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

    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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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...

  7. 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.

  8. 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...

  9. 9 CFR 590.539 - Defrosting operations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 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...

  10. 9 CFR 590.539 - Defrosting operations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 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...

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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...

  20. 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.

  1. 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)

  2. 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.

  3. 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

  4. 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

  5. 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...

  6. 49 CFR 571.103 - Standard No. 103; Windshield defrosting and defogging systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... of SAE Recommended Practice J902, “Passenger Car Windshield Defrosting Systems,” August 1964, when tested in accordance with S4.3, except that “the critical area” specified in paragraph 3.1 of SAE... 3.3 of SAE Recommended Practice J902 shall be that established as Area A in accordance with §...

  7. 49 CFR 571.103 - Standard No. 103; Windshield defrosting and defogging systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... of SAE Recommended Practice J902, “Passenger Car Windshield Defrosting Systems,” August 1964, when tested in accordance with S4.3, except that “the critical area” specified in paragraph 3.1 of SAE... 3.3 of SAE Recommended Practice J902 shall be that established as Area A in accordance with §...

  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. 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.

  11. 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.

  12. 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...

  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, 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...

  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, 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...

  15. 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...

  16. 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...

  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 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...

  19. 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...

  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, 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...

  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. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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…

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  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. 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.

  19. 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).

  20. 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.

  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. 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.

  3. 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.

  4. 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%.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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

    2017-03-15

    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.

  11. 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.

  12. 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…

  13. 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.

  14. 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.

  15. 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…

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  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. 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

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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.

  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. 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

  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. 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.

  17. 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.

  18. 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)

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Difference Schemes and Applications

    DTIC Science & Technology

    2015-02-06

    boundary conditions; - Inverse problems, mathematical theory of active control of sound; -Mathematical modeling in science and engineering...boundary conditions;  Inverse problems, mathematical theory of active control of sound;  Mathematical modeling in science and engineering...Keldysh Institute); he spoke about solving linear inverse problems (e.g., active control of sound) in composite domains using the method

  10. 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.

  11. 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.

  12. 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.

  13. [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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  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. 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.

  6. 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.

  7. 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.

  8. 9 CFR 590.539 - Defrosting operations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Development of a new flux splitting scheme

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    The successful use of a novel splitting scheme, the advection upstream splitting method, for model aerodynamic problems where Van Leer and Roe schemes had failed previously is discussed. The present scheme is based on splitting in which the convective and pressure terms are separated and treated differently depending on the underlying physical conditions. The present method is found to be both simple and accurate.

  3. Development of a new flux splitting scheme

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    The use of a new splitting scheme, the advection upstream splitting method, for model aerodynamic problems where Van Leer and Roe schemes had failed previously is discussed. The present scheme is based on splitting in which the convective and pressure terms are separated and treated differently depending on the underlying physical conditions. The present method is found to be both simple and accurate.

  4. 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.

  5. 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…

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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…

  16. 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…

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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…

  3. 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.

  4. 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.

  5. 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.

  6. Practical formulation of a positively conservative scheme

    NASA Technical Reports Server (NTRS)

    Obayashi, Shigeru; Wada, Yasuhiro

    1994-01-01

    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.

  7. 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).

  8. 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.

  9. 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.

  10. 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.

  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 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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).

  3. 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.

  4. 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.

  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. 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.

  7. 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.

  8. 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.

  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. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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)

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  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. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Steady-State Analysis Model for Advanced Fuel Cycle Schemes.

    SciTech Connect

    SARTORI, ENRICO

    2008-03-17

    Version 00 SMAFS was developed as a part of the study, "Advanced Fuel Cycles and Waste Management", which was performed during 2003-2005 by an ad-hoc expert group under the Nuclear Development Committee in the OECD/NEA. The model was designed for an efficient conduct of nuclear fuel cycle scheme cost analyses. It is simple, transparent and offers users the capability to track down cost analysis results. All the fuel cycle schemes considered in the model are represented in a graphic format and all values related to a fuel cycle step are shown in the graphic interface, i.e., there are no hidden values embedded in the calculations. All data on the fuel cycle schemes considered in the study including mass flows, waste generation, cost data, and other data such as activities, decay heat and neutron sources of spent fuel and high-level waste along time are included in the model and can be displayed. The user can easily modify values of mass flows and/or cost parameters and see corresponding changes in the results. The model calculates: front-end fuel cycle mass flows such as requirements of enrichment and conversion services and natural uranium; mass of waste based on the waste generation parameters and the mass flow; and all costs.

  11. Steady-state Analysis Model for Advanced Fuelcycle Schemes

    SciTech Connect

    2006-05-12

    The model was developed as a part of the study, "Advanced Fuel Cycles and Waste Management", which was performed during 2003—2005 by an ad-hoc expert group under the Nuclear Development Committee in the OECD/NEA. The model was designed for an efficient conduct of nuclear fuel cycle scheme cost analyses. It is simple, transparent and offers users the capability to track down the cost analysis results. All the fuel cycle schemes considered in the model are represented in a graphic format and all values related to a fuel cycle step are shown in the graphic interface, i.e., there are no hidden values embedded in the calculations. All data on the fuel cycle schemes considered in the study including mass flows, waste generation, cost data, and other data such as activities, decay heat and neutron sources of spent fuel and high—level waste along time are included in the model and can be displayed. The user can modify easily the values of mass flows and/or cost parameters and see the corresponding changes in the results. The model calculates: front—end fuel cycle mass flows such as requirements of enrichment and conversion services and natural uranium; mass of waste based on the waste generation parameters and the mass flow; and all costs. It performs Monte Carlo simulations with changing the values of all unit costs within their respective ranges (from lower to upper bounds).

  12. 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.

  13. 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.

  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. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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…

  20. 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.

  1. 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.

  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. 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.

  4. 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.

  5. 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…

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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).

  11. 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).

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  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. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. An improved WENO-Z scheme

    NASA Astrophysics Data System (ADS)

    Acker, F.; B. de R. Borges, R.; Costa, B.

    2016-05-01

    In this article, we show that for a WENO scheme to improve the numerical resolution of smooth waves, increasing to some extent the contribution of the substencils where the solution is less smooth is much more important than improving the accuracy at critical points. WENO-Z, for instance, achieved less dissipative results than classical WENO through the use of a high-order global smoothness measurement, τ, which increased the weights of less-smooth substencils. This time, we present a way of further increasing the relevance of less-smooth substencils by adding a new term to the WENO-Z weights that uses information which is already available in its formula. The improved scheme attains much better resolution at the smooth parts of the solution, while keeping the same numerical stability of the original WENO-Z at shocks and discontinuities.

  12. 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.

  13. Multidimensional numerical scheme for resistive relativistic magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Komissarov, Serguei S.

    2007-12-01

    The paper describes a new upwind conservative numerical scheme for special relativistic resistive magnetohydrodynamics with scalar resistivity. The magnetic field is kept approximately divergence free and the divergence of the electric field is kept consistent with the electric charge distribution via the method of Generalized Lagrange Multiplier. The hyperbolic fluxes are computed using the Harten-Lax-van Leer (HLL) prescription and the source terms are accounted via the time-splitting technique. The results of test simulations show that the scheme can handle equally well both resistive current sheets and shock waves, and thus can be a useful tool for studying phenomena of relativistic astrophysics that involve both colliding supersonic flows and magnetic reconnection.

  14. 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.

  15. 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.

  16. 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.

  17. Secret Sharing Schemes and Advanced Encryption Standard

    DTIC Science & Technology

    2015-09-01

    without the selfless support and sacrifice of my wife, Sharon, who took the time to nurture our two children, Rianne and Rayden, during this one-year...polynomial to either a non-linear, or a monic polynomial form. Opportunities for future work of this nature are discussed in Chapter 6. Therefore, it...introduced variables that are protected by any secret sharing scheme cannot be solved using any algebraic transformation that is linear in nature , since

  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

    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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Satisfaction with the level and type of resource use of a health insurance scheme in Nigeria: health management organizations' perspectives.

    PubMed

    Mohammed, Shafiu; Souares, Aurelia; Lorenzo Bermejo, Justo; Babale, Sufiyan Muawiyyah; Sauerborn, Rainer; Dong, Hengjin

    2014-01-01

    Some developing countries have incorporated managed care elements into their national health insurance schemes. In practice, hybrid health management organizations (Hmos) are insurers who, bearing some resemblance to managed care in the USA, are vertically integrated in the scheme's revenue collection and pool and purchase healthcare services within a competitive framework. To date, few studies have focused on these organizations and their level of satisfaction with the scheme's optimal-resource-use (ORU) implementation. In Nigeria, the study site, Hmos were categorized on the basis of their satisfaction with ORU activities. One hundred forty-seven Hmo staff were randomly interviewed. The types of ORU domain categories were provider payment mechanism, administrative efficiency, benefit package inclusions and active monitoring mechanism. Bivariate analysis was used to determine differences among the Hmos' satisfaction with the various ORU domains. The Hmos' satisfaction with the health insurance scheme's ORU activities was 59.2% generally, and the associated factors were identified. According to the Hmos' perspectives related to the type of ORU, the fee-for-service payment method and regular inspection performed weakly. Hmos' limited satisfaction with the scheme's ORU raises concerns regarding ineffectiveness that may hinder implementation. To offset high risks in the scheme, it appears necessary for the regulatory agency to adapt and reform strategies of provider payment and active monitoring mechanisms according to stakeholder needs. Our findings further reveal that having Hmos evaluate ORU is useful for providing evidence-based information for policy making and regulatory utilization related to implementation of the health insurance scheme.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Activity.

    ERIC Educational Resources Information Center

    Clearing: Nature and Learning in the Pacific Northwest, 1984

    1984-01-01

    Presents three activities: (1) investigating succession in a schoolground; (2) investigating oak galls; and (3) making sun prints (photographs made without camera or darkroom). Each activity includes a list of materials needed and procedures used. (JN)

  1. 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.

  2. 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).

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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…

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Studying ignition schemes on European laser facilities

    NASA Astrophysics Data System (ADS)

    Jacquemot, S.; Amiranoff, F.; Baton, S. D.; Chanteloup, J. C.; Labaune, C.; Koenig, M.; Michel, D. T.; Perez, F.; Schlenvoigt, H. P.; Canaud, B.; Cherfils Clérouin, C.; Debras, G.; Depierreux, S.; Ebrardt, J.; Juraszek, D.; Lafitte, S.; Loiseau, P.; Miquel, J. L.; Philippe, F.; Rousseaux, C.; Blanchot, N.; Edwards, C. B.; Norreys, P.; Atzeni, S.; Schiavi, A.; Breil, J.; Feugeas, J. L.; Hallo, L.; Lafon, M.; Ribeyre, X.; Santos, J. J.; Schurtz, G.; Tikhonchuk, V.; Debayle, A.; Honrubia, J. J.; Temporal, M.; Batani, D.; Davies, J. R.; Fiuza, F.; Fonseca, R. A.; Silva, L. O.; Gizzi, L. A.; Koester, P.; Labate, L.; Badziak, J.; Klimo, O.

    2011-09-01

    Demonstrating ignition and net energy gain in the near future on MJ-class laser facilities will be a major step towards determining the feasibility of Inertial Fusion Energy (IFE), in Europe as in the United States. The current status of the French Laser MégaJoule (LMJ) programme, from the laser facility construction to the indirectly driven central ignition target design, is presented, as well as validating experimental campaigns, conducted, as part of this programme, on various laser facilities. However, the viability of the IFE approach strongly depends on our ability to address the salient questions related to efficiency of the target design and laser driver performances. In the overall framework of the European HiPER project, two alternative schemes both relying on decoupling target compression and fuel heating—fast ignition (FI) and shock ignition (SI)—are currently considered. After a brief presentation of the HiPER project's objectives, FI and SI target designs are discussed. Theoretical analysis and 2D simulations will help to understand the unresolved key issues of the two schemes. Finally, the on-going European experimental effort to demonstrate their viability on currently operated laser facilities is described.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Multi-resolution analysis for ENO schemes

    NASA Technical Reports Server (NTRS)

    Harten, Ami

    1993-01-01

    Given a function u(x) which is represented by its cell-averages in cells which are formed by some unstructured grid, we show how to decompose the function into various scales of variation. This is done by considering a set of nested grids in which the given grid is the finest, and identifying in each locality the coarsest grid in the set from which u(x) can be recovered to a prescribed accuracy. We apply this multi-resolution analysis to Essentially Non-oscillatory Schemes (ENO) schemes in order to reduce the number of numerical flux computations which is needed in order to advance the solution by one time-step. This is accomplished by decomposing the numerical solution at the beginning of each time-step into levels of resolution, and performing the computation in each locality at the appropriate coarser grid. We present an efficient algorithm for implementing this program in the one-dimensional case; this algorithm can be extended to the multi-dimensional case with cartesian grids.

  6. Privacy protection schemes for fingerprint recognition systems

    NASA Astrophysics Data System (ADS)

    Marasco, Emanuela; Cukic, Bojan

    2015-05-01

    The deployment of fingerprint recognition systems has always raised concerns related to personal privacy. A fingerprint is permanently associated with an individual and, generally, it cannot be reset if compromised in one application. Given that fingerprints are not a secret, potential misuses besides personal recognition represent privacy threats and may lead to public distrust. Privacy mechanisms control access to personal information and limit the likelihood of intrusions. In this paper, image- and feature-level schemes for privacy protection in fingerprint recognition systems are reviewed. Storing only key features of a biometric signature can reduce the likelihood of biometric data being used for unintended purposes. In biometric cryptosystems and biometric-based key release, the biometric component verifies the identity of the user, while the cryptographic key protects the communication channel. Transformation-based approaches only a transformed version of the original biometric signature is stored. Different applications can use different transforms. Matching is performed in the transformed domain which enable the preservation of low error rates. Since such templates do not reveal information about individuals, they are referred to as cancelable templates. A compromised template can be re-issued using a different transform. At image-level, de-identification schemes can remove identifiers disclosed for objectives unrelated to the original purpose, while permitting other authorized uses of personal information. Fingerprint images can be de-identified by, for example, mixing fingerprints or removing gender signature. In both cases, degradation of matching performance is minimized.

  7. A closure scheme for chemical master equations.

    PubMed

    Smadbeck, Patrick; Kaznessis, Yiannis N

    2013-08-27

    Probability reigns in biology, with random molecular events dictating the fate of individual organisms, and propelling populations of species through evolution. In principle, the master probability equation provides the most complete model of probabilistic behavior in biomolecular networks. In practice, master equations describing complex reaction networks have remained unsolved for over 70 years. This practical challenge is a reason why master equations, for all their potential, have not inspired biological discovery. Herein, we present a closure scheme that solves the master probability equation of networks of chemical or biochemical reactions. We cast the master equation in terms of ordinary differential equations that describe the time evolution of probability distribution moments. We postulate that a finite number of moments capture all of the necessary information, and compute the probability distribution and higher-order moments by maximizing the information entropy of the system. An accurate order closure is selected, and the dynamic evolution of molecular populations is simulated. Comparison with kinetic Monte Carlo simulations, which merely sample the probability distribution, demonstrates this closure scheme is accurate for several small reaction networks. The importance of this result notwithstanding, a most striking finding is that the steady state of stochastic reaction networks can now be readily computed in a single-step calculation, without the need to simulate the evolution of the probability distribution in time.

  8. A closure scheme for chemical master equations

    PubMed Central

    Smadbeck, Patrick; Kaznessis, Yiannis N.

    2013-01-01

    Probability reigns in biology, with random molecular events dictating the fate of individual organisms, and propelling populations of species through evolution. In principle, the master probability equation provides the most complete model of probabilistic behavior in biomolecular networks. In practice, master equations describing complex reaction networks have remained unsolved for over 70 years. This practical challenge is a reason why master equations, for all their potential, have not inspired biological discovery. Herein, we present a closure scheme that solves the master probability equation of networks of chemical or biochemical reactions. We cast the master equation in terms of ordinary differential equations that describe the time evolution of probability distribution moments. We postulate that a finite number of moments capture all of the necessary information, and compute the probability distribution and higher-order moments by maximizing the information entropy of the system. An accurate order closure is selected, and the dynamic evolution of molecular populations is simulated. Comparison with kinetic Monte Carlo simulations, which merely sample the probability distribution, demonstrates this closure scheme is accurate for several small reaction networks. The importance of this result notwithstanding, a most striking finding is that the steady state of stochastic reaction networks can now be readily computed in a single-step calculation, without the need to simulate the evolution of the probability distribution in time. PMID:23940327

  9. Quantum group signature scheme based on controlled quantum teleportation

    NASA Astrophysics Data System (ADS)

    Chen, F. L.; Han, Z. F.

    2016-11-01

    Group signature scheme is a method of allowing a member of a group to sign a message anonymously on behalf of the group. The group administrator is in charge of adding group members and has the ability to reveal the original signer in the event of disputes. Based on controlled quantum teleportation with three-particle entangled W states, we propose a new quantum group signature scheme with designated receiver. Security analysis proves that the proposed scheme possesses the characteristics of group signature and resists the usual attacks. Compared with previous proposed schemes, this scheme follows security definition of group signature fully and meets its basic requirements.

  10. Analysis of a Teacher's Pedagogical Arguments Using Toulmin's Model and Argumentation Schemes

    ERIC Educational Resources Information Center

    Metaxas, N.; Potari, D.; Zachariades, T.

    2016-01-01

    In this article, we elaborate methodologies to study the argumentation speech of a teacher involved in argumentative activities. The standard tool of analysis of teachers' argumentation concerning pedagogical matters is Toulmin's model. The theory of argumentation schemes offers an alternative perspective on the analysis of arguments. We propose…

  11. Exploring the Perceptions of Success in an Exercise Referral Scheme: A Mixed Method Investigation

    ERIC Educational Resources Information Center

    Mills, Hayley; Crone, Diane; James, David V. B.; Johnston, Lynne H.

    2012-01-01

    Background: Exercise referral schemes feature as one of the prevalent primary care physical activity interventions in the United Kingdom, without extensive understanding of how those involved in providing and participating view success. The present research explores and reveals the constituents of "success," through comparison,…

  12. Attracting Tomorrow's Engineers: An Evaluation of a Scheme to Enhance Recruitment into Engineering

    ERIC Educational Resources Information Center

    Smith, Nicholas; Monk, Martin

    2005-01-01

    This paper reports a survey of 16 to 17 year old students who took part in a school based project activity designed to motivate them to consider a career in engineering. The scheme can be considered a success in that an uppermost estimated figure of 19% more students were recruited to engineering undergraduate courses than might otherwise have…

  13. Patterns of Learning in the Accountancy Profession under an Output-Based Continuing Professional Development Scheme

    ERIC Educational Resources Information Center

    Lindsay, Hilary

    2012-01-01

    Since 2004, professional accountancy bodies in membership of the International Federation of Accountants (IFAC) have been required to adopt mandatory continuing professional development (CPD) schemes. This research explores the learning activities of members of the Institute of Chartered Accountants in England and Wales (ICAEW) which introduced an…

  14. Implicit Space-Time Conservation Element and Solution Element Schemes

    NASA Technical Reports Server (NTRS)

    Chang, Sin-Chung; Himansu, Ananda; Wang, Xiao-Yen

    1999-01-01

    Artificial numerical dissipation is in important issue in large Reynolds number computations. In such computations, the artificial dissipation inherent in traditional numerical schemes can overwhelm the physical dissipation and yield inaccurate results on meshes of practical size. In the present work, the space-time conservation element and solution element method is used to construct new and accurate implicit numerical schemes such that artificial numerical dissipation will not overwhelm physical dissipation. Specifically, these schemes have the property that numerical dissipation vanishes when the physical viscosity goes to zero. These new schemes therefore accurately model the physical dissipation even when it is extremely small. The new schemes presented are two highly accurate implicit solvers for a convection-diffusion equation. The two schemes become identical in the pure convection case, and in the pure diffusion case. The implicit schemes are applicable over the whole Reynolds number range, from purely diffusive equations to convection-dominated equations with very small viscosity. The stability and consistency of the schemes are analysed, and some numerical results are presented. It is shown that, in the inviscid case, the new schemes become explicit and their amplification factors are identical to those of the Leapfrog scheme. On the other hand, in the pure diffusion case, their principal amplification factor becomes the amplification factor of the Crank-Nicolson scheme.

  15. Spatial dimming scheme for optical OFDM based visible light communication.

    PubMed

    Yang, Yang; Zeng, Zhimin; Cheng, Julian; Guo, Caili

    2016-12-26

    A new dimming control scheme termed spatial dimming orthogonal frequency division multiplexing (SD-OFDM) is proposed for multiple-input and multiple output OFDM based visible light communication. The basic idea of SD-OFDM is that the illumination can be represented by the number of glared light emitting diodes (LEDs) in an LED lamp. As the biasing level of LEDs does not adjust to represent the required illumination level, the proposed scheme can significantly mitigate the clipping noise compared to analogue dimming schemes. Furthermore, unlike digital dimming schemes that control illumination levels by setting different duty cycles of pulse width modulation, the proposed scheme is always in the "on-state" for varied illumination levels. Both analytical and simulation results indicate that the proposed scheme is an efficient and feasible dimmable scheme.

  16. Quantum scheme for secret sharing based on local distinguishability

    NASA Astrophysics Data System (ADS)

    Rahaman, Ramij; Parker, Matthew G.

    2015-02-01

    In this paper, we analyze the (im)possibility of the exact distinguishability of orthogonal multipartite entangled states under restricted local operation and classical communication. Based on this local distinguishability analysis, we propose a quantum secret sharing scheme (which we call LOCC-QSS). Our LOCC-QSS scheme is quite general and cost efficient compared to other schemes. In our scheme, no joint quantum operation is needed to reconstruct the secret. We also present an interesting (2 ,n ) -threshold LOCC-QSS scheme, where any two cooperating players, one from each of two disjoint groups of players, can always reconstruct the secret. This LOCC-QSS scheme is quite uncommon, as most (k ,n ) -threshold quantum secret sharing schemes have the restriction k ≥⌈n/2 ⌉ .

  17. The sensitivity of polar ozone depletion to proposed geoengineering schemes.

    PubMed

    Tilmes, Simone; Müller, Rolf; Salawitch, Ross

    2008-05-30

    The large burden of sulfate aerosols injected into the stratosphere by the eruption of Mount Pinatubo in 1991 cooled Earth and enhanced the destruction of polar ozone in the subsequent few years. The continuous injection of sulfur into the stratosphere has been suggested as a "geoengineering" scheme to counteract global warming. We use an empirical relationship between ozone depletion and chlorine activation to estimate how this approach might influence polar ozone. An injection of sulfur large enough to compensate for surface warming caused by the doubling of atmospheric CO2 would strongly increase the extent of Arctic ozone depletion during the present century for cold winters and would cause a considerable delay, between 30 and 70 years, in the expected recovery of the Antarctic ozone hole.

  18. The smoothing transformer, a new concept in dc side harmonic reduction of HVdc schemes

    SciTech Connect

    Enright, W.; Arrillaga, J.; Wood, A.R.; Hidalgo, F.P.

    1996-10-01

    Direct connection schemes have been a subject of recent investigation, offering operational flexibility and substantial reductions in ac components. In these schemes the use of active dc filters has been suggested to replace the conventional tuned passive filter design. This paper presents the smoothing transformer as a new means for reducing dc harmonics at characteristic and non-characteristic frequencies using only passive components. A realistic smoothing transformer design is examined using the New Zealand HVdc system operating in the direct connection mode. The steady-state and transient performance of the smoothing transformer design is compared with that of the existing dc smoothing reactor and filter bank.

  19. Quantification of numerical diffusivity due to TVD schemes in the advection equation

    NASA Astrophysics Data System (ADS)

    Bidadi, Shreyas; Rani, Sarma L.

    2014-03-01

    In this study, the numerical diffusivity νnum inherent to the Roe-MUSCL scheme has been quantified for the scalar advection equation. The Roe-MUSCL scheme employed is a combination of: (1) the standard extension of the original Roe's formulation to the advection equation, and (2) van Leer's Monotone Upwind Scheme for Conservation Laws (MUSCL) technique that applies a linear variable reconstruction in a cell along with a scaled limiter function. An explicit expression is derived for the numerical diffusivity in terms of the limiter function, the distance between the cell centers on either side of a face, and the face-normal velocity. The numerical diffusivity formulation shows that a scaled limiter function is more appropriate for MUSCL in order to consistently recover the central-differenced flux at the maximum value of the limiter. The significance of the scaling factor is revealed when the Roe-MUSCL scheme, originally developed for 1-D scenarios, is applied to 2-D scalar advection problems. It is seen that without the scaling factor, the MUSCL scheme may not necessarily be monotonic in multi-dimensional scenarios. Numerical diffusivities of the minmod, superbee, van Leer and Barth-Jesperson TVD limiters were quantified for four problems: 1-D advection of a step function profile, and 2-D advection of step, sinusoidal, and double-step profiles. For all the cases, it is shown that the superbee scheme provides the lowest numerical diffusivity that is also most confined to the vicinity of the discontinuity. The minmod scheme is the most diffusive, as well as active in regions away from high gradients. As expected, the grid resolution study demonstrates that the magnitude and the spatial extent of the numerical diffusivity decrease with increasing resolution.

  20. Improved Timing Scheme for Spaceborne Precipitation Radar

    NASA Technical Reports Server (NTRS)

    Berkun, Andrew; Fischman, Mark

    2004-01-01

    An improved timing scheme has been conceived for operation of a scanning satellite-borne rain-measuring radar system. The scheme allows a real-time-generated solution, which is required for auto targeting. The current timing scheme used in radar satellites involves pre-computing a solution that allows the instrument to catch all transmitted pulses without transmitting and receiving at the same time. Satellite altitude requires many pulses in flight at any time, and the timing solution to prevent transmit and receive operations from colliding is usually found iteratively. The proposed satellite has a large number of scanning beams each with a different range to target and few pulses per beam. Furthermore, the satellite will be self-targeting, so the selection of which beams are used will change from sweep to sweep. The proposed timing solution guarantees no echo collisions, can be generated using simple FPGA-based hardware in real time, and can be mathematically shown to deliver the maximum number of pulses per second, given the timing constraints. The timing solution is computed every sweep, and consists of three phases: (1) a build-up phase, (2) a feedback phase, and (3) a build-down phase. Before the build-up phase can begin, the beams to be transmitted are sorted in numerical order. The numerical order of the beams is also the order from shortest range to longest range. Sorting the list guarantees no pulse collisions. The build-up phase begins by transmitting the first pulse from the first beam on the list. Transmission of this pulse starts a delay counter, which stores the beam number and the time delay to the beginning of the receive window for that beam. The timing generator waits just long enough to complete the transmit pulse plus one receive window, then sends out the second pulse. The second pulse starts a second delay counter, which stores its beam number and time delay. This process continues until an output from the first timer indicates there is less

  1. An efficient compression scheme for bitmap indices

    SciTech Connect

    Wu, Kesheng; Otoo, Ekow J.; Shoshani, Arie

    2004-04-13

    When using an out-of-core indexing method to answer a query, it is generally assumed that the I/O cost dominates the overall query response time. Because of this, most research on indexing methods concentrate on reducing the sizes of indices. For bitmap indices, compression has been used for this purpose. However, in most cases, operations on these compressed bitmaps, mostly bitwise logical operations such as AND, OR, and NOT, spend more time in CPU than in I/O. To speedup these operations, a number of specialized bitmap compression schemes have been developed; the best known of which is the byte-aligned bitmap code (BBC). They are usually faster in performing logical operations than the general purpose compression schemes, but, the time spent in CPU still dominates the total query response time. To reduce the query response time, we designed a CPU-friendly scheme named the word-aligned hybrid (WAH) code. In this paper, we prove that the sizes of WAH compressed bitmap indices are about two words per row for large range of attributes. This size is smaller than typical sizes of commonly used indices, such as a B-tree. Therefore, WAH compressed indices are not only appropriate for low cardinality attributes but also for high cardinality attributes.In the worst case, the time to operate on compressed bitmaps is proportional to the total size of the bitmaps involved. The total size of the bitmaps required to answer a query on one attribute is proportional to the number of hits. These indicate that WAH compressed bitmap indices are optimal. To verify their effectiveness, we generated bitmap indices for four different datasets and measured the response time of many range queries. Tests confirm that sizes of compressed bitmap indices are indeed smaller than B-tree indices, and query processing with WAH compressed indices is much faster than with BBC compressed indices, projection indices and B-tree indices. In addition, we also verified that the average query response time

  2. Replacing the bucket scheme of ECHAM6 with a five soil layer hydrology scheme

    NASA Astrophysics Data System (ADS)

    Hagemann, Stefan

    2010-05-01

    In climate research, the so-called bucket model has been widely spread where the soil water is represented by a single soil moisture reservoir, such as it is still the case in the current operational climate models of the Max Planck Institute for Meteorology (MPI-M), ECHAM6 and REMO. But in the transition of these climate models to comprehensive Earth system models, this single soil moisture layer is no longer sufficient. Here, biosphere processes must be coupled to the hydrological processes using bio-geochemical models. But these models usually need a vertical discrimination of the soil water storage. This was raised as a key issue for bio-geochemical model requirements at the MPI for Biogeochemistry and the MPI for Chemistry within the ENIGMA (Earth System Network of Integrated Modelling and Assessment) network. In addition, the higher vertical discrimination is also needed for the implementation of permafrost related processes, especially soil moisture melting and freezing, which is currently in preparation. Therefore, one objective is to achieve an improved representation of hydrological processes in the MPI-M Earth system models, especially of those that play an important role in the coupling to bio-geochemical processes. To this end, a five soil layer hydrology scheme has been implemented into the JSBACH scheme (the land surface component of ECHAM6) that is consistent with the five temperature layers already included in the ECHAM physics used in JSBACH and REMO. The new scheme will be presented, as well as results from validation simulations conducted with AMIP2 SST forcing at T31 and T63 resolution. The analysis of results will focus on differences between the simulations with and without (i.e. using the bucket scheme) the five soil layer hydrology scheme. It will be investigated why specific differences occur, and areas will be highlighted where the regional climate seems to be sensitive to the soil hydrology.

  3. The Dynamics of Some Iterative Implicit Schemes

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Sweby, P. K.

    1994-01-01

    The global asymptotic nonlinear behavior of some standard iterative procedures in solving nonlinear systems of algebraic equations arising from four implicit linear multistep methods (LMMs) in discretizing 2 x 2 systems of first-order autonomous nonlinear ordinary differential equations is analyzed using the theory of dynamical systems. With the aid of parallel Connection Machines (CM-2 and CM-5), the associated bifurcation diagrams as a function of the time step, and the complex behavior of the associated 'numerical basins of attraction' of these iterative implicit schemes are revealed and compared. Studies showed that all of the four implicit LMMs exhibit a drastic distortion and segmentation but less shrinkage of the basin of attraction of the true solution than standard explicit methods. The numerical basins of attraction of a noniterative implicit procedure mimic more closely the basins of attraction of the differential equations than the iterative implicit procedures for the four implicit LMMs.

  4. Efficient Conservative Reformulation Schemes for Lithium Intercalation

    SciTech Connect

    Urisanga, PC; Rife, D; De, S; Subramanian, VR

    2015-02-18

    Porous electrode theory coupled with transport and reaction mechanisms is a widely used technique to model Li-ion batteries employing an appropriate discretization or approximation for solid phase diffusion with electrode particles. One of the major difficulties in simulating Li-ion battery models is the need to account for solid phase diffusion in a second radial dimension r, which increases the computation time/cost to a great extent. Various methods that reduce the computational cost have been introduced to treat this phenomenon, but most of them do not guarantee mass conservation. The aim of this paper is to introduce an inherently mass conserving yet computationally efficient method for solid phase diffusion based on Lobatto III A quadrature. This paper also presents coupling of the new solid phase reformulation scheme with a macro-homogeneous porous electrode theory based pseudo 20 model for Li-ion battery. (C) The Author(s) 2015. Published by ECS. All rights reserved.

  5. Overlay caching scheme for overlay networks

    NASA Astrophysics Data System (ADS)

    Tran, Minh; Tavanapong, Wallapak

    2003-01-01

    Recent years have seen a tremendous growth of interests in streaming continuous media such as video over the Internet. This would create an enormous increase in the demand on various server and networking resources. To minimize service delays and to reduce loads placed on these resources, we propose an Overlay Caching Scheme (OCS) for overlay networks. OCS utilizes virtual cache structures to coordinate distributed overlay caching nodes along the delivery path between the server and the clients. OCS establishes and adapts these structures dynamically according to clients' locations and request patterns. Compared with existing video caching techniques, OCS offers better performances in terms of average service delays, server load, and network load in most cases in our study.

  6. The upgraded scheme of Hefei Light Source

    SciTech Connect

    Li Weimin; Xu Hongliang; Wang Lin; Feng Guangyao; Zhang Shancai; Hao Hao

    2010-06-23

    To enhance the performance of Hefei Light Source, which was designed and constructed two decades ago, an upgrade project would be carried out in the near future. The detail upgrade scheme was described in this paper. Firstly, the magnet lattice of storage ring should be reconstructed with 4 DBA cells, whose advantages are lower beam emittance and more straight section available for insertion devices. Secondly, the beam diagnostics, main power supply, transverse and longitudinal multi-bunch feedback, beam control and manipulation system would be upgrade to improve the beam orbit stability. Finally, the injection system of storage ring and injector, which is composed of electron linac and beam transfer line, would be updated in order to assure smooth beam accumulation process under new low emittance lattice. With above improvement, it is hopeful to increase the brilliance of Hefei Light Source by two orders approximately. After three-year upgrade project, the performance of HLS would meet the demands of advanced SR users.

  7. Multi-resolution analysis for ENO schemes

    NASA Technical Reports Server (NTRS)

    Harten, Ami

    1991-01-01

    Given an function, u(x), which is represented by its cell-averages in cells which are formed by some unstructured grid, we show how to decompose the function into various scales of variation. This is done by considering a set of nested grids in which the given grid is the finest, and identifying in each locality the coarsest grid in the set from which u(x) can be recovered to a prescribed accuracy. This multi-resolution analysis was applied to essentially non-oscillatory (ENO) schemes in order to advance the solution by one time-step. This is accomplished by decomposing the numerical solution at the beginning of each time-step into levels of resolution, and performing the computation in each locality at the appropriate coarser grid. An efficient algorithm for implementing this program in the 1-D case is presented; this algorithm can be extended to the multi-dimensional case with Cartesian grids.

  8. New scheme for braiding Majorana fermions

    PubMed Central

    Wu, Long-Hua; Liang, Qi-Feng; Hu, Xiao

    2014-01-01

    Non-Abelian statistics can be achieved by exchanging two vortices in topological superconductors with each grabbing a Majorana fermion (MF) as zero-energy quasi-particle at the cores. However, in experiments it is difficult to manipulate vortices. In the present work, we propose a way to braid MFs without moving vortices. The only operation required in the present scheme is to turn on and off local gate voltages, which liberates a MF from its original host vortex and transports it along the prepared track. We solve the time-dependent Bogoliubov–de Gennes equation numerically, and confirm that the MFs are protected provided the switching of gate voltages for exchanging MFs are adiabatic, which takes only several nano seconds given reasonable material parameters. By monitoring the time evolution of MF wave-functions, we show that non-Abelian statistics is achieved. PMID:27877725

  9. Doping Scheme of Semiconducting Atomic Chains

    NASA Technical Reports Server (NTRS)

    Toshishige, Yamada; Saini, Subhash (Technical Monitor)

    1998-01-01

    Atomic chains, precise structures of atomic scale created on an atomically regulated substrate surface, are candidates for future electronics. A doping scheme for intrinsic semiconducting Mg chains is considered. In order to suppress the unwanted Anderson localization and minimize the deformation of the original band shape, atomic modulation doping is considered, which is to place dopant atoms beside the chain periodically. Group I atoms are donors, and group VI or VII atoms are acceptors. As long as the lattice constant is long so that the s-p band crossing has not occurred, whether dopant atoms behave as donors or acceptors is closely related to the energy level alignment of isolated atomic levels. Band structures are calculated for Br-doped (p-type) and Cs-doped (n-type) Mg chains using the tight-binding theory with universal parameters, and it is shown that the band deformation is minimized and only the Fermi energy position is modified.

  10. A Scheme for Targeting Optical SETI Observations

    NASA Astrophysics Data System (ADS)

    Shostak, Seth

    2004-06-01

    In optical SETI (OSETI) experiments, it is generally assumed that signals will be deliberate, narrowly targeted beacons sent by extraterrestrial societies to large numbers of candidate star systems. If this is so, then it may be unrealistic to expect a high duty cycle for the received signal. Ergo, an advantage accrues to any OSETI scheme that realistically suggests where and when to search. In this paper, we elaborate a proposal (Castellano, Doyle, &McIntosh 2000) for selecting regions of sky for intensive optical SETI monitoring based on characteristics of our solar system that would be visible at great distance. This can enormously lessen the amount of sky that needs to be searched. In addition, this is an attractive approach for the transmitting society because it both increases the chances of reception and provides a large reduction in energy required. With good astrometric information, the transmitter need be no more powerful than an automobile tail light.

  11. Resident space object tracking using an interacting multiple model mixing scheme

    NASA Astrophysics Data System (ADS)

    Lam, Quang M.

    2014-06-01

    A multiple model estimation scheme is proposed to enhance the robustness of a resident space object (RSO) tracker subject to its maneuverability uncertainties (unplanned or unknown jet firing activities) and other system variations. The concept is based on the Interacting Multiple Model (IMM) estimation scheme. Within the IMM framework, two Extended Kalman Filter (EKF) models: (i) a 6 State (Position and Velocity of a constant orbiting RSO) EKF and (ii) a 9 state (Position, Velocity, and Acceleration of a maneuvering RSO) EKF are designed and implemented to achieve RSO maneuvering detection and enhanced tracking accuracy. The IMM estimation scheme is capable of providing enhanced state vector estimation accuracy and consistent prediction of the RSO maneuvering status, thus offering an attractive design feature for future Space Situational Awareness (SSA) missions. The design concept is illustrated using the Matlab/Based Simulation testing environment.

  12. Semi-Passive Chemical Oxidation Schemes for the Long-Term Treatment of Contaminants

    SciTech Connect

    Schwartz, Frank

    2004-12-01

    In situ chemical oxidation or ISCO schemes involve the addition of a chemical oxidant, such as potassium permanganate (KMnO4), which destroys chlorinated solvents like TCE in a straightforward reaction. Although ISCO is now regarded as a developing technology in an industrial sense, beyond active flushing schemes, there have been relatively limited investigations in how ISCO might be better used. Our previous study showed that KMnO4 flushing approaches often would be frustrated by the inability to control the delivery of the treatment fluid due to precipitation of low-permeability reaction by-product like MnO2 and other problems. It was therefore suggested that development of a new ISCO scheme that can provide both destruction efficiencies and plugging control would be required.

  13. WALK Community Grants Scheme: lessons learned in developing and administering a health promotion microgrants program.

    PubMed

    Caperchione, Cristina; Mummery, W Kerry; Joyner, Kelly

    2010-09-01

    The Women's Active Living Kits (WALK) Community Grant Scheme was a key component of a federally funded Australian initiative aimed at increasing local capacity to promote and engage priority women's groups in health-related physical activity. Under the program, community groups and organizations were provided with the opportunity to apply and receive small grants to support the development of women's walking groups with the aim of increasing physical activity participation levels in women, supporting innovative community ideas for increasing women's physical activity by improving social structures and environments, or both. This article describes the development and administration of the WALK Community Grant Scheme, outlines challenges and barriers encountered throughout the grant program process, and provides practical insights for replicating this initiative.

  14. Double-moment cloud microphysics scheme for the deep convection parameterization in the GFDL AM3

    NASA Astrophysics Data System (ADS)

    Belochitski, A.; Donner, L.

    2014-12-01

    A double-moment cloud microphysical scheme originally developed by Morrision and Gettelman (2008) for the stratiform clouds and later adopted for the deep convection by Song and Zhang (2011) has been implemented in to the Geophysical Fluid Dynamics Laboratory's atmospheric general circulation model AM3. The scheme treats cloud drop, cloud ice, rain, and snow number concentrations and mixing ratios as diagnostic variables and incorporates processes of autoconversion, self-collection, collection between hydrometeor species, sedimentation, ice nucleation, drop activation, homogeneous and heterogeneous freezing, and the Bergeron-Findeisen process. Such detailed representation of microphysical processes makes the scheme suitable for studying the interactions between aerosols and convection, as well as aerosols' indirect effects on clouds and their roles in climate change. The scheme is first tested in the single column version of the GFDL AM3 using forcing data obtained at the U.S. Department of Energy Atmospheric Radiation Measurment project's Southern Great Planes site. Scheme's impact on SCM simulations is discussed. As the next step, runs of the full atmospheric GCM incorporating the new parameterization are compared to the unmodified version of GFDL AM3. Global climatological fields and their variability are contrasted with those of the original version of the GCM. Impact on cloud radiative forcing and climate sensitivity is investigated.

  15. Assessment of various convective parametrisation schemes for warm season precipitation foracasts

    NASA Astrophysics Data System (ADS)

    Mazarakis, Nikos; Kotroni, Vassiliki; Lagouvardos, Konstantinos; Argyriou, Athanassios

    2010-05-01

    In the frame of the EU/FP6-funded FLASH project the sensitivity of numerical model quantitative precipitation forecasts to the choice of the convective parameterization scheme (CPS) has been examined for twenty selected cases characterized by intense convective activity and widespread precipitation over Greece, during the warm period of 2005 - 2007. The schemes are: Kain - Fritsch, Grell and Betts - Miller - Janjic. The simulated precipitation from the 8-km grid was verified against raingauge measurements and lightning data provided by the ZEUS long-range lightning detection system. The validation against both sources of data showed that among the three CPSs, the more consistent behavior in quantitative precipitation forecasting was obtained by the Kain - Fritsch scheme that provided the best statistical scores. Further various modifications of the Kain-Fritsch (KF) have been examined. The modifications include: (a) the maximization of the convective scheme precipitation efficiency, (b) the change of the convective time step, (c) the force of the convective scheme to produce more/less cloud material, (d) the alteration of the vertical profile of updraft mass flux detrainment.

  16. Improved Scheme for Modeling Mass Transfer between Fracture and Matrix Continua with Particle Tracking Method

    SciTech Connect

    L. Pan; Y. Seol; G. Bodvarsson

    2004-04-29

    The dual-continuum random-walk particle tracking approach is an attractive simulation method for simulating transport in a fractured porous medium. In order to be truly successful for such a model, however, the key issue is to properly simulate the mass transfer between the fracture and matrix continua. In a recent paper, Pan and Bodvarsson (2002) proposed an improved scheme for simulating fracture-matrix mass transfer, by introducing the concept of activity range into the calculation of fracture-matrix particle-transfer probability. By comparing with analytical solutions, they showed that their scheme successfully captured the transient diffusion depth into the matrix without any additional subgrid (matrix) cells. This technical note presents an expansion of their scheme to cases in which significant water flow through the fracture-matrix interface exists. The dual-continuum particle tracker with this new scheme was found to be as accurate as a numerical model using a more detailed grid. The improved scheme can be readily incorporated into the existing particle-tracking code, while still maintaining the advantage of needing no additional matrix cells to capture transient features of particle penetration into the matrix.

  17. A fuzzy robust control scheme for vibration suppression of a nonlinear electromagnetic-actuated flexible system

    NASA Astrophysics Data System (ADS)

    Tavakolpour-Saleh, A. R.; Haddad, M. A.

    2017-03-01

    In this paper, a novel robust vibration control scheme, namely, one degree-of-freedom fuzzy active force control (1DOF-FAFC) is applied to a nonlinear electromagnetic-actuated flexible plate system. First, the flexible plate with clamped-free-clamped-free (CFCF) boundary conditions is modeled and simulated. Then, the validity of the simulation platform is evaluated through experiment. A nonlinear electromagnetic actuator is developed and experimentally modeled through a parametric system identification scheme. Next, the obtained nonlinear model of the actuator is applied to the simulation platform and performance of the proposed control technique in suppressing unwanted vibrations is investigated via simulation. A fuzzy controller is applied to the robust 1DOF control scheme to tune the controller gain using acceleration feedback. Consequently, an intelligent self-tuning vibration control strategy based on an inexpensive acceleration sensor is proposed in the paper. Furthermore, it is demonstrated that the proposed acceleration-based control technique owns the benefits of the conventional velocity feedback controllers. Finally, an experimental rig is developed to investigate the effectiveness of the 1DOF-FAFC scheme. It is found that the first, second, and third resonant modes of the flexible system are attenuated up to 74%, 81%, and 90% respectively through which the effectiveness of the proposed control scheme is affirmed.

  18. On Convergence of High Order Shock Capturing Difference Schemes

    NASA Astrophysics Data System (ADS)

    Ostapenko, V.

    2010-11-01

    A convergence of high order shock capturing difference schemes is analyzed. Notions of weak finite difference approximations which conserve a sense on discontinuous solutions are introduced. Necessary and sufficient conditions of these approximations are obtained. It is shown that among the explicit two-layer in time conservative difference schemes there are no schemes which can have high order of weak approximation. A compact scheme of the same third order of classical and weak approximations is constructed. There is demonstrated an advantage of this scheme in comparison to TVD scheme at shock-capturing computations. A difference approximation of ɛ Rankine-Hugoniot (RH) conditions is investigated. It is shown that TVD type schemes (in contrast to non-TVD schemes, whose numerical fluxes are smooth enough) can approximate ɛ RH-conditions at most with the first order. Given examples show that non-TVD schemes (in contrast to TVD schemes) can have the second order of integral convergence through the smearing shocks and as a result can conserve a higher accuracy in the post shock regions.

  19. An improved anonymous authentication scheme for telecare medical information systems.

    PubMed

    Wen, Fengtong; Guo, Dianli

    2014-05-01

    Telecare medical information system (TMIS) constructs an efficient and convenient connection between patients and the medical server. The patients can enjoy medical services through public networks, and hence the protection of patients' privacy is very significant. Very recently, Wu et al. identified Jiang et al.'s authentication scheme had some security drawbacks and proposed an enhanced authentication scheme for TMIS. However, we analyze Wu et al.'s scheme and show that their scheme suffers from server spoofing attack, off-line password guessing attack, impersonation attack. Moreover, Wu et al.'s scheme fails to preserve the claimed patient anonymity and its password change phase is unfriendly and inefficient. Thereby, we present a novel anonymous authentication scheme for telecare medical information systems to eliminate the aforementioned faults. Besides, We demonstrate the completeness of the proposed scheme through the BAN logic. Furthermore, the security of our proposed scheme is proven through Bellare and Rogaways model. Compared with the related existing schemes, our scheme is more secure.

  20. Quantum Attack-Resistent Certificateless Multi-Receiver Signcryption Scheme

    PubMed Central

    Li, Huixian; Chen, Xubao; Pang, Liaojun; Shi, Weisong

    2013-01-01

    The existing certificateless signcryption schemes were designed mainly based on the traditional public key cryptography, in which the security relies on the hard problems, such as factor decomposition and discrete logarithm. However, these problems will be easily solved by the quantum computing. So the existing certificateless signcryption schemes are vulnerable to the quantum attack. Multivariate public key cryptography (MPKC), which can resist the quantum attack, is one of the alternative solutions to guarantee the security of communications in the post-quantum age. Motivated by these concerns, we proposed a new construction of the certificateless multi-receiver signcryption scheme (CLMSC) based on MPKC. The new scheme inherits the security of MPKC, which can withstand the quantum attack. Multivariate quadratic polynomial operations, which have lower computation complexity than bilinear pairing operations, are employed in signcrypting a message for a certain number of receivers in our scheme. Security analysis shows that our scheme is a secure MPKC-based scheme. We proved its security under the hardness of the Multivariate Quadratic (MQ) problem and its unforgeability under the Isomorphism of Polynomials (IP) assumption in the random oracle model. The analysis results show that our scheme also has the security properties of non-repudiation, perfect forward secrecy, perfect backward secrecy and public verifiability. Compared with the existing schemes in terms of computation complexity and ciphertext length, our scheme is more efficient, which makes it suitable for terminals with low computation capacity like smart cards. PMID:23967037

  1. Quantum attack-resistent certificateless multi-receiver signcryption scheme.

    PubMed

    Li, Huixian; Chen, Xubao; Pang, Liaojun; Shi, Weisong

    2013-01-01

    The existing certificateless signcryption schemes were designed mainly based on the traditional public key cryptography, in which the security relies on the hard problems, such as factor decomposition and discrete logarithm. However, these problems will be easily solved by the quantum computing. So the existing certificateless signcryption schemes are vulnerable to the quantum attack. Multivariate public key cryptography (MPKC), which can resist the quantum attack, is one of the alternative solutions to guarantee the security of communications in the post-quantum age. Motivated by these concerns, we proposed a new construction of the certificateless multi-receiver signcryption scheme (CLMSC) based on MPKC. The new scheme inherits the security of MPKC, which can withstand the quantum attack. Multivariate quadratic polynomial operations, which have lower computation complexity than bilinear pairing operations, are employed in signcrypting a message for a certain number of receivers in our scheme. Security analysis shows that our scheme is a secure MPKC-based scheme. We proved its security under the hardness of the Multivariate Quadratic (MQ) problem and its unforgeability under the Isomorphism of Polynomials (IP) assumption in the random oracle model. The analysis results show that our scheme also has the security properties of non-repudiation, perfect forward secrecy, perfect backward secrecy and public verifiability. Compared with the existing schemes in terms of computation complexity and ciphertext length, our scheme is more efficient, which makes it suitable for terminals with low computation capacity like smart cards.

  2. Efficient and Anonymous Authentication Scheme for Wireless Body Area Networks.

    PubMed

    Wu, Libing; Zhang, Yubo; Li, Li; Shen, Jian

    2016-06-01

    As a significant part of the Internet of Things (IoT), Wireless Body Area Network (WBAN) has attract much attention in this years. In WBANs, sensors placed in or around the human body collect the sensitive data of the body and transmit it through an open wireless channel in which the messages may be intercepted, modified, etc. Recently, Wang et al. presented a new anonymous authentication scheme for WBANs and claimed that their scheme can solve the security problems in the previous schemes. Unfortunately, we demonstrate that their scheme cannot withstand impersonation attack. Either an adversary or a malicious legal client could impersonate another legal client to the application provider. In this paper, we give the detailed weakness analysis of Wang et al.'s scheme at first. Then we present a novel anonymous authentication scheme for WBANs and prove that it's secure under a random oracle model. At last, we demonstrate that our presented anonymous authentication scheme for WBANs is more suitable for practical application than Wang et al.'s scheme due to better security and performance. Compared with Wang et al.'s scheme, the computation cost of our scheme in WBANs has reduced by about 31.58%.

  3. 49 CFR 393.79 - Windshield defrosting and defogging systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... bus, truck, and truck-tractor manufactured on or after December 25, 1968, must have a windshield... manufacture. (b) Vehicles manufactured before December 25, 1968. Each bus, truck, and truck-tractor shall...

  4. Self-defrosting recuperative air-to-air heat exchanger

    DOEpatents

    Drake, Richard L.

    1993-01-01

    A heat exchanger includes a stationary spirally or concentrically wound heat exchanger core with rotating baffles on upper and lower ends thereof. The rotating baffles include rotating inlets and outlets which are in communication with respective fixed inlets and outlets via annuli. The rotation of the baffles causes a concurrent rotation of the temperature distribution within the stationary exchanger core, thereby preventing frost build-up in some applications and preventing the formation of hot spots in other applications.

  5. EXPERIMENTAL INVESTIGATION OF DEFROST USING WARM LIQUID REFRIGERANT

    EPA Science Inventory

    This paper reports the results from laboratory tests of a low-temperature supermarket refrigeration system with two open and two reach-in display cases. Tests were performed at condensing temperatures ranging from 10 to 40 C and at an evaporating temperature of -34 C. The perfo...

  6. Self-defrosting recuperative air-to-air heat exchanger

    DOEpatents

    Drake, R.L.

    1993-12-28

    A heat exchanger is described which includes a stationary spirally or concentrically wound heat exchanger core with rotating baffles on upper and lower ends thereof. The rotating baffles include rotating inlets and outlets which are in communication with respective fixed inlets and outlets via annuli. The rotation of the baffles causes a concurrent rotation of the temperature distribution within the stationary exchanger core, thereby preventing frost build-up in some applications and preventing the formation of hot spots in other applications. 3 figures.

  7. Defrosting Polar Dunes--Changes Over a 26-Day Period

    NASA Technical Reports Server (NTRS)

    1999-01-01

    As the retreat of the south polar winter frost cap became visible in June 1999, high resolution images from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) began to show dark spots forming on the surfaces of frost-covered sand dunes. Immediately, the MOC science team began to plan to observe several dune fields more than once, should that opportunity arise, so that the evolution of these dark spots could be documented and studied. Such work will eventually lead to abetter understanding of how the martian polar caps retreat as winter ends and spring unfolds in each hemisphere.

    MGS is in a polar orbit, which means that, unlike many other places on Mars, the spacecraft has more opportunities to take pictures of the same place. Dune fields near 87o latitude can be repeatedly viewed; dunes near the equator are not likely to be photographed more than once during the entire MGS mission.

    The pictures presented here show changes on a set of nearly pear-shaped sand dunes located on the floor of an unnamed crater at 59oS, 353oW. The picture on the left shows the dunes as they appeared on June 19, 1999, the picture on the right shows the same dunes on July 15, 1999. The dark spots in the June 19picture--indicating areas where frost has sublimed away--became larger by July 15th. In addition, new spots had appeared as of mid-July. If possible, these dunes will be photographed by MOC again in mid-August and each month until the frost is gone.

    The pictures shown in (B) (above) are expanded views of portions of the pictures in (A). The 200 meter scale bar equals 656 feet; the 100 meter bar is 328 feet (109 yards) long. All images are illuminated from the upper left; north is toward the upper right.

    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.

  8. Activities.

    ERIC Educational Resources Information Center

    Bippert, Judy

    1993-01-01

    Presents activities designed to give students an opportunity to solve concrete problems involving spatial relationships and logical thinking utilizing hands-on manipulatives. Provides teacher instructions and four reproducible worksheets. (MDH)

  9. Variationally consistent discretization schemes and numerical algorithms for contact problems

    NASA Astrophysics Data System (ADS)

    Wohlmuth, Barbara

    We consider variationally consistent discretization schemes for mechanical contact problems. Most of the results can also be applied to other variational inequalities, such as those for phase transition problems in porous media, for plasticity or for option pricing applications from finance. The starting point is to weakly incorporate the constraint into the setting and to reformulate the inequality in the displacement in terms of a saddle-point problem. Here, the Lagrange multiplier represents the surface forces, and the constraints are restricted to the boundary of the simulation domain. Having a uniform inf-sup bound, one can then establish optimal low-order a priori convergence rates for the discretization error in the primal and dual variables. In addition to the abstract framework of linear saddle-point theory, complementarity terms have to be taken into account. The resulting inequality system is solved by rewriting it equivalently by means of the non-linear complementarity function as a system of equations. Although it is not differentiable in the classical sense, semi-smooth Newton methods, yielding super-linear convergence rates, can be applied and easily implemented in terms of a primal-dual active set strategy. Quite often the solution of contact problems has a low regularity, and the efficiency of the approach can be improved by using adaptive refinement techniques. Different standard types, such as residual- and equilibrated-based a posteriori error estimators, can be designed based on the interpretation of the dual variable as Neumann boundary condition. For the fully dynamic setting it is of interest to apply energy-preserving time-integration schemes. However, the differential algebraic character of the system can result in high oscillations if standard methods are applied. A possible remedy is to modify the fully discretized system by a local redistribution of the mass. Numerical results in two and three dimensions illustrate the wide range of

  10. An Efficient Remote Authentication Scheme for Wireless Body Area Network.

    PubMed

    Omala, Anyembe Andrew; Kibiwott, Kittur P; Li, Fagen

    2017-02-01

    Wireless body area network (WBAN) provide a mechanism of transmitting a persons physiological data to application providers e.g. hospital. Given the limited range of connectivity associated with WBAN, an intermediate portable device e.g. smartphone, placed within WBAN's connectivity, forwards the data to a remote server. This data, if not protected from an unauthorized access and modification may be lead to poor diagnosis. In order to ensure security and privacy between WBAN and a server at the application provider, several authentication schemes have been proposed. Recently, Wang and Zhang proposed an authentication scheme for WBAN using bilinear pairing. However, in their scheme, an application provider could easily impersonate a client. In order to overcome this weakness, we propose an efficient remote authentication scheme for WBAN. In terms of performance, our scheme can not only provide a malicious insider security, but also reduce running time of WBAN (client) by 51 % as compared to Wang and Zhang scheme.

  11. A novel quantum group signature scheme without using entangled states

    NASA Astrophysics Data System (ADS)

    Xu, Guang-Bao; Zhang, Ke-Jia

    2015-07-01

    In this paper, we propose a novel quantum group signature scheme. It can make the signer sign a message on behalf of the group without the help of group manager (the arbitrator), which is different from the previous schemes. In addition, a signature can be verified again when its signer disavows she has ever generated it. We analyze the validity and the security of the proposed signature scheme. Moreover, we discuss the advantages and the disadvantages of the new scheme and the existing ones. The results show that our scheme satisfies all the characteristics of a group signature and has more advantages than the previous ones. Like its classic counterpart, our scheme can be used in many application scenarios, such as e-government and e-business.

  12. A generalized well management scheme for reservoir simulation

    SciTech Connect

    Fang, W.Y.; Lo, K.K.

    1995-12-31

    A new generalized well management scheme has been formulated to maximize oil production under multiple facility constraints. The scheme integrates reserve performance, wellbore hydraulics, surface facility constraints and lift-gas allocation o maximize oil production. It predicts well performance based on up-to-date hydraulics and reservoir conditions. The scheme has been implemented in a black oil simulator by using Separable programming and Simplex algorithm. This production optimization scheme has been applied to two full-field models. The oil production of these two full-field models is limited by water, gas and liquid haling limits at both field- and flow station-levels. The gas production is limited by injectivity as well as gas handling limits. For a 12-year production forecast on Field A, the new scheme increased oil production by 3 to 9%. For a 12-year production forecast on field B, the new scheme increased oil production by 7 to 9%.

  13. Call Admission Control Scheme Based on Statistical Information

    NASA Astrophysics Data System (ADS)

    Fujiwara, Takayuki; Oki, Eiji; Shiomoto, Kohei

    A call admission control (CAC) scheme based on statistical information is proposed, called the statistical CAC scheme. A conventional scheme needs to manage session information for each link to update the residual bandwidth of a network in real time. This scheme has a scalability problem in terms of network size. The statistical CAC rejects session setup requests in accordance to a pre-computed ratio, called the rejection ratio. The rejection ratio is computed by using statistical information about the bandwidth requested for each link so that the congestion probability is less than an upper bound specified by a network operator. The statistical CAC is more scalable in terms of network size than the conventional scheme because it does not need to keep accommodated session state information. Numerical results show that the statistical CAC, even without exact session state information, only slightly degrades network utilization compared with the conventional scheme.

  14. Robust anonymous authentication scheme for telecare medical information systems.

    PubMed

    Xie, Qi; Zhang, Jun; Dong, Na

    2013-04-01

    Patient can obtain sorts of health-care delivery services via Telecare Medical Information Systems (TMIS). Authentication, security, patient's privacy protection and data confidentiality are important for patient or doctor accessing to Electronic Medical Records (EMR). In 2012, Chen et al. showed that Khan et al.'s dynamic ID-based authentication scheme has some weaknesses and proposed an improved scheme, and they claimed that their scheme is more suitable for TMIS. However, we show that Chen et al.'s scheme also has some weaknesses. In particular, Chen et al.'s scheme does not provide user's privacy protection and perfect forward secrecy, is vulnerable to off-line password guessing attack and impersonation attack once user's smart card is compromised. Further, we propose a secure anonymity authentication scheme to overcome their weaknesses even an adversary can know all information stored in smart card.

  15. An improved authentication scheme for telecare medicine information systems.

    PubMed

    Wei, Jianghong; Hu, Xuexian; Liu, Wenfen

    2012-12-01

    The telecare medicine information system enables or supports health-care delivery services. In order to safeguard patients' privacy, such as telephone number, medical record number, health information, etc., a secure authentication scheme will thus be in demand. Recently, Wu et al. proposed a smart card based password authentication scheme for the telecare medicine information system. Later, He et al. pointed out that Wu et al.'s scheme could not resist impersonation attacks and insider attacks, and then presented a new scheme. In this paper, we show that both of them fail to achieve two-factor authentication as smart card based password authentication schemes should achieve. We also propose an improved authentication scheme for the telecare medicine information system, and demonstrate that the improved one satisfies the security requirements of two-factor authentication and is also efficient.

  16. Efficient Unrestricted Identity-Based Aggregate Signature Scheme

    PubMed Central

    Yuan, Yumin; Zhan, Qian; Huang, Hua

    2014-01-01

    An aggregate signature scheme allows anyone to compress multiple individual signatures from various users into a single compact signature. The main objective of such a scheme is to reduce the costs on storage, communication and computation. However, among existing aggregate signature schemes in the identity-based setting, some of them fail to achieve constant-length aggregate signature or require a large amount of pairing operations which grows linearly with the number of signers, while others have some limitations on the aggregated signatures. The main challenge in building efficient aggregate signature scheme is to compress signatures into a compact, constant-length signature without any restriction. To address the above drawbacks, by using the bilinear pairings, we propose an efficient unrestricted identity-based aggregate signature. Our scheme achieves both full aggregation and constant pairing computation. We prove that our scheme has existential unforgeability under the computational Diffie-Hellman assumption. PMID:25329777

  17. Efficient unrestricted identity-based aggregate signature scheme.

    PubMed

    Yuan, Yumin; Zhan, Qian; Huang, Hua

    2014-01-01

    An aggregate signature scheme allows anyone to compress multiple individual signatures from various users into a single compact signature. The main objective of such a scheme is to reduce the costs on storage, communication and computation. However, among existing aggregate signature schemes in the identity-based setting, some of them fail to achieve constant-length aggregate signature or require a large amount of pairing operations which grows linearly with the number of signers, while others have some limitations on the aggregated signatures. The main challenge in building efficient aggregate signature scheme is to compress signatures into a compact, constant-length signature without any restriction. To address the above drawbacks, by using the bilinear pairings, we propose an efficient unrestricted identity-based aggregate signature. Our scheme achieves both full aggregation and constant pairing computation. We prove that our scheme has existential unforgeability under the computational Diffie-Hellman assumption.

  18. Copyright protection scheme based on chaos and secret sharing techniques

    NASA Astrophysics Data System (ADS)

    Lou, Der-Chyuan; Shieh, Jieh-Ming; Tso, Hao-Kuan

    2005-11-01

    A copyright protection scheme based on chaos and secret sharing techniques is proposed. Instead of modifying the original image to embed a watermark in it, the proposed scheme extracts a feature from the image first. Then, the extracted feature and the watermark are scrambled by a chaos technique. Finally, the secret sharing technique is used to construct a shadow image. The watermark can be retrieved by performing an XOR operation between the shadow images. The proposed scheme has the following advantages. Firstly, the watermark retrieval does not need the original image. Secondly, the scheme does not need to modify the original image for embedding the watermark. Thirdly, compared with several schemes, the scheme is secure and robust in resisting various attacks.

  19. Effects of sparse sampling schemes on image quality in low-dose CT

    SciTech Connect

    Abbas, Sajid; Lee, Taewon; Cho, Seungryong; Shin, Sukyoung; Lee, Rena

    2013-11-15

    Purpose: Various scanning methods and image reconstruction algorithms are actively investigated for low-dose computed tomography (CT) that can potentially reduce a health-risk related to radiation dose. Particularly, compressive-sensing (CS) based algorithms have been successfully developed for reconstructing images from sparsely sampled data. Although these algorithms have shown promises in low-dose CT, it has not been studied how sparse sampling schemes affect image quality in CS-based image reconstruction. In this work, the authors present several sparse-sampling schemes for low-dose CT, quantitatively analyze their data property, and compare effects of the sampling schemes on the image quality.Methods: Data properties of several sampling schemes are analyzed with respect to the CS-based image reconstruction using two measures: sampling density and data incoherence. The authors present five different sparse sampling schemes, and simulated those schemes to achieve a targeted dose reduction. Dose reduction factors of about 75% and 87.5%, compared to a conventional scan, were tested. A fully sampled circular cone-beam CT data set was used as a reference, and sparse sampling has been realized numerically based on the CBCT data.Results: It is found that both sampling density and data incoherence affect the image quality in the CS-based reconstruction. Among the sampling schemes the authors investigated, the sparse-view, many-view undersampling (MVUS)-fine, and MVUS-moving cases have shown promising results. These sampling schemes produced images with similar image quality compared to the reference image and their structure similarity index values were higher than 0.92 in the mouse head scan with 75% dose reduction.Conclusions: The authors found that in CS-based image reconstructions both sampling density and data incoherence affect the image quality, and suggest that a sampling scheme should be devised and optimized by use of these indicators. With this strategic

  20. Multilevel programmable logic array schemes for microprogrammed automata

    SciTech Connect

    Barkalov, A.A.

    1995-03-01

    Programmable logic arrays (PLAs) provide an efficient tool for implementation of logic schemes of microprogrammed automata (MPA). The number of PLAs in the MPA logic scheme can be minimized by increasing the number of levels. In this paper, we analyze the structures of multilevel schemes of Mealy automata, propose a number of new structures, consider the corresponding correctness conditions, and examine some problems that must be solved in order to satisfy these conditions.

  1. Scheme for atomic-state teleportation between two bad cavities

    SciTech Connect

    Zheng Shibiao; Guo Guangcan

    2006-03-15

    A scheme is presented for the long-distance teleportation of an unknown atomic state between two separated cavities. Our scheme works in the regime where the atom-cavity coupling strength is smaller than the cavity decay rate. Thus the requirement on the quality factor of the cavities is greatly relaxed. Furthermore, the fidelity of our scheme is not affected by the detection inefficiency and atomic decay. These advantages are important in view of experiments.

  2. An Improved Chaotic Masking Scheme via System-Alternating

    NASA Astrophysics Data System (ADS)

    Wang, Xing-Yuan; Xu, Bing; Ma, Yutian

    2013-10-01

    Aiming at the drawbacks of the chaotic masking scheme, this paper optimizes this conventional scheme by using improved state observer method and system-alternating method, proposes a new secure communication scheme which can improve these drawbacks of chaotic method: (1) Restriction that the power of useful signal must be smaller than that of chaotic signal. (2) Low security. In addition, the model of this whole communication system is constructed under the system simulation environment of Simulink.

  3. Convenient total variation diminishing conditions for nonlinear difference schemes

    NASA Technical Reports Server (NTRS)

    Tadmor, Eitan

    1986-01-01

    Convenient conditions for nonlinear difference schemes to be total-variation diminishing (TVD) are reviewed. It is shown that such schemes share the TVD property, provided their numerical fluxes meet a certain positivity condition at extrema values but can be arbitrary otherwise. The conditions are invariant under different incremental representations of the nonlinear schemes, and thus provide a simplified generalization of the TVD conditions due to Harten and others.

  4. New RSA-Based (Selectively) Convertible Undeniable Signature Schemes

    NASA Astrophysics Data System (ADS)

    Phong, Le Trieu; Kurosawa, Kaoru; Ogata, Wakaha

    In this paper, we design and analyze some new and practical (selectively) convertible undeniable signature (SCUS) schemes in both random oracle and standard model, which enjoy several merits over existing schemes in the literature. In particular, we design the first practical RSA-based SCUS schemes secure in the standard model. On the path, we also introduce two moduli RSA assumptions, including the strong twin RSA assumption, which is the RSA symmetry of the strong twin Diffie-Hellman assumption (Eurocrypt'08).

  5. A comparison of SPH schemes for the compressible Euler equations

    NASA Astrophysics Data System (ADS)

    Puri, Kunal; Ramachandran, Prabhu

    2014-01-01

    We review the current state-of-the-art Smoothed Particle Hydrodynamics (SPH) schemes for the compressible Euler equations. We identify three prototypical schemes and apply them to a suite of test problems in one and two dimensions. The schemes are in order, standard SPH with an adaptive density kernel estimation (ADKE) technique introduced Sigalotti et al. (2008) [44], the variational SPH formulation of Price (2012) [33] (referred herein as the MPM scheme) and the Godunov type SPH (GSPH) scheme of Inutsuka (2002) [12]. The tests investigate the accuracy of the inviscid discretizations, shock capturing ability and the particle settling behavior. The schemes are found to produce nearly identical results for the 1D shock tube problems with the MPM and GSPH schemes being the most robust. The ADKE scheme requires parameter values which must be tuned to the problem at hand. We propose an addition of an artificial heating term to the GSPH scheme to eliminate unphysical spikes in the thermal energy at the contact discontinuity. The resulting modification is simple and can be readily incorporated in existing codes. In two dimensions, the differences between the schemes is more evident with the quality of results determined by the particle distribution. In particular, the ADKE scheme shows signs of particle clumping and irregular motion for the 2D strong shock and Sedov point explosion tests. The noise in particle data is linked with the particle distribution which remains regular for the Hamiltonian formulations (MPM and GSPH) and becomes irregular for the ADKE scheme. In the interest of reproducibility, we make available our implementation of the algorithms and test problems discussed in this work.

  6. Analysis of Plasma Communication Schemes for Hypersonic Vehicles: Final Report

    DTIC Science & Technology

    2009-02-01

    the ReComm scheme for communications through the plasma sheath surrounding a hypersonic vehicle during re-entry. We demonstrate that the time...physical processes of the ReComm scheme for communications through the plasma sheath surrounding a hypersonic vehicle during re-entry. The ReComm scheme...relation is derived to estimate the plasma heating in the sheath due to plasma waves excited by the antenna. Contents I. Introduction 4 II. Electron

  7. Innovative resettlement schemes planned for the Numata Dam project

    NASA Astrophysics Data System (ADS)

    Nakayama, Mikiyasu

    2003-10-01

    The Numata Dam, planned for the Tone River basin of Gunma Prefecture, was the largest dam construction project ever considered in Japan. This dam construction project, however, did not materialize. The proposal for the Numata Dam was first launched in 1959, at a time when the Tokyo Metropolitan area was mushrooming, both in population and industrial activity. The Numata Dam was supposed to be a prioritized dam construction project to alleviate the then anticipated water shortage in the Tokyo Metropolitan area. The Numata Dam plan experienced fierce opposition from those who would have been obliged to resettle, whereas those in Tokyo and the surrounding metropolitan area welcomed the plan. The major concern of the planned Numata Dam was the number of resettlers, which was then estimated to be around 3000 families. The resettlement plan developed for the Numata Dam included some innovative concepts, which may be applicable even today, for dam construction projects in the developing world. The plan included such ideas as (a) having resettlers share existing farmland with the present owners provided improvements were made to increase productivity, (b) paying rent to resettlers, and (c) establishing the Tone River Development Agency. After more than a decade of debate, both at national and local levels, the Numata Dam project was finally discarded through a decision of the Prime Minister in 1972. The resettlement schemes elaborated for the Numata Dam still appear to be innovative. Such schemes may be applied to projects in the developing world, in particular, in nations that are about to take off with economic development. Copyright

  8. Preliminary Characterization and Classification Scheme for Tectonic Structures on Enceladus

    NASA Astrophysics Data System (ADS)

    Nahm, A.; Kattenhorn, S. A.

    2013-12-01

    The ice shell of Enceladus has experienced widespread and diverse tectonic deformation. Its leading and trailing hemispheres are pervasively fractured and these are separated by older cratered terrains on the sub- and anti-Saturnian hemispheres that exhibit relatively little tectonic deformation. The south polar terrain (SPT) is tectonically complex, geologically active, and is separated from the rest of Enceladus by the south polar dichotomy. The diversity of structures visible on the surface attests to a complicated and perhaps long-lived tectonic history. Currently, no fundamental classification scheme based on formation mechanisms exists for the tectonic structures on Enceladus, as does for Europa, which limits analysis and discussion of tectonic structures and the regional and global tectonic history. Characterization and classification of structures based on their formation mechanisms allows for the stress states (orientation, magnitude, and sense) responsible for their formation to be inferred. Thus, characterizing and classifying structures on Enceladus is a major first step in understanding its tectonic history. Here, we present a preliminary global classification scheme for tectonic structures on Enceladus. The basemap used for our preliminary structure classification was the global Imaging Science Subsystem (ISS) mosaic obtained from Ciclops (110 mpp; http://www.ciclops.org/view/7590/Map_of_Enceladus_-_December_2011?js=1). The structures observed on the surface have been divided into fifteen classes based on morphology. These classes represent the diversity of structure morphology on Enceladus and include the 'tiger stripes' in the SPT, the arcuate ridges that make up the south polar dichotomy, wide fracture complexes, several classes of narrow fractures, curvilinear subparallel fractures, rifts that extend north from the SPT boundary, terrain reminiscent of Ganymede's grooved terrain, and topographic ridges with multiple orientations. The preliminary

  9. Attitude determination using an adaptive multiple model filtering Scheme

    NASA Technical Reports Server (NTRS)

    Lam, Quang; Ray, Surendra N.

    1995-01-01

    Attitude determination has been considered as a permanent topic of active research and perhaps remaining as a forever-lasting interest for spacecraft system designers. Its role is to provide a reference for controls such as pointing the directional antennas or solar panels, stabilizing the spacecraft or maneuvering the spacecraft to a new orbit. Least Square Estimation (LSE) technique was utilized to provide attitude determination for the Nimbus 6 and G. Despite its poor performance (estimation accuracy consideration), LSE was considered as an effective and practical approach to meet the urgent need and requirement back in the 70's. One reason for this poor performance associated with the LSE scheme is the lack of dynamic filtering or 'compensation'. In other words, the scheme is based totally on the measurements and no attempts were made to model the dynamic equations of motion of the spacecraft. We propose an adaptive filtering approach which employs a bank of Kalman filters to perform robust attitude estimation. The proposed approach, whose architecture is depicted, is essentially based on the latest proof on the interactive multiple model design framework to handle the unknown of the system noise characteristics or statistics. The concept fundamentally employs a bank of Kalman filter or submodel, instead of using fixed values for the system noise statistics for each submodel (per operating condition) as the traditional multiple model approach does, we use an on-line dynamic system noise identifier to 'identify' the system noise level (statistics) and update the filter noise statistics using 'live' information from the sensor model. The advanced noise identifier, whose architecture is also shown, is implemented using an advanced system identifier. To insure the robust performance for the proposed advanced system identifier, it is also further reinforced by a learning system which is implemented (in the outer loop) using neural networks to identify other unknown

  10. JOURNAL SCOPE GUIDELINES: Paper classification scheme

    NASA Astrophysics Data System (ADS)

    2005-06-01

    This scheme is used to clarify the journal's scope and enable authors and readers to more easily locate the appropriate section for their work. For each of the sections listed in the scope statement we suggest some more detailed subject areas which help define that subject area. These lists are by no means exhaustive and are intended only as a guide to the type of papers we envisage appearing in each section. We acknowledge that no classification scheme can be perfect and that there are some papers which might be placed in more than one section. We are happy to provide further advice on paper classification to authors upon request (please email jphysa@iop.org). 1. Statistical physics numerical and computational methods statistical mechanics, phase transitions and critical phenomena quantum condensed matter theory Bose-Einstein condensation strongly correlated electron systems exactly solvable models in statistical mechanics lattice models, random walks and combinatorics field-theoretical models in statistical mechanics disordered systems, spin glasses and neural networks nonequilibrium systems network theory 2. Chaotic and complex systems nonlinear dynamics and classical chaos fractals and multifractals quantum chaos classical and quantum transport cellular automata granular systems and self-organization pattern formation biophysical models 3. Mathematical physics combinatorics algebraic structures and number theory matrix theory classical and quantum groups, symmetry and representation theory Lie algebras, special functions and orthogonal polynomials ordinary and partial differential equations difference and functional equations integrable systems soliton theory functional analysis and operator theory inverse problems geometry, differential geometry and topology numerical approximation and analysis geometric integration computational methods 4. Quantum mechanics and quantum information theory coherent states eigenvalue problems supersymmetric quantum mechanics

  11. Studies of Inviscid Flux Schemes for Acoustics and Turbulence Problems

    NASA Technical Reports Server (NTRS)

    Morris, Chris

    2013-01-01

    Five different central difference schemes, based on a conservative differencing form of the Kennedy and Gruber skew-symmetric scheme, were compared with six different upwind schemes based on primitive variable reconstruction and the Roe flux. These eleven schemes were tested on a one-dimensional acoustic standing wave problem, the Taylor-Green vortex problem and a turbulent channel flow problem. The central schemes were generally very accurate and stable, provided the grid stretching rate was kept below 10%. As near-DNS grid resolutions, the results were comparable to reference DNS calculations. At coarser grid resolutions, the need for an LES SGS model became apparent. There was a noticeable improvement moving from CD-2 to CD-4, and higher-order schemes appear to yield clear benefits on coarser grids. The UB-7 and CU-5 upwind schemes also performed very well at near-DNS grid resolutions. The UB-5 upwind scheme does not do as well, but does appear to be suitable for well-resolved DNS. The UF-2 and UB-3 upwind schemes, which have significant dissipation over a wide spectral range, appear to be poorly suited for DNS or LES.

  12. A chaos secure communication scheme based on multiplication modulation

    NASA Astrophysics Data System (ADS)

    Fallahi, Kia; Leung, Henry

    2010-02-01

    A secure spread spectrum communication scheme using multiplication modulation is proposed. The proposed system multiplies the message by chaotic signal. The scheme does not need to know the initial condition of the chaotic signals and the receiver is based on an extended Kalman filter (EKF). This signal encryption scheme lends itself to cheap implementation and can therefore be used effectively for ensuring security and privacy in commercial consumer electronics products. To illustrate the effectiveness of the proposed scheme, a numerical example based on Genesio-Tesi system and also Chen dynamical system is presented and the results are compared.

  13. Quantum fully homomorphic encryption scheme based on universal quantum circuit

    NASA Astrophysics Data System (ADS)

    Liang, Min

    2015-08-01

    Fully homomorphic encryption enables arbitrary computation on encrypted data without decrypting the data. Here it is studied in the context of quantum information processing. Based on universal quantum circuit, we present a quantum fully homomorphic encryption (QFHE) scheme, which permits arbitrary quantum transformation on any encrypted data. The QFHE scheme is proved to be perfectly secure. In the scheme, the decryption key is different from the encryption key; however, the encryption key cannot be revealed. Moreover, the evaluation algorithm of the scheme is independent of the encryption key, so it is suitable for delegated quantum computing between two parties.

  14. Deducing trapdoor primitives in public key encryption schemes

    NASA Astrophysics Data System (ADS)

    Pandey, Chandra

    2005-03-01

    Semantic security of public key encryption schemes is often interchangeable with the art of building trapdoors. In the frame of reference of Random Oracle methodology, the "Key Privacy" and "Anonymity" has often been discussed. However to a certain degree the security of most public key encryption schemes is required to be analyzed with formal proofs using one-way functions. This paper evaluates the design of El Gamal and RSA based schemes and attempts to parallelize the trapdoor primitives used in the computation of the cipher text, thereby magnifying the decryption error δp in the above schemes.

  15. Quantum messages with signatures forgeable in arbitrated quantum signature schemes

    NASA Astrophysics Data System (ADS)

    Kim, Taewan; Choi, Jeong Woon; Jho, Nam-Su; Lee, Soojoon

    2015-02-01

    Even though a method to perfectly sign quantum messages has not been known, the arbitrated quantum signature scheme has been considered as one of the good candidates. However, its forgery problem has been an obstacle to the scheme becoming a successful method. In this paper, we consider one situation, which is slightly different from the forgery problem, that we use to check whether at least one quantum message with signature can be forged in a given scheme, although all the messages cannot be forged. If there are only a finite number of forgeable quantum messages in the scheme, then the scheme can be secured against the forgery attack by not sending forgeable quantum messages, and so our situation does not directly imply that we check whether the scheme is secure against the attack. However, if users run a given scheme without any consideration of forgeable quantum messages, then a sender might transmit such forgeable messages to a receiver and in such a case an attacker can forge the messages if the attacker knows them. Thus it is important and necessary to look into forgeable quantum messages. We show here that there always exists such a forgeable quantum message-signature pair for every known scheme with quantum encryption and rotation, and numerically show that there are no forgeable quantum message-signature pairs that exist in an arbitrated quantum signature scheme.

  16. A cancellable and fuzzy fingerprint scheme for mobile computing security

    NASA Astrophysics Data System (ADS)

    Yang, Wencheng; Xi, Kai; Li, Cai

    2012-09-01

    Fingerprint recognition provides an effective user authentication solution for mobile computing systems. However, as a fingerprint template protection scheme, fingerprint fuzzy vault is subject to cross-matching attacks, since the same finger might be registered for various applications. In this paper, we propose a fingerprint-based biometric security scheme named the cancellable and fuzzy fingerprint scheme, which combines a cancellable non-linear transformation with the client/server version of fuzzy vault, to address the cross-matching attack in a mobile computing system. Experimental results demonstrate that our scheme can provide reliable and secure protection to the mobile computing system while achieving an acceptable matching performance.

  17. Comparison of two SVD-based color image compression schemes.

    PubMed

    Li, Ying; Wei, Musheng; Zhang, Fengxia; Zhao, Jianli

    2017-01-01

    Color image compression is a commonly used process to represent image data as few bits as possible, which removes redundancy in the data while maintaining an appropriate level of quality for the user. Color image compression algorithms based on quaternion are very common in recent years. In this paper, we propose a color image compression scheme, based on the real SVD, named real compression scheme. First, we form a new real rectangular matrix C according to the red, green and blue components of the original color image and perform the real SVD for C. Then we select several largest singular values and the corresponding vectors in the left and right unitary matrices to compress the color image. We compare the real compression scheme with quaternion compression scheme by performing quaternion SVD using the real structure-preserving algorithm. We compare the two schemes in terms of operation amount, assignment number, operation speed, PSNR and CR. The experimental results show that with the same numbers of selected singular values, the real compression scheme offers higher CR, much less operation time, but a little bit smaller PSNR than the quaternion compression scheme. When these two schemes have the same CR, the real compression scheme shows more prominent advantages both on the operation time and PSNR.

  18. The constant displacement scheme for tracking particles in heterogeneous aquifers

    SciTech Connect

    Wen, X.H.; Gomez-Hernandez, J.J.

    1996-01-01

    Simulation of mass transport by particle tracking or random walk in highly heterogeneous media may be inefficient from a computational point of view if the traditional constant time step scheme is used. A new scheme which adjusts automatically the time step for each particle according to the local pore velocity, so that each particle always travels a constant distance, is shown to be computationally faster for the same degree of accuracy than the constant time step method. Using the constant displacement scheme, transport calculations in a 2-D aquifer model, with nature log-transmissivity variance of 4, can be 8.6 times faster than using the constant time step scheme.

  19. Modified kinetic flux vector splitting schemes for compressible flows

    NASA Astrophysics Data System (ADS)

    Chen, Yibing; Jiang, Song

    2009-06-01

    We investigate the traditional kinetic flux vector splitting (KFVS) and BGK schemes for the compressible Euler equations. First, based on a careful study of the behavior of the discrete physical variables across the contact discontinuity, we analyze quantitatively the mechanism of inducing spurious oscillations of the velocity and pressure in the vicinity of the contact discontinuity for the first-order KFVS and BGK schemes. Then, with the help of this analysis, we propose a first-order modified KFVS (MKFVS) scheme which is oscillation-free in the vicinity of the contact discontinuity, provided certain consistent conditions are satisfied. Moreover, by using piecewise linear reconstruction and van Leer's limiter, the first-order MKFVS scheme is extended to a second-order one, consequently, a nonoscillatory second-order MKFVS scheme is constructed. Finally, by combing the MKFVS schemes with the γ-model, we successfully extend the MKFVS schemes to multi-flows, and propose therefore a first- and second-order MKFVS schemes for multi-fluid computations, which are nonoscillatory across fluid interfaces. A number of numerical examples presented in this paper validate the theoretic analysis and demonstrate the good performance of the MKFVS schemes in simulation of contact discontinuities for both single- and multi-fluids.

  20. Comparison of two SVD-based color image compression schemes

    PubMed Central

    Li, Ying; Wei, Musheng; Zhang, Fengxia; Zhao, Jianli

    2017-01-01

    Color image compression is a commonly used process to represent image data as few bits as possible, which removes redundancy in the data while maintaining an appropriate level of quality for the user. Color image compression algorithms based on quaternion are very common in recent years. In this paper, we propose a color image compression scheme, based on the real SVD, named real compression scheme. First, we form a new real rectangular matrix C according to the red, green and blue components of the original color image and perform the real SVD for C. Then we select several largest singular values and the corresponding vectors in the left and right unitary matrices to compress the color image. We compare the real compression scheme with quaternion compression scheme by performing quaternion SVD using the real structure-preserving algorithm. We compare the two schemes in terms of operation amount, assignment number, operation speed, PSNR and CR. The experimental results show that with the same numbers of selected singular values, the real compression scheme offers higher CR, much less operation time, but a little bit smaller PSNR than the quaternion compression scheme. When these two schemes have the same CR, the real compression scheme shows more prominent advantages both on the operation time and PSNR. PMID:28257451

  1. A Electronic Voting Scheme Achieved by Using Quantum Proxy Signature

    NASA Astrophysics Data System (ADS)

    Cao, Hai-Jing; Ding, Li-Yuan; Yu, Yao-Feng; Li, Peng-Fei

    2016-09-01

    In this paper, we propose a new electronic voting scheme using Bell entangled states as quantum channels. This scheme is based on quantum proxy signature. The voter Alice, vote management center Bob, teller Charlie and scrutineer Diana only perform single particle measurement to realize the electronic voting process. So the scheme reduces the technical difficulty and increases operation efficiency. It can be easily realized. We use quantum key distribution and one-time pad to guarantee its unconditional security. The scheme uses the physical characteristics of quantum mechanics to guarantee its anonymity, verifiability, unforgetability and undeniability.

  2. Activities.

    ERIC Educational Resources Information Center

    Kincaid, Charlene; And Others

    1993-01-01

    Presents an activity in which students collect and organize data from a real-world simulation of the scientific concept of half life. Students collect data using a marble sifter, analyze the data using a graphing calculator, and determine an appropriate mathematical model. Includes reproducible worksheets. (MDH)

  3. On a fourth order accurate implicit finite difference scheme for hyperbolic conservation laws. II - Five-point schemes

    NASA Technical Reports Server (NTRS)

    Harten, A.; Tal-Ezer, H.

    1981-01-01

    This paper presents a family of two-level five-point implicit schemes for the solution of one-dimensional systems of hyperbolic conservation laws, which generalized the Crank-Nicholson scheme to fourth order accuracy (4-4) in both time and space. These 4-4 schemes are nondissipative and unconditionally stable. Special attention is given to the system of linear equations associated with these 4-4 implicit schemes. The regularity of this system is analyzed and efficiency of solution-algorithms is examined. A two-datum representation of these 4-4 implicit schemes brings about a compactification of the stencil to three mesh points at each time-level. This compact two-datum representation is particularly useful in deriving boundary treatments. Numerical results are presented to illustrate some properties of the proposed scheme.

  4. A Self-Adaptive Behavior-Aware Recruitment Scheme for Participatory Sensing.

    PubMed

    Zeng, Yuanyuan; Li, Deshi

    2015-09-16

    Participatory sensing services utilizing the abundant social participants with sensor-enabled handheld smart device resources are gaining high interest nowadays. One of the challenges faced is the recruitment of participants by fully utilizing their daily activity behavior with self-adaptiveness toward the realistic application scenarios. In the paper, we propose a self-adaptive behavior-aware recruitment scheme for participatory sensing. People are assumed to join the sensing tasks along with their daily activity without pre-defined ground truth or any instructions. The scheme is proposed to model the tempo-spatial behavior and data quality rating to select participants for participatory sensing campaign. Based on this, the recruitment is formulated as a linear programming problem by considering tempo-spatial coverage, data quality, and budget. The scheme enables one to check and adjust the recruitment strategy adaptively according to application scenarios. The evaluations show that our scheme provides efficient sensing performance as stability, low-cost, tempo-spatial correlation and self-adaptiveness.

  5. Nonlinear force-free coronal magnetic field extrapolation scheme based on the direct boundary integral formulation

    NASA Astrophysics Data System (ADS)

    He, Han; Wang, Huaning

    2008-05-01

    The boundary integral equation (BIE) method was first proposed by Yan and Sakurai (2000) and used to extrapolate the nonlinear force-free magnetic field in the solar atmosphere. Recently, Yan and Li (2006) improved the BIE method and proposed the direct boundary integral equation (DBIE) formulation, which represents the nonlinear force-free magnetic field by direct integration of the magnetic field on the bottom boundary surface. On the basis of this new method, we devised a practical calculation scheme for the nonlinear force-free field extrapolation above solar active regions. The code of the scheme was tested by the analytical solutions of Low and Lou (1990) and was applied to the observed vector magnetogram of solar active region NOAA 9077. The results of the calculations show that the improvement of the new computational scheme to the scheme of Yan and Li (2006) is significant, and the force-free and divergence-free constraints are well satisfied in the extrapolated fields. The calculated field lines for NOAA 9077 present the X-shaped structure and can be helpful for understanding the magnetic configuration of the filament channel as well as the magnetic reconnection process during the Bastille Day flare on 14 July 2000.

  6. Multi-rate time stepping schemes for hydro-geomechanical model for subsurface methane hydrate reservoirs

    NASA Astrophysics Data System (ADS)

    Gupta, Shubhangi; Wohlmuth, Barbara; Helmig, Rainer

    2016-05-01

    We present an extrapolation-based semi-implicit multi-rate time stepping (MRT) scheme and a compound-fast MRT scheme for a naturally partitioned, multi-time-scale hydro-geomechanical hydrate reservoir model. We evaluate the performance of the two MRT methods compared to an iteratively coupled solution scheme and discuss their advantages and disadvantages. The performance of the two MRT methods is evaluated in terms of speed-up and accuracy by comparison to an iteratively coupled solution scheme. We observe that the extrapolation-based semi-implicit method gives a higher speed-up but is strongly dependent on the relative time scales of the latent (slow) and active (fast) components. On the other hand, the compound-fast method is more robust and less sensitive to the relative time scales, but gives lower speed up as compared to the semi-implicit method, especially when the relative time scales of the active and latent components are comparable.

  7. Scheme for accelerating quantum tunneling dynamics

    NASA Astrophysics Data System (ADS)

    Khujakulov, Anvar; Nakamura, Katsuhiro

    2016-02-01

    We propose a scheme of the exact fast forwarding of standard quantum dynamics for a charged particle. The present idea allows the acceleration of both the amplitude and the phase of the wave function throughout the fast-forward time range and is distinct from that of Masuda and Nakamura [Proc. R. Soc. A 466, 1135 (2010), 10.1098/rspa.2009.0446], which enabled acceleration of only the amplitude of the wave function on the way. We apply the proposed method to the quantum tunneling phenomena and obtain the electromagnetic field to ensure the rapid penetration of wave functions through a tunneling barrier. Typical examples described here are (1) an exponential wave packet passing through the δ -function barrier and (2) the opened Moshinsky shutter with a δ -function barrier just behind the shutter. We elucidate the tunneling current in the vicinity of the barrier and find a remarkable enhancement of the tunneling rate (tunneling power) due to the fast forwarding. In the case of a very high barrier, in particular, we present the asymptotic analysis and exhibit a suitable driving force to recover a recognizable tunneling current. The analysis is also carried out on the exact acceleration of macroscopic quantum tunneling with use of the nonlinear Schrödinger equation, which accommodates a tunneling barrier.

  8. Date attachable offline electronic cash scheme.

    PubMed

    Fan, Chun-I; Sun, Wei-Zhe; Hau, Hoi-Tung

    2014-01-01

    Electronic cash (e-cash) is definitely one of the most popular research topics in the e-commerce field. It is very important that e-cash be able to hold the anonymity and accuracy in order to preserve the privacy and rights of customers. There are two types of e-cash in general, which are online e-cash and offline e-cash. Both systems have their own pros and cons and they can be used to construct various applications. In this paper, we pioneer to propose a provably secure and efficient offline e-cash scheme with date attachability based on the blind signature technique, where expiration date and deposit date can be embedded in an e-cash simultaneously. With the help of expiration date, the bank can manage the huge database much more easily against unlimited growth, and the deposit date cannot be forged so that users are able to calculate the amount of interests they can receive in the future correctly. Furthermore, we offer security analysis and formal proofs for all essential properties of offline e-cash, which are anonymity control, unforgeability, conditional-traceability, and no-swindling.

  9. Multiview image compression based on LDV scheme

    NASA Astrophysics Data System (ADS)

    Battin, Benjamin; Niquin, Cédric; Vautrot, Philippe; Debons, Didier; Lucas, Laurent

    2011-03-01

    In recent years, we have seen several different approaches dealing with multiview compression. First, we can find the H264/MVC extension which generates quite heavy bitstreams when used on n-views autostereoscopic medias and does not allow inter-view reconstruction. Another solution relies on the MVD (MultiView+Depth) scheme which keeps p views (n > p > 1) and their associated depth-maps. This method is not suitable for multiview compression since it does not exploit the redundancy between the p views, moreover occlusion areas cannot be accurately filled. In this paper, we present our method based on the LDV (Layered Depth Video) approach which keeps one reference view with its associated depth-map and the n-1 residual ones required to fill occluded areas. We first perform a global per-pixel matching step (providing a good consistency between each view) in order to generate one unified-color RGB texture (where a unique color is devoted to all pixels corresponding to the same 3D-point, thus avoiding illumination artifacts) and a signed integer disparity texture. Next, we extract the non-redundant information and store it into two textures (a unified-color one and a disparity one) containing the reference and the n-1 residual views. The RGB texture is compressed with a conventional DCT or DWT-based algorithm and the disparity texture with a lossless dictionary algorithm. Then, we will discuss about the signal deformations generated by our approach.

  10. Environmental endocrine disruptors: A proposed classification scheme

    SciTech Connect

    Fur, P.L. de; Roberts, J.

    1995-12-31

    A number of chemicals known to act on animal systems through the endocrine system have been termed environmental endocrine disruptors. This group includes some of the PCBs and TCDDs, as well as lead, mercury and a large number of pesticides. The common feature is that the chemicals interact with endogenous endocrine systems at the cellular and/or molecular level to alter normal processes that are controlled or regulated by hormones. Although the existence of artificial or environmental estrogens (e.g. chlordecone and DES) has been known for some time, recent data indicate that this phenomenon is widespread. Indeed, anti-androgens have been held responsible for reproductive dysfunction in alligator populations in Florida. But the significance of endocrine disruption was recognized by pesticide manufacturers when insect growth regulators were developed to interfere with hormonal control of growth. Controlling, regulating or managing these chemicals depends in no small part on the ability to identify, screen or otherwise know that a chemical is an endocrine disrupter. Two possible classifications schemes are: using the effects caused in an animal, or animals as an exposure indicator; and using a known screen for the point of contact with the animal. The former would require extensive knowledge of cause and effect relationships in dozens of animal groups; the latter would require a screening tool comparable to an estrogen binding assay. The authors present a possible classification based on chemicals known to disrupt estrogenic, androgenic and ecdysone regulated hormonal systems.

  11. Medical aid schemes respond to AIDS.

    PubMed

    Taylor, G

    1999-01-01

    The insurance and medical aid industries reacted strongly in the 1980s to alarmist predictions of the likely impact of HIV upon employee benefits. Actuaries and accountants moved quickly to contain the risk, and most medical aid trustees quickly implemented a total exclusion of HIV treatment from their benefits. For more than 1 decade, it was argued that HIV/AIDS is a self-inflicted illness, often categorized with other STDs. In response, healthcare providers simply bypassed insurance restrictions and compensation limits by masking patient diagnoses to reflect pneumonia or other ambiguous, yet fully reimbursable, illnesses. Now, common sense has finally prevailed as a few managed healthcare programs are stepping forward to break the impasse. The largest such program is Aid for AIDS, run by Pharmaceutical Benefit Management Ltd. for schemes within the Medscheme Group. The Group built an entirely new, secure unit off-site from their normal branches to guarantee the confidentiality of patients' records and diagnoses, while treatment guidelines have been issued to every practicing physician in the country.

  12. A community training scheme in cardiopulmonary resuscitation.

    PubMed Central

    Vincent, R; Martin, B; Williams, G; Quinn, E; Robertson, G; Chamberlain, D A

    1984-01-01

    Community instruction in basic life support and resuscitation techniques has been offered in Brighton Health District since 1978. Classes are held frequently for the general public and businesses, schools, and other organisations. First aid care for unconscious patients, the treatment of respiratory obstruction or failure, and the recognition and management of cardiac arrest is taught in a single two hour session. Over 20 000 people have been taught, up to 40 at a time in multiple groups of six to eight, by lay instructors usually supervised by ambulancemen trained to "paramedic" standards. Fifty four incidents have been reported to us in which techniques learnt in the classes have been implemented. Five patients recovered after first aid support but subsequently did not seek medical treatment. Of the 34 patients reviewed in hospital, at least 20 survived to be discharged. We believe that intervention may have been life saving in 16 instances. The benefit of cardiopulmonary resuscitation for victims who may have been asystolic is, however, difficult to quantify because the outcome without intervention cannot be predicted accurately. Community training in basic life support should be considered in association with ambulances equipped for resuscitation and hospital intensive care and cardiac care units as an integrated service for the victims of sudden circulatory or respiratory emergencies. The results achieved so far in Brighton and in other more advanced schemes, particularly in the United States of America, may encourage other health authorities to adopt similar programmes. PMID:6421403

  13. Nonlinear inversion schemes for fluorescence optical tomography.

    PubMed

    Freiberger, Manuel; Egger, Herbert; Scharfetter, Hermann

    2010-11-01

    Fluorescence optical tomography is a non-invasive imaging modality that employs the absorption and re-emission of light by fluorescent dyes. The aim is to reconstruct the fluorophore distribution in a body from measurements of light intensities at the boundary. Due to the diffusive nature of light propagation in tissue, fluorescence tomography is a nonlinear and severely ill-posed problem, and some sort of regularization is required for a stable solution. In this paper we investigate reconstruction methods based on Tikhonov regularization with nonlinear penalty terms, namely total-variation regularization and a levelset-type method using a nonlinear parameterization of the unknown function. Moreover, we use the full threedimensional nonlinear forward model, which arises from the governing system of partial differential equations. We discuss the numerical realization of the regularization schemes by Newtontype iterations, present some details of the discretization by finite element methods, and outline the efficient implementation of sensitivity systems via adjoint methods. As we will demonstrate in numerical tests, the proposed nonlinear methods provide better reconstructions than standard methods based on linearized forward models and linear penalty terms. We will additionally illustrate, that the careful discretization of the methods derived on the continuous level allows to obtain reliable, mesh independent reconstruction algorithms.

  14. Date Attachable Offline Electronic Cash Scheme

    PubMed Central

    Sun, Wei-Zhe; Hau, Hoi-Tung

    2014-01-01

    Electronic cash (e-cash) is definitely one of the most popular research topics in the e-commerce field. It is very important that e-cash be able to hold the anonymity and accuracy in order to preserve the privacy and rights of customers. There are two types of e-cash in general, which are online e-cash and offline e-cash. Both systems have their own pros and cons and they can be used to construct various applications. In this paper, we pioneer to propose a provably secure and efficient offline e-cash scheme with date attachability based on the blind signature technique, where expiration date and deposit date can be embedded in an e-cash simultaneously. With the help of expiration date, the bank can manage the huge database much more easily against unlimited growth, and the deposit date cannot be forged so that users are able to calculate the amount of interests they can receive in the future correctly. Furthermore, we offer security analysis and formal proofs for all essential properties of offline e-cash, which are anonymity control, unforgeability, conditional-traceability, and no-swindling. PMID:24982931

  15. Suboptimal fractal coding scheme using iterative transformation

    NASA Astrophysics Data System (ADS)

    Kang, Hyun-Soo; Chung, Jae-won

    2001-05-01

    This paper presents a new fractal coding scheme to find a suboptimal transformation by performing an iterative encoding process. The optimal transformation can be defined as the transformation generating the closest attractor to an original image. Unfortunately, it is impossible in practice to find the optimal transformation, due to the heavy computational burden. In this paper, however, by means of some new theorems related with contractive transformations and attractors. It is shown that for some specific cases the optimal or suboptimal transformations can be obtained. The proposed method obtains a suboptimal transformation by performing iterative processes as is done in decoding. Thus, it requires more computation than the conventional method, but it improves the image quality. For a simple case where the optimal transformation can actually be found, the proposed method is experimentally evaluated against both the optimal method and the conventional method. For a general case where the optimal transformation in unavailable due to heavy computational complexity, the proposed method is also evaluated in comparison with the conventional method.

  16. Efficient lossless compression scheme for multispectral images

    NASA Astrophysics Data System (ADS)

    Benazza-Benyahia, Amel; Hamdi, Mohamed; Pesquet, Jean-Christophe

    2001-12-01

    Huge amounts of data are generated thanks to the continuous improvement of remote sensing systems. Archiving this tremendous volume of data is a real challenge which requires lossless compression techniques. Furthermore, progressive coding constitutes a desirable feature for telebrowsing. To this purpose, a compact and pyramidal representation of the input image has to be generated. Separable multiresolution decompositions have already been proposed for multicomponent images allowing each band to be decomposed separately. It seems however more appropriate to exploit also the spectral correlations. For hyperspectral images, the solution is to apply a 3D decomposition according to the spatial and to the spectral dimensions. This approach is not appropriate for multispectral images because of the reduced number of spectral bands. In recent works, we have proposed a nonlinear subband decomposition scheme with perfect reconstruction which exploits efficiently both the spatial and the spectral redundancies contained in multispectral images. In this paper, the problem of coding the coefficients of the resulting subband decomposition is addressed. More precisely, we propose an extension to the vector case of Shapiro's embedded zerotrees of wavelet coefficients (V-EZW) with achieves further saving in the bit stream. Simulations carried out on SPOT images indicate the outperformance of the global compression package we performed.

  17. PPLN Device Characterization and Novel Entanglement Schemes

    NASA Astrophysics Data System (ADS)

    Krupa, Sean; Stinaff, Eric; Nippa, David; Oesterling, Lee

    2013-03-01

    Bright sources of entangled photons are of great interest in the quantum information community, and the non-linear optical process of Spontaneous Parametric Downconversion (SPDC) is a well-known means to create entangled photons. Additionally, periodic polling has emerged as a viable choice for quasi-phase matching the downconverted photons rendering them useful for experimentation. Periodically Poled Lithium Niobate (PPLN) is among the best choices for these materials as it optically robust, temperature tunable, and commercially available. The addition of waveguide structures in PPLN devices not only increase its viability as a source of entangled photons but can also become an integral part of the entanglement schemes as well. Thorough characterization of PPLN devices is essential for the optimization of SPDC and their use to create entangled states. We will report characterization results for wave-guided PPLN devices including: waveguide geometry, fiber coupling efficiency, polling period details, and downconversion efficiency. Of particular interest is our device's ability to be used for novel entanglement states involving one or more waveguides.

  18. The new cooperative medical scheme in China.

    PubMed

    You, Xuedan; Kobayashi, Yasuki

    2009-06-01

    The New Cooperative Medical Scheme (NCMS) is a heavily subsidized voluntary health insurance program established in 2003 to reduce the risk of catastrophic health spending for rural residents in China. In this review, we present the current collection of knowledge available regarding the performance of NCMS on the aspects of revenue collection, risk pooling, reimbursement rules and provider payment. The available evidence suggests that NCMS has substantially improved health care access and utilization among the participants; however, it appears to have no statistically significant effect on average household out-of-pocket health spending and catastrophic expenditure risk. As NCMS is rolled out to other counties, it must be careful to generalize the findings reported in the published papers and reports, because the early pilot counties were not randomly selected and there are a lot of local adaptations. In addition, we expect that NCMS could be an important opportunity to establish some trust-based institutions in the best interest of the participants to monitor provider quality and control cost inflation. Rigorous evaluations, based on richer and latest micro-level data, could considerably strengthen the evidence base for the performance and impact of NCMS.

  19. On schemes of combinatorial transcription logic.

    PubMed

    Buchler, Nicolas E; Gerland, Ulrich; Hwa, Terence

    2003-04-29

    Cells receive a wide variety of cellular and environmental signals, which are often processed combinatorially to generate specific genetic responses. Here we explore theoretically the potentials and limitations of combinatorial signal integration at the level of cis-regulatory transcription control. Our analysis suggests that many complex transcription-control functions of the type encountered in higher eukaryotes are already implementable within the much simpler bacterial transcription system. Using a quantitative model of bacterial transcription and invoking only specific protein-DNA interaction and weak glue-like interaction between regulatory proteins, we show explicit schemes to implement regulatory logic functions of increasing complexity by appropriately selecting the strengths and arranging the relative positions of the relevant protein-binding DNA sequences in the cis-regulatory region. The architectures that emerge are naturally modular and evolvable. Our results suggest that the transcription regulatory apparatus is a "programmable" computing machine, belonging formally to the class of Boltzmann machines. Crucial to our results is the ability to regulate gene expression at a distance. In bacteria, this can be achieved for isolated genes via DNA looping controlled by the dimerization of DNA-bound proteins. However, if adopted extensively in the genome, long-distance interaction can cause unintentional intergenic cross talk, a detrimental side effect difficult to overcome by the known bacterial transcription-regulation systems. This may be a key factor limiting the genome-wide adoption of complex transcription control in bacteria. Implications of our findings for combinatorial transcription control in eukaryotes are discussed.

  20. Splitting based finite volume schemes for ideal MHD equations

    NASA Astrophysics Data System (ADS)

    Fuchs, F. G.; Mishra, S.; Risebro, N. H.

    2009-02-01

    We design finite volume schemes for the equations of ideal magnetohydrodynamics (MHD) and based on splitting these equations into a fluid part and a magnetic induction part. The fluid part leads to an extended Euler system with magnetic forces as source terms. This set of equations are approximated by suitable two- and three-wave HLL solvers. The magnetic part is modeled by the magnetic induction equations which are approximated using stable upwind schemes devised in a recent paper [F. Fuchs, K.H. Karlsen, S. Mishra, N.H. Risebro, Stable upwind schemes for the Magnetic Induction equation. Math. Model. Num. Anal., Available on conservation laws preprint server, submitted for publication, URL: ]. These two sets of schemes can be combined either component by component, or by using an operator splitting procedure to obtain a finite volume scheme for the MHD equations. The resulting schemes are simple to design and implement. These schemes are compared with existing HLL type and Roe type schemes for MHD equations in a series of numerical experiments. These tests reveal that the proposed schemes are robust and have a greater numerical resolution than HLL type solvers, particularly in several space dimensions. In fact, the numerical resolution is comparable to that of the Roe scheme on most test problems with the computational cost being at the level of a HLL type solver. Furthermore, the schemes are remarkably stable even at very fine mesh resolutions and handle the divergence constraint efficiently with low divergence errors.

  1. An optimized spectral difference scheme for CAA problems

    NASA Astrophysics Data System (ADS)

    Gao, Junhui; Yang, Zhigang; Li, Xiaodong

    2012-05-01

    In the implementation of spectral difference (SD) method, the conserved variables at the flux points are calculated from the solution points using extrapolation or interpolation schemes. The errors incurred in using extrapolation and interpolation would result in instability. On the other hand, the difference between the left and right conserved variables at the edge interface will introduce dissipation to the SD method when applying a Riemann solver to compute the flux at the element interface. In this paper, an optimization of the extrapolation and interpolation schemes for the fourth order SD method on quadrilateral element is carried out in the wavenumber space through minimizing their dispersion error over a selected band of wavenumbers. The optimized coefficients of the extrapolation and interpolation are presented. And the dispersion error of the original and optimized schemes is plotted and compared. An improvement of the dispersion error over the resolvable wavenumber range of SD method is obtained. The stability of the optimized fourth order SD scheme is analyzed. It is found that the stability of the 4th order scheme with Chebyshev-Gauss-Lobatto flux points, which is originally weakly unstable, has been improved through the optimization. The weak instability is eliminated completely if an additional second order filter is applied on selected flux points. One and two dimensional linear wave propagation analyses are carried out for the optimized scheme. It is found that in the resolvable wavenumber range the new SD scheme is less dispersive and less dissipative than the original scheme, and the new scheme is less anisotropic for 2D wave propagation. The optimized SD solver is validated with four computational aeroacoustics (CAA) workshop benchmark problems. The numerical results with optimized schemes agree much better with the analytical data than those with the original schemes.

  2. A Parcellation Scheme for Human Left Lateral Parietal Cortex

    PubMed Central

    Nelson, Steven M.; Cohen, Alexander L.; Power, Jonathan D.; Wig, Gagan S.; Miezin, Francis M.; Wheeler, Mark E.; Velanova, Katerina; Donaldson, David I.; Phillips, Jeffrey S.; Schlaggar, Bradley L.; Petersen, Steven E.

    2010-01-01

    SUMMARY The parietal lobe has long been viewed as a collection of architectonic and functional subdivisions. Though much parietal research has focused on mechanisms of visuospatial attention and control-related processes, more recent functional neuroimaging studies of memory retrieval have reported greater activity in left lateral parietal cortex (LLPC) when items are correctly identified as previously studied (“old”) vs. unstudied (“new”). These studies have suggested functional divisions within LLPC that may provide distinct contributions towards recognition memory judgments. Here, we define regions within LLPC by developing a novel parcellation scheme that integrates data from resting state functional connectivity MRI (rsfcMRI) and functional MRI (fMRI). This combined approach results in a six-fold parcellation of LLPC based on the presence (or absence) of memory retrieval-related activity, dissociations in the profile of task-evoked timecourses, and membership in large-scale brain networks. This parcellation should serve as a roadmap for future investigations aimed at understanding LLPC function. PMID:20624599

  3. Performance improvement of robots using a learning control scheme

    NASA Technical Reports Server (NTRS)

    Krishna, Ramuhalli; Chiang, Pen-Tai; Yang, Jackson C. S.

    1987-01-01

    Many applications of robots require that the same task be repeated a number of times. In such applications, the errors associated with one cycle are also repeated every cycle of the operation. An off-line learning control scheme is used here to modify the command function which would result in smaller errors in the next operation. The learning scheme is based on a knowledge of the errors and error rates associated with each cycle. Necessary conditions for the iterative scheme to converge to zero errors are derived analytically considering a second order servosystem model. Computer simulations show that the errors are reduced at a faster rate if the error rate is included in the iteration scheme. The results also indicate that the scheme may increase the magnitude of errors if the rate information is not included in the iteration scheme. Modification of the command input using a phase and gain adjustment is also proposed to reduce the errors with one attempt. The scheme is then applied to a computer model of a robot system similar to PUMA 560. Improved performance of the robot is shown by considering various cases of trajectory tracing. The scheme can be successfully used to improve the performance of actual robots within the limitations of the repeatability and noise characteristics of the robot.

  4. Distinguishing Schemes and Tasks in Children's Development of Multiplicative Reasoning

    ERIC Educational Resources Information Center

    Tzur, Ron; Johnson, Heather L.; McClintock, Evan; Kenney, Rachael H.; Xin, Yan P.; Si, Luo; Woordward, Jerry; Hord, Casey; Jin, Xianyan

    2013-01-01

    We present a synthesis of findings from constructivist teaching experiments regarding six schemes children construct for reasoning multiplicatively and tasks to promote them. We provide a task-generating platform game, depictions of each scheme, and supporting tasks. Tasks must be distinguished from children's thinking, and learning situations…

  5. Ranking Schemes in Hybrid Boolean Systems: A New Approach.

    ERIC Educational Resources Information Center

    Savoy, Jacques

    1997-01-01

    Suggests a new ranking scheme especially adapted for hypertext environments in order to produce more effective retrieval results and still use Boolean search strategies. Topics include Boolean ranking schemes; single-term indexing and term weighting; fuzzy set theory extension; and citation indexing. (64 references) (Author/LRW)

  6. Stable explicit schemes for equations of Schroedinger type

    NASA Technical Reports Server (NTRS)

    Mickens, Ronald E.

    1989-01-01

    A method for constructing explicit finite-difference schemes which can be used to solve Schroedinger-type partial-differential equations is presented. A forward Euler scheme that is conditionally stable is given by the procedure. The results presented are based on the analysis of the simplest Schroedinger type equation.

  7. Dropping out of Ethiopia's community-based health insurance scheme.

    PubMed

    Mebratie, Anagaw D; Sparrow, Robert; Yilma, Zelalem; Alemu, Getnet; Bedi, Arjun S

    2015-12-01

    Low contract renewal rates have been identified as one of the challenges facing the development of community-based health insurance (CBHI) schemes. This article uses longitudinal household survey data gathered in 2012 and 2013 to examine dropout in the case of Ethiopia's pilot CBHI scheme. We treat dropout as a function of scheme affordability, health status, scheme understanding and quality of care. The scheme saw enrolment increase from 41% 1 year after inception to 48% a year later. An impressive 82% of those who enrolled in the first year renewed their subscriptions, while 25% who had not enrolled joined the scheme. The analysis shows that socioeconomic status, a greater understanding of health insurance and experience with and knowledge of the CBHI scheme are associated with lower dropout rates. While there are concerns about the quality of care and the treatment meted out to the insured by providers, the overall picture is that returns from the scheme are overwhelmingly positive. For the bulk of households, premiums do not seem to be onerous, basic understanding of health insurance is high and almost all those who are currently enrolled signalled their desire to renew contracts.

  8. 7 CFR 12.10 - Scheme or device.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 1 2014-01-01 2014-01-01 false Scheme or device. 12.10 Section 12.10 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION General Provisions § 12.10 Scheme or device. All or any part of the benefits listed in § 12.4 otherwise due a person...

  9. 7 CFR 12.10 - Scheme or device.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 1 2013-01-01 2013-01-01 false Scheme or device. 12.10 Section 12.10 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION General Provisions § 12.10 Scheme or device. All or any part of the benefits listed in § 12.4 otherwise due a person...

  10. 7 CFR 1467.19 - Scheme and device.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Scheme and device. 1467.19 Section 1467.19 Agriculture Regulations of the Department of Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS WETLANDS RESERVE PROGRAM § 1467.19 Scheme...

  11. 7 CFR 12.10 - Scheme or device.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 1 2011-01-01 2011-01-01 false Scheme or device. 12.10 Section 12.10 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION General Provisions § 12.10 Scheme or device. All or any part of the benefits listed in § 12.4 otherwise due a person...

  12. 7 CFR 12.10 - Scheme or device.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Scheme or device. 12.10 Section 12.10 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION General Provisions § 12.10 Scheme or device. All or any part of the benefits listed in § 12.4 otherwise due a person...

  13. 7 CFR 12.10 - Scheme or device.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 1 2012-01-01 2012-01-01 false Scheme or device. 12.10 Section 12.10 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION General Provisions § 12.10 Scheme or device. All or any part of the benefits listed in § 12.4 otherwise due a person...

  14. Stable Difference Schemes for the Neutron Transport Equation

    NASA Astrophysics Data System (ADS)

    Ashyralyev, Allaberen; Taskin, Abdulgafur

    2011-09-01

    The initial boundary value problem for the neutron transport equation is considered. The first and second orders of accuracy difference schemes for the approximate solution of this problem are presented. In applications, the stability estimates for solutions of difference schemes for the approximate solution of the neutron transport equation are obtained. Numerical techniques are developed and algorithms are tested on an example in MATLAB.

  15. Convergence Acceleration for Multistage Time-Stepping Schemes

    NASA Technical Reports Server (NTRS)

    Swanson, R. C.; Turkel, Eli L.; Rossow, C-C; Vasta, V. N.

    2006-01-01

    The convergence of a Runge-Kutta (RK) scheme with multigrid is accelerated by preconditioning with a fully implicit operator. With the extended stability of the Runge-Kutta scheme, CFL numbers as high as 1000 could be used. The implicit preconditioner addresses the stiffness in the discrete equations associated with stretched meshes. Numerical dissipation operators (based on the Roe scheme, a matrix formulation, and the CUSP scheme) as well as the number of RK stages are considered in evaluating the RK/implicit scheme. Both the numerical and computational efficiency of the scheme with the different dissipation operators are discussed. The RK/implicit scheme is used to solve the two-dimensional (2-D) and three-dimensional (3-D) compressible, Reynolds-averaged Navier-Stokes equations. In two dimensions, turbulent flows over an airfoil at subsonic and transonic conditions are computed. The effects of mesh cell aspect ratio on convergence are investigated for Reynolds numbers between 5.7 x 10(exp 6) and 100.0 x 10(exp 6). Results are also obtained for a transonic wing flow. For both 2-D and 3-D problems, the computational time of a well-tuned standard RK scheme is reduced at least a factor of four.

  16. On the novel chaotic secure communication scheme design

    NASA Astrophysics Data System (ADS)

    Wang, B.; Zhong, S. M.; Dong, X. C.

    2016-10-01

    In this paper, the problem on the chaotic secure communication is discussed. First a new dual channel transmission mechanism is presented and used in secure communication scheme design, then the channel-switching techniques are adopted to further improve the security of information transmission. Finally some typical numerical simulations are carried out to demonstrate the effectiveness of the proposed secure communication scheme.

  17. Quantum secret sharing schemes and reversibility of quantum operations

    SciTech Connect

    Ogawa, Tomohiro; Sasaki, Akira; Iwamoto, Mitsugu; Yamamoto, Hirosuke

    2005-09-15

    Quantum secret sharing schemes encrypting a quantum state into a multipartite entangled state are treated. The lower bound on the dimension of each share given by Gottesman [Phys. Rev. A 61, 042311 (2000)] is revisited based on a relation between the reversibility of quantum operations and the Holevo information. We also propose a threshold ramp quantum secret sharing scheme and evaluate its coding efficiency.

  18. Resolution-optimised nonlinear scheme for secondary derivatives

    NASA Astrophysics Data System (ADS)

    Li, Li; Yu, Changping; Chen, Zhe; Li, Xinliang

    2016-02-01

    A 5-point-stencil optimised nonlinear scheme with spectral-like resolution within the whole wave number range for secondary derivatives is devised. The proposed scheme can compensate for the dissipation deficiency of traditional linear schemes and suppress the spurious energy accumulation that occurs at high wave numbers, both of which are frequently encountered in large eddy simulation. The new scheme is composed of a linear fourth-order central scheme term and an artificial viscosity term. These two terms are connected by a nonlinear weight. The proposed nonlinear weight is designed based on Fourier analysis, rather than Taylor analysis, to guarantee a spectral-like resolution. Moreover, the accuracy is not affected by the optimisation, and the new scheme reaches fourth-order accuracy. The new scheme is tested numerically using the one-dimensional diffusion problem, one-dimensional steady viscous Burger's shock, two-dimensional vortex decaying, three-dimensional isotropic decaying turbulence and fully developed turbulent channel flow. All the tests confirm that the new scheme has spectral-like resolution and can improve the accuracy of the energy spectrum, dissipation rate and high-order statistics of turbulent flows.

  19. New User Support in the University Network with DACS Scheme

    ERIC Educational Resources Information Center

    Odagiri, Kazuya; Yaegashi, Rihito; Tadauchi, Masaharu; Ishii, Naohiro

    2007-01-01

    Purpose: The purpose of this paper is to propose and examine the new user support in university network. Design/methodology/approach: The new user support is realized by use of DACS (Destination Addressing Control System) Scheme which manages a whole network system through communication control on a client computer. This DACS Scheme has been…

  20. Second-order accurate nonoscillatory schemes for scalar conservation laws

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1989-01-01

    Explicit finite difference schemes for the computation of weak solutions of nonlinear scalar conservation laws is presented and analyzed. These schemes are uniformly second-order accurate and nonoscillatory in the sense that the number of extrema of the discrete solution is not increasing in time.

  1. LDPC-PPM Coding Scheme for Optical Communication

    NASA Technical Reports Server (NTRS)

    Barsoum, Maged; Moision, Bruce; Divsalar, Dariush; Fitz, Michael

    2009-01-01

    In a proposed coding-and-modulation/demodulation-and-decoding scheme for a free-space optical communication system, an error-correcting code of the low-density parity-check (LDPC) type would be concatenated with a modulation code that consists of a mapping of bits to pulse-position-modulation (PPM) symbols. Hence, the scheme is denoted LDPC-PPM. This scheme could be considered a competitor of a related prior scheme in which an outer convolutional error-correcting code is concatenated with an interleaving operation, a bit-accumulation operation, and a PPM inner code. Both the prior and present schemes can be characterized as serially concatenated pulse-position modulation (SCPPM) coding schemes. Figure 1 represents a free-space optical communication system based on either the present LDPC-PPM scheme or the prior SCPPM scheme. At the transmitting terminal, the original data (u) are processed by an encoder into blocks of bits (a), and the encoded data are mapped to PPM of an optical signal (c). For the purpose of design and analysis, the optical channel in which the PPM signal propagates is modeled as a Poisson point process. At the receiving terminal, the arriving optical signal (y) is demodulated to obtain an estimate (a^) of the coded data, which is then processed by a decoder to obtain an estimate (u^) of the original data.

  2. 7 CFR 1415.20 - Scheme or device.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Scheme or device. 1415.20 Section 1415.20 Agriculture Regulations of the Department of Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS GRASSLANDS RESERVE PROGRAM § 1415.20 Scheme or device....

  3. 7 CFR 1415.20 - Scheme or device.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Scheme or device. 1415.20 Section 1415.20 Agriculture Regulations of the Department of Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS GRASSLANDS RESERVE PROGRAM § 1415.20 Scheme or device....

  4. 7 CFR 1415.20 - Scheme or device.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Scheme or device. 1415.20 Section 1415.20 Agriculture Regulations of the Department of Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS GRASSLANDS RESERVE PROGRAM § 1415.20 Scheme or device....

  5. 7 CFR 1415.20 - Scheme or device.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Scheme or device. 1415.20 Section 1415.20 Agriculture Regulations of the Department of Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS GRASSLANDS RESERVE PROGRAM § 1415.20 Scheme or device....

  6. 7 CFR 1415.20 - Scheme or device.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Scheme or device. 1415.20 Section 1415.20 Agriculture Regulations of the Department of Agriculture (Continued) COMMODITY CREDIT CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS GRASSLANDS RESERVE PROGRAM § 1415.20 Scheme or device....

  7. A FRACTAL-BASED STOCHASTIC INTERPOLATION SCHEME IN SUBSURFACE HYDROLOGY

    EPA Science Inventory

    The need for a realistic and rational method for interpolating sparse data sets is widespread. Real porosity and hydraulic conductivity data do not vary smoothly over space, so an interpolation scheme that preserves irregularity is desirable. Such a scheme based on the properties...

  8. New Concepts in Instrumentation Development to Measure the Perry Scheme.

    ERIC Educational Resources Information Center

    Taylor, Marcia

    The Perry scheme of intellectual and ethical development has become widely used in a range of academic disciplines and such areas as career training and faculty consultation. However, current measurement techniques for the scheme, whether interview format or paper and pencil measures, do not adequately address issues related to assessing cognitive…

  9. A modified symplectic PRK scheme for seismic wave modeling

    NASA Astrophysics Data System (ADS)

    Liu, Shaolin; Yang, Dinghui; Ma, Jian

    2017-02-01

    A new scheme for the temporal discretization of the seismic wave equation is constructed based on symplectic geometric theory and a modified strategy. The ordinary differential equation in terms of time, which is obtained after spatial discretization via the spectral-element method, is transformed into a Hamiltonian system. A symplectic partitioned Runge-Kutta (PRK) scheme is used to solve the Hamiltonian system. A term related to the multiplication of the spatial discretization operator with the seismic wave velocity vector is added into the symplectic PRK scheme to create a modified symplectic PRK scheme. The symplectic coefficients of the new scheme are determined via Taylor series expansion. The positive coefficients of the scheme indicate that its long-term computational capability is more powerful than that of conventional symplectic schemes. An exhaustive theoretical analysis reveals that the new scheme is highly stable and has low numerical dispersion. The results of three numerical experiments demonstrate the high efficiency of this method for seismic wave modeling.

  10. State of the Art in the Cramer Classification Scheme and ...

    EPA Pesticide Factsheets

    Slide presentation at the SOT FDA Colloquium on State of the Art in the Cramer Classification Scheme and Threshold of Toxicological Concern in College Park, MD. Slide presentation at the SOT FDA Colloquium on State of the Art in the Cramer Classification Scheme and Threshold of Toxicological Concern in College Park, MD.

  11. A Scale of Cognitive Development: Validating Perry's Scheme.

    ERIC Educational Resources Information Center

    Fago, George C.

    When William G. Perry (1968) developed his scheme of nine stages of cognitive development, most of which are experienced during the college years, he did not attempt to quantify it. Subsequently, T. D. Erwin (1983) constructed a scale that attempted to quantify the Perry scheme. His findings supported the overall conception of student development…

  12. An improved SPH scheme for cosmological simulations

    NASA Astrophysics Data System (ADS)

    Beck, A. M.; Murante, G.; Arth, A.; Remus, R.-S.; Teklu, A. F.; Donnert, J. M. F.; Planelles, S.; Beck, M. C.; Förster, P.; Imgrund, M.; Dolag, K.; Borgani, S.

    2016-01-01

    We present an implementation of smoothed particle hydrodynamics (SPH) with improved accuracy for simulations of galaxies and the large-scale structure. In particular, we implement and test a vast majority of SPH improvement in the developer version of GADGET-3. We use the Wendland kernel functions, a particle wake-up time-step limiting mechanism and a time-dependent scheme for artificial viscosity including high-order gradient computation and shear flow limiter. Additionally, we include a novel prescription for time-dependent artificial conduction, which corrects for gravitationally induced pressure gradients and improves the SPH performance in capturing the development of gas-dynamical instabilities. We extensively test our new implementation in a wide range of hydrodynamical standard tests including weak and strong shocks as well as shear flows, turbulent spectra, gas mixing, hydrostatic equilibria and self-gravitating gas clouds. We jointly employ all modifications; however, when necessary we study the performance of individual code modules. We approximate hydrodynamical states more accurately and with significantly less noise than standard GADGET-SPH. Furthermore, the new implementation promotes the mixing of entropy between different fluid phases, also within cosmological simulations. Finally, we study the performance of the hydrodynamical solver in the context of radiative galaxy formation and non-radiative galaxy cluster formation. We find galactic discs to be colder and more extended and galaxy clusters showing entropy cores instead of steadily declining entropy profiles. In summary, we demonstrate that our improved SPH implementation overcomes most of the undesirable limitations of standard GADGET-SPH, thus becoming the core of an efficient code for large cosmological simulations.

  13. A privacy enhanced authentication scheme for telecare medical information systems.

    PubMed

    Jiang, Qi; Ma, Jianfeng; Ma, Zhuo; Li, Guangsong

    2013-02-01

    The telecare medical information system (TMIS) aims to establish telecare services and enable the public to access medical services or medical information at remote sites. Authentication and key agreement is essential to ensure data integrity, confidentiality, and availability for TMIS. Most recently, Chen et al. proposed an efficient and secure dynamic ID-based authentication scheme for TMIS, and claimed that their scheme achieves user anonymity. However, we observe that Chen et al.'s scheme achieves neither anonymity nor untraceability, and is subject to the identity guessing attack and tracking attack. In order to protect user privacy, we propose an enhanced authentication scheme which achieves user anonymity and untraceablity. It is a secure and efficient authentication scheme with user privacy preservation which is practical for TMIS.

  14. A Secure and Efficient Threshold Group Signature Scheme

    NASA Astrophysics Data System (ADS)

    Zhang, Yansheng; Wang, Xueming; Qiu, Gege

    The paper presents a secure and efficient threshold group signature scheme aiming at two problems of current threshold group signature schemes: conspiracy attack and inefficiency. Scheme proposed in this paper takes strategy of separating designed clerk who is responsible for collecting and authenticating each individual signature from group, the designed clerk don't participate in distribution of group secret key and has his own public key and private key, designed clerk needs to sign part information of threshold group signature after collecting signatures. Thus verifier has to verify signature of the group after validating signature of the designed clerk. This scheme is proved to be secure against conspiracy attack at last and is more efficient by comparing with other schemes.

  15. On Approximate Factorization Schemes for Solving the Full Potential Equation

    NASA Technical Reports Server (NTRS)

    Holst, Terry L.

    1997-01-01

    An approximate factorization scheme based on the AF2 algorithm is presented for solving the three-dimensional full potential equation for the transonic flow about isolated wings. Two spatial discretization variations are presented, one using a hybrid first-order/second-order-accurate scheme and the second using a fully second-order-accurate scheme. The present algorithm utilizes a C-H grid topology to map the flow field about the wing. One version of the AF2 iteration scheme is used on the upper wing surface and another slightly modified version is used on the lower surface. These two algorithm variations are then connected at the wing leading edge using a local iteration technique. The resulting scheme has improved linear stability characteristics and improved time-like damping characteristics relative to previous implementations of the AF2 algorithm. The presentation is highlighted with a grid refinement study and a number of numerical results.

  16. A new antiproton beam transfer scheme without coalescing

    SciTech Connect

    Weiren Chou et al.

    2003-06-04

    An effective way to increase the luminosity in the Fermilab Tevatron collider program Run2 is to improve the overall antiproton transfer efficiency. During antiproton coalescing in the Main Injector (MI), about 10-15% particles get lost. This loss could be avoided in a new antiproton transfer scheme that removes coalescing from the process. Moreover, this scheme would also eliminate emittance dilution due to coalescing. This scheme uses a 2.5 MHz RF system to transfer antiprotons from the Accumulator to the Main Injector. It is then followed by a bunch rotation in the MI to shorten the bunch length so that it can be captured by a 53 MHz RF bucket. Calculations and ESME simulations show that this scheme works. No new hardware is needed to implement this scheme.

  17. Improved-efficiency DSMC collision-partner selection schemes.

    SciTech Connect

    Gallis, Michail A.; Torczynski, John Robert

    2010-11-01

    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.

  18. Factorizable Upwind Schemes: The Triangular Unstructured Grid Formulation

    NASA Technical Reports Server (NTRS)

    Sidilkover, David; Nielsen, Eric J.

    2001-01-01

    The upwind factorizable schemes for the equations of fluid were introduced recently. They facilitate achieving the Textbook Multigrid Efficiency (TME) and are expected also to result in the solvers of unparalleled robustness. The approach itself is very general. Therefore, it may well become a general framework for the large-scale, Computational Fluid Dynamics. In this paper we outline the triangular grid formulation of the factorizable schemes. The derivation is based on the fact that the factorizable schemes can be expressed entirely using vector notation. without explicitly mentioning a particular coordinate frame. We, describe the resulting discrete scheme in detail and present some computational results verifying the basic properties of the scheme/solver.

  19. A Proxy Signature Scheme Based on Coding Theory

    NASA Astrophysics Data System (ADS)

    Jannati, Hoda; Falahati, Abolfazl

    Proxy signature helps the proxy signer to sign messages on behalf of the original signer. This signature is used when the original signer is not available to sign a specific document. In this paper, we introduce a new proxy signature scheme based on Stern's identification scheme whose security depends on syndrome decoding problem. The proposed scheme is the first code-based proxy signature and can be used in a quantum computer. In this scheme, the operations to perform are linear and very simple thus the signature is performed quickly and can be implemented using smart card in a quite efficient way. The proposed scheme also satisfies unforgeability, undeniability, non-transferability and distinguishability properties which are the security requirements for a proxy signature.

  20. An Anonymous Voting Scheme based on Confirmation Numbers

    NASA Astrophysics Data System (ADS)

    Alam, Kazi Md. Rokibul; Tamura, Shinsuke; Taniguchi, Shuji; Yanase, Tatsuro

    This paper proposes a new electronic voting (e-voting) scheme that fulfills all the security requirements of e-voting i.e. privacy, accuracy, universal verifiability, fairness, receipt-freeness, incoercibility, dispute-freeness, robustness, practicality and scalability; usually some of which are found to be traded. When compared with other existing schemes, this scheme requires much more simple computations and weaker assumptions about trustworthiness of individual election authorities. The key mechanism is the one that uses confirmation numbers involved in individual votes to make votes verifiable while disabling all entities including voters themselves to know the linkages between voters and their votes. Many existing e-voting schemes extensively deploy zero-knowledge proof (ZKP) to achieve verifiability. However, ZKP is expensive and complicated. The confirmation numbers attain the verifiability requirement in a much more simple and intuitive way, then the scheme becomes scalable and practical.

  1. Validation of Microphysical Schemes in a CRM Using TRMM Satellite

    NASA Astrophysics Data System (ADS)

    Li, X.; Tao, W.; Matsui, T.; Liu, C.; Masunaga, H.

    2007-12-01

    The microphysical scheme in the Goddard Cumulus Ensemble (GCE) model has been the most heavily developed component in the past decade. The cloud-resolving model now has microphysical schemes ranging from the original Lin type bulk scheme, to improved bulk schemes, to a two-moment scheme, to a detailed bin spectral scheme. Even with the most sophisticated bin scheme, many uncertainties still exist, especially in ice phase microphysics. In this study, we take advantages of the long-term TRMM observations, especially the cloud profiles observed by the precipitation radar (PR), to validate microphysical schemes in the simulations of Mesoscale Convective Systems (MCSs). Two contrasting cases, a midlatitude summertime continental MCS with leading convection and trailing stratiform region, and an oceanic MCS in tropical western Pacific are studied. The simulated cloud structures and particle sizes are fed into a forward radiative transfer model to simulate the TRMM satellite sensors, i.e., the PR, the TRMM microwave imager (TMI) and the visible and infrared scanner (VIRS). MCS cases that match the structure and strength of the simulated systems over the 10-year period are used to construct statistics of different sensors. These statistics are then compared with the synthetic satellite data obtained from the forward radiative transfer calculations. It is found that the GCE model simulates the contrasts between the continental and oceanic case reasonably well, with less ice scattering in the oceanic case comparing with the continental case. However, the simulated ice scattering signals for both PR and TMI are generally stronger than the observations, especially for the bulk scheme and at the upper levels in the stratiform region. This indicates larger, denser snow/graupel particles at these levels. Adjusting microphysical schemes in the GCE model according the observations, especially the 3D cloud structure observed by TRMM PR, result in a much better agreement.

  2. Completely anonymous multi-recipient signcryption scheme with public verification.

    PubMed

    Pang, Liaojun; Li, Huixian; Gao, Lu; Wang, Yumin

    2013-01-01

    Most of the existing multi-recipient signcryption schemes do not take the anonymity of recipients into consideration because the list of the identities of all recipients must be included in the ciphertext as a necessary element for decryption. Although the signer's anonymity has been taken into account in several alternative schemes, these schemes often suffer from the cross-comparison attack and joint conspiracy attack. That is to say, there are few schemes that can achieve complete anonymity for both the signer and the recipient. However, in many practical applications, such as network conference, both the signer's and the recipient's anonymity should be considered carefully. Motivated by these concerns, we propose a novel multi-recipient signcryption scheme with complete anonymity. The new scheme can achieve both the signer's and the recipient's anonymity at the same time. Each recipient can easily judge whether the received ciphertext is from an authorized source, but cannot determine the real identity of the sender, and at the same time, each participant can easily check decryption permission, but cannot determine the identity of any other recipient. The scheme also provides a public verification method which enables anyone to publicly verify the validity of the ciphertext. Analyses show that the proposed scheme is more efficient in terms of computation complexity and ciphertext length and possesses more advantages than existing schemes, which makes it suitable for practical applications. The proposed scheme could be used for network conferences, paid-TV or DVD broadcasting applications to solve the secure communication problem without violating the privacy of each participant.

  3. Completely Anonymous Multi-Recipient Signcryption Scheme with Public Verification

    PubMed Central

    Pang, Liaojun; Li, Huixian; Gao, Lu; Wang, Yumin

    2013-01-01

    Most of the existing multi-recipient signcryption schemes do not take the anonymity of recipients into consideration because the list of the identities of all recipients must be included in the ciphertext as a necessary element for decryption. Although the signer’s anonymity has been taken into account in several alternative schemes, these schemes often suffer from the cross-comparison attack and joint conspiracy attack. That is to say, there are few schemes that can achieve complete anonymity for both the signer and the recipient. However, in many practical applications, such as network conference, both the signer’s and the recipient’s anonymity should be considered carefully. Motivated by these concerns, we propose a novel multi-recipient signcryption scheme with complete anonymity. The new scheme can achieve both the signer’s and the recipient’s anonymity at the same time. Each recipient can easily judge whether the received ciphertext is from an authorized source, but cannot determine the real identity of the sender, and at the same time, each participant can easily check decryption permission, but cannot determine the identity of any other recipient. The scheme also provides a public verification method which enables anyone to publicly verify the validity of the ciphertext. Analyses show that the proposed scheme is more efficient in terms of computation complexity and ciphertext length and possesses more advantages than existing schemes, which makes it suitable for practical applications. The proposed scheme could be used for network conferences, paid-TV or DVD broadcasting applications to solve the secure communication problem without violating the privacy of each participant. Key words: Multi-recipient signcryption; Signcryption; Complete Anonymity; Public verification. PMID:23675490

  4. A class of the van Leer-type transport schemes and its application to the moisture transport in a general circulation model

    SciTech Connect

    Lin, Shian-Jiann; Chao, W.C.; Sud, Y.C.; Walker, G.K. )

    1994-07-01

    A generalized form of the second-order van Leer transport scheme is derived. Several constraints to the implied subgrid linear distribution are discussed. A very simple positive-definite scheme can be derived directly from the generalized form. A monotonic version of these scheme is applied to the Goddard Laboratory for Atmospheres (GLA) general circulation model (GCM) for the moisture transport calculations, replacing the original fourth-order center-differencing scheme. Comparisons with the original scheme are made in idealized tests as well as in a summer climate simulation using the full GLA GCM. A distinct advantage of the monotonic transport scheme is its ability to transport sharp gradients without producing spurious oscillations and unphysical negative mixing ratio. Within the context of low-resolution climate simulations, the aforementioned characteristics are demonstrated to be very beneficial in regions where cumulus convection is active. The model-produced precipitation pattern using the new transport scheme is more coherently organized both in time and in space, and correlates better with observations. The side effect of the filling algorithm used in conjunction with the original scheme is also discussed, in the context of idealized tests. The major weakness of the proposed transport scheme with a local monotonic constraint is its substantial implicit diffusion at low resolution. Alternative constraints are discussed to counter this problem. 34 refs., 13 figs., 1 tab.

  5. A class of the van Leer-type transport schemes and its application to the moisture transport in a general circulation model

    NASA Technical Reports Server (NTRS)

    Lin, Shian-Jiann; Chao, Winston C.; Sud, Y. C.; Walker, G. K.

    1994-01-01

    A generalized form of the second-order van Leer transport scheme is derived. Several constraints to the implied subgrid linear distribution are discussed. A very simple positive-definite scheme can be derived directly from the generalized form. A monotonic version of the scheme is applied to the Goddard Laboratory for Atmospheres (GLA) general circulation model (GCM) for the moisture transport calculations, replacing the original fourth-order center-differencing scheme. Comparisons with the original scheme are made in idealized tests as well as in a summer climate simulation using the full GLA GCM. A distinct advantage of the monotonic transport scheme is its ability to transport sharp gradients without producing spurious oscillations and unphysical negative mixing ratio. Within the context of low-resolution climate simulations, the aforementioned characteristics are demonstrated to be very beneficial in regions where cumulus convection is active. The model-produced precipitation pattern using the new transport scheme is more coherently organized both in time and in space, and correlates better with observations. The side effect of the filling algorithm used in conjunction with the original scheme is also discussed, in the context of idealized tests. The major weakness of the proposed transport scheme with a local monotonic constraint is its substantial implicit diffusion at low resolution. Alternative constraints are discussed to counter this problem.

  6. The effects of residual platelets in plasma on plasminogen activator inhibitor-1 and plasminogen activator inhibitor-1-related assays

    PubMed Central

    Barnard, Sunelle A.; Loots, Du Toit; Rijken, Dingeman C.

    2017-01-01

    Due to controversial evidence in the literature pertaining to the activity of plasminogen activator inhibitor-1 in platelets, we examined the effects of residual platelets present in plasma (a potential pre-analytical variable) on various plasminogen activator inhibitor-1 and plasminogen activator inhibitor-1-related assays. Blood samples were collected from 151 individuals and centrifuged at 352 and 1500 g to obtain plasma with varying numbers of platelet. In a follow-up study, blood samples were collected from an additional 23 individuals, from whom platelet-poor (2000 g), platelet-containing (352 g) and platelet-rich plasma (200 g) were prepared and analysed as fresh-frozen and after five defrost-refreeze cycles (to determine the contribution of in vitro platelet degradation). Plasminogen activator inhibitor-1 activity, plasminogen activator inhibitor-1 antigen, tissue plasminogen activator/plasminogen activator inhibitor-1 complex, plasma clot lysis time, β-thromboglobulin and plasma platelet count were analysed. Platelet α-granule release (plasma β-thromboglobulin) showed a significant association with plasminogen activator inhibitor-1 antigen levels but weak associations with plasminogen activator inhibitor-1 activity and a functional marker of fibrinolysis, clot lysis time. Upon dividing the study population into quartiles based on β-thromboglobulin levels, plasminogen activator inhibitor-1 antigen increased significantly across the quartiles while plasminogen activator inhibitor-1 activity and clot lysis time tended to increase in the 4th quartile only. In the follow-up study, plasma plasminogen activator inhibitor-1 antigen was also significantly influenced by platelet count in a concentration-dependent manner. Plasma plasminogen activator inhibitor-1 antigen levels increased further after complete platelet degradation. Residual platelets in plasma significantly influence plasma plasminogen activator inhibitor-1 antigen levels mainly through release of

  7. An efficient class of WENO schemes with adaptive order

    NASA Astrophysics Data System (ADS)

    Balsara, Dinshaw S.; Garain, Sudip; Shu, Chi-Wang

    2016-12-01

    Finite difference WENO schemes have established themselves as very worthy performers for entire classes of applications that involve hyperbolic conservation laws. In this paper we report on two major advances that make finite difference WENO schemes more efficient. The first advance consists of realizing that WENO schemes require us to carry out stencil operations very efficiently. In this paper we show that the reconstructed polynomials for any one-dimensional stencil can be expressed most efficiently and economically in Legendre polynomials. By using Legendre basis, we show that the reconstruction polynomials and their corresponding smoothness indicators can be written very compactly. The smoothness indicators are written as a sum of perfect squares. Since this is a computationally expensive step, the efficiency of finite difference WENO schemes is enhanced by the innovation which is reported here. The second advance consists of realizing that one can make a non-linear hybridization between a large, centered, very high accuracy stencil and a lower order WENO scheme that is nevertheless very stable and capable of capturing physically meaningful extrema. This yields a class of adaptive order WENO schemes, which we call WENO-AO (for adaptive order). Thus we arrive at a WENO-AO(5,3) scheme that is at best fifth order accurate by virtue of its centered stencil with five zones and at worst third order accurate by virtue of being non-linearly hybridized with an r = 3 CWENO scheme. The process can be extended to arrive at a WENO-AO(7,3) scheme that is at best seventh order accurate by virtue of its centered stencil with seven zones and at worst third order accurate. We then recursively combine the above two schemes to arrive at a WENO-AO(7,5,3) scheme which can achieve seventh order accuracy when that is possible; graciously drop down to fifth order accuracy when that is the best one can do; and also operate stably with an r = 3 CWENO scheme when that is the only thing

  8. A modified F/A-18A sporting a distinctive red, white and blue paint scheme is the test aircraft for

    NASA Technical Reports Server (NTRS)

    2001-01-01

    A modified F/A-18A sporting a distinctive red, white and blue paint scheme is the test aircraft for the Active Aeroelastic Wing (AAW) project at NASA's Dryden Flight Research Center, Edwards, California.

  9. This modified F/A-18A with its distinctive red, white and blue paint scheme is the test aircraft for

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This modified F/A-18A with its distinctive red, white and blue paint scheme is the test aircraft for the Active Aeroelastic Wing (AAW) project at NASA's Dryden Flight Research Center, Edwards, California.

  10. Signal processing schemes for optical voltage transducer

    NASA Astrophysics Data System (ADS)

    Chen, Jinling; Xie, Delin; Chen, Hongbin; Xie, Latang; Song, Jianhe; Luo, Xiaoni

    2006-02-01

    This paper describes an optical voltage transducer(OVT) for a 35kV system based on Pockels effect in a BGO(Bi 4Ge 3O 12) crystal. OVT used to measure the voltage of power are superior to conventional electromagnet-induced voltage transducer in many aspects, thus it has great potential to applications. It has some advantages. These advantages are: 1)Optics provides total galvanic separation between the measuring point at high voltage (HV) potential and the measuring equipment at ground potential. 2)Transmission of measuring signals in optical fibers is immune to induced electromagnetic noise even in EMI-environment of switchyards and other high voltage installations. 3)Optics and especially optical fibers make the insulation costs independent of voltage levels thus giving an economical advantage at voltage levels above 100kV. 4)The use of optics is expected to reduce the weight of the transducers. 5)Optical transducers are expected to have a large bandwidth than conventional transducers. 6)The output-signals from an optical transducer are easily interfaced with computers and electronically operated equipment such as digital relays. New techniques developed in electronics and optical field including fiber optic technology bring new contributions to the measurement of voltage and electric field. A Pockels voltage sensor has been widely introduced to electrical power transmission and distribution systems and some advantage of the optical voltage measuring techniques are reported. In this paper, a brief summary of electro-optic effects and the principle of OVT is proposed. The signal processing schemes of different optical path and features are analyzed. The basic principle of OVT is to modulate the irradiance of the light-directed to OVT by an optical fiber-according to the potential difference between the HV-line and the ground potential. The modulation of the light is accomplished by placing a material-that has an optical property (the birefringence), which is

  11. Key Management Scheme Based on Route Planning of Mobile Sink in Wireless Sensor Networks

    PubMed Central

    Zhang, Ying; Liang, Jixing; Zheng, Bingxin; Jiang, Shengming; Chen, Wei

    2016-01-01

    In many wireless sensor network application scenarios the key management scheme with a Mobile Sink (MS) should be fully investigated. This paper proposes a key management scheme based on dynamic clustering and optimal-routing choice of MS. The concept of Traveling Salesman Problem with Neighbor areas (TSPN) in dynamic clustering for data exchange is proposed, and the selection probability is used in MS route planning. The proposed scheme extends static key management to dynamic key management by considering the dynamic clustering and mobility of MSs, which can effectively balance the total energy consumption during the activities. Considering the different resources available to the member nodes and sink node, the session key between cluster head and MS is established by modified an ECC encryption with Diffie-Hellman key exchange (ECDH) algorithm and the session key between member node and cluster head is built with a binary symmetric polynomial. By analyzing the security of data storage, data transfer and the mechanism of dynamic key management, the proposed scheme has more advantages to help improve the resilience of the key management system of the network on the premise of satisfying higher connectivity and storage efficiency. PMID:26840311

  12. Exact density functional and wave function embedding schemes based on orbital localization

    NASA Astrophysics Data System (ADS)

    Hégely, Bence; Nagy, Péter R.; Ferenczy, György G.; Kállay, Mihály

    2016-08-01

    Exact schemes for the embedding of density functional theory (DFT) and wave function theory (WFT) methods into lower-level DFT or WFT approaches are introduced utilizing orbital localization. First, a simple modification of the projector-based embedding scheme of Manby and co-workers [J. Chem. Phys. 140, 18A507 (2014)] is proposed. We also use localized orbitals to partition the system, but instead of augmenting the Fock operator with a somewhat arbitrary level-shift projector we solve the Huzinaga-equation, which strictly enforces the Pauli exclusion principle. Second, the embedding of WFT methods in local correlation approaches is studied. Since the latter methods split up the system into local domains, very simple embedding theories can be defined if the domains of the active subsystem and the environment are treated at a different level. The considered embedding schemes are benchmarked for reaction energies and compared to quantum mechanics (QM)/molecular mechanics (MM) and vacuum embedding. We conclude that for DFT-in-DFT embedding, the Huzinaga-equation-based scheme is more efficient than the other approaches, but QM/MM or even simple vacuum embedding is still competitive in particular cases. Concerning the embedding of wave function methods, the clear winner is the embedding of WFT into low-level local correlation approaches, and WFT-in-DFT embedding can only be more advantageous if a non-hybrid density functional is employed.

  13. Automated scheme for measuring mandibular cortical thickness on dental panoramic radiographs for osteoporosis screening

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.; Hayashi, T.; Hara, T.; Katsumata, A.; Muramatsu, C.; Zhou, X.; Iida, Y.; Matsuoka, M.; Katagi, Ki.; Fujita, H.

    2012-03-01

    Findings of dental panoramic radiographs (DPRs) have shown that the mandibular cortical thickness (MCT) was significantly correlated with osteoporosis. Identifying asymptomatic patients with osteoporosis through dental examinations may bring a supplemental benefit for the patients. However, most of the DPRs are used for only diagnosing dental conditions by dentists in their routine clinical work. The aim of this study was to develop a computeraided diagnosis scheme that automatically measures MCT to assist dentists in screening osteoporosis. First, the inferior border of mandibular bone was detected by use of an active contour method. Second, the locations of mental foramina were estimated on the basis of the inferior border of mandibular bone. Finally, MCT was measured on the basis of the grayscale profile analysis. One hundred DPRs were used to evaluate our proposed scheme. Experimental results showed that the sensitivity and specificity for identifying osteoporotic patients were 92.6 % and 100 %, respectively. We conducted multiclinic trials, in which 223 cases have been obtained and processed in about a month. Our scheme succeeded in detecting all cases of suspected osteoporosis. Therefore, our scheme may have a potential to identify osteoporotic patients at an early stage.

  14. Key Management Scheme Based on Route Planning of Mobile Sink in Wireless Sensor Networks.

    PubMed

    Zhang, Ying; Liang, Jixing; Zheng, Bingxin; Jiang, Shengming; Chen, Wei

    2016-01-29

    In many wireless sensor network application scenarios the key management scheme with a Mobile Sink (MS) should be fully investigated. This paper proposes a key management scheme based on dynamic clustering and optimal-routing choice of MS. The concept of Traveling Salesman Problem with Neighbor areas (TSPN) in dynamic clustering for data exchange is proposed, and the selection probability is used in MS route planning. The proposed scheme extends static key management to dynamic key management by considering the dynamic clustering and mobility of MSs, which can effectively balance the total energy consumption during the activities. Considering the different resources available to the member nodes and sink node, the session key between cluster head and MS is established by modified an ECC encryption with Diffie-Hellman key exchange (ECDH) algorithm and the session key between member node and cluster head is built with a binary symmetric polynomial. By analyzing the security of data storage, data transfer and the mechanism of dynamic key management, the proposed scheme has more advantages to help improve the resilience of the key management system of the network on the premise of satisfying higher connectivity and storage efficiency.

  15. A novel scheme of signaling protocol based on mobile agent and OBS

    NASA Astrophysics Data System (ADS)

    Mao, Minjing; Liu, Deming; Li, Wei

    2005-11-01

    A novel scheme of signaling protocol based on mobile agent and OBS which runs over a core DWDM network is promoted. Design of optical wavelength channels in the scheme is to choose 1310nm band to be control optical wavelength channel to transmit BHPs and 1550nm band to be burst packets optical wavelength channels to transmit BPs. Referring to RSVP-TE in DCM ASON, significations and formats of signaling messages in the protocol are defined. The key design of scheme is to utilize the structure of active packets in the application of mobile agent MANet to encapsulate signaling messages and traffic together into one BHP to shorten the set-up time of an optical path. Such structure is also used to process distributed disposals to alleviate the workload of one node in the network to promote cooperating calculation ability of each node in the network. The communication between a source node and a destination node through one or multiple intermediate nodes is presented as an example to describe the processing procedures of the protocol. The scheme is implemented in a wavelength router, which is briefly introduced.

  16. Generalized energy and potential enstrophy conserving finite difference schemes for the shallow water equations

    NASA Technical Reports Server (NTRS)

    Abramopoulos, Frank

    1988-01-01

    The conditions under which finite difference schemes for the shallow water equations can conserve both total energy and potential enstrophy are considered. A method of deriving such schemes using operator formalism is developed. Several such schemes are derived for the A-, B- and C-grids. The derived schemes include second-order schemes and pseudo-fourth-order schemes. The simplest B-grid pseudo-fourth-order schemes are presented.

  17. A Novel Multi-Receiver Signcryption Scheme with Complete Anonymity.

    PubMed

    Pang, Liaojun; Yan, Xuxia; Zhao, Huiyang; Hu, Yufei; Li, Huixian

    2016-01-01

    Anonymity, which is more and more important to multi-receiver schemes, has been taken into consideration by many researchers recently. To protect the receiver anonymity, in 2010, the first multi-receiver scheme based on the Lagrange interpolating polynomial was proposed. To ensure the sender's anonymity, the concept of the ring signature was proposed in 2005, but afterwards, this scheme was proven to has some weakness and at the same time, a completely anonymous multi-receiver signcryption scheme is proposed. In this completely anonymous scheme, the sender anonymity is achieved by improving the ring signature, and the receiver anonymity is achieved by also using the Lagrange interpolating polynomial. Unfortunately, the Lagrange interpolation method was proven a failure to protect the anonymity of receivers, because each authorized receiver could judge whether anyone else is authorized or not. Therefore, the completely anonymous multi-receiver signcryption mentioned above can only protect the sender anonymity. In this paper, we propose a new completely anonymous multi-receiver signcryption scheme with a new polynomial technology used to replace the Lagrange interpolating polynomial, which can mix the identity information of receivers to save it as a ciphertext element and prevent the authorized receivers from verifying others. With the receiver anonymity, the proposed scheme also owns the anonymity of the sender at the same time. Meanwhile, the decryption fairness and public verification are also provided.

  18. Payment schemes and cost efficiency: evidence from Swiss public hospitals.

    PubMed

    Meyer, Stefan

    2015-03-01

    This paper aims at analysing the impact of prospective payment schemes on cost efficiency of acute care hospitals in Switzerland. We study a panel of 121 public hospitals subject to one of four payment schemes. While several hospitals are still reimbursed on a per diem basis for the treatment of patients, most face flat per-case rates-or mixed schemes, which combine both elements of reimbursement. Thus, unlike previous studies, we are able to simultaneously analyse and isolate the cost-efficiency effects of different payment schemes. By means of stochastic frontier analysis, we first estimate a hospital cost frontier. Using the two-stage approach proposed by Battese and Coelli (Empir Econ 20:325-332, 1995), we then analyse the impact of these payment schemes on the cost efficiency of hospitals. Controlling for hospital characteristics, local market conditions in the 26 Swiss states (cantons), and a time trend, we show that, compared to per diem, hospitals which are reimbursed by flat payment schemes perform better in terms of cost efficiency. Our results suggest that mixed schemes create incentives for cost containment as well, although to a lesser extent. In addition, our findings indicate that cost-efficient hospitals are primarily located in cantons with competitive markets, as measured by the Herfindahl-Hirschman index in inpatient care. Furthermore, our econometric model shows that we obtain biased estimates from frontier analysis if we do not account for heteroscedasticity in the inefficiency term.

  19. Optimised prefactored compact schemes for linear wave propagation phenomena

    NASA Astrophysics Data System (ADS)

    Rona, A.; Spisso, I.; Hall, E.; Bernardini, M.; Pirozzoli, S.

    2017-01-01

    A family of space- and time-optimised prefactored compact schemes are developed that minimise the computational cost for given levels of numerical error in wave propagation phenomena, with special reference to aerodynamic sound. This work extends the approach of Pirozzoli [1] to the MacCormack type prefactored compact high-order schemes developed by Hixon [2], in which their shorter Padé stencil from the prefactorisation leads to a simpler enforcement of numerical boundary conditions. An explicit low-storage multi-step Runge-Kutta integration advances the states in time. Theoretical predictions for spatial and temporal error bounds are derived for the cost-optimised schemes and compared against benchmark schemes of current use in computational aeroacoustic applications in terms of computational cost for a given relative numerical error value. One- and two-dimensional test cases are presented to examine the effectiveness of the cost-optimised schemes for practical flow computations. An effectiveness up to about 50% higher than the standard schemes is verified for the linear one-dimensional advection solver, which is a popular baseline solver kernel for computational physics problems. A substantial error reduction for a given cost is also obtained in the more complex case of a two-dimensional acoustic pulse propagation, provided the optimised schemes are made to operate close to their nominal design points.

  20. Upwind schemes and bifurcating solutions in real gas computations

    NASA Technical Reports Server (NTRS)

    Suresh, Ambady; Liou, Meng-Sing

    1992-01-01

    The area of high speed flow is seeing a renewed interest due to advanced propulsion concepts such as the National Aerospace Plane (NASP), Space Shuttle, and future civil transport concepts. Upwind schemes to solve such flows have become increasingly popular in the last decade due to their excellent shock capturing properties. In the first part of this paper the authors present the extension of the Osher scheme to equilibrium and non-equilibrium gases. For simplicity, the source terms are treated explicitly. Computations based on the above scheme are presented to demonstrate the feasibility, accuracy and efficiency of the proposed scheme. One of the test problems is a Chapman-Jouguet detonation problem for which numerical solutions have been known to bifurcate into spurious weak detonation solutions on coarse grids. Results indicate that the numerical solution obtained depends both on the upwinding scheme used and the limiter employed to obtain second order accuracy. For example, the Osher scheme gives the correct CJ solution when the super-bee limiter is used, but gives the spurious solution when the Van Leer limiter is used. With the Roe scheme the spurious solution is obtained for all limiters.

  1. Study on the numerical schemes for hypersonic flow simulation

    NASA Astrophysics Data System (ADS)

    Nagdewe, S. P.; Shevare, G. R.; Kim, Heuy-Dong

    2009-10-01

    Hypersonic flow is full of complex physical and chemical processes, hence its investigation needs careful analysis of existing schemes and choosing a suitable scheme or designing a brand new scheme. The present study deals with two numerical schemes Harten, Lax, and van Leer with Contact (HLLC) and advection upstream splitting method (AUSM) to effectively simulate hypersonic flow fields, and accurately predict shock waves with minimal diffusion. In present computations, hypersonic flows have been modeled as a system of hyperbolic equations with one additional equation for non-equilibrium energy and relaxing source terms. Real gas effects, which appear typically in hypersonic flows, have been simulated through energy relaxation method. HLLC and AUSM methods are modified to incorporate the conservation laws for non-equilibrium energy. Numerical implementation have shown that non-equilibrium energy convect with mass, and hence has no bearing on the basic numerical scheme. The numerical simulation carried out shows good comparison with experimental data available in literature. Both numerical schemes have shown identical results at equilibrium. Present study has demonstrated that real gas effects in hypersonic flows can be modeled through energy relaxation method along with either AUSM or HLLC numerical scheme.

  2. Efficient Non-interactive Universally Composable String-Commitment Schemes

    NASA Astrophysics Data System (ADS)

    Nishimaki, Ryo; Fujisaki, Eiichiro; Tanaka, Keisuke

    The universal composability (UC) for commitment is a very strong security notion. It guarantees that commitment schemes remain secure even if they are composed with arbitrary protocols and polynomially many copies of the schemes are run concurrently. Several UC commitment schemes in the common reference string (CRS) model have been proposed, but, they are either interactive commitment or bit-commitment (not string-commitment) schemes. We propose new non-interactive string-commitment schemes that achieve UC security in the CRS model assuming the difficulty of the decisional Diffie-Hellman problem or the decisional composite residuosity problem, but our schemes are not reusable. The main building blocks of our constructions are all-but-one trapdoor functions (ABO-TDFs) introduced by Peikert and Waters in STOC 2008 to construct secure public-key encryption schemes. Our main idea is to use the homomorphic properties of the function indices of the all-but-one trapdoor functions and to extend the functions to probabilistic ones by using re-randomization of ciphertexts. This is a new application of ABO-TDFs.

  3. A Novel Multi-Receiver Signcryption Scheme with Complete Anonymity

    PubMed Central

    Pang, Liaojun; Yan, Xuxia; Zhao, Huiyang; Hu, Yufei; Li, Huixian

    2016-01-01

    Anonymity, which is more and more important to multi-receiver schemes, has been taken into consideration by many researchers recently. To protect the receiver anonymity, in 2010, the first multi-receiver scheme based on the Lagrange interpolating polynomial was proposed. To ensure the sender’s anonymity, the concept of the ring signature was proposed in 2005, but afterwards, this scheme was proven to has some weakness and at the same time, a completely anonymous multi-receiver signcryption scheme is proposed. In this completely anonymous scheme, the sender anonymity is achieved by improving the ring signature, and the receiver anonymity is achieved by also using the Lagrange interpolating polynomial. Unfortunately, the Lagrange interpolation method was proven a failure to protect the anonymity of receivers, because each authorized receiver could judge whether anyone else is authorized or not. Therefore, the completely anonymous multi-receiver signcryption mentioned above can only protect the sender anonymity. In this paper, we propose a new completely anonymous multi-receiver signcryption scheme with a new polynomial technology used to replace the Lagrange interpolating polynomial, which can mix the identity information of receivers to save it as a ciphertext element and prevent the authorized receivers from verifying others. With the receiver anonymity, the proposed scheme also owns the anonymity of the sender at the same time. Meanwhile, the decryption fairness and public verification are also provided. PMID:27832105

  4. Regulatory scheme for noise enforcement in New Jersey

    NASA Astrophysics Data System (ADS)

    Zwerling, Eric M.

    2005-09-01

    In the state of New Jersey, noise control programs exist at the state, county, and municipal levels. The Noise Control Act of 1971 (N.J.S.A.13:1G-1, et seq.) is the enabling legislation for the current statewide scheme of noise regulation, which empowered the New Jersey Department of Environmental Protection (DEP) to ``promulgate codes, rules and regulations'' to control and abate noise. Chapter 29, Noise Control (N.J.A.C. 7:29, et seq.) was adopted in 1974, regulating commercial, industrial, community, and public service facilities. Initially, the DEP conducted field enforcement of the code, but has since delegated the authority primarily to county enforcement programs, pursuant to the County Environmental Health Act (N.J.S.A. 20:3A2-21, et seq.). Local agencies may enforce the state code by agreement with their county or alternatively may adopt the Model Ordinance promulgated by the DEP. The Model Ordinance regulates additional sound sources, including residential, multidwelling and multiuse buildings, and enumerates a list of Restricted Uses and Activities. The state code and Model Ordinance are performance codes which establish specific sound level limits, measured per established protocol. Local jurisdictions lacking the desire or capability of enforcing a performance code may choose to adopt and enforce a more subjective nuisance code.

  5. A rhythm-based authentication scheme for smart media devices.

    PubMed

    Lee, Jae Dong; Jeong, Young-Sik; Park, Jong Hyuk

    2014-01-01

    In recent years, ubiquitous computing has been rapidly emerged in our lives and extensive studies have been conducted in a variety of areas related to smart devices, such as tablets, smartphones, smart TVs, smart refrigerators, and smart media devices, as a measure for realizing the ubiquitous computing. In particular, smartphones have significantly evolved from the traditional feature phones. Increasingly higher-end smartphone models that can perform a range of functions are now available. Smart devices have become widely popular since they provide high efficiency and great convenience for not only private daily activities but also business endeavors. Rapid advancements have been achieved in smart device technologies to improve the end users' convenience. Consequently, many people increasingly rely on smart devices to store their valuable and important data. With this increasing dependence, an important aspect that must be addressed is security issues. Leaking of private information or sensitive business data due to loss or theft of smart devices could result in exorbitant damage. To mitigate these security threats, basic embedded locking features are provided in smart devices. However, these locking features are vulnerable. In this paper, an original security-locking scheme using a rhythm-based locking system (RLS) is proposed to overcome the existing security problems of smart devices. RLS is a user-authenticated system that addresses vulnerability issues in the existing locking features and provides secure confidentiality in addition to convenience.

  6. A Rhythm-Based Authentication Scheme for Smart Media Devices

    PubMed Central

    Lee, Jae Dong; Park, Jong Hyuk

    2014-01-01

    In recent years, ubiquitous computing has been rapidly emerged in our lives and extensive studies have been conducted in a variety of areas related to smart devices, such as tablets, smartphones, smart TVs, smart refrigerators, and smart media devices, as a measure for realizing the ubiquitous computing. In particular, smartphones have significantly evolved from the traditional feature phones. Increasingly higher-end smartphone models that can perform a range of functions are now available. Smart devices have become widely popular since they provide high efficiency and great convenience for not only private daily activities but also business endeavors. Rapid advancements have been achieved in smart device technologies to improve the end users' convenience. Consequently, many people increasingly rely on smart devices to store their valuable and important data. With this increasing dependence, an important aspect that must be addressed is security issues. Leaking of private information or sensitive business data due to loss or theft of smart devices could result in exorbitant damage. To mitigate these security threats, basic embedded locking features are provided in smart devices. However, these locking features are vulnerable. In this paper, an original security-locking scheme using a rhythm-based locking system (RLS) is proposed to overcome the existing security problems of smart devices. RLS is a user-authenticated system that addresses vulnerability issues in the existing locking features and provides secure confidentiality in addition to convenience. PMID:25110743

  7. The sensitivity of warm season quantitative precipitation forecasts to modifications of the Kain-Fritch Convective Parameterization Scheme

    NASA Astrophysics Data System (ADS)

    Mazarakis, N.; Kotroni, V.; Lagouvardos, K.; Argiriou, A.

    2009-09-01

    The sensitivity of quantitative precipitation forecasts to various modifications of the Kain-Fritsch (KF) convective parameterization scheme (CPS) is examined for twenty selected cases characterized by intense convective activity and widespread precipitation over Greece, during the warm period of years 2005-2007. Namely, the study is conducted using MM5 model. The modifications to the KF CPS, each designed to test model sensitivity to the convective scheme formulation, are discussed. The modifications include: (a) the maximization of the convective scheme precipitation efficiency, (b) the change of the convective time step, (c) the force of the convective scheme to produce more/less cloud material, (d) the alteration of the vertical profile of updraft mass flux detrainment. One hundred forty numerical simulations have been carried out on two nested domains, with horizontal grid increments of 24 and 8 km respectively. The simulated precipitation from the 8-km grid is verified against raingauge measurements. Model results using the aforementioned modifications of the convective scheme does not show significant improvements in 6-h precipitations totals compared to simulations generated using the unmodified convective scheme. In general, skill scores among the cases and the precipitation thresholds vary widely.

  8. An efficient quantum scheme for Private Set Intersection

    NASA Astrophysics Data System (ADS)

    Shi, Run-hua; Mu, Yi; Zhong, Hong; Cui, Jie; Zhang, Shun

    2016-01-01

    Private Set Intersection allows a client to privately compute set intersection with the collaboration of the server, which is one of the most fundamental and key problems within the multiparty collaborative computation of protecting the privacy of the parties. In this paper, we first present a cheat-sensitive quantum scheme for Private Set Intersection. Compared with classical schemes, our scheme has lower communication complexity, which is independent of the size of the server's set. Therefore, it is very suitable for big data services in Cloud or large-scale client-server networks.

  9. An Energy Decaying Scheme for Nonlinear Dynamics of Shells

    NASA Technical Reports Server (NTRS)

    Bottasso, Carlo L.; Bauchau, Olivier A.; Choi, Jou-Young; Bushnell, Dennis M. (Technical Monitor)

    2000-01-01

    A novel integration scheme for nonlinear dynamics of geometrically exact shells is developed based on the inextensible director assumption. The new algorithm is designed so as to imply the strict decay of the system total mechanical energy at each time step, and consequently unconditional stability is achieved in the nonlinear regime. Furthermore, the scheme features tunable high frequency numerical damping and it is therefore stiffly accurate. The method is tested for a finite element spatial formulation of shells based on mixed interpolations of strain tensorial components and on a two-parameter representation of director rotations. The robustness of the, scheme is illustrated with the help of numerical examples.

  10. Direct simulations of turbulent flow using finite-difference schemes

    NASA Technical Reports Server (NTRS)

    Rai, Man Mohan; Moin, Parviz

    1989-01-01

    A high-order accurate finite-difference approach is presented for calculating incompressible turbulent flow. The methods used include a kinetic energy conserving central difference scheme and an upwind difference scheme. The methods are evaluated in test cases for the evolution of small-amplitude disturbances and fully developed turbulent channel flow. It is suggested that the finite-difference approach can be applied to complex geometries more easilty than highly accurate spectral methods. It is concluded that the upwind scheme is a good candidate for direct simulations of turbulent flows over complex geometries.

  11. The Implicit and Explicit alpha-mu Schemes

    NASA Technical Reports Server (NTRS)

    Chang, Sin-Chung; Himansu, Ananda

    1997-01-01

    Artificial numerical dissipation is an important issue in large Reynolds number computations. In such computations, the artificial dissipation inherent in traditional numerical schemes can overwhelm the physical dissipation and yield inaccurate results on meshes of practical size. In the present work, the space-time conservation element and solution element method is used to construct new and accurate numerical schemes such that artificial numerical dissipation will not overwhelm physical dissipation. Specifically, these schemes have the property that numerical dissipation vanishes when the physical viscosity goes to zero. These new schemes therefore accurately model the physical dissipation even when it is extremely small. The method of space-time conservation element and solution element, currently under development, is a nontraditional numerical method for solving conservation laws. The method is developed on the basis of local and global flux conservation in a space-time domain, in which space and time are treated in a unified manner. Explicit solvers for model and fluid dynamic conservation laws have previously been investigated. In this paper, we introduce a new concept in the design of implicit schemes, and use it to construct two highly accurate solvers for a convection-diffusion equation. The two schemes become identical in the pure convection case, and in the pure diffusion case. The implicit schemes are applicable over the whole Reynolds number range, from purely diffusive equations to purely inviscid (convective) equations. The stability and consistency of the schemes are analyzed, and some numerical results are presented. It is shown that, in the inviscid case, the new schemes become explicit and their amplification factors are identical to those of the Leapfrog scheme. On the other hand, in the pure diffusion case, their principal amplification factor becomes the amplification factor of the Crank-Nicolson scheme. We also construct an explicit solver

  12. Accuracy of schemes with nonuniform meshes for compressible fluid flows

    NASA Technical Reports Server (NTRS)

    Turkel, E.

    1985-01-01

    The accuracy of the space discretization for time-dependent problems when a nonuniform mesh is used is considered. Many schemes reduce to first-order accuracy while a popular finite volume scheme is even inconsistent for general grids. This accuracy is based on physical variables. However, when accuracy is measured in computational variables then second-order accuracy can be obtained. This is meaningful only if the mesh accurately reflects the properties of the solution. In addition, the stability properties of some improved accurate schemes are analyzed and it can be shown that they also allow for larger time steps when Runge-Kutta type methods are used to advance in time.

  13. Rabies antibody testing and the UK Pet Travel Scheme.

    PubMed

    Fooks, A R; McElhinney, L M; Brookes, S M; Johnson, N; Keene, V; Parsons, G; Soldan, A

    2002-04-06

    The Pet Travel Scheme (PETS) commenced on February 28, 2000, allowing pet dogs and cats from named countries to enter the UK without spending six months in quarantine as long as they met specific criteria. Since the start of the scheme to the end of February 2002, more than 45,000 animals have successfully entered the UK under PETS. In this article, Dr Tony Fooks and colleagues consider the results of serological testing under the scheme at the Veterinary Laboratories Agency and look to future developments.

  14. Performance of hashed cache data migration schemes on multicomputers

    NASA Technical Reports Server (NTRS)

    Hiranandani, Seema; Saltz, Joel; Mehrotra, Piyush; Berryman, Harry

    1991-01-01

    After conducting an examination of several data-migration mechanisms which permit an explicit and controlled mapping of data to memory, a set of schemes for storage and retrieval of off-processor array elements is experimentally evaluated and modeled. All schemes considered have their basis in the use of hash tables for efficient access of nonlocal data. The techniques in question are those of hashed cache, partial enumeration, and full enumeration; in these, nonlocal data are stored in hash tables, so that the operative difference lies in the amount of memory used by each scheme and in the retrieval mechanism used for nonlocal data.

  15. Triangle based TVD schemes for hyperbolic conservation laws

    NASA Technical Reports Server (NTRS)

    Durlofsky, Louis J.; Osher, Stanley; Engquist, Bjorn

    1990-01-01

    A triangle based total variation diminishing (TVD) scheme for the numerical approximation of hyperbolic conservation laws in two space dimensions is constructed. The novelty of the scheme lies in the nature of the preprocessing of the cell averaged data, which is accomplished via a nearest neighbor linear interpolation followed by a slope limiting procedures. Two such limiting procedures are suggested. The resulting method is considerably more simple than other triangle based non-oscillatory approximations which, like this scheme, approximate the flux up to second order accuracy. Numerical results for linear advection and Burgers' equation are presented.

  16. An optimized quantum information splitting scheme with multiple controllers

    NASA Astrophysics Data System (ADS)

    Jiang, Min

    2016-12-01

    We propose an efficient scheme for splitting multi-qudit information with cooperative control of multiple agents. Each controller is assigned one controlling qudit, and he can monitor the state sharing of all multi-qudit information. Compared with the existing schemes, our scheme requires less resource consumption and approaches higher communication efficiency. In addition, our proposal involves only generalized Bell-state measurement, single-qudit measurement, one-qudit gates and a unitary-reduction operation, which makes it flexible and achievable for physical implementation.

  17. Implicit schemes and parallel computing in unstructured grid CFD

    NASA Technical Reports Server (NTRS)

    Venkatakrishnam, V.

    1995-01-01

    The development of implicit schemes for obtaining steady state solutions to the Euler and Navier-Stokes equations on unstructured grids is outlined. Applications are presented that compare the convergence characteristics of various implicit methods. Next, the development of explicit and implicit schemes to compute unsteady flows on unstructured grids is discussed. Next, the issues involved in parallelizing finite volume schemes on unstructured meshes in an MIMD (multiple instruction/multiple data stream) fashion are outlined. Techniques for partitioning unstructured grids among processors and for extracting parallelism in explicit and implicit solvers are discussed. Finally, some dynamic load balancing ideas, which are useful in adaptive transient computations, are presented.

  18. HDG schemes for stationary convection-diffusion problems

    NASA Astrophysics Data System (ADS)

    Dautov, R. Z.; Fedotov, E. M.

    2016-11-01

    For stationary linear convection-diffusion problems, we construct and study a hybridized scheme of the discontinuous Galerkin method on the basis of an extended mixed statement of the problem. Discrete schemes can be used for the solution of equations degenerating in the leading part and are stated via approximations to the solution of the problem, its gradient, the flow, and the restriction of the solution to the boundaries of elements. For the spaces of finite elements, we represent minimal conditions responsible for the solvability, stability and accuracy of the schemes.

  19. Quantum Ramp Secret Sharing Scheme and Quantum Operations

    NASA Astrophysics Data System (ADS)

    Xiao, Heling; Wang, Huifeng; Wang, Bin

    2016-09-01

    In order to improve the efficiency of quantum secret sharing, quantum ramp secret sharing schemes were proposed (Ogawa et al., Phys. Rev. A 72, 032318 [2005]), which had a trade-off between security and coding efficiency. In quantum ramp secret sharing, partial information about the secret is allowed to leak to a set of participants, called an intermediate set, which cannot fully reconstruct the secret. This paper revisits the size of a share in the quantum ramp secret scheme based on a relation between the quantum operations and the coherent information. We also propose an optimal quantum ramp secret sharing scheme.

  20. Pulse-Modulation Scheme For Voice And Telemetry

    NASA Technical Reports Server (NTRS)

    Mills, William J.

    1993-01-01

    Pulse-modulation scheme provides for transmission of 1 channel of voice information along with 16 channels of serially multiplexed analog iotelemetric information, all on single radio-frequency carrier signal. Encoder/multiplexer combination effects PMD scheme, in which biotelemetry encoded in time-division multiplex PIM, while voice encoded in PWM. Combination of PIM and PWM encoding called "pulse modulated data" or PMD. Principal advantage of scheme simplicity: comodulation of voice along with biotelemetry involves minimal additional circuitry in transmitter. In receiver, biotelemetric data extracted by ordinary PIM-encoding circuitry, not affected by voice PWM; and simple PWM decoder added to receiver to recover voice.