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Sample records for model low-altitude component

  1. Low Altitude Validation of Geomagnetic Cutoff Models Using SAMPEX Data

    Science.gov (United States)

    Young, S. L.; Kress, B. T.

    2011-12-01

    Single event upsets (SEUs) caused by MeV protons are a concern for satellite operators so AFRL is working to create a tool that can specify and/or forecast SEU probabilities. An important component of the tool's SEU probability calculation will be the local energetic ion spectrum. The portion of that spectrum due to trapped energetic ion population is relatively stable and predictable; however it is more difficult to account for the transient solar energetic particles (SEPs). These particles, which can be ejected from the solar atmosphere during a solar flare or filament eruption or can be energized by coronal mass ejection (CME) driven shocks, can penetrate the Earth's magnetosphere into regions not normally populated by energetic protons. The magnetosphere will provide energy dependent shielding that also depends on its magnetic configuration. During magnetic storms that configuration is modified and the SEP cutoff latitude for a given particle energy can be suppressed up to ~15 degrees equatorward exposing normally shielded regions. As a first step to creating the satellite SEU prediction tool, we are comparing the Smart et al. (Advances in Space Research, 2006) and CISM-Dartmouth (Kress et al., Space Weather, 2010) geomagnetic cutoff tools. While they have provided some of their own validations in the noted papers, our validation will be done consistently between models allowing us to better compare the models.

  2. Modelling circumplanetary ejecta clouds at low altitudes: a probabilistic approach

    CERN Document Server

    Christou, Apostolos A

    2014-01-01

    A model is presented of a ballistic, collisionless, steady state population of ejecta launched at randomly distributed times and velocities and moving under constant gravity above the surface of an airless planetary body. Within a probabilistic framework, closed form solutions are derived for the probability density functions of the altitude distribution of particles, the distribution of their speeds in a rest frame both at the surface and at altitude and with respect to a moving platform such as an orbiting spacecraft. These expressions are validated against numerically-generated synthetic populations of ejecta under lunar surface gravity. The model is applied to the cases where the ejection speed distribution is (a) uniform (b) a power law. For the latter law, it is found that the effective scale height of the ejecta envelope directly depends on the exponent of the power law and increases with altitude. The same holds for the speed distribution of particles near the surface. Ejection model parameters can, t...

  3. Poynting flux-conserving low-altitude boundary conditions for global magnetospheric models

    Science.gov (United States)

    Xi, S.; Lotko, W.; Zhang, B.; Brambles, O. J.; Lyon, J. G.; Merkin, V. G.; Wiltberger, M.

    2015-01-01

    A method for specifying low-altitude or inner boundary conditions that conserve low-frequency, magnetic field-aligned, electromagnetic energy flux across the boundary in global magnetospheric magnetohydrodynamics (MHD) models is presented. The single-fluid Lyon-Fedder-Mobarry (LFM) model is used to verify this method, with comparisons between simulations using LFM's standard hardwall boundary conditions and the new flux-conserving boundary conditions. Identical idealized upstream solar wind and interplanetary magnetic field conditions and the same constant ionospheric conductance are used in both runs. The results show that, compared to LFM's standard hardwall boundary conditions, the flux-conserving method improves the transparency of the boundary for the flow of low-frequency (essentially DC) electromagnetic energy flux along field lines. As a consequence, the hemispheric integrated field-aligned DC Poynting flux just above the boundary is close to the hemispheric total Joule heating of the ionosphere, as it should be if electromagnetic energy is conserved. The MHD velocity and perpendicular currents are well-behaved near the inner boundary for the flux conserving boundary conditions.

  4. Low altitude remote sensing

    NARCIS (Netherlands)

    Pérez Calero, D.; Peyaud, A.; Van der Wal, D.; van 't Hof, J.; Hakkesteegt, H.; Vink, R.; Bovenkamp, E.G.P.; van Antwerpen, G.; Meynart, R.; Neeck, S.P.; Shimoda, H.; Habib, S.

    2008-01-01

    In 2007 TNO started to fly some sensors on an unmanned helicopter platform. These sensors included RGB, B/W and thermal infrared cameras. In 2008 a spectrometer was added. The goal for 2010 is to be able to offer a low altitude flying platform including several sensors. Development of these sensors

  5. Semi-empirical thermosphere model evaluation at low altitude with GOCE densities

    Science.gov (United States)

    Bruinsma, Sean; Arnold, Daniel; Jäggi, Adrian; Sánchez-Ortiz, Noelia

    2017-02-01

    Aims: The quality of the Committee on Space Research (COSPAR) International Reference Atmosphere models NRLMSISE-00, JB2008, and DTM2013 in the 150-300 km altitude range has never been thoroughly evaluated due to a lack of good density data. This study aims at providing the model accuracies thanks to the recent high-resolution high-accuracy Gravity field and steady-state Ocean Circulation Explorer (GOCE) density dataset. The evaluation was performed on yearly, monthly, and daily time scales, which are important for different applications such as mission design, mission operation, or re-entry predictions. Methods: The accuracy of the models was evaluated by comparing to the GOCE density observations of the Science Mission (1 November 2009-20 October 2013) and new density data at the lowest altitudes derived for the last weeks before the re-entry (22 October-8 November 2013) according to a metric, which consists of computing mean, standard deviation and root mean square (RMS) of the observed-to-model ratios, and correlation. Mean statistics are then calculated over the three time scales. Results: The range of model biases, standard deviations, and correlations becomes larger when the time interval decreases, and this study provides COSPAR International Reference Atmosphere (CIRA) model statistics in the altitude range of 275-170 km. DTM2013 is the least biased and most accurate model on all time scales, essentially thanks to the database, notably containing two years of GOCE densities, to which it was fitted. NRLMSISE-00 performs worst, with considerable bias of about 20% in 2009 and 2013, and systematically higher standard deviations (lower correlations) than JB2008 and DTM2013. The performance of JB2008 is presently only slightly behind DTM2013, thanks to the new release 4_2g solar activity proxies. However, it still presents some weakness under the lowest solar activity conditions in 2009 and 2010. Comparison to Challenging Mini-Satellite Payload (CHAMP) density

  6. Dynamics modeling and control of a transport aircraft for ultra-low altitude airdrop

    Directory of Open Access Journals (Sweden)

    Liu Ri

    2015-04-01

    Full Text Available The nonlinear aircraft model with heavy cargo moving inside is derived by using the separation body method, which can describe the influence of the moving cargo on the aircraft attitude and altitude accurately. Furthermore, the nonlinear system is decoupled and linearized through the input–output feedback linearization method. On this basis, an iterative quasi-sliding mode (SM flight controller for speed and pitch angle control is proposed. At the first-level SM, a global dynamic switching function is introduced thus eliminating the reaching phase of the sliding motion. At the second-level SM, a nonlinear function with the property of “smaller errors correspond to bigger gains and bigger errors correspond to saturated gains” is designed to form an integral sliding manifold, and the overcompensation of the integral term to big errors is weakened. Lyapunov-based analysis shows that the controller with strong robustness can reject both constant and time-varying model uncertainties. The performance of the proposed control strategy is verified in a maximum load airdrop mission.

  7. Can periodicity in low altitude cloud cover be induced by cosmic ray variability in the extragalactic shock model?

    CERN Document Server

    Atri, Dimitra; Melott, Adrian L; Kansas, University of; University, Washburn

    2010-01-01

    Variation in high energy cosmic rays (HECRs) has been proposed to explain a 62 My periodicity in terrestrial fossil biodiversity. It has been suggested that the infall of our galaxy toward the Virgo cluster could generate an extragalactic shock, accelerating charged particles and exposing the earth to a flux of high energy cosmic rays (HECRs). The oscillation of the Sun perpendicular to the galactic plane could induce 62 My periodicity in the HECR flux on the Earth, with a magnitude much higher than the Galactic cosmic ray change we see in a solar cycle. This mechanism could potentially explain the observed 62 My periodicity in terrestrial biodiversity over the past 500 My. In addition to direct effects on life from secondaries, HECRs induced air showers ionize the atmosphere leading to changes in atmospheric chemistry and microphysical processes that can lead to cloud formation including low altitude cloud cover. An increase in ionization changes the global electric circuit which could enhance the formation ...

  8. Influence of low-altitude meteorological conditions on local infrasound propagation investigated by 3-D full-waveform modeling

    Science.gov (United States)

    Kim, Keehoon; Rodgers, Arthur

    2017-08-01

    Vertical stratification in the low atmosphere impacts near-ground sound propagation. On clear days, for example, negative gradients of low-atmospheric temperature can lead to upward refraction of acoustic waves and create a zone of silence near the ground, where no acoustic rays can arrive. We investigate impacts of lower tropospheric temperature and wind-velocity gradient on acoustic wave propagation using numerical simulations. Sound refraction in the atmosphere is a frequency-dependent wave phenomenon, and therefore classical ray methods based on infinite-frequency approximation may not be suitable for modeling acoustic wave amplitudes. In this study, a full-waveform acoustic solver was used to predict amplitudes of acoustic waves taking into account meteorological conditions (temperature, pressure and wind). Local radiosonde sounding data were input into acoustic simulations to characterize the background conditions of the local atmosphere. The results of numerical modeling indicate that acoustic overpressure amplitudes were significantly affected by local atmospheric wind speed and direction near the ground. Local wind changes the effective sound speed profile in the atmosphere and influences overpressure amplitude decay governed by upward refraction. We compared 3-D finite-difference modeling results with acoustic overpressure measurements from the Humming Roadrunner explosion experiments conducted in New Mexico in 2012. The modeling results showed good agreement with the observations in peak amplitudes when a background wind was weak and well characterized by local atmospheric data. However, when a strong wind was present at an explosion and its variability was poorly characterized by local radiosonde sounding, the numerical prediction of local acoustic amplitude agreed poorly with the observations. Additional numerical simulations with the inclusion of surface wind data indicate that local acoustic amplitudes could be significantly variable depending on

  9. Low altitude dose measurements from APEX, CRRES and DMSP.

    Science.gov (United States)

    Mullen, E G; Gussenhoven, M S; Bell, J T; Madden, D; Holeman, E; Delorey, D

    1998-01-01

    Dosimeter data taken on the APEX (1994-1996), CRRES (1990-1991) and DMSP (1984-1987) satellites have been used to study the low altitude (down to 350 km) radiation environment. Of special concern has been the inner edge of the inner radiation belt due to its steep gradient. We have constructed dose models of the inner edge of the belt from all three spacecraft and put them into a personal computer utility, called APEXRAD, that calculates dose for user-selected orbits. The variation of dose for low altitude, circular orbits is given as a function of altitude, inclination and particle type. Dose-depth curves show that shielding greater than approximately 1/4 in Al is largely ineffectual for low altitude orbits. The contribution of outer zone electrons to low altitude dose is shown to be important only for thin shields and to have significant variation with magnetic activity and solar cycle.

  10. Analytical estimate for low-altitude ENA emissivity

    Science.gov (United States)

    Goldstein, J.; Bisikalo, D. V.; Shematovich, V. I.; Gérard, J.-C.; Søraas, F.; McComas, D. J.; Valek, P. W.; LLera, K.; Redfern, J.

    2016-02-01

    We formulate the first analytical model for energetic neutral atom (ENA) emissivity that partially corrects for the global viewing geometry dependence of low-altitude emissions (LAEs) observed by Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS). The emissivity correction requires the pitch angle distribution (PAD) and geophysical location of low-altitude ENAs. To estimate PAD, we create an energy-dependent analytical model, based on a Monte Carlo simulation. We account for energy binning by integrating model PAD over each energy bin. We account for finite angular pixels by computing emissivity as an integral over the pitch angle range sampled by the pixel. We investigate location uncertainty in TWINS pixels by performing nine variations of the emissivity calculation. Using TWINS 2 ENA imaging data from 1131 to 1145 UT on 6 April 2010, we derive emissivity-corrected ion fluxes for two angular pixel sizes: 4° and 1°. To evaluate the method, we compare TWINS-derived ion fluxes to simultaneous in situ data from the National Oceanic and Atmospheric Administration (NOAA) 17 satellite. The TWINS-NOAA agreement for emissivity-corrected flux is improved by up to a factor of 7, compared to uncorrected flux. The highest 1° pixel fluxes are a factor of 2 higher than for 4° pixels, consistent with pixel-derived fluxes that are artificially low because subpixel structures are smoothed out, and indicating a possible slight advantage to oversampling the instrument-measured LAE signal. Both TWINS and NOAA ion fluxes decrease westward of 2000 magnetic local time. The TWINS-NOAA comparison indicates that the global ion precipitation oval comprises multiple smaller-scale (3-5° of latitude) structures.

  11. Investigation of Correction Method of the Spacecraft Low Altitude Ranging

    CERN Document Server

    Liu, Jing-Lei; Wu, Shi-Tong; Huang, Wei

    2015-01-01

    gamma ray altitude control system is an important equipment for deep space exploration and sample return mission, its main purpose is a low altitude measurement of the spacecraft based on Compton Effect at the moment when it lands on extraterrestrial celestial or sampling returns to the Earth land, and an ignition altitude correction of the spacecraft retrograde landing rocket at different landing speeds. This paper presents an ignition altitude correction method of the spacecraft at different landing speeds, based on the number of particles gamma ray reflected field gradient graded. Through the establishment of a theoretical model, its algorithm feasibility is proved by a mathematical derivation and verified by an experiment, and also the adaptability of the algorithm under different parameters is described. The method provides a certain value for landing control of the deep space exploration spacecraft landing the planet surface.

  12. RESEARCH ON THE KEY TECHNOLOGY OF LARGE SCALE MAPPING FROM LOW ALTITUDE PHOTOGRAMMETRY

    Directory of Open Access Journals (Sweden)

    W. Bo-Yi

    2016-06-01

    Full Text Available Based on the theoretic analysis of the accuracy in large scale photogrammetric mapping, some defects in traditional procedure were discussed. A set of key technologies dedicate to accuracy improvement in low altitude photogrammetry were analyzed in detail, namely the utilization of wide angle camera and low altitude flight, enhancement in image matching, predesigned layout of Ground Control Points (GCPs in field survey, optimization of adjustment model and improvement in map processing. Besides, a low altitude aerial unmanned airship system was established. Finally, successful implementation in 1:500 topographic mapping project in built-up areas of 30 counties in Shanxi Province proves the practicability and effectiveness of the proposed approaches.

  13. A Robust Photogrammetric Processing Method of Low-Altitude UAV Images

    Directory of Open Access Journals (Sweden)

    Mingyao Ai

    2015-02-01

    Full Text Available Low-altitude Unmanned Aerial Vehicles (UAV images which include distortion, illumination variance, and large rotation angles are facing multiple challenges of image orientation and image processing. In this paper, a robust and convenient photogrammetric approach is proposed for processing low-altitude UAV images, involving a strip management method to automatically build a standardized regional aerial triangle (AT network, a parallel inner orientation algorithm, a ground control points (GCPs predicting method, and an improved Scale Invariant Feature Transform (SIFT method to produce large number of evenly distributed reliable tie points for bundle adjustment (BA. A multi-view matching approach is improved to produce Digital Surface Models (DSM and Digital Orthophoto Maps (DOM for 3D visualization. Experimental results show that the proposed approach is robust and feasible for photogrammetric processing of low-altitude UAV images and 3D visualization of products.

  14. Investigating the auroral electrojets with low altitude polar orbiting satellites

    DEFF Research Database (Denmark)

    Moretto, T.; Olsen, Nils; Ritter, P.

    2002-01-01

    Three geomagnetic satellite missions currently provide high precision magnetic field measurements from low altitude polar orbiting spacecraft. We demonstrate how these data can be used to determine the intensity and location of the horizontal currents that flow in the ionosphere, predominantly...

  15. Low-Altitude Airbursts and the Impact Threat - Final LDRD Report.

    Energy Technology Data Exchange (ETDEWEB)

    Boslough, Mark B.; Crawford, David A.

    2007-12-01

    The purpose of this nine-week project was to advance the understanding of low-altitude airbursts by developing the means to model them at extremely high resolution in order to span the scales of entry physics as well as blast wave and plume formation. Small asteroid impacts on Earth are a recognized hazard, but the full nature of the threat is still not well understood. We used shock physics codes to discover emergent phenomena associated with low-altitude airbursts such as the Siberian Tunguska event of 1908 and the Egyptian glass-forming event 29 million years ago. The planetary defense community is beginning to recognize the significant threat from such airbursts. Low-altitude airbursts are the only class of impacts that have a significant probability of occurring within a planning time horizon. There is roughly a 10% chance of a megaton-scale low-altitude airburst event in the next decade.The first part of this LDRD final project report is a preprint of our proceedings paper associated with the plenary presentation at the Hypervelocity Impact Society 2007 Symposium in Williamsburg, Virginia (International Journal of Impact Engineering, in press). The paper summarizes discoveries associated with a series of 2D axially-symmetric CTH simulations. The second part of the report contains slides from an invited presentation at the American Geophysical Union Fall 2007 meeting in San Francisco. The presentation summarizes the results of a series of 3D oblique impact simulations of the 1908 Tunguska explosion. Because of the brevity of this late-start project, the 3D results have not yet been written up for a peer-reviewed publication. We anticipate the opportunity to eventually run simulations that include the actual topography at Tunguska, at which time these results will be published.3

  16. Simulation development of a forward sensor-enhanced low-altitude guidance system

    Science.gov (United States)

    Zelenka, Richard E.; Swenson, Harry N.; Dearing, Munro G.; Hardy, Gordon H.

    1993-01-01

    The requirement to operate aircraft at low-altitude near the terrain is common in the military community and essential for helicopters. The risk and crew workload in this flight regime is severe, with navigation, guidance, and obstacle avoidance demanding high attention. A guidance system relying on digitized terrain elevation maps has been developed that employs airborne navigation, mission requirements, aircraft performance limits, and radar altimeter returns to generate a valley-seeking, low-altitude trajectory between waypoints for display to the pilot. This system has been flight demonstrated to 150 ft above ground level altitude, and is primarily limited by the ability of the pilot to perform obstacle detection and avoidance. In this study, a wide field of view forward sensor has been modeled and incorporated in the guidance system for the purpose of relieving the pilot of the obstacle avoidance duty. The results of a piloted, motion-based simulation of this enhanced low-altitude guidance system is presented. Simulated flights to 50 ft altitude in the presence of obstacles were demonstrated while maintaining situational awareness and close tracking of the guidance trajectory.

  17. Develop a Model Component

    Science.gov (United States)

    Ensey, Tyler S.

    2013-01-01

    During my internship at NASA, I was a model developer for Ground Support Equipment (GSE). The purpose of a model developer is to develop and unit test model component libraries (fluid, electrical, gas, etc.). The models are designed to simulate software for GSE (Ground Special Power, Crew Access Arm, Cryo, Fire and Leak Detection System, Environmental Control System (ECS), etc. .) before they are implemented into hardware. These models support verifying local control and remote software for End-Item Software Under Test (SUT). The model simulates the physical behavior (function, state, limits and 110) of each end-item and it's dependencies as defined in the Subsystem Interface Table, Software Requirements & Design Specification (SRDS), Ground Integrated Schematic (GIS), and System Mechanical Schematic.(SMS). The software of each specific model component is simulated through MATLAB's Simulink program. The intensiv model development life cycle is a.s follows: Identify source documents; identify model scope; update schedule; preliminary design review; develop model requirements; update model.. scope; update schedule; detailed design review; create/modify library component; implement library components reference; implement subsystem components; develop a test script; run the test script; develop users guide; send model out for peer review; the model is sent out for verifictionlvalidation; if there is empirical data, a validation data package is generated; if there is not empirical data, a verification package is generated; the test results are then reviewed; and finally, the user. requests accreditation, and a statement of accreditation is prepared. Once each component model is reviewed and approved, they are intertwined together into one integrated model. This integrated model is then tested itself, through a test script and autotest, so that it can be concluded that all models work conjointly, for a single purpose. The component I was assigned, specifically, was a

  18. The contributions of high- and low altitude emission sources to the near ground concentrations of air pollutants

    Science.gov (United States)

    Đorđević, Dragana S.; Šolević, Tatjana M.

    2008-02-01

    The scale of transport through the atmosphere depends on the effective height of an emission source, the meteorological conditions and the physico-chemical characteristics of the pollutants. Atmospheric surface temperature inversions play a significant role in the problem of air pollution since their upper edge acts as a natural barrier to the vertical dispersion of pollutants. When the altitude of an emission source is lower than the edge of the boundary layer, the pollution remains below the upper edge and spreads by advection inside the lower layer towards the ground. However, if the altitude of the emission source is higher than the edge of the boundary layer, then the pollution spreads above the barrier. An analysis of a pollution episode during one month (August 2004) in an urban atmosphere of industrial city, using results of continuous monitoring of minute-by-minute fluctuations of the pollutants' concentrations, is presented. Region of a developed industrial town as a model was investigated. The investigated region is characterized by maximum number of surface temperature inversions during the nights in August and their furlough during the day time. With a combination of local meteorological information, that is the number of surface temperature inversions of the atmosphere, the results showed that the concentrations of pollutants originating from low altitude emission sources, e.g. organic pollutants, were higher at night. The near ground concentrations of SO 2, originating from high-(industrial stacks) and low altitude (traffic) sources, and the PM 10 originating from various sources i.e. from complex mechanisms of formation e.g. traffic emissions, SOA mechanisms and re-suspensions, were the same during the night and during the day. However, concentrations of NH 3 from high altitude sources (fertilizer plant) were higher during the day. Cluster Analysis and Principal Component Analysis showed associations of highest correlation between pollutants, which

  19. Imaging Mercury's polar deposits during MESSENGER's low-altitude campaign

    Science.gov (United States)

    Chabot, Nancy L.; Ernst, Carolyn M.; Paige, David A.; Nair, Hari; Denevi, Brett W.; Blewett, David T.; Murchie, Scott L.; Deutsch, Ariel N.; Head, James W.; Solomon, Sean C.

    2016-09-01

    Images obtained during the low-altitude campaign in the final year of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission provide the highest-spatial-resolution views of Mercury's polar deposits. Images for distinct areas of permanent shadow within 35 north polar craters were successfully captured during the campaign. All of these regions of permanent shadow were found to have low-reflectance surfaces with well-defined boundaries. Additionally, brightness variations across the deposits correlate with variations in the biannual maximum surface temperature across the permanently shadowed regions, supporting the conclusion that multiple volatile organic compounds are contained in Mercury's polar deposits, in addition to water ice. A recent large impact event or ongoing bombardment by micrometeoroids could deliver water as well as many volatile organic compounds to Mercury. Either scenario is consistent with the distinctive reflectance properties and well-defined boundaries of Mercury's polar deposits and the presence of volatiles in all available cold traps.

  20. Computer vision techniques for rotorcraft low altitude flight

    Science.gov (United States)

    Sridhar, Banavar

    1990-01-01

    Rotorcraft operating in high-threat environments fly close to the earth's surface to utilize surrounding terrain, vegetation, or manmade objects to minimize the risk of being detected by an enemy. Increasing levels of concealment are achieved by adopting different tactics during low-altitude flight. Rotorcraft employ three tactics during low-altitude flight: low-level, contour, and nap-of-the-earth (NOE). The key feature distinguishing the NOE mode from the other two modes is that the whole rotorcraft, including the main rotor, is below tree-top whenever possible. This leads to the use of lateral maneuvers for avoiding obstacles, which in fact constitutes the means for concealment. The piloting of the rotorcraft is at best a very demanding task and the pilot will need help from onboard automation tools in order to devote more time to mission-related activities. The development of an automation tool which has the potential to detect obstacles in the rotorcraft flight path, warn the crew, and interact with the guidance system to avoid detected obstacles, presents challenging problems. Research is described which applies techniques from computer vision to automation of rotorcraft navigtion. The effort emphasizes the development of a methodology for detecting the ranges to obstacles in the region of interest based on the maximum utilization of passive sensors. The range map derived from the obstacle-detection approach can be used as obstacle data for the obstacle avoidance in an automatic guidance system and as advisory display to the pilot. The lack of suitable flight imagery data presents a problem in the verification of concepts for obstacle detection. This problem is being addressed by the development of an adequate flight database and by preprocessing of currently available flight imagery. The presentation concludes with some comments on future work and how research in this area relates to the guidance of other autonomous vehicles.

  1. Developing a Model Component

    Science.gov (United States)

    Fields, Christina M.

    2013-01-01

    The Spaceport Command and Control System (SCCS) Simulation Computer Software Configuration Item (CSCI) is responsible for providing simulations to support test and verification of SCCS hardware and software. The Universal Coolant Transporter System (UCTS) was a Space Shuttle Orbiter support piece of the Ground Servicing Equipment (GSE). The initial purpose of the UCTS was to provide two support services to the Space Shuttle Orbiter immediately after landing at the Shuttle Landing Facility. The UCTS is designed with the capability of servicing future space vehicles; including all Space Station Requirements necessary for the MPLM Modules. The Simulation uses GSE Models to stand in for the actual systems to support testing of SCCS systems during their development. As an intern at Kennedy Space Center (KSC), my assignment was to develop a model component for the UCTS. I was given a fluid component (dryer) to model in Simulink. I completed training for UNIX and Simulink. The dryer is a Catch All replaceable core type filter-dryer. The filter-dryer provides maximum protection for the thermostatic expansion valve and solenoid valve from dirt that may be in the system. The filter-dryer also protects the valves from freezing up. I researched fluid dynamics to understand the function of my component. The filter-dryer was modeled by determining affects it has on the pressure and velocity of the system. I used Bernoulli's Equation to calculate the pressure and velocity differential through the dryer. I created my filter-dryer model in Simulink and wrote the test script to test the component. I completed component testing and captured test data. The finalized model was sent for peer review for any improvements. I participated in Simulation meetings and was involved in the subsystem design process and team collaborations. I gained valuable work experience and insight into a career path as an engineer.

  2. Aircraft Low Altitude Wind Shear Detection and Warning System.

    Science.gov (United States)

    Sinclair, Peter C.; Kuhn, Peter M.

    1991-01-01

    There is now considerable evidence to substantiate the causal relationship between low altitude wind shear (LAWS) and the recent increase in low-altitude aircraft accidents. The National Research Council has found that for the period 1964 to 1982, LAWS was involved in nearly all the weather-related air carrier fatalities. However, at present, there is no acceptable method, technique, or hardware system that provides the necessary safety margins, for spatial and timely detection of LAWS from an aircraft during the critical phases of landing and takeoff. The Federal Aviation Administration (FAA) has addressed this matter and supports the development of an airborne system for detecting hazardous LAWS with at least a one minute warning of the potential hazard to the pilot. One of the purposes of this paper is to show from some of our preliminary flight measurement research that a forward looking infrared radiometer (FLIR) system can be used to successfully detect the cool downdraft of downbursts [microbursts/macrobursts (MB)] and thunderstorm gust front outflows that are responsible for most of the LAWS events. The FLIR system provides a much greater safety margin for the pilot than that provided by reactive designs such as inertial-air speed systems that require the actual penetration of the MB before a pilot warning can be initiated. Our preliminary results indicate that an advanced airborne FLIR system could provide the pilot with remote indication of MB threat, location, movement, and predicted MB hazards along the flight path ahead of the aircraft.In a proof-of-concept experiment, we have flight tested a prototype FLIR system (nonscanning, fixed range) near and within Colorado MBs with excellent detectability. The results show that a minimum warning time of one-four minutes (5×10 km), depending on aircraft speed, is available to the pilot prior to a MB encounter. Analysis of the flight data with respect to a modified `hazard index' indicates the severe hazard

  3. Application of altitude control techniques for low altitude earth satellites

    Science.gov (United States)

    Nickerson, K. G.; Herder, R. W.; Glass, A. B.; Cooley, J. L.

    1977-01-01

    The applications sensors of many low altitude earth satellites designed for recording surface or atmospheric data require near zero orbital eccentricities for maximum usefulness. Coverage patterns and altitude profiles require specified values of orbit semimajor axis. Certain initial combinations of semimajor axis, eccentricity, and argument of perigee can produce a so called 'frozen orbit' and minimum altitude variation which enhances sensor coverage. This paper develops information on frozen orbits and minimum altitude variation for all inclinations, generalizing previous results. In the altitude regions where most of these satellites function (between 200 and 1000 kilometers) strong atmospheric drag effects influence the evolution of the initial orbits. Active orbital maneuver control techniques to correct evolution of orbit parameters while minimizing the frequency of maneuvers are presented. The paper presents the application of theoretical techniques for control of near frozen orbits and expands upon the methods useful for simultaneously targeting several inplane orbital parameters. The applications of these techniques are illustrated by performance results from the Atmosphere Explorer (AE-3 and -5) missions and in preflight maneuver analysis and plans for the Seasat Oceanographic Satellite.

  4. LOW ALTITUDE AIRSHIPS FOR SEAMLESS MOBILE COMMUNICATION IN AIR TRAVEL

    Directory of Open Access Journals (Sweden)

    Madhu D

    2014-11-01

    Full Text Available The Aviation Administration policy prohibits the use of mobile phones in Aircraft during transition for the reason it may harm their communication system due to Electromagnetic interference. In case the user wants to access cellular network at higher altitudes, base station access is a problem. Large number of channels are allocated to a single user moving at high speed by various Base Stations in the vicinity to service the request requiring more resources. Low Altitude Platforms (LAPs are provided in the form of Base stations in the Airships with antennas projected upwards which has direct link with the Ground Station. LAPs using LongEndurance Multi-Intelligence Vehicle (LEMVs equipped with an engine for mobility and stable positioning against rough winds are utilized. This paper proposes a system that allows the passengers to use their mobiles in Aircraft using LAPs as an intermediate system between Aircraft and Ground station. As the Aircraft is dynamic, it has to change its link frequently with the Airships, MANETs using AODV protocol is established in the prototype using NS2 to provide the service and the results are encouraging

  5. UAV Low Altitude Photogrammetry for Power Line Inspection

    Directory of Open Access Journals (Sweden)

    Yong Zhang

    2017-01-01

    Full Text Available When the distance between an obstacle and a power line is less than the discharge distance, a discharge arc can be generated, resulting in the interruption of power supplies. Therefore, regular safety inspections are necessary to ensure the safe operation of power grids. Tall vegetation and buildings are the key factors threatening the safe operation of extra high voltage transmission lines within a power line corridor. Manual or laser intensity direction and ranging (LiDAR based inspections are time consuming and expensive. To make safety inspections more efficient and flexible, a low-altitude unmanned aerial vehicle (UAV remote-sensing platform, equipped with an optical digital camera, was used to inspect power line corridors. We propose a semi-patch matching algorithm based on epipolar constraints, using both the correlation coefficient (CC and the shape of its curve to extract three dimensional (3D point clouds for a power line corridor. We use a stereo image pair from inter-strip to improve power line measurement accuracy by transforming the power line direction to an approximately perpendicular to epipolar line. The distance between the power lines and the 3D point cloud is taken as a criterion for locating obstacles within the power line corridor automatically. Experimental results show that our proposed method is a reliable, cost effective, and applicable way for practical power line inspection and can locate obstacles within the power line corridor with accuracy better than ±0.5 m.

  6. Capabilities of unmanned aircraft vehicles for low altitude weed detection

    Science.gov (United States)

    Pflanz, Michael; Nordmeyer, Henning

    2014-05-01

    Sustainable crop production and food security require a consumer and environmental safe plant protection. It is recently known, that precise weed monitoring approaches could help apply pesticides corresponding to field variability. In this regard the site-specific weed management may contribute to an application of herbicides with higher ecologically aware and economical savings. First attempts of precision agriculture date back to the 1980's. Since that time, remote sensing from satellites or manned aircrafts have been investigated and used in agricultural practice, but are currently inadequate for the separation of weeds in an early growth stage from cultivated plants. In contrast, low-cost image capturing at low altitude from unmanned aircraft vehicles (UAV) provides higher spatial resolution and almost real-time processing. Particularly, rotary-wing aircrafts are suitable for precise path or stationary flight. This minimises motion blur and provides better image overlapping for stitching and mapping procedures. Through improved image analyses and the recent increase in the availability of microcontrollers and powerful batteries for UAVs, it can be expected that the spatial mapping of weeds will be enhanced in the future. A six rotors microcopter was equipped with a modified RGB camera taking images from agricultural fields. The hexacopter operates within predefined pathways at adjusted altitudes (from 5 to 10 m) by using GPS navigation. Different scenarios of optical weed detection have been carried out regarding to variable altitude, image resolution, weed and crop growth stages. Our experiences showed high capabilities for site-specific weed control. Image analyses with regard to recognition of weed patches can be used to adapt herbicide application to varying weed occurrence across a field.

  7. The Eddy Experiment: accurate GNSS-R ocean altimetry from low altitude aircraft

    CERN Document Server

    Ruffini, G; Caparrini, M; Germain, O; Martin-Neira, M

    2004-01-01

    During the Eddy Experiment, two synchronous GPS receivers were flown at 1 km altitude to collect L1 signals and their reflections from the sea surface for assessment of altimetric precision and accuracy. Wind speed (U10) was around 10 m/s, and SWH up to 2 m. A geophysical parametric waveform model was used for retracking and estimation of the lapse between the direct and reflected signals with a 1-second precision of 3 m. The lapse was used to estimate the SSH along the track using a differential model. The RMS error of the 20 km averaged GNSS-R absolute altimetric solution with respect to Jason-1 SSH and a GPS buoy measurement was of 10 cm, with a 2 cm mean difference. Multipath and retracking parameter sensitivity due to the low altitude are suspected to have degraded accuracy. This result provides an important milestone on the road to a GNSS-R mesoscale altimetry space mission.

  8. Mercury's Crustal Magnetic Field from Low-Altitude Measurements by MESSENGER.

    Science.gov (United States)

    Johnson, C. L.; Phillips, R. J.; Purucker, M. E.; Anderson, B. J.; Byrne, P. K.; Denevi, B. W.; Fan, K. A.; Feinberg, J. M.; Hauck, S. A., II; Head, J. W., III; Korth, H.; James, P. B.; Mazarico, E.; Neumann, G. A.; Philpott, L. C.; Siegler, M. A.; Strauss, B. E.; Tsyganenko, N. A.; Solomon, S. C.

    2015-12-01

    Magnetized rocks can record the history of a planet's magnetic field, a key constraint for understanding interior evolution. From orbital vector magnetic field measurements of Mercury taken by the MESSENGER spacecraft at altitudes below 150 km, we have detected fields indicative of crustal magnetization. Fields from non-crustal sources, which dominate the observations even at low altitudes, were estimated and subtracted from the observations using both magnetospheric models and signal filtering. The resulting high-pass filtered fields have amplitudes of a few to 20 nT. The first low-altitude signals were detected over the Suisei Planitia region and were confirmed by upward continuation to be of crustal origin. At least some contribution from thermoremanent magnetization is required to account for these signals, and we infer a lower bound on the average age of magnetization of 3.7-3.9 Ga on the basis of correlation of crustal magnetic fields with volcanic units of that age range. Ancient field strengths that range from those similar to Mercury's present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury's crust derived from MESSENGER elemental composition data. Here, we extend these initial results with observations obtained at spacecraft altitudes below 60 km at all body-fixed longitudes from ~40°N to ~75°N. The strongest crustal fields occur in the region 120°E to 210°E, and weaker signals characterize the northern volcanic plains. We test the hypothesis that the longest-wavelength crustal field signals in this region reflect magnetization contrasts between the Caloris basin and the surrounding intercrater plains and circum-Caloris plains. We report the spatial distribution of observed crustal fields, together with magnetization models derived from them and the implications of these models, particularly for the depth distribution of sources compatible with the observations.

  9. Correction for reflected sky radiance in low-altitude coastal hyperspectral images.

    Science.gov (United States)

    Kim, Minsu; Park, Joong Yong; Kopilevich, Yuri; Tuell, Grady; Philpot, William

    2013-11-10

    Low-altitude coastal hyperspectral imagery is sensitive to reflections of sky radiance at the water surface. Even in the absence of sun glint, and for a calm water surface, the wide range of viewing angles may result in pronounced, low-frequency variations of the reflected sky radiance across the scan line depending on the solar position. The variation in reflected sky radiance can be obscured by strong high-spatial-frequency sun glint and at high altitude by path radiance. However, at low altitudes, the low-spatial-frequency sky radiance effect is frequently significant and is not removed effectively by the typical corrections for sun glint. The reflected sky radiance from the water surface observed by a low-altitude sensor can be modeled in the first approximation as the sum of multiple-scattered Rayleigh path radiance and the single-scattered direct-solar-beam radiance by the aerosol in the lower atmosphere. The path radiance from zenith to the half field of view (FOV) of a typical airborne spectroradiometer has relatively minimal variation and its reflected radiance to detector array results in a flat base. Therefore the along-track variation is mostly contributed by the forward single-scattered solar-beam radiance. The scattered solar-beam radiances arrive at the water surface with different incident angles. Thus the reflected radiance received at the detector array corresponds to a certain scattering angle, and its variation is most effectively parameterized using the downward scattering angle (DSA) of the solar beam. Computation of the DSA must account for the roll, pitch, and heading of the platform and the viewing geometry of the sensor along with the solar ephemeris. Once the DSA image is calculated, the near-infrared (NIR) radiance from selected water scan lines are compared, and a relationship between DSA and NIR radiance is derived. We then apply the relationship to the entire DSA image to create an NIR reference image. Using the NIR reference image

  10. Low altitude high speed cargo parachute system development: A status report

    Energy Technology Data Exchange (ETDEWEB)

    Sundberg, W.D.; Alsbrooks, T.H.; Ronquillo, K.L. (Sandia National Labs., Albuquerque, NM (USA)); Sadeck, J.E.; Lee, C.K. (Army Natick Research, Development and Engineering Center, MA (USA))

    1991-01-01

    A Low Altitude High Speed Cargo (LAHSC) parachute is being developed for deployment at velocities up to 250 knots at 300 ft altitude. The LAHSC parachute will decelerate and turnover a load to a 40 to 60 ft/sec vertical velocity at first vertical at approximately 30 ft AGL. The acceleration limit is 5 g's. Main chute cargo extraction will be necessary. A single parachute will be utilized for a 7500 lb load, and clusters will be used for larger loads. The 64-gore, 70-ft-dia parachute has a ring-slot/solid construction with a flare at the skirt to aid the inflation. This paper describes the parachute, the design process and testing to date. Model parachutes have been tested in wind tunnels and in free flight. A single full-scale parachute has been tested at low speeds with conventional load extraction, and with a vertical trajectory at deployment. 5 refs., 18 figs., 3 tabs.

  11. Easy-to-Use UAV Ground Station Software for Low-Altitude Civil Operations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design and develop easy-to-use Ground Control Station (GCS) software for low-altitude civil Unmanned Aerial Vehicle (UAV) operations. The GCS software...

  12. Precision Agriculture: Using Low-Cost Systems to Acquire Low-Altitude Images.

    Science.gov (United States)

    Ponti, Moacir; Chaves, Arthur A; Jorge, Fabio R; Costa, Gabriel B P; Colturato, Adimara; Branco, Kalinka R L J C

    2016-01-01

    Low cost remote sensing imagery has the potential to make precision farming feasible in developing countries. In this article, the authors describe image acquisition from eucalyptus, bean, and sugarcane crops acquired by low-cost and low-altitude systems. They use different approaches to handle low-altitude images in both the RGB and NIR (near-infrared) bands to estimate and quantify plantation areas.

  13. Compositae Plants Differed in Leaf Cuticular Waxes between High and Low Altitudes.

    Science.gov (United States)

    Guo, Na; Gao, Jianhua; He, Yuji; Guo, Yanjun

    2016-06-01

    We sampled eight Compositae species at high altitude (3482 m) and seven species at low altitude (220 m), analyzed the chemical compositions and contents of leaf cuticular wax, and calculated the values of average chain length (ACL), carbon preference index (CPI), dispersion (d), dispersion/weighted mean chain length (d/N), and C31 /(C31  + C29 ) (Norm31). The amounts of total wax and compositions were significantly higher at high altitude than at low altitude, except for primary alcohol, secondary alcohol, and ketone. The main n-alkanes in most samples were C31 , C29 , and C33 . Low altitude had more C31 and C33 , whereas more C29 occurred at high altitude. The ACL, CPI, d, d/N, and Norma 31 were higher at low altitude than at high altitude. The fatty acid and primary alcohol at low altitude contained more C26 homologous than at high altitude. More short-chain primary alcohols were observed at high altitude. At low altitude, the primary alcohol gave on average the largest amount, while it was n-alkane at high altitude. These results indicated that the variations of leaf cuticular waxes benefited Compositae plants to adapt to various environmental stresses and enlarge their distribution.

  14. Component Composition Using Feature Models

    DEFF Research Database (Denmark)

    Eichberg, Michael; Klose, Karl; Mitschke, Ralf;

    2010-01-01

    In general, components provide and require services and two components are bound if the first component provides a service required by the second component. However, certain variability in services - w.r.t. how and which functionality is provided or required - cannot be described using standard...... interface description languages. If this variability is relevant when selecting a matching component then human interaction is required to decide which components can be bound. We propose to use feature models for making this variability explicit and (re-)enabling automatic component binding. In our...... approach, feature models are one part of service specifications. This enables to declaratively specify which service variant is provided by a component. By referring to a service's variation points, a component that requires a specific service can list the requirements on the desired variant. Using...

  15. Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic

    Directory of Open Access Journals (Sweden)

    E. Real

    2008-12-01

    Full Text Available The photochemical evolution of an anthropogenic plume from the New-York/Boston region during its transport at low altitudes over the North Atlantic to the European west coast has been studied using a Lagrangian framework. This plume, originally strongly polluted, was sampled by research aircraft just off the North American east coast on 3 successive days, and then 3 days downwind off the west coast of Ireland where another aircraft re-sampled a weakly polluted plume. Changes in trace gas concentrations during transport are reproduced using a photochemical trajectory model including deposition and mixing effects. Chemical and wet deposition processing dominated the evolution of all pollutants in the plume. The mean net photochemical O3 production is estimated to be −5 ppbv/day leading to low O3 by the time the plume reached Europe. Model runs with no wet deposition of HNO3 predicted much lower average net destruction of −1 ppbv/day O3, arising from increased levels of NOx via photolysis of HNO3. This indicates that wet deposition of HNO3 is indirectly responsible for 80% of the net destruction of ozone during plume transport. If the plume had not encountered precipitation, it would have reached Europe with O3 concentrations of up to 80 to 90 ppbv and CO between 120 and 140 ppbv. Photochemical destruction also played a more important role than mixing in the evolution of plume CO due to high levels of O3 and water vapour showing that CO cannot always be used as a tracer for polluted air masses, especially in plumes transported at low altitudes. The results also show that, in this case, an increase in O3/CO slopes can be attributed to photochemical destruction of CO and not to photochemical O3 production as is often assumed.

  16. Measuring the seeds of ion outflow: Auroral sounding rocket observations of low-altitude ion heating and circulation

    Science.gov (United States)

    Fernandes, P. A.; Lynch, K. A.; Zettergren, M.; Hampton, D. L.; Bekkeng, T. A.; Cohen, I. J.; Conde, M.; Fisher, L. E.; Horak, P.; Lessard, M. R.; Miceli, R. J.; Michell, R. G.; Moen, J.; Powell, S. P.

    2016-02-01

    We present an analysis of in situ measurements from the MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) nightside auroral sounding rocket with comparisons to a multifluid ionospheric model. MICA made observations at altitudes below 325 km of the thermal ion kinetic particle distributions that are the origins of ion outflow. Late flight, in the vicinity of an auroral arc, we observe frictional processes controlling the ion temperature. Upflow of these cold ions is attributed to either the ambipolar field resulting from the heated electrons or possibly to ion-neutral collisions. We measure E→×B→ convection away from the arc (poleward) and downflows of hundreds of m s-1 poleward of this arc, indicating small-scale low-altitude plasma circulation. In the early flight we observe DC electromagnetic Poynting flux and associated ELF wave activity influencing the thermal ion temperature in regions of Alfvénic aurora. We observe enhanced, anisotropic ion temperatures which we conjecture are caused by transverse heating by wave-particle interactions (WPI) even at these low altitudes. Throughout this region we observe several hundred m s-1 upflow of the bulk thermal ions colocated with WPI; however, the mirror force is negligible at these low energies; thus, the upflow is attributed to ambipolar fields (or possibly neutral upwelling drivers). The low-altitude MICA observations serve to inform future ionospheric modeling and simulations of (a) the need to consider the effects of heating by WPI at altitudes lower than previously considered viable and (b) the occurrence of structured and localized upflows/downflows below where higher-altitude heating rocesses are expected.

  17. Component Breakout Computer Model

    Science.gov (United States)

    1987-04-29

    Weapon Systems: A Policy Analysis." The Rand Graduate Institute. November 1983. Boger . D. "Statistical Models for Estimating Overhead Costs." M. S...SQUARE SCREEN PROGRAM BO DLS 70 LOCATE 3,5 100 PRINT " I I I I I I I I I I I I I I t I I I t I I i iiitiii I I I I i t I i 110 LOCATE 4,5 I 20...GOTO 4620 4610 REM ***********«««*«««**#«***********#******»,*###!^5|[^,„<c#,5|c„ dl -r C^M EED SUPPORT .c.50 REM A6(6)...N0 OF EMPLOYEES 4660 IF

  18. Monitoring beach evolution using low-altitude aerial photogrammetry and UAV drones

    Science.gov (United States)

    Rovere, Alessio; Casella, Elisa; Vacchi, Matteo; Mucerino, Luigi; Pedroncini, Andrea; Ferrari, Marco; Firpo, Marco

    2014-05-01

    Beach monitoring is essential in order to understand the mechanisms of evolution of soft coasts, and the rates of erosion. Traditional beach monitoring techniques involve topographic and bathymetric surveys of the beach, and/or aerial photos repeated in time and compared through geographical information systems. A major problem of this kind of approach is the high economic cost. This often leads to increase the time lag between successive monitoring campaigns to reduce survey costs, with the consequence of fragmenting the information available for coastal zone management. MIRAMar is a project funded by Regione Liguria through the PO CRO European Social Fund, and has two main objectives: i) to study and develop an innovative technique, relatively low-cost, to monitor the evolution of the shoreline using low-altitude Unmanned Aerial Vehicle (UAV) photogrammetry; ii) to study the impact of different type of storm events on a vulnerable coastal tract subject to coastal erosion using also the data collected by the UAV instrument. To achieve these aims we use a drone with its hardware and software suit, traditional survey techniques (bathymetric surveys, topographic GPS surveys and GIS techniques) and we implement a numerical modeling chain (coupling hydrodynamic, wave and sand transport modules) in order to study the impact of different type of storm events on a vulnerable coastal tract subject to coastal erosion.

  19. Reconstructing Ion Spectra from Low-Altitude ENAs: Moderate to Large Storms.

    Science.gov (United States)

    LLera, K.; Goldstein, J.; McComas, D. J.; Valek, P. W.

    2015-12-01

    Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) Energetic neutral atom (ENA) imagers regularly observe Low-altitude Emission (LAE) intensifications during geomagnetic storm intervals. Since LAEs are produced by the interaction between ions and the near-Earth exosphere (altitudes ~200-800 km), they are a global signature of how the ring current decays in response to solar wind conditions. In this "optically thick" region, an ENA readily becomes reionized, and an ion is readily neutralized. Therefore, emerging ENAs that contribute to the LAE signal (detectable several RE away) have undergone multiple charge exchange and electron stripping interactions. Accounting for the ~36 eV energy loss per interaction, we developed a model to quantify the total energy lost by emergent LAEs. The analytical tool is applied to an ensemble of moderate to large storms (including the recent 17 March and 23 June storms in 2015) to reconstruct the parent ion spectra from TWINS ENA images. We examine the ion spectra energy characteristics among the various storm events.

  20. Differences in Hematological Traits between High- and Low-Altitude Lizards (Genus Phrynocephalus).

    Science.gov (United States)

    Lu, Songsong; Xin, Ying; Tang, Xiaolong; Yue, Feng; Wang, Huihui; Bai, Yucheng; Niu, Yonggang; Chen, Qiang

    2015-01-01

    Phrynocephalus erythrurus (Lacertilia: Agamidae) is considered to be the highest living reptile in the world (about 4500-5000 m above sea level), whereas Phrynocephalus przewalskii inhabits low altitudes (about 1000-1500 m above sea level). Here, we report the differences in hematological traits between these two different Phrynocephalus species. Compared with P. przewalskii, the results indicated that P. erythrurus own higher oxygen carrying capacity by increasing red blood cell count (RBC), hemoglobin concentration ([Hb]) and hematocrit (Hct) and these elevations could promote oxygen carrying capacity without disadvantage of high viscosity. The lower partial pressure of oxygen in arterial blood (PaO2) of P. erythrurus did not cause the secondary alkalosis, which may be attributed to an efficient pulmonary system for oxygen (O2) loading. The elevated blood-O2 affinity in P. erythrurus may be achieved by increasing intrinsic O2 affinity of isoHbs and balancing the independent effects of potential heterotropic ligands. We detected one α-globin gene and three β-globin genes with 1 and 33 amino acid substitutions between these two species, respectively. Molecular dynamics simulation results showed that amino acids substitutions in β-globin chains could lead to the elimination of hydrogen bonds in T-state Hb models of P. erythrurus. Based on the present data, we suggest that P. erythrurus have evolved an efficient oxygen transport system under the unremitting hypobaric hypoxia.

  1. Differences in Hematological Traits between High- and Low-Altitude Lizards (Genus Phrynocephalus.

    Directory of Open Access Journals (Sweden)

    Songsong Lu

    Full Text Available Phrynocephalus erythrurus (Lacertilia: Agamidae is considered to be the highest living reptile in the world (about 4500-5000 m above sea level, whereas Phrynocephalus przewalskii inhabits low altitudes (about 1000-1500 m above sea level. Here, we report the differences in hematological traits between these two different Phrynocephalus species. Compared with P. przewalskii, the results indicated that P. erythrurus own higher oxygen carrying capacity by increasing red blood cell count (RBC, hemoglobin concentration ([Hb] and hematocrit (Hct and these elevations could promote oxygen carrying capacity without disadvantage of high viscosity. The lower partial pressure of oxygen in arterial blood (PaO2 of P. erythrurus did not cause the secondary alkalosis, which may be attributed to an efficient pulmonary system for oxygen (O2 loading. The elevated blood-O2 affinity in P. erythrurus may be achieved by increasing intrinsic O2 affinity of isoHbs and balancing the independent effects of potential heterotropic ligands. We detected one α-globin gene and three β-globin genes with 1 and 33 amino acid substitutions between these two species, respectively. Molecular dynamics simulation results showed that amino acids substitutions in β-globin chains could lead to the elimination of hydrogen bonds in T-state Hb models of P. erythrurus. Based on the present data, we suggest that P. erythrurus have evolved an efficient oxygen transport system under the unremitting hypobaric hypoxia.

  2. Novel Approach for Estimating Nitrogen Content in Paddy Fields Using Low Altitude Remote Sensing System

    Science.gov (United States)

    Saberioon, M. M.; Gholizadeh, A.

    2016-06-01

    Concerns over the use of nitrogen have been increasing due to the high cost of fertilizers and environmental pollutions caused by excess nitrogen application in agricultural fields. Several methods are available to assess the amount of nitrogen in crops, however, they are expensive, time-consuming, inaccurate, and/or require specialists to operate the tools. Researcher recently suggested remote sensing and specifically Low Altitude Remote Sensing (LARS) system of chlorophyll content in crop canopies as a low-cost alternative to estimate plant nitrogen status. The main objective of this study was to develop and test a new Vegetation Index (VI) to determine the status of nitrogen and chlorophyll content in rice leaf by analysing and considering all Visible (Vis) bands. Besides, capability of introduced VI has compared with all known VIs in both Vis and Near Infrared (NIR) bands in canopy scale. To develop the VI, images from 6-pannel leaf colour chart were acquired using Basler Scout scA640-70fc under light-emitting diode lighting, in which principal component analysis was used to retain the lower order principal component to develop a new index called IPCA. A conventional digital camera mounted to an Unmanned Aerial Vehicle (UAV) was also used to acquire images over the rice canopy in Vis bands. Simultaneously, Tetracam agriculture digital camera was employed to acquire rice canopy image in Vis-NIR bands. The results indicated that the proposed index at canopy (r = 0.78) scale could be used as a sensor to determine the status of chlorophyll content consequently for monitoring nitrogen in rice plant through different growth stages. Moreover, results confirmed that a lowcost LARS system would be suited for high spatial and temporal resolution images and data analysis for proper assessment of key nutrients in crop farming in a fast, inexpensive and non-destructive way.

  3. Development and application of procedures to evaluate air quality and visibility impacts of low-altitude flying operations

    Energy Technology Data Exchange (ETDEWEB)

    Liebsch, E.J.

    1990-08-01

    This report describes the development and application of procedures to evaluate the effects of low-altitude aircraft flights on air quality and visibility. The work summarized in this report was undertaken as part of the larger task of assessing the various potential environmental impacts associated with low-altitude military airspaces. Accomplishing the air quality/visibility analysis for the GEIS included (1) development and application of an integrated air quality model and aircraft emissions database specifically for Military Training Route (MTR) or similar flight operations, (2) selection and application of an existing air quality model to analyze the more widespread and less concentrated aircraft emissions from military Operations Areas (MOAs) and Restricted Areas (RAs), and (3) development and application of procedures to assess impacts of aircraft emissions on visibility. Existing air quality models were considered to be inadequate for predicting ground-level concentrations of pollutants emitted by aircraft along MTRs; therefore, the Single-Aircraft Instantaneous Line Source (SAILS) and Multiple-Aircraft Instantaneous Line Source (MAILS) models were developed to estimate potential impacts along MTRs. Furthermore, a protocol was developed and then applied in the field to determine the degree of visibility impairment caused by aircraft engine exhaust plumes. 19 refs., 2 figs., 3 tabs.

  4. Unmanned aerial vehicle: A unique platform for low-altitude remote sensing for crop management

    Science.gov (United States)

    Unmanned aerial vehicles (UAV) provide a unique platform for remote sensing to monitor crop fields that complements remote sensing from satellite, aircraft and ground-based platforms. The UAV-based remote sensing is versatile at ultra-low altitude to be able to provide an ultra-high-resolution imag...

  5. On assumption in low-altitude investigation of dayside magnetospheric phenomena

    Science.gov (United States)

    Koskinen, H. E. J.

    In the physics of large-scale phenomena in complicated media, such as space plasmas, the chain of reasoning from the fundamental physics to conceptual models is a long and winding road, requiring much physical insight and reliance on various assumptions and approximations. The low-altitude investigation of dayside phenomena provides numerous examples of problems arising from the necessity to make strong assumptions. In this paper we discuss some important assumptions that are either unavoidable or at least widely used. Two examples are the concepts of frozen-in field lines and convection velocity. Instead of asking what violates the frozen-in condition, it is quite legitimate to ask what freezes the plasma and the magnetic field in the first place. Another important complex of problems are the limitations introduced by a two-dimensional approach or linearization of equations. Although modern research is more and more moving toward three-dimensional and time-dependent models, limitations in computing power often make a two-dimensional approach tempting. In a similar way, linearization makes equations analytically tractable. Finally, a very central question is the mapping. In the first approximation, the entire dayside magnetopause maps down to the ionosphere through the dayside cusp region. From the mapping viewpoint, the cusp is one of the most difficult regions and assumptions needed to perform the mapping in practice must be considered with the greatest possible care. We can never avoid assumptions but we must always make them clear to ourselves and also to the readers of our papers.

  6. Influence of Ionization Degrees on the Evolutions of Charged Particles in Atmospheric Plasma at Low Altitude

    Institute of Scientific and Technical Information of China (English)

    PANG Xuexia; DENG Zechao; JIA Pengying; LIANG Weihua; LI Xia

    2012-01-01

    A zero-dimensional model which includes 56 species of reactants and 427 reactions is used to study the behavior of charged particles in atmospheric plasmas with different ionization degrees at low altitude (near 0 km). The constant coefficient nonlinear equations are solved by using the Quasi-steady-state approximation method. The electron lifetimes are obtained for afterglow plasma with different initial values, and the temporal evolutions of the main charged species are presented, which are dominant in reaction processes. The results show that the electron number density decays quickly. The lifetimes of electrons are shortened by about two orders with increasing ionization degree. Electrons then attach to neutral particles and produce negative ions. When the initial electron densities are in the range of 10l~ ~ 1014 cm-3, the negative ions have sufficiently high densities and long lifetimes for air purification, disinfection and sterilization. Electrons, O(2,-), O(4,-) CO(4,-) and CO(3,-) are the dominant negative species when the initial electron density neo ≤ 1013 cm^(-3), and only electrons and CO3 are left when neo 〉 1015 cm^(-3). N(+,2), N+ and O(+,2) are dominant in the positive charges for any ionization degree. Other positive species, such as 0(+,4), N(+,3), NO(+,2), NO(+,2), Ar(+,2) and H3O+. H2O, are dominant only for a certain ionization degree and in a certain period.

  7. The cyclical component factor model

    DEFF Research Database (Denmark)

    Dahl, Christian Møller; Hansen, Henrik; Smidt, John

    Forecasting using factor models based on large data sets have received ample attention due to the models' ability to increase forecast accuracy with respect to a range of key macroeconomic variables in the US and the UK. However, forecasts based on such factor models do not uniformly outperform...... the simple autoregressive model when using data from other countries. In this paper we propose to estimate the factors based on the pure cyclical components of the series entering the large data set. Monte Carlo evidence and an empirical illustration using Danish data shows that this procedure can indeed...

  8. Low altitude aerial photogrammetry application to braided river systems. Example of the Buech River, Alps, France.

    Science.gov (United States)

    Jules Fleury, Thomas; Pothin, Virginie; Vella, Claude; Dussouillez, Philippe; Izem, Abdelkoddouss

    2015-04-01

    Low-altitude aerial photogrammetry offers new opportunities for geomorphology and other fields requiring very high-resolution topographic data. It combines the advantages of the reproducibility of GPS topographic surveys with the high accuracy of LIDAR, but at relatively low-cost, easy-to-deploy and with the synaptic advantage of remote sensing. In order to evaluate the potential of photogrammetry on river systems and to assess river-bed changes and erosion-accretion processes, we conducted several surveys over the period of one year on the Buech river, a gravel-bed braided river located in the French Southern Alps. The study area is located directly upstream of a gravel pit and there is an interest in evaluating its effects on the riverbed. Our field protocol was comprised of vertical aerial photographs taken from a microlight aircraft flying approximately 300 ft above the ground. The equipment used was a full-frame DSLR with a wide angle lense, synchronised with a DGPS onboard. Fourty 40cm wide targets were placed on the ground and georeferenced by RTK DGPS with an accuracy of 2cm. In addition, close to one thousand Ground Control Points (GCPs) were measured within the different types of ground surfaces (vegetated, water, gravels) in order to assess the Digital Terrain Model (DTM) accuracy. We operated the production of the 3D model and its derived products: Digital Surface Model (DSM) and orthophotography, with user-friendly Agisoft (c) Photoscan Professional software. The processing of several hundred pictures with 2.5 cm ground resolution resulted in a DSM with a resolution of 10 cm and a vertical accuracy within 5 cm. As is expected, accuracy was best on bare bars and decreased with increasing vegetation density. To complement the DSM in the wetted channels, we used the orthophotos to establish a relationship between water color and flow depth using statistical multivariate regressions. Merging the bathymetric model and the DSM produced a DTM with a vertical

  9. Efficient content-based low-altitude images correlated network and strips reconstruction

    Science.gov (United States)

    He, Haiqing; You, Qi; Chen, Xiaoyong

    2017-01-01

    The manual intervention method is widely used to reconstruct strips for further aerial triangulation in low-altitude photogrammetry. Clearly the method for fully automatic photogrammetric data processing is not an expected way. In this paper, we explore a content-based approach without manual intervention or external information for strips reconstruction. Feature descriptors in the local spatial patterns are extracted by SIFT to construct vocabulary tree, in which these features are encoded in terms of TF-IDF numerical statistical algorithm to generate new representation for each low-altitude image. Then images correlated network is reconstructed by similarity measure, image matching and geometric graph theory. Finally, strips are reconstructed automatically by tracing straight lines and growing adjacent images gradually. Experimental results show that the proposed approach is highly effective in automatically rearranging strips of lowaltitude images and can provide rough relative orientation for further aerial triangulation.

  10. Upper atomosphere and Thermal control of the Super Low Altitude Test Satellite

    OpenAIRE

    2013-01-01

    The Super Low Altitude Test Satellite (SLATS) is an engineering test satellite currently under development in JAXA in an attempt to open a new frontier of space utilization on extremely low earth orbits. The altitude of SLATS orbit is around200km altitude. In this altitude, rarefied aerodynamics and high-density atomic oxygen effect on the thermal design of SLATS. The thermal control of SLATS was introduced in this paper. And, the equilibrium temperature on the bumper of SLATS was estimated w...

  11. Oblique low-altitude image matching using robust perspective invariant features

    Science.gov (United States)

    He, Haiqing; Du, Jing; Chen, Xiaoyong; Wang, Yuqian

    2017-01-01

    Compared with vertical photogrammtry, oblique photogrammetry is radically different for images acquired from sensor with big yaw, pitch, and roll angles. Image matching is a vital step and core problem of oblique low-altitude photogrammetric process. Among the most popular oblique images matching methods are currently SIFT/ASIFT and many affine invariant feature-based approaches, which are mainly used in computer vision, while these methods are unsuitable for requiring evenly distributed corresponding points and high efficiency simultaneously in oblique photogrammetry. In this paper, we present an oblique low-altitude images matching approach using robust perspective invariant features. Firstly, the homography matrix is estimated by a few corresponding points obtained from top pyramid images matching in several projective simulation. Then images matching are implemented by sub-pixel Harris corners and descriptors after shape perspective transforming on the basis of homography matrix. Finally, the error or gross error matched points are excluded by epipolar geometry, RANSAC algorithm and back projection constraint. Experimental results show that the proposed approach can achieve more excellent performances in oblique low-altitude images matching than the common methods, including SIFT and SURF. And the proposed approach can significantly improve the computational efficiency compared with ASIFT and Affine-SURF.

  12. Analysis of the hazardous low-altitude snowfall, 8th March 2010, in Catalonia

    Science.gov (United States)

    Aran, M.; Rigo, T.; Bech, J.; Brucet, C.; Vilaclara, E.

    2010-09-01

    During winter season snow precipitation is quite frequent in the Pyrenees (north-east of the Iberian Peninsula). On average the total amount of fresh snow at 2200 metres is of 250 cm. However, important snow episodes at low latitudes are unlikely. From 1947 to 2009, 16 significant snow episodes took place in the Barcelona and 18 in Girona areas. On 8th March 2010, a severe wet snow event had a high social impact on these regions. One of the most remarkable features of this episode was the type of precipitation (wet snow) and the large amount of precipitation combined with strong wind gust that caused the collapse of electricity pylons and tree forests. The damage was very important in the north-eastern part and the regional government approved funds of 21.4 million € to reduce the impact caused by this event. Although diagnosis of other low altitude snowfall events in Catalonia has been done previously, the analysis of this event can contribute to characterise a little bit better these snow episodes. In this study, we will present the synoptic framework characterised by the presence of a deep low in the north-east of Catalonia and moving through Ebro valley to the Catalan coast. To do this we will use ECMWF reanalyses and Meteosat images. The main features to predict this snow event and the critical point were the total amount of precipitation and snow level forecasted by mesoscale models (MM5, WRF). The model outputs for precipitation, temperature and wind will be compared with automatic weather, radar and radiosounding data. The snow level and the type of precipitation are compared with the information received from spotters. The main storm was characterised by moderate vertical development with tops of 8 km (4 km were the average height during the initial and final phase of the event). Also, lightning activity was observed, 310 intra-cloud and 128 cloud-to-ground. The type of precipitation at a specific location in the eastern zone temporally changed because

  13. Component-specific modeling. [jet engine hot section components

    Science.gov (United States)

    Mcknight, R. L.; Maffeo, R. J.; Tipton, M. T.; Weber, G.

    1992-01-01

    Accomplishments are described for a 3 year program to develop methodology for component-specific modeling of aircraft hot section components (turbine blades, turbine vanes, and burner liners). These accomplishments include: (1) engine thermodynamic and mission models, (2) geometry model generators, (3) remeshing, (4) specialty three-dimensional inelastic structural analysis, (5) computationally efficient solvers, (6) adaptive solution strategies, (7) engine performance parameters/component response variables decomposition and synthesis, (8) integrated software architecture and development, and (9) validation cases for software developed.

  14. Unmanned Aircraft Systems Traffic Management (UTM) Safely Enabling UAS Operations in Low-Altitude Airspace

    Science.gov (United States)

    Kopardekar, Parimal H.

    2016-01-01

    Unmanned Aircraft System (UAS) Traffic Management (UTM) Enabling Civilian Low-Altitude Airspace and Unmanned Aircraft System Operations What is the problem? Many beneficial civilian applications of UAS have been proposed, from goods delivery and infrastructure surveillance, to search and rescue, and agricultural monitoring. Currently, there is no established infrastructure to enable and safely manage the widespread use of low-altitude airspace and UAS operations, regardless of the type of UAS. A UAS traffic management (UTM) system for low-altitude airspace may be needed, perhaps leveraging concepts from the system of roads, lanes, stop signs, rules and lights that govern vehicles on the ground today, whether the vehicles are driven by humans or are automated. What system technologies is NASA exploring? Building on its legacy of work in air traffic management for crewed aircraft, NASA is researching prototype technologies for a UAS Traffic Management (UTM) system that could develop airspace integration requirements for enabling safe, efficient low-altitude operations. While incorporating lessons learned from the today's well-established air traffic management system, which was a response that grew out of a mid-air collision over the Grand Canyon in the early days of commercial aviation, the UTM system would enable safe and efficient low-altitude airspace operations by providing services such as airspace design, corridors, dynamic geofencing, severe weather and wind avoidance, congestion management, terrain avoidance, route planning and re-routing, separation management, sequencing and spacing, and contingency management. One of the attributes of the UTM system is that it would not require human operators to monitor every vehicle continuously. The system could provide to human managers the data to make strategic decisions related to initiation, continuation, and termination of airspace operations. This approach would ensure that only authenticated UAS could operate

  15. Drag Coefficients of Low Altitude Stationary Flight Test Airship Estimated from Flight Tests

    Science.gov (United States)

    Okuyama, Masahiro; Matsumoto, Takashi

    Flight tests were carried out to obtain aerodynamic characteristics of the low altitude stationary flight test airship. The deceleration test method was used in a flight experiment to obtain the drag coefficient. Combining with the deceleration test result, the minimum drag coefficient was acquired by equating a thrust force with the corresponding drag force at the steady level flight. As a result, 0.044±0.002 were obtained on the minimum drag coefficient of the airship. Modifications of the deceleration test data analysis are proposed to be applicable to test data obtained under non-zero attack angle etc. in the paper.

  16. Unmanned Aircraft Systems Traffic Management (UTM) Safely Enabling UAS Operations in Low-Altitude Airspace

    Science.gov (United States)

    Kopardekar, Parimal H.

    2017-01-01

    Conduct research, development and testing to identify airspace operations requirements to enable large-scale visual and beyond visual line of sight UAS operations in the low-altitude airspace. Use build-a-little-test-a-little strategy remote areas to urban areas Low density: No traffic management required but understanding of airspace constraints. Cooperative traffic management: Understanding of airspace constraints and other operations. Manned and unmanned traffic management: Scalable and heterogeneous operations. UTM construct consistent with FAAs risk-based strategy. UTM research platform is used for simulations and tests. UTM offers path towards scalability

  17. Massive photometry of low-altitude artificial satellites on Mini-Mega-TORTORA

    Science.gov (United States)

    Karpov, S.; Katkova, E.; Beskin, G.; Biryukov, A.; Bondar, S.; Davydov, E.; Ivanov, E.; Perkov, A.; Sasyuk, V.

    2016-12-01

    The nine-channel Mini-Mega-TORTORA (MMT-9) optical wide-field monitoring system with high temporal resolution system is in operation since June 2014. The system has 0.1 s temporal resolution and effective detection limit around 10 mag (calibrated to V filter) for fast-moving objects on this timescale. In addition to its primary scientific operation, the system detects 200-500 tracks of satellites every night, both on low-altitude and high ellipticity orbits. Using these data we created and support the public database of photometric characteristics for these satellites, available online.

  18. Safely Enabling Civilian Unmanned Aerial System (UAS) Operations in Low-Altitude Airspace by Unmanned Aerial System Traffic Management (UTM)

    Science.gov (United States)

    Kopardekar, Parimal Hemchandra

    2015-01-01

    Many UAS will operate at lower altitude (Class G, below 2000 feet). There is an urgent need for a system for civilian low-altitude airspace and UAS operations. Stakeholders want to work with NASA to enable safe operations.

  19. Impacts of more frequent droughts on a relict low-altitude Pinus uncinata stand in the French Alps

    OpenAIRE

    2015-01-01

    Cold microclimatic conditions provide exceptional microhabitats to Pinus uncinata stands occurring at abnormally low altitudes in seven paleorefugia of the northern French Alps. Here, P. uncinata is located at the lower bounds of its ecological limits and therefore expected to provide a sensitive indicator of climate change processes. We used dendrochronological analysis to study the growth patterns of closely spaced chronologies across an elevational transect and compare a relict low-altitud...

  20. Integration of radar altimeter, precision navigation, and digital terrain data for low-altitude flight

    Science.gov (United States)

    Zelenka, Richard E.

    1992-01-01

    Avionic systems that depend on digitized terrain elevation data for guidance generation or navigational reference require accurate absolute and relative distance measurements to the terrain, especially as they approach lower altitudes. This is particularly exacting in low-altitude helicopter missions, where aggressive terrain hugging maneuvers create minimal horizontal and vertical clearances and demand precise terrain positioning. Sole reliance on airborne precision navigation and stored terrain elevation data for above-ground-level (AGL) positioning severely limits the operational altitude of such systems. A Kalman filter is presented which blends radar altimeter returns, precision navigation, and stored terrain elevation data for AGL positioning. The filter is evaluated using low-altitude helicopter flight test data acquired over moderately rugged terrain. The proposed Kalman filter is found to remove large disparities in predicted AGL altitude (i.e., from airborne navigation and terrain elevation data) in the presence of measurement anomalies and dropouts. Previous work suggested a minimum clearance altitude of 220 ft AGL for a near-terrain guidance system; integration of a radar altimeter allows for operation of that system below 50 ft, subject to obstacle-avoidance limitations.

  1. Normobaric Hypoxia Exposure during Low Altitude Stay and Performance of Elite-Level Race-Walkers

    Directory of Open Access Journals (Sweden)

    Gaurav Sikri, AB Srinivasa

    2016-06-01

    Full Text Available We read with profound interest the article titled ‘Increased hypoxic dose after training at low altitude with 9h per night at 3000m normobaric hypoxia’ by Carr et al. (2015. Authors have concluded that low altitude (1380 m combined with normobaric hypoxia of 3000 m improves total haemoglobin mass (Hbmass and is an effective alternate method for training. Like other studies on elite athletes, the authors of present work have brought out that a major limitation was non-availability of a control group consisting of subjects undertaking same supervised training at normoxia. The total number of ‘possible’ subjects for control group which were taken from a previous study (Saunders et al., 2010 was 11 i.e placebo group (n = 6; 3 male and 3 female and Nocebo group (n = 5; 3 female and 2 male. It seems likely that authors of the present study have chosen only 10 subjects out of those 11. The criteria for exclusion of one subject and selection of 10 out of 11 subjects from the previous study to form the control group of the present study may require further elaboration.

  2. A New Perspective: Assessing the Spatial Distribution of Coral Bleaching with Unmanned Low Altitude Remote Sensing Systems

    Science.gov (United States)

    Levy, J.; Franklin, E. C.; Hunter, C. L.

    2016-12-01

    scientists a new perspective on meso-scale coral reef dynamics. We envision that similar low altitude aerial surveys will be incorporated as a standard component of shallow-water reef studies, especially on reefs too dangerous or remote for in situ surveys.

  3. Computational mission analysis and conceptual system design for super low altitude satellite

    Institute of Scientific and Technical Information of China (English)

    Ming Xu; Jinlong Wang; Nan Zhou

    2014-01-01

    This paper deals with system engineering and design methodology for super low altitude satel ites in the view of the com-putational mission analysis. Due to the slight advance of imaging instruments, such as the focus of camera and the image element of charge coupled device (CCD), it is an innovative and economical way to improve the camera’s resolution to enforce the satel ite to fly on the lower altitude orbit. DFH-3, the mature satel ite bus de-veloped by Chinese Academy of Space Technology, is employed to define the mass and power budgets for the computational mis-sion analysis and the detailed engineering design for super low altitude satel ites. An effective iterative algorithm is proposed to solve the ergodic representation of feasible mass and power bud-gets at the flight altitude under constraints. Besides, boundaries of mass or power exist for every altitude, where the upper boundary is derived from the maximum power, while the minimum thrust force holds the lower boundary before the power reaching the initial value. What’s more, an analytical algorithm is employed to numerical y investigate the coverage percentage over the altitude, so that the nominal altitude could be selected from al the feasi-ble altitudes based on both the mass and power budgets and the repetitive ground traces. The local time at the descending node is chosen for the nominal sun-synchronous orbit based on the average evaluation function. After determining the key orbital ele-ments based on the computational mission analysis, the detailed engineering design on the configuration and other subsystems, like power, telemetry telecontrol and communication (TT&C), and attitude determination and control system (ADCS), is performed based on the benchmark bus, besides, some improvements to the bus are also implemented to accommodate the flight at a super low altitude. Two operation strategies, drag-free closed-loop mode and on/off open-loop mode, are presented to maintain the satel

  4. Unmanned Aerial System (UAS) Traffic Management (UTM): Enabling Low-Altitude Airspace and UAS Operations

    Science.gov (United States)

    Kopardekar, Parimal H.

    2014-01-01

    Many civilian applications of Unmanned Aerial Systems (UAS) have been imagined ranging from remote to congested urban areas, including goods delivery, infrastructure surveillance, agricultural support, and medical services delivery. Further, these UAS will have different equipage and capabilities based on considerations such as affordability, and mission needs applications. Such heterogeneous UAS mix, along with operations such as general aviation, helicopters, gliders must be safely accommodated at lower altitudes. However, key infrastructure to enable and safely manage widespread use of low-altitude airspace and UAS operations therein does not exist. Therefore, NASA is exploring functional design, concept and technology development, and a prototype UAS Traffic Management (UTM) system. UTM will support safe and efficient UAS operations for the delivery of goods and services

  5. Statistical correlation of low-altitude ENA emissions with geomagnetic activity from IMAGE/MENA observations

    Science.gov (United States)

    Mackler, D. A.; Jahn, J.-M.; Perez, J. D.; Pollock, C. J.; Valek, P. W.

    2016-03-01

    Plasma sheet particles transported Earthward during times of active magnetospheric convection can interact with exospheric/thermospheric neutrals through charge exchange. The resulting Energetic Neutral Atoms (ENAs) are free to leave the influence of the magnetosphere and can be remotely detected. ENAs associated with low-altitude (300-800 km) ion precipitation in the high-latitude atmosphere/ionosphere are termed low-altitude emissions (LAEs). Remotely observed LAEs are highly nonisotropic in velocity space such that the pitch angle distribution at the time of charge exchange is near 90°. The Geomagnetic Emission Cone of LAEs can be mapped spatially, showing where proton energy is deposited during times of varying geomagnetic activity. In this study we present a statistical look at the correlation between LAE flux (intensity and location) and geomagnetic activity. The LAE data are from the MENA imager on the IMAGE satellite over the declining phase of solar cycle 23 (2000-2005). The SYM-H, AE, and Kp indices are used to describe geomagnetic activity. The goal of the study is to evaluate properties of LAEs in ENA images and determine if those images can be used to infer properties of ion precipitation. Results indicate a general positive correlation to LAE flux for all three indices, with the SYM-H showing the greatest sensitivity. The magnetic local time distribution of LAEs is centered about midnight and spreads with increasing activity. The invariant latitude for all indices has a slightly negative correlation. The combined results indicate LAE behavior similar to that of ion precipitation.

  6. Observations of a Unique Type of ULF Wave by Low-Altitude Space Technology 5 Satellites

    Science.gov (United States)

    Le, G.; Chi, P. J.; Strangeway, R. J.; Slavin, J. A.

    2011-01-01

    We report a unique type of ULF waves observed by low-altitude Space Technology 5 (ST-5) constellation mission. ST-5 is a three-microsatellite constellation deployed into a 300 x 4500 km dawn-dusk and Sun-synchronous polar orbit with 105.6deg inclination angle. Because of the Earth's rotation and the dipole tilt effect, the spacecraft's dawn-dusk orbit track can reach as low as subauroral latitudes during the course of a day. Whenever the spacecraft traverse the dayside closed field line region at subauroral latitudes, they frequently observe strong transverse oscillations at 30-200 mHz, or in the Pc2-3 frequency range. These Pc2-3 waves appear as wave packets with durations in the order of 5-10 min. As the maximum separations of the ST-5 spacecraft are in the order of 10 min, the three ST-5 satellites often observe very similar wave packets, implying these wave oscillations occur in a localized region. The coordinated ground-based magnetic observations at the spacecraft footprints, however, do not see waves in the Pc2-3 band; instead, the waves appear to be the common Pc4-5 waves associated with field line resonances. We suggest that these unique Pc2-3 waves seen by ST-5 are in fact the Doppler-shifted Pc4-5 waves as a result of rapid traverse of the spacecraft across the resonant field lines azimuthally at low altitudes. The observations with the unique spacecraft dawn-dusk orbits at proper altitudes and magnetic latitudes reveal the azimuthal characteristics of field line resonances.

  7. Use of low-altitude aerial photography to identify submersed aquatic macrophytes

    Science.gov (United States)

    Schloesser, Donald W.; Manny, Bruce A.; Brown, Charles L.; Jaworski, Eugene

    1987-01-01

    The feasibility of using low-altitude aerial photography to identify beds of submersed macrophytes is demonstrated. True color aerial photos and collateral ground survey information for submersed aquatic macrophyte beds at 10 sites in the St.Clair-Detroit River system were obtained in September 1978. Using the photos and collateral ground survey information, a dichotomous key was developed for the identification of six classes - beds of five genera of macrophytes and one substrate type. A test was prepared to determine how accurately photo interpreters could identify the six classes. The test required an interpreter to examine an unlabeled, outlined area on photographs and identify it using the key. Six interpreters were tested. One pair of interpreters was trained in the interpretation of a variety of aerial photos, a second pair had field experience in the collection and identification of submersed macrophytes in the river system, and a third pair had neither training in the interpretation of aerial photos nor field experience. The criteria that we developed were applied equally well by the interpretors, regardless of their training or experience. Overall accuracy (i.e., omission errors) of all six classes combined was 68% correct, whereas, overall accuracy of individual classes ranged from 50 to 100% correct. Mapping accuracy (i.e. omission and commission errors) of individual classes ranged from 36 to 75%. Although the key developed for this study has only limited application outside the context of the data and sites examined in this study, it is concluded that low-altitude aerial photography, together with limited amounts of collateral ground survey information, can be used to economically identify beds of submersed macrophytes in the St. Clair-Detroit River system and other similar water bodies.

  8. Mapping bathymetry based on waterlines observed from low altitude Helikite remote sensing platform

    Institute of Scientific and Technical Information of China (English)

    JO Young-Heon; SHA Jin; KWON Jae-Il; JUN Kicheon; PARK Jinku

    2015-01-01

    Mapping shoreline changes along coastal regions is critically important in monitoring continuously rising sea surface heights due to climate change and frequent severe storms. Thus, it is especially important if the region has very high tidal ranges over very gentle tidal flats, which is a very vulnerable region. Although the various remote sensing platforms can be used to map shoreline changes, the spatial and temporal resolutions are not enough to obtain it for a short time. Accordingly, in this study we introduce the newly developed low altitude Helikite remote sensing platform to achieve much better resolutions of shorelines and a bathymetry. The Helikite stands for Helium balloon and Kite, which is a kind of aerial platform that uses the advantages of both a Helium balloon and a kite. Field experiments were conducted in the Jaebu Island, off the coast of the west Korean Peninsula in January 29, 2011. In order to extract shorelines from the consecutive images taken by the low altitude Helikite remote sensing platform, active contours without edges (ACWE) is used. Edges or boundaries exist primarily on places between one type of objective and the other. Since the hydrodynamic pressure has an effect everywhere, the locations of the waterlines can be the isobath lines. We could map several waterlines, which would enable us to complete a local bathymetry map ranges from 35 to 60 cm depth. The error resulting from applying ACWE algorithm to the imagery to determine the waterline is approximately less than 1 m. Therefore, it is very unique way to obtain such high resolutions of bathymetry with high accuracy for the regions of extremely high tidal ranges for a short time.

  9. An Architectural Model for Component Groupware

    NARCIS (Netherlands)

    Farias, de Clever R.G.; Goncalves, Carlos E.; Rosatelli, Marta C.; Ferreira Pires, Luis; Sinderen, van Marten; Fuks, Hugo; Lukosch, Stephan; Salgado, Ana Carolina

    2005-01-01

    This paper proposes an architectural model to facilitate the design of component-based groupware systems. This architectural model has been defined based on (1) three pre-defined component types, (2) a refinement strategy that relies on these component types, (3) the identification of layers of coll

  10. Understanding symmetrical components for power system modeling

    CERN Document Server

    Das, J C

    2017-01-01

    This book utilizes symmetrical components for analyzing unbalanced three-phase electrical systems, by applying single-phase analysis tools. The author covers two approaches for studying symmetrical components; the physical approach, avoiding many mathematical matrix algebra equations, and a mathematical approach, using matrix theory. Divided into seven sections, topics include: symmetrical components using matrix methods, fundamental concepts of symmetrical components, symmetrical components –transmission lines and cables, sequence components of rotating equipment and static load, three-phase models of transformers and conductors, unsymmetrical fault calculations, and some limitations of symmetrical components.

  11. Detection of laurel wilt disease in avocado using low altitude aerial imaging.

    Science.gov (United States)

    de Castro, Ana I; Ehsani, Reza; Ploetz, Randy C; Crane, Jonathan H; Buchanon, Sherrie

    2015-01-01

    Laurel wilt is a lethal disease of plants in the Lauraceae plant family, including avocado (Persea americana). This devastating disease has spread rapidly along the southeastern seaboard of the United States and has begun to affect commercial avocado production in Florida. The main objective of this study was to evaluate the potential to discriminate laurel wilt-affected avocado trees using aerial images taken with a modified camera during helicopter surveys at low-altitude in the commercial avocado production area. The ability to distinguish laurel wilt-affected trees from other factors that produce similar external symptoms was also studied. RmodGB digital values of healthy trees and laurel wilt-affected trees, as well as fruit stress and vines covering trees were used to calculate several vegetation indices (VIs), band ratios, and VI combinations. These indices were subjected to analysis of variance (ANOVA) and an M-statistic was performed in order to quantify the separability of those classes. Significant differences in spectral values among laurel wilt affected and healthy trees were observed in all vegetation indices calculated, although the best results were achieved with Excess Red (ExR), (Red-Green) and Combination 1 (COMB1) in all locations. B/G showed a very good potential for separate the other factors with symptoms similar to laurel wilt-affected trees, such as fruit stress and vines covering trees, from laurel wilt-affected trees. These consistent results prove the usefulness of using a modified camera (RmodGB) to discriminate laurel wilt-affected avocado trees from healthy trees, as well as from other factors that cause the same symptoms and suggest performing the classification in further research. According to our results, ExR and B/G should be utilized to develop an algorithm or decision rules to classify aerial images, since they showed the highest capacity to discriminate laurel wilt-affected trees. This methodology may allow the rapid detection

  12. Detection of laurel wilt disease in avocado using low altitude aerial imaging.

    Directory of Open Access Journals (Sweden)

    Ana I de Castro

    Full Text Available Laurel wilt is a lethal disease of plants in the Lauraceae plant family, including avocado (Persea americana. This devastating disease has spread rapidly along the southeastern seaboard of the United States and has begun to affect commercial avocado production in Florida. The main objective of this study was to evaluate the potential to discriminate laurel wilt-affected avocado trees using aerial images taken with a modified camera during helicopter surveys at low-altitude in the commercial avocado production area. The ability to distinguish laurel wilt-affected trees from other factors that produce similar external symptoms was also studied. RmodGB digital values of healthy trees and laurel wilt-affected trees, as well as fruit stress and vines covering trees were used to calculate several vegetation indices (VIs, band ratios, and VI combinations. These indices were subjected to analysis of variance (ANOVA and an M-statistic was performed in order to quantify the separability of those classes. Significant differences in spectral values among laurel wilt affected and healthy trees were observed in all vegetation indices calculated, although the best results were achieved with Excess Red (ExR, (Red-Green and Combination 1 (COMB1 in all locations. B/G showed a very good potential for separate the other factors with symptoms similar to laurel wilt-affected trees, such as fruit stress and vines covering trees, from laurel wilt-affected trees. These consistent results prove the usefulness of using a modified camera (RmodGB to discriminate laurel wilt-affected avocado trees from healthy trees, as well as from other factors that cause the same symptoms and suggest performing the classification in further research. According to our results, ExR and B/G should be utilized to develop an algorithm or decision rules to classify aerial images, since they showed the highest capacity to discriminate laurel wilt-affected trees. This methodology may allow the

  13. Model checking of component connectors

    NARCIS (Netherlands)

    Izadi, Mohammad

    2011-01-01

    We present a framework for automata theoretic model checking of coordination systems specified in Reo coordination language. To this goal, we introduce Buchi automata of records (BAR) and their augmented version (ABAR) as an operational modeling formalism that covers several intended forms of behavi

  14. SOFTWARE RELIABILITY MODEL FOR COMPONENT INTERACTION MODE

    Institute of Scientific and Technical Information of China (English)

    Wang Qiang; Lu Yang; Xu Zijun; Han Jianghong

    2011-01-01

    With the rapid progress of component technology,the software development methodology of gathering a large number of components for designing complex software systems has matured.But,how to assess the application reliability accurately with the information of system architecture and the components reliabilities together has become a knotty problem.In this paper,the defects in formal description of software architecture and the limitations in existed model assumptions are both analyzed.Moreover,a new software reliability model called Component Interaction Mode (CIM) is proposed.With this model,the problem for existed component-based software reliability analysis models that cannot deal with the cases of component interaction with non-failure independent and non-random control transition is resolved.At last,the practice examples are presented to illustrate the effectiveness of this model

  15. Low altitude unmanned aerial vehicle for characterising remediation effectiveness following the FDNPP accident.

    Science.gov (United States)

    Martin, P G; Payton, O D; Fardoulis, J S; Richards, D A; Yamashiki, Y; Scott, T B

    2016-01-01

    On the 12th of March 2011, The Great Tōhoku Earthquake occurred 70 km off the eastern coast of Japan, generating a large 14 m high tsunami. The ensuing catalogue of events over the succeeding 12 d resulted in the release of considerable quantities of radioactive material into the environment. Important to the large-scale remediation of the affected areas is the accurate and high spatial resolution characterisation of contamination, including the verification of decontaminated areas. To enable this, a low altitude unmanned aerial vehicle equipped with a lightweight gamma-spectrometer and height normalisation system was used to produce sub-meter resolution maps of contamination. This system provided a valuable method to examine both contaminated and remediated areas rapidly, whilst greatly reducing the dose received by the operator, typically in localities formerly inaccessible to ground-based survey methods. The characterisation of three sites within Fukushima Prefecture is presented; one remediated (and a site of much previous attention), one un-remediated and a third having been subjected to an alternative method to reduce emitted radiation dose.

  16. Store-operated channels in the pulmonary circulation of high- and low-altitude neonatal lambs.

    Science.gov (United States)

    Parrau, Daniela; Ebensperger, Germán; Herrera, Emilio A; Moraga, Fernando; Riquelme, Raquel A; Ulloa, César E; Rojas, Rodrigo T; Silva, Pablo; Hernandez, Ismael; Ferrada, Javiera; Diaz, Marcela; Parer, Julian T; Cabello, Gertrudis; Llanos, Aníbal J; Reyes, Roberto V

    2013-04-15

    We determined whether store-operated channels (SOC) are involved in neonatal pulmonary artery function under conditions of acute and chronic hypoxia, using newborn sheep gestated and born either at high altitude (HA, 3,600 m) or low altitude (LA, 520 m). Cardiopulmonary variables were recorded in vivo, with and without SOC blockade by 2-aminoethyldiphenylborinate (2-APB), during basal or acute hypoxic conditions. 2-APB did not have effects on basal mean pulmonary arterial pressure (mPAP), cardiac output, systemic arterial blood pressure, or systemic vascular resistance in both groups of neonates. During acute hypoxia 2-APB reduced mPAP and pulmonary vascular resistance in LA and HA, but this reduction was greater in HA. In addition, isolated pulmonary arteries mounted in a wire myograph were assessed for vascular reactivity. HA arteries showed a greater relaxation and sensitivity to SOC blockers than LA arteries. The pulmonary expression of two SOC-forming subunits, TRPC4 and STIM1, was upregulated in HA. Taken together, our results show that SOC contribute to hypoxic pulmonary vasoconstriction in newborn sheep and that SOC are upregulated by chronic hypoxia. Therefore, SOC may contribute to the development of neonatal pulmonary hypertension. We propose SOC channels could be potential targets to treat neonatal pulmonary hypertension.

  17. UAV低空航测技术研究%UAV borne low altitude photogranmnetry system

    Institute of Scientific and Technical Information of China (English)

    林宗坚

    2011-01-01

    本文阐述无人飞行器(UAV)低空航测系统不同于普通航空摄影测量的技术特点,具体包括任务目标、飞行平台性能、成像传感器系统组成结构、数据处理的特殊技术等方面,尤其着重阐述了专门针对低空轻小型无人飞行器研制的具有自检校自稳定功能的组合宽角数码相机的设计原理.%Unmanned Aerial Vehicles (UAV) systems for low altitude aerial photogrammetry has different technical characteristics from the genera] aviation, including its mission objectives, flying platform performance, composition imaging sensor systems, data processing, particularly the principles of wide-angle digital camera with serf-calibration and serf-stabilizing design were described in detail in the paper.

  18. The Gravity Field of Mercury After the Messenger Low-Altitude Campaign

    Science.gov (United States)

    Mazarico, Erwan; Genova, Antonio; Goossens, Sander; Lemoine, Frank G.; Smith, David E.; Zuber, Maria T.; Neumann, Gary A.; Solomon, Sean C.

    2015-01-01

    The final year of the MESSENGER mission was designed to take advantage of the remaining propellant onboard to provide a series of lowaltitude observation campaigns and acquire novel scientific data about the innermost planet. The lower periapsis altitude greatly enhances the sensitivity to the short-wavelength gravity field, but only when the spacecraft is in view of Earth. After more than 3 years in orbit around Mercury, the MESSENGER spacecraft was tracked for the first time below 200-km altitude on 5 May 2014 by the NASA Deep Space Network (DSN). Between August and October, periapsis passages down to 25-km altitude were routinely tracked. These periods considerably improved the quality of the data coverage. Before the end of its mission, MESSENGER will fly at very low altitudes for extended periods of time. Given the orbital geometry, however the periapses will not be visible from Earth and so no new tracking data will be available for altitudes lower than 75 km. Nevertheless, the continuous tracking of MESSENGER in the northern hemisphere will help improve the uniformity of the spatial coverage at altitudes lower than 150 km, which will further improve the overall quality of the Mercury gravity field.

  19. Martian low-altitude magnetic topology deduced from MAVEN/SWEA observations

    Science.gov (United States)

    Xu, Shaosui; Mitchell, David; Liemohn, Michael; Fang, Xiaohua; Ma, Yingjuan; Luhmann, Janet; Brain, David; Steckiewicz, Morgane; Mazelle, Christian; Connerney, Jack; Jakosky, Bruce

    2017-02-01

    The Mars Atmosphere and Volatile Evolution mission has obtained comprehensive particle and magnetic field measurements. The Solar Wind Electron Analyzer provides electron energy-pitch angle distributions along the spacecraft trajectory that can be used to infer magnetic topology. This study presents pitch angle-resolved electron energy shape parameters that can distinguish photoelectrons from solar wind electrons, which we use to deduce the Martian magnetic topology and connectivity to the dayside ionosphere. Magnetic topology in the Mars environment is mapped in three dimensions for the first time. At low altitudes (connections through cross-terminator closed field lines than in the south. Although draped field lines with 100 km amplitude vertical fluctuations that intersect the electron exobase ( 160-220 km) in two locations could appear to be closed at the spacecraft, a more likely explanation is provided by crustal magnetic fields, which naturally have the required geometry. Around 30% of the time, we observe open field lines from 200 to 400 km, which implies three distinct topological layers over the northern hemisphere: closed field lines below 200 km, open field lines with foot points at lower latitudes that pass over the northern hemisphere from 200 to 400 km, and draped interplanetary magnetic field above 400 km. This study also identifies open field lines with one end attached to the dayside ionosphere and the other end connected with the solar wind, providing a path for ion outflow.

  20. Automatic Registration of Low Altitude UAV Sequent Images and Laser Point Clouds

    Directory of Open Access Journals (Sweden)

    CHEN Chi

    2015-05-01

    Full Text Available It is proposed that a novel registration method for automatic co-registration of unmanned aerial vehicle (UAV images sequence and laser point clouds. Firstly, contours of building roofs are extracted from the images sequence and laser point clouds using marked point process and local salient region detection, respectively. The contours from each data are matched via back-project proximity. Secondly, the exterior orientations of the images are recovered using a linear solver based on the contours corner pairs followed by a co-planar optimization which is implicated by the matched lines form contours pairs. Finally, the exterior orientation parameters of images are further optimized by matching 3D points generated from images sequence and laser point clouds using an iterative near the point (ICP algorithm with relative movement threshold constraint. Experiments are undertaken to check the validity and effectiveness of the proposed method. The results show that the proposed method achieves high-precision co-registration of low-altitude UAV image sequence and laser points cloud robustly. The accuracy of the co-produced DOMs meets 1:500 scale standards.

  1. Status of automatic guidance systems for rotorcraft in low altitude flight

    Science.gov (United States)

    Sridhar, Banavar; Cheng, Victor H. L.; Swenson, Harry N.

    1992-01-01

    Rotorcraft operating in high-threat environments fly close to the earth's surface to utilize surrounding terrain, vegetation, or man-made objects to minimize the risk of being detected by an enemy. The piloting of the rotorcraft is at best a very demanding task and the pilots need help from on-board automation tools in order to devote more time to mission-related activities. The Automated Nap-of-the-Earth (NOE) Flight Program is a cooperative NASA/Army program aimed at the development of technologies for enhancing piloted low-altitude/NOE flight path management and control through computer and sensor aiding. The long-term objective is to work towards achieving automation for aiding the pilot in NOE flight with a flight demonstration of resulting computer/sensor aiding concepts at an established course. The technology for pilot-centered NOE automation is not currently available. Success in automating NOE functions will depend on major breakthroughs in real-time flight path planning algorithms, effective methods for the pilot to interface to the automatic modes, understanding of visual images, sensor data processing/fusion, and sensor development. Our approach to developing the technologies required to solve this problem consist of the following phases: (1) algorithm development, (2) laboratory evaluation, (3) piloted ground simulation, and (4) evaluation in flight. An overview of the research in this area at NASA Ames Research Center is given.

  2. Variability in low altitude astronomical refraction as a function of altitude.

    Science.gov (United States)

    Sampson, Russell D; Lozowski, Edward P; Fathi-Nejad, Arsha

    2008-12-01

    Low altitude astronomical refraction (LAAR) of the setting Sun was measured over a sea horizon from a coastal location in Barbados, West Indies. The altitude of the upper limb of the Sun and the apparent horizon were determined using a digital video camera (Canon XL2) and a digital SLR camera (Canon EOS 5D). A total of 14 sunsets were measured between 2005 and 2007. From these measurements LAAR variability was estimated at 14 standard altitudes of the refracted Sun between 0 degrees .01 and 4 degrees .5. The relative variability decreases with increasing altitude from +/- 0.0195 of mean refraction at an altitude of 0 degrees .01 to +/- 0.0142 at 4 degrees .5. If extrapolated to an altitude of 15 degrees , a linear fit to the data produces a relative variability of +/- 0.0038 and an absolute variability of +/- 0(").45. Statistical analysis of the relative variability in LAAR appears to support the decreasing trend. However, error propagation analysis further suggests that the observed values of refraction may exceed the accuracy of the measurement system at altitudes higher than 2 degrees .

  3. Oil palm pest infestation monitoring and evaluation by helicopter-mounted, low altitude remote sensing platform

    Science.gov (United States)

    Samseemoung, Grianggai; Jayasuriya, Hemantha P. W.; Soni, Peeyush

    2011-01-01

    Timely detection of pest or disease infections is extremely important for controlling the spread of disease and preventing crop productivity losses. A specifically designed radio-controlled helicopter mounted low altitude remote sensing (LARS) platform can offer near-real-time results upon user demand. The acquired LARS images were processed to estimate vegetative-indices and thereby detecting upper stem rot (Phellinus Noxius) disease in both young and mature oil palm plants. The indices helped discriminate healthy and infested plants by visualization, analysis and presentation of digital imagery software, which were validated with ground truth data. Good correlations and clear data clusters were obtained in characteristic plots of normalized difference vegetation index (NDVI)LARS and green normalized difference vegetation indexLARS against NDVISpectro and chlorophyll content, by which infested plants were discriminated from healthy plants in both young and mature crops. The chlorophyll content values (μmol m-2) showed notable differences among clusters for healthy young (972 to 1100), for infested young (253 to 400), for healthy mature (1210 to 1500), and for infested mature (440 to 550) oil palm. The correlation coefficients (R2) were in a reasonably acceptable range (0.62 to 0.88). The vegetation indices based on LARS images, provided satisfactory results when compared to other approaches. The developed technology showed promising scope for medium and large plantations.

  4. Inferring electromagnetic ion cyclotron wave intensity from low altitude POES proton flux measurements: A detailed case study with conjugate Van Allen Probes observations

    Science.gov (United States)

    Zhang, Yang; Shi, Run; Ni, Binbin; Gu, Xudong; Zhang, Xianguo; Zuo, Pingbing; Fu, Song; Xiang, Zheng; Wang, Qi; Cao, Xing; Zou, Zhengyang

    2017-03-01

    Electromagnetic ion cyclotron (EMIC) waves play an important role in the magnetospheric particle dynamics and can lead to resonant pitch-angle scattering and ultimate precipitation of ring current protons. Commonly, the statistics of in situ EMIC wave measurements is adopted for quantitative investigation of wave-particle interaction processes, which however becomes questionable for detailed case studies especially during geomagnetic storms and substorms. Here we establish a novel technique to infer EMIC wave amplitudes from low-altitude proton measurements onboard the Polar Operational Environmental Satellites (POES). The detailed procedure is elaborated regarding how to infer the EMIC wave intensity for one specific time point. We then test the technique with a case study comparing the inferred root-mean-square (RMS) EMIC wave amplitude with the conjugate Van Allen Probes EMFISIS wave measurements. Our results suggest that the developed technique can reasonably estimate EMIC wave intensities from low-altitude POES proton flux data, thereby providing a useful tool to construct a data-based, near-real-time, dynamic model of the global distribution of EMIC waves once the proton flux measurements from multiple POES satellites are available for any specific time period.

  5. The prevalence and severity of dental fluorosis in the high and low altitude parts of Central Plateau, Nigeria.

    Science.gov (United States)

    Akosu, T J; Zoakah, A I; Chirdan, O A

    2009-09-01

    To compare the prevalence and severity of dental fluorosis in the high and low altitude parts of the Central Senatorial District of Plateau State. The study was cross-sectional and descriptive. The community based study was carried out in Central Plateau Nigeria, in 2005. The study subjects were 12-15 year old life long residents selected using the multistage sampling technique. One Local Government Area each was randomly selected from the high and low altitude parts of the district and from each selected Local Government Area two health districts were randomly selected with probability proportional to size. From each of the selected health Districts two major settlements were selected again with probability proportional to size. 12-15 year old life long residents of the selected settlements were studied. Each respondent completed an interviewer administered questionnaire after which he/she was clinically examined to ascertain his/her fluorosis status. Samples of water were collected from water sources consumed by the respondents in each settlement. The main outcome measures were presence and severity of dental fluorosis as measured by the Thylstrup and Fejerskov index. (TF score). One thousand one hundred children were studied, 554 (50.4%) from the high altitude part of the district and 546 (49.6%) from the low altitude part. Fluorosis prevalence was 12.9% in the district, but significantly higher (22.2%) in the high altitude areas compared to the low altitude ones (3.5%). The severest form of fluorosis in the district was TF 6 for tooth 14 and TF 5 for tooth 11. The prevalence and severity of dental fluorosis is significantly higher in the high altitude parts of the District compared to the low altitude ones. Efforts are needed to further investigate and control the problem.

  6. Detection of Solid Tides on Europa Through Ground-Tracking of a Low-Altitude, Altimeter- Equipped Orbiter

    Science.gov (United States)

    Casotto, S.; Padovan, S.; Bardella, M.

    2007-12-01

    The possibility of detecting a global liquid ocean beneath the icy crust of Europa without the use of landers or ice penetrators rests on the measurement of the Love numbers h2 and k2. These are respectively related to the radial deformation of the surface and the consequent tidally-induced variation of the gravitational field of this icy satellite. Depending on the rigidity of the icy crust, the response of the Europan surface to the tidal forces gives an indication of the depth of a possible subsurface ocean. Previous studies in this area have addressed the detection of tidal surface deformations through the analysis of the tidally induced orbital perturbations of a Europan orbiter. As a preliminary study in preparation for future missions to Europa, as in the LAPLACE proposal to the European Space Agency, the approach followed here is to introduce the presence of an onboard altimeter. In this study we then generate synthetic measurements taken from an altimeter-equipped, low-altitude orbiter, supplemented with Earth-based tracking of the orbiter. For simplicity, ground-tracking is simulated as a range data-type. Altimeter measurements are simulated using parameters based on available models for the interior of Europa derived from Galileo mission data. Reference orbits were obtained by numerical investigations of the dynamically unstable near-Europa environment. Orbits were found to be stable over periods of approximately one to three months at altitudes of 100 km and inclinations varying from 75 degrees to 105 degrees. The measurements are consequently simulated over a period of one to two months. Under the hypothesis that Europan gravity field information of sufficient accuracy has been obtained in the first phase of the mission, the simulations address the detection of the solid tide related Love parameters h2 and k2. Results of this sensitivity study will be presented for a variety of orbital configurations with the aim to help in the design of future Europa

  7. Two-component Abelian sandpile models.

    Science.gov (United States)

    Alcaraz, F C; Pyatov, P; Rittenberg, V

    2009-04-01

    In one-component Abelian sandpile models, the toppling probabilities are independent quantities. This is not the case in multicomponent models. The condition of associativity of the underlying Abelian algebras imposes nonlinear relations among the toppling probabilities. These relations are derived for the case of two-component quadratic Abelian algebras. We show that Abelian sandpile models with two conservation laws have only trivial avalanches.

  8. Propagation of whistler-mode chorus to low altitudes: divergent ray trajectories and ground accessibility

    Directory of Open Access Journals (Sweden)

    J. Chum

    2005-12-01

    Full Text Available We investigate the ray trajectories of nonductedly propagating lower-band chorus waves with respect to their initial angle θ0, between the wave vector and ambient magnetic field. Although we consider a wide range of initial angles θ0, in order to be consistent with recent satellite observations, we pay special attention to the intervals of initial angles θ0, for which the waves propagate along the field lines in the source region, i.e. we mainly focus on waves generated with &theta0 within an interval close to 0° and on waves generated within an interval close to the Gendrin angle. We demonstrate that the ray trajectories of waves generated within an interval close to the Gendrin angle with a wave vector directed towards the lower L-shells (to the Earth significantly diverge at the frequencies typical for the lower-band chorus. Some of these diverging trajectories reach the topside ionosphere having θ close to 0°; thus, a part of the energy may leak to the ground at higher altitudes where the field lines have a nearly vertical direction. The waves generated with different initial angles are reflected. A small variation of the initial wave normal angle thus very dramatically changes the behaviour of the resulting ray. Although our approach is rather theoretical, based on the ray tracing simulation, we show that the initial angle θ0 of the waves reaching the ionosphere (possibly ground is surprisingly close - differs just by several degrees from the initial angles which fits the observation of magnetospherically reflected chorus revealed by CLUSTER satellites. We also mention observations of diverging trajectories on low altitude satellites.

  9. Determining Spectral Reflectance Coefficients from Hyperspectral Images Obtained from Low Altitudes

    Science.gov (United States)

    Walczykowski, P.; Jenerowicz, A.; Orych, A.; Siok, K.

    2016-06-01

    Remote Sensing plays very important role in many different study fields, like hydrology, crop management, environmental and ecosystem studies. For all mentioned areas of interest different remote sensing and image processing techniques, such as: image classification (object and pixel- based), object identification, change detection, etc. can be applied. Most of this techniques use spectral reflectance coefficients as the basis for the identification and distinction of different objects and materials, e.g. monitoring of vegetation stress, identification of water pollutants, yield identification, etc. Spectral characteristics are usually acquired using discrete methods such as spectrometric measurements in both laboratory and field conditions. Such measurements however can be very time consuming, which has led many international researchers to investigate the reliability and accuracy of using image-based methods. According to published and ongoing studies, in order to acquire these spectral characteristics from images, it is necessary to have hyperspectral data. The presented article describes a series of experiments conducted using the push-broom Headwall MicroHyperspec A-series VNIR. This hyperspectral scanner allows for registration of images with more than 300 spectral channels with a 1.9 nm spectral bandwidth in the 380- 1000 nm range. The aim of these experiments was to establish a methodology for acquiring spectral reflectance characteristics of different forms of land cover using such sensor. All research work was conducted in controlled conditions from low altitudes. Hyperspectral images obtained with this specific type of sensor requires a unique approach in terms of post-processing, especially radiometric correction. Large amounts of acquired imagery data allowed the authors to establish a new post- processing approach. The developed methodology allowed the authors to obtain spectral reflectance coefficients from a hyperspectral sensor mounted on an

  10. DETERMINING SPECTRAL REFLECTANCE COEFFICIENTS FROM HYPERSPECTRAL IMAGES OBTAINED FROM LOW ALTITUDES

    Directory of Open Access Journals (Sweden)

    P. Walczykowski

    2016-06-01

    Full Text Available Remote Sensing plays very important role in many different study fields, like hydrology, crop management, environmental and ecosystem studies. For all mentioned areas of interest different remote sensing and image processing techniques, such as: image classification (object and pixel- based, object identification, change detection, etc. can be applied. Most of this techniques use spectral reflectance coefficients as the basis for the identification and distinction of different objects and materials, e.g. monitoring of vegetation stress, identification of water pollutants, yield identification, etc. Spectral characteristics are usually acquired using discrete methods such as spectrometric measurements in both laboratory and field conditions. Such measurements however can be very time consuming, which has led many international researchers to investigate the reliability and accuracy of using image-based methods. According to published and ongoing studies, in order to acquire these spectral characteristics from images, it is necessary to have hyperspectral data. The presented article describes a series of experiments conducted using the push-broom Headwall MicroHyperspec A-series VNIR. This hyperspectral scanner allows for registration of images with more than 300 spectral channels with a 1.9 nm spectral bandwidth in the 380- 1000 nm range. The aim of these experiments was to establish a methodology for acquiring spectral reflectance characteristics of different forms of land cover using such sensor. All research work was conducted in controlled conditions from low altitudes. Hyperspectral images obtained with this specific type of sensor requires a unique approach in terms of post-processing, especially radiometric correction. Large amounts of acquired imagery data allowed the authors to establish a new post- processing approach. The developed methodology allowed the authors to obtain spectral reflectance coefficients from a hyperspectral sensor

  11. Flight evaluation of a computer aided low-altitude helicopter flight guidance system

    Science.gov (United States)

    Swenson, Harry N.; Jones, Raymond D.; Clark, Raymond

    1993-01-01

    The Flight Systems Development branch of the U.S. Army's Avionics Research and Development Activity (AVRADA) and NASA Ames Research Center have developed for flight testing a Computer Aided Low-Altitude Helicopter Flight (CALAHF) guidance system. The system includes a trajectory-generation algorithm which uses dynamic programming and a helmet-mounted display (HMD) presentation of a pathway-in-the-sky, a phantom aircraft, and flight-path vector/predictor guidance symbology. The trajectory-generation algorithm uses knowledge of the global mission requirements, a digital terrain map, aircraft performance capabilities, and precision navigation information to determine a trajectory between mission way points that seeks valleys to minimize threat exposure. This system was developed and evaluated through extensive use of piloted simulation and has demonstrated a 'pilot centered' concept of automated and integrated navigation and terrain mission planning flight guidance. This system has shown a significant improvement in pilot situational awareness, and mission effectiveness as well as a decrease in training and proficiency time required for a near terrain, nighttime, adverse weather system. AVRADA's NUH-60A STAR (Systems Testbed for Avionics Research) helicopter was specially modified, in house, for the flight evaluation of the CALAHF system. The near terrain trajectory generation algorithm runs on a multiprocessor flight computer. Global Positioning System (GPS) data are integrated with Inertial Navigation Unit (INU) data in the flight computer to provide a precise navigation solution. The near-terrain trajectory and the aircraft state information are passed to a Silicon Graphics computer to provide the graphical 'pilot centered' guidance, presented on a Honeywell Integrated Helmet And Display Sighting System (IHADSS). The system design, piloted simulation, and initial flight test results are presented.

  12. Remote sensing analysis of a Mediterranean thundersnow and low-altitude heavy snowfall event

    Science.gov (United States)

    Bech, Joan; Pineda, Nicolau; Rigo, Tomeu; Aran, Montserrat

    2013-04-01

    On the 8 of March 2010 a heavy snowfall accompanied by lightning occurred over Catalonia (NE Spain), in the Western Mediterranean. Total lightning observations included 101 cloud-to-ground flashes and 169 intra-cloud flashes. Precipitation amounts in 24 h exceeded 100 mm and snow depths over low altitude terrain, where snow is rare, surpassed 30 cm. Snow accumulations collapsed the regional communication transport network and the border with France was closed several hours. Occurrence of wet snow combined with increasingly strong winds caused widespread damage over large forest areas estimated in more than 20 MEur and affected dramatically the high voltage power line distribution grid due to ice accretion, particularly in NE Catalonia where 33 high power electrical towers were knocked down. The meteorological framework at synoptic scale was dominated at low levels by a northern flow over Iberia due to a blocking high pressure system on the British Isles, and an upper level cold trough, which favoured a rapid cyclogenesis over the Mediterranean (9.2 hPa drop in 12 h). Weather radar observations indicated predominance of stratiform precipitation and some low-topped convection, with maximum reflectivities and tops mostly below 40 dBZ and 4 km respectively. The presence of mesoscale gravity waves, caused by wind-shear instability, is suggested as a triggering element for convection and subsequent lightning. Comparison of accumulated precipitation and lightning maps indicated clusters of lightning data unrelated to precipitation maxima. Further investigation of total lightning characteristics and co-located radar observations suggested a triggering effect by tall telecommunication towers inducing cloud-to-ground flashes and subsequent intra-cloud lightning.

  13. Generation of remotely sensed reference data using low altitude, high spatial resolution hyperspectral imagery

    Science.gov (United States)

    Williams, McKay D.; van Aardt, Jan; Kerekes, John P.

    2016-05-01

    Exploitation of imaging spectroscopy (hyperspectral) data using classification and spectral unmixing algorithms is a major research area in remote sensing, with reference data required to assess algorithm performance. However, we are limited by our inability to generate rapid, accurate, and consistent reference data, thus making quantitative algorithm analysis difficult. As a result, many investigators present either limited quantitative results, use synthetic imagery, or provide qualitative results using real imagery. Existing reference data typically classify large swaths of imagery pixel-by-pixel, per cover type. While this type of mapping provides a first order understanding of scene composition, it is not detailed enough to include complexities such as mixed pixels, intra-end-member variability, and scene anomalies. The creation of more detailed ground reference data based on field work, on the other hand, is complicated by the spatial scale of common hyperspectral data sets. This research presents a solution to this challenge via classification of low altitude, high spatial resolution (1m GSD) National Ecological Observatory Network (NEON) hyperspectral imagery, on a pixel-by-pixel basis, to produce sub-pixel reference data for high altitude, lower spatial resolution (15m GSD) AVIRIS imagery. This classification is performed using traditional classification techniques, augmented by (0.3m GSD) NEON RGB data. This paper provides a methodology for generating large scale, sub-pixel reference data for AVIRIS imagery using NEON imagery. It also addresses challenges related to the fusion of multiple remote sensing modalities (e.g., different sensors, sensor look angles, spatial registration, varying scene illumination, etc.). A new algorithm for spatial registration of hyperspectral imagery with disparate resolutions is presented. Several versions of reference data results are compared to each other and to direct spectral unmixing of AVIRIS data. Initial results are

  14. A Linguistic Model in Component Oriented Programming

    Science.gov (United States)

    Crăciunean, Daniel Cristian; Crăciunean, Vasile

    2016-12-01

    It is a fact that the component-oriented programming, well organized, can bring a large increase in efficiency in the development of large software systems. This paper proposes a model for building software systems by assembling components that can operate independently of each other. The model is based on a computing environment that runs parallel and distributed applications. This paper introduces concepts as: abstract aggregation scheme and aggregation application. Basically, an aggregation application is an application that is obtained by combining corresponding components. In our model an aggregation application is a word in a language.

  15. DOA Estimation of Low Altitude Target Based on Adaptive Step Glowworm Swarm Optimization-multiple Signal Classification Algorithm

    Directory of Open Access Journals (Sweden)

    Zhou Hao

    2015-06-01

    Full Text Available The traditional MUltiple SIgnal Classification (MUSIC algorithm requires significant computational effort and can not be employed for the Direction Of Arrival (DOA estimation of targets in a low-altitude multipath environment. As such, a novel MUSIC approach is proposed on the basis of the algorithm of Adaptive Step Glowworm Swarm Optimization (ASGSO. The virtual spatial smoothing of the matrix formed by each snapshot is used to realize the decorrelation of the multipath signal and the establishment of a fullorder correlation matrix. ASGSO optimizes the function and estimates the elevation of the target. The simulation results suggest that the proposed method can overcome the low altitude multipath effect and estimate the DOA of target readily and precisely without radar effective aperture loss.

  16. Unmanned Aircraft System (UAS) Traffic Management (UTM): Enabling Civilian Low-Altitude Airspace and Unmanned Aerial System Operations

    Science.gov (United States)

    Kopardekar, Parimal Hemchandra

    2016-01-01

    Just a year ago we laid out the UTM challenges and NASA's proposed solutions. During the past year NASA's goal continues to be to conduct research, development and testing to identify airspace operations requirements to enable large-scale visual and beyond visual line-of-sight UAS operations in the low-altitude airspace. Significant progress has been made, and NASA is continuing to move forward.

  17. Impacts of more frequent droughts on a relict low-altitude Pinus uncinata stand in the French Alps

    Directory of Open Access Journals (Sweden)

    Christophe eCorona

    2015-01-01

    Full Text Available Cold microclimatic conditions provide exceptional microhabitats to Pinus uncinata stands occurring at abnormally low altitudes in seven paleorefugia of the northern French Alps. Here, P. uncinata is located at the lower bounds of its ecological limits and therefore expected to provide a sensitive indicator of climate change processes. We used dendrochronological analysis to study the growth patterns of closely spaced chronologies across an elevational transect and compare a relict low-altitude to a P. uncinata stand located at the alpine treeline. Two detrending procedures are used to reveal high and low-frequency wavelengths embedded in annually resolved ring-width series. Growth response of P. uncinata to instrumental temperature and precipitation data is investigated by means of moving response function analyses. Results show an increase in the sensitivity of tree-ring widths to drought during previous summer in both stands. At the treeline stand, an increasing correlation with fall temperature is observed whereby low-frequency variability of fall temperature and radial tree growth increased in two synchronous steps around ~1930 and from ~1980–present. At the low-altitude stand, P. uncinata appears more drought sensitive and exhibits a sharp growth decline since the mid-1980s, coinciding with increasing summer temperatures. Growth divergence between the two stands can be observed since the mid-1980s. We argue that the positive growth trend at the high-altitude stand is due to increasing fall temperatures which would favor the formation of metabolic reserves in conjunction with atmospheric CO2 enrichment that in turn would facilitate improved water use efficiency. At the relict low-altitude stand, in contrast, it seems that improved water use efficiency cannot compensate for the increase in summer temperatures.

  18. Two-Dimensional FCT Model of Low-Altitude Nuclear Effects.

    Science.gov (United States)

    1980-10-16

    8120 Woodmont Avenue U.S. Army Missile Command Bethesda, MD 20014 Redstone Arsenal, AL 35809 Olcy Attn MOCA -ADL (lech Lib) Olcy Attn DRDMI-XS Olcy...Systems Group University of Now Mexico 201 Lowell Street University Station Wilmington, mA 01887 P 0 Box 25 Olcy Attn Library A830 Albuquerque, NH 87131

  19. Multi-sensor field trials for detection and tracking of multiple small unmanned aerial vehicles flying at low altitude

    Science.gov (United States)

    Laurenzis, Martin; Hengy, Sebastien; Hommes, Alexander; Kloeppel, Frank; Shoykhetbrod, Alex; Geibig, Thomas; Johannes, Winfried; Naz, Pierre; Christnacher, Frank

    2017-05-01

    Small unmanned aerial vehicles (UAV) flying at low altitude are becoming more and more a serious threat in civilian and military scenarios. In recent past, numerous incidents have been reported where small UAV were flying in security areas leading to serious danger to public safety or privacy. The detection and tracking of small UAV is a widely discussed topic. Especially, small UAV flying at low altitude in urban environment or near background structures and the detection of multiple UAV at the same time is challenging. Field trials were carried out to investigate the detection and tracking of multiple UAV flying at low altitude with state of the art detection technologies. Here, we present results which were achieved using a heterogeneous sensor network consisting of acoustic antennas, small frequency modulated continuous wave (FMCW) RADAR systems and optical sensors. While acoustics, RADAR and LiDAR were applied to monitor a wide azimuthal area (360°) and to simultaneously track multiple UAV, optical sensors were used for sequential identification with a very narrow field of view.

  20. Radial distribution of the inner magnetosphere plasma pressure using low-altitude satellite data during geomagnetic storm: the March 1-8, 1982 Event

    CERN Document Server

    Stepanova, M; Bosqued, J M

    2007-01-01

    Plasma pressure distribution in the inner magnetosphere is one of the key parameters for understanding the main magnetospheric processes including geomagnetic storms and substorms. However, the pressure profiles obtained from in-situ particle measurements by the high-altitude satellites do not allow tracking the pressure variations related to the storms and substorms, because a time interval needed to do this generally exceeds the characteristic times of them. On contrary, fast movement of low-altitude satellites makes it possible to retrieve quasi-instantaneous profiles of plasma pressure along the satellite trajectory, using the fluxes of precipitating particles. For this study, we used the Aureol-3 satellite data for plasma pressure estimation, and the IGRF, Tsyganenko 2001 and Tsyganenko 2004 storm time geomagnetic field models for the pressure mapping into the equatorial plane. It was found that during quiet geomagnetic condition the radial pressure profiles obtained coincide with the profiles, obtained ...

  1. Damage modelling in plasma facing components

    Energy Technology Data Exchange (ETDEWEB)

    Martin, E. [Universite Bordeaux 1, UMR 5801 (CNRS-SPS-CEA-UB1), Laboratoire des Composites Thermostructuraux, F-33600 Pessac (France)], E-mail: martin@lcts.u-bordeaux1.fr; Camus, G. [Universite Bordeaux 1, UMR 5801 (CNRS-SPS-CEA-UB1), Laboratoire des Composites Thermostructuraux, F-33600 Pessac (France); Schlosser, J.; Chevet, G. [Association Euratom-CEA, DSM/DRFC, CEA Cadarache, St. Paul Lez Durance (France)

    2009-04-30

    The plasma facing components of controlled fusion devices are submitted to high heat fluxes in operating conditions (from 10 to 20 MW/m{sup 2}). These components are made of a carbon/carbon composite tile bonded to a copper alloy heat sink. Due to the thermal expansion mismatch between the composite and the copper alloy, significant stresses may develop during fabrication and under heat load inducing damage in the composite material as well as at the copper/composite interface. The present study describes a modelling approach aimed at predicting damage development in plasma facing components. For this purpose, damage laws related to the non-linear behaviour of both the composite material and the copper/composite joint have been identified. These constitutive laws were then introduced in a numerical model representative of a plasma facing component. Results show the development of damage within the assembly submitted to a heat load.

  2. Depth Estimation of Submerged Aquatic Vegetation in Clear Water Streams Using Low-Altitude Optical Remote Sensing

    Directory of Open Access Journals (Sweden)

    Fleur Visser

    2015-09-01

    Full Text Available UAVs and other low-altitude remote sensing platforms are proving very useful tools for remote sensing of river systems. Currently consumer grade cameras are still the most commonly used sensors for this purpose. In particular, progress is being made to obtain river bathymetry from the optical image data collected with such cameras, using the strong attenuation of light in water. No studies have yet applied this method to map submergence depth of aquatic vegetation, which has rather different reflectance characteristics from river bed substrate. This study therefore looked at the possibilities to use the optical image data to map submerged aquatic vegetation (SAV depth in shallow clear water streams. We first applied the Optimal Band Ratio Analysis method (OBRA of Legleiter et al. (2009 to a dataset of spectral signatures from three macrophyte species in a clear water stream. The results showed that for each species the ratio of certain wavelengths were strongly associated with depth. A combined assessment of all species resulted in equally strong associations, indicating that the effect of spectral variation in vegetation is subsidiary to spectral variation due to depth changes. Strongest associations (R2-values ranging from 0.67 to 0.90 for different species were found for combinations including one band in the near infrared (NIR region between 825 and 925 nm and one band in the visible light region. Currently data of both high spatial and spectral resolution is not commonly available to apply the OBRA results directly to image data for SAV depth mapping. Instead a novel, low-cost data acquisition method was used to obtain six-band high spatial resolution image composites using a NIR sensitive DSLR camera. A field dataset of SAV submergence depths was used to develop regression models for the mapping of submergence depth from image pixel values. Band (combinations providing the best performing models (R2-values up to 0.77 corresponded with the

  3. Depth Estimation of Submerged Aquatic Vegetation in Clear Water Streams Using Low-Altitude Optical Remote Sensing.

    Science.gov (United States)

    Visser, Fleur; Buis, Kerst; Verschoren, Veerle; Meire, Patrick

    2015-09-30

    UAVs and other low-altitude remote sensing platforms are proving very useful tools for remote sensing of river systems. Currently consumer grade cameras are still the most commonly used sensors for this purpose. In particular, progress is being made to obtain river bathymetry from the optical image data collected with such cameras, using the strong attenuation of light in water. No studies have yet applied this method to map submergence depth of aquatic vegetation, which has rather different reflectance characteristics from river bed substrate. This study therefore looked at the possibilities to use the optical image data to map submerged aquatic vegetation (SAV) depth in shallow clear water streams. We first applied the Optimal Band Ratio Analysis method (OBRA) of Legleiter et al. (2009) to a dataset of spectral signatures from three macrophyte species in a clear water stream. The results showed that for each species the ratio of certain wavelengths were strongly associated with depth. A combined assessment of all species resulted in equally strong associations, indicating that the effect of spectral variation in vegetation is subsidiary to spectral variation due to depth changes. Strongest associations (R²-values ranging from 0.67 to 0.90 for different species) were found for combinations including one band in the near infrared (NIR) region between 825 and 925 nm and one band in the visible light region. Currently data of both high spatial and spectral resolution is not commonly available to apply the OBRA results directly to image data for SAV depth mapping. Instead a novel, low-cost data acquisition method was used to obtain six-band high spatial resolution image composites using a NIR sensitive DSLR camera. A field dataset of SAV submergence depths was used to develop regression models for the mapping of submergence depth from image pixel values. Band (combinations) providing the best performing models (R²-values up to 0.77) corresponded with the OBRA

  4. Two-component model of solar plages

    Institute of Scientific and Technical Information of China (English)

    LI; Jianping(李建平); DING; Mingde(丁明德); FANG; Cheng(方成)

    2002-01-01

    By use of the 2-m Mcmath-Pierce telescope at Kitt Peak, the high-quality spectra of a plage with moderate brightness near the center of solar disk were obtained. The data include seven spectral lines, which are Hα, Hβ, CaII H and K lines and the infrared triplet. With the consideration of fine structures of solar plages, a two-component atmospheric model is constructed by keeping the cool component to be the quiet atmosphere. Three cases of the hot component are given for different filling factors where the temperature and density distribution are adjusted in order to reproduce the seven observed spectral profiles. We also briefly discuss the influence of the column density at the base of the corona, m0, and the macro-turbulent velocity on the required filling factor and computed profiles. The two-component model is compared with precious one-component semi-empirical models. The limitation of the model is pointed out and further improvement is indicated.

  5. Overview of the model component in ECOCLIM

    DEFF Research Database (Denmark)

    Geels, Camilla; Boegh, Eva; Bendtsen, J

    As part of the Danish strategic research project ECOCLIM: Ecosystems Surface Exchange of Greenhouse Gases in an Environment of Changing Anthropogenic and Climate forcing a model system will be developed. This model system will be based on both terrestrial and marine ecosystems in order to be able...... and atmospheric models. We will use the model system to 1) quantify the potential effects of climate change on ecosystem exchange of GHG and 2) estimate the impacts of changes in management practices including land use change and nitrogen (N) loads. Here the various model components will be introduced...

  6. Mobility Management of VHF Dynamic Access in Low-altitude Airspace%低空空域VHF动态接入移动性管理

    Institute of Scientific and Technical Information of China (English)

    严雯

    2014-01-01

    The mobility management of Very High Frequency(VHF) dynamic access in low-altitude air-space is the key to realize uninterrupted and cross regional communication for low attitude flight. According to the low-altitude airspace communication network architecture,a hierarchical mobility management model is designed by Home Location Register/Visitor Location Register ( HLR/VLR ) mechanism with the suc-cessful experiences of Global System for Mobile( GSM) ,which dresses the issue of aircrafts location man-agement effectively. Registration,logging in/out,inter and intra station mobility management are described in detail. Finally,the delay of mobility management is analyzed and simulation is demonstrated,which lays foundation for further research on mobility management of VHF dynamic access.%低空空域超短波( VHF)动态接入移动性管理技术是保障低空飞行不间断、跨区域通信的关键。根据低空空管通信网络框架,设计了低空空管二级移动性管理模型;借鉴GSM经典移动性管理模型,引入访问/归属位置寄存器机制,解决了地面通信网有效管理低空飞行器位置信息的问题。详细阐述了登记注册、入网/退网、站内移动性管理和站间移动性管理等流程。最后,分析了移动性管理时延,并给出了系统演示和仿真,为进一步研究打下了基础。

  7. Learning Software Component Model for Online Tutoring

    Directory of Open Access Journals (Sweden)

    K. Duraiswamy

    2012-01-01

    Full Text Available Problem statement: Web services are interface elements which allow applications to render functional services to requesting clients using open standard protocols. A lecture method combines both social association and urban processing as course design and delivery is termed as Interface Learning. Many Interface learning services is presenting through online. To make an online tutoring scheme more effective, the previous study used web services and application programs like instant messaging based on environments in which students reside. But the downside is that it is difficult to maintain the service request queues online. The services and data storage processes are inefficient. Approach: To overcome all the above issues, a Learning Software Component Model (LSCM framework is formed in the present study to build a component model based on communication services available on the network. In addition to this, the proposed software component modeled with Learning Object (LO aspects integrates the related sub hierarchical components with the main component object framework. Based on LSCM, training schedules are identified efficiently. Results: The proposed LSCM framework is experimented to show the performance improvement with the previous online tutoring scheme based on web services in terms of delivery report, maintenance of tutoring sessions and reliability. Conclusion: Compared to an existing online tutoring through web services, the proposed LSCM framework performance is 75% better in providing learning services to the providers.

  8. Modeling structural dynamic behavior of SSME components

    Science.gov (United States)

    Kiefling, Larry A.; Saxon, J. B.; Prickett, T. L.

    1991-01-01

    FEM studies are presented of the nozzle and the low-pressure fuel-pump inducer designs for the Space Shuttle Main Engine (SSME) to analyze the effects of structural vibrations. FEM preprocessing software based on a CAD system is employed to develop a model of the component's sophisticated geometry. The nozzle geometry is also defined by means of the preprocessing technique and subsequently analyzed with respect to time-transient loading. The analysis is conducted with a Cray supercomputer using the SPAR/EAL FEM program. The investigation of the nozzle demonstrates the advantageous use of symmetry in the determination of nozzle response to SSME start-up transients. Plots of time vs strain are developed for gages on the nozzle wall and steerhorn tubing. The results of the inducer modeling are found to be adequate for investigating the component's principle modes, and the nozzle results indicate the suitability of the FEM techniques for optimizing the design of engine components.

  9. Independent Component Analysis in Multimedia Modeling

    DEFF Research Database (Denmark)

    Larsen, Jan; Hansen, Lars Kai; Kolenda, Thomas

    2003-01-01

    Modeling of multimedia and multimodal data becomes increasingly important with the digitalization of the world. The objective of this paper is to demonstrate the potential of independent component analysis and blind sources separation methods for modeling and understanding of multimedia data, which...... largely refers to text, images/video, audio and combinations of such data. We review a number of applications within single and combined media with the hope that this might provide inspiration for further research in this area. Finally, we provide a detailed presentation of our own recent work on modeling...... combined text/image data for the purpose of cross-media retrieval....

  10. Independent Component Analysis in Multimedia Modeling

    DEFF Research Database (Denmark)

    Larsen, Jan

    Modeling of multimedia and multimodal data becomes increasingly important with the digitalization of the world. The objective of this paper is to demonstrate the potential of independent component analysis and blind sources separation methods for modeling and understanding of multimedia data, which...... largely refers to text, images/video, audio and combinations of such data. We review a number of applications within single and combined media with the hope that this might provide inspiration for further research in this area. Finally, we provide a detailed presentation of our own recent work on modeling...... combined text/image data for the purpose of cross-media retrieval....

  11. Map images portraying flight paths of low-altitude transects over the Arctic Network of national park units and Selawik National Wildlife Refuge, Alaska, July 2013

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Maps portraying the flight paths for low altitude transects conducted from small aircraft over the National Park Service’s Arctic Network (Bering Land Bridge...

  12. Garmin GPS waypoints delineating low-altitude transects over the Arctic Network of national park units and Selawik National Wildlife Refuge, Alaska, July 2013

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — GPS waypoints delineating the flight paths for low altitude transects from a Garmin GPS unit. Transects were conducted from small aircraft over the National Park...

  13. A Simulation Model for Component Commonality

    Institute of Scientific and Technical Information of China (English)

    ZHU Xiao-chi; ZHANG Zi-gang

    2002-01-01

    Component commonality has been cited as a powerful approach for manufacturers to cope with increased component proliferation and to control inventory costs. To fully realize its potential benefits, one needs a clear understanding of its impacts on the system. In this paper, the feasibility of using a simulation model to provide a systematic perspective for manufacturing firms to implement a commonality strategy is demonstrated. Alternative commonality strategies including the stage of employing commonality and the allocation policies are simulated. Several interesting results on effects of commonality, allocation policies,and optimal solutions are obtained. We then summarize qualitative insights and managerial implications into the component commonality design and implementation, and inventory management in a general multi-stage assembly system.

  14. Genetic Variation ofEPAS1Gene in Tibetan Pigs and ThreeLow-Altitude Pig Breeds in China

    Institute of Scientific and Technical Information of China (English)

    DONG Kun-zhe; KANG Ye; YAO Na; SHU Guo-tao; ZUO Qing-qing; ZHAO Qian-jun; MA Yue-hui

    2014-01-01

    Endothelial PAS domain protein 1 (EPAS1), also called hypoxia-inducible factor-2, is a key regulatory factor of hypoxic responses and plays an essential role in high-altitude adaptation in mammalian species. In this study, polymorphisms of EPAS1 were detected in 217 individuals from 2 Tibetan pig populations and 3 low-altitude pig breeds by DNA pooling, PCR-SSCP, PCR-RFLP and DNA sequencing methods. A total of 14 synonymous polymorphisms were identiifed in the coding region. The analysis suggested that SNP1 (G963A), SNP7 (C1632T), SNP10 (G1929A) and SNP11 (G1947A) showed potential association with high-altitude environment because of their particular variation patterns in Tibetan pigs. Linkage disequilibrium (LD) of these SNPs was analyzed. One common LD block including 5 SNPs clustering in exon 12 was identiifed in all studied pig populations. Haplotype H1 (AGGTC) in LD block was dominant in Tibetan pigs (76.6 and 74.2% in Linzhi (LZ) and Chayu (CY) pigs, respectively) and segregated at higher frequency than that in low-altitude pig breeds (52.3, 58.7 and 56.2% in Wuzhishan (WZS), Min (M) and Laiwu (LW) pigs, respectively), indicating that H1 may relate to adaptation to high altitude in Tibetan pigs. These ifndings raise hope thatEPAS1gene can be a candidate gene that involved in adaptation of high altitude in Tibetan pigs.

  15. Pool scrubbing models for iodine components

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, K. [Battelle Ingenieurtechnik GmbH, Eschborn (Germany)

    1996-12-01

    Pool scrubbing is an important mechanism to retain radioactive fission products from being carried into the containment atmosphere or into the secondary piping system. A number of models and computer codes has been developed to predict the retention of aerosols and fission product vapours that are released from the core and injected into water pools of BWR and PWR type reactors during severe accidents. Important codes in this field are BUSCA, SPARC and SUPRA. The present paper summarizes the models for scrubbing of gaseous Iodine components in these codes, discusses the experimental validation, and gives an assessment of the state of knowledge reached and the open questions which persist. The retention of gaseous Iodine components is modelled by the various codes in a very heterogeneous manner. Differences show up in the chemical species considered, the treatment of mass transfer boundary layers on the gaseous and liquid sides, the gas-liquid interface geometry, calculation of equilibrium concentrations and numerical procedures. Especially important is the determination of the pool water pH value. This value is affected by basic aerosols deposited in the water, e.g. Cesium and Rubidium compounds. A consistent model requires a mass balance of these compounds in the pool, thus effectively coupling the pool scrubbing phenomena of aerosols and gaseous Iodine species. Since the water pool conditions are also affected by drainage flow of condensate water from different regions in the containment, and desorption of dissolved gases on the pool surface is determined by the gas concentrations above the pool, some basic limitations of specialized pool scrubbing codes are given. The paper draws conclusions about the necessity of coupling between containment thermal-hydraulics and pool scrubbing models, and proposes ways of further simulation model development in order to improve source term predictions. (author) 2 tabs., refs.

  16. Metabolic syndrome components in murine models.

    Science.gov (United States)

    Lawson, Heather A; Cheverud, James M

    2010-03-01

    Animal models have enriched understanding of the physiological basis of metabolic disorders and advanced identification of genetic risk factors underlying the metabolic syndrome (MetS). Murine models are especially appropriate for this type of research, and are an excellent resource not only for identifying candidate genomic regions, but also for illuminating the possible molecular mechanisms or pathways affected in individual components of MetS. In this review, we briefly discuss findings from mouse models of metabolic disorders, particularly in light of issues raised by the recent flood of human genome-wide association studies (GWAS) results. We describe how mouse models are revealing that genotype interacts with environment in important ways, indicating that the underlying genetics of MetS is highly context dependant. Further we show that epistasis, imprinting and maternal effects each contribute to the genetic architecture underlying variation in metabolic traits, and mouse models provide an opportunity to dissect these aspects of the genetic architecture that are difficult if not impossible to ascertain in humans. Finally we discuss how knowledge gained from mouse models can be used in conjunction with comparative genomic methods and bioinformatic resources to inform human MetS research.

  17. Increased Hypoxic Dose After Training at Low Altitude with 9h Per Night at 3000m Normobaric Hypoxia

    Directory of Open Access Journals (Sweden)

    Amelia J. Carr, Philo U. Saunders, Brent S. Vallance, Laura A. Garvican-Lewis, Christopher J. Gore

    2015-12-01

    Full Text Available This study examined effects of low altitude training and a live-high: train-low protocol (combining both natural and simulated modalities on haemoglobin mass (Hbmass, maximum oxygen consumption (VO2max, time to exhaustion, and submaximal exercise measures. Eighteen elite-level race-walkers were assigned to one of two experimental groups; lowHH (low Hypobaric Hypoxia: continuous exposure to 1380 m for 21 consecutive days; n = 10 or a combined low altitude training and nightly Normobaric Hypoxia (lowHH+NHnight: living and training at 1380 m, plus 9 h.night-1 at a simulated altitude of 3000 m using hypoxic tents; n = 8. A control group (CON; n = 10 lived and trained at 600 m. Measurement of Hbmass, time to exhaustion and VO2max was performed before and after the training intervention. Paired samples t-tests were used to assess absolute and percentage change pre and post-test differences within groups, and differences between groups were assessed using a one-way ANOVA with least significant difference post-hoc testing. Statistical significance was tested at p < 0.05. There was a 3.7% increase in Hbmass in lowHH+NHnight compared with CON (p = 0.02. In comparison to baseline, Hbmass increased by 1.2% (±1.4% in the lowHH group, 2.6% (±1.8% in lowHH+NHnight, and there was a decrease of 0.9% (±4.9% in CON. VO2max increased by ~4% within both experimental conditions but was not significantly greater than the 1% increase in CON. There was a ~9% difference in pre and post-intervention values in time to exhaustion after lowHH+NH-night (p = 0.03 and a ~8% pre to post-intervention difference (p = 0.006 after lowHH only. We recommend low altitude (1380 m combined with sleeping in altitude tents (3000 m as one effective alternative to traditional altitude training methods, which can improve Hbmass.

  18. Measurements of SEP events during 23 and 24 solar cycles by polar low altitude Russian space missions: use for calculations of ozone layer response

    Science.gov (United States)

    Myagkova, Irina; Krivolutsky, Alexei A.

    Powerful solar flares are the source of solar energetic particles (SEP), which strongly influence the near-Earth environment and Earth’s atmosphere. Solar particles penetrating into high latitudes in the Earth’s atmosphere during magnetically quiet periods, and into middle ones during main phase of magnetic storms, cause its ionization and transform of its chemical composition. The response of the ozone layer to additional NOx and HOx production in the middle atmosphere depends not only on SEP intensity, but also on solar particle spectrum and SEP penetration boundary, especially during periods of geomagnetic storms, when significant variations of polar caps sizes are observed. So modeling of the processes in the Earth’s atmosphere should be based on experimental data about flux and spectra of SEP and about their penetration boundary. Satellites with low altitude polar orbits (LEO) allow measurement of both dynamics of solar energetic particles and variations of penetration boundaries of the solar particles. Several Russian spacecraft were launched to low altitude polar (LEO) orbits during the second half of the 23rd solar activity cycle and at the beginning of the 24th cycle. Russian solar observatory CORONAS-F was launched to the orbit with the inclination of 82.5 (o) , initial altitude 500 km and the final one of 350 km, on July 31, 2001, and it was operated until December 12, 2005. Its orbital period was about 94.8 minutes. Protons (1-90 MeV) and electrons (0.3-12 MeV) were measured by semiconductor and plastic scintillator detectors. The "Universitetskiy-Tatiana" satellite was launched to the orbit with the inclination of 83 (o) , altitude 1000 km, on January 20, 2005, and it was operated until March 8, 2007.For the monitoring of radiation conditions near the Earth the data on protons(2-100 MeV) and electrons (0.07-0.9 MeV), obtained by the semiconductor detector and the scintillation detector were used. «METEOR-M №1» has a polar solar

  19. Damage modelling in Plasma Facing Components

    Energy Technology Data Exchange (ETDEWEB)

    Martin, E.; Camus, G. [Bordeaux-1 Univ. des Sciences et Technologies-3, LCTS, Lab. des Composites Thermostructuraux, CNRS-UMR 5801, 33 - Pessac, (France); Schlosser, J. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    2007-07-01

    Full text of publication follows: The plasma facing components (PFC) of controlled fusion devices are submitted to high heat fluxes in operating conditions (10 MW/m2 for Tore Supra and up to 20 MW/m{sup 2} for ITER, Cadarache, France). Active cooling is required to maintain a reasonable surface temperature and to avoid critical heat flux and melting of the components. The PFC developed for Tore Supra are made of a carbon/carbon (C/C) composite flat tile bonded to a copper alloy heat sink. Under operating conditions, because of the thermal expansion mismatch existing between the C/C composite and the copper alloy, these components withstand significant stresses which induce damage in the C/C material as well as at the copper/composite interface. Design tools are thus required in order to analyse the initiation and the propagation of damage in thermally loaded PFC. The present study describes a modelling approach aimed at predicting damage in actively cooled PFC. For this purpose, dedicated experimental procedures have been developed and sound constitutive laws taking into account the damage related non linear behaviour of both the C/C material and the Cu-C/C joint have been established. Various tests have first been performed on C/C samples in tension and compression, within the fibre axis and off-axis, as well as in shear using a Iosipescu type device, in order to carefully analyse the non-linear mechanical behaviour of this material. A constitutive law able to handle complex multiaxial loadings, established within a classical thermodynamical framework and using scalar damage variables, was then identified. Tensile and shear tests were also performed on C/C-Cu samples in order to identify a cohesive zone model representative of the damageable behaviour of the joint. These constitutive laws were then introduced in a numerical model representative of a PFC. Obtained results have evidenced the progressive development of damage which takes place in the assembly when

  20. Food composition of some low altitude Lissotriton montandoni (Amphibia, Caudata populations from North-Western Romania

    Directory of Open Access Journals (Sweden)

    Covaciu-Marcov S.D.

    2010-01-01

    Full Text Available The diet of some populations of Lissotriton montandoni from north-western Romania is composed of prey belonging to 20 categories. The food components of the Carpathian newts are similar to those of other species of newts. Most of the prey are aquatic animals, but terrestrial prey also has a high percentage abundance. The consumed prey categories are common in the newts' habitats as well, but in natural ponds the prey item with the highest abundance in the diet is not the most frequent one in the habitat. Thus, although the Carpathian newts are basically opportunistic predators, they still display a certain trophic selectivity.

  1. Integration of Simulink Models with Component-based Software Models

    DEFF Research Database (Denmark)

    Marian, Nicolae

    2008-01-01

    constructs and process flow, then software code is generated. A Simulink model is a representation of the design or implementation of a physical system that satisfies a set of requirements. A software component-based system aims to organize system architecture and behaviour as a means of computation...... constraints. COMDES (Component-based Design of Software for Distributed Embedded Systems) is such a component-based system framework developed by the software engineering group of Mads Clausen Institute for Product Innovation (MCI), University of Southern Denmark. Once specified, the software model has......Model based development aims to facilitate the development of embedded control systems by emphasizing the separation of the design level from the implementation level. Model based design involves the use of multiple models that represent different views of a system, having different semantics...

  2. Strong localized variations of the low-altitude energetic electron fluxes in the evening sector near the plasmapause

    Directory of Open Access Journals (Sweden)

    E. E. Titova

    Full Text Available Specific type of energetic electron precipitation accompanied by a sharp increase in trapped energetic electron flux are found in the data obtained from low-altitude NOAA satellites. These strongly localized variations of the trapped and precipitated energetic electron flux have been observed in the evening sector near the plasmapause during recovery phase of magnetic storms. Statistical characteristics of these structures as well as the results of comparison with proton precipitation are described. We demonstrate the spatial coincidence of localized electron precipitation with cold plasma gradient and whistler wave intensification measured on board the DE-1 and Aureol-3 satellites. A simultaneous localized sharp increase in both trapped and precipitating electron flux could be a result of significant pitch-angle isotropization of drifting electrons due to their interaction via cyclotron instability with the region of sharp increase in background plasma density.

    Key words. Ionosphere (particle precipitation; wave-particle interaction Magnetospheric Physics (plasmasphere

  3. A Void Reference Sensor-Multiple Signal Classification Algorithm for More Accurate Direction of Arrival Estimation of Low Altitude Target

    Institute of Scientific and Technical Information of China (English)

    XIAO Hui; SUN Jin-cai; YUAN Jun; NIU Yi-long

    2007-01-01

    There exists MUSIC (multiple signal classification) algorithm for direction of arrival (DOA) estimation. This paper is to present a different MUSIC algorithm for more accurate estimation of low altitude target. The possibility of better performance is analyzed using a void reference sensor (VRS) in MUSIC algorithm. The following two topics are discussed: 1) the time delay formula and VRS-MUSIC algorithm with VRS located on the minus of z-axes; 2) the DOA estimation results of VRS-MUSIC and MUSIC algorithms. The simulation results show VRS-MUSIC algorithm has three advantages compared with MUSIC: 1 ) When the signal to noise ratio (SNR) is more than - 5 dB, the direction estimation error is 1/2 as much as that obtained by MUSIC; 2) The side lobe is more lower and the stability is better; 3) The size of array that the algorithm requires is smaller.

  4. Two-dimensional direction finding for low altitude target based on intensity measurement using an acoustic vector-sensor

    Institute of Scientific and Technical Information of China (English)

    CHEN Huawei; ZHAO Junwei

    2004-01-01

    A method of two-dimensional direction of arrival (DOA) estimation for low altitude target, which is based on intensity measurement using a three-dimensional differential pressure acoustic vector-sensor, is presented. With the perfect characteristics of acoustic vector sensor in the low frequency band, accurate DOA estimation is achieved under small array size. The validity of the proposed method was assessed by experiments on the noise signals radiated by a helicopter. The influence of acoustic sensor size, integral time and signal to noise ratio to the accuracy of DOA estimation were investigated, respectively. The performance comparisons demonstrated that it outperformed the traditional time-delay measurement based method for a small acoustic array.

  5. Global variations in regolith properties on asteroid Vesta from Dawn's low-altitude mapping orbit

    Science.gov (United States)

    Denevi, Brett W.; Beck, Andrew W.; Coman, Ecaterina I.; Thomson, Bradley J.; Ammannito, Eleonora; Blewett, David T.; Sunshine, Jessica M.; de Sanctis, Maria Cristina; Li, Jian-Yang; Marchi, Simone; Mittlefehldt, David W.; Petro, Noah E.; Raymond, Carol A.; Russell, Christopher T.

    2016-12-01

    We investigate the depth, variability, and history of regolith on asteroid Vesta using data from the Dawn spacecraft. High-resolution (15-20 m pixel-1) Framing Camera images are used to assess the presence of morphologic indicators of a shallow regolith, including the presence of blocks in crater ejecta, spur-and-gully-type features in crater walls, and the retention of small (chondrite material. The presence of a thick regolith in this area supports the idea that this is an ancient terrain that has accumulated a larger component of exogenic debris. We find evidence for the gardening of crater ejecta toward more howarditic compositions, consistent with regolith mixing being the dominant form of "weathering" on Vesta.

  6. High-Resolution 3D Bathymetric Mapping for Small Streams Using Low-Altitude Aerial Photography

    Science.gov (United States)

    Dietrich, J. T.; Duffin, J.

    2015-12-01

    Geomorphic monitoring of river restoration projects is a critical component of measuring their success. In smaller streams, with depths less than 2 meters, one of the more difficult variables to map at high-resolution is bathymetry. In larger rivers, bathymetry can be measured with instruments like multi-beam sonar, bathymetric airborne LiDAR, or acoustic doppler current profilers (ADCP). However, these systems are often limited by their minimum operating depths, which makes them ineffective in shallow water. Remote sensing offers several potential solutions for collecting bathymetry, spectral depth mapping and photogrammetric measurement (e.g. Structure-from-Motion (SfM) multi-view photogrammetry). In this case study, we use SfM to produce both high-resolution above water topography and below water bathymetry for two reaches of a stream restoration project on the Middle Fork of the John Day River in eastern Oregon and one reach on the White River in Vermont. We collected low-allitude multispectral (RGB+NIR) aerial photography at all of the sites at altitudes of 30 to 50 meters. The SfM survey was georeferenced with RTK-GPS ground control points and the bathymetry was refraction-corrected using additional RTK-GPS sample points. The resulting raster data products have horizontal resolutions of ~4-8 centimeters for the topography and ~8-15 cm for the bathymetry. This methodology, like many fluvial remote sensing methods, will only work under ideal conditions (e.g. clear water), but it provides an additional tool for collecting high-resolution bathymetric datasets for geomorphic monitoring efforts.

  7. The GNSS-R Eddy Experiment I: Altimetry from Low Altitude Aircraft

    CERN Document Server

    Ruffini, G; Caparrini, M; Germain, O; Martin-Neira, M

    2003-01-01

    We report results from the Eddy Experiment, where a synchronous GPS receiver pair was flown on an aircraft to collect sampled L1 signals and their reflections from the sea surface to investigate the altimetric accuracy of GNSS-R. During the experiment, surface wind speed (U10) was of the order of 10 m/s, and significant wave heights of up to 2 m, as discussed further in a companion paper. After software tracking of the two signals through despreading of the GPS codes, a parametric waveform model containing the description of the sea surface conditions has been used to fit the waveforms (retracking) and estimate the temporal lapse between the direct GPS signals and their reflections. The estimated lapses have then been used to estimate the sea surface height (SSH) along the aircraft track using a differential geometric model. As expected, the precision of GNSS-R ranges was of 3 m after 1 second integration. More importantly, the accuracy of the GNSS-R altimetric solution with respect to Jason-1 SSH and in situ...

  8. Integration of Simulink Models with Component-based Software Models

    DEFF Research Database (Denmark)

    Marian, Nicolae; Top, Søren

    2008-01-01

    of abstract system descriptions. Usually, in mechatronics systems, design proceeds by iterating model construction, model analysis, and model transformation. Constructing a MATLAB/Simulink model, a plant and controller behavior is simulated using graphical blocks to represent mathematical and logical...... of MATLAB/Simulink blocks to COMDES software components, both for continuous and discrete behaviour, and the transformation of the software system into the S-functions. The general aim of this work is the improvement of multi-disciplinary development of embedded systems with the focus on the relation...... constructs and process flow, then software code is generated. A Simulink model is a representation of the design or implementation of a physical system that satisfies a set of requirements. A software component-based system aims to organize system architecture and behaviour as a means of computation...

  9. Hydrologic validation of a structure-from-motion DEM derived from low-altitude UAV imagery

    Science.gov (United States)

    Steiner, Florian; Marzolff, Irene; d'Oleire-Oltmanns, Sebastian

    2015-04-01

    The increasing ease of use of current Unmanned Aerial Vehicles (UAVs) and 3D image processing software has spurred the number of applications relying on high-resolution topographic datasets. Of particular significance in this field is "structure from motion" (SfM), a photogrammetric technique used to generate low-cost digital elevation models (DEMs) for erosion budgeting, measuring of glaciers/lava-flows, archaeological applications and others. It was originally designed to generate 3D-models of buildings, based on unordered collections of images and has become increasingly common in geoscience applications during the last few years. Several studies on the accuracy of this technique already exist, in which the SfM data is mostly compared with Lidar-generated terrain data. The results are mainly positive, indicating that the technique is suitable for such applications. This work aims at validating very high resolution SfM DEMs with a different approach: Not the original elevation data is validated, but data on terrain-related hydrological and geomorphometric parameters derived from the DEM. The study site chosen for this analysis is an abandoned agricultural field near the city of Taroudant, in the semi-arid southern part of Morocco. The site is characterized by aggressive rill and gully erosion and is - apart from sparsely scattered shrub cover - mainly featureless. An area of 5.7 ha, equipped with 30 high-precision ground control points (GCPs), was covered with an unmanned aerial vehicle (UAV) in two different heights (85 and 170 m). A selection of 160 images was used to generate several high-resolution DEMs (2 and 5 cm resolution) of the area using the fully automated SfM software AGISOFT Photoscan. For comparison purposes, a conventional photogrammetry-based workflow using the Leica Photogrammetry Suite was used to generate a DEM with a resolution of 5 cm (LPS DEM). The evaluation is done by comparison of the SfM DEM with the derived orthoimages and the LPS DEM

  10. Radioisotope Stirling Engine Powered Airship for Low Altitude Operation on Venus

    Science.gov (United States)

    Colozza, Anthony J.

    2012-01-01

    The feasibility of a Stirling engine powered airship for the near surface exploration of Venus was evaluated. The heat source for the Stirling engine was limited to 10 general purpose heat source (GPHS) blocks. The baseline airship utilized hydrogen as the lifting gas and the electronics and payload were enclosed in a cooled insulated pressure vessel to maintain the internal temperature at 320 K and 1 Bar pressure. The propulsion system consisted of an electric motor driving a propeller. An analysis was set up to size the airship that could operate near the Venus surface based on the available thermal power. The atmospheric conditions on Venus were modeled and used in the analysis. The analysis was an iterative process between sizing the airship to carry a specified payload and the power required to operate the electronics, payload and cooling system as well as provide power to the propulsion system to overcome the drag on the airship. A baseline configuration was determined that could meet the power requirements and operate near the Venus surface. From this baseline design additional trades were made to see how other factors affected the design such as the internal temperature of the payload chamber and the flight altitude. In addition other lifting methods were evaluated such as an evacuated chamber, heated atmospheric gas and augmented heated lifting gas. However none of these methods proved viable.

  11. Stable Imaging and Accuracy Issues of Low-Altitude Unmanned Aerial Vehicle Photogrammetry Systems

    Directory of Open Access Journals (Sweden)

    Ying Yang

    2016-04-01

    Full Text Available Stable imaging of an unmanned aerial vehicle (UAV photogrammetry system is an important issue that affects the data processing and application of the system. Compared with traditional aerial images, the large rotation of roll, pitch, and yaw angles of UAV images decrease image quality and result in image deformation, thereby affecting the ground resolution, overlaps, and the consistency of the stereo models. These factors also cause difficulties in automatic tie point matching, image orientation, and accuracy of aerial triangulation (AT. The issues of large-angle photography of UAV photogrammetry system are discussed and analyzed quantitatively in this paper, and a simple and lightweight three-axis stabilization platform that works with a low-precision integrated inertial navigation system and a three-axis mechanical platform is used to reduce this problem. An experiment was carried out with an airship as the flight platform. Another experimental dataset, which was acquired by the same flight platform without a stabilization platform, was utilized for a comparative test. Experimental results show that the system can effectively isolate the swing of the flying platform. To ensure objective and reliable results, another group of experimental datasets, which were acquired using a fixed-wing UAV platform, was also analyzed. Statistical results of the experimental datasets confirm that stable imaging of a UAV platform can help improve the quality of aerial photography imagery and the accuracy of AT, and potentially improve the application of images acquired by a UAV.

  12. Low-Altitude Reconnection Inflow-Outflow Observations during a 2010 November 3 Eruption

    CERN Document Server

    Savage, S L; Reeves, K K; Seaton, D B; McKenzie, D E; Su, Y

    2011-01-01

    For a flare occurring on 2010 November 3, we present observations using several SDO/AIA extreme-ultraviolet (EUV) passbands of an erupting filament followed by inflows sweeping into a current sheet region. The inflows are soon followed by outflows appearing to originate from near the termination point of the inflowing motion - an observation in line with standard magnetic reconnection models. We measure average inflow plane-of-sky speeds to range from ~150-690 km/s with the initial, high-temperature inflows being the fastest. Using the inflow speeds and a range of Alfven speeds, we estimate the Alfvenic Mach number which appears to decrease with time. We also provide inflow and outflow times with respect to RHESSI count rates and find that the fast, high-temperature inflows occur simultaneously with a peak in the RHESSI thermal lightcurve. Five candidate inflow-outflow pairs are identified with no more than a minute delay between detections. The inflow speeds of these pairs are measured to be 10^2 km/s with o...

  13. 基于3S 技术的低空空域告警航图可视化匹配设计初探%Primary exploration of 3S technology in the matching design of visual alarm chart in low altitude airspace

    Institute of Scientific and Technical Information of China (English)

    冯登超; 秦焕禹; 曾湧

    2015-01-01

    In the paper ,3S technology was applied to the warning chart visualization design in the low altitude airspace , the route of the low altitude warning chart platform and low alarm chart matching model were explored .According to the different requirements and emergency degree of mission ,multi‐source remote sensing data with appropriate spatial reso‐lution was selected .The information of geographical obstacle was filtered ,the database of low altitude warning chart ob‐stacle was built ,and the low altitude airspace warning chart platform was designed .Aircraft airborne positioning system was used to collect the aircraft position information ,and the low altitude warning special obstacle information chart was compared with .Aircraft flying in a dangerous situation can be warned early .The RS ,GIS ,GNSS technology (3S tech‐nology) is applied in the design of visual chart in low altitude airspace warning ,which can provide the reference for the flight scene matching research in low altitude airspace .%将3S技术应用于低空空域告警航图可视化设计,探索建立低空告警航图平台和低空告警航图匹配模型的技术路线。根据低空飞行任务需求和紧急程度选择适当空间分辨率的多源遥感数据。对地理障碍物信息进行筛选,构建低空告警航图障碍物数据库,设计低空空域告警航图平台。使用飞行器机载定位系统采集飞行器位置信息,与低空告警专用航图障碍物信息进行对比,对低空飞行危险情况预警,将RS、GIS、GNSS技术应用于低空空域告警航图可视化设计,为后续开展低空空域告警航图可视化的飞行视景匹配研究提供参考。

  14. High resolution three-dimensional magnetization mapping in Tokachidake Volcano using low altitude airborne magnetic survey data

    Science.gov (United States)

    Iwata, M.; Mogi, T.; Okuma, S.; Nakatsuka, T.

    2016-12-01

    Tokachidake Volcano, central Hokkaido, Japan erupted in 1926, 1962 and 1988-1989 in the 20th century from the central part. In recent years, expansions of the edifice of the volcano at shallow depth and increases of the volcanic smoke in the Taisho crater were observed (Meteorological Agency of Japan, 2014). Magnetic changes were observed at the 62-2 crater by repeated magnetic measurements in 2008-2009, implying a demagnetization beneath the crater (Hashimoto at al., 2010). Moreover, a very low resistivity part was found right under the 62-2 crater from an AMT survey (Yamaya et al., 2010). However, since the station numbers of the survey are limited, the area coverage is not sufficient. In this study, we have re-analyzed high-resolution aeromagnetic data to delineate the three-dimensional magnetic structure of the volcano to understand the nature of other craters.A low altitude airborne magnetic survey was conducted in 2014 mainly over the active areas of the volcano by the Ministry of Land, Infrastructure, Transport and Tourism to manage land slide risk in the volcano. The survey was flown at an altitude of 60 m above ground by a helicopter with a Cesium magnetometer in the towed-bird 30m below the helicopter. The low altitude survey enables us to delineate the detailed magnetic structure. We calculated magnetic anomaly distribution on a smooth surface assuming equivalent anomalies below the observation surface. Then the 3D magnetic imaging method (Nakatsuka and Okuma, 2014) was applied to the magnetic anomalies to reveal the three-dimensional magnetic structure.As a result, magnetization highs were seen beneath the Ground crater, Suribachi crater and Kitamuki crater. This implies that magmatic activity occurred in the past at these craters. These magma should have already solidified and acquired strong remanent magnetization. Relative magnetization lows were seen beneath the 62-2 crater and the Taisho crater where fumarolic activity is active. However a

  15. How Many Separable Sources? Model Selection In Independent Components Analysis

    DEFF Research Database (Denmark)

    Woods, Roger P.; Hansen, Lars Kai; Strother, Stephen

    2015-01-01

    Unlike mixtures consisting solely of non-Gaussian sources, mixtures including two or more Gaussian components cannot be separated using standard independent components analysis methods that are based on higher order statistics and independent observations. The mixed Independent Components Analysi...... might otherwise be questionable. Failure of the Akaike Information Criterion in model selection also has relevance in traditional independent components analysis where all sources are assumed non-Gaussian.......Unlike mixtures consisting solely of non-Gaussian sources, mixtures including two or more Gaussian components cannot be separated using standard independent components analysis methods that are based on higher order statistics and independent observations. The mixed Independent Components Analysis....../Principal Components Analysis (mixed ICA/PCA) model described here accommodates one or more Gaussian components in the independent components analysis model and uses principal components analysis to characterize contributions from this inseparable Gaussian subspace. Information theory can then be used to select from...

  16. Semantic network based component organization model for program mining

    Institute of Scientific and Technical Information of China (English)

    王斌; 张尧学; 陈松乔

    2003-01-01

    Based on the definition of component ontology, an effective component classification mechanism and a facet named component relationship are proposed. Then an application domain oriented, hierarchical component organization model is established. At last a hierarchical component semantic network (HCSN) described by ontology interchange language(OIL) is presented and then its function is described. Using HCSN and cooperating with other components retrieving algorithms based on component description, other components information and their assembly or composite modes related to the key component can be found. Based on HCSN, component directory library is catalogued and a prototype system is constructed. The prototype system proves that component library organization based on this model gives guarantee to the reliability of component assembly during program mining.

  17. Applications of low altitude remote sensing in agriculture upon farmers' requests--a case study in northeastern Ontario, Canada.

    Science.gov (United States)

    Zhang, Chunhua; Walters, Dan; Kovacs, John M

    2014-01-01

    With the growth of the low altitude remote sensing (LARS) industry in recent years, their practical application in precision agriculture seems all the more possible. However, only a few scientists have reported using LARS to monitor crop conditions. Moreover, there have been concerns regarding the feasibility of such systems for producers given the issues related to the post-processing of images, technical expertise, and timely delivery of information. The purpose of this study is to showcase actual requests by farmers to monitor crop conditions in their fields using an unmanned aerial vehicle (UAV). Working in collaboration with farmers in northeastern Ontario, we use optical and near-infrared imagery to monitor fertilizer trials, conduct crop scouting and map field tile drainage. We demonstrate that LARS imagery has many practical applications. However, several obstacles remain, including the costs associated with both the LARS system and the image processing software, the extent of professional training required to operate the LARS and to process the imagery, and the influence from local weather conditions (e.g. clouds, wind) on image acquisition all need to be considered. Consequently, at present a feasible solution for producers might be the use of LARS service provided by private consultants or in collaboration with LARS scientific research teams.

  18. Low altitude energetic electron lifetimes after enhanced magnetic activity as deduced from SAC-C and DEMETER data

    Directory of Open Access Journals (Sweden)

    S. Benck

    2010-03-01

    Full Text Available When flux enhancements of energetic electrons are produced as a consequence of geomagnetic storm occurrence, they tend to vanish gradually when the magnetic activity calms down and the fluxes decay to quiet-time levels. We use SAC-C and DEMETER low altitude observations to estimate the energetic electron lifetimes (E=0.16–1.4 MeV, L=1.6–5, B=0.22–0.46 G and compare the decay rates to those observed at high altitude. While crossing the radiation belts at high latitude, the SAC-C and DEMETER instruments sample particles with small equatorial pitch angles (αeq<18° for L>2.5 whereas the comparison is done with other satellite data measured mainly in the equatorial plane (for αeq>75°. While in the inner belt and in the slot region no significant lifetime differences are observed from the data sets with different αeq, in the outer belt, for the least energetic electrons (<500 keV, the lifetimes are up to ~3 times larger for the electrons with the equatorial pitch-angle close to the loss cone than for those mirroring near the equator. The difference decreases with increasing energy and vanishes for energies of about 1 MeV.

  19. Piloted Simulation of Various Synthetic Vision Systems Terrain Portrayal and Guidance Symbology Concepts for Low Altitude En-Route Scenario

    Science.gov (United States)

    Takallu, M. A.; Glaab, L. J.; Hughes, M. F.; Wong, D. T.; Bartolone, A. P.

    2008-01-01

    In support of the NASA Aviation Safety Program's Synthetic Vision Systems Project, a series of piloted simulations were conducted to explore and quantify the relationship between candidate Terrain Portrayal Concepts and Guidance Symbology Concepts, specific to General Aviation. The experiment scenario was based on a low altitude en route flight in Instrument Metrological Conditions in the central mountains of Alaska. A total of 18 general aviation pilots, with three levels of pilot experience, evaluated a test matrix of four terrain portrayal concepts and six guidance symbology concepts. Quantitative measures included various pilot/aircraft performance data, flight technical errors and flight control inputs. The qualitative measures included pilot comments and pilot responses to the structured questionnaires such as perceived workload, subjective situation awareness, pilot preferences, and the rare event recognition. There were statistically significant effects found from guidance symbology concepts and terrain portrayal concepts but no significant interactions between them. Lower flight technical errors and increased situation awareness were achieved using Synthetic Vision Systems displays, as compared to the baseline Pitch/Roll Flight Director and Blue Sky Brown Ground combination. Overall, those guidance symbology concepts that have both path based guidance cue and tunnel display performed better than the other guidance concepts.

  20. 75 FR 47252 - Proposed Establishment of Low Altitude Area Navigation Routes (T-281, T-283, T-285, T-286, and T...

    Science.gov (United States)

    2010-08-05

    ... Altitude Area Navigation Routes (T- 281, T-283, T-285, T-286, and T-288); Nebraska and South Dakota AGENCY... action proposes to establish five low altitude Area Navigation (RNAV) routes, designated T-281, T-283, T-285, T-286, and T- 288, over Nebraska and South Dakota; controlled by Denver Air Route Traffic...

  1. Nadir videos taken during low-altitude transects of the Arctic Network of national park units and Selawik National Wildlife Refuge, Alaska, July 2013

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Nadir videos shot from a GoPro Hero3 Black Edition (focal length 2.77 mm) of the arctic landscape during low altitude transects at the rate of 60 frames per second....

  2. Accurate modelling of UV written waveguide components

    DEFF Research Database (Denmark)

    Svalgaard, Mikael

    BPM simulation results of UV written waveguide components that are indistinguishable from measurements can be achieved on the basis of trajectory scan data and an equivalent step index profile that is very easy to measure.......BPM simulation results of UV written waveguide components that are indistinguishable from measurements can be achieved on the basis of trajectory scan data and an equivalent step index profile that is very easy to measure....

  3. Accurate modeling of UV written waveguide components

    DEFF Research Database (Denmark)

    Svalgaard, Mikael

    BPM simulation results of UV written waveguide components that are indistinguishable from measurements can be achieved on the basis of trajectory scan data and an equivalent step index profile that is very easy to measure.......BPM simulation results of UV written waveguide components that are indistinguishable from measurements can be achieved on the basis of trajectory scan data and an equivalent step index profile that is very easy to measure....

  4. Distribution and abundance of forest birds in low-altitude habitat on Hawai'i Island: Evidence for range expansion of native species

    Science.gov (United States)

    Spiegel, C.S.; Hart, P.J.; Woodwort, B.L.; Tweed, E.J.; Leburn, J.J.

    2006-01-01

    The Hawaiian honeycreepers are thought to be limited primarily to middle- and high-altitude wet forests due to anthropogenic factors at lower altitudes, especially introduced mosquitotransmitted avian malaria. However, recent research has demonstrated that at least one native species, the Hawai'i 'Amakihi (Hemignathus virens virens), is common in areas of active malaria transmission. We examined the current distribution and abundance of native and exotic forest birds within approximately 640 km2 of low-altitude (0-326 m) habitat on south-eastern Hawai'i Island, using roadside variable circular plot (VCP) at 174 stations along eight survey transects. We also re-surveyed 90 stations near sea level that were last surveyed in 1994-1995. Overall, introduced species were more abundant than natives; 11 exotic species made up 87% of the total individuals detected. The most common exotic passerines were Japanese White-eye (Zosterops japonicus), House Finch (Carpodacus mexicanus) and Northern Cardinal (Cardinalis cardinalis). Two native species, Hawai'i 'Amakihi and 'Apapane (Himatione sanguina), comprised 13% of the bird community at low altitudes. Hawai'i 'Amakihi were the most common and widespread native species, being found at 47% of stations at a density of 4.98 birds/ha (95% CI 3.52-7.03). Amakihi were significantly associated with 'ohi'a (Metrosideros polymorpha)-dominated forest. 'Apapane were more locally distributed, being found at only 10% of stations. Re-surveys of 1994-1995 transects demonstrated a significant increase in 'Amakihi abundance over the past decade. This work demonstrates a widespread recovery of Hawai'i 'Amakihi at low altitude in southeastern Hawai'i. The changing composition of the forest bird community at low-altitudes in Hawai'i has important implications for the dynamics of avian malaria in low-altitude Hawai'i, and for conservation of Hawai'i's lowland forests. ?? 2006 BirdLife International.

  5. Component-based Discrete Event Simulation Using the Fractal Component Model

    OpenAIRE

    Dalle, Olivier

    2007-01-01

    In this paper we show that Fractal, a generic component model coming from the Component-Based Software Engineering (CBSE) community, meets most of the functional expectations identified so far in the simulation community for component-based modeling and simulation. We also demonstrate that Fractal offers additional features that have not yet been identified in the simulation community despite their potential usefulness. Eventually we describe our ongoing work on such a new simulation architec...

  6. Modelling, design and realization of microfluidic components

    NARCIS (Netherlands)

    Oosterbroek, R.E.

    1999-01-01

    During the last decades, miniaturization of electrical components and systems has assumed large proportions. The reason for these developments is the application of etch and deposition techniques in the IC-production (integrated circuit), which allows a large amount of functionality per surface

  7. Advanced Placement: Model Policy Components. Policy Analysis

    Science.gov (United States)

    Zinth, Jennifer

    2016-01-01

    Advanced Placement (AP), launched in 1955 by the College Board as a program to offer gifted high school students the opportunity to complete entry-level college coursework, has since expanded to encourage a broader array of students to tackle challenging content. This Education Commission of the State's Policy Analysis identifies key components of…

  8. Distributed micro-radar system for detection and tracking of low-profile, low-altitude targets

    Science.gov (United States)

    Gorwara, Ashok; Molchanov, Pavlo

    2016-05-01

    Proposed airborne surveillance radar system can detect, locate, track, and classify low-profile, low-altitude targets: from traditional fixed and rotary wing aircraft to non-traditional targets like unmanned aircraft systems (drones) and even small projectiles. Distributed micro-radar system is the next step in the development of passive monopulse direction finder proposed by Stephen E. Lipsky in the 80s. To extend high frequency limit and provide high sensitivity over the broadband of frequencies, multiple angularly spaced directional antennas are coupled with front end circuits and separately connected to a direction finder processor by a digital interface. Integration of antennas with front end circuits allows to exclude waveguide lines which limits system bandwidth and creates frequency dependent phase errors. Digitizing of received signals proximate to antennas allows loose distribution of antennas and dramatically decrease phase errors connected with waveguides. Accuracy of direction finding in proposed micro-radar in this case will be determined by time accuracy of digital processor and sampling frequency. Multi-band, multi-functional antennas can be distributed around the perimeter of a Unmanned Aircraft System (UAS) and connected to the processor by digital interface or can be distributed between swarm/formation of mini/micro UAS and connected wirelessly. Expendable micro-radars can be distributed by perimeter of defense object and create multi-static radar network. Low-profile, lowaltitude, high speed targets, like small projectiles, create a Doppler shift in a narrow frequency band. This signal can be effectively filtrated and detected with high probability. Proposed micro-radar can work in passive, monostatic or bistatic regime.

  9. Effect of atmospheric CO 2 enrichment on rubisco content in herbaceous species from high and low altitude

    Science.gov (United States)

    Sage, Rowan F.; Schäppi, Bernd; Körner, Christian

    Atmospheric CO 2 enrichment reduces Rubisco content in many species grown in controlled environments; however, relatively few studies have examined CO 2 effects on Rubisco content of plants grown in their natural habitat. We examined the response of Rubisco content to atmospheric CO 2 enrichment (600-680 μmol mol -1 in place of ppm) in 5 herbaceous species growing in a low altitude grassland (550 m) near Basel, Switzerland, and 3 herbaceous species from Swiss alpine grassland at 2470 m. At low elevation, the dominant grass Bromus erectus and the subdominant dicot Sanquisorba minor exhibited 20% to 25% reduction of Rubisco content following high CO 2 exposure; no CO 2 effect was observed in the subdominants Carex flacca, Lotus corniculatus and Trifolium repens. At the Alpine site, the subdominant grass Poa alpina maintained 27% less Rubisco content when grown at high CO 2 while the co-dominant forb Leontodon helveticus had 19% less Rubisco in high CO 2. Rubisco content was unaffected in the tundra dominant Carex curvula. Because the degree of Rubisco modulation was similar between high and low elevation sites, it does not appear that differences in local partial pressure of CO 2 (altitude) or differences in stress in general induce different patterns of modulation of photosynthetic capacity in response to high CO 2. In addition, the degree of Rubisco reduction (<30%) was less than might be indicated by the low biomass response to CO 2 enrichment previously observed at these sites. Thus, plants in Swiss lowland and alpine grassland appear to maintain greater Rubisco concentration and photosynthetic capacity than whole plants can effectively exploit in terms of harvestable biomass.

  10. Conjugate observations of a remarkable quasiperiodic event by the low-altitude DEMETER spacecraft and ground-based instruments

    Science.gov (United States)

    Němec, F.; Bezděková, B.; Manninen, J.; Parrot, M.; Santolík, O.; Hayosh, M.; Turunen, T.

    2016-09-01

    We present a detailed analysis of a long-lasting quasiperiodic (QP) event observed simultaneously by the low-altitude DEMETER spacecraft and on the ground by the instrumentation of the Sodankylä Geophysical Observatory, Finland. The event was observed on 26 February 2008. It lasted for several hours, and it was detected both in the Northern and Southern Hemispheres. The time intervals when the event was observed on board the satellite and/or on the ground provide us with an estimate of the event dimensions. When the event is detected simultaneously by the satellite and on the ground, the observed frequency-time structure is generally the same. However, the ratio of detected intensities varies significantly as a function of the spacecraft latitude, indicating the wave guiding along the plasmapause. Moreover, there is a delay as large as about 13 s between the times when individual QP elements are detected by the spacecraft and on the ground. This appears to be related to the azimuthal separation of the instruments, and it is highly relevant to the identification of a possible source mechanism. We suggest that it is due to an azimuthally propagating ULF wave which periodically modulates the azimuthally extended source region. Finally, we find that at the times when the intensity of the QP event suddenly increases, there is a distinct increase of the amplitude of Alfvénic ULF pulsations measured on the ground at high latitudes. This might indicate that the source region is located at L shells larger than about 7.1.

  11. Ecological Risk Assessment Framework for Low-Altitude Overflights by Fixed-Wing and Rotary-Wing Military Aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Efroymson, R.A.

    2001-01-12

    This is a companion report to the risk assessment framework proposed by Suter et al. (1998): ''A Framework for Assessment of Risks of Military Training and Testing to Natural Resources,'' hereafter referred to as the ''generic framework.'' The generic framework is an ecological risk assessment methodology for use in environmental assessments on Department of Defense (DoD) installations. In the generic framework, the ecological risk assessment framework of the US Environmental Protection Agency (EPA 1998) is modified for use in the context of (1) multiple and diverse stressors and activities at a military installation and (2) risks resulting from causal chains, e.g., effects on habitat that indirectly impact wildlife. Both modifications are important if the EPA framework is to be used on military installations. In order for the generic risk assessment framework to be useful to DoD environmental staff and contractors, the framework must be applied to specific training and testing activities. Three activity-specific ecological risk assessment frameworks have been written (1) to aid environmental staff in conducting risk assessments that involve these activities and (2) to guide staff in the development of analogous frameworks for other DoD activities. The three activities are: (1) low-altitude overflights by fixed-wing and rotary-wing aircraft (this volume), (2) firing at targets on land, and (3) ocean explosions. The activities were selected as priority training and testing activities by the advisory committee for this project.

  12. Probabilistic Modeling of Wind Turbine Drivetrain Components

    DEFF Research Database (Denmark)

    Rafsanjani, Hesam Mirzaei

    Wind energy is one of several energy sources in the world and a rapidly growing industry in the energy sector. When placed in offshore or onshore locations, wind turbines are exposed to wave excitations, highly dynamic wind loads and/or the wakes from other wind turbines. Therefore, most components....../nodules on fatigue life of cast iron samples. The cast iron samples scanned by 3D tomography equipment at the DTU Wind Energy (Risø campus), and the distribution of nodules are used to estimate the fatigue life....

  13. Component-based event composition modeling for CPS

    Science.gov (United States)

    Yin, Zhonghai; Chu, Yanan

    2017-06-01

    In order to combine event-drive model with component-based architecture design, this paper proposes a component-based event composition model to realize CPS’s event processing. Firstly, the formal representations of component and attribute-oriented event are defined. Every component is consisted of subcomponents and the corresponding event sets. The attribute “type” is added to attribute-oriented event definition so as to describe the responsiveness to the component. Secondly, component-based event composition model is constructed. Concept lattice-based event algebra system is built to describe the relations between events, and the rules for drawing Hasse diagram are discussed. Thirdly, as there are redundancies among composite events, two simplification methods are proposed. Finally, the communication-based train control system is simulated to verify the event composition model. Results show that the event composition model we have constructed can be applied to express composite events correctly and effectively.

  14. A Components Library System Model and the Support Tool

    Institute of Scientific and Technical Information of China (English)

    MIAO Huai-kou; LIU Hui; LIU Jing; LI Xiao-bo

    2004-01-01

    Component-based development needs a well-designed components library and a set of support tools.This paper presents the design and implementation of a components library system model and its support tool UMLCASE.A set of practical CASE tools is constructed.UMLCASE can use UML to design Use Case Diagram, Class Diagram etc.And it integrates with components library system.

  15. Current Flow and Pair Creation at Low Altitude in Rotation-Powered Pulsars' Force-Free Magnetospheres: Space Charge Limited Flow

    Science.gov (United States)

    Timokhin, A. N.; Arons, J.

    2013-01-01

    We report the results of an investigation of particle acceleration and electron-positron plasma generation at low altitude in the polar magnetic flux tubes of rotation-powered pulsars, when the stellar surface is free to emit whatever charges and currents are demanded by the force-free magnetosphere. We apply a new 1D hybrid plasma simulation code to the dynamical problem, using Particle-in-Cell methods for the dynamics of the charged particles, including a determination of the collective electrostatic fluctuations in the plasma, combined with a Monte Carlo treatment of the high-energy gamma-rays that mediate the formation of the electron-positron pairs.We assume the electric current flowing through the pair creation zone is fixed by the much higher inductance magnetosphere, and adopt the results of force-free magnetosphere models to provide the currents which must be carried by the accelerator. The models are spatially one dimensional, and designed to explore the physics, although of practical relevance to young, high-voltage pulsars. We observe novel behaviour (a) When the current density j is less than the Goldreich-Julian value (0 1), the system develops high voltage drops (TV or greater), causing emission of curvature gamma-rays and intense bursts of pair creation. The bursts exhibit limit cycle behaviour, with characteristic time-scales somewhat longer than the relativistic fly-by time over distances comparable to the polar cap diameter (microseconds). (c) In return current regions, where j/j(sub GJ) rotating frame), finding that such steady flows can occupy only a small fraction of the current density parameter space exhibited by the force-free magnetospheric model. The generic polar flow dynamics and pair creation are strongly time dependent. The model has an essential difference from almost all previous quantitative studies, in that we sought the accelerating voltage (with pair creation, when the voltage drops are sufficiently large; without, when they are

  16. Modeling thermally active building components using space mapping

    DEFF Research Database (Denmark)

    Pedersen, Frank; Weitzmann, Peter; Svendsen, Svend

    2005-01-01

    simplified models of the components do not always provide useful solutions, since they are not always able to reproduce the correct thermal behavior. The space mapping technique transforms a simplified, but computationally inexpensive model, in order to align it with a detailed model or measurements....... This paper describes the principle of the space mapping technique, and introduces a simple space mapping technique. The technique is applied to a lumped parameter model of a thermo active component, which provides a model of the thermal performance of the component as a function of two design parameters......In order to efficiently implement thermally active building components in new buildings, it is necessary to evaluate the thermal interaction between them and other building components. Applying parameter investigation or numerical optimization methods to a differential-algebraic (DAE) model...

  17. Three components model of enterprise’s export activity

    OpenAIRE

    S.A.-A. Al-Osta

    2015-01-01

    The article presents the export activity of the enterprise in the form of structural three components model. It is suggested to include to the model composition such components as pre-export, restructuring / adaptation and export operation. The nature of the given export activities components has been defined. A special role of adaptive changes in the conversion of pre-export to the export operation has been substantiated. The aim of the article. The article is aimed at forming an integrat...

  18. TESTS FOR VARIANCE COMPONENTS IN VARYING COEFFICIENT MIXED MODELS

    National Research Council Canada - National Science Library

    Zaixing Li; Yuedong Wang; Ping Wu; Wangli Xu; Lixing Zhu

    2012-01-01

    .... To address the question of whether a varying coefficient mixed model can be reduced to a simpler varying coefficient model, we develop one-sided tests for the null hypothesis that all the variance components are zero...

  19. Model-integrating software components engineering flexible software systems

    CERN Document Server

    Derakhshanmanesh, Mahdi

    2015-01-01

    In his study, Mahdi Derakhshanmanesh builds on the state of the art in modeling by proposing to integrate models into running software on the component-level without translating them to code. Such so-called model-integrating software exploits all advantages of models: models implicitly support a good separation of concerns, they are self-documenting and thus improve understandability and maintainability and in contrast to model-driven approaches there is no synchronization problem anymore between the models and the code generated from them. Using model-integrating components, software will be

  20. Stochastic Models for Common Failures of Components.

    Science.gov (United States)

    1984-03-01

    common cause model, NUREG /CR-1401, 1980. [3] Church, J. D. and Harris, B., The estimation of reliability from stress- strength relationship...Fachband 2/1, 1980. [11] Lewis, H. W., Chairman, Risk Assessment Review Group Report to the U. S. Nuclear Regulatory Commission, NUREG /CR-0400, 1978. [12...Regulatory Commission, P.R.A. Procedures Guide, NUREG / CR-2300, 1983. [18] Vesely, W. E., Estimating Common Cause Failure Probabilities in Reliability and

  1. Modeling the human prothrombinase complex components

    Science.gov (United States)

    Orban, Tivadar

    Thrombin generation is the culminating stage of the blood coagulation process. Thrombin is obtained from prothrombin (the substrate) in a reaction catalyzed by the prothrombinase complex (the enzyme). The prothrombinase complex is composed of factor Xa (the enzyme), factor Va (the cofactor) associated in the presence of calcium ions on a negatively charged cell membrane. Factor Xa, alone, can activate prothrombin to thrombin; however, the rate of conversion is not physiologically relevant for survival. Incorporation of factor Va into prothrombinase accelerates the rate of prothrombinase activity by 300,000-fold, and provides the physiological pathway of thrombin generation. The long-term goal of the current proposal is to provide the necessary support for the advancing of studies to design potential drug candidates that may be used to avoid development of deep venous thrombosis in high-risk patients. The short-term goals of the present proposal are to (1) to propose a model of a mixed asymmetric phospholipid bilayer, (2) expand the incomplete model of human coagulation factor Va and study its interaction with the phospholipid bilayer, (3) to create a homology model of prothrombin (4) to study the dynamics of interaction between prothrombin and the phospholipid bilayer.

  2. Numerical simulation of bistatic scattering from a target at low altitude above rough sea surface under an EM wave incidence at low grazing angle by using the finite element method

    Institute of Scientific and Technical Information of China (English)

    LIU Peng; JIN Yaqiu

    2004-01-01

    To study bistatic scattering from a target at low altitude above two- dimensional (2D) randomly rough sea surface under an electromagnetic (EM) wave incidence at low grazing angle (LGA), a numerical approach of the finite element method (FEM) is developed. The conformal perfectly matched layer (PML), as the truncation boundary of the FEM, is employed to reduce the reflection error of planar PML in conventional FEM. Numerical code of our FEM is examined by available solution of the forward backward iterative (FBM) method. Bistatic and back-scattering from composite model of a target above random rough sea surface generated by Monte Carlo realization, and functional dependence upon the sea surface wind speed, target altitude, incident and scattering angles, etc. are numerically simulated and discussed. This paper presents a numerical description of the observation principle and physical insight associated with the coupling interactions of a complex volumetric target and random rough sea surface.

  3. The elasto-damage theory of the components assembling model

    Institute of Scientific and Technical Information of China (English)

    DENG ShouChun; LIANG NaiGang; LU HaiXing

    2009-01-01

    The potential energy in materials is well approximated by pair functional which is composed of pair potentials and embedding energy. During calculating material potential energy, the orientational com-ponent and the volumetric component are derived respectively from pair potentials and embedding energy. The sum of energy of all these two kinds of components is the material potential. No matter how microstructures change, damage or fracture, at the most level, they are all the changing and breaking atomic bonds. As an abstract of atomic bonds, these components change their stiffness during dam-aging. Material constitutive equations have been formulated by means of assembling all components' response functions. This material model is called the component assembling model. Theoretical analysis and numerical computing indicate that the proposed model has the capacity of reproducing some results satisfactorily, with the advantages of great conceptual simplicity, physical explicitness, and intrinsic induced anisotropy, etc.

  4. How many separable sources? Model selection in independent components analysis.

    Science.gov (United States)

    Woods, Roger P; Hansen, Lars Kai; Strother, Stephen

    2015-01-01

    Unlike mixtures consisting solely of non-Gaussian sources, mixtures including two or more Gaussian components cannot be separated using standard independent components analysis methods that are based on higher order statistics and independent observations. The mixed Independent Components Analysis/Principal Components Analysis (mixed ICA/PCA) model described here accommodates one or more Gaussian components in the independent components analysis model and uses principal components analysis to characterize contributions from this inseparable Gaussian subspace. Information theory can then be used to select from among potential model categories with differing numbers of Gaussian components. Based on simulation studies, the assumptions and approximations underlying the Akaike Information Criterion do not hold in this setting, even with a very large number of observations. Cross-validation is a suitable, though computationally intensive alternative for model selection. Application of the algorithm is illustrated using Fisher's iris data set and Howells' craniometric data set. Mixed ICA/PCA is of potential interest in any field of scientific investigation where the authenticity of blindly separated non-Gaussian sources might otherwise be questionable. Failure of the Akaike Information Criterion in model selection also has relevance in traditional independent components analysis where all sources are assumed non-Gaussian.

  5. Transport of Solar Wind Fluctuations: A Two-Component Model

    Science.gov (United States)

    Oughton, S.; Matthaeus, W. H.; Smith, C. W.; Breech, B.; Isenberg, P. A.

    2011-01-01

    We present a new model for the transport of solar wind fluctuations which treats them as two interacting incompressible components: quasi-two-dimensional turbulence and a wave-like piece. Quantities solved for include the energy, cross helicity, and characteristic transverse length scale of each component, plus the proton temperature. The development of the model is outlined and numerical solutions are compared with spacecraft observations. Compared to previous single-component models, this new model incorporates a more physically realistic treatment of fluctuations induced by pickup ions and yields improved agreement with observed values of the correlation length, while maintaining good observational accord with the energy, cross helicity, and temperature.

  6. Adding heat to the live-high train-low altitude model: a practical insight from professional football

    Science.gov (United States)

    Buchheit, M; Racinais, S; Bilsborough, J; Hocking, J; Mendez-Villanueva, A; Bourdon, P C; Voss, S; Livingston, S; Christian, R; Périard, J; Cordy, J; Coutts, A J

    2013-01-01

    Objectives To examine with a parallel group study design the performance and physiological responses to a 14-day off-season ‘live high-train low in the heat’ training camp in elite football players. Methods Seventeen professional Australian Rules Football players participated in outdoor football-specific skills (32±1°C, 11.5 h) and indoor strength (23±1°C, 9.3 h) sessions and slept (12 nights) and cycled indoors (4.3 h) in either normal air (NORM, n=8) or normobaric hypoxia (14±1 h/day, FiO2 15.2–14.3%, corresponding to a simulated altitude of 2500–3000 m, hypoxic (HYP), n=9). They completed the Yo-Yo Intermittent Recovery level 2 (Yo-YoIR2) in temperate conditions (23±1°C, normal air) precamp (Pre) and postcamp (Post). Plasma volume (PV) and haemoglobin mass (Hbmass) were measured at similar times and 4 weeks postcamp (4WPost). Sweat sodium concentration ((Na+)sweat) was measured Pre and Post during a heat-response test (44°C). Results Both groups showed very large improvements in Yo-YoIR2 at Post (+44%; 90% CL 38, 50), with no between-group differences in the changes (−1%; −9, 9). Postcamp, large changes in PV (+5.6%; −1.8, 5.6) and (Na+)sweat (−29%; −37, −19) were observed in both groups, while Hbmass only moderately increased in HYP (+2.6%; 0.5, 4.5). At 4WPost, there was a likely slightly greater increase in Hbmass (+4.6%; 0.0, 9.3) and PV (+6%; −5, 18, unclear) in HYP than in NORM. Conclusions The combination of heat and hypoxic exposure during sleep/training might offer a promising ‘conditioning cocktail’ in team sports. PMID:24282209

  7. Modeling thermally active building components using space mapping

    DEFF Research Database (Denmark)

    Pedersen, Frank; Weitzmann, Peter; Svendsen, Svend

    2005-01-01

    In order to efficiently implement thermally active building components in new buildings, it is necessary to evaluate the thermal interaction between them and other building components. Applying parameter investigation or numerical optimization methods to a differential-algebraic (DAE) model....... This paper describes the principle of the space mapping technique, and introduces a simple space mapping technique. The technique is applied to a lumped parameter model of a thermo active component, which provides a model of the thermal performance of the component as a function of two design parameters...... of a building provides a systematic way of estimating efficient building designs. However, using detailed numerical calculations of the components in the building is a time consuming process, which may become prohibitive if the DAE model is to be used for parameter variation or optimization. Unfortunately...

  8. Block-Krylov component synthesis method for structural model reduction

    Science.gov (United States)

    Craig, Roy R., Jr.; Hale, Arthur L.

    1988-01-01

    A new analytical method is presented for generating component shape vectors, or Ritz vectors, for use in component synthesis. Based on the concept of a block-Krylov subspace, easily derived recurrence relations generate blocks of Ritz vectors for each component. The subspace spanned by the Ritz vectors is called a block-Krylov subspace. The synthesis uses the new Ritz vectors rather than component normal modes to reduce the order of large, finite-element component models. An advantage of the Ritz vectors is that they involve significantly less computation than component normal modes. Both 'free-interface' and 'fixed-interface' component models are derived. They yield block-Krylov formulations paralleling the concepts of free-interface and fixed-interface component modal synthesis. Additionally, block-Krylov reduced-order component models are shown to have special disturbability/observability properties. Consequently, the method is attractive in active structural control applications, such as large space structures. The new fixed-interface methodology is demonstrated by a numerical example. The accuracy is found to be comparable to that of fixed-interface component modal synthesis.

  9. Investigating the Surface and Subsurface in Karstic Regions – Terrestrial Laser Scanning versus Low-Altitude Airborne Imaging and the Combination with Geophysical Prospecting

    Directory of Open Access Journals (Sweden)

    Nora Tilly

    2017-08-01

    Full Text Available Combining measurements of the surface and subsurface is a promising approach to understand the origin and current changes of karstic forms since subterraneous processes are often the initial driving force. A karst depression in south-west Germany was investigated in a comprehensive campaign with remote sensing and geophysical prospecting. This contribution has two objectives: firstly, comparing terrestrial laser scanning (TLS and low-altitude airborne imaging from an unmanned aerial vehicle (UAV regarding their performance in capturing the surface. Secondly, establishing a suitable way of combining this 3D surface data with data from the subsurface, derived by geophysical prospecting. Both remote sensing approaches performed satisfying and the established digital elevation models (DEMs differ only slightly. These minor discrepancies result essentially from the different viewing geometries and post-processing concepts, for example whether the vegetation was removed or not. Validation analyses against high-accurate DGPS-derived point data sets revealed slightly better results for the DEMTLS with a mean absolute difference of 0.03 m to 0.05 m and a standard deviation of 0.03 m to 0.07 m (DEMUAV: mean absolute difference: 0.11 m to 0.13 m; standard deviation: 0.09 m to 0.11 m. The 3D surface data and 2D image of the vertical cross section through the subsurface along a geophysical profile were combined in block diagrams. The data sets fit very well and give a first impression of the connection between surface and subsurface structures. Since capturing the subsurface with this method is limited to 2D and the data acquisition is quite time consuming, further investigations are necessary for reliable statements about subterraneous structures, how these may induce surface changes, and the origin of this karst depression. Moreover, geophysical prospecting can only produce a suspected image of the subsurface since the apparent resistivity is measured

  10. Optimization of Component Based Software Engineering Model Using Neural Network

    Directory of Open Access Journals (Sweden)

    Gaurav Kumar

    2014-10-01

    Full Text Available The goal of Component Based Software Engineering (CBSE is to deliver high quality, more reliable and more maintainable software systems in a shorter time and within limited budget by reusing and combining existing quality components. A high quality system can be achieved by using quality components, framework and integration process that plays a significant role. So, techniques and methods used for quality assurance and assessment of a component based system is different from those of the traditional software engineering methodology. In this paper, we are presenting a model for optimizing Chidamber and Kemerer (CK metric values of component-based software. A deep analysis of a series of CK metrics of the software components design patterns is done and metric values are drawn from them. By using unsupervised neural network- Self Organizing Map, we have proposed a model that provides an optimized model for Software Component engineering model based on reusability that depends on CK metric values. Average, standard deviated and optimized values for the CK metric are compared and evaluated to show the optimized reusability of component based model.

  11. The elasto-damage theory of the components assembling model

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The potential energy in materials is well approximated by pair functional which is composed of pair potentials and embedding energy. During calculating material potential energy, the orientational component and the volumetric component are derived respectively from pair potentials and embedding energy. The sum of energy of all these two kinds of components is the material potential. No matter how microstructures change, damage or fracture, at the most level, they are all the changing and breaking atomic bonds. As an abstract of atomic bonds, these components change their stiffness during damaging. Material constitutive equations have been formulated by means of assembling all components’ response functions. This material model is called the component assembling model. Theoretical analysis and numerical computing indicate that the proposed model has the capacity of reproducing some results satisfactorily, with the advantages of great conceptual simplicity, physical explicitness, and intrinsic induced anisotropy, etc.

  12. Components in models of learning: Different operationalisations and relations between components

    Directory of Open Access Journals (Sweden)

    Mirkov Snežana

    2013-01-01

    Full Text Available This paper provides the presentation of different operationalisations of components in different models of learning. Special emphasis is on the empirical verifications of relations between components. Starting from the research of congruence between learning motives and strategies, underlying the general model of school learning that comprises different approaches to learning, we have analyzed the empirical verifications of factor structure of instruments containing the scales of motives and learning strategies corresponding to these motives. Considering the problems in the conceptualization of the achievement approach to learning, we have discussed the ways of operational sing the goal orientations and exploring their role in using learning strategies, especially within the model of the regulation of constructive learning processes. This model has served as the basis for researching learning styles that are the combination of a large number of components. Complex relations between the components point to the need for further investigation of the constructs involved in various models. We have discussed the findings and implications of the studies of relations between the components involved in different models, especially between learning motives/goals and learning strategies. We have analyzed the role of regulation in the learning process, whose elaboration, as indicated by empirical findings, can contribute to a more precise operationalisation of certain learning components. [Projekat Ministarstva nauke Republike Srbije, br. 47008: Unapređivanje kvaliteta i dostupnosti obrazovanja u procesima modernizacije Srbije i br. 179034: Od podsticanja inicijative, saradnje i stvaralaštva u obrazovanju do novih uloga i identiteta u društvu

  13. Engine structures analysis software: Component Specific Modeling (COSMO)

    Science.gov (United States)

    McKnight, R. L.; Maffeo, R. J.; Schwartz, S.

    1994-08-01

    A component specific modeling software program has been developed for propulsion systems. This expert program is capable of formulating the component geometry as finite element meshes for structural analysis which, in the future, can be spun off as NURB geometry for manufacturing. COSMO currently has geometry recipes for combustors, turbine blades, vanes, and disks. Component geometry recipes for nozzles, inlets, frames, shafts, and ducts are being added. COSMO uses component recipes that work through neutral files with the Technology Benefit Estimator (T/BEST) program which provides the necessary base parameters and loadings. This report contains the users manual for combustors, turbine blades, vanes, and disks.

  14. FUZZY PRINCIPAL COMPONENT ANALYSIS AND ITS KERNEL BASED MODEL

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Principal Component Analysis (PCA) is one of the most important feature extraction methods, and Kernel Principal Component Analysis (KPCA) is a nonlinear extension of PCA based on kernel methods. In real world, each input data may not be fully assigned to one class and it may partially belong to other classes. Based on the theory of fuzzy sets, this paper presents Fuzzy Principal Component Analysis (FPCA) and its nonlinear extension model, i.e., Kernel-based Fuzzy Principal Component Analysis (KFPCA). The experimental results indicate that the proposed algorithms have good performances.

  15. Component

    Directory of Open Access Journals (Sweden)

    Tibor Tot

    2011-01-01

    Full Text Available A unique case of metaplastic breast carcinoma with an epithelial component showing tumoral necrosis and neuroectodermal stromal component is described. The tumor grew rapidly and measured 9 cm at the time of diagnosis. No lymph node metastases were present. The disease progressed rapidly and the patient died two years after the diagnosis from a hemorrhage caused by brain metastases. The morphology and phenotype of the tumor are described in detail and the differential diagnostic options are discussed.

  16. Optimization Model for Environmental Stress Screening of Electronic Components

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Environmental stress screening (ESS) is a technological process to reduce the costly early field failure ofelectronic components. This paper builds an optimization model for ESS of electronic components to obtain the optimalESS duration. The failure phenomena of ESS are modeled by mix ed distribution, and optimal ESS duration is definedby maximizing life-cycle cost savings under the condition of meeting reliability requirement.

  17. An introduction to modelling of power system components

    CERN Document Server

    Krishna, S

    2014-01-01

    The brief provides a quick introduction to the dynamic modelling of power system components. It gives a rigorous derivation of the model of different components of the power system such as synchronous generator, transformer, transmission line, FACTS, DC transmission system, excitation system and speed governor. Models of load and prime movers are also discussed. The brief can be used as a reference for researchers working in the areas of power system dynamics, stability analysis and design of stability controllers. It can also serve as a text for a short course on power system modelling, or as a supplement for a senior undergraduate/graduate course on power system stability.

  18. 我国低空旅游产品开发研究∗%Research on the Development of Low-altitude Tourism Product in Our Country

    Institute of Scientific and Technical Information of China (English)

    刘又堂

    2015-01-01

    伴随着我国低空空域管制的逐步开放,通用航空产业正以前所未有的速度呈现出井喷式增长态势。将通用航空与旅游开发有机结合起来,实现通用航空产业链的快速延伸与扩张,既是全社会共同关注的热门话题,又是学术界一个崭新的研究领域。在详细介绍低空空域和通用航空产业等相关概念的基础上,深刻阐述了低空旅游的基本含义及消费特点,提出目前条件下我国低空旅游产品开发的主要类型,并对我国低空旅游产品开发的具体策略进行了全面分析和深入探讨。%With the gradual opening of national tourist policies in low altitude,the general avia-tion industry assumes an increasing growth trend at an unprecedented speed.The organic combination of general aviation and tourist development can help the industrial chain of the general aviation to ex-tend and expand rapidly.This is not only a common issue concerned by the whole society,but also a new research field in academia.On the basis of the detailed introduction of low-altitude airspace and general aviation industry,as well as other related concepts,this paper explains what is low-altitude tourism and its consumption patterns.With the main types of low-altitude tourism product in our country being put forward,some specific strategies are discussed in this paper.

  19. Investigation of the Crust of the Pannonian Basin, Hungary Using Low-Altitude CHAMP Horizontal Gradient Magnetic Anomalies

    Science.gov (United States)

    Taylor, Patrick T.; Kis, Karoly I.; Puszta, Sandor; Wittmann, Geza; Kim, Hyung Rae; Toronyi, B.

    2011-01-01

    The Pannonian Basin is a deep intra-continental basin that formed as part of the Alpine orogeny. It is some 600 by 500 km in area and centered on Hungary. This area was chosen since it has one of the thinnest continental crusts in Europe and is the region of complex tectonic structures. In order to study the nature of the crustal basement we used the long-wavelength magnetic anomalies acquired by the CHAMP satellite. The SWARM constellation, scheduled to be launched next year, will have two lower altitude satellites flying abreast, with a separation of between ca. 150 to 200 km. to record the horizontal magnetic gradient. Since the CHAMP satellite has been in orbit for eight years and has obtained an extensive range of data, both vertically and horizontally there is a large enough data base to compute the horizontal magnetic gradients over the Pannonian Basin region using these many CHAMP orbits. We recomputed a satellite magnetic anomaly map, using the spherical-cap method of Haines (1985), the technique of Alsdorf et al. (1994) and from spherical harmonic coefficients of MF6 (Maus et aI., 2008) employing the latest and lowest altitude CHAMP data. We then computed the horizontal magnetic anomaly gradients (Kis and Puszta, 2006) in order to determine how these component data will improve our interpretation and to preview what the SW ARM mission will reveal with reference to the horizontal gradient anomalies. The gradient amplitude of an 1000 km northeast-southwest profile through our horizontal component anomaly map varied from 0 to 0.025 nT/km with twin positive anomalies (0.025 and 0.023 nT/km) separated by a sharp anomaly negative at o nT/km. Horizontal gradient indicate major magnetization boundaries in the crust (Dole and Jordan, 1978 and Cordell and Grauch, 1985). Our gradient anomaly was modeled with a twodimensional body and the anomaly, of some 200 km, correlates with a 200 km area of crustal thinning in the southwestern Pannonian Basin.

  20. Application of variance components estimation to calibrate geoid error models.

    Science.gov (United States)

    Guo, Dong-Mei; Xu, Hou-Ze

    2015-01-01

    The method of using Global Positioning System-leveling data to obtain orthometric heights has been well studied. A simple formulation for the weighted least squares problem has been presented in an earlier work. This formulation allows one directly employing the errors-in-variables models which completely descript the covariance matrices of the observables. However, an important question that what accuracy level can be achieved has not yet to be satisfactorily solved by this traditional formulation. One of the main reasons for this is the incorrectness of the stochastic models in the adjustment, which in turn allows improving the stochastic models of measurement noises. Therefore the issue of determining the stochastic modeling of observables in the combined adjustment with heterogeneous height types will be a main focus point in this paper. Firstly, the well-known method of variance component estimation is employed to calibrate the errors of heterogeneous height data in a combined least square adjustment of ellipsoidal, orthometric and gravimetric geoid. Specifically, the iterative algorithms of minimum norm quadratic unbiased estimation are used to estimate the variance components for each of heterogeneous observations. Secondly, two different statistical models are presented to illustrate the theory. The first method directly uses the errors-in-variables as a priori covariance matrices and the second method analyzes the biases of variance components and then proposes bias-corrected variance component estimators. Several numerical test results show the capability and effectiveness of the variance components estimation procedure in combined adjustment for calibrating geoid error model.

  1. Option valuation with the simplified component GARCH model

    DEFF Research Database (Denmark)

    Dziubinski, Matt P.

    We introduce the Simplified Component GARCH (SC-GARCH) option pricing model, show and discuss sufficient conditions for non-negativity of the conditional variance, apply it to low-frequency and high-frequency financial data, and consider the option valuation, comparing the model performance...

  2. Design and Implementation of Ground Monitoring System in Low - altitude Airship%低空飞艇地面监控系统设计与实现

    Institute of Scientific and Technical Information of China (English)

    茹芬; 侯中峰; 谢利理

    2011-01-01

    The background of this paper is a project of an experimental low - altitude airship. The ground monitoring system in low - altitude airship based on LabWindows/CVI is developed, and some key questions in software design are illustrated in detail, such as low - level communication program design of serial port, joystick programming and airship real -time database design. After a long run, the system software works well, and meets the requirements of the practical needs, as well as being valuable in engineering application.%以某低空实验飞艇项目为背景,基于LabWindows/CVI设计并实现了低空飞艇地面监控系统的上层软件,对底层串口通信程序、飞艇遥控操纵杆程序以及飞艇实时状态数据库连接等几个关键问题进行了详细设计.该地面监控系统经过长期运行表明该监控软件运行稳定,功能完备实用,具有较高的工程应用价值.

  3. Modeling microstructural evolution of multiple texture components during recrystallization

    DEFF Research Database (Denmark)

    Vandermeer, R.A.; Juul Jensen, D.

    1994-01-01

    using stereological point and lineal measurements of microstructural properties in combination with EBSP analysis for orientation determinations. The potential of the models to describe the observed recrystallization behavior of heavily cold-rolled commercial aluminum was demonstrated. A successful MPM......Models were formulated in an effort to characterize recrystallization in materials with multiple texture components. The models are based on a microstructural path methodology (MPM). Experimentally the microstructural evolution of conmmercial aluminum during recrystallization was characterized...

  4. Closure conditions for non-equilibrium multi-component models

    Science.gov (United States)

    Müller, S.; Hantke, M.; Richter, P.

    2016-07-01

    A class of non-equilibrium models for compressible multi-component fluids in multi-dimensions is investigated taking into account viscosity and heat conduction. These models are subject to the choice of interfacial pressures and interfacial velocity as well as relaxation terms for velocity, pressure, temperature and chemical potentials. Sufficient conditions are derived for these quantities that ensure meaningful physical properties such as a non-negative entropy production, thermodynamical stability, Galilean invariance and mathematical properties such as hyperbolicity, subcharacteristic property and existence of an entropy-entropy flux pair. For the relaxation of chemical potentials, a two-component and a three-component models for vapor-water and gas-water-vapor, respectively, are considered.

  5. A probabilistic model for component-based shape synthesis

    KAUST Repository

    Kalogerakis, Evangelos

    2012-07-01

    We present an approach to synthesizing shapes from complex domains, by identifying new plausible combinations of components from existing shapes. Our primary contribution is a new generative model of component-based shape structure. The model represents probabilistic relationships between properties of shape components, and relates them to learned underlying causes of structural variability within the domain. These causes are treated as latent variables, leading to a compact representation that can be effectively learned without supervision from a set of compatibly segmented shapes. We evaluate the model on a number of shape datasets with complex structural variability and demonstrate its application to amplification of shape databases and to interactive shape synthesis. © 2012 ACM 0730-0301/2012/08-ART55.

  6. Container-component model and XML in ALMA ACS

    Science.gov (United States)

    Sommer, Heiko; Chiozzi, Gianluca; Zagar, Klemen; Voelter, Markus

    2004-09-01

    ALMA software, from high-level data flow applications down to instrument control, is built using the ACS framework. To meet the challenges of developing distributed software in distributed teams, ACS offers a container/component model that integrates the use of XML transfer objects. ACS containers are built on top of CORBA and are available for C++, Java, and Python, so that ALMA software can be written as components in any of these languages. The containers perform technical aspects of the software system, while components can focus on the implementation of functional requirements. Like Web services, components can use XML to exchange structured data by value. For Java components, the container seamlessly integrates the use of XML binding classes, which are Java classes that encapsulate access to XML data through type-safe methods. Binding classes are generated from XML schemas, allowing the Java compiler to enforce compliance of application code with the XML schemas. This presentation will explain the capabilities of the ACS container/component model, and how it relates to other middleware technologies that are popular in industry.

  7. A viscoplastic model for the active component in cardiac muscle.

    Science.gov (United States)

    Rubin, M B

    2016-08-01

    The HMK model (Hunter et al. in Prog Biophys Mol Biol 69:289-331, 1998) proposes mechanobiological equations for the influence of intracellular calcium concentration [Formula: see text] on the evolution of bound calcium concentration [Formula: see text] and the tropomyosin kinetics parameter z, which model processes in the active component of the tension in cardiac muscle. The inelastic response due to actin-myosin crossbridge kinetics is modeled in the HMK model with a function Q that depends on the history of the rate of total stretch of the muscle fiber. Here, an alternative model is proposed which models the active component of the muscle fiber as a viscoplastic material. In particular, an evolution equation is proposed for the elastic stretch [Formula: see text] in the active component. Specific forms of the constitutive equations are proposed and used to match experimental data. The proposed viscoplastic formulation allows for separate modeling of three processes: the high rate deactivation of crossbridges causing rapid reduction in active tension; the high but lower rate reactivation of crossbridges causing recovery of active tension; and the low rate relaxation effects characterizing the Hill model of muscles.

  8. Towards a Component Based Model for Database Systems

    Directory of Open Access Journals (Sweden)

    Octavian Paul ROTARU

    2004-02-01

    Full Text Available Due to their effectiveness in the design and development of software applications and due to their recognized advantages in terms of reusability, Component-Based Software Engineering (CBSE concepts have been arousing a great deal of interest in recent years. This paper presents and extends a component-based approach to object-oriented database systems (OODB introduced by us in [1] and [2]. Components are proposed as a new abstraction level for database system, logical partitions of the schema. In this context, the scope is introduced as an escalated property for transactions. Components are studied from the integrity, consistency, and concurrency control perspective. The main benefits of our proposed component model for OODB are the reusability of the database design, including the access statistics required for a proper query optimization, and a smooth information exchange. The integration of crosscutting concerns into the component database model using aspect-oriented techniques is also discussed. One of the main goals is to define a method for the assessment of component composition capabilities. These capabilities are restricted by the component’s interface and measured in terms of adaptability, degree of compose-ability and acceptability level. The above-mentioned metrics are extended from database components to generic software components. This paper extends and consolidates into one common view the ideas previously presented by us in [1, 2, 3].[1] Octavian Paul Rotaru, Marian Dobre, Component Aspects in Object Oriented Databases, Proceedings of the International Conference on Software Engineering Research and Practice (SERP’04, Volume II, ISBN 1-932415-29-7, pages 719-725, Las Vegas, NV, USA, June 2004.[2] Octavian Paul Rotaru, Marian Dobre, Mircea Petrescu, Integrity and Consistency Aspects in Component-Oriented Databases, Proceedings of the International Symposium on Innovation in Information and Communication Technology (ISIICT

  9. Mott transitions in three-component Falicov-Kimball model

    Science.gov (United States)

    Nguyen, Duong-Bo; Tran, Minh-Tien

    2013-01-01

    Metal-insulator transitions are studied within a three-component Falicov-Kimball model, which mimics a mixture of one-component and two-component fermionic particles with local repulsive interactions in optical lattices. Within the model, the two-component fermionic particles are able to hop in the lattice, while the one-component fermionic particles are localized. The model is studied by using the dynamical mean-field theory with exact diagonalization. Its homogeneous solutions establish Mott transitions for both commensurate and incommensurate fillings between one-third and two-thirds. At commensurate one-third and two-thirds fillings, the Mott transition occurs for any density of hopping particles, while at incommensurate fillings, the Mott transition can occur only for density one-half of hopping particles. At half-filling, depending on the repulsive interactions, the reentrant effect of the Mott insulator is observed. As increasing local interaction of hopping particles, the first insulator-metal transition is continuous, whereas the second metal-insulator transition is discontinuous. The second metal-insulator transition crosses a finite region where both metallic and insulating phase coexist. At third-filling, the Mott transition is established only for strong repulsive interactions. A phase separation occurs together with the phase transition.

  10. Efficient speaker verification using Gaussian mixture model component clustering.

    Energy Technology Data Exchange (ETDEWEB)

    De Leon, Phillip L. (New Mexico State University, Las Cruces, NM); McClanahan, Richard D.

    2012-04-01

    In speaker verification (SV) systems that employ a support vector machine (SVM) classifier to make decisions on a supervector derived from Gaussian mixture model (GMM) component mean vectors, a significant portion of the computational load is involved in the calculation of the a posteriori probability of the feature vectors of the speaker under test with respect to the individual component densities of the universal background model (UBM). Further, the calculation of the sufficient statistics for the weight, mean, and covariance parameters derived from these same feature vectors also contribute a substantial amount of processing load to the SV system. In this paper, we propose a method that utilizes clusters of GMM-UBM mixture component densities in order to reduce the computational load required. In the adaptation step we score the feature vectors against the clusters and calculate the a posteriori probabilities and update the statistics exclusively for mixture components belonging to appropriate clusters. Each cluster is a grouping of multivariate normal distributions and is modeled by a single multivariate distribution. As such, the set of multivariate normal distributions representing the different clusters also form a GMM. This GMM is referred to as a hash GMM which can be considered to a lower resolution representation of the GMM-UBM. The mapping that associates the components of the hash GMM with components of the original GMM-UBM is referred to as a shortlist. This research investigates various methods of clustering the components of the GMM-UBM and forming hash GMMs. Of five different methods that are presented one method, Gaussian mixture reduction as proposed by Runnall's, easily outperformed the other methods. This method of Gaussian reduction iteratively reduces the size of a GMM by successively merging pairs of component densities. Pairs are selected for merger by using a Kullback-Leibler based metric. Using Runnal's method of reduction, we

  11. Modeling fabrication of nuclear components: An integrative approach

    Energy Technology Data Exchange (ETDEWEB)

    Hench, K.W.

    1996-08-01

    Reduction of the nuclear weapons stockpile and the general downsizing of the nuclear weapons complex has presented challenges for Los Alamos. One is to design an optimized fabrication facility to manufacture nuclear weapon primary components in an environment of intense regulation and shrinking budgets. This dissertation presents an integrative two-stage approach to modeling the casting operation for fabrication of nuclear weapon primary components. The first stage optimizes personnel radiation exposure for the casting operation layout by modeling the operation as a facility layout problem formulated as a quadratic assignment problem. The solution procedure uses an evolutionary heuristic technique. The best solutions to the layout problem are used as input to the second stage - a simulation model that assesses the impact of competing layouts on operational performance. The focus of the simulation model is to determine the layout that minimizes personnel radiation exposures and nuclear material movement, and maximizes the utilization of capacity for finished units.

  12. Principal Component-Discrimination Model and Its Application

    Institute of Scientific and Technical Information of China (English)

    韩天锡; 魏雪丽; 蒋淳; 张玉琍

    2004-01-01

    Having researched for many years, seismologists in China presented about 80 earthquake prediction factors which reflected omen information of earthquake. How to concentrate the information that the 80 earthquake prediction factors have and how to choose the main factors to predict earthquakes precisely have become one of the topics in seismology. The model of principal component-discrimination consists of principal component analysis, correlation analysis, weighted method of principal factor coefficients and Mahalanobis distance discrimination analysis. This model combines the method of maximization earthquake prediction factor information with the weighted method of principal factor coefficients and correlation analysis to choose earthquake prediction variables, applying Mahalanobis distance discrimination to establishing earthquake prediction discrimination model. This model was applied to analyzing the earthquake data of Northern China area and obtained good prediction results.

  13. Reo: A Channel-based Coordination Model for Component Composition

    NARCIS (Netherlands)

    Arbab, F.

    2004-01-01

    In this paper, we present Reo, which forms a paradigm for composition of software components based on the notion of mobile channels. Reo is a channel-based exogenous coordination model in which complex coordinators, called connectors, are compositionally built out of simpler ones. The simplest conne

  14. A channel-based coordination model for component composition

    NARCIS (Netherlands)

    Arbab, F.

    2002-01-01

    In this paper, we present $P epsilon omega$, a paradigm for composition of software components based on the notion of mobile channels. $P repsilon omega$ is a channel-based exogenous coordination model wherein complex coordinators, called {em connectors are compositionally built out of simpler ones.

  15. Sparse Principal Component Analysis in Medical Shape Modeling

    DEFF Research Database (Denmark)

    Sjöstrand, Karl; Stegmann, Mikkel Bille; Larsen, Rasmus

    2006-01-01

    Principal component analysis (PCA) is a widely used tool in medical image analysis for data reduction, model building, and data understanding and exploration. While PCA is a holistic approach where each new variable is a linear combination of all original variables, sparse PCA (SPCA) aims...

  16. Incremental principal component pursuit for video background modeling

    Energy Technology Data Exchange (ETDEWEB)

    Rodriquez-Valderrama, Paul A.; Wohlberg, Brendt

    2017-03-14

    An incremental Principal Component Pursuit (PCP) algorithm for video background modeling that is able to process one frame at a time while adapting to changes in background, with a computational complexity that allows for real-time processing, having a low memory footprint and is robust to translational and rotational jitter.

  17. Robustness of Component Models in Energy System Simulators

    DEFF Research Database (Denmark)

    Elmegaard, Brian

    2003-01-01

    During the development of the component-based energy system simulator DNA (Dynamic Network Analysis), several obstacles to easy use of the program have been observed. Some of these have to do with the nature of the program being based on a modelling language, not a graphical user interface (GUI...

  18. Functional models of power electronic components for system studies

    Science.gov (United States)

    Tam, Kwa-Sur; Yang, Lifeng; Dravid, Narayan

    1991-01-01

    A novel approach to model power electronic circuits has been developed to facilitate simulation studies of system-level issues. The underlying concept for this approach is to develop an equivalent circuit, the functional model, that performs the same functions as the actual circuit but whose operation can be simulated by using larger time step size and the reduction in model complexity, the computation time required by a functional model is significantly shorter than that required by alternative approaches. The authors present this novel modeling approach and discuss the functional models of two major power electronic components, the DC/DC converter unit and the load converter, that are being considered by NASA for use in the Space Station Freedom electric power system. The validity of these models is established by comparing the simulation results with available experimental data and other simulation results obtained by using a more established modeling approach. The usefulness of this approach is demonstrated by incorporating these models into a power system model and simulating the system responses and interactions between components under various conditions.

  19. 有限干预下的 UAV 低空突防航迹规划%Human intervention flight path planning for UAV low-altitude penetration

    Institute of Scientific and Technical Information of China (English)

    任鹏; 高晓光

    2014-01-01

    低空突防航迹规划是实现有人机和无人机(unmanned aerial vehicle,UAV)编队协同作战的关键技术,针对目前智能算法在求解低空突防航迹规划问题中存在的不足,充分发挥人脑这个超级智能系统来引导飞行航迹求解过程,将基于角度量编码的小生境伪并行自适应遗传算法(niche adaptive pseudo parallel genetic algo-rithm,NAPPGA)和人有限干预情况下的智能决策结合起来,提出 UAV 低空突防航迹规划技术。通过大量仿真计算,结果表明,应用该技术预规划和重规划的三维航迹能够有效实现威胁回避、地形回避和地形跟随,满足UAV 低空突防要求,具有一定的实用性。%The flight path planning for unmanned aerial vehicle (UAV)low-altitude penetration is a key technology for achieving manned and unmanned aerial vehicles cooperative combat.The technique of human in-tervention flight path planning for UAV low-altitude penetration against several limitations of the existing intel-ligent algorithms is proposed.It makes full use of the human brain to guide the solution procedures of the flight path planning,combining the niche adaptive pseudo parallel genetic algorithm (NAPPGA)based on angle codes and the intelligent decision with human intervention.A lot of simulation studies show that the solving off-line and on-line three-dimensional flight paths by this technique can meet the requirements for UAV low-altitude penetration to realize efficient implementation of threat avoidance,terrain avoidance and terrain following.This method has a certain practicality.

  20. 基于微物理特性的三维低空风切变雷达回波仿真%Microphysics-based radar signal simulation for the three-dimensional low altitude wind shear

    Institute of Scientific and Technical Information of China (English)

    韩雁飞; 刘夏; 李海; 吴仁彪

    2016-01-01

    As in landing or takeoff,approach or takeoff,low altitude wind shear is one of the most danger-ous weather phenomenon to the aviation safety.Due to the characteristics of suddenness,short duration,heavy intensity and high hazard,it is difficult to obtain the real radar data of the wind shear.Based on the terminal ar-ea simulation system (TASS)model and combined with microphysical property of wind shear,a 3D wind field model is proposed by using the computational fluid dynamics method.After the preprocessing of the original non uniform wind field data,the scanning parameters are set up in accordance with the real airborne weather radar,the sprinkle point method is used to implement low altitude wind shear high-fidelity 3D signal simulation.Results of simu-lation prove that the proposed method can provide effective and reliable simulation data,which can veritably reflect the meteorological characteristics of the wind shear echo signals,and the design of the simulation process is reasonable.%低空风切变是一种危险性非常高的恶劣天气现象,对民航飞机起飞和着陆阶段的航行安全威胁最大。由于其具有发生突然、持续时间较短、影响强度大和危险性高等特点,使得真实的雷达回波数据难以轻易获取。在分析风切变目标微物理特性的基础上,利用计算流体力学的仿真方法建立三维风场模型,在对非均匀的原始风场数据进行预处理之后,依据民航装机使用的机载气象雷达设备设置扫描参数,利用逐脉冲撒点仿真法实现高保真的三维低空风切变雷达回波仿真。仿真结果表明,雷达回波数据可真实地反映出风切变信号的气象特征,仿真过程设计合理,仿真数据有效可靠。

  1. Dynamic blade row compression component model for stability studies

    Science.gov (United States)

    Tesch, W. A.; Steenken, W. G.

    1976-01-01

    This paper describes a generalized dynamic model which has been developed for use in compression component aerodynamic stability studies. The model is a one-dimensional, pitch-line, blade row, lumped volume system. Arbitrary placement of blade free volumes upstream, within, and downstream of the compression component as well as the removal of bleed flow from the exit of any rotor or stator are model options. The model has been applied to a two-stage fan and an eight-stage compressor. The clean inlet pressure ratio/flow maps and the surge line have been reproduced, thereby validating the capability of the dynamic model to reproduce the steady-flow characteristics of the compression component. A method for determining the onset of an aerodynamic instability which is associated with surge is described. Sinusoidally time-varying inlet and exit boundary conditions have been applied to the eight stage compressor as examples of the manner in which this model may be used for stability studies.

  2. Stochastic modeling of deterioration in nuclear power plant components

    Science.gov (United States)

    Yuan, Xianxun

    2007-12-01

    The risk-based life-cycle management of engineering systems in a nuclear power plant is intended to ensure safe and economically efficient operation of energy generation infrastructure over its entire service life. An important element of life-cycle management is to understand, model and forecast the effect of various degradation mechanisms affecting the performance of engineering systems, structures and components. The modeling of degradation in nuclear plant components is confounded by large sampling and temporal uncertainties. The reason is that nuclear systems are not readily accessible for inspections due to high level of radiation and large costs associated with remote data collection methods. The models of degradation used by industry are largely derived from ordinary linear regression methods. The main objective of this thesis is to develop more advanced techniques based on stochastic process theory to model deterioration in engineering components with the purpose of providing more scientific basis to life-cycle management of aging nuclear power plants. This thesis proposes a stochastic gamma process (GP) model for deterioration and develops a suite of statistical techniques for calibrating the model parameters. The gamma process is a versatile and mathematically tractable stochastic model for a wide variety of degradation phenomena, and another desirable property is its nonnegative, monotonically increasing sample paths. In the thesis, the GP model is extended by including additional covariates and also modeling for random effects. The optimization of age-based replacement and condition-based maintenance strategies is also presented. The thesis also investigates improved regression techniques for modeling deterioration. A linear mixed-effects (LME) regression model is presented to resolve an inconsistency of the traditional regression models. The proposed LME model assumes that the randomness in deterioration is decomposed into two parts: the unobserved

  3. Modeling cellular networks in fading environments with dominant specular components

    KAUST Repository

    AlAmmouri, Ahmad

    2016-07-26

    Stochastic geometry (SG) has been widely accepted as a fundamental tool for modeling and analyzing cellular networks. However, the fading models used with SG analysis are mainly confined to the simplistic Rayleigh fading, which is extended to the Nakagami-m fading in some special cases. However, neither the Rayleigh nor the Nakagami-m accounts for dominant specular components (DSCs) which may appear in realistic fading channels. In this paper, we present a tractable model for cellular networks with generalized two-ray (GTR) fading channel. The GTR fading explicitly accounts for two DSCs in addition to the diffuse components and offers high flexibility to capture diverse fading channels that appear in realistic outdoor/indoor wireless communication scenarios. It also encompasses the famous Rayleigh and Rician fading as special cases. To this end, the prominent effect of DSCs is highlighted in terms of average spectral efficiency. © 2016 IEEE.

  4. Are small-scale field-aligned currents and magneto sheath-like particle precipitation signatures of the same low-altitude cusp?

    DEFF Research Database (Denmark)

    Watermann, J.; Stauning, P.; Luhr, H.

    2009-01-01

    We examined some 75 observations from the low-altitude Earth orbiting DMSP, Orsted and CHAMP satellites which were taken in the region of the nominal cusp. Our objective was to determine whether the actually observed cusp locations as inferred from magnetosheath-like particle precipitation...... of the satellites were converted into AACGM coordinates, and the geomagnetic latitude of the cusp boundaries (as indicated by precipitating particles and small-scale field-aligned currents) set in relation to the IMF-B-z dependent latitude of the equatorward boundary of the statistical cusp. We find...... that intense small-scale field-aligned currents are generated in the cusp but also in the transition zone between the low-latitude boundary layer (LLBL) and the cusp, probably within both regimes, the cusp and the open LLBL. The small-scale field-aligned currents are possibly a consequence of turbulence and...

  5. Experiment teaching of unmanned airship low-altitude photogrammetry technology%无人飞艇低空摄影测量技术实验教学研究

    Institute of Scientific and Technical Information of China (English)

    王冬; 刘凤英; 王志勇

    2013-01-01

    In the paper, some analysis on the photogrammetry experiment teaching of the current domestic universities and the employment needs of some mapping production units were given. In order to respond the policies of National Administration of Surveying, Mapping and Geoinformation for promoting the unmanned aerial vehicle system, and with the situation of our school's photogrammetry teaching and the laboratory's equipments such as the unmanned airship low-altitude photogrammetry system, some teaching reforms for photogrammetry experiment and the characteristic teaching projects of domestic universities based on the unmanned airship low-altitude photogrammetry system were done. By designing the reasonable experimental content and methods, the students could be interested in profession and exercise their practical ability. Then the teaching quality of photogrammetry could be improved .%本文分析了目前国内高校摄影测量实验教学情况和一些测绘生产单位的用人需求,积极响应国家测绘地理信息局对无人飞行器航测系统的推广政策,结合我校无人飞艇低空摄影测量系统等实验室现有的仪器设备和摄影测量教学现状,积极进行摄影测量实验教学改革,以无人飞艇航测系统为基础建立国内高校摄影测量特色实验教学项目,通过设计合理的实验教学内容和方法,培养学生对专业的兴趣,锻练学生的实践动手能力,提升摄影测量学教学质量.

  6. Low Altitude Target Detection Technique Based on Signal Detection of Radar Altimeter%基于雷达高度表信号的低空目标检测技术

    Institute of Scientific and Technical Information of China (English)

    韩兴斌; 颜坤玉; 冯富强

    2015-01-01

    针对低空目标突袭的威胁,根据低空目标普遍携带雷达高度表的特征,提出了基于雷达高度表信号探测的低空目标检测技术。针对海面飞行环境,根据双基地雷达的原理,对海面雷达散射信号进行了理论计算,从功率角度对低空目标检测可行性进行了分析,并给出了将侦察系统升空探测低空目标所携雷达高度表信号的方法,达到了对低空突防目标预警探测的要求。%A Low altitude target detection technique based on signal detection of radar altimeter is proposed to resolve the problem of low altitude target attack, as low altitude targets widely take radar altimeter. The method of heightening reconnaissance system to detect radar altimeter signal of low altitude target is proposed in environment of sea surface, which can satisfy the de-sire of warning detect of low altitude targets.

  7. Four-component united-atom model of bitumen

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt; Lemarchand, Claire; Nielsen, Erik

    2013-01-01

    We propose a four-component united-atom molecular model of bitumen. The model includes realistic chemical constituents and introduces a coarse graining level that suppresses the highest frequency modes. Molecular dynamics simulations of the model are carried out using graphic-processor-units based...... software in time spans in order of microseconds, which enables the study of slow relaxation processes characterizing bitumen. This paper also presents results of the model dynamics as expressed through the mean-square displacement, the stress autocorrelation function, and rotational relaxation...... the stress autocorrelation function, the shear viscosity and shear modulus are evaluated, showing a viscous response at frequencies below 100 MHz. The model predictions of viscosity and diffusivities are compared to experimental data, giving reasonable agreement. The model shows that the asphaltene, resin...

  8. Formal Model-Driven Engineering: Generating Data and Behavioural Components

    Directory of Open Access Journals (Sweden)

    Chen-Wei Wang

    2012-12-01

    Full Text Available Model-driven engineering is the automatic production of software artefacts from abstract models of structure and functionality. By targeting a specific class of system, it is possible to automate aspects of the development process, using model transformations and code generators that encode domain knowledge and implementation strategies. Using this approach, questions of correctness for a complex, software system may be answered through analysis of abstract models of lower complexity, under the assumption that the transformations and generators employed are themselves correct. This paper shows how formal techniques can be used to establish the correctness of model transformations used in the generation of software components from precise object models. The source language is based upon existing, formal techniques; the target language is the widely-used SQL notation for database programming. Correctness is established by giving comparable, relational semantics to both languages, and checking that the transformations are semantics-preserving.

  9. Longitudinal functional principal component modelling via Stochastic Approximation Monte Carlo

    KAUST Repository

    Martinez, Josue G.

    2010-06-01

    The authors consider the analysis of hierarchical longitudinal functional data based upon a functional principal components approach. In contrast to standard frequentist approaches to selecting the number of principal components, the authors do model averaging using a Bayesian formulation. A relatively straightforward reversible jump Markov Chain Monte Carlo formulation has poor mixing properties and in simulated data often becomes trapped at the wrong number of principal components. In order to overcome this, the authors show how to apply Stochastic Approximation Monte Carlo (SAMC) to this problem, a method that has the potential to explore the entire space and does not become trapped in local extrema. The combination of reversible jump methods and SAMC in hierarchical longitudinal functional data is simplified by a polar coordinate representation of the principal components. The approach is easy to implement and does well in simulated data in determining the distribution of the number of principal components, and in terms of its frequentist estimation properties. Empirical applications are also presented.

  10. A minimal model for two-component dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Esch, Sonja; Klasen, Michael; Yaguna, Carlos E. [Institut fuer theoretische Physik, Universitaet Muenster, Wilhelm-Klemm-Strasse 9,D-48149 Muenster (Germany)

    2015-07-01

    We propose and study a new minimal model for two-component dark matter. The model contains only three additional fields, one fermion and two scalars, all singlets under the Standard Model gauge group. Two of these fields, one fermion and one scalar, are odd under a Z{sub 2} symmetry that renders them simultaneously stable. Thus, both particles contribute to the observed dark matter density. This model resembles the union of the singlet scalar and the singlet fermionic models but it contains some new features of its own. We analyze in some detail its dark matter phenomenology. Regarding the relic density, the main novelty is the possible annihilation of one dark matter particle into the other, which can affect the predicted relic density in a significant way. Regarding dark matter detection, we identify a new contribution that can lead either to an enhancement or to a suppression of the spin-independent cross section for the scalar dark matter particle. Finally, we define a set of five benchmarks models compatible with all present bounds and examine their direct detection prospects at planned experiments. A generic feature of this model is that both particles give rise to observable signals in 1-ton direct detection experiments. In fact, such experiments will be able to probe even a subdominant dark matter component at the percent level.

  11. A minimal model for two-component dark matter

    Science.gov (United States)

    Esch, Sonja; Klasen, Michael; Yaguna, Carlos E.

    2014-09-01

    We propose and study a new minimal model for two-component dark matter. The model contains only three additional fields, one fermion and two scalars, all singlets under the Standard Model gauge group. Two of these fields, one fermion and one scalar, are odd under a Z 2 symmetry that renders them simultaneously stable. Thus, both particles contribute to the observed dark matter density. This model resembles the union of the singlet scalar and the singlet fermionic models but it contains some new features of its own. We analyze in some detail its dark matter phenomenology. Regarding the relic density, the main novelty is the possible annihilation of one dark matter particle into the other, which can affect the predicted relic density in a significant way. Regarding dark matter detection, we identify a new contribution that can lead either to an enhancement or to a suppression of the spin-independent cross section for the scalar dark matter particle. Finally, we define a set of five benchmarks models compatible with all present bounds and examine their direct detection prospects at planned experiments. A generic feature of this model is that both particles give rise to observable signals in 1-ton direct detection experiments. In fact, such experiments will be able to probe even a subdominant dark matter component at the percent level.

  12. Mathematical and computer modeling of component surface shaping

    Science.gov (United States)

    Lyashkov, A.

    2016-04-01

    The process of shaping technical surfaces is an interaction of a tool (a shape element) and a component (a formable element or a workpiece) in their relative movements. It was established that the main objects of formation are: 1) a discriminant of a surfaces family, formed by the movement of the shape element relatively the workpiece; 2) an enveloping model of the real component surface obtained after machining, including transition curves and undercut lines; 3) The model of cut-off layers obtained in the process of shaping. When modeling shaping objects there are a lot of insufficiently solved or unsolved issues that make up a single scientific problem - a problem of qualitative shaping of the surface of the tool and then the component surface produced by this tool. The improvement of known metal-cutting tools, intensive development of systems of their computer-aided design requires further improvement of the methods of shaping the mating surfaces. In this regard, an important role is played by the study of the processes of shaping of technical surfaces with the use of the positive aspects of analytical and numerical mathematical methods and techniques associated with the use of mathematical and computer modeling. The author of the paper has posed and has solved the problem of development of mathematical, geometric and algorithmic support of computer-aided design of cutting tools based on computer simulation of the shaping process of surfaces.

  13. Principal component and factor analytic models in international sire evaluation

    Directory of Open Access Journals (Sweden)

    Jakobsen Jette

    2011-09-01

    Full Text Available Abstract Background Interbull is a non-profit organization that provides internationally comparable breeding values for globalized dairy cattle breeding programmes. Due to different trait definitions and models for genetic evaluation between countries, each biological trait is treated as a different trait in each of the participating countries. This yields a genetic covariance matrix of dimension equal to the number of countries which typically involves high genetic correlations between countries. This gives rise to several problems such as over-parameterized models and increased sampling variances, if genetic (covariance matrices are considered to be unstructured. Methods Principal component (PC and factor analytic (FA models allow highly parsimonious representations of the (covariance matrix compared to the standard multi-trait model and have, therefore, attracted considerable interest for their potential to ease the burden of the estimation process for multiple-trait across country evaluation (MACE. This study evaluated the utility of PC and FA models to estimate variance components and to predict breeding values for MACE for protein yield. This was tested using a dataset comprising Holstein bull evaluations obtained in 2007 from 25 countries. Results In total, 19 principal components or nine factors were needed to explain the genetic variation in the test dataset. Estimates of the genetic parameters under the optimal fit were almost identical for the two approaches. Furthermore, the results were in a good agreement with those obtained from the full rank model and with those provided by Interbull. The estimation time was shortest for models fitting the optimal number of parameters and prolonged when under- or over-parameterized models were applied. Correlations between estimated breeding values (EBV from the PC19 and PC25 were unity. With few exceptions, correlations between EBV obtained using FA and PC approaches under the optimal fit were

  14. Reducing component estimation for varying coefficient models with longitudinal data

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Varying-coefficient models with longitudinal observations are very useful in epidemiology and some other practical fields.In this paper,a reducing component procedure is proposed for es- timating the unknown functions and their derivatives in very general models,in which the unknown coefficient functions admit different or the same degrees of smoothness and the covariates can be time- dependent.The asymptotic properties of the estimators,such as consistency,rate of convergence and asymptotic distribution,are derived.The asymptotic results show that the asymptotic variance of the reducing component estimators is smaller than that of the existing estimators when the coefficient functions admit different degrees of smoothness.Finite sample properties of our procedures are studied through Monte Carlo simulations.

  15. Virtual Models Linked with Physical Components in Construction

    DEFF Research Database (Denmark)

    Sørensen, Kristian Birch

    The use of virtual models supports a fundamental change in the working practice of the construction industry. It changes the primary information carrier (drawings) from simple manually created depictions of the building under construction to visually realistic digital representations that also...... components in the construction process and thereby improving the information handling. The present PhD project has examined the potential of establishing such a digital link between virtual models and physical components in construction. This is done by integrating knowledge of civil engineering, software...... engineering and business development in an iterative and user needs centred system development process. The analysis of future business perspectives presents an extensive number of new working processes that can assist in solving major challenges in the construction industry. Three of the most promising...

  16. Orbital component extraction by time-variant sinusoidal modeling.

    Science.gov (United States)

    Sinnesael, Matthias; Zivanovic, Miroslav; De Vleeschouwer, David; Claeys, Philippe; Schoukens, Johan

    2016-04-01

    Accurately deciphering periodic variations in paleoclimate proxy signals is essential for cyclostratigraphy. Classical spectral analysis often relies on methods based on the (Fast) Fourier Transformation. This technique has no unique solution separating variations in amplitude and frequency. This characteristic makes it difficult to correctly interpret a proxy's power spectrum or to accurately evaluate simultaneous changes in amplitude and frequency in evolutionary analyses. Here, we circumvent this drawback by using a polynomial approach to estimate instantaneous amplitude and frequency in orbital components. This approach has been proven useful to characterize audio signals (music and speech), which are non-stationary in nature (Zivanovic and Schoukens, 2010, 2012). Paleoclimate proxy signals and audio signals have in nature similar dynamics; the only difference is the frequency relationship between the different components. A harmonic frequency relationship exists in audio signals, whereas this relation is non-harmonic in paleoclimate signals. However, the latter difference is irrelevant for the problem at hand. Using a sliding window approach, the model captures time variations of an orbital component by modulating a stationary sinusoid centered at its mean frequency, with a single polynomial. Hence, the parameters that determine the model are the mean frequency of the orbital component and the polynomial coefficients. The first parameter depends on geologic interpretation, whereas the latter are estimated by means of linear least-squares. As an output, the model provides the orbital component waveform, either in the depth or time domain. Furthermore, it allows for a unique decomposition of the signal into its instantaneous amplitude and frequency. Frequency modulation patterns can be used to reconstruct changes in accumulation rate, whereas amplitude modulation can be used to reconstruct e.g. eccentricity-modulated precession. The time-variant sinusoidal model

  17. A polaritonic two-component Bose-Hubbard model

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, M J; Brandao, F G S L; Plenio, M B [Institute for Mathematical Sciences, Imperial College London, 53 Exhibition Road, SW7 2PE (United Kingdom)], E-mail: m.hartmann@imperial.ac.uk

    2008-03-15

    We demonstrate that polaritons in an array of interacting micro-cavities with strong atom-photon coupling can form a two-component Bose-Hubbard model in which both polariton species are protected against spontaneous emission as their atomic part is stored in two ground states of the atoms. The parameters of the effective model can be tuned via the driving strength of external lasers and include attractive and repulsive polariton interactions. We also describe a method to measure the number statistics in one cavity for each polariton species independently.

  18. Very low frequency radio events with a reduced intensity observed by the low-altitude DEMETER spacecraft

    Science.gov (United States)

    Záhlava, J.; Němec, F.; Santolík, O.; Kolmašová, I.; Parrot, M.; Rodger, C. J.

    2015-11-01

    We present results of a systematic study of unusual very low frequency (VLF) radio events with a reduced intensity observed in the frequency-time spectrograms measured by the low-orbiting Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) spacecraft. They occur exclusively on the nightside. During these events, the intensity of fractional hop whistlers at specific frequencies is significantly reduced. These frequencies are usually above about 3.4 kHz (second Earth-ionosphere waveguide cutoff frequency), but about 20% of events extend down to about 1.7 kHz (first Earth-ionosphere waveguide cutoff frequency). The frequencies of a reduced intensity vary smoothly with time. We have inspected 6.5 years of DEMETER data, and we identified in total 1601 such events. We present a simple model of the event formation based on the wave propagation in the Earth-ionosphere waveguide. We apply the model to two selected events, and we demonstrate that the model is able to reproduce both the minimum frequencies of the events and their approximate frequency-time shapes. The overall geographic distribution of the events is shifted by about 3000 km westward and slightly southward with respect to the areas with high long-term average lightning activity. We demonstrate that this shift is related to the specific DEMETER orbit, and we suggest its qualitative explanation by the east-west asymmetry of the wave propagation in the Earth-ionosphere waveguide.

  19. Modelling raster-based monthly water balance components for Europe

    Energy Technology Data Exchange (ETDEWEB)

    Ulmen, C.

    2000-11-01

    The terrestrial runoff component is a comparatively small but sensitive and thus significant quantity in the global energy and water cycle at the interface between landmass and atmosphere. As opposed to soil moisture and evapotranspiration which critically determine water vapour fluxes and thus water and energy transport, it can be measured as an integrated quantity over a large area, i.e. the river basin. This peculiarity makes terrestrial runoff ideally suited for the calibration, verification and validation of general circulation models (GCMs). Gauging stations are not homogeneously distributed in space. Moreover, time series are not necessarily continuously measured nor do they in general have overlapping time periods. To overcome this problems with regard to regular grid spacing used in GCMs, different methods can be applied to transform irregular data to regular so called gridded runoff fields. The present work aims to directly compute the gridded components of the monthly water balance (including gridded runoff fields) for Europe by application of the well-established raster-based macro-scale water balance model WABIMON used at the Federal Institute of Hydrology, Germany. Model calibration and validation is performed by separated examination of 29 representative European catchments. Results indicate a general applicability of the model delivering reliable overall patterns and integrated quantities on a monthly basis. For time steps less then too weeks further research and structural improvements of the model are suggested. (orig.)

  20. Modeling of Shock Propagation and Attenuation in Viscoelastic Components

    Directory of Open Access Journals (Sweden)

    R. Rusovici

    2001-01-01

    Full Text Available Protection from the potentially damaging effects of shock loading is a common design requirement for diverse mechanical structures ranging from shock accelerometers to spacecraft. High damping viscoelastic materials are employed in the design of geometrically complex, impact-absorbent components. Since shock transients are characterized by a broad frequency spectrum, it is imperative to properly model frequency dependence of material behavior over a wide frequency range. The Anelastic Displacement Fields (ADF method is employed herein to model frequency-dependence within a time-domain finite element framework. Axisymmetric, ADF finite elements are developed and then used to model shock propagation and absorption through viscoelastic structures. The model predictions are verified against longitudinal wave propagation experimental data and theory.

  1. No Change in Running Mechanics With Live High-Train Low Altitude Training in Elite Distance Runners.

    Science.gov (United States)

    Stickford, Abigail S L; Wilhite, Daniel P; Chapman, Robert F

    2017-01-01

    Investigations into ventilatory, metabolic, and hematological changes with altitude training have been completed; however, there is a lack of research exploring potential gait-kinematic changes after altitude training, despite a common complaint of athletes being a lack of leg "turnover" on return from altitude training. To determine if select kinematic variables changed in a group of elite distance runners after 4 wk of altitude training. Six elite male distance runners completed a 28-d altitude-training intervention in Flagstaff, AZ (2150 m), following a modified "live high-train low" model, wherein higherintensity runs were performed at lower altitudes (945-1150 m) and low-intensity sessions were completed at higher altitudes (1950-2850 m). Gait parameters were measured 2-9 d before departure to altitude and 1 to 2 d after returning to sea level at running speeds of 300-360 m/min. No differences were found in ground-contact time, swing time, or stride length or frequency after altitude training (P > .05). Running mechanics are not affected by chronic altitude training in elite distance runners. The data suggest that either chronic training at altitude truly has no effect on running mechanics or completing the live high-train low model of altitude training, where higher-velocity workouts are completed at lower elevations, mitigates any negative mechanical adaptations that may be associated with chronic training at slower speeds.

  2. MODELS-3 COMMUNITY MULTISCALE AIR QUALITY (CMAQ) MODEL AEROSOL COMPONENT 1: MODEL DESCRIPTION

    Science.gov (United States)

    The aerosol component of the Community Multiscale Air Quality (CMAQ) model is designed to be an efficient and economical depiction of aerosol dynamics in the atmosphere. The approach taken represents the particle size distribution as the superposition of three lognormal subdis...

  3. Stochastic daily precipitation model with a heavy-tailed component

    Science.gov (United States)

    Neykov, N. M.; Neytchev, P. N.; Zucchini, W.

    2014-09-01

    Stochastic daily precipitation models are commonly used to generate scenarios of climate variability or change on a daily timescale. The standard models consist of two components describing the occurrence and intensity series, respectively. Binary logistic regression is used to fit the occurrence data, and the intensity series is modeled using a continuous-valued right-skewed distribution, such as gamma, Weibull or lognormal. The precipitation series is then modeled using the joint density, and standard software for generalized linear models can be used to perform the computations. A drawback of these precipitation models is that they do not produce a sufficiently heavy upper tail for the distribution of daily precipitation amounts; they tend to underestimate the frequency of large storms. In this study, we adapted the approach of Furrer and Katz (2008) based on hybrid distributions in order to correct for this shortcoming. In particular, we applied hybrid gamma-generalized Pareto (GP) and hybrid Weibull-GP distributions to develop a stochastic precipitation model for daily rainfall at Ihtiman in western Bulgaria. We report the results of simulations designed to compare the models based on the hybrid distributions and those based on the standard distributions. Some potential difficulties are outlined.

  4. Education Knowledge System Combination Model Based on the Components

    Institute of Scientific and Technical Information of China (English)

    CHEN Lei; LI Dehua; LI Xiaojian; WU Chunxiang

    2007-01-01

    Resources are the base and core of education information, but current web education resources have no structure and it is still difficult to reuse them and make them can be self assembled and developed continually. According to the knowledge structure of course and text, the relation among knowledge points, knowledge units from three levels of media material, we can build education resource components, and build TKCM (Teaching Knowledge Combination Model) based on resource components. Builders can build and assemble knowledge system structure and make knowledge units can be self assembled, thus we can develop and consummate them continually. Users can make knowledge units can be self assembled and renewed, and build education knowledge system to satisfy users' demand under the form of education knowledge system.

  5. Interpretation of high-resolution low-altitude helicopter magnetometer surveys over sites contaminated with unexploded ordnance

    Science.gov (United States)

    Billings, Stephen; Wright, David

    2010-12-01

    Throughout the world, millions of acres of potentially productive land are contaminated with unexploded ordnance due to either past conflicts or to military training activities. Low-level helicopter magnetometry (HeliMag) is currently being used to rapidly survey large areas and identify regions that are potentially clear of hazardous munitions. One configuration currently in use comprises seven cesium vapor magnetometers, horizontally spaced 1.5 m apart and mounted on a boom several meters in front of a Bell 206L helicopter. Magnetometer data are collected at 400 Hz at altitudes as low as 1.5 m above the ground along transects spaced 7 meters apart. From this dense, high-resolution data, potential metallic targets as small as a 60 mm mortar are identified using manual and/or automatic target picking methods. The target picks are then used to estimate densities of potential contamination. 100% detection is generally not feasible, so that HeliMag is usually applied in a characterization rather than in a clearance mode. We describe a HeliMag survey collected over a UXO contaminated site at Yekau Lake, near Edmonton, Canada. The objective was to identify the location and extent of an 11.5 pound bomb target area at a former training range. The target density estimates derived from manual picks were strongly influenced by geology and clutter and did not reflect the underlying density of ordnance and ordnance related clutter. By fitting a dipole model to each target pick, and comparing it to the expected response of the target item, we could estimate the density of objects with similar size/shape to an 11.5 pound bomb. This analysis clearly identified an area of elevated contamination in the same region where 11.5 pound bombs were found during ground reconnaissance. In summary, the new methodology significantly improves the interpretability of HeliMag data when used for UXO site assessment.

  6. Four-component united-atom model of bitumen

    CERN Document Server

    Hansen, Jesper S; Nielsen, Erik; Dyre, Jeppe C; Schrøder, Thomas B

    2013-01-01

    We propose a four-component molecular model of bitumen. The model includes realistic chemical constituents and introduces a coarse-graining level that suppresses the highest frequency modes. Molecular dynamics simulations of the model are being carried out using Graphic-Processor-Units based software in time spans in order of microseconds, and this enables the study of slow relaxation processes characterizing bitumen. This paper focuses on the high-temperature dynamics as expressed through the mean-square displacement, the stress autocorrelation function, and rotational relaxation. The diffusivity of the individual molecules changes little as a function of temperature and reveals distinct dynamical time scales as a result of the different constituents in the system. Different time scales are also observed for the rotational relaxation. The stress autocorrelation function features a slow non-exponential decay for all temperatures studied. From the stress autocorrelation function, the shear viscosity and shear ...

  7. Modeling non-radial oscillations on components of close binaries

    Science.gov (United States)

    Latković, Olivera; Cséki, Attila

    2014-02-01

    We developed an advanced binary system model that includes stellar oscillations on one or both stars, with the goal of mode identification by fitting of the photometric light curves. The oscillations are modeled as perturbations of the local surface temperature and the local gravitational potential. In the case of tidally distorted stars, it is assumed that the pulsation axis coincides with the direction connecting the centers of the components rather than with the rotation axis. The mode identification method, originally devised by B. Bíró, is similar to eclipse mapping in that it utilizes the amplitude, phase and frequency modulation of oscillations during the eclipse; but the identification is achieved by grid-fitting of the observed light curve rather than by image reconstruction. The proposed model and the mode identification method have so far been tested on synthetic data with encouraging results.

  8. Comparison of analytical eddy current models using principal components analysis

    Science.gov (United States)

    Contant, S.; Luloff, M.; Morelli, J.; Krause, T. W.

    2017-02-01

    Monitoring the gap between the pressure tube (PT) and the calandria tube (CT) in CANDU® fuel channels is essential, as contact between the two tubes can lead to delayed hydride cracking of the pressure tube. Multifrequency transmit-receive eddy current non-destructive evaluation is used to determine this gap, as this method has different depths of penetration and variable sensitivity to noise, unlike single frequency eddy current non-destructive evaluation. An Analytical model based on the Dodd and Deeds solutions, and a second model that accounts for normal and lossy self-inductances, and a non-coaxial pickup coil, are examined for representing the response of an eddy current transmit-receive probe when considering factors that affect the gap response, such as pressure tube wall thickness and pressure tube resistivity. The multifrequency model data was analyzed using principal components analysis (PCA), a statistical method used to reduce the data set into a data set of fewer variables. The results of the PCA of the analytical models were then compared to PCA performed on a previously obtained experimental data set. The models gave similar results under variable PT wall thickness conditions, but the non-coaxial coil model, which accounts for self-inductive losses, performed significantly better than the Dodd and Deeds model under variable resistivity conditions.

  9. CORRECCION DE ILUMINACION PARA IMAGENES AEREAS DE CULTIVOS TOMADAS A BAJA ALTITUD ILLUMINATION CORRECTION FOR AERIAL AGRICULTURE IMAGES TAKEN AT LOW ALTITUDE

    Directory of Open Access Journals (Sweden)

    Juan Camilo Mejía Ospina

    2007-12-01

    Full Text Available En este trabajo se propone un método para realizar correcciones de color de imágenes aéreas de cultivos tomadas a baja altitud, en diferentes fechas, horas y condiciones de nubosidad. El método no requiere que la escena posea superficies o datos concretos que sirvan de estándar para realizar la corrección sobre la iluminación presente. El está basado en la técnica de constancia de color llamada gamut mapping, a la cual se le han hecho algunas variaciones aprovechando las características propias de las imágenes aéreas. El método permite, para imágenes capturadas bajo diferentes condiciones de iluminación, su normalización de modo que sean comparables entre ellas. En particular se aplicó a plantaciones de banano, pero puede ser extendido a cualquier tipo de cultivo, siempre que se utilice fotografía aérea de baja altitud. Se probó y validó usando imágenes simuladas debido a las dificultades encontradas durante la etapa de adquisición de imágenes reales.A new method is presented in order to carry out the color corrections of aerial agriculture images taken at low altitude, in different dates, times and conditions of cloudiness. The method does not require scene targets or specific data in order to develop the correction of the actual illumination. It is based on the constancy of color technique called gamut mapping, which was adapted to take advantage of the own characteristics of the aerial images. For images captured under different conditions of illumination, the method allows its normalization for comparison purposes. It was applied to banana plantations, but it can be extended to any type of agriculture images, registered by aerial images at low altitude. It was proven and validated using synthetic images because of some difficulties found during the acquisition stage of real images.

  10. A minimal model for two-component dark matter

    CERN Document Server

    Esch, Sonja; Yaguna, Carlos E

    2014-01-01

    We propose and study a new minimal model for two-component dark matter. The model contains only three additional fields, one fermion and two scalars, all singlets under the Standard Model gauge group. Two of these fields, one fermion and one scalar, are odd under a $Z_2$ symmetry that renders them simultaneously stable. Thus, both particles contribute to the observed dark matter density. This model resembles the union of the singlet scalar and the singlet fermionic models but it contains some new features of its own. We analyze in some detail its dark matter phenomenology. Regarding the relic density, the main novelty is the possible annihilation of one dark matter particle into the other, which can affect the predicted relic density in a significant way. Regarding dark matter detection, we identify a new contribution that can lead either to an enhancement or to a suppression of the spin-independent cross section for the scalar dark matter particle. Finally, we define a set of five benchmarks models compatibl...

  11. A multi-component evaporation model for beam melting processes

    Science.gov (United States)

    Klassen, Alexander; Forster, Vera E.; Körner, Carolin

    2017-02-01

    In additive manufacturing using laser or electron beam melting technologies, evaporation losses and changes in chemical composition are known issues when processing alloys with volatile elements. In this paper, a recently described numerical model based on a two-dimensional free surface lattice Boltzmann method is further developed to incorporate the effects of multi-component evaporation. The model takes into account the local melt pool composition during heating and fusion of metal powder. For validation, the titanium alloy Ti-6Al-4V is melted by selective electron beam melting and analysed using mass loss measurements and high-resolution microprobe imaging. Numerically determined evaporation losses and spatial distributions of aluminium compare well with experimental data. Predictions of the melt pool formation in bulk samples provide insight into the competition between the loss of volatile alloying elements from the irradiated surface and their advective redistribution within the molten region.

  12. A Multi-Component Model of Hodgkin's Lymphoma.

    Directory of Open Access Journals (Sweden)

    Martin S Staege

    Full Text Available Hodgkin's lymphoma is an example for a tumor with an extremely tight interaction of tumor cells with cells from the tumor micro-environment. These so-called bystander cells are not inert but interact actively with the tumor cells. Some of these cells support tumor growth by delivery of co-stimulating and anti-apoptotic signals ("helper cells". Other cells ("killer cells" are involved in the anti-tumor immune response which is obviously not efficient enough for tumor elimination. The activity of both helper cells and killer cells is regulated by additional cells in the stroma ("regulatory cells". The dynamic behavior of such multi-component systems is difficult to predict. In the present paper we propose a model that can be used for simulation of essential features of this system. In this model, tumor growth depends on (i presence of few cancer stem cells, (ii co-stimulation of cancer cells by the tumor stroma, (iii activity of regulatory cells that suppress killer cells without suppression of helper cells. The success of cytotoxic/cytostatic therapy in this model varies depending on the therapy-related toxicity for each of the cell populations. The model also allows the analysis of immunotherapeutic interventions. Under certain conditions, paradox enhancement of tumor growth can occur after therapeutic intervention. The model might be useful for the design of new treatment strategies for Hodgkin's lymphoma and other tumors with prominent tumor-stroma interaction.

  13. An Unmanned Airship Thermal Infrared Remote Sensing System for Low-Altitude and High Spatial Resolution Monitoring of Urban Thermal Environments: Integration and an Experiment

    Directory of Open Access Journals (Sweden)

    Peng Ren

    2015-10-01

    Full Text Available Satellite remote sensing data that lacks spatial resolution and timeliness is of limited ability to access urban thermal environment on a micro scale. This paper presents an unmanned airship low-altitude thermal infrared remote sensing system (UALTIRSS, which is composed of an unmanned airship, an onboard control and navigation subsystem, a task subsystem, a communication subsystem, and a ground-base station. Furthermore, an experimental method and an airborne-field experiment for collecting land surface temperature (LST were designed and conducted. The LST pattern within 0.8-m spatial resolution and with root mean square error (RMSE value of 2.63 °C was achieved and analyzed in the study region. Finally, the effects of surface types on the surrounding thermal environment were analyzed by LST profiles. Results show that the high thermal resolution imagery obtained from UALTIRSS can provide more detailed thermal information, which are conducive to classify fine urban material and assess surface urban heat island (SUHI. There is a significant positive correlation between the average LST of profiles and the percent impervious surface area (ISA% with R2 around 0.917. Overall, UALTIRSS and the retrieval method were proved to be low-cost and feasible for studying micro urban thermal environments.

  14. Low-altitude remote sensing and GIS-based analysis of cropmarks: classification of past thermal-contraction-crack polygons in central western Poland

    Science.gov (United States)

    Ewertowski, Marek W.; Kijowski, Andrzej; Szuman, Izabela; Tomczyk, Aleksandra M.; Kasprzak, Leszek

    2017-09-01

    The examination of low-altitude aerial photographs reveals the presence of more than 400 polygonal nets in central western Poland. Polygons range from 5 to almost 70 m in diameter. Based on the polygons' diameter and intersection angles, we identified seven main types of nets geometry. Based on ground verification, we interpreted them as past thermal-contraction-cracks, filled mostly with sand (i.e. sand-wedge casts). As favourable weather conditions and a proper land cover (i.e. cultivated land) are necessary for identifying polygonal nets, the observed number of polygons is probably much underestimated. The broad occurrence of former thermal-contraction-cracks' polygons indicates that continuous permafrost was widespread in central western Poland after the termination of the Last Glacial Maximum (LGM). Preliminary dating of the cracks' infilling as well as polygon geometry suggest that thermal-contraction-cracking occurred in several different phases and that a time frame of a few thousand years is sufficient to form complex, mature nets.

  15. 低空强爆炸中火球的一维数值模拟研究%Numerical Simulation of Fireball in Strong Explosion at Low Altitude

    Institute of Scientific and Technical Information of China (English)

    闫凯; 刘钰; 田宙

    2015-01-01

    对海平面环境下当量为1 Mt TNT的强爆炸进行一维辐射流体力学数值计算,得到了较为完整的火球扩张过程数值模拟结果。数值给出了火球不同发展阶段物质参数和辐射参数的空间分布,该结果与实际强爆炸中一些经验公式的计算结果吻合较好。给出了火球阵面和辐射功率随时间的变化关系,较合理地解释了低空强爆炸火球二次极大现象。%A one‐dimensional radiation hydrodynamics numerical computation was pres‐ented for a strong explosion at sea level ,of which the equivalent is 1 Mt TNT .The spatial distributions of material and radiation parameters in strong explosion , w hich reflect a integrate process of fireball evolution ,were given in terms of the simulation . The calculation results agree well with those of some empirical formulas .The results of optical observables‐radiation power versus time and fireball radius versus time were de‐scribed ,and the second maximum phenomenon of the fireball at low altitude was given .

  16. Effects of antioxidant vitamins on newborn and placental traits in gestations at high altitude: comparative study in high and low altitude native sheep.

    Science.gov (United States)

    Parraguez, Víctor H; Atlagich, Miljenko; Araneda, Oscar; García, Carlos; Muñoz, Andrés; De Los Reyes, Mónica; Urquieta, Bessie

    2011-01-01

    The present study evaluated the hypothesis that the effects of hypoxia on sheep pregnancies at high altitude (HA) are mediated by oxidative stress and that antioxidant vitamins may prevent these effects. Both HA native and newcomer ewes were maintained at an altitude of 3,589 m during mating and pregnancy. Control low altitude (LA) native ewes were maintained at sea level. Half of each group received daily oral supplements of vitamins C (500 mg) and E (350 IU) during mating and gestation. Near term, maternal plasma vitamin levels and oxidative stress biomarkers were measured. At delivery, lambs were weighed and measured, and placentas were recovered for macroscopic and microscopic evaluation. Vitamin concentrations in supplemented ewes were two- or threefold greater than in non-supplemented ewes. Plasma carbonyls and malondialdehyde in non-supplemented ewes were consistent with a state of oxidative stress, which was prevented by vitamin supplementation. Vitamin supplementation increased lamb birthweight and cotyledon number in both HA native and newcomer ewes, although placental weight and cotyledon surface were diminished. Placentas from vitamin-supplemented HA ewes were similar to those from ewes at sea level, making these placental traits (weight, number and diameter of cotyledons) similar to those from ewes at sea level. Vitamin supplementation had no effect on LA pregnancies. In conclusion, supplementation with vitamins C and E during pregnancy at HA prevents oxidative stress, improving pregnancy outcomes.

  17. Development of a low altitude airborne remote sensing system for supporting the processing of satellite remotely sensed data intended for archaeological investigations

    Science.gov (United States)

    Agapiou, Athos; Hadjimitsis, Diofantos G.; Georgopoulos, Andreas; Themistocleous, Kyriacos; Alexakis, Dimitris D.; Papadavid, George

    2012-10-01

    Earth observation techniques intended for archaeological research, such as satellite images and ground geophysical surveys are well established in the literature. In contrast, low altitude airborne systems for supporting archaeological research are still very limited. The "ICAROS" project, funded by the Cyprus Research Promotion Foundation, aims to develop an airborne system for archaeological investigations. The system will incorporate both a GER 1500 field spectroradiometer and NIR camera in a balloon system operated from the ground. The GER 1500 field spectroradiometer has the capability to record reflectance values from 400 nm up to 1050 nm (blue/green/red and NIR band). The Field of View (FOV) of the instrument is 4o while a calibrated spectralon panel will be used in order to minimize illumination errors during the data collection. Existing atmospheric conditions will be monitored using sun-photometer and meteorological station. The overall methodology of the project and the preliminary results from different cases studies in Cyprus are presented and discussed in this paper. Some practical problems are also discussed and the overall results are compared with satellite and ground measurements. Spectroradiometric measurements and NIR images will be taken from different heights from the balloon system. The results will be compared with different satellite images.

  18. Variability of observed low-altitude astronomical refraction (LAAR) from different geographic locations: progress toward a global map of LAAR variability.

    Science.gov (United States)

    Sampson, Russell D; Lozowski, Edward P; Machel, Hans G

    2005-09-20

    The variability of the astronomical refraction of the setting Sun as measured from Holetown, Barbados, West Indies, is compared to sunset refraction measured from Edmonton, Alberta, during the same time of year. At about 13 degrees N latitude, Holetown experiences a marine tropical climate, while Edmonton (53 degrees N) has a subarctic continental climate. The 17 sunsets recorded from Holetown between 27 December 2003, and 21 February 2004, and between 25 and 30 December 2004, show a mean astronomical refraction of 0 degrees .475 and standard deviation of 0 degrees .012. The 26 sunsets recorded from Edmonton between 31 December 1992, and 17 February 1993, show a mean astronomical refraction of 0 degrees .699 and standard deviation of 0 degrees .118. The Barbados mean is significantly less than the Edmonton mean, while the variability of the Barbados data is an order of magnitude less than the Edmonton data. The variability of refraction appears to be strongly correlated with the variability in the surface vertical temperature gradient recorded on the same day as the sunset observations. This suggests that mapping of the geographic distribution of low-altitude astronomical refraction variability could be based on climatology of the surface vertical temperature gradient.

  19. Understanding science teacher enhancement programs: Essential components and a model

    Science.gov (United States)

    Spiegel, Samuel Albert

    Researchers and practioners alike recognize that "the national goal that every child in the United States has access to high-quality school education in science and mathematics cannot be realized without the availability of effective professional development of teachers" (Hewson, 1997, p. 16). Further, there is a plethora of reports calling for the improvement of professional development efforts (Guskey & Huberman, 1995; Kyle, 1995; Loucks-Horsley, Hewson, Love, & Stiles, 1997). In this study I analyze a successful 3-year teacher enhancement program, one form of professional development, to: (1) identify essential components of an effective teacher enhancement program; and (2) create a model to identify and articulate the critical issues in designing, implementing, and evaluating teacher enhancement programs. Five primary sources of information were converted into data: (1) exit questionnaires, (2) exit surveys, (3) exit interview transcripts, (4) focus group transcripts, and (5) other artifacts. Additionally, a focus group was used to conduct member checks. Data were analyzed in an iterative process which led to the development of the list of essential components. The Components are categorized by three organizers: Structure (e.g., science research experience, a mediator throughout the program), Context (e.g., intensity, collaboration), and Participant Interpretation (e.g., perceived to be "safe" to examine personal beliefs and practices, actively engaged). The model is based on: (1) a 4-year study of a successful teacher enhancement program; (2) an analysis of professional development efforts reported in the literature; and (3) reflective discussions with implementors, evaluators, and participants of professional development programs. The model consists of three perspectives, cognitive, symbolic interaction, and organizational, representing different viewpoints from which to consider issues relevant to the success of a teacher enhancement program. These

  20. Blood components and OCT reflectivity evaluated in animal model.

    Science.gov (United States)

    Sonoda, Shozo; Sakamoto, Taiji; Shirasawa, Makoto; Yamashita, Takehiro; Uchino, Eisuke; Terasaki, Hiroto

    2014-12-01

    To see the relationship between blood components and optical coherence tomography (OCT) reflectivity using an animal model in which the aqueous humor was substituted by different experimental solutions without changing the integrity of the retina. The aqueous humor of an enucleated swine eye was replaced with plasma obtained from healthy volunteers. The OCT reflectivity of the anterior chamber filled with each plasma was calculated from individual OCT images, and was expressed by an arbitrary unit (AU). The concentration of blood components such as cholesterol, hemoglobin (Hb) and bilirubin of each individual was measured, and the correlation between each of them and the OCT reflectivity of aqueous humor in an enucleated swine eye was analyzed. Using the same model, the effects of the single plasma component on OCT reflectivity were examined. Blood samples were obtained from 24 individuals. OCT reflectivity was 30.68 ± 14.8 AU (average ± SD), ranging from 11.11 to 60.31 AU. OCT reflectivity correlated significantly with the concentration of triglycerides (R = 0.634, p = 0.001) and total cholesterol (R = 0.488, p = 0.015) using Spearman's rank correlation coefficient. While a partial correlation analysis showed that it correlated significantly with triglyceride (R = 0.60, p = 0.003), but not total cholesterol. OCT reflectivity was highest in a balanced salt solution (BSS) with Hb (average 42.05 AU), followed by fibrinogen (8.08 AU), bilirubin (6.12 AU) and γ-globulin (2.85 AU). Albumin did not increase the reflectivity of the BSS with a normal concentration (1.11 AU) compared to the control BSS alone (0.73 AU). OCT reflectivity was most strongly affected by the presence of triglycerides among the blood components. Some molecules such as Hb and fibrinogen significantly increase the OCT reflectivity. This information should be helpful for interpreting the OCT findings correctly.

  1. Three-Component Dust Models for Interstellar Extinction

    Indian Academy of Sciences (India)

    C. Muthumariappan

    2010-03-01

    Interstellar extinction curves obtained from the ‘extinction without standard’ method were used to constrain the dust characteristics in the mean ISM (V = 3.1), along the lines of sight through a high latitude diffuse molecular cloud towards HD 210121 (V = 2.1) and in a dense interstellar environment towards the cluster NGC 1977 (V = 6.42). We have used three-component dust models comprising silicate, graphite and very small carbonaceous grains (polycyclic aromatic hydrocarbons) following the grain size distributions introduced by Li & Draine in 2001. It is shown that oxygen, carbon and silicon abundances derived from our models are closer with the available elemental abundances for the dust grains in the ISM if F & G type stars atmospheric abundances are taken for the ISM than the solar. The importance of very small grains in modelling the variation of interstellar extinction curves has been investigated. Grain size distributions and elemental abundances locked up in dust are studied and compared at different interstellar environments using these three extinction curves. We present the albedo and the scattering asymmetry parameter evaluated from optical to extreme-UV wavelengths for the proposed dust models.

  2. 空管新技术在低空空域管理中应用分析%Application and analysis of new air traffic control technology in low altitude airspace management

    Institute of Scientific and Technical Information of China (English)

    李邢超

    2015-01-01

    随着低空空域内航空器数量的不断增加,飞行科目和类型也不断呈现出多样化的趋势,这给低空空域管理带来了亲所谓有的考验。现有的低空空域管理手段中存在一系列问题,阻碍了我国航空事业的发展。除了需要进行体制方面的变革外,空管高新技术的引用是提升低空空域管理水平的重要方式,有利于实现低空空域的资源利用率达到最高,推动我国航空业的持续快速发展。%With the increasing amount of aircraft in low altitude airspace,flight course and type also shows a trend of diversification,which give low altitude airspace management brought Pro called some test.There are a series of problems in the existing low altitude airspace management,which hinders the development of aviation industry in China..In addition to the need of system change,air traffic control(ATC) high technology reference is an important way to enhance the level of low altitude airspace management, conducive to the realization of low altitude airspace resource utilization rate reached the highest,and promote the sustained and rapid development of China's aviation industry.

  3. Modelling safety of multistate systems with ageing components

    Energy Technology Data Exchange (ETDEWEB)

    Kołowrocki, Krzysztof; Soszyńska-Budny, Joanna [Gdynia Maritime University, Department of Mathematics ul. Morska 81-87, Gdynia 81-225 Poland (Poland)

    2016-06-08

    An innovative approach to safety analysis of multistate ageing systems is presented. Basic notions of the ageing multistate systems safety analysis are introduced. The system components and the system multistate safety functions are defined. The mean values and variances of the multistate systems lifetimes in the safety state subsets and the mean values of their lifetimes in the particular safety states are defined. The multi-state system risk function and the moment of exceeding by the system the critical safety state are introduced. Applications of the proposed multistate system safety models to the evaluation and prediction of the safty characteristics of the consecutive “m out of n: F” is presented as well.

  4. Structures and components in galaxy clusters: observations and models

    CERN Document Server

    Bykov, A M; Ferrari, C; Forman, W R; Kaastra, J S; Klein, U; Markevitch, M; de Plaa, J

    2015-01-01

    Clusters of galaxies are the largest gravitationally bounded structures in the Universe dominated by dark matter. We review the observational appearance and physical models of plasma structures in clusters of galaxies. Bubbles of relativistic plasma which are inflated by supermassive black holes of AGNs, cooling and heating of the gas, large scale plasma shocks, cold fronts, non-thermal halos and relics are observed in clusters. These constituents are reflecting both the formation history and the dynamical properties of clusters of galaxies. We discuss X-ray spectroscopy as a tool to study the metal enrichment in clusters and fine spectroscopy of Fe X-ray lines as a powerful diagnostics of both the turbulent plasma motions and the energetics of the non-thermal electron populations. The knowledge of the complex dynamical and feedback processes is necessary to understand the energy and matter balance as well as to constrain the role of the non-thermal components of clusters.

  5. BWR Refill-Reflood Program, Task 4. 7 - model development: TRAC-BWR component models

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, Y K; Parameswaran, V; Shaug, J C

    1983-09-01

    TRAC (Transient Reactor Analysis Code) is a computer code for best-estimate analysis for the thermal hydraulic conditions in a reactor system. The development and assessment of the BWR component models developed under the Refill/Reflood Program that are necessary to structure a BWR-version of TRAC are described in this report. These component models are the jet pump, steam separator, steam dryer, two-phase level tracking model, and upper-plenum mixing model. These models have been implemented into TRAC-B02. Also a single-channel option has been developed for individual fuel-channel analysis following a system-response calculation.

  6. A Study on the Algorithm for Real Time Flight Conflict Detection and Resolution During Low-altitude Rescue%低空救援实时飞行的冲突探测与解脱算法研究∗

    Institute of Scientific and Technical Information of China (English)

    张明; 王磊; 王硕; 喻慧

    2016-01-01

    航空器冲突探测和解脱的实时计算对航空救援飞行安全意义重大。基于低空目视飞行规则,构建三维空域网格,采用时间窗理论分析了两航空器同高度飞行的时空冲突判定方法。依据救援目视飞行规则和航空器飞行性能约束,建立航空器 Agent 的可行路径集和基于网格划分的 Airspace模型,并根据航空器 Agent 的救援任务属性确定了优先级判定准则,对各个 Agent 模型在冲突顶点上的优先级进行判定。建立两航空器无冲突最优路径规划方法,计算 Agent 的无冲突路径。通过仿真验证,分析了飞行冲突的时间窗和区域,以及优先级下的无冲突路径,结果表明,本方法相对于非协作的冲突探测和解脱方法可以有效提高解脱效率,节约飞行时间146 s。%Real-time flight conflict detection and resolution algorithm is very important to aviation emergency rescue under the environment of complex low-altitude airspace.Based on low-altitude visual flight rules,this paper constructed a three-dimensional spatial grid,using the time window theory to analyze the temporal and spatial conflict of two flights. Based on visual flight rules during rescue and performance constraints of aircrafts,a feasible path set and Airspace model based on mesh generation for flight Agents are developed.Then priority of each Agent is identified at the conflicting point. Feasible non-conflict paths can be obtained by using the Agent model.Then an optimal path planning method is developed and the paths without any conflicts are created.The results are verified through a simulation,and the time window and the area of flight conflict,and the paths without any conflicts under different priority are analyzed.The results show that this method can provide a higher solution efficiency than non-collaborative methods,which can save a flight time of 146 s.

  7. Effect of Solar Cycle Activity on High Energy Proton of Inner Radiation Belt in the Low Altitude Region%太阳周期活动对低高度内辐射带高能质子的影响

    Institute of Scientific and Technical Information of China (English)

    师立勤; 林瑞淋; 刘四清; 郑惠南

    2012-01-01

    The NOAA-15 high energy proton observation from 1998 to 2011 is used to analyze the effect of solar cycle activity on high energy proton flux. The statistic research indicates that there is an inverse correlative relationship between the proton flux in inner radiation belt and solar activity. This anti-correlation is related to geomagnetic coordinates L and B, and more significant with the increasing of L and decreasing of B. There is also a phase lag between the solar activity and the proton flux. This hysteresis effect is more obvious in the region with smaller L or larger B. The lagcan reach one year in some regions. This hysteresis effect means it takes a long time to reach the dynamic balance between the source and the loss for the proton of inner radiation belt in the low altitude region. The unbalance between the source and loss is the reason why the intensity of proton flux at the same solar activity is different. The comparison with the result of AP8 model indicates the energetic proton flux from AP8 is higher than the satellite's observation in the region with large B, which suggests that the AP8 model may overstate the proton flux enhancement at inner radiation belt in the low altitude region if only the long-term variation of magnetic field is considered.%利用NOAA-15卫星1998年到2011年近13年的高能质子全向通量观测资料,分析了一个太阳活动周内,低高度内辐射带高能质子通量的分布变化特性及其物理原因,比较了观测结果与AP8模型的不同.研究表明,低高度内辐射带高能质子通量与太阳活动水平的反相关关系与磁壳参数L值及磁场B值有关;L值越低,B值越大的空间点,其高能质子通量与太阳活动水平的反向相关性越明显.高能质子通量随太阳活动水平的变化存在明显滞后现象,L值越高、B值越小的空间点,滞后现象就越明显,滞后严重时可以达到一年左右的时间;这种滞后现象反映出

  8. A fast and mobile system for registration of low-altitude visual and thermal aerial images using multiple small-scale UAVs

    Science.gov (United States)

    Yahyanejad, Saeed; Rinner, Bernhard

    2015-06-01

    The use of multiple small-scale UAVs to support first responders in disaster management has become popular because of their speed and low deployment costs. We exploit such UAVs to perform real-time monitoring of target areas by fusing individual images captured from heterogeneous aerial sensors. Many approaches have already been presented to register images from homogeneous sensors. These methods have demonstrated robustness against scale, rotation and illumination variations and can also cope with limited overlap among individual images. In this paper we focus on thermal and visual image registration and propose different methods to improve the quality of interspectral registration for the purpose of real-time monitoring and mobile mapping. Images captured by low-altitude UAVs represent a very challenging scenario for interspectral registration due to the strong variations in overlap, scale, rotation, point of view and structure of such scenes. Furthermore, these small-scale UAVs have limited processing and communication power. The contributions of this paper include (i) the introduction of a feature descriptor for robustly identifying corresponding regions of images in different spectrums, (ii) the registration of image mosaics, and (iii) the registration of depth maps. We evaluated the first method using a test data set consisting of 84 image pairs. In all instances our approach combined with SIFT or SURF feature-based registration was superior to the standard versions. Although we focus mainly on aerial imagery, our evaluation shows that the presented approach would also be beneficial in other scenarios such as surveillance and human detection. Furthermore, we demonstrated the advantages of the other two methods in case of multiple image pairs.

  9. 无人机低空遥感影像数据的获取与处理%Capture and processing of low altitude remote sensing images by UAV

    Institute of Scientific and Technical Information of China (English)

    鲁恒; 李永树; 何敬; 任志明

    2011-01-01

    The composition and technical indicators of low altitude remote sensing system based on unmanned aerial vehicle are introduced. The image data acquisition, image uniform color and triming, overlap calculation, panoramic mosaic image and orthophoto generation are addressed and for the reconstruction of earthquake-stricken areas to acquire the experimental data. Experimental results show that low-alti-tude UAV remote sensing system is fully able to meet the actual needs, and it can resolve the problems of multi-cloud region remote sensing image data acquisition, and has good potential in large scale mapping,three dimensional scene reconstruction, land-use survey and environmental monitoring areas.%介绍无人机低空遥感系统的构成和技术指标,论述影像数据的获取、影像匀色与裁边、重叠度计算、拼接全景影像图、生成正射影像等处理分析方法,并针对地震灾区重建数据获取进行实验.实验结果表明无人机低空遥感系统完全能满足实际需要,能解决多云雾地区遥感影像资料获取困难的问题,在大比例尺测图、三维景观重建、土地利用调查、环境监测等领域具有良好的应用前景.

  10. Effect of low altitude at the Dead Sea on exercise capacity and cardiopulmonary response to exercise in cystic fibrosis patients with moderate to severe lung disease.

    Science.gov (United States)

    Falk, Bareket; Nini, Asaph; Zigel, Levana; Yahav, Yaacov; Aviram, Micha; Rivlin, Joseph; Bentur, Lea; Avital, Avraham; Dotan, Raffy; Blau, Hannah

    2006-03-01

    Oxygen supplementation may improve exercise tolerance and the physiological response to exercise in cystic fibrosis (CF) patients. Elevated barometric pressure at low altitude is a simple means of increasing the quantity of inspired oxygen. Our objectives were to examine the effect of natural oxygen enrichment (at the Dead Sea, 396 m below sea level) on exercise capacity, and the physiological responses to maximal and submaximal exercise in CF patients. Patients were tested twice: at sea level (barometric pressure, 754 +/- 6 mmHg, mean +/- SD), and at the Dead Sea (barometric pressure, 791 +/- 3 mmHg), in a randomized crossover design. We studied 14 CF patients (6 females, 8 males), aged 15-45 years, with moderate to severe lung disease (mean forced expired volume in 1 sec = 50.0 +/- 11.2% predicted). Tests at each site included resting spirometry, anthropometry, a graded submaximal exercise test, a maximal exercise test on a treadmill, and a 6-min walk test. Tests were performed in identical order at both sites. Tests at the Dead Sea were performed 72 hr after arrival. No differences between sites were observed in lung function at rest. Peak oxygen consumption was significantly improved at the Dead Sea compared with sea level (1.68 +/- 0.73 vs. 1.57 +/- 0.74 l/min, respectively, P = 0.05), along with an improvement in the ventilatory equivalent for oxygen (41.2 +/- 6.3 vs. 46.1 +/- 7.1, respectively, P Dead Sea compared with sea level at all exercise intensities (P Dead Sea area may have physiological benefits for CF patients with moderate to severe lung disease.

  11. Estimation models of variance components for farrowing interval in swine

    Directory of Open Access Journals (Sweden)

    Aderbal Cavalcante Neto

    2009-02-01

    Full Text Available The main objective of this study was to evaluate the importance of including maternal genetic, common litter environmental and permanent environmental effects in estimation models of variance components for the farrowing interval trait in swine. Data consisting of 1,013 farrowing intervals of Dalland (C-40 sows recorded in two herds were analyzed. Variance components were obtained by the derivative-free restricted maximum likelihood method. Eight models were tested which contained the fixed effects(contemporary group and covariables and the direct genetic additive and residual effects, and varied regarding the inclusion of the maternal genetic, common litter environmental, and/or permanent environmental random effects. The likelihood-ratio test indicated that the inclusion of these effects in the model was unnecessary, but the inclusion of the permanent environmental effect caused changes in the estimates of heritability, which varied from 0.00 to 0.03. In conclusion, the heritability values obtained indicated that this trait appears to present no genetic gain as response to selection. The common litter environmental and the maternal genetic effects did not present any influence on this trait. The permanent environmental effect, however, should be considered in the genetic models for this trait in swine, because its presence caused changes in the additive genetic variance estimates.Este trabalho teve como objetivo principal avaliar a importância da inclusão dos efeitos genético materno, comum de leitegada e de ambiente permanente no modelo de estimação de componentes de variância para a característica intervalo de parto em fêmeas suínas. Foram utilizados dados que consistiam de 1.013 observações de fêmeas Dalland (C-40, registradas em dois rebanhos. As estimativas dos componentes de variância foram realizadas pelo método da máxima verossimilhança restrita livre de derivadas. Foram testados oito modelos, que continham os efeitos

  12. Computing Strongly Connected Components in the Streaming Model

    Science.gov (United States)

    Laura, Luigi; Santaroni, Federico

    In this paper we present the first algorithm to compute the Strongly Connected Components of a graph in the datastream model (W-Stream), where the graph is represented by a stream of edges and we are allowed to produce intermediate output streams. The algorithm is simple, effective, and can be implemented with few lines of code: it looks at each edge in the stream, and selects the appropriate action with respect to a tree T, representing the graph connectivity seen so far. We analyze the theoretical properties of the algorithm: correctness, memory occupation (O(n logn)), per item processing time (bounded by the current height of T), and number of passes (bounded by the maximal height of T). We conclude by presenting a brief experimental evaluation of the algorithm against massive synthetic and real graphs that confirms its effectiveness: with graphs with up to 100M nodes and 4G edges, only few passes are needed, and millions of edges per second are processed.

  13. Modeling QoS Parameters in Component-Based Systems

    Science.gov (United States)

    2004-08-01

    deployed components, begins with the system developer, willing to build a system, by presenting a query to the system generator . The query describes...is built using the system generator . If some of the components are not found then the system integrator can modify the system query by adding more

  14. Demonstration of Two Portable Scanning LiDAR Systems Flown at Low-Altitude for Investigating Coastal Sea Surface Topography

    Directory of Open Access Journals (Sweden)

    Jorg Hacker

    2011-09-01

    Full Text Available We demonstrate the efficacy of a commercial portable 2D laser scanner (operating at a wavelength close to 1,000 nm deployed from a fixed-wing aircraft for measuring the sea surface topography and wave profiles over coastal waters. The LiDAR instrumentation enabled simultaneous measurements of the 2D laser scanner with two independent inertial navigation units, and also simultaneous measurements with a more advanced 2D laser scanner (operating at a wavelength near 1,500 nm. The latter scanner is used routinely for accurately measuring terrestrial topography and was used as a benchmark in this study. We present examples of sea surface topography and wave profiles based on low altitude surveys (< ~300 m over coastal waters in the vicinity of Cape de Couedic, Kangaroo Island, South Australia and over the surf zone adjacent to the mouth of the Murray River, South Australia. Relative wave heights in the former survey are shown to be consistent with relative wave heights observed from a waverider buoy located near Cape de Couedic during the LiDAR survey. The sea surface topography of waves in the surf zone was successfully mapped with both laser scanners resolving relative wave height variations and fine structure of the sea surface to within approximately 10 cm. A topographic map of the sea surface referenced to the airborne sensor frame transforms to an accurate altimetry map which may be used with airborne electromagnetic instrumentation to provide an averaged altimetry covering a portion of the larger electromagnetic footprint. This averaged altimetry is deemed to be significantly more reliable as a measurement of altimetry than spot measurements using a nadir-looking laser altimeter and would therefore improve upon the use of airborne electromagnetic methods for bathymetric mapping in surf-zone waters. The aperture range of the scanner does not necessarily determine the swath. We observed that instead, the maximum swath at a given altitude was

  15. Modeling injection molding of net-shape active ceramic components.

    Energy Technology Data Exchange (ETDEWEB)

    Baer, Tomas (Gram Inc.); Cote, Raymond O.; Grillet, Anne Mary; Yang, Pin; Hopkins, Matthew Morgan; Noble, David R.; Notz, Patrick K.; Rao, Rekha Ranjana; Halbleib, Laura L.; Castaneda, Jaime N.; Burns, George Robert; Mondy, Lisa Ann; Brooks, Carlton, F.

    2006-11-01

    To reduce costs and hazardous wastes associated with the production of lead-based active ceramic components, an injection molding process is being investigated to replace the current machining process. Here, lead zirconate titanate (PZT) ceramic particles are suspended in a thermoplastic resin and are injected into a mold and allowed to cool. The part is then bisque fired and sintered to complete the densification process. To help design this new process we use a finite element model to describe the injection molding of the ceramic paste. Flow solutions are obtained using a coupled, finite-element based, Newton-Raphson numerical method based on the GOMA/ARIA suite of Sandia flow solvers. The evolution of the free surface is solved with an advanced level set algorithm. This approach incorporates novel methods for representing surface tension and wetting forces that affect the evolution of the free surface. Thermal, rheological, and wetting properties of the PZT paste are measured for use as input to the model. The viscosity of the PZT is highly dependent both on temperature and shear rate. One challenge in modeling the injection process is coming up with appropriate constitutive equations that capture relevant phenomenology without being too computationally complex. For this reason we model the material as a Carreau fluid and a WLF temperature dependence. Two-dimensional (2D) modeling is performed to explore the effects of the shear in isothermal conditions. Results indicate that very low viscosity regions exist near walls and that these results look similar in terms of meniscus shape and fill times to a simple Newtonian constitutive equation at the shear-thinned viscosity for the paste. These results allow us to pick a representative viscosity to use in fully three-dimensional (3D) simulation, which because of numerical complexities are restricted to using a Newtonian constitutive equation. Further 2D modeling at nonisothermal conditions shows that the choice of

  16. A PLM components monitoring framework for SMEs based on a PLM maturity model and FAHP methodology

    OpenAIRE

    Zhang, Haiqing; Sekhari, Aicha; Ouzrout, Yacine; Bouras, Abdelaziz

    2014-01-01

    Right PLM components selection and investments increase business advantages. This paper develops a PLM components monitoring framework to assess and guide PLM implementation in small and middle enterprises (SMEs). The framework builds upon PLM maturity models and decision-making methodology. PLM maturity model has the capability to analyze PLM functionalities and evaluate PLM components. A proposed PLM components maturity assessment (PCMA) model can obtain general maturity levels of PLM compo...

  17. 风场环境下运输机超低空空投安全性研究%On Safety of Ultra-Low Altitude Airdrop in Wind Field Circumstances

    Institute of Scientific and Technical Information of China (English)

    刘日; 孙秀霞; 李大东; 董文瀚

    2013-01-01

    基于矢量法推导了三维空间风场扰动下,超低空空投货台舱内移动飞行过程中六自由度动力学方程.考虑风速沿机身和翼展方向非均匀分布引起的附加气动力作用,提出了基于四点模型的风梯度建模与解算方法.通过动力学方程、气动导数构型,分析了货台运动和扰动风对空投载机品质特性的影响机理.仿真研究了紊流和侧风扰动下空投过程载机安全性和操纵性,结果表明:强紊流场会使载机载荷因数正负交替地振荡,干扰驾驶员操纵;强侧风环境下,载机可能因大幅滚转而使翼尖触地.%The six degrees of freedom (6D) dynamic equations for ultra-low altitude airdrop in three dimensional (3D) wind field were inferred based on vector method. The additional aerodynamics induced by the non-uniform distribution of the wind velocity across the body and wing span was taken into consideration. A general method was proposed for wind gradient modeling and computing based on four-point model. From dynamic functions and the aerodynamics derivative, the effects of the moving platform and the wind on the aircraft were analyzed. Simulation results show that: 1 ) hard turbulence can make the load factors oscillate with alternative signs, which may disturb the pilot operations, and 2 ) under strong crosswind, the aircraft wingtip may contact to earth as a radical lateral roll.

  18. Modeling Component-based Bragg gratings Application: tunable lasers

    Directory of Open Access Journals (Sweden)

    Hedara Rachida

    2011-09-01

    Full Text Available The principal function of a grating Bragg is filtering, which can be used in optical fibers based component and active or passive semi conductors based component, as well as telecommunication systems. Their ideal use is with lasers with fiber, amplifiers with fiber or Laser diodes. In this work, we are going to show the principal results obtained during the analysis of various types of grating Bragg by the method of the coupled modes. We then present the operation of DBR are tunable. The use of Bragg gratings in a laser provides single-mode sources, agile wavelength. The use of sampled grating increases the tuning range.

  19. Building Component Library: An Online Repository to Facilitate Building Energy Model Creation; Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, K.; Long, N.; Swindler, A.

    2012-05-01

    This paper describes the Building Component Library (BCL), the U.S. Department of Energy's (DOE) online repository of building components that can be directly used to create energy models. This comprehensive, searchable library consists of components and measures as well as the metadata which describes them. The library is also designed to allow contributors to easily add new components, providing a continuously growing, standardized list of components for users to draw upon.

  20. New approaches to the modelling of multi-component fuel droplet heating and evaporation

    KAUST Repository

    Sazhin, Sergei S

    2015-02-25

    The previously suggested quasi-discrete model for heating and evaporation of complex multi-component hydrocarbon fuel droplets is described. The dependence of density, viscosity, heat capacity and thermal conductivity of liquid components on carbon numbers n and temperatures is taken into account. The effects of temperature gradient and quasi-component diffusion inside droplets are taken into account. The analysis is based on the Effective Thermal Conductivity/Effective Diffusivity (ETC/ED) model. This model is applied to the analysis of Diesel and gasoline fuel droplet heating and evaporation. The components with relatively close n are replaced by quasi-components with properties calculated as average properties of the a priori defined groups of actual components. Thus the analysis of the heating and evaporation of droplets consisting of many components is replaced with the analysis of the heating and evaporation of droplets consisting of relatively few quasi-components. It is demonstrated that for Diesel and gasoline fuel droplets the predictions of the model based on five quasi-components are almost indistinguishable from the predictions of the model based on twenty quasi-components for Diesel fuel droplets and are very close to the predictions of the model based on thirteen quasi-components for gasoline fuel droplets. It is recommended that in the cases of both Diesel and gasoline spray combustion modelling, the analysis of droplet heating and evaporation is based on as little as five quasi-components.

  1. Modelling the effects of waste components on cement hydration

    NARCIS (Netherlands)

    Eijk, van R.J.; Brouwers, H.J.H.

    2001-01-01

    Ordinary Portland Cement (OPC) is often used for the solidification/stabilization (S/S) of waste containing heavy metals and salts. These waste components will precipitate in the form of insoluble compounds on to unreacted cement clinker grains preventing further hydration. In this study the long te

  2. Ecological, psychological, and cognitive components of reading difficulties: testing the component model of reading in fourth graders across 38 countries.

    Science.gov (United States)

    Chiu, Ming Ming; McBride-Chang, Catherine; Lin, Dan

    2012-01-01

    The authors tested the component model of reading (CMR) among 186,725 fourth grade students from 38 countries (45 regions) on five continents by analyzing the 2006 Progress in International Reading Literacy Study data using measures of ecological (country, family, school, teacher), psychological, and cognitive components. More than 91% of the differences in student difficulty occurred at the country (61%) and classroom (30%) levels (ecological), with less than 9% at the student level (cognitive and psychological). All three components were negatively associated with reading difficulties: cognitive (student's early literacy skills), ecological (family characteristics [socioeconomic status, number of books at home, and attitudes about reading], school characteristics [school climate and resources]), and psychological (students' attitudes about reading, reading self-concept, and being a girl). These results extend the CMR by demonstrating the importance of multiple levels of factors for reading deficits across diverse cultures.

  3. Virtual enterprise model for the electronic components business in the Nuclear Weapons Complex

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, T.J.; Long, K.S.; Sayre, J.A. [Sandia National Labs., Albuquerque, NM (United States); Hull, A.L. [Sandia National Labs., Livermore, CA (United States); Carey, D.A.; Sim, J.R.; Smith, M.G. [Allied-Signal Aerospace Co., Kansas City, MO (United States). Kansas City Div.

    1994-08-01

    The electronic components business within the Nuclear Weapons Complex spans organizational and Department of Energy contractor boundaries. An assessment of the current processes indicates a need for fundamentally changing the way electronic components are developed, procured, and manufactured. A model is provided based on a virtual enterprise that recognizes distinctive competencies within the Nuclear Weapons Complex and at the vendors. The model incorporates changes that reduce component delivery cycle time and improve cost effectiveness while delivering components of the appropriate quality.

  4. Virtual enterprise model for the electronic components business in the Nuclear Weapons Complex

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, T.J.; Long, K.S.; Sayre, J.A. [Sandia National Labs., Albuquerque, NM (United States); Hull, A.L. [Sandia National Labs., Livermore, CA (United States); Carey, D.A.; Sim, J.R.; Smith, M.G. [Allied-Signal Aerospace Co., Kansas City, MO (United States). Kansas City Div.

    1994-08-01

    The electronic components business within the Nuclear Weapons Complex spans organizational and Department of Energy contractor boundaries. An assessment of the current processes indicates a need for fundamentally changing the way electronic components are developed, procured, and manufactured. A model is provided based on a virtual enterprise that recognizes distinctive competencies within the Nuclear Weapons Complex and at the vendors. The model incorporates changes that reduce component delivery cycle time and improve cost effectiveness while delivering components of the appropriate quality.

  5. Comparing various multi-component global heliosphere models

    CERN Document Server

    Müller, H -R; Heerikhuisen, J; Izmodenov, V V; Scherer, K; Alexashov, D; Fahr, H -J

    2008-01-01

    Modeling of the global heliosphere seeks to investigate the interaction of the solar wind with the partially ionized local interstellar medium. Models that treat neutral hydrogen self-consistently and in great detail, together with the plasma, but that neglect magnetic fields, constitute a sub-category within global heliospheric models. There are several different modeling strategies used for this sub-category in the literature. Differences and commonalities in the modeling results from different strategies are pointed out. Plasma-only models and fully self-consistent models from four research groups, for which the neutral species is modeled with either one, three, or four fluids, or else kinetically, are run with the same boundary parameters and equations. They are compared to each other with respect to the locations of key heliospheric boundary locations and with respect to the neutral hydrogen content throughout the heliosphere. In many respects, the models' predictions are similar. In particular, the loca...

  6. Cosmological models with interacting components and mass-varying neutrinos

    CERN Document Server

    Collodel, Lucas G

    2012-01-01

    A model for a homogeneous and isotropic spatially flat Universe, composed of baryons, radiation, neutrinos, dark matter and dark energy is analyzed. We infer that dark energy (considered to behave as a scalar field) interacts with dark matter (either by the Wetterich model, or by the Anderson and Carroll model) and with neutrinos by a model proposed by Brookfield et al.. The latter is understood to have a mass-varying behavior. We show that for a very-softly varying field, both interacting models for dark matter give the same results. The models reproduce the expected red-shift performances of the present behavior of the Universe.

  7. Scalable Power-Component Models for Concept Testing

    Science.gov (United States)

    2011-08-16

    Technology: Permanent Magnet Brushless DC machine • Model : Self- generating torque-speed-efficiency map • Future improvements: Induction machine...unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Outline • Motivation and Scope • Integrated Starter Generator Model • Battery Model ...and systems engineering. • Scope: Scalable, generic MATLAB/Simulink models in three areas: – Electromechanical machines (Integrated Starter

  8. Models for describing the thermal characteristics of building components

    DEFF Research Database (Denmark)

    Jimenez, M.J.; Madsen, Henrik

    2008-01-01

    on the purpose of the modelling, existence of prior physical knowledge, the data and the available statistical tools. In this paper, a variety of models are outlined and compared, and a strong relationship among a large number of widely used linear and stationary stochastic models is mathematically demonstrated...

  9. Component-based Topological Data Model for Three-dimensional Geology Modeling

    Institute of Scientific and Technical Information of China (English)

    HOU Enke; WU Lixin; WU Yuhua; JU Tianyi

    2005-01-01

    On the study of the basic characteristics of geological objects and the special requirement for computing 3D geological model, this paper gives an object-oriented 3D topologic data model.In this model, the geological objects are divided into four object classes: point, line, area and volume.The volume class is further divided into four subclasses: the composite volume, the complex volume, the simple volume and the component.Twelve kinds of topological relations and the related data structures are designed for the geological objects.

  10. Musculoskeletal Modeling Component of the NASA Digital Astronaut Project

    Science.gov (United States)

    Lewandowski, B. E.; Pennline, J. A.; Stalker, A. R.; Mulugeta, L.; Myers, J. G.

    2011-01-01

    The NASA Digital Astronaut Project s (DAP) objective is to provide computational tools that support research of the physiological response to low gravity environments and analyses of how changes cause health and safety risks to the astronauts and to the success of the mission. The spaceflight risk associated with muscle atrophy is impaired performance due to reduced muscle mass, strength and endurance. Risks of early onset of osteoporosis and bone fracture are among the spaceflight risks associated with loss of bone mineral density. METHODS: Tools under development include a neuromuscular model, a biomechanical model and a bone remodeling model. The neuromuscular model will include models of neuromuscular drive, muscle atrophy, fiber morphology and metabolic processes as a function of time in space. Human movement will be modeled with the biomechanical model, using muscle and bone model parameters at various states. The bone remodeling model will allow analysis of bone turnover, loss and adaptation. A comprehensive trade study was completed to identify the current state of the art in musculoskeletal modeling. The DAP musculoskeletal models will be developed using a combination of existing commercial software and academic research codes identified in the study, which will be modified for use in human spaceflight research. These individual models are highly dependent upon each other and will be integrated together once they reach sufficient levels of maturity. ANALYSES: The analyses performed with these models will include comparison of different countermeasure exercises for optimizing effectiveness and comparison of task requirements and the state of strength and endurance of a crew member at a particular time in a mission. DISCUSSION: The DAP musculoskeletal model has the potential to complement research conducted on spaceflight induced changes to the musculoskeletal system. It can help with hypothesis formation, identification of causative mechanisms and

  11. Estimation and Modeling of Enceladus Plume Density Using Attitude Control Data Collected by the Cassini Spacecraft During Low-Altitude Enceladus Flybys

    Science.gov (United States)

    Wang, Eric K.; Lee, Allan Y.

    2011-01-01

    The Cassini spacecraft was launched on 15 October 1997. After an interplanetary cruise of almost seven years, it arrived at Saturn on June 30, 2004. Major science objectives of the Cassini mission include investigations of the configuration and dynamics of Saturn's magnetosphere, the structure and composition of the rings, the characterization of several of Saturn's icy satellites, and Titan's atmosphere constituent abundance

  12. Semi-holographic model including the radiation component

    CERN Document Server

    del Campo, Sergio; Magaña, Juan; Villanueva, J R

    2014-01-01

    In this letter we study the semi holographic model which corresponds to the radiative version of the model proposed by Zhang et al. (Phys. Lett. B 694 (2010), 177) and revisited by C\\'ardenas et al. (Mon. Not. Roy. Astron. Soc. 438 (2014), 3603). This inclusion makes the model more realistic, so allows us to test it with current observational data and then answer if the inconsistency reported by C\\'ardenas et al. is relaxed.

  13. Repeat, Low Altitude Measurements of Vegetation Status and Biomass Using Manned Aerial and UAS Imagery in a Piñon-Juniper Woodland

    Science.gov (United States)

    Krofcheck, D. J.; Lippitt, C.; Loerch, A.; Litvak, M. E.

    2015-12-01

    Measuring the above ground biomass of vegetation is a critical component of any ecological monitoring campaign. Traditionally, biomass of vegetation was measured with allometric-based approach. However, it is also time-consuming, labor-intensive, and extremely expensive to conduct over large scales and consequently is cost-prohibitive at the landscape scale. Furthermore, in semi-arid ecosystems characterized by vegetation with inconsistent growth morphologies (e.g., piñon-juniper woodlands), even ground-based conventional allometric approaches are often challenging to execute consistently across individuals and through time, increasing the difficulty of the required measurements and consequently the accuracy of the resulting products. To constrain the uncertainty associated with these campaigns, and to expand the extent of our measurement capability, we made repeat measurements of vegetation biomass in a semi-arid piñon-juniper woodland using structure-from-motion (SfM) techniques. We used high-spatial resolution overlapping aerial images and high-accuracy ground control points collected from both manned aircraft and multi-rotor UAS platforms, to generate digital surface model (DSM) for our experimental region. We extracted high-precision canopy volumes from the DSM and compared these to the vegetation allometric data, s to generate high precision canopy volume models. We used these models to predict the drivers of allometric equations for Pinus edulis and Juniperous monosperma (canopy height, diameter at breast height, and root collar diameter). Using this approach, we successfully accounted for the carbon stocks in standing live and standing dead vegetation across a 9 ha region, which contained 12.6 Mg / ha of standing dead biomass, with good agreement to our field plots. Here we present the initial results from an object oriented workflow which aims to automate the biomass estimation process of tree crown delineation and volume calculation, and partition

  14. PyCatch: Component based hydrological catchment modelling

    NARCIS (Netherlands)

    Lana-Renault, N.; Karssenberg, D.J.

    2013-01-01

    Dynamic numerical models are powerful tools for representing and studying environmental processes through time. Usually they are constructed with environmental modelling languages, which are high-level programming languages that operate at the level of thinking of the scientists. In this paper we pr

  15. Modeling and Analysis of Component Faults and Reliability

    DEFF Research Database (Denmark)

    Le Guilly, Thibaut; Olsen, Petur; Ravn, Anders Peter;

    2016-01-01

    that are automatically generated. The stochastic information on the faults is used to estimate the reliability of the fault affected system. The reliability is given with respect to properties of the system state space. We illustrate the process on a concrete example using the Uppaal model checker for validating...... the ideal system model and the fault modeling. Then the statistical version of the tool, UppaalSMC, is used to find reliability estimates.......This chapter presents a process to design and validate models of reactive systems in the form of communicating timed automata. The models are extended with faults associated with probabilities of occurrence. This enables a fault tree analysis of the system using minimal cut sets...

  16. Modelling elliptical galaxies phase-space constraints on two-component (gamma1,gamma2) models

    CERN Document Server

    Ciotti, L

    1999-01-01

    In the context of the study of the properties of the mutual mass distribution of the bright and dark matter in elliptical galaxies, present a family of two-component, spherical, self-consistent galaxy models, where one density distribution follows a gamma_1 profile, and the other a gamma_2 profile [(gamma_1,gamma_2) models], with different total masses and ``core'' radii. A variable amount of Osipkov-Merritt (radial) orbital anisotropy is allowed in both components. For these models, I derive analytically the necessary and sufficient conditions that the model parameters must satisfy in order to correspond to a physical system. Moreover, the possibility of adding a black hole at the center of radially anisotropic gamma models is discussed, determining analytically a lower limit of the anisotropy radius as a function of gamma. The analytical phase-space distribution function for (1,0) models is presented, together with the solution of the Jeans equations and the quantities entering the scalar virial theorem. It...

  17. Architecture and Framework Design of Detection Fusion System for Low-altitude Target%低空目标检测融合系统的结构与框架设计

    Institute of Scientific and Technical Information of China (English)

    权宏伟; 彭冬亮

    2014-01-01

    In complex battlefield environment,the traditional radar system could hardly detect low-altitude targets. Considering the features of low-altitude target such as signal weakness,strong background clutter,high maneuverability,a method to designing architecture and framework of detection fusion system for low-altitude target is proposed. The robustness and anti-destroy ability of the fusion system is enhanced by introducing the hybrid structure. In aspects of sensors management and distribution,detection and tracking fusion,joint detection and tracking with recognition,the performance optimization of the fusion system can be achieved by dynamically evaluating and optimizing each module.%在复杂战场环境下,传统的雷达系统很难检测到低空目标。针对低空目标信号微弱、背景杂波干扰强以及目标高机动性等特点,提出了一种低空目标检测融合系统的结构与框架设计方法。该融合系统通过引入混合式结构,增加了系统的鲁棒性与抗摧毁能力。在融合系统的传感器管理与分配环节,目标检测与跟踪方法融合环节,联合检测、跟踪与识别环节,通过对各模块的性能评估和动态优化,实现低空目标融合检测与跟踪性能的最优化。

  18. Component-Based Model for Single-Plate Shear Connections with Pretension and Pinched Hysteresis.

    Science.gov (United States)

    Weigand, Jonathan M

    2017-02-01

    Component-based connection models provide a natural framework for modeling the complex behaviors of connections under extreme loads by capturing both the individual behaviors of the connection components, such as the bolt, shear plate, and beam web, and the complex interactions between those components. Component-based models also provide automatic coupling between the in-plane flexural and axial connection behaviors, a feature that is essential for modeling the behavior of connections under column removal. This paper presents a new component-based model for single-plate shear connections that includes the effects of pre-tension in the bolts and provides the capability to model standard and slotted holes. The component-based models are exercised under component-level deformations calculated from the connection demands via a practical rigid-body displacement model, so that the results of the presented modeling approach remains hand-calculable. Validation cases are presented for connections subjected to both seismic and column removal loading. These validation cases show that the component-based model is capable of predicting the response of single-plate shear connections for both seismic and column removal loads.

  19. Lorenz Wind Disturbance Model Based on Grey Generated Components

    Directory of Open Access Journals (Sweden)

    Yagang Zhang

    2014-11-01

    Full Text Available In order to meet the needs of wind speed prediction in wind farms, we consider the influence of random atmospheric disturbances on wind variations. Considering a simplified fluid convection mode, a Lorenz system can be employed as an atmospheric disturbance model. Here Lorenz disturbance is defined as the European norm of the solutions of the Lorenz equation. Grey generating and accumulated generating models are employed to explore the relationship between wind speed and its related disturbance series. We conclude that a linear or quadric polynomial generating model are optimal through the verification of short-term wind speed prediction in the Sotavento wind farm. The new proposed model not only greatly improves the precision of short-term wind speed prediction, but also has great significance for the maintenance and stability of wind power system operation.

  20. Lorenz Wind Disturbance Model Based on Grey Generated Components

    OpenAIRE

    Yagang Zhang; Jingyun Yang; Kangcheng Wang; Yinding Wang

    2014-01-01

    In order to meet the needs of wind speed prediction in wind farms, we consider the influence of random atmospheric disturbances on wind variations. Considering a simplified fluid convection mode, a Lorenz system can be employed as an atmospheric disturbance model. Here Lorenz disturbance is defined as the European norm of the solutions of the Lorenz equation. Grey generating and accumulated generating models are employed to explore the relationship between wind speed and its related disturban...

  1. The dynamic cusp at low altitudes: A case study utilizing Viking, DMSP-F7 and Sondrestrom incoherent scatter radar observations

    Science.gov (United States)

    Watermann, J.; De La Beaujardiere, O.; Lummerzheim, D.; Woch, J.; Newell, P. T.; Potemra, T. A.; Rich, F. J.; Shapshak, M.

    1994-01-01

    Coincident multi-instrument magnetospheric and ionospheric observations have made it possible to determine the position of the ionospheric footprint of the magnetospheric cusp and to monitor its evolution over time. The data used include charged particle and magnetic field measurements from the Earth-orbiting Viking and DMSP-F7 satellites, electric field measurements from Viking, interplanetary magnetic field and plasma data from IMP-8, and Sondrestrom incoherent scatter radar observations of the ionospheric plasma density, temperature, and convection. Viking detected cusp precipitation poleward of 75.5 deg invariant latitude. The ionospheric response to the observed electron precipitation was simulated using an auroral model. It predicts enhanced plasma density and elevated electron temperature in the upper E- and F- regions. Sondrestrom radar observations are in agreement with the predictions. The radar detected a cusp signature on each of five consecutive antenna elevation scans covering 1.2h local time. The cusp appeared to be about 2 deg invariant latitude wide, and its ionospheric footprint shifted equatorward by nearly 2 deg during this time, possibly influenced by an overall decrease in the interplanetary magnetic field (IMF) B(sub z) component. The radar plasma drift data and the Viking magnetic and electric field data suggest that the cusp was associated with a continuous, rather than a patchy, merging between the IMF and the geomagnetic field.

  2. Imaging lipid distributions in model monolayers by ToF-SIMS with selectively deuterated components and principal components analysis

    Energy Technology Data Exchange (ETDEWEB)

    Biesinger, Mark C. [Surface Science Western, University of Western Ontario, London, Ont., N6A 5B7 (Canada)]. E-mail: biesingr@uwo.ca; Miller, David J. [Surface Science Western, University of Western Ontario, London, Ont., N6A 5B7 (Canada); Department of Chemistry, University of Western Ontario, London, Ont., N6A 5B7 (Canada); Harbottle, Robert R. [Department of Chemistry, University of Western Ontario, London, Ont., N6A 5B7 (Canada); Possmayer, Fred [Department of Obstetrics and Gynecology, University of Western Ontario, London, Ont., N6A 5B7 (Canada); McIntyre, N. Stewart [Surface Science Western, University of Western Ontario, London, Ont., N6A 5B7 (Canada); Department of Chemistry, University of Western Ontario, London, Ont., N6A 5B7 (Canada); Petersen, Nils O. [National Institute for Nanotechnology and Department of Chemistry, University of Alberta W6-017 ECERF Bldg, 9107-116th Street, Edmonton, Alta., T6G 2V4 (Canada)

    2006-07-30

    Time of flight secondary ion mass spectrometry (ToF-SIMS) provides the capability to image the distribution of molecular ions and their associated fragments that are emitted from monolayer films. ToF-SIMS can be applied to the analysis of monolayers of complex lipid mixtures that act as a model to understand the organization of cell membranes into solid-like domains called lipid rafts. The ability to determine the molecular distribution of lipids using ToF-SIMS in monolayer films is also important in studies of the function of pulmonary surfactant. One of the limitations of the use of ToF-SIMS to studies of complex lipid mixtures found in biological systems, arises from the similarity of the mass fragments that are emitted from the components of the lipid mixture. The use of selectively deuterated components in a mixture overcomes this limitation and results in an unambiguous assignment of specific lipids to particular surface domains. The use of deuterium labeling to identify specific lipids in a multi-component mixture can be done by the deuteration of a single lipid or by the addition of more than one lipid with selectively deuterated components. The incorporation of deuterium into the lipid chains does not alter the miscibility or phase behavior of these systems. The use of deuterium labeling to identify lipids and determine their distribution in monolayer films will be demonstrated using two biological systems. Principal components analysis (PCA) is used to further analyze these deuterated systems checking for the origin of the various mass fragments present.

  3. Simultaneous optimal estimates of fixed effects and variance components in the mixed model

    Institute of Scientific and Technical Information of China (English)

    WU Mixia; WANG Songgui

    2004-01-01

    For a general linear mixed model with two variance components, a set of simple conditions is obtained, under which, (i) the least squares estimate of the fixed effects and the analysis of variance (ANOVA) estimates of variance components are proved to be uniformly minimum variance unbiased estimates simultaneously; (ii) the exact confidence intervals of the fixed effects and uniformly optimal unbiased tests on variance components are given; (iii) the exact probability expression of ANOVA estimates of variance components taking negative value is obtained.

  4. System level modeling and component level control of fuel cells

    Science.gov (United States)

    Xue, Xingjian

    This dissertation investigates the fuel cell systems and the related technologies in three aspects: (1) system-level dynamic modeling of both PEM fuel cell (PEMFC) and solid oxide fuel cell (SOFC); (2) condition monitoring scheme development of PEM fuel cell system using model-based statistical method; and (3) strategy and algorithm development of precision control with potential application in energy systems. The dissertation first presents a system level dynamic modeling strategy for PEM fuel cells. It is well known that water plays a critical role in PEM fuel cell operations. It makes the membrane function appropriately and improves the durability. The low temperature operating conditions, however, impose modeling difficulties in characterizing the liquid-vapor two phase change phenomenon, which becomes even more complex under dynamic operating conditions. This dissertation proposes an innovative method to characterize this phenomenon, and builds a comprehensive model for PEM fuel cell at the system level. The model features the complete characterization of multi-physics dynamic coupling effects with the inclusion of dynamic phase change. The model is validated using Ballard stack experimental result from open literature. The system behavior and the internal coupling effects are also investigated using this model under various operating conditions. Anode-supported tubular SOFC is also investigated in the dissertation. While the Nernst potential plays a central role in characterizing the electrochemical performance, the traditional Nernst equation may lead to incorrect analysis results under dynamic operating conditions due to the current reverse flow phenomenon. This dissertation presents a systematic study in this regard to incorporate a modified Nernst potential expression and the heat/mass transfer into the analysis. The model is used to investigate the limitations and optimal results of various operating conditions; it can also be utilized to perform the

  5. Feedback loops and temporal misalignment in component-based hydrologic modeling

    Science.gov (United States)

    Elag, Mostafa M.; Goodall, Jonathan L.; Castronova, Anthony M.

    2011-12-01

    In component-based modeling, a complex system is represented as a series of loosely integrated components with defined interfaces and data exchanges that allow the components to be coupled together through shared boundary conditions. Although the component-based paradigm is commonly used in software engineering, it has only recently been applied for modeling hydrologic and earth systems. As a result, research is needed to test and verify the applicability of the approach for modeling hydrologic systems. The objective of this work was therefore to investigate two aspects of using component-based software architecture for hydrologic modeling: (1) simulation of feedback loops between components that share a boundary condition and (2) data transfers between temporally misaligned model components. We investigated these topics using a simple case study where diffusion of mass is modeled across a water-sediment interface. We simulated the multimedia system using two model components, one for the water and one for the sediment, coupled using the Open Modeling Interface (OpenMI) standard. The results were compared with a more conventional numerical approach for solving the system where the domain is represented by a single multidimensional array. Results showed that the component-based approach was able to produce the same results obtained with the more conventional numerical approach. When the two components were temporally misaligned, we explored the use of different interpolation schemes to minimize mass balance error within the coupled system. The outcome of this work provides evidence that component-based modeling can be used to simulate complicated feedback loops between systems and guidance as to how different interpolation schemes minimize mass balance error introduced when components are temporally misaligned.

  6. Modeling of a remote inspection system for NSSS components

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yoo Rark; Kim, Jae Hee; Lee, Jae Cheol

    2003-03-01

    Safety inspection for safety-critical unit of nuclear power plant has been processed using off-line technology. Thus we can not access safety inspection system and inspection data via network such as internet. We are making an on-line control and data access system based on WWW and JAVA technologies which can be used during plant operation to overcome these problems. Users can access inspection systems and inspection data only using web-browser. This report discusses about analysis of the existing remote system and essential techniques such as Web, JAVA, client/server model, and multi-tier model. This report also discusses about a system modeling that we have been developed using these techniques and provides solutions for developing an on-line control and data access system.

  7. Stochastic Models of Defects in Wind Turbine Drivetrain Components

    DEFF Research Database (Denmark)

    Rafsanjani, Hesam Mirzaei; Sørensen, John Dalsgaard

    2013-01-01

    of the drivetrain will lead to substantial economic losses such as cost of lost energy production, cost of repairs, cost of crew and cost of transportation. For offshore wind turbines, the marine environment affects the repair & maintenance process and in some case because of the rush environment, the maintenance...... team cannot operate properly and the wind turbine does not work for several days and consequently the cost of lost energy increases drastically. In this paper is presented stochastic models for fatigue failure based on test data and the accuracy of the models are compared....

  8. A Component-Based Software Configuration Management Model and Its Supporting System

    Institute of Scientific and Technical Information of China (English)

    梅宏; 张路; 杨芙清

    2002-01-01

    Software configuration management (SCM) is an important key technology in software development. Component-based software development (CBSD) is an emerging paradigm in software development. However, to apply CBSD effectively in real world practice,supporting SCM in CBSD needs to be further investigated. In this paper, the objects that need to be managed in CBSD is analyzed and a component-based SCM model is presented. In this model, components, as the integral logical constituents in a system, are managed as the basic configuration items in SCM, and the relationships between/among components are defined and maintained. Based on this model, a configuration management system is implemented.

  9. Confidence intervals for intraclass correlation coefficients in variance components models

    NARCIS (Netherlands)

    Demetrashvili, Nino; Wit, Ernst C; Van Den Heuvel, Edwin R.

    2016-01-01

    Confidence intervals for intraclass correlation coefficients in agreement studies with continuous outcomes are model-specific and no generic approach exists. This paper provides two generic approaches for intraclass correlation coefficients of the form -' q = 1 Q σ q 2 / (-' q = 1 Q σ q 2 + -' p = Q

  10. Confidence intervals for intraclass correlation coefficients in variance components models

    NARCIS (Netherlands)

    Demetrashvili, Nino; Wit, Ernst C; Van Den Heuvel, Edwin R.

    2016-01-01

    Confidence intervals for intraclass correlation coefficients in agreement studies with continuous outcomes are model-specific and no generic approach exists. This paper provides two generic approaches for intraclass correlation coefficients of the form -' q = 1 Q σ q 2 / (-' q = 1 Q σ q 2 + -' p = Q

  11. Mathematical Model for Multicomponent Adsorption Equilibria Using Only Pure Component Data

    DEFF Research Database (Denmark)

    Marcussen, Lis

    2000-01-01

    A mathematical model for nonideal adsorption equilibria in multicomponent mixtures is developed. It is applied with good results for pure substances and for prediction of strongly nonideal multicomponent equilibria using only pure component data. The model accounts for adsorbent...

  12. Modelling the Epistemic Uncertainty in the Vulnerability Assessment Component of an Earthquake Loss Model

    Science.gov (United States)

    Crowley, H.; Modica, A.

    2009-04-01

    Loss estimates have been shown in various studies to be highly sensitive to the methodology employed, the seismicity and ground-motion models, the vulnerability functions, and assumed replacement costs (e.g. Crowley et al., 2005; Molina and Lindholm, 2005; Grossi, 2000). It is clear that future loss models should explicitly account for these epistemic uncertainties. Indeed, a cause of frequent concern in the insurance and reinsurance industries is precisely the fact that for certain regions and perils, available commercial catastrophe models often yield significantly different loss estimates. Of equal relevance to many users is the fact that updates of the models sometimes lead to very significant changes in the losses compared to the previous version of the software. In order to model the epistemic uncertainties that are inherent in loss models, a number of different approaches for the hazard, vulnerability, exposure and loss components should be clearly and transparently applied, with the shortcomings and benefits of each method clearly exposed by the developers, such that the end-users can begin to compare the results and the uncertainty in these results from different models. This paper looks at an application of a logic-tree type methodology to model the epistemic uncertainty in the vulnerability component of a loss model for Tunisia. Unlike other countries which have been subjected to damaging earthquakes, there has not been a significant effort to undertake vulnerability studies for the building stock in Tunisia. Hence, when presented with the need to produce a loss model for a country like Tunisia, a number of different approaches can and should be applied to model the vulnerability. These include empirical procedures which utilise observed damage data, and mechanics-based methods where both the structural characteristics and response of the buildings are analytically modelled. Some preliminary applications of the methodology are presented and discussed

  13. Forecasting Daily Time Series using Periodic Unobserved Components Time Series Models

    NARCIS (Netherlands)

    Koopman, Siem Jan; Ooms, Marius

    2004-01-01

    We explore a periodic analysis in the context of unobserved components time series models that decompose time series into components of interest such as trend and seasonal. Periodic time series models allow dynamic characteristics to depend on the period of the year, month, week or day. In the stand

  14. Team automata : a formal approach to the modeling of collaboration between system components

    NARCIS (Netherlands)

    Beek, Maurice Henri ter

    2003-01-01

    This thesis studies formal aspects of team automata, a mathematical framework introduced in 1997 by C.A. Ellis to model components of groupware systems and their interconnections. We focus on the flexibility that team automata offer when modeling collaboration between system components

  15. Forecasting Daily Time Series using Periodic Unobserved Components Time Series Models

    NARCIS (Netherlands)

    Koopman, Siem Jan; Ooms, Marius

    2004-01-01

    We explore a periodic analysis in the context of unobserved components time series models that decompose time series into components of interest such as trend and seasonal. Periodic time series models allow dynamic characteristics to depend on the period of the year, month, week or day. In the

  16. Comprehensive FDTD modelling of photonic crystal waveguide components

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Borel, Peter Ingo; Frandsen, Lars Hagedorn

    2004-01-01

    Planar photonic crystal waveguide structures have been modelled using the finite-difference-time-domain method and perfectly matched layers have been employed as boundary conditions. Comprehensive numerical calculations have been performed and compared to experimentally obtained transmission...... spectra for various photonic crystal waveguides. It is found that within the experimental fabrication tolerances the calculations correctly predict the measured transmission levels and other major transmission features....

  17. Five-component propagation model for steam explosion analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y.; Moriyama, Kiyofumi; Park, H.S.; Maruyama, Yu; Sugimoto, Jun [Severe Accident Research Laboratory, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)

    1999-07-01

    A five-field simulation code JASMINE-pro has been developed at JAERI for the calculation of the propagation and explosion phase of steam explosions. The basic equations and the constitutive relationships specifically utilized in the propagation models in the code are introduced in this paper. Some calculations simulating the KROTOS 1D and 2D steam explosion experiments are also stated in the paper to show the present capability of the code. (author)

  18. Comprehensive FDTD modelling of photonic crystal waveguide components

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Borel, Peter Ingo; Frandsen, Lars Hagedorn;

    2004-01-01

    Planar photonic crystal waveguide structures have been modelled using the finite-difference-time-domain method and perfectly matched layers have been employed as boundary conditions. Comprehensive numerical calculations have been performed and compared to experimentally obtained transmission...... spectra for various photonic crystal waveguides. It is found that within the experimental fabrication tolerances the calculations correctly predict the measured transmission levels and other major transmission features....

  19. Modeling media as latent semantics based on cognitive components

    DEFF Research Database (Denmark)

    Petersen, Michael Kai

    dimensionality. While top-down, patterns of emotional categorization emerge by defining term vector distances to affective adjectives, that constrain the latent semantic structures according to the neurophysiological dimensions of valence and arousal. The thesis thus combines elements of machine learning...... with aspects of cognitive linguistics that potentially could be utilized in applications ranging from information retrieval and media personalization, to emotional brand building or neuroscientific modeling of syntax and semantics....

  20. Genetic and Modeling Approaches Reveal Distinct Components of Impulsive Behavior.

    Science.gov (United States)

    Nautiyal, Katherine M; Wall, Melanie M; Wang, Shuai; Magalong, Valerie M; Ahmari, Susanne E; Balsam, Peter D; Blanco, Carlos; Hen, René

    2017-01-18

    Impulsivity is an endophenotype found in many psychiatric disorders including substance use disorders, pathological gambling, and attention deficit hyperactivity disorder. Two behavioral features often considered in impulsive behavior are behavioral inhibition (impulsive action) and delayed gratification (impulsive choice). However, the extent to which these behavioral constructs represent distinct facets of behavior with discrete biological bases is unclear. To test the hypothesis that impulsive action and impulsive choice represent statistically independent behavioral constructs in mice, we collected behavioral measures of impulsivity in a single cohort of mice using well-validated operant behavioral paradigms. Mice with manipulation of serotonin 1B receptor (5-HT1BR) expression were included as a model of disordered impulsivity. A factor analysis was used to characterize correlations between the measures of impulsivity and to identify covariates. Using two approaches, we dissociated impulsive action from impulsive choice. First, the absence of 5-HT1BRs caused increased impulsive action, but not impulsive choice. Second, based on an exploratory factor analysis, a two-factor model described the data well, with measures of impulsive action and choice separating into two independent factors. A multiple-indicator multiple-causes analysis showed that 5-HT1BR expression and sex were significant covariates of impulsivity. Males displayed increased impulsivity in both dimensions, whereas 5-HT1BR expression was a predictor of increased impulsive action only. These data support the conclusion that impulsive action and impulsive choice are distinct behavioral phenotypes with dissociable biological influences that can be modeled in mice. Our work may help inform better classification, diagnosis, and treatment of psychiatric disorders, which present with disordered impulsivity.Neuropsychopharmacology advance online publication, 18 January 2017; doi:10.1038/npp.2016.277.

  1. Kernel Principal Component Analysis for Stochastic Input Model Generation (PREPRINT)

    Science.gov (United States)

    2010-08-17

    c ( )d Fig. 13. Contour of saturation at 0.2 PVI : MC mean (a) and variance (b) from experimental samples; MC mean (c) and variance (d) from PC...realizations. The contour plots of saturation at 0.2 PVI are given in Fig. 13. PVI represents dimensionless time and is computed as PVI = ∫ Q dt/Vp...stochastic input model provides a fast way to generate many realizations, which are consistent, in a useful sense, with the experimental data. PVI M ea n

  2. Dynamic modeling of solar dynamic components and systems

    Science.gov (United States)

    Hochstein, John I.; Korakianitis, T.

    1992-09-01

    The purpose of this grant was to support NASA in modeling efforts to predict the transient dynamic and thermodynamic response of the space station solar dynamic power generation system. In order to meet the initial schedule requirement of providing results in time to support installation of the system as part of the initial phase of space station, early efforts were executed with alacrity and often in parallel. Initially, methods to predict the transient response of a Rankine as well as a Brayton cycle were developed. Review of preliminary design concepts led NASA to select a regenerative gas-turbine cycle using a helium-xenon mixture as the working fluid and, from that point forward, the modeling effort focused exclusively on that system. Although initial project planning called for a three year period of performance, revised NASA schedules moved system installation to later and later phases of station deployment. Eventually, NASA selected to halt development of the solar dynamic power generation system for space station and to reduce support for this project to two-thirds of the original level.

  3. Modelling insights on the partition of evapotranspiration components across biomes

    Science.gov (United States)

    Fatichi, Simone; Pappas, Christoforos

    2017-04-01

    Recent studies using various methodologies have found a large variability (from 35 to 90%) in the ratio of transpiration to total evapotranspiration (denoted as T:ET) across biomes or even at the global scale. Concurrently, previous results suggest that T:ET is independent of mean precipitation and has a positive correlation with Leaf Area Index (LAI). We used the mechanistic ecohydrological model, T&C, with a refined process-based description of soil resistance and a detailed treatment of canopy biophysics and ecophysiology, to investigate T:ET across multiple biomes. Contrary to observation-based estimates, simulation results highlight a well-constrained range of mean T:ET across biomes that is also robust to perturbations of the most sensitive parameters. Simulated T:ET was confirmed to be independent of average precipitation, while it was found to be uncorrelated with LAI across biomes. Higher values of LAI increase evaporation from interception but suppress ground evaporation with the two effects largely cancelling each other in many sites. These results offer mechanistic, model-based, evidence to the ongoing research about the range of T:ET and the factors affecting its magnitude across biomes.

  4. The Component Slope Linear Model for Calculating Intensive Partial Molar Properties: Application to Waste Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, Jacob G. [Washington River Protection Solutions, Richland, WA (United States)

    2013-01-11

    Partial molar properties are the changes occurring when the fraction of one component is varied while the fractions of all other component mole fractions change proportionally. They have many practical and theoretical applications in chemical thermodynamics. Partial molar properties of chemical mixtures are difficult to measure because the component mole fractions must sum to one, so a change in fraction of one component must be offset with a change in one or more other components. Given that more than one component fraction is changing at a time, it is difficult to assign a change in measured response to a change in a single component. In this study, the Component Slope Linear Model (CSLM), a model previously published in the statistics literature, is shown to have coefficients that correspond to the intensive partial molar properties. If a measured property is plotted against the mole fraction of a component while keeping the proportions of all other components constant, the slope at any given point on a graph of this curve is the partial molar property for that constituent. Actually plotting this graph has been used to determine partial molar properties for many years. The CSLM directly includes this slope in a model that predicts properties as a function of the component mole fractions. This model is demonstrated by applying it to the constant pressure heat capacity data from the NaOH-NaAl(OH{sub 4}H{sub 2}O system, a system that simplifies Hanford nuclear waste. The partial molar properties of H{sub 2}O, NaOH, and NaAl(OH){sub 4} are determined. The equivalence of the CSLM and the graphical method is verified by comparing results detennined by the two methods. The CSLM model has been previously used to predict the liquidus temperature of spinel crystals precipitated from Hanford waste glass. Those model coefficients are re-interpreted here as the partial molar spinel liquidus temperature of the glass components.

  5. Refinement and verification in component-based model-driven design

    DEFF Research Database (Denmark)

    Chen, Zhenbang; Liu, Zhiming; Ravn, Anders Peter

    2009-01-01

    Modern software development is complex as it has to deal with many different and yet related aspects of applications. In practical software engineering this is now handled by a UML-like modelling approach in which different aspects are modelled by different notations. Component-based and object...... of Refinement of Component and Object Systems (rCOS) and illustrates it with experiences from the work on the Common Component Modelling Example (CoCoME). This gives evidence that the formal techniques developed in rCOS can be integrated into a model-driven development process and shows where it may...

  6. The component model of infrastructure: a practical approach to understanding public health program infrastructure.

    Science.gov (United States)

    Lavinghouze, S René; Snyder, Kimberly; Rieker, Patricia P

    2014-08-01

    Functioning program infrastructure is necessary for achieving public health outcomes. It is what supports program capacity, implementation, and sustainability. The public health program infrastructure model presented in this article is grounded in data from a broader evaluation of 18 state tobacco control programs and previous work. The newly developed Component Model of Infrastructure (CMI) addresses the limitations of a previous model and contains 5 core components (multilevel leadership, managed resources, engaged data, responsive plans and planning, networked partnerships) and 3 supporting components (strategic understanding, operations, contextual influences). The CMI is a practical, implementation-focused model applicable across public health programs, enabling linkages to capacity, sustainability, and outcome measurement.

  7. Hybrid time/frequency domain modeling of nonlinear components

    DEFF Research Database (Denmark)

    Wiechowski, Wojciech Tomasz; Lykkegaard, Jan; Bak, Claus Leth

    2007-01-01

    model is used as a basis for its implementation. First, the linear network part is replaced with an ideal voltage source and a time domain (EMT) simulation is performed. During the initial oscillations, harmonic content of the converter currents is calculated at every period by a fast Fourier transform...... and the periodic steady state is identified. Obtained harmonic currents are assigned to current sources and used in the frequency domain calculation in the linear network. The obtained three-phase bus voltage is then inverse Fourier transformed and assigned to the voltage source and the time domain simulation...... is performed again. This process is repeated until the change in the magnitudes and phase angles of the fundamental and low order characteristic harmonics of the bus voltage is smaller then predefined precision indexes. The method is verified against precise time domain simulation. The convergence properties...

  8. Symmetric multi-component diffusion modeling for Magnum PSI

    Science.gov (United States)

    Peerenboom, Kim; van Dijk, Jan; Goedheer, Wim; van der Mullen, Joost

    2011-10-01

    Magnum PSI is a linear plasma generator for studying plasma surface interaction in conditions as expected in the ITER divertor. In Magnum PSI, the diffusive fluxes do not follow the simple Fick law for diffusion, due to coupling of the fluxes between species and directions, and ambipolar and magnetic fields. Instead they are described by the Stefan-Maxwell equations. In our contribution, we will address the numerical issues associated with solving the Stefan-Maxwell equations and the resulting set of continuity equations for the species. In particular, we will present a symmetric approach where all species are treated as independent unknowns and no species are singled out in order to account for mass and charge conservation. Modeling results of Magnum PSI using this approach will be presented.

  9. Performance measurement and modeling of component applications in a high performance computing environment : a case study.

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Robert C.; Ray, Jaideep; Malony, A. (University of Oregon, Eugene, OR); Shende, Sameer (University of Oregon, Eugene, OR); Trebon, Nicholas D.

    2003-11-01

    We present a case study of performance measurement and modeling of a CCA (Common Component Architecture) component-based application in a high performance computing environment. We explore issues peculiar to component-based HPC applications and propose a performance measurement infrastructure for HPC based loosely on recent work done for Grid environments. A prototypical implementation of the infrastructure is used to collect data for a three components in a scientific application and construct performance models for two of them. Both computational and message-passing performance are addressed.

  10. Coordinated Cluster, ground-based instrumentation and low-altitude satellite observations of transient poleward-moving events in the ionosphere and in the tail lobe

    Directory of Open Access Journals (Sweden)

    M. Lockwood

    Full Text Available During the interval between 8:00–9:30 on 14 January 2001, the four Cluster spacecraft were moving from the central magnetospheric lobe, through the dusk sector mantle, on their way towards intersecting the magnetopause near 15:00 MLT and 15:00 UT. Throughout this interval, the EISCAT Svalbard Radar (ESR at Longyearbyen observed a series of poleward-moving transient events of enhanced F-region plasma concentration ("polar cap patches", with a repetition period of the order of 10 min. Allowing for the estimated solar wind propagation delay of 75 ( ± 5 min, the interplanetary magnetic field (IMF had a southward component during most of the interval. The magnetic footprint of the Cluster spacecraft, mapped to the ionosphere using the Tsyganenko T96 model (with input conditions prevailing during this event, was to the east of the ESR beams. Around 09:05 UT, the DMSP-F12 satellite flew over the ESR and showed a sawtooth cusp ion dispersion signature that also extended into the electrons on the equatorward edge of the cusp, revealing a pulsed magnetopause reconnection. The consequent enhanced ionospheric flow events were imaged by the SuperDARN HF backscatter radars. The average convection patterns (derived using the AMIE technique on data from the magnetometers, the EISCAT and SuperDARN radars, and the DMSP satellites show that the associated poleward-moving events also convected over the predicted footprint of the Cluster spacecraft. Cluster observed enhancements in the fluxes of both electrons and ions. These events were found to be essentially identical at all four spacecraft, indicating that they had a much larger spatial scale than the satellite separation of the order of 600 km. Some of the events show a correspondence between the lowest energy magnetosheath electrons detected by the PEACE instrument on Cluster (10–20 eV and the topside ionospheric enhancements seen by the ESR (at 400–700 km. We suggest that a potential barrier at the

  11. Variable-lattice model of multi-component systems. 1. General consideration

    OpenAIRE

    Zakharov, A. Yu.; Schneider, A. A.; Udovsky, A. L.

    2010-01-01

    The paper contains a development of the previously proposed generalized lattice model (GLM). In contrast to usual lattice models, the difference of the specific atomic volumes of the components is taken in account in GLM. In addition to GLM, the dependence of the specific atomic volumes on local atomic environments taken into account in new variable-lattice model (VLM). Thermodynamic functions of multi-component homogeneous phases in the VLM are obtained. Equations of equilibrium between gase...

  12. A Dynamic Multinode Model for Component-Oriented Thermal Analysis of Flat-Plate Solar Collectors

    OpenAIRE

    Reiter, Christoph N.; Christoph Trinkl; Wilfried Zörner; Hanby, Vic I.

    2015-01-01

    A mathematical model of a flat-plate solar collector was developed on the basis of the physical principles of optics and heat transfer in order to determine collector’s component temperatures as well as collector efficiency. In contrast to many available models, the targeted use of this dynamic model is the detailed, theoretical investigation of the thermal behaviour of newly developed or adjusted collector designs on component level, for example, absorber, casing, or transparent cover. The d...

  13. A Component-Based Debugging Approach for Detecting Structural Inconsistencies in Declarative Equation Based Models

    Institute of Scientific and Technical Information of China (English)

    Jian-Wan Ding; Li-Ping Chen; Fan-Li Zhou

    2006-01-01

    Object-oriented modeling with declarative equation based languages often unconsciously leads to structural inconsistencies. Component-based debugging is a new structural analysis approach that addresses this problem by analyzing the structure of each component in a model to separately locate faulty components. The analysis procedure is performed recursively based on the depth-first rule. It first generates fictitious equations for a component to establish a debugging environment, and then detects structural defects by using graph theoretical approaches to analyzing the structure of the system of equations resulting from the component. The proposed method can automatically locate components that cause the structural inconsistencies, and show the user detailed error messages. This information can be a great help in finding and localizing structural inconsistencies, and in some cases pinpoints them immediately.

  14. PRINCIPAL COMPONENT DECOMPOSITION BASED FINITE ELEMENT MODEL UPDATING FOR STRAIN-RATE-DEPENDENCE NONLINEAR DYNAMIC PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    GUO Qintao; ZHANG Lingmi; TAO Zheng

    2008-01-01

    Thin wall component is utilized to absorb impact energy of a structure. However, the dynamic behavior of such thin-walled structure is highly non-linear with material, geometry and boundary non-linearity. A model updating and validation procedure is proposed to build accurate finite element model of a frame structure with a non-linear thin-walled component for dynamic analysis. Design of experiments (DOE) and principal component decomposition (PCD) approach are applied to extract dynamic feature from nonlinear impact response for correlation of impact test result and FE model of the non-linear structure. A strain-rate-dependent non-linear model updating method is then developed to build accurate FE model of the structure. Computer simulation and a real frame structure with a highly non-linear thin-walled component are employed to demonstrate the feasibility and effectiveness of the proposed approach.

  15. Conceptual model of iCAL4LA: Proposing the components using comparative analysis

    Science.gov (United States)

    Ahmad, Siti Zulaiha; Mutalib, Ariffin Abdul

    2016-08-01

    This paper discusses an on-going study that initiates an initial process in determining the common components for a conceptual model of interactive computer-assisted learning that is specifically designed for low achieving children. This group of children needs a specific learning support that can be used as an alternative learning material in their learning environment. In order to develop the conceptual model, this study extracts the common components from 15 strongly justified computer assisted learning studies. A comparative analysis has been conducted to determine the most appropriate components by using a set of specific indication classification to prioritize the applicability. The results of the extraction process reveal 17 common components for consideration. Later, based on scientific justifications, 16 of them were selected as the proposed components for the model.

  16. Hadronic Models for the Extra Spectral Component in the short GRB 090510

    CERN Document Server

    Asano, Katsuaki; Mészáros, Peter

    2009-01-01

    A short gamma-ray burst GRB 090510 detected by {\\it Fermi} shows an extra spectral component between 10 MeV and 30 GeV, an addition to a more usual low-energy ($<10$ MeV) Band component. In general, such an extra component could originate from accelerated protons. In particular, inverse Compton emission from secondary electron-positron pairs and proton synchrotron emission are competitive models for reproducing the hard spectrum of the extra component in GRB 090510. Here, using Monte Carlo simulations, we test the hadronic scenarios against the observed properties. To reproduce the extra component around GeV with these models, the proton injection isotropic-equivalent luminosity is required to be larger than $10^{55}$ erg$ / $s. Such large proton luminosities are a challenge for the hadronic models.

  17. A mathematical model for the dissolution of stoichiometric particles in multi-component alloys

    NARCIS (Netherlands)

    Vermolen, F.J.; Vuik, C.; Van der Zwaag, S.

    2001-01-01

    A general model for the dissolution of stoichiometric particles in multi-component alloys is proposed and analysed. We introduce the concept of mass-conserving solutions and give a self-similar solution for the resulting Stefan-problem. Furthermore, we show that particle dissolution in multi-compone

  18. Analyzing perturbation characteristic and orbital maintenance strategy for super low altitude satellite%超低轨道卫星摄动特性分析及轨道维持方法

    Institute of Scientific and Technical Information of China (English)

    温生林; 闫野; 易腾

    2015-01-01

    针对超低轨道卫星长时间在轨飞行的轨道维持问题,分析了超低轨道平均偏心率矢量变化特性,提出了一种超低轨道维持的控制方法。分析了 J2、J3摄动以及大气阻力摄动作用下超低轨道卫星偏心率矢量的变化特性;基于能量守恒原理设计了超低轨道高度维持的控制策略;通过仿真算例验证了控制策略的有效性。结果表明:在地球非球形引力摄动、大气阻力摄动和速度脉冲作用下超低轨道平均偏心率的变化是稳定的,所设计的轨道维持方法不仅能够实现超低轨道高度维持,确保平均偏心率矢量收敛至平衡位置,且用于轨道维持的燃料消耗合理,能够满足长时间的超低轨道飞行要求。%Aiming at the orbital maintenance problem of super low altitude satellite for the long duration of the flight,the variation characteristics of the average eccentricity vector were analyzed and an orbital maintenance method was presented.Firstly,the change of average eccentricity vector characteristic of super low altitude satellite under the J2 ,J3 zonal terms and the atmospheric drag was analyzed.Then an orbital maintenance strategy based on energy conservation principle was proposed.Finally,the effectiveness of orbital maintenance strategy was validated by simulation examples.Simulation results show that the changes of average eccentricity is stable under the perturbation of the earth non-spherical gravity,the atmospheric drag and the impulsive maneuver,and the proposed orbital maintenance method can effectively achieve super low altitude maintenance and make the average eccentricity vector converge to equilibrium point.Besides,the fuel consumption for orbital maintenance is reasonable and the long duration flight in super low orbit can be achieved.

  19. Model-Based Design Tools for Extending COTS Components To Extreme Environments Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation in this project is model-based design (MBD) tools for predicting the performance and useful life of commercial-off-the-shelf (COTS) components and...

  20. Conservative modelling of the moisture and heat transfer in building components under atmospheric excitation

    DEFF Research Database (Denmark)

    Janssen, Hans; Blocken, Bert; Carmeliet, Jan

    2007-01-01

    While the transfer equations for moisture and heat in building components are currently undergoing standardisation, atmospheric boundary conditions, conservative modelling and numerical efficiency are not addressed. In a first part, this paper adds a comprehensive description of those boundary co...

  1. Detailed finite element method modeling of evaporating multi-component droplets

    Energy Technology Data Exchange (ETDEWEB)

    Diddens, Christian, E-mail: C.Diddens@tue.nl

    2017-07-01

    The evaporation of sessile multi-component droplets is modeled with an axisymmetic finite element method. The model comprises the coupled processes of mixture evaporation, multi-component flow with composition-dependent fluid properties and thermal effects. Based on representative examples of water–glycerol and water–ethanol droplets, regular and chaotic examples of solutal Marangoni flows are discussed. Furthermore, the relevance of the substrate thickness for the evaporative cooling of volatile binary mixture droplets is pointed out. It is shown how the evaporation of the more volatile component can drastically decrease the interface temperature, so that ambient vapor of the less volatile component condenses on the droplet. Finally, results of this model are compared with corresponding results of a lubrication theory model, showing that the application of lubrication theory can cause considerable errors even for moderate contact angles of 40°. - Graphical abstract:.

  2. A proposed centralised distribution model for the South African automotive component industry

    Directory of Open Access Journals (Sweden)

    Micheline J. Naude

    2009-12-01

    Full Text Available Purpose: This article explores the possibility of developing a distribution model, similar to the model developed and implemented by the South African pharmaceutical industry, which could be implemented by automotive component manufacturers for supply to independent retailers. Problem Investigated: The South African automotive components distribution chain is extensive with a number of players of varying sizes, from the larger spares distribution groups to a number of independent retailers. Distributing to the smaller independent retailers is costly for the automotive component manufacturers. Methodology: This study is based on a preliminary study of an explorative nature. Interviews were conducted with a senior staff member from a leading automotive component manufacturer in KwaZulu Natal and nine participants at a senior management level at five of their main customers (aftermarket retailers. Findings: The findings from the empirical study suggest that the aftermarket component industry is mature with the role players well established. The distribution chain to the independent retailer is expensive in terms of transaction and distribution costs for the automotive component manufacturer. A proposed centralised distribution model for supply to independent retailers has been developed which should reduce distribution costs for the automotive component manufacturer in terms of (1 the lowest possible freight rate; (2 timely and controlled delivery; and (3 reduced congestion at the customer's receiving dock. Originality: This research is original in that it explores the possibility of implementing a centralised distribution model for independent retailers in the automotive component industry. Furthermore, there is a dearth of published research on the South African automotive component industry particularly addressing distribution issues. Conclusion: The distribution model as suggested is a practical one and should deliver added value to automotive

  3. Analytical model for removal of a uniformly distributed single-component NAPL under nonequilibrium conditions

    NARCIS (Netherlands)

    Brouwers, Jos; Augustijn, Dionysius C.M.

    2001-01-01

    In this paper a simple analytical model is presented for the one-dimensional transport equation describing the removal of a uniformly distributed, single-component NAPL under nonequilibrium conditions. Both advective and dispersive transport are included in the model. The model describes two

  4. Quantifying functional connectivity in multi-subject fMRI data using component models

    DEFF Research Database (Denmark)

    Madsen, Kristoffer Hougaard; Churchill, Nathan William; Mørup, Morten

    2017-01-01

    -generalizing models account for subject variability within a common spatial subspace. Within this set of models, spatial Independent Component Analysis (sICA) on concatenated data provides more interpretable brain patterns, whereas a consistent-covariance model that accounts for subject-specific network scaling...

  5. Incorporating hysteresis in a multi-phase multi-component NAPL modelling framework; a multi-component LNAPL gasoline example

    Science.gov (United States)

    Sookhak Lari, Kaveh; Davis, Greg B.; Johnston, Colin D.

    2016-10-01

    The longevity of chemicals in subsurface NAPL releases is a function of their partitioning into different phases. Hysteresis can affect distribution and partitioning of compounds in the vadose zone. We separated and modified hysteresis code from NAPL Simulator (which include hysteresis caused by fluid entrapment and capillary effects) and embedded it into TMVOC. For the first time, the resulting framework is used to model multi-component and multi-phase NAPL release, partitioning and transport. We then applied the verified framework to model effects of hysteresis on partitioning of BTEX, TMB and short and long chain alkanes from a typical gasoline spill. Excluding hysteresis resulted in an expanded LNAPL plume and underestimated the compounds longevity. Hysteresis altered the spatial distribution of LNAPL molar fractions as well as gas flow path and contaminants distribution compared to the non-hysteretic case. The amplifying effect of hysteresis on the longevity of mixtures (and associated risks) should be considered if non-hysteretic relationships are applied.

  6. Automatic Detection of Repetitive Components in 3D Mechanical Engineering Models

    Directory of Open Access Journals (Sweden)

    Laixiang Wen

    2013-01-01

    Full Text Available We present an intelligent method to automatically detect repetitive components in 3D mechanical engineering models. In our work, a new Voxel-based Shape Descriptor (VSD is proposed for effective matching, based on which a similarity function is defined. It uses the voxels intersecting with 3D outline of mechanical components as the feature descriptor. Because each mechanical component may have different poses, the alignment before the matching is needed. For the alignment, we adopt the genetic algorithm to search for optimal solution where the maximum global similarity is the objective. Two components are the same if the maximum global similarity is over a certain threshold. Note that the voxelization of component during feature extraction and the genetic algorithm for searching maximum global similarity are entirely implemented on GPU; the efficiency is improved significantly than with CPU. Experimental results show that our method is more effective and efficient than that existing methods for repetitive components detection.

  7. 构件质量模型研究%Research on component quality model

    Institute of Scientific and Technical Information of China (English)

    杜云; 姜瑛

    2011-01-01

    基于ISO/IEC 9126软件质量标准,结合白盒构件和黑盒构件的特点,提出了适用于构件开发者、复用者和第3方的构件质量模型,为构件评价工作提供一定的参考.%This paper proposes a component quality model based on ISO/IEC 9126 standard,which combines the features of black box and white box component.The component quality model aims at component developer, reuser and the third party.It can provide feasible reference for component evaluation.

  8. Identifying common components across biological network graphs using a bipartite data model.

    Science.gov (United States)

    Baker, Ej; Culpepper, C; Philips, C; Bubier, J; Langston, M; Chesler, Ej

    2014-01-01

    The GeneWeaver bipartite data model provides an efficient means to evaluate shared molecular components from sets derived across diverse species, disease states and biological processes. In order to adapt this model for examining related molecular components and biological networks, such as pathway or gene network data, we have developed a means to leverage the bipartite data structure to extract and analyze shared edges. Using the Pathway Commons database we demonstrate the ability to rapidly identify shared connected components among a diverse set of pathways. In addition, we illustrate how results from maximal bipartite discovery can be decomposed into hierarchical relationships, allowing shared pathway components to be mapped through various parent-child relationships to help visualization and discovery of emergent kernel driven relationships. Interrogating common relationships among biological networks and conventional GeneWeaver gene lists will increase functional specificity and reliability of the shared biological components. This approach enables self-organization of biological processes through shared biological networks.

  9. Enhanced hepatic insulin signaling in the livers of high altitude native rats under basal conditions and in the livers of low altitude native rats under insulin stimulation: a mechanistic study.

    Science.gov (United States)

    Al Dera, Hussain; Eleawa, Samy M; Al-Hashem, Fahaid H; Mahzari, Moeber M; Hoja, Ibrahim; Al Khateeb, Mahmoud

    2017-07-01

    This study was designed to investigate the role of the liver in lowering fasting blood glucose levels (FBG) in rats native to high (HA) and low altitude (LA) areas. As compared with LA natives, besides the improved insulin and glucose tolerance, HA native rats had lower FBG, at least mediated by inhibition of hepatic gluconeogenesis and activation of glycogen synthesis. An effect that is mediated by the enhancement of hepatic insulin signaling mediated by the decreased phosphorylation of TSC induced inhibition of mTOR function. Such effect was independent of activation of AMPK nor stabilization of HIF1α, but most probably due to oxidative stress induced REDD1 expression. However, under insulin stimulation, and in spite of the less activated mTOR function in HA native rats, LA native rats had higher glycogen content and reduced levels of gluconeogenic enzymes with a more enhanced insulin signaling, mainly due to higher levels of p-IRS1 (tyr612).

  10. Model Components of the Certification Framework for Geologic Carbon Sequestration Risk Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Oldenburg, Curtis M.; Bryant, Steven L.; Nicot, Jean-Philippe; Kumar, Navanit; Zhang, Yingqi; Jordan, Preston; Pan, Lehua; Granvold, Patrick; Chow, Fotini K.

    2009-06-01

    We have developed a framework for assessing the leakage risk of geologic carbon sequestration sites. This framework, known as the Certification Framework (CF), emphasizes wells and faults as the primary potential leakage conduits. Vulnerable resources are grouped into compartments, and impacts due to leakage are quantified by the leakage flux or concentrations that could potentially occur in compartments under various scenarios. The CF utilizes several model components to simulate leakage scenarios. One model component is a catalog of results of reservoir simulations that can be queried to estimate plume travel distances and times, rather than requiring CF users to run new reservoir simulations for each case. Other model components developed for the CF and described here include fault characterization using fault-population statistics; fault connection probability using fuzzy rules; well-flow modeling with a drift-flux model implemented in TOUGH2; and atmospheric dense-gas dispersion using a mesoscale weather prediction code.

  11. Raw Data Maximum Likelihood Estimation for Common Principal Component Models: A State Space Approach.

    Science.gov (United States)

    Gu, Fei; Wu, Hao

    2016-09-01

    The specifications of state space model for some principal component-related models are described, including the independent-group common principal component (CPC) model, the dependent-group CPC model, and principal component-based multivariate analysis of variance. Some derivations are provided to show the equivalence of the state space approach and the existing Wishart-likelihood approach. For each model, a numeric example is used to illustrate the state space approach. In addition, a simulation study is conducted to evaluate the standard error estimates under the normality and nonnormality conditions. In order to cope with the nonnormality conditions, the robust standard errors are also computed. Finally, other possible applications of the state space approach are discussed at the end.

  12. Penalising Model Component Complexity: A Principled, Practical Approach to Constructing Priors

    KAUST Repository

    Simpson, Daniel

    2017-04-06

    In this paper, we introduce a new concept for constructing prior distributions. We exploit the natural nested structure inherent to many model components, which defines the model component to be a flexible extension of a base model. Proper priors are defined to penalise the complexity induced by deviating from the simpler base model and are formulated after the input of a user-defined scaling parameter for that model component, both in the univariate and the multivariate case. These priors are invariant to repa-rameterisations, have a natural connection to Jeffreys\\' priors, are designed to support Occam\\'s razor and seem to have excellent robustness properties, all which are highly desirable and allow us to use this approach to define default prior distributions. Through examples and theoretical results, we demonstrate the appropriateness of this approach and how it can be applied in various situations.

  13. Mixture experiment techniques for reducing the number of components applied for modeling waste glass sodium release

    Energy Technology Data Exchange (ETDEWEB)

    Piepel, G.; Redgate, T. [Pacific Northwest National Lab., Richland, WA (United States). Statistics Group

    1997-12-01

    Statistical mixture experiment techniques were applied to a waste glass data set to investigate the effects of the glass components on Product Consistency Test (PCT) sodium release (NR) and to develop a model for PCT NR as a function of the component proportions. The mixture experiment techniques indicate that the waste glass system can be reduced from nine to four components for purposes of modeling PCT NR. Empirical mixture models containing four first-order terms and one or two second-order terms fit the data quite well, and can be used to predict the NR of any glass composition in the model domain. The mixture experiment techniques produce a better model in less time than required by another approach.

  14. The two-component model of memory development, and its potential implications for educational settings.

    Science.gov (United States)

    Sander, Myriam C; Werkle-Bergner, Markus; Gerjets, Peter; Shing, Yee Lee; Lindenberger, Ulman

    2012-02-15

    We recently introduced a two-component model of the mechanisms underlying age differences in memory functioning across the lifespan. According to this model, memory performance is based on associative and strategic components. The associative component is relatively mature by middle childhood, whereas the strategic component shows a maturational lag and continues to develop until young adulthood. Focusing on work from our own lab, we review studies from the domains of episodic and working memory informed by this model, and discuss their potential implications for educational settings. The episodic memory studies uncover the latent potential of the associative component in childhood by documenting children's ability to greatly improve their memory performance following mnemonic instruction and training. The studies on working memory also point to an immature strategic component in children whose operation is enhanced under supportive conditions. Educational settings may aim at fostering the interplay between associative and strategic components. We explore possible routes towards this goal by linking our findings to recent trends in research on instructional design. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. A component modes projection and assembly model reduction methodology for articulated, multi-flexible body structures

    Science.gov (United States)

    Lee, Allan Y.; Tsuha, Walter S.

    1993-01-01

    A two-stage model reduction methodology, combining the classical Component Mode Synthesis (CMS) method and the newly developed Enhanced Projection and Assembly (EP&A) method, is proposed in this research. The first stage of this methodology, called the COmponent Modes Projection and Assembly model REduction (COMPARE) method, involves the generation of CMS mode sets, such as the MacNeal-Rubin mode sets. These mode sets are then used to reduce the order of each component model in the Rayleigh-Ritz sense. The resultant component models are then combined to generate reduced-order system models at various system configurations. A composite mode set which retains important system modes at all system configurations is then selected from these reduced-order system models. In the second stage, the EP&A model reduction method is employed to reduce further the order of the system model generated in the first stage. The effectiveness of the COMPARE methodology has been successfully demonstrated on a high-order, finite-element model of the cruise-configured Galileo spacecraft.

  16. A novel prediction method about single components of analog circuits based on complex field modeling.

    Science.gov (United States)

    Zhou, Jingyu; Tian, Shulin; Yang, Chenglin

    2014-01-01

    Few researches pay attention to prediction about analog circuits. The few methods lack the correlation with circuit analysis during extracting and calculating features so that FI (fault indicator) calculation often lack rationality, thus affecting prognostic performance. To solve the above problem, this paper proposes a novel prediction method about single components of analog circuits based on complex field modeling. Aiming at the feature that faults of single components hold the largest number in analog circuits, the method starts with circuit structure, analyzes transfer function of circuits, and implements complex field modeling. Then, by an established parameter scanning model related to complex field, it analyzes the relationship between parameter variation and degeneration of single components in the model in order to obtain a more reasonable FI feature set via calculation. According to the obtained FI feature set, it establishes a novel model about degeneration trend of analog circuits' single components. At last, it uses particle filter (PF) to update parameters for the model and predicts remaining useful performance (RUP) of analog circuits' single components. Since calculation about the FI feature set is more reasonable, accuracy of prediction is improved to some extent. Finally, the foregoing conclusions are verified by experiments.

  17. A Novel Prediction Method about Single Components of Analog Circuits Based on Complex Field Modeling

    Directory of Open Access Journals (Sweden)

    Jingyu Zhou

    2014-01-01

    Full Text Available Few researches pay attention to prediction about analog circuits. The few methods lack the correlation with circuit analysis during extracting and calculating features so that FI (fault indicator calculation often lack rationality, thus affecting prognostic performance. To solve the above problem, this paper proposes a novel prediction method about single components of analog circuits based on complex field modeling. Aiming at the feature that faults of single components hold the largest number in analog circuits, the method starts with circuit structure, analyzes transfer function of circuits, and implements complex field modeling. Then, by an established parameter scanning model related to complex field, it analyzes the relationship between parameter variation and degeneration of single components in the model in order to obtain a more reasonable FI feature set via calculation. According to the obtained FI feature set, it establishes a novel model about degeneration trend of analog circuits’ single components. At last, it uses particle filter (PF to update parameters for the model and predicts remaining useful performance (RUP of analog circuits’ single components. Since calculation about the FI feature set is more reasonable, accuracy of prediction is improved to some extent. Finally, the foregoing conclusions are verified by experiments.

  18. Review of modeling and control during transport airdrop process

    Directory of Open Access Journals (Sweden)

    Bin Xu

    2016-12-01

    Full Text Available This article presents the review of modeling and control during the airdrop process of transport aircraft. According to the airdrop height, technology can be classified into high and low altitude airdrop and in this article, the research is reviewed based on the two scenarios. While high altitude airdrop is mainly focusing on the precise landing control of cargo, the low altitude flight airdrop is on the control of transport aircraft dynamics to ensure flight safety. The history of high precision airdrop system is introduced first, and then the modeling and control problem of the ultra low altitude airdrop in transport aircraft is presented. Finally, the potential problems and future direction of low altitude airdrop are discussed.

  19. A comparative study of the proposed models for the components of the national health information system.

    Science.gov (United States)

    Ahmadi, Maryam; Damanabi, Shahla; Sadoughi, Farahnaz

    2014-04-01

    National Health Information System plays an important role in ensuring timely and reliable access to Health information, which is essential for strategic and operational decisions that improve health, quality and effectiveness of health care. In other words, using the National Health information system you can improve the quality of health data, information and knowledge used to support decision making at all levels and areas of the health sector. Since full identification of the components of this system - for better planning and management influential factors of performanceseems necessary, therefore, in this study different attitudes towards components of this system are explored comparatively. This is a descriptive and comparative kind of study. The society includes printed and electronic documents containing components of the national health information system in three parts: input, process and output. In this context, search for information using library resources and internet search were conducted, and data analysis was expressed using comparative tables and qualitative data. The findings showed that there are three different perspectives presenting the components of national health information system Lippeveld and Sauerborn and Bodart model in 2000, Health Metrics Network (HMN) model from World Health Organization in 2008, and Gattini's 2009 model. All three models outlined above in the input (resources and structure) require components of management and leadership, planning and design programs, supply of staff, software and hardware facilities and equipment. Plus, in the "process" section from three models, we pointed up the actions ensuring the quality of health information system, and in output section, except for Lippeveld Model, two other models consider information products and use and distribution of information as components of the national health information system. the results showed that all the three models have had a brief discussion about the

  20. Using Principal Component Analysis And Choqet Integral To Establish A Diagnostic Model of Parkinson Disease

    Science.gov (United States)

    cao, Xiuming; Song, Jinjie; Zhang, Caipo

    This work focused on principal component analysis and Choquet integral to structure a model of diagnose Parkinson disease. The proper value of Sugeno measure is vital to a diagnostic model. This paper aims at providing a method of using principal component analysis to obtain the sugeno measure. In this diagnostic model, there are two key elements. One is the goodness of fit that the degrees of evidential support for attribute. The other is the importance of attribute itself. The instances of Parkinson disease illuminate that the method is effective.

  1. Computer models of steam pipeline components in the evaluation of their local strength

    OpenAIRE

    J. Okrajni; W. Essler

    2010-01-01

    Purpose: The paper discusses the issue of modelling the heating and cooling processes of T-pipes in a power plant pipeline in the start-up conditions of a boiler. The main purpose of this work is the description of the mechanical behaviour of power plant components working under mechanical and thermal loading and validation of the computer modelling methods.Design/methodology/approach: The FEM modelling has been used to describe the local stress-strain behaviour of the chosen component.Findin...

  2. A discrimination-association model for decomposing component processes of the implicit association test.

    Science.gov (United States)

    Stefanutti, Luca; Robusto, Egidio; Vianello, Michelangelo; Anselmi, Pasquale

    2013-06-01

    A formal model is proposed that decomposes the implicit association test (IAT) effect into three process components: stimuli discrimination, automatic association, and termination criterion. Both response accuracy and reaction time are considered. Four independent and parallel Poisson processes, one for each of the four label categories of the IAT, are assumed. The model parameters are the rate at which information accrues on the counter of each process and the amount of information that is needed before a response is given. The aim of this study is to present the model and an illustrative application in which the process components of a Coca-Pepsi IAT are decomposed.

  3. Modeling and prediction of children’s growth data via functional principal component analysis

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We use the functional principal component analysis(FPCA) to model and predict the weight growth in children.In particular,we examine how the approach can help discern growth patterns of underweight children relative to their normal counterparts,and whether a commonly used transformation to normality plays any constructive roles in a predictive model based on the FPCA.Our work supplements the conditional growth charts developed by Wei and He(2006) by constructing a predictive growth model based on a small number of principal components scores on individual’s past.

  4. Abstract behavior types : a foundation model for components and their composition

    NARCIS (Netherlands)

    Arbab, F.

    2003-01-01

    The notion of Abstract Data Type (ADT) has served as a foundation model for structured and object oriented programming for some thirty years. The current trend in software engineering toward component based systems requires a foundation model as well. The most basic inherent property of an ADT, i.e.

  5. A Personality Dynamics Model for the Self-Evaluation Component of Personal and Professional Development.

    Science.gov (United States)

    Miller, Edith A.; Pascoe, Donna E.

    An evaluation model was designed to be a self-evaluation component to be used in conceptualizing and implementing personal and professional development plans. The personality dynamics model itself, beyond its theoretical bases, includes the following techniques to assist the individual in the self-evaluation process leading to plan development:…

  6. Instabilities on crystal surfaces: The two-component body-centered solid-on-solid model

    NARCIS (Netherlands)

    Carlon, E.; van Beijeren, H.; Mazzeo, G.

    1996-01-01

    The free energy of crystal surfaces that can be described by the two-component body-centered solid-on-solid model has been calculated in a mean-field approximation. The system may model ionic crystals with a bcc lattice structure (for instance CsCl). Crossings between steps are energetically favored

  7. Analytical modeling of multi-layered Printed Circuit Board dedicated to electronic component thermal characterization

    Science.gov (United States)

    Monier-Vinard, Eric; Laraqi, Najib; Dia, Cheikh-Tidiane; Nguyen, Minh-Nhat; Bissuel, Valentin

    2015-01-01

    Electronic components are continuously getting smaller and embedding more and more powered functions which exacerbate the temperature rise in component/board interconnect areas. For still air conditions, the heat spreading of the component power is mainly done through the surrounding metallic planes of its electronic board. Their design optimization is henceforth mandatory to control the temperature and to preserve component reliability. To allow the electronic designer to early analyze the limits of the power dissipation of miniaturized devices, an analytical model of a multi-layered electronic board was established with the purpose to assess the validity of conventional board modeling approach. For decades, numerous authors have been promoting a homogenous single layer model that summed up the layers of the board using effective orthotropic thermal properties. The derived compact model depends on thermal properties approximation which is commonly based on parallel conduction model given a linear rule of mixture. The work presents the thermal behavior comparison of a detailed multi-layer representation to its deducted compact model for an extensive set of variable parameters, such as heat transfer coefficients, effective thermal conductivities calculation models, number of trace layers, trace coverage or source size. The results highlight the fact that the conventional practices for PCB modeling can dramatically underestimate source temperatures when their size is getting very small.

  8. A Co-modeling Method Based on Component Features for Mechatronic Devices in Aero-engines

    Science.gov (United States)

    Wang, Bin; Zhao, Haocen; Ye, Zhifeng

    2017-08-01

    Data-fused and user-friendly design of aero-engine accessories is required because of their structural complexity and stringent reliability. This paper gives an overview of a typical aero-engine control system and the development process of key mechatronic devices used. Several essential aspects of modeling and simulation in the process are investigated. Considering the limitations of a single theoretic model, feature-based co-modeling methodology is suggested to satisfy the design requirements and compensate for diversity of component sub-models for these devices. As an example, a stepper motor controlled Fuel Metering Unit (FMU) is modeled in view of the component physical features using two different software tools. An interface is suggested to integrate the single discipline models into the synthesized one. Performance simulation of this device using the co-model and parameter optimization for its key components are discussed. Comparison between delivery testing and the simulation shows that the co-model for the FMU has a high accuracy and the absolute superiority over a single model. Together with its compatible interface with the engine mathematical model, the feature-based co-modeling methodology is proven to be an effective technical measure in the development process of the device.

  9. Kinetic Modeling of Gasoline Surrogate Components and Mixtures under Engine Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mehl, M; Pitz, W J; Westbrook, C K; Curran, H J

    2010-01-11

    Real fuels are complex mixtures of thousands of hydrocarbon compounds including linear and branched paraffins, naphthenes, olefins and aromatics. It is generally agreed that their behavior can be effectively reproduced by simpler fuel surrogates containing a limited number of components. In this work, an improved version of the kinetic model by the authors is used to analyze the combustion behavior of several components relevant to gasoline surrogate formulation. Particular attention is devoted to linear and branched saturated hydrocarbons (PRF mixtures), olefins (1-hexene) and aromatics (toluene). Model predictions for pure components, binary mixtures and multicomponent gasoline surrogates are compared with recent experimental information collected in rapid compression machine, shock tube and jet stirred reactors covering a wide range of conditions pertinent to internal combustion engines (3-50 atm, 650-1200K, stoichiometric fuel/air mixtures). Simulation results are discussed focusing attention on the mixing effects of the fuel components.

  10. Development of pure component property models for chemical product-process design and analysis

    DEFF Research Database (Denmark)

    Hukkerikar, Amol Shivajirao

    Property prediction models based on the group-contribution+ (GC+) approach have been developed to provide reliable predictions of pure component properties together with uncertainties of predicted property values which is much needed information in performing chemical product and process design...... the CAPEC database, the US Environmental Protection Agency (EPA) database, and the USEtox database are used. In total, 21 thermo-physical properties and 22 environmental-related properties of pure components which include normal boiling point, critical constants, standard enthalpy of formation, liquid...... be applied to a wide range of properties of pure components. pure components. In this work, however, the application of ‘molecular structural similarity criteria’ is illustrated by considering performance improvement of models for enthalpy of formation, enthalpy of fusion, and critical temperature. For all...

  11. Modeling Thermal Dust Emission with Two Components: Application to the Planck High Frequency Instrument Maps

    Science.gov (United States)

    Meisner, Aaron M.; Finkbeiner, Douglas P.

    2015-01-01

    We apply the Finkbeiner et al. two-component thermal dust emission model to the Planck High Frequency Instrument maps. This parameterization of the far-infrared dust spectrum as the sum of two modified blackbodies (MBBs) serves as an important alternative to the commonly adopted single-MBB dust emission model. Analyzing the joint Planck/DIRBE dust spectrum, we show that two-component models provide a better fit to the 100-3000 GHz emission than do single-MBB models, though by a lesser margin than found by Finkbeiner et al. based on FIRAS and DIRBE. We also derive full-sky 6.'1 resolution maps of dust optical depth and temperature by fitting the two-component model to Planck 217-857 GHz along with DIRBE/IRAS 100 μm data. Because our two-component model matches the dust spectrum near its peak, accounts for the spectrum's flattening at millimeter wavelengths, and specifies dust temperature at 6.'1 FWHM, our model provides reliable, high-resolution thermal dust emission foreground predictions from 100 to 3000 GHz. We find that, in diffuse sky regions, our two-component 100-217 GHz predictions are on average accurate to within 2.2%, while extrapolating the Planck Collaboration et al. single-MBB model systematically underpredicts emission by 18.8% at 100 GHz, 12.6% at 143 GHz, and 7.9% at 217 GHz. We calibrate our two-component optical depth to reddening, and compare with reddening estimates based on stellar spectra. We find the dominant systematic problems in our temperature/reddening maps to be zodiacal light on large angular scales and the cosmic infrared background anisotropy on small angular scales.

  12. Mathematical model of the component mixture distribution in the molten cast iron during centrifugation (sedimentation)

    Science.gov (United States)

    Bikulov, R. A.; Kotlyar, L. M.

    2014-12-01

    For the development and management of the manufacturing processes of axisymmetric articles with compositional structure by centrifugal casting method [1,2,3,4] is necessary to create a generalized mathematical model of the dynamics of component mixture in the molten cast iron during centrifugation. In article. based on the analysis of the dynamics of two-component mixture at sedimentation, a method of successive approximations to determine the distribution of a multicomponent mixture by centrifugation in a parabolic crucible is developed.

  13. A Methodology for Modeling the Flow of Military Personnel Across Air Force Active and Reserve Components

    Science.gov (United States)

    2016-01-01

    for pilots will depend on the • number of active component pilots who separate • fraction of separating pilots who affiliate with the reserve ...when tracking economic output over a period of time. GDP data were collected from the Federal Reserve Economic Data (FRED), Federal Reserve Bank of St...C O R P O R A T I O N Research Report A Methodology for Modeling the Flow of Military Personnel Across Air Force Active and Reserve Components

  14. Assessing Internet addiction using the parsimonious Internet addiction components model - a preliminary study [forthcoming

    OpenAIRE

    Kuss, DJ; Shorter, GW; Van Rooij, AJ; Griffiths, MD; Schoenmakers, T.

    2014-01-01

    Internet usage has grown exponentially over the last decade. Research indicates that excessive Internet use can lead to symptoms associated with addiction. To date, assessment of potential Internet addiction has varied regarding populations studied and instruments used, making reliable prevalence estimations difficult. To overcome the present problems a preliminary study was conducted testing a parsimonious Internet addiction components model based on Griffiths’ addiction components (2005), i...

  15. 3-D inelastic analysis methods for hot section components. Volume 2: Advanced special functions models

    Science.gov (United States)

    Wilson, R. B.; Banerjee, P. K.

    1987-01-01

    This Annual Status Report presents the results of work performed during the third year of the 3-D Inelastic Analysis Methods for Hot Sections Components program (NASA Contract NAS3-23697). The objective of the program is to produce a series of computer codes that permit more accurate and efficient three-dimensional analyses of selected hot section components, i.e., combustor liners, turbine blades, and turbine vanes. The computer codes embody a progression of mathematical models and are streamlined to take advantage of geometrical features, loading conditions, and forms of material response that distinguish each group of selected components.

  16. Travelling wave solutions for some two-component shallow water models

    Science.gov (United States)

    Dutykh, Denys; Ionescu-Kruse, Delia

    2016-07-01

    In the present study we perform a unified analysis of travelling wave solutions to three different two-component systems which appear in shallow water theory. Namely, we analyze the celebrated Green-Naghdi equations, the integrable two-component Camassa-Holm equations and a new two-component system of Green-Naghdi type. In particular, we are interested in solitary and cnoidal-type solutions, as two most important classes of travelling waves that we encounter in applications. We provide a complete phase-plane analysis of all possible travelling wave solutions which may arise in these models. In particular, we show the existence of new type of solutions.

  17. Modeling Thermal Dust Emission with Two Components: Application to the Planck HFI Maps

    CERN Document Server

    Meisner, Aaron

    2014-01-01

    We apply the Finkbeiner et al. (1999) two-component thermal dust emission model to the Planck HFI maps. This parametrization of the far-infrared dust spectrum as the sum of two modified blackbodies serves as an important alternative to the commonly adopted single modified blackbody (MBB) dust emission model. Analyzing the joint Planck/DIRBE dust spectrum, we show that two-component models provide a better fit to the 100-3000 GHz emission than do single-MBB models, though by a lesser margin than found by Finkbeiner et al. (1999) based on FIRAS and DIRBE. We also derive full-sky 6.1' resolution maps of dust optical depth and temperature by fitting the two-component model to Planck 217-857 GHz along with DIRBE/IRAS 100 micron data. Because our two-component model matches the dust spectrum near its peak, accounts for the spectrum's flattening at millimeter wavelengths, and specifies dust temperature at 6.1' FWHM, our model provides reliable, high-resolution thermal dust emission foreground predictions from 100 to...

  18. A robust independent component analysis (ICA) model for functional magnetic resonance imaging (fMRI) data

    Science.gov (United States)

    Ao, Jingqi; Mitra, Sunanda; Liu, Zheng; Nutter, Brian

    2011-03-01

    The coupling of carefully designed experiments with proper analysis of functional magnetic resonance imaging (fMRI) data provides us with a powerful as well as noninvasive tool to help us understand cognitive processes associated with specific brain regions and hence could be used to detect abnormalities induced by a diseased state. The hypothesisdriven General Linear Model (GLM) and the data-driven Independent Component Analysis (ICA) model are the two most commonly used models for fMRI data analysis. A hybrid ICA-GLM model combines the two models to take advantages of benefits from both models to achieve more accurate mapping of the stimulus-induced activated brain regions. We propose a modified hybrid ICA-GLM model with probabilistic ICA that includes a noise model. In this modified hybrid model, a probabilistic principle component analysis (PPCA)-based component number estimation is used in the ICA stage to extract the intrinsic number of original time courses. In addition, frequency matching is introduced into the time course selection stage, along with temporal correlation, F-test based model fitting estimation, and time course combination, to produce a more accurate design matrix for GLM. A standard fMRI dataset is used to compare the results of applying GLM and the proposed hybrid ICA-GLM in generating activation maps.

  19. Characterizing and Modeling the Cost of Rework in a Library of Reusable Software Components

    Science.gov (United States)

    Basili, Victor R.; Condon, Steven E.; ElEmam, Khaled; Hendrick, Robert B.; Melo, Walcelio

    1997-01-01

    In this paper we characterize and model the cost of rework in a Component Factory (CF) organization. A CF is responsible for developing and packaging reusable software components. Data was collected on corrective maintenance activities for the Generalized Support Software reuse asset library located at the Flight Dynamics Division of NASA's GSFC. We then constructed a predictive model of the cost of rework using the C4.5 system for generating a logical classification model. The predictor variables for the model are measures of internal software product attributes. The model demonstrates good prediction accuracy, and can be used by managers to allocate resources for corrective maintenance activities. Furthermore, we used the model to generate proscriptive coding guidelines to improve programming, practices so that the cost of rework can be reduced in the future. The general approach we have used is applicable to other environments.

  20. The GNSS-R Eddy Experiment II: L-band and Optical Speculometry for Directional Sea-Roughness Retrieval from Low Altitude Aircraft

    CERN Document Server

    Germain, O; Soulat, F; Caparrini, M; Chapron, B; Silvestrin, P

    2003-01-01

    We report on the retrieval of directional sea-roughness (the full directional mean square slope, including MSS, direction and isotropy) through inversion of Global Navigation Satellite System Reflections (GNSS-R) and SOlar REflectance Speculometry (SORES)data collected during an experimental flight at 1000 m. The emphasis is on the utilization of the entire Delay-Doppler Map (for GNSS-R) or Tilt Azimuth Map (for SORES) in order to infer these directional parameters. Obtained estimations are analyzed and compared to Jason-1 measurements and the ECMWF numerical weather model.

  1. Formation mechanisms for low-altitude E{sub S} and their relationship with neutral Fe layers: Results from the METAL campaign

    Energy Technology Data Exchange (ETDEWEB)

    Kirkwood, S.; Von Zahn, U.

    1993-12-01

    This paper presents results from the METAL campaign, which was a study of sporadic E layers, and metal layers, in the lower altitude ionosphere, at high-latitude locations. Data was collected by a variety of instrumentation, including EISCAT UHF incoherent scatter radar, ionosondes, lidar, and rockets. A number of sporadic E layers were observed, and their origins were consistent with model results. These layers were observed to rapidly drop in altitude in many cases. When Fe layers were observed, they were not observed at exactly the same altitude, nor did they exhibit the same drift in altitude with time.

  2. Component temperatures inversion for remote sensing pixel based on directional thermal radiation model

    Institute of Scientific and Technical Information of China (English)

    王锦地; 李小文; 孙晓敏; 刘强

    2000-01-01

    When the remote sensing pixel is composed of multiple components and a non-isothermal surface, its directional signature of thermal-infrared radiation is mainly determined by the 3D structure of the pixel. In this paper, we present our simple directional thermal radiation model to describe the relation between the pixel thermal emission and the pixel’s component parameters, and invert the model to get the component temperatures. For the inversion algorithm, we focus on how to use the information of given observations in a more effective way. The information content in data space and parameter space is defined, and the transferring of information content in inversion procedure is studied. Our forward model and inversion method are validated using indoor directional measurement data.

  3. Component temperatures inversion for remote sensing pixel based on directional thermal radiation model

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    When the remote sensing pixel is composed of multiple components and a non-isothermal surface,its directional signature of thermal-infrared radiation is mainly determined by the 3D structure of the pixel.In this paper,we present our simple directional thermal radiation model to describe the relation between the pixel thermal emission and the pixel's component parameters,and invert the model to get the component temperatures.For the inversion algorithm,we focus on how to use the information of given observations in a more effective way.The information content in data space and parameter space is defined,and the transferring of information content in inversion procedure is studied.Our forward model and inversion method are validated using indoor directional measurement data.

  4. A Component-Based Modeling and Validation Method for PLC Systems

    Directory of Open Access Journals (Sweden)

    Rui Wang

    2014-05-01

    Full Text Available Programmable logic controllers (PLCs are complex embedded systems that are widely used in industry. This paper presents a component-based modeling and validation method for PLC systems using the behavior-interaction-priority (BIP framework. We designed a general system architecture and a component library for a type of device control system. The control software and hardware of the environment were all modeled as BIP components. System requirements were formalized as monitors. Simulation was carried out to validate the system model. A realistic example from industry of the gates control system was employed to illustrate our strategies. We found a couple of design errors during the simulation, which helped us to improve the dependability of the original systems. The results of experiment demonstrated the effectiveness of our approach.

  5. On testing an unspecified function through a linear mixed effects model with multiple variance components.

    Science.gov (United States)

    Wang, Yuanjia; Chen, Huaihou

    2012-12-01

    We examine a generalized F-test of a nonparametric function through penalized splines and a linear mixed effects model representation. With a mixed effects model representation of penalized splines, we imbed the test of an unspecified function into a test of some fixed effects and a variance component in a linear mixed effects model with nuisance variance components under the null. The procedure can be used to test a nonparametric function or varying-coefficient with clustered data, compare two spline functions, test the significance of an unspecified function in an additive model with multiple components, and test a row or a column effect in a two-way analysis of variance model. Through a spectral decomposition of the residual sum of squares, we provide a fast algorithm for computing the null distribution of the test, which significantly improves the computational efficiency over bootstrap. The spectral representation reveals a connection between the likelihood ratio test (LRT) in a multiple variance components model and a single component model. We examine our methods through simulations, where we show that the power of the generalized F-test may be higher than the LRT, depending on the hypothesis of interest and the true model under the alternative. We apply these methods to compute the genome-wide critical value and p-value of a genetic association test in a genome-wide association study (GWAS), where the usual bootstrap is computationally intensive (up to 10(8) simulations) and asymptotic approximation may be unreliable and conservative. © 2012, The International Biometric Society.

  6. Domain Walls and Textured Vortices in a Two-Component Ginzburg-Landau Model

    DEFF Research Database (Denmark)

    Madsen, Søren Peder; Gaididei, Yu. B.; Christiansen, Peter Leth

    2005-01-01

    We look for domain wall and textured vortex solutions in a two-component Ginzburg-Landau model inspired by two-band superconductivity. The two-dimensional two-component model, with equal coherence lengths and no magnetic field, shows some interesting properties. In the absence of a Josephson type...... coupling between the two order parameters a ''textured vortex'' is found by analytical and numerical solution of the Ginzburg-Landau equations. With a Josephson type coupling between the two order parameters we find the system to split up in two domains separated by a domain wall, where the order parameter...

  7. Towards a Complete Model for Software Component Deployment on Heterogeneous Platform

    Directory of Open Access Journals (Sweden)

    Švogor Ivan

    2014-12-01

    Full Text Available This report briefly describes an ongoing research related to optimization of allocating software components to heterogeneous computing platform (which includes CPU, GPU and FPGA. Research goal is also presented, along with current hot topics of the research area, related research teams, and finally results and contribution of my research. It involves mathematical modelling which results in goal function, optimization method which finds a suboptimal solution to the goal function and a software modeling tool which enables graphical representation of the problem at hand and help developers determine component placement in the system design phase.

  8. Domain Walls and Textured Vortices in a Two-Component Ginzburg-Landau Model

    DEFF Research Database (Denmark)

    Madsen, Søren Peder; Gaididei, Yu. B.; Christiansen, Peter Leth

    2005-01-01

    We look for domain wall and textured vortex solutions in a two-component Ginzburg-Landau model inspired by two-band superconductivity. The two-dimensional two-component model, with equal coherence lengths and no magnetic field, shows some interesting properties. In the absence of a Josephson type...... coupling between the two order parameters a ''textured vortex'' is found by analytical and numerical solution of the Ginzburg-Landau equations. With a Josephson type coupling between the two order parameters we find the system to split up in two domains separated by a domain wall, where the order parameter...

  9. Facilitating Performance Optimization of RF PCB Designs by using Parametric Finite-Element Component Models

    DEFF Research Database (Denmark)

    Rohde, John; Toftegaard, Thomas Skjødeberg

    2012-01-01

    Novel parametric finite-element models are provided for discrete SMD capacitors and inductors in the frequency range 100 MHz to 4 GHz. The aim of the models is to facilitate performance optimization and analysis of RF PCB designs integrating these SMD components with layout geometries...... such as antennas and PCB traces. The models presented are benchmarked against real-life measurements and conventional circuit models. Furthermore, two example parallel-resonance circuits are designed based on interpolation of the results and validated by measurements in order to demonstrate the accuracy...... of the presented modelling approach....

  10. A three-component model of the control error in manual tracking of continuous random signals.

    Science.gov (United States)

    Gerisch, Hans; Staude, Gerhard; Wolf, Werner; Bauch, Gerhard

    2013-10-01

    The performance of human operators acting within closed-loop control systems is investigated in a classic tracking task. The dependence of the control error (tracking error) on the parameters display gain, k(display), and input signal frequency bandwidth, f(g), which alter task difficulty and presumably the control delay, is studied with the aim of functionally specifying it via a model. The human operator as an element of a cascaded human-machine control system (e.g., car driving or piloting an airplane) codetermines the overall system performance. Control performance of humans in continuous tracking has been described in earlier studies. Using a handheld joystick, 10 participants tracked continuous random input signals. The parameters f(g) and k(display) were altered between experiments. Increased task difficulty promoted lengthened control delay and, consequently, increased control error.Tracking performance degraded profoundly with target deflection components above 1 Hz, confirming earlier reports. The control error is composed of a delay-induced component, a demand-based component, and a novel component: a human tracking limit. Accordingly, a new model that allows concepts of the observed control error to be split into these three components is suggested. To achieve optimal performance in control systems that include a human operator (e.g., vehicles, remote controlled rovers, crane control), (a) tasks should be kept as simple as possible to achieve shortest control delays, and (b) task components requiring higher-frequency (> 1 Hz) tracking actions should be avoided or automated by technical systems.

  11. A Dynamic Multinode Model for Component-Oriented Thermal Analysis of Flat-Plate Solar Collectors

    Directory of Open Access Journals (Sweden)

    Christoph N. Reiter

    2015-01-01

    Full Text Available A mathematical model of a flat-plate solar collector was developed on the basis of the physical principles of optics and heat transfer in order to determine collector’s component temperatures as well as collector efficiency. In contrast to many available models, the targeted use of this dynamic model is the detailed, theoretical investigation of the thermal behaviour of newly developed or adjusted collector designs on component level, for example, absorber, casing, or transparent cover. The defined model is based on a multinode network (absorber, fluid, glazing, and backside insulation containing the relevant physical equations to transfer the energy. The heat transfer network covers heat conduction, convection, and radiation. Furthermore, the collector optics is defined for the plane glazing and the absorber surface and also considers interactions between them. The model enables the variation of physical properties considering the geometric parameters and materials. Finally, the model was validated using measurement data and existing efficiency curve models. Both comparisons proved high accuracy of the developed model with deviation of up to 3% in collector efficiency and 1 K in component temperatures.

  12. Towards uncertainty quantification and parameter estimation for Earth system models in a component-based modeling framework

    Science.gov (United States)

    Peckham, Scott D.; Kelbert, Anna; Hill, Mary C.; Hutton, Eric W. H.

    2016-05-01

    Component-based modeling frameworks make it easier for users to access, configure, couple, run and test numerical models. However, they do not typically provide tools for uncertainty quantification or data-based model verification and calibration. To better address these important issues, modeling frameworks should be integrated with existing, general-purpose toolkits for optimization, parameter estimation and uncertainty quantification. This paper identifies and then examines the key issues that must be addressed in order to make a component-based modeling framework interoperable with general-purpose packages for model analysis. As a motivating example, one of these packages, DAKOTA, is applied to a representative but nontrivial surface process problem of comparing two models for the longitudinal elevation profile of a river to observational data. Results from a new mathematical analysis of the resulting nonlinear least squares problem are given and then compared to results from several different optimization algorithms in DAKOTA.

  13. Consequences of Transfusing Blood Components in Patients With Trauma: A Conceptual Model.

    Science.gov (United States)

    Jones, Allison R; Frazier, Susan K

    2017-04-01

    Transfusion of blood components is often required in resuscitation of patients with major trauma. Packed red blood cells and platelets break down and undergo chemical changes during storage (known as the storage lesion) that lead to an inflammatory response once the blood components are transfused to patients. Although some evidence supports a detrimental association between transfusion and a patient's outcome, the mechanisms connecting transfusion of stored components to outcomes remain unclear. The purpose of this review is to provide critical care nurses with a conceptual model to facilitate understanding of the relationship between the storage lesion and patients' outcomes after trauma; outcomes related to trauma, hemorrhage, and blood component transfusion are grouped according to those occurring in the short-term (≤30 days) and the long-term (>30 days). Complete understanding of these clinical implications is critical for practitioners in evaluating and treating patients given transfusions after traumatic injury.

  14. Vigor and Seedling Time of Tobacco Seed Produced in High and Low Altitudes%高低海拔生产的烟草种子其活力及出苗、成苗时间差异

    Institute of Scientific and Technical Information of China (English)

    宋碧清; 郑昀晔; 马文广; 牛永志; 索文龙; 李元君

    2014-01-01

    In order to investigate the possible difference of seed vigor and seedling of tobacco seed produced in high altitude and low altitude, the seeds of MS Yunyan 85, MS Yunyan 87 and MS K326 produced in low altitude (Banna) and high altitude such as Qujing and Zhaotong were germinated under room temperature (26℃) and low temperature (13 ℃), respectively. Comparison of emergence time and seedling time also were conducted in 6 tobacco-plant regions. The results showed that germination rate and germination percentage of seeds were almost the same under room temperature. The seed germination percentage of MS Yunyan 85 and MS Yunyan 87 produced in low altitude were higher than that in high altitude. The seeding time of all seeds was almost the same, which were sown in the same tobacco-plant region in the same year. The seedling time was the same. So the seed vigor and seedling rate of tobacco seed cannot be influenced by the altitude of seed production.%为阐明高海拔和低海拔产地生产的烟草种子是否存在活力及出苗差异,将低海拔产地(西双版纳)和高海拔产地(曲靖、昭通)生产的MS云烟85、MS云烟87、MS K326种子在光照培养箱中分别进行常温(26℃)、低温(13℃)萌发,2012—2013年分别在6个高海拔烟叶产区进行漂浮育苗,比较不同产地收获的种子室内发芽以及室外出苗和成苗速率。结果表明,不同海拔产地生产的烟草种子在常温下萌发,其发芽时间、发芽率没有明显差异,低温条件下,低海拔产地(西双版纳)生产的MS云烟85和MS云烟87种子的发芽率分别优于高海拔产地(曲靖、昭通)生产的种子;不同海拔产地生产的烟草种子在同一年份同一烟区的出苗时间差异不大,成苗时间相同。因此,种子产地的海拔高度不影响烟草种子的活力及出苗速率,种子活力的高低以及出苗的快慢与萌发及出苗时的温度有关。

  15. Effect of Colorspace Transformation, the Illuminance Component, and Color Modeling on Skin Detection

    Energy Technology Data Exchange (ETDEWEB)

    Jayaram, S; Schmugge, S; Shin, M C; Tsap, L V

    2004-03-22

    Skin detection is an important preliminary process in human motion analysis. It is commonly performed in three steps: transforming the pixel color to a non-RGB colorspace, dropping the illumination component of skin color, and classifying by modeling the skin color distribution. In this paper, we evaluate the effect of these three steps on the skin detection performance. The importance of this study is a new comprehensive colorspace and color modeling testing methodology that would allow for making the best choices for skin detection. Combinations of nine colorspaces, the presence of the absence of the illuminance component, and the two color modeling approaches are compared. The performance is measured by using a receiver operating characteristic (ROC) curve on a large dataset of 805 images with manual ground truth. The results reveal that (1) the absence of the illuminance component decreases performance, (2) skin color modeling has a greater impact than colorspace transformation, and (3) colorspace transformations can improve performance in certain instances. We found that the best performance was obtained by transforming the pixel color to the SCT, HSI, or CIELAB colorspaces, keeping the illuminance component, and modeling the color with the histogram approach.

  16. Low-altitude permafrost research in an overcooled talus slope-rock glacier system in the Romanian Carpathians (Detunata Goală, Apuseni Mountains)

    Science.gov (United States)

    Popescu, Răzvan; Vespremeanu-Stroe, Alfred; Onaca, Alexandru; Vasile, Mirela; Cruceru, Nicolae; Pop, Olimpiu

    2017-10-01

    Ground and air temperature monitoring, geophysical soundings and dendrological investigations were applied to a basaltic talus slope-rock glacier system from Detunata site in the Apuseni Mountains (Western Romanian Carpathians) to verify the presence of sporadic permafrost at 1020-1110 m asl, well below the regional limit of mountain permafrost. The near 0 °C mean annual ground surface temperatures imposed by the large negative annual thermal anomalies of the ground (up to 7.4 °C), together with the high resistivity values and the occurrence of trees with severe growth anomalies, support the presence of permafrost at this location. Temperature measurements and ground air circulation experiments proved that the so-called "chimney effect" is the main process favoring the ground overcooling and allowed for the construction of a model of ground air circulation in complex morphology deposits. The texture and porosity of the debris were quantified along with the local morphology in order to evaluate their role upon the chimney circulation. The debris porosity was found to be very high promoting intense ground overcooling during the cold season, including the periods of high snow cover due to the development of snow funnels. It efficiently reduces the heat transfer during summer thus contributing essentially to permafrost preservation. In compound morphologies, the depressed and low-lying features are the cold zones subjected to winter overcooling and summer chill, while the high-positioned and convex-up landforms become warm air evacuation features with positive thermal anomalies. Tree-ring measurements showed that the growth of cold-affected trees is higher during colder intervals (years to decades) probably as a consequence of the weakened katabatic air outflow during cooler summers. The dendrological analysis of multi-centennial spruces and their growth rates also provided palaeoclimatic inferences for the last 200 years. Dendrological data describe the multi

  17. Application and Progress on Low-altitude Unmanned Aerial Vehicle Remote Sensing%低空无人机遥感的应用及发展

    Institute of Scientific and Technical Information of China (English)

    高奋生

    2014-01-01

    Using the advanced unmanned aerial vehicle technology, remote sensing sensor technology, communications technology, GPS differential positioning technology and remote sensing application technology, UAV remote sensing automation realized intelligent, dedicated and rapid access to get space remote sensing information and complete the processing, modeling and application analysis of remote sensing data. In recent years, the Unmanned Aerial Vehicle (UAV) has been widely used in geological environment and disaster investigation, dynamic monitoring of land use, map updating and other fields. This paper analyzed the composition of UAV remote sensing systems and summarized the current problems of UAV remote sensing study, presenting the prospects of UAV remote sensing research focus and priorities in the future.%无人机遥感即是利用先进的无人驾驶飞行器技术、遥感传感器技术、通讯技术、GPS差分定位技术和遥感应用技术,实现自动化、智能化、专用化快速获取空间遥感信息,完成遥感数据处理、建模和应用分析的应用技术。近年来,无人机遥感系统已被广泛应用在地质环境与灾害调查、土地利用动态监测、地形图更新等领域。本文分析了无人机遥感系统的组成,归纳了目前无人机遥感研究存在的问题,展望了今后无人机遥感研究的热点和重点。

  18. Online path planning for UAV low-altitude penetration based on an improved differential evolution algorithm%基于改进差分进化算法的无人机在线低空突防航迹规划

    Institute of Scientific and Technical Information of China (English)

    彭志红; 孙琳; 陈杰

    2012-01-01

    为了解决无人机在部分未知敌对环境中的低空突防航迹规划问题,提出了一种改进的差分进化算法.该算法的进化模型采用冯·诺伊曼拓扑结构,并对其进行拓展,使种群在进化初期保持多样性,避免进化早期陷入局部最优,而进化后期加快收敛速度.该算法改进了差分进化算子中的变异操作,从而加快算法的收敛速度,快速找到多目标优化问题的最优解;同时,采用将绝对笛卡儿坐标和相对极坐标相结合的编码方式以提高搜索效率.将该算法用于无人机在线航迹规划仿真实验,并和未改进的算法结果作比较,验证了该算法的有效性.%An improved differential evolution algorithm was proposed for solving the online path planning problem of unmanned aerial vehicle (UAV) low-altitude penetration in partially known hostile environments. The algorithm adopts von Neumann topology and improves its structure to maintain the diversity of the population, prevent the population from falling into local optima in the early evolution and speed up the convergence rate in the later evolution as well. The mutation operator of differential evolution is improved to speed up the convergence rate of the algorithm, so that the optimal solution of the multi-objective optimization problem can be found quickly; the coding method combined the absolute Cartesian coordinates with the relative polar coordinates is used to improve the searching efficiency. The simulation experiment of online path planning for UAV low-altitude penetration shows that the proposed algorithm has a better performance than the unimproved differential evolution algorithm.

  19. Failure Predictions for VHTR Core Components using a Probabilistic Contiuum Damage Mechanics Model

    Energy Technology Data Exchange (ETDEWEB)

    Fok, Alex

    2013-10-30

    The proposed work addresses the key research need for the development of constitutive models and overall failure models for graphite and high temperature structural materials, with the long-term goal being to maximize the design life of the Next Generation Nuclear Plant (NGNP). To this end, the capability of a Continuum Damage Mechanics (CDM) model, which has been used successfully for modeling fracture of virgin graphite, will be extended as a predictive and design tool for the core components of the very high- temperature reactor (VHTR). Specifically, irradiation and environmental effects pertinent to the VHTR will be incorporated into the model to allow fracture of graphite and ceramic components under in-reactor conditions to be modeled explicitly using the finite element method. The model uses a combined stress-based and fracture mechanics-based failure criterion, so it can simulate both the initiation and propagation of cracks. Modern imaging techniques, such as x-ray computed tomography and digital image correlation, will be used during material testing to help define the baseline material damage parameters. Monte Carlo analysis will be performed to address inherent variations in material properties, the aim being to reduce the arbitrariness and uncertainties associated with the current statistical approach. The results can potentially contribute to the current development of American Society of Mechanical Engineers (ASME) codes for the design and construction of VHTR core components.

  20. EM Simulation Accuracy Enhancement for Broadband Modeling of On-Wafer Passive Components

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Jiang, Chenhui; Hadziabdic, Dzenan;

    2007-01-01

    This paper describes methods for accuracy enhancement in broadband modeling of on-wafer passive components using electromagnetic (EM) simulation. It is shown that standard excitation schemes for integrated component simulation leads to poor correlation with on-wafer measurements beyond the lower...... GHz frequency range. We show that this is due to parasitic effects and higher-order modes caused by the excitation schemes. We propose a simple equivalent circuit for the parasitic effects in the well-known ground ring excitation scheme. An extended L-2L calibration method is shown to improve...... significantly the accuracy of the on-wafer component modeling, when applied to parasitic effect removal associated with the excitation schemes....

  1. Single velocity-component modeling of leading edge turbulence interaction noise.

    Science.gov (United States)

    Gill, J; Zhang, X; Joseph, P

    2015-06-01

    A computational aeroacoustics approach is used to predict leading edge turbulence interaction noise for real airfoils. One-component (transverse), two-component (transverse and streamwise), and three-component (transverse, streamwise, and spanwise) synthesized turbulence disturbances are modeled instead of harmonic transverse gusts, to which previous computational studies of leading edge noise have often been confined. The effects of the inclusion of streamwise and spanwise disturbances on the noise are assessed. It is shown that accurate noise predictions can be made by modeling only transverse disturbances which reduces the computational expense of simulations. The accuracy of using only transverse disturbances is assessed for symmetric and cambered airfoils, and also for airfoils at non-zero angle of attack.

  2. Modeling of the heliospheric interface: multi-component nature of the heliospheric plasma

    CERN Document Server

    Malama, Y G; Chalov, S V; Malama, Yury G.; Izmodenov, Vlad V.; Chalov, Sergey V.

    2005-01-01

    We present a new model of the heliospheric interface - the region of the solar wind interaction with the local interstellar medium. This new model performs a multi-component treatment of charged particles in the heliosphere. All charged particles are divided into several co-moving types. The coldest type, with parameters typical of original solar wind protons, is considered in the framework of fluid approximation. The hot pickup proton components created from interstellar H atoms and heliospheric ENAs by charge exchange, electron impact ionization and photoionization are treated kinetically. The charged components are considered self-consistently with interstellar H atoms, which are described kinetically as well. To solve the kinetic equation for H atoms we use the Monte Carlo method with splitting of trajectories, which allows us 1) to reduce statistical uncertainties allowing correct interpretation of observational data, 2) to separate all H atoms in the heliosphere into several populations depending on the...

  3. Modelling autotrophic and heterotrophic components of soil respiration in wheat fields

    Science.gov (United States)

    Delogu, E.; LeDantec, V.; Buysse, P.; Mordelet, P.; Aubinet, M.

    2012-04-01

    Partitioning soil respiration into its heterotrophic and autotrophic components is a current key challenge to improve understanding of soil processes in croplands. For this purpose, we coupled a daily-time step soil organic carbon model derived from the CENTURY (Parton et al, 1987) calculating carbon turnover and carbon dioxide production in the soil with root sub-model from the plant process-based model CASTANEA (Dufrêne et al, 2005). In the Century model, soil organic carbon is divided into three major components including active, slow and passive soil carbon. Each pool has its own decomposition constant. Carbon flows between these pools are controlled by carbon inputs (crop residue), decomposition rate and microbial respiration loss parameters, both of which are a function of soil texture, soil temperature and soil water content. The model assumes that all C decompositions flows are associated with microbial activity and that microbial respiration occurs for each of these flows. Heterotrophic soil respiration is the sum of all these microbial respiration processes. To simulate autotrophic component, maintenance respiration is calculated from the nitrogen content and assuming an exponential relationship to account for temperature dependence. Growth respiration is calculated assuming that daily growth respiration depends on both growth rate and construction cost of the considered organ. To investigate model performances, simulations of soil CO2 efflux were compared with 3 datasets recorded in three different fields under different soil and climate conditions. Soil respiration measurements were performed on three winter wheat crops on Lamasquère (2007) and Auradé (2008), South-West France and in Lonzée (2007), Belgium. The French sites data come from manual measurement chambers, PP systems. The Belgium site is equipped with an automatic (half-hour resolution time) measurement system. The model was run on the three climatic years of data on bare soil and a first

  4. Technique for Early Reliability Prediction of Software Components Using Behaviour Models

    Science.gov (United States)

    Ali, Awad; N. A. Jawawi, Dayang; Adham Isa, Mohd; Imran Babar, Muhammad

    2016-01-01

    Behaviour models are the most commonly used input for predicting the reliability of a software system at the early design stage. A component behaviour model reveals the structure and behaviour of the component during the execution of system-level functionalities. There are various challenges related to component reliability prediction at the early design stage based on behaviour models. For example, most of the current reliability techniques do not provide fine-grained sequential behaviour models of individual components and fail to consider the loop entry and exit points in the reliability computation. Moreover, some of the current techniques do not tackle the problem of operational data unavailability and the lack of analysis results that can be valuable for software architects at the early design stage. This paper proposes a reliability prediction technique that, pragmatically, synthesizes system behaviour in the form of a state machine, given a set of scenarios and corresponding constraints as input. The state machine is utilized as a base for generating the component-relevant operational data. The state machine is also used as a source for identifying the nodes and edges of a component probabilistic dependency graph (CPDG). Based on the CPDG, a stack-based algorithm is used to compute the reliability. The proposed technique is evaluated by a comparison with existing techniques and the application of sensitivity analysis to a robotic wheelchair system as a case study. The results indicate that the proposed technique is more relevant at the early design stage compared to existing works, and can provide a more realistic and meaningful prediction. PMID:27668748

  5. Technique for Early Reliability Prediction of Software Components Using Behaviour Models.

    Science.gov (United States)

    Ali, Awad; N A Jawawi, Dayang; Adham Isa, Mohd; Imran Babar, Muhammad

    Behaviour models are the most commonly used input for predicting the reliability of a software system at the early design stage. A component behaviour model reveals the structure and behaviour of the component during the execution of system-level functionalities. There are various challenges related to component reliability prediction at the early design stage based on behaviour models. For example, most of the current reliability techniques do not provide fine-grained sequential behaviour models of individual components and fail to consider the loop entry and exit points in the reliability computation. Moreover, some of the current techniques do not tackle the problem of operational data unavailability and the lack of analysis results that can be valuable for software architects at the early design stage. This paper proposes a reliability prediction technique that, pragmatically, synthesizes system behaviour in the form of a state machine, given a set of scenarios and corresponding constraints as input. The state machine is utilized as a base for generating the component-relevant operational data. The state machine is also used as a source for identifying the nodes and edges of a component probabilistic dependency graph (CPDG). Based on the CPDG, a stack-based algorithm is used to compute the reliability. The proposed technique is evaluated by a comparison with existing techniques and the application of sensitivity analysis to a robotic wheelchair system as a case study. The results indicate that the proposed technique is more relevant at the early design stage compared to existing works, and can provide a more realistic and meaningful prediction.

  6. [Building artificial neural networks model on portable NIR integrity wheat component measuring apparatus].

    Science.gov (United States)

    Ji, Hai-yan; Wen, Ming; Hao, Bin

    2006-01-01

    The quantitative analysis model of protein in integrity wheat was built by three layers back propagation artificial neural networks for portable near infrared (NIR) integrity wheat component measuring apparatus. The structure diagram of integrity wheat component measuring apparatus, light route structure of apparatus and the spectrum of integrity wheat were given in the present paper. The theory of artificial neural network was briefly introduced and the results of quantitative analysis model of protein were given. For calibration set and prediction set, the correlation coefficient was 0.90 and 0.96 respectively; the relative standard deviation is 3.77% and 4.46% respectively. Because of the influence of light route structure, electrical circuit, and integrity sample forms on the measuring apparatus, some nonlinearity exists between the spectral parameters and chemical values. The results of artificial neural networks nonlinear model were superior to linear model.

  7. Photonic Beamformer Model Based on Analog Fiber-Optic Links’ Components

    Science.gov (United States)

    Volkov, V. A.; Gordeev, D. A.; Ivanov, S. I.; Lavrov, A. P.; Saenko, I. I.

    2016-08-01

    The model of photonic beamformer for wideband microwave phased array antenna is investigated. The main features of the photonic beamformer model based on true-time-delay technique, DWDM technology and fiber chromatic dispersion are briefly analyzed. The performance characteristics of the key components of photonic beamformer for phased array antenna in the receive mode are examined. The beamformer model composed of the components available on the market of fiber-optic analog communication links is designed and tentatively investigated. Experimental demonstration of the designed model beamforming features includes actual measurement of 5-element microwave linear array antenna far-field patterns in 6-16 GHz frequency range for antenna pattern steering up to 40°. The results of experimental testing show good accordance with the calculation estimates.

  8. Alternative models for determining the surface energy components in offset printing.

    Science.gov (United States)

    Järn, M; Tåg, C-M; Järnström, J; Granqvist, B; Rosenholm, J B

    2006-09-15

    Different ways of calculating surface energy components for substrates used in offset printing are compared. The results of the very useful van Oss-Chaudhury-Good bi-bidentate model (vOCG) are simplified to mono-bidentate and mono-monodentate models. The unbalance in the acid-base values often obtained by the vOCG model is strongly reduced when applying the simple mono-monodentate model. Moreover, the frequently encountered problem of negative square roots of the acid and base components is removed. An attempt to describe the ink transfer during offset printing by calculating theoretical works of adhesion between ink/plate and ink/paper is also made. The effect of paper roughness on the wetting was studied with atomic force microscopy (AFM).

  9. Framework based on MDA and ontology for the representation and validation of components model

    Directory of Open Access Journals (Sweden)

    Nemury Silega-Martínez

    2014-05-01

    Full Text Available Model Driven Architecture is one of the most prominent proposals in the area of software development, accepted by both the research community and software development industry. Moreover, in recent years have shown the potential of ontologies for representing a particular domain, example of this are the results in the semantic web. In this paper we present a proposal based on Model Driven Architecture paradigm and is complemented with ontology to represent and validate component models. This component model is restricted to the development of business management systems, so it includes concepts from that domain. The use of the framework will reduce the number of errors made during the development of the system architecture, will increase standardization and productivity at this stage.

  10. Credit Risk Assessment Model Based Using Principal component Analysis And Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Hamdy Abeer

    2016-01-01

    Full Text Available Credit risk assessment for bank customers has gained increasing attention in recent years. Several models for credit scoring have been proposed in the literature for this purpose. The accuracy of the model is crucial for any financial institution’s profitability. This paper provided a high accuracy credit scoring model that could be utilized with small and large datasets utilizing a principal component analysis (PCA based breakdown to the significance of the attributes commonly used in the credit scoring models. The proposed credit scoring model applied PCA to acquire the main attributes of the credit scoring data then an ANN classifier to determine the credit worthiness of an individual applicant. The performance of the proposed model was compared to other models in terms of accuracy and training time. Results, based on German dataset showed that the proposed model is superior to others and computationally cheaper. Thus it can be a potential candidate for future credit scoring systems.

  11. 多光谱低空遥感图像光照辐射度校正%Radiometric calibration of low altitude multispectral remote sensing images

    Institute of Scientific and Technical Information of China (English)

    汪沛; 张俊雄; 兰玉彬; 周志艳; 罗锡文

    2014-01-01

    includes the development of micro UAV remote sensing platforms, information acquisition technology, image processing, and analysis and application of crop management, is reviewed in this paper. Micro UAV mainly has two types: rotor helicopter and fixed-wing aircraft. The rotor helicopter has been used more widely in acquiring information of the field, because it has the ability of taking off and landing vertically, fixed-point hovering, and slow cruising. Japan was the first country that has used the micro-UAV in agricultural production, and is one of the countries that have the best and most mature technologies in using remote UAV in agriculture today. The United States, Netherlands, Israel, and the United Kingdom also have a very good development all over the world. The beginning of research and development of micro UAV in China was much later than the other developed countries, but it has a booming development and grows rapidly. In this paper, parameters and characteristics of different models of the micro UAVs from eight companies in China have been listed for comparison. In remote sensing information acquiring systems, due to the limited load capacity of micro-UAV, digital camera and light-weight multispectral camera are two main instruments that are used on micro UAV for remote sensing information acquiring. How to adjust the posture of airborne remote sensors quickly and accurately so that the detecting target is always in the center of monitoring view, and how to realize remote controlling, image and information capturing, and transmission wirelessly are some of the focuses of UAV remote sensing technology at present. Limited by the stability and load capacity of the micro UAV, the remote sensing image always appears with the defects including a small view, large angle inclination, and serious irregular image overlap. So, solving the problem of correction, matching, mosaicing, fusing, and analyzing of the remote sensing images is one of the most important research

  12. Extending generalized linear models with random effects and components of dispersion.

    NARCIS (Netherlands)

    Engel, B.

    1997-01-01

    This dissertation was born out of a need for general and numerically feasible procedures for inference in variance components models for non-normal data. The methodology should be widely applicable within the institutes of the Agricultural Research Department (DLO) of the Dutch Ministry of Agricultu

  13. A model for determining condition-based maintenance policies for deteriorating multi-component systems

    NARCIS (Netherlands)

    Hontelez, J.A.M.; Wijnmalen, D.J.D.

    1993-01-01

    We discuss a method to determine strategies for preventive maintenance of systems consisting of gradually deteriorating components. A model has been developed to compute not only the range of conditions inducing a repair action, but also inspection moments based on the last known condition value so

  14. Ontologies to Support RFID-Based Link between Virtual Models and Construction Components

    DEFF Research Database (Denmark)

    Sørensen, Kristian Birch; Christiansson, Per; Svidt, Kjeld

    2010-01-01

    the virtual models and the physical components in the construction process can improve the information handling and sharing in construction and building operation management. Such a link can be created by means of Radio Frequency Identification (RFID) technology. Ontologies play an important role...

  15. Particle Markov Chain Monte Carlo Techniques of Unobserved Component Time Series Models Using Ox

    DEFF Research Database (Denmark)

    Nonejad, Nima

    This paper details Particle Markov chain Monte Carlo techniques for analysis of unobserved component time series models using several economic data sets. PMCMC combines the particle filter with the Metropolis-Hastings algorithm. Overall PMCMC provides a very compelling, computationally fast...

  16. Properties of and algorithms for fitting three-way component models with offset terms

    NARCIS (Netherlands)

    Kiers, Henk A. L.

    2006-01-01

    Prior to a three-way component analysis of a three-way data set, it is customary to preprocess the data by centering and/or rescaling them. Harshman and Lundy (1984) considered that three-way data actually consist of a three-way model part, which in fact pertains to ratio scale measurements, as welt

  17. Helpful Components Involved in the Cognitive-Experiential Model of Dream Work

    Science.gov (United States)

    Tien, Hsiu-Lan Shelley; Chen, Shuh-Chi; Lin, Chia-Huei

    2009-01-01

    The purpose of the study was to examine the helpful components involved in the Hill's cognitive-experiential dream work model. Participants were 27 volunteer clients from colleges and universities in northern and central parts of Taiwan. Each of the clients received 1-2 sessions of dream interpretations. The cognitive-experiential dream work model…

  18. Analysis of whisker-toughened CMC structural components using an interactive reliability model

    Science.gov (United States)

    Duffy, Stephen F.; Palko, Joseph L.

    1992-01-01

    Realizing wider utilization of ceramic matrix composites (CMC) requires the development of advanced structural analysis technologies. This article focuses on the use of interactive reliability models to predict component probability of failure. The deterministic William-Warnke failure criterion serves as theoretical basis for the reliability model presented here. The model has been implemented into a test-bed software program. This computer program has been coupled to a general-purpose finite element program. A simple structural problem is presented to illustrate the reliability model and the computer algorithm.

  19. Verification of the component accuracy prediction obtained by physical modelling and the elastic simulation of the die/component interaction

    DEFF Research Database (Denmark)

    Ravn, Bjarne Gottlieb; Andersen, Claus Bo; Wanheim, Tarras

    2001-01-01

    There are three demands on a component that must undergo a die-cavity elasticity analysis. The demands to the product are specified as: (i) to be able to measure the loading profile which results in elestic die-cavity deflections; (ii) to be able to compute the elestic deflections using FE; (iii...

  20. Verification of the component accuracy prediction obtained by physical modelling and the elastic simulation of the die/component interaction

    DEFF Research Database (Denmark)

    Ravn, Bjarne Gottlieb; Andersen, Claus Bo; Wanheim, Tarras

    2001-01-01

    There are three demands on a component that must undergo a die-cavity elasticity analysis. The demands to the product are specified as: (i) to be able to measure the loading profile which results in elestic die-cavity deflections; (ii) to be able to compute the elestic deflections using FE; (iii)...

  1. Two-component model of the interaction of an interstellar cloud with surrounding hot plasma

    OpenAIRE

    Provornikova, E. A.; Izmodenov, V. V.; Lallement, R.

    2011-01-01

    We present a two-component gasdynamic model of an interstellar cloud embedded in a hot plasma. It is assumed that the cloud consists of atomic hydrogen gas, interstellar plasma is quasineutral. Hydrogen atoms and plasma protons interact through a charge exchange process. Magnetic felds and radiative processes are ignored in the model. The influence of heat conduction within plasma on the interaction between a cloud and plasma is studied. We consider the extreme case and assume that hot plasma...

  2. Modelling Earth's surface topography: decomposition of the static and dynamic components

    DEFF Research Database (Denmark)

    Guerri, Mattia; Cammarano, Fabio; Tackley, Paul J.

    2016-01-01

    Contrasting results on the magnitude of the dynamic component of topography motivate us to analyse the sources of uncertainties affecting long wavelength topography modelling. We obtain a range of mantle density structures from thermo-chemical interpretation of available seismic tomography models...... too large. A truly interdisciplinary approach, combining constraints from the geological record with a multi-methodological interpretation of geophysical observations, is required to tackle the challenging task of linking the surface topography to deep processes....

  3. Embedded System Construction: Evaluation of a Model-Driven and Component-Based Develpoment Approach

    OpenAIRE

    Bunse, C.; Gross, H.G.; Peper, C. (Claudia)

    2008-01-01

    Preprint of paper published in: Models in Software Engineering, Lecture Notes in Computer Science 5421, 2009; doi:10.1007/978-3-642-01648-6_8 Model-driven development has become an important engineering paradigm. It is said to have many advantages over traditional approaches, such as reuse or quality improvement, also for embedded systems. Along a similar line of argumentation, component-based software engineering is advocated. In order to investigate these claims, the MARMOT method was appli...

  4. Swelling in light water reactor internal components: Insights from computational modeling

    Energy Technology Data Exchange (ETDEWEB)

    Stoller, Roger E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Barashev, Alexander V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Golubov, Stanislav I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-08-01

    A modern cluster dynamics model has been used to investigate the materials and irradiation parameters that control microstructural evolution under the relatively low-temperature exposure conditions that are representative of the operating environment for in-core light water reactor components. The focus is on components fabricated from austenitic stainless steel. The model accounts for the synergistic interaction between radiation-produced vacancies and the helium that is produced by nuclear transmutation reactions. Cavity nucleation rates are shown to be relatively high in this temperature regime (275 to 325°C), but are sensitive to assumptions about the fine scale microstructure produced under low-temperature irradiation. The cavity nucleation rates observed run counter to the expectation that void swelling would not occur under these conditions. This expectation was based on previous research on void swelling in austenitic steels in fast reactors. This misleading impression arose primarily from an absence of relevant data. The results of the computational modeling are generally consistent with recent data obtained by examining ex-service components. However, it has been shown that the sensitivity of the model s predictions of low-temperature swelling behavior to assumptions about the primary damage source term and specification of the mean-field sink strengths is somewhat greater that that observed at higher temperatures. Further assessment of the mathematical model is underway to meet the long-term objective of this research, which is to provide a predictive model of void swelling at relevant lifetime exposures to support extended reactor operations.

  5. Applying Reflective Middleware Techniques to Optimize a QoS-enabled CORBA Component Model Implementation

    Science.gov (United States)

    Wang, Nanbor; Parameswaran, Kirthika; Kircher, Michael; Schmidt, Douglas

    2003-01-01

    Although existing CORBA specifications, such as Real-time CORBA and CORBA Messaging, address many end-to-end quality-of service (QoS) properties, they do not define strategies for configuring these properties into applications flexibly, transparently, and adaptively. Therefore, application developers must make these configuration decisions manually and explicitly, which is tedious, error-prone, and open sub-optimal. Although the recently adopted CORBA Component Model (CCM) does define a standard configuration framework for packaging and deploying software components, conventional CCM implementations focus on functionality rather than adaptive quality-of-service, which makes them unsuitable for next-generation applications with demanding QoS requirements. This paper presents three contributions to the study of middleware for QoS-enabled component-based applications. It outlines rejective middleware techniques designed to adaptively (1) select optimal communication mechanisms, (2) manage QoS properties of CORBA components in their contain- ers, and (3) (re)con$gure selected component executors dynamically. Based on our ongoing research on CORBA and the CCM, we believe the application of rejective techniques to component middleware will provide a dynamically adaptive and (re)configurable framework for COTS software that is well-suited for the QoS demands of next-generation applications.

  6. Abrupt Strategy Change Underlies Gradual Performance Change: Bayesian Hierarchical Models of Component and Aggregate Strategy Use.

    Science.gov (United States)

    Wynton, Sarah K A; Anglim, Jeromy

    2017-04-10

    While researchers have often sought to understand the learning curve in terms of multiple component processes, few studies have measured and mathematically modeled these processes on a complex task. In particular, there remains a need to reconcile how abrupt changes in strategy use can co-occur with gradual changes in task completion time. Thus, the current study aimed to assess the degree to which strategy change was abrupt or gradual, and whether strategy aggregation could partially explain gradual performance change. It also aimed to show how Bayesian methods could be used to model the effect of practice on strategy use. To achieve these aims, 162 participants completed 15 blocks of practice on a complex computer-based task-the Wynton-Anglim booking (WAB) task. The task allowed for multiple component strategies (i.e., memory retrieval, information reduction, and insight) that could also be aggregated to a global measure of strategy use. Bayesian hierarchical models were used to compare abrupt and gradual functions of component and aggregate strategy use. Task completion time was well-modeled by a power function, and global strategy use explained substantial variance in performance. Change in component strategy use tended to be abrupt, whereas change in global strategy use was gradual and well-modeled by a power function. Thus, differential timing of component strategy shifts leads to gradual changes in overall strategy efficiency, and this provides one reason for why smooth learning curves can co-occur with abrupt changes in strategy use. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  7. Estimating Modifying Effect of Age on Genetic and Environmental Variance Components in Twin Models.

    Science.gov (United States)

    He, Liang; Sillanpää, Mikko J; Silventoinen, Karri; Kaprio, Jaakko; Pitkäniemi, Janne

    2016-04-01

    Twin studies have been adopted for decades to disentangle the relative genetic and environmental contributions for a wide range of traits. However, heritability estimation based on the classical twin models does not take into account dynamic behavior of the variance components over age. Varying variance of the genetic component over age can imply the existence of gene-environment (G×E) interactions that general genome-wide association studies (GWAS) fail to capture, which may lead to the inconsistency of heritability estimates between twin design and GWAS. Existing parametricG×Einteraction models for twin studies are limited by assuming a linear or quadratic form of the variance curves with respect to a moderator that can, however, be overly restricted in reality. Here we propose spline-based approaches to explore the variance curves of the genetic and environmental components. We choose the additive genetic, common, and unique environmental variance components (ACE) model as the starting point. We treat the component variances as variance functions with respect to age modeled by B-splines or P-splines. We develop an empirical Bayes method to estimate the variance curves together with their confidence bands and provide an R package for public use. Our simulations demonstrate that the proposed methods accurately capture dynamic behavior of the component variances in terms of mean square errors with a data set of >10,000 twin pairs. Using the proposed methods as an alternative and major extension to the classical twin models, our analyses with a large-scale Finnish twin data set (19,510 MZ twins and 27,312 DZ same-sex twins) discover that the variances of the A, C, and E components for body mass index (BMI) change substantially across life span in different patterns and the heritability of BMI drops to ∼50% after middle age. The results further indicate that the decline of heritability is due to increasing unique environmental variance, which provides more

  8. Calculation and Analysis of Magnetic Gradient Tensor Components of Global Magnetic Models

    Science.gov (United States)

    Schiffler, M.; Queitsch, M.; Schneider, M.; Goepel, A.; Stolz, R.; Krech, W.; Meyer, H. G.; Kukowski, N.

    2014-12-01

    Global Earth's magnetic field models like the International Geomagnetic Reference Field (IGRF), the World Magnetic Model (WMM) or the High Definition Geomagnetic Model (HDGM) are harmonic analysis regressions to available magnetic observations stored as spherical harmonic coefficients. Input data combine recordings from magnetic observatories, airborne magnetic surveys and satellite data. The advance of recent magnetic satellite missions like SWARM and its predecessors like CHAMP offer high resolution measurements while providing a full global coverage. This deserves expansion of the theoretical framework of harmonic synthesis to magnetic gradient tensor components. Measurement setups for Full Tensor Magnetic Gradiometry equipped with high sensitive gradiometers like the JeSSY STAR system can directly measure the gradient tensor components, which requires precise knowledge about the background regional gradients which can be calculated with this extension. In this study we develop the theoretical framework for calculation of the magnetic gradient tensor components from the harmonic series expansion and apply our approach to the IGRF and HDGM. The gradient tensor component maps for entire Earth's surface produced for the IGRF show low gradients reflecting the variation from the dipolar character, whereas maps for the HDGM (up to degree N=729) reveal new information about crustal structure, especially across the oceans, and deeply situated ore bodies. From the gradient tensor components, the rotational invariants, the Eigenvalues, and the normalized source strength (NSS) are calculated. The NSS focuses on shallower and stronger anomalies. Euler deconvolution using either the tensor components or the NSS applied to the HDGM reveals an estimate of the average source depth for the entire magnetic crust as well as individual plutons and ore bodies. The NSS reveals the boundaries between the anomalies of major continental provinces like southern Africa or the Eastern

  9. The component alignment model: a new approach to health care information technology strategic planning.

    Science.gov (United States)

    Martin, J B; Wilkins, A S; Stawski, S K

    1998-08-01

    The evolving health care environment demands that health care organizations fully utilize information technologies (ITs). The effective deployment of IT requires the development and implementation of a comprehensive IT strategic plan. A number of approaches to health care IT strategic planning exist, but they are outdated or incomplete. The component alignment model (CAM) introduced here recognizes the complexity of today's health care environment, emphasizing continuous assessment and realignment of seven basic components: external environment, emerging ITs, organizational infrastructure, mission, IT infrastructure, business strategy, and IT strategy. The article provides a framework by which health care organizations can develop an effective IT strategic planning process.

  10. Independent component feature-based human activity recognition via Linear Discriminant Analysis and Hidden Markov Model.

    Science.gov (United States)

    Uddin, Md; Lee, J J; Kim, T S

    2008-01-01

    In proactive computing, human activity recognition from image sequences is an active research area. This paper presents a novel approach of human activity recognition based on Linear Discriminant Analysis (LDA) of Independent Component (IC) features from shape information. With extracted features, Hidden Markov Model (HMM) is applied for training and recognition. The recognition performance using LDA of IC features has been compared to other approaches including Principle Component Analysis (PCA), LDA of PC, and ICA. The preliminary results show much improved performance in the recognition rate with our proposed method.

  11. Evaluation of the Component Chemical Potentials in Analytical Models for Ordered Alloy Phases

    Directory of Open Access Journals (Sweden)

    W. A. Oates

    2011-01-01

    Full Text Available The component chemical potentials in models of solution phases with a fixed number of sites can be evaluated easily when the Helmholtz energy is known as an analytical function of composition. In the case of ordered phases, however, the situation is less straightforward, because the Helmholtz energy is a functional involving internal order parameters. Because of this, the chemical potentials are usually obtained numerically from the calculated integral Helmholtz energy. In this paper, we show how the component chemical potentials can be obtained analytically in ordered phases via the use of virtual cluster chemical potentials. Some examples are given which illustrate the simplicity of the method.

  12. A Stochastic Restricted Principal Components Regression Estimator in the Linear Model

    Directory of Open Access Journals (Sweden)

    Daojiang He

    2014-01-01

    Full Text Available We propose a new estimator to combat the multicollinearity in the linear model when there are stochastic linear restrictions on the regression coefficients. The new estimator is constructed by combining the ordinary mixed estimator (OME and the principal components regression (PCR estimator, which is called the stochastic restricted principal components (SRPC regression estimator. Necessary and sufficient conditions for the superiority of the SRPC estimator over the OME and the PCR estimator are derived in the sense of the mean squared error matrix criterion. Finally, we give a numerical example and a Monte Carlo study to illustrate the performance of the proposed estimator.

  13. The Influence of Internal Structures in Fused Deposition Modeling Method on Dimensional Accuracy of Components

    Directory of Open Access Journals (Sweden)

    Milde Ján

    2016-09-01

    Full Text Available The paper investigates the influence of infill (internal structures of components in the Fused Deposition Modeling (FDM method on dimensional and geometrical accuracy of components. The components in this case were real models of human mandible, which were obtained by Computed Tomography (CT mostly used in medical applications. In the production phase, the device used for manufacturing, was a 3D printer Zortrax M200 based on the FDM technology. In the second phase, the mandibles made by the printer, were digitized using optical scanning device of GOM ATOS Triple Scan II. They were subsequently evaluated in the final phase. The practical part of this article describes the procedure of jaw model modification, the production of components using a 3D printer, the procedure of digitization of printed parts by optical scanning device and the procedure of comparison. The outcome of this article is a comparative analysis of individual printed parts, containing tables with mean deviations for individual printed parts, as well as tables for groups of printed parts with the same infill parameter.

  14. Analysis of Dynamic Interactions between Different Drivetrain Components with a Detailed Wind Turbine Model

    Science.gov (United States)

    Bartschat, A.; Morisse, M.; Mertens, A.; Wenske, J.

    2016-09-01

    The presented work describes a detailed analysis of the dynamic interactions among mechanical and electrical drivetrain components of a modern wind turbine under the influence of parameter variations, different control mechanisms and transient excitations. For this study, a detailed model of a 2MW wind turbine with a gearbox, a permanent magnet synchronous generator and a full power converter has been developed which considers all relevant characteristics of the mechanical and electrical subsystems. This model includes an accurate representation of the aerodynamics and the mechanical properties of the rotor and the complete mechanical drivetrain. Furthermore, a detailed electrical modelling of the generator, the full scale power converter with discrete switching devices, its filters, the transformer and the grid as well as the control structure is considered. The analysis shows that, considering control measures based on active torsional damping, interactions between mechanical and electrical subsystems can significantly affect the loads and thus the individual lifetime of the components.

  15. Three-Component Power Decomposition for Polarimetric SAR Data Based on Adaptive Volume Scatter Modeling

    Directory of Open Access Journals (Sweden)

    Sang-Eun Park

    2012-05-01

    Full Text Available In this paper, the three-component power decomposition for polarimetric SAR (PolSAR data with an adaptive volume scattering model is proposed. The volume scattering model is assumed to be reflection-symmetric but parameterized. For each image pixel, the decomposition first starts with determining the adaptive parameter based on matrix similarity metric. Then, a respective scattering power component is retrieved with the established procedure. It has been shown that the proposed method leads to complete elimination of negative powers as the result of the adaptive volume scattering model. Experiments with the PolSAR data from both the NASA/JPL (National Aeronautics and Space Administration/Jet Propulsion Laboratory Airborne SAR (AIRSAR and the JAXA (Japan Aerospace Exploration Agency ALOS-PALSAR also demonstrate that the proposed method not only obtains similar/better results in vegetated areas as compared to the existing Freeman-Durden decomposition but helps to improve discrimination of the urban regions.

  16. Advanced parametrical modelling of 24 GHz radar sensor IC packaging components

    Science.gov (United States)

    Kazemzadeh, R.; John, W.; Wellmann, J.; Bala, U. B.; Thiede, A.

    2011-08-01

    This paper deals with the development of an advanced parametrical modelling concept for packaging components of a 24 GHz radar sensor IC used in automotive driver assistance systems. For fast and efficient design of packages for system-in-package modules (SiP), a simplified model for the description of parasitic electromagnetic effects within the package is desirable, as 3-D field computation becomes inefficient due to the high density of conductive elements of the various signal paths in the package. By using lumped element models for the characterization of the conductive components, a fast indication of the design's signal-quality can be gained, but so far does not offer enough flexibility to cover the whole range of geometric arrangements of signal paths in a contemporary package. This work pursues to meet the challenge of developing a flexible and fast package modelling concept by defining parametric lumped-element models for all basic signal path components, e.g. bond wires, vias, strip lines, bumps and balls.

  17. Sub-component modeling for face image reconstruction in video communications

    Science.gov (United States)

    Shiell, Derek J.; Xiao, Jing; Katsaggelos, Aggelos K.

    2008-08-01

    Emerging communications trends point to streaming video as a new form of content delivery. These systems are implemented over wired systems, such as cable or ethernet, and wireless networks, cell phones, and portable game systems. These communications systems require sophisticated methods of compression and error-resilience encoding to enable communications across band-limited and noisy delivery channels. Additionally, the transmitted video data must be of high enough quality to ensure a satisfactory end-user experience. Traditionally, video compression makes use of temporal and spatial coherence to reduce the information required to represent an image. In many communications systems, the communications channel is characterized by a probabilistic model which describes the capacity or fidelity of the channel. The implication is that information is lost or distorted in the channel, and requires concealment on the receiving end. We demonstrate a generative model based transmission scheme to compress human face images in video, which has the advantages of a potentially higher compression ratio, while maintaining robustness to errors and data corruption. This is accomplished by training an offline face model and using the model to reconstruct face images on the receiving end. We propose a sub-component AAM modeling the appearance of sub-facial components individually, and show face reconstruction results under different types of video degradation using a weighted and non-weighted version of the sub-component AAM.

  18. Steady-state plant model to predict hydrogen levels in power plant components

    Science.gov (United States)

    Glatzmaier, Greg C.; Cable, Robert; Newmarker, Marc

    2017-06-01

    The National Renewable Energy Laboratory (NREL) and Acciona Energy North America developed a full-plant steady-state computational model that estimates levels of hydrogen in parabolic trough power plant components. The model estimated dissolved hydrogen concentrations in the circulating heat transfer fluid (HTF), and corresponding partial pressures within each component. Additionally for collector field receivers, the model estimated hydrogen pressure in the receiver annuli. The model was developed to estimate long-term equilibrium hydrogen levels in power plant components, and to predict the benefit of hydrogen mitigation strategies for commercial power plants. Specifically, the model predicted reductions in hydrogen levels within the circulating HTF that result from purging hydrogen from the power plant expansion tanks at a specified target rate. Our model predicted hydrogen partial pressures from 8.3 mbar to 9.6 mbar in the power plant components when no mitigation treatment was employed at the expansion tanks. Hydrogen pressures in the receiver annuli were 8.3 to 8.4 mbar. When hydrogen partial pressure was reduced to 0.001 mbar in the expansion tanks, hydrogen pressures in the receiver annuli fell to a range of 0.001 mbar to 0.02 mbar. When hydrogen partial pressure was reduced to 0.3 mbar in the expansion tanks, hydrogen pressures in the receiver annuli fell to a range of 0.25 mbar to 0.28 mbar. Our results show that controlling hydrogen partial pressure in the expansion tanks allows us to reduce and maintain hydrogen pressures in the receiver annuli to any practical level.

  19. Steady-State Plant Model to Predict Hydroden Levels in Power Plant Components

    Energy Technology Data Exchange (ETDEWEB)

    Glatzmaier, Greg C.; Cable, Robert; Newmarker, Marc

    2017-06-27

    The National Renewable Energy Laboratory (NREL) and Acciona Energy North America developed a full-plant steady-state computational model that estimates levels of hydrogen in parabolic trough power plant components. The model estimated dissolved hydrogen concentrations in the circulating heat transfer fluid (HTF), and corresponding partial pressures within each component. Additionally for collector field receivers, the model estimated hydrogen pressure in the receiver annuli. The model was developed to estimate long-term equilibrium hydrogen levels in power plant components, and to predict the benefit of hydrogen mitigation strategies for commercial power plants. Specifically, the model predicted reductions in hydrogen levels within the circulating HTF that result from purging hydrogen from the power plant expansion tanks at a specified target rate. Our model predicted hydrogen partial pressures from 8.3 mbar to 9.6 mbar in the power plant components when no mitigation treatment was employed at the expansion tanks. Hydrogen pressures in the receiver annuli were 8.3 to 8.4 mbar. When hydrogen partial pressure was reduced to 0.001 mbar in the expansion tanks, hydrogen pressures in the receiver annuli fell to a range of 0.001 mbar to 0.02 mbar. When hydrogen partial pressure was reduced to 0.3 mbar in the expansion tanks, hydrogen pressures in the receiver annuli fell to a range of 0.25 mbar to 0.28 mbar. Our results show that controlling hydrogen partial pressure in the expansion tanks allows us to reduce and maintain hydrogen pressures in the receiver annuli to any practical level.

  20. Fitting a Bivariate Measurement Error Model for Episodically Consumed Dietary Components

    KAUST Repository

    Zhang, Saijuan

    2011-01-06

    There has been great public health interest in estimating usual, i.e., long-term average, intake of episodically consumed dietary components that are not consumed daily by everyone, e.g., fish, red meat and whole grains. Short-term measurements of episodically consumed dietary components have zero-inflated skewed distributions. So-called two-part models have been developed for such data in order to correct for measurement error due to within-person variation and to estimate the distribution of usual intake of the dietary component in the univariate case. However, there is arguably much greater public health interest in the usual intake of an episodically consumed dietary component adjusted for energy (caloric) intake, e.g., ounces of whole grains per 1000 kilo-calories, which reflects usual dietary composition and adjusts for different total amounts of caloric intake. Because of this public health interest, it is important to have models to fit such data, and it is important that the model-fitting methods can be applied to all episodically consumed dietary components.We have recently developed a nonlinear mixed effects model (Kipnis, et al., 2010), and have fit it by maximum likelihood using nonlinear mixed effects programs and methodology (the SAS NLMIXED procedure). Maximum likelihood fitting of such a nonlinear mixed model is generally slow because of 3-dimensional adaptive Gaussian quadrature, and there are times when the programs either fail to converge or converge to models with a singular covariance matrix. For these reasons, we develop a Monte-Carlo (MCMC) computation of fitting this model, which allows for both frequentist and Bayesian inference. There are technical challenges to developing this solution because one of the covariance matrices in the model is patterned. Our main application is to the National Institutes of Health (NIH)-AARP Diet and Health Study, where we illustrate our methods for modeling the energy-adjusted usual intake of fish and whole

  1. Mapping the Two-Component Atomic Fermi Gas to the Nuclear Shell-Model

    DEFF Research Database (Denmark)

    Özen, C.; Zinner, Nikolaj Thomas

    2014-01-01

    of the external potential becomes important. A system of two-species fermionic cold atoms with an attractive zero-range interaction is analogous to a simple model of nucleus in which neutrons and protons interact only through a residual pairing interaction. In this article, we discuss how the problem of a two......-component atomic fermi gas in a tight external trap can be mapped to the nuclear shell model so that readily available many-body techniques in nuclear physics, such as the Shell Model Monte Carlo (SMMC) method, can be directly applied to the study of these systems. We demonstrate an application of the SMMC method...

  2. Mathematical modelling of complex equilibria taking into account experimental data on activities of components

    Energy Technology Data Exchange (ETDEWEB)

    Nikolaeva, L.S.; Evseev, A.M.; Rozen, A.M.; Bobytev, A.P.; Kir' yanov, Yu.A. (Moskovskij Gosudarstvennyj Univ. (USSR))

    1981-09-01

    The extraction systems, the application of which is possible when reprocessing irradiated nuclear fuels are considered. It is shown that the selection of the component activities as the observed properties of the system (responses) provides a possibility to model the equilibria using methods of the regression analysis. The mathematical model of nitric acid extraction with tributyl phosphate is presented. The data on the composition of the complexes in the system studied, obtained by the method of mathematical modelling, are confirmed with the study of the IR spectra of the extracts.

  3. Two-component model of strong Langmuir turbulence - Scalings, spectra, and statistics of Langmuir waves

    Science.gov (United States)

    Robinson, P. A.; Newman, D. L.

    1990-01-01

    A simple two-component model of strong turbulence that makes clear predictions for the scalings, spectra, and statistics of Langmuir waves is developed. Scalings of quantities such as energy density, power input, dissipation power wave collapse, and number density of collapsing objects are investigated in detail and found to agree well with model predictions. The nucleation model of wave-packet formation is strongly supported by the results. Nucleation proceeds with energy flowing from background to localized states even in the absence of a driver. Modulational instabilities play little or no role in maintaining the turbulent state when significant density nonuniformities are present.

  4. Detailed measurements and modelling of thermo active components using a room size test facility

    DEFF Research Database (Denmark)

    Weitzmann, Peter; Svendsen, Svend

    2005-01-01

    This paper describes an investigation of thermo active components based on prefabricated hollow core concrete decks. Recent years have given an increased awareness of the use of thermo active components as an alternative to mechanical cooling systems in office buildings. The investigation covers...... measurements in an office sized test facility with thermo active ceiling and floor as well as modelling of similar conditions in a computer program designed for analysis of building integrated heating and cooling systems. A method for characterizing the cooling capacity of thermo active components is described...... based on measurements of the energy balance of the thermo active deck. A cooling capacity of around 60W/m² at a temperature difference of 10K between room and fluid temperature has been found. It is also shown, that installing a lowered acoustic ceiling covering around 50% of the ceiling surface area...

  5. Deformable known component model-based reconstruction for coronary CT angiography

    Science.gov (United States)

    Zhang, X.; Tilley, S.; Xu, S.; Mathews, A.; McVeigh, E. R.; Stayman, J. W.

    2017-03-01

    Purpose: Atherosclerosis detection remains challenging in coronary CT angiography for patients with cardiac implants. Pacing electrodes of a pacemaker or lead components of a defibrillator can create substantial blooming and streak artifacts in the heart region, severely hindering the visualization of a plaque of interest. We present a novel reconstruction method that incorporates a deformable model for metal leads to eliminate metal artifacts and improve anatomy visualization even near the boundary of the component. Methods: The proposed reconstruction method, referred as STF-dKCR, includes a novel parameterization of the component that integrates deformation, a 3D-2D preregistration process that estimates component shape and position, and a polyenergetic forward model for x-ray propagation through the component where the spectral properties are jointly estimated. The methodology was tested on physical data of a cardiac phantom acquired on a CBCT testbench. The phantom included a simulated vessel, a metal wire emulating a pacing lead, and a small Teflon sphere attached to the vessel wall, mimicking a calcified plaque. The proposed method was also compared to the traditional FBP reconstruction and an interpolation-based metal correction method (FBP-MAR). Results: Metal artifacts presented in standard FBP reconstruction were significantly reduced in both FBP-MAR and STF- dKCR, yet only the STF-dKCR approach significantly improved the visibility of the small Teflon target (within 2 mm of the metal wire). The attenuation of the Teflon bead improved to 0.0481 mm-1 with STF-dKCR from 0.0166 mm-1 with FBP and from 0.0301 mm-1 with FBP-MAR - much closer to the expected 0.0414 mm-1. Conclusion: The proposed method has the potential to improve plaque visualization in coronary CT angiography in the presence of wire-shaped metal components.

  6. The ORC method. Effective modelling of thermal performance of multilayer building components

    Energy Technology Data Exchange (ETDEWEB)

    Akander, Jan

    2000-02-01

    The ORC Method (Optimised RC-networks) provides a means of modelling one- or multidimensional heat transfer in building components, in this context within building simulation environments. The methodology is shown, primarily applied to heat transfer in multilayer building components. For multilayer building components, the analytical thermal performance is known, given layer thickness and material properties. The aim of the ORC Method is to optimise the values of the thermal resistances and heat capacities of an RC-model such as to give model performance a good agreement with the analytical performance, for a wide range of frequencies. The optimisation procedure is made in the frequency domain, where the over-all deviation between model and analytical frequency response, in terms of admittance and dynamic transmittance, is minimised. It is shown that ORC's are effective in terms of accuracy and computational time in comparison to finite difference models when used in building simulations, in this case with IDA/ICE. An ORC configuration of five mass nodes has been found to model building components in Nordic countries well, within the application of thermal comfort and energy requirement simulations. Simple RC-networks, such as the surface heat capacity and the simple R-C-configuration are not appropriate for detailed building simulation. However, these can be used as basis for defining the effective heat capacity of a building component. An approximate method is suggested on how to determine the effective heat capacity without the use of complex numbers. This entity can be calculated on basis of layer thickness and material properties with the help of two time constants. The approximate method can give inaccuracies corresponding to 20%. In-situ measurements have been carried out in an experimental building with the purpose of establishing the effective heat capacity of external building components that are subjected to normal thermal conditions. The auxiliary

  7. Astronomical component estimation (ACE v.1) by time-variant sinusoidal modeling

    Science.gov (United States)

    Sinnesael, Matthias; Zivanovic, Miroslav; De Vleeschouwer, David; Claeys, Philippe; Schoukens, Johan

    2016-09-01

    Accurately deciphering periodic variations in paleoclimate proxy signals is essential for cyclostratigraphy. Classical spectral analysis often relies on methods based on (fast) Fourier transformation. This technique has no unique solution separating variations in amplitude and frequency. This characteristic can make it difficult to correctly interpret a proxy's power spectrum or to accurately evaluate simultaneous changes in amplitude and frequency in evolutionary analyses. This drawback is circumvented by using a polynomial approach to estimate instantaneous amplitude and frequency in orbital components. This approach was proven useful to characterize audio signals (music and speech), which are non-stationary in nature. Paleoclimate proxy signals and audio signals share similar dynamics; the only difference is the frequency relationship between the different components. A harmonic-frequency relationship exists in audio signals, whereas this relation is non-harmonic in paleoclimate signals. However, this difference is irrelevant for the problem of separating simultaneous changes in amplitude and frequency. Using an approach with overlapping analysis frames, the model (Astronomical Component Estimation, version 1: ACE v.1) captures time variations of an orbital component by modulating a stationary sinusoid centered at its mean frequency, with a single polynomial. Hence, the parameters that determine the model are the mean frequency of the orbital component and the polynomial coefficients. The first parameter depends on geologic interpretations, whereas the latter are estimated by means of linear least-squares. As output, the model provides the orbital component waveform, either in the depth or time domain. Uncertainty analyses of the model estimates are performed using Monte Carlo simulations. Furthermore, it allows for a unique decomposition of the signal into its instantaneous amplitude and frequency. Frequency modulation patterns reconstruct changes in

  8. Explicit finite element modelling of the impaction of metal press-fit acetabular components.

    Science.gov (United States)

    Hothi, H S; Busfield, J J C; Shelton, J C

    2011-03-01

    Metal press-fit cups and shells are widely used in hip resurfacing and total hip replacement procedures. These acetabular components are inserted into a reamed acetabula cavity by either impacting their inner polar surface (shells) or outer rim (cups). Two-dimensional explicit dynamics axisymmetric finite element models were developed to simulate these impaction methods. Greater impact velocities were needed to insert the components when the interference fit was increased; a minimum velocity of 2 m/s was required to fully seat a component with a 2 mm interference between the bone and outer diameter. Changing the component material from cobalt-chromium to titanium alloy resulted in a reduction in the number of impacts on the pole to seat it from 14 to nine. Of greatest significance, it was found that locking a rigid cap to the cup or shell rim resulted in up to nine fewer impactions being necessary to seat it than impacting directly on the polar surface or using a cap free from the rim of the component, as is the case with many commercial resurfacing cup impaction devices currently used. This is important to impactor design and could make insertion easier and also reduce acetabula bone damage.

  9. Description of adsorption of hydrophobic organic compounds on sediment using multi-component adsorption model

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A chemical sequential separation procedure for sediment bas been developed for the adsorptive investigation of hydrophobic organic compounds(HOCs) including four fractions: carbonate, hydrous metallic oxide(ferric oxide, manganese oxide and alumina), clay and organic matter. Adsorption isotherms of these hydrophobic solute probes, such as hexachloroethane, lindane and 1,2,4,5-tetrachlorobenzene were measured for model sorbents, model and natural sediment, and the latter of which was pretreated with the simplified sequential separation method. The linear and Langmuir models are applied to correlate the experimental data of humic substance and other model sorbents respectively. Multi-component Adsorptive Model (MCAM) was used to simulate adsorption isotherms of model and natural sediment. The results reveal that( 1 ) the separation efficiencies of carbonate, organic matter, ferric oxide, manganese oxide and alumina are 98. 1 % , 72.5% ,82.6%, 93.5% and 83.3%, respectively; (2) except for removing metallic oxide, the external structure of sediment is not changed greatly after separation; (3) the MCAM correlates the data of adsorption isotherm rather well with the maximal relative deviations of 9.76 % , 6.78 %and 9.53% for hexachloroethane, lindane and 1,2,4,5-tetrachlorobenaze in model sediment, respectively. The MCAM can clearly give expression to the different adsorptive mechanisms for HOCs in organic and inorganic matter, though the experimental data in each component are not very accurate due to the sequential separation efficiency.

  10. Blind Separation of Acoustic Signals Combining SIMO-Model-Based Independent Component Analysis and Binary Masking

    Directory of Open Access Journals (Sweden)

    Hiekata Takashi

    2006-01-01

    Full Text Available A new two-stage blind source separation (BSS method for convolutive mixtures of speech is proposed, in which a single-input multiple-output (SIMO-model-based independent component analysis (ICA and a new SIMO-model-based binary masking are combined. SIMO-model-based ICA enables us to separate the mixed signals, not into monaural source signals but into SIMO-model-based signals from independent sources in their original form at the microphones. Thus, the separated signals of SIMO-model-based ICA can maintain the spatial qualities of each sound source. Owing to this attractive property, our novel SIMO-model-based binary masking can be applied to efficiently remove the residual interference components after SIMO-model-based ICA. The experimental results reveal that the separation performance can be considerably improved by the proposed method compared with that achieved by conventional BSS methods. In addition, the real-time implementation of the proposed BSS is illustrated.

  11. The multi-component model of working memory: explorations in experimental cognitive psychology.

    Science.gov (United States)

    Repovs, G; Baddeley, A

    2006-04-28

    There are a number of ways one can hope to describe and explain cognitive abilities, each of them contributing a unique and valuable perspective. Cognitive psychology tries to develop and test functional accounts of cognitive systems that explain the capacities and properties of cognitive abilities as revealed by empirical data gathered by a range of behavioral experimental paradigms. Much of the research in the cognitive psychology of working memory has been strongly influenced by the multi-component model of working memory [Baddeley AD, Hitch GJ (1974) Working memory. In: Recent advances in learning and motivation, Vol. 8 (Bower GA, ed), pp 47-90. New York: Academic Press; Baddeley AD (1986) Working memory. Oxford, UK: Clarendon Press; Baddeley A. Working memory: Thought and action. Oxford: Oxford University Press, in press]. By expanding the notion of a passive short-term memory to an active system that provides the basis for complex cognitive abilities, the model has opened up numerous questions and new lines of research. In this paper we present the current revision of the multi-component model that encompasses a central executive, two unimodal storage systems: a phonological loop and a visuospatial sketchpad, and a further component, a multimodal store capable of integrating information into unitary episodic representations, termed episodic buffer. We review recent empirical data within experimental cognitive psychology that has shaped the development of the multicomponent model and the understanding of the capacities and properties of working memory. Research based largely on dual-task experimental designs and on neuropsychological evidence has yielded valuable information about the fractionation of working memory into independent stores and processes, the nature of representations in individual stores, the mechanisms of their maintenance and manipulation, the way the components of working memory relate to each other, and the role they play in other

  12. Large-scale Models Reveal the Two-component Mechanics of Striated Muscle

    Directory of Open Access Journals (Sweden)

    Robert Jarosch

    2008-12-01

    Full Text Available This paper provides a comprehensive explanation of striated muscle mechanics and contraction on the basis of filament rotations. Helical proteins, particularly the coiled-coils of tropomyosin, myosin and α-actinin, shorten their H-bonds cooperatively and produce torque and filament rotations when the Coulombic net-charge repulsion of their highly charged side-chains is diminished by interaction with ions. The classical “two-component model” of active muscle differentiated a “contractile component” which stretches the “series elastic component” during force production. The contractile components are the helically shaped thin filaments of muscle that shorten the sarcomeres by clockwise drilling into the myosin cross-bridges with torque decrease (= force-deficit. Muscle stretch means drawing out the thin filament helices off the cross-bridges under passive counterclockwise rotation with torque increase (= stretch activation. Since each thin filament is anchored by four elastic α-actinin Z-filaments (provided with forceregulating sites for Ca2+ binding, the thin filament rotations change the torsional twist of the four Z-filaments as the “series elastic components”. Large scale models simulate the changes of structure and force in the Z-band by the different Z-filament twisting stages A, B, C, D, E, F and G. Stage D corresponds to the isometric state. The basic phenomena of muscle physiology, i. e. latency relaxation, Fenn-effect, the force-velocity relation, the length-tension relation, unexplained energy, shortening heat, the Huxley-Simmons phases, etc. are explained and interpreted with the help of the model experiments.

  13. Evaluation and improvement of the cloud resolving model component of the multi-scale modeling framework

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kuan-Man; Cheng, Anning

    2009-10-01

    Developed, implemented and tested an improved Colorado State University (CSU) SAM (System for Atmospheric Modeling) cloud-resolving model (CRM) with the advanced third-order turbulence closure (IPHOC).

  14. A Modeling Framework to Investigate the Radial Component of the Pushrim Force in Manual Wheelchair Propulsion

    Directory of Open Access Journals (Sweden)

    Ackermann Marko

    2015-01-01

    Full Text Available The ratio of tangential to total pushrim force, the so-called Fraction Effective Force (FEF, has been used to evaluate wheelchair propulsion efficiency based on the fact that only the tangential component of the force on the pushrim contributes to actual wheelchair propulsion. Experimental studies, however, consistently show low FEF values and recent experimental as well as modelling investigations have conclusively shown that a more tangential pushrim force direction can lead to a decrease and not increase in propulsion efficiency. This study aims at quantifying the contributions of active, inertial and gravitational forces to the normal pushrim component. In order to achieve this goal, an inverse dynamics-based framework is proposed to estimate individual contributions to the pushrim forces using a model of the wheelchair-user system. The results show that the radial pushrim force component arise to a great extent due to purely mechanical effects, including inertial and gravitational forces. These results corroborate previous findings according to which radial pushrim force components are not necessarily a result of inefficient propulsion strategies or hand-rim friction requirements. This study proposes a novel framework to quantify the individual contributions of active, inertial and gravitational forces to pushrim forces during wheelchair propulsion.

  15. Principal Component Analysis and Radiative Transfer modelling of Spitzer IRS Spectra of Ultra Luminous Infrared Galaxies

    CERN Document Server

    Hurley, Peter D; Farrah, Duncan; Wang, Lingyu; Efstathiou, Andreas

    2012-01-01

    The mid-infrared spectra of ultraluminous infrared galaxies (ULIRGs) contain a variety of spectral features that can be used as diagnostics to characterise the spectra. However, such diagnostics are biased by our prior prejudices on the origin of the features. Moreover, by using only part of the spectrum they do not utilise the full information content of the spectra. Blind statistical techniques such as principal component analysis (PCA) consider the whole spectrum, find correlated features and separate them out into distinct components. We further investigate the principal components (PCs) of ULIRGs derived in Wang et al.(2011). We quantitatively show that five PCs is optimal for describing the IRS spectra. These five components (PC1-PC5) and the mean spectrum provide a template basis set that reproduces spectra of all z<0.35 ULIRGs within the noise. For comparison, the spectra are also modelled with a combination of radiative transfer models of both starbursts and the dusty torus surrounding active gala...

  16. Modeling Heterogeneous Variance-Covariance Components in Two-Level Models

    Science.gov (United States)

    Leckie, George; French, Robert; Charlton, Chris; Browne, William

    2014-01-01

    Applications of multilevel models to continuous outcomes nearly always assume constant residual variance and constant random effects variances and covariances. However, modeling heterogeneity of variance can prove a useful indicator of model misspecification, and in some educational and behavioral studies, it may even be of direct substantive…

  17. Roadmap for Lean implementation in Indian automotive component manufacturing industry: comparative study of UNIDO Model and ISM Model

    Science.gov (United States)

    Jadhav, J. R.; Mantha, S. S.; Rane, S. B.

    2014-07-01

    The demands for automobiles increased drastically in last two and half decades in India. Many global automobile manufacturers and Tier-1 suppliers have already set up research, development and manufacturing facilities in India. The Indian automotive component industry started implementing Lean practices to fulfill the demand of these customers. United Nations Industrial Development Organization (UNIDO) has taken proactive approach in association with Automotive Component Manufacturers Association of India (ACMA) and the Government of India to assist Indian SMEs in various clusters since 1999 to make them globally competitive. The primary objectives of this research are to study the UNIDO-ACMA Model as well as ISM Model of Lean implementation and validate the ISM Model by comparing with UNIDO-ACMA Model. It also aims at presenting a roadmap for Lean implementation in Indian automotive component industry. This paper is based on secondary data which include the research articles, web articles, doctoral thesis, survey reports and books on automotive industry in the field of Lean, JIT and ISM. ISM Model for Lean practice bundles was developed by authors in consultation with Lean practitioners. The UNIDO-ACMA Model has six stages whereas ISM Model has eight phases for Lean implementation. The ISM-based Lean implementation model is validated through high degree of similarity with UNIDO-ACMA Model. The major contribution of this paper is the proposed ISM Model for sustainable Lean implementation. The ISM-based Lean implementation framework presents greater insight of implementation process at more microlevel as compared to UNIDO-ACMA Model.

  18. Capable of Suicide: A Functional Model of the Acquired Capability Component of the Interpersonal-Psychological Theory of Suicide

    Science.gov (United States)

    Smith, Phillip N.; Cukrowicz, Kelly C.

    2010-01-01

    A functional model of the acquired capability for suicide, a component of Joiner's (2005) Interpersonal-Psychological Theory of Suicide, is presented. A component of Joiner's (2005) Interpersonal-Psychological Theory of Suicide a functional model of the acquired capability for suicide is presented. The model integrates the points discussed by…

  19. Coarse-grained component concurrency in Earth system modeling: parallelizing atmospheric radiative transfer in the GFDL AM3 model using the Flexible Modeling System coupling framework

    Science.gov (United States)

    Balaji, V.; Benson, Rusty; Wyman, Bruce; Held, Isaac

    2016-10-01

    Climate models represent a large variety of processes on a variety of timescales and space scales, a canonical example of multi-physics multi-scale modeling. Current hardware trends, such as Graphical Processing Units (GPUs) and Many Integrated Core (MIC) chips, are based on, at best, marginal increases in clock speed, coupled with vast increases in concurrency, particularly at the fine grain. Multi-physics codes face particular challenges in achieving fine-grained concurrency, as different physics and dynamics components have different computational profiles, and universal solutions are hard to come by. We propose here one approach for multi-physics codes. These codes are typically structured as components interacting via software frameworks. The component structure of a typical Earth system model consists of a hierarchical and recursive tree of components, each representing a different climate process or dynamical system. This recursive structure generally encompasses a modest level of concurrency at the highest level (e.g., atmosphere and ocean on different processor sets) with serial organization underneath. We propose to extend concurrency much further by running more and more lower- and higher-level components in parallel with each other. Each component can further be parallelized on the fine grain, potentially offering a major increase in the scalability of Earth system models. We present here first results from this approach, called coarse-grained component concurrency, or CCC. Within the Geophysical Fluid Dynamics Laboratory (GFDL) Flexible Modeling System (FMS), the atmospheric radiative transfer component has been configured to run in parallel with a composite component consisting of every other atmospheric component, including the atmospheric dynamics and all other atmospheric physics components. We will explore the algorithmic challenges involved in such an approach, and present results from such simulations. Plans to achieve even greater levels of

  20. A blind separation method of overlapped multi-components based on time varying AR model

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A method utilizing single channel recordings to blindly separate the multicomponents overlapped in time and frequency domains is proposed in this paper. Based on the time varying AR model, the instantaneous frequency and amplitude of each signal component are estimated respectively, thus the signal component separation is achieved. By using prolate spheroidal sequence as basis functions to expand the time varying parameters of the AR model, the method turns the problem of linear time varying parameters estimation to a linear time invariant parameter estimation problem, then the parameters are estimated by a recursive algorithm. The computation of this method is simple, and no prior knowledge of the signals is needed. Simulation results demonstrate validity and excellent performance of this method.

  1. Improving the accuracy: volatility modeling and forecasting using high-frequency data and the variational component

    Directory of Open Access Journals (Sweden)

    Manish Kumar

    2010-06-01

    Full Text Available In this study, we predict the daily volatility of the S&P CNX NIFTY market index of India using the basic ‘heterogeneous autoregressive’ (HAR and its variant. In doing so, we estimated several HAR and Log form of HAR models using different regressor. The different regressors were obtained by extracting the jump and continuous component and the threshold jump and continuous component from the realized volatility. We also tried to investigate whether dividing volatility into simple and threshold jumps and continuous variation yields a substantial improvement in volatility forecasting or not. The results provide the evidence that inclusion of realized bipower variance in the HAR models helps in predicting future volatility.

  2. Cross-validation of component models: a critical look at current methods.

    Science.gov (United States)

    Bro, R; Kjeldahl, K; Smilde, A K; Kiers, H A L

    2008-03-01

    In regression, cross-validation is an effective and popular approach that is used to decide, for example, the number of underlying features, and to estimate the average prediction error. The basic principle of cross-validation is to leave out part of the data, build a model, and then predict the left-out samples. While such an approach can also be envisioned for component models such as principal component analysis (PCA), most current implementations do not comply with the essential requirement that the predictions should be independent of the entity being predicted. Further, these methods have not been properly reviewed in the literature. In this paper, we review the most commonly used generic PCA cross-validation schemes and assess how well they work in various scenarios.

  3. Roughing It Up: Including Jump Components in the Measurement, Modeling and Forecasting of Return Volatility

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Andersen, Torben G.; Diebold, Francis X.

    -Nielsen and Shephard (2004a, 2005) for related bi-power variation measures, the present paper provides a practical and robust framework for non-parametrically measuring the jump component in asset return volatility. In an application to the DM/$ exchange rate, the S&P500 market index, and the 30-year U.S. Treasury......A rapidly growing literature has documented important improvements in financial return volatility measurement and forecasting via use of realized variation measures constructed from high-frequency returns coupled with simple modeling procedures. Building on recent theoretical results in Barndorff...... but sophisticated volatility forecasting model, we find that almost all of the predictability in daily, weekly, and monthly return volatilities comes from the non-jump component. Our results thus set the stage for a number of interesting future econometric developments and important financial applications...

  4. Partitioning internal variability and model uncertainty components in a multireplicate multimodel ensemble of hydrometeorological future projections

    Science.gov (United States)

    Hingray, Benoit; Saïd, Mériem; Lafaysse, Matthieu; Gailhlard, Joël; Mezghani, Abdelkader

    2014-05-01

    A simple and robust framework was proposed by Hingray and Mériem (2013) for the partitioning of the different components of internal variability and model uncertainty in a multireplicate multimodel ensemble (MRMME) of climate projections obtained for a suite of statistical downscaling models (SDMs) and global climate models (GCMs). It is based on the quasi-ergodic assumption for transient climate simulations. Model uncertainty components are estimated from the noise-free signals of each modeling chain using a two-way ANOVA framework. The residuals from the noise-free signal are used to estimate the large and small scale internal variability (IV) components associated with each considered GCM/SDM configuration. This framework makes it possible to take into account all runs and replicates available from any climate ensemble of opportunity. This quasi-ergodic ANOVA framework was applied to the MRMME of hydrometeorological simulations produced for the Upper Durance River basin (French Alps) over the 1860-2100 period within the RIWER2030 research project (http://www.lthe.fr/RIWER2030/). The different uncertainty sources were quantified as a function of lead time for projected changes in temperature, precipitation, evaporation losses, snow cover and discharges (Lafaysse et al., 2013). For temperature, GCM uncertainty prevails and, as opposed to IV, SDM uncertainty is non-negligible. Significant warming and in turn significant changes are predicted for evaporation, snow cover and seasonality of discharges. For precipitation, GCM and SDM uncertainty components are of the same order. Despite high model uncertainty, the non-zero climate change response of simulation chains is significant and annual precipitation is expected to decrease. However, high values are obtained for the large and small scale components of IV, inherited respectively from the GCMs and the different replicates of a given SDM. The same applies for annual discharge. The uncertainty in values that could

  5. Mice with human immune system components as in vivo models for infections with human pathogens.

    Science.gov (United States)

    Rämer, Patrick C; Chijioke, Obinna; Meixlsperger, Sonja; Leung, Carol S; Münz, Christian

    2011-03-01

    Many pathogens relevant to human disease do not infect other animal species. Therefore, animal models that reconstitute or harbor human tissues are explored as hosts for these. In this review, we will summarize recent advances to utilize mice with human immune system components, reconstituted from hematopoietic progenitor cells in vivo. Such mice can be used to study human pathogens that replicate in leukocytes. In addition to studying the replication of these pathogens, the reconstituted human immune system components can also be analyzed for initiating immune responses and control against these infections. Moreover, these new animal models of human infectious disease should replicate the reactivity of the human immune system to vaccine candidates and, especially, the adjuvants contained in them, more faithfully.

  6. Error Propagation in Equations for Geochemical Modeling of Radiogenic Isotopes in Two-Component Mixing

    Indian Academy of Sciences (India)

    Surendra P Verma

    2000-03-01

    This paper presents error propagation equations for modeling of radiogenic isotopes during mixing of two components or end-members. These equations can be used to estimate errors on an isotopic ratio in the mixture of two components, as a function of the analytical errors or the total errors of geological field sampling and analytical errors. Two typical cases (``Small errors'' and ``Large errors'') are illustrated for mixing of Sr isotopes. Similar examples can be formulated for the other radiogenic isotopic ratios. Actual isotopic data for sediment and basalt samples from the Cocos plate are also included to further illustrate the use of these equations. The isotopic compositions of the predicted mixtures can be used to constrain the origin of magmas in the central part of the Mexican Volcanic Belt. These examples show the need of high quality experimental data for them to be useful in geochemical modeling of magmatic processes.

  7. A two-component Frenkel-Kontorowa model for surface alloy formation

    CERN Document Server

    Daruka, I

    2003-01-01

    It has been shown by recent experiments that bulk immiscible metals (e.g. Ag/Cu, Ag/Co and Au/Ni) can form binary alloys on certain surfaces where the substrate mediates the elastic misfits between the two components, thus relieving the elastic strain in the overlayer. These novel surface alloys exhibit a rich phase structure. We formulate a two-component Frenkel-Kontorova model in one dimension to study surface alloy formation. This model can naturally incorporate dislocation formation that plays a crucial role in determining the actual structure of the system. Using energy minimization calculations we provide a phase diagram in terms of average alloy composition and the energy of mixing. Monte Carlo simulations were also performed to study the structure and interaction of the emerging dislocations.

  8. Pinning Properties of Commercial Nb-Ti Wires Described by a 2-Components Model

    CERN Document Server

    Muzzi, L; Zignani, Chiarasole Fiamozzi; De Marzi, Gianluca; Muzzi, Luigi; Dominguez, Cesar Octavio; Bottura, Luca; Napolitano, Mathieu; Viola, Rosario; Affinito, Luigi; della Corte, Antonio; Le Naour, Sandrine

    2010-01-01

    We report on the magnetic and transport characterization of different NbTi commercial strands, carried out at variable temperature and magnetic field. From the critical current densities extracted from transport measurements and magnetization cycles we were able to calculate the normalized bulk pinning forces. The curves show good temperature scaling throughout the explored temperature range, and the reduced pinning force can be described by a simple two-components model system. The extension of the 2-components description of the pinning force to an expression for the critical current density gives a very good agreement with experimental measurements over the whole explored B, T range. The model works for all investigated samples, which are different in size, Cu:nonCu ratios, filament diameters and layouts. These results suggest that pinning mechanisms in conventional NbTi strands should be revised, since Nb-Ti composition gradients and grain boundaries seems to play a not negligible role.

  9. High Cost/High Risk Components to Chalcogenide Molded Lens Model: Molding Preforms and Mold Technology

    Energy Technology Data Exchange (ETDEWEB)

    Bernacki, Bruce E.

    2012-10-05

    This brief report contains a critique of two key components of FiveFocal's cost model for glass compression molding of chalcogenide lenses for infrared applications. Molding preforms and mold technology have the greatest influence on the ultimate cost of the product and help determine the volumes needed to select glass molding over conventional single-point diamond turning or grinding and polishing. This brief report highlights key areas of both technologies with recommendations for further study.

  10. Numerical Modelling of Multi-Phase Multi-Component Reactive Transport in the Earth's interior

    Science.gov (United States)

    Oliveira, Beñat; Afonso, Juan Carlos; Zlotnik, Sergio; Tilhac, Romain

    2017-04-01

    We present a conceptual and numerical approach to model processes in the Earth's interior that involve multiple phases that simultaneously interact thermally, mechanically and chemically. The approach is truly multiphase in the sense that each dynamic phase is explicitly modelled with an individual set of mass, momentum, energy and chemical mass balance equations coupled via interfacial interaction terms. It is also truly multi-component in the sense that the compositions of the system and its constituent thermodynamic phases are expressed by a full set of fundamental chemical components (e.g. SiO_2, Al_2O_3, MgO, etc) rather than proxies. In contrast to previous approaches these chemical components evolve, react with, and partition into, different phases with different physical properties according to an internally-consistent thermodynamic model. This enables a thermodynamically-consistent coupling of the governing set of balance equations. Interfacial processes such as surface tensions and/or surface energy contributions to the dynamics and energetics of the system are also taken into account. The model presented here describes the evolution of systems governed by Multi-Phase Multi-Component Reactive Transport (MPMCRT) based on Ensemble Averaging and Classical Irreversible Thermodynamics principles. This novel approach provides a flexible platform to study the dynamics and non-linear feedbacks occurring within various natural systems at different scales. This notably includes major- and trace-element transport, diffusion-controlled trace-element re-equilibration or rheological changes associated with melt generation and migration in the Earth's mantle.

  11. Mice with human immune system components as in vivo models for infections with human pathogens

    OpenAIRE

    Rämer, P C; Chijioke, O; Meixlsperger, S; Leung, C S; Münz, C.

    2011-01-01

    Many pathogens relevant to human disease do not infect other animal species. Therefore, animal models that reconstitute or harbour human tissues are explored as hosts for these. In this review, we will summarize recent advances to utilize mice with human immune system components, reconstituted from hematopoietic progenitor cells in vivo. Such mice can be used to study human pathogens that replicate in leucocytes. In addition to studying the replication of these pathogens, the reconstituted hu...

  12. Experiments and Modeling of Multi-Component Fuel Behavior in Combustion

    Science.gov (United States)

    1984-05-01

    heteroatom components. Such models will be necessary input to the large computer codes which calculate the characteristics of two phase reacting flows...methane -nd acetylene accompanied by soot formation. The trends are similar for the two fuels except that JP-4 produces more methane than JP-7. Both fuels...fuels vii1 be increasingly important as the sources shift to heavier petroleum , oil shale, tar sands and coal derived fuels. The combustion of such

  13. A Component-Based Conference Control Model and Implementation for Loosely Coupled Sessions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Conference control is a very important core part to compose a complete Internet multimedia conference system and has been a hot research area over the years, but there are currently no widely accepted robust and scalable solutions and standards. This paper proposes a component-based conference control model for loosely coupled sessions in which media applications can collaborate with a Session Controller(SC) to provide the conference control. A SC prototype has been built.

  14. A probabilisitic based failure model for components fabricated from anisotropic graphite

    Science.gov (United States)

    Xiao, Chengfeng

    The nuclear moderator for high temperature nuclear reactors are fabricated from graphite. During reactor operations graphite components are subjected to complex stress states arising from structural loads, thermal gradients, neutron irradiation damage, and seismic events. Graphite is a quasi-brittle material. Two aspects of nuclear grade graphite, i.e., material anisotropy and different behavior in tension and compression, are explicitly accounted for in this effort. Fracture mechanic methods are useful for metal alloys, but they are problematic for anisotropic materials with a microstructure that makes it difficult to identify a "critical" flaw. In fact cracking in a graphite core component does not necessarily result in the loss of integrity of a nuclear graphite core assembly. A phenomenological failure criterion that does not rely on flaw detection has been derived that accounts for the material behaviors mentioned. The probability of failure of components fabricated from graphite is governed by the scatter in strength. The design protocols being proposed by international code agencies recognize that design and analysis of reactor core components must be based upon probabilistic principles. The reliability models proposed herein for isotropic graphite and graphite that can be characterized as being transversely isotropic are another set of design tools for the next generation very high temperature reactors (VHTR) as well as molten salt reactors. The work begins with a review of phenomenologically based deterministic failure criteria. A number of this genre of failure models are compared with recent multiaxial nuclear grade failure data. Aspects in each are shown to be lacking. The basic behavior of different failure strengths in tension and compression is exhibited by failure models derived for concrete, but attempts to extend these concrete models to anisotropy were unsuccessful. The phenomenological models are directly dependent on stress invariants. A set of

  15. Modeling Stress Strain Relationships and Predicting Failure Probabilities For Graphite Core Components

    Energy Technology Data Exchange (ETDEWEB)

    Duffy, Stephen [Cleveland State Univ., Cleveland, OH (United States)

    2013-09-09

    This project will implement inelastic constitutive models that will yield the requisite stress-strain information necessary for graphite component design. Accurate knowledge of stress states (both elastic and inelastic) is required to assess how close a nuclear core component is to failure. Strain states are needed to assess deformations in order to ascertain serviceability issues relating to failure, e.g., whether too much shrinkage has taken place for the core to function properly. Failure probabilities, as opposed to safety factors, are required in order to capture the bariability in failure strength in tensile regimes. The current stress state is used to predict the probability of failure. Stochastic failure models will be developed that can accommodate possible material anisotropy. This work will also model material damage (i.e., degradation of mechanical properties) due to radiation exposure. The team will design tools for components fabricated from nuclear graphite. These tools must readily interact with finite element software--in particular, COMSOL, the software algorithm currently being utilized by the Idaho National Laboratory. For the eleastic response of graphite, the team will adopt anisotropic stress-strain relationships available in COMSO. Data from the literature will be utilized to characterize the appropriate elastic material constants.

  16. Models and frameworks: a synergistic association for developing component-based applications.

    Science.gov (United States)

    Alonso, Diego; Sánchez-Ledesma, Francisco; Sánchez, Pedro; Pastor, Juan A; Álvarez, Bárbara

    2014-01-01

    The use of frameworks and components has been shown to be effective in improving software productivity and quality. However, the results in terms of reuse and standardization show a dearth of portability either of designs or of component-based implementations. This paper, which is based on the model driven software development paradigm, presents an approach that separates the description of component-based applications from their possible implementations for different platforms. This separation is supported by automatic integration of the code obtained from the input models into frameworks implemented using object-oriented technology. Thus, the approach combines the benefits of modeling applications from a higher level of abstraction than objects, with the higher levels of code reuse provided by frameworks. In order to illustrate the benefits of the proposed approach, two representative case studies that use both an existing framework and an ad hoc framework, are described. Finally, our approach is compared with other alternatives in terms of the cost of software development.

  17. Apoptosis is not an invariable component of in vitro models of cortical cerebral ischaemia

    Institute of Scientific and Technical Information of China (English)

    Paul Alexander JONES; Gillian Ruth MAY; Joyce Ann MCLUCKIE; Akinori IWASHITA; John SHARKEY

    2004-01-01

    Characterising the mechanisms of cell death following focal cerebral ischaemia has been hampered by a lack of an in vitro assay emulating both the apoptotic and necrotic features observed in vivo. The present study systematically characterised oxygen-glucose-deprivation (OGD) in primary rat cortical neurones to establish a reproducible model with components of both cell-death endpoints. OGD induced a time-dependent reduction in cell viability, with 80% cell death occurring 24 h after 3 h exposure to 0% O2 and 0.5 mM glucose. Indicative of a necrotic component to OGDinduced cell death, N-methyl-D-aspartate (NMDA) receptor inhibition with MK-801 attenuated neuronal loss by 60%.The lack of protection by the caspase inhibitors DEVD-CHO and z-VAD-fmk suggested that under these conditions neurones did not die by an apoptotic mechanism. Moderating the severity of the insult by decreasing OGD exposure to 60 min did not reduce the amount of necrosis, but did induce a small degree of apoptosis (a slight reduction in cell death was observed in the presence of 10 μtM DEVD-CHO). In separate experiments purported to enhance the apoptotic component, cells were gradually deprived of O2, exposed to 4% O2 (as opposed to 0%) during the OGD period, or maintained in serum-containing media throughout. While NMDA receptor antagonism significantly reduced cortical cell death under all conditions, a caspase-inhibitor sensitive component of cell death was not uncovered. These studies suggest that OGD of cultured cortical cells models the excitotoxic, but not the apoptotic component of cell death observed in vivo.

  18. Mind the gaps: a state-space model for analysing the dynamics of North Sea herring spawning components

    DEFF Research Database (Denmark)

    Payne, Mark

    2010-01-01

    , the sum of the fitted abundance indices across all components proves an excellent proxy for the biomass of the total stock, even though the model utilizes information at the individual-component level. The Orkney–Shetland component appears to have recovered faster from historic depletion events than...

  19. 理想的构件模型与性能分析%Ideal Component Model and Capacity Analysis

    Institute of Scientific and Technical Information of China (English)

    王斌君; 王靖亚; 郝克刚

    2001-01-01

    After analysing the problem of Object-Oriented technology, advantages and disadvantages of three typical component technology are appraised. According to software architecture philosophy ,an ideal component model is given,and the legacy and dynamic maintenance of the component technology is covered.

  20. AWRA-G: A continental scale groundwater component linked to a land surface water balance model

    Science.gov (United States)

    Joehnk, Klaus; Crosbie, Russell; Peeters, Luk; Doble, Rebecca

    2013-04-01

    The Australian Water Resources Assessment (AWRA) system is a combination of models, data sources and analysis techniques that together will describe the water balance of Australia's landscapes, rivers and groundwater systems. It is a grid based water balance model that has lumped representation of the water balance of the soil, groundwater and surface water stores for each cell. The purpose of AWRA is to operationally provide up to date, credible, comprehensive, and accurate information about the history, present state and future trajectory of the water balance across Australia with sufficient spatial and temporal detail and enable water resources management for undertaking annual water resource assessments and national water accounts. AWRA is developed to link three major components: a landscape water balance model (AWRA-L), a river routing model (AWRA-R), and a groundwater component model (AWRA-G). These three component models combined are expected to be able to model the fluxes and stores of water throughout the landscape. The groundwater component (AWRA-G) addresses an improved representation of groundwater in the AWRA system to describe basic aquifer dynamics and groundwater-surface water processes. While most continental scale land surface models do not have the capacity to allow water to flow between cells and thus ignore this element of the water balance, AWRA-G does account for lateral flows. In general, AWRA-G provides estimates of groundwater fluxes that are not incorporated into either AWRA-L and its modifications to in-cell soil and groundwater processes, or AWRA-R. The processes integrated into AWRA-G thus are lateral groundwater flow between cells in regional and intermediate groundwater flow systems, groundwater discharge to the ocean, groundwater extraction and infiltration, river losses to groundwater, recharge from overbank flooding, and interactions between deep confined systems and surficial groundwater systems. Basis of AWRA-G is a good

  1. Coupled model of composite synthesis allowing the melting of one of the components

    Science.gov (United States)

    Chumakov, Yurii A.; Knyazeva, Anna G.

    2016-11-01

    A model of initiation of the reaction in the flat layer under external heating and various loading was proposed and numerically investigated. Different types of mechanical loading such as uniaxial loading, compression and pure shear were considered. The estimation of stressed-deformed state of reaction system with consumable component and reaction product is based on the model of Maxwell's viscoelastic body. The influence of the coupling between thermal and mechanical processes on temperature, stress and strain fields was investigated. The phenomenon of thermal explosion caused by the acceleration of the reaction by additional thermal flux due to viscous dissipation was discovered.

  2. Density Fluctuations in the Yukawa One Component Plasma: An accurate model for the dynamical structure factor

    CERN Document Server

    Mithen, James P; Crowley, Basil J B; Gregori, Gianluca

    2011-01-01

    Using numerical simulations, we investigate the equilibrium dynamics of a single component fluid with Yukawa interaction potential. We show that, for a wide range of densities and temperatures, the dynamics of the system are in striking agreement with a simple model of generalized hydrodynamics. Since the Yukawa potential can describe the ion-ion interactions in a plasma, the model has significant applicability for both analyzing and interpreting the results of x-ray scattering data from high power lasers and fourth generation light sources.

  3. Choosing components in the additive main effect and multiplicative interaction (AMMI models

    Directory of Open Access Journals (Sweden)

    Dias Carlos Tadeu dos Santos

    2006-01-01

    Full Text Available The additive main effect and multiplicative interaction (AMMI models allows analysts to detect interactions between rows and columns in a two-way table. However, there are many methods proposed in the literature to determine the number of multiplicative components to include in the AMMI model. These methods typically give different results for any particular data set, so the user needs some guidance as to which methods to use. In this paper we compare four commonly used methods using simulated data based on real experiments, and provide some general recommendations.

  4. Predicting adenocarcinoma recurrence using computational texture models of nodule components in lung CT

    Energy Technology Data Exchange (ETDEWEB)

    Depeursinge, Adrien, E-mail: adrien.depeursinge@hevs.ch [Department of Radiology, Stanford University School of Medicine, Stanford, California 94305 and Business Information Systems, University of Applied Sciences Western Switzerland (HES-SO), Sierre 3960 (Switzerland); Yanagawa, Masahiro [Department of Radiology, Stanford University School of Medicine, Stanford, California 94305 and Department of Radiology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871 (Japan); Leung, Ann N.; Rubin, Daniel L. [Department of Radiology, Stanford University School of Medicine, Stanford, California 94305 (United States)

    2015-04-15

    Purpose: To investigate the importance of presurgical computed tomography (CT) intensity and texture information from ground-glass opacities (GGO) and solid nodule components for the prediction of adenocarcinoma recurrence. Methods: For this study, 101 patients with surgically resected stage I adenocarcinoma were selected. During the follow-up period, 17 patients had disease recurrence with six associated cancer-related deaths. GGO and solid tumor components were delineated on presurgical CT scans by a radiologist. Computational texture models of GGO and solid regions were built using linear combinations of steerable Riesz wavelets learned with linear support vector machines (SVMs). Unlike other traditional texture attributes, the proposed texture models are designed to encode local image scales and directions that are specific to GGO and solid tissue. The responses of the locally steered models were used as texture attributes and compared to the responses of unaligned Riesz wavelets. The texture attributes were combined with CT intensities to predict tumor recurrence and patient hazard according to disease-free survival (DFS) time. Two families of predictive models were compared: LASSO and SVMs, and their survival counterparts: Cox-LASSO and survival SVMs. Results: The best-performing predictive model of patient hazard was associated with a concordance index (C-index) of 0.81 ± 0.02 and was based on the combination of the steered models and CT intensities with survival SVMs. The same feature group and the LASSO model yielded the highest area under the receiver operating characteristic curve (AUC) of 0.8 ± 0.01 for predicting tumor recurrence, although no statistically significant difference was found when compared to using intensity features solely. For all models, the performance was found to be significantly higher when image attributes were based on the solid components solely versus using the entire tumors (p < 3.08 × 10{sup −5}). Conclusions: This study

  5. A study of key features of random atmospheric disturbance models for the approach flight phase

    Science.gov (United States)

    Heffley, R. K.

    1977-01-01

    An analysis and brief simulator experiment were performed to identify and classify important features of random turbulence for the landing approach flight phase. The analysis of various wind models was carried out within the context of the longitudinal closed-loop pilot/vehicle system. The analysis demonstrated the relative importance of atmospheric disturbance scale lengths, horizontal versus vertical gust components, decreasing altitude, and spectral forms of disturbances versus the pilot/vehicle system. Among certain competing wind models, the analysis predicted no significant difference in pilot performance. This was confirmed by a moving base simulator experiment which evaluated the two most extreme models. A number of conclusions were reached: attitude constrained equations do provide a simple but effective approach to describing the closed-loop pilot/vehicle. At low altitudes the horizontal gust component dominates pilot/vehicle performance.

  6. High-resolution spatial patterns of Soil Organic Carbon content derived from low-altitude aerial multi-band imagery on the Broadbalk Wheat Experiment at Rothamsted,UK

    Science.gov (United States)

    Aldana Jague, Emilien; Goulding, Keith; Heckrath, Goswin; Macdonald, Andy; Poulton, Paul; Stevens, Antoine; Van Wesemael, Bas; Van Oost, Kristof

    2014-05-01

    Soil organic C (SOC) contents in arable landscapes change as a function of management, climate and topography (Johnston et al, 2009). Traditional methods to measure soil C stocks are labour intensive, time consuming and expensive. Consequently, there is a need for developing low-cost methods for monitoring SOC contents in agricultural soils. Remote sensing methods based on multi-spectral images may help map SOC variation in surface soils. Recently, the costs of both Unmanned Aerial Vehicles (UAVs) and multi-spectral cameras have dropped dramatically, opening up the possibility for more widespread use of these tools for SOC mapping. Long-term field experiments with distinct SOC contents in adjacent plots, provide a very useful resource for systematically testing remote sensing approaches for measuring SOC. This study focusses on the Broadbalk Wheat Experiment at Rothamsted (UK). The Broadbalk experiment started in 1843. It is widely acknowledged to be the oldest continuing agronomic field experiment in the world. The initial aim of the experiment was to test the effects of different organic manures and inorganic fertilizers on the yield of winter wheat. The experiment initially contained 18 strips, each about 320m long and 6m wide, separated by paths of 1.5-2.5m wide. The strips were subsequently divided into ten sections (>180 plots) to test the effects of other factors (crop rotation, herbicides, pesticides etc.). The different amounts and combinations of mineral fertilisers (N,P,K,Na & Mg) and Farmyard Manure (FYM) applied to these plots for over 160 years has resulted in very different SOC contents in adjacent plots, ranging between 0.8% and 3.5%. In addition to large inter-plot variability in SOC there is evidence of within-plot trends related to the use of discard areas between plots and movement of soil as a result of ploughing. The objectives of this study are (i) to test whether low-altitude multi-band imagery can be used to accurately predict spatial

  7. Accurate neural network-based modeling for RF MEMS component synthesizing

    Science.gov (United States)

    Mohamed, Firas; Affour, Bachar

    2004-01-01

    Contrary to traditional analysis flows as expensive FEM simulation tools or inaccurate electrical models extractors, we developed MemsCompiler that implements a new real synthesis approach for RF MEMS. The new flow starts from system designer requirements and generates, in a one-click operation, a ready-to-fabricate layout (GDSII) and a passive fitted equivalent Spice circuit. Concerning the circuit, physical considerations give us an equivalent schematic in which circuit parameters values must be adjusted to fit the required performances. As to the GDSII, which constitutes the main contribution of this work, Design Of Experiment technique, used in the first version of the synthesizer, gave about 11% of dispersion and found to be unsatisfactory in some cases. A more accurate modeling was indispensable. Thus, we developed a neural networks-based modeling for circular inductors, which are considered by designers among the most stubborn components. This new modeling has shown to be very accurate: MemsCompiler produced about 3% of dispersion compared to the equivalent circuit and about 6% of dispersion for generated geometries. This modeling is flexible and could be rapidly generalized to other components.

  8. A curved multi-component aerosol hygroscopicity model framework: Part 1 – Inorganic compounds

    Directory of Open Access Journals (Sweden)

    D. O. Topping

    2005-01-01

    Full Text Available A thermodynamic modelling framework to predict the equilibrium behaviour of mixed inorganic salt aerosols is developed, and then coupled with a technique for finding a solution to the Kohler equation in order to create a diameter dependent hygroscopic aerosol model (Aerosol Diameter Dependent Equilibrium Model – ADDEM. The model described here provides a robust and accurate inorganic basis using a mole fraction based activity coefficient model and adjusted energies of formation for treating solid precipitation. The model framework can accommodate organic components, though this added complexity is considered in a companion paper, this paper describes the development of the modelling architecture to be used and predictions of an inorganic model alone. The modelling framework has been developed to flexibly use a combination of mixing rules and other potentially more accurate techniques where available to calculate the water content. Comparisons with other state-of-the-art general equilibrium models and experimental data are presented and show excellent agreement. The Kelvin effect can be considered in this scheme using a variety of surface tension models. Comparison of predicted diameter dependent phenomena, such as the increased relative humidity for onset of deliquescence with decreasing diameter, with another diameter dependent model is very good despite the different approach used. The model is subject to various sensitivities. For the inorganic systems studied here, the model is sensitive to choice of surface tension scheme used, which decreases for larger aerosol. Large sensitivities are found for the value of dry density used. It is thus likely that the history of the aerosol studied in a hygroscopic tandem differential mobility analyser (HTDMA, specifically the nature of the drying process that will influence the final crystalline form, will create systematic uncertainties upon comparisons with theoretical predictions. However, the

  9. A curved multi-component aerosol hygroscopicity model framework: 1 – Inorganics

    Directory of Open Access Journals (Sweden)

    H. Coe

    2004-12-01

    Full Text Available A thermodynamic modelling framework to predict the equilibrium behaviour of mixed inorganic salt aerosols is developed, and then coupled with a technique for finding a solution to the Köhler equation in order to create a diameter dependent hygroscopic aerosol model (Aerosol Diameter Dependent Equilibrium Model – ADDEM. The model described here provides a robust and accurate inorganic basis using a mole fraction based activity coefficient model and adjusted energies of formation for treating solid precipitation. The model framework can accommodate organic components, though this added complexity is considered in a companion paper, whereas this paper describes the development of the modelling architecture to be used and predictions of an inorganic model alone. The modelling framework has been developed to flexibly use a combination of mixing rules and other potentially more accurate techniques where available to calculate the water content. Comparisons with other state-of-the-art general equilibrium models and experimental data are presented and show excellent agreement. The Kelvin effect can be considered in this scheme using a variety of surface tension models. Comparison of predicted diameter dependent phenomena, such as the increased relative humidity for onset of deliquescence with decreasing diameter, with another diameter dependent model is very good despite the different approach used. The model is subject to various sensitivities. For the inorganic systems studied here, the model is sensitive to choice of surface tension scheme used, which decreases for larger aerosol. Large sensitivities are found for the value of dry density used. It is thus likely that the history of the aerosol studied in a hygroscopic tandem differential mobility analyser (HTDMA, specifically the nature of the drying process that will influence the final crystalline form, will create systematic uncertainties upon comparisons with theoretical predictions. However

  10. Potential for monitoring soil erosion features and soil erosion modeling components from remotely sensed data

    Science.gov (United States)

    Langran, K. J.

    1983-01-01

    Accurate estimates of soil erosion and its effects on soil productivity are essential in agricultural decision making and planning from the field scale to the national level. Erosion models have been primarily developed for designing erosion control systems, predicting sediment yield for reservoir design, predicting sediment transport, and simulating water quality. New models proposed are more comprehensive in that the necessary components (hydrology, erosion-sedimentation, nutrient cycling, tillage, etc.) are linked in a model appropriate for studying the erosion-productivity problem. Recent developments in remote sensing systems, such as Landsat Thematic Mapper, Shuttle Imaging Radar (SIR-B), etc., can contribute significantly to the future development and operational use of these models.

  11. Strong Ground Motion in the 2011 Tohoku Earthquake: a 1Directional - 3Component Modeling

    CERN Document Server

    D'Avila, Maria Paola Santisi; Lenti, Luca

    2013-01-01

    Local wave amplification due to strong seismic motions in surficial multilayered soil is influenced by several parameters such as the wavefield polarization and the dynamic properties and impedance contrast between soil layers. The present research aims at investigating seismic motion amplification in the 2011 Tohoku earthquake through a one-directional three-component (1D-3C) wave propagation model. A 3D nonlinear constitutive relation for dry soils under cyclic loading is implemented in a quadratic line finite element model. The soil rheology is modeled by mean of a multi-surface cyclic plasticity model of the Masing-Prandtl-Ishlinskii-Iwan (MPII) type. Its major advantage is that the rheology is characterized by few commonly measured parameters. Ground motions are computed at the surface of soil profiles in the Tohoku area (Japan) by propagating 3C signals recorded at rock outcrops, during the 2011 Tohoku earthquake. Computed surface ground motions are compared to the Tohoku earthquake records at alluvial ...

  12. Comparison of measurements and model results for airborne sulphur and nitrogen components with kriging

    Energy Technology Data Exchange (ETDEWEB)

    Schaug, J.; Iversen, T.; Pedersen, U. (Norwegian Institute for Air Research, Lillestroem (Norway). Chemical Coordinating Centre of EMEP)

    1993-04-01

    Comparisons have been made between calculations from the Lagrangian model for acid deposition at Meteorological Synthesizing Centre-West (MSC-W) of EMEP and measurements at EMEP sites. Annual averages of aerosol sulphate, sulphate in precipitation and nitrate in precipitation were calculated and compared for selected sites. Site selection was based on data completeness and on results from EMEP interlaboratory exercises. The comparison for sulphates in precipitation and air led to a model underestimation in the north and model overestimation in a belt through the major source regions in central Europe. The comparisons also indicate irregularities at some sites which may be due to influence from local sources, or the data quality, although this is not substantiated. The model estimates of nitrate in precipitation compare well with the measurements, although some characteristic differences occur also for this component. 21 refs., 11 figs., 2 tabs.

  13. Level shift two-components autoregressive conditional heteroscedasticity modelling for WTI crude oil market

    Science.gov (United States)

    Sin, Kuek Jia; Cheong, Chin Wen; Hooi, Tan Siow

    2017-04-01

    This study aims to investigate the crude oil volatility using a two components autoregressive conditional heteroscedasticity (ARCH) model with the inclusion of abrupt jump feature. The model is able to capture abrupt jumps, news impact, clustering volatility, long persistence volatility and heavy-tailed distributed error which are commonly observed in the crude oil time series. For the empirical study, we have selected the WTI crude oil index from year 2000 to 2016. The results found that by including the multiple-abrupt jumps in ARCH model, there are significant improvements of estimation evaluations as compared with the standard ARCH models. The outcomes of this study can provide useful information for risk management and portfolio analysis in the crude oil markets.

  14. Mold appearance and modeling on selected corn stover components during moisture sorption.

    Science.gov (United States)

    Igathinathane, C; Womac, A R; Pordesimo, L O; Sokhansanj, S

    2008-09-01

    Occurrence of mold was visually monitored for 26days on samples of major anatomical components of corn stover maintained at several storage temperatures (T) and water activities (a(w)). Glass desiccators with saturated salt solutions placed in temperature controlled chambers provided simulated storage conditions with temperatures ranging from 10 degrees C to 40 degrees C and water activities ranging from 0.11 to 0.98. Mold affected leaf, stalk skin, and stalk pith equally at water activity greater than 0.9. As expected, a combination of increased water activity greater than 0.9 and temperatures greater than 30 degrees C was conducive to mold growth. Based on material moisture content during the initial mold growth, it was postulated that among the corn stover components the stalk pith was the least resistant to mold growth followed by stalk skin and leaf for the studied range of temperature and water activity. Mold growth models fitted well with the observation. A linear mold-free days predictions using a three-parameter regression model (T, a(w), and T x a(w)) was superior (R(2)=0.99) to other models considered. The exponential spoilage model using two parameter T and a(w) also gave comparable performance (R(2)=0.95). Among the independent factors, T x a(w) product was the most significant (p=0.0069) followed by T (p=0.0114), and a(w) (p=0.3140) in explaining the experimental data. The developed models can be applied to predict the safe storage period of corn stover components exposed to various temperature and moisture environmental conditions.

  15. Fast and Accurate Radiative Transfer Calculations Using Principal Component Analysis for (Exo-)Planetary Retrieval Models

    Science.gov (United States)

    Kopparla, P.; Natraj, V.; Shia, R. L.; Spurr, R. J. D.; Crisp, D.; Yung, Y. L.

    2015-12-01

    Radiative transfer (RT) computations form the engine of atmospheric retrieval codes. However, full treatment of RT processes is computationally expensive, prompting usage of two-stream approximations in current exoplanetary atmospheric retrieval codes [Line et al., 2013]. Natraj et al. [2005, 2010] and Spurr and Natraj [2013] demonstrated the ability of a technique using principal component analysis (PCA) to speed up RT computations. In the PCA method for RT performance enhancement, empirical orthogonal functions are developed for binned sets of inherent optical properties that possess some redundancy; costly multiple-scattering RT calculations are only done for those few optical states corresponding to the most important principal components, and correction factors are applied to approximate radiation fields. Kopparla et al. [2015, in preparation] extended the PCA method to a broadband spectral region from the ultraviolet to the shortwave infrared (0.3-3 micron), accounting for major gas absorptions in this region. Here, we apply the PCA method to a some typical (exo-)planetary retrieval problems. Comparisons between the new model, called Universal Principal Component Analysis Radiative Transfer (UPCART) model, two-stream models and line-by-line RT models are performed, for spectral radiances, spectral fluxes and broadband fluxes. Each of these are calculated at the top of the atmosphere for several scenarios with varying aerosol types, extinction and scattering optical depth profiles, and stellar and viewing geometries. We demonstrate that very accurate radiance and flux estimates can be obtained, with better than 1% accuracy in all spectral regions and better than 0.1% in most cases, as compared to a numerically exact line-by-line RT model. The accuracy is enhanced when the results are convolved to typical instrument resolutions. The operational speed and accuracy of UPCART can be further improved by optimizing binning schemes and parallelizing the codes, work

  16. A four-component model of age-related memory change.

    Science.gov (United States)

    Healey, M Karl; Kahana, Michael J

    2016-01-01

    We develop a novel, computationally explicit, theory of age-related memory change within the framework of the context maintenance and retrieval (CMR2) model of memory search. We introduce a set of benchmark findings from the free recall and recognition tasks that include aspects of memory performance that show both age-related stability and decline. We test aging theories by lesioning the corresponding mechanisms in a model fit to younger adult free recall data. When effects are considered in isolation, many theories provide an adequate account, but when all effects are considered simultaneously, the existing theories fail. We develop a novel theory by fitting the full model (i.e., allowing all parameters to vary) to individual participants and comparing the distributions of parameter values for older and younger adults. This theory implicates 4 components: (a) the ability to sustain attention across an encoding episode, (b) the ability to retrieve contextual representations for use as retrieval cues, (c) the ability to monitor retrievals and reject intrusions, and (d) the level of noise in retrieval competitions. We extend CMR2 to simulate a recognition memory task using the same mechanisms the free recall model uses to reject intrusions. Without fitting any additional parameters, the 4-component theory that accounts for age differences in free recall predicts the magnitude of age differences in recognition memory accuracy. Confirming a prediction of the model, free recall intrusion rates correlate positively with recognition false alarm rates. Thus, we provide a 4-component theory of a complex pattern of age differences across 2 key laboratory tasks.

  17. A Four–Component Model of Age–Related Memory Change

    Science.gov (United States)

    Healey, M. Karl; Kahana, Michael J.

    2015-01-01

    We develop a novel, computationally explicit, theory of age–related memory change within the framework of the context maintenance and retrieval (CMR2) model of memory search. We introduce a set of benchmark findings from the free recall and recognition tasks that includes aspects of memory performance that show both age-related stability and decline. We test aging theories by lesioning the corresponding mechanisms in a model fit to younger adult free recall data. When effects are considered in isolation, many theories provide an adequate account, but when all effects are considered simultaneously, the existing theories fail. We develop a novel theory by fitting the full model (i.e., allowing all parameters to vary) to individual participants and comparing the distributions of parameter values for older and younger adults. This theory implicates four components: 1) the ability to sustain attention across an encoding episode, 2) the ability to retrieve contextual representations for use as retrieval cues, 3) the ability to monitor retrievals and reject intrusions, and 4) the level of noise in retrieval competitions. We extend CMR2 to simulate a recognition memory task using the same mechanisms the free recall model uses to reject intrusions. Without fitting any additional parameters, the four–component theory that accounts for age differences in free recall predicts the magnitude of age differences in recognition memory accuracy. Confirming a prediction of the model, free recall intrusion rates correlate positively with recognition false alarm rates. Thus we provide a four–component theory of a complex pattern of age differences across two key laboratory tasks. PMID:26501233

  18. DEVELOPMENT OF A GIS DATA MODEL WITH SPATIAL,TEMPORAL AND ATTRIBUTE COMPONENTS BASED ON OBJECT-ORIENTED APPROACH

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper presents a conceptual data model, the STA-model, for handling spatial, temporal and attribute aspects of objects in GIS. The model is developed on the basis of object-oriented modeling approach. This model includes two major parts: (a) modeling the signal objects by STA-object elements, and (b) modeling relationships between STA-objects. As an example, the STA-model is applied for modeling land cover change data with spatial, temporal and attribute components.

  19. A Note Comparing Component-Slope, Scheffé, and Cox Parameterizations of the Linear Mixture Experiment Model

    Energy Technology Data Exchange (ETDEWEB)

    Piepel, Gregory F.

    2006-05-01

    A mixture experiment involves combining two or more components in various proportions and collecting data on one or more responses. A linear mixture model may adequately represent the relationship between a response and mixture component proportions and be useful in screening the mixture components. The Scheffé and Cox parameterizations of the linear mixture model are commonly used for analyzing mixture experiment data. With the Scheffé parameterization, the fitted coefficient for a component is the predicted response at that pure component (i.e., single-component mixture). With the Cox parameterization, the fitted coefficient for a mixture component is the predicted difference in response at that pure component and at a pre-specified reference composition. This paper presents a new component-slope parameterization, in which the fitted coefficient for a mixture component is the predicted slope of the linear response surface along the direction determined by that pure component and at a pre-specified reference composition. The component-slope, Scheffé, and Cox parameterizations of the linear mixture model are compared and their advantages and disadvantages are discussed.

  20. Investigating groundwater flow components in an Alpine relict rock glacier (Austria) using a numerical model

    Science.gov (United States)

    Pauritsch, Marcus; Wagner, Thomas; Winkler, Gerfried; Birk, Steffen

    2017-03-01

    Relict rock glaciers are complex hydrogeological systems that might act as relevant groundwater storages; therefore, the discharge behavior of these alpine landforms needs to be better understood. Hydrogeological and geophysical investigations at a relict rock glacier in the Niedere Tauern Range (Austria) reveal a slow and fast flow component that appear to be related to the heterogeneous structure of the aquifer. A numerical groundwater flow model was used to indicate the influence of important internal structures such as layering, preferential flow paths and aquifer-base topography. Discharge dynamics can be reproduced reasonably by both introducing layers of strongly different hydraulic conductivities or by a network of highly conductive channels within a low-conductivity zone. Moreover, the topography of the aquifer base influences the discharge dynamics, which can be observed particularly in simply structured aquifers. Hydraulic conductivity differences of three orders of magnitude are required to account for the observed discharge behavior: a highly conductive layer and/or channel network controlling the fast and flashy spring responses to recharge events, as opposed to less conductive sediment accumulations sustaining the long-term base flow. The results show that the hydraulic behavior of this relict rock glacier and likely that of others can be adequately represented by two aquifer components. However, the attempt to characterize the two components by inverse modeling results in ambiguity of internal structures when solely discharge data are available.

  1. Forward modelling of multi-component induction logging tools in layered anisotropic dipping formations

    Science.gov (United States)

    Gao, Jie; Xu, Chenhao; Xiao, Jiaqi

    2013-10-01

    Multi-component induction logging provides great assistance in the exploration of thinly laminated reservoirs. The 1D parametric inversion following an adaptive borehole correction is the key step in the data processing of multi-component induction logging responses. To make the inversion process reasonably fast, an efficient forward modelling method is necessary. In this paper, a modelling method has been developed to simulate the multi-component induction tools in deviated wells drilled in layered anisotropic formations. With the introduction of generalized reflection coefficients, the analytic expressions of magnetic field in the form of a Sommerfeld integral were derived. The fast numerical computation of the integral has been completed by using the fast Fourier-Hankel transform and fast Hankel transform methods. The latter is so time efficient that it is competent enough for real-time multi-parameter inversion. In this paper, some simulated results have been presented and they are in excellent agreement with the finite difference method code's solution.

  2. Investigating groundwater flow components in an Alpine relict rock glacier (Austria) using a numerical model

    Science.gov (United States)

    Pauritsch, Marcus; Wagner, Thomas; Winkler, Gerfried; Birk, Steffen

    2016-11-01

    Relict rock glaciers are complex hydrogeological systems that might act as relevant groundwater storages; therefore, the discharge behavior of these alpine landforms needs to be better understood. Hydrogeological and geophysical investigations at a relict rock glacier in the Niedere Tauern Range (Austria) reveal a slow and fast flow component that appear to be related to the heterogeneous structure of the aquifer. A numerical groundwater flow model was used to indicate the influence of important internal structures such as layering, preferential flow paths and aquifer-base topography. Discharge dynamics can be reproduced reasonably by both introducing layers of strongly different hydraulic conductivities or by a network of highly conductive channels within a low-conductivity zone. Moreover, the topography of the aquifer base influences the discharge dynamics, which can be observed particularly in simply structured aquifers. Hydraulic conductivity differences of three orders of magnitude are required to account for the observed discharge behavior: a highly conductive layer and/or channel network controlling the fast and flashy spring responses to recharge events, as opposed to less conductive sediment accumulations sustaining the long-term base flow. The results show that the hydraulic behavior of this relict rock glacier and likely that of others can be adequately represented by two aquifer components. However, the attempt to characterize the two components by inverse modeling results in ambiguity of internal structures when solely discharge data are available.

  3. The largest strongly connected component in the cyclical pedigree model of Wakeley et al.

    Science.gov (United States)

    Blath, Jochen; Kadow, Stephan; Ortgiese, Marcel

    2014-12-01

    We establish a link between Wakeley et al.'s (2012) cyclical pedigree model from population genetics and a randomized directed configuration model (DCM) considered by Cooper and Frieze (2004). We then exploit this link in combination with asymptotic results for the in-degree distribution of the corresponding DCM to compute the asymptotic size of the largest strongly connected component S(N) (where N is the population size) of the DCM resp. the pedigree. The size of the giant component can be characterized explicitly (amounting to approximately 80% of the total populations size) and thus contributes to a reduced 'pedigree effective population size'. In addition, the second largest strongly connected component is only of size O(logN). Moreover, we describe the size and structure of the 'domain of attraction' of S(N). In particular, we show that with high probability for any individual the shortest ancestral line reaches S(N) after O(loglogN) generations, while almost all other ancestral lines take at most O(logN) generations. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. A Three-Component Model for Magnetization Transfer. Solution by Projection-Operator Technique, and Application to Cartilage

    Science.gov (United States)

    Adler, Ronald S.; Swanson, Scott D.; Yeung, Hong N.

    1996-01-01

    A projection-operator technique is applied to a general three-component model for magnetization transfer, extending our previous two-component model [R. S. Adler and H. N. Yeung,J. Magn. Reson. A104,321 (1993), and H. N. Yeung, R. S. Adler, and S. D. Swanson,J. Magn. Reson. A106,37 (1994)]. The PO technique provides an elegant means of deriving a simple, effective rate equation in which there is natural separation of relaxation and source terms and allows incorporation of Redfield-Provotorov theory without any additional assumptions or restrictive conditions. The PO technique is extended to incorporate more general, multicomponent models. The three-component model is used to fit experimental data from samples of human hyaline cartilage and fibrocartilage. The fits of the three-component model are compared to the fits of the two-component model.

  5. Freshwater DOM quantity and quality from a two-component model of UV absorbance

    Science.gov (United States)

    Carter, Heather T.; Tipping, Edward; Koprivnjak, Jean-Francois; Miller, Matthew P.; Cookson, Brenda; Hamilton-Taylor, John

    2012-01-01

    We present a model that considers UV-absorbing dissolved organic matter (DOM) to consist of two components (A and B), each with a distinct and constant spectrum. Component A absorbs UV light strongly, and is therefore presumed to possess aromatic chromophores and hydrophobic character, whereas B absorbs weakly and can be assumed hydrophilic. We parameterised the model with dissolved organic carbon concentrations [DOC] and corresponding UV spectra for c. 1700 filtered surface water samples from North America and the United Kingdom, by optimising extinction coefficients for A and B, together with a small constant concentration of non-absorbing DOM (0.80 mg DOC L-1). Good unbiased predictions of [DOC] from absorbance data at 270 and 350 nm were obtained (r2 = 0.98), the sum of squared residuals in [DOC] being reduced by 66% compared to a regression model fitted to absorbance at 270 nm alone. The parameterised model can use measured optical absorbance values at any pair of suitable wavelengths to calculate both [DOC] and the relative amounts of A and B in a water sample, i.e. measures of quantity and quality. Blind prediction of [DOC] was satisfactory for 9 of 11 independent data sets (181 of 213 individual samples).

  6. Development of the component models for the KALIMER safety analysis code SSC-K

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Young Min; Lee, Yong Bum; Chang, Won Pyo [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-05-01

    The SSC-K code is intended to simulate system responses to operational transients or accidents of the pool-type KALIMER (Korea Advanced Liquid Metal Reactor). As a part of the SSC-K development task, some primary component models have been developed and generalized correlations were recommended based on the technical review. Plant modules for the PSDRS, EMP were developed based on the analytical models. The IHX model of SSC-L was modified to take into account the thermo-hydraulic characteristics of pool. Correlations used for piping and in-core assemblies were reviewed and user options were provided for SSC-K. The merged version of SSC-K with PSDRE program was proved out to be valid by test run of ULOHS. The developed component models will be implemented into the SSC-K code and options will be provided for user to select proper correlations for friction factor and heat transfer coefficients. 30 refs., 31 figs., 9 tabs. (Author)

  7. What Time Is Sunrise? Revisiting the Refraction Component of Sunrise/set Prediction Models

    Science.gov (United States)

    Wilson, Teresa; Bartlett, Jennifer L.; Hilton, James Lindsay

    2017-01-01

    Algorithms that predict sunrise and sunset times currently have an error of one to four minutes at mid-latitudes (0° - 55° N/S) due to limitations in the atmospheric models they incorporate. At higher latitudes, slight changes in refraction can cause significant discrepancies, even including difficulties determining when the Sun appears to rise or set. While different components of refraction are known, how they affect predictions of sunrise/set has not yet been quantified. A better understanding of the contributions from temperature profile, pressure, humidity, and aerosols could significantly improve the standard prediction. We present a sunrise/set calculator that interchanges the refraction component by varying the refraction model. We then compare these predictions with data sets of observed rise/set times to create a better model. Sunrise/set times and meteorological data from multiple locations will be necessary for a thorough investigation of the problem. While there are a few data sets available, we will also begin collecting this data using smartphones as part of a citizen science project. The mobile application for this project will be available in the Google Play store. Data analysis will lead to more complete models that will provide more accurate rise/set times for the benefit of astronomers, navigators, and outdoorsmen everywhere.

  8. Continuous motion decoding from EMG using independent component analysis and adaptive model training.

    Science.gov (United States)

    Zhang, Qin; Xiong, Caihua; Chen, Wenbin

    2014-01-01

    Surface Electromyography (EMG) is popularly used to decode human motion intention for robot movement control. Traditional motion decoding method uses pattern recognition to provide binary control command which can only move the robot as predefined limited patterns. In this work, we proposed a motion decoding method which can accurately estimate 3-dimensional (3-D) continuous upper limb motion only from multi-channel EMG signals. In order to prevent the muscle activities from motion artifacts and muscle crosstalk which especially obviously exist in upper limb motion, the independent component analysis (ICA) was applied to extract the independent source EMG signals. The motion data was also transferred from 4-manifold to 2-manifold by the principle component analysis (PCA). A hidden Markov model (HMM) was proposed to decode the motion from the EMG signals after the model trained by an adaptive model identification process. Experimental data were used to train the decoding model and validate the motion decoding performance. By comparing the decoded motion with the measured motion, it is found that the proposed motion decoding strategy was feasible to decode 3-D continuous motion from EMG signals.

  9. Bee venom and its component apamin as neuroprotective agents in a Parkinson disease mouse model.

    Directory of Open Access Journals (Sweden)

    Daniel Alvarez-Fischer

    Full Text Available Bee venom has recently been suggested to possess beneficial effects in the treatment of Parkinson disease (PD. For instance, it has been observed that bilateral acupoint stimulation of lower hind limbs with bee venom was protective in the acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP mouse model of PD. In particular, a specific component of bee venom, apamin, has previously been shown to have protective effects on dopaminergic neurons in vitro. However, no information regarding a potential protective action of apamin in animal models of PD is available to date. The specific goals of the present study were to (i establish that the protective effect of bee venom for dopaminergic neurons is not restricted to acupoint stimulation, but can also be observed using a more conventional mode of administration and to (ii demonstrate that apamin can mimic the protective effects of a bee venom treatment on dopaminergic neurons. Using the chronic mouse model of MPTP/probenecid, we show that bee venom provides sustained protection in an animal model that mimics the chronic degenerative process of PD. Apamin, however, reproduced these protective effects only partially, suggesting that other components of bee venom enhance the protective action of the peptide.

  10. Two-dimensional, isothermal, multi-component model for a polymer electrolyte membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Mahinpey, N.; Jagannathan, A.; Idem, R. [Regina Univ., SK (Canada). Faculty of Engineering

    2007-07-01

    A fuel cell is an electrochemical energy conversion device which is more efficient than an internal combustion engine in converting fuel to power. Numerous fuel cell models have been developed by a number of authors accounting for the various physical processes. Earlier models were restricted to being one dimensional, steady-state, and isothermal while more recent two-dimensional models had several limitations. This paper presented the results of a study that developed a two-dimensional computational fluid dynamics model of a polymer electrolyte membrane fuel cell using a finite element method to solve a multi-component transport model coupled with flow in porous media, charge balance, electrochemical kinetics, and rigorous water balance in the membrane. The mass transport, momentum transport, and electrochemical processes occurring in the membrane electrolyte and catalyst layers were modeled. The local equilibrium was assumed at the interfaces and the model was combined with the kinetics and was analytically solved for the anodic and cathodic current using an agglomerate spherical catalyst pellet. The paper compared the modeling results with previously published experimental data. The study investigated the effects of channel and bipolar plate shoulder size, porosity of the electrodes, temperature, relative humidity and current densities on the cell performance. It was concluded that smaller sized channels and bipolar plate shoulders were required to obtain higher current densities, although larger channels were satisfactory at moderate current densities. 13 refs., 5 figs.

  11. Griffin and Neal's safety model: Determinants and components of individual safety performance in the Italian context.

    Science.gov (United States)

    Toderi, S; Gaggia, A; Mariani, M G; Mancini, G; Broccoli, M

    2015-11-22

    Griffin and Neal's model is a useful model to understand workers' different safety behaviour (compliance and participation) starting from their mastery of safety procedures (safety knowledge) and the motivation to put them in place (safety motivation). Although the theoretical model has proven to be adequate and is widely used in research, two problems arise: 1) there is no Italian validation of the four scales measuring the key constructs of the model; 2) the hypothesis regarding the differential impact of the determinants on the components of safety performance produced mixed evidence. The study had a twofold objective: 1) validate an Italian version of the four scales, primarily assessing their construct validity; 2) verify the relationships between the constructs according to the assumptions made within the theoretical model. The psychometric properties of the scales as well as the relationships between the constructs were investigated in a sample of 277 workers in the construction and logistics sectors, using questionnaires. The analyses were based on the use of structural equation modelling technique. Results confirmed the validity and reliability of the Italian scales, showing indices that were both satisfactory and aligned with those from previous studies. The relationships between the constructs were substantially consistent with the safety model. The study provided a valid version of the scales measuring determinants and components of individual safe performance. Such scales can be appropriately used in the Italian context for the development of theoretical as well as practical contributions on work safety. The results suggest that interventions to increase overall safe performance should address both knowledge and motivation for safety.

  12. Towards a three-component model of fan loyalty: a case study of Chinese youth.

    Science.gov (United States)

    Zhang, Xiao-xiao; Liu, Li; Zhao, Xian; Zheng, Jian; Yang, Meng; Zhang, Ji-qi

    2015-01-01

    The term "fan loyalty" refers to the loyalty felt and expressed by a fan towards the object of his/her fanaticism in both everyday and academic discourses. However, much of the literature on fan loyalty has paid little attention to the topic from the perspective of youth pop culture. The present study explored the meaning of fan loyalty in the context of China. Data were collected by the method of in-depth interviews with 16 young Chinese people aged between 19 and 25 years who currently or once were pop fans. The results indicated that fan loyalty entails three components: involvement, satisfaction, and affiliation. These three components regulate the process of fan loyalty development, which can be divided into four stages: inception, upgrade, zenith, and decline. This model provides a conceptual explanation of why and how young Chinese fans are loyal to their favorite stars. The implications of the findings are discussed.

  13. Towards a three-component model of fan loyalty: a case study of Chinese youth.

    Directory of Open Access Journals (Sweden)

    Xiao-xiao Zhang

    Full Text Available The term "fan loyalty" refers to the loyalty felt and expressed by a fan towards the object of his/her fanaticism in both everyday and academic discourses. However, much of the literature on fan loyalty has paid little attention to the topic from the perspective of youth pop culture. The present study explored the meaning of fan loyalty in the context of China. Data were collected by the method of in-depth interviews with 16 young Chinese people aged between 19 and 25 years who currently or once were pop fans. The results indicated that fan loyalty entails three components: involvement, satisfaction, and affiliation. These three components regulate the process of fan loyalty development, which can be divided into four stages: inception, upgrade, zenith, and decline. This model provides a conceptual explanation of why and how young Chinese fans are loyal to their favorite stars. The implications of the findings are discussed.

  14. A component decomposition model for evaluating atmospheric effects in remote sensing

    Science.gov (United States)

    Li, S.; Wan, Z. M.; Dozier, J.

    1987-01-01

    A radiance value of a target pixel recorded by a remote sensor can be decomposed into three components: (1) attenuated target signature, (2) pure atmospheric radiation, and (3) the contribution made by the ground through the atmospheric scattering process. Given the meteorological and optical parameters of a layer-structured atmosphere, its transmittance and radiance distribution can be accurately calculated with a plane-parallel radiative transfer model. For a uniform surface, the ground contribution can be obtained by comparing radiances for an atmosphere over a black but nonemitting surface and the same atmosphere with an underlying ground of given albedo or temperature. For an inhomogeneous surface, the first two components remain the same as long as the surface is a plane. The third may be estimated using the locally averaged top-of-atmosphere radiance. An atmospheric point spread function is calculated by a Monte Carlo approach and is used for retrieving the ground signature through a deconvolution procedure.

  15. Evaluating the hydrological component of the new catchment-scale sediment delivery model LAPSUS-D

    Science.gov (United States)

    Keesstra, S. D.; Temme, A. J. A. M.; Schoorl, J. M.; Visser, S. M.

    2014-05-01

    Physically-based, catchment scale sediment delivery models have become increasingly complex, sophisticated and are suitable for a diverse range of environmental contexts. However, in their attempts to best represent the physical processes of erosion and deposition, these models require large and detailed input datasets. When such data are unavailable, annual sediment yield models are relied upon. However, in this class of models, widely available data such as daily precipitation and discharge are disregarded resulting in a reduction in temporal accuracy. To fill this scientific and management gap, the landscape evolution model LAPSUS was adapted (LAPSUS-D) for a meso-scale catchment to model sediment yield on a daily resolution. The water balance component within the model enables the calibration of the model in terms of water discharge with measured daily discharge at the outlet. This methodology is especially important when modeling sediment yield from catchments which are ungaged catchments in terms of sediment, but where hydrological data are available. As the simulation of sediment yield was the main objective of the study, the calibration focused on peak discharge. The focus on peak discharge provides insight into the capability of the model to generate, route and deliver sediment at the outlet of a meso-scale catchment. LAPSUS-D has daily temporal resolution and requires a 10 to 30 m pixel size DEM, soil map, land-use map and daily hydrological records (precipitation and discharge). In this paper we present the first assessment of the hydrological model performance and an analysis of the sensitivity of the model to input parameters. Our study site is a 23-km2 catchment in Upper Nysa Szalona, southwest Poland with temperate climate.

  16. Illuminating the theoretical components of alexithymia using bifactor modeling and network analysis.

    Science.gov (United States)

    Watters, Carolyn A; Taylor, Graeme J; Bagby, R Michael

    2016-06-01

    Alexithymia is a multifaceted personality construct that reflects deficits in affect awareness (difficulty identifying feelings, DIF; difficulty describing feelings, DDF) and operative thinking (externally oriented thinking, EOT; restricted imaginal processes, IMP), and is associated with several common psychiatric disorders. Over the years, researchers have debated the components that comprise the construct with some suggesting that IMP and EOT may reflect constructs somewhat distinct from alexithymia. In this investigation, we attempt to clarify the components and their interrelationships using a large heterogeneous multilanguage sample (N = 839), and an interview-based assessment of alexithymia (Toronto Structured Interview for Alexithymia; TSIA). To this end, we used 2 distinctly different but complementary methods, bifactor modeling and network analysis. Results of the confirmatory bifactor model and related reliability estimates supported a strong general factor of alexithymia; however, the majority of reliable variance for IMP was independent of this general factor. In contrast, network analysis results were based on a network comprised of only substantive partial correlations among TSIA items. Modularity analysis revealed 3 communities of items, where DIF and DDF formed 1 community, and EOT and IMP formed separate communities. Network metrics supported that the majority of central items resided in the DIF/DDF community and that IMP items were connected to the network primarily through EOT. Taken together, results suggest that IMP, at least as measured by the TSIA, may not be as salient a component of the alexithymia construct as are the DIF, DDF, and EOT components. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  17. Cosmology beyond the standard model: Multi-component dark matter model

    Science.gov (United States)

    Demiański, M.; Doroshkevich, A. G.

    2015-06-01

    We show that both the mass and composition of dark matter (DM) particles strongly influence the formation of low mass DM halos. Comparison of theoretical predictions with observations allows us to select the more promising DM models. More details can be found in our paper arXiv:1404.3362.

  18. Free vibration analysis of civil engineering structures by component-wise models

    Science.gov (United States)

    Carrera, Erasmo; Pagani, Alfonso

    2014-09-01

    Higher-order beam models are used in this paper to carry out free vibration analysis of civil engineering structures. Refined kinematic fields are developed using the Carrera Unified Formulation (CUF), which allows for the implementation of any-order theory without the need for ad hoc formulations. The principle of virtual displacements in conjunction with the finite element method (FEM) is used to formulate stiffness and mass matrices in terms of fundamental nuclei. The nuclei depend neither on the adopted class of beam theory nor on the FEM approximation along the beam axis. This paper focuses on a particular class of CUF models that makes use of Lagrange polynomials to discretize cross-sectional displacement variables. This class of models are referred to as component-wise (CW) in recent works. According to the CW approach, each structural component (e.g. columns, walls, frame members, and floors) can be modeled by means of the same 1D formulation. A number of typical civil engineering structures (e.g. simple beams, arches, truss structures, and complete industrial and civil buildings) are analyzed and CW results are compared to classical beam theories (Euler-Bernoulli and Timoshenko), refined beam models based on Taylor-like expansions of the displacements on the cross-section, and classical solid/shell FEM solutions from the commercial code MSC Nastran. The results highlight the enhanced capabilities of the proposed formulation. It is in fact demonstrated that CW models are able to replicate 3D solid results with very low computational efforts.

  19. Methodology for the Incorporation of Passive Component Aging Modeling into the RAVEN/ RELAP-7 Environment

    Energy Technology Data Exchange (ETDEWEB)

    Mandelli, Diego; Rabiti, Cristian; Cogliati, Joshua; Alfonsi, Andrea; Askin Guler; Tunc Aldemir

    2014-11-01

    Passive system, structure and components (SSCs) will degrade over their operation life and this degradation may cause to reduction in the safety margins of a nuclear power plant. In traditional probabilistic risk assessment (PRA) using the event-tree/fault-tree methodology, passive SSC failure rates are generally based on generic plant failure data and the true state of a specific plant is not reflected realistically. To address aging effects of passive SSCs in the traditional PRA methodology [1] does consider physics based models that account for the operating conditions in the plant, however, [1] does not include effects of surveillance/inspection. This paper represents an overall methodology for the incorporation of aging modeling of passive components into the RAVEN/RELAP-7 environment which provides a framework for performing dynamic PRA. Dynamic PRA allows consideration of both epistemic and aleatory uncertainties (including those associated with maintenance activities) in a consistent phenomenological and probabilistic framework and is often needed when there is complex process/hardware/software/firmware/ human interaction [2]. Dynamic PRA has gained attention recently due to difficulties in the traditional PRA modeling of aging effects of passive components using physics based models and also in the modeling of digital instrumentation and control systems. RAVEN (Reactor Analysis and Virtual control Environment) [3] is a software package under development at the Idaho National Laboratory (INL) as an online control logic driver and post-processing tool. It is coupled to the plant transient code RELAP-7 (Reactor Excursion and Leak Analysis Program) also currently under development at INL [3], as well as RELAP 5 [4]. The overall methodology aims to: • Address multiple aging mechanisms involving large number of components in a computational feasible manner where sequencing of events is conditioned on the physical conditions predicted in a simulation

  20. Two-component model of the interaction of an interstellar cloud with surrounding hot plasma

    CERN Document Server

    Provornikova, E A; Lallement, R

    2011-01-01

    We present a two-component gasdynamic model of an interstellar cloud embedded in a hot plasma. It is assumed that the cloud consists of atomic hydrogen gas, interstellar plasma is quasineutral. Hydrogen atoms and plasma protons interact through a charge exchange process. Magnetic felds and radiative processes are ignored in the model. The influence of heat conduction within plasma on the interaction between a cloud and plasma is studied. We consider the extreme case and assume that hot plasma electrons instantly heat the plasma in the interaction region and that plasma flow can be described as isothermal. Using the two-component model of the interaction of cold neutral cloud and hot plasma, we estimate the lifetime of interstellar clouds. We focus on the clouds typical for the cluster of local interstellar clouds embedded in the hot Local Bubble and give an estimate of the lifetime of the Local interstellar cloud where the Sun currently travels. The charge transfer between highly charged plasma ions and neutr...