Science.gov

Sample records for masterless charge-control scheme

  1. Modular Battery Charge Controller

    NASA Technical Reports Server (NTRS)

    Button, Robert; Gonzalez, Marcelo

    2009-01-01

    A new approach to masterless, distributed, digital-charge control for batteries requiring charge control has been developed and implemented. This approach is required in battery chemistries that need cell-level charge control for safety and is characterized by the use of one controller per cell, resulting in redundant sensors for critical components, such as voltage, temperature, and current. The charge controllers in a given battery interact in a masterless fashion for the purpose of cell balancing, charge control, and state-of-charge estimation. This makes the battery system invariably fault-tolerant. The solution to the single-fault failure, due to the use of a single charge controller (CC), was solved by implementing one CC per cell and linking them via an isolated communication bus [e.g., controller area network (CAN)] in a masterless fashion so that the failure of one or more CCs will not impact the remaining functional CCs. Each micro-controller-based CC digitizes the cell voltage (V(sub cell)), two cell temperatures, and the voltage across the switch (V); the latter variable is used in conjunction with V(sub cell) to estimate the bypass current for a given bypass resistor. Furthermore, CC1 digitizes the battery current (I1) and battery voltage (V(sub batt) and CC5 digitizes a second battery current (I2). As a result, redundant readings are taken for temperature, battery current, and battery voltage through the summation of the individual cell voltages given that each CC knows the voltage of the other cells. For the purpose of cell balancing, each CC periodically and independently transmits its cell voltage and stores the received cell voltage of the other cells in an array. The position in the array depends on the identifier (ID) of the transmitting CC. After eight cell voltage receptions, the array is checked to see if one or more cells did not transmit. If one or more transmissions are missing, the missing cell(s) is (are) eliminated from cell

  2. Lithium-Ion Cell Charge Control Unit

    NASA Technical Reports Server (NTRS)

    Reid, Concha; Button, Robert; Manzo, Michelle; McKissock, Barbara; Miller, Thomas; Gemeiner, Russel; Bennett, William; Hand, Evan

    2006-01-01

    Life-test data of Lithium-Ion battery cells is critical in order to establish their performance capabilities for NASA missions and Exploration goals. Lithium-ion cells have the potential to replace rechargeable alkaline cells in aerospace applications, but they require a more complex charging scheme than is typically required for alkaline cells. To address these requirements in our Lithium-Ion Cell Test Verification Program, a Lithium-Ion Cell Charge Control Unit was developed by NASA Glenn Research Center (GRC). This unit gives researchers the ability to test cells together as a pack, while allowing each cell to charge individually. This allows the inherent cell-to-cell variations to be addressed on a series string of cells and results in a substantial reduction in test costs as compared to individual cell testing. The Naval Surface Warfare Center at Crane, Indiana developed a power reduction scheme that works in conjunction with the Lithium-Ion Cell Charge Control Unit. This scheme minimizes the power dissipation required by the circuitry to prolong circuit life and improve its reliability.

  3. Lithium-Ion Cell Charge-Control Unit Developed

    NASA Technical Reports Server (NTRS)

    Reid, Concha M.; Manzo, Michelle A.; Buton, Robert M.; Gemeiner, Russel

    2005-01-01

    A lithium-ion (Li-ion) cell charge-control unit was developed as part of a Li-ion cell verification program. This unit manages the complex charging scheme that is required when Li-ion cells are charged in series. It enables researchers to test cells together as a pack, while allowing each cell to charge individually. This allows the inherent cell-to-cell variations to be addressed on a series string of cells and reduces test costs substantially in comparison to individual cell testing.

  4. Lithium Ion Source for Satellite Charge Control

    DTIC Science & Technology

    1990-06-01

    ePH^TOELE 1a b |, SOLAR PHOTONS PH3TOL ETROtJS ATTRACTED BACK BY THE SURFACE CHARGE Figure 1. Qualitative illustration of the charging : of a surface by...LITHIUM ION SOURCE FOR SATELLITE CHARGE CONTROL 12 Personal Author(s) Song. Tae Ik 13a Type of Report 13b Time Covered Id Date of Report (year, month...if ncvessary and Identify by block number) Field Group Subgroup Lithium Ion Source, Satellite Charge Control 19 Abstract (continue on reverse if

  5. Charge-Control Unit for Testing Lithium-Ion Cells

    NASA Technical Reports Server (NTRS)

    Reid, Concha M.; Mazo, Michelle A.; Button, Robert M.

    2008-01-01

    A charge-control unit was developed as part of a program to validate Li-ion cells packaged together in batteries for aerospace use. The lithium-ion cell charge-control unit will be useful to anyone who performs testing of battery cells for aerospace and non-aerospace uses and to anyone who manufacturers battery test equipment. This technology reduces the quantity of costly power supplies and independent channels that are needed for test programs in which multiple cells are tested. Battery test equipment manufacturers can integrate the technology into their battery test equipment as a method to manage charging of multiple cells in series. The unit manages a complex scheme that is required for charging Li-ion cells electrically connected in series. The unit makes it possible to evaluate cells together as a pack using a single primary test channel, while also making it possible to charge each cell individually. Hence, inherent cell-to-cell variations in a series string of cells can be addressed, and yet the cost of testing is reduced substantially below the cost of testing each cell as a separate entity. The unit consists of electronic circuits and thermal-management devices housed in a common package. It also includes isolated annunciators to signal when the cells are being actively bypassed. These annunciators can be used by external charge managers or can be connected in series to signal that all cells have reached maximum charge. The charge-control circuitry for each cell amounts to regulator circuitry and is powered by that cell, eliminating the need for an external power source or controller. A 110-VAC source of electricity is required to power the thermal-management portion of the unit. A small direct-current source can be used to supply power for an annunciator signal, if desired.

  6. Battery charge control: Which approach is best?

    NASA Technical Reports Server (NTRS)

    Lurie, Charles

    1994-01-01

    The question of the best approach for battery charge control is addressed from two points of view: from the battery point-of-view; and from the spacecraft/mission point-of-view. In terms of performance, more aggressive charging can result in higher discharge voltage and capacity; however, aggressive charging usually implies more overcharge at higher rates and a concomitant higher end of charge temperature (higher stress, shorter life). In terms of life, benign charging can result in lower discharge voltage and capacity (poorer performance). Additionally, benign, or low stress charging, usually implies less overcharge at lower rates with lower end of charge temperature (lower stress, longer life). A discussion of these topics is presented in viewgraph form.

  7. Performance of battery charge controllers: First year test report

    SciTech Connect

    Dunlop, J. ); Bower, W. ); Harrington, S. )

    1991-01-01

    The results of the first year of an evaluation of charge controllers for stand-alone photovoltaic (PV) systems are presented. The objectives of the test program are to positively influence the development of battery charge controllers for stand-alone PV applications and to develop design and application criteria that will improve PV system reliability and battery performance. Future goals are to expand the evaluation program to include various battery technologies and controller algorithms. Also, the information is being communicated to manufacturers to aid in the design of more effective and reliable charge controllers for PV systems. Eight different models of small (nominal 10 amp) charge controllers are being subjected to a comprehensive evaluation. These evaluations include operational tests in identical stand-alone PV systems and environmental and electrical cycling tests. Selected custom tests are also performed on the controllers to determine the response to transients, installation requirements and system design compatibilities. Data presented in this paper include measured electrical characteristics of the controllers, temperature effects on set points, and operational performance in PV systems both in the lab and in the field. A comparison is presented for four different charge controller algorithms which include array-shunt, series-interrupting, series-linear constant-voltage and series-linear-multistep constant-current. 9 refs., 11 figs., 2 tabs.

  8. Electrical charging control apparatus and method, and solar to electrical energy conversion apparatus incorporating such charging control apparatus

    SciTech Connect

    Staler, T.; Yerkes, J.W.

    1984-06-05

    Electrical charging control apparatus regulates the charging of a rechargeable battery by a solar panel. The control of the charging is through a relay which when closed directly connects the output and charging terminal of the solar panel to the output and charging terminal of the battery to permit the charging of the battery by the solar panel. Such coupling is in turn under the terminals are in a coupling prevention relationship chosen to prevent significant discharging of the battery through the solar panel; of breaker apparatus which breaks a coupling after a predetermined period of time; and of additional signal-tester apparatus which causes a termination of the coupling when the signal at the connected terminals reaches a chosen charging termination threshold. The breaking of the coupling, which can result in a periodic breaking, permits the testing for discharging prevention. A charging control method is in accordance with the above outlined method of operation of the charging control apparatus.

  9. Optimal charge control strategies for stationary photovoltaic battery systems

    NASA Astrophysics Data System (ADS)

    Li, Jiahao; Danzer, Michael A.

    2014-07-01

    Battery systems coupled to photovoltaic (PV) modules for example fulfill one major function: they locally decouple PV generation and consumption of electrical power leading to two major effects. First, they reduce the grid load, especially at peak times and therewith reduce the necessity of a network expansion. And second, they increase the self-consumption in households and therewith help to reduce energy expenses. For the management of PV batteries charge control strategies need to be developed to reach the goals of both the distribution system operators and the local power producer. In this work optimal control strategies regarding various optimization goals are developed on the basis of the predicted household loads and PV generation profiles using the method of dynamic programming. The resulting charge curves are compared and essential differences discussed. Finally, a multi-objective optimization shows that charge control strategies can be derived that take all optimization goals into account.

  10. Non-uniform space charge controlled KTN beam deflector

    NASA Astrophysics Data System (ADS)

    Chao, Ju-Hung; Zhu, Wenbin; Chen, Chang-Jiang; Yin, Stuart; Hoffman, Robert C.

    2016-09-01

    A non-uniform space charge-controlled KTN beam deflector is presented and analyzed. We found that a non-uniform space charge can result in a non-uniform beam deflection angles. This effect can be useful for some applications such as electric field controlled beam separation. However, a non-uniform space charge needs to be avoided if one wants uniform beam deflection throughout the entire crystal.

  11. Battery charge control with temperature compensated voltage limit

    NASA Technical Reports Server (NTRS)

    Thierfelder, H. E.

    1983-01-01

    Battery charge control for orbiting spacecraft with mission durations from three to ten years, is a critical design feature that is discussed. Starting in 1974, the General Electric Space Systems Division designed, manufactured and tested battery systems for six different space programs. Three of these are geosynchronous missions, two are medium altitude missions and one is a near-earth mission. All six power subsystems contain nickel cadmium batteries which are charged using a temperature compensated voltage limit. This charging method was found to be successful in extending the life of nickel cadmium batteries in all three types of earth orbits. Test data and flight data are presented for each type of orbit.

  12. Aircraft battery state of charge and charge control system

    NASA Astrophysics Data System (ADS)

    Viswanathan, S.; Charkey, A.

    1986-02-01

    This Interim Report describes work done in developing an aircraft battery state of charge and charge control system. The basis for this system developed by ERC is a nickel-oxygen (NiO2) Pilot cell (0.374 Ah). This pilot cell is cycled in tandem with a nickel-cadmium battery. The oxygen pressure of the pilot cell is utilized to determine and control the state of charge of the nickel-cadmium battery. The NiO2 pilot cell baseline performance was determined during this period. The effect of using different nickel electrodes (ERC, SAFT, MARATHON) was also performed.

  13. UV-LED-based charge control for LISA

    NASA Astrophysics Data System (ADS)

    Olatunde, Taiwo; Shelley, Ryan; Chilton, Andrew; Ciani, Giacomo; Mueller, Guido; Conklin, John

    2014-03-01

    The test masses inside the LISA gravitational reference sensors (GRS) must maintain almost pure geodesic motion for gravitational waves to be successfully detected. The residual accelerations have to stay below 3fm/s2/rtHz at all frequencies between 0.1 and 3 mHz. One of the well known noise sources is associated with the charges on the test masses which couple to stray electrical potentials and external electro-magnetic fields. The LISA pathfinder (LPF) will use Hg-discharge lamps emitting mostly around 253 nm to discharge the test masses via photoemission in its 2015/16 flight. A future LISA mission launched around 2030 will likely replace the lamps with newer UV-LEDs. UV-LEDs have a lower mass, a better power efficiency, and are smaller than their Hg counterparts. Furthermore, the latest generation produces light at 240 nm, with energy well above the work function of pure gold. I will describe a preliminary design for effective charge control through photoelectric effect by using these LEDs. The effectiveness of this method is verified by taking Quantum Efficiency (QE) measurements which relate the number of electrons emitted to the number of photons incident on the Au test mass surface. This presentation addresses our initial results and future plans which includes implementation and testing in the UF torsion pendulum and space-qualification in a small satellite mission which will launch in the summer of 2014, through a collaboration with Stanford, KACST, and NASA Ames Research Center.

  14. 240 nm UV LEDs for LISA test mass charge control

    NASA Astrophysics Data System (ADS)

    Olatunde, Taiwo; Shelley, Ryan; Chilton, Andrew; Serra, Paul; Ciani, Giacomo; Mueller, Guido; Conklin, John

    2015-05-01

    Test Masses inside the LISA Gravitational Reference Sensor must maintain almost pure geodesic motion for gravitational waves to be successfully detected. LISA requires residual test mass accelerations below 3 fm/s2/√Hz at all frequencies between 0.1 and 3 mHz. One of the well-known noise sources is associated with the charges on the test masses which couple to stray electrical potentials and external electromagnetic fields. LISA Pathfinder will use Hg-discharge lamps emitting mostly around 254 nm to discharge the test masses via photoemission in its 2015/16 flight. A future LISA mission launched around 2030 will likely replace the lamps with newer UV-LEDs. Presented here is a preliminary study of the effectiveness of charge control using latest generation UV-LEDs which produce light at 240 nm with energy above the work function of pure Au. Their lower mass, better power efficiency and small size make them an ideal replacement for Hg lamps.

  15. Masterless Distributed Computing Over Mobile Devices

    DTIC Science & Technology

    2012-09-01

    particular, Dalvik was designed to work with limited processor speed, limited RAM , no swap space, and low power consumption. Every Android ...devices that have limited processor speed and limited RAM . The developers of Android decided that the user interface (UI) was the most important...Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project

  16. The effect of switched array battery charge control on CRRES spacecraft: 3 + month data summary

    NASA Technical Reports Server (NTRS)

    Olbert, Phil

    1991-01-01

    The following topics are covered in viewgraph format: Combined Release and Radiation Effects Satellite (CRRES) orbit parameters; battery charge control; battery description; battery current and voltage output during one orbit; and battery reconditioning discharge profile.

  17. PV batteries and charge controllers: Technical issues, costs, and market trends

    SciTech Connect

    Hammond, R.L.; Turpin, J.F.; Corey, G.P.; Hund, T.D.; Harrington, S.R.

    1997-11-01

    A survey of US system integrators, charge controller manufacturers, and battery manufacturers was conducted in 1996 to determine market and application trends. This survey was sponsored by the USDOE. Results from 21 system integrators show a 1995 PV battery sales of $4.76 million. Using the survey results, a top down market analysis was conducted with a total predicted US battery market of $34.7 million and a world wide market of US $302 million. The survey also indicated that 71% (of dollars) were spent on VRLA and 29% on flooded lead-acid batteries. Eighty percent of charge controllers were ON-OFF, vs. PWM or constant voltage.

  18. Battery charging control methods, electric vehicle charging methods, battery charging apparatuses and rechargeable battery systems

    DOEpatents

    Tuffner, Francis K [Richland, WA; Kintner-Meyer, Michael C. W. [Richland, WA; Hammerstrom, Donald J [West Richland, WA; Pratt, Richard M [Richland, WA

    2012-05-22

    Battery charging control methods, electric vehicle charging methods, battery charging apparatuses and rechargeable battery systems. According to one aspect, a battery charging control method includes accessing information regarding a presence of at least one of a surplus and a deficiency of electrical energy upon an electrical power distribution system at a plurality of different moments in time, and using the information, controlling an adjustment of an amount of the electrical energy provided from the electrical power distribution system to a rechargeable battery to charge the rechargeable battery.

  19. Spacecraft charging control by thermal, field emission with lanthanum-hexaboride emitters

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1978-01-01

    Thermal, field emitters of lanthanum (or perhaps cerium) hexaboride (LaB6) with temperature variability up to about 1500K are suggested for spacecraft charging control. Such emitters operate at much lower voltages with considerably more control and add plasma-diagnostic versatility. These gains should outweigh the additional complexity of providing heat for the LaB6 thermal, field emitter.

  20. Battery and charge controller evaluations in small stand-alone PV systems

    NASA Astrophysics Data System (ADS)

    Woodworth, J. R.; Thomas, M. G.; Stevens, J. W.; Dunlop, J. L.; Swamy, M. R.; Demetrius, L.; Harrington, S. R.

    1994-12-01

    We report the results of two separate long-term tests of batteries and charge controllers in small stand-alone PV systems. In these experiments, seven complete systems were tested for two years at each of two locations: Sandia National Laboratories in Albuquerque and the Florida Solar Energy Center in Cape Canaveral, Florida. Each system contained a PV array, flooded-lead-acid battery, a charge controller and a resistive load. Performance of the systems was strongly influenced by the difference in solar irradiance at the two sites, with some batteries at Sandia exceeding manufacturer's predictions for cycle life. System performance was strongly correlated with regulation reconnect voltage (R(sup 2) correlation coefficient = 0.95) but only weakly correlated with regulation voltage. We will also discuss details of system performance, battery lifetime and battery water consumption.

  1. Battery and charge controller evaluations in small stand-alone PV systems

    SciTech Connect

    Woodworth, J.R.; Thomas, M.G.; Stevens, J.W.; Dunlop, J.L.; Swamy, M.R.; Demetrius, L.; Harrington, S.R.

    1994-07-01

    We report the results of to separate long-term tests of batteries and charge controllers in small stand-alone PV systems. In these experiments, seven complete systems were tested for two years at each of two locations: Sandia National Laboratories in Albuquerque and the Florida Solar Energy Center in Cape Canaveral, Florida. Each system contained a PV array, flooded-lead-acid battery, a charge controller and a resistive load. Performance of the systems was strongly influenced by the difference in solar irradiance at the two sites, with some batteries at Sandia exceeding manufacturer`s predictions for cycle life. System performance was strongly correlated with regulation reconnect voltage (R{sup 2} correlation coefficient = 0.95) but only weakly correlated with regulation voltage. We will also discuss details of system performance, battery lifetime and battery water consumption.

  2. Photovoltaic battery & charge controller market & applications survey. An evaluation of the photovoltaic system market for 1995

    SciTech Connect

    Hammond, R.L.; Turpin, J.F.; Corey, G.P.

    1996-12-01

    Under the sponsorship of the Department of Energy, Office of Utility Technologies, the Battery Analysis and Evaluation Department and the Photovoltaic System Assistance Center of Sandia National Laboratories (SNL) initiated a U.S. industry-wide PV Energy Storage System Survey. Arizona State University (ASU) was contracted by SNL in June 1995 to conduct the survey. The survey included three separate segments tailored to: (a) PV system integrators, (b) battery manufacturers, and (c) PV charge controller manufacturers. The overall purpose of the survey was to: (a) quantify the market for batteries shipped with (or for) PV systems in 1995, (b) quantify the PV market segments by battery type and application for PV batteries, (c) characterize and quantify the charge controllers used in PV systems, (d) characterize the operating environment for energy storage components in PV systems, and (e) estimate the PV battery market for the year 2000. All three segments of the survey were mailed in January 1996. This report discusses the purpose, methodology, results, and conclusions of the survey.

  3. Evaluation of the batteries and charge controllers in small stand-alone photovoltaic systems

    SciTech Connect

    Woodworth, J.R.; Thomas, M.G.; Stevens, J.W.; Harrington, S.R.; Dunlop, J.P.; Swamy, M.R.; Demetrius, L.

    1994-12-31

    In this paper, the authors report the results of long-term tests on 14 separate small stand-alone PV systems. These tests were carried out at two separate laboratories in Albuquerque, New Mexico and in Cape Canaveral, Florida. The systems were heavily instrumented to help determine what effects voltage regulation set points have on system water loss, battery capacity lifetime and system reliability. The authors find that under the proper conditions, the flooded lead-acid batteries in these PV systems can achieve cycle-lifetimes comparable to manufacturer`s expectations for conventional battery applications. They also find that both the overcharge and overdischarge protection provided by the system charge controllers were necessary for proper operation of these systems. Details of the data and a number of conclusions for system designers are presented.

  4. A pulse-width modulated, high reliability charge controller for small photovoltaic systems

    SciTech Connect

    Gerken, K.; Welsh, D.

    1997-02-01

    This report presents the results of a development effort to design, test and begin production of a new class of small photovoltaic (PV) charge controllers. Sandia National Laboratories provided technical support, test data and financial support through a Balance-of-System Development contract. One of the objectives of the development was to increase user confidence in small PV systems by improving the reliability and operating life of the system controllers. Another equally important objective was to improve the economics of small PV systems by extending the battery lifetimes. Using new technology and advanced manufacturing techniques, these objectives were accomplished. Because small stand-alone PV systems account for over one third of all PV modules shipped, the positive impact of improving the reliability and economics of PV systems in this market segment will be felt throughout the industry. The results of verification testing of the new product are also included in this report. The initial design goals and specifications were very aggressive, but the extensive testing demonstrates that all the goals were achieved. Production of the product started in May at a rate of 2,000 units per month. Over 40 Morningstar distributors (5 US and 35 overseas) have taken delivery in the first 2 months of shipments. Initial customer reactions to the new controller have been very favorable.

  5. Identification procedures for the charge-controlled nonlinear noise model of microwave electron devices

    NASA Astrophysics Data System (ADS)

    Filicori, Fabio; Traverso, Pier Andrea; Florian, Corrado; Borgarino, Mattia

    2004-05-01

    The basic features of the recently proposed Charge-Controlled Non-linear Noise (CCNN) model for the prediction of low-to-high-frequency noise up-conversion in electron devices under large-signal RF operation are synthetically presented. It is shown that the different noise generation phenomena within the device can be described by four equivalent noise sources, which are connected at the ports of a "noiseless" device model and are non-linearly controlled by the time-varying instantaneous values of the intrinsic device voltages. For the empirical identification of the voltage-controlled equivalent noise sources, different possible characterization procedures, based not only on conventional low-frequency noise data, but also on different types of noise measurements carried out under large-signal RF operating conditions are discussed. As an example of application, the measurement-based identification of the CCNN model for a GaInP heterojunction bipolar microwave transistor is presented. Preliminary validation results show that the proposed model can describe with adequate accuracy not only the low-frequency noise of the HBT, but also its phase-noise performance in a prototype VCO implemented by using the same monolithic GaAs technology.

  6. Chargeability measurements of selected pharmaceutical dry powders to assess their electrostatic charge control capabilities.

    PubMed

    Ramirez-Dorronsoro, Juan-Carlos; Jacko, Robert B; Kildsig, Dane O

    2006-01-01

    The purpose of this study was to develop an instrument (the Purdue instrument) and the corresponding methodologies to measure the electrostatic charge development (chargeability) of dry powders when they are in dynamic contact with stainless steel surfaces. The system used an inductive noncontact sensor located inside an aluminum Faraday cage and was optimized to measure the charging capabilities of a fixed volume of powder (0.5 cc). The chargeability of 5,5-diphenyl-hydantoin, calcium sulfate dihydrate, cimetidine, 3 grades of colloidal silicon dioxide, magnesium stearate, 4 grades of microcrystalline cellulose, salicylic acid, sodium carbonate, sodium salicylate, spray-dried lactose, and sulfinpyrazone were tested at 4 linear velocities, and the particle size distribution effect was assessed for 3 different grades of colloidal silicon dioxide and 4 different grades of microcrystalline cellulose. The chargeability values exhibited a linear relationship for the range of velocities studied, with colloidal silicon dioxide exhibiting the maximum negative chargeability and with spray-dried lactose being the only compound to exhibit positive chargeability. The instrument sensitivity was improved by a factor of 2 over the first generation version, and the electrostatic charge measurements were reproducible with relative standard deviations ranging from nondetectable to 33.7% (minimum of 3 replicates). These results demonstrate the feasibility of using the Purdue instrument to measure the electrostatic charge control capabilities of pharmaceutical dry powders with a reasonable level of precision.

  7. The Master-Less Studio: An Autonomous Education Community

    ERIC Educational Resources Information Center

    Lebler, Don

    2006-01-01

    In recent times, it has become difficult for even the best conservatorium graduates to achieve the traditional goals of concert performance or secure orchestral positions and this has profound effects on the work practices of musicians. There are important implications for teaching in a conservatorium, in terms of providing a learning experience…

  8. Space-charge-controlled field emission model of current conduction through Al2O3 films

    NASA Astrophysics Data System (ADS)

    Hiraiwa, Atsushi; Matsumura, Daisuke; Kawarada, Hiroshi

    2016-02-01

    This study proposes a model for current conduction in metal-insulator-semiconductor (MIS) capacitors, assuming the presence of two sheets of charge in the insulator, and derives analytical formulae of field emission (FE) currents under both negative and positive bias. Since it is affected by the space charge in the insulator, this particular FE differs from the conventional FE and is accordingly named the space-charge-controlled (SCC) FE. The gate insulator of this study was a stack of atomic-layer-deposition Al2O3 and underlying chemical SiO2 formed on Si substrates. The current-voltage (I-V) characteristics simulated using the SCC-FE formulae quantitatively reproduced the experimental results obtained by measuring Au- and Al-gated Al2O3/SiO2 MIS capacitors under both biases. The two sheets of charge in the Al2O3 films were estimated to be positive and located at a depth of greater than 4 nm from the Al2O3/SiO2 interface and less than 2 nm from the gate. The density of the former is approximately 1 × 1013 cm-2 in units of electronic charge, regardless of the type of capacitor. The latter forms a sheet of dipoles together with image charges in the gate and hence causes potential jumps of 0.4 V and 1.1 V in the Au- and Al-gated capacitors, respectively. Within a margin of error, this sheet of dipoles is ideally located at the gate/Al2O3 interface and effectively reduces the work function of the gate by the magnitude of the potential jumps mentioned above. These facts indicate that the currents in the Al2O3/SiO2 MIS capacitors are enhanced as compared to those in ideal capacitors and that the currents in the Al-gated capacitors under negative bias (electron emission from the gate) are more markedly enhanced than those in the Au-gated capacitors. The larger number of gate-side dipoles in the Al-gated capacitors is possibly caused by the reaction between the Al and Al2O3, and therefore gate materials that do not react with underlying gate insulators should be chosen

  9. Performance of Li-Ion Cells Under Battery Voltage Charge Control

    NASA Technical Reports Server (NTRS)

    Rao, Gopalakrishna M.; Vaidyanathan, Hari; Day, John H. (Technical Monitor)

    2001-01-01

    A study consisting of electrochemical characterization and Low-Earth-Orbit (LEO) cycling of Li-Ion cells from three vendors was initiated in 1999 to determine the cycling performance and to infuse the new technology in the future NASA missions. The 8-cell batteries included in this evaluation are prismatic cells manufactured by Mine Safety Appliances Company (MSA), cylindrical cells manufactured by SAFT and prismatic cells manufactured by Yardney Technical Products, Inc. (YTP). The three batteries were cycle tested in the LEO regime at 40% depth of discharge, and under a charge control technique that consists of battery voltage clamp with a current taper. The initial testing was conducted at 20 C; however, the batteries were cycled also intermittently at low temperatures. YTP 20 Ah cells consisted of mixed-oxide (Co and Ni) positive, graphitic carbon negative, LIPF6 salt mixed with organic carbonate solvents. The battery voltage clamp was 32 V. The low temperature cycling tests started after 4575 cycles at 20 C. The cells were not capable of cycling. at low temperature since the charge acceptance at battery level was poor. There was a cell in the battery that showed too high an end-of-charge (EOC) voltage thereby limiting the ability to charge the rest of the cells in the battery. The battery has completed 6714 cycles. SAFT 12 Ah cells consisted of mixed-oxide (Co and NO positive, graphitic carbon negative, LiPF6 salt mixed with organic carbonate solvents. The battery voltage clamp was for 30.8 V. The low temperature cycling tests started after 4594 cycles at 20 C. A cell that showed low end of discharge (EOD) and EOC voltages and three other cells that showed higher EOC voltages limited the charge acceptance at the selected voltage limit during charge. The cells were capable of cycling at 10 C and 0 C but the charge voltage limit had to be increased to 34.3 V (4.3 V per cell). The low temperature cycling may have induced poor chargeability since the voltage had to

  10. UV LED charge control of an electrically isolated proof mass in a Gravitational Reference Sensor configuration at 255 nm

    NASA Astrophysics Data System (ADS)

    Balakrishnan, Karthik; Sun, Ke-Xun

    2012-07-01

    Precise control over the potential of an electrically isolated proof mass is necessary for the operation of devices such as a Gravitational Reference Sensor (GRS) and satellite missions such as LISA. We show that AlGaN UV LEDs operating at 255 nm are an effective substitute for Mercury vapor lamps used in previous missions because of their ability to withstand space qualification levels of vibration and thermal cycling. After 27 thermal and thermal vacuum cycles and 9 minutes of 14.07 g RMS vibration, there is less than 3% change in current draw, less than 15% change in optical power, and no change in spectral peak or FWHM (full width at half maximum). We also demonstrate UV LED stimulated photoemission from a wide variety of thin film carbide proof mass coating candidates (SiC, Mo2C, TaC, TiC, ZrC) that were applied using electron beam evaporation on an Aluminum 6061-T6 substrate. All tested carbide films have measured quantum efficiencies of 3.8-6.8*10^-7 and reflectivities of 0.11-0.15, which compare favorably with the properties of previously used gold films. We demonstrate the ability to control proof mass potential on an 89 mm diameter spherical proof mass over a 20 mm gap in a GRS-like configuration. Proof mass potential was measured via a non-contact DC probe, which would allow control without introducing dynamic forcing of the spacecraft. Finally we provide a look ahead to an upcoming technology demonstration mission of UV LEDs and future applications toward charge control of electrically isolated proof masses.

  11. Twin Signature Schemes, Revisited

    NASA Astrophysics Data System (ADS)

    Schäge, Sven

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

  12. 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.

  13. 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.

  14. 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.

  15. 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)

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Satellite Spacecraft Charging Control Materials.

    DTIC Science & Technology

    1980-04-01

    OF TH4IS PAGE(Iflun Data AnfoeE) Block 20: The charge dissipation mechanisms for silica fabrics in a geo9ynchronous magnetic substorm environment...or on orbit, these grounding techni- ques fail, open electrically, as a result of vibration, corrosion, electrical or mechanical /thermal effects...aluminized FEP with outstanding, mechanical , optical and electrical properties (3) . These various materials have been tested in the past under

  3. Three order increase in scanning speed of space charge-controlled KTN deflector by eliminating electric field induced phase transition in nanodisordered KTN

    PubMed Central

    Zhu, Wenbin; Chao, Ju-Hung; Chen, Chang-Jiang; Yin, Shizhuo; Hoffman, Robert C.

    2016-01-01

    In this paper, we report a three orders-of-magnitude increase in the speed of a space-charge-controlled KTN beam deflector achieved by eliminating the electric field-induced phase transition (EFIPT) in a nanodisordered KTN crystal. Previously, to maximize the electro-optic effect, a KTN beam deflector was operated at a temperature slightly above the Curie temperature. The electric field could cause the KTN to undergo a phase transition from the paraelectric phase to the ferroelectric phase at this temperature, which causes the deflector to operate in the linear electro-optic regime. Since the deflection angle of the deflector is proportional to the space charge distribution but not the magnitude of the applied electric field, the scanning speed of the beam deflector is limited by the electron mobility within the KTN crystal. To overcome this speed limitation caused by the EFIPT, we propose to operate the deflector at a temperature above the critical end point. This results in a significant increase in the scanning speed from the microsecond to nanosecond regime, which represents a major technological advance in the field of fast speed beam scanners. This can be highly beneficial for many applications including high-speed imaging, broadband optical communications, and ultrafast laser display and printing. PMID:27610923

  4. Three order increase in scanning speed of space charge-controlled KTN deflector by eliminating electric field induced phase transition in nanodisordered KTN.

    PubMed

    Zhu, Wenbin; Chao, Ju-Hung; Chen, Chang-Jiang; Yin, Shizhuo; Hoffman, Robert C

    2016-09-09

    In this paper, we report a three orders-of-magnitude increase in the speed of a space-charge-controlled KTN beam deflector achieved by eliminating the electric field-induced phase transition (EFIPT) in a nanodisordered KTN crystal. Previously, to maximize the electro-optic effect, a KTN beam deflector was operated at a temperature slightly above the Curie temperature. The electric field could cause the KTN to undergo a phase transition from the paraelectric phase to the ferroelectric phase at this temperature, which causes the deflector to operate in the linear electro-optic regime. Since the deflection angle of the deflector is proportional to the space charge distribution but not the magnitude of the applied electric field, the scanning speed of the beam deflector is limited by the electron mobility within the KTN crystal. To overcome this speed limitation caused by the EFIPT, we propose to operate the deflector at a temperature above the critical end point. This results in a significant increase in the scanning speed from the microsecond to nanosecond regime, which represents a major technological advance in the field of fast speed beam scanners. This can be highly beneficial for many applications including high-speed imaging, broadband optical communications, and ultrafast laser display and printing.

  5. Highly efficient blue- and white-organic light-emitting diode based on dual recombination zones with a charge control layer.

    PubMed

    Lee, Seok Jae; Koo, Ja Ryong; Shin, Hyun Su; Kim, Bo Young; Park, Hye Rim; Kim, Young Kwan; Ha, Yunkyoung

    2012-07-01

    Highly efficient blue phosphorescent organic light-emitting diodes are investigated using iridium(Ill) bis[(4,6-di-fluorophenyl)-pyridinato-N,C2']picolinate doped in N,N'-dicarbazolyl-3,5-benzene (mCP) with a charge control layer (CCL) as the dual recombination zone (DRZ) system. DRZ with CCL was used to form a broad recombination zone and exciton confinement within each emission zone. Holes and electrons can be easily transported through the CCL, which were a mixed p-type mCP and n-type 2,2',2"-(1,3,5-benzenetryl) tris(1-phenyl)-1H-benzimidazol, for controlling the carrier movement. The CCL can play a role in triplet exciton blocking as expected from high triplet energy levels as well. Additionally, a white organic light-emitting diode was fabricated using a new phosphorescent orange emitter: bis[2-(2,4-difluorophenyl)pyridinato]iridium 2-(2-hydroxyphenyl)benzothia zolate doped in DRZ. The white device showed a maximum luminous efficiency of 23.15 cd/A, a maximum external quantum efficiency of 9.56%, and a maximum power efficiency of 13.37 lm/W. It also showed white emission with CIEx,y coordinates of (x = 0.33, y = 0.41) at 8 V.

  6. Three order increase in scanning speed of space charge-controlled KTN deflector by eliminating electric field induced phase transition in nanodisordered KTN

    NASA Astrophysics Data System (ADS)

    Zhu, Wenbin; Chao, Ju-Hung; Chen, Chang-Jiang; Yin, Shizhuo; Hoffman, Robert C.

    2016-09-01

    In this paper, we report a three orders-of-magnitude increase in the speed of a space-charge-controlled KTN beam deflector achieved by eliminating the electric field-induced phase transition (EFIPT) in a nanodisordered KTN crystal. Previously, to maximize the electro-optic effect, a KTN beam deflector was operated at a temperature slightly above the Curie temperature. The electric field could cause the KTN to undergo a phase transition from the paraelectric phase to the ferroelectric phase at this temperature, which causes the deflector to operate in the linear electro-optic regime. Since the deflection angle of the deflector is proportional to the space charge distribution but not the magnitude of the applied electric field, the scanning speed of the beam deflector is limited by the electron mobility within the KTN crystal. To overcome this speed limitation caused by the EFIPT, we propose to operate the deflector at a temperature above the critical end point. This results in a significant increase in the scanning speed from the microsecond to nanosecond regime, which represents a major technological advance in the field of fast speed beam scanners. This can be highly beneficial for many applications including high-speed imaging, broadband optical communications, and ultrafast laser display and printing.

  7. 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.

  8. 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.

  9. Relaxation schemes for Chebyshev spectral multigrid methods

    NASA Technical Reports Server (NTRS)

    Kang, Yimin; Fulton, Scott R.

    1993-01-01

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

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. [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.

  1. 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.

  2. Decoupling schemes for the SSC Collider

    SciTech Connect

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

    1993-05-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  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. 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.

  12. 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.

  13. 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

  14. 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.

  15. On Tenth Order Central Spatial Schemes

    SciTech Connect

    Sjogreen, B; Yee, H C

    2007-05-14

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

  16. 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.

  17. 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…

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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).

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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).

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Battery compatibility with photovoltaic charge controllers

    NASA Astrophysics Data System (ADS)

    Harrington, S. R.; Bower, W. I.

    Photovoltaic (PV) systems offer a cost-effective solution to provide electrical power for a wide variety of applications, with battery performance playing a major role in their success. Some of the results of an industry meeting regarding battery specifications and ratings that photovoltaic system designers require, but do not typically have available to them are presented. Communications between the PV industry and the battery industry regarding appropriate specifications were uncoordinated and poor in the past. The effort under way involving the PV industry and battery manufacturers is discussed and a working draft of specifications to develop and outline the information sorely needed on batteries is provided. The development of this information is referred to as 'Application Notes for Batteries in Photovoltaic Systems.' The content of these 'notes' was compiled from various sources, including the input from the results of a survey on battery use in the photovoltaic industry. Only lead-acid batteries are discussed.

  4. Automatic charge control system for satellites

    NASA Technical Reports Server (NTRS)

    Shuman, B. M.; Cohen, H. A.

    1985-01-01

    The SCATHA and the ATS-5 and 6 spacecraft provided insights to the problem of spacecraft charging at geosychronous altitudes. Reduction of the levels of both absolute and differential charging was indicated, by the emission of low energy neutral plasma. It is appropriate to complete the transition from experimental results to the development of a system that will sense the state-of-charge of a spacecraft, and, when a predetermined threshold is reached, will respond automatically to reduce it. A development program was initiated utilizing sensors comparable to the proton electrostatic analyzer, the surface potential monitor, and the transient pulse monitor that flew in SCATHA, and combine these outputs through a microprocessor controller to operate a rapid-start, low energy plasma source.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. Cooling scheme for turbine hot parts

    DOEpatents

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

    2000-01-01

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

  5. 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.

  6. 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.

  7. Upwind and symmetric shock-capturing schemes

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    1987-01-01

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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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…

  16. 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.

  17. 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.

  18. Creating Culturally Sustainable Agri-Environmental Schemes

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  19. Tunneling and the Emergent Universe Scheme

    NASA Astrophysics Data System (ADS)

    Labraña, Pedro

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

  20. [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.

  1. 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.

  2. 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.

  3. 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.

  4. 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).

  5. Configuration-Control Scheme Copes With Singularities

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun; Colbaugh, Richard D.

    1993-01-01

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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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).

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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…

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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 ⌉ .

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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%.

  6. 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.

  7. 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.

  8. 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%.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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).

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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

  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. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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…

  14. 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)

  15. 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.

  16. 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.

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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…

  9. 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.

  10. 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.

  11. 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....

  12. 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....

  13. 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....

  14. 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....

  15. 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....

  16. 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...

  17. 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…

  18. 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.

  19. 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.

  20. 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…

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. A simple photoionization scheme for characterizing electron and ion spectrometers

    NASA Astrophysics Data System (ADS)

    Wituschek, A.; von Vangerow, J.; Grzesiak, J.; Stienkemeier, F.; Mudrich, M.

    2016-08-01

    We present a simple diode laser-based photoionization scheme for generating electrons and ions with well-defined spatial and energetic (≲2 eV) structures. This scheme can easily be implemented in ion or electron imaging spectrometers for the purpose of off-line characterization and calibration. The low laser power ˜1 mW needed from a passively stabilized diode laser and the low flux of potassium atoms in an effusive beam make our scheme a versatile source of ions and electrons for applications in research and education.

  17. On the Conservation and Convergence to Weak Solutions of Global Schemes

    NASA Technical Reports Server (NTRS)

    Carpenter, Mark H.; Gottlieb, David; Shu, Chi-Wang

    2001-01-01

    In this paper we discuss the issue of conservation and convergence to weak solutions of several global schemes, including the commonly used compact schemes and spectral collocation schemes, for solving hyperbolic conservation laws. It is shown that such schemes, if convergent boundedly almost everywhere, will converge to weak solutions. The results are extensions of the classical Lax-Wendroff theorem concerning conservative schemes.

  18. A Computer Oriented Scheme for Coding Chemicals in the Field of Biomedicine.

    ERIC Educational Resources Information Center

    Bobka, Marilyn E.; Subramaniam, J.B.

    The chemical coding scheme of the Medical Coding Scheme (MCS), developed for use in the Comparative Systems Laboratory (CSL), is outlined and evaluated in this report. The chemical coding scheme provides a classification scheme and encoding method for drugs and chemical terms. Using the scheme complicated chemical structures may be expressed…

  19. Explicit Von Neumann Stability Conditions for the c-tau Scheme: A Basic Scheme in the Development of the CE-SE Courant Number Insensitive Schemes

    NASA Technical Reports Server (NTRS)

    Chang, Sin-Chung

    2005-01-01

    As part of the continuous development of the space-time conservation element and solution element (CE-SE) method, recently a set of so call ed "Courant number insensitive schemes" has been proposed. The key advantage of these new schemes is that the numerical dissipation associa ted with them generally does not increase as the Courant number decre ases. As such, they can be applied to problems with large Courant number disparities (such as what commonly occurs in Navier-Stokes problem s) without incurring excessive numerical dissipation.

  20. A pilot evaluation of two G-seat cueing schemes

    NASA Technical Reports Server (NTRS)

    Showalter, T. W.

    1978-01-01

    A comparison was made of two contrasting G-seat cueing schemes. The G-seat, an aircraft simulation subsystem, creates aircraft acceleration cues via seat contour changes. Of the two cueing schemes tested, one was designed to create skin pressure cues and the other was designed to create body position cues. Each cueing scheme was tested and evaluated subjectively by five pilots regarding its ability to cue the appropriate accelerations in each of four simple maneuvers: a pullout, a pushover, an S-turn maneuver, and a thrusting maneuver. A divergence of pilot opinion occurred, revealing that the perception and acceptance of G-seat stimuli is a highly individualistic phenomena. The creation of one acceptable G-seat cueing scheme was, therefore, deemed to be quite difficult.

  1. DISGUISED IN AN OCEANIC CAMOUFLAGE PAINT SCHEME, EVERGREEN MAKES HER ...

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

    DISGUISED IN AN OCEANIC CAMOUFLAGE PAINT SCHEME, EVERGREEN MAKES HER WAY THROUGH THE NORTH ATLANTIC DURING WORLD WAR II. HER 3" GUN IS VISIBLE BEHIND THE STACK - U.S. Coast Guard Cutter EVERGREEN, New London, New London County, CT

  2. Scheme for teleportation of quantum states onto a mechanical resonator.

    PubMed

    Mancini, Stefano; Vitali, David; Tombesi, Paolo

    2003-04-04

    We propose an experimentally feasible scheme to teleport an unkown quantum state onto the vibrational degree of freedom of a macroscopic mirror. The quantum channel between the two parties is established by exploiting radiation pressure effects.

  3. A blind reversible robust watermarking scheme for relational databases.

    PubMed

    Chang, Chin-Chen; Nguyen, Thai-Son; Lin, Chia-Chen

    2013-01-01

    Protecting the ownership and controlling the copies of digital data have become very important issues in Internet-based applications. Reversible watermark technology allows the distortion-free recovery of relational databases after the embedded watermark data are detected or verified. In this paper, we propose a new, blind, reversible, robust watermarking scheme that can be used to provide proof of ownership for the owner of a relational database. In the proposed scheme, a reversible data-embedding algorithm, which is referred to as "histogram shifting of adjacent pixel difference" (APD), is used to obtain reversibility. The proposed scheme can detect successfully 100% of the embedded watermark data, even if as much as 80% of the watermarked relational database is altered. Our extensive analysis and experimental results show that the proposed scheme is robust against a variety of data attacks, for example, alteration attacks, deletion attacks, mix-match attacks, and sorting attacks.

  4. A Blind Reversible Robust Watermarking Scheme for Relational Databases

    PubMed Central

    Chang, Chin-Chen; Nguyen, Thai-Son; Lin, Chia-Chen

    2013-01-01

    Protecting the ownership and controlling the copies of digital data have become very important issues in Internet-based applications. Reversible watermark technology allows the distortion-free recovery of relational databases after the embedded watermark data are detected or verified. In this paper, we propose a new, blind, reversible, robust watermarking scheme that can be used to provide proof of ownership for the owner of a relational database. In the proposed scheme, a reversible data-embedding algorithm, which is referred to as “histogram shifting of adjacent pixel difference” (APD), is used to obtain reversibility. The proposed scheme can detect successfully 100% of the embedded watermark data, even if as much as 80% of the watermarked relational database is altered. Our extensive analysis and experimental results show that the proposed scheme is robust against a variety of data attacks, for example, alteration attacks, deletion attacks, mix-match attacks, and sorting attacks. PMID:24223033

  5. Splined version of FLEXSTAB: A critical analysis of alternate schemes

    NASA Technical Reports Server (NTRS)

    Weber, J. A.

    1977-01-01

    Recommendations are made for improved aerodynamic models and numerical schemes to be considered for inclusion into the FLEXSTAB computer program system. These recommendations are based on a critical analysis of numerical technology.

  6. Entropy-bounded discontinuous Galerkin scheme for Euler equations

    NASA Astrophysics Data System (ADS)

    Lv, Yu; Ihme, Matthias

    2015-08-01

    An entropy-bounded Discontinuous Galerkin (EBDG) scheme is proposed in which the solution is regularized by constraining the entropy. The resulting scheme is able to stabilize the solution in the vicinity of discontinuities and retains the optimal accuracy for smooth solutions. The properties of the limiting operator according to the entropy-minimum principle are proofed, and an optimal CFL-criterion is derived. We provide a rigorous description for locally imposing entropy constraints to capture multiple discontinuities. Significant advantages of the EBDG-scheme are the general applicability to arbitrary high-order elements and its simple implementation for multi-dimensional configurations. Numerical tests confirm the properties of the scheme, and particular focus is attributed to the robustness in treating discontinuities on arbitrary meshes.

  7. Unification of some advection schemes in two dimensions

    NASA Technical Reports Server (NTRS)

    Sidilkover, D.; Roe, P. L.

    1995-01-01

    The relationship between two approaches towards construction of genuinely two-dimensional upwind advection schemes is established. One of these approaches is of the control volume type applicable on structured cartesian meshes. It resulted in the compact high resolution schemes capable of maintaining second order accuracy in both homogeneous and inhomogeneous cases. Another one is the fluctuation splitting approach, which is well suited for triangular (and possibly) unstructured meshes. Understanding the relationship between these two approaches allows us to formulate here a new fluctuation splitting high resolution (i.e. possible use of artificial compression, while maintaining positivity property) scheme. This scheme is shown to be linearity preserving in inhomogeneous as well as homogeneous cases.

  8. Renormalization-scheme-invariant perturbation theory: Miracle or mirage

    SciTech Connect

    Chyla, J.

    1985-05-15

    A recently proposed solution to the renormalization-scheme ambiguity in perturbation theory is critically analyzed and shown to possess another kind of ambiguity closely related to the one it is supposed to cure.

  9. Factorizable Schemes for the Equations of Fluid Flow

    NASA Technical Reports Server (NTRS)

    Sidilkover, David

    1999-01-01

    We present an upwind high-resolution factorizable (UHF) discrete scheme for the compressible Euler equations that allows to distinguish between full-potential and advection factors at the discrete level. The scheme approximates equations in their general conservative form and is related to the family of genuinely multidimensional upwind schemes developed previously and demonstrated to have good shock-capturing capabilities. A unique property of this scheme is that in addition to the aforementioned features it is also factorizable, i.e., it allows to distinguish between full-potential and advection factors at the discrete level. The latter property facilitates the construction of optimally efficient multigrid solvers. This is done through a relaxation procedure that utilizes the factorizability property.

  10. Lighten Encryption Schemes for Secure and Private RFID Systems

    NASA Astrophysics Data System (ADS)

    Canard, Sébastien; Coisel, Iwen; Etrog, Jonathan

    We provide several concrete implementations of a generic method given by Vaudenay to construct secure privacy-preserving RFID authentication and identification systems. More precisely, we give the first instantiation of the Vaudenay's result by using the IND-CCA secure DHAES cryptosystem. Next we argue that weaker cryptosystems can also be used by recalling the WIPR RFID system and giving a new protocol based on the El Gamal encryption scheme. After that, we introduce a new generic construction based on the use of any IND-CPA secure public key cryptosystem together with a MAC scheme and describe a possibility using the Hash El Gamal cryptosystem. We finally compare all these schemes, both in terms of implementation and security, proving that, nowadays the DHAES and our Hash El Gamal based solutions appear as the most promising schemes.

  11. OFDM-PWM scheme for visible light communications

    NASA Astrophysics Data System (ADS)

    Zhang, Tian; Ghassemlooy, Zabih; Rajbhandari, Sujan; Popoola, Wasiu O.; Guo, Shuxu

    2017-02-01

    In this paper, we propose an improved hybrid optical orthogonal frequency division multiplexing (O-OFDM) and pulse-width modulation (PWM) scheme for visible light communications. In this scheme, a bipolar O-OFDM signal is converted into a PWM format where the leading and trailing edges convey the frame synchronization and modulated information, respectively. The proposed scheme is insensitive to the non-linearity of the light emitting diode (LED) as LEDs are switched 'on' and 'off' between two points. Therefore, the tight requirement on the high peak-to-average-power-ratio (PAPR) in O-OFDM is no longer a major issue. The simulation and experimental results demonstrate that the proposed scheme offers an improved bit error rate performance compared to the traditional asymmetrically clipped O-OFDM (ACO-OFDM).

  12. Auxiliary power controls on the Nelson River HVDC scheme

    SciTech Connect

    Chand, J. )

    1992-02-01

    This paper describes the auxiliary power controls on the Nelson River HVDC scheme. It shows how the fast control feature of the HVDC link can be utilized to enhance the operation of an integrated ac/dc power system.

  13. Efficient scheme for parametric fitting of data in arbitrary dimensions.

    PubMed

    Pang, Ning-Ning; Tzeng, Wen-Jer; Kao, Hisen-Ching

    2008-07-01

    We propose an efficient scheme for parametric fitting expressed in terms of the Legendre polynomials. For continuous systems, our scheme is exact and the derived explicit expression is very helpful for further analytical studies. For discrete systems, our scheme is almost as accurate as the method of singular value decomposition. Through a few numerical examples, we show that our algorithm costs much less CPU time and memory space than the method of singular value decomposition. Thus, our algorithm is very suitable for a large amount of data fitting. In addition, the proposed scheme can also be used to extract the global structure of fluctuating systems. We then derive the exact relation between the correlation function and the detrended variance function of fluctuating systems in arbitrary dimensions and give a general scaling analysis.

  14. Experiments with a Class of Nonlinear Anti-Diffusion Schemes

    NASA Astrophysics Data System (ADS)

    Moini-Yekta, Shayan

    The use of artificial viscosity in the simulation of viscous flows with separation, as well as inviscid flows with shocks is demonstrated first, based on standard central difference schemes. The effects of a class of nonlinear anti-diffusion schemes are studied. Furthermore, the anti-diffusion scheme is used to simulate turbulent flows over a flat plate and an ellipse, based on a primitive variable formulation in curvilinear coordinates and the artificial compressibility method. Both Baldwin-Lomax and Spalart-Allamaras models are implemented and the results are compared to those of the NASA CFL3D code. The results based on the anti-diffusion scheme are encouraging as third order upwinding results are recovered with first order upwinding with anti-diffusion.

  15. Embedded WENO: A design strategy to improve existing WENO schemes

    NASA Astrophysics Data System (ADS)

    van Lith, Bart S.; ten Thije Boonkkamp, Jan H. M.; IJzerman, Wilbert L.

    2017-02-01

    Embedded WENO methods utilise all adjacent smooth substencils to construct a desirable interpolation. Conventional WENO schemes under-use this possibility close to large gradients or discontinuities. We develop a general approach for constructing embedded versions of existing WENO schemes. Embedded methods based on the WENO schemes of Jiang and Shu [1] and on the WENO-Z scheme of Borges et al. [2] are explicitly constructed. Several possible choices are presented that result in either better spectral properties or a higher order of convergence for sufficiently smooth solutions. However, these improvements carry over to discontinuous solutions. The embedded methods are demonstrated to be indeed improvements over their standard counterparts by several numerical examples. All the embedded methods presented have no added computational effort compared to their standard counterparts.

  16. Uniform algorithm for all-speed shock-capturing schemes

    NASA Astrophysics Data System (ADS)

    Li, Xue-song

    2014-07-01

    Many ideas exist for the development of shock-capturing schemes, such as Roe, Harten-Lax-van Leer (HLL) and advection upstream splitting method (AUSM) families, and their extension for all-speed flow. A uniform algorithm that expresses the three families in the same framework is proposed in this study. The algorithm has an explicit physical meaning, provides new understanding and comparison of the mechanism of schemes, and may play a significant role in further research. As an example of applying the uniform algorithm, the low Mach number behaviour of the schemes is analysed. A clear and simple explanation is provided based on the wall boundary, and a concise rule is proposed to determine whether a scheme has satisfied low Mach number behaviour.

  17. Design of optimally smoothing multistage schemes for the Euler equations

    NASA Technical Reports Server (NTRS)

    Van Leer, Bram; Lee, Wen-Tzong; Roe, Philip L.; Powell, Kenneth G.; Tai, Chang-Hsien

    1992-01-01

    A recently derived local preconditioning of the Euler equations is shown to be useful in developing multistage schemes suited for multigrid use. The effect of the preconditioning matrix on the spatial Euler operator is to equalize the characteristic speeds. When applied to the discretized Euler equations, the preconditioning has the effect of strongly clustering the operator's eigenvalues in the complex plane. This makes possible the development of explicit marching schemes that effectively damp most high-frequency Fourier modes, as desired in multigrid applications. The technique is the same as developed earlier for scalar convection schemes: placement of the zeros of the amplification factor of the multistage scheme in locations where eigenvalues corresponding to high-frequency modes abound.

  18. The effectiveness of Hong Kong's Construction Waste Disposal Charging Scheme.

    PubMed

    Hao, Jane L; Hills, Martin J; Tam, Vivian W Y

    2008-12-01

    The Hong Kong Government introduced the Construction Waste Disposal Charging Scheme in December 2005 to ensure that disposal of construction and demolition (C&D) waste is properly priced to reduce such waste. The charging scheme is not only intended to provide an economic incentive for contractors and developers to reduce waste but also to encourage reuse and recycling of waste material thereby slowing down the depletion of limited landfill and public filling capacities. This paper examines the effectiveness of the charging scheme 1 year after implementation. A survey was conducted at Tseung Kwan O Area 137 and Tuen Mun Area 38, and daily C&D waste records were collected from landfills and public filling facilities between January 2006 and December 2006. The results of the survey show that waste has been reduced by approximately 60% in landfills, by approximately 23% in public fills, and by approximately 65% in total waste between 2005 and 2006. Suggestions for improving the scheme are provided.

  19. Development of Dam Operation Scheme in a Hydrology Model

    NASA Astrophysics Data System (ADS)

    He, Y.; Liang, X.

    2013-12-01

    A novel scheme for dam operation has been developed based on the artificial neural network approach to predict the reservoir management and hydrologic effects in response to climate variation and change. The scheme is built upon the historic management information of operating each dam, including climate, ecology properties and attributes (e.g., storage, surface area) for all relevant reservoirs. The scheme implicitly introduces the relationship between water demand and supply for downstream fluvial ecosystem, agriculture irrigation, and hydropower. This study will first present the fundamental formulation of the predictive scheme along with detailed analysis of the historical management data, and then evaluate the performance for its application in the Colorado River basin. Caveats and merits will also be discussed.

  20. Gearbox fault diagnosis using adaptive redundant Lifting Scheme

    NASA Astrophysics Data System (ADS)

    Hongkai, Jiang; Zhengjia, He; Chendong, Duan; Peng, Chen

    2006-11-01

    Vibration signals acquired from a gearbox usually are complex, and it is difficult to detect the symptoms of an inherent fault in a gearbox. In this paper, an adaptive redundant lifting scheme for the fault diagnosis of gearboxes is developed. It adopts data-based optimisation algorithm to lock on to the dominant structure of the signal, and well reveal the transient components of the vibration signal in time domain. Both lifting scheme and adaptive redundant lifting scheme are applied to analyse the experimental signal from a gearbox with wear fault and the practical vibration signal from a large air compressor. The results confirm that adaptive redundant lifting scheme is quite effective in extracting impulse and modulation feature components from the complex background.

  1. Modulation scheme for electron-electron double resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Mehlkopf, A. F.; Kuiper, F. G.; Smidt, J.; Tiggelman, T. A.

    1983-06-01

    A modulation scheme for electron-electron double resonance (ELDOR) spectrometers is presented. With this scheme an optimum stabilization signal for locking the pump microwave generator to the pumped electron paramagnetic resonance (EPR) line is generated. A separate pump power level and a separate magnetic field modulation amplitude are used for the purpose of locking. In general, such a modulation scheme introduces false ELDOR lines. These false lines disturb the real ELDOR signals, or introduce an ELDOR signal in the absence of any communication between the observed EPR line and the pumped EPR line. With the described modulation scheme the frequencies of the false ELDOR signals are limited to even multiples of the frequency of the wanted ELDOR signals. This makes a suppression of the false ELDOR lines easy.

  2. Robust entanglement via optomechanical dark mode: adiabatic scheme

    NASA Astrophysics Data System (ADS)

    Tian, Lin; Wang, Ying-Dan; Huang, Sumei; Clerk, Aashish

    2013-03-01

    Entanglement is a powerful resource for studying quantum effects in macroscopic objects and for quantum information processing. Here, we show that robust entanglement between cavity modes with distinct frequencies can be generated via a mechanical dark mode in an optomechanical quantum interface. Due to quantum interference, the effect of the mechanical noise is cancelled in a way that is similar to the electromagnetically induced transparency. We derive the entanglement in the strong coupling regime by solving the quantum Langevin equation using a perturbation theory approach. The entanglement in the adiabatic scheme is then compared with the entanglement in the stationary state scheme. Given the robust entanglement schemes and our previous schemes on quantum wave length conversion, the optomechanical interface hence forms an effective building block for a quantum network. This work is supported by DARPA-ORCHID program, NSF-DMR-0956064, NSF-CCF-0916303, and NSF-COINS.

  3. Robust event detection scheme for complex scenes in video surveillance

    NASA Astrophysics Data System (ADS)

    Chen, Erkang; Xu, Yi; Yang, Xiaokang; Zhang, Wenjun

    2011-07-01

    Event detection for video surveillance is a difficult task due to many challenges: cluttered background, illumination variations, scale variations, occlusions among people, etc. We propose an effective and efficient event detection scheme in such complex situations. Moving shadows due to illumination are tackled with a segmentation method with shadow detection, and scale variations are taken care of using the CamShift guided particle filter tracking algorithm. For event modeling, hidden Markov models are employed. The proposed scheme also reduces the overall computational cost by combing two human detection algorithms and using tracking information to aid human detection. Experimental results on TRECVid event detection evaluation demonstrate the efficacy of the proposed scheme. It is robust, especially to moving shadows and scale variations. Employing the scheme, we achieved the best run results for two events in the TRECVid benchmarking evaluation.

  4. Interpolation-Free Scanning And Sampling Scheme For Tomographic Reconstructions

    NASA Astrophysics Data System (ADS)

    Donohue, K. D.; Saniie, J.

    1987-01-01

    In this paper a sampling scheme is developed for computer tomography (CT) systems that eliminates the need for interpolation. A set of projection angles along with their corresponding sampling rates are derived from the geometry of the Cartesian grid such that no interpolation is required to calculate the final image points for the display grid. A discussion is presented on the choice of an optimal set of projection angles that will maintain a resolution comparable to a sampling scheme of regular measurement geometry, while minimizing the computational load. The interpolation-free scanning and sampling (IFSS) scheme developed here is compared to a typical sampling scheme of regular measurement geometry through a computer simulation.

  5. High-performance multicasting schemes in optical packet switched networks

    NASA Astrophysics Data System (ADS)

    Ji, Yuefeng; Liu, Xin; Zhang, Jie; Zhang, Min

    2009-11-01

    Current trends in communications indicate that multicasting is becoming increasingly popular and important in networking applications. Since multicasting can be supported more efficiently in optical domain by utilizing the inherent light-splitting capacity of optical devices, such as optical splitters, than by copying data in electronic domain, issues concerning running multicast sessions in the all-optical networks have received much attention in recent years. In this paper, different multicasting schemes and their performance in the Optical Packet Switched networks are investigated, including the parallel mode, serial mode, and hybrid mode multicasting schemes. Computer simulation results show that compared with the parallel-mode and serial-mode multicasting schemes, hybrid-mode multicasting scheme is the best way to deliver multicast sessions in the Optical Packet Switched networks due to its highest performance.

  6. 7 CFR 1424.13 - Misrepresentation and scheme or device.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS BIOENERGY PROGRAM § 1424.13... misrepresentation, scheme, or device, or to any other person as a result of the bioenergy producer's actions,...

  7. 7 CFR 1424.13 - Misrepresentation and scheme or device.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS BIOENERGY PROGRAM § 1424.13... misrepresentation, scheme, or device, or to any other person as a result of the bioenergy producer's actions,...

  8. 7 CFR 1424.13 - Misrepresentation and scheme or device.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS BIOENERGY PROGRAM § 1424.13... misrepresentation, scheme, or device, or to any other person as a result of the bioenergy producer's actions,...

  9. 7 CFR 1424.13 - Misrepresentation and scheme or device.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS BIOENERGY PROGRAM § 1424.13... misrepresentation, scheme, or device, or to any other person as a result of the bioenergy producer's actions,...

  10. 7 CFR 1424.13 - Misrepresentation and scheme or device.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS BIOENERGY PROGRAM § 1424.13... misrepresentation, scheme, or device, or to any other person as a result of the bioenergy producer's actions,...

  11. High order accurate finite difference schemes based on symmetry preservation

    NASA Astrophysics Data System (ADS)

    Ozbenli, Ersin; Vedula, Prakash

    2016-11-01

    A new algorithm for development of high order accurate finite difference schemes for numerical solution of partial differential equations using Lie symmetries is presented. Considering applicable symmetry groups (such as those relevant to space/time translations, Galilean transformation, scaling, rotation and projection) of a partial differential equation, invariant numerical schemes are constructed based on the notions of moving frames and modified equations. Several strategies for construction of invariant numerical schemes with a desired order of accuracy are analyzed. Performance of the proposed algorithm is demonstrated using analysis of one-dimensional partial differential equations, such as linear advection diffusion equations inviscid Burgers equation and viscous Burgers equation, as our test cases. Through numerical simulations based on these examples, the expected improvement in accuracy of invariant numerical schemes (up to fourth order) is demonstrated. Advantages due to implementation and enhanced computational efficiency inherent in our proposed algorithm are presented. Extension of the basic framework to multidimensional partial differential equations is also discussed.

  12. Factors affecting sustainability of rural water schemes in Swaziland

    NASA Astrophysics Data System (ADS)

    Peter, Graciana; Nkambule, Sizwe E.

    The Millennium Development Goal (MDG) target to reduce the proportion of people without sustainable access to safe drinking water by the year 2015 has been met as of 2010, but huge disparities exist. Some regions, particularly Sub-Saharan Africa are lagging behind it is also in this region where up to 30% of the rural schemes are not functional at any given time. There is need for more studies on factors affecting sustainability and necessary measures which when implemented will improve the sustainability of rural water schemes. The main objective of this study was to assess the main factors affecting the sustainability of rural water schemes in Swaziland using a Multi-Criteria Analysis Approach. The main factors considered were: financial, social, technical, environmental and institutional. The study was done in Lubombo region. Fifteen functional water schemes in 11 communities were studied. Data was collected using questionnaires, checklist and focused group discussion guide. A total of 174 heads of households were interviewed. Statistical Package for Social Sciences (SPSS) was used to analyse the data and to calculate sustainability scores for water schemes. SPSS was also used to classify sustainability scores according to sustainability categories: sustainable, partially sustainable and non-sustainable. The averages of the ratings for the different sub-factors studied and the results on the sustainability scores for the sustainable, partially sustainable and non-sustainable schemes were then computed and compared to establish the main factors influencing sustainability of the water schemes. The results indicated technical and social factors as most critical while financial and institutional, although important, played a lesser role. Factors which contributed to the sustainability of water schemes were: functionality; design flow; water fetching time; ability to meet additional demand; use by population; equity; participation in decision making on operation and

  13. Efficient Low Dissipative High Order Schemes for Multiscale MHD Flows

    NASA Technical Reports Server (NTRS)

    Sjoegreen, Bjoern; Yee, Helen C.; Mansour, Nagi (Technical Monitor)

    2002-01-01

    Accurate numerical simulations of complex multiscale compressible viscous flows, especially high speed turbulence combustion and acoustics, demand high order schemes with adaptive numerical dissipation controls. Standard high resolution shock-capturing methods are too dissipative to capture the small scales and/or long-time wave propagations without extreme grid refinements and small time steps. An integrated approach for the control of numerical dissipation in high order schemes for the compressible Euler and Navier-Stokes equations has been developed and verified by the authors and collaborators. These schemes are suitable for the problems in question. Basically, the scheme consists of sixth-order or higher non-dissipative spatial difference operators as the base scheme. To control the amount of numerical dissipation, multiresolution wavelets are used as sensors to adaptively limit the amount and to aid the selection and/or blending of the appropriate types of numerical dissipation to be used. Magnetohydrodynamics (MHD) waves play a key role in drag reduction in highly maneuverable high speed combat aircraft, in space weather forecasting, and in the understanding of the dynamics of the evolution of our solar system and the main sequence stars. Although there exist a few well-studied second and third-order high-resolution shock-capturing schemes for the MHD in the literature, these schemes are too diffusive and not practical for turbulence/combustion MHD flows. On the other hand, extension of higher than third-order high-resolution schemes to the MHD system of equations is not straightforward. Unlike the hydrodynamic equations, the inviscid MHD system is non-strictly hyperbolic with non-convex fluxes. The wave structures and shock types are different from their hydrodynamic counterparts. Many of the non-traditional hydrodynamic shocks are not fully understood. Consequently, reliable and highly accurate numerical schemes for multiscale MHD equations pose a great

  14. An expert system based intelligent control scheme for space bioreactors

    NASA Technical Reports Server (NTRS)

    San, Ka-Yiu

    1988-01-01

    An expert system based intelligent control scheme is being developed for the effective control and full automation of bioreactor systems in space. The scheme developed will have the capability to capture information from various resources including heuristic information from process researchers and operators. The knowledge base of the expert system should contain enough expertise to perform on-line system identification and thus be able to adapt the controllers accordingly with minimal human supervision.

  15. Arbitrated quantum signature scheme based on cluster states

    NASA Astrophysics Data System (ADS)

    Yang, Yu-Guang; Lei, He; Liu, Zhi-Chao; Zhou, Yi-Hua; Shi, Wei-Min

    2016-06-01

    Cluster states can be exploited for some tasks such as topological one-way computation, quantum error correction, teleportation and dense coding. In this paper, we investigate and propose an arbitrated quantum signature scheme with cluster states. The cluster states are used for quantum key distribution and quantum signature. The proposed scheme can achieve an efficiency of 100 %. Finally, we also discuss its security against various attacks.

  16. A fuzzy structural matching scheme for space robotics vision

    NASA Technical Reports Server (NTRS)

    Naka, Masao; Yamamoto, Hiromichi; Homma, Khozo; Iwata, Yoshitaka

    1994-01-01

    In this paper, we propose a new fuzzy structural matching scheme for space stereo vision which is based on the fuzzy properties of regions of images and effectively reduces the computational burden in the following low level matching process. Three dimensional distance images of a space truss structural model are estimated using this scheme from stereo images sensed by Charge Coupled Device (CCD) TV cameras.

  17. A Trivariate Clough-Tocher Scheme for Tetrahedral Data.

    DTIC Science & Technology

    1984-06-01

    data, for arbitrary m and in arbitrarily many variables. However, all of the existing tetrahedral schemes yield rational interpolants . One would like...from the cardinal properties of barycentric coordinates that =bk 6 5 _ bki (2.3) where 6 is the Kronecker delta. The piecewise cubic interpolant (on a...1984 Abstract -An interpolation scheme is described for values of position, gradient and Hessian at scattered points in three variables. The domain is

  18. Central Schemes for Multi-Dimensional Hamilton-Jacobi Equations

    NASA Technical Reports Server (NTRS)

    Bryson, Steve; Levy, Doron; Biegel, Bryan (Technical Monitor)

    2002-01-01

    We present new, efficient central schemes for multi-dimensional Hamilton-Jacobi equations. These non-oscillatory, non-staggered schemes are first- and second-order accurate and are designed to scale well with an increasing dimension. Efficiency is obtained by carefully choosing the location of the evolution points and by using a one-dimensional projection step. First-and second-order accuracy is verified for a variety of multi-dimensional, convex and non-convex problems.

  19. CONDIF - A modified central-difference scheme for convective flows

    NASA Technical Reports Server (NTRS)

    Runchal, Akshai K.

    1987-01-01

    The paper presents a method, called CONDIF, which modifies the CDS (central-difference scheme) by introducing a controlled amount of numerical diffusion based on the local gradients. The numerical diffusion can be adjusted to be negligibly low for most problems. CONDIF results are significantly more accurate than those obtained from the hybrid scheme when the Peclet number is very high and the flow is at large angles to the grid.

  20. Collaborative Protection and Control Schemes for Shipboard Electrical Systems

    DTIC Science & Technology

    2007-03-26

    Based System Protection The envisioned scheme uses the converters (which are voltage source type) as switches ( circuit breakers ) to limit and interrupt...use of VSC as CB ( circuit breaker ) is significant, mainly: i) It eliminates the need to use separate circuit breakers that need to be developed...this fast acting VSC based circuit breakers however introduces a new challenge, that the protection scheme should be able to detect and locate the

  1. HARM: A Numerical Scheme for General Relativistic Magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Gammie, Charles, F.; McKinney, Jonathan C.; Tóth, Gábor

    2012-09-01

    HARM uses a conservative, shock-capturing scheme for evolving the equations of general relativistic magnetohydrodynamics. The fluxes are calculated using the Harten, Lax, & van Leer scheme. A variant of constrained transport, proposed earlier by Tóth, is used to maintain a divergence-free magnetic field. Only the covariant form of the metric in a coordinate basis is required to specify the geometry. On smooth flows HARM converges at second order.

  2. On the dynamics of some grid adaption schemes

    NASA Technical Reports Server (NTRS)

    Sweby, Peter K.; Yee, Helen C.

    1994-01-01

    The dynamics of a one-parameter family of mesh equidistribution schemes coupled with finite difference discretisations of linear and nonlinear convection-diffusion model equations is studied numerically. It is shown that, when time marched to steady state, the grid adaption not only influences the stability and convergence rate of the overall scheme, but can also introduce spurious dynamics to the numerical solution procedure.

  3. Direct plasma injection scheme with various ion beams

    SciTech Connect

    Okamura, M.

    2010-09-15

    The laser ion source is one of the most powerful heavy ion sources. However, it is difficult to obtain good stability and to control its intense current. To overcome these difficulties, we proposed a new beam injection scheme called 'direct plasma injection scheme'. Following this it was established to provide various species with desired charge state as an intense accelerated beam. Carbon, aluminum and iron beams have been tested.

  4. Stability of explicit advection schemes. The balance point location rule

    NASA Astrophysics Data System (ADS)

    Leonard, B. P.

    2002-02-01

    This paper introduces the balance point location rule, providing specific necessary and sufficient conditions for constructing unconditionally stable explicit advection schemes, in both semi-Lagrangian and flux-form Eulerian formulations. The rule determines how the spatial stencil is placed on the computational grid. It requires the balance point (the center of the stencil in index space) to be located in the same patch as the departure point for semi-Lagrangian schemes or the same cell as the sweep point for Eulerian schemes. Centering the stencil in this way guarantees stability, regardless of the size of the time step. In contrast, the original Courant-Friedrichs-Lewy (CFL) condition requiring the stencil merely to include the departure (sweep) point, although necessary, is not sufficient for guaranteeing stability. The CFL condition is of limited practical value, whereas the balance point location rule always gives precise and easily implemented prescriptions for constructing stable algorithms. The rule is also helpful in correcting a number of misconceptions that have arisen concerning explicit advection schemes. In particular, explicit Eulerian schemes are widely believed to be inefficient because of stability constraints on the time step, dictated by a narrow interpretation of the CFL condition requiring the Courant number to be less than or equal to one. However, such constraints apply only to a particular class of advection schemes resulting for centering the stencil on the arrival point, when in fact the sole function of the stencil is to estimate the departure (sweep) point value - the arrival point has no relevance in determining the placement of the stencil. Unconditionally stable explicit Eulerian advection schemes are efficient and accurate, comparable in operation count to semi-Lagrangian schemes of the same order, but because of their flux-based formulation, they have the added advantage of being inherently conservative. Copyright

  5. The Effect of the Weight Scheme on DFT Vibrational Frequencies

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles; Ricca, Alessandra

    1999-01-01

    All-electron B3LYP harmonic frequencies of Ge2H5 and Ge2H6 are computed for several choices of grid and using both the Becke and the Stratmann, Scuseria, and Frisch atomic partition functions (weight scheme). For large grids, the results are independent of the weighting scheme. The lowest frequency mode is much more stable with respect to the number of grid points when the Stratmann, Scuseria, and Frisch weights are used.

  6. The standard upwind compact difference schemes for incompressible flow simulations

    NASA Astrophysics Data System (ADS)

    Fan, Ping

    2016-10-01

    Compact difference schemes have been used extensively for solving the incompressible Navier-Stokes equations. However, the earlier formulations of the schemes are of central type (called central compact schemes, CCS), which are dispersive and susceptible to numerical instability. To enhance stability of CCS, the optimal upwind compact schemes (OUCS) are developed recently by adding high order dissipative terms to CCS. In this paper, it is found that OUCS are essentially not of the upwind type because they do not use upwind-biased but central type of stencils. Furthermore, OUCS are not the most optimal since orders of accuracy of OUCS are at least one order lower than the maximum achievable orders. New upwind compact schemes (called standard upwind compact schemes, SUCS) are developed in this paper. In contrast to OUCS, SUCS are constructed based completely on upwind-biased stencils and hence can gain adequate numerical dissipation with no need for introducing optimization calculations. Furthermore, SUCS can achieve the maximum achievable orders of accuracy and hence be more compact than OUCS. More importantly, SUCS have prominent advantages on combining the stable and high resolution properties which are demonstrated from the global spectral analyses and typical numerical experiments.

  7. A class of difference schemes with flexible local approximation

    SciTech Connect

    Tsukerman, Igor . E-mail: igor@uakron.edu

    2006-01-20

    Solutions of many physical problems have salient local features that are qualitatively known a priori (for example, singularities at point sources, edge and corners; boundary layers; derivative jumps at material interfaces; strong dipole field components near polarized spherical particles; cusps of electronic wavefunctions at the nuclei; electrostatic double layers around colloidal particles, etc.) The known methods capable of providing flexible local approximation of such features include the generalized finite element - partition of unity method, special variational-difference schemes in broken Sobolev spaces, and a few other specialized techniques. In the proposed new class of Flexible Local Approximation MEthods (FLAME), a desirable set of local approximating functions (such as cylindrical or spherical harmonics, plane waves, harmonic polynomials, etc.) defines a finite difference scheme on a chosen grid stencil. One motivation is to minimize the notorious 'staircase' effect at curved and slanted interface boundaries. However, the new approach has much broader applications. As illustrative examples, the paper presents arbitrarily high order 3-point schemes for the 1D Schroedinger equation and a 1D singular equation, schemes for electrostatic interactions of colloidal particles, electromagnetic wave propagation and scattering, plasmon resonances. Moreover, many classical finite difference schemes, including the Collatz 'Mehrstellen' schemes, are direct particular cases of FLAME.

  8. Control Scheme of Tether Drag Deorbit System in Orbital Plane

    NASA Astrophysics Data System (ADS)

    Cui, Wei-Dong; Sun, Liang; Zhao, Guo-Wei

    In this paper, based on a dumbbell model of tethered satellite, a tension control scheme and a thrust control scheme of tether drag deorbit system in orbital plane are respectively proposed. In the tension control scheme, the tether tension can be measured by tension sensor and controlled by adjusting the tether length with a certain windlass mechanism, so that the librational angles could track the expected value; meanwhile, the tether could come back to the initial value. Because of the windlass mechanism, the slackness of tether can be avoided. In the thrust control scheme, the tether drag deorbit system is with a short tether in orbital maneuvering and the thrust acceleration imposed on the base satellite can be adjusted to avoid the slackness of tether and damp out the librational angles; besides, it is required that the regulation value of thrust acceleration meets with accuracy trajectory in practical engineering. Afterwards, a reasonable deorbit case of an abandoned GEO satellite is studied, in which the control of base satellite is considered; then, the advantages and disadvantages of two control schemes are analyzed and an improved control strategy is given. Numerical simulation results indicate that the slackness of tether can be eliminated and the librational angles are damped out according to the designed controllers, and the stability of the attitude of abandoned satellite is also guaranteed during flight. The proposed control schemes are feasible, which is useful for the flight safety.

  9. Novel Threshold Changeable Secret Sharing Schemes Based on Polynomial Interpolation

    PubMed Central

    Li, Mingchu; Guo, Cheng; Choo, Kim-Kwang Raymond; Ren, Yizhi

    2016-01-01

    After any distribution of secret sharing shadows in a threshold changeable secret sharing scheme, the threshold may need to be adjusted to deal with changes in the security policy and adversary structure. For example, when employees leave the organization, it is not realistic to expect departing employees to ensure the security of their secret shadows. Therefore, in 2012, Zhang et al. proposed (t → t′, n) and ({t1, t2,⋯, tN}, n) threshold changeable secret sharing schemes. However, their schemes suffer from a number of limitations such as strict limit on the threshold values, large storage space requirement for secret shadows, and significant computation for constructing and recovering polynomials. To address these limitations, we propose two improved dealer-free threshold changeable secret sharing schemes. In our schemes, we construct polynomials to update secret shadows, and use two-variable one-way function to resist collusion attacks and secure the information stored by the combiner. We then demonstrate our schemes can adjust the threshold safely. PMID:27792784

  10. Adaptive lifting scheme of wavelet transforms for image compression

    NASA Astrophysics Data System (ADS)

    Wu, Yu; Wang, Guoyin; Nie, Neng

    2001-03-01

    Aiming at the demand of adaptive wavelet transforms via lifting, a three-stage lifting scheme (predict-update-adapt) is proposed according to common two-stage lifting scheme (predict-update) in this paper. The second stage is updating stage. The third is adaptive predicting stage. Our scheme is an update-then-predict scheme that can detect jumps in image from the updated data and it needs not any more additional information. The first stage is the key in our scheme. It is the interim of updating. Its coefficient can be adjusted to adapt to data to achieve a better result. In the adaptive predicting stage, we use symmetric prediction filters in the smooth area of image, while asymmetric prediction filters at the edge of jumps to reduce predicting errors. We design these filters using spatial method directly. The inherent relationships between the coefficients of the first stage and the other stages are found and presented by equations. Thus, the design result is a class of filters with coefficient that are no longer invariant. Simulation result of image coding with our scheme is good.

  11. Asymptotic Diffusion-Limit Accuracy of Sn Angular Differencing Schemes

    SciTech Connect

    Bailey, T S; Morel, J E; Chang, J H

    2009-11-05

    In a previous paper, Morel and Montry used a Galerkin-based diffusion analysis to define a particular weighted diamond angular discretization for S{sub n}n calculations in curvilinear geometries. The weighting factors were chosen to ensure that the Galerkin diffusion approximation was preserved, which eliminated the discrete-ordinates flux dip. It was also shown that the step and diamond angular differencing schemes, which both suffer from the flux dip, do not preserve the diffusion approximation in the Galerkin sense. In this paper we re-derive the Morel and Montry weighted diamond scheme using a formal asymptotic diffusion-limit analysis. The asymptotic analysis yields more information than the Galerkin analysis and demonstrates that the step and diamond schemes do in fact formally preserve the diffusion limit to leading order, while the Morel and Montry weighted diamond scheme preserves it to first order, which is required for full consistency in this limit. Nonetheless, the fact that the step and diamond differencing schemes preserve the diffusion limit to leading order suggests that the flux dip should disappear as the diffusion limit is approached for these schemes. Computational results are presented that confirm this conjecture. We further conjecture that preserving the Galerkin diffusion approximation is equivalent to preserving the asymptotic diffusion limit to first order.

  12. Attack and improvements of fair quantum blind signature schemes

    NASA Astrophysics Data System (ADS)

    Zou, Xiangfu; Qiu, Daowen

    2013-06-01

    Blind signature schemes allow users to obtain the signature of a message while the signer learns neither the message nor the resulting signature. Therefore, blind signatures have been used to realize cryptographic protocols providing the anonymity of some participants, such as: secure electronic payment systems and electronic voting systems. A fair blind signature is a form of blind signature which the anonymity could be removed with the help of a trusted entity, when this is required for legal reasons. Recently, a fair quantum blind signature scheme was proposed and thought to be safe. In this paper, we first point out that there exists a new attack on fair quantum blind signature schemes. The attack shows that, if any sender has intercepted any valid signature, he (she) can counterfeit a valid signature for any message and can not be traced by the counterfeited blind signature. Then, we construct a fair quantum blind signature scheme by improved the existed one. The proposed fair quantum blind signature scheme can resist the preceding attack. Furthermore, we demonstrate the security of the proposed fair quantum blind signature scheme and compare it with the other one.

  13. Novel Threshold Changeable Secret Sharing Schemes Based on Polynomial Interpolation.

    PubMed

    Yuan, Lifeng; Li, Mingchu; Guo, Cheng; Choo, Kim-Kwang Raymond; Ren, Yizhi

    2016-01-01

    After any distribution of secret sharing shadows in a threshold changeable secret sharing scheme, the threshold may need to be adjusted to deal with changes in the security policy and adversary structure. For example, when employees leave the organization, it is not realistic to expect departing employees to ensure the security of their secret shadows. Therefore, in 2012, Zhang et al. proposed (t → t', n) and ({t1, t2,⋯, tN}, n) threshold changeable secret sharing schemes. However, their schemes suffer from a number of limitations such as strict limit on the threshold values, large storage space requirement for secret shadows, and significant computation for constructing and recovering polynomials. To address these limitations, we propose two improved dealer-free threshold changeable secret sharing schemes. In our schemes, we construct polynomials to update secret shadows, and use two-variable one-way function to resist collusion attacks and secure the information stored by the combiner. We then demonstrate our schemes can adjust the threshold safely.

  14. 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

  15. Development of advanced control schemes for telerobot manipulators

    NASA Technical Reports Server (NTRS)

    Nguyen, Charles C.; Zhou, Zhen-Lei

    1991-01-01

    To study space applications of telerobotics, Goddard Space Flight Center (NASA) has recently built a testbed composed mainly of a pair of redundant slave arms having seven degrees of freedom and a master hand controller system. The mathematical developments required for the computerized simulation study and motion control of the slave arms are presented. The slave arm forward kinematic transformation is presented which is derived using the D-H notation and is then reduced to its most simplified form suitable for real-time control applications. The vector cross product method is then applied to obtain the slave arm Jacobian matrix. Using the developed forward kinematic transformation and quaternions representation of the slave arm end-effector orientation, computer simulation is conducted to evaluate the efficiency of the Jacobian in converting joint velocities into Cartesian velocities and to investigate the accuracy of the Jacobian pseudo-inverse for various sampling times. In addition, the equivalence between Cartesian velocities and quaternion is also verified using computer simulation. The motion control of the slave arm is examined. Three control schemes, the joint-space adaptive control scheme, the Cartesian adaptive control scheme, and the hybrid position/force control scheme are proposed for controlling the motion of the slave arm end-effector. Development of the Cartesian adaptive control scheme is presented and some preliminary results of the remaining control schemes are presented and discussed.

  16. Unequal error control scheme for dimmable visible light communication systems

    NASA Astrophysics Data System (ADS)

    Deng, Keyan; Yuan, Lei; Wan, Yi; Li, Huaan

    2017-01-01

    Visible light communication (VLC), which has the advantages of a very large bandwidth, high security, and freedom from license-related restrictions and electromagnetic-interference, has attracted much interest. Because a VLC system simultaneously performs illumination and communication functions, dimming control, efficiency, and reliable transmission are significant and challenging issues of such systems. In this paper, we propose a novel unequal error control (UEC) scheme in which expanding window fountain (EWF) codes in an on-off keying (OOK)-based VLC system are used to support different dimming target values. To evaluate the performance of the scheme for various dimming target values, we apply it to H.264 scalable video coding bitstreams in a VLC system. The results of the simulations that are performed using additive white Gaussian noises (AWGNs) with different signal-to-noise ratios (SNRs) are used to compare the performance of the proposed scheme for various dimming target values. It is found that the proposed UEC scheme enables earlier base layer recovery compared to the use of the equal error control (EEC) scheme for different dimming target values and therefore afford robust transmission for scalable video multicast over optical wireless channels. This is because of the unequal error protection (UEP) and unequal recovery time (URT) of the EWF code in the proposed scheme.

  17. Comparisons of TVD schemes applied to the Navier-Stokes equations. [total variation diminishing

    NASA Technical Reports Server (NTRS)

    Buelow, Philip E.

    1989-01-01

    In this study, the following total variation diminishing (TVD) schemes for solving the Navier-Stokes equations have been tested: the Chakravarthy and Szema (1985) upwind biased TVD scheme, the Harten's upwind TVD scheme described by Yee et al. (1983), and the Yee's (1985) symmetric TVD scheme. The schemes have been compared using three test cases. The first case was the one-dimensional shock tube problem which tested the shock-capturing abilities of the schemes. Chakravarthy's and Harten's schemes gave similar results which were found to be more accurate than the results from Yee's scheme. The second case was a compressible boundary layer which tested the schemes's abilities to solve fiscous flows. In this case, the three schemes yielded almost identical results. Finally, the shock/boundary-layer interaction case studied experimentally by Hakkinen et al. (1959) was computed. Here, Chakravarthy's and Yee's schemes compared most favorably with the published data, with Yee's scheme giving slightly better results.

  18. Contemplation on marking scheme for Type X multiple choice questions, and an illustration of a practically applicable scheme

    PubMed Central

    Siddiqui, Nazeem Ishrat; Bhavsar, Vinayak H.; Bhavsar, Arnav V.; Bose, Sukhwant

    2016-01-01

    Ever since its inception 100 years back, multiple choice items have been widely used as a method of assessment. It has certain inherent limitations such as inability to test higher cognitive skills, element of guesswork while answering, and issues related with marking schemes. Various marking schemes have been proposed in the past but they are not balanced, skewed, and complex, which are based on mathematical calculations which are typically not within the grasp of medical personnel. Type X questions has many advantages being easy to construct, can test multiple concepts/application/facets of a topic, cognitive skill of various level of hierarchy can be tested, and unlike Type K items, they are free from complicated coding. In spite of these advantages, they are not in common use due to complicated marking schemes. This is the reason we explored the aspects of methods of evaluation of multiple correct options multiple choice questions and came up with the simple, practically applicable, nonstringent but logical scoring system for the same. The rationale of the illustrated marking scheme is that it takes into consideration the distracter recognition ability of the examinee rather than relying on the ability only to select the correct response. Thus, examinee's true knowledge is tested, and he is rewarded accordingly for selecting a correct answer and omitting a distracter. The scheme also penalizes for not recognizing a distracter thus controlling guessing behavior. It is emphasized that if the illustrated scoring scheme is adopted, then Type X questions would come in common practice. PMID:27127312

  19. Design and simulation of advanced fault tolerant flight control schemes

    NASA Astrophysics Data System (ADS)

    Gururajan, Srikanth

    This research effort describes the design and simulation of a distributed Neural Network (NN) based fault tolerant flight control scheme and the interface of the scheme within a simulation/visualization environment. The goal of the fault tolerant flight control scheme is to recover an aircraft from failures to its sensors or actuators. A commercially available simulation package, Aviator Visual Design Simulator (AVDS), was used for the purpose of simulation and visualization of the aircraft dynamics and the performance of the control schemes. For the purpose of the sensor failure detection, identification and accommodation (SFDIA) task, it is assumed that the pitch, roll and yaw rate gyros onboard are without physical redundancy. The task is accomplished through the use of a Main Neural Network (MNN) and a set of three De-Centralized Neural Networks (DNNs), providing analytical redundancy for the pitch, roll and yaw gyros. The purpose of the MNN is to detect a sensor failure while the purpose of the DNNs is to identify the failed sensor and then to provide failure accommodation. The actuator failure detection, identification and accommodation (AFDIA) scheme also features the MNN, for detection of actuator failures, along with three Neural Network Controllers (NNCs) for providing the compensating control surface deflections to neutralize the failure induced pitching, rolling and yawing moments. All NNs continue to train on-line, in addition to an offline trained baseline network structure, using the Extended Back-Propagation Algorithm (EBPA), with the flight data provided by the AVDS simulation package. The above mentioned adaptive flight control schemes have been traditionally implemented sequentially on a single computer. This research addresses the implementation of these fault tolerant flight control schemes on parallel and distributed computer architectures, using Berkeley Software Distribution (BSD) sockets and Message Passing Interface (MPI) for inter

  20. 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.

  1. An improved biometrics-based remote user authentication scheme with user anonymity.

    PubMed

    Khan, Muhammad Khurram; Kumari, Saru

    2013-01-01

    The authors review the biometrics-based user authentication scheme proposed by An in 2012. The authors show that there exist loopholes in the scheme which are detrimental for its security. Therefore the authors propose an improved scheme eradicating the flaws of An's scheme. Then a detailed security analysis of the proposed scheme is presented followed by its efficiency comparison. The proposed scheme not only withstands security problems found in An's scheme but also provides some extra features with mere addition of only two hash operations. The proposed scheme allows user to freely change his password and also provides user anonymity with untraceability.

  2. Breeding programs for smallholder sheep farming systems: I. Evaluation of alternative designs of breeding schemes.

    PubMed

    Gizaw, S; Rischkowsky, B; Valle-Zárate, A; Haile, A; van Arendonk, J A M; Mwai, A O; Dessie, T

    2014-10-01

    Village- and central nucleus-based schemes were simulated and evaluated for their relative bio-economic efficiencies, using Ethiopia's Menz sheep as example. The schemes were: village-based 2-tier (Scheme-1) and 1-tier (Scheme-2) cooperative village breeding schemes, dispersed village-based nuclei scheme (Scheme-3), conventional 2-tier central nucleus-based scheme (Scheme-4), and schemes linking a central nucleus and village multiplier nuclei with selection in central nucleus (Scheme-5) or in both central and village nuclei (Scheme-6). Among village-based schemes, Scheme-1 gave the highest genetic progress, while Scheme-2 was economically the most efficient with genetic gain in the breeding objective of Birr 5.6 and a profit of Birr 37.2/ewe/year. The central nucleus schemes were more efficient than the village schemes. Scheme-4 was the most efficient with genetic gain in the breeding objective of Birr 13.5 and a profit of Birr 71.2, but is operationally more difficult as it requires a very large central nucleus. The choice between village and central nucleus-based schemes would depend on local conditions (availability of infrastructure, logistics and technical knowhow and support). Linking central nucleus with village-based nuclei (Scheme-6) would be a feasible option to overcome the operational difficulties of the conventional central nucleus scheme. If a village-based breeding program is envisaged as should be the 1st step in most low-input systems, then Scheme-2 is the most efficient. To scale out to an entire Menz breed level, Scheme-3 would be recommended.

  3. Sensitivity of land surface and Cumulus schemes for Thunderstorm prediction

    NASA Astrophysics Data System (ADS)

    Kumar, Dinesh; Mohanty, U. C.; Kumar, Krishan

    2016-06-01

    The cloud processes play an important role in all forms of precipitation. Its proper representation is one of the challenging tasks in mesoscale numerical simulation. Studies have revealed that mesoscale feature require proper initialization which may likely to improve the convective system rainfall forecasts. Understanding the precipitation process, model initial condition accuracy and resolved/sub grid-scale precipitation processes representation, are the important areas which needed to improve in order to represent the mesoscale features properly. Various attempts have been done in order to improve the model performance through grid resolution, physical parameterizations, etc. But it is the physical parameterizations which provide a convective atmosphere for the development and intensification of convective events. Further, physical parameterizations consist of cumulus convection, surface fluxes of heat, moisture, momentum, and vertical mixing in the planetary boundary layer (PBL). How PBL and Cumulus schemes capture the evolution of thunderstorm have been analysed by taking thunderstorm cases occurred over Kolkata, India in the year 2011. PBL and cumulus schemes were customized for WSM-6 microphysics because WSM series has been widely used in operational forecast. Results have shown that KF (PBL scheme) and WSM-6 (Cumulus Scheme) have reproduced the evolution of surface variable such as CAPE, temperature and rainfall very much like observation. Further, KF and WSM-6 scheme also provided the increased moisture availability in the lower atmosphere which was taken to higher level by strong vertical velocities providing a platform to initiate a thunderstorm much better. Overestimation of rain in WSM-6 occurs primarily because of occurrence of melting and freezing process within a deeper layer in WSM-6 scheme. These Schemes have reproduced the spatial pattern and peak rainfall coverage closer to TRMM observation. It is the the combination of WSM-6, and KF schemes

  4. The numerical scheme development of a simplified frozen soil model

    NASA Astrophysics Data System (ADS)

    Li, Qian; Sun, Shufen; Dai, Qiudan

    2009-09-01

    In almost all frozen soil models used currently, three variables of temperature, ice content and moisture content are used as prognostic variables and the rate term, accounting for the contribution of the phase change between water and ice, is shown explicitly in both the energy and mass balance equations. The models must be solved by a numerical method with an iterative process, and the rate term of the phase change needs to be pre-estimated at the beginning in each iteration step. Since the rate term of the phase change in the energy equation is closely related to the release or absorption of the great amount of fusion heat, a small error in the rate term estimation will introduce greater error in the energy balance, which will amplify the error in the temperature calculation and in turn, cause problems for the numerical solution convergence. In this work, in order to first reduce the trouble, the methodology of the variable transformation is applied to a simplified frozen soil model used currently, which leads to new frozen soil scheme used in this work. In the new scheme, the enthalpy and the total water equivalent are used as predictive variables in the governing equations to replace temperature, volumetric soil moisture and ice content used in many current models. By doing so, the rate terms of the phase change are not shown explicitly in both the mass and energy equations and its pre-estimation is avoided. Secondly, in order to solve this new scheme more functionally, the development of the numerical scheme to the new scheme is described and a numerical algorithm appropriate to the numerical scheme is developed. In order to evaluate the new scheme of the frozen soil model and its relevant algorithm, a series of model evaluations are conducted by comparing numerical results from the new model scheme with three observational data sets. The comparisons show that the results from the model are in good agreement with these data sets in both the change trend of

  5. An Efficient Hierarchical Video Coding Scheme Combining Visual Perception Characteristics

    PubMed Central

    Liu, Pengyu; Jia, Kebin

    2014-01-01

    Different visual perception characteristic saliencies are the key to constitute the low-complexity video coding framework. A hierarchical video coding scheme based on human visual systems (HVS) is proposed in this paper. The proposed scheme uses a joint video coding framework consisting of visual perception analysis layer (VPAL) and video coding layer (VCL). In VPAL, effective visual perception characteristics detection algorithm is proposed to achieve visual region of interest (VROI) based on the correlation between coding information (such as motion vector, prediction mode, etc.) and visual attention. Then, the interest priority setting for VROI according to visual perception characteristics is completed. In VCL, the optional encoding method is developed utilizing the visual interested priority setting results from VPAL. As a result, the proposed scheme achieves information reuse and complementary between visual perception analysis and video coding. Experimental results show that the proposed hierarchical video coding scheme effectively alleviates the contradiction between complexity and accuracy. Compared with H.264/AVC (JM17.0), the proposed scheme reduces 80% video coding time approximately and maintains a good video image quality as well. It improves video coding performance significantly. PMID:24959623

  6. Compressible bubble dynamic simulations with central-upwind schemes

    NASA Astrophysics Data System (ADS)

    Koukouvinis, P.; Gavaises, M.; Georgoulas, A.; Marengo, M.

    2015-12-01

    This paper discusses the implementation of an explicit density-based solver, based on the central-upwind schemes originally suggested by Kurganov, for the simulation of cavitating bubble dynamic flows. Explicit density based solvers are suited for highly dynamic, violent flows, involving large density ratios, as is rather common in cavitating flows. Moreover, the central-upwind schemes have the advantage of avoiding direct evaluation of the Jacobian matrix or estimation of the wave pattern emerging from Euler equations. Second order accuracy can be achieved with TVD MUSCL schemes. Basic comparison with the predicted wave pattern of the central-upwind schemes is performed with the exact solution of the Riemann problem showing an excellent agreement. Then several different bubble configurations were tested, similar to the work of Lauer et al. (2012). The central-upwind schemes prove to be able to handle the large pressure and density ratios appearing in cavitating flows, giving similar predictions in the evolution of the bubble shape.

  7. Impact of Geoengineering Schemes on the Terrestrial Biosphere

    NASA Astrophysics Data System (ADS)

    Govindasamy, B.; Thompson, S. L.; Duffy, P. B.; Caldeira, K. G.; Delire, C.

    2002-12-01

    Climate stabilization via "Geoengineering" schemes seek to mitigate climate change due to increased greenhouse gases by compensating reduction in solar radiation incident on earth's surface. Though the spatial and temporal pattern of radiative forcing from greenhouse gases differs from that of sunlight, it was shown in recent studies that these schemes would largely mitigate regional or seasonal climate change for a doubling and quadrupling of the atmospheric CO2 content. In this study, we address the impact of these climate stabilization schemes on terrestrial biosphere using equilibrium simulations from a coupled atmosphere-terrestrial biosphere model (CCM3-IBIS). Geoengineering schemes would tend to limit changes in vegetation distribution brought on by climate change, but would not prevent CO2 -induced changes in NPP or biomass; indeed, if CO2 fertilization is significant, then a climate-stabilized world could have higher NPP than our current world. Nevertheless, there are many reasons why geoengineering is not a preferred option for climate stabilization.Impact of Geoengineering Schemes on the Terrestrial Biosphere

  8. An Advanced Leakage Scheme for Neutrino Treatment in Astrophysical Simulations

    NASA Astrophysics Data System (ADS)

    Perego, A.; Cabezón, R. M.; Käppeli, R.

    2016-04-01

    We present an Advanced Spectral Leakage (ASL) scheme to model neutrinos in the context of core-collapse supernovae (CCSNe) and compact binary mergers. Based on previous gray leakage schemes, the ASL scheme computes the neutrino cooling rates by interpolating local production and diffusion rates (relevant in optically thin and thick regimes, respectively) separately for discretized values of the neutrino energy. Neutrino trapped components are also modeled, based on equilibrium and timescale arguments. The better accuracy achieved by the spectral treatment allows a more reliable computation of neutrino heating rates in optically thin conditions. The scheme has been calibrated and tested against Boltzmann transport in the context of Newtonian spherically symmetric models of CCSNe. ASL shows a very good qualitative and a partial quantitative agreement for key quantities from collapse to a few hundreds of milliseconds after core bounce. We have proved the adaptability and flexibility of our ASL scheme, coupling it to an axisymmetric Eulerian and to a three-dimensional smoothed particle hydrodynamics code to simulate core collapse. Therefore, the neutrino treatment presented here is ideal for large parameter-space explorations, parametric studies, high-resolution tests, code developments, and long-term modeling of asymmetric configurations, where more detailed neutrino treatments are not available or are currently computationally too expensive.

  9. Novel discretization schemes for the numerical simulation of membrane dynamics

    NASA Astrophysics Data System (ADS)

    Kolsti, Kyle F.

    Motivated by the demands of simulating flapping wings of Micro Air Vehicles, novel numerical methods were developed and evaluated for the dynamic simulation of membranes. For linear membranes, a mixed-form time-continuous Galerkin method was employed using trilinear space-time elements. Rather than time-marching, the entire space-time domain was discretized and solved simultaneously. Second-order rates of convergence in both space and time were observed in numerical studies. Slight high-frequency noise was filtered during post-processing. For geometrically nonlinear membranes, the model incorporated two new schemes that were independently developed and evaluated. Time marching was performed using quintic Hermite polynomials uniquely determined by end-point jerk constraints. The single-step, implicit scheme was significantly more accurate than the most common Newmark schemes. For a simple harmonic oscillator, the scheme was found to be symplectic, frequency-preserving, and conditionally stable. Time step size was limited by accuracy requirements rather than stability. The spatial discretization scheme employed a staggered grid, grouping of nonlinear terms, and polygon shape functions in a strong-form point collocation formulation. The observed rate of convergence was two for both displacement and strain. Validation against existing experimental data showed the method to be accurate until hyperelastic effects dominate.

  10. Realization of correlation attack against the fuzzy vault scheme

    NASA Astrophysics Data System (ADS)

    Kholmatov, Alisher; Yanikoglu, Berrin

    2008-02-01

    User privacy and template security are major concerns in the use of biometric systems. These are serious concerns based on the fact that once compromised, biometric traits can not be canceled or reissued. The Fuzzy Vault scheme has emerged as a promising method to alleviate the template security problem. The scheme is based on binding the biometric template with a secret key and scrambling it with a large amount of redundant data, such that it is computationally infeasible to extract the secret key without possession of the biometric trait. It was recently claimed that the scheme is susceptible to correlation based attacks which assume the availability of two fuzzy vaults created using the same biometric data (e.g. two impressions of the same fingerprint) and suggests that correlating them would reveal the biometric data hidden inside. In this work, we implemented the fuzzy vault scheme using fingerprints and performed correlation attacks against a database of 400 fuzzy vaults (200 matching pairs). Given two matching vaults, we could successfully unlock 59% of them within a short time. Furthermore, it was possible to link an unknown vault to a short list containing its matching pair, for 41% of all vaults. These results prove the claim that the fuzzy vault scheme without additional security measures is indeed vulnerable to correlation attacks.

  11. A concatenated coded modulation scheme for error control

    NASA Technical Reports Server (NTRS)

    Kasami, Tadao; Takata, Toyoo; Fujiwara, Toru; Lin, Shu

    1990-01-01

    A concatenated coded modulation scheme for error control in data communications is presented. The scheme is achieved by concatenating a Reed-Solomon outer code and a bandwidth efficient block inner code for M-ary PSK modulation. Error performance of the scheme is analyzed for an AWGN channel. It is shown that extremely high reliability can be attained by using a simple M-ary PSK modulation inner code and relatively powerful Reed-Solomon outer code. Furthermore, if an inner code of high effective rate is used, the bandwidth expansion required by the scheme due to coding will be greatly reduced. The proposed scheme is particularly effective for high speed satellite communications for large file transfer where high reliability is required. Also presented is a simple method for constructing block codes for M-ary PSK modulation. Some short M-ary PSK codes with good minimum squared Euclidean distance are constructed. These codes have trellis structure and hence can be decoded with a soft-decision Viterbi decoding algorithm.

  12. Local ensemble assimilation scheme with global constraints and conservation

    NASA Astrophysics Data System (ADS)

    Barth, Alexander; Yan, Yajing; Alvera-Azcárate, Aida; Beckers, Jean-Marie

    2016-12-01

    Ensemble assimilation schemes applied in their original, global formulation respect linear conservation properties if the ensemble perturbations are set up accordingly. For realistic ocean systems, only a relatively small number of ensemble members can be calculated. A localization of the ensemble increment is therefore necessary to filter out spurious long-range correlations. The conservation of the global properties will be lost if the assimilation is performed locally, since the conservation requires a coupling between all model grid points which is removed by the localization. The distribution of ocean observations is often highly inhomogeneous. Systematic errors of the observed parts of the ocean state can lead to spurious adjustment of the non-observed parts via data assimilation and thus to a spurious increase or decrease in long-term simulations of global properties which should be conserved. In this paper, we propose a local assimilation scheme (with different variants and assumptions) which can satisfy global conservation properties. The proposed scheme can also be used for non-local observation operators. Different variants of the proposed scheme are tested in an idealized model and compared to the traditional covariance localization with an ad-hoc step enforcing conservation. It is shown that the inclusion of the conservation property reduces the total RMS error and that the presented stochastic and deterministic schemes avoiding error space rotation provide better results than the traditional covariance localization.

  13. Implicit preconditioned WENO scheme for steady viscous flow computation

    NASA Astrophysics Data System (ADS)

    Huang, Juan-Chen; Lin, Herng; Yang, Jaw-Yen

    2009-02-01

    A class of lower-upper symmetric Gauss-Seidel implicit weighted essentially nonoscillatory (WENO) schemes is developed for solving the preconditioned Navier-Stokes equations of primitive variables with Spalart-Allmaras one-equation turbulence model. The numerical flux of the present preconditioned WENO schemes consists of a first-order part and high-order part. For first-order part, we adopt the preconditioned Roe scheme and for the high-order part, we employ preconditioned WENO methods. For comparison purpose, a preconditioned TVD scheme is also given and tested. A time-derivative preconditioning algorithm is devised and a discriminant is devised for adjusting the preconditioning parameters at low Mach numbers and turning off the preconditioning at intermediate or high Mach numbers. The computations are performed for the two-dimensional lid driven cavity flow, low subsonic viscous flow over S809 airfoil, three-dimensional low speed viscous flow over 6:1 prolate spheroid, transonic flow over ONERA-M6 wing and hypersonic flow over HB-2 model. The solutions of the present algorithms are in good agreement with the experimental data. The application of the preconditioned WENO schemes to viscous flows at all speeds not only enhances the accuracy and robustness of resolving shock and discontinuities for supersonic flows, but also improves the accuracy of low Mach number flow with complicated smooth solution structures.

  14. AN ADVANCED LEAKAGE SCHEME FOR NEUTRINO TREATMENT IN ASTROPHYSICAL SIMULATIONS

    SciTech Connect

    Perego, A.; Cabezón, R. M.; Käppeli, R.

    2016-04-15

    We present an Advanced Spectral Leakage (ASL) scheme to model neutrinos in the context of core-collapse supernovae (CCSNe) and compact binary mergers. Based on previous gray leakage schemes, the ASL scheme computes the neutrino cooling rates by interpolating local production and diffusion rates (relevant in optically thin and thick regimes, respectively) separately for discretized values of the neutrino energy. Neutrino trapped components are also modeled, based on equilibrium and timescale arguments. The better accuracy achieved by the spectral treatment allows a more reliable computation of neutrino heating rates in optically thin conditions. The scheme has been calibrated and tested against Boltzmann transport in the context of Newtonian spherically symmetric models of CCSNe. ASL shows a very good qualitative and a partial quantitative agreement for key quantities from collapse to a few hundreds of milliseconds after core bounce. We have proved the adaptability and flexibility of our ASL scheme, coupling it to an axisymmetric Eulerian and to a three-dimensional smoothed particle hydrodynamics code to simulate core collapse. Therefore, the neutrino treatment presented here is ideal for large parameter-space explorations, parametric studies, high-resolution tests, code developments, and long-term modeling of asymmetric configurations, where more detailed neutrino treatments are not available or are currently computationally too expensive.

  15. Reactivity Control Schemes for Fast Spectrum Space Nuclear Reactors

    SciTech Connect

    Craft, Aaron E.; King, Jeffrey C.

    2008-01-21

    Several different reactivity control schemes are considered for future space nuclear reactor power systems. Each of these control schemes uses a combination of boron carbide absorbers and/or beryllium oxide reflectors to achieve sufficient reactivity swing to keep the reactor subcritical during launch and to provide sufficient excess reactivity to operate the reactor over its expected 7-15 year lifetime. The size and shape of the control system directly impacts the size and mass of the space reactor's reflector and shadow shield, leading to a tradeoff between reactivity swing and total system mass. This paper presents a trade study of drum, shutter, and petal control schemes based on reactivity swing and mass effects for a representative fast-spectrum, gas-cooled reactor. For each control scheme, the dimensions and composition of the core are constant, and the reflector is sized to provide $5 of cold-clean excess reactivity with each configuration in its most reactive state. The advantages and disadvantages of each configuration are discussed, along with optimization techniques and novel geometric approaches for each scheme.

  16. Market behavior and performance of different strategy evaluation schemes

    NASA Astrophysics Data System (ADS)

    Baek, Yongjoo; Lee, Sang Hoon; Jeong, Hawoong

    2010-08-01

    Strategy evaluation schemes are a crucial factor in any agent-based market model, as they determine the agents’ strategy preferences and consequently their behavioral pattern. This study investigates how the strategy evaluation schemes adopted by agents affect their performance in conjunction with the market circumstances. We observe the performance of three strategy evaluation schemes, the history-dependent wealth game, the trend-opposing minority game, and the trend-following majority game, in a stock market where the price is exogenously determined. The price is either directly adopted from the real stock market indices or generated with a Markov chain of order ≤2 . Each scheme’s success is quantified by average wealth accumulated by the traders equipped with the scheme. The wealth game, as it learns from the history, shows relatively good performance unless the market is highly unpredictable. The majority game is successful in a trendy market dominated by long periods of sustained price increase or decrease. On the other hand, the minority game is suitable for a market with persistent zigzag price patterns. We also discuss the consequence of implementing finite memory in the scoring processes of strategies. Our findings suggest under which market circumstances each evaluation scheme is appropriate for modeling the behavior of real market traders.

  17. An improved auto-tuning scheme for PID controllers.

    PubMed

    Dey, Chanchal; Mudi, Rajani K

    2009-10-01

    An improved auto-tuning scheme is proposed for Ziegler-Nichols (ZN) tuned PID controllers (ZNPIDs), which usually provide excessively large overshoots, not tolerable in most of the situations, for high-order and nonlinear processes. To overcome this limitation ZNPIDs are upgraded by some easily interpretable heuristic rules through an online gain modifying factor defined on the instantaneous process states. This study is an extension of our earlier work [Mudi RK., Dey C. Lee TT. An improved auto-tuning scheme for PI controllers. ISA Trans 2008; 47: 45-52] to ZNPIDs, thereby making the scheme suitable for a wide range of processes and more generalized too. The proposed augmented ZNPID (AZNPID) is tested on various high-order linear and nonlinear dead-time processes with improved performance over ZNPID, refined ZNPID (RZNPID), and other schemes reported in the literature. Stability issues are addressed for linear processes. Robust performance of AZNPID is observed while changing its tunable parameters as well as the process dead-time. The proposed scheme is also implemented on a real time servo-based position control system.

  18. Evaluation of copyright protection schemes for hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Minguillon, Julia; Herrera-Joancomarti, Jordi; Megias, David; Serra-Sagrista, Joan

    2004-02-01

    In this paper we evaluate the performance of several image watermarking schemes applied to hyperspectral imaging. An image watermarking scheme based on JPEG2000 which can be also used to store and manipulate hyperspectral images is also described. Different watermarking schemes are tested in order to determine the suitability of each one for a specific hyperspectral image environment. The impact of classical GIS operations (namely zooming, cropping and compression) on the performance of each watermarking scheme is measured in terms of capacity and robustness. In order to do so, we study several possibilities for watermarking hyperspectral images, as all hyperspectral image bands should be taken into account. We also study the impact of watermarking in image quality, measured as usual by PSNR, but also by the degradation of classification performance. Compression, classification and watermarking are closely related to each other as decisions taken in one subject have a large impact on the others. Our results show that the newcomer JPEG2000 standard is a useful tool for both hyperspectral imaging and copyright protection purposes. The proposed watermarking scheme, which takes advantage of JPEG2000 standard capabilities, can be considered to be robust under the constraints defined by the integration of hyperspectral imaging with geographical information systems. JPEG2000 extensions defined by the standard related to this work are also considered.

  19. An Orbit And Dispersion Correction Scheme for the PEP II

    SciTech Connect

    Cai, Y.; Donald, M.; Shoaee, H.; White, G.; Yasukawa, L.A.; /SLAC

    2011-09-01

    To achieve optimum luminosity in a storage ring it is vital to control the residual vertical dispersion. In the original PEP storage ring, a scheme to control the residual dispersion function was implemented using the ring orbit as the controlling element. The 'best' orbit not necessarily giving the lowest vertical dispersion. A similar scheme has been implemented in both the on-line control code and in the simulation code LEGO. The method involves finding the response matrices (sensitivity of orbit/dispersion at each Beam-Position-Monitor (BPM) to each orbit corrector) and solving in a least squares sense for minimum orbit, dispersion function or both. The optimum solution is usually a subset of the full least squares solution. A scheme of simultaneously correcting the orbits and dispersion has been implemented in the simulation code and on-line control system for PEP-II. The scheme is based on the eigenvector decomposition method. An important ingredient of the scheme is to choose the optimum eigenvectors that minimize the orbit, dispersion and corrector strength. Simulations indicate this to be a very effective way to control the vertical residual dispersion.

  20. New, Improved Bulk-microphysical Schemes for Studying Precipitation Processes in WRF. Part 1; Comparisons with Other Schemes

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Shi, J.; Chen, S. S> ; Lang, S.; Hong, S.-Y.; Thompson, G.; Peters-Lidard, C.; Hou, A.; Braun, S.; Simpson, J.

    2007-01-01

    Advances in computing power allow atmospheric prediction models to be mn at progressively finer scales of resolution, using increasingly more sophisticated physical parameterizations and numerical methods. The representation of cloud microphysical processes is a key component of these models, over the past decade both research and operational numerical weather prediction models have started using more complex microphysical schemes that were originally developed for high-resolution cloud-resolving models (CRMs). A recent report to the United States Weather Research Program (USWRP) Science Steering Committee specifically calls for the replacement of implicit cumulus parameterization schemes with explicit bulk schemes in numerical weather prediction (NWP) as part of a community effort to improve quantitative precipitation forecasts (QPF). An improved Goddard bulk microphysical parameterization is implemented into a state-of the-art of next generation of Weather Research and Forecasting (WRF) model. High-resolution model simulations are conducted to examine the impact of microphysical schemes on two different weather events (a midlatitude linear convective system and an Atllan"ic hurricane). The results suggest that microphysics has a major impact on the organization and precipitation processes associated with a summer midlatitude convective line system. The 31CE scheme with a cloud ice-snow-hail configuration led to a better agreement with observation in terms of simulated narrow convective line and rainfall intensity. This is because the 3ICE-hail scheme includes dense ice precipitating (hail) particle with very fast fall speed (over 10 m/s). For an Atlantic hurricane case, varying the microphysical schemes had no significant impact on the track forecast but did affect the intensity (important for air-sea interaction)

  1. Customer oriented SNR scalability scheme for scalable video coding

    NASA Astrophysics Data System (ADS)

    Li, Z. G.; Rahardja, S.

    2005-07-01

    Let the whole region be the whole bit rate range that customers are interested in, and a sub-region be a specific bit rate range. The weighting factor of each sub-region is determined according to customers' interest. A new type of region of interest (ROI) is defined for the SNR scalability as the gap between the coding efficiency of SNR scalability scheme and that of the state-of-the-art single layer coding for a sub-region is a monotonically non-increasing function of its weighting factor. This type of ROI is used as a performance index to design a customer oriented SNR scalability scheme. Our scheme can be used to achieve an optimal customer oriented scalable tradeoff (COST). The profit can thus be maximized.

  2. An Improved Lattice Kinetic Scheme for Incompressible Viscous Fluid Flows

    NASA Astrophysics Data System (ADS)

    Suzuki, Kosuke; Inamuro, Takaji

    2014-01-01

    The lattice Boltzmann method (LBM) is an explicit numerical scheme for the incompressible Navier-Stokes equations (INSE) without integrating the Poisson equation for the pressure. In spite of its merit, the LBM has some drawbacks in accuracy. First, we review drawbacks for three numerical methods based on the LBM. The three methods are the LBM with the Bhatnagar-Gross-Krook model (LBGK), the lattice kinetic scheme (LKS) and the link-wise artificial compressibility method (LWACM). Second, in order to remedy the drawbacks, we propose an improved LKS. The present method incorporates (i) the scheme used in the LWACM for determining the kinematic viscosity, (ii) an iterative calculation of the pressure and (iii) a semi-implicit algorithm, while preserving the simplicity of the algorithm of the original LKS. Finally, in simulations of test problems, we find that the improved LKS eliminates the drawbacks and gives more accurate and stable results than LBGK, LKS and LWACM.

  3. A privacy authentication scheme based on cloud for medical environment.

    PubMed

    Chen, Chin-Ling; Yang, Tsai-Tung; Chiang, Mao-Lun; Shih, Tzay-Farn

    2014-11-01

    With the rapid development of the information technology, the health care technologies already became matured. Such as electronic medical records that can be easily stored. However, how to get medical resources more convenient is currently concerning issue. In spite of many literatures discussed about medical systems, these literatures should face many security challenges. The most important issue is patients' privacy. Therefore, we propose a privacy authentication scheme based on cloud environment. In our scheme, we use mobile device's characteristics, allowing peoples to use medical resources on the cloud environment to find medical advice conveniently. The digital signature is used to ensure the security of the medical information that is certified by the medical department in our proposed scheme.

  4. A Cell-Centered Multiphase ALE Scheme With Structural Coupling

    SciTech Connect

    Dunn, Timothy Alan

    2012-04-16

    A novel computational scheme has been developed for simulating compressible multiphase flows interacting with solid structures. The multiphase fluid is computed using a Godunov-type finite-volume method. This has been extended to allow computations on moving meshes using a direct arbitrary-Eulerian- Lagrangian (ALE) scheme. The method has been implemented within a Lagrangian hydrocode, which allows modeling the interaction with Lagrangian structural regions. Although the above scheme is general enough for use on many applications, the ultimate goal of the research is the simulation of heterogeneous energetic material, such as explosives or propellants. The method is powerful enough for application to all stages of the problem, including the initial burning of the material, the propagation of blast waves, and interaction with surrounding structures. The method has been tested on a number of canonical multiphase tests as well as fluid-structure interaction problems.

  5. A Scheme for Compressing Floating-Point Images

    NASA Astrophysics Data System (ADS)

    White, Richard L.; Greenfield, Perry

    While many techniques have been used to compress integer data, compressing floating-point data presents a number of additional problems. We have implemented a scheme for compressing floating-point images that is fast, robust, and automatic, that allows random access to pixels without decompressing the whole image, and that generally has a scientifically negligible effect on the noise present in the image. The compressed data are stored in an FITS binary table. Most astronomical images can be compressed by approximately a factor of 3, using conservative settings for the permitted level of changes in the data. We intend to work with NOAO to incorporate this compression method into the IRAF image kernel, so that FITS images compressed using this scheme can be accessed transparently from IRAF applications without any explicit decompression steps. The scheme is simple, and it should be possible to include it in other FITS libraries as well.

  6. Adaptive PCA based fault diagnosis scheme in imperial smelting process.

    PubMed

    Hu, Zhikun; Chen, Zhiwen; Gui, Weihua; Jiang, Bin

    2014-09-01

    In this paper, an adaptive fault detection scheme based on a recursive principal component analysis (PCA) is proposed to deal with the problem of false alarm due to normal process changes in real process. Our further study is also dedicated to develop a fault isolation approach based on Generalized Likelihood Ratio (GLR) test and Singular Value Decomposition (SVD) which is one of general techniques of PCA, on which the off-set and scaling fault can be easily isolated with explicit off-set fault direction and scaling fault classification. The identification of off-set and scaling fault is also applied. The complete scheme of PCA-based fault diagnosis procedure is proposed. The proposed scheme is first applied to Imperial Smelting Process, and the results show that the proposed strategies can be able to mitigate false alarms and isolate faults efficiently.

  7. Efficient Scheme for Perfect Collective Einstein-Podolsky-Rosen Steering

    PubMed Central

    Wang, M.; Gong, Q. H.; Ficek, Z.; He, Q. Y.

    2015-01-01

    A practical scheme for the demonstration of perfect one-sided device-independent quantum secret sharing is proposed. The scheme involves a three-mode optomechanical system in which a pair of independent cavity modes is driven by short laser pulses and interact with a movable mirror. We demonstrate that by tuning the laser frequency to the blue (anti-Stokes) sideband of the average frequency of the cavity modes, the modes become mutually coherent and then may collectively steer the mirror mode to a perfect Einstein-Podolsky-Rosen state. The scheme is shown to be experimentally feasible, it is robust against the frequency difference between the modes, mechanical thermal noise and damping, and coupling strengths of the cavity modes to the mirror. PMID:26212901

  8. Development of upwind schemes for the Euler equations

    NASA Technical Reports Server (NTRS)

    Chakravarthy, Sukumar R.

    1987-01-01

    Described are many algorithmic and computational aspects of upwind schemes and their second-order accurate formulations based on Total-Variation-Diminishing (TVD) approaches. An operational unification of the underlying first-order scheme is first presented encompassing Godunov's, Roe's, Osher's, and Split-Flux methods. For higher order versions, the preprocessing and postprocessing approaches to constructing TVD discretizations are considered. TVD formulations can be used to construct relaxation methods for unfactored implicit upwind schemes, which in turn can be exploited to construct space-marching procedures for even the unsteady Euler equations. A major part of the report describes time- and space-marching procedures for solving the Euler equations in 2-D, 3-D, Cartesian, and curvilinear coordinates. Along with many illustrative examples, several results of efficient computations on 3-D supersonic flows with subsonic pockets are presented.

  9. The nonlinear modified equation approach to analyzing finite difference schemes

    NASA Technical Reports Server (NTRS)

    Klopfer, G. H.; Mcrae, D. S.

    1981-01-01

    The nonlinear modified equation approach is taken in this paper to analyze the generalized Lax-Wendroff explicit scheme approximation to the unsteady one- and two-dimensional equations of gas dynamics. Three important applications of the method are demonstrated. The nonlinear modified equation analysis is used to (1) generate higher order accurate schemes, (2) obtain more accurate estimates of the discretization error for nonlinear systems of partial differential equations, and (3) generate an adaptive mesh procedure for the unsteady gas dynamic equations. Results are obtained for all three areas. For the adaptive mesh procedure, mesh point requirements for equal resolution of discontinuities were reduced by a factor of five for a 1-D shock tube problem solved by the explicit MacCormack scheme.

  10. Evolution of the Z-scheme of photosynthesis: a perspective.

    PubMed

    Govindjee; Shevela, Dmitriy; Björn, Lars Olof

    2017-02-03

    The concept of the Z-scheme of oxygenic photosynthesis is in all the textbooks. However, its evolution is not. We focus here mainly on some of the history of its biophysical aspects. We have arbitrarily divided here the 1941-2016 period into three sub-periods: (a) Origin of the concept of two light reactions: first hinted at, in 1941, by James Franck and Karl Herzfeld; described and explained, in 1945, by Eugene Rabinowitch; and a clear hypothesis, given in 1956 by Rabinowitch, of the then available cytochrome experiments: one light oxidizing it and another reducing it; (b) Experimental discovery of the two light reactions and two pigment systems and the Z-scheme of photosynthesis: Robert Emerson's discovery, in 1957, of enhancement in photosynthesis when two light beams (one in the far-red region, and the other of shorter wavelengths) are given together than when given separately; and the 1960 scheme of Robin Hill & Fay Bendall; and

  11. Analysis of Control Power in Controlled Remote State Preparation Schemes

    NASA Astrophysics Data System (ADS)

    Li, Xihan; Ghose, Shohini

    2017-03-01

    We quantify and analyze the controller's power in controlled remote state preparation schemes. Our analysis provides a lower bound on the control power required for controlled remote preparation of arbitrary D-dimensional states. We evaluate several existing controlled remote state preparation protocols and show that some proposed non-maximally entangled channels are not suitable for perfect controlled remote preparation of arbitrary quantum states from the controller's point of view. We find that for remotely preparing D-dimensional states, the entropy of each controller should be no less than log2 D bits. Our new criteria are not only useful for evaluating controlled remote state preparation schemes but can also be used for other controlled quantum communication schemes.

  12. A New Harmonic Mitigation Scheme for MMC - An Experimental Approach

    NASA Astrophysics Data System (ADS)

    Madichetty, S.; Dasgupta, A.; Jinka, S.

    2014-06-01

    A multilevel converter has been brought into limelight in this article, however, particular attention has been provided to the form and function of modular multilevel converter (MMC) with new design, control and harmonic mitigation schemes. A new controller scheme has been proposed to mitigate the lower and higher order harmonics. The proposed scheme shows its effectiveness by theoretical calculations, verified by simulation and experimental results. Till date, research in this field is very limited with circulating currents and harmonics as the major problem. This article effectively addresses the problem with prototype 1 kVA implementation and attempts to make a detailed analysis with their functions in comprehensive manner with high-voltage DC application under different conditions. Also, the applicability of zero voltage switching at turn ON and zero current transition at turn OFF has been verified experimentally. The strategic conclusions on MMC have been made in order to make the system more robust in operation, less complexity in design and control.

  13. Edge-based finite element scheme for the Euler equations

    NASA Astrophysics Data System (ADS)

    Luo, Hong; Baum, Joseph D.; Loehner, Rainald

    1994-06-01

    This paper describes the development, validation, and application of a new finite element scheme for the solution of the compressible Euler equations on unstructured grids. The implementation of the numerical scheme is based on an edge-based data structure, as opposed to a more element-based data structure. The use of this edge-based data structure not only improves the efficiency of the algorithm but also enables a straightforward implementation of the upwind schemes in the context of finite element methods. The algorithm has been tested and validated on some well documented configurations. A flow solution about a complete F-18 fighter is shown to demonstrate the accuracy and robustness of the proposed algorithm.

  14. Edge-based finite element scheme for the Euler equations

    NASA Astrophysics Data System (ADS)

    Luo, Hong; Baum, Joseph D.; Lohner, Rainald

    1994-06-01

    This paper describes the development, validation, and application of a new finite element scheme for the solution of the compressible Euler equations on unstructured grids. The implementation of the numerical scheme is based on an edge-based data structure, as opposed to a more traditional element-based data structure. The use of this edge-based data structure not only improves the efficiency of the algorithm but also enables a straightforward implementation of upwind schemes in the context of finite element methods. The algorithm has been tested and validated on some well-documented configurations. A flow solution about a complete F-18 fighter is shown to demonstrate the accuracy and robustness of the proposed algorithm.

  15. Secure SCADA communication by using a modified key management scheme.

    PubMed

    Rezai, Abdalhossein; Keshavarzi, Parviz; Moravej, Zahra

    2013-07-01

    This paper presents and evaluates a new cryptographic key management scheme which increases the efficiency and security of the Supervisory Control And Data Acquisition (SCADA) communication. In the proposed key management scheme, two key update phases are used: session key update and master key update. In the session key update phase, session keys are generated in the master station. In the master key update phase, the Elliptic Curve Diffie-Hellman (ECDH) protocol is used. The Poisson process is also used to model the Security Index (SI) and Quality of Service (QoS). Our analysis shows that the proposed key management not only supports the required speed in the MODBUS implementation but also has several advantages compared to other key management schemes for secure communication in SCADA networks.

  16. Quantum blind dual-signature scheme without arbitrator

    NASA Astrophysics Data System (ADS)

    Li, Wei; Shi, Ronghua; Huang, Dazu; Shi, Jinjing; Guo, Ying

    2016-03-01

    Motivated by the elegant features of a bind signature, we suggest the design of a quantum blind dual-signature scheme with three phases, i.e., initial phase, signing phase and verification phase. Different from conventional schemes, legal messages are signed not only by the blind signatory but also by the sender in the signing phase. It does not rely much on an arbitrator in the verification phase as the previous quantum signature schemes usually do. The security is guaranteed by entanglement in quantum information processing. Security analysis demonstrates that the signature can be neither forged nor disavowed by illegal participants or attacker. It provides a potential application for e-commerce or e-payment systems with the current technology.

  17. Downselect of the signal extraction scheme for LCGT

    NASA Astrophysics Data System (ADS)

    Kokeyama, K.; Sato, S.; Kawazoe, F.; Somiya, K.; Fukushima, M.; Kawamura, S.; Sugamoto, Akio

    2006-03-01

    Large Cryogenic Gravitational wave Telescope (LCGT) is the future Japanese gravitational-wave detector. It will employ the broadband resonant sideband extraction (RSE) as its optical configuration. We compared four signal extraction schemes that have been proposed so as to downselect one of them as the scheme for LCGT. The selected scheme uses the phase and amplitude modulation sidebands: the phase modulation sidebands transmitting to the antisymmetric port (AP) and the amplitude modulation sidebands reffected to the symmetric port (SP) by the functions of the Michelson asymmetry. Using these sidebands, a new technique called 'delocation' is applicable. One advantage is that the control signals of the undesired signals do not appear at the AP, where the differential signals appear.

  18. Quantum secure direct communication with frequency coding scheme

    NASA Astrophysics Data System (ADS)

    Zhao, Xue-Liang; Ruan, Dong

    2016-11-01

    Quantum secure direct communication (QSDC) is an important branch of quantum cryptography. It can transmit secret information directly without establishing a key first, unlike quantum key distribution which requires this precursive event. One of the most highlighted QSDC protocol is the Two-step protocol. This paper will focus on proposing a frequency coding scheme in the Two-step protocol, while retaining other contents of the QSDC protocol. This new coding scheme will significantly increase the protocol's ability against channel noise and loss, and provides an efficient protocol for secure direct quantum communication in a noisy environment. Besides, the frequency coding technology is also easy to understand and highly practical. After numerically simulating the performance of the protocol in a noisy channel, the results showed that the scheme was robust against channel noise and loss.

  19. A Technique of Treating Negative Weights in WENO Schemes

    NASA Technical Reports Server (NTRS)

    Shi, Jing; Hu, Changqing; Shu, Chi-Wang

    2000-01-01

    High order accurate weighted essentially non-oscillatory (WENO) schemes have recently been developed for finite difference and finite volume methods both in structural and in unstructured meshes. A key idea in WENO scheme is a linear combination of lower order fluxes or reconstructions to obtain a high order approximation. The combination coefficients, also called linear weights, are determined by local geometry of the mesh and order of accuracy and may become negative. WENO procedures cannot be applied directly to obtain a stable scheme if negative linear weights are present. Previous strategy for handling this difficulty is by either regrouping of stencils or reducing the order of accuracy to get rid of the negative linear weights. In this paper we present a simple and effective technique for handling negative linear weights without a need to get rid of them.

  20. Realization schemes for quantum instruments in finite dimensions

    SciTech Connect

    Chiribella, Giulio; Perinotti, Paolo; D'Ariano, Giacomo Mauro

    2009-04-15

    We present a general dilation scheme for quantum instruments with continuous outcome space in finite dimensions, in terms of a measurement on a finite-dimensional ancilla, described by a positive operator valued measure (POVM). The general result is then applied to a large class of instruments generated by operator frames, which contains group-covariant instruments as a particular case and allows one to construct dilation schemes based on a measurement on the ancilla followed by a conditional feed-forward operation on the output. In the case of tight operator frames, our construction generalizes quantum teleportation and telecloning, producing a whole family of generalized teleportation schemes in which the instrument is realized via a joint POVM at the sender combined with a conditional feed-forward operation at the receiver.

  1. Simulation of obstacle detection scheme for Mars terrain using minicomputer

    NASA Technical Reports Server (NTRS)

    Leung, K. L.; Shen, C. N.

    1976-01-01

    Simulation for detection of obstacles on Martian terrain by a laser rangefinder mounted on an autonomous roving vehicle is achieved by a rapid estimation scheme on a computer with IDIIOM display. Near and far edges of pyramids and hemispherical craters or boulders can be recognized if the obstacles are more than about 15 m from the laser rangefinder and the noise standard deviation is less than about 10 cm. If these conditions are not met the rapid estimation scheme can still detect the top edge of a boulder and the near edge of a crater. The scheme is considered equivalent or better than an earlier (Reed, Sanyal, and Shen, 1974) four-directional Laplacian method, but requires slightly more computation.

  2. Proposal of Wireless Traffic Control Schemes for Wireless LANs

    NASA Astrophysics Data System (ADS)

    Hiraguri, Takefumi; Ichikawa, Takeo; Iizuka, Masataka; Kubota, Shuji

    This paper proposes two traffic control schemes to support the communication quality of multimedia streaming services such as VoIP and audio/video over IEEE 802.11 wireless LAN systems. The main features of the proposed scheme are bandwidth control for each flow of the multimedia streaming service and load balancing between access points (APs) of the wireless LAN by using information of data link, network and transport layers. The proposed schemes are implemented on a Linux machine which is called the wireless traffic controller (WTC). The WTC connects a high capacity backbone network and an access network to which the APs are attached. We evaluated the performance of the proposed WTC and confirmed that the communication quality of the multimedia streaming would be greatly improved by using this technique.

  3. Uniformly high order accurate essentially non-oscillatory schemes 3

    NASA Technical Reports Server (NTRS)

    Harten, A.; Engquist, B.; Osher, S.; Chakravarthy, S. R.

    1986-01-01

    In this paper (a third in a series) the construction and the analysis of essentially non-oscillatory shock capturing methods for the approximation of hyperbolic conservation laws are presented. Also presented is a hierarchy of high order accurate schemes which generalizes Godunov's scheme and its second order accurate MUSCL extension to arbitrary order of accuracy. The design involves an essentially non-oscillatory piecewise polynomial reconstruction of the solution from its cell averages, time evolution through an approximate solution of the resulting initial value problem, and averaging of this approximate solution over each cell. The reconstruction algorithm is derived from a new interpolation technique that when applied to piecewise smooth data gives high-order accuracy whenever the function is smooth but avoids a Gibbs phenomenon at discontinuities. Unlike standard finite difference methods this procedure uses an adaptive stencil of grid points and consequently the resulting schemes are highly nonlinear.

  4. Averaging schemes for solving fixed point and variational inequality problems

    SciTech Connect

    Magnanti, T.L.; Perakis, G.

    1994-12-31

    In this talk we develop and study averaging schemes for solving fixed point and variational inequality problems. Typically, researchers have established convergence results for methods that solve these problems by establishing contractive estimates for the underlying algorithmic maps. In this talk we establish global convergence results using nonexpansive estimates. After first establishing convergence for a general iterative scheme for computing fixed points, we consider applications to projection and relaxation algorithms for solving variational inequality problems and to a generalized steepest descent method for solving systems of equations. As part of our development, we also establish a new interpretation of a norm condition typically used for establishing convergence of linearization schemes, by associating it with a strong-f-monotonicity condition. We conclude by applying these results to congested transportation networks.

  5. A novel robust speed controller scheme for PMBLDC motor.

    PubMed

    Thirusakthimurugan, P; Dananjayan, P

    2007-10-01

    The design of speed and position controllers for permanent magnet brushless DC motor (PMBLDC) drive remains as an open problem in the field of motor drives. A precise speed control of PMBLDC motor is complex due to nonlinear coupling between winding currents and rotor speed. In addition, the nonlinearity present in the developed torque due to magnetic saturation of the rotor further complicates this issue. This paper presents a novel control scheme to the conventional PMBLDC motor drive, which aims at improving the robustness by complete decoupling of the design besides minimizing the mutual influence among the speed and current control loops. The interesting feature of this robust control scheme is its suitability for both static and dynamic aspects. The effectiveness of the proposed robust speed control scheme is verified through simulations.

  6. Near-unit-fidelity entanglement distribution scheme using Gaussian communication

    SciTech Connect

    Praxmeyer, Ludmila; Loock, Peter van

    2010-06-15

    We show how to distribute with percentage success probabilities almost perfectly entangled qubit memory pairs over repeater channel segments of the order of the optical attenuation distance. In addition to some weak, dispersive light-matter interactions, only Gaussian state transmissions and measurements are needed for this scheme. Our protocol outperforms the existing coherent-state-based schemes for entanglement distribution, even those using error-free non-Gaussian measurements. This is achieved through two innovations: First, optical squeezed states are utilized instead of coherent states. Second, the amplitudes of the bright signal pulses are reamplified at each repeater station. This latter variation is a strategy reminiscent of classical repeaters and would be impossible in single-photon-based schemes.

  7. Suboptimal greedy power allocation schemes for discrete bit loading.

    PubMed

    Al-Hanafy, Waleed; Weiss, Stephan

    2013-01-01

    We consider low cost discrete bit loading based on greedy power allocation (GPA) under the constraints of total transmit power budget, target BER, and maximum permissible QAM modulation order. Compared to the standard GPA, which is optimal in terms of maximising the data throughput, three suboptimal schemes are proposed, which perform GPA on subsets of subchannels only. These subsets are created by considering the minimum SNR boundaries of QAM levels for a given target BER. We demonstrate how these schemes can significantly reduce the computational complexity required for power allocation, particularly in the case of a large number of subchannels. Two of the proposed algorithms can achieve near optimal performance including a transfer of residual power between subsets at the expense of a very small extra cost. By simulations, we show that the two near optimal schemes, while greatly reducing complexity, perform best in two separate and distinct SNR regions.

  8. Suboptimal Greedy Power Allocation Schemes for Discrete Bit Loading

    PubMed Central

    2013-01-01

    We consider low cost discrete bit loading based on greedy power allocation (GPA) under the constraints of total transmit power budget, target BER, and maximum permissible QAM modulation order. Compared to the standard GPA, which is optimal in terms of maximising the data throughput, three suboptimal schemes are proposed, which perform GPA on subsets of subchannels only. These subsets are created by considering the minimum SNR boundaries of QAM levels for a given target BER. We demonstrate how these schemes can significantly reduce the computational complexity required for power allocation, particularly in the case of a large number of subchannels. Two of the proposed algorithms can achieve near optimal performance including a transfer of residual power between subsets at the expense of a very small extra cost. By simulations, we show that the two near optimal schemes, while greatly reducing complexity, perform best in two separate and distinct SNR regions. PMID:24501578

  9. New optical scheme for a polarimetric-based glucose sensor

    NASA Technical Reports Server (NTRS)

    Ansari, Rafat R.; Bockle, Stefan; Rovati, Luigi

    2004-01-01

    A new optical scheme to detect glucose concentration in the aqueous humor of the eye is presented. The ultimate aim is to apply this technique in designing a new instrument for, routinely and frequently, noninvasively monitoring blood glucose levels in diabetic patients without contact (no index matching) between the eye and the instrument. The optical scheme exploits the Brewster reflection of circularly polarized light off of the lens of the eye. Theoretically, this reflected linearly polarized light on its way to the detector is expected to rotate its state of polarization, owing to the presence of glucose molecules in the aqueous humor of a patient's eye. An experimental laboratory setup based on this scheme was designed and tested by measuring a range of known concentrations of glucose solutions dissolved in water. (c) 2004 Society of Photo-Optical Instrumentation Engineers.

  10. Scheme for fault-tolerant holonomic computation on stabilizer codes

    NASA Astrophysics Data System (ADS)

    Oreshkov, Ognyan; Brun, Todd A.; Lidar, Daniel A.

    2009-08-01

    This paper generalizes and expands upon the work [O. Oreshkov, T. A. Brun, and D. A. Lidar, Phys. Rev. Lett. 102, 070502 (2009)] where we introduced a scheme for fault-tolerant holonomic quantum computation (HQC) on stabilizer codes. HQC is an all-geometric strategy based on non-Abelian adiabatic holonomies, which is known to be robust against various types of errors in the control parameters. The scheme we present shows that HQC is a scalable method of computation and opens the possibility for combining the benefits of error correction with the inherent resilience of the holonomic approach. We show that with the Bacon-Shor code the scheme can be implemented using Hamiltonian operators of weights 2 and 3.

  11. Ka-band geostationary satellite spacing requirements and access schemes

    NASA Technical Reports Server (NTRS)

    Caron, Mario; Hindson, Daniel J.

    1995-01-01

    Geostationary satellite systems for wideband personal communications applications have been proposed. This paper looks at the geostationary satellite spacing requirement to meet the ITU-R sharing criterion for FDMA and CDMA access schemes. CDMA capacity equation is first developed. Then the basis for the interference analysis between two systems with an overlapping coverage area is developed for the cases of identical and different access schemes and for bandwidth and power limited systems. An example of an interference analysis between two systems is fully carried out. The paper also points out the inherent problems when comparing systems with different access schemes. It is found that under certain scenarios, CDMA can allow a closer spacing between satellites.

  12. An ICA based MIMO-OFDM VLC scheme

    NASA Astrophysics Data System (ADS)

    Jiang, Fangqing; Deng, Honggui; Xiao, Wei; Tao, Shaohua; Zhu, Kaicheng

    2015-07-01

    In this paper, we propose a novel ICA based MIMO-OFDM VLC scheme, where ICA is applied to convert the MIMO-OFDM channel into several SISO-OFDM channels to reduce computational complexity in channel estimation, without any spectral overhead. Besides, the FM is first investigated to further modulate the OFDM symbols to eliminate the correlation of the signals, so as to improve the separation performance of the ICA algorithm. In the 4×4MIMO-OFDM VLC simulation experiment, LOS path and NLOS paths are both considered, each transmitting signal at 100 Mb/s. Simulation results show that the BER of the proposed scheme reaches the 10-5 level at SNR=20 dB, which is a large improvement compared to the traditional schemes.

  13. An adaptive control scheme for a flexible manipulator

    NASA Technical Reports Server (NTRS)

    Yang, T. C.; Yang, J. C. S.; Kudva, P.

    1987-01-01

    The problem of controlling a single link flexible manipulator is considered. A self-tuning adaptive control scheme is proposed which consists of a least squares on-line parameter identification of an equivalent linear model followed by a tuning of the gains of a pole placement controller using the parameter estimates. Since the initial parameter values for this model are assumed unknown, the use of arbitrarily chosen initial parameter estimates in the adaptive controller would result in undesirable transient effects. Hence, the initial stage control is carried out with a PID controller. Once the identified parameters have converged, control is transferred to the adaptive controller. Naturally, the relevant issues in this scheme are tests for parameter convergence and minimization of overshoots during control switch-over. To demonstrate the effectiveness of the proposed scheme, simulation results are presented with an analytical nonlinear dynamic model of a single link flexible manipulator.

  14. Efficient Scheme for Perfect Collective Einstein-Podolsky-Rosen Steering.

    PubMed

    Wang, M; Gong, Q H; Ficek, Z; He, Q Y

    2015-07-27

    A practical scheme for the demonstration of perfect one-sided device-independent quantum secret sharing is proposed. The scheme involves a three-mode optomechanical system in which a pair of independent cavity modes is driven by short laser pulses and interact with a movable mirror. We demonstrate that by tuning the laser frequency to the blue (anti-Stokes) sideband of the average frequency of the cavity modes, the modes become mutually coherent and then may collectively steer the mirror mode to a perfect Einstein-Podolsky-Rosen state. The scheme is shown to be experimentally feasible, it is robust against the frequency difference between the modes, mechanical thermal noise and damping, and coupling strengths of the cavity modes to the mirror.

  15. Efficient Scheme for Perfect Collective Einstein-Podolsky-Rosen Steering

    NASA Astrophysics Data System (ADS)

    Wang, M.; Gong, Q. H.; Ficek, Z.; He, Q. Y.

    2015-07-01

    A practical scheme for the demonstration of perfect one-sided device-independent quantum secret sharing is proposed. The scheme involves a three-mode optomechanical system in which a pair of independent cavity modes is driven by short laser pulses and interact with a movable mirror. We demonstrate that by tuning the laser frequency to the blue (anti-Stokes) sideband of the average frequency of the cavity modes, the modes become mutually coherent and then may collectively steer the mirror mode to a perfect Einstein-Podolsky-Rosen state. The scheme is shown to be experimentally feasible, it is robust against the frequency difference between the modes, mechanical thermal noise and damping, and coupling strengths of the cavity modes to the mirror.

  16. Modulation recognition for variable-rate QAM schemes

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Chuan; Kuo, C.-C. Jay

    1995-12-01

    For some applications such as mobile communication or transmission of multimedia data, it is desirable to use modems with variable constellation schemes to adapt to the fast changing channel to accommodate a wide range of data transmission rates, bit error rates and data types. In this research we are interested in designing receivers which can identify the QAM constellation schemes from the received signal with an unknown reference phase. The problem is modeled as an M-ary hypothesis test with each hypothesis corresponding to one of the M possible constellation schemes. We show the performance of BPSK, QPSK, 8-PSK, 16-PSK, V.29-7200 bps, V.29-9600 bps, 16-QAM, 32-QAM, 64-QAM, 128-QAM, and 256-QAM classifiers in numerical experiments.

  17. Improved Readout Scheme for SQUID-Based Thermometry

    NASA Technical Reports Server (NTRS)

    Penanen, Konstantin

    2007-01-01

    An improved readout scheme has been proposed for high-resolution thermometers, (HRTs) based on the use of superconducting quantum interference devices (SQUIDs) to measure temperature- dependent magnetic susceptibilities. The proposed scheme would eliminate counting ambiguities that arise in the conventional scheme, while maintaining the superior magnetic-flux sensitivity of the conventional scheme. The proposed scheme is expected to be especially beneficial for HRT-based temperature control of multiplexed SQUIDbased bolometer sensor arrays. SQUID-based HRTs have become standard for measuring and controlling temperatures in the sub-nano-Kelvin temperature range in a broad range of low-temperature scientific and engineering applications. A typical SQUIDbased HRT that utilizes the conventional scheme includes a coil wound on a core made of a material that has temperature- dependent magnetic susceptibility in the temperature range of interest. The core and the coil are placed in a DC magnetic field provided either by a permanent magnet or as magnetic flux inside a superconducting outer wall. The aforementioned coil is connected to an input coil of a SQUID. Changes in temperature lead to changes in the susceptibility of the core and to changes in the magnetic flux detected by the SQUID. The SQUID readout instrumentation is capable of measuring magnetic-flux changes that correspond to temperature changes down to a noise limit .0.1 nK/Hz1/2. When the flux exceeds a few fundamental flux units, which typically corresponds to a temperature of .100 nK, the SQUID is reset. The temperature range can be greatly expanded if the reset events are carefully tracked and counted, either by a computer running appropriate software or by a dedicated piece of hardware.

  18. Ripple Clock Schemes for Quantum-dot Cellular Automata Circuits

    NASA Astrophysics Data System (ADS)

    Purohit, Prafull

    Quantum-dot cellular automata (QCA) is an emerging technology for building digital circuits at nano-scale. It is considered as an alternative to widely used complementary metal oxide semiconductor (CMOS) technology because of its key features, which include low power operation, high density and high operating frequency. Unlike conventional logic circuits in which information is transferred by electrical current, QCA operates with the help of coulomb interaction between two adjacent QCA cells. A QCA cell is a set of four quantum-dots that are placed near the corners of a square. Due to the fact that clocking provides power and control of data flow in QCA, it is considered to be the backbone of QCA operation. This thesis presents the design and simulation of a ripple clock scheme and an enhanced ripple clock scheme for QCA circuits. In the past, different clock schemes were proposed and studied which were focused on data flow in particular direction or reducing delay. This proposed thesis will study the design and simulation of new clock schemes which are more realistic for implementation, give a freedom to propagate logic in all directions, suitable for both combinational and sequential circuits and has potential to support testing and reconfiguration up to some extent. A variety of digital circuits including a 2--to--1 multiplexer, a 1--bit memory, an RS latch, a full adder, a 4--bit adder and a 2--to--4 decoder are implemented and simulated using these clock schemes. A 2--to--4 decoder is used to demonstrate the testing capabilities of these clock schemes. All QCA layouts are drawn and simulated in QCADesigner.

  19. External quality assessment scheme and laboratory accreditation in Indonesia.

    PubMed

    Timan, Ina S; Aulia, Diana; Santoso, Witono

    2002-02-01

    The National Program on External Quality Assessment Scheme (NEQAS) in Indonesia was first started in 1979, organized by the Indonesian Ministry of Health collaborating with professional bodies. The first trial was for clinical chemistry test with 2 cycles per year, followed by the hematology NEQAS in 1986 in collaboration with WHO-Royal Post Graduate Medical School London. After that, the schemes for serology, microbiology and parasitology were also organized. Around 500-600 laboratories throughout Indonesia participated each year in these quality control schemes, 2-4 cycles per year. Samples would be sent to participants and results will be given back to each laboratory. Poor performers should participate in the workshop or training course conducted by the Central Health Laboratory to improve their results. Participation in this NEQAS is mandatory for obtaining the laboratory license, and the Ministry of Health uses these schemes as one of the means for monitoring and coordinating the performance of laboratories throughout Indonesia. There are also some other EQAS (External Quality Assessment Scheme) programs conducted by professional bodies, such as for hemostasis, clinical chemistry and serology. During the course of conducting these schemes, it could be observed that manual methods were gradually changed to the automatic methods, especially for the clinical chemistry and hematology laboratories, which counts also for improvements of their results. Since the last 6 years, the Ministry of Health also began to conduct the Accreditation System evaluation for hospitals, including the laboratory departments. There are 7 standards that were evaluated, such as the aspect of the organization, administration and management, staffing, facilities and equipment, standard operating procedures, research and developments and quality control. This accreditation program is still in progress for all public and private hospital laboratories.

  20. Local ensemble assimilation scheme with global constraints and conservation

    NASA Astrophysics Data System (ADS)

    Barth, Alexander; Yan, Yajing; Canter, Martin; Alvera-Azcárate, Aida; Beckers, Jean-Marie

    2014-05-01

    Ensemble assimilation schemes applied in their original, global formulation have no problem in respecting linear conservation properties if the ensemble perturbations are setup accordingly. For realistic ocean systems, only a relatively small number of ensemble members can be calculated. A localization of the ensemble increment is thus necessary to filter out spurious long-range correlations. However, the conservation of the global property will be lost if the assimilation is performed locally since the conservation requires a coupling between model grid points, which is filtered out by the localization. In the ocean, the distribution of observations is highly inhomogeneous. Systematic errors of the observed parts of the ocean state can lead to spurious systematic adjustments of the non-observed part of the ocean state due to data assimilation. As a result, global properties which should be conserved, increase or decrease in long-term simulations. We propose an assimilation scheme (with stochastic or deterministic analysis steps) which is formulated globally (i.e. for the whole state vector) but where spurious long-range correlations can be filtered out. The scheme can thus be used to enforce global conservation properties and non-local observation operators. Both aspects are indeed linked since one can introduce the global conservation as a weak constraint by using a global observation operator. The conserved property becomes thus an observed value. The proposed scheme is tested with the Kuramoto-Sivashinsky model which is conservative. The benefit compared to the traditional covariance localization scheme (with an ad-hoc step enforcing conservation) where observations are assimilated sequentially is shown. The assimilation scheme is suitable to be implemented on parallel computers where the number of available computing cores is a multiple of the ensemble size.

  1. Seasonal predictions using a simple ocean initialization scheme

    NASA Astrophysics Data System (ADS)

    Zhu, Jieshun; Kumar, Arun; Lee, Hyun-Chul; Wang, Hui

    2017-02-01

    In this study, a simple ocean data assimilation scheme was applied to initialize a set of seasonal hindcasts, which started from each January, April, July and October during 1982-2010 with six ensemble members. In the scheme, sea surface temperature (SST) was the only observed information used to estimate the ocean initial states. Predictions of SST, 2-m temperature (T2m) and precipitation (Prate) over land were assessed and compared with hindcasts from the North American Multimodel Ensemble (NMME) project which were all based on sophisticated ocean initialization schemes with subsurface observations assimilated. The skill comparison indicated that, for all variables evaluated, the prediction skill by the simple ocean initialization procedure was well within the range of skills from individual NMME models. The result suggests that even though sophisticated initialization schemes have the potential to best capture the seasonal climate predictability, most present-day capabilities of seasonal predictions can also be accomplished by utilizing SST only. Further, significant seasonal dependence of prediction skill was also identified in hindcasts by the simple initialization scheme. Specifically, the ENSO SST predictions were featured by the significant "spring barrier" problem. It is argued that the ENSO prediction skill seasonality could be due to "double dip" contribution from the seasonality of climatic feedbacks in the tropical Pacific. In particular, these feedbacks not only play a role during the forecast leading to the largest errors in spring, but also cause the largest errors in the SST-derived ocean initial conditions in spring. Complementary aspects of seasonal forecasts based on simple initialization scheme, and use of low-resolution models are also discussed.

  2. Coupling WRF Double-Moment 6-Class Microphysics Schemes to RRTMG Radiation Scheme in Weather Research Forecasting Model

    SciTech Connect

    Bae, Soo Ya; Hong, Song-You; Lim, Kyo-Sun Sunny

    2016-01-01

    A method to explicitly calculate the effective radius of hydrometeors in the Weather Research Forecasting (WRF) double-moment 6-class (WDM6) microphysics scheme is designed to tackle the physical inconsistency in cloud properties between the microphysics and radiation processes. At each model time step, the calculated effective radii of hydrometeors from the WDM6 scheme are linked to the Rapid Radiative Transfer Model for GCMs (RRTMG) scheme to consider the cloud effects in radiative flux calculation. This coupling effect of cloud properties between the WDM6 and RRTMG algorithms is examined for a heavy rainfall event in Korea during 25–27 July 2011, and it is compared to the results from the control simulation in which the effective radius is prescribed as a constant value. It is found that the derived radii of hydrometeors in the WDM6 scheme are generally larger than the prescribed values in the RRTMG scheme. Consequently, shortwave fluxes reaching the ground (SWDOWN) are increased over less cloudy regions, showing a better agreement with a satellite image. The overall distribution of the 24-hour accumulated rainfall is not affected but its amount is changed. A spurious rainfall peak over the Yellow Sea is alleviated, whereas the local maximum in the central part of the peninsula is increased.

  3. Coupling WRF double-moment 6-class microphysics schemes to RRTMG radiation scheme in weather research forecasting model

    DOE PAGES

    Bae, Soo Ya; Hong, Song -You; Lim, Kyo-Sun Sunny

    2016-01-01

    A method to explicitly calculate the effective radius of hydrometeors in the Weather Research Forecasting (WRF) double-moment 6-class (WDM6) microphysics scheme is designed to tackle the physical inconsistency in cloud properties between the microphysics and radiation processes. At each model time step, the calculated effective radii of hydrometeors from the WDM6 scheme are linked to the Rapid Radiative Transfer Model for GCMs (RRTMG) scheme to consider the cloud effects in radiative flux calculation. This coupling effect of cloud properties between the WDM6 and RRTMG algorithms is examined for a heavy rainfall event in Korea during 25–27 July 2011, and itmore » is compared to the results from the control simulation in which the effective radius is prescribed as a constant value. It is found that the derived radii of hydrometeors in the WDM6 scheme are generally larger than the prescribed values in the RRTMG scheme. Consequently, shortwave fluxes reaching the ground (SWDOWN) are increased over less cloudy regions, showing a better agreement with a satellite image. The overall distribution of the 24-hour accumulated rainfall is not affected but its amount is changed. In conclusion, a spurious rainfall peak over the Yellow Sea is alleviated, whereas the local maximum in the central part of the peninsula is increased.« less

  4. Coupling WRF double-moment 6-class microphysics schemes to RRTMG radiation scheme in weather research forecasting model

    SciTech Connect

    Bae, Soo Ya; Hong, Song -You; Lim, Kyo-Sun Sunny

    2016-01-01

    A method to explicitly calculate the effective radius of hydrometeors in the Weather Research Forecasting (WRF) double-moment 6-class (WDM6) microphysics scheme is designed to tackle the physical inconsistency in cloud properties between the microphysics and radiation processes. At each model time step, the calculated effective radii of hydrometeors from the WDM6 scheme are linked to the Rapid Radiative Transfer Model for GCMs (RRTMG) scheme to consider the cloud effects in radiative flux calculation. This coupling effect of cloud properties between the WDM6 and RRTMG algorithms is examined for a heavy rainfall event in Korea during 25–27 July 2011, and it is compared to the results from the control simulation in which the effective radius is prescribed as a constant value. It is found that the derived radii of hydrometeors in the WDM6 scheme are generally larger than the prescribed values in the RRTMG scheme. Consequently, shortwave fluxes reaching the ground (SWDOWN) are increased over less cloudy regions, showing a better agreement with a satellite image. The overall distribution of the 24-hour accumulated rainfall is not affected but its amount is changed. In conclusion, a spurious rainfall peak over the Yellow Sea is alleviated, whereas the local maximum in the central part of the peninsula is increased.

  5. A Neutral Plasma Source for Active Spacecraft Charge Control.

    DTIC Science & Technology

    1985-08-01

    potentials are generally negative since electrons have higher mobilities as compared to ions. Overall spacecraft frame charging enhances surface contamination...Cuchanski, M., Kremer, P. C., "Surface Micro-Discharges on Spacecraft Dielectrics", Paper 111-7, Proceedings of the Spacecraft Charging Techonology

  6. Charge-Controlled Colloids on Liquid-Liquid Interfaces

    NASA Astrophysics Data System (ADS)

    Kunz, Daniel A.; Reck, Bernd; Manoharan, Vinothan N.

    2014-03-01

    The tendency of colloidal particles to stabilize interfaces has been exploited for many years to generate Pickering emulsions with a variety of industrial applications. However, the exact stabilization mechanism and its dependence on the surface properties of the colloidal particles are not yet fully understood. We provide new interfacial studies on the nonequilibrium dynamics of a colloidal system with tunable surface charge density. We push individual sub-micron colloidal particles towards an oil-water interface and track their motion in three-dimensions using holographic microscopy to examine the influence of zeta potential on the dynamics of the system. This project was funded by the BASF Advanced Research Initiative, BASF SE, Germany.

  7. Design and Evaluation of Ion Source for Satellite Charge Control

    DTIC Science & Technology

    1992-06-01

    Plasma Clouds in the Magnetosphere ," Journal of Geophysical Research, v. 76, 1971. DeForest, S.E., " Spacecraft Charging at Synchronous... Charging : A Review," Progress in Astronautics and Aeronautics, v. 71, pp. 167-226, 1980. Grard,R., Knott, K., and Pederson, A., Spacecraft Charging ...Satellite Program," Spacecraft Charging by Magnetospheric Plasmas , v.47, AIAA, ed. A. Rosen, AIAA with MIT Press, 1976. Moore, J.H., Davis, C.C.,

  8. Satellite Charge Control with Lithium Ion Source and Electron Emission

    DTIC Science & Technology

    1990-12-01

    HtO Ni 26.8 2.77 5.01-4.12 32,100 2900 RIO Air, Ut NiO 0.1 X 10- 2 4.87 Pb ...................... [4.1-3.51 ..... 1620 Pd ............ 4.99 4.96...impregnant from the pores of the tungst .:n body. This blooming can be easily brushed away should it occur. The only negative effect caused by blooming

  9. Use of charging control guidelines for geosynchronous satellite design studies

    NASA Technical Reports Server (NTRS)

    Steves, N. J.

    1980-01-01

    Several of the principle guidelines from the Spacecraft Charging Design Guidelines Handbook are presented with illustrative examples. Use of the geomagnetic substorm specification to qualify satellite designs, the evaluation of satellite designs by using analytical modelling techniques, the use of selected materials and coatings to minimize charging, the tying of all conducting elements to a common ground, and the use of electrical filtering to protect circuits from discharge induced upsets are discussed. Discharge criteria and SCATHA data are excluded.

  10. Price Incentivised Electric Vehicle Charge Control for Community Voltage Regulation

    SciTech Connect

    Kelly, Damian; Baroncelli, Fabio; Fowler, Christopher; Boundy, David; Pratt, Annabelle

    2014-11-03

    With the growing availability of Electric Vehicles, there is a significant opportunity to use battery 'smart-charging' for voltage regulation. This work designs and experimentally evaluates a system for price-incentivised electric vehicle charging. The system is designed to eliminate negative impacts to the user while minimising the cost of charging and achieving a more favourable voltage behaviour throughout the local grid over time. The practical issues associated with a real-life deployment are identified and resolved. The efficacy of the system is evaluated in the challenging scenario in which EVs are deployed in six closely distributed homes, serviced by the same low voltage residential distribution feeder.

  11. Charge Control of Geosynchronous Spacecraft Using Field Effect Emitters

    DTIC Science & Technology

    2007-01-01

    conductivity of cold coverglasses are likely ingredients leading to ESD . However, the emitter maintains a normal gradient potential on the solar arrays, so the...potential of about +5 volts, leading to a " normal gradient " differential potential of about 40 volts. Because kilovolt potentials are required to cause...electrostatic discharges in the " normal gradient " configuration, the coverglass differential potential is not cause for concern. The shaded OSRs are charged

  12. Materials and techniques for spacecraft static charge control

    NASA Technical Reports Server (NTRS)

    Amore, L. J.; Eagles, A. E.

    1977-01-01

    An overview of the design, development, fabrication, and testing of transparent conductive coatings and conductive lattices deposited or formed on high resistivity spacecraft dielectric materials to obtain control static charge buildup on spacecraft external surfaces is presented. Fabrication techniques for the deposition of indium/tin oxide coatings and copper grid networks on Kapton and FEP Teflon films and special frit coatings for OSR and solar cell cover glasses are discussed. The techniques include sputtering, photoetching, silkscreening, and mechanical processes. A facility designed and built to simulate the electron plasma at geosynchronous altitudes is described along with test procedures. The results of material characterizations as well as electron irradiation aging effects in this facility for spacecraft polymers treated to control static charge are presented. The data presents results for electron beam energies up to 30 kV and electron current densities of 30 nA/cm squared. Parameters measured include secondary emission, surface leakage, and through the sample currents as a function of primary beam energy and voltage.

  13. Charge control switch responsive to cell casing deflection

    NASA Technical Reports Server (NTRS)

    Fischell, Robert E. (Inventor)

    1981-01-01

    A switch structure, adapted for sensing the state-of-charge of a rechargeable cell, includes a contact element which detects cell casing deflection that occurs as a result of an increase in gaseous pressure within the cell when the cell is returned to its fully charged state during a recharging operation.

  14. Fourier analysis of finite element preconditioned collocation schemes

    NASA Technical Reports Server (NTRS)

    Deville, Michel O.; Mund, Ernest H.

    1990-01-01

    The spectrum of the iteration operator of some finite element preconditioned Fourier collocation schemes is investigated. The first part of the paper analyses one-dimensional elliptic and hyperbolic model problems and the advection-diffusion equation. Analytical expressions of the eigenvalues are obtained with use of symbolic computation. The second part of the paper considers the set of one-dimensional differential equations resulting from Fourier analysis (in the tranverse direction) of the 2-D Stokes problem. All results agree with previous conclusions on the numerical efficiency of finite element preconditioning schemes.

  15. Sparse grid techniques for particle-in-cell schemes

    NASA Astrophysics Data System (ADS)

    Ricketson, L. F.; Cerfon, A. J.

    2017-02-01

    We propose the use of sparse grids to accelerate particle-in-cell (PIC) schemes. By using the so-called ‘combination technique’ from the sparse grids literature, we are able to dramatically increase the size of the spatial cells in multi-dimensional PIC schemes while paying only a slight penalty in grid-based error. The resulting increase in cell size allows us to reduce the statistical noise in the simulation without increasing total particle number. We present initial proof-of-principle results from test cases in two and three dimensions that demonstrate the new scheme’s efficiency, both in terms of computation time and memory usage.

  16. A joint asymmetric watermarking and image encryption scheme

    NASA Astrophysics Data System (ADS)

    Boato, G.; Conotter, V.; De Natale, F. G. B.; Fontanari, C.

    2008-02-01

    Here we introduce a novel watermarking paradigm designed to be both asymmetric, i.e., involving a private key for embedding and a public key for detection, and commutative with a suitable encryption scheme, allowing both to cipher watermarked data and to mark encrypted data without interphering with the detection process. In order to demonstrate the effectiveness of the above principles, we present an explicit example where the watermarking part, based on elementary linear algebra, and the encryption part, exploiting a secret random permutation, are integrated in a commutative scheme.

  17. Revisit to the THINC scheme: A simple algebraic VOF algorithm

    NASA Astrophysics Data System (ADS)

    Xiao, Feng; , Satoshi, Ii; Chen, Chungang

    2011-08-01

    This short note presents an improved multi-dimensional algebraic VOF method to capture moving interfaces. The interface jump in the THINC (tangent of hyperbola for INterface capturing) scheme is adaptively scaled to a proper thickness according to the interface orientation. The numerical accuracy in computing multi-dimensional moving interfaces is significantly improved. Without any geometrical reconstruction, the proposed method is extremely simple and easy to use, and its numerical accuracy is superior to other existing methods of its kind and comparable to the conventional PLIC (piecewise linear interface calculation) type VOF schemes.

  18. Packet Forwarding Scheme Based on Interworking Architecture for Future Internet

    NASA Astrophysics Data System (ADS)

    Kim, Seokhoon; Ryoo, Intae

    This paper introduces a packet forwarding scheme based on interworking architecture that can provide quite a good QoS by minimizing processing delay which is the major part of the timeliness factor in New Generation IP-based networks. Based on path and resource reservation mechanism, the POSIA makes routers on the packet forwarding path synchronize with each other and then forward packets. We have shown that the POSIA outperforms the existing packet forwarding schemes like IntServ, DiffServ and MPLS through computer simulations using OPNET.

  19. A rotationally biased upwind difference scheme for the Euler equations

    NASA Technical Reports Server (NTRS)

    Davis, S. F.

    1983-01-01

    The upwind difference schemes of Godunov, Osher, Roe and van Leer are able to resolve one dimensional steady shocks for the Euler equations within one or two mesh intervals. Unfortunately, this resolution is lost in two dimensions when the shock crosses the computing grid at an oblique angle. To correct this problem, a numerical scheme was developed which automatically locates the angle at which a shock might be expected to cross the computing grid and then constructs separate finite difference formulas for the flux components normal and tangential to this direction. Numerical results which illustrate the ability of this method to resolve steady oblique shocks are presented.

  20. A secret image sharing scheme for light images

    NASA Astrophysics Data System (ADS)

    Wu, Kuang-Shyr

    2013-12-01

    In this study, a new ( r, n)-threshold secret image sharing scheme with low information overhead for images is provided, which has a low distortion rate, and is more applicable for light images. A secret image is encoded into n noise-like shadow images to satisfy the condition that any r of the n shares can be used to reveal the secret image, and no information on the secret can be revealed from any r - 1 or fewer shares. The size of the shadow images is relatively small. The experimental results show the effectiveness of the proposed scheme.

  1. A secure quantum group signature scheme based on Bell states

    NASA Astrophysics Data System (ADS)

    Zhang, Kejia; Song, Tingting; Zuo, Huijuan; Zhang, Weiwei

    2013-04-01

    In this paper, we propose a new secure quantum group signature with Bell states, which may have applications in e-payment system, e-government, e-business, etc. Compared with the recent quantum group signature protocols, our scheme is focused on the most general situation in practice, i.e. only the arbitrator is trusted and no intermediate information needs to be stored in the signing phase to ensure the security. Furthermore, our scheme has achieved all the characteristics of group signature—anonymity, verifiability, traceability, unforgetability and undeniability, by using some current developed quantum and classical technologies. Finally, a feasible security analysis model for quantum group signature is presented.

  2. 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

  3. On the application and extension of Harten's high resolution scheme

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Warming, R. F.; Harten, A.

    1982-01-01

    Extensions of a second order high resolution explicit method for the numerical computation of weak solutions of one dimensonal hyperbolic conservation laws are discussed. The main objectives were (1) to examine the shock resoluton of Harten's method for a two dimensional shock reflection problem, (2) to study the use of a high resolution scheme as a post-processor to an approximate steady state solution, and (3) to construct an implicit in the delta-form using Harten's scheme for the explicit operator and a simplified iteration matrix for the implicit operator.

  4. Adaptive mobility management scheme in hierarchical mobile IPv6

    NASA Astrophysics Data System (ADS)

    Fang, Bo; Song, Junde

    2004-04-01

    Hierarchical mobile IPv6 makes the mobility management localized. Registration with HA is only needed while MN moving between MAP domains. This paper proposed an adaptive mobility management scheme based on the hierarchical mobile IPv6. The scheme focuses on the MN operation as well as MAP operation during the handoff. Adaptive MAP selection algorithm can be used to select a suitable MAP to register with once MN moves into a new subnet while MAP can thus adaptively changing his management domain. Furthermore, MAP can also adaptively changes its level in the hierarchical referring on the service load or other related information. Detailed handoff algorithm is also discussed in this paper.

  5. 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.

  6. A review of thrust-vectoring schemes for fighter applications

    NASA Technical Reports Server (NTRS)

    Berrier, B. L.; Re, R. J.

    1978-01-01

    This paper presents a review of thrust vectoring schemes for advanced fighter applications. Results are presented from wind tunnel and system integration studies on thrust vectoring nozzle concepts. Vectoring data are presented from wind tunnel tests of axisymmetric C-D (convergent-divergent) and nonaxisymmetric wedge, C-D, single ramp and USB (upper-surface blowing) nozzle concepts. Results from recent airframe/nozzle integration studies on the impact of thrust vectoring on weight, cooling and performance characteristics are discussed. This review indicates that the aircraft designer has, at his disposal, a wide range of thrust vectoring schemes which offer potential for added or improved aircraft capability.

  7. A Comparison of three high-precision quadrature schemes

    SciTech Connect

    Bailey, David H.; Li, Xiaoye S.

    2003-07-01

    The authors have implemented three numerical quadrature schemes, using the new Arbitrary Precision (ARPREC) software package, with the objective of seeking a completely ''automatic'' arbitrary precision quadrature facility, namely one that does not rely on a priori information of the function to be integrated. Such a facility is required, for example, to permit the experimental identification of definite integrals based on their numerical values. The performance and accuracy of these three quadrature schemes are compared using a suite of 15 integrals, ranging from continuous, well-behaved functions on finite intervals to functions with vertical derivatives and integrable singularities at endpoints, as well as several integrals on an infinite interval.

  8. An Enhanced Facet Determination Scheme in 3D

    NASA Astrophysics Data System (ADS)

    Reivinen, M.; Salonen, E.-M.; Todoshchenko, I.; Vaskelainen, V. P.

    2017-01-01

    An enhanced scheme for the determination of equilibrium crystal shapes is introduced. The emphasis of the present study is put on the proper detection of the facets appearing on the crystal surface. The original formulation presented in [1] employs the principle of the virtual work, and the enhanced scheme additionally makes use of a penalty formulation approach. The derivation of the penalty terms is discussed in detail. Finally, the corresponding discrete method is applied to a certain problematic example case presented in [1] resulting now in the correct crystal shape.

  9. The Spanish external quality assessment scheme for mercury in urine.

    PubMed

    Quintana, M J; Mazarrasa, O

    1996-01-01

    In 1986 the Instituto Nacional de Seguridad e Higiene en el Trabajo (INSHT), established the "Programa interlaboratorios de control de calidad de mercurio en orina (PICC-HgU)". The operation of this scheme is explained, criteria for evaluation of laboratory performance are defined and some results obtained are reviewed. Since the scheme started, an improvement in the overall performance of laboratories has been observed. The differences in the analytical methods used by laboratories do not seem to have a clear influence on the results.

  10. A Parallel Multiblock Mesh Movement Scheme For Complex Aeroelastic Applications

    NASA Technical Reports Server (NTRS)

    Potsdam, Mark A.; Guruswamy, Guru P.

    2000-01-01

    A scheme has been developed for the movement of multiblock, structured grids due to surface deformation arising from aeroelastics, control surface movement, or design optimization. Elements of the method include a blending of a surface spline approximation and nearest surface point movement for block boundaries. Transfinite interpolation is employed for volume grid deformation. The scheme is demonstrated on a range of simple and complex aeroelastic aircraft applications using Navier-Stokes computational fluid dynamics and modal structural analyses on parallel processors. Results are robust and accurate, requiring only minimal user input specification.

  11. Crab Crossing Schemes and Studies for Electron Ion Collider

    SciTech Connect

    S. Ahmed, Y. Derbenev, V. Morozov, A. Castilla, G.A. Krafft, B. Yunn, Y. Zhang, J.R. Delayen

    2011-09-01

    This report shows our progress in crab crossing consideration for future electron-ion collider envisioned at JLab. In this design phase, we are evaluating two crabbing schemes viz., the deflecting and dispersive. The mathematical formulations and lattice design for these schemes are discussed in this paper. Numerical simulations involving particle tracking through a realistic deflecting RF cavity and optics illustrate the desired crab tilt of 25 mrad for 1.35 MV. Evolution of beam propagation are shown which provides the physical insight of the crabbing phenomenon.

  12. Iterative schemes for nonsymmetric and indefinite elliptic boundary value problems

    SciTech Connect

    Bramble, J.H.; Leyk, Z.; Pasciak, J.E.

    1993-01-01

    The purpose of this paper is twofold. The first is to describe some simple and robust iterative schemes for nonsymmetric and indefinite elliptic boundary value problems. The schemes are based in the Sobolev space H ([Omega]) and require minimal hypotheses. The second is to develop algorithms utilizing a coarse-grid approximation. This leads to iteration matrices whose eigenvalues lie in the right half of the complex plane. In fact, for symmetric indefinite problems, the iteration is reduced to a well-conditioned symmetric positive definite system which can be solved by conjugate gradient interation. Applications of the general theory as well as numerical examples are given. 20 refs., 8 tabs.

  13. General mass scheme for jet production in DIS

    NASA Astrophysics Data System (ADS)

    Kotko, P.; Slominski, W.

    2012-11-01

    We propose a method for calculating DIS jet production cross sections in QCD at NLO accuracy with consistent treatment of heavy quarks. The scheme relies on the dipole subtraction method for jets, which we extend to all possible initial state splittings with heavy partons, so that the Aivazis-Collins-Olness-Tung massive collinear factorization scheme can be applied. As a first check of the formalism we recover the Aivazis-Collins-Olness-Tung result for the heavy quark structure function using a dedicated Monte Carlo program.

  14. Block-based adaptive lifting schemes for multiband image compression

    NASA Astrophysics Data System (ADS)

    Masmoudi, Hela; Benazza-Benyahia, Amel; Pesquet, Jean-Christophe

    2004-02-01

    In this paper, we are interested in designing lifting schemes adapted to the statistics of the wavelet coefficients of multiband images for compression applications. More precisely, nonseparable vector lifting schemes are used in order to capture simultaneously the spatial and the spectral redundancies. The underlying operators are then computed in order to minimize the entropy of the resulting multiresolution representation. To this respect, we have developed a new iterative block-based classification algorithm. Simulation tests carried out on remotely sensed multispectral images indicate that a substantial gain in terms of bit-rate is achieved by the proposed adaptive coding method w.r.t the non-adaptive one.

  15. A Microprocessor Control Scheme For Switched Reluctance Motor Drives

    NASA Astrophysics Data System (ADS)

    Oza, A. R.; Krishnan, R.; Adkar, S.

    1987-10-01

    A microprocessor control scheme for a switched reluctance motor(SRM) drive is discussed. A SRM is inherently a variable speed machine since it requires a converter even for constant speed running. Starting with a conceptual development, a particular hardware scheme is discussed for controller implementation. Hardware-software tradeoffs incorporated in the design are discussed. Some results of an actual system are evaluated. It is shown that a microprocessor controller has many advantages over conventional controllers. The controller design uses rotor position and speed feedbacks. Self-starting is incorporated into the design. Use of off-the-shelf components makes the controller simple, reliable, and economical.

  16. A second order derivative scheme based on Bregman algorithm class

    NASA Astrophysics Data System (ADS)

    Campagna, Rosanna; Crisci, Serena; Cuomo, Salvatore; Galletti, Ardelio; Marcellino, Livia

    2016-10-01

    The algorithms based on the Bregman iterative regularization are known for efficiently solving convex constraint optimization problems. In this paper, we introduce a second order derivative scheme for the class of Bregman algorithms. Its properties of convergence and stability are investigated by means of numerical evidences. Moreover, we apply the proposed scheme to an isotropic Total Variation (TV) problem arising out of the Magnetic Resonance Image (MRI) denoising. Experimental results confirm that our algorithm has good performance in terms of denoising quality, effectiveness and robustness.

  17. Performance Analysis of FSO Communication Using Different Coding Schemes

    NASA Astrophysics Data System (ADS)

    Gupta, Nidhi; Prakash, Siddi Jai; Kaushal, Hemani; Jain, V. K.; Kar, Subrat

    2011-10-01

    A major impairment in Free Space Optical (FSO) links is the turbulence induced fading which severely degrades the link performance. To mitigate turbulence induced fading and, therefore, to improve the error rate performance, error control coding schemes can be used. In this paper, we investigate the bit error performance of FSO links with different coding techniques over log normal atmospheric turbulence fading channels. The modulation scheme considered is BPSK. On the basis of computed results using Monte Carlo simulation, a comparative study of uncoded and coded systems is made.

  18. Powered-descent trajectory optimization scheme for Mars landing

    NASA Astrophysics Data System (ADS)

    Liu, Rongjie; Li, Shihua; Chen, Xisong; Guo, Lei

    2013-12-01

    This paper presents a trajectory optimization scheme for powered-descent phase of Mars landing with considerations of disturbance. Firstly, θ-D method is applied to design a suboptimal control law with descent model in the absence of disturbance. Secondly, disturbance is estimated by disturbance observer, and the disturbance estimation is as feedforward compensation. Then, semi-global stability analysis of the composite controller consisting of the nonlinear suboptimal controller and the disturbance feedforward compensation is proposed. Finally, to verify the effectiveness of proposed control scheme, an application including relevant simulations on a Mars landing mission is demonstrated.

  19. A new quantum scheme for normal-form games

    NASA Astrophysics Data System (ADS)

    Fraçkiewicz, Piotr

    2015-06-01

    We give a strict mathematical description for a refinement of the Marinatto-Weber quantum game scheme. The model allows the players to choose projector operators that determine the state on which they perform their local operators. The game induced by the scheme generalizes finite strategic-form game. In particular, it covers normal representations of extensive games, i.e., strategic games generated by extensive ones. We illustrate our idea with an example of extensive game and prove that rational choices in the classical game and its quantum counterpart may lead to significantly different outcomes.

  20. A convexity preserving scheme for conservative advection transport

    NASA Astrophysics Data System (ADS)

    Xiao, Feng; Peng, Xindong

    2004-08-01

    A simple and practical scheme for advection transport equation is presented. The scheme, namely piecewise rational method (PRM), is a variant of the existing piecewise parabolic method (PPM) of Colella and Woodward (1984). Instead of the parabolic function, a rational function is used for the reconstruction. Making use of the convexity preserving nature of the rational function enables us to obtain oscillation-less numerical solutions, but avoids the adjustments of the cell-interface values to enforce the monotonicity in PPM. The PRM is very simple and computationally efficient. Our numerical results show that PRM is competitive to the PPM in many aspects, such as numerical accuracy and shape-preserving property.