get sensitive sensor data. Various AKA schemes have been developed for verifying the legitimate users of a WSN. Firstly, we scrutinize Amin-Biswas's currently scheme and demonstrate the major security loopholes in their works. Next, we propose a lightweight AKA scheme, using symmetric key cryptography based on smart card, which is resilient against all well known security attacks. Furthermore, we prove the scheme accomplishes mutual handshake and session key agreement property securely between the participates involved under BAN (Burrows, Abadi and Needham) logic. Moreover, formal security analysis and simulations are also conducted using AVISPA(Automated Validation of Internet Security Protocols and Applications) to show that our scheme is secure against active and passive attacks. Additionally, performance analysis shows that our proposed scheme is secure and efficient to apply for resource-constrained WSNs.

  20. An Energy Efficient Mutual Authentication and Key Agreement Scheme Preserving Anonymity for Wireless Sensor Networks

    PubMed Central

    Lu, Yanrong; Li, Lixiang; Peng, Haipeng; Yang, Yixian

    2016-01-01

    WSNs (Wireless sensor networks) are nowadays viewed as a vital portion of the IoTs (Internet of Things). Security is a significant issue in WSNs, especially in resource-constrained environments. AKA (Authentication and key agreement) enhances the security of WSNs against adversaries attempting to get sensitive sensor data. Various AKA schemes have been developed for verifying the legitimate users of a WSN. Firstly, we scrutinize Amin-Biswas’s currently scheme and demonstrate the major security loopholes in their works. Next, we propose a lightweight AKA scheme, using symmetric key cryptography based on smart card, which is resilient against all well known security attacks. Furthermore, we prove the scheme accomplishes mutual handshake and session key agreement property securely between the participates involved under BAN (Burrows, Abadi and Needham) logic. Moreover, formal security analysis and simulations are also conducted using AVISPA(Automated Validation of Internet Security Protocols and Applications) to show that our scheme is secure against active and passive attacks. Additionally, performance analysis shows that our proposed scheme is secure and efficient to apply for resource-constrained WSNs. PMID:27338382

  1. Provably secure identity-based identification and signature schemes from code assumptions

    PubMed Central

    Zhao, Yiming

    2017-01-01

    Code-based cryptography is one of few alternatives supposed to be secure in a post-quantum world. Meanwhile, identity-based identification and signature (IBI/IBS) schemes are two of the most fundamental cryptographic primitives, so several code-based IBI/IBS schemes have been proposed. However, with increasingly profound researches on coding theory, the security reduction and efficiency of such schemes have been invalidated and challenged. In this paper, we construct provably secure IBI/IBS schemes from code assumptions against impersonation under active and concurrent attacks through a provably secure code-based signature technique proposed by Preetha, Vasant and Rangan (PVR signature), and a security enhancement Or-proof technique. We also present the parallel-PVR technique to decrease parameter values while maintaining the standard security level. Compared to other code-based IBI/IBS schemes, our schemes achieve not only preferable public parameter size, private key size, communication cost and signature length due to better parameter choices, but also provably secure. PMID:28809940

  2. Gender and power contestations over water use in irrigation schemes: Lessons from the lake Chilwa basin

    NASA Astrophysics Data System (ADS)

    Nkhoma, Bryson; Kayira, Gift

    2016-04-01

    Over the past two decades, Malawi has been adversely hit by climatic variability and changes, and irrigation schemes which rely mostly on water from rivers have been negatively affected. In the face of dwindling quantities of water, distribution and sharing of water for irrigation has been a source of contestations and conflicts. Women who constitute a significant section of irrigation farmers in schemes have been major culprits. The study seeks to analyze gender contestations and conflicts over the use of water in the schemes developed in the Lake Chilwa basin, in southern Malawi. Using oral and written sources as well as drawing evidence from participatory and field observations conducted at Likangala and Domasi irrigation schemes, the largest schemes in the basin, the study observes that women are not passive victims of male domination over the use of dwindling waters for irrigation farming. They have often used existing political and traditional structures developed in the management of water in the schemes to competitively gain monopoly over water. They have sometimes expressed their agency by engaging in irrigation activities that fall beyond the control of formal rules and regulations of irrigation agriculture. Other than being losers, women are winning the battle for water and land resources in the basin.

  3. Costs and economic consequences of a help-at-home scheme for older people in England.

    PubMed

    Bauer, Annette; Knapp, Martin; Wistow, Gerald; Perkins, Margaret; King, Derek; Iemmi, Valentina

    2017-03-01

    Solutions to support older people to live independently and reduce the cost of an ageing population are high on the political agenda of most developed countries. Help-at-home schemes offer a mix of community support with the aim to address a range of well-being needs. However, not much is currently known about the costs, outcomes and economic consequences of such schemes. Understanding their impact on individuals' well-being and the economic consequences for local and central government can contribute to decisions about sustainable long-term care financing. This article presents results from a mixed-methods study of a voluntary sector-provided help-at-home scheme in England for people of 55 years and older. The study followed a participatory approach, which involved staff and volunteers. Data were collected during 2012 and 2013. Social care-related quality of life was measured with the Adult Social Care Outcomes Toolkit for 24 service users (59% response rate) when they started using the scheme and 4-6 months later. A customised questionnaire that captured resource use and well-being information was sent to 1064 service users (63% response rate). The same tool was used in assessment with service users who started using the scheme between November 2012 and April 2013 (100% response rate). Costs of the scheme were established from local budget and activity data. The scheme was likely to achieve a mean net benefit of £1568 per person from a local government and National Health Service (NHS) perspective and £3766 from the perspective of the individual. An expenditure of £2851 per person accrued to central government for the additional redistribution of benefit payments to older people. This article highlights the potential contribution of voluntary sector-run help-at-home schemes to an affordable welfare system for ageing societies.

  4. Multidimensional explicit difference schemes for hyperbolic conservation laws

    NASA Technical Reports Server (NTRS)

    Van Leer, B.

    1984-01-01

    First- and second-order explicit difference schemes are derived for a three-dimensional hyperbolic system of conservation laws, without recourse to dimensional factorization. All schemes are upwind biased and optimally stable.

  5. Multidimensional explicit difference schemes for hyperbolic conservation laws

    NASA Technical Reports Server (NTRS)

    Vanleer, B.

    1983-01-01

    First and second order explicit difference schemes are derived for a three dimensional hyperbolic system of conservation laws, without recourse to dimensional factorization. All schemes are upwind (backward) biased and optimally stable.

  6. An efficient and provably secure proxy signature scheme

    NASA Astrophysics Data System (ADS)

    Zhang, Jianhong; Liu, Xue; Gao, Shengnan

    2010-08-01

    Proxy signature is a special signature, it allows an original signer to delegate her signing capability to a proxy signer and the proxy signer can produce a signature on behalf of the original signer. At present, most of proxy signature in essence consists of two signatures. To overcome the problem, we propose a short efficient proxy signature scheme based on a certificateless signature scheme. And we show that the proposed scheme is secure in the random oracle model. The security of the scheme is related to Inverse Computational Diffie-Hellman Problem and the k-CCA problem. Comparison with Huang et.al scheme, our scheme has an advantage over Huang et.al's scheme in terms of the size of proxy signature. Since the length of proxy signature in our scheme is 160bit, it is very suitable for mobile devices.

  7. Minimal dissipation hybrid bicompact schemes for hyperbolic equations

    NASA Astrophysics Data System (ADS)

    Bragin, M. D.; Rogov, B. V.

    2016-06-01

    New monotonicity-preserving hybrid schemes are proposed for multidimensional hyperbolic equations. They are convex combinations of high-order accurate central bicompact schemes and upwind schemes of first-order accuracy in time and space. The weighting coefficients in these combinations depend on the local difference between the solutions produced by the high- and low-order accurate schemes at the current space-time point. The bicompact schemes are third-order accurate in time, while having the fourth order of accuracy and the first difference order in space. At every time level, they can be solved by marching in each spatial variable without using spatial splitting. The upwind schemes have minimal dissipation among all monotone schemes constructed on a minimum space-time stencil. The hybrid schemes constructed has been successfully tested as applied to a number of two-dimensional gas dynamics benchmark problems.

  8. Parallelization of implicit finite difference schemes in computational fluid dynamics

    NASA Technical Reports Server (NTRS)

    Decker, Naomi H.; Naik, Vijay K.; Nicoules, Michel

    1990-01-01

    Implicit finite difference schemes are often the preferred numerical schemes in computational fluid dynamics, requiring less stringent stability bounds than the explicit schemes. Each iteration in an implicit scheme involves global data dependencies in the form of second and higher order recurrences. Efficient parallel implementations of such iterative methods are considerably more difficult and non-intuitive. The parallelization of the implicit schemes that are used for solving the Euler and the thin layer Navier-Stokes equations and that require inversions of large linear systems in the form of block tri-diagonal and/or block penta-diagonal matrices is discussed. Three-dimensional cases are emphasized and schemes that minimize the total execution time are presented. Partitioning and scheduling schemes for alleviating the effects of the global data dependencies are described. An analysis of the communication and the computation aspects of these methods is presented. The effect of the boundary conditions on the parallel schemes is also discussed.

  9. Invariant Discretization Schemes Using Evolution-Projection Techniques

    NASA Astrophysics Data System (ADS)

    Bihlo, Alexander; Nave, Jean-Christophe

    2013-08-01

    Finite difference discretization schemes preserving a subgroup of the maximal Lie invariance group of the one-dimensional linear heat equation are determined. These invariant schemes are constructed using the invariantization procedure for non-invariant schemes of the heat equation in computational coordinates. We propose a new methodology for handling moving discretization grids which are generally indispensable for invariant numerical schemes. The idea is to use the invariant grid equation, which determines the locations of the grid point at the next time level only for a single integration step and then to project the obtained solution to the regular grid using invariant interpolation schemes. This guarantees that the scheme is invariant and allows one to work on the simpler stationary grids. The discretization errors of the invariant schemes are established and their convergence rates are estimated. Numerical tests are carried out to shed some light on the numerical p! roperties of invariant discretization schemes using the proposed evolution-projection strategy.

  10. Scanning schemes in white light photoelasticity - Part II: Novel fringe resolution guided scanning scheme

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Vivek; Ramesh, K.

    2017-05-01

    Varied spatial resolution of isochromatic fringes over the domain influences the accuracy of fringe order estimation using TFP/RGB photoelasticity. This has been brought out in the first part of the work. The existing scanning schemes do not take this into account, which leads to the propagation of noise from the low spatial resolution zones. In this paper, a method is proposed for creating a whole field map which represents the spatial resolution of the isochromatic fringe pattern. A novel scanning scheme is then proposed whose progression is guided by the spatial resolution of the fringes in the isochromatic image. The efficacy of the scanning scheme is demonstrated using three problems - an inclined crack under bi-axial loading, a thick ring subjected to internal pressure and a stress frozen specimen of an aerospace component. The proposed scheme has use in a range of applications. The scanning scheme is effective even if the model has random zones of noise which is demonstrated using a plate subjected to concentrated load. This aspect is well utilised to extract fringe data from thin slices cut from a stereo-lithographic model that has characteristic random noise due to layered manufacturing.

  11. Security Analysis of Liu-Li Digital Signature Scheme

    NASA Astrophysics Data System (ADS)

    Liu, Chenglian; Zhang, Jianghong; Deng, Shaoyi

    In 2008, Liu and Li proposed a digital signature scheme without using one-way hash function and message redundancy. They claimed their scheme are more efficient in computation and communication for small device. In this paper, we will point out an new attack to certain the Liu-Li scheme is insecure. Then we give an improvement, this scheme is suitable for low power computation and mobile device.

  12. Dually-Perturbed Matsumoto-Imai Signature (DPMS) Scheme

    NASA Astrophysics Data System (ADS)

    Gotaishi, Masahito; Tadaki, Kohtaro; Fujita, Ryo; Tsujii, Shigeo

    A new signature scheme of MPKC is proposed. It is created by perturbing a traditional encryption scheme in two ways. The proposed perturbation polynomials successfully reinforce the Matsumoto-Imai cryptosystem This new signature scheme has a structure very difficult to cryptanalyze. Along with the security against algebraic attacks, its security against existing attacks is discussed. The experimental data imply that the scheme can create a both lightweight and secure signature system.

  13. Tailoring explicit time-marching schemes to improve convergence characteristics

    NASA Technical Reports Server (NTRS)

    Powell, Kenneth G.; Vanleer, Bram

    1990-01-01

    Multi-stage time-stepping schemes, tailored to chosen spatial-differencing operators, are derived and tested. The schemes are constructed to give optimal damping of the high-frequency waves. They are ideal for use with multi-grid acceleration. The concept of characteristic time-stepping, necessary for the extension of the scalar analysis to systems of equations, is presented. The schemes show a marked improvement over Runge-Kutta schemes.

  14. Connection Between the Lattice Boltzmann Equation and the Beam Scheme

    NASA Technical Reports Server (NTRS)

    Xu, Kun; Luo, Li-Shi

    1999-01-01

    In this paper we analyze and compare the lattice Boltzmann equation with the beam scheme in details. We notice the similarity and differences between the lattice Boltzmann equation and the beam scheme. We show that the accuracy of the lattice Boltzmann equation is indeed second order in space. We discuss the advantages and limitations of lattice Boltzmann equation and the beam scheme. Based on our analysis, we propose an improved multi-dimensional beam scheme.

  15. A Gas-Kinetic Scheme for Turbulent Flow

    DTIC Science & Technology

    2014-09-19

    belong to a class of their own of numerical schemes for fluid mechanics. These schemes are neither particle methods, such as DSMC and Molecular...consistent mathematical model of fluid mechanics. Gas-kinetic schemes are more accurate than conventional schemes, and might be able to resolve shock...the heath flux must therefore be corrected for realistic fluids . A number of publications ([Li et al., 2010, Xu et al., 2005, Xuan and Xu, 2012] and

  16. High order discretization schemes for the CIR process

    NASA Astrophysics Data System (ADS)

    Alfonsi, Aurelien

    2010-01-01

    This paper presents weak second and third order schemes for the Cox-Ingersoll-Ross (CIR) process, without any restriction on its parameters. At the same time, it gives a general recursive construction method for getting weak second order schemes that extend the one introduced by Ninomiya and Victoir. Combine both these results, this allows us to propose a second order scheme for more general affine diffusions. Simulation examples are given to illustrate the convergence of these schemes on CIR and Heston models.

  17. Color encryption scheme based on adapted quantum logistic map

    NASA Astrophysics Data System (ADS)

    Zaghloul, Alaa; Zhang, Tiejun; Amin, Mohamed; Abd El-Latif, Ahmed A.

    2014-04-01

    This paper presents a new color image encryption scheme based on quantum chaotic system. In this scheme, a new encryption scheme is accomplished by generating an intermediate chaotic key stream with the help of quantum chaotic logistic map. Then, each pixel is encrypted by the cipher value of the previous pixel and the adapted quantum logistic map. The results show that the proposed scheme has adequate security for the confidentiality of color images.

  18. Combined Space and Time Adaptivity Using the WAMR/G-Scheme Method

    NASA Astrophysics Data System (ADS)

    Zikoski, Zachary; Paolucci, Samuel; Valorani, Mauro

    2009-11-01

    Adaptive methods in CFD allow for savings in execution time by reducing the number of unknowns solved for at each computational step. The Wavelet Adaptive Multiresolution Representation (WAMR) provides spatial adaptivity which automatically supplies grid resolution based on the local demands of the solution itself. Likewise, the G-Scheme framework applies a similar capability in time. A system of ODEs can be ordered and separated into subsets of ``fast'' or near-equilibrium modes, ``slow'' or frozen modes, and ``active'' intermediate modes. Only the active modes are integrated, with asymptotics accounting for the contributions of the slow and fast dynamics. The pairing of spatial adaptivity using the WAMR method and temporal adaptivity using the G-Scheme allows for a substantial reduction in space-time degrees of freedom needed. The combined WAMR/G-scheme method is applied to several problems including reactive, compressible flow simulations.

  19. 33 CFR 83.10 - Traffic separation schemes (Rule 10).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Traffic separation schemes (Rule... Visibility § 83.10 Traffic separation schemes (Rule 10). (a) Obligations under other Rules unaffected. This Rule applies to traffic separation schemes and does not relieve any vessel of her obligation under...

  20. 33 CFR 83.10 - Traffic separation schemes (Rule 10).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Traffic separation schemes (Rule... Visibility § 83.10 Traffic separation schemes (Rule 10). (a) Obligations under other Rules unaffected. This Rule applies to traffic separation schemes and does not relieve any vessel of her obligation under...

  1. 33 CFR 83.10 - Traffic separation schemes (Rule 10).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Traffic separation schemes (Rule... Visibility § 83.10 Traffic separation schemes (Rule 10). (a) Obligations under other Rules unaffected. This Rule applies to traffic separation schemes and does not relieve any vessel of her obligation under...

  2. 33 CFR 83.10 - Traffic separation schemes (Rule 10).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Traffic separation schemes (Rule... Visibility § 83.10 Traffic separation schemes (Rule 10). (a) Obligations under other Rules unaffected. This Rule applies to traffic separation schemes and does not relieve any vessel of her obligation under...

  3. 33 CFR 83.10 - Traffic separation schemes (Rule 10).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Traffic separation schemes (Rule... Visibility § 83.10 Traffic separation schemes (Rule 10). (a) Obligations under other Rules unaffected. This Rule applies to traffic separation schemes and does not relieve any vessel of her obligation under...

  4. Forgery attack to Kang-Tang digital signature scheme

    NASA Astrophysics Data System (ADS)

    Fang, Jie; Guo, Yongning; Liu, Chenglian

    2014-10-01

    In 2006, Kang and Tang proposed a digital signature scheme without hash functions and message redundancy. They claimed their scheme are more efficient in computation and communication for small device. In this paper, we will point out an new attack to certain the Kang-Tang scheme is insecure.

  5. On the strong monotonicity of the CABARET scheme

    NASA Astrophysics Data System (ADS)

    Ostapenko, V. V.

    2012-03-01

    The strong monotonicity of the CABARET scheme with single flux correction is analyzed as applied to the linear advection equation. It is shown that the scheme is strongly monotone (has the NED property) at Courant numbers r ∈ (0,0,5), for which it is monotone. Test computations illustrating this property of the CABARET scheme are presented.

  6. Analysis of some bivariate non-linear interpolatory subdivision schemes

    NASA Astrophysics Data System (ADS)

    Dadourian, Karine; Liandrat, Jacques

    2008-07-01

    This paper is devoted to the convergence analysis of a class of bivariate subdivision schemes that can be defined as a specific perturbation of a linear subdivision scheme. We study successively the univariate and bivariate case and apply the analysis to the so called Powerp scheme (Serna and Marquina, J Comput Phys 194:632-658, 2004).

  7. Dispersion-relation-preserving schemes for computational aeroacoustics

    NASA Technical Reports Server (NTRS)

    Tam, Christopher K. W.; Webb, Jay C.

    1992-01-01

    Finite difference schemes that have the same dispersion relations as the original partial differential equations are referred to as dispersion-relation-preserving (DRP) schemes. A method to construct time marching DRP schemes by optimizing the finite difference approximations of the space and time derivatives in the wave number and frequency space is presented. A sequence of numerical simulations is then performed.

  8. 7 CFR 1430.610 - Misrepresentation and scheme or device.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Misrepresentation and scheme or device. 1430.610... Disaster Assistance Payment Program II (DDAP-II) § 1430.610 Misrepresentation and scheme or device. (a) In... this part to any person or operation engaged in a misrepresentation, scheme, or device, must be...

  9. 33 CFR 167.15 - Modification of schemes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    .... (a) A traffic separation scheme or precautionary area described in this Part may be permanently... traffic separation scheme or precautionary area in this Part may be temporarily adjusted by the Commandant... temporary suspension of a section of the scheme, a temporary precautionary area overlaying a lane, or other...

  10. A homomorphic arithmetic scheme on real number with fixed precision

    NASA Astrophysics Data System (ADS)

    Bai, Liwang; Lan, Yuqing

    2017-05-01

    Existing homomorphic encryption schemes are limited in plaintext space, that they cannot be directly applied to actual scenes. Based on the homomorphic encryption scheme of single-bit plaintext, this paper presents a homomorphic arithmetic scheme on multi-bit plaintext, to apply the arithmetic operation of the real number with fixed precision.

  11. Dispersion-relation-preserving schemes for computational aeroacoustics

    NASA Technical Reports Server (NTRS)

    Tam, Christopher K. W.; Webb, Jay C.

    1992-01-01

    Finite difference schemes that have the same dispersion relations as the original partial differential equations are referred to as dispersion-relation-preserving (DRP) schemes. A method to construct time marching DRP schemes by optimizing the finite difference approximations of the space and time derivatives in the wave number and frequency space is presented. A sequence of numerical simulations is then performed.

  12. Taxonomic scheme for the identification of marine bacteria

    NASA Astrophysics Data System (ADS)

    Oliver, James D.

    1982-06-01

    A recently developed taxonomic scheme for the identification of marine bacteria is presented. The scheme is based on numerous reviews and monographs on marine bacteria, as well as Bergey's Manual of Determinative Bacteriology. While fairly extensive, the scheme is designed to identify marine bacteria using relatively few tests.

  13. Developing and Rewarding Excellent Teachers: The Scottish Chartered Teacher Scheme

    ERIC Educational Resources Information Center

    Ingvarson, Lawrence

    2009-01-01

    The Scottish Chartered Teacher Scheme was designed to recognise and reward teachers who attained high standards of practice. The scheme emerged in 2001 as part of an agreement between government, local employing authorities and teacher organisations. Policies such as the chartered teacher scheme aim to benefit students in two main ways: by…

  14. The Pharmaceutical Benefits Scheme 2003-2004.

    PubMed

    Harvey, Ken J

    2005-01-12

    The Pharmaceutical Benefits Scheme (PBS) grew by 8% in 2003-04; a slower rate than the 12.0% pa average growth over the last decade. Nevertheless, the sustainability of the Scheme remained an ongoing concern given an aging population and the continued introduction of useful (but increasingly expensive) new medicines. There was also concern that the Australia-United States Free Trade Agreement could place further pressure on the Scheme. In 2003, as in 2002, the government proposed a 27% increase in PBS patient co-payments and safety-net thresholds in order to transfer more of the cost of the PBS from the government to consumers. While this measure was initially blocked by the Senate, the forthcoming election resulted in the Labor Party eventually supporting this policy. Recommendations of the Pharmaceutical Benefits Advisory Committee to list, not list or defer a decision to list a medicine on the PBS were made publicly available for the first time and the full cost of PBS medicines appeared on medicine labels if the price was greater than the co-payment. Pharmaceutical reform in Victorian public hospitals designed to minimise PBS cost-shifting was evaluated and extended to other States and Territories. Programs promoting the quality use of medicines were further developed coordinated by the National Prescribing Service, Australian Divisions of General Practice and the Pharmacy Guild of Australia. The extensive uptake of computerised prescribing software by GPs produced benefits but also problems. The latter included pharmaceutical promotion occurring at the time of prescribing, failure to incorporate key sources of objective therapeutic information in the software and gross variation in the ability of various programs to detect important drug-drug interactions. These issues remain to be tackled.

  15. Proposal for a Small Scheme Implementation.

    DTIC Science & Technology

    1984-10-01

    5,-s Accession For ...- NTIS GRA&I DTIC TAB Unannounced ,,-- ,.. Justification By Avaii1," lit-- .c-des Dist j Sp-cio 0U . 8STD S. / Un~lasmiffied P’O...8217 IS[CUNITY CLASLSIICATIO#4 O P THIS PA O6I(I~ . 0.1. Eatoure ) Proposal for a Small Scheme Implementation, by "" Richard Schooler and James W...built.in routines. The garbage collector also needs to distinguish pointers from immediate data. To simplify ~.- "’ p . ’.s garbage collection and permit

  16. A Classification Scheme for Glaciological AVA Responses

    NASA Astrophysics Data System (ADS)

    Booth, A.; Emir, E.

    2014-12-01

    A classification scheme is proposed for amplitude vs. angle (AVA) responses as an aid to the interpretation of seismic reflectivity in glaciological research campaigns. AVA responses are a powerful tool in characterising the material properties of glacier ice and its substrate. However, before interpreting AVA data, careful true amplitude processing is required to constrain basal reflectivity and compensate amplitude decay mechanisms, including anelastic attenuation and spherical divergence. These fundamental processing steps can be difficult to design in cases of noisy data, e.g. where a target reflection is contaminated by surface wave energy (in the case of shallow glaciers) or by energy reflected from out of the survey plane. AVA methods have equally powerful usage in estimating the fluid fill of potential hydrocarbon reservoirs. However, such applications seldom use true amplitude data and instead consider qualitative AVA responses using a well-defined classification scheme. Such schemes are often defined in terms of the characteristics of best-fit responses to the observed reflectivity, e.g. the intercept (I) and gradient (G) of a linear approximation to the AVA data. The position of the response on a cross-plot of I and G then offers a diagnostic attribute for certain fluid types. We investigate the advantages in glaciology of emulating this practice, and develop a cross-plot based on the 3-term Shuey AVA approximation (using I, G, and a curvature term C). Model AVA curves define a clear lithification trend: AVA responses to stiff (lithified) substrates fall discretely into one quadrant of the cross-plot, with positive I and negative G, whereas those to fluid-rich substrates plot diagonally opposite (in the negative I and positive G quadrant). The remaining quadrants are unoccupied by plausible single-layer responses and may therefore be diagnostic of complex thin-layer reflectivity, and the magnitude and polarity of the C term serves as a further indicator

  17. Cosmological SUSY Breaking and the Pyramid Scheme

    NASA Astrophysics Data System (ADS)

    Banks, Tom

    2014-12-01

    I review the ideas of holographic space-time (HST), Cosmological SUSY breaking (CSB), and the Pyramid Schemes, which are the only known models of Tera-scale physics consistent with CSB, current particle data, and gauge coupling unification. There is considerable uncertainty in the estimate of the masses of supersymmetric partners of the standard model particles, but the model predicts that the gluino is probably out of reach of the LHC, squarks may be in reach, and the NLSP is a right handed slepton, which should be discovered soon.

  18. Cosmological SUSY breaking and the pyramid scheme

    NASA Astrophysics Data System (ADS)

    Banks, Tom

    2015-04-01

    I review the ideas of holographic spacetime (HST), cosmological SUSY breaking (CSB), and the Pyramid Schemes, which are the only known models of Tera-scale physics consistent with CSB, current particle data, and gauge coupling unification. There is considerable uncertainty in the estimate of the masses of supersymmetric partners of the Standard Model particles, but the model predicts that the gluino is probably out of reach of the LHC, squarks may be in reach, and the NLSP is a right-handed slepton, which should be discovered soon.

  19. Secure Biometric E-Voting Scheme

    NASA Astrophysics Data System (ADS)

    Ahmed, Taha Kh.; Aborizka, Mohamed

    The implementation of the e-voting becomes more substantial with the rapid increase of e-government development. The recent growth in communications and cryptographic techniques facilitate the implementation of e-voting. Many countries introduced e-voting systems; unfortunately most of these systems are not fully functional. In this paper we will present an e-voting scheme that covers most of the e-voting requirements, smart card and biometric recognition technology were implemented to guarantee voter's privacy and authentication.

  20. Numerical Schemes for Rough Parabolic Equations

    SciTech Connect

    Deya, Aurelien

    2012-04-15

    This paper is devoted to the study of numerical approximation schemes for a class of parabolic equations on (0,1) perturbed by a non-linear rough signal. It is the continuation of Deya (Electron. J. Probab. 16:1489-1518, 2011) and Deya et al. (Probab. Theory Relat. Fields, to appear), where the existence and uniqueness of a solution has been established. The approach combines rough paths methods with standard considerations on discretizing stochastic PDEs. The results apply to a geometric 2-rough path, which covers the case of the multidimensional fractional Brownian motion with Hurst index H>1/3.

  1. Investigation of a monochromator scheme for SPEAR

    SciTech Connect

    Wille, K.; Chao, A.W.

    1984-08-01

    The possibility of mono-chromatizing SPEAR for the purpose of increasing the hadronic event rate at the narrow resonances was investigated. By using two pairs of electostatic skew quads in monochromator scheme it is found that the event rate can be increased by a factor of 2 for the mini beta optics assuming the luminosity is kept unchanged. An attempt to increase this enhancement factor by major rearrangements of the ring magnets has encountered serious optical difficulties; although enhancement factor of 8 seems possible in principle, this alternative is not recommended.

  2. Different Synchronization Schemes for Chaotic Rikitake Systems

    NASA Astrophysics Data System (ADS)

    Khan, M. Ali

    2013-06-01

    This paper presents the chaos synchronization by designing a different type of controllers. Firstly, we propose the synchronization of bi-directional coupled chaotic Rikitake systems via hybrid feedback control. Secondly, we study the synchronization of unidirectionally coupled Rikitake systems using hybrid feedback control. Lastly, we investigate the synchronization of unidirectionally coupled Rikitake chaotic systems using tracking control. Comparing all the results, finally, we conclude that tracking control is more effective than feedback control. Simulation results are presented to show the efficiency of synchronization schemes.

  3. A numerical scheme for ionizing shock waves

    SciTech Connect

    Aslan, Necdet . E-mail: naslan@yeditepe.edu.tr; Mond, Michael

    2005-12-10

    A two-dimensional (2D) visual computer code to solve the steady state (SS) or transient shock problems including partially ionizing plasma is presented. Since the flows considered are hypersonic and the resulting temperatures are high, the plasma is partially ionized. Hence the plasma constituents are electrons, ions and neutral atoms. It is assumed that all the above species are in thermal equilibrium, namely, that they all have the same temperature. The ionization degree is calculated from Saha equation as a function of electron density and pressure by means of a nonlinear Newton type root finding algorithms. The code utilizes a wave model and numerical fluctuation distribution (FD) scheme that runs on structured or unstructured triangular meshes. This scheme is based on evaluating the mesh averaged fluctuations arising from a number of waves and distributing them to the nodes of these meshes in an upwind manner. The physical properties (directions, strengths, etc.) of these wave patterns are obtained by a new wave model: ION-A developed from the eigen-system of the flux Jacobian matrices. Since the equation of state (EOS) which is used to close up the conservation laws includes electronic effects, it is a nonlinear function and it must be inverted by iterations to determine the ionization degree as a function of density and temperature. For the time advancement, the scheme utilizes a multi-stage Runge-Kutta (RK) algorithm with time steps carefully evaluated from the maximum possible propagation speed in the solution domain. The code runs interactively with the user and allows to create different meshes to use different initial and boundary conditions and to see changes of desired physical quantities in the form of color and vector graphics. The details of the visual properties of the code has been published before (see [N. Aslan, A visual fluctuation splitting scheme for magneto-hydrodynamics with a new sonic fix and Euler limit, J. Comput. Phys. 197 (2004) 1

  4. A stellar-inertial navigation scheme

    NASA Astrophysics Data System (ADS)

    Yim, Jong-bin; Lim, You-chol; Lyou, Joon

    2005-12-01

    Since inertial sensor errors which increase with time are caused by initial orientation error and sensor errors(accelerometer bias and gyro drift bias), the accuracy of these devices, while still improving, is not adequate for many of today's high-precision, long-duration sea, aircraft, and long-range flight missions. This paper presented a navigation error compensation scheme for Strap-Down Inertial Navigation System(SDINS) using Electro-optical sensor. To be specific, SDINS error model and measurement equation were derived, and Kalman filter was implemented. Simulation results show the boundedness of position and attitude errors.

  5. Apiary B-Factory separation scheme

    SciTech Connect

    Garren, A. ); Sullivan, M. )

    1991-04-01

    A magnetic beam-separation scheme for an asymmetric-energy B-Factory based on the SLAC electron-positron collider PEP is described that has the following properties: the beams collide head-on and are separated magnetically with sufficient clearance at the parasitic crossing points and at the septum, the magnets have large beam-stay-clear apertures, synchrotron radiation produces low detector backgrounds and acceptable heat loads, and the peak {beta}-function values and contributions to the chromaticities in the IR quadrupoles are moderate. 8 figs., 2 tabs.

  6. Rabi resonances in the {lambda} excitation scheme

    SciTech Connect

    Godone, Aldo; Micalizio, Salvatore; Levi, Filippo

    2002-12-01

    We consider the interaction of a three-level system with phase-modulated resonant fields in the {lambda} excitation scheme. We treat theoretically the case of a sinusoidal phase modulation, a phase step perturbation, and a stochastic phase modulation. The appearance of a Rabi resonance both in the spectrum of the optical transmitted signal (electromagnetically induced transparency) and in the spectrum of the microwave emission (coherent population trapping maser) is considered in detail. All the theoretical results are compared with the analogous ones reported for the two-level system and with our experimental observations obtained for the case of rubidium in a buffer gas.

  7. APIARY B-Factory Separation Scheme

    SciTech Connect

    Garren, A.; Sullivan, M.

    1991-05-03

    A magnetic beam-separation scheme for an asymmetric-energy B Factory based on the SLAC electron-positron collider PEP is described that has the following properties: the beams collide head-on and are separated magnetically with sufficient clearance at the parasitic crossing points and at the septum, the magnets have large beam-stay-clear apertures, synchrotron radiation produces low detector backgrounds and acceptable heat loads, and the peak {beta}-function values and contributions to the chromaticities in the IR quadrupoles are moderate.

  8. Vehicle scheduling schemes for commercial and emergency logistics integration.

    PubMed

    Li, Xiaohui; Tan, Qingmei

    2013-01-01

    In modern logistics operations, large-scale logistics companies, besides active participation in profit-seeking commercial business, also play an essential role during an emergency relief process by dispatching urgently-required materials to disaster-affected areas. Therefore, an issue has been widely addressed by logistics practitioners and caught researchers' more attention as to how the logistics companies achieve maximum commercial profit on condition that emergency tasks are effectively and performed satisfactorily. In this paper, two vehicle scheduling models are proposed to solve the problem. One is a prediction-related scheme, which predicts the amounts of disaster-relief materials and commercial business and then accepts the business that will generate maximum profits; the other is a priority-directed scheme, which, firstly groups commercial and emergency business according to priority grades and then schedules both types of business jointly and simultaneously by arriving at the maximum priority in total. Moreover, computer-based simulations are carried out to evaluate the performance of these two models by comparing them with two traditional disaster-relief tactics in China. The results testify the feasibility and effectiveness of the proposed models.

  9. Vehicle Scheduling Schemes for Commercial and Emergency Logistics Integration

    PubMed Central

    Li, Xiaohui; Tan, Qingmei

    2013-01-01

    In modern logistics operations, large-scale logistics companies, besides active participation in profit-seeking commercial business, also play an essential role during an emergency relief process by dispatching urgently-required materials to disaster-affected areas. Therefore, an issue has been widely addressed by logistics practitioners and caught researchers' more attention as to how the logistics companies achieve maximum commercial profit on condition that emergency tasks are effectively and performed satisfactorily. In this paper, two vehicle scheduling models are proposed to solve the problem. One is a prediction-related scheme, which predicts the amounts of disaster-relief materials and commercial business and then accepts the business that will generate maximum profits; the other is a priority-directed scheme, which, firstly groups commercial and emergency business according to priority grades and then schedules both types of business jointly and simultaneously by arriving at the maximum priority in total. Moreover, computer-based simulations are carried out to evaluate the performance of these two models by comparing them with two traditional disaster-relief tactics in China. The results testify the feasibility and effectiveness of the proposed models. PMID:24391724

  10. Regulatory schemes to achieve optimal flux partitioning in bacterial metabolism

    NASA Astrophysics Data System (ADS)

    Tang, Lei-Han; Yang, Zhu; Hui, Sheng; Kim, Pan-Jun; Li, Xue-Fei; Hwa, Terence

    2012-02-01

    The flux balance analysis (FBA) offers a way to compute the optimal performance of a given metabolic network when the maximum incoming flux of nutrient molecules and other essential ingredients for biosynthesis are specified. Here we report a theoretical and computational analysis of the network structure and regulatory interactions in an E. coli cell. An automated scheme is devised to simplify the network topology and to enumerate the independent flux degrees of freedom. The network organization revealed by the scheme enables a detailed interpretation of the three layers of metabolic regulation known in the literature: i) independent transcriptional regulation of biosynthesis and salvage pathways to render the network tree-like under a given nutrient condition; ii) allosteric end-product inhibition of enzyme activity at entry points of synthesis pathways for metabolic flux partitioning according to consumption; iii) homeostasis of currency and carrier compounds to maintain sufficient supply of global commodities. Using the amino-acid synthesis pathways as an example, we show that the FBA result can be reproduced with suitable implementation of the three classes of regulatory interactions with literature evidence.

  11. A new configurational bias scheme for sampling supramolecular structures

    SciTech Connect

    De Gernier, Robin; Mognetti, Bortolo M.; Curk, Tine; Dubacheva, Galina V.; Richter, Ralf P.

    2014-12-28

    We present a new simulation scheme which allows an efficient sampling of reconfigurable supramolecular structures made of polymeric constructs functionalized by reactive binding sites. The algorithm is based on the configurational bias scheme of Siepmann and Frenkel and is powered by the possibility of changing the topology of the supramolecular network by a non-local Monte Carlo algorithm. Such a plan is accomplished by a multi-scale modelling that merges coarse-grained simulations, describing the typical polymer conformations, with experimental results accounting for free energy terms involved in the reactions of the active sites. We test the new algorithm for a system of DNA coated colloids for which we compute the hybridisation free energy cost associated to the binding of tethered single stranded DNAs terminated by short sequences of complementary nucleotides. In order to demonstrate the versatility of our method, we also consider polymers functionalized by receptors that bind a surface decorated by ligands. In particular, we compute the density of states of adsorbed polymers as a function of the number of ligand–receptor complexes formed. Such a quantity can be used to study the conformational properties of adsorbed polymers useful when engineering adsorption with tailored properties. We successfully compare the results with the predictions of a mean field theory. We believe that the proposed method will be a useful tool to investigate supramolecular structures resulting from direct interactions between functionalized polymers for which efficient numerical methodologies of investigation are still lacking.

  12. Continuing medical education for pathologists: an evaluation of the Royal College of Pathologists' Wessex pilot scheme.

    PubMed Central

    du Boulay, C

    1997-01-01

    AIM: To discover the attitudes to continuing medical education (CME) of the Wessex pathologists who participated in the Wessex CME pilot scheme and to identify their preferences and difficulties in pursuing CME activities. METHOD: The views of pathologists in the scheme were collected during a period of one year using workshops and discussions. A confidential, anonymous postal questionnaire based on these issues was sent to the 103 pathologists in Wessex who participated in the pilot scheme. RESULTS: A 64% response rate was obtained. The respondents identified lack of time and funded study leave as major barriers to CME and highlighted the gap between CME activity and its recognition and funding by employers. They wanted a wide variety of locally based CME activities to be recognised, and they valued local activities that linked theory with practice. They believed that the college scheme tended to favour academic activities over more practical and locally based ones. They found the paired peer review process time consuming but valuable for identifying their learning needs in some cases, but demonstrated that they have mixed preferences about the way they do their CME. CONCLUSIONS: The Wessex pathologists believe that CME is important and have positive attitudes to it. Their attitudes to CME echo the current literature about what makes CME effective. Unless individuals' preferences and difficulties are taken into account, CME programmes in which they participate are not likely to succeed. PMID:9516886

  13. A Job Classification Scheme for Health Manpower

    PubMed Central

    Weiss, Jeffrey H.

    1968-01-01

    The Census Bureau's occupational classification scheme and concept of the “health services industry” are inadequate tools for analysis of the changing job structure of health manpower. In an attempt to remedy their inadequacies, a new analytical framework—drawing upon the work of James Scoville on the job content of the U.S. economy—was devised. The first stage in formulating this new framework was to determine which jobs should be considered health jobs. The overall health care job family was designed to encompass jobs in which the primary technical focus or function is oriented toward the provision of health services. There are two dimensions to the job classification scheme presented here. The first describes each job in terms of job content; relative income data and minimum education and training requirements were employed as surrogate measures. By this means, health care jobs were grouped by three levels of job content: high, medium, and low. The other dimension describes each job in terms of its technical focus or function; by this means, health care jobs were grouped into nine job families. PMID:5673666

  14. Evaluation of a vibration source detection scheme

    SciTech Connect

    Jendrzejczyk, J.A.; Wambsganss, M.W.; Smith, R.K.

    1992-04-01

    When the Advanced Photon Source (APS) facility is commissioned, there will be many potential sources of local ground motion excitation (near-field sources). Some of these may be of sufficient amplitude and at a specific frequency so as to be detrimental to the stability of the storage ring beamline. A sampling of possible sources is as follows: 2500-hp chillers in the utility building; six cooling-tower fans that are powered by 75-hp electric motors; various water circulation pumps; power supplies, controllers, and transformers; and air-handling units and associated fans. To detect equipment that causes excessive ground excitation at a site as large as the APS, it will be necessary to have a validated source detection scheme. When performing low-amplitude vibration testing in and around Building 335 of Argonne National Laboratory (ANL), we observed a cyclic 8-Hz vibration. The cyclic nature of the signal is apparent in Fig. 1, which represents data measured on the floor at the main level of Building 335 on March 31, 1992. A simple vibration source location scheme, based on triangulation, was evaluated as a means to locate the source of the 8-Hz vibration and is the subject of this technical note. 1 ref.

  15. Coupling Schemes in Terahertz Planar Metamaterials

    DOE PAGES

    Roy Chowdhury, Dibakar; Singh, Ranjan; Taylor, Antoinette J.; ...

    2012-01-01

    We present a review of the different coupling schemes in a planar array of terahertz metamaterials. The gap-to-gap near-field capacitive coupling between split-ring resonators in a unit cell leads to either blue shift or red shift of the fundamental inductive-capacitive ( LC ) resonance, depending on the position of the split gap. The inductive coupling is enhanced by decreasing the inter resonator distance resulting in strong blue shifts of the LC resonance. We observe the LC resonance tuning only when the split-ring resonators are in close proximity of each other; otherwise, they appear to be uncoupled. Conversely, the higher-ordermore » resonances are sensitive to the smallest change in the inter particle distance or split-ring resonator orientation and undergo tremendous resonance line reshaping giving rise to a sharp subradiant resonance mode which produces hot spots useful for sensing applications. Most of the coupling schemes in a metamaterial are based on a near-field effect, though there also exists a mechanism to couple the resonators through the excitation of lowest-order lattice mode which facilitates the long-range radiative or diffractive coupling in the split-ring resonator plane leading to resonance line narrowing of the fundamental as well as the higher order resonance modes.« less

  16. The Linear Bicharacteristic Scheme for Computational Electromagnetics

    NASA Technical Reports Server (NTRS)

    Beggs, John H.; Chan, Siew-Loong

    2000-01-01

    The upwind leapfrog or Linear Bicharacteristic Scheme (LBS) has previously been implemented and demonstrated on electromagnetic wave propagation problems. This paper extends the Linear Bicharacteristic Scheme for computational electromagnetics to treat lossy dielectric and magnetic materials and perfect electrical conductors. This is accomplished by proper implementation of the LBS for homogeneous lossy dielectric and magnetic media, and treatment of perfect electrical conductors (PECs) are shown to follow directly in the limit of high conductivity. Heterogeneous media are treated through implementation of surface boundary conditions and no special extrapolations or interpolations at dielectric material boundaries are required. Results are presented for one-dimensional model problems on both uniform and nonuniform grids, and the FDTD algorithm is chosen as a convenient reference algorithm for comparison. The results demonstrate that the explicit LBS is a dissipation-free, second-order accurate algorithm which uses a smaller stencil than the FDTD algorithm, yet it has approximately one-third the phase velocity error. The LBS is also more accurate on nonuniform grids.

  17. Lightweight SIP/SDP compression scheme (LSSCS)

    NASA Astrophysics Data System (ADS)

    Wu, Jian J.; Demetrescu, Cristian

    2001-10-01

    In UMTS new IP based services with tight delay constraints will be deployed over the W-CDMA air interface such as IP multimedia and interactive services. To integrate the wireline and wireless IP services, 3GPP standard forum adopted the Session Initiation Protocol (SIP) as the call control protocol for the UMTS Release 5, which will implement next generation, all IP networks for real-time QoS services. In the current form the SIP protocol is not suitable for wireless transmission due to its large message size which will need either a big radio pipe for transmission or it will take far much longer to transmit than the current GSM Call Control (CC) message sequence. In this paper we present a novel compression algorithm called Lightweight SIP/SDP Compression Scheme (LSSCS), which acts at the SIP application layer and therefore removes the information redundancy before it is sent to the network and transport layer. A binary octet-aligned header is added to the compressed SIP/SDP message before sending it to the network layer. The receiver uses this binary header as well as the pre-cached information to regenerate the original SIP/SDP message. The key features of the LSSCS compression scheme are presented in this paper along with implementation examples. It is shown that this compression algorithm makes SIP transmission efficient over the radio interface without losing the SIP generality and flexibility.

  18. Analysis of an antijam FH acquisition scheme

    NASA Astrophysics Data System (ADS)

    Miller, Leonard E.; Lee, Jhong S.; French, Robert H.; Torrieri, Don J.

    1992-01-01

    An easily implemented matched filter scheme for acquiring hopping code synchronization of incoming frequency-hopping (FH) signals is analyzed, and its performance is evaluated for two types of jamming: partial-band noise jamming and partial-band multitone jamming. The system is designed to reduce jammer-induced false alarms. The system's matched-filter output is compared to an adaptive threshold that is derived from a measurement of the number of acquisition channels being jammed. Example performance calculations are given for the frequency coverage of the jamming either fixed over the entire acquisition period or hopped, that is, changed for each acquisition pulse. It is shown that the jammer's optimum strategy (the worst case) is to maximize the false-alarm probability without regard for the effect on detection probability, for both partial-band noise and multi-tone jamming. It is also shown that a significantly lower probability of false acquisition results from using an adaptive matched-filter threshold, demonstrating that the strategy studied here is superior to conventional nonadaptive threshold schemes.

  19. A concatenated coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Lin, S.

    1985-01-01

    A concatenated coding scheme for error control in data communications is analyzed. The inner code is used for both error correction and detection, however the outer code is used only for error detection. A retransmission is requested if the outer code detects the presence of errors after the inner code decoding. The probability of undetected error of the above error control scheme is derived and upper bounded. Two specific exmaples are analyzed. In the first example, the inner code is a distance-4 shortened Hamming code with generator polynomial (X+1)(X(6)+X+1) = X(7)+X(6)+X(2)+1 and the outer code is a distance-4 shortened Hamming code with generator polynomial (X+1)X(15+X(14)+X(13)+X(12)+X(4)+X(3)+X(2)+X+1) = X(16)+X(12)+X(5)+1 which is the X.25 standard for packet-switched data network. This example is proposed for error control on NASA telecommand links. In the second example, the inner code is the same as that in the first example but the outer code is a shortened Reed-Solomon code with symbols from GF(2(8)) and generator polynomial (X+1)(X+alpha) where alpha is a primitive element in GF(z(8)).

  20. Finite-difference schemes for anisotropic diffusion

    SciTech Connect

    Es, Bram van; Koren, Barry; Blank, Hugo J. de

    2014-09-01

    In fusion plasmas diffusion tensors are extremely anisotropic due to the high temperature and large magnetic field strength. This causes diffusion, heat conduction, and viscous momentum loss, to effectively be aligned with the magnetic field lines. This alignment leads to different values for the respective diffusive coefficients in the magnetic field direction and in the perpendicular direction, to the extent that heat diffusion coefficients can be up to 10{sup 12} times larger in the parallel direction than in the perpendicular direction. This anisotropy puts stringent requirements on the numerical methods used to approximate the MHD-equations since any misalignment of the grid may cause the perpendicular diffusion to be polluted by the numerical error in approximating the parallel diffusion. Currently the common approach is to apply magnetic field-aligned coordinates, an approach that automatically takes care of the directionality of the diffusive coefficients. This approach runs into problems at x-points and at points where there is magnetic re-connection, since this causes local non-alignment. It is therefore useful to consider numerical schemes that are tolerant to the misalignment of the grid with the magnetic field lines, both to improve existing methods and to help open the possibility of applying regular non-aligned grids. To investigate this, in this paper several discretization schemes are developed and applied to the anisotropic heat diffusion equation on a non-aligned grid.