Sample records for solid debris bed

  1. Debris-bed friction of hard-bedded glaciers

    USGS Publications Warehouse

    Cohen, D.; Iverson, N.R.; Hooyer, T.S.; Fischer, U.H.; Jackson, M.; Moore, P.L.

    2005-01-01

    [1] Field measurements of debris-bed friction on a smooth rock tablet at the bed of Engabreen, a hard-bedded, temperate glacier in northern Norway, indicated that basal ice containing 10% debris by volume exerted local shear traction of up to 500 kPa. The corresponding bulk friction coefficient between the dirty basal ice and the tablet was between 0.05 and 0.08. A model of friction in which nonrotating spherical rock particles are held in frictional contact with the bed by bed-normal ice flow can account for these measurements if the power law exponent for ice flowing past large clasts is 1. A small exponent (n < 2) is likely because stresses in ice are small and flow is transient. Numerical calculations of the bed-normal drag force on a sphere in contact with a flat bed using n = 1 show that this force can reach values several hundred times that on a sphere isolated from the bed, thus drastically increasing frictional resistance. Various estimates of basal friction are obtained from this model. For example, the shear traction at the bed of a glacier sliding at 20 m a-1 with a geothermally induced melt rate of 0.006 m a-1 and an effective pressure of 300 kPa can exceed 100 kPa. Debris-bed friction can therefore be a major component of sliding resistance, contradicting the common assumption that debris-bed friction is negligible. Copyright 2005 by the American Geophysical Union.

  2. Entrainment of bed sediment by debris flows: results from large-scale experiments

    USGS Publications Warehouse

    Reid, Mark E.; Iverson, Richard M.; Logan, Matthew; LaHusen, Richard G.; Godt, Jonathan W.; Griswold, Julie P.

    2011-01-01

    When debris flows grow by entraining sediment, they can become especially hazardous owing to increased volume, speed, and runout. To investigate the entrainment process, we conducted eight largescale experiments in the USGS debris-flow flume. In each experiment, we released a 6 m3 water-saturated debris flow across a 47-m long, ~12-cm thick bed of partially saturated sediment lining the 31º flume. Prior to release, we used low-intensity overhead sprinkling and real-time monitoring to control the bed-sediment wetness. As each debris flow descended the flume, we measured the evolution of flow thickness, basal total normal stress, basal pore-fluid pressure, and sediment scour depth. When debris flows traveled over relatively dry sediment, net scour was minimal, but when debris flows traveled over wetter sediment (volumetric water content > 0.22), debris-flow volume grew rapidly and flow speed and runout were enhanced. Data from scour sensors showed that entrainment occurred by rapid (5-10 cm/s), progressive scour rather than by mass failure at depth. Overriding debris flows rapidly generated high basal pore-fluid pressures when they loaded and deformed bed sediment, and in wetter beds these pressures approached lithostatic levels. Reduction of intergranular friction within the bed sediment thereby enhanced scour efficiency, entrainment, and runout.

  3. Positive feedback and momentum growth during debris-flow entrainment of wet bed sediment

    USGS Publications Warehouse

    Iverson, R.M.; Reid, M.E.; Logan, M.; LaHusen, R.G.; Godt, J.W.; Griswold, J.P.

    2011-01-01

    Debris flows typically occur when intense rainfall or snowmelt triggers landslides or extensive erosion on steep, debris-mantled slopes. The flows can then grow dramatically in size and speed as they entrain material from their beds and banks, but the mechanism of this growth is unclear. Indeed, momentum conservation implies that entrainment of static material should retard the motion of the flows if friction remains unchanged. Here we use data from large-scale experiments to assess the entrainment of bed material by debris flows. We find that entrainment is accompanied by increased flow momentum and speed only if large positive pore pressures develop in wet bed sediments as the sediments are overridden by debris flows. The increased pore pressure facilitates progressive scour of the bed, reduces basal friction and instigates positive feedback that causes flow speed, mass and momentum to increase. If dryer bed sediment is entrained, however, the feedback becomes negative and flow momentum declines. We infer that analogous feedbacks could operate in other types of gravity-driven mass flow that interact with erodible beds. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  4. Coarse-grained debris flow dynamics on erodible beds

    NASA Astrophysics Data System (ADS)

    Lanzoni, Stefano; Gregoretti, Carlo; Stancanelli, Laura Maria

    2017-03-01

    A systematic set of flume experiments is used to investigate the features of velocity profiles within the body of coarse-grained debris flows and the dependence of the transport sediment concentration on the relevant parameters (runoff discharge, bed slope, grain size, and form). The flows are generated in a 10 m long laboratory flume, initially filled with a layer consisting of loose debris. After saturation, a prescribed water discharge is suddenly supplied over the granular bed, and the runoff triggers a debris flow wave that reaches nearly steady conditions. Three types of material have been used in the tests: gravel with mean grain size of 3 and 5 mm, and 3 mm glass spheres. Measured parameters included: triggering water discharge, volumetric sediment discharge, sediment concentration, flow depth, and velocity profiles. The dynamic similarity with full-sized debris flows is discussed on the basis of the relevant dimensionless parameters. Concentration data highlight the dependence on the slope angle and the importance of the quasi-static friction angle. The effects of flow rheology on the shape of velocity profiles are analyzed with attention to the role of different stress-generating mechanisms. A remarkable collapse of the dimensionless profiles is obtained by scaling the debris flow velocity with the runoff velocity, and a power law characterization is proposed following a heuristic approach. The shape of the profiles suggests a smooth transition between the different rheological regimes (collisional and frictional) that establish in the upper and lower regions of the flow and is compatible with the presence of multiple length scales dictated by the type of contacts (instantaneous or long lasting) between grains.

  5. Elementary theory of bed-sediment entrainment by debris flows and avalanches

    USGS Publications Warehouse

    Iverson, Richard M.

    2012-01-01

    Analyses of mass and momentum exchange between a debris flow or avalanche and an underlying sediment layer aid interpretations and predictions of bed-sediment entrainment rates. A preliminary analysis assesses the behavior of a Coulomb slide block that entrains bed material as it descends a uniform slope. The analysis demonstrates that the block's momentum can grow unstably, even in the presence of limited entrainment efficiency. A more-detailed, depth-integrated continuum analysis of interacting, deformable bodies identifies mechanical controls on entrainment efficiency, and shows that entrainment rates satisfy a jump condition that involves shear-traction and velocity discontinuities at the flow-bed boundary. Explicit predictions of the entrainment rateEresult from making reasonable assumptions about flow velocity profiles and boundary shear tractions. For Coulomb-friction tractions, predicted entrainment rates are sensitive to pore fluid pressures that develop in bed sediment as it is overridden. In the simplest scenario the bed sediment liquefies completely, and the entrainment-rate equation reduces toE = 2μ1gh1 cos θ(1 − λ1)/ , where θ is the slope angle, μ1 is the flow's Coulomb friction coefficient, h1 is its thickness, λ1 is its degree of liquefaction, and is its depth-averaged velocity. For values ofλ1ranging from 0.5 to 0.8, this equation predicts entrainment rates consistent with rates of 0.05 to 0.1 m/s measured in large-scale debris-flow experiments in which wet sediment beds liquefied almost completely. The propensity for bed liquefaction depends on several factors, including sediment porosity, permeability, and thickness, and rates of compression and shear deformation that occur when beds are overridden.

  6. Enhanced stability of steep channel beds to mass failure and debris flow initiation

    NASA Astrophysics Data System (ADS)

    Prancevic, J.; Lamb, M. P.; Ayoub, F.; Venditti, J. G.

    2015-12-01

    Debris flows dominate bedrock erosion and sediment transport in very steep mountain channels, and are often initiated from failure of channel-bed alluvium during storms. While several theoretical models exist to predict mass failures, few have been tested because observations of in-channel bed failures are extremely limited. To fill this gap in our understanding, we performed laboratory flume experiments to identify the conditions necessary to initiate bed failures in non-cohesive sediment of different sizes (D = 0.7 mm to 15 mm) on steep channel-bed slopes (S = 0.45 to 0.93) and in the presence of water flow. In beds composed of sand, failures occurred under sub-saturated conditions on steep bed slopes (S > 0.5) and under super-saturated conditions at lower slopes. In beds of gravel, however, failures occurred only under super-saturated conditions at all tested slopes, even those approaching the dry angle of repose. Consistent with theoretical models, mass failures under super-saturated conditions initiated along a failure plane approximately one grain-diameter below the bed surface, whereas the failure plane was located near the base of the bed under sub-saturated conditions. However, all experimental beds were more stable than predicted by 1-D infinite-slope stability models. In partially saturated sand, enhanced stability appears to result from suction stress. Enhanced stability in gravel may result from turbulent energy losses in pores or increased granular friction for failures that are shallow with respect to grain size. These grain-size dependent effects are not currently included in stability models for non-cohesive sediment, and they may help to explain better the timing and location of debris flow occurrence.

  7. Hydraulic modeling of unsteady debris-flow surges with solid-fluid interactions

    USGS Publications Warehouse

    Iverson, Richard M.

    1997-01-01

    Interactions of solid and fluid constituents produce the unique style of motion that typifies debris flows. To simulate this motion, a new hydraulic model represents debris flows as deforming masses of granular solids variably liquefied by viscous pore fluid. The momentum equation of the model describes how internal and boundary forces change as coarse-grained surge heads dominated by grain-contact friction grade into muddy debris-flow bodies more strongly influenced by fluid viscosity and pressure. Scaling analysis reveals that pore-pressure variations can cause flow resistance in surge heads to surpass that in debris-flow bodies by orders of magnitude. Numerical solutions of the coupled momentum and continuity equations provide good predictions of unsteady, nonuniform motion of experimental debris flows from initiation through deposition.

  8. Solids feed nozzle for fluidized bed

    DOEpatents

    Zielinski, Edward A.

    1982-01-01

    The vertical fuel pipe of a fluidized bed extends up through the perforated support structure of the bed to discharge granulated solid fuel into the expanded bed. A cap, as a deflecting structure, is supported above the discharge of the fuel pipe and is shaped and arranged to divert the carrier fluid and granulated fuel into the combusting bed. The diverter structure is spaced above the end of the fuel pipe and provided with a configuration on its underside to form a venturi section which generates a low pressure in the stream into which the granules of solid fuel are drawn to lengthen their residence time in the combustion zone of the bed adjacent the fuel pipe.

  9. First Stage Solid Propellant Multiply Debris Thermal Analysis

    NASA Technical Reports Server (NTRS)

    Toleman, Benjamin M.

    2011-01-01

    Destruction of a solid rocket stage of a launch vehicle can create a thermal radiation hazard for an aborting crew module. This hazard was assessed for the Constellation Program (Cx) crew and launch vehicle concept. For this concept, if an abort was initiated in first stage flight, the Crew Module (CM) will separate and be pulled away from the malfunctioning launch vehicle via a Launch Abort System (LAS). Having aborted the mission, the launch vehicle will likely be destroyed via a Flight Termination System (FTS) in order to prevent it from errantly traversing back over land and posing a risk to the public. The resulting launch vehicle debris field, composed primarily of first stage solid propellant, poses a threat to the CM. The harsh radiative thermal environment, caused by surrounding burning propellant debris, may lead to CM parachute failure. A methodology, detailed herein, has been developed to address this concern and to quantify the risk of first stage propellant debris leading to the thermal demise of the CM parachutes. Utilizing basic thermal radiation principles, a software program was developed to calculate parachute temperature as a function of time for a given abort trajectory and debris piece trajectory set. Two test cases, considered worst case aborts with regard to launch vehicle debris environments, were analyzed using the simulation: an abort declared at Mach 1 and an abort declared at maximum dynamic pressure (Max Q). For both cases, the resulting temperature profiles indicated that thermal limits for the parachutes were not exceeded. However, short duration close encounters by single debris pieces did have a significant effect on parachute temperature. Therefore while these two test cases did not indicate exceedance of thermal limits, in order to quantify the risk of parachute failure due to radiative effects from the abort environment, a more thorough probability-based analysis using the methodology demonstrated herein must be performed.

  10. Idealized debris flow in flume with bed driven by a conveyor belt

    USGS Publications Warehouse

    Ling, Chi-Hai; Chen, Cheng-lung

    1989-01-01

    The generalized viscoplastic fluid (GVF) model is used to derive the theoretical expressions of two-dimensional velocities and surface profile for debris flow established in a flume with bed driven by a conveyor belt. The rheological parameters of the GVF model are evaluated through the comparison of theoretical results with measured data. A slip velocity of the established (steady) nonuniform flow on the moving bed (i.e., the conveyor belt) is observed, and a relation between the slip velocity and the velocity gradient at the bed is derived. Two belts, one rough and the other smooth, were tested. The flow profile in the flume is found to be linear and dependent on the roughness of the belt, but not much on its speed.

  11. First Stage Solid Propellant Multi Debris Thermal Analysis

    NASA Technical Reports Server (NTRS)

    Toleman, Benjamin M.

    2011-01-01

    The crew launch vehicle considered for the Constellation (Cx) Program utilizes a first stage solid rocket motor. If an abort is initiated in first stage flight the Crew Module (CM) will separate and be pulled away from the launch vehicle via a Launch Abort System (LAS) in order to safely and quickly carry the crew away from the malfunction launch vehicle. Having aborted the mission, the launch vehicle will likely be destroyed via a Flight Termination System (FTS) in order to prevent it from errantly traversing back over land and posing a risk to the public. The resulting launch vehicle debris field, composed primarily of first stage solid propellant, poses a threat to the CM. The harsh radiative thermal environment induced by surrounding burning propellant debris may lead to CM parachute failure. A methodology, detailed herein, has been developed to address this concern and quantify the risk of first stage propellant debris leading to radiative thermal demise of the CM parachutes. Utilizing basic thermal radiation principles, a software program was developed to calculate parachute temperature as a function of time for a given abort trajectory and debris piece trajectory set. Two test cases, considered worst-case aborts with regard to launch vehicle debris environments, were analyzed using the simulation: an abort declared at Mach 1 and an abort declared at maximum dynamic pressure (Max Q). For both cases, the resulting temperature profiles indicated that thermal limits for the parachutes were not exceeded. However, short duration close encounters by single debris pieces did have a significant effect on parachute temperature, with magnitudes on the order of 10 s of degrees Fahrenheit. Therefore while these two test cases did not indicate exceedance of thermal limits, in order to quantify the risk of parachute failure due to radiative effects from the abort environment, a more thorough probability-based analysis using the methodology demonstrated herein must be

  12. Moving bed reactor setup to study complex gas-solid reactions.

    PubMed

    Gupta, Puneet; Velazquez-Vargas, Luis G; Valentine, Charles; Fan, Liang-Shih

    2007-08-01

    A moving bed scale reactor setup for studying complex gas-solid reactions has been designed in order to obtain kinetic data for scale-up purpose. In this bench scale reactor setup, gas and solid reactants can be contacted in a cocurrent and countercurrent manner at high temperatures. Gas and solid sampling can be performed through the reactor bed with their composition profiles determined at steady state. The reactor setup can be used to evaluate and corroborate model parameters accounting for intrinsic reaction rates in both simple and complex gas-solid reaction systems. The moving bed design allows experimentation over a variety of gas and solid compositions in a single experiment unlike differential bed reactors where the gas composition is usually fixed. The data obtained from the reactor can also be used for direct scale-up of designs for moving bed reactors.

  13. Experimental investigation of bubbling in particle beds with high solid holdup

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cheng, Songbai; Hirahara, Daisuke; Tanaka, Youhei

    2011-02-15

    A series of experiments on bubbling behavior in particle beds was performed to clarify three-phase flow dynamics in debris beds formed after core-disruptive accident (CDA) in sodium-cooled fast breeder reactors (FBRs). Although in the past, several experiments have been performed in packed beds to investigate flow patterns, most of these were under comparatively higher gas flow rate, which may be not expected during an early sodium boiling period in debris beds. The current experiments were conducted under two dimensional (2D) and three dimensional (3D) conditions separately, in which water was used as liquid phase, and bubbles were generated by injectingmore » nitrogen gas from the bottom of the viewing tank. Various particle-bed parameters were varied, including particle-bed height (from 30 mm to 200 mm), particle diameter (from 0.4 mm to 6 mm) and particle type (beads made of acrylic, glass, alumina and zirconia). Under these experimental conditions, three kinds of bubbling behavior were observed for the first time using digital image analysis methods that were further verified by quantitative detailed analysis of bubbling properties including surface bubbling frequency and surface bubble size under both 2D and 3D conditions. This investigation, which hopefully provides fundamental data for a better understanding and an improved estimation of CDAs in FBRs, is expected to benefit future analysis and verification of computer models developed in advanced fast reactor safety analysis codes. (author)« less

  14. Aerosol-Assisted Solid Debris Collection for the National Ignition Facility

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nelson, S L; Shaughnessy, D A; Moody, K J

    2010-05-21

    The National Ignition Facility (NIF) has been completed and has made its first shots on-target. While upcoming experiments will be focused on achieving ignition, a variety of subsequent experiments are planned for the facility, including measurement of cross sections, astrophysical measurements, and investigation of hydrodynamic instability in the target capsule. In order to successfully execute several of these planned experiments, the ability to collect solid debris following a NIF capsule shot will be required. The ability to collect and analyze solid debris generated in a shot at the National Ignition Facility (NIF) will greatly expand the number of nuclear reactionsmore » studied for diagnostic purposes. Currently, reactions are limited to only those producing noble gases for cryogenic collection and counting with the Radchem Apparatus for Gas Sampling (RAGS). The radchem solid collection diagnostic has already been identified by NIF to be valuable for the determination and understanding of mix generated in the target capsule's ablation. LLNL is currently developing this solid debris collection capability at NIF, and is in the stage of testing credible designs. Some of these designs explore the use of x-ray generated aerosols to assist in collection of solid debris. However, the variety of harsh experimental conditions this solid collection device will encounter in NIF are challenging to replicate. Experiments performed by Gary Grim et al. at Sandia National Laboratory's RHEPP1 facility have shown that ablation causes a cloud of material removed from an exposed surface to move normal to and away from the surface. This ablation is certain to be a concern in the NIF target chamber from the prompt x-rays, gamma rays, etc. generated in the shot. The cloud of ablated material could interfere with the collection of the desired reaction debris by slowing down the debris so that the kinetic energy is too low to allow implantation, or by stopping the debris from

  15. Model of Fluidized Bed Containing Reacting Solids and Gases

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Lathouwers, Danny

    2003-01-01

    A mathematical model has been developed for describing the thermofluid dynamics of a dense, chemically reacting mixture of solid particles and gases. As used here, "dense" signifies having a large volume fraction of particles, as for example in a bubbling fluidized bed. The model is intended especially for application to fluidized beds that contain mixtures of carrier gases, biomass undergoing pyrolysis, and sand. So far, the design of fluidized beds and other gas/solid industrial processing equipment has been based on empirical correlations derived from laboratory- and pilot-scale units. The present mathematical model is a product of continuing efforts to develop a computational capability for optimizing the designs of fluidized beds and related equipment on the basis of first principles. Such a capability could eliminate the need for expensive, time-consuming predesign testing.

  16. Time-series analysis on bed morphology affected by debris flows along a headwater steep channel in Ohya-kuzure landslide, central Japan

    NASA Astrophysics Data System (ADS)

    Hayakawa, Y. S.; Imaizumi, F.; Hotta, N.; Tsunetaka, H.

    2013-12-01

    Deformation of steep terrain has been occurring since the formation of Ohyakuzure landslide in 1707. Although erosion controls in recent decades have resulted in vegetation recovery in downstream portions of the landslide terrain, hillslope erosion and debris flows frequently occur in uppermost steep subwatersheds in the landslide area to yield vast amount of sediment downstream. Ichino-sawa subwatershed in the landslide terrain, where detailed monitoring of debris flows and related topographic changes have previously been performed, has particularly steep slopes, and geomorphic processes therein have been quite active. Freeze-thaw weathering of fractured bedrock on hillslopes made of shale and sandstone frequently occurs in winter to spring season, and resultant sediment particles are provided into channel beds, which act as a source of debris flows that frequently occurs in summer season with heavy or accumulated rainfalls. High-resolution assessment of erosion/deposition patterns in channel bed of the Ichinosawa catchment was performed using multi-temporal terrestrial laser scanning data covering 3 seasons for 2 years. Seasonal changes in spatial distribution of erosion and deposition in the channel bed is quantified using a 0.1-m DEM converted from the original point cloud by TLS. The multi-temporal datasets provides an estimate of annual sediment storage and yield on the order of 1,000 - 5,000 m3. Analysis of changes in elevation by transverse and longitudinal profiles shows contrasting patterns of erosion and deposition along the studied reach: in particular, changes in bed elevation is found to be less in a 50-m long reach, whose downstream part seems bounded by valley narrowing and a knickpoint. Several topographic metrics, including stream gradient, surface roughness and topographic openness, were examined to estimate the characteristics of differing transport processes induced by debris flows along the reaches.

  17. Management and characteristics of recycled manure solids used for bedding in Midwest freestall dairy herds.

    PubMed

    Husfeldt, A W; Endres, M I; Salfer, J A; Janni, K A

    2012-04-01

    Interest in using recycled manure solids (RMS) as a bedding material for dairy cows has grown in the US Midwest. Cost of common bedding materials has increased in recent years and availability has decreased. Information regarding the composition of RMS and its use as a bedding material for dairy cows in the Midwest is very limited. The objectives of this study were to characterize RMS as a bedding material, observe bedding management practices, document methods of obtaining RMS, and describe housing facilities. We visited 38 Midwest dairy operations bedding freestalls with RMS to collect data. Methods of obtaining RMS for bedding included separation of anaerobic digested manure, separation of raw manure, and separation of raw manure followed by mechanical drum-composting for 18 to 24 h. Average bedding moisture of unused RMS was 72.4% with a pH of 9.16. Unused samples contained (on a dry basis) 1.4% N, 44.9% C, 32.7C:N ratio, 0.44% P, 0.70% K, 76.5% neutral detergent fiber, 9.4% ash, 4.4% nonfiber carbohydrates, and 1.1% fat. Moisture was lowest for drum-composted solids before and after use as freestall bedding. After use in the stalls, digested solids had lower neutral detergent fiber content (70.5%) than drum-composted (75.0%) and separated raw (73.1%) solids. Total N content was greater in digested solids (2.0%) than in separated raw (1.7%) solids. Total bacterial populations in unused bedding were greatest in separated raw manure solids but were similar between digested and drum-composted manure solids. Drum-composted manure solids had no coliform bacteria before use as freestall bedding. After use as bedding, digested manure solids had lower total bacteria counts compared with drum-composted and separated raw manure solids, which had similar counts. Used bedding samples of digested solids contained fewer environmental streptococci than drum-composted and separated raw solids and had reduced Bacillus counts compared with separated raw solids. Coliform counts

  18. Apparatus for controlling molten core debris

    DOEpatents

    Golden, Martin P. [Trafford, PA; Tilbrook, Roger W. [Monroeville, PA; Heylmun, Neal F. [Pittsburgh, PA

    1977-07-19

    Apparatus for containing, cooling, diluting, dispersing and maintaining subcritical the molten core debris assumed to melt through the bottom of a nuclear reactor pressure vessel in the unlikely event of a core meltdown. The apparatus is basically a sacrificial bed system which includes an inverted conical funnel, a core debris receptacle including a spherical dome, a spherically layered bed of primarily magnesia bricks, a cooling system of zig-zag piping in graphite blocks about and below the bed and a cylindrical liner surrounding the graphite blocks including a steel shell surrounded by firebrick. Tantalum absorber rods are used in the receptacle and bed.

  19. Fixed bed pyrolysis of biomass solid waste for bio-oil

    NASA Astrophysics Data System (ADS)

    Islam, Mohammad Nurul; Ali, Mohamed Hairol Md; Haziq, Miftah

    2017-08-01

    Biomass solid waste in the form of rice husk particle is pyrolyzed in a fixed bed stainless steel pyrolysis reactor of 50 mm diameter and 50 cm length. The biomass solid feedstock is prepared prior to pyrolysis. The reactor bed is heated by means of a cylindrical heater of biomass source. A temperature of 500°C is maintained with an apperent vapor residence time of 3-5 sec. The products obtained are liquid bio-oil, solid char and gases. The liquid product yield is found to be 30% by weight of solid biomass feedstock while the solid product yield is found to be 35% by weight of solid biomass feedtock, the rest is gas. The bio-oil is a single-phase brownish color liquid of acrid smell. The heating value of the oil is determined to be 25 MJ/kg. The density and pH value are found to be 1.125 kg/m3 and 3.78 respectively.

  20. Space Shuttle Solid Rocket Booster Debris Assessment

    NASA Technical Reports Server (NTRS)

    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.

  1. Apparatus for controlling molten core debris. [LMFBR

    DOEpatents

    Golden, M.P.; Tilbrook, R.W.; Heylmun, N.F.

    1977-07-19

    Disclosed is an apparatus for containing, cooling, diluting, dispersing and maintaining subcritical the molten core debris assumed to melt through the bottom of a nuclear reactor pressure vessel in the unlikely event of a core meltdown. The apparatus is basically a sacrificial bed system which includes an inverted conical funnel, a core debris receptacle including a spherical dome, a spherically layered bed of primarily magnesia bricks, a cooling system of zig-zag piping in graphite blocks about and below the bed and a cylindrical liner surrounding the graphite blocks including a steel shell surrounded by firebrick. Tantalum absorber rods are used in the receptacle and bed. 9 claims, 22 figures.

  2. Characterization of solid fuels at pressurized fluidized bed gasification conditions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zevenhoven, R.; Hupa, M.

    1998-07-01

    The gasification of co-gasification of solid fuel (coal, peat, wood) in air-blown fluidized bed gasifiers is receiving continued attention as an alternative to entrained flow gasifiers which in general are oxygen-blown. Fluidized bed gasification of wood and wood-waste at elevated pressures, and the so-called air-blown gasification cycle are examples of processes which are under development in Europe. based on complete or partial gasification of a solid fuel in a pressurized fluidized bed. At the same time, fuel characterization data for the combination of temperature, pressure and fuel particle heating rate that is encountered in fluidized bed gasification are very scarce.more » In this paper, quantitative data on the characterization of fuels for advanced combustion and gasification technologies based on fluidized beds are given, as a result from the authors participation in the JOULE 2 extension project on clean coal technology of the European community. Eleven solid fuels, ranging from coal via peat to wood, have been studied under typical fluidized bed gasification conditions: 800--1,000 C, 1--25 bar, fuel heating rate in the order of 100--1,000 C/s. Carbon dioxide was used as gasifying agent. A pressurized thermogravimetric reactor was used for the experiments. The results show that the solid residue yield after pyrolysis/devolatilization increases with pressure and decreases with temperature. For coal, the gasification reactivity of the char increases by a factor of 3 to 4 when pressurizing from 1 to 25 bar, for the younger fuels such as peat and wood, this effect is negligible. Several empirical engineering equations are given which relate the fuel performance to the process parameters and the proximate and chemical analyses of the fuel. A pressure maximum was found at which a maximum gasification reactivity occurs, for practically all fuels, and depending on temperature. It is shown that this can be explained and modeled using a Langmuir

  3. Characterisation of solid fuels at pressurised fluidised bed gasification conditions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zebenhoven, R.; Hupa, M.

    1998-04-01

    The gasification or co-gasification of solid fuels (coal, peat, wood) in air-blown fluidised bed gasifiers is receiving continued attention as an alternative to entrained flow gasifiers which in general are oxygen-blown. Fluidised bed gasification of wood and wood-waste at elevated pressures, and the so-called air-blown gasification cycle are examples of processes which are under development in Europe, based on complete or partial gasification of a solid fuel in a pressurised fluidised bed. At the same time, fuel characterisation data for the combination of temperature, pressure and fuel particle heating rate that is encountered in fluidised bed gasification are very scarce.more » Quantitative data on the characterisation of fuels for advanced combustion and gasification technologies based on fluidised beds are given, as a result from our participation to the JOULE 2 extension project on clean coal technology of the European Community. Eleven solid fuels, ranging from coal via peat to wood, have been studied under typical fluidised bed gasification conditions: 800-1000{degrees}C, 1-25 bar, fuel heating rate in the order of 100-1000{degrees}C/s. Carbon dioxide was used as gasifying agent. A pressurised thermogravimetric reactor was used for the experiments. The results show that the solid residue yield after pyrolysis/devolatilisation. increases with pressure and decreases with temperature. For coal, the gasification reactivity of the char increases by a factor of 3 to 4 when pressurising from 1 to 25 bar, for the `younger` fuels such as peat and wood, this effect is negligible. Several empirical, `engineering` equations are given which relate the fuel performance to the process parameters and the proximate and chemical analyses of the fuel. A pressure maximum was found at which a maximum gasification reactivity occurs, for practically all fuels, and depending on temperature. It is shown that this can be explained and modelled using a Langmuir-Hinshelwood model.« less

  4. Erosion of steepland valleys by debris flows

    USGS Publications Warehouse

    Stock, J.D.; Dietrich, W.E.

    2006-01-01

    Episodic debris flows scour the rock beds of many steepland valleys. Along recent debris-flow runout paths in the western United States, we have observed evidence for bedrock lowering, primarily by the impact of large particles entrained in debris flows. This evidence may persist to the point at which debris-flow deposition occurs, commonly at slopes of less than ???0.03-0.10. We find that debris-flow-scoured valleys have a topographic signature that is fundamentally different from that predicted by bedrock river-incision models. Much of this difference results from the fact that local valley slope shows a tendency to decrease abruptly downstream of tributaries that contribute throughgoing debris flows. The degree of weathering of valley floor bedrock may also decrease abruptly downstream of such junctions. On the basis of these observations, we hypothesize that valley slope is adjusted to the long-term frequency of debris flows, and that valleys scoured by debris flows should not be modeled using conventional bedrock river-incision laws. We use field observations to justify one possible debris-flow incision model, whose lowering rate is proportional to the integral of solid inertial normal stresses from particle impacts along the flow and the number of upvalley debris-flow sources. The model predicts that increases in incision rate caused by increases in flow event frequency and length (as flows gain material) downvalley are balanced by rate reductions from reduced inertial normal stress at lower slopes, and stronger, less weathered bedrock. These adjustments lead to a spatially uniform lowering rate. Although the proposed expression leads to equilibrium long-profiles with the correct topographic signature, the crudeness with which the debris-flow dynamics are parameterized reveals that we are far from a validated debris-flow incision law. However, the vast extent of steepland valley networks above slopes of ???0.03-0.10 illustrates the need to understand debris

  5. Fluidized bed gasification of industrial solid recovered fuels.

    PubMed

    Arena, Umberto; Di Gregorio, Fabrizio

    2016-04-01

    The study evaluates the technical feasibility of the fluidized bed gasification of three solid recovered fuels (SRFs), obtained as co-products of a recycling process. The SRFs were pelletized and fed to a pilot scale bubbling fluidized bed reactor, operated in gasification and co-gasification mode. The tests were carried out under conditions of thermal and chemical steady state, with a bed of olivine particles and at different values of equivalence ratio. The results provide a complete syngas characterization, in terms of its heating value and composition (including tars, particulates, and acid/basic pollutants) and of the chemical and physical characterization of bed material and entrained fines collected at the cyclone outlet. The feasibility of the fluidized bed gasification process of the different SRFs was evaluated with the support of a material and substance flow analysis, and a feedstock energy analysis. The results confirm the flexibility of fluidized bed reactor, which makes it one of the preferable technologies for the gasification of different kind of wastes, even in co-gasification mode. The fluidized bed gasification process of the tested SRFs appears technically feasible, yielding a syngas of valuable quality for energy applications in an appropriate plant configuration. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. The Influence of Solid Rocket Motor Retro-Burns on the Space Debris Environment

    NASA Astrophysics Data System (ADS)

    Stabroth, S.; Homeister, M.; Oswald, M.; Wiedemann, C.; Klinkrad, H.; Vörsmann, P.

    The ESA space debris population model MASTER Meteoroid and Space Debris Terrestrial Environment Reference considers firings of solid rocket motors SRM as a debris source with the associated generation of slag and dust particles The resulting slag and dust population is a major contribution to the sub-millimetre size debris environment in Earth orbit The current model version MASTER-2005 is based on the simulation of 1 076 orbital SRM firings which contributed to the long-term debris environment A comparison of the modelled flux with impact data from returned surfaces shows that the shape and quantity of the modelled SRM dust distribution matches that of recent Hubble Space Telescope HST solar array measurements very well However the absolute flux level for dust is under-predicted for some of the analysed Long Duration Exposure Facility LDEF surfaces This points into the direction of some past SRM firings not included in the current event database The most suitable candidates for these firings are the large number of SRM retro-burns of return capsules Objects released by those firings have highly eccentric orbits with perigees in the lower regions of the atmosphere Thus they produce no long-term effect on the debris environment However a large number of those firings during the on-orbit time frame of LDEF might lead to an increase of the dust population for some of the LDEF surfaces In this paper the influence of SRM retro-burns on the short- and long-term debris environment is analysed The existing firing database is updated with gathered

  7. Safety apparatus for nuclear reactor to prevent structural damage from overheating by core debris

    DOEpatents

    Gabor, John D.; Cassulo, John C.; Pedersen, Dean R.; Baker, Jr., Louis

    1986-01-01

    The invention teaches safety apparatus that can be included in a nuclear reactor, either when newly fabricated or as a retrofit add-on, that will minimize proliferation of structural damage to the reactor in the event the reactor is experiencing an overheating malfunction whereby radioactive nuclear debris might break away from and be discharged from the reactor core. The invention provides a porous bed or sublayer on the lower surface of the reactor containment vessel so that the debris falls on and piles up on the bed. Vapor release elements upstand from the bed in some laterally spaced array. Thus should the high heat flux of the debris interior vaporize the coolant at that location, the vaporized coolant can be vented downwardly to and laterally through the bed to the vapor release elements and in turn via the release elements upwardly through the debris. This minimizes the pressure buildup in the debris and allows for continuing infiltration of the liquid coolant into the debris interior.

  8. Safety apparatus for nuclear reactor to prevent structural damage from overheating by core debris

    DOEpatents

    Gabor, John D.; Cassulo, John C.; Pedersen, Dean R.; Baker Jr., Louis

    1986-07-01

    The invention teaches safety apparatus that can be included in a nuclear reactor, either when newly fabricated or as a retrofit add-on, that will minimize proliferation of structural damage to the reactor in the event the reactor is experiencing an overheating malfunction whereby radioactive nuclear debris might break away from and be discharged from the reactor core. The invention provides a porous bed or sublayer on the lower surface of the reactor containment vessel so that the debris falls on and piles up on the bed. Vapor release elements upstand from the bed in some laterally spaced array. Thus should the high heat flux of the debris interior vaporize the coolant at that location, the vaporized coolant can be vented downwardly to and laterally through the bed to the vapor release elements and in turn via the release elements upwardly through the debris. This minimizes the pressure buildup in the debris and allows for continuing infiltration of the liquid coolant into the debris interior.

  9. Safety apparatus for nuclear reactor to prevent structural damage from overheating by core debris

    DOEpatents

    Gabor, J.D.; Cassulo, J.C.; Pedersen, D.R.; Baker, L. Jr.

    The invention teaches safety apparatus that can be included in a nuclear reactor, either when newly fabricated or as a retrofit add-on, that will minimize proliferation of structural damage to the reactor in the event the reactor is experiencing an overheating malfunction whereby radioactive nuclear debris might break away from and can be discharged from the reactor core. The invention provides a porous bed of sublayer on the lower surface of the reactor containment vessel so that the debris falls on and piles up on the bed. Vapor release elements upstand from the bed in some laterally spaced array. Thus should the high heat flux of the debris interior vaporize the coolant at that location, the vaporized coolant can be vented downwardly to and laterally through the bed to the vapor release elements and in turn via the release elements upwardly through the debris. This minimizes the pressure buildup in the debris and allows for continuing infiltration of the liquid coolant into the debris interior.

  10. Short communication: Environmental mastitis pathogen counts in freestalls bedded with composted and fresh recycled manure solids.

    PubMed

    Cole, K J; Hogan, J S

    2016-02-01

    An experiment was conducted to compare bacterial counts of environmental mastitis pathogens in composted recycled manure solids bedding with those in fresh recycled manure solids. Eighteen Holstein cows were housed in 1 pen with 18 stalls. One row of 9 freestalls included mattresses and was bedded weekly with composted recycled manure solids. The second row of 9 freestalls included mattresses and was bedded weekly with fresh recycled manure solids. The back one-third of stalls toward the alleyway was covered in 25 to 50 mm of bedding. Samples were taken from the back one-third of 4 stalls for both treatments on d 0, 1, 2, and 6 of each week. After 3 wk, bedding treatments were switched between rows, making the total duration 6 wk. Mean total gram-negative bacterial counts were approximately 0.5 log10 cfu/g of dry matter lower in the composted recycled manure solids on d 0 compared with fresh recycled manure solids. Klebsiella species, coliform, and Streptococcus species counts were at least 1.0 log10 cfu/g of dry matter lower in composted compared with fresh recycled manure solids on d 0. Only gram-negative bacterial counts on d 1 were reduced in composted recycled manure solids compared with fresh recycled manure solids. Differences were not observed between treatments in gram-negative bacterial, coliform, Klebsiella species, or Streptococcus species counts on d 2 and 6. Ash content was higher in composted recycled manure solids compared with fresh recycled manure solids on d 0, 1, 2, and 6. Despite the increase in ash after composting, bacterial counts of mastitis pathogens in composted recycled manure solids were comparable with those in fresh recycled manure when used as freestall bedding. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  11. Lateral solids dispersion coefficient in large-scale fluidized beds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Daoyin; Chen, Xiaoping

    2010-11-15

    The design of fuel feed ports in a large-scale fluidized bed combustor depends on the fuel characteristics and lateral solids mixing. However, the reported values of the effective lateral solids dispersion coefficient (D{sub sr}) are scattered in the broad range of 0.0001-0.1 m{sup 2}/s. With the aim of predicting D{sub sr} in wider fluidized beds which is difficult to measure directly or deduce from experimental results in lab-scale facilities, a computational method is proposed. It combines the Eulerian-Granular simulation and fictitious particle tracing technique. The value of D{sub sr} is calculated based on the movement of the tracers. The effectmore » on D{sub sr} of bed width (W) ranging from 0.4 m up to 12.8 m at different levels of superficial gas velocity (U{sub 0}) is investigated. It is found that increasing W whilst maintaining U{sub 0}, D{sub sr} initially increases markedly, then its increase rate declines, and finally it stays around a constant value. The computed values of D{sub sr} are examined quantitatively and compared with a thorough list of the measured D{sub sr} in the literature since 1980s. Agreed with the measurements performed in the pilot-scale fluidized beds, the value of D{sub sr} in wider facilities at higher fluidizing velocities is predicted to be around the order of magnitude of 0.1 m{sup 2}/s, much higher than that in lab-scale beds. Finally, the effect of D{sub sr} on the distribution of fuel particles over the cross section in fluidized beds with the specified layout of feed ports is discussed. (author)« less

  12. Numerical investigation of solid mixing in a fluidized bed coating process

    NASA Astrophysics Data System (ADS)

    Kenche, Venkatakrishna; Feng, Yuqing; Ying, Danyang; Solnordal, Chris; Lim, Seng; Witt, Peter J.

    2013-06-01

    Fluidized beds are widely used in many process industries including the food and pharmaceutical sectors. Despite being an intensive research area, there are no design rules or correlations that can be used to quantitatively predict the solid mixing in a specific system for a given set of operating conditions. This paper presents a numerical study of the gas and solid dynamics in a laboratory scale fluidized bed coating process used for food and pharmaceutical industries. An Eulerian-Eulerian model (EEM) with kinetic theory of granular flow is selected as the modeling technique, with the commercial computational fluid dynamics (CFD) software package ANSYS/Fluent being the numerical platform. The flow structure is investigated in terms of the spatial distribution of gas and solid flow. The solid mixing has been evaluated under different operating conditions. It was found that the solid mixing rate in the horizontal direction is similar to that in the vertical direction under the current design and operating conditions. It takes about 5 s to achieve good mixing.

  13. The influence of solid rocket motor retro-burns on the space debris environment

    NASA Astrophysics Data System (ADS)

    Stabroth, Sebastian; Homeister, Maren; Oswald, Michael; Wiedemann, Carsten; Klinkrad, Heiner; Vörsmann, Peter

    The ESA space debris population model MASTER (Meteoroid and Space Debris Terrestrial Environment Reference) considers firings of solid rocket motors (SRM) as a debris source with the associated generation of slag and dust particles. The resulting slag and dust population is a major contribution to the sub-millimetre size debris environment in Earth orbit. The current model version, MASTER-2005, is based on the simulation of 1076 orbital SRM firings which contributed to the long-term debris environment. A comparison of the modelled flux with impact data from returned surfaces shows that the shape and quantity of the modelled SRM dust distribution matches that of recent Hubble Space Telescope (HST) solar array measurements very well. However, the absolute flux level for dust is under-predicted for some of the analysed Long Duration Exposure Facility (LDEF) surfaces. This points into the direction of some past SRM firings not included in the current event database. The most suitable candidates for these firings are the large number of SRM retro-burns of return capsules. Objects released by those firings have highly eccentric orbits with perigees in the lower regions of the atmosphere. Thus, they produce no long-term effect on the debris environment. However, a large number of those firings during the on-orbit time frame of LDEF might lead to an increase of the dust population for some of the LDEF surfaces. In this paper, the influence of SRM retro-burns on the short- and long-term debris environment is analysed. The existing firing database is updated with gathered information of some 800 Russian retro-firings. Each firing is simulated with the MASTER population generation module. The resulting population is compared against the existing background population of SRM slag and dust particles in terms of spatial density and flux predictions.

  14. Variables controlling the recovery of ignitable liquid residues from simulated fire debris samples using solid-phase microextraction/gas chromatography

    NASA Astrophysics Data System (ADS)

    Furton, Kenneth G.; Almirall, Jose R.; Wang, Jing

    1999-02-01

    In this paper, we present data comparing a variety of different conditions for extracting ignitable liquid residues from simulated fire debris samples in order to optimize the conditions for using Solid Phase Microextraction. A simulated accelerant mixture containing 30 components, including those from light petroleum distillates, medium petroleum distillates and heavy petroleum distillates were used to study the important variables controlling Solid Phase Microextraction (SPME) recoveries. SPME is an inexpensive, rapid and sensitive method for the analysis of volatile residues from the headspace over solid debris samples in a container or directly from aqueous samples followed by GC. The relative effects of controllable variables, including fiber chemistry, adsorption and desorption temperature, extraction time, and desorption time, have been optimized. The addition of water and ethanol to simulated debris samples in a can was shown to increase the sensitivity when using headspace SPME extraction. The relative enhancement of sensitivity has been compared as a function of the hydrocarbon chain length, sample temperature, time, and added ethanol concentrations. The technique has also been optimized to the extraction of accelerants directly from water added to the fire debris samples. The optimum adsorption time for the low molecular weight components was found to be approximately 25 minutes. The high molecular weight components were found at a higher concentration the longer the fiber was exposed to the headspace (up to 1 hr). The higher molecular weight components were also found in higher concentrations in the headspace when water and/or ethanol was added to the debris.

  15. The debris-flow rheology myth

    USGS Publications Warehouse

    Iverson, R.M.; ,

    2003-01-01

    Models that employ a fixed rheology cannot yield accurate interpretations or predictions of debris-flow motion, because the evolving behavior of debris flows is too complex to be represented by any rheological equation that uniquely relates stress and strain rate. Field observations and experimental data indicate that debris behavior can vary from nearly rigid to highly fluid as a consequence of temporal and spatial variations in pore-fluid pressure and mixture agitation. Moreover, behavior can vary if debris composition changes as a result of grain-size segregation and gain or loss of solid and fluid constituents in transit. An alternative to fixed-rheology models is provided by a Coulomb mixture theory model, which can represent variable interactions of solid and fluid constituents in heterogeneous debris-flow surges with high-friction, coarse-grained heads and low-friction, liquefied tails. ?? 2003 Millpress.

  16. Fluidized bed combustion of high-volatile solid fuels: An assessment of char attrition and volatile matter segregation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chirone, R.; Marzocchella, A.; Salatino, P.

    1999-07-01

    A simple lumped-parameter model of a bubbling fluidized bed combustor fueled with high-volatile solid fuels is presented. The combustor is divided into three sections: the dense bed, the splashing region and the freeboard. Material balances on fixed carbon, volatile matter and oxygen are set up, taking into account fuel particle fragmentation and attrition, volatile matter segregation as well as postcombustion of both carbon fines and volatiles escaping the bed. A basic assumption of the model is that the combustion pathway that foes from the raw fuel to the combustion products proceeds via the formation of three phases: volatile matter, relativelymore » large non-elutriable char particles and fine char particles of elutriable size. The study is complemented by a simplified thermal balance on the splashing zone taking into account volatiles and elutriated fines postcombustion and radiative and convective heat fluxes to the bed and the freeboard. Results from calculations with either low- or high-volatile solid fuels indicate that low-volatile bituminous coal combustion takes place essentially in the bed mostly via coarse char particles combustion, while high-volatile biomass fuel combustion occurs to comparable extents both in the bed and in the splashing region of the combustor. Depending on the extent of volatile matter segregation with respect to the bed, a significant fraction of the heat is released into the splashing region of the combustor and this results into an increase of temperature in this region. Extensive bed solids recirculation associated to bubble bursting/solids ejection at the bed surface together with effective gas-solids heat transfer promotes thermal feedback from this region to the bed of as much as 90% of the heat release by volatile matter and elutriated fines afterburning.« less

  17. Controlling thermal properties of dense gas fluidized beds for concentrated solar power by internal and external solids circulation

    NASA Astrophysics Data System (ADS)

    Ammendola, Paola; Bareschino, Piero; Chirone, Riccardo; Salatino, Piero; Solimene, Roberto

    2017-06-01

    Fluidization technology displays a long record of success stories, mostly related to applications to thermal and thermochemical processes, which are fostering extension to novel and relatively unexplored fields. Application of fluidized beds to collection and thermal storage of solar radiation in Concentrated Solar Power (CSP) is one of the most promising, a field which poses challenging issues and great opportunities to fluidization scientists and technologists. The potential of this growing field calls for reconsideration of some of the typical design and operation guidelines and criteria, with the goal of exploiting the inherently good thermal performances of gas-fluidized beds at their best. "Creative" and non-conventional design and operation of fluidized beds, like those based on internal and external solids circulation, may be beneficial to the enhancement of thermal diffusivity and surface-to-bed heat transfer, improving the potential for application in the very demanding context of CSP with thermal energy storage. This paper investigated: i) a fluidized bed configuration with an uneven distribution of the fluidizing gas to promote vortices in the scale of bed height (internal solids circulation); ii) a dual fluidized bed configuration characterized by an external solids circulation achieved by the operation of a riser and a bubbling fluidized bed. CFD simulations showed the hydrodynamics conditions under which the internal solids circulation was established. The hydrodynamic characterization of the external solids circulation was achieved by an experimental study carried out with different cold models. The dual fluidized bed system was optimized in terms of operating conditions and geometrical features of the connections between two fluidized beds.

  18. Manufacturing Solid Dosage Forms from Bulk Liquids Using the Fluid-bed Drying Technology.

    PubMed

    Qi, Jianping; Lu, Y I; Wu, Wei

    2015-01-01

    Solid dosage forms are better than liquid dosage forms in many ways, such as improved physical and chemical stability, ease of storage and transportation, improved handling properties, and patient compliance. Therefore, it is required to transform dosage forms of liquid origins into solid dosage forms. The functional approaches are to absorb the liquids by solid excipients or through drying. The conventional drying technologies for this purpose include drying by heating, vacuum-, freeze- and spray-drying, etc. Among these drying technologies, fluidbed drying emerges as a new technology that possesses unique advantages. Fluid-bed drying or coating is highly efficient in solvent removal, can be performed at relatively low temperatures, and is a one-step process to manufacture formulations in pellet forms. In this article, the status of the art of manufacturing solid dosage forms from bulk liquids by fluid-bed drying technology was reviewed emphasizing on its application in solid dispersion, inclusion complexes, self-microemulsifying systems, and various nanoscale drug delivery systems.

  19. Pyrethroid sorption to Sacramento River suspended solids and bed sediments

    PubMed Central

    Fojut, Tessa L.; Young, Thomas M.

    2011-01-01

    Sorption of pyrethroid insecticides to solid materials will typically dominate the fate and transport of these hydrophobic compounds in aquatic environments. Batch reactor isotherm experiments were performed with bifenthrin and λ-cyhalothrin with suspended material and bed sediment collected from the Sacramento River, CA. These batch reactor experiments were performed with low spiking concentrations and a long equilibration time (28 d) to be more relevant to environmental conditions. Sorption to suspended material and bed sediment was compared to examine the role of differential sorption between these phases in the environmental transport of pyrethroids. The equilibrium sorption data were fit to the Freundlich isotherm model and fit with r2 > 0.87 for all experiments. Freundlich exponents ranged from 0.72 ± 0.19 to 1.07 ± 0.050, indicating sorption nonlinearity for some of the experimental conditions and linearity for others over the concentration range tested. The Freundlich capacity factors were larger for the suspended solids than for the bed sediments and the suspended material had a higher specific surface area and higher organic carbon content compared to the bed sediment. Calculated organic carbon-normalized distribution coefficients were larger than those previously reported in the literature by approximately an order of magnitude and ranged from 106.16 to 106.68 at an equilibrium aqueous concentration of 0.1 µg/L. Higher than expected sorption of pyrethroids to the tested materials may be explained by sorption to black carbon and/or mineral surfaces. PMID:21191877

  20. Cooling of core debris and the impact on containment pressure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, J.W.

    1981-07-01

    An evaluation of the core debris/water interactions associated with a postulated meltdown of a PWR and its impact on the containment pressure is presented. In the event of a complete core meltdown in a PWR, the interaction of molten debris with water in the bottom head of the reactor vessel could result in complete evaporation of water and breach of the vessel wall. In the reactor cavity, the debris-water interaction may lead to a rapid generation of steam, which could lead to pressures beyond the containment building limit. Previous analysis of the debris-water interactions with the MARCH code was basedmore » on the single-sphere model, in which the internal and surface heat transfer are the controlling mechanisms. In this study, the potential in-vessel and ex-vessel debris-water interactions are analyzed in terms of porous debris bed models. The debris cooling and steam generation are controlled by the hydrodynamics of the two-phase flow. The porous models developed by Dhir-Catton and by Lipinski were examined and used to test their impact on containment dynamics. The tests include several particle sizes from 1 mm to 50 mm. Detailed transient data on the pressure, temperature, and mass of steam in the containment building was obtained for all cases. Bands of pressure variation which represents the possible pressure rise under accident conditions were obtained for the Dhir-Catton model and for the Lipinski model. The results show that, for the case of a wet cavity, the magnitude of the predicted pressure rises is not strongly affected by the different models. The occurrence of the peak pressure, however, is considerably delayed by using the debris bed model. For the case of a dry cavity, a large reduction of the peak pressure is obtained by using the debris bed model.« less

  1. Non-local rheology of stony debris flow propagating over a cohesionless sediment bed

    NASA Astrophysics Data System (ADS)

    Lanzoni, Stefano; Gregoretti, Carlo

    2016-04-01

    normal to the flow, with particular attention to the role played by frictional stresses near to the movable bed over which the debris flow propagates.

  2. The physics of debris flows

    NASA Astrophysics Data System (ADS)

    Iverson, Richard M.

    1997-08-01

    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

  3. The physics of debris flows

    USGS Publications Warehouse

    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

  4. Evaluation of a headspace solid-phase microextraction method for the analysis of ignitable liquids in fire debris.

    PubMed

    Fettig, Ina; Krüger, Simone; Deubel, Jan H; Werrel, Martin; Raspe, Tina; Piechotta, Christian

    2014-05-01

    The chemical analysis of fire debris represents a crucial part in fire investigations to determine the cause of a fire. A headspace solid-phase microextraction (HS-SPME) procedure for the detection of ignitable liquids in fire debris using a fiber coated with a mixture of three different sorbent materials (Divinylbenzene/Carboxen/Polydimethylsiloxane, DVB/CAR/PDMS) is described. Gasoline and diesel fuel were spiked upon a preburnt matrix (wood charcoal), extracted and concentrated with HS-SPME and then analyzed with gas chromatography/mass spectrometry (GC/MS). The experimental conditions--extraction temperature, incubation and exposure time--were optimized. To assess the applicability of the method, fire debris samples were prepared in the smoke density chamber (SDC) and a controlled-atmosphere cone calorimeter. The developed methods were successfully applied to burnt particleboard and carpet samples. The results demonstrate that the procedure that has been developed here is suitable for detecting these ignitable liquids in highly burnt debris. © 2013 American Academy of Forensic Sciences.

  5. Phase shift method to estimate solids circulation rate in circulating fluidized beds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ludlow, James Christopher; Panday, Rupen; Shadle, Lawrence J.

    2013-01-01

    While solids circulation rate is a critical design and control parameter in circulating fluidized bed (CFB) reactor systems, there are no available techniques to measure it directly at conditions of industrial interest. Cold flow tests have been conducted at NETL in an industrial scale CFB unit where the solids flow has been the topic of research in order to develop an independent method which could be applied to CFBs operating under the erosive and corrosive high temperatures and pressures of a coal fired boiler or gasifier. The dynamic responses of the CFB loop to modest modulated aeration flows in themore » return leg or standpipe were imposed to establish a periodic response in the unit without causing upset in the process performance. The resulting periodic behavior could then be analyzed with a dynamic model and the average solids circulation rate could be established. This method was applied to the CFB unit operated under a wide range of operating conditions including fast fluidization, core annular flow, dilute and dense transport, and dense suspension upflow. In addition, the system was operated in both low and high total solids inventories to explore the influence of inventory limiting cases on the estimated results. The technique was able to estimate the solids circulation rate for all transport circulating fluidized beds when operating above upper transport velocity, U{sub tr2}. For CFB operating in the fast fluidized bed regime (i.e., U{sub g}< U{sub tr2}), the phase shift technique was not successful. The riser pressure drop becomes independent of the solids circulation rate and the mass flow rate out of the riser does not show modulated behavior even when the riser pressure drop does.« less

  6. Pyrethroid sorption to Sacramento River suspended solids and bed sediments.

    PubMed

    Fojut, Tessa L; Young, Thomas M

    2011-04-01

    Sorption of pyrethroid insecticides to solid materials will typically dominate the fate and transport of these hydrophobic compounds in aquatic environments. Batch reactor isotherm experiments were performed with bifenthrin and λ-cyhalothrin with suspended material and bed sediment collected from the Sacramento River, California, USA. These batch reactor experiments were performed with low spiking concentrations and a long equilibration time (28 d) to be more relevant to environmental conditions. Sorption to suspended material and bed sediment was compared to examine the role of differential sorption between these phases in the environmental transport of pyrethroids. The equilibrium sorption data were fit to the Freundlich isotherm model and fit with r(2)  > 0.87 for all experiments. Freundlich exponents ranged from 0.72 ± 0.19 to 1.07 ± 0.050, indicating sorption nonlinearity for some of the experimental conditions and linearity for others over the concentration range tested. The Freundlich capacity factors were larger for the suspended solids than for the bed sediments, and the suspended material had a higher specific surface area and higher organic carbon content compared to the bed sediment. Calculated organic carbon-normalized distribution coefficients were larger than those previously reported in the literature, by approximately an order of magnitude, and ranged from 10(6.16) to 10(6.68) at an equilibrium aqueous concentration of 0.1 µg/L. Higher than expected sorption of pyrethroids to the tested materials may be explained by sorption to black carbon and/or mineral surfaces. Copyright © 2011 SETAC.

  7. Hybrid fluidized bed combuster

    DOEpatents

    Kantesaria, Prabhudas P.; Matthews, Francis T.

    1982-01-01

    A first atmospheric bubbling fluidized bed furnace is combined with a second turbulent, circulating fluidized bed furnace to produce heat efficiently from crushed solid fuel. The bed of the second furnace receives the smaller sizes of crushed solid fuel, unreacted limestone from the first bed, and elutriated solids extracted from the flu gases of the first bed. The two-stage combustion of crushed solid fuel provides a system with an efficiency greater than available with use of a single furnace of a fluidized bed.

  8. On the Superficial Gas Velocity in Deep Gas-Solid Fluidized Beds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Tingwen; Grace, John; Shadle, Lawrence

    2011-11-15

    The superficial gas velocity is one of the key parameters used to determine the flow hydrodynamics in gas–solids fluidized beds. However, the superficial velocity varies with height in practice, and there is no consistent basis for its specification. Different approaches to determine the superficial gas velocity in a deep gas–solids system are shown to cause difficulties in developing models and in comparing predictions with experimental results. In addition, the reference conditions for superficial gas velocity are important in modeling of deep gas–solids systems where there is a considerable pressure drop.

  9. A new model for two-dimensional numerical simulation of pseudo-2D gas-solids fluidized beds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Tingwen; Zhang, Yongmin

    2013-10-11

    Pseudo-two dimensional (pseudo-2D) fluidized beds, for which the thickness of the system is much smaller than the other two dimensions, is widely used to perform fundamental studies on bubble behavior, solids mixing, or clustering phenomenon in different gas-solids fluidization systems. The abundant data from such experimental systems are very useful for numerical model development and validation. However, it has been reported that two-dimensional (2D) computational fluid dynamic (CFD) simulations of pseudo-2D gas-solids fluidized beds usually predict poor quantitative agreement with the experimental data, especially for the solids velocity field. In this paper, a new model is proposed to improve themore » 2D numerical simulations of pseudo-2D gas-solids fluidized beds by properly accounting for the frictional effect of the front and back walls. Two previously reported pseudo-2D experimental systems were simulated with this model. Compared to the traditional 2D simulations, significant improvements in the numerical predictions have been observed and the predicted results are in better agreement with the available experimental data.« less

  10. Short communication: Bacterial counts in recycled manure solids bedding replaced daily or deep packed in freestalls.

    PubMed

    Sorter, D E; Kester, H J; Hogan, J S

    2014-05-01

    An experiment was conducted to compare bacterial counts of mastitis pathogens in deep-packed manure solids bedding with those in manure solids bedding replaced daily from mattresses. Eighteen Holstein cows were housed in 1 pen with 18 stalls. One row of 9 stalls was equipped with mattresses topped with bedding. The back one-third of these stalls toward the alleyway was covered in 25 mm of recycled manure solids, which was removed daily for the next 6 d and replaced with bedding from the brisket board and lunge space areas of stalls. The second row of 9 stalls was bedded for 3 wk with 100 to 150 mm of deep-pack recycled manure bedding from which only fecal matter was removed daily. After 3 wk, bedding treatments were changed between rows in a switchback design. Mean total gram-negative bacterial counts did not differ between treatments throughout the experiment. Coliform and Klebsiella spp. bacterial counts were lower in daily replaced bedding compared with deep pack across the experiment and on each of d 0, 1, 2, and 6. Streptococcal counts were reduced in daily replacement stalls compared with deep-pack stalls on d 0 and greater in daily replacement stalls compared with deep-pack stalls on d 1, 2, and 6. Daily replacement of recycled manure bedding from the back one-third of the stalls appeared to be an effective approach to reducing exposure to coliforms, specifically Klebsiella, but not streptococci. However, bacterial counts in bedding from both treatments were elevated throughout the trial and resulted in considerable risk for exposure to teats and development of intramammary infections. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  11. Debris Flows and Related Phenomena

    NASA Astrophysics Data System (ADS)

    Ancey, C.

    Torrential floods are a major natural hazard, claiming thousands of lives and millions of dollars in lost property each year in almost all mountain areas on the Earth. After a catastrophic eruption of Mount St. Helen in the USA in May 1980, water from melting snow, torrential rains from the eruption cloud, and water displaced from Spirit Lake mixed with deposited ash and debris to produce very large debris flows and cause extensive damage and loss of life [1]. During the 1985 eruption of Nevado del Ruiz in Colombia, more than 20,000 people perished when a large debris flow triggered by the rapid melting of snow and ice at the volcano summit, swept through the town of Armero [2]. In 1991, the eruption of Pinatubo volcano in the Philippines disperses more than 5 cubic kilometres of volcanic ash into surrounding valleys. Much of that sediment has subsequently been mobilised as debris flows by typhoon rains and has devastated more than 300 square kilometres of agricultural land. Even, in Eur opean countries, recent events that torrential floods may have very destructive effects (Sarno and Quindici in southern Italy in May 1998, where approximately 200 people were killed). The catastrophic character of these floods in mountainous watersheds is a consequence of significant transport of materials associated with water flows. Two limiting flow regimes can be distinguished. Bed load and suspension refer to dilute transport of sediments within water. This means that water is the main agent in the flow dynamics and that the particle concentration does not exceed a few percent. Such flows are typically two-phase flows. In contrast, debris flows are mas s movements of concentrated slurries of water, fine solids, rocks and boulders. As a first approximation, debris flows can be treated as one-phase flows and their flow properties can be studied using classical rheological methods. The study of debris flows is a very exciting albeit immature science, made up of disparate elements

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Numerical investigation of debris materials prior to debris flow hazards using satellite images

    NASA Astrophysics Data System (ADS)

    Zhang, N.; Matsushima, T.

    2018-05-01

    The volume of debris flows occurred in mountainous areas is mainly affected by the volume of debris materials deposited at the valley bottom. Quantitative evaluation of debris materials prior to debris flow hazards is important to predict and prevent hazards. At midnight on 7th August 2010, two catastrophic debris flows were triggered by the torrential rain from two valleys in the northern part of Zhouqu City, NW China, resulting in 1765 fatalities and huge economic losses. In the present study, a depth-integrated particle method is adopted to simulate the debris materials, based on 2.5 m resolution satellite images. In the simulation scheme, the materials are modeled as dry granular solids, and they travel down from the slopes and are deposited at the valley bottom. The spatial distributions of the debris materials are investigated in terms of location, volume and thickness. Simulation results show good agreement with post-disaster satellite images and field observation data. Additionally, the effect of the spatial distributions of the debris materials on subsequent debris flows is also evaluated. It is found that the spatial distributions of the debris materials strongly influence affected area, runout distance and flow discharge. This study might be useful in hazard assessments prior to debris flow hazards by investigating diverse scenarios in which the debris materials are unknown.

  14. Effect of Superficial Gas Velocity on the Solid Temperature Distribution in Gas Fluidized Beds with Heat Production

    PubMed Central

    2017-01-01

    The hydrodynamics and heat transfer of cylindrical gas–solid fluidized beds for polyolefin production was investigated with the two-fluid model (TFM) based on the kinetic theory of granular flow (KTGF). It was found that the fluidized bed becomes more isothermal with increasing superficial gas velocity. This is mainly due to the increase of solids circulation and improvement in gas solid contact. It was also found that the average Nusselt number weakly depends on the gas velocity. The TFM results were qualitatively compared with simulation results of computational fluid dynamics combined with the discrete element model (CFD-DEM). The TFM results were in very good agreement with the CFD-DEM outcomes, so the TFM can be a reliable source for further investigations of fluidized beds especially large lab-scale reactors PMID:29187774

  15. Numerical modelling of biomass combustion: Solid conversion processes in a fixed bed furnace

    NASA Astrophysics Data System (ADS)

    Karim, Md. Rezwanul; Naser, Jamal

    2017-06-01

    Increasing demand for energy and rising concerns over global warming has urged the use of renewable energy sources to carry a sustainable development of the world. Bio mass is a renewable energy which has become an important fuel to produce thermal energy or electricity. It is an eco-friendly source of energy as it reduces carbon dioxide emissions. Combustion of solid biomass is a complex phenomenon due to its large varieties and physical structures. Among various systems, fixed bed combustion is the most commonly used technique for thermal conversion of solid biomass. But inadequate knowledge on complex solid conversion processes has limited the development of such combustion system. Numerical modelling of this combustion system has some advantages over experimental analysis. Many important system parameters (e.g. temperature, density, solid fraction) can be estimated inside the entire domain under different working conditions. In this work, a complete numerical model is used for solid conversion processes of biomass combustion in a fixed bed furnace. The combustion system is divided in to solid and gas phase. This model includes several sub models to characterize the solid phase of the combustion with several variables. User defined subroutines are used to introduce solid phase variables in commercial CFD code. Gas phase of combustion is resolved using built-in module of CFD code. Heat transfer model is modified to predict the temperature of solid and gas phases with special radiation heat transfer solution for considering the high absorptivity of the medium. Considering all solid conversion processes the solid phase variables are evaluated. Results obtained are discussed with reference from an experimental burner.

  16. Effects of debris-flow composition on runout and erosion

    NASA Astrophysics Data System (ADS)

    Haas, T. D.; Kleinhans, M. G.

    2016-12-01

    Predicting debris-flow runout is of major importance for hazard mitigation. Apart from topography and volume, runout depends on debris-flow composition (i.e., particle-size distribution and water content), but how is poorly understood. Moreover, debris flows can grow greatly in size by entrainment of bed material, enhancing their volume and thereby runout and hazardous impact. Debris-flow erosion rates also depend on debris-flow composition, but the relation between the two is largely unexplored. Composition thus strongly affects the dynamics of debris flows. We experimentally investigate the effects of composition on debris-flow runout and erosion. We find a clear optimum in the relations of runout with coarse-material fraction and clay fraction. Increasing coarse material concentration leads to larger runout. However, excess coarse material results in a large accumulation of coarse debris at the flow front and enhances diffusivity, increasing frontal friction and decreasing runout. Increasing clay content initially enhances runout, but too much clay leads to very viscous flows, reducing runout. We further find that debris-flow runout depends at least as much on composition as on topography. In general, erosion depth increases with basal shear stress in our experiments, while there is no correlation with grain collisional stress. There are substantial differences in the scour caused by different types of debris flows. Mean and maximum erosion depths generally become larger with increasing water fraction and grain size and decrease with increasing clay content. However, the erodibility of the very coarse-grained experimental debris flows is unrelated to basal shear stress. This relates to the relatively large influence of grain-collisional stress to the total bed stress in these flows (30-50%). The relative effect of grain-collisional stress is low in the other experimental debris flows (<5%) causing erosion to be largely controlled by basal shear stress. These

  17. Gas-solid fluidized bed reactors: Scale-up, flow regimes identification and hydrodynamics

    NASA Astrophysics Data System (ADS)

    Zaid, Faraj Muftah

    This research studied the scale-up, flow regimes identification and hydrodynamics of fluidized beds using 6-inch and 18- inch diameter columns and different particles. One of the objectives was to advance the scale-up of gas-solid fluidized bed reactors by developing a new mechanistic methodology for hydrodynamic similarity based on matching the radial or diameter profile of gas phase holdup, since gas dynamics dictate the hydrodynamics of these reactors. This has been successfully achieved. However, the literature reported scale-up methodology based on matching selected dimensionless groups was examined and it was found that it was not easy to match the dimensionless groups and hence, there was some deviation in the hydrodynamics of the studied two different fluidized beds. A new technique based on gamma ray densitometry (GRD) was successfully developed and utilized to on-line monitor the implementation of scale-up, to identify the flow regime, and to measure the radial or diameter profiles of gas and solids holdups. CFD has been demonstrated as a valuable tool to enable the implementation of the newly developed scale-up methodology based on finding the conditions that provide similar or closer radial profile or cross sectional distribution of the gas holdup. As gas velocity increases, solids holdup in the center region of the column decreases in the fully developed region of both 6 inch and 18 inch diameter columns. Solids holdup increased with the increase in the particles size and density. Upflowing particles velocity increased with the gas velocity and became steeper at high superficial gas velocity at all axial heights where the center line velocity became higher than that in the wall region. Smaller particles size and lower density gave larger upflowing particles velocity. Minimum fluidization velocity and transition velocity from bubbly to churn turbulent flow regimes were found to be lower in 18 inch diameter column compared to those obtained in 6 inch

  18. The Transportation of Debris by Running Water

    USGS Publications Warehouse

    Gilbert, Grove Karl; Murphy, Edward Charles

    1914-01-01

    Scope.-The finer debris transported by a stream is borne in suspension. The coarser is swept along the channel bed. The suspended load is readily sampled and estimated, and much is known as to its quantity. The bed load is inaccessible and we are without definite information as to its amount. The primary purpose of the investigation was to learn the laws which control the movement of bed load, and especially to determine how the quantity of load is related to the stream's slope and discharge and to the degree of comminution of the debris. Method.-To this end a laboratory was equipped at Berkeley, Cal., and experiments were performed in which each of the three conditions mentioned was separately varied and the resulting variations of load were observed and measured. Sand and gravel were sorted by sieves into grades of uniform size. Determinate discharges were used. In each experiment a specific load was fed to a stream of specific width and discharge, and measurement was made of the slope to which the stream automatically adjusted its bed so as to enable the current to transport the load. The slope factor.-For each combination of discharge, width, and grade of debris there is a slope, called competent slope, which limits transportation. With lower slopes there is no load, or the stream has no capacity for load. With higher slopes capacity exists; and increase of slope gives increase of capacity. The value of capacity is approximately proportional to a power of the excess of slope above competent slope. If S equal the stream's slope and sigma equal competent slope, then the stream's capacity varies as (S - sigma)n. This is not a deductive, but an empiric law. The exponent n has not a fixed value, but an indefinite series of values depending on conditions. Its range of values in the experience of the laboratory is from 0.93 to 2.37, the values being greater as the discharges are smaller or the debris is coarser. The discharge factor.-For each combination of width

  19. Coupled Eulerian-Lagrangian transport of large debris by tsunamis

    NASA Astrophysics Data System (ADS)

    Conde, Daniel A. S.; Ferreira, Rui M. L.; Sousa Oliveira, Carlos

    2016-04-01

    Tsunamis are notorious for the large disruption they can cause on coastal environments, not only due to the imparted momentum of the incoming wave but also due to its capacity to transport large quantities of solid debris, either from natural or human-made sources, over great distances. A 2DH numerical model under development at CERIS-IST (Ferreira et al., 2009; Conde, 2013) - STAV2D - capable of simulating solid transport in both Eulerian and Lagrangian paradigms will be used to assess the relevance of Lagrangian-Eulerian coupling when modelling the transport of solid debris by tsunamis. The model has been previously validated and applied to tsunami scenarios (Conde, 2013), being well-suited for overland tsunami propagation and capable of handling morphodynamic changes in estuaries and seashores. The discretization scheme is an explicit Finite Volume technique employing flux-vector splitting and a reviewed Roe-Riemann solver. Source term formulations are employed in a semi-implicit way, including the two-way coupling of the Lagrangian and Eulerian solvers by means of conservative mass and momentum transfers between fluid and solid phases. The model was applied to Sines Port, a major commercial port in Portugal, where two tsunamigenic scenarios are considered: an 8.5 Mw scenario, consistent with the Great Lisbon Earthquake and Tsunami of the 1st November 1755 (Baptista, 2009), and an hypothetical 9.5 Mw worst-case scenario based on the same historical event. Open-ocean propagation of these scenarios were simulated with GeoClaw model from ClawPack (Leveque, 2011). Following previous efforts on the modelling of debris transport by tsunamis in seaports (Conde, 2015), this work discusses the sensitivity of the obtained results with respect to the phenomenological detail of the employed Eulerian-Lagrangian formulation and the resolution of the mesh used in the Eulerian solver. The results have shown that the fluid to debris mass ratio is the key parameter regarding the

  20. An Assessment of Potential Detectors to Monitor the Man-made Orbital Debris Environment. [space debris

    NASA Technical Reports Server (NTRS)

    Reynolds, R. C.; Ruck, G. T.

    1983-01-01

    Observations using NORAD radar showed that man made debris exceeds the natural environment for large objects. For short times (a few days to a few weeks) after solid rocket motor (SRM) firings in LEO, man made debris in the microparticle size range also appears to exceed the meteoroid environment. The properties of the debris population between these size regimes is currently unknown as there has been no detector system able to perform the required observations. The alternatives for obtaining data on this currently unobserved segment of the population are assessed.

  1. APPARATUS FOR SHORT TIME MEASUREMENTS IN A FIXED-BED, GAS/SOLID REACTOR

    EPA Science Inventory

    An apparatus for exposure of a solid to reactive process gas is described which makes possible short time (≥ 0.3 to 15 s) exposures in a fixed-bed reactor. Operating conditions for differential reaction with respect to the gas concentration and rapid quench for arresting hi...

  2. Sediment entrainment by debris flows: In situ measurements from the headwaters of a steep catchment

    USGS Publications Warehouse

    McCoy, S.W.; Kean, Jason W.; Coe, Jeffrey A.; Tucker, G.E.; Staley, Dennis M.; Wasklewicz, T.A.

    2012-01-01

    Debris flows can dramatically increase their volume, and hence their destructive potential, by entraining sediment. Yet quantitative constraints on rates and mechanics of sediment entrainment by debris flows are limited. Using an in situ sensor network in the headwaters of a natural catchment we measured flow and bed properties during six erosive debris-flow events. Despite similar flow properties and thicknesses of bed sediment entrained across all events, time-averaged entrainment rates were significantly faster for bed sediment that was saturated prior to flow arrival compared with rates for sediment that was dry. Bed sediment was entrained from the sediment-surface downward in a progressive fashion and occurred during passage of dense granular fronts as well as water-rich, inter-surge flow.En massefailure of bed sediment along the sediment-bedrock interface was never observed. Large-magnitude, high-frequency fluctuations in total normal basal stress were dissipated within the upper 5 cm of bed sediment. Within this near surface layer, concomitant fluctuations in Coulomb frictional resistance are expected, irrespective of the influence of pore fluid pressure or fluctuations in shear stress. If the near-surface sediment was wet as it was overridden by a flow, additional large-magnitude, high-frequency pore pressure fluctuations were measured in the near-surface bed sediment. These pore pressure fluctuations propagated to depth at subsonic rates and in a diffusive manner. The depth to which large excess pore pressures propagated was typically less than 10 cm, but scaled as (D/fi)0.5, in which D is the hydraulic diffusivity and fi is the frequency of a particular pore pressure fluctuation. Shallow penetration depths of granular-normal-stress fluctuations and excess pore pressures demonstrate that only near-surface bed sediment experiences the full dynamic range of effective-stress fluctuations, and as a result, can be more easily entrained than deeper sediment

  3. Validation of a 2.5D CFD model for cylindrical gas–solids fluidized beds

    DOE PAGES

    Li, Tingwen

    2015-09-25

    The 2.5D model recently proposed by Li et al. (Li, T., Benyahia, S., Dietiker, J., Musser, J., and Sun, X., 2015. A 2.5D computational method to simulate cylindrical fluidized beds. Chemical Engineering Science. 123, 236-246.) was validated for two cylindrical gas-solids bubbling fluidized bed systems. Different types of particles tested under various flow conditions were simulated using the traditional 2D model and the 2.5D model. Detailed comparison against the experimental measurements on solid concentration and velocity were conducted. Comparing to the traditional Cartesian 2D flow simulation, the 2.5D model yielded better agreement with the experimental data especially for the solidmore » velocity prediction in the column wall region.« less

  4. Orbital Debris and NASA's Measurement Program

    NASA Astrophysics Data System (ADS)

    Africano, J. L.; Stansbery, E. G.

    2002-05-01

    Since the launch of Sputnik in 1957, the number of manmade objects in orbit around the Earth has dramatically increased. The United States Space Surveillance Network (SSN) tracks and maintains orbits on over nine thousand objects down to a limiting diameter of about ten centimeters. Unfortunately, active spacecraft are only a small percentage ( ~ 7%) of this population. The rest of the population is orbital debris or ``space junk" consisting of expended rocket bodies, dead payloads, bits and pieces from satellite launches, and fragments from satellite breakups. The number of these smaller orbital debris objects increases rapidly with decreasing size. It is estimated that there are at least 130,000 orbital debris objects between one and ten centimeters in diameter. Most objects smaller than 10 centimeters go untracked! As the orbital debris population grows, the risk to other orbiting objects, most importantly manned space vehicles, of a collision with a piece of debris also grows. The kinetic energy of a solid 1 cm aluminum sphere traveling at an orbital velocity of 10 km/sec is equivalent to a 400 lb. safe traveling at 60 mph. Fortunately, the volume of space in which the orbiting population resides is large, collisions are infrequent, but they do occur. The Space Shuttle often returns to earth with its windshield pocked with small pits or craters caused by collisions with very small, sub-millimeter-size pieces of debris (paint flakes, particles from solid rocket exhaust, etc.), and micrometeoroids. To get a more complete picture of the orbital-debris environment, NASA has been using both radar and optical techniques to monitor the orbital debris environment. This paper gives an overview of the orbital debris environment and NASA's measurement program.

  5. Spatial patterns of streambed morphology around woody debris: flume experiments and field observations on the effects of woody debris on streambed morphology

    NASA Astrophysics Data System (ADS)

    Leung, V.; Montgomery, D. R.

    2010-12-01

    The interactions between woody debris, fluid flow and sediment transport in rivers play a fundamental role in ecogeomorphology, affecting channel roughness, streambed morphology, and sediment transport and storage. In particular, woody debris increases the hydraulic and topographic complexity in rivers, leading to a greater diversity of aquatic habitats and an increase in the number of large pools that are important fish habitat and breeding grounds. In the past decade, engineered logjams have become an increasingly used tool in river management for simultaneously decreasing the rate of riverbank migration and improving aquatic habitat. Sediment deposits around woody debris build up riverbanks and counteract bank migration caused by erosion. Previous experiments of flow visualization around model woody debris suggest the amount of sediment scour and deposition are primarily related to the presence of roots and the obstructional area of the woody debris. We present the results of field surveys and sediment transport experiments of streambed morphology around stationary woody debris on a mobile bed. These experiments test the effects of root presence, root geometry and log orientation of individual stationary trees on streambed morphology. The flume contains a deformable sediment bed of medium sand, and has subcritical and turbulent flow, corresponding to flow conditions found in nature. Field surveys on the Hoh River, WA, measure the local streambed morphology around woody debris (e.g. pool and gravel-bar length, width and depth), as well as woody debris characteristics (e.g. tree diameter, tree length, root diameter and root depth). We quantified the amount of local sediment scour and deposition around woody debris of varying sizes, geometries and orientations relative to flow. We find that: 1) the presence of roots on woody debris leads to greater areas of both sediment scour and deposition; and 2) the amount of sediment scour and deposition are related to the

  6. Debris flow monitoring in the Acquabona watershed on the Dolomites (Italian Alps)

    USGS Publications Warehouse

    Berti, M.; Genevois, R.; LaHusen, R.; Simoni, A.; Tecca, P.R.

    2000-01-01

    In 1997 a field monitoring system was installed in Acquabona Creek in the Dolomites (Eastern Italian Alps) to observe the hydrologic conditions for debris flow occurrence and some dynamic properties of debris flow. The monitoring system consists of three remote stations: an upper one located at the head of a deeply-incised channel and two others located downstream. The system is equipped with sensors for measuring rainfall, pore pressures in the mobile channel bottom, ground vibrations, debris flow depth, total normal stress and fluid pore-pressure at the base of the flow. Two video cameras record events at the upper channel station and one video is installed at the lowermost station. During summer 1998, three debris flows (volumes from less than 1000 m3 up to 9000 m3) occurred at Acquabona. The following results were obtained from a preliminary analysis of the data: 1) All of the flows were triggered by rainfalls of less than 1 hour duration, with peak rainfall intensities ranging from 4.8 to 14.7 mm / 10 minute. 2) Debris flows initiated in several reaches of the channel, including the head of the talus slope. 3) The initial surges of the mature flows had a higher solid concentration and a lower velocity (up to 4 m/s) than succeeding, more dilute surges (more than 7 m/s). 4) Total normal stress and pore fluid pressures measured at the base of the flow (mean depth about 1.1 m) were similar (about 15 kPa), indicating a completely liquefied flow. 5) Peak flows entrained debris at a rate of about 6 m3/m of channel length and channel bed scouring was proportional to the local slope gradient and was still evident in the lower channel where the slope was 7??. ?? 2000 Elsevier Science Ltd. All rights reserved.

  7. Coupled prediction of flash flood response and debris flow occurrence: Application on an alpine extreme flood event

    NASA Astrophysics Data System (ADS)

    Destro, Elisa; Amponsah, William; Nikolopoulos, Efthymios I.; Marchi, Lorenzo; Marra, Francesco; Zoccatelli, Davide; Borga, Marco

    2018-03-01

    The concurrence of flash floods and debris flows is of particular concern, because it may amplify the hazard corresponding to the individual generative processes. This paper presents a coupled modelling framework for the predictions of flash flood response and of the occurrence of debris flows initiated by channel bed mobilization. The framework combines a spatially distributed flash flood response model and a debris flow initiation model to define a threshold value for the peak flow which permits identification of channelized debris flow initiation. The threshold is defined over the channel network as a function of the upslope area and of the local channel bed slope, and it is based on assumptions concerning the properties of the channel bed material and of the morphology of the channel network. The model is validated using data from an extreme rainstorm that impacted the 140 km2 Vizze basin in the Eastern Italian Alps on August 4-5, 2012. The results show that the proposed methodology has improved skill in identifying the catchments where debris-flows are triggered, compared to the use of simpler thresholds based on rainfall properties.

  8. Qualitative numerical study of simultaneous high-G-intensified gas–solids contact, separation and segregation in a bi-disperse rotating fluidized bed in a vortex chamber

    DOE PAGES

    De Wilde, Juray; Richards, George; Benyahia, Sofiane

    2016-05-13

    Coupled discrete particle method – computational fluid dynamics simulations are carried out to demonstrate the potential of combined high-G-intensified gas-solids contact, gas-solids separation and segregation in a rotating fluidized bed in a static vortex chamber. A case study with two distinct types of particles is focused on. When feeding solids using a standard solids inlet design, a dense and uniform rotating fluidized bed is formed, guaranteeing intense gas-solids contact. The presence of both types of particles near the chimney region reduces, however, the strength of the central vortex and is detrimental for separation and segregation. Optimization of the solids inletmore » design is required, as illustrated by stopping the solids feeding. High-G separation and segregation of the batch of particles is demonstrated, as the strength of the central vortex is restored. The flexibility with respect to the gas flow rate of the bed density and uniformity and of the gas-solids separation and segregation is demonstrated, a unique feature of vortex chamber generated rotating fluidized beds. With the particles considered in this case study, turbulent dispersion by large eddies in the gas phase is shown to have only a minor impact on the height of the inner bed of small/light particles.« less

  9. Debris flows: behavior and hazard assessment

    USGS Publications Warehouse

    Iverson, Richard M.

    2014-01-01

    Debris flows are water-laden masses of soil and fragmented rock that rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form lobate deposits when they spill onto valley floors. Because they have volumetric sediment concentrations that exceed 40 percent, maximum speeds that surpass 10 m/s, and sizes that can range up to ~109 m3, debris flows can denude slopes, bury floodplains, and devastate people and property. Computational models can accurately represent the physics of debris-flow initiation, motion and deposition by simulating evolution of flow mass and momentum while accounting for interactions of debris' solid and fluid constituents. The use of physically based models for hazard forecasting can be limited by imprecise knowledge of initial and boundary conditions and material properties, however. Therefore, empirical methods continue to play an important role in debris-flow hazard assessment.

  10. A novel mechanical model for phase-separation in debris flows

    NASA Astrophysics Data System (ADS)

    Pudasaini, Shiva P.

    2015-04-01

    Understanding the physics of phase-separation between solid and fluid phases as a two-phase mass moves down slope is a long-standing challenge. Here, I propose a fundamentally new mechanism, called 'separation-flux', that leads to strong phase-separation in avalanche and debris flows. This new model extends the general two-phase debris flow model (Pudasaini, 2012) to include a separation-flux mechanism. The new flux separation mechanism is capable of describing and controlling the dynamically evolving phase-separation, segregation, and/or levee formation in a real two-phase, geometrically three-dimensional debris flow motion and deposition. These are often observed phenomena in natural debris flows and industrial processes that involve the transportation of particulate solid-fluid mixture material. The novel separation-flux model includes several dominant physical and mechanical aspects that result in strong phase-separation (segregation). These include pressure gradients, volume fractions of solid and fluid phases and their gradients, shear-rates, flow depth, material friction, viscosity, material densities, boundary structures, gravity and topographic constraints, grain shape, size, etc. Due to the inherent separation mechanism, as the mass moves down slope, more and more solid particles are brought to the front, resulting in a solid-rich and mechanically strong frontal surge head followed by a weak tail largely consisting of the viscous fluid. The primary frontal surge head followed by secondary surge is the consequence of the phase-separation. Such typical and dominant phase-separation phenomena are revealed here for the first time in real two-phase debris flow modeling and simulations. However, these phenomena may depend on the bulk material composition and the applied forces. Reference: Pudasaini, Shiva P. (2012): A general two-phase debris flow model. J. Geophys. Res., 117, F03010, doi: 10.1029/2011JF002186.

  11. Debris mapping sensor technology project summary: Technology flight experiments program area of the space platforms technology program

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The topics presented are covered in viewgraph form. Programmatic objectives are: (1) to improve characterization of the orbital debris environment; and (2) to provide a passive sensor test bed for debris collision detection systems. Technical objectives are: (1) to study LEO debris altitude, size and temperature distribution down to 1 mm particles; (2) to quantify ground based radar and optical data ambiguities; and (3) to optimize debris detection strategies.

  12. An Assessment of the Role of Solid Rocket Motors in the Generation of Orbital Debris

    NASA Technical Reports Server (NTRS)

    Mulrooney, Mark

    2004-01-01

    Through an intensive collection and assimilation effort of Solid Rocket Motor (SRM) related data and resources, the author offers a resolution to the uncertainties surrounding SRM particulate generation, sufficiently so to enable a first-order incorporation of SRMs as a source term in space debris environment definition. The following five key conclusions are derived: 1) the emission of particles in the size regime of greatest concern from an orbital debris hazard perspective (D > 100 micron), and in significant quantities, occurs only during the Tail-off phase of SRM burn activity, 2) the velocity of these emissions is correspondingly small - between 0 and 100 m/s, 3) the total Tail-off emitted mass is between approximately 0.04 and 0.65% of the initial propellant mass, 4) the majority of Tail-off emissions occur during the 30 second period that begins as the chamber pressure declines below approximately 34.5 kPa (5 psia) and 5) the size distribution for the emitted particles ranges from 100 micron

  13. Local CFD kinetic model of cadmium vaporization during fluid bed incineration of municipal solid waste.

    PubMed

    Soria, J; Gauthier, D; Falcoz, Q; Flamant, G; Mazza, G

    2013-03-15

    The emissions of heavy metals during incineration of Municipal Solid Waste (MSW) are a major issue to health and the environment. It is then necessary to well quantify these emissions in order to accomplish an adequate control and prevent the heavy metals from leaving the stacks. In this study the kinetic behavior of Cadmium during Fluidized Bed Incineration (FBI) of artificial MSW pellets, for bed temperatures ranging from 923 to 1073 K, was modeled. FLUENT 12.1.4 was used as the modeling framework for the simulations and implemented together with a complete set of user-defined functions (UDFs). The CFD model combines the combustion of a single solid waste particle with heavy metal (HM) vaporization from the burning particle, and it takes also into account both pyrolysis and volatiles' combustion. A kinetic rate law for the Cd release, derived from the CFD thermal analysis of the combusting particle, is proposed. The simulation results are compared with experimental data obtained in a lab-scale fluidized bed incinerator reported in literature, and with the predicted values from a particulate non-isothermal model, formerly developed by the authors. The comparison shows that the proposed CFD model represents very well the evolution of the HM release for the considered range of bed temperature. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Slit-check dams for the control of debris flow

    NASA Astrophysics Data System (ADS)

    Armanini, Aronne; Larcher, Michele

    2017-04-01

    Debris flows are paroxysmal events that mobilize, alongside water, huge quantities of sediment in a very short time, then with both solid and liquid huge discharges, possibly exceeding the capacity of the current torrent restoration works. In this respect, the climate change forcing cannot be ignored. In the majority of urbanized areas, that are generally the most vulnerable, there is often not enough space to create channelling works able to let the volumes pass through without overflowing. The simplest, less expensive and most sustainable solution consists in reducing the peak solid discharge by creating storage areas upstream of the settlements, typically upstream of the alluvial fans, allowing for reduced works of canalization, that are compatible with the constraints imposed by the urbanization. The general idea consists in storing a part of the flowing solids during the peak of the hydrograph and releasing it in a successive phase or during minor floods. For this purpose, and in order to optimize the solid peak discharge reduction, it is necessary that properly designed open-check dams, capable of inducing a significative sedimentation of the solid discharge only when this exceeds a design-threshold value, control the deposition basins. A correct design of the check dam is crucial in order to induce the sedimentation in the right amount and at the right moment: a too early sedimentation might fill the volume before the peak, like in the case of close-check dams, while a too weak sedimentation might not use the whole available volume. In both cases, the channelling works might not be sufficient to let all the flow pass through, compromising the safety of the settlement. To avoid this inconvenience, we propose the use of slit-check dams, whose efficiency has already been proved for bed load. Check dams are often designed only on the base of the designer's experience. Besides, even today it is often believed that the filtering effect of open check dams is

  15. Erosion and deposition on a debris-flow fan

    NASA Astrophysics Data System (ADS)

    Densmore, A. L.; Schuerch, P.; Rosser, N. J.; McArdell, B. W.

    2011-12-01

    The ability of a debris flow to entrain or deposit sediment controls the downstream evolution of flow volume, and ultimately dictates both the geomorphic impact of the flow and the potential hazard that it represents. Our understanding of the patterns of, and controls on, such flow volume changes remains extremely limited, however, partly due to a poor mechanistic grasp of the interactions between debris flows and their bed and banks. In addition, we lack a good understanding of the cumulative long-term effects of sequences of flows in a single catchment-fan system. Here we begin to address these issues by using repeated terrestrial laser scanning (TLS) to characterize the detailed surface change associated with the passage of multiple debris flows on the Illgraben fan, Switzerland. We calculate surface elevation change along a 300 m study reach, and from this derive the downfan rate of flow volume change, or lag rate; for comparison, we also derive the spatially-averaged lag rate over the entire ~2 km length of the fan. Lag rates are broadly comparable over both length scales, indicating that flow behavior does not vary significantly across the fan for most flows, but importantly we find that flow volume at the fan head is a poor predictor of volume at the fan toe. The sign and magnitude of bed elevation change scale with local flow depth; at flow depths < 2 m, erosion and deposition are approximately equally likely, but erosion becomes increasingly dominant for flow depths > 2 m. On the Illgraben fan, this depth corresponds to a basal shear stress of 3-4 kPa. Because flow depth is in part a function of channel cross-sectional topography, which varies strongly both within and between flows, this result indicates that erosion and deposition are likely to be highly dynamic. The dependence of flow volume change on both the channel topography and the flow history may thus complicate efforts to predict debris-flow inundation areas by simple flow routing. We then apply

  16. Fluid bed gasification--plasma converter process generating energy from solid waste: experimental assessment of sulphur species.

    PubMed

    Morrin, Shane; Lettieri, Paola; Chapman, Chris; Taylor, Richard

    2014-01-01

    Often perceived as a Cinderella material, there is growing appreciation for solid waste as a renewable content thermal process feed. Nonetheless, research on solid waste gasification and sulphur mechanisms in particular is lacking. This paper presents results from two related experiments on a novel two stage gasification process, at demonstration scale, using a sulphur-enriched wood pellet feed. Notable SO2 and relatively low COS levels (before gas cleaning) were interesting features of the trials, and not normally expected under reducing gasification conditions. Analysis suggests that localised oxygen rich regions within the fluid bed played a role in SO2's generation. The response of COS to sulphur in the feed was quite prompt, whereas SO2 was more delayed. It is proposed that the bed material sequestered sulphur from the feed, later aiding SO2 generation. The more reducing gas phase regions above the bed would have facilitated COS--hence its faster response. These results provide a useful insight, with further analysis on a suite of performed experiments underway, along with thermodynamic modelling. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Runoff-generated debris flows: observations and modeling of surge initiation, magnitude, and frequency

    USGS Publications Warehouse

    Kean, Jason W.; McCoy, Scott W.; Tucker, Gregory E.; Staley, Dennis M.; Coe, Jeffrey A.

    2013-01-01

    Runoff during intense rainstorms plays a major role in generating debris flows in many alpine areas and burned steeplands. Yet compared to debris flow initiation from shallow landslides, the mechanics by which runoff generates a debris flow are less understood. To better understand debris flow initiation by surface water runoff, we monitored flow stage and rainfall associated with debris flows in the headwaters of two small catchments: a bedrock-dominated alpine basin in central Colorado (0.06 km2) and a recently burned area in southern California (0.01 km2). We also obtained video footage of debris flow initiation and flow dynamics from three cameras at the Colorado site. Stage observations at both sites display distinct patterns in debris flow surge characteristics relative to rainfall intensity (I). We observe small, quasiperiodic surges at low I; large, quasiperiodic surges at intermediate I; and a single large surge followed by small-amplitude fluctuations about a more steady high flow at high I. Video observations of surge formation lead us to the hypothesis that these flow patterns are controlled by upstream variations in channel slope, in which low-gradient sections act as “sediment capacitors,” temporarily storing incoming bed load transported by water flow and periodically releasing the accumulated sediment as a debris flow surge. To explore this hypothesis, we develop a simple one-dimensional morphodynamic model of a sediment capacitor that consists of a system of coupled equations for water flow, bed load transport, slope stability, and mass flow. This model reproduces the essential patterns in surge magnitude and frequency with rainfall intensity observed at the two field sites and provides a new framework for predicting the runoff threshold for debris flow initiation in a burned or alpine setting.

  18. Depositional processes in large-scale debris-flow experiments

    USGS Publications Warehouse

    Major, J.J.

    1997-01-01

    This study examines the depositional process and characteristics of deposits of large-scale experimental debris flows (to 15 m3) composed of mixtures of gravel (to 32 mm), sand, and mud. The experiments were performed using a 95-m-long, 2-m-wide debris-flow flume that slopes 31??. Following release, experimental debris flows invariably developed numerous shallow (???10 cm deep) surges. Sediment transported by surges accumulated abruptly on a 3?? runout slope at the mouth of the flume. Deposits developed in a complex manner through a combination of shoving forward and shouldering aside previously deposited debris and through progressive vertical accretion. Progressive accretion by the experimental flows is contrary to commonly assumed en masse sedimentation by debris flows. Despite progressive sediment emplacement, deposits were composed of unstratified accumulations of generally unsorted debris; hence massively textured, poorly sorted debris-flow deposits are not emplaced uniquely en masse. The depositional process was recorded mainly by deposit morphology and surface texture and was not faithfully registered by interior sedimentary texture; homogeneous internal textures could be misinterpreted as the result of en masse emplacement by a single surge. Deposition of sediment by similar, yet separate, debris flows produced a homogenous, massively textured composite deposit having little stratigraphic distinction. Similar deposit characteristics and textures are observed in natural debris-flow deposits. Experimental production of massively textured deposits by progressive sediment accretion limits interpretations that can be drawn from deposit characteristics and casts doubt on methods of estimating flow properties from deposit thickness or from relations between particle size and bed thickness.

  19. ASTM standards for fire debris analysis: a review.

    PubMed

    Stauffer, Eric; Lentini, John J

    2003-03-12

    The American Society for Testing and Materials (ASTM) recently updated its standards E 1387 and E 1618 for the analysis of fire debris. The changes in the classification of ignitable liquids are presented in this review. Furthermore, a new standard on extraction of fire debris with solid phase microextraction (SPME) was released. Advantages and drawbacks of this technique are presented and discussed. Also, the standard on cleanup by acid stripping has not been reapproved. Fire debris analysts that use the standards should be aware of these changes.

  20. Fluid bed gasification – Plasma converter process generating energy from solid waste: Experimental assessment of sulphur species

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Morrin, Shane, E-mail: shane.morrin@ucl.ac.uk; Advanced Plasma Power, Swindon, Wiltshire SN3 4DE; Lettieri, Paola, E-mail: p.lettieri@ucl.ac.uk

    2014-01-15

    Highlights: • We investigate gaseous sulphur species whilst gasifying sulphur-enriched wood pellets. • Experiments performed using a two stage fluid bed gasifier – plasma converter process. • Notable SO{sub 2} and relatively low COS levels were identified. • Oxygen-rich regions of the bed are believed to facilitate SO{sub 2}, with a delayed release. • Gas phase reducing regions above the bed would facilitate more prompt COS generation. - Abstract: Often perceived as a Cinderella material, there is growing appreciation for solid waste as a renewable content thermal process feed. Nonetheless, research on solid waste gasification and sulphur mechanisms in particularmore » is lacking. This paper presents results from two related experiments on a novel two stage gasification process, at demonstration scale, using a sulphur-enriched wood pellet feed. Notable SO{sub 2} and relatively low COS levels (before gas cleaning) were interesting features of the trials, and not normally expected under reducing gasification conditions. Analysis suggests that localised oxygen rich regions within the fluid bed played a role in SO{sub 2}’s generation. The response of COS to sulphur in the feed was quite prompt, whereas SO{sub 2} was more delayed. It is proposed that the bed material sequestered sulphur from the feed, later aiding SO{sub 2} generation. The more reducing gas phase regions above the bed would have facilitated COS – hence its faster response. These results provide a useful insight, with further analysis on a suite of performed experiments underway, along with thermodynamic modelling.« less

  1. Debris flow initiation in proglacial gullies on Mount Rainier, Washington

    NASA Astrophysics Data System (ADS)

    Legg, Nicholas T.; Meigs, Andrew J.; Grant, Gordon E.; Kennard, Paul

    2014-12-01

    Effects of climate change, retreating glaciers, and changing storm patterns on debris flow hazards concern managers in the Cascade Range (USA) and mountainous areas worldwide. During an intense rainstorm in November 2006, seven debris flows initiated from proglacial gullies of separate basins on the flanks of Mount Rainier. Gully heads at glacier termini and widespread failure of gully walls imply that overland flow was transformed into debris flow along gullies. We characterized gully change and morphology, and assessed spatial distributions of debris flows to infer the processes and conditions for debris flow initiation. Slopes at gully heads were greater than ~ 0.35 m m- 1 (19°) and exhibited a significant negative relationship with drainage area. A break in slope-drainage area trends among debris flow gullies also occurs at ~ 0.35 m m- 1, representing a possible transition to fluvial sediment transport and erosion. An interpreted hybrid model of debris flow initiation involves bed failure near gully heads followed by sediment recruitment from gully walls along gully lengths. Estimates of sediment volume loss from gully walls demonstrate the importance of sediment inputs along gullies for increasing debris flow volumes. Basin comparisons revealed significantly steeper drainage networks and higher elevations in debris flow-producing than non-debris flow-producing proglacial areas. The high slopes and elevations of debris flow-producing proglacial areas reflect positive slope-elevation trends for the Mount Rainier volcano. Glacier extent therefore controls the slope distribution in proglacial areas, and thus potential for debris flow generation. As a result, debris flow activity may increase as glacier termini retreat onto slopes inclined at angles above debris flow initiation thresholds.

  2. Two stage fluid bed-plasma gasification process for solid waste valorisation: Technical review and preliminary thermodynamic modelling of sulphur emissions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Morrin, Shane, E-mail: shane.morrin@ucl.ac.uk; Advanced Plasma Power, South Marston Business park, Swindon, SN3 4DE; Lettieri, Paola, E-mail: p.lettieri@ucl.ac.uk

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer We investigate sulphur during MSW gasification within a fluid bed-plasma process. Black-Right-Pointing-Pointer We review the literature on the feed, sulphur and process principles therein. Black-Right-Pointing-Pointer The need for research in this area was identified. Black-Right-Pointing-Pointer We perform thermodynamic modelling of the fluid bed stage. Black-Right-Pointing-Pointer Initial findings indicate the prominence of solid phase sulphur. - Abstract: Gasification of solid waste for energy has significant potential given an abundant feed supply and strong policy drivers. Nonetheless, significant ambiguities in the knowledge base are apparent. Consequently this study investigates sulphur mechanisms within a novel two stage fluid bed-plasma gasification process.more » This paper includes a detailed review of gasification and plasma fundamentals in relation to the specific process, along with insight on MSW based feedstock properties and sulphur pollutant therein. As a first step to understanding sulphur partitioning and speciation within the process, thermodynamic modelling of the fluid bed stage has been performed. Preliminary findings, supported by plant experience, indicate the prominence of solid phase sulphur species (as opposed to H{sub 2}S) - Na and K based species in particular. Work is underway to further investigate and validate this.« less

  3. Solid fuel feed system for a fluidized bed

    DOEpatents

    Jones, Brian C.

    1982-01-01

    A fluidized bed for the combustion of coal, with limestone, is replenished with crushed coal from a system discharging the coal laterally from a station below the surface level of the bed. A compartment, or feed box, is mounted at one side of the bed and its interior separated from the bed by a weir plate beneath which the coal flows laterally into the bed while bed material is received into the compartment above the plate to maintain a predetermined minimum level of material in the compartment.

  4. Selective mixed-bed solid phase extraction of atrazine herbicide from environmental water samples using molecularly imprinted polymer.

    PubMed

    Zarejousheghani, Mashaalah; Fiedler, Petra; Möder, Monika; Borsdorf, Helko

    2014-11-01

    A novel approach for the selective extraction of organic target compounds from water samples has been developed using a mixed-bed solid phase extraction (mixed-bed SPE) technique. The molecularly imprinted polymer (MIP) particles are embedded in a network of silica gel to form a stable uniform porous bed. The capabilities of this method are demonstrated using atrazine as a model compound. In comparison to conventional molecularly imprinted-solid phase extraction (MISPE), the proposed mixed-bed MISPE method in combination with gas chromatography-mass spectrometry (GC-MS) analysis enables more reproducible and efficient extraction performance. After optimization of operational parameters (polymerization conditions, bed matrix ingredients, polymer to silica gel ratio, pH of the sample solution, breakthrough volume plus washing and elution conditions), improved LODs (1.34 µg L(-1) in comparison to 2.25 µg L(-1) obtained using MISPE) and limits of quantification (4.5 µg L(-1) for mixed-bed MISPE and 7.5 µg L(-1) for MISPE) were observed for the analysis of atrazine. Furthermore, the relative standard deviations (RSDs) for atrazine at concentrations between 5 and 200 µg L(-1) ranged between 1.8% and 6.3% compared to MISPE (3.5-12.1%). Additionally, the column-to-column reproducibility for the mixed-bed MISPE was significantly improved to 16.1%, compared with 53% that was observed for MISPE. Due to the reduced bed-mass sorbent and at optimized conditions, the total amount of organic solvents required for conditioning, washing and elution steps reduced from more than 25 mL for conventional MISPE to less than 2 mL for mixed-bed MISPE. Besides reduced organic solvent consumption, total sample preparation time of the mixed-bed MISPE method relative to the conventional MISPE was reduced from more than 20 min to less than 10 min. The amount of organic solvent required for complete elution diminished from 3 mL (conventional MISPE) to less than 0.4 mL with the mixed-bed

  5. Experimental observations of granular debris flows

    NASA Astrophysics Data System (ADS)

    Ghilardi, P.

    2003-04-01

    Various tests are run using two different laboratory flumes with rectangular cross section and transparent walls. The grains used in a single experiment have an almost constant grain sizes; mean diameter ranges from 5 mm to 20 mm. In each test various measurements are taken: hydrograms, velocity distribution near the transparent walls and on the free surface, average flow concentration. Concentration values are measured taking samples. Velocity distributions are obtained from movies recorded by high speed video cameras capable of 350 frames per second; flow rates and depth hydrograms are computed from the same velocity distributions. A gate is installed at the beginning of one of the flumes; this gate slides normally to the bed and opens very quickly, reproducing a dam-break. Several tests are run using this device, varying channel slope, sediment concentration, initial mixture thickness before the gate. Velocity distribution in the flume is almost constant from left to right, except for the flow sections near the front. The observed discharges and velocities are less than those given by a classic dam break formula, and depend on sediment concentration. The other flume is fed by a mixture with constant discharge and concentration, and is mainly used for measuring velocity distributions when the flow is uniform, with both rigid and granular bed, and to study erosion/deposition processes near debris flow dams or other mitigation devices. The equilibrium slope of the granular bed is very close to that given by the classical equilibrium formulas for debris flow. Different deposition processes are observed depending on mixture concentration and channel geometry.

  6. Systems and Sensors for Debris-flow Monitoring and Warning

    PubMed Central

    Arattano, Massimo; Marchi, Lorenzo

    2008-01-01

    Debris flows are a type of mass movement that occurs in mountain torrents. They consist of a high concentration of solid material in water that flows as a wave with a steep front. Debris flows can be considered a phenomenon intermediate between landslides and water floods. They are amongst the most hazardous natural processes in mountainous regions and may occur under different climatic conditions. Their destructiveness is due to different factors: their capability of transporting and depositing huge amounts of solid materials, which may also reach large sizes (boulders of several cubic meters are commonly transported by debris flows), their steep fronts, which may reach several meters of height and also their high velocities. The implementation of both structural and non-structural control measures is often required when debris flows endanger routes, urban areas and other infrastructures. Sensor networks for debris-flow monitoring and warning play an important role amongst non-structural measures intended to reduce debris-flow risk. In particular, debris flow warning systems can be subdivided into two main classes: advance warning and event warning systems. These two classes employ different types of sensors. Advance warning systems are based on monitoring causative hydrometeorological processes (typically rainfall) and aim to issue a warning before a possible debris flow is triggered. Event warning systems are based on detecting debris flows when these processes are in progress. They have a much smaller lead time than advance warning ones but are also less prone to false alarms. Advance warning for debris flows employs sensors and techniques typical of meteorology and hydrology, including measuring rainfall by means of rain gauges and weather radar and monitoring water discharge in headwater streams. Event warning systems use different types of sensors, encompassing ultrasonic or radar gauges, ground vibration sensors, videocameras, avalanche pendulums

  7. The study of solid circulation rate in a compartmented fluidized bed gasifier (CFBG)

    NASA Astrophysics Data System (ADS)

    Wee, S. K.; Pok, Y. W.; Law, M. C.; Lee, V. C. C.

    2016-06-01

    Biomass waste has been abundantly available in Malaysia since the booming of palm oil industry. In order to tackle this issue, gasification is seen a promising technology to convert waste into energy. In view of the heat requirement for endothermic gasification reaction as well as the complex design and operation of multiple fluidized beds, compartmented fluidized bed gasifier (CFBG) with the combustor and the gasifier as separate compartments is proposed. As such, solid circulation rate (SCR) is one of the essential parameters for steady gasification and combustion to be realized in their respective compartments. Experimental and numerical studies (CFD) on the effect of static bed height, main bed aeration, riser aeration and v-valve aeration on SCR have been conducted in a cold- flow CFBG model with only river sand as the fluidizing medium. At lower operating range, the numerical simulations under-predict the SCR as compared to that of the experimental results. Also, it predicts slightly different trends over the range. On the other hand, at higher operating range, the numerical simulations are able to capture those trends as observed in the experimental results at the lower operating range. Overall, the numerical results compare reasonably well with that of the experimental works.

  8. Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed.

    PubMed

    Sun, Rui; Ismail, Tamer M; Ren, Xiaohan; Abd El-Salam, M

    2015-05-01

    In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on the combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k-ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Debris thickness patterns on debris-covered glaciers

    NASA Astrophysics Data System (ADS)

    Anderson, Leif S.; Anderson, Robert S.

    2018-06-01

    Many debris-covered glaciers have broadly similar debris thickness patterns: surface debris thickens and tends to transition from convex- to concave-up-down glacier. We explain this pattern using theory (analytical and numerical models) paired with empirical observations. Down glacier debris thickening results from the conveyor-belt-like nature of the glacier surface in the ablation zone (debris can typically only be added but not removed) and from the inevitable decline in ice surface velocity toward the terminus. Down-glacier thickening of debris leads to the reduction of sub-debris melt and debris emergence toward the terminus. Convex-up debris thickness patterns occur near the up-glacier end of debris covers where debris emergence dominates (ablation controlled). Concave-up debris thickness patterns occur toward glacier termini where declining surface velocities dominate (velocity controlled). A convex-concave debris thickness profile inevitably results from the transition between ablation-control and velocity-control down-glacier. Debris thickness patterns deviating from this longitudinal shape are most likely caused by changes in hillslope debris supply through time. By establishing this expected debris thickness pattern, the effects of climate change on debris cover can be better identified.

  10. Method of burning sulfur-containing fuels in a fluidized bed boiler

    DOEpatents

    Jones, Brian C.

    1982-01-01

    A method of burning a sulfur-containing fuel in a fluidized bed of sulfur oxide sorbent wherein the overall utilization of sulfur oxide sorbent is increased by comminuting the bed drain solids to a smaller average particle size, preferably on the order of 50 microns, and reinjecting the comminuted bed drain solids into the bed. In comminuting the bed drain solids, particles of spent sulfur sorbent contained therein are fractured thereby exposing unreacted sorbent surface. Upon reinjecting the comminuted bed drain solids into the bed, the newly-exposed unreacted sorbent surface is available for sulfur oxide sorption, thereby increasing overall sorbent utilization.

  11. Fluidized bed combustor modeling

    NASA Technical Reports Server (NTRS)

    Horio, M.; Rengarajan, P.; Krishnan, R.; Wen, C. Y.

    1977-01-01

    A general mathematical model for the prediction of performance of a fluidized bed coal combustor (FBC) is developed. The basic elements of the model consist of: (1) hydrodynamics of gas and solids in the combustor; (2) description of gas and solids contacting pattern; (3) kinetics of combustion; and (4) absorption of SO2 by limestone in the bed. The model is capable of calculating the combustion efficiency, axial bed temperature profile, carbon hold-up in the bed, oxygen and SO2 concentrations in the bubble and emulsion phases, sulfur retention efficiency and particulate carry over by elutriation. The effects of bed geometry, excess air, location of heat transfer coils in the bed, calcium to sulfur ratio in the feeds, etc. are examined. The calculated results are compared with experimental data. Agreement between the calculated results and the observed data are satisfactory in most cases. Recommendations to enhance the accuracy of prediction of the model are suggested.

  12. Effects of hydraulic roughness on surface textures of gravel-bed rivers

    Treesearch

    John M. Buffington; David R. Montgomery

    1999-01-01

    Field studies of forest gravel-bed rivers in northwestern Washington and southeastern Alaska demonstrate that bed-surface grain size is responsive to hydraulic roughness caused by bank irregularities, bars, and wood debris. We evaluate textural response by comparing reach-average median grain size (D50) to that predicted from the total bank-full boundary shear stress (...

  13. Investigation of Orbital Debris: Mitigation, Removal, and Modeling the Debris Population

    NASA Astrophysics Data System (ADS)

    Slotten, Joel

    The population of objects in orbit around Earth has grown since the late 1950s. Today there are over 21,000 objects over 10 cm in length in orbit, and an estimated 500,000 more between 1 and 10 cm. Only a small fraction of these objects are operational satellites. The rest are debris: old derelict spacecraft or rocket bodies, fragments created as the result of explosions or collisions, discarded objects, slag from solid rockets, or even flaked off paint. Traveling at up to 7 km/s, a collision with even a 1 cm piece of debris could severely damage or destroy a satellite. This dissertation examines three aspects of orbital debris. First, the concept of a self-consuming satellite is explored. This nanosatellite would use its own external structure as propellant to execute a deorbit maneuver at the end of its operational life, thus allowing it to meet current debris mitigation standards. Results from lab experiments examining potential materials for this concept have shown favorable results. Second, Particle in Cell techniques are modified and used to model the plasma plume from a micro-cathode arc thruster. This model is then applied to the concept of an ion beam shepherd satellite. This satellite would use its plasma plume to deorbit another derelict satellite. Results from these simulations indicate the micro-cathode arc thruster could potentially deorbit a derelict CubeSat in a matter of a few weeks. Finally, the orbital debris population at geosynchronous orbit is examined, focusing on variations in the density of the population as a function of longitude. New insights are revealed demonstrating that the variation in population density is slightly less than previously reported.

  14. Three occurred debris flows in North-Eastern Italian Alps: documentation and modeling

    NASA Astrophysics Data System (ADS)

    Boreggio, Mauro; Gregoretti, Carlo; Degetto, Massimo; Bernard, Martino

    2015-04-01

    Three occurred events of debris flows are documented and modeled by back-analysis. The three debris flows events are those occurred at Rio Lazer on the 4th of November 1966, at Fiames on the 5th of July 2006 and at Rovina di Cancia on the 18th of July 2009. All the three sites are located in the North-Eastern Italian Alps. In all the events, runoff entrained sediments present on natural channels and formed a solid-liquid wave that routed downstream. The first event concerns the routing of debris flow on an inhabited fan. Map of deposition pattern of sediments are built by using post-events photos through stereoscopy techniques. The second event concerns the routing of debris flow along the main channel descending from Pomagagnon Fork. Due to the obstruction of the cross-section debris flow deviated from the original path on the left side and routed downstream by cutting a new channel on the fan. It dispersed in multiple paths when met the wooden area. Map of erosion and deposition depths are built after using a combination of Lidar and GPS data. The third event concerns the routing of debris flow in the Rovina di Cancia channel that filled the reservoir built at the end of the channel and locally overtopped the retaining wall on the left side. A wave of mud and debris inundated the area downstream the overtopping point. Map of erosion and deposition depths are obtained by subtracting two GPS surveys, pre and post event. All the three occurred debris flows are simulated by modeling runoff that entrained debris flow for determining the solid-liquid hydrograph downstream the triggering areas. The routing of the solid-liquid hydrograph was simulated by a bi-phase cell model based on the kinematic approach. The comparison between simulated and measured erosion and deposition depths is satisfactory. The same parameters for computing erosion and deposition were used for the three occurred events.

  15. Response of a Brook Trout Population and Instream Habitat to a Catastrophic Flood and Debris Flow

    Treesearch

    Criag N. Roghair; C. Andrew Dolloff; Martin K. Underwood

    2002-01-01

    In June 1995, a massive flood and debris flow impacted fish and habitat along the lower 1.9 km of the Staunton River, a headwater stream located in Shenandoah National Park, Virginia. In the area affected by debris flow, the stream bed was scoured and new substrate materials were deposited, trees were removed from a 30-m-wide band in the riparian area, and all fish...

  16. In situ measurements of post-fire debris flows in southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions

    USGS Publications Warehouse

    Kean, J.W.; Staley, D.M.; Cannon, S.H.

    2011-01-01

    Debris flows often occur in burned steeplands of southern California, sometimes causing property damage and loss of life. In an effort to better understand the hydrologic controls on post-fire debris-flow initiation, timing and magnitude, we measured the flow stage, rainfall, channel bed pore fluid pressure and hillslope soil-moisture accompanying 24 debris flows recorded in five different watersheds burned in the 2009 Station and Jesusita Fires (San Gabriel and Santa Ynez Mountains). The measurements show substantial differences in debris-flow dynamics between sites and between sequential events at the same site. Despite these differences, the timing and magnitude of all events were consistently associated with local peaks in short duration (< = 30 min) rainfall intensity. Overall, debris-flow stage was best cross-correlated with time series of 5-min rainfall intensity, and lagged the rainfall by an average of just 5 min. An index of debris-flow volume was also best correlated with short-duration rainfall intensity, but found to be poorly correlated with storm cumulative rainfall and hillslope soil water content. Post-event observations of erosion and slope stability modeling suggest that the debris flows initiated primarily by processes related to surface water runoff, rather than shallow landslides. By identifying the storm characteristics most closely associated with post-fire debris flows, these measurements provide valuable guidance for warning operations and important constraints for developing and testing models of post-fire debris flows. copyright. 2011 by the American Geophysical Union.

  17. Method and apparatus for a combination moving bed thermal treatment reactor and moving bed filter

    DOEpatents

    Badger, Phillip C.; Dunn, Jr., Kenneth J.

    2015-09-01

    A moving bed gasification/thermal treatment reactor includes a geometry in which moving bed reactor particles serve as both a moving bed filter and a heat carrier to provide thermal energy for thermal treatment reactions, such that the moving bed filter and the heat carrier are one and the same to remove solid particulates or droplets generated by thermal treatment processes or injected into the moving bed filter from other sources.

  18. High frequency seismic monitoring of debris flows at Chalk Cliffs (CO), USA

    NASA Astrophysics Data System (ADS)

    Coviello, Velio; Kean, Jason; Smith, Joel; Coe, Jeffrey; Arattano, Massimo; McCoy, Scott

    2015-04-01

    A growing number of studies adopt passive seismic monitoring techniques to investigate slope instabilities and landslide processes. These techniques are attractive and convenient because large areas can be monitored from a safe distance. This is particularly true when the phenomena under investigation are rapid and infrequent mass movements like debris flows. Different types of devices are used to monitor debris flow processes, but among them ground vibration detectors (GVDs) present several, specific advantages that encourage their use. These advantages include: (i) the possibility to be installed outside the channel bed, (ii) the high adaptability to different and harsh field conditions, and (iii) the capability to detect the debris flow front arrival tens of seconds earlier than contact and stage sensors. Ground vibration data can provide relevant information on the dynamics of debris flows such as timing and velocity of the main surges. However, the processing of the raw seismic signal is usually needed, both to obtain a more effective representation of waveforms and to decrease the amount of data that need to be recorded and analyzed. With this objective, the methods of Amplitude and Impulses are commonly adopted to transform the raw signal to a 1-Hz signal that allows for a more useful representation of the phenomenon. In that way, peaks and other features become more visible and comparable with data obtained from other monitoring devices. In this work, we present the first debris flows seismic recordings gathered in the Chalk Cliffs instrumented basin, central Colorado, USA. In May 2014, two 4.5-Hz, three-axial geophones were installed in the upper part of the catchment. Seismic data are sampled at 333 Hz and then recorded by a standalone recording unit. One geophone is directly installed on bedrock, the other one mounted on a 1-m boulder partially buried in colluvium. This latter sensor integrates a heavily instrumented cross-section consisting of a 225 cm2

  19. Mechanics of debris flows and rock avalanches: Chapter 43

    USGS Publications Warehouse

    Iverson, Richard M.; Fernando, Harindra Joseph

    2012-01-01

    Debris flows are geophysical phenomena intermediate in character between rock avalanches and flash floods. They commonly originate as water-laden landslides on steep slopes and transform into liquefied masses of fragmented rock, muddy water, and entrained organic matter that disgorge from canyons onto valley floors. Typically including 50%–70% solid grains by volume, attaining speeds >10 m/s, and ranging in size up to ∼109 m3, debris flows can denude mountainsides, inundate floodplains, and devastate people and property (Figure 43.1). Notable recent debris-flow disasters resulted in more than 20,000 fatalities in Armero, Colombia, in 1985 and in Vargas state, Venezuela, in 1999.

  20. Staged cascade fluidized bed combustor

    DOEpatents

    Cannon, Joseph N.; De Lucia, David E.; Jackson, William M.; Porter, James H.

    1984-01-01

    A fluid bed combustor comprising a plurality of fluidized bed stages interconnected by downcomers providing controlled solids transfer from stage to stage. Each stage is formed from a number of heat transfer tubes carried by a multiapertured web which passes fluidizing air to upper stages. The combustor cross section is tapered inwardly from the middle towards the top and bottom ends. Sorbent materials, as well as non-volatile solid fuels, are added to the top stages of the combustor, and volatile solid fuels are added at an intermediate stage.

  1. Combined fluidized bed retort and combustor

    DOEpatents

    Shang, Jer-Yu; Notestein, John E.; Mei, Joseph S.; Zeng, Li-Wen

    1984-01-01

    The present invention is directed to a combined fluidized bed retorting and combustion system particularly useful for extracting energy values from oil shale. The oil-shale retort and combustor are disposed side-by-side and in registry with one another through passageways in a partition therebetween. The passageways in the partition are submerged below the top of the respective fluid beds to preclude admixing or the product gases from the two chambers. The solid oil shale or bed material is transported through the chambers by inclining or slanting the fluidizing medium distributor so that the solid bed material, when fluidized, moves in the direction of the downward slope of the distributor.

  2. Air-drying beds reduce the quantities of antibiotic resistance genes and class 1 integrons in residual municipal wastewater solids.

    PubMed

    Burch, Tucker R; Sadowsky, Michael J; LaPara, Timothy M

    2013-09-03

    This study investigated whether air-drying beds reduce antibiotic resistance gene (ARG) concentrations in residual municipal wastewater solids. Three laboratory-scale drying beds were operated for a period of nearly 100 days. Real-time PCR was used to quantify 16S rRNA genes, 16S rRNA genes specific to fecal bacteria (AllBac) and human fecal bacteria (HF183), the integrase gene of class 1 integrons (intI1), and five ARGs representing a cross-section of antibiotic classes and resistance mechanisms (erm(B), sul1, tet(A), tet(W), and tet(X)). Air-drying beds were capable of reducing all gene target concentrations by 1 to 5 orders of magnitude, and the nature of this reduction was consistent with both a net decrease in the number of bacterial cells and a lack of selection within the microbial community. Half-lives varied between 1.5 d (HF183) and 5.4 d (tet(X)) during the first 20 d of treatment. After the first 20 d of treatment, however, half-lives varied between 8.6 d (tet(X)) and 19.3 d (AllBac), and 16S rRNA gene, intI1, and sul1 concentrations did not change (P > 0.05). These results demonstrate that air-drying beds can reduce ARG and intI1 concentrations in residual municipal wastewater solids within timeframes typical of operating practices.

  3. Evolution of Fine-Grained Channel Margin Deposits behind Large Woody Debris in an Experimental Gravel-Bed Flume

    NASA Astrophysics Data System (ADS)

    ONeill, B.; Marks, S.; Skalak, K.; Puleo, J. A.; Wilcock, P. R.; Pizzuto, J. E.

    2014-12-01

    Fine grained channel margin (FGCM) deposits of the South River, Virginia sequester a substantial volume of fine-grained sediment behind large woody debris (LWD). FGCM deposits were created in a laboratory setting meant to simulate the South River environment using a recirculating flume (15m long by 0.6m wide) with a fixed gravel bed and adjustable slope (set to 0.0067) to determine how fine sediment is transported and deposited behind LWD. Two model LWD structures were placed 3.7 m apart on opposite sides of the flume. A wire mesh screen with attached wooden dowels simulated LWD with an upstream facing rootwad. Six experiments with three different discharge rates, each with low and high sediment concentrations, were run. Suspended sediment was very fine grained (median grain size of 3 phi) and well sorted (0.45 phi) sand. Upstream of the wood, water depths averaged about 0.08m, velocities averaged about 0.3 m/s, and Froude numbers averaged around 0.3. Downstream of the first LWD structure, velocities were reduced tenfold. Small amounts of sediment passed through the rootwad and fell out of suspension in the area of reduced flow behind LWD, but most of the sediment was carried around the LWD by the main flow and then behind the LWD by a recirculating eddy current. Upstream migrating dunes formed behind LWD due to recirculating flow, similar to reattachment bars documented in bedrock canyon rivers partially obstructed by debouching debris fans. These upstream migrating dunes began at the reattachment point and merged with deposits formed from sediment transported through the rootwad. Downstream migrating dunes formed along the channel margin behind the LWD, downstream of the reattachment point. FGCM deposits were about 3 m long, with average widths of about 0.8 m. Greater sediment concentration created thicker FGCM deposits, and higher flows eroded the sides of the deposits, reducing their widths.

  4. Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sun, Rui, E-mail: Sunsr@hit.edu.cn; Ismail, Tamer M., E-mail: temoil@aucegypt.edu; Ren, Xiaohan

    Highlights: • The effects of moisture content on the burning process of MSW are investigated. • A two-dimensional mathematical model was built to simulate the combustion process. • Temperature distributions, process rates, gas species were measured and simulated. • The The conversion ratio of C/CO and N/NO in MSW are inverse to moisture content. - Abstract: In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on themore » combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k–ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW.« less

  5. Apparatus for controlling fluidized beds

    DOEpatents

    Rehmat, A.G.; Patel, J.G.

    1987-05-12

    An apparatus and process are disclosed for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance. 2 figs.

  6. Apparatus for controlling fluidized beds

    DOEpatents

    Rehmat, Amirali G.; Patel, Jitendra G.

    1987-05-12

    An apparatus and process for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance.

  7. Measurement of solids motion in gas-fluidized beds. Technical progress report, 1 October 1982-31 December 1982

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, M.M.; Chao, B.T.

    This technical progress report covers the progress made during the fifth quarter of the project entitled Measurements of Solids Motion in Gas Fluidized Beds under Grant No. DOE-F22-81PC40804 during the period 1 October through 31 December 1982. The research concerns the measurement of solids particle velocity distribution and residence time distribution using the Computer-Aided Particle Tracking Facility (CAPTF) at the University of Illinois at Urbana-Champaign. The experimental equipment and measuring methods used to determine particle size distribution and particle motion and the results obtained are presented.

  8. The influence of process parameters in production of lipopeptide iturin A using aerated packed bed bioreactors in solid-state fermentation.

    PubMed

    Piedrahíta-Aguirre, C A; Bastos, R G; Carvalho, A L; Monte Alegre, R

    2014-08-01

    The strain Bacillus iso 1 co-produces the lipopeptide iturin A and biopolymer poly-γ-glutamic acid (γ-PGA) in solid-state fermentation of substrate consisting of soybean meal, wheat bran with rice husks as an inert support. The effects of pressure drop, oxygen consumption, medium permeability and temperature profile were studied in an aerated packed bed bioreactor to produce iturin A, diameter of which was 50 mm and bed height 300 mm. The highest concentrations of iturin A and γ-PGA were 5.58 and 3.58 g/kg-dry substrate, respectively, at 0.4 L/min after 96 h of fermentation. The low oxygen uptake rates, being 23.34 and 22.56 mg O2/kg-dry solid substrate for each air flow rate tested generated 5.75 W/kg-dry substrate that increased the fermentation temperature at 3.7 °C. The highest pressure drop was 561 Pa/m at 0.8 L/min in 24 h. This is the highest concentration of iturin A produced to date in an aerated packed bed bioreactor in solid-state fermentation. The results can be useful to design strategies to scale-up process of iturin A in aerated packed bed bioreactors. Low concentration of γ-PGA affected seriously pressure drop, decreasing the viability of the process due to generation of huge pressure gradients with volumetric air flow rates. Also, the low oxygenation favored the iturin A production due to the reduction of free void by γ-PGA production, and finally, the low oxygen consumption generated low metabolic heat. The results show that it must control the pressure gradients to scale-up the process of iturin A production.

  9. Effects of hydraulic roughness on surface textures of gravel‐bed rivers

    USGS Publications Warehouse

    Buffington, John M.; Montgomery, David R.

    1999-01-01

    Field studies of forest gravel‐bed rivers in northwestern Washington and southeastern Alaska demonstrate that bed‐surface grain size is responsive to hydraulic roughness caused by bank irregularities, bars, and wood debris. We evaluate textural response by comparing reach‐average median grain size (D50) to that predicted from the total bank‐full boundary shear stress (т0bf), representing a hypothetical reference condition of low hydraulic roughness. For a given т0bf, channels with progressively greater hydraulic roughness have systematically finer bed surfaces, presumably due to reduced bed shear stress, resulting in lower channel competence and diminished bed load transport capacity, both of which promote textural fining. In channels with significant hydraulic roughness, observed values D50 can be up to 90% smaller than those predicted from т0bf. We find that wood debris plays an important role at our study sites, not only providing hydraulic roughness but also influencing pool spacing, frequency of textural patches, and the amplitude and wavelength of bank and bar topography and their consequent roughness. Our observations also have biological implications. We find that textural fining due to hydraulic roughness can create usable salmonid spawning gravels in channels that otherwise would be too coarse.

  10. Mathematical modelling of particle mixing effect on the combustion of municipal solid wastes in a packed-bed furnace.

    PubMed

    Yang, Yao Bin; Swithenbank, Jim

    2008-01-01

    Packed bed combustion is still the most common way to burn municipal solid wastes. In this paper, a dispersion model for particle mixing, mainly caused by the movement of the grate in a moving-burning bed, has been proposed and transport equations for the continuity, momentum, species, and energy conservation are described. Particle-mixing coefficients obtained from model tests range from 2.0x10(-6) to 3.0x10(-5)m2/s. A numerical solution is sought to simulate the combustion behaviour of a full-scale 12-tonne-per-h waste incineration furnace at different levels of bed mixing. It is found that an increase in mixing causes a slight delay in the bed ignition but greatly enhances the combustion processes during the main combustion period in the bed. A medium-level mixing produces a combustion profile that is positioned more at the central part of the combustion chamber, and any leftover combustible gases (mainly CO) enter directly into the most intensive turbulence area created by the opposing secondary-air jets and thus are consumed quickly. Generally, the specific arrangement of the impinging secondary-air jets dumps most of the non-uniformity in temperature and CO into the gas flow coming from the bed-top, while medium-level mixing results in the lowest CO emission at the furnace exit and the highest combustion efficiency in the bed.

  11. Coupling scales for modelling heavy metal vaporization from municipal solid waste incineration in a fluid bed by CFD.

    PubMed

    Soria, José; Gauthier, Daniel; Flamant, Gilles; Rodriguez, Rosa; Mazza, Germán

    2015-09-01

    Municipal Solid Waste Incineration (MSWI) in fluidized bed is a very interesting technology mainly due to high combustion efficiency, great flexibility for treating several types of waste fuels and reduction in pollutants emitted with the flue gas. However, there is a great concern with respect to the fate of heavy metals (HM) contained in MSW and their environmental impact. In this study, a coupled two-scale CFD model was developed for MSWI in a bubbling fluidized bed. It presents an original scheme that combines a single particle model and a global fluidized bed model in order to represent the HM vaporization during MSW combustion. Two of the most representative HM (Cd and Pb) with bed temperatures ranging between 923 and 1073K have been considered. This new approach uses ANSYS FLUENT 14.0 as the modelling platform for the simulations along with a complete set of self-developed user-defined functions (UDFs). The simulation results are compared to the experimental data obtained previously by the research group in a lab-scale fluid bed incinerator. The comparison indicates that the proposed CFD model predicts well the evolution of the HM release for the bed temperatures analyzed. It shows that both bed temperature and bed dynamics have influence on the HM vaporization rate. It can be concluded that CFD is a rigorous tool that provides valuable information about HM vaporization and that the original two-scale simulation scheme adopted allows to better represent the actual particle behavior in a fluid bed incinerator. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Effects of process parameters on solid self-microemulsifying particles in a laboratory scale fluid bed.

    PubMed

    Mukherjee, Tusharmouli; Plakogiannis, Fotios M

    2012-01-01

    The purpose of this study was to select the critical process parameters of the fluid bed processes impacting the quality attribute of a solid self-microemulsifying (SME) system of albendazole (ABZ). A fractional factorial design (2(4-1)) with four parameters (spray rate, inlet air temperature, inlet air flow, and atomization air pressure) was created by MINITAB software. Batches were manufactured in a laboratory top-spray fluid bed at 625-g scale. Loss on drying (LOD) samples were taken throughout each batch to build the entire moisture profiles. All dried granulation were sieved using mesh 20 and analyzed for particle size distribution (PSD), morphology, density, and flow. It was found that as spray rate increased, sauter-mean diameter (D(s)) also increased. The effect of inlet air temperature on the peak moisture which is directly related to the mean particle size was found to be significant. There were two-way interactions between studied process parameters. The main effects of inlet air flow rate and atomization air pressure could not be found as the data were inconclusive. The partial least square (PLS) regression model was found significant (P < 0.01) and predictive for optimization. This study established a design space for the parameters for solid SME manufacturing process.

  13. Study on the leaching behavior of actinides from nuclear fuel debris

    NASA Astrophysics Data System (ADS)

    Kirishima, Akira; Hirano, Masahiko; Akiyama, Daisuke; Sasaki, Takayuki; Sato, Nobuaki

    2018-04-01

    For the prediction of the leaching behavior of actinides contained in the nuclear fuel debris generated by the Fukushima Daiichi nuclear power plant accident in Japan, simulated fuel debris consisting of a UO2-ZrO2 solid solution doped with 137Cs, 237Np, 236Pu, and 241Am tracers was synthesized and investigated. The synthesis of the debris was carried out by heat treatment at 1200 °C at different oxygen partial pressures, and the samples were subsequently used for leaching tests with Milli-Q water and seawater. The results of the leaching tests indicate that the leaching of actinides depends on the redox conditions under which the debris was generated; for example, debris generated under oxidative conditions releases more actinide nuclides to water than that generated under reductive conditions. Furthermore, we found that, as Zr(IV) increasingly substituted U(IV) in the fluorite crystal structure of the debris, the actinide leaching from the debris decreased. In addition, we found that seawater leached more actinides from the debris than pure water, which seems to be caused by the complexation of actinides by carbonate ions in seawater.

  14. Dual fluidized bed design for the fast pyrolysis of biomass

    USDA-ARS?s Scientific Manuscript database

    A mechanism for the transport of solids between fluidised beds in dual fluidised bed systems for the fast pyrolysis of biomass process was selected. This mechanism makes use of an overflow standpipe to transport solids from the fluidised bed used for the combustion reactions to a second fluidised be...

  15. Design of fluidized-bed fermentors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Andrews, G.F.; Przezdziecki, J.

    1986-06-01

    Designing a fluidized-bed bioreactor requires choosing the best support particle (if any). Effectiveness factors (proportional to reactor volumetric productivity) are derived for flocs, solid spherical supports, porous supports, and adsorbent supports. The derivation demonstrates a mathematical procedure for reducing the diffusion/uptake equations for many components (substrates and inhibitory products) to a single equation, and for identifying the limiting component. With solid supports there exists a film thickness that maximizes the effectiveness, and the design objective is to keep the film near this optimum throughout the bed. This involves consideration of the effect of support particle density and film growth onmore » bed stratification. Other considerations in packing support particles are obtaining reasonable values for bed height and diameter, minimizing mass transfer resistance between liquid and biomass, and preventing surface shear from stripping off the biomass. 20 references.« less

  16. Staged fluidized-bed combustion and filter system

    DOEpatents

    Mei, Joseph S.; Halow, John S.

    1994-01-01

    A staged fluidized-bed combustion and filter system for substantially reducing the quantity of waste through the complete combustion into ash-type solids and gaseous products. The device has two fluidized-bed portions, the first primarily as a combustor/pyrolyzer bed, and the second as a combustor/filter bed. The two portions each have internal baffles to define stages so that material moving therein as fluidized beds travel in an extended route through those stages. Fluidization and movement is achieved by the introduction of gases into each stage through a directional nozzle. Gases produced in the combustor/pyrolyzer bed are permitted to travel into corresponding stages of the combustor/filter bed through screen filters that permit gas flow but inhibit solids flow. Any catalyst used in the combustor/filter bed is recycled. The two beds share a common wall to minimize total volume of the system. A slightly modified embodiment can be used for hot gas desulfurization and sorbent regeneration. Either side-by-side rectangular beds or concentric beds can be used. The system is particularly suited to the processing of radioactive and chemically hazardous waste.

  17. Modeling four occurred debris flow events in the Dolomites area (North-Eastern Italian Alps)

    NASA Astrophysics Data System (ADS)

    Boreggio, Mauro; Gregoretti, Carlo; Degetto, Massimo; Bernard, Martino

    2016-04-01

    Four occurred debris flows in the Dolomites area (North-Eastern Italian Alps) are modeled by back-analysis. The four debris flows events are those occurred at Rio Lazer (Trento) on the 4th of November 1966, at Fiames (Belluno) on the 5th of July 2006, at Rovina di Cancia (Belluno) on the 18th of July 2009 and at Rio Val Molinara (Trento) on the 15th of August 2010. In all the events, runoff entrained sediments present on natural channels and formed a solid-liquid wave that routed downstream. The first event concerns the routing of debris flow on an inhabited fan. The second event the deviation of debris flow from the usual path due to an obstruction with the excavation of a channel in the scree and the downstream spreading in a wood. The third event concerns the routing of debris flow in a channel with an ending the reservoir, its overtopping and final spreading in the inhabited area. The fourth event concerns the routing of debris flow along the main channel downstream the initiation area until spreading just upstream a village. All the four occurred debris flows are simulated by modeling runoff that entrained debris flow for determining the solid-liquid hydrograph. The routing of the solid-liquid hydrograph is simulated by a bi-phase cell model based on the kinematic approach. The comparison between simulated and measured erosion and deposition depths is satisfactory. Nearly the same parameters for computing erosion and deposition were used for all the four occurred events. The maps of erosion and deposition depths are obtained by comparing the results of post-event surveys with the pre-event DEM. The post-event surveys were conducted by using different instruments (LiDAR and GPS) or the combination photos-single points depth measurements (in this last case it is possible obtaining the deposition/erosion depths by means of stereoscopy techniques).

  18. Characterization of Debris from the DebriSat Hypervelocity Test

    NASA Technical Reports Server (NTRS)

    Rivero, M.; Kleespies, J.; Patankar, K.; Fitz-Coy, N.; Liou, J.-C.; Sorge, M.; Huynh, T.; Opiela, J.; Krisko, P.; Cowardin, H.

    2015-01-01

    The DebriSat project is an effort by NASA and the DoD to update the standard break-up model for objects in orbit. The DebriSat object, a 56 kg representative LEO satellite, was subjected to a hypervelocity impact in April 2014. For the hypervelocity test, the representative satellite was suspended within a "soft-catch" arena formed by polyurethane foam panels to minimize the interactions between the debris generated from the hypervelocity impact and the metallic walls of the test chamber. After the impact, the foam panels and debris not caught by the panels were collected and shipped to the University of Florida where the project has now advanced to the debris characterization stage. The characterization effort has been divided into debris collection, measurement, and cataloguing. Debris collection and cataloguing involves the retrieval of debris from the foam panels and cataloguing the debris in a database. Debris collection is a three-step process: removal of loose debris fragments from the surface of the foam panels; X-ray imaging to identify/locate debris fragments embedded within the foam panel; extraction of the embedded debris fragments identified during the X-ray imaging process. As debris fragments are collected, they are catalogued into a database specifically designed for this project. Measurement involves determination of size, mass, shape, material, and other physical properties and well as images of the fragment. Cataloguing involves a assigning a unique identifier for each fragment along with the characterization information.

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

    NASA Astrophysics Data System (ADS)

    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

  20. Volatile organic compound adsorption in a gas-solid fluidized bed.

    PubMed

    Ng, Y L; Yan, R; Tsen, L T S; Yong, L C; Liu, M; Liang, D T

    2004-01-01

    Fluidization finds many process applications in the areas of catalytic reactions, drying, coating, combustion, gasification and microbial culturing. This work aims to compare the dynamic adsorption characteristics and adsorption rates in a bubbling fluidized bed and a fixed bed at the same gas flow-rate, gas residence time and bed height. Adsorption with 520 ppm methanol and 489 ppm isobutane by the ZSM-5 zeolite of different particle size in the two beds enabled the differentiation of the adsorption characteristics and rates due to bed type, intraparticle mass transfer and adsorbate-adsorbent interaction. Adsorption of isobutane by the more commonly used activated carbon provided the comparison of adsorption between the two adsorbent types. With the same gas residence time of 0.79 seconds in both the bubbling bed and fixed bed of the same bed size of 40 mm diameter and 48 mm height, the experimental results showed a higher rate of adsorption in the bubbling bed as compared to the fixed bed. Intraparticle mass transfer and adsorbent-adsorbate interaction played significant roles in affecting the rate of adsorption, with intraparticle mass transfer being more dominant. The bubbling bed was observed to have a steeper decline in adsorption rate with respect to increasing outlet concentration compared to the fixed bed. The adsorption capacities of zeolite for the adsorbates studied were comparatively similar in both beds; fluidizing, and using smaller particles in the bubbling bed did not increase the adsorption capacity of the ZSM-5 zeolite. The adsorption capacity of activated carbon for isobutane was much higher than the ZSM-5 zeolite for isobutane, although at a lower adsorption rate. Fourier transform infra-red (FTIR) spectroscopy was used as an analytical tool for the quantification of gas concentration. Calibration was done using a series of standards prepared by in situ dilution with nitrogen gas, based on the ideal gas law and relating partial pressure to gas

  1. Debris flows resulting from glacial-lake outburst floods in tibet, China

    USGS Publications Warehouse

    Cui, P.; Dang, C.; Cheng, Z.; Scott, K.

    2010-01-01

    During the last 70 years of general climatic amelioration, 18 glacial-lake outburst floods (GLOFs) and related debris flows have occurred from 15 moraine-dammed lakes in Tibet, China. Catastrophic loss of life and property has occurred because of the following factors: the large volumes of water discharged, the steep gradients of the U-shaped channels, and the amount and texture of the downstream channel bed and bank material. The peak discharge of each GLOF exceeded 1000 m3/s. These flood discharges transformed to non-cohesive debris flows if the channels contained sufficient loose sediment for entrainment (bulking) and if their gradients were >1%. We focus on this key element, transformation, and suggest that it be included in evaluating future GLOF-related risk, the probability of transformation to debris flow and hyperconcentrated flow. The general, sequential evolution of the flows can be described as from proximal GLOFs, to sedimentladen streamflow, to hyperconcentrated flow, to non-cohesive debris flow (viscous or cohesive debris flow only if sufficient fine sediment is present), and then, distally, back to hyperconcentrated flow and sediment-laden streamflow as sediment is progressively deposited. Most of the Tibet examples transformed only to non-cohesive debris flows. The important lesson for future hazard assessment and mitigation planning is that, as a GLOF entrains (bulks) enough sediment to become a debris flow, the flow volume must increase by at least three times (the "bulking factor"). In fact, the transforming flow waves overrun and mix with downstream streamflow, in addition to adding the entrained sediment (and thus enabling addition of yet more sediment and a bulking factor in excess of three times). To effectively reduce the risk of GLOF debris flows, reducing the level of a potentially dangerous lake with a siphon or excavated spillway or installing gabions in combination with a downstream debris dam are the primary approaches.

  2. Investigation of CO 2 capture using solid sorbents in a fluidized bed reactor: Cold flow hydrodynamics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Tingwen; Dietiker, Jean -Francois; Rogers, William

    2016-07-29

    Both experimental tests and numerical simulations were conducted to investigate the fluidization behavior of a solid CO 2 sorbent with a mean diameter of 100 μm and density of about 480 kg/m, which belongs to Geldart's Group A powder. A carefully designed fluidized bed facility was used to perform a series of experimental tests to study the flow hydrodynamics. Numerical simulations using the two-fluid model indicated that the grid resolution has a significant impact on the bed expansion and bubbling flow behavior. Due to the limited computational resource, no good grid independent results were achieved using the standard models asmore » far as the bed expansion is concerned. In addition, all simulations tended to under-predict the bubble size substantially. Effects of various model settings including both numerical and physical parameters have been investigated with no significant improvement observed. The latest filtered sub-grid drag model was then tested in the numerical simulations. Compared to the standard drag model, the filtered drag model with two markers not only predicted reasonable bed expansion but also yielded realistic bubbling behavior. As a result, a grid sensitivity study was conducted for the filtered sub-grid model and its applicability and limitation were discussed.« less

  3. A CFD model for biomass combustion in a packed bed furnace

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Karim, Md. Rezwanul; Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704; Ovi, Ifat Rabbil Qudrat

    Climate change has now become an important issue which is affecting environment and people around the world. Global warming is the main reason of climate change which is increasing day by day due to the growing demand of energy in developed countries. Use of renewable energy is now an established technique to decrease the adverse effect of global warming. Biomass is a widely accessible renewable energy source which reduces CO{sub 2} emissions for producing thermal energy or electricity. But the combustion of biomass is complex due its large variations and physical structures. Packed bed or fixed bed combustion is themore » most common method for the energy conversion of biomass. Experimental investigation of packed bed biomass combustion is difficult as the data collection inside the bed is challenging. CFD simulation of these combustion systems can be helpful to investigate different operational conditions and to evaluate the local values inside the investigation area. Available CFD codes can model the gas phase combustion but it can’t model the solid phase of biomass conversion. In this work, a complete three-dimensional CFD model is presented for numerical investigation of packed bed biomass combustion. The model describes the solid phase along with the interface between solid and gas phase. It also includes the bed shrinkage due to the continuous movement of the bed during solid fuel combustion. Several variables are employed to represent different parameters of solid mass. Packed bed is considered as a porous bed and User Defined Functions (UDFs) platform is used to introduce solid phase user defined variables in the CFD. Modified standard discrete transfer radiation method (DTRM) is applied to model the radiation heat transfer. Preliminary results of gas phase velocity and pressure drop over packed bed have been shown. The model can be useful for investigation of movement of the packed bed during solid fuel combustion.« less

  4. Internal characteristics of refractive-index matched debris flows

    NASA Astrophysics Data System (ADS)

    Gollin, Devis; Bowman, Elisabeth; Sanvitale, Nicoletta

    2016-04-01

    Debris flows are channelized masses of granular material saturated with water that travel at high speeds downslope. Their destructive character represents a hazard to lives and properties, especially in regions of high relief and runoff. The characteristics that distinguish their heterogeneous, multi-phase, nature are numerous: non-uniform surge formation, particle size ranging from clay to boulders, flow segregation with larger particles concentrating at the flow front and fluid at the tail making the composition and volume of the bulk varying with time and space. These aspects render these events very difficult to characterise and predict, in particular in the area of the deposit spread or runout - zones which are generally of most interest in terms of human risk. At present, considerable gaps exist in our understanding of the flow dynamics of debris flows, which originates from their complex motion and relatively poor observations available. Flume studies offer the potential to examine in detail the behaviour of model debris flows, however, the opaque nature of these flows is a major obstacle in gaining insight of their internal behaviour. Measurements taken at the sidewalls may be poorly representative leading to incomplete or misleading results. To probe internally to the bulk of the flow, alternative, nonintrusive techniques can be used, enabling, for instance, velocities and solid concentrations within the flowing material to be determined. We present experimental investigations into polydisperse granular flows of spherical immersed particles down an inclined flume, with specific attention directed to their internal behavior. To this end, the refractive indices of solids and liquid are closely matched allowing the two phases to be distinguished. Measurements are then made internally at a point in the channel via Plane Laser Induced Fluorescence, Particle Tracking Velocimetry, PTV and Particle Image Velocimetry, PIV. The objective is to to increase our

  5. Coupling scales for modelling heavy metal vaporization from municipal solid waste incineration in a fluid bed by CFD

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Soria, José, E-mail: jose.soria@probien.gob.ar; Gauthier, Daniel; Flamant, Gilles

    2015-09-15

    Highlights: • A CFD two-scale model is formulated to simulate heavy metal vaporization from waste incineration in fluidized beds. • MSW particle is modelled with the macroscopic particle model. • Influence of bed dynamics on HM vaporization is included. • CFD predicted results agree well with experimental data reported in literature. • This approach may be helpful for fluidized bed reactor modelling purposes. - Abstract: Municipal Solid Waste Incineration (MSWI) in fluidized bed is a very interesting technology mainly due to high combustion efficiency, great flexibility for treating several types of waste fuels and reduction in pollutants emitted with themore » flue gas. However, there is a great concern with respect to the fate of heavy metals (HM) contained in MSW and their environmental impact. In this study, a coupled two-scale CFD model was developed for MSWI in a bubbling fluidized bed. It presents an original scheme that combines a single particle model and a global fluidized bed model in order to represent the HM vaporization during MSW combustion. Two of the most representative HM (Cd and Pb) with bed temperatures ranging between 923 and 1073 K have been considered. This new approach uses ANSYS FLUENT 14.0 as the modelling platform for the simulations along with a complete set of self-developed user-defined functions (UDFs). The simulation results are compared to the experimental data obtained previously by the research group in a lab-scale fluid bed incinerator. The comparison indicates that the proposed CFD model predicts well the evolution of the HM release for the bed temperatures analyzed. It shows that both bed temperature and bed dynamics have influence on the HM vaporization rate. It can be concluded that CFD is a rigorous tool that provides valuable information about HM vaporization and that the original two-scale simulation scheme adopted allows to better represent the actual particle behavior in a fluid bed incinerator.« less

  6. Dynamic transition between fixed- and mobile-bed: mathematical and numerical aspects

    NASA Astrophysics Data System (ADS)

    Zugliani, Daniel; Pasqualini, Matteo; Rosatti, Giorgio

    2017-04-01

    Free-surface flows with high sediment transport (as debris flow or hyper-concentrated flow) are composed by a mixture of fluid and solid phase, usually water and sediment. When these flows propagate over loose beds, particles constituting the mixture of water and sediments strongly interact with the ones forming the bed, leading to erosion or deposition. However, there are lots of other situations when the mixture flows over rigid bedrocks or over artificially paved transects, so there is no mass exchange between bed and mixture. The two situations are usually referred to as, respectively, mobile- and fixed-bed conditions. From a mathematical point of view, the systems of Partial Differential Equations (PDEs) that describe these flows derive from mass and momentum balance of both phases, but, the two resulting PDEs systems are different. The main difference concerns the concentration: in the mobile-bed condition, the concentration is linked to the local flow conditions by means of a suitable rheological relation, while in the fixed-bed case, the concentration is an unknown of the problem. It is quite common that a free surface flow with high sediment transport, in its path, encounters both conditions. In the recent work of Rosatti & Zugliani 2015, the mathematical and numerical description of the transition between fixed- and mobile-bed was successfully resolved, for the case of low sediment transport phenomena, by the introduction of a suitable erodibility variable and satisfactory results were obtained. The main disadvantage of the approach is related to the erodibility variable, that changes in space, based on bed characteristics, but remains constant in time. However, the nature of the bed can change dynamically as result of deposition over fixed bed or high erosion over mobile bed. With this work, we extend the applicability of the mentioned approach to the more complex PDEs describing the hyper-concentrated flow. Moreover, we introduce a strategy that allows

  7. CFD-DEM study of effect of bed thickness for bubbling fluidized beds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tingwen, Li; Gopalakrishnan, Pradeep; Garg, Rahul

    2011-10-01

    The effect of bed thickness in rectangular fluidized beds is investigated through the CFD–DEM simulations of small-scale systems. Numerical results are compared for bubbling fluidized beds of various bed thicknesses with respect to particle packing, bed expansion, bubble behavior, solids velocities, and particle kinetic energy. Good two-dimensional (2D) flow behavior is observed in the bed having a thickness of up to 20 particle diameters. However, a strong three-dimensional (3D) flow behavior is observed in beds with a thickness of 40 particle diameters, indicating the transition from 2D flow to 3D flow within the range of 20–40 particle diameters. Comparison ofmore » velocity profiles near the walls and at the center of the bed shows significant impact of the front and back walls on the flow hydrodynamics of pseudo-2D fluidized beds. Hence, for quantitative comparison with experiments in pseudo-2D columns, the effect of walls has to be accounted for in numerical simulations.« less

  8. Debris disc constraints on planetesimal formation

    NASA Astrophysics Data System (ADS)

    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.

  9. Looking inside a debris flow

    NASA Astrophysics Data System (ADS)

    Bowman, Elisabeth; Sanvitale, Nicoletta; Bird, Joshua

    2014-05-01

    Debris flows, masses of saturated, channelized, granular materials that flow at high speeds downslope, present a hazard to lives and infrastructure in regions of high relief and runoff. They also present a challenge to modelling due to the heterogeneous, multi-phase, nature of the constituent materials, with particles ranging from boulder-size to silt-size and fluid viscosity being altered by the presence of fine particles and clay. As a debris flow travels on its flow path, it will tend to segregate, with larger particles being focused to the flow front and fluid being concentrated in the tail - resulting in different rheological behaviour in time and space. It will also tend to erode and deposit material as it moves through different channel segments or reaches, with this behaviour influenced by the confinement of the channel and the angle of the slope within each reach. Flume studies offer the potential to examine in detail the behaviour of model debris flows within the penultimate and final (deposit fan area) reaches - zones which are generally of most interest in terms of human risk. Flume studies which are conducted using transparent debris offer additional benefits to more traditional methods that use opaque materials, enabling insights to the flow behaviour that are inaccessible via other physical methods. We present flume model work which has been designed to capture some essential aspects of debris flow behaviour using well graded (polydisperse) transparent debris, albeit at reduced scale. These aspects include the final deposit spread or runout increasing for a lower concentration of solids and a higher penultimate reach slope angle, and observable particle size segregation during downslope motion. We present time-varying measurements made internally and externally at a point in the channel via Plane Laser Induced Fluorescence and Particle Image Velocimetry, PIV. The measurements enable velocity distributions of the segregating flows over time to be

  10. EMERGING TECHNOLOGY BULLETIN: SPOUTED BED REACTOR

    EPA Science Inventory

    The Spouted Bed Reactor (SBR) technology utilizes the unique attributes of the "spouting " fluidization regime, which can provide heat transfer rates comparable to traditional fluid beds, while providing robust circulation of highly heterogeneous solids, concurrent with very agg...

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

    NASA Astrophysics Data System (ADS)

    Amponsah, William

    2015-04-01

    values when considering the local runoff regime. We used a threshold criterion based on past works (Tognaccaet al., 2000; Berti and Simoni, 2005; Gregoretti and Dalla Fontana, 2008) to identify tributaries associated to debris flow events. The threshold is defined for each channel grid as a function of the simulated unit width peak flow, of the local channel bed slope and of the mean grain size. Based on assumptions concerning the mean grain size and given the distribution of the threshold values over the river network, we derive a catchment scale threshold index for the tributaries. The results show that the index has considerable skill in identifying the catchments where the studied rainstorm caused debris-flows. Berti, M. andA.Simoni, 2005: Experimental evidences and numerical modelling of debris flow initiated by channel runoff. Landslides, 2 (3), 171-182. Gregoretti, C. and G. Dalla Fontana, 2008:The triggering of debris flow due to channel-bed failure in some alpine headwater basins of the Dolomites: analyses of critical runoff. Hydrol. Process. 22, 2248-2263. Tognacca C., G.R. Bezzola andH.E.Minor, 2000: Threshold criterion fodebrisflow initiation due to channel bed failure. In Proceedings of the Second International Conference on Debris Flow Hazards Mitigation Taipei,August, Wiezczorek, Naeser (eds): 89-97.

  12. 20. View of sand filtration bed. Wheelbarrow was used to ...

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

    20. View of sand filtration bed. Wheelbarrow was used to remove schmutzdeck (top, dirty sand layer containing particulate contamination, dead microorganisms and debris) for cleaning and or disposal. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  13. Fluidized bed gasification of extracted coal

    DOEpatents

    Aquino, Dolores C.; DaPrato, Philip L.; Gouker, Toby R.; Knoer, Peter

    1986-01-01

    Coal or similar carbonaceous solids are extracted by contacting the solids in an extraction zone (12) with an aqueous solution having a pH above 12.0 at a temperature between 65.degree. C. and 110.degree. C. for a period of time sufficient to remove bitumens from the coal into said aqueous solution and the extracted solids are then gasified at an elevated pressure and temperature in a fluidized bed gasification zone (60) wherein the density of the fluidized bed is maintained at a value above 160 kg/m.sup.3. In a preferred embodiment of the invention, water is removed from the aqueous solution in order to redeposit the extracted bitumens onto the solids prior to the gasification step.

  14. Fluidized bed gasification of extracted coal

    DOEpatents

    Aquino, D.C.; DaPrato, P.L.; Gouker, T.R.; Knoer, P.

    1984-07-06

    Coal or similar carbonaceous solids are extracted by contacting the solids in an extraction zone with an aqueous solution having a pH above 12.0 at a temperature between 65/sup 0/C and 110/sup 0/C for a period of time sufficient to remove bitumens from the coal into said aqueous solution, and the extracted solids are then gasified at an elevated pressure and temperature in a fluidized bed gasification zone (60) wherein the density of the fluidized bed is maintained at a value above 160 kg/m/sup 3/. In a preferred embodiment of the invention, water is removed from the aqueous solution in order to redeposit the extracted bitumens onto the solids prior to the gasification step. 2 figs., 1 tab.

  15. Occurrence and persistence of fungicides in bed sediments and suspended solids from three targeted use areas in the United States

    USGS Publications Warehouse

    Smalling, Kelly L.; Reilly, Timothy J.; Sandstrom, Mark W.; Kuivila, Kathryn

    2013-01-01

    To document the environmental occurrence and persistence of fungicides, a robust and sensitive analytical method was used to measure 34 fungicides and an additional 57 current-use pesticides in bed sediments and suspended solids collected from areas of intense fungicide use within three geographic areas across the United States. Sampling sites were selected near or within agricultural research farms using prophylactic fungicides at rates and types typical of their geographic location. At least two fungicides were detected in 55% of the bed and 83% of the suspended solid samples and were detected in conjunction with herbicides and insecticides. Six fungicides were detected in all samples including pyraclostrobin (75%), boscalid (53%), chlorothalonil (41%) and zoxamide (22%). Pyraclostrobin, a strobilurin fungicide, used frequently in the United States on a variety of crops, was detected more frequently than p,p′-DDE, the primary degradate of p,p′-DDT, which is typically one of the most frequently occurring pesticides in sediments collected within highly agricultural areas. Maximum fungicide concentrations in bed sediments and suspended solids were 198 and 56.7 μg/kg dry weight, respectively. There is limited information on the occurrence, fate, and persistence of many fungicides in sediment and the environmental impacts are largely unknown. The results of this study indicate the importance of documenting the persistence of fungicides in the environment and the need for a better understanding of off-site transport mechanisms, particularly in areas where crops are grown that require frequent treatments to prevent fungal diseases.

  16. An integrated study to evaluate debris flow hazard in alpine environment

    NASA Astrophysics Data System (ADS)

    Tiranti, Davide; Crema, Stefano; Cavalli, Marco; Deangeli, Chiara

    2018-05-01

    Debris flows are among the most dangerous natural processes affecting the alpine environment due to their magnitude (volume of transported material) and the long runout. The presence of structures and infrastructures on alluvial fans can lead to severe problems in terms of interactions between debris flows and human activities. Risk mitigation in these areas requires identifying the magnitude, triggers, and propagation of debris flows. Here, we propose an integrated methodology to characterize these phenomena. The methodology consists of three complementary procedures. Firstly, we adopt a classification method based on the propensity of the catchment bedrocks to produce clayey-grained material. The classification allows us to identify the most likely rheology of the process. Secondly, we calculate a sediment connectivity index to estimate the topographic control on the possible coupling between the sediment source areas and the catchment channel network. This step allows for the assessment of the debris supply, which is most likely available for the channelized processes. Finally, with the data obtained in the previous steps, we modelled the propagation and depositional pattern of debris flows with a 3D code based on Cellular Automata. The results of the numerical runs allow us to identify the depositional patterns and the areas potentially involved in the flow processes. This integrated methodology is applied to a test-bed catchment located in Northwestern Alps. The results indicate that this approach can be regarded as a useful tool to estimate debris flow related potential hazard scenarios in an alpine environment in an expeditious way without possessing an exhaustive knowledge of the investigated catchment, including data on historical debris flow events.

  17. The perfect debris flow? Aggregated results from 28 large-scale experiments

    USGS Publications Warehouse

    Iverson, Richard M.; Logan, Matthew; LaHusen, Richard G.; Berti, Matteo

    2010-01-01

    Aggregation of data collected in 28 controlled experiments reveals reproducible debris-flow behavior that provides a clear target for model tests. In each experiment ∼10 m3 of unsorted, water-saturated sediment composed mostly of sand and gravel discharged from behind a gate, descended a steep, 95-m flume, and formed a deposit on a nearly horizontal runout surface. Experiment subsets were distinguished by differing basal boundary conditions (1 versus 16 mm roughness heights) and sediment mud contents (1 versus 7 percent dry weight). Sensor measurements of evolving flow thicknesses, basal normal stresses, and basal pore fluid pressures demonstrate that debris flows in all subsets developed dilated, coarse-grained, high-friction snouts, followed by bodies of nearly liquefied, finer-grained debris. Mud enhanced flow mobility by maintaining high pore pressures in flow bodies, and bed roughness reduced flow speeds but not distances of flow runout. Roughness had these effects because it promoted debris agitation and grain-size segregation, and thereby aided growth of lateral levees that channelized flow. Grain-size segregation also contributed to development of ubiquitous roll waves, which had diverse amplitudes exhibiting fractal number-size distributions. Despite the influence of these waves and other sources of dispersion, the aggregated data have well-defined patterns that help constrain individual terms in a depth-averaged debris-flow model. The patterns imply that local flow resistance evolved together with global flow dynamics, contradicting the hypothesis that any consistent rheology applied. We infer that new evolution equations, not new rheologies, are needed to explain how characteristic debris-flow behavior emerges from the interactions of debris constituents.

  18. The effect of moisture content on solid-state anaerobic digestion of dairy manure from a sawdust-bedded pack barn

    USDA-ARS?s Scientific Manuscript database

    The effect of moisture content on solid-state anaerobic digestion of dairy manure from a Korean sawdust-bedded pack barn was determined using laboratory-scale digesters operated at three moisture levels (70, 76, and 83% on a wet basis) at 37 C for 85 days. Results showed that digesters containing m...

  19. Debris Flow Process and Climate Controls on Steepland Valley Form and Evolution

    NASA Astrophysics Data System (ADS)

    Struble, W.; Roering, J. J.

    2017-12-01

    In unglaciated mountain ranges, steepland bedrock valleys often dominate relief structure and dictate landscape response to perturbations in tectonics or climate; drainage divides have been shown to be dynamic and drainage capture is common. Landscape evolution models often use the stream power model to simulate morphologic changes, but steepland valley networks exhibit trends that deviate from predictions of this model. The prevalence of debris flows in steep channels has motivated approaches that account for commonly observed curvature of slope-area data at small drainage areas. Debris flow deposits correspond with observed curvature in slope-area data, wherein slope increases slowly as drainage area decreases; debris flow incision is implied upstream of deposits. In addition, shallow landslides and in-channel sediment entrainment in humid and arid regions, respectively, have been identified as likely debris flow triggering mechanisms, but the extent to which they set the slope of steep channels is unclear. While an untested model exists for humid landscape debris flows, field observations and models are lacking for regions with lower mean annual precipitation. The Oregon Coastal Ranges are an ideal humid setting for observing how shallow landslide-initiated debris flows abrade channel beds and/or drive exposure-driven weathering. Preliminary field observations in the Lost River Range and the eastern Sierra Nevada - semi-arid and unglaciated environments - suggest that debris flows are pervasive in steep reaches. Evidence for fluvial incision is lacking and the presence of downstream debris flow deposits and a curved morphologic signature in slope-area space suggests stream power models are insufficient for predicting and interpreting landscape dynamics. Investigation of debris flow processes in both humid and arid sites such as these seeks to identify the linkage between sediment transport and the characteristic form of steepland valleys. Bedrock weathering

  20. Enhancing the Scientific Return from HST Imaging of Debris Disks

    NASA Astrophysics Data System (ADS)

    Weinberger, Alycia

    2016-10-01

    We propose realistic modeling of scattering of light by small aggregate dust grains that will enable us to interpret visible to near-infrared imaging of debris disks. We will determine if disk colors, phase functions, and polarizations place unique constraints on the composition of debris dust. Ongoing collisions of planetesimals generate dust; therefore, the dust provides unique information on compositions of the parent bodies. These exosolar analogs of asteroids and comets can bear clues to the history of a planetary system including migration and thermal processing. Because directly imaged debris disks are cold, they have no solid state emission features. Grain scattering properties as a function of wavelength are our only tool to reveal their compositions. Solar system interplanetary dust particles are fluffy aggregates, but most previous work on debris disk composition relied on Mie theory, i.e. assumed compact spherical grains. Mie calculations do not reproduce the observed colors and phase functions observed from debris disks. The few more complex calculations that exist do not explore the range of compositions and sizes relevant to debris disk dust. In particular, we expect porosity to help distinguish between cometary-like parent bodies, which are fluffy due to high volatile content and low collisional velocities, and asteroidal-like parent bodies that are compacted.

  1. Material Density Distribution of Small Debris in Earth Orbit

    NASA Technical Reports Server (NTRS)

    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 (< 2 g/cc), medium density (2 to 6 g/cc), and high 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

  2. Bacterial counts on teat skin and in new sand, recycled sand, and recycled manure solids used as bedding in freestalls.

    PubMed

    Rowbotham, R F; Ruegg, P L

    2016-08-01

    On modern dairy farms, environmental mastitis pathogens are usually the predominant cause of mastitis, and bedding often serves as a point of exposure to these organisms. The objective of this longitudinal study was to determine bacterial populations of 4 different bedding types [deep-bedded new sand (NES), deep-bedded recycled sand (RS), deep-bedded manure solids (DBMS), and shallow-bedded manure solids over foam core mattresses (SBMS)] and of teat skin swabs of primarily primiparous cows housed in a single facility over all 4 seasons. Samples of bedding were collected weekly (n=49wk) from pens that each contained 32 lactating dairy cows. Throughout the length of the same period, composite swabs of teat skin were collected weekly from all cows before and after premilking teat sanitation. Median numbers of streptococci and streptococci-like organisms (SSLO) were >8.6×10(6) cfu/g and >6.9×10(3) cfu/teat swab for all bedding types and teat swabs, respectively. Numbers of SSLO were greatest in samples of SBMS (2.1×10(8) cfu/g) and least in samples of NES (8.6×10(6) cfu/g), RS (1.3×10(7) cfu/g), and DBMS (1.7×10(7) cfu/g). Numbers of gram-negative bacteria in bedding (5.5×10(4) to 1.2×10(7) cfu/g) were fewer than numbers of SSLO (8.6×10(6) to 2.1×10(8) cfu/g). Numbers of coliform bacteria were greatest in samples of DBMS (2.2×10(6) cfu/g) and least in samples of NES (3.6×10(3) cfu/g). In general, the relative number of bacteria on teat skin corresponded to exposure in bedding. Numbers of gram-negative bacteria recovered from prepreparation teat swabs were greatest for cows bedded with DBMS (1.0×10(4) cfu/swab) and RS (2.5×10(3) cfu/swab) and least for cows bedded with NES (5.8×10(2) cfu/swab). Median numbers of coliform and Klebsiella spp. recovered from prepreparation teat swabs were below the limit of detection for all cows except those bedded with DBMS. Numbers of SSLO recovered from prepreparation teat swabs were least for cows bedded with DBMS (6.9

  3. Effects of composition of grains of debris flow on its impact force

    NASA Astrophysics Data System (ADS)

    Tang, jinbo; Hu, Kaiheng; Cui, Peng

    2017-04-01

    Debris flows compose of solid material with broad size distribution from fine sand to boulders. Impact force imposed by debris flows is a very important issue for protection engineering design and strongly influenced by their grain composition. However, this issue has not been studied in depth and the effects of grain composition not been considered in the calculation of the impact force. In this present study, the small-scale flume experiments with five kinds of compositions of grains for debris flow were carried out to study the effect of the composition of grains of debris flow on its impact force. The results show that the impact force of debris flow increases with the grain size, the hydrodynamic pressure of debris flow is calibrated based on the normalization parameter dmax/d50, in which dmax is the maximum size and d50 is the median size. Furthermore, a log-logistic statistic distribution could be used to describe the distribution of magnitude of impact force of debris flow, where the mean and the variance of the present distribution increase with grain size. This distribution proposed in the present study could be used to the reliability analysis of structures impacted by debris flow.

  4. Characterization of Hypervelocity Impact Debris from the DebriSat Tests

    NASA Astrophysics Data System (ADS)

    Adams, P. M.; Sheaffer, P. M.; Lingley, Z.; Radhakrishnan, G.

    The DebriSat program consisted of 3 hypervelocity impact tests conducted in 2 Torr of air with 7 km/s, 600 g aluminum projectiles. In the first test, Pre Preshot, the target consisted of multiple layers of fiberglass, stainless steel and Kevlar fabric. No soft catch foam was used. The subsequent two tests, DebrisLV and DebriSat, were designed to simulate hypervelocity impacts with a launch vehicle upper stage and a modern LEO satellite, respectively. The interior of the chamber was lined with soft catch foam to trap break-up fragments. In all three tests, witness plates were placed near the target to sample impact debris and determine its reflectance, composition and spectral properties. Reflectance measurements are important for calculating the size of orbital hypervelocity impact fragments. The debris from the Pre Preshot test consisted of a two-phase mixture formed from solidified molten silicate and steel droplets. Individual droplets ranged from 100 μm to 10 nm. The reflectance of witness plates dropped from 95% to 20-30% as a result of the debris. Debris collected on witness plates in the DebrisLV and DebriSat tests consisted of μm to nm-sized solidified molten metallic droplets in a matrix of condensed vaporized soft catch. Disordered graphitic carbon was also detected. The reflectance of debris-covered witness plates dropped from 95% to 5%. The dramatic decrease in reflectance for hypervelocity impact debris is attributed to the effect of scattering from μm to nm sized solidified molten metallic droplets and the presence of graphitic carbon, when organics are present. The presence of soft catch in the later tests and the high organic content with graphitic carbon in the debris appear to be responsible for this much lower post-test reflectance. Understanding orbital debris reflectance is critical for estimating size and determining debris detectability.

  5. Fluidized-bed catalytic coal-gasification process. [US patent; pretreatment to minimize agglomeration

    DOEpatents

    Euker, C.A. Jr.; Wesselhoft, R.D.; Dunkleman, J.J.; Aquino, D.C.; Gouker, T.R.

    1981-09-14

    Coal or similar carbonaceous solids impregnated with gasification catalyst constituents are oxidized by contact with a gas containing between 2 vol % and 21 vol % oxygen at a temperature between 50 and 250/sup 0/C in an oxidation zone and the resultant oxidized, catalyst impregnated solids are then gasified in a fluidized bed gasification zone at an elevated pressure. The oxidation of the catalyst impregnated solids under these conditions insures that the bed density in the fluidized bed gasification zone will be relatively high even though the solids are gasified at elevated pressure and temperature.

  6. Apparatus and process for controlling fluidized beds

    DOEpatents

    Rehmat, Amirali G.; Patel, Jitendra G.

    1985-10-01

    An apparatus and process for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance.

  7. Summary of Blast Shield and Material Testing for Development of Solid Debris Collection at the National Ignition Facility (NIF)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shaughnessy, D A; Gostic, J M; Moody, K J

    2011-11-21

    The ability to collect solid debris from the target chamber following a NIF shot has application for both capsule diagnostics, particularly for fuel-ablator mix, and measuring cross sections relevant to the Stockpile Stewardship program and nuclear astrophysics. Simulations have shown that doping the capsule with up to 10{sup 15} atoms of an impurity not otherwise found in the capsule does not affect its performance. The dopant is an element that will undergo nuclear activations during the NIF implosion, forming radioactive species that can be collected and measured after extraction from the target chamber. For diagnostics, deuteron or alpha induced reactionsmore » can be used to probe the fuel-ablator mix. For measuring neutron cross sections, the dopant should be something that is sensitive to the 14 MeV neutrons produced through the fusion of deuterium and tritium. Developing the collector is a challenge due to the extreme environment of the NIF chamber. The collector surface is exposed to a large photon flux from x-rays and unconverted laser light before it is exposed to a debris wind that is formed from vaporized material from the target chamber center. The photons will ablate the collector surface to some extent, possibly impeding the debris from reaching the collector and sticking. In addition, the collector itself must be mechanically strong enough to withstand the large amount of energy it will be exposed to, and it should be something that will be easy to count and chemically process. In order to select the best material for the collector, a variety of different metals have been tested in the NIF chamber. They were exposed to high-energy laser shots in order to evaluate their postshot surface characterization, morphology, degree of melt, and their ability to retain debris from the chamber center. The first set of samples consisted of 1 mm thick pieces of aluminum that had been fielded in the chamber as blast shields protecting the neutron activation

  8. HVI-Test Setup for Debris Detector Verification

    NASA Astrophysics Data System (ADS)

    Bauer, Waldemar; Romberg, Oliver; Wiedemann, Carsten; Putzar, Robin; Drolshagen, Gerhard; Vorsmann, Peter

    2013-08-01

    Risk assessment concerning impacting space debris or micrometeoroids with spacecraft or payloads can be performed by using environmental models such as MASTER (ESA) or ORDEM (NASA). The validation of such models is performed by comparison of simulated results with measured data. Such data can be obtained from ground-based or space-based radars or telescopes, or by analysis of space hardware (e.g. Hubble Space Telescope, Space Shuttle Windows), which are retrieved from orbit. An additional data source is in-situ impact detectors, which are purposed for the collection of space debris and micrometeoroids impact data. In comparison to the impact data gained by analysis of the retrieved surfaces, the detected data contains additional information regarding impact time and orbit. In the past, many such in-situ detectors have been developed, with different measurement methods for the identification and classification of impacting objects. However, existing detectors have a drawback in terms of data acquisition. Generally the detection area is small, limiting the collected data as the number of recorded impacts has a linear dependence to the exposed area. An innovative impact detector concept is currently under development at the German Aerospace Centre (DLR) in Bremen, in order to increase the surface area while preserving the advantages offered by dedicated in-situ impact detectors. The Solar Generator based Impact Detector (SOLID) is not an add-on component on the spacecraft, making it different to all previous impact detectors. SOLID utilises existing subsystems of the spacecraft and adapts them for impact detection purposes. Solar generators require large panel surfaces in order to provide the spacecraft with sufficient energy. Therefore, the spacecraft solar panels provide a perfect opportunity for application as impact detectors. Employment of the SOLID method in several spacecraft in various orbits would serve to significantly increase the spatial coverage

  9. Variations in debris distribution and thickness on Himalayan debris-covered glaciers

    NASA Astrophysics Data System (ADS)

    Gibson, Morgan; Rowan, Ann; Irvine-Fynn, Tristram; Quincey, Duncan; Glasser, Neil

    2016-04-01

    Many Himalayan glaciers are characterised by extensive supraglacial debris coverage; in Nepal 33% of glaciers exhibit a continuous layer of debris covering their ablation areas. The presence of such a debris layer modulates a glacier's response to climatic change. However, the impact of this modulation is poorly constrained due to inadequate quantification of the impact of supraglacial debris on glacier surface energy balance. Few data exist to describe spatial and temporal variations in parameters such as debris thickness, albedo and surface roughness in energy balance calculations. Consequently, improved understanding of how debris affects Himalayan glacier ablation requires the assessment of surface energy balance model sensitivity to spatial and temporal variability in these parameters. Measurements of debris thickness, surface temperature, reflectance and roughness were collected across Khumbu Glacier during the pre- and post-monsoon seasons of 2014 and 2015. The extent of the spatial variation in each of these parameters are currently being incorporated into a point-based glacier surface energy balance model (CMB-RES, Collier et al., 2014, The Cryosphere), applied on a pixel-by-pixel basis to the glacier surface, to ascertain the sensitivity of glacier surface energy balance and ablation values to these debris parameters. A time series of debris thickness maps have been produced for Khumbu Glacier over a 15-year period (2000-2015) using Mihalcea et al.'s (2008, Cold Reg. Sci. Technol.) method, which utilised multi-temporal ASTER thermal imagery and our in situ debris surface temperature and thickness measurements. Change detection between these maps allowed the identification of variations in debris thickness that could be compared to discrete measurements, glacier surface velocity and morphology of the debris-covered area. Debris thickness was found to vary spatially between 0.1 and 4 metres within each debris thickness map, and temporally on the order of 1

  10. Effects of episodic sediment supply on bedload transport rate in mountain rivers. Detecting debris flow activity using continuous monitoring

    NASA Astrophysics Data System (ADS)

    Uchida, Taro; Sakurai, Wataru; Iuchi, Takuma; Izumiyama, Hiroaki; Borgatti, Lisa; Marcato, Gianluca; Pasuto, Alessandro

    2018-04-01

    Monitoring of sediment transport from hillslopes to channel networks as a consequence of floods with suspended and bedload transport, hyperconcentrated flows, debris and mud flows is essential not only for scientific issues, but also for prevention and mitigation of natural disasters, i.e. for hazard assessment, land use planning and design of torrent control interventions. In steep, potentially unstable terrains, ground-based continuous monitoring of hillslope and hydrological processes is still highly localized and expensive, especially in terms of manpower. In recent years, new seismic and acoustic methods have been developed for continuous bedload monitoring in mountain rivers. Since downstream bedload transport rate is controlled by upstream sediment supply from tributary channels and bed-external sources, continuous bedload monitoring might be an effective tool for detecting the sediments mobilized by debris flow processes in the upper catchment and thus represent an indirect method to monitor slope instability processes at the catchment scale. However, there is poor information about the effects of episodic sediment supply from upstream bed-external sources on downstream bedload transport rate at a single flood time scale. We have examined the effects of sediment supply due to upstream debris flow events on downstream bedload transport rate along the Yotagiri River, central Japan. To do this, we have conducted continuous bedload observations using a hydrophone (Japanese pipe microphone) located 6.4 km downstream the lower end of a tributary affected by debris flows. Two debris flows occurred during the two-years-long observation period. As expected, bedload transport rate for a given flow depth showed to be larger after storms triggering debris flows. That is, although the magnitude of sediment supply from debris flows is not large, their effect on bedload is propagating >6 km downstream at a single flood time scale. This indicates that continuous bedload

  11. Dynamic interaction of two-phase debris flow with pyramidal defense structures: An optimal strategy to efficiently protecting the desired area

    NASA Astrophysics Data System (ADS)

    Kattel, Parameshwari; Kafle, Jeevan; Fischer, Jan-Thomas; Mergili, Martin; Tuladhar, Bhadra Man; Pudasaini, Shiva P.

    2017-04-01

    In this work we analyze the dynamic interaction of two phase debris flows with pyramidal obstacles. To simulate the dynamic interaction of two-phase debris flow (a mixture of solid particles and viscous fluid) with obstacles of different dimensions and orientations, we employ the general two-phase mass flow model (Pudasaini, 2012). The model consists of highly non-linear partial differential equations representing the mass and momentum conservations for both solid and fluid. Besides buoyancy, the model includes some dominant physical aspects of the debris flows such as generalized drag, virtual mass and non-Newtonian viscous stress as induced by the gradient of solid-volume-fraction. Simulations are performed with high-resolution numerical schemes to capture essential dynamics, including the strongly re-directed flow with multiple stream lines, mass arrest and debris-vacuum generation when the rapidly cascading debris mass suddenly encounters the obstacle. The solid and fluid phases show fundamentally different interactions with obstacles, flow spreading and dispersions, run-out dynamics, and deposition morphology. A forward-facing pyramid deflects the mass wider, and a rearward-facing pyramid arrests a portion of solid-mass at its front. Our basic study reveals that appropriately installed obstacles, their dimensions and orientations have a significant influence on the flow dynamics, material redistribution and redirection. The precise knowledge of the change in dynamics is of great importance for the optimal and effective protection of designated areas along the mountain slopes and the runout zones. Further important results are, that specific installations lead to redirect either solid, or fluid, or both, in the desired amounts and directions. The present method of the complex interactions of real two-phase mass flows with the obstacles may help us to construct defense structures and to design advanced and physics-based engineering solutions for the prevention

  12. Dynamic Modeling and Control Studies of a Two-Stage Bubbling Fluidized Bed Adsorber-Reactor for Solid-Sorbent CO{sub 2} Capture

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Modekurti, Srinivasarao; Bhattacharyya, Debangsu; Zitney, Stephen E.

    2013-07-31

    A one-dimensional, non-isothermal, pressure-driven dynamic model has been developed for a two-stage bubbling fluidized bed (BFB) adsorber-reactor for solid-sorbent carbon dioxide (CO{sub 2}) capture using Aspen Custom Modeler® (ACM). The BFB model for the flow of gas through a continuous phase of downward moving solids considers three regions: emulsion, bubble, and cloud-wake. Both the upper and lower reactor stages are of overflow-type configuration, i.e., the solids leave from the top of each stage. In addition, dynamic models have been developed for the downcomer that transfers solids between the stages and the exit hopper that removes solids from the bottom ofmore » the bed. The models of all auxiliary equipment such as valves and gas distributor have been integrated with the main model of the two-stage adsorber reactor. Using the developed dynamic model, the transient responses of various process variables such as CO{sub 2} capture rate and flue gas outlet temperatures have been studied by simulating typical disturbances such as change in the temperature, flowrate, and composition of the incoming flue gas from pulverized coal-fired power plants. In control studies, the performance of a proportional-integral-derivative (PID) controller, feedback-augmented feedforward controller, and linear model predictive controller (LMPC) are evaluated for maintaining the overall CO{sub 2} capture rate at a desired level in the face of typical disturbances.« less

  13. Treatability Variance for Containerised Liquids in Mixed Debris Waste - 12101

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Alstatt, Catherine M.

    2012-07-01

    The TRU Waste Processing Center (TWPC) is a Department of Energy facility whose mission is to receive and process for appropriate disposal legacy Contact Handled (CH) and Remote Handled (RH) waste, including debris waste stored at various DOE Oak Ridge facilities. Acceptable Knowledge (AK) prepared for the waste characterizes the waste as mixed waste, meaning it is both radioactive and regulated under the Resource Conservation and Recovery Act (RCRA). The AK also indicates that a number of the debris waste packages contain small amounts of containerised liquids. The documentation indicates liquid wastes generated in routine lab operations were typically collectedmore » for potential recovery of valuable isotopes. However, during activities associated with decontamination and decommissioning (D and D), some containers with small amounts of liquids were placed into the waste containers with debris waste. Many of these containers now hold from 2.5 milliliters (ml) to 237 ml of liquid; a few contain larger volumes. At least some of these containers were likely empty at the time of generation, but documentation of this condition is lacking. Since WIPP compliant AK is developed on a waste stream basis, rather than an individual container basis, and includes every potential RCRA hazardous constituent within the waste stream, it is insufficient for the purpose of characterizing individual containers of liquid. Debris waste is defined in 40 CFR 268.2(g) as 'solid material exceeding a 60 mm particle size that is intended for disposal and that is: a manufactured object; or plant or animal matter; or natural geologic material'. The definition further states that intact containers of hazardous waste that are not ruptured and that retain at least 75% of their original volume are not debris. The prescribed treatment is removal of intact containers from the debris waste, and treatment of their contents to meet specific Land Disposal Restrictions (LDR) standards. This is true for

  14. Active space debris removal by a hybrid propulsion module

    NASA Astrophysics Data System (ADS)

    DeLuca, L. T.; Bernelli, F.; Maggi, F.; Tadini, P.; Pardini, C.; Anselmo, L.; Grassi, M.; Pavarin, D.; Francesconi, A.; Branz, F.; Chiesa, S.; Viola, N.; Bonnal, C.; Trushlyakov, V.; Belokonov, I.

    2013-10-01

    During the last 40 years, the mass of the artificial objects in orbit increased quite steadily at the rate of about 145 metric tons annually, leading to a total tally of approximately 7000 metric tons. Now, most of the cross-sectional area and mass (97% in LEO) is concentrated in about 4600 intact objects, i.e. abandoned spacecraft and rocket bodies, plus a further 1000 operational spacecraft. Simulations and parametric analyses have shown that the most efficient and effective way to prevent the outbreak of a long-term exponential growth of the catalogued debris population would be to remove enough cross-sectional area and mass from densely populated orbits. In practice, according to the most recent NASA results, the active yearly removal of approximately 0.1% of the abandoned intact objects would be sufficient to stabilize the catalogued debris in low Earth orbit, together with the worldwide adoption of mitigation measures. The candidate targets for removal would have typical masses between 500 and 1000 kg, in the case of spacecraft, and of more than 1000 kg, in the case of rocket upper stages. Current data suggest that optimal active debris removal missions should be carried out in a few critical altitude-inclination bands. This paper deals with the feasibility study of a mission in which the debris is removed by using a hybrid propulsion module as propulsion unit. Specifically, the engine is transferred from a servicing platform to the debris target by a robotic arm so to perform a controlled disposal. Hybrid rocket technology for de-orbiting applications is considered a valuable option due to high specific impulse, intrinsic safety, thrust throttle ability, low environmental impact and reduced operating costs. Typically, in hybrid rockets a gaseous or liquid oxidizer is injected into the combustion chamber along the axial direction to burn a solid fuel. However, the use of tangential injection on a solid grain Pancake Geometry allows for more compact design of

  15. Fluidized bed regenerators for Brayton cycles

    NASA Technical Reports Server (NTRS)

    Nichols, L. D.

    1975-01-01

    A recuperator consisting of two fluidized bed regenerators with circulating solid particles is considered for use in a Brayton cycle. These fluidized beds offer the possibility of high temperature operation if ceramic particles are used. Calculations of the efficiency and size of fluidized bed regenerators for typical values of operating parameters were made and compared to a shell and tube recuperator. The calculations indicate that the fluidized beds will be more compact than the shell and tube as well as offering a high temperature operating capability.

  16. Tracing the contribution of debris flow-dominated channels to gravel-bed torrential river channel: implementing pit-tags in the upper Guil River (French Alps)

    NASA Astrophysics Data System (ADS)

    Arnaud-Fassetta, Gilles; Lissak, Candide; Fort, Monique; Bétard, François; Carlier, Benoit; Cossart, Etienne; Madelin, Malika; Viel, Vincent; Charnay, Bérengère; Bletterie, Xavier

    2014-05-01

    In the upper, wider reaches of Alpine valleys, shaping of active channels is usually subject to rapid change. It mostly depends upon hydro-climatic variability, runoff concentration and sediment supply, and may result in alternating sequences of fluvial and debris-flow pulses, as recorded in alluvial fans and terraces. Our study, carried in the frame of SAMCO (ANR) project, focuses on the upper Guil River Valley (Queyras, Southern French Alps) cut into the slaty shale "schistes lustrés". Steep, lower order drains carry a contrasted solid discharge, including predominantly sandy-loam particles mixed with gravels and boulders (sandstone schists, ophiolites). Abundant sediment supply by frost shattering, snow avalanche and landslides is then reworked during snowmelt or summer storm runoff events, and may result in catastrophic, very destructive floods along the main channel, as shown by historical records. Following the RI-30 year 2000 flood, our investigations included sediment budgets, i.e. balance of erosion and deposition, and the mapping of the source, transport and storage of various sediments (talus, colluvium, torrential fans, terraces). To better assess sediment fluxes and sediment delivery into the main channel network, we implemented tracers (pit-tags) in selected sub-catchments, significantly contributing to the sediment yield of the valley bottoms during the floods and/or avalanches: Maloqueste, Combe Morel, Bouchouse and Peyronnelle catchments. The first three are direct tributaries of the Guil River whereas the Peyronnelle is a left bank tributary of the Peynin River, which joins the Guil River via an alluvial cone with high human and material stakes. The Maloqueste and the Combe Morel are two tributaries facing each other in the Guil valley, representing a double lateral constraint for the road during flood events of the Guil River. After pit-tag initialisation in laboratory, we set them up along the four tributaries: Maloqueste (20 pit-tags), Combe

  17. Coarse-grained discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers [Discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers

    DOE PAGES

    Verma, Vikrant; Li, Tingwen; De Wilde, Juray

    2017-05-26

    Vortex chambers allow the generation of rotating fluidized beds, offering high-G intensified gas-solid contact, gas-solids separation and solids-solids segregation. Focusing on binary particle mixtures and fixing the density and diameter of the heavy/large particles, transient batch CFD-coarse-grained DPM simulations were carried out with varying densities or sizes of the light/small particles to evaluate to what extent combining these three functionalities is possible within a vortex chamber of given design. Both the rate and quality of segregation were analyzed. Within a relatively wide density and size range, fast and efficient segregation takes place, with an inner and slower rotating bed ofmore » the lighter/small particles forming within the outer and faster rotating bed of the heavier/large particles. Simulations show that the contamination of the outer bed with lighter particles occurs more easily than contamination of the inner bed with heavier particles and increases with decreasing difference in size or density of the particles. Bubbling in the inner bed is observed with an inner bed of very low density or small particles. Porosity plots show that vortex chambers with a sufficient number of gas inlet slots have to be used to guarantee a uniform gas distribution and particle bed. Lastly, the flexibility of particle segregation in vortex chambers with respect to the gas flow rate is demonstrated.« less

  18. Coarse-grained discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers [Discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Verma, Vikrant; Li, Tingwen; De Wilde, Juray

    Vortex chambers allow the generation of rotating fluidized beds, offering high-G intensified gas-solid contact, gas-solids separation and solids-solids segregation. Focusing on binary particle mixtures and fixing the density and diameter of the heavy/large particles, transient batch CFD-coarse-grained DPM simulations were carried out with varying densities or sizes of the light/small particles to evaluate to what extent combining these three functionalities is possible within a vortex chamber of given design. Both the rate and quality of segregation were analyzed. Within a relatively wide density and size range, fast and efficient segregation takes place, with an inner and slower rotating bed ofmore » the lighter/small particles forming within the outer and faster rotating bed of the heavier/large particles. Simulations show that the contamination of the outer bed with lighter particles occurs more easily than contamination of the inner bed with heavier particles and increases with decreasing difference in size or density of the particles. Bubbling in the inner bed is observed with an inner bed of very low density or small particles. Porosity plots show that vortex chambers with a sufficient number of gas inlet slots have to be used to guarantee a uniform gas distribution and particle bed. Lastly, the flexibility of particle segregation in vortex chambers with respect to the gas flow rate is demonstrated.« less

  19. Projectile Shape Effects Analysis for Space Debris Impact

    NASA Astrophysics Data System (ADS)

    Shiraki, Kuniaki; Yamamoto, Tetsuya; Kamiya, Takeshi

    2002-01-01

    (JEM IST), has a manned pressurized module used as a research laboratory on orbit and planned to be attached to the International Space Station (ISS). Protection system from Micrometeoroids and orbital debris (MM/OD) is very important for crew safety aboard the ISS. We have to design a module with shields attached to the outside of the pressurized wall so that JEM can be protected when debris of diameter less than 20mm impact on the JEM wall. In this case, the ISS design requirement for space debris protection system is specified as the Probability of No Penetration (PNP). The PNP allocation for the JEM is 0.9738 for ten years, which is reallocated as 0.9814 for the Pressurized Module (PM) and 0.9922 for the Experiment Logistics Module-Pressurized Section (ELM-PS). The PNP is calculated with Bumper code provided by NASA with the following data inputs to the calculation. (1) JEM structural model (2) Ballistic Limit Curve (BLC) of shields pressure wall (3) Environmental conditions: Analysis type, debris distribution, debris model, debris density, Solar single aluminum plate bumper (1.27mm thickness). The other is a Stuffed Whipple shield with its second bumper composed of an aluminum mesh, three layers of Nextel AF62 ceramic fabric, and four layers of Kevlar 710 fabric with thermal isolation material Multilayer Insulation (MLI) in the bottom. The second bumper of Stuffed Whipple shields is located at the middle between the first bumper and the 4.8 mm-thick pressurized wall. with Two-Stage Light Gas Gun (TSLGG) tests and hydro code simulation already. The remaining subject is the verification of JEM debris protection shields for velocities ranging from 7 to 15 km/sec. We conducted Conical Shaped Charge (CSC) tests that enable hypervelocity impact tests for the debris velocity range above 10 km/sec as well as hydro code simulation. because of the jet generation mechanism. It is therefore necessary to analyze and compensate the results for a solid aluminum sphere, which

  20. Application of process tomography in gas-solid fluidised beds in different scales and structures

    NASA Astrophysics Data System (ADS)

    Wang, H. G.; Che, H. Q.; Ye, J. M.; Tu, Q. Y.; Wu, Z. P.; Yang, W. Q.; Ocone, R.

    2018-04-01

    Gas-solid fluidised beds are commonly used in particle-related processes, e.g. for coal combustion and gasification in the power industry, and the coating and granulation process in the pharmaceutical industry. Because the operation efficiency depends on the gas-solid flow characteristics, it is necessary to investigate the flow behaviour. This paper is about the application of process tomography, including electrical capacitance tomography (ECT) and microwave tomography (MWT), in multi-scale gas-solid fluidisation processes in the pharmaceutical and power industries. This is the first time that both ECT and MWT have been applied for this purpose in multi-scale and complex structure. To evaluate the sensor design and image reconstruction and to investigate the effects of sensor structure and dimension on the image quality, a normalised sensitivity coefficient is introduced. In the meantime, computational fluid dynamic (CFD) analysis based on a computational particle fluid dynamic (CPFD) model and a two-phase fluid model (TFM) is used. Part of the CPFD-TFM simulation results are compared and validated by experimental results from ECT and/or MWT. By both simulation and experiment, the complex flow hydrodynamic behaviour in different scales is analysed. Time-series capacitance data are analysed both in time and frequency domains to reveal the flow characteristics.

  1. Wildfire impacts on the processes that generate debris flows in burned watersheds

    USGS Publications Warehouse

    Parise, M.; Cannon, S.H.

    2012-01-01

    Every year, and in many countries worldwide, wildfires cause significant damage and economic losses due to both the direct effects of the fires and the subsequent accelerated runoff, erosion, and debris flow. Wildfires can have profound effects on the hydrologic response of watersheds by changing the infiltration characteristics and erodibility of the soil, which leads to decreased rainfall infiltration, significantly increased overland flow and runoff in channels, and movement of soil. Debris-flow activity is among the most destructive consequences of these changes, often causing extensive damage to human infrastructure. Data from the Mediterranean area and Western United States of America help identify the primary processes that result in debris flows in recently burned areas. Two primary processes for the initiation of fire-related debris flows have been so far identified: (1) runoff-dominated erosion by surface overland flow; and (2) infiltration-triggered failure and mobilization of a discrete landslide mass. The first process is frequently documented immediately post-fire and leads to the generation of debris flows through progressive bulking of storm runoff with sediment eroded from the hillslopes and channels. As sediment is incorporated into water, runoff can convert to debris flow. The conversion to debris flow may be observed at a position within a drainage network that appears to be controlled by threshold values of upslope contributing area and its gradient. At these locations, sufficient eroded material has been incorporated, relative to the volume of contributing surface runoff, to generate debris flows. Debris flows have also been generated from burned basins in response to increased runoff by water cascading over a steep, bedrock cliff, and incorporating material from readily erodible colluvium or channel bed. Post-fire debris flows have also been generated by infiltration-triggered landslide failures which then mobilize into debris flows. However

  2. Predicting debris

    NASA Technical Reports Server (NTRS)

    Kessler, Donald J.

    1988-01-01

    The probable amount, sizes, and relative velocities of debris are discussed, giving examples of the damage caused by debris, and focusing on the use of mathematical models to forecast the debris environment and solar activity now and in the future. Most debris are within 2,000 km of the earth's surface. The average velocity of spacecraft-debris collisions varies from 9 km/sec at 30 degrees of inclination to 13 km/sec near polar orbits. Mathematical models predict a 5 percent per year increase in the large-fragment population, producing a small-fragment population increase of 10 percent per year until the year 2060, the time of critical density. A 10 percent increase in the large population would cause the critical density to be reached around 2025.

  3. Mathematical modeling as a tool to investigate the design and operation of the zymotis packed-bed bioreactor for solid-state fermentation.

    PubMed

    Mitchell, D A; von Meien, O F

    2000-04-20

    Zymotis bioreactors for solid-state fermentation (SSF) are packed-bed bioreactors with internal cooling plates. This design has potential to overcome the problem of heat removal, which is one of the main challenges in SSF. In ordinary packed-bed bioreactors, which lack internal plates, large axial temperature gradients arise, leading to poor microbial growth in the end of the bed near the air outlet. The Zymotis design is suitable for SSF processes in which the substrate bed must be maintained static, but little is known about how to design and operate Zymotis bioreactors. We use a two-dimensional heat transfer model, describing the growth of Aspergillus niger on a starchy substrate, to provide guidelines for the optimum design and operation of Zymotis bioreactors. As for ordinary packed-beds, the superficial velocity of the process air is a key variable. However, the Zymotis design introduces other important variables, namely, the spacing between the internal cooling plates and the temperature of the cooling water. High productivities can be achieved at large scale, but only if small spacings between the cooling plates are used, and if the cooling water temperature is varied during the fermentation in response to bed temperatures. Copyright 2000 John Wiley & Sons, Inc.

  4. Solid-state Fermentation of Xylanase from Penicillium canescens 10-10c in a Multi-layer-packed Bed Reactor

    NASA Astrophysics Data System (ADS)

    Assamoi, Antoine A.; Destain, Jacqueline; Delvigne, Frank; Lognay, Georges; Thonart, Philippe

    Xylanase is produced by Penicillium canescens 10-10c from soya oil cake in static conditions using solid-state fermentation. The impact of several parameters such as the nature and the size of inoculum, bed-loading, and aeration is evaluated during the fermentation process. Mycelial inoculum gives more production than conidial inoculum. Increasing the quantity of inoculum enhances slightly xylanase production. Forced aeration induces more sporulation of strain and reduces xylanase production. However, forced moistened air improves the production compared to production obtained with forced dry air. In addition, increasing bed-loading reduces the specific xylanase production likely due to the incapacity of the Penicillium strain to grow deeply in the fermented soya oil cake mass. Thus, the best cultivation conditions involve mycelial inoculum form, a bed loading of 1-cm height and passive aeration. The maximum xylanase activity is obtained after 7 days of fermentation and attains 10,200 U/g of soya oil cake. These levels are higher than those presented in the literature and, therefore, show all the potentialities of this stock and this technique for the production of xylanase.

  5. Experimental modelling of outburst flood - bed interactions

    NASA Astrophysics Data System (ADS)

    Carrivick, J. L.; Xie, Z.; Sleigh, A.; Hubbard, M.

    2009-04-01

    Outburst floods are a sudden release and advancing wave of water and sediment, with a peak discharge that is often several orders of magnitude greater than perennial flows. Common outburst floods from natural sources include those from glacial and moraine-impounded lakes, freshwater dyke and levee bursts, volcanic debris dams, landslides, avalanches, coastal bay-bars, and those from tree or vegetation dams. Outburst flood hazards are regularly incorporated into risk assessments for urban, coastal and mountainous areas, for example. Outburst flood hazards are primarily due to direct impacts, caused by a frontal surge wave, from debris within a flow body, and from the mass and consistency of the flows. A number of secondary impacts also pose hazards, including widespread deposition of sediment and blocked tributary streams. It is rapid landscape change, which is achieved the mobilization and redistribution of sediment that causes one of the greatest hazards due to outburst floods. The aim of this project is therefore to parameterise hydrodynamic - sedimentary interactions in experimental outburst floods. Specifically, this project applies laboratory flume modelling, which offers a hitherto untapped opportunity for examining complex interactions between water and sediment within outburst floods. The experimental set-up is of a tradition lock-gate design with a straight 4 m long tank. Hydraulics are scaled at 1:20 froude scale and the following controls on frontal wave flow-bed interactions and hence on rapid landscape change are being investigated: 1. Pre-existing mobile sediment effects, fixed bed roughness effects, sediment concentration effects, mobile bed effects. An emphasis is being maintained on examining the downstream temporal and spatial change in physical character of the water / sediment frontal wave. Facilities are state-of-the-art with a fully-automated laser bed-profiler to measure bed elevation after a run, Seatek arrays to measure transient flow

  6. Estimation of Rheological Properties of Viscous Debris Flow Using a Belt Conveyor

    NASA Astrophysics Data System (ADS)

    Hübl, J.; Steinwendtner, H.

    2000-09-01

    Rheological parameters of viscous debris flows are influenced by a great amount of factors and are therefore extremely difficult to estimate. Because of this uncertainties a belt conveyor (conveyor channel) was constructed to measure flow behaviour and rheological properties of natural debris flow material. The upward movement of the smooth rubberised belt between fixed lateral plastic walls causes a stationary wave relative to these bends. This special experimental design enables to study behaviour of viscous ebris flow material with maximum grain diameters up to 20 mm within several minutes and to hold measuring equipment very simple. The conveyor channel was calibrated first with Xanthan, a natural polysaccharide used as thickener in food technology, whose rheological properties are similar to viscous debris flow material. In a second step natural debris flow material was investigated. Velocities and rheological parameters were measured with varying solid concentration and slope of the channel. In cases where concentration of coarse particles exceed around 15% by volume the conveyor channel obtains an alternative to expensive commercial viscometers for determination of rheological parameters of viscous debris flows.

  7. Fleet Debris Levels

    EPA Pesticide Factsheets

    Marine debris degrades ocean habitats, endangers marine and coastal wildlife, causes navigation hazards, results in economic losses to industry and governments, and threatens human health and safety. EPA Pacific Southwest (Region 9) is tapping existing programs and resources to advance the prevention, reduction and clean-up of marine debris in the North Pacific Ocean. EPA Pacific Southwest activities build upon specific recommendations of the Interagency Marine Debris Coordinating Committee by targeting threats and sources of debris and responding to debris impacts. EPA is initiating a three-pronged effort to reduce sources of marine debris, prevent trash from entering the oceans, and assess the human and ecosystem impacts and potential for cleanup.

  8. High temperature reaction between sea salt deposit and (U,Zr)O2 simulated corium debris

    NASA Astrophysics Data System (ADS)

    Takano, Masahide; Nishi, Tsuyoshi

    2013-11-01

    In order to clarify the possible impacts of seawater injection on the chemical and physical state of the corium debris formed in the severe accident at Fukushima Daiichi Nuclear Power Plants, the high temperature reaction between sea salt deposit and (U,Zr)O2 simulated corium debris (sim-debris) was examined in the temperature range from 1088 to 1668 K. A dense layer of calcium and sodium uranate formed on the surface of a sim-debris pellet at 1275 K under airflow, with the thickness of over 50 μm. When the oxygen partial pressure is low, calcium is likely to dissolve into the cubic sim-debris phase to form solid solution (Ca,U,Zr)O2+x. The diffusion depth was 5-6 μm from the surface, subjected to 1275 K for 12 h. The crystalline MgO remains affixed on the surface as the main residue of salt components. A part of it can also dissolve into the sim-debris.

  9. Do Polyethylene Plastic Covers Affect Smoke Emissions from Debris Piles?

    NASA Astrophysics Data System (ADS)

    Weise, D. R.; Jung, H.; Cocker, D.; Hosseini, E.; Li, Q.; Shrivastava, M.; McCorison, M.

    2010-12-01

    Shrubs and small diameter trees exist in the understories of many western forests. They are important from an ecological perspective; however, this vegetation also presents a potential hazard as “ladder fuels” or as a heat source to damage the overstory during prescribed burns. Cutting and piling of this material to burn under safe conditions is a common silvicultural practice. To improve ignition success of the piled debris, polyethylene plastic is often used to cover a portion of the pile. While burning of piled forest debris is an acceptable practice in southern California from an air quality perspective, inclusion of plastic in the piles changes these debris piles to rubbish piles which should not be burned. With support from the four National Forests in southern California, we conducted a laboratory experiment to determine if the presence of polyethylene plastic in a pile of burning wood changed the smoke emissions. Debris piles in southern California include wood and foliage from common forest trees such as sugar and ponderosa pines, white fir, incense cedar, and California black oak and shrubs such as ceanothus and manzanita in addition to forest floor material and dirt. Manzanita wood was used to represent the debris pile in order to control the effects of fuel bed composition. The mass of polyethylene plastic incorporated into the pile was 0, 0.25 and 2.5% of the wood mass—a range representative of field conditions. Measured emissions included NOx, CO, CO2, SO2, polycyclic and light hydrocarbons, carbonyls, particulate matter (5 to 560 nm), elemental and organic carbon. The presence of polyethylene did not alter the emissions composition from this experiment.

  10. The influence of basal-ice debris on patterns and rates of glacial erosion

    NASA Astrophysics Data System (ADS)

    Ugelvig, Sofie V.; Egholm, David L.

    2018-05-01

    Glaciers have played a key role for shaping much of Earth's high topography during the cold periods of the Late Cenozoic. However, despite of their distinct influence on landscapes, the mechanisms of glacial erosion, and the properties that determine their rate of operation, are still poorly understood. Theoretical models of subglacial erosion generally highlight the influence of basal sliding in setting the pace of erosion, but they also point to a strong influence of other subglacial properties, such as effective bed pressure and basal-ice debris concentration. The latter properties are, however, not easily measured in existing glaciers, and hence their influence cannot readily be confirmed by observations. In order to better connect theoretical models for erosion to measurable properties in glaciers, we used computational landscape evolution experiments to study the expected influence of basal-ice debris concentration for subglacial abrasion at the scale of glaciers. The computational experiments couple the two erosion processes of quarrying and abrasion, and furthermore integrate the flow of ice and transport of debris within the ice, thus allowing for the study of dynamic feedbacks between subglacial erosion and systematic glacier-scale variations in basal-ice debris concentration. The experiments explored several physics-based models for glacial erosion, in combination with different models for basal sliding to elucidate the relationship between sliding speed, erosion rate and basal-ice debris concentration. The results demonstrate how differences in debris concentration can explain large variations in measured rates. The experiments also provide a simple explanation for the observed dependence of glacier-averaged rate of erosion on glacier size: that large glacier uplands feed more debris into their lower-elevation parts, thereby strengthening their erosive power.

  11. Investigation of gas-solids flow in a circulating fluidized bed using 3D electrical capacitance tomography

    NASA Astrophysics Data System (ADS)

    Mao, Mingxu; Ye, Jiamin; Wang, Haigang; Yang, Wuqiang

    2016-09-01

    The hydrodynamics of gas-solids flow in the bottom of a circulating fluidized bed (CFB) are complicated. Three-dimensional (3D) electrical capacitance tomography (ECT) has been used to investigate the hydrodynamics in risers of different shapes. Four different ECT sensors with 12 electrodes each are designed according to the dimension of risers, including two circular ECT sensors, a square ECT sensor and a rectangular ECT sensor. The electrodes are evenly arranged in three planes to obtain capacitance in different heights and to reconstruct the 3D images by linear back projection (LBP) algorithm. Experiments were carried out on the four risers using sands as the solids material. The capacitance and differential pressure are measured under the gas superficial velocity from 0.6 m s-1 to 3.0 m s-1 with a step of 0.2 m s-1. The flow regime is investigated according to the solids concentration and differential pressure. The dynamic property of bubbling flows is analyzed theoretically and the performance of the 3D ECT sensors is evaluated. The experimental results show that 3D ECT can be used in the CFB with different risers to predict the hydrodynamics of gas-solids bubbling flows.

  12. Bed texture mapping in large rivers using recreational-grade sidescan sonar

    USGS Publications Warehouse

    Hamill, Daniel; Wheaton, Joseph M.; Buscombe, Daniel D.; Grams, Paul E.; Melis, Theodore S.

    2017-01-01

    The size-distribution and spatial organization of bed sediment, or bed ‘texture’, is a fundamental attribute of natural channels and is one important component of the physical habitat of aquatic ecosystems. ‘Recreational-grade’ sidescan sonar systems now offer the possibility of imaging, and subsequently quantifying bed texture at high resolution with minimal cost, or logistical effort. We are investigating the possibility of using sidescan sonar sensors on commercially available ‘fishfinders’ for within-channel bed-sediment characterization of mixed sand-gravel riverbeds in a debris-fan dominated canyon river. We analyzed repeat substrate mapping of data collected before and after the November 2014 High Flow Experiment on the Colorado River in lower Marble Canyon, Arizona. The mapping analysis resulted in sufficient spatial coverage (e.g. reach) and resolutions (e.g. centrimetric) to inform studies of the effects of changing bed substrates on salmonid spawning on large rivers. From this preliminary study, we argue that the approach could become a tractable and cost-effective tool for aquatic scientists to rapidly obtain bed texture maps without specialized knowledge of hydroacoustics. Bed texture maps can be used as a physical input for models relating ecosystem responses to hydrologic management.

  13. Space Debris Senso

    NASA Image and Video Library

    2017-12-11

    Orbital debris poses a risk to all spacecraft in Earth orbit, so the International Space Station is getting a new debris impact sensor to provide information on the micrometeoroid orbital debris environment in low Earth orbit. The Space Debris Sensor, launching on the next SpaceX Dragon cargo vehicle, will monitor impacts caused by small-scale orbital debris for a period of two to three years. That data will improve station safety by generating a more accurate estimate of the amount of small-scale debris that cannot be tracked from the ground and helping define better spacecraft shielding requirements. _______________________________________ FOLLOW THE SPACE STATION! Twitter: https://twitter.com/Space_Station Facebook: https://www.facebook.com/ISS Instagram: https://instagram.com/iss/

  14. A Hydrodynamic Characteristic of a Dual Fluidized Bed Gasification

    NASA Astrophysics Data System (ADS)

    Sung, Yeon Kyung; Song, Jae Hun; Bang, Byung Ryeul; Yu, Tae U.; Lee, Uen Do

    A cold model dual fluidized bed (DFB) reactor, consisting of two parallel interconnected bubbling and fast fluidized beds, was designed for developing an auto-thermal biomass gasifier. The combustor of this system burns the rest char of the gasification process and provides heat to the gasifier by circulating solids inventory. To find an optimal mixing and circulation of heavy solid inventory and light biomass and char materials, we investigate two types of DFB reactors which have different configuration of distributor and way-out location of the solid inventory and char materials in the gasifier. To determine appropriate operating conditions, we measured minimum fluidization velocity, solid circulation rate, axial solid holdup and gas bypassing between the lower loop seal and the gasifier.

  15. Report on orbital debris

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The success of space endeavors depends upon a space environment sufficiently free of debris to enable the safe and dependable operation of spacecraft. An environment overly cluttered with debris would threaten the ability to utilize space for a wide variety of scientific, technological, military, and commercial purposes. Man made space debris (orbital debris) differs from natural meteoroids because it remains in earth orbit during its lifetime and is not transient through the space around the Earth. The orbital debris environment is considered. The space environment is described along with sources of orbital debris. The current national space policy is examined, along with ways to minimize debris generation and ways to survive the debris environment. International efforts, legal issues and commercial regulations are also examined.

  16. Fluidized-bed combustion reduces atmospheric pollutants

    NASA Technical Reports Server (NTRS)

    Jonke, A. A.

    1972-01-01

    Method of reducing sulfur and nitrogen oxides released during combustion of fossil fuels is described. Fuel is burned in fluidized bed of solids with simultaneous feeding of crushed or pulverized limestone to control emission. Process also offers high heat transfer rates and efficient contacting for gas-solid reactions.

  17. Debris exhaust system

    DOEpatents

    McBride, Donald D.; Bua, Dominic; Domankevitz, Yacov; Nishioka, Norman

    1998-01-01

    A debris removal system removes debris from a work site by flowing fluid away from the work site toward the periphery of a structure. The fluid flow can be kept constant around the periphery so that debris is removed evenly. The structure can have a reduced cross section between the fluid inlet and the work site so that the resulting increased fluid velocity works to prevent debris from escaping.

  18. Debris exhaust system

    DOEpatents

    McBride, D.D.; Bua, D.; Domankevitz, Y.; Nishioka, N.

    1998-06-23

    A debris removal system removes debris from a work site by flowing fluid away from the work site toward the periphery of a structure. The fluid flow can be kept constant around the periphery so that debris is removed evenly. The structure can have a reduced cross section between the fluid inlet and the work site so that the resulting increased fluid velocity works to prevent debris from escaping. 9 figs.

  19. Trends and drivers of marine debris on the Atlantic coast of the United States 1997-2007.

    PubMed

    Ribic, Christine A; Sheavly, Seba B; Rugg, David J; Erdmann, Eric S

    2010-08-01

    For the first time, we documented regional differences in amounts and long-term trends of marine debris along the US Atlantic coast. The Southeast Atlantic had low land-based and general-source debris loads as well as no increases despite a 19% increase in coastal population. The Northeast (8% population increase) also had low land-based and general-source debris loads and no increases. The Mid-Atlantic (10% population increase) fared the worst, with heavy land-based and general-source debris loads that increased over time. Ocean-based debris did not change in the Northeast where the fishery is relatively stable; it declined over the Mid-Atlantic and Southeast and was correlated with declining regional fisheries. Drivers, including human population, land use status, fishing activity, and oceanic current systems, had complex relationships with debris loads at local and regional scales. Management challenges remain undeniably large but solid information from long-term programs is one key to addressing this pressing pollution issue. Published by Elsevier Ltd.

  20. Trends and drivers of marine debris on the Atlantic coast of the United States 1997-2007

    USGS Publications Warehouse

    Ribic, C.A.; Sheavly, S.B.; Rugg, D.J.; Erdmann, Eric S.

    2010-01-01

    For the first time, we documented regional differences in amounts and long-term trends of marine debris along the US Atlantic coast. The Southeast Atlantic had low land-based and general-source debris loads as well as no increases despite a 19% increase in coastal population. The Northeast (8% population increase) also had low land-based and general-source debris loads and no increases. The Mid-Atlantic (10% population increase) fared the worst, with heavy land-based and general-source debris loads that increased over time. Ocean-based debris did not change in the Northeast where the fishery is relatively stable; it declined over the Mid-Atlantic and Southeast and was correlated with declining regional fisheries. Drivers, including human population, land use status, fishing activity, and oceanic current systems, had complex relationships with debris loads at local and regional scales. Management challenges remain undeniably large but solid information from long-term programs is one key to addressing this pressing pollution issue. ?? 2010.

  1. Field and flume investigations of the effects of logjams and woody debris on streambed morphology

    NASA Astrophysics Data System (ADS)

    Leung, V.; Montgomery, D. R.; McHenry, M. L.

    2014-12-01

    Interactions among wood debris, fluid flow and sediment transport in rivers are first-order controls on channel morphodynamics, affecting streambed morphology, sediment transport, sediment storage and aquatic habitat. Woody debris increases the hydraulic and topographic complexity in rivers, leading to a greater diversity of aquatic habitats and an increase in the number of large pools that are important fish habitat and breeding grounds. In the past decade, engineered logjams have become an increasingly used tool in river management for simultaneously decreasing the rate of riverbank migration and improving aquatic habitat. Sediment deposits around woody debris build up riverbanks and counteract bank migration caused by erosion. Previous experiments on flow visualization around model woody debris suggest the amount of sediment scour and deposition are primarily related to the presence of roots and the obstructional area of the woody debris. We present the results of fieldwork and sediment transport experiments of streambed morphology around stationary woody debris. Field surveys on the Hoh River and the Elwha River, WA, measure the local streambed morphology around logjams and individual pieces of woody debris. We quantified the amount of local scour and dam-removal related fine sediment deposition around natural and engineered logjams of varying sizes and construction styles, located in different geomorphic settings. We also quantified the amount of local scour around individual pieces of woody debris of varying sizes, geometries and orientations relative to flow. The flume experiments tested the effects of root geometry and log orientation of individual stationary trees on streambed morphology. The flume contained a deformable sediment bed of medium sand. We find that: 1) the presence of roots on woody debris leads to greater areas of both sediment scour and deposition; and 2) the amount of sediment scour and deposition are related to the wood debris cross

  2. Fluidized bed heating process and apparatus

    NASA Technical Reports Server (NTRS)

    McHale, Edward J. (Inventor)

    1981-01-01

    Capacitive electrical heating of a fluidized bed enables the individual solid particles within the bed to constitute the hottest portion thereof. This effect is achieved by applying an A. C. voltage potential between dielectric coated electrodes, one of which is advantageously the wall of the fluidized bed rejection zone, sufficient to create electrical currents in said particles so as to dissipate heat therein. In the decomposition of silane or halosilanes in a fluidized bed reaction zone, such heating enhances the desired deposition of silicon product on the surface of the seed particles within the fluidized bed and minimizes undesired coating of silicon on the wall of the reaction zone and the homogeneous formation of fine silicon powder within said zone.

  3. Recent advances and results from the solid radiochemistry nuclear diagnostic at the National Ignition Facility

    DOE PAGES

    Gharibyan, N.; Shaughnessy, D. A.; Moody, K. J.; ...

    2016-08-05

    The solid debris collection capability at the National Ignition Facility has been expanded to include a third line-of-sight assembly. The solid radiochemistry nuclear diagnostic measurement of the ratio of gold isotopes is dependent on the efficient collection of neutron-activated hohlraum debris by passive metal disks. As a result, the collection of target debris at this new location is more reliable in comparison to the historic locations, and it appears to be independent of collector surface ablation.

  4. Recent advances and results from the solid radiochemistry nuclear diagnostic at the National Ignition Facility.

    PubMed

    Gharibyan, N; Shaughnessy, D A; Moody, K J; Grant, P M; Despotopulos, J D; Faye, S A; Jedlovec, D R; Yeamans, C B

    2016-11-01

    The solid debris collection capability at the National Ignition Facility has been expanded to include a third line-of-sight assembly. The solid radiochemistry nuclear diagnostic measurement of the ratio of gold isotopes is dependent on the efficient collection of neutron-activated hohlraum debris by passive metal disks. The collection of target debris at this new location is more reliable in comparison to the historic locations, and it appears to be independent of collector surface ablation.

  5. Orbital Debris: A Chronology

    NASA Technical Reports Server (NTRS)

    Portree, Davis S. F. (Editor); Loftus, Joseph P., Jr. (Editor)

    1999-01-01

    This chronology covers the 37-year history of orbital debris concerns. It tracks orbital debris hazard creation, research, observation, experimentation, management, mitigation, protection, and policy. Included are debris-producing, events; U.N. orbital debris treaties, Space Shuttle and space station orbital debris issues; ASAT tests; milestones in theory and modeling; uncontrolled reentries; detection system development; shielding development; geosynchronous debris issues, including reboost policies: returned surfaces studies, seminar papers reports, conferences, and studies; the increasing effect of space activities on astronomy; and growing international awareness of the near-Earth environment.

  6. Universal stability curve for pattern formation in pulsed gas-solid fluidized beds of sandlike particles

    NASA Astrophysics Data System (ADS)

    de Martín, Lilian; Ottevanger, Coen; van Ommen, J. Ruud; Coppens, Marc-Olivier

    2018-03-01

    A granular layer can form regular patterns, such as squares, stripes, and hexagons, when it is fluidized with a pulsating gas flow. These structures are reminiscent of the well-known patterns found in granular layers excited through vibration, but, contrarily to them, they have been hardly explored since they were first discovered. In this work, we investigate experimentally the conditions leading to pattern formation in pulsed fluidized beds and the dimensionless numbers governing the phenomenon. We show that the onset to the instability is universal for Geldart B (sandlike) particles and governed by the hydrodynamical parameters Γ =ua/(utϕ ¯) and f /fn , where ua and f are the amplitude and frequency of the gas velocity, respectively, ut is the terminal velocity of the particles, ϕ ¯ is the average solids fraction, and fn is the natural frequency of the bed. These findings suggest that patterns emerge as a result of a parametric resonance between the kinematic waves originating from the oscillating gas flow and the bulk dynamics. Particle friction plays virtually no role in the onset to pattern formation, but it is fundamental for pattern selection and stabilization.

  7. Apically extruded dentin debris by reciprocating single-file and multi-file rotary system.

    PubMed

    De-Deus, Gustavo; Neves, Aline; Silva, Emmanuel João; Mendonça, Thais Accorsi; Lourenço, Caroline; Calixto, Camila; Lima, Edson Jorge Moreira

    2015-03-01

    This study aims to evaluate the apical extrusion of debris by the two reciprocating single-file systems: WaveOne and Reciproc. Conventional multi-file rotary system was used as a reference for comparison. The hypotheses tested were (i) the reciprocating single-file systems extrude more than conventional multi-file rotary system and (ii) the reciprocating single-file systems extrude similar amounts of dentin debris. After solid selection criteria, 80 mesial roots of lower molars were included in the present study. The use of four different instrumentation techniques resulted in four groups (n = 20): G1 (hand-file technique), G2 (ProTaper), G3 (WaveOne), and G4 (Reciproc). The apparatus used to evaluate the collection of apically extruded debris was typical double-chamber collector. Statistical analysis was performed for multiple comparisons. No significant difference was found in the amount of the debris extruded between the two reciprocating systems. In contrast, conventional multi-file rotary system group extruded significantly more debris than both reciprocating groups. Hand instrumentation group extruded significantly more debris than all other groups. The present results yielded favorable input for both reciprocation single-file systems, inasmuch as they showed an improved control of apically extruded debris. Apical extrusion of debris has been studied extensively because of its clinical relevance, particularly since it may cause flare-ups, originated by the introduction of bacteria, pulpal tissue, and irrigating solutions into the periapical tissues.

  8. Characterizing Dusty Debris Disks with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Chen, Christine; Arriaga, Pauline; Bruzzone, Sebastian; Choquet, Elodie; Debes, John H.; Donaldson, Jessica; Draper, Zachary; Duchene, Gaspard; Esposito, Thomas; Fitzgerald, Michael P.; Golimowski, David A.; Hines, Dean C.; Hinkley, Sasha; Hughes, A. Meredith; Kalas, Paul; Kolokolova, Ludmilla; Lawler, Samantha; Matthews, Brenda C.; Mazoyer, Johan; Metchev, Stanimir A.; Millar-Blanchaer, Max; Moro-Martin, Amaya; Nesvold, Erika; Padgett, Deborah; Patience, Jenny; Perrin, Marshall D.; Pueyo, Laurent; Rantakyro, Fredrik; Rodigas, Timothy; Schneider, Glenn; Soummer, Remi; Song, Inseok; Stark, Chris; Weinberger, Alycia J.; Wilner, David J.

    2017-01-01

    We have been awarded 87 hours of Gemini Observatory time to obtain multi-wavelength observations of HST resolved debris disks using the Gemini Planet Imager. We have executed ~51 hours of telescope time during the 2015B-2016B semesters observing 12 nearby, young debris disks. We have been using the GPI Spec and Pol modes to better constrain the properties of the circumstellar dust, specifically, measuring the near-infrared total intensity and polarization fraction colors, and searching for solid-state spectral features of nearby beta Pic-like disks. We expect that our observations will allow us to break the degeneracy among the particle properties such as composition, size, porosity, and shape. We present some early results from our observations.

  9. Optimization of lipase production by solid-state fermentation of olive pomace: from flask to laboratory-scale packed-bed bioreactor.

    PubMed

    Oliveira, Felisbela; Salgado, José Manuel; Abrunhosa, Luís; Pérez-Rodríguez, Noelia; Domínguez, José M; Venâncio, Armando; Belo, Isabel

    2017-07-01

    Lipases are versatile catalysts with many applications and can be produced by solid-state fermentation (SSF) using agro-industrial wastes. The aim of this work was to maximize the production of Aspergillus ibericus lipase under SSF of olive pomace (OP) and wheat bran (WB), evaluating the effect on lipase production of C/N ratio, lipids, phenols, content of sugars of substrates and nitrogen source addition. Moreover, the implementation of the SSF process in a packed-bed bioreactor and the improvement of lipase extraction conditions were assessed. Low C/N ratios and high content of lipids led to maximum lipase production. Optimum SSF conditions were achieved with a C/N mass ratio of 25.2 and 10.2% (w/w) lipids in substrate, by the mixture of OP:WB (1:1) and supplemented with 1.33% (w/w) (NH 4 ) 2 SO 4 . Studies in a packed-bed bioreactor showed that the lower aeration rates tested prevented substrate dehydration, improving lipase production. In this work, the important role of Triton X-100 on lipase extraction from the fermented solid substrate has been shown. A final lipase activity of 223 ± 5 U g -1 (dry basis) was obtained after 7 days of fermentation.

  10. Field measurement of basal forces generated by erosive debris flows

    USGS Publications Warehouse

    McCoy, S.W.; Tucker, G.E.; Kean, J.W.; Coe, J.A.

    2013-01-01

    It has been proposed that debris flows cut bedrock valleys in steeplands worldwide, but field measurements needed to constrain mechanistic models of this process remain sparse due to the difficulty of instrumenting natural flows. Here we present and analyze measurements made using an automated sensor network, erosion bolts, and a 15.24 cm by 15.24 cm force plate installed in the bedrock channel floor of a steep catchment. These measurements allow us to quantify the distribution of basal forces from natural debris‒flow events that incised bedrock. Over the 4 year monitoring period, 11 debris‒flow events scoured the bedrock channel floor. No clear water flows were observed. Measurements of erosion bolts at the beginning and end of the study indicated that the bedrock channel floor was lowered by 36 to 64 mm. The basal force during these erosive debris‒flow events had a large‒magnitude (up to 21 kN, which was approximately 50 times larger than the concurrent time‒averaged mean force), high‒frequency (greater than 1 Hz) fluctuating component. We interpret these fluctuations as flow particles impacting the bed. The resulting variability in force magnitude increased linearly with the time‒averaged mean basal force. Probability density functions of basal normal forces were consistent with a generalized Pareto distribution, rather than the exponential distribution that is commonly found in experimental and simulated monodispersed granular flows and which has a lower probability of large forces. When the bed sediment thickness covering the force plate was greater than ~ 20 times the median bed sediment grain size, no significant fluctuations about the time‒averaged mean force were measured, indicating that a thin layer of sediment (~ 5 cm in the monitored cases) can effectively shield the subjacent bed from erosive impacts. Coarse‒grained granular surges and water‒rich, intersurge flow had very similar basal force distributions despite

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

    NASA Astrophysics Data System (ADS)

    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

  12. Indigenous microbial capability in solid manure residues to start-up solid-phase anaerobic digesters.

    PubMed

    Yap, S D; Astals, S; Jensen, P D; Batstone, D J; Tait, S

    2017-06-01

    Batch solid-phase anaerobic digestion is a technology for sustainable on-farm treatment of solid residues, but is an emerging technology that is yet to be optimised with respect to start-up and inoculation. In the present study, spent bedding from two piggeries (site A and B) were batch digested at total solids (TS) concentration of 5, 10 and 20% at mesophilic (37°C) and thermophilic (55°C) temperatures, without adding an external inoculum. The results showed that the indigenous microbial community present in spent bedding was able to recover the full methane potential of the bedding (140±5 and 227±6L CH 4 kgVS fed -1 for site A and B, respectively), but longer treatment times were required than for digestion with an added external inoculum. Nonetheless, at high solid loadings (i.e. TS level>10%), the digestion performance was affected by chemical inhibition due to ammonia and/or humic acid. Thermophilic temperatures did not influence digestion performance but did increase start-up failure risk. Further, inoculation of residues from the batch digestion to subsequent batch enhanced start-up and achieved full methane potential recovery of the bedding. Inoculation with liquid residue (leachate) was preferred over a solid residue, to preserve treatment capacity for fresh substrate. Overall, the study highlighted that indigenous microbial community in the solid manure residue was capable of recovering full methane potential and that solid-phase digestion was ultimately limited by chemical inhibition rather than lack of suitable microbial community. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Thermal treatment of electronic waste in a fluidised bed and chemical digestion of solid products.

    PubMed

    Woynarowska, Amelia; Żukowski, Witold; Żelazny, Sylwester

    2016-07-01

    The article presents the results of e-waste thermal treatment in a fluidised bed reactor and solid products digestion under acidic conditions. During the processes, measurements of carbon monoxide, carbon dioxide, volatile organic compounds, nitrogen oxides, sulphur dioxide, hydrogen chloride, hydrogen bromide, hydrogen cyanide, ammonia, phenol, aliphatic and aromatic hydrocarbons, hydrogen fluoride and phosgene were carried out. Several digestion tests of the solid residue in sulphuric acid (VI) at 25 °C-65 °C, for 55 min-24 h were conducted. In each case, the dilution method was used, i.e. preliminary digestion in concentrated sulphuric acid (VI) (95%) for 40 min, and then dilution to expected concentrations (30%-50%). Most preferred results were obtained using sulphuric acid (VI) with a target concentration of 40% at 65 °C, where the leaching degrees were 76.56% for copper, 71.67% for iron, 91.89% for zinc and 97.40% for tin. The time necessary to effectively carry out the digestion process was 220 min. © The Author(s) 2016.

  14. Orbital debris issues

    NASA Technical Reports Server (NTRS)

    Kessler, D. J.

    1985-01-01

    Man-made orbital debris, identified as a potential hazard to future space activities, is grouped into size categories. At least 79 satellites have broken up in orbit to date and, in combination with exploded rocket casings and antisatellite debris, threaten 10 km/sec collisions with other orbiting platforms. Only 5 percent of the debris is connected to payloads. The total population of orbiting objects over 4 cm in diameter could number as high as 15,000, and at 1 cm in diameter could be 32,000, based on NASA and NORAD studies. NASA has initiated the 10 yr Space Debris Assessment Program to characterize the hazards of orbiting debris, the potential damage to typical spacecraft components, and to identify means of controlling the damage.

  15. "State of the Art" of technical protection measures in Austria and the effectiveness documented during bedload and debris flow events

    NASA Astrophysics Data System (ADS)

    Moser, Markus; Mehlhorn, Susanne; Rudolf-Miklau, Florian; Suda, Jürgen

    2017-04-01

    Since the beginning of systematic torrent control in Austria 130 years ago, barriers are constructed for protection purposes. Until the end of the 1960s, solid barriers were built at the exits of depositional areas to prevent dangerous debris flows from reaching high consequence areas. The development of solid barriers with large slots or slits to regulate sediment transport began with the use of reinforced concrete during the 1970s (Rudolf-Miklau, Suda 2011). In order to dissipate the energy of debris flows debris flow breakers have been designed since the 1980s. By slowing and depositing the surge front of the debris flow, downstream reaches of the stream channel and settlement areas should be exposed to considerably lower dynamic impact. In the past, the technological development of these constructions was only steered by the experiences of the engineering practice while an institutionalized process of standardization comparable to other engineering branches was not existent. In future all structures have to be designed and dimensioned according to the EUROCODE standards. This was the reason to establish an interdisciplinary working group (ON-K 256) at the Austrian Standards Institute (ASI), which has managed to developed comprehensive new technical standards for torrent control engineering, including load models, design, dimensioning and life cycle assessment of torrent control works (technical standard ONR 24800 - series). Extreme torrential events comprise four definable displacement processes floods; fluvial solid transport; hyper-concentrated solid transport (debris floods) and debris flow (stony debris flow or mud-earth flow). As a rule, the design of the torrential barriers has to follow its function (Kettl, 1984). Modern protection concepts in torrent control are scenario-oriented and try to optimize different functions in a chain of protections structures (function chain). More or less the first step for the designing the optimal construction type is

  16. Roll Call Debris - Race

    EPA Pesticide Factsheets

    Marine debris degrades ocean habitats, endangers marine and coastal wildlife, causes navigation hazards, results in economic losses to industry and governments, and threatens human health and safety. EPA Pacific Southwest (Region 9) is tapping existing programs and resources to advance the prevention, reduction and clean-up of marine debris in the North Pacific Ocean. EPA Pacific Southwest activities build upon specific recommendations of the Interagency Marine Debris Coordinating Committee by targeting threats and sources of debris and responding to debris impacts. EPA is initiating a three-pronged effort to reduce sources of marine debris, prevent trash from entering the oceans, and assess the human and ecosystem impacts and potential for cleanup.

  17. Special Report Debris - Race

    EPA Pesticide Factsheets

    Marine debris degrades ocean habitats, endangers marine and coastal wildlife, causes navigation hazards, results in economic losses to industry and governments, and threatens human health and safety. EPA Pacific Southwest (Region 9) is tapping existing programs and resources to advance the prevention, reduction and clean-up of marine debris in the North Pacific Ocean. EPA Pacific Southwest activities build upon specific recommendations of the Interagency Marine Debris Coordinating Committee by targeting threats and sources of debris and responding to debris impacts. EPA is initiating a three-pronged effort to reduce sources of marine debris, prevent trash from entering the oceans, and assess the human and ecosystem impacts and potential for cleanup.

  18. Space Shuttle Debris Transport

    NASA Technical Reports Server (NTRS)

    Gomez, Reynaldo J., III

    2010-01-01

    This slide presentation reviews the assessment of debris damage to the Space Shuttle, and the use of computation to assist in the space shuttle applications. The presentation reviews the sources of debris, a mechanism for determining the probability of damaging debris impacting the shuttle, tools used, eliminating potential damaging debris sources, the use of computation to assess while inflight damage, and a chart showing the applications that have been used on increasingly powerful computers simulate the shuttle and the debris transport.

  19. Association between stall surface and some animal welfare measurements in freestall dairy herds using recycled manure solids for bedding.

    PubMed

    Husfeldt, A W; Endres, M I

    2012-10-01

    The objective of this cross-sectional study was to investigate the association between stall surface and some animal welfare measurements in upper Midwest US dairy operations using recycled manure solids as bedding material. The study included 34 dairy operations with herd sizes ranging from 130 to 3,700 lactating cows. Forty-five percent of the herds had mattresses and 55% had deep-bedded stalls. Farms were visited once between July and October 2009. At the time of visit, at least 50% of the cows in each lactating pen were scored for locomotion, hygiene, and hock lesions. On-farm herd records were collected for the entire year and used to investigate mortality, culling, milk production, and mastitis incidence. Stall surface was associated with lameness and hock lesion prevalence. Lameness prevalence (locomotion score ≥ 3 on a 1 to 5 scale) was lower in deep-bedded freestalls (14.4%) than freestalls with mattresses (19.8%). Severe lameness prevalence (locomotion score ≥ 4) was also lower for cows housed in deep-bedded freestalls (3.6%) than for cows housed in freestalls with mattresses (5.9%). In addition, the prevalence of hock lesions (hock lesion scores ≥ 2 on a 1 to 3 scale, with 1=no lesion, 2=hair loss or mild lesion, and 3=swelling or severe lesion) and severe hock lesions (hock lesion score=3) was lower in herds with deep-bedded freestalls (49.4%; 6.4%) than in herds with mattresses (67.3%; 13.2%). Herd turnover rates were not associated with stall surface; however, the percentage of removals due to voluntary (low milk production, disposition, and dairy) and involuntary (death, illness, injury, and reproductive) reasons was different between deep-bedded and mattress-based freestalls. Voluntary removals averaged 16% of all herd removals in deep-bedded herds, whereas in mattress herds, these removals were 8%. Other welfare measurements such as cow hygiene, mortality rate, mastitis incidence, and milk production were not associated with stall surface

  20. Multi-gene genetic programming based predictive models for municipal solid waste gasification in a fluidized bed gasifier.

    PubMed

    Pandey, Daya Shankar; Pan, Indranil; Das, Saptarshi; Leahy, James J; Kwapinski, Witold

    2015-03-01

    A multi-gene genetic programming technique is proposed as a new method to predict syngas yield production and the lower heating value for municipal solid waste gasification in a fluidized bed gasifier. The study shows that the predicted outputs of the municipal solid waste gasification process are in good agreement with the experimental dataset and also generalise well to validation (untrained) data. Published experimental datasets are used for model training and validation purposes. The results show the effectiveness of the genetic programming technique for solving complex nonlinear regression problems. The multi-gene genetic programming are also compared with a single-gene genetic programming model to show the relative merits and demerits of the technique. This study demonstrates that the genetic programming based data-driven modelling strategy can be a good candidate for developing models for other types of fuels as well. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Shielding against debris

    NASA Technical Reports Server (NTRS)

    Cour-Palais, Burton G.; Avans, Sherman L.

    1988-01-01

    The damage to spacecraft caused by debris and design of the Space Station to minimize damage from debris are discussed. Although current estimates of the debris environment show that fragments bigger than 2 cm are not likely to hit the Space Station, orbital debris from about 0.5 mm to 2 cm will pose a hazard, especially on brittle surfaces, such as glass. Spacesuits are being designed to reduce debris caused dangers to astronauts during EVA. About 5 cm of high-strength aluminum are needed to prevent penetration by a 1 cm piece of aluminum with a mass near 1.5 g colliding at 10 km/sec. Because aluminum bumpers have the drawback of metallic debris ejected outward after a hypervelocity collision, the use of nonmetallic materials for bumpers is being studied. Methods of reducing the weight and volume of the shield for the Space Station are also being researched. A space station habitation module using bumpers has a 99.6 percent chance of avoiding penetration during its lifetime.

  2. Effect of excess pore pressure on the long runout of debris flows over low gradient channels: A case study of the Dongyuege debris flow in Nu River, China

    NASA Astrophysics Data System (ADS)

    Zhou, Zhen-Hua; Ren, Zhe; Wang, Kun; Yang, Kui; Tang, Yong-Jun; Tian, Lin; Xu, Ze-Min

    2018-05-01

    Debris flows with long reaches are one of the major natural hazards to human life and property on alluvial fans, as shown by the debris flow that occurred in the Dongyuege (DYG) Gully in August 18, 2010, and caused 96 deaths. The travel distance and the runout distance of the DYG large-scale tragic debris flow were 11 km and 9 km, respectively. In particular, the runout distance over the low gradient channel (channel slope < 5°) upstream of the depositional fan apex reached up to 3.3 km. The build-up and maintenance of excess pore pressure in the debris-flow mass might have played a crucial role in the persistence and long runout of the bouldery viscous debris flow. Experiments to measure pore pressure and pore water escape have been carried out by reconstituting the debris flow bodies with the DYG debris flow deposit. The slurrying of the debris is governed by solid volumetric concentration (SVC), and the difference between the lower SVC limit and the upper SVC limit can be defined as debris flow index (Id). Peak value (Kp) and rate of dissipation (R) of relative excess pore pressure are dependent on SVC. Further, the SVC that gives the lowest rate of dissipation is regarded as the optimum SVC (Cvo). The dissipation response of excess pore pressure can be characterized by the R value under Cvo at a given moment (i.e., 0.5 h, 1 h or 2 h later after peak time). The results reveal that a relatively high level of excess pore pressure developed within the DYG debris-flow mass and had a strong persistence capability. Further research shows that the development, peak value and dissipation of excess pore pressure in a mixture of sediment and water are related to the maximum grain size (MGS), gradation and mineralogy of clay-size particles of the sediment. The layer-lattice silicates in clay particles can be the typical clay minerals, including kaolinite, montmorillonite and illite, and also the unrepresentative clay minerals such as muscovite and chlorite. Moreover

  3. Young Debris Disks With Newly Discovered Emission Features

    NASA Astrophysics Data System (ADS)

    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

  4. Channel geometry change of a first-order stream after a small debris flow in Ashio Mountains of central Japan

    NASA Astrophysics Data System (ADS)

    Hattanji, T.; Wasklewicz, T.

    2006-12-01

    We examined geometry change of a steep first-order channel with a laserscanner before and after a small debris flow. The study site is located in chert area, Ashio Mountains, Japan. On August 12, 2005, a 20-year storm event with maximum 1-hour rainfall of 75.4 mm/h triggered a small landslide at a steep channel head. The sliding material moved as a debris flow along the first-order channel (C3) to the mouth. We successfully measured high-resolution channel topography with the Leica Geosystems High-Definition Surveying Laser Scanner before (April 30) and after the debris-flow event (October 9-11). Width, depth and other related parameters were measured for 30 selected cross sections. Bankfull stage of this first-order channel after the debris-flow event is much higher than two-year flood stage. The magnitude of channel geometry change varies non-linearly in downstream direction. The non-linear variability is attributed to differences in stream bed and bank characteristics. Bedrock-channel reach is less impacted by the debris flow. The largest magnitude changes in the channel geometry parameters occur along colluvially confined channel reaches.

  5. Capture of a recombinant protein from unclarified canola extract using streamline expanded bed anion exchange.

    PubMed

    Bai, Yun; Glatz, Charles E

    2003-03-30

    The feasibility of applying expanded bed adsorption technology to recombinant protein recovery from extracts of transgenic canola (rapeseed) was assessed. The extraction step results in a suspension of high solids content that is difficult to clarify. The coarse portion of the solids can be removed easily, and our aim was to operate the expanded bed in the presence of the recalcitrant particulates. Recombinant beta-glucuronidase (rGUS) produced in transgenic canola seed was the model system. Diethylaminoethyl (DEAE) and Streamline DEAE resin exhibited similar binding and elution properties for both rGUS and native canola proteins. More than 95% of native canola proteins did not bind to DEAE resins at pH 7.5, whereas the bound proteins were fractionated by two-step salt elution into two groups with the first peak, containing 70% of total bound proteins, at 20 mS/cm, followed by elution of rGUS at 50 mS/cm. The adsorption isotherm was only slightly influenced by the presence of up to 14 mg solids/mL extract; C(m) and K(d) changed by -1% and +39%, respectively. Bed expansion was semiquantitatively predictable from physical properties of the fluid together with Stokes's law and the Richardson-Zaki correlation for both clarified and partially clarified extracts. The presence of 1.4% solids did not change rGUS breakthrough behavior of the expanded bed; however, a small difference between expanded bed and packed bed was observed early in the sample loading stage, during which bed expansion adjusts. Canola solids moved through the column in approximately plug flow with no detriment to bed stability. Seventy-two percent recovery of 34-fold purified rGUS was obtained after initial loading of 1.4% (w/w) solids extract to 25% breakthrough. Copyright 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 855-864, 2003.

  6. Research on acting mechanism and behavior of a gas bubble in the air dense medium fluidized bed

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tao, X.; Chen, Q.; Yang, Y.

    1996-12-31

    Coal dry beneficiation with air-dense medium fluidized bed has now been established as a high efficiency dry separation technology, it is the application of fluidization technology to the coal preparation field. The tiny particle media forms an uniform and stable fluidized bed with a density acted by airflow, which is used to separate 80{micro}m to {approximately}6mm size coal. This technology has achieved satisfied industrialization results, and attracted the expert`s attention in the field. In fluidized bed, the interaction between gas and solid was mainly decided by the existence state of heavy media particles mass (position and distance) relative velocity ofmore » gas-solid two phase, as well turbulent action. A change of vertical gas-solid fluidizing state essentially is the one of a energy transforming process. For a coal separating process with air-dense medium fluidized bed, the gas bubble, producing a turbulent and stirring action in the bed, leads to two effects. It can promote a uniform distribution of heavy media particles, and a uniform and stability of a bed density. Otherwise it will decrease effective contacts between gas-solids two phases, producing a bigger gas bubble. Therefore controlling a gas bubble size in bed should be optimized. This paper analyzes mutual movement between gas-solid, and studies the gas bubble behavior in the bed. A mechanic mode and a separating process of coal in the bed is discussed. It aims to research the coal separating mechanism with air-dense fluidized bed.« less

  7. Flow-sediment-large woody debris interplay: Introducing an appropriately scaled laboratory experiment

    NASA Astrophysics Data System (ADS)

    Friedrich, H.; Spreitzer, G.; Tunnicliffe, J. F.

    2017-12-01

    The morphology of steep (>0.01 m/m) forested streams is governed not only by water-sediment interplay, but also by accumulations of coarse and fine organic debris. In this project we look at the jamming dynamics (formation, persistence and hydraulic feedbacks) of large woody debris with the help of scaled laboratory experiments. In New Zealand, the recruitment of wood from both natural tree-fall and forest harvesting has led to obstruction of culverts, bridges and other river constrictions. Understanding the dynamics of jam formation and persistence is important for harvest practice guidelines, management of sediment accumulation, as well as establishing impacts to habitat and infrastructure. In this study, we provide the context of our work, present our experimental setup for studying the complex flow-sediment-wood interactions and present some initial results. In our experimental setup, we varied feed rates of sediment and organic fine material in order to establish concentration thresholds for jam formation, and development of sediment retention capacity upstream of the jam. Large woody debris accumulation is studied for different blocking scenarios, and the effect on sediment transport is measured. Sediment quantities and changes in channel bed morphology upstream of the critical cross section are evaluated, together with resulting backwater effects, and associated energy losses. In the long term, our results will inform our understanding of the processes that take place from the mobilization of woody debris to accumulation.

  8. A debris flow deposit in alluvial, coal-bearing facies, Bighorn Basin, Wyoming, USA: Evidence for catastrophic termination of a mire

    USGS Publications Warehouse

    Roberts, S.B.; Stanton, R.W.; Flores, R.M.

    1994-01-01

    Coal and clastic facies investigations of a Paleocene coal-bearing succession in the Grass Creek coal mine, southwestern Bighorn Basin, Wyoming, USA, suggest that disruption of peat accumulation in recurrent mires was caused by the repetitive progradation of crevasse splays and, ultimately, by a catastrophic mass movement. The mass movement, represented by deposits of debris flow, marked the termination of significant peat accumulation in the Grass Creek coal mine area. Megascopic and microscopic analyses of coal beds exposed along the mine highwalls suggest that these deposits developed in low-lying mires, as evidenced primarily by their ash yields and maceral composition. Disruption of peat accumulation in successive mires was caused by incursions of sediment into the mire environments. Termination by crevasse splay progradation is represented by coarsening-upward successions of mudrock and tabular, rooted sandstone, which overlie coal beds in the lower part of the coal-bearing interval. A more rapid process of mire termination by mass movement is exemplified by a debris flow deposit of diamictite, which overlies the uppermost coal bed at the top of the coal-bearing interval. The diamictite consists of a poorly sorted, unstratified mixture of quartzite cobbles and pebbles embedded in a claystone-rich or sandy mudstone matrix. Deposition of the diamictite may have taken place over a matter of weeks, days, or perhaps even hours, by catastrophic flood, thus reflecting an instantaneous process of mire termination. Coarse clastics and mud were transported from the southwest some 20-40 km as a viscous debris flow along stream courses from the ancestral Washakie Range to the Grass Creek area, where the flow overrode a low-lying mire and effectively terminated peat accumulation. ?? 1994.

  9. RemoveDEBRIS: An in-orbit active debris removal demonstration mission

    NASA Astrophysics Data System (ADS)

    Forshaw, Jason L.; Aglietti, Guglielmo S.; Navarathinam, Nimal; Kadhem, Haval; Salmon, Thierry; Pisseloup, Aurélien; Joffre, Eric; Chabot, Thomas; Retat, Ingo; Axthelm, Robert; Barraclough, Simon; Ratcliffe, Andrew; Bernal, Cesar; Chaumette, François; Pollini, Alexandre; Steyn, Willem H.

    2016-10-01

    Since the beginning of the space era, a significant amount of debris has progressively been generated. Most of the objects launched into space are still orbiting the Earth and today these objects represent a threat as the presence of space debris incurs risk of collision and damage to operational satellites. A credible solution has emerged over the recent years: actively removing debris objects by capturing them and disposing of them. This paper provides an update to the mission baseline and concept of operations of the EC FP7 RemoveDEBRIS mission drawing on the expertise of some of Europe's most prominent space institutions in order to demonstrate key active debris remove (ADR) technologies in a low-cost ambitious manner. The mission will consist of a microsatellite platform (chaser) that ejects 2 CubeSats (targets). These targets will assist with a range of strategically important ADR technology demonstrations including net capture, harpoon capture and vision-based navigation using a standard camera and LiDAR. The chaser will also host a drag sail for orbital lifetime reduction. The mission baseline has been revised to take into account feedback from international and national space policy providers in terms of risk and compliance and a suitable launch option is selected. A launch in 2017 is targeted. 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.

  10. NESC Peer-Review of the Flight Rationale for Expected Debris Report. Version 1.0

    NASA Technical Reports Server (NTRS)

    Harris, Charles E.; Raju, Ivatury S.; Stadler, John H.; Piascik, Robert S.; Kramer-White, Julie A.; Labbe, Steve G.; Ungar, Eugene K.; Rotter, Hank A.; Rogers, James H.; Null, Cynthia H.

    2005-01-01

    Since the loss of Columbia on February 1, 2003, the Space Shuttle Program (SSP) has significantly improved the understanding of launch and ascent debris, implemented hardware modifications to reduce debris, and conducted tests and analyses to understand the risks associated with expected debris. The STS-114 flight rationale for expected debris relies on a combination of all three of these factors. A number of design improvements have been implemented to reduce debris at the source. The External Tank (ET) thermal protection system (TPS) foam has been redesigned and/or process improvements have been implemented in the following locations: the bipod closeout, the first ten feet of the liquid hydrogen (LH2) tank protuberance air load (PAL) ramp, and the LH2 tank-to-intertank flange closeout. In addition, the forward bipod ramp has been eliminated and heaters have been installed on the bipod fittings and the liquid oxygen (LO2) feedline forward bellows to prevent ice formation. The Solid Rocket Booster (SRB) bolt catcher has been redesigned. The Orbiter reaction control system (RCS) thruster cover "butcher paper" has been replaced with a material that sheds at a low velocity. Finally, the pad area has been cleaned to reduce debris during lift-off.

  11. Artificial neural network based modelling approach for municipal solid waste gasification in a fluidized bed reactor.

    PubMed

    Pandey, Daya Shankar; Das, Saptarshi; Pan, Indranil; Leahy, James J; Kwapinski, Witold

    2016-12-01

    In this paper, multi-layer feed forward neural networks are used to predict the lower heating value of gas (LHV), lower heating value of gasification products including tars and entrained char (LHV p ) and syngas yield during gasification of municipal solid waste (MSW) during gasification in a fluidized bed reactor. These artificial neural networks (ANNs) with different architectures are trained using the Levenberg-Marquardt (LM) back-propagation algorithm and a cross validation is also performed to ensure that the results generalise to other unseen datasets. A rigorous study is carried out on optimally choosing the number of hidden layers, number of neurons in the hidden layer and activation function in a network using multiple Monte Carlo runs. Nine input and three output parameters are used to train and test various neural network architectures in both multiple output and single output prediction paradigms using the available experimental datasets. The model selection procedure is carried out to ascertain the best network architecture in terms of predictive accuracy. The simulation results show that the ANN based methodology is a viable alternative which can be used to predict the performance of a fluidized bed gasifier. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Meat and bone meal as secondary fuel in fluidized bed combustion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    L. Fryda; K. Panopoulos; P. Vourliotis

    2007-07-01

    Meat and Bone Meal (MBM) was co-fired in a laboratory scale fluidized bed combustion (FBC) apparatus with two coals. Several fuel blends were combusted under different conditions to study how primary fuel substitution by MBM affects flue gas emissions as well as fluidized bed (FB) agglomeration tendency. MBM, being a highly volatile fuel, caused significant increase of CO emissions and secondary air should be used in industrial scale applications to conform to regulations. The high N-content of MBM is moderately reflected on the increase of nitrogen oxides emissions which are reduced by MBM derived volatiles. The MBM ash, mainly containingmore » bone material rich in Ca, did not create any noteworthy desulphurization effect. The observed slight decrease in SO{sub 2} emissions is predominantly attributed to the lower sulphur content in the coal/MBM fuel mixtures. The SEM/EDS analysis of bed material samples from the coal/MBM tests revealed the formation of agglomerates of bed material debris and ash with sizes that do not greatly exceed the original bed inventory and thus not problematic. 37 refs., 9 figs., 3 tabs.« less

  13. Origin of the Bear Gulch Beds (Namurian, Montana, USA)

    USGS Publications Warehouse

    Feldman, H.R.; Lund, R.; Maples, C.G.; Archer, A.W.

    1994-01-01

    The Bear Gulch Beds of the Heath Formation are well known for their diverse and well-preserved assemblage offish, arthropods, and soft-bodied animals (they constitute a Lagersta??tte). The Bear Gulch is a lens of lithographic limestone (approximately 12 km in lateral extent and up to 30 m thick) surrounded by black, platy shale. The lens is composed primarily of alternating massive beds (up to 25 cm thick) and argillaceous platy beds (up to 30 cm thick). Platy and massive beds are both composed primarily of normally graded laminations (1-15 mm thick). Laminations typically have sharp bases and grade upward from microspar to micrite. Lateral continuity of individual beds (at least 1 km) and laminations (at least 500 m), lack of evidence of bottom currents, and paucity of erosional features all suggest a quiet-water environment. Fossils are generally rare in the Bear Gulch Beds. The most common fossils in most beds are cephalopods, shrimp, fish, and soft-bodied organisms. Rare beds contain abundant benthic fossils including brachiopods, sponges, bivalves, conulariids, and crinoids. Fish preservation ranges from completely articulated with traces of internal organs and preserved color patterns to completely disarticulated, however most fish are well preserved. Fish and shrimp occur at the boundaries between laminations. Preservational quality of fossils and presence of abundant dewatering structures suggest rapid deposition. Lack of normal-marine shelly fossils in most beds may indicate stressful conditions at the seafloor, however some fish and shrimp were apparently well adapted for a benthic habitat. No evidence of current-modified fish debris has been observed and only rarely are fish aligned on a single bedding plane. Conditions at the seafloor were calm, possibly inhospitable, but frequently disturbed by rapid depositional events. The mechanism of deposition of the laminations remains enigmatic. ?? 1994.

  14. Rainfall threshold calculation for debris flow early warning in areas with scarcity of data

    NASA Astrophysics Data System (ADS)

    Pan, Hua-Li; Jiang, Yuan-Jun; Wang, Jun; Ou, Guo-Qiang

    2018-05-01

    Debris flows are natural disasters that frequently occur in mountainous areas, usually accompanied by serious loss of lives and properties. One of the most commonly used approaches to mitigate the risk associated with debris flows is the implementation of early warning systems based on well-calibrated rainfall thresholds. However, many mountainous areas have little data regarding rainfall and hazards, especially in debris-flow-forming regions. Therefore, the traditional statistical analysis method that determines the empirical relationship between rainstorms and debris flow events cannot be effectively used to calculate reliable rainfall thresholds in these areas. After the severe Wenchuan earthquake, there were plenty of deposits deposited in the gullies, which resulted in several debris flow events. The triggering rainfall threshold has decreased obviously. To get a reliable and accurate rainfall threshold and improve the accuracy of debris flow early warning, this paper developed a quantitative method, which is suitable for debris flow triggering mechanisms in meizoseismal areas, to identify rainfall threshold for debris flow early warning in areas with a scarcity of data based on the initiation mechanism of hydraulic-driven debris flow. First, we studied the characteristics of the study area, including meteorology, hydrology, topography and physical characteristics of the loose solid materials. Then, the rainfall threshold was calculated by the initiation mechanism of the hydraulic debris flow. The comparison with other models and with alternate configurations demonstrates that the proposed rainfall threshold curve is a function of the antecedent precipitation index (API) and 1 h rainfall. To test the proposed method, we selected the Guojuanyan gully, a typical debris flow valley that during the 2008-2013 period experienced several debris flow events, located in the meizoseismal areas of the Wenchuan earthquake, as a case study. The comparison with other

  15. Orbital Debris: A Policy Perspective

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2007-01-01

    A viewgraph presentation describing orbital debris from a policy perspective is shown. The contents include: 1) Voyage through near-Earth Space-animation; 2) What is Orbital Debris?; 3) Orbital Debris Detectors and Damage Potential; 4) Hubble Space Telescope; 5) Mir Space Station Solar Array; 6) International Space Station; 7) Space Shuttle; 8) Satellite Explosions; 9) Satellite Collisions; 10) NASA Orbital Debris Mitigation Guidelines; 11) International Space Station Jettison Policy; 12) Controlled/Uncontrolled Satellite Reentries; 13) Return of Space Objects; 14) Orbital Debris and U.S. National Space Policy; 15) U.S Government Policy Strategy; 16) Bankruptcy of the Iridium Satellite System; 17) Inter-Agency Space Debris Coordination Committee (IADC); 18) Orbital Debris at the United Nations; 19) Chinese Anti-satellite System; 20) Future Evolution of Satellite Population; and 21) Challenge of Orbital Debris

  16. Flow resistance dynamics in step‐pool channels: 2. Partitioning between grain, spill, and woody debris resistance

    USGS Publications Warehouse

    Wilcox, Andrew C.; Nelson, Jonathan M.; Wohl, Ellen E.

    2006-01-01

    In step‐pool stream channels, flow resistance is created primarily by bed sediments, spill over step‐pool bed forms, and large woody debris (LWD). In order to measure resistance partitioning between grains, steps, and LWD in step‐pool channels we completed laboratory flume runs in which total resistance was measured with and without grains and steps, with various LWD configurations, and at multiple slopes and discharges. Tests of additive approaches to resistance partitioning found that partitioning estimates are highly sensitive to the order in which components are calculated and that such approaches inflate the values of difficult‐to‐measure components that are calculated by subtraction from measured components. This effect is especially significant where interactions between roughness features create synergistic increases in resistance such that total resistance measured for combinations of resistance components greatly exceeds the sum of those components measured separately. LWD contributes large proportions of total resistance by creating form drag on individual pieces and by increasing the spill resistance effect of steps. The combined effect of LWD and spill over steps was found to dominate total resistance, whereas grain roughness on step treads was a small component of total resistance. The relative contributions of grain, spill, and woody debris resistance were strongly influenced by discharge and to a lesser extent by LWD density. Grain resistance values based on published formulas and debris resistance values calculated using a cylinder drag approach typically underestimated analogous flume‐derived values, further illustrating sources of error in partitioning methods and the importance of accounting for interaction effects between resistance components.

  17. Flow resistance dynamics in step-pool channels: 2. Partitioning between grain, spill, and woody debris resistance

    NASA Astrophysics Data System (ADS)

    Wilcox, Andrew C.; Nelson, Jonathan M.; Wohl, Ellen E.

    2006-05-01

    In step-pool stream channels, flow resistance is created primarily by bed sediments, spill over step-pool bed forms, and large woody debris (LWD). In order to measure resistance partitioning between grains, steps, and LWD in step-pool channels we completed laboratory flume runs in which total resistance was measured with and without grains and steps, with various LWD configurations, and at multiple slopes and discharges. Tests of additive approaches to resistance partitioning found that partitioning estimates are highly sensitive to the order in which components are calculated and that such approaches inflate the values of difficult-to-measure components that are calculated by subtraction from measured components. This effect is especially significant where interactions between roughness features create synergistic increases in resistance such that total resistance measured for combinations of resistance components greatly exceeds the sum of those components measured separately. LWD contributes large proportions of total resistance by creating form drag on individual pieces and by increasing the spill resistance effect of steps. The combined effect of LWD and spill over steps was found to dominate total resistance, whereas grain roughness on step treads was a small component of total resistance. The relative contributions of grain, spill, and woody debris resistance were strongly influenced by discharge and to a lesser extent by LWD density. Grain resistance values based on published formulas and debris resistance values calculated using a cylinder drag approach typically underestimated analogous flume-derived values, further illustrating sources of error in partitioning methods and the importance of accounting for interaction effects between resistance components.

  18. Orbital debris: A technical assessment

    NASA Technical Reports Server (NTRS)

    Gleghorn, George; Asay, James; Atkinson, Dale; Flury, Walter; Johnson, Nicholas; Kessler, Donald; Knowles, Stephen; Rex, Dietrich; Toda, Susumu; Veniaminov, Stanislav

    1995-01-01

    To acquire an unbiased technical assessment of (1) the research needed to better understand the debris environment, (2) the necessity and means of protecting spacecraft against the debris environment, and (3) potential methods of reducing the future debris hazard, NASA asked the National Research Council to form an international committee to examine the orbital debris issue. The committee was asked to draw upon available data and analyses to: characterize the current debris environment, project how this environment might change in the absence of new measures to alleviate debris proliferation, examine ongoing alleviation activities, explore measures to address the problem, and develop recommendations on technical methods to address the problems of debris proliferation.

  19. Numerical simulation of the debris flow dynamics with an upwind scheme and specific friction treatment

    NASA Astrophysics Data System (ADS)

    Sánchez Burillo, Guillermo; Beguería, Santiago; Latorre, Borja; Burguete, Javier

    2014-05-01

    Debris flows, snow and rock avalanches, mud and earth flows are often modeled by means of a particular realization of the so called shallow water equations (SWE). Indeed, a number of simulation models have been already developed [1], [2], [3], [4], [5], [6], [7]. Debris flow equations differ from shallow water equations in two main aspects. These are (a) strong bed gradient and (b) rheology friction terms that differ from the traditional SWE. A systematic analysis of the numerical solution of the hyperbolic system of equations rising from the shallow water equations with different rheological laws has not been done. Despite great efforts have been done to deal with friction expressions common in hydraulics (such as Manning friction), landslide rheologies are characterized by more complicated expressions that may deal to unphysical solutions if not treated carefully. In this work, a software that solves the time evolution of sliding masses over complex bed configurations is presented. The set of non- linear equations is treated by means of a first order upwind explicit scheme, and the friction contribution to the dynamics is treated with a suited numerical scheme [8]. In addition, the software incorporates various rheological models to accommodate for different flow types, such as the Voellmy frictional model [9] for rock and debris avalanches, or the Herschley-Bulkley model for debris and mud flows. The aim of this contribution is to release this code as a free, open source tool for the simulation of mass movements, and to encourage the scientific community to make use of it. The code uses as input data the friction coefficients and two input files: the topography of the bed and the initial (pre-failure) position of the sliding mass. In addition, another file with the final (post-event) position of the sliding mass, if desired, can be introduced to be compared with the simulation obtained result. If the deposited mass is given, an error estimation is computed by

  20. Orbital Debris

    NASA Technical Reports Server (NTRS)

    Kessler, D. J. (Compiler); Su, S. Y. (Compiler)

    1985-01-01

    Earth orbital debris issues and recommended future activities are discussed. The workshop addressed the areas of environment definition, hazards to spacecraft, and space object management. It concluded that orbital debris is a potential problem for future space operations. However, before recommending any major efforts to control the environment, more data are required. The most significant required data are on the population of debris smaller than 4 cm in diameter. New damage criteria are also required. When these data are obtained, they can be combined with hypervelocity data to evaluate the hazards to future spacecraft. After these hazards are understood, then techniques to control the environment can be evaluated.

  1. SPECS: Orbital debris removal

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The debris problem has reached a stage at which the risk to satellites and spacecraft has become substantial in low Earth orbit (LEO). This research discovered that small particles posed little threat to spacecraft because shielding can effectively prevent these particles from damaging the spacecraft. The research also showed that, even though collision with a large piece of debris could destroy the spacecraft, the large pieces of debris pose little danger because they can be tracked and the spacecraft can be maneuvered away from these pieces. Additionally, there are many current designs to capture and remove large debris particles from the space environment. From this analysis, it was decided to concentrate on the removal of medium-sized orbital debris, that is, those pieces ranging from 1 cm to 50 cm in size. The current design incorporates a transfer vehicle and a netting vehicle to capture the medium-sized debris. The system is based near an operational space station located at 28.5 deg inclination and 400 km altitude. The system uses ground-based tracking to determine the location of a satellite breakup or debris cloud. These data are uploaded to the transfer vehicle, which proceeds to rendezvous with the debris at a lower altitude parking orbit. Next, the netting vehicle is deployed, tracks the targeted debris, and captures it. After expending the available nets, the netting vehicle returns to the transfer vehicle for a new netting module and continues to capture more debris in the target area. Once all the netting modules are expended, the transfer vehicle returns to the space station's orbit where it is resupplied with new netting modules from a space shuttle load. The new modules are launched by the shuttle from the ground and the expended modules are taken back to Earth for removal of the captured debris, refueling, and repacking of the nets. Once the netting modules are refurbished, they are taken back into orbit for reuse. In a typical mission, the

  2. Reducing mode circulating fluid bed combustion

    DOEpatents

    Lin, Yung-Yi; Sadhukhan, Pasupati; Fraley, Lowell D.; Hsiao, Keh-Hsien

    1986-01-01

    A method for combustion of sulfur-containing fuel in a circulating fluid bed combustion system wherein the fuel is burned in a primary combustion zone under reducing conditions and sulfur captured as alkaline sulfide. The reducing gas formed is oxidized to combustion gas which is then separated from solids containing alkaline sulfide. The separated solids are then oxidized and recycled to the primary combustion zone.

  3. Sealpot and method for controlling a solids flow rate therethrough

    DOEpatents

    Chiu, John H.; Teigen, Bard C.

    2015-10-20

    A sealpot for a combustion power plant includes a downcomer standpipe which receives solids of the combustion power plant, a bed including a first end and a second opposite end, the first end connected to the downcomer standpipe, a discharge standpipe disposed at the second opposite end of the bed, and an orifice plate disposed between the bed and the discharge standpipe separating the discharge standpipe from the bed. The orifice plate includes apertures disposed at a height above the bed which allow transport of fluidized solids and gas through the orifice plate.

  4. Influence of woody debris on channel structure in old growth and managed forest streams in central Sweden.

    PubMed

    Dahlström, Niklas; Nilsson, Christer

    2004-03-01

    Anecdotal information suggests that woody debris have had an important channel-forming role in Swedish streams and rivers, but there are few data to support this view. We identified 10 streams within near-natural and 10 streams within managed forest landscapes in central Sweden, and quantified their channel characteristics and content of woody debris. All pieces of woody debris greater than 0.5 m in length and greater than 0.05 m in base diameter were included. The near-natural forests were situated in reserves protected from forest cutting, whereas the managed forests had previously faced intensive logging in the area adjacent to the stream. The two sets of streams did not differ in general abiotic characteristics such as width, slope, or boulder cover, but the number of wood pieces was twice as high and the wood volume almost four times as high in the near-natural streams. This difference resulted in a higher frequency of debris dams in the near-natural streams. Although the total pool area did not differ between the two sets of streams, the wood-formed pools were larger and deeper, and potentially ecologically more important than other pools. In contrast to what has been believed so far, woody debris can be a channel-forming agent also in steeper streams with boulder beds. In a stepwise multiple regression analysis, pool area was positively and most strongly related to the quantity of woody debris, whereas channel gradient and wood volume were negatively related. The frequency of debris dams increased with the number of pieces of woody debris, but was not affected by other variables. The management implications of this study are that the wood quantity in streams in managed forests would need to be increased if management of streams will target more pristine conditions.

  5. Internal dust recirculation system for a fluidized bed heat exchanger

    DOEpatents

    Gamble, Robert L.; Garcia-Mallol, Juan A.

    1981-01-01

    A fluidized bed heat exchanger in which air is passed through a bed of particulate material containing fuel disposed in a housing. A steam/water natural circulation system is provided in a heat exchange relation to the bed and includes a steam drum disposed adjacent the bed and a tube bank extending between the steam drum and a water drum. The tube bank is located in the path of the effluent gases exiting from the bed and a baffle system is provided to separate the solid particulate matter from the effluent gases. The particulate matter is collected and injected back into the fluidized bed.

  6. The simulation and experimental validation on gas-solid two phase flow in the riser of a dense fluidized bed

    NASA Astrophysics Data System (ADS)

    Wang, Xue-Yao; Jiang, Fan; Xu, Xiang; Wang, Sheng-Dian; Fan, Bao-Guo; Xiao, Yun-Han

    2009-06-01

    Gas-solid flow in dense CFB (circulating fluidized bed)) riser under the operating condition, superficial gas 15.5 m/s and solid flux 140 kg/m2s using Geldart B particles (sand) was investigated by experiments and CFD (computational fluid dynamics) simulation. The overall and local flow characteristics are determined using the axial pressure profiles and solid concentration profiles. The cold experimental results indicate that the axial solid concentration distribution contains a dilute region towards the up-middle zone and a dense region near the bottom and the top exit zones. The typical core-annulus structure and the back-mixing phenomenon near the wall of the riser can be observed. In addition, owing to the key role of the drag force of gas-solid phase, a revised drag force coefficient, based on the EMMS (energy-minimization multi-scale) model which can depict the heterogeneous character of gas-solid two phase flow, was proposed and coupled into the CFD control equations. In order to find an appropriate drag force model for the simulation of dense CFB riser, not only the revised drag force model but some other kinds of drag force model were used in the CFD. The flow structure, solid concentration, clusters phenomenon, fluctuation of two phases and axial pressure drop were analyzed. By comparing the experiment with the simulation, the results predicted by the EMMS drag model showed a better agreement with the experimental axial average pressure drop and apparent solid volume fraction, which proves that the revised drag force based on the EMMS model is an appropriate model for the dense CFB simulation.

  7. Woody debris

    Treesearch

    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...

  8. Turbomachinery debris remover

    DOEpatents

    Krawiec, Donald F.; Kraf, Robert J.; Houser, Robert J.

    1988-01-01

    An apparatus for removing debris from a turbomachine. The apparatus includes housing and remotely operable viewing and grappling mechanisms for the purpose of locating and removing debris lodged between adjacent blades in a turbomachine.

  9. Wholesale debris removal from LEO

    NASA Astrophysics Data System (ADS)

    Levin, Eugene; Pearson, Jerome; Carroll, Joseph

    2012-04-01

    Recent advances in electrodynamic propulsion make it possible to seriously consider wholesale removal of large debris from LEO for the first time since the beginning of the space era. Cumulative ranking of large groups of the LEO debris population and general limitations of passive drag devices and rocket-based removal systems are analyzed. A candidate electrodynamic debris removal system is discussed that can affordably remove all debris objects over 2 kg from LEO in 7 years. That means removing more than 99% of the collision-generated debris potential in LEO. Removal is performed by a dozen 100-kg propellantless vehicles that react against the Earth's magnetic field. The debris objects are dragged down and released into short-lived orbits below ISS. As an alternative to deorbit, some of them can be collected for storage and possible in-orbit recycling. The estimated cost per kilogram of debris removed is a small fraction of typical launch costs per kilogram. These rates are low enough to open commercial opportunities and create a governing framework for wholesale removal of large debris objects from LEO.

  10. Space Debris Modeling at NASA

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2001-01-01

    Since the Second European Conference on Space Debris in 1997, the Orbital Debris Program Office at the NASA Johnson Space Center has undertaken a major effort to update and improve the principal software tools employed to model the space debris environment and to evaluate mission risks. NASA's orbital debris engineering model, ORDEM, represents the current and near-term Earth orbital debris population from the largest spacecraft to the smallest debris in a manner which permits spacecraft engineers and experimenters to estimate the frequency and velocity with which a satellite may be struck by debris of different sizes. Using expanded databases and a new program design, ORDEM2000 provides a more accurate environment definition combined with a much broader array of output products in comparison with its predecessor, ORDEM96. Studies of the potential long-term space debris environment are now conducted with EVOLVE 4.0, which incorporates significant advances in debris characterization and breakup modeling. An adjunct to EVOLVE 4.0, GEO EVOLVE has been created to examine debris issues near the geosynchronous orbital regime. In support of NASA Safety Standard 1740.14, which establishes debris mitigation guidelines for all NASA space programs, a set of evaluation tools called the Debris Assessment Software (DAS) is specifically designed for program offices to determine whether they are in compliance with NASA debris mitigation guidelines. DAS 1.5 has recently been released with improved WINDOWS compatibility and graphics functions. DAS 2.0 will incorporate guideline changes in a forthcoming revision to NASA Safety Standard 1740.14. Whereas DAS contains a simplified model to calculate possible risks associated with satellite reentries, NASA's higher fidelity Object Reentry Survival Analysis Tool (ORSAT) has been upgraded to Version 5.0. With the growing awareness of the potential risks posed by uncontrolled satellite reentries to people and property on Earth, the

  11. Techniques for debris control

    NASA Technical Reports Server (NTRS)

    Petro, Andrew J.

    1990-01-01

    This paper will summarize a range of techniques which have been proposed for controlling the growth of man-made debris in earth orbit. Several techniques developed in studies at the Johnson Space Center will be described in detail. These techniques include the retrieval of inoperative satellites with an orbital maneuvering vehicle and self-disposal devices for satellites and upper stages. Self-disposal devices include propulsive deorbit motors and passive drag-augmentation devices. Concepts for sweeping small debris from the orbital environment will also be described. An evaluation of the technical feasibility and economic practicality of the various control methods will be summarized. In general, methods which prevent the accumulation of large debris objects were found to provide greater promise for control of the debris problem than methods of removing small debris particles.

  12. Diesel NO{sub x} reduction by plasma-regenerated absorbent beds

    DOEpatents

    Wallman, P.H.; Vogtlin, G.E.

    1998-02-10

    Reduction of NO{sub x} from diesel engine exhaust by use of plasma-regenerated absorbent beds is described. This involves a process for the reduction of NO{sub x} and particulates from diesel engines by first absorbing NO{sub x} onto a solid absorbent bed that simultaneously acts as a physical trap for the particulate matter, and second regenerating said solid absorbent by pulsed plasma decomposition of absorbed NO{sub x} followed by air oxidation of trapped particulate matter. The absorbent bed may utilize all metal oxides, but the capacity and the kinetics of absorption and desorption vary between different materials, and thus the composition of the absorbent bed is preferably a material which enables the combination of NO{sub x} absorption capability with catalytic activity for oxidation of hydrocarbons. Thus, naturally occurring or synthetically prepared materials may be utilized, particularly those having NO{sub x} absorption properties up to temperatures around 400 C which is in the area of diesel engine exhaust temperatures. 1 fig.

  13. Diesel NO.sub.x reduction by plasma-regenerated absorbend beds

    DOEpatents

    Wallman, P. Henrik; Vogtlin, George E.

    1998-01-01

    Reduction of NO.sub.x from diesel engine exhaust by use of plasma-regenerated absorbent beds. This involves a process for the reduction of NO.sub.x and particulates from diesel engines by first absorbing NO.sub.x onto a solid absorbent bed that simultaneously acts as a physical trap for the particulate matter, and second regenerating said solid absorbent by pulsed plasma decomposition of absorbed NO.sub.x followed by air oxidation of trapped particulate matter. The absorbent bed may utilize all metal oxides, but the capacity and the kinetics of absorption and desorption vary between different materials, and thus the composition of the absorbent bed is preferably a material which enables the combination of NO.sub.x absorption capability with catalytic activity for oxidation of hydrocarbons. Thus, naturally occurring or synthetically prepared materials may be utilized, particularly those having NO.sub.x absorption properties up to temperatures around 400.degree. C. which is in the area of diesel engine exhaust temperatures.

  14. Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass

    NASA Astrophysics Data System (ADS)

    Fotovat, Farzam

    This thesis focuses on the characterization of hydrodynamics and mixing phenomena in fluidized beds containing mixtures of sand and irregular biomass particles. The first objective of this study is understanding the effect of the large biomass particles on the bubbling characteristics and gas distribution pattern of sand fluidized beds. The second objective is the characterization of mixing/segregation of biomass and sand particles under fluidization conditions. A variety of experimental techniques are employed to study the behavior of two constituting phases of a fluidized bed, i.e., dilute (bubble) and dense (emulsion) phases. Exploring the characteristic fluidization velocities of sand-biomass mixtures unveils that the onset of bubbling in these systems occurs at a higher gas velocity compared to that of the initial fluidization velocity (Uif). The initial bubbling velocity (Uib), the final fluidization velocity ( Uff), and the transition gas velocity from bubbling to turbulent regime (Uc) rise by increasing the fraction of biomass in the mixture. Statistical analysis of the pressure signal at top of the bed reveals that increasing the biomass load hinders the evolution of bubbles at a low gas velocity (U<0.6 m/s), while at high velocities, the bubbling trend of beds containing different fractions of biomass is comparable. The addition of biomass particles to a bed of sand leads to an increase in the mean voidage of the bed; however, the voidage of each phase remains unaffected. It is observed that large biomass particles trigger a break-up of the bubbles, which results in boosting bubbling frequency. The fraction of bubbles at the center of the bed increases with the load of biomass. At the wall region, however, it starts to decrease by adding 2% wt. biomass to pure sand and then increases with the further addition of biomass. The Radioactive Particle Tracking (RPT) technique is implemented in the second section of this work to study the motion and distribution

  15. Numerical simulation of failure behavior of granular debris flows based on flume model tests.

    PubMed

    Zhou, Jian; Li, Ye-xun; Jia, Min-cai; Li, Cui-na

    2013-01-01

    In this study, the failure behaviors of debris flows were studied by flume model tests with artificial rainfall and numerical simulations (PFC(3D)). Model tests revealed that grain sizes distribution had profound effects on failure mode, and the failure in slope of medium sand started with cracks at crest and took the form of retrogressive toe sliding failure. With the increase of fine particles in soil, the failure mode of the slopes changed to fluidized flow. The discrete element method PFC(3D) can overcome the hypothesis of the traditional continuous medium mechanic and consider the simple characteristics of particle. Thus, a numerical simulations model considering liquid-solid coupled method has been developed to simulate the debris flow. Comparing the experimental results, the numerical simulation result indicated that the failure mode of the failure of medium sand slope was retrogressive toe sliding, and the failure of fine sand slope was fluidized sliding. The simulation result is consistent with the model test and theoretical analysis, and grain sizes distribution caused different failure behavior of granular debris flows. This research should be a guide to explore the theory of debris flow and to improve the prevention and reduction of debris flow.

  16. Bed material agglomeration during fluidized bed combustion. Final report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brown, R.C.; Dawson, M.R.; Smeenk, J.L.

    The purpose of this project is to determine the physical and chemical reactions which lead to the undesired agglomeration of bed material during fluidized bed combustion of coal and to relate these reactions to specific causes. A survey of agglomeration and deposit formation in industrial fluidized bed combustors (FBCs) indicate that at least five boilers were experiencing some form of bed material agglomeration. Deposit formation was reported at nine sites with deposits most commonly at coal feed locations and in cyclones. Other deposit locations included side walls and return loops. Three general types of mineralogic reactions were observed to occurmore » in the agglomerates and deposits. Although alkalies may play a role with some {open_quotes}high alkali{close_quotes} lignites, we found agglomeration was initiated due to fluxing reactions between iron (II) from pyrites and aluminosilicates from clays. This is indicated by the high amounts of iron, silica, and alumina in the agglomerates and the mineralogy of the agglomerates. Agglomeration likely originated in the dense phase of the FBC bed within the volatile plume which forms when coal is introduced to the boiler. Secondary mineral reactions appear to occur after the agglomerates have formed and tend to strengthen the agglomerates. When calcium is present in high amounts, most of the minerals in the resulting deposits are in the melilite group (gehlenite, melilite, and akermanite) and pyroxene group (diopside and augite). During these solid-phase reactions, the temperature of formation of the melilite minerals can be lowered by a reduction of the partial pressure of CO{sub 2} (Diopside + Calcite {r_arrow}Akermanite).« less

  17. Modeling the space debris environment with MASTER-2009 and ORDEM2010

    NASA Astrophysics Data System (ADS)

    Flegel, Sven Kevin; Krisko, Paula; Gelhaus, Johannes; Wiedemann, Carsten; Moeckel, Marek; Krag, Holger; Klinkrad, Heiner; Xu, Yu-Lin; Horstman, Matthew; Matney, Mark; Vörsmann, Peter

    The two software tools MASTER-2009 and ORDEM2010 are the ESA and NASA reference software tools respectively which describe the earth's debris environment. The primary goal of both programs is to allow users to estimate the object flux onto a target object for mission planning. The current paper describes the basic distinctions in the model philosophies. At the core of each model lies the method by which the object environment is established. Cen-tral to this process is the role played by the results from radar/telescope observations or impact fluxes on surfaces returned from earth orbit. The ESA Meteoroid and Space Debris Terrestrial Environment Reference Model (MASTER) is engineered to give a realistic description of the natural and the man-made particulate environment of the earth. Debris sources are simulated based on detailed lists of known historical events such as fragmentations or solid rocket motor firings or through simulation of secondary debris such as impact ejecta or the release of paint flakes from degrading spacecraft surfaces. The resulting population is then validated against historical telescope/radar campaigns using the ESA Program for Radar and Optical Observa-tion Forecasting (PROOF) and against object impact fluxes on surfaces returned from space. The NASA Orbital Debris Engineering Model (ORDEM) series is designed to provide reliable estimates of orbital debris flux on spacecraft and through telescope or radar fields-of-view. Central to the model series is the empirical nature of the input populations. These are derived from NASA orbital debris modeling but verified, where possible, with measurement data from various sources. The latest version of the series, ORDEM2010, compiles over two decades of data from NASA radar systems, telescopes, in-situ sources, and ground tests that are analyzed by statistical methods. For increased understanding of the application ranges of the two programs, the current paper provides an overview of the two

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

    USGS Publications Warehouse

    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.

  19. Pyrolysis reactor and fluidized bed combustion chamber

    DOEpatents

    Green, Norman W.

    1981-01-06

    A solid carbonaceous material is pyrolyzed in a descending flow pyrolysis reactor in the presence of a particulate source of heat to yield a particulate carbon containing solid residue. The particulate source of heat is obtained by educting with a gaseous source of oxygen the particulate carbon containing solid residue from a fluidized bed into a first combustion zone coupled to a second combustion zone. A source of oxygen is introduced into the second combustion zone to oxidize carbon monoxide formed in the first combustion zone to heat the solid residue to the temperature of the particulate source of heat.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Space Debris & its Mitigation

    NASA Astrophysics Data System (ADS)

    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

  2. Simulation of fluidized bed coal combustors

    NASA Technical Reports Server (NTRS)

    Rajan, R.

    1979-01-01

    The many deficiencies of previous work on simulation of fluidized bed combustion (FBC) processes are presented. An attempt is made to reduce these deficiencies, and to formulate a comprehensive FBC model taking into account the following elements: (1) devolatilization of coal and the subsequent combustion of volatiles and residual char; (2) sulfur dioxide capture by limestone; (3) NOx release and reduction of NOx by char; (4) attrition and elutriation of char and limestone; (5) bubble hydrodynamics; (6) solids mixing; (7) heat transfer between gas and solid, and solid and heat exchange surfaces; and (8) freeboard reactions.

  3. Kinetic vaporization of heavy metals during fluidized bed thermal treatment of municipal solid waste.

    PubMed

    Yu, Jie; Sun, Lushi; Xiang, Jun; Hu, Song; Su, Sheng

    2013-02-01

    Heavy metals volatilization during thermal treatment of model solid waste was theoretically and experimentally investigated in a fluidized bed reactor. Lead, cadmium, zinc and copper, the most four conventional heavy metals were investigated. Particle temperature model and metal diffusion model were established to simulate the volatilization of CdCl(2) evaporation and investigate the possible influencing factors. The diffusion coefficient, porosity and particle size had significant effects on metal volatilization. The higher diffusion coefficient and porosity resulted in the higher metal evaporation. The influence of redox conditions, HCl, water and mineral matrice were also investigated experimentally. The metal volatilization can be promoted by the injection of HCl, while oxygen played a negative role. The diffusion process of heavy metals within particles also had a significant influence on kinetics of their vaporization. The interaction between heavy metals and mineral matter can decrease metal evaporation amount by forming stable metallic species. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. JSC Orbital Debris Website Description

    NASA Technical Reports Server (NTRS)

    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

  5. Bi-objective optimization of a multiple-target active debris removal mission

    NASA Astrophysics Data System (ADS)

    Bérend, Nicolas; Olive, Xavier

    2016-05-01

    The increasing number of space debris in Low-Earth Orbit (LEO) raises the question of future Active Debris Removal (ADR) operations. Typical ADR scenarios rely on an Orbital Transfer Vehicle (OTV) using one of the two following disposal strategies: the first one consists in attaching a deorbiting kit, such as a solid rocket booster, to the debris after rendezvous; with the second one, the OTV captures the debris and moves it to a low-perigee disposal orbit. For multiple-target ADR scenarios, the design of such a mission is very complex, as it involves two optimization levels: one for the space debris sequence, and a second one for the "elementary" orbit transfer strategy from a released debris to the next one in the sequence. This problem can be seen as a Time-Dependant Traveling Salesman Problem (TDTSP) with two objective functions to minimize: the total mission duration and the total propellant consumption. In order to efficiently solve this problem, ONERA has designed, under CNES contract, TOPAS (Tool for Optimal Planning of ADR Sequence), a tool that implements a Branch & Bound method developed in previous work together with a dedicated algorithm for optimizing the "elementary" orbit transfer. A single run of this tool yields an estimation of the Pareto front of the problem, which exhibits the trade-off between mission duration and propellant consumption. We first detail our solution to cope with the combinatorial explosion of complex ADR scenarios with 10 debris. The key point of this approach is to define the orbit transfer strategy through a small set of parameters, allowing an acceptable compromise between the quality of the optimum solution and the calculation cost. Then we present optimization results obtained for various 10 debris removal scenarios involving a 15-ton OTV, using either the deorbiting kit or the disposal orbit strategy. We show that the advantage of one strategy upon the other depends on the propellant margin, the maximum duration allowed

  6. Development of carvedilol-cyclodextrin inclusion complexes using fluid-bed granulation: a novel solid-state complexation alternative with technological advantages.

    PubMed

    Alonso, Ellen C P; Riccomini, Karina; Silva, Luis Antônio D; Galter, Daniela; Lima, Eliana M; Durig, Thomas; Taveira, Stephania F; Martins, Felipe Terra; Cunha-Filho, Marcílio S S; Marreto, Ricardo N

    2016-10-01

    This study sought to evaluate the achievement of carvedilol (CARV) inclusion complexes with modified cyclodextrins (HPβCD and HPγCD) using fluid-bed granulation (FB). The solid complexes were produced using FB and spray drying (SD) and were characterised by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction, SEM, flowability and particle size analyses and in vitro dissolution. The DSC, FTIR and powder X-ray diffraction findings suggested successful CARV inclusion in the modified β- and γ-cyclodextrins, which was more evident in acidic media. The CARV dissolution rate was ~7-fold higher for complexes with both cyclodextrins prepared using SD than for raw CARV. Complexes prepared with HPβCD using FB also resulted in a significant improvement in dissolution rate (~5-fold) and presented superior flowability and larger particle size. The findings suggested that FB is the best alternative for large-scale production of solid dosage forms containing CARV. Additionally, the results suggest that HPγCD could be considered as another option for CARV complexation because of its excellent performance in inclusion complex formation in the solid state. © 2016 Royal Pharmaceutical Society.

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

    NASA Technical Reports Server (NTRS)

    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.

  8. 44 CFR 206.224 - Debris removal.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 44 Emergency Management and Assistance 1 2011-10-01 2011-10-01 false Debris removal. 206.224... Debris removal. (a) Public interest. Upon determination that debris removal is in the public interest, the Regional Administrator may provide assistance for the removal of debris and wreckage from publicly...

  9. 44 CFR 206.224 - Debris removal.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 44 Emergency Management and Assistance 1 2013-10-01 2013-10-01 false Debris removal. 206.224... Debris removal. (a) Public interest. Upon determination that debris removal is in the public interest, the Regional Administrator may provide assistance for the removal of debris and wreckage from publicly...

  10. 44 CFR 206.224 - Debris removal.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 44 Emergency Management and Assistance 1 2012-10-01 2011-10-01 true Debris removal. 206.224... Debris removal. (a) Public interest. Upon determination that debris removal is in the public interest, the Regional Administrator may provide assistance for the removal of debris and wreckage from publicly...

  11. 44 CFR 206.224 - Debris removal.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Debris removal. 206.224... Debris removal. (a) Public interest. Upon determination that debris removal is in the public interest, the Regional Administrator may provide assistance for the removal of debris and wreckage from publicly...

  12. 44 CFR 206.224 - Debris removal.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 44 Emergency Management and Assistance 1 2014-10-01 2014-10-01 false Debris removal. 206.224... Debris removal. (a) Public interest. Upon determination that debris removal is in the public interest, the Regional Administrator may provide assistance for the removal of debris and wreckage from publicly...

  13. Distribution, recruitment, and geomorphic significance of large woody debris in an alluvial forest stream: Tonghi Creek, southeastern Australia

    NASA Astrophysics Data System (ADS)

    Webb, Ashley A.; Erskine, Wayne D.

    2003-03-01

    The complex yet poorly understood interactions between riparian vegetation, large woody debris and fluvial geomorphology in an anthropogenically undisturbed reach of an alluvial, sand-bed forest stream in SE Australia have been determined. Riparian vegetation exhibits lateral and vertical zonation of understorey and overstorey species. The dominant riparian tree species, Tristaniopsis laurina (water gum), grows within the channel and on the floodplain within one channel width of the stream. Larger Eucalyptus species only grow on the highest parts of the floodplain and on a low Pleistocene river terrace. A complete large woody debris (LWD) census conducted in the 715-m-long study reach revealed that water gum comprises 17.6% of the total LWD loading, which, at 576 m 3 ha -1, is high for a stream with a catchment area of 187 km 2. Although most LWD has a small diameter (0.1-0.3 m), the greatest contribution to the total volume of LWD is by pieces with a diameter between 0.3 and 0.7 m. A high proportion of LWD (10.4%) has a blockage ratio greater than 10%. The spatial distribution of LWD is random both longitudinally and within individual meander bends. Dominant recruitment processes of LWD vary by species. T. laurina trees are recruited to the channel by minor bank erosion and senescence, while the Eucalyptus species are predominantly recruited from the highest parts of the floodplain/low-river terrace by episodic windthrow during large storms. Multiple radiocarbon dates of outer wood of immobile LWD indicate a maximum residence time of 240±40 years BP for T. laurina timber. The high loading of LWD combined with the extensive root systems of riparian vegetation stabilize Tonghi Creek. Log steps form natural wooden drop-structures with a mean height of 29 mm that were responsible for 20.5% of the total head loss under base flow conditions ( Q=0.08 m 3 s -1). Large woody debris is buried in the bed at depths of up to 2.3 m and is responsible for an estimated 49% of

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Spatial-temporal analysis of marine debris on beaches of Niterói, RJ, Brazil: Itaipu and Itacoatiara.

    PubMed

    Silva, Melanie Lopes da; Araújo, Fábio Vieira de; Castro, Rebeca Oliveira; Sales, Alessandro Souza

    2015-03-15

    In many areas of the world, studies of marine debris are conducted with an emphasis on analyzing their composition, quantification and distribution on sandy beaches. However, in Brazil, studies are still restricted to some areas of the coast, and the quantities and the spatial and temporal patterns are unknown. To enhance the marine debris information in these areas, we selected the Itaipu and Itacoatiara beaches in Niterói, RJ, to collect, quantify and qualify the solid residues present in their sands. We collected 12 samples and recorded 118.39 kg of residues in Itaipu and 62.94 kg in Itacoatiara. At both beaches, the largest portion of debris was located on the upper part of the beach. Several debris items were related to food and drink consumption on the beaches, which indicated the contribution of beach users to pollution. Most of the debris was plastic. The greatest amount of debris was found at Itaipu in January and February and at Itacoatiara in January and March, months related to both the holiday season and abundant rainfall. The results demonstrated the necessity to implement an Environmental Education project for these areas to reduce its degradation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Geomorphic change caused by outburst floods and debris flows at Mount Rainier, Washington, with emphasis on Tahoma Creek valley

    USGS Publications Warehouse

    Walder, J.S.; Driedger, C.L.

    1994-01-01

    Debris flows have caused rapid geomorphic change in several glacierized drainages on Mount Rainier, Washington. Nearly all of these flows began as glacial outburst floods, then transformed to debris flows by incorporating large masses of sediment in channel reaches where streams have incised proglacial sediments and stagnant glacier ice. This stagnant ice is a relic of advanced glacier positions achieved during the mid-nineteenth century Little Ice Age maximum and the readvance of the 1960's and 1970's. Debris flows have been especially important agents of geomorphic change along Tahoma Creek, which drains South Tahoma Glacier. Debris flows in Tahoma Creek valley have transported downstream about 107 m3 Of sediment since 1967, causing substantial aggradation and damage to roads and facilities in Mount Rainier National Park. The average denudation rate in the upper part of the Tahoma Creek drainage basin in the same period has been extraordinarily high: more than 20 millimeters per year, a value exceeded only rarely in basins affected by debris flows. However, little or none of this sediment has yet passed out of the Tahoma Creek drainage basin. Outburst floods from South Tahoma Glacier form by release of subglacially stored water. The volume of stored water discharged during a typical outburst flood would form a layer several tens of millimeters thick over the bed of the entire glacier, though it is more likely that large linked cavities account for most of the storage. Statistical analysis shows that outburst floods usually occur during periods of atypically hot or rainy weather in summer or early autumn, and that the probability of an outburst increases with temperature (a proxy measure of ablation rate) or rainfall rate. On the basis of these results, we suggest that outburst floods are triggered when rapid input of water to the glacier bed causes transient increase in water pressure, thereby destabilizing the linked-cavity system. The probabilistic nature of

  18. Exploiting Orbital Data and Observation Campaigns to Improve Space Debris Models

    NASA Astrophysics Data System (ADS)

    Braun, V.; Horstmann, A.; Reihs, B.; Lemmens, S.; Merz, K.; Krag, H.

    The European Space Agency (ESA) has been developing the Meteoroid and Space Debris Terrestrial Environment Reference (MASTER) software as the European reference model for space debris for more than 25 years. It is an event-based simulation of all known individual debris-generating events since 1957, including breakups, solid rocket motor firings and nuclear reactor core ejections. In 2014, the upgraded Debris Risk Assessment and Mitigation Analysis (DRAMA) tool suite was released. In the same year an ESA instruction made the standard ISO 24113:2011 on space debris mitigation requirements, adopted via the European Cooperation for Space Standardization (ECSS), applicable to all ESA missions. In order to verify the compliance of a space mission with those requirements, the DRAMA software is used to assess collision avoidance statistics, estimate the remaining orbital lifetime and evaluate the on-ground risk for controlled and uncontrolled reentries. In this paper, the approach to validate the MASTER and DRAMA tools is outlined. For objects larger than 1 cm, thus potentially being observable from ground, the MASTER model has been validated through dedicated observation campaigns. Recent campaign results shall be discussed. Moreover, catalogue data from the Space Surveillance Network (SSN) has been used to correlate the larger objects. In DRAMA, the assessment of collision avoidance statistics is based on orbit uncertainty information derived from Conjunction Data Messages (CDM) provided by the Joint Space Operations Center (JSpOC). They were collected for more than 20 ESA spacecraft in the recent years. The way this information is going to be used in a future DRAMA version is outlined and the comparison of estimated manoeuvre rates with real manoeuvres from the operations of ESA spacecraft is shown.

  19. Assessment of different bedding systems for lactating cows in freestall housing

    USDA-ARS?s Scientific Manuscript database

    The objective of this study was to compare different bedding systems for lactating cows in freestall housing. Bedding systems included new sand (NS), recycled byproducts of manure separation (organic solids [OS] and recycled sand [RS]), and foam-core mattresses with a shallow layer of OS (MS). The e...

  20. Anthropogenic debris in seafood: Plastic debris and fibers from textiles in fish and bivalves sold for human consumption

    PubMed Central

    Rochman, Chelsea M.; Tahir, Akbar; Williams, Susan L.; Baxa, Dolores V.; Lam, Rosalyn; Miller, Jeffrey T.; Teh, Foo-Ching; Werorilangi, Shinta; Teh, Swee J.

    2015-01-01

    The ubiquity of anthropogenic debris in hundreds of species of wildlife and the toxicity of chemicals associated with it has begun to raise concerns regarding the presence of anthropogenic debris in seafood. We assessed the presence of anthropogenic debris in fishes and shellfish on sale for human consumption. We sampled from markets in Makassar, Indonesia, and from California, USA. All fish and shellfish were identified to species where possible. Anthropogenic debris was extracted from the digestive tracts of fish and whole shellfish using a 10% KOH solution and quantified under a dissecting microscope. In Indonesia, anthropogenic debris was found in 28% of individual fish and in 55% of all species. Similarly, in the USA, anthropogenic debris was found in 25% of individual fish and in 67% of all species. Anthropogenic debris was also found in 33% of individual shellfish sampled. All of the anthropogenic debris recovered from fish in Indonesia was plastic, whereas anthropogenic debris recovered from fish in the USA was primarily fibers. Variations in debris types likely reflect different sources and waste management strategies between countries. We report some of the first findings of plastic debris in fishes directly sold for human consumption raising concerns regarding human health. PMID:26399762

  1. Current Issues in Orbital Debris

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2011-01-01

    During the past two decades, great strides have been made in the international community regarding orbital debris mitigation. The majority of space-faring nations have reached a consensus on an initial set of orbital debris mitigation measures. Implementation of and compliance with the IADC and UN space debris mitigation guidelines should remain a high priority. Improvements of the IADC and UN space debris mitigation guidelines should continue as technical consensus permits. The remediation of the near-Earth space environment will require a significant and long-term undertaking.

  2. SOLID PHASE MICROEXTRACTION SAMPLING OF FIRE DEBRIS RESIDUES IN THE PRESENCE OF RADIONUCLIDE SURROGATE METALS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Duff, M; Keisha Martin, K; S Crump, S

    2007-03-23

    The Federal Bureau of Investigation (FBI) Laboratory currently does not have on site facilities for handling radioactive evidentiary materials and there are no established FBI methods or procedures for decontaminating highly radioactive fire debris (FD) evidence while maintaining evidentiary value. One experimental method for the isolation of FD residue from radionuclide metals involves using solid phase microextraction (SPME) fibers to remove the residues of interest. Due to their high affinity for organics, SPME fibers should have little affinity for most (radioactive) metals. The focus of this research was to develop an examination protocol that was applicable to safe work inmore » facilities where high radiation doses are shielded from the workers (as in radioactive shielded cells or ''hot cells''). We also examined the affinity of stable radionuclide surrogate metals (Co, Ir, Re, Ni, Ba, Cs, Nb, Zr and Nd) for sorption by the SPME fibers. This was done under exposure conditions that favor the uptake of FD residues under conditions that will provide little contact between the SPME and the FD material (such as charred carpet or wood that contains commonly-used accelerants). Our results from mass spectrometric analyses indicate that SPME fibers show promise for use in the room temperature head space uptake of organic FD residue (namely, diesel fuel oil, kerosene, gasoline and paint thinner) with subsequent analysis by gas chromatography (GC) with mass spectrometric (MS) detection. No inorganic forms of ignitable fluids were included in this study.« less

  3. Activities on space debris in Europe

    NASA Astrophysics Data System (ADS)

    Flury, W.

    2001-10-01

    Activities on space debris in Europe are carried out by ESA, by national space agencies such as ASI (Italy), BNSC (United Kingdom), CNES (France) and DLR (Germany) and by various research groups. The objectives of ESA's activities in the field of space debris have been defined by the Council of ESA in 1989, and were updated in 2000 with the adoption of the Resolution for a European policy on the protection of the space environment from debris. ESA's debris-related activities comprise research, application of debris mitigation measures and international cooperation. The research activities address the knowledge of the terrestrial particulate environment, risk assessment, hypervelocity impacts and protection, and preventative measures. In all these areas substantial progress has been achieved. Examples are the MASTER 99 model, the DISCOS database, beam-park experiments with the FGAN radar, the discovery of a small-size debris population in GEO with the Space Debris telescope at the Teide observatory, and the GORID dust detector in the geostationary orbit. The ESA Space Debris Mitigation Handbook was issued, and in a joint effort of ESA and the national agencies ASI, BNSC, CNES and DLR the European Space Debris Safety and Mitigation Standard (draft) was established. This standard will be harmonized with standards of other agencies through the deliberations in the Inter-Agency Space Debris Coordination Committee (IADC). In order to strengthen the European cooperation, the pilot network of centers - Working Group on Space Debris was created in 2000. The members are ESA, ASI, BNSC, CNES and DLR. An integrated work plan has been established for the period 2001-2003. Global cooperation among the space-faring nations is achieved through the IADC. ESA and its Member States strongly support the deliberations on space debris within the United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOS).

  4. A finite volume solver for three dimensional debris flow simulations based on a single calibration parameter

    NASA Astrophysics Data System (ADS)

    von Boetticher, Albrecht; Turowski, Jens M.; McArdell, Brian; Rickenmann, Dieter

    2016-04-01

    Debris flows are frequent natural hazards that cause massive damage. A wide range of debris flow models try to cover the complex flow behavior that arises from the inhomogeneous material mixture of water with clay, silt, sand, and gravel. The energy dissipation between moving grains depends on grain collisions and tangential friction, and the viscosity of the interstitial fine material suspension depends on the shear gradient. Thus a rheology description needs to be sensitive to the local pressure and shear rate, making the three-dimensional flow structure a key issue for flows in complex terrain. Furthermore, the momentum exchange between the granular and fluid phases should account for the presence of larger particles. We model the fine material suspension with a Herschel-Bulkley rheology law, and represent the gravel with the Coulomb-viscoplastic rheology of Domnik & Pudasaini (Domnik et al. 2013). Both composites are described by two phases that can mix; a third phase accounting for the air is kept separate to account for the free surface. The fluid dynamics are solved in three dimensions using the finite volume open-source code OpenFOAM. Computational costs are kept reasonable by using the Volume of Fluid method to solve only one phase-averaged system of Navier-Stokes equations. The Herschel-Bulkley parameters are modeled as a function of water content, volumetric solid concentration of the mixture, clay content and its mineral composition (Coussot et al. 1989, Yu et al. 2013). The gravel phase properties needed for the Coulomb-viscoplastic rheology are defined by the angle of repose of the gravel. In addition to this basic setup, larger grains and the corresponding grain collisions can be introduced by a coupled Lagrangian particle simulation. Based on the local Savage number a diffusive term in the gravel phase can activate phase separation. The resulting model can reproduce the sensitivity of the debris flow to water content and channel bed roughness, as

  5. Mathematical modeling of Kluyveromyces marxianus growth in solid-state fermentation using a packed-bed bioreactor.

    PubMed

    Mazutti, Marcio A; Zabot, Giovani; Boni, Gabriela; Skovronski, Aline; de Oliveira, Débora; Di Luccio, Marco; Rodrigues, Maria Isabel; Maugeri, Francisco; Treichel, Helen

    2010-04-01

    This work investigated the growth of Kluyveromyces marxianus NRRL Y-7571 in solid-state fermentation in a medium composed of sugarcane bagasse, molasses, corn steep liquor and soybean meal within a packed-bed bioreactor. Seven experimental runs were carried out to evaluate the effects of flow rate and inlet air temperature on the following microbial rates: cell mass production, total reducing sugar and oxygen consumption, carbon dioxide and ethanol production, metabolic heat and water generation. A mathematical model based on an artificial neural network was developed to predict the above-mentioned microbial rates as a function of the fermentation time, initial total reducing sugar concentration, inlet and outlet air temperatures. The results showed that the microbial rates were temperature dependent for the range 27-50 degrees C. The proposed model efficiently predicted the microbial rates, indicating that the neural network approach could be used to simulate the microbial growth in SSF.

  6. Temporal and spatial variability in thalweg profiles of a gravel-bed river

    USGS Publications Warehouse

    Madej, Mary Ann

    1999-01-01

    This study used successive longitudinal thalweg profiles in gravel-bed rivers to monitor changes in bed topography following floods and associated large sediment inputs. Variations in channel bed elevations, distributions of residual water depths, percentage of channel length occupied by riffles, and a spatial autocorrelation coefficient (Moran's I) were used to quantify changes in morphological diversity and spatial structure in Redwood Creek basin, northwestern California. Bed topography in Redwood Creek and its major tributaries consists primarily of a series of pools and riffles. The size, frequency and spatial distribution of the pools and riffles have changed significantly during the past 20 years. Following large floods and high sediment input in Redwood Creek and its tributaries in 1975, variation in channel bed elevations was low and the percentage of the channel length occupied by riffles was high. Over the next 20 years, variation in bed elevations increased while the length of channel occupied by riffles decreased. An index [(standard deviation of residual water depth/bankfull depth) × 100] was developed to compare variations in bed elevation over a range of stream sizes, with a higher index being indicative of greater morphological diversity. Spatial autocorrelation in the bed elevation data was apparent at both fine and coarse scales in many of the thalweg profiles and the observed spatial pattern of bed elevations was found to be related to the dominant channel material and the time since disturbance. River reaches in which forced pools dominated, and in which large woody debris and bed particles could not be easily mobilized, exhibited a random distribution of bed elevations. In contrast, in reaches where alternate bars dominated, and both wood and gravel were readily transported, regularly spaced bed topography developed at a spacing that increased with time since disturbance. This pattern of regularly spaced bed features was reversed

  7. Orbiting space debris: Dangers, measurement and mitigation

    NASA Astrophysics Data System (ADS)

    McNutt, Ross T.

    1992-06-01

    Space debris is a growing environmental problem. Accumulation of objects in earth orbit threatens space systems through the possibility of collisions and runaway debris multiplication. The amount of debris in orbit is uncertain due to the lack of information on the population of debris between 1 and 10 centimeters diameter. Collisions with debris even smaller than 1 cm can be catastrophic due to the high orbital velocities involved. Research efforts are under way at NASA, United States Space Command and the Air Force Phillips Laboratory to detect and catalog the debris population in near-earth space. Current international and national laws are inadequate to control the proliferation of space debris. Space debris is a serious problem with large economic, military, technical and diplomatic components. Actions need to be taken now to: determine the full extent of the orbital debris problem; accurately predict the future evolution of the debris population; decide the extent of the debris mitigation procedures required; implement these policies on a global basis via an international treaty. Action must be initiated now, before the loss of critical space systems such as the space shuttle or the space station.

  8. Orbiting space debris: Dangers, measurement, and mitigation

    NASA Astrophysics Data System (ADS)

    McNutt, Ross T.

    1992-01-01

    Space debris is a growing environmental problem. Accumulation of objects in Earth orbit threatens space systems through the possibility of collisions and runaway debris multiplication. The amount of debris in orbit is uncertain due to the lack of information on the population of debris between 1 and 10 centimeters diameter. Collisions with debris even smaller than 1 cm can be catastrophic due to the high orbital velocities involved. Research efforts are under way at NASA, Unites States Space Command and the Air Force Phillips Laboratory to detect and catalog the debris population in near-Earth space. Current international and national laws are inadequate to control the proliferation of space debris. Space debris is a serious problem with large economic, military, technical, and diplomatic components. Actions need to be taken now for the following reasons: determine the full extent of the orbital debris problem; accurately predict the future evolution of the debris population; decide the extent of the debris mitigation procedures required; implement these policies on a global basis via an international treaty. Action must be initiated now, before the the loss of critical space systems such as the Space Shuttle or the Space Station.

  9. Thermophysical Properties of Terrestrial Rock and Debris-covered Glaciers as Analogs for Martian Lobate Debris Aprons

    NASA Astrophysics Data System (ADS)

    Piatek, J. L.

    2009-03-01

    A survey of the thermophysical properties of terrestrial rock and debris-covered glaciers suggests these properties may be used to distinguish between massive debris-covered ice and intimate rock/ice mixtures in martian lobate debris aprons.

  10. Autogenic dynamics of debris-flow fans

    NASA Astrophysics Data System (ADS)

    van den Berg, Wilco; de Haas, Tjalling; Braat, Lisanne; Kleinhans, Maarten

    2015-04-01

    Alluvial fans develop their semi-conical shape by cyclic avulsion of their geomorphologically active sector from a fixed fan apex. These cyclic avulsions have been attributed to both allogenic and autogenic forcings and processes. Autogenic dynamics have been extensively studied on fluvial fans through physical scale experiments, and are governed by cyclic alternations of aggradation by unconfined sheet flow, fanhead incision leading to channelized flow, channel backfilling and avulsion. On debris-flow fans, however, autogenic dynamics have not yet been directly observed. We experimentally created debris-flow fans under constant extrinsic forcings, and show that autogenic dynamics are a fundamental intrinsic process on debris-flow fans. We found that autogenic cycles on debris-flow fans are driven by sequences of backfilling, avulsion and channelization, similar to the cycles on fluvial fans. However, the processes that govern these sequences are unique for debris-flow fans, and differ fundamentally from the processes that govern autogenic dynamics on fluvial fans. We experimentally observed that backfilling commenced after the debris flows reached their maximum possible extent. The next debris flows then progressively became shorter, driven by feedbacks on fan morphology and flow-dynamics. The progressively decreasing debris-flow length caused in-channel sedimentation, which led to increasing channel overflow and wider debris flows. This reduced the impulse of the liquefied flow body to the flow front, which then further reduced flow velocity and runout length, and induced further in-channel sedimentation. This commenced a positive feedback wherein debris flows became increasingly short and wide, until the channel was completely filled and the apex cross-profile was plano-convex. At this point, there was no preferential transport direction by channelization, and the debris flows progressively avulsed towards the steepest, preferential, flow path. Simultaneously

  11. A new debris sensor based on dual excitation sources for online debris monitoring

    NASA Astrophysics Data System (ADS)

    Hong, Wei; Wang, Shaoping; Tomovic, Mileta M.; Liu, Haokuo; Wang, Xingjian

    2015-09-01

    Mechanical systems could be severely damaged by loose debris generated through wear processes between contact surfaces. Hence, debris detection is necessary for effective fault diagnosis, life prediction, and prevention of catastrophic failures. This paper presents a new in-line debris sensor for hydraulic systems based on dual excitation sources. The proposed sensor makes magnetic lines more concentrated while at the same time improving magnetic field uniformity. As a result the sensor has higher sensitivity and improved precision. This paper develops the sensor model, discusses sensor structural features, and introduces a measurement method for debris size identification. Finally, experimental verification is presented indicating that that the sensor can effectively detect 81 μm (cube) or larger particles in 12 mm outside diameter (OD) organic glass pipe.

  12. Space Debris Mitigation CONOPS Development

    DTIC Science & Technology

    2013-06-01

    SPACE DEBRIS MITIGATION CONOPS DEVELOPMENT THESIS Earl B. Alejandro, Capt, USAF AFIT-ENV-13-J...04DL SPACE DEBRIS MITIGATION CONOPS DEVELOPMENT THESIS Presented to the Faculty Department of Systems Engineering and Management...June 2013 DISTRIBUTION STATEMENT A APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT-ENV-13-J-04DL SPACE DEBRIS

  13. Influence of the extent of disruption of Bakers' yeast on protein adsorption in expanded beds.

    PubMed

    Balasundaram, B; Harrison, S T L

    2008-02-01

    Expanded bed adsorption chromatography is used to capture the protein product of interest from a crude biological suspension directly, thereby eliminating the need for the removal of the cell debris. While this technique may replace three or four unit operations in a typical downstream process for biological product recovery, the adsorption process is influenced by the interaction between the microbial cells or cell debris and the adsorbent as well as the presence of contaminating solutes. The influence of the extent and nature of disruption of Bakers' yeast on the adsorption of the total soluble protein and alpha-glucosidase was investigated in this study. Two different techniques were used for cell disruption: high pressure homogenisation and hydrodynamic cavitation. Two different adsorbents were chosen: anionic Streamline DEAE and cationic Streamline SP. The settled bed height and the superficial velocity were constant across all experiments. The feedstock was characterised in terms of viscosity, pH, conductivity, particle size distribution of the cell debris and the extent of protein and alpha-glucosidase released. The performance of the adsorption process was found to be influenced by the electrostatic interactions of cell debris with the anionic adsorbent Streamline DEAE and the intraparticle diffusional resistance inside the pores of the adsorbent matrix. The increase in the intensity of disruption resulted in an increase in the dynamic binding capacity (10% feed) of both the total soluble protein and the alpha-glucosidase. However, the increase in the DBC of protein and alpha-glucosidase were not proportional. The amount of protein that could be adsorbed per ml of adsorbent from the samples subjected to a lower intensity of disruption was found to exceed that obtained at a higher disruption intensity on increasing the volume of feed suggesting multilayer adsorption. In this case, selective adsorption of the model protein alpha-glucosidase was reduced

  14. Detecting debris flows using ground vibrations

    USGS Publications Warehouse

    LaHusen, Richard G.

    1998-01-01

    Debris flows are rapidly flowing mixtures of rock debris, mud, and water that originate on steep slopes. During and following volcanic eruptions, debris flows are among the most destructive and persistent hazards. Debris flows threaten lives and property not only on volcanoes but far downstream in valleys that drain volcanoes where they arrive suddenly and inundate entire valley bottoms. Debris flows can destroy vegetation and structures in their path, including bridges and buildings. Their deposits can cover roads and railways, smother crops, and fill stream channels, thereby reducing their flood-carrying capacity and navigability.

  15. Remote Sensing of Plastic Debris

    NASA Astrophysics Data System (ADS)

    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.

  16. Operation of magnetically assisted fluidized beds in microgravity and variable gravity: experiment and theory

    NASA Technical Reports Server (NTRS)

    Sornchamni, T.; Jovanovic, G. N.; Reed, B. P.; Atwater, J. E.; Akse, J. R.; Wheeler, R. R.

    2004-01-01

    The conversion of solid waste into useful resources in support of long duration manned missions in space presents serious technological challenges. Several technologies, including supercritical water oxidation, microwave powered combustion and fluidized bed incineration, have been tested for the conversion of solid waste. However, none of these technologies are compatible with microgravity or hypogravity operating conditions. In this paper, we present the gradient magnetically assisted fluidized bed (G-MAFB) as a promising operating platform for fluidized bed operations in the space environment. Our experimental and theoretical work has resulted in both the development of a theoretical model based on fundamental principles for the design of the G-MAFB, and also the practical implementation of the G-MAFB in the filtration and destruction of solid biomass waste particles from liquid streams. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

  17. Separation Process of Fine Coals by Ultrasonic Vibration Gas-Solid Fluidized Bed

    PubMed Central

    Wei, Hua; Xie, Weining

    2017-01-01

    Ultrasonic vibration gas-solid fluidized bed was proposed and introduced to separate fine coals (0.5–0.125 mm fraction). Several technological methods such as XRF, XRD, XPS, and EPMA were used to study the composition of heavy products to evaluate the separation effect. Results show that the ultrasonic vibration force field strengthens the particle separation process based on density when the vibration frequency is 35 kHz and the fluidization number is 1.8. The ash difference between the light and heavy products and the recovery of combustible material obtain the maximum values of 47.30% and 89.59%, respectively. The sulfur content of the heavy product reaches the maximum value of 6.78%. Chemical state analysis of sulfur shows that organic sulfur (-C-S-), sulfate-sulfur (-SO4), and pyrite-sulfur (-S2) are confirmed in the original coal and heavy product. Organic sulfur (-C-S-) is mainly concentrated in the light product, and pyrite-sulfur (-S2) is significantly enriched in the heavy product. The element composition, phase composition, backscatter imagery, and surface distribution of elements for heavy product show concentration of high-density minerals including pyrite, quartz, and kaolinite. Some harmful elements such as F, Pb, and As are also concentrated in the heavy product. PMID:28845160

  18. Debris characterization diagnostic for the NIF

    NASA Astrophysics Data System (ADS)

    Miller, M. C.; Celeste, J. R.; Stoyer, M. A.; Suter, L. J.; Tobin, M. T.; Grun, J.; Davis, J. F.; Barnes, C. W.; Wilson, D. C.

    2001-01-01

    Generation of debris from targets and by x-ray ablation of surrounding materials will be a matter of concern for experimenters and National Ignition Facility (NIF) operations. Target chamber and final optics protection, for example debris shield damage, drive the interest for NIF operations. Experimenters are primarily concerned with diagnostic survivability, separation of mechanical versus radiation induced test object response in the case of effects tests, and radiation transport through the debris field when the net radiation output is used to benchmark computer codes. In addition, radiochemical analysis of activated capsule debris during ignition shots can provide a measure of the ablator <ρr>. Conceptual design of the Debris Monitor and Rad-Chem Station, one of the NIF core diagnostics, is presented. Methods of debris collection, particle size and mass analysis, impulse measurement, and radiochemical analysis are given. A description of recent experiments involving debris collection and impulse measurement on the OMEGA and Pharos lasers is also provided.

  19. Basal deposits and drusen in eyes with age-related maculopathy: evidence for solid lipid particles.

    PubMed

    Curcio, Christine A; Presley, J Brett; Millican, C Leigh; Medeiros, Nancy E

    2005-06-01

    Neutral lipid, including esterified cholesterol, and apolipoproteins B and E are abundant in basal deposits and drusen of aged and age-related maculopathy (ARM) eyes. The principal component of basal linear deposit (BlinD), a specific ARM lesion, is membranous debris, which if actually derived from membranes cannot account for extracellular neutral lipid. We therefore used a lipid-preserving ultrastructural method to obtain improved images of membranous debris. Maculas from 44 human donors (71-96 yr) were preserved <7.5 hr after death. Blocks were post-fixed in 2% osmium or osmium-tannic acid-paraphenylenediamine (OTAP) to preserve neutral lipid for thin-section transmission electron microscopic (TEM) examination. Solid particles identified by OTAP were considered closest to the in vivo state of extracellular lipids. Micrographs were examined for intermediate forms, with greatest weight given to comparable images from different preparations of same or fellow eyes. Twenty eyes of older adults (12 with ARM including fellows treated with photodynamic and radiation therapies) had adequately preserved extracellular lipid. The exterior surface of membranous debris was thicker and more electron-dense than basal infoldings of retinal pigment epithelium (RPE) cells. By OTAP, individual membranous debris profiles were solid (diameters, 80-200 nm) and formed tracks across or aggregations within basal laminar deposits. Solid particles and/or pools of neutral lipid were visible in BlinD and drusen. When processed to preserve lipid, membranous debris resembles neither membranes of surrounding cells nor vesicles possessing aqueous interiors but rather solid particles. These results are consistent with recent evidence implicating lipoprotein particles of intra-ocular origin as a potential source of neutral lipids, including esterified cholesterol, in the specific lesions of ARM.

  20. [Research progress in post-fire debris flow].

    PubMed

    Di, Xue-ying; Tao, Yu-zhu

    2013-08-01

    The occurrence of the secondary disasters of forest fire has significant impacts on the environment quality and human health and safety. Post-fire debris flow is one of the most hazardous secondary disasters of forest fire. To understand the occurrence conditions of post-fire debris flow and to master its occurrence situation are the critical elements in post-fire hazard assessment. From the viewpoints of vegetation, precipitation threshold and debris flow material sources, this paper elaborated the impacts of forest fire on the debris flow, analyzed the geologic and geomorphic conditions, precipitation and slope condition that caused the post-fire debris flow as well as the primary mechanisms of debris-flow initiation caused by shallow landslide or surface runoff, and reviewed the research progress in the prediction and forecast of post-fire debris flow and the related control measures. In the future research, four aspects to be focused on were proposed, i. e., the quantification of the relationships between the fire behaviors and environmental factors and the post-fire debris flow, the quantitative research on the post-fire debris flow initiation and movement processes, the mechanistic model of post-fire debris flow, and the rapid and efficient control countermeasures of post-fire debris flow.

  1. Deformation of debris-ice mixtures

    NASA Astrophysics Data System (ADS)

    Moore, Peter L.

    2014-09-01

    Mixtures of rock debris and ice are common in high-latitude and high-altitude environments and are thought to be widespread elsewhere in our solar system. In the form of permafrost soils, glaciers, and rock glaciers, these debris-ice mixtures are often not static but slide and creep, generating many of the landforms and landscapes associated with the cryosphere. In this review, a broad range of field observations, theory, and experimental work relevant to the mechanical interactions between ice and rock debris are evaluated, with emphasis on the temperature and stress regimes common in terrestrial surface and near-surface environments. The first-order variables governing the deformation of debris-ice mixtures in these environments are debris concentration, particle size, temperature, solute concentration (salinity), and stress. A key observation from prior studies, consistent with expectations, is that debris-ice mixtures are usually more resistant to deformation at low temperatures than their pure end-member components. However, at temperatures closer to melting, the growth of unfrozen water films at ice-particle interfaces begins to reduce the strengthening effect and can even lead to profound weakening. Using existing quantitative relationships from theoretical and experimental work in permafrost engineering, ice mechanics, and glaciology combined with theory adapted from metallurgy and materials science, a simple constitutive framework is assembled that is capable of capturing most of the observed dynamics. This framework highlights the competition between the role of debris in impeding ice creep and the mitigating effects of unfrozen water at debris-ice interfaces.

  2. Current orbital debris environment

    NASA Technical Reports Server (NTRS)

    Kessler, Donald J.

    1989-01-01

    NASA has instituted a plan for the definition of activities and resources required over the coming decade for the deepening of current understanding of anthropogenic orbital debris, and its effects on future mission operations. This understanding will be the basis of policy definition and policy implementation efforts. The most immediate requirement is the definition of the debris environment, with emphasis on data for debris sizes smaller than 4 cm. Systems-damage criteria and hypervelocity-impact theory will then be used to define the hazard to specific spacecraft.

  3. Space Debris: Its Causes and Management

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2002-01-01

    Orbital debris is internationally recognized as an environmental issue which needs to be addressed today to preserve near-Earth space for future generations. All major space agencies are committed to mitigating the growth of the debris environment. Many commercial space system operators have responded positively to orbital debris mitigation principles and recommendations. Orbital debris mitigation measures are most cost-effective if included in the design development phase.

  4. Micrometeoroids and debris

    NASA Technical Reports Server (NTRS)

    Potter, Andrew

    1989-01-01

    The materials with vulnerability to micrometeoroids and space debris are discussed. It is concluded that all materials are vulnerable to hypervelocity impacts and that the importance of these impacts depends on the function of material. It is also concluded that low earth orbits are the most significant region relative to orbital debris. The consequences of aerospace environment effects are discussed.

  5. Thiokol Solid Rocket Motors

    NASA Technical Reports Server (NTRS)

    Graves, S. R.

    2000-01-01

    This paper presents viewgraphs on thiokol solid rocket motors. The topics include: 1) Communications; 2) Military and government intelligence; 3) Positioning satellites; 4) Remote sensing; 5) Space burial; 6) Science; 7) Space manufacturing; 8) Advertising; 9) Space rescue space debris management; 10) Space tourism; 11) Space settlements; 12) Hazardous waste disposal; 13) Extraterrestrial resources; 14) Fast package delivery; and 15) Space utilities.

  6. Debris flow hazards mitigation--Mechanics, prediction, and assessment

    USGS Publications Warehouse

    Chen, C.-L.; Major, J.J.

    2007-01-01

    These proceedings contain papers presented at the Fourth International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction, and Assessment held in Chengdu, China, September 10-13, 2007. The papers cover a wide range of topics on debris-flow science and engineering, including the factors triggering debris flows, geomorphic effects, mechanics of debris flows (e.g., rheology, fluvial mechanisms, erosion and deposition processes), numerical modeling, various debris-flow experiments, landslide-induced debris flows, assessment of debris-flow hazards and risk, field observations and measurements, monitoring and alert systems, structural and non-structural countermeasures against debris-flow hazards and case studies. The papers reflect the latest devel-opments and advances in debris-flow research. Several studies discuss the development and appli-cation of Geographic Information System (GIS) and Remote Sensing (RS) technologies in debris-flow hazard/risk assessment. Timely topics presented in a few papers also include the development of new or innovative techniques for debris-flow monitoring and alert systems, especially an infra-sound acoustic sensor for detecting debris flows. Many case studies illustrate a wide variety of debris-flow hazards and related phenomena as well as their hazardous effects on human activities and settlements.

  7. Debris-flow generation from recently burned watersheds

    USGS Publications Warehouse

    Cannon, S.H.

    2001-01-01

    Evaluation of the erosional response of 95 recently burned drainage basins in Colorado, New Mexico and southern California to storm rainfall provides information on the conditions that result in fire-related debris flows. Debris flows were produced from only 37 of 95 (~40 percent) basins examined; the remaining basins produced either sediment-laden streamflow or no discernable response. Debris flows were thus not the prevalent response of the burned basins. The debris flows that did occur were most frequently the initial response to significant rainfall events. Although some hillslopes continued to erode and supply material to channels in response to subsequent rainfall events, debris flows were produced from only one burned basin following the initial erosive event. Within individual basins, debris flows initiated through both runoff and infiltration-triggered processes. The fact that not all burned basins produced debris flows suggests that specific geologic and geomorphic conditions may control the generation of fire-related debris flows. The factors that best distinguish between debris-flow producing drainages and those that produced sediment-laden streamflow are drainage-basin morphology and lithology, and the presence or absence of water-repellent soils. Basins underlain by sedimentary rocks were most likely to produce debris flows that contain large material, and sand- and gravel-dominated flows were generated primarily from terrain underlain by decomposed granite. Basin-area and relief thresholds define the morphologic conditions under which both types of debris flows occur. Debris flows containing large material are more likely to be produced from basins without water-repellent soils than from basins with water repellency. The occurrence of sand-and gravel-dominated debris flows depends on the presence of water-repellent soils.

  8. Comparison of an Inductance In-Line Oil Debris Sensor and Magnetic Plug Oil Debris Sensor

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Tuck, Roger; Showalter, Stephen

    2012-01-01

    The objective of this research was to compare the performance of an inductance in-line oil debris sensor and magnetic plug oil debris sensor when detecting transmission component health in the same system under the same operating conditions. Both sensors were installed in series in the NASA Glenn Spiral Bevel Gear Fatigue Rig during tests performed on 5 gear sets (pinion/gear) when different levels of damage occurred on the gear teeth. Results of this analysis found both the inductance in-line oil debris sensor and magnetic plug oil debris sensor have benefits and limitations when detecting gearbox component damage.

  9. Debris Detector Verification by Hvi-Tests

    NASA Astrophysics Data System (ADS)

    Bauer, Waldemar; Drolshagen, Gerhard; Vörsmann, Peter; Romberg, Oliver; Putzar, Robin

    Information regarding Space Debris (SD) or Micrometeoroids (MM) impacting on spacecraft (S/C) or payloads (P/L) can be obtained by using environmental models e.g. MASTER (ESA) or ORDEM (NASA). The validation of such models is performed by comparison of simulated results with measured or orbital observed data. The latter is utilised for large particles and can be obtained from ground based or space based radars or telescopes. Data regarding very small but abundant particles can also be gained by analysis of retrieved hardware (e.g. Hubble Space Telescope, Space Shuttle Windows), which are brought from orbit back to Earth. Furthermore, in-situ impact detectors are an essential source for information on small size meteoroids and space debris. These kind of detectors are placed in orbit and collect impact data regarding SD and MM, sending data near real time via telemetry. Compared to the impact data which is gained by analysis of retrieved surfaces, the detected data comprise additional information regarding exact impact time and, depending on the type of detector, on the orbit and particles composition. Nevertheless, existing detectors have limitations. Since the detection area is small, statistically meaningful number of impacts are obtained for very small particles only. Measurements of particles in the size range of hundreds of microns to mm which are potentially damaging to S/C require larger sensor areas. To make use of the advantages of in-situ impact detectors and to increase the amount of impact data an innovative impact detector concept is currently under development at DLR in Bremen. Different to all previous impact detectors the Solar Generator based Impact Detector (SOLID) is not an add-on component on the S/C. SOLID makes use of existing subsystems of the S/C and adopts them for impact detection purposes. Since the number of impacts on a target in space depends linearly on the exposed area, the S/C solar panels offer a unique opportunity to use them for

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

    PubMed

    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.

  11. A Phenomenological Approach to Wear Debris Analysis

    DTIC Science & Technology

    1996-04-01

    Ferrography ; oil analysis; wear debris analysis Introduction: Wear debris analysis is an important subject in maintenance, especially condition...diagnostic ol can be traced to Ferrography developed in the early 1970’s. Westcott and Seifert [1] state e heart and soul of Ferrography , or optical debris...monitoring, as follows. The key to Ferrography or optical examination of wear debris is to find marks or features on wear debris which suggest likely

  12. Debris Examination Using Ballistic and Radar Integrated Software

    NASA Technical Reports Server (NTRS)

    Griffith, Anthony; Schottel, Matthew; Lee, David; Scully, Robert; Hamilton, Joseph; Kent, Brian; Thomas, Christopher; Benson, Jonathan; Branch, Eric; Hardman, Paul; hide

    2012-01-01

    The Debris Examination Using Ballistic and Radar Integrated Software (DEBRIS) program was developed to provide rapid and accurate analysis of debris observed by the NASA Debris Radar (NDR). This software provides a greatly improved analysis capacity over earlier manual processes, allowing for up to four times as much data to be analyzed by one-quarter of the personnel required by earlier methods. There are two applications that comprise the DEBRIS system: the Automated Radar Debris Examination Tool (ARDENT) and the primary DEBRIS tool.

  13. Simulation of granular and gas-solid flows using discrete element method

    NASA Astrophysics Data System (ADS)

    Boyalakuntla, Dhanunjay S.

    2003-10-01

    In recent years there has been increased research activity in the experimental and numerical study of gas-solid flows. Flows of this type have numerous applications in the energy, pharmaceuticals, and chemicals process industries. Typical applications include pulverized coal combustion, flow and heat transfer in bubbling and circulating fluidized beds, hopper and chute flows, pneumatic transport of pharmaceutical powders and pellets, and many more. The present work addresses the study of gas-solid flows using computational fluid dynamics (CFD) techniques and discrete element simulation methods (DES) combined. Many previous studies of coupled gas-solid flows have been performed assuming the solid phase as a continuum with averaged properties and treating the gas-solid flow as constituting of interpenetrating continua. Instead, in the present work, the gas phase flow is simulated using continuum theory and the solid phase flow is simulated using DES. DES treats each solid particle individually, thus accounting for its dynamics due to particle-particle interactions, particle-wall interactions as well as fluid drag and buoyancy. The present work involves developing efficient DES methods for dense granular flow and coupling this simulation to continuum simulations of the gas phase flow. Simulations have been performed to observe pure granular behavior in vibrating beds. Benchmark cases have been simulated and the results obtained match the published literature. The dimensionless acceleration amplitude and the bed height are the parameters governing bed behavior. Various interesting behaviors such as heaping, round and cusp surface standing waves, as well as kinks, have been observed for different values of the acceleration amplitude for a given bed height. Furthermore, binary granular mixtures (granular mixtures with two particle sizes) in a vibrated bed have also been studied. Gas-solid flow simulations have been performed to study fluidized beds. Benchmark 2D

  14. Orbital Debris Modeling

    NASA Technical Reports Server (NTRS)

    Liou, J. C.

    2012-01-01

    Presentation outlne: (1) The NASA Orbital Debris (OD) Engineering Model -- A mathematical model capable of predicting OD impact risks for the ISS and other critical space assets (2) The NASA OD Evolutionary Model -- A physical model capable of predicting future debris environment based on user-specified scenarios (3) The NASA Standard Satellite Breakup Model -- A model describing the outcome of a satellite breakup (explosion or collision)

  15. Assessing the effects of check dams on sediment dynamics in a debris-flow catchment through SfM technique

    NASA Astrophysics Data System (ADS)

    Cucchiaro, Sara; Beinat, Alberto; Calsamiglia, Aleix; Cavalli, Marco; Cazorzi, Federico; Crema, Stefano; Marchi, Lorenzo

    2017-04-01

    The Moscardo Torrent (eastern Italian Alps) is a small rugged catchment (drainage area 4.1 km2, range in elevation between 890 and 2043 m) frequently affected by debris flows that deliver large amounts of sediment to the receiving stream, and cause concerns for infrastructures located on the alluvial fan and near the confluence. Over the last decades, hydraulic control works were implemented in the main channel to limit bed erosion and to stabilize channel banks. Although the objectives of training works have been only partly achieved, check dams and hillslope stabilization works have affected the sediment transfer from hillslopes to the channels and along the main channel. The effects of hydraulic control works were investigated by means of multi-temporal Structure from Motion (SfM) surveys based on images taken from the ground and UAV. The ground and air based surveys were carried out over a channel reach in which two check dams have recently been built. SfM surveys were taken before and after three debris-flow events (occurred between June and July 2016), allowing the generation of four high-resolution Digital Elevation Models (DEMs). Geomorphic changes caused by the debris-flow events have been assessed in order to produce the DEM of Differences (DoDs with a 0.2 m spatial resolution) that allowed estimating erosion and deposition volumes in the study area. Furthermore a debris-flow monitoring system has been in operation in the Moscardo Torrent; the analysis of the videos and of the hydrographs recorded by ultrasonic sensors permitted to assess the debris-flow volumes. These estimates were used to characterize the magnitude of events in support of the topographic analysis. By examining the changing pattern of erosion and deposition over time it was possible to understand the check dams' effects on sediment dynamics. The results show that the new check dams effectively stored sediment transported by the three debris flows. However, once the check dams have been

  16. Modeling biomass gasification in circulating fluidized beds

    NASA Astrophysics Data System (ADS)

    Miao, Qi

    In this thesis, the modeling of biomass gasification in circulating fluidized beds was studied. The hydrodynamics of a circulating fluidized bed operating on biomass particles were first investigated, both experimentally and numerically. Then a comprehensive mathematical model was presented to predict the overall performance of a 1.2 MWe biomass gasification and power generation plant. A sensitivity analysis was conducted to test its response to several gasifier operating conditions. The model was validated using the experimental results obtained from the plant and two other circulating fluidized bed biomass gasifiers (CFBBGs). Finally, an ASPEN PLUS simulation model of biomass gasification was presented based on minimization of the Gibbs free energy of the reaction system at chemical equilibrium. Hydrodynamics plays a crucial role in defining the performance of gas-solid circulating fluidized beds (CFBs). A 2-dimensional mathematical model was developed considering the hydrodynamic behavior of CFB gasifiers. In the modeling, the CFB riser was divided into two regions: a dense region at the bottom and a dilute region at the top of the riser. Kunii and Levenspiel (1991)'s model was adopted to express the vertical solids distribution with some other assumptions. Radial distributions of bed voidage were taken into account in the upper zone by using Zhang et al. (1991)'s correlation. For model validation purposes, a cold model CFB was employed, in which sawdust was transported with air as the fluidizing agent. A comprehensive mathematical model was developed to predict the overall performance of a 1.2 MWe biomass gasification and power generation demonstration plant in China. Hydrodynamics as well as chemical reaction kinetics were considered. The fluidized bed riser was divided into two distinct sections: (a) a dense region at the bottom of the bed where biomass undergoes mainly heterogeneous reactions and (b) a dilute region at the top where most of homogeneous

  17. Evaluating tsunami hazards from debris flows

    USGS Publications Warehouse

    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 debris flow enters the water. Three distinct regions (splash zone, near field, and far field) may be identified. Experiments demonstrate that characteristics of the near field water wave, which is the only coherent wave to emerge from the splash zone, depend primarily on debris flow volume, debris flow submerged time of motion, and water depth at the point where debris flow motion stops. Near field wave characteristics commonly may be used as & proxy source for computational tsunami propagation. This result is used to assess hazards associated with potential debris flows entering a reservoir in the northwestern USA. ?? 2003 Millpress,.

  18. Backwater development by woody debris

    NASA Astrophysics Data System (ADS)

    Geertsema, Tjitske; Torfs, Paul; Teuling, Ryan; Hoitink, Ton

    2017-04-01

    Placement of woody debris is a common method for increasing ecological values in river and stream restoration, and is thus widely used in natural environments. Water managers, however, are afraid to introduce wood in channels draining agricultural and urban areas. Upstream, it may create backwater, depending on hydrodynamic characteristics including the obstruction ratio, the Froude number and the surface level gradient. Patches of wood may trigger or counter morphological activity, both laterally, through bank erosion and protection, and vertically, with pool and riffle formation. Also, a permeable construction composed of wood will weather over time. Both morphodynamic activity and weathering cause backwater effects to change in time. The purpose of this study is to quantify the time development of backwater effects caused by woody debris. Hourly water levels gauged upstream and downstream of patches and discharge are collected for five streams in the Netherlands. The water level drop over the woody debris patch relates to discharge in the streams. This relation is characterized by an increasing water level difference for an increasing discharge, up to a maximum. If the discharge increases beyond this level, the water level difference reduces to the value that may represent the situation without woody debris. This reduction depends primarily on the obstruction ratio of the woody debris in the channel cross-section. Morphologic adjustments in the stream and reorientation of the woody material reduce the water level drop over the patches in time. Our results demonstrate that backwater effects can be reduced by optimizing the location where woody debris is placed and manipulating the obstruction ratio. Current efforts are focussed on representing woody debris in a one-dimensional numerical model, aiming to obtain a generic tool to achieve a stream design with woody debris that minimizes backwater.

  19. Orbital Debris and Future Environment Remediation

    NASA Technical Reports Server (NTRS)

    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

  20. Interaction between riverbed condition and characteristics of debris flow in Ichino-sawa subwatershed of Ohya-kuzure landslide, Japan

    NASA Astrophysics Data System (ADS)

    Tsunetaka, Haruka; Hotta, Norifumi; Imaizumi, Fumitoshi; Hayakawa, Yuichi S.; Yumen, Noriki

    2015-04-01

    Large-scale sediment movements, such as a deep-seated landslide, not only induce immediate sediment disasters but also produce a large amount of unstable sediment upstream. Most of the unstable sediment residing in the upstream area is discharged as debris flow. Hence, after the occurrence of large-scale sediment movement, debris flows have a long-term effect on the watershed regime. However, the characteristics of debris flow in upstream areas are not well understood, due to the topographic and grain-size conditions that are more complicated than the downstream area. This study was performed to reveal the relationship between such a riverbed condition and the characteristics of debris flow by field observations. The study site was Ichinosawa-subwatershed in the Ohya-kuzure basin, Shizuoka Prefecture, Japan. The basin experienced a deep-seated landslide about 300 years ago and is currently actively yielding sediment with a clear annual cycle. During the winter season, sediment is deposited on the valley bottom by freeze-thaw and weathering. In the summer season, the deposited sediment is discharged incrementally by debris flows related to storm events. Topographical survey and grain-size analysis were performed several times between November 2011 and November 2014. High-resolution digital elevation models (10 cm) were created from the results of a topographical survey using a terrestrial laser scanner. A grain-size analysis was conducted in the upper, middle, and lower parts of the study site. Debris flow occurrences were also monitored in the same period by a sensor-triggered video camera and interval camera. Rainfall was observed during the summer season for comparison with debris flow occurrence. Several debris flows of different magnitudes were observed during the study period. Although heavy rainfall events altered the bed inclination, the thickness of deposited sediment, and the grain-size distribution, more significant changes were detected after the debris

  1. NASA's New Orbital Debris Engineering Model, ORDEM2010

    NASA Technical Reports Server (NTRS)

    Krisko, Paula H.

    2010-01-01

    This paper describes the functionality and use of ORDEM2010, which replaces ORDEM2000, as the NASA Orbital Debris Program Office (ODPO) debris engineering model. Like its predecessor, ORDEM2010 serves the ODPO mission of providing spacecraft designers/operators and debris observers with a publicly available model to calculate orbital debris flux by current-state-of-knowledge methods. The key advance in ORDEM2010 is the input file structure of the yearly debris populations from 1995-2035 of sizes 10 micron - 1 m. These files include debris from low-Earth orbits (LEO) through geosynchronous orbits (GEO). Stable orbital elements (i.e., those that do not randomize on a sub-year timescale) are included in the files as are debris size, debris number, material density, random error and population error. Material density is implemented from ground-test data into the NASA breakup model and assigned to debris fragments accordingly. The random and population errors are due to machine error and uncertainties in debris sizes. These high-fidelity population files call for a much higher-level model analysis than what was possible with the populations of ORDEM2000. Population analysis in the ORDEM2010 model consists of mapping matrices that convert the debris population elements to debris fluxes. One output mode results in a spacecraft encompassing 3-D igloo of debris flux, compartmentalized by debris size, velocity, pitch, and yaw with respect to spacecraft ram direction. The second output mode provides debris flux through an Earth-based telescope/radar beam from LEO through GEO. This paper compares the new ORDEM2010 with ORDEM2000 in terms of processes and results with examples of specific orbits.

  2. Numerical simulation of a full-loop circulating fluidized bed under different operating conditions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, Yupeng; Musser, Jordan M.; Li, Tingwen

    Both experimental and computational studies of the fluidization of high-density polyethylene (HDPE) particles in a small-scale full-loop circulating fluidized bed are conducted. Experimental measurements of pressure drop are taken at different locations along the bed. The solids circulation rate is measured with an advanced Particle Image Velocimetry (PIV) technique. The bed height of the quasi-static region in the standpipe is also measured. Comparative numerical simulations are performed with a Computational Fluid Dynamics solver utilizing a Discrete Element Method (CFD-DEM). This paper reports a detailed and direct comparison between CFD-DEM results and experimental data for realistic gas-solid fluidization in a full-loopmore » circulating fluidized bed system. The comparison reveals good agreement with respect to system component pressure drop and inventory height in the standpipe. In addition, the effect of different drag laws applied within the CFD simulation is examined and compared with experimental results.« less

  3. Final Design for a Comprehensive Orbital Debris Management Program

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The rationale and specifics for the design of a comprehensive program for the control of orbital debris, as well as details of the various components of the overall plan, are described. The problem of orbital debris has been steadily worsening since the first successful launch in 1957. The hazards posed by orbital debris suggest the need for a progressive plan for the prevention of future debris, as well as the reduction of the current debris level. The proposed debris management plan includes debris removal systems and preventative techniques and policies. The debris removal is directed at improving the current debris environment. Because of the variance in sizes of debris, a single system cannot reasonably remove all kinds of debris. An active removal system, which deliberately retrieves targeted debris from known orbits, was determined to be effective in the disposal of debris tracked directly from earth. However, no effective system is currently available to remove the untrackable debris. The debris program is intended to protect the orbital environment from future abuses. This portion of the plan involves various environment from future abuses. This portion of the plan involves various methods and rules for future prevention of debris. The preventative techniques are protective methods that can be used in future design of payloads. The prevention policies are rules which should be employed to force the prevention of orbital debris.

  4. Improving hydrolysis of food waste in a leach bed reactor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Browne, James D.; Allen, Eoin; Murphy, Jerry D., E-mail: jerry.murphy@ucc.ie

    2013-11-15

    Highlights: • This paper assesses leaching of food waste in a two phase digestion system. • Leaching is assessed with and without an upflow anaerobic sludge blanket (UASB). • Without the UASB, low pH reduces hydrolysis, while increased flows increase leaching. • Inclusion of the UASB increases pH to optimal levels and greatly improves leaching. • The optimal conditions are suggested as low flow with connection to the UASB. - Abstract: This paper examines the rate of degradation of food waste in a leach bed reactor (LBR) under four different operating conditions. The effects of leachate recirculation at a lowmore » and high flow rate are examined with and without connection to an upflow anaerobic sludge blanket (UASB). Two dilution rates of the effective volume of the leach bed reactors were investigated: 1 and 6 dilutions per LBR per day. The increase in dilution rate from 1 to 6 improved the destruction of volatile solids without connection to the UASB. However connection to the UASB greatly improved the destruction of volatile solids (by almost 60%) at the low recirculation rate of 1 dilution per day. The increase in volatile solids destruction with connection to the UASB was attributed to an increase in leachate pH and buffering capacity provided by recirculated effluent from the UASB to the leach beds. The destruction of volatile solids for both the low and high dilution rates was similar with connection to the UASB, giving 82% and 88% volatile solids destruction respectively. This suggests that the most efficient leaching condition is 1 dilution per day with connection to the UASB.« less

  5. Orbital debris: Technical issues and future directions

    NASA Technical Reports Server (NTRS)

    Potter, Andrew (Editor)

    1992-01-01

    An international conference on orbital debris sponsored jointly by the American Institute of Aeronautics and Astronautics, NASA, and the Department of Defense, was held in Baltimore, Maryland, 16-19 Apr. 1990. Thirty-three papers were presented. The papers were grouped into the areas of measurements, modeling, and implications of orbital debris for space flight. New radar and optical measurements of orbital debris were presented that showed the existence of a large population of small debris. Modeling of potential future environments showed that runaway growth of the debris population from random collisions was a real possibility. New techniques for shielding against orbital debris and methods for removal of satellites from orbit were discussed.

  6. Plastic Beaches: occurrence and accumulation of marine debris on barrier islands in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Wessel, C.; Albins, K.; Cebrian, J.

    2016-02-01

    Marine debris is any persistent solid material that is manufactured or processed and directly or indirectly, intentionally or unintentionally, disposed of or abandoned into the marine environment (33USC§1951). Marine debris is an economic, environmental, human health and aesthetic problem posing a complex challenge. Coastal communities are among the most seriously affected because of increased expenses for beach cleaning, public health and waste disposal, as well as a loss of income from decreased tourism. To better document this problem we are monitoring the occurrence and accumulation rate of marine debris on 6 barrier islands in the northern Gulf of Mexico (nGoM). Surveys are conducted at low tide and consist of 100m-long transects along the shoreline extending from the water edge to the upland shoreline limit. All debris larger than 5 mm is collected and recorded. Debris is then sorted by material, and dry mass is recorded. With this information we are investigating four specific questions: (1) what are the major types and possible sources (land or ocean based) of shoreline debris; (2) does the rate of debris deposition onto the shoreline show seasonal oscillations; (3) how does debris deposition change from east to west in the nGoM; and (4) what are the possible causes of the temporal and spatial trends found (e.g. rainfall and runoff, human population, boat traffic)? During the first year of sampling we are beginning to see trends emerge. More trash consistently washes up on the ocean side versus the sound side of the barrier islands, which suggests either large amounts of trash in the nGoM is ocean-based debris, or it is driven by beach goers, or both. In addition, we have found a significant increase in the amount of trash on the shoreline during tourist/boating season (May to September), although trash items tend to be smaller in size during that season. At the presentation we will discuss these and other trends that emerge with a more complete data set.

  7. Anthropogenic Debris Ingestion by Avifauna in Eastern Australia

    PubMed Central

    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. PMID:27574986

  8. Strategy for mitigation of marine debris: analysis of sources and composition of marine debris in northern Taiwan.

    PubMed

    Kuo, Fan-Jun; Huang, Hsiang-Wen

    2014-06-15

    Six sites (two sites for each of rocky shores, sandy beaches, and fishing ports) in northern Taiwan were selected to investigate the amount and density of marine debris in each of the four seasons and after spring and neap tides from 2012 to 2013. The results indicate that marine debris was higher on rocky shores than sandy beaches and fishing ports. There is no significant difference between season and tide. The dominant debris was plastic-type, followed by polystyrene. The majority of debris originated from recreational activities, followed from ocean/waterway activities. The results suggest that the following actions are needed: (1) continue and reinforce the plastic-limit policy; (2) increase the cleaning frequency at rocky shores; (3) promote marine environmental education, with a goal of debris-free coasts; (4) recycle fishing gear and to turn that gear into energy; and (5) coordinate between agencies to establish a mechanism to monitor debris. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Controlling the Growth of Future LEO Debris Populations with Active Debris Removal

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.; Johnson, N. L.; Hill, N. M.

    2008-01-01

    Active debris removal (ADR) was suggested as a potential means to remediate the low Earth orbit (LEO) debris environment as early as the 1980s. The reasons ADR has not become practical are due to its technical difficulties and the high cost associated with the approach. However, as the LEO debris populations continue to increase, ADR may be the only option to preserve the near-Earth environment for future generations. An initial study was completed in 2007 to demonstrate that a simple ADR target selection criterion could be developed to reduce the future debris population growth. The present paper summarizes a comprehensive study based on more realistic simulation scenarios, including fragments generated from the 2007 Fengyun-1C event, mitigation measures, and other target selection options. The simulations were based on the NASA long-term orbital debris projection model, LEGEND. A scenario, where at the end of mission lifetimes, spacecraft and upper stages were moved to 25-year decay orbits, was adopted as the baseline environment for comparison. Different annual removal rates and different ADR target selection criteria were tested, and the resulting 200-year future environment projections were compared with the baseline scenario. Results of this parametric study indicate that (1) an effective removal strategy can be developed based on the mass and collision probability of each object as the selection criterion, and (2) the LEO environment can be stabilized in the next 200 years with an ADR removal rate of five objects per year.

  10. Does bone debris in anterior cruciate ligament reconstruction really matter? A cohort study of a protocol for bone debris debridement

    PubMed Central

    Imam, Mohamed A.; Abdelkafy, Ashraf; Dinah, Feroz; Adhikari, Ajeya

    2015-01-01

    Background: The purpose of the current study was to determine whether a systematic five-step protocol for debridement and evacuation of bone debris during anterior cruciate ligament reconstruction (ACLR) reduces the presence of such debris on post-operative radiographs. Methods: A five-step protocol for removal of bone debris during arthroscopic assisted ACLR was designed. It was applied to 60 patients undergoing ACLR (Group 1), and high-quality digital radiographs were taken post-operatively in each case to assess for the presence of intra-articular bone debris. A control group of 60 consecutive patients in whom no specific bone debris protocol was applied (Group 2) and their post-operative radiographs were also checked for the presence of intra-articular bone debris. Results: In Group 1, only 15% of post-operative radiographs showed residual bone debris, compared to 69% in Group 2 (p < 0.001). Conclusion: A five-step systematic protocol for bone debris removal during arthroscopic assisted ACLR resulted in a significant decrease in residual bone debris seen on high-quality post-operative radiographs. PMID:27163060

  11. Derivation of debris flow critical rainfall thresholds from land stability modeling

    NASA Astrophysics Data System (ADS)

    Papa, M. N.; Medina, V.; Bateman, A.; Ciervo, F.

    2012-04-01

    The aim of the work is to develop a system capable of providing debris flow warnings in areas where historical events data are not available as well as in the case of changing environments and climate. For these reasons, critical rainfall threshold curves are derived from mathematical and numerical simulations rather than the classical derivation from empirical rainfall data. The operational use of distributed model, based on the stability analysis for each grid cell of the basin, is not feasible in the case of warnings due to the long running time required for this kind of model as well as the lack of detailed information on the spatial distribution of the properties of the material in many practical cases. Moreover, with the aim of giving debris flow warnings, it is not necessary to know the distribution of instable elements along the basin but only if a debris flow may affect the vulnerable areas in the valley. The capability of a debris flow of reaching the downstream areas depends on many factors linked with the topography, the solid concentration, the rheological properties of the debris mixture and the flow discharge as well as the occurrence of liquefaction of the sliding mass. In relation to a specific basin, many of these factors may be considered as not time dependent. The most rainfall dependent factors are flow discharge and correlated total debris volume. In the present study, the total volume that is instable, and therefore available for the flow, is considered as the governing factor from which it is possible to assess whether a debris flow will affect the downstream areas or not. The possible triggering debris flow is simulated, in a generic element of the basin, by an infinite slope stability analysis. The groundwater pressure is calculated by the superposition of the effect of an "antecedent" rainfall and an "event" rainfall. The groundwater pressure response to antecedent rainfall is used as the initial condition for the time

  12. Debris dams and the relief of headwater streams.

    Treesearch

    S.T. Lancaster; G.E. Grant

    2005-01-01

    In forested, mountain landscapes where debris flows are common, valley-spanning debris dams formed by debris-flow deposition are a common feature of headwater valleys. In this paper, we examine how wood and boulder steps, i.e., debris dams, affect longitudinal profile relief and gradient at the debris-flow-fluvial transition in three sites in the Oregon Coast Range,...

  13. Synergy of debris mitigation and removal

    NASA Astrophysics Data System (ADS)

    Lewis, Hugh G.; White, Adam E.; Crowther, Richard; Stokes, Hedley

    2012-12-01

    Since the end of the 20th Century there has been considerable effort made to devise mitigation measures to limit the growth of the debris population. This activity has led to the implementation of a "25-year rule" by a number of space-faring nations for the post-mission disposal of spacecraft and orbital stages intersecting the Low Earth Orbit (LEO) region. Through the use of projections made by computer models, it was anticipated that this 25-year rule, together with passivation and suppression of mission-related debris, would be sufficient to prevent the unconstrained growth of the LEO debris population. In the last decade both the LEO debris environment and the debris modelling capability have seen significant changes. In particular, recent population growth has been driven by a number of major break-ups, including the intentional destruction of the Fengyun-1C spacecraft and the collision between Iridium 33 and Cosmos 2251. State-of-the-art evolutionary models indicate that the LEO debris population will continue to grow in spite of good compliance with the commonly adopted mitigation measures and even in the absence of new launches. Consequently, this has led to considerable interest in the development of remediation measures and, especially, in debris removal. In this paper, we present a new and large study of debris mitigation and removal using the University of Southampton's evolutionary model, DAMAGE, together with the latest MASTER model population of objects ≥10 cm in LEO. Here, we have employed a concurrent approach to mitigation and remediation, whereby changes to the PMD rule and the inclusion of other mitigation measures have been considered together with multiple removal strategies. In this way, we have been able to demonstrate the synergy of these mitigation and remediation measures and to identify potential, aggregate solutions to the space debris problem. The results suggest that reducing the PMD rule offers benefits that include an increase in

  14. Impact of the 2008 Wenchuan earthquake in China on subsequent long-term debris flow activities in the epicentral area

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Zhang, L. M.

    2017-01-01

    The 2008 Wenchuan earthquake triggered the largest number of landslides among the recent strong earthquake events around the world. The loose landslide materials were retained on steep terrains and deep gullies. In the period from 2008 to 2015, numerous debris flows occurred during rainstorms along the Provincial Road 303 (PR303) near the epicentre of the earthquake, causing serious damage to the reconstructed highway. Approximately 5.24 × 106 m3 of debris-flow sediment was deposited shortly after the earthquake. This paper evaluates the evolution of the debris flows that occurred after the Wenchuan earthquake, which helps understand long-term landscape evolution and cascading effects in regions impacted by mega earthquakes. With the aid of a GIS platform combined with field investigations, we continuously tracked movements of the loose deposit materials in all the debris flow gullies along an 18 km reach of PR303 and the characteristics of the regional debris flows during several storms in the past seven years. This paper presents five important aspects of the evolution of debris flows: (1) supply of debris flow materials; (2) triggering rainfall; (3) initiation mechanisms and types of debris flows; (4) runout characteristics; and (5) elevated riverbed due to the deposited materials from the debris flows. The hillslope soil deposits gradually evolved into channel deposits and the solid materials in the channels moved towards the ravine mouth. Accordingly, channelized debris flows became dominant gradually. Due to the decreasing source material volume and changes in debris flow characteristics, the triggering rainfall tends to increase from 30 mm h- 1 in 2008 to 64 mm h- 1 in 2013, and the runout distance tends to decrease over time. The runout materials blocked the river and elevated the riverbed by at least 30 m in parts of the study area. The changes in the post-seismic debris flow activity can be categorized into three stages, i.e., active, unstable, and

  15. Small satellites and space debris issues

    NASA Astrophysics Data System (ADS)

    Yakovlev, M.; Kulik, S.; Agapov, V.

    2001-10-01

    The objective of this report is the analysis of the tendencies in designing of small satellites (SS) and the effect of small satellites on space debris population. It is shown that SS to include nano- and pico-satellites should be considered as a particularly dangerous source of space debris when elaborating international standards and legal documents concerning the space debris problem, in particular "International Space Debris Mitigation Standard". These issues are in accordance with the IADC goals in its main activity areas and should be carefully considered within the IADC framework.

  16. Incidence of Debris Discs Around FGK Stars in the Solar Neighbourhood

    NASA Technical Reports Server (NTRS)

    Montesinos, B.; Eiroa, C.; Krivov, A. V.; Marshall, J. P.; Pilbratt, G. L.; Liseau, R.; Mora, A.; Maldonado, J.; Wolf, S.; Ertel, S.; hide

    2016-01-01

    Context. Debris discs are a consequence of the planet formation process and constitute the fingerprints of planetesimal systems. Their counterparts in the solar system are the asteroid and Edgeworth-Kuiper belts. Aims. The aim of this paper is to provide robust numbers for the incidence of debris discs around FGK stars in the solar neighborhood. Methods. The full sample of 177 FGK stars with d approx. less than 20 pc proposed for the DUst around NEarby Stars (DUNES) survey is presented. Herschel/PACS observations at 100 and 160 micrometers were obtained, and were complemented in some cases with data at 70 micrometers and at 250, 350, and 500 micrometer SPIRE photometry. The 123 objects observed by the DUNES collaboration were presented in a previous paper. The remaining 54 stars, shared with the Disc Emission via a Bias-free Reconnaissance in IR and Sub-mm (DEBRIS) consortium and observed by them, and the combined full sample are studied in this paper. The incidence of debris discs per spectral type is analyzed and put into context together with other parameters of the sample, like metallicity, rotation and activity, and age. Results. The subsample of 105 stars with d approx. less than 15 pc containing 23 F, 33 G, and 49 K stars is complete for F stars, almost complete for G stars, and contains a substantial number of K stars from which we draw solid conclusions on objects of this spectral type. The incidence rates of debris discs per spectral type are 0.26(+0.21/-0.14) (6 objects with excesses out of 23 F stars), 0.21(+0.17/-0.11) (7 out of 33 G stars), and 0.20(+0.14/-0.09) (10 out of 49 K stars); the fraction for all three spectral types together is 0.22(+0.08/-0.07) (23 out of 105 stars).The uncertainties correspond to a 95 confidence level. The medians of the upper limits of L(sub dust)/L(sub *) for each spectral type are 7.8 x 10(exp -7) (F), 1.4 x 10(exp -6) (G), and 2.2 x 10(exp -6) (K); the lowest values are around 4.0 x 10(exp -7). The incidence of debris

  17. Orbital Debris Quarterly News, Vol. 13, No. 2

    NASA Technical Reports Server (NTRS)

    Liou, J.-C. (Editor); Shoots, Debi (Editor)

    2009-01-01

    Topics include: debris clouds left by satellite collision; debris flyby near the International Space Station; and break-up of an ullage motor from a Russian Proton launch vehicle. Findings from the analysis of the STS-126 Shuttle Endeavour window impact damage are provided. Abstracts from the NASA Orbital Debris program office are presented and address a variety of topics including: Reflectance Spectra Comparison of Orbital Debris, Intact Spacecraft, and Intact Rocket Bodies in the GEO Regime; Shape Distribution of Fragments From Microsatellite Impact Tests; Micrometeoroid and Orbital Debris Threat Mitigation Techniques for the Space Shuttle Orbiter; Space Debris Environment Remediation Concepts; and, In Situ Measurement Activities at the NASA Orbital Debris Program Office. Additionally, a Meeting Report is provided for the 12 meeting of the NASA/DoD Orbital Debris Working Group.

  18. 14 CFR 420.65 - Handling of solid propellants.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Handling of solid propellants. 420.65 Section 420.65 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION... from the closest debris or explosive hazard source in an explosive hazard facility. ...

  19. 14 CFR 420.65 - Handling of solid propellants.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Handling of solid propellants. 420.65 Section 420.65 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION... from the closest debris or explosive hazard source in an explosive hazard facility. ...

  20. 14 CFR 420.65 - Handling of solid propellants.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Handling of solid propellants. 420.65 Section 420.65 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION... from the closest debris or explosive hazard source in an explosive hazard facility. ...

  1. Orbital debris removal and meteoroid deflection

    NASA Astrophysics Data System (ADS)

    Campbell, Jonathan W.; Taylor, Charles R.; Smalley, Larry L.; Dickerson, Thomas

    1998-11-01

    Orbital debris in low-Earth orbit in the size range from 1 to 10 cm in diameter can be detected but not tracked reliably enough to be avoided by spacecraft. It can cause catastrophic damage even to a shielded spacecraft. With adaptive optics, a ground-based pulsed laser ablating the debris surface can produce enough propulsion in several hundred pulses to cause such debris to reenter the atmosphere. A single laser station could remove all of the 1 - 10 cm debris in three years or less. A technology demonstration of laser space propulsion is proposed which would pave the way for the implementation of such a debris removal system. The cost of the proposed demonstration is comparable with the estimated annual cost of spacecraft operations in the present orbital debris environment. Orbital debris is not the only space junk that is deleterious to the Earth's environment. Collisions with asteroids have caused major havoc to the Earth's biosphere many times in the ancient past. Since the possibility still exists for major impacts of asteroids with the Earth, it shown that it is possible to scale up the systems to prevent these catastrophic collisions providing sufficient early warning is available from new generation space telescopes plus deep space radar tracking.

  2. Space debris mitigation - engineering strategies

    NASA Astrophysics Data System (ADS)

    Taylor, E.; Hammond, M.

    The problem of space debris pollution is acknowledged to be of growing concern by space agencies, leading to recent activities in the field of space debris mitigation. A review of the current (and near-future) mitigation guidelines, handbooks, standards and licensing procedures has identified a number of areas where further work is required. In order for space debris mitigation to be implemented in spacecraft manufacture and operation, the authors suggest that debris-related criteria need to become design parameters (following the same process as applied to reliability and radiation). To meet these parameters, spacecraft manufacturers and operators will need processes (supported by design tools and databases and implementation standards). A particular aspect of debris mitigation, as compared with conventional requirements (e.g. radiation and reliability) is the current and near-future national and international regulatory framework and associated liability aspects. A framework for these implementation standards is presented, in addition to results of in-house research and development on design tools and databases (including collision avoidance in GTO and SSTO and evaluation of failure criteria on composite and aluminium structures).

  3. Debris-flow mobilization from landslides

    USGS Publications Warehouse

    Iverson, R.M.; Reid, M.E.; LaHusen, R.G.

    1997-01-01

    Field observations, laboratory experiments, and theoretical analyses indicate that landslides mobilize to form debris flows by three processes: (a) widespread Coulomb failure within a sloping soil, rock, or sediment mass, (b) partial or complete liquefaction of the mass by high pore-fluid pressures, and (c) conversion of landslide translational energy to internal vibrational energy (i.e. granular temperature). These processes can operate independently, but in many circumstances they appear to operate simultaneously and synergistically. Early work on debris-flow mobilization described a similar interplay of processes but relied on mechanical models in which debris behavior was assumed to be fixed and governed by a Bingham or Bagnold rheology. In contrast, this review emphasizes models in which debris behavior evolves in response to changing pore pressures and granular temperatures. One-dimensional infinite-slope models provide insight by quantifying how pore pressures and granular temperatures can influence the transition from Coulomb failure to liquefaction. Analyses of multidimensional experiments reveal complications ignored in one-dimensional models and demonstrate that debris-flow mobilization may occur by at least two distinct modes in the field.

  4. Volcanic debris flows in developing countries - The extreme need for public education and awareness of debris-flow hazards

    USGS Publications Warehouse

    Major, J.J.; Schilling, S.P.; Pullinger, C.R.; ,

    2003-01-01

    In many developing countries, volcanic debris flows pose a significant societal risk owing to the distribution of dense populations that commonly live on or near a volcano. At many volcanoes, modest volume (up to 500,000 m 3) debris flows are relatively common (multiple times per century) and typically flow at least 5 km along established drainages. Owing to typical debris-flow velocities there is little time for authorities to provide effective warning of the occurrence of a debris flow to populations within 10 km of a source area. Therefore, people living, working, or recreating along channels that drain volcanoes must learn to recognize potentially hazardous conditions, be aware of the extent of debris-flow hazard zones, and be prepared to evacuate to safer ground when hazardous conditions develop rather than await official warnings or intervention. Debris-flow-modeling and hazard-assessment studies must be augmented with public education programs that emphasize recognizing conditions favorable for triggering landslides and debris flows if effective hazard mitigation is to succeed. ?? 2003 Millpress,.

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

    NASA Astrophysics Data System (ADS)

    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

  6. Intelligent Launch and Range Operations Virtual Test Bed (ILRO-VTB)

    NASA Technical Reports Server (NTRS)

    Bardina, Jorge; Rajkumar, T.

    2003-01-01

    Intelligent Launch and Range Operations Virtual Test Bed (ILRO-VTB) is a real-time web-based command and control, communication, and intelligent simulation environment of ground-vehicle, launch and range operation activities. ILRO-VTB consists of a variety of simulation models combined with commercial and indigenous software developments (NASA Ames). It creates a hybrid software/hardware environment suitable for testing various integrated control system components of launch and range. The dynamic interactions of the integrated simulated control systems are not well understood. Insight into such systems can only be achieved through simulation/emulation. For that reason, NASA has established a VTB where we can learn the actual control and dynamics of designs for future space programs, including testing and performance evaluation. The current implementation of the VTB simulates the operations of a sub-orbital vehicle of mission, control, ground-vehicle engineering, launch and range operations. The present development of the test bed simulates the operations of Space Shuttle Vehicle (SSV) at NASA Kennedy Space Center. The test bed supports a wide variety of shuttle missions with ancillary modeling capabilities like weather forecasting, lightning tracker, toxic gas dispersion model, debris dispersion model, telemetry, trajectory modeling, ground operations, payload models and etc. To achieve the simulations, all models are linked using Common Object Request Broker Architecture (CORBA). The test bed provides opportunities for government, universities, researchers and industries to do a real time of shuttle launch in cyber space.

  7. POST Earthquake Debris Management - AN Overview

    NASA Astrophysics Data System (ADS)

    Sarkar, Raju

    Every year natural disasters, such as fires, floods, earthquakes, hurricanes, landslides, tsunami, and tornadoes, challenge various communities of the world. Earthquakes strike with varying degrees of severity and pose both short- and long-term challenges to public service providers. Earthquakes generate shock waves and displace the ground along fault lines. These seismic forces can bring down buildings and bridges in a localized area and damage buildings and other structures in a far wider area. Secondary damage from fires, explosions, and localized flooding from broken water pipes can increase the amount of debris. Earthquake debris includes building materials, personal property, and sediment from landslides. The management of this debris, as well as the waste generated during the reconstruction works, can place significant challenges on the national and local capacities. Debris removal is a major component of every post earthquake recovery operation. Much of the debris generated from earthquake is not hazardous. Soil, building material, and green waste, such as trees and shrubs, make up most of the volume of earthquake debris. These wastes not only create significant health problems and a very unpleasant living environment if not disposed of safely and appropriately, but also can subsequently impose economical burdens on the reconstruction phase. In practice, most of the debris may be either disposed of at landfill sites, reused as materials for construction or recycled into useful commodities Therefore, the debris clearance operation should focus on the geotechnical engineering approach as an important post earthquake issue to control the quality of the incoming flow of potential soil materials. In this paper, the importance of an emergency management perspective in this geotechnical approach that takes into account the different criteria related to the operation execution is proposed by highlighting the key issues concerning the handling of the construction

  8. Ability of organic and inorganic bedding materials to promote growth of environmental bacteria.

    PubMed

    Godden, S; Bey, R; Lorch, K; Farnsworth, R; Rapnicki, P

    2008-01-01

    The major objective of this study was to contrast the ability of 4 commonly utilized bedding materials to promote growth of environmental bacteria under controlled conditions. A second objective was to describe the relationship between bacterial growth and specific biochemical or nutritional properties of these bedding materials. Unused samples of clean sand (CS; n = 20), recycled sand (RS; n = 21), digested manure solids (DS; n = 15), and shavings (SH; n = 15) were collected from bedding storage areas on 49 commercial Minnesota and Wisconsin dairy farms. Sterilized bedding samples were inoculated with Klebsiella pneumoniae and Enterococcus faecium then incubated, in triplicate, for 72 h at 37 degrees C. Subsamples were collected after 0, 24, 48, and 72 h of incubation for culture and enumeration of bacteria. Subsamples of bedding were also tested for pH, total C content (%), and total N content (%). If bacterial growth occurred, peak levels were typically achieved within 24 h. Digested manure solids promoted the greatest amounts of growth of K. pneumoniae, followed by RS and then SH, whereas CS promoted the least. There would seem to be a tradeoff in selecting SH as a bedding material, because it supported moderate growth of K. pneumoniae but caused a rapid decline in the numbers of E. faecium. However, RS, CS, and DS each only supported relatively small amounts of growth of E. faecium, so the benefit of SH relative to other bedding materials is limited. High bedding pH may partially explain why some bedding materials supported growth of E. faecium (e.g., DS and RS). Both high bedding pH (e.g., as for DS or RS) and high total C (%) content (e.g., as for DS and SH) may partially explain why some bedding materials supported growth of K. pneumoniae.

  9. Optical Observations of Space Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Abercromby, Kira; Rodriquez, Heather; Barker, Edwin S.; Kelecy, Thomas

    2008-01-01

    This viewgraph presentation reviews the use of optical telescopes to observe space debris. .It will present a brief review of how the survey is conducted, and what some of the significant results encompass. The goal is to characterize the population of debris objects at GEO, with emphasis on the faint object population. Because the survey observations extend over a very short arc (5 minutes), a full six parameter orbit can not be determined. Recently we have begun to use a second telescope, the 0.9-m at CTIO, as a chase telescope to do follow-up observations of potential GEO debris candidates found by MODEST. With a long enough sequence of observations, a full six-parameter orbit including eccentricity can be determined. The project has used STK since inception for planning observing sessions based on the distribution of bright cataloged objects and the anti-solar point (to avoid eclipse). Recently, AGI's Orbit Determination Tool Kit (ODTK) has been used to determine orbits, including the effects of solar radiation pressure. Since an unknown fraction of the faint debris at GEO has a high area-to-mass ratio (A/M), the orbits are perturbed significantly by solar radiation. The ODTK analysis results indicate that temporal variations in the solar perturbations, possibly due to debris orientation dynamics, can be estimated in the OD process. Additionally, the best results appear to be achieved when solar forces orthogonal to the object-Sun line are considered. Determining the A/M of individual objects and the distribution of A/M values of a large sample of debris is important to understanding the total population of debris at GEO

  10. Modeling and Observations of Debris Disks

    NASA Astrophysics Data System (ADS)

    Moro-Martín, Amaya

    2009-08-01

    Debris disks are disks of dust observed around mature main sequence stars (generally A to K2 type). They are evidence that these stars harbor a reservoir of dust-producing plantesimals on spatial scales that are similar to those found for the small-body population of our solar system. Debris disks present a wide range of sizes and structural features (inner cavities, warps, offsets, rings, clumps) and there is growing evidence that, in some cases, they might be the result of the dynamical perturbations of a massive planet. Our solar system also harbors a debris disk and some of its properties resemble those of extra-solar debris disks. The study of these disks can shed light on the diversity of planetary systems and can help us place our solar system into context. This contribution is an introduction to the debris disk phenomenon, including a summary of debris disks main properties (§1-based mostly on results from extensive surveys carried out with Spitzer), and a discussion of what they can teach us about the diversity of planetary systems (§2).

  11. External tank space debris considerations

    NASA Technical Reports Server (NTRS)

    Elfer, N.; Baillif, F.; Robinson, J.

    1992-01-01

    Orbital debris issues associated with maintaining a Space Shuttle External Tank (ET) on orbit are presented. The first issue is to ensure that the ET does not become a danger to other spacecraft by generating space debris, and the second is to protect the pressurized ET from penetration by space debris or meteoroids. Tests on shield designs for penetration resistance showed that when utilized with an adequate bumper, thermal protection system foam on the ET is effective in preventing penetration.

  12. A depth-averaged debris-flow model that includes the effects of evolving dilatancy: II. Numerical predictions and experimental tests.

    USGS Publications Warehouse

    George, David L.; Iverson, Richard M.

    2014-01-01

    We evaluate a new depth-averaged mathematical model that is designed to simulate all stages of debris-flow motion, from initiation to deposition. A companion paper shows how the model’s five governing equations describe simultaneous evolution of flow thickness, solid volume fraction, basal pore-fluid pressure, and two components of flow momentum. Each equation contains a source term that represents the influence of state-dependent granular dilatancy. Here we recapitulate the equations and analyze their eigenstructure to show that they form a hyperbolic system with desirable stability properties. To solve the equations we use a shock-capturing numerical scheme with adaptive mesh refinement, implemented in an open-source software package we call D-Claw. As tests of D-Claw, we compare model output with results from two sets of large-scale debris-flow experiments. One set focuses on flow initiation from landslides triggered by rising pore-water pressures, and the other focuses on downstream flow dynamics, runout, and deposition. D-Claw performs well in predicting evolution of flow speeds, thicknesses, and basal pore-fluid pressures measured in each type of experiment. Computational results illustrate the critical role of dilatancy in linking coevolution of the solid volume fraction and pore-fluid pressure, which mediates basal Coulomb friction and thereby regulates debris-flow dynamics.

  13. Sampling supraglacial debris thickness using terrestrial photogrammetry

    NASA Astrophysics Data System (ADS)

    Nicholson, Lindsey; Mertes, Jordan

    2017-04-01

    The melt rate of debris-covered ice differs to that of clean ice primarily as a function of debris thickness. The spatial distribution of supraglacial debris thickness must therefore be known in order to understand how it is likely to impact glacier behaviour, and meltwater contribution to local hydrological resources and global sea level rise. However, practical means of determining debris cover thickness remain elusive. In this study we explore the utility of terrestrial photogrammetry to produce high resolution, scaled and texturized digital terrain models of debris cover exposures above ice cliffs as a means of quantifying and characterizing debris thickness. Two Nikon D5000 DSLRs with Tamron 100mm lenses were used to photograph a sample area of the Ngozumpa glacier in the Khumbu Himal of Nepal in April 2016. A Structure from Motion workflow using Agisoft Photoscan software was used to generate a surface models with <10cm resolution. A Trimble Geo7X differential GPS with Zephyr antenna, along with a local base station, was used to precisely measure marked ground control points to scale the photogrammetric surface model. Measurements of debris thickness along the exposed cliffline were made from this scaled model, assuming that the ice surface at the debris-ice boundary is horizontal, and these data are compared to 50 manual point measurements along the same clifftops. We conclude that sufficiently high resolution photogrammetry, with precise scaling information, provides a useful means to determine debris thickness at clifftop exposures. The resolution of the possible measurements depends on image resolution, the accuracy of the ground control points and the computational capacity to generate centimetre scale surface models. Application of such techniques to sufficiently high resolution imagery from UAV-borne cameras may offer a powerful means of determining debris thickness distribution patterns over debris covered glacier termini.

  14. Waste tyre pyrolysis: modelling of a moving bed reactor.

    PubMed

    Aylón, E; Fernández-Colino, A; Murillo, R; Grasa, G; Navarro, M V; García, T; Mastral, A M

    2010-12-01

    This paper describes the development of a new model for waste tyre pyrolysis in a moving bed reactor. This model comprises three different sub-models: a kinetic sub-model that predicts solid conversion in terms of reaction time and temperature, a heat transfer sub-model that calculates the temperature profile inside the particle and the energy flux from the surroundings to the tyre particles and, finally, a hydrodynamic model that predicts the solid flow pattern inside the reactor. These three sub-models have been integrated in order to develop a comprehensive reactor model. Experimental results were obtained in a continuous moving bed reactor and used to validate model predictions, with good approximation achieved between the experimental and simulated results. In addition, a parametric study of the model was carried out, which showed that tyre particle heating is clearly faster than average particle residence time inside the reactor. Therefore, this fast particle heating together with fast reaction kinetics enables total solid conversion to be achieved in this system in accordance with the predictive model. Copyright © 2010 Elsevier Ltd. All rights reserved.

  15. Orbital Debris Research in the United States

    NASA Technical Reports Server (NTRS)

    Stansbery, Gene

    2009-01-01

    The presentation includes information about growth of the satellite population, the U.S. Space Surveillance Network, tracking and catalog maintenance, Haystack and HAX radar observation, Goldstone radar, the Michigan Orbital Debris Survey Telescope (MODEST), spacecraft surface examinations and sample of space shuttle impacts. GEO/LEO observations from Kwajalein Atoll, NASA s Orbital Debris Engineering Model (ORDEM2008), a LEO-to-GEO Environment Debris Model (LEGEND), Debris Assessment Software (DAS) 2.0, the NASA/JSC BUMPER-II meteoroid/debris threat assessment code, satellite reentry risk assessment, optical size and shape determination, work on more complicated fragments, and spectral studies.

  16. Transformation of dilative and contractive landslide debris into debris flows-An example from marin County, California

    USGS Publications Warehouse

    Fleming, R.W.; Ellen, S.D.; Algus, M.A.

    1989-01-01

    The severe rainstorm of January 3, 4 and 5, 1982, in the San Francisco Bay area, California, produced numerous landslides, many of which transformed into damaging debris flows. The process of transformation was studied in detail at one site where only part of a landslide mobilized into several episodes of debris flow. The focus of our investigation was to learn whether the landslide debris dilated or contracted during the transformation from slide to flow. The landslide debris consisted of sandy colluvium that was separable into three soil horizons that occupied the axis of a small topographic swale. Failure involved the entire thickness of colluvium; however, over parts of the landslide, the soil A-horizon failed separately from the remainder of the colluvium. Undisturbed samples were taken for density measurements from outside the landslide, from the failure zone and overlying material from the part of the landslide that did not mobilize into debris flows, and from the debris-flow deposits. The soil A-horizon was contractive and mobilized to flows in a process analogous to liquefaction of loose, granular soils during earthquakes. The soil B- and C-horizons were dilative and underwent 2 to 5% volumetric expansion during landslide movement that permitted mobilization of debris-flow episodes. Several criteria can be used in the field to differentiate between contractive and dilative behavior including lag time between landsliding and mobilization of flow, episodic mobilization of flows, and partial or complete transformation of the landslide. ?? 1989.

  17. Geochemical stability of phosphorus solids below septic system infiltration beds

    NASA Astrophysics Data System (ADS)

    Zurawsky, M. A.; Robertson, W. D.; Ptacek, C. J.; Schiff, S. L.

    2004-09-01

    Review of 10 mature septic system plumes in Ontario, revealed that phosphorus (P) attenuation commonly occurred close to the infiltration pipes, resulting in discrete narrow intervals enriched in P by a factor of 2-4 ( Wood, J.S.A. 1993. MSc thesis, Dept. Earth Sci., University of Waterloo, Waterloo, Ont.; Ground Water 36 (1995) 1000; J. Contam. Hydrol. 33 (1998) 405). Although these attenuation reactions appeared to be sustainable under present conditions, the potential for remobilization of this P mass, should geochemical conditions change, is unknown. To test the stability of these P solids, dynamic flow column tests were carried out using sediments from three of the previously studied sites (Cambridge, Langton and Muskoka) focusing on sediments from the 'High-P' and underlying (Below) zones. Tests were continued for 166-266 pore volumes (PVs), during which time varying degrees of water saturation were maintained. During saturated flow conditions, relatively high concentrations of PO 4 were eluted from the Cambridge and Langton High-P zones (up to 4 and 9 mg/l P, respectively), accompanied by elevated concentrations of Fe (up to 1.4 mg/l) and Mn (up to 4 mg/l) and lower values of Eh (<150 mV). The Below zones from Cambridge and Langton, however, maintained lower concentrations of P (generally<2 mg/l), Fe (<0.2 mg/l) and Mn (<1 mg/l) and maintained higher Eh (>250 mV) during saturated flow conditions. During unsaturated flow, P and Fe declined dramatically in the High-P zones (P<1 mg/l, Fe<0.2 mg/l), whereas concentrations remained about the same during saturated and unsaturated flow in the Below zones. This behavior is at least partly attributed to the development of reducing conditions during saturated flow in the High-P zones, leading to reductive dissolution of Fe (III)-P solids present in the sediments. Reducing conditions did not develop in the Below zones apparently because of lower sediment organic carbon (OC) contents (0.03-0.04 wt.%) compared to the

  18. Orbital Debris Quarterly News, Volume 13, Issue 4

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi (Editor); Shoots, Debi (Editor)

    2009-01-01

    Although NASA has conducted research on orbital debris since the 1960s, the NASA Orbital Debris Program Office is now considered to have been established in October 1979, following the recognition by senior NASA officials of orbital debris as a space environmental issue and the allocation by NASA Headquarters Advanced Programs Office to the Lyndon B. Johnson Space Center (JSC) of funds specifically dedicated for orbital debris investigations. In the 30 years since, the NASA Orbital Debris Program Office has pioneered the characterization of the orbital debris environment and its potential effects on current and future space systems, has developed comprehensive orbital debris mitigation measures, and has led efforts by the international aerospace community in addressing the challenges posed by orbital debris. In 1967 the Flight Analysis Branch at the Manned Spacecraft Center (renamed the Lyndon B. Johnson Space Center in 1973) evaluated the risks of collisions between an Apollo spacecraft and orbital debris. Three years later the same group calculated collision risks for the forthcoming Skylab space station, which was launched in 1973. By 1976, the nucleus of NASA s yet-to-be-formed orbital debris research efforts, including Andrew Potter, Burton Cour-Palais, and Donald Kessler, was found in JSC s Environmental Effects Office, examining the potential threat of orbital debris to large space platforms, in particular the proposed Solar Power Satellites (SPS).

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

    PubMed

    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.

  20. Active Debris Removal Using Modified Launch Vehicle Upper Stages

    NASA Astrophysics Data System (ADS)

    Nasseri, S. Ali; Emanuelli, Matteo; Raval, Siddharth; Turconi, Andrea

    2013-09-01

    During the past few years, several research programs have assessed the current state and future evolution of space debris in the Low Earth Orbit region. These studies indicate that space debris density could reach a critical level such that there will be a continuous increase in the number of debris objects, primarily driven by debris-debris collision activity known as the Kessler effect. These studies also highlight the urgency for active debris removal.An Active Debris Removal System (ADRS) is capable of approaching the debris object through a close-range rendezvous, stabilizing its attitude, establishing physical contact, and finally de-orbiting the debris object. The de-orbiting phase could be powered by propulsion systems such as chemical rockets or electrodynamic tether (EDT) systems.The aim of this project is to model and evaluate a debris removal mission in which an adapted rocket upper stage, equipped with an electrodynamic tether (EDT) system, is employed for de-orbiting a debris object. This ADRS package is installed initially as part of a launch vehicle on a normal satellite deployment mission, and a far-approach manoeuvre will be required to align the ADRS' orbit with that of the target debris. We begin by selecting a suitable target debris and launch vehicle, and then proceed with modelling the entire debris removal mission from launch to de-orbiting of the target debris object using Analytical Graphic Inc.'s Systems Tool Kit (STK).

  1. Development of the Space Debris Sensor

    NASA Technical Reports Server (NTRS)

    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.

  2. Assessment and prediction of debris-flow hazards

    USGS Publications Warehouse

    Wieczorek, Gerald F.; ,

    1993-01-01

    Study of debris-flow geomorphology and initiation mechanism has led to better understanding of debris-flow processes. This paper reviews how this understanding is used in current techniques for assessment and prediction of debris-flow hazards.

  3. Electrical capacitance volume tomography (ECVT) applied to bubbling fluid beds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Weber, J., Mei, J.

    2012-01-01

    These presentation visuals illustrate the apparatus and method for applying Electrical Capacitance Volume Tomography (ECVT) to bubbling fluid beds to their solid fraction and bubble properties. Results are compared to estimated values.

  4. Multi-stage circulating fluidized bed syngas cooling

    DOEpatents

    Liu, Guohai; Vimalchand, Pannalal; Guan, Xiaofeng; Peng, WanWang

    2016-10-11

    A method and apparatus for cooling hot gas streams in the temperature range 800.degree. C. to 1600.degree. C. using multi-stage circulating fluid bed (CFB) coolers is disclosed. The invention relates to cooling the hot syngas from coal gasifiers in which the hot syngas entrains substances that foul, erode and corrode heat transfer surfaces upon contact in conventional coolers. The hot syngas is cooled by extracting and indirectly transferring heat to heat transfer surfaces with circulating inert solid particles in CFB syngas coolers. The CFB syngas coolers are staged to facilitate generation of steam at multiple conditions and hot boiler feed water that are necessary for power generation in an IGCC process. The multi-stage syngas cooler can include internally circulating fluid bed coolers, externally circulating fluid bed coolers and hybrid coolers that incorporate features of both internally and externally circulating fluid bed coolers. Higher process efficiencies can be realized as the invention can handle hot syngas from various types of gasifiers without the need for a less efficient precooling step.

  5. Solid Surface Combustion Experiment

    NASA Image and Video Library

    1994-09-12

    STS064-10-011 (12 Sept. 1994) --- The Solid Surface Combustion Experiment (SSCE), designed to supply information on flame spread over solid fuel surfaces in the reduced-gravity environment of space, is pictured during flight day four operations. The middeck experiment measured the rate of spreading, the solid-phase temperature, and the gas-phase temperature of flames spreading over rectangular fuel beds. STS-64 marked the seventh trip into space for the Lewis Research Center experiment. Photo credit: NASA or National Aeronautics and Space Administration

  6. Sources of debris flow material in burned areas

    USGS Publications Warehouse

    Santi, P.M.; deWolfe, V.G.; Higgins, J.D.; Cannon, S.H.; Gartner, J.E.

    2008-01-01

    The vulnerability of recently burned areas to debris flows has been well established. Likewise, it has been shown that many, if not most, post-fire debris flows are initiated by runoff and erosion and grow in size through erosion and scour by the moving debris flow, as opposed to landslide-initiated flows with little growth. To better understand the development and character of these flows, a study has been completed encompassing 46 debris flows in California, Utah, and Colorado, in nine different recently burned areas. For each debris flow, progressive debris production was measured at intervals along the length of the channel, and from these measurements graphs were developed showing cumulative volume of debris as a function of channel length. All 46 debris flows showed significant bulking by scour and erosion, with average yield rates for each channel ranging from 0.3 to 9.9??m3 of debris produced for every meter of channel length, with an overall average value of 2.5??m3/m. Significant increases in yield rate partway down the channel were identified in 87% of the channels, with an average of a three-fold increase in yield rate. Yield rates for short reaches of channels (up to several hundred meters) ranged as high as 22.3??m3/m. Debris was contributed from side channels into the main channels for 54% of the flows, with an average of 23% of the total debris coming from those side channels. Rill erosion was identified for 30% of the flows, with rills contributing between 0.1 and 10.5% of the total debris, with an average of 3%. Debris was deposited as levees in 87% of the flows, with most of the deposition occurring in the lower part of the basin. A median value of 10% of the total debris flow was deposited as levees for these cases, with a range from near zero to nearly 100%. These results show that channel erosion and scour are the dominant sources of debris in burned areas, with yield rates increasing significantly partway down the channel. Side channels are

  7. The use of a paper/wood/plastics mixing as a model waste to study the incineration of municipal solid waste in fluidized beds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Desroches-Ducarne, E.; Marty, E.; Martin, G.

    1997-12-31

    Municipal Solid Waste (MSW) incineration in fluidized beds has recently become the subject of intense research. In this paper, the authors chose to elaborate a simple model waste prepared with 4 of the main MSW components (paper, wood, PE, and PVC). The behaviors of typical French MSW and model waste during their combustion in a fluidized bed incinerator were studied. To establish the comparison, the emissions of NO, N{sub 2}O, SO{sub 2} and HCl were investigated. Moreover, experiments were performed according to statistical experimental designs to examine the effect of various operating parameters including bed temperature, excess air, limestone feedingmore » rate and waste moisture. On a qualitative point of view, the impact of the combustion conditions on the pollutants emissions was found to be the same for the two wastes. Bed temperature and excess air have, in both cases, an important impact on NO and N{sub 2}O emissions. Nitrogen oxides production was also directly related to limestone feed content. Very high sulphur and chlorine retention was obtained when limestone was added at much larger excess to the feed. N{sub 2}O emissions are less important during the model waste combustion. The nitrogen functionality seems to give rise to such a phenomenon. In MSW, nitrogen is included in high molecules which is released for a great part as HCN or remains in char, which are the main sources of N{sub 2}O. To confirm this assumption, tests for measuring the HCN/NH{sub 3} ratio for each fuel were performed.« less

  8. The dynamics of coherent flow structures within a submerged permeable bed

    NASA Astrophysics Data System (ADS)

    Blois, G.; Best, J.; Sambrook Smith, G.; Hardy, R. J.; Lead, J.

    2009-12-01

    The existence of complex 3D coherent vortical structures in turbulent boundary layers has been widely reported from experimental observations (Adrian et al., 2007, Christensen and Adrian, 2001) and investigations of natural open channel flows (e.g. Kostaschuk and Church, 1993; Best, 2005). The interaction between these flow structures and the solid boundary that is responsible for their generation is also receiving increasing attention due to the central role played by turbulence in governing erosion-deposition processes. Yet, for the majority of studies, the bed roughness has been represented using rough impermeable surfaces. While not inherently acknowledged, most research in this area is thus only strictly applicable to those natural river beds composed either of bedrock or clay, or that have armoured, impermeable, surfaces. Recently, many researchers have noted the need to account for the role of bed permeability in order to accurately reproduce the true nature of flow over permeable gravel-bed rivers. For these cases, the near-bed flow is inherently and mutually linked to the interstitial-flow occurring in the porous solid matrix. This interaction is established through turbulence mechanisms occurring across the interface that may be important for influencing the incipient motion of cohesionless sediment. However, the nature of this turbulence and the formation of coherent structures within such permeable beds remain substantially unresolved due to the technical challenges of collecting direct data in this region. In this paper, we detail the existence and dynamic nature of coherent vortical structures within the individual pore spaces of a permeable bed submerged by a free stream flow. Laboratory experiments are reported in which a permeable flume bed was constructed using spheres packed in an offset cubic arrangement. We applied a high resolution E-PIV (Endoscopic Particle Image Velocimetry) approach in order to fully resolve the instantaneous structure of

  9. Microchemical Analysis Of Space Operation Debris

    NASA Technical Reports Server (NTRS)

    Cummings, Virginia J.; Kim, Hae Soo

    1995-01-01

    Report discusses techniques used in analyzing debris relative to space shuttle operations. Debris collected from space shuttle, expendable launch vehicles, payloads carried by space shuttle, and payloads carried by expendable launch vehicles. Optical microscopy, scanning electron microscopy with energy-dispersive spectrometry, analytical electron microscopy with wavelength-dispersive spectrometry, and X-ray diffraction chosen as techniques used in examining samples of debris.

  10. Reversed flow fluidized-bed combustion apparatus

    DOEpatents

    Shang, Jer-Yu; Mei, Joseph S.; Wilson, John S.

    1984-01-01

    The present invention is directed to a fluidized-bed combustion apparatus provided with a U-shaped combustion zone. A cyclone is disposed in the combustion zone for recycling solid particulate material. The combustion zone configuration and the recycling feature provide relatively long residence times and low freeboard heights to maximize combustion of combustible material, reduce nitrogen oxides, and enhance sulfur oxide reduction.

  11. Space Debris Environment Remediation Concepts

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.; Klinkrad, Heiner

    2009-01-01

    Long-term projections of the space debris environment indicate that even drastic measures, such as an immediate, complete halt of launch and release activities, will not result in a stable environment of man-made space objects. Collision events between already existing space hardware will within a few decades start to dominate the debris population, and result in a net increase of the space debris population, also in size regimes which may cause further catastrophic collisions. Such a collisional cascading will ultimately lead to a run-away situation ("Kessler syndrome"), with no further possibility of human intervention. The International Academy of Astronautics (IAA) has been investigating the status and the stability of the space debris environment in several studies by first looking into space traffic management possibilities and then investigating means of mitigating the creation of space debris. In an ongoing activity, an IAA study group looks at ways of active space debris environment remediation. In contrast to the former mitigation study, the current activity concentrates on the active removal of small and large objects, such as defunct spacecraft, orbital stages, and mission-related objects, which serve as a latent mass reservoir that fuels initial catastrophic collisions and later collisional cascading. The paper will outline different mass removal concepts, e.g. based on directed energy, tethers (momentum exchange or electrodynamic), aerodynamic drag augmentation, solar sails, auxiliary propulsion units, retarding surfaces, or on-orbit capture. Apart from physical principles of the proposed concepts, their applicability to different orbital regimes, and their effectiveness concerning mass removal efficiency will be analyzed. The IAA activity on space debris environment remediation is a truly international project which involves more than 23 contributing authors from 9 different nations.

  12. The impact of debris on marine life.

    PubMed

    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.

  13. Orifice plate for controlling solids flow, methods of use thereof and articles comprising the same

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jukkola, Glen D.; Teigen, Bard C.

    Disclosed herein is an orifice plate comprising one or more plates having orifices disposed therein; the orifices being operative to permit the flow of solids from a moving bed heat exchanger to a solids flow control system; where the orifice plate is downstream of a tube bundle of the moving bed heat exchanger and upstream of the solids flow control system and wherein the orifice plate is operative to evenly distribute the flow of solids in the solids flow control system.

  14. Development of the Space Debris Sensor (SDS)

    NASA Technical Reports Server (NTRS)

    Hamilton, Joe; Liou, J. -C.; Anz-Meador, P.; Matney, M.; Christiansen, E.

    2017-01-01

    Debris Resistive/Acoustic Grid Orbital Navy-NASA Sensor (DRAGONS) is an impact sensor designed to detect and characterize collisions with small orbital debris: from 50 microns to greater than 1millimeter debris size detection; Characterizes debris size, speed, direction, and density. The Space Debris Sensor (SDS) is a flight demonstration of DRAGONS on the International Space Station: Approximately 1 square meter of detection area facing the ISS velocity vector; Minimum two year mission on Columbus External Payloads Facility (EPF); Minimal obstruction from ISS hardware; Development is nearing final checkout and integration with the ISS; Current launch schedule is SpaceX13, about September 2017, or SpaceX14, about Jan 2018.

  15. Ingestion of marine debris by the White-chinned Petrel (Procellaria aequinoctialis): Is it increasing over time off southern Brazil?

    PubMed

    Petry, Maria V; Benemann, Victória R F

    2017-04-15

    Seabirds are amongst the most affected organisms by plastic pollution worldwide. Ingestion of marine debris has been reported in at least 122 species, and owing to the increasing global production and persistence of these anthropogenic materials within the marine environment, it is expected to be a growing problem to the marine fauna. Here we report evidence of an increasing frequency in marine debris ingestion and a decrease in the amount of plastic pellets ingested by White-chinned Petrels attending south Brazilian waters during the last three decades. Future studies comprising large temporal scales and large sample sizes are needed to better understand the trends of marine debris ingestion by seabirds. We expect our findings to highlight the need for prevention policies and mitigation measures to reduce the amount of solid litter in the oceans. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Conceptual design of an Orbital Debris Defense System

    NASA Technical Reports Server (NTRS)

    Bedillion, Erik; Blevins, Gary; Bohs, Brian; Bragg, David; Brown, Christopher; Casanova, Jose; Cribbs, David; Demko, Richard; Henry, Brian; James, Kelly

    1994-01-01

    Man made orbital debris has become a serious problem. Currently NORAD tracks over 7000 objects in orbit and less than 10 percent of these are active payloads. Common estimates are that the amount of debris will increase at a rate of 10 percent per year. Impacts of space debris with operational payloads or vehicles is a serious risk to human safety and mission success. For example, the impact of a 0.2 mm diameter paint fleck with the Space Shuttle Challenger window created a 2 mm wide by 0.6 mm deep pit. The cost to replace the window was over $50,000. A conceptual design for a Orbital Debris Defense System (ODDS) is presented which considers a wide range of debris sizes, orbits and velocities. Two vehicles were designed to collect and remove space debris. The first would attach a re-entry package to de-orbit very large debris, e.g. inactive satellites and spent upper stages that tend to break up and form small debris. This vehicle was designed to contain several re-entry packages, and be refueled and resupplied with more re-entry packages as needed. The second vehicle was designed to rendezvous with and capture debris ranging from 10 cm to 2 m. Due to tracking limitations, no technically feasible method for collecting debris below 10 cm in size could be devised; it must be accomplished through international regulations which reduce the accumulation of space debris.

  17. Space Transportation System Liftoff Debris Mitigation Process Overview

    NASA Technical Reports Server (NTRS)

    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. Influence of fishing activity over the marine debris composition close to coastal jetty.

    PubMed

    Farias, Eduardo G G; Preichardt, Paulo R; Dantas, David V

    2018-04-23

    Worldwide, the marine debris emissions have been provoking impacts in ecosystems, generating massive mortality of different species with commercial interest. In South America, we have a lack of studies to verify the marine debris composition in transitional environments such as adjacent regions of coastal jetties. These are hydraulic engineering constructions used to maintain the navigation channel access between the sea-estuarine interface and are also used by teleost fishes, crustaceans, and mollusks like artificial shelters (reefs), being excellent fishing grounds. Therefore, the present study was devoted to qualitatively evaluate the composition of marine debris in an internal jetty portion of a Laguna Estuarine System (LES) located in South America (Brazil). Six hundred freediving were conducted to collect marine debris in the study region. The in situ campaigns were performed in 2016 during all spring season (sand substrata) in four distinct zones with 26,400 m 2 each one covering almost all adjacent jetty extension, to evaluate possible spatial changes in the marine debris composition. All material obtained was identified, measured, weighed, and ordered in eight groups, with six groups being related to the fishing activity and two groups related to the tourism/community in the study region. So, it was possible to observe possible relations between the marine debris distribution to artisanal and recreational local fishing. After 600 freediving sampling efforts, 2142 marine debris items were obtained, totaling close to 100 kg of solid waste removed from the inner portion of the coastal jetty. Notably, 1752 units (50 kg) of fishing leads were collected being this item the main marine debris residue found in the four sampled areas, corresponding to nearly 50% of the total weight of the collected waste. Ninety-eight percent of marine debris were derived from the local fishing activities, and just 2% were derived from tourism/community. Considering the total

  19. Debris ingestion by juvenile marine turtles: an underestimated problem.

    PubMed

    Santos, Robson Guimarães; Andrades, Ryan; Boldrini, Marcillo Altoé; Martins, Agnaldo Silva

    2015-04-15

    Marine turtles are an iconic group of endangered animals threatened by debris ingestion. However, key aspects related to debris ingestion are still poorly known, including its effects on mortality and the original use of the ingested debris. Therefore, we analysed the impact of debris ingestion in 265 green turtles (Chelonia mydas) over a large geographical area and different habitats along the Brazilian coast. We determined the death rate due to debris ingestion and quantified the amount of debris that is sufficient to cause the death of juvenile green turtles. Additionally, we investigated the original use of the ingested debris. We found that a surprisingly small amount of debris was sufficient to block the digestive tract and cause death. We suggested that debris ingestion has a high death potential that may be masked by other causes of death. An expressive part of the ingested debris come from disposable and short-lived products. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. A lagrangian-eulerian description of debris transport by a tsunami in the Lisbon waterfront

    NASA Astrophysics Data System (ADS)

    Conde, Daniel; Canelas, Ricardo; Baptista, Maria Ana; João Telhado, Maria; Ferreira, Rui M. L.

    2013-04-01

    Several major tsunamis are known to have struck the Portuguese coast over the past millennia (Baptista and Miranda, 2009). The Tagus estuary has great exposure to tsunami occurrences and, being bordered by the largest metropolitan area in the country, is a particularly worrisome location in what concerns safety of populations and economic losses due to disruption of built infrastructures. The last major earthquake and tsunami combination known to have critically affected the Tagus estuary dates back to November 1st 1755. This catastrophe critically damaged Lisbon's infrastructures, led to numerous casualties and priceless heritage losses. The urban tissue of the present city still bears visible the effects of the catastrophe and of the ensuing protection measures. The objective of this work is to simulate the propagation of debris carried by a 1755-like tsunami along the present-day bathimetric and altimetric conditions of Lisbon waterfront. Particular emphasis was directed to the modeling of vehicles since the tsunami is likely to affect areas that are major traffic nodes such as Alcântara, with more than 1500 vehicles in road network of about 3 km. The simulation tool employed is based on a 2DH spatial (eulerian) shallow-flow approach suited to complex and dynamic bottom boundaries. The discretization technique relies on a finite-volume scheme, based on a flux-splitting technique incorporating a reviewed version of the Roe Riemann solver (Canelas et al. 2013). Two formulations were employed to model the advection of debris: a fully coupled continuum approach, where solid bodies are described by the concentration only and an uncoupled material (lagrangian) formulation where solid bodies are tracked between two time-steps once the flow field is determined by the eulerian solver. In the latter case, concentrations are updated after tracking the solid bodies thus correcting the mass and momentum balance to be used for the next time-step. The urban tissue was

  1. Activities on Space Debris in U.S.

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2001-01-01

    In the U.S. space debris activities are addressed at all government levels, from the Executive Office of the President to the individual federal agencies to specialized centers, laboratories, organizations, and research groups. U.S. Space Policy specifically challenges government agencies to seek to minimize the creation of space debris and to promote debris minimization practices both domestically and internationally. A set of space debris mitigation standard practices has been developed and adopted by relevant US government agencies, and their application by the commercial aerospace community is highly encouraged. A growing number of US government agencies have issued their own space debris mitigation policies, directives, regulations, and standards. Space debris research, including the definition and modeling of the current and future near-Earth space environment and the development of debris protection technologies, is principally conducted by NASA and the Department of Defense. The U.S. Space Surveillance Network continues to provide the most complete and timely characterization of the population of space debris larger than 10 cm. During the past several years major advancements have been achieved in extending this environment definition in LEO to include particles as small as only a few millimeters. The inspection of returned spacecraft surfaces continues to shed light on the even smaller debris population. With improvements in computer technology, new and more capable programs have been and are being developed to solve a number of operational and research problems. Finally, the academic and industrial sectors of the U.S. are also increasing their participation in and contributions to space debris operations and research. The cooperation of satellite and launch vehicle developers and operators is essential to the U.S. objective of promoting the preservation of the space environment for future generations.

  2. Activities on space debris in U.S.

    NASA Astrophysics Data System (ADS)

    Johnson, Nicholas L.

    2001-10-01

    In the U.S. space debris activities are addressed at all government levels, from the Executive Office of the President to the individual federal agencies to specialized centers, laboratories, organizations, and research groups. U.S. Space Policy specifically challenges government agencies to seek to minimize the creation of space debris and to promote debris minimization practices, both domestically and internationally. A set of space debris mitigation standard practices has been developed and adopted by relevant U.S. government agencies, and their application by the commercial aerospace community is highly encouraged. A growing number of U.S. government agencies have issued their own space debris mitigation policies, directives, regulations, and standards. Space debris research, including the definition and modeling of the current and future near-Earth space environment and the development of debris protection technologies, is principally conducted by NASA and the Department of Defense. The U.S. Space Surveillance Network continues to provide the most complete and timely characterization of the population of space debris larger than 10 cm. During the past several years major advancements have been achieved in extending this environment definition in LEO to include particles as small as only a few millimeters. The inspection of returned spacecraft surfaces continues to shed light on the even smaller debris population. With improvements in computer technology, new and more capable programs have been and are being developed to solve a number of operational and research problems. Finally, the academic and industrial sectors of the U.S. are also increasing their participation in and contributions to space debris operations and research. The cooperation of spacecraft and launch vehicle developers and operators is essential to the U.S. objective of promoting the preservation of the space environment for future generations.

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

    PubMed

    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.

  4. Acoustic bed velocity and bed load dynamics in a large sand bed river

    USGS Publications Warehouse

    Gaeuman, D.; Jacobson, R.B.

    2006-01-01

    Development of a practical technology for rapid quantification of bed load transport in large rivers would represent a revolutionary advance for sediment monitoring and the investigation of fluvial dynamics. Measurement of bed load motion with acoustic Doppler current profiles (ADCPs) has emerged as a promising approach for evaluating bed load transport. However, a better understanding of how ADCP data relate to conditions near the stream bed is necessary to make the method practical for quantitative applications. In this paper, we discuss the response of ADCP bed velocity measurements, defined as the near-bed sediment velocity detected by the instrument's bottom-tracking feature, to changing sediment-transporting conditions in the lower Missouri River. Bed velocity represents a weighted average of backscatter from moving bed load particles and spectral reflections from the immobile bed. The ratio of bed velocity to mean bed load particle velocity depends on the concentration of the particles moving in the bed load layer, the bed load layer thickness, and the backscatter strength from a unit area of moving particles relative to the echo strength from a unit area of unobstructed bed. A model based on existing bed load transport theory predicted measured bed velocities from hydraulic and grain size measurements with reasonable success. Bed velocities become more variable and increase more rapidly with shear stress when the transport stage, defined as the ratio of skin friction to the critical shear stress for particle entrainment, exceeds a threshold of about 17. This transition in bed velocity response appears to be associated with the appearance of longer, flatter bed forms at high transport stages.

  5. Carrier effects on tertiary nitrifying moving bed biofilm reactor: An examination of performance, biofilm and biologically produced solids.

    PubMed

    Forrest, Daina; Delatolla, Robert; Kennedy, Kevin

    2016-01-01

    Increasingly stricter ammonia and nitrogen release regulations with respect to wastewater effluents are creating a need for tertiary treatment systems. The moving bed biofilm reactor (MBBR) is being considered as an upgrade option for an increasing number of wastewater treatment facilities due to its small footprint and ease of operation. Despite the MBBRs creation as a system to remove nitrogen, recent research on MBBR systems showing that the system's performance is directly related to carrier surface area and is irrespective of carrier shape and type has been performed exclusively on chemical oxygen demand (COD) removal systems. Furthermore, the influence of carrier type on the solids produced by MBBR systems has also been exclusively studied for COD removal systems. This work investigates the effects of three specific carrier types on ammonia removal rates, biofilm morphology, along with solids production and settleability of tertiary nitrifying MBBR systems. The study concludes that carrier type has no significant effect on tertiary nitrifying MBBR system performance under steady, moderate loading conditions. The research does however highlight the propensity of greater surface area to volume carriers to become clogged under high loading conditions and that the high surface area carriers investigated in this study required longer adjustment periods to changes in loading after becoming clogged.

  6. Comparison of coal/solid recovered fuel (SRF) with coal/refuse derived fuel (RDF) in a fluidised bed reactor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wagland, S.T.; Kilgallon, P.; Coveney, R.

    2011-06-15

    An experimental study was undertaken to compare the differences between municipal solid waste (MSW) derived solid recovered fuel (SRF) (complying with CEN standards) and refuse derived fuel (RDF). Both fuels were co-combusted with coal in a 50 kW fluidised bed combustor and the metal emissions were compared. Synthetic SRF was prepared in the laboratory by grinding major constituents of MSW such as paper, plastic, textile and wood. RDF was obtained from a local mechanical treatment plant. Heavy metal emissions in flue gas and ash samples from the (coal + 10% SRF) fuel mixture were found to be within the acceptablemore » range and were generally lower than that obtained for coal + 10% RDF fuel mixture. The relative distribution of heavy metals in ash components and the flue gas stream shows the presence of a large fraction (up to 98%) of most of the metals in the ash (except Hg and As). Thermo-gravimetric (TG) analysis of SRF constituents was performed to understand the behaviour of fuel mixtures in the absence and presence of air. The results obtained from the experimental study will enhance the confidence of fuel users towards using MSW-derived SRF as an alternative fuel.« less

  7. Structure of the Iconic Vega Debris Disk

    NASA Astrophysics Data System (ADS)

    Su, Kate

    2015-10-01

    Debris structures provide the best means to explore planets down to ice-giant masses in the outer (>5 AU) parts of extrasolar planetary systems. It is thought that the iconic Vega debris disk composes of two separate belts shepherded by unseen planets, similar to the Solar System. We will probe this possibility with SOFIA at 35 microns by: 1.) documenting the structure of the debris with sufficient resolution to distinguish a separate warm belt from the alternative model of dust flowing inward from the outer debris ring; and 2.) testing for traces of dust in its 15-60 AU zone and thus probing the possibility that ice giant planets may be shepherding the debris belts.

  8. Comparison of debris flux models

    NASA Astrophysics Data System (ADS)

    Sdunnus, H.; Beltrami, P.; Klinkrad, H.; Matney, M.; Nazarenko, A.; Wegener, P.

    The availability of models to estimate the impact risk from the man-made space debris and the natural meteoroid environment is essential for both, manned and unmanned satellite missions. Various independent tools based on different approaches have been developed in the past years. Due to an increased knowledge of the debris environment and its sources e.g. from improved measurement capabilities, these models could be updated regularly, providing more detailed and more reliable simulations. This paper addresses an in-depth, quantitative comparison of widely distributed debris flux models which were recently updated, namely ESA's MASTER 2001 model, NASA's ORDEM 2000 and the Russian SDPA 2000 model. The comparison was performed in the frame of the work of the 20t h Interagency Debris Coordination (IADC) meeting held in Surrey, UK. ORDEM 2000ORDEM 2000 uses careful empirical estimates of the orbit populations based onthree primary data sources - the US Space Command Catalog, the H ystackaRadar, and the Long Duration Exposure Facility spacecraft returned surfaces.Further data (e.g. HAX and Goldstone radars, impacts on Shuttle windows andradiators, and others) were used to adjust these populations for regions in time,size, and space not covered by the primary data sets. Some interpolation andextrapolation to regions with no data (such as projections into the future) wasprovided by the EVOLVE model. MASTER 2001The ESA MASTER model offers a full three dimensional description of theterrestrial debris distribution reaching from LEO up to the GEO region. Fluxresults relative to an orbiting target or to an inertial volume can be resolved intosource terms, impactor characteristics and orbit, as well as impact velocity anddirection. All relevant debris source terms are considered by the MASTERmodel. For each simulated source, a corresponding debris generation model interms of mass/diameter distribution, additional velocities, and directionalspreading has been developed. A

  9. NASA Orbital Debris Baseline Populations

    NASA Technical Reports Server (NTRS)

    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.

  10. DebriSat Project Update and Planning

    NASA Technical Reports Server (NTRS)

    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.

  11. Semi-automatic recognition of marine debris on beaches

    PubMed Central

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

    2016-01-01

    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. PMID:27156433

  12. Semi-automatic recognition of marine debris on beaches

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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.

  13. Simulations of SSLV Ascent and Debris Transport

    NASA Technical Reports Server (NTRS)

    Rogers, Stuart; Aftosmis, Michael; Murman, Scott; Chan, William; Gomez, Ray; Gomez, Ray; Vicker, Darby; Stuart, Phil

    2006-01-01

    A viewgraph presentation on Computational Fluid Dynamic (CFD) Simulation of Space Shuttle Launch Vehicle (SSLV) ascent and debris transport analysis is shown. The topics include: 1) CFD simulations of the Space Shuttle Launch Vehicle ascent; 2) Debris transport analysis; 3) Debris aerodynamic modeling; and 4) Other applications.

  14. Mitigation of Debris Flow Damage--­ A Case Study of Debris Flow Damage

    NASA Astrophysics Data System (ADS)

    Lin, J. C.; Jen, C. H.

    Typhoon Toraji caused more than 30 casualties in Central Taiwan on the 31st July 2001. It was the biggest Typhoon since the Chi-Chi earthquake of 1999 with huge amounts of rainfall. Because of the influence of the earthquake, loose debris falls and flows became major hazards in Central Taiwan. Analysis of rainfall data and sites of slope failure show that damage from these natural hazards were enhanced as a result of the Chi-Chi earthquake. Three main types of hazard occurred in Central Taiwan: land- slides, debris flows and gully erosion. Landslides occurred mainly along hill slopes and banks of channels. Many dams and houses were destroyed by flooding. Debris flows occurred during typhoon periods and re-activated ancient debris depositions. Many new gullies were therefore developed from deposits loosened and shaken by the earthquake. This paper demonstrates the geological/geomorphological background of the hazard area, and reviews methods of damage mitigation in central Taiwan. A good example is Hsi-Tou, which had experienced no gully erosion for more than 40 years. The area experienced much gully erosion as a result of the combined effects of earth- quake and typhoon. Although Typhoon Toraji produced only 30% of the rainfall of Typhoon Herb of 1996, it caused more damage in the Hsi-Tou area. The mitigation of debris flow hazards in Hsi-tou area is discussed in this paper.

  15. Orbital Debris Shape Characterization Project Abstract

    NASA Technical Reports Server (NTRS)

    Pease, Jessie

    2016-01-01

    I have been working on a project to further our understanding of orbital debris by helping create a new dataset previously too complex to be implemented in past orbital debris propagation models. I am doing this by creating documentation and 3D examples and illustrations of the shape categories. Earlier models assumed all orbital debris to be spherical aluminum fragments. My project will help expand our knowledge of shape populations to 6 categories: Straight Needle/Rod/Cylinder, Bent Needle/Rod/Cylinder, Flat Plate, Bent Plate, Nugget/Parallelepiped/Spheroid, and Flexible. The last category, Flexible, is still up for discussion and may be modified. These categories will be used to characterize fragments in the DebriSat experiment.

  16. Arroyo el Mimbral, Mexico, K/T unit: Origin as debris flow/turbidite, not a tsunami deposit

    NASA Technical Reports Server (NTRS)

    Bohor, Bruce F.; Betterton, William J.

    1993-01-01

    Coarse, spherule-bearing, elastic units have been discovered at 10 marine sites that span the K/T boundary in northeastern Mexico. We examined one of the best exposed sites in Arroyo el Mimbral, northwest of Tampico. The Mimbral outcrop displays a layered elastic unit up to 3 m thick enclosed by marly limestones of the Mendez (Latest Maastrichian) and Velasco (Earliest Danian) Formations. At its thickest point, this channelized elastic unit is comprised of 3 subunits: (1) a basal, poorly-sorted, ungraded calcareous spherule bed 1 m thick containing relict impact glass and shocked mineral grains, (2) a massive set of laminated calcite-cemented sandstones up to 2 m thick with plant debris at its base, (3) capped by a thin (up to 20 cm) set of rippled sandstone layers separated by silty mudstone drapes containing a small (921 pg/g) iridium anomaly. This tripartite elastic unit is conformably overlain by marls of the Velasco Formation. We also visited the La Lajilla site east of Ciudad Victoria; its stratigraphy is similar to Mimbral's, but its elastic beds are thinner and less extensive laterally. The Mimbral elastic unit has been interpreted previously as being deposited by a megawave or tsunami produced by an asteroid impact on nearby Yucatan (Chicxulub crater). However, a presumed 400-m paleodepth of water at the Mimbral site, channeling of the spherule subunit into the underlying Mendez Formation marls, and the overtopping of the basal, spherule-bearing subunit by the laminated sandstone subunit, all suggest a combined debris flow/turbidite origin for this elastic unit similar to that proposed for Upper Pleistocene sand/silt beds occurring elsewhere in the Gulf of Mexico. In this latter model, the sediment source region for the elastic unit is the lower continental shelf and slope escarpment. For the K/T unit at Mimbral, we propose that thick ejecta blanket deposits composed mostly of spherules were rapidly loaded onto the lower shelf and slope from an impact

  17. Assessment of Debris Flow Hazards, North Mountain, Phoenix, AZ

    NASA Astrophysics Data System (ADS)

    Reavis, K. J.; Wasklewicz, T. A.

    2014-12-01

    Urban sprawl in many western U.S. cities has expanded development onto alluvial fans. In the case of metropolitan Phoenix, AZ (MPA), urban sprawl has led to an exponential outward growth into surrounding mountainous areas and onto alluvial fans. Building on alluvial fans places humans at greater risk to flooding and debris flow hazards. Recent research has shown debris flows often supply large quantities of material to many alluvial fans in MPA. However, the risk of debris flows to built environments is relatively unknown. We use a 2D debris flow modeling approach, aided by high-resolution airborne LiDAR and terrestrial laser scanning (TLS) topographic data, to examine debris flow behavior in a densely populated portion of the MPA to assess the risk and vulnerability of debris flow damage to the built infrastructure. A calibrated 2D debris flow model is developed for a "known" recent debris flow at an undeveloped site in MPA. The calibrated model and two other model scenarios are applied to a populated area with historical evidence of debris flow activity. Results from the modeled scenarios show evidence of debris flow damage to houses built on the alluvial fan. Debris flow inundation is also evident on streets on the fan. We use housing values and building damage to estimate the costs assocaited with various modeled debris flow scenarios.

  18. Detection of Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, P.; Lederer, S.; Barker, E.; Cowardin, H.; Abercromby, K.; Silha, J.; Burkhardt, A.

    2014-01-01

    There have been extensive optical surveys for debris at geosynchronous orbit (GEO) conducted with meter-class telescopes, such as those conducted with MODEST (the Michigan Orbital DEbris Survey Telescope, a 0.6-m telescope located at Cerro Tololo in Chile), and the European Space Agency's 1.0-m space debris telescope (SDT) in the Canary Islands. These surveys have detection limits in the range of 18th or 19th magnitude, which corresponds to sizes larger than 10 cm assuming an albedo of 0.175. All of these surveys reveal a substantial population of objects fainter than R = 15th magnitude that are not in the public U.S. Satellite Catalog. To detect objects fainter than 20th magnitude (and presumably smaller than 10 cm) in the visible requires a larger telescope and excellent imaging conditions. This combination is available in Chile. NASA's Orbital Debris Program Office has begun collecting orbital debris observations with the 6.5-m (21.3-ft diameter) "Walter Baade" Magellan telescope at Las Campanas Observatory. The goal is to detect objects as faint as possible from a ground-based observatory and begin to understand the brightness distribution of GEO debris fainter than R = 20th magnitude.

  19. Fluidized bed coupled rotary reactor for nanoparticles coating via atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Duan, Chen-Long; Liu, Xiao; Shan, Bin; Chen, Rong

    2015-07-01

    A fluidized bed coupled rotary reactor has been designed for coating on nanoparticles (NPs) via atomic layer deposition. It consists of five major parts: reaction chamber, dosing and fluidizing section, pumping section, rotary manipulator components, as well as a double-layer cartridge for the storage of particles. In the deposition procedure, continuous fluidization of particles enlarges and homogenizes the void fraction in the particle bed, while rotation enhances the gas-solid interactions to stabilize fluidization. The particle cartridge presented here enables both the fluidization and rotation acting on the particle bed, demonstrated by the analysis of pressure drop. Moreover, enlarged interstitials and intense gas-solid contact under sufficient fluidizing velocity and proper rotation speed facilitate the precursor delivery throughout the particle bed and consequently provide a fast coating process. The cartridge can ensure precursors flowing through the particle bed exclusively to achieve high utilization without static exposure operation. By optimizing superficial gas velocities and rotation speeds, minimum pulse time for complete coating has been shortened in experiment, and in situ mass spectrometry showed the precursor usage can reach 90%. Inductively coupled plasma-optical emission spectroscopy results suggested a saturated growth of nanoscale Al2O3 films on spherical SiO2 NPs. Finally, the uniformity and composition of the shells were characterized by high angle annular dark field-transmission electron microscopy and energy dispersive X-ray spectroscopy.

  20. Quantitative assessment of apical debris extrusion and intracanal debris in the apical third, using hand instrumentation and three rotary instrumentation systems.

    PubMed

    H K, Sowmya; T S, Subhash; Goel, Beena Rani; T N, Nandini; Bhandi, Shilpa H

    2014-02-01

    Decreased apical extrusion of debris and apical one third debris have strong implications for decreased incidence of postoperative inflammation and pain. Thus, the aim of this study was to assess quantitatively the apical extrusion of debris and intracanal debris in the apical third during root canal instrumentation using hand and three different types of rotary instruments. Sixty freshly extracted single rooted human teeth were randomly divided into four groups. Canal preparation was done using step-back with hand instrumentation, crown-down technique with respect to ProTaper and K3, and hybrid technique with LightSpeed LSX. Irrigation was done with NaOCl, EDTA, and normal saline and for final irrigation, EndoVac system was used. The apically extruded debris was collected on the pre-weighed Millipore plastic filter disk and weighed using microbalance. The teeth were submitted to the histological processing. Sections from the apical third were analyzed by a trinocular research microscope that was coupled to a computer where the images were captured and analyzed using image proplus V4.1.0.0 software. The mean weight of extruded debris for each group and intracanal debris in the root canal was statistically analyzed by a Kruskal-Wallis one-way analysis of variance and Mann-Whitney U test. The result showed that, hand instrumentation using K files showed the highest amount of debris extrusion apically when compared to ProTaper, K3 and LightSpeed LSX. The result also showed that there was no statistically significant difference between the groups in relation to presence of intracanal debris in the apical one third. Based on the results, all instrumentation techniques produced debris extrusion. The engine driven Ni-Ti systems extruded significantly less apical debris than hand instrumentation. There was no statistically significant difference between the groups in relation to presence of intracanal debris in the apical one third.

  1. Regional danger assessment of Debris flow and its engineering mitigation practice in Sichuan-Tibet highway

    NASA Astrophysics Data System (ADS)

    Su, Pengcheng; Sun, Zhengchao; li, Yong

    2017-04-01

    Luding-Kangding highway cross the eastern edge of Qinghai-Tibet Plateau where belong to the most deep canyon area of plateau and mountains in western Sichuan with high mountain and steep slope. This area belongs to the intersection among Xianshuihe, Longmenshan and Anninghe fault zones which are best known in Sichuan province. In the region, seismic intensity is with high frequency and strength, new tectonic movement is strong, rock is cracked, there are much loose solid materials. Debris flow disaster is well developed under the multiple effects of the earthquake, strong rainfall and human activity which poses a great threat to the local people's life and property security. So this paper chooses Kangding and LuDing as the study area to do the debris flow hazard assessment through the in-depth analysis of development characteristics and formation mechanism of debris flow. Which can provide important evidence for local disaster assessment and early warning forecast. It also has the important scientific significance and practical value to safeguard the people's life and property safety and the security implementation of the national major project. In this article, occurrence mechanism of debris flow disasters in the study area is explored, factor of evaluation with high impact to debris flow hazards is identified, the database of initial evaluation factors is made by the evaluation unit of basin. The factors with high impact to hazards occurrence are selected by using the stepwise regression method of logistic regression model, at the same time the factors with low impact are eliminated, then the hazard evaluation factor system of debris flow is determined in the study area. Then every factors of evaluation factor system are quantified, and the weights of all evaluation factors are determined by using the analysis of stepwise regression. The debris flows hazard assessment and regionalization of all the whole study area are achieved eventually after establishing the

  2. Millimeter Studies of Nearby Debris Disks

    NASA Astrophysics Data System (ADS)

    MacGregor, Meredith Ann

    2017-03-01

    At least 20% of nearby main sequence stars are known to be surrounded by disks of dusty material resulting from the collisional erosion of planetesimals, similar to asteroids and comets in our own Solar System. The material in these ‘debris disks’ is directly linked to the larger bodies, like planets, in the system through collisions and gravitational perturbations. Observations at millimeter wavelengths are especially critical to our understanding of these systems, since the large grains that dominate emission at these long wavelengths reliably trace the underlying planetesimal distribution. In this thesis, I have used state-of-the-art observations at millimeter wavelengths to address three related questions concerning debris disks and planetary system evolution: 1) How are wide-separation, substellar companions formed? 2) What is the physical nature of the collisional process in debris disks? And, 3) Can the structure and morphology of debris disks provide probes of planet formation and subsequent dynamical evolution? Using ALMA observations of GQ Lup, a pre-main sequence system with a wide-separation, substellar companion, I have placed constraints on the mass of a circumplanetary disk around the companion, informing formation scenarios for this and other similar systems (Chapter 2). I obtained observations of a sample of fifteen debris disks with both the VLA and ATCA at centimeter wavelengths, and robustly determined the millimeter spectral index of each disk and thus the slope of the grain size distribution, providing the first observational test of collision models of debris disks (Chapter 3). By applying an MCMC modeling framework to resolved millimeter observations with ALMA and SMA, I have placed the first constraints on the position, width, surface density gradient, and any asymmetric structure of the AU Mic, HD 15115, Epsilon Eridani, Tau Ceti, and Fomalhaut debris disks (Chapters 4–8). These observations of individual systems hint at trends in

  3. Experimental Study and CFD Simulation of a 2D Circulating Fluidized Bed

    NASA Astrophysics Data System (ADS)

    Kallio, S.; Guldén, M.; Hermanson, A.

    Computational fluid dynamics (CFD) gains popularity in fluidized bed modeling. For model validation, there is a need of detailed measurements under well-defined conditions. In the present study, experiments were carried out in a 40 em wide and 3 m high 2D circulating fluidized bed. Two experiments were simulated by means of the Eulerian multiphase models of the Fluent CFD software. The vertical pressure and solids volume fraction profiles and the solids circulation rate obtained from the simulation were compared to the experimental results. In addition, lateral volume fraction profiles could be compared. The simulated CFB flow patterns and the profiles obtained from simulations were in general in a good agreement with the experimental results.

  4. Influence of Rack Design and Disease Prevalence on Detection of Rodent Pathogens in Exhaust Debris Samples from Individually Ventilated Caging Systems.

    PubMed

    Bauer, Beth A; Besch-Williford, Cynthia; Livingston, Robert S; Crim, Marcus J; Riley, Lela K; Myles, Matthew H

    2016-11-01

    Sampling of bedding debris within the exhaust systems of ventilated racks may be a mechanism for detecting murine pathogens in colony animals. This study examined the effectiveness of detecting pathogens by PCR analysis of exhaust debris samples collected from ventilated racks of 2 different rack designs, one with unfiltered air flow from within the cage to the air-exhaust pathway, and the other had a filter between the cage and the air-exhaust pathway. For 12 wk, racks were populated with either 1 or 5 cages of mice (3 mice per cage) infected with one of the following pathogens: mouse norovirus (MNV), mouse parvovirus (MPV), mouse hepatitis virus (MHV), Helicobacter spp., Pasteurella pneumotropica, pinworms, Entamoeba muris, Tritrichomonas muris, and fur mites. Pathogen shedding by infected mice was monitored throughout the study. In the filter-containing rack, PCR testing of exhaust plenums yielded negative results for all pathogens at all time points of the study. In the rack with open air flow, pathogens detected by PCR analysis of exhaust debris included MHV, Helicobacter spp., P. pneumotropica, pinworms, enteric protozoa, and fur mites; these pathogens were detected in racks housing either 1 or 5 cages of infected mice. Neither MPV nor MNV was detected in exhaust debris, even though prolonged viral shedding was confirmed. These results demonstrate that testing rack exhaust debris from racks with unfiltered air flow detected MHV, enteric bacteria and parasites, and fur mites. However, this method failed to reliably detect MNV or MPV infection of colony animals.

  5. Influence of Rack Design and Disease Prevalence on Detection of Rodent Pathogens in Exhaust Debris Samples from Individually Ventilated Caging Systems

    PubMed Central

    Bauer, Beth A; Besch-Williford, Cynthia; Livingston, Robert S; Crim, Marcus J; Riley, Lela K; Myles, Matthew H

    2016-01-01

    Sampling of bedding debris within the exhaust systems of ventilated racks may be a mechanism for detecting murine pathogens in colony animals. This study examined the effectiveness of detecting pathogens by PCR analysis of exhaust debris samples collected from ventilated racks of 2 different rack designs, one with unfiltered air flow from within the cage to the air-exhaust pathway, and the other had a filter between the cage and the air-exhaust pathway. For 12 wk, racks were populated with either 1 or 5 cages of mice (3 mice per cage) infected with one of the following pathogens: mouse norovirus (MNV), mouse parvovirus (MPV), mouse hepatitis virus (MHV), Helicobacter spp., Pasteurella pneumotropica, pinworms, Entamoeba muris, Tritrichomonas muris, and fur mites. Pathogen shedding by infected mice was monitored throughout the study. In the filter-containing rack, PCR testing of exhaust plenums yielded negative results for all pathogens at all time points of the study. In the rack with open air flow, pathogens detected by PCR analysis of exhaust debris included MHV, Helicobacter spp., P. pneumotropica, pinworms, enteric protozoa, and fur mites; these pathogens were detected in racks housing either 1 or 5 cages of infected mice. Neither MPV nor MNV was detected in exhaust debris, even though prolonged viral shedding was confirmed. These results demonstrate that testing rack exhaust debris from racks with unfiltered air flow detected MHV, enteric bacteria and parasites, and fur mites. However, this method failed to reliably detect MNV or MPV infection of colony animals. PMID:27931317

  6. Characterization of marine debris in North Carolina salt marshes.

    PubMed

    Viehman, Shay; Vander Pluym, Jenny L; Schellinger, Jennifer

    2011-12-01

    Marine debris composition, density, abundance, and accumulation were evaluated in salt marshes in Carteret County, North Carolina seasonally between 2007 and 2009. We assessed relationships between human use patterns and debris type. Wave effects on marine debris density were examined using a GIS-based forecasting tool. We assessed the influence of site wave exposure, period, and height on debris quantity. Presence and abundance of debris were related to wave exposure, vegetation type and proximity of the strata to human population and human use patterns. Plastic pieces accounted for the majority of all debris. Small debris (0-5 cm) was primarily composed of foam pieces and was frequently affiliated with natural wrack. Large debris (>100 cm) was encountered in all marsh habitat types surveyed and was primarily composed of anthropogenic wood and derelict fishing gear. Marsh cleanup efforts should be targeted to specific habitat types or debris types to minimize further damage to sensitive habitats. Published by Elsevier Ltd.

  7. Orbital Debris: Quarterly News, Volume 14, Issue 2

    NASA Technical Reports Server (NTRS)

    Liou, J. C. (Editor); Shoots, Debi (Editor)

    2010-01-01

    This bulletin contains articles from the Orbital Debris Program office. This issue's articles are: "Orbital Debris Success Story --A Decade in the Making", "Old and New Satellite Breakups Identified," "Update on Three Major Debris Clouds," and "MMOD Inspection of the HST Bay 5 Multi-Layer Insulation Panel" about micrometeoroid and orbital debris (MMOD) inspection of the Hubble Space Telescope (HST) insulation panel. A project review is also included (i.e., "Small Debris Observations from the Iridium 33/Cosmos 2251 Collision.") There are also abstra cts of conference papers from the staff of the program office.

  8. The Effect of Debris-Flow Composition on Runout Distance

    NASA Astrophysics Data System (ADS)

    Haas, T. D.; Braat, L.; Leuven, J.; Lokhorst, I.; Kleinhans, M. G.

    2014-12-01

    Estimating runout distance is of major importance for the assessment and mitigation of debris-flow hazards. Debris-flow runout distance depends on debris-flow composition and topography, but state-of-the-art runout prediction methods are mainly based on topographical parameters and debris-flow volume, while composition is generally neglected or incorporated in empirical constants. Here we experimentally investigated the effect of debris-flow composition and topography on runout distance. We created the first small-scale experimental debris flows with self-formed levees, distinct lobes and morphology and texture accurately resembling natural debris flows. In general, debris-flow composition had a larger effect on runout distance than topography. Enhancing channel slope and width, outflow plain slope, debris-flow size and water fraction leads to an increase in runout distance. However, runout distance shows an optimum relation with coarse-material and clay fraction. An increase in coarse-material fraction leads to larger runout distances by increased grain collisional forces and more effective levee formation, but too much coarse debris causes a large accumulation of coarse debris at the flow front, enhancing friction and decreasing runout. An increase in clay fraction initially enlarges the volume and viscosity of the interstitial fluid, liquefying the flow and enhancing runout, while a further increase leads to very viscous flows with high yield strength, reducing runout. These results highlight the importance and further need of research on the relation between debris-flow composition and runout distance. Our experiments further provide valuable insight on the effects of debris-flow composition on depositional mechanisms and deposit morphology.

  9. The effect of debris-flow composition on runout distance

    NASA Astrophysics Data System (ADS)

    de Haas, Tjalling; Braat, Lisanne; Leuven, Jasper; Lokhorst, Ivar; Kleinhans, Maarten

    2015-04-01

    Estimating runout distance is of major importance for the assessment and mitigation of debris-flow hazards. Debris-flow runout distance depends on debris-flow composition and topography, but state-of-the-art runout prediction methods are mainly based on topographical parameters and debris-flow volume, while composition is generally neglected or incorporated in empirical constants. Here we experimentally investigated the effect of debris-flow composition and topography on runout distance. We created the first small-scale experimental debris flows with self-formed levees, distinct lobes and morphology and texture accurately resembling natural debris flows. In general, the effect of debris-flow composition on runout distance was larger than the effect of topography. Enhancing channel slope and width, outflow plain slope, debris-flow size and water fraction leads to an increase in runout distance. However, runout distance shows an optimum relation with coarse-material and clay fraction. An increase in coarse-material fraction leads to larger runout distances by increased grain collisional forces and more effective levee formation, but too much coarse debris causes a large accumulation of coarse debris at the flow front, enhancing friction and decreasing runout. An increase in clay fraction initially enlarges the volume and viscosity of the interstitial fluid, liquefying the flow and enhancing runout, while a further increase leads to very viscous flows with high yield strength, reducing runout. These results highlight the importance and further need of research on the relation between debris-flow composition and runout distance. Our experiments further provide valuable insight on the effects of debris-flow composition on depositional mechanisms and deposit morphology.

  10. Best Mitigation Paths To Effectively Reduce Earth's Orbital Debris

    NASA Technical Reports Server (NTRS)

    Wiegman, Bruce M.

    2009-01-01

    This slide presentation reviews some ways to reduce the problem posed by debris in orbit around the Earth. It reviews the orbital debris environment, the near-term needs to minimize the Kessler syndrome, also known as collisional cascading, a survey of active orbital debris mitigation strategies, the best paths to actively remove orbital debris, and technologies that are required for active debris mitigation.

  11. An adaptive strategy for active debris removal

    NASA Astrophysics Data System (ADS)

    White, Adam E.; Lewis, Hugh G.

    2014-04-01

    Many parameters influence the evolution of the near-Earth debris population, including launch, solar, explosion and mitigation activities, as well as other future uncertainties such as advances in space technology or changes in social and economic drivers that effect the utilisation of space activities. These factors lead to uncertainty in the long-term debris population. This uncertainty makes it difficult to identify potential remediation strategies, involving active debris removal (ADR), that will perform effectively in all possible future cases. Strategies that cannot perform effectively, because of this uncertainty, risk either not achieving their intended purpose, or becoming a hindrance to the efforts of spacecraft manufactures and operators to address the challenges posed by space debris. One method to tackle this uncertainty is to create a strategy that can adapt and respond to the space debris population. This work explores the concept of an adaptive strategy, in terms of the number of objects required to be removed by ADR, to prevent the low Earth orbit (LEO) debris population from growing in size. This was demonstrated by utilising the University of Southampton’s Debris Analysis and Monitoring Architecture to the Geosynchronous Environment (DAMAGE) tool to investigate ADR rates (number of removals per year) that change over time in response to the current space environment, with the requirement of achieving zero growth of the LEO population. DAMAGE was used to generate multiple Monte Carlo projections of the future LEO debris environment. Within each future projection, the debris removal rate was derived at five-year intervals, by a new statistical debris evolutionary model called the Computational Adaptive Strategy to Control Accurately the Debris Environment (CASCADE) model. CASCADE predicted the long-term evolution of the current DAMAGE population with a variety of different ADR rates in order to identify a removal rate that produced a zero net

  12. Evaluating the impacts of marine debris on cetaceans.

    PubMed

    Baulch, Sarah; Perry, Clare

    2014-03-15

    Global in its distribution and pervading all levels of the water column, marine debris poses a serious threat to marine habitats and wildlife. For cetaceans, ingestion or entanglement in debris can cause chronic and acute injuries and increase pollutant loads, resulting in morbidity and mortality. However, knowledge of the severity of effects lags behind that for other species groups. This literature review examines the impacts of marine debris on cetaceans reported to date. It finds that ingestion of debris has been documented in 48 (56% of) cetacean species, with rates of ingestion as high as 31% in some populations. Debris-induced mortality rates of 0-22% of stranded animals were documented, suggesting that debris could be a significant conservation threat to some populations. We identify key data that need to be collected and published to improve understanding of the threat that marine debris poses to cetaceans. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Marine debris in five national parks in Alaska.

    PubMed

    Polasek, L; Bering, J; Kim, H; Neitlich, P; Pister, B; Terwilliger, M; Nicolato, K; Turner, C; Jones, T

    2017-04-15

    Marine debris is a management issue with ecological and recreational impacts for agencies, especially on remote beaches not accessible by road. This project was implemented to remove and document marine debris from five coastal National Park Service units in Alaska. Approximately 80km of coastline were cleaned with over 10,000kg of debris collected. Marine debris was found at all 28 beaches surveyed. Hard plastics were found on every beach and foam was found at every beach except one. Rope/netting was the next most commonly found category, present at 23 beaches. Overall, plastic contributed to 60% of the total weight of debris. Rope/netting (14.6%) was a greater proportion of the weight from all beaches than foam (13.3%). Non-ferrous metal contributed the smallest amount of debris by weight (1.7%). The work forms a reference condition dataset of debris surveyed in the Western Arctic and the Gulf of Alaska within one season. Copyright © 2017. Published by Elsevier Ltd.

  14. Large Area Solid Radiochemistry (LASR) collector at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Waltz, Cory; Gharibyan, Narek; Hardy, Mike; Shaughnessy, Dawn; Jedlovec, Don; Smith, Cal

    2017-08-01

    The flux of neutrons and charged particles produced from inertial confinement fusion experiments at the National Ignition Facility (NIF) induces measurable concentrations of nuclear reaction products in various target materials. The collection and radiochemical analysis of the post-shot debris can be utilized as an implosion diagnostic to obtain information regarding fuel areal density and ablator-fuel mixing. Furthermore, assessment of the debris from specially designed targets, material doped in capsules or mounted on the external surface of the target assembly, can support experiments relevant to nuclear forensic research. To collect the shot debris, we have deployed the Large Area Solid Radiochemistry Collector (LASR) at NIF. LASR uses a main collector plate that contains a large collection foil with an exposed 20 cm diameter surface located ˜50 cm from the NIF target. This covers ˜0.12 steradians, or about 1% of the total solid angle. We will describe the design, analysis, and operation of this experimental platform as well as the initial results. To speed up the design process 3-dimensional printing was utilized. Design analysis includes the dynamic loading of the NIF target vaporized mass, which was modeled using LS-DYNA.

  15. Analyzing costs of space debris mitigation methods

    NASA Astrophysics Data System (ADS)

    Wiedemann, C.; Krag, H.; Bendisch, J.; Sdunnus, H.

    2004-01-01

    The steadily increasing number of space objects poses a considerable hazard to all kinds of spacecraft. To reduce the risks to future space missions different debris mitigation measures and spacecraft protection techniques have been investigated during the last years. However, the economic efficiency has not been considered yet in this context. Current studies have the objective to evaluate the mission costs due to space debris in a business as usual (no mitigation) scenario compared to the missions costs considering debris mitigation. The aim is an estimation of the time until the investment in debris mitigation will lead to an effective reduction of mission costs. This paper presents the results of investigations on the key issues of cost estimation for spacecraft and the influence of debris mitigation and shielding on cost. Mitigation strategies like the reduction of orbital lifetime and de- or re-orbit of non-operational satellites are methods to control the space debris environment. These methods result in an increase of costs. In a first step the overall costs of different types of unmanned satellites are analyzed. A selected cost model is simplified and generalized for an application on all operational satellites. In a next step the influence of space debris on cost is treated, if the implementation of mitigation strategies is considered.

  16. Spacelab J air filter debris analysis

    NASA Technical Reports Server (NTRS)

    Obenhuber, Donald C.

    1993-01-01

    Filter debris from the Spacelab module SLJ of STS-49 was analyzed for microbial contamination. Debris for cabin and avionics filters was collected by Kennedy Space Center personnel on 1 Oct. 1992, approximately 5 days postflight. The concentration of microorganisms found was similar to previous Spacelab missions averaging 7.4E+4 CFU/mL for avionics filter debris and 4.5E+6 CFU/mL for the cabin filter debris. A similar diversity of bacterial types was found in the two filters. Of the 13 different bacterial types identified from the cabin and avionics samples, 6 were common to both filters. The overall analysis of these samples as compared to those of previous missions shows no significant differences.

  17. Uncovering glacier dynamics beneath a debris mantle

    NASA Astrophysics Data System (ADS)

    Lefeuvre, P.-M.; Ng, F. S. L.

    2012-04-01

    Debris-covered glaciers (DCGs) have an extensive sediment mantle whose low albedo influences their surface energy balance to cause a buffering effect that could enhance or reduce ablation rates depending on the sediment thickness. The last effect suggests that some DCGs may be less sensitive to climate change and survive for longer than debris-free (or 'clean') glaciers under sustained climatic warming. However, the origin of DCGs is debated and the precise impact of the debris mantle on their flow dynamics and surface geometry has not been quantified. Here we investigate these issues with a numerical model that encapsulates ice-flow physics and surface debris evolution and transport along a glacier flow-line, as well as couples these with glacier mass balance. We model the impact of surface debris on ablation rates by a mathematical function based on published empirical data (including Ostrem's curve). A key interest is potential positive feedback of ablation on debris thickening and lowering of surface albedo. Model simulations show that when DCGs evolve to attain steady-state profiles, they reach lower elevations than clean glaciers do for the same initial and climatic conditions. Their mass-balance profile at steady state displays an inversion near the snout (where the debris cover is thickest) that is not observed in the clean-glacier simulations. In these cases, where the mantle causes complete buffering to inhibit ablation, the DCG does not reach a steady-state profile, and the sediment thickness evolves to a steady value that depends sensitively on the glacier surface velocities. Variation in the assumed englacial debris concentration in our simulations also determines glacier behaviour. With low englacial debris concentration, the DCG retreats initially while its mass-balance gradient steepens, but the glacier re-advances if it subsequently builds up a thick enough debris cover to cause complete buffering. We identify possible ways and challenges of

  18. Polyelectrolyte-coated ion exchangers for cell-resistant expanded bed adsorption.

    PubMed

    Dainiak, Maria B; Galaev, Igor Yu; Mattiasson, Bo

    2002-01-01

    Adsorption chromatography in expanded beds is a widely used technology for direct capture of target proteins from fermentation broths. However, in many cases this method cannot be applied as a result of the strong tendency of cells or cell debris to interact with the adsorbent beads. To prevent contamination of the expanded bed with the biomass, STREAMLINE DEAE, anion exchanger designed for expanded bed adsorption, was modified with a layer of poly(acrylic acid) (PAA). The shielding layer of polyelectrolyte was attached to the surface of the matrix beads via electrostatic interactions. PAA with a high degree of polymerization was chosen to prevent diffusion of large polymer molecules into the pores of adsorbent. Thus, the shielding layer of PAA was adsorbed only at the mouth of the pores of STREAMLINE DEAE beads and only marginally decreased the binding capacity of the ion exchanger for bovine serum albumin, the model protein in this study. PAA-coated STREAMLINE DEAE practically did not interact with yeast cells, which otherwise bound strongly to the native adsorbent at neutral conditions. Cell-resistant PAA-coated anion exchanger was successfully used for isolation of BSA from the model protein mixture containing BSA, lysozyme (positively charged at applied conditions), and yeast cells. The layer of PAA was stable under mild elution conditions, and the modified adsorbent could be used in the repeated purification cycles.

  19. Observations of Human-Made Debris in Earth Orbit

    NASA Technical Reports Server (NTRS)

    Cowardia, Heather

    2011-01-01

    Orbital debris is defined as any human-made object in orbit about the Earth that no longer serves a useful purpose. Beginning in 1957 with the launch of Sputnik 1, there have been more than 4,700 launches, with each launch increasing the potential for impacts from orbital debris. Almost 55 years later there are over 16,000 catalogued objects in orbit over 10 cm in size. Agencies world-wide have realized this is a growing issue for all users of the space environment. To address the orbital debris issue, the Inter-Agency Space Debris Coordination Committee (IADC) was established to collaborate on monitoring, characterizing, and modeling orbital debris, as well as formulating policies and procedures to help control the risk of collisions and population growth. One area of fundamental interest is measurements of the space debris environment. NASA has been utilizing radar and optical measurements to survey the different orbital regimes of space debris for over 25 years, as well as using returned surfaces to aid in determining the flux and size of debris that are too small to detect with ground-based sensors. This paper will concentrate on the optical techniques used by NASA to observe the space debris environment, specifically in the Geosynchronous earth Orbit (GEO) region where radar capability is severely limited.

  20. Understanding sources, sinks, and transport of marine debris

    NASA Astrophysics Data System (ADS)

    Law, Kara Lavender; Maximenko, Nikolai

    2011-07-01

    Fifth International Marine Debris Conference: Hydrodynamics of Marine Debris; Honolulu, Hawaii, 20 March 2011; Ocean pollution in the form of marine debris, especially plastic debris, has received increasing public and media attention in recent years through striking but frequently inaccurate descriptions of “garbage patches.” Marine debris is composed of all manufactured materials, including glass, metal, paper, fibers, and plastic, that have been deliberately dumped or that accidentally entered the marine environment. Marine debris is most visible on beaches, but it has been observed in all oceans and in such remote locations as on the deep seabed and floating in the middle of subtropical ocean gyres. While many initiatives have been developed to solve this pollution problem through prevention and cleanup efforts, there is relatively little scientific information available to assess the current status of the problem or to provide metrics to gauge the success of remediation measures. With this in mind, a full-day workshop entitled “Hydrodynamics of Marine Debris” was convened at the Fifth International Marine Debris Conference in Hawaii, bringing together observational scientists and oceanographic modelers to outline the steps necessary to quantify the major sources and sinks of marine debris and the pathways between them. The ultimate goal in integrating the two approaches of study is to quantify the basinscale and global inventory of marine debris by closing the associated mass budgets.

  1. Biomass drying in a pulsed fluidized bed without inert bed particles

    DOE PAGES

    Jia, Dening; Bi, Xiaotao; Lim, C. Jim; ...

    2016-08-29

    Batch drying was performed in the pulsed fluidized bed with various species of biomass particles as an indicator of gas–solid contact efficiency and mass transfer rate under different operating conditions including pulsation duty cycle and particle size distribution. The fluidization of cohesive biomass particles benefited from the shorter opening time of pulsed gas flow and increased peak pressure drop. The presence of fines enhanced gas–solid contact of large and irregular biomass particles, as well as the mass transfer efficiency. A drying model based on two-phase theory was proposed, from which effective diffusivity was calculated for various gas flow rates, temperaturemore » and pulsation frequency. Intricate relationship was discovered between pulsation frequency and effective diffusivity, as mass transfer was deeply connected with the hydrodynamics. Effective diffusivity was also found to be proportional to gas flow rate and drying temperature. In conclusion, operating near the natural frequency of the system also favored drying and mass transfer.« less

  2. Effects on the orbital debris environment due to solar activity

    NASA Technical Reports Server (NTRS)

    Kessler, Donald J.; Anz-Meador, Phillip D.

    1990-01-01

    The rate that earth-orbiting debris is removed from the environment is dependent on a number of factors which include orbital altitude and solar activity. It is generally believed that at lower altitudes and especially during periods of high solar activity, debris generated in the past will be eliminated from the environment. While some debris is eliminated, most is replaced by old debris from higher altitudes or new debris from recent launches. Some low altitude debris, which would reenter if the debris were in circular orbits, does not reenter because the debris is in higher-energy elliptical orbits.

  3. Zodiac II: Debris Disk Science from a Balloon

    NASA Technical Reports Server (NTRS)

    Bryden, Geoffrey; Traub, Wesley; Roberts, Lewis C., Jr.; Bruno, Robin; Unwin, Stephen; Backovsky, Stan; Brugarolas, Paul; Chakrabarti, Supriya; Chen, Pin; Hillenbrand, Lynne; hide

    2011-01-01

    Zodiac II is a proposed balloon-borne science investigation of debris disks around nearby stars. Debris disks are analogs of the Asteroid Belt (mainly rocky) and Kuiper Belt (mainly icy) in our Solar System. Zodiac II will measure the size, shape, brightness, and color of a statistically significant sample of disks. These measurements will enable us to probe these fundamental questions: what do debris disks tell us about the evolution of planetary systems; how are debris disks produced; how are debris disks shaped by planets; what materials are debris disks made of; how much dust do debris disks make sa they grind down; and how long do debris disks live? In addition, Zodiac II will observe hot, young exoplanets as targets of opportunity. The Zodiac II instrument is a 1.1-m diameter SiC telescope and an imaging coronagraph on a gondola carried by a stratospheric balloon. Its data product is a set of images of each targeted debris disk in four broad visible wavelength bands. Zodiac II will address its science questions by taking high-resolution, multi-wavelength images of the debris disks around tens of nearby stars. Mid-latitude flights are considered: overnight test flights within the United States followed by half-global flights in the Southern Hemisphere. These longer flights are required to fully explore the set of known debris disks accessible only to Zodiac II. On these targets, it will be 100 times more sensitive than the Hubble Space Telescope's Advanced Camera for Surveys (HST/ACS); no existing telescope can match the Zodiac II contrast and resolution performance. A second objective of Zodiac II is to use the near-space environment to raise the Technology Readiness Level (TRL) of SiC mirrors, internal coronagraphs, deformable mirrors, and wavefront sensing and control, all potentially needed for a future space-based telescope for high-contrast exoplanet imaging.

  4. Zodiac II: Debris Disk Science from a Balloon

    NASA Technical Reports Server (NTRS)

    Bryden, Geoffrey; Traub, Wesley; Roberts, Lewis C., Jr.; Bruno, Robin; Unwin, Stephen; Backovsky, Stan; Brugarolas, Paul; Chakrabarti, Supriya; Chen, Pin; Hillenbrand, Lynne; hide

    2011-01-01

    Zodiac II is a proposed balloon-borne science investigation of debris disks around nearby stars. Debris disks are analogs of the Asteroid Belt (mainly rocky) and Kuiper Belt (mainly icy) in our Solar System. Zodiac II will measure the size, shape, brightness, and color of a statistically significant sample of disks. These measurements will enable us to probe these fundamental questions: what do debris disks tell us about the evolution of planetary systems; how are debris disks produced; how are debris disks shaped by planets; what materials are debris disks made of; how much dust do debris disks make as they grind down; and how long do debris disks live? In addition, Zodiac II will observe hot, young exoplanets as targets of opportunity. The Zodiac II instrument is a 1.1-m diameter SiC (Silicone carbide) telescope and an imaging coronagraph on a gondola carried by a stratospheric balloon. Its data product is a set of images of each targeted debris disk in four broad visible-wavelength bands. Zodiac II will address its science questions by taking high-resolution, multi-wavelength images of the debris disks around tens of nearby stars. Mid-latitude flights are considered: overnight test flights in the US followed by half-global flights in the Southern Hemisphere. These longer flights are required to fully explore the set of known debris disks accessible only to Zodiac II. On these targets, it will be 100 times more sensitive than the Hubble Space Telescope's Advanced Camera for Surveys (HST/ACS); no existing telescope can match the Zodiac II contrast and resolution performance. A second objective of Zodiac II is to use the near-space environment to raise the Technology Readiness Level (TRL) of SiC mirrors, internal coronagraphs, deformable mirrors, and wavefront sensing and control, all potentially needed for a future space-based telescope for high-contrast exoplanet imaging.

  5. POST Earthquake Debris Management — AN Overview

    NASA Astrophysics Data System (ADS)

    Sarkar, Raju

    Every year natural disasters, such as fires, floods, earthquakes, hurricanes, landslides, tsunami, and tornadoes, challenge various communities of the world. Earthquakes strike with varying degrees of severity and pose both short- and long-term challenges to public service providers. Earthquakes generate shock waves and displace the ground along fault lines. These seismic forces can bring down buildings and bridges in a localized area and damage buildings and other structures in a far wider area. Secondary damage from fires, explosions, and localized flooding from broken water pipes can increase the amount of debris. Earthquake debris includes building materials, personal property, and sediment from landslides. The management of this debris, as well as the waste generated during the reconstruction works, can place significant challenges on the national and local capacities. Debris removal is a major component of every post earthquake recovery operation. Much of the debris generated from earthquake is not hazardous. Soil, building material, and green waste, such as trees and shrubs, make up most of the volume of earthquake debris. These wastes not only create significant health problems and a very unpleasant living environment if not disposed of safely and appropriately, but also can subsequently impose economical burdens on the reconstruction phase. In practice, most of the debris may be either disposed of at landfill sites, reused as materials for construction or recycled into useful commodities Therefore, the debris clearance operation should focus on the geotechnical engineering approach as an important post earthquake issue to control the quality of the incoming flow of potential soil materials. In this paper, the importance of an emergency management perspective in this geotechnical approach that takes into account the different criteria related to the operation execution is proposed by highlighting the key issues concerning the handling of the construction

  6. Marine Debris Composition on Remote Alaskan National Park Shores

    NASA Astrophysics Data System (ADS)

    Pister, B.; Kunisch, E.; Polasek, L.; Bering, J.; Kim, S.; Neitlich, P.; Nicolato, K.

    2016-02-01

    Marine debris is a pervasive problem along coastlines around the world. The National Park Service manages approximately 3500 miles of shoreline in Alaska's national park units combined. Most of these shores are remote, difficult and expensive to access. In 2011 the Tohoku earthquake hit Japan and generated a devastating tsunami that washed an estimated 150 million tons of debris out to sea. Much of the debris washed ashore in Alaska. The tsunami brought new attention to the long standing problem of marine debris. In 2015 the National Park Service mounted a two pronged effort to remove as much debris as possible from the shores of five park units in Alaska, and initiate education programs about the issue. Almost 11,000 kg of debris were removed from the shores of: Wrangell-St. Elias National Park, Kenai Fjords National Park, Katmai National Park, Bering Land Bridge National Preserve and Cape Krusenstern National Monument. Approximately 58% of the debris was plastic. Although much of the debris resembled items expected as a result of the tsunami, a great percentage of the debris was clearly from other sources, such as fishing and shipping. Preliminary analysis suggests that debris composition varied significantly between parks, possibly from locally-derived sources. This can influence how the National Park Service creates educational outreach programs that focus on marine debris prevention exercises.

  7. Validating the MFiX-DEM Model for Flow Regime Prediction in a 3D Spouted Bed

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Banerjee, Subhodeep; Guenther, Chris; Rogers, William A.

    The spout-fluidized bed reactor with relatively large oxygen carrier particles offers several advantages in chemical looping combustion operation using solid fuels. The large difference in size and weight between the oxygen carrier particles and the smaller coal or ash particles allows the oxygen carrier to be easily segregated for recirculation; the increased solids mixing due to dynamic flow pattern in the spout-fluidization regime prevents agglomeration. The primary objective in this work is to determine the effectiveness of the MFiX-DEM model in predicting the flow regime in a spouted bed. Successful validation of the code will allow the user to finemore » tune the operating conditions of a spouted bed to achieve the desired operating condition.« less

  8. Gear Damage Detection Using Oil Debris Analysis

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.

    2001-01-01

    The purpose of this paper was to verify, when using an oil debris sensor, that accumulated mass predicts gear pitting damage and to identify a method to set threshold limits for damaged gears. Oil debris data was collected from 8 experiments with no damage and 8 with pitting damage in the NASA Glenn Spur Gear Fatigue Rig. Oil debris feature analysis was performed on this data. Video images of damage progression were also collected from 6 of the experiments with pitting damage. During each test, data from an oil debris sensor was monitored and recorded for the occurrence of pitting damage. The data measured from the oil debris sensor during experiments with damage and with no damage was used to identify membership functions to build a simple fuzzy logic model. Using fuzzy logic techniques and the oil debris data, threshold limits were defined that discriminate between stages of pitting wear. Results indicate accumulated mass combined with fuzzy logic analysis techniques is a good predictor of pitting damage on spur gears.

  9. Meteoroid/Debris Shielding

    NASA Technical Reports Server (NTRS)

    Christiansen, Eric L.

    2003-01-01

    This report provides innovative, low-weight shielding solutions for spacecraft and the ballistic limit equations that define the shield's performance in the meteoroid/debris environment. Analyses and hypervelocity impact testing results are described that have been used in developing the shields and equations. Spacecraft shielding design and operational practices described in this report are used to provide effective spacecraft protection from meteoroid and debris impacts. Specific shield applications for the International Space Station (ISS), Space Shuttle Orbiter and the CONTOUR (Comet Nucleus Tour) space probe are provided. Whipple, Multi-Shock and Stuffed Whipple shield applications are described.

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

    NASA Technical Reports Server (NTRS)

    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

  11. DebriSat Laboratory Analyses

    DTIC Science & Technology

    2015-01-05

    droplets. Fluorine from Teflon wire insulation was also common in the SEM stub and witness plates deposits. Nano droplets of metallic materials...and Debris-LV debris. Aluminum was from the Al honeycomb, nadir and zenith panels, structural core and COPV liner. Aluminum oxide particles were...three pieces: Outer Nylon shell (sabot) with 2 part hollow aluminum insert. • ~600 grams, 8.6 cm diameter X 10.3 cm long – size of a soup can

  12. Searching for Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Lederer, Susan M.; Abercromby, Kira J.; Barker, Edwin S.; Burkhardt, Andrew; Cowardin, Heather; Krisko, Paula; Silha, Jiri

    2012-01-01

    We report on results from a search for optically faint debris (defined as R > 20th magnitude, or smaller than 10 cm assuming an albedo of 0.175)) at geosynchronous orbit (GEO) using the 6.5-m Magellan telescope "Walter Baade" at Las Campanas Observatory in Chile. Our goal is to characterize the brightness distribution of debris to the faintest limiting magnitude possible. Our data was obtained during 6 hours of observing time during the photometric nights of 26 and 27 March 2011 with the IMACS f/2 instrument, which has a field of view (fov) of 0.5 degrees in diameter. All observations were obtained through a Sloan r filter, and calibrated by observations of Landolt standard stars. Our primary objective was to search for optically faint objects from one of the few known fragmentations at GEO: the Titan 3C Transtage (1968-081) fragmentation in 1992. Eight debris pieces and the parent rocket body are in the Space Surveillance Network public catalog. We successfully tracked two cataloged pieces of Titan debris with the 6.5-m telescope, followed by a survey for unknown objects on similar orbits but with different mean anomalies. To establish the bright end of the debris population, calibrated observations were acquired on the same field centers, telescope rates, and time period with a similar filter on the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American Observatory, Chile. We will show the calibrated brightness distributions from both telescopes, and compare the observed brightness distributions with that predicted for various population models of debris of different sizes.

  13. Reduction of CO2 and orbital debris: can CO2 emission trading principles be applied to debris reduction?

    NASA Astrophysics Data System (ADS)

    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

  14. Quantitative Assessment of Apical Debris Extrusion and Intracanal Debris in the Apical Third, Using Hand Instrumentation and Three Rotary Instrumentation Systems

    PubMed Central

    H.K., Sowmya; T.S., Subhash; Goel, Beena Rani; T.N., Nandini; Bhandi, Shilpa H.

    2014-01-01

    Introduction: Decreased apical extrusion of debris and apical one third debris have strong implications for decreased incidence of postoperative inflammation and pain. Thus, the aim of this study was to assess quantitatively the apical extrusion of debris and intracanal debris in the apical third during root canal instrumentation using hand and three different types of rotary instruments. Methodology: Sixty freshly extracted single rooted human teeth were randomly divided into four groups. Canal preparation was done using step-back with hand instrumentation, crown-down technique with respect to ProTaper and K3, and hybrid technique with LightSpeed LSX. Irrigation was done with NaOCl, EDTA, and normal saline and for final irrigation, EndoVac system was used. The apically extruded debris was collected on the pre-weighed Millipore plastic filter disk and weighed using microbalance. The teeth were submitted to the histological processing. Sections from the apical third were analyzed by a trinocular research microscope that was coupled to a computer where the images were captured and analyzed using image proplus V4.1.0.0 software. The mean weight of extruded debris for each group and intracanal debris in the root canal was statistically analyzed by a Kruskal-Wallis one-way analysis of variance and Mann-Whitney U test. Results: The result showed that, hand instrumentation using K files showed the highest amount of debris extrusion apically when compared to ProTaper, K3 and LightSpeed LSX. The result also showed that there was no statistically significant difference between the groups in relation to presence of intracanal debris in the apical one third. Conclusion: Based on the results, all instrumentation techniques produced debris extrusion. The engine driven Ni-Ti systems extruded significantly less apical debris than hand instrumentation. There was no statistically significant difference between the groups in relation to presence of intracanal debris in the apical one

  15. An analysis of the orbital distribution of solid rocket motor slag

    NASA Astrophysics Data System (ADS)

    Horstman, Matthew F.; Mulrooney, Mark

    2009-01-01

    The contribution by solid rocket motors (SRMs) to the orbital debris environment is potentially significant and insufficiently studied. Design and combustion processes can lead to the emission of enough by-products to warrant assessment of their contribution to orbital debris. These particles are formed during SRM tail-off, or burn termination, by the rapid solidification of molten Al2O3 slag accumulated during the burn. The propensity of SRMs to generate particles larger than 100μm raises concerns regarding the debris environment. Sizes as large as 1 cm have been witnessed in ground tests, and comparable sizes have been estimated via observations of sub-orbital tail-off events. Utilizing previous research we have developed more sophisticated size distributions and modeled the time evolution of resultant orbital populations using a historical database of SRM launches, propellant, and likely location and time of tail-off. This analysis indicates that SRM ejecta is a significant component of the debris environment.

  16. A New Dry Flue Gas Desulfurization Process-Underfeed Circulating Spouted Bed

    NASA Astrophysics Data System (ADS)

    Tao, M.; Jin, B. S.; Yang, Y. P.

    Applying an underfeed system, the underfeed circulating spouted bed was designed as a desulfurization reactor. The main objective of the technology is to improve the mixing effect and distribution uniformity of solid particles, and therefore to advance the desulfurization efficiency and calcium utility. In this article, a series of experimental studies were conducted to investigate the fluidization behavior of the solid-gas two-phase flow in the riser. The results show that the technology can distinctly improve the distribution of gas velocity and particle flux on sections compared with the facefeed style. Analysis of pressure fluctuation signals indicates that the operation parameters have significant influence on the flow field in the reaction bed. The existence of injecting flow near the underfeed nozzle has an evident effect on strengthening the particle mixing.

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

    NASA Astrophysics Data System (ADS)

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

    2017-12-01

    floating debris and bed load movement, large intake screens to reduce velocity, and a log-boom debris deflection system that floats with the river level. This project demonstrated a time and cost efficient approach to develop reliable solutions and hydrodynamic data describing design alternatives performance.

  18. Solid propellant exhausted aluminum oxide and hydrogen chloride - Environmental considerations

    NASA Technical Reports Server (NTRS)

    Cofer, W. R., III; Winstead, E. L.; Purgold, G. C.; Edahl, R. A.

    1993-01-01

    Measurements of gaseous hydrogen chloride (HCl) and particulate aluminum oxide (Al2O3) were made during penetrations of five Space Shuttle exhaust clouds and one static ground test firing of a shuttle booster. Instrumented aircraft were used to penetrate exhaust clouds and to measure and/or collect samples of exhaust for subsequent analyses. The focus was on the primary solid rocket motor exhaust products, HCl and Al2O3, from the Space Shuttle's solid boosters. Time-dependent behavior of HCl was determined for the exhaust clouds. Composition, morphology, surface chemistry, and particle size distributions were determined for the exhausted Al2O3. Results determined for the exhaust cloud from the static test firing were complicated by having large amounts of entrained alkaline ground debris (soil) in the lofted cloud. The entrained debris may have contributed to neutralization of in-cloud HCl.

  19. Development of the Space Debris Sensor (SDS)

    NASA Technical Reports Server (NTRS)

    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.

  20. Aquatic Debris Detection Using Embedded Camera Sensors

    PubMed Central

    Wang, Yong; Wang, Dianhong; Lu, Qian; Luo, Dapeng; Fang, Wu

    2015-01-01

    Aquatic debris monitoring is of great importance to human health, aquatic habitats and water transport. In this paper, we first introduce the prototype of an aquatic sensor node equipped with an embedded camera sensor. Based on this sensing platform, we propose a fast and accurate debris detection algorithm. Our method is specifically designed based on compressive sensing theory to give full consideration to the unique challenges in aquatic environments, such as waves, swaying reflections, and tight energy budget. To upload debris images, we use an efficient sparse recovery algorithm in which only a few linear measurements need to be transmitted for image reconstruction. Besides, we implement the host software and test the debris detection algorithm on realistically deployed aquatic sensor nodes. The experimental results demonstrate that our approach is reliable and feasible for debris detection using camera sensors in aquatic environments. PMID:25647741

  1. Solid fuel combustion system for gas turbine engine

    DOEpatents

    Wilkes, Colin; Mongia, Hukam C.

    1993-01-01

    A solid fuel, pressurized fluidized bed combustion system for a gas turbine engine includes a carbonizer outside of the engine for gasifying coal to a low Btu fuel gas in a first fraction of compressor discharge, a pressurized fluidized bed outside of the engine for combusting the char residue from the carbonizer in a second fraction of compressor discharge to produce low temperature vitiated air, and a fuel-rich, fuel-lean staged topping combustor inside the engine in a compressed air plenum thereof. Diversion of less than 100% of compressor discharge outside the engine minimizes the expense of fabricating and maintaining conduits for transferring high pressure and high temperature gas and incorporation of the topping combustor in the compressed air plenum of the engine minimizes the expense of modifying otherwise conventional gas turbine engines for solid fuel, pressurized fluidized bed combustion.

  2. Linking effects of anthropogenic debris to ecological impacts

    PubMed Central

    Browne, Mark Anthony; Underwood, A. J.; Chapman, M. G.; Williams, Rob; Thompson, Richard C.; van Franeker, Jan A.

    2015-01-01

    Accelerated contamination of habitats with debris has caused increased effort to determine ecological impacts. Strikingly, most work on organisms focuses on sublethal responses to plastic debris. This is controversial because (i) researchers have ignored medical insights about the mechanisms that link effects of debris across lower levels of biological organization to disease and mortality, and (ii) debris is considered non-hazardous by policy-makers, possibly because individuals can be injured or removed from populations and assemblages without ecological impacts. We reviewed the mechanisms that link effects of debris across lower levels of biological organization to assemblages and populations. Using plastic, we show microplastics reduce the ‘health’, feeding, growth and survival of ecosystem engineers. Larger debris alters assemblages because fishing-gear and tyres kill animals and damage habitat-forming plants, and because floating bottles facilitate recruitment and survival of novel taxa. Where ecological linkages are not known, we show how to establish hypothetical links by synthesizing studies to assess the likelihood of impacts. We also consider how population models examine ecological linkages and guide management of ecological impacts. We show that by focusing on linkages to ecological impacts rather than the presence of debris and its sublethal impacts, we could reduce threats posed by debris. PMID:25904661

  3. Orbital debris and near-Earth environmental management: A chronology

    NASA Technical Reports Server (NTRS)

    Portree, David S. F.; Loftus, Joseph P., Jr.

    1993-01-01

    This chronology covers the 32-year history of orbital debris and near-Earth environmental concerns. It tracks near-Earth environmental hazard creation, research, observation, experimentation, management, mitigation, protection, and policy-making, with emphasis on the orbital debris problem. Included are the Project West Ford experiments; Soviet ASAT tests and U.S. Delta upper stage explosions; the Ariane V16 explosion, U.N. treaties pertinent to near-Earth environmental problems, the PARCS tests; space nuclear power issues, the SPS/orbital debris link; Space Shuttle and space station orbital debris issues; the Solwind ASAT test; milestones in theory and modeling the Cosmos 954, Salyut 7, and Skylab reentries; the orbital debris/meteoroid research link; detection system development; orbital debris shielding development; popular culture and orbital debris; Solar Max results; LDEF results; orbital debris issues peculiar to geosynchronous orbit, including reboost policies and the stable plane; seminal papers, reports, and studies; the increasing effects of space activities on astronomy; and growing international awareness of the near-Earth environment.

  4. An Overview of NASA's Oribital Debris Environment Model

    NASA Technical Reports Server (NTRS)

    Matney, Mark

    2010-01-01

    Using updated measurement data, analysis tools, and modeling techniques; the NASA Orbital Debris Program Office has created a new Orbital Debris Environment Model. This model extends the coverage of orbital debris flux throughout the Earth orbit environment, and includes information on the mass density of the debris as well as the uncertainties in the model environment. This paper will give an overview of this model and its implications for spacecraft risk analysis.

  5. Debris Flow Risk mitigation by the means of flexible barriers. Experimental and field tests.

    NASA Astrophysics Data System (ADS)

    Canelli, L.; Ferrero, A. M.; Segalini, A.

    2012-04-01

    Debris flow risk mitigation using net barriers is an option that was not considered until few years ago, probably because of the lack of scientific evidences about their efficiency and solid guidelines for their design and construction. On site evidences (Segalini et al, 2008) showed that a rock fall deformable barrier can efficiently intercept the whole volume or just a portion of the mobilized debris without losing its stability and efficiency, actually performing a different task form that it was originally designed for. Although the final purpose of both types of barriers (rock fall and debris) is to reduce the impact energy of the moving mass by dissipating impact energy through the deformation of the net and of the dissipating elements, it is noteworthy that the physics of the impact is extremely different between the two phenomena. The rock fall barrier needs to dissipate the energy of a single block generally concentrated on the center of the net panel (design conditions). The debris flow barrier, generally installed inside a debris channel, should be able to dissipate the impact energy that the debris induces across the whole section of the channel. Moreover, the recurring characteristic of the debris flows will cause multiple impact on the barrier and therefore, the structure should be able to absorb a significant amount of energy even if partially filled and considerably deformed. In order to introduce useful guidelines for the design and production of debris flow net barriers, this paper describes: 1. Part of the results obtained from the laboratory experiment carried out in a scaled channel and aimed to estimate the most realistic thrust vs time relationship induced by a debris flow on a deformable and rigid structure; these results were partially presented last year at the EGU 2011; 2. A large scale field test carried out in a quarry located in Tambre d'Alpago (Belluno Province) on the Eastern Italian Dolomites for the analysis of the behavior of a

  6. The 1999 UNCOPUOS "Technical report on space debris" and the new work plan on space debris (2002 - 2005): perspectives and legal consequences

    NASA Astrophysics Data System (ADS)

    Benkö, Marietta; Schrogl, Kai-Uwe

    2001-10-01

    In February 1999, the Scientific and Technical Subcommittee (STSC) of the UN Committee on the Peaceful Uses of Outer Space (UNCOPUOS) adopted a "Technical Report on Space Debris". This was the result of intensive negotiations during a multi-year workplan on space debris, which had been the centerpiece of the technical work of the STSC during these years. The Report is the first document on space debris, presenting the status of space debris research and the problems resulting from space debris. It has the status of an analysis accepted by all governments. Following its adoption, the Report was presented to UNISPACE III and provided the basis for discussions in this Inter-governmental Conference as well as in the Technical Forum, which - at the same time - dealt with the technical as well as the legal aspects of the exploration and use of outer space. The adoption of the Conference Report finalized the workplan in the STSC, but the subject of space debris still remains on the agenda, where until now every year a special aspect is discussed in detail. The Report does not suggest the establishment of an agenda item "space debris" in the UNCOPUOS Legal Subcommittee (LSC). It is very reluctant in even mentioning legal aspects of the space debris issue. The strict and full concentration on technical aspects was a precondition made by a number of Member States for their constructive participation in the elaboration to establish an agenda item on space debris there, were completely detached from that process. Those, who had expected that the adoption of the Report would inevitably lead to formal negotiations in the LSC were deceived so far. Nevertheless, the Report provides a number of starting points for drafting regulation concerning the prevention of space debris as well as debris mitigation measures which also built on work already done by the Inter-Agency Space Debris Coordination Committee (IADC) and its member agencies. This paper describes the status of the

  7. Apparatus and method for determining solids circulation rate

    DOEpatents

    Ludlow, J Christopher [Morgantown, WV; Spenik, James L [Morgantown, WV

    2012-02-14

    The invention relates to a method of determining bed velocity and solids circulation rate in a standpipe experiencing a moving packed bed flow, such as the in the standpipe section of a circulating bed fluidized reactor The method utilizes in-situ measurement of differential pressure over known axial lengths of the standpipe in conjunction with in-situ gas velocity measurement for a novel application of Ergun equations allowing determination of standpipe void fraction and moving packed bed velocity. The method takes advantage of the moving packed bed property of constant void fraction in order to integrate measured parameters into simultaneous solution of Ergun-based equations and conservation of mass equations across multiple sections of the standpipe.

  8. Summary of Orbital Debris Workshop

    NASA Technical Reports Server (NTRS)

    Kessler, D. J.

    1982-01-01

    An Orbital Debris Workshop was conducted in July 1982. The working groups established were related to measurements of large particles, modeling of large particles, measurements of small particles, spacecraft hazard and shielding requirements, and space object management. The results of the Orbital Debris Workshop reaffirm the need for research to better understand the character of orbital debris, its effects on future spacecraft, and the related requirements for policy. A clear charter is required for this research to receive the necessary support, focus, and coordination. It was recommended that NASA assume the role of lead agency. The first task is to develop an overall plan with both Department of Defense and the North American Aerospace Defense Command participation.

  9. Formation of lobate debris aprons on Mars: Assessment of regional ice sheet collapse and debris-cover armoring

    NASA Astrophysics Data System (ADS)

    Fastook, James L.; Head, James W.; Marchant, David R.

    2014-01-01

    Lobate debris aprons (LDA) are lobate-shaped aprons surrounding scarps and isolated massifs that are concentrated in the vicinity of the northern Dichotomy Boundary on Mars. LDAs have been interpreted as (1) ice-cemented talus aprons undergoing viscous flow, (2) local debris-covered alpine-like glaciers, or (3) remnants of the collapse of a regional retreating ice sheet. We investigate the plausibility that LDAs are remnants of a more extensive regional ice sheet by modeling this process. We find that as a regional ice sheet collapses, the surface drops below cliff and massif bedrock margins, exposing bedrock and regolith, and initiating debris deposition on the surface of a cold-based glacier. Reduced sublimation due to debris-cover armoring of the proto-LDA surface produces a surface slope and consequent ice flow that carries the armoring debris away from the rock outcrops. As collapse and ice retreat continue the debris train eventually reaches the substrate surface at the front of the glacier, leaving the entire LDA armored by debris cover. Using a simplified ice flow model we are able to characterize the temperature and sublimation rate that would be necessary to produce LDAs with a wide range of specified lateral extents and thicknesses. We then apply this method to a database of documented LDA parameters (height, lateral extent) from the Dichotomy Boundary region, and assess the implications for predicted climate conditions during their formation and the range of formation times implied by the model. We find that for the population examined here, typical temperatures are in the range of -85 to -40 °C and typical sublimation rates lie in the range of 6-14 mm/a. Lobate debris apron formation times (from the point of bedrock exposure to complete debris cover) cluster near 400-500 ka. These results show that LDA length and thickness characteristics are consistent with climate conditions and a formation scenario typical of the collapse of a regional retreating

  10. A fluidized bed desorption system for recycling mercury from contaminated soil

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Harriss, C.; Baum, D.L. Jr.; Read, W.L.

    1995-12-31

    The land disposal restrictions effective for wastes containing mercury have created a need for technologies that can meet the best demonstrated available technologies (BDAT) treatment standards. In the past, technologies for mercury were in short supply. In addition to the already existing short supply, the natural gas industry has begun to remediate the numerous metering sites that have been contaminated with mercury from manometers installed along their pipelines. To meet the need for a mercury technology, Philip Environmental Services Corporation (Philip) evaluated and tested two different technologies capable of recovering mercury from contaminated soil. Philip initially performed some tests usingmore » gravitational methods followed by pilot-scale testing using a fluidized bed desorber. As a result of the testing, Philip constructed a full-scale fluidized bed system which can recover mercury from contaminated soil and debris. The name of Philip`s technology is the Solvating Vapor Pressure Process (SVPP). The main purpose of this paper is to discuss the results of the SVPP pilot testing and describe the process.« less

  11. Photometric Studies of GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Cowardin, Heather M.; Barker, Edwin; Abercromby, Kira J.; Foreman, Gary; Horstman, Matt

    2009-01-01

    The photometric signature of a debris object can be useful in determining what the physical characteristics of a piece of debris are. We report on optical observations in multiple filters of debris at geosynchronous Earth orbit (GEO). Our sample is taken from GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the SMARTS (Small and Medium Aperture Research Telescope System) 0.9-m at CTIO for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R = 15 th magnitude that are discovered in the MODEST survey. At this magnitude the distribution of observed angular rates changes significantly from that of brighter objects. There are two objectives: 1. Estimate the orbital distribution of objects selected on the basis of two observational criteria: brightness (magnitude) and angular rates. 2. Obtain magnitudes and colors in standard astronomical filters (BVRI) for comparison with reflectance spectra of likely spacecraft materials. What is the faint debris likely to be? In this paper we report on the photometric results. For a sample of 50 objects, more than 90 calibrated sequences of R-B-V-I-R magnitudes have been obtained with the CTIO 0.9-m. For objects that do not show large brightness variations, the colors are largely redder than solar in both B-R and R-I. The width of the color distribution may be intrinsic to the nature of the surfaces, but also could be that we are seeing irregularly shaped objects and measuring the colors at different times with just one telescope. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO 0.9-m observes in B, and MODEST in R. The CCD cameras are electronically linked together so that the start time and duration of observations are the same to better than 50 milliseconds. Thus

  12. Conceptual design of an orbital debris collector

    NASA Technical Reports Server (NTRS)

    Odonoghue, Peter (Editor); Brenton, Brian; Chambers, Ernest; Schwind, Thomas; Swanhart, Christopher; Williams, Thomas

    1991-01-01

    The current Lower Earth Orbit (LEO) environment has become overly crowded with space debris. An evaluation of types of debris is presented in order to determine which debris poses the greatest threat to operation in space, and would therefore provide a feasible target for removal. A target meeting these functional requirements was found in the Cosmos C-1B Rocket Body. These launchers are spent space transporters which constitute a very grave risk of collision and fragmentation in LEO. The motion and physical characteristics of these rocket bodies have determined the most feasible method of removal. The proposed Orbital Debris Collector (ODC) device is designed to attach to the Orbital Maneuvering Vehicle (OMV), which provides all propulsion, tracking, and power systems. The OMV/ODC combination, the Rocket Body Retrieval Vehicle (RBRV), will match orbits with the rocket body, use a spin table to match the rotational motion of the debris, capture it, despin it, and remove it from orbit by allowing it to fall into the Earth's atmosphere. A disposal analysis is presented to show how the debris will be deorbited into the Earth's atmosphere. The conceptual means of operation of a sample mission is described.

  13. CDOT rapid debris removal research project.

    DOT National Transportation Integrated Search

    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...

  14. Wave Riemann description of friction terms in unsteady shallow flows: Application to water and mud/debris floods

    NASA Astrophysics Data System (ADS)

    Murillo, J.; García-Navarro, P.

    2012-02-01

    In this work, the source term discretization in hyperbolic conservation laws with source terms is considered using an approximate augmented Riemann solver. The technique is applied to the shallow water equations with bed slope and friction terms with the focus on the friction discretization. The augmented Roe approximate Riemann solver provides a family of weak solutions for the shallow water equations, that are the basis of the upwind treatment of the source term. This has proved successful to explain and to avoid the appearance of instabilities and negative values of the thickness of the water layer in cases of variable bottom topography. Here, this strategy is extended to capture the peculiarities that may arise when defining more ambitious scenarios, that may include relevant stresses in cases of mud/debris flow. The conclusions of this analysis lead to the definition of an accurate and robust first order finite volume scheme, able to handle correctly transient problems considering frictional stresses in both clean water and debris flow, including in this last case a correct modelling of stopping conditions.

  15. Space debris measurement program at Phillips Laboratory

    NASA Technical Reports Server (NTRS)

    Dao, Phan D.; Mcnutt, Ross T.

    1992-01-01

    Ground-based optical sensing was identified as a technique for measuring space debris complementary to radar in the critical debris size range of 1 to 10 cm. The Phillips Laboratory is building a staring optical sensor for space debris measurement and considering search and track optical measurement at additional sites. The staring sensor is implemented in collaboration with Wright Laboratory using the 2.5 m telescope at Wright Patterson AFB, Dayton, Ohio. The search and track sensor is designed to detect and track orbital debris in tasked orbits. A progress report and a discussion of sensor performance and search and track strategies will be given.

  16. Space debris, asteroids and satellite orbits; Proceedings of the Fourth and Thirteenth Workshops, Graz, Austria, June 25-July 7, 1984

    NASA Technical Reports Server (NTRS)

    Kessler, D. J.; Gruen, E.; Sehnal, L.

    1985-01-01

    The workshops covered a variety of topics relevant to the identification, characterization and monitoring of near-earth solar system debris. Attention was given to man-made and naturally occurring microparticles, their hazards to present and future spacecraft, and ground- and space-based techniques for tracking both large and small debris. The studies are extended to solid fuel particulates in circular space. Asteroid rendezvous missions are discussed, including propulsion and instrumentation options, the possibility of encountering asteroids during Hohman transfer flights to Venus and/or Mars, and the benefits of multiple encounters by one spacecraft. Finally, equipment and analytical models for generating precise satellite orbits are reviewed.

  17. Orbital Debris: the Growing Threat to Space Operations

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2010-01-01

    For nearly 50 years the amount of man-made debris in Earth orbit steadily grew, accounting for about 95% of all cataloged space objects over the past few decades. The Chinese anti-satellite test in January 2007 and the accidental collision of two spacecraft in February 2009 created more than 4000 new cataloged debris, representing an increase of 40% of the official U.S. Satellite Catalog. The frequency of collision avoidance maneuvers for both human space flight and robotic operations is increasing along with the orbital debris population. However, the principal threat to space operations is driven by the smaller and much more numerous uncataloged debris. Although the U.S. and the international aerospace communities have made significant progress in recognizing the hazards of orbital debris and in reducing or eliminating the potential for the creation of new debris, the future environment is expected to worsen without additional corrective measures.

  18. NOAA-USGS Debris-Flow Warning System - Final Report

    USGS Publications Warehouse

    ,

    2005-01-01

    Landslides and debris flows cause loss of life and millions of dollars in property damage annually in the United States (National Research Council, 2004). In an effort to reduce loss of life by debris flows, the National Oceanic and Atmospheric Administration's (NOAA) National Weather Service (NWS) and the U.S. Geological Survey (USGS) operated an experimental debris-flow prediction and warning system in the San Francisco Bay area from 1986 to 1995 that relied on forecasts and measurements of precipitation linked to empirical precipitation thresholds to predict the onset of rainfall-triggered debris flows. Since 1995, there have been substantial improvements in quantifying precipitation estimates and forecasts, development of better models for delineating landslide hazards, and advancements in geographic information technology that allow stronger spatial and temporal linkage between precipitation forecasts and hazard models. Unfortunately, there have also been several debris flows that have caused loss of life and property across the United States. Establishment of debris-flow warning systems in areas where linkages between rainfall amounts and debris-flow occurrence have been identified can help mitigate the hazards posed by these types of landslides. Development of a national warning system can help support the NOAA-USGS goal of issuing timely Warnings of potential debris flows to the affected populace and civil authorities on a broader scale. This document presents the findings and recommendations of a joint NOAA-USGS Task Force that assessed the current state-of-the-art in precipitation forecasting and debris-flow hazard-assessment techniques. This report includes an assessment of the science and resources needed to establish a demonstration debris-flow warning project in recently burned areas of southern California and the necessary scientific advancements and resources associated with expanding such a warning system to unburned areas and, possibly, to a

  19. Biological response to prosthetic debris

    PubMed Central

    Bitar, Diana; Parvizi, Javad

    2015-01-01

    Joint arthroplasty had revolutionized the outcome of orthopaedic surgery. Extensive and collaborative work of many innovator surgeons had led to the development of durable bearing surfaces, yet no single material is considered absolutely perfect. Generation of wear debris from any part of the prosthesis is unavoidable. Implant loosening secondary to osteolysis is the most common mode of failure of arthroplasty. Osteolysis is the resultant of complex contribution of the generated wear debris and the mechanical instability of the prosthetic components. Roughly speaking, all orthopedic biomaterials may induce a universal biologic host response to generated wear débris with little specific characteristics for each material; but some debris has been shown to be more cytotoxic than others. Prosthetic wear debris induces an extensive biological cascade of adverse cellular responses, where macrophages are the main cellular type involved in this hostile inflammatory process. Macrophages cause osteolysis indirectly by releasing numerous chemotactic inflammatory mediators, and directly by resorbing bone with their membrane microstructures. The bio-reactivity of wear particles depends on two major elements: particle characteristics (size, concentration and composition) and host characteristics. While any particle type may enhance hostile cellular reaction, cytological examination demonstrated that more than 70% of the debris burden is constituted of polyethylene particles. Comprehensive understanding of the intricate process of osteolysis is of utmost importance for future development of therapeutic modalities that may delay or prevent the disease progression. PMID:25793158

  20. Apparatus for controlling nuclear core debris

    DOEpatents

    Jones, Robert D.

    1978-01-01

    Nuclear reactor apparatus for containing, cooling, and dispersing reactor debris assumed to flow from the core area in the unlikely event of an accident causing core meltdown. The apparatus includes a plurality of horizontally disposed vertically spaced plates, having depressions to contain debris in controlled amounts, and a plurality of holes therein which provide natural circulation cooling and a path for debris to continue flowing downward to the plate beneath. The uppermost plates may also include generally vertical sections which form annular-like flow areas which assist the natural circulation cooling.

  1. Analysis of a space debris laser removal system

    NASA Astrophysics Data System (ADS)

    Gjesvold, Evan; Straub, Jeremy

    2017-05-01

    As long as man ventures into space, he will leave behind debris, and as long as he ventures into space, this debris will pose a threat to him and his projects. Space debris must be located and decommissioned. Lasers may prove to be the ideal method, as they can operate at a distance from the debris, have a theoretically infinite supply of energy from the sun, and are a seemingly readily available technology. This paper explores the requirements and reasoning for such a laser debris removal method. A case is made for the negligibility of eliminating rotational velocity from certain systems, while a design schematic is also presented for the implementation of a cube satellite proof of concept.

  2. The impact of debris on the Florida manatee

    USGS Publications Warehouse

    Beck, C.A.; Barros, N.B.

    1991-01-01

    The endangered Florida manatee ingests debris while feeding. From 1978 through 1986, 439 salvaged manatees were examined. Debris was in the gastrointestinal tract of 63 (14.4%) and four died as a direct result of debris ingestion. Monofilament fishing line was the most common debris found (N=49). Plastic bags, string, twine, rope, fish hooks, wire, paper, cellophane, synthetic sponges, rubber bands, and stockings also were recovered. Entanglement in lines and nets killed 11 manatees from 1974 through 1985. Numerous free-ranging manatees have missing or scarred flippers from entanglements, or debris still encircling one or both flippers. We recommend local cleanups, education of the public, and fishing restrictions in high use areas to significantly reduce harm to manatees.

  3. Modeling of circulating fluised beds for post-combustion carbon capture

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, A.; Shadle, L.; Miller, D.

    2011-01-01

    A compartment based model for a circulating fluidized bed reactor has been developed based on experimental observations of riser hydrodynamics. The model uses a cluster based approach to describe the two-phase behavior of circulating fluidized beds. Fundamental mass balance equations have been derived to describe the movement of both gas and solids though the system. Additional work is being performed to develop the correlations required to describe the hydrodynamics of the system. Initial testing of the model with experimental data shows promising results and highlights the importance of including end effects within the model.

  4. An Overview of NASA's Orbital Debris Engineering Model

    NASA Technical Reports Server (NTRS)

    Matney, Mark

    2010-01-01

    This slide presentation reviews the importance of Orbital debris engineering models. They are mathematical tools to assess orbital debris flux. It briefly reviews the history of the orbital debris engineering models, and reviews the new features in the current model (i.e., ORDEM2010).

  5. Linking effects of anthropogenic debris to ecological impacts.

    PubMed

    Browne, Mark Anthony; Underwood, A J; Chapman, M G; Williams, Rob; Thompson, Richard C; van Franeker, Jan A

    2015-05-22

    Accelerated contamination of habitats with debris has caused increased effort to determine ecological impacts. Strikingly, most work on organisms focuses on sublethal responses to plastic debris. This is controversial because (i) researchers have ignored medical insights about the mechanisms that link effects of debris across lower levels of biological organization to disease and mortality, and (ii) debris is considered non-hazardous by policy-makers, possibly because individuals can be injured or removed from populations and assemblages without ecological impacts. We reviewed the mechanisms that link effects of debris across lower levels of biological organization to assemblages and populations. Using plastic, we show microplastics reduce the 'health', feeding, growth and survival of ecosystem engineers. Larger debris alters assemblages because fishing-gear and tyres kill animals and damage habitat-forming plants, and because floating bottles facilitate recruitment and survival of novel taxa. Where ecological linkages are not known, we show how to establish hypothetical links by synthesizing studies to assess the likelihood of impacts. We also consider how population models examine ecological linkages and guide management of ecological impacts. We show that by focusing on linkages to ecological impacts rather than the presence of debris and its sublethal impacts, we could reduce threats posed by debris. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  6. Space Shuttle Systems Engineering Processes for Liftoff Debris Risk Mitigation

    NASA Technical Reports Server (NTRS)

    Mitchell, Michael; Riley, Christopher

    2011-01-01

    This slide presentation reviews the systems engineering process designed to reduce the risk from debris during Space Shuttle Launching. This process begins the day of launch from the tanking to the vehicle tower clearance. Other debris risks (i.e., Ascent, and micrometeoroid orbital debit) are mentioned) but are not the subject of this presentation. The Liftoff debris systems engineering process and an example of how it works are reviewed (i.e.,STS-119 revealed a bolt liberation trend on the Fixed Service Structure (FSS) 275 level elevator room). The process includes preparation of a Certification of Flight Readiness (CoFR) that includes (1) Lift-off debris from previous mission dispositioned, (2) Flight acceptance rationale has been provided for Lift-off debris sources/causes (3) Lift-off debris mission support documentation, processes and tools are in place for the up-coming mission. The process includes a liftoff debris data collection that occurs after each launch. This includes a post launch walkdown, that records each liftoff debris, and the entry of the debris into a database, it also includes a review of the imagery from the launch, and a review of the instrumentation data. There is also a review of the debris transport analysis process, that includes temporal and spatial framework and a computational fluid dynamics (CFD) analysis. which incorporates a debris transport analyses (DTA), debris materials and impact tests, and impact analyses.

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

    NASA Technical Reports Server (NTRS)

    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.

  8. Drone Use in Monioring Open Ocean Surface Debris, Including Paired Manta and Tucker Trawls for Relateing Sea State to Vertical Debris Distribution

    NASA Astrophysics Data System (ADS)

    Lattin, G.

    2016-02-01

    Monitoring debris at sea presents challenges not found in beach or riverine habitats, and is typically done with trawl nets of various apertures and mesh sizes, which limits the size of debris captured and the area surveyed. To partially overcome these limitations in monitoring floating debris, a Quadcopter drone with video transmitting and recording capabilities was deployed at the beginning and the end of manta trawl transects within the North Pacific Subtropical Gyre's eastern convergence zone. Subsurface tucker trawls at 10 meters were conducted at the same time as the manta trawls, in order to assess the effect of sea state on debris dispersal. Trawls were conducted on an 11 station grid used repeatedly since 1999. For drone observations, the operator and observer were stationed on the mother ship while two researchers collected observed debris using a rigid inflatable boat (RIB). The drone was flown to a distance of approximately 100 meters from the vessel in a zigzag or circular search pattern. Here we examine issues arising from drone deployment during the survey: 1) relation of area surveyed by drone to volume of water passing through trawl; 2) retrieval of drone-spotted and associated RIB spotted debris. 3) integrating post- flight image analysis into retrieved debris quantification; and 4) factors limiting drone effectiveness at sea. During the survey, debris too large for the manta trawl was spotted by the drone, and significant debris not observed using the drone was recovered by the RIB. The combination of drone sightings, RIB retrieval, and post flight image analysis leads to improved monitoring of debris at sea. We also examine the issue of the distribution of floating debris during sea states varying from 0-5 by comparing quantities from surface manta trawls to the tucker trawls at a nominal depth of 10 meters.

  9. Optimization of tannase production by Aspergillus niger in solid-state packed-bed bioreactor.

    PubMed

    Rodríguez-Durán, Luis V; Contreras-Esquivel, Juan C; Rodríguez, Raúl; Prado-Barragán, L Arely; Aguilar, Cristóbal N

    2011-09-01

    Tannin acyl hydrolase, also known as tannase, is an enzyme with important applications in the food, feed, pharmaceutical, and chemical industries. However, despite a growing interest in the catalytic properties of tannase, its practical use is very limited owing to high production costs. Several studies have already demonstrated the advantages of solid-state fermentation (SSF) for the production of fungal tannase, yet the optimal conditions for enzyme production strongly depend on the microbial strain utilized. Therefore, the aim of this study was to improve the tannase production by a locally isolated A. niger strain in an SSF system. The SSF was carried out in packed-bed bioreactors using polyurethane foam as an inert support impregnated with defined culture media. The process parameters influencing the enzyme production were identified using a Plackett–Burman design, where the substrate concentration, initial pH, and incubation temperature were determined as the most significant. These parameters were then further optimized using a Box-Behnken design. The maximum tannase production was obtained with a high tannic acid concentration (50 g/l), relatively low incubation temperature (30°C), and unique low initial pH (4.0). The statistical strategy aided in increasing the enzyme activity nearly 1.97-fold, from 4,030 to 7,955 U/l. Consequently, these findings can lead to the development of a fermentation system that is able to produce large amounts of tannase in economical, compact, and scalable reactors.

  10. Attrition of lime sorbents during fluidization in a circulating fluidized bed absorber

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, Sang Kwun; Keener, T.C.; Jiang, Xiaolin

    1993-11-01

    The experimental data of lime sorbent attrition obtained from mechanical and thermal attrition tests in a circulating fluidized bed absorber (CFBA) are represented. The results indicate that the predominant attrition mechanism during lime fluidization is surface abrasion due to collisions of the parent solids in a bed. Attrition of lime at higher temperatures decreased due to its hardened properties with rising temperature, while such solids as limestone become more attritable by the crepitation resulting from the increased internal pressure. With an introduction of the minimum weight of parent solids, the attrition rate of lime in a CFBA has a first-ordermore » dependency with respect to time. The attrition rate constant is expressed in an Arrhenius form, using the kinetic model which relates the attrition rate to the gas properties such as temperature and molecular weight and the geometry of the fluidized bed as well as the fluidization velocity. The experimental data obtained from these tests in a CFBA agree well with the attrition model, and the model indicates trends due to increased temperature considering thermal attrition. From the model the attrition activation energy, E[sub a] and k[sub o], can be obtained as E[sub a] = 3.383 [times] 10[sup [minus]3] kJ/kg and k[sub o] = 1.29 [times] 10[sup [minus]4]s[sup [minus]1], Comparisons of the mechanical and thermal attrition data obtained experimentally with the theoretical values computed with the attrition activation energy, E[sub a] and k[sub o], are in good agreement, and thus the results may be applicable to lime attrition in a fluidized bed.« less

  11. What's New for Laser Orbital Debris Removal

    NASA Astrophysics Data System (ADS)

    Phipps, Claude; Lander, Mike

    2011-11-01

    Orbital debris in low Earth orbit (LEO) are now sufficiently dense that the use of space is threatened by runaway collision cascading. A problem predicted more than thirty years ago, the threat from debris larger than about 1cm is now a reality that we ignore at our peril. The least costly, and most comprehensive, solution is Laser Orbital Debris Removal (LODR). In this approach, a high power pulsed laser on the Earth creates a laser-ablation jet on the debris object's surface which provides the small impulse required to cause it to re-enter and burn up in the atmosphere. The LODR system should be located near the Equator, and includes the laser, a large, agile mirror, and systems for active detection, tracking and atmospheric path correction. In this paper, we discuss advances that have occurred since LODR was first proposed, which make this solution to the debris problem look quite realistic.

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

    NASA Technical Reports Server (NTRS)

    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.

  13. Experimental modelling of flow - bed interactions in Jökulhlaups

    NASA Astrophysics Data System (ADS)

    Carrivick, J. L.; Xie, Z.; Sleigh, A.; Hubbard, M.

    2009-04-01

    Jökulhlaups (glacial outburst floods) are a sudden release and advancing wave of water and sediment from a glacier, with a peak discharge that is often several orders of magnitude greater than perennial flows. Jökulhlaup hazards are regularly incorporated into risk assessments for glaciated areas because the associated flood hazards are numerous. Jökulhlaup hazards are primarily due to direct impacts, caused by a frontal surge wave, from debris within a flow body, and from the mass and consistency of the flows. A number of secondary impacts also pose hazards, including widespread deposition of sediment and blocked tributary streams. It is rapid landscape change, which is achieved the mobilization and redistribution of sediment that causes one of the greatest hazards due to jökulhlaups. However, direct measurement of such phenomena is virtually impossible. The aim of this project is therefore to parameterise hydrodynamic - sedimentary interactions in experimental jökulhlaups. Specifically, this project applies laboratory flume modelling, which offers a hitherto untapped opportunity for examining complex interactions between water and sediment within outburst floods. The experimental set-up is of a tradition lock-gate design with a straight 4 m long tank. Hydraulics are scaled at 1:20 froude scale and the following controls on frontal wave flow-bed interactions and hence on rapid landscape change are being investigated: 1. Pre-existing mobile sediment effects, fixed bed roughness effects, sediment concentration effects, mobile bed effects. An emphasis is being maintained on examining the downstream temporal and spatial change in physical character of the water / sediment frontal wave. Facilities are state-of-the-art with a fully-automated laser bed-profiler to measure bed elevation after a run, Seatek arrays to measure transient flow depths, 0.5 Hz Ultrasonic Velocimeter Profiling to measure within-flow velocities, and Ultrasonic High-Concentration Meter (UHCM

  14. Using PVDF to locate the debris cloud impact position

    NASA Astrophysics Data System (ADS)

    Pang, Baojun; Liu, Zhidong

    2010-03-01

    With the increase of space activities, space debris environment has deteriorated. Space debris impact shields of spacecraft creates debris cloud, the debris cloud is a threat to module wall. In order to conduct an assessment of spacecraft module wall damage impacted by debris cloud, the damage position must be known. In order to design a light weight location system, polyvinylidene fluoride (PVDF) has been studied. Hyper-velocity impact experiments were conducted using two-stage light gas gun, the experimental results indicate that: the virtual wave front location method can be extended to debris cloud impact location, PVDF can be used to locate the damage position effectively, the signals gathered by PVDF from debris cloud impact contain more high frequency components than the signals created by single projectile impact event. The results provide a reference for the development of the sensor systems to detect impacts on spacecraft.

  15. Ability of bed bug-detecting canines to locate live bed bugs and viable bed bug eggs.

    PubMed

    Pfiester, Margie; Koehler, Philip G; Pereira, Roberto M

    2008-08-01

    The bed bug, Cimex lectularius L., like other bed bug species, is difficult to visually locate because it is cryptic. Detector dogs are useful for locating bed bugs because they use olfaction rather than vision. Dogs were trained to detect the bed bug (as few as one adult male or female) and viable bed bug eggs (five, collected 5-6 d after feeding) by using a modified food and verbal reward system. Their efficacy was tested with bed bugs and viable bed bug eggs placed in vented polyvinyl chloride containers. Dogs were able to discriminate bed bugs from Camponotus floridanus Buckley, Blattella germanica (L.), and Reticulitermes flavipes (Kollar), with a 97.5% positive indication rate (correct indication of bed bugs when present) and 0% false positives (incorrect indication of bed bugs when not present). Dogs also were able to discriminate live bed bugs and viable bed bug eggs from dead bed bugs, cast skins, and feces, with a 95% positive indication rate and a 3% false positive rate on bed bug feces. In a controlled experiment in hotel rooms, dogs were 98% accurate in locating live bed bugs. A pseudoscent prepared from pentane extraction of bed bugs was recognized by trained dogs as bed bug scent (100% indication). The pseudoscent could be used to facilitate detector dog training and quality assurance programs. If trained properly, dogs can be used effectively to locate live bed bugs and viable bed bug eggs.

  16. Analyzing costs of space debris mitigation methods

    NASA Astrophysics Data System (ADS)

    Wiedemann, C.; Krag, H.; Bendisch, J.; Sdunnus, H.

    The steadily increasing number of space objects poses a considerable hazard to all kinds of spacecraft. To reduce the risks to future space missions different debris mitigation measures and spacecraft protection techniques have been investigated during the last years. However, the economic efficiency has not been considered yet in this context. This economical background is not always clear to satellite operators and the space industry. Current studies have the objective to evaluate the mission costs due to space debris in a business as usual (no mitigation) scenario compared to the missions costs considering debris mitigation. The aim i an estimation of thes time until the investment in debris mitigation will lead to an effective reduction of mission costs. This paper presents the results of investigations on the key problems of cost estimation for spacecraft and the influence of debris mitigation and shielding on cost. The shielding of a satellite can be an effective method to protect the spacecraft against debris impact. Mitigation strategies like the reduction of orbital lifetime and de- or re-orbit of non-operational satellites are methods to control the space debris environment. These methods result in an increase of costs. In a first step the overall costs of different types of unmanned satellites are analyzed. The key problem is, that it is not possible to provide a simple cost model that can be applied to all types of satellites. Unmanned spacecraft differ very much in mission, complexity of design, payload and operational lifetime. It is important to classify relevant cost parameters and investigate their influence on the respective mission. The theory of empirical cost estimation and existing cost models are discussed. A selected cost model is simplified and generalized for an application on all operational satellites. In a next step the influence of space debris on cost is treated, if the implementation of mitigation strategies is considered.

  17. Debris mitigation methods for bridge piers.

    DOT National Transportation Integrated Search

    2012-06-01

    Debris accumulation on bridge piers is an on-going national problem that can obstruct the waterway openings at bridges and result in significant erosion of stream banks and scour at abutments and piers. In some cases, the accumulation of debris can a...

  18. The New NASA Orbital Debris Engineering Model ORDEM2000

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi; Matney, Mark J.; Anz-Meador, Phillip D.; Kessler, Donald; Jansen, Mark; Theall, Jeffery R.

    2002-01-01

    The NASA Orbital Debris Program Office at Johnson Space Center has developed a new computer-based orbital debris engineering model, ORDEM2000, which describes the orbital debris environment in the low Earth orbit region between 200 and 2000 km altitude. The model is appropriate for those engineering solutions requiring knowledge and estimates of the orbital debris environment (debris spatial density, flux, etc.). ORDEM2000 can also be used as a benchmark for ground-based debris measurements and observations. We incorporated a large set of observational data, covering the object size range from 10 mm to 10 m, into the ORDEM2000 debris database, utilizing a maximum likelihood estimator to convert observations into debris population probability distribution functions. These functions then form the basis of debris populations. We developed a finite element model to process the debris populations to form the debris environment. A more capable input and output structure and a user-friendly graphical user interface are also implemented in the model. ORDEM2000 has been subjected to a significant verification and validation effort. This document describes ORDEM2000, which supersedes the previous model, ORDEM96. The availability of new sensor and in situ data, as well as new analytical techniques, has enabled the construction of this new model. Section 1 describes the general requirements and scope of an engineering model. Data analyses and the theoretical formulation of the model are described in Sections 2 and 3. Section 4 describes the verification and validation effort and the sensitivity and uncertainty analyses. Finally, Section 5 describes the graphical user interface, software installation, and test cases for the user.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Orbital Debris Quarterly News. Volume 13; No. 1

    NASA Technical Reports Server (NTRS)

    Liou, J.-C. (Editor); Shoots, Debi (Editor)

    2009-01-01

    Topics discussed include: new debris from a decommissioned satellite with a nuclear power source; debris from the destruction of the Fengyun-1C meteorological satellite; quantitative analysis of the European Space Agency's Automated Transfer Vehicle 'Jules Verne' reentry event; microsatellite impact tests; solar cycle 24 predictions and other long-term projections and geosynchronus (GEO) environment for the Orbital Debris Engineering Model (ORDEM2008). Abstracts from the NASA Orbital Debris Program Office, examining satellite reentry risk assessments and statistical issues for uncontrolled reentry hazards, are also included.

  1. Experimental Study and Analytical Methods for Particle Bed Dryout With Heterogeneous Particles and Pressure Variation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Miettinen, Jaakko; Sairanen, Risto; Lindholm, Ilona

    2002-07-01

    The interest to study the dryout heat flux in particle beds is related to interest of quantify the debris coolability margins during a hypothetical severe reactor accident. When the molten core has relocated to the containment floor, one accident management concept is based on the cooling of the corium by the water injection on top. Earlier experimental and analytical work has concentrated on homogeneous particle beds at atmospheric pressures. For plant safety assessment in Finland, there is a need to consider heterogeneous particle mixtures, layered particle bed setups and varied pressures. A facility has been constructed at VTT to measuremore » dryout heat flux in a heterogeneous particle bed. The bed dimensions are 0.3 m in diameter and 0.6 m in height, with a mixture of 0.1 to 10 mm particles. The facility has a pressure range from atmospheric to 6 bar (overpressure). The bed is heated by spirals of a resistance band. The preliminary experiments have been carried out, but a more systematic set of data is expected to be available in the spring 2002. To support the experiments analytical models have been developed for qualification of the experimental results. The first comparison is done against various critical heat flux correlations developed in 1980's and 1990's for homogeneous bed conditions. The second comparison is done against 1-D and 0-D models developed by Lipinski. The most detailed analysis of the transient process conditions and dryout predictions are done by using the two-dimensional, drift-flux based thermohydraulic solution for the particle bed immersed into the water. The code is called PILEXP. Already the first validation results against the preliminary tests indicate that the transient process conditions and the mechanisms related to the dryout can be best explained and understood by using a multidimensional, transient code, where all details of the process control can be modeled as well. The heterogeneous bed and stratified bed can not be

  2. Analog and numerical experiments investigating force chain influences on bed conditions in granular flows

    NASA Astrophysics Data System (ADS)

    Estep, J.; Dufek, J.

    2013-12-01

    Granular flows are fundamental processes in several terrestrial and planetary natural events; including surficial flows on volcanic edifices, debris flows, landslides, dune formation, rock falls, sector collapses, and avalanches. Often granular flows can be two-phase, whereby interstitial fluids occupy void space within the particulates. The mobility of granular flows has received significant attention, however the physics that govern their internal behavior remain poorly understood. Here we extend upon previous research showing that force chains can transmit extreme localized forces to the substrates of free surface granular flows, and we combine experimental and computational approaches to further investigate the forces at the bed of simplified granular flows. Analog experiments resolve discrete bed forces via a photoelastic technique, while numerical experiments validate laboratory tests using discrete element model (DEM) simulations. The current work investigates (1) the role of distributed grain sizes on force transmission via force chains, and (2) how the inclusion of interstitial fluids effects force chain development. We also include 3D numerical simulations to apply observed 2D characteristics into real world perspective, and ascertain if the added dimension alters force chain behavior. Previous research showed that bed forces generated by force chain structures can transiently greatly exceed (by several 100%) the bed forces predicted from continuum approaches, and that natural materials are more prone to excessive bed forces than photoelastic materials due to their larger contact stiffnesses. This work suggests that force chain activity may play an important role in the bed physics of dense granular flows by influencing substrate entrainment. Photoelastic experiment image showing force chains in gravity driven granular flow.

  3. Particle size variations between bed load and bed material in natural gravel bed channels

    Treesearch

    Thomas E. Lisle

    1995-01-01

    Abstract - Particle sizes of bed load and bed material that represent materials transported and stored over a period of years are used to investigate selective transport in 13 previously sampled, natural gravel bed channels. The ratio (D*) of median particle size of bed material to the transport- and frequency-weighted mean of median bed load size decreases to unity...

  4. Effects of 1997 debris floods in two Klamath Mountain streams: A large woody debris mass-balance approach

    Treesearch

    Zackary J. Mondry; Susan J. Hilton

    2000-01-01

    Large landslides and debris flows in January 1997 produced contrasting downstream debris flood effects in two adjacent Northern California Klamath Mountain streams. Valley morphology and riparian forests were examined on post-flood 1:3000 air photos along two approximately 8 km survey reaches.

  5. Space Shuttle crew compartment debris-contamination

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Villarreal, Leopoldo J.

    1992-01-01

    Remedial actions undertaken to reduce debris during manned flights and ground turnaround operations at Kennedy Space Center and Palmdale are addressed. They include redesign of selected ground support equipment and Orbiter hardware to reduce particularization/debris generation; development of new detachable filters for air-cooled avionics boxes; application of tape-on screens to filter debris; and implementation of new Orbiter maintenance and turnaround procedures to clean filters and the crew compartment. Most of these steps were implemented before the return-to-flight of STS-26 in September 1988 which resulted in improved crew compartment habitability and less potential for equipment malfunction.

  6. Collector/Compactor for Waste or Debris

    NASA Technical Reports Server (NTRS)

    Mangialiardi, John K.

    1987-01-01

    Device collects and compacts debris by sweeping through volume with net. Consists of movable vane, fixed vane, and elastic net connected to both vanes. Movable vane is metal strip curved to follow general contour of container with clearance to prevent interference with other parts on inside wall of container. One end of movable vane mounted in bearing and other end connected to driveshaft equipped with handle. User rotates movable vane, net stretched and swept through container. Captures most of debris coarser than mesh as it moves, compressing debris as it arrives at fixed vane. Applications include cleaning swimming pools and tanks.

  7. Assessing marine debris in deep seafloor habitats off California.

    PubMed

    Watters, Diana L; Yoklavich, Mary M; Love, Milton S; Schroeder, Donna M

    2010-01-01

    Marine debris is a global concern that pollutes the world's oceans, including deep benthic habitats where little is known about the extent of the problem. We provide the first quantitative assessment of debris on the seafloor (20-365 m depth) in submarine canyons and the continental shelf off California, using the Delta submersible. Fishing activities were the most common contributors of debris. Highest densities occurred close to ports off central California and increased significantly over the 15-year study period. Recreational monofilament fishing line dominated this debris. Debris was less dense and more diverse off southern than central California. Plastic was the most abundant material and will likely persist for centuries. Disturbance to habitat and organisms was low, and debris was used as habitat by some fishes and macroinvertebrates. Future trends in human activities on land and at sea will determine the type and magnitude of debris that accumulates in deep water. Published by Elsevier Ltd.

  8. The innovative moving bed biofilm reactor/solids contact reaeration process for secondary treatment of municipal wastewater

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rusten, B.; McCoy, M.; Proctor, R.

    1998-07-01

    The innovative moving bed biofilm reactor/solids contact reaeration (MBBR/SCR) process has been chosen for a new wastewater treatment plant serving a population of 200,000 at Moa Point, Wellington, New Zealand. Because the MBBR/SCR combination was new, a pilot-scale demonstration project was made part of the contract. Thorough pilot tests using a wide range of organic loads under both steady and transient-flow conditions demonstrated that the MBBR/SCR process produced the required effluent quality at loads higher than used in the original design. At 3 days mean cell residence time (MCRT) in the SCR stage, a final effluent with a 5-day biochemicalmore » oxygen demand (BOD{sub 5}) of less than 10 mg/L was achieved at an organic load on the MBBR of 15 g BOD{sub 5}/m{sup 2}{center_dot}d (5.0 kg BOD{sub 5}/m{sup 3}{center_dot}d). With the same MCRT, a final effluent of less than 15 mg BOD{sub 5}/L was achieved at an organic load on the MBBR of 20 g BOD{sub 5}/m{sup 2}{center_dot}d (6.7 kg BOD{sub 5}/m{sup 3}{center_dot}d). Dynamic loading tests demonstrated that a good-quality effluent was produced with a diurnal peak-hour load on the MBBR of more than 40 g BOD{sub 5}/m{sup 2}{center_dot}d (13.3 kg BOD{sub 5}/m{sup 3}{center_dot}d). The MBBR/SCR process was more compact and significantly cheaper than a conventional trickling filter/solids contact or activated-sludge process at the Moa Point site.« less

  9. Rheological characteristics of waste rock materials in abandoned mine deposit and debris flow hazards

    NASA Astrophysics Data System (ADS)

    Jeong, Sueng-Won; Lee, Choonoh; Cho, Yong-Chan; Wu, Ying-Hsin

    2015-04-01

    In Korea, approximately 5,000 metal mines are spread, but 50% of them are still abandoned without any proper remediation and cleanup. Summer heavy rainfall can result in the physicochemical modification of waste rock materials in the mountainous. From the geotechnical monitoring and field investigation, there are visible traces of mass movements every year. Soil erosion is one of severe phenomena in the study area. In particular, study area is located in the upper part of the Busan Metropolitan City and near the city's water supply. With respect to the supply of drinking water and maintenance of ecological balance, proper disposal of waste rock materials is required. For this reason, we examine the rheological properties of waste rock materials as a function of solid content using a ball- and vane-penetrated rheometer. In the flow curves, which are the relationship between the shear stress and shear rate of waste rock materials, we found that the soil samples exhibited a shear thinning beahivor regardless of solid content. The Bingham, Herschel-Bulkley, Power-law, and Papanastasiou models are used to determine the rheological properties. Assuming that the soil samples behaved as the viscoplastic behavior, the yield stress and viscosity are determined for different water contents. As a result, there are clear relationships between the solid content and rheological values (i.e., Bingham yield stress and plastic viscosity). From these relationships, the maximum and minimum of Bingham yield stresses are ranged from 100 to 2000 Pa. The debris flow mobilization is analysed using a 1D BING and 2D Debris flow models. In addition, the effect of wall slip and test apparatus are discussed.

  10. Modernization of Deployable Airfield Debris Removal Equipment

    DTIC Science & Technology

    2017-04-01

    cleared the debris away from the crater by lowering the front bucket and setting the bottom blade at a 45-deg angle. The debris was pushed...the Komatsu WA 150 baseline loader. The crater clearing process involved the loader orienting the bucket blade at approximately 45 deg to the...wider than the track’s width (Figure 30). This caused debris to run under the track and lift the equipment, potentially throwing the operator. The final

  11. Predicting sediment delivery from debris flows after wildfire

    NASA Astrophysics Data System (ADS)

    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

  12. The origins of Late Quaternary debris avalanche and debris flow deposits from Cofre de Perote volcano, México

    USGS Publications Warehouse

    Diaz-Castellon, Rodolfo; Hubbard, Bernard E.; Carrasco-Nunez, Gerardo; Rodríguez-Vargas, José Luis

    2012-01-01

    Cofre de Perote volcano is a compound, shield-like volcano located in the northeastern Trans-Mexican volcanic belt. Large debris avalanche and lahar deposits are associated with the evolution of Cofre. The two best preserved of these debris-avalanche and debris-flow deposits are the ∼42 ka “Los Pescados debris flow” deposit and the ∼11–13 ka “Xico avalanche” deposit, both of which display contrasting morphological and textural characteristics, source materials, origins and emplacement environments. Laboratory X-ray diffraction and visible-infrared reflectance spectroscopy were used to identify the most abundant clay, sulfate, ferric-iron, and silica minerals in the deposits, which were either related to hydrothermal alteration or chemical weathering processes. Cloud-free Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) remote sensing imagery, supporting EO-1 Hyperion image spectra, and field ground truth samples were used to map the mineralogy and distribution of hydrothermally altered rocks on the modern summit of Cofre de Perote. The results were then compared to minerals identified in the two debris-avalanche and debris-flow deposits in order to assess possible source materials and origins for the two deposits.The older Los Pescados debris-flow deposit contains mostly halloysite and hydrous silica minerals, which match the dominant mineralogy of soils and weathered volcanic deposit in the surrounding flanks of Cofre de Perote. Its source materials were most likely derived from initially noncohesive or clay-poor flows, which subsequently bulked with clay-rich valley soils and alluvium in a manner similar to lahars from Nevado del Ruiz in 1985, but on a larger scale. The younger Xico avalanche deposit contains abundant smectite, jarosite, kaolinite, gypsum, and mixed-layered illite/smectite, which are either definitely or most likely of hydrothermal alteration origin. Smectite in particular appears to be the most abundant and

  13. Tracking Debris Shed by a Space-Shuttle Launch Vehicle

    NASA Technical Reports Server (NTRS)

    Stuart, Phillip C.; Rogers, Stuart E.

    2009-01-01

    The DEBRIS software predicts the trajectories of debris particles shed by a space-shuttle launch vehicle during ascent, to aid in assessing potential harm to the space-shuttle orbiter and crew. The user specifies the location of release and other initial conditions for a debris particle. DEBRIS tracks the particle within an overset grid system by means of a computational fluid dynamics (CFD) simulation of the local flow field and a ballistic simulation that takes account of the mass of the particle and its aerodynamic properties in the flow field. The computed particle trajectory is stored in a file to be post-processed by other software for viewing and analyzing the trajectory. DEBRIS supplants a prior debris tracking code that took .15 minutes to calculate a single particle trajectory: DEBRIS can calculate 1,000 trajectories in .20 seconds on a desktop computer. Other improvements over the prior code include adaptive time-stepping to ensure accuracy, forcing at least one step per grid cell to ensure resolution of all CFD-resolved flow features, ability to simulate rebound of debris from surfaces, extensive error checking, a builtin suite of test cases, and dynamic allocation of memory.

  14. Active Debris Removal and the Challenges for Environment Remediation

    NASA Technical Reports Server (NTRS)

    Liou, J. C.

    2012-01-01

    Recent modeling studies on the instability of the debris population in the low Earth orbit (LEO) region and the collision between Iridium 33 and Cosmos 2251 have underlined the need for active debris removal. A 2009 analysis by the NASA Orbital Debris Program Office shows that, in order to maintain the LEO debris population at a constant level for the next 200 years, an active debris removal of about five objects per year is needed. The targets identified for removal are those with the highest mass and collision probability products in the environment. Many of these objects are spent upper stages with masses ranging from 1 to more than 8 metric tons, residing in several altitude regions and concentrated in about 7 inclination bands. To remove five of those objects on a yearly basis, in a cost-effective manner, represents many challenges in technology development, engineering, and operations. This paper outlines the fundamental rationale for considering active debris removal and addresses the two possible objectives of the operations -- removing large debris to stabilize the environment and removing small debris to reduce the threat to operational spacecraft. Technological and engineering challenges associated with the two different objectives are also discussed.

  15. Thin layer drying of cassava starch using continuous vibrated fluidized bed dryer

    NASA Astrophysics Data System (ADS)

    Suherman, Trisnaningtyas, Rona

    2015-12-01

    This paper present the experimental work and thin layer modelling of cassava starch drying in continuous vibrated fluidized bed dryer. The experimental data was used to validate nine thin layer models of drying curve. Cassava starch with 0.21 initial moisture content was dried in different air drying temperature (50°C, 55°C, 60°C, 65°C, 70°C), different weir height in bed (0 and 1 cm), and different solid feed flow (10 and 30 gr.minute-1). The result showed air dryer temperature has a significant effect on drying curve, while the weir height and solid flow rate are slightly. Based on value of R2, χ2, and RMSE, Page Model is the most accurate simulation for thin layer drying model of cassava starch.

  16. Comparison of the meteorology and surface energy fluxes of debris-free and debris-covered glaciers in the southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yang, W.

    2017-12-01

    Knowledge of the meteorology and energy fluxes of debris-free and debris-covered glaciers is important for understanding the varying response of glaciers to climate change. Field measurements at the debris-free Parlung No. 4 Glacier and the debris-covered 24K Glacier in the southeastern Tibetan Plateau were carried out to compare the meteorology and surface energy fluxes and to understand the factors controlling the melting process. The meteorological comparisons displayed temporally synchronous fluctuations in air temperature, relative humidity, incoming longwave radiation (Lin), but notable differences in precipitation, incoming shortwave radiation (Sin) and wind speed. Under the prevailing regional precipitation and debris conditions, more Lin (42 W/m2) was supplied from warmer and more humid air and more Sin (58 W/m2) was absorbed at the 24K Glacier. The relatively high energy supply led mainly to an increased energy output via turbulent heat fluxes and outgoing longwave radiation, rather than glacier melting beneath the thick debris. The sensitivity experiment showed that melting rates were sensitive to variations in energy supply with debris thicknesses of less than 10 cm. In contrast, energy supply to the ablation zone of the Parlung No. 4 Glacier mainly resulted in snow/ice melting, the magnitude of which was significantly influenced by the energy supplied by Sin and the sensible heat flux.

  17. Risk assessment of debris flow hazards in natural slope

    NASA Astrophysics Data System (ADS)

    Choi, Junghae; Chae, Byung-gon; Liu, Kofei; Wu, Yinghsin

    2016-04-01

    The study area is located at north-east part of South Korea. Referring to the map of landslide sus-ceptibility (KIGAM, 2009) from Korea Institute of Geoscience and Mineral Resources (KIGAM for short), there are large areas of potential landslide in high probability on slope land of mountain near the study area. Besides, recently some severe landslide-induced debris flow hazards occurred in this area. So this site is convinced to be prone to debris flow haz-ards. In order to mitigate the influence of hazards, the assessment of potential debris flow hazards is very important and essential. In this assessment, we use Debris-2D, debris flow numerical program, to assess the potential debris flow hazards. The worst scenario is considered for simulation. The input mass sources are determined using landslide susceptibility map. The water input is referred to the daily accumulative rainfall in the past debris flow event in study area. The only one input material property, i.e. yield stress, is obtained using calibration test. The simulation results show that the study area has po-tential to be impacted by debris flow. Therefore, based on simulation results, to mitigate debris flow hazards, we can propose countermeasures, including building check dams, constructing a protection wall in study area, and installing instruments for active monitoring of debris flow hazards. Acknowledgements:This research was supported by the Public Welfare & Safety Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2012M3A2A1050983)

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

    PubMed

    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.

  19. On the debris-level origins of adhesive wear

    NASA Astrophysics Data System (ADS)

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

    2017-07-01

    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.

  20. Orbital Debris Environment Assessment and Mitigation for Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2007-01-01

    This viewgraph presentation reviews the debris that is in orbit, and reduction of the orbital debris. Specifically, attention is paid to the reduction of orbital debris from launch vehicle stages after the launch.

  1. Using multiple bed load measurements: Toward the identification of bed dilation and contraction in gravel-bed rivers

    NASA Astrophysics Data System (ADS)

    Marquis, G. A.; Roy, A. G.

    2012-02-01

    This study examines bed load transport processes in a small gravel-bed river (Béard Creek, Québec) using three complementary methods: bed elevation changes between successive floods, bed activity surveys using tags inserted into the bed, and bed load transport rates from bed load traps. The analysis of 20 flood events capable of mobilizing bed material led to the identification of divergent results among the methods. In particular, bed elevation changes were not consistent with the bed activity surveys. In many cases, bed elevation changes were significant (1 to 2 times the D50) even if the bed surface had not been activated during the flood, leading to the identification of processes of bed dilation and contraction that occurred over 10% to 40% of the bed surface. These dynamics of the river bed prevent accurate derivation of bed load transport rates from topographic changes, especially for low magnitude floods. This paper discusses the mechanisms that could explain the dilation and contraction of particles within the bed and their implications in fluvial dynamics. Bed contraction seems to be the result of the winnowing of the fine sediments under very low gravel transport. Bed dilation seems to occur on patches of the bed at the threshold of motion where various processes such as fine sediment infiltration lead to the maintenance of a larger sediment framework volume. Both processes are also influenced by flood history and the initial local bed state and in turn may have a significant impact on sediment transport and morphological changes in gravel-bed rivers.

  2. 14 CFR 417.211 - Debris analysis.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Debris analysis. 417.211 Section 417.211 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.211 Debris analysis. (a) General. A flight...

  3. 14 CFR 417.211 - Debris analysis.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Debris analysis. 417.211 Section 417.211 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.211 Debris analysis. (a) General. A flight...

  4. 14 CFR 417.211 - Debris analysis.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Debris analysis. 417.211 Section 417.211 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.211 Debris analysis. (a) General. A flight...

  5. 14 CFR 417.211 - Debris analysis.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Debris analysis. 417.211 Section 417.211 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.211 Debris analysis. (a) General. A flight...

  6. 14 CFR 417.211 - Debris analysis.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Debris analysis. 417.211 Section 417.211 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.211 Debris analysis. (a) General. A flight...

  7. Effect of filter media thickness on the performance of sand drying beds used for faecal sludge management.

    PubMed

    Manga, M; Evans, B E; Camargo-Valero, M A; Horan, N J

    2016-12-01

    The effect of sand filter media thickness on the performance of faecal sludge (FS) drying beds was determined in terms of: dewatering time, contaminant load removal efficiency, solids generation rate, nutrient content and helminth eggs viability in the dried sludge. A mixture of ventilated improved pit latrine sludge and septage in the ratio 1:2 was dewatered using three pilot-scale sludge drying beds with sand media thicknesses of 150, 250 and 350 mm. Five dewatering cycles were conducted and monitored for each drying bed. Although the 150 mm filter had the shortest average dewatering time of 3.65 days followed by 250 mm and 350 mm filters with 3.83 and 4.02 days, respectively, there was no significant difference (p > 0.05) attributable to filter media thickness configurations. However, there was a significant difference for the percolate contaminant loads in the removal and recovery efficiency of suspended solids, total solids, total volatile solids, nitrogen species, total phosphorus, chemical oxygen demand, dissolved chemical oxygen demand and biochemical oxygen demand, with the highest removal efficiency for each parameter achieved by the 350 mm filter. There were also significant differences in the nutrient content (NPK) and helminth eggs viability of the solids generated by the tested filters. Filtering media configurations similar to 350 mm have the greatest potential for optimising nutrient recovery from FS.

  8. Reading the Signatures of Extrasolar Planets in Debris Disks

    NASA Technical Reports Server (NTRS)

    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.

  9. ICE AND DEBRIS IN THE FRETTED TERRAIN, MARS.

    USGS Publications Warehouse

    Lucchitta, Baerbel K.

    1984-01-01

    Viking moderate- and high-resolution images along the northern highland margin were studied monoscopically and stereoscopically to contribute to an understanding of the development of fretted terrain. Results support the hypothesis that the fretting process involved flow facilitated by interstitial ice. The process apparently continued for a long period of time, and debris-apron formation shaped the fretted terrain in the past as well as the present. Interstitial ice in debris aprons is most likely derived from ground ice obtained by sapping or scarp collapse. Debris aprons could have been removed by sublimation if they consisted mostly of ice, or by deflation if they consisted mostly of debris. To remove the debris, wind erosion was either very intense early in martian history, or was intermittent, perhaps owing to climatic cycles.

  10. Biobjective planning of an active debris removal mission

    NASA Astrophysics Data System (ADS)

    Madakat, Dalal; Morio, Jérôme; Vanderpooten, Daniel

    2013-03-01

    The growth of the orbital debris population has been a concern to the international space community for several years. Recent studies have shown that the debris environment in Low Earth Orbit (LEO, defined as the region up to 2000 km altitude) has reached a point where the debris population will continue to increase even if all future launches are suspended. As the orbits of these objects often overlap the trajectories of satellites, debris create a potential collision risk. However, several studies show that about 5 objects per year should be removed in order to keep the future LEO environment stable. In this article, we propose a biobjective time dependent traveling salesman problem (BiTDTSP) model for the problem of optimally removing debris and use a branch and bound approach to deal with it.

  11. Disaster Debris Recovery Database - Recovery

    EPA Pesticide Factsheets

    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.

  12. Disaster Debris Recovery Database - Landfills

    EPA Pesticide Factsheets

    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.

  13. A Comparison of the SOCIT and DebriSat Experiments

    NASA Technical Reports Server (NTRS)

    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

  14. A Search for Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Lederer, Susan M.; Barker, Edwin S.; Cowardin, Heather; Abercromby, Kira J.; ilha, Jiri

    2011-01-01

    Existing optical surveys for debris at geosynchronous orbit (GEO) have been conducted with meter class telescopes, which have detection limits in the range of 18th-19th magnitude. We report on a new search for optically faint debris at GEO using the 6.5-m Magellan 1 telescope Walter Baade at Las Campanas Observatory in Chile. Our goal is to go as faint as possible and characterize the brightness distribution of debris fainter than R = 20th magnitude, corresponding to a size smaller than 10 cm assuming an albedo of 0.175. We wish to compare the inferred size distribution for GEO debris with that for LEO debris. We describe results obtained during 9.4 hours of observing time during 25-27 March 2011. We used the IMACS f/2 instrument, which has a mosaic of 8 CCDs, and a field of view of 30 arc-minutes in diameter. This is the widest field of view of any instrument on either Magellan telescope. All observations were obtained through a Sloan r filter. The limiting magnitude for 5 second exposures is estimated to be fainter than 22. With this small field of view and the limited observing time, our objective was to search for optically faint objects from the Titan 3C Transtage (1968-081) fragmentation in 1992. Eight debris pieces and the parent rocket body are in the Space Surveillance Network public catalog. We successfully tracked two cataloged pieces of Titan debris (SSN # 25001 and 33519) with the 6.5-m telescope, followed by a survey for objects on similar orbits but with a spread in mean anomaly. To detect bright objects over a wider field of view (1.6x1.6 degrees), we observed the same field centers at the same time through a similar filter with the 0.6-m MODEST (Michigan Orbital DEbris Survey Telescope), located 100 km to the south of Magellan at Cerro Tololo Inter-American Observatory, Chile. We will describe our experiences using Magellan, a telescope never used previously for orbital debris research, and our initial results.

  15. Three-dimensional flow structure and patterns of bed shear stress in an evolving compound meander bend

    USGS Publications Warehouse

    Engel, Frank; Rhoads, Bruce L.

    2016-01-01

    Compound meander bends with multiple lobes of maximum curvature are common in actively evolving lowland rivers. Interaction among spatial patterns of mean flow, turbulence, bed morphology, bank failures and channel migration in compound bends is poorly understood. In this paper, acoustic Doppler current profiler (ADCP) measurements of the three-dimensional (3D) flow velocities in a compound bend are examined to evaluate the influence of channel curvature and hydrologic variability on the structure of flow within the bend. Flow structure at various flow stages is related to changes in bed morphology over the study timeframe. Increases in local curvature within the upstream lobe of the bend reduce outer bank velocities at morphologically significant flows, creating a region that protects the bank from high momentum flow and high bed shear stresses. The dimensionless radius of curvature in the upstream lobe is one-third less than that of the downstream lobe, with average bank erosion rates less than half of the erosion rates for the downstream lobe. Higher bank erosion rates within the downstream lobe correspond to the shift in a core of high velocity and bed shear stresses toward the outer bank as flow moves through the two lobes. These erosion patterns provide a mechanism for continued migration of the downstream lobe in the near future. Bed material size distributions within the bend correspond to spatial patterns of bed shear stress magnitudes, indicating that bed material sorting within the bend is governed by bed shear stress. Results suggest that patterns of flow, sediment entrainment, and planform evolution in compound meander bends are more complex than in simple meander bends. Moreover, interactions among local influences on the flow, such as woody debris, local topographic steering, and locally high curvature, tend to cause compound bends to evolve toward increasing planform complexity over time rather than stable configurations.

  16. A Laser Optical System to Remove Low Earth Orbit Space Debris

    NASA Astrophysics Data System (ADS)

    Phipps, Claude R.; Baker, Kevin L.; Libby, Stephen B.; Liedahl, Duane A.; Olivier, Scot S.; Pleasance, Lyn D.; Rubenchik, Alexander; Nikolaev, Sergey; Trebes, James E.; George, Victor E.; Marrcovici, Bogdan; Valley, Michael T.

    2013-08-01

    Collisions between existing Low Earth Orbit (LEO) debris are now a main source of new debris, threatening future use of LEO space. As solutions, flying up and interacting with each object is inefficient due to the energy cost of orbit plane changes, while debris removal systems using blocks of aerogel or gas-filled balloons are prohibitively expensive. Furthermore, these solutions to the debris problem address only large debris, but it is also imperative to remove 10-cm-class debris. In Laser-Orbital-Debris-Removal (LODR), a ground-based pulsed laser makes plasma jets on LEO debris objects, slowing them slightly, and causing them to re-enter the atmosphere and burn up. LODR takes advantage of recent advances in pulsed lasers, large mirrors, nonlinear optics and acquisition systems. LODR is the only solution that can address both large and small debris. International cooperation is essential for building and operating such a system. We also briefly discuss the orbiting laser debris removal alternative.

  17. Comparison of national space debris mitigation standards

    NASA Astrophysics Data System (ADS)

    Kato, A.

    2001-01-01

    Several national organizations of the space faring nations have established Space Debris Mitigation Standards or Handbooks to promote efforts to deal with the space debris issue. This paper introduces the characteristics of each document and compares the structure, items and level of requirements. The contents of these standards may be slightly different from each other but the fundamental principles are almost the same; they are (1) prevention of on-orbit breakups, (2) removal of mission terminated spacecraft from the useful orbit regions, and (3) limiting the objects released during normal operations. The Inter-Agency Space Debris Coordination Committee has contributed considerably to this trend. The Committee also found out by its recent survey that some commercial companies have begun to adopt the debris mitigation measures for their projects. However, the number of organizations that have initiated this kind of self-control is still limited, so the next challenge of the Committee is to promote the Space Debris Mitigation Guidelines world-wide. IADC initiated this project in October 1999 and a draft is being circulated among the member agencies.

  18. Final design of a space debris removal system

    NASA Astrophysics Data System (ADS)

    Carlson, Erika; Casali, Steve; Chambers, Don; Geissler, Garner; Lalich, Andrew; Leipold, Manfred; Mach, Richard; Parry, John; Weems, Foley

    1990-12-01

    The objective is the removal of medium sized orbital debris in low Earth orbits. The design incorporates a transfer vehicle and a netting vehicle to capture the medium size debris. The system is based near an operational space station located at 28.5 degrees inclination and 400 km altitude. The system uses ground based tracking to determine the location of a satellite breakup or debris cloud. This data is unloaded to the transfer vehicle, and the transfer vehicle proceeds to rendezvous with the debris at a lower altitude parking orbit. Next, the netting vehicle is deployed, tracks the targeted debris, and captures it. After expending the available nets, the netting vehicle returns to the transfer vehicle for a new netting module and continues to capture more debris in the target area. Once all the netting modules are expended, the transfer vehicle returns to the space station's orbit, where it is resupplied with new netting modules from a space shuttle load. The new modules are launched by the shuttle from the ground, and the expended modules are taken back to Earth for removal of the captured debris, refueling, and repacking of the nets. Once the netting modules are refurbished, they are taken back into orbit for reuse. In a typical mission, the system has the ability to capture 50 pieces of orbital debris. One mission will take about six months. The system is designed to allow for a 30 degree inclination change on the outgoing and incoming trips of the transfer vehicle.

  19. Final design of a space debris removal system

    NASA Technical Reports Server (NTRS)

    Carlson, Erika; Casali, Steve; Chambers, Don; Geissler, Garner; Lalich, Andrew; Leipold, Manfred; Mach, Richard; Parry, John; Weems, Foley

    1990-01-01

    The objective is the removal of medium sized orbital debris in low Earth orbits. The design incorporates a transfer vehicle and a netting vehicle to capture the medium size debris. The system is based near an operational space station located at 28.5 degrees inclination and 400 km altitude. The system uses ground based tracking to determine the location of a satellite breakup or debris cloud. This data is unloaded to the transfer vehicle, and the transfer vehicle proceeds to rendezvous with the debris at a lower altitude parking orbit. Next, the netting vehicle is deployed, tracks the targeted debris, and captures it. After expending the available nets, the netting vehicle returns to the transfer vehicle for a new netting module and continues to capture more debris in the target area. Once all the netting modules are expended, the transfer vehicle returns to the space station's orbit, where it is resupplied with new netting modules from a space shuttle load. The new modules are launched by the shuttle from the ground, and the expended modules are taken back to Earth for removal of the captured debris, refueling, and repacking of the nets. Once the netting modules are refurbished, they are taken back into orbit for reuse. In a typical mission, the system has the ability to capture 50 pieces of orbital debris. One mission will take about six months. The system is designed to allow for a 30 degree inclination change on the outgoing and incoming trips of the transfer vehicle.

  20. Launch Vehicle Debris Models and Crew Vehicle Ascent Abort Risk

    NASA Technical Reports Server (NTRS)

    Gee, Ken; Lawrence, Scott

    2013-01-01

    For manned space launch systems, a reliable abort system is required to reduce the risks associated with a launch vehicle failure during ascent. Understanding the risks associated with failure environments can be achieved through the use of physics-based models of these environments. Debris fields due to destruction of the launch vehicle is one such environment. To better analyze the risk posed by debris, a physics-based model for generating launch vehicle debris catalogs has been developed. The model predicts the mass distribution of the debris field based on formulae developed from analysis of explosions. Imparted velocity distributions are computed using a shock-physics code to model the explosions within the launch vehicle. A comparison of the debris catalog with an existing catalog for the Shuttle external tank show good comparison in the debris characteristics and the predicted debris strike probability. The model is used to analyze the effects of number of debris pieces and velocity distributions on the strike probability and risk.