WorldWideScience

Sample records for debris environment model

  1. LEGEND, a LEO-to-GEO Environment Debris Model

    Science.gov (United States)

    Liou, Jer Chyi; Hall, Doyle T.

    2013-01-01

    LEGEND (LEO-to-GEO Environment Debris model) is a three-dimensional orbital debris evolutionary model that is capable of simulating the historical and future debris populations in the near-Earth environment. The historical component in LEGEND adopts a deterministic approach to mimic the known historical populations. Launched rocket bodies, spacecraft, and mission-related debris (rings, bolts, etc.) are added to the simulated environment. Known historical breakup events are reproduced, and fragments down to 1 mm in size are created. The LEGEND future projection component adopts a Monte Carlo approach and uses an innovative pair-wise collision probability evaluation algorithm to simulate the future breakups and the growth of the debris populations. This algorithm is based on a new "random sampling in time" approach that preserves characteristics of the traditional approach and captures the rapidly changing nature of the orbital debris environment. LEGEND is a Fortran 90-based numerical simulation program. It operates in a UNIX/Linux environment.

  2. The MASTER-99 space debris and meteoroid environment model

    Science.gov (United States)

    Klinkrad, H.; Bendisch, J.; Bunte, K. D.; Krag, H.; Sdunnus, H.; Wegener, P.

    2001-01-01

    MASTER-99 is a space debris and meteoroid environment model produced by TU Braunschweig (D), eta_max space (D), and DERA (UK) under an ESA contract. The model allows to compute particulate impact fluxes on any terrestrial target orbit up to geostationary altitudes. Flux contributions can be discriminated with respect to debris source types (catalog objects, explosion and collision fragments, NaK droplets, solid rocket motor dust and slag, impact ejecta, and surface degradation products), meteoroid source types (Divine-Staubach populations, and annual stream events), and with respect to origin and impact direction of each flux contributing particulate. Impact fluxes of meteoroids and debris down to 1 μm sizes can be determined for spherical targets, for tumbling plates, or for oriented, planar surfaces which are controlled according to standard attitude steering laws. MASTER-99 is distributed by ESA/ESOC on a CD ROM which includes user documentation, and the necessary data files, executables, and GUI driven installation scripts for the most common operating systems and computer platforms. MASTER-99 is delivered together with PROOF-99, a program for radar and optical observation forecasting. Based on the MASTER-99 population larger than 1 mm, it predicts debris detections from ground-based or space-based sensors (radars or telescopes) of user-defined system performances.

  3. A Review of the Recent NASA Long-Term Orbital Debris Environment Projection and Active Debris Removal Modeling Activities

    Science.gov (United States)

    Liou, J.C.

    2009-01-01

    The NASA Orbital Debris Program Office (ODPO) developed a high fidelity debris evolutionary model, LEGEND (a LEO-to-GEO Environment Debris model), in 2004 to enhance its capability to better model the near-Earth environment. LEGEND can mimic the growth of the historical debris population and project it into the future based on user-defined scenarios. The first major LEGEND study concluded that even without any future launches, the LEO population would continue to increase due to mutual collisions among existing objects. In reality, the increase will be worse than this prediction because of ongoing satellite launches and unexpected major breakups. Even with a full implementation of the commonly-adopted mitigation measures, the LEO population growth is inevitable. To preserve the near-Earth environment for future generations, active debris removal (ADR) must be considered. A follow-up LEGEND ADR study was completed recently. The main results indicate that (1) the mass and collision probability of each object can be used to establish an effective removal selection criterion and (2) a removal rate of 5 objects per year is sufficient to stabilize the LEO environment. Due to the limitation of removal techniques, however, different target selection criteria (in size, altitude, inclination, etc.) may be more practical. A careful evaluation of the effectiveness of different proposed techniques must be carried out to maximize the long-term benefit to the environment.

  4. Review of current activities to model and measure the orbital debris environment in low-earth orbit

    Science.gov (United States)

    Reynolds, R. C.

    A very active orbital debris program is currently being pursued at the NASA/Johnson Space Center (JSC), with projects designed to better define the current environment, to project future environments, to model the processes contributing to or constraining the growth of debris in the environment, and to gather supporting data needed to improve the understanding of the orbital debris problem and the hazard it presents to spacecraft. This paper is a review of the activity being conducted at JSC, by NASA, Lockheed Engineering and Sciences Company, and other support contractors, and presents a review of current activity, results of current research, and a discussion of directions for future development.

  5. Updating the NASA LEO Orbital Debris Environment Model with Recent Radar and Optical Observations and in Situ Measurements

    Science.gov (United States)

    Liou, J.-C.; Anz-Meador, P.; Matney, M. J.; Kessler, D. J.; Theall, J.; Johnson, N. L.

    2000-01-01

    The Low Earth Orbit (LEO, between 200 and 2000 km altitudes) debris environment has been constantly measured by NASA Johnson Space Center's Liquid Mirror Telescope (LMT) since 1996 (Africano et al. 1999, NASA JSC-28826) and by Haystack and Haystack Auxiliary radars at MIT Lincoln Laboratory since 1990 (Settecerri et al. 1999, NASA JSC-28744). Debris particles as small as 3 mm can be detected by the radars and as small as 3 cm can be measured by LMT. Objects about 10 cm in diameter and greater are tracked and catalogued by the US Space Surveillance Network. Much smaller (down to several micrometers) natural and debris particle populations can be estimated based on in situ measurements, such as Long Duration Exposure Facility, and based on analyses of returned surfaces, such as Hubble Space Telescope solar arrays, European Retrievable Carrier, and Space Shuttles. To increase our understanding of the current LEO debris environment, the Orbital Debris Program Office at NASA JSC has initiated an effort to improve and update the ORDEM96 model (Kessler et al. 1996, NASA TM-104825) utilizing the recently available data. This paper gives an overview of the new NASA orbital debris engineering model, ORDEM2000.

  6. Survey of the Current Activities in the Field of Modeling the Space Debris Environment at TU Braunschweig

    Directory of Open Access Journals (Sweden)

    André Horstmann

    2018-04-01

    Full Text Available The Institute of Space Systems at Technische Universität Braunschweig has long-term experience in the field of space debris modeling. This article reviews the current state of ongoing research in this area. Extensive activities are currently underway to update the European space debris model MASTER. In addition to updating the historical population, the future evolution of the space debris environment is also being investigated. The competencies developed within these activities are used to address current problems with regard to the possibility of an increasing number of catastrophic collisions. Related research areas include, for example, research in the field of orbit determination and the simulation of sensor systems for the acquisition and cataloging of orbital objects. In particular, the ability to provide simulated measurement data for object populations in almost all size ranges is an important prerequisite for these investigations. Some selected results on the distribution of space debris on Earth orbit are presented in terms of spatial density. Furthermore, specific fragmentation events will be discussed.

  7. Orbital Debris and Future Environment Remediation

    Science.gov (United States)

    Liou, Jer-Chyi

    2011-01-01

    This slide presentation is an overview of the historical and current orbital debris environment. Included is information about: Projected growth of the future debris population, The need for active debris removal (ADR), A grand challenge for the 21st century and The forward path

  8. An Assessment of the Current LEO Debris Environment and the Need for Active Debris Removal

    Science.gov (United States)

    Liou, Jer-Chyi

    2010-01-01

    The anti-satellite test on the Fengun-1 C weather satellite in early 2007 and the collision between Iridium 33 and Cosmos 2251 in 2009 dramatically altered the landscape of the human-made orbital debris environment in the low Earth orbit (LEO). The two events generated approximately 5500 fragments large enough to be tracked by the U.S. Space Surveillance Network. Those fragments account for more than 60% increase to the debris population in LEO. However, even before the ASAT test, model analyses already indicated that the debris population (for those larger than 10 cm) in LEO had reached a point where the population would continue to increase, due to collisions among existing objects, even without any future launches. The conclusion implies that as satellites continue to be launched and unexpected breakup events continue to occur, commonly-adopted mitigation measures will not be able to stop the collision-driven population growth. To remediate the debris environment in LEO, active debris removal must be considered. This presentation will provide an updated assessment of the debris environment after the Iridium 33/Cosmos 2251 collision, an analysis of several future environment projections based on different scenarios, and a projection of collision activities in LEO in the near future. The need to use active debris removal to stabilize future debris environment will be demonstrated and the effectiveness of various active debris removal strategies will be quantified.

  9. Sensitivity of numerical simulation models of debris flow to the rheological parameters and application in the engineering environment

    Science.gov (United States)

    Rosso, M.; Sesenna, R.; Magni, L.; Demurtas, L.; Uras, G.

    2009-04-01

    Debris flows represents serious hazards in mountainous regions. For engineers it is important to know the quantitative analysis of the flow in terms of volumes, velocities and front height, and it is significant to predict possible triggering and deposition areas. In order to predict flow and deposition behaviour, debris flows traditionally have been regarded as homogenous fluids and bulk flow behaviour that was considered to be controlled by the rheological properties of the matrix. Flow mixtures with a considerable fraction of fines particles typically show a viscoplastic flow behaviour but due to the high variability of the material composition, complex physical interactions on the particle scale and time dependent effects, no generally applicable models are at time capable to cover the full range of all possible flow types. A first category of models, mostly of academic origin, uses a rigorous methodological approach, directed to describe to the phenomenon characterizing all the main parameters that regulate the origin and the propagation of the debris flow, with detail attention to rheology. A second category, which are referred mainly to the commercial environment, has as first objective the versatility and the simplicity of use, introducing theoretical simplifications in the definition of the rheology and in the propagation of the debris flow. The physical variables connected to the rheology are often difficult to determine and involve complex procedures of calibration of the model or long and expensive campaigns of measure, whose application can turn out not suitable to the engineering environment. The rheological parameters of the debris are however to the base of the codes of calculation mainly used in commerce. The necessary data to the implementation of the model refer mainly to the dynamic viscosity, to the shear stress, to the volumetric mass and to the volumetric concentration, that are linked variables. Through the application of various

  10. Debris flows: Experiments and modelling

    Science.gov (United States)

    Turnbull, Barbara; Bowman, Elisabeth T.; McElwaine, Jim N.

    2015-01-01

    Debris flows and debris avalanches are complex, gravity-driven currents of rock, water and sediments that can be highly mobile. This combination of component materials leads to a rich morphology and unusual dynamics, exhibiting features of both granular materials and viscous gravity currents. Although extreme events such as those at Kolka Karmadon in North Ossetia (2002) [1] and Huascarán (1970) [2] strongly motivate us to understand how such high levels of mobility can occur, smaller events are ubiquitous and capable of endangering infrastructure and life, requiring mitigation. Recent progress in modelling debris flows has seen the development of multiphase models that can start to provide clues of the origins of the unique phenomenology of debris flows. However, the spatial and temporal variations that debris flows exhibit make this task challenging and laboratory experiments, where boundary and initial conditions can be controlled and reproduced, are crucial both to validate models and to inspire new modelling approaches. This paper discusses recent laboratory experiments on debris flows and the state of the art in numerical models.

  11. A Parametric Study on Using Active Debris Removal to Stabilize the Future LEO Debris Environment

    Science.gov (United States)

    Liou, J.C.

    2010-01-01

    Recent analyses of the instability of the orbital debris population in the low Earth orbit (LEO) region and the collision between Iridium 33 and Cosmos 2251 have reignited the interest in using active debris removal (ADR) to remediate the environment. There are; however, monumental technical, resources, operational, legal, and political challenges in making economically viable ADR a reality. Before a consensus on the need for ADR can be reached, a careful analysis of the effectiveness of ADR must be conducted. The goal is to demonstrate the feasibility of using ADR to preserve the future environment and to guide its implementation to maximize the benefit-cost ratio. This paper describes a comprehensive sensitivity study on using ADR to stabilize the future LEO debris environment. The NASA long-term, orbital debris evolutionary model, LEGEND, is used to quantify the effects of many key parameters. These parameters include (1) the starting epoch of ADR implementation, (2) various target selection criteria, (3) the benefits of collision avoidance maneuvers, (4) the consequence of targeting specific inclination or altitude regimes, (5) the consequence of targeting specific classes of vehicles, and (6) the timescale of removal. Additional analyses on the importance of postmission disposal and how future launches might affect the requirements to stabilize the environment are also included.

  12. Modeling the fate and transport of plastic debris in freshwaters

    OpenAIRE

    Kooi, Merel; Besseling, Ellen; Kroeze, Carolien; Wenzel, van, Annemarie P.; Koelmans, Albert A.

    2018-01-01

    Contamination with plastic debris has been recognized as one of today’s major environmental quality problems. Because most of the sources are land based, concerns are increasingly focused on the freshwater and terrestrial environment. Fate and transport models for plastic debris can complement information from measurements and will play an important role in the prospective risk assessment of plastic debris. We review the present knowledge with respect to fate and transport modeling of plastic...

  13. The Orbital Debris Problem and the Challenges for Environment Remediation

    Science.gov (United States)

    Liou, J.-C.

    2013-01-01

    Orbital debris scientists from major international space agencies, including JAXA and NASA, have worked together to predict the trend of the future environment. A summary presentation was given to the United Nations in February 2013. The orbital debris population in LEO will continue to increase. Catastrophic collisions will continue to occur every 5 to 9 years center dot To limit the growth of the future debris population and to better protect future spacecraft, active debris removal, should be considered.

  14. Modeling the fate and transport of plastic debris in freshwaters

    NARCIS (Netherlands)

    Kooi, Merel; Besseling, Ellen; Kroeze, Carolien; Wenzel, van Annemarie P.; Koelmans, Albert A.

    2018-01-01

    Contamination with plastic debris has been recognized as one of today’s major environmental quality problems. Because most of the sources are land based, concerns are increasingly focused on the freshwater and terrestrial environment. Fate and transport models for plastic debris can complement

  15. ORDEM2010 and MASTER-2009 Modeled Small Debris Population Comparison

    Science.gov (United States)

    Krisko, Paula H.; Flegel, S.

    2010-01-01

    The latest versions of the two premier orbital debris engineering models, NASA s ORDEM2010 and ESA s MASTER-2009, have been publicly released. Both models have gone through significant advancements since inception, and now represent the state-of-the-art in orbital debris knowledge of their respective agencies. The purpose of these models is to provide satellite designers/operators and debris researchers with reliable estimates of the artificial debris environment in near-Earth orbit. The small debris environment within the size range of 1 mm to 1 cm is of particular interest to both human and robotic spacecraft programs. These objects are much more numerous than larger trackable debris but are still large enough to cause significant, if not catastrophic, damage to spacecraft upon impact. They are also small enough to elude routine detection by existing observation systems (radar and telescope). Without reliable detection the modeling of these populations has always coupled theoretical origins with supporting observational data in different degrees. This paper details the 1 mm to 1 cm orbital debris populations of both ORDEM2010 and MASTER-2009; their sources (both known and presumed), current supporting data and theory, and methods of population analysis. Fluxes on spacecraft for chosen orbits are also presented and discussed within the context of each model.

  16. Debris Thermal Hydraulics Modeling of QUENCH Experiments

    International Nuclear Information System (INIS)

    Kisselev, Arcadi E.; Kobelev, Gennadii V.; Strizhov, Valerii F.; Vasiliev, Alexander D.

    2006-01-01

    Porous debris formation and behavior in QUENCH experiments (QUENCH-02, QUENCH-03) plays a considerable role and its adequate modeling is important for thermal analysis. This work is aimed to the development of a numerical module which is able to model thermal hydraulics and heat transfer phenomena occurring during the high-temperature stage of severe accident with the formation of debris region and molten pool. The original approach for debris evolution is developed from classical principles using a set of parameters including debris porosity; average particle diameter; temperatures and mass fractions of solid, liquid and gas phases; specific interface areas between different phases; effective thermal conductivity of each phase, including radiative heat conductivity; mass and energy fluxes through the interfaces. The debris model is based on the system of continuity, momentum and energy conservation equations, which consider the dynamics of volume-averaged velocities and temperatures of fluid, solid and gaseous phases of porous debris. The different mechanisms of debris formation are considered, including degradation of fuel rods according to temperature criteria, taking into consideration some correlations between rod layers thicknesses; degradation of rod layer structure due to thermal expansion of melted materials inside intact rod cladding; debris formation due to sharp temperature drop of previously melted material due to reflood; and transition to debris of material from elements lying above. The porous debris model was implemented to best estimate numerical code RATEG/SVECHA/HEFEST developed for modeling thermal hydraulics and severe accident phenomena in a reactor. The model is used for calculation of QUENCH experiments. The results obtained by the model are compared to experimental data concerning different aspects of thermal behavior: thermal hydraulics of porous debris, radiative heat transfer in a porous medium, the generalized melting and refreezing

  17. Debris mitigation techniques for petawatt-class lasers in high debris environments

    Directory of Open Access Journals (Sweden)

    Jens Schwarz

    2010-04-01

    Full Text Available This paper addresses debris mitigation techniques for two different kinds of debris sources that are found in the high-energy density community. The first debris source stems from the laser-target interaction and this debris can be mitigated by avoiding a direct line of sight to the debris source (e.g. by using a sacrificial fold mirror or by inserting a thin debris shield. Several thin film debris shields have been investigated and nitrocellulose was found to be the best suited. The second debris source originates from an external high-energy density driver or experiment. In our specific case, this is the Z accelerator, a Z-pinch machine that generates 2 MJ of x rays at 300 TW. The center section of the Z accelerator is an extremely violent environment which requires the development of novel debris mitigation approaches for backlighting with petawatt lasers. Two such approaches are presented in this paper. First, a self-closing focusing cone. In our facility, the focused beam on target is fully enclosed inside a solid focusing cone. In the first debris mitigation scenario, the last part of the cone has a “flapper” that should seal the cone when the pressure wave from the Z-pinch explosion hits it. In the second scenario, an enclosed target assembly is used, with the last part of the focusing cone connected to a “target can” which houses the laser target. The laser produced x rays for backlighting escape through a 3 mm diameter hole that is protected by an x-ray filter stack. Both techniques are discussed in detail and have been successfully tested on the Z accelerator.

  18. Development of a debris flow model in a geotechnical centrifuge

    Science.gov (United States)

    Cabrera, Miguel Angel; Wu, Wei

    2013-04-01

    Debris flows occur in three main stages. At first the initial soil mass, which rests in a rigid configuration, reaches a critic state releasing a finite mass over a failure surface. In the second stage the released mass starts being transported downhill in a dynamic motion. Segregation, erosion, entrainment, and variable channel geometry are among the more common characteristics of this stage. Finally, at the third stage the transported mass plus the mass gained or loosed during the transportation stage reach a flat and/or a wide area and its deposition starts, going back to a rigid configuration. The lack of understanding and predictability of debris flow from the traditional theoretical approaches has lead that in the last two decades the mechanics of debris flows started to be analysed around the world. Nevertheless, the validation of recent numerical advances with experimental data is required. Centrifuge modelling is an experimental tool that allows the test of natural processes under defined boundary conditions in a small scale configuration, with a good level of accuracy in comparison with a full scale test. This paper presents the development of a debris flow model in a geotechnical centrifuge focused on the second stage of the debris flow process explained before. A small scale model of an inclined flume will be developed, with laboratory instrumentation able to measure the pore pressure, normal stress, and velocity path, developed in a scaled debris flow in motion. The model aims to reproduce in a controlled environment the main parameters of debris flow motion. This work is carried under the EC 7th Framework Programme as part of the MUMOLADE project. The dataset and data-analysis obtained from the tests will provide a qualitative description of debris flow motion-mechanics and be of valuable information for MUMOLADE co-researchers and for the debris flow research community in general.

  19. GENERALIZED VISCOPLASTIC MODELING OF DEBRIS FLOW.

    Science.gov (United States)

    Chen, Cheng-lung

    1988-01-01

    The earliest model developed by R. A. Bagnold was based on the concept of the 'dispersive' pressure generated by grain collisions. Some efforts have recently been made by theoreticians in non-Newtonian fluid mechanics to modify or improve Bagnold's concept or model. A viable rheological model should consist both of a rate-independent part and a rate-dependent part. A generalized viscoplastic fluid (GVF) model that has both parts as well as two major rheological properties (i. e. , the normal stress effect and soil yield criterion) is shown to be sufficiently accurate, yet practical for general use in debris-flow modeling. In fact, Bagnold's model is found to be only a particular case of the GVF model. analytical solutions for (steady) uniform debris flows in wide channels are obtained from the GVF model based on Bagnold's simplified assumption of constant grain concentration.

  20. Debris Dispersion Model Using Java 3D

    Science.gov (United States)

    Thirumalainambi, Rajkumar; Bardina, Jorge

    2004-01-01

    This paper describes web based simulation of Shuttle launch operations and debris dispersion. Java 3D graphics provides geometric and visual content with suitable mathematical model and behaviors of Shuttle launch. Because the model is so heterogeneous and interrelated with various factors, 3D graphics combined with physical models provides mechanisms to understand the complexity of launch and range operations. The main focus in the modeling and simulation covers orbital dynamics and range safety. Range safety areas include destruct limit lines, telemetry and tracking and population risk near range. If there is an explosion of Shuttle during launch, debris dispersion is explained. The shuttle launch and range operations in this paper are discussed based on the operations from Kennedy Space Center, Florida, USA.

  1. An Overview of the Orbital Debris and Meteoroid Environments, Their Effects on Spacecraft, and What Can We Do About It?

    Science.gov (United States)

    Matney, Mark

    2017-01-01

    Because of the high speeds needed for orbital space flight, hypervelocity impacts with objects in space are a constant risk to spacecraft. This includes natural debris - meteoroids - and the debris remnants of our own activities in space. A number of space surveillance assets are used to measure and track spacecraft, used upper stages, and breakup debris. However, much of the debris and meteoroids encountered by spacecraft in Earth orbit is not easily measured or tracked. For every man-made object that we can track, there are hundreds of small debris that are too small to be tracked but still large enough to damage spacecraft. In addition, even if we knew today's environment with perfect knowledge, the debris environment is dynamic and would change tomorrow. This means that much of the risk from both meteoroids and anthropogenic debris is statistical in nature. NASA uses and maintains a number of instruments to statistically monitor the meteoroid and orbital debris environments, and uses this information to compute statistical models for use by spacecraft designers and operators. Because orbital debris is a result of human activities, NASA has led the US government in formulating national and international strategies that space users can employ to limit the growth of debris in the future. This talk will summarize the history and current state of meteoroid and space debris measurements and modeling, how the environment influences spacecraft design and operations, how we are designing the experiments of tomorrow to improve our knowledge, and how we are working internationally to preserve the space environment for the future.

  2. Modelling debris flows down general channels

    Directory of Open Access Journals (Sweden)

    S. P. Pudasaini

    2005-01-01

    Full Text Available This paper is an extension of the single-phase cohesionless dry granular avalanche model over curved and twisted channels proposed by Pudasaini and Hutter (2003. It is a generalisation of the Savage and Hutter (1989, 1991 equations based on simple channel topography to a two-phase fluid-solid mixture of debris material. Important terms emerging from the correct treatment of the kinematic and dynamic boundary condition, and the variable basal topography are systematically taken into account. For vanishing fluid contribution and torsion-free channel topography our new model equations exactly degenerate to the previous Savage-Hutter model equations while such a degeneration was not possible by the Iverson and Denlinger (2001 model, which, in fact, also aimed to extend the Savage and Hutter model. The model equations of this paper have been rigorously derived; they include the effects of the curvature and torsion of the topography, generally for arbitrarily curved and twisted channels of variable channel width. The equations are put into a standard conservative form of partial differential equations. From these one can easily infer the importance and influence of the pore-fluid-pressure distribution in debris flow dynamics. The solid-phase is modelled by applying a Coulomb dry friction law whereas the fluid phase is assumed to be an incompressible Newtonian fluid. Input parameters of the equations are the internal and bed friction angles of the solid particles, the viscosity and volume fraction of the fluid, the total mixture density and the pore pressure distribution of the fluid at the bed. Given the bed topography and initial geometry and the initial velocity profile of the debris mixture, the model equations are able to describe the dynamics of the depth profile and bed parallel depth-averaged velocity distribution from the initial position to the final deposit. A shock capturing, total variation diminishing numerical scheme is implemented to

  3. Accumulation and fragmentation of plastic debris in global environments.

    Science.gov (United States)

    Barnes, David K A; Galgani, Francois; Thompson, Richard C; Barlaz, Morton

    2009-07-27

    One of the most ubiquitous and long-lasting recent changes to the surface of our planet is the accumulation and fragmentation of plastics. Within just a few decades since mass production of plastic products commenced in the 1950s, plastic debris has accumulated in terrestrial environments, in the open ocean, on shorelines of even the most remote islands and in the deep sea. Annual clean-up operations, costing millions of pounds sterling, are now organized in many countries and on every continent. Here we document global plastics production and the accumulation of plastic waste. While plastics typically constitute approximately 10 per cent of discarded waste, they represent a much greater proportion of the debris accumulating on shorelines. Mega- and macro-plastics have accumulated in the highest densities in the Northern Hemisphere, adjacent to urban centres, in enclosed seas and at water convergences (fronts). We report lower densities on remote island shores, on the continental shelf seabed and the lowest densities (but still a documented presence) in the deep sea and Southern Ocean. The longevity of plastic is estimated to be hundreds to thousands of years, but is likely to be far longer in deep sea and non-surface polar environments. Plastic debris poses considerable threat by choking and starving wildlife, distributing non-native and potentially harmful organisms, absorbing toxic chemicals and degrading to micro-plastics that may subsequently be ingested. Well-established annual surveys on coasts and at sea have shown that trends in mega- and macro-plastic accumulation rates are no longer uniformly increasing: rather stable, increasing and decreasing trends have all been reported. The average size of plastic particles in the environment seems to be decreasing, and the abundance and global distribution of micro-plastic fragments have increased over the last few decades. However, the environmental consequences of such microscopic debris are still poorly

  4. Modeling the fate and transport of plastic debris in fresh waters. Review and guidance

    NARCIS (Netherlands)

    Kooi, M.; Besseling, E.; Kroeze, C.; Wenzel, van A.P.; Koelmans, A.A.

    2018-01-01

    Contamination with plastic debris has been recognized as one of today’s major environmental quality problems. Because most of the sources are land based, concerns are increasingly focused on the freshwater and terrestrial environment. Fate and transport models for plastic debris can complement

  5. New advances for modelling the debris avalanches

    Science.gov (United States)

    Cuomo, Sabatino; Cascini, Leonardo; Pastor, Manuel; Castorino, Giuseppe Claudio

    2013-04-01

    Flow-like landslides are a major global hazard and they occur worldwide causing a large number of casualties, significant structural damages to property and infrastructures as well as economic losses. When involving open slopes, these landslides often occur in triangular source areas where initial slides turn into avalanches through further failures and/or eventual soil entrainment. This paper deals with the numerical modelling of the propagation stage of debris avalanches which provides information such as the propagation pattern of the mobilized material, its velocity, thickness and run-out distance. In the paper, a "depth integrated" model is used which allows: i) adequately taking into account the irregular topography of real slopes which greatly affect the propagation stage and ii) using a less time consuming model than fully 3D approaches. The used model is named "GeoFlow_SPH" and it was formerly applied to theoretical, experimental and real case histories (Pastor et al., 2009; Cascini et al., 2012). In this work the behavior of debris avalanches is analyzed with special emphasis on the apical angle, one of the main features of this type of landslide, in relation to soil rheology, hillslope geometry and features of triggering area. Furthermore, the role of erosion has been investigated with reference to the uppermost parts of open slopes with a different steepness. These analyses are firstly carried out for simplified benchmark slopes, using both water-like materials (with no shear strength) and debris type materials. Then, three important case studies of Campania region (Cervinara, Nocera Inferiore e Sarno) are analyzed where debris avalanches involved pyroclastic soils originated from the eruptive products of Vesusius volcano. The results achieved for both benchmark slopes and real case histories outline the key role played by the erosion on the whole propagation stage of debris avalanches. The results are particularly satisfactory since they indicate the

  6. Accumulation and fragmentation of plastic debris in global environments

    OpenAIRE

    Barnes, David K. A.; Galgani, Francois; Thompson, Richard C.; Barlaz, Morton

    2009-01-01

    One of the most ubiquitous and long-lasting recent changes to the surface of our planet is the accumulation and fragmentation of plastics. Within just a few decades since mass production of plastic products commenced in the 1950s, plastic debris has accumulated in terrestrial environments, in the open ocean, on shorelines of even the most remote islands and in the deep sea. Annual clean-up operations, costing millions of pounds sterling, are now organized in many countries and on every contin...

  7. The Near-Earth Orbital Debris Problem and the Challenges for Environment Remediation

    Science.gov (United States)

    Liou, Jer-Chyi

    2012-01-01

    The near-Earth space environment has been gradually polluted with orbital debris (OD) since the beginning of space activities 55 years ago. Although this problem has been known to the research community for decades, the public was, in general, unaware of the issue until the anti-satellite test conducted by China in 2007 and the collision between Cosmos 2251 and the operational Iridium 33 in 2009. The latter also underlined the potential of an ongoing collision cascade effect (the "Kessler Syndrome") in the low Earth orbit (LEO, the region below 2000 km altitude). Recent modeling results have indicated that mitigation measures commonly adopted by the international space community will be insufficient to stabilize the LEO debris population. To better limit the OD population increase, more aggressive actions must be considered. There are three options for OD environment remediation-removal of large/massive intact objects to address the root cause of the OD population growth problem, removal of 5-mm-to-1 cm debris to mitigate the main mission-ending threats for the majority of operational spacecraft, and prevention of major debris-generating collisions as a temporary means to slow down the OD population increase. The technology, engineering, and cost challenges to carry out any of these three options are monumental. It will require innovative ideas, game-changing technologies, and major collaborations at the international level to address the OD problem and preserve the near-Earth environment for future generations.

  8. A Parametric Study on Using Active Debris Removal for LEO Environment Remediation

    Science.gov (United States)

    2010-01-01

    Recent analyses on the instability of the orbital debris population in the low Earth orbit (LEO) region and the collision between Iridium 33 and Cosmos 2251 have reignited the interest in using active debris removal (ADR) to remediate the environment. There are; however, monumental technical, resource, operational, legal, and political challenges in making economically viable ADR a reality. Before a consensus on the need for ADR can be reached, a careful analysis of its effectiveness must be conducted. The goal is to demonstrate the need and feasibility of using ADR to better preserve the future environment and to guide its implementation to maximize the benefit-to-cost ratio. This paper describes a new sensitivity study on using ADR to stabilize the future LEO debris environment. The NASA long-term orbital debris evolutionary model, LEGEND, is used to quantify the effects of several key parameters, including target selection criteria/constraints and the starting epoch of ADR implementation. Additional analyses on potential ADR targets among the currently existing satellites and the benefits of collision avoidance maneuvers are also included.

  9. ORDEM 3.0 and MASTER-2009 Modeled Small Debris Population Comparison

    Science.gov (United States)

    Krisko, P. H.; Flegel, S.

    2014-01-01

    The latest versions of the two premier orbital debris engineering models, NASA's ORDEM 3.0 and ESA's MASTER-2009, have been publically released. Both models have gone through significant advancements since inception, and now represent the state-of-the-art in orbital debris knowledge of their respective agencies. The purpose of these models is to provide satellite designers/operators and debris researchers with reliable estimates of the artificial debris environment in low Earth orbit (LEO) to geosynchronous orbit (GEO). The small debris environment within the size range of 1 mm to 1 cm is of particular interest to both human and robotic spacecraft programs, particularly in LEO. These objects are much more numerous than larger trackable debris and can have enough momentum to cause significant, if not catastrophic, damage to spacecraft upon impact. They are also small enough to elude routine detection by existing observation systems (radar and telescope). Without reliable detection the modeling of these populations has always coupled theoretical origins with supporting observational data in different degrees. In this paper, we present and detail the 1 mm to 1 cm orbital debris populations from both ORDEM 3.0 and MASTER-2009 in LEO. We review population categories: particle sources for MASTER-2009, particle densities for ORDEM 3.0. We describe data sources and their uses, and supporting models. Fluxes on spacecraft for chosen orbits are also presented and discussed within the context of each model.

  10. Monitoring the abundance of plastic debris in the marine environment

    OpenAIRE

    Ryan, Peter G.; Moore, Charles J.; van Franeker, Jan A.; Moloney, Coleen L.

    2009-01-01

    Plastic debris has significant environmental and economic impacts in marine systems. Monitoring is crucial to assess the efficacy of measures implemented to reduce the abundance of plastic debris, but it is complicated by large spatial and temporal heterogeneity in the amounts of plastic debris and by our limited understanding of the pathways followed by plastic debris and its long-term fate. To date, most monitoring has focused on beach surveys of stranded plastics and other litter. Infreque...

  11. Monitoring the abundance of plastic debris in the marine environment

    NARCIS (Netherlands)

    Ryan, P.G.; Moore, C.J. C.J.; Franeker, van J.A.; Moloney, C.L.

    2009-01-01

    Plastic debris has significant environmental and economic impacts in marine systems. Monitoring is crucial to assess the efficacy of measures implemented to reduce the abundance of plastic debris, but it is complicated by large spatial and temporal heterogeneity in the amounts of plastic debris and

  12. A computational model for assessing high-velocity debris impact in space applications

    Science.gov (United States)

    Bergh, M.; Garcia, V.

    2017-07-01

    Man-made space debris is dominating the background meteorite environment with a growing debris population leading to increased collision risks for satellites, especially in the low Earth orbit and geostationary orbit protected environments. Here we present a computational model for estimating the effect of hypervelocity impact from debris particles on non-shielded propellant and pressurant tanks. Eulerian hydrocode simulation is utilised to model firstly penetration and shock wave formation in the propellant and secondly subsequent detonation wave propagation and interaction with the tank wall. Furthermore, reactive molecular dynamics is used to estimate the risk of detonation in a liquid hydrazine layer. We present simulations of a 3.5 mm aluminium spherical debris particle at a velocity of 14 km/s relative to a hydrazine tank. We find that the degree of damage is strongly dependent on tank temperature and hence on the satellite thermal configuration at its end of life.

  13. Modeling of LEO Orbital Debris Populations in Centimeter and Millimeter Size Regimes

    Science.gov (United States)

    Xu, Y.-L.; Hill, . M.; Horstman, M.; Krisko, P. H.; Liou, J.-C.; Matney, M.; Stansbery, E. G.

    2010-01-01

    The building of the NASA Orbital Debris Engineering Model, whether ORDEM2000 or its recently updated version ORDEM2010, uses as its foundation a number of model debris populations, each truncated at a minimum object-size ranging from 10 micron to 1 m. This paper discusses the development of the ORDEM2010 model debris populations in LEO (low Earth orbit), focusing on centimeter (smaller than 10 cm) and millimeter size regimes. Primary data sets used in the statistical derivation of the cm- and mm-size model populations are from the Haystack radar operated in a staring mode. Unlike cataloged objects of sizes greater than approximately 10 cm, ground-based radars monitor smaller-size debris only in a statistical manner instead of tracking every piece. The mono-static Haystack radar can detect debris as small as approximately 5 mm at moderate LEO altitudes. Estimation of millimeter debris populations (for objects smaller than approximately 6 mm) rests largely on Goldstone radar measurements. The bi-static Goldstone radar can detect 2- to 3-mm objects. The modeling of the cm- and mm-debris populations follows the general approach to developing other ORDEM2010-required model populations for various components and types of debris. It relies on appropriate reference populations to provide necessary prior information on the orbital structures and other important characteristics of the debris objects. NASA's LEO-to-GEO Environment Debris (LEGEND) model is capable of furnishing such reference populations in the desired size range. A Bayesian statistical inference process, commonly adopted in ORDEM2010 model-population derivations, changes a priori distribution into a posteriori distribution and thus refines the reference populations in terms of data. This paper describes key elements and major steps in the statistical derivations of the cm- and mm-size debris populations and presents results. Due to lack of data for near 1-mm sizes, the model populations of 1- to 3.16-mm

  14. Evasive Maneuvers in Space Debris Environment and Technological Parameters

    Directory of Open Access Journals (Sweden)

    Antônio D. C. Jesus

    2012-01-01

    Full Text Available We present a study of collisional dynamics between space debris and an operational vehicle in LEO. We adopted an approach based on the relative dynamics between the objects on a collisional course and with a short warning time and established a semianalytical solution for the final trajectories of these objects. Our results show that there are angular ranges in 3D, in addition to the initial conditions, that favor the collisions. These results allowed the investigation of a range of technological parameters for the spacecraft (e.g., fuel reserve that allow a safe evasive maneuver (e.g., time available for the maneuver. The numerical model was tested for different values of the impact velocity and relative distance between the approaching objects.

  15. USA Space Debris Environment, Operations, and Research Updates

    Science.gov (United States)

    Liou, J.-C.

    2018-01-01

    Space Missions in 2017 Earth Satellite Population Collision Avoidance Maneuvers Post mission Disposal of U.S.A. Spacecraft Space Situational Awareness (SSA) and the Space Debris Sensor (SDS) A total of 86 space launches placed more than 400 spacecraft into Earth orbits during 2017, following the trend of increase over the past decade NASA has established conjunction assessment processes for its human spaceflight and uncrewed spacecraft to avoid accidental collisions with objects tracked by the U.S. Space Surveillance Network - NASA also assists other U.S. government spacecraft owners with conjunction assessments and subsequent maneuvers The ISS has conducted 25 debris collision avoidance maneuvers since 1999 - None in 2016-2017, but an ISS visiting vehicle had one collision avoidance maneuver in 2017 During 2017 NASA executed or assisted in the execution of 21 collision avoidance maneuvers by uncrewed spacecraft - Four maneuvers were conducted to avoid debris from Fengyun-1C - Two maneuvers were conducted to avoid debris from the collision of Cosmos 2251 and Iridium 33 - One maneuver was conducted to avoid the ISS NASA has established conjunction assessment processes for its human spaceflight and uncrewed spacecraft to avoid accidental collisions with objects tracked by the U.S. Space Surveillance Network - NASA also assists other U.S. government spacecraft owners with conjunction assessments and subsequent maneuvers The ISS has conducted 25 debris collision avoidance maneuvers since 1999 - None in 2016-2017, but an ISS visiting vehicle had one collision avoidance maneuver in 2017 During 2017 NASA executed or assisted in the execution of 21 collision avoidance maneuvers by uncrewed spacecraft - Four maneuvers were conducted to avoid debris from Fengyun-1C - Two maneuvers were conducted to avoid debris from the collision of Cosmos 2251 and Iridium 33 The 2014-15 NASA Engineering and Safety Center (NESC) study on the micrometeoroid and orbital debris (MMOD

  16. Modelling untrackable orbital debris associated with a tracked space debris cloud.

    Science.gov (United States)

    Culp, R. D.; Madler, R. A.

    A computer model, including both the trackable and untrackable size regimes, has been developed to simulate several types of satellite fragmentations. These particle swarms are then propagated using a perturbation model to predict the collision hazard associated with the entire swarm. The results of this study will aid in estimating the long term hazard posed by debris particles to operating satellites and space operations.

  17. Benthic plastic debris in marine and fresh water environments.

    Science.gov (United States)

    Corcoran, Patricia L

    2015-08-01

    This review provides a discussion of the published literature concerning benthic plastic debris in ocean, sea, lake, estuary and river bottoms throughout the world. Although numerous investigations of shoreline, surface and near-surface plastic debris provide important information on plastic types, distribution, accumulation, and degradation, studies of submerged plastic debris have been sporadic in the past and have become more prominent only recently. The distribution of benthic debris is controlled mainly by combinations of urban proximity and its association with fishing-related activities, geomorphology, hydrological conditions, and river input. High density plastics, biofouled products, polymers with mineral fillers or adsorbed minerals, and plastic-metal composites all have the potential to sink. Once deposited on the bottoms of water basins and channels, plastics are shielded from UV light, thus slowing the degradation process significantly. Investigations of the interactions between benthic plastic debris and bottom-dwelling organisms will help shed light on the potential dangers of submerged plastic litter.

  18. Monitoring the abundance of plastic debris in the marine environment.

    Science.gov (United States)

    Ryan, Peter G; Moore, Charles J; van Franeker, Jan A; Moloney, Coleen L

    2009-07-27

    Plastic debris has significant environmental and economic impacts in marine systems. Monitoring is crucial to assess the efficacy of measures implemented to reduce the abundance of plastic debris, but it is complicated by large spatial and temporal heterogeneity in the amounts of plastic debris and by our limited understanding of the pathways followed by plastic debris and its long-term fate. To date, most monitoring has focused on beach surveys of stranded plastics and other litter. Infrequent surveys of the standing stock of litter on beaches provide crude estimates of debris types and abundance, but are biased by differential removal of litter items by beachcombing, cleanups and beach dynamics. Monitoring the accumulation of stranded debris provides an index of debris trends in adjacent waters, but is costly to undertake. At-sea sampling requires large sample sizes for statistical power to detect changes in abundance, given the high spatial and temporal heterogeneity. Another approach is to monitor the impacts of plastics. Seabirds and other marine organisms that accumulate plastics in their stomachs offer a cost-effective way to monitor the abundance and composition of small plastic litter. Changes in entanglement rates are harder to interpret, as they are sensitive to changes in population sizes of affected species. Monitoring waste disposal on ships and plastic debris levels in rivers and storm-water runoff is useful because it identifies the main sources of plastic debris entering the sea and can direct mitigation efforts. Different monitoring approaches are required to answer different questions, but attempts should be made to standardize approaches internationally.

  19. Monitoring the abundance of plastic debris in the marine environment

    Science.gov (United States)

    Ryan, Peter G.; Moore, Charles J.; van Franeker, Jan A.; Moloney, Coleen L.

    2009-01-01

    Plastic debris has significant environmental and economic impacts in marine systems. Monitoring is crucial to assess the efficacy of measures implemented to reduce the abundance of plastic debris, but it is complicated by large spatial and temporal heterogeneity in the amounts of plastic debris and by our limited understanding of the pathways followed by plastic debris and its long-term fate. To date, most monitoring has focused on beach surveys of stranded plastics and other litter. Infrequent surveys of the standing stock of litter on beaches provide crude estimates of debris types and abundance, but are biased by differential removal of litter items by beachcombing, cleanups and beach dynamics. Monitoring the accumulation of stranded debris provides an index of debris trends in adjacent waters, but is costly to undertake. At-sea sampling requires large sample sizes for statistical power to detect changes in abundance, given the high spatial and temporal heterogeneity. Another approach is to monitor the impacts of plastics. Seabirds and other marine organisms that accumulate plastics in their stomachs offer a cost-effective way to monitor the abundance and composition of small plastic litter. Changes in entanglement rates are harder to interpret, as they are sensitive to changes in population sizes of affected species. Monitoring waste disposal on ships and plastic debris levels in rivers and storm-water runoff is useful because it identifies the main sources of plastic debris entering the sea and can direct mitigation efforts. Different monitoring approaches are required to answer different questions, but attempts should be made to standardize approaches internationally. PMID:19528052

  20. Recent advances in modeling landslides and debris flows

    CERN Document Server

    2015-01-01

    Landslides and debris flows belong to the most dangerous natural hazards in many parts of the world. Despite intensive research, these events continue to result in human suffering, property losses, and environmental degradation every year. Better understanding of the mechanisms and processes of landslides and debris flows will help make reliable predictions, develop mitigation strategies and reduce vulnerability of infrastructure. This book presents contributions to the workshop on Recent Developments in the Analysis, Monitoring and Forecast of Landslides and Debris Flow, in Vienna, Austria, September 9, 2013. The contributions cover a broad spectrum of topics from material behavior, physical modelling over numerical simulation to applications and case studies. The workshop is a joint event of three research projects funded by the European Commission within the 7th Framework Program: MUMOLADE (Multiscale modelling of landslides and debris flows, www.mumolade.com), REVENUES (Numerical Analysis of Slopes with V...

  1. Sensitivity Analysis of Launch Vehicle Debris Risk Model

    Science.gov (United States)

    Gee, Ken; Lawrence, Scott L.

    2010-01-01

    As part of an analysis of the loss of crew risk associated with an ascent abort system for a manned launch vehicle, a model was developed to predict the impact risk of the debris resulting from an explosion of the launch vehicle on the crew module. The model consisted of a debris catalog describing the number, size and imparted velocity of each piece of debris, a method to compute the trajectories of the debris and a method to calculate the impact risk given the abort trajectory of the crew module. The model provided a point estimate of the strike probability as a function of the debris catalog, the time of abort and the delay time between the abort and destruction of the launch vehicle. A study was conducted to determine the sensitivity of the strike probability to the various model input parameters and to develop a response surface model for use in the sensitivity analysis of the overall ascent abort risk model. The results of the sensitivity analysis and the response surface model are presented in this paper.

  2. Numerical modelling of floating debris in the world's oceans.

    Science.gov (United States)

    Lebreton, L C-M; Greer, S D; Borrero, J C

    2012-03-01

    A global ocean circulation model is coupled to a Lagrangian particle tracking model to simulate 30 years of input, transport and accumulation of floating debris in the world ocean. Using both terrestrial and maritime inputs, the modelling results clearly show the formation of five accumulation zones in the subtropical latitudes of the major ocean basins. The relative size and concentration of each clearly illustrate the dominance of the accumulation zones in the northern hemisphere, while smaller seas surrounded by densely populated areas are also shown to have a high concentration of floating debris. We also determine the relative contribution of different source regions to the total amount of material in a particular accumulation zone. This study provides a framework for describing the transport, distribution and accumulation of floating marine debris and can be continuously updated and adapted to assess scenarios reflecting changes in the production and disposal of plastic worldwide. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. An example of debris-flows hazard modeling using GIS

    Directory of Open Access Journals (Sweden)

    L. Melelli

    2004-01-01

    Full Text Available We present a GIS-based model for predicting debris-flows occurrence. The availability of two different digital datasets and the use of a Digital Elevation Model (at a given scale have greatly enhanced our ability to quantify and to analyse the topography in relation to debris-flows. In particular, analysing the relationship between debris-flows and the various causative factors provides new understanding of the mechanisms. We studied the contact zone between the calcareous basement and the fluvial-lacustrine infill adjacent northern area of the Terni basin (Umbria, Italy, and identified eleven basins and corresponding alluvial fans. We suggest that accumulations of colluvium in topographic hollows, whatever the sources might be, should be considered potential debris-flow source areas. In order to develop a susceptibility map for the entire area, an index was calculated from the number of initiation locations in each causative factor unit divided by the areal extent of that unit within the study area. This index identifies those units that produce the most debris-flows in each Representative Elementary Area (REA. Finally, the results are presented with the advantages and the disadvantages of the approach, and the need for further research.

  4. The affect of a clearcut environment on woody debris respiration rate dynamics, Harvard Forest, Massachusetts

    Science.gov (United States)

    Vanderhoof, M. K.; Williams, C. L.

    2011-12-01

    At an ecosystem scale, the distribution of carbon is largely a function of stand development and disturbance processes. Clearcut logging remains a common practice both in the United States and globally and typically results in elevated storage of carbon in onsite woody debris and detritus. The residence time and decomposition rate of this woody debris and detritus will affect the rate of CO2 efflux to the atmosphere and thus affect the long term consequences of such disturbances on carbon flux and storage. The removal of a forest canopy also affects a site's microclimate including the albedo, air temperature, air humidity, as well as soil temperature and moisture, many of the same factors that affect the rate of woody debris decomposition. Thus it could be expected that differences in woody debris characteristics (e.g. size, abundance, state of decay), as well as differences in microclimate, between mature and recently clearcut forest sites, would result in differences in piece and site-level woody debris decomposition rates. Although woody debris stocks post-harvest have been well characterized, few studies have explored post-disturbance woody debris respiration rates, which directly measures carbon emissions from woody debris, distinguishing decomposition from mass loss due to fragmentation or leaching. This study addressed the question: does a clearcut environment in a temperate forest affect the rate of decomposition of coarse woody debris? The rate of respiration of downed spruce logs were repeatedly measured in-situ using an LI-6250 gas analyzer in Harvard Forest, Petersham, Massachusetts. Treatments included clear-cut, shaded clear-cut, mature spruce stand, and transfer (from clearcut to spruce stand). Gas analyzer measurements were accompanied by measurements of log temperature and percent water, soil temperature, moisture and pH, as well as light levels, air temperature and humidity to determine dominant drivers of respiration rates.

  5. Modeling the long-term evolution of space debris

    Science.gov (United States)

    Nikolaev, Sergei; De Vries, Willem H.; Henderson, John R.; Horsley, Matthew A.; Jiang, Ming; Levatin, Joanne L.; Olivier, Scot S.; Pertica, Alexander J.; Phillion, Donald W.; Springer, Harry K.

    2017-03-07

    A space object modeling system that models the evolution of space debris is provided. The modeling system simulates interaction of space objects at simulation times throughout a simulation period. The modeling system includes a propagator that calculates the position of each object at each simulation time based on orbital parameters. The modeling system also includes a collision detector that, for each pair of objects at each simulation time, performs a collision analysis. When the distance between objects satisfies a conjunction criterion, the modeling system calculates a local minimum distance between the pair of objects based on a curve fitting to identify a time of closest approach at the simulation times and calculating the position of the objects at the identified time. When the local minimum distance satisfies a collision criterion, the modeling system models the debris created by the collision of the pair of objects.

  6. On the influence of debris in glacier melt modelling: a new temperature-index model accounting for the debris thickness feedback

    Science.gov (United States)

    Carenzo, Marco; Mabillard, Johan; Pellicciotti, Francesca; Reid, Tim; Brock, Ben; Burlando, Paolo

    2013-04-01

    The increase of rockfalls from the surrounding slopes and of englacial melt-out material has led to an increase of the debris cover extent on Alpine glaciers. In recent years, distributed debris energy-balance models have been developed to account for the melt rate enhancing/reduction due to a thin/thick debris layer, respectively. However, such models require a large amount of input data that are not often available, especially in remote mountain areas such as the Himalaya. Some of the input data such as wind or temperature are also of difficult extrapolation from station measurements. Due to their lower data requirement, empirical models have been used in glacier melt modelling. However, they generally simplify the debris effect by using a single melt-reduction factor which does not account for the influence of debris thickness on melt. In this paper, we present a new temperature-index model accounting for the debris thickness feedback in the computation of melt rates at the debris-ice interface. The empirical parameters (temperature factor, shortwave radiation factor, and lag factor accounting for the energy transfer through the debris layer) are optimized at the point scale for several debris thicknesses against melt rates simulated by a physically-based debris energy balance model. The latter has been validated against ablation stake readings and surface temperature measurements. Each parameter is then related to a plausible set of debris thickness values to provide a general and transferable parameterization. The new model is developed on Miage Glacier, Italy, a debris cover glacier in which the ablation area is mantled in near-continuous layer of rock. Subsequently, its transferability is tested on Haut Glacier d'Arolla, Switzerland, where debris is thinner and its extension has been seen to expand in the last decades. The results show that the performance of the new debris temperature-index model (DETI) in simulating the glacier melt rate at the point scale

  7. Statistical learning modeling method for space debris photometric measurement

    Science.gov (United States)

    Sun, Wenjing; Sun, Jinqiu; Zhang, Yanning; Li, Haisen

    2016-03-01

    Photometric measurement is an important way to identify the space debris, but the present methods of photometric measurement have many constraints on star image and need complex image processing. Aiming at the problems, a statistical learning modeling method for space debris photometric measurement is proposed based on the global consistency of the star image, and the statistical information of star images is used to eliminate the measurement noises. First, the known stars on the star image are divided into training stars and testing stars. Then, the training stars are selected as the least squares fitting parameters to construct the photometric measurement model, and the testing stars are used to calculate the measurement accuracy of the photometric measurement model. Experimental results show that, the accuracy of the proposed photometric measurement model is about 0.1 magnitudes.

  8. PRESENT STATUS OF RESEARCH IN DEBRIS FLOW MODELING.

    Science.gov (United States)

    Chen, Cheng-lung

    1985-01-01

    A viable rheological model should consist of both a time-independent part and a time-dependent part. A generalized viscoplastic fluid model that has both parts as well as two major rheological properties (i. e. , the normal stress effect and soil yield criteria) is shown to be sufficiently accurate, yet practical, for general use in debris flow modeling. Other rheological models, such as the Bingham plastic fluid model and the so-called Coulomb-viscous model, are compared in terms of the generalized viscoplastic fluid model.

  9. Experimental Setup to Assess Blast and Penetration-Induced Secondary Debris in a Military Operations in Urban Terrain (MOUT) Environment

    Science.gov (United States)

    2015-11-01

    in a Military Operations in Urban Terrain (MOUT) Environment by Paul S Duvall Approved for public release; distribution...Research Laboratory Experimental Setup to Assess Blast and Penetration-Induced Secondary Debris in a Military Operations in Urban Terrain...Induced Secondary Debris in a Military Operations in Urban Terrain (MOUT) Environment 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  10. SCDAP/RELAP5 Modeling of Heat Transfer and Flow Losses in Lower Head Porous Debris

    International Nuclear Information System (INIS)

    Coryell, E.W.; Siefken, L.J.; Paik, S.

    1998-01-01

    Designs are described for implementing models for calculating the heat transfer and flow losses in porous debris in the lower head of a reactor vessel. The COUPLE model in SCDAP/RELAP5 represents both the porous and non-porous debris that results from core material slumping into the lower head. Currently, the COUPLE model has the capability to model convective and radiative heat transfer from the surfaces of non-porous debris in a detailed manner and to model only in a simplistic manner the heat transfer from porous debris. In order to advance beyond the simplistic modeling for porous debris, designs are developed for detailed calculations of heat transfer and flow losses in porous debris. Correlations are identified for convective heat transfer in porous debris for the following modes of heat transfer; (1) forced convection to liquid, (2) forced convection to gas, (3) nucleate boiling, (4) transition boiling, and (5) film boiling. Interphase heat transfer is modeled in an approximate manner. A design is also described for implementing a model of heat transfer by radiation from debris to the interstitial fluid. A design is described for implementation of models for flow losses and interphase drag in porous debris. Since the models for heat transfer and flow losses in porous debris in the lower head are designed for general application, a design is also described for implementation of these models to the analysis of porous debris in the core region. A test matrix is proposed for assessing the capability of the implemented models to calculate the heat transfer and flow losses in porous debris. The implementation of the models described in this report is expected to improve the COUPLE code calculation of the temperature distribution in porous debris and in the lower head that supports the debris. The implementation of these models is also expected to improve the calculation of the temperature and flow distribution in porous debris in the core region

  11. The Impact of New Trends in Satellite Launches on Orbital Debris Environment

    Science.gov (United States)

    Karacalioglu, Arif Goktug; Stupl, Jan

    2016-01-01

    their desired orbits beyond the restrictions of the launch vehicle used. These near future orbital injection technologies are also covered in the developed scenario. Using the above-mentioned background information, this study aims to examine how the orbital debris environment will be affected from the new dynamics of the emerging space markets. We developed a simulation tool that is capable of propagating the objects in a given deployment scenario with variable-sized time-steps as small as one second. Over the course of the run, the software also detects collisions; additional debris objects are then created according to the NASA breakup model and are fed back into the simulation framework. Examining the simulation results, the total number of particles to accumulate in different orbits can be monitored and the number of conjunctions can be tracked to assess the collision risks. The simulation makes it possible to follow the short- and long-term effects of a particular satellite or constellation on the space environment. Likewise, the effects of changes in the debris environment on a particular satellite or constellation can be evaluated. It is authors hope that the results of this paper and further utilization of the developed simulation tool will assist in the investigation of more accurate deorbiting metrics to replace the generic 25-year disposal guidelines, as well as to guide future launches toward more sustainable and safe orbits.

  12. Plastic debris in the coastal environment: The invincible threat? Abundance of buried plastic debris on Malaysian beaches.

    Science.gov (United States)

    Fauziah, S H; Liyana, I A; Agamuthu, P

    2015-09-01

    Studies on marine debris have gained worldwide attention since many types of debris have found their way into the food chain of higher organisms. Thus, it is crucial that more focus is given to this area in order to curb contaminations in sea food. This study was conducted to quantify plastic debris buried in sand at selected beaches in Malaysia. Marine debris was identified according to size range and distribution, and this information was related to preventive actions to improve marine waste issues. For the purpose of this study, comparison of plastic waste abundance between a recreational beach and fish-landing beaches was also carried out, since the different beach types represent different activities that produce debris. Six beaches along the Malaysian coastline were selected for this study. The plastic types in this study were related to the functions of the beach. While recreational beaches have abundant quantities of plastic film, foamed plastic including polystyrene, and plastic fragment, fish-landing beaches accumulated line and foamed plastic. A total of 2542 pieces (265.30 g m(-2)) of small plastic debris were collected from all six beaches, with the highest number from Kuala Terengganu, at 879 items m(-2) on Seberang Takir Beach, followed by Batu Burok Beach with 780 items m(-2). Findings from studies of Malaysian beaches have provided a clearer understanding of the distribution of plastic debris. This demonstrates that commitments and actions, such as practices of the 'reduce, reuse, recycle' (3R) approach, supporting public awareness programmes and beach clean-up activities, are essential in order to reduce and prevent plastic debris pollution. © The Author(s) 2015.

  13. The Tancitaro Debris Avalanche: Characterization, propagation and modeling

    Science.gov (United States)

    Morelli, Stefano; Monroy, Victor Hugo Garduño; Gigli, Giovanni; Falorni, Giacomo; Rocha, Eleazar Arreygue; Casagli, Nicola

    2010-06-01

    observations suggest that these are mainly related to weakening processes operating both in volcanoes and in non-volcanic areas. The runout of the Tancitaro debris avalanche was numerically modeled using DAN-W. The geotechnical parameters determined in the field and from the laboratory analyses were used as input. The DAN-W code models longitudinal spreading and the thickness and velocity of the failed mass by opportunely selecting a specific rheological model (Voellmy, Frictional, Bingham). Thus, it was determined that the two-parameter "Voellmy model" provided the best simulation of the Tancitaro debris avalanche movement, and the best fitting rheological parameters have been found through back analysis.

  14. An enhanced temperature index model for debris-covered glaciers accounting for thickness effect

    Science.gov (United States)

    Carenzo, M.; Pellicciotti, F.; Mabillard, J.; Reid, T.; Brock, B. W.

    2016-08-01

    Debris-covered glaciers are increasingly studied because it is assumed that debris cover extent and thickness could increase in a warming climate, with more regular rockfalls from the surrounding slopes and more englacial melt-out material. Debris energy-balance models have been developed to account for the melt rate enhancement/reduction due to a thin/thick debris layer, respectively. However, such models require a large amount of input data that are not often available, especially in remote mountain areas such as the Himalaya, and can be difficult to extrapolate. Due to their lower data requirements, empirical models have been used extensively in clean glacier melt modelling. For debris-covered glaciers, however, they generally simplify the debris effect by using a single melt-reduction factor which does not account for the influence of varying debris thickness on melt and prescribe a constant reduction for the entire melt across a glacier. In this paper, we present a new temperature-index model that accounts for debris thickness in the computation of melt rates at the debris-ice interface. The model empirical parameters are optimized at the point scale for varying debris thicknesses against melt rates simulated by a physically-based debris energy balance model. The latter is validated against ablation stake readings and surface temperature measurements. Each parameter is then related to a plausible set of debris thickness values to provide a general and transferable parameterization. We develop the model on Miage Glacier, Italy, and then test its transferability on Haut Glacier d'Arolla, Switzerland. The performance of the new debris temperature-index (DETI) model in simulating the glacier melt rate at the point scale is comparable to the one of the physically based approach, and the definition of model parameters as a function of debris thickness allows the simulation of the nonlinear relationship of melt rate to debris thickness, summarised by the

  15. Differentiating littering, urban runoff and marine transport as sources of marine debris in coastal and estuarine environments

    Science.gov (United States)

    Willis, Kathryn; Denise Hardesty, Britta; Kriwoken, Lorne; Wilcox, Chris

    2017-03-01

    Marine debris is a burgeoning global issue with economic, ecological and aesthetic impacts. While there are many studies now addressing this topic, the influence of urbanisation factors such as local population density, stormwater drains and roads on the distribution of coastal litter remains poorly understood. To address this knowledge gap, we carried out standardized surveys at 224 transect surveys at 67 sites in two estuaries and along the open coast in Tasmania, Australia. We explored the relative support for three hypotheses regarding the sources of the debris; direct deposition by beachgoers, transport from surrounding areas via storm water drains and coastal runoff, and onshore transport from the marine system. We found strong support for all three mechanisms, however, onshore transport from the marine reservoir was the most important mechanism. Overall, the three models together explained 45.8 percent of the variation in our observations. Our results also suggest that most debris released into the marine environment is deposited locally, which may be the answer to where all the missing plastic is in the ocean. Furthermore, local interventions are likely to be most effective in reducing land-based inputs into the ocean.

  16. Differentiating littering, urban runoff and marine transport as sources of marine debris in coastal and estuarine environments.

    Science.gov (United States)

    Willis, Kathryn; Denise Hardesty, Britta; Kriwoken, Lorne; Wilcox, Chris

    2017-03-10

    Marine debris is a burgeoning global issue with economic, ecological and aesthetic impacts. While there are many studies now addressing this topic, the influence of urbanisation factors such as local population density, stormwater drains and roads on the distribution of coastal litter remains poorly understood. To address this knowledge gap, we carried out standardized surveys at 224 transect surveys at 67 sites in two estuaries and along the open coast in Tasmania, Australia. We explored the relative support for three hypotheses regarding the sources of the debris; direct deposition by beachgoers, transport from surrounding areas via storm water drains and coastal runoff, and onshore transport from the marine system. We found strong support for all three mechanisms, however, onshore transport from the marine reservoir was the most important mechanism. Overall, the three models together explained 45.8 percent of the variation in our observations. Our results also suggest that most debris released into the marine environment is deposited locally, which may be the answer to where all the missing plastic is in the ocean. Furthermore, local interventions are likely to be most effective in reducing land-based inputs into the ocean.

  17. An Estimation of Construction and Demolition Debris in Seoul, Korea: Waste Amount, Type, and Estimating Model.

    Science.gov (United States)

    Seo, Seongwon; Hwang, Yongwoo

    1999-08-01

    Construction and demolition (C&D) debris is generated at the site of various construction activities. However, the amount of the debris is usually so large that it is necessary to estimate the amount of C&D debris as accurately as possible for effective waste management and control in urban areas. In this paper, an effective estimation method using a statistical model was proposed. The estimation process was composed of five steps: estimation of the life span of buildings; estimation of the floor area of buildings to be constructed and demolished; calculation of individual intensity units of C&D debris; and estimation of the future C&D debris production. This method was also applied in the city of Seoul as an actual case, and the estimated amount of C&D debris in Seoul in 2021 was approximately 24 million tons. Of this total amount, 98% was generated by demolition, and the main components of debris were concrete and brick.

  18. The international environment UNISPACE '82 and the ITU: A relationship between orbit-spectrum resource allocation and orbital debris

    Science.gov (United States)

    Olmstead, D.

    1985-01-01

    The 1985 Space WARC will examine and potentially modify the current geostationary orbit spectrum resource allocation methodology. Discussions in this international political environment could likely associate the geostationary orbital debris issue with the politicized issue of orbit spectrum allocation.

  19. Modelling the fate of marine debris along a complex shoreline: Lessons from the Great Barrier Reef

    Science.gov (United States)

    Critchell, K.; Grech, A.; Schlaefer, J.; Andutta, F. P.; Lambrechts, J.; Wolanski, E.; Hamann, M.

    2015-12-01

    The accumulation of floating anthropogenic debris in marine and coastal areas has environmental, economic, aesthetic, and human health impacts. Until now, modelling the transport of such debris has largely been restricted to the large-scales of open seas. We used oceanographic modelling to identify potential sites of debris accumulation along a rugged coastline with headlands, islands, rocky coasts and beaches. Our study site was the Great Barrier Reef World Heritage Area that has an emerging problem with debris accumulation. We found that the classical techniques of modelling the transport of floating debris models are only moderately successful due to a number of unknowns or assumptions, such as the value of the wind drift coefficient, the variability of the oceanic forcing and of the wind, the resuspension of some floating debris by waves, and the poorly known relative contribution of floating debris from urban rivers and commercial and recreational shipping. Nevertheless the model was successful in reproducing a number of observations such as the existence of hot spots of accumulation. The orientation of beaches to the prevailing wind direction affected the accumulation rate of debris. The wind drift coefficient and the exact timing of the release of the debris at sea affected little the movement of debris originating from rivers but it affected measurably that of debris originating from ships. It was thus possible to produce local hotspot maps for floating debris, especially those originating from rivers. Such modelling can be used to inform local management decisions, and it also identifies likely priority research areas to more reliably predict the trajectory and landing points of floating debris.

  20. CFD modelling of insulation debris transport phenomena in water flow

    Energy Technology Data Exchange (ETDEWEB)

    Krepper, Eeckhard; Cartland-Glover, Gregory; Grahn, Alexander [Forschungszentrum Rossendorf e.V., Dresden (Germany). Inst. fuer Sicherheitsforschung

    2009-11-15

    The investigation of insulation debris generation, transport and sedimentation becomes important with regard to reactor safety research for PWR and BWR, when considering the long-term behaviour of emergency core cooling systems during all types of loss of coolant accidents. A joint research project on such questions is being performed in cooperation between the University of Applied Sciences Zittau/Goerlitz and the Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation of particle transport phenomena in coolant flow and the development of CFD models for its description. While the experiments are performed at the University at Zittau/Goerlitz, the theoretical modelling efforts are concentrated at Forschungszentrum Dresden-Rossendorf. In the current paper the basic concepts for CFD modelling are described and feasibility studies are presented. (orig.)

  1. Modeling the transport and accumulation floating debris generated by the 11 March 2011 Tohoku tsunami.

    Science.gov (United States)

    Lebreton, Laurent C-M; Borrero, Jose C

    2013-01-15

    A global ocean circulation model is coupled to a particle-tracking model to simulate the transport of floating debris washed into the North Pacific Ocean by the Tohoku tsunami. A release scenario for the tsunami debris is based on coastal population and measured tsunami runup. Archived 2011/2012 hindcast current data is used to model the transport of debris since the tsunami, while data from 2008 to 2012 is used to investigate the distribution of debris on timescales up to 4years. The vast amount of debris pushed into ocean likely represents thousands of years worth of 'normal' litter flux from Japan's urbanized coastline. This is important since a significant fraction of the debris will be comprised of plastics, some of which will degrade into tiny particles and be consumed by marine organisms, thereby allowing adsorbed organic pollutants to enter our food supply in quantities much higher than present. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Models and correlations of the DEBRIS Late-Phase Melt Progression Model

    International Nuclear Information System (INIS)

    Schmidt, R.C.; Gasser, R.D.

    1997-09-01

    The DEBRIS Late Phase Melt Progression Model is an assembly of models, embodied in a computer code, which is designed to treat late-phase melt progression in dry rubble (or debris) regions that can form as a consequence of a severe core uncover accident in a commercial light water nuclear reactor. The approach is fully two-dimensional, and incorporates a porous medium modeling framework together with conservation and constitutive relationships to simulate the time-dependent evolution of such regions as various physical processes act upon the materials. The objective of the code is to accurately model these processes so that the late-phase melt progression that would occur in different hypothetical severe nuclear reactor accidents can be better understood and characterized. In this report the models and correlations incorporated and used within the current version of DEBRIS are described. These include the global conservation equations solved, heat transfer and fission heating models, melting and refreezing models (including material interactions), liquid and solid relocation models, gas flow and pressure field models, and the temperature and compositionally dependent material properties employed. The specific models described here have been used in the experiment design analysis of the Phebus FPT-4 debris-bed fission-product release experiment. An earlier DEBRIS code version was used to analyze the MP-1 and MP-2 late-phase melt progression experiments conducted at Sandia National Laboratories for the US Nuclear Regulatory Commission

  3. Models and correlations of the DEBRIS Late-Phase Melt Progression Model

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, R.C.; Gasser, R.D. [Sandia National Labs., Albuquerque, NM (United States). Reactor Safety Experiments Dept.

    1997-09-01

    The DEBRIS Late Phase Melt Progression Model is an assembly of models, embodied in a computer code, which is designed to treat late-phase melt progression in dry rubble (or debris) regions that can form as a consequence of a severe core uncover accident in a commercial light water nuclear reactor. The approach is fully two-dimensional, and incorporates a porous medium modeling framework together with conservation and constitutive relationships to simulate the time-dependent evolution of such regions as various physical processes act upon the materials. The objective of the code is to accurately model these processes so that the late-phase melt progression that would occur in different hypothetical severe nuclear reactor accidents can be better understood and characterized. In this report the models and correlations incorporated and used within the current version of DEBRIS are described. These include the global conservation equations solved, heat transfer and fission heating models, melting and refreezing models (including material interactions), liquid and solid relocation models, gas flow and pressure field models, and the temperature and compositionally dependent material properties employed. The specific models described here have been used in the experiment design analysis of the Phebus FPT-4 debris-bed fission-product release experiment. An earlier DEBRIS code version was used to analyze the MP-1 and MP-2 late-phase melt progression experiments conducted at Sandia National Laboratories for the US Nuclear Regulatory Commission.

  4. Creating a GIS-based model of marine debris "hot spots" to improve efficiency of a lobster trap debris removal program.

    Science.gov (United States)

    Martens, Justin; Huntington, Brittany E

    2012-05-01

    Debris removal programs are combatting the accumulation of derelict fishing gear and other debris in marine habitats. We analyzed 5 years of lobster trap debris removal data in Biscayne National Park, Florida to assess removal efficiency and develop spatially-explicit mapping tools to guide future removals. We generated and validated debris "hot spots" maps that combined remotely-sensed data (i.e. benthic habitat type and bathymetry) with 862 locations of previous debris collection. Our hot spot models spatially depict regions of likely debris accumulation, reducing the search area by 95% (from 332 km(2) to 18 km(2)) and encompassing 100% of the validation sites. Our analyses indicate removal contractors using sub-surface towed divers enhanced debris recovery. Additionally, the quantity of debris removed did not decrease with increased efforts, suggesting that debris supply in situ exceeds removal efforts. We conclude with the importance of coupling analysis of ongoing debris removal programs with GIS technology to improve removal efforts. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. The Impact of New Trends in Satellite Launches on the Orbital Debris Environment

    Science.gov (United States)

    Karacalioglu, Arif Goektug; Stupl, Jan

    2016-01-01

    The main goal of this study is to examine the impact of new trends in satellite launch activities on the orbital debris environment and collision risk. As a foundation for the study, we developed a deployment scenario for satellites and associated rocket bodies based on publicly announced future missions. The upcoming orbital injection technologies, such as the new launch vehicles dedicated for small spacecraft and propulsive interstages, are also considered in this scenario. We then used a simulation tool developed in-house to propagate the objects within this scenario using variable-sized time-steps as small as one second to detect conjunctions between objects. The simulation makes it possible to follow the short- and long-term effects of a particular satellite or constellation in the space environment. Likewise, the effects of changes in the debris environment on a particular satellite or constellation can be evaluated. It is our hope that the results of this paper and further utilization of the developed simulation tool will assist in the investigation of more accurate deorbiting metrics to replace the generic 25-year disposal guidelines, as well as to guide future launches toward more sustainable and safe orbits.

  6. A 2D-3D strategy for resolving tsunami-generated debris flow in urban environments

    Science.gov (United States)

    Birjukovs Canelas, Ricardo; Conde, Daniel; Garcia-Feal, Orlando; João Telhado, Maria; Ferreira, Rui M. L.

    2017-04-01

    The incorporation of solids, either sediment from the natural environment or remains from buildings or infrastructures is a relevant feature of tsunami run-up in urban environments, greatly increasing the destructive potential of tsunami propagation. Two-dimensional (2D) models have been used to assess the propagation of the bore, even in dense urban fronts. Computational advances are introduced in this work, namely a fully lagrangian, 3D description of the fluid-solid flow, coupled with a high performance meshless implementation capable of dealing with large domains and fine discretizations. A Smoothed Particle Hydrodynamics (SPH) Navier-Stokes discretization and a Distributed Contact Discrete Element Method (DCDEM) description of solid-solid interactions provide a state-of the-art fluid-solid flow description. Together with support for arbitrary geometries, centimetre scale resolution simulations of a city section in Lisbon downtown are presented. 2D results are used as boundary conditions for the 3D model, characterizing the incoming wave as it approaches the coast. It is shown that the incoming bore is able to mobilize and incorporate standing vehicles and other urban hardware. Such fully featured simulation provides explicit description of the interactions among fluid, floating debris (vehicles and urban furniture), the buildings and the pavement. The proposed model presents both an innovative research tool for the study of these flows and a powerful and robust approach to study, design and test mitigation solutions at the local scale. At the same time, due to the high time and space resolution of these methodologies, new questions are raised: scenario-building and initial configurations play a crucial role but they do not univocally determine the final configuration of the simulation, as the solution of the Navier-Stokes equations for high Reynolds numbers possesses a high number of degrees of freedom. This calls for conducting the simulations in a

  7. Microbial hitchhikers on marine plastic debris: Human exposure risks at bathing waters and beach environments.

    Science.gov (United States)

    Keswani, Anisha; Oliver, David M; Gutierrez, Tony; Quilliam, Richard S

    2016-07-01

    Marine plastic debris is well characterized in terms of its ability to negatively impact terrestrial and marine environments, endanger coastal wildlife, and interfere with navigation, tourism and commercial fisheries. However, the impacts of potentially harmful microorganisms and pathogens colonising plastic litter are not well understood. The hard surface of plastics provides an ideal environment for opportunistic microbial colonisers to form biofilms and might offer a protective niche capable of supporting a diversity of different microorganisms, known as the "Plastisphere". This biotope could act as an important vector for the persistence and spread of pathogens, faecal indicator organisms (FIOs) and harmful algal bloom species (HABs) across beach and bathing environments. This review will focus on the existent knowledge and research gaps, and identify the possible consequences of plastic-associated microbes on human health, the spread of infectious diseases and bathing water quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Effects of ground freezing and snow avalanche deposits on debris flows in alpine environments

    Directory of Open Access Journals (Sweden)

    E. Bardou

    2004-01-01

    Full Text Available Debris flows consist of a mixture of water and sediments of various sizes. Apart from few exceptions, the water is usually contributed directly from precipitation. In a high mountain environment like the Alps, it appears necessary to consider infiltration of water into the ground during rainfall events, the runoff characteristics and the potential supply of sediment as a function of a multitude of climatic and hydrogeological factors. This paper outlines several new processes - either linked to ice formation in the ground before an event, or to the presence of snow avalanche deposits - that change the probability of observing an event. These processes were identified during field observations connected with extreme weather events that occurred recently in the Valais Alps (south-western Switzerland: they can be seen as factors either amplifying or reducing the potential of slope instability caused by the precipitation event. An intense freezing of the ground during the week preceding the exceptional rainfall event in mid-October 2000 amplified the probability of triggering debris flows between roughly 1800 and 2300m asl. Both growth of ice needles and superficial ground freezing destroyed soil aggregates (increasing the availability of sediments and/or, a deeper ground freezing resulted in decreased infiltration rate (increased runoff during the first hours of heavy rainfall. The presence of snow avalanche deposits in a gully could be simultaneously an amplifying factor (the snow deposits increase the base flow and create a sliding plane for the sediments, mainly at the time of summer storms or a reducing factor (reduction in the impact energy of the raindrops, mainly at the time of winter storms of the risk of triggering debris flows. If it is not currently possible to establish rainfall threshold values for debris flow triggering, the knowledge and the implementation of these processes in the analysis of the potential triggering (for example by

  9. Potential transfer of organic pollutants from littoral plastics debris to the marine environment.

    Science.gov (United States)

    León, Víctor M; García, Inés; González, Emilia; Samper, Raquel; Fernández-González, Verónica; Muniategui-Lorenzo, Soledad

    2018-02-05

    Plastic polymers act as passive samplers in air system and concentrate hydrophobic organic contaminants by sorption or specific interactions, which can be transported to other systems such as the marine environment. In this study plastic debris was sampled in the surrounding area of a Mediterranean lagoon in order to determine the concentration of persistent and emerging organic contaminants. More specifically, desorption of 91 regulated and emerging organic contaminants (polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorinated pesticides, current-use pesticides, personal care products, other pesticides and plastic additives) was characterized for the first 24 h from different polymers to seawater and the remaining content of these contaminants was also extracted by ultrasonic extraction with methanol. All samples were analyzed by Stir Bar Sorptive Extraction coupled to GC/MS. A significant fraction of sorbed contaminants in polymers was desorbed in the first 24 h, particularly for triazines and organophosphorus pesticides due to their lower hydrophobicity than other considered analytes. The remaining contaminants contained in plastics can be also transferred to seawater, sediments or biota. Considering 24 h desorbed fraction plus the remaining methanol extracted fraction, the highest transfer levels corresponded to personal care products, plastic additives, current-use pesticides and PAHs. This is the first study to show the relevance of the transport of organic contaminants on plastic debris from littoral areas to the marine environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Modelling ice-cliff backwasting on a debris-covered glacier in the Nepalese Himalaya

    NARCIS (Netherlands)

    Steiner, Jakob F.; Pellicciotti, Francesca; Buri, Pascal; Miles, Evan S.; Immerzeel, Walter W.|info:eu-repo/dai/nl/290472113; Reid, Tim D.

    2015-01-01

    Ice cliffs have been identified as a reason for higher ablation rates on debris-covered glaciers than are implied by the insulation effects of the debris. This study aims to improve our understanding of cliff backwasting, and the role of radiative fluxes in particular. An energy-balance model is

  11. NASA Orbital Debris Engineering Model ORDEM2008 (Beta Version)

    Science.gov (United States)

    Stansbery, Eugene G.; Krisko, Paula H.

    2009-01-01

    This is an interim document intended to accompany the beta-release of the ORDEM2008 model. As such it provides the user with a guide for its use, a list of its capabilities, a brief summary of model development, and appendices included to educate the user as to typical runtimes for different orbit configurations. More detailed documentation will be delivered with the final product. ORDEM2008 supersedes NASA's previous model - ORDEM2000. The availability of new sensor and in situ data, the re-analysis of older data, and the development of new analytical techniques, has enabled the construction of this more comprehensive and sophisticated model. Integrated with the software is an upgraded graphical user interface (GUI), which uses project-oriented organization and provides the user with graphical representations of numerous output data products. These range from the conventional average debris size vs. flux magnitude for chosen analysis orbits, to the more complex color-contoured two-dimensional (2-D) directional flux diagrams in terms of local spacecraft pitch and yaw.

  12. Seaweeds and plastic debris can influence the survival of faecal indicator organisms in beach environments.

    Science.gov (United States)

    Quilliam, Richard S; Jamieson, Julie; Oliver, David M

    2014-07-15

    The revised Bathing Water Directive (rBWD) introduces more stringent standards for microbial water quality and promotes more pro-active management of the beach environment through the production of a bathing water profile (BWP). The aim of this study was to determine whether living seaweeds in the littoral zone are colonised by faecal indicator organisms (FIOs), and to quantify the survival dynamics of waterborne Escherichia coli in microcosms containing senescing seaweeds. Living seaweed (Fucus spiralis) was not associated with FIO colonisation, although could be providing a protected environment in the underlying sand. Senescing seaweeds enhanced waterborne E. coli survival compared to plastic debris, with the brown seaweed Laminaria saccharina facilitating greater E. coli persistence than either Chondrus crispus or Ulva lactuca. This has important implications for FIO survival on bathing beaches as the majority of beach-cast biomass is composed of brown seaweeds, which could support significant levels of FIOs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Calibration of numerical models for small debris flows in Yosemite Valley, California, USA

    Directory of Open Access Journals (Sweden)

    P. Bertolo

    2005-01-01

    Full Text Available This study compares documented debris flow runout distances with numerical simulations in the Yosemite Valley of California, USA, where about 15% of historical events of slope instability can be classified as debris flows and debris slides (Wieczorek and Snyder, 2004. To model debris flows in the Yosemite Valley, we selected six streams with evidence of historical debris flows; three of the debris flow deposits have single channels, and the other three split their pattern in the fan area into two or more channels. From field observations all of the debris flows involved coarse material, with only very small clay content. We applied the one dimensional DAN (Dynamic ANalysis model (Hungr, 1995 and the two-dimensional FLO-2D model (O'Brien et al., 1993 to predict and compare the runout distance and the velocity of the debris flows observed in the study area. As a first step, we calibrated the parameters for the two softwares through the back analysis of three debris- flows channels using a trial-and-error procedure starting with values suggested in the literature. In the second step we applied the selected values to the other channels, in order to evaluate their predictive capabilities. After parameter calibration using three debris flows we obtained results similar to field observations We also obtained a good agreement between the two models for velocities. Both models are strongly influenced by topography: we used the 30 m cell size DTM available for the study area, that is probably not accurate enough for a highly detailed analysis, but it can be sufficient for a first screening.

  14. Debris flow hazard modelling on medium scale: Valtellina di Tirano, Italy

    Directory of Open Access Journals (Sweden)

    J. Blahut

    2010-11-01

    Full Text Available Debris flow hazard modelling at medium (regional scale has been subject of various studies in recent years. In this study, hazard zonation was carried out, incorporating information about debris flow initiation probability (spatial and temporal, and the delimitation of the potential runout areas. Debris flow hazard zonation was carried out in the area of the Consortium of Mountain Municipalities of Valtellina di Tirano (Central Alps, Italy. The complexity of the phenomenon, the scale of the study, the variability of local conditioning factors, and the lacking data limited the use of process-based models for the runout zone delimitation. Firstly, a map of hazard initiation probabilities was prepared for the study area, based on the available susceptibility zoning information, and the analysis of two sets of aerial photographs for the temporal probability estimation. Afterwards, the hazard initiation map was used as one of the inputs for an empirical GIS-based model (Flow-R, developed at the University of Lausanne (Switzerland. An estimation of the debris flow magnitude was neglected as the main aim of the analysis was to prepare a debris flow hazard map at medium scale. A digital elevation model, with a 10 m resolution, was used together with landuse, geology and debris flow hazard initiation maps as inputs of the Flow-R model to restrict potential areas within each hazard initiation probability class to locations where debris flows are most likely to initiate. Afterwards, runout areas were calculated using multiple flow direction and energy based algorithms. Maximum probable runout zones were calibrated using documented past events and aerial photographs. Finally, two debris flow hazard maps were prepared. The first simply delimits five hazard zones, while the second incorporates the information about debris flow spreading direction probabilities, showing areas more likely to be affected by future debris flows. Limitations of the modelling arise

  15. JSC Orbital Debris Website Description

    Science.gov (United States)

    Johnson, Nicholas L.

    2006-01-01

    Purpose: The website provides information about the NASA Orbital Debris Program Office at JSC, which is the lead NASA center for orbital debris research. It is recognized world-wide for its leadership in addressing orbital debris issues. The NASA Orbital Debris Program Office has taken the international lead in conducting measurements of the environment and in developing the technical consensus for adopting mitigation measures to protect users of the orbital environment. Work at the center continues with developing an improved understanding of the orbital debris environment and measures that can be taken to control its growth. Major Contents: Orbital Debris research is divided into the following five broad efforts. Each area of research contains specific information as follows: 1) Modeling - NASA scientists continue to develop and upgrade orbital debris models to describe and characterize the current and future debris environment. Evolutionary and engineering models are described in detail. Downloadable items include a document in PDF format and executable software. 2) Measurements - Measurements of near-Earth orbital debris are accomplished by conducting ground-based and space-based observations of the orbital debris environment. The data from these sources provide validation of the environment models and identify the presence of new sources. Radar, optical and surface examinations are described. External links to related topics are provided. 3) Protection - Orbital debris protection involves conducting hypervelocity impact measurements to assess the risk presented by orbital debris to operating spacecraft and developing new materials and new designs to provide better protection from the environment with less weight penalty. The data from this work provides the link between the environment defined by the models and the risk presented by that environment to operating spacecraft and provides recommendations on design and operations procedures to reduce the risk as

  16. Colisional Cloud Debris and Propelled Evasive Maneuvers

    Science.gov (United States)

    Ferreira, L. S.; Jesus, A. D. C.; Carvalho, T. C. F.; Sousa, R. R.

    2017-10-01

    Space debris clouds exist at various altitudes in the environment outside the Earth. Fragmentation of debris and/or collision between the debris of a cloud increases the amount of debris, producing smaller debris. This event also increases significantly the chances of collision with operational vehicles in orbit. In this work we study clouds of debris that are close to a spacecraft in relation to its distance from the center of the Earth. The results show several layers of colliding debris depending on their size over time of evasive maneuvers of the vehicle. In addition, we have tested such maneuvers for propulsion systems with a linear and exponential mass variation model. The results show that the linear propulsion system is more efficient.

  17. SCDAP/RELAP5 modeling of heat transfer and flow losses in lower head porous debris. Rev. 1

    International Nuclear Information System (INIS)

    Siefken, L.J.; Coryell, E.W.; Paik, S.; Kuo, H.

    1999-01-01

    Designs are described for implementing models for calculating the heat transfer and flow losses in porous debris in the lower head of a reactor vessel. The COUPLE model in SCDAP/RELAP5 represents both the porous and nonporous debris that results from core material slumping into the lower head. Currently, the COUPLE model has the capability to model convective and radiative heat transfer from the surfaces of nonporous debris in a detailed manner and to model only in a simplistic manner the heat transfer from porous debris. In order to advance beyond the simplistic modeling for porous debris, designs are developed for detailed calculations of heat transfer and flow losses in porous debris. Correlations are identified for convective heat transfer in porous debris for the following modes of heat transfer; (1) forced convection to liquid, (2) forced convection to gas, (3) nucleate boiling, (4) transition boiling, and (5) film boiling. Interphase heat transfer is modeled in an approximate ma nner. Designs are described for models to calculate the flow losses and interphase drag of fluid flowing through the interstices of the porous debris, and to apply these variables in the momentum equations in the RELAP5 part of the code. Since the models for heat transfer and flow losses in porous debris in the lower head are designed for general application, a design is also described for implementation of these models to the analysis of porous debris in the core region. A test matrix is proposed for assessing the capability of the implemented models to calculate the heat transfer and flow losses in porous debris. The implementation of the models described in this report is expected to improve the COUPLE code calculation of the temperature distribution in porous debris and in the lower head that supports the debris. The implementation of these models is also expected to improve the calculation of the temperature and flow distribution in porous debris in the core region

  18. Space Shuttle Solid Rocket Booster Debris Assessment

    Science.gov (United States)

    Kendall, Kristin; Kanner, Howard; Yu, Weiping

    2006-01-01

    The Space Shuttle Columbia Accident revealed a fundamental problem of the Space Shuttle Program regarding debris. Prior to the tragedy, the Space Shuttle requirement stated that no debris should be liberated that would jeopardize the flight crew and/or mission success. When the accident investigation determined that a large piece of foam debris was the primary cause of the loss of the shuttle and crew, it became apparent that the risk and scope of - damage that could be caused by certain types of debris, especially - ice and foam, were not fully understood. There was no clear understanding of the materials that could become debris, the path the debris might take during flight, the structures the debris might impact or the damage the impact might cause. In addition to supporting the primary NASA and USA goal of returning the Space Shuttle to flight by understanding the SRB debris environment and capability to withstand that environment, the SRB debris assessment project was divided into four primary tasks that were required to be completed to support the RTF goal. These tasks were (1) debris environment definition, (2) impact testing, (3) model correlation and (4) hardware evaluation. Additionally, the project aligned with USA's corporate goals of safety, customer satisfaction, professional development and fiscal accountability.

  19. Cost and risk assessment for spacecraft operation decisions caused by the space debris environment

    Science.gov (United States)

    Schaub, Hanspeter; Jasper, Lee E. Z.; Anderson, Paul V.; McKnight, Darren S.

    2015-08-01

    Space debris is a topic of concern among many in the space community. Most forecasting analyses look centuries into the future to attempt to predict how severe debris densities and fluxes will become in orbit regimes of interest. Conversely, space operators currently do not treat space debris as a major mission hazard. This survey paper outlines the range of cost and risk evaluations a space operator must consider when determining a debris-related response. Beyond the typical direct costs of performing an avoidance maneuver, the total cost including indirect costs, political costs and space environmental costs are discussed. The weights on these costs can vary drastically across mission types and orbit regimes flown. The operator response options during a mission are grouped into four categories: no action, perform debris dodging, follow stricter mitigation, and employ ADR. Current space operations are only considering the no action and debris dodging options, but increasing debris risk will eventually force the stricter mitigation and ADR options. Debris response equilibria where debris-related risks and costs settle on a steady-state solution are hypothesized.

  20. On the evaluation of debris flows dynamics by means of mathematical models

    Directory of Open Access Journals (Sweden)

    M. Arattano

    2003-01-01

    Full Text Available The prediction of debris flow dynamic characteristics in a debris flow prone torrent is generally made through the investigation of past events. This investigation can be carried out through a survey of the marks left by past debris flows along the channel and through a detailed analysis of the type and shape of the deposits found on the debris fan. The rheological behaviour of future debris flows can then be inferred from the results of these surveys and their dynamic characteristics can be estimated applying well known formulas proposed in literature. These latter will make use of the assumptions on the rheological behaviour previously made. This type of estimation has been performed for a debris flow occurred in an instrumented basin, on the North-Eastern Italian Alps, in 1996 and the results have been compared to those obtained by means of a mathematical simulation. For the calibration of the mathematical model the limnographs recorded by three different ultrasonic gauges installed along a torrent reach on the fan were used. The comparison evidenced the importance of time data recordings for a correct prediction of the debris flows dynamics. Without the availability of data recordings, the application of formulas based only on assumptions derived from field analysis could be misleading.

  1. Model simulations of flood and debris flow timing in steep catchments after wildfire

    Science.gov (United States)

    Rengers, Francis; McGuire, Luke; Kean, Jason W.; Staley, Dennis M.; Hobley, D.E.J

    2016-01-01

    Debris flows are a typical hazard on steep slopes after wildfire, but unlike debris flows that mobilize from landslides, most post-wildfire debris flows are generated from water runoff. The majority of existing debris-flow modeling has focused on landslide-triggered debris flows. In this study we explore the potential for using process-based rainfall-runoff models to simulate the timing of water flow and runoff-generated debris flows in recently burned areas. Two different spatially distributed hydrologic models with differing levels of complexity were used: the full shallow water equations and the kinematic wave approximation. Model parameter values were calibrated in two different watersheds, spanning two orders of magnitude in drainage area. These watersheds were affected by the 2009 Station Fire in the San Gabriel Mountains, CA, USA. Input data for the numerical models were constrained by time series of soil moisture, flow stage, and rainfall collected at field sites, as well as high-resolution lidar-derived digital elevation models. The calibrated parameters were used to model a third watershed in the burn area, and the results show a good match with observed timing of flow peaks. The calibrated roughness parameter (Manning's $n$) was generally higher when using the kinematic wave approximation relative to the shallow water equations, and decreased with increasing spatial scale. The calibrated effective watershed hydraulic conductivity was low for both models, even for storms occurring several months after the fire, suggesting that wildfire-induced changes to soil-water infiltration were retained throughout that time. Overall the two model simulations were quite similar suggesting that a kinematic wave model, which is simpler and more computationally efficient, is a suitable approach for predicting flood and debris flow timing in steep, burned watersheds.

  2. Integration of two-phase solid fluid equations in a catchment model for flashfloods, debris flows and shallow slope failures

    KAUST Repository

    Bout, B.

    2018-04-09

    An integrated, modeling method for shallow landslides, debris flows and catchment hydrology is developed and presented in this paper. Existing two-phase debris flow equations and an adaptation on the infinite slope method are coupled with a full hydrological catchment model. We test the approach on the 4 km2 Scaletta catchment, North-Eastern Sicily, where the 1-10-2009 convective storm caused debris flooding after 395 shallow landslides. Validation is done based on the landslide inventory and photographic evidence from the days after the event. Results show that the model can recreate the impact of both shallow landslides, debris flow runout, and debris floods with acceptable accuracy (91 percent inventory overlap with a 0.22 Cohens Kappa). General patterns in slope failure and runout are well-predicted, leading to a fully physically based prediction of rainfall induced debris flood behavior in the downstream areas, such as the creation of a debris fan at the coastal outlet.

  3. Design report on SCDAP/RELAP5 model improvements - debris bed and molten pool behavior

    International Nuclear Information System (INIS)

    Allison, C.M.; Rempe, J.L.; Chavez, S.A.

    1994-11-01

    The SCDAP/RELAP5/MOD3 computer code is designed to describe the overall reactor coolant system thermal-hydraulic response, core damage progression, and in combination with VICTORIA, fission product release and transport during severe accidents. Improvements for existing debris bed and molten pool models in the SCDAP/RELAP5/MOD3.1 code are described in this report. Model improvements to address (a) debris bed formation, heating, and melting; (b) molten pool formation and growth; and (c) molten pool crust failure are discussed. Relevant data, existing models, proposed modeling changes, and the anticipated impact of the changes are discussed. Recommendations for the assessment of improved models are provided

  4. NASA Orbital Debris Baseline Populations

    Science.gov (United States)

    Krisko, Paula H.; Vavrin, A. B.

    2013-01-01

    The NASA Orbital Debris Program Office has created high fidelity populations of the debris environment. The populations include objects of 1 cm and larger in Low Earth Orbit through Geosynchronous Transfer Orbit. They were designed for the purpose of assisting debris researchers and sensor developers in planning and testing. This environment is derived directly from the newest ORDEM model populations which include a background derived from LEGEND, as well as specific events such as the Chinese ASAT test, the Iridium 33/Cosmos 2251 accidental collision, the RORSAT sodium-potassium droplet releases, and other miscellaneous events. It is the most realistic ODPO debris population to date. In this paper we present the populations in chart form. We describe derivations of the background population and the specific populations added on. We validate our 1 cm and larger Low Earth Orbit population against SSN, Haystack, and HAX radar measurements.

  5. r.avaflow, the GIS simulation model for avalanche and debris flows: new developments and challenges

    Science.gov (United States)

    Mergili, Martin; Queiroz de Oliveira, Gustavo; Fischer, Jan-Thomas; Krenn, Julia; Kulisch, Helmut; Malcherek, Andreas; Pudasaini, Shiva P.

    2016-04-01

    We present the latest developments and discuss some of the key challenges with regard to the novel and unified computational tool r.avaflow, representing an advanced, comprehensive, GIS-based open source simulation environment for two-phase geophysical mass flows such as avalanches of snow or rock, flows of debris or mud, and related process chains. r.avaflow is freely available and adoptable as a raster module of the GRASS GIS software (http://www.avaflow.org). We focus on the following issues: (1) We back-calculate a laboratory-scale debris flow experiment with r.avaflow and thereby show that different types of drag may govern the evolving flow dynamics, depending on the initial flow configuratiuon. In particular, it appears necessary to consider viscous ambient drag in order to achieve simulation results in line with experimentally measurements. (2) We employ a set of well-documented rock avalanche events to illustrate the use of a built-in functionality for parameter sensitivity analysis and optimization. To do so, we demonstrate possible strategies going beyond the deficient one-at-a-time simulation approach. They allow us to test three or more parameters at once with a limited number of model runs. Computational times are kept at an acceptable level by multi-core processing strategies and use of the Vienna Scientific Cluster. We further discuss a number of key issues with regard to (i) arbitrary mountain topography; and (ii) entrainment and deposition of material. Most tests indicate a good model performance when the affected areas predicted for a late stage of the flow simulation are compared with observed affected areas. However, we note that such a validation is not fully justified without the implementation of a physically correct model for the deposition process. Acknowledgement: The work was conducted as part of the international cooperation project "A GIS simulation model for avalanche and debris flows (avaflow)" supported by the Austrian Science Fund

  6. Numerical Modeling of Debris Flow Force Caused by Climate Change and Its application to Check Dam

    Science.gov (United States)

    KIM, S. D.; Jun, K.; JUN, B. H.; Lee, H. J.; TAK, W. J.

    2016-12-01

    Due to global warming, climate change cause a super hurricane and heavy rainfall frequently. Heavy rainfall cause by debris flow in mountainous terrains, and disasters by debris flow force have continuously increased. The purpose of this study is to analyze the characteristics of debris flow force acting on the check dam. The numerical approach to the debris flow force was performed by the Finite Difference Method (FDM) based on the erosion-deposition combination model including the equation of continuity, mass conservation, and momentum conservation. In order to investigate behavior of the debris flow force according to the variance of supplying water discharge and channel slope angle, a rectangular straight channel and one closed type check dam was set up for conducting numerical simulations. As the supply water discharges increase, the curve of the impact force by debris flow becomes unstable and fluctuation with high impact force occurred as time passes. And the peak impact force showed a steeper slope and appeared more quickly, the high impact force undergoes a fluctuation with high speed, and acting on the check dam. At the mountainous upstream, strong rainfall energy provoke a repeat erosion and deposition which results in debris flow force causing much damage along the check dam at the mountainous place. The analyses of the present study help provide information to predict future debris flow force and how to design for the check dam. This research was supported by a grant [MPSS-NH-2014-74] through the Disaster and Safety Management Institute funded by Ministry of Public Safety and Security of Korean government

  7. Reduction Effect Analysis of Erosion Control Facilities Using Debris Flow Numerical Model

    Science.gov (United States)

    Jun, Kyewon; Kim, Younghwan; Oh, Chaeyeon; Lee, Hojin; Kim, SoungDoug

    2017-04-01

    With the increase in frequency of typhoons and heavy rains following the climate change, the scale of damage from the calamities in the mountainous areas has been growing larger and larger, which is different from the past. For the case of Korea where 64% of land is consisted of the mountainous areas, establishment of the check dams has been drastically increased after 2000 in order to reduce the damages from the debris flow. However, due to the lack of data on scale, location and kind of check dams established for reducing the damages in debris flow, the measures to prevent damages based on experience and subjective basis have to be relied on. This study, the high-precision DEM data was structured by using the terrestrial LiDAR in the Jecheon area where the debris flow damage occurred in July 2009. And, from the numerical models of the debris flow, Kanako-2D that is available to reflect the erosion and deposition action was applied to install the erosion control facilities (water channel, check dam) and analyzed the effect of reducing the debris flow shown in the downstream. After installing the erosion control facilities, most of debris flow moves along the water channel to reduce the area to expand the debris flow, and after installing the check dam, the flow depth and flux of the debris flow were reduced along with the erosion. However, even after constructing the erosion control facilities, damages were still inflicted on private residences or agricultural sites located on the upper regions where the deposition was made. Acknowledgments This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(NRF-2016R1D1A3B03933362)

  8. A comparative 2D modeling of debris-flow propagation and outcomes for end-users

    Science.gov (United States)

    Bettella, F.; Bertoldi, G.; Pozza, E.; McArdell, B. W.; D'Agostino, V.

    2012-04-01

    In Alpine regions gravity-driven natural hazards, in particular debris flows, endanger settlements and human life. Mitigation strategies based on hazard maps are necessary tools for land planning. These maps can be made more precise by using numerical models to forecasting the inundated areas after a careful setting of those 'key parameters' (K-P) which directly affect the flow motion and its interaction with the ground surface. Several physically based 2D models are available for practitioners and governmental agencies, but the selection criteria of model type and of the related K-P remain flexible and partly subjective. This remark has driven us to investigate how different models simulate different types of debris flows (from granular to muddy debris flows, going through intermediate types), in particular when the flow is influenced by the presence of deposition basins. Two commercial 2D physical models (RAMMS and FLO-2D) have been tested for five well-documented debris flows events from five Italian catchments were different geology and flow dynamics are observed: 1) a viscous debris flow occurred in 2009 in a catchment with a metamorphic geology (Gadria torrent, Bolzano Province); 2) the 2009 granular debris flow in an granitic geological setting (Rio Dosson, Trento Province); 3-4) two events occurred in the 'rio Val del Lago' and 'rio Molinara' (Trento Province) in 2010 where porphyritic lithology prevails (intermediate granular debris flow); 5) the Rotolon torrent (Vicenza Province) 2009 debris flow containing sedimentary rocks enclosed in an abundant clay-rich matrix (intermediate viscous case). Event volumes range from 5.000 to 50.000 cubic meters. The Gadria, Rotolon and Val del Lago events are also influenced by artificial retention basins. Case study simulations allowed delineation of some practical end-user suggestions and good practices in order to guide the model choice and the K-P setting, particularly related to different flow dynamics. The

  9. The earth orbiting space debris

    Directory of Open Access Journals (Sweden)

    Rossi A.

    2005-01-01

    Full Text Available The space debris population is similar to the asteroid belt, since it is subject to a process of high-velocity mutual collisions that affects the long-term evolution of its size distribution. Presently, more than 10 000 artificial debris particles with diameters larger than 10 cm (and more than 300 000 with diameters larger than 1 cm are orbiting the Earth, and are monitored and studied by a large network of sensors around the Earth. Many objects of different kind compose the space debris population, produced by different source mechanisms ranging from high energy fragmentation of large spacecraft to slow diffusion of liquid metal. The impact against a space debris is a serious risk that every spacecraft must face now and it can be evaluated with ad-hoc algorithms. The long term evolution of the whole debris population is studied with computer models allowing the simulation of all the known source and sink mechanisms. One of these codes is described in this paper and the evolution of the debris environment over the next 100 years, under different traffic scenarios, is shown, pointing out the possible measures to mitigate the growth of the orbital debris population. .

  10. Debris flow run-out simulation and analysis using a dynamic model

    Science.gov (United States)

    Melo, Raquel; van Asch, Theo; Zêzere, José L.

    2018-02-01

    Only two months after a huge forest fire occurred in the upper part of a valley located in central Portugal, several debris flows were triggered by intense rainfall. The event caused infrastructural and economic damage, although no lives were lost. The present research aims to simulate the run-out of two debris flows that occurred during the event as well as to calculate via back-analysis the rheological parameters and the excess rain involved. Thus, a dynamic model was used, which integrates surface runoff, concentrated erosion along the channels, propagation and deposition of flow material. Afterwards, the model was validated using 32 debris flows triggered during the same event that were not considered for calibration. The rheological and entrainment parameters obtained for the most accurate simulation were then used to perform three scenarios of debris flow run-out on the basin scale. The results were confronted with the existing buildings exposed in the study area and the worst-case scenario showed a potential inundation that may affect 345 buildings. In addition, six streams where debris flow occurred in the past and caused material damage and loss of lives were identified.

  11. Combining Spatial Models for Shallow Landslides and Debris-Flows Prediction

    Directory of Open Access Journals (Sweden)

    Eurípedes Vargas do Amaral

    2013-05-01

    Full Text Available Mass movements in Brazil are common phenomena, especially during strong rainfall events that occur frequently in the summer season. These phenomena cause losses of lives and serious damage to roads, bridges, and properties. Moreover, the illegal occupation by slums on the slopes around the cities intensifies the effect of the mass movement. This study aimed to develop a methodology that combines models of shallow landslides and debris-flows in order to create a map with landslides initiation and debris-flows volume and runout distance. The study area comprised of two catchments in Rio de Janeiro city: Quitite and Papagaio that drained side by side the west flank of the Maciço da Tijuca, with an area of 5 km2. The method included the following steps: (a location of the susceptible areas to landslides using SHALSTAB model; (b determination of rheological parameters of debris-flow from the back-analysis technique; and (c combination of SHALSTAB and FLO-2D models to delineate the areas more susceptible to mass movements. These scenarios were compared with the landslide and debris-flow event of February 1996. Many FLO-2D simulations were exhaustively made to estimate the rheological parameters from the back-analysis technique. Those rheological coefficients of single simulation were back-calculated by adjusting with area and depth of the debris-flow obtained from field data. The initial material volume in the FLO-2D simulations was estimated from SHALSTAB model. The combination of these two mathematical models, SHALSTAB and FLO-2D, was able to predict both landslides and debris-flow events. Such procedures can reduce the casualties and property damage, delineating hazard areas, to estimate hazard intensities for input into risk studies providing information for public policy and planning.

  12. A grid-based model of backwasting of supraglacial ice cliffs over debris-covered glaciers

    NARCIS (Netherlands)

    Buri, Pascal; Pellicciotti, Francesca; Steiner, Jakob F|info:eu-repo/dai/nl/119338653; Miles, Evan S.; Immerzeel, Wouter W|info:eu-repo/dai/nl/290472113

    2016-01-01

    Ice cliffs might be partly responsible for the high mass losses of debris-covered glaciers in the Hindu Kush-Karakoram-Himalaya region. The few existing models of cliff backwasting are point-scale models applied at few locations or assume cliffs to be planes with constant slope and aspect, a major

  13. Historical Account to the State of the Art in Debris Flow Modeling

    Science.gov (United States)

    Pudasaini, Shiva P.

    2013-04-01

    In this contribution, I present a historical account of debris flow modelling leading to the state of the art in simulations and applications. A generalized two-phase model is presented that unifies existing avalanche and debris flow theories. The new model (Pudasaini, 2012) covers both the single-phase and two-phase scenarios and includes many essential and observable physical phenomena. In this model, the solid-phase stress is closed by Mohr-Coulomb plasticity, while the fluid stress is modeled as a non-Newtonian viscous stress that is enhanced by the solid-volume-fraction gradient. A generalized interfacial momentum transfer includes viscous drag, buoyancy and virtual mass forces, and a new generalized drag force is introduced to cover both solid-like and fluid-like drags. Strong couplings between solid and fluid momentum transfer are observed. The two-phase model is further extended to describe the dynamics of rock-ice avalanches with new mechanical models. This model explains dynamic strength weakening and includes internal fluidization, basal lubrication, and exchanges of mass and momentum. The advantages of the two-phase model over classical (effectively single-phase) models are discussed. Advection and diffusion of the fluid through the solid are associated with non-linear fluxes. Several exact solutions are constructed, including the non-linear advection-diffusion of fluid, kinematic waves of debris flow front and deposition, phase-wave speeds, and velocity distribution through the flow depth and through the channel length. The new model is employed to study two-phase subaerial and submarine debris flows, the tsunami generated by the debris impact at lakes/oceans, and rock-ice avalanches. Simulation results show that buoyancy enhances flow mobility. The virtual mass force alters flow dynamics by increasing the kinetic energy of the fluid. Newtonian viscous stress substantially reduces flow deformation, whereas non-Newtonian viscous stress may change the

  14. Space Environment Modeling

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes presentation materials and outputs from operational space environment models produced by the NOAA Space Weather Prediction Center (SWPC) and...

  15. Predicting debris flow occurrence in Eastern Italian Alps based on hydrological and geomorphological modelling

    Science.gov (United States)

    Nikolopoulos, Efthymios I.; Borga, Marco; Destro, Elisa; Marchi, Lorenzo

    2015-04-01

    Most of the work so far on the prediction of debris flow occurrence is focused on the identification of critical rainfall conditions. However, findings in the literature have shown that critical rainfall thresholds cannot always accurately identify debris flow occurrence, leading to false detections (positive or negative). One of the main reasons for this limitation is attributed to the fact that critical rainfall thresholds do not account for the characteristics of underlying land surface (e.g. geomorphology, moisture conditions, sediment availability, etc), which are strongly related to debris flow triggering. In addition, in areas where debris flows occur predominantly as a result of channel bed failure (as in many Alpine basins), the triggering factor is runoff, which suggests that identification of critical runoff conditions for debris flow prediction is more pertinent than critical rainfall. The primary objective of this study is to investigate the potential of a triggering index (TI), which combines variables related to runoff generation and channel morphology, for predicting debris flows occurrence. TI is based on a threshold criterion developed on past works (Tognacca et al., 2000; Berti and Simoni, 2005; Gregoretti and Dalla Fontana, 2008) and combines information on unit width peak flow, local channel slope and mean grain size. Estimation of peak discharge is based on the application of a distributed hydrologic model, while local channel slope is derived from a high-resolution (5m) DEM. Scaling functions of peak flows and channel width with drainage area are adopted since it is not possible to measure channel width or simulate peak flow at all channel nodes. TI values are mapped over the channel network thus allowing spatially distributed prediction but instead of identifying debris flow occurrence on single points, we identify their occurrence with reference to the tributary catchment involved. Evaluation of TI is carried out for five different basins

  16. Review of the Technical Status on the Debris Bed Cooling Model

    International Nuclear Information System (INIS)

    Kim, Eui Kwang; Cho, Chung Ho; Lee, Yong Bum

    2007-09-01

    Preliminary safety analyses of the KALIMER-600 design have shown that the design has inherent safety characteristics and is capable of accommodating double-fault initiators such as ATWS events without coolant boiling or fuel melting. However, for the future design of sodium cooled fast reactor, the evaluation of the safety performance and the determination of containment requirements may be worth due consideration of triple-fault accident sequences of extremely low probability of occurrence that leads to core melting. For any postulated accident sequence which leads to core melting, in-vessel retention of the core debris will be required as a design requirement for the future design of sodium cooled fast reactor. Also, proof of the capacity of the debris bed cooling is an essential condition to solve the problem of in-vessel retention of the core debris. In this study, review of the technical status on the debris bed cooling model was carried out for in-vessel retention of the core debris

  17. Propagation of a channelized debris-flow: experimental investigation and parameters identification for numerical modelling

    Science.gov (United States)

    Termini, Donatella

    2013-04-01

    Recent catastrophic events due to intense rainfalls have mobilized large amount of sediments causing extensive damages in vast areas. These events have highlighted how debris-flows runout estimations are of crucial importance to delineate the potentially hazardous areas and to make reliable assessment of the level of risk of the territory. Especially in recent years, several researches have been conducted in order to define predicitive models. But, existing runout estimation methods need input parameters that can be difficult to estimate. Recent experimental researches have also allowed the assessment of the physics of the debris flows. But, the major part of the experimental studies analyze the basic kinematic conditions which determine the phenomenon evolution. Experimental program has been recently conducted at the Hydraulic laboratory of the Department of Civil, Environmental, Aerospatial and of Materials (DICAM) - University of Palermo (Italy). The experiments, carried out in a laboratory flume appositely constructed, were planned in order to evaluate the influence of different geometrical parameters (such as the slope and the geometrical characteristics of the confluences to the main channel) on the propagation phenomenon of the debris flow and its deposition. Thus, the aim of the present work is to give a contribution to defining input parameters in runout estimation by numerical modeling. The propagation phenomenon is analyzed for different concentrations of solid materials. Particular attention is devoted to the identification of the stopping distance of the debris flow and of the involved parameters (volume, angle of depositions, type of material) in the empirical predictive equations available in literature (Rickenmanm, 1999; Bethurst et al. 1997). Bethurst J.C., Burton A., Ward T.J. 1997. Debris flow run-out and landslide sediment delivery model tests. Journal of hydraulic Engineering, ASCE, 123(5), 419-429 Rickenmann D. 1999. Empirical relationships

  18. Modelling Subaqueous Debris Flows - A comparison of two state-of-the-art integrated models

    Science.gov (United States)

    Spinewine, Benoit; Sfouni-Grigoriadou, Mariangela; Ingarfield, Samuel

    2015-04-01

    With the gradual depletion of nearshore resources and technological advances in oil and gas production, developments are now often located beyond the continental shelf in environments susceptible to mass movement events. The risk to subsea infrastructure from these events is often quantified through: i) an assessment of potential unstable slope areas and ii) numerical modelling of the potential slide runout behaviour. This submission compares two different state-of-the-art depth-averaged numerical models for debris flow runout. These models both incorporate advanced rheology modelling and are capable of modelling slide behaviour over complex 3D bathymetry, but solve the governing equations in two drastically differing fashions - the first of which solves these equations within an Eulerian, Finite Volume framework, whilst the second solves the equations within a Lagrangian framework through a technique known as Smoothed Particle Hydrodynamics (SPH). The relationship between shear stress and shear strain rate is modelled using either the linear viscoplastic Bingham or non-linear viscoplastic Herschel-Bulkley model. These numerical models also have a facility for the modelling of soil strength degradation during runout as a consequence of remoulding, as well as through the entrainment of ambient fluid. The soil mass itself is modelled as a rigid plug layer with an internal shear strain rate of zero, overlying a sheared layer where the shear stress at the interface between these layers is equal to the yield stress of the soil. The velocity in the plug layer is constant throughout its depth, whilst in the sheared layer it gradually diminishes to zero. The Eurlerian model relies on an unstructured triangular mesh for the representation of the bathymetry. This is constructed using a generator which provides for local refinement in the area of anticipated runout and along steeper slopes or channelised areas. The equations are solved using a finite volume approach, using a

  19. The application of numerical debris flow modelling for the generation of physical vulnerability curves

    Directory of Open Access Journals (Sweden)

    B. Quan Luna

    2011-07-01

    Full Text Available For a quantitative assessment of debris flow risk, it is essential to consider not only the hazardous process itself but also to perform an analysis of its consequences. This should include the estimation of the expected monetary losses as the product of the hazard with a given magnitude and the vulnerability of the elements exposed. A quantifiable integrated approach of both hazard and vulnerability is becoming a required practice in risk reduction management. This study aims at developing physical vulnerability curves for debris flows through the use of a dynamic run-out model. Dynamic run-out models for debris flows are able to calculate physical outputs (extension, depths, velocities, impact pressures and to determine the zones where the elements at risk could suffer an impact. These results can then be applied to consequence analyses and risk calculations. On 13 July 2008, after more than two days of intense rainfall, several debris and mud flows were released in the central part of the Valtellina Valley (Lombardy Region, Northern Italy. One of the largest debris flows events occurred in a village called Selvetta. The debris flow event was reconstructed after extensive field work and interviews with local inhabitants and civil protection teams. The Selvetta event was modelled with the FLO-2D program, an Eulerian formulation with a finite differences numerical scheme that requires the specification of an input hydrograph. The internal stresses are isotropic and the basal shear stresses are calculated using a quadratic model. The behaviour and run-out of the flow was reconstructed. The significance of calculated values of the flow depth, velocity, and pressure were investigated in terms of the resulting damage to the affected buildings. The physical damage was quantified for each affected structure within the context of physical vulnerability, which was calculated as the ratio between the monetary loss and the reconstruction value. Three

  20. Debris flow analysis with a one dimensional dynamic run-out model that incorporates entrained material

    Science.gov (United States)

    Luna, Byron Quan; Remaître, Alexandre; van Asch, Theo; Malet, Jean-Philippe; van Westen, Cees

    2010-05-01

    Estimating the magnitude and the intensity of rapid landslides like debris flows is fundamental to evaluate quantitatively the hazard in a specific location. Intensity varies through the travelled course of the flow and can be described by physical features such as deposited volume, velocities, height of the flow, impact forces and pressures. Dynamic run-out models are able to characterize the distribution of the material, its intensity and define the zone where the elements will experience an impact. These models can provide valuable inputs for vulnerability and risk calculations. However, most dynamic run-out models assume a constant volume during the motion of the flow, ignoring the important role of material entrained along its path. Consequently, they neglect that the increase of volume enhances the mobility of the flow and can significantly influence the size of the potential impact area. An appropriate erosion mechanism needs to be established in the analyses of debris flows that will improve the results of dynamic modeling and consequently the quantitative evaluation of risk. The objective is to present and test a simple 1D debris flow model with a material entrainment concept based on limit equilibrium considerations and the generation of excess pore water pressure through undrained loading of the in situ bed material. The debris flow propagation model is based on a one dimensional finite difference solution of a depth-averaged form of the Navier-Stokes equations of fluid motions. The flow is treated as a laminar one phase material, which behavior is controlled by a visco-plastic Coulomb-Bingham rheology. The model parameters are evaluated and the model performance is tested on a debris flow event that occurred in 2003 in the Faucon torrent (Southern French Alps).

  1. TRENT2D WG: a smart web infrastructure for debris-flow modelling and hazard assessment

    Science.gov (United States)

    Zorzi, Nadia; Rosatti, Giorgio; Zugliani, Daniel; Rizzi, Alessandro; Piffer, Stefano

    2016-04-01

    Mountain regions are naturally exposed to geomorphic flows, which involve large amounts of sediments and induce significant morphological modifications. The physical complexity of this class of phenomena represents a challenging issue for modelling, leading to elaborate theoretical frameworks and sophisticated numerical techniques. In general, geomorphic-flows models proved to be valid tools in hazard assessment and management. However, model complexity seems to represent one of the main obstacles to the diffusion of advanced modelling tools between practitioners and stakeholders, although the UE Flood Directive (2007/60/EC) requires risk management and assessment to be based on "best practices and best available technologies". Furthermore, several cutting-edge models are not particularly user-friendly and multiple stand-alone software are needed to pre- and post-process modelling data. For all these reasons, users often resort to quicker and rougher approaches, leading possibly to unreliable results. Therefore, some effort seems to be necessary to overcome these drawbacks, with the purpose of supporting and encouraging a widespread diffusion of the most reliable, although sophisticated, modelling tools. With this aim, this work presents TRENT2D WG, a new smart modelling solution for the state-of-the-art model TRENT2D (Armanini et al., 2009, Rosatti and Begnudelli, 2013), which simulates debris flows and hyperconcentrated flows adopting a two-phase description over a mobile bed. TRENT2D WG is a web infrastructure joining advantages offered by the software-delivering model SaaS (Software as a Service) and by WebGIS technology and hosting a complete and user-friendly working environment for modelling. In order to develop TRENT2D WG, the model TRENT2D was converted into a service and exposed on a cloud server, transferring computational burdens from the user hardware to a high-performing server and reducing computational time. Then, the system was equipped with an

  2. A global map of supraglacial debris cover and recent debris area changes

    Science.gov (United States)

    Herreid, S.; Pellicciotti, F.

    2017-12-01

    The extent of supraglacial rock debris is both a first order indicator of the rock flux within a glacier system and an important term in glacier mass balance models where debris cover modulates the energy fluxes that reach the buried glacier ice surface. To date, no global debris cover inventory is available and most global models of glacier change do not include the effect of debris cover on mass balance. We have used Landsat data and glacier outlines from the Randolph Glacier Inventory v6.0 and PROMICE (Programme for Monitoring of the Greenland Ice Sheet) to generate a modern-date global inventory of debris cover at a spatial resolution of 30 m. For select locations around the Earth with high concentrations of glacier ice and suitable historical imagery, we have derived changes in debris-covered area. We present the heterogeneous pattern of debris cover on Earth which is the integrated signal from hundreds of years of rock debris accumulation and transportation through each glacier system. We further resolve this debris history by presenting recent changes in debris-covered area over the satellite era. Preliminary results from Southeast Alaska, USA, Baffin Island, Canada, Southeast Greenland, and the Eastern Himalaya, China all show an increase in debris-covered area over the past tens of years with heterogeneous rates of increase. This study provides a greater geomorphological understanding of glaciers, their surrounding environment and the flux of supraglacial debris at timescales of both hundreds and tens of years. These data also serve as an input dataset and/or an indicator pointing to locations where debris cover needs to be considered in glacier melt models.

  3. The application of numerical debris flow modelling for the generation of physical vulnerability curves

    Czech Academy of Sciences Publication Activity Database

    Quan Luna, B.; Blahůt, Jan; van Westen, C.J.; Sterlacchini, S.; van Asch, T.W.J.; Akbas, S.O.

    2011-01-01

    Roč. 11, č. 7 (2011), s. 2047-2060 ISSN 1561-8633 Institutional research plan: CEZ:AV0Z30460519 Keywords : debris flow modelling * hazard * vulnerability curves Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.983, year: 2011 http://www.nat-hazards-earth-syst-sci.net/11/2047/2011/

  4. A physically based 3-D model of ice cliff evolution over debris-covered glaciers

    NARCIS (Netherlands)

    Buri, Pascal; Miles, Evan S.; Steiner, J.F.; Immerzeel, W.W.; Wagnon, Patrick; Pellicciotti, Francesca

    2016-01-01

    We use high-resolution digital elevation models (DEMs) from unmanned aerial vehicle (UAV) surveys to document the evolution of four ice cliffs on the debris-covered tongue of Lirung Glacier, Nepal, over one ablation season. Observations show that out of four cliffs, three different patterns of

  5. Modelling of Structural Loads in Drag Augmented Space Debris Removal Concepts

    DEFF Research Database (Denmark)

    Kristensen, Anders Schmidt; Nikolajsen, Jan Ánike; Lauridsen, Peter Riddersholm

    2017-01-01

    A Self-deployable Deorbiting Space Structure (SDSS) is used for drag augmented space debris removal. A highly flexible frame allows for a folding of the structure by bifurcation. This research models the structural loads during the deployment and unfolding of the drag sail in Low Earth Orbit (LEO...

  6. Rapid Charged Geosynchronous Debris Perturbation Modeling of Electrodynamic Disturbances

    Science.gov (United States)

    Hughes, Joseph; Schaub, Hanspeter

    2018-04-01

    Charged space objects experience small perturbative torques and forces from their interaction with Earth's magnetic field. These small perturbations can change the orbits of lightweight, uncontrolled debris objects dramatically even over short periods. This paper investigates the effects of the isolated Lorentz force, the effects of including or neglecting this and other electromagnetic perturbations in a full propagation, and then analyzes for which objects electromagnetic effects have the most impact. It is found that electromagnetic forces have a negligible impact on their own. However, if the center of charge is not collocated with the center of mass, electromagnetic torques are produced which do impact the attitude, and thus the position by affecting the direction and magnitude of the solar radiation pressure force. The objects for which electrostatic torques have the most influence are charged above the kilovolt level, have a difference between their center of mass and center of charge, have highly attitude-dependent cross-sectional area, and are not spinning stably about an axis of maximum inertia. Fully coupled numerical simulation illustrate the impact of electromagnetic disturbances through the solar radiation pressure coupling.

  7. CFD-modeling of insulation debris transport phenomena in water flow

    Energy Technology Data Exchange (ETDEWEB)

    Krepper, Eckhard, E-mail: E.Krepper@fzd.d [Forschungszentrum Dresden-Rossendorf, Institute of Safety Research, Bautzner Landstrasse 128, 01328 Dresden (Germany); Cartland-Glover, Gregory; Grahn, Alexander; Weiss, Frank-Peter [Forschungszentrum Dresden-Rossendorf, Institute of Safety Research, Bautzner Landstrasse 128, 01328 Dresden (Germany); Alt, Soeren; Hampel, Rainer; Kaestner, Wolfgang; Seeliger, Andre [University of Applied Sciences Zittau/Goerlitz (FH), Theodor-Koerner-Allee 16, 02763 Zittau (Germany)

    2010-09-15

    The investigation of insulation debris generation, transport and sedimentation becomes important with regard to reactor safety research for PWR and BWR, when considering the long-term behavior of emergency core cooling systems during all types of loss of coolant accidents (LOCA). The insulation debris released near the break during a LOCA incident consists of a mixture of disparate particle population that varies with size, shape, consistency and other properties. Some fractions of the released insulation debris can be transported into the reactor sump, where it may perturb/impinge on the emergency core cooling systems. Open questions of generic interest are the sedimentation of the insulation debris in a water pool, its possible re-suspension and transport in the sump water flow and the particle load on strainers and corresponding pressure drop. A joint research project on such questions is being performed in cooperation between the University of Applied Sciences Zittau/Goerlitz and the Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation of particle transport phenomena in coolant flow and the development of CFD models for its description. While the experiments are performed at the University at Zittau/Goerlitz, the theoretical modeling efforts are concentrated at Forschungszentrum Dresden-Rossendorf. In the current paper the basic concepts for CFD-modeling are described and feasibility studies including the conceptual design of the experiments are presented.

  8. Long-Term Sorption of Metals Is Similar among Plastic Types: Implications for Plastic Debris in Aquatic Environments

    Science.gov (United States)

    Rochman, Chelsea M.; Hentschel, Brian T.; Teh, Swee J.

    2014-01-01

    Concerns regarding plastic debris and its ability to accumulate large concentrations of priority pollutants in the aquatic environment led us to quantify relationships between different types of mass-produced plastic and metals in seawater. At three locations in San Diego Bay, we measured the accumulation of nine targeted metals (aluminum, chromium, manganese, iron, cobalt, nickel, zinc, cadmium and lead) sampling at 1, 3, 6, 9 and 12 months, to five plastic types: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP). Accumulation patterns were not consistent over space and time, and in general all types of plastic tended to accumulate similar concentrations of metals. When we did observe significant differences among concentrations of metals at a single sampling period or location in San Diego Bay, we found that HDPE typically accumulated lesser concentrations of metals than the other four polymers. Furthermore, over the 12-month study period, concentrations of all metals increased over time, and chromium, manganese, cobalt, nickel, zinc and lead did not reach saturation on at least one plastic type during the entire 12-month exposure. This suggests that plastic debris may accumulate greater concentrations of metals the longer it remains at sea. Overall, our work shows that a complex mixture of metals, including those listed as priority pollutants by the US EPA (Cd, Ni, Zn and Pb), can be found on plastic debris composed of various plastic types. PMID:24454866

  9. Long-term sorption of metals is similar among plastic types: implications for plastic debris in aquatic environments.

    Directory of Open Access Journals (Sweden)

    Chelsea M Rochman

    Full Text Available Concerns regarding plastic debris and its ability to accumulate large concentrations of priority pollutants in the aquatic environment led us to quantify relationships between different types of mass-produced plastic and metals in seawater. At three locations in San Diego Bay, we measured the accumulation of nine targeted metals (aluminum, chromium, manganese, iron, cobalt, nickel, zinc, cadmium and lead sampling at 1, 3, 6, 9 and 12 months, to five plastic types: polyethylene terephthalate (PET, high-density polyethylene (HDPE, polyvinyl chloride (PVC, low-density polyethylene (LDPE, and polypropylene (PP. Accumulation patterns were not consistent over space and time, and in general all types of plastic tended to accumulate similar concentrations of metals. When we did observe significant differences among concentrations of metals at a single sampling period or location in San Diego Bay, we found that HDPE typically accumulated lesser concentrations of metals than the other four polymers. Furthermore, over the 12-month study period, concentrations of all metals increased over time, and chromium, manganese, cobalt, nickel, zinc and lead did not reach saturation on at least one plastic type during the entire 12-month exposure. This suggests that plastic debris may accumulate greater concentrations of metals the longer it remains at sea. Overall, our work shows that a complex mixture of metals, including those listed as priority pollutants by the US EPA (Cd, Ni, Zn and Pb, can be found on plastic debris composed of various plastic types.

  10. Long-term sorption of metals is similar among plastic types: implications for plastic debris in aquatic environments.

    Science.gov (United States)

    Rochman, Chelsea M; Hentschel, Brian T; Teh, Swee J

    2014-01-01

    Concerns regarding plastic debris and its ability to accumulate large concentrations of priority pollutants in the aquatic environment led us to quantify relationships between different types of mass-produced plastic and metals in seawater. At three locations in San Diego Bay, we measured the accumulation of nine targeted metals (aluminum, chromium, manganese, iron, cobalt, nickel, zinc, cadmium and lead) sampling at 1, 3, 6, 9 and 12 months, to five plastic types: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP). Accumulation patterns were not consistent over space and time, and in general all types of plastic tended to accumulate similar concentrations of metals. When we did observe significant differences among concentrations of metals at a single sampling period or location in San Diego Bay, we found that HDPE typically accumulated lesser concentrations of metals than the other four polymers. Furthermore, over the 12-month study period, concentrations of all metals increased over time, and chromium, manganese, cobalt, nickel, zinc and lead did not reach saturation on at least one plastic type during the entire 12-month exposure. This suggests that plastic debris may accumulate greater concentrations of metals the longer it remains at sea. Overall, our work shows that a complex mixture of metals, including those listed as priority pollutants by the US EPA (Cd, Ni, Zn and Pb), can be found on plastic debris composed of various plastic types.

  11. Parametric Effects of Debris Source, Environments, and Design Options on the Overall Performance of ECCS Recirculation Sump

    International Nuclear Information System (INIS)

    Park, Jong Woon; Kim, Chang Hyun

    2006-01-01

    A primary safety issue regarding long-term recirculation core cooling following a LOCA (Loss of Coolant Accident) is that LOCA-generated debris may be transported to the recirculation sump screen, resulting in adverse blockage on the sump screen and deterioration of available NPSH (Net Positive Suction Head) of ECCS (Emergency Core Cooling System). USNRC identified this as Generic Safety Issue (GSI) 191 and issued the Generic Letter 04-02 to resolve the issue. The GL required that all PWR owners perform an engineering assessment of their containment recirculation sumps to ensure they will not suffer from excessive blockage. The guidance report (GR) for PWR sump performance evaluation has been developed by NEI (Nuclear Energy Institute) and approved by the USNRC. In Korea, Korea Hydro and Nuclear Power Company (KHNP) is performing the assessment of Kori unit 1 and planning for remaining plants in the near future. The objective of the assessment is to derive required plant modifications including insulation, sump screen, etc. To derive the cost-effective modification items, we have to get insight on the parametric effects of plant conditions and design. Therefore, the general effects of debris source, containment environments and debris interceptor on the performance of ECCS recirculation sump with respect to head loss are parametrically investigated

  12. An integrated model to assess critical rain fall thresholds for the critical run-out distances of debris flows

    NARCIS (Netherlands)

    van Asch, Th.W.J.|info:eu-repo/dai/nl/304839558; Tang, C.; Alkema, D.; Zhu, J.; Zhou, W.

    2013-01-01

    A dramatic increase in debris flows occurred in the years after the 2008 Wenchuan earthquake in SW China due to the deposition of loose co-seismic landslide material. This paper proposes a preliminary integrated model, which describes the relationship between rain input and debris flow run-out in

  13. A distinct element approach to model the interaction between debris avalanches and embankments

    Science.gov (United States)

    Salciarini, Diana; Tamagnini, Claudio; Conversini, Pietro; Rapinesi, Silvia

    2010-05-01

    Protective measures against hazards associated with debris flows and debris avalanches, include a variety of barriers such as rock/boulder fences, deflection berms, gabions and earthfill barriers, which are placed along the potential flow path where the debris is transported and deposited or close to infrastructures potentially at risk. Recent progress in the field of numerical methods for the lagrangian analysis of discrete particulate systems provides an opportunity to develop a rational design strategy for earthfill barriers as well as other protection methods against debris avalanches. In this work, the Discrete Element Method (DEM) has been used to model the interaction between such natural phenomena and embankments. In the DEM approach, the motion of a granular mass subject to gravity is simulated by numerically solving Newton's equation of motion for each particle considered as an individual body. A parametric study based on a case-history from a marginally stable rock slope near Assisi, in central Italy, has been conducted. The embankment has been simulated in two different ways. In the first case, the embankment acts as a rigid body. In this case, a series of DEM simulations has been conducted to investigate the effect of the influence of the geometry of the sliding mass, slope and barrier, and strength properties of the granular mass on the main design parameters for the barrier. Results show that the barriers considered are all effective in retaining the debris mass; less than 6% of the initial rock mass passes the barrier. The predicted efficiency of the barriers is primarily affected by: i) barrier height; ii) run-out distance; iii) macroscopic friction angle of the debris; and, iv) size of the storage area left between the barrier and the slope base. For the limited range of values considered, the slope angle has only a minor impact on the computed results. In the second case the embankment has been treated as a deformable body, which can slide at the

  14. Modeling the Long-Term Evolution of Supraglacial Ice Cliffs on Himalayan Debris-Covered Glaciers

    Science.gov (United States)

    Buri, P.; Miles, E. S.; Steiner, J. F.; Ragettli, S.; Pellicciotti, F.

    2016-12-01

    Supraglacial ice cliffs are present on debris-covered glaciers worldwide and provide the only direct atmosphere-ice interface over the lower sections of these glaciers. Low albedo and high longwave emissions from surrounding debris cause very high melt rates, accounting for a significant portion of total glacier mass loss. As a result, ice cliffs affect glacier downwasting and mass balance. Additionally, and in contrast to the debris-covered ice, high melt at cliffs turns them into dynamic features, directly affecting glacier surface evolution. While conceptual ideas about the formation, evolution and collapse of ice cliffs exist, their life cycles have never been thoroughly documented. Based on observations obtained from high-resolution aerial and terrestrial images analyzed with Structure-from-Motion and with data from automatic weather stations on two glaciers in the Nepalese Himalaya, we simulate the evolution of selected ice cliffs over several seasons using a new physically-based model of cliff backwasting. The 3D model calculates the energy-balance at the cliff scale and includes the cliff interaction with supraglacial ponds and reburial by debris. We consider cliffs of different shape, orientation and slope, and we show that backwasting leads to a variety of evolution typologies, with cliffs that maintain a constant, self-similar geometry, cliffs that grow laterally and cliffs that disappear through slope shallowing and debris melt-out. Most cliffs persist over several seasons. The presence of a pond appears to be the key control for cliffs to survive, while east and west facing cliffs grow because of higher radiation receipts. We use the model to test the hypothesis that south-facing cliffs do not survive. We show that most south-facing cliffs demise after one melt season on both glaciers, because of high input of solar radiation exceeding the longwave radiation receipt. For north facing features, the longwave radiation receipts at lower cliff sections

  15. Development of the Space Debris Sensor (SDS)

    Science.gov (United States)

    Hamilton, J.; Liou, J.-C.; Anz-Meador, P. D.; Corsaro, B.; Giovane, F.; Matney, M.; Christiansen, E.

    2017-01-01

    The Space Debris Sensor (SDS) is a NASA experiment scheduled to fly aboard the International Space Station (ISS) starting in 2018. The SDS is the first flight demonstration of the Debris Resistive/Acoustic Grid Orbital NASA-Navy Sensor (DRAGONS) developed and matured at NASA Johnson Space Center's Orbital Debris Program Office. The DRAGONS concept combines several technologies to characterize the size, speed, direction, and density of small impacting objects. With a minimum two-year operational lifetime, SDS is anticipated to collect statistically significant information on orbital debris ranging from 50 microns to 500 microns in size. This paper describes the features of SDS and how data from the ISS mission may be used to update debris environment models. Results of hypervelocity impact testing during the development of SDS and the potential for improvement on future sensors at higher altitudes will be reviewed.

  16. Development of the Space Debris Sensor

    Science.gov (United States)

    Hamilton, J.; Liou, J.-C.; Anz-Meador, P. D.; Corsaro, B.; Giovane, F.; Matney, M.; Christiansen, E.

    2017-01-01

    The Space Debris Sensor (SDS) is a NASA experiment scheduled to fly aboard the International Space Station (ISS) starting in 2017. The SDS is the first flight demonstration of the Debris Resistive/Acoustic Grid Orbital NASA-Navy Sensor (DRAGONS) developed and matured by the NASA Orbital Debris Program Office. The DRAGONS concept combines several technologies to characterize the size, speed, direction, and density of small impacting objects. With a minimum two-year operational lifetime, SDS is anticipated to collect statistically significant information on orbital debris ranging from 50 micron to 500 micron in size. This paper describes the SDS features and how data from the ISS mission may be used to update debris environment models. Results of hypervelocity impact testing during the development of SDS and the potential for improvement on future sensors at higher altitudes will be reviewed.

  17. Space-based detection of space debris by photometric and polarimetric characteristics

    Science.gov (United States)

    Pang, Shuxia; Wang, Hu; Lu, Xiaoyun; Shen, Yang; Pan, Yue

    2017-10-01

    The number of space debris has been increasing dramatically in the last few years, and is expected to increase as much in the future. As the orbital debris population grows, the risk of collision between debris and other orbital objects also grows. Therefore, space debris detection is a particularly important task for space environment security, and then supports for space debris modeling, protection and mitigation. This paper aims to review space debris detection systematically and completely. Firstly, the research status of space debris detection at home and abroad is presented. Then, three kinds of optical observation methods of space debris are summarized. Finally, we propose a space-based detection scheme for space debris by photometric and polarimetric characteristics.

  18. Large scale debris-flow hazard assessment: a geotechnical approach and GIS modelling

    Directory of Open Access Journals (Sweden)

    G. Delmonaco

    2003-01-01

    Full Text Available A deterministic distributed model has been developed for large-scale debris-flow hazard analysis in the basin of River Vezza (Tuscany Region – Italy. This area (51.6 km 2 was affected by over 250 landslides. These were classified as debris/earth flow mainly involving the metamorphic geological formations outcropping in the area, triggered by the pluviometric event of 19 June 1996. In the last decades landslide hazard and risk analysis have been favoured by the development of GIS techniques permitting the generalisation, synthesis and modelling of stability conditions on a large scale investigation (>1:10 000. In this work, the main results derived by the application of a geotechnical model coupled with a hydrological model for the assessment of debris flows hazard analysis, are reported. This analysis has been developed starting by the following steps: landslide inventory map derived by aerial photo interpretation, direct field survey, generation of a database and digital maps, elaboration of a DTM and derived themes (i.e. slope angle map, definition of a superficial soil thickness map, geotechnical soil characterisation through implementation of a backanalysis on test slopes, laboratory test analysis, inference of the influence of precipitation, for distinct return times, on ponding time and pore pressure generation, implementation of a slope stability model (infinite slope model and generalisation of the safety factor for estimated rainfall events with different return times. Such an approach has allowed the identification of potential source areas of debris flow triggering. This is used to detected precipitation events with estimated return time of 10, 50, 75 and 100 years. The model shows a dramatic decrease of safety conditions for the simulation when is related to a 75 years return time rainfall event. It corresponds to an estimated cumulated daily intensity of 280–330 mm. This value can be considered the hydrological triggering

  19. Risk Evaluation of Debris Flow Hazard Based on Asymmetric Connection Cloud Model

    Directory of Open Access Journals (Sweden)

    Xinyu Xu

    2017-01-01

    Full Text Available Risk assessment of debris flow is a complex problem involving various uncertainty factors. Herein, a novel asymmetric cloud model coupled with connection number was described here to take into account the fuzziness and conversion situation of classification boundary and interval nature of evaluation indicators for risk assessment of debris flow hazard. In the model, according to the classification standard, the interval lengths of each indicator were first specified to determine the digital characteristic of connection cloud at different levels. Then the asymmetric connection clouds in finite intervals were simulated to analyze the certainty degree of measured indicator to each evaluation standard. Next, the integrated certainty degree to each grade was calculated with corresponding indicator weight, and the risk grade of debris flow was determined by the maximum integrated certainty degree. Finally, a case study and comparison with other methods were conducted to confirm the reliability and validity of the proposed model. The result shows that this model overcomes the defect of the conventional cloud model and also converts the infinite interval of indicators distribution into finite interval, which makes the evaluation result more reasonable.

  20. Improvement of molten core-concrete interaction model of the debris spreading analysis model in the SAMPSON code - 15193

    International Nuclear Information System (INIS)

    Hidaka, M.; Fujii, T.; Sakai, T.

    2015-01-01

    A debris spreading analysis (DSA) module has been developed and improved. The module is used in the severe accident analysis code SAMPSON and it has models for 3-dimensional natural convection with simultaneous spreading, melting and solidification. The existing analysis method of the quasi-3D boundary transportation to simulate downward concrete erosion for evaluation of molten-core concrete interaction (MCCI) was improved to full-3D to solve, for instance, debris lateral erosion under concrete floors at the bottom of the sump pit. In the advanced MCCI model, buffer cells were defined in order to solve numerical problems in case of trammel formation. Mass, momentum, and the advection term of energy between the debris melt cells and the buffer cells are solved. On the other hand, only the heat transfer and thermal conduction are solved between the debris melt cells and the structure cells, and the crust cells and the structure cells. As a preliminary analysis, a validation calculation was performed for erosion that occurred in the core-concrete interaction (CCI-2) test in the OECD/MCCI program. Comparison between the calculation and the CCI-2 test results showed the analysis has the ability to simulate debris lateral erosion under concrete floors. (authors)

  1. Effect of the orbital debris environment on the high-energy Van Allen proton belt

    Science.gov (United States)

    Konradi, Andrei

    1988-01-01

    The lifetimes of high-energy (greater than 55 MeV) protons in the Van Allen radiation belt are calculated, assuming that in time the protons will collide with and be absorbed by particulate orbiting material. The calculations are based on the NASA/DoD Civil Needs Database for orbital debris (Gaines, 1966) and moderate assumptions of future space traffic. It is found that the lifetimes of high-energy protons below 1500 km will decrease, leading to a noticeable redution in their fluxes.

  2. Study on cooling model for debris in lower plenum and countermeasures for prevention of focusing effect

    International Nuclear Information System (INIS)

    Guan Zhonghua; Yu Hongxing; Jiang Guangming

    2008-01-01

    From the basic energy conservation equations and experimental or empirical correlations, an intact model is constructed for the thermal calculation of the core debris in the lower plenum. For verification of this model, the results of two calculations for AP600 and AP1000 plants are compared with those presented in relevant literature. The analysis highlights on the impact of the decay heat power density and the focusing effect. In order to mitigate the focusing effect, it is proposed in this paper to change the lower head profile from hemisphere to parabola. The results show that this change of lower head profile can change the heat flux distribution of the debris, and mitigate the focusing effect. (authors)

  3. Numerical modeling of debris avalanches at Nevado de Toluca (Mexico): implications for hazard evaluation and mapping

    Science.gov (United States)

    Grieco, F.; Capra, L.; Groppelli, G.; Norini, G.

    2007-05-01

    The present study concerns the numerical modeling of debris avalanches on the Nevado de Toluca Volcano (Mexico) using TITAN2D simulation software, and its application to create hazard maps. Nevado de Toluca is an andesitic to dacitic stratovolcano of Late Pliocene-Holocene age, located in central México near to the cities of Toluca and México City; its past activity has endangered an area with more than 25 million inhabitants today. The present work is based upon the data collected during extensive field work finalized to the realization of the geological map of Nevado de Toluca at 1:25,000 scale. The activity of the volcano has developed from 2.6 Ma until 10.5 ka with both effusive and explosive events; the Nevado de Toluca has presented long phases of inactivity characterized by erosion and emplacement of debris flow and debris avalanche deposits on its flanks. The largest epiclastic events in the history of the volcano are wide debris flows and debris avalanches, occurred between 1 Ma and 50 ka, during a prolonged hiatus in eruptive activity. Other minor events happened mainly during the most recent volcanic activity (less than 50 ka), characterized by magmatic and tectonic-induced instability of the summit dome complex. According to the most recent tectonic analysis, the active transtensive kinematics of the E-W Tenango Fault System had a strong influence on the preferential directions of the last three documented lateral collapses, which generated the Arroyo Grande and Zaguàn debris avalanche deposits towards E and Nopal debris avalanche deposit towards W. The analysis of the data collected during the field work permitted to create a detailed GIS database of the spatial and temporal distribution of debris avalanche deposits on the volcano. Flow models, that have been performed with the software TITAN2D, developed by GMFG at Buffalo, were entirely based upon the information stored in the geological database. The modeling software is built upon equations

  4. Plastic and Non-plastic Debris Ingestion in Three Gull Species Feeding in an Urban Landfill Environment.

    Science.gov (United States)

    Seif, S; Provencher, J F; Avery-Gomm, S; Daoust, P-Y; Mallory, M L; Smith, P A

    2017-12-27

    Plastic debris is recognized as a widespread, common and problematic environmental pollutant. An important consequence of this pollution is the ingestion of plastic debris by wildlife. Assessing the degree to which different species ingest plastics, and the potential effects of these plastics on their health are important research needs for understanding the impacts of plastic pollution. We examined debris (plastic and other types) ingestion in three sympatric overwintering gull species (Herring gulls Larus smithsonianus, Great Black-backed Gulls Larus marinus, and Iceland Gulls Larus glaucoides) to understand how debris ingestion differs among species, age classes and sexes in gulls. We also assessed how plastic burdens were associated with body condition to investigate how gulls may be affected by debris ingestion. There were no differences among the species, age classes or sexes in the incidence of debris ingestion (plastic or otherwise), the mass or number of debris pieces ingested. We found no correlation between ingested plastics burdens and individual condition. Gulls ingested plastic debris, but also showed high levels of other debris types as well, including metal, glass and building materials, including a metal piece of debris found within an abscess in the stomach. Thus, when the health effects of debris ingestion on gulls, and other species that ingest debris, is of interest, either from a physical or chemical perspective, it may be necessary to consider all debris types and not just plastic burdens as is often currently done for seabirds.

  5. On protection of freedom's solar dynamic radiator from the orbital debris environment. Part 2

    International Nuclear Information System (INIS)

    Rhatigan, J.L.

    1992-01-01

    In this paper, recent progress to better understand the environmental threat of micrometeoroid and space debris to the solar dynamic radiator for the Space Station Freedom power system is reported. The objective was to define a design which would perform to survivability requirements over the expected lifetime of the radiator. A previous paper described the approach developed to assess on-orbit survivability of the solar dynamic radiator due to micrometeoroid and space debris impacts. Preliminary analyses were presented to quantify the solar dynamic radiator survivability. These included the type of particle and particle population expected to defeat the radiator bumpering. Results of preliminary hypervelocity impact (HVI) testing performed on radiator panel samples were also presented. This paper presents results of a more extensive test program undertaken to further define the response of the solar dynamic radiator to HVI. Tests were conducted on representative radiator panels (under ambient, nonoperating conditions) over a range of particle size, particle density, impact angle, and impact velocity. Target parameters were also varied. Data indicate that analytical penetration predictions are conservative (i.e., pessimistic) for the specific configuration of the solar dynamic radiator. Test results are used to define more rigorously the solar dynamic radiator reliability with respect to HVI. Test data, analyses, and survivability results are presented

  6. On protection of freedom's solar dynamic radiator from the orbital debris environment. Part 1

    International Nuclear Information System (INIS)

    Rhatigan, J.L.

    1992-01-01

    A great deal of experimentation and analysis has been performed to quantify penetration thresholds of components which will experience orbital debris impacts. Penetration has been found to depend upon mission-specific parameters such as orbital altitude, inclination, and orientation of the component; and upon component specific parameters such as material, density, and the geometry particular to its shielding. Experimental results are highly dependent upon shield configuration and cannot be extrapolated with confidence to alternate shield configurations. Also, current experimental capabilities are limited to velocities which only approach the lower limit of predicted orbital debris velocities. Therefore, prediction of the penetrating particle size for a particular component having a complex geometry remains highly uncertain. This paper describes the approach developed to assess on-orbit survivability, and include the type of particle and particle population expected to defeat the radiator bumpering (i.e., penetrate a fluid flow tube). Results of preliminary hypervelocity impact testing performed on radiator panel samples (in the 6 to 7 km/sec velocity range) are also presented. Plans for further analyses and testing are discussed. These efforts are expected to lead to a radiator design which will perform to Space Station Freedom requirements over the expected lifetime

  7. Instrumental record of debris flow initiation during natural rainfall: Implications for modeling slope stability

    Science.gov (United States)

    Montgomery, D.R.; Schmidt, K.M.; Dietrich, W.E.; McKean, J.

    2009-01-01

    The middle of a hillslope hollow in the Oregon Coast Range failed and mobilized as a debris flow during heavy rainfall in November 1996. Automated pressure transducers recorded high spatial variability of pore water pressure within the area that mobilized as a debris flow, which initiated where local upward flow from bedrock developed into overlying colluvium. Postfailure observations of the bedrock surface exposed in the debris flow scar reveal a strong spatial correspondence between elevated piezometric response and water discharging from bedrock fractures. Measurements of apparent root cohesion on the basal (Cb) and lateral (Cl) scarp demonstrate substantial local variability, with areally weighted values of Cb = 0.1 and Cl = 4.6 kPa. Using measured soil properties and basal root strength, the widely used infinite slope model, employed assuming slope parallel groundwater flow, provides a poor prediction of hydrologie conditions at failure. In contrast, a model including lateral root strength (but neglecting lateral frictional strength) gave a predicted critical value of relative soil saturation that fell within the range defined by the arithmetic and geometric mean values at the time of failure. The 3-D slope stability model CLARA-W, used with locally observed pore water pressure, predicted small areas with lower factors of safety within the overall slide mass at sites consistent with field observations of where the failure initiated. This highly variable and localized nature of small areas of high pore pressure that can trigger slope failure means, however, that substantial uncertainty appears inevitable for estimating hydrologie conditions within incipient debris flows under natural conditions. Copyright 2009 by the American Geophysical Union.

  8. A Case Study on Hydrodynamic Modeling and Design Improvement Evaluation to Manage Debris and Sediment Interference at a Water Intake Structure

    Science.gov (United States)

    Crissman, B. J.; Cunderlik, J. M.; Wong, R. P. L.; Pinero, A.

    2017-12-01

    Waterford 3 nuclear plant, located in Killona, Louisiana, provides approximately 10% of the state's electricity need. Located along the south bank of the Mississippi River, two miles upstream of the Bonnet Carre Spillway, the plant's single pass through cooling system continuously draws up to 1,000,000 gpm water from the river. On behalf of Entergy Louisiana, the project team evaluated options to improve the aging water intake structure with chronic debris and sediment entrainment issues. The highly complex and dynamic environment in the river coupled with regulatory constraints limited available improvement options: varying river stages allow debris to overflow the intake structure, but the maximum new wall height is restricted to minimize aesthetic intrusion and alteration to levee tie-back; bow waves push debris into the downstream intake wall, but the wall needs to maintain an opening to flush debris out from the intake structure; the river delivers significant sediment load, but any proposed intake structure cannot significantly alter existing bathymetry; EPA Clean Water Act Section 316(b) limited maximum velocity at the intake structure to 0.5 fps for entrainment prevention. To expedite alternative evaluation while providing sufficient data to inform management decision, instead of developing physical models, the project team developed a two-tier approach utilizing the TELEMAC hydrodynamic program to prepare screening analysis in 2D modeling and final evaluation in 3D modeling. The model was built upon the USACE ERDC ADH model, calibrated with river gauge data and peer reviewed by ERDC. TELEMAC, developed by EDF, provides novel features for modeling improvement options, including the recommended design concept, which is a hydraulically optimized intake geometry configured to maintain uniform intake flow while streamlining river flowline for debris and sediment deflection. The design includes submerged inlets with upstream and downstream walls to block

  9. Modeling and control of a flexible space robot to capture a tumbling debris

    Science.gov (United States)

    Dubanchet, Vincent

    After 60 years of intensive satellite launches, the number of drifting objects in Earth orbits is reaching a shifting point, where human intervention is becoming necessary to reduce the threat of collision. Indeed, a 200 year forecast, known as the "Kessler syndrome", states that space access will be greatly compromised if nothing is done to address the proliferation of these debris. Scientist J.-C. Liou from the National Aeronautics and Space Administration (NASA) has shown that the current trend could be reversed if at least five massive objects, such as dead satellites or rocket upper stages, were de-orbited each year. Among the various technical concepts considered for debris removal, robotics has emerged, over the last 30 years, as one of the most promising solutions. The International Space Station (ISS) already possesses fully operational robotic arms, and other missions have explored the potential of a manipulator embedded onto a satellite. During two of the latter, key capabilities have been demonstrated for on-orbit servicing, and prove to be equally useful for the purpose of debris removal. This thesis focuses on the close range capture of a tumbling debris by a robotic arm with light-weight flexible segments. This phase includes the motion planning and the control of a space robot, in order to smoothly catch a target point on the debris. The validation of such technologies is almost impossible on Earth and leads to prohibitive costs when performed on orbit. Therefore, the modeling and simulation of flexible multi-body systems has been investigated thoroughly, and is likewise a strong contribution of the thesis. Based on these models, an experimental validation is proposed by reproducing the on-orbit kinematics on a test bench made up of two industrial manipulators and driven by a real-time dynamic simulation. In a nutshell, the thesis is built around three main parts: the modeling of a space robot, the design of control laws, and their validation on a

  10. Modeling In-Channel Debris Flow Initiation Pre- and Post-Fire within the San Gabriel Mountains, California

    Science.gov (United States)

    Zdeb, B.; Holo, S.; Palucis, M. C.; Lamb, M. P.

    2016-12-01

    Debris flows are an important geomorphic agent in transporting sediment and eroding rock in mountainous terrain, and they pose significant hazards to people and infrastructure. Debris flows initiated by runoff appear to be a dominant transport process in steep bedrock landscapes, especially where channels fill by dry ravel following wildfire, but our ability to predict where these flows will initiate within the channel network is mainly based on empirical relationships. Here we explore how precipitation rate, precipitation duration, and previously documented decreases in the median grain size following post-fire ravel accumulation affect in-channel debris flow initiation. We utilized ANUGA, a python-based hydrodynamic model, to simulate runoff depths for different storm events for several steep catchments that have recently burned within the San Gabriel Mountains, California. We model peak and average flow depths along the channel network for one-, five-, ten- and 100- year storms from which we calculate the Shield's stress. We compare the modeled Shield's stress to the critical Shield's stress for debris flow initiation by runoff along the entire channel network for both pre- and post-fire conditions. Results allow identification along the channel network where debris flows are most likely to initiate for different storm events, provides a framework for hazard-mitigation efforts, -and demonstrates how sediment transport by debris flows might be included in landscape evolution models.

  11. The Large-Scale Debris Avalanche From The Tancitaro Volcano (Mexico): Characterization And Modeling

    Science.gov (United States)

    Morelli, S.; Gigli, G.; Falorni, G.; Garduno Monroy, V. H.; Arreygue, E.

    2008-12-01

    until they disappear entirely in the most distal reaches. The granulometric analysis and the comparison between the debris avalanche of the Tancitaro and other collapses with similar morphometric features (vertical relief during runout, travel distance, volume and area of the deposit) indicate that the collapse was most likely not primed by any type of eruption, but rather triggered by a strong seismic shock that could have induced the failure of a portion of the edifice, already deeply altered by intense hydrothermal fluid circulation. It is also possible to hypothesize that mechanical fluidization may have been the mechanism controlling the long runout of the avalanche, as has been determined for other well-known events. The behavior of the Tancitaro debris avalanche was numerically modeled using the DAN-W code. By opportunely modifying the rheological parameters of the different models selectable within DAN, it was determined that the two-parameter 'Voellmy model' provides the best approximation of the avalanche movement. The Voellmy model produces the most realistic results in terms of runout distance, velocity and spatial distribution of the failed mass. Since the Tancitaro event was not witnessed directly, it is possible to infer approximate velocities only from comparisons with similar and documented events, namely the Mt. St. Helens debris avalanche occurred on May 18, 1980.

  12. Experimental modelling of core debris dispersion from the vault under a PWR pressure vessel: Part 1

    International Nuclear Information System (INIS)

    Macbeth, R.V.; Trenberth, R.

    1987-12-01

    Modelling experiments have been done on a 1/25 scale model in Perspex of the vault under a PWR pressure vessel. Various liquids have been used to simulate molten core debris assumed to have fallen on to the vault floor from a breach at the bottom of the pressure vessel. High pressure air and helium have been used to simulate the discharge of steam and gas from the breach. The dispersion of liquid via the vault access shafts has been measured. Photographs have been taken of fluid flow patterns and velocity profiles have been obtained. The requirements for further experiments are indicated. (author)

  13. A physically based 3-D model of ice cliff evolution over debris-covered glaciers

    Science.gov (United States)

    Buri, Pascal; Miles, Evan S.; Steiner, Jakob F.; Immerzeel, Walter W.; Wagnon, Patrick; Pellicciotti, Francesca

    2016-12-01

    We use high-resolution digital elevation models (DEMs) from unmanned aerial vehicle (UAV) surveys to document the evolution of four ice cliffs on the debris-covered tongue of Lirung Glacier, Nepal, over one ablation season. Observations show that out of four cliffs, three different patterns of evolution emerge: (i) reclining cliffs that flatten during the ablation season; (ii) stable cliffs that maintain a self-similar geometry; and (iii) growing cliffs, expanding laterally. We use the insights from this unique data set to develop a 3-D model of cliff backwasting and evolution that is validated against observations and an independent data set of volume losses. The model includes ablation at the cliff surface driven by energy exchange with the atmosphere, reburial of cliff cells by surrounding debris, and the effect of adjacent ponds. The cliff geometry is updated monthly to account for the modifications induced by each of those processes. Model results indicate that a major factor affecting the survival of steep cliffs is the coupling with ponded water at its base, which prevents progressive flattening and possible disappearance of a cliff. The radial growth observed at one cliff is explained by higher receipts of longwave and shortwave radiation, calculated taking into account atmospheric fluxes, shading, and the emission of longwave radiation from debris surfaces. The model is a clear step forward compared to existing static approaches that calculate atmospheric melt over an invariant cliff geometry and can be used for long-term simulations of cliff evolution and to test existing hypotheses about cliffs' survival.

  14. Woody debris transport modelling by a coupled DE-SW approach

    Science.gov (United States)

    Persi, Elisabetta; Petaccia, Gabriella; Sibilla, Stefano

    2016-04-01

    The presence of wood in rivers is gaining more and more attention: on one side, the inclusion of woody debris in streams is emphasized for its ecological benefits; on the other hand, particular attention must be paid to its management, not to affect hydraulic safety. Recent events have shown that wood can be mobilized during floodings (Comiti et al. 2008, Lange and Bezzola 2006), aggravating inundations, in particular near urban areas. For this reason, the inclusion of woody debris influence on the prediction of flooded areas is an important step toward the reduction of hydraulic risk. Numerical modelling plays an important role to this purpose. Ruiz-Villanueva et al. (2014) use a two-dimensional numerical model to calculate the kinetics of cylindrical woody debris transport, taking into account also the hydrodynamic effects of wood. The model here presented couples a Discrete Element approach (DE) for the calculation of motion of a cylindrical log with the solution of the Shallow Water Equations (SW), in order to simulate woody debris transport in a two-dimensional stream. In a first step, drag force, added mass force and side force are calculated from flow and log velocities, assuming a reference area and hydrodynamic coefficients taken from literature. Then, the equations of dynamics are solved to model the planar roto-translation of the wooden cylinder. Model results and its physical reliability are clearly affected by the values of the drag and side coefficients, which in turn depend upon log submergence and angle towards the flow direction. Experimental studies to evaluate drag and side coefficients can be found for a submerged cylinder, with various orientations (Gippel et al. 1996; Hoang et al. 2015). To extend such results to the case of a floating (non-totally submerged) cylinder, the authors performed a series of laboratory tests whose outcomes are implemented in the proposed DE-SW model, to assess the effects of these values on the dynamic of woody

  15. LEGACY - EOP Marine Debris

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data contains towed diver surveys of and weights of marine debris removed from the near shore environments of the NWHI.

  16. Resolved granular debris-flow simulations with a coupled SPH-DCDEM model

    Science.gov (United States)

    Birjukovs Canelas, Ricardo; Domínguez, José M.; Crespo, Alejandro J. C.; Gómez-Gesteira, Moncho; Ferreira, Rui M. L.

    2016-04-01

    Debris flows represent some of the most relevant phenomena in geomorphological events. Due to the potential destructiveness of such flows, they are the target of a vast amount of research (Takahashi, 2007 and references therein). A complete description of the internal processes of a debris-flow is however still an elusive achievement, explained by the difficulty of accurately measuring important quantities in these flows and developing a comprehensive, generalized theoretical framework capable of describing them. This work addresses the need for a numerical model applicable to granular-fluid mixtures featuring high spatial and temporal resolution, thus capable of resolving the motion of individual particles, including all interparticle contacts. This corresponds to a brute-force approach: by applying simple interaction laws at local scales the macro-scale properties of the flow should be recovered by upscaling. This methodology effectively bypasses the complexity of modelling the intermediate scales by resolving them directly. The only caveat is the need of high performance computing, a demanding but engaging research challenge. The DualSPHysics meshless numerical implementation, based on Smoothed Particle Hydrodynamics (SPH), is expanded with a Distributed Contact Discrete Element Method (DCDEM) in order to explicitly solve the fluid and the solid phase. The model numerically solves the Navier-Stokes and continuity equations for the liquid phase and Newton's motion equations for solid bodies. The interactions between solids are modelled with classical DEM approaches (Kruggel-Emden et al, 2007). Among other validation tests, an experimental set-up for stony debris flows in a slit check dam is reproduced numerically, where solid material is introduced trough a hopper assuring a constant solid discharge for the considered time interval. With each sediment particle undergoing tens of possible contacts, several thousand time-evolving contacts are efficiently treated

  17. A simplified model of aerosol scrubbing by a water pool overlying core debris interacting with concrete

    International Nuclear Information System (INIS)

    Powers, D.A.; Sprung, J.L.

    1993-11-01

    A classic model of aerosol scrubbing from bubbles rising through water is applied to the decontamination of gases produced during core debris interactions with concrete. The model, originally developed by Fuchs, describes aerosol capture by diffusion, sedimentation, and inertial impaction. This original model for spherical bubbles is modified to account for ellipsoidal distortion of the bubbles. Eighteen uncertain variables are identified in the application of the model to the decontamination of aerosols produced during core debris interactions with concrete by a water pool of specified depth and subcooling. These uncertain variables include properties of the aerosols, the bubbles, the water and the ambient pressure. Results are analyzed using a nonparametric, order statistical analysis that allows quantitative differentiation of stochastic and phenomenological uncertainty. The sampled values of the decontamination factors are used to construct estimated probability density functions for the decontamination factor at confidence levels of 50%, 90% and 95%. The decontamination factors for pools 30, 50, 100, 200, 300, and 500 cm deep and subcooling levels of 0, 2, 5, 10, 20, 30, 50, and 70 degrees C are correlated by simple polynomial regression. These polynomial equations can be used to estimate decontamination factors at prescribed confidence levels

  18. Assessment of Debris Flow Potential Hazardous Zones Using Numerical Models in the Mountain Foothills of Santiago, Chile

    Science.gov (United States)

    Celis, C.; Sepulveda, S. A.; Castruccio, A.; Lara, M.

    2017-12-01

    Debris and mudflows are some of the main geological hazards in the mountain foothills of Central Chile. The risk of flows triggered in the basins of ravines that drain the Andean frontal range into the capital city, Santiago, increases with time due to accelerated urban expansion. Susceptibility assessments were made by several authors to detect the main active ravines in the area. Macul and San Ramon ravines have a high to medium debris flow susceptibility, whereas Lo Cañas, Apoquindo and Las Vizcachas ravines have a medium to low debris flow susceptibility. This study emphasizes in delimiting the potential hazardous zones using the numerical simulation program RAMMS-Debris Flows with the Voellmy model approach, and the debris-flow model LAHARZ. This is carried out by back-calculating the frictional parameters in the depositional zone with a known event as the debris and mudflows in Macul and San Ramon ravines, on May 3rd, 1993, for the RAMMS approach. In the same scenario, we calibrate the coefficients to match conditions of the mountain foothills of Santiago for the LAHARZ model. We use the information obtained for every main ravine in the study area, mainly for the similarity in slopes and material transported. Simulations were made for the worst-case scenario, caused by the combination of intense rainfall storms, a high 0°C isotherm level and material availability in the basins where the flows are triggered. The results show that the runout distances are well simulated, therefore a debris-flow hazard map could be developed with these models. Correlation issues concerning the run-up, deposit thickness and transversal areas are reported. Hence, the models do not represent entirely the complexity of the phenomenon, but they are a reliable approximation for preliminary hazard maps.

  19. Modelling the global distribution and risk of small floating plastic debris

    Science.gov (United States)

    van Sebille, E.; Wilcox, C.; Lebreton, L.; Maximenko, N. A.; Sherman, P.; Hardesty, B. D.; van Franeker, J. A.; Eriksen, M.; Siegel, D.; Galgani, F.; Lavender Law, K. L.

    2016-02-01

    Microplastic debris floating at the ocean surface can harm marine life. Understanding the severity of this harm requires knowledge of plastic abundance and distributions. Dozens of expeditions measuring microplastics have been carried out since the 1970s, but they have primarily focused on the North Pacific and North Atlantic accumulation zones, with much sparser coverage elsewhere. Here, we use the largest dataset of microplastic measurements collated to date to assess the confidence we can have in global estimates of microplastic abundance and mass. We use a rigorous statistical framework to standardize a global dataset of plastic marine debris measured using surface-trawling plankton nets and coupled this with three different ocean circulation models to spatially interpolate the observations. Our estimates show that the accumulated number of microplastic particles in 2014 ranges from 15 to 51 trillion particles, weighing between 93 and 236 thousand metric tons, which is only approximately 1% of global plastic waste available to enter the ocean in the year 2010. These estimates are larger than previous global estimates, but vary widely because the scarcity of data in most of the world ocean, differences in model formulations, and fundamental knowledge gaps in the sources, transformations and fates of microplastics in the ocean. We then use this global distribution of small floating plastic debris to (i) map out where in the ocean the risk to marine life (seabirds, plankton growth) is greatest and to (ii) show that mitigation of the plastic problem can most aptly be done near coastlines, particularly in Asia, rather than in the centres of the gyres.

  20. Comparing thixotropic and Herschel–Bulkley parameterizations for continuum models of avalanches and subaqueous debris flows

    Directory of Open Access Journals (Sweden)

    C.-H. Jeon

    2018-01-01

    Full Text Available Avalanches and subaqueous debris flows are two cases of a wide range of natural hazards that have been previously modeled with non-Newtonian fluid mechanics approximating the interplay of forces associated with gravity flows of granular and solid–liquid mixtures. The complex behaviors of such flows at unsteady flow initiation (i.e., destruction of structural jamming and flow stalling (restructuralization imply that the representative viscosity–stress relationships should include hysteresis: there is no reason to expect the timescale of microstructure destruction is the same as the timescale of restructuralization. The non-Newtonian Herschel–Bulkley relationship that has been previously used in such models implies complete reversibility of the stress–strain relationship and thus cannot correctly represent unsteady phases. In contrast, a thixotropic non-Newtonian model allows representation of initial structural jamming and aging effects that provide hysteresis in the stress–strain relationship. In this study, a thixotropic model and a Herschel–Bulkley model are compared to each other and to prior laboratory experiments that are representative of an avalanche and a subaqueous debris flow. A numerical solver using a multi-material level-set method is applied to track multiple interfaces simultaneously in the simulations. The numerical results are validated with analytical solutions and available experimental data using parameters selected based on the experimental setup and without post hoc calibration. The thixotropic (time-dependent fluid model shows reasonable agreement with all the experimental data. For most of the experimental conditions, the Herschel–Bulkley (time-independent model results were similar to the thixotropic model, a critical exception being conditions with a high yield stress where the Herschel–Bulkley model did not initiate flow. These results indicate that the thixotropic relationship is promising for

  1. Trigger Analysis and Modelling of Very Large Debris Flows in Santa Teresa, Cusco, Southern Peru

    Science.gov (United States)

    Buis, Daniel; Huggel, Christian; Frey, Holger; Giráldez, Claudia; Rohrer, Mario; Christen, Marc; Portocarrero, César

    2014-05-01

    The Peruvian Andes have repeatedly been affected by large mass movements such as landslides, avalanches and debris flows. In 1998, two very large debris flows in the region of Machu Picchu (Sacsara and Ahobamba), southern Peru, destroyed the town of Santa Teresa, an important hydropower scheme and further infrastructure. The debris flows on the order of 5 to 25 million m3 volume rank among the largest recently observed events of this type worldwide. Despite their extreme dimensions, these events have not been studied in detail. An important limitation for more insight studies is the remote location of the mass flows and the very sparse information and data available for the study region. Neither triggering processes nor mass flow process characteristics have been understood to date. This study tries to fill some of these gaps in understanding that are critical to improved assessment of hazards and eventual risk reduction measures. For the trigger analysis we used data and information from field work, a limited number of ground based meteorological data, and complementary satellite derived data. Results indicate that in the case of the Sacsara event, heavy rainfall likely was a main trigger. For Ahobamba, antecedent rainfall as well as snow and ice melt leading to saturation of glacial sediments must have played an important role. Simulations with a dynamic debris flow model (RAMMS) allowed us to constrain a number of flow parameters such as flow height and velocity, runout distance and flow and deposition volumes. Strong surging flow behavior was detected, resulting in very large runout distance (exceeding 20 km); which rather depends on the largest single surge volume, not the total event volume. Based on the identification of potential mass flow sources we modeled a number of scenarios. The assessment of related hazards, including a preliminary hazard map, showed that several communities in catchments draining towards Santa Teresa are endangered by mass movements

  2. Regional approach to modeling the transport of floating plastic debris in the Adriatic Sea.

    Science.gov (United States)

    Liubartseva, S; Coppini, G; Lecci, R; Creti, S

    2016-02-15

    Sea surface concentrations of plastics and their fluxes onto coastlines are simulated over 2009-2015. Calculations incorporate combinations of terrestrial and maritime litter inputs, the Lagrangian model MEDSLIK-II forced by AFS ocean current simulations, and ECMWF wind analyses. With a relatively short particle half-life of 43.7 days, the Adriatic Sea is defined as a highly dissipative basin where the shoreline is, by construction, the main sink of floating debris. Our model results show that the coastline of the Po Delta receives a plastic flux of approximately 70 kg(km day)(-1). The most polluted sea surface area (>10 g km(-2) floating debris) is represented by an elongated band shifted to the Italian coastline and narrowed from northwest to southeast. Evident seasonality is found in the calculated plastic concentration fields and the coastline fluxes. Complex source-receptor relationships among the basin's subregions are quantified in impact matrices. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Modeling the η Corvi debris disk from the sub-AU scale to its outermost regions

    Science.gov (United States)

    Lebreton, J.; Beichman, C. A.; Bryden, G.; Defrère, D.; Mennesson, Bertr; Millan-Gabet, R.

    2014-03-01

    Dusty debris disks surrounding main sequence stars are thought to be analogues to thepopulations of small bodies of the Solar System (asteroids, comets/icy bodies and dust grains), however with often much higher masses and associated dust production rates. Mecanisms such as massive collisions or LHB-like events must therefore be invoked to justify their existence. This is especially striking for the nearby F2V star η Corvi that shows a very strong mid- and far-infrared excess despite an estimated age of ~1.4 Gyr (Lisse et al. 2012, Wyatt et al. 2005). We present new observations of the η Crv debris disk obtained in the far-infrared with Herschel/PACS and SPIRE and in the mid-infrared with the Keck Interferometer Nuller (Millan-Gabet et al. 2011). The Herschel/PACS images at 70, 100 and 160 μm reveal a well resolved belt of cold material at ~130 AU, as well as an unresolved component in the innermost parts of the system. This warmer counterpart is resolved in the mid-infrared as a strong null excess originating from within the ~2x4 AU field-of-view of the interferometer, which is reminiscent of the architecture of the Fomalhaut debris disk (Mennesson et al. 2012, Lebreton et al. 2013). The signature of warm silicate dust is also very clear in Spitzer/IRS high-resolution spectra (Chen et al. 2006) at intermediate wavelengths (10-35 μm). We undertake to establish a consistent model of the debris disk from the sub-AU scale to its outermost regions using the GRaTer radiative transfer code (Augereau et al. 1999a, Lebreton et al. 2013) by adjusting simultaneously the interferometric nulls, the resolved Herschel images and the spectro-photometric data against a large parameter space. Our analysis providesaccurate estimates of the fundamental parameters of the disk: its surface density profile, grain size distribution and mass, making it possible to unveil the origin of the dust and the relation between the cold (~50 K) Kuiper-like belt and the warm (~500 K) exo

  4. An improved method to compute supra glacial debris thickness using thermal satellite images together with an Energy Balance Model in the Nepal Himalayas

    Science.gov (United States)

    Egli, Pascal; Ayala, Alvaro; Buri, Pascal; Pellicciotti, Francesca

    2016-04-01

    A significant proportion of Himalayan glaciers is debris covered. Knowing the thickness of the debris cover is essential to obtain accurate estimates of melt rates. Due to the remoteness of these glaciers, collecting field measurements of debris thickness for a large number of glaciers is not realistic. For this reason, previous studies have proposed an approach based on computing the energy balance at the debris surface using surface temperature from satellite imagery together with meteorological data and solving the energy balance for debris thickness. These studies differ only in the way they account for the nonlinearity of debris temperature profiles and the heat stored in the debris layer. In our study we aim to 1) assess the performance of three existing models, and 2) develop a new methodology for calculating the conductive heat flux within the debris, which accounts for the history of debris temperature profiles by solving the advection-diffusion equation of heat numerically. Additionally, we found that in the previous studies several input variables are considered as uniform and we improved this by using distributed representations. As a study case we use Lirung glacier in Langtang valley, Nepal, and we work with Landsat satellite thermal images. Results are validated using measurements of debris thickness on the glacier from October 2012 and 2015. In some cases the existing models yield realistic results. But there is very little consistency between results for different satellite images. In general, computed debris thickness is frequently too thin compared to reality. Two of the existing models were able to accurately reproduce the extent of thin debris cover on the upper part of Lirung glacier. The mean debris thickness on Lirung obtained with the existing models lies between 0.1 m and 0.3 m depending on the model used, whereby the upper value of 0.3 m corresponds best to the field measurements. Preliminary results from our new model show a larger

  5. A combined morphometric, sedimentary, GIS and modelling analysis of flooding and debris flow hazard on a composite alluvial fan, Caveside, Tasmania

    Science.gov (United States)

    Kain, Claire L.; Rigby, Edward H.; Mazengarb, Colin

    2018-02-01

    Two episodes of intense flooding and sediment movement occurred in the Westmorland Stream alluvial system near Caveside, Australia in January 2011 and June 2016. The events were investigated in order to better understand the drivers and functioning of this composite alluvial system on a larger scale, so as to provide awareness of the potential hazard from future flood and debris flow events. A novel combination of methods was employed, including field surveys, catchment morphometry, GIS mapping from LiDAR and aerial imagery, and hydraulic modelling using RiverFlow-2D software. Both events were initiated by extreme rainfall events (fan. The impacts of the 2011 and 2016 events on the farmland appeared similar; however, there were differences in sediment source and transport processes that have implications for understanding recurrence probabilities. A debris flow was a key driver in the 2011 event, by eroding the stream channel in the forested watershed and delivering a large volume of sediment downstream to the alluvial fan. In contrast, modelled flooding velocities suggest the impacts of the 2016 event were the result of an extended period of extreme stream flooding and consequent erosion of alluvium directly above the current fan apex. The morphometry of the catchment is better aligned with values from fluvially dominated fans found elsewhere, which suggests that flooding represents a more frequent future risk than debris flows. These findings have wider implications for the estimation of debris flow and flood hazard on alluvial fans in Tasmania and elsewhere, as well as further demonstrating the capacity of combined hydraulic modelling and geomorphologic investigation as a predictive tool to inform hazard management practices in environments affected by flooding and sediment movement.

  6. Geospace Environment Modeling Program

    Science.gov (United States)

    Dusenbery, Paul B.; Siscoe, George L.

    1992-02-01

    The geospace environment encompasses the highest and largest of the four physical geospheres—lithosphere, hydrosphere, atmosphere, and magnetosphere. Despite its size, its far-reaching structures interconnect and move together in a choreography of organized dynamics, whose complexity is reflected in the intricate movements of the northern lights. The vastness and inaccessibility of geospace, encompassing the plasma environment of the magnetosphere/ionosphere system, and the invisibility of its structures pose great challenges to scientists who want to study its dynamics by obtaining, in effect, video tapes of its globally organized motions. A key component of their strategy is the ability to see nearly all of geospace imaged onto the top of the atmosphere. The geomagnetic field threads the volume of geospace and transmits action, TV-like, from the magnetospheric stage down its lines of force onto the atmospheric screen.

  7. Modelling Virtual Environments for Geovisualization

    DEFF Research Database (Denmark)

    Bodum, Lars

    2005-01-01

    and use of virtual environments has developed form being a rather sophisticated type of visualization that demanded extreme computer resources to become an integral part of the software on every desktop computer. This chapter addresses both philosophical and technical issues regarding the modelling......The use of virtual environments in geovisualization has become a major topic within the last few years. The main reason for this interest in the growing use of 3D models and visual realizations in a wide range of applications concerned with the geographic element of information. The implementation...... of virtual environments. It specifically focuses on different representational aspects to be taken into consideration when a virtual environment is created. These aspects are data modelling, 3D modelling and level-of-detail. A range of different approaches can be taken to visualize a virtual environment...

  8. Physically based dynamic run-out modelling for quantitative debris flow risk assessment: a case study in Tresenda, northern Italy

    Czech Academy of Sciences Publication Activity Database

    Quan Luna, B.; Blahůt, Jan; Camera, C.; Van Westen, C.; Apuani, T.; Jetten, V.; Sterlacchini, S.

    2014-01-01

    Roč. 72, č. 3 (2014), s. 645-661 ISSN 1866-6280 Institutional support: RVO:67985891 Keywords : debris flow * FLO-2D * run-out * quantitative hazard and risk assessment * vulnerability * numerical modelling Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.765, year: 2014

  9. Sensitivity of a Riparian Large Woody Debris Recruitment Model to the Number of Contributing Banks and Tree Fall Pattern

    Science.gov (United States)

    Don C. Bragg; Jeffrey L. Kershner

    2004-01-01

    Riparian large woody debris (LWD) recruitment simulations have traditionally applied a random angle of tree fall from two well-forested stream banks. We used a riparian LWD recruitment model (CWD, version 1.4) to test the validity these assumptions. Both the number of contributing forest banks and predominant tree fall direction significantly influenced simulated...

  10. Variations on Debris Disks. IV. An Improved Analytical Model for Collisional Cascades

    Science.gov (United States)

    Kenyon, Scott J.; Bromley, Benjamin C.

    2017-04-01

    We derive a new analytical model for the evolution of a collisional cascade in a thin annulus around a single central star. In this model, r max the size of the largest object changes with time, {r}\\max \\propto {t}-γ , with γ ≈ 0.1-0.2. Compared to standard models where r max is constant in time, this evolution results in a more rapid decline of M d , the total mass of solids in the annulus, and L d , the luminosity of small particles in the annulus: {M}d\\propto {t}-(γ +1) and {L}d\\propto {t}-(γ /2+1). We demonstrate that the analytical model provides an excellent match to a comprehensive suite of numerical coagulation simulations for annuli at 1 au and at 25 au. If the evolution of real debris disks follows the predictions of the analytical or numerical models, the observed luminosities for evolved stars require up to a factor of two more mass than predicted by previous analytical models.

  11. Numerical models for the analysis of thermal behavior and coolability of a particulate debris bed in reactor lower head

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Kwang Il; Kim, Sang Baik; Kim, Byung Seok [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-04-01

    This report provides three distinctive, but closely related numerical models developed for the analysis of thermal behavior and coolability of a particulate debris bed that is may be formed inside the reactor lower head during severe accident late phases. The first numerical module presented in the report, MELTPRO-DRY, is used to analyze numerically heat-up and melting process of the dry particle bed, downward- and sideward-relocation of the liquid melt under gravity force and capillary force acting among porous particles, and solidification of the liquid melt relocated into colder region. The second module, MELTPROG-WET, is used to simulate numerically the cooling process of the particulate debris bed under the existence of water, which is subjected to two types of numerical models. The first type of WET module utilizes distinctive models that parametrically simulate the water cooling process, that is, quenching region, dryout region, and transition region. The choice of each parametric model depends on temperature gradient between the cooling water and the debris particles. The second type of WET module utilizes two-phase flow model that mechanically simulates the cooling process of the debris bed. For a consistent simulation from the water cooling to the dryout debris bed, on the other hand, the aforementioned two modules, MELTPROG-DRY and MELTPROG-WET, were integrated into a single computer program DBCOOL. Each of computational models was verified through limited applications to a heat-generating particulate bed contained in the rectangular cavity. 22 refs., 5 figs., 2 tabs. (Author)

  12. Woody debris

    Science.gov (United States)

    Donna B. Scheungrab; Carl C. Trettin; Russ Lea; Martin F. Jurgensen

    2000-01-01

    Woody debris can be defined as any dead, woody plant material, including logs, branches, standing dead trees, and root wads. Woody debris is an important part of forest and stream ecosystems because it has a role in carbon budgets and nutrient cycling, is a source of energy for aquatic ecosystems, provides habitat for terrestrial and aquatic organisms, and contributes...

  13. Dynamical models to explain observations with SPHERE in planetary systems with double debris belts

    Science.gov (United States)

    Lazzoni, C.; Desidera, S.; Marzari, F.; Boccaletti, A.; Langlois, M.; Mesa, D.; Gratton, R.; Kral, Q.; Pawellek, N.; Olofsson, J.; Bonnefoy, M.; Chauvin, G.; Lagrange, A. M.; Vigan, A.; Sissa, E.; Antichi, J.; Avenhaus, H.; Baruffolo, A.; Baudino, J. L.; Bazzon, A.; Beuzit, J. L.; Biller, B.; Bonavita, M.; Brandner, W.; Bruno, P.; Buenzli, E.; Cantalloube, F.; Cascone, E.; Cheetham, A.; Claudi, R. U.; Cudel, M.; Daemgen, S.; De Caprio, V.; Delorme, P.; Fantinel, D.; Farisato, G.; Feldt, M.; Galicher, R.; Ginski, C.; Girard, J.; Giro, E.; Janson, M.; Hagelberg, J.; Henning, T.; Incorvaia, S.; Kasper, M.; Kopytova, T.; LeCoroller, H.; Lessio, L.; Ligi, R.; Maire, A. L.; Ménard, F.; Meyer, M.; Milli, J.; Mouillet, D.; Peretti, S.; Perrot, C.; Rouan, D.; Samland, M.; Salasnich, B.; Salter, G.; Schmidt, T.; Scuderi, S.; Sezestre, E.; Turatto, M.; Udry, S.; Wildi, F.; Zurlo, A.

    2018-03-01

    Context. A large number of systems harboring a debris disk show evidence for a double belt architecture. One hypothesis for explaining the gap between the debris belts in these disks is the presence of one or more planets dynamically carving it. For this reason these disks represent prime targets for searching planets using direct imaging instruments, like the Spectro-Polarimetric High-constrast Exoplanet Research (SPHERE) at the Very Large Telescope. Aim. The goal of this work is to investigate this scenario in systems harboring debris disks divided into two components, placed, respectively, in the inner and outer parts of the system. All the targets in the sample were observed with the SPHERE instrument, which performs high-contrast direct imaging, during the SHINE guaranteed time observations. Positions of the inner and outer belts were estimated by spectral energy distribution fitting of the infrared excesses or, when available, from resolved images of the disk. Very few planets have been observed so far in debris disks gaps and we intended to test if such non-detections depend on the observational limits of the present instruments. This aim is achieved by deriving theoretical predictions of masses, eccentricities, and semi-major axes of planets able to open the observed gaps and comparing such parameters with detection limits obtained with SPHERE. Methods: The relation between the gap and the planet is due to the chaotic zone neighboring the orbit of the planet. The radial extent of this zone depends on the mass ratio between the planet and the star, on the semi-major axis, and on the eccentricity of the planet, and it can be estimated analytically. We first tested the different analytical predictions using a numerical tool for the detection of chaotic behavior and then selected the best formula for estimating a planet's physical and dynamical properties required to open the observed gap. We then apply the formalism to the case of one single planet on a

  14. Material Density Distribution of Small Debris in Earth Orbit

    Science.gov (United States)

    Krisko, P. H.; Xu, Y.-l.; Opiela, J. N.; Hill, N. M.; Matney, M. J.

    2008-01-01

    Over 200 spacecraft and rocket body breakups in Earth orbit have populated that regime with debris fragments in the sub-micron through meter size range. Though the largest debris fragments can cause significant collisional damage to active (operational) spacecraft, these are few and trackable by radar. Fragments on the order of a millimeter to a centimeter in size are as yet untrackable. But this smaller debris can result in damage to critical spacecraft systems and, under the worst conditions, fragmenting collision events. Ongoing research at the NASA Orbital Debris Program Office on the sources of these small fragments has focused on the material components of spacecraft and rocket bodies and on breakup event morphology. This has led to fragment material density estimates, and also the beginnings of shape categorizations. To date the NASA Standard Breakup Model has not considered specific material density distinctions of small debris. The basis of small debris in that model is the fourth hypervelocity impact event of the Satellite Orbital Debris Characterization Impact Test (SOCIT) series. This test targeted a flight-ready, U.S. Transit navigation satellite with a solid aluminum sphere impactor. Results in this event yield characteristic length (size) and area-to-mass distributions of fragments smaller than 10 cm in the NASA model. Recent re-analysis of the SOCIT4 small fragment dataset highlighted the material-specific characteristics of metals and non-metals. Concurrent analysis of Space Shuttle in-situ impact data showed a high percentage of aluminum debris in shuttle orbit regions. Both analyses led to the definition of three main on-orbit debris material density categories -low density ( 6 g/cc). This report considers the above studies in an explicit extension of the NASA Standard Breakup Model where separate material densities for debris are generated and these debris fragments are propagated in Earth orbit. The near Earth environment is thus parameterized

  15. A two-phase debris-flow model that includes coupled evolution of volume fractions, granular dilatancy, and pore-fluid pressure

    Science.gov (United States)

    George, David L.; Iverson, Richard M.

    2011-01-01

    Pore-fluid pressure plays a crucial role in debris flows because it counteracts normal stresses at grain contacts and thereby reduces intergranular friction. Pore-pressure feedback accompanying debris deformation is particularly important during the onset of debrisflow motion, when it can dramatically influence the balance of forces governing downslope acceleration. We consider further effects of this feedback by formulating a new, depth-averaged mathematical model that simulates coupled evolution of granular dilatancy, solid and fluid volume fractions, pore-fluid pressure, and flow depth and velocity during all stages of debris-flow motion. To illustrate implications of the model, we use a finite-volume method to compute one-dimensional motion of a debris flow descending a rigid, uniformly inclined slope, and we compare model predictions with data obtained in large-scale experiments at the USGS debris-flow flume. Predictions for the first 1 s of motion show that increasing pore pressures (due to debris contraction) cause liquefaction that enhances flow acceleration. As acceleration continues, however, debris dilation causes dissipation of pore pressures, and this dissipation helps stabilize debris-flow motion. Our numerical predictions of this process match experimental data reasonably well, but predictions might be improved by accounting for the effects of grain-size segregation.

  16. Interactions of the space debris environment with mega constellations-Using the example of the OneWeb constellation

    Science.gov (United States)

    Radtke, Jonas; Kebschull, Christopher; Stoll, Enrico

    2017-02-01

    Recently, several announcements have been published to deploy satellite constellations into Low Earth Orbit (LEO) containing several hundred to thousands of rather small sized objects. The purpose of these constellations is to provide a worldwide internet coverage, even to the remotest areas. Examples of these mega-constellations are one from SpaceX, which is announced to comprise of about 4000 satellites, the Norwegian STEAM network, which is told to contain 4257 satellites, and the OneWeb constellation, which forms one of the smaller constellations with 720 satellites. As example constellation, OneWeb has been chosen. From all announced constellation, OneWeb by far delivered most information, both in regards to constellation design and their plans to encounter space debris issues, which is the reason why it has been chosen for these analyses. In this paper, at first an overview of the planned OneWeb constellation setup is given. From this description, a mission life-cycle is deduced, splitting the complete orbital lifetime of the satellites into four phases. Following, using ESA-MASTER, for each of the mission phases the flux on both single constellations satellites and the complete constellation are performed and the collision probabilities are derived. The focus in this analysis is set on catastrophic collisions. This analysis is then varied parametrically for different operational altitudes of the constellation as well as different lifetimes with different assumptions for the success of post mission disposal (PMD). Following the to-be-expected mean number of collision avoidance manoeuvres during all active mission phases is performed using ARES from ESA's DRAMA tool suite. The same variations as during the flux analysis are considered. Lastly the characteristics of hypothetical OneWeb satellite fragmentation clouds, calculated using the NASA Breakup model, are described and the impact of collision clouds from OneWeb satellites on the constellation itself is

  17. Challenges in Modeling Debris-Flow Initiation during the Exceptional September 2013 Northern Colorado Front Range Rainstorm

    Science.gov (United States)

    Baum, R. L.; Coe, J. A.; Godt, J.; Kean, J. W.

    2014-12-01

    Heavy rainfall during 9 - 13 September 2013 induced about 1100 debris flows in the foothills and mountains of the northern Colorado Front Range. Eye-witness accounts and fire-department records put the times of greatest landslide activity during the times of heaviest rainfall on September 12 - 13. Antecedent soil moisture was relatively low, particularly at elevations below 2250 m where many of the debris flows occurred, based on 45 - 125 mm of summer precipitation and absence of rainfall for about 2 weeks before the storm. Mapping from post-event imagery and field observations indicated that most debris flows initiated as small, shallow landslides. These landslides typically formed in colluvium that consisted of angular clasts in a sandy or silty matrix, depending on the nature of the parent bedrock. Weathered bedrock was partially exposed in the basal surfaces of many of the shallow source areas at depths ranging from 0.2 to 5 m, and source areas commonly occupied less than 500 m2. Although 49% of the source areas occurred in swales and 3 % in channels, where convergent flow might have contributed to pore-pressure build up during the rainfall, 48% of the source areas occurred on open slopes. Upslope contributing areas of most landslides (58%) were small (physical-properties variability. The low-moisture initial conditions require consideration of unsaturated zone effects. Ongoing fieldwork and computational modeling are aimed at addressing these challenges related to initiation of the September 2013 debris flows.

  18. TITAN2F: a pseudo-3-D model of 2-phase debris flows

    Science.gov (United States)

    Córdoba, G.; Sheridan, M. F.; Pitman, E. B.

    2015-06-01

    Debris flows, avalanches, landslides, and other geophysical mass flows can contain O(106-1010) m3 or more of material. These flows commonly consist of mixture of soil and rocks with a significant quantity of interstitial fluid. They can be tens of meters deep, and their runouts can extend many kilometers. The complicated rheology of such a mixture challenges every constitutive model that can reasonably be applied; the range of length and timescales involved in such mass flows challenges the computational capabilities of existing systems.This paper extends recent efforts to develop a depth averaged "thin layer" model for geophysical mass flows that contain a mixture of solid material and fluid. Concepts from the engineering community are integrated with phenomenological findings in geo-science, resulting in a theory that accounts for the principal solid and fluid forces as well as interactions between the phases, across a wide range of solid volume fraction. A principal contribution here is to present drag and phase interaction terms that comport with the literature in geo-sciences. The program predicts the evolution of the concentration and dynamic pressure. The theory is validated with with data from one dimensional dam break solutions and it is verified with data from artificial channel experiments.

  19. A grid-based Model for Backwasting at supraglacial Ice Cliffs on a debris-covered Glacier

    Science.gov (United States)

    Buri, P.; Steiner, J. F.; Pellicciotti, F.; Miles, E. S.; Immerzeel, W.

    2014-12-01

    In the Himalaya, debris-covered glaciers cover significant portions of the glacierised area. Their behaviour is not entirely understood, but they seem to experience strong mass losses in direct contradiction with the insulating effect of debris. A characteristic most debris-covered glaciers share is the appearance of cliffs and lakes on their surface. These supraglacial features play a role in surface evolution, dynamics and downwasting of debris-covered glaciers but their actual effects have not been quantified at the glacier scale. Numerous measurements of radiative fluxes at the cliff surface, detailed survey of cliffs geometry and ablation have been conducted on the debris-covered Lirung Glacier, Nepalese Himalayas. We used four 20cm-resolution DEMs obtained from UAV flights to represent the glacier surface to a very detailed degree. As the debris remains stable on slopes up to 30°, ice cliffs show inclinations above this threshold and were clearly represented in the DEMs. Direct measurements and a point-scale cliff-backwasting model have showed that melt patterns over a single cliff are highly variable across and along the ice surface due to non-uniform geometry, varying inclination, aspect and terrain view factors. Variability in observed ablation was large also among cliffs. We therefore developed an energy balance model with a gridded representation of the cliff to understand the melt behaviour at the cliff scale. Previous models assumed the cliff to be a plane with a constant slope and aspect, and extrapolation of melt rates to the glacier scale based on this assumption might be erroneous. Using a grid-based approach allows representation of real inclined areas of the cliff. The detailed surface from the UAV-DEM was taken as initial condition for the model. The model was in close agreement with ablation measurements at numerous stakes located on 3 cliffs. Results show very high variability both along the cliffs' elevation and extension. These cannot be

  20. Temporal variability of marine debris deposition at Tern Island in the Northwestern Hawaiian Islands.

    Science.gov (United States)

    Agustin, Alyssa E; Merrifield, Mark A; Potemra, James T; Morishige, Carey

    2015-12-15

    A twenty-two year record of marine debris collected on Tern Island is used to characterize the temporal variability of debris deposition at a coral atoll in the Northwestern Hawaiian Islands. Debris deposition tends to be episodic, without a significant relationship to local forcing processes associated with winds, sea level, waves, and proximity to the Subtropical Convergence Zone. The General NOAA Operational Modeling Environment is used to estimate likely debris pathways for Tern Island. The majority of modeled arrivals come from the northeast following prevailing trade winds and surface currents, with trajectories indicating the importance of the convergence zone, or garbage patch, in the North Pacific High region. Although debris deposition does not generally exhibit a significant seasonal cycle, some debris types contain considerable 3 cycle/yr variability that is coherent with wind and surface pressure over a broad region north of Tern. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. A depth-averaged debris-flow model that includes the effects of evolving dilatancy. I. physical basis

    Science.gov (United States)

    Iverson, Richard M.; George, David L.

    2014-01-01

    To simulate debris-flow behaviour from initiation to deposition, we derive a depth-averaged, two-phase model that combines concepts of critical-state soil mechanics, grain-flow mechanics and fluid mechanics. The model's balance equations describe coupled evolution of the solid volume fraction, m, basal pore-fluid pressure, flow thickness and two components of flow velocity. Basal friction is evaluated using a generalized Coulomb rule, and fluid motion is evaluated in a frame of reference that translates with the velocity of the granular phase, vs. Source terms in each of the depth-averaged balance equations account for the influence of the granular dilation rate, defined as the depth integral of ∇⋅vs. Calculation of the dilation rate involves the effects of an elastic compressibility and an inelastic dilatancy angle proportional to m−meq, where meq is the value of m in equilibrium with the ambient stress state and flow rate. Normalization of the model equations shows that predicted debris-flow behaviour depends principally on the initial value of m−meq and on the ratio of two fundamental timescales. One of these timescales governs downslope debris-flow motion, and the other governs pore-pressure relaxation that modifies Coulomb friction and regulates evolution of m. A companion paper presents a suite of model predictions and tests.

  2. Modified temperature index model for estimating the melt water discharge from debris-covered Lirung Glacier, Nepal

    Directory of Open Access Journals (Sweden)

    A. Parajuli

    2015-05-01

    Full Text Available In the Nepalese Himalayas, the complex topography, occurrence of debris covered glaciers, and limited data availability creates substantial difficulties for modelling glacier melt. The proper recognition of melt processes governs the accurate estimation of melt water from glacier dominated systems, even in the presence of debris-covered glaciers. This paper presents a glacier melt model developed for the Lirung sub-basin of Langtang valley, which has both a clean glacier area, 5.86 km2, and a debris-covered glacier area, 1.13 km2. We use a temperature index approach to estimate sub-daily melt water discharge for a two week period at the end of monsoon, and the melt factor is varied according to the aspect and distributed to each grid processed from the digital elevation model. The model uses easily available data and simple extrapolation techniques capable of generating melt with limited data. The result obtained from this method provides accurate estimate with an R2 value of 0.89, bias of 0.9% and Nash-Sutcliffe efficiency of 0.86, and suitable in Himalaya where data availability is major issue.

  3. The FlatModel: a 2D numerical code to evaluate debris flow dynamics. Eastern Pyrenees basins application.

    Science.gov (United States)

    Bateman, A.; Medina, V.; Hürlimann, M.

    2009-04-01

    Debris flows are present in every country where a combination of high mountains and flash floods exists. In the northern part of the Iberian Peninsula, at the Pyrenees, sporadic debris events occur. We selected two different events. The first one was triggered at La Guingueta by the big exceptional flood event that produced many debris flows in 1982 which were spread all over the Catalonian Pyrenees. The second, more local event occurred in 2000 at the mountain Montserrat at the Pre-litoral mountain chain. We present here some results of the FLATModel, entirely developed at the Research Group in Sediment Transport of the Hydraulic, Marine and Environmental Engineering Department (GITS-UPC). The 2D FLATModel is a Finite Volume method that uses the Godunov scheme. Some numerical arranges have been made to analyze the entrainment process during the events, the Stop & Go phenomena and the final deposit of the material. The material rheology implemented is the Voellmy approach, because it acts very well evaluating the frictional and turbulent behavior. The FLATModel uses a GIS environment that facilitates the data analysis as the comparison between field and numerical data. The two events present two different characteristics, one is practically a one dimensional problem of 1400 m in length and the other has a more two dimensional behavior that forms a big fan.

  4. On protection of Freedom's solar dynamic radiator from the orbital debris environment. I - Preliminary analysis and testing

    Science.gov (United States)

    Rhatigan, Jennifer L.; Christiansen, Eric L.; Fleming, Michael L.

    1992-01-01

    A great deal of experimentation and analysis was performed to quantify penetration thresholds of components which will experience orbital debris impacts. Penetration was found to depend upon mission specific parameters such as orbital altitude, inclination, and orientation of the component; and upon component specific parameters such as material, density and the geometry particular to its shielding. Experimental results are highly dependent upon shield configuration and cannot be extrapolated with confidence to alternate shield configurations. Also, current experimental capabilities are limited to velocities which only approach the lower limit of predicted orbital debris velocities. Therefore, prediction of the penetrating particle size for a particular component having a complex geometry remains highly uncertain. An approach is described which was developed to assess on-orbit survivability of the solar dynamic radiator due to micrometeoroid and space debris impacts. Preliminary analyses are presented to quantify the solar dynamic radiator survivability, and include the type of particle and particle population expected to defeat the radiator bumpering (i.e., penetrate a fluid flow tube). Results of preliminary hypervelocity impact testing performed on radiator panel samples (in the 6 to 7 km/sec velocity range) are also presented.

  5. On protection of Freedom's solar dynamic radiator from the orbital debris environment. Part 1: Preliminary analyses and testing

    Science.gov (United States)

    Rhatigan, Jennifer L.; Christiansen, Eric L.; Fleming, Michael L.

    1990-01-01

    A great deal of experimentation and analysis was performed to quantify penetration thresholds of components which will experience orbital debris impacts. Penetration was found to depend upon mission specific parameters such as orbital altitude, inclination, and orientation of the component; and upon component specific parameters such as material, density and the geometry particular to its shielding. Experimental results are highly dependent upon shield configuration and cannot be extrapolated with confidence to alternate shield configurations. Also, current experimental capabilities are limited to velocities which only approach the lower limit of predicted orbital debris velocities. Therefore, prediction of the penetrating particle size for a particular component having a complex geometry remains highly uncertain. An approach is described which was developed to assess on-orbit survivability of the solar dynamic radiator due to micrometeoroid and space debris impacts. Preliminary analyses are presented to quantify the solar dynamic radiator survivability, and include the type of particle and particle population expected to defeat the radiator bumpering (i.e., penetrate a fluid flow tube). Results of preliminary hypervelocity impact testing performed on radiator panel samples (in the 6 to 7 km/sec velocity range) are also presented. Plans for further analyses and testing are discussed. These efforts are expected to lead to a radiator design which will perform to requirements over the expected lifetime.

  6. MODELS OF THE η CORVI DEBRIS DISK FROM THE KECK INTERFEROMETER, SPITZER, AND HERSCHEL

    Energy Technology Data Exchange (ETDEWEB)

    Lebreton, J.; Beichman, C.; Millan-Gabet, R. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Bryden, G.; Mennesson, B. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91107 (United States); Defrère, D. [Department of Astronomy, University of Arizona, 993 N. Cherry Avenue, Tucson, AZ, 85721 (United States); Boccaletti, A., E-mail: lebretoj@gmail.com [LESIA, Observatoire de Paris, CNRS, University Pierre et Marie Curie Paris 6 and University Denis Diderot Paris 7, 5 place Jules Janssen, F-92195 Meudon (France)

    2016-02-01

    Debris disks are signposts of analogs to small-body populations of the solar system, often, however, with much higher masses and dust production rates. The disk associated with the nearby star η Crv is especially striking, as it shows strong mid- and far-infrared excesses despite an age of ∼1.4 Gyr. We undertake constructing a consistent model of the system that can explain a diverse collection of spatial and spectral data. We analyze Keck Interferometer Nuller measurements and revisit Spitzer and additional spectrophotometric data, as well as resolved Herschel images, to determine the dust spatial distribution in the inner exozodi and in the outer belt. We model in detail the two-component disk and the dust properties from the sub-AU scale to the outermost regions by fitting simultaneously all measurements against a large parameter space. The properties of the cold belt are consistent with a collisional cascade in a reservoir of ice-free planetesimals at 133 AU. It shows marginal evidence for asymmetries along the major axis. KIN enables us to establish that the warm dust consists of a ring that peaks between 0.2 and 0.8 AU. To reconcile this location with the ∼400 K dust temperature, very high albedo dust must be invoked, and a distribution of forsterite grains starting from micron sizes satisfies this criterion, while providing an excellent fit to the spectrum. We discuss additional constraints from the LBTI and near-infrared spectra, and we present predictions of what James Webb Space Telescope can unveil about this unusual object and whether it can detect unseen planets.

  7. Assessment of debris inputs from land into the river in the Three Gorges Reservoir Area, China.

    Science.gov (United States)

    Wan, Jing; Wang, Yonggui; Cheng, Meiling; Engel, Bernard A; Zhang, Wanshun; Peng, Hong

    2018-02-01

    Riverine debris in the Three Gorges Reservoir Area (TGRA) poses a threat to electricity generation, ship navigation, and water environment. Quantifying riverine debris inputs from land into the river is a foundation for modeling of the transport and accumulation of floating debris on the water surface in the TGRA. However, this has not been researched to date. In this study, debris inputs from land into the river in the TGRA were assessed according to the response relationship between debris inputs and surface runoff. The land-based debris inputs in the TGRA were estimated using simulated surface runoff which was simulated by the Soil and Water Assessment Tool (SWAT) model. Results showed that 15.32 × 10 6  kg of land-based debris was inputted into the main channel of the TGRA in 2015 which accounted for 9.74% of total debris inputs (the monitoring data of river-sourced and land-sourced debris inputs was 157.27 × 10 6  kg). Debris inputs varied seasonally and peaked in the summer season (July to September). Compared with monthly measured data, the average relative errors in 2015 were below 30%. In addition, areas with higher debris pollution inputs were mainly located in the upper section of the TGRA, between the Tang River Basin and the Long River Basin. The proposed method was tested and determined to be reliable; thus, it can be used to quickly estimate debris inputs from land into the river by surface runoff of the outlets in a river basin. Moreover, this method provides new insight into the estimation of land-based debris inputs into rivers.

  8. Uranium Dioxides and Debris Fragments Released to the Environment with Cesium-Rich Microparticles from the Fukushima Daiichi Nuclear Power Plant.

    Science.gov (United States)

    Ochiai, Asumi; Imoto, Junpei; Suetake, Mizuki; Komiya, Tatsuki; Furuki, Genki; Ikehara, Ryohei; Yamasaki, Shinya; Law, Gareth T W; Ohnuki, Toshihiko; Grambow, Bernd; Ewing, Rodney C; Utsunomiya, Satoshi

    2018-03-06

    Trace U was released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) during the meltdowns, but the speciation of the released components of the nuclear fuel remains unknown. We report, for the first time, the atomic-scale characteristics of nanofragments of the nuclear fuels that were released from the FDNPP into the environment. Nanofragments of an intrinsic U-phase were discovered to be closely associated with radioactive cesium-rich microparticles (CsMPs) in paddy soils collected ∼4 km from the FDNPP. The nanoscale fuel fragments were either encapsulated by or attached to CsMPs and occurred in two different forms: (i) UO 2+X nanocrystals of ∼70 nm size, which are embedded into magnetite associated with Tc and Mo on the surface and (ii) Isometric (U,Zr)O 2+X nanocrystals of ∼200 nm size, with the U/(U+Zr) molar ratio ranging from 0.14 to 0.91, with intrinsic pores (∼6 nm), indicating the entrapment of vapors or fission-product gases during crystallization. These results document the heterogeneous physical and chemical properties of debris at the nanoscale, which is a mixture of melted fuel and reactor materials, reflecting the complex thermal processes within the FDNPP reactor during meltdown. Still CsMPs are an important medium for the transport of debris fragments into the environment in a respirable form.

  9. Cabin Environment Physics Risk Model

    Science.gov (United States)

    Mattenberger, Christopher J.; Mathias, Donovan Leigh

    2014-01-01

    This paper presents a Cabin Environment Physics Risk (CEPR) model that predicts the time for an initial failure of Environmental Control and Life Support System (ECLSS) functionality to propagate into a hazardous environment and trigger a loss-of-crew (LOC) event. This physics-of failure model allows a probabilistic risk assessment of a crewed spacecraft to account for the cabin environment, which can serve as a buffer to protect the crew during an abort from orbit and ultimately enable a safe return. The results of the CEPR model replace the assumption that failure of the crew critical ECLSS functionality causes LOC instantly, and provide a more accurate representation of the spacecraft's risk posture. The instant-LOC assumption is shown to be excessively conservative and, moreover, can impact the relative risk drivers identified for the spacecraft. This, in turn, could lead the design team to allocate mass for equipment to reduce overly conservative risk estimates in a suboptimal configuration, which inherently increases the overall risk to the crew. For example, available mass could be poorly used to add redundant ECLSS components that have a negligible benefit but appear to make the vehicle safer due to poor assumptions about the propagation time of ECLSS failures.

  10. The application of numerical debris flow of modelling for the generation physical vulnerability curves

    NARCIS (Netherlands)

    Quan Luna, B.; Blahut, J.; Westen, C.J. van; Sterlacchini, C.J.S.; Asch, Th.W.J. van; Akbas, S.O.

    2011-01-01

    For a quantitative assessment of debris flow risk, it is essential to consider not only the hazardous process itself but also to perform an analysis of its consequences. This should include the estimation of the expected monetary losses as the product of the hazard with a given magnitude and

  11. Satellite Collision Modeling with Physics-Based Hydrocodes: Debris Generation Predictions of the Iridium-Cosmos Collision Event and Other Impact Events

    International Nuclear Information System (INIS)

    Springer, H.K.; Miller, W.O.; Levatin, J.L.; Pertica, A.J.; Olivier, S.S.

    2010-01-01

    Satellite collision debris poses risks to existing space assets and future space missions. Predictive models of debris generated from these hypervelocity collisions are critical for developing accurate space situational awareness tools and effective mitigation strategies. Hypervelocity collisions involve complex phenomenon that spans several time- and length-scales. We have developed a satellite collision debris modeling approach consisting of a Lagrangian hydrocode enriched with smooth particle hydrodynamics (SPH), advanced material failure models, detailed satellite mesh models, and massively parallel computers. These computational studies enable us to investigate the influence of satellite center-of-mass (CM) overlap and orientation, relative velocity, and material composition on the size, velocity, and material type distributions of collision debris. We have applied our debris modeling capability to the recent Iridium 33-Cosmos 2251 collision event. While the relative velocity was well understood in this event, the degree of satellite CM overlap and orientation was ill-defined. In our simulations, we varied the collision CM overlap and orientation of the satellites from nearly maximum overlap to partial overlap on the outermost extents of the satellites (i.e, solar panels and gravity boom). As expected, we found that with increased satellite overlap, the overall debris cloud mass and momentum (transfer) increases, the average debris size decreases, and the debris velocity increases. The largest predicted debris can also provide insight into which satellite components were further removed from the impact location. A significant fraction of the momentum transfer is imparted to the smallest debris (< 1-5mm, dependent on mesh resolution), especially in large CM overlap simulations. While the inclusion of the smallest debris is critical to enforcing mass and momentum conservation in hydrocode simulations, there seems to be relatively little interest in their

  12. Parameterization of a numerical 2-D debris flow model with entrainment: a case study of the Faucon catchment, Southern French Alps

    Directory of Open Access Journals (Sweden)

    H. Y. Hussin

    2012-10-01

    Full Text Available The occurrence of debris flows has been recorded for more than a century in the European Alps, accounting for the risk to settlements and other human infrastructure that have led to death, building damage and traffic disruptions. One of the difficulties in the quantitative hazard assessment of debris flows is estimating the run-out behavior, which includes the run-out distance and the related hazard intensities like the height and velocity of a debris flow. In addition, as observed in the French Alps, the process of entrainment of material during the run-out can be 10–50 times in volume with respect to the initially mobilized mass triggered at the source area. The entrainment process is evidently an important factor that can further determine the magnitude and intensity of debris flows. Research on numerical modeling of debris flow entrainment is still ongoing and involves some difficulties. This is partly due to our lack of knowledge of the actual process of the uptake and incorporation of material and due the effect of entrainment on the final behavior of a debris flow. Therefore, it is important to model the effects of this key erosional process on the formation of run-outs and related intensities. In this study we analyzed a debris flow with high entrainment rates that occurred in 2003 at the Faucon catchment in the Barcelonnette Basin (Southern French Alps. The historic event was back-analyzed using the Voellmy rheology and an entrainment model imbedded in the RAMMS 2-D numerical modeling software. A sensitivity analysis of the rheological and entrainment parameters was carried out and the effects of modeling with entrainment on the debris flow run-out, height and velocity were assessed.

  13. Remote Sensing of Plastic Debris

    Science.gov (United States)

    Garaba, S. P.; Dierssen, H. M.

    2016-02-01

    Plastic debris is becoming a nuisance in the environment and as a result there has been a dire need to synoptically detect and quantify them in the ocean and on land. We investigate the possible utility of spectral information determined from hand held, airborne and satellite remote sensing tools in the detection and identification polymer source of plastic debris. Sampled debris will be compared to our derived spectral library of typical raw polymer sources found at sea and in household waste. Additional work will be to determine ways to estimate the abundance of plastic debris in target areas. Implications of successful remote detection, tracking and quantification of plastic debris will be towards validating field observations over large areas and at repeated time intervals both on land and at sea.

  14. Experiments and simulation of a net closing mechanism for tether-net capture of space debris

    Science.gov (United States)

    Sharf, Inna; Thomsen, Benjamin; Botta, Eleonora M.; Misra, Arun K.

    2017-10-01

    This research addresses the design and testing of a debris containment system for use in a tether-net approach to space debris removal. The tether-net active debris removal involves the ejection of a net from a spacecraft by applying impulses to masses on the net, subsequent expansion of the net, the envelopment and capture of the debris target, and the de-orbiting of the debris via a tether to the chaser spacecraft. To ensure a debris removal mission's success, it is important that the debris be successfully captured and then, secured within the net. To this end, we present a concept for a net closing mechanism, which we believe will permit consistently successful debris capture via a simple and unobtrusive design. This net closing system functions by extending the main tether connecting the chaser spacecraft and the net vertex to the perimeter and around the perimeter of the net, allowing the tether to actuate closure of the net in a manner similar to a cinch cord. A particular embodiment of the design in a laboratory test-bed is described: the test-bed itself is comprised of a scaled-down tether-net, a supporting frame and a mock-up debris. Experiments conducted with the facility demonstrate the practicality of the net closing system. A model of the net closure concept has been integrated into the previously developed dynamics simulator of the chaser/tether-net/debris system. Simulations under tether tensioning conditions demonstrate the effectiveness of the closure concept for debris containment, in the gravity-free environment of space, for a realistic debris target. The on-ground experimental test-bed is also used to showcase its utility for validating the dynamics simulation of the net deployment, and a full-scale automated setup would make possible a range of validation studies of other aspects of a tether-net debris capture mission.

  15. Combining litter observations with a regional ocean model to identify sources and sinks of floating debris in a semi-enclosed basin: The Adriatic Sea

    DEFF Research Database (Denmark)

    Carlson, Daniel F.; Suaria, Giuseppe; Aliani, Stefano

    2017-01-01

    or to predict its fate, crucial information for management and mitigation policies. Particle tracking techniques have seen extensive use in these roles, however, most previous studies have used simplistic initial conditions based on bulk average inputs of debris to the system. Here, observations of floating...... anthropogenic macro debris in the Adriatic Sea are used to define initial conditions (number of particles, location, and time) in a Lagrangian particle tracking model. Particles are advected backward and forward in time for 60 days (120 days total) using surface velocities from an operational regional ocean...... model. Sources and sinks for debris observed in the central and southern Adriatic in May 2013 and March 2015 included the Italian coastline from Pescara to Brindisi, the Croatian island of Mljet, and the coastline from Dubrovnik through Montenegro to Albania. Debris observed in the northern Adriatic...

  16. APROS - A multifunctional modelling environment

    International Nuclear Information System (INIS)

    Juslin, K.; Paljakka, M.

    1999-01-01

    The Advanced Process Simulation (APROS) environment has after more than a decade of dedicated product development and intense commercial use reached a level of maturity that is difficult to find with regard to similar products. One of the basic ideas behind this software tool is its multifunctional concept. The concept requires that the tool is suitable for modelling and simulation of the dynamics of a process plant during all phases of its life-span from pre-design to training and model supported operation and control. The implementation of this concept had a significant impact on the software structure. Several, sometimes contradictory requirements had to be encompassed. It should be suitable both for small simple models and full scope simulators. It should facilitate time-steps from milliseconds to minutes, for the same models, just depending on the scope of study. It should combine several modelling paradigms such as continuous, discrete, mechanistic and empirical. The intrinsic model building blocks should be comprehensively verified, but users' model equations should be accepted, as well. It should be easy to connect to external models or hardware, and to use both in master or slave mode. It should be easy to study and modify the internals of the models, their structures and parameters, but it should also be possible to disclose all delicate model information from unwanted access. The calculation should be optimised for current computer hardware, but the model specifications should be easily transportable to new platforms. And finally, it should be suited both for researchers, engineers and plant operators. How did we succeed? We had 20 years of comprehensive thermal hydraulic modelling tradition before starting the project. We had the key experts with the key knowledge. We dedicated more than 100 man years of efforts for the new software developments. Presently, we have a superb team maintaining and improving the software, complemented with new enthusiastic

  17. Preservation of Late Amazonian Mars ice and water-related deposits in a unique crater environment in Noachis Terra: Age relationships between lobate debris tongues and gullies

    Science.gov (United States)

    Morgan, Gareth A.; Head, James W.; Marchant, David R.

    2011-01-01

    The Amazonian period of Mars has been described as static, cold, and dry. Recent analysis of high-resolution imagery of equatorial and mid-latitude regions has revealed an array of young landforms produced in association with ice and liquid water; because near-surface ice in these regions is currently unstable, these ice-and-water-related landforms suggest one or more episodes of martian climate change during the Amazonian. Here we report on the origin and evolution of valley systems within a degraded crater in Noachis Terra, Asimov Crater. The valleys have produced a unique environment in which to study the geomorphic signals of Amazonian climate change. New high-resolution images reveal Hesperian-aged layered basalt with distinctive columnar jointing capping interior crater fill and providing debris, via mass wasting, for the surrounding annular valleys. The occurrence of steep slopes (>20°), relatively narrow (sheltered) valleys, and a source of debris have provided favorable conditions for the preservation of shallow-ice deposits. Detailed mapping reveals morphological evidence for viscous ice flow, in the form of several lobate debris tongues (LDT). Superimposed on LDT are a series of fresh-appearing gullies, with typical alcove, channel, and fan morphologies. The shift from ice-rich viscous-flow formation to gully erosion is best explained as a shift in martian climate, from one compatible with excess snowfall and flow of ice-rich deposits, to one consistent with minor snow and gully formation. Available dating suggests that the climate transition occurred >8 Ma, prior to the formation of other small-scale ice-rich flow features identified elsewhere on Mars that have been interpreted to have formed during the most recent phases of high obliquity. Taken together, these older deposits suggest that multiple climatic shifts have occurred over the last tens of millions of years of martian history.

  18. Proposal for a model to assess the effect of seismic activity on the triggering of debris flows

    Science.gov (United States)

    Vidar Vangelsten, Bjørn; Liu, Zhongqiang; Eidsvig, Unni; Luna, Byron Quan; Nadim, Farrokh

    2013-04-01

    Landslide triggered by earthquakes is a serious threat for many communities around the world, and in some cases is known to have caused 25-50% of the earthquake fatalities. Seismic shaking can contribute to the triggering of debris flows either during the seismic event or indirectly by increasing the susceptibility of the slope to debris flow during intense rainfall in a period after the seismic event. The paper proposes a model to quantify both these effects. The model is based on an infinite slope formulation where precipitation and earthquakes influence the slope stability as follows: (1) During the shaking, the factor of safety is reduced due to cyclic pore pressure build-up where the cyclic pore pressure is modelled as a function of earthquake duration and intensity (measured as number of equivalent shear stress cycles and cyclic shear stress magnitude) and in-situ soil conditions (measured as average normalised shear stress). The model is calibrated using cyclic triaxial and direct simple shear (DSS) test data on clay and sand. (2) After the shaking, the factor of safety is modified using a combined empirical and analytical model that links observed earthquake induced changes in rainfall thresholds for triggering of debris flow to an equivalent reduction in soil shear strength. The empirical part uses data from past earthquakes to propose a conceptual model linking a site-specific reduction factor for rainfall intensity threshold (needed to trigger debris flows) to earthquake magnitude, distance from the epicentre and time period after the earthquake. The analytical part is a hydrological model for transient rainfall infiltration into an infinite slope in order to translate the change in rainfall intensity threshold into an equivalent reduction in soil shear strength. This is generalised into a functional form giving a site-specific shear strength reduction factor as function of earthquake history and soil conditions. The model is suitable for hazard and risk

  19. NASA Orbital Debris Large-Object Baseline Population in ORDEM 3.0

    Science.gov (United States)

    Krisco, Paula H.; Vavrin, A. B.; Anz-Meador, P. D.

    2013-01-01

    The NASA Orbital Debris Program Office (ODPO) has created and validated high fidelity populations of the debris environment for the latest Orbital Debris Engineering Model (ORDEM 3.0). Though the model includes fluxes of objects 10 um and larger, this paper considers particle fluxes for 1 cm and larger debris objects from low Earth orbit (LEO) through Geosynchronous Transfer Orbit (GTO). These are validated by several reliable radar observations through the Space Surveillance Network (SSN), Haystack, and HAX radars. ORDEM 3.0 populations were designed for the purpose of assisting, debris researchers and sensor developers in planning and testing. This environment includes a background derived from the LEO-to-GEO ENvironment Debris evolutionary model (LEGEND) with a Bayesian rescaling as well as specific events such as the FY-1C anti-satellite test, the Iridium 33/Cosmos 2251 accidental collision, and the Soviet/Russian Radar Ocean Reconnaissance Satellite (RORSAT) sodium-potassium droplet releases. The environment described in this paper is the most realistic orbital debris population larger than 1 cm, to date. We describe derivations of the background population and added specific populations. We present sample validation charts of our 1 cm and larger LEO population against Space Surveillance Network (SSN), Haystack, and HAX radar measurements.

  20. Application of the porous medium heat transfer model of ICARE/CATHARE code against debris bed and 'bundle' experiments

    International Nuclear Information System (INIS)

    Repetto, G.; Ederli, St.

    2007-01-01

    ICARE/CATHARE code is developed by the 'Institut de Radioprotection et de Surete Nucleaire' to simulate Nuclear Reactor behaviour during the course of a Loss of Cooling accident up to the core melting. The assessment of the heat transfer model in porous medium has been performed against experiments performed in ACRR (SNL-USA) and in Phebus reactors (at Cadarache - France). Calculation versus experiment results indicate a good agreement for the thermal behaviour. The heat transfers inside solid debris bed can be well predicted using the Imura-Yagi correlation to calculate the debris bed equivalent thermal conductivity in a wide range of particles size. In the case of 'Rod like geometry' calculations, the fuel rod assembly was modelled assuming several rings of fuel rods, with heat transfer including radiative phenomena using view factors between rods. An alternative modelling has been used considering the fuel rods as a porous medium with with pure UO 2 spherical particles of 1 cm diameter and a total porosity representative of the fuel bundle inside a cylindrical shroud. With this approach (heat exchanges accounted for with the Imura-Yagi correlation), the radial gradient calculated in a small bundle was significantly increased, from a few degrees (with the previous modelling) to about 150/200 K at 2273 K. This modelling has been recently improved, to account for the heat transfer inside a fuel rod bundle, by a specific model based on an electrical analogy, considering the porous medium as a cluster of true cylinders. (authors)

  1. Mapping distribution and thickness of supraglacial debris in the Central Karakoram National Park: main features and implications to model glacier meltwater

    Science.gov (United States)

    Minora, Umberto; Mayer, Christoph; Bocchiola, Daniele; D'Agata, Carlo; Maragno, Davide; Lambrecht, Astrid; Vuillermoz, Elisa; smiraglia, claudio; diolaiuti, guglielmina

    2014-05-01

    Supraglacial debris plays a not negligible role in controlling magnitude and rates of buried ice melt (Østrem, 1959; Mattson et al., 1993). Knowledge on rock debris is essential to model ice melt (and consequently meltwater discharge) upon wide glacierized areas, as melt rates are mainly driven by debris thickness variability. This is particularly important for the Pamir-Himalaya-Karakoram area (PHK), where debris-covered glaciers are frequent (Smiraglia et al., 2007; Scherler et al., 2011) and where melt water from glaciers supports agriculture and hydropower production. By means of remote sensing techniques and field data, supraglacial debris can be detected, and then quantified in area and thickness. Supervised classifications of satellite imagery can be used to map debris on glaciers. They use different algorithms to cluster an image based on its pixel values, and Region Of Interests (ROIs) previously selected by the human operator. This can be used to obtain a supraglacial debris mask by which surface extension can be calculated. Moreover, kinetic surface temperature data derived from satellites (such as ASTER and Landsat), can be used to quantify debris thicknesses (Mihalcea et al., 2008). Ground Control Points (GCPs) are essential to validate the obtained debris thicknesses. We took the Central Karakoram National Park (CKNP) as a representative sample for PHK area. The CKNP is 12,000 km2 wide, with more than 700 glaciers, mostly debris covered (Minora et al., 2013). Among those we find some of the widest glaciers of the World (e.g: Baltoro). To improve the knowledge on these glaciers and to better model their melt and water discharge we proceeded as follows. Firstly we ran a Supervised Maximum Likelihood (SML) classification on 2001 and 2010 Landsat images to detect debris presence and distribution. Secondly we analyzed kinetic surface temperature (from Landsat) to map debris depth. This latter attempt took also advantage from field data of debris thickness

  2. Marine debris occurrence and treatment: A review

    OpenAIRE

    Iñiguez, María Esperanza; Conesa, Juan A.; Fullana, Andres

    2016-01-01

    Marine debris produces a wide variety of negative environmental, economic, safety, health and cultural impacts. Most marine litter has a very low decomposition rate (as plastics, which are the most abundant type of marine debris), leading to a gradual, but significant accumulation in the coastal and marine environment. Along that time, marine debris is a significant source of chemical contaminants to the marine environment. Once extracted from the water, incineration is the method most widely...

  3. Space Debris & its Mitigation

    Science.gov (United States)

    Kaushal, Sourabh; Arora, Nishant

    2012-07-01

    Space debris has become a growing concern in recent years, since collisions at orbital velocities can be highly damaging to functioning satellites and can also produce even more space debris in the process. Some spacecraft, like the International Space Station, are now armored to deal with this hazard but armor and mitigation measures can be prohibitively costly when trying to protect satellites or human spaceflight vehicles like the shuttle. This paper describes the current orbital debris environment, outline its main sources, and identify mitigation measures to reduce orbital debris growth by controlling these sources. We studied the literature on the topic Space Debris. We have proposed some methods to solve this problem of space debris. We have also highlighted the shortcomings of already proposed methods by space experts and we have proposed some modification in those methods. Some of them can be very effective in the process of mitigation of space debris, but some of them need some modification. Recently proposed methods by space experts are maneuver, shielding of space elevator with the foil, vaporizing or redirecting of space debris back to earth with the help of laser, use of aerogel as a protective layer, construction of large junkyards around international space station, use of electrodynamics tether & the latest method proposed is the use of nano satellites in the clearing of the space debris. Limitations of the already proposed methods are as follows: - Maneuvering can't be the final solution to our problem as it is the act of self-defence. - Shielding can't be done on the parts like solar panels and optical devices. - Vaporizing or redirecting of space debris can affect the human life on earth if it is not done in proper manner. - Aerogel has a threshold limit up to which it can bear (resist) the impact of collision. - Large junkyards can be effective only for large sized debris. In this paper we propose: A. The Use of Nano Tubes by creating a mesh

  4. Tornado Damage Assessment: Reconstructing the Wind Through Debris Tracking and Treefall Pattern Analysis

    Science.gov (United States)

    Godfrey, C. M.; Peterson, C. J.; Lombardo, F.

    2017-12-01

    Efforts to enhance the resilience of communities to tornadoes requires an understanding of the interconnected nature of debris and damage propagation in both the built and natural environment. A first step toward characterizing the interconnectedness of these elements within a given community involves detailed post-event surveys of tornado damage. Such damage surveys immediately followed the 22 January 2017 EF3 tornadoes in the southern Georgia towns of Nashville and Albany. After assigning EF-scale ratings to impacted structures, the authors geotagged hundreds of pieces of debris scattered around selected residential structures and outbuildings in each neighborhood and paired each piece of debris with its source structure. Detailed information on trees in the vicinity of the structures supplements the debris data, including the species, dimensions, location, fall direction, and level of damage. High-resolution satellite imagery helps to identify the location and fall direction of hundreds of additional forest trees. These debris and treefall patterns allow an estimation of the near-surface wind field using a Rankine vortex model coupled with both a tree stability model and an infrastructure fragility model that simulates debris flight. Comparisons between the modeled damage and the actual treefall and debris field show remarkable similarities for a selected set of vortex parameters, indicating the viability of this approach for estimating enhanced Fujita scale levels, determining the near-surface wind field of a tornado during its passage through a neighborhood, and identifying how debris may contribute to the overall risk from tornadoes.

  5. A Comparison of the SOCIT and DebriSat Experiments

    Science.gov (United States)

    Ausay, Erick; Blake, Brandon; Boyle, Colleen; Cornejo, Alex; Horn, Alexa; Palma, Kirsten; Pistella, Frank; Sato, Taishi; Todd, Naromi; Zimmerman, Jeffrey; hide

    2017-01-01

    This paper explores the differences between, and shares the lessons learned from, two hypervelocity impact experiments critical to the update of orbital debris environment models. The procedures and processes of the fourth Satellite Orbital Debris Characterization Impact Test (SOCIT) were analyzed and related to the ongoing DebriSat experiment. SOCIT was the first hypervelocity impact test designed specifically for satellites in Low Earth Orbit (LEO). It targeted a 1960's U.S. Navy satellite, from which data was obtained to update pre-existing NASA and DOD breakup models. DebriSat is a comprehensive update to these satellite breakup models- necessary since the material composition and design of satellites have evolved from the time of SOCIT. Specifically, DebriSat utilized carbon fiber, a composite not commonly used in satellites during the construction of the US Navy Transit satellite used in SOCIT. Although DebriSat is an ongoing activity, multiple points of difference are drawn between the two projects. Significantly, the hypervelocity tests were conducted with two distinct satellite models and test configurations, including projectile and chamber layout. While both hypervelocity tests utilized soft catch systems to minimize fragment damage to its post-impact shape, SOCIT only covered 65% of the projected area surrounding the satellite, whereas, DebriSat was completely surrounded cross-range and downrange by the foam panels to more completely collect fragments. Furthermore, utilizing lessons learned from SOCIT, DebriSat's post-impact processing varies in methodology (i.e., fragment collection, measurement, and characterization). For example, fragment sizes were manually determined during the SOCIT experiment, while DebriSat utilizes automated imaging systems for measuring fragments, maximizing repeatability while minimizing the potential for human error. In addition to exploring these variations in methodologies and processes, this paper also presents the

  6. Mathematical modelling of the transport of a poorly sorted granular mixture as a debris-flow. The case of Madeira Island torrential floods in 2010

    Science.gov (United States)

    Ferreira, Rui M. L.; Oliveira, Rodrigo P.; Conde, Daniel

    2016-04-01

    On the 20th February 2010, heavy rainfall was registered at Madeira Island, North Atlantic. Stony debris flows, mudflows and mudslides ensued causing severe property loss, 1.5 m thick sediment deposits at downtown Funchal including 16th century monuments, and a death toll of 47 lives. Debris-flow fronts propagated downstream while carrying very high concentrations of solid material. These two-phase solid-fluid flows were responsible for most of the infrastructural damage across the island, due to their significantly increased mass and momentum. The objective of the present modelling work is to validate a 2DH model for torrential flows featuring the transport and interaction of several size fractions of a poorly-sorted granular mixture typical of stony debris flow in Madeira. The module for the transport of poorly-sorted material was included in STAV-2D (CERIS-IST), a shallow-water and morphology solver based on a finite-volume method using a flux-splitting technique featuring a reviewed Roe-Riemann solver, with appropriate source-term formulations to ensure full conservativeness. STAV-2D also includes formulations of flow resistance and bedload transport adequate for debris-flows with natural mobile beds (Ferreira et al., 2009) and has been validated with both theoretical solutions and laboratory data (Soares-Frazão et al., 2012; Canelas et al., 2013). The modelling of the existing natural and built environment is fully explicit. All buildings, streets and channels are accurately represented within the mesh geometry. Such detail is relevant for the reliability of the validation using field data, since the major sedimentary deposits within the urban meshwork of Funchal were identified and characterized in terms of volume and grain size distribution during the aftermath of the 20th February of 2010 event. Indeed, the measure of the quality of the numerical results is the agreement between simulated and estimated volume of deposited sediment and between estimated and

  7. To eat or not to eat? Debris selectivity by marine turtles.

    Science.gov (United States)

    Schuyler, Qamar; Hardesty, Britta Denise; Wilcox, Chris; Townsend, Kathy

    2012-01-01

    Marine debris is a growing problem for wildlife, and has been documented to affect more than 267 species worldwide. We investigated the prevalence of marine debris ingestion in 115 sea turtles stranded in Queensland between 2006-2011, and assessed how the ingestion rates differ between species (Eretmochelys imbricata vs. Chelonia mydas) and by turtle size class (smaller oceanic feeders vs. larger benthic feeders). Concurrently, we conducted 25 beach surveys to estimate the composition of the debris present in the marine environment. Based on this proxy measurement of debris availability, we modeled turtles' debris preferences (color and type) using a resource selection function, a method traditionally used for habitat and food selection. We found no significant difference in the overall probability of ingesting debris between the two species studied, both of which have similar life histories. Curved carapace length, however, was inversely correlated with the probability of ingesting debris; 54.5% of pelagic sized turtles had ingested debris, whereas only 25% of benthic feeding turtles were found with debris in their gastrointestinal system. Benthic and pelagic sized turtles also exhibited different selectivity ratios for debris ingestion. Benthic phase turtles had a strong selectivity for soft, clear plastic, lending support to the hypothesis that sea turtles ingest debris because it resembles natural prey items such as jellyfish. Pelagic turtles were much less selective in their feeding, though they showed a trend towards selectivity for rubber items such as balloons. Most ingested items were plastic and were positively buoyant. This study highlights the need to address increasing amounts of plastic in the marine environment, and provides evidence for the disproportionate ingestion of balloons by marine turtles.

  8. To Eat or Not to Eat? Debris Selectivity by Marine Turtles

    Science.gov (United States)

    Schuyler, Qamar; Hardesty, Britta Denise; Wilcox, Chris; Townsend, Kathy

    2012-01-01

    Marine debris is a growing problem for wildlife, and has been documented to affect more than 267 species worldwide. We investigated the prevalence of marine debris ingestion in 115 sea turtles stranded in Queensland between 2006–2011, and assessed how the ingestion rates differ between species (Eretmochelys imbricata vs. Chelonia mydas) and by turtle size class (smaller oceanic feeders vs. larger benthic feeders). Concurrently, we conducted 25 beach surveys to estimate the composition of the debris present in the marine environment. Based on this proxy measurement of debris availability, we modeled turtles’ debris preferences (color and type) using a resource selection function, a method traditionally used for habitat and food selection. We found no significant difference in the overall probability of ingesting debris between the two species studied, both of which have similar life histories. Curved carapace length, however, was inversely correlated with the probability of ingesting debris; 54.5% of pelagic sized turtles had ingested debris, whereas only 25% of benthic feeding turtles were found with debris in their gastrointestinal system. Benthic and pelagic sized turtles also exhibited different selectivity ratios for debris ingestion. Benthic phase turtles had a strong selectivity for soft, clear plastic, lending support to the hypothesis that sea turtles ingest debris because it resembles natural prey items such as jellyfish. Pelagic turtles were much less selective in their feeding, though they showed a trend towards selectivity for rubber items such as balloons. Most ingested items were plastic and were positively buoyant. This study highlights the need to address increasing amounts of plastic in the marine environment, and provides evidence for the disproportionate ingestion of balloons by marine turtles. PMID:22829894

  9. To eat or not to eat? Debris selectivity by marine turtles.

    Directory of Open Access Journals (Sweden)

    Qamar Schuyler

    Full Text Available Marine debris is a growing problem for wildlife, and has been documented to affect more than 267 species worldwide. We investigated the prevalence of marine debris ingestion in 115 sea turtles stranded in Queensland between 2006-2011, and assessed how the ingestion rates differ between species (Eretmochelys imbricata vs. Chelonia mydas and by turtle size class (smaller oceanic feeders vs. larger benthic feeders. Concurrently, we conducted 25 beach surveys to estimate the composition of the debris present in the marine environment. Based on this proxy measurement of debris availability, we modeled turtles' debris preferences (color and type using a resource selection function, a method traditionally used for habitat and food selection. We found no significant difference in the overall probability of ingesting debris between the two species studied, both of which have similar life histories. Curved carapace length, however, was inversely correlated with the probability of ingesting debris; 54.5% of pelagic sized turtles had ingested debris, whereas only 25% of benthic feeding turtles were found with debris in their gastrointestinal system. Benthic and pelagic sized turtles also exhibited different selectivity ratios for debris ingestion. Benthic phase turtles had a strong selectivity for soft, clear plastic, lending support to the hypothesis that sea turtles ingest debris because it resembles natural prey items such as jellyfish. Pelagic turtles were much less selective in their feeding, though they showed a trend towards selectivity for rubber items such as balloons. Most ingested items were plastic and were positively buoyant. This study highlights the need to address increasing amounts of plastic in the marine environment, and provides evidence for the disproportionate ingestion of balloons by marine turtles.

  10. Active Space Debris Removal System

    Directory of Open Access Journals (Sweden)

    Gabriele GUERRA

    2017-06-01

    Full Text Available Since the start of the space era, more than 5000 launches have been carried out, each carrying satellites for many disparate uses, such as Earth observation or communication. Thus, the space environment has become congested and the problem of space debris is now generating some concerns in the space community due to our long-lived belief that “space is big”. In the last few years, solutions to this problem have been proposed, one of those is Active Space Debris Removal: this method will reduce the increasing debris growth and permit future sustainable space activities. The main idea of the method proposed below is a drag augmentation system: use a system capable of putting an expanded foam on a debris which will increase the area-to-mass ratio to increase the natural atmospheric drag and solar pressure. The drag augmentation system proposed here requires a docking system; the debris will be pushed to its release height and then, after un-docking, an uncontrolled re-entry takes place ending with a burn up of the object and the foam in the atmosphere within a given time frame. The method requires an efficient way to change the orbit between two debris. The present paper analyses such a system in combination with an Electric Propulsion system, and emphasizes the choice of using two satellites to remove five effective rockets bodies debris within a year.

  11. Spacecraft Internal Acoustic Environment Modeling

    Science.gov (United States)

    Chu, SShao-sheng R.; Allen, Christopher S.

    2009-01-01

    carried out by acquiring octave band microphone data simultaneously at ten fixed locations throughout the mockup. SPLs (Sound Pressure Levels) predicted by our SEA model match well with measurements for our CM mockup, with a more complicated shape. Additionally in FY09, background NC noise (Noise Criterion) simulation and MRT (Modified Rhyme Test) were developed and performed in the mockup to determine the maximum noise level in CM habitable volume for fair crew voice communications. Numerous demonstrations of simulated noise environment in the mockup and associated SIL (Speech Interference Level) via MRT were performed for various communities, including members from NASA and Orion prime-/sub-contractors. Also, a new HSIR (Human-Systems Integration Requirement) for limiting pre- and post-landing SIL was proposed.

  12. A data-driven approach for modeling post-fire debris-flow volumes and their uncertainty

    Science.gov (United States)

    Friedel, Michael J.

    2011-01-01

    This study demonstrates the novel application of genetic programming to evolve nonlinear post-fire debris-flow volume equations from variables associated with a data-driven conceptual model of the western United States. The search space is constrained using a multi-component objective function that simultaneously minimizes root-mean squared and unit errors for the evolution of fittest equations. An optimization technique is then used to estimate the limits of nonlinear prediction uncertainty associated with the debris-flow equations. In contrast to a published multiple linear regression three-variable equation, linking basin area with slopes greater or equal to 30 percent, burn severity characterized as area burned moderate plus high, and total storm rainfall, the data-driven approach discovers many nonlinear and several dimensionally consistent equations that are unbiased and have less prediction uncertainty. Of the nonlinear equations, the best performance (lowest prediction uncertainty) is achieved when using three variables: average basin slope, total burned area, and total storm rainfall. Further reduction in uncertainty is possible for the nonlinear equations when dimensional consistency is not a priority and by subsequently applying a gradient solver to the fittest solutions. The data-driven modeling approach can be applied to nonlinear multivariate problems in all fields of study.

  13. Experimental validation of damping properties and solar pressure effects on flexible, high area-to-mass ratio debris model

    Science.gov (United States)

    Channumsin, Sittiporn; Ceriotti, Matteo; Radice, Gianmarco; Watson, Ian

    2017-09-01

    Multilayer insulation (MLI) is a recently-discovered type of debris originating from delamination of aging spacecraft; it is mostly detected near the geosynchronous orbit (GEO). Observation data indicates that these objects are characterised by high reflectivity, high area-to-mass ratio (HAMR), fast rotation, high sensitivity to perturbations (especially solar radiation pressure) and change of area-to-mass ratio (AMR) over time. As a result, traditional models (e.g. cannonball) are unsuitable to represent and predict this debris' orbital evolution. Previous work by the authors effectively modelled the flexible debris by means of multibody dynamics to improve the prediction accuracy. The orbit evolution with the flexible model resulted significantly different from using the rigid model. This paper aims to present a methodology to determine the dynamic properties of thin membranes with the purpose to validate the deformation characteristics of the flexible model. A high-vacuum chamber (10-4 mbar) to significantly decrease air friction, inside which a thin membrane is hinged at one end but free at the other provides the experimental setup. A free motion test is used to determine the damping characteristics and natural frequency of the thin membrane via logarithmic decrement and frequency response. The membrane can swing freely in the chamber and the motion is tracked by a static, optical camera, and a Kalman filter technique is implemented in the tracking algorithm to reduce noise and increase the tracking accuracy of the oscillating motion. Then, the effect of solar radiation pressure on the thin membrane is investigated: a high power spotlight (500-2000 W) is used to illuminate the sample and any displacement of the membrane is measured by means of a high-resolution laser sensor. Analytic methods from the natural frequency response and Finite Element Analysis (FEA) including multibody simulations of both experimental setups are used for the validation of the

  14. A three dimensional two-phase debris flow model: Reduction to one free model parameter by linking rheology to grain size distribution and water content

    Science.gov (United States)

    von Boetticher, Albrecht; McArdell, Brian; Rickenmann, Dieter; Hübl, Johannes; Scheidl, Christian

    2014-05-01

    Attempts to model debris flow material either as a granular or as a viscous matter can not account for the wide range of debris flow processes, leading to the development of two-phase models with one phase accounting for the fluid and the other for the grains. Within this group of models, depth-averaged approaches are wide-spread, but since the rheology of true material is sensitive to pressure and shear gradient, three dimensional simulations are necessary to predict flows in complex geometries. Phase interaction can be modelled by solving the Navier-Stokes equation system for each phase and linking the phases with drag force models. However, this is a numerically expensive way that introduces a number of free parameters because too little is known about drag of non-spherical grains in non-Newtonian fluids. The approach proposed here solves one phase-averaged Navier-stokes equation system by applying the Volume of Fluid method, while still allowing to account for the sensitivity of the local rheology to pressure and shear in dependency to phase concentrations. One phase with a Herschel-Bulkley rheology represents the interstitial fluid and can mix with a second phase with the Coulomb-viscoplastic rheology of Pudasaini (Birte et al. 2013) that represents the gravel. A third phase is kept separate and represents the air. This setup allows modelling key properties of debris flow processes like run out or impact in high detail. By linking the Herschel Bulkley parameters to water content, clay mineral proportion and grain size distribution (Kaitna et al. 2007, Yu et al. 2013), and the parameters of the Coulomb-viscoplastic rheology to the angle of repose of the gravel, a reduction to one free model parameter was achieved. The resulting model is tested with laboratory experiments for its capability to reproduce the sensitivity of debris flow material to water content and channel curvature. Existing large scale flume experiments are used to corroborate the model and

  15. A COMPREHENSIVE DUST MODEL APPLIED TO THE RESOLVED BETA PICTORIS DEBRIS DISK FROM OPTICAL TO RADIO WAVELENGTHS

    Energy Technology Data Exchange (ETDEWEB)

    Ballering, Nicholas P.; Su, Kate Y. L.; Rieke, George H.; Gáspár, András, E-mail: ballerin@email.arizona.edu [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

    2016-06-01

    We investigate whether varying the dust composition (described by the optical constants) can solve a persistent problem in debris disk modeling—the inability to fit the thermal emission without overpredicting the scattered light. We model five images of the β Pictoris disk: two in scattered light from the Hubble Space Telescope ( HST )/Space Telescope Imaging Spectrograph at 0.58 μ m and HST /Wide Field Camera 3 (WFC 3) at 1.16 μ m, and three in thermal emission from Spitzer /Multiband Imaging Photometer for Spitzer (MIPS) at 24 μ m, Herschel /PACS at 70 μ m, and Atacama Large Millimeter/submillimeter Array at 870 μ m. The WFC3 and MIPS data are published here for the first time. We focus our modeling on the outer part of this disk, consisting of a parent body ring and a halo of small grains. First, we confirm that a model using astronomical silicates cannot simultaneously fit the thermal and scattered light data. Next, we use a simple generic function for the optical constants to show that varying the dust composition can improve the fit substantially. Finally, we model the dust as a mixture of the most plausible debris constituents: astronomical silicates, water ice, organic refractory material, and vacuum. We achieve a good fit to all data sets with grains composed predominantly of silicates and organics, while ice and vacuum are, at most, present in small amounts. This composition is similar to one derived from previous work on the HR 4796A disk. Our model also fits the thermal spectral energy distribution, scattered light colors, and high-resolution mid-IR data from T-ReCS for this disk. Additionally, we show that sub-blowout grains are a necessary component of the halo.

  16. Applying an energy balance model of a debris covered glacier through the Himalayan seasons - insights from the field and sensitivity analysis

    Science.gov (United States)

    Steiner, Jakob; Pellicciotti, Francesca; Buri, Pascal; Brock, Ben

    2016-04-01

    Although some recent studies have attempted to model melt below debris cover in the Himalaya as well as the European Alps, field measurements remain rare and uncertainties of a number of parameters are difficult to constrain. The difficulty of accurately measuring sub-debris melt at one location over a longer period of time with stakes adds to the challenge of calibrating models adequately, as moving debris tends to tilt stakes. Based on measurements of sub-debris melt with stakes as well as air and surface temperature at the same location during three years from 2012 to 2014 at Lirung Glacier in the Nepalese Himalaya, we investigate results with the help of an earlier developed energy balance model. We compare stake readings to cumulative melt as well as observed to modelled surface temperatures. With timeseries stretching through the pre-Monsoon, Monsoon and post-Monsoon of different years we can show the difference of sensitive parameters during these seasons. Using radiation measurements from the AWS we can use a temporarily variable time series of albedo. A thorough analysis of thermistor data showing the stratigraphy of the temperature through the debris layer allows a detailed discussion of the variability as well as the uncertainty range of thermal conductivity. Distributed wind data as well as results from a distributed surface roughness assessment allows to constrain variability of turbulent fluxes between the different locations of the stakes. We show that model results are especially sensitive to thermal conductivity, a value that changes substantially between the seasons. Values obtained from the field are compared to earlier studies, which shows large differences within locations in the Himalaya. We also show that wind varies with more than a factor two between depressions and on debris mounds which has a significant influence on turbulent fluxes. Albedo decreases from the dry to the wet season and likely has some spatial variability that is

  17. Progress toward the determination of correct classification rates in fire debris analysis II: utilizing soft independent modeling of class analogy (SIMCA).

    Science.gov (United States)

    Waddell, Erin E; Williams, Mary R; Sigman, Michael E

    2014-07-01

    A multistep classification scheme was used to detect and classify ignitable liquid residues in fire debris into the classes defined by the ASTM E1618-10 standard method. The total ion spectra (TIS) of the samples were classified by soft independent modeling of class analogy (SIMCA) with cross-validation and tested on fire debris. For detection of ignitable liquid residue, the true-positive rate was 94.2% for cross-validation and 79.1% for fire debris, with false-positive rates of 5.1% and 8.9%, respectively. Evaluation of SIMCA classifications for fire debris relative to a reviewer's examination led to an increase in the true-positive rate to 95.1%; however, the false-positive rate also increased to 15.0%. The correct classification rates for assigning ignitable liquid residues into ASTM E1618-10 classes were generally in the range of 80-90%, with the exception of gasoline samples, which were incorrectly classified as aromatic solvents following evaporative weathering in fire debris. © 2014 American Academy of Forensic Sciences.

  18. Engineering and Technology Challenges for Active Debris Removal

    Science.gov (United States)

    Liou, Jer-Chyi

    2011-01-01

    After more than fifty years of space activities, the near-Earth environment is polluted with man-made orbital debris. The collision between Cosmos 2251 and the operational Iridium 33 in 2009 signaled a potential collision cascade effect, also known as the "Kessler Syndrome", in the environment. Various modelling studies have suggested that the commonly-adopted mitigation measures will not be sufficient to stabilize the future debris population. Active debris removal must be considered to remediate the environment. This paper summarizes the key issues associated with debris removal and describes the technology and engineering challenges to move forward. Fifty-four years after the launch of Sputnik 1, satellites have become an integral part of human society. Unfortunately, the ongoing space activities have left behind an undesirable byproduct orbital debris. This environment problem is threatening the current and future space activities. On average, two Shuttle window panels are replaced after every mission due to damage by micrometeoroid or orbital debris impacts. More than 100 collision avoidance maneuvers were conducted by satellite operators in 2010 to reduce the impact risks of their satellites with respect to objects in the U.S. Space Surveillance Network (SSN) catalog. Of the four known accident collisions between objects in the SSN catalog, the last one, collision between Cosmos 2251 and the operational Iridium 33 in 2009, was the most significant. It was the first ever accidental catastrophic destruction of an operational satellite by another satellite. It also signaled the potential collision cascade effect in the environment, commonly known as the "Kessler Syndrome," predicted by Kessler and Cour-Palais in 1978 [1]. Figure 1 shows the historical increase of objects in the SSN catalog. The majority of the catalog objects are 10 cm and larger. As of April 2011, the total objects tracked by the SSN sensors were more than 22,000. However, approximately 6000 of

  19. A SELF-CONSISTENT MODEL OF THE CIRCUMSTELLAR DEBRIS CREATED BY A GIANT HYPERVELOCITY IMPACT IN THE HD 172555 SYSTEM

    International Nuclear Information System (INIS)

    Spectral modeling of the large infrared excess in the Spitzer IRS spectra of HD 172555 suggests that there is more than 10 19 kg of submicron dust in the system. Using physical arguments and constraints from observations, we rule out the possibility of the infrared excess being created by a magma ocean planet or a circumplanetary disk or torus. We show that the infrared excess is consistent with a circumstellar debris disk or torus, located at ∼6 AU, that was created by a planetary scale hypervelocity impact. We find that radiation pressure should remove submicron dust from the debris disk in less than one year. However, the system's mid-infrared photometric flux, dominated by submicron grains, has been stable within 4% over the last 27 years, from the Infrared Astronomical Satellite (1983) to WISE (2010). Our new spectral modeling work and calculations of the radiation pressure on fine dust in HD 172555 provide a self-consistent explanation for this apparent contradiction. We also explore the unconfirmed claim that ∼10 47 molecules of SiO vapor are needed to explain an emission feature at ∼8 μm in the Spitzer IRS spectrum of HD 172555. We find that unless there are ∼10 48 atoms or 0.05 M ⊕ of atomic Si and O vapor in the system, SiO vapor should be destroyed by photo-dissociation in less than 0.2 years. We argue that a second plausible explanation for the ∼8 μm feature can be emission from solid SiO, which naturally occurs in submicron silicate ''smokes'' created by quickly condensing vaporized silicate.

  20. A SELF-CONSISTENT MODEL OF THE CIRCUMSTELLAR DEBRIS CREATED BY A GIANT HYPERVELOCITY IMPACT IN THE HD 172555 SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, B. C.; Melosh, H. J. [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States); Lisse, C. M. [JHU-APL, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Chen, C. H. [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Wyatt, M. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Thebault, P. [LESIA, Observatoire de Paris, F-92195 Meudon Principal Cedex (France); Henning, W. G. [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Gaidos, E. [Department of Geology and Geophysics, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Elkins-Tanton, L. T. [Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC 20015 (United States); Bridges, J. C. [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Morlok, A., E-mail: johns477@purdue.edu [Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

    2012-12-10

    Spectral modeling of the large infrared excess in the Spitzer IRS spectra of HD 172555 suggests that there is more than 10{sup 19} kg of submicron dust in the system. Using physical arguments and constraints from observations, we rule out the possibility of the infrared excess being created by a magma ocean planet or a circumplanetary disk or torus. We show that the infrared excess is consistent with a circumstellar debris disk or torus, located at {approx}6 AU, that was created by a planetary scale hypervelocity impact. We find that radiation pressure should remove submicron dust from the debris disk in less than one year. However, the system's mid-infrared photometric flux, dominated by submicron grains, has been stable within 4% over the last 27 years, from the Infrared Astronomical Satellite (1983) to WISE (2010). Our new spectral modeling work and calculations of the radiation pressure on fine dust in HD 172555 provide a self-consistent explanation for this apparent contradiction. We also explore the unconfirmed claim that {approx}10{sup 47} molecules of SiO vapor are needed to explain an emission feature at {approx}8 {mu}m in the Spitzer IRS spectrum of HD 172555. We find that unless there are {approx}10{sup 48} atoms or 0.05 M{sub Circled-Plus} of atomic Si and O vapor in the system, SiO vapor should be destroyed by photo-dissociation in less than 0.2 years. We argue that a second plausible explanation for the {approx}8 {mu}m feature can be emission from solid SiO, which naturally occurs in submicron silicate ''smokes'' created by quickly condensing vaporized silicate.

  1. The impact of debris on marine life.

    Science.gov (United States)

    Gall, S C; Thompson, R C

    2015-03-15

    Marine debris is listed among the major perceived threats to biodiversity, and is cause for particular concern due to its abundance, durability and persistence in the marine environment. An extensive literature search reviewed the current state of knowledge on the effects of marine debris on marine organisms. 340 original publications reported encounters between organisms and marine debris and 693 species. Plastic debris accounted for 92% of encounters between debris and individuals. Numerous direct and indirect consequences were recorded, with the potential for sublethal effects of ingestion an area of considerable uncertainty and concern. Comparison to the IUCN Red List highlighted that at least 17% of species affected by entanglement and ingestion were listed as threatened or near threatened. Hence where marine debris combines with other anthropogenic stressors it may affect populations, trophic interactions and assemblages. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Persistent marine debris

    International Nuclear Information System (INIS)

    Levy, E.M.

    1992-01-01

    In this paper the distribution of persistent marine debris, adrift on world oceans and stranded on beaches globally, is reviewed and related to the known inputs and transport by the major surface currents. Since naturally occurring processes eventually degrade petroleum in the environment, international measures to reduce the inputs have been largely successful in alleviating oil pollution on a global, if not on a local, scale. Many plastics, however, are so resistant to natural degradation that merely controlling inputs will be insufficient, and more drastic and costly measures will be needed to cope with the emerging global problem posed by these materials

  3. Holonic Modelling of Large Scale Geographic Environments

    Science.gov (United States)

    Mekni, Mehdi; Moulin, Bernard

    In this paper, we propose a novel approach to model Virtual Geographic Environments (VGE) which uses the holonic approach as a computational geographic methodology and holarchy as organizational principle. Our approach allows to automatically build VGE using data provided by Geographic Information Systems (GIS) and enables an explicit representation of the geographic environment for Situated Multi-Agent Systems (SMAS) in which agents are situated and with which they interact. In order to take into account geometric, topologic, and semantic characteristics of the geographic environment, we propose the use of the holonic approach to build the environment holarchy. We illustrate our holonic model using two different environments: an urban environment and a natural environment.

  4. The Martian Energetic Radiation Environment Models

    Science.gov (United States)

    Gonçalves, Patrícia; Keating, Ana; Truscott, Pete; Lei, Fan; Desorgher, Laurent; Heynderickx, Daniel; Crosby, Norma Bock; Nieminen, Petteri; Santin, Giovanni

    The Martian Energetic Radiation Environment Models The high energy ionising radiation environment in the solar system consists of three main sources: the planetary radiation belts, galactic cosmic rays and solar energetic particles. Future Mars missions potentially carry significant risk from long-term exposure to ionising radiation. The Martian Energetic Radiation Environment Models, MEREM, were developed in order to simulate the Martian radiation environment. The models, eMEREM and dMEREM, respec-tively engineering and detailed Martian Energetic Radiation Environment Models, are based on the Geant4 and FLUKA radiation transport programs, combined with Mars Climate Database model for the atmosphere. MOLA (Mars Orbiter Laser Altimeter) data and gamma-ray spec-trometer data have been used to define surface topology and surface composition (including presence of water), respectively. Although the models are capable of operating on standalone mode, a SPENVIS (space envi-ronment information system) compatible, web-based user interface was developed to provide an integrated environment to predict the Martian radiation and greatly simplify the operation of the software by non-experts and by future mission developers. Results of the Mars Energetic Radiation Environment Models concerning the estimate of effec-tive doses and ambient dose equivalents for potential Martian landing sites having regard to the combined incidence, under solar minimum and solar maximum conditions, of flare related particle radiation and background galactic cosmic ray radiation are presented.

  5. Statistical Estimation of Orbital Debris Populations with a Spectrum of Object Size

    Science.gov (United States)

    Xu, Y. -l; Horstman, M.; Krisko, P. H.; Liou, J. -C; Matney, M.; Stansbery, E. G.; Stokely, C. L.; Whitlock, D.

    2008-01-01

    Orbital debris is a real concern for the safe operations of satellites. In general, the hazard of debris impact is a function of the size and spatial distributions of the debris populations. To describe and characterize the debris environment as reliably as possible, the current NASA Orbital Debris Engineering Model (ORDEM2000) is being upgraded to a new version based on new and better quality data. The data-driven ORDEM model covers a wide range of object sizes from 10 microns to greater than 1 meter. This paper reviews the statistical process for the estimation of the debris populations in the new ORDEM upgrade, and discusses the representation of large-size (greater than or equal to 1 m and greater than or equal to 10 cm) populations by SSN catalog objects and the validation of the statistical approach. Also, it presents results for the populations with sizes of greater than or equal to 3.3 cm, greater than or equal to 1 cm, greater than or equal to 100 micrometers, and greater than or equal to 10 micrometers. The orbital debris populations used in the new version of ORDEM are inferred from data based upon appropriate reference (or benchmark) populations instead of the binning of the multi-dimensional orbital-element space. This paper describes all of the major steps used in the population-inference procedure for each size-range. Detailed discussions on data analysis, parameter definition, the correlation between parameters and data, and uncertainty assessment are included.

  6. Computer-Based Modeling Environments

    Science.gov (United States)

    1989-01-01

    1988). "An introduction to graph-based modeling Rich. E. (1983). Artificial Inteligence , McGraw-Hill, New York. systems", Working Paper 88-10-2...Hall, J., S. Lippman, and J. McCall. "Expected Utility Maximizing Job Search," Chapter 7 of Studies in the Economics of Search, 1979, North-Holland. WMSI...The same shape has been used theory, as knowledge representation in artificial for data sources and analytical models because, at intelligence, and as

  7. Global analysis of anthropogenic debris ingestion by sea turtles.

    Science.gov (United States)

    Schuyler, Qamar; Hardesty, Britta Denise; Wilcox, Chris; Townsend, Kathy

    2014-02-01

    Ingestion of marine debris can have lethal and sublethal effects on sea turtles and other wildlife. Although researchers have reported on ingestion of anthropogenic debris by marine turtles and implied incidences of debris ingestion have increased over time, there has not been a global synthesis of the phenomenon since 1985. Thus, we analyzed 37 studies published from 1985 to 2012 that report on data collected from before 1900 through 2011. Specifically, we investigated whether ingestion prevalence has changed over time, what types of debris are most commonly ingested, the geographic distribution of debris ingestion by marine turtles relative to global debris distribution, and which species and life-history stages are most likely to ingest debris. The probability of green (Chelonia mydas) and leatherback turtles (Dermochelys coriacea) ingesting debris increased significantly over time, and plastic was the most commonly ingested debris. Turtles in nearly all regions studied ingest debris, but the probability of ingestion was not related to modeled debris densities. Furthermore, smaller, oceanic-stage turtles were more likely to ingest debris than coastal foragers, whereas carnivorous species were less likely to ingest debris than herbivores or gelatinovores. Our results indicate oceanic leatherback turtles and green turtles are at the greatest risk of both lethal and sublethal effects from ingested marine debris. To reduce this risk, anthropogenic debris must be managed at a global level. © 2013 The Authors. Conservation Biology published by Wiley Periodicals, Inc., on behalf of the Society for Conservation Biology.

  8. Orbiting Debris: a Space Environmental Problem. Background Paper

    Science.gov (United States)

    1990-01-01

    Artificial debris, deposited in a multitude of orbits about the Earth as the result of the exploration and use of the space environment, poses a growing hazard to future space operations. Unless nations sharply reduce the amount of orbital debris they produce, future space activites could suffer loss of capability, loss of income, and even loss of life as a result of collisions between spacecraft and debris. This background paper discusses the sources of debris and how they can be greatly reduced.

  9. Flow-R, a model for susceptibility mapping of debris flows and other gravitational hazards at a regional scale

    Directory of Open Access Journals (Sweden)

    P. Horton

    2013-04-01

    Full Text Available The development of susceptibility maps for debris flows is of primary importance due to population pressure in hazardous zones. However, hazard assessment by process-based modelling at a regional scale is difficult due to the complex nature of the phenomenon, the variability of local controlling factors, and the uncertainty in modelling parameters. A regional assessment must consider a simplified approach that is not highly parameter dependant and that can provide zonation with minimum data requirements. A distributed empirical model has thus been developed for regional susceptibility assessments using essentially a digital elevation model (DEM. The model is called Flow-R for Flow path assessment of gravitational hazards at a Regional scale (available free of charge under http://www.flow-r.org and has been successfully applied to different case studies in various countries with variable data quality. It provides a substantial basis for a preliminary susceptibility assessment at a regional scale. The model was also found relevant to assess other natural hazards such as rockfall, snow avalanches and floods. The model allows for automatic source area delineation, given user criteria, and for the assessment of the propagation extent based on various spreading algorithms and simple frictional laws. We developed a new spreading algorithm, an improved version of Holmgren's direction algorithm, that is less sensitive to small variations of the DEM and that is avoiding over-channelization, and so produces more realistic extents. The choices of the datasets and the algorithms are open to the user, which makes it compliant for various applications and dataset availability. Amongst the possible datasets, the DEM is the only one that is really needed for both the source area delineation and the propagation assessment; its quality is of major importance for the results accuracy. We consider a 10 m DEM resolution as a good compromise between processing time

  10. The physics of debris flows

    Science.gov (United States)

    Iverson, R.M.

    1997-01-01

    Recent advances in theory and experimentation motivate a thorough reassessment of the physics of debris flows. Analyses of flows of dry, granular solids and solid-fluid mixtures provide a foundation for a comprehensive debris flow theory, and experiments provide data that reveal the strengths and limitations of theoretical models. Both debris flow materials and dry granular materials can sustain shear stresses while remaining static; both can deform in a slow, tranquil mode characterized by enduring, frictional grain contacts; and both can flow in a more rapid, agitated mode characterized by brief, inelastic grain collisions. In debris flows, however, pore fluid that is highly viscous and nearly incompressible, composed of water with suspended silt and clay, can strongly mediate intergranular friction and collisions. Grain friction, grain collisions, and viscous fluid flow may transfer significant momentum simultaneously. Both the vibrational kinetic energy of solid grains (measured by a quantity termed the granular temperature) and the pressure of the intervening pore fluid facilitate motion of grains past one another, thereby enhancing debris flow mobility. Granular temperature arises from conversion of flow translational energy to grain vibrational energy, a process that depends on shear rates, grain properties, boundary conditions, and the ambient fluid viscosity and pressure. Pore fluid pressures that exceed static equilibrium pressures result from local or global debris contraction. Like larger, natural debris flows, experimental debris flows of ???10 m3 of poorly sorted, water-saturated sediment invariably move as an unsteady surge or series of surges. Measurements at the base of experimental flows show that coarse-grained surge fronts have little or no pore fluid pressure. In contrast, finer-grained, thoroughly saturated debris behind surge fronts is nearly liquefied by high pore pressure, which persists owing to the great compressibility and moderate

  11. Fission-product releases from a PHWR terminal debris bed

    Energy Technology Data Exchange (ETDEWEB)

    Brown, M.J.; Bailey, D.G., E-mail: morgan.brown@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2016-06-15

    During an unmitigated severe accident in a pressurized heavy water reactor (PHWR) with horizontal fuel channels, the core may disassemble and relocate to the bottom of the calandria vessel. The resulting heterogeneous in-vessel terminal debris bed (TDB) would likely be quenched by any remaining moderator, and some of the decay heat would be conducted through the calandria vessel shell to the surrounding reactor vault or shield tank water. As the moderator boiled off, the solid debris bed would transform into a more homogeneous molten corium pool located between top and bottom crusts. Until recently, the severe accident code MAAP-CANDU assumed that unreleased volatile and semi-volatile fission products remained in the TDB until after calandria vessel failure, due to low diffusivity through the top crust and the lack of gases or steam to flush released fission products from the debris. However, national and international experimental results indicate this assumption is unlikely; instead, high- and medium-volatility fission products would be released from a molten debris pool, and their volatility and transport should be taken into account in TDB modelling. The resulting change in the distribution of fission products within the reactor and containment, and the associated decay heat, can have significant effects upon the progression of the accident and fission-product releases to the environment. This article describes a postulated PHWR severe accident progression to generate a TDB and the effects of fission-product releases from the terminal debris, using the simple release model in the MAAP-CANDU severe accident code. It also provides insights from various experimental programs related to fission-product releases from core debris, and their applicability to the MAAP-CANDU TDB model. (author)

  12. Demonstrations and verification of debris bed models in the MEDICI reactor cavity code

    International Nuclear Information System (INIS)

    Trebilcock, W.R.; Bergeron, K.D.; Gorham-Bergeron, E.D.

    1984-01-01

    The MEDICI reactor cavity model is under development at Sandia National Laboratories to provide a simple but realistic treatment of ex-vessel severe accident phenomena. Several demonstration cases have been run and are discussed as illustrations of the model's capabilities. Verification of the model with experiments has supplied confidence in the model

  13. A NEW ALGORITHM FOR SELF-CONSISTENT THREE-DIMENSIONAL MODELING OF COLLISIONS IN DUSTY DEBRIS DISKS

    International Nuclear Information System (INIS)

    Stark, Christopher C.; Kuchner, Marc J.

    2009-01-01

    We present a new 'collisional grooming' algorithm that enables us to model images of debris disks where the collision time is less than the Poynting-Robertson (PR) time for the dominant grain size. Our algorithm uses the output of a collisionless disk simulation to iteratively solve the mass flux equation for the density distribution of a collisional disk containing planets in three dimensions. The algorithm can be run on a single processor in ∼1 hr. Our preliminary models of disks with resonant ring structures caused by terrestrial mass planets show that the collision rate for background particles in a ring structure is enhanced by a factor of a few compared to the rest of the disk, and that dust grains in or near resonance have even higher collision rates. We show how collisions can alter the morphology of a resonant ring structure by reducing the sharpness of a resonant ring's inner edge and by smearing out azimuthal structure. We implement a simple prescription for particle fragmentation and show how PR drag and fragmentation sort particles by size, producing smaller dust grains at smaller circumstellar distances. This mechanism could cause a disk to look different at different wavelengths, and may explain the warm component of dust interior to Fomalhaut's outer dust ring seen in the resolved 24 μm Spitzer image of this system.

  14. Relevance of the submillimeter fluxes on the SED modeling of debris disks. (Spanish Title: Importancia de los flujos submilimétricos en el modelado de las SED de discos debris)

    Science.gov (United States)

    García, L. H.; Gómez, M.

    The modeling of Spectral Energy Distributions (SEDs) is a generally used method to characterize the so-called debris disks. This technique requires reliable flux measurements in a wide range of wavelengths, including the IR and sub-mm regimes. However, fluxes at wavelengths larger than 100 microns are not always available. In this contribution we investigate how such measurements affect the derived parameters for a sample of 24 stars showing excesses in their SEDs. If the excesses at wavelengths larger than 70 microns exceed those for wavelengths larger than 100 microns, the sets of disks parameters derived from the SED modeling excluding and including fluxes for wavelengths larger than 100 microns roughly agree.

  15. Service Oriented Spacecraft Modeling Environment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The I-Logix team proposes development of the Service Oriented Spacecraft Modeling Environment (SOSME) to allow faster and more effective spacecraft system design...

  16. Orbital debris: a technical assessment

    National Research Council Canada - National Science Library

    National Research Council Staff; Commission on Engineering and Technical Systems; Division on Engineering and Physical Sciences; National Research Council; National Academy of Sciences

    ..., and other debris created as a byproduct of space operations. Orbital Debris examines the methods we can use to characterize orbital debris, estimates the magnitude of the debris population, and assesses the hazard that this population poses to spacecraft...

  17. Unraveling the patterns of late Holocene debris-flow activity on a cone in the Swiss Alps: Chronology, environment and implications for the future

    Science.gov (United States)

    Stoffel, Markus; Conus, Delphine; Grichting, Michael A.; Lièvre, Igor; Maître, Gilles

    2008-02-01

    Debris-flow activity on the forested cone of the Ritigraben torrent (Valais, Swiss Alps) was assessed from growth disturbances in century-old trees, providing an unusually complete record of past events and deposition of material. The study of 2246 tree-ring sequences sampled from 1102 Larix decidua Mill., Picea abies (L.) Karst. and Pinus cembra ssp. sibirica trees allowed reconstruction of 123 events since AD 1566. Geomorphic mapping permitted identification of 769 features related to past debris-flow activity on the intermediate cone. The features inventoried in the study area covering 32 ha included 291 lobes, 465 levées and 13 well-developed debris-flow channels. Based on tree-ring records of disturbed trees growing in or next to the deposits, almost 86% of the lobes identified on the present-day surface could be dated. A majority of the dated material was deposited over the last century. Signs of pre-20th century events are often recognizable in the tree-ring record of survivor trees, but the material that caused the growth anomaly in trees has been completely overridden or eroded by more recent debris-flow activity. Tree-ring records suggest that cool summers with frequent snowfalls at higher elevations regularly prevented the release of debris flows between the 1570s and 1860s; the warming trend combined with greater precipitation totals in summer and autumn between 1864 and 1895 provided conditions that were increasingly favorable for releasing events from the source zone. Enhanced debris-flow activity continued well into the 20th century and reconstructions show a clustering of events in the period 1916-1935 when warm-wet conditions prevailed during summer in the Swiss Alps. In contrast, very low activity is observed for the last 10-yr period (1996-2005) with only one debris-flow event recorded on August 27, 2002. Since sediment availability is not a limiting factor, this temporal absence of debris-flow activity is due to an absence of triggering events

  18. TREM2-transduced myeloid precursors mediate nervous tissue debris clearance and facilitate recovery in an animal model of multiple sclerosis.

    Directory of Open Access Journals (Sweden)

    Kazuya Takahashi

    2007-04-01

    Full Text Available BACKGROUND: In multiple sclerosis, inflammation can successfully be prevented, while promoting repair is still a major challenge. Microglial cells, the resident phagocytes of the central nervous system (CNS, are hematopoietic-derived myeloid cells and express the triggering receptor expressed on myeloid cells 2 (TREM2, an innate immune receptor. Myeloid cells are an accessible source for ex vivo gene therapy. We investigated whether myeloid precursor cells genetically modified to express TREM2 affect the disease course of experimental autoimmune encephalomyelitis (EAE, an animal model of multiple sclerosis. METHODS AND FINDINGS: EAE was induced in mice by immunization with a myelin autoantigen. Intravenous application of TREM2-transduced bone marrow-derived myeloid precursor cells at the EAE peak led to an amelioration of clinical symptoms, reduction in axonal damage, and prevention of further demyelination. TREM2-transduced myeloid cells applied intravenously migrated into the inflammatory spinal cord lesions of EAE-diseased mice, showed increased lysosomal and phagocytic activity, cleared degenerated myelin, and created an anti-inflammatory cytokine milieu within the CNS. CONCLUSIONS: Intravenously applied bone marrow-derived and TREM2-tranduced myeloid precursor cells limit tissue destruction and facilitate repair within the murine CNS by clearance of cellular debris during EAE. TREM2 is a new attractive target for promotion of repair and resolution of inflammation in multiple sclerosis and other neuroinflammatory diseases.

  19. Conceptual Model of Dynamic Geographic Environment

    Directory of Open Access Journals (Sweden)

    Martínez-Rosales Miguel Alejandro

    2014-04-01

    Full Text Available In geographic environments, there are many and different types of geographic entities such as automobiles, trees, persons, buildings, storms, hurricanes, etc. These entities can be classified into two groups: geographic objects and geographic phenomena. By its nature, a geographic environment is dynamic, thus, it’s static modeling is not sufficient. Considering the dynamics of geographic environment, a new type of geographic entity called event is introduced. The primary target is a modeling of geographic environment as an event sequence, because in this case the semantic relations are much richer than in the case of static modeling. In this work, the conceptualization of this model is proposed. It is based on the idea to process each entity apart instead of processing the environment as a whole. After that, the so called history of each entity and its spatial relations to other entities are defined to describe the whole environment. The main goal is to model systems at a conceptual level that make use of spatial and temporal information, so that later it can serve as the semantic engine for such systems.

  20. Elementary analysis on the bed-sediment entrainment by debris flow and its application using the TopFlowDF model

    Directory of Open Access Journals (Sweden)

    Zheng Han

    2016-03-01

    Full Text Available The Geographic Information System (GIS-based TopFlowDF model is an effective simulation tool to analyse the debris-flow propagation on the fan. It has been validated in the previous research works and shows a satisfactory accuracy. We review the framework of the model in this paper and discuss that the simulation results are rather sensitive to the input conditions (e.g. the user-defined start point and debris-flow volume. In fact, previous studies have elucidated that sediment entrainment by debris flow conspicuously influences these input conditions. In this paper, we develop an elementary static approach with a three-layer model to estimate the entrainment and determine the amplification of total mass volume and peak discharge. Subsequently a new concept of “critical line” is proposed to detect the erodible reaches in the channel. Two cases in Japan and Norway are selected to illustrate the approach; analytical results show a good agreement with the in situ survey. The presented approach can provide a better solution to the input conditions as required by TopFlowDF model.

  1. Building an environment model using depth information

    Science.gov (United States)

    Roth-Tabak, Y.; Jain, Ramesh

    1989-01-01

    Modeling the environment is one of the most crucial issues for the development and research of autonomous robot and tele-perception. Though the physical robot operates (navigates and performs various tasks) in the real world, any type of reasoning, such as situation assessment, planning or reasoning about action, is performed based on information in its internal world. Hence, the robot's intentional actions are inherently constrained by the models it has. These models may serve as interfaces between sensing modules and reasoning modules, or in the case of telerobots serve as interface between the human operator and the distant robot. A robot operating in a known restricted environment may have a priori knowledge of its whole possible work domain, which will be assimilated in its World Model. As the information in the World Model is relatively fixed, an Environment Model must be introduced to cope with the changes in the environment and to allow exploring entirely new domains. Introduced here is an algorithm that uses dense range data collected at various positions in the environment to refine and update or generate a 3-D volumetric model of an environment. The model, which is intended for autonomous robot navigation and tele-perception, consists of cubic voxels with the possible attributes: Void, Full, and Unknown. Experimental results from simulations of range data in synthetic environments are given. The quality of the results show great promise for dealing with noisy input data. The performance measures for the algorithm are defined, and quantitative results for noisy data and positional uncertainty are presented.

  2. MATLAB/Simulink analytic radar modeling environment

    Science.gov (United States)

    Esken, Bruce L.; Clayton, Brian L.

    2001-09-01

    Analytic radar models are simulations based on abstract representations of the radar, the RF environment that radar signals are propagated, and the reflections produced by targets, clutter and multipath. These models have traditionally been developed in FORTRAN and have evolved over the last 20 years into efficient and well-accepted codes. However, current models are limited in two primary areas. First, by the nature of algorithm based analytical models, they can be difficult to understand by non-programmers and equally difficult to modify or extend. Second, there is strong interest in re-using these models to support higher-level weapon system and mission level simulations. To address these issues, a model development approach has been demonstrated which utilizes the MATLAB/Simulink graphical development environment. Because the MATLAB/Simulink environment graphically represents model algorithms - thus providing visibility into the model - algorithms can be easily analyzed and modified by engineers and analysts with limited software skills. In addition, software tools have been created that provide for the automatic code generation of C++ objects. These objects are created with well-defined interfaces enabling them to be used by modeling architectures external to the MATLAB/Simulink environment. The approach utilized is generic and can be extended to other engineering fields.

  3. Earth Satellite Population Instability: Underscoring the Need for Debris Mitigation

    Science.gov (United States)

    Liou, Jer-chyi; Johnson, N. L.

    2006-01-01

    the number density of satellites is above a critical spatial density, the production rate of new satellites (i.e., debris) due to collisions exceeds the loss of objects due to orbital decay. NASA s evolutionary satellite population model LEGEND (LEO-to-GEO Environment Debris model), developed by the Orbital Debris Program Office at the NASA Lyndon B. Johnson Space Center, is a high fidelity three-dimensional physical model that is capable of simulating the historical satellite environment, as well as the evolution of future debris populations (14, 15). The subject study assumed no rocket bodies and spacecraft were launched after December 2004, and no future disposal maneuvers were allowed for existing spacecraft, few of which currently have such a capability. The rate of satellite explosions would naturally decrease to zero within a few decades as the current satellite population ages. The LEGEND future projection adopts a Monte Carlo approach to simulate future on-orbit explosions and collisions. Within a given projection time step, once the explosion probability is estimated for an intact object, a random number is drawn and compared with the probability to determine if an explosion would occur. A similar procedure is applied to collisions for each pair of target and projectile involved within the same time step. Due to the nature of the Monte Carlo process, multiple projection runs must be performed and analyzed before one can draw reliable and meaningful conclusions from the outcome. A total of fifty, 200-year future projection Monte Carlo simulations were executed and evaluated (16).

  4. Charging of Space Debris and Their Dynamical Consequences

    Science.gov (United States)

    2016-01-08

    satellite orbital altitudes (particularly in the low earth orbit (LEO) region) and the risk they pose for space assets has attracted a great deal of...SUPPLEMENTARY NOTES 14. ABSTRACT The charging of space debris due to the ambient plasma environment in the low earth orbit (LEO) and geostationary earth... orbit (GEO) regions of the ionosphere has been investigated using both analytic and particle-in-cell (PIC) modeling. The analytic estimates have been

  5. Analysis and reconstructed modelling of the debris flow event of the 21st of July 2012 of St. Lorenzen (Styria, Austira)

    Science.gov (United States)

    Janu, Stefan; Mehlhorn, Susanne; Moser, Markus

    2013-04-01

    Analysis and reconstructed modelling of the debris flow event of the 21st of July 2012 of St. Lorenzen (Styria, Austria) Authors: Stefan Janu, Susanne Mehlhorn, Markus Moser The village of St. Lorenzen, in the Styrian Palten valley is situated on the banks of the Lorenz torrent, in which a debris flow event occurred in the early morning hours of the 21st of July 2012, causing catastrophic damage to residential buildings and other infrastructural facilities. In the ministry-approved hazard zone map of 2009, the flood water discharge and bedload volume associated with a 150-year event was estimated at 34 m³/s and 25,000 m³ respectively for the 5.84 km² catchment area. The bedload transport capacity of the torrent was classified as ranging from 'heavy' to 'capable of producing debris flows'. The dominant process type of the mass movement event may be described as a fine-grained debris flow. The damage in the residential area of St.Lorenzen was caused by a debris flow pulse in the lower reach of the Lorenz torrent. This debris flow pulse was in turn caused by numerous landslides along the middle reaches of the torrent, some of which caused blockages, ultimately leading to an outburst event in the main torrent. Discharge cross-sections ranging from 65 - 90 m², and over 100 m² in a few instances, were measured upstream of the St. Lorenzen residential area. Back-calculations of velocities yielded an average debris flow velocity along the middle reaches of the torrent between 11 and 16 m/s. An average velocity of 9 m/s was calculated for the debris flow at the neck of the alluvial fan directly behind the center of the village. Due to both the high discharge values as well as to the height of the mass movement deposits, the natural hazard event of 21 July 2012 in St. Lorenzen is clearly to be described as having had an extreme intensity. A total of 67 buildings were damaged along the Lorenz torrent, 7 of were completely destroyed. According to the Austrian Service for

  6. On the Solar System-Debris Disk Connecction

    OpenAIRE

    Moro-Martin, Amaya

    2007-01-01

    This paper emphasizes the connection between solar and extra-solar debris disks: how models and observations of the Solar System are helping us understand the debris disk phenomenon, and vice versa, how debris disks are helping us place our Solar System into context.

  7. The national operational environment model (NOEM)

    Science.gov (United States)

    Salerno, John J.; Romano, Brian; Geiler, Warren

    2011-06-01

    The National Operational Environment Model (NOEM) is a strategic analysis/assessment tool that provides insight into the complex state space (as a system) that is today's modern operational environment. The NOEM supports baseline forecasts by generating plausible futures based on the current state. It supports what-if analysis by forecasting ramifications of potential "Blue" actions on the environment. The NOEM also supports sensitivity analysis by identifying possible pressure (leverage) points in support of the Commander that resolves forecasted instabilities, and by ranking sensitivities in a list for each leverage point and response. The NOEM can be used to assist Decision Makers, Analysts and Researchers with understanding the inter-workings of a region or nation state, the consequences of implementing specific policies, and the ability to plug in new operational environment theories/models as they mature. The NOEM is built upon an open-source, license-free set of capabilities, and aims to provide support for pluggable modules that make up a given model. The NOEM currently has an extensive number of modules (e.g. economic, security & social well-being pieces such as critical infrastructure) completed along with a number of tools to exercise them. The focus this year is on modeling the social and behavioral aspects of a populace within their environment, primarily the formation of various interest groups, their beliefs, their requirements, their grievances, their affinities, and the likelihood of a wide range of their actions, depending on their perceived level of security and happiness. As such, several research efforts are currently underway to model human behavior from a group perspective, in the pursuit of eventual integration and balance of populace needs/demands within their respective operational environment and the capacity to meet those demands. In this paper we will provide an overview of the NOEM, the need for and a description of its main components

  8. The dynamic radiation environment assimilation model (DREAM)

    Energy Technology Data Exchange (ETDEWEB)

    Reeves, Geoffrey D [Los Alamos National Laboratory; Koller, Josef [Los Alamos National Laboratory; Tokar, Robert L [Los Alamos National Laboratory; Chen, Yue [Los Alamos National Laboratory; Henderson, Michael G [Los Alamos National Laboratory; Friedel, Reiner H [Los Alamos National Laboratory

    2010-01-01

    The Dynamic Radiation Environment Assimilation Model (DREAM) is a 3-year effort sponsored by the US Department of Energy to provide global, retrospective, or real-time specification of the natural and potential nuclear radiation environments. The DREAM model uses Kalman filtering techniques that combine the strengths of new physical models of the radiation belts with electron observations from long-term satellite systems such as GPS and geosynchronous systems. DREAM includes a physics model for the production and long-term evolution of artificial radiation belts from high altitude nuclear explosions. DREAM has been validated against satellites in arbitrary orbits and consistently produces more accurate results than existing models. Tools for user-specific applications and graphical displays are in beta testing and a real-time version of DREAM has been in continuous operation since November 2009.

  9. Flow characteristics of counter-current flow in debris bed

    International Nuclear Information System (INIS)

    Abe, Yutaka; Adachi, Hiromichi

    2004-01-01

    In the course of a severe accident, a damaged core would form a debris bed consisting of once-molten and fragmented fuel elements. It is necessary to evaluate the dryout heat flux for the judgment of the coolability of the debris bed during the severe accident. The dryout phenomena in the debris bed is dominated by the counter-current flow limitation (CCFL) in the debris bed. In this study, air-water counter-current flow behavior in the debris bed is experimentally investigated with glass particles simulating the debris beds. In this experiment, falling water flow rate and axial pressure distributions were experimentally measured. As the results, it is clarified that falling water flow rate becomes larger with the debris bed height and the pressure gradient in the upper region of the debris bed is different from that in the lower region of the debris bed. These results indicate that the dominant region for CCFL in the debris bed is identified near the top of the debris bed. Analytical results with annular flow model indicates that interfacial shear stress in the upper region of the debris bed is larger than that in the lower region of the debris bed. (author)

  10. Modeling end-of-life pathways of construction and demolition debris in the United States (poster for LCM 2017)

    Science.gov (United States)

    In 2013, the United States generated 530 million tons of construction and demolition debris (CDD), 90% of which was related to demolition. Despite this major contribution to national waste streams, Life Cycle Assessment (LCA) studies and product declarations of buildings and buil...

  11. Class-conditional feature modeling for ignitable liquid classification with substantial substrate contribution in fire debris analysis

    NARCIS (Netherlands)

    Lopatka, M.; Sigman, M.E.; Sjerps, M.J.; Williams, M.R.; Vivó-Truyols, G.

    2015-01-01

    Forensic chemical analysis of fire debris addresses the question of whether ignitable liquid residue is present in a sample and, if so, what type. Evidence evaluation regarding this question is complicated by interference from pyrolysis products of the substrate materials present in a fire. A method

  12. Monitoring and Modelling Lakes and Coastal Environments

    Science.gov (United States)

    Odada, Eric

    2009-01-01

    The monitoring and modeling of lakes and coastal environments is becoming ever more important, particularly because these environments bear heavy loads in terms of human population, and their resources are critical to the livelihoods and well-being of coastal inhabitants and ecosystems. Monitoring and Modelling Lakes and Coastal Environments is a collection of 18 papers arising from the Lake 2004 International Conference on Conservation, Restoration and Management of Lakes and Coastal Wetlands, held in Bhubaneswar, Orissa, India, 9-13 December 2004. Consequently, 15 of the papers are concerned with studies on the Indian subcontinent, and many of the papers focus on India's Lake Chilika, the site of a special session during the conference. Two papers concern Japan, and one focuses on North America's Great Lakes region. Although the book has a regional bias, the replication of best practices that can be drawn from these studies may be useful for an international audience.

  13. Observations on Marine Debris at Coastal Areas of Takalar District and Makassar City South Sulawesi

    OpenAIRE

    Tahir, Akbar; Werorilangi, Shinta; Zulkarnaen, Adi; Isman, Fajar Mulana; Faisal, Ahmad

    2017-01-01

    Marine debris is defined as material that is solid, persistent, manufactured or processed, and deliberately or not-deliberately left in the marine environment. Marine debris comes in many shapes and forms, ranging in size from microscopic microplastics to large vessels. Marine debris is a big and growing global problem, pose threats to marine life sustainability. Plastic is a major component of marine debris, and single use packaging accounts for an increasing part of the global marine debris...

  14. A generic Froude scale model study of massive bedload deposition in a debris basin

    Science.gov (United States)

    Piton, Guillaume; Recking, Alain

    2017-04-01

    Sediment trapping structures, such as gravel deposition basins, are regularly implemented in mountainous context for flood hazard mitigation. These structures should ultimately trap gravels when their excess may aggravate the downstream flood hazard, while, the remaining time, allowing a suitable background sediment continuity. Such optimized designs require a sufficient knowledge of the flow features and geomorphic processes implied in gravel trapping. A generic Froude scale model of a 10%-steep, bedload deposition basin, with a slit dam and without outlet structure, is presented in this work. Accurate photogrammetry and large scale particle image velocimetry (LS-PIV) were combined to study the geomorphic patterns and to reconstruct the flows. The emergence of self induced cycles of braided and channelized flows, with intense grain size sorting, is described. It sheds light on the similarity of bedload trapping with alluvial fan formation or fluvial delta development. The deposition slope, a key parameter in the structure design, is more precisely studied. The measurements are correctly estimated by a new simple equation, which is developed from prior works dedicated to steep slope stream hydraulics and bedload transport. The analysis demonstrates additionally that, despite the steepness of the studied conditions, most flows are subcritical due to roughness adjustment. We finally highlight that morphologically-active flows, i.e., with dimensionless shear stress higher than the threshold for motion, have Froude number ≈ 1; i.e., that a critical flow hypothesis seems reasonable, as a first approximation, to describe flows over massive bedload depositions. This new dataset, with complete geomorphic and flow measurements, in diverse conditions, may be used as reference to try and test numerical approaches of the phenomena.

  15. Prevention of debris flow disasters on Chengdu-Kunming Railway.

    Science.gov (United States)

    Wang, W; Xu, W L; Liu, S J

    2001-07-01

    Chengdu-Kunming Railway is an important transport line on southwestern China. However, this railway's safety is often threatened by debris flows. How to effectively forecast and alarm the debris flow disasters and reduce the losses is the aim to study the prevention system in this paper. The factors to cause or influence debris flow are divided into four parts--the basin environmental factors, the basin meteoric factors, the prevention work's elements and the flood-relief work's elements, and the prevention system is made up of three models--a judgment model to assess the debris flow gully's seriousness, a forecast model to predict the debris flow's occurrence and an alarm model to evaluate the debris flow's disaster. Afterwards, a concise structure chart is worked out and verified by the field data from Chengdu-Kunming Railway. This prevention system will provide beneficial reference for the debris flow's monitoring network to be executed on Chengdu-Kunming Railway.

  16. Marketing research model of competitive environment

    Directory of Open Access Journals (Sweden)

    Krasilya Dmitriy

    2015-11-01

    Full Text Available To support its competitive advantages in current market conditions, each company needs to choose better ways of guaranteeing its favorable competitive position. In this regard, considerable interest lies in the structuring and algorithmization of marketing research processes that provide the information background of such choice. The article is devoted to modeling the process of marketing research of competitive environment.

  17. Reading the Signatures of Extrasolar Planets in Debris Disks

    Science.gov (United States)

    Kuchner, Marc J.

    2009-01-01

    An extrasolar planet sculpts the famous debris dish around Fomalhaut; probably ma ny other debris disks contain planets that we could locate if only we could better recognize their signatures in the dust that surrounds them. But the interaction between planets and debris disks involves both orbital resonances and collisions among grains and rocks in the disks --- difficult processes to model simultanemus]y. I will describe new 3-D models of debris disk dynamics that incorporate both collisions and resonant trapping of dust for the first time, allowing us to decode debris disk images and read the signatures of the planets they contain.

  18. Mathematical modelling of tsunami impacts on critical infrastructures: exposure and severity associated with debris transport at Sines port, Portugal.

    Science.gov (United States)

    Conde, Daniel; Baptista, Maria Ana; Sousa Oliveira, Carlos; Ferreira, Rui M. L.

    2015-04-01

    a flux-splitting technique with a reviewed Roe-Riemann solver and appropriate source-term formulations to ensure full conservativeness. Additionally, STAV-2D features Lagrangian-Eulerian coupling enabling solid transport simulation under both continuum and discrete approaches, and has been validated with both laboratory data and paleo-tsunami evidence (Conde, 2013a; Conde, 2013b). The interactions between the inundating flow and coal stockpiles or natural mobile bed reaches were simulated using a continuum debris-flow approach, featuring fractional solid transport, while the containers at the new terminal were advected with an explicit Lagrangian method. The meshwork employed at the port models the existing geometry and structures in great detail, enabling explicitly resolved interactions between the current infrastructure and the overland propagating tsunami. The obtained preliminary results suggest that several structures, some of them critical in a nationwide context, are exposed to tsunami actions. The coal deposition pattern and the final location of monitored containers were determined for two magnitude scenarios (8.5 Mw and 9.5 Mw) in the case of a tsunami generated at the Horseshoe fault and one magnitude scenario (9.5 Mw) for a tsunami generated at the Gorringe bank. The inland washing of the coal stockpiles may impose great loss of both economical and environmental value, while the impact of large mobile debris, such as the containers in the terminal area, significantly increases the severity of infrastructural damage. Acknowledgements This work was partially funded by FEDER, program COMPETE, and by national funds through the Portuguese Foundation for Science and Technology (FCT) with project RECI/ECM-HID/0371/2012. References Baptista M.A. & Miranda, J.M. (2009), Revision of the Portuguese catalog of tsunamis. Nat. Hazards Earth Syst. Sci., 9, 25-42. Canelas, R.; Murillo, J. & Ferreira, R.M.L. (2013), Two-dimensional depth-averaged modelling of dam

  19. Space Debris Removal: A Game Theoretic Analysis

    Directory of Open Access Journals (Sweden)

    Richard Klima

    2016-08-01

    Full Text Available We analyse active space debris removal efforts from a strategic, game-theoretical perspective. Space debris is non-manoeuvrable, human-made objects orbiting Earth, which pose a significant threat to operational spacecraft. Active debris removal missions have been considered and investigated by different space agencies with the goal to protect valuable assets present in strategic orbital environments. An active debris removal mission is costly, but has a positive effect for all satellites in the same orbital band. This leads to a dilemma: each agency is faced with the choice between the individually costly action of debris removal, which has a positive impact on all players; or wait and hope that others jump in and do the ‘dirty’ work. The risk of the latter action is that, if everyone waits, the joint outcome will be catastrophic, leading to what in game theory is referred to as the ‘tragedy of the commons’. We introduce and thoroughly analyse this dilemma using empirical game theory and a space debris simulator. We consider two- and three-player settings, investigate the strategic properties and equilibria of the game and find that the cost/benefit ratio of debris removal strongly affects the game dynamics.

  20. Near Field Environment Process Model Report

    Energy Technology Data Exchange (ETDEWEB)

    R.A. Wagner

    2000-11-14

    Waste emplacement and activities associated with construction of a repository system potentially will change environmental conditions within the repository system. These environmental changes principally result from heat generated by the decay of the radioactive waste, which elevates temperatures within the repository system. Elevated temperatures affect distribution of water, increase kinetic rates of geochemical processes, and cause stresses to change in magnitude and orientation from the stresses resulting from the overlying rock and from underground construction activities. The recognition of this evolving environment has been reflected in activities, studies and discussions generally associated with what has been termed the Near-Field Environment (NFE). The NFE interacts directly with waste packages and engineered barriers as well as potentially changing the fluid composition and flow conditions within the mountain. As such, the NFE defines the environment for assessing the performance of a potential Monitored Geologic Repository at Yucca Mountain, Nevada. The NFe evolves over time, and therefore is not amenable to direct characterization or measurement in the ambient system. Analysis or assessment of the NFE must rely upon projections based on tests and models that encompass the long-term processes of the evolution of this environment. This NFE Process Model Report (PMR) describes the analyses and modeling based on current understanding of the evolution of the near-field within the rock mass extending outward from the drift wall.

  1. Modeling tritium transport in the environment

    International Nuclear Information System (INIS)

    Murphy, C.E. Jr.

    1986-01-01

    A model of tritium transport in the environment near an atmospheric source of tritium is presented in the general context of modeling material cycling in ecosystems. The model was developed to test hypotheses about the process involved in tritium cycling. The temporal and spatial scales of the model were picked to allow comparison to environmental monitoring data collected in the vicinity of the Savannah River Plant. Initial simulations with the model showed good agreement with monitoring data, including atmospheric and vegetation tritium concentrations. The model can also simulate values of tritium in vegetation organic matter if the key parameter distributing the source of organic hydrogen is varied to fit the data. However, because of the lack of independent conformation of the distribution parameter, there is still uncertainty about the role of organic movement of tritium in the food chain, and its effect on the dose to man

  2. Anthropogenic Debris Ingestion by Avifauna in Eastern Australia.

    Science.gov (United States)

    Roman, Lauren; Schuyler, Qamar A; Hardesty, Britta Denise; Townsend, Kathy A

    2016-01-01

    Anthropogenic debris in the world's oceans and coastal environments is a pervasive global issue that has both direct and indirect impacts on avifauna. The number of bird species affected, the feeding ecologies associated with an increased risk of debris ingestion, and selectivity of ingested debris have yet to be investigated in most of Australia's coastal and marine birds. With this study we aim to address the paucity of data regarding marine debris ingestion in Australian coastal and marine bird species. We investigated which Australian bird groups ingest marine debris, and whether debris-ingesting groups exhibit selectivity associated with their taxonomy, habitat or foraging methods. Here we present the largest multispecies study of anthropogenic debris ingestion in Australasian avifauna to date. We necropsied and investigated the gastrointestinal contents of 378 birds across 61 species, collected dead across eastern Australia. These species represented nine taxonomic orders, five habitat groups and six feeding strategies. Among investigated species, thirty percent had ingested debris, though ingestion did not occur uniformly within the orders of birds surveyed. Debris ingestion was found to occur in orders Procellariiformes, Suliformes, Charadriiformes and Pelecaniformes, across all surveyed habitats, and among birds that foraged by surface feeding, pursuit diving and search-by-sight. Procellariiformes, birds in pelagic habitats, and surface feeding marine birds ingested debris with the greatest frequency. Among birds which were found to ingest marine debris, we investigated debris selectivity and found that marine birds were selective with respect to both type and colour of debris. Selectivity for type and colour of debris significantly correlated with taxonomic order, habitat and foraging strategy. This study highlights the significant impact of feeding ecology on debris ingestion among Australia's avifauna.

  3. Anthropogenic Debris Ingestion by Avifauna in Eastern Australia.

    Directory of Open Access Journals (Sweden)

    Lauren Roman

    Full Text Available Anthropogenic debris in the world's oceans and coastal environments is a pervasive global issue that has both direct and indirect impacts on avifauna. The number of bird species affected, the feeding ecologies associated with an increased risk of debris ingestion, and selectivity of ingested debris have yet to be investigated in most of Australia's coastal and marine birds. With this study we aim to address the paucity of data regarding marine debris ingestion in Australian coastal and marine bird species. We investigated which Australian bird groups ingest marine debris, and whether debris-ingesting groups exhibit selectivity associated with their taxonomy, habitat or foraging methods. Here we present the largest multispecies study of anthropogenic debris ingestion in Australasian avifauna to date. We necropsied and investigated the gastrointestinal contents of 378 birds across 61 species, collected dead across eastern Australia. These species represented nine taxonomic orders, five habitat groups and six feeding strategies. Among investigated species, thirty percent had ingested debris, though ingestion did not occur uniformly within the orders of birds surveyed. Debris ingestion was found to occur in orders Procellariiformes, Suliformes, Charadriiformes and Pelecaniformes, across all surveyed habitats, and among birds that foraged by surface feeding, pursuit diving and search-by-sight. Procellariiformes, birds in pelagic habitats, and surface feeding marine birds ingested debris with the greatest frequency. Among birds which were found to ingest marine debris, we investigated debris selectivity and found that marine birds were selective with respect to both type and colour of debris. Selectivity for type and colour of debris significantly correlated with taxonomic order, habitat and foraging strategy. This study highlights the significant impact of feeding ecology on debris ingestion among Australia's avifauna.

  4. Prediction of Foreign Object Debris/Damage type based in human factors for aeronautics using logistic regression model

    Science.gov (United States)

    Romo, David Ricardo

    Foreign Object Debris/Damage (FOD) has been an issue for military and commercial aircraft manufacturers since the early ages of aviation and aerospace. Currently, aerospace is growing rapidly and the chances of FOD presence are growing as well. One of the principal causes in manufacturing is the human error. The cost associated with human error in commercial and military aircrafts is approximately accountable for 4 billion dollars per year. This problem is currently addressed with prevention programs, elimination techniques, and designation of FOD areas, controlled access, restrictions of personal items entering designated areas, tool accountability, and the use of technology such as Radio Frequency Identification (RFID) tags, etc. All of the efforts mentioned before, have not show a significant occurrence reduction in terms of manufacturing processes. On the contrary, a repetitive path of occurrence is present, and the cost associated has not declined in a significant manner. In order to address the problem, this thesis proposes a new approach using statistical analysis. The effort of this thesis is to create a predictive model using historical categorical data from an aircraft manufacturer only focusing in human error causes. The use of contingency tables, natural logarithm of the odds and probability transformation is used in order to provide the predicted probabilities of each aircraft. A case of study is shown in this thesis in order to show the applied methodology. As a result, this approach is able to predict the possible outcomes of FOD by the workstation/area needed, and monthly predictions per workstation. This thesis is intended to be the starting point of statistical data analysis regarding FOD in human factors. The purpose of this thesis is to identify the areas where human error is the primary cause of FOD occurrence in order to design and implement accurate solutions. The advantages of the proposed methodology can go from the reduction of cost

  5. The MELTSPREAD Code for Modeling of Ex-Vessel Core Debris Spreading Behavior, Code Manual – Version3-beta

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, M. T. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-09-01

    MELTSPREAD3 is a transient one-dimensional computer code that has been developed to predict the gravity-driven flow and freezing behavior of molten reactor core materials (corium) in containment geometries. Predictions can be made for corium flowing across surfaces under either dry or wet cavity conditions. The spreading surfaces that can be selected are steel, concrete, a user-specified material (e.g., a ceramic), or an arbitrary combination thereof. The corium can have a wide range of compositions of reactor core materials that includes distinct oxide phases (predominantly Zr, and steel oxides) plus metallic phases (predominantly Zr and steel). The code requires input that describes the containment geometry, melt “pour” conditions, and cavity atmospheric conditions (i.e., pressure, temperature, and cavity flooding information). For cases in which the cavity contains a preexisting water layer at the time of RPV failure, melt jet breakup and particle bed formation can be calculated mechanistically given the time-dependent melt pour conditions (input data) as well as the heatup and boiloff of water in the melt impingement zone (calculated). For core debris impacting either the containment floor or previously spread material, the code calculates the transient hydrodynamics and heat transfer which determine the spreading and freezing behavior of the melt. The code predicts conditions at the end of the spreading stage, including melt relocation distance, depth and material composition profiles, substrate ablation profile, and wall heatup. Code output can be used as input to other models such as CORQUENCH that evaluate long term core-concrete interaction behavior following the transient spreading stage. MELTSPREAD3 was originally developed to investigate BWR Mark I liner vulnerability, but has been substantially upgraded and applied to other reactor designs (e.g., the EPR), and more recently to the plant accidents at Fukushima Daiichi. The most recent round of

  6. Canadian Activities in Space Debris Mitigation Technologies

    Science.gov (United States)

    Nikanpour, Darius; Jiang, Xin Xiang; Goroshin, Samuel; Haddad, Emile; Kruzelecky, Roman; Hoa, Suong; Merle, Philippe; Kleiman, Jacob; Gendron, Stephane; Higgins, Andrew; Jamroz, Wes

    The space environment, and in particular the Low Earth Orbit (LEO), is becoming increasingly populated with space debris which include fragments of dysfunctional spacecraft parts and materials traveling at speeds up to 15 km per second. These pose an escalating potential threat to LEO spacecraft, the international space station, and manned missions. This paper presents the Canadian activities to address the concerns over space debris in terms of debris mitigation measures and technologies; these include novel spacecraft demise technologies to safely decommission the spacecraft at the end of the mission, integrated self-healing material technologies for spacecraft structures to facilitate self-repair and help maintain the spacecraft structural and thermal performance, hypervelocity ground test capability to predict the impact of space debris on spacecraft performance, and ways of raising awareness within the space community through participation in targeted Science and Technology conferences and international forums.

  7. Modelling Environment Changes for Pricing Weather Derivatives

    Directory of Open Access Journals (Sweden)

    Kabaivanov Stanimir

    2017-12-01

    Full Text Available This paper focuses on modelling environment changes in a way that allows to price weather derivatives in a flexible and efficient way. Applications and importance of climate and weather contracts extends beyond financial markets and hedging as they can be used as complementary tools for risk assessment. In addition, option-based approach toward resource management can offer very special insights on rare-events and allow to reuse derivative pricing methods to improve natural resources management. To demonstrate this general concept, we use Monte Carlo and stochastic modelling of temperatures to evaluate weather options. Research results are accompanied by R and Python code.

  8. Algorithms for the Computation of Debris Risks

    Science.gov (United States)

    Matney, Mark

    2017-01-01

    Determining the risks from space debris involve a number of statistical calculations. These calculations inevitably involve assumptions about geometry - including the physical geometry of orbits and the geometry of non-spherical satellites. A number of tools have been developed in NASA's Orbital Debris Program Office to handle these calculations; many of which have never been published before. These include algorithms that are used in NASA's Orbital Debris Engineering Model ORDEM 3.0, as well as other tools useful for computing orbital collision rates and ground casualty risks. This paper will present an introduction to these algorithms and the assumptions upon which they are based.

  9. Algorithms for the Computation of Debris Risk

    Science.gov (United States)

    Matney, Mark J.

    2017-01-01

    Determining the risks from space debris involve a number of statistical calculations. These calculations inevitably involve assumptions about geometry - including the physical geometry of orbits and the geometry of satellites. A number of tools have been developed in NASA’s Orbital Debris Program Office to handle these calculations; many of which have never been published before. These include algorithms that are used in NASA’s Orbital Debris Engineering Model ORDEM 3.0, as well as other tools useful for computing orbital collision rates and ground casualty risks. This paper presents an introduction to these algorithms and the assumptions upon which they are based.

  10. Architecture of the Product State Model Environment

    DEFF Research Database (Denmark)

    Holm Larsen, Michael; Lynggaard, Hans Jørgen B.

    2003-01-01

    This paper addresses the issue of using product models to support product lifecycle activities withparticular focus on the production phase. The motivation of the research is that products are producedmore costly and with longer lead-time than necessary.The paper provides a review of product...... modelling technologies and approaches, and the overallarchitecture for the Product State Model (PSM) Environment as a basis for quality monitoring.Especially, the paper focuses on the circumstances prevailing in a one-of-a-kind manufacturingenvironment like the shipbuilding industry, where product modelling...... technologies already haveproved their worth in the design and engineering phases of shipbuilding and in the operation phase.However, the handling of product information on the shop floor is not yet equally developed.The paper reports from the Brite-Euram project (No. BE97-4510) QualiGlobe focusing...

  11. Dynamic Radiation Environment Assimilation Model: DREAM

    Science.gov (United States)

    Reeves, G. D.; Chen, Y.; Cunningham, G. S.; Friedel, R. W. H.; Henderson, M. G.; Jordanova, V. K.; Koller, J.; Morley, S. K.; Thomsen, M. F.; Zaharia, S.

    2012-03-01

    The Dynamic Radiation Environment Assimilation Model (DREAM) was developed to provide accurate, global specification of the Earth's radiation belts and to better understand the physical processes that control radiation belt structure and dynamics. DREAM is designed using a modular software approach in order to provide a computational framework that makes it easy to change components such as the global magnetic field model, radiation belt dynamics model, boundary conditions, etc. This paper provides a broad overview of the DREAM model and a summary of some of the principal results to date. We describe the structure of the DREAM model, describe the five major components, and illustrate the various options that are available for each component. We discuss how the data assimilation is performed and the data preprocessing and postprocessing that are required for producing the final DREAM outputs. We describe how we apply global magnetic field models for conversion between flux and phase space density and, in particular, the benefits of using a self-consistent, coupled ring current-magnetic field model. We discuss some of the results from DREAM including testing of boundary condition assumptions and effects of adding a source term to radial diffusion models. We also describe some of the testing and validation of DREAM and prospects for future development.

  12. TRUST MANAGEMENT MODEL FOR CLOUD COMPUTING ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Somesh Kumar Prajapati

    2013-04-01

    Full Text Available Software as a service or (SaaS is a new software development and deployment paradigm over the cloud and offers Information Technology services dynamically as “on-demand” basis over the internet. Trust is one of the fundamental security concepts on storing and delivering such services. In general, trust factors are integrated into such existent security frameworks in order to add a security level to entities collaborations through the trust relationship. However, deploying trust factor in the secured cloud environment are more complex engineering task due to the existence of heterogeneous types of service providers and consumers. In this paper, a formal trust management model has been introduced to manage the trust and its properties for SaaS in cloud computing environment. The model is capable to represent the direct trust, recommended trust, reputation etc, formally. For the analysis of the trust properties in the cloud environment, the proposed approach estimates the trust value and uncertainty of each peer by computing decay function, number of positive interactions, reputation factor and satisfaction level for the collected information.

  13. A globally complete map of supraglacial debris cover and a new toolkit for debris cover research

    Science.gov (United States)

    Herreid, Sam; Pellicciotti, Francesca

    2017-04-01

    A growing canon of literature is focused on resolving the processes and implications of debris cover on glaciers. However, this work is often confined to a handful of glaciers that were likely selected based on criteria optimizing their suitability to test a specific hypothesis or logistical ease. The role of debris cover in a glacier system is likely to not go overlooked in forthcoming research, yet the magnitude of this role at a global scale has not yet been fully described. Here, we present a map of debris cover for all glacierized regions on Earth including the Greenland Ice Sheet using 30 m Landsat data. This dataset will begin to open a wider context to the high quality, localized findings from the debris-covered glacier research community and help inform large-scale modeling efforts. A global map of debris cover also facilitates analysis attempting to isolate first order geomorphological and climate controls of supraglacial debris production. Furthering the objective of expanding the inclusion of debris cover in forthcoming research, we also present an under development suite of open-source, Python based tools. Requiring minimal and often freely available input data, we have automated the mapping of: i) debris cover, ii) ice cliffs, iii) debris cover evolution over the Landsat era and iv) glacier flow instabilities from altered debris structures. At the present time, debris extent is the only globally complete quantity but with the expanding repository of high quality global datasets and further tool development minimizing manual tasks and computational cost, we foresee all of these tools being applied globally in the near future.

  14. Modelling of Indoor Environments Using Lindenmayer Systems

    Science.gov (United States)

    Peter, M.

    2017-09-01

    Documentation of the "as-built" state of building interiors has gained a lot of interest in the recent years. Various data acquisition methods exist, e.g. the extraction from photographed evacuation plans using image processing or, most prominently, indoor mobile laser scanning. Due to clutter or data gaps as well as errors during data acquisition and processing, automatic reconstruction of CAD/BIM-like models from these data sources is not a trivial task. Thus it is often tried to support reconstruction by general rules for the perpendicularity and parallelism which are predominant in man-made structures. Indoor environments of large, public buildings, however, often also follow higher-level rules like symmetry and repetition of e.g. room sizes and corridor widths. In the context of reconstruction of city city elements (e.g. street networks) or building elements (e.g. façade layouts), formal grammars have been put to use. In this paper, we describe the use of Lindenmayer systems - which originally have been developed for the computer-based modelling of plant growth - to model and reproduce the layout of indoor environments in 2D.

  15. MODELLING OF INDOOR ENVIRONMENTS USING LINDENMAYER SYSTEMS

    Directory of Open Access Journals (Sweden)

    M. Peter

    2017-09-01

    Full Text Available Documentation of the “as-built” state of building interiors has gained a lot of interest in the recent years. Various data acquisition methods exist, e.g. the extraction from photographed evacuation plans using image processing or, most prominently, indoor mobile laser scanning. Due to clutter or data gaps as well as errors during data acquisition and processing, automatic reconstruction of CAD/BIM-like models from these data sources is not a trivial task. Thus it is often tried to support reconstruction by general rules for the perpendicularity and parallelism which are predominant in man-made structures. Indoor environments of large, public buildings, however, often also follow higher-level rules like symmetry and repetition of e.g. room sizes and corridor widths. In the context of reconstruction of city city elements (e.g. street networks or building elements (e.g. fac¸ade layouts, formal grammars have been put to use. In this paper, we describe the use of Lindenmayer systems - which originally have been developed for the computer-based modelling of plant growth - to model and reproduce the layout of indoor environments in 2D.

  16. Space Debris and Observational Astronomy

    Science.gov (United States)

    Seitzer, Patrick

    2018-01-01

    Since the launch of Sputnik 1 in 1957, astronomers have faced an increasing number of artificial objects contaminating their images of the night sky. Currently almost 17000 objects larger than 10 cm are tracked and have current orbits in the public catalog. Active missions are only a small fraction of these objects. Most are inactive satellites, rocket bodies, and fragments of larger objects: all space debris. Several mega-constellations are planned which will increase this number by 20% or more in low Earth orbit (LEO). In terms of observational astronomy, this population of Earth orbiting objects has three implications: 1) the number of streaks and glints from spacecraft will only increase. There are some practical steps that can be taken to minimize the number of such streaks and glints in astronomical imaging data. 2) The risk to damage to orbiting astronomical telescopes will only increase, particularly those in LEO. 3) If you are working on a plan for an orbiting telescope project, then there are specific steps that must be taken to minimize space debris generation during the mission lifetime, and actions to safely dispose of the spacecraft at end of mission to prevent it from becoming space debris and a risk to other missions. These steps may involve sacrifices to mission performance and lifetime, but are essential in today's orbital environment.

  17. Space Transportation System Liftoff Debris Mitigation Process Overview

    Science.gov (United States)

    Mitchell, Michael; Riley, Christopher

    2011-01-01

    Liftoff debris is a top risk to the Space Shuttle Vehicle. To manage the Liftoff debris risk, the Space Shuttle Program created a team with in the Propulsion Systems Engineering & Integration Office. The Shutt le Liftoff Debris Team harnesses the Systems Engineering process to i dentify, assess, mitigate, and communicate the Liftoff debris risk. T he Liftoff Debris Team leverages off the technical knowledge and expe rtise of engineering groups across multiple NASA centers to integrate total system solutions. These solutions connect the hardware and ana lyses to identify and characterize debris sources and zones contribut ing to the Liftoff debris risk. The solutions incorporate analyses sp anning: the definition and modeling of natural and induced environmen ts; material characterizations; statistical trending analyses, imager y based trajectory analyses; debris transport analyses, and risk asse ssments. The verification and validation of these analyses are bound by conservative assumptions and anchored by testing and flight data. The Liftoff debris risk mitigation is managed through vigilant collab orative work between the Liftoff Debris Team and Launch Pad Operation s personnel and through the management of requirements, interfaces, r isk documentation, configurations, and technical data. Furthermore, o n day of launch, decision analysis is used to apply the wealth of ana lyses to case specific identified risks. This presentation describes how the Liftoff Debris Team applies Systems Engineering in their proce sses to mitigate risk and improve the safety of the Space Shuttle Veh icle.

  18. Task Flow Modeling in Electronic Business Environments

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available In recent years, internet based commerce has developed as a new paradigm. Many factors such as "at home delivery", easy ordering, and usually lower prices contributed to the success of the e-commerce. However, more recently, companies realized that one of the major factors in having a successful internet based business is the design of a user interface that is in concordance with the users' expectations, which includes both functionality and user friendly features. The func-tionality feature of an e-business interface is one of the most important elements when discussing about a specific internet based business. In our paper, we present methods to model task flows for e-business interfaces. We strengthen our study with the design modeling of a practical scenario that may appear in an on-line commercial environment.

  19. The Influence of an EPS Concrete Buffer Layer Thickness on Debris Dams Impacted by Massive Stones in the Debris Flow

    Directory of Open Access Journals (Sweden)

    Xianbin Yu

    2015-01-01

    Full Text Available The failure of debris dams impacted by the massive stones in a debris flow represents a difficult design problem. Reasonable materials selection and structural design can effectively improve the resistance impact performance of debris dams. Based on the cushioning properties of expanded polystyrene (EPS concrete, EPS concrete as a buffer layer poured on the surface of a rigid debris dam was proposed. A three-dimensional numerical calculation model of an EPS concrete buffer layer/rigid debris dam was established. The single-factor theory revealed change rules for the thickness of the buffer layer concerning the maximal impact force of the rigid debris dam surface through numerical simulation. Moreover, the impact force-time/history curves under different calculation conditions for the rigid debris dam surface were compared. Simulation results showed that the EPS concrete buffer layer can not only effectively extend the impact time of massive stones affecting the debris dam but also reduce the impact force of the rigid debris dam caused by massive stones in the debris flow. The research results provide theoretical guidance for transferring the energy of the massive stone impact, creating a structural design and optimizing debris dams.

  20. Modeling of the Lunar Radiation Environment

    International Nuclear Information System (INIS)

    De Angelis, G.; Badavi, F.F.; Clem, J.M.; Blattnig, S.R.; Clowdsley, M.S.; Nealy, J.E.; Tripathi, R.K.; Wilson, J.W.

    2007-01-01

    In view of manned missions targeted to the Moon, for which radiation exposure is one of the greatest challenges to be tackled, it is of fundamental importance to have available a tool, which allows the determination of the particle flux and spectra at any time and at any point of the lunar surface. With this goal in mind, a new model of the Moon's radiation environment due to Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE) has been developed. Primary particles reach the lunar surface, and are transported all throughout the subsurface layers, with backscattering patterns taken into account. The surface itself has been modeled as regolith and bedrock, with composition taken from the results of the instruments flown on the Apollo missions. Subsurface environments like lava tubes have been considered in the analysis. Particle transport has been performed with both deterministic and Monte Carlo codes with an adaptation for planetary surface geometry. Results are given in terms of fluxes, doses and LET, for most kinds of particles for various kinds of soil and rock chemical compositions

  1. Mistaken identity? Visual similarities of marine debris to natural prey items of sea turtles

    Science.gov (United States)

    2014-01-01

    Background There are two predominant hypotheses as to why animals ingest plastic: 1) they are opportunistic feeders, eating plastic when they encounter it, and 2) they eat plastic because it resembles prey items. To assess which hypothesis is most likely, we created a model sea turtle visual system and used it to analyse debris samples from beach surveys and from necropsied turtles. We investigated colour, contrast, and luminance of the debris items as they would appear to the turtle. We also incorporated measures of texture and translucency to determine which of the two hypotheses is more plausible as a driver of selectivity in green sea turtles. Results Turtles preferred more flexible and translucent items to what was available in the environment, lending support to the hypothesis that they prefer debris that resembles prey, particularly jellyfish. They also ate fewer blue items, suggesting that such items may be less conspicuous against the background of open water where they forage. Conclusions Using visual modelling we determined the characteristics that drive ingestion of marine debris by sea turtles, from the point of view of the turtles themselves. This technique can be utilized to determine debris preferences of other visual predators, and help to more effectively focus management or remediation actions. PMID:24886170

  2. Application of the porous medium heat transfer model of ICARE/CATHARE code against debris bed and 'bundle' experiments

    Energy Technology Data Exchange (ETDEWEB)

    Repetto, G. [CEA Cadarache, Institut de Radioprotection et de Surete Nucleaire, DPAM, 13 - Saint-Paul-lez-Durance (France); Ederli, St. [Ente per le Nuove Technologie, l' Energia e l' Ambiente (ENEA) (Italy)

    2007-07-01

    ICARE/CATHARE code is developed by the 'Institut de Radioprotection et de Surete Nucleaire' to simulate Nuclear Reactor behaviour during the course of a Loss of Cooling accident up to the core melting. The assessment of the heat transfer model in porous medium has been performed against experiments performed in ACRR (SNL-USA) and in Phebus reactors (at Cadarache - France). Calculation versus experiment results indicate a good agreement for the thermal behaviour. The heat transfers inside solid debris bed can be well predicted using the Imura-Yagi correlation to calculate the debris bed equivalent thermal conductivity in a wide range of particles size. In the case of 'Rod like geometry' calculations, the fuel rod assembly was modelled assuming several rings of fuel rods, with heat transfer including radiative phenomena using view factors between rods. An alternative modelling has been used considering the fuel rods as a porous medium with with pure UO{sub 2} spherical particles of 1 cm diameter and a total porosity representative of the fuel bundle inside a cylindrical shroud. With this approach (heat exchanges accounted for with the Imura-Yagi correlation), the radial gradient calculated in a small bundle was significantly increased, from a few degrees (with the previous modelling) to about 150/200 K at 2273 K. This modelling has been recently improved, to account for the heat transfer inside a fuel rod bundle, by a specific model based on an electrical analogy, considering the porous medium as a cluster of true cylinders. (authors)

  3. Marine debris removal: one year of effort by the Georgia Sea Turtle-Center-Marine Debris Initiative.

    Science.gov (United States)

    Martin, Jeannie Miller

    2013-09-15

    Once in the marine environment, debris poses a significant threat to marine life that can be prevented through the help of citizen science. Marine debris is any manufactured item that enters the ocean regardless of source, commonly plastics, metal, wood, glass, foam, cloth, or rubber. Citizen science is an effective way to engage volunteers in conservation initiatives and provide education and skill development. The Georgia Sea Turtle Center Marine Debris Initiative (GSTC-MDI) is a grant funded program developed to engage citizens in the removal of marine debris from the beaches of Jekyll Island, GA, USA and the surrounding areas. During the first year of effort, more than 200 volunteers donated over 460 h of service to the removal of marine debris. Of the debris removed, approximately 89% were plastics, with a significant portion being cigarette materials. Given the successful first year, the GSTC-MDI was funded again for a second year. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Observations and modeling of debris and shrapnel impacts on optics and diagnostics at the National Ignition Facility

    Directory of Open Access Journals (Sweden)

    Eder D.

    2013-11-01

    Full Text Available A wide range of targets with laser energies spanning two orders of magnitude have been shot at the National Ignition Facility (NIF. The National Ignition Campaign (NIC targets are cryogenic with Si supports and cooling rings attached to an Al Thermo-Mechanical Package (TMP with a thin (30 micron Au hohlraum inside. Particular attention is placed on the low-energy shots where the TMP is not completely vaporized. In addition to NIC targets, a range of other targets has also been fielded on NIF. For all targets, simulations play a critical role in determining if the risks associated with debris and shrapnel are acceptable. In a number of cases, experiments were redesigned, based on simulations, to reduce risks or to obtain data. The majority of these simulations were done using the ALE-AMR code, which provides efficient late-time (100 – 1000 X the pulse duration 3 D calculations of complex NIF targets.

  5. Model alloy oxidation in oxyfuel characteristic environment

    International Nuclear Information System (INIS)

    Coelho, D.; Rizzo, F.; Kranzmann, A.; Monteiro, M.; Caminha, I.

    2014-01-01

    In the oxyfuel process, pure oxygen is burned in boilers with recycled gas producing a gas rich in CO 2 , making it easer to capture the CO 2 in the end of the process. The present work investigates the high temperature corrosion characteristics of a model Fe-Cr-Co alloy in typical oxyfuel process environment. Samples were oxidized at 600°C during 1000 hours in single atmosphere condition, where the samples is exposed to the same gas in all faces, and in a dual atmosphere condition, where the sample is exposed to water vapor in one side and to oxyfuel gas in the other. Samples where characterized by SEM and EDX. Results showed that corrosion is higher in a dual atmosphere condition than in single condition. (author)

  6. Spectral measurements of returned spacecraft surfaces and the implications for space debris material measurements

    Science.gov (United States)

    Jorgensen, K.; Culp, R. D.; Clark, R. N.

    2001-10-01

    Knowledge of the physical properties of orbital debris is necessary for modeling the debris environment. Current methods determine the size and mass of orbital debris based on knowledge or assumption of the material type of the piece. By using spectroscopy, one can determine the material type of the piece by comparing the absorption features of its spectra to that of lab spectra for given materials. The goal of this research is not to improve the models themselves, but to improve the information others use to make the models. In order to determine the effects of the space environment on the reflectance spectra of spacecraft materials, researchers measured materials from returned spacecraft. Measurements of material degradation for returned missions from the Long Duration Exposure Facility (LDEF) are documented herein. When the spectra of returned spacecraft materials were compared with the pre-flight laboratory spectra degradation in the samples were seen mostly in the visible wavelengths, while the samples showed similar features in the near-infrared. Overall, the results displayed less degradation on the spaceflight samples than anticipated. The spectral measurements of returned spacecraft materials lent credence to continuing the study of determining the material type of orbital debris using spectroscopy.

  7. Plastic Debris Is a Human Health Issue

    NARCIS (Netherlands)

    Vethaak, A.D.; Leslie, H.A.

    2016-01-01

    The global threat of highly persistent plastic waste accumulating and fragmenting in the world’s oceans, inland waters and terrestrial environments is becoming increasingly evident.1−3 Humans are being exposed to both plastic particles and chemical additives being released from the plastic debris of

  8. Meteoroid Environment Modeling: the Meteoroid Engineering Model and Shower Forecasting

    Science.gov (United States)

    Moorhead, Althea V.

    2017-01-01

    The meteoroid environment is often divided conceptually into meteor showers plus a sporadic background component. The sporadic complex poses the bulk of the risk to spacecraft, but showers can produce significant short-term enhancements of the meteoroid flux. The Meteoroid Environment Office (MEO) has produced two environment models to handle these cases: the Meteoroid Engineering Model (MEM) and an annual meteor shower forecast. Both MEM and the forecast are used by multiple manned spaceflight projects in their meteoroid risk evaluation, and both tools are being revised to incorporate recent meteor velocity, density, and timing measurements. MEM describes the sporadic meteoroid complex and calculates the flux, speed, and directionality of the meteoroid environment relative to a user-supplied spacecraft trajectory, taking the spacecraft's motion into account. MEM is valid in the inner solar system and offers near-Earth and cis-lunar environments. While the current version of MEM offers a nominal meteoroid environment corresponding to a single meteoroid bulk density, the next version of MEMR3 will offer both flux uncertainties and a density distribution in addition to a revised near-Earth environment. We have updated the near-Earth meteor speed distribution and have made the first determination of uncertainty in this distribution. We have also derived a meteor density distribution from the work of Kikwaya et al. (2011). The annual meteor shower forecast takes the form of a report and data tables that can be used in conjunction with an existing MEM assessment. Fluxes are typically quoted to a constant limiting kinetic energy in order to comport with commonly used ballistic limit equations. For the 2017 annual forecast, the MEO substantially revised the list of showers and their characteristics using 14 years of meteor flux measurements from the Canadian Meteor Orbit Radar (CMOR). Defunct or insignificant showers were removed and the temporal profiles of many showers

  9. Debris disc constraints on planetesimal formation

    Science.gov (United States)

    Krivov, Alexander V.; Ide, Aljoscha; Löhne, Torsten; Johansen, Anders; Blum, Jürgen

    2018-02-01

    Two basic routes for planetesimal formation have been proposed over the last decades. One is a classical `slow-growth' scenario. Another one is particle concentration models, in which small pebbles are concentrated locally and then collapse gravitationally to form planetesimals. Both types of models make certain predictions for the size spectrum and internal structure of newly born planetesimals. We use these predictions as input to simulate collisional evolution of debris discs left after the gas dispersal. The debris disc emission as a function of a system's age computed in these simulations is compared with several Spitzer and Herschel debris disc surveys around A-type stars. We confirm that the observed brightness evolution for the majority of discs can be reproduced by classical models. Further, we find that it is equally consistent with the size distribution of planetesimals predicted by particle concentration models - provided the objects are loosely bound `pebble piles' as these models also predict. Regardless of the assumed planetesimal formation mechanism, explaining the brightest debris discs in the samples uncovers a `disc mass problem'. To reproduce such discs by collisional simulations, a total mass of planetesimals of up to ˜1000 Earth masses is required, which exceeds the total mass of solids available in the protoplanetary progenitors of debris discs. This may indicate that stirring was delayed in some of the bright discs, that giant impacts occurred recently in some of them, that some systems may be younger than previously thought or that non-collisional processes contribute significantly to the dust production.

  10. Building Information Modelling for Smart Built Environments

    Directory of Open Access Journals (Sweden)

    Jianchao Zhang

    2015-01-01

    Full Text Available Building information modelling (BIM provides architectural 3D visualization and a standardized way to share and exchange building information. Recently, there has been an increasing interest in using BIM, not only for design and construction, but also the post-construction management of the built facility. With the emergence of smart built environment (SBE technology, which embeds most spaces with smart objects to enhance the building’s efficiency, security and comfort of its occupants, there is a need to understand and address the challenges BIM faces in the design, construction and management of future smart buildings. In this paper, we investigate how BIM can contribute to the development of SBE. Since BIM is designed to host information of the building throughout its life cycle, our investigation has covered phases from architecture design to facility management. Firstly, we extend BIM for the design phase to provide material/device profiling and the information exchange interface for various smart objects. Next, we propose a three-layer verification framework to assist BIM users in identifying possible defects in their SBE design. For the post-construction phase, we have designed a facility management tool to provide advanced energy management of smart grid-connected SBEs, where smart objects, as well as distributed energy resources (DERs are deployed.

  11. Disaster Debris Recovery Database - Landfills

    Data.gov (United States)

    U.S. Environmental Protection Agency — The US EPA Disaster Debris Recovery Database (DDRD) promotes the proper recovery, recycling, and disposal of disaster debris for emergency responders at the federal,...

  12. Disaster Debris Recovery Database - Recovery

    Data.gov (United States)

    U.S. Environmental Protection Agency — The US EPA Disaster Debris Recovery Database (DDRD) promotes the proper recovery, recycling, and disposal of disaster debris for emergency responders at the federal,...

  13. Unimodal models to relate species to environment

    NARCIS (Netherlands)

    Braak, ter C.J.F.

    1987-01-01

    To assess the impact of environmental change on biological communities knowledge about species-environment relationships is indispensable. Ecologists attempt to uncover the relationships between species and environment from data obtained from field surveys. In the survey, species are scored on their

  14. Group Modeling in Social Learning Environments

    Science.gov (United States)

    Stankov, Slavomir; Glavinic, Vlado; Krpan, Divna

    2012-01-01

    Students' collaboration while learning could provide better learning environments. Collaboration assumes social interactions which occur in student groups. Social theories emphasize positive influence of such interactions on learning. In order to create an appropriate learning environment that enables social interactions, it is important to…

  15. Enhanced living environments from models to technologies

    CERN Document Server

    Dobre, Ciprian; Ganchev, Ivan; Garcia, Nuno; Goleva, Rossitza Ivanova

    2017-01-01

    Enhanced living environments employ information and communications technologies to support true ambient assisted living for people with disabilities. This book provides an overview of today's architectures, techniques, protocols, components, and cloud-based solutions related to ambient assisted living and enhanced living environments.

  16. Building, Using, Sharing and Reusing Environment Concept Models

    National Research Council Canada - National Science Library

    Chadbourne, Christopher; Clark, Douglas

    2006-01-01

    .... The Environment Concept Model (ECM) is an object-oriented documentation technique. The technique is tailored for system engineers who must deliver a consistent synthetic environment representation, on time and within budget...

  17. Styrofoam debris as a potential carrier of mercury within ecosystems.

    Science.gov (United States)

    Graca, Bożena; Bełdowska, Magdalena; Wrzesień, Patrycja; Zgrundo, Aleksandra

    2014-02-01

    The present paper falls within the trend of research into interactions between various pollutants emitted anthropogenically into the environment and focuses on mercury and styrofoam debris. The study covers part of the Southern Baltic's drainage area. Apart from styrofoam and beach sand, the research involved mosses, which are bioindicators of atmospheric metal pollution. The research has shown that mercury present in the environment becomes associated with styrofoam debris. The median for mercury concentrations in virgin styrofoam samples (0.23 ng g(-1) dry weight (d.w.)) and in beach sand samples (0.69 ng g(-1) d.w.) was an order of magnitude lower than in the styrofoam debris (5.20 ng g(-1) d.w.). The highest mercury content observed in styrofoam debris (3,863 ng g(-1) d.w.) exceeded the standards for bottom sediment and soil. The binding of mercury to styrofoam debris takes place in water, and presumably also through contact with the ground. A significant role in this process was played by biotic factors, such as the presence of biofilm and abiotic ones, such as solar radiation and the transformations of mercury forms related to it. As a result, mercury content in styrofoam debris underwent seasonal changes, peaking in summertime. Furthermore, the regional changes of mercury content in the studied debris seem to reflect the pollution levels of the environment.

  18. Final payload test results for the RemoveDebris active debris removal mission

    Science.gov (United States)

    Forshaw, Jason L.; Aglietti, Guglielmo S.; Salmon, Thierry; Retat, Ingo; Roe, Mark; Burgess, Christopher; Chabot, Thomas; Pisseloup, Aurélien; Phipps, Andy; Bernal, Cesar; Chaumette, François; Pollini, Alexandre; Steyn, Willem H.

    2017-09-01

    Since the beginning of the space era, a significant amount of debris has progressively been generated in space. Active Debris Removal (ADR) missions have been suggested as a way of limiting and controlling future growth in orbital space debris by actively deploying vehicles to remove debris. The European Commission FP7-sponsored RemoveDebris mission, which started in 2013, draws on the expertise of some of Europe's most prominent space institutions in order to demonstrate key ADR technologies in a cost effective ambitious manner: net capture, harpoon capture, vision-based navigation, dragsail de-orbiting. This paper provides an overview of some of the final payload test results before launch. A comprehensive test campaign is underway on both payloads and platform. The tests aim to demonstrate both functional success of the experiments and that the experiments can survive the space environment. Space environmental tests (EVT) include vibration, thermal, vacuum or thermal-vacuum (TVAC) and in some cases EMC and shock. The test flow differs for each payload and depends on the heritage of the constituent payload parts. The paper will also provide an update to the launch, expected in 2017 from the International Space Station (ISS), and test philosophy that has been influenced from the launch and prerequisite NASA safety review for the mission. The RemoveDebris mission aims to be one of the world's first in-orbit demonstrations of key technologies for active debris removal and is a vital prerequisite to achieving the ultimate goal of a cleaner Earth orbital environment.

  19. Modeling Based Decision Support Environment, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Phoenix Integration's vision is the creation of an intuitive human-in-the-loop engineering environment called Decision Navigator that leverages recent advances in...

  20. Thoughts About Created Environment: A Neuman Systems Model Concept.

    Science.gov (United States)

    Verberk, Frans; Fawcett, Jacqueline

    2017-04-01

    This essay is about the Neuman systems model concept of the created environment. The essay, based on work by Frans Verberk, a Neuman systems model scholar from the Netherlands, extends understanding of the created environment by explaining how this distinctive perspective of environment represents an elaboration of the physiological, psychological, sociocultural, developmental, and spiritual variables, which are other central concepts of the Neuman Systems Model.

  1. Model of Conservation on Sagara Anakan Environment

    Directory of Open Access Journals (Sweden)

    Dede Sugandi

    2013-12-01

    Full Text Available Widespread decline in agricultural land and the impact on production decline caused extensive forest activities to meet the needs of the population. Activities that cause less environmental quality offset environmental balance changes. These changes due to deforestation, erosion, degraded land and natural resource degradation are exploited so that the function of ecological, economic and social life. Damaged ecosystems resulting in erosion, landslides in the watershed affect the sedimentation in Sagara Anakan sea. Silting, resulting in narrowing of fishing activities, tourism, sports, and services decreased crossings. Because of the problem and the purpose of this study proposed and analyzed a few questions: 1 How does the socio-economic impact of farmers in conserving the environment of Sagara Anakan ?, 2 How do people form of conservation and coastal of Sagara Anakan ?, 3 How model of integrated conservation in the watershed and coastal of Sagara Anakan ? and 4 What role do the people in the watershed and coastal on Sagara Anakan conservation ?. Study site covers an area of flow and Ci Ci Tanduy Beureum and Sagara Tillers waters. Activities of the population in the process of land affected when in Sagara tillers. The method used was a survey with a sample divided by the watershed upstream, downstream and coastal tengahm. Using statistical analysis techniques and geography, so that part of the watershed characteristics can be imaged. Shallowing Sagara Anakan, physically was affected by the physical condition of the easily eroded and accelerated by human activities. The activities of farmer on the watershed have done conservation unless doing reforestation, whereas the farmer on the swamp and coastal areas are not doing conservation. Different physical circumstances, the conservation of watersheds and coastal forms differ. Socio-economic condition of farmer affect the conservation. The farmer could not reforestation conservation form, as the

  2. Plastic Debris Occurrence, Convergence Areas and Fin Whales Feeding Ground in the Mediterranean Marine Protected Area Pelagos Sanctuary: A Modeling Approach

    Directory of Open Access Journals (Sweden)

    Maria Cristina Fossi

    2017-05-01

    Full Text Available The Mediterranean Sea is greatly affected by marine litter. In this area, research on the impact of plastic debris (including microplastics on biota, particularly large filter-feeding species such as the fin whale (Balaenoptera physalus, is still in its infancy. We investigated the possible overlap between microplastic, mesoplastic and macrolitter accumulation areas and the fin whale feeding grounds in in a pelagic Specially Protected Area of Mediterranean Importance (SPAMI: the Pelagos Sanctuary. Models of ocean circulation and fin whale potential habitat were merged to compare marine litter accumulation with the presence of whales. Additionally, field data on microplastics, mesoplastics, and macrolitter abundance and cetacean presence were simultaneously collected. The resulting data were compared, as a multi-layer, with the simulated distribution of plastic concentration and the whale habitat model. These data showed a high occurrence of microplastics (mean: 0.082 items/m2, STD ± 0.079 items/m2 spatial distribution agreed with our modeling results. Areas with high microplastic density significantly overlapped with areas of high macroplastic density. The most abundant polymer detected in all the sampling sites was polyethylene (PE, suggesting fragmentation of larger packaging items as the primary source. To our knowledge, this is the first study in the Pelagos Sanctuary in which the simulated microplastic distribution has been confirmed by field observations. The overlap between the fin whale feeding habitat and the microplastic hot spots is an important contribution for risk assessment of fin whale exposure to microplastics.

  3. Propagation modeling in a manufacturing environment

    Energy Technology Data Exchange (ETDEWEB)

    Birdwell, J.D.; Horn, R.D.; Rader, M.S. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Electrical Engineering; Shourbaji, A.A. [Oak Ridge Centers for Mfg. Technology, TN (United States)

    1995-12-31

    Wireless sensors which utilize low power spread spectrum data transmission have significant potential in industrial environments due to low cabling and installation costs. In addition, this technology imposes fewer constraints upon placement due to cable routing, allowing sensors to be installed in areas with poor access. Limitations are imposed on sensor and receiver placement by electromagnetic propagation effects in the industrial environment, including multipath and the presence of absorbing media. This paper explores the electromagnetic analysis of potential wireless sensor applications using commercially available finite element software. In addition, since the applications environment is often at least partially specified in electronic form using computer-aided drafting software, the importation of information from this software is discussed. Both three-dimensional and two-dimensional examples are presented which demonstrate the utility and limitations of the method.

  4. Cost-effective and robust mitigation of space debris in low earth orbit

    Science.gov (United States)

    Walker, R.; Martin, C. E.

    2004-01-01

    For the wide acceptance of space debris mitigation measures throughout government agencies and industry, their cost-effectiveness must be demonstrated. The selected measures must not only be effective at controlling the future growth of the debris population, but they should also aim to minimise the collision risk to spacecraft at a minimal cost of implementation. Furthermore, the selected measures must be sufficiently robust to retain their effectiveness if unexpected increases in space activity were to occur. In this paper, clear criteria are established in order to assess numerous different Low Earth Orbit (LEO) debris mitigation scenarios for their cost-effectiveness and robustness. The ESA DELTA debris model is used to provide long-term debris environment projections for these scenarios as an input to the effectiveness/robustness element. Manoeuvre requirements for the different post-mission disposal scenarios are calculated in order to define the cost-related element. A 25-year post-mission lifetime de-orbit policy, combined with explosion prevention and mission-related object limitation, was found to be the most cost-effective solution to the space debris problem in LEO. This package would also be robust enough to retain its effectiveness even after a significant increase in future launch traffic. It was found that the re-orbiting of space systems above the LEO region would not lead to significant collision activity there over the next century. However, above-LEO disposal should be used sparingly because the disposal region could become unstable after a limited number of localised explosion or collision-induced breakup events due to a lack of air drag to remove the resulting fragments.

  5. Occupant modeling in the aerospace environment

    NARCIS (Netherlands)

    Yaklin, P.; Lim, T.; Marshall, R.

    1999-01-01

    Dynamic testing and occupant protection standards are a reality in the aerospace industry. Methods to model these situations are evolving. A method of modeling an occupant on a crew seat, in a drop test is presented. This method combines a rigid body occupant model with a finite element model of the

  6. Ice Cliff Backwasting over debris-covered Glaciers - Insights into their Formation and Development based on new Measurements and a point-scale Model

    Science.gov (United States)

    Steiner, J. F.; Pellicciotti, F.; Buri, P.; Miles, E. S.; Reid, T. D.; Immerzeel, W.

    2014-12-01

    The presence of ice cliffs has been identified as one possible reason for relatively high overall ablation rates on debris covered glaciers. Few measurements exist for such cliffs and their formation and evolution processes are still poorly understood. On Lirung Glacier, in the Nepalese Himalayas, numerous cliffs were monitored for two consecutive years in the pre- and post-monsoon season. Slope varied between 30° and full vertical faces. Backwasting rates were highly variable depending on slope and aspect of the location on the cliff. Only a physically based energy balance model can reproduce this heterogeneity and provide insights into the importance of atmospheric forcing and cliff characteristics on their melt. Building on two previous studies such a model was developed. It was improved with measurements of radiative fluxes perpendicular to the cliff and by applying a high resolution DEM of the surrounding topography to estimate shading and radiative fluxes incident to the cliff including longwave radiation emitted by surrounding debris. We obtain a considerable reduction in incoming shortwave radiation for north-oriented cliffs compared to horizontal measurements, and significant incident longwave component that varies with height on the cliffs. Melt rates are highly variable in time and space for the cliff. While maximum values of up to 8 cm/day are reached during monsoon, melt rates in the post-monsoon season are considerably lower than in the pre-monsoon season. Nighttime refreezing processes during this period also played an important role. Apart from topography, cliff backwasting is extremely sensitive to albedo of the ice surface, reaching values as low as 0.05. Measurements of surface temperature and wind on the cliff further improved the understanding of outgoing radiation and turbulent fluxes. Once validated against stakes readings, the model was used to explain the presence and persistence of cliffs over Lirung glacier. We show that only North

  7. Patterns In Debris Disks: No Planets Required?

    Science.gov (United States)

    Kuchner, Marc

    2012-01-01

    Debris disks like those around Fomalhaut and Beta Pictoris show striking dust patterns often attributed to hidden exoplanets. These patterns have been crucial for constraining the masses and orbits of these planets. But adding a bit of gas to our models of debris disks--too little gas to detect--seems to alter this interpretation. Small amounts of gas lead to new dynamical instabilities that may mimic the narrow eccentric rings and other structures planets would create in a gas-free disk. Can we still use dust patterns to find hidden exoplanets?

  8. Mars Environment and Magnetic Orbiter model payload

    DEFF Research Database (Denmark)

    Langlais, B.; Leblanc, F.; Fouchet, T.

    2009-01-01

    Mars Environment and Magnetic Orbiter was proposed as an answer to the Cosmic Vision Call of Opportunity as a M-class mission. The MEMO mission is designed to study the strong interconnections between the planetary interior, atmosphere and solar conditions essential to understand planetary...

  9. A Collaborative Model for Ubiquitous Learning Environments

    Science.gov (United States)

    Barbosa, Jorge; Barbosa, Debora; Rabello, Solon

    2016-01-01

    Use of mobile devices and widespread adoption of wireless networks have enabled the emergence of Ubiquitous Computing. Application of this technology to improving education strategies gave rise to Ubiquitous e-Learning, also known as Ubiquitous Learning. There are several approaches to organizing ubiquitous learning environments, but most of them…

  10. Orbital Debris: Past, Present, and Future

    Science.gov (United States)

    Stansbery, Gene; Johnson, Nicholas

    2013-01-01

    In the early days of spaceflight, the gBig Sky h theory was the near universally accepted paradigm for dealing with collisions of orbiting objects. This theory was also used during the early years of the aviation industry. Just as it did in aviation, the gBig Sky h theory breaks down as more and more objects accumulate in the environment. Fortunately, by the late 1970 fs some visionaries in NASA and the US Department of Defense (DoD) realized that trends in the orbital environment would inevitably lead to increased risks to operational spacecraft from collisions with other orbiting objects. The NASA Orbital Debris Program was established at and has been conducted at Johnson Space Center since 1979. At the start of 1979, fewer than 5000 objects were being tracked by the US Space Surveillance Network and very few attempts had been made to sample the environment for smaller sizes. Today, the number of tracked objects has quadrupled. Ground ]based and in situ measurements have statistically sampled the LEO environment over most sizes and mitigation guidelines and requirements are common among most space faring nations. NASA has been a leader, not only in defining the debris environment, but in promoting awareness of the issues in the US and internationally, and in providing leadership in developing policies to address the issue. This paper will discuss in broad terms the evolution of the NASA debris program from its beginnings to its present broad range of debris related research. The paper will discuss in some detail current research topics and will attempt to predict future research trends.

  11. Rapid Debris Analysis Project Task 3 Final Report - Sensitivity of Fallout to Source Parameters, Near-Detonation Environment Material Properties, Topography, and Meteorology

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, Peter [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-01-24

    This report describes the sensitivity of predicted nuclear fallout to a variety of model input parameters, including yield, height of burst, particle and activity size distribution parameters, wind speed, wind direction, topography, and precipitation. We investigate sensitivity over a wide but plausible range of model input parameters. In addition, we investigate a specific example with a relatively narrow range to illustrate the potential for evaluating uncertainties in predictions when there are more precise constraints on model parameters.

  12. A Numerical Study on the Effect of Debris Layer on Fretting Wear

    Directory of Open Access Journals (Sweden)

    Tongyan Yue

    2016-07-01

    Full Text Available Fretting wear is the material damage of two contact surfaces caused by micro relative displacement. Its characteristic is that debris is trapped on the contact surfaces. Depending on the material properties, the shapes of the debris, and the dominant wear mechanisms, debris can play different roles that either protect or harm interfaces. Due to the micro scale of the debris, it is difficult to obtain instantaneous information and investigate debris behavior in experiments. The Finite Element Method (FEM has been used to model the process of fretting wear and calculate contact variables, such as contact stress and relative slip during the fretting wear process. In this research, a 2D fretting wear model with a debris layer was developed to investigate the influence of debris on fretting wear. Effects of different factors such as thickness of the debris layer, Young’s modulus of the debris layer, and the time of importing the layer into the FE model were considered in this study. Based on FE results, here we report that: (a the effect of Young’s modulus of the debris layer on the contact pressure is not significant; (b the contact pressure between the debris layer and the flat specimen decreases with increasing thickness of the layer and (c by importing the debris layer in different fretting wear cycles, the debris layer shows different roles in the wear process. At the beginning of the wear cycle, the debris layer protects the contact surfaces of the first bodies (cylindrical pad and flat specimen. However, in the final cycle, the wear volumes of the debris layers exhibit slightly higher damage compared to the model without the debris layer in all considered cases.

  13. Frequency and initiation of debris flows in Grand Canyon, Arizona

    Science.gov (United States)

    Griffiths, Peter G.; Webb, Robert H.; Melis, Theodore S.

    2004-12-01

    Debris flows from 740 tributaries transport sediment into the Colorado River in Grand Canyon, Arizona, creating rapids that control its longitudinal profile. Debris flows mostly occur when runoff triggers failures in colluvium by a process termed "the fire hose effect." Debris flows originate from a limited number of geologic strata, almost exclusively shales or other clay-rich, fine-grained formations. Observations from 1984 through 2003 provide a 20 year record of all debris flows that reached the Colorado River in Grand Canyon, and repeat photography provides a 100 year record of debris flows from 147 tributaries. Observed frequencies are 5.1 events/year from 1984 to 2003, and historic frequencies are 5.0 events/year from 1890 to 1983. Logistic regression is used to model historic frequencies based on drainage basin parameters observed to control debris flow initiation and transport. From 5 to 7 of the 16 parameters evaluated are statistically significant, including drainage area, basin relief, and the height of and gradient below debris flow source areas, variables which reflect transport distance and potential energy. The aspect of the river channel, which at least partially reflects storm movement within the canyon, is also significant. Model results are used to calculate the probability of debris flow occurrence at the river over a century for all 740 tributaries. Owing to the variability of underlying geomorphic controls, the distribution of this probability is not uniform among tributaries of the Colorado River in Grand Canyon.

  14. Anthropogenic effect on avalanche and debris flow activity

    Directory of Open Access Journals (Sweden)

    S. A. Sokratov

    2013-01-01

    Full Text Available The paper presents examples of the change in snow avalanches and debris flows activity due to the anthropogenic pressure on vegetation and relief. The changes in dynamical characteristics of selected snow avalanches and debris flows due to the anthropogenic activity are quantified. The conclusion is made that the anthropogenic effects on the snow avalanches and debris flows activity are more pronounced than the possible effects of the climate change. The necessity is expressed on the unavoidable changes of the natural environment as the result of a construction and of use of the constructed infrastructure to be account for in corresponding planning of the protection measures.

  15. A comparative analysis of reactor lower head debris cooling models employed in the existing severe accident analysis codes

    International Nuclear Information System (INIS)

    Ahn, K.I.; Kim, D.H.; Kim, S.B.; Kim, H.D.

    1998-08-01

    MELCOR and MAAP4 are the representative severe accident analysis codes which have been developed for the integral analysis of the phenomenological reactor lower head corium cooling behavior. Main objectives of the present study is to identify merits and disadvantages of each relevant model through the comparative analysis of the lower plenum corium cooling models employed in these two codes. The final results will be utilized for the development of LILAC phenomenological models and for the continuous improvement of the existing MELCOR reactor lower head models, which are currently being performed at the KAERI. For these purposes, first, nine reference models are selected featuring the lower head corium behavior based on the existing experimental evidences and related models. Then main features of the selected models have been critically analyzed, and finally merits and disadvantages of each corresponding model have been summarized in the view point of realistic corium behavior and reasonable modeling. Being on these evidences, summarized and presented the potential improvements for developing more advanced models. The present study has been focused on the qualitative comparison of each model and so more detailed quantitative analysis is strongly required to obtain the final conclusions for their merits and disadvantages. In addition, in order to compensate the limitations of the current model, required further studies relating closely the detailed mechanistic models with the molten material movement and heat transfer based on phase-change in the porous medium, to the existing simple models. (author). 36 refs

  16. Space debris- ECSL Study

    Science.gov (United States)

    Lafferranderie, G.

    2002-01-01

    Despite several attempts and despite the worldwide recognition of the need of attacking it, the space debris legal issues has not been put in the agenda as a separate issue on the agenda of the COPUOS Legal Subcommittee. However for the first time, mention will appear in 2002 but only under item 5 of the Legal Subcommittee: report of activities of international organisations, here the European Centre for Space Law (ECSL). ECSL report will describe the method followed, a questionnaire widely distributed to interested persons and on a personal basis. The questionnaire tries to identify the basic concerns. From the responses received and from also analysis of positions expressed in various colloquia, articles, etc. some directions could be drawn up: do we need a "legal definition" of space debris? For which purposes? Are we in a situation fro presenting now such a legal definition able to cope with the technical evolution of the space object? Which type of legal or technical description "instrument" will be the most appropriate? Etc. One particular question is emerging: the basis of the liability for damages caused in outer space. The author wish is simply to draw the attention on concrete, immediate concerns while identifying also simple ways able to offer a framework to deal with the legal impacts coming from space debris issue. I have envisioned two other subjects that I have abandoned: .

  17. A real two-phase submarine debris flow and tsunami

    International Nuclear Information System (INIS)

    Pudasaini, Shiva P.; Miller, Stephen A.

    2012-01-01

    The general two-phase debris flow model proposed by Pudasaini is employed to study subaerial and submarine debris flows, and the tsunami generated by the debris impact at lakes and oceans. The model, which includes three fundamentally new and dominant physical aspects such as enhanced viscous stress, virtual mass, and generalized drag (in addition to buoyancy), constitutes the most generalized two-phase flow model to date. The advantage of this two-phase debris flow model over classical single-phase, or quasi-two-phase models, is that the initial mass can be divided into several parts by appropriately considering the solid volume fraction. These parts include a dry (landslide or rock slide), a fluid (water or muddy water; e.g., dams, rivers), and a general debris mixture material as needed in real flow simulations. This innovative formulation provides an opportunity, within a single framework, to simultaneously simulate the sliding debris (or landslide), the water lake or ocean, the debris impact at the lake or ocean, the tsunami generation and propagation, the mixing and separation between the solid and fluid phases, and the sediment transport and deposition process in the bathymetric surface. Applications of this model include (a) sediment transport on hill slopes, river streams, hydraulic channels (e.g., hydropower dams and plants); lakes, fjords, coastal lines, and aquatic ecology; and (b) submarine debris impact and the rupture of fiber optic, submarine cables and pipelines along the ocean floor, and damage to offshore drilling platforms. Numerical simulations reveal that the dynamics of debris impact induced tsunamis in mountain lakes or oceans are fundamentally different than the tsunami generated by pure rock avalanches and landslides. The analysis includes the generation, amplification and propagation of super tsunami waves and run-ups along coastlines, debris slide and deposition at the bottom floor, and debris shock waves. It is observed that the

  18. The Fabulous Four Debris Disks

    Science.gov (United States)

    Werner, Michael; Stapelfeldt, Karl

    2004-09-01

    This program is a comprehensive study of the four bright debris disks that were spatially resolved by IRAS: Beta Pictoris, Epsilon Eridani, Fomalhaut, and Vega. All SIRTF instruments and observing modes will be used. The program has three major objectives: (1) Study of the disk spatial structure from MIPS and IRAC imaging; (2) Study of the dust grain composition using the IRS and MIPS SED mode; and (3) companion searches using IRAC. The data from this program should lead to a detailed understanding of these four systems, and will provide a foundation for understanding all of the debris disks to be studied with SIRTF. Images and spectra will be compared with models for disk structure and dust properties. Dynamical features indicative of substellar companions' effects on the disks will be searched for. This program will require supporting observations of PSF stars, some of which have been included explicitly. In the majority of cases, the spectral observations require a preferred orientation to align the slits along the disk position angles. Detector saturation issues are still being worked for this program, and will lead to AOR modifications in subsequent submissions. The results from this program will be analyzed collaboratively by the IRAC, IRS, and MIPS teams and by general GTOs Jura and Werner.

  19. LIDT-DD: A new self-consistent debris disc model that includes radiation pressure and couples dynamical and collisional evolution

    Science.gov (United States)

    Kral, Q.; Thébault, P.; Charnoz, S.

    2013-10-01

    Context. In most current debris disc models, the dynamical and the collisional evolutions are studied separately with N-body and statistical codes, respectively, because of stringent computational constraints. In particular, incorporating collisional effects (especially destructive collisions) into an N-body scheme has proven a very arduous task because of the exponential increase of particles it would imply. Aims: We present here LIDT-DD, the first code able to mix both approaches in a fully self-consistent way. Our aim is for it to be generic enough to be applied to any astrophysical case where we expect dynamics and collisions to be deeply interlocked with one another: planets in discs, violent massive breakups, destabilized planetesimal belts, bright exozodiacal discs, etc. Methods: The code takes its basic architecture from the LIDT3D algorithm for protoplanetary discs, but has been strongly modified and updated to handle the very constraining specificities of debris disc physics: high-velocity fragmenting collisions, radiation-pressure affected orbits, absence of gas that never relaxes initial conditions, etc. It has a 3D Lagrangian-Eulerian structure, where grains of a given size at a given location in a disc are grouped into super-particles or tracers whose orbits are evolved with an N-body code and whose mutual collisions are individually tracked and treated using a particle-in-a-box prescription designed to handle fragmenting impacts. To cope with the wide range of possible dynamics for same-sized particles at any given location in the disc, and in order not to lose important dynamical information, tracers are sorted and regrouped into dynamical families depending on their orbits. A complex reassignment routine that searches for redundant tracers in each family and reassignes them where they are needed, prevents the number of tracers from diverging. Results: The LIDT-DD code has been successfully tested on simplified cases for which robust results have

  20. Interoperation Modeling for Intelligent Domotic Environments

    Science.gov (United States)

    Bonino, Dario; Corno, Fulvio

    This paper introduces an ontology-based model for domotic device inter-operation. Starting from a previously published ontology (DogOnt) a refactoring and extension is described allowing to explicitly represent device capabilities, states and commands, and supporting abstract modeling of device inter-operation.

  1. FAME - A Flexible Appearance Modelling Environment

    DEFF Research Database (Denmark)

    Stegmann, Mikkel Bille; Ersbøll, Bjarne Kjær; Larsen, Rasmus

    2003-01-01

    performance and make models generalise better, we apply parallel analysis to obtain automatic and objective model truncation. Further, two different AAM training methods are compared along with a reference case study carried out on cross-sectional short-axis cardiac magnetic resonance images and face images...

  2. Lattice models for invasions through patchy environments.

    Science.gov (United States)

    Campos, Daniel; Méndez, Vicenç; Ortega-Cejas, Vicente

    2008-10-01

    We analyze traveling front solutions for a class of reaction-transport Lattice Models (LMs) in order to claim their interest on the description of biological invasions. As lattice models are spatially discrete models, we address here the problem of invasions trough patchy habitats, where every node in the lattice represents a different patch. Distributed generation times for the individuals are considered, so that different temporal patterns can be studied. Specifically, we explore some examples of seasonal and nonseasonal patterns which may be of ecological interest. The main advantage of the LMs described here is that a direct correspondence between these discrete models and a mesoscopic description of Continuous-Time Random Walks (CTRW) can be found. This point is of great importance, since many times one needs analytical expressions to support or validate numerical results, or vice versa. Finally, that correspondence allows us to provide a discussion about some general aspects of reaction-dispersal models.

  3. Data Acquisition, Management, and Analysis in Support of the Audiology and Hearing Conservation and the Orbital Debris Program Office

    Science.gov (United States)

    Dicken, Todd

    2012-01-01

    My internship at Johnson Space Center, Houston TX comprised of working simultaneously in the Space Life Science Directorate (Clinical Services Branch, SD3) in Audiology and Hearing Conservation and in the Astromaterials Research and Exploration Sciences Directorate in the Orbital Debris Program Office (KX). The purpose of the project done to support the Audiology and Hearing Conservation Clinic (AuHCon) is to organize and analyze auditory test data that has been obtained from tests conducted onboard the International Space Station (ISS) and in Johnson Space Center's clinic. Astronauts undergo a special type of auditory test called an On-Orbit Hearing Assessment (OOHA), which monitors hearing function while crewmembers are exposed to noise and microgravity during long-duration spaceflight. Data needed to be formatted to assist the Audiologist in studying, analyzing and reporting OOHA results from all ISS missions, with comparison to conventional preflight and post-flight audiometric test results of crewmembers. Orbital debris is the #1 threat to manned spacecraft; therefore NASA is investing in different measurement techniques to acquire information on orbital debris. These measurements are taken with telescopes in different parts of the world to acquire brightness variations over time, from which size, rotation rates and material information can be determined for orbital debris. Currently many assumptions are taken to resolve size and material from observed brightness, therefore a laboratory (Optical Measurement Center) is used to simulate the space environment and acquire information of known targets suited to best model the orbital debris population. In the Orbital Debris Program Office (ODPO) telescopic data were acquired and analyzed to better assess the orbital debris population.

  4. On North Pacific circulation and associated marine debris concentration.

    Science.gov (United States)

    Howell, Evan A; Bograd, Steven J; Morishige, Carey; Seki, Michael P; Polovina, Jeffrey J

    2012-01-01

    Marine debris in the oceanic realm is an ecological concern, and many forms of marine debris negatively affect marine life. Previous observations and modeling results suggest that marine debris occurs in greater concentrations within specific regions in the North Pacific Ocean, such as the Subtropical Convergence Zone and eastern and western "Garbage Patches". Here we review the major circulation patterns and oceanographic convergence zones in the North Pacific, and discuss logical mechanisms for regional marine debris concentration, transport, and retention. We also present examples of meso- and large-scale spatial variability in the North Pacific, and discuss their relationship to marine debris concentration. These include mesoscale features such as eddy fields in the Subtropical Frontal Zone and the Kuroshio Extension Recirculation Gyre, and interannual to decadal climate events such as El Niño and the Pacific Decadal Oscillation/North Pacific Gyre Oscillation. Published by Elsevier Ltd.

  5. Semi-automatic recognition of marine debris on beaches.

    Science.gov (United States)

    Ge, Zhenpeng; Shi, Huahong; Mei, Xuefei; Dai, Zhijun; Li, Daoji

    2016-05-09

    An increasing amount of anthropogenic marine debris is pervading the earth's environmental systems, resulting in an enormous threat to living organisms. Additionally, the large amount of marine debris around the world has been investigated mostly through tedious manual methods. Therefore, we propose the use of a new technique, light detection and ranging (LIDAR), for the semi-automatic recognition of marine debris on a beach because of its substantially more efficient role in comparison with other more laborious methods. Our results revealed that LIDAR should be used for the classification of marine debris into plastic, paper, cloth and metal. Additionally, we reconstructed a 3-dimensional model of different types of debris on a beach with a high validity of debris revivification using LIDAR-based individual separation. These findings demonstrate that the availability of this new technique enables detailed observations to be made of debris on a large beach that was previously not possible. It is strongly suggested that LIDAR could be implemented as an appropriate monitoring tool for marine debris by global researchers and governments.

  6. Bayesian Genomic Prediction with Genotype × Environment Interaction Kernel Models

    Science.gov (United States)

    Cuevas, Jaime; Crossa, José; Montesinos-López, Osval A.; Burgueño, Juan; Pérez-Rodríguez, Paulino; de los Campos, Gustavo

    2016-01-01

    The phenomenon of genotype × environment (G × E) interaction in plant breeding decreases selection accuracy, thereby negatively affecting genetic gains. Several genomic prediction models incorporating G × E have been recently developed and used in genomic selection of plant breeding programs. Genomic prediction models for assessing multi-environment G × E interaction are extensions of a single-environment model, and have advantages and limitations. In this study, we propose two multi-environment Bayesian genomic models: the first model considers genetic effects (u) that can be assessed by the Kronecker product of variance–covariance matrices of genetic correlations between environments and genomic kernels through markers under two linear kernel methods, linear (genomic best linear unbiased predictors, GBLUP) and Gaussian (Gaussian kernel, GK). The other model has the same genetic component as the first model (u) plus an extra component, f, that captures random effects between environments that were not captured by the random effects u. We used five CIMMYT data sets (one maize and four wheat) that were previously used in different studies. Results show that models with G × E always have superior prediction ability than single-environment models, and the higher prediction ability of multi-environment models with u and f over the multi-environment model with only u occurred 85% of the time with GBLUP and 45% of the time with GK across the five data sets. The latter result indicated that including the random effect f is still beneficial for increasing prediction ability after adjusting by the random effect u. PMID:27793970

  7. Bayesian Genomic Prediction with Genotype × Environment Interaction Kernel Models

    Directory of Open Access Journals (Sweden)

    Jaime Cuevas

    2017-01-01

    Full Text Available The phenomenon of genotype × environment (G × E interaction in plant breeding decreases selection accuracy, thereby negatively affecting genetic gains. Several genomic prediction models incorporating G × E have been recently developed and used in genomic selection of plant breeding programs. Genomic prediction models for assessing multi-environment G × E interaction are extensions of a single-environment model, and have advantages and limitations. In this study, we propose two multi-environment Bayesian genomic models: the first model considers genetic effects ( u that can be assessed by the Kronecker product of variance–covariance matrices of genetic correlations between environments and genomic kernels through markers under two linear kernel methods, linear (genomic best linear unbiased predictors, GBLUP and Gaussian (Gaussian kernel, GK. The other model has the same genetic component as the first model ( u plus an extra component, f, that captures random effects between environments that were not captured by the random effects u . We used five CIMMYT data sets (one maize and four wheat that were previously used in different studies. Results show that models with G × E always have superior prediction ability than single-environment models, and the higher prediction ability of multi-environment models with u   and   f over the multi-environment model with only u occurred 85% of the time with GBLUP and 45% of the time with GK across the five data sets. The latter result indicated that including the random effect f is still beneficial for increasing prediction ability after adjusting by the random effect u .

  8. Bayesian Genomic Prediction with Genotype × Environment Interaction Kernel Models.

    Science.gov (United States)

    Cuevas, Jaime; Crossa, José; Montesinos-López, Osval A; Burgueño, Juan; Pérez-Rodríguez, Paulino; de Los Campos, Gustavo

    2017-01-05

    The phenomenon of genotype × environment (G × E) interaction in plant breeding decreases selection accuracy, thereby negatively affecting genetic gains. Several genomic prediction models incorporating G × E have been recently developed and used in genomic selection of plant breeding programs. Genomic prediction models for assessing multi-environment G × E interaction are extensions of a single-environment model, and have advantages and limitations. In this study, we propose two multi-environment Bayesian genomic models: the first model considers genetic effects [Formula: see text] that can be assessed by the Kronecker product of variance-covariance matrices of genetic correlations between environments and genomic kernels through markers under two linear kernel methods, linear (genomic best linear unbiased predictors, GBLUP) and Gaussian (Gaussian kernel, GK). The other model has the same genetic component as the first model [Formula: see text] plus an extra component, F: , that captures random effects between environments that were not captured by the random effects [Formula: see text] We used five CIMMYT data sets (one maize and four wheat) that were previously used in different studies. Results show that models with G × E always have superior prediction ability than single-environment models, and the higher prediction ability of multi-environment models with [Formula: see text] over the multi-environment model with only u occurred 85% of the time with GBLUP and 45% of the time with GK across the five data sets. The latter result indicated that including the random effect f is still beneficial for increasing prediction ability after adjusting by the random effect [Formula: see text]. Copyright © 2017 Cuevas et al.

  9. Educational Network Environment: Models and Implementation

    International Nuclear Information System (INIS)

    Zhivitskaya, H.

    2014-01-01

    The presentation is structured as follows: functional model of distance learning; CDS - Content Development System; CMS - Content Management System; Communications: Microsoft Lync Server 2010; LMS - Learning Management System; Contents; Contents: creation tools; Contents: Multimedia content creation

  10. Sources, composition and spatial distribution of marine debris along the Mediterranean coast of Israel.

    Science.gov (United States)

    Pasternak, Galia; Zviely, Dov; Ribic, Christine A; Ariel, Asaf; Spanier, Ehud

    2017-01-30

    Marine debris (litter) is a complex problem that affects human activities and the marine environment worldwide. The Clean Coast Program in Israel has had some success in keeping most of the coasts clean most of the time, but without understanding the mechanisms of accumulation of marine debris on the coasts of Israel. In 2012, we initiated a study to characterize the types of marine debris, its origins and spatial distribution. Nineteen surveys were done from June 2012 to March 2015 on eight beaches that spanned the coast of Israel. Average debris density was 12.1 items per 100m 2 and 90% of the items were plastic. The top debris categories were food wrappers and disposables, plastic bags and cigarette butts. However, there was variation in the top debris categories among the beaches indicating that a flexible approach with multiple options will be important when addressing the marine debris problem. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. The RHIC/AGS Online Model Environment: Design and Overview

    International Nuclear Information System (INIS)

    Satogata, T.; Brown, K.; Pilat, F.; Tafti Alai, A.; Tepikian, S.; Vanzeijtz

    1999-01-01

    An integrated online modeling environment is currently under development for use by AGS and RHIC physicists and commissioners. This environment combines the modeling efforts of both groups in a CDEV[1] client-server design, providing access to expected machine optics and physics parameters based on live and design machine settings. An abstract modeling interface has been designed as a set of adapters[2] around core computational modeling engines such as MAD and UAL/Teapot++[3]. This approach allows us to leverage existing survey, lattice, and magnet infrastructure, as well as easily incorporate new model engine developments. This paper describes the architecture of the RHIC/AGS modeling environment, including the application interface through CDEV and general tools for graphical interaction with the model using Tcl/Tk. Separate papers at this conference address the specifics of implementation and modeling experience for AGS and RHIC

  12. Export of microplastics from land to sea. A modelling approach

    NARCIS (Netherlands)

    Siegfried, Max; Koelmans, A.A.; Besseling, E.; Kroeze, C.

    2017-01-01

    Quantifying the transport of plastic debris from river to sea is crucial for assessing the risks of plastic debris to human health and the environment. We present a global modelling approach to analyse the composition and quantity of point-source microplastic fluxes from European rivers to the sea.

  13. A Propagation Environment Modeling in Foliage

    Directory of Open Access Journals (Sweden)

    Samn SherwoodW

    2010-01-01

    Full Text Available Foliage clutter, which can be very large and mask targets in backscattered signals, is a crucial factor that degrades the performance of target detection, tracking, and recognition. Previous literature has intensively investigated land clutter and sea clutter, whereas foliage clutter is still an open-research area. In this paper, we propose that foliage clutter should be more accurately described by a log-logistic model. On a basis of pragmatic data collected by ultra-wideband (UWB radars, we analyze two different datasets by means of maximum likelihood (ML parameter estimation as well as the root mean square error (RMSE performance. We not only investigate log-logistic model, but also compare it with other popular clutter models, namely, log-normal, Weibull, and Nakagami. It shows that the log-logistic model achieves the smallest standard deviation (STD error in parameter estimation, as well as the best goodness-of-fit and smallest RMSE for both poor and good foliage clutter signals.

  14. A new security model for collaborative environments

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Deborah [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lorch, Markus [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Thompson, Mary [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Perry, Marcia [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2003-06-06

    Prevalent authentication and authorization models for distributed systems provide for the protection of computer systems and resources from unauthorized use. The rules and policies that drive the access decisions in such systems are typically configured up front and require trust establishment before the systems can be used. This approach does not work well for computer software that moderates human-to-human interaction. This work proposes a new model for trust establishment and management in computer systems supporting collaborative work. The model supports the dynamic addition of new users to a collaboration with very little initial trust placed into their identity and supports the incremental building of trust relationships through endorsements from established collaborators. It also recognizes the strength of a users authentication when making trust decisions. By mimicking the way humans build trust naturally the model can support a wide variety of usage scenarios. Its particular strength lies in the support for ad-hoc and dynamic collaborations and the ubiquitous access to a Computer Supported Collaboration Workspace (CSCW) system from locations with varying levels of trust and security.

  15. Wind erosion modelling in a Sahelian environment

    NARCIS (Netherlands)

    Faye-Visser, S.M.; Sterk, G.; Karssenberg, D.

    2005-01-01

    In the Sahel field observations of wind-blown mass transport often show considerable spatial variation related to the spatial variation of the wind erosion controlling parameters, e.g. soil crust and vegetation cover. A model, used to predict spatial variation in wind erosion and deposition is a

  16. Safe disposal and recycling of water disaster debris in pakistan

    International Nuclear Information System (INIS)

    Latif, A.

    2014-01-01

    Depending upon the nature, the disaster may produce large masses of debris. Waste masses from single disaster integrate to larger magnitude annually. This will ultimately causes the extra work load on personnel and reflects the poor existing debris management facilities. Besides, it will take longer time to rehabilitate the debris exaggerated regions. The study focuses on 2 main cases of disaster i.e. earthquake of 2005 and flood of 2010 in Pakistan. Complete analysis involve two stages: the first stage involve development of disaster and disaster debris effects guidance whereas the second stage involves the development of set of criteria to make efficient environment and positive impacts of successful debris managing scheme. Such principles were employed to evaluate efficiency of debris managing scheme for detailed analysis. The discussion of the detailed analysis depicts methodology which assists the disaster managers, planners and researcher to simply multitude of work. Moreover, the disaster and disaster debris influence direction, the effect evaluation criterion and managing criteria have been established having the effect they can be virtually put into service for prospect debris managing scheme, planning and retort. With respect to character and strictness, calamity may make high magnitude of waste. By keeping in view the precedent calamities in the United States (US), concluded that in few situations produced waste masses approximately five to fifteen times more than yearly waste production rate from a single occasion. Same results were revealed by subsequent tsunami of Indian Ocean. Such kind of large masses may effects the existing solid debris management system and human resources. Major disaster yields large masses of debris in few hours or sometimes even in minutes. The volume of disaster debris depends upon the magnitude of trees ball up, indemnity to houses, business, services etc. The disaster remaining may be equally large in metropolitan and non

  17. Micrometeoroid and Orbital Debris Risk Assessment With Bumper 3

    Science.gov (United States)

    Hyde, J.; Bjorkman, M.; Christiansen, E.; Lear, D.

    2017-01-01

    The Bumper 3 computer code is the primary tool used by NASA for micrometeoroid and orbital debris (MMOD) risk analysis. Bumper 3 (and its predecessors) have been used to analyze a variety of manned and unmanned spacecraft. The code uses NASA's latest micrometeoroid (MEM-R2) and orbital debris (ORDEM 3.0) environment definition models and is updated frequently with ballistic limit equations that describe the hypervelocity impact performance of spacecraft materials. The Bumper 3 program uses these inputs along with a finite element representation of spacecraft geometry to provide a deterministic calculation of the expected number of failures. The Bumper 3 software is configuration controlled by the NASA/JSC Hypervelocity Impact Technology (HVIT) Group. This paper will demonstrate MMOD risk assessment techniques with Bumper 3 used by NASA's HVIT Group. The Permanent Multipurpose Module (PMM) was added to the International Space Station in 2011. A Bumper 3 MMOD risk assessment of this module will show techniques used to create the input model and assign the property IDs. The methodology used to optimize the MMOD shielding for minimum mass while still meeting structural penetration requirements will also be demonstrated.

  18. Autonomous classification models in ubiquitous environments

    OpenAIRE

    Abad Arranz, Miguel Angel

    2016-01-01

    Stream-mining approach is defined as a set of cutting-edge techniques designed to process streams of data in real time, in order to extract knowledge. In the particular case of classification, stream-mining has to adapt its behaviour to the volatile underlying data distributions, what has been called concept drift. Moreover, it is important to note that concept drift may lead to situations where predictive models become invalid and have therefore to be updated to represent the actual concepts...

  19. Retail business model transformation in multichannel environment

    OpenAIRE

    Chapagain, B. (Bimala)

    2015-01-01

    Abstract With the advent of internet and e-commerce, the way of carrying out business and transactions has changed to a great extent. Consumers are continuously changing the way they do shopping and this has forced retail business to transform their traditional brick and mortar into adopting multi-channel business models. Retailing is one of the most dynamic and competitive areas of business organization. Effective marketin...

  20. GENERAL SOLUTIONS FOR VISCOPLASTIC DEBRIS FLOW.

    Science.gov (United States)

    Chen, Cheng-lung

    1988-01-01

    Theoretical velocity profile and theoretical pressure and concentration distributions for (steady) uniform debris flow in wide channels are derived from a generalized viscoplastic fluid (GVF) model without imposing R. A. Bagnold's assumption of constant grain concentration. Good agreement between the theoretical velocity profile and the experimental data of Japanese scientists strongly supports the validity of both the GVF model and the proposed method of solution from the model. It is shown that both E. C. Bingham and Bagnold versions (or submodels) of the GVF model can be used to simulate debris flow at the dynamic state. Although Bagnold's dilatant submodel appears to fit the Japanese data better than the Bingham submodel for flow of noncohesive grains, the choice between them is by no means clear-cut.

  1. Model Of Reconfiguration In Component Environments

    OpenAIRE

    Jakub Grzesiak; Łukasz Jędrychowski

    2015-01-01

    The significance of the component-based software and component platforms has increased in the last 20 years. To achieve full flexibility there is a need of reconfiguration process, which allows to change parameters of system without rebuilding or restarting it. In terms of components such a process should be executed with extraordinary care as contracts between components have to be preserved. In this article model of reconfiguration and roles of the components, which are used in the process,...

  2. Point process-based modeling of multiple debris flow landslides using INLA: an application to the 2009 Messina disaster

    KAUST Repository

    Lombardo, Luigi

    2018-02-13

    We develop a stochastic modeling approach based on spatial point processes of log-Gaussian Cox type for a collection of around 5000 landslide events provoked by a precipitation trigger in Sicily, Italy. Through the embedding into a hierarchical Bayesian estimation framework, we can use the integrated nested Laplace approximation methodology to make inference and obtain the posterior estimates of spatially distributed covariate and random effects. Several mapping units are useful to partition a given study area in landslide prediction studies. These units hierarchically subdivide the geographic space from the highest grid-based resolution to the stronger morphodynamic-oriented slope units. Here we integrate both mapping units into a single hierarchical model, by treating the landslide triggering locations as a random point pattern. This approach diverges fundamentally from the unanimously used presence–absence structure for areal units since we focus on modeling the expected landslide count jointly within the two mapping units. Predicting this landslide intensity provides more detailed and complete information as compared to the classically used susceptibility mapping approach based on relative probabilities. To illustrate the model’s versatility, we compute absolute probability maps of landslide occurrences and check their predictive power over space. While the landslide community typically produces spatial predictive models for landslides only in the sense that covariates are spatially distributed, no actual spatial dependence has been explicitly integrated so far. Our novel approach features a spatial latent effect defined at the slope unit level, allowing us to assess the spatial influence that remains unexplained by the covariates in the model. For rainfall-induced landslides in regions where the raingauge network is not sufficient to capture the spatial distribution of the triggering precipitation event, this latent effect provides valuable imaging support

  3. Quantitative Modeling of Human-Environment Interactions in Preindustrial Time

    Science.gov (United States)

    Sommer, Philipp S.; Kaplan, Jed O.

    2017-04-01

    Quantifying human-environment interactions and anthropogenic influences on the environment prior to the Industrial revolution is essential for understanding the current state of the earth system. This is particularly true for the terrestrial biosphere, but marine ecosystems and even climate were likely modified by human activities centuries to millennia ago. Direct observations are however very sparse in space and time, especially as one considers prehistory. Numerical models are therefore essential to produce a continuous picture of human-environment interactions in the past. Agent-based approaches, while widely applied to quantifying human influence on the environment in localized studies, are unsuitable for global spatial domains and Holocene timescales because of computational demands and large parameter uncertainty. Here we outline a new paradigm for the quantitative modeling of human-environment interactions in preindustrial time that is adapted to the global Holocene. Rather than attempting to simulate agency directly, the model is informed by a suite of characteristics describing those things about society that cannot be predicted on the basis of environment, e.g., diet, presence of agriculture, or range of animals exploited. These categorical data are combined with the properties of the physical environment in coupled human-environment model. The model is, at its core, a dynamic global vegetation model with a module for simulating crop growth that is adapted for preindustrial agriculture. This allows us to simulate yield and calories for feeding both humans and their domesticated animals. We couple this basic caloric availability with a simple demographic model to calculate potential population, and, constrained by labor requirements and land limitations, we create scenarios of land use and land cover on a moderate-resolution grid. We further implement a feedback loop where anthropogenic activities lead to changes in the properties of the physical

  4. K-Basins debris removal equipment - test plan

    International Nuclear Information System (INIS)

    Pitkoff, C.C.

    1995-01-01

    An undetermined amount of debris remains in the K-Basins which must be removed. Due to the different types of debris that will be removed, a variety of tools will be required to complete this project. This test plan gives s broad scope of the requirements that will be used for testing equipment for K-Basin debris removal. The equipment tested will be used in a radioactive environment. The equipment tested will be used to retrieve, cut, clean, and package debris from both K West and K East Basins. Testing is typically divided into six primary categories: development testing, acceptance testing, qualification testing, pre-operational testing, operational testing, and production/process testing

  5. Evaluation of Student's Environment by DEA Models

    Directory of Open Access Journals (Sweden)

    F. Moradi

    2016-11-01

    Full Text Available The important question here is, is there real evaluation in educational advance? In other words, if a student has been successful in mathematics or has been unsuccessful in mathematics, is it possible to find the reasons behind his advance or, is it possible to find the reasons behind his advance or weakness? If we want to respond to this significant question, it should be said that factors of educational advance must be divided into 5 main groups. 1-family, 2-teacher, 3- students 4-school and 5-manager of 3 schools It can then be said that a student's score does not just depend on a factor that people have imaged From this, it can be concluded that by using the DEA and SBM models, each student's efficiency must be researched and the factors of the student's strengths and weaknesses must be analyzed.

  6. On the debris-level origins of adhesive wear.

    Science.gov (United States)

    Aghababaei, Ramin; Warner, Derek H; Molinari, Jean-François

    2017-07-25

    Every contacting surface inevitably experiences wear. Predicting the exact amount of material loss due to wear relies on empirical data and cannot be obtained from any physical model. Here, we analyze and quantify wear at the most fundamental level, i.e., wear debris particles. Our simulations show that the asperity junction size dictates the debris volume, revealing the origins of the long-standing hypothesized correlation between the wear volume and the real contact area. No correlation, however, is found between the debris volume and the normal applied force at the debris level. Alternatively, we show that the junction size controls the tangential force and sliding distance such that their product, i.e., the tangential work, is always proportional to the debris volume, with a proportionality constant of 1 over the junction shear strength. This study provides an estimation of the debris volume without any empirical factor, resulting in a wear coefficient of unity at the debris level. Discrepant microscopic and macroscopic wear observations and models are then contextualized on the basis of this understanding. This finding offers a way to characterize the wear volume in atomistic simulations and atomic force microscope wear experiments. It also provides a fundamental basis for predicting the wear coefficient for sliding rough contacts, given the statistics of junction clusters sizes.

  7. Debris flow-induced topographic changes: effects of recurrent debris flow initiation.

    Science.gov (United States)

    Chen, Chien-Yuan; Wang, Qun

    2017-08-12

    Chushui Creek in Shengmu Village, Nantou County, Taiwan, was analyzed for recurrent debris flow using numerical modeling and geographic information system (GIS) spatial analysis. The two-dimensional water flood and mudflow simulation program FLO-2D were used to simulate debris flow induced by rainfall during typhoon Herb in 1996 and Mindulle in 2004. Changes in topographic characteristics after the debris flows were simulated for the initiation of hydrological characteristics, magnitude, and affected area. Changes in topographic characteristics included those in elevation, slope, aspect, stream power index (SPI), topographic wetness index (TWI), and hypsometric curve integral (HI), all of which were analyzed using GIS spatial analysis. The results show that the SPI and peak discharge in the basin increased after a recurrence of debris flow. The TWI was higher in 2003 than in 2004 and indicated higher potential of landslide initiation when the slope of the basin was steeper. The HI revealed that the basin was in its mature stage and was shifting toward the old stage. Numerical simulation demonstrated that the parameters' mean depth, maximum depth, affected area, mean flow rate, maximum flow rate, and peak flow discharge were increased after recurrent debris flow, and peak discharge occurred quickly.

  8. Quench cooling of superheated debris beds in containment during LWR core meltdown accidents

    International Nuclear Information System (INIS)

    Ginsberg, T.; Chen, J.C.

    1984-01-01

    Light water reactor core meltdown accident sequence studies suggest that superheated debris beds may settle on the concrete floor beneath the reactor vessel. A model for the heat transfer processes during quench of superheated debris beds cooled by an overlying pool of water has been presented in a prior paper. This paper discusses the coolability of decay-heated debris beds from the standpoint of their transient quench characteristics. It is shown that even though a debris bed configuration may be coolable from the point of view of steady-state decay heat removal, the quench behavior from an initially elevated temperature may lead to bed melting prior to quench of the debris

  9. Trust Model to Enhance Security and Interoperability of Cloud Environment

    Science.gov (United States)

    Li, Wenjuan; Ping, Lingdi

    Trust is one of the most important means to improve security and enable interoperability of current heterogeneous independent cloud platforms. This paper first analyzed several trust models used in large and distributed environment and then introduced a novel cloud trust model to solve security issues in cross-clouds environment in which cloud customer can choose different providers' services and resources in heterogeneous domains can cooperate. The model is domain-based. It divides one cloud provider's resource nodes into the same domain and sets trust agent. It distinguishes two different roles cloud customer and cloud server and designs different strategies for them. In our model, trust recommendation is treated as one type of cloud services just like computation or storage. The model achieves both identity authentication and behavior authentication. The results of emulation experiments show that the proposed model can efficiently and safely construct trust relationship in cross-clouds environment.

  10. [Watershed water environment pollution models and their applications: a review].

    Science.gov (United States)

    Zhu, Yao; Liang, Zhi-Wei; Li, Wei; Yang, Yi; Yang, Mu-Yi; Mao, Wei; Xu, Han-Li; Wu, Wei-Xiang

    2013-10-01

    Watershed water environment pollution model is the important tool for studying watershed environmental problems. Through the quantitative description of the complicated pollution processes of whole watershed system and its parts, the model can identify the main sources and migration pathways of pollutants, estimate the pollutant loadings, and evaluate their impacts on water environment, providing a basis for watershed planning and management. This paper reviewed the watershed water environment models widely applied at home and abroad, with the focuses on the models of pollutants loading (GWLF and PLOAD), water quality of received water bodies (QUAL2E and WASP), and the watershed models integrated pollutant loadings and water quality (HSPF, SWAT, AGNPS, AnnAGNPS, and SWMM), and introduced the structures, principles, and main characteristics as well as the limitations in practical applications of these models. The other models of water quality (CE-QUAL-W2, EFDC, and AQUATOX) and watershed models (GLEAMS and MIKE SHE) were also briefly introduced. Through the case analysis on the applications of single model and integrated models, the development trend and application prospect of the watershed water environment pollution models were discussed.

  11. Space debris; challenges and solutions

    NARCIS (Netherlands)

    Van Beurden, E.; Prins, C.

    2013-01-01

    Space debris has been a hot topic for the last few decades, ever since the space industry started growing exponentially. Everyone agrees that space debris is a growing problem and the saturation point has almost been reached. With a big risk of a chain reaction, called the Kessler syndrome, billions

  12. Sources and sinks of plastic debris in estuaries: A conceptual model integrating biological, physical and chemical distribution mechanisms.

    Science.gov (United States)

    Vermeiren, Peter; Muñoz, Cynthia C; Ikejima, Kou

    2016-12-15

    Micro- and macroplastic accumulation threatens estuaries worldwide because of the often dense human populations, diverse plastic inputs and high potential for plastic degradation and storage in these ecosystems. Nonetheless, our understanding of plastic sources and sinks remains limited. We designed conceptual models of the local and estuary-wide transport of plastics. We identify processes affecting the position of plastics in the water column; processes related to the mixing of fresh and salt water; and processes resulting from the influences of wind, topography, and organism-plastic interactions. The models identify gaps in the spatial context of plastic-organisms interactions, the chemical behavior of plastics in estuaries, effects of wind on plastic suspension-deposition cycles, and the relative importance of processes affecting the position in the water column. When interpreted in the context of current understanding, sinks with high management potential can be identified. However, source-sink patterns vary among estuary types and with local scale processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Engineered Barrier System: Physical and Chemical Environment Model

    International Nuclear Information System (INIS)

    Jolley, D. M.; Jarek, R.; Mariner, P.

    2004-01-01

    The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports

  14. Animal models of gene-environment interactions in schizophrenia.

    Science.gov (United States)

    Ayhan, Yavuz; Sawa, Akira; Ross, Christopher A; Pletnikov, Mikhail V

    2009-12-07

    The pathogenesis of schizophrenia and related mental illnesses likely involves multiple interactions between susceptibility genes of small effects and environmental factors. Gene-environment interactions occur across different stages of neurodevelopment to produce heterogeneous clinical and pathological manifestations of the disease. The main obstacle for mechanistic studies of gene-environment interplay has been the paucity of appropriate experimental systems for elucidating the molecular pathways that mediate gene-environment interactions relevant to schizophrenia. Recent advances in psychiatric genetics and a plethora of experimental data from animal studies allow us to suggest a new approach to gene-environment interactions in schizophrenia. We propose that animal models based on identified genetic mutations and measurable environment factors will help advance studies of the molecular mechanisms of gene-environment interplay.

  15. Modeling ion induced effects in thin films and coatings for lunar and space environment applications

    Science.gov (United States)

    Taylor, Edward W.; Pirich, Ronald

    2013-09-01

    Protective thin film coatings are important for many near-Earth and interplanetary space systems applications using photonic components, optical elements, solar cells and detector-sensor front surfaces to name but a few environmentally at-risk technologies. The near-Earth and natural space environment consists of known degradation processes induced within these technologies brought about by atomic oxygen, micrometeorite impacts, space debris and dust, solar generated charged particles, Van Allen belt trapped particles, and galactic cosmic radiation. This paper will focus on presenting the results of an investigation based on simulated ion-induced defect-modeling and nuclear irradiation testing of several innovative hybrid-polymeric self-cleaning hydrophobic coatings investigated for application to space photonic components, lunar surface, avionic and terrestrial applications. Data is reported regarding the radiation resistance of several hybrid polymer coatings containing various loadings of nanometer-sized TiO2 fillers for protecting sensors, structures, human and space vehicles from dust contamination found in space and on the Lunar and other planetary surfaces.

  16. Modelling Technology for Building Fire Scene with Virtual Geographic Environment

    Science.gov (United States)

    Song, Y.; Zhao, L.; Wei, M.; Zhang, H.; Liu, W.

    2017-09-01

    Building fire is a risky activity that can lead to disaster and massive destruction. The management and disposal of building fire has always attracted much interest from researchers. Integrated Virtual Geographic Environment (VGE) is a good choice for building fire safety management and emergency decisions, in which a more real and rich fire process can be computed and obtained dynamically, and the results of fire simulations and analyses can be much more accurate as well. To modelling building fire scene with VGE, the application requirements and modelling objective of building fire scene were analysed in this paper. Then, the four core elements of modelling building fire scene (the building space environment, the fire event, the indoor Fire Extinguishing System (FES) and the indoor crowd) were implemented, and the relationship between the elements was discussed also. Finally, with the theory and framework of VGE, the technology of building fire scene system with VGE was designed within the data environment, the model environment, the expression environment, and the collaborative environment as well. The functions and key techniques in each environment are also analysed, which may provide a reference for further development and other research on VGE.

  17. Progress in integrated energy-economy-environment model system development

    International Nuclear Information System (INIS)

    Yasukawa, Shigeru; Mankin, Shuichi; Sato, Osamu; Tadokoro, Yoshihiro; Nakano, Yasuyuki; Nagano, Takao

    1987-11-01

    The Integrated Energy-Economy-Environment Model System has been developed for providing analytical tools for the system analysis and technology assessments in the field of nuclear research and development. This model system consists of the following four model groups. The first model block installs 5 models and can serve to analyze and generate long-term scenarios on economy-energy-environment evolution. The second model block installs 2 models and can serve to analyze the structural transition phenomena in energy-economy-environment interactions. The third model block installs 2 models and can handle power reactor installation strategy problem and long-term fuel cycle analysis. The fourth model block installs 5 models and codes and can treats cost-benefit-risk analysis and assessments. This report describes mainly the progress and the outlines of application of the model system in these years after the first report on the research and development of the model system (JAERI-M 84 - 139). (author)

  18. A parallel algorithm for the initial screening of space debris collisions prediction using the SGP4/SDP4 models and GPU acceleration

    Science.gov (United States)

    Lin, Mingpei; Xu, Ming; Fu, Xiaoyu

    2017-05-01

    Currently, a tremendous amount of space debris in Earth's orbit imperils operational spacecraft. It is essential to undertake risk assessments of collisions and predict dangerous encounters in space. However, collision predictions for an enormous amount of space debris give rise to large-scale computations. In this paper, a parallel algorithm is established on the Compute Unified Device Architecture (CUDA) platform of NVIDIA Corporation for collision prediction. According to the parallel structure of NVIDIA graphics processors, a block decomposition strategy is adopted in the algorithm. Space debris is divided into batches, and the computation and data transfer operations of adjacent batches overlap. As a consequence, the latency to access shared memory during the entire computing process is significantly reduced, and a higher computing speed is reached. Theoretically, a simulation of collision prediction for space debris of any amount and for any time span can be executed. To verify this algorithm, a simulation example including 1382 pieces of debris, whose operational time scales vary from 1 min to 3 days, is conducted on Tesla C2075 of NVIDIA. The simulation results demonstrate that with the same computational accuracy as that of a CPU, the computing speed of the parallel algorithm on a GPU is 30 times that on a CPU. Based on this algorithm, collision prediction of over 150 Chinese spacecraft for a time span of 3 days can be completed in less than 3 h on a single computer, which meets the timeliness requirement of the initial screening task. Furthermore, the algorithm can be adapted for multiple tasks, including particle filtration, constellation design, and Monte-Carlo simulation of an orbital computation.

  19. Characterizing the Survey Strategy and Initial Orbit Determination Abilities of the NASA MCAT Telescope for Geosynchronous Orbital Debris Environmental Studies

    Science.gov (United States)

    Frith, J.; Barker, E.; Cowardin, H.; Buckalew, B.; Anz-Meador, P.; Lederer, S.

    The National Aeronautics and Space Administration (NASA) Orbital Debris Program Office (ODPO) recently commissioned the Meter Class Autonomous Telescope (MCAT) on Ascension Island with the primary goal of obtaining population statistics of the geosynchronous (GEO) orbital debris environment. To help facilitate this, studies have been conducted using MCAT’s known and projected capabilities to estimate the accuracy and timeliness in which it can survey the GEO environment, including collected weather data and the proposed observational data collection cadence. To optimize observing cadences and probability of detection, on-going work using a simulated GEO debris population sampled at various cadences are run through the Constrained Admissible Region Multi Hypotheses Filter (CAR-MHF). The orbits computed from the results are then compared to the simulated data to assess MCAT’s ability to determine accurately the orbits of debris at various sample rates. The goal of this work is to discriminate GEO and near-GEO objects from GEO transfer orbit objects that can appear as GEO objects in the environmental models due to the short arc observation and an assumed circular orbit. The specific methods and results are presented here.

  20. Problems of Small Debris

    Directory of Open Access Journals (Sweden)

    V. V. Zelentsov

    2015-01-01

    Full Text Available During the exploration of outer space (as of 1/1 2011 6853 was launched spacecraft (SC are successful 6264, representing 95% of the total number of starts. The most intensively exploited space Russia (USSR (3701 starts, 94% successful, USA (2774 starts, 90% successful, China (234 starts, 96% successful and India (89 starts, 90% successful. A small part of running the spacecraft returned to Earth (manned spacecraft and transport, and the rest remained in orbit. Some of them are descended from orbit and burned up in the atmosphere, the rest remained in the OCP and turned into space debris (SD.The composition of the Cabinet is diverse: finish the job spacecraft; boosters and the last stage of launch vehicles left in orbit after SC injection; technological waste arising during the opening drop-down structures and fragments of the destroyed spacecraft. The resulting explosion orbital SD forms ellipsoidal region which orbits blasted object. Then, as a result of precession, is the distribution of objects in orbit explosion exploding spacecraft.The whole Cabinet is divided into two factions: the observed (larger than 100 mm and not observed (less than 100 mm. Observed debris katalogalizirovan and 0.2% of the total number of SD, there was no SD is the bulk - 99.8%.SC meeting working with a fragment observed SD predictable and due to changes in altitude spacecraft avoids a possible meeting. Contact spacecraft with large fragment lead to disaster (which took place at a meeting of the Russian communications satellite "Cosmos-2251" and the American machine "Iridium". Meeting with small SD is not predictable, especially if it was formed by an explosion or collision fragments together. Orbit that KM is not predictable, and the speed can be up to 10 km / s. Meeting with small particle SD no less dangerous for the spacecraft. The impact speed of spacecraft with space debris particles can reach up to 10 ... 15 km / s at such speeds the breakdown probability thin

  1. Coupled prediction of flash flood response and debris flow occurrence in an alpine basin

    Science.gov (United States)

    Amponsah, William

    2015-04-01

    Coupled prediction of flash flood response and debris flow occurrence in an alpine basin Author(s): William Amponsah1, E.I. Nikolopoulos2, Lorenzo Marchi1, Roberto Dinale4, Francesco Marra3,Davide Zoccatelli2 , Marco Borga2 Affiliation(s): 1CNR - IRPI, Corso Stati Uniti 4, 35127, Padova, ITALY, 2Department of Land, Environment, Agriculture and Forestry, University of Padova,VialeDell'Università 16, 35020, Legnaro PD, ITALY 3Department of Geography, Hebrew University of Jerusalem, ISRAEL 4Ufficio Idrografico, Provincia Autonoma di Bolzano, Bolzano, Italy This contribution examines the main hydrologic and morphologic metrics responsible for widespread triggering of debris-flows associated with flash flood occurrences in headwater alpine catchments.To achieve this objective, we investigate the precipitation forcing, hydrologic responses and landslides and debris-flow occurrences that prevailed during the August 4-5, 2012 extreme flash flood on the 140 km2 Vizze basin in the Eastern Alps of Italy. An intensive post-event survey was carried out a few days after the flood. This included the surveys of cross-sectional geometry and flood marks for the estimation of the peak discharges at multiple river sections and of the initiation and deposition areas of several debris flows. Rainfall estimates are based on careful analysis of weather radar observations and raingauge data. These data and observations permitted the implementation and calibration of a spatially distributed hydrological model, which was used to derive simulated flood hydrographs in 58 tributaries of the Vizze basin. Of these, 33 generated debris-flows, with area ranging from 0.02 km2 to 10 km2, with an average of 1.5 km2. With 130 mm peak event rainfall and a duration of 4 hours (with a max intensity of 90 mm h-1 for 10 min), model-simulated unit peak discharges range from 4 m3 s-1 km-2for elementary catchments up to 10 km2 to 2 m3 s-1 km-2 for catchments in the range of 50 - 100 km2. These are very high

  2. Multi-scale atmospheric environment modelling for urban areas

    Directory of Open Access Journals (Sweden)

    A. A. Baklanov

    2009-04-01

    Full Text Available Modern supercomputers allow realising multi-scale systems for assessment and forecasting of urban meteorology, air pollution and emergency preparedness and considering nesting with obstacle-resolved models. A multi-scale modelling system with downscaling from regional to city-scale with the Environment – HIgh Resolution Limited Area Model (Enviro-HIRLAM and to micro-scale with the obstacle-resolved Micro-scale Model for Urban Environment (M2UE is suggested and demonstrated. The M2UE validation results versus the Mock Urban Setting Trial (MUST experiment indicate satisfactory quality of the model. Necessary conditions for the choice of nested models, building descriptions, areas and resolutions of nested models are analysed. Two-way nesting (up- and down-scaling, when scale effects both directions (from the meso-scale on the micro-scale and from the micro-scale on the meso-scale, is also discussed.

  3. Predicting sediment delivery from debris flows after wildfire

    Science.gov (United States)

    Nyman, Petter; Smith, Hugh G.; Sherwin, Christopher B.; Langhans, Christoph; Lane, Patrick N. J.; Sheridan, Gary J.

    2015-12-01

    Debris flows are an important erosion process in wildfire-prone landscapes. Predicting their frequency and magnitude can therefore be critical for quantifying risk to infrastructure, people and water resources. However, the factors contributing to the frequency and magnitude of events remain poorly understood, particularly in regions outside western USA. Against this background, the objectives of this study were to i) quantify sediment yields from post-fire debris flows in southeast Australian highlands and ii) model the effects of landscape attributes on debris flow susceptibility. Sediment yields from post-fire debris flows (113-294 t ha- 1) are 2-3 orders of magnitude higher than annual background erosion rates from undisturbed forests. Debris flow volumes ranged from 539 to 33,040 m3 with hillslope contributions of 18-62%. The distribution of erosion and deposition above the fan were related to a stream power index, which could be used to model changes in yield along the drainage network. Debris flow susceptibility was quantified with a logistic regression and an inventory of 315 debris flow fans deposited in the first year after two large wildfires (total burned area = 2919 km2). The differenced normalised burn ratio (dNBR or burn severity), local slope, radiative index of dryness (AI) and rainfall intensity (from rainfall radar) were significant predictors in a susceptibility model, which produced excellent results in terms identifying channels that were eroded by debris flows (Area Under Curve, AUC = 0.91). Burn severity was the strongest predictor in the model (AUC = 0.87 when dNBR is used as single predictor) suggesting that fire regimes are an important control on sediment delivery from these forests. The analysis showed a positive effect of AI on debris flow probability in landscapes where differences in moisture regimes due to climate are associated with large variation in soil hydraulic properties. Overall, the results from this study based in the

  4. Design of plant safety model in plant enterprise engineering environment

    International Nuclear Information System (INIS)

    Gabbar, Hossam A.; Suzuki, Kazuhiko; Shimada, Yukiyasu

    2001-01-01

    Plant enterprise engineering environment (PEEE) is an approach aiming to manage the plant through its lifecycle. In such environment, safety is considered as the common objective for all activities throughout the plant lifecycle. One approach to achieve plant safety is to embed safety aspects within each function and activity within such environment. One ideal way to enable safety aspects within each automated function is through modeling. This paper proposes a theoretical approach to design plant safety model as integrated with the plant lifecycle model within such environment. Object-oriented modeling approach is used to construct the plant safety model using OO CASE tool on the basis of unified modeling language (UML). Multiple views are defined for plant objects to express static, dynamic, and functional semantics of these objects. Process safety aspects are mapped to each model element and inherited from design to operation stage, as it is naturally embedded within plant's objects. By developing and realizing the plant safety model, safer plant operation can be achieved and plant safety can be assured

  5. Designing user models in a virtual cave environment

    Energy Technology Data Exchange (ETDEWEB)

    Brown-VanHoozer, S. [Argonne National Lab., Idaho Falls, ID (United States); Hudson, R. [Argonne National Lab., IL (United States); Gokhale, N. [Madge Networks, San Jose, CA (United States)

    1995-12-31

    In this paper, the results of a first study into the use of virtual reality for human factor studies and design of simple and complex models of control systems, components, and processes are described. The objective was to design a model in a virtual environment that would reflect more characteristics of the user`s mental model of a system and fewer of the designer`s. The technology of a CAVE{trademark} virtual environment and the methodology of Neuro Linguistic Programming were employed in this study.

  6. Sorption capacity of plastic debris for hydrophobic organic chemicals.

    Science.gov (United States)

    Lee, Hwang; Shim, Won Joon; Kwon, Jung-Hwan

    2014-02-01

    The occurrence of microplastics (MPs) in the ocean is an emerging world-wide concern. Due to high sorption capacity of plastics for hydrophobic organic chemicals (HOCs), sorption may play an important role in the transport processes of HOCs. However, sorption capacity of various plastic materials is rarely documented except in the case of those used for environmental sampling purposes. In this study, we measured partition coefficients between MPs and seawater (KMPsw) for 8 polycyclic aromatic hydrocarbons (PAHs), 4 hexachlorocyclohexanes (HCHs) and 2 chlorinated benzenes (CBs). Three surrogate polymers - polyethylene, polypropylene, and polystyrene - were used as model plastic debris because they are the major components of microplastic debris found. Due to the limited solubility of HOCs in seawater and their long equilibration time, a third-phase partitioning method was used for the determination of KMPsw. First, partition coefficients between polydimethylsiloxane (PDMS) and seawater (KPDMSsw) were measured. For the determination of KMPsw, the distribution of HOCs between PDMS or plastics and solvent mixture (methanol:water=8:2 (v/v)) was determined after apparent equilibrium up to 12 weeks. Plastic debris was prepared in a laboratory by physical crushing; the median longest dimension was 320-440 μm. Partition coefficients between polyethylene and seawater obtained using the third-phase equilibrium method agreed well with experimental partition coefficients between low-density polyethylene and water in the literature. The values of KMPsw were generally in the order of polystyrene, polyethylene, and polypropylene for most of the chemicals tested. The ranges of log KMPsw were 2.04-7.87, 2.18-7.00, and 2.63-7.52 for polyethylene, polypropylene, and polystyrene, respectively. The partition coefficients of plastic debris can be as high as other frequently used partition coefficients, such as 1-octanol-water partition coefficients (Kow) and log KMPsw showed good linear

  7. An Empirical Ultra Wideband Channel Model for Indoor Laboratory Environments

    Directory of Open Access Journals (Sweden)

    A. Abolghasemi

    2009-04-01

    Full Text Available Channel measurement and modeling is an important issue when designing ultra wideband (UWB communication systems. In this paper, the results of some UWB time-domain propagation measurements performed in modern laboratory (Lab environments are presented. The Labs are equipped with many electronic and measurement devices which make them different from other indoor locations like office and residential environments. The measurements have been performed for both line of sight (LOS and non-LOS (NLOS scenarios. The measurement results are used to investigate large-scale channel characteristics and temporal dispersion parameters. The clustering Saleh- Valenzuela (S-V channel impulse response (CIR parameters are investigated based on the measurement data. The small-scale amplitude fading statistics are also studied in the environment. Then, an empirical model is presented for UWB signal transmission in the Lab environment based on the obtained results.

  8. Report of the 2014 Programming Models and Environments Summit

    Energy Technology Data Exchange (ETDEWEB)

    Heroux, Michael [US Dept. of Energy, Washington, DC (United States); Lethin, Richard [US Dept. of Energy, Washington, DC (United States)

    2016-09-19

    Programming models and environments play the essential roles in high performance computing of enabling the conception, design, implementation and execution of science and engineering application codes. Programmer productivity is strongly influenced by the effectiveness of our programming models and environments, as is software sustainability since our codes have lifespans measured in decades, so the advent of new computing architectures, increased concurrency, concerns for resilience, and the increasing demands for high-fidelity, multi-physics, multi-scale and data-intensive computations mean that we have new challenges to address as part of our fundamental R&D requirements. Fortunately, we also have new tools and environments that make design, prototyping and delivery of new programming models easier than ever. The combination of new and challenging requirements and new, powerful toolsets enables significant synergies for the next generation of programming models and environments R&D. This report presents the topics discussed and results from the 2014 DOE Office of Science Advanced Scientific Computing Research (ASCR) Programming Models & Environments Summit, and subsequent discussions among the summit participants and contributors to topics in this report.

  9. TMI-2 core debris analysis

    International Nuclear Information System (INIS)

    Cook, B.A.; Carlson, E.R.

    1985-01-01

    One of the ongoing examination tasks for the damaged TMI-2 reactor is analysis of samples of debris obtained from the debris bed presently at the top of the core. This paper summarizes the results reported in the TMI-2 Core Debris Grab Sample Examination and Analysis Report, which will be available early in 1986. The sampling and analysis procedures are presented, and information is provided on the key results as they relate to the present core condition, peak temperatures during the transient, temperature history, chemical interactions, and core relocation. The results are then summarized

  10. Limiting Future Collision Risk to Spacecraft: An Assessment of NASA's Meteoroid and Orbital Debris Programs

    Science.gov (United States)

    2011-01-01

    Over the past 50 years, various NASA communities have contributed significantly to maturing NASA s meteoroid and orbital debris (MMOD)1 programs to their current state. As a result of these community efforts, and to NASA s credit, NASA s MMOD programs and models are now widely used and respected by the providers and users of both government and commercial satellites, nationally as well as internationally. Satellites have been redesigned to protect critical components from MMOD damage by moving critical components from exterior surfaces to deep inside a satellite s structure. Orbits are monitored and altered to minimize the risk of collision with tracked orbital debris. MMOD shielding added to the International Space Station (ISS) protects critical components and astronauts from potentially catastrophic damage that might result from smaller, untracked debris and meteoroid impacts. The space shuttle, as it orbited Earth, and whether docked to the ISS or not, was optimally oriented to protect its fragile thermal protection and thermal radiation systems from MMOD damage. In addition, astronauts inspected its thermal protection system for MMOD damage before the shuttle reentered Earth s atmosphere; Orion, NASA s capsule to carry astronauts to low Earth orbit, includes designs to mitigate the threat of MMOD damage and provide increased safety to the crew. When a handful of reasonable assumptions are used in NASA s MMOD models, scenarios are uncovered that conclude that the current orbital debris environment has already reached a "tipping point." That is, the amount of debris - in terms of the population of large debris objects, as well as overall mass of debris in orbit - currently in orbit has reached a threshold where it will continually collide with itself, further increasing the population of orbital debris. This increase will lead to corresponding increases in spacecraft failures, which will only create more feedback into the system, increasing the debris population

  11. Development and Flight Demonstration of Space Debris Monitor (SDM)

    Science.gov (United States)

    Kitazawa, Yukihito; Hanada, Toshiya; Matsumoto, Haruhisa; Kobayashi, Masanori; Sakurai, Akira; Yasaka, Tetsuo; Funakoshi, Kunihiro; Hasegawa, Sunao; Akahoshi, Yasuhiro; Kimoto, Yugo; Okudaira, Osamu; Kamiya, Koki; Nakamura, Maki

    2016-07-01

    The space debris monitor (SDM) is a large-area impact sensor for in situ measurements of micro-meteoroids and space debris of the sub-millimeter to millimeter size in the near-Earth space environment. These meteoroid and debris particles are very small to be detected by ground-based observations (radars and optical telescopes) but are sufficiently large to cause serious damage to spacecraft equipment in the low Earth orbit region. The nominal detection area of the SDM is 0.1 m^2 (0.35 m × 0.3 m), but its dimensions can be easily modified to accommodate different SDM constraints. The SDM is made from a flexible printed circuit, which is produced from a thin film of a nonconductive material (such as polyimide) on which thin conductive stripes are formed in parallel. The stripe width is approximately 50 μm, and the spatial separation is approximately 100 μm, as shown in Figure 1. When a micro-debris particle with an effective diameter near to or larger than the spatial separation of the stripes (here approximately 100 μm) collides with the sensor film at a velocity sufficient to penetrate it, one or more of the stripes are cut and become nonconductive. Debris impacts can thus be detected by monitoring the electrical conductivity (resistivity) of the stripes. This sensor system can measure the size of the incident micro-debris particles by detecting the number of severed stripes. The measurement concept is registered as a patent in many countries. The first SDM was launched with HTV-5 on August 19, 2015 and represented the world's first micro-debris measurement demonstration experiment to be conducted on the ISS using the concept of conductive (resistive) strip lines for real-time debris detection.

  12. A marketing mix model for a complex and turbulent environment

    Directory of Open Access Journals (Sweden)

    R. B. Mason

    2007-12-01

    Full Text Available Purpose: This paper is based on the proposition that the choice of marketing tactics is determined, or at least significantly influenced, by the nature of the company’s external environment. It aims to illustrate the type of marketing mix tactics that are suggested for a complex and turbulent environment when marketing and the environment are viewed through a chaos and complexity theory lens. Design/Methodology/Approach: Since chaos and complexity theories are proposed as a good means of understanding the dynamics of complex and turbulent markets, a comprehensive review and analysis of literature on the marketing mix and marketing tactics from a chaos and complexity viewpoint was conducted. From this literature review, a marketing mix model was conceptualised. Findings: A marketing mix model considered appropriate for success in complex and turbulent environments was developed. In such environments, the literature suggests destabilising marketing activities are more effective, whereas stabilising type activities are more effective in simple, stable environments. Therefore the model proposes predominantly destabilising type tactics as appropriate for a complex and turbulent environment such as is currently being experienced in South Africa. Implications: This paper is of benefit to marketers by emphasising a new way to consider the future marketing activities of their companies. How this model can assist marketers and suggestions for research to develop and apply this model are provided. It is hoped that the model suggested will form the basis of empirical research to test its applicability in the turbulent South African environment. Originality/Value: Since businesses and markets are complex adaptive systems, using complexity theory to understand how to cope in complex, turbulent environments is necessary, but has not been widely researched. In fact, most chaos and complexity theory work in marketing has concentrated on marketing strategy, with

  13. TMI-2 core debris-cesium release/settling test. Volume 3

    Energy Technology Data Exchange (ETDEWEB)

    Akers, D W; Johnson, D A

    1984-12-01

    Cesium release, turbidity and airborne potential tests were conducted on 50 grams of TMI-2 core debris materials. The tests were performed on the debris in two conditions: on the as-received core debris specimen, and after crushing the debris to alter the particle size distribution. The crushing was intended to simulate the breakup of TMI-2 core material that may occur during reactor defueling. These tests are intended to assist GPU Nuclear in predicting the effect of defueling on the reactor environment.

  14. 14 CFR 417.211 - Debris analysis.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Debris analysis. 417.211 Section 417.211... TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.211 Debris analysis. (a) General. A flight safety analysis must include a debris analysis. For an orbital or suborbital launch, a debris analysis...

  15. Composition and potential origin of marine debris stranded in the Western Indian Ocean on remote Alphonse Island, Seychelles.

    Science.gov (United States)

    Duhec, Aurélie V; Jeanne, Richard F; Maximenko, Nikolai; Hafner, Jan

    2015-07-15

    The abundance, composition, and potential sources of marine debris were investigated on remote Alphonse Island, during the austral winter 2013. A total of 4743 items, weighing 142 kg, were removed from 1 km of windward beach, facing the prevailing southeasterly trade winds. Our study demonstrates the prevalence of plastic debris as a world-wide marine contaminant. Characteristics of the debris suggest it originated primarily from land-based sources. To determine their potential geographic sources we used the Surface Current from Diagnostic model of near-surface ocean currents, forced by satellite sea level and wind data. While preliminary evidence indicated the Southeast Asia to be the main source of the flotsam, the model highlighted Somalia as another potential primary source. Our study concludes that most of the collected debris entered the sea as a result of inadequate waste management and demonstrates how anthropogenic waste can negatively impact even the most remote environments. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Prevalence and composition of marine debris in Brown Booby (Sula leucogaster) nests at Ashmore Reef.

    Science.gov (United States)

    Lavers, Jennifer L; Hodgson, Jarrod C; Clarke, Rohan H

    2013-12-15

    Anthropogenic debris is ubiquitous in the marine environment and has been reported to negatively impact hundreds of species globally. Seabirds are particularly at risk from entanglement in debris due to their habit of collecting food and, in many cases, nesting material off the ocean's surface. We compared the prevalence and composition of debris in nests and along the beach at two Brown Booby (Sula leucogaster) colonies on Ashmore Reef, Timor Sea, a remote area known to contain high densities of debris transported by ocean currents. The proportion of nests with debris varied across islands (range 3-31%), likely in response to the availability of natural nesting materials. Boobies exhibited a preference for debris colour (white and black), but not type. The ephemeral nature of Brown Booby nests on Ashmore Reef may limit their utility as indicators of marine pollution, however monitoring is recommended in light of increasing demand for plastic products. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Variability of air temperature over a debris-covered glacier in the Nepalese Himalaya

    NARCIS (Netherlands)

    Steiner, J.; Pellicciotti, F.

    2016-01-01

    Estimates of melt from debris-covered glaciers require distributed estimates of meteorological variables and air temperature in particular. Meteorological data are scarce for this environment, and spatial variability of temperature over debris is poorly understood. Based on multiple measurements of

  18. A flexible Bayesian model for studying gene-environment interaction.

    Directory of Open Access Journals (Sweden)

    Kai Yu

    2012-01-01

    Full Text Available An important follow-up step after genetic markers are found to be associated with a disease outcome is a more detailed analysis investigating how the implicated gene or chromosomal region and an established environment risk factor interact to influence the disease risk. The standard approach to this study of gene-environment interaction considers one genetic marker at a time and therefore could misrepresent and underestimate the genetic contribution to the joint effect when one or more functional loci, some of which might not be genotyped, exist in the region and interact with the environment risk factor in a complex way. We develop a more global approach based on a Bayesian model that uses a latent genetic profile variable to capture all of the genetic variation in the entire targeted region and allows the environment effect to vary across different genetic profile categories. We also propose a resampling-based test derived from the developed Bayesian model for the detection of gene-environment interaction. Using data collected in the Environment and Genetics in Lung Cancer Etiology (EAGLE study, we apply the Bayesian model to evaluate the joint effect of smoking intensity and genetic variants in the 15q25.1 region, which contains a cluster of nicotinic acetylcholine receptor genes and has been shown to be associated with both lung cancer and smoking behavior. We find evidence for gene-environment interaction (P-value = 0.016, with the smoking effect appearing to be stronger in subjects with a genetic profile associated with a higher lung cancer risk; the conventional test of gene-environment interaction based on the single-marker approach is far from significant.

  19. Engineered Barrier System: Physical and Chemical Environment Model

    Energy Technology Data Exchange (ETDEWEB)

    D. M. Jolley; R. Jarek; P. Mariner

    2004-02-09

    The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports.

  20. A Comparison of the SOCIT and DebriSat Experiments

    Science.gov (United States)

    Ausay, E.; Cornejo, A.; Horn, A.; Palma, K.; Sato, T.; Blake, B.; Pistella, F.; Boyle, C.; Todd, N.; Zimmerman, J.; hide

    2017-01-01

    This paper explores the differences between, and shares the lessons learned from, two hypervelocity impact experiments critical to the update of Department of Defense (DOD) and National Aeronautics and Space Administration (NASA) satellite breakup models. The procedures as well as the processes of the fourth Satellite Orbital Debris Characterization Impact Test (SOCIT4) were analyzed and related to the ongoing DebriSat experiment. SOCIT4 accounted for about 90% of the entire satellite mass, but only analyzed approximately 59% with a total of approximately 4,700 fragments. DebriSat aims to recover and analyze 90% of the initial mass and to do so, fragments with at least a longest dimension of 2 mm are collected and processed. DebriSat's use of modern materials, especially carbon fiber, significantly increases the fragment count and to date, there are over 126,000 fragments collected. Challenges, such as procedures and human inputs, encountered throughout the DebriSat experiment are also shared. While, SOCIT4 laid the foundation for the majority of DebriSat processes, the technological advancements since SOCIT4 allow for more accurate, rigorous, and in-depth, procedures that will aid the update of satellite breakup models.

  1. The role of bank erosion on the initiation and motion of gully debris flows

    Science.gov (United States)

    Lyu, Liqun; Wang, Zhaoyin; Cui, Peng; Xu, Mengzhen

    2017-05-01

    The erosion of sediment through the exchange of momentum and energy transfer within the debris flow affects the unstable motion of the debris flow. Many models have been established to study the impact of erosion on debris flow motion, but most of the models were based on bed erosion. This paper analyzed the process of unstable motion of debris flows through an experimental flume to contrast bank erosion-dominated conditions and bed erosion-only conditions. The experiments showed that bank erosion enhanced the formation and propagation of debris flows. The volume of sediments eroded by water and the debris flow mass for the bank erosion-dominated conditions was much greater than that for the bed erosion-only conditions. The height and velocity of the debris flows fluctuated, and the total basal normal stress and pore pressure increased unsteadily along the path under both conditions. However, bank erosion increased the velocity of the debris flow and made the motion fluctuation more obvious. Physical equations were established and the analyses suggested that bank erosion-dominated debris flows had increased resistance and gradient enhancement than that of bed erosion-only debris flows.

  2. An integrative model linking feedback environment and organizational citizenship behavior.

    Science.gov (United States)

    Peng, Jei-Chen; Chiu, Su-Fen

    2010-01-01

    Past empirical evidence has suggested that a positive supervisor feedback environment may enhance employees' organizational citizenship behavior (OCB). In this study, we aim to extend previous research by proposing and testing an integrative model that examines the mediating processes underlying the relationship between supervisor feedback environment and employee OCB. Data were collected from 259 subordinate-supervisor dyads across a variety of organizations in Taiwan. We used structural equation modeling to test our hypotheses. The results demonstrated that supervisor feedback environment influenced employees' OCB indirectly through (1) both positive affective-cognition and positive attitude (i.e., person-organization fit and organizational commitment), and (2) both negative affective-cognition and negative attitude (i.e., role stressors and job burnout). Theoretical and practical implications are discussed.

  3. Event-Entity-Relationship Modeling in Data Warehouse Environments

    DEFF Research Database (Denmark)

    Bækgaard, Lars

    We use the event-entity-relationship model (EVER) to illustrate the use of entity-based modeling languages for conceptual schema design in data warehouse environments. EVER is a general-purpose information modeling language that supports the specification of both general schema structures and multi......-dimensional schemes that are customized to serve specific information needs. EVER is based on an event concept that is very well suited for multi-dimensional modeling because measurement data often represent events in multi-dimensional databases...

  4. Teletandem as a complex learning environment: Looking for a model

    Directory of Open Access Journals (Sweden)

    Annick Rivens MOMPEAN

    2015-12-01

    Full Text Available ABSTRACT This article presents a model of teletandem, i.e. tandem through desktop videoconferencing (Telles 2009. The aim of such a model is twofold: heuristic and pedagogical. It is heuristic because it enables us to understand teletandem at all its levels and partially to predict (in probabilistic terms what can happen in a teletandem environment. It is also pedagogical because it helps us formulate plans of action to improve future use and environment design. To build this model, we have drawn upon complexity theory (Larsen-Freeman & Cameron 2008, Morin 1990, which leads us to distinguish different levels of analysis before discussing the relationship between the different elements and levels leading to the complex final (yet dynamic model.

  5. Computer modeling of dosimetric pattern in aquatic environment of ...

    African Journals Online (AJOL)

    The dose distribution functions for the three sources of radiation in the environment have been reviewed. The model representing the geometry of aquatic organisms have been employed in computationally solving the dose rates to aquatic organisms with emphasis on the coastal areas of Nigeria where oil exploration ...

  6. Environment Modeling Using Runtime Values for JPF-Android

    Science.gov (United States)

    van der Merwe, Heila; Tkachuk, Oksana; Nel, Seal; van der Merwe, Brink; Visser, Willem

    2015-01-01

    Software applications are developed to be executed in a specific environment. This environment includes external native libraries to add functionality to the application and drivers to fire the application execution. For testing and verification, the environment of an application is simplified abstracted using models or stubs. Empty stubs, returning default values, are simple to generate automatically, but they do not perform well when the application expects specific return values. Symbolic execution is used to find input parameters for drivers and return values for library stubs, but it struggles to detect the values of complex objects. In this work-in-progress paper, we explore an approach to generate drivers and stubs based on values collected during runtime instead of using default values. Entry-points and methods that need to be modeled are instrumented to log their parameters and return values. The instrumented applications are then executed using a driver and instrumented libraries. The values collected during runtime are used to generate driver and stub values on- the-fly that improve coverage during verification by enabling the execution of code that previously crashed or was missed. We are implementing this approach to improve the environment model of JPF-Android, our model checking and analysis tool for Android applications.

  7. HexSim: a modeling environment for ecology and conservation.

    Science.gov (United States)

    HexSim is a powerful and flexible new spatially-explicit, individual based modeling environment intended for use in ecology, conservation, genetics, epidemiology, toxicology, and other disciplines. We describe HexSim, illustrate past applications that contributed to our >10 ye...

  8. A Virtual Environment for Resilient Infrastructure Modeling and Design

    Science.gov (United States)

    2015-09-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited A VIRTUAL ...September 2015 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE A VIRTUAL ENVIRONMENT FOR RESILIENT INFRASTRUCTURE MODELING AND...postprocessing, including convenient and efficient methods for manipulating CI network data. Moreover, the object-oriented nature of Pyomo creates a natural

  9. Modelling Global Pattern Formations for Collaborative Learning Environments

    DEFF Research Database (Denmark)

    Grappiolo, Corrado; Cheong, Yun-Gyung; Khaled, Rilla

    2012-01-01

    We present our research towards the design of a computational framework capable of modelling the formation and evolution of global patterns (i.e. group structures) in a population of social individuals. The framework is intended to be used in collaborative environments, e.g. social serious games...

  10. HexSim: a modeling environment for ecology and conservation.

    Science.gov (United States)

    HexSim is a powerful and flexible new spatially-explicit, individual based modeling environment intended for use in ecology, conservation, genetics, epidemiology, toxicology, and other disciplines. We describe HexSim, illustrate past applications that contributed to our >10 year ...

  11. Development of the Delta Shell as an integrated modeling environment

    Science.gov (United States)

    Donchyts, Gennadii; Baart, Fedor; Jagers, Bert

    2010-05-01

    Many engineering problem require the use of multiple numerical models from multiple disciplines. For example the use of river model for flow calculation coupled with groundwater model and rainfall-runoff model. These models need to be setup, coupled, run, results need to be visualized, input and output data need to be stored. For some of these steps a software or standards already exist, but there is a need for an environment allowing to perform all these steps.The goal of the present work is to create a modeling environment where models from different domains can perform all the sixe steps: setup, couple, run, visualize, store. This presentation deals with the different problems which arise when setting up a modelling framework, such as terminology, numerical aspects as well as the software development issues which arise. In order to solve these issues we use Domain Driven Design methods, available open standards and open source components. While creating an integrated modeling environment we have identified that a separation of the following domains is essential: a framework allowing to link and exchange data between models; a framework allowing to integrate different components of the environment; graphical user interface; GIS; hybrid relational and multi-dimensional data store; discipline-specific libraries: river hydrology, morphology, water quality, statistics; model-specific components Delta Shell environment which is the basis for several products such as HABITAT, SOBEK and the future Delft3D interface. It implements and integrates components covering the above mentioned domains by making use of open standards and open source components. Different components have been developed to fill in gaps. For exchaning data with the GUI an object oriented scientific framework in .NET was developed within Delta Shell somewhat similar to the JSR-275. For the GIS domain several OGC standards were used such as SFS, WCS and WFS. For storage the CF standard together with

  12. Social Skills of and Social Environments Produced by Different Holland Types: A Social Perspective on Person-Environment Fit Models.

    Science.gov (United States)

    Wampold, Bruce E.; And Others

    1995-01-01

    Describes qualitative study of chemistry laboratory groups of undergraduates to explore notion that a critical aspect of the environment in person-environment models is the nature and density of the social interactions of the people in the environment. Holland's hexagonal model of personality types was the framework used to study related…

  13. Sedimentary architecture of a sub-lacustrine debris fan: Eocene Dongying Depression, Bohai Bay Basin, east China

    Science.gov (United States)

    Liu, Jianping; Xian, Benzhong; Wang, Junhui; Ji, Youliang; Lu, Zhiyong; Liu, Saijun

    2017-12-01

    The sedimentary architectures of submarine/sublacustrine fans are controlled by sedimentary processes, geomorphology and sediment composition in sediment gravity flows. To advance understanding of sedimentary architecture of debris fans formed predominantly by debris flows in deep-water environments, a sub-lacustrine fan (Y11 fan) within a lacustrine succession has been identified and studied through the integration of core data, well logging data and 3D seismic data in the Eocene Dongying Depression, Bohai Bay Basin, east China. Six types of resedimented lithofacies can be recognized, which are further grouped into five broad lithofacies associations. Quantification of gravity flow processes on the Y11 fan is suggested by quantitative lithofacies analysis, which demonstrates that the fan is dominated by debris flows, while turbidity currents and sandy slumps are less important. The distribution, geometry and sedimentary architecture are documented using well data and 3D seismic data. A well-developed depositional lobe with a high aspect ratio is identified based on a sandstone isopach map. Canyons and/or channels are absent, which is probably due to the unsteady sediment supply from delta-front collapse. Distributary tongue-shaped debris flow deposits can be observed at different stages of fan growth, suggesting a lobe constructed by debrite tongue complexes. Within each stage of the tongue complexes, architectural elements are interpreted by wireline log motifs showing amalgamated debrite tongues, which constitute the primary fan elements. Based on lateral lithofacies distribution and vertical sequence analysis, it is proposed that lakefloor erosion, entrainment and dilution in the flow direction lead to an organized distribution of sandy debrites, muddy debrites and turbidites on individual debrite tongues. Plastic rheology of debris flows combined with fault-related topography are considered the major factors that control sediment distribution and fan

  14. An approach to accidents modeling based on compounds road environments.

    Science.gov (United States)

    Fernandes, Ana; Neves, Jose

    2013-04-01

    The most common approach to study the influence of certain road features on accidents has been the consideration of uniform road segments characterized by a unique feature. However, when an accident is related to the road infrastructure, its cause is usually not a single characteristic but rather a complex combination of several characteristics. The main objective of this paper is to describe a methodology developed in order to consider the road as a complete environment by using compound road environments, overcoming the limitations inherented in considering only uniform road segments. The methodology consists of: dividing a sample of roads into segments; grouping them into quite homogeneous road environments using cluster analysis; and identifying the influence of skid resistance and texture depth on road accidents in each environment by using generalized linear models. The application of this methodology is demonstrated for eight roads. Based on real data from accidents and road characteristics, three compound road environments were established where the pavement surface properties significantly influence the occurrence of accidents. Results have showed clearly that road environments where braking maneuvers are more common or those with small radii of curvature and high speeds require higher skid resistance and texture depth as an important contribution to the accident prevention. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Investigation of debris bed formation, spreading and coolability

    International Nuclear Information System (INIS)

    Kudinov, P.; Konovalenko, A.; Grishchenko, D.; Yakush, S.; Basso, S.; Lubchenko, N.; Karbojian, A.

    2013-08-01

    The work is motivated by the severe accident management strategy adopted in Nordic type BWRs. It is assumed that core melt ejected from the vessel will fragment, quench and form a coolable debris bed in a deep water pool below the vessel. In this work we consider phenomena relevant to the debris bed formation and coolability. Several DEFOR-A (Debris Bed Formation - Agglomeration) tests have been carried out with new corium melt material and a melt releasing nozzle mockup. The influence of the melt material, melt superheat, jet free fall height on the (i) faction of agglomerated debris, (ii) particle size distribution, (iii) ablation/plugging of the nozzle mockup has been addressed. Results of the DECOSIM (Debris Coolability Simulator) code validation against available COOLOCE data are presented in the report. The dependence of DHF on system pressure from COOLOCE experiments can be reproduced quite accurately if either the effective particle diameter or debris bed porosity is increased. For a cylindrical debris bed, good agreement is achieved in DECOSIM simulations for the particle diameter 0.89 mm and porosity 0.4. The results obtained are consistent with MEWA simulation where larger particle diameters and porosities were found to be necessary to reproduce the experimental data on DHF. It is instructive to note that results of DHF prediction are in better agreement with POMECO-HT data obtained for the same particles. It is concluded that further clarification of the discrepancies between different experiments and model predictions. In total 13 exploratory tests were carried out in PDS (particulate debris spreading) facility to clarify potential influence of the COOLOCE (VTT) facility heaters and TCs on particle self-leveling process. Results of the preliminary analysis suggest that there is no significant influence of the pins on self-leveling, at least for the air superficial velocities ranging from 0.17 up to 0.52 m/s. Further confirmatory tests might be needed

  16. Investigation of debris bed formation, spreading and coolability

    Energy Technology Data Exchange (ETDEWEB)

    Kudinov, P.; Konovalenko, A.; Grishchenko, D.; Yakush, S.; Basso, S.; Lubchenko, N.; Karbojian, A. [Royal Institute of Technology, KTH. Div. of Nuclear Power Safety, Stockholm (Sweden)

    2013-08-15

    The work is motivated by the severe accident management strategy adopted in Nordic type BWRs. It is assumed that core melt ejected from the vessel will fragment, quench and form a coolable debris bed in a deep water pool below the vessel. In this work we consider phenomena relevant to the debris bed formation and coolability. Several DEFOR-A (Debris Bed Formation - Agglomeration) tests have been carried out with new corium melt material and a melt releasing nozzle mockup. The influence of the melt material, melt superheat, jet free fall height on the (i) faction of agglomerated debris, (ii) particle size distribution, (iii) ablation/plugging of the nozzle mockup has been addressed. Results of the DECOSIM (Debris Coolability Simulator) code validation against available COOLOCE data are presented in the report. The dependence of DHF on system pressure from COOLOCE experiments can be reproduced quite accurately if either the effective particle diameter or debris bed porosity is increased. For a cylindrical debris bed, good agreement is achieved in DECOSIM simulations for the particle diameter 0.89 mm and porosity 0.4. The results obtained are consistent with MEWA simulation where larger particle diameters and porosities were found to be necessary to reproduce the experimental data on DHF. It is instructive to note that results of DHF prediction are in better agreement with POMECO-HT data obtained for the same particles. It is concluded that further clarification of the discrepancies between different experiments and model predictions. In total 13 exploratory tests were carried out in PDS (particulate debris spreading) facility to clarify potential influence of the COOLOCE (VTT) facility heaters and TCs on particle self-leveling process. Results of the preliminary analysis suggest that there is no significant influence of the pins on self-leveling, at least for the air superficial velocities ranging from 0.17 up to 0.52 m/s. Further confirmatory tests might be needed

  17. Exploring the velocity distribution of debris flows: An iteration algorithm based approach for complex cross-sections

    Science.gov (United States)

    Han, Zheng; Chen, Guangqi; Li, Yange; Wang, Wei; Zhang, Hong

    2015-07-01

    The estimation of debris-flow velocity in a cross-section is of primary importance due to its correlation to impact force, run up and superelevation. However, previous methods sometimes neglect the observed asymmetric velocity distribution, and consequently underestimate the debris-flow velocity. This paper presents a new approach for exploring the debris-flow velocity distribution in a cross-section. The presented approach uses an iteration algorithm based on the Riemann integral method to search an approximate solution to the unknown flow surface. The established laws for vertical velocity profile are compared and subsequently integrated to analyze the velocity distribution in the cross-section. The major benefit of the presented approach is that natural channels typically with irregular beds and superelevations can be taken into account, and the resulting approximation by the approach well replicates the direct integral solution. The approach is programmed in MATLAB environment, and the code is open to the public. A well-documented debris-flow event in Sichuan Province, China, is used to demonstrate the presented approach. Results show that the solutions of the flow surface and the mean velocity well reproduce the investigated results. Discussion regarding the model sensitivity and the source of errors concludes the paper.

  18. Risks of Plastic Debris : Unravelling Fact, Opinion, Perception, and Belief

    NARCIS (Netherlands)

    Koelmans, Albert A.; Besseling, Ellen; Foekema, Edwin; Kooi, Merel; Mintenig, Svenja|info:eu-repo/dai/nl/413292568; Ossendorp, Bernadette C.; Redondo-Hasselerharm, Paula E.; Verschoor, Anja; Van Wezel, Annemarie P.|info:eu-repo/dai/nl/141376074; Scheffer, Marten

    2017-01-01

    © 2017 American Chemical Society. Researcher and media alarms have caused plastic debris to be perceived as a major threat to humans and animals. However, although the waste of plastic in the environment is clearly undesirable for aesthetic and economic reasons, the actual environmental risks of

  19. Risks of Plastic Debris: Unravelling Fact, Opinion, Perception, and Belief.

    NARCIS (Netherlands)

    Koelmans, Albert A; Besseling, Ellen; Foekema, Edwin; Kooi, Merel; Mintenig, Svenja; Ossendorp, Bernadette C; Redondo-Hasselerharm, Paula E; Verschoor, Anja; van Wezel, Annemarie P; Scheffer, Marten

    2017-01-01

    Researcher and media alarms have caused plastic debris to be perceived as a major threat to humans and animals. However, although the waste of plastic in the environment is clearly undesirable for aesthetic and economic reasons, the actual environmental risks of different plastics and their

  20. Modeling Users, Context and Devices for Ambient Assisted Living Environments

    Science.gov (United States)

    Castillejo, Eduardo; Almeida, Aitor; López-de-Ipiña, Diego; Chen, Liming

    2014-01-01

    The participation of users within AAL environments is increasing thanks to the capabilities of the current wearable devices. Furthermore, the significance of considering user's preferences, context conditions and device's capabilities help smart environments to personalize services and resources for them. Being aware of different characteristics of the entities participating in these situations is vital for reaching the main goals of the corresponding systems efficiently. To collect different information from these entities, it is necessary to design several formal models which help designers to organize and give some meaning to the gathered data. In this paper, we analyze several literature solutions for modeling users, context and devices considering different approaches in the Ambient Assisted Living domain. Besides, we remark different ongoing standardization works in this area. We also discuss the used techniques, modeled characteristics and the advantages and drawbacks of each approach to finally draw several conclusions about the reviewed works. PMID:24643006

  1. Distributed collaborative environments for 21st century modeling and simulation

    Science.gov (United States)

    McQuay, William K.

    2001-09-01

    Distributed collaboration is an emerging technology that will significantly change how modeling and simulation is employed in 21st century organizations. Modeling and simulation (M&S) is already an integral part of how many organizations conduct business and, in the future, will continue to spread throughout government and industry enterprises and across many domains from research and development to logistics to training to operations. This paper reviews research that is focusing on the open standards agent-based framework, product and process modeling, structural architecture, and the integration technologies - the glue to integrate the software components. A distributed collaborative environment is the underlying infrastructure that makes communication between diverse simulations and other assets possible and manages the overall flow of a simulation based experiment. The AFRL Collaborative Environment concept will foster a major cultural change in how the acquisition, training, and operational communities employ M&S.

  2. MODELING WIND TURBINES IN THE GRIDLAB-D SOFTWARE ENVIRONMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, J.C.; Schneider, K.P.

    2009-01-01

    In recent years, the rapid expansion of wind power has resulted in a need to more accurately model the effects of wind penetration on the electricity infrastructure. GridLAB-D is a new simulation environment developed for the U.S. Department of Energy (DOE) by the Pacifi c Northwest National Laboratory (PNNL), in cooperation with academic and industrial partners. GridLAB-D was originally written and designed to help integrate end-use smart grid technologies, and it is currently being expanded to include a number of other technologies, including distributed energy resources (DER). The specifi c goal of this project is to create a preliminary wind turbine generator (WTG) model for integration into GridLAB-D. As wind power penetration increases, models are needed to accurately study the effects of increased penetration; this project is a beginning step at examining these effects within the GridLAB-D environment. Aerodynamic, mechanical and electrical power models were designed to simulate the process by which mechanical power is extracted by a wind turbine and converted into electrical energy. The process was modeled using historic atmospheric data, collected over a period of 30 years as the primary energy input. This input was then combined with preliminary models for synchronous and induction generators. Additionally, basic control methods were implemented, using either constant power factor or constant power modes. The model was then compiled into the GridLAB-D simulation environment, and the power outputs were compared against manufacturers’ data and then a variation of the IEEE 4 node test feeder was used to examine the model’s behavior. Results showed the designs were suffi cient for a prototype model and provided output power similar to the available manufacturers’ data. The prototype model is designed as a template for the creation of new modules, with turbine-specifi c parameters to be added by the user.

  3. CAD ACTIVE MODELS: AN INNOVATIVE METHOD IN ASSEMBLY ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    NADDEO Alessandro

    2010-07-01

    Full Text Available The aim of this work is to show the use and the versatility of the active models in different applications. It has been realized an active model of a cylindrical spring and it has been applied in two mechanisms, different for typology and for backlash loads. The first example is a dynamometer in which nthe cylindrical spring is loaded by traction forces, while the second example is made up from a pressure valve in which the cylindrical-conic spring works under compression. The imposition of the loads in both cases, has allowed us to evaluate the model of the mechanism in different working conditions, also in assembly environment.

  4. Operational Modelling of the Aerospace Propagation Environment. Volume II

    Science.gov (United States)

    1978-11-01

    radiative transfer models are rarely available in a battlefield environment. tnly secondary ECNET parameters may be available. Hence, current modeling and...adopthe done lee traitements a 6tA de remplacer chaque valeur X4Dar son rang. Clest-h-diro quo Zj eet rermplacO pax Is nombre d’dohant~illons do X. qui...out uslub r -aItistial model relevant to thobe arcac If the Urt chooses a terraln typ- from the lIs- glvtn ,hov, a stetistlcol ’irregulal terr .’n

  5. Utilizing Weather RADAR for Rapid Location of Meteorite Falls and Space Debris Re-Entry

    Science.gov (United States)

    Fries, Marc D.

    2016-01-01

    This activity utilizes existing NOAA weather RADAR imagery to locate meteorite falls and space debris falls. The near-real-time availability and spatial accuracy of these data allow rapid recovery of material from both meteorite falls and space debris re-entry events. To date, at least 22 meteorite fall recoveries have benefitted from RADAR detection and fall modeling, and multiple debris re-entry events over the United States have been observed in unprecedented detail.

  6. Origin of marine debris is related to disposable packs of ultra-processed food.

    Science.gov (United States)

    Andrades, Ryan; Martins, Agnaldo S; Fardim, Lorena M; Ferreira, Juliana S; Santos, Robson G

    2016-08-15

    Marine debris is currently distributed worldwide, and the discard and contamination pose hazards to human and wildlife health. One of the gaps in debris science is tracking the source of debris to better evaluate and avoid the pathway of debris from the source to marine environment. For this, we evaluated three beaches of different urbanization levels and environmental influences; a low urbanized beach, a highly urbanized beach and a non-urbanized estuary-associated beach, in order to determine the sources and original use of debris. Plastic was the major material found on beaches, and the urbanized beach recorded the highest debris densities. Marine debris was primarily from land-based sources, and the debris recorded in all beaches was mainly assigned as food-related items. Our results highlight the major presence of disposable and short-lived products comprising the majority of debris that enters the ocean and draw attention to the unsustainable lifestyle of current society. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Combining litter observations with a regional ocean model to identify sources and sinks of floating debris in a semi-enclosed basin: The Adriatic Sea

    DEFF Research Database (Denmark)

    Carlson, Daniel F.; Suaria, Giuseppe; Aliani, Stefano

    2017-01-01

    or to predict its fate, crucial information for management and mitigation policies. Particle tracking techniques have seen extensive use in these roles, however, most previous studies have used simplistic initial conditions based on bulk average inputs of debris to the system. Here, observations of floating......Visual ship transect surveys provide crucial information about the density, and spatial distribution of floating anthropogenic litter in a basin. However, such observations provide a 'snapshot' of local conditions at a given time and cannot be used to deduce the provenance of the litter...

  8. A Multiagent Modeling Environment for Simulating Work Practice in Organizations

    Science.gov (United States)

    Sierhuis, Maarten; Clancey, William J.; vanHoof, Ron

    2004-01-01

    In this paper we position Brahms as a tool for simulating organizational processes. Brahms is a modeling and simulation environment for analyzing human work practice, and for using such models to develop intelligent software agents to support the work practice in organizations. Brahms is the result of more than ten years of research at the Institute for Research on Learning (IRL), NYNEX Science & Technology (the former R&D institute of the Baby Bell telephone company in New York, now Verizon), and for the last six years at NASA Ames Research Center, in the Work Systems Design and Evaluation group, part of the Computational Sciences Division (Code IC). Brahms has been used on more than ten modeling and simulation research projects, and recently has been used as a distributed multiagent development environment for developing work practice support tools for human in-situ science exploration on planetary surfaces, in particular a human mission to Mars. Brahms was originally conceived of as a business process modeling and simulation tool that incorporates the social systems of work, by illuminating how formal process flow descriptions relate to people s actual located activities in the workplace. Our research started in the early nineties as a reaction to experiences with work process modeling and simulation . Although an effective tool for convincing management of the potential cost-savings of the newly designed work processes, the modeling and simulation environment was only able to describe work as a normative workflow. However, the social systems, uncovered in work practices studied by the design team played a significant role in how work actually got done-actual lived work. Multi- tasking, informal assistance and circumstantial work interactions could not easily be represented in a tool with a strict workflow modeling paradigm. In response, we began to develop a tool that would have the benefits of work process modeling and simulation, but be distinctively able to

  9. The Capturing of Space Debris with a Spaceborne Multi-fingered Gripper

    Directory of Open Access Journals (Sweden)

    Zhang Yin

    2017-01-01

    Full Text Available With the massive launching of spacecraft, more and more space debris are making the low Earth orbit (LEO much more crowded which seriously affects the normal flight of other spacecrafts. Space debris removal has become a very urgent issue concerned by numerous countries. In this paper, using SwissCube as a target, the capturing of space debris with a spaceborne four-fingered gripper was studied in order to obtain the key factors that affect the capturing effect. The contact state between the gripper fingers and SwissCube was described using a defined contact matrix. The law of momentum conservation was used to model the motion variations of the gripper and SwissCube before and after the capturing process. A zero-gravity simulation environment was built using ADAMS software. Two typical kinds of capturing processes were simulated considering different stiffness of fingers and different friction conditions between fingers and SwissCube. Comparisons between results obtained with the law of momentum conservation and those from ADAMS simulation show that the theoretical calculations and simulation results are consistent. In addition, through analyzing the capturing process, a valuable finding was obtained that the contact friction and finger flexibility are two very important factors that affect the capturing result.

  10. Unravelling the evolution and avulsion mechanisms of debris-flow fans

    Science.gov (United States)

    de Haas, Tjalling; Densmore, Alex; Stoffel, Markus; Ballesteros-Cánovas, Juan; Suwa, Hiroshi; Imaizumi, Fumitoshi; Wasklewicz, Thad

    2017-04-01

    Debris flows are water-laden masses of soil and fragmented rock that rush down mountainsides and spill out onto valley floors and alluvial fans, where they can devastate people and property. Expansion of human population into mountainous regions and the effects of global warming have increased the hazardous effects of debris flows over the last decades. Debris-flow channel avulsions (channel shifts) are critical to debris-flow fan evolution and hazard mitigation, because avulsions distribute debris flows and associated hazards through space and time. However, both the long-term evolution of debris-flow fans and their avulsion process are poorly understood. We aim to unravel the spatio-temporal patterns of debris-flow fan evolution and their avulsion mechanisms and tendency. Here we present a combined analysis of laboratory experiments; field data (repeat topographic analyses and dendrogeomorphological and lichenometrical reconstructions from debris-flow fans in Japan, USA, Switserland and France) and numerical modelling, identifying the main drivers of avulsion on debris-flow fans and their associated spatio-temporal evolution. We show that there are two main processes driving avulsions on debris-flow fans operating at two distinct timescales. (1) Channel plugs locally block channels forcing subsequent flows to avulse and follow alternative flow paths. The frequent but stochastic nature of channel-plug formation leads to a partly unpredictable avulsion and spatial depositional patterns on timescales of a few events. (2) Nevertheless, over timescales of tens of events the average locus of debris-flow deposition is observed to gradually shift towards the topographically lower parts of a fan, highlighting the importance of topographic compensation in the avulsion process on debris-flow fans. We further show that the magnitude-frequency distribution of the debris flows feeding a fan strongly affects the spatio-temporal patterns of deposition. Our results have strong

  11. Environment

    DEFF Research Database (Denmark)

    Valentini, Chiara

    2017-01-01

    The term environment refers to the internal and external context in which organizations operate. For some scholars, environment is defined as an arrangement of political, economic, social and cultural factors existing in a given context that have an impact on organizational processes and structures....... For others, environment is a generic term describing a large variety of stakeholders and how these interact and act upon organizations. Organizations and their environment are mutually interdependent and organizational communications are highly affected by the environment. This entry examines the origin...... and development of organization-environment interdependence, the nature of the concept of environment and its relevance for communication scholarships and activities....

  12. Attitude Motion of Cylindrical Space Debris during Its Removal by Ion Beam

    Directory of Open Access Journals (Sweden)

    Vladimir S. Aslanov

    2017-01-01

    Full Text Available The paper is devoted to the problem of space debris mitigation. Contactless method of the space debris deorbiting is considered. It is assumed that ion thrusters on the active spacecraft create the ion flow, which blows the debris and slows it down. The objectives of this work are the development of mathematical models and the research of space debris motion under the action of the ion flow. It is supposed that the space debris is a rigid body of a cylindrical shape. Calculation of ion beam force and torque was performed for a self-similar model of plasma plume expansion using the hypothesis of ion fully diffused reflection from a surface. A mathematical model describing plane motions of the cylindrical space debris under the influence of gravity gradient torque and the ion flux was constructed. It was shown that motion of the space debris around its center of mass has a significant effect on its removal time. Phase portraits, describing the motion of the space debris relative to its center of mass, were constructed. Comparison of the descent times in different motion modes was carried out. The results can be used to create new effective systems of large space debris removal.

  13. Educational complex of light-colored modeling of urban environment

    Directory of Open Access Journals (Sweden)

    Karpenko Vladimir E.

    2018-01-01

    Full Text Available Mechanisms, methodological tools and structure of a training complex of light-colored modeling of the urban environment are developed in this paper. The following results of the practical work of students are presented: light composition and installation, media facades, lighting of building facades, city streets and embankment. As a result of modeling, the structure of the light form is determined. Light-transmitting materials and causing characteristic optical illusions, light-visual and light-dynamic effects (video-dynamics and photostatics, basic compositional techniques of light form are revealed. The main elements of the light installation are studied, including a light projection, an electronic device, interactivity and relationality of the installation, and the mechanical device which becomes a part of the installation composition. The meaning of modern media facade technology is the transformation of external building structures and their facades into a changing information cover, into a media content translator using LED technology. Light tectonics and the light rhythm of the plastics of the architectural object are built up through point and local illumination, modeling of the urban ensemble assumes the structural interaction of several light building models with special light-composition techniques. When modeling the social and pedestrian environment, the lighting parameters depend on the scale of the chosen space and are adapted taking into account the visual perception of the pedestrian, and the atmospheric effects of comfort and safety of the environment are achieved with the help of special light compositional techniques. With the aim of realizing the tasks of light modeling, a methodology has been created, including the mechanisms of models, variability and complementarity. The perspectives of light modeling in the context of structural elements of the city, neuropsychology, wireless and bioluminescence technologies are proposed

  14. Modeling of the Martian environment for radiation analysis

    International Nuclear Information System (INIS)

    De Angelis, G.; Wilson, J.W.; Clowdsley, M.S.; Qualls, G.D.; Singleterry, R.C.

    2006-01-01

    A model for the radiation environment to be found on the planet Mars due to Galactic Cosmic Rays (GCR) has been developed. Solar modulated primary particles rescaled for conditions at Mars are transported through the Martian atmosphere down to the surface, with altitude and backscattering patterns taken into account. The altitude to compute the atmospheric thickness profile has been determined by using a model for the topography based on the data provided by the Mars Orbiter Laser Altimeter (MOLA) instrument on board the Mars Global Surveyor (MGS) spacecraft. The Mars surface composition has been modeled based on averages over the measurements obtained from orbiting spacecraft and at various landing sites, taking into account the possible volatile inventory (e.g. CO 2 and H 2 O ices) along with its time variations throughout the Martian year. The Mars Radiation Environment Model has been made available worldwide through the Space Ionizing Radiation Effects and Shielding Tools (SIREST) website, a project of NASA Langley Research Center. This site has been developed to provide the scientific and engineering communities with an interactive site containing a variety of environmental models, shield evaluation codes, and radiation response models to allow a thorough assessment of ionizing radiation risk for current and future space missions

  15. Technological learning in energy-environment-economy modelling: A survey

    International Nuclear Information System (INIS)

    Kahouli-Brahmi, Sondes

    2008-01-01

    This paper aims at providing an overview and a critical analysis of the technological learning concept and its incorporation in energy-environment-economy models. A special emphasis is put on surveying and discussing, through the so-called learning curve, both studies estimating learning rates in the energy field and studies incorporating endogenous technological learning in bottom-up and top-down models. The survey of learning rate estimations gives special attention to interpreting and explaining the sources of variability of estimated rates, which is shown to be mainly inherent in R and D expenditures, the problem of omitted variable bias, the endogeneity relationship and the role of spillovers. Large-scale models survey show that, despite some methodological and computational complexity related to the non-linearity and the non-convexity associated with the learning curve incorporation, results of the numerous modelling experiments give several new insights with regard to the analysis of the prospects of specific technological options and their cost decrease potential (bottom-up models), and with regard to the analysis of strategic considerations, especially inherent in the innovation and energy diffusion process, in particular the energy sector's endogenous responses to environment policy instruments (top-down models)

  16. A spatially structured metapopulation model within a stochastic environment.

    Science.gov (United States)

    Smith, Andrew G

    2017-09-01

    Populations often exist, either by choice or by external pressure, in a fragmented way, referred to as a metapopulation. Typically, the dynamics accounted for within metapopulation models are assumed to be static. For example, patch occupancy models often assume that the colonisation and extinction rates do not change, while spatially structured models often assume that the rates of births, deaths and migrations do not depend on time. While some progress has been made when these dynamics are changing deterministically, less is known when the changes are stochastic. It can be quite common that the environment a population inhabits determines how these dynamics change over time. Changes to this environment can have a large impact on the survival probability of a population and such changes will often be stochastic. The typical metapopulation model allows for catastrophes that could eradicate most, if not all, individuals on an entire patch. It is this type of phenomenon that this article addresses. A Markov process is developed that models the number of individuals on each patch within a metapopulation. An approximation for the original model is presented in the form of a piecewise-deterministic Markov process and the approximation is analysed to present conditions for extinction. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. LINDOZ model for Finland environment: Model description and evaluation of model performance

    International Nuclear Information System (INIS)

    Galeriu, D.; Apostoaie, A.I.; Mocanu, N.; Paunescu, N.

    1996-01-01

    LINDOZ model was developed as a realistic assessment tool for radioactive contamination of the environment. It was designed to produce estimates for the concentration of the pollutant in different compartments of the terrestrial ecosystem (soil, vegetation, animal tissue, and animal products), and to evaluate human exposure to the contaminant (concentration in whole human body, and dose to humans) from inhalation, ingestion and external irradiation. The user can apply LINDOZ for both routine and accidental type of releases. 2 figs, 2 tabs

  18. Fisheries as a source of marine debris on beaches in the United Kingdom.

    Science.gov (United States)

    Unger, Antonia; Harrison, Nancy

    2016-06-15

    Marine debris from ships has persisted and remains a concern despite international agreements such as MARPOL. We report on an analysis of beach litter based on a data set established by the Marine Conservation Society (MSC) Beachwatch weekends. Debris collected around the UK was divided into three main types of debris: (1) plastic, (2) fishing, and (3) fishing related plastic and rubber. Correspondence analysis (CA) was used to examine patterns in the occurrence of debris types on a total of 1023 beaches and debris attributable to fishing was identified on clusters of beaches mainly located on the coasts of Scotland and along the English Channel. General Linear model (GLM) identified fishing as the highest explanatory factor when testing for relationships between litter and proximity to fishing ports and grounds. The results add to the growing body of evidence that the fishing industry is largely responsible for marine debris. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  19. Apparent rotation properties of space debris extracted from photometric measurements

    Science.gov (United States)

    Šilha, Jiří; Pittet, Jean-Noël; Hamara, Michal; Schildknecht, Thomas

    2018-02-01

    Knowledge about the rotation properties of space debris objects is essential for the active debris removal missions, accurate re-entry predictions and to investigate the long-term effects of the space environment on the attitude motion change. Different orbital regions and object's physical properties lead to different attitude states and their change over time. Since 2007 the Astronomical Institute of the University of Bern (AIUB) performs photometric measurements of space debris objects. To June 2016 almost 2000 light curves of more than 400 individual objects have been acquired and processed. These objects are situated in all orbital regions, from low Earth orbit (LEO), via global navigation systems orbits and high eccentricity orbit (HEO), to geosynchronous Earth orbit (GEO). All types of objects were observed including the non-functional spacecraft, rocket bodies, fragmentation debris and uncorrelated objects discovered during dedicated surveys. For data acquisition, we used the 1-meter Zimmerwald Laser and Astrometry Telescope (ZIMLAT) at the Swiss Optical Ground Station and Geodynamics Observatory Zimmerwald, Switzerland. We applied our own method of phase-diagram reconstruction to extract the apparent rotation period from the light curve. Presented is the AIUB's light curve database and the obtained rotation properties of space debris as a function of object type and orbit.

  20. Impacts of Woody Debris on Fluvial Processes and Channel Morphology in Stable and Unstable Streams

    National Research Council Canada - National Science Library

    Wallerstein, N

    1996-01-01

    .... The aim of this research is to gain an improved understanding of the basin-wide impact of LWD dynamics in unstable and stable channel environments and to develop a set of coherent debris management...

  1. Impacts of Woody Debris on Fluvial Processes and Channel Morphology in Stable and Unstable Streams

    National Research Council Canada - National Science Library

    Wallerstein, N

    1997-01-01

    .... The aim of this research is to gain an improved understanding of the basin-wide impact of LWD dynamics in unstable and stable channel environments and to develop a set of coherent debris management...

  2. Modeling the cometary environment using a fluid approach

    Science.gov (United States)

    Shou, Yinsi

    Comets are believed to have preserved the building material of the early solar system and to hold clues to the origin of life on Earth. Abundant remote observations of comets by telescopes and the in-situ measurements by a handful of space missions reveal that the cometary environments are complicated by various physical and chemical processes among the neutral gases and dust grains released from comets, cometary ions, and the solar wind in the interplanetary space. Therefore, physics-based numerical models are in demand to interpret the observational data and to deepen our understanding of the cometary environment. In this thesis, three models using a fluid approach, which include important physical and chemical processes underlying the cometary environment, have been developed to study the plasma, neutral gas, and the dust grains, respectively. Although models based on the fluid approach have limitations in capturing all of the correct physics for certain applications, especially for very low gas density environment, they are computationally much more efficient than alternatives. In the simulations of comet 67P/Churyumov-Gerasimenko at various heliocentric distances with a wide range of production rates, our multi-fluid cometary neutral gas model and multi-fluid cometary dust model have achieved comparable results to the Direct Simulation Monte Carlo (DSMC) model, which is based on a kinetic approach that is valid in all collisional regimes. Therefore, our model is a powerful alternative to the particle-based model, especially for some computationally intensive simulations. Capable of accounting for the varying heating efficiency under various physical conditions in a self-consistent way, the multi-fluid cometary neutral gas model is a good tool to study the dynamics of the cometary coma with different production rates and heliocentric distances. The modeled H2O expansion speeds reproduce the general trend and the speed's nonlinear dependencies of production rate

  3. Disaster Debris Recovery Database - Landfills

    Science.gov (United States)

    The US EPA Region 5 Disaster Debris Recovery Database includes public datasets of over 6,000 composting facilities, demolition contractors, transfer stations, landfills and recycling facilities for construction and demolition materials, electronics, household hazardous waste, metals, tires, and vehicles in the states of Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, North Dakota, Ohio, Pennsylvania, South Dakota, West Virginia and Wisconsin.In this update, facilities in the 7 states that border the EPA Region 5 states were added to assist interstate disaster debris management. Also, the datasets for composters, construction and demolition recyclers, demolition contractors, and metals recyclers were verified and source information added for each record using these sources: AGC, Biocycle, BMRA, CDRA, ISRI, NDA, USCC, FEMA Debris Removal Contractor Registry, EPA Facility Registry System, and State and local listings.

  4. GENI: A graphical environment for model-based control

    International Nuclear Information System (INIS)

    Kleban, S.; Lee, M.; Zambre, Y.

    1989-10-01

    A new method to operate machine and beam simulation programs for accelerator control has been developed. Existing methods, although cumbersome, have been used in control systems for commissioning and operation of many machines. We developed GENI, a generalized graphical interface to these programs for model-based control. This ''object-oriented''-like environment is described and some typical applications are presented. 4 refs., 5 figs

  5. Home-Network Security Model in Ubiquitous Environment

    OpenAIRE

    Dong-Young Yoo; Jong-Whoi Shin; Jin-Young Choi

    2007-01-01

    Social interest and demand on Home-Network has been increasing greatly. Although various services are being introduced to respond to such demands, they can cause serious security problems when linked to the open network such as Internet. This paper reviews the security requirements to protect the service users with assumption that the Home-Network environment is connected to Internet and then proposes the security model based on the requirement. The proposed security mode...

  6. Modelling in waters geochemistry. Concepts and applications in environment

    International Nuclear Information System (INIS)

    Windt, L. de; Lee, J.V.D.; Schmitt, J.M.

    2005-01-01

    The aim of this work is to give the main point of the physico-chemical concepts and of the mathematical laws on which are based the geochemical modelling of waters, while presenting concrete and typical applications examples to the problems of environment and of water resources management. In a table (Doc. AF 6530) are gathered the distribution sources of softwares and of thermodynamic data banks. (O.M.)

  7. The Top 10 Questions for Active Debris Removal

    Science.gov (United States)

    Liou, J. -C.

    2010-01-01

    This slide presentation reviews the requirement and issues around removal of debris from the earth orbital environment. The 10 questions discussed are: 1. Which region (LEO/MEO/GEO) has the fastest projected growth rate and the highest collision activities? 2. Can the commonly-adopted mitigation measures stabilize the future environment? 3. What are the objectives of active debris removal (ADR)? 4. How can effective ADR target selection criteria to stabilize the future LEO environment be defined? 5. What are the keys to remediate the future LEO environment? 6. What is the timeframe for ADR implementation? 7. What is the effect of practical/operational constraints? 8. What are the collision probabilities and masses of the current objects? 9. What are the benefits of collision avoidance maneuvers? 10. What is the next step?

  8. Global Analysis of Anthropogenic Debris Ingestion by Sea Turtles

    Science.gov (United States)

    Schuyler, Qamar; Hardesty, Britta Denise; Wilcox, Chris; Townsend, Kathy

    2014-01-01

    Ingestion of marine debris can have lethal and sublethal effects on sea turtles and other wildlife. Although researchers have reported on ingestion of anthropogenic debris by marine turtles and implied incidences of debris ingestion have increased over time, there has not been a global synthesis of the phenomenon since 1985. Thus, we analyzed 37 studies published from 1985 to 2012 that report on data collected from before 1900 through 2011. Specifically, we investigated whether ingestion prevalence has changed over time, what types of debris are most commonly ingested, the geographic distribution of debris ingestion by marine turtles relative to global debris distribution, and which species and life-history stages are most likely to ingest debris. The probability of green (Chelonia mydas) and leatherback turtles (Dermochelys coriacea) ingesting debris increased significantly over time, and plastic was the most commonly ingested debris. Turtles in nearly all regions studied ingest debris, but the probability of ingestion was not related to modeled debris densities. Furthermore, smaller, oceanic-stage turtles were more likely to ingest debris than coastal foragers, whereas carnivorous species were less likely to ingest debris than herbivores or gelatinovores. Our results indicate oceanic leatherback turtles and green turtles are at the greatest risk of both lethal and sublethal effects from ingested marine debris. To reduce this risk, anthropogenic debris must be managed at a global level. Análisis Global de la Ingesta de Residuos Antropogénicos por Tortugas Marinas La ingesta de residuos marinos puede tener efectos letales y subletales sobre las tortugas marinas y otros animales. Aunque hay investigadores que han reportado la ingesta de residuos antropogénicos por tortugas marinas y la incidencia de la ingesta de residuos ha incrementado con el tiempo, no ha habido una síntesis global del fenómeno desde 1985. Por esto analizamos 37 estudios publicados, desde

  9. A model for hypermedia learning environments based on electronic books

    Directory of Open Access Journals (Sweden)

    Ignacio Aedo

    1997-12-01

    Full Text Available Current hypermedia learning environments do not have a common development basis. Their designers have often used ad-hoc solutions to solve the learning problems they have encountered. However, hypermedia technology can take advantage of employing a theoretical scheme - a model - which takes into account various kinds of learning activities, and solves some of the problems associated with its use in the learning process. The model can provide designers with the tools for creating a hypermedia learning system, by allowing the elements and functions involved in the definition of a specific application to be formally represented.

  10. A model for dispersion of contaminants in the subway environment

    Energy Technology Data Exchange (ETDEWEB)

    Coke, L. R.; Sanchez, J. G.; Policastro, A. J.

    2000-05-03

    Although subway ventilation has been studied extensively, very little has been published on dispersion of contaminants in the subway environment. This paper presents a model that predicts dispersion of contaminants in a complex subway system. It accounts for the combined transient effects of train motion, station airflows, train car air exchange rates, and source release properties. Results are presented for a range of typical subway scenarios. The effects of train piston action and train car air exchange are discussed. The model could also be applied to analyze the environmental impact of hazardous materials releases such as chemical and biological agents.

  11. The influx of marine debris from the Great Japan Tsunami of 2011 to North American shorelines.

    Science.gov (United States)

    Murray, Cathryn Clarke; Maximenko, Nikolai; Lippiatt, Sherry

    2018-01-10

    Marine debris is one of the leading threats to the ocean and the Great East Japan Earthquake and tsunami on March 11, 2011 washed away an estimated 5million tons of debris in a single, tragic event. Here we used shoreline surveys, disaster debris reports and ocean drift models to investigate the temporal and spatial trends in the arrival of tsunami marine debris. The increase in debris influx to surveyed North American and Hawaiian shorelines was substantial and significant, representing a 10 time increase over the baseline in northern Washington State where a long term dataset was available. The tsunami event brought different types of debris along the coast, with high-windage items dominant in Alaska and British Columbia and large, medium-windage items in Washington State and Oregon. Recorded cumulative debris landings to North America were close to 100,000 items in the four year study period. The temporal peaks in measured shoreline debris and debris reports match the ocean drift model solutions. Mitigation and monitoring activities, such as shoreline surveys, provide crucial data and monitoring for potential impacts should be continued in the future. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

  12. MASCARET: creating virtual learning environments from system modelling

    Science.gov (United States)

    Querrec, Ronan; Vallejo, Paola; Buche, Cédric

    2013-03-01

    The design process for a Virtual Learning Environment (VLE) such as that put forward in the SIFORAS project (SImulation FOR training and ASsistance) means that system specifications can be differentiated from pedagogical specifications. System specifications can also be obtained directly from the specialists' expertise; that is to say directly from Product Lifecycle Management (PLM) tools. To do this, the system model needs to be considered as a piece of VLE data. In this paper we present Mascaret, a meta-model which can be used to represent such system models. In order to ensure that the meta-model is capable of describing, representing and simulating such systems, MASCARET is based SysML1, a standard defined by Omg.

  13. Precipitates/Salts Model Calculations for Various Drift Temperature Environments

    International Nuclear Information System (INIS)

    Marnier, P.

    2001-01-01

    The objective and scope of this calculation is to assist Performance Assessment Operations and the Engineered Barrier System (EBS) Department in modeling the geochemical effects of evaporation within a repository drift. This work is developed and documented using procedure AP-3.12Q, Calculations, in support of ''Technical Work Plan For Engineered Barrier System Department Modeling and Testing FY 02 Work Activities'' (BSC 2001a). The primary objective of this calculation is to predict the effects of evaporation on the abstracted water compositions established in ''EBS Incoming Water and Gas Composition Abstraction Calculations for Different Drift Temperature Environments'' (BSC 2001c). A secondary objective is to predict evaporation effects on observed Yucca Mountain waters for subsequent cement interaction calculations (BSC 2001d). The Precipitates/Salts model is documented in an Analysis/Model Report (AMR), ''In-Drift Precipitates/Salts Analysis'' (BSC 2001b)

  14. Modeling socio-cultural processes in network-centric environments

    Science.gov (United States)

    Santos, Eunice E.; Santos, Eugene, Jr.; Korah, John; George, Riya; Gu, Qi; Kim, Keumjoo; Li, Deqing; Russell, Jacob; Subramanian, Suresh

    2012-05-01

    The major focus in the field of modeling & simulation for network centric environments has been on the physical layer while making simplifications for the human-in-the-loop. However, the human element has a big impact on the capabilities of network centric systems. Taking into account the socio-behavioral aspects of processes such as team building, group decision-making, etc. are critical to realistically modeling and analyzing system performance. Modeling socio-cultural processes is a challenge because of the complexity of the networks, dynamism in the physical and social layers, feedback loops and uncertainty in the modeling data. We propose an overarching framework to represent, model and analyze various socio-cultural processes within network centric environments. The key innovation in our methodology is to simultaneously model the dynamism in both the physical and social layers while providing functional mappings between them. We represent socio-cultural information such as friendships, professional relationships and temperament by leveraging the Culturally Infused Social Network (CISN) framework. The notion of intent is used to relate the underlying socio-cultural factors to observed behavior. We will model intent using Bayesian Knowledge Bases (BKBs), a probabilistic reasoning network, which can represent incomplete and uncertain socio-cultural information. We will leverage previous work on a network performance modeling framework called Network-Centric Operations Performance and Prediction (N-COPP) to incorporate dynamism in various aspects of the physical layer such as node mobility, transmission parameters, etc. We validate our framework by simulating a suitable scenario, incorporating relevant factors and providing analyses of the results.

  15. Space Debris Elimination (SpaDE)

    Data.gov (United States)

    National Aeronautics and Space Administration — The amount of debris in low Earth orbit (LEO) has increased rapidly over the last twenty years. This prevalence of debris increases the likelihood of cascading...

  16. The ecological impacts of marine debris

    NARCIS (Netherlands)

    Rochman, Chelsea M.; Browne, Mark Anthony; Underwood, A.J.; Franeker, Van Jan A.; Thompson, Richard C.; Amaral-Zettler, Linda A.

    2016-01-01

    Anthropogenic debris contaminates marine habitats globally, leading to several perceived ecological impacts. Here, we critically and systematically review the literature regarding impacts of debris from several scientific fields to understand the weight of evidence regarding the ecological

  17. Marine Debris Research, Prevention, and Reduction Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Marine Debris Research, Prevention, and Reduction Act legally establishes the National Oceanic and Atmospheric Administration's (NOAA) Marine Debris Program. The...

  18. DebriSat Project Update and Planning

    Science.gov (United States)

    Sorge, M.; Krisko, P. H.

    2016-01-01

    DebriSat Reporting Topics: DebriSat Fragment Analysis Calendar; Near-term Fragment Extraction Strategy; Fragment Characterization and Database; HVI (High-Velocity Impact) Considerations; Requirements Document.

  19. CDOT rapid debris removal research project.

    Science.gov (United States)

    2014-07-01

    Highway debris represents a traffic safety problem that requires a prompt response from state or local transportation : agencies. The most common practice for debris removal currently is for agency personnel to leave their vehicles and : remove the d...

  20. Active debris removal GNC challenges over design and required ground validation

    Science.gov (United States)

    Colmenarejo, Pablo; Avilés, Marcos; di Sotto, Emanuele

    2015-06-01

    capture technologies. This paper focuses on some specific aspects and technologies related to ADR terminal phases involved technologies and ground validation approaches: (1) Terminal ADR approach phase using visual-based navigation (VBN). Potential Image Processing techniques and preliminary performances will be described, together with the challenge of generating on-ground realistic images as input for the HW/SW VBN system. Some results of image generation (including comparison with real flight image missions) and processing using GMV's Optical Laboratory (image generation by rendering spacecraft 3D models and projecting on a screen in front of the HW camera) and using GMV's platform-art ® laboratory to reproduce space-realistic physical scenarios (to be captured by a HW camera) using 1:1 physical spacecraft mock-ups in an absolutely dark environment with a Sun-like single illumination source. (2) Ground validation of GNC systems based on HW-in-the-Loop (HIL) test facilities, including realistic space-representative avionics (at processor, interfaces and real-time operating system), realistic and air-to-air stimulated breadboard perception sensors (IMU, optical cameras, laser 3D sensors) through the use of dynamic robotic devices hosting the active vehicle and debris mock-ups and reproducing accurately the spatial relative dynamic corresponding to an ADR scenario. This type of ground validation can effectively achieve validation in relevant environment, till TRL (Technology Readiness Level) 5/6 on ground and minimizing the uncertainty/risk of such technologies/systems with respect to its operational use. Description and video demonstration of some ADR applicable test case/s using GMV's platform-art ® dynamic test facility will be included. Particular attention will be paid on the needed type of structural/functional active ADR vehicle and debris mock-ups, force/torque measurement and feedback capability over debris contact or momentum exchange actions, ground gravity

  1. Cognitive Virtualization: Combining Cognitive Models and Virtual Environments

    Energy Technology Data Exchange (ETDEWEB)

    Tuan Q. Tran; David I. Gertman; Donald D. Dudenhoeffer; Ronald L. Boring; Alan R. Mecham

    2007-08-01

    3D manikins are often used in visualizations to model human activity in complex settings. Manikins assist in developing understanding of human actions, movements and routines in a variety of different environments representing new conceptual designs. One such environment is a nuclear power plant control room, here they have the potential to be used to simulate more precise ergonomic assessments of human work stations. Next generation control rooms will pose numerous challenges for system designers. The manikin modeling approach by itself, however, may be insufficient for dealing with the desired technical advancements and challenges of next generation automated systems. Uncertainty regarding effective staffing levels; and the potential for negative human performance consequences in the presence of advanced automated systems (e.g., reduced vigilance, poor situation awareness, mistrust or blind faith in automation, higher information load and increased complexity) call for further research. Baseline assessment of novel control room equipment(s) and configurations needs to be conducted. These design uncertainties can be reduced through complementary analysis that merges ergonomic manikin models with models of higher cognitive functions, such as attention, memory, decision-making, and problem-solving. This paper will discuss recent advancements in merging a theoretical-driven cognitive modeling framework within a 3D visualization modeling tool to evaluate of next generation control room human factors and ergonomic assessment. Though this discussion primary focuses on control room design, the application for such a merger between 3D visualization and cognitive modeling can be extended to various areas of focus such as training and scenario planning.

  2. Cognitive Virtualization: Combining Cognitive Models and Virtual Environments

    International Nuclear Information System (INIS)

    Tuan Q. Tran; David I. Gertman; Donald D. Dudenhoeffer; Ronald L. Boring; Alan R. Mecham

    2007-01-01

    3D manikins are often used in visualizations to model human activity in complex settings. Manikins assist in developing understanding of human actions, movements and routines in a variety of different environments representing new conceptual designs. One such environment is a nuclear power plant control room, here they have the potential to be used to simulate more precise ergonomic assessments of human work stations. Next generation control rooms will pose numerous challenges for system designers. The manikin modeling approach by itself, however, may be insufficient for dealing with the desired technical advancements and challenges of next generation automated systems. Uncertainty regarding effective staffing levels; and the potential for negative human performance consequences in the presence of advanced automated systems (e.g., reduced vigilance, poor situation awareness, mistrust or blind faith in automation, higher information load and increased complexity) call for further research. Baseline assessment of novel control room equipment(s) and configurations needs to be conducted. These design uncertainties can be reduced through complementary analysis that merges ergonomic manikin models with models of higher cognitive functions, such as attention, memory, decision-making, and problem-solving. This paper will discuss recent advancements in merging a theoretical-driven cognitive modeling framework within a 3D visualization modeling tool to evaluate of next generation control room human factors and ergonomic assessment. Though this discussion primary focuses on control room design, the application for such a merger between 3D visualization and cognitive modeling can be extended to various areas of focus such as training and scenario planning

  3. A simple hyperbolic model for communication in parallel processing environments

    Science.gov (United States)

    Stoica, Ion; Sultan, Florin; Keyes, David

    1994-01-01

    We introduce a model for communication costs in parallel processing environments called the 'hyperbolic model,' which generalizes two-parameter dedicated-link models in an analytically simple way. Dedicated interprocessor links parameterized by a latency and a transfer rate that are independent of load are assumed by many existing communication models; such models are unrealistic for workstation networks. The communication system is modeled as a directed communication graph in which terminal nodes represent the application processes that initiate the sending and receiving of the information and in which internal nodes, called communication blocks (CBs), reflect the layered structure of the underlying communication architecture. The direction of graph edges specifies the flow of the information carried through messages. Each CB is characterized by a two-parameter hyperbolic function of the message size that represents the service time needed for processing the message. The parameters are evaluated in the limits of very large and very small messages. Rules are given for reducing a communication graph consisting of many to an equivalent two-parameter form, while maintaining an approximation for the service time that is exact in both large and small limits. The model is validated on a dedicated Ethernet network of workstations by experiments with communication subprograms arising in scientific applications, for which a tight fit of the model predictions with actual measurements of the communication and synchronization time between end processes is demonstrated. The model is then used to evaluate the performance of two simple parallel scientific applications from partial differential equations: domain decomposition and time-parallel multigrid. In an appropriate limit, we also show the compatibility of the hyperbolic model with the recently proposed LogP model.

  4. Dynamics and control for contactless interaction between spacecraft and tumbling debris

    Science.gov (United States)

    Li, Haiyang; Li, Jingyang; Jiang, Fanghua

    2018-01-01

    Tumbling debris has become a great threat to orbit activities. Contactless interaction is a novel concept for active debris removal, through which the tumbling debris no longer rotates freely but is under control. The contactless interaction method aims to de-tumble the debris and then maintain desired relative states between the spacecraft and debris. The spacecraft is simultaneously stabilized through three-axis attitude control, which makes the de-tumbling and capture operation much safer, more effective and accurate. The dynamics and control for the contactless interaction have been little studied in the past years. This paper considers a generic dynamics and control problem for contactless interaction between a spacecraft and debris. A translational and rotational dynamics model of contactless interaction is proposed and the 6-DOF equations are established. The contactless interaction control law is designed with the backstepping method, and the spacecraft three-axis control law is designed with the PD control. Simulation results show that the angular momentum is transferred from the debris to the spacecraft and the debris is thus de-tumbled. The desired relative states are achieved efficiently. Significantly, the spacecraft and debris no longer rotate in the inertial frame and, hence, the safety and accuracy for capture operation are guaranteed.

  5. Strategic management in urban environment using SWOT and QSPM model

    Directory of Open Access Journals (Sweden)

    M. Pazouki

    2017-04-01

    Full Text Available Sustainable urban development is a new concept of fundamental environmental metropolitan management that not only creates the demand for changing the concepts of economic development, but also affects social development. The current study  provides  a conceptual model of a sustainable environment pattern In District 22 of Tehran that depends on the relationship between environment and economy, and a network of urban function, which  Included transport infrastructure and community centers and economic and regional level in support of the ecological services in Tehran. This landscape often  had discrepancies  with the development of the city between the layers and the creation of ecological fragile areas. The main objective of the study was to determine the sustainability indicators and create a future development  model  for District 22 of Tehran. The data was collected by having a review of similar studies and field research on the subject and therefore the effective factors were identified. After accomplished proceedings, the questionnaire was prepared and the results were used in SWOT charts' grading after analyzing at interior and exterior matrix. Ultimately, quantitative strategic planning matrix (QSPM was performed based on the results and analysis. This process provided a comprehensive model for sustainable urban development as sustainable development urban landscape pattern.

  6. Study on geological environment model using geostatistics method

    International Nuclear Information System (INIS)

    Honda, Makoto; Suzuki, Makoto; Sakurai, Hideyuki; Iwasa, Kengo; Matsui, Hiroya

    2005-03-01

    The purpose of this study is to develop the geostatistical procedure for modeling geological environments and to evaluate the quantitative relationship between the amount of information and the reliability of the model using the data sets obtained in the surface-based investigation phase (Phase 1) of the Horonobe Underground Research Laboratory Project. This study lasts for three years from FY2004 to FY2006 and this report includes the research in FY2005 as the second year of three-year study. In FY2005 research, the hydrogeological model was built as well as FY2004 research using the data obtained from the deep boreholes (HDB-6, 7 and 8) and the ground magnetotelluric (AMT) survey which were executed in FY2004 in addition to the data sets used in the first year of study. Above all, the relationship between the amount of information and the reliability of the model was demonstrated through a comparison of the models at each step which corresponds to the investigation stage in each FY. Furthermore, the statistical test was applied for detecting the difference of basic statistics of various data due to geological features with a view to taking the geological information into the modeling procedures. (author)

  7. Animal model for schizophrenia that reflects gene-environment interactions.

    Science.gov (United States)

    Nagai, Taku; Ibi, Daisuke; Yamada, Kiyofumi

    2011-01-01

    Schizophrenia is a devastating psychiatric disorder that impairs mental and social functioning and affects approximately 1% of the population worldwide. Genetic susceptibility factors for schizophrenia have recently been reported, some of which are known to play a role in neurodevelopment; these include neuregulin-1, dysbindin, and disrupted-in-schizophrenia 1 (DISC1). Moreover, epidemiologic studies suggest that environmental insults, such as prenatal infection and perinatal complication, are involved in the development of schizophrenia. The possible interaction between environment and genetic susceptibility factors, especially during neurodevelopment, is proposed as a promising disease etiology of schizophrenia. Polyriboinosinic-polyribocytidilic acid (polyI : C) is a synthetic analogue of double-stranded RNA that leads to the pronounced but time-limited production of pro-inflammatory cytokines. Maternal immune activation by polyI : C exposure in rodents is known to precipitate a wide spectrum of behavioral, cognitive, and pharmacological abnormalities in adult offspring. Recently, we have reported that neonatal injection of polyI : C in mice results in schizophrenia-like behavioral alterations in adulthood. In this review, we show how gene-environment interactions during neurodevelopment result in phenotypic changes in adulthood by injecting polyI : C into transgenic mice that express a dominant-negative form of human DISC1 (DN-DISC1). Our findings suggest that polyI : C-treated DN-DISC1 mice are a well-validated animal model for schizophrenia that reflects gene-environment interactions.

  8. Application of simulation technique on debris flow hazard zone delineation: a case study in the Daniao tribe, Eastern Taiwan

    Directory of Open Access Journals (Sweden)

    M. P. Tsai

    2011-11-01

    Full Text Available Typhoon Morakot struck Taiwan in August 2009 and induced considerable disasters, including large-scale landslides and debris flows. One of these debris flows was experienced by the Daniao tribe in Taitung, Eastern Taiwan. The volume was in excess of 500 000 m3, which was substantially larger than the original design mitigation capacity. This study considered large-scale debris flow simulations in various volumes at the same area by using the DEBRIS-2D numerical program. The program uses the generalized Julien and Lan (1991 rheological model to simulate debris flows. In this paper, the sensitivity factor considered on the debris flow spreading is the amount of the debris flow initial volume. These simulated results in various amounts of debris flow initial volume demonstrated that maximal depths of debris flows were almost deposited in the same area, and also revealed that a 20% variation in estimating the amount of total volume at this particular site results in a 2.75% variation on the final front position. Because of the limited watershed terrain, the hazard zones of debris flows were not expanded. Therefore, the amount of the debris flow initial volume was not sensitive.

  9. Environment

    Science.gov (United States)

    2005-01-01

    biodiversity. Consequently, the major environmental challenges facing us in the 21st century include: global climate change , energy, population and food...technological prowess, and security interests. Challenges Global Climate Change – Evidence shows that our environment and the global climate ... urbanization will continue to pressure the regional environment . Although most countries have environmental protection ministries or agencies, a lack of

  10. Simscape Modeling Verification in the Simulink Development Environment

    Science.gov (United States)

    Volle, Christopher E. E.

    2014-01-01

    The purpose of the Simulation Product Group of the Control and Data Systems division of the NASA Engineering branch at Kennedy Space Center is to provide a realtime model and simulation of the Ground Subsystems participating in vehicle launching activities. The simulation software is part of the Spaceport Command and Control System (SCCS) and is designed to support integrated launch operation software verification, and console operator training. Using Mathworks Simulink tools, modeling engineers currently build models from the custom-built blocks to accurately represent ground hardware. This is time consuming and costly due to required rigorous testing and peer reviews to be conducted for each custom-built block. Using Mathworks Simscape tools, modeling time can be reduced since there would be no custom-code developed. After careful research, the group came to the conclusion it is feasible to use Simscape's blocks in MatLab's Simulink. My project this fall was to verify the accuracy of the Crew Access Arm model developed using Simscape tools running in the Simulink development environment.

  11. Mathematical modeling in economics, ecology and the environment

    CERN Document Server

    Hritonenko, Natali

    2013-01-01

    Updated to textbook form by popular demand, this second edition discusses diverse mathematical models used in economics, ecology, and the environmental sciences with emphasis on control and optimization. It is intended for graduate and upper-undergraduate course use, however, applied mathematicians, industry practitioners, and a vast number of interdisciplinary academics will find the presentation highly useful. Core topics of this text are: ·         Economic growth and technological development ·         Population dynamics and human impact on the environment ·         Resource extraction and scarcity ·         Air and water contamination ·         Rational management of the economy and environment ·         Climate change and global dynamics The step-by-step approach taken is problem-based and easy to follow. The authors aptly demonstrate that the same models may be used to describe different economic and environmental processes and that similar invest...

  12. A PRIMER ON UNIFYING DEBRIS DISK MORPHOLOGIES

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eve J.; Chiang, Eugene, E-mail: evelee@berkeley.edu, E-mail: echiang@astro.berkeley.edu [Department of Astronomy, University of California Berkeley, Berkeley, CA 94720-3411 (United States)

    2016-08-20

    A “minimum model” for debris disks consists of a narrow ring of parent bodies, secularly forced by a single planet on a possibly eccentric orbit, colliding to produce dust grains that are perturbed by stellar radiation pressure. We demonstrate how this minimum model can reproduce a wide variety of disk morphologies imaged in scattered starlight. Five broad categories of disk shape can be captured: “rings,” “needles,” “ships-and-wakes,” “bars,” and “moths (a.k.a. fans),” depending on the viewing geometry. Moths can also sport “double wings.” We explain the origin of morphological features from first principles, exploring the dependence on planet eccentricity, disk inclination dispersion, and the parent body orbital phases at which dust grains are born. A key determinant in disk appearance is the degree to which dust grain orbits are apsidally aligned. Our study of a simple steady-state (secularly relaxed) disk should serve as a reference for more detailed models tailored to individual systems. We use the intuition gained from our guidebook of disk morphologies to interpret, informally, the images of a number of real-world debris disks. These interpretations suggest that the farthest reaches of planetary systems are perturbed by eccentric planets, possibly just a few Earth masses each.

  13. A PRIMER ON UNIFYING DEBRIS DISK MORPHOLOGIES

    International Nuclear Information System (INIS)

    Lee, Eve J.; Chiang, Eugene

    2016-01-01

    A “minimum model” for debris disks consists of a narrow ring of parent bodies, secularly forced by a single planet on a possibly eccentric orbit, colliding to produce dust grains that are perturbed by stellar radiation pressure. We demonstrate how this minimum model can reproduce a wide variety of disk morphologies imaged in scattered starlight. Five broad categories of disk shape can be captured: “rings,” “needles,” “ships-and-wakes,” “bars,” and “moths (a.k.a. fans),” depending on the viewing geometry. Moths can also sport “double wings.” We explain the origin of morphological features from first principles, exploring the dependence on planet eccentricity, disk inclination dispersion, and the parent body orbital phases at which dust grains are born. A key determinant in disk appearance is the degree to which dust grain orbits are apsidally aligned. Our study of a simple steady-state (secularly relaxed) disk should serve as a reference for more detailed models tailored to individual systems. We use the intuition gained from our guidebook of disk morphologies to interpret, informally, the images of a number of real-world debris disks. These interpretations suggest that the farthest reaches of planetary systems are perturbed by eccentric planets, possibly just a few Earth masses each.

  14. A Primer on Unifying Debris Disk Morphologies

    Science.gov (United States)

    Lee, Eve J.; Chiang, Eugene

    2016-08-01

    A “minimum model” for debris disks consists of a narrow ring of parent bodies, secularly forced by a single planet on a possibly eccentric orbit, colliding to produce dust grains that are perturbed by stellar radiation pressure. We demonstrate how this minimum model can reproduce a wide variety of disk morphologies imaged in scattered starlight. Five broad categories of disk shape can be captured: “rings,” “needles,” “ships-and-wakes,” “bars,” and “moths (a.k.a. fans),” depending on the viewing geometry. Moths can also sport “double wings.” We explain the origin of morphological features from first principles, exploring the dependence on planet eccentricity, disk inclination dispersion, and the parent body orbital phases at which dust grains are born. A key determinant in disk appearance is the degree to which dust grain orbits are apsidally aligned. Our study of a simple steady-state (secularly relaxed) disk should serve as a reference for more detailed models tailored to individual systems. We use the intuition gained from our guidebook of disk morphologies to interpret, informally, the images of a number of real-world debris disks. These interpretations suggest that the farthest reaches of planetary systems are perturbed by eccentric planets, possibly just a few Earth masses each.

  15. Emerging insights into the dynamics of submarine debris flows

    Directory of Open Access Journals (Sweden)

    A. Elverhøi

    2005-01-01

    Full Text Available Recent experimental and theoretical work on the dynamics of submarine debris flows is summarized. Hydroplaning was first discovered in laboratory flows and later shown to likely occur in natural debris flows as well. It is a prime mechanism for explaining the extremely long runout distances observed in some natural debris flows even of over-consolidated clay materials. Moreover, the accelerations and high velocities reached by the flow head in a short time appear to fit well with the required initial conditions of observed tsunamis as obtained from back-calculations. Investigations of high-speed video recordings of laboratory debris flows were combined with measurements of total and pore pressure. The results are pointing towards yet another important role of ambient water: Water that intrudes from the water cushion underneath the hydroplaning head and through cracks in the upper surface of the debris flow may drastically soften initially stiff clayey material in the 'neck' of the flow, where significant stretching occurs due to the reduced friction at the bottom of the hydroplaning head. This self-reinforcing process may lead to the head separating from the main body and becoming an 'outrunner' block as clearly observed in several natural debris flows. Comparison of laboratory flows with different material composition indicates a gradual transition from hydroplaning plug flows of stiff clay-rich material, with a very low suspension rate, to the strongly agitated flow of sandy materials that develop a pronounced turbidity current. Statistical analysis of the great number of distinguishable lobes in the Storegga slide complex reveals power-law scaling behavior of the runout distance with the release mass over many orders of magnitude. Mathematical flow models based on viscoplastic material behavior (e.g. BING successfully reproduce the observed scaling behavior only for relatively small clay-rich debris flows while granular (frictional models

  16. Space Tourism: Orbital Debris Considerations

    Science.gov (United States)

    Mahmoudian, N.; Shajiee, S.; Moghani, T.; Bahrami, M.

    2002-01-01

    Space activities after a phase of research and development, political competition and national prestige have entered an era of real commercialization. Remote sensing, earth observation, and communication are among the areas in which this growing industry is facing competition and declining government money. A project like International Space Station, which draws from public money, has not only opened a window of real multinational cooperation, but also changed space travel from a mere fantasy into a real world activity. Besides research activities for sending man to moon and Mars and other outer planets, space travel has attracted a considerable attention in recent years in the form of space tourism. Four countries from space fairing nations are actively involved in the development of space tourism. Even, nations which are either in early stages of space technology development or just beginning their space activities, have high ambitions in this area. This is worth noting considering their limited resources. At present, trips to space are available, but limited and expensive. To move beyond this point to generally available trips to orbit and week long stays in LEO, in orbital hotels, some of the required basic transportations, living requirements, and technological developments required for long stay in orbit are already underway. For tourism to develop to a real everyday business, not only the price has to come down to meaningful levels, but also safety considerations should be fully developed to attract travelers' trust. A serious hazard to space activities in general and space tourism in particular is space debris in earth orbit. Orbiting debris are man-made objects left over by space operations, hazardous to space missions. Since the higher density of debris population occurs in low earth orbit, which is also the same orbit of interest to space tourism, a careful attention should be paid to the effect of debris on tourism activities. In this study, after a

  17. ANALYSIS OF DEBRIS FLOW BEHAVIOR USING AIRBORNE LIDAR AND IMAGE DATA

    Directory of Open Access Journals (Sweden)

    G. Kim

    2016-06-01

    Full Text Available The frequency of debris flow events caused by severe rainstorms has increased in Korea. LiDAR provides high-resolution topographical data that can represent the land surface more effectively than other methods. This study describes the analysis of geomorphologic changes using digital surface models derived from airborne LiDAR and aerial image data acquired before and after a debris flow event in the southern part of Seoul, South Korea in July 2011. During this event, 30 houses were buried, 116 houses were damaged, and 22 human casualties were reported. Longitudinal and cross-sectional profiles of the debris flow path reconstructed from digital surface models were used to analyze debris flow behaviors such as landslide initiation, transport, erosion, and deposition. LiDAR technology integrated with GIS is a very useful tool for understanding debris flow behavior.

  18. Analysis of Debris Flow Behavior Using Airborne LIDAR and Image Data

    Science.gov (United States)

    Kim, G.; Yune, C. Y.; Paik, J.; Lee, S. W.

    2016-06-01

    The frequency of debris flow events caused by severe rainstorms has increased in Korea. LiDAR provides high-resolution topographical data that can represent the land surface more effectively than other methods. This study describes the analysis of geomorphologic changes using digital surface models derived from airborne LiDAR and aerial image data acquired before and after a debris flow event in the southern part of Seoul, South Korea in July 2011. During this event, 30 houses were buried, 116 houses were damaged, and 22 human casualties were reported. Longitudinal and cross-sectional profiles of the debris flow path reconstructed from digital surface models were used to analyze debris flow behaviors such as landslide initiation, transport, erosion, and deposition. LiDAR technology integrated with GIS is a very useful tool for understanding debris flow behavior.

  19. On the quantity and composition of floating plastic debris entering and leaving the Tamar Estuary, Southwest England.

    Science.gov (United States)

    Sadri, Saeed S; Thompson, Richard C

    2014-04-15

    The majority of plastic debris found in the marine environment has land based sources and rivers are considered an important medium for transfer of this debris. Here we report on the quantity and composition of floating plastic debris collected from surface waters of the Tamar Estuary. This represents the first study of riverine transport of floating plastic debris into European waters during different tidal regimes. Plastics were found in a variety of forms and sizes and microplastics (debris. The most abundant types of plastic were Polyethylene (40%), Polystyrene (25%) and Polypropylene (19%). There was a significant difference in size frequency distribution between the spring and neap tides with more fragments of larger size observed during spring tides. While it is clear that debris has accumulated on shorelines within the estuary, during our study this river did not identify as a net source or sink. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

  20. Debris flow grain size scales with sea surface temperature over glacial-interglacial timescales

    Science.gov (United States)

    D'Arcy, Mitch; Roda Boluda, Duna C.; Whittaker, Alexander C.; Araújo, João Paulo C.

    2015-04-01

    Debris flows are common erosional processes responsible for a large volume of sediment transfer across a range of landscapes from arid settings to the tropics. They are also significant natural hazards in populated areas. However, we lack a clear set of debris flow transport laws, meaning that: (i) debris flows remain largely neglected by landscape evolution models; (ii) we do not understand the sensitivity of debris flow systems to past or future climate changes; and (iii) it remains unclear how to interpret debris flow stratigraphy and sedimentology, for example whether their deposits record information about past tectonics or palaeoclimate. Here, we take a grain size approach to characterising debris flow deposits from 35 well-dated alluvial fan surfaces in Owens Valley, California. We show that the average grain sizes of these granitic debris flow sediments precisely scales with sea surface temperature throughout the entire last glacial-interglacial cycle, increasing by ~ 7 % per 1 ° C of climate warming. We compare these data with similar debris flow systems in the Mediterranean (southern Italy) and the tropics (Rio de Janeiro, Brazil), and find equivalent signals over a total temperature range of ~ 14 ° C. In each area, debris flows are largely governed by rainfall intensity during triggering storms, which is known to increase exponentially with temperature. Therefore, we suggest that these debris flow systems are transporting predictably coarser-grained sediment in warmer, stormier conditions. This implies that debris flow sedimentology is governed by discharge thresholds and may be a sensitive proxy for past changes in rainfall intensity. Our findings show that debris flows are sensitive to climate changes over short timescales (≤ 104 years) and therefore highlight the importance of integrating hillslope processes into landscape evolution models, as well as providing new observational constraints to guide this. Finally, we comment on what grain size

  1. Plastic debris and policy: Using current scientific understanding to invoke positive change.

    Science.gov (United States)

    Rochman, Chelsea M; Cook, Anna-Marie; Koelmans, Albert A

    2016-07-01

    Captain Charles Moore introduced the world to the "Great Pacific Garbage Patch" in the mid-1990s, and images of plastic debris in the oceans began to sweep the media. Since then, there has been increasing interest from scientists, the public, and policy makers regarding plastic debris in the environment. Today, there remains no doubt that plastic debris contaminates aquatic (marine and freshwater) habitats and animals globally. The growing scientific evidence demonstrates widespread contamination from plastic debris, and researchers are beginning to understand the sources, fate, and effects of the material. As new scientific understanding breeds new questions, scientists are working to fill data gaps regarding the fate and effects of plastic debris and the mechanisms that drive these processes. In parallel, policy makers are working to mitigate this contamination. The authors focus on what is known about plastic debris that is relevant to policy by reviewing some of the weight of evidence regarding contamination, fate, and effects of the material. Moreover, they highlight some examples of how science has already been used to inform policy change and mitigation and discuss opportunities for future linkages between science and policy to continue the relationship and contribute to effective solutions for plastic debris. Environ Toxicol Chem 2016;35:1617-1626. © 2016 SETAC. © 2016 SETAC.

  2. A Formal Framework for Integrated Environment Modeling Systems

    Directory of Open Access Journals (Sweden)

    Gaofeng Zhang

    2017-02-01

    Full Text Available Integrated Environment Modeling (IEM has become more and more important for environmental studies and applications. IEM systems have also been extended from scientific studies to much wider practical application situations. The quality and improved efficiency of IEM systems have therefore become increasingly critical. Although many advanced and creative technologies have been adopted to improve the quality of IEM systems, there is scarcely any formal method for evaluating and improving them. This paper is devoted to proposing a formal method to improve the quality and the developing efficiency of IEM systems. Two primary contributions are made. Firstly, a formal framework for IEM is proposed. The framework not only reflects the static and dynamic features of IEM but also covers different views from variant roles throughout the IEM lifecycle. Secondly, the formal operational semantics corresponding to the former model of the IEM is derived in detail; it can be used as the basis for aiding automated integrated modeling and verifying the integrated model.

  3. Reduction of CO2 and orbital debris: can CO2 emission trading principles be applied to debris reduction?

    Science.gov (United States)

    Orlando, Giovanni; Kinnersley, Mark; Starke, Juergen; Hugel, Sebastian; Hartner, Gloria; Singh, Sanjay; Loubiere, Vincent; Staebler, Dominik-Markus; O'Brien-Organ, Christopher; Schwindt, Stefan; Serreau, Francois; Sharma, Mohit

    In the past years global pollution and the specific situation of global warming changes have been strongly influencing public opinion and thus obliged politicians to initiate/ negotiate in-ternational agreements to control, avoid or at least reduce the impact of CO2 emissions e.g. The Kyoto Protocol (1997) and the International Copenhagen conference on Climate Change (2009). In the orbital debris area the collision between the Iridium33 and Cosmos 2251 satel-lites in 2009 has again pushed to the forefront the discussion of the space pollution by space debris and the increasing risk of critical and catastrophic events during the nominal life time of space objects. It is shown by simulations that for Low Earth Orbits the critical debris situation is already achieved and the existing space objects will probably produce sufficient space debris elements -big enough -to support the cascade effect (Kessler Syndrome). In anal-ogy with CO2 emissions, potential recommendations / regulations to reduce the production of Space Debris or its permanence in orbit, are likely to open new markets involving Miti-gation and Removal of Space Debris. The principle approach for the CO2 emission trading model will be investigated and the applicability for the global space debris handling will be analysed. The major differences of the two markets will be derived and the consequences in-dicated. Potential alternative solutions will be proposed and discussed. For the example of the CO2 emission trading principles within EU and worldwide legal conditions for space debris (national / international laws and recommendations) will be considered as well as the commer-cial approach from the controlled situation of dedicated orders to a free / competitive market in steps. It is of interest to consider forms of potential industrial organisations and interna-tional co-operations to react on a similar architecture for the debris removal trading including incentives and penalties for the different

  4. A short-term experiment on sub-debris melt on highly maritime Franz Josef Glacier, Southern Alps, New Zealand

    Science.gov (United States)

    Hagg, Wilfried; Brook, Martin; Mayer, Christoph; Winkler, Stefan

    2013-04-01

    Melt rates of glacier ice underneath a debris cover are dependent on the energy transfer through the debris cover. The effective heat conduction through the debris material wich is the major source of melt energy might be influenced by a number of processes, like air or water advection in the pore space of the debris material. In order to examine the potential contribution of individual parameters on ice melt we placed an ablation stake into a hand-drilled hole below 24 cm of supraglacial debris cover on the lower part of Franz Josef Glacier. Three thermistors were installed at the stake at depths of 6 cm, 12 cm and 18 cm below the debris surface, ensuring equal vertical distances between debris surface, individual thermistors and the debris-ice interface. The results show the expected and distinct diurnal temperature variation and a decreasing amplitude with depth. Melt rates were calculated assuming that conductive heat flux is the only energy source. Although heavy precipitation occurred on one day during the experiment, the observed melt agreed well with calculated values for dry conditions. This suggests that even in this highly maritime environment, additional energy provided by percolating rain is of minor importance for sub-debris melt. As a consequence, ablation beneath debris is mainly controlled by sensible heat flux and shortwave radiation. Both factors are closely related to air temperature. This is probably one reason why air temperature is a strong predictor of melt under debris and the degree day approach usually works well also for debris covered glacier parts. These findings will be of importance in the future with larger proportions of the glacier tongue expected to become successively covered by debris

  5. Current and Future Impact Risks from Small Debris to Operational Satellites

    Science.gov (United States)

    Liou, Jer-Chyi; Kessler, Don

    2011-01-01

    The collision between Iridium 33 and Cosmos 2251 in 2009 signaled the potential onset of the collision cascade effect, commonly known as the "Kessler Syndrome", in the low Earth orbit (LEO) region. Recent numerical simulations have shown that the 10 cm and larger debris population in LEO will continue to increase even with a good implementation of the commonly-adopted mitigation measures. This increase is driven by collisions involving large and massive intacts, i.e., rocket bodies and spacecraft. Therefore, active debris removal (ADR) of large and massive intacts with high collision probabilities has been argued as a direct and effective means to remediate the environment in LEO. The major risk for operational satellites in the environment, however, comes from impacts with debris just above the threshold of the protection shields. In general, these are debris in the millimeter to centimeter size regime. Although impacts by these objects are insufficient to lead to catastrophic breakup of the entire vehicle, the damage is certainly severe enough to cause critical failure of the key instruments or the entire payload. The focus of this paper is to estimate the impact risks from 5 mm and 1 cm debris to active payloads in LEO (1) in the current environment and (2) in the future environment based on different projection scenarios, including ADR. The goal of the study is to quantify the benefits of ADR in reducing debris impact risks to operational satellites.

  6. Self-leveling onset criteria in debris beds

    International Nuclear Information System (INIS)

    Zhang, Bin; Harada, Tetsushi; Hirahara, Daisuke; Matsumoto, Tatsuya; Morita, Koji; Fukuda, Kenji; Yamano, Hidemasa; Suzuki, Tohru; Tobita, Yoshiharu

    2010-01-01

    In a core-disruptive accident of a sodium-cooled fast breeder reactor, core debris may settle on the core-support structure and/or in the lower inlet plenum of the reactor vessel because of rapid quenching and fragmentation of molten core materials in the subcooled sodium plenum. Coolant boiling is the mechanism driving the self-leveling of a debris bed that causes significant changes in the heat-removal capability of the beds. In the present study, we develop criteria establishing the onset of this self-leveling behavior that we base on a force balance model assuming a debris bed with a single-sized spherical particle. The model considers drag, buoyancy, and gravity acting on each particle. A series of experiments with simulant materials verified the applicability of this description of self-leveling. Particle size (between 0.5-6 mm), shape (spherical and nonspherical), density (namely of alumina, zirconia, lead, and stainless steel), along with boiling intensity, bed volume, and even experimental methods were taken into consideration to obtain general characteristics of the self-leveling process. We decided to use depressurization boiling to simulate an axially increasing void distribution in the debris bed, although bottom heating was also used to validate the use of the depressurization method. On the self-leveling onset issues, we obtained good agreement between model predictions and experimental results. Extrapolation of our model to actual reactor conditions is discussed. (author)

  7. The Parental Environment Cluster Model of Child Neglect: An Integrative Conceptual Model.

    Science.gov (United States)

    Burke, Judith; Chandy, Joseph; Dannerbeck, Anne; Watt, J. Wilson

    1998-01-01

    Presents Parental Environment Cluster model of child neglect which identifies three clusters of factors involved in parents' neglectful behavior: (1) parenting skills and functions; (2) development and use of positive social support; and (3) resource availability and management skills. Model offers a focal theory for research, structure for…

  8. Behavior of explosion debris clouds

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    In the normal course of events the behavior of debris clouds created by explosions will be of little concern to the atomic energy industry. However, two situations, one of them actual and one postulated, exist where the rise and spread of explosion clouds can affect site operations. The actual occurrence would be the detonation of nuclear weapons and the resultant release and transport of radioactive debris across the various atomic energy installations. Although the activity of the diffusing cloud is not of biological concern, it may still be sufficiently above background to play havoc with the normal readings of sensitive monitoring instruments. If it were not known that these anomalous readings resulted from explosion debris, considerable time and expense might be required for on-site testing and tracing. Fortunately it is usually possible, with the use of meteorological data and forecasts, to predict when individual sites are affected by nuclear weapon debris effects. The formation rise, and diffusion of weapon clouds will be discussed. The explosion of an atomic reactor is the postulated situation. It is common practice in reactor hazard analysis to assume a combination of circumstances which might result in a nuclear incident with a release of material to the atmosphere. It is not within the scope of this report to examine the manifold plausibilities that might lead to an explosion or the possible methods of release of gaseous and/or particulates from such an occurrence. However, if the information of a cloud is assumed and some idea of its energy content is obtainable, estimates of the cloud behavior in the atmosphere can be made

  9. RHIC/AGS Online Model Environments: Experiences and Design for AGS Modeling

    International Nuclear Information System (INIS)

    Brown, K.; Niederer, J.; Satogata, T.; Alai Tafti, A.; Tsoupas, N.; Zeijts, J. van

    1999-01-01

    The RHIC/AGS online modeling environment, a general client-server modeling package that supports cdev and straightforward integration of diverse computational modeling engines (CMEs), is being adapted to model the AGS and Booster at BNL. This implementation uses a version of MAD modified at BNL that allows traditional lattice structure analysis, single pass beam line analysis, multi-particle tracking, interactive graphics, and the use of field maps. The on-line model system is still under development, a real working prototype exists and is being tested. This paper describes the system and experience with its design and use for AGS and AGS Booster online modeling

  10. Space Environment Modelling with the Use of Artificial Intelligence Methods

    Science.gov (United States)

    Lundstedt, H.; Wintoft, P.; Wu, J.-G.; Gleisner, H.; Dovheden, V.

    1996-12-01

    Space based technological systems are affected by the space weather in many ways. Several severe failures of satellites have been reported at times of space storms. Our society also increasingly depends on satellites for communication, navigation, exploration, and research. Predictions of the conditions in the satellite environment have therefore become very important. We will here present predictions made with the use of artificial intelligence (AI) techniques, such as artificial neural networks (ANN) and hybrids of AT methods. We are developing a space weather model based on intelligence hybrid systems (IHS). The model consists of different forecast modules, each module predicts the space weather on a specific time-scale. The time-scales range from minutes to months with the fundamental time-scale of 1-5 minutes, 1-3 hours, 1-3 days, and 27 days. Solar and solar wind data are used as input data. From solar magnetic field measurements, either made on the ground at Wilcox Solar Observatory (WSO) at Stanford, or made from space by the satellite SOHO, solar wind parameters can be predicted and modelled with ANN and MHD models. Magnetograms from WSO are available on a daily basis. However, from SOHO magnetograms will be available every 90 minutes. SOHO magnetograms as input to ANNs will therefore make it possible to even predict solar transient events. Geomagnetic storm activity can today be predicted with very high accuracy by means of ANN methods using solar wind input data. However, at present real-time solar wind data are only available during part of the day from the satellite WIND. With the launch of ACE in 1997, solar wind data will on the other hand be available during 24 hours per day. The conditions of the satellite environment are not only disturbed at times of geomagnetic storms but also at times of intense solar radiation and highly energetic particles. These events are associated with increased solar activity. Predictions of these events are therefore

  11. Exploiting Maximum Entropy method and ASTER data for assessing debris flow and debris slide susceptibility for the Giampilieri catchment (north-eastern Sicily, Italy).

    KAUST Repository

    Lombardo, Luigi

    2016-07-18

    This study aims at evaluating the performance of the Maximum Entropy method in assessing landslide susceptibility, exploiting topographic and multispectral remote sensing predictors. We selected the catchment of the Giampilieri stream, which is located in the north-eastern sector of Sicily (southern Italy), as test site. On 1/10/2009, a storm rainfall triggered in this area hundreds of debris flow/avalanche phenomena causing extensive economical damage and loss of life. Within this area a presence-only-based statistical method was applied to obtain susceptibility models capable of distinguish future activation sites of debris flow and debris slide, which where the main source failure mechanisms for flow or avalanche type propagation. The set of predictors used in this experiment comprised primary and secondary topographic attributes, derived by processing a high resolution digital elevation model, CORINE land cover data and a set of vegetation and mineral indices obtained by processing multispectral ASTER images. All the selected data sources are dated before the disaster. A spatially random partition technique was adopted for validation, generating fifty replicates for each of the two considered movement typologies in order to assess accuracy, precision and reliability of the models. The debris slide and debris flow susceptibility models produced high performances with the first type being the best fitted. The evaluation of the probability estimates around the mean value for each mapped pixel shows an inverted relation, with the most robust models corresponding to the debris flows. With respect to the role of each predictor within the modelling phase, debris flows appeared to be primarily controlled by topographic attributes whilst the debris slides were better explained by remotely sensed derived indices, particularly by the occurrence of previous wildfires across the slope. The overall excellent performances of the two models suggest promising perspectives for

  12. Exascale Co-design for Modeling Materials in Extreme Environments

    Energy Technology Data Exchange (ETDEWEB)

    Germann, Timothy C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-08

    Computational materials science has provided great insight into the response of materials under extreme conditions that are difficult to probe experimentally. For example, shock-induced plasticity and phase transformation processes in single-crystal and nanocrystalline metals have been widely studied via large-scale molecular dynamics simulations, and many of these predictions are beginning to be tested at advanced 4th generation light sources such as the Advanced Photon Source (APS) and Linac Coherent Light Source (LCLS). I will describe our simulation predictions and their recent verification at LCLS, outstanding challenges in modeling the response of materials to extreme mechanical and radiation environments, and our efforts to tackle these as part of the multi-institutional, multi-disciplinary Exascale Co-design Center for Materials in Extreme Environments (ExMatEx). ExMatEx has initiated an early and deep collaboration between domain (computational materials) scientists, applied mathematicians, computer scientists, and hardware architects, in order to establish the relationships between algorithms, software stacks, and architectures needed to enable exascale-ready materials science application codes within the next decade. We anticipate that we will be able to exploit hierarchical, heterogeneous architectures to achieve more realistic large-scale simulations with adaptive physics refinement, and are using tractable application scale-bridging proxy application testbeds to assess new approaches and requirements. Such current scale-bridging strategies accumulate (or recompute) a distributed response database from fine-scale calculations, in a top-down rather than bottom-up multiscale approach.

  13. AN INCLUSIVE APPROACH TO ONLINE LEARNING ENVIRONMENTS: Models and Resources

    Directory of Open Access Journals (Sweden)

    Aline Germain-RUTHERFORD

    2008-04-01

    Full Text Available The impact of ever-increasing numbers of online courses on the demographic composition of classes has meant that the notions of diversity, multiculturality and globalization are now key aspects of curriculum planning. With the internationalization and globalization of education, and faced with rising needs for an increasingly educated and more adequately trained workforce, universities are offering more flexible programs, assisted by new educational and communications technologies. Faced with this diversity of populations and needs, many instructors are becoming aware of the importance of addressing the notions of multiculturality and interculturality in the design of online however this raises many questions. For example, how do we integrate and address this multicultural dimension in a distance education course aimed at students who live in diverse cultural environments? How do the challenges of intercultural communication in an online environment affect online teaching and learning? What are the characteristics of an online course that is inclusive of all types of diversity, and what are the guiding principles for designing such courses? We will attempt to answer some of these questions by first exploring the concepts of culture and learning cultures. This will help us to characterize the impact on online learning of particular cultural dimensions. We will then present and discuss different online instructional design models that are culturally inclusive, and conclude with the description of a mediated instructional training module on the management of the cultural dimension of online teaching and learning. This module is mainly addressed to teachers and designers of online courses.

  14. Communication Modeling in the Joint Integrated Mission Model (JIMM) and the Air Combat Environment Test & Evaluation Facility (ACETEF)

    National Research Council Canada - National Science Library

    Chapman, Michael D; Mutschler, David W

    2006-01-01

    The Joint Integrated Mission Model (JIMM) is a complex analytical model that provides the threat environment and main control for integrated operation of installed system test in the NAVAIR Air Combat Environment Test...

  15. Virtual building environments (VBE) - Applying information modeling to buildings

    Energy Technology Data Exchange (ETDEWEB)

    Bazjanac, Vladimir

    2004-06-21

    A Virtual Building Environment (VBE) is a ''place'' where building industry project staffs can get help in creating Building Information Models (BIM) and in the use of virtual buildings. It consists of a group of industry software that is operated by industry experts who are also experts in the use of that software. The purpose of a VBE is to facilitate expert use of appropriate software applications in conjunction with each other to efficiently support multidisciplinary work. This paper defines BIM and virtual buildings, and describes VBE objectives, set-up and characteristics of operation. It informs about the VBE Initiative and the benefits from a couple of early VBE projects.

  16. Expanding the modeling capabilities of the cognitive environment simulation

    International Nuclear Information System (INIS)

    Roth, E.M.; Mumaw, R.J.; Pople, H.E. Jr.

    1991-01-01

    The Nuclear Regulatory Commission has been conducting a research program to develop more effective tools to model the cognitive activities that underlie intention formation during nuclear power plant (NPP) emergencies. Under this program an artificial intelligence (AI) computer simulation called Cognitive Environment Simulation (CES) has been developed. CES simulates the cognitive activities involved in responding to a NPP accident situation. It is intended to provide an analytic tool for predicting likely human responses, and the kinds of errors that can plausibly arise under different accident conditions to support human reliability analysis. Recently CES was extended to handle a class of interfacing loss of coolant accidents (ISLOCAs). This paper summarizes the results of these exercises and describes follow-on work currently underway

  17. Lattice models of directed and semiflexible polymers in anisotropic environment

    International Nuclear Information System (INIS)

    Haydukivska, K; Blavatska, V

    2015-01-01

    We study the conformational properties of polymers in presence of extended columnar defects of parallel orientation. Two classes of macromolecules are considered: the so-called partially directed polymers with preferred orientation along direction of the external stretching field and semiflexible polymers. We are working within the frames of lattice models: partially directed self-avoiding walks (PDSAWs) and biased self-avoiding walks (BSAWs). Our numerical analysis of PDSAWs reveals, that competition between the stretching field and anisotropy caused by presence of extended defects leads to existing of three characteristic length scales in the system. At each fixed concentration of disorder we found a transition point, where the influence of extended defects is exactly counterbalanced by the stretching field. Numerical simulations of BSAWs in anisotropic environment reveal an increase of polymer stiffness. In particular, the persistence length of semiflexible polymers increases in presence of disorder. (paper)

  18. Representing the environment 3.0. Maps, models, networks.

    Directory of Open Access Journals (Sweden)

    Letizia Bollini

    2014-05-01

    Full Text Available Web 3.0 is changing the world we live and perceive the environment anthropomorphized, making a stratifation of levels of experience and mediated by the devices. If the urban landscape is designed, shaped and planned space, there is a social landscape that overwrite the territory of values, representations shared images, narratives of personal and collective history. Mobile technology introduces an additional parameter, a kind of non-place, which allows the coexistence of the here and elsewhere in an sort of digital landscape. The maps, mental models, the system of social networks become, then, the way to present, represented and represent themselves in a kind of ideal coring of the co-presence of levels of physical, cognitive and collective space.

  19. Influence of check dams on debris-flow run-out intensity

    Directory of Open Access Journals (Sweden)

    A. Remaître

    2008-12-01

    Full Text Available Debris flows are very dangerous phenomena claiming thousands of lives and millions of Euros each year over the world. Disaster mitigation includes non-structural (hazard mapping, insurance policies, active structural (drainage systems and passive structural (check dams, stilling basins countermeasures. Since over twenty years, many efforts are devoted by the scientific and engineering communities to the design of proper devices able to capture the debris-flow volume and/or break down the energy. If considerable theoretical and numerical work has been performed on the size, the shape and structure of check dams, allowing the definition of general design criteria, it is worth noting that less research has focused on the optimal location of these dams along the debris-flow pathway.

    In this paper, a methodological framework is proposed to evaluate the influence of the number and the location of the check dams on the reduction of the debris-flow intensity (in term of flow thickness, flow velocity and volume. A debris-flow model is used to simulate the run-out of the debris flow. The model uses the Janbu force diagram to resolve the force equilibrium equations; a bingham fluid rheology is introduced and represents the resistance term. The model has been calibrated on two muddy debris-flow events that occurred in 1996 and 2003 at the Faucon watershed (South French Alps.

    Influence of the check dams on the debris-flow intensity is quantified taking into account several check dams configurations (number and location as input geometrical parameters. Results indicate that debris-flow intensity is decreasing with the distance between the source area and the first check dams. The study demonstrates that a small number of check dams located near the source area may decrease substantially the debris-flow intensity on the alluvial fans.

  20. Emerge - A Python environment for the modeling of subsurface transfers

    Science.gov (United States)

    Lopez, S.; Smai, F.; Sochala, P.

    2014-12-01

    The simulation of subsurface mass and energy transfers often relies on specific codes that were mainly developed using compiled languages which usually ensure computational efficiency at the expense of relatively long development times and relatively rigid software. Even if a very detailed, possibly graphical, user-interface is developed the core numerical aspects are rarely accessible and the smallest modification will always need a compilation step. Thus, user-defined physical laws or alternative numerical schemes may be relatively difficult to use. Over the last decade, Python has emerged as a popular and widely used language in the scientific community. There already exist several libraries for the pre and post-treatment of input and output files for reservoir simulators (e.g. pytough). Development times in Python are considerably reduced compared to compiled languages, and programs can be easily interfaced with libraries written in compiled languages with several comprehensive numerical libraries that provide sequential and parallel solvers (e.g. PETSc, Trilinos…). The core objective of the Emerge project is to explore the possibility to develop a modeling environment in full Python. Consequently, we are developing an open python package with the classes/objects necessary to express, discretize and solve the physical problems encountered in the modeling of subsurface transfers. We heavily relied on Python to have a convenient and concise way of manipulating potentially complex concepts with a few lines of code and a high level of abstraction. Our result aims to be a friendly numerical environment targeting both numerical engineers and physicist or geoscientists with the possibility to quickly specify and handle geometries, arbitrary meshes, spatially or temporally varying properties, PDE formulations, boundary conditions…

  1. As main meal for sperm whales: plastics debris.

    Science.gov (United States)

    de Stephanis, Renaud; Giménez, Joan; Carpinelli, Eva; Gutierrez-Exposito, Carlos; Cañadas, Ana

    2013-04-15

    Marine debris has been found in marine animals since the early 20th century, but little is known about the impacts of the ingestion of debris in large marine mammals. In this study we describe a case of mortality of a sperm whale related to the ingestion of large amounts of marine debris in the Mediterranean Sea (4th published case worldwide to our knowledge), and discuss it within the context of the spatial distribution of the species and the presence of anthropogenic activities in the area that could be the source of the plastic debris found inside the sperm whale. The spatial distribution modelled for the species in the region shows that these animals can be seen in two distinct areas: near the waters of Almería, Granada and Murcia and in waters near the Strait of Gibraltar. The results shows how these animals feed in waters near an area completely flooded by the greenhouse industry, making them vulnerable to its waste products if adequate treatment of this industry's debris is not in place. Most types of these plastic materials have been found in the individual examined and cause of death was presumed to be gastric rupture following impaction with debris, which added to a previous problem of starvation. The problem of plastics arising from greenhouse agriculture should have a relevant section in the conservation plans and should be a recommendation from ACCOBAMS due to these plastics' and sperm whales' high mobility in the Mediterranean Sea. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Young Debris Disks With Newly Discovered Emission Features

    Science.gov (United States)

    Ballering, N.

    2014-04-01

    We analyzed the Spitzer/IRS spectra of young A and F stars that host debris disks with previously unidentified silicate emission features. Such features probe small, warm dust grains in the inner regions of these young systems where terrestrial planet formation may be proceeding (Lisse et al. 2009). For most systems, these regions are too near their host star to be directly seen with high-contrast imaging and too warm to be imaged with submillimeter interferometers. Mid-infrared excess spectra - originating from the thermal emission of the debris disk dust - remain the best data to constrain the properties of the debris in these regions. For each target, we fit physically-motivated model spectra to the data. Typical spectra of unresolved debris disks are featureless and suffer severe degeneracies between the dust location and the grain properties; however, spectra with solid-state emission features provide significantly more information, allowing for a more accurate determination of the dust size, composition, and location (e.g. Chen et al. 2006; Olofsson et al. 2012). Our results shed light on the dynamic properties occurring in the terrestrial regions of these systems. For instance, the sizes of the smallest grains and the nature of the grain size distribution reveal whether the dust originates from steady-state collisional cascades or from stochastic collisions. The properties of the dust grains - such as their crystalline or amorphous structure - can inform us of grain processing mechanisms in the disk. The location of this debris illuminates where terrestrial planet forming activity is occurring. We used results from the Beta Pictoris - which has a well-resolved debris disk with emission features (Li et al. 2012) - to place our results in context. References: Chen et al. 2006, ApJS, 166, 351 Li et al. 2012, ApJ, 759, 81 Lisse et al. 2009, ApJ, 701, 2019 Olofsson et al. 2012, A&A, 542, A90

  3. Granular Dilatancy and its Effect on Debris-flow Dynamics

    Science.gov (United States)

    Iverson, R. M.; George, D. L.

    2012-12-01

    Landslides and debris flows commonly exhibit the effects of variable granular dilatancy, but incorporation of these effects in predictive models of debris-flow dynamics has been lacking. We have developed a depth-averaged model of debris-flow initiation and motion that includes the effects of variable dilatancy without stipulating its influence on rheology. Instead, the apparent rheology of Coulomb-frictional debris evolves during coupled evolution of the grain concentration m, basal pore-fluid pressure, flow thickness, and flow velocity. The dilatancy angle ψ plays an intermediary role in this evolution and obeys the simple relationship tan ψ = m-meq, where meq is the grain concentration in equilibrium with the ambient stress state and flow rate. Results of recent stress-controlled rheometric experiments by Boyer et al. (DOI: 10.1103/PhysRevLett.107.188301) provide our basis for estimating meq. Relaxation of m toward meq, coupled with evolution of pore pressure, allows our model to simulate a smooth transition from static limiting equilibrium of slopes to disequilibrium flow dynamics. Use of variable friction coefficients or dam-break initial conditions is unnecessary. We have evaluated predictions of our model in three ways: (1) by examining physical implications of exact solutions of simplified model equations, (2) by comparing numerical solutions with results of controlled experiments at the USGS debris-flow flume, and (3) by comparing numerical predictions with the behavior of a large (~50 million m3) debris flow that occurred at Mt. Meager, British Columbia, in 2010. Model predictions depend mostly on initial conditions, flow-path topography, and the value of a single dimensionless parameter that represents the ratio of two key timescales. One timescale governs downslope, gravity-driven motion of debris, and the other governs pore-pressure diffusion. Values of these timescales are readily calculated from source-area geometry and standard geotechnical

  4. Catastrophe on the Horizon: A Scenario-Based Future Effect of Orbital Space Debris

    Science.gov (United States)

    2010-04-01

    space debris. The challenges are that launching of satellites and the subsequent abandonment at end-of- life has been a major contributor to the growth...introduction of extraterrestrial matter that could adversely affect the environment of the earth. 63 Another treaty that is related to orbital space debris...ISS creating a massive hole in the huge structure. The collision is so severe that it knocks out the on-board communication and life support system

  5. Estimates of marine debris accumulation on beaches are strongly affected by the temporal scale of sampling.

    Science.gov (United States)

    Smith, Stephen D A; Markic, Ana

    2013-01-01

    Marine debris is a global issue with impacts on marine organisms, ecological processes, aesthetics and economies. Consequently, there is increasing interest in quantifying the scale of the problem. Accumulation rates of debris on beaches have been advocated as a useful proxy for at-sea debris loads. However, here we show that past studies may have vastly underestimated the quantity of available debris because sampling was too infrequent. Our study of debris on a small beach in eastern Australia indicates that estimated daily accumulation rates decrease rapidly with increasing intervals between surveys, and the quantity of available debris is underestimated by 50% after only 3 days and by an order of magnitude after 1 month. As few past studies report sampling frequencies of less than a month, estimates of the scale of the marine debris problem need to be critically re-examined and scaled-up accordingly. These results reinforce similar, recent work advocating daily sampling as a standard approach for accurate quantification of available debris in coastal habitats. We outline an alternative approach whereby site-specific accumulation models are generated to correct bias when daily sampling is impractical.

  6. Protecting Spacecraft Fragments from Exposure to Small Debris

    Directory of Open Access Journals (Sweden)

    V. V. Zelentsov

    2015-01-01

    less than 4 ... 5 km/s, at higher speeds particles breaks through them. As a result, a cloud is formed. It consists of fragments, destroying particle, and debris split-off from the obstacle. For reliable protection the sandwich panels are used. Shield design comprises two panels: the first panel being multi-layer and the second one being single-layer. The task of the first panel is to provide the maximum fragmented particle and reduce its speed. The second panel protects the structure from the cloud fragments resulting from breakdown of the first panel. The European module "Columbus” that is part of the ISS and transport vehicle ATV have the protective shield of the similar construction. The shield consists of "aluminum sheet with 2 mm thickness; filler - Kevlar + Nextel + epoxy resin, thermal insulation; the second panel comprises aluminum sheet of 3 mm thickness.Modeling and experiments show high efficiency of steel mesh as a protective shield. Spacecraft design consists, mainly, of aluminum alloys therefore space debris is from the same material. At collision with steel mesh a particle is decelerated and destroyed. Therefore, timeRushan ability of the particle significantly decreases. The second layer, opposing to the impact of high-speed particles, is foam metal (foam-Lumina. It is successfully used in the automotive engineering. Ballistic fabric (such as Kevlar is capable to protect from the effect of the fragmentation cloud.

  7. Technical know-how for modeling of geological environment. (1) Overview and groundwater flow modeling

    International Nuclear Information System (INIS)

    Saegusa, Hiromitsu; Takeuchi, Shinji; Maekawa, Keisuke; Osawa, Hideaki; Semba, Takeshi

    2011-01-01

    It is important for site characterization projects to manage the decision-making process with transparency and traceability and to transfer the technical know-how accumulated during the research and development to the implementing phase and to future generations. The modeling for a geological environment is to be used to synthesize investigation results. Evaluation of the impact of uncertainties in the model is important to identify and prioritize key issues for further investigations. Therefore, a plan for site characterization should be made based on the results of the modeling. The aim of this study is to support for the planning of initial surface-based site characterization based on the technical know-how accumulated from the Mizunami Underground Research Laboratory Project and the Horonobe Underground Research Laboratory Project. These projects are broad scientific studies of the deep geological environment that are a basis for research and development for the geological disposal of high-level radioactive wastes. In this study, the work-flow of the groundwater flow modeling, which is one of the geological environment models, and is to be used for setting the area for the geological environment modeling and for groundwater flow characterization, and the related decision-making process using literature data have been summarized. (author)

  8. Modeling shoot-tip temperature in the greenhouse environment

    International Nuclear Information System (INIS)

    Faust, J.E.; Heins, R.D.

    1998-01-01

    An energy-balance model is described that predicts vinca (Catharanthus roseus L.) shoot-tip temperature using four environmental measurements: solar radiation and dry bulb, wet bulb, and glazing material temperature. The time and magnitude of the differences between shoot-tip and air temperature were determined in greenhouses maintained at air temperatures of 15, 20, 25, 30, or 35 °C. At night, shoot-tip temperature was always below air temperature. Shoot-tip temperature decreased from 0.5 to 5 °C below air temperature as greenhouse glass temperature decreased from 2 to 15 °C below air temperature. During the photoperiod under low vapor-pressure deficit (VPD) and low air temperature, shoot-tip temperature increased ≈4 °C as solar radiation increased from 0 to 600 W·m -2 . Under high VPD and high air temperature, shoot-tip temperature initially decreased 1 to 2 °C at sunrise, then increased later in the morning as solar radiation increased. The model predicted shoot-tip temperatures within ±1 °C of 81% of the observed 1-hour average shoot-tip temperatures. The model was used to simulate shoot-tip temperatures under different VPD, solar radiation, and air temperatures. Since the rate of leaf and flower development are influenced by the temperature of the meristematic tissues, a model of shoot-tip temperature will be a valuable tool to predict plant development in greenhouses and to control the greenhouse environment based on a plant temperature setpoint. (author)

  9. Coalescing Debris-Fill Complexes in Headwater Valleys of the Oregon Coast Range

    Science.gov (United States)

    Lancaster, S. T.; Grant, G. E.

    2005-12-01

    Headwater streams are important links in the sediment transport chain connecting production from steep uplands to supply in downstream, fish-bearing channels. In headwater basins that are forested and where debris flows are common, debris-flow deposition forms valley-spanning dams of wood, boulders, or both, and significant volumes of sediment are stored behind these dams. In three headwater streams (basin areas of approximately 2 sq. km) in the Oregon Coast Range, the following data were collected: (a) longitudinal channel profiles; (b) locations and heights of debris dams; (c) sediment storage volumes; and (d) exposed bank stratigraphy. In all three basins, these data indicate a zone of concentrated mainstem debris-flow deposition where stream gradients first decrease to approximately 10%. Deposits in this zone do not form fans per se but, rather, comprise coalescing debris-fill complexes. These complexes have large unit storage volumes (defined as valley-floor sediment storage volume per upstream contributing area), and because coalescing debris-fill complexes are formed in headwater valleys with relatively low bankfull discharge, these complexes represent a buffer between episodic sediment input from the hillslopes and continual sediment output to fish-bearing streams. An empirical model of susceptibility to debris-flow inundation is based on hypothesized landslide susceptibility, an observed relationship between debris-flow runout length and elevation change between source and deposit, and tributary junction angles and corroborates the occurrence of coalescing debris-fill complexes where greater debris-flow susceptibility arises and is attributable to multiple sources, e.g., tributaries and main stem. Field data and simulation modeling indicate that debris-flow deposition in these complexes is sensitive to wood volume and depositional history: Entraining wood from valley floors and spreading over prior deposits decrease debris-flow velocities and favor

  10. Evaluating tsunami hazards from debris flows

    Science.gov (United States)

    Watts, P.; Walder, J.S.; ,

    2003-01-01

    Debris flows that enter water bodies may have significant kinetic energy, some of which is transferred to water motion or waves that can impact shorelines and structures. The associated hazards depend on the location of the affected area relative to the point at which the